Search PubMed⌕ Search

Biomedical subjects

J Gao

Publications and source records attributed to J Gao.

At least 325 records · Page 18Linked to original sources
PubMed1997

Focal microcirculation disorder induced by photochemical reaction in the guinea pig cochlea.

A small region of microcirculation disorder in the cochlea of the guinea pig could be induced by a photochemical reaction. Photoillumination to the cochlea was done after systemic infusion of Rose Bengal (RB). The lateral wall of the second or third turn of the cochlea was illuminated for 10 min with a 1 mm diameter focused green light supplied by a xenon lamp. Degeneration of the stria vascularis (SV) was observed by a scanning electron microscope at 60-300 min after illumination. The range of length of degenerated area in the SV was from 111 to 1800 microns, with a mean of 760 microns. The organ of Corti along the illuminated lesion of the SV was well preserved in all animals at 60-300 min. In contrast, degeneration of sensory hair cells and scar formation in the SV were observed in the focal lesions of the three animals killed 1 week after illumination. The increase of diameter in the vessel of the SV from the radiating arteriole, the vessel of basilar membrane (VSBM) and limbus vessel (LVS) were observed in the illuminated area with diaminobenzidine (DAB) staining. These findings suggest that segmental microcirculation damage occurred in the SV and modiolus. In physiological studies, compound action potentials (CAP) were evaluated. Endocochlear potentials (EP) were also measured at the second turn under three different situations (groups A, B and C). A photochemically induced lesion was created at the site of EP measurement (group A), a site in the second turn 1 mm from the EP measurement site (group B) and a site in the third turn adjacent to the EP measurement site (group C). Threshold shift of CAP (up to 5.6 +/- 1.8 dB SPL) and reduction of EP (down to 11.4 +/- 10.7 mV) in the photochemically injured location were detected during about 15 min. EP did not recover to the predamaged level (79.9 +/- 3.7 mV) during 20 min. The morphological and physiological changes were not observed in the control group with illumination only. There were no significant decreases in EP values at the sites 1 mm from the lesion (group B) and at the inferior turn adjacent to the lesion (group C) compared to the marked decrease at the site of the photochemically induced lesion (group A). These findings suggest that CAP and EP are significantly affected by the interruption of segmental blood supply in the cochlea and remarkable decrease of EP occurs in the focal region of the guinea pig cochlea. We conclude that a localized blood circulation disorder induced by the photochemical reaction can make a focal lesion in guinea pig cochlea morphologically and physiologically.

Action Potentials↗
PubMed1997

Correct blue-light regulation of pea Lhcb genes in an Arabidopsis background.

Irradiation of etiolated Arabidopsis or pea, or dim-red-light-grown pea seedling with a single, short (under 10 s) pulse of blue light (threshold at 0.1 mumol/m2) is sufficient to induce the expression of specific members of the Lhcb gene family including the pea Lhcb1*4 gene and the Arabidopsis Lhcb1*3 gene. Other Lhcb genes, such as the pea Lhcb1*3 gene and the Arabidopsis Lhcb1*1 and 1*2 genes are unaffected by this blue-light treatment. Transgenic Arabidopsis bearing pea Lhcb1*3::Gus (beta-glucuronidase), pea Lhcb1*4::Gus or Arabidopsis Lhcb1*3::Gus constructs were used to determine if pea and Arabidopsis employ a similar mechanism to achieve blue-light induced Lhcb expression. Examination of the respective Gus expression patterns in white-light-grown seedlings indicates that the pea promoters are active and properly expressed in the Arabidopsis background. Irradiation of dark-grown Arabidopsis with a 20 s pulse of blue light with a total fluence of 100 mumol/m-2 results in expression of the pea Lhcb1*4::Gus (beta-glucuronidase) construct, but not of the pea Lhcb1*3::Gus construct indicating that the pea promoters respond correctly to blue light in the Arabidopsis background. Fluence-response, time-course and reciprocity characteristics for the blue-light-induced expression of the pea Lhcb1*4::Gus construct closely resemble those of the endogenous Arabidopsis Lhcb genes, confirming the proper interpretation of the Arabidopsis blue-light-signaling mechanism by the pea Lhcb1*4 promoter and suggesting that the signaling mechanisms in the two plants are very similar, if not identical. Fluence response data for the steady-state level of transcript derived from an Arabidopsis Lhcb1*3::Gus construct extending 200 bp upstream of the site of transcription indicate that the blue light responsive elements(s) are contained within this 200 bp region.

Arabidopsis↗
PubMed1997

Low dietary fiber and high protein intakes associated with newly diagnosed diabetes in a remote aboriginal community.

The high prevalence of diabetes mellitus in North American aboriginal populations may be due to recent changes in lifestyle, including the adoption of a high-fat, low-fiber diet. To determine whether fat or fiber intakes were associated with new cases of diabetes, we studied 72% (728/1018) of residents aged > 9 y from a remote aboriginal community in northern Ontario using the 75-g oral-glucose-tolerance test and 24-h dietary recall. The mean fat intake of this population (36% of energy) was typical for North America, but fiber intake (1.2 g/MJ) was very low. Logistic-regression analysis, adjusted for age, sex, and body mass index, showed that a 1-SD increase in fiber intake reduced the risk of having diabetes by 39% (P = 0.026) whereas the same increase in protein intake increased the risk by 38% (P = 0.027). There was no significant effect of energy, fat, starch, or simple sugars. These data support Trowell's original dietary-fiber hypothesis that "... dietary fiber depleted starchy foods are conducive to the development of diabetes mellitus in susceptible human genotypes."

Adolescent↗
PubMed1997

Effects of epinephrine on insulin-stimulated glucose uptake and GLUT-4 phosphorylation in muscle.

beta-Adrenergic stimulation has been reported to inhibit insulin-stimulated glucose transport in adipocytes. This effect has been attributed to a decrease in the intrinsic activity of the GLUT-4 isoform of the glucose transporter that is mediated by phosphorylation of GLUT-4. Early studies showed no inhibition of insulin-stimulated glucose transport by epinephrine in skeletal muscle. The purpose of this study was to determine the effect of epinephrine on GLUT-4 phosphorylation, and reevaluate the effect of beta-adrenergic stimulation on insulin-activated glucose transport, in skeletal muscle. We found that 1 microM epinephrine, which raised adenosine 3',5'-cyclic monophosphate approximately ninefold, resulted in GLUT-4 phosphorylation in rat skeletal muscle but had no inhibitory effect on insulin-stimulated 3-O-methyl-D-glucose (3-MG) transport. In contrast to 3-MG transport, the uptakes of 2-deoxyglucose and glucose were markedly inhibited by epinephrine treatment. This inhibitory effect was presumably mediated by stimulation of glycogenolysis, which resulted in an increase in glucose 6-phosphate concentration to levels known to severely inhibit hexokinase. We conclude that 1) beta-adrenergic stimulation decreases glucose uptake by raising glucose 6-phosphate concentration, thus inhibiting hexokinase, but does not inhibit insulin-stimulated glucose transport and 2) phosphorylation of GLUT-4 has no effect on glucose transport in skeletal muscle.

3-O-Methylglucose↗
PubMed1997

Prolactin receptor heterogeneity in bovine fetal and maternal tissues.

Study of diverse PRL actions at a variety of fetal and maternal targets during pregnancy is complicated by receptor heterogeneity and multiple ligands circulating at this time. In the present studies, we have examined PRL receptors at a variety of potential targets by reverse transcription-PCR and Western analysis. Bovine tissues contain two different transcripts for the PRL receptor; the one that encodes a short form includes an additional 39 bases at a position identical to the deviation from the long form found in rodents and sheep. Western analyses of PRL receptors in microsomal fractions from various maternal and fetal tissues revealed considerable size heterogeneity. Collectively, the larger immunoreactive moieties (apparent Mr 100 kDa or greater) and the smaller species (47-55 kDa) correlated well with the relative abundance of the transcripts for the different forms of the receptor and varied considerably among tissues. N-Glycosylation was shown to be the major, but not the only, modification of both receptor forms when transiently transfected into COS-7 and END-6.2 cells. Much of the short form could be reduced to the mobility predicted from the complementary DNA by culture with tunicamycin; this was not true of the long form, suggesting modifications specific for its cytoplasmic domain. Differences in the pattern of immunoreactive species in the COS-7 and END-6.2 cells are consistent with cell-specific modifications. The ability of these receptor forms to mediate a transcriptional response to PRL and its placental relative, placental lactogen, was evaluated with a PRL response element inserted upstream from a thymidine kinase promoter/reporter gene construct transiently transfected into CHO-K1 cells. Both hormones were able to stimulate reporter gene expression through the long form, but not the short form, of the receptor. These studies will facilitate examination of tissue-specific actions of PRL and related hormones during pregnancy.

Amino Acid Sequence↗
PubMed1997

Progesterone receptor (PR) inhibits expression of insulin-like growth factor-binding protein-1 (IGFBP-1) in human endometrial cell line HEC-1B: characterization of the inhibitory effect of PR on the distal promoter region of the IGFBP-1 gene.

Progestin has been shown to have both stimulatory and inhibitory effects on the expression of insulin-like growth factor binding protein-1 (IGFBP-1) in human endometrial cells. In this study, progestin was found to reduce levels of secreted IGFBP-1 and IGFBP-1 messenger RNA and IGFBP-1 promoter activity after stably transfecting a progesterone receptor (PR; B form) expression vector into HEC-1B cells. Deletion analysis of the IGFBP-1 promoter revealed that PR specifically inhibited promoter activity derived from a 59-bp distal BsaHI/RsaI fragment. It was concluded that PR inhibited the promoter activity through protein-protein interactions based on the facts that 1) no progesterone-responsive element was revealed by a series block mutation in the BsaHI/RsaI fragment; 2) PR bound by the antiprogesterone ZK98299 inhibited IGFBP-1 promoter activity; 3) a DNA-binding mutant of PR inhibited the IGFBP-1 promoter activity; and 4) in an in vivo competition assay, the DNA-binding domain of PR did not release the inhibitory effect of intact PR. Analysis of PR deletion mutants indicated that both transcriptional activation domains of PR (TAF-1 and TAF-2) were involved in the inhibition of IGFBP-1 expression. Thus, our data may explain the superinduction of IGFBP-1 in human endometrial cells after progestin withdrawal or progestin replacement with antiprogestin.

Base Sequence↗
PubMed1997

Neuron degeneration induced by verapamil and attenuated by EGb761.

Calcium channel blockers are used as neuroprotective agents, as glutamate antagonists. However, it has been found that calcium channel blockers may compromise neuronal survival after long-term exposure. To explore the mechanisms of the toxicity of calcium channel blockers on neurons, we studied the morphological characteristics and biochemical changes of cultured cortical neurons treated with verapamil, a calcium channel blocker. We now report that cerebral cortical cultures exposed to verapamil for 48 h undergo neuronal degeneration in both concentration-dependent and time-dependent fashion, possibly partially through the activation of apoptosis. On the other hand, it was found that Ginkgo biloba extract (EGb761) attenuated verapamil-induced neuronal injury, suggesting the possibility of using verapamil combined with EGb761 clinically. Furthermore, both B-50 immunoactivity (BIA) and the concentration of intracellular calcium in single neurons ([Ca2+]i) decreased after a 48-h exposure to verapamil, suggesting that the mechanisms of verapamil-induced degeneration may be associated with the disruption of intracellular calcium homeostasis and the inhibition of normal axonal elongation.

Animals↗
PubMed1997

The prevalence of NIDDM and associated risk factors in native Canadians.

OBJECTIVE: To determine the true prevalence of impaired glucose tolerance (IGT), NIDDM, and associated risk factors by age and sex in an isolated native community. RESEARCH DESIGN AND METHODS: A community-wide prevalence survey using a 75-g oral glucose tolerance test (OGTT) was undertaken in the remote native reserve of Sandy Lake, Ontario, Canada. Measurements for obesity included waist-to-hip circumference, BMI, and percentage body fat. RESULTS: A total of 728 individuals were enrolled, representing a community participation rate of 72%. The overall crude prevalence of NIDDM was 17.2% (18.1% females and 16.0% males) and increased to 26.1% overall (28.0% females and 24.2% males) when age-standardized. The prevalence of IGT was higher in females compared with males (age-standardized prevalence of 19.8 vs. 7.1%, respectively). Females had a higher prevalence of obesity, IGT, and NIDDM occurring at younger ages. Measures of obesity and fasting insulin levels were significantly associated with NIDDM in the 18-49 age-group. CONCLUSIONS: The prevalence rates of NIDDM in this study population are the highest reported to date in a Canadian native population and among the highest reported in the world. Females appear to be at much higher risk of developing obesity, IGT, and NIDDM and at a younger age. Due to the high prevalence rates of IGT and NIDDM in this young population, there is urgent need to develop culturally appropriate community-based public health intervention programs before the long-term complications of diabetes have a devastating effect on the residents.

Adolescent↗
PubMed1997

Antagonistic effects of extract from leaves of ginkgo biloba on glutamate neurotoxicity.

AIM: To determine whether the extract of leaves of Ginkgo biloba L (EGb) and several active constituents of EGb have protective effects against glutamate (Glu)-induced neuronal damage. METHODS: Microscopy and image analysis of nucleus areas in the arcuate nuclei (AN) of mice were made. The neuronal viability in primary cultures from mouse cerebral cortex was assessed using MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide] staining and the intracellular free calcium concentration ([Ca2+]i) of single neuron was measured using Fura-2. RESULTS: EGb (2.5 mg.L-1) and its constituent ginkgolide B (Gin B, 2 mg.L-1) protected the neuronal viability against Glu-induced injury, and prevented the Glu-induced elevation in [Ca2+]i. EGb (3-10 mg.kg-1) attenuated the decrease of nucleus areas in arcuate nuclei induced by Glu (1 g.kg-1, s.c.). CONCLUSION: EGb and Gin B prevent neurons from Glu neurotoxicity through reduction of the rise in [Ca2+]i.

Animals↗
PubMed1997

[The Chinese total diet study in 1992--chemical contaminants. (II) Different age-sex groups].

The total diet study on various age-sex groups and the comparison of two seasons (spring and autumn) in adult male were conducted in the second Chinese Total Diet Study in 1992-1993. The dietary pattern, dietary intake of heavy metals and other harmful elements and radionuclides were studied in 4 age-sex groups in 4 provinces and cities, i.e. Hebei, Shanxi, Hubei and Shanghai. The contamination of lead in diet was the most outstanding finding. The intake of lead in 2-7 years old exceeded 18.9% of the ADI. The contamination of cadmium and mercury in diet were low, and the dietary intake were 24% and 35% of the ADI respectively. The dietary intakes of aluminium in the two young groups exceeded about 8% of the ADI. The intake of dietary fluoride in the two young groups were a little too low, and it was adequate in the adult groups. The overall dietary intake of radionuclides in the 4 age-sex groups was only 36% of ALI. The intakes of man-made radionuclides, 90Sr and 137Cs were all below 1% of ALI. The comparisons of two seasons (spring and autumn) showed that the overall intakes of radionuclides were higher in autumn than in spring. The intake of 210Pb was 3-4 times in autumn than in spring.

Adolescent↗
PubMed1997

[The Chinese total diet study in 1992--macro elements and trace elements].

Ten macro elements and trace elements were directly determined in the 1992 total diet study conducted in four districts of China from north to south. The intake of these elements was evaluated. The levels of intake for seasonal variation and for different age groups were reported. The results showed that the intakes of Ca, P, K, Mg, Zn, Se and Cu were low in children. The intake of Ca, P and Zn was insufficient for adults. The intakes of other seven elements reached or approached their RDA levels, but there were big differences among the 4 districts. The relationships between intakes of Ca/P and Na/K as well as Fe and Cu and iron difficiency anemia were discussed.

Adolescent↗
PubMed1997

[The Chinese Total Diet Study in 1992--chemical contaminants (I). Comparison between different areas].

The second Chinese total diet study was carried in 1992-1993. This paper describes the overall design and method of study, and dietary intake of heavy metals and other harmful elements, and pesticides. The average lead and mercury intakes were lower than those in 1990, and the dietary intake of cadmium was higher than that in 1990. The intake of aluminium and fluoride were reported for the first time. The levels of some contaminants in individual areas exceeded the tolerance limit. For example, mercury in North 1 exceeded 95.7% in legumes; fluoride in cereals, except South 2, exceeded 11.9%-95.3%. The intake of HCH was close to that in 1990, and the intake of DDT was lower than that in 1990. Seven out of the fifteen organophosphorus pesticides were detected in this study, although the dietary intakes were low, only accounted for about/or below 1% of ADI.

Aluminum↗
PubMed1997

[Detection of mRNA expression of endothelin-1 in organs on severe burn rat model with in situ hybridization technique].

After the dynamic observation of postburn endothelin changes in plasma on severe burn rat model, we detected ET-1 mRNA expression and cell localization in some organs such as heart, lung, liver and kidney with in situ hybridization technique. We that endothelin concentration in plasma rapidly increased postburn (it reached its climax at 6th hour and maintained fairly high level even at 24th hour postburn). Meanwhile in situ hybridization indicated that ET-1 mRNA expression intensity and number of positive cells rapidly increased postburn. The expression climaxes of which appeared decreasing in turn from kidney, liver, lung to heart and the types of positive cells increased. This may due to the endothelin's functions of contracting blood vessels and regulating the redistribution of blood flow and be helpful for guaranteeing blood perfusion of important organs under shock state, but the overexpression of ET-1 mRNA may make the ischemic and anoxic damages to organs more severe.

Animals↗
PubMed1997

[Forty six cases of application of free femoris forelateralis flap in trauma].

In serious scar or chronic ulcer caused by burn or trauma, skin graft can not be survival and the local flap can not be found in these cases. Also skin grafts can not improve function of these places. Free flap transplantation should be used in these cases. Femoris forelateralis flap has some advantages. It is hidden from view and there is no effect after it is taken. It has constant blood vessels which are easy anastomosed. So the flap is more widely used. Forty-six cases were given femoris forelateralis flaps (hand burn scar deformity 15 cases, foot scar 10, forearm or leg scar or tissue defect 8, leg or foot chronic ulcer 8, face or neck tissue defect or serious scar 8). Forty-five cases (97.8%), were survival. Only one case had necrosis. The key of survival is choice of the operative indication, excellent anastomosis technique, good fixation postoperatively, care observation, and timely handling. In vasculitis or phlebitis ulcer, the vessel condition is bad. In old people, especial with heart or vessel diseases, condition is also bad. We shoule be careful in these situations.

Adolescent↗
PubMed1997

Chinese dietary composition and intakes of elements and radionuclides by ingestion.

As update and complement of Chinese Total Diet Study in 1990, a renewing study was conducted during 1992-1993 according to regulated procedure. Contents of 32 elements, including 19 newly determined, in 12 categories of food from 12 provinces were analyzed by NAA or AAS technique and the daily intakes of Chinese adult man were estimated and hygienically evaluated. Meanwhile, a typical survey on dietary composition and intake for difference among 4 age groups and between Spring and Autumn was surveyed too. The results provide important basis for decision for further improvement of Chinese diet from hygienic view point and compilation of physiological characteristics of Chinese Reference Man. At the end of this article, the estimated nationwide average intakes for adult man are compared with those for current ICRP Reference Man.

Adolescent↗
PubMed1997

[The clinical analysis of eosinophil infiltration in human squamous cell carcinoma of buccal mucosa].

Tumor-associated tissue eosinophils (TATE) is a host's defensive reaction to tumor. In this study, authors examined the eosinophil of 40 squamous cell carcinomas of buccal mucosa. Infiltration of the primary tumor by eosinophil was found to have marked prognostic significance. High-grade TATE was associated with the absence of head and neck lymphonode's metastasis (P < 0.05). There was a statistical significance (P < 0.05) that high-grade TATE was a favorable prognostic indicator for squamous cell carcinoma of the buccal mucosa. Authors concluded that quantitative assessment of eosinophils was one of the most important aspects of the microscopic evaluation of this human carcinoma.

Adult↗
PubMed1997

[Maxillofacial injury: clinical analysis of 284 cases].

Maxillofacial injury is common in war or in the routine life. Always accompanying trauma of other sites of the body, it has its own characters and leads to serious outcome. This article made a clinical analysis of 284 cases of maxillofacial injury from following aspects: onset of wounded, characters and chief complications of maxillofacial soft and hard tissues injury and foreign bodies left in place. The authors also discussed their experiences at emergency management.

Accidents, Traffic↗