Biomedical subjects
Publications and source records attributed to J X Zhang.
Chemical investigation on an ethanol extract from the roots of Spiraea japonica var. acuta resulted in the isolation of three new diterpene alkaloids named spiramide (1) and spiratine A (2) and spiratine B (3). Structures of 1-3 were elucidated primarily on the basis of 1D and 2D NMR experiments.
Specific vasoactive substances such as endothelin (ET) have been proposed to induce heterogeneity of tissue perfusion and thus the oxygen delivery at the sinusoidal level in the liver, but a direct method for testing this hypothesis has not been available. Our objective was to develop a method to test the hypothesis that functional heterogeneity of blood flow can be induced at the sinusoidal level by mediators such as endothelin-1, which act at the sinusoidal level. We constructed oxygen-sensitive membranes using tris (1,10-phenanthroline) ruthenium (II) chloral hydrate, a dye whose fluorescence is quenched by oxygen incorporated into a silicon rubber membrane. The membrane (less than 40 microm thick) was formed on a glass coverslip that served as the viewing window of the system for in vivo fluorescence microscopy and allowed determination of the PO2 distribution in rat liver acini during intraportal infusion of ET or phenylephrine (PE) in vivo. Heterogeneity was quantified by comparing the coefficient of variation (CV) of the fluorescence intensity within the zone 1 before, during, and after drug infusion. PE and ET doses were matched to produce a similar increase in portal pressure. PE caused a gradient of PO2 across zones, but within zone 1 no significant increase in CV was observed. In contrast, ET produced a patchy pattern of both an increase and decrease in PO2 resulting in doubling (P < 0.01) in CV of fluorescence intensities within zone 1. These results indicate that PE, which acts at presinusoidal sites, results in a homogeneous decrease in tissue PO2 within a zone, while ET, which additionally acts at sinusoidal sites, induces significant microheterogeneity of tissue PO2. The oxygen-sensitive membrane provides a useful tool for oxygen mapping in vivo.
The present study was undertaken to investigate hepatic microcirculatory response following partial portal vein ligation (PPVL) in rats. Portal pressure was markedly increased 2-6 wk after PPVL, but no significant reduction in sinusoidal perfusion and hepatocellular injury were detected. However, marked neovascularization was observed in PPVL rats using intravital microscopy and scanning electron microscopy (SEM). Extremely high red blood cell velocity (2,000-4,900 microm/s) was seen in these vessels. Injection of fluorescein sodium via the carotid artery revealed that the neovessels originated from the hepatic arterial vasculature. This was further confirmed by clamping the common hepatic artery and phenylephrine injection from the carotid artery. These vessels maintained sufficient flow after massive sinusoidal shutdown elicited by the portal infusion of endothelin receptor B agonist IRL-1620. SEM also showed extensive neovascularization at the hilum. Additionally, clamping the portal vein decreased sinusoidal perfusion only by 9.5% in PPVL, whereas a 71.2% decrease was observed in sham. These results strongly suggest that the liver maintains its microcirculatory flow by vascular remodeling from the hepatic arterial vasculature following PPVL.
OBJECTIVE: This study was undertaken to determine the diagnostic test characteristics of the alcohol screening strategy recommended in the National Institute on Alcoholism and Alcohol Abuse (NIAAA) "Physicians' Guide to Helping Patients with Alcohol Problems." METHOD: A research interview was performed on patients who presented to one urban emergency department (N = 395; 61% women). It asked three alcohol consumption questions, the CAGE questionnaire, and about past alcohol problems. The NIAAA-recommended screen was considered positive for alcohol consumption in excess of 14 drinks per week or 4 drinks per occasion for men, or 7 drinks per week or 3 drinks per occasion for women, or a CAGE score of 1 or greater. A sample of patients (n = 250) received the Composite International Diagnostic Interview substance abuse module, a gold standard interview, to determine lifetime or prior 12-month alcohol abuse or dependence; results were adjusted for verification bias. RESULTS: The prevalence of lifetime:alcohol abuse or dependence was 13%, for which the NIAAA strategy was 81% sensitive and 80% specific. The prevalence of alcohol abuse or dependence in the prior 12 months was 10%, for which the strategy was 83% sensitive and 84% specific. Its positive likelihood ratio exceeded that of the CAGE, augmented CAGE or consumption questions alone, and its negative likelihood ratio was the lowest. CONCLUSIONS: The screening strategy combining alcohol consumption and CAGE questions recommended in the NIAAA "Physicians' Guide" is valid, and has superior test characteristics compared to the CAGE alone, in this predominantly black (86%) emergency department population. Its brevity and simple interpretation recommend wider dissemination of the NIAAA "Physicians' Guide," although future research should examine its test characteristics in other clinical settings and with other populations.
AIM: To identify hepatitis C virus(HCV) core protein epitopes recognized by HLA-A2 restricted cytotoxic T lymphocyte (CTL). METHODS: Utilizing the method of computer prediction followed by a 4h(51)Cr release assay confirmation. RESULTS: The results showed that peripheral blood mononuclear cells (PBMC) obtained from two HLA-A2 positive donors who were infected with HCV could lyse autologous target cells labeled with peptide "ALAHGVRAL (core 150-158)". The rates of specific lysis of the cells from the two donors were 37.5% and 15.8%, respectively. Blocking of the CTL response with anti-CD4 mAb caused no significant decrease of the specific lysis. But blocking of CTL response with anti-CD8 mAb could abolish the lysis. CONCLUSION: The peptide (core 150-158) is the candidate epitope recognized by HLAA2 restricted CTL.
OBJECTIVE: To analyze the molecular karyotypes of ANKA strain of Plasmodium berghei and demonstrate the size and number of chromosomes. METHODS: To isolate the genome DNA of P. berghei ANKA strain and analyze molecular karyotypes through CHEF-III pulsed field gel electrophoresis (PFGE). RESULTS: The number of chromosomes was found to be 14, and their size ranged from 0.6 Mb to 3 Mb. Chromosomes number 5 to 7 and 9 to 12 appeared co-migrated in the gel. CONCLUSION: PFGE technique is useful for analyzing the molecular karyotypes and may be also useful for further study to locate the special gene on chromosomes and carry out the genetic characters and mechanism of drug resistance.
Explore the source record for details and available documents.
Any deregulation of apoptosis or an escape from cellular senescence will drive the cells to neoplasia. It remains unclear whether there is a direct linkage between apoptosis and telomerase activity particularly in transformed cell lines. In the present study, we investigated the telomerase activities in three leukemic cell lines (HL-60, U937 and K562) after treating these cells with various doses of antitumor drugs, puromycin or actinomycin D (ActD). Our results showed that HL-60 cells underwent apoptosis rapidly when treated with either 20 microg/ml of puromycin or 5 microg/ml of Act D with more than 60% of the cells becoming apoptotic at 6 hrs and almost 100% at 12 hrs. But telomerase activity analyzed by TRAP assay in these apoptotic cells remained unchanged as compared with the untreated control cells suggesting that whether the cells were apoptotic or not, it had no effect on telomerase activity. However, if lower dosages of the drugs were used, that is, 0.5-1.5 microg/ml of puromycin or 0.01-0.5 microg/ml of Act D, a decrease in telomerase activity was observed at 24-48 hrs, and was completely undetectable at 72 hrs. This decrease in telomerase activity was dose- and time-dependent. The suppression of telomerase activity by low doses of these two drugs is probably due to the inhibitory effect of the drugs on protein translation or RNA transcription rather than direct inhibition of the telomerase activity. Flow cytometry analysis of the cell cycle of the drug-treated cells showed that these drugs unselectively induced apoptosis at all phases of the cell cycle and was unrelated to the changes in telomerase activity. Similar results were observed in U937 and K562 cells except that K562 cells underwent apoptosis more slowly than the former two cell lines.
BACKGROUND: In this study, we investigated whether dietary intervention could inhibit tumor growth of an androgen-sensitive human prostatic cancer. METHODS: LNCaP cells were transplanted subcutaneously in nude-mice. The animals were then put on different diets and tumor take, tumor growth and prostate specific antigen (PSA) secretion were studied during 9 weeks. RESULTS: Palpable tumors developed in 75% of the tumor-cell injected sites in animals fed a control diet (corn starch, sucrose, etc.) whereas, for animals given rye bran (RB), ethyl acetate extraction from rye bran supplemented cellulose based diets (CCEE), palpable tumors were seen in only 30% and for soy protein based diets (SCC) 50% of the transplantation sites, respectively. The tumors that grew to palpable size in the rye (RB) and soy (SCC) groups were smaller and secreted less PSA than those in the control group. In the rye and soy groups tumor cell apoptosis was increased, but cell proliferation was unaffected. Addition of fat to the rye diet reduced its effect on prostate cancer growth. CONCLUSIONS: Factors in rye bran and soy protein may inhibit prostate cancer growth. The effect is more apparent for rye than for soy. Further studies are needed to identify the effective substances and to explore the mechanism of action.
We report the occurrence of triploid preimplantation embryos following in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) in a woman with two previously-identified triploid conceptuses which spontaneously underwent fetal demise at 10 and 23 weeks' gestation. An error in maternal meiosis II is proposed as the most likely cause.
Endothelins (ET) are important regulators of the hepatic microcirculation that act through different receptor subtypes. We investigated functional significance of ET(B) receptors in mediating microhemodynamic effects of ETs in normal and endotoxin (lipopolysaccharide [LPS])-primed rat liver. LPS priming (Escherichia coli O26:B6; 1 mg. kg(-1)) selectively increased ET(B) mRNA and led to a shift in available receptors to the ET(B) subtype. IRL 1620 (an ET(B) agonist) increased portal pressure in a dose-dependent manner, and the increase in ET(B) expression was associated with prolonged portal pressor response in isolated livers. However, lactate dehydrogenase (LDH) release was attenuated and sinusoidal blood flow was better maintained upon ET(B) stimulation in vivo. In isolated livers, portal constriction as well as release of LDH, were substantially increased in the presence of N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase (NOS). In vivo microscopic assessment of sinusoidal perfusion during ET(B) stimulation revealed a disruption of the flow pattern including frequent reversal of the flow direction without significant sinusoid constriction. Sinusoidal flow decreased even further after discontinuation of IRL 1620. Both effects were mediated at extrasinusoidal sites that probably included postsinusoidal sites. However, after pretreatment with L-NAME, IRL 1620 evoked a significant sinusoidal constriction that colocalized with the body of the stellate cell. We propose that ET(B1)-induced NOS activity attenuates ET(B2) (and presumably ET(A))-mediated portal pressor response and stellate cell constriction. Transcriptional activation of the ET(B) gene may have a permissive effect on liver blood flow and protect against hepatocellular damage under pathophysiological conditions associated with endotoxemia.
Explore the source record for details and available documents.
OBJECTIVES: To determine differences in health status, quality of care, and resource utilization among older diabetic Medicare patients cared for by endocrinologists, internists, family practitioners, and general practitioners. METHODS: The authors analyzed 1,637 patients with diabetes age 65 years or older in the 1994 Medicare Current Beneficiary Survey, a database that links patient surveys to 12 months of Medicare claims data. MEASURES: Measures of morbidity were Basic and Instrumental Activities of Daily Living, health perception, Charlson Comorbidity Index score, and diabetic complications. Quality of care markers were measurement of ophthalmologic visit, lipid testing, glycosylated hemoglobin measurement, mammography, influenza vaccination, early hospital readmission, outpatient follow-up, and patient satisfaction. Resource utilization included reimbursement, relative value units, physician and emergency department visits, and hospitalizations. Age, gender, race, and education were adjusted for in multivariable analyses. RESULTS: Compared with patients of family practitioners, patients of endocrinologists and internists had more comorbidity and diabetic complications but similar health perception and deficiencies in activities of daily living. The patients of endocrinologists also had higher utilization of ophthalmologic screening, lipid testing, and glycosylated hemoglobin measurement than the patients of generalist physicians, but similar rates of influenza vaccination. Patients of endocrinologists and internists had higher total reimbursement than those of family practitioners and general practitioners. Patient satisfaction was generally similar. CONCLUSIONS: Older diabetic patients of endocrinologists had higher utilization of diabetes-specific process of care measures and had similar functional status despite more diabetic complications. However, they received a more costly style of care than patients of family practitioners and general practitioners. Future work needs to explore the optimal coordination of care of diabetic patients among different health providers.
This study was performed to determine whether ischemia/reperfusion (I/R) injury in rat liver results in alterations in endothelin receptor expression. Hepatic ischemia was produced in rats for 60 min followed by 6 or 24 h reperfusion. Portal inflow pressure was increased (7.38+/-0.60 mmHg) at 24 hours after reperfusion. Serum ALT increased significantly at both 6 and 24 h (6 h; 258.3+/-74.3, 24 h; 243.1+/-74.8 IU/L). Portal vascular response to an endothelin-B receptor agonist (IRL 1620) was significantly increased in the I/R livers compared to control and this was potentiated by L-NAME. IRL 1620 also caused LDH release from I/R livers but not controls. LDH release after IRL 1620 in I/R livers correlated with increased portal pressure response. To determine whether the altered response might be the result of altered endothelin receptor expression, livers were harvested after reperfusion and total endothelin binding sites were determined by competitive binding with ET-1. Proportion of endothelin receptor subtypes (ET(A)/ET(B)) was determined using the ET(A) antagonist BQ-610 (1 microM) and ET(B) agonist IRL-1620 (100 nM). There were no significant changes in Kd but Bmax for endothelin-1 was decreased in I/R group especially non-ischemic lobe at 24 h. ET(A) receptors were significantly decreased whereas ET(B) receptors were increased. These changes were more pronounced at 24 h after reperfusion than at 6 h. Interestingly, the changes in ET receptors was observed identically both in ischemic and non-ischemic lobes (ischemic lobe ET(A) 41.9%, ET(B) 51%; non-ischemic lobe ET(A) 38.8%, ET(B) 49.5%). These results indicate that the major functional endothelin receptor subtype upregulated in I/R is the ET(B) receptor and that this upregulation may contribute to microvascular dysregulation and hepatic injury.
Explore the source record for details and available documents.
Objective. To investigate the effects of different training methods on cardiovascular autonomic regulation under bedrest. Method. 15 healthy male volunteers aged 19-22 participated tests in head-down tilt (HDT) -6 degrees bedrest in order to observe the changes of cardiovascular system under simulated weightlessness. They were divided into control (5 men), hypoxia training (5 men) and Fangsong training (5 men) groups. 24 h dynamic ECG were recorded on the 2nd day of pre-bedrest, on the 3rd, 14th and 18th day of bedrest and on the 7th day of the post- bedrest. All spectra were estimated from entire 24 h HRV, before, during and after Fangsong and hypoxia training by autoregressive (AR) modeling method. Normalized low-frequency (LF%) was a quantitative marker of cardiac sympathetic activity, normalized high-frequency (HF%) reflected the changes in cardiac vagal activity, and LF/HF was considered to be related to sympathovagal balance or sympathetic activity. Result. In control group, LF% and HF% were all significantly reduced (P<0.05), LF/HL showed no significant changed during bedrest. In Fangsong group, HF% increased markedly (P< 0.05), while in hypoxia group, LF% increased markedly (P< 0.05). Conclusion. Fangsong training counteracted markedly the reduction in vagal activity, while hypoxia training counteracted markedly the decrease in sympathetic activity. It was possible that HRV indices could be used to evaluate the efficiency of countermeasures counteracting the adverse effects of weightlessness.
OBJECTIVE: To establish methodologically a method for quantitative determination of beta-eudesmol in Atractylodes lancea. METHOD: GC, column: 3 mm x 2 m; stationary phase; 15% QF-1; support: Chromosorb WAW(60-80 mesh); detector: hydrogen flame ionization detector; injection chamber temperature: 210 degrees C; column temperature: 174 degrees C; carrier gas: N2:50 ml.min-1, air: 49 kPa, H2:58.8 kPa; sensibility range: 10(2) x 64; chart speed: 2.5 mm.min-1. RESULT: Average recovery ratio is 100.7% (n = 5). CONCLUSION: This method can be used to control the quality of A. lancea.
Tricarboxylic acid (TCA) cycle is an important way to generate ATP, which is widely distributed in the cells of animal, plant or microorganism. It catalyses the catabolism of sugar as well as protein and fat. Citrate synthase plays a key role in regulating TCA cycle and is responsible for catalysing the synthesis of citrate from oxaloacetate and acetyl CoA. Screening of genomic informatics was performed by using pig citrate synthase cDNA as a probe and a contig which is 1636 bp long and has highly homologous to the pig citrate synthase cDNA was obtained from selected ESTs with the ASSEMBLY program. According to the sequence of this contig, a pair of primers was designed and used to amplify cDNA libraries. A 1492 bp cDNA containing an open reading frame encoding 466 amino acids was cloned from human testis and skeletal muscle cDNA libraries. The deduced amino acid sequence of the cDNA showed 95%, 92% and 60.9% identity to pig, chicken and yeast citrate synthase respectively. Because the deduced amino acids sequence contains a highly conserved motif of citrate synthase from three different species, it is believed that this cDNA may be a transcript of human citrate synthase gene. Northern analysis showed that the human citrate synthase was expressed at high level in heart and muscle, at middle level in brain, kidney and pancreas tissues, not detectable in thymus and small intestine tissues, and at low level in other nine tested human tissues.