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Biomedical subjects

Z Yan

Publications and source records attributed to Z Yan.

At least 217 records · Page 12Linked to original sources
PubMed1993

[Histochemical studies on the glycoconjugates of experimental alkali burned cornea in rabbit].

The model of experimental alkali burn of cornea in rabbit was obtained using 1 mol/L NaOH solution. After being burned for 1, 3, 7 and 14 days, the histochemical changes of these models were studied by using labelled concanavalin A (ConA-FITC) and wheat germ agglutinin (WGA-FITC). The results showed that after being burned, the amount of glycoconjugates interacted with these lectins decreased, and increased gradually after 7 days, then reached the level higher than that in the normal cornea. These changes were related to the recovery of alkali burned cornea.

Animals↗
PubMed1993

[Studies on diterpenoids from leaves of Tripterygium wilfordii].

Tripterygium wilfordii Hook f. has been used as a medicinal herb in traditional Chinese medicine and as an insecticide by the Chinese for hundreds of years. Recently, this plant has been used to treat cancer, rheumatic arthritis and various skin diseases in some Chinese clinics. It is of interest to note that Tripterygium also showed significant antifertility activities. The active principles of the anti-inflammatory, immunosuppressive and antifertile actions in Tripterygium are diterpenoid containing triepoxides, but information on its chemistry is limited to the woody part of the root and the root bark. Recently, we have studies the leaves of Tripterygium (collected at Zhejiang province, China), and isolated two novel diterpenoids by chromatography named tripdioltonide (8) and 13,14-epoxide 9,11,12-trihydroxytriptolide (9), besides triptonide (1), triptolide (2), tripdiolide (3), triptolidenol (4), 16-hydroxyl-triptolide (5), tripchlorolide (6) and triptriolide (7). Their structures were established by chemical reactions, TLC, UV, MS, IR, 1H-1H COSY, 1H-13C COSY, DEPT spectrometric investigation. The structure of tripdioltonide was further confirmed by X-ray analysis.

Diterpenes↗
PubMed1992

Effect of low glycogen on glycogen synthase in human muscle during and after exercise.

Subjects cycled at a work load calculated to elicit 75% of maximal oxygen uptake on two occasions: the first to fatigue (34.5 +/- 5.3 min; mean +/- SE), and the second at the same workload and for the same duration as the first. Biopsies were obtained from the quadriceps femoris muscle before and immediately after exercise, and 5 min post-exercise. Before the first experiment, muscle glycogen was lowered by a combination of exercise and diet, and before the second, experiment muscle glycogen was elevated. In the low glycogen condition (LG), muscle glycogen decreased from 169 +/- 15 mmol glucosyl units kg-1 dry wt at to rest to 13 +/- 6 after exercise. In the high glycogen condition (HG) glycogen decreased from 706 +/- 52 at rest to 405 +/- 68 after exercise. Glycogen synthase fractional activity (GSF) was always higher during the LG treatment. During exercise in the HG condition, those subjects who cycled for less than 35 min (n = 3) had GSF values in muscle which were lower than at rest, whereas those subjects who cycled for greater than 35 min (n = 4) had values which were similar to or higher than at rest. Thus the change in GSF in muscle during HG was positively related to the exercise duration (r = 0.94; y = 254-17x + 0.3x2; P less than 0.001) and negatively related to the glycogen content at the end of exercise (r = -0.82; y = 516-2x + 0.001x2; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effect of low glycogen on carbohydrate and energy metabolism in human muscle during exercise.

The effect of preexercise muscle glycogen content on the metabolic responses to exercise has been investigated. Seven men cycled at a work load calculated to elicit 75% of maximal oxygen uptake [211 +/- 17 (SE) W] on two occasions: 1) to fatigue (37.2 +/- 5.3 min) and 2) at the same work load and for the same duration as the first. Biopsies were obtained from the quadriceps femoris muscle before and after exercise. Before the first experiment, muscle glycogen was lowered by exercise and diet, and before the second experiment, muscle glycogen was elevated. In the low-glycogen condition (LG), muscle glycogen decreased from 182 +/- 15 at rest to 7 +/- 4 mmol glucosyl units/kg dry wt at fatigue, while in the high-glycogen condition (HG), glycogen decreased from 725 +/- 31 at rest to 353 +/- 53 mmol glucosyl units/kg dry wt at the end of exercise. Hexose monophosphates were not increased after LG exercise but increased approximately fivefold after HG exercise. Lactate increased more during HG exercise (LG = 16 +/- 5, HG = 61 +/- 7 mmol/kg dry wt; P less than or equal to 0.001), whereas IMP increased more during LG (LG = 2.8 +/- 0.6, HG = 0.9 +/- 0.2 mmol/kg dry wt; P less than or equal to 0.05). The increases in the sum of tricarboxylic acid cycle intermediates (TCAI; citrate+malate+fumarate) and acetylcarnitine (which is in equilibrium with acetyl CoA) were significantly greater during HG exercise (P less than or equal to 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood↗
PubMed1992

Platelet factor 4 efficiently reverses heparin anticoagulation in the rat without adverse effects of heparin-protamine complexes.

BACKGROUND: It has been observed that the reversal of heparin anticoagulation in humans by protamine sulfate (PS) results in various adverse reactions including leukopenia, thrombocytopenia, activation of complement, increased vascular permeability, systemic hypotension, pulmonary vasoconstriction, and pulmonary edema. The purpose of this study was to compare the efficacy and effects of native platelet factor 4 (PF4) and recombinant platelet factor 4 (rPF4) with those of PS in heparin neutralization in vivo, using a rat model. METHODS AND RESULTS: Sprague-Dawley rats were anesthetized with sodium pentobarbital, and the right femoral vein and carotid artery were cannulated. For determination of activated partial thromboplastin time, platelet count, white blood cell count, and complement titer, arterial blood samples were taken before and immediately after heparin (10 units/100 g) infusion and at several time points after the infusion of the neutralizing agent (PS, 0.1 mg/100 g; PF4, 0.5 mg/100 g). In separate groups of animals, mean arterial blood pressure was monitored throughout identical protocols and the lungs were prepared for histological examination. The anticoagulant activity of heparin was effectively reversed by all of the neutralizing agents (PS, PF4, and rPF4). Platelet count (48% of initial), white blood cell count (52% of initial), complement titer (60% of initial), and mean arterial pressure (20% decrease) decreased significantly in heparinized animals receiving PS but not in those receiving PF4 or rPF4. Lung interstitium appeared normal when heparin was followed by PF4; however, interstitial edema and hemorrhage were observed with heparin-PS. CONCLUSIONS: These results suggest that PF4 efficiently reverses heparin anticoagulation in the rat without the adverse effects of heparin-protamine complexes. Therefore, rPF4 may be an appropriate substitute for PS in patients undergoing cardiovascular surgery and other procedures that require heparin anticoagulation.

Animals↗
PubMed1992

Studies on the luminescence of channels in rats and its law of changes with "syndromes" and treatment of acupuncture and moxibustion.

We previously reported the discovery of 14 channels in the human body, which possessed the biophysical property of high emission of light. In this study we found the same property on the Ren and Du channels in healthy rats. Additionally, we discovered that the luminance of the related channels in rat models with different "syndromes" varied greatly. For instance, a markedly low luminance appeared on the Du channel in animals with experimental syndrome of Yang deficiency induced by hydrocortisone; while in animals with experimental syndrome of blood deficiency caused by bleeding, an apparently low luminance occurred on the Ren channel. The intensity of the emitted light on Du and Ren channels increased after acupuncture treatment, but not significantly. This phenomenon conforms to the theory in traditional Chinese medicine that the Du channel is the "sea of Yang channels", while the Ren channel is the "sea of Yin channels".

Acupuncture Therapy↗
PubMed1992

Screening of bacterial strains producing maltotetraose-forming amylase and the conditions for enzyme production.

The authors isolated 1380 bacterial strains from 290 soil samples collected in China and 490 strains were received from other research teams in this institute. By screening 707 strains showed starch-hydrolyzing activity. By further screening and paper chromatographic test, three strains with maltotetraose as the major product were obtained. The maltotetraose was further confirmed by treatment with beta-amylase splitting to maltose and with glucoamylase to glucose. The most promising strain was 537.1, which produced maltotetraose about 90% (w/w) in the starch hydrolysate. While the other two strains produced maltose and maltotriose besides maltotetraose. Strain 537.1 was tentatively identified as Alcaligenes sp. The optimum conditions for enzyme production were as follows: medium composition: 1.5% maltose; 0.5% peptone with initial pH of 7.0-7.5; cultured at 27-28 degrees C for 48 hours on rotary shaker. The culture supernatant of the strain 537.1 can hydrolyze starch and different kinds of cereal flour with a high yield of maltotetraose in the hydrolysate.

Bacteria↗
PubMed1992

Two roles for transforming growth factor beta 1 in colon enterocytic cell differentiation.

The role of transforming growth factor beta 1 (TGF-beta 1) in enterocytic differentiation was examined by treating two undifferentiated HT29 colon carcinoma sublines, U4 and U9, with hexamethylene bisacetamide to up-regulate their level of TGF-beta 1 mRNA expression. Although both lines after treatment secreted approximately equal levels of biologically active TGF-beta 1, only U4H cells were found to undergo enterocytic differentiation when cultured postconfluence on collagen I-coated transwells, forming polarized monolayer cells with an apical brush border, whereas U9H cells remained multilayered and undifferentiated. Enterocytic U4H cells exhibited four times as much cell surface expression of the collagen I-binding protein alpha 2-integrin, twice as much of the accessory collagen-binding protein carcinoembryonic antigen, and almost twice as much binding to collagen I films as undifferentiated U9H cells. TGF-beta 1 treatment doubled U4 cell collagen I binding, increased expression of alpha 2-integrin 4-fold, but increased carcinoembryonic antigen expression only marginally. U4H cells displayed cell cycle regulation by arresting reversibly at a restriction point in G1 when placed in the postconfluent culture conditions which initiated enterocytic differentiation. In contrast, undifferentiated U9H cells exhibited no restriction point but arrested throughout G1. TGF-beta 1 blocked synchronized U4H cells in G1, whereas it stimulated the growth of U9H cells. Thus, TGF-beta 1 has two roles in enterocytic differentiation: to increase levels of collagen I adhesion proteins and to block enterocytic cells in G1 so that they can differentiate.

Acetamides↗
PubMed1992

Transforming growth factor beta 1 (TGF-beta 1) inhibits retinoblastoma gene expression but not pRB phosphorylation in TGF-beta 1-growth stimulated colon carcinoma cells.

The response of the retinoblastoma (RB) gene and its product (pRB) to transforming growth factor beta 1 (TGF-beta 1) was studied in three types of colon carcinoma cells derived from the same parental line. TGF-beta 1 was a growth inhibitor for two enterocytic-differentiated lines, a growth stimulator for two undifferentiated lines, and had no effect on two goblet cell-differentiated lines. TGF-beta 1 treatment for 3 days decreased RB gene expression and pRB level two- to threefold in each responsive line. When treated with TGF-beta 1 beginning in early G1, enterocytic cells were arrested in G1 and pRB remained under-phosphorylated and in low abundance. Neither goblet cell line exhibited these responses to TGF-beta 1 because they were shown to lack TGF-beta 1 type I and II receptors. Thus during colonocyte differentiation goblet cells lose responsiveness to TGF-beta 1 by down-regulating TGF-beta 1 receptors, while enterocytic cells retain and exhibit responsiveness to TGF-beta 1 through modulations of pRB. Both of the undifferentiated lines exhibited mixed responses to TGF-beta 1: a decrease in total amount of RB mRNA and pRB protein yet an increase in pRB phosphorylation consistent with increased cell cycling. Therefore, TGF-beta 1 controls RB function by two separable mechanisms, the regulation of pRB phosphorylation and the control of RB mRNA and protein level.

Carcinoma↗
PubMed1991

Carbohydrate supplementation attenuates IMP accumulation in human muscle during prolonged exercise.

The effect of carbohydrate (CHO) ingestion on metabolic responses to exercise has been investigated. Subjects cycled at approximately 70% of maximal oxygen uptake to fatigue [135 +/- 17 (+/- SE) min] on the first occasion (control, CON) and at the same work load and duration on the second occasion but with addition of ingestion of CHO during the exercise. Biopsies were taken from the quadriceps femoris muscle before and after exercise. The sum of the hexose monophosphates (HMP), as well as lactate and alanine, in muscle was higher after CHO exercise (P less than or equal to 0.05, P less than or equal to 0.05, and P less than or equal to 0.01, respectively). Acetylcarnitine increased during exercise but was not significantly different between treatments after exercise (CON, 6.6 +/- 1.7; CHO, 10.0 +/- 1.2 mmol/kg dry wt; P = NS). The sum of the tricarboxylic acid cycle intermediates (TCAI; citrate + malate + fumarate) was increased during exercise and was higher after CHO exercise (2.34 +/- 0.32 vs. 1.68 +/- 0.17 mmol/kg dry wt; P less than or equal to 0.05). IMP was less than 0.1 mmol/kg dry wt at rest and increased to 0.77 +/- 0.26 (CON) and 0.29 +/- 0.11 mmol/kg dry wt (CHO) (P less than or equal to 0.05) during exercise. It was recently found that during prolonged exercise there is initially a rapid and large expansion of TCAI and glycogenolytic intermediates in human muscle followed by a continuous decline in TCAI and glycogenolytic intermediates [K. Sahlin, A. Katz, and S. Broberg. Am. J. Physiol. 259 (Cell Physiol. 28): C834-C841, 1990].(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Basal and insulin-mediated carbohydrate metabolism in human muscle deficient in phosphofructokinase 1.

Biopsies were obtained from the quadriceps femoris muscle of two male patients deficient in phosphofructokinase (PFK) 1. In the basal state the patients had markedly higher contents of UDP-glucose (approximately 5-fold), hexose monophosphates (approximately 7- to 13-fold), inosine monophosphate (IMP) (approximately 15-fold), and fructose 2,6-bisphosphate (F-2,6-P2; approximately 6-fold) than controls. Fructose 1,6-bisphosphate was not detectable, and phosphocreatine was lower (33 and 54 mmol/kg dry wt) than in controls [72 +/- 4 (SD)]. Patients had normal fasting plasma glucose and insulin levels and basal glucose turnover rates and responded normally to a 75-g oral glucose challenge. Patients were also studied during euglycemic hyperinsulinemia (approximately 95 mg/dl; 40 and 400 mU.m-2.min-1). Whole body glucose disposal rates were normal during both insulin infusion rates. Biopsies taken after the 400 mU insulin infusion showed decreases in acetylcarnitine and citrate and increases in the fractional activity of glycogen synthase. It is suggested that the high basal levels of F-2,6-P2 are, at least partly, a consequence of the high levels of fructose 6-phosphate, which will stimulate flux through PFK-2 and inhibit fructose-2,6-bisphosphatase. The low phosphocreatine and high IMP contents indicate that carbohydrate availability is important for control of high-energy phosphate metabolism, even in the basal state. The insulin-mediated decreases in acetylcarnitine and citrate suggest an activation of the tricarboxylic acid cycle in skeletal muscle but an absence of the normal response to replenish these intermediates.

Carbohydrate Metabolism↗
PubMed1991

Fasting inhibits insulin-mediated glycolysis and anaplerosis in human skeletal muscle.

Euglycemic (approximately 5.5 mM) hyperinsulinemic (60 mU.m-2.min-1) clamps were performed for 2 h after a 10-h fast and after a prolonged (72-h) fast. Biopsies were obtained from the quadriceps femoris muscle before and after each clamp. The rate of whole body glucose disposal was approximately 50% lower during the clamp after the 72-h fast (P less than or equal to 0.001). The increase in carbohydrate (CHO) oxidation (which is proportional to glycolysis) during the clamp after the 10-h fast (to 13.8 +/- 1.5 mumol.kg fat free mass-1.min-1) was completely abolished during the clamp after the 72-h fast (1.7 +/- 0.6; P less than or equal to 0.001). During the clamp after the 10-h fast, postphosphofructokinase (PFK) intermediates and malate in muscle increased, whereas glutamate decreased (P less than or equal to 0.05-0.001 vs. basal) and citrate did not change. During the clamp after the 72-h fast, there were no significant changes in post-PFK intermediates or glutamate (P greater than 0.05 vs. basal), but there was a decrease in citrate (P less than or equal to 0.01 vs. basal). Euglycemic hyperinsulinemia increased glycogen synthase fractional activity in muscle under both conditions but to a greater extent after the 72-h fast (P less than or equal to 0.01). It is concluded that insulin (after 10-h fast) increases glycolytic flux and the content of malate in muscle, which is probably due to increased anaplerosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Identification of Chinese drugs by fluorescence spectrum].

Cortex Fraxini, Radix et Rhizoma Rhei, Semen Astragali Complanati, Semen Lini, Bulbus Fritillariae Cirrhosae, Bulbus Fritillariae Thunbergii and their confused medicinal materials have been identified by the fluorescence spectrum. This is a referential method for the identification of Chinese drugs.

Drug Contamination↗
PubMed1991

[Anti-tumor effect of Cetraria laevigata Rassad. polysaccharides].

The anti-tumor effect of Cetraria laevigata polysaccharides has been investigated in mice using sarcoma 180; Ehrlich ascitic tumor, cervical carcinoma u-14 and leukemia L7217. The results show that Cetraria laevigata polysaccharides may inhibit the growth of sarcoma 180, Ehrlich ascitic tumor and cervical carcinoma u-14 in mice at a dose of 200mg/kg ip (1/5 LD50). However, the survival time of leukemia L7217 wasn't prolonged. The reticuloendothelial system phagocytic function in mice was increased at ip doses of 50 mg/kg and 100 mg/kg (1/10 and 1/20 LD50).

Animals↗
PubMed1990

[Purification and characterization of beta-N-acetyl hexosaminidase from Aspergillus tamarii].

A beta-N-acetylhexosaminidase from mycelium-free culture filtrate of Asp tamarii S215 was purified to PAGE homogenous by ammonium sulfate and polyethylene glycol fractionation precipitation followed by Sephadex G-50 desalt, DEAE-Sephadex A-25 chromatography, hydroxyapatite chromatography and DEAE-Sephadex A-25 rechromatography with 170-fold purification and 24.7% recovery. The ratio of the beta-GlcNAcase and beta-GalNAcase was 2.5 and remained constant throughout the purification. The Mr estimated with concentration gradient PAGE was 140,000 and subunit Mr determined with SDS-PAGE was 72,000, the number of subunit were 2. The pI was 4.2 determined by PAGIEF. The optimum pH was 5.5-6.5 and 5.0-6.0 for beta-GlcNAcase and beta-GalNAcase respectively with stable pH range 5.5-8.3 for both. The optimum temperature was 60 degrees C for beta-GlcNAcase and beta-GalNAcase. The residual activity of beta-GlcNAcase was 52.7% after treated at 50 degrees C for 8 h and it was 44.9% for beta-GalNAcase. The residual activities of both were down to 1% after treated at 62 degrees C for 10 min. The activity was slightly activated by Mn2+ or Fe2+, while strongly inhibited by Hg2+ and slightly by Ag+, Cu2+, Pb2+, Cd2+ or Zn2+. Analyses of amino acids composition showed that the beta-HexNAcase contained about 24.2% acidic amino acids and 14.9% basic amino acids and only 0.6% methionine.

Acetylglucosaminidase↗
PubMed1990

[Analysis of essential oils in roots and fruits of Angelica in Northeast China].

The essential oils of roots and fruits of five species of Angelica have been examined and analysed by GC-MS-DS; 59 chemical compounds are reported, of which alpha-pinene, myrcene and p-cymene are common to all five species. This paper provides a scientific basis for developing the resources of this genus in the Northeast.

Acyclic Monoterpenes↗
PubMed1990

[Construction and application of atropine flow-through sensor in flow injection analysis].

A new kind of flow-through sensor for atropine has been studied. It exhibits Nernstian response for atropine with a slope of 54 +/- 1 mV/decade over the concentration range of 0.02-200 mmol/L at pH 5-8. The sensitivity coefficients of common compounds were determined. Only bromo-geramine, clonidine, strychnine and amantadine showed remarkable interference. Direct potentiometry for determination of atropine showed an average recovery of 99.2% and a relative standard deviation of 1.3%. It has been used in flow injection analysis (FIA) of atropine, anisodamine and scopolamine and belladonna preparations. Rate of analysis of as high as 60-100 samples/h was achieved.

Atropa belladonna↗