The movement of IGF-I into the brain parenchyma after hypoxic-ischaemic injury

The movement of peptides from CSF into the parenchyma is thought to be slow and diffusion limited. However IGF-I can reduce neuronal loss at distal sites when given centrally 2 h after hypoxic-ischaemic (HI) injury. The present study determined the distribution of [3H]IGF-I given into the lateral ventricle after unilateral HI injury in adult rats. Radioactivity in the injured cortex peaked immediately after administration then rapidly declined. Autoradiography demonstrated radioactivity in the perivascular spaces and in the corpus callosum and external capsule of the injured hemisphere. HPLC and radioimmunoassay confirmed a rise in intracerebral IGF-I levels (from 159 +/- 9 to 401 +/- 88 ng g-1). These data suggest that injury can enhance the movement of IGF-I into the cerebrum via the white matter tracts and perivascular spaces.

Rats with portal-caval vein transposition show hyperinsulinemia and insulin resistance

To compare the metabolic effects of portal and systemic delivery of insulin, we used portal-caval transposition (PCT) in rats to provide total systemic diversion of splanchnic venous blood. PCT rats exhibited normal weight gain, liver histology, liver-function tests, glycosylated hemoglobin, arterial blood pressure, and hepatic blood flow. Mean liver weight relative to body weight was 12% lower in PCT rats than in sham-operated control (CTR) rats 30 days following transposition. Indwelling venous catheters were established to facilitate metabolic studies in conscious, minimally restrained animals. Postabsorptive plasma glucose and C-peptide (CPEP) levels were similar in PCT and CTR rats; however, postabsorptive immunoreactive insulin (IRI) levels were elevated in PCT rats (67 +/- 3.1 v 49 +/- 3.5 pmol.L-1, P < .002, n = 11 v 11), as were postabsorptive plasma glucagon levels (570 +/- 67 v 240 +/- 11 ng.L-1, P < .001, n = 11 v 16) at similar body weights. The postabsorptive CPEP/IRI concentration ratio was lower in PCT than in CTR rats (4.0 +/- 0.3 v 6.0 +/- 0.6, P < .02), suggesting reduced hepatic extraction of insulin. Insulin sensitivity (IS), determined by minimal model analysis of frequently sampled intravenous glucose tolerance tests yielding the sensitivity index (SI), was reduced in PCT compared with CTR (61 +/- 5.6 v 86 +/- 9.0 (mumol.L-1)-1.min-1, P < .04, n = 9 v 10). During euglycemic-hyperinsulinemic clamps, glucose infusion rates (GIRs) from 60 to 120 minutes were lower in PCT than in CTR rats (6.0 +/- 0.3 v 8.0 +/- 0.4 g.kg-1.min-1, P < .002, n = 9 v 7) with matching plasma IRI levels, confirming the reduced IS in PCT rats. Areas under the concentration curves ([AUCs] 0 to 150 minutes) for glucose tolerance tests (gavage) indicated that plasma glucose excursion was similar in PCT and CTR rats whereas AUC IRI was significantly higher in PCT than in CTR rats (23 +/- 1.3 v 18 +/- 0.6 nmol.L-1.min, P < .009, n = 11 v 11). However, AUC CPEP for oral glucose tolerance tests was lower in PCT than in CTR rats (55 +/- 3.4 v 68 +/- 4.8 nmol.L-1.min, P < .05), indicating decreased insulin secretion. Thus, the mean ratio AUC CPEP/AUC IRI was significantly lower in PCT rats (2.5 +/- 0.2 v 3.8 +/- 0.3, P < .002), again suggesting reduced hepatic extraction of insulin. Thus, euglycemia after PCT was accompanied by elevated postabsorptive and glucose-stimulated levels of IRI in systemic blood, postabsorptive hyperglucagonemia, and decreased insulin secretion in response to glucose challenge (gavage), with diminished hepatic extraction of insulin and decreased IS. The PCT model illustrates the insulin-resistant adaptive state that results from systemic delivery of insulin, and indicates the importance of hepatic portal delivery of insulin and possibly of other gastroenteropancreatic hormones in the maintenance of IS and physiological metabolic control.

[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.

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.

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.

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.

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.

[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.

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.

[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.

[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.