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Biomedical subjects

W Ma

Publications and source records attributed to W Ma.

At least 181 records · Page 10Linked to original sources
PubMed1999

[An immunohistochemical and morphometric study of myoepithelial cells in salivary glands of human and experimental animals].

OBJECTIVE: To investigate whether differences exist between myoepithelial cells of human beings and experimental animals. METHODS: Myoepithelial cells(MeCs) of 8 kinds of experimental animals were studied immunohistochemically using muscle-acting-specific monoclonal antibody HHF35 and morphometrically using image-analysis. RESULTS: There were differences in mean proportional volumes of MeCs between human beings and experimental animals. The mean proportional volumes of mucous acini were more than those of serous acini except salivary glands of rodents. CONCLUSION: The mean proportional volume of MeCs in salivary glands associates with animal species and secretion of salivary glands.

Animals↗
PubMed1999

[Gene regulation studies on purine biosynthetic in Salmonella typhimurium IX. Mutation analysis of PUR box 2].

Two consensus bases C and G in 16 bp PUR box were directed mutated to G and A separately by PCR amplification. The binding function of PUR box carrying mutation with PUR protein were examined by gel retardation experiment. The results showed that the PUR box with above mutations could not bind with purR protein extracted from LT2. It proved that the two consensus bases C and G are necessary for PUR box binding with purR protein.

Bacterial Proteins↗
PubMed1999

HBV X protein (HBX) interacts with general transcription factor TFIIB both in vitro and in vivo.

OBJECTIVE: In order to demonstrate the binding of HBV X protein (HBX) with the general transcription factor TFIIB. METHODS: In vitro glutathion S-transferase (GST) resin Pull-Down assay and Far-Western Blotting assay, in vivo Co-immunoprecipition assay were used. RESULTS: The X199 (51-99) domain of HBX is reponsible for HBX binding to TFIIB. While the d10 domain (125-295) of TFIIB is required for TFIIB binding to HBX. When the two basic amino acids (K) at position 178 and 189 of TFIIB were substituted by neutral amino acids (L), the binding of TFIIB K178L and K189L to HBX was siginificantly reduced. When the the basic amino acids were substituted by the acidic amino acids (E), the binding of TFIIB K178E and K189E to HBX were almost lost. In vitro results of HBX binding to TFIIB were further confirmed by in vivo co-immunoprecipitation assay. Our results also indicated that the Woodchuck hepatitis virus X protein (WHX) interacts with TFIIB. CONCLUSION: These results suggested that the communication between HBX and general transcription factor TFIIB is one of the mechanisms which account for its transcriptional transactivation.

Binding Sites↗
PubMed1999

[A new method for the determination of captopril].

Captopril was determined in medicine by a new photometric method based on the color formation of Cu(I)-neocuproine complex from neocuproine and Cu(II) which could be reduced by captopril. The method was simple and rapid, and the results obtained were in agreement with those of tungsten blue method.

Antihypertensive Agents↗
PubMed1999

[Study on catalytic spectrophotometic determination of nitrite with catechol violet system].

A new sensitive method for the determination of trace nitrite was developed, based on nitrite as a catalyst. The optimum kinetic conditions were discussed and the concentration of nitrite was linear in the rang of 0.2-3.5 microg/10mL. The proposed method is simple, rapid, selective and convenient to determine nitrite in water and vegetables with good results.

Catalysis↗
PubMed1999

[Determination of analginum in medicine by ironic rhodanate spectrophotometry].

Analginum in preparations was determined by the ironic rhodanate fading spectrophotometric method, based on Fe3+ reduced into Fe2+ by analginum and reacting on potassium rhodanate. The obtained results were in agreement with those of the iodine titration method and the ultraviolet photometric method.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

[Study on the new determination of analginum].

Analginum in medicine was determined by a new photometric method based on the color formation of Fe(II)-alpha,alpha'-dipyridine complex from alpha,alpha'-dipyridine and Fe (III) which could be reduced by analginum. The method was simple and rapid, and the results obtained were in agreement with those of iodine titration method and ultraviolet photometric method.

Analgesics, Non-Narcotic↗
PubMed1999

[Measurement of aluminum (III) in crops by synergistic chromatic reaction].

In the presence of OP, a sensitive color reaction of aluminum (III) on pyrocatechol violet and rhodamine 6G has been studied. In a NH4Ac-HAc (pH = 6.5) medium, aluminum (III) ions form an ions-associate complex with pyrocatechol violet and rhodamine 6G. The composition of the complex is Al (III) : PV: Rh6G = 1 : 2 : 4. The maximum absorption of the ions-associate complex is at 580 nm with an apparent molar absorptivity of 6.8 x 10(4) L x mol(-1) x cm(-1). Beer's law is obeyed in the range of 0-7 microg/25 mL of aluminum. The method is highly selective and has been applied to the determination of trace aluminum in crops with satisfactory results.

Aluminum↗
PubMed1999

[Study on the new method for spectrophotometric determination of potassium iodate in salt].

A new simple, fast and sensitive spectrophotometric method in water phase for the determination of micro amount of potassium iodate in salt was studied. The method is based on chromogenic reaction of crystal violet on I3- produced from potassium iodate reacting on KI in HCl medium and using OP as the solubility-increasing reagent. When applying the proposed method to determining potassium iodate in salt, the results obtained were in agreement with those of ultrovilet spectrophotometry.

Flavoring Agents↗
PubMed1999

[Study on the synergistic coloration of tin (II) with pyrocatechol violet and rhodamine B and its application].

In the presence of PVA, a sensitive color reaction of tin (I ) on pyrocatechol violet and rhodamine B has been studied. In a NaAc-HAc (pH = 5.0) medium, tin(II) ions form an ions-associate complex with pyrocatechol violet and rhodamine B. The composition of the complex is Sn (II): PV : RhB = 1 : 2: 4. The maximum absorption of the ions-associate complex is at 560 nm with an apparent molar absorptivity of 1.18 x 10(5) L x mol(-1) x cm(-1). Beer's law is obeyed in the range of 0-15 microg/25 mL of tin. The method is highly selective and has been applied to the determination of trace tin in some objects with satisfactory results.

Benzenesulfonates↗
PubMed1998

Galanin expression in neuropathic pain: friend or foe?

We investigated a possible link between galanin expression and evoked pain accompanying painful partial sciatic nerve lesions. Increased galanin immunoreactivity (IR) in the dorsal horn, in gracile nucleus, and in sensory neurons following chronic constriction injury (CCI) compared to complete sciatic transection suggested a facilitatory role in thermal and mechanical hypersensitivity (allodynia). We therefore investigated the effects of endogenous interleukin-6 (IL-6) and nerve growth factor (NGF) on allodynia and neuropeptide expression. IL-6 knockout mice showed decreased allodynia and galanin-IR compared to wild-type mice, but also decreased substance P (SP)-IR in the dorsal horn. Anti-NGF-treated rats with CCI also showed decreased allodynia and SP-IR, but increased galanin-IR in the dorsal horn. These results suggest that evoked pain is more tightly linked to SP than to galanin expression. If galanin's effects are inhibitory as the bulk of the literature suggests, its effects are subordinate to those of SP and to other changes following CCI.

Animals↗
PubMed1998

Central neuronal synapse formation on micropatterned surfaces.

Controlling synapse formation is a key to patterning of neurons into functional circuits and networks in vitro. However, the process of synapse formation among neurons grown on artificial surfaces is relatively unstudied. We cultured embryonic hippocampal cells on trimethoxysilylpropyl-diethylenetriamine (DETA) and tridecafluoro-1, 1,2,2-tetrahydrooctyl-1-dimethylchlorosilane (13F), and on patterns composed of DETA lines separated by 13F spaces. For comparison, neurons were concurrently plated on surfaces coated with uniform poly-d-lysine (PDL). Pre- and postsynaptic specializations were identified by immunostaining for synapsin I and microtubule-associated protein-2 (MAP-2). Spontaneous (SPCs) and evoked (EPCs) postsynaptic currents were recorded using dual patch-clamp techniques. We found that DETA promoted synapse formation, whereas evidence for synapse formation on 13F was barely detected. MAP-2+ neuronal soma and rapidly growing dendrites were co-localized with synapsin I puncta faithfully along DETA lines. The expression of synapsin I puncta, and MAP-2+ soma and dendrites correlated well with the appearance of SPCs. Synapsin I, MAP-2 and SPCs emerged together at days 3-4 and increased at day 7, when EPCs appeared. Synaptic signals occurring during 4-7 days in culture were all GABAergic. These results indicate that fully functional synapses are formed on silane surfaces, demonstrating the suitability of patterned silane surfaces for organizing synapse formation in vitro.

Animals↗
PubMed1998

The G protein G alpha12 stimulates Bruton's tyrosine kinase and a rasGAP through a conserved PH/BM domain.

Heterotrimeric guanine-nucleotide-binding proteins (G proteins) are signal transducers that relay messages from many receptors on the cell surface to modulate various cellular processes. The direct downstream effectors of G proteins consist of the signalling molecules that are activated by their physical interactions with a G alpha or Gbetagamma subunit. Effectors that interact directly with G alpha12 G proteins have yet to be identified. Here we show that G alpha12 binds directly to, and stimulates the activity of, Bruton's tyrosine kinase (Btk) and a Ras GTPase-activating protein, Gap1m, in vitro and in vivo. G alpha12 interacts with a conserved domain, composed of the pleckstrin-homology domain and the adjacent Btk motif, that is present in both Btk and Gap1m. Our results are, to our knowledge, the first to identify direct effectors for G alpha12 and to show that there is a direct link between heterotrimeric and monomeric G proteins.

Agammaglobulinaemia Tyrosine Kinase↗
PubMed1998

Regulation of cardiomyocyte apoptotic signaling by insulin-like growth factor I.

Apoptosis is regulated by specific intracellular signaling pathways. The development of cardiomyopathy involves the apoptosis of cardiomyocytes; however, the details of their apoptotic signaling are not yet known. Insulin-like growth factor I (IGF I) is an important survival growth factor for myocardium and other tissues, but the effects of IGF I on apoptotic signaling remain largely unknown. To study apoptotic signaling pathways in cardiomyocytes and to understand IGF I actions on the apoptotic signaling of cardiac muscle cells, we have defined the effects of IGF I on Bcl-2, Bax, caspase 3, DNA fragmentation, and cell survival in primary cardiomyocytes. Compared with Bax levels, the levels of Bcl-2 were found to be quite low in these cells. Serum withdrawal and doxorubicin reduced cell viability, increased fragmentation of DNA, increased cellular contents of Bax, and activated caspase 3. IGF I enhanced cell viability, suppressed DNA fragmentation, attenuated Bax induction, and suppressed caspase 3 activation. The levels of Bcl-2-associated Bax were increased after serum withdrawal and incubation with doxorubicin and were reduced by IGF I. Thus, cardiomyocyte apoptosis induced by serum withdrawal and doxorubicin likely results, in part, from the induction of Bax and activation of caspase 3, but IGF I may inhibit cardiomyocyte apoptosis by attenuating Bax induction and caspase 3 activation. These findings provide new insight into the mechanisms of cardiomyocytes apoptosis and may help elucidate how IGF I modulates apoptotic signaling in cardiac muscle.

Animals↗
PubMed1998

Human endothelial cells effectively costimulate cytokine production by, but not differentiation of, naive CD4+ T cells.

We compared costimulatory signals provided by human endothelial cells (ECs) to those provided by conventional bone marrow-derived APCs, i.e., peripheral blood-adherent mononuclear cells (PBAMCs), by measuring their effects on cytokine production by naive or memory CD4+ T cells stimulated by PHA. In these assays, ECs effectively costimulate secretion of IL-2, IFN-gamma, and IL-4 from both naive and memory CD4+ T cells, quantified by ELISA or intracellular cytokine staining. ECs, which lack B7 molecules, use predominantly leukocyte-function associated Ag 3 (LFA-3) to provide costimulation. ECs are comparable to or better than PBAMCs, which use both the LFA-3 and B7 molecules, at costimulating IL-2 and IL-4 production. ECs are less effective than PBAMCs at costimulating IFN-gamma production by naive T cells. ECs do not secrete IL-12, and addition of exogenous IL-12 enables ECs to costimulate IFN-gamma at a level comparable to that observed with PBAMCs. ECs do not promote differentiation of naive T cells to Th1-like cells, whereas PBAMCs do. Again, addition of exogenous IL-12 enables ECs to do so. Transfection of ECs to express B7-1 or B7-2 is less effective than IL-12 supplementation for restoring these responses. These experiments suggest that a deficiency in costimulation due to lack of B7 molecule expression does not fully explain the inability of ECs to activate resting naive CD4+ T cells.

Adjuvants, Immunologic↗
PubMed1998

Microlithographic determination of axonal/dendritic polarity in cultured hippocampal neurons.

High resolution substrates, created using patterned self-assembled monolayers, are shown to direct axonal and dendritic process extension at the level of a single hippocampal neuron. Axons and dendrites were identified using morphological characteristics and immunocytochemical markers. Patterns were formed on glass coverslips from a co-planar monolayer of cell adhesive aminosilanes and non-adhesive fluorinated silanes. On patterned surfaces, the percentage of the total number of cells attached to the 0.71 mm2 substrate field with compliance to the 25-micron diameter 'somal adhesion site' reached 41 +/- 7% (mean +/- S.D., 428 cells counted). A total of 76 +/- 11% of cells that adhered to a somal attachment site developed a lone process > or = 100 microns oriented in the direction of the continuous aminosilane pathway which was shown to express axonal markers. Cells on either the fluorinated silane, which is non-permissive for neurite outgrowth, or localized on an aminosilane region only 5 microns wide failed to extend major processes. This approach is amenable to a variety of industry standard fabrication techniques and may be used to study the role of fine scale spatial cues in neuronal development and synapse formation.

Animals↗
PubMed1998

GABA receptor subunit mRNA expression in brain of conflict, yoked control and control rats.

Animal conflict models have been used for years as a preclinical screen for predicting anxiolytic therapeutic efficacy. Anxiolytics, including benzodiazepines, increase punished responding. This suggests that the punished behavior may be mediated by the GABA receptor. To evaluate this hypothesis, we performed in situ hybridization histochemistry studies of GABA receptor subunits (alpha1-alpha4) and synthetic enzymes glutamic acid decarboxylase (GAD65 and GAD67) in four groups of rats: conflict (punishment), yoked controls (rats shocked without conflict training history), fixed interval only controls (rats that worked for food but were not shocked) and untreated controls. With conflict behavioral training, bilateral reduction of mRNA for the GABAA alpha1 subunit was seen relative to controls in the cortex, thalamus and hippocampus. In contrast, alteration of alpha2 mRNA levels appeared only in the yoked control group, with increased levels seen in the thalamus and cortex and decreased levels in the hippocampus. There were no differences in the alpha2 mRNA level between the control and the conflict behavioral trained animals. Further, no significant differences were found between groups in the mRNA levels for the alpha3 subunit, alpha4 subunit, GAD65, and GAD67. These results suggest that the behaviors related to conflict and uncontrollable aversive stimuli (yoked control group) are accompanied and perhaps mediated by selective changes in the GABAA alpha1 or alpha2 subunits, respectively. These findings highlight the potential usefulness of the conflict model as a means of elucidating the biological underpinnings of anxiety disorder. Published by Elsevier Science B.V. All rights reserved.

Animals↗