Biomedical subjects

H Zhou

Publications and source records attributed to H Zhou.

At least 559 records · Page 31Linked to original sources

PubMed1996

Regulation of tissue-type plasminogen activator and plasminogen activator inhibitor type-1 in cultured rat Sertoli and Leydig cells.

New data are provided to show that (i) rat Sertoli cells produce two types of plasminogen activators, tissue type (tPA) and urokinase type (uPA), and a plasminogen activator inhibitor type-1 (PAI-1); (ii) both tPA (but not uPA) and PAI-1 secretion in the culture are modified by FSH, forskolin, dbcAMP, GnRH, PMA and growth factors (EGF and FGF), but not by hCG and androstenedione (delta 4); (iii) in vitro secretion of tPA and PA-PAI-1 complexes of Sertoli cells are greatly enhanced by presence of Leydig cells which produce negligible tPA but measurable PAI-1 activity; (iv) combination culture of Sertoli and Leydig cells remarkably increases FSH-induced PAI-1 activity and decreases hCG- and forskolin-induced inhibitor activity as compared with that of two cell types cultured alone. These data suggest that rat Sertoli cells, similar to ovarian granulosa cells, are capable of secreting both tPA and uPA, as well as PAI-1. The interaction of Sertoli cells and Leydig cells is essential for the cells to response to hormone stimulation for tPA and PAI-1 secretion.

Animals↗

PubMed1996

Modeling conception as an aggregated Bernoulli outcome with latent variables via the EM algorithm.

We describe a general method for analyzing aggregated Bernoulli outcomes. The research is motivated by an epidemiological reproductive study where the outcome was whether pregnancy was detected in a woman's particular menstrual cycle and the Bernoulli "trials" corresponded to days with intercourse during the cycle. Each cycle is either "viable" or not, i.e., is or is not susceptible to conception. We develop an EM algorithm approach to maximizing the observed-data pseudo-likelihood, based on a set of unobservable latent outcomes linked to the specific days with intercourse. This method is flexible in that it allows one to model effect of covariates on the susceptibility factor and on the latent outcomes. Application of the method to fertility studies enables one to investigate covariates with a long-term or transient effect on the daily conception probability. A complication is that most couples contribute more than one cycle in a prospective study. A generalized estimating equation approach adjusts for the dependency among outcomes within individual couples. The method can be applied in any setting where dependency among Bernoulli trials is induced by a susceptibility factor and the trial outcomes are only observable in the aggregate.

Algorithms↗

PubMed1996

[Immunotherapy of primary habitual abortion].

OBJECTIVE: To investigate whether different number of times of immunization and different immunogens have any effect on the outcome of pregnancy in patients with history of primary habitual abortion. METHODS: 38 cases of pregnant women with history of primary habitual abortion immunized with lymphocytes were analysed retrospectively. RESULTS: The results showed that the successful pregnancy rate was 87.5% (14/16) in the women immunized two times and was 86.4% (19/22) in the women immunized four times. There was no significant difference between the two groups. The successful pregnancy rate was 84.2% (16/19) in women immunized with their husbands' lymphocytes and 89.5% (17/19) in women immunized with donors' lymphocytes. There was also no significant difference between the two groups. CONCLUSIONS: In order to prevent hematogenous infection, active immunization could be reduced from four to two times and the immunogens may be selected from the husband or from healthy donor.

Abortion, Habitual↗

PubMed1996

[Relationship between SCE points and G-banding location in patients with nasopharyngeal carcinoma].

Using a technique for simultaneous demonstration of G bands and SCE, we analyzed the SCE frequencies, cell cycle kinetics, distribution of SCE points and "hot spots" which correlate with fragile sites, proto-oncogenes locus in cultured peripheral blood lymphocytes in 20 untreated patients with nasopharyngeal carcinoma (NPC). The SCE frequencies were found to be higher in patients as compared with controls (P < 0.01). The SCE points of patients were significantly higher than those of controls in chromosome 1,2,3,4,5,7,8,12,13,14,17 (P < 0.05), indicating the chromosome instability of NPC patients. We identified 17 points as high frequency SCE hot spots, and found that 29.41% SCE hot spots fragile sites and proto-oncogenes were localized at the same bands. The distribution of SCE points and chromosome structure were discussed.

Adult↗

PubMed1996

[Clinical and experimental study on effects of yinchen wuling powder in preventing and treating hyperlipoproteinemia].

Sixty cases with hyperlipoproteinemia (30 cases each group) were observed. The total effective rate of the treated group with Yinchen Wuling Powder was 93.3%. And that of the control group with Gynostemma pentophyllum capsule was 86.7%. The result revealed that significant difference existed between the above-mentioned two groups (P < 0.01). According to the animal experiment, on both prevention and treatment, this recipe could inhibit the increase of the hyperlipemia model rat's serum TCh, TG, LDL-C and the ratio of LDL-C/HDL-C (P < 0.01). Besides, this recipe had the effect of marked antioxidation. It could reduce the level of peroxidative lipids, and strengthen the glutathion peroxidase activities.

Animals↗

PubMed1996

[Twenty-years health surveillance of workers in dipterex packaging].

Data of health surveillance from 1970 to 1989 for the workers employed in dipterex packaging were collected and statistically analyzed with a microcomputer by scoring their whole blood choline esterase activities and symptoms and signs. Results showed working environment improved and air pollution and absorption of pollutants via skin decreased with technology innovation and longterm hygienic supervision, monitoring and health surveillance in the factory. Incidence of dipterex poisoning in workers employed in the department of pesticide packaging lowered significantly, from 25.26% in the early 1970's to 5.17% in late 1970's and to 1.85% during 1980's, with periodical physical examinations for them, and timely management of the patients with poisoning and the cases at high risk.

Adolescent↗

PubMed1996

[Impact of platelet derived growth factor in the glomeruli of active lupus nephritis].

Platelet derived growth factor (PDGF) possesses diverse biological activities and plays an important role in the pathogenesis of glomeruli nephritis. In order to elucidate the relationship between PDGF and the disease activation in lupus nephritis, PDGF was observed in renal biopsy specimen from 9 cases of lupus nephritis (7 cases with active and 2 cases with inactive lesions) by immunohistochemistry using 4-layer PAP method. The mRNA expression of PDGF-A and -B chain, and the receptor of PDGF-B were analyzed by RT-PCR. It was found that the levels of mRNA expression of PDGF and its receptor were much higher in patients with active lesions in glomeruli as compared with those without active lesions, there changes were paralleled with the degree of hematuria in these patients. Noted that there was no correlation between the expression of PDGF and the cellular proliferation in glomeruli of lupus nephritis. These results indicate that PDGF is a critical mediator for inducing active lesion in glomeruli of lupus nephritis. The effect of PDGF antagonist in the regulation of glomerular damage in lupus nephritis need to further elucidate.

Adolescent↗

PubMed1996

[Folk medicine of the Qiang nationality].

Based on a two-year investigation of folk medicine of the Qiang Nationality, systematic studies have been made on its formation and development, specific methods of physical therapy and experiences and features of clinical application.

China↗

PubMed1996

[Analysis of cinnamic acid in storax and its original plant by HPLC].

The contents of free and hydrolytic cinnamic acid in storax and its original plant (Liquidambar orientalis) were determined by high performance liquid chromatography, and the chromatographic behaviors were studied. In styrax gummi, the contents of free and hydrolytic cinnamic acid were 7.03% and 25.26% respectively; and in its original plant, they were 0.3% evenly.

Chromatography, High Pressure Liquid↗

PubMed1995

NMR studies of the phosphotransfer domain of the histidine kinase CheA from Escherichia coli: assignments, secondary structure, general fold, and backbone dynamics.

Multidimensional heteronuclear NMR techniques were applied to study the phosphotransfer domain, residues 1-134, of the histidine kinase CheA, from Escherichia coli, which contains the site of autophosphorylation, His48. Assignments of the backbone amide groups and side chain protons are nearly complete. Our studies show that this protein fragment consists of five alpha-helices (A-E) connected by turns. Analysis of NOE distance restraints provided by two-dimensional (2D) 1H-1H and three-dimensional (3D) 15N-edited NOESY spectra using model building and structure calculations indicates that the five helices form an antiparallel helix bundle with near-neighbor connectivity. The amino-terminal four helices are proposed to be arranged in a right-handed manner with helix E packing against helices C and D. From ideal hydrophobic helical packing and structure calculations, the site of autophosphorylation, His48, is nearly fully exposed to the solvent. We measured the NMR relaxation properties of the backbone 15N nuclei using inverse detected two-dimensional NMR spectroscopy. The protein backbone dynamics studies show that CheA1-134 is formed into a tight and compact structure with very limited flexibilities both in helices and turns. Structural implications of titration and phosphorylation experiments are briefly discussed.

Amino Acid Sequence↗

PubMed1995

Nuclear magnetic resonance assignments and global fold of a CheY-binding domain in CheA, the chemotaxis-specific kinase of Escherichia coli.

CheA is the histidine autokinase in the Escherichia coli chemotaxis signal transduction pathway responsible for coupling of signals received by transmembrane receptors to the response regulators CheY and CheB. Here NMR spectroscopy is used to study a 14 kDa fragment of CheA, residues 124-257, that binds the response regulator CheY. Backbone atom resonance assignments were obtained by analysis of 3D HNCACB, 3D CBCA(CO)NH, and HNCO spectra, whereas side-chain assignments were obtained primarily by analysis of 3D H(CCO)NH, 3D C(CO)NH, 3D HCCH-TOCSY, and 3D 1H, 15N TOCSY-HSMQC spectra. NOE cross peak patterns and intensities as well as torsion angle restraints were used to determine the secondary structure, and a low-resolution structure was calculated by hybrid distance-geometry simulated annealing methods. The CheA124-257 fragment consists of four antiparallel beta strands and two helices, arranged in an "open-faced beta-sandwich" motif, as well as two unstructured ends that correspond to domain linkers in the full-length protein. The 15N-1H correlation spectrum of 15N-labeled CheA124-257 bound to unlabeled CheY shows specific localized changes that may correspond to a CheY-binding face on CheA.

Amino Acid Sequence↗

PubMed1995

Tyrosine kinase inhibitors. 5. Synthesis and structure-activity relationships for 4-[(phenylmethyl)amino]- and 4-(phenylamino)quinazolines as potent adenosine 5'-triphosphate binding site inhibitors of the tyrosine kinase domain of the epidermal growth factor receptor.

A series of 4-substituted quinazolines and related compounds have been prepared and evaluated for their ability to inhibit the tyrosine kinase activity of the epidermal growth factor receptor on a phospholipase C-gamma 1-derived substrate. The results show a narrow structure-activity relationship (SAR) for the basic ring system, with quinazoline being the preferred chromophore and benzylamino and anilino the preferred side chains. In the 4-anilino series, substitution on the 3-position of the phenyl ring with small lipophilic electron-withdrawing groups provided analogues with enhanced potency. Two series of compounds [4-(phenylmethyl)amino and 4-(3-bromophenyl)amino] were studied to determine SARs for quinazoline substituents. In the more active 4-(3-bromophenyl)amino series, electron-donating groups (NH2, OMe) at the 6- or 7-position increased activity, in a pattern consistent with a requirement for high electron density in the vicinity of the 8-position of the quinazoline ring. The 6,7-dimethoxy derivatives were the most effective in both series, with the 4-(3-bromophenyl)amino derivative (3) having an IC50 of 0.029 nM, making it by far the most potent reported inhibitor of the tyrosine kinase activity of the epidermal growth factor receptor enzyme.

Adenosine Triphosphate↗

PubMed1995

p53 gene mutations with chromosome 17 abnormalities in chronic myelogenous leukemia blast crisis patients persist in long-term cell lines but may be acquired in acute myeloid leukemia cells in vitro.

Altered p53 tumor suppressor genes have been described in various human malignancies, including in chronic myelogenous leukemias (CML) and acute myelogenous leukemias (AML), as well as their derivative cell lines. It has been proposed that this gene mutation may be less frequent in myeloid leukemia patients than in myeloid leukemia cells lines and that the latter acquire these mutations during growth in vitro. We investigated this possibility by studying p53 gene alterations in matched samples of fresh leukemic cells and their respective derivative cell lines obtained from two CML blast crisis and one AML patient. No gross structural abnormalities were detected in the p53 gene in any of the samples analyzed. Discrete mutations in the gene in the two CML blast crisis samples and in all three derivative cell lines were, however, detected by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analyses and DNA sequencing. Cytogenetic analyses revealed either numerical or structural, as well as numerical, abnormalities of chromosome 17 in their karyotypes. Cells from the two CML blast crisis patients had two different mutations which were maintained as the sole mutations in the cell lines. The mutation detected in the AML cell line was, however, not detectable in the parental fresh leukemic cells. Our findings demonstrate that p53 mutations and chromosome 17 abnormalities occurring in CML blast crisis patients persist in long-term cell lines but that mutations not detectable in AML patients may indeed be acquired in cell lines established from them in vitro.

Adult↗

PubMed1995

Introduction of a loss-of-function point mutation from the SH3 region of the Caenorhabditis elegans sem-5 gene activates the transforming ability of c-abl in vivo and abolishes binding of proline-rich ligands in vitro.

We have introduced two loss-of-function point mutations from highly conserved regions of the src homology 3 (SH3) domains of the Caenorhabditis elegans sem-5 gene into the SH3 domain of the murine type IV c-abl tyrosine kinase proto-oncogene. One of the mutations, P131L, activated abl to transform fibroblasts while the other, G128R, did not. When combined with independent activating mutations in the c-abl kinase domain or NH2-terminus, the G128R mutation blocked transformation by the double mutant, suggesting that the G128R mutant was unable to transform cells for trivial reasons. The c-Abl G128R mutant, like wild type c-Abl protein, was localized to the nucleus and actin cytoskeleton and had normal tyrosine kinase activity in vitro, while the transforming c-Abl P131L protein was localized exclusively to the cytoplasm and exhibited decreased in vitro kinase activity. By real-time biospecific interaction analysis, the wild type Abl SH3 domain bound to two proteins containing proline-rich motifs with dissociation constants of 0.2 and 17 microM; the G128R mutant bound with 50-fold lower affinity, and no binding was detected by the P131L mutant. Both mutations completely abolished binding of the Abl SH3 domain to proline-rich target proteins in a filter-binding assay. These results suggest that the transforming activity of Abl is regulated in vivo by an inhibitor protein which associates with the SH3 domain via a proline-rich sequence.

3T3 Cells↗

PubMed1995

Tumor necrosis factor alpha facilitates nuclear actions of retinoic acid to regulate expression of the alkaline phosphatase gene in preosteoblasts.

This study examines the molecular mechanisms of interaction between tumor necrosis factor alpha (TNF alpha) and retinoic acid on the expression of the alkaline phosphatase gene by rat clonal preosteoblastic cells. In this cell line, alkaline phosphatase mRNA was not constitutively expressed but was progressively induced by treatment with 1 microM retinoic acid, detectable by 6 h. Combining retinoic acid with 0.6 nM TNF alpha resulted in alkaline phosphatase mRNA appearing by 2 h, as well as enhanced expression above that observed with retinoic acid alone at 6, 12, and 24 h. Nuclear run-on analysis showed constitutive transcription of the alkaline phosphatase gene in control and TNF alpha-treated cells. At 4 h, retinoic acid, alone or combined with TNF alpha, increased alkaline phosphatase gene transcriptional rate by 2-fold. However, at 24 h, while no retinoic acid effect was retained, retinoic acid plus TNF alpha resulted in a 5-fold increase in alkaline phosphatase transcriptional rate. Examination of the distribution of nuclear alkaline phosphatase mRNA demonstrated that pre-spliced precursor mRNA was localized to the nuclear matrix in control and all treatment groups. Retinoic acid caused a time-dependent accumulation of mature, spliced alkaline phosphatase mRNA located in the non-matrix and cytoplasmic fractions, implying a post-transcriptional action of retinoic acid in nuclear processing and nucleocytoplasmic transport. Adding TNF alpha with retinoic acid greatly enhanced this effect, which was observed after 4 h, prior to any detectable interaction between TNF alpha and retinoic acid on gene transcription. In sharp contrast, only a negligible amount of nuclear processing occurred in control and TNF alpha-treated cells. This study reveals distinct interactions between TNF alpha and retinoic acid at post-transcriptional as well as transcriptional levels to regulate expression of the alkaline phosphatase gene in preosteoblasts.

Alkaline Phosphatase↗

PubMed1995

CREB as a memory modulator: induced expression of a dCREB2 activator isoform enhances long-term memory in Drosophila.

Genetic studies of memory formation in Drosophila have revealed that the formation of a protein synthesis-dependent long-term memory (LTM) requires multiple training sessions. LTM is blocked specifically by induced expression of a repressor isoform of the cAMP-responsive element-binding protein (CREB). Here, we report an enhancement of LTM formation after induced expression of an activator isoform of dCREB2. Maximum LTM is achieved after one training session, and its formation depends on phosphorylation of the activator transgene. A model of LTM formation based on differential regulation of CREB isoforms is proposed.

Animals↗

PubMed1995

Modulation of ADP-stimulated inositol phosphate metabolism in rat alveolar macrophages by oxidative stress.

The present study examined alterations of adenosine-5-diphosphate (ADP)-stimulated inositol phosphate (IP3) metabolism and the respiratory burst of rat alveolar macrophages (AM) under oxidant stress using the model oxidant, tert-butyl hydroperoxide (tBOOH). Isolated AM were maintained in a system with an air-liquid interface, which approximates the lung environment. tBOOH produced a dual effect on the ADP-stimulated respiratory burst of these AM. Pretreatment of these AM with 50 microM tBOOH for 15 min led to a significant enhancement of the respiratory burst while significant inhibition was observed with 200 microM tBOOH. Treatment of AM with 100 microM ADP led to a significant increase in the generation of IP3, reaching a maximum at 30 s. In contrast, treatment of AM with 50 or 200 microM tBOOH did not stimulate IP3 generation during a 15-min period. Pretreatment of AM with 50 microM tBOOH for 15 min had no effect on ADP-stimulated IP3 generation. Preincubation with 200 microM tBOOH significantly inhibited generation of IP3 in response to ADP stimulation; however, this probably did not contribute to inhibition of the respiratory burst. The results suggest that production of IP3 may participate in stimulation of the respiratory burst by ADP but that enhancement of the respiratory burst by 50 microM tBOOH probably did not involve alteration of IP3 production.

Adenosine Diphosphate↗

PubMed1995

Retinoic acid stimulates glucose transporter expression in L6 muscle cells.

Factors that regulate the tissue specific and developmental expression of the GLUT4 gene, whose transcribed protein is primarily responsible for mediating insulin stimulated glucose transport, are poorly defined. In this study we examined the effects of retinoic acid, a circulating factor that can promote cellular differentiation, on glucose uptake and glucose transporter expression in cultured L6 muscle cells. At the myoblast stage, treatment with 1 microM retinoic acid for 24 h increased both 1 h and 8 h insulin stimulated uptake of 2-deoxyglucose by more than twofold. A dose and time dependent effect of retinoic acid on 8 h insulin stimulated 2-deoxyglucose uptake was observed at both the myoblast and myocyte stage. Comparatively little effect from retinoic acid treatment was found on basal uptake at either stage. In myoblast cells, retinoic acid increased the content of GLUT4 mRNA in a dose and time dependent manner, an effect that was partially attenuated by insulin. In myocytes retinoic acid increased GLUT4 mRNA levels to 2.3 times basal. Nuclear run-on studies indicate that the increased GLUT4 mRNA represents enhanced transcriptional activity. The results suggest a role for retinoic acid in regulation of expression of the GLUT 4 gene in muscle cells.

Analysis of Variance↗