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Biomedical subjects

J Collins

Publications and source records attributed to J Collins.

At least 109 records · Page 6Linked to original sources
PubMed1999

Cholinergic neurons of the pelvic autonomic ganglia and uterus of the female rat: distribution of axons and presence of muscarinic receptors.

Acetylcholine (ACh) stimulates contraction of the uterus and dilates the uterine arterial supply. Uterine cholinergic nerves arise from the paracervical ganglia and were, in the past, characterized based on acetylcholinesterase (AChE) histochemistry. However, the histochemical reaction for acetylcholinesterase provides only indirect evidence of acetylcholine location and is a nonspecific marker for cholinergic nerves. The present study: (1) reevaluated cholinergic neurons of the paracervical ganglia, (2) examined the cholinergic innervation of the uterus by using retrograde axonal tracing and antibodies against molecules specific to cholinergic neurons, choline acetyltransferase and the vesicular acetylcholine transporter, and (3) examined muscarinic receptors in the paracervical ganglia using autoradiography and a radiolabeled agonist. Most ganglionic neurons were choline acetyltransferase- and vesicular acetylcholine transporter-immunoreactive and were apposed by choline acetyltransferase/vesicular acetylcholine transporter-immunoreactive terminals. Retrograde tracing showed that some cholinergic neurons projected axons to the uterus. These nerves formed moderately dense plexuses in the myometrium, cervical smooth muscle and microarterial system of the uterine horns and cervix. Finally, the paracervical ganglia contain muscarinic receptors. These results clearly reveal the cholinergic innervation of the uterus and cervix, a source of these nerves, and demonstrate the muscarinic receptor content of the paracervical ganglia. Cholinergic nerves could play significant roles in the control of uterine myometrium and vasculature.

Acetylcholinesterase↗
PubMed1999

Calretinin-immunoreactive nerves in the uterus, pelvic autonomic ganglia, lumbosacral dorsal root ganglia and lumbosacral spinal cord.

Nerves containing the calcium-binding protein calretinin have been reported in several organs but not in female reproductive organs and associated ganglia. This study was undertaken to determine if nerves associated with the uterus contain calretinin and the source(s) of calretinin-synthesizing nerves in the rat (are they sensory, efferent, or both?). Calretinin-immunoreactive nerves were present in the uterine horns and cervix where they were associated with arteries, uterine smooth muscle, glands, and the epithelium. Calretinin-immunoreactive terminals were apposed to neurons in the paracervical ganglia; in addition, some postganglionic neurons in this ganglion were calretinin positive. Calretinin perikarya were present in the lumbosacral dorsal root ganglia, no-dose ganglia, and lumbosacral spinal cord. Retrograde axonal tracing, utilizing Fluorogold injected into the uterus or paracervical parasympathetic ganglia, revealed calretinin-positive/Fluorogold-labeled neurons in the dorsal root and nodose ganglia. Also, capsaicin treatment substantially reduced the calretinin-positive fibers in the uterus and pelvic ganglia, thus indicating the sensory nature of these fibers. The presence of calretinin immunoreactivity identifies a subset of nerves that are involved in innervation of the pelvic viscera and have origins from lumbosacral dorsal root ganglia and vagal nodose ganglia. Though the exact function of calretinin in these nerves is not currently known, calretinin is likely to play a role in calcium regulation and their function.

Animals↗
PubMed1999

Pregnancy outcome after successful external cephalic version.

OBJECTIVE: Recent studies have suggested that the rate of cesarean delivery in patients who have undergone a successful external cephalic version is higher than expected. This study compares the incidence of cesarean delivery in patients who underwent successful external cephalic version and patients with primary cephalic presentations. STUDY DESIGN: We identified and reviewed the charts of 92 patients who underwent a successful external cephalic version. We identified a control population of 184 patients from the delivery room logs. We collected outcome data and information on additional risk factors that may affect cesarean delivery rates. RESULTS: There were no significant differences between study and control populations. There was no significant difference in the cesarean delivery rate between study patients (22.8%) and control patients (23.4%). CONCLUSIONS: We could not demonstrate a significant increase in the cesarean delivery rate for women who underwent successful external cephalic version in comparison with patients in labor with primary cephalic presentations.

Adult↗
PubMed1999

Chest radiology case exchange program: a paradigm for resident teaching and independent resident learning.

RATIONALE AND OBJECTIVES: The purpose of this study was to test the effectiveness of resident-prepared, independent learning cases in teaching residents chest radiology. MATERIALS AND METHODS: Three 2nd-year residents (one each from the University of Wisconsin, the Oregon Health Sciences University, and the University of Michigan) prepared four chest radiology teaching cases each (total, 12 cases). Radiology residents from each institution were randomly divided into control (n = 30) and experimental (n = 35) groups. Residents from both groups took a pretest of 36 multiple-choice questions covering the material from the 12 teaching cases. Residents in the experimental group reviewed these cases independently, and both groups took the same test (posttest) immediately after the teaching cases had been reviewed and again 3 months later (final test). RESULTS: Test scores were similar across institutions (P > .05) but differed across time and treatment groups (experimental vs control) (P < .0001). Mean differences in test scores between the experimental and control groups at pretest, posttest, and final test were -0.4, +9.0, +4.0, respectively, demonstrating increased performance at posttesting that was still present (though somewhat attenuated) 3 months later at final testing. CONCLUSION: Independent study of resident-prepared chest radiology teaching cases increases the resident's knowledge for as long as 3 months after instruction.

Analysis of Variance↗
PubMed1999

Medical students and radiology residents: can they learn as effectively with the same educational materials?

RATIONALE AND OBJECTIVES: The purpose of this study was to evaluate the effectiveness of resident-prepared, independent-learning materials for teaching chest radiology to medical students. MATERIALS AND METHODS: Students from three U.S. medical schools enrolled in radiology clerkships between March 1998 and June 1998 were randomly divided into control (n = 27) and experimental (n = 31) groups. The experimental group studied 12 chest radiology independent-learning cases (intervention) used to teach radiology residents in a previous study. Both groups took a 36-item, multiple-choice test (previously used to test radiology residents) on three occasions (before intervention [pretest], 1 day after intervention [posttest], and 2-4 weeks after intervention [final examination]). Student scores were then compared with resident scores. RESULTS: Mean scores were similar across institutions at pretest, but increases at posttest and final examination scores differed across time, school, and group (P < .005). Mean differences in scores between experimental and control groups at pretest, posttest, and 2-4-week final examination were -0.22, 9.79, and 9.14, respectively, demonstrating increased performance at posttesting that remained present (though slightly attenuated) 2-4 weeks later. Comparing performance, residents had mean pretest scores of 19.2 and students of 14.1, a five-point difference attributable to the residents' greater experience. Both residents and students gained approximately nine points at posttest. At final examination, the difference between residents and students was only 1.4 points, suggesting the experimental program (teaching materials) brought students close to the long-term retention shown by residents. CONCLUSION: Independent study of resident-prepared chest radiology teaching cases increased medical student knowledge for at least 2 or 4 weeks after instruction. Although starting at lower knowledge levels, students experienced gains in knowledge comparable to those of residents, suggesting the same materials can be used to teach both students and residents.

Education, Medical, Undergraduate↗
PubMed1999

Effectiveness of resident-prepared conferences in teaching imaging utilization guidelines to radiology residents.

RATIONALE AND OBJECTIVES: The authors evaluated the effectiveness of a resident-prepared conference series for teaching imaging utilization guidelines to radiology residents. MATERIALS AND METHODS: Brown University radiology residents (n = 17) gave 61 presentations on imaging utilization to their colleagues during 16 1-hour conferences. The residents were later examined on the topics presented and surveyed about their familiarity with the American College of Radiology appropriateness criteria, their exposure to issues of cost-effectiveness, and their degree of confidence in providing imaging consultation. The same examination and survey were administered to control residents from the University of Wisconsin (n = 14) and the Oregon Health Sciences University (n = 14). Scores were compared by using linear regression and Wilcoxon rank sum tests. RESULTS: Controlling for years in radiology residency, residents at Brown scored on average 16.0% (standard error = 2.2%) higher than residents at the other universities (P < .001). Controlling for institution, 3rd- and 4th-year residents scored on average 7.4% (standard error = 2.1%) higher than 1st- and 2nd-year residents (P = .001). Brown residents expressed more familiarity with American College of Radiology appropriateness criteria and appeared to have more exposure to cost-effectiveness issues in conferences than residents at Wisconsin or Oregon Health Sciences University (P < .005). Residents from the three universities did not differ in their level of confidence in providing imaging consultation. CONCLUSION: Resident-prepared conferences are an effective means of teaching imaging utilization guidelines to residents, but they do not affect the residents' perception of their ability to provide imaging consultation.

Diagnostic Imaging↗
PubMed1999

Getting residents involved in research: a challenge in the era of managed care.

The changing climate of health care, with the associated increasing financial constraints, challenges faculty and residents to find time for mentoring and pursuing research. Departments and institutions can encourage residents to conduct research by assuring them that they have a supportive infrastructure. Only when the institution and faculty value research will residents do the same. More than half of academic surgeons spend less than 20% of their effort in research; how can residency programs expect residents to enthusiastically pursue research when members of the teaching faculty are themselves not writing and publishing? If the ACGME is serious about asking residents to devote their time and energy to becoming more active in research activities, we must be prepared to decrease service commitments, and we must provide clinically active mentors and visible career models.

Academic Medical Centers↗
PubMed1999

Choroid plexus epithelium (normal and neoplastic) expresses synaptophysin. A potentially useful aid in differentiating carcinoma of the choroid plexus from metastatic papillary carcinomas.

As an incidental finding in paraffin sections of brain tissue used as positive controls for synaptophysin immunostain, the cytoplasm of choroid plexus epithelium present was found to stain strongly positively for this substance. This was subsequently found to be the case in normal choroid plexuses in autopsy material from infancy to old age, as well as in epithelial cells of papillomas and carcinomas of the choroid plexus. The latter findings may prove useful in differentiating choroid plexus carcinomas from metastatic papillary carcinomas of extracerebral origin with the exception of neuroendocrine carcinomas of various sites that are usually positive for synaptophysin.

Adolescent↗
PubMed1999

Fas-FasL interaction involved in pathogenesis of ocular toxoplasmosis in mice.

Ocular toxoplasmosis is a potentially blinding intraocular inflammation. The intent of this study was to investigate the role of Fas-FasL interaction in a murine model of acquired ocular toxoplasmosis induced by intracameral inoculation of Toxoplasma gondii. Intraocular inflammation, Fas and FasL expression on lymphocytes and on ocular tissues, the occurrence of apoptosis, and the frequency of CD8(+) and CD4(+) T cells in the infected eyes were analyzed in C57BL/6 (B6) mice. Susceptibility to parasite-induced intraocular inflammation was observed in Fas-deficient (B6-lpr) and FasL-deficient (B6-gld) mice. Inoculation of 5,000 T. gondii tachyzoites induced significant intraocular inflammation associated with increase of Fas and FasL expression in the inoculated eyes of wild-type B6 mice. Flow cytometry demonstrated a significant increase of Fas and FasL expression on the splenocytes from naive mice incubated in vitro with the parasite and on the splenocytes harvested from the infected mice at day 8 after parasite inoculation. Apoptosis of inflammatory cells and cells in ocular tissues was seen, and a greater frequency of CD8(+) than CD4(+) T cells was observed in the infected eyes. The intensity of intraocular inflammation was greater in B6-lpr and B6-gld mice than in wild-type B6 mice (P < 0.05). The results suggest that Fas-FasL interaction associated with apoptosis is involved in the pathogenesis of acquired ocular toxoplasmosis in mice.

Animals↗
PubMed1999

Lung transplantation for lymphangioleiomyomatosis: role of imaging in the assessment of complications related to the underlying disease.

PURPOSE: To identify the complications and imaging findings related to lymphangioleiomyomatosis (LAM) after lung transplantation. MATERIALS AND METHODS: The authors retrospectively reviewed the clinical histories and imaging studies of 13 patients from five major medical centers who underwent unilateral (n = 8) or bilateral (n = 5) lung transplantation for LAM between 1991 and 1997. Complications related to LAM, both before and after transplantation, were recorded. RESULTS: The following LAM-related complications were found during and after transplantation: excessive pleural adhesions (n = 4), native lung pneumothorax (n = 3), chylous effusion (n = 1), chylous ascites (n = 3), complications from renal angiomyolipomas (n = 4), and recurrent LAM (n = 1). Diagnosis could be made or suggested with computed tomography (CT) in all cases. Four patients (31%) died; one patient died of complications of LAM. CONCLUSIONS: Patients who have undergone lung transplantation for LAM have increased morbidity and mortality due to complications related to their underlying disease. These LAM-related complications can be diagnosed or suggested with CT.

Adult↗
PubMed1999

Dot immunobinding assay for detection of bovine herpesvirus 4 antibodies in rabbits.

A dot immunobinding assay (DIA) was used for the detection of antibody against bovine herpesvirus 4 (BHV-4) in experimentally infected specific-pathogen-free male and female rabbits. A semipurified virus preparation was used as the antigen, and protein A/G-horseradish-peroxidase conjugate and diaminobenzidine tetrahydrochloride were used as the detection system. Results of the DIA procedure on serum samples of experimentally infected male and female rabbits were compared with those of a complement-dependent virus neutralization (VN) test. None of the tested sera (0/60 samples) from either male or female rabbits were positive by the complement-dependent VN test. Results of the DIA procedure for the same tested sera were positive in 35 of 60 samples (58%) from BHV-4 infected rabbits, indicating higher sensitivity of DIA procedure as compared with the complement-dependent VN test.

Animals↗
PubMed1999

Pulmonary mucosa-associated lymphoid tissue lymphoma: CT and pathologic findings.

OBJECTIVE: The objective of this study was to determine the CT findings in pulmonary mucosa-associated lymphoid tissue lymphoma and to correlate these CT findings with histologic specimens. CONCLUSION: In the 11 patients reviewed, the most common CT appearance of pulmonary mucosa-associated lymphoid tissue lymphoma was consolidation with air bronchograms, correlating histologically with a cellular lymphocytic infiltrate expanding the interstitium and compressing adjacent alveoli, producing air bronchograms.

Female↗
PubMed1999

Protective role of maternal antibodies against Haemophilus parasuis infection.

OBJECTIVE: To evaluate the impact of maternal antibodies after challenge exposure of baby pigs with a homologous serovar of Haemophilus parasuis. ANIMALS: 7 gilts and their litters from a high health status farm. PROCEDURE: Gilts were vaccinated twice with a commercial bacterin that contained H parasuis serovar 4 and 5 or, as a control, adjuvant only. A group of pigs was also vaccinated similarly before challenge exposure. After early and late challenge exposure at 3 and 4 weeks, respectively, all pigs from vaccinated gilts were evaluated for clinical signs of infection, lesions, and antibody titer. RESULTS: All pigs coming from control gilts had severe signs of H parasuis infection. Macroscopic lesions included polyserositis and pneumonia, and bacteriologic examination confirmed H parasuis as the etiologic agent. Vaccinated pigs born to vaccinated gilts did not have clinical signs of disease. However, some vaccinated pigs born to control gilts had signs of nervous system dysfunction and lameness. There was no difference in lesion scores between early or late challenge exposure, but lesions scores for pigs from vaccinated and control gilts were different (P < 0.01). CONCLUSIONS: Under these experimental conditions, immune-naive and vaccinated pigs from vaccinated gilts were protected against systemic lesions when challenge exposed with a virulent strain of H parasuis. CLINICAL RELEVANCE: Vaccination of the gilt and pigs protects the latter from polyserositis, but results are not different from those for nonvaccinated pigs from vaccinated gilts. Maternal antibodies did not seem to interfere with vaccination of pigs at 1 and 3 weeks of age.

Animals↗
PubMed1998

Particle nucleation in the tropical boundary layer and its coupling to marine sulfur sources

New particle formation in a tropical marine boundary layer setting was characterized during NASA's Pacific Exploratory Mission-Tropics A program. It represents the clearest demonstration to date of aerosol nucleation and growth being linked to the natural marine sulfur cycle. This conclusion was based on real-time observations of dimethylsulfide, sulfur dioxide, sulfuric acid (gas), hydroxide, ozone, temperature, relative humidity, aerosol size and number distribution, and total aerosol surface area. Classic binary nucleation theory predicts no nucleation under the observed marine boundary layer conditions.

Journal Article↗