Search PubMed⌕ Search

Biomedical subjects

G Li

Publications and source records attributed to G Li.

At least 1,009 records · Page 56Linked to original sources
PubMed1990

[Effects of fu-mai mixture on oxygen consumption, PaO2 and pulmonary artery pressure of animals under hypoxia].

10% Fu-mai mixture has been used in anoxia mice per os 0.5 ml one time. The experimental results indicate that the tolerance to anoxia under low or normal pressures is increased and the oxygen consumption at 5th, 10th, 15th, 20th and 25th minute is reduced. Moreover, the decrease of PaO2 and increase of pulmonic pressure in acute anoxia rabbits can be inhibited by transfusing 2.5 ml of the mixture. The virulence is very slight.

Animals↗
PubMed1990

[Snail distribution and susceptible zones of schistosomiasis in endemic areas around Poyang Lake].

To understand the situation of snail distribution and to explore the criteria of susceptible zones of schisosomiasis in endemic areas around Poyang Lake, a total of 1,222,910 mu of marshland in lake regions were surveyed for three years from 1982 through 1984 by 400 skillful observers. This article reports the relation between mean density of infected snails and incidence of acute schistosomiasis in marshland. We divided all susceptible marshlands of Poyang Lake area into three types, and found that about one fourth of the area belongs to the first type of susceptible zones, i.e., with high risk to schistosomiasis infection. Longitudinal observation showed that the types of susceptible zones changed very little unless measures of schistosomiasis control were taken. The results of field study suggested that we should put stress of schistosomiasis control on the first type of susceptible marshlands of Poyang Lake in future.

Animals↗
PubMed1990

[Relation of serum growth hormone and estradiol levels and osteoporosis in postmenopausal women].

Serum GH, E2, FSH, LH levels, bone mass, serum alkaline phosphatase (AKP), calcium levels and urinary calcium/creatine ratio in 42 postmenopausal women were compared with those in 30 women of fertile age. In thirteen out of the postmenopausal women we also observed these parameters before and after treatment with diethylstilbestrol (DES). The postmenopausal women had significantly reduced serum GH (P less than 0.01) and E2 levels (P less than 0.001) and increased serum FSH(P less than 0.001), LH levels (P less than 0.001), and had lower bone mass (P less than 0.01). They also had increased serum AKP levels (P less than 0.05) and urinary calcium/creatine ratio(P less than 0.01). There were positive correlations between serum E2 and GH levels, between postmenopausal bone loss and serum E2, GH decline. The postmenopausal bone loss began early as menopause commenced. After treatment with DES in 13 postmenopausal women, we observed that GH significantly increased (P less than 0.01) and FSH, LH decreased (P less than 0.001), AKP decreased by 27.58% and urinary calcium/creatine ratio decreased by 43.94% (compared with that before treatment). Our results indicate that bone turnover increased after menopause and resorption exceeded formation. There is bone loss in early postmenopause. The postmenopausal bone loss is related to serum GH, E2 levels. Estrogen replacement therapy is necessary in postmenopausal women and it should be given as early as possible. After treatment with DES, increased serum GH levels, decreased AKP values (27.58%) and urinary calcium/creatine ratio (43.94%) suggest that estrogen may play a definite role in bone metabolism through increased GH.

Aged↗
PubMed1990

[Selection of optimum technological conditions for vinegar-processing of fresh rhizoma Corydalis].

The Total alkaloid contents of chloroform extracts and aqueous decoctions of different vinegar-processed samples of fresh Rhizoma Corydalis were determined and compared using orthogonal experimental design. Two optimum schemes suggested by the results are 1. If aqueous decoction is wanted, the fresh tuber Corydalis should be scalded by hot edible vinegar till the liquid has permeated to its center; 2. If total alkaloid extract is required for making Chinese traditional patent medicine, the fresh Rhizoma should be slightly scalded with edible vinegar which has been diluted with an equal volume of water.

Alkaloids↗
PubMed1990

Inhibitory effect of omeprazole on the metabolism of midazolam in vitro.

To examine the effect of omeprazole on the hepatic drug metabolizing enzyme system microsomes from rat and human liver samples were incubated with midazolam (CAS 59467-70-8) in the absence and presence of various concentrations of omeprazole (CAS 73590-58-6), its sulfone metabolite and for comparison also with cimetidine. In the extracted incubation mixtures unchanged midazolam, a-OH-midazolam, 4-OH-midazolam and di-OH-midazolam were analyzed by HPLC. In both species omeprazole (and its sulfone) inhibited the formation of all three oxidized metabolites of midazolam and the corresponding IC50-values (range 0.2-1.3 mmol/l for rat microsomes and 0.2-1.5 mmol/l for human microsomes) were comparable to cimetidine (range 0.05 to 3.8 mmol/l). These results indicate that the oxidative metabolism of midazolam can be inhibited in vitro by omeprazole (and/or its sulfone metabolite) and this interaction should be considered if both drugs are administered concomitantly in man.

Animals↗
PubMed1990

[Ultrastructural localization of Leishmania donovani antigen by immunogold labeling technique].

By using Lowicryl K4M, a kind of low temperature embedding resin, to embed promastigotes of Leishmania donovani at -30 degrees C, the protozoal structure was well preserved when visualized by electron microscope. We have determined the distribution of the promastigote antigen of human and canine isolates of Leishmania donovani from Sichuan using two monoclonal antibodies combined with biotinylated goat antimouse IgG and streptavidin/colloidal gold conjugates. The results showed that the antigen recognized by the protective monoclonal antibody 2H6-E3 was mainly distributed in the outer side of promastigote membrane of Leishmania donovani Sichuan canine isolate. According to the high density of localized gold particles this antigen might be abundant in the promastigote membrane. This result facilitates further research on the component, property and function of this antigen. Monoclonal antibody 1H7-C2-E7 recognized the promastigote antigen of both human and canine isolates of Leishmania donovani from Sichuan, suggesting that these two isolates might share a common antigen, and 1H7-C2-E7 antibody might be used to diagnose the leishmaniasis caused by these two isolates.

Animals↗
PubMed1990

[Observations on neuronal activity in frontal cortex and EMGs in monkeys during performing noxious and innocuous heat discrimination GO/NO-GO task].

To study the functional implication of neuronal responses in frontal cortex to noxious and innocuous heat stimuli, experiments were carried out on two monkeys (Macaca mulatta) during performing a delayed discrimination GO/NO-GO task. The animals were trained to hold a lever for at least 3 s in the response period when an innocuous heat stimulus had been applied to the forearm in the cue period, or release it within 1 s with a noxious one. After a criterion of 90% of correct responses in 3 successive days was reached, single neuronal activity was recorded from the frontal cortex along with EMGs from six muscles in both arms. Of 142 task-related neurons recorded, 87 (66.4%) were related to heat, 34 to visual, and 21 to both visual and heat stimuli. Among the heat-related neurons, 22 were responsive to noxious heat, 18 to innocuous heat, and 47 to both. Of the neurons responding to both noxious and innocuous heat stimuli, 4 neurons showed changes in discharge rates, depending on the type of stimuli. In most cases, muscular activities just appeared at the moment of lever pressing and/or releasing in m. extensor digitorium communis, m. flexor carpi ulnaris and m. flexor carpi radialis of the performing arm. No regular muscular activities appeared in other muscles and in other periods of the task. The result showed that the neuronal responses in frontal cortex elicited by heat stimuli in the cue period were not related directly to the initiation and modulation of behaviours.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Spin-label ESR studies of lipid-protein interactions in thylakoid membranes.

Lipid-protein interactions in thylakoid membranes, and in the subthylakoid membrane fractions containing either photosystem 1 or photosystem 2, have been studied by using spin-labeled analogues of the thylakoid membrane lipid components, monogalactosyldiacylglycerol, phosphatidylglycerol, and phosphatidylcholine. The electron spin resonance spectra of the spin-labeled lipids all consist of two components, one corresponding to the fluid lipid environment in the membranes and the other to the motionally restricted membrane lipids interacting directly with the integral membrane proteins. Spectral subtraction has been used to quantitate the fraction of the membrane lipids in contact with the membrane proteins and to determine the selectivity between the different lipid classes for the lipid-protein interaction. The fractions of motionally restricted lipid in the thylakoid membrane are 0.36, 0.39, and 0.53, for the spin-labeled monogalactosyldiacylglycerol, phosphatidylcholine, the phosphatidylglycerol, respectively. Spin-labeled monogalactosyldiacylglycerol exhibits very little preferential interaction over phosphatidylchline, which suggests that part of the role of monogalactosyldiacylglycerol in thylakoid membranes is structural, as is the case for phosphatidylcholine in mammalian membranes. Spin-labeled phosphatidylglycerol shows a preferential interaction over the corresponding monogalactosyldiacylglycerol and phosphatidylcholine analogues, in contrast to the common behavior of this lipid in mammalian systems. This pattern of lipid selectivity is preserved in both the photosystem 1 and photosystem 2 enriched subthylakoid membrane fractions.

Chemical Phenomena↗
PubMed1989

Mode of activation of bovine brain inositol 1,4,5-trisphosphate 3-kinase by calmodulin and calcium.

The effect of Ca2+ and calmodulin (CaM) on the activation of purified bovine brain Ins(1,4,5)P3 kinase was quantified and interpreted according to the model of sequential equilibria generally used for other calmodulin-stimulated systems. Two main conclusions can be drawn. (i) CaM.Ca3 and CaM.Ca4 together are the biologically active species in vitro, as is the case for the great majority of other calmodulin targets. (ii) These species bind in a non-co-operative way to the enzyme with an affinity constant of 8.23 x 10(9) M-1, i.e. approx 10-fold higher than for most calmodulin-activated target enzymes. The dose-response curve of the activation of Ins(1,4,5)P3 kinase by calmodulin is not significantly impaired by melittin and trifluoperazine, whereas under very similar assay conditions the half-maximal activation of bovine brain cyclic AMP phosphodiesterase requires over 30-50-fold higher concentrations of CaM when 1 microM melittin or 20 microM-trifluoperazine is present in the assay medium. Similarly, 1 microM of the anti-calmodulin peptides seminalplasmin and gramicidin S, as well as 20 microM of N-(6-aminohexyl)-5-chloro-1-naphthalene-sulphonamide (W7), do not inhibit the activation process. These data suggest that binding and activation of Ins(1,4,5)P3 kinase require surface sites of calmodulin which are different from those involved in the binding of most other target enzymes or of model peptides.

Animals↗
PubMed1989

Different requirements for protein kinase C activation and Ca2+-independent insulin secretion in response to guanine nucleotides. Endogenously generated diacylglycerol requires elevated Ca2+ for kinase C insertion into membranes.

Electrically permeabilized RINm5F cells were used to assess the factors required for activation of protein kinase C (PKC) and insulin secretion. PKC was activated either by phorbol 12-myristate 13-acetate (PMA) or by the generation of endogenous diacylglycerol in response to the nonhydrolyzable guanine nucleotide analog guanosine 5'-O-(thiotriphosphate) (GTP gamma S). As shown previously, both PMA and GTP gamma S elicit Ca2+-independent insulin secretion. This effect was mimicked by guanyl-5'-yl imidodiphosphate (Gpp(NH)p) but not by guanosine 5'-O-(3-fluorotriphosphate) and guanosine 5'-O-(3-phenyltriphosphate) possessing only one negative charge in the gamma-phosphate group. The action of PMA was mediated by PKC, since the agent caused both phosphorylation of specific protein substrates and association of the enzyme with cellular membranes. This translocation was independent of the Ca2+ concentration employed. In contrast, GTP gamma S only promoted association of PKC with membranes at 10(-6) and 10(-5) M Ca2+ and failed to alter significantly protein phosphorylation in the absence of Ca2+. Neither Gpp(NH)p, which stimulates insulin release, nor the other two GTP analogs, increased the proportion of PKC associated with membranes. To verify that the Ca2+-dependent effect of GTP gamma S on PKC is due to activation of phospholipase C, we measured the generation of diacylglycerol. GTP gamma S indeed stimulated diacylglycerol production in the leaky cells by about 50% at Ca2+ concentrations between 10(-7) and 10(-5) M, an effect which was almost abolished in the absence of Ca2+. Thus, at 10(-7) M Ca2+, the concentration found in resting intact cells, the generated diacylglycerol was not sufficient to cause PKC insertion into the membrane, demonstrating that both elevated Ca2+ and diacylglycerol are necessary for translocation to occur. It is concluded that while PKC activation by PMA elicits Ca2+-independent insulin secretion, the kinase seems not to mediate the stimulatory action of GTP analogs in the absence of Ca2+.

Animals↗
PubMed1989

Canine bone blood flow estimated with microspheres.

Blood flow rate in the periosteal and endosteal cortices of the diaphysis of long bones was determined in eight anesthetized adult dogs using the radioactively labeled microsphere method. The flow rate in endosteal and periosteal cortices is not significantly different unless the endosteal cortex contains cancellous bone from the medullary cavity. The highest flow rate is in the ulna, with 6.50 ml/min/100 g for the endosteal cortex and 5.15 ml/min/100 g for the periosteal cortex. The lowest flow rate is in the femur, with 2.89 ml/min/100 g for the endosteal cortex and 2.29 ml/min/100 g for the periosteal cortex. The results of this study indicate that variation of blood flow does exist between bones of dogs. However, the flow rates of individual bone on the left and right sides in the same dog are not significantly different. This indicates that the data are reproducible and reliable, and differences are not an inaccuracy of the radioactively labeled microsphere method. The results also demonstrate that there are no significant differences in bone blood flow as measured with small numbers (fewer than 400 microspheres per sample) and large numbers (more than 400 microspheres per sample) of microspheres. The adequate number of microspheres in each bone sample is 150-250. Therefore, a dose of 0.5 x 10(6) spheres/kg body weight can be sufficient.

Animals↗
PubMed1989

Lymphocyte predominant Hodgkin's disease of nodular subtype combined with pulmonary lymphoid infiltration and hypogammaglobulinaemia.

Two cases of lymphocyte predominant Hodgkin's disease of nodular subtype (HDNP) are reported. In contrast to classic cases of HDNP which often involve only one lymph node region and show no further symptoms, these two patients exhibited lymphoid infiltrates of the lung and hypogammaglobulinaemia. In patient 2 a monotypic immunoglobulin pattern (light chain kappa) was demonstrated in the L & H-, Hodgkin- and Sternberg-Reed cells. Both cases represent an uncommon variant of lymphocyte predominant Hodgkin's disease.

Adult↗
PubMed1989

An epidemiological survey of age-related dementia in an urban area of Beijing.

An epidemiological survey of age-related dementia among community residents of an urban of Beijing was conducted in 1986. Initial screening of 1331 subjects aged 60 and above was made using the Mini-Mental State Examination (MMSE) with a cutoff point of 17. All suspected cases of dementia and 5.5% of all others were then given a full clinical examination, with subjects being diagnosed and classified according to DSM-III criteria. The MMSE was found to have satisfactory sensitivity, although scores were significantly correlated with education. Prevalence rates of moderate and severe dementia were 1.28% for those aged 60 and above and 1.82% for those aged 65 and above. Rates for multi-infarct dementia were higher than those for primary degenerative dementia; females had higher rates than males and rates increased sharply with age. All the dementia cases were cared for in their own homes, by relatives. There is a need for increased knowledge and services for elderly people in the community.

Aged↗
PubMed1989

Growth of immortal simian virus 40 tsA-transformed human fibroblasts is temperature dependent.

Simian virus 40 (SV40)-mediated transformation of human fibroblasts offers an experimental system for studying both carcinogenesis and cellular aging, since such transformants show the typical features of altered cellular growth but still have a limited life span in culture and undergo senescence. We have previously demonstrated (D. S. Neufeld, S. Ripley, A. Henderson, and H. L. Ozer, Mol. Cell. Biol. 7:2794-2802, 1987) that transformants generated with origin-defective mutants of SV40 show an increased frequency of overcoming senescence and becoming immortal. To clarify further the role of large T antigen, we have generated immortalized transformants by using origin-defective mutants of SV40 encoding a heat-labile large T antigen (tsA58 transformants). At a temperature permissive for large-T-antigen function (35 degrees C), the cell line AR5 had properties resembling those of cell lines transformed with wild-type SV40. However, the AR5 cells were unable to proliferate or form colonies at temperatures restrictive for large-T-antigen function (39 degrees C), demonstrating a continuous need for large T antigen even in immortalized human fibroblasts. Such immortal temperature-dependent transformants should be useful cell lines for the identification of other cellular or viral gene products that induce cell proliferation in human cells.

Antigens, Polyomavirus Transforming↗
PubMed1989

Neurological and electroneuromyographic assessment of the adverse effects of acrylamide on occupationally exposed workers.

Seventy-one acrylamide workers and fifty-one unexposed referents were studied. Weak legs and numb hands and feet, preceded by skin peeling from the hands, were the early symptoms of the acrylamide workers; their early signs were impairment of vibration sensation in their toes and loss of ankle reflexes. Three cases had cerebellar involvement followed by polyneuropathy due to heavy exposure. Electroneuromyographic changes, including a decrease in the sensory action potential amplitude, neurogenic abnormalities in electromyography, and prolongation of the ankle tendon reflex latency, are of greater importance in the early detection of acrylamide neurotoxicity since they can precede the neuropathic symptoms and signs. The diagnostic criteria for occupational acrylamide intoxication of this study revealed three severe poisonings, six moderate poisonings, and 43 mild poisonings. The total prevalence of acrylamide poisoning was 73.2%. The prevention of dermal exposure to acrylamide should be emphasized.

Acrylamide↗