Biomedical subjects

G Zhou

Publications and source records attributed to G Zhou.

At least 199 records · Page 11Linked to original sources

PubMed1996

Effects of angiotensin II and aldosterone on collagen gene expression and protein turnover in cardiac fibroblasts.

Earlier studies have demonstrated angiotensin II (AngII) and aldosterone (ALDO) each augment cultured adult rat cardiac fibroblast (CFb) collagen synthesis. Whether this involves type I collagen, the major structural protein of the myocardium, and represents a transcriptional event, is uncertain. Accordingly, the influence of AngII and ALDO on transcription and synthesis of fibrillar collagen and on collagenolytic activity was examined in cultured CFb maintained in serum-deprived media. Using concentrations for AngII (10(-7) M) or ALDO (10(-9) M), shown to influence collagen turnover in these cells, we found: a) total collagen synthesis was significantly (p < 0.05) increased (5.4 +/- 0.41 and 4.8 +/- 0.37 vs. control 3.1 +/- 0.55); b) type I collagen production (6590 +/- 710 and 6150 +/- 410 vs. control 4700 +/- 490 ng/mL) in the medium were significantly (p < 0.01) increased; c) type I collagen mRNA expression was also significantly (p < 0.01) increased by AngII (2.0 fold) and ALDO (1.8 fold) compared with control; d) AngII, but not ALDO, significantly (p < 0.05) decreased collagenolytic activity (0.5 fold) compared with control. Thus, AngII and ALDO each increase CFb type I collagen synthesis at the level of transcription and protein synthesis and AngII, but not ALDO, alters collagenolytic activity. Such hormonally mediated alterations in CFb collagen turnover may contribute to the adverse accumulation of fibrillar collagen found in the myocardium in various disease states, where circulating AngII and/or ALDO are increased.

Aldosterone↗

PubMed1996

Application of hemodilution in microsurgical free flap transplantation.

The intra-operative hemodilution and blood auto-transfusion is a blood-saving technique that can be performed when major blood loss is expected. The effects of this technique were studied in 30 microsurgical free flap transplantation patients. Between 400-600 ml blood was collected from the patients before surgery. The patients received dextran, a balanced salt solution, and glucose with the ratio of 3:1 to the collected blood volume, bleeding, and urine before the blood auto-transfusion. There were no significant changes in RBC, HCT, MCV, blood pressure, or heart rate. Of the 30 free flaps, 28 were successful with a 93.3% survival rate. The safety of intra-operative hemodilution and autologous blood transfusion in microsurgery as well as the effect of hemodilution on transplanted flap survival are discussed in this study.

Adult↗

PubMed1996

Over-production of the D1:2 protein makes Synechococcus cells more tolerant to photoinhibition of photosystem II.

Over-expression of the psbAIII gene encoding for the D1 protein (form II; D1:2) of the photosystem II reaction centre in the Synechococcus sp. PCC 7942 was studied using a tac promoter and the lacIQ system. Over-expression was induced with 40 microgram/ml IPTG in the growth medium for either 6 or 12 h at growth irradiance (50 mumol photons m-2 s-1). This treatment doubled the amount of psbAII/III mRNA and the D1:2 protein in membranes but decreased the amount of psbAI messages and the D1:1 protein. The total amount of both heterodimeric reaction centre proteins, D1 and D2, remained constant under growth light conditions, indicating that the number of PSII centres in the membranes was not affected, only the form of the D1 protein was changed from D1:1 to D1:2 in most centres. When the cells were photoinhibited either at 500 or 1000 mumol photons m-2 s-1, in the presence or absence of the protein synthesis inhibitor lincomycin, the D1:2 protein remained at a higher level in cells in which over-expression had been induced by IPTG. These cells were also less prone to photoinhibition of PSII. It is suggested that the tolerance of cells to photoinhibition increases when most PSII reaction centres contain the D1:2 protein at the beginning of high irradiance. This tolerance is further strengthened by maintaining psbAIII gene over-expression during the photoinhibitory treatment.

Amino Acid Sequence↗

PubMed1996

Analysis of the cellular origin of hepatocellular carcinoma by p53 genotype.

The polymerase chain reaction and HaeIII enzymatic digestion were used to study the seventh exon of the p53 gene in 29 primary and recurrent hepatomas in paraffin-embedded samples from 11 patients. The mutation rate of the p53 gene and its genotypes in samples of primary and recurrent tumours and multiple nodules were investigated. The cellular origins of hepatocellular carcinoma were analysed by p53 genotype. p53 mutation rates were found to be 69.0% (20/29) in the primary and recurrent tumours, 58.8% (10/17) in tumours with a single nodule and 83.3% (10/12) in tumours with multiple nodules. The p53 genotypes were found to be different in 6 pairs of primary and recurrent tumours, and another 5 pairs had the same p53 genotypes. The samples with multiple nodules in the same patients had the same p53 genotypes. Seven recurrences were of multicentric origin and four were of unicentric origin. It is suggested that the recurrent lesions developed from both unicentric and multicentric origins.

Adult↗

PubMed1996

Modulation of zeta-protein kinase C by cyclic AMP in PC12 cells occurs through phosphorylation by protein kinase A.

Although cyclic AMP (cAMP) has been reported to cross talk with the protein kinase C (PKC) system, effects of elevated intracellular cAMP on the activities of specific PKC isoforms have not been studied. We report findings from a permeabilized cell assay that was used to examine changes in the activity of the atypical PKC isoforms brought about by exposure of PC12 cells to agents that elevate intracellular cAMP. We found that increases in intracellular cAMP led to rapid stimulation of atypical PKC activity, 40-70% above control, for a sustained period of time, a response that occurred independent of the phorbol 12-myristate 13-acetate (PMA)-sensitive PKC isoforms. Changes in intracellular cAMP levels resulted in a dose-dependent redistribution of zeta-PKC to the cytoplasm with a concomitant increase in the phosphorylation state of the enzyme. Incubation of purified zeta-PKC with increasing concentrations of PKA likewise caused a twofold increase in the phosphorylation state of zeta-PKC. In contrast to the positive effect that PKA-mediated phosphorylation had on the activity of zeta-PKC, the enzyme displayed reduced binding to ras when phosphorylated. Taken together, these findings are consistent with the hypothesis that protein phosphorylation of PKC acts as a positive effector of its enzyme activity and may serve as a negative modulator for interaction with other proteins.

Animals↗

PubMed1996

An 18-base-pair sequence in the mouse proalpha1(II) collagen gene is sufficient for expression in cartilage and binds nuclear proteins that are selectively expressed in chondrocytes.

The molecular mechanisms by which mesenchymal cells differentiate into chondrocytes are still poorly understood. We have used the gene for a chondrocyte marker, the proalpha1(II) collagen gene (Col2a1), as a model to delineate a minimal sequence needed for chondrocyte expression and identify chondrocyte-specific proteins binding to this sequence. We previously localized a cartilage-specific enhancer to 156 bp of the mouse Col2a1 intron 1. We show here that four copies of a 48-bp subsegment strongly increased promoter activity in transiently transfected rat chondrosarcoma (RCS) cells and mouse primary chondrocytes but not in 10T1/2 fibroblasts. They also directed cartilage specificity in transgenic mouse embryos. These 48 bp include two 11-bp inverted repeats with only one mismatch. Tandem copies of an 18-bp element containing the 3' repeat strongly enhanced promoter activity in RCS cells and chondrocytes but not in fibroblasts. Transgenic mice harboring 12 copies of this 18-mer expressed luciferase in ribs and vertebrae and in isolated chondrocytes but not in noncartilaginous tissues except skin and brain. In gel retardation assays, an RCS cell-specific protein and another closely related protein expressed only in RCS cells and primary chondrocytes bound to a 10-bp sequence within the 18-mer. Mutations in these 10 bp abolished activity of the multimerized 18-bp enhancer, and deletion of these 10 bp abolished enhancer activity of 465- and 231-bp intron 1 segments. This sequence contains a low-affinity binding site for POU domain proteins, and competition experiments with a high-affinity POU domain binding site strongly suggested that the chondrocyte proteins belong to this family. Together, our results indicate that an 18-bp sequence in Col2a1 intron 1 controls chondrocyte expression and suggest that RCS cells and chondrocytes contain specific POU domain proteins involved in enhancer activity.

Animals↗

PubMed1996

Association of HLA class II alleles in patients with juvenile myoclonic epilepsy compared with patients with other forms of adolescent-onset generalized epilepsy.

Reports have suggested an association of juvenile myoclonic epilepsy (JME) with an HLA-DR allele. We examined the HLA-DR and DQ frequencies in two populations of epilepsy patients: (1) JME patients and (2) patients with other forms of adolescent-onset, idiopathic generalized epilepsy (IGE). We did DNA-based HLA typing on 24 JME patients and 24 patients with non-JME forms of adolescent-onset IGE, forms that are clinically similar to JME. In typing the HLA region, we paid particular attention to the alleles contributing to the HLA-DR13 type and also to the DQB1 locus alleles that are in linkage disequilibrium with the alleles that comprise the DR13 type. We also examined the HLA-AP locus, which is centromeric to the DR locus. The frequency of DR13 was significantly higher in JME compared with the non-JME patients. Nine JME patients, compared with two non-JME patients, carried that type (chi 2 = 5.78 [p < 0.017, 1 df]). The odds ratio was 6.6. Furthermore, the DQB1 alleles in linkage disequilibrium with the alleles contributing to the DR13 type were also more frequent in JME than in non-JME epilepsy patients. The chi 2 is highly significant (8.1, p < 0.005) with an odds ratio of 13.8. These results confirm that JME is an HLA-associated form of epilepsy. They also show that the JME locus probably lies within the HLA region, most likely between the HLA-DP and HLA-B loci. The association studies also confirm linkage results showing that JME is genetically different from some other IGEs and emphasize that careful diagnosis is critical to genetic studies of the epilepsies.

Adolescent↗

PubMed1996

Molecular weights and isoelectric points of sperm antigens relevant to autoimmune infertility in men.

PURPOSE: We determined the molecular weights and isoelectric points of antigens in the uncapacitated and capacitated spermatozoa of fertile men binding to the serum immunoglobulin G (IgG) from 8 autoimmune infertile men and 8 fertile nonautoimmune men. MATERIALS AND METHODS: We used double fluorochrome cytotoxicity and immunobead binding assays to determine the sperm antibody status of the study subjects. 2-Dimensional gel electrophoresis and Western blot analysis were used to determine the molecular weights and isoelectric points of sperm antigens binding to serum IgG from these men. Amino acid sequencing of the digested peptides of chosen proteins was accomplished. Immune reactivity to the proteins in autoimmune infertile men was further verified. RESULTS: Serum IgG from fertile men failed to react significantly. Serum IgG from all autoimmune men (100%) showed significant binding to proteins with a molecular weight of 92 kDa. and isoelectric points of 3.5 to 4.0 in the capacitated spermatozoa. Six of 8 infertile men (75%) had serum IgG binding to capacitated sperm antigens with a molecular weight of 18 kDa. and isoelectric points of 4.5 to 5.2. Amino acid sequencing of peptides of the 92 kDa. protein matched complement component 1 (C1) inhibitor, with noted differences in the amino acid sequencing from the latter. The 18 kDa. protein matched calmodulin. We verified that serum IgG from autoimmune infertile men bound with C1 inhibitor and ascertained that the 92 kDa. protein in the spermatozoa was C1 inhibitor-like protein. CONCLUSIONS: Significant antibody responses to C1 inhibitor-like protein and calmodulin were noted in autoimmune men. Both of these proteins may be of testicular origin and these autoimmune responses may be highly relevant to infertility.

Amino Acid Sequence↗

PubMed1996

A novel cis-acting element is involved in the promoter activity of the rat mdr1b gene.

Multidrug resistance (MDR) is often associated with overexpression of P-glycoprotein, which is encoded by the mdr gene family. Three mdr genes, i.e., mdr1a (mdr3), mdr1b (mdr1), and mdr2 are present in rodents, and the expression of these genes is temporally and tissue specifically regulated. Furthermore, expression of mdr1b is highly elevated during rat hepatocarcinogenesis. To elucidate how mdr1b expression is regulated, we cloned the genomic sequence of the rat mdr1b gene and functionally dissected its 5' promoter region in various cell lines. The transcription start site identified by the primer extension and RNase protection assays is identical to that of the murine mdr1b homologue. Sequence analysis revealed that the proximal region (within -1300 bp) of the rat mdr1b gene also shares striking similarity to that of the mouse mdr1b gene. Transient transfection assays using reporter gene constructs containing various lengths of the 5' mdr1b sequences revealed that the sequence located between-247 to -126 bp was important for the expression of the reporter gene in many different cell lines. Further analyses revealed that at least one regulatory element located at -189 to -167 bp, which contained the palindromic sequence 5'-AGACATGTCT-3' (-189 to -180 bp), is involved in the promoter function. Gel mobility shift assays demonstrated that this palindromic sequence is essential for specific protein binding. UV cross-linking experiments identified that two major proteins with molecular masses of approximately 41 and 49 kDa were associated with this sequence. A Genbank search and gel motility shift assay competition experiment suggested that the specific binding protein(s) appears to be a novel transcription factor involved in the regulation of the rat mdr1b gene expression.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1996

[A study of the variation of the (AT)xTy motif-530bp 5' to the beta-globin gene in the Chinese population].

The repeated purine-pyrimidine motif (AT)xTy at the region -530bp 5' to the beta-globin gene is regarded as the binding site for BP1, a transcriptionally repressive nuclear protein. In present study, the rearrangement patterns of the -530 motif in the Chinese population, including 43 patients with various hemoglobinopathies and part of their relatives (34), as well as 20 hematologically normal individuals, were investigated with the method of ds-DNA cycle sequencing. The results showed that the -530 motif in Chinese people had three major variation types-(AT)8T5, (AT)7T7 and (AT)9T5. Besides, a novel rearrangement type, (AT)10T3, was found in a hematologically normal family. Furthermore, the analysis of haplotype between the beta-globin structural loci and the -530 motif rearrangement indicated that linkage disequilibrium existed between three mutant beta-globin genes (i.e., IVS-II-654(C-->T), CD41-42(-4bp) and HbE), and three -530 motif rearrangement types (i.e., (AT)8T5, (AT)7T7 and (AT)9T5)7 respectively.

Asian People↗

PubMed1996

[Analysis of 106,272 cases of postterm pregnancy in China].

106272 cases of postterm pregnancy in 945 hospitals in China during the period from Oct. 1986 to Sept. 1987 were surveyed, the overall incidence rate was 85.48/1000. Provincially, the highest two rates were 127.36/1000 and 120.92/1000 in Jilin and Shandong provinces respectively, and the lowest two rates 53.98/1000 and 61.38/1000 in Xizang and Qinghai provinces respectively. The perinatal mortality was 27.90/1000 (corrected 12.49/1000). The incidence of macrosomia (89.50/1000) in postterm pregnancy was twice as much as that in term delivery. Postterm pregnancy was more frequent in pregnant women of 20-34 years old,and of 42 weeks' gestation. The incidence malformations in postterm pregnancy was 154.13 per ten thousand, in which the frequency of malformations associated with low birth weight was three times that associated with macrosomia.

Adult↗

PubMed1996

[Current situation and analysis on the infection of Salmonella typhimurium in Henan province].

This paper reported present situation of nosocomial infection with S. typhimurium, and the characteristics of food poisoning outbreaks in Henan province in recent years. It is concluded that the main causes of nosocomical infection due to lacking of strict isolation system and disinfective measures together with environmental pollution in hospitals and medical treatment by medical staff. Measures as to control for nosocomial infection, strengthen sterilization and isolation, establish "Baby Friendly Hospital" popularize breast-feeding, increase foundational facilities, improve therapeutic methods etc. will play an active roles. It was suggested that long time S.typhimurium carriers in adults might be potential risk to the community. Along with improvement of living standard of the people, attention must be paid to meat, egg, poultry contamination by S.typhimurium.

Child↗

PubMed1996

[An estimate of recurrence risk for neural tube defects in China].

A retrospective survey was made for estimating the recurrence risk of neural tube defects (NTD) in 233 hospitals of China during the period from July 1990 to June 1993. A total of 2159 women who born a baby with NTD in this pregnancy were investigated. Among them, 674 had one or more previous births (total in 889 births) before this pregnancy. Of the 889 children, 61 had NTD. Thus the overall estimate recurrence risk of NTD is 6.86%. The estimate recurrence risk of NTD is correlated with the prevalence. The estimate recurrence risks are 3.70%, 4.50% and 8.32% in the low-, average and high-prevalence areas respectively. There is a high recurrence risk for the same defect (anencephaly of spina bifida or encephalocele) of the index case.

Anencephaly↗

PubMed1995

Determination of polyamines in serum by high-performance capillary zone electrophoresis with indirect ultraviolet detection.

A method for determining polyamines in serum by capillary zone electrophoresis (CZE) with indirect ultraviolet detection was established. The concentrations of polyamines in the sera of six healthy adults were determined and the results were in accordance with those obtained previously by high-performance liquid chromatography (HPLC). However, the CZE method is superior to HPLC in that it has high sensitivity, small sample consumption and easy sample pretreatment.

Adult↗

PubMed1995

Use of a new rat chondrosarcoma cell line to delineate a 119-base pair chondrocyte-specific enhancer element and to define active promoter segments in the mouse pro-alpha 1(II) collagen gene.

We show that a new rat chondrosarcoma (RCS) cell line established in long-term culture from the Swarm tumor displayed a stable differentiated chondrocyte-like phenotype. Indeed, these cells produced the collagen types II, IX, and XI and alcian blue-stainable cartilage-specific proteoglycans, but no type I or type III collagen. To functionally characterize their chondrocytic nature, the cells were stably transfected with a type II collagen/beta geo chimeric gene which confers essentially perfect chondrocyte-specific expression in transgenic mice. RCS cells expressed both beta-galactosidase and G418 resistance, in comparison with similarly transfected 10T1/2 and NIH/3T3 fibroblasts which did not. These cells were then used to perform a systematic deletion analysis of the first intron of the mouse type II collagen gene (Col2a1) using transient expression experiments to determine which segments stimulated expression of a luciferase reporter gene in RCS cells but not in 10T1/2 fibroblasts. Cloning of two tandem copies of a 156-base pair (bp) intron 1 fragment (+2188 to +2343) in a construction containing a 314-bp Col2a1 promoter caused an almost 200-fold increase in promoter activity in RCS cells but no increase in 10T1/2 cells. DNase I footprint analysis over this 156-bp fragment revealed two adjacent protected regions, FP1 and FP2, located in the 3'-half of this segment, but no differences were seen with nuclear extracts of RCS cells and 10T1/2 fibroblasts. Deletion of FP2 to leave a 119-bp segment decreased enhancer activity by severalfold, but RCS cell specificity was maintained. Further deletions indicated that sequences both in the 5' part of the 119-bp fragment and in FP1 were needed simultaneously for RCS cell-specific enhancer activity. A series of deletions in the promoter region of the mouse Col2a1 gene progressively reduced activity when these promoters were tested by themselves in transient expression experiments. However, these promoter deletions were all activated to a similar level in RCS cells by a 231-bp intron 1 fragment that included the 156-bp enhancer. The RCS cell-specific activity persisted even if the Col2a1 promoter was replaced by a minimal adenovirus major late promoter. This 231-bp intron 1 fragment also had strong enhancing activity in transiently transfected mouse primary chondrocytes. Our experiments establish the usefulness of RCS cells as an experimental system for studies of the control of chondrocyte-specific genes, provide an extensive delineation of segments in the Col2a1 first intron involved in chondrocyte-specific activity, and show that promoter sequences are dispensable for chondrocyte specificity.

3T3 Cells↗

PubMed1995

Electron transport regulates exchange of two forms of photosystem II D1 protein in the cyanobacterium Synechococcus.

Synechococcus sp. PCC 7942 modulates photosynthetic function by transiently replacing the constitutive D1 photosystem II protein, D1:1, with an alternate form, D1:2, to help counteract photoinhibition under excess light. We show that a temperature drop from 37 to 25 degrees C also drives D1:1/D1:2 exchange under constant, moderate light. Chilling or light-induced D1 exchange results from rapid loss of psbAI message coding for D1:1 and accumulation of psbAII and psbAIII messages coding for D1:2. During chilling, a large pool of a novel form, D1:2*, transiently accumulates, distinguishable from normal D1 by an increase in apparent molecular mass. D1:2* is not phosphorylated and is probably a functionally inactive, incompletely processed precursor. After acclimation to 25 degrees C, D1:2* disappears and D1:1 again predominates, although substantial D1:2 remains. Partial inhibition of electron transport under constant, moderate light also triggers the D1 exchange process. These treatments all increase excitation pressure on photosystem II relative to electron transport. Therefore, information from photosynthetic electron transport regulates D1 exchange without any requirement for a change in light intensity or quality, possibly via a redox sensing mechanism proximal to photosystem II.

Antioxidants↗

PubMed1995

Role of angiotensin II and prostaglandin E2 in regulating cardiac fibroblast collagen turnover.

In hypertensive heart disease, after myocardial infarction or in congestive heart failure, myocardial fibrosis presenting as a diffuse perivascular and interstitial accumulation of fibrillar collagens within the normal connective tissue structures of the myocardium is associated with an activated renin-angiotensin system (RAS). This reactive fibrosis occurs in the overloaded left ventricle and the nonoverloaded right ventricle irrespective of myocyte necrosis or the development of myocyte hypertrophy. Therefore, it appears that hemodynamic factors or the load of the ventricle are not primarily responsible for the adverse fibrous tissue response in the myocardium, and humoral factors may play a key role in regulating the myocardial collagen matrix. The neurohumoral response in hypertensive heart disease, after myocardial infarction with overall deterioration of left ventricular function or congestive heart failure leads to an activation of either the cardiac or the circulating RAS, which closely interacts with the bradykinin-prostaglandin system. To ascertain whether the RAS modulates collagen fibroblasts that express mRNAs for types I and III collagens (the major fibrillar collagens in the heart) and matrix metalloproteinase 1 (MMP1; the key enzyme for collagen degradation), collagen synthesis was measured by [3H]proline incorporation normalized to total protein synthesis and MMP1 activity was determined by degradation of [14C]collagen in cultured fibroblasts after 24-hour incubation with various concentrations of angiotensin II or PGE2 (10(-11)-10(-3) M) under serum-free conditions. In addition, effects of angiotensin II were evaluated in the presence or absence of either type 1 (ICI D8731) or type 2 (PD 123177) angiotensin II (AT1 or PGE2 (10(-11)-10(-3) M) under serum-free conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Identification and characterization of a hepatoma cell-specific enhancer in the mouse multidrug resistance mdr1b promoter.

The expression of multidrug resistance/P-glycoprotein genes mdr1b(mdr1) and mdr1a(mdr3) is elevated during hepatocarcinogenesis. To investigate the regulation of mdr1b gene expression, we used transient transfection expression assays of reporter constructs containing various 5'-mdr1b flanking sequences in hepatoma and non-hepatoma cells. We found that nucleotides -233 to -116 preferentially enhanced the expression of reporter gene in mouse hepatoma cell lines in an orientation- and promoter context-independent manner. DNase I footprinting using nuclear extracts prepared from hepatoma and non-hepatoma cells identified four protein binding sites at nucleotides -205 to -186 (site A), -181 to -164 (site B), -153 to -135 (site C), and -128 to -120 (site D). Further analyses revealed that, while site B alone played a major part for the enhancer function, sites A and B combined conferred full enhancer activity. Site-directed mutagenesis results also supported these results. Gel retardation experiments using oligonucleotide competitors revealed that the site B contains a dominant binding protein. This is the first report demonstrating a cell type-specific enhancer in the mdr locus. The role of this enhancer in the activation of mdr1b gene during hepatocarcinogenesis is discussed.

ATP Binding Cassette Transporter, Subfamily B, Mem↗