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Biomedical subjects

H Wu

Publications and source records attributed to H Wu.

At least 577 records · Page 32Linked to original sources
PubMed1997

Isotypic antibody responses of a population in an endemic area of schistosomiasis japonica and their epidemiologic significance.

The present study was designed to explore if there exists a correlation between predominant isotype-defined antibody levels and reinfection in low age groups of the population in an endemic area of schistosomiasis japonica in China. One hundred and thirty-eight individuals aged 3-25 years old were selected for serological investigations including the levels of IgG, IgG4, IgM and IgE, detected by ELISA with soluble egg antigen and soluble adult worm antigen. Results show that age is a determinant for SEA-specific IgG, IgG4, and IgE, and SWA-specific IgG and IgG4 antibody levels, which increased with age, and that SEA- and SWA- specific IgG4 antibody levels are risk factors of reinfection, ie, the risk of reinfection occurrence of the population with high level of SEA or SWA-specific IgG4 is 2.83 or 2.40 times, respectively, that with low level of SEA or SWA-specific IgG4, suggesting that in the endemic area of schistosomiasis japonica, there exists a possibility that in the population aged 3-25 years, SEA and SWA-specific IgG4 antibodies mediate a blocking immunity response.

Adolescent↗
PubMed1997

Preliminary observation on the metabolism in spontaneous hereditary diabetic Chinese hamster (Shanyi colony).

OBJECTIVE: To observe the changes of tissue lithium content and its relationship with glucose metabolism in spontaneous hereditary diabetic Chinese hamsters (SHDCH). METHODS: Twenty diabetic and ten normal Chinese hamsters were paired and separated randomly into four groups: controls (C), diabetics (D), controls treated with lithium carbonate (CT) and diabetics treated with lithium carbonate (DT). The lithium carbonate treatment was administrated with drinking water containing lithium carbonate (0.2 mg/ml). Blood glucose levels were determined at 0, 1, 3, 5, 6th month, and insulin levels at 1, 3, 6th month. The lithium contents in liver, kidney and muscles were determined at the end of 6th month, using wet digestion assay and ICP-AES. Concentrations of fructosamine, lactic acid, GPT, BUN were also evaluated. RESULTS: The data showed that in Group D the lithium levels in hepatic tissue were lower than in Group C (P < 0.05), and lithium contents in kidney and muscle also decreased. In Group DT, the lithium contents in tissues were higher than in Group D (P < 0.05) and similar to Group C. Blood glucose levels and fructosamine concentrations decreased while insulin and lactic acid levels did not alter significantly. GPT and BUN levels did not change in both Group CT and Group DT. CONCLUSIONS: There is lithium deficiency in hepatic, renal and muscular tissues from diabetic Chinese hamsters. Low-dose and six-month-treatments of lithium carbonate can improve tissue lithium deficiency and glucose metabolism, and do not damage liver and kidney functions.

Animals↗
PubMed1997

[Evaluation of optimal measuring site and index by QDR4500A for postmenopausal bone loss].

As the function of most bone mineral measuring machine is limited, either by single photon absorptiometry (SPA), dual photon absorptiometry (DPA), speed of sound (SOS), or dual energy x-ray absorptiometry (DEXA), it is hard to evaluate the best place and index of postmenopausal bone loss at many positions by one machine at the same time. So we used QDR4500A, one of the best advanced DEXA which has a good repeatability, to search the best place and index for postmenopausal bone loss. The results showed that (1) bone mineral density (BMD) was better than bone mineral content (BMC) and Area to reflect this kind of bone loss; (2) lumber BMD was a better place than the forearm BMD, total spine BMD and other places; and (3) midlateral L3, 4 BMD was a best index for postmenopausal bone loss.

Absorptiometry, Photon↗
PubMed1997

[Pre- and post-operative changes in serum levels of glycocholic acid and 3,5,3'-triiodothyronine and their clinical significance in patients with cholelithiasis].

Pre- and post-operative changes of serum glycine-conjugated cholic acid (CG) and 3,5,3'-triiodothyronine (T3) levels were observed in twenty-two patients with cholelithiasis. The increase of the levels of serum CG varied with the patients; the highest levels were seen in patients with cirrhosis. After operation, the levels of serum CG and T3 were decreased significantly in patients without cirrhosis. There was positive correlation between serum CG and T3 (r = 0.4667, P < 0.01). It is indicated that the lowering of serum CG after operation may be related to the lowering of serum T3; the significant increase of serum CG level is useful to the diagnosis of liver cirrhosis, which is more sensitive than Type B ultrasonography or routine examination of liver function.

Adult↗
PubMed1997

[Preliminary evaluation on bone mass of tibia by ultrasonic measurement].

The speed of ultrasound (SOS) in right middle tibia and bone mineral density (BMD) of left radius at the distal one-third were measured by ultrasonic measurement and single photoabsorptionmetry in 260 healthy individuals simultaneously. SOS of tibia was positively correlated with BMD of radius (r = 0.64). The peak bone mass of both measurements was at 33 to 36 years of age. Height was positively correlated with the SOS of tibia, while weight was positively correlated with SOS of female tibia, period of menopause negatively correlated with female's SOS of tibia. The concordance of SOS of tibia and BMD of radius in diagnosis of osteoporosis was 36.8%. The results suggest that ultrasonic measurement of tibia is an effective method of bone mass measurement.

Adolescent↗
PubMed1996

Kinetic and structural analysis of mutant CD4 receptors that are defective in HIV gp120 binding.

The T-cell antigen coreceptor CD4 also serves as the receptor for the envelope glycoprotein gp120 of HIV. Extensive mutational analysis of CD4 has implicated residues from a portion of the extracellular amino-terminal domain (D1) in gp120 binding. However, none of these proteins has been fully characterized biophysically, and thus the precise effects on molecular structure and binding interactions are unknown. In the present study, we produced soluble versions of three mutant CD4 molecules (F43V, G47S, and A55F) and characterized their structural properties, thermostability, and ability to bind gp120. Crystallographic and thermodynamic analysis showed minimal structural alterations in the F43V and G47S mutant proteins, which have solvent-exposed mutant side chains. In contrast, some degree of disorder appears to exist in the folded state of A55F, as a result of mutating a buried side chain. Real time kinetic measurements of the interaction of the mutant proteins with gp120 showed affinity decreases of 5-fold for G47S, 50-fold for A55F, and 200-fold for F43V. Although both rate constants for the binding reaction were affected by these mutations, the loss in affinity was mainly due to a decrease in on rates, with less drastic changes occurring in the off rates. These observations suggest the involvement of conformational adaptation in the CD4-gp120 interaction. Together, the structural and kinetic data confirm that F43V is a critical residue in gp120 recognition site, which may also include main chain interactions at residue Gly-47.

Binding Sites↗
PubMed1996

Structural studies of imidazole-cytochrome c: resonance assignments and structural comparison with cytochrome c.

Two-dimensional nuclear magnetic resonance spectroscopy (2D NMR) was used to obtain extensive proton resonance assignments of Im-cyt c complex which is a possible analog of a late folding intermediate of cytochrome c. Assignments were made nearly completely for the main-chain and the side-chain protons (all except Gly29). As starting points for the assignment of the Im-cyt c, a limited set of protons was initially assigned by use of 2D NMR magnetization transfer methods to correlated resonances in the Im-cyt c with assigned resonances in the native cyt c. The subsequent search focused on recognition of main-chain NOE connectivity patterns, with use of previously assigned residues to place NOE-connected segments within the amino acid sequence. The observed patterns of main-chain NOEs provided some structural information and suggested potentially significant differences between Im-cyt c and the native cyt c. Differences in NOEs involving side-chain protons were reported and analyzed. There was evidence for conformational changes induced by the breakage of Fe-S bond. It was concluded that the Im-cyt c had undergone a rearrangement of several regions forming the heme pocket of the protein. The structural understanding of these effects of the mutation may be essential to elucidate the changes in function and kinetic mechanism of cyt c folding.

Animals↗
PubMed1996

Stimulus-transcription coupling in pheochromocytoma cells. Promoter region-specific activation of chromogranin a biosynthesis.

To explore stimulus-transcription coupling in pheochromocytoma cells, we studied the biosynthetic response of chromogranin A, the major soluble protein co-stored and co-released with catecholamines, to chromaffin cells' physiologic nicotinic cholinergic secretory stimulation. Chromogranin A mRNA showed a time-dependent 3.87-fold response to nicotinic stimulation, and a nuclear run-off experiment indicated that the response occurred at a transcriptional level. Transfected chromogranin A promoter/luciferase reporter constructs were activated by nicotinic stimulation, in time- and dose-dependent fashions, in both rat PC12 pheochromocytoma cells and bovine chromaffin cells. Cholinergic subtype agents indicated that nicotinic stimulation was required. Promoter deletions established both positive and negative nicotinic response domains. Transfer of candidate promoter domains to a heterologous (thymidine kinase) promoter conferred region-specific nicotinic responses onto that promoter. A proximal promoter domain (from -93 to -62 base pairs) was activated in copy number- and distance-dependent fashion, and thus displayed features of a promoter element. Its activation was sufficient to account for the overall positive response to nicotine. Within this proximal region, a cAMP response element (CRE) was implicated as a major nicotinic response element, since a CRE point-gap mutation decreased nicotinic induction, transfer of CRE to a thymidine kinase promoter augmented the promoter's response to nicotine, and nicotine activated the CRE-binding protein CREB through phosphorylation at serine 133. We conclude that secretory stimulation of pheochromocytoma cells also activates the biosynthesis of the major secreted protein (chromogranin A), that the activation is transcriptional, and that a small proximal domain, including the CRE box, is, at least in part, both necessary and sufficient to account for the positive response to nicotine.

Animals↗
PubMed1996

Different collagenase gene products have different roles in degradation of type I collagen.

Vertebrate collagenases, matrix metalloproteinases (MMPs), cleave type I collagen at a single helical locus. We show here that rodent interstitial collagenases (MMP-13), but not human fibroblast collagenase (MMP-1), cleave type I collagen at an additional aminotelopeptide locus. Collagenase cDNAs and chimeric constructs in pET-3d, juxtaposing MMP-13 sequences amino-terminal to the active site in the catalytic domain and MMP-1 sequences carboxyl-terminal and vice versa, were expressed in Escherichia coli. Assays utilized collagen from wild type (+/+) mice or mice that carry a targeted mutation (r/r) that encodes substitutions in alpha1(I) chains that prevent collagenase cleavage at the helical locus. MMP-13 and chimeric molecules that contained the MMP-13 sequences amino-terminal to the active site cleaved (+/+) collagen at the helical locus and cleaved cross-linked (r/r) collagen in the aminotelopeptide (beta components converted to alpha chains). Human MMP-1 and chimeric MMP-1/MMP-13 with MMP-1 sequences amino-terminal to the active site cleaved collagen at the helical locus but not in the aminotelopeptide. All activities were inhibited by TIMP-1, 1,10-phenanthroline, and EDTA. Sequences in the distal two-thirds of the catalytic domain determine the aminotelopeptide-degrading capacity of MMP-13.

Amino Acid Sequence↗
PubMed1996

Morphology of axon collaterals of single climbing fibers in the deep cerebellar nuclei of the rat.

Projection of inferior olive (IO) neurons to the deep cerebellar nuclei (CN) was investigated in the rat by reconstructing single axons that were labeled with biotinylated dextran amine injected into the IO. All reconstructed terminal arborizations in the CN (n = 18) arose as collaterals from climbing fibers (CFs). One to six nuclear collaterals were given off from each of six CFs that were reconstructed along the nearly entire pathway backward from cortical terminal arborizations to the IO. Nuclear collaterals were much thinner (0.2-0.3 micron in diameter) than stem axons projecting to Purkinje cells (0.7-1.4 microns). The number of swellings per a single nuclear collateral ranged from 24 to 118 (n = 18). Terminal arborizations of nuclear collateral originating from a single CF spread for some hundreds of micrometers and occupied a localized portion within the CN.

Animals↗
PubMed1996

A slight asymmetry in the transbilayer distribution of lysophosphatidylcholine alters the surface properties and poly(ethylene glycol)-mediated fusion of dipalmitoylphosphatidylcholine large unilamellar vesicles.

Large, unilamellar vesicles (LUV) composed of dipalmitoylphosphatidylcholine (DPPC) were made asymmetric in L-alpha-lysopalmitoylphosphatidylcholine (LPC) either by adding a small amount (total mole fraction = 0.003) of LPC to their outer leaflets (LUV-LPCout) or by extracting a small amount from outer leaflets which already contained 0.0015 mol fraction LPC (LUV-LPCin). The slow rate of the transbilayer redistribution of LPC allowed the asymmetric vesicles to be characterized with regard both to their physical properties and to their ability to fuse in the presence of poly(ethylene glycol) (PEG). The fraction of LPC extractable with bovine serum albumin was taken as a measure of LPC transbilayer asymmetry. The ratio of LPC available to that unavailable to BSA extraction was 6 for LUV-LPCout and 0.3 for LUV-LPCin. These asymmetries could not be enhanced significantly by increasing the vesicle LPC content. Measurements of the mixing and leakage of vesicle contents showed that LUV-LPCin fused in the presence of 15% (w/w) PEG without loss of contents but that LUV-LPCout did not fuse in the presence of up to 35% PEG. Vesicles prepared from palmitoyloleoylphosphatidylcholine could also be made asymmetric in LPC, but did not fuse even in the presence of 30% PEG. Quasi-elastic light scattering revealed that LUV-LPCin aggregated at 25 degrees C except when swollen by an osmotic gradient while LUV-LPCout were much less likely to aggregate. Trapped volume determinations suggested that neither type of vesicle was perfectly spherical in shape, but no correlation was found between fusogenicity and vesicle shape. Measurements of the fluorescence properties of TMA-DPH and of C6-NBD-PC suggested that the interface region of the outer leaflet of LUV-LPCin was slightly less ordered and less well packed than that of LUV-LPCout. This slight perturbation of the external vesicle surface correlated with the ability of juxtaposed vesicle bilayers to fuse.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed1996

D2 and D1 dopaminergic activity of 7-OH-DPAT.

The D1 and D2 dopamine receptor agonist properties of 7-hydroxy-2-(N,N-di-n-propylamino) tetraline (7-OH-DPAT) was determined by investigating the effect of this compound on rat striatal acetylcholine (ACh) concentration and increase in cAMP formation in primary cerebellar granule cell cultures. 7-OH-DPAT at low doses (0.01 to 0.1 mumol/ kg) had no significant effect, and at high doses (0.3 to 30 mumol/kg) significantly (P < 0.01) increased striatal ACh levels. Likewise, quinpirole was found to significantly elevate ACh content. Pretreatment with haloperidol, a non-selective antagonist of the D2 family of receptors, significantly (P < 0.01) blocked 7-OH-DPAT- and quinpirole-induced increases in ACh. U-99194A, a D3 selective dopamine antagonist, had no significant effect on 7-OH-DPAT-induced increases in striatal ACh. However, raclopride, a D2 selective dopamine antagonist, completely blocked 7-OH-DPAT-induced elevations in ACh. 7-OH-DPAT in the mumolar range increased cAMP formation in granule cell cultures, and this effect was antagonized by SCH 23390, a D1 selective dopamine antagonist. The neurochemical study indicates that, at high doses, 7-OH-DPAT has both D1 and D2 agonist activities.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗
PubMed1996

Chromogranin A processing and secretion: specific role of endogenous and exogenous prohormone convertases in the regulated secretory pathway.

Chromogranins A and B and secretogranin II are a family of acidic proteins found in neuroendocrine secretory vesicles; these proteins contain multiple potential cleavage sites for proteolytic processing by the mammalian subtilisin-like serine endoproteases PC1 and PC2 (prohormone convertases 1 and 2), and furin. We explored the role of these endoproteases in chromogranin processing in AtT-20 mouse pituitary corticotropes. Expression of inducible antisense PC1 mRNA virtually abolished PC1 immunoreactivity on immunoblots. Chromogranin A immunoblots revealed chromogranin A processing, from both the NH2 and COOH termini, in both wild-type AtT-20 and AtT-20 antisense PC1 cells. After antisense PC1 induction, an approximately 66-kD chromogranin A NH2-terminal fragment as well as the parent chromogranin A molecule accumulated, while an approximately 50 kD NH2-terminal and an approximately 30 kD COOH-terminal fragment declined in abundance. Chromogranin B and secretogranin II immunoblots showed no change after PC1 reduction. [35S]Methionine/cysteine pulse-chase metabolic labeling in AtT-20 antisense PC1 and antisense furin cells revealed reciprocal changes in secreted chromogranin A COOH-terminal fragments (increased approximately 82 kD and decreased approximately 74 kD forms, as compared with wild-type AtT-20 cells) indicating decreased cleavage, while AtT-20 cells overexpressing PC2 showed increased processing to and secretion of approximately 71 and approximately 27 kD NH2-terminal chromogranin A fragments. Antisense PC1 specifically abolished regulated secretion of both chromogranin A and beta-endorphin in response to the usual secretagogue, corticotropin-releasing hormone. Moreover, immunocytochemistry demonstrated a relative decrease of chromogranin A in processes (where regulated secretory vesicles accumulate) of AtT-20 cells overexpressing either PC1 or PC2. These results demonstrate that chromogranin A is a substrate for the endogenous endoproteases PC1 and furin in vivo, and that such processing influences its trafficking into the regulated secretory pathway; furthermore, lack of change in chromogranin B and secretogranin II cleavage after diminution of PCl suggests that the action of PC1 on chromogranin A may be specific within the chromogranin/secretogranin protein family.

Animals↗
PubMed1996

2D-NMR studies of the effects of axial substitution on two helices in horse cytochrome c.

The sequential amino acids from Gly-1 to Cys-14 in the N-terminal segment and from Lys-88 to Glu-104 in the C-terminal segment of cytochrome c-imidazole complex (Im-cyt c) have been studied by two-dimensional nuclear magnetic resonance techniques. Resonance assignments for the main-chain and side-chain protons are reported. Qualitative interpretation of nuclear Overhauser enhancement data allows the secondary structure of the two segments to be described, which indicate the patterns of NOEs found are consistent with an alpha-helix between Val-3 and Cys-14 in the N-terminus, and between Lys-88 and Asn-103 in the C-terminus. Two alpha-helices are found to be maintained. Comparison of the long-range NOEs of Im-cyt c relative to the crystal structure of native cytochrome c reveals apparent conformational changes of some side-chains especially those close to heme pocket within the N- and C-terminal helices resulting from the binding of imidazole to iron by displacing native Met-80 side-chain. The explanation for ligand-induced changes within the N- and C-helices is therefore suggested.

Amino Acid Sequence↗
PubMed1996

Phospholipase D in platelets and megakaryocytic cells.

Phospholipase D (PLD) is stimulated in platelets by various agents. Phosphatidylcholine is the major substrate for PLD. This enzymatic pathway generates phosphatidic acid selectively. Guanine nucleotides also stimulate PLD in platelet membranes. Furthermore, tyrosine kinase may also be involved in platelet PLD regulation. It appears that multiple signals acting sequentially or in parallel converge on PLD. Among others, PLD has been proposed to play a role in platelet secretion and PLA2 regulation. PLD is also present in platelet percursor megakaryocytric cells and can be activated by platelet agonists. In these cells both PKC and G-proteins (e.g. Rho) may regulate PLD activity. The significance of PLD in megakaryocytes awaits investigation. These recent developments offer new avenues of research to further elucidate the biochemistry of platelet and megakaryocyte function.

Animals↗