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Biomedical subjects

Z Jiang

Publications and source records attributed to Z Jiang.

341 records · Page 19Linked to original sources
PubMed1983

Acyl-CoA oxidase from Candida tropicalis.

Acyl coenzyme A oxidase (acyl-CoA oxidase) has been isolated in good yield from Candida tropicalis pK 233 grown on n-alkanes. Gel filtration, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and measurement of flavin content suggest that the oxidase is an octamer of Mr 75 000 subunits each containing one flavin. The oxidase yields the red semiquinone form on dithionite or photochemical reduction, slowly forms an N-5 adduct with 0.16 M sulfite at pH 7.4, and is rapidly reduced by borohydride, forming the 3,4-dihydroflavin isomer. The red flavosemiquinone is only kinetically stabilized with respect to disproportionation in the free enzyme but is thermodynamically stabilized on binding enoyl-CoA derivatives. The enzyme is reduced by butyryl-, octanoyl-, and palmitoyl-CoA without formation of prominent long-wavelength bands. Acyl-CoA oxidase and the acyl-CoA dehydrogenases share many similarities in their interaction with CoA derivatives. For example, both enzymes stabilize the anionic radical on binding enoyl-CoA derivatives, both dehydrogenate 2-oxoheptadecyldethio-CoA but cannot utilize S-heptadecyl-CoA, both form long-wavelength bands with CoA persulfide species, and both enzymes are attacked by the suicide substrates 3,4-pentadienoyl-CoA and (methylene-cyclopropyl)acetyl-CoA at the flavin prosthetic group.

Acyl-CoA Oxidase↗
PubMed1982

Substance P: a putative sensory transmitter in mammalian autonomic ganglia.

Repetitive presynaptic stimulation elicited slow membrane depolarization in neurons of inferior mesenteric ganglia from guinea pigs. This response was not blocked by cholinergic antagonists but was specifically and reversibly inhibited by a substance P analog, (D-Pro2, D-Phe7, D-Trp9)-substance P, which also depressed the depolarization induced by exogenously applied substance P. The atropine-sensitive slow excitatory and slow inhibitory postsynaptic potentials evoked in neurons of rabbit superior cervical ganglia were not affected by the substance P analog. These and previous results provide strong support for the hypothesis that substance P or a closely related peptide is the transmitter mediating the slow depolarization. The latter may represent a sensory input from the gastrointestinal tract to neurons of the prevertebral ganglia.

Action Potentials↗
PubMed1981

A comparison of the effects of flurazepam on gamma-aminobutyric acid mediated depression of cerebellar and cerebral cortical neurons.

With standard extracellular recording and microiontophoretic techniques, the effects of flurazepam on gamma-aminobutyric acid (GABA) evoked depression of cerebellar and cerebral cortical neurons in rats have been studied. It was found that although flurazepam potentiated the GABA-mediated inhibition of most Purkinje cells (25 or 36), it caused only a weak potentiation of GABA action on some cerebral cortical neurons (14 of 37). The difference between the action of flurazepam in these two structures was statistically significant. The results confirm a previous report that the enhancement of GABA-evoked inhibition by benzodiazepines is more readily elicited on cerebellar cortical neurons than on cerebral cortical neurons.

Action Potentials↗
PubMedDate not supplied

Computer-assisted neurosurgery system: Wayne State University hardware and software configuration.

Computer-assisted neurosurgery uses the latest technological advancements in imaging, computers, mechanics, and electronics to improve the accuracy and reduce the invasiveness and risk of neurosurgical procedures. We describe the Wayne State University, Detroit, Michigan, computer-assisted neurosurgical system with the emphasis on software and discuss the theory guiding the development of this system and its application in real-time position tracking systems. Our system consists of the Neurological Surgery Planning System (NSPS) software which we developed at our medical center and three types of position tracking systems: the Zamorano-Dujovny (Z-D) are digitizer for frame-based procedures, an articulated arm, and an infrared-based digitizer for frameless procedures. The NSPS software is designed to offer neurosurgeons a safe and accurate method to approach intracranial lesions by preoperatively planning a surgical trajectory. Software consisting of the most advanced technologies in computer vision, computer imaging/graphics, and stereotactic numeric analysis forms the core of the system. Capabilities for correlating data from imaging studies to facilitate image reconstruction, image mapping, and three-dimensional (3D) visualization of target volumes enable the neurosurgeon to simulate surgical procedures into a preoperative protocol to be used during surgery, both to follow the preplanned trajectory and to track the position of surgical instruments in real-time on the computer monitor. The tracking systems position and orient the surgical instruments relative to the patient's head. With these devices, the display of the surgical instruments together with the virtual images create an excellent intraoperative tool.

Algorithms↗
PubMedDate not supplied

Toward a dog radiation hybrid map.

Dog fibroblasts grown from a biopsy performed in a male mongrel were fused after gamma irradiation with thymidine kinase-deficient hamster cells and cultivated in selection medium. A total of 148 clones were obtained and screened by means of PCR amplification using primers corresponding to a dog-specific short repetitive element and to dog microsatellites and genes. One hundred seven cell lines were selected and grown in roller bottles and the distribution of 39 markers was analyzed in the extracted DNA. The results clearly indicate that this panel of hybrid cell lines should prove invaluable for constructing a map of the canine genome. In parallel, for more than 500 microsatellites present in the databases or screened from two libraries of short inserts, we have determined PCR conditions favoring dog-specific products even in the presence of hamster DNA. These highly polymorphic microsatellites should be useful in further linkage studies. We have also characterized 254 markers: dog genes, human expressed sequenced tags (huESTs), and traced orthologous amplified sequenced tags (TOASTs). Once mapped, these will constitute powerful tools to detect regions of conserved synteny in human and other mammalian genomes.

Animals↗
PubMedDate not supplied

Design and assembly of an 8 tesla whole-body MR scanner.

PURPOSE: The purpose of this report is to describe the design and construction of an 8 T/80 cm whole-body MRI system operating at 340 MHz. METHOD: The 8 T/80 cm magnet was constructed from 414 km of niobium titanium superconducting wire. The winding of this wire on four aluminum formers resulted in a total inductance of 4,155 H. Gradient subsystems included either a body gradient or a head gradient along with a removable shim insert. The magnet and gradient subsystems were interfaced to two spectrometers. These provided the control of the gradient amplifiers and the two sets of four RF power amplifiers. The latter provide in excess of 8 kW of RF power from 10 to 140 MHz and 10 kW of RF power from 245 to 345 MHz. A dedicated computer-controlled patient table was designed and assembled. The entire system is located in a clinical setting, facilitating patient-based studies. RESULTS: The 8 T/80 cm magnet was energized without complication and achieved persistent operation using 198.9 A of current, thereby storing 81.5 MJ of magnetic energy. Exceptional performance was observed for nearly all components both in isolation and when combined within the complete system. CONCLUSION: An 8 T/80 cm MRI system has been assembled. The magnet subsystem is extremely stable and is characterized by good homogeneity and acceptable boil-off rates.

Aluminum↗
PubMedDate not supplied

Serum antibody response induced in mice after oral administration of three different antigens of enterotoxigenic Escherichia coli in enteric coated microparticles.

BACKGROUND: Gastric digestion of these antigens plays an important role, decreasing the ability to deliver antigens to the gut-associated lymphoid tissue. To overcome this obstacle, microencapsulated antigens from enterotoxigenic Escherichia coli (ETEC) were evaluated for oral immunization of mice. METHODS: Four groups of 10 each received 3 series of 3 doses each of (1) B subunit of cholera toxin (CTB), similar to heat-labile toxin of ETEC, (2) formalin-killed whole cell ETEC H10407 (FK-ETEC), (3) crude preparation of colonization factor antigen I (CFA/I), or (4) placebo. Serum antibody was measured on day 0 and 60 by ELISA. RESULTS: In group 1 a CTB antibody response was induced in all mice, 3 with 1:105 titer and 7 with 1:106. These antibodies neutralized cholera toxin-induced steriodogenesis of Y-1 adrenal cells. In group 2, 8 mice developed a whole H10407 bacteria antibody titer of 1:100, one 1:200 and one showed no immune response. In the same group, an anti-CFA/I response was observed in 6 mice and anti-LPS in 4 mice as determined by Western blot. All mice in group 3 showed > 1:104 anti-CFA/I antibody titer. Group 4 mice did not develop an immune response to any ETEC antigens. CONCLUSIONS: Microencapsulation appears to be a suitable approach for oral vaccination against ETEC and Vibrio cholerae.

Animals↗
PubMedDate not supplied

Transmission electron microscopic study of the hemorrhagic spots in patients with epidemic hemorrhagic fever in the early stage.

Epidemic hemorrhagic fever (EHF) virus particles were found in the squamous epithelial cells and the capillary endothelial cells of the petechial spots located on the mucous membrane of the soft palate in 3 patients with severe early-stage EHF with transmission electron microscopy. The virus particles were round or oval in shape, about 100 nm in diameter, with a two-layer lipid envelope from which spikes were protruding. The nucleocapsid of the virus appeared to be hollow microfilamentoid or dense granules. Meanwhile, budding virus particles with a diameter of 80 nm were found in the enlarged Golgi apparatus. The infected cells displayed an enlarged and proliferating Golgi apparatus. The morphological characteristics of the viron mentioned above coincided with those of the virus particles of the family Bunyaviridae. This study is the first to demonstrate that the squamous epithelial cells on the mucous membrane of the soft palate are the target cells of EHF infection and to provide subcellular morphological evidence of petechial hemorrhage at the soft palate.

Adult↗
PubMedDate not supplied

Evaluating a computer-based experiential learning simulation: a case study using criterion-referenced testing.

A case study of a computer-based experiential learning program involving the use of criterion-referenced testing as a quantitative evaluation tool is described. The simulation was designed to introduce nurses to basic computer operations. One hundred and thirty-eight nurses participated in the evaluation using a specially prepared version of the program that recorded the time required to perform actions, the number of unsuccessful attempts to complete instructions, and the number of correct responses to specific questions. The ability of the nurses to "drag and drop" increased significantly from less than 20% to more than 90% (p < .05, Student's t-test). Their knowledge of the definitions of four computer-related terms (i.e., trackball, desktop, window, and icon) increased significantly (from 65% to 80%, p < .1). In subjective evaluations, 82% of respondents reported that they enjoyed the lesson and 89% wanted more computer-based instructional units to be developed. Use of criterion-referenced testing helped to shed new light on the utility of such computer aided instructional systems.

Academic Medical Centers↗
PubMedDate not supplied

Consumption of n-3 polyunsaturated fatty acid-enriched eggs and changes in plasma lipids of human subjects.

The cholesterolemic effect of chicken eggs enriched with n-3 polyunsaturated fatty acids (PUFA) was investigated in healthy volunteers. Twenty-three male university students consumed two regular or n-3 PUFA-enriched eggs per day with their habitual diet for 18 days. Plasma total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels were raised in subjects who consumed regular eggs but were maintained virtually unchanged in those who consumed n-3 PUFA-enriched eggs. Intake of two regular eggs a day did not affect plasma high-density lipoprotein cholesterol (HDL-C) and plasma triglyceride (TG) levels, but intake of two n-3 PUFA-enriched eggs a day resulted in a significant elevation in HDL-C (p < 0.05) and a reduction in plasma TG (p < 0.01). Consuming regular eggs tended to decrease both HDL-C/TC and HDL-C/LDL-C ratios, whereas consuming n-3-enriched eggs tended to increase them. The n-3 PUFA contents in plasma lipids of subjects who consumed n-3 PUFA-enriched eggs were also found to be elevated. These results demonstrate that the cholesterolemic property of chicken eggs can be modified by altering the fatty acid composition of yolk lipids.

Adolescent↗
PubMedDate not supplied

Maternal-fetal transfer of metallic mercury via the placenta and milk.

To clarify the situation of trans-placental movement and milk screening of metallic mercury in human, the content of mercury was detected in the maternal blood, umbilical cord blood, milk, and placental tissues. In 18 parturient women, 9 had been occupationally exposed to metallic mercury whereas the other 9 had not. Mercury was detected by means of cold vapor atomic absorption spectrophotometry. Results showed that the concentrations of mercury of the umbilical cord blood and placental tissues were higher than that of maternal blood. The ratio of organic and total mercury of milk was markedly lower than that of maternal blood in the exposed group (P < 0.01). The ratio of inorganic to total mercury of milk was significantly higher than that of maternal blood (P < 0.01). Therefore, this study concluded that the metallic mercury can be transferred to the fetus via the placenta and secreted to a newborn via milk.

Adult↗