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Biomedical subjects

J Zhou

Publications and source records attributed to J Zhou.

At least 541 records · Page 30Linked to original sources
PubMed1998

Calcium is required in reassembly of bovine papillomavirus in vitro.

Papillomaviruses are small DNA viruses which infect and induce benign warts and sometimes malignant tumours in the epithelium of the skin or mucosa. The viruses do not replicate in conventional tissue culture systems and little is known about the requirements for virus assembly. We investigated the effect of ethylene glycol-bis(aminoethyl ether)-tetraacetic acid (EGTA) and dithiothreitol (DTT) treatment on the stability of bovine papillomavirus type 1 (BPV-1) particles in vitro. Removal of calcium ions by 11 mM EGTA at pH 8.0 together with reduction of disulfide bonds by 15 mM DTT destabilized BPV particles. Electron microscopy examination of treated particles showed that the BPV particles had been disrupted to capsomeres. Addition of exogenous calcium ions to the disruption buffer prevented virus destabilization. Adding calcium to the disrupted BPV particles resulted in the reassembly of disrupted particles. The reassembled particles were morphologically similar to intact BPV virions. We further quantified the efficiency of reassembly by focus formation assay. We recorded 500-fold less infectivity for reassembled BPV and 4-fold less haemagglutination activity compared to untreated BPV, pointing towards a decrease in the amount of reassembled particles recovered.

Animals↗
PubMed1998

A nitrilase-like protein interacts with GCC box DNA-binding proteins involved in ethylene and defense responses.

Ethylene-responsive element-binding proteins (EREBPs) of tobacco (Nicotiana tabacum L.) bind to the GCC box of many pathogenesis-related (PR) gene promoters, including osmotin (PR-5). The two GCC boxes on the osmotin promoter are known to be required, but not sufficient, for maximal ethylene responsiveness. EREBPs participate in the signal transduction pathway leading from exogenous ethylene application and pathogen infection to PR gene induction. In this study EREBP3 was used as bait in a yeast two-hybrid interaction trap with a tobacco cDNA library as prey to isolate signal transduction pathway intermediates that interact with EREBPs. One of the strongest interactors was found to encode a nitrilase-like protein (NLP). Nitrilase is an enzyme involved in auxin biosynthesis. NLP interacted with other EREBP family members, namely tobacco EREBP2 and tomato (Lycopersicon esculentum L.) Pti4/5/6. The EREBP2-EREBP3 interaction with NLP required part of the DNA-binding domain. The specificity of interaction was further confirmed by protein-binding studies in solution. We propose that the EREBP-NLP interaction serves to regulate PR gene expression by sequestration of EREBPs in the cytoplasm.

Amino Acid Sequence↗
PubMed1998

Killing of Staphylococcus aureus by C-8-methoxy fluoroquinolones.

C-8-methoxy fluoroquinolones were more lethal than C-8-bromine, C-8-ethoxy, and C-8-H derivatives for Staphylococcus aureus, especially when topoisomerase IV was resistant. The methoxy group also increased lethality against wild-type cells when protein synthesis was inhibited. These properties encourage refinement of C-8-methoxy fluoroquinolones to kill staphylococci.

Anti-Bacterial Agents↗
PubMed1998

Function of protonatable residues in the flagellar motor of Escherichia coli: a critical role for Asp 32 of MotB.

Rotation of the bacterial flagellar motor is powered by a transmembrane gradient of protons or, in some species, sodium ions. The molecular mechanism of coupling between ion flow and motor rotation is not understood. The proteins most closely involved in motor rotation are MotA, MotB, and FliG. MotA and MotB are transmembrane proteins that function in transmembrane proton conduction and that are believed to form the stator. FliG is a soluble protein located on the cytoplasmic face of the rotor. Two other proteins, FliM and FliN, are known to bind to FliG and have also been suggested to be involved to some extent in torque generation. Proton (or sodium)-binding sites in the motor are likely to be important to its function and might be formed from the side chains of acidic residues. To investigate the role of acidic residues in the function of the flagellar motor, we mutated each of the conserved acidic residues in the five proteins that have been suggested to be involved in torque generation and measured the effects on motility. None of the conserved acidic residues of MotA, FliG, FliM, or FliN proved essential for torque generation. An acidic residue at position 32 of MotB did prove essential. Of 15 different substitutions studied at this position, only the conservative-replacement D32E mutant retained any function. Previous studies, together with additional data presented here, indicate that the proteins involved in motor rotation do not contain any conserved basic residues that are critical for motor rotation per se. We propose that Asp 32 of MotB functions as a proton-binding site in the bacterial flagellar motor and that no other conserved, protonatable residues function in this capacity.

Aspartic Acid↗
PubMed1998

Effect of repeated stress on body weight and body composition of rats fed low- and high-fat diets.

Exposure to the moderate stressor of 3-h restraint for 3 consecutive days causes a temporary drop in food intake but a permanent reduction in body weight in adult rats. Young rats did not show the same response. Food intake of adult rats exposed to repeated restraint was significantly lower than that of controls for 4 days after the end of stress, and there was no rebound hyperphagia. Body weight remained significantly lower for at least 40 days after stress. When the rats were fed a high-fat diet of 80% chow and 20% vegetable shortening (48% kcal fat, 16% protein), lean body mass accounted for all of the weight loss in stressed rats. When the experiment was repeated with a purified high-fat diet containing corn oil and coconut oil as the source of fat (41% kcal fat, 16% protein), weight loss consisted of both lean and fat tissue. There were no sustained changes in single time point measures of corticosterone, insulin, or leptin that could account for the reduced body weight in these rats.

Aging↗
PubMed1998

Improved survival with resection after transcatheter arterial chemoembolization (TACE) for unresectable hepatocellular carcinoma.

AIM: This retrospective study was undertaken to analyze the outcome of hepatic resection in hepatocellular carcinomas (HCCs) that shrunk after transcatheter hepatic arterial chemoembolization (TACE) in 65 patients with unresectable HCCs between June 1987 and September 1996. MATERIALS AND METHODS: Among these 65 patients, the median diameter of the tumor was 9.9 cm (5.6-20.0) prior to the first TACE, after 1-6 times of TACE (median 3) the median tumor diameter reduced to 3.7 cm (1.9-12.5) prior to resection. The duration between the last TACE treatment and sequential resection varied from 1 to 9 months (median 2.5). Serum alpha-fetoprotein (AFP) levels were abnormal in 39 out of the 65 patients. In AFP producing HCCs, the AFP level returned to normal (</=20 microgram/l) in 14 out of 39 patients (35.9%). Hepatic segmentectomy, multiple hepatic segmentectomy or partial hepatic resection were performed in 61 patients, right hemihepatectomy in 1, left trisegmentectomy in 2, and left hemihepatectomy in 1. RESULTS: Tumor necrosis ranged from 40 to 100% and pathologically and complete tumor necrosis occurred in 11 patients (16.9%). Of 14 patients with AFP levels decreased to normal, 10 still had microscopic living tumor foci. The 1-, 3- and 5-year survival rates of the 65 patients were 80.0, 65.0 and 56.0% respectively. CONCLUSION: TACE treatment can provide a chance of tumor resection for those patients with initially judged unresectable HCCs, and liver resection should be performed when the tumor has shrunk to be resectable, even when the AFP level has returned to normal.

Adult↗
PubMed1998

Expression of heterogeneous nuclear ribonucleoprotein A2/B1 changes with critical stages of mammalian lung development.

Recent reports have demostrated a link between expression of members of the family of heterogeneous nuclear ribonucleoproteins (hnRNPs) and cancer. Overexpression of hnRNP A2/B1 correlated with the eventual development of lung cancer in three different clinical cohorts. We have studied the expression of hnRNP A2/B1 messenger RNA (mRNA) and protein during mammalian development. The expression of hnRNP A2/B1 mRNA and protein are parallel but change dynamically during critical periods in mouse pulmonary development. hnRNP A2/B1 is first detected in the lung in the early pseudoglandular period, peaks at the beginning of the canalicular period, and remains high during the saccular (alveolar) period. In mouse and rat, hnRNP A2/B1 expression is first evident in the earliest lung buds. As lung development progresses, the cuboidal epithelial cells of the distal primitive alveoli show high levels of the ribonucleoprotein, which is almost undetectable in the proximal conducting airways. The expression of hnRNP A2/ B1 is restricted in mature lung. Similar dynamic pattern of expression through lung development was also found in rat and human lung. Upregulated expression of hnRNP A2/B1 at critical periods of lung development was comparable to the level of expression found in lung cancers and preneoplastic lesions and is consistent with hnRNP A2/B1 overexpression playing an oncodevelopmental role.

Animals↗
PubMed1998

A leptin dose-response study in obese (ob/ob) and lean (+/?) mice.

This experiment determined the amount of leptin required to correct different abnormalities in leptin-deficient ob/ob mice. Baseline food intakes and body weights of lean (+/?) and obese (ob/ob) C57B1/6J mice were recorded for 7 days. An Alzet miniosmotic pump was placed in the peritoneal cavity of each mouse and delivered 0, 1, 2, 5, 10, or 42 microg/day human leptin for 7 days. In ob/ob mice, 2 microg leptin/day reduced food intake and body weight, and increased hypothalamic and brain stem serotonin concentrations. All fat pads were reduced 35-40% by 10 microg leptin/day, and liver weight, lipid, and glycogen decreased. Serum insulin and glucose were reduced in all leptin-treated ob/ob mice, and levels were normalized by 10 microg/day leptin. Low rectal temperatures of ob/ob mice were corrected by 10 and 42 microg/day leptin. These doses also increased brown adipose tissue uncoupling protein expression. The only responses in lean mice were a transient reduction in food intake and weight loss with 10 or 42 microg/day leptin. This study shows enhanced leptin sensitivity in ob/ob mice and suggests that increased temperature and sympathetic activity are indirect responses to high concentrations of protein.

Animals↗
PubMed1998

Androgen receptor gene expression in the primate ovary: cellular localization, regulation, and functional correlations.

Excess androgens are associated with a characteristic polyfollicular ovarian morphology; however, it is not known to what extent this problem is due to direct androgen action on follicular development vs. interference with gonadotropin release at the level of the pituitary or hypothalamus. To elucidate potential androgen effects on the ovary, we investigated the cellular localization of androgen receptor (AR) messenger ribonucleic acid (mRNA) in rhesus monkey using in situ hybridization. To investigate the regulation of ovarian AR gene expression, we compared the relative abundance of AR transcripts in monkeys during follicular and luteal phases of the menstrual cycle and in monkeys treated with testosterone. To assess potential functional consequences of AR expression in the primate ovary, we compared AR mRNA levels with indexes of follicular cell proliferation and apoptosis in serial sections from individual follicles. AR mRNA expression was most abundant in granulosa cells of healthy preantral and antral follicles in the primate ovary. Theca interna and stromal cells also expressed AR mRNA, but to a lesser degree than granulosa cells. No significant cycle stage effects were noted in AR mRNA levels; however, larger numbers of animals would be necessary to definitively establish a cycle stage effect. AR mRNA level was significantly increased in granulosa cells and was decreased in theca interna and stromal cells of testosterone-treated monkeys. Importantly, granulosa cell AR mRNA abundance was positively correlated with expression of the proliferation-specific antigen Ki-67 (r = 0.91; P < 0.001) and negatively correlated with granulosa cell apoptosis (r = -0.64; P < 0.001). In summary, these data show that primate ovary AR gene expression is most abundant in granulosa cells of healthy growing follicles, where its expression is up-regulated by testosterone. The positive correlation between granulosa AR gene expression and cell proliferation and negative correlation with programmed cell death suggests that androgens stimulate early primate follicle development.

Animals↗
PubMed1998

High mutation detection rate in the COL4A5 collagen gene in suspected Alport syndrome using PCR and direct DNA sequencing.

Approximately 85% of patients with Alport syndrome (hereditary nephritis) have been estimated to have mutations in the X chromosomal COL4A5 collagen gene; the remaining cases are autosomal with mutations in the COL4A3 or COL4A4 genes located on chromosome 2. In the present work, the promoter sequence and previously unknown intron sequences flanking exons 2 and 37 of COL4A5 were determined. Furthermore, intron sequences flanking the other 49 exons were expanded from 35 to 190 to facilitate mutation analysis of the gene. Using this information, all 51 exons and the promoter region were PCR-amplified and sequenced from DNA of 50 randomly chosen patients with suspected Alport syndrome. Mutations were found in 41 patients, giving a mutation detection rate of 82%. Retrospective analysis of clinical data revealed that two of the cases might be autosomal. Although it could not be determined whether the remaining seven cases (14%) were autosomal or X chromosome-linked, it is likely that some of them were autosomal. It is concluded that PCR amplification and direct DNA sequencing of the promoter and exons is currently the best procedure to detect mutations in COL4A5 in Alport syndrome.

Amino Acid Substitution↗
PubMed1998

Regulation of glutamine:fructose-6-phosphate amidotransferase by cAMP-dependent protein kinase.

Glutamine:fructose-6-phosphate amidotransferase (GFA) is the rate-limiting enzyme in hexosamine biosynthesis, an important pathway for cellular glucose sensing. Human GFA has two potential sites for phosphorylation by cAMP-dependent protein kinase A (PKA). To test whether GFA activity is regulated by cAMP-dependent phosphorylation, rat aortic smooth muscle cells were treated in vivo with cAMP-elevating agents, 10 micromol/l forskolin, 1 mmol/l 8-Br-cAMP, or 3-isobutyl-1-methylxanthine. All treatments resulted in rapid and significant increases (2- to 2.4-fold) in GFA activity assayed in cytosolic extracts. Maximal effects of forskolin were observed at 10 micromol/l and 60 min. Preincubation of cells with cycloheximide did not abolish the effect of forskolin. Incubation of cytosolic extracts at 37 degrees C for 10 min in a buffer without phosphatase inhibitors led to a 79% decrease of GFA activity. This loss of activity was inhibited by the addition of phosphatase inhibitors (5 mmol/l sodium orthovanadate, 50 mmol/l sodium fluoride, or 5 mmol/l EDTA, but not 100 nmol/l okadaic acid), suggesting that GFA undergoes rapid dephosphorylation by endogenous phosphatases. Purified GFA is phosphorylated in vitro by purified PKA, resulting in a 1.7-fold increase in GFA activity. Treatment of GFA with purified protein kinase C had no effect. We conclude that GFA activity may be modulated by cAMP-dependent phosphorylation.

Adenylyl Cyclases↗
PubMed1998

[The correlation between abusing alcohol and antioxidants, antioxidases].

OBJECTIVE: To study the correlation between abusing alcohol and antioxidants, antioxidases and oxygen free radical reaction. METHODS: We measured spectrophotometrically the plasma vitamin C(P-VC), plasma vitamin E(P-VE), plasma beta-carotene (P-beta-CAR) contents and erythrocyte superoxide dismutase (E-SOD), erythrocyte catalase (E-CAT), erythrocyte glutathione peroxidase (E-GSH-Px) activities in 194 male (40 years old) alcohol abusers and 50 male (40 years old) nondrinkers. RESULTS: The average P-VC, P-VE, P-beta-CAR contents and E-SOD, E-CAT, E-GSH-Px activities of the alcohol abuser group were lower than those of the nondrinker group. The P-VC, P-VE, P-beta-CAR contents and E-SOD, E-CAT, E-GSH-Px activities of the alcohol abusers decreased as the time and quantity of abusing alcohol increased. CONCLUSION: The oxygen free radical reaction in the alcohol abusers was pathologically exacerbated, and the balance between oxidation and antioxidation was serious imbalanced.

Adult↗
PubMed1998

[Changes in blood levels of nitric oxide, oxidation and lipoperoxidation in patients with silicosis].

OBJECTIVE: To explore the relationship between nitric oxide, oxidation, lipoperoxidation and silicosis. METHODS: Blood plasma levels of nitric oxide (P-NO), vitamin C (P-VC), vitamin E (P-VE), beta-carotene (P-beta-CAR), lipoperoxidase (P-LPO), and erythrocyte activities of superoxide dismutase (E-SOD), catalase (E-CAT), glutathione peroxidase (E-GSH-Px) and lipoperoxidase (E-LPO) were measured in 73 patients with silicosis and 60 healthy subjects. RESULTS: The average levels of P-VC, P-VE, P-beta-CAR, E-SOD, E-CAT and E-GSH-Px were significantly lower and the average levels of P-NO, P-LPO and E-LPO significantly increased in the silicosis with varied severity of the disease and lung function status more than in the controls. There was linear relationship between all the above indices and length of the disease. Stepwise regression analysis showed that the severity of the disease and lung function status correlated most closely with the levels of P-NO, P-VE, E-SOD and E-LPO. CONCLUSION: Metabolism of nitric oxide was abnormal, balance between oxidation and antioxidation was disturbed seriously, and oxidation and lipoperoxidation reaction pathologically exacerbated in the bodies of the patient with silicosis.

Adult↗
PubMed1998

[Studies on effects of cytokine released from alveolar macrophage induced by mineral dust on lung fibroblast].

OBJECTIVE: To understand the role of cytokine released from alveolar macrophage (AM) in lung fibrosis caused by mineral dust. METHODS: Rabbit's AM obtained by lavage was cultured with mineral dust in vitro. Activities of tumor necrosis factor (TNF) and interleukin 6 (IL-6) in its supernatant were determined with isotope labelling method and MTT colorimetry, respectively. Human fetal lung fibroblast WI-138 was cultured with this supernatant. Proliferation of fibroblast and synthesis of collagen were examined by 3H-thymidine (3H-TdR) and 14C-proline (14C-Pro) incorporation and its total hydroxyproline (HOP) level was analyzed by chloramine-T method. RESULTS: Proliferation of lung fibroblast and synthesis of collagen could be enhanced by the supernatant containing AM induced by quartz, asbestos and uranium mineral dust, with 3H-TdR incorporated counts per minute (cpm) of 6,584, 3,848 and 6,893 in the group of 100 micrograms 3H-TdR and 14C-Pro incorporated 27,952, 13,416 and 18,538 in the group of 200 micrograms respectively, which were significantly higher than those in the control group. Total HOP levels in the culture media for lung fibroblast enhanced by AM supernatant were 22.41, 24.00 and 21.39 micrograms/ml, respectively, and was significantly higher than that in the control group (12.91 micrograms/ml). Release of TNF and IL-6 could be stimulated by mineral dust, such as quartz, asbestos and uranium mineral dust, and their activities were significantly higher than those in the control group, with those of 1,396, 1,198 and 852 U/ml in TNF group and 1,336, 1511 and 1,335 U/ml in IL-6 group, respectively. Proliferation of lung fibroblast and synthesis of collagen could be inhibited by antibody against TNF and interferon-r (gamma), and the effect of the latter was weaker than that of the former on inhibition of fibroblast proliferation and the effect on collagen synthesis was just in the opposite direction. CONCLUSION: Lung fibrosis caused by mineral dust correlated with abnormal expression of TNF and IL-6. Antibody against TNF and gamma interferon could antagonize the effect of NTF and IL-6.

Animals↗
PubMed1998

[Repair of large articular cartilage defect of hip with allograft of skull periosteum].

It is very difficult to repair large articular cartilage defect of the hip. From May 1990 to April 1994, 47 hips in 42 patients of large articuler cartilage defects were repaired by allograft of skull periosteum. Among them, 14 cases, whose femoral heads were grade. IV necrosis, were given deep iliac circumflex artery pedicled iliac bone graft simultaneously. The skull periosteum had been treated by low tempreturel (-40 degrees C) before and kept in Nitrogen (-196 degrees C) till use. During the operation, the skull periosteum was sutured tightly to the femoral head and sticked to the accetabulum by medical ZT glue. Thirty eight hips in 34 patients were followed up for 2-6 years with an average of 3.4 years. According to the hip postoperative criteria of Wu Zhi-kang, 25 cases were excellent, 5 cases very good, 3 cases good and 1 case fair. The mean score increased from 6.4 before operation to 15.8 after operation. The results showed, in compare with autograft of periosteum for biological resurface of large articular defect, this method is free of donor-site morbidity. Skull periosteum allograft was effective for the treatment of large articular cartilage defects in hip.

Adolescent↗
PubMed1998

Production of longer acting tissue plasminogen activator of humans in milk of transgenic mice.

An exogenous gene was expressed in the mammary epithelium of transgenic mice in the hope that the encoded protein could be secreted into milk. The transgenic mice carrying the promoter and upstream regulatory sequences from the sheep BLG gene which were fused to cDNA encoding human tissue plasminogen activator (tPA) with its endogenous secretion signal sequence were generated. The hybrid genes were microinjected into mouse embryos. Two mice were identified as being transgenic by Southern blot. Milk obtained from lactating females contained biologically active tPA, and its concentration was calculated to be about 1.5 microg/ml. This result establishes the feasibility of secreting protein into the milk of transgenic animals for production of biologically active tPA proteins, and may provide a powerful method to produce such proteins on a large scale.

Animals↗
PubMed1998

[Significance of microvessel quantity in metastasis of invasive breast carcinoma].

Microvessel quantity(MVQ), expression of CD44V6 and EGFR were studied in 48 patients with invasive breast carcinoma by CD31 immunohistochemistry. Significant differences of MVQ, CD44V6 and EGFR were observed (P < 0.01) between the groups with and without metastasis. The results suggest that angiogeneses and activation of tumor metastasis associated gene play an important role in tumor metastasis.

Adult↗