Papers by Michael Talcott
Circulation, Nov 26, 2013
The Journal of Urology, Apr 1, 2005
INTRODUCTION AND OBJECTIVE: Laparoscopic nephron-sparing surgery (LNSS) is frequently reserved fo... more INTRODUCTION AND OBJECTIVE: Laparoscopic nephron-sparing surgery (LNSS) is frequently reserved for smaller peripherally located tumors. Centrally located tumors typically require complex intra-corporeal suturing and reconstruction which is often difficult within the constraints of minimizing warm or cold ischemia. Our objective was to compare our experience with central and peripheral tumors treated with LNSS. METHODS: We identified 154 and 209 patients with central and peripheral tumors treated with LNSS, respectively. Central tumors were defined as tumors touching, abutting, or directly invading the collecting system and/or hilar vasculature. Lesions with no contact with the hilar structures were classified as peripheral. Preoperative and pathologic characteristics as well as intraoperative, early postoperative (while hospitalized), and late postoperative (following dismissal) complications were compared between the groups using chi-square and Wilcox rank sum tests. RESULTS: A retroperitoneal approach was used in 29.9% of central and 31.9% of peripheral lesions. All patients in the central group required a collecting system repair. Central tumors were larger on preoperative imaging (median 3.0 vs. 2.4 em, p<O.OOl) and had larger specimens at surgery (median 43 vs. 22 gm, p<O.OOl) than peripheral tumors. Central tumors required slightly longer operative times (210 vs. 180 minutes, p=0.008) warm ischemia times (33.5 vs. 30.0 minutes, p<O.OOI), and hospital stays (67 vs. 60 hours, p<O.OOI), although these differences were not clinically significant. The incidence of margin positivity was 0.8% vs. 1.7% (p=0.502) for the central and peripheral groups. The median estimated blood loss was the same in both groups at ISO cc. The median postoperative creatinine was 1.2 and 1.1 mg/dL for central and peripheral lesions, respectively. There were more intraoperative and early postoperative complications in the central group compared with the peripheral group (I 0.4% vs. 6.2% and 22.6% vs. 16.1%, respectively), although these differences were not statistically significant. The incidence of late complications in the two groups was approximately 13.0%. The most common early and late postoperative complication in the central group was hemorrhage at 3%. CONCLUSIONS: LNSS for centrally located tumors is a technically challenging procedure. However, it can be performed safely with complication rates that are comparable to those achieved with peripheral tumors. Indications for LNSS should be expanded to include centrally located tumors.
The Journal of Urology, Sep 1, 2021
American Journal of Physiology-heart and Circulatory Physiology, May 1, 1994
Eight chronically instrumented conscious dogs were used to test the hypothesis that left ventricu... more Eight chronically instrumented conscious dogs were used to test the hypothesis that left ventricular (LV) relaxation is accelerated during cardiac tamponade. The time constant of LV transmural pressure fall was measured before and during intrapericardial (IP) saline infusion (baseline) with and without beta-adrenergic blockade (propranolol 1 mg/kg iv). Heart rate was controlled by atrial pacing. Increasing IP pressure caused a progressive linear decrease in stroke volume before and during beta-blockade in each animal. The time constant of LV transmural pressure fall also decreased continuously with an increase in IP pressure from 26 +/- 7 ms during baseline to 18 +/- 5 ms during severe cardiac tamponade (P &lt; 0.01) before beta-blockade. However, after beta-blockade, the time constant of LV transmural pressure fall was constant over a wide range of IP pressures despite a continuous decrease in LV end-diastolic volume. The time constant of LV transmural pressure fall was not altered by vena caval occlusions that caused the same decrease in LV preload observed during cardiac tamponade. We concluded that despite decreased pump function, LV relaxation was accelerated progressively during graded cardiac tamponade, and this change was dependent not on changes in loading conditions but on an intact beta-adrenergic influence.
ABSTRACTMechanical ventilators are essential to patients who become critically ill from acute res... more ABSTRACTMechanical ventilators are essential to patients who become critically ill from acute respiratory distress syndrome (ARDS), and shortages have been reported due to the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We utilized cost-effective, on-demand 3D printing (3DP) technology to produce critical components for a novel ventilator multiplexer system, Vent-Lock, to split one ventilator or anesthesia gas machine between two patients. FloRest, a novel 3DP flow restrictor, provides clinicians control of tidal volumes and positive end expiratory pressure (PEEP), using the 3DP manometer adaptor to monitor pressures. We tested the ventilator splitter circuit in simulation centers between artificial lungs and used an anesthesia gas machine to successfully ventilate two swines. As one of the first studies to demonstrate splitting one anesthesia gas machine between two swines, we present proof-of-concept of a de novo, closed, multiplexing system, with flow rest...
Fluids and Barriers of the CNS, 2022
Background Hydrocephalus is a neurological disease with an incidence of 80–125 per 100,000 births... more Background Hydrocephalus is a neurological disease with an incidence of 80–125 per 100,000 births in the United States. Neuropathology comprises ventriculomegaly, periventricular white matter (PVWM) alterations, inflammation, and gliosis. We hypothesized that hydrocephalus in a pig model is associated with subventricular and PVWM cellular alterations and neuroinflammation that could mimic the neuropathology described in hydrocephalic infants. Methods Hydrocephalus was induced by intracisternal kaolin injections in 35-day old female pigs (n = 7 for tissue analysis, n = 10 for CSF analysis). Age-matched sham controls received saline injections (n = 6). After 19–40 days, MRI scanning was performed to measure the ventricular volume. Stem cell proliferation was studied in the Subventricular Zone (SVZ), and cell death and oligodendrocytes were examined in the PVWM. The neuroinflammatory reaction was studied by quantifying astrocytes and microglial cells in the PVWM, and inflammatory cytok...
Mechanical ventilators are essential to patients who become critically ill from acute respiratory... more Mechanical ventilators are essential to patients who become critically ill from acute respiratory distress syndrome (ARDS), and shortages have been reported due to the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We utilized cost-effective, on-demand 3D printing (3DP) technology to produce critical components for a novel ventilator multiplexer system, Vent-Lock, to split one ventilator or anesthesia gas machine between two patients. FloRest, a novel 3DP flow restrictor, provides clinicians control of tidal volumes and positive end expiratory pressure (PEEP), using the 3DP manometer adaptor to monitor pressures. We tested the ventilator splitter circuit in simulation centers between artificial lungs and used an anesthesia gas machine to successfully ventilate two swines. As one of the first studies to demonstrate splitting one anesthesia gas machine between two swines, we present proof-of-concept of a de novo, closed, multiplexing system, with flow restriction ...
Laboratory Animal Medicine, 2015
Since the publication of the second edition of this text in 2004, the primacy of genetically engi... more Since the publication of the second edition of this text in 2004, the primacy of genetically engineered animals has been firmly established. The creation of transgenic and knockout mice with a wide variety of genotypes has revolutionized the study of many disease entities, some of which could previously be modeled only in larger animal species. The complete sequencing of a number of pertinent genomes, including the mouse, guinea pig, rabbit, and dog, along with the associated emerging fields of transcriptomics, proteomics, and metabolomics, has led to an increasingly insightful and focused inquiry into the nature of life and disease. A foundation for these inquiries is the enduring need to define and manipulate the animal model, and the comparative medicine scientist or clinician is the agent who develops and implements the techniques and procedures that are the essential tools for discovery.
Surgical Endoscopy, 2007
Aim To compare the safety and efficacy of four energybased vascular sealing and cutting instrumen... more Aim To compare the safety and efficacy of four energybased vascular sealing and cutting instruments. Methods Blood vessels of various types and diameters were harvested from four pigs using four instruments: Harmonic ACE TM (Ethicon Endo-Surgery, Cincinnati, OH), LigaSure TM V and LigaSure Atlas TM (Valleylab, Inc., Boulder, CO; a division of Tyco Healthcare), and En-Seal TM vessel fusion system (SurgRx, Inc. Redwood City, CA). The diameters of the vessels, speed and adequacy of the cutting and sealing process, and bursting pressures were compared. An additional set of specimens was sealed and left in situ for up to 4 h after which the vessels were harvested and histopathologically analyzed for the degree of thermal injury. Results The bursting pressures were significantly higher with EnSeal TM compared to all other instruments (p \ 0.0001). The sealing process was significantly shorter with Harmonic ACE TM and significantly longer with LigaSure Atlas TM (p \0.0001). The mean seal width was larger with the LigaSure Atlas TM compared to the other instruments, and it was smaller with EnSeal TM and Harmonic ACE TM. Less radial adventitial collagen denaturation was present with EnSeal TM and LigaSure TM V than with the other two instruments; there were no significant differences in collagen denaturation although proximal thermal injury to the smooth muscle in the media of the vessel wall was less common with LigaSure Atlas TM than with the other instruments; however, the numbers were too small for statistical analysis. Conclusions The bursting pressures with EnSeal TM were significantly higher than with all the other instruments. Harmonic ACE TM was the fastest sealing instrument and LigaSure Atlas TM was slowest. EnSeal TM created less radial thermal damage to the adventitial collagen of the vessels and LigaSure Atlas TM created less thermal damage to the media of the vessels. The clinical significance of these findings is unknown. Keywords Vascular sealing Á Energy-based Á Bursting pressure Á Thermal injury Á Porcine model Recent advances in surgical technology include the use of various energy sources for sealing, coagulating, and cutting blood vessels as opposed to performing these procedures mechanically by tying, suturing, and even clipping or stapling them. The use of energy-based instruments has become even more popular in laparoscopic surgery because the traditional techniques of surgical hemostasis (pressure, tying, suturing) are not as easily laparoscopically applied. The efficacy and reliability of various energy-based vascular sealing instruments have been reported to be equivalent to the results with metallic clips and silk ties [1-3]; however, other researchers have demonstrated that energy-based devices produced either inferior [4] or
Journal of Investigative Surgery, 2009
The Guidelines have been approved by the Institutional Animal Use and Care Committee (IACUC) and ... more The Guidelines have been approved by the Institutional Animal Use and Care Committee (IACUC) and apply to all survival surgical procedures performed on rodents at CMU. These guidelines provide information on aseptic surgical techniques in rodents. They are designed for experienced investigators and technicians, and serve as a teaching tool for individuals new to experimental surgery. Prior to performing ANY surgery techniques on rodents an approved protocol must be in place with appropriately trained personal and procedures. Survival surgery on rodents should be performed using aseptic technique (sterile instruments, surgical gloves, masks, lab coats, scrubs or sterile gown,) to reduce microbial contamination. Minor surgical procedures, such as wound suturing and peripheral vessel cannulation, should be performed in accordance with standard veterinary practices. As with all new techniques, patience and practice are required to harvest full benefits from the use of aseptic surgical techniques in rodents. There is a common notion that rats are resistant to postoperative wound infection "This is False!" Relatively low-level bacterial contamination of surgical wounds may alter a rat's physiology and behavior and confound the experimental measures, even though no clinical sepsis is evident.
The Journal of Urology, 2021
The Journal of the Acoustical Society of America
Computers in Biology and Medicine
Clinically, uterine contractions are monitored with tocodynamometers or intrauterine pressure cat... more Clinically, uterine contractions are monitored with tocodynamometers or intrauterine pressure catheters. In the research setting, electromyography (EMG), which detects electrical activity of the uterus from a few electrodes on the abdomen, is feasible, can provide more accurate data than these other methods, and may be useful for predicting preterm birth. However, EMG lacks sufficient spatial resolution and coverage to reveal where uterine contractions originate, how they propagate, and whether preterm contractions differ between women who do and do not progress to preterm delivery. To address those limitations, electromyometrial imaging (EMMI) was recently developed and validated to non-invasively assess three-dimensional (3D) electrical activation patterns on the entire uterine surface in pregnant sheep. EMMI uses magnetic resonance imaging to obtain subject-specific body-uterus geometry and collects uterine EMG data from up to 256 electrodes on the body surface. EMMI software then solves an ill-posed inverse computation to combine the two datasets and generate maps of electrical activity on the entire 3D uterine surface. Here, we assessed the feasibility to clinically translate EMMI by evaluating EMMI's accuracy under the unavoidable geometrical alterations and electrical noise contamination in a clinical environment. We developed a hybrid experimental-simulation platform to model the effects of fetal kicks, contractions, fetal/maternal movements, and noise contamination caused by maternal respiration and environmental electrical activity. Our data indicate that EMMI can accurately image uterine electrical activity in the presence of geometrical deformations and electrical noise, suggesting that EMMI can be reliably translated to non-invasively image 3D uterine electrical activation in pregnant women.
Background.Many animal models have been used to study the pathophysiology of hydrocephalus; most ... more Background.Many animal models have been used to study the pathophysiology of hydrocephalus; most of these have been rodent models whose lissencephalic cerebral cortex may not respond to ventriculomegaly in ways similar to gyrencephalic species and whose size is not amenable to evaluation of clinically-relevant neurosurgical treatments. Fewer models of hydrocephalus in gyrencephalic species have been used; thus, we have expanded upon a porcine model of hydrocephalus in juvenile pigs. Methods. Acquired hydrocephalus was induced in 30-35-day old pigs by percutaneous intracisternal injections of kaolin. Intracisternal and intraventricular injections of autologous blood was attempted in 2 cases to induce post-hemorrhagic hydrocephalus. Magnetic resonance imaging (MRI) was employed to evaluate the progression of ventriculomegaly and plan the surgical implantation of ventriculoperitoneal shunts at approximately 1–4 weeks post-kaolin. Behavioral and neurological status was assessed continuo...
Science
To examine the contributions of impaired gut microbial community development to childhood undernu... more To examine the contributions of impaired gut microbial community development to childhood undernutrition, we combined metabolomic and proteomic analyses of plasma samples with metagenomic analyses of fecal samples to characterize the biological state of Bangladeshi children with severe acute malnutrition (SAM) as they transitioned, after standard treatment, to moderate acute malnutrition (MAM) with persistent microbiota immaturity. Host and microbial effects of microbiota-directed complementary food (MDCF) prototypes targeting weaning-phase bacterial taxa underrepresented in SAM and MAM microbiota were characterized in gnotobiotic mice and gnotobiotic piglets colonized with age- and growth-discriminatory bacteria. A randomized, double-blind controlled feeding study identified a lead MDCF that changes the abundances of targeted bacteria and increases plasma biomarkers and mediators of growth, bone formation, neurodevelopment, and immune function in children with MAM.
Science Translational Medicine
In current clinical practice, uterine contractions are monitored via a tocodynamometer or an intr... more In current clinical practice, uterine contractions are monitored via a tocodynamometer or an intrauterine pressure catheter, both of which provide crude information about contractions. Although electrohysterography/electromyography can measure uterine electrical activity, this method lacks spatial specificity and thus cannot accurately measure the exact location of electrical initiation and location-specific propagation patterns of uterine contractions. To comprehensively evaluate three-dimensional uterine electrical activation patterns, we describe here the development of electromyometrial imaging (EMMI) to display the three-dimensional uterine contractions at high spatial and temporal resolution. EMMI combines detailed body surface electrical recording with body-uterus geometry derived from magnetic resonance images. We used a sheep model to show that EMMI can reconstruct uterine electrical activation patterns from electrodes placed on the abdomen. These patterns closely match tho...
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Papers by Michael Talcott