Biomedical subjects

C Yang

Publications and source records attributed to C Yang.

At least 73 records · Page 4Linked to original sources

PubMed2001

VAMP3 null mice display normal constitutive, insulin- and exercise-regulated vesicle trafficking.

To investigate the physiological function of the VAMP3 vesicle SNARE (v-SNARE) isoform in the regulation of GLUT4 vesicle trafficking, we generated homozygotic VAMP3 null mice by targeted gene disruption. The VAMP3 null mice had typical growth rate and weight gain, with normal maintenance of fasting serum glucose and insulin levels. Analysis of glucose disposal and insulin sensitivity demonstrated normal insulin and glucose tolerance, with no evidence for insulin resistance. Insulin stimulation of glucose uptake in isolated primary adipocytes was essentially the same for the wild-type and VAMP3 null mice. Similarly, insulin-, hypoxia-, and exercise-stimulated glucose uptake in isolated skeletal muscle did not differ significantly. In addition, other general membrane trafficking events including phagocytosis, pinocytosis, and transferrin receptor recycling were also found to be unaffected in the VAMP3 null mice. Taken together, these data demonstrate that VAMP3 function is not necessary for either regulated GLUT4 translocation or general constitutive membrane recycling.

Adipocytes↗

PubMed2001

Syntaxin 4 heterozygous knockout mice develop muscle insulin resistance.

To investigate the physiological function of syntaxin 4 in the regulation of GLUT4 vesicle trafficking, we used homologous recombination to generate syntaxin 4-knockout mice. Homozygotic disruption of the syntaxin 4 gene results in early embryonic lethality, whereas heterozygous knockout mice, Syn4(+/-), had normal viability with no significant impairment in growth, development, or reproduction. However, the Syn4(+/-) mice manifested impaired glucose tolerance with a 50% reduction in whole-body glucose uptake. This defect was attributed to a 50% reduction in skeletal muscle glucose transport determined by 2-deoxyglucose uptake during hyperinsulinemic-euglycemic clamp procedures. In parallel, insulin-stimulated GLUT4 translocation in skeletal muscle was also significantly reduced in these mice. In contrast, Syn4(+/-) mice displayed normal insulin-stimulated glucose uptake and metabolism in adipose tissue and liver. Together, these data demonstrate that syntaxin 4 plays a critical physiological role in insulin-stimulated glucose uptake in skeletal muscle. Furthermore, reduction in syntaxin 4 protein levels in this tissue can account for the impairment in whole-body insulin-stimulated glucose metabolism in this animal model.

Adipocytes↗

PubMed2001

The MEF2A and MEF2D isoforms are differentially regulated in muscle and adipose tissue during states of insulin deficiency.

Previously we have demonstrated that striated muscle GLUT4 gene expression decreased following streptozotocin-induced diabetes due to a loss of MEF2A transcription factor expression without any significant effect on the MEF2D isoform (Mora, S. and J. E. Pessin (2000) J Biol Chem, 275:16323-16328). In contrast to both cardiac and skeletal muscle, adipose tissue displays a selective decrease in MEF2D expression in diabetes without any significant alteration in MEF2A protein content. Adipose tissue also expresses very low levels of the MEF2 transcription factors and nuclear extracts from white adipose tissue exhibit poor in vitro binding to the MEF2 element. However, addition of in vitro synthesized MEF2A to adipose nuclear extracts results in the formation of the expected MEF2/DNA complex. More importantly, binding to the MEF2 element was also compromised in the diabetic condition. Furthermore, in vivo overexpression of MEF2A selectively in adipose tissue did not affect GLUT4 or MEF2D expression and was not sufficient to prevent GLUT4 down-regulation that occurred in insulin-deficient states.

Adipose Tissue↗

PubMed2001

Prodrugs in nasal drug delivery.

Prodrugs have been used to overcome poor solubility, insufficient stability, incomplete absorption across biological membranes and premature metabolism to active species. This review examines the importance of various physicochemical factors affecting nasal absorption of drugs. Novel trends in nasal prodrug development in the areas of targeted delivery to the CNS and selective targeting of the nutrient transporter system of the nasal mucosa have received considerable attention.

Administration, Intranasal↗

PubMed2001

Prodrug based optimal drug delivery via membrane transporter/receptor.

The carrier-mediated absorption of drugs and prodrugs across epithelial and endothelial barriers is emerging as a novel trend in biotherapeutics. This review examines the important advances in this field in the past decade. The feasibility of drug absorption of the parent drug or the appropriately modified prodrug via these transporters is discussed in detail. Several successful examples of synthesis of prodrugs recognised by the targeted transporters are described. The applicability of this approach in translocating drugs across the almost impenetrable blood-brain barrier (BBB) has also been examined.

Adsorption↗

PubMed2001

Adaptation of a strain of Plasmodium vivax from India to New World monkeys, chimpanzees, and anopheline mosquitoes.

A strain of Plasmodium vivax from India was adapted to develop in splenectomized Saimiri boliviensis, Aotus lemurinus griseimembra, A vociferans, A. nancymai, A. azarae boliviensis, hybrid Aotus monkeys, and splenectomized chimpanzees. Infections were induced via the inoculation of sporozoites dissected from the salivary glands of Anopheles stephensi and An. dirus mosquitoes to 12 Aotus and 8 Saimiri monkeys; transmission via the bites of infected An. stephensi was made to 1 Aotus monkey and 1 chimpanzee. The intravenous passage of infected erythrocytes was made to 9 Aotus monkeys and 4 chimpanzees. Gametocytes in 13 Aotus monkeys and 4 chimpanzees were infectious to mosquitoes. Infection rates were markedly higher in mosquitoes fed on chimpanzees. PCR studies on 10 monkeys injected with sporozoites revealed the presence of parasites before their detection by microscopic examination. The India VII strain of P. vivax develops in Aotus and Saimiri monkeys and chimpanzees following the injection of parasitized erythrocytes, or sporozoites, or both. The transmission rate via sporozoites to New World monkeys of approximately 50% may be too low for the testing of sporozoite vaccines or drugs directed against the exoerythrocytic stages. However, the strain is highly infectious to commonly available laboratory-maintained anopheline mosquitoes. Mosquito infection is especially high when feedings are made with gametocytes from splenectomized chimpanzees.

Adaptation, Biological↗

PubMed2001

Rosiglitazone (BRL 49653) enhances insulin secretory response via phosphatidylinositol 3-kinase pathway.

To elucidate the direct effect of rosiglitazone (RSG), a new thiazolidinedione antihyperglycemic agent, on pancreatic insulin secretion, an in situ investigation by rat pancreatic perfusion was performed. At a basal glucose concentration of 6 mmol/l, RSG (0.045-4.5 micromol/l) stimulated insulin release in a dose-dependent manner. In addition, 4.5 micromol/l RSG potentiated the glucose (10 mmol/l)-induced insulin secretion. Both the first and second phases of glucose-induced insulin secretion were significantly enhanced by RSG, by 80.7 and 52.4%, respectively. The effects of RSG on insulin secretion were inhibited by a phosphatidylinositol 3-kinase (PI3K) inhibitor, LY294002. In contrast, the glucose-stimulated insulin secretion was not affected by LY294002. The potentiation effect of RSG on glucose-stimulated insulin secretion, in both the first and second phases, was significantly blocked by LY294002. These results suggest that RSG has a direct potentiation effect on insulin secretion in the presence of 10 mmol/l glucose, mediated through PI3K activity. The inability of LY294002 to inhibit glucose-induced insulin secretion suggests that different pathways are responsible for glucose and RSG signaling.

Animals↗

PubMed2001

[A study of Wilson's disease gene encoded products and gene mutations].

OBJECTIVE: To investigate the pathogenesis of Wilson's disease(WD). METHODS: Hepatocytes were isolated from WD patients' bioptic hepatic samples and cultured in vitro; WD proteins, the gene putative encoded products, were detected by SDS-PAGE in conjunction with Western blotting in liver samples of three patients and two controls. Their genomic DNAs were analyzed by means of direct DNA sequencing of WD gene (ATP7B) on exon 8. RESULTS: The WD proteins lanes from two WD patients were found to be much weaker than that from the control, from which one WD patient was proven as heterozygote of 778 position CGG-->CTG(Arg778Leu) and 770 position CTC-->CTG change of ATP7B. CONCLUSION: WD is highly heterogeneous in clinical manifestations and inheritance pattern. Abnormally expressed putative WD proteins in WD patients might be the results of ATP7B mutations, and the study of ATP7B products would help to probe into the pathogenesis of WD.

Adenosine Triphosphatases↗

PubMed2001

[The development of multi-lead EEG telemetry and tele-monitoring system].

This paper introduces a kind of EEG Telemetry and Tele-monitoring system. With the use of the public telephone network to transport signals and the portable EEG recording system as the sender of system, the EEG data of 20 standard leads can be transmitted to the receiver of system (monitoring center) synchronously. And at the monitoring center, the waves can be displayed real-time, freezing, stored, reviewed, analyzed and printed, thus providing aid in remote diagnosis and treatment consultations.

Computer Communication Networks↗

PubMed2001

[Factors related to post-treatment marital adjustment in women with breast cancer].

The purpose of this study was to explore post-treatment marital adjustment and related factors in women with breast cancer. The variables include characteristics of illness, pre- and post-treatment marital adjustment, as well as depression. Subjects were recruited by convenience sampling from two medical centers and one community hospital in the Taipei metropolitan area. A total of 119 married women who had received surgery for breast cancer were interviewed with structured questionnaires in a private space. The results showed no difference between marital adjustment pre- and post-treatment. A significant decrease in physical aspects of marriage satisfaction and a significant increase in both psychological and social aspects of marriage satisfaction post-treatment were demonstrated. However, stepwise regression analyses found that the most important predictor of post-treatment marital adjustment is pre-treatment adjustment. Such variables as post-morbid duration, stage of cancer, and different treatment modalities could also predict post-treatment marital adjustment. The results suggest that medical staff should encourage breast cancer patients to face their post-treatment marital status positively. The impact on physical aspects of marriage satisfaction of the breast cancer treatment should not be overlooked. Moreover, an assessment of ovarian function, sexual function, depression, and marital adjustment should be emphasized in women with breast cancer.

Adaptation, Psychological↗

PubMed2001

[Intratumoral injection of macroaggragated albumin and colloidal 32P for the treatment of hepatocellular carcinoma].

OBJECTIVE: To study the tumor deposition and systemic distribution of colloidal (32)P in single colloidal (32)P injection and macroaggragated albumin (MAA) injection followed by colloidal (32)P and to evaluate their clinical effects and side effects for the treatment of hepatocellular carcinoma. METHODS: H(22) hepatocellular cancer cells were inoculated subcutaneously in the right fore leg of Balb/c mice. When the tumors reached to 1.0 cm in diameter about 10 days postinjection, the mice were divided into two groups randomly. In the first group, the tumors were only injected with 1.85 MBq of colloidal (32)P; while in the second group, with 1 +/- 10(5) particles of MAA followed by 1.85 MBq of colloidal (32)P. The radioactivity in the tumor, blood, heart, liver, kidney, spleen, and bone of each animal was determined at 30min, 24 h, 48 h, 8 d, and 16 d postinjection. Histopathology of tumors was observed at 16 d and 1 month postinjection. The ultrasound-guided intratumoral injection of MAA and colloidal (32)P was performed on 30 patients with hepatocellular cancer. The evaluation of efficacy and side effects was made on the basis of clinical manifestations, histopathological changes, variations in tumor size, serum AFP, the functions of heart, liver, kidney, blood routine, and immune functions before and after the treatment. RESULTS: Intratumoral injection of colloidal (32)P resulted in necrosis and fibrosis of the tumor cells. Pretreatment with MAA before administration of colloidal (32)P effectively decreased the diffusion of colloidal (32)P from the tumor to blood, and led to retention of colloidal (32)P in the tumor for a longer time. After treatment, a significant shrinkage of the tumor size was seen in all cases with the average shrinkage rate of 53.25%. Serum AFP values decreased remarkably. Clinical symptoms alleviated. The survival rate of 1, 2, and 3 years was 90%, 76.67%, 43.33%. No side effect was found. CONCLUSIONS: Intratumoral injection of MAA and colloidal (32)P is a simple, safe, and effective alternative for the treatment of hepatocellular cancer.

Adult↗

PubMed2001

Eudesmanolides, aromatic derivatives, and other constituents from Carpesium cernuum.

A new eudesmanolide 13-hydroxy-4 alpha H-eudesman-5,7(11)-dien-12,8 beta-olide (1) and a new aromatic derivative 3-methyl-8-acetoxy-9,10-diisobutanoyloxy-p-cymene (6), along with ten known compounds were isolated from the roots of Carpesium cernuum L. Their structures were elucidated by spectral methods (IR, EIMS, FAB-MS, 1D and 2D NMR). Compound 2, 3 and compound 10 exhibited moderate antibacterial activity against Bacillus subtilis, Escherichia coli and Staphylococcus aureus.

Anti-Bacterial Agents↗

PubMed2001

Selective oxidation in vitro by myeloperoxidase of the N-terminal amine in apolipoprotein B-100.

In contrast to the multiple low abundance 2,4-dinitrophenylhydrazine-reactive tryptic peptides formed by oxidation of LDL with reagent HOCl in vitro, myeloperoxidase-catalyzed oxidation produces a dominant product in considerably greater yield and selectivity. This modified peptide had a single amino-terminal sequence corresponding to amino acids 53-66 of apolipoprotein B-100 (apoB-100), but its mass spectra indicated a significantly higher mass than could be reconciled with simple modifications of this peptide. Subsequent studies indicate that this product appears to result from N-chlorination of the N-terminal amino group of apoB-100 and dehydrohalogenation to the corresponding imine, which may form the hydrazone derivative directly, or after hydrolysis to the ketone. The methionine residue is oxidized to the corresponding sulfoxide, and the primary sequence peptide (residues 1-14 of apoB-100) is linked by the intramolecular disulfide bond between C-12 and C-61 to the peptide composed of residues 53-66, as we have observed previously (Yang, C-Y., T. W. Kim, S. A. Weng, B. Lee, M. Yang, and A. M. Gotto, Jr. 1990. Proc. Natl. Acad. Sci. USA. 87: 5523-5527) in unmodified LDL. The selective oxidation by myeloperoxidase of the N-terminal amine suggests strong steric effects in the approach of substrate to the enzyme catalytic site, an effect that may apply to other macromolecules and to cell surface molecules.

2,4-Dinitrophenol↗

PubMed2001

High levels of HER-2 expression alter the ability of epidermal growth factor receptor (EGFR) family tyrosine kinase inhibitors to inhibit EGFR phosphorylation in vivo.

The epidermal growth factor receptor (EGFR) and HER-2 tyrosine kinases have been implicated in the development, progression, and severity of several human cancers and are attractive targets for therapeutic intervention. SU11925 was developed as a small molecule inhibitor of the tyrosine kinase activity of both EGFR and HER-2. In cellular assays, SU11925 exhibited similar potency against EGFR and HER-2, inhibiting EGF-stimulated EGFR autophosphorylation in A431 (human epidermoid carcinoma) cells with an IC(50) of 30 nM and HER-2 phosphorylation in SK-OV-3TP5 (human ovarian carcinoma) cells with an IC(50) of 38 nM. In contrast to its similar activity against the two targets in cellular assays, approximately 10-fold higher plasma concentrations of SU11925 were required to inhibit HER-2 phosphorylation in HER-2-overexpressing tumors compared with EGFR phosphorylation in EGFR-overexpressing tumors in vivo. Consistent with the proposed mechanism of action of this inhibitor, SU11925 inhibited the s.c. growth of EGFR- and HER-2-dependent tumors in athymic mice at doses that produced substantial inhibition of target receptor phosphorylation in vivo. An unexpected finding from these studies was that higher plasma concentrations of SU11925 were required to inhibit EGFR phosphorylation in vivo in tumors that also express high levels of HER-2 than in tumors that express EGFR alone. This observation, which suggests that it is more difficult to inhibit EGFR phosphorylation in vivo in cells that express high levels of HER-2, was confirmed with ZD1839 (Iressa), a selective EGFR inhibitor that also targets the tyrosine kinase catalytic site. The potential clinical implications of this observation are discussed.

Animals↗

PubMed2001

[Effect of growth hormone on the outcome of ovulation induction in patients with polycystic ovary syndrome].

OBJECTIVE: To study the effect of growth hormone (GH) on the outcome of ovulation induction in patients with polycystic ovary syndrome (PCOS). METHODS: We examined serum sex hormone, GH and insulin like growth factor-II (IGF-II) basal levels by radioimmunoassay in 130 PCOS patients and 107 normal women. In addition, we observed the effect of GH on the outcome of ovulation induction in 7 poor responders to human menopausal gonadotropin (hMG) treatment. RESULTS: The mean serum GH level is (2.50 +/- 1.33) micrograms/L and (1.04 +/- 0.47) micrograms/L respectively in nonobese and obese PCOS patients which were significantly lower than those in controls [(5.30 +/- 2.26) micrograms/L, (2.95 +/- 1.49) micrograms/L respectively, P < 0.05]. The mean serum IGF-II level is (136 +/- 27) nmol/L in the obese PCOS patients, significantly greater than those in nonobese PCOS and controls (P < 0.05). When we used GH with hMG in 7 poor responders, the total amount of hMG required decreased from 1 to 12 amples and the duration of treatment shortened as compared with hMG alone. CONCLUSION: There is abnormal GH secretion in patients with PCOS, GH may improve the outcome of ovulation induction by gonadotropin.

Adult↗

PubMed2001

Apolipoprotein E gene polymorphism and its association with human longevity in the Uygur nationality in Xinjiang.

OBJECTIVE: To study the relationship between apoE alleles and life-span. METHODS: Apolipoprotein E genotypes were determined in 164 unrelated Uygurs including 35 persons aged 90 years or older, 71 men aged 20-35 and 54 men with myocardial infarction by using polymerase chain reaction-restriction fragment length polymorphism. Apolipoprotein E gene polymorphism was analyzed among three groups. RESULTS: There was statistically significant difference in the epsilon 4 allele frequencies among three groups. The epsilon 4 allele frequency in olds was the lowest (0.057), while in patients suffering from myocardial infarction (MI) was the highest (0.213). In MI patients the average age of first attack in epsilon 4 allele carriers was significantly younger than that of non-carries, 51.3 and 58.3 years, respectively (P < 0.05). CONCLUSION: ApoE genotype may have some impact on human longevity.

Adult↗

PubMed2001

Temporal bone fracture and its complications.

OBJECTIVE: To explore the characteristics and treatment of temporal bone fractures and injuries in the medial-inner ear. METHODS: The clinical data of 48 cases of temporal bone fractures admitted to our hospital from January 1989 to November 1999 were retrospectively analyzed. RESULTS: Forty-eight patients with temporal bone fractures accounted for 17.00% of the homochronous craniofacial fractures. Of the 48 cases, temporal bone fractures induced by traffic accidents accounted for 66.67%, capillary fractures for 93.75%, medial inner ear injuries or craniocerebral injuries for 77.08% and hearing loss or tinnitus for 48.00%. The cerebrospinal fluid (CSF) otorrhea and facioplegia accounted for 36.70% and 3.00%, respectively, in the longitudinal fractures, while they were 25.00% and 37.50%, respectively, in the transversal fractures. Primary emergent operations were performed on 46 cases and neurosurgery accounted for 46.00%. Secondary procedures accounted for 16.70%. As a result, 43 cases survived (89.58%) and 5 died (10.41%). CONCLUSIONS: Traffic injury is the first high-dangerous factor for temporal bone fractures, which are often complicated with medial-inner ear or craniocerebral injury. The CSF otorrhea is common in the longitudinal fractures and facioplegia is common in the transversal fractures. The key step is to rescue the life, keep the airway unobstructed and maintain the circulation in the primary emergency treatment.

Adolescent↗

PubMed2001

[Sequential intensified immunosuppressive therapy combining with hematopoietic growth factors in the treatment of severe aplastic anemia].

OBJECTIVE: To explore more effective regimen for reducing early mortality of severe aplastic anemia (SAA) and improving therapeutic effectiveness. METHODS: Antilymphocyte globulin/antithymocyte globulin (ALG/ATG) and cyclosporine A (CsA) (sequential intensified immunosuppressive therapy, SIIST), with or without hematopoietic growth factors (HGFs) were administered to 73 SAA patients in a prospective randomized clinical trial to test the effectiveness of the addition of HGFs for the patients. RESULTS: The response rate of SIIST with HGFs group was significantly higher than that of SIIST alone group (89.2% vs 63.9%), with lower rates of early infection (24.3% vs 55.3%) and mortality (4.0% vs 16.7%), shorter duration of cytopenia and blood transfusion dependence and faster recovery of bone marrow hematopoiesis. The addition of HGFs to SIIST was tolerated well in all patients. There was no difference in the treatment outcome of the two groups with GM-CSF plus Epo or G-CSF plus Epo. CONCLUSION: The use of HGFs in combination with SIIST could reduce early infection and mortality rates and, therefore, improve the response rates in SAA patients.

Adolescent↗