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Biomedical subjects

J Guan

Publications and source records attributed to J Guan.

104 records · Page 6Linked to original sources
PubMed1995

[Radiolabelling and assay of Chinese agkistrodon acutus venom with carrier-free Na 125I].

Chinese agkistroden acutus venom (CAAV) was radiolabelled with carrier-free Na 125I by the method of Iodogen. The specific activity and radiochemical purity for radiolabelled products were 4236.5 x 10(10) Bq/mmol and 98%, respectively. Each CAAV molecule carried 0.52 125I atom. Physical and chemical characterization of radiolabelled CAAV was similar to unradiolabelled CAAV. Binding analysis showed that 125I-CAAV was bound to platelet in a saturable manner. Binding sites per platelet were 13,255 +/- 6292/platelet. The dissociation constant (Kd) was 3.2 +/- 0.69 x 10(-10) mol/L. These results are similar to binding sites of other snake venom on platelet. The investigation showed that radiolabelled CAAV made by our laboratory was useful for radioligand binding assay.

Agkistrodon↗
PubMed1995

[Molecular cloning of cellulase gene from the bacillus].

The CMCase gene from the Bacillus sp. strain E2 was cloned into E. coli DH5 alpha F' using plasmid pBR322 as a vector. Recombinant plasmid pBG3 was isolated from transformants producing CMCase, and the cloned CMCase gene was found to be in a 4.0kb HindIII fragment. The CMCase gene was subcloned in a functional state on a 2.4kb DNA fragment. The optimum pH and temperature for activity of CMCase encoded by pBG3 were pH 6.5 and 55 degrees C respectively. The CMCase could not hydrolyze any natural cellulose examined. Eighty-three percent of the CMCase was detected in the inner cellular fraction, 9% and 8% were in the periplasmic space and medium respectively. Result of Southern hybridization indicates that the cloned DNA fragment was derived from Bacillus sp. strain E2 chromosomal DNA.

Bacillus↗
PubMed1994

Neuronal rescue with transforming growth factor-beta 1 after hypoxic-ischaemic brain injury.

Transforming growth factor-beta 1 (TGF-beta 1) mRNA is induced from 5 h to 3 days following hypoxic-ischaemic brain injury. Cell death also develops during this time suggesting that extracellular accumulation of this peptide may be involved in the processes that regulate cell loss. We examined the effect of rhTGF-beta 1 (0,2.5, 10,50 ng) injected into the cerebral lateral ventricle of rats 2 h after severe hypoxic-ischaemic brain injury. Histological outcome and B4-isolectin histochemistry were assessed 5 and 2 days, respectively following hypoxia. Treatment with 10 ng TGF-beta 1 reduced the microglia reaction (p < 0.05), the magnitude of neuronal loss (p < 0.01) and the area of cortical infarction (p < 0.05). Exogenous TGF-beta 1 given soon after hypoxic-ischaemic brain injury may have therapeutic potential and act by inhibiting the microglial reaction.

Animals↗
PubMed1994

Two models for determining the mechanisms of damage and repair after hypoxic-ischaemic injury in the developing rat brain.

Hypoxic-ischaemic (HI) brain injury can lead to selective neuronal loss or pannecrosis. Different mechanisms of damage and recovery may be associated with either pattern of cell loss. Two preparations were developed to investigate the role of growth factors and other mechanisms associated with either of these patterns of damage in the developing brain. Twenty-one-day-old Wistar rats underwent permanent unilateral right carotid artery ligation. Following surgery, ligated rats were warmed for 2 h at 34 degrees C with 85 +/- 5% relative humidity and then exposed to either 15 or 60 min of 8% O2. The rats were killed and brains perfusion fixed 5 days post-hypoxia for histological analysis. Rats exposed to 15 min of hypoxia-ischaemia suffered no mortality and 90% developed selective neuronal loss in the frontoparietal cortex and hippocampal CA1 region of the ipsilateral hemisphere. Rats exposed to 60 min of hypoxia consistently developed cortical pannecrosis and cellular loss in the striatum, thalamus, hippocampus and dentate gyrus of the ipsilateral hemisphere. The advantage of these models were ease of preparation, consistent neuronal loss scores and low mortality. The ability to induce either selective neuronal loss or pannecrosis provides an opportunity to investigate the mechanisms of damage or recovery associated with each pattern of cell loss.

Animals↗
PubMed1993

The effects of IGF-1 treatment after hypoxic-ischemic brain injury in adult rats.

Intraventricular injection of insulin-like growth factor 1 (IGF-1) 2 h after hypoxic-ischemic injury reduces neuronal loss. To clarify the mode of action, we compared histological outcome between treatment groups in the following three studies: 0, 0.5, 5, and 50 micrograms IGF-1 given 2 h after injury; 0 and 20 micrograms IGF-1 given 1 h before; and 20 micrograms IGF-1 and insulin or vehicle alone given 2 h after. Unilateral hypoxic-ischemic injury was induced in adult rats by ligation of the right carotid and exposure to 6% O2 for 10 min. Histological outcome was evaluated in the cortex, striatum, and hippocampus 5 days later. Five to 50 micrograms IGF-1 reduced the incidence of infarction and neuronal loss in a dose-dependent manner in all regions (p < 0.05), and 50 micrograms reduced the infarction rate from 87 to 26% (p < 0.01). Pretreatment did not alter outcome. IGF-1 improved outcome compared with equimolar doses of insulin (p < 0.05) and did not affect systemic glucose concentrations or cortical temperature. The results indicate that the neuronal protective effects of IGF-1 are specific and are not mediated via insulin receptors, hypothermia, or hypoglycemic mechanisms. Centrally administered IGF-1 appears to provide worthwhile trophic support to cells within most cerebral structures after transient hypoxic-ischemic injury.

Animals↗
PubMed1993

Hepatitis B control in China: knowledge and practices among village doctors.

OBJECTIVES: To guide development of a hepatitis B control program in China, we investigated village doctors' sterilization practices, injection use, vaccination levels, and knowledge and counseling skills. METHODS: The head doctor from each village health station in a rural county (n = 260) completed a self-administered questionnaire. RESULTS: Of the respondents, 94.2% reported adequate sterilization of needles; however, inadequate sterilization of syringes and acupuncture needles was common. Injections were found to be frequent and profitable. Of head doctors, 16.2% reported that most infants in their villages are vaccinated against hepatitis B. There was very high knowledge of modes of hepatitis B transmission, but it was not used to formulate advice for a hypothetical carrier. Knowledge of the consequences, prevalence, and use of condoms to prevent sexual transmission was lower. CONCLUSIONS: The sterilization of acupuncture needles, reuse of syringes, and frequent injections are practices that may transmit the hepatitis B virus. Research into issues of vaccine acceptance is needed to expand immunization. A review of treatment practices and better training in counseling for village doctors is suggested.

Acupuncture Therapy↗
PubMed1992

A role for IGF-1 in the rescue of CNS neurons following hypoxic-ischemic injury.

Three days after unilateral hypoxic-ischemic injury in infant rats insulin-like growth factor 1 (IGF-1) production by astrocytes was enhanced in the injured region. This was associated with increased expression of mRNA for IGF binding protein-3 but not for binding protein-1. In adult rats a single lateral cerebroventricular injection of IGF-1 two hours following a similar injury markedly reduced neuronal loss. It is suggested that endogenous IGF-1 is neurotrophic and that centrally administered IGF-1 may have therapeutic potential for brain injury.

Animals↗
PubMed1992

[Alpha 2 megaloglobulin inhibits the activation of rabbit platelet by Chinese Agkistrodon acutus venom].

An in vitro study of alpha 2-mengaloglobulin (alpha 2MG) in the inhibition of the activation of washed rabbit platelet by Chinese Agkistrodon acutus venom (CAAV) was reported. Results showed that CAAV induced aggregation rate of washed rabbit platelet was positively related to the CAAV concentration, and the maximal aggregation rate was 43.8 +/- 9.9% at the concentration of 100 micrograms/ml. Meanwhile the release of serotonin (5-HT) and platelet factor 4(PF4) from the platelet reached maximum at the CAAV concentrations of 0.81 +/- 0.07 microgram/ml and 39.08 +/- 2.78%, respectively. Platelet aggregation and the release of 5-HT and PF4 induced by CAAV could be inhibited by the addition of 0.25% alpha 2 MG into the platelets both 1 minute before and 1 minute after the addition of CAAV. When alpha 2 MG was added to the platelets 1 minute prior to the addition of CAAV, the platelet aggregation and the ultrastructural changes which could be induced by CAAV were not observed, and the morphology of the rabbit platelets was the same as that of the normal counterparts.

Animals↗
PubMed1991

[The influence of Chinese Agkistrodon acutus enzyme (CAAE) on the functions of washed human platelets].

The effects of the activation and influence of CAAE on washed human platelets were investigated. Our findings were: (1) CAAE could induce aggregation and alpha-granule release reaction in the washed human platelet suspension; thus it could activate the platelets; (2) the aggregation effect of CAAE was inhibited by albumin and affected by Ca2+, Mg2+ concentration; (3) heparin and/or AT III did not inhibit the aggregation activation of CAAE, but alpha 2MG markedly inhibited it; (4) the aggregation activity of CAAE was associated with the serine protease activity. The mechanism of CAAE-induced aggregation mainly follows the prostaglandins-endoperoxides thromboxane A2 pathway.

Animals↗
PubMed1990

[A processing study of herba Cistanches].

The synthetic rate of DNA in the liver and spleen and metallic microelements have been determined for the different preparations of Herba Cistanches. The results show that the salted Herba Cistanches in steamed from affects the synthetic rate of DNA in "Yang-Deficiency" animal models, with trace elements Zn, Mn, Cu, and Fe higher in content than other traditional preparations.

Animals↗