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Biomedical subjects

B Zhou

Publications and source records attributed to B Zhou.

At least 145 records · Page 8Linked to original sources
PubMed1997

In-vitro apatite formation on phosphorylated bamboo.

Natural self-reinforced composite, bamboo, was surface modified by phosphorylation with urea-H3PO4 and NaOH-H3PO4 methods; then precalcification was performed by immersing samples in saturated Ca(OH)2 solution. After that, calcium phosphate can be formed on the surface of bamboo samples in calcification media: simulated body fluid (1.5 SBF) and accelerated calcification solution (ACS). Experimental results reveal that pre-calcification is an inevitable step for the formation of calcium phosphate. The calcium phosphate formed in 1.5 SBF was identified by thin-film X-ray diffraction as apatite which was not well crystallized. Compared with the urea-H3PO4 method, the NaOH-H3PO4 method has the advantages of quicker and continuous apatite formation and stronger adhesive between apatite and bamboo.

Journal Article↗
PubMed1997

Identification of a 175 kDa protein as the ligand-binding subunit of the rat liver sinusoidal endothelial cell hyaluronan receptor.

The rat liver sinusoidal endothelial cell (LEC) hyaluronan (HA) receptor was previously identified using a photoaffinity HA derivative (J. Biol. Chem., 267, 20451-20456, 1992). Two polypeptides with M(r) = 175,000 and 166,000, were consistently crosslinked, suggesting that the LEC HA receptor is an oligomer. Whether one or both subunits participate in HA binding, was not determined. Here we investigate the HA-subunit interactions and the potential oligomeric nature of the LEC HA receptor. When Sephacryl-400 gel filtration chromatography was used to enrich the HA receptor, the 175 kDa polypeptide was the major band seen by SDS-PAGE analysis. Little staining was seen at 166 kDa, suggesting that the 175 kDa protein could be separated from the 166 kDa protein and still retain HA-binding activity. A ligand blot assay was used to determine if each individual subunit could bind HA. LEC proteins were separated by nonreducing SDS-PAGE, and then immobilized onto nitrocellulose. 125I-HA bound to a 175 kDa polypeptide but not to the 166 kDa protein. A high molecular weight band of approximately 300,000 also bound 125I-HA. 125I-HA binding to the 175 and 300 kDa proteins showed the same specificity of competition with a panel of carbohydrates as the bona fide LEC HA receptor. The 175 kDa HA-binding subunit may be nonglobular (asymmetric), since its apparent size by SDS-PAGE is dependent on the polyacrylamide gel pore size; M(r) increases as porosity decreases. LECs were crosslinked to an 125I-labeled photoaffinity HA derivative and the HA saccharides were then released with hyaluronidase. After SDS-PAGE without reduction, radiolabeled bands were seen at 175 and 166 kDa (3:1 ratio), and a high MW (approximately 300,000) species was also detected. These data support an oligomeric model of the LEC HA receptor, and show that the 175 kDa protein possesses HA-binding activity independent from the 166 kDa polypeptide.

Animals↗
PubMed1997

Basic fibroblast growth factor reduces the gut and liver morphologic and functional injuries after ischemia and reperfusion.

OBJECTIVE: To explore the possible effects of basic fibroblast growth factor (bFGF) on ischemic gut and liver injuries after trauma. METHODS: Animal models of superior mesenteric artery occlusion (45 minutes) and reperfusion (3 days) were used in this study. Seventy-two Wistar rats were divided into three groups of 24 rats each. The animals in bFGF-treated group were injected with 4 microg bFGF/rat in 0.15 mL normal saline solution containing heparin 0.1% (w/v) through the jugular vein at the onset of reperfusion. In the normal saline control group, all rats received the same vehicle, but without bFGF. Group 3 (sham-operated) underwent the same laparotomy procedure, but without superior mesenteric artery occlusion. Liver function parameters, the levels of serum tumor necrosis factor alpha, nitric oxide, superoxide dismutase, malondialdehyde (MDA), tissue bacterial examination, and pathologic study were used to evaluate the results. RESULTS: In bFGF-treated rats, the amounts of serum alanine transaminase and aspartate aminotransferase and serum tumor necrosis factor-alpha were reduced significantly at 6, 24, and 48 hours when compared with normal saline-treated rats. However, the changes in nitric oxide, superoxide dismutase, and MDA varied from each other as a function of time after injury. The amounts of nitric oxide were increased significantly at 6 hours in intestine in normal saline-treated rats and in liver in bFGF-treated rats (p < 0.05). At 6 hours after reperfusion, the activity of superoxide dismutase in normal saline-treated rats were much lower in liver than those in bFGF-treated and sham-operated rats (p < 0.05), but the levels of MDA were increased in intestine in bFGF-treated rats and in liver in normal saline-treated rats when compared with sham-operated rats (p < 0.05). At 24 hours, the levels of MDA in normal saline-treated rats were much higher than those in both bFGF and sham-operated rats (p < 0.05). Bacterial examination revealed that the ratio and the amounts of bacterial translocation from gut to liver, spleen, and mesenteric lymph nodes in bFGF-treated rats were much lower than those in normal saline-treated rats. The results of pathologic study support the assumption that bFGF provided protective effects against reperfusion injury. CONCLUSIONS: Intravenous administration of bFGF may benefit in reducing gut and liver injuries after ischemia and reperfusion. The mechanisms of those effects may involve mitogenic and nonmitogenic effects of bFGF.

Animals↗
PubMed1997

Phosphorylation of rat muscle acetyl-CoA carboxylase by AMP-activated protein kinase and protein kinase A.

This study was designed to compare functional effects of phosphorylation of muscle acetyl-CoA carboxylase (ACC) by adenosine 3',5'-cyclic monophosphate-dependent protein kinase (PKA) and by AMP-activated protein kinase (AMPK). Muscle ACC (272 kDa) was phosphorylated and then subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by autoradiography. Functional effects of phosphorylation were determined by measuring ACC activity at different concentrations of each of the substrates and of citrate, an activator of the enzyme. The maximal velocity (Vmax) and the Michaelis constants (Km) for ATP, acetyl-CoA, and bicarbonate were unaffected by phosphorylation by PKA. Phosphorylation by AMPK increased the Km for ATP and acetyl-CoA. Sequential phosphorylation by PKA and AMPK, first without label and second with label, appeared to reduce the extent of label incorporation, regardless of the order. The activation constant (Ka) for citrate activation was increased to the same extent by AMPK phosphorylation, regardless of previous or subsequent phosphorylation by PKA. Thus muscle ACC can be phosphorylated by PKA but with no apparent functional effects on the enzyme. AMPK appears to be the more important regulator of muscle ACC.

Acetyl-CoA Carboxylase↗
PubMed1997

Protection of ebselen against anoxic damage of cultured neurons of cerebral cortex.

AIM: To study the protective effect of ebselen on anoxic damage of brain cells. METHODS: On d 10 after plating of the cortical neurons from 1-d-old rat, cultures were placed under 95% N2 + 5% CO2 for 2-6 h. Lactate dehydrogenase (LDH) in supernatant, thiobarbituric acid reactive substance (TBARS) and glutathione peroxidase (GSH-Px) activity of neurons were determined. RESULTS: Under anoxia, efflux of LDH and TBARS from cultured neurons increased while GSH-Px activity decreased. Ebselen reduced the efflux of LDH and TBARS in a dose-related manner and increased the total GSH-Px activity. CONCLUSION: Ebselen can protect neurons from anoxic damage.

Animals↗
PubMed1997

Effects of Ro 31-8220 on smooth muscle cell proliferation induced by fibrinogen degradation products.

AIM: To study the mitogenic activity of fibrin fibrinogen degradation products (FFDP) and the effect of a new selectively potent protein kinase C (PKC) inhibitor Ro 31-8220 (Ro). METHODS: Rat aortic smooth muscle cells (SMC) proliferation in culture was measured by crystal violet staining assay. RESULTS: FFDP stimulated the proliferation of SMC during the experimental period of 72 h, Ro 0.01-1 mumol.L-1 inhibited FFDP-induced cell proliferation in a concentration-dependent manner. CONCLUSION: Ro exerted inhibitory effect on cell proliferation induced by FFDP.

Animals↗
PubMed1997

[Effects of calcium inhibitor on hydrogen peroxide-induced damage and calcium influx in bovine aortic endothelial cells in culture].

Hydrogen peroxide(H2O2)-induced cell damage and Ca2+ influx into bovine aortic endothelial cells (BAEC) were investigated. Our data suggested that H2O2 could dose- and time-dependently induce damage in cultured BAEC assessed by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide(MTT) assay and increase malondialdehyde (MDA) production, which reflects the level of lipid peroxidation. Exposure of BAEC to H2O2 (100 mumol.L-1) caused significant increase in intracellular free calcium ([Ca2+]i) within 6 min, suggesting that the increase of [Ca2+]i might implicate in H2O2-induced cell damage. The calcium inhibitor nifedipine was found to dose-dependently decrease the increase of [Ca2+]i caused by H2O2 and protect BAEC against H2O2-induced damage reflected by significant decrease of MDA production and increase of MTT value. These results indicate that overload of calcium might be responsible to some extent causing oxidative damage to cells.

Animals↗
PubMed1997

[Investigation on hepatitis G virus (HGV) infection among different populations in Shenzhen].

A reverse transcription polymerase chain reaction assay with nested primers (RT-nested PCR) deduced from the 5' untranslated region of HGV genome was established to detect HGV RNA. By using this assay, we tested the serum samples of 106 paid blood donors, 80 intravenous drug users and 168 cases with viral hepatitis in Shenzhen, China. The positive rates of HGV RNA were 8.5%, 46.3% and 7.7%, respectively. The positive rates of HGV RNA in 61 cases with chronic hepatitis B and 33 cases with chronic hepatitis C were 8.2% and 21.2%. Among the 33 cases with chronic hepatitis C, the positive rate of HGV RNA in 15 cases infected with HCV by blood or blood products was 40.0%, compared with 1.7% in 18 cases without exposure to blood or blood products (P<0.05). The results of this study suggest that HGV infection is common in paid blood donors; the intravenous drug user is the population at high risk for HGV infection; the patients with post-transfusion chronic hepatitis C are often supperinfected with HGV.

Adult↗
PubMed1997

Studies of esophageal balloon cytology in Linxian, China.

Esophageal cancer is the second leading cause of cancer death in China. Esophageal cancer has a very poor prognosis, principally because most tumors are asymptomatic until they are unresectable. Esophageal balloon cytology is an early detection method developed by Chinese scientists to identify resectable early cancers and precursor lesions. Previous studies have reported high sensitivities for detecting esophageal cancer in symptomatic patients. The current report describes several studies evaluating this diagnostic technique in asymptomatic individuals. A comparison of Chinese and U. S. cytological diagnoses of the same esophageal samples showed that the Chinese categories of precancerous neoplasia were more inclusive than the corresponding U. S. categories. Comparisons of both Chinese and U. S. cytological diagnoses with concurrent histological findings showed low (14-36%) sensitivities for the cytological detection of biopsy-proven cancers. Prospective follow-up studies of several screened cohorts showed a consistent progression of risk for developing esophageal cancer with increasing severity of initial cytological diagnosis. These preliminary studies suggest that esophageal balloon cytology is a useful technique that can benefit from additional research to improve its optimal performance.

Adult↗
PubMed1997

[Intervention approach and its effect on lowering mortality of ectopic pregnancy in Shanghai].

OBJECTIVE: To explore an effective intervention approach to lower the mortality of ectopic pregnancy. METHODS: We monitored the mortality of ectopic pregnancy during 1987-1995 in Shanghai and experts' audit, focusing on the causes of death from ectopic pregnancy and combining official administration with intervention approach in medical institutions. RESULTS: Misdiagnosis and patient's delay to hospital were the causes of death from ectopic pregnancy. There were 523,299 live births in Shanghai from 1987 to 1989, in which 23 cases died from ectopic pregnancy, with a mortality of 4.40/100,000. After implementing the intervention approach, during 1990-1995, 14 cases of the total 625,206 nancies live birth died from ectopic pregnancy, with a mortality of 2.24/100,000, as compared the two, P < 0.05. Accordingly, ectopic pregnancy as the cause of maternal death dropped from the first leading cause to the fourth. CONCLUSION: Intensive health care education in masses, medical staffs' awareness to ectopic pregnancy, and intervention, early hospitalization, early diagnosis and early therapy can lower the mortality of ectopic pregnancy.

Adult↗
PubMed1996

BaeI, another unusual BcgI-like restriction endonuclease.

BcgI and BcgI-like restriction endonucleases have a very distinct characteristic which causes them to differ from the other classified restriction enzymes; they all cleave double-stranded DNA specifically on both sides of the recognition sequence to excise a short DNA fragment including the recognition sites. Here we report a new BcgI-like restriction endonuclease, BaeI, isolated from Bacillus sphaericus. Like BcgI, BaeI also cleaves double-stranded DNA on both strands upstream and downstream of its recognition sequence (10/15)ACNNNNGTAYC(12/7). There are two dominant polypeptides in the final preparation of BaeI with molecular masses of approximately 80 and 55 kDa. Both are slightly larger than the two BcgI subunits. BaeI requires both Mg2+ and AdoMet to cleave DNA. Accompanying bilateral cleavage activity, the heteromeric BaeI also has an N6-adenine methyltransferase activity which modifies the symmetrically located adenines within its recognition sequence.

Bacillus↗
PubMed1996

A novel ligand blot assay detects different hyaluronan-binding proteins in rat liver hepatocytes and sinusoidal endothelial cells.

We have developed a sensitive ligand blot assay to detect hyaluronan (HA) binding proteins in cell extracts using 125I-HA. Samples to be tested are electrophoresed using standard, nonreducing SDS-PAGE conditions, electro-transferred to nitrocellulose then blocked in buffer containing Tween 20. After incubation with 125I-HA the nitrocellulose is washed and HA-binding proteins are detected by autoradiography. This method was used to detect different HA-binding proteins in isolated rat liver cell preparations. Two HA-binding bands of 175 kD and 350 kD were detected in sinusoidal endothelial cells. Both bands were competed virtually 100% with nonlabeled HA. Using rat hepatocytes, the assay detected major bands at 85 kD and 180 kD. In addition, histones present in both cell types were readily detected in the low MW region. Thus, two different liver cell types show different HA-binding patterns. The blocking procedure is critical for successful renaturation of HA-binding activity, since substitution of BSA for Tween 20 did not result in detectable 125I-HA-binding. This ligand blot assay will be a powerful tool to detect HA-binding proteins in various other tissues and cell types.

Animals↗
PubMed1996

Histomorphometric study on germ cell differentiation of unilateral cryptorchidism in the immature pig.

Early spermatogenesis from gonocytes to A-type spermatogonia is inhibited in boys with cryptorchidism. Histological lesions in the undescended testes (UDT) are presumably secondary to the extrascrotal position. The purpose of this study is to determine the abnormalities in number and maturation of germ cells in pigs with undescended testes and to examine the effect of UDT location on early germ cell differentiation. Testicular biopsies from 4-week-old pigs with natural unilateral cryptorchidism (n = 20) were divided into three groups: (1) intraabdominal testes, (2) superficial inguinal pouch testes, and (3) contralateral descended testes (CDT). The testis weight (P < .01) and the area of circular cross-section of the seminiferous tubules (P < .05) in intraabdominal testes was lower than in CDT. The number of germ cells (per tubular cross-section) (P < .05) and A-type spermatogonia (P < .05) in intraabdominal and inguinal testes was significantly lower than in CDT. In contrast, the number of gonocytes in intraabdominal testes was similar to that in CDT. The number of Sertoli cells was similar in the three groups. These results demonstrate that defective transformation of gonocytes to A-type spermatogonia in pigs is similar to that observed in boys with unilateral cryptorchidism. The different locations of UDT in the pig are correlated with the degree of impaired spermatogenesis.

Animals↗
PubMed1996

Unfolding and refolding of the N-terminal fragments of staphylococcal nuclease R in guanidine hydrochloride.

The conformational and activity changes of a family of peptide fragments of staphylococcal nuclease R, which extend from residues -6 to 102, -6 to 110, -6 to 121, -6 to 135, and -6 to 141, during unfolding and refolding in different concentrations of guanidine hydrochloride have been studied. The studies indicate that the conformational stability in guanidine hydrochloride solution of the N-terminal fragment increases with increasing chain length, and that interaction and recognition between amino acid residues which are related to formation of the native conformation also increase with growth of the peptide chain, but such interaction becomes effective only when the polypeptide chain reaches a certain length. The changes in conformation and catalytic activity of the N-terminal fragments during unfolding and refolding demonstrate that conformational adjustments are necessary during chain elongation to generate the native conformation of a biologically active protein.

Guanidine↗
PubMed1996

Scanning electron microscopy shows inhibited gubernacular development in relation to undescended testes in oestrogen-treated mice.

The morphological relationship between transabdominal testicular descent and the 'swelling reaction' of the gubernaculum was investigated in oestrogen-treated fetal mice by using scanning electron microscopy (scanning EM). In addition, flutamide was also administered to pregnant mice to determine whether androgens cause gubernacular growth and transabdominal testicular descent in offspring. In oestrogen-treated fetal mice, scanning EM showed that both the gubernacular 'swelling reaction' and transabdominal testicular descent were inhibited, in addition to inhibition of Müllerian duct regression. The gubernaculum showed a flat, thin bulb (widest diameter 0.25 +/- 0.04 mm) and an elongated cord (1.28 +/- 0.41 mm) after oestrogen treatment in utero, which was significantly different in appearance from that in normal control mice (width 0.44 mm +/- 0.06 mm, p < 0.001; length 0.27 +/- 0.19 mm, p < 0.0001). However, flutamide-treated mice showed much more normal gubernacular enlargement and transabdominal testicular descent. The width of the gubernacular bulb after flutamide exposure was 0.44 +/- 0.05 mm, which was comparable to that in control animals; the length of the intra-abdominal gubernaculum (0.44 +/- 0.15 mm) was slightly longer than in controls (p < 0.02). These results suggest that both the swelling reaction of the gubernaculum and transabdominal testicular migration are blocked by prenatal exposure to oestrogen. However, oestrogen exposure of the fetus does not block the swelling reaction of the gubernaculum by acting as an antiandrogen.

Androgen Antagonists↗
PubMed1996

Salivary duct determination in Drosophila: roles of the EGF receptor signalling pathway and the transcription factors fork head and trachealess.

Organogenesis in Drosophila embryos begins at 4-5 hours of development as the expression of organ-specific genes is initiated. The salivary primordium, which occupies the ventral epidermis of parasegment 2, is among the earliest to be defined. It is soon divided into two distinct regions: the more dorsal pregland cells and the more ventral preduct cells. We show that it is the opposing activities of the Drosophila EGF receptor (DER) signaling pathway and the Fork head transcription factor that distinguish these cell types and set up the boundary between them. DER signaling acts ventrally to block fork head expression in the preduct cells, thereby restricting gland identity to the more dorsal cells. Fork head in turn blocks expression of duct-specific genes in the pregland cells, thereby restricting duct identity to the more ventral cells. A third regulatory activity, the Trachealess transcription factor, is also required to establish the identity of the preduct cells, but we show that it acts independently or downstream from the DER:fork head confrontation. In trachealess mutants, subdivision of the salivary primordium occurs normally and the dorsal cells form glands, but the ventral cells are undetermined. We present a model proposing that trachealess is the crucial duct-specific gene that Fork head represses to distinguish pregland from preduct cells.

Animals↗