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F Wang

Publications and source records attributed to F Wang.

At least 559 records · Page 31Linked to original sources
PubMed1995

Neurotransmitter receptors in the developing cerebral cortex.

This review deals with several aspects of neurotransmitter receptor development in the primate cerebral cortex. It describes the presence of multiple neurotransmitter receptors in the transient zones of the fetal cerebral wall. These zones are involved in the production and migration of cortical neurons and the establishment of appropriate innervation of the cortex. It also suggests functions that neurotransmitter receptors may perform in these embryonic zones. In addition, this review shows that a remarkable diversity of neurotransmitter receptors develops concurrently in disparate areas of the primate cerebral cortex and discusses the implications of this finding on our understanding of the general principles underlying development of the cerebral cortical circuitry. Finally, it speculates on factors that may be involved in regulation of neurotransmitter receptor development in the primate cerebral cortex.

Animals↗
PubMed1994

Electrophoresis of proteins and protein-protein complexes in native polyacrylamide gels using a horizontal gel apparatus.

Electrophoresis of proteins and protein-protein complexes in polyacrylamide gels under native conditions using a horizontal gel apparatus is described. The advantage of this system is that it permits the detection of both negatively and positively charged proteins as well as protein-protein complexes in the same gel. During electrophoresis, a continuous gel sandwiched between two glass plates is placed horizontally on the platform and submerged in a reservoir buffer. The sample wells are made along the center of the gel, allowing positively and negatively charged proteins to migrate toward the cathode and anode, respectively. Several proteins with varying molecular weights and isoelectric point (pI) values and pairs of proteins capable of forming protein-protein complexes were chosen as model systems to illustrate the methodology. The effects of several parameters on the performance of the gel system including protein molecular weight, pI, and gel concentration were also examined and the results obtained by this method are comparable to those obtained by the vertical system. Following electrophoresis, both negatively and positively charged proteins as well as protein-protein complexes can be transferred by electroblotting onto polyvinylidene difluoride membranes for further analyses.

Electrophoresis, Polyacrylamide Gel↗
PubMed1994

Undetected eye disease in a primary care clinic population.

BACKGROUND: Population-based data have indicated that a significant proportion of persons with undiagnosed ocular disease in the community are regular users of general medical services. This, combined with the high prevalence of chronic medical disorders known to be risk factors for ocular disease in such clinics, makes them an attractive site for screening. METHODS: The prevalence of ocular disease was estimated in a sample of 405 general medicine patients attending an adult primary care clinic in an urban teaching hospital. RESULTS: Overall, 205 (50.6%) of 405 patients were found to have clinically important ocular pathology. One third of those affected (n = 68) were unaware of their eye disease, and 26% (n = 18) of these 68 patients required immediate medical or surgical intervention. Patients 65 years or older (odds ratio [OR], 1.76), in fair or poor general health (OR, 1.78), with diabetes mellitus (OR, 2.07), or with self-reported fair or poor vision (OR, 3.03), were at increased risk for the presence of ocular disease. Among patients with eye disease, those who had no insurance coverage for eye care (OR, 3.45), those who had not had an eye examination during the previous 2 years (OR, 4.03), and those whose last eye examination was performed by an optometrist (OR, 7.25, reference ophthalmologist) were more likely to not be aware of their eye disease. CONCLUSIONS: Our results underscore the importance of screening for ocular disease in primary health care settings, especially for patients who are older than 65 years, are in poor health, report poor vision, have had infrequent eye examinations, or have inadequate insurance coverage for eye care.

Adult↗
PubMed1994

Genomic structure and cloned cDNAs predict that four variants in the kinase domain of serine/threonine kinase receptors arise by alternative splicing and poly(A) addition.

Heterodimers of types I and II serine/threonine kinase receptor monomers compose the active receptor complex for ligands of the transforming growth factor beta family. Here we show that the genomic organization of coding sequences for the intracellular domain of a widely expressed type I serine/threonine kinase receptor is similar to that of the activin type II receptor gene. The genomic structure and cDNA clones indicate that poly(A) addition to alternative exons at each of three carboxyl-terminal coding exon-intron junctions may be a common feature of both type I and II receptor genes. The predicted products are monomers truncated at kinase subdomains VII, IX, and X which vary in kinase activity and potential serine, threonine, and tyrosine phosphorylation sites. These results suggest that combinations of variants that affect the signal-transducing intracellular kinase domain of both type I and II receptor monomers within the transforming growth factor beta ligand family may add to the heterogeneity of biological effects of individual ligands in the family.

Alternative Splicing↗
PubMed1994

Characterization of an acetylcholine receptor alpha 3 gene promoter and its activation by the POU domain factor SCIP/Tst-1.

Genes encoding neuronal nicotinic acetylcholine receptors exhibit restricted patterns of expression in the nervous system. We are interested in elucidating the molecular mechanisms responsible for establishing these patterns of expression. This paper presents the characterization of regulatory elements upstream of the neuronal nicotinic acetylcholine receptor alpha 3 gene. We have identified a GC-rich multistart site promoter adjacent to the alpha 3 coding region. Similar alpha 3 start sites were identified in PC12 cells and sympathetic ganglion neurons, suggesting similar control mechanisms in the clonal line and peripheral neurons. The start site region lacks TATA-like sequences but does contain initiator-like sequences. We show, in transient transfection assays, that the POU domain transcription factor, SCIP/Tst-1, specifically activates alpha 3 in a neural context. Other POU domain factors tested only weakly activated or repressed alpha 3. Unexpectedly, we found that alpha 3 basal activity and SCIP/Tst-1 activation of alpha 3 is not dependent on the SCIP/Tst-1 binding sites found upstream of the gene. In addition, mutations in the SCIP/Tst-1 coding region that prevent the factor from binding to DNA with high affinity do not obliterate alpha 3 activation. These results lead us to propose that alpha 3 activation by SCIP/Tst-1 is achieved via protein-protein interactions between SCIP/Tst-1 and a specific complement of transcription factors that act directly on the promoter.

Animals↗
PubMed1994

Effects of selenium and alpha-tocopherol on liver damage induced by feeding grains from an endemic area of Keshan disease in rats.

Previous studies have shown the pathogenic effects of grains cultivated in the endemic areas of Keshan disease and selenium is effective in the prevention of this disease. In this study, liver damages induced by feeding grains from an endemic area (endemic diet), and the effects of selenium and alpha-tocopherol supplement were examined. After 3 months on the endemic diet, the amounts of serum enzymes were significantly increased when compared to controls (animals receiving diet from a non-endemic area). Liver enzymes (alkaline phosphatase and choline esterase) were also found to be altered in the serum, further suggesting liver damages in animals on an endemic diet. Supplement of the endemic diet with selenium or alpha-tocopherol reversed the changes in serum enzymes. Increase in lipid peroxidation in the liver of animals on the endemic diet was observed when compared to that in control animals. Selenium and alpha-tocopherol supplements prevented the increase in lipid peroxidation in the liver by the endemic diet. Semi-quantitative histochemical analysis of glutamate dehydrogenase and succinate dehydrogenase in liver tissue showed that the livers of animals on an endemic diet were more sensitive to ischemic damages in vitro. Supplementation of the endemic diet with either selenium or alpha-tocopherol reduced the sensitivity to ischemic damages. The results suggest that increased lipid peroxidation in the liver of rats on an endemic diet may be responsible for liver damages and elevation of serum enzymes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Screening for glaucoma in a medical clinic with photographs of the nerve fiber layer.

PURPOSE: To evaluate nerve fiber layer photography as a method for glaucoma screening in a general medical clinic setting. METHODS: One hundred seventy-one persons who attended an academic hospital medical clinic were administered a questionnaire and underwent a complete eye examination, including automated perimetry and photography of the optic disc and nerve fiber layer. RESULTS: Eighteen patients were diagnosed as having primary glaucoma; one, secondary glaucoma; and 21 were suspected of having glaucoma. Nerve fiber layer photographs were taken on 145 persons (85%) and were readable in 136 (80%) of the sample of 171 subjects. Nerve fiber layer atrophy was detected on masked evaluation in 64% of those with glaucoma, in 28% of those suspected of having glaucoma, and in 16% of persons who did not meet the criteria for glaucoma. CONCLUSIONS: Nerve fiber layer photography can be carried out as a screening method and can identify a substantial proportion of those with glaucoma. It compares favorably with tonometry, cup-disc ratio estimation, or screening visual field examination for glaucoma detection.

Adult↗
PubMed1994

Epstein-Barr virus (EBV) latent membrane protein 1 increases HLA class II expression in an EBV-negative B cell line.

Transformation of normal resting B cells by the Epstein-Barr virus (EBV) leads to the establishment of permanent lymphoblastoid cell lines (LCL) which express high levels of HLA antigens and which are highly efficient in antigen presentation. Certain features of the LCL phenotype can be reproduced by transfecting EBV-negative B lymphoma (BL) cell lines with individual EBV latent genes under heterologous promoters. In this work we have analyzed a series of subclones derived from the EBV-negative cell line Louckes, stably transfected with constructs encoding EBV latent genes for their expression of HLA class II molecules. Louckes parental cells and control transfectants expressed detectable levels of HLA-DR, DQ and DP antigens on the cellular surface by cytofluorometry, but these levels were significantly increased in transfectants expressing the virus-coded latent membrane protein 1 (LMP-1). Northern blotting for the individual alpha and beta chain mRNA at each of the three HLA class II loci indicated correspondingly increased levels of HLA class II transcripts in the LMP-1 transfectants. Transfectants expressing the virus-coded nuclear antigens EBNA-1, EBNA-2 or EBNA-LP showed no significant changes in these parameters. These observations indicate that up-regulation of HLA-class II molecules can be a part of the changes induced by LMP-1 in B cells.

Antigens, Viral↗
PubMed1994

Mouse fibroblasts defective in thrombin mitogenesis possess functional proteolytically activated receptor for thrombin: requirement for a second signaling pathway.

Thrombin mitogenesis in fibroblasts requires two distinguishable subsets of signals; one generated by proteolytic cleavage, the other by high-affinity cell surface binding. Characterizing two closely related mouse embryo (ME) cell lines with high numbers of thrombin binding sites, we found that one line, B11-A, responds mitogenically to thrombin, epidermal growth factor (EGF), and serum, whereas the B11-B cell line is responsive to EGF and serum, but not to thrombin. The B11-B defect responsible for loss of thrombin responsiveness is not due to differences in the number of high-affinity binding sites, the affinity of thrombin binding to these sites, or to differences in cell surface expression of proteolytically activated receptors for thrombin (PART). The defect is also not associated with an inability of thrombin to activate PART since thrombin stimulates the cleavage-dependent induction of the proto-oncogene c-fos in both B11-A and B11-B cells. Various combinations of thrombin, synthetic thrombin receptor peptide, TRP-14 (SFFLRNPGENTFEL), platelet-derived growth factor (PDGF), and phorbol 12-myristate 13-acetate (PMA) were used to better define the defect in thrombin-mediated mitogenesis in B11-B cells. Direct activation of protein kinase C with PMA in combination with thrombin did not overcome B11-B nonresponsiveness. However, mitogenic responsiveness was regained in B11-B cells by simultaneous addition of PDGF and either thrombin or TRP-14. Therefore, the B11-B defect may involve a set of signals initiated by nonproteolytic thrombin interactions distinct from those initiated by PART, but related to the downstream signals initiated by the tyrosine kinase-associated growth factors, EGF and PDGF.

Amino Acid Sequence↗
PubMed1994

Molecular cloning and expression of the gene for a major leucine-rich protein from human hepatoblastoma cells (HepG2).

The human hepatoblastoma cell line, HepG2, exhibits an array of stable properties in culture that have made it a popular cell culture model for studies on regulation of liver-specific gene expression and properties of hepatoma cells. In contrast to other hepatoma cell lines, HepG2 cells overexpress a characteristic detergent-extractable, wheat germ lectin-binding protein with apparent molecular mass of 130 kDa. Using an antibody to screen a phage expression library of HepG2 complementary DNA (cDNA), we identified and cloned a 4734 base pair cDNA which codes for a 130-kDa leucine-rich protein (lrp 130) when expressed in transfected cells. The deduced sequence of lrp130 exhibits sequences weakly homologous to the consensus sequence for the ATP binding site in ATP-dependent kinases and the protein kinase C phosphorylation site of the epidermal growth factor receptor. Consistent with the higher levels of expression of lrp130 antigen, Northern hybridization analysis indicated that HepG2 cells express high levels of the major 4.8 kilobase lrp130 mRNA relative to other hepatoma cells. Although currently of unknown function, lrp130 may be of utility as a marker for liver cell lineages represented by the HepG2 cell line.

Amino Acid Sequence↗
PubMed1994

A prospective evaluation of antituberculosis therapy in patients with human immunodeficiency virus infection.

The purpose of this study was to determine the efficacy and toxicity of a standard antituberculosis regimen in patients with human immunodeficiency virus (HIV) infection. We prospectively evaluated 89 patients with tuberculosis and HIV infection at an urban medical center. Eighty-two patients received isoniazid, rifampin, and pyrazinamide, with or without ethambutol, for 2 mo, followed by isoniazid and rifampin for 7 mo. Seven patients received other regimens because of drug resistance or intolerance. Therapy was self-administered in 57 patients and directly observed in 32 cases. All patients showed rapid clinical improvement during the first month of therapy, and sputum cultures reverted to negative after 3 mo in 52 of 54 patients from whom specimens were obtained. Adverse reactions to isoniazid or rifampin prompted alterations in antituberculosis regimens in five patients (6%). Forty patients (45%) died during follow-up, and tuberculosis was a potential contributory cause of death in three cases. Treatment failure occurred in five patients (6%), four of whom were noncompliant with therapy. The fifty patient had an isoniazid-resistant organism. No relapses occurred in 916 patient-months of follow-up posttreatment. We thus conclude that the 9-mo regimen used for treatment of drug-susceptible tuberculosis in HIV-infected patients is effective and well tolerated.

AIDS-Related Opportunistic Infections↗
PubMed1994

[Posturography classification and clinical application].

W-I computerized posturography system, designed by authors of this article, was introduced. Using this system body sway was measured in 60 normal adults and 484 patients with vertigo. 204 patients with confirmed clinical diagnoses were analyzed. Posturography (PSG) may be classified in 16 composite graphic types. Statistics suggested that PSG of 84.5% patients with unilateral peripheral vestibular dysfunction show that the left-right direction graphic type and of 77.8% patients with front-back direction graphic type. The mechanism of the above-mentioned types of posturography was discussed.

Adult↗
PubMed1994

Depression of cytotoxicity of nonparenchymal cells in the liver after surgery.

BACKGROUND: The nonparenchymal cells (NPCs) of the liver have a strong cytotoxic activity. Our hypothesis is that their activity, which prevents metastases to the liver, may be impaired after operation. METHODS: First, Sprague-Dawley rats underwent either a sham operation consisting of only a laparotomy (group L, n = 10), a laparotomy and resection of a portion of the small intestine (group R, n = 10) or no operation (group C, n = 10). After 2 days liver NPCs were isolated and divided into two fractions, large and small NPCs. The cytotoxicity of the liver NPCs and of the circulating blood mononuclear cells (BMC) was assessed. Second, we measured the growth of tumor metastases 14 days after the inoculation of a cell line (MRMT-1) into the portal vein of rats undergoing similar surgical stress (group Rm, n = 10 and group Lm, n = 10). RESULTS: The natural killer cell activity (anti-YAC-1) of large NPCs was 38% in group R, which was significantly less (p < 0.002) than that in groups L (72%) and C (83%). Small NPCs showed reduced natural killer activity in groups R and L (26% and 35%, respectively) compared with that in group C (70%) (p < 0.02). The natural killer cell activity of BMCs was similar in each group, and the lymphokine-activated killer cell activity (by anti-EL4) did not change in either the NPCs or BMCs. In the second experiment the area of the tumors occupied in the liver in the group Rm rats was significantly greater compared with that in the group Lm rats (p < 0.01). CONCLUSIONS: Surgical stress depressed the cytotoxic activity of liver NPCs and enhanced the growth of metastatic liver tumors. This suggests the possibility that perioperative immunotherapy might be clinically useful in the future to prevent liver metastases after gastrointestinal surgery.

Animals↗
PubMed1994

[The relationship between the major components of extracellular matrix and growth, motility and invasion in mice pulmonary adenocarcinoma].

After mouse pulmonary adenocarcinoma cell line LA795 was implanted in the subrenal capsule of T739 mice, the local distribution of fibronectin (FN), laminin (LN) and type IV collagen was detected by indirect immunoperoxidase and immunofluorescence staining and were observed during tumor growth at different time intervals. As the tumors progressed, it was shown that the expression of FN decreased while that of LN and type IV collagen gradually increased, their distribution patterns were also different. LN and type IV collagen were absent in the basement membrane in the tumor invasion areas. In order to verify the in vivo observations, various in vitro methods were used. We found expression of FN and LN but no expression of type IV collagen mRNA in LA795 cell line. Assay of random migration of tumor cells was employed to check the influence of FN, LN or type IV collagen on the motility of tumor cells. It was demonstrated that LN, FN, type IV collagen and in particular, LN could promote the motility of tumor cells individually. Cultured with addition of LN or FN, tumor cell colonies expanded diametrically more rapidly. The results indicated that FN, LN and type IV collagen may contribute to tumor invasion and metastasis.

Adenocarcinoma↗
PubMed1993

A novel cell culture technique for electron microscopy.

A simplified technique for the monolayer growth of cultured cells and their in situ embedment on the inner surface of the pyramidal portion of the Beem capsule for electron microscopy has been developed. The results demonstrated that the cell monolayers grew well on the surface of the Beem capsule and could be embedded in situ. Electron micrographs showed cells in their natural state of contact with one another. The plasma membrane and intracellular organelles were well preserved. This method minimizes many difficult steps and eliminates the disruption of cells by scraping, pelleting, or enzymatic reaction to remove them.

Humans↗