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Biomedical subjects

H Yang

Publications and source records attributed to H Yang.

At least 901 records · Page 50Linked to original sources
PubMed1993

The effect of reconstruction after subtotal gastrectomy on release of vasoactive intestinal peptide.

To avoid dumping after Billroth gastrectomy, we designed pylorus and antroseromuscular-flap preserving subtotal gastrectomy (PAFPG). The mean maximal plasma level of VIP (vasoactive intestinal peptide) in PAFPG after oral hypertonic glucose was close to that in the control. Compared with PAFPG group, the plasma VIP concentrations after hypertonic glucose ingestion in BI and BII group were significantly higher, and the concentration of plasma VIP in dumpers was significantly higher than that in non-dumpers after BI or BII gastrectomy. The results suggest that the amount of VIP release is related to the type of reconstruction after gastrectomy.

Dumping Syndrome↗
PubMed1993

[Determination of serum pancreatic polypeptide and its clinical significance in patients with end state renal failure].

Serum levels of pancreatic polypeptide (SPP) responding to 75g glucose (oral) challenge were observed in 27 patients with end state renal failure (ESRF) and 27 normal subjects as a control. The results showed that the levels of SPP were significantly higher in ESRF patients than in normal subjects. Dialysis therapy seemed to have no effect on the levels of SPP. The elevated levels of SPP could return to normality after kidney transplantation. There was no positive correlation between the levels of SPP, the blood sugar, and the serum insulin. It is suggested that kidneys are the important sites for the metabolism of PP. The elevated SPP concentration in patients with ESRF may result from their renal failure, and may contribute to some gastrointestinal symptoms which are frequently associated with ESRF.

Adult↗
PubMed1993

[Study on determination of gentamycin by enhanced chemiluminescent immunoassay].

Gentamycin was determined by solid antigen competition inhibition method of chemiluminescet immunoassay, in which luminol-(p-hydroxydiphenyl)-H2O2 was used a the chemiluminescence system and p-hydroxydiphenyl as the chemiluminescent enhancer. Solid antigen was synthesized by a method in which gentamycin was immobilized covalently on microcrystalline cellulose previously activated by 1,1'-carbonyldiimidazole. The rabbit anti-gentamycin IgG and the HRP-donkey anti-rabbit IgG were used as the first antibody and labelled second antibody, respectively. The linear range of the gentamycin (with blank serum) was 0.03-1 micrograms/tube and the correlation coefficient of the log-log regression equation [r[ was 0.981 +/- 0.016 with a limit of detection 3.3-11.4 ng/tube and the recovery of gentamycin 88.2 +/- 4.5%.

Biphenyl Compounds↗
PubMed1993

[Expression of left ventricular ANF-gene in rat with cardiac hypertrophy].

Plasma concentration of ANF and expression of left ventricular ANF-gene in rats with cardiac hypertrophy induced by abdominal aortic partial ligation were analyzed by RIA and Northern blot respectively. Results showed that plasma concentration of ANF and level of left ventricular ANF-mRNA in cardiac hypertrophic rats increased markedly, indicating that the cardiac load may induce transcription and expression of left ventricular ANF-gene. This effect could be potentiated by intracellular calcium modulator taurine and inhibited by vasodilator hydralazine.

Animals↗
PubMed1993

CD44 is not directly involved in the binding of lymphocytes to cultured high endothelial cells from peripheral lymph nodes.

The Ager assay was adapted to a porcine lymphocyte-rat high endothelial cell (HEC) system. Using this in vitro assay, the role of porcine CD44 in lymphocyte binding to HEC was examined. The results show that the presence of soluble CD44 molecules did not inhibit the binding of porcine lymphocytes to the cultured rat HEC. Treatment of lymphocytes with anti-CD44 monoclonal antibodies (mAb), or with papain, which removes a 45,000 MW peptide from the intact CD44 molecule, did not inhibit the binding. Binding to the rat HEC did not induce modulation of CD44 molecules on the cell surface. Furthermore, modulation of the CD44 molecule by biotinylated anti-CD44 antibody followed by streptavidin-phycoerythrin, which had caused the molecule to cap on the cell surface, did not prevent the cells binding to the HEC. Similarly, cells denuded of CD44 by anti-CD44 antibody retained the capacity to bind to HEC. Moreover, the binding cells were mainly those which had been stripped of CD44 by the antigenic modulation. It is concluded that CD44 is not directly involved in the binding of lymphocytes to the cultured HEC from peripheral lymph nodes (PLN).

Animals↗
PubMed1993

Isolation and characterization of the soluble and membrane-bound porcine CD44 molecules.

Porcine CD44 was identified by the cross-reactive anti-human CD44 monoclonal antibody (mAb) Hermes-1. Material which inhibited the Hermes-1 mAb binding to porcine lymphocytes was found in porcine intestinal efferent lymph and demonstrated to be a soluble form of porcine CD44. A protocol using non-affinity techniques was established to isolate this material from porcine lymph. The isolated soluble CD44 molecule consists of a single peptide with an apparent MW of about 50,000, containing the Hermes-1 epitope. The soluble and membrane-bound forms of porcine CD44 were also affinity purified and characterized. The soluble CD44 preparation comprised a major component of 48,000-70,000 MW peptide and a minor band of 120,000 MW. The membrane-bound CD44 preparation contained a 90,000 MW major and a 120,000 MW minor component. Both the major components of the soluble and membrane-bound forms of porcine CD44 contained N-linked glycosylation. The 48,000-70,000 MW component of the soluble CD44 molecules consisted of two subsets discriminated by their binding capacity for lentil lectin and a slight difference in molecular weights. Soluble CD44 molecules were also identified in the sera of sheep, goats, horses, dogs and humans. Like the porcine counterpart, these molecules could be enriched by anion-exchange chromatography, suggesting that they have similar biochemical properties.

Amino Acids↗
PubMed1992

Differential utilization of poly (A) signals between DHFR alleles in CHL cells.

The Chinese hamster cell line, DC-3F, is heterozygous at the DHFR locus, and each allele can be distinguished on the basis of a unique DNA restriction pattern, protein isoelectric profile and in the abundancy of the DHFR mRNAs it expresses. Although each allele produces four transcripts, 1000, 1650 and 2150 nucleotides [corrected] in length, the relative distribution of these RNAs differs for each; the 2150 nt mRNA represents the major (60%) species generated from one allele, while the 1000 nt mRNA is the major species generated from the other. The allele that predominantly expresses the 2150 nt transcript is preferentially overexpressed when DC-3F cells are subjected to selection in methotrexate. We have analyzed the 3' ends of both DHFR alleles and have found that the three major mRNAs arise by readthrough of multiple polyadenylation signals. A four base deletion in one allele changes the consensus polyadenylation signal AAUAAA to AAUAAU, resulting in the utilization of a cryptic polyadenylation signal lying 21 bp upstream. Surprisingly, this mutation in the third polyadenylation signal appears to affect not only the utilization of this signal, but also the efficiency with which the first signal, located 1171 bp upstream from the third site, is utilized.

Alleles↗
PubMed1992

Thyrotropin-releasing hormone analog injected into the raphe pallidus and obscurus increases gastric contractility in rats.

The present study was performed to investigate the influence of the chemical stimulation of medullary raphe nuclei by the stable TRH (thyrotropin-releasing hormone) analog, RX 77368, on gastric contractility. Urethane-anesthetized rats were acutely implanted with miniature strain gauge force transducers on the corpus of the stomach for continuous recording of gastric contractility. Traces were analyzed by computer. Microinjections of vehicle or RX 77368 into the raphe pallidus or raphe obscurus were performed using pressure injection of 50 nl through glass micropipettes 30 min following basal recording of gastric contractility. RX 77368 (0.7-77 pmol) dose dependently stimulated gastric contractility when microinjected into the raphe pallidus and raphe obscurus. The stimulation of gastric contractions induced by microinjection of RX 77368 (77 pmol) into these raphe nuclei was completely blocked by vagotomy and prevented (raphe obscurus) or reduced (raphe pallidus) by atropine. RX 77368 (7.7-77 pmol) microinjected into the inferior olive, pyramidal tract, medial lemiscus was ineffective. These results demonstrate that chemical stimulation of the raphe pallidus and obscurus by RX 77368 stimulates gastric contractility through vagal and muscarinic pathways. These data suggest a role for medullary raphe nuclei in the central vagal regulation of gastric contractility.

Animals↗
PubMed1992

Synthesis and antiviral activity of methyl derivatives of 9-[2-(phosphonomethoxy)ethyl]guanine.

A number of methyl derivatives of 9-[2-(phosphonomethoxy)ethyl]guanine (PMEG, 1) have been synthesized and tested in vitro for anti-herpes and anti-human immunodeficiency virus (HIV) activity. Among these analogues, (R)-2'-methyl-PMEG [(R)-3] and 2',2'-dimethyl-PMEG (7) demonstrated potent anti-HIV activity in the XTT assay with EC50 values of 1.0 and 2.6 microM, respectively. The corresponding (S)-2'-methyl-PMEG [(S)-3] was found to be less potent against HIV. In addition, the (R) and (S) enantiomers of 9-[3-hydroxy-2-(phosphonomethoxy)propyl]guanine (HPMPG, 8) were prepared for comparison of biological activity, and shown to be active and equipotent against herpesviruses, but inactive against HIV.

Antiviral Agents↗
PubMed1992

The A alpha mating locus of Schizophyllum commune encodes two dissimilar multiallelic homeodomain proteins.

The A alpha mating locus is one of four multiallelic loci that govern sexual development in the basidiomycete fungus Schizophyllum commune. We have determined the nucleotide sequence encoding three A alpha mating types, A alpha 1, A alpha 3, and A alpha 4. We have found that the locus for A alpha 3 and A alpha 4 consists of two genes: Y and Z. The locus for A alpha 1 encodes only one gene, Y. The Z polypeptides encoded by different alleles exhibit 42% identity. The Y polypeptides exhibit 49-54% identity. The finding that the deduced Z and Y polypeptides have homeodomain motifs suggests that these polypeptides may be DNA-binding regulatory proteins that control the expression of developmental genes. The deduced Z polypeptide also has acidic regions that might be functionally analogous to the acidic regions in yeast GAL4 and GCN4 that activate transcription. The Y polypeptide has a serine-rich region and a basic region that shows some identity to the lysine-rich region of H1 histones.

Alleles↗
PubMed1992

Medium effects on the kinetics of human plasmin.

Effects of water-miscible organic solvents added to an aqueous buffer on the activity of several serine proteinases were studied. Plasmin in particular showed a dramatic difference in activity depending on the hydrophobicity of the added organic solvent through a combination of Km and kcat effects. An inverse linear correlation between the polarity of the mixed solvent and the log (kcat/Km) of plasmin activity was observed for both H-D-Val-Leu-Lys-p-nitroanilide (S-2251) and pro-urokinase as the substrate. The activity of plasmin was less dependent on the polarity of the added solvent when other chromogenic substrates were employed that contained an arginyl residue in the P1 site.

Amino Acid Sequence↗
PubMed1992

Human high molecular weight melanoma-associated antigen (HMW-MAA) mimicry by mouse anti-idiotypic monoclonal antibody MK2-23: induction of humoral anti-HMW-MAA immunity and prolongation of survival in patients with stage IV melanoma.

Twenty-five patients with stage IV melanoma were immunized with the mouse anti-idiotypic monoclonal antibody (mAb) MK2-23 (2 mg per injection), which bears the internal image of the determinant defined by anti-HMW-MAA mAb 763.74. Two patients were inevaluable, since they did not complete 4 weeks of therapy. Only 14 patients developed antibodies that were shown by serological and immunochemical assays to recognize the same or spatially close determinant as the anti-HMW-MAA mAb 763.74 and to express the idiotope defined by mAb MK2-23 in their antigen-combining sites. Side effects that are likely to be caused by bacillus Calmette-Guérin present in the immunogen consisted of erythema, induration, and ulceration at the sites of the injections. Occasionally, patients complained of flu-like symptoms, arthralgias, and myalgias. Three of the patients who developed anti-HMW-MAA antibodies achieved a partial response. It consisted of a decrease in the size of metastatic lesions and lasted 52 weeks in 1 patient and 93 weeks in the other 2 patients. Survival of the 14 patients who developed anti-HMW-MAA antibodies was significantly (P = 0.0003) longer than that of the 9 patients without detectable humoral anti-HMW-MAA immunity development. In the multivariate analysis, such an association between development of anti-HMW-MAA antibodies and survival prolongation was still significant (P = 0.001) after adjustment for difference in performance status, the only confounding factor found to be significantly related to survival. Lastly, a significant (P = 0.03 by likelihood ratio test) interaction between anti-HMW-MAA antibodies and patients' performance status was found, since the prolongation of survival associated with anti-HMW-MAA antibodies was more marked in patients with a performance status of less than or equal to 70% than in those with a higher one. These results suggest that anti-idiotypic mAb MK2-23 may represent a useful immunogen to implement active specific immunotherapy in patients with melanoma.

Antibodies, Anti-Idiotypic↗
PubMed1992

Risk factors for gallstone formation during rapid loss of weight.

Risk factors for the development of gallstones during rapid weight loss were assessed in 457 subjects who entered a weight control program (520 kcal/day). Absence of gallstones in these subjects was documented by ultrasonography prior to entry into the study. Ultrasonography was performed again at 16 weeks on the subjects who remained in the study (N = 248). The incidence of gallstones by 16 weeks of rapid weight loss was 10.9% (27/248). Most factors associated with gallstones in the general population, eg, older age, female gender, parity, positive family history, etc, were not associated with gallstones in this population. The risk factors for developing gallstones included increased initial body mass index [weight (kg)/height (m)2], amount of body mass index loss, and serum triglyceride levels. The positive predictive value of these risk factors was 75%, but the sensitivity was only 12%. These observations indicate that risk factors for the development of gallstones during rapid weight loss are probably different from those in the general population. The factors identified by this study are useful in predicting patients at high risk for gallstones. However, since only a minority of gallstones that form can be predicted, further study is needed to identify additional factors that will improve our ability to predict gallstone formation.

Adult↗
PubMed1992

Cryoinjury in human granulocytes and cytoplasts.

Although most isolated cells can be successfully cryopreserved, human granulocytes have little functional recovery after cryopreservation, even under optimized conditions. Cytoplasts, which are vesicles created from human granulocytes by depletion of organelles including granules and the nucleus, can carry out some of the complex functions of the parent granulocyte such as phagocytosis of bacteria, even after cryopreservation. Human granulocytes and cytoplasts were used in this comparative study of low-temperature responses to assess the relative importance of the plasma membrane and the granules in cryoinjury to human granulocytes. Boyle-van't Hoff plots of cell volume as a function of the reciprocal of osmolality showed that granulocytes and cytoplasts have similar osmometric behavior and equivalent osmotically inactive fractions. The hydraulic conductivities were also similar, indicating that the osmotic properties of the plasma membrane and cytoplasm were retained during preparation of the cytoplasts. Assessment of membrane integrity using fluorescein diacetate after graded freezing stresses showed that the low-temperature responses of cytoplasts were similar to those of human lymphocytes and hamster fibroblasts, with recoveries much higher than those of human granulocytes, particularly after post-thaw incubation at 37 degrees C. The results indicate that the plasma membrane is not the primary site of injury to granulocytes during freezing and thawing, and suggest that activation of cytoplasmic elements, such as granules, may constitute the early events in cryoinjury to human granulocytes. These studies have significance in approaches to the cryopreservation of granulocytes and other types of cells, such as platelets, with increased sensitivity to the conditions encountered during freezing and thawing.

Cell Membrane↗