Emeritus Faculty - University Medical Line, Pediatrics - Gastroenterology
ATTENDING PHYSICIAN, LIVER TRANSPLANTATION, PACKARD CHILDREN'S HOSPITAL, STANFORD UNIVERSITY (1985 - Present)
MEDICAL DIRECTOR, INTESTINAL TRANSPLANTATION, PACKARD CHILDREN'S HOSPITAL, STANFORD UNIVERSITY (1999 - Present)
DIRECTOR, PROGRAM IN INTESTINAL REHABILITATION, PACKARD CHILDREN'S HOSPITAL, STANFORD UNIVERSITY (2005 - Present)
Honors & Awards
WILLIAM M. HUME FACULTY SCHOLAR, STANFORD UNIVERSITY (1987)
FELLOWSHIP, U.C. SAN FRANCISCO, GASTROENTEROLOGY (1982)
RESIDENCY, STANFORD UNIVERSITY, PEDIATRICS (1978)
INTERNSHIP, U.C. SAN FRANCISCO, PEDIATRICS (1976)
M.D., U.C. SAN DIEGO, MEDICINE (1975)
M.P.H., U.C. BERKELEY, NUTRITION (1974)
B.S., STANFORD UNIVERSITY, BIOLOGY (1970)
Current Research and Scholarly Interests
Study of the interaction and role of nutrients and intestinal growth factors in enhancing intestinal adaptation and allograft viability using animal models for short bowel syndrome and orthtopic intestinal transplantation.
Study of immunosuppression regimens and induction of immune tolerance in intestinal transplantation.
Prenatal treatment of ornithine transcarbamylase deficiency.
Molecular genetics and metabolism
Patients with neonatal urea cycle defects (UCDs) typically experience severe hyperammonemia during the first days of life, which results in serious neurological injury or death. Long-term prognosis despite optimal pharmacological and dietary therapy is still poor. The combination of intravenous sodium phenylacetate and sodium benzoate (Ammonul®) can eliminate nitrogen waste independent of the urea cycle. We report attempts to improve outcomes for males with severe ornithine transcarbamylase deficiency (OTCD), a severe X-linked condition, via prenatal intravenous administration of Ammonul and arginine to heterozygous carrier females of OTCD during labor.Two heterozygote OTCD mothers carrying male fetuses with a prenatal diagnosis of OTCD received intravenous Ammonul, arginine and dextrose-containing fluids shortly before birth. Maintenance Ammonul and arginine infusions and high-caloric enteral nutrition were started immediately after birth. Ammonul metabolites were measured in umbilical cord blood and the blood of the newborn immediately after delivery. Serial ammonia and biochemical analyses were performed following delivery.Therapeutic concentrations of Ammonul metabolites were detected in umbilical cord and neonatal blood samples. Plasma ammonia and glutamine levels in the postnatal period were within the normal range. Peak ammonia levels in the first 24-48h were 53mcmol/l and 62mcmol/l respectively. The boys did not experience neurological sequelae secondary to hyperammonemia and received liver transplantation at ages 3months and 5months. The patients show normal development at ages 7 and 3years.Prenatal treatment of mothers who harbor severe OTCD mutations and carry affected male fetuses with intravenous Ammonul and arginine, followed by immediate institution of maintenance infusions after delivery, results in therapeutic levels of benzoate and phenylacetate in the newborn at delivery and, in conjunction with high-caloric enteral nutrition, prevents acute hyperammonemia and neurological decompensation. Following initial medical management, early liver transplantation may improve developmental outcome.
View details for PubMedID 29396029
The challenges of closing an ileostomy in patients with total intestinal aganglionosis after small bowel transplant
PEDIATRIC SURGERY INTERNATIONAL
2018; 34 (1): 113–16
We present the case of a 14-year-old male with a history of small bowel transplantation for long segment Hirschsprung's disease who underwent Duhamel ileorectal pull-through procedure. In post-transplant, the patient had no restrictions and was not TPN-dependent. To improve his quality of life, he and his family were interested in closing the ileostomy and undergoing pull-through surgery. The complexity of the case includes the presence of an aganglionic rectal segment-a short root of the mesentery due to the small bowel transplant-and significant immunosuppression. At the moment, he is continent, doing well, and has not had any remarkable complications.
View details for PubMedID 29170900
- Adenovirus Hepatic Abscess: A Novel Source of Fever of Unknown Origin in a Pediatric Liver Transplant Recipient DIGESTIVE DISEASES AND SCIENCES 2017; 62 (4): 871-873
Mass cytometry reveals a distinct immunoprofile of operational tolerance in pediatric liver transplantation.
Long-term IS in transplant patients has significant morbidity, poorer quality of life, and substantial economic costs. TOL, defined as graft acceptance without functional impairment in the absence of IS, has been achieved in some pediatric LT recipients. Using mass cytometry, peripheral blood immunotyping was performed to characterize differences between tolerant patients and patients who are stable on single-agent IS. Single-cell mass cytometry was performed using blood samples from a single-center pediatric LT population of operationally tolerant patients to comprehensively characterize the immune cell populations in the tolerant state compared with patients on chronic low-dose IS. Specific T-cell populations of interest were confirmed by flow cytometry. This high-dimensional phenotypic analysis revealed distinct immunoprofiles between transplant populations as well as a CD4(+) TOT (CD4(+) CD5(+) CD25(+) CD38(-/lo) CD45RA) that correlates with tolerance in pediatric LT recipients. In TOL patients, the TOT was significantly increased as compared to patients stable on low levels of IS. This TOT cell was confirmed by flow cytometry and is distinct from classic Treg cells. These results demonstrate the power of mass cytometry to discover significant immune cell signatures that have diagnostic potential.
View details for DOI 10.1111/petr.12795
View details for PubMedID 27781378
Donor-specific antibodies are associated with rejection after intestinal transplant in pediatric patients
LIPPINCOTT WILLIAMS & WILKINS. 2016: S257
View details for Web of Science ID 000436953200400
Mass cytometry reveals NK cell and T cell subsets in pediatric liver transplant patients with acute rejection
LIPPINCOTT WILLIAMS & WILKINS. 2016: S134
View details for Web of Science ID 000436953200212
Adenovirus Hepatic Abscess: A Novel Source of Fever of Unknown Origin in a Pediatric Liver Transplant Recipient.
Digestive diseases and sciences
View details for PubMedID 26856716
Donor Specific Antibodies Are Associated with Rejection After Small Bowel and Multi-Visceral Transplant in Children
LIPPINCOTT WILLIAMS & WILKINS. 2015: S18
View details for Web of Science ID 000368605200030
PRENATAL TREATMENT OF ORNITHINE TRANSCARBAMYLASE DEFICIENCY
ACADEMIC PRESS INC ELSEVIER SCIENCE. 2014: 248
View details for Web of Science ID 000332500200048
Successful treatment of recurrent primary sclerosing cholangitis after orthotopic liver transplantation with oral vancomycin.
Case reports in transplantation
2013; 2013: 314292-?
Primary sclerosing cholangitis (PSC) is a progressive, cholestatic disease of the liver that is marked by inflammation of the bile ducts and damage to the hepatic biliary tree. Approximately 60-70% of patients also have inflammatory bowel disease and progression of PSC can lead to ulcerative colitis and cirrhosis of the liver. Due to limited understanding of the etiology and mechanism of PSC, the only existing treatment option is orthotopic liver transplantation (OLT); however, recurrence of PSC, after OLT is estimated to be between 5% and 35%. We discuss the successful treatment of a pediatric patient, with recurrent PSC, after OLT with oral Vancomycin.
View details for DOI 10.1155/2013/314292
View details for PubMedID 23509657
View details for PubMedCentralID PMC3595721
Toll-Like Receptor 4 Contributes to Small Intestine Allograft Rejection
2010; 90 (12): 1272-1277
Although outcomes for small intestine transplantation (SIT) have improved in recent years, allograft rejection rates remain among the highest of solid organ grafts. The high load of commensal bacteria in the small intestine may contribute through activation of the toll-like receptor (TLR) pathway. In this study, we examine the participation of TLR4 in acute allograft rejection in an orthotopic mouse model of SIT.Wild-type C57Bl/6 (H-2b) or TLR49(-/-) (H-2b) mice were transplanted with syngeneic (C57Bl/6), allogeneic (BALB/c; H-2d), or F1 (BALB/cxC57Bl/6; H-2d/b) vascularized, orthotopic small intestine grafts. Graft recipients were killed on days 2 to 6 posttransplant. Serum cytokines were measured by Luminex, and tissue was obtained for histology and quantitative real-time polymerase chain reaction.BALB/c grafts transplanted into C57Bl/6 recipients exhibited mixed inflammatory infiltrates, destruction of the mucosa, and significant apoptosis. TLR2 and TLR4 transcripts were modestly increased in syngeneic grafts on days 2 and 6 compared with native bowel, whereas TLR2 and TLR4 were significantly increased on days 2 and 6 in allogeneic grafts. Although fully mismatched and F1 grafts were rejected by C57Bl/6 recipients (mean survival time=8.2 and 9.3 days, respectively), graft survival was significantly prolonged in TLR4(-/-) recipients (mean survival time=10.6 and 14.3 days, respectively). Proinflammatory cytokines were markedly reduced in TLR4(-/-) graft recipients.Small intestine graft survival is prolonged in the absence of TLR4, suggesting that gut flora associated with the graft may augment alloimmune responses through TLR4. Thus, the TLR pathway may be a novel therapeutic target for improving SIT allograft survival.
View details for DOI 10.1097/TP.0b013e3181fdda0d
View details for Web of Science ID 000285377100006
View details for PubMedID 21197709
View details for PubMedCentralID PMC3799863
Analysis of clinical variables associated with tolerance in pediatric liver transplant recipients
2010; 14 (8): 976-979
Tolerance has been defined as stable graft function off IMS. We reviewed the data of 369 pediatric liver transplant patients to examine demographic differences that may have a PV of pediatric LT tolerance. Of the 369 patients, 280 patients were stable with detectable blood levels of IMS agents and with good graft function without biopsy proven REJ > 1 yr posttransplantation, 18 patients were noted to be TOL off IMS, 27 patients were taking MIS with drug levels below detectable range by standard laboratory parameters, and 44 patients developed one or more episodes of biopsy proven acute or chronic REJ > 1 yr post-transplantation. Variables, including percentage of biliary atresia, type of transplanted organ, history of EBV infection, patient and donor gender, and ABO blood type mismatch between recipient and donor did not have PV of tolerance. Average age in years was 1.37 ± 1.53 (0.3-4.9) for TOL, 1.14 ± 0.89 (0.4-3.1) for MIS and 3.35 ± 4.45 (0.3-16) for REJ. Age difference of TOL/MIS vs. REJ was significant (p =0.002) and TOL vs. REJ was significant (0.01). Age at the time of transplantation is an important predictor in the development of pediatric LT tolerance.
View details for DOI 10.1111/j.1399-3046.2010.01360.x
View details for Web of Science ID 000285229500007
View details for PubMedID 21108705
Acute Rejection of Small Intestine Allografts Is Associated With Increased Expression of Toll-like Receptors
2010; 42 (7): 2676-2678
Although outcomes after intestinal transplantation have steadily improved owing to advances in immunosuppressive therapy, operative techniques, and postoperative medical management, rejection of the intestinal allograft continues to be a major clinical problem and constitutes the primary reason for graft loss. Although the adaptive immune system has been the major focus of investigation regarding regulation of rejection of the intestinal allograft, the role of the innate immune system has recently become of increased interest. We hypothesized that microbial products of the microflora associated with the intestinal allograft may engage the Toll-like receptor pathway of the innate immune system to potentiate alloimmune responses and rejection of the allograft. To investigate this, we established a murine model for orthotopic intestinal transplantation and allograft rejection. Using this model, we show that the expression of Toll-like receptor 2 is increased 50-fold and the expression of Toll-like receptor 4 is increased 200-fold during rejection of the allograft. We then performed survival studies that showed increased survival of mice, which had the Toll-like receptor knocked out. These preliminary studies suggest an important role for in innate immune system in acute rejection of the small intestinal allografts, and as such represents an emerging and promising area of investigation.
View details for DOI 10.1016/j.transproceed.2010.05.157
View details for Web of Science ID 000281942200052
View details for PubMedID 20832568
T lymphocytes and Its Subsets in Transplanted Small Bowel Treated with Alemtuzumab (Campath-1H)
11th International Symposium on Small Bowel Transplant
MEDIMOND S R L. 2009: 42–47
View details for Web of Science ID 000303378800008
Campath in pediatric intestinal transplantation
11th International Symposium on Small Bowel Transplant
MEDIMOND S R L. 2009: 20–23
View details for Web of Science ID 000303378800003
Treatment of Recurrent Post-transplant Lymphoproliferative Disorder (PTLD) of the Central Nervous System (CNS) with High-dose Methotrexate (HD-MTX)
11th International Symposium on Small Bowel Transplant
MEDIMOND S R L. 2009: 116–121
View details for Web of Science ID 000303378800021
Outcomes of transplantation in children with primary hepatic malignancy
2007; 11 (6): 655-660
HBL and HCC are the most common hepatic malignancies in children. The role of OLT in children with HCC is still a matter of debate. The aim of this study was to review our experience of OLT for HCC. Medical records of patients (<18 yr) who underwent OLT for HCC were reviewed and compared to children who underwent OLT for HBL and for indications other than malignancy. There were 25 patients: HCC (10 cases) and HBL (15 cases). The actuarial patient survival for HCC at one and five yr was 100% and 83.3%, for the HBL group the survival was 86.7% at both one and five yr, and for indications (n=377) other than malignancy the patient survival for pediatric OLT at our center was 87.7% and 84.7% at one and five yr, respectively. The actuarial recurrence free survival at five yr was 83.3% for HCC and 66.8% for HBL. In conclusion, OLT is a good therapeutic modality for children with HCC and HBL.
View details for DOI 10.1111/j.1399-3046.2007.00751.x
View details for Web of Science ID 000249004000015
View details for PubMedID 17663690
Ileoscopic biopsies may be inadequate for rejection surveillance after isolated intestinal transplantation.
WILEY-BLACKWELL. 2007: 97–97
View details for Web of Science ID 000246659800269
Risk factors for small bowel bacterial overgrowth in cystic fibrosis
JOURNAL OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION
2007; 44 (2): 212-218
The purpose of this study was to determine the prevalence of small bowel bacterial overgrowth in patients with pancreatic-insufficient cystic fibrosis (CF) compared with age-matched controls and to identify potential risk factors for small bowel bacterial overgrowth.Fifty patients, 25 pancreatic-insufficient CF study patients (mean age, 17 y) and 25 gastrointestinal clinic control patients (mean age, 15 y), completed a glucose-hydrogen breath test after an overnight fast. Study patients completed a quality-of-life questionnaire modified from the Cystic Fibrosis Questionnaire. The medical history of each patient was compared with breath test results. A positive breath test was defined as a fasting hydrogen > or =15 ppm or a rise of > or =10 ppm hydrogen over baseline during the test.The prevalence of positive breath tests was higher in the CF study group (56%) than in the control group (20%) (P = 0.02). The mean fasting hydrogen levels of patients in the study and control groups were 22 and 5 ppm (P = 0.0001). The mean questionnaire scores were not significantly different between breath test-positive and -negative study patients. The use of azithromycin was associated with an increased risk of a positive breath test. Use of laxatives and inhaled ipratropium was associated with a decreased risk of a positive breath test.Patients with CF were more likely to have elevated fasting hydrogen levels compared with controls. This suggests a high prevalence of small bowel bacterial overgrowth in CF patients. Medications commonly used by CF patients may influence intestinal health.
View details for Web of Science ID 000243851900011
View details for PubMedID 17255834
Pediatric intestinal transplantation at Packard children's hospital/Stanford University medical center: Report of a four-year experience
9th International Symposium on Small Bowel Transplantation
ELSEVIER SCIENCE INC. 2006: 1716–17
We report a 4-year experience of a new program in pediatric intestinal transplantation. Among 50 children referred for evaluation, 27 were listed for transplantation. Two children originally listed for combined liver/small bowel transplant were changed to isolated intestinal transplant as rehabilitation efforts resulted in full recovery of hepatic function. Eighteen children received 18 grafts: 12 liver/intestine, 5 isolated intestine, and 1 multivisceral. Mean age at transplant was 3.6 year with 75% of patients aged 0 to 2 years. Five listed children died while waiting and four were still on the list. Immunotherapy included antithymocyte globulin induction and tacrolimus, sirolimus, and prednisone maintenance. At 1 year, patient and graft survivals were 75% and 67%, respectively. For isolated intestine, 1 year survivals were 100% and 75%, while for combined liver/intestine, they were 71% for both. Enteral autonomy is 100% with total parenteral nutrition stopping by 35.8 days (mean). We had two patients develop posttransplant lymphoproliferative disorder and three, exfoliative rejection, one of whom recovered completely. In conclusion, our program in pediatric intestinal transplantation has become well established with a high proportion of smaller/younger children receiving grafts. Outcomes achieved levels expected based on The Intestinal Transplant Registry and UNOS criteria, which were better than expected for isolated intestinal transplants and achievement of enteral autonomy.
View details for DOI 10.1016/j.transproceed.2006.05.038
View details for Web of Science ID 000240051700022
View details for PubMedID 16908259
Management of Esophageal recessive dystrophic strictures in children with epidermolysis bullosa
JOURNAL OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION
2002; 34 (5): 535-541
Recessive dystrophic epidermolysis bullosa is a rare, genetically transmitted skin disorder characterized by blister formation and scarring in response to minor trauma. One of the most debilitating features of the disease is the development of esophageal strictures, which produces profound dysphagia, exacerbating an already highly compromised nutritional status common to these patients. Due to the extreme fragility of epithelial surfaces, the optimal therapeutic approach to esophageal strictures in this setting has not been established.We have developed an approach to treatment of esophageal strictures in children with epidermolysis bullosa combining upper endoscopy using small caliber endoscopes, endotracheal intubation, and fluoroscopically assisted balloon dilatation. We report our experience using this technique in 22 children who have undergone a total of 109 dilatations.Upper endoscopy, endotracheal intubation, and balloon dilatation were well tolerated by even very young children with epidermolysis bullosa. Dysphagia was markedly reduced post-procedure, permitting resumption of normal diet for age, including solids, within six hours of the procedure. Post-procedure recovery has been rapid and does not require admission to the hospital. Complications have been infrequent, minor, and limited to the first year of our experience. The mean interval between dilatations for all children is 11 months. All children have gained weight, and have not required steroids or phenytoin.Balloon dilatation is a safe and effective therapy for esophageal strictures in children with recessive dystrophic epidermolysis bullosa. Limited upper endoscopy and endotracheal intubation are well tolerated by these children. This approach should be considered as primary therapy in this clinical setting.
View details for Web of Science ID 000176111400012
The role of growth hormone in adaptation to massive small intestinal resection in rats
2001; 49 (2): 189-196
The residual small bowel undergoes profound adaptive alterations after surgical resection. GH is considered to have a role in regulation of these adaptive changes, but its precise role is unknown. We investigated the role of GH by studying the response to intestinal resection in rats with isolated GH deficiency. Spontaneous dwarf rats, a strain of rats with congenital isolated GH deficiency, underwent 60% resection of the small intestine and parameters of the response of the intestinal remnant were compared with age-matched GH-deficient rats undergoing transection, GH-normal rats undergoing 60% resection, and nonmanipulated GH-normal rats. Deficiency of GH did not inhibit hyperplasia of the mucosal mass of the intestinal remnant, indicating that GH is not required for regulation of this aspect of the adaptive response. However, GH deficiency resulted in lack of accumulation of mucosal protein, including lack of accumulation of digestive hydrolases. In addition, GH deficiency resulted in alterations in processing of digestive hydrolases of the distal intestine, indicating that GH may have region-specific effects on small intestinal function. We conclude that GH is required for the normal expression of specific components of the adaptive response to massive small intestinal resection, but not for all aspects. The aspects that require GH appear to involve protein synthesis and processing.
View details for Web of Science ID 000166686000010
View details for PubMedID 11158512
Paediatric liver transplantation: Indications, timing and medical complications
1st University-of-California-San-Francisco/Stanford Asia Liver Symposium
WILEY-BLACKWELL PUBLISHING, INC. 1999: S61–S66
Newer surgical techniques and immunosuppressive therapies have resulted in paediatric liver transplantation being available for most children with end-stage liver disease and has resulted in a greater than 80% 5-year survival rate. The most common indications for paediatric liver transplantation are biliary atresia (43%), metabolic disease (13%) and acute hepatic necrosis (11%). For approximately 75% of children with acute hepatic failure, the cause is unknown. Timing of liver transplantation not only affects survival rate, but may influence neurodevelopmental outcome. Fortunately, numerous types of donors, such as reduced-sized, living related or unrelated and blood-type mismatched, have reduced the mortality of children who are waiting for liver transplantation. However, the mortality and morbidity before and after liver transplantation remain high for children who have fulminant hepatic failure or are less than 5 months of age at the time of transplantation. The principle medical complications after liver transplantation are rejection and infection. Although use of newer immunosuppressive regimens has reduced the rate of rejection, Epstein-Barr virus infection with associated lymphoproliferative disorder remains the principle cause for morbidity and mortality after the initial 3 months post-liver transplant.
View details for Web of Science ID 000081033600013
View details for PubMedID 10382641
Long-term outcomes in pediatric liver recipients: comparison between cyclosporin A and tacrolimus.
1999; 3 (1): 22-26
In recent years, tacrolimus (FK506, TAC) has been increasingly utilized in liver transplantation. However, long-term risks and benefits as compared with conventional cyclosporin A (CsA) have not been fully elucidated. This retrospective study examined the potential outcome differences between TAC- and CsA-based immunosuppressive therapy in pediatric liver transplant recipients. From March 1988 to December 1996, 218 children (aged 0.1-17 yr) underwent 238 orthotopic liver transplantations; 58.7% (128/218) were under 2 yr of age at time of transplant. Initially, the maintenance immunosuppressive regimen consisted of CsA and prednisone, with antilymphocytic preparations (MALG, ATGAM, and OKT3) as induction therapy. Subsequently, TAC was used first as rescue therapy for steroid refractory rejection in CsA patients and then as maintenance immunosuppression. Fifty-seven out of the 147 CsA patients were converted to TAC for various reasons while 71 patients were placed on TAC as primary maintenance immunosuppression. 62.6 per cent (92/147) of liver recipients on CsA experienced at least one biopsy-proven acute rejection episode as compared to 50.7% (36/71) for TAC patients (p = 0.09); likewise, 34% (50/147) of CsA patients had more than one episode of rejection vs. 18.3% (13/71) for patients on TAC (p < 0.02). Rejection was the reason for conversion from CsA to TAC in 29 of 57 patients. Conversely, 19.0% (28/147) of CsA patients had to be switched to TAC for reasons not related to rejection (i.e. side-effects). The overall incidence of histologically proven chronic rejection was 7.8% (17/218). 10.9 per cent (16/147) of the children who were on CsA initially developed chronic rejection, which was significantly higher compared with one of 71 TAC recipients (p < 0.02). Of these 16 CsA patients with chronic rejection, 50.0% (8/16) underwent retransplantation for graft failure (mean interval from time of diagnosis of chronic rejection to re-transplant, 4.0 months; range 1-8 months), whereas the TAC patient has remained clinically stable with normal liver function tests after 23 months of follow-up. One year after liver transplantation, 72.8% (107/147) of CsA patients were still on steroids (mean dosage 0.20 mg/kg/d), as compared to 42.3% (30/71) of the TAC patients (mean dosage 0.14 mg/kg/d). The incidence of post-transplant lymphoproliferative disorder (PTLD) in Epstein-Barr virus (EBV)-infected patients was 2.2% (2/90), 7.0% (5/71) and 12.3% (7/57) for CsA, primary and TAC-converted groups, respectively. The overall incidence of PTLD was 6.9% (15/218). In summary, pediatric liver transplant recipients treated with TAC as primary maintenance immunosuppressive medication experienced significantly fewer episodes of rejection; especially chronic rejection, which lead to graft loss. However, the trade-off is a potential increased incidence of EBV-related PTLD in these patients.
View details for PubMedID 10359027
Liver transplantation at Stanford University Medical Center.
Because of the unique demographics of our patient population, we have had the opportunity to dedicate further studies of the management of hepatitis B and hepatitis C. We have experienced a very low HBV recurrence rate with the use of HBIG in patients transplanted for hepatitis B. Investigations, including the use of new antiviral agents, and the development of approaches to minimize or abrogate disease recurrence such as lower levels of immunosuppression are ongoing. Using a standardized approach to the proper evaluation and selection of patients for liver transplantation with alcoholic liver disease or other liver diseases with coexistent alcohol abuse, we report favorable long-term results in these patients. We have reviewed our results and our approach to the management of EBV and posttransplant lymphoproliferative disorder. There is a firm commitment in our laboratories and outpatient clinics to the investigation of disease prevention, reliable detection and screening methods, and treatment modalities for EBV-related disease. We have addressed specific technical considerations to pediatric liver transplant and have discussed unique aspects of postoperative management in these patients. One-third of the transplants performed at Stanford are in children, 42% of whom are less than one year old. Results with our pediatric transplant recipients compare favorably with those of our adult recipients with patient and graft survival rates approaching 90% at one year and exceeding 80% at 46 months for both groups. As a response to the limited organ supply, we have extended our criteria for suitable donors. Most notably, we have utilized older donors and grafts with significant microsteatosis and have observed good results with these grafts as long as ischemia time is minimized. We have also successfully used reduced size grafts for our pediatric patients with good results and are continuing to expand the use of living-related partial grafts and split allografts.
View details for PubMedID 10503106
Regulation of postnatal intestinal maturation by growth hormone: Studies in rats with isolated growth hormone deficiency
1996; 40 (1): 88-93
During the 3rd wk of postnatal life in the rat, dramatic maturational changes occur in the structure and function of the small intestine, enabling the animal to make the transition from milk to solid food. To investigate the role of GH in the regulation of this complex process, we studied postnatal intestinal maturation in the spontaneous dwarf rat, a strain of Sprague-Dawley rats with an autosomal recessive mutation in the GH gene resulting in complete but isolated GH deficiency. GH-deficient and GH-normal littermates were studied at d 7 and 14 (suckling) and d 23 (postweaned). The body weight of GH-deficient animals was inhibited by 60% at each age. Longitudinal growth of the small intestine was not inhibited, suggesting that longitudinal small bowel growth is independent of GH regulation. Mucosal cell mass was significantly lower in GH deficiency at all ages studied, and digestive hydrolase capacity per cm of intestine was significantly lower in GH-deficient postweaned animals. However, epithelial cell mass increased markedly in association with weaning and the maturation of lactase, sucrase, and aminooligopeptidase proceeded normally in GH deficiency. These data suggest that, although GH is not required for normal postnatal intestinal maturation, the mucosal epithelial hypoplasia found in GH-deficient animals suggests that GH or GH-dependent factors act as an intestinal mucosal growth factor whose function is to promote the homeostatic or steady-state regulation of mucosal epithelial growth.
View details for Web of Science ID A1996UT55900016
View details for PubMedID 8798252
REGULATION OF THE ONTOGENIC AND REGIONAL EXPRESSION OF INTESTINAL AMINOOLIGOPEPTIDASE
JOURNAL OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION
1994; 18 (1): 1-8
Aminooligopeptidase (AOP) is the predominant peptidase in the small intestinal epithelium. During postnatal development in the rat, characteristic ontogenic and regional patterns of AOP activities become established. To investigate the molecular mechanisms regulating the maturational changes in AOP activity, we compared AOP synthesis and assembly in the jejunum of suckling (14-day-old) and weaned (28-day-old) rats. AOP synthesis was assessed in vivo by intraperitoneal labeling with [35S]methionine. Both AOP activity and AOP synthesis doubled at weaning, while its posttranslational processing remained unaltered. To examine the mechanisms responsible for generating the regional differences in AOP activity in weaned rats, we contrasted the de novo synthesis, kinetic properties, total immunoreactive protein, and degradation of the jejunal and ileal peptidases. Although AOP catalytic activity was significantly greater in the jejunum than in the ileum, its synthesis rate and substrate affinity (Km) were identical at both sites. However, the ileal peptidase was degraded more rapidly than the jejunal enzyme (t1/2 = 4 and 10 h, respectively). In summary, our data show that increased synthesis accounts for the ontogenic rise in intestinal AOP activity but that altered enzyme turnover produces the jejunal-ileal gradient in AOP activity in weaned rats. Thus the ontogenic and regional expressions of intestinal AOP are defined by transcriptional/translational and posttranscriptional regulatory mechanisms, respectively.
View details for Web of Science ID A1994MP53400001
View details for PubMedID 8126606
MATURATION OF JEJUNOILEAL GRADIENTS IN RAT INTESTINE - THE ROLE OF INTRALUMINAL NUTRIENTS
BIOLOGY OF THE NEONATE
1992; 62 (5): 351-362
Jejunoileal gradients of intestinal function are thought to be established during the third week of life in the rat when postnatal intestinal maturation occurs. In order to investigate the normal development of jejunoileal gradients and whether either the absence of intraluminal nutrients or the form in which they are provided affected the development of jejunoileal gradients, gradients for mucosal DNA, protein, lactase and sucrase were studied in suckling rats undergoing normal weaning and compared to gradients in rats receiving no intraluminal nutrients or rats receiving nutrients in elemental form. In suckling animals, preexisting jejunoileal gradients for DNA and protein persisted through the weaning period, gradients for lactase formed by rapid decline of ileal function and sucrase gradients formed by rapid increase in jejunal activities. Intraluminal nutrients in elemental form resulted in the formation of jejunoileal gradients similar to those in intestines of normally weaned rats. The lack of intraluminal nutrients resulted in no qualitative differences in the expression of jejunoileal gradients for sucrase, but provision of elemental nutrients resulted in increased jejunoileal differences for this enzyme. The lack of intraluminal nutrients resulted in no gradients for DNA, less pronounced jejunoileal differences for protein and delayed maturational decline of ileal lactase which prevented development of jejunoileal gradients for the enzyme. These studies indicate that the formation of jejunoileal gradients in the maturing rat intestine for the parameters investigated require intraluminal nutrients regardless of the form in which they are provided for their normal expression.
View details for PubMedID 1467373
ONTOGENY OF INTESTINAL LACTASE - POSTTRANSLATIONAL REGULATION BY THYROXINE
AMERICAN JOURNAL OF PHYSIOLOGY
1992; 263 (4): G538-G543
To assess the molecular mechanisms underlying the regulation of lactase ontogeny by thyroxine (T4), we performed an in vivo study of lactase catalytic activity, synthesis, subunit structure, degradation, and enterocyte migration rates in propylthiouracil-induced hypothyroid rat pups, hypothyroid pups injected with T4, and normally weaned rats. Although lactase catalytic activity remained elevated in the hypothyroid rats and declined normally in the other two groups, lactase synthesis was constant among the groups. Lactase subunit structure was identical in normally weaned and T4-injected animals, but the 100-kDa moiety, characteristic of weaned rats, was absent in the hypothyroid pups. The turnover of lactase enzyme was more rapid in euthyroid and T4-injected rats than in hypothyroid animals (t1/2 = 17, 20, and 30 h, respectively). In addition, enterocyte migration was accelerated in the T4-injected rats and reduced in the hypothyroid group compared with controls. However, transit rate was not directly related to lactase activity. Our results suggest that T4 regulates lactase ontogeny by posttranslational mechanisms that include altered processing and increased degradation of the lactase enzyme.
View details for Web of Science ID A1992JU80500070
View details for PubMedID 1415712
ALTERATIONS IN POSTNATAL INTESTINAL FUNCTION DURING CHRONIC HYPOXEMIA
1992; 31 (3): 234-238
Growth failure is a major complication of chronic hypoxemia, as seen in infants and children with cyanotic congenital heart disease. To determine whether chronic hypoxemia during infancy affects the gastrointestinal tract, we examined small intestinal growth and digestive enzyme activities in chronically hypoxemic newborn lambs and in age-matched controls. Chronic hypoxemia was produced by placing an inflatable occluder around the main pulmonary artery and performing a balloon atrial septostomy. Aortic oxygen saturation was reduced to 60-74% for 2 wk, after which the small intestine was removed for analysis. During chronic hypoxemia, somatic growth rate was decreased to 60% of control (hypoxemic, 135 +/- 20 versus control, 216 +/- 26 g/d, p less than 0.02). No differences in caloric intake were found (hypoxemic, 129 +/- 4 versus control, 128 +/- 4 kcal/kg/d). Chronic hypoxemia did not alter small intestinal growth, as measured by jejuno-ileal weight, jejuno-ileal length, mucosal weight, or mucosal protein or DNA contents. However, sp act of lactase, the principal disaccharidase of the infant lamb intestine, were significantly decreased (hypoxemic, 0.08 +/- 0.01 versus control, 0.146 +/- 0.03 units of enzyme activity/mg DNA, p less than 0.05), as were the total small intestinal contents of lactase (hypoxemic, 61.7 +/- 7.0 versus control, 120.6 +/- 21.7 units of enzyme activity, p less than 0.01). There also were decreases in specific and total activities of other digestive enzymes such as maltase, amino-oligopeptidase, and alkaline phosphatase in hypoxemic intestine that did not achieve statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)
View details for Web of Science ID A1992HF34600007
View details for PubMedID 1561008
MECHANISM OF MATURATIONAL DECLINE OF RAT INTESTINAL LACTASE PHLORIZIN HYDROLASE
1992; 282: 107-113
The maturational decline in lactase-phlorizin hydrolase (LPH) activity was studied in groups of young rats ranging from suckling to early post-weaned states. Associated maturational increases in sucrase-isomaltase (SI) and maltase-glucoamylase (MG) activities were also examined as a comparison. Over this time period changes in cellular concentrations of the three enzymes were observed, reflecting corresponding changes in enzyme activities. Synthesis patterns accompanying these maturational changes in concentration were examined using labelled leucine as a marker. Synthesis of LPH was found to be maintained at constant rates independent of the maturation-associated decline in its concentration, whereas the increases in cellular concentrations of SI and MG were due to accelerated synthesis of the enzyme. Turnover of LPH, based on both the fractional synthesis rate and the disappearance rate of labelled leucine from prelabelled LPH pools, was increased in a quantitatively similar way to the decline in LPH concentration. These findings are consistent with our earlier proposal that the maturational decline of LPH occurs because of accelerated turnover, without a decrease in its rate of synthesis.
View details for Web of Science ID A1992HF96800015
View details for PubMedID 1540126
ONTOGENY OF MEMBRANE AND SOLUBLE AMINO-OLIGOPEPTIDASES IN RAT INTESTINE
AMERICAN JOURNAL OF PHYSIOLOGY
1992; 262 (1): G178-G184
Intestinal amino-oligopeptidase (AOP) plays an essential role in protein digestion. To characterize its postnatal development, we measured AOP activity in intestinal membrane and cytosolic fractions in suckling and weaned rats, compared the subunit structures of the membrane and soluble enzymes, and assessed the biochemical relationship of these peptidases. At weaning, jejunal membrane AOP activity doubled while soluble AOP activity in the ileum fell abruptly. The maturational increase in the molecular mass of ileal membrane AOP was due to alterations in the N-linked glycosylation of this protein. Ileal membrane and soluble AOP exhibited similar substrate affinities, pH optima, inhibition characteristics, and antigenic epitopes. However, soluble AOP was 25-35 kDa smaller than the membrane enzyme. Peak incorporation of [35S]methionine into ileal brush-border AOP preceded maximal radioactivity in soluble AOP, suggesting that the membrane peptidase is a precursor of the soluble enzyme. We conclude that membrane and soluble AOP are closely related proteins with distinct developmental profiles and that the soluble peptidase may be derived from endocytosis of the membrane enzyme.
View details for Web of Science ID A1992HA74200079
View details for PubMedID 1733264
SYNTHESIS AND ACCUMULATION OF PROTEIN AND CARBOHYDRASES ALONG THE RAT VILLUS COLUMN
JOURNAL OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION
1991; 13 (3): 235-241
Enterocytes of the intestinal mucosa of infant and adult rats continuously proliferate in the crypt, mature as they migrate along the villus column, and are discharged from the villus tip. We examined the synthesis patterns of total protein, lactase-phlorizin hydrolase, sucrase-isomaltase, and maltase-glucoamylase as well as the accumulation of these enzymes in cells during migration along the villus. Labeled leucine was administered intraperitoneally to suckling and young adult rats, and radioactivity was determined in protein and digestive carbohydrase pools of developing villus cells separated sequentially from tip to base of the villus column. The developing cells were found to continuously accumulate protein and carbohydrates as they ascended the villus column. In addition, incorporation of radioactivity into total protein and carbohydrase pools occurred at generally constant rates along the length of the villus. These studies showed that the differentiated enterocyte of both infant and young adult rat intestine exhibits a pattern of continuous growth while migrating the length of the villus column and maintains synthesis of protein and digestive carbohydrates at generally constant rates during this time.
View details for Web of Science ID A1991GK80100001
View details for PubMedID 1791499
PITUITARY REGULATION OF POSTNATAL SMALL INTESTINAL ONTOGENY IN THE RAT - DIFFERENTIAL REGULATION OF DIGESTIVE HYDROLASE MATURATION BY THYROXINE AND GROWTH-HORMONE
1991; 129 (3): 1417-1423
During the third week of postnatal life, dramatic ontogenic changes occur in the morphology and enzymology of the small intestine of the infant rat, enabling the animal to make the transition from milk to solid food. To investigate the roles of T4 and GH in regulation of these changes, infant rats were hypophysectomized on day 6 of life by the transauricular technique. Hypophysectomy resulted in diminution of somatic and intestinal growth as well as abnormal maturation of the disaccharidases lactase, sucrase, and maltase when measured on day 25. Administration of either T4 or GH to hypophysectomized animals resulted in moderately increased intestinal growth, while complete restoration of small intestinal growth resulted from administration of the combination of both hormones. Although T4, GH, or the combination of hormones reduced lactase activities, T4 alone produced normal maturation of sucrase and maltase. Neither hypophysectomy nor hormone replacement affected aminooligopeptidase. The molecular structure of lactase, analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was not altered to a major degree in hypophysectomized animals or animals that received hormone replacement, but minor alterations were evident in sucrase structure in hypophysectomy. These studies indicate that 1) T4 and GH actively participate in postnatal regulation of small intestinal ontogeny; 2) thyroid hormones act directly on developing intestinal tissues to independently produce the normal maturation of the disaccharidases by mechanisms that are not likely to involve alterations in processing of the enzyme-protein; and 3) maturation of aminooligopeptidase is not regulated by pituitary hormones, in distinct contrast to the disaccharidases.
View details for Web of Science ID A1991GD33300040
View details for PubMedID 1874180
ALTERED MATURATION OF SMALL INTESTINAL FUNCTION IN THE ABSENCE OF INTRALUMINAL NUTRIENTS - RAPID NORMALIZATION WITH REFEEDING
AMERICAN JOURNAL OF CLINICAL NUTRITION
1991; 53 (2): 558-561
The absence of intraluminal nutrients during weaning in rats was shown to result in altered intestinal growth and maturation. In this study intestinal length, mucosal weight, DNA, protein, and total disaccharidase activities were significantly lower in animals sustained by intravenous nutrients over the normal weaning age than were normally weaned controls but were greater than preweaning values. Absorptive capacity for sucrose (assessed by hydrogen-gas production) was diminished, directly linking incomplete maturation of sucrase to diminished intestinal function. To determine whether these alterations were permanent, rats previously deprived of intraluminal nutrients over the weaning period were refed. Eight days after refeeding, all variables except total lactase had attained values found in normally weaned age-matched controls, including absorptive capacity for sucrose. Although intestinal growth and maturation is abnormal in the absence of intraluminal nutrients during weaning, the abnormalities are not permanent and are rapidly corrected upon refeeding.
View details for Web of Science ID A1991EU94600027
View details for PubMedID 1899174
ETIOLOGY OF INTESTINAL DAMAGE IN GASTROSCHISIS .2. TIMING AND REVERSIBILITY OF HISTOLOGICAL-CHANGES, MUCOSAL FUNCTION, AND CONTRACTILITY
21ST ANNUAL MEETING OF THE CANADIAN ASSOC OF PAEDIATRIC SURGEONS
W B SAUNDERS CO. 1990: 1122–26
Previous work in the fetal lamb examined the relative effects of amniotic fluid and bowel constriction in the etiology of bowel damage in gastroschisis. The present study used the same model to assess the timing and reversibility of these changes during gestation. Gastroschisis was created at 80 days' gestation, and a tape was placed around the bowel to cause gradual constriction with growth. Lambs were killed at 100 days, 120 days, and term. Bowel damage was assessed using histology, mucosal enzyme activity, and in vitro motility. In an additional "repaired" group, the constrictor was removed at 120 days, a silastic pouch placed over the bowel, and bowel damage assessed at term. Normal fetuses at each gestational age were used as controls. A fibrous peel was observed at all gestational ages. Mucosal villous atrophy and mesenteric venous and lymphatic dilation were mild at 100 and 120 days, but severe at term. These changes were present but mild in repaired animals at term. Mucosal enzyme activity decreased gradually with gestational age; inhibition of maltase activity was maximal at term, and was significantly reversed by repair, whereas inhibition of aminooligopeptidase activity was maximal at 120 days, and was not affected by repair. Protein/DNA, DNA/weight, and protein/weight ratios showed that repaired mucosal cells were significantly more proliferative, smaller, and less mature than control or gastroschisis cells. In vitro motility studies demonstrated a mild decrease in contractility at 100 and 120 days, and a large decrease at term. This deleterious effect at the end of gestation was only partially reversed by repair in utero.(ABSTRACT TRUNCATED AT 250 WORDS)
View details for Web of Science ID A1990EH58400005
View details for PubMedID 2148773
INTESTINAL LACTASE IN THE NEONATAL RAT - MATURATIONAL CHANGES IN INTRACELLULAR PROCESSING AND BRUSH-BORDER DEGRADATION
JOURNAL OF BIOLOGICAL CHEMISTRY
1990; 265 (26): 15889-15893
The mechanism of decline in the catalytic activity of intestinal lactase during neonatal maturation has not been defined, but a shift in the lactase subunit synthesis from an active 130-kDa subunit to an inactive 100-kDa species has now been noted in the adult rat (Quan, R., Santiago, N. A., Tsuboi, K. K., and Gray, G. M. (1990) J. Biol. Chem. 265, 15882-15888). The subunit structure, synthesis, intracellular assembly, and subsequent degradation of lactase from the brush-border surface membrane was examined in 15-day-old pre-weaned and 30-day-old post-weaned intact rats. Lactase was labeled intraintestinally with [35S]methionine, isolated from Triton-solubilized membranes with monospecific polyclonal anti-lactase, and analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. The protein-stained gel revealed subunits of 225 and 130 kDa, the latter species predominating in both the pre- and post-weaned state. The distinct adult-type 100-kDa moiety was present in post-weaned animals while only a trace of a slightly larger (approximately 110 kDa) species was observed in pre-weaned animals. Quantitation of radioactivity in newly synthesized lactase revealed an increasing prominence of the 100-kDa species in post-weaned rats (130/100 incorporation ratio: pre-weaned 6.2; post-weaned 3.3). Accumulation of newly labeled lactase in brush-border membranes after intraperitoneal [35S]methionine labeling was similar in both groups at 3 h. Despite these comparable rates of lactase synthesis, assembly and insertion in the pre- and post-weaned state, subsequent removal of the 130-kDa unit was more rapid in post-weaned animals (t1/2 = 11 h; pre-weaned t1/2 = 37 h). In intact rats, the neonatal maturational decline in lactase catalytic activities involves both a shift to production of the inactive 100-kDa subunit and increased membrane surface degradation of the active 130-kDa subunit.
View details for Web of Science ID A1990DY96400085
View details for PubMedID 2118533
HEPATIC COPPER-METABOLISM IN A MOUSE MODEL FOR MENKES KINKY HAIR SYNDROME
1990; 27 (5): 492-496
Menkes' kinky hair syndrome (KHS) is a lethal x-linked neurodegenerative disorder of copper metabolism, with low serum copper concentrations, tissue-specific copper sequestration, and decreased activities of cuproenzymes in a number of cell types. Although liver copper accumulation is abnormal in KHS, the actual defect in hepatic copper metabolism has not been elucidated. Our studies of liver copper metabolism were conducted in the mottled (blotchy) mouse, an animal model of KHS. After implantation of central venous and biliary catheters in both blotchy and control mice, we measured biliary copper excretion, hepatic copper uptake, and tissue copper contents over an 8-h period after i.v. bolus administration of radioactive 64Cu. Under the experimental conditions used, bile flow and biliary bile acid excretion were held constant, and control and blotchy hepatic 64Cu concentrations were similar in the face of the expected differential in control and mutant kidney 64Cu contents. Biliary excretion of radiocopper was 24.7 +/- 1.5% of injected 64Cu over 8 h in control animals, whereas heterozygotes excreted 6.5 +/- 1.3% and a single hemizygote excreted less than 2%. The pattern of biliary copper excretion was different, with sharp increase and steady decline in control biliary 64Cu excretion but consistently low excretion in mutant mice. No differences were observed in control or mutant hepatic uptake of 64Cu. These data show a reduced biliary excretion of copper in the blotchy mouse, in the absence of a defect in hepatic copper uptake. We suggest that defective copper transport from hepatocyte to bile represents the hepatic expression of the mottled mutation and speculate that a similar defect occurs in human KHS.(ABSTRACT TRUNCATED AT 250 WORDS)
View details for Web of Science ID A1990DA90000014
View details for PubMedID 2345676
AN EVALUATION OF FOOD GROUP INTAKES BY MEXICAN-AMERICAN CHILDREN
JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION
1990; 90 (3): 388-393
Food group daily servings were examined for 3,436 children who participated in the Mexican-American portion of the 1982-1983 Hispanic Health and Nutrition Examination Survey (HHANES). Mean daily servings of 40 foods and food groups were calculated for four age groups: 1 to 2 years, 3 to 5 years, 6 to 11 years, and 12 to 17 years. The HHANES food servings data were combined into four major groups and compared with recommended servings for children. Mean daily servings of the milk group exceeded the recommended two to three servings for younger children but were low for teenagers. Meat group servings (including eggs and nuts/legumes) exceeded the recommended two daily servings for all age groups, whereas bread group intakes averaged 70% to 80% of a recommendation of four servings but only half of a recommendation of six servings. Intakes of fruits and vegetables were lowest, averaging only 33% to 47% of a recommended four servings, or 26% to 38% of a recommended five servings. Servings of all four groups were lowest for teenagers. A dietary score, based on the number of servings from each of the four groups, was developed for each child. Mean dietary scores ranged from 55% (teenagers) to 70% (toddlers and preschoolers) of the recommended score. According to these analyses, dietary guidance for Mexican-American children should focus on increasing intakes of fruits and vegetables and on encouraging more nutritious food choices by teenagers.
View details for Web of Science ID A1990CT21400005
View details for PubMedID 2307815
REGULATION OF INTESTINAL ONTOGENY BY INTRALUMINAL NUTRIENTS
JOURNAL OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION
1990; 10 (2): 199-205
Major events in gastrointestinal ontogeny occur in the infant rat in association with weaning, resulting in striking alterations in small intestinal structure and function. Although the dietary changes attendant to weaning are not essential for the initiation of these events, dietary nutrients have been shown to participate in the maturation of some intestinal parameters. In order to define more precisely the role of intraluminal nutrients in the regulation of small intestinal ontogeny, a longitudinal study was conducted using a unique animal model in which intraluminal nutrients were excluded from the intact maturing intestine in vivo throughout the entire weaning period without major compromise in nutritional status. The absence of intraluminal nutrients over the weaning period resulted in diminished lengthening and accretion of mucosal mass, suggesting a slower rate of intestinal growth. Lower mucosal DNA, protein, and mitotic indices in intestines of animals receiving no intraluminal nutrients suggested that the lack of intraluminal nutrients resulted in the blunting of the striking increases in cellular proliferation normally exhibited by the developing intestinal mucosa at this time. Maturation of intestinal lactase-phlorizin hydrolase and maltase-glucoamylase was not affected by the absence of intraluminal nutrients. Although the appearance of sucrase-isomaltase was not altered by the absence of intraluminal nutrients, activity levels rose to only 50% of control levels. These data suggest that during this period of rapid intestinal maturation, intestinal growth is more dependent upon intraluminal nutrients than are the characteristic enzymic alterations normally expressed during this period.(ABSTRACT TRUNCATED AT 250 WORDS)
View details for Web of Science ID A1990CM93700010
View details for PubMedID 2303970
PITUITARY REGULATION OF DIGESTIVE ENZYME MATURATION AND STRUCTURE IN THE NEONATAL RAT
SLACK INC. 1990: A173–A173
View details for Web of Science ID A1990CF63600999
PITUITARY REGULATION OF DEVELOPMENT OF JEJUNOILEAL DIFFERENCES IN MATURING RAT INTESTINE
SLACK INC. 1990: A172–A172
View details for Web of Science ID A1990CF63600991
HUMAN INTESTINAL LACTASE-PHLORIZIN HYDROLASE - ISOLATION AND PREPARATION OF A SPECIFIC ANTISERUM
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
1989; 164 (1): 94-101
Human intestinal lactase-phlorizin hydrolase (lactase) was selectively isolated with monospecific polyclonal antibodies to rat lactase. In addition to their immunologic similarities indicated by this isolation, human and rat lactase have similar kinetic characteristics but different subunit structure when analyzed by gel electrophoresis under reducing conditions. Rabbits immunized by injecting human lactase complexed with anti-rat lactase produced specific antibodies to human lactase that exhibited little cross-reactivity to the rat enzyme. The simple single-step procedure allows isolation of human lactase in high purity from small biologic samples and preparation of specific antisera to the human enzyme.
View details for Web of Science ID A1989AV34300015
View details for PubMedID 2508642
DIETARY CHO AND STIMULATION OF CARBOHYDRASES ALONG VILLUS COLUMN OF FASTED RAT JEJUNUM
AMERICAN JOURNAL OF PHYSIOLOGY
1989; 256 (1): G158-G165
Adult rats when fed a high carbohydrate diet of 70% sucrose or glucose for 24 h following a 4-day fast showed increased concentrations of intestinal sucrase-isomaltase (EC 188.8.131.52, EC 184.108.40.206) and maltase-glucoamylase (EC 220.127.116.11) but not lactase-phlorizin hydrolase (EC 18.104.22.168, EC 22.214.171.124). The concentration increases of these enzymes were accompanied by corresponding acceleration of their synthesis rates. Contrary to earlier studies by others, suggesting that upper villus cells in the fasted intestine are unresponsive to stimulation of sucrase activity by refeeding a high-sucrose diet, the concentration increases of both sucrase-isomaltase and maltase-glucoamylase were seen to occur in cells all along the length of the villus column. The earlier studies differed from the present study by basing enzyme assays relative to protein rather than the DNA content of villus cell fractions. We have shown that villus cells increase their protein content severalfold while migrating to villus tip, providing the basis for the difference between earlier and the present findings. Further evidence that stimulation of sucrase-isomaltase and maltase-glucoamylase by high carbohydrate is not restricted to the crypt and lower villus region was obtained by the finding that their synthesis rates appeared to be equally stimulated along the length of the villus column.
View details for Web of Science ID A1989R955100077
View details for PubMedID 2492155
RELATIONSHIP BETWEEN BREATH AND TOTAL-BODY HYDROGEN EXCRETION RATES IN NEONATES
JOURNAL OF PEDIATRIC GASTROENTEROLOGY AND NUTRITION
1988; 7 (4): 554-558
Our study examined the relationship of H2 excreted in breath to total body H2 excreted by neonates. We report simultaneously measured end-tidal H2 concentrations, plus breath H2 and total body H2 (breath H2 plus flatus H2) excretion rates in 10 neonates. End-tidal H2 concentrations varied from 2.4 to 192 ppm. Breath H2 excretion rates ranged from 0.20 to 6.5 and total body H2 excretion rates from 0.29 to 15.0 ml/h. The fractional breath H2 excretion in these infants was 48% (range 33-69%), compared with 21% reported in adults. The correlation coefficient for end-tidal derived H2 excretion and directly measured breath H2 excretion rates was 0.95 (p less than 0.001). We conclude that the proportion of total H2 excreted in the breath of neonates is increased compared with adults, suggesting that caution must be exercised when interpreting newborn breath H2 measurements and using adult norms.
View details for Web of Science ID A1988N975500013
View details for PubMedID 3397846
MATURATIONAL PATTERNS OF CARBOHYDRASES IN THE ILEAL REMNANT OF RATS AFTER JEJUNECTOMY AT INFANCY
AMERICAN JOURNAL OF CLINICAL NUTRITION
1988; 47 (5): 868-874
The enteric epithelium of suckling rat undergoes dramatic functional and cytokinetic changes (redifferentiation) with maturation. Ileal epithelial maturation was studied in infant rats subjected to 60% proximal enterectomy at age 10 d in an effort to examine redifferentiation mechanisms. Two months after resection the residual ileal remnant was increased in diameter, weight, total protein, and DNA per unit length compared with ileal segments from control littermates that had laparotomy without resection. The residual ileum demonstrated increased sucrase activity per unit length but was indistinguishable from control ileal segments in activity per unit DNA or villus distribution. Lactase activity was negligible in all segments of the residual intestine. Villus height and crypt depth were increased in the residual ileum with slight increases in cell turnover and cell-migration rates. These results show the presence of an intrinsic program for regulation of ileal epithelial maturation and its resistance to alteration by a major stimulus applied before its expression.
View details for Web of Science ID A1988N242700015
View details for PubMedID 3129930
- BODY PROPORTIONS IN 3 ETHNIC-GROUPS - CHILDREN AND YOUTHS 2-17 YEARS IN NHANES-II AND HHANES HUMAN BIOLOGY 1988; 60 (2): 205-222
RELATIONSHIP BETWEEN BREATH AND TOTAL HYDROGEN EXCRETION RATES IN NEONATES
SLACK INC. 1988: A206–A206
View details for Web of Science ID A1988L516801203
GROWTH ABNORMALITIES IN MEXICAN-AMERICAN CHILDREN IN THE UNITED-STATES - THE NATIONAL-HEALTH AND NUTRITION EXAMINATION SURVEY I-STUDY
1986; 6 (11): 1247-1257
View details for Web of Science ID A1986F386100002
ORAL CORRECTION OF ESSENTIAL FATTY-ACID DEFICIENCY IN CYSTIC-FIBROSIS
JOURNAL OF PARENTERAL AND ENTERAL NUTRITION
1981; 5 (6): 501-504
A combination of pancreatic insufficiency and inadequate caloric intake may produce essential fatty acids (EFA) deficiency in patients with cystic fibrosis. Seventy-five percent of the adolescents and young adults with poor weight gain in our clinic were EFA-deficient by total plasma linoleic acid criteria. Twenty of these patients were placed on an oral hyperalimentation regimen containing 230% of calories required for basal energy expenditure, 40% as fat. Forty percent of these (8/20) achieved normal EFA levels on this diet. Eight of the nonresponding patients were given an additional 5% of their caloric intake as linoleic acid monoglyceride. All who maintained caloric intake achieved normal EFA levels. Normalization of EFA levels was associated with a number of clinical benefits including increase in weight and activity and, in five teenage girls, regulation of menses. The 16 control patients who received standard pancrelipase therapy and nutritional supplements remained fatty acid deficient. We conclude that oral hyperalimentation can restore EFA levels in cystic fibrosis patients if adequate calories are available to provide energy needs.
View details for Web of Science ID A1981MZ06200007
View details for PubMedID 6801283