Sanna Elizabeth Herwald

All Publications

• Label-free monitoring of embolotherapy via catheter electrochemical impedance spectroscopy. Scientific reports Vezeridis, A. M., Herwald, S. E., Paik, K. H., Daniel, B. L., Sze, D. Y. 2024; 14 (1): 21310

  Abstract

  Catheter-based embolization has become a widely adopted minimally-invasive treatment for a broad range of applications. However, assessment of embolization endpoints requires x-ray fluoroscopic monitoring, exposing patients and physicians performing embolization procedures to harmful ionizing radiation. Moreover, x-ray fluoroscopy assessment of embolization endpoints is low sensitivity, subjective, and may not reflect the actual physiology of blood flow reduction, thus providing little oversight of the embolization procedure. Inspired by the observation that the dielectric properties of blood differ from those of fluids injected during the embolization procedure, a customized angiographic catheter was created with embedded electrodes for catheter-based electrochemical impedance spectroscopy as a way to monitor embolization. Real-time electrochemical impedance spectroscopy was performed in a phantom and compared to visual and videographic monitoring. Electrochemical impedance spectroscopy was able to sense endpoints of embolization, including stasis, reflux, and persistent flow. This new technique offers a label-free method of sensing embolization progress with potentially higher sensitivity and reproducibility compared to x-ray, as well as offer substantial reduction in x-ray exposure to patients and physicians.

  View details for DOI 10.1038/s41598-024-71835-z

  View details for PubMedID 39266579

  View details for PubMedCentralID 10249679

• Design and implementation of a cost-effective, open-source, and programmable pulsatile flow system. HardwareX Herwald, S. E., Sze, D. Y., Ennis, D. B., Vezeridis, A. M. 2024; 19: e00561

  Abstract

  The primary objective of this research was to design, implement, and validate a programmable open-source pulsatile flow system to cost-effectively simulate vascular flows. We employed an Arduino-compatible microcontroller combined with a motor driver to control a centrifugal direct current (DC) motor pump. The system was programmed to produce pulsatile flows with an arterial pulse waveform. Validation with Doppler ultrasound and flow measurements confirmed that our Arduino-based system successfully replicated arterial vascular flow. The materials are easily accessible, with a total bill of materials as low as $99. This open-source programmable pulsatile pump platform offers superior cost-effectiveness and adaptability relative to commercial offerings.

  View details for DOI 10.1016/j.ohx.2024.e00561

  View details for PubMedID 39161639

  View details for PubMedCentralID PMC11331932

• Frequent Amplification and Overexpression of PSMA in Basallike Breast Cancer from Analysis of The Cancer Genome Atlas. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Zhou, W., Halder, S., Herwald, S., Ghijsen, M., Shafi, G., Uttarwar, M., Rosen, E., Franc, B., Kishore, S. 2024

  Abstract

  Prostate-specific membrane antigen (PSMA) is frequently overexpressed in nonprostate malignancies. This preclinical study investigated the molecular basis of the application of PMSA-targeting radiopharmaceuticals in breast cancer subtypes. Methods: The somatic copy number status and the transcriptomic and protein expressions of FOLH1 (gene name of PSMA) were analyzed across breast cancer subtypes in 998 patients from The Cancer Genome Atlas dataset. Results: FOLH1 was frequently amplified in basallike breast cancer (BLBC) (32%) compared with luminal and human epidermal growth factor receptor 2-positive subtypes (16% and 17%, respectively; P < 0.01). FOLH1 expression was higher in BLBC (P < 0.001) and was negatively correlated with estrogen-receptor and progesterone-receptor expressions. Consistently, the PSMA protein level was higher in BLBC (P < 0.05). Interestingly, FOLH1 expression was associated with relapse-free and distant metastasis-free survival in patients with BLBC. Conclusion: The BLBC subtype exhibited frequent amplification and overexpression of PSMA, supporting the exploration of PSMA-targeting radiopharmaceuticals in this aggressive breast cancer subtype.

  View details for DOI 10.2967/jnumed.123.266659

  View details for PubMedID 38664014

• Health for All: A Report of the 2020 Association of American Medical Colleges Learn Serve Lead Meeting. Journal of the American College of Radiology : JACR Herwald, S. E., Farooq, A., Balthazar, P., Haines, G. R., Anzai, Y. 1800

  Abstract

  Learn Serve Lead (LSL) is the signature annual conference of the Association of American Medical Colleges (AAMC), which focuses on the most pressing issues facing American medical practice and education. Unsurprisingly, the recent AAMC LSL conference at the end of 2020 centered on the multifaceted impacts of the COVID-19 pandemic and racial inequity upon the medical community. At the LSL meeting, national leaders, practicing physicians from diverse specialties, and medical trainees discussed the impact of these challenges and ongoing strategies to overcome them. These efforts paralleled the AAMC mission areas of community collaborations, medical education, clinical care, and research. Additionally, this focus aligns with the ACR's core purpose: to serve patients and society by empowering members to advance the practice, science, and professions of radiological care. ACR is a member of the AAMC Council of Faculty and Academic Society and seeks to collaborate with other medical specialties to promote interdisciplinary collaboration, contribute to medical education, and voice the value of medical imaging for patient care. We summarize the major insights of this interdisciplinary conference and present tailored recommendations for applying these insights specifically within the radiology community. In addition, we review the parallels between the ACR and the AAMC strategic plans.

  View details for DOI 10.1016/j.jacr.2021.11.007

  View details for PubMedID 35094940

• Computed Tomography-Guided Microwave Ablation of Cystic Renal Cell Carcinoma: Assessment of Technique and Complications. Journal of vascular and interventional radiology : JVIR Zhou, W., Herwald, S. E., Arellano, R. S. 2021; 32 (4): 544–47

  Abstract

  This report evaluates the techniques and complications of microwave ablation of cystic renal cell carcinoma. Five patients with cystic renal cell carcinoma were treated with microwave ablation between October 2015 and June 2020. Medical records were reviewed to evaluate technique and complications. Technical success and primary technique efficacy both were 100%. There were no complications. Mean follow-up time was 18 months (range, 6-36 months). No local recurrence was identified during the follow-up period. Renal function remained stable at 1 month and the last follow-up. Percutaneous microwave ablation is promising for the nonsurgical management of cystic renal cell carcinoma.

  View details for DOI 10.1016/j.jvir.2020.12.021

  View details for PubMedID 33795074

• Inflammatory Pseudotumor Mimics Local Recurrence following a Microwave Ablation of Renal Cell Carcinoma. Journal of vascular and interventional radiology : JVIR Zhou, W., Herwald, S. E., Arellano, R. S. 2021

  View details for DOI 10.1016/j.jvir.2020.12.025

  View details for PubMedID 33526344

• Impact of Body Mass Index on Perioperative Complications and Oncologic Outcomes in Patients Undergoing Thermal Ablation for Renal Cell Carcinoma. Journal of vascular and interventional radiology : JVIR Zhou, W., Herwald, S. E., Uppot, R. N., Arellano, R. S. 2020

  Abstract

  PURPOSE: To determine effect of body mass index (BMI) on safety and cancer-related outcomes of thermal ablation for renal cell carcinoma (RRC).MATERIALS AND METHODS: This retrospective study evaluated 427 patients (287 men and 140 women; mean [SD] age, 72 [12] y) who were treated with thermal ablation for RCC between October 2006 and December 2017. Patients were stratified by BMI into 3 categories: normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), and obese (≥ 30 kg/m2). Of 427 patients, 71 (16%) were normal weight, 157 (37%) were overweight, and 199 (47%) were obese. Complication rates, local recurrence, and residual disease were compared in the 3 cohorts.RESULTS: No differences in technical success between normal-weight, overweight, and obese patients were identified (P= .72). Primary technique efficacy rates for normal-weight, overweight, and obese patients were 91%, 94%, and 93% (P= .71). There was no significant difference in RCC specific-free survival, disease-free survival, and metastasis-free survival between obese, overweight, and normal-weight groups (P= .72, P= .43, P= .99). Complication rates between the 3 cohorts were similar (normal weight 4%, overweight 2%, obese 3%; P= .71).CONCLUSIONS: CT-guided renal ablation is safe, feasible, and effective regardless of BMI.

  View details for DOI 10.1016/j.jvir.2020.07.028

  View details for PubMedID 33308948

• Thermal Ablation of Renal Cell Carcinoma in Morbidly Obese Patients: Assessment of Technical Results, Procedural Safety, and Oncological Outcomes. AJR. American journal of roentgenology Zhou, W., Herwald, S. E., Uppot, R. N., Arellano, R. S. 2020

  Abstract

  Please see the Author Video associated with this article. BACKGROUND. Obesity is a worldwide problem that impacts patient health as well as the morbidity associated with surgical procedures. Thus, morbidly obese patients may not be suitable candidates for curative surgery. For this patient population, thermal ablation may be an effective alternative to nephrectomy. OBJECTIVE. To determine the feasibility, oncological outcomes, and survival of morbidly obese patients with renal cell carcinoma treated with thermal ablation. MATERIALS AND METHODS. A retrospective analysis was performed of 107 patients treated with CT-guided renal ablation for clinical stageT1renal cell carcinoma between February 2005 and December 2017. Patients were stratified into two cohorts on body mass index of ≥ 40 kg/m2 (morbidly obese) and body mass index of 18.5 to 24.9 kg/m2 normal-weight). Anesthetic and radiation dosages, procedure time, residual disease, and local recurrence and adverse events were analyzed between the two groups. Kaplan-Meier statistics evaluated cancer-related outcomes for each group. RESULTS. 34 patients were morbidly, and 73 patients were normal-weight. Morbid obesity was associated with longer procedural duration (p = 0.001), sedative doses (p = 0.002) and radiation exposure (p = 0.001), compared to normal-weight patients. Hematomas were more prevalent in the morbidly obese than normal body mass index patients (p = 0.01), but treatment efficacy and local recurrences were comparable to normal-weight individuals (p = 0.81, p = 0.12, respectively). Cancer-related outcomes were equivalent between the two groups based on five years of imaging observation data. CONCLUSION. CT-guided thermal ablation remains technically feasible, well-tolerated and effective in morbidly obese patients with renal cell carcinoma, with the caveat of increased risk of perinephric hematoma, anesthesia dosage and radiation exposure. CLINICAL IMPACT: CT-guided thermal ablation can be considered a safe and effective treatment for morbidly obese patients with renal cell carcinoma.

  View details for DOI 10.2214/AJR.20.23803

  View details for PubMedID 32755206

• Radiofrequency Ablation, Cryoablation, and Microwave Ablation for T1a Renal Cell Carcinoma: A Comparative Evaluation of Therapeutic and Renal Function Outcomes JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY Zhou, W., Herwald, S. E., McCarthy, C., Uppot, R. N., Arellano, R. S. 2019; 30 (7): 1035–42

  Abstract

  To compare the therapeutic and renal function outcomes of radiofrequency (RF) ablation, cryoablation, and microwave (MW) ablation for treatment of T1a renal cell carcinoma (RCC).A retrospective assessment of 297 patients (mean age 72 years range 24-90 years) with biopsy-proven RCC treated with image-guided percutaneous thermal ablation was performed between October 2006 and December 2016. Mean tumor size was 2.4 cm; mean radius, exophytic/endophytic properties, nearness of tumor to collecting system or sinus, anterior/posterior, hilar tumor touching the main renal artery or vein, and location relative to polar lines; Preoperative Aspects and Dimensions Used for an Anatomical; and c-centrality scores were 6.0, 7.0, and 2.8, respectively. Assessments of adverse events, treatment efficacy, and therapeutic outcomes were performed among RF ablation, cryoablation, and MW ablation. The 2-year disease-free, metastatic-free, and cancer-specific survival rates were tabulated. Estimated glomerular filtration rate was used to assess for treatment related changes in renal function.A total of 297 T1aN0M0 biopsy-proven RCCs measuring 1.2-3.9 cm were treated with computed tomography-guided RF ablation (n = 244, 82%), cryoablation (n = 26, 9%), and MW ablation (n = 27, 9%). There were no significant differences in patient demographics among the 3 groups (P = .09). Technical success rates were similar among the 3 treatments (P = .33). Primary efficacy at 1 month postablation was more likely to be achieved with RF ablation and MW ablation than with cryoablation. At 2 years' follow-up, there was no local recurrence, metastatic progression, or RCC-related death observed in the 3 groups. There was no significant change in estimated glomerular filtration rate among the 3 ablation groups compared with baseline at 2-year follow-up (P = .71).RF ablation, cryoablation, and MW ablation are equivalent at 2 years for treatment of T1a RCC for therapeutic outcome, stability of renal function, and low adverse event rate.

  View details for DOI 10.1016/j.jvir.2018.12.013

  View details for Web of Science ID 000475412000009

  View details for PubMedID 30956075

• Risk Assessment of Chronic Kidney Disease following Microwave Ablation for Stage T1 Renal Cell Carcinoma JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY Zhou, W., Herwald, S. E., Uppot, R. N., Arellano, R. S. 2018; 29 (12): 1685–91

  Abstract

  To assess safety and renal-function outcomes after microwave (MW) ablation of localized stage T1 renal cell carcinoma (RCC).A retrospective review was conducted of 38 patients (28 men; mean age, 69 y; range, 51-88 y) who underwent computed tomography (CT)-guided MW ablation for stage T1N0M0 RCC. Baseline and follow-up renal function surrogates including creatinine level and estimated glomerular filtration rate (eGFR) were statistically compared. Peri- and postoperative complication rates, technical success, and treatment response were also assessed.A total of 44 biopsy-proven stage T1N0M0 RCCs measuring 1.2-6.9 cm (mean, 2.5 cm) were treated, and renal function was measured 1 mo after treatment. Mean eGFRs were 60 mL/min/1.73 m2 at baseline and 59 mL/min/1.73 m2 at 1 month after ablation. At 1-year and last follow-ups, the means of difference were 3.3% (95% confidence interval, -4.4 to 4.3; P = .99) and 3.3% (95% confidence interval, -4.3 to 4.8; P = .91), respectively. The 2-years freedom from eGFR decrease to < 60 mL/min/1.73 m2 was 2% (P = .91). Among the 5 patients (13%) with preexisting stage 4 chronic kidney disease (CKD; eGFR < 30 mL/min/1.73 m2) before ablation, there was no significant postablative onset of decline or CKD upstaging (P = .001). There were no major complications, and 5 patients (13%) had small asymptomatic perinephric hematomas (Society of Interventional Radiology minor complication, class A/B) that were managed conservatively.At 2-year follow-up, CT-guided percutaneous MW ablation is safe and well-tolerated and achieves nephron preservation similar to existing ablative modalities.

  View details for DOI 10.1016/j.jvir.2018.06.021

  View details for Web of Science ID 000453341200009

  View details for PubMedID 30297311

• Image-Guided Thermal Ablation for Non-resectable Recurrence of Renal Cell Cancer Following Nephrectomy: Clinical Experience with Eleven Patients CARDIOVASCULAR AND INTERVENTIONAL RADIOLOGY Zhou, W., Herwald, S. E., Uppot, R. N., Arellano, R. S. 2018; 41 (11): 1743–50

  Abstract

  To assess the feasibility, safety and clinical outcomes of image-guided percutaneous thermal ablation as salvage therapy for local recurrence of renal cell carcinoma (RCC) in patients initially treated surgically with curative intent.A retrospective review of 11 consecutive patients (M/F = 8:3, mean age = 76 years) who underwent computed tomography (CT)-guided thermal ablation for locally recurrent RCC after partial (72%, 8/11) or radical nephrectomy (28%, 3/11) with a mean time to recurrence of 48 months (range 2-156). Assessment of technical success, complication (peri- and post-procedural), oncological outcome and survival analysis were performed. Patient baseline and follow-up renal function surrogates including creatinine level (Cr) and estimated glomerular filtration rate (eGFR) were statistically compared.Eleven biopsy-proven recurrent RCC measuring 1.4-3.9 cm (mean = 2.8 cm) were treated with CT-guided thermal ablation. Technical success was achieved in 100% (11/11) of the cases. There were no major complications except for one (9%) asymptomatic hemorrhage (Clavien-Dindo grade I complication). Complete response, local progression-free and overall survival rate were 91, 91 and 82% during the mean follow-up time of 2.5 years (range 0.1-7.1). Renal function was overall stable without significant change at 1 month and last follow-up (p = 0.21; GFR, p = 0.10; creatinine).Image-guided percutaneous thermal ablation is a feasible, safe and effective for local recurrence after nephrectomy, representing a non-surgical alternative for unresectable disease.

  View details for DOI 10.1007/s00270-018-1976-2

  View details for Web of Science ID 000451930300013

  View details for PubMedID 29721615

• The two transmembrane regions of Candida albicans Dfi1 contribute to its biogenesis BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS Herwald, S. E., Zucchi, P. C., Tan, S., Kumamoto, C. A. 2017; 488 (1): 153–58

  Abstract

  The opportunistic pathogen Candida albicans forms invasive filaments that grow into host tissues during disease. The glycosylated, integral plasma membrane protein Dfi1 is important for invasive filamentation in a laboratory model, and for lethality in murine disseminated candidiasis. However, Dfi1 topology and essential domains for Dfi1 biogenesis were undefined. Sequence analysis predicted that Dfi1 contains two transmembrane regions, located near the N- and C-termini. In this communication, we show that Dfi1 remains an integral membrane protein despite deletion of either predicted transmembrane region, whereas deletion of both regions results in a soluble protein. Additionally, Dfi1 that was properly oriented in the membrane, as indicated by N-linked glycosylation, was observed when either transmembrane region was deleted, but was absent when both transmembrane regions were deleted. Interestingly, deletion of the N-terminal transmembrane region resulted in production of two forms of Dfi1. Most of the protein molecules acquired normal N-linked glycosylation and a smaller population failed to become normally N-linked glycosylated. This defect was reversed by replacement of the N-terminal hydrophobic sequence with one synthetic transmembrane sequence but not another. Finally, microscopy studies revealed that Dfi1 lacking the N-terminal transmembrane region was observed at the cell periphery, where full-length Dfi1 normally localizes, whereas the double-truncation mutant was diffusely intracellular. Therefore, mature Dfi1 protein contains two transmembrane domains which contribute to its biogenesis.

  View details for DOI 10.1016/j.bbrc.2017.04.158

  View details for Web of Science ID 000402587000024

  View details for PubMedID 28483525

  View details for PubMedCentralID PMC5521179

• Anticipated Supply and Demand for Independent Interventional Radiology Residency Positions: A Survey of Department Chairs JOURNAL OF THE AMERICAN COLLEGE OF RADIOLOGY Herwald, S. E., Spies, J. B., Yucel, E. 2017; 14 (2): 242–46

  Abstract

  The first participants in the independent interventional radiology (IR) residency match will begin prerequisite diagnostic radiology (DR) residencies before the anticipated launch of the independent IR programs in 2020. The aim of this study was to estimate the competitiveness level of the first independent IR residency matches before these applicants have already committed to DR residencies and possibly early specialization in IR (ESIR) programs.The Society of Chairs of Academic Radiology Departments (SCARD) Task Force on the IR Residency distributed a survey to all active SCARD members using SurveyMonkey. The survey requested the number of planned IR residency and ESIR positions. The average, minimum, and maximum of the range of planned independent IR residency positions were compared with the average, maximum, and minimum, respectively, of the range of planned ESIR positions, to model matches of average, high, and low competitiveness.Seventy-four active SCARD members (56%) answered at least one survey question. The respondents' programs planned to fill, in total, 98 to 102 positions in integrated IR residency programs, 61 to 76 positions in independent IR residency programs, and 50 to 77 positions in ESIR DR residency programs each year. The ranges indicate the uncertainty of some programs regarding the number of positions.The survey suggests that participating programs will fill sufficient independent IR residency positions to accommodate all ESIR applicants in a match year of average or low competitiveness, but not in a match year of high competitiveness. This suggestion does not account for certain difficult-to-predict factors that may affect the independent IR residency match.

  View details for DOI 10.1016/j.jacr.2016.08.036

  View details for Web of Science ID 000394478300021

  View details for PubMedID 28161025

• Irreversible Electroporation for Treatment of Hepatocellular Carcinoma Adjacent to the Gallbladder JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY Herwald, S. E., Chen, J. H., Arellano, R. S. 2016; 27 (7): 1093–94

  View details for DOI 10.1016/j.jvir.2016.03.008

  View details for Web of Science ID 000379796500023

  View details for PubMedID 27338501

• The game theory of Candida albicans colonization dynamics reveals host status-responsive gene expression BMC SYSTEMS BIOLOGY Tyc, K. M., Herwald, S. E., Hogan, J. A., Pierce, J. V., Klipp, E., Kumamoto, C. A. 2016; 10: 20

  Abstract

  The fungal pathogen Candida albicans colonizes the gastrointestinal (GI) tract of mammalian hosts as a benign commensal. However, in an immunocompromised host, the fungus is capable of causing life-threatening infection. We previously showed that the major transcription factor Efg1p is differentially expressed in GI-colonizing C. albicans cells dependent on the host immune status. To understand the mechanisms that underlie this host-dependent differential gene expression, we utilized mathematical modeling to dissect host-pathogen interactions. Specifically, we used principles of evolutionary game theory to study the mechanism that governs dynamics of EFG1 expression during C. albicans colonization.Mathematical modeling predicted that down-regulation of EFG1 expression within individual fungal cells occurred at different average rates in different hosts. Rather than using relatively transient signaling pathways to adapt to a new environment, we demonstrate that C. albicans overcomes the host defense strategy by modulating the activity of diverse fungal histone modifying enzymes that control EFG1 expression.Based on our modeling and experimental results we conclude that C. albicans cells sense the local environment of the GI tract and respond to differences by altering EFG1 expression to establish optimal survival strategies. We show that the overall process is governed via modulation of epigenetic regulators of chromatin structure.

  View details for DOI 10.1186/s12918-016-0268-1

  View details for Web of Science ID 000370950700001

  View details for PubMedID 26927448

  View details for PubMedCentralID PMC4772284

• Candida albicans Niche Specialization: Features That Distinguish Biofilm Cells from Commensal Cells CURRENT FUNGAL INFECTION REPORTS Herwald, S. E., Kumamoto, C. A. 2014; 8 (2): 179–84

  Abstract

  The fungus Candida albicans is a frequent commensal colonizer of the human gastrointestinal (GI) tract, but is also an opportunistic pathogen. This review explores features that distinguish the colonizing and pathogenic forms of C. albicans. Candida albicans in a biofilm is used as an example of a pathogenic form of the organism, because biofilms are a common feature of device-associated C. albicans infections. Biofilms (complex, sessile communities of cells) have been the subject of several large-scale gene expression studies. Biofilms and commensal C. albicans colonizing the murine GI tract show a variety of differentially expressed genes. Cell surface proteins encoded by these differentially expressed genes are especially attractive as targets for new clinical prevention, diagnosis, or treatment tools that are specific for C. albicans in its pathogenic biofilm state.

  View details for DOI 10.1007/s12281-014-0178-x

  View details for Web of Science ID 000219664900008

  View details for PubMedID 24839528

  View details for PubMedCentralID PMC4019406

• Structure and Substrate Specificity of the Pyrococcal Coenzyme A Disulfide Reductases/Polysulfide Reductases (CoADR/Psr): Implications for S-0-Based Respiration and a Sulfur-Dependent Antioxidant System in Pyrococcus BIOCHEMISTRY Herwald, S., Liu, A. Y., Zhu, B. E., Sea, K. W., Lopez, K. M., Sazinsky, M. H., Crane, E. J. 2013; 52 (16): 2764–73

  Abstract

  FAD and NAD(P)H-dependent coenzyme A disulfide reductases/polysulfide reductases (CoADR/Psr) have been proposed to be important for the reduction of sulfur and disulfides in the sulfur-reducing anaerobic hyperthermophiles Pyrococcus horikoshii and Pyrococcus furiosus; however, the form(s) of sulfur that the enzyme actually reduces are not clear. Here we determined the structure for the FAD- and coenzyme A-containing holoenzyme from P. horikoshii to 2.7 Å resolution and characterized its substrate specificity. The enzyme is relatively promiscuous and reduces a range of disulfide, persulfide, and polysulfide compounds. These results indicate that the likely in vivo substrates are NAD(P)H and di-, poly-, and persulfide derivatives of coenzyme A, although polysulfide itself is also efficiently reduced. The role of the enzyme in the reduction of elemental sulfur (S(8)) in situ is not, however, ruled out by these results, and the possible roles of this substrate are discussed. During aerobic persulfide reduction, rapid recycling of the persulfide substrate was observed, which is proposed to occur via sulfide oxidation by O(2) and/or H(2)O(2). As expected, this reaction disappears under anaerobic conditions and may explain observations by others that CoADR is not essential for S(0) respiration in Pyrococcus or Thermococcus but appears to participate in oxidative defense in the presence of S(0). When compared to the homologous Npsr enzyme from Shewanella loihica PV-4 and homologous enzymes known to reduce CoA disulfide, the phCoADR structure shows a relatively restricted substrate channel leading into the sulfur-reducing side of the FAD isoalloxazine ring, suggesting how this enzyme class may select for specific disulfide substrates.

  View details for DOI 10.1021/bi3014399

  View details for Web of Science ID 000318143700006

  View details for PubMedID 23530771

• Purification of high yields of catalytically active lysyl oxidase directly from Escherichia coli cell culture PROTEIN EXPRESSION AND PURIFICATION Herwald, S. E., Greenaway, F. T., Lopez, K. M. 2010; 74 (1): 116–21

  Abstract

  Lysyl oxidase is a highly insoluble enzyme requiring high concentrations of urea to solubilize. A method to obtain lysyl oxidase in high yields directly from an Escherichia coli culture without the need for refolding of inclusion bodies has been developed using nutrient rich media. pET21b was used to overexpress the lysyl oxidase enzyme and to introduce a C-terminal 6X histidine tag for purification. Lysyl oxidase yields of 10 mg of active and properly folded enzyme per liter of media have been obtained. Purification was achieved via affinity chromatography using a Ni-NTA column. Copper content was found to be 19%. LTQ cofactor formation in LOX is a self-processing event in the presence of copper. LTQ content was determined to be 24% based on reaction with phenylhydrazine to form a phenylhydrazone adduct. Quantification of this adduct was attained using the previously reported extinction coefficient of 15.4 mM(-1)cm(-1). LTQ presence was also verified by redox cycling. Specific enzymatic activity was measured to be 0.31 U/mg, one of the highest activities reported.

  View details for DOI 10.1016/j.pep.2010.06.013

  View details for Web of Science ID 000281495100015

  View details for PubMedID 20600936