Biomedical subjects

S Bao

Publications and source records attributed to S Bao.

113 records · Page 7Linked to original sources

PubMed1986

[Effects of 4-(o-benzylphenoxy)-N-methylbutylamine hydrochloride (bifemelane) on ischemic cerebral edema induced in the gerbil].

Effects of the new chemical agent, bifemelane, on ischemic cerebral edema were studied in 70 mongolian gerbils. Five different doses of bifemelane (0.2-25.0 mg/kg) as well as saline were administered intraperitoneally in 6 groups of animals (n = 46), and 30 min afterward both common carotid arteries were occluded. The brain was removed 90 min after the occlusion, and the cerebral water content (CWC) in the bifemelane treated groups and the controls was compared. To assess hemodynamic effects of bifemelane, regional cerebral blood flow (rCBF) was also measured in 24 animals using hydrogen clearance techniques. The CWC in the saline-treated controls (79.9 +/- 0.4%) was significantly increased compared to the normal values (78.4 +/- 0.3%). The CWC in the groups receiving 1 mg/kg, 5 mg/kg and 10 mg/kg of bifemelane showed 79.3 +/- 0.3%, 79.5 +/- 0.2% and 78.9 +/- 0.3%, which were significantly lower than the controls (p less than 0.005, p less than 0.02, p less than 0.001). Thus, bifemelane reduced a development of ischemic cerebral edema in a dose-dependent manner. The rCBF in the bifemelane groups and the controls measured before the drug administration was the same ranging within 35.0-37.0 ml/100 g brain/min. The administration of bifemelane produced small rCBF increase. After the carotid artery occlusion, rCBF in all control animals decreased below 6.0 ml/100 g brain/min, the critical level for cellular ion-pump function. The majority of bifemelane-treated animals also showed a similar flow reduction. However, in 33% of animals receiving 10 mg/kg or 25 mg/kg of bifemelane, rCBF was maintained above this critical level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMedDate not supplied

Antigen delivery strategies for mucosal vaccines.

Progress towards effective vaccines to control internal parasites, especially those affecting mucosal compartments, has been inhibited by the combined problems of the antigenic complexity of parasites and the lack of understanding of the host response. However, the accumulation of information regarding regulation of mucosal immunity has enabled a reappraisal of vaccination options to provide appropriate mucosal effector responses. The pivotal role of T cell influences, and in particular the contribution of cytokine signals, has been clearly established from in vitro studies, but data emerging from our laboratories provide evidence for these effects in vivo. We have demonstrated the role of T cells in determining the outcome of an intestinal response and propose a role for local Th2 cytokine production in this regard. To support this proposition, the distribution of cytokine mRNA has been determined by in situ hybridisation techniques in normal and parasitised animals. Further, we have shown that in the absence of Th2 cytokines (using gene knockout animals) mucosal responses are grossly deficient; we have also shown that this defect can be overcome by vector-directed gene therapy. These studies have indicated that new mucosal immunisation opportunities exist by combining traditional immunisation approaches with strategies to upregulate local cytokine production. However, the success of these new strategies will depend on selection of highly immunogenic subunit antigens, coupled with techniques for cytokine manipulation and delivery with appropriate adjuvant/vehicle formulations. This paper reviews delivery technologies available to chaperone labile antigenic and genetic material to appropriate sites for mucosal stimulation after systemic or oral administration.

Animals↗

PubMedDate not supplied

Impaired eye-blink conditioning in waggler, a mutant mouse with cerebellar BDNF deficiency.

In addition to their trophic functions, neurotrophins are also implicated in synaptic modulation and learning and memory. Although gene knockout techniques have been used widely in studying the roles of neurotrophins at molecular and cellular levels, behavioral studies using neurotrophin knockouts are limited by the early-onset lethality and various sensory deficits associated with the gene knockout mice. In the present study, we found that in a spontaneous mutant mouse, waggler, the expression of brain-derived neurotrophic factor (BDNF) was selectively absent in the cerebellar granule cells. The cytoarchitecture of the waggler cerebellum appeared to be normal at the light microscope level. The mutant mice exhibited no sensory deficits to auditory stimuli or heat-induced pain. However, they were massively impaired in classic eye-blink conditioning. These results suggest that BDNF may have a role in normal cerebellar neuronal function, which, in turn, is essential for classic eye-blink conditioning.

Animals↗

PubMedDate not supplied

Transgenic brain-derived neurotrophic factor modulates a developing cerebellar inhibitory synapse.

Brain-derived neurotrophic factor (BDNF) has been shown to promote synapse formation and maturation in neurons of many brain regions, including inhibitory synapses. In the cerebellum, the Golgi cell-granule cell GABAergic synaptic responses undergo developmental transition from slow-decaying to fast-decaying kinetics, which parallels a developmental increase of GABA(A) receptor alpha6 subunit expression in the cerebellar granule cells. In culture, BDNF accelerates the expression of GABA(A) receptor alpha6 subunit expression in granule cells. Here we examined synaptic GABA(A) response kinetics in BDNF transgenic mice. The mutant mouse, which carries a BDNF transgene driven by a beta-actin promoter, overexpresses BDNF (two- to fivefold increase compared with wild types) in all brain regions. Recordings of the spontaneous GABA(A) responses indicate that the decay time constant of the GABAergic responses decreases during early postnatal development; this transition is accelerated in the BDNF transgenic mouse. The amplitude of the spontaneous GABA(A) responses was also larger in the transgenic mouse than in the wild-type mouse. However, the frequency of the spontaneous GABA(A) responses were not different between the two groups. Our results suggest that BDNF may modulate GABAergic synapse maturation in the cerebellum.

Aging↗

PubMedDate not supplied

Brain nitric oxide synthase expression is enhanced in the human cervix in labor.

OBJECTIVES: To determine whether brain nitric oxide synthase (bNOS) is expressed in human cervix, define its localization, and examine the possibility that it contributes to the nitric oxide (NO) pool and has a role in human cervical ripening. METHODS: Human cervical biopsy tissues were collected from four groups: (1) nonpregnant patients, (2) term nonlabor (cesarean delivery) patients, (3) term labor patients with cesarean deliveries, and (4) term labor patients (vaginal delivery). The mRNA expression was assessed using reverse-transcribed polymerase chain reaction and in situ hybridization. The protein expression was determined using Western blot and its localization was shown using immunostaining. RESULTS: Both bNOS mRNA and protein are present in human cervical tissue. They were localized to stroma cells and epithelial cells by in situ hybridization and immunostaining. bNOS protein expression in the labor group was significantly higher than in the nonlabor group (P <.05). CONCLUSION: bNOS is expressed in the human cervix and enhanced expression is observed in labor, suggesting its possible role in contributing to the NO pool in the human cervix, in cervical ripening, and in labor.

Blotting, Western↗