PubMed Health⌕ Search

Biomedical subjects

F S Wang

Publications and source records attributed to F S Wang.

At least 19 recordsLinked to original sources
PubMed1996

Function of myosin-V in filopodial extension of neuronal growth cones.

The molecular mechanisms underlying directed motility of growth cones have not been determined. The role of myosin-V, an unconventional myosin, in growth cone dynamics was examined by chromophore-assisted laser inactivation (CALI). CALI of purified chick brain myosin-V absorbed onto nitrocellulose-coated cover slips inhibited the ability of myosin-V to translocate actin filaments. CALI of myosin-V in growth cones of chick dorsal root ganglion neurons resulted in rapid filopodial retraction. The rate of filopodial extension was significantly decreased, whereas the rate of filopodial retraction was not affected, which suggests a specific role for myosin-V in filopodial extension.

Adenosine Triphosphate↗
PubMed1996

Spectrin-actin interaction is required for neurite extension in NB 2a/dl neuroblastoma cells.

Spectrin is an actin-binding membrane skeleton protein involved in the maintenance of cell shape and generation of distinct membrane protein domains. Actin binds to the N-terminal domain of beta-spectrin. To examine the function of spectrin-actin interaction in neurons, we sought to disrupt this interaction in differentiating NB 2a neuroblastoma cells by microinjecting an N-terminal domain-specific anti-beta-spectrin antibody. We found that microinjection of the affinity-purified N-terminal domain-specific anti-beta-spectrin inhibited the extension of the neurites in NB 2a/dl cells. The microinjected cells remained flat, and put out many filopodia-like processes; but these processes failed to extend when the cells were induced to differentiate in the presence of dbc AMP or in serum-free medium. The N-terminal domain-specific anti-beta-spectrin also inhibited the binding of spectrin to actin. By contrast, the microinjection of monospecific anti-alpha-spectrin(G) did not inhibit neurite extension. These results suggest that beta-spectrin-actin interaction may be required for neurite extension, which is critical for development of polarity in nerve cells.

Actins↗
PubMed1996

Neutrophil elastase inhibitor (ONO-5046) decreases cytokine-induced neutrophil chemoattractant after reperfusion of pancreaticoduodenal transplantation in rats.

The protective effects of a neutrophil elastase inhibitor (ONO-5046) on reperfusion injury following pancreaticoduodenal transplantation in rats were studied by measuring serum concentrations of cytokine-induced neutrophil chemoattractant (CINC). Male Wistar rats were transplanted with syngeneic pancreaticoduodenal grafts. ONO-5046 was injected intravenously 5 min before vascular clamping and immediately after reperfusion at a dose of 10 mg/kg. No significant differences were observed in the peak serum concentrations of amylase between the groups treated with and treated without ONO-5046. The serum lipase concentrations in the untreated animals increased and peaked 3 hr after reperfusion. ONO-5046 significantly decreased the peak serum lipase concentration. The serum CINC concentrations, which were determined by enzyme-linked immunosorbent assay, increased and peaked 3 hr after reperfusion, decreasing gradually thereafter. However, pretreatment with ONO-5046 significantly inhibited the rise in serum CINC concentrations after reperfusion. Expression of CICN transcripts in the pancrease grafts was evaluated by Northern blot analysis and peaked 3 hr after reperfusion in untreated animals. Pretreatment with ONO-5046 also significantly inhibited the expression of CINC mRNA transcripts in the graft. ONO-5046 significantly decreased the number of neutrophils accumulated in the pancreas graft 24 hr after transplantation. In vitro CINC production by peritoneal macrophages was increased by neutrophil elastase in dose-dependent fashion. However, ONO-5046 decreased CINC production by peritoneal macrophages in response to neutrophil elastase. These results suggest that ONO-5046 prevents early neutrophil accumulation in the pancreas following ischemia/reperfusion of pancreaticoduodenal transplantation.

Animals↗
PubMed1996

Talin and vinculin play distinct roles in filopodial motility in the neuronal growth cone.

Filopodial motility is critical for many biological processes, particularly for axon guidance. This motility is based on altering the F-actin-based cytoskeleton, but the mechanisms of how this occurs and the actin-associated proteins that function in this process remain unclear. We investigated two of these proteins found in filopodia, talin and vinculin, by inactivating them in subregions of chick dorsal root ganglia neuronal growth cones and by observing subsequent behavior by video-enhanced microscopy and quantitative morphometry. Microscale chromophore-assisted laser inactivation of talin resulted in the temporary cessation of filopodial extension and retraction. Inactivation of vinculin caused an increased incidence of filopodial bending and buckling within the laser spot but had no effect on extension or retraction. These findings show that talin acts in filopodial motility and may couple both extension and retraction to actin dynamics. They also suggest that vinculin is not required for filopodial extension and retraction but plays a role in the structural integrity of filopodia.

Animals↗
PubMed1996

Seroepidemiological survey of lymphocytic choriomeningitis virus in wild house mice in China with particular reference to their subspecies.

Serum samples from 337 wild house mice (Mus musculus) from 35 sites in China, collected in 1992 and 1993, were examined for antibodies against lymphocytic choriomeningitis virus (LCMV). Ten samples from eight sites were found to contain such antibodies. Six of the eight positive sites were located in the territory of M. m. gansuensis. One of the other two sites was located in the territory of M. m. castaneus in southern China and the other site was in a habitat of M. m. castaneus which had invaded into the western end of the territory of M. m. homourus. It seems likely that LCMV is distributed in the territories of M. m. gansuensis and M. m. castaneus in China. This is the first report of detection of these antibodies in wild house mice in China and specifically in the territories of M. m. gansuensis and M. m. castaneus.

Animals↗
PubMed1996

Molecular genetic relationships of the salmonellae.

A multilocus enzyme electrophoresis analysis of 96 strains of the salmonellae distinguished 80 electrophoretic types (ETs) and placed them in eight groups, seven of which correspond precisely to the seven taxonomic groups (I, II, IIIa, IIIb, IV, V, and VI) previously defined on the basis of biotype and genomic DNA hybridization. In addition, multilocus enzyme electrophoresis identified an eighth distinctive group (designated VII) composed of five strains that had been assigned to group IV on the basis of biotype. An analysis of variation in the combined nucleotide sequences of five housekeeping genes among 16 strains representing all eight groups yielded estimates of overall genetic relationships that are fully consistent with those indicated by DNA hybridization. However, the nucleotide sequences of seven invasion genes (inv/spa) in the strains of group VII were closely similar to those of strains of group IV. These findings are interpreted as evidence that group VII represents an old, differentiated lineage to which one or more large parts of the chromosomal genome of the group IV lineage, including the 40-kb segment on which the invasion genes are located, have been horizontally transferred. All lines of molecular genetic evidence indicate that group V is very strongly differentiated from all other groups, thus supporting its current taxonomic treatment as a species, Salmonella bongori, separate from S. enterica. The Salmonella Reference Collection C, composed of the 16 strains used in DNA sequence studies, has been established for research on variation in natural populations.

Alleles↗
PubMed1995

The instrumented walker: usage patterns and forces.

Studies documenting the forces that are transmitted through a walker's frame are still scant. The purpose of this study was to evaluate the pattern and magnitude of forces that are transmitted through the frame of a walker during ambulation. A standard aluminum walker was instrumented. Gauges, which were mounted on all four legs, recorded axial, frontal, and sagittally oriented forces. A custom made computerized system registered the forces during 30 seconds of data acquisition. Twelve patients with ambulation dysfunction were tested with this system. Two different usage patterns emerged from the study. One usage pattern was observed in patients who were using the walker as a mean to reduce the amount of weight transmitted through the lower extremity. The second pattern was observed in patients with severe balance problems. These patients used the walker to enhance their balance and stability. The system described allows walker usage pattern analysis. Better understanding of force distribution and usage patterns may lead to improved or new walker design.

Adult↗
PubMed1995

Species limits in Rhizobium populations that nodulate the common bean (Phaseolus vulgaris).

Evolutionary genetic relationships among 146 bean-nodulating Rhizobium strains, including 94 field isolates from three localities in Colombia and 36 strains from Mexico, were examined by multilocus enzyme electrophoresis and restriction fragment length polymorphism analysis of a PCR-amplified 260-bp segment of the 16S rRNA gene. Seventy-five electrophoretic types (ETs), corresponding to multilocus enzyme genotypes, were identified, including a genotypically diverse group of 18 ETs in Colombia that is strongly differentiated from the ETs of R. etli, which occur in Mexico, Colombia, and Brazil. Most strains of the distinctive Colombian ETs carried the same 16S rRNA allele as did strains of R. etli, but, surprisingly, 17 isolates of two of these ETs had the allele that is characteristic of R. leguminosarum, and strains of two other divergent groups of ETs were also polymorphic for the two alleles. No fully satisfactory explanation for the occurrence of the R. leguminosarum 16S rRNA allele in three distantly related groups of strains is available, but horizontal transfer and recombination of the gene, in whole or in part, would seem to be more plausible than convergence in nucleotide sequence.

Alleles↗
PubMed1995

Characterization of Streptococcus agalactiae strains by multilocus enzyme genotype and serotype: identification of multiple virulent clone families that cause invasive neonatal disease.

The chromosomal genotypes of 277 isolates of 16 serotypes of Streptococcus agalactiae were characterized by analysis of electrophoretically demonstrable allele profiles at 12 metabolic enzyme loci. The collection comprised the type strain and 276 strains recovered from French symptomatic and asymptomatic subjects. Sixty-one distinctive electrophoretic types (ETs), representing multilocus clonal genotypes, were identified. Cluster analysis of the ETs revealed two primary phylogenetic divisions separated by a genetic distance of 0.62, Division I contained 67 isolates which could be assigned to 13 ETs. Twenty-seven of these isolates were from samples of cerebrospinal fluid (CSF) from neonatal meningitis patients. Two ETs, separated by a genetic distance of 0.217, contained 26 of these 27 isolates. Division II contained 210 isolates, of which 27 were isolated from CSF. This division was more polymorphic and included 48 ETs. Spanning a genetic distance of 0.3, three clusters and one ET were identified within this group. Twenty-four of 27 strains isolated from CSF belonged to one cluster, and 19 of them belonged to two adjacent ETs with a genetic distance of 0.083. Fifty-five of the 68 serotype Ia strains and 24 of the 26 serotype Ib strains were each confined to one of the evolutionary lineages, and 85 of the 86 strains which carried protein antigen c belonged to phylogenetic division II. Most of the type III organisms were assigned to two clone families. The characteristics of this French population argue for the existence of particular groups of strains responsible for neonatal meningitis and demonstrate that serotyping can supply information about the genetic distribution of strains.

Alleles↗
PubMed1994

Molecular genetic basis of allelic polymorphism in malate dehydrogenase (mdh) in natural populations of Escherichia coli and Salmonella enterica.

Nucleotide sequences of the mdh gene encoding the metabolic enzyme malate dehydrogenase (MDH) were determined for 44 strains representing the major lineages of Escherichia coli and the eight subspecies of Salmonella enterica. Sequence diversity was four times greater in S. enterica than in E. coli, and in both species the rate of amino acid substitution was lower in the NAD(+)-binding domain than in the catalytic domain. Divergence of the mdh genes of the two species apparently has not involved excess nonsynonymous substitutions resulting from the fixation of adaptive amino acid mutations. Allozyme analysis detected 57% of the distinctive amino acid sequences. Statistical tests of the distribution of polymorphic synonymous nucleotide sites identified four possible intragenic recombination events, one involving a single allele of E. coli and three involving alleles of the three subspecies of S. enterica. But recombination at mdh has not occurred with sufficient frequency to obscure the phylogenetic relationships among strains indicated by multilocus enzyme electrophoresis, total DNA hybridization, and sequence analysis of the gapA and putP genes. These findings provide further evidence that the effective (realized) rates of horizontal transfer and recombination for metabolic enzyme and other housekeeping genes are generally low in these species, in contrast to those for loci encoding or mediating the structure of cell-surface and other macromolecules for which recombinants may be subject to strong balancing, directional, or diversifying selection.

Adaptation, Physiological↗
PubMed1994

Distribution of the molossinus allele of Sry, the testis-determining gene, in wild mice.

When the Y chromosome of the laboratory inbred mouse strain C57BL/6 (B6) is replaced by the Y of certain strains of Mus musculus domesticus, testis determination fails and all XY fetuses develop either as hermaphrodites or XY females (XY sex reversal). This suggests the presence of at least two alleles of Sry, the male-determining gene on the Y:M. m. domesticus and B6. The B6 Y chromosome is derived from the Japanese house mouse, M. m. molossinus and therefore carries a molossinus Sry allele. As a first step to determine how the molossinus Sry allele evolved, its distribution pattern was determined in wild mice. The cumulative data of 96 M. musculus samples obtained from 58 geographical locations in Europe, North Africa, and Asia show the molossinus Sry allele is restricted to Japan and the neighboring Asian mainland and confirm that Japanese M. m. molossinus mice were derived in part from a race of M. m. musculus from Korea or Manchuria. Sry polymorphisms, as illustrated by the molossinus Sry allele, can serve as molecular markers for studies on the evolution of wild M. musculus populations and can help determine the role sex determination plays in speciation.

Alleles↗
PubMed1994

[Diagnosis and management of pericardial cysts and diverticulum].

Eleven cases of pericardial cysts and 3 cases of pericardial diverticulum were reported. The prominent X-ray manifestations were a round or oval shape shadow with homogeneous density and smooth border in the mediastinum. In this series, the sizes of the lesions were 5-22 cm in diameter with averaged 9.9 cm. In the cases of pericardial diverticulum with a large base, fluoroscopic examination usually revealed that variation in contour of diventiculums during respiration and changing in position of the patients. Some aspects on the operation for pericardial cysts with secondary infection or adhering to the cardiac muscles were suggested in this paper.

Adolescent↗
PubMed1994

Elimination of the antianalgesic action of dynorphin A by spinal transsection in barbital-anesthetized mice.

Previous studies in mice demonstrate that, when dynorphin A (1-17) (Dyn A) is administered intrathecally (i.t.) or released spinally (by administration of clonidine or midazolam i.c.v.), i.t. morphine-induced analgesia was reduced. The present aim was to determine whether this antianalgesic action of Dyn A was the result of a spinal or supraspinal site of action by performing studies in spinally transsected mice. The approach was to use anesthetized, acute spinally transsected mice rather than chronic spinally transsected animals to avoid the need for long-term special animal care. The first part of the study evaluated four nonvolatile general anesthetic agents in an attempt to obtain one that did not affect the antianalgesic action of Dyn A, the release of Dyn A, the analgesic action of i.t. morphine (inhibition of the tail-flick response) or the tail-flick latency by itself. alpha-Chloralose (120 mg/kg), urethane (1 g/kg) and pentobarbital (20 or 40 mg/kg) given i.p. did not meet one or more of these requirements. Barbital 400 mg/kg i.p. met the requirements. In the second part of the study, barbital combined with halothane anesthesia was used to perform acute spinal transsection experiments. As in sham controls, the analgesic action of i.t. morphine was undiminished in spinally transsected animals, which indicated that the inhibition of the tail-flick response produced by i.t. morphine was on a spinal reflex response. On the other hand, spinal transsection produced a loss of the action of i.t. Dyn A to antagonize i.t. morphine-induced analgesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesia↗
PubMed1994

A study on cellular reactions and fibrogenic effects of mineral dusts.

In vivo cytotoxicity including cellular metabolic activity, lysozyme content and total protein content in rat bronchoalveolar lavage, capacity of interleukin-1 released from rat pulmonary cells and fibrogenic effects evaluated from rat lung dry weight, collagen content of the whole lung and pathological grading induced by mineral dust were assayed. The results showed that: (1) The relationship among in vivo cytotoxicity, interleukin-1 release, fibrogenic effects on the lung induced by mineral dusts correlated well with the free SiO2 content in mineral dusts in most (but not all) cases; (2) The biological harmful effects of mixed dusts were not simply the additive effect of single dust. In the group of WO3-SiO2 mixture, the fibrogenicity was mainly due to SiO2, tungsten trioxide (WO3) showed neither fibrogenic effect, nor significant potentiality to enhance SiO2 fibrogenicity, while in the group of SnO2-SiO2, SnO2 was suppressive to the effect of SiO2, although the contents of SiO2 in the two mixed dusts were similar.

Animals↗
PubMed1993

Decreased folylpolyglutamate synthetase expression: a novel mechanism of fluorouracil resistance.

HCT-8 cells become rapidly resistant to either 4-h (HCT-8/4hR) or 7-day (HCT-8/7dR) repeated exposures to fluorouracil (FUra). The HCT-8/7dR cells were studied in more detail to determine their mechanism of resistance to FUra. Thymidylate synthase activity, binding of 5-fluorodeoxyuridylate to thymidylate synthase, and incorporation of FUra into RNA were not different between the parental and resistant sublines. However, folylpolyglutamate synthetase activity was markedly decreased in this subline using tetrahydrofolate, 5,10-methylenetetrahydrofolate, and methotrexate as substrates. Northern blot analysis revealed decreased folylpolyglutamate synthetase mRNA expression in HCT-8/7dR cells as compared to HCT-8 cells. These findings indicate that low-dose continuous exposure schedules to FUra are cytotoxic primarily due to inhibition of thymidylate synthase and underscores the role of 5,10-methylenetetrahydrofolate polyglutamates in this inhibition.

Adenocarcinoma↗
PubMed1993

Salmonella reference collection B (SARB): strains of 37 serovars of subspecies I.

A reference collection of 72 strains representing 37 serovars of Salmonella subspecies I has been established for use in research on genetic and phenotypic variation in natural populations. Included are isolates of the host-adapted serovars S. choleraesuis, S. dublin, S. gallinarum, S. paratyphi A, S. paratyphi B, S. paratyphi C, S. pullorum, S. sendai, S. typhi and S. typhisuis, as well as strains of S. enteritidis, S. typhimurium, and other commonly recovered serovars with broad host ranges. The isolates were characterized by enzyme electrophoresis for allelic variation in 25 chromosomal genes and represent 71 distinctive multilocus genotypes (electrophoretic types or ETs). Genetic relationships among the ETs are indicated in an evolutionary tree constructed by the neighbour-joining method from a matrix of Nei's standard genetic distance.

Alleles↗
PubMed1993

Pentobarbital administered intracerebroventricularly antagonizes morphine-induced antinociception in mice.

The purposes were to show that pentobarbital administered intracerebroventricularly (i.c.v.) antagonized the antinociceptive action of morphine given intrathecally in the tail-flick test in mice, determine whether this antagonistic action involved spinal release of dynorphin A (Dyn A) and demonstrate whether the mechanism involved gamma-aminobutyric acid (GABA) receptors. Previously, it was shown that midazolam given i.c.v. antagonizes morphine-induced antinociception by release of Dyn A in the spinal cord. This antagonism by midazolam is reversed by a variety of benzodiazepine/GABAA receptor complex antagonists given i.c.v. The results indicated that the antagonistic action of pentobarbital given i.c.v. was not due to release of Dyn A based on presumptive tests for Dyn A release. 1) In the tail-flick test, the opioid receptor antagonists, naloxone and nor-binaltorphimine intrathecally, did not reverse the antagonism. 2) Pretreatment with dynorphin antiserum and morphine had no effect. The effect of pentobarbital was inhibited by a benzodiazepine receptor antagonist, flumazenil, given i.c.v. but not by a GABA antagonist, bicuculline s.c. or a chloride ion channel antagonist, picrotoxin, i.c.v. In contrast, the duration of loss of the righting reflex from systematically administered pentobarbital was shortened by bicuculline and picrotoxin but not by flumazenil. These results taken together with the previous results on midazolam suggested that the antagonistic action of pentobarbital on morphine-induced antinociception appeared to involve different GABA receptors from those involved in release of Dyn A by midazolam and those involved in the pentobarbital-induced loss of the righting reflex.

Animals↗