Biomedical subjects

Bi Hu

Publications and source records attributed to Bi Hu.

4 recordsLinked to original sources

PubMed2005

[17β-estradiol protects against injury of aortic relaxation and contraction in ovariectomized rats with insulin resistance induced by fructose].

The purpose of the present study was to investigate the effect of 17beta-estradiol (17beta-E(2)) on the structure and relaxation and contraction activity of thoracic aortas in ovariectomized rats with insulin resistance induced by fructose. Ovariectomized mature female Sprague-Dawley rats were fed with high fructose diet for 8 weeks to induce insulin resistance. Physiological dose of 17beta-E(2) (30 mug/kg) was injected subcutaneously every day for 8 weeks. Systolic blood pressure (SBP) was measured by use of tail-cuff. Serum nitric oxide (NO), estradiol (E(2)), fasting blood sugar (FBS) and fasting serum insulin (FSI) were measured respectively in each group. The insulin sensitive index (ISI) was calculated. The thoracic aortas were fixed in formalin, sliced and HE dyed. The structure of thoracic aortas, lumen breadth, media thickness, media thickness/lumen breadth ratio and media cross-section area were measured. The contraction response of thoracic aorta rings induced by L-phenylephrine (PE) and the relaxation response of thoracic aorta rings induced by ACh and sodium nitroprusside (SNP) were measured. To explore the mechanism, nitric oxide synthase (NOS) inhibitor N-nitro-L-arginine methyl ester (L-NAME) was used. The results obtained are as follows: (1) 17beta-E(2) protected against the effect of high fructose diet, which caused an increase in SBP, hyperinsulinemia and a decrease in ISI in ovariectomized rats. (2) The structure of thoracic aortas had no significant difference among the groups. (3) Compared with the ovariectomized group (OVX) or fructose fed group (F), serum nitric oxide was significantly reduced, the contraction response of thoracic aorta rings to PE was enhanced and the relaxation response to ACh was depressed significantly in ovariectomized+fructose fed group (OVX+F). The effect of high fructose was reversed by 17beta-E(2). After pretreatment with L-NAME, the effect of 17beta-E(2), which enhanced the relaxation response of thoracic aorta rings to ACh in ovariectomized+fructose+17beta-E(2) group (OVX+F+E(2)), was partly blocked. (4) The relaxation response of thoracic aorta rings to SNP had no significant difference among the groups. (5) The contraction response of thoracic aorta rings without endothelium to PE had no significant difference among the groups. These findings suggest that 17beta-E(2) may provide protection against the effect of high fructose diet, which causes hypertension, dysfunction of endothelial cells and insulin resistance. The mechanism of this effect of 17beta-E(2) could be partly associated with the increase of NO by NOS pathway, or associated with the decrease in the level of systolic blood pressure and serum insulin, and the improvement of insulin resistance.

Animals↗

PubMed2005

Assessing functioning of the prefrontal cortical subregions with auditory evoked potentials in sleep-wake cycle.

Our previously observations showed that the amplitude of cortical evoked potentials to irrelevant auditory stimulus (probe) recorded from several different cerebral areas was differentially modulated by brain states. At present study, we simultaneously recorded auditory evoked potentials (AEPs) from the dorsolateral prefrontal cortex (DLPFC) and the ventromedial prefrontal cortex (VMPFC) in the freely moving rhesus monkey to investigate state-dependent changes of the AEPs in the two subregions of prefrontal cortex. AEPs obtained during passive wakefulness (PW), active wakefulness (AW), slow wave sleep (SWS) and rapid-eye-movement sleep (REM) were compared. Results showed that AEPs from two subregions of prefrontal cortex were modulated by brain states. Moreover, a significantly greater increase of the peak-to-peak amplitude (PPA) of N1-P1 complexes appears in the DLPFC during PW compared to that during AW. During REM, the PPA of N1-P1 complexes presents a contrary change in the two subregions with significant difference: a significant increase in the DLPFC and a slight decrease in the VMPFC compared to that during AW. These results indicate that the modulation of brain states on AEPs from two subregions of the prefrontal cortex investigated is also not uniform, which suggests that different subregions of the prefrontal cortex have differential functional contributions during sleep-wake cycle.

Animals↗

PubMed2005

[Effects of rosiglitazone on aortic function in rats with insulin resistant-hypertension].

Rosiglitazone (ROSI), thiazolidione peroxisome proliferator-activated receptor-gamma (PPAR-gamma) activator, reduces insulin resistance in patients with type 2 diabetes (T2DM). It also improves vascular reactivity in T2DM patients and some animal models by unclear mechanisms. In order to investigate the effect of ROSI on aortic systolic and diastolic function of insulin resistant-hypertensive rats (IRHR) and the underlying mechanism, male Sprague-Dawley (SD) rats were fed with high fructose (HF) for 8 weeks to induce IRHR model. To verify IRHR model, systolic blood pressure (SBP), fasting blood sugar (FBS), fasting serum insulin (FSI) were measured respectively in each group, and insulin sensitive index (ISI) was also calculated. Subsequently, the vascular function test was performed. The thoracic aortic ring of SD rats was mounted on a bath system. The effect of rosiglitazone on the contraction elicited by L-phenylephrine (PE) and potassium chloride (KCl) and the relaxation induced by acetylcholine (ACh) and sodium nitroprusside (SNP) were measured. To explore the mechanism, nitric oxide synthase (NOS) inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) was used and serum nitric oxide (NO) was measured. The results obtained were as follows: (1) Rosiglitazone reduced the level of SBP, serum insulin and improved insulin resistance in IRHRs. (2) The contractive responses of thoracic aortic rings to PE and KCl were enhanced and the relaxation response to ACh was depressed significantly in the HF group, and the effect was reversed by ROSI. (3) After pretreatment with L-NAME, the relaxation response to ACh was further impaired in the HF group, this effect was partly reversed by ROSI. (4) Sodium nitroprusside (SNP)-induced vasodilator responses did not differ significantly among the groups. (5) Aortic systolic and diastolic function of the control group was not affected markedly by ROSI. (6) Compared with the control group, serum nitric oxide was significantly reduced in the HF group, but after rosiglitazone treatment it was remarkably increased. These findings suggest that ROSI can improve aortic diastolic function of insulin resistant-hypertensive rats, the mechanism of this effect might be associated with an increase in nitric oxide mediated partly by NOS pathway, a decrease in the level of blood pressure, serum insulin and the improvement of insulin resistance.

Animals↗

PubMed2005

Sequence of a cDNA encoding turtle high mobility group 1 protein.

In order to understand sequence information about turtle HMG1 gene, a cDNA encoding HMG1 protein of the Chinese soft-shell turtle (Pelodiscus sinensis) was amplified by RT-PCR from kidney total RNA, and was cloned, sequenced and analyzed. The results revealed that the open reading frame (ORF) of turtle HMG1 cDNA is 606 bp long. The ORF codifies 202 amino acid residues, from which two DNA-binding domains and one polyacidic region are derived. The DNA-binding domains share higher amino acid identity with homologues sequences of chicken (96.5%) and mammalian (74%) than homologues sequence of rainbow trout (67%). The polyacidic region shows 84.6% amino acid homology with the equivalent region of chicken HMG1 cDNA. Turtle HMG1 protein contains 3 Cys residues located at completely conserved positions. Conservation in sequence and structure suggests that the functions of turtle HMG1 cDNA may be highly conserved during evolution. To our knowledge, this is the first report of HMG1 cDNA sequence in any reptilian.

Amino Acid Sequence↗