All Publications

  • Transcranial ultrasound neuromodulation of the thalamic visual pathway in a large animal model and the dose‐response relationship with MR‐ARFI Scientific Reports Mohammadjavadi, M., Ash, R. T., Li, N., Gaur, P., Kubanek, J., Saenz, Y., Glover, G. H., Popelka, G. R., Norcia, A. M., Butts Pauly, K. 2022; 12: 19588
  • Histologic safety of transcranial focused ultrasound neuromodulation and magnetic resonance acoustic radiation force imaging in rhesus macaques and sheep. Brain stimulation Gaur, P., Casey, K. M., Kubanek, J., Li, N., Mohammadjavadi, M., Saenz, Y., Glover, G. H., Bouley, D. M., Pauly, K. B. 2020; 13 (3): 804–14


    BACKGROUND: Neuromodulation by transcranial focused ultrasound (FUS) offers the potential to non-invasively treat specific brain regions, with treatment location verified by magnetic resonance acoustic radiation force imaging (MR-ARFI).OBJECTIVE: To investigate the safety of these methods prior to widespread clinical use, we report histologic findings in two large animal models following FUS neuromodulation and MR-ARFI.METHODS: Two rhesus macaques and thirteen Dorset sheep were studied. FUS neuromodulation was targeted to the primary visual cortex in rhesus macaques and to subcortical locations, verified by MR-ARFI, in eleven sheep. Both rhesus macaques and five sheep received a single FUS session, whereas six sheep received repeated sessions three to six days apart. The remaining two control sheep did not receive ultrasound but otherwise underwent the same anesthetic and MRI procedures as the eleven experimental sheep. Hematoxylin and eosin-stained sections of brain tissue (harvested zero to eleven days following FUS) were evaluated for tissue damage at FUS and control locations as well as tissue within the path of the FUS beam. TUNEL staining was used to evaluate for the presence of apoptosis in sheep receiving high dose FUS.RESULTS: No FUS-related pre-mortem histologic findings were observed in the rhesus macaques or in any of the examined sheep. Extravascular red blood cells (RBCs) were present within the meninges of all sheep, regardless of treatment group. Similarly, small aggregates of perivascular RBCs were rarely noted in non-target regions of neural parenchyma of FUS-treated (8/11) and untreated (2/2) sheep. However, no concurrent histologic abnormalities were observed, consistent with RBC extravasation occurring as post-mortem artifact following brain extraction. Sheep within the high dose FUS group were TUNEL-negative at the targeted site of FUS.CONCLUSIONS: The absence of FUS-related histologic findings suggests that the neuromodulation and MR-ARFI protocols evaluated do not cause tissue damage.

    View details for DOI 10.1016/j.brs.2020.02.017

    View details for PubMedID 32289711

  • Multimodality Hyperpolarized C-13 MRS/PET/Multiparametric MR Imaging for Detection and Image-Guided Biopsy of Prostate Cancer: First Experience in a Canine Prostate Cancer Model MOLECULAR IMAGING AND BIOLOGY Bachawal, S. V., Park, J., Valluru, K. S., Loft, M., Felt, S. A., Vilches-Moure, J. G., Saenz, Y. F., Daniel, B., Iagaru, A., Sonn, G., Cheng, Z., Spielman, D. M., Willmann, J. K. 2019; 21 (5): 861–70
  • Tails of an Indian Safari Saenz, Y. Blurb. 2019; 1
  • An intravascular magnetic wire for the high-throughput retrieval of circulating tumour cells in vivo NATURE BIOMEDICAL ENGINEERING Vermesh, O., Aalipour, A., Ge, T., Saenz, Y., Guo, Y., Alam, I. S., Park, S., Adelson, C. N., Mitsutake, Y., Vilches-Moure, J., Godoy, E., Bachmann, M. H., Ooi, C., Lyons, J. K., Mueller, K., Arami, H., Green, A., Solomon, E., Wang, S. X., Gambhir, S. S. 2018; 2 (9): 696–705
  • Anatomical Road Mapping Using CT and MR Enterography for Ultrasound Molecular Imaging of Small Bowel Inflammation in Swine. European radiology Wang, H. n., Felt, S. A., Guracar, I. n., Taviani, V. n., Zhou, J. n., Sigrist, R. M., Zhang, H. n., Liau, J. n., Vilches-Moure, J. G., Tian, L. n., Saenz, Y. n., Bettinger, T. n., Hargreaves, B. A., Lutz, A. M., Willmann, J. K. 2018; 28 (5): 2068–76


    To evaluate the feasibility and time saving of fusing CT and MR enterography with ultrasound for ultrasound molecular imaging (USMI) of inflammation in an acute small bowel inflammation of swine.Nine swine with ileitis were scanned with either CT (n = 3) or MR (n = 6) enterography. Imaging times to load CT/MR images onto a clinical ultrasound machine, fuse them to ultrasound with an anatomical landmark-based approach, and identify ileitis were compared to the imaging times without anatomical road mapping. Inflammation was then assessed by USMI using dual selectin-targeted (MBSelectin) and control (MBControl) contrast agents in diseased and healthy control bowel segments, followed by ex vivo histology.Cross-sectional image fusion with ultrasound was feasible with an alignment error of 13.9 ± 9.7 mm. Anatomical road mapping significantly reduced (P < 0.001) scanning times by 40%. Localising ileitis was achieved within 1.0 min. Subsequently performed USMI demonstrated significantly (P < 0.001) higher imaging signal using MBSelectin compared to MBControl and histology confirmed a significantly higher inflammation score (P = 0.006) and P- and E-selectin expression (P ≤ 0.02) in inflamed vs. healthy bowel.Fusion of CT and MR enterography data sets with ultrasound in real time is feasible and allows rapid anatomical localisation of ileitis for subsequent quantification of inflammation using USMI.• Real-time fusion of CT/MRI with ultrasound to localise ileitis is feasible. • Anatomical road mapping using CT/MRI significantly decreases the scanning time for USMI. • USMI allows quantification of inflammation in swine, verified with ex vivo histology.

    View details for PubMedID 29170798

  • Reduction of Muscle Contractions during Irreversible Electroporation Therapy Using High Frequency Bursts of Alternating Polarity Pulses: A Laboratory Investigation in an Ex Vivo Swine Model Journal of Vascular and Interventional Radiology Sano, M. B., Fan, R. E., Chenga, K., Saenz, Y., Sonn, G. A., Hwang, G. L., Xinga, L. 2018
  • Natural Wonders of East Africa Saenz, Y. Blurb. 2018; 1
  • Dynamic Measurement of Arterial Liver Perfusion With an Interventional C-Arm System. Investigative radiology Datta, S., Müller, K., Moore, T., Molvin, L., Gehrisch, S., Rosenberg, J., Saenz, Y., Manhart, M., Deuerling-Zheng, Y., Kothary, N., Fahrig, R. 2017


    Objective intraprocedural measurement of hepatic blood flow could provide a quantitative treatment end point for locoregional liver procedures. This study aims to validate the accuracy and reproducibility of cone-beam computed tomography perfusion (CBCTp) measurements of arterial liver perfusion (ALP) against clinically available computed tomography perfusion (CTp) measurements in a swine embolization model.Triplicate CBCTp measurements using a selective arterial contrast injection were performed before and after complete embolization of the left lobe of the liver in 5 swine. Two CBCTp protocols were evaluated that differed in sweep duration (3.3 vs 4.5 seconds) and the number of acquired projection images (166 vs 248). The mean ALP was measured within identical volumes of interest selected in the embolized and nonembolized regions of the perfusion map generated from each scan. Postembolization CBCTp values were also compared with CTp measurements.The 2 CBCTp protocols demonstrated high concordance correlation (0.90, P < 0.001). Both CBCTp protocols showed higher reproducibility than CTp in the nontarget lobe, with an intraclass correlation of 0.90 or greater for CBCTp and 0.83 for CTp (P < 0.001 for all correlations). The ALP in the embolized lobe was nearly zero and hence excluded for reproducibility. High concordance correlation was observed between the CTp and each CBCTp protocol, with the shorter CBCTp protocol reaching a concordance correlation of 0.75 and the longer achieving 0.87 (P < 0.001 for both correlations).Dynamic blood flow measurement using an angiographic C-arm system is feasible and produces quantitative results comparable to CTp.

    View details for DOI 10.1097/RLI.0000000000000368

    View details for PubMedID 28306699

  • Nature Photography in the Land of the Incas Sáenz, Y. Blurb. 2017
  • Anatomical Road Mapping Using CT and MR Enterography for Ultrasound Molecular Imaging of Small Bowel Inflammation in Swine European Radiology Wang, H., Felt, S., Guaracar, I., Taviani, V., Zhou, J., Sigrist, R., Zhang, H., Liau, J., Vilches-Moure, J., Tian, L., Sáenz, Y., Bettinger, T., Hargreaves, B., Lutz, A., Willmann, J. 2017: 1-9
  • Ecuador’s Magical Birding Circuit. Sáenz , Y. Blurb. 2016; 1
  • Jewels of the Pantanal and the Brazilian Atlantic Forest. Sáenz, Y. Blurb. 2016
  • Wild Faces of Southern Africa. Sáenz, Y. Blurb. 2016
  • The Birds of California Saenz, Y. Blurb. 2015
  • Costa Rica: Nature Photography in the Land of Pure Life. Sáenz , Y. Blurb. 2015; 1
  • Memorias de un Héroe Llamado Guardaparques Saenz, Y. Blurb. 2006
  • Endoscopic selective neck dissection in a porcine model ARCHIVES OF OTOLARYNGOLOGY-HEAD & NECK SURGERY Terris, D. J., Monfared, A., Thomas, A., Kambham, N., Saenz, Y. 2003; 129 (6): 613-617


    To investigate the feasibility of accomplishing a selective neck dissection (SND) endoscopically.Prospective, nonrandomized experimental investigation in a porcine model.Unilateral endoscopic SNDs were performed in Yorkshire pigs. A spacious operative pocket was developed using a combination of hernia balloon expansion followed by low-pressure (4 mm Hg) carbon dioxide insufflation. The sternomastoid muscle, thymus, submandibular gland, lymph nodes, and fibrofatty tissue were removed in a procedure approximating a human SND. Data (operative time, blood loss, arterial blood gas values, weight of the specimen, and complications) were prospectively recorded. The specimens were analyzed by a pathologist, and the number and size of lymph nodes were recorded.Fourteen endoscopic SNDs were successfully performed. No conversions to open surgery were necessary. The median operative time was 131 minutes (range, 95-235 minutes). The median estimated blood loss was 4 mL (range, 0-150 mL). The mean +/- SD specimen weight was 42.9 +/- 8.3 g; the mean number +/- SD of nodes retrieved from the neck specimen was 4.8 +/- 2.2, and the mean +/- SD maximal nodal dimension was 2.4 +/- 0.5 cm. The arterial PCO2 increased by an average of only 3.9 mm Hg from the beginning to the end of the surgery; correspondingly, the pH fell by only 0.02. There were no major complications, and no animals had to be euthanized prior to the completion of the procedure.Endoscopic neck dissection in a porcine model can be accomplished with a combination of strategies to overcome the dilemma of creating and maintaining an operative pocket. The merger of SND with endoscopic technology offers the promise of truly minimally invasive surgery for the node-negative neck.

    View details for Web of Science ID 000183409600003

    View details for PubMedID 12810462

  • A porcine model for endolaparoscopic abdominal aortic repair and endoscopic training. JSLS : Journal of the Society of Laparoendoscopic Surgeons / Society of Laparoendoscopic Surgeons Martinez, B. D., Zarins, C. K., Daunt, D. A., Coleman, L. A., Saenz, Y., Fogarty, T. J., Hermann, G. D., Nezhat, C. R., Olsen, E. K. 2003; 7 (2): 129-136


    The goals of this laboratory model were to evaluate the performance of the surgical team and endolaparoscopic techniques in the porcine model of infrarenal abdominal aortic repair.Twenty-four pigs underwent full endolaparoscopic aorto-aortic graft implantation with voice-activated computerized robotics. The first group of 10 pigs (acute) was sacrificed while under anesthesia at 0.5 hours (5 animals) and 2 hours (5 animals). The second group of 14 pigs (survival) were recovered from anesthesia and maintained for 7 hours (5 pigs) and 7 days (9 pigs) prior to sacrifice. Survival animals were observed for evidence of hind limb dysfunction. All grafts were visually inspected at autopsy.All animals survived the operation. All grafts were successfully implanted, and all were patent with intact anastomoses at autopsy. Mean aortic clamp time for each group was as follows: acute, 92.9 +/- 28.04 minutes; survival, 59.6 +/- 13.8 minutes; P=0.0008. Total operative time for each group was as follows: acute, 179 +/- 39.6 minutes; survival, 164.6 +/- 48 minutes; P=0.44 ns. Estimated blood loss for each group was as follows: acute, 214 -/+ 437.8 mL; survival 169.2 +/- 271 mL; P=0.76 ns. from respiratory arrest; 1 animal suffered motor sensory dysfunction of the hind limbs (spinal cord ischemia); significant bleeding occurred in 6 of 24 pigs; 8 of the 9 seven-day survivors required minimal pain medication and had normal hind limb function.The reduction in aortic clamp time, total operative time, and blood loss as the study progressed indicate the feasibility of this surgical protocol and the maturation of the learning process, which is paramount in prevention of 2 main sources of morbidity: bleeding and spinal cord ischemia. The reduction in aortic clamp time between the acute and survival groups was dramatic and statistically significant. An intensive formal training program combining dry and live surgical laboratories is deemed essential for the development of endoscopic skill sets necessary for this challenging procedure.

    View details for PubMedID 12856843

    View details for PubMedCentralID PMC3015489

  • Histology findings of disc, end plate and neural elements after coblation of nucleus pulposus: an experimental study The Spine Journal 3(6) Chen, Y., Lee, S., Sáenz, Y., Lehman, N. 2003; 3 (6): 466–470.
  • Mucus secretion from single submucosal glands of pig - Stimulation by carbachol and vasoactive intestinal peptide JOURNAL OF BIOLOGICAL CHEMISTRY Joo, N. S., Saenz, Y., Krouse, M. E., Wine, J. J. 2002; 277 (31): 28167-28175


    Secretion rates of >700 individual glands in isolated tracheal mucosa from 56 adult pigs were monitored optically. "Basal" secretion of 0.7 +/- 0.1 nl x min(-1) gland(-1) was observed 1-9 h post-harvest but was near zero on day 2. Secretion to carbachol (10 microm) peaked at 2-3 min and then declined to a sustained phase. Peak secretion was 12.4 +/- 1.1 nl x min(-1) gland(-1); sustained secretion was approximately one-third of peak secretion. Thapsigargin (1 microm) increased secretion from 0.1 +/- 0.05 to 0.7 +/- 0.2 nl x min(-1) gland(-1); thapsigargin did not cause contraction of the trachealis muscles. Isoproterenol and phenylephrine (10 microm each) were ineffective, but vasoactive intestinal peptide (1 microm) and forskolin (10 microm) each produced sustained secretion of 1.0 +/- 0.5 and 1.7 +/- 0.2 nl x min(-1) gland(-1), respectively. The density of actively secreting glands was 1.3/mm(2). Secretion to either carbachol or forskolin was inhibited (approximately 50%) by either bumetanide or HCO(3)(-) removal and inhibited approximately 90% by the combined treatments. Mucus secreted in response to carbachol or forskolin was acidic by approximately 0.2 pH units relative to the bath and remained acidic by approximately 0.1 pH units after bumetanide. The strong secretory response to vasoactive intestinal peptide, the acidity of [cAMP](i)-stimulated mucus, and its inhibition by bumetanide were unexpected.

    View details for DOI 10.1074/jbc.M202712200

    View details for Web of Science ID 000177189800074

    View details for PubMedID 12011087

  • Endoscopic resection of the submandibular gland in a porcine model LARYNGOSCOPE Monfared, A., Saenz, Y., Terris, D. J. 2002; 112 (6): 1089-1093


    To examine the feasibility of endoscopic resection of the submandibular gland in a porcine model.Experimental, nonrandomized prospective study.Twelve endoscopic submandibular gland resections were performed on seven Yorkshire adult pigs using a combination of balloon dissection and low-pressure CO2 insufflation. The operative time, blood loss, blood pressure, oxygen saturation, temperature, arterial blood gas values, and weight of the glands were measured.All 12 submandibular gland resections were successfully performed endoscopically, and no conversions to open resection were necessary. The procedures lasted 42 to 140 minutes (median duration, 59 min). The median estimated blood loss was 15 mL. The submandibular glands weighed 13.3 +/- 1.5 g. The arterial blood pH varied from a decrease of 0.08 to an increase of 0.09 units from the beginning to the end of the operation. Similarly, the arterial CO2 pressure at the end of the case varied from a decrease of 15.8 to an increase of 16.2 mm Hg from the starting value. The presence of normal glandular architecture and lack of trauma or thermal injury were confirmed histologically. There were no cases of pneumothorax or air embolism, and no animals had to be killed. In one animal, a modest amount of subcutaneous emphysema could be appreciated, which was confined to the area over the operative pocket.Endoscopic resection of the submandibular gland is possible by combining balloon dissection with low-pressure CO2 insufflation, thereby avoiding complications of high-pressure insufflation such as pneumothorax and air embolism.

    View details for Web of Science ID 000176931500028

    View details for PubMedID 12160279

  • Endoscopic and robotic surgery in the neck: Experimental and clinical applications Operative Techniques in Otolaryngology—Head and Neck Surgery Terris, D. J., Hauss, B., Lee, D., Sáenz , Y. 2002; 13 (3): 231-238
  • Comparison of the da Vinci robotic surgical system to standard laparoscopic technique in porcine pyeloplasty: an examination of anastomotic efficiency. Journal of Urology Kaynan, A. M., Sáenz, Y., Gill, H., Winfield, H. N. 2002; 167 (4)
  • Optical method for quantifying rates of mucus secretion from single submucosal glands AMERICAN JOURNAL OF PHYSIOLOGY-LUNG CELLULAR AND MOLECULAR PHYSIOLOGY Joo, N. S., Wu, J. V., Krouse, M. E., Saenz, Y., Wine, J. J. 2001; 281 (2): L458-L468


    We describe an optical method to quantify single- gland secretion. Isolated tracheal mucosa were mounted at the air-Krebs interface and coated with oil. Gland secretions formed spherical bubbles that were digitally imaged at intervals, allowing rates of secretion to be calculated. We monitored 340 glands in 54 experiments with 12 sheep. Glands secreted basally at low rates (0.57 +/- 0.04 nl x min(-1) x gland(-1), 123 glands) in tissues up to 9 h postharvest and at lower rates for up to 3 days. Carbachol (10 microM) stimulated secretion with an early transient and a sustained or oscillating phase. Peak secretion was 15.7 +/- 1.2 nl x min(-1) x gland(-1) (60 glands); sustained secretion was 4.5 +/- 0.5 nl x min(-1) x gland(-1) (10 glands). Isoproterenol and phenylephrine (10 microM each) stimulated only small, transient responses. We confirmed that cats have a large secretory response to phenylephrine (11.6 +/- 3.7 nl x min(-1) x gland(-1), 12 glands), but pigs, sheep, and humans all have small responses (<2 nl x min(-1)m x gland(-1)). Carbachol-stimulated peak secretion was inhibited 56% by bumetanide, 67% by HCO replacement with HEPES, and 92% by both. The distribution of secretion rates was nonnormal, suggesting the existence of subpopulations of glands.

    View details for Web of Science ID 000169637600021

    View details for PubMedID 11435221

  • HCO3- transport in relation to mucus secretion from submucosal glands. JOP : Journal of the pancreas Joo, N. S., Krouse, M. E., Wu, J. V., Saenz, Y., Jayaraman, S., Verkman, A. S., Wine, J. J. 2001; 2 (4): 280-284


    The role of HCO(3)(-) transport in relation to fluid secretion by submucosal glands is being studied in sheep, pigs, cats and humans. Optical methods have been developed to measure secretion rates of mucus volume from single glands with sufficient temporal resolution to detect differences in minute-by-minute secretion rates among glands. The ionic composition and viscoelastic properties of the uncontaminated gland mucus are measured with a combination of ratiometric fluorescent indicators, ion-selective microelectrodes, FRAP, and a miniaturized, magnetic force viscometer. Sheep glands secreted basally at low rates, showed small, transient responses to alpha- and beta-adrenergic agonists, and large responses to a cholinergic agonist, carbachol. Peak rates and temporal patterns of responses to carbachol differed markedly among glands. To assess the contribution of HCO(3)(-) transport to gland secretion, we either inhibited Na(+)/K(+)/2Cl(-) cotransporter (NKCC) with bumetanide or replaced HCO(3)(-) with HEPES and gassed with O(2). Bumetanide caused a small, non-significant inhibition of basal secretion, but removal of HCO(3)(-)/CO(2) significantly reduced basal secretion almost by half. Both bumetanide and removal of HCO(3)(-)/CO(2) reduced carbachol-stimulated secretion significantly, with HCO(3)(-) removal having the larger effect: a reduction to 33% of control (P<0.01). The remaining secretory response to carbachol was nearly eliminated by bumetanide. Sheep mucus pH measured with ion selective electrodes was about 0.4 log more acidic than the bath. In humans, we observed the same pattern of responses to agonists and antagonists as in sheep, and observed a mucus pH of 7.0 using 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF). We hypothesize that HCO(3)(-) transport is important in the formation of mucus secretion, but that most HCO(3)(-) is scavenged before the final mucus appears at the duct opening. Cystic fibrosis transmembrane conductance regulator's (CFTR) best understood function is as an anion channel, but increasing attention has been given to its role in HCO(3)(-) transport. By analogy with organ-specific CFTR effects on Cl(-) transport, it seems likely that the relative importance of CFTR in HCO(3)(-) transport will also vary across organs. Because lung disease is by far the greatest cause of mortality among people with cystic fibrosis, it is important to determine how loss of CFTR function causes lung disease. We are testing the hypothesis that loss of CFTR alters serous cell secretion in the lungs, and the corollary that such loss contributes to cystic fibrosis (CF) lung disease. CFTR is highly expressed in serous cells of submucosal glands and the Calu-3 serous cell model secretes HCO(3)(-). Human gland serous cells grown in culture and tested for fluid secretion under open circuit conditions showed reduced fluid secretion to all mediators. However, submucosal glands are complex organs containing at least 4 distinct regions and at least that many cell types, making it difficult to predict the consequences on whole-organ function from experiments with individual cell types. Therefore, we have resurrected long-neglected methods for studying whole-gland function, and have attempted to improve them in a variety of ways. We are refining these methods and increasing our understanding of gland function by studying tracheal glands from sheep, pigs and cats. As human tissues become available, they are studied with the best methods presently available. The key questions now being asked are: Is mucus secretion from submucosal glands altered in cystic fibrosis? If so, how is it altered and how does it contribute to CF lung disease? Answering the last question will require an understanding of how glands interact with other regions of the lung. In the context of this meeting, we present preliminary data on the role of HCO(3)(-) in gland mucus secretion.

    View details for PubMedID 11875272

  • Pharmacology of mucus secretion by single submucosal glands of the pig. Pediatric Pulmonology Joo, N. S., Krouse, M., Wu, J., Sáenz, Y., Wine, J. J. 2001; 22 (145): 1
  • Anesthetic management for laparoscopic aortic surgery in a porcine model. Contemporary Topics by the American Association for Laboratory Animal Science Daunt, D., Martinez, B., Zarins, C., Sáenz, Y., Coleman, L., Young, L., Nelson, G., Bagley, L., DeiRossi , M., Bruce, M. 2000; 39 (4)
  • Mucus secretion from individual tracheal submucosal glands from sheep. Pediatric Pulmonology Joo, N. S., Sáenz, Y., Krouse, M., Wu, J., Wine, J. J. 2000: 121