Biomedical subjects

B Zhang

Publications and source records attributed to B Zhang.

At least 541 records · Page 30Linked to original sources

PubMed1995

Calcium-dependent plateau potentials in a crab stomatogastric ganglion motor neuron. II. Calcium-activated slow inward current.

1. Using intracellular recording and voltage-clamp techniques, we examined the biophysical properties of a Ca(2+)-activated slow inward current and its physiological role in plateau potential generation in the dorsal gastric (DG) motor neuron of the stomatogastric ganglion in the crab, Cancer borealis. 2. As shown in the accompanying paper, a brief puff of serotonin (5-HT) evoked a plateau potential in the DG neuron. Intracellular loading of the Ca2+ chelator ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) prevented 5-HT from evoking a plateau potential. On the contrary, rapid increase of intracellular Ca2+ by photolysis of caged-Ca2+ (bound to DM-nitrophen) evoked a plateau response in DG bathed in normal saline. 3. Extracellular tetrodotoxin (TTX), tetraethylammonium (TEA), 4-aminopyridine (4-AP), and Cs+ and intracellular iontophoresis of Cs+ were used to block voltage-dependent INa, IK, and Ih. Under these conditions we voltage clamped DG using two electrodes and isolated a long-lasting tail current after a short depolarization of the cell. 4. The reversal potential of the slow tail current was extrapolated to be -27 +/- 3.5 (SE) mV. Na+ substitutions with choline+, tris(hydroxymethyl)aminomethane+ (Tris+) or n-methyl-glucamine+ (NMG+) did not significantly affect the reversal potential or the amplitude. 5. The slow tail current was Ca2+ dependent. It was reduced or abolished by the Ca2+ channel blocker Co2+, intracellular injection of EGTA, and by Ba2+ replacement of Ca2+ as the charge carrier. The activation and deactivation of this current do not show an apparent dependence on voltage. 6. When the voltage-dependent Na+, K+, and Ca2+ channels were blocked, a brief puff of caffeine evoked a slow depolarization. In voltage clamp, caffeine evoked a slow inward current with an apparent conductance increase. This current was reduced by intracellular EGTA. The current-voltage (I-V) relationship of the caffeine-evoked current was linear with a reversal potential of -25 +/- 4.8 mV. This was not statistically different from the reversal potential of the depolarization-evoked tail current. 7. 5-HT enhanced the depolarization-evoked slow tail current but had no effect on the caffeine-evoked slow inward current. 8. We conclude that the slow tail current is a Ca(2+)-activated nonselective current, similar to the Ca(2+)-activated nonspecific cation currents described in other preparations. This current appears to play an important role in plateau generation and maintenance in DG. 5-HT has no direct effect on the properties of this current, but it indirectly enhances the current through an increase of voltage-dependent Ca2+ current.

Animals↗

PubMed1995

Antidiabetic thiazolidinediones block the inhibitory effect of tumor necrosis factor-alpha on differentiation, insulin-stimulated glucose uptake, and gene expression in 3T3-L1 cells.

Tumor necrosis factor-alpha (TNF alpha) is a cytokine implicated in the development of septic shock, cachexia, and other pathological states. Recent studies indicated a direct role for adipose expression of TNF alpha in obesity-linked insulin resistance and diabetes. Pioglitazone, CP-86,325 (CP), AD-5075, CS-045, ciglitazone, and englitazone are members of a new class of insulin-sensitizing thiazolidinedione derivatives with in vivo antidiabetic activities. To test whether these agents antagonize the effect of TNF alpha, 3T3-L1 cells were induced to differentiate in the presence of TNF alpha with or without thiazolidinedione derivatives. Incubation of 3T3-L1 cells with TNF alpha alone completely inhibited adipocyte conversion and expression of fatty acid-binding protein messenger RNA (mRNA). However, coincubation of TNF alpha-treated cells with CP (1 microM), AD-5075 (1 microM), pioglitazone (10 microM), or CS-045 (10 microM) blocked these effects. Long term incubation of 3T3-L1 adipocytes with a low dose of TNF alpha (50 pM) significantly decreased the levels of the adipocyte/muscle-specific glucose transporter (GLUT4) and the CCAAT enhancer-binding protein mRNAs, but did not affect expression of the ubiquitously expressed glucose transporter (GLUT1) or lipoprotein lipase mRNAs. Incubation of 3T3-L1 adipocytes with TNF alpha also inhibited insulin-stimulated 2-deoxyglucose uptake as well as expression of GLUT4 protein. Furthermore, in 3T3-L1 adipocytes, incubation with TNF alpha attenuated the expression of fatty acid-binding protein mRNA in a time- and dose-dependent manner. These inhibitory effects were partially or completely blocked by coincubation of the cells with CP. These results implicate that the insulin-sensitizing agents may exert their antidiabetic activities by antagonizing the inhibitory effects of TNF alpha.

3T3 Cells↗

PubMed1995

[Sensitivity of Plasmodium falciparum to seven antimalarials in China-Laos border].

The sensitivity of P. falciparum to chloroquine (CHL), piperaquine (PIP), artesunate (ATS), dihydroartemisinine (DAT), artemether (ATM), arteether (ATE) and pyronaridine (PRN) were assayed by in vitro microtechnique in China-Laos border in 1992. The resistance rates of isolates from the south of Yunnan of China in the border were 97.0%, 96.4%, 12.5%, 16.0%, 6.3% and 34.5%, respectively; ID50 were 119.0, 320.0, 7.2, 5.4, 295.0, 74.4 and 31.9 nmol/L, ID95 were 625.0, 2426.0, 42.2, 36.6, 767.0, 371.1 and 325.2 nmol/L. The resistance rates of isolates from the north border of Laos were in order 9/10, 8/10, 1/5 to CHL, PIP, PRN, ID50 were 114.0, 166.9, 16.4 nmol/L, ID95 were 570.0, 631.1 and 107.7 nmol/L. All the isolates from Laos were sensitive to ATS, DAT, ATM and ATE. ID50 were 5.0, 4.4, 91.6 and 56.7 nmol/L, ID95 were 23.4, 11.1, 3276.1 and 223.9 nmol/L, respectively. The results indicate that P. falciparum in the border was highly resistant to CHL and PIP, while most of the isolates were susceptible to the other 5 of the above-mentioned drugs. A comparison between the isolates from China and Laos showed that there was no significant difference in resistance degree to CHL but the sensitivity of isolates from China to other 6 drugs was lower than those from Laos.

Animals↗

PubMed1995

Treatment of intracranial germinoma.

In 31 patients with intracranial germinoma who received radiotherapy, 15 were operated on, and 13 were treated with CSF shunt (7) and external ventricular drainage (6). After radiotherapy, clinical symptoms were improved in 93.5% of the patients. Follow-up of 16 patients for 2 to 14 years showed better results. We consider that initial treatment with radiotherapy may be appropriate for germinomas because of its high radiosensitivity. If hydrocephalus developed, external ventricular drainage combined with radiotherapy was performed, but shunting operation might be avoided because of potential peritoneal seedings of germinomas. In addition to chemotherapy, re-irradiation is an effective method for recurrent germinoma.

Adolescent↗

PubMed1995

[Quantitative study of myocardial mitochondrial DNA4977 deletion in rheumatic heart disease and its significance].

To better understand the mechaenisms of cardiac function damaged by chronic hypoxemia in rheumatic heart disease, we investigated the level of the 4977 base pair mitochondrial DNA (mtDNA4977) deletion in 16 patients with rheumatic heart disease (RHD) by using polymerase chain reaction (PCR). Myocardial malondialdehyde (SOD) activity was also measured. In control group, mtDNA4977 deletion appeared after 45 years old and reached a maximum of 0.0042%. A higher level of mtDNA4977 deletion (0.02%-1.26%) was found in RHD group. Because mtDNA4977 deletion removes 8 genes coding for subunits of complexes of respiratory chain, its deletion can inhibit oxidative phosphorylation, reduce ATP production and hinder the recovery of cardiac function. In addition, myocardial MDA content increased and SOD activity decreased in the RHD group as compared with the control group. This indicates that the generation of oxygen free radicals enhances and the elimination of free radicals reduces. Oxygen free radical can be an important factor in myocardial mitochondrial DNA injury and lead to mitochondrial DNA deletion.

Adult↗

PubMed1995

Experimental study of fat embolism syndrome.

To find the diagnostic methods for subclinical stage fat embolism syndrome (FES), we established an experimental animal model, using fat intravenous injection. The fat was obtained from the long bone marrow cavity of homologous dogs. Fourteen healthy mongrel dogs received 0.7 ml/kg fluid marrow fat injection and all of them developed FES within 48 hours. The blood samples collected from the pulmonary vessels by floating catheter and peripheral vein at different time intervals were subjected to blood gas analysis and were frozen sectioned rapidly. The sections were stained with oil red 'O'. Positive result was seen 2 hours after fat injection in both pulmonary and peripheral blood. Computer image analysis showed that the number and diameter of fat droplets in pulmonary vascular blood were obviously higher and larger than those in peripheral vein blood. These findings were correlated well with blood gas changes and clinical features. The demonstration of fat droplets from pulmonary or peripheral blood by oil red 'O' staining combined with blood gas changes (PaO2 < 7.99 kPa, P(A-a)O2 > 6.09 kPa) may be rapid and specific for early diagnosis of FES. In the treatment of FES, dexamethason can stabilize the cellular membranes and inhibit the neutrophil response to fatty acid and the release of phospholipase A2, arachidonic acid and platelet aggregation.

Animals↗

PubMed1995

[Mutation of P53 gene in a highly metastatic human lung cancer cell line].

PG cell line, derived from a lung giant cell carcinoma, has the characteristics of rapid growth and high tumorigenicity. When transplanted to nude mice, spontanious metastasis to lung and lymphnode is high in frequency and stable. To understand the molecular basis of PG's biological behaviors, expression of tumor suppressor gene p53 was studied. It was found that expression of p53 protein was increased as demonstrated by immunohistochemical stainning. A change in polymorphsim in exon 7 of p53 gene was detected by nonisotopic PCR-SSCP, suggesting a change in base composition. Thermal cycling sequencing of both strands of exon 7 demonstrated a transversion of CGG to CTT at codon 248. Similar study with the same methods on Ki-ras oncogene was done, but no mutation was found. The relationship between p53 gene mutation and the metastatic potential of PG cells needs further exploration.

Animals↗

PubMed1995

[The roles of two kinds of membrane vesicles in the formation of annulate lamellae and nuclear envelopes in a cell-free system from Xenopus egg extracts].

The eggs of Xenopus laevis were activated to complete their second meiosis and enter interphase by calcium ionophore A 23187. Then they were centrifuged at 10,000 g to get activated Xenopus egg extracts. Chromatin structure could form in such an extracts after exogenous Lambda DNA was added, and nuclear envelopes (NEs) could assemble around the chromatin. Furthermore, annulate lamellae (AL), a NE-like membrane structure, could form in chromatin-free regions simultaneously. After large amounts of observation and analysis at ultrastructural level, we propose that both AL and NEs assemble in the extracts by the fusion of membrane vesicles. There were two kinds of membrane vesicles in Xenopus egg extracts, small rough vesicles with diameters of 200 nm and large smooth vesicles. They had many differences in morphology, size and membrane structure. However, they both participate in the formation of AL and NEs, 200 nm membrane vesicles first fused each other to become parallel double membrane cisternae, nuclear pore complexes assembled in the double membranes in the mean time. The fusion of large smooth vesicles with the double membrane cirternae led to the growth of AL and the maturity of NEs. During the formation of NEs, large smooth vesicles were easily observed to link two neighboring double membrane fragments by fusing with them, so that integrated nuclear envelope could form. 200 nm small rough vesicles could attach to the surface of chromatin to start the assembly of nuclear envelopes, while others could fuse each other at chromatin-free regions and these fusion resulted in the formation of annulate lamellae.

Animals↗

PubMed1995

[Combined antitumor effect of tumor-infiltrating lymphocytes and tumor necrosis factor alpha].

Tumor-infiltrating lymphocytes (TILs) were isolated from 8 solid tumors by means of in vitro digestion and discontinuous density gradient centrifugation. By incubating TILs in the presence of 6000 Iu/ml rIL-2 and 500u/ml rTNF alpha, It's demonstrated that rTFN alpha could enhance the proliferation of TILs, promote the proportion of TILs in S-phase and G2 M-phase, enhance the percentage of CD3+ and CD8+ cells, up-regulate the expression of IL-2R, as well as enhance the cytotoxicity of TILs against autologous and allogenic tumors both in vitro and in vivo. The results are of significance for increasing immunotherapy effects and decreasing the adverse effects of certain cytokines.

Animals↗

PubMed1995

Encircling suture method in the treatment of femoral venous valvular incompetency.

Many patients with chronic venous insufficiency syndrome caused by the "relative valvular incompetency" with venous dilatation. Eighty-six per cent of the cases can be cured by reducing the femoral venous diameter by simply using the encircling suture method just distal to the first femoral valvular sinus. Our preliminary results suggest that such a method of surgical treatment is simple and efficient.

Adult↗

PubMed1995

[Studies on mode of human infection with Echinochasmus liliputanus].

Epidemiological survey and experimental studies on the mode of human infection with Echinochasmus liliputanus were carried out in Chenqiaozhou Village, Hexian County, Anhui Province in 1992. The results showed that humans could be infected through drinking unboiled water containing E.liliputanus cercaria or eating raw fish containing the metacercaria. The infection rates of E. liliputanus were 1.5% in the inhabitants who did not drink raw water, and 20.1% in those who used to drink raw water. It was only the cercaria, not the metacercaria that was detected in the water from ponds of this village. None of the investigated inhabitants ate uncooked fish. The results indicated that drinking raw water containing E.liliputanus cercaria was a major way through which a humans were infected and eating food containing the metacercaria was a minor mode of human infection.

Animals↗

PubMed1995

[Acridine mutagen ICR-170 induced developmental suppression of ovary and vitelline gland in female Schistosoma japonicum].

Mice of Kunming strain were infected with Schistosoma japonicum cercariae previously incubated with various concentrations of acridine mutagen ICR-170 for different time durations. At 6 weeks after infection, the mice were autopsied. The results showed that 24 out of 28(85.7%) adult female worms had deformed or lacked ovaries and vitelline glands when the cercariae were treated with the agent at a concentration of 10 micrograms/ml and incubated at 30.5 degrees C for 30min. No apparent changes were observed in the male worms inhabiting the mesenteric and portal veins with the females worms in their gynecophoral canals. The mutagenized female schistosomes obtained from the present experiment might be served as another form of attenuated worms for the induction of protective immunity.

Aminoacridines↗

PubMed1995

[Characteristics and recent trends in endemicity of human parasitic diseases in China].

An analysis of the nationwide survey of the distribution of human parasites in the light of the literature previously published, two major trends in the endemicity of parasitic diseases in China was observed. For one trend, the infection rate of E. histolytica, Fasciolopsis buski and soil-transmitted helminthasis etc. declined markedly. The second trend was that the prevalence of food-transmitted parasitic diseases (Trichinella spiralis, Clonorchis sinensis, Paragonimiasis, cysticercosis) and hydatidosis was increasing. The relationship between the social economic factors and the two trends were discussed.

Animals↗

PubMed1995

[Clinical observation of oral cefuroxime axetil for treating acute gonorrhoea].

The effectiveness of a single oral dose of Zinnat (cefuroxime axitil) in treating acute gonorrhoea was assessed in 12 men and 2 women who received 1.0 g. the cure rate was 85.7% (12/14). No adverse effect was found. Zinnat was effective, convenient, well tolerated and valuable drug in treatment of acute gonorrhoea.

Acute Disease↗

PubMed1995

[Conservative surgery and radiotherapy for early breast cancer].

Thirty-six patients with early stage breast cancer were treated by quadrantectomy, axillary dissection and radiotherapy (CSRT) between October 1987 and May 1990. The median follow-up was 48 months. Overall survival was 100%. 2 had local recurrence in the breast, both patients were stage IIB (T2N1), the number of positive node were 6/12 and 3/11, respectively. The cosmetic results of the breast are excellent and good in 91%. We concluded that CSRT provides good cosmetic results and better local tumor control for early breast cancer patients, but good results depend on strict adherence to indication of treatment, fair surgical techniques and radiotherapeutic measures.

Adult↗

PubMed1995

[Cloning of a cluster of genes encoding coli-surface antigen 6(CS6) of human enterotoxigenic E. coli].

A gene library was constructed from large plasmid DNA of wild strain E519/66A of human enterotoxigenic Escherichia coli (ETEC). Positive colonies containing CS6 antigen were obtained. The CS6 gene fragment was identified by restriction endonuclease mapping. It was approximately 4.6 kb in length and responsible for encoding CS6 genes and regulating the CS6 antigen. Two forms of fimbriae protein with different molecular weight were produced by the selected clones. Both of them could react with the same CS6 antiserum. So we expect to use the recombinant strain as candidate for human ETEC vaccine development, and it is also useful for further research on the expression and regulation of genes encoding CS6 fimbriae protein.

Antigens, Bacterial↗

PubMed1995

The treatment of pain in bone metastasis of cancer with the analgesic decoction of cancer and the acupoint therapeutic apparatus.

The pain in 286 cases of bone metastasis of cancer was treated with an analgesic decoction of herbal drugs in combination with the Acupoint Therapeutic Apparatus that generated low frequency electric impulses into the acupoints. This series of patients comprised 104 cases of medium pain and 182 cases of severe pain, which was practically or completely relieved in 17 or 29 minutes respectively after the treatment; the total effective rate was 74.2% for 212 cases, and the duration of analgesic effect lasted 2.7 hours to 5.2 hours, averaging 3.6 hours. The cases that needed considerable dosages of analgesic tablets or sedatives markedly reduced their requests of such drugs. Determination of bone marrow stem cells indicated that the herbal treatment produced effects of promoting and protecting the stem cells. The rate of lymphocyte transformation was 45-76% before the treatment and rose to 57-96% after the treatment, demonstrating an increase of 15.2%, which was statistically significant (P < 0.001). The analgesic effect of the decoction was not correlated to the age and sex of the patients or the variety of cancer, except that it was not effective for uterine carcinoma. The main side effects included nausea, vomiting, somnolence, and numbness of the tongue.

Acupuncture Therapy↗

PubMed1995

The influence of 5-fluorouracil on the endothelium in small arteries. An electron microscopic study in rabbits.

5-Fluorouracil (5-FU) is a widely used antineoplastic agent. 5-FU induced cardiotoxicity is a still relatively unknown side-effect of this drug. This phenomenon could be due to a direct cytotoxic effect on the endothelial cells. We tested this hypothesis in an experimental study in rabbits, by scanning or transmission electron microscopic evaluation of endothelium in small arteries (the central artery of the ear) after in vivo treatment with 5-FU. Both local and systemic effects of 5-FU on endothelium were studied 15, 30, 60 and 120 minutes after intra-arterial or intraperitoneal treatment. Perfusion fixation at physiological pressure and temperature was used in order to minimize damage to the endothelium during the preparation procedure. Eighteen rabbits weighing 2.5-3.0 kg were used, and 6 animals served as controls. The following parameters were evaluated: vessel wall and endothelial cell contraction, cell edema, cytolysis, occurrence of denuded areas, platelet adhesion/aggregation and fibrin formation. For the description of each parameter a scale of negative points was used. Irreversible cell damage was observed in 5-FU treated animals: disruption of the endothelial sheet and patchy exposure of the subendothelium, sometimes as a focus for thrombus formation. Our findings support the hypothesis that the thrombogenic effect of 5-FU secondary to its direct cytotoxic effect on endothelium might be one of the pathophysiological mechanisms behind 5-FU induced cardiotoxicity.

Animals↗