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Biomedical subjects

T Li

Publications and source records attributed to T Li.

At least 523 records · Page 29Linked to original sources
PubMed1992

[Role of sulfhydryl compounds in the oxygen radical induced injury of isolated gastric mucosal cells].

Gastric mucosal cells were separated by pronase-EDTA method and cultured. The cellular injury was produced by oxygen radicals provided by xanthine oxidase(XO)-xanthine(X) system. When the cells were subjected to the action of XO-X system, the cellular viability was decreased and leakage of lactate dehydrogenase (LDH) from the cells was significantly increased. In addition, the cellular contents of nonprotein sulfhydryls (NPSH) and protein sulfhydryls (PSH) were decreased. When the intracellular sulfhydryl content was decreased by N-ethylmaleimide (NEM, a depletor of endogenous sulfhydryls), the cell mortality and LDH leakage were increased in a time-dependent and dose-dependent manner. If glutathione or cysteamine (compounds containing-SH) was administered into the media, the cellular injury induced by XO-X system was notably inhibited, also in a dose-dependent manner. The above results suggest that sulfhydryls may play an important role in the cell defending mechanism against injury of gastric mucosal cells by oxygen radicals.

Animals↗
PubMed1992

[Study on the meiotic mapping and functions of another new osmotic-sensitive gene-osm3 in Saccharomyces cerevisiae].

Another recessive nuclear gene mutation of Sacchromyces cerevisiae, osm3, which causes growth inhibition on hypertonic media, has been mapped on the chromosome II by tetrad analysis. Its second-division segregation frequency is about 51.01%, and the map distances between osm3 and the centromere of chromosome II is about 25.51 centimorgans and it is approximately 45 centimorgans far gene gall. The studies on the reverse mutation of osm3 indicated that this osmotic-sensitivity arises from a missense or nonsense mutation in OSM3 locus. The response of yeast to osmotic stress and the mechanism of osm3 gene function were investigated. The results indicated that high intracellular glycerol content is necessary for yeast to grow in hypertonic media; The gene product of osm3 is probably relative to the process of glycerol transportation. Finally, the effect of osmotic stress on fermentability was also discussed.

Chromosome Mapping↗
PubMed1992

Relation between inhibition of renal angiotensin II production and hemodynamic effect of captopril in anesthetized rabbit.

OBJECTIVE: This study was conducted in order to determine the relation between the renal hemodynamic effect of an angiotensin converting enzyme (ACE) inhibitor and its effect upon plasma angiotensin II levels in the rabbit. DESIGN: The effect of captopril upon arterial and renal venous plasma angiotensin II concentrations was assumed to reflect the systemic and renal actions of ACE inhibition. METHODS: Systemic blood pressure, renal blood flow (RBF), and arterial and renal venous plasma concentrations of angiotensin II and angiotensin I were measured in five groups of anesthetized rabbits; groups Ia and Ib consisted of sodium-replete and group II sodium-deplete rabbits in which captopril was administered in a maximal ACE inhibiting dose of 2 mg/kg, intravenously, followed by an intra-arterial (group Ia) or an intravenous (group Ib) infusion of 1 mg/kg per h; group III consisted of sodium-replete rabbits given a low captopril dose of 10 micrograms/kg per min, intra-arterially; and group IV represented control levels. In a separate group of rabbits (group V) the effects of a low dose of 10 micrograms/kg per min captopril in the presence of the angiotensin II antagonist DuP 753 were studied. RESULTS: The high dose of captopril decreased blood pressure and increased RBF in both sodium-replete and sodium-deplete rabbits. Arterial and renal venous angiotensin II levels were low in group Ia compared with groups Ib and II; however, in all three groups angiotensin II levels were markedly decreased during high-dose captopril administration. The low dose of captopril caused approximately the same increase in RBF, despite no change in angiotensin II levels. Angiotensin I concentrations tended to increase during high-dose captopril administration due to blockade of negative feedback of renin release. A time trend did not account for the results, since blood pressure, RBF and angiotensin II were stable over a 1-h period in control experiments. CONCLUSION: These results suggest that different pools of renal angiotensin II may exist, and that a small critically located pool, possibly in the endothelium, may be important in renal vascular control.

Angiotensin I↗
PubMed1992

[Thin layer chromatography for identification of 9 species of traditional Chinese medicine in baihe gujin tang granules].

Baihe Gujin Tang granules are mainly composed of nine species of traditional Chinese medicine and other admixtures, so the composition is very complex. In order to confirm the presence of each traditional Chinese medicine in the preparation, a thin layer chromatographic method was developed successfully for analysis of Scrophulariae, Platycodon, Paeoniae and Glycyrrhizae.

Chromatography, Thin Layer↗
PubMed1992

Vasoconstrictor and vasodilator effects of serotonin in the isolated rabbit kidney.

The renal vascular effects of serotonin (5-HT) in vivo vary among preparations, which may reflect that this autacoid can modulate the vascular response to certain spasmogens. We investigated this phenomenon in the isolated rabbit kidney perfused under constant flow (5 ml/min) with Krebs-bicarbonate buffer. Dose-response experiments to 5-HT were conducted before and during an infusion of half-maximal effective doses of norepinephrine (NE), phenylephrine (PE) or endothelin-1 (ET-1). Each infusion was varied to raise the perfusion pressure (PP) from a baseline of 18-28 mm Hg to a level of 80-100 mm Hg. In the absence of infused NE, PE or ET-1, bolus injections of 5-HT had little or no effect. However, in the presence of NE, 5-HT injections of 20 pmol to 20 nmol caused a dose-dependent increase in PP; higher doses (0.4-4 mumol) of 5-HT caused a dose-dependent decrease in PP. Similar results with 5-HT were obtained in the presence of an infusion of PE. However, in the presence of ET-1, 5-HT injections elicited only a modest increase in PP, which was significantly less than the increase in the presence of NE; and they did not have the vasodilator effect on the isolated perfused kidney. Histamine injections only increased but did not decrease the PP in PE-precontracted renal vasculature. Infusion of 5-HT at 20 nmol/min potentiated the dose-dependent effect of NE on PP, but 5-HT infusion of 1 mumol/min attenuated the effect of NE on PP.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[A new virus of rabbit. III. Study on morphological superstructure and antigenicity of rabbit hemorrhagic disease virus (RHDV)].

In the spring 1986, an acute infectious disease occurred in Wuhan Second Producing Medical Manufactory, and the rabbit almost died. We tested the mortal symptom and confirmed rabbit Hemorrhagic Disease (RHD) as same as Huang Yinyao report. Hubei Traditional Chinese Medicine Institute appear this RHD also. After we purified virus of above two source by low speed, high speed and sucrose density gradient centrifugation, they can react with antiserum of RHDV from Nanjing Agricultural University in agar gel immunodiffusion tests. These results proved that they belong to the same serotype. Data indicate RHDV have difference morphological superstructure, viral polypeptides and especially RHDV can't react with antiserum of standard Parvovirus of rabbit and so on, so we suggest RHDV is a new virus.

Animals↗
PubMed1992

A study on optimum load for physical work.

Five healthy men were chosen as experimental subjects and were divided into groups at random. The subjects walked with a load in a shoulder-waist-back manner on the treadmill at the speed of 5, 7 and 9 km h-1. The parameters measured were as follows: oxygen expenditure, energy consumption, heart rate and self appraisal. Based on the experimental results and analysis of multiple regression, the authors suggested that physical loading should not exceed 25 kg (i.e. roughly equal to 39% of average body weight of male Chinese), when the walking speed was at 5 km h-1. The suitable loading at physical work would be 20 kg (i.e. equal to 31% of the average body weight of male Chinese).

Adult↗
PubMed1992

Regional differences in the effects of septic shock on vascular reactivity in the rabbit.

Experiments were performed to investigate the vascular reactivity in both large and resistance artery preparations from an animal model of septic shock. New Zealand White rabbits were injected with a priming dose of Escherichia coli lipopolysaccharide (LPS), 15 micrograms/kg i.v., 18 hr before an i.v. dose of 200 to 2000 micrograms/kg under pentobarbital anesthesia. The second LPS challenge dropped mean blood pressure from 79 +/- 4 to 27 +/- 5 mm Hg in approximately 1 hr. At this time animals were sacrificed with the central ear arteries and kidneys being isolated for alignment in a Krebs-bicarbonate buffer perfusion apparatus to monitor perfusion pressure under constant flow conditions. Individual dose-response curves (DRCs) for norepinephrine (NE) and histamine were performed to assess contractile function. For examining vascular relaxant function, DRCs for methacholine (MC) and nitroprusside (NP) were conducted during a submaximal infusion of NE. The DRCs to NE and histamine were shifted to the right by 2- and 2.7-fold, respectively, in isolated ear artery preparations from LPS-treated vs. vehicle-treated animals. There was no difference in contractile function (using NE) in the two groups of perfused kidneys. The relaxation DRCs to MC were similar in the ear artery preparations from the two treatment groups whereas, in isolated kidneys, the relaxation to MC was significantly attenuated, by an average of 26 +/- 2% at each of six doses, in preparations from LPS-treated animals. The relaxation to NP was similar between the LPS- and vehicle-treated animals in the ear artery and kidney preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Ultrasonic diagnosis of liver hydatid disease].

The experience of the ultrasonic diagnosis of intrahepatic secondary changes in 36 cases with liver hydatidosis was reported. The ultrasonograms were classified into five types: I. separated internal capsule, II. disruptive internal capsule; III. mixed echo; IV. thick-wall calcification; and V. consolidation. We studied the ultrasonogram character of the five types, and considered that the occurrence of type I, type II, and type IV resulted from single cyst pattern, while type III and type V resulted from multiple cyst pattern. Analysing the pathological foundation of the ultrasonogram changes can offer clinicians a reliable basis for choosing a treatment method.

Adolescent↗
PubMed1991

Effects of reheating on the accuracy of addition silicone putty-wash impressions.

The effect of the relatively high thermal contraction of addition silicones (polyvinylsiloxane) on the accuracy of stone casts was evaluated using the putty/wash relining impression technique and acrylic resin trays. Impressions were made at 37 degrees C and were divided into two groups. One group was poured at room temperature (22 degrees +/- 2 degrees C) and another group was reheated to 37 degrees C before pouring. Measurement of the dimensional changes failed to reveal improved accuracy of the stone casts poured at the same temperature as that reached during impression making. On the basis of this limited sample, it can be concluded that reheating the impression using the putty/wash relining technique did not improve the accuracy of the stone cast.

Acrylic Resins↗
PubMed1991

Marginal accuracy of complete crowns made from alternative casting alloys.

The marginal accuracy of complete cast crowns made from five alternative casting alloys was measured and compared with that of crowns made from the traditional type III high-gold alloy. The alternative alloys studied were low-gold-palladium, high palladium, silver-palladium, nickel-chrome-molybdenum, and copper-aluminum. The findings indicated that Ag-Pd alloy crowns exhibited the best marginal accuracy among the alternative alloys tested. However, their marginal discrepancy value was still slightly higher than that of crowns made of type III high-gold alloy. Conversely, Ni-Cr-Mo alloy crowns exhibited the poorest marginal accuracy.

Cementation↗
PubMed1991

Biochemical and serological characterization of Carnobacterium spp. isolated from farmed and natural populations of striped bass and catfish.

A comparative analysis of the phenotypic and serological properties of Carnobacterium strains associated with mortalities of cultured striped bass and channel catfish and the properties of isolates from wild brown bullhead catfish in the Chesapeake Bay area in Maryland was conducted. All of the strains were gram-positive, facultatively anaerobic, nonmotile, non-spore-forming rods occurring singly or in short chains. They did not produce cytochrome oxidase or catalase, did not reduce nitrate, failed to produce H2S, were unable to grow on acetate medium, and did not produce gas from glucose or gluconate. The temperature and salinity ranges for most of the strains were 10 to 37 degrees C and 0 to 6% NaCl, respectively. The strains all fermented mannitol and inulin and were arginine dihydrolase positive; these are typical characteristics of Carnobacterium piscicola. The carbohydrate fermentation pattern exhibited by all of the isolates with the API-50 CHL system was also very similar to that shown by C. piscicola. Acid was produced from ribose, glucose, fructose, mannose, mannitol, N-acetylglucosamine, amygdaline, arbutin, esculin, salicin, cellobiose, maltose, sucrose, trehalose, and gentiobiose. The Carnobacterium strains did not show proteolytic, lipolytic, amylolytic, or hemolytic activity. Eighteen drugs were tested; all strains proved to be resistant to chloramphenicol, gentamicin, kanamycin, streptomycin, trimethoprim, quinolones, and nitrofurans. The analysis of membrane proteins supported the phenotypic similarities, two main patterns were established, one shared by the striped bass isolates and the reference strain of C. piscicola and another shared by most of the catfish strains. However, the agglutination assays demonstrated that only one Carnobacterium strain from striped bass was serologically related to C. piscicola ATCC 35586.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Peplomycin-induced DNA repair synthesis in permeable mouse ascites sarcoma cells.

DNA repair synthesis induced in permeable mouse ascites sarcoma cells by peplomycin, an antitumor antibiotic, was studied. Mouse ascites sarcoma (SR-C3H/He) cells were permeabilized with a low concentration of Triton X-100 in an isotonic condition. Permeable cells were treated with an appropriate concentration of peplomycin to introduce single-strand breaks in permeable cell DNA. DNA repair synthesis in peplomycin-treated permeable cells was measured by incubating the cells with four deoxynucleoside triphosphates in an appropriate buffer system. The DNA repair synthesis was enhanced by ATP and NaCl at near physiological concentrations. More than 90% of DNA synthesis in the present system depended on the peplomycin-treatment. The repair nature of the DNA synthesis was confirmed by a BrdUMP density shift technique. The repair patches were largely completed and ligated in the presence of ATP. Analyses using selective inhibitors for DNA polymerases showed that both DNA polymerase Beta and aphidicolin-sensitive DNA polymerases (DNA polymerase alpha and/or delta) were involved in the repair DNA synthesis.

Animals↗
PubMed1991

A morphological study of primary pulmonary hypertension--an analysis of six autopsy cases.

Six typical autopsy cases of primary pulmonary hypertension are reported. The histopathological features were as follows: medial hypertrophy of the muscular pulmonary arteries, muscularization of arterioles, internal fibrosis and fibroelastosis of muscular pulmonary arteries with typical "onion-skin" configuration, fibrinoid necrosis of the media or necrotizing arteries of muscular pulmonary arteries, and formation of highly characteristic plexiform lesions and dilatation lesions. It is thought that the plexiform lesions seen in all six cases represent morphological changes resulting from pulmonary hypertension rather than congenital abnormalities or thromboembolism.

Adult↗