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Biomedical subjects

S Tang

Publications and source records attributed to S Tang.

At least 127 records · Page 7Linked to original sources
PubMed1999

Synergistic effects of cAMP- and calcium-mediated amylase secretion in isolated pancreatic acini from cystic fibrosis mice.

We evaluated pancreatic enzyme secretory response to secretagogues (cAMP- and Ca2+-mediating) involved in exocytosis and in chloride channel activation in an exon 10 knockout cystic fibrosis (CF) mouse model. Experiments were performed in isolated pancreatic acini from liquid-fed Cftr-/- mice (5-6 wk of age) and age-matched Cftr+/+ controls fed a solid or liquid diet. BrcAMP and forskolin alone induced higher amylase secretion (% initial amylase content) in the Cftr+/+ acini than carbachol (p < 0.05). Carbachol and BrcAMP or BrcAMP and forskolin, given in combination, produced additive effects on enzyme secretion in the Cftr+/+ acini. Ca2+- and cAMP-mediated amylase secretion in isolated pancreatic acini from the Cftr-/- mice was no different to that observed in the age- and diet-matched Cftr+/+ animals. However, Cftr-/- pancreatic acini showed a significantly greater amylase response to the combination of BrcAMP and carbachol than the sum of the individual responses in separate experiments (p < 0.05). The amylase response was not different in acini from solid-fed or liquid-fed Cftr+/+ controls. In summary, this study suggests that cystic fibrosis transmembrane conductance regulator is not essential for enzyme secretion as evidenced by no reduction in cAMP-mediated amylase secretion in Cftr-/- mice. The results in Cftr+/+ acini suggest pancreatic enzyme secretion is mediated via multiple intracellular pathways acting in parallel and probably converge at a distal step in the secretory process. However, Cftr-/- pancreatic acini exhibited a synergistic secretory response following stimulation by BrcAMP plus carbachol. The enhanced secretory response may partially contribute to the development of pancreatic dysfunction in CF patients by facilitating occlusion of digestive enzymes in the secretory canaliculus of the pancreatic acini.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1999

Apical proteins stimulate complement synthesis by cultured human proximal tubular epithelial cells.

There is increasing evidence to suggest that the renal tubular epithelium is important in the pathogenesis of progressive renal failure resulting from persistent proteinuria. The role of complement in the progression of chronic renal failure is not well defined. The purpose of this study was to characterize the production of complement by human proximal tubular epithelial cells exposed to serum proteins at the apical surface. Complement C3 gene expression was analyzed by reverse transcription and PCR. C3 protein biosynthesis was confirmed by metabolic labeling followed by immunoprecipitation and quantified by enzyme-linked immunosorbent assay. In the quiescent state, proximal tubular epithelial cells grown on permeable membrane supports secreted C3 predominantly into the apical medium. The addition of 5 mg/ml serum proteins led to an 8.9-fold increase in basolateral C3 secretion and a 2.1-fold increase in apical C3 secretion, altering the ratio of basolateral: apical C3 secretion from 0.44 +/- 0.16 to 1.87 +/- 0.52. C3 mRNA expression was also upregulated in a time- and dose-dependent manner. Serum fractionation demonstrated that the stimulant responsible for these effects was in the molecular weight range 30 to 100 kD. The observed phenomenon was not reproduced when purified human albumin alone was used as the stimulant. These findings could provide a possible mechanism for the link between proteinuria and interstitial fibrosis. This may have potential implications for strategies directed against complement in retarding the progression of chronic renal failure.

Cells, Cultured↗
PubMed1999

Long-term renal allograft recipients from South-east Asia in the pre-cyclosporin era.

The clinical outcome of long-term renal allograft recipients in the Chinese population has not been reported previously. We analysed patients from the pre-cyclosporin era who had grafts that functioned for > 10 years. Forty-five patients (31 men, 14 women; mean age 30, follow-up duration 13.3 years), representing a 10-year graft survival of 53%, were included. Thirty-six patients (80%) received living-related allografts and 9 (20%) received cadaveric or living-unrelated renal transplantation. The mean serum creatinine at last follow-up was 1.36 mg/dl (range, 0.83-4.08). Major posttransplantation complications included: hypertension in 25 (56%), infection in 16 (36%), acute rejection in 15 (33%), lipid disorder in 13 (29%), liver disease in 7 (16%), osteonecrosis in 5 (11%), malignancy in 4 (9%), coronary artery disease in 3 (7%), and diabetes mellitus in 3 (7%). Five grafts were lost: 3 to chronic rejection, and 2 to patients with stable function who died of non-renal causes. Proteinuria correlated strongly with graft function and survival, and marginally with hypertension. In hepatitis B carriers, serum alpha-feto protein is useful in the early detection of hepatocellular carcinoma. We conclude that while patients in the pre-cyclosporin era can survive with excellent graft function beyond the first decade, the risk of complications leading to significant morbidity still remains even when patients are receiving minimal doses of immunosuppression in the second decade.

Adolescent↗
PubMed1999

An experimental investigation of osseointegration and stability of implants used as orthodontic anchorage in dogs.

OBJECTIVE: To investigate osseointegration and stability of three kinds of implants used as orthodontic anchorage in dogs. METHODS: HA-coated, titanium plasma-coated, and uncoated titanium implants were inserted into each femur of two dogs. After a healing period of three months, orthodontic force of 200 g was applied by means of Ni-Ti springs which were connected to the two adjacent implants for two months. Position change of the implant was first measured and then calculated. The shear bond strength of the interface between implant and bone was measured with a push test. After the test, the fracture surface at the interface was observed with a scanning electronic microscope. RESULTS: All implants were stable, without mobility. The highest bond strength and mature bone compactness were found at the interface between HA-coated implant and bone. The other two showed no significant difference in bond strength. However, osseointegration existed at the interface between all three kinds of implants and bone. CONCLUSION: HA-coated, titanium plasma-coated, and uncoated titanium implants can each serve as orthodontic anchorage as well as prosthodontic abutment.

Animals↗
PubMed1999

[The study on the role of apoptosis suppressive gene bcl-2 in the pathogenesis of hemangioma].

OBJECTIVE: To elucidate the relationship between bcl-2 and hemangioma. METHODS: We investigated the expression of bcl-2 in 38 samples of hemangioma (19 cases of capillary hemangioma, 10 cases of cavernous hemangioma, 9 cases of racemose hemangioma) and 6 samples of normal skin by immunohistochemical SP method. RESULTS: The results showed that the expression of bcl-2 was higher in cavernous and racemose hemangioma than in the controls, the expression of bcl-2 was lower in capillary hemangioma than in the controls. The differences were statistically significant. CONCLUSION: It can be deduced from the results that there is an intimate relationship between bcl-2 and the growth of cavernous and racemose hemangioma, and the lower expression of bcl-2 in capillary hemangioma shows that capillary hemangioma may disappear naturally.

Adolescent↗
PubMed1999

[Changes in TGF-beta 1 and type I, III procollagen gene expression in keloid and hypertrophic scar].

OBJECTIVE: The expression of mRNA for TGF-beta 1, type I, III procollagen in keloid and hypertrophic scar was investigated in order to elucidate the pathogenesis of and the difference between keloid and hypertrophic scar. METHOD: Dot-blot hybridization analysis was used to examine the type I, III procollagen and the expression levels of steady-state mRNA. In situ hybridization allowed direct assessment of the distribution of TGF-beta 1 mRNA in the tissue. RESULTS: 1. Our study indicated that the expression level of mRNA for TGF-beta 1 significantly increased in keloid and hypertrophic scar compared with normal scar and normal skin. 2. In keloid tissues, type I precollagen mRNA expression was selectively increased. However, in hypertrophic scar, type I and III collagen mRNAs expressions were simultaneously increased. CONCLUSION: TGF-beta 1 plays an important role in the pathogenesis of keloid and hypertrophic scarring. It implicates that distinct molecular mechanisms are operative in the development of keloid and hypertrophic scarring.

Cicatrix, Hypertrophic↗
PubMed1999

[Signal of the cytoplasmic regions of leukemia inhibitory factor receptor (LIFR) alpha-subunit and gp130 involves Stat3 activation in leukemic U937 cells].

OBJECTIVE: In order to understand the mechanism of proliferation and differentiation of leukemia cells, we investigate the relation between the cytoplasmic regions LIFR alpha-subunit and gp130 and the transcription activator Stat3 in human leukemic U937 cells. METHODS: The cytoplasmic domain was each truncated from the LIFR alpha-subunit and gp130. The truncated forms of LIFR alpha-subunit(gp190EX) and gp130 (gp130EX) which can compete with the wild type receptor for binding to leukemia inhibitory factor (LIF) were expressed on the membrane of U937 cells. The level of Stat 3 and its phosphorylation were estimated by immunoblotting. RESULTS: The increased level of Stat3 and its decreased tyrosine phosphorylation were detected in each group of gp130EX and gp190EX as compared with that in the wild type receptor subunit group. CONCLUSION: The cytoplasmic domains of both LIFR alpha subunit and gp130 involve the induction of Stat3 phosphorylation in U937 cells.

Antigens, CD↗
PubMed1999

[Influence of intravenous-immunoglobulin on T lymphocyte subsets, NK cell and some cytokines in mice with experimental viral myocarditis].

This study sought to gain an insight into the immunological pathogenesis of viral myocarditis and the mechanism of therapeutic action of intravenous-immunoglobulin (IVIG) on the disease, BALB/c mice were randomized into four groups: normal control group; "myocarditis model group", inoculated intraperitoneally with CVB3; "IVIG protection group", injected intraperitoneally with CVB3 and IVIG; and "IVIG treatment groups", injected intraperitoneally with CVB3 and IVIG. The amount of T cell in different T cell subsets and the activities of NK cell, IL-1 and IL-2 were assayed using spleen specimen while peripheral blood was used to measure TNF activity. The results showed: that in comparison with normal control, all spleen T cell subsets decreased in amount in myocarditis model group, so did its NK cell activity while its IL-1, IL-2 and TNF activities increased significantly. When compared with myocarditis model group, however, both IVIG protection group and IVIG treatment group showed significant elevation of NK cell activity and T cell subsets but reduced IL-1, IL-2 and TNF activities with no remarkable change in T cell subsets. The results of suggest that the immunological injury mediated by T cells plays a critical role in the pathogenesis of viral myocarditis. The protective and therapeutic effects of IVIG on the murine CVB3 myocarditis and the related immunological evidence of its actions may indicate the prospect that IVIG will become a potent and safe treatment for viral myocarditis in human.

Animals↗
PubMed1999

[Study on heparin-like materials--sulfonization and blood compatibility of PVA, PET and PEU].

In this paper, physical mechanical properties and changes of chemical structures of some heparin-like biomaterials were studied before and after sulfonization of PVA, PET and PEU. The results showed that these materials were easy to be sulfonized, but it was necessary to keep actual sulfonization degree for their mechanical properties. Platelets adhesion experiments demonstrated that the materials adsorbed very few and showed heparin-like anti-coagulant property after sulfonization.

Animals↗
PubMed1999

[Activated T lymphocytes in epiretinal membranes from eyes of patients with proliferative diabetic retinopathy].

PURPOSE: To investigate the potential contribution of immune-mediated processes to the development of proliferative diabetic retinopathy(PDR), an immunohistochemical study was undertaken to characterize the infiltrating immune cells in epiretinal membrances from the eyes of patients with PDR. METHODS: A total of 15 PDR epiretinal membrane specimens obtained surgically from pars plans vitrectomy were studied by using a panel of monoclonal antibodies against T lymphocytes (CD4), interleukin-2(IL-2) and interleukin-2 recpetors(IL-2R). RESULTS: Twelve of 15 specimens (80%) contained CD4-positive cells. IL-2 was found in 12 of 15 samples (80%), of which 11 also contained CD4-positive cells, and IL-2R was detected in 10 of 15 membranes(67%), of which 9 contained CD4-positive cells and released IL-2. Most of the IL-2R-positive membranes were from type I diabetic patients, 40% of them are younger than 40 years. CONCLUSION: Our study demonstrated the involvement of activated immune cells and release of lymphokine(s) in more than half of the diabetic epiretinal membranes tested and revealed that the processes of immune responses and the biological effects of lymphokines(s) may play an important part in the development of epiretinal membranes of PDR, especially in young-onset and type I diabetes.

CD4 Antigens↗
PubMed1999

[New solution of simultaneous equations in spectrophotometry for the determination of aspirin and acetaminophen in xiaoer tuishao pian].

The contents of aspirin and acetaminophen in xiaoer tuishao pian were determined by using the new solution of simultaneous equations without any preliminary separation. The average recoveries and variation coefficients of the analysis are 99.95% and 1.74% for aspirin and 100.1% and 0.93% for acetaminophen, respectively. The method was simple, rapid and accurate.

Acetaminophen↗
PubMed1998

Leptin indirectly affects estrous cycles by increasing metabolic fuel oxidation.

In previous experiments, lean Syrian hamsters fasted on days 1 and 2 of the estrous cycle failed to show sex behavior and ovulation normally expected to occur on the evening of day 4. The first goal of the present experiment was to determine whether systemic treatment with the ob (obese) protein leptin could reverse the effects of fasting on estrous cyclicity, social behaviors, and ovulation rate. Fasting-induced anestrus was reversed and normal sex and social behavior and ovulation rate were restored in hamsters injected intraperitoneally with 5 mg/kg leptin every 12 h during fasting on days 1 and 2 of the estrous cycle. A second goal was to test whether the effects of leptin could be prevented by treatment with pharmacological agents that block the oxidation of metabolic fuels. Glucose oxidation was blocked by treatment with 2-deoxy-d-glucose (2DG) and fatty acid oxidation was blocked by treatment with methyl palmoxirate (MP). 2DG (1000 mg/kg) or MP (20 mg/kg) was administered at doses that did not induce anestrus in hamsters fed ad libitum. As in the first experiment, fasting-induced anestrus was reversed by leptin treatment. However, when each injection of leptin was preceded by an injection of 2DG or MP, leptin treatment did not reverse fasting-induced anestrus. In summary, estrous cyclicity was not restored when oxidation of metabolic fuels was blocked, despite high endogenous levels of leptin. These results are consistent with the hypothesis that leptin acts indirectly on the reproductive system by increasing fuel oxidation.

Aggression↗
PubMed1998

Stimulation of 125I-transferrin binding and 59Fe uptake in rat adipocytes by vanadate: treatment time determines apparent tissue sensitivity.

Vanadium compounds have been documented to stimulate a number of insulin biological effects in vitro and in vivo. We previously demonstrated stimulation of glucose transport and insulin-like growth factor-II (IGF-II) binding in rat adipocytes. These actions are associated with translocation of glucose transporters and IGF-II receptors from an intracellular compartment to the plasma membrane. The transferrin receptor is also recruited to the plasma membrane in response to insulin. Freshly isolated rat adipocytes were incubated with vanadate and insulin at 37 degrees C, and after treating the cells with KCN to inhibit further receptor movement, diferric 125I-transferrin binding was assayed. Vanadate stimulated a dose- and time-dependent increase in 125I-transferrin binding, reaching maximum (approximately threefold) stimulation at 1 mmol/L after a 4-hour incubation. This was equivalent to the maximum insulin effect that was obtained with 10(-8) mol/L after 30 minutes. A similar degree of stimulation was achieved with 0.1 mmol/L vanadate after 8 hours of exposure. Dose-response data showed that the apparent sensitivity to vanadate was time-dependent and increased with the duration of exposure (EC50: 30 minutes, 1 mmol/L; 3 hours, 0.35 mmol/L). Scatchard analysis of 125I-transferrin binding showed that both insulin and vanadate increased receptor binding capacity with no effect on receptor affinity. Total cellular transferrin receptor content measured by immunoblotting with monoclonal anti-transferrin receptor antibody (OX-26) was not altered by insulin or vanadate, consistent with receptor translocation. Assessment of 59Fe uptake from 59Fe-labeled diferric transferrin showed that vanadate augmented 59Fe uptake in a dose-dependent manner to an extent similar to insulin, demonstrating the functional activity of the receptors (percent of control: 10(-8) mol/L insulin, 175% +/- 23.8%, P < .02; 0.3 mmol/L vanadate, 188% +/- 17.3%, P < .01). We conclude that vanadate mimics insulin to augment cell surface transferrin receptors and increase Fe uptake in rat adipocytes. The time-dependent apparent increase in sensitivity is consistent with the effectiveness of very low concentrations of vanadate in vivo after several days of administration, and suggests a requirement for vanadate entry into cells to mediate this biological response.

Adipocytes↗
PubMed1998

Benefits of exercise training in patients on continuous ambulatory peritoneal dialysis.

We examined the effects of a 12-week exercise program on the exercise tolerance, blood biochemistry, blood pressure (BP) control, cardiac function, and quality-of-life (QOL) scores in 13 patients undergoing continuous ambulatory peritoneal dialysis (CAPD; six men, seven women; mean age, 46.5+/-12.8 years; mean duration on dialysis, 4.8+/-3.8 years). The patients underwent exercise training on treadmill, bike, and arm ergometers thrice weekly. Seven CAPD patients matched for age, sex, and duration on dialysis served as controls. The mean peak aerobic capacity (VO2peak) of the exercisers increased by 16.2% after training (pre- and postexercise, 17.2+/-5.2 v 20.0+/-6.4 mL/kg/min; P=0.004). Although there were no significant changes in serum urea, creatinine, albumin, and hematocrit levels; left ventricular diastolic/systolic diameters; and ejection fraction, an increasing trend of high-density lipoproteins (HDLs) was observed in the exercisers (baseline v postexercise, 33+/-11 v 40+/-14 mg/dL; P=0.06). Twenty-four-hour ambulatory BP monitoring showed a significant increase in daytime systolic BP in the exercisers (pre- and postexercise, 142+/-26 v 157+/-22 mm Hg; P=0.003), but no significant changes could be found in the ambulatory daytime diastolic BP, nocturnal BP, and resting clinic BP. The patients' QOL improved after training, with better scores in two Kidney Disease Quality of Life scales (KDQOL): burden of kidney disease and physical functioning. Two mild and uncomplicated hypotensive episodes were reported in two patients immediately after training. No changes occurred in exercise capacity, blood biochemistry, BP profile, and QOL scores in the controls. We conclude that structured aerobic exercise is safe and can improve the exercise tolerance and QOL outcomes in CAPD patients.

Adult↗
PubMed1998

Translation efficiencies of the 5' untranslated region from representatives of the six major genotypes of hepatitis C virus using a novel bicistronic reporter assay system.

The 5' untranslated region (5'UTR) of hepatitis C virus (HCV) contains an internal ribosome entry site (IRES) which directs translation of the viral open reading frame (ORF). The 5'UTR is highly conserved between virus isolates in both primary sequence and predicted secondary structure. We cloned and sequenced the 5' regions (nt 18 of the 5'UTR to nt 15 of the core coding sequence) of HCV isolates representing the six major genotypes and subcloned these into a bicistronic, dual luciferase reporter construct. The relative expression of the two luciferases, one directed by the HCV IRES and the other by cap-dependent ribosome scanning, was used to compare the activities of the different IRES elements in transfected cells. The 5'UTR from a genotype 2b isolate was the most efficient at directing translation in all four cell lines tested: BHK-21, HeLa-T4+, HuH7 and HepG2. In HepG2 cells the 2b 5'UTR was three times as efficient as the type 6a 5'UTR, which was generally the least active IRES tested. These data suggest that HCV isolates are not able to translate their ORF with equal efficiency, and provide a starting point from which further sequence-function studies can be undertaken.

5' Untranslated Regions↗