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Biomedical subjects

B Zhang

Publications and source records attributed to B Zhang.

At least 559 records · Page 31Linked to original sources
PubMed1995

[Diagnosis and management on acute coronary artery occlusion in valve replacement surgery: a report of four cases].

This paper reported four cases of acute coronary artery occlusion occurred during valve replacement procedure. Case 1 was of Marfan's syndrome who underwent Cabrol procedure. Case 2 was of congenital aortic bileaflet malformation with severe regurgitation and simple right coronary artery, who received the procedure of AVR. Both cases 3 and 4 suffered from rheumatic valve disease who were given DVR and tricuspid valve annuloplasty. All the cases had acute left coronary artery occlusion and did not revive after removal of aortic cross-clamp, which were immediately corrected by coronary bapass grafts from aortic to left descending branch with saphonous veins. All the patients successfully weaned from asistant circulation. Two cases survived. The causes of acute coronary artery occlusion were analyzed and the diagnostic methods and management introduced.

Acute Disease↗
PubMed1995

[Pre-operative radiotherapy for N0 supraglottic carcinoma: a randomized study].

A randomized study on 100 patients of N0 supraglottic squamous cell carcinoma with at least 3 years of follow-up was performed. Surgery alone was used in 56 patients, and combined therapy in 46 patients. The neck failure occurred in 14 (26%) patients and 7 (15%) patients respectively, there was no statistically difference (P = 0.287). Neck failure was higher in T4 stage supraglottic carcinoma for controlling of regional recurrence.

Adult↗
PubMed1994

PI 3-kinase activation is required for insulin stimulation of glucose transport into L6 myotubes.

Phosphatidylinositol 3-kinase (PI 3-kinase) is acutely stimulated by insulin but its role in regulating glucose metabolism is still not fully understood. Insulin acutely stimulates glucose transport into L6 myotubes approximately 2-fold, and activates PI 3-kinase activity 2 to 3-fold. Wortmannin, an inhibitor of PI 3-kinase, blocked insulin stimulation of 2-deoxyglucose transport into the myotubes in a time and dose-dependent manner. Inhibition was observed within 5 minutes and was complete by 30 minutes. The IC50 for this inhibition was approximately 10 nM; almost complete inhibition was observed at 100 nM. Similarly, insulin stimulation of PI 3-kinase activity was inhibited by wortmannin in a dose-dependent manner. The insulinmimetic vanadate activated hexose transport into the myotubes to more than 50% of the maximal level attained with insulin. Only approximately 60% of vanadate-activated glucose transport was inhibited by maximal wortmannin concentrations. It is concluded that insulin activation of PI 3-kinase is necessary for stimulation of glucose transport into L6 muscle cells. In contrast, vanadate appears to augment transport by acting upon PI 3-kinase-dependent and independent pathways.

Androstadienes↗
PubMed1994

Characteristics of the paramagnetic 1H-NMR spectra of the ferricytochrome c-551 family.

Heme proton resonances have been assigned for ferricytochromes c-551 isolated from four distinct species of bacteria. While the available structure information indicates that the four cytochromes have very similar conformations in solution, including the chirality of the methionine ligand sulfur bond, the chemical shifts of the paramagnetically shifted resonances are surprisingly different, more so than has been previously reported for a homologous series of ferricytochromes. The resonances are contrasted in terms of chemical shift and the temperature dependence of the shift, which gives rise to a very strong anti-Curie effect for some specific protons. Non-methyl heme resonances do display an approximately conserved set of chemical shifts, but the heme methyl groups demonstrate a wide range of values. The 12(1) heme methyl group is always the highest frequency heme methyl, but the relative positions of the other methyl groups may change. The 7(1) heme methyl group always displayed strong anti-Curie behavior, while the 12(1) methyl group displayed normal Curie behavior. The behavior of the other methyl groups was variable. Possible reasons for the range of observations will be discussed. In spite of their NMR differences, all the ferricytochromes c-551 demonstrated comparable electron-transfer rates to a membrane-bound cytochrome reductase system.

Bacterial Proteins↗
PubMed1994

Potentiation of insulin stimulation of phosphatidylinositol 3-kinase by thiazolidinedione-derived antidiabetic agents in Chinese hamster ovary cells expressing human insulin receptors and L6 myotubes.

Thiazolidinedione derivatives are insulin-sensitizing agents with proven antidiabetic activities in vivo. To explore the mechanism of action of this class of compounds, the effects of pioglitazone, CP-86,325, and AD-5075 on elements of the insulin signal transduction pathways were studied in Chinese hamster ovary cells overexpressing human insulin receptor (CHO.T) and L6 myotubes. In CHO.T cells, the binding of insulin to its receptor and the insulin-stimulated tyrosine kinase activity of the receptor were not altered by pioglitazone or CP-86,325. In contrast, treatment of CHO.T cells with the compounds resulted in significant increases in insulin-stimulated phosphatidylinositol (PI) 3-kinase activity. This insulin-enhancing effect was also observed in L6 myotubes treated with CP-86,325. The augmentations in kinase activity observed in CHO.T cells correlated with increases in the amount of PI 3-kinase (p85 subunit) in anti-phosphotyrosine immunoprecipitates of cell lysates. No gross changes in the tyrosine phosphorylation state of the insulin receptor substrate-1 were detected in insulin-stimulated CHO.T cells following treatment with the compounds. Furthermore, the compounds did not enhance insulin stimulation of mitogen-activated protein kinase or DNA synthesis in CHO.T cells. Thus, thiazolidinedione-derived antidiabetic agents may act as insulin sensitizers by augmenting insulin stimulation of PI 3-kinase activity in a rather specific manner.

Animals↗
PubMed1994

ocs element promoter sequences are activated by auxin and salicylic acid in Arabidopsis.

ocs elements are a group of promoter elements that have been exploited by two distinct groups of plant pathogens, Agrobacterium and certain viruses, to express genes in plants. We examined the activity of single and multiple ocs elements linked to a minimal plant promoter and the uidA reporter gene in transgenic Arabidopsis. beta-Glucuronidase activity was detected only in root tips and in callus tissue after auxin treatment. A more sensitive assay revealed that auxin treatment also increased ocs element activity in aerial parts of the plant, although the absolute levels of ocs element activity were greater in roots. The response of ocs elements to exogenous auxin began within 1 h. Salicylic acid, a disease-resistance signal in plants, also increased ocs element activity in both roots and aerial parts of the plant. The question of whether the induction in ocs element activity is mediated through auxin and/or salicylic acid signal transduction pathways or is part of a more general stress response is discussed.

Arabidopsis↗
PubMed1994

Effect of dietary protein on the liver content and subunit composition of the branched-chain alpha-ketoacid dehydrogenase complex.

Levels of expression of two subunits of the liver branched-chain alpha-ketoacid dehydrogenase complex in response to extremes of dietary protein intake (50% versus 0% protein diet) were determined by quantitative immunoblotting. Dietary protein deficiency decreased the amount of E1 alpha protein to a greater extent than E2 protein. The ratio of E1 alpha to E2 was below 1 in the liver of animals starved for protein and above 1 in the liver of animals fed the high-protein diet. Supplementation of the 0% protein diet with 5% leucine (but not 5% valine) had the same effect as the 50% protein diet. The extremes of dietary protein also resulted in a divergent pattern of expression of the mRNAs for the subunits of the complex. The E1 beta message showed the expected corollary of being greater in the liver of the high-protein-fed rats than the no-protein-fed rats. In contrast, the E2 message was not affected by the two extremes of dietary protein and the E1 alpha message was greater in the liver of the no-protein-fed rats than the high-protein-fed rats. Thus, coordinate regulation of gene expression of the subunits of the complex does not occur in response to dietary protein. Post-transcriptional regulatory mechanisms most likely determine the amount of the complex and the ratio of its subunits. The decrease in E1 alpha/E2 protein ratio that occurs in dietary protein deficiency may increase sensitivity of the complex to phosphorylation-mediated inhibition by branched-chain alpha-ketoacid dehydrogenase kinase.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1994

In vitro conversion of recombinant human proapolipoprotein A-I to apolipoprotein A-I.

We recently investigated the in vivo conversion of recombinant human proapolipoprotein A-I (rh-Met-proapo A-I) from E. coli to apolipoprotein (apo) A-I in rabbits. In vitro incubation of rh-Met-proapo A-I with rabbit serum produced mature apo A-I3 isoproteins, as determined by the immunoblotting method. However, at the time we were unable to chemically confirm a newly produced protein band which appeared at the position of human apo A-I3. Since then, we have confirmed the amino acid sequence of the protein using a membrane protein sequence technique, and have concluded that it corresponds to human apo A-I3.

Amino Acid Sequence↗
PubMed1994

Healing of a severe microarterial trauma: an experimental study.

A severe microarterial trauma (arteriotomy/intimectomy) was introduced to the central arteries of rabbit ears. Twenty-one patent vessels, 3 at each interval of 2 hours, 1, 3, 7, 14, 30, and 90 days after reperfusion were taken for light and scanning electron microscopy studies. These vessels remained patent at all time intervals. A physiological "in vivo" perfusion technique with fixation fluid of normal temperature (37 degrees C), pressure (120 mm Hg) and osmolarity (300 mOsm) was used to ensure fixed relaxed vessels. The endothelial, internal elastic, and part of the medial layers of vessel walls were removed following intimectomy. The inner surface of the intimectomy region was irregular and partly covered with thrombotic materials between 2 hours and 3 days postreperfusion. Endothelialization of the traumatized region was first observed at 3 days and was completed between 7 and 14 days. Intimal hyperplasia developed during this period and had not diminished in thickness by 30 or 90 days. The trauma and healing process of the arteriotomy/intimectomy are similar to the healing of vascular anastomoses and virtually identical to the clinical trauma of vessel avulsion, but neointima formation is more pronounced and engages vessel walls far outside the intimectomy site.

Animals↗
PubMed1994

Quantitative characterization of insulin-glucose response in Watanabe heritable hyperlipidemic and cholesterol-fed rabbits and the effect of cilazapril.

A great deal of evidence suggests that insulin resistance, via hyperinsulinemia, contributes to hyperlipoproteinemia and coronary atherosclerosis. When Watanabe heritable hyperlipidemic (WHHL) rabbits, an animal model of familial hypercholesterolemia (FH), are compared with normolipidemic Japanese White (JW) rabbits, an elevated fasting plasma insulin level and a heightened plasma insulin response to an intravenous (i.v.) glucose challenge are found. To elucidate the mechanism behind this phenomenon, a two-compartment model of the glucose/insulin system was fitted to empirical time courses of glucose and insulin concentrations during an i.v. glucose tolerance test (IVGTT) by nonlinear least-square regression, and the model parameters such as the glucose utilization rate constant, insulin degradation rate constant, and pancreas sensitivity were determined. WHHL rabbits showed decreased values of glucose utilization and insulin degradation rate constants and slightly higher values of pancreas sensitivity. This suggests that insulin resistance occurs in extrapancreatic tissues, and that this may be attributable to insulin receptor and/or post-insulin receptor abnormalities. Cholesterol feeding did not significantly change glucose tolerance or insulin action in JW rabbits. The effects of an angiotensin-converting enzyme (ACE) inhibitor, cilazapril, on insulin resistance were also examined in WHHL and JW rabbits. A decreased insulin response to an i.v. glucose challenge and increased glucose utilization and insulin degradation rate constants were observed in WHHL rabbits that had been treated with cilazapril, indicating that cilazapril improved insulin resistance in WHHL rabbits, possibly by increasing the number of insulin receptors. No significant differences were found in glucose tolerance and insulin action in JW rabbits before and after cilazapril administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

A preliminary epidemiological study of the patient population visiting an urban ED in the Republic of China.

The objective of this study was to evaluate the characteristics of the patient population of an urban emergency department (ED) in The People's Republic of China. A prospective observational study was conducted at a university-affiliated hospital adult ED medical unit and included all patients visiting the medical unit of the ED during a 2-week period. A data collection log was designed and placed in the ED. Data were recorded by the attending ED physician for all patients presenting during the study period. There were 569 patients recorded in the 2-week period. The major presenting complaints were fever (20.9%), abdominal pain (20.1%), and chest pain (11.4%). The most common diagnosis were upper respiratory tract infection (11.6%), angina pectoris (6.3%), and acute gastritis (4.9%). Eight percent of the patients were admitted, 29.0% were held in an observation unit, and 0.6% died. The average length of stay in the ED observation unit was 5.6 days. These data offer emergency physicians a preliminary understanding of the clinic presentations and diagnoses of patients seen in a university-affiliated urban hospital ED in China. The number and length of time patients were held in observation unit point out the shortage of in-hospital beds. This study is useful for describing and understanding characteristics of the patient encounter and for improving the delivery of emergency care in China.

Adolescent↗
PubMed1994

A reference method for correlation of anatomic and functional brain images: validation and clinical application.

We describe a reference device that provides accurate correlation between anatomic and functional brain images. The reference device, which generates fiduciary reference points on sequential scan planes, is positioned adjacent to the canthomeatal line of the subject and held in place by a glasses-like framework anchored to the external auditory meatus. The reference system was tested on 17 subjects undergoing 99mTc hexamethylpropylene amine oxime ([99mTc]HMPAO) brain single-photon emission computed tomography (SPECT) and cranial computed tomography (CT) scans. The centers of the caudate nuclei, thalami, brain stem, and cerebellar vermis were identified independently on CT and SPECT. The average difference +/- 1 SD between structure locations (x, y, and z) on SPECT and CT were calculated as 1.86 +/- 1.5, 2.16 +/- 1.4, and 1.83 +/- 1.9 mm, respectively. The clinical application of the method is showed by coregistration of images from SPECT to MRI. An example of sequential [99mTc]HMPAO brain SPECT scan sections precisely coregistered with MRI scan sections oriented parallel to and sequentially above the canthomeatal line illustrates the correlation between regional cerebral blood flow (rCBF) tracer activity on SPECT and normal anatomic structures. Test-retest activation paradigms in brain SPECT requires precise SPECT-to-SPECT image coregistration to evaluate changes in rCBF during activation. Precisely coregistered rest, 48-hour repeat rest [99mTc]HMPAO SPECT studies are shown to illustrate the normal intrasubject variability of tracer uptake. An example of the usefulness of image coregistration for evaluation of viable residual brain tumor and its application to tumor biopsy is presented. An example of developmental abnormalities identified by [99mTc]HMPAO brain SPECT is illustrated by a case of autistic disorder. An example of image coregistration in stroke and evaluation of cerebrovascular disease with Diamox (Lederle Laboratory Division, Pearl River, NY) cerebrovasculature stress testing is presented. The usefulness in epilepsy using a protocol whereby the tracer is injected during the ictal phase of seizure is presented. We conclude that the reference system provides an accurate, rapid, and noninvasive patient-specific method for correlating brain structure with brain function.

Adolescent↗
PubMed1994

The inducible production of nitric oxide by articular cell types.

Nitric oxide (NO) may play a role in tissue remodeling associated with arthritis. The articular cell sources of human inducible NO synthesis, however, have not been defined. This study demonstrates that human articular chondrocytes in primary or organ culture, but not synovial fibroblasts, produce NO in response to catabolic cytokines such as interleukin-1 (IL-1). As measured by the accumulation of NO2- in culture medium, NO production by IL-1-stimulated chondrocytes was inhibited by the NO synthase inhibitor Ng-monomethyl-L-arginine (NMA) and dependent on the presence of exogenous L-arginine. Other inflammatory cytokines such as tumor necrosis factor, but not transforming growth factor-beta, induced chondrocyte NO synthesis. The stimulation of NO synthesis required both RNA and protein synthesis. Chondrocytes isolated from cartilage derived from osteoarthritic patients also produced large amounts of NO in response to IL-1. In beginning to define potential effects of NO on chondrocyte function, it is shown that IL-1 induced an increase in cyclic guanosine monophosphate (cGMP) which was inhibited by NMA. In summary, these results demonstrate that cytokine-induced production of NO is a response of human articular chondrocytes but not of synovial fibroblasts. A potential role of NO in cytokine-induced tissue remodeling in the joint is provided by the induction of cGMP.

Cartilage, Articular↗