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Biomedical subjects

G Zhu

Publications and source records attributed to G Zhu.

At least 271 records · Page 15Linked to original sources
PubMed1991

Collagen metabolism during healing of lacerated rabbit corneas.

We previously demonstrated that there are two waves of increased collagen synthesis following corneal laceration in rabbits. In the present study, we have examined whether increases in collagen synthesis and degradation result from increased amounts of mRNAs for collagen and collagenase, respectively. Rabbits were anesthetized by combined administration of ketamine (intramuscular) and pentobarbital (intravenous). A penetrating 8-mm incision was made at the center of each cornea. The lacerated corneas were allowed to heal for 0-49 days. The rabbits were then killed and the corneas excised. The total RNA was extracted from the tissue and subjected to slot-blot hybridization using 32P-labeled alpha 1(I) cDNA. The results indicate that there is a two-phase increase in the amount of alpha 1(I) mRNA in injured corneas and that the collagenase mRNA is elevated at most times throughout the healing period. However, the increase is collagenase mRNA may not fully account for the accelerated collagen degradation during corneal wound-healing. Thus, we propose that cells in the wound area may be directly involved in collagen degradation by phagocytosis. To examine our hypothesis, we cultured injured rabbit corneas in the presence or absence of leupeptin, a proteinase inhibitor. The tissues were then examined by electron microscopy. In the presence of leupeptin, lysosomes within fibroblasts or fibroblast-like cells in the wound area of the lacerated corneas healed for 2 and 3 weeks, contain collagen fibrils. In the absence of leupeptin no identifiable collagen was seen in the lysosomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Xylulose 1,5-Bisphosphate Synthesized by Ribulose 1,5-Bisphosphate Carboxylase/Oxygenase during Catalysis Binds to Decarbamylated Enzyme.

Xylulose 1,5-bisphosphate (XuBP) is synthesized from ribulose 1,5-bisphosphate (RuBP) at carbamylated catalytic sites on ribulose 1,5-bisphosphate carboxylase (Rubisco) with significant amounts of XuBP being formed at pH less than 8.0. XuBP has been separated by high performance liquid chromatography and identified by pulsed amperometry from compounds bound to Rubisco during catalysis with the purified enzyme and from celery (Apium graveolens var Utah) leaf extracts. XuBP does not bind tightly to carbamylated sites, but does bind tightly to decarbamylated sites. Upon incubation of fully activated Rubisco with 5 micromolar XuBP, loss of activator CO(2) occurred before XuBP bound to the enzyme catalytic sites, even in the presence of excess CO(2) and Mg(2+). Binding of XuBP to decarbamylated Rubisco sites was highly pH dependent. At pH 7.0 and 7.5 with 10 millimolar MgCl(2) and 10 millimolar KHCO(3), the apparent dissociation constant for XuBP, K(d), was 0.03 micromolar, whereas at pH 8.0 and 8.5, the apparent K(d) was 0.35 and 2.0 micromolar, respectively. This increase in K(d) with pH was a result of a decrease in the association rate constant and an increase in the dissociation rate constant of XuBP bound to decarbamylated sites on Rubisco. The K(d) of 2-carboxyarabinitol 1-phosphate binding to carbamylated sites was only slightly pH dependent.

Journal Article↗
PubMed1991

Fallover of Ribulose 1,5-Bisphosphate Carboxylase/Oxygenase Activity : Decarbamylation of Catalytic Sites Depends on pH.

Loss of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity during CO(2) fixation, called fallover, occurred with or without loss of activator CO(2) from catalytic sites depending on pH. At pH 7.5, but not at pH 8.5, the fraction of Rubisco sites that were carbamylated decreased during fallover. Inhibitors which formed during fallover were identified following NaBH(4) reduction and separation of the products by high performance anion-exchange chromatography and pulsed amperometric detection. They were xylulose 1,5-bisphosphate (XuBP) and 3-ketoarabinitol 1,5-bisphosphate. During fallover at pH 8.5, 3-ketoarabinitol-P(2) was the only inhibitor binding to Rubisco and this binding was at carbamylated sites, although both inhibitors were made. At pH 7.5, both inhibitors were bound to catalytic sites of Rubisco with XuBP bound tightly to decarbamylated sites, whereas 3-ketoarabinitol-P(2) bound to carbamylated sites. The pH during fallover also influenced the ratio of 3-ketoarabinitol-P(2) to XuBP formed. When fallover occurred at pH 7.5, both the formation of XuBP and its binding affinity to decarbamylated Rubisco sites were increased compared with those at pH 8.5. 3-Ketoribitol-P(2) was not found at either pH.

Journal Article↗
PubMed1991

A historical demography of Chinese migration.

Trends in international migration from China are analyzed from historical times to the present. "The study will involve discussions about the nature of migration and the different forms it took in five different stages, in the light of 1) changes in motivation, 2) type of migration, and 3) the distribution of the out-going population."

Asia↗
PubMed1991

[Percutaneous transluminal coronary angioplasty. A report of 100 cases].

Percutaneous transluminal coronary angioplasty (PTCA) was performed in 100 coronary heart patients with 122 vessels and 138 lesions dilated. Among these 100 cases, there were 39 complex PTCA performed. The primary success rate was 93% (93/100), was 94.3% (115/122) according to vessel dilated and was 92.1% (127/138) according to lesion dilated. In 4 cases whose lesions were located at the bifurcation of the vessel, kissing balloon technique via a single guiding catheter was applied with success. In 5 cases of total occlusion PTCA was performed with success in 4. PTCA with stent in 1. PTCA was performed in 1 cases of high risk whose LVEF was only 30% and coronary hemoperfusion pump was used during the procedure. Emergency PTCA was performed in 3 AMI patients during the acute phase and elective PTCA in 8 AMI cases after successful thrombolytic therapy. There were complications in 9 cases (9%). Among these 9 cases, 2 developed O-wave MI which recovered after medicinal therapy. One AMI complicated with heart failure was treated by emergency PTCA with success, but the patient died 10 days after PTCA due to pump failure and pulmonary infection. There were no deaths due to PTCA, nor was emergency coronary artery bypass graft (CABG) performed. These cases were followed for 1-30 months on an average of 13 months. Clinical success rate was 91.3%. The clinical success rate was 93.1% by 201Tl perfusion study. Restenosis in 7 cases was confirmed by coronary angiography. For these restenotic cases, PTCA was repeated with success in 4, CABG performed in 1, coronary atherectomy in 1, and medicinal therapy employed in 1 patient.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Anti-inflammatory, analgesic and sedative effects of Leontice kiangnanensis P.L. Chiu].

The ethanolic extract of Leontice kiangnanensis (EELK) can inhibit obviously the increased permeability of abdominal blood capillaries and the ear inflammation in mice as well as the swelling of hind paw and the proliferation of granuloma induced by cotton-pellets in rats, EELK can also raise the pain thresholds during hot-plate, formaldehyde and writhing tests in mice. Use of EELK together with pentobarbital may enhance sedative effect on mice.

Animals↗
PubMed1990

Status of the substrate binding sites of ribulose bisphosphate carboxylase as determined with 2-C-carboxyarabinitol 1,5-bisphosphate.

The properties of the tight and specific binding of 2-C-carboxy-d-arabinitol 1,5-bisphosphate (CABP), which occurs only to reaction sites of ribulose 1,5-bisphosphate carboxylase (Rubisco) that are activated by CO(2) and Mg(2+), were studied. With fully active purified spinach (Spinacia oleracea) Rubisco the rate of tight binding of [(14)C]CABP fit a multiple exponential rate equation with half of the sites binding with a rate constant of 40 per minute and the second half of the sites binding at 3.2 per minute. This suggests that after CABP binds to one site of a dimer of Rubisco large subunits, binding to the second site is considerably slower, indicating negative cooperativity as previously reported (S Johal, BE Partridge, R Chollet [1985] J Biol Chem 260: 9894-9904). The rate of CABP binding to partially activated Rubisco was complete within 2 to 5 minutes, with slower binding to inactive sites as they formed the carbamate and bound Mg(2+). Addition of [(14)C]CABP and EDTA stopped binding of Mg(2+) and allowed tight binding of the radiolabel only to sites which were CO(2)/Mg(2+)-activated at that moment. This approach estimated the amount of CO(2)/Mg(2+)-activated sites in the presence of inactive sites and carbamylated sites lacking Mg(2+). The rate of CO(2) fixation was proportional to the CO(2)/Mg(2+)-activated sites. During light-dependent CO(2) fixation with isolated spinach chloroplasts, the amount of carbamylation was proportional to Rubisco activity either initially upon lysis of the plastids or following total activation with Mg(2+) and CO(2). Lysis of chloroplasts in media with [(14)C]CABP plus EDTA estimated those carbamylated sites having Mg(2+). The loss of Rubisco activation during illumination was partially due to the lack of Mg(2+) to stabilize the carbamylated sites.

Journal Article↗
PubMed1990

[Changes in bile composition in rabbits infected with Clonorchis sinensis].

This article presents the changes in the concentration of bilirubin, cholesterol, phospholipid, bile acid and the activity of bacterial beta-glucuronidase in hepatic bile of rabbits infected with metacercariae of Clonorchis sinensis. We found that the activity of bacterial beta-glucuronidase was significantly higher in the infected group (52.6 +/- 31.6 u/dl) than that in control rabbits (12.5 +/- 20.5 u/dl) (P less than 0.001), and no marked changes in the concentration of bilirubin, cholesterol, phospholipid and bile acid were found. concentration of bilirubin, cholesterol, phospholipid and bile acid were found. By using alcian blue-PAS combined stain method the authors also noticed that the amount of glycoprotein in goblet cells has considerably increased and secreted increasingly to the biliary duct after infection with Clonorchis sinensis. As the increase in bacterial beta-glucuronidase activity and glycoprotein in bile is in favour of the formation of pigment stone, this may explain why clonorchiasis is often complicated with cholelithiasis.

Animals↗
PubMed1990

[Effects of Codonopsis pilosulae on the synthesis of thromboxane A2 and prostacyclin].

24 angina pectoris patients were treated with Codonopsis pilosulae (CP) oral solution 20 ml (containing crude CP 20 g) thrice daily for 7 days, other 10 cases were treated by aspirin 0.5 g per day for a week as the control group. After treatment, in the CP group, the plasma level of TXB2 was obviously reduced from 156.76 +/- 11.87 pg/ml to 125.01 +/- 8.85 pg/ml (means +/- S means), the inhibitory rates was 15. 67% (P less than 0.05), and of 6-keto-PGF1 alpha (6-K) was not markedly changed (P greater than 0.05). In the aspirin group, TXB2 was also reduced significantly (P less than 0.05); 6-K was reduced more than that of CP group, the inhibitory rate was 24.33 +/- 9.40% (P less than 0.05). To reveal the mechanism of CP action on the synthesis of TXA2 and PGI2, the porcine lung microsome was used as the donor of cyclooxygenase, thromboxane synthase and prostacyclin synthase, the effects of CP on the formation of TXB2 and 6-K from arachidonic acid (AA) or endoperoxides were measured by RIA respectively. The results showed that both the levels of the formation of TXB2 from AA or endoperoxides were markedly reduced by CP in a dose-dependent (at doses of 3-300 mg/ml). The synthesis of TXB2 was distinctly inhibited alone with a dose of 100 mg/ml CP, which suggested that CP might be an inhibitor of TXB2 synthase at that dose; while at a dose of 300 mg/ml CP, the synthesis of TXB2 and 6-K were inhibited simultaneously (P less than 0.001). It showed that a larger dosage of CP, which could inhibited the synthesis of both TXA2 and PGI2, its mechanism of action needs further study.

6-Ketoprostaglandin F1 alpha↗
PubMed1990

Metabolism of normal skeletal muscle during dynamic exercise to clinical fatigue: in vivo assessment by nuclear magnetic resonance spectroscopy.

In vivo nuclear magnetic resonance (NMR) spectroscopy was used to define several intracellular high energy phosphate variables of the gastrocnemius muscle of normal subjects during rest, graded plantar flexion exercise to exhaustion, and recovery. There were nine males and eight females with an average age of 34 +/- 8 years. At rest, pH averaged 7.09 +/- 0.03 and the energy cost index (ECI)--the ratio of inorganic phosphate to phosphocreatine--averaged 0.13 +/- 0.03. At peak exercise, the ECI increased markedly to 2.71 +/- 2.0 (P less than 0.001) and pH fell precipitately to 6.76 +/- 0.17 (P less than 0.001), indicating the high intensity of the exercise. Exercise endurance averaged 12 +/- 5 mins; it was not highly correlated with sex, age (r = 0.35), rest pH (r = 0.26), rest ECI (r = 0.38), peak exercise pH (r = 0.23) or peak exercise ECI (r = 0.38), nor exercise changes in pH (r = 0.17) and ECI (r = 0.28). At 23 mins post exercise all variables were similar to rest. Rest pH was the only variable different between males (7.10 +/- 0.03) and females (7.07 +/- 0.03) (P less than 0.05). Thus, dynamic exercise of large skeletal muscles in normal subjects was characterized by marked temporal changes in high energy phosphate profiles and very low pH at exhaustion. No single metabolic variable correlated highly with exercise endurance, suggesting that the intracellular pathophysiology of exhaustive muscle exercise and clinical fatigue may be multifactorial.

Adult↗
PubMed1990

Effects of purified compound (8501) on hyperlipidemia and the balance between thromboxane A2 and prostacyclin in rabbits.

New Zealand strain white male rabbits were divided into four groups to study the effects of 8501, extracted from a Chinese herb, on hyperlipidemia and the TXA2/PGI2 ratio in atherosclerotic rabbits. The results indicate that serum cholesterol and the levels of cholesterol and cholesteryl ester in aortic tissue were significantly increased in cholesterol-fed rabbits. The percentage of alpha-lipoprotein was significantly decreased and the aortic atherosclerotic plaque area was significantly increased. The data also demonstrate that the level of plasma TXB2 was markedly increased, while that of 6-keto-PGF1 alpha was significantly decreased. The TXB2/6-keto-PGF1 alpha ratio (T/6) was significantly increased. The decrease of 6-keto-PGF1 alpha occurred prior to the increase of TXB2. Compound 8501 not only lowered serum total cholesterol and aortic total cholesterol and cholesteryl ester but also antagonized the decrease of alpha-lipoprotein and atherosclerotic plaque formation. In addition, 8501 prevented the decrease of plasma 6-keto-PGF1 alpha and the increase of TXB2, and so the T/6 ratio was significantly decreased.

6-Ketoprostaglandin F1 alpha↗