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Biomedical subjects

Jun Zhang

Publications and source records attributed to Jun Zhang.

440 records · Page 25Linked to original sources
PubMedDate not supplied

SK&F 95654-induced acute cardiovascular toxicity in Sprague-Dawley rats--histopathologic, electron microscopic, and immunohistochemical studies.

The characteristics and pathogenesis of the cardiovascular toxicity induced by the type III selective phosphodiesterase inhibitor SK&F 95654 were examined in 2 studies. Sprague-Dawley rats received either a single sc injection of 50, 100, or 200 mg/kg SK&F 95654 and were euthanized at 24 hours after administration of the drug (Study 1), or were given a single subcutaneous (sc) injection of 100 mg/kg SK&F 95654 and euthanized at 1, 2, 4, 6, 8,12, 24 hours, or 2 weeks after treatment (Study 2). Control rats received either DMSO or saline. Myocardial lesions and vascular lesions of the mesentery, spleen, and pancreas were seen 24 hours after dosing with either 50,100, or 200 mg/kg SK&F 95654. The frequency and severity of these lesions (evaluated after the 100 mg/kg dose) increased with time over a period of 1 to 24 hours. By 2 weeks, the lesions subsided. Cardiac lesions consisted of myocyte necrosis with hypercontraction bands, inflammatory cell infiltration, interstitial hemorrhage, and interstitial edema. Vascular lesions of the mesentery were most prominent and consisted of vasodilatation and inflammation in the small-sized vessels, arterial medial necrosis and hemorrhage, and venous thrombosis. The vascular lesions included: leukocyte adhesion to endothelial cells, transendothelial migration of leukocytes, and inflammatory cell infiltration into vessel walls. Affected vessels included arteries, terminal arterioles, capillaries, postcapillary venules, and veins. Apoptosis of endothelial and smooth muscle cells was detected in the mesenteric vasculature by both TUNEL assay and electron microscopy. Evidence of endothelial cell activation in the mesenteric arteries and veins was also observed by electron microscopy. Immunohistochemical staining detected enhanced endothelial cell expression of intercellular adhesion molecule- 1 (ICAM- 1) and von Willebrand factor (vWF) in the mesenteric arteries and veins. Mast cells were noted to be more prevalent in affected mesenteric tissue from drug-treated animals. The present findings suggest that apoptosis of endothelial and smooth muscle cells, activation of endothelial cells, recruitment of mast cells, and increased expression of adhesion molecules are important factors to the overall pathogenesis of SK&F 95654-induced vasculitis.

Animals↗
PubMedDate not supplied

Determination of burn depth by polarization-sensitive optical coherence tomography.

An assessment of burn depth is a key step in guiding the treatment of patients who have sustained thermal injuries. Polarization-sensitive optical coherence tomography (PS-OCT) might eventually provide the physician with a quantitative estimate of actual burn depth. Burns of various depths were induced by contacting rat skin with a brass rod preheated to 75 degrees C for 5, 15, or 30 s. Thermal injury denatured the collagen in the skin, and PS-OCT imaged the resulting reduction of birefringence through the depth-resolved changes in the polarization state of light propagated and reflected from the sample. Stokes vectors were calculated for each point in the PS-OCT images and the reduction in the rate of phase retardation between two orthogonal polarizations of light (deg/microm) was found to show a consistent trend with burn exposure time. PS-OCT is a noninvasive technique with potential to give the physician the information needed to formulate an optimal treatment plan for burn patients.

Animals↗
PubMedDate not supplied

Noninvasive imaging of oral premalignancy and malignancy.

Early detection of cancer and its precursors remains the best way to ensure patient survival and quality of life. Our specific aim is to test a multimodality approach to noninvasive diagnostics of oral premalignancy and malignancy. In the hamster cheek pouch model (120 hamsters), in vivo optical coherence tomography (OCT) and optical Doppler tomography (ODT) map epithelial, subepithelial, and vascular change throughout carcinogenesis. In vivo multiwavelength multiphoton (MPM) and second-harmonic generated (SHG) fluorescence techniques provided parallel data on surface and subsurface tissue structure, specifically collagen presence and structure, cellular presence, and vasculature. Images are diagnosed by two blinded, prestandardized investigators using a scale from 0 to 6 for all modalities. After sacrifice, histopathology is evaluated on a scale of 0 to 6. Imaging data are reproducibly obtained with good accuracy. Carcinogenesis-related structural and vascular changes are clearly visible to tissue depths of 2 mm. Sensitivity (OCT/ODT alone, 71 to 88%; OCT+MPMSHG, 79 to 91%) and specificity (OCT alone, 62 to 83%; OCT+MPMSHG, 67 to 90%) compare well with conventional techniques. Our conclusions are that OCT/ODT and MPM/SHG are promising noninvasive in vivo diagnostic modalities for oral dysplasia and malignancy.

Animals↗
PubMedDate not supplied

Noninvasive diffuse optical measurement of blood flow and blood oxygenation for monitoring radiation therapy in patients with head and neck tumors: a pilot study.

This pilot study explores the potential of noninvasive diffuse correlation spectroscopy (DCS) and diffuse reflectance spectroscopy (DRS) for monitoring early relative blood flow (rBF), tissue oxygen saturation (StO(2)), and total hemoglobin concentration (THC) responses to chemo-radiation therapy in patients with head and neck tumors. rBF, StO(2), and THC in superficial neck tumor nodes of eight patients are measured before and during the chemo-radiation therapy period. The weekly rBF, StO(2), and THC kinetics exhibit different patterns for different individuals, including significant early blood flow changes during the first two weeks. Averaged blood flow increases (52.7+/-9.7)% in the first week and decreases (42.4+/-7.0)% in the second week. Averaged StO(2) increases from (62.9+/-3.4)% baseline value to (70.4+/-3.2)% at the end of the second week, and averaged THC exhibits a continuous decrease from pretreatment value of (80.7+/-7.0) [microM] to (73.3+/-8.3) [microM] at the end of the second week and to (63.0+/-8.1) [microM] at the end of the fourth week of therapy. These preliminary results suggest daily diffuse-optics-based therapy monitoring is feasible during the first two weeks and may have clinical promise.

Aged↗
PubMedDate not supplied

Use of polarization-sensitive optical coherence tomography to determine the directional polarization sensitivity of articular cartilage and meniscus.

The directional polarization sensitivity of articular cartilage and meniscus is investigated by use of polarization-sensitive optical coherence tomography (PS-OCT) by varying the angle of incident illumination. Experimental results show that when the incident light is perpendicular to the tissue surface, normal articular cartilage demonstrates little polarization sensitivity, while meniscus demonstrates strong polarization sensitivity. Differences in optical phase retardation produced by articular cartilage and meniscus are observed when the incident angle of the scanning light beam is adjusted between 0 and 90 deg relative to the tissue surface. Directional polarization sensitivity of articular cartilage and meniscus as obtained by PS-OCT imaging using variations in the angle of incident illumination can be used to assess the orientation and organization of the collagen matrix of these tissues. The polarization sensitivity as evidenced by the Stokes vector and optical phase retardation images can be explained by the orientation of the angle of illumination relative to the unique structural organization of the collagen fibrils and fibers of articular cartilage and meniscus.

Animals↗
PubMedDate not supplied

Quality of life in women undergoing medical treatment for early pregnancy failure.

OBJECTIVES: To examine predictors of quality of life, depression, and stress in women undergoing medical management of early pregnancy failure with misoprostal and to assess the relationship of quality of life, depression, and stress to treatment acceptability. DESIGN: Descriptive observational study of women undergoing medical management of early pregnancy failure with misoprostol conducted as part of a multicenter pilot study testing the efficacy of saline-moistened versus dry application of vaginal misoprostol. Data were collected prior to treatment through 15 days posttreatment. SETTING: Four university-based hospitals. PARTICIPANTS: Women (n = 80) < or = 1 weeks pregnant diagnosed with anembryonic gestation or fetal demise. INTERVENTION: Vaginal misoprostol for medical evacuation. MAIN OUTCOME MEASURES: Quality of life (physical role functioning, emotional role functioning, social functioning, vitality, and bodily pain), depression, stress, and treatment acceptability. RESULTS: Women who received medical evacuation demonstrated poorer quality of life than same-age published population norms, scoring 0.25 to 0.78 of a standard deviation below the population mean for four of the five subscales. CONCLUSIONS: Nurses should assist patients to minimize and manage physical symptoms during treatment for early pregnancy failure. Women with higher external demands and lower social/tangible support may need greater assistance.

Abortifacient Agents, Nonsteroidal↗
PubMedDate not supplied

Physician survey on knowledge and reporting practices of transfusion-transmitted infections in Canada.

OBJECTIVE: To assess physicians' knowledge and reporting practices of transfusion-transmitted infections (TTI). DESIGN: Cross-sectional postal survey. TARGET POPULATION: Family physicians and specialists. METHODS: A survey questionnaire was sent by mail to 1,359 randomly selected physicians across Canada, and was followed up by a reminder telephone call. RESULTS: A total of 546 (40%) physicians completed and returned the questionnaire. The data from 512 eligible practitioners across Canada were analyzed. Almost all physicians were knowledgeable on the transmission of HIV, HBV and HCV through blood and plasma derivatives. However, physicians' knowledge, particularly the family physicians', was generally lower for less well-known TTIs. For example, only 7.2% of family physicians recognized Babesiosis as a TTI. Of the total 318 physicians who have encountered patients with possible TTI, 50% of them reported such cases to public health or other authorities and many reported to more than one organization. Of the total 159 non-reporting physicians, 91.1% explained that the cases were already reported by laboratories or other physicians. More than 90% of respondents think that it is important or very important that physicians report the cases of TTI to public health authorities for the purpose of surveillance, and more than 80% of them think that it is important or very important to include TTI as a separate entity in the communicable diseases surveillance systems. CONCLUSION: The majority of physicians recognize the more common TTIs and only 50% of them reported such cases. The majority of physicians support the reporting of TTI to public health authorities for surveillance. Recommendations are made to increase physicians' knowledge and reporting of TTI.

Canada↗