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Biomedical subjects

H Xu

Publications and source records attributed to H Xu.

At least 667 records · Page 37Linked to original sources
PubMed1994

A dual block to cell cycle progression in HL60 cells exposed to analogues of vitamin D3.

The physiologically active form of vitamin D3, 1,25-dihydroxy-vitamin D3 (1,25(OH)2D3), induces differentiation of several types of myeloid leukaemia cells. The acquisition of monocyte-like phenotype is accompanied by slower progression through the cell cycle, and G1 block has been reported to be the basis of this effect. It is shown here that human promyelocytic leukaemia HL60 cells treated with analogues of vitamin D3 which are potent inducers of monocytic differentiation have an additional cell cycle block. Exposure to 10(-7) M 1,25(OH)2D3 or 1,25-(OH)2-16-ene-D3 resulted in monocytic differentiation and the expected G1 block evident at approximately 48 h in a rapidly differentiating variant of HL60 cells (HL60-G), and at 96 h in the more slowly differentiating HL60-240 cells. In addition, a G2+M block was noted at approximately 72 h in HL60-G and HL60-240 cells. Exposure to vitamin D3 analogues also markedly increased the number of dikaryons, suggesting that cytokinesis was impaired more than karyokinesis. Treatment with a third analogue 25-hydroxy-16,23-diene-D3 produced little differentiation and had minimal effects on the cell cycle parameters. These findings indicate that vitamin D3 analogues regulate cell proliferation by control of the transition of G1 and G2+M phases, reminiscent of the cdc2/CDK2 type of cell cycle control.

Antineoplastic Agents↗
PubMed1994

Low molecular weight IgM and CD5 B lymphocytes in rheumatoid arthritis.

OBJECTIVES: To evaluate the role of low molecular weight (LMW) IgM and CD5 B cells in rheumatoid arthritis (RA) and to explore the possibility that LMW IgM is derived selectively from this subset of B cells. METHODS: LMW IgM in sera and culture supernatants was detected by a sensitive immunoblot technique with an enhanced chemiluminescence detection system. CD5 B cells were determined by FACScan cytometry. In vitro studies were established in culture plates containing pokeweed mitogen with or without 2-mercaptoethanol (2-ME). Supernatants were obtained from CD5 positive hybridomas and CD5 negative hybridomas. Other immunological indices were measured by laser nephelometry. RESULTS: Circulating LMW IgM was detected in all rheumatoid patients with significantly higher levels being observed in sero-positive patients. LMW IgM correlated significantly with total IgM and RF. Peripheral blood mononuclear cells (PBMC) from the majority of the patients with RA secreted LMW IgM in vitro as did mononuclear cells from a synovial fluid sample. The addition of low concentrations of 2-ME to the culture medium enhanced the proportions of secreted monomeric IgM. In contrast, PBMC from healthy subjects secreted only trace quantities of LMW IgM. In RA no significant correlations were observed between CD5 B cells and LMW IgM and RF. LMW IgM could be detected in the supernatants from both CD5+ and CD5- B cell lines. Finally, CD5 B cells were not significantly elevated in RA and levels remained constant over time. CONCLUSION: LMW IgM exists in high concentrations in RA sera and synovial fluid. Serum level correlates with RF and IgM. In vitro studies have suggested that the occurrence of LMW IgM may be due to an intrinsic defect(s) in the assembly of the IgM pentameric molecule. LMW IgM is unlikely to be derived solely from CD5 B cells.

Adult↗
PubMed1994

Effect of l-glutamine on pulmonary hypertension in the perfused rabbit lung.

The effects of l-glutamine on pulmonary hypertension in the isolated perfused rabbit lung were investigated. Pulmonary hypertension was produced by the thromboxane-A2 mimetic U46619. l-Glutamine at a dose of 0.04 mM produced a sustained increase in pulmonary artery pressure (PAP) and subsequent administration of an equimolar dose of l-arginine did not affect PAP. l-Glutamine at a dose of 0.5 mM transiently increased PAP, which then decreased to baseline (pre-glutamine) values. When endogenous nitric oxide (NO) synthesis was inhibited with NG-nitro-l-arginine methylester, l-glutamine at a dose of 0.04 mM decreased PAP. These results demonstrate that the effect of l-glutamine on PAP during pulmonary hypertension depends upon dose, time and the presence of endogenous NO synthesis. We believe that the results can be explained by two different effects of l-glutamine, namely a direct inhibition of NO release by glutamine and the donation of nitrogen atoms by glutamine for additional NO or other vasodilator synthesis. Since plasma glutamine levels are 0.4-0.7 mM, endogenous l-glutamine may play a modulatory role during pulmonary hypertension.

Animals↗
PubMed1994

Interleukin-1 upregulates decorin production by arterial smooth muscle cells.

An increase in dermatan sulfate-proteoglycan (DSPG) production occurs in cultured aortic smooth muscle cells exposed to macrophage-conditioned media, an effect that is abrogated by an antibody to interleukin-1 (IL-1). To determine which DSPG gene was regulated, cultured arterial smooth muscle cells from monkeys (Macaca fascicularis) were treated with 0 to 500 pg/mL human recombinant IL-1 alpha or IL-1 beta in the presence of [35S]sulfate and [3H]serine. Proteoglycans were isolated from the culture media and purified by selective precipitation and chromatography. Both recombinant IL-1 alpha and IL-1 beta caused a dose-response increase in DSPG production. Northern blot analysis of mRNA isolated from the cells identified 1.6-kb and 2.6-kb transcripts homologous to the cDNA encoding human decorin and biglycan, respectively. IL-1 treatment resulted in increases in the steady-state level of decorin mRNA as high as fourfold to sixfold at 500 pg/mL recombinant IL-beta. By contrast, mRNA for biglycan was unchanged. Western blotting confirmed a specific enhancement of the 45-kD decorin core protein. These data indicate that IL-1 has differential effects on the two DSPG genes and suggest that macrophages may be capable of modifying the extracellular matrix of the artery wall by enhancing smooth muscle cell decorin production.

Animals↗
PubMed1994

Determinants of basal follicle-stimulating hormone levels in premenopausal women.

The (basal) level of FSH measured during early menses is emerging as a predictor of ovarian competence. In this study, correlates of basal FSH were examined in 222 premenopausal women who were not using oral contraceptives and selected from either the general population or a clinic for women with family histories of ovarian cancer. Using analysis of variance, the effect on FSH by age, smoking history, and reproductive variables was examined. Dietary galactose (as a potential oocyte toxin) was estimated, and red cell activity of galactose-1-phosphate uridyl transferase (GALT) was measured. Qualitative features of GALT were described by its electrophoretic or molecular genetic patterns. Possession of GALT polymorphisms previously linked with low GALT activity, including the Q188R mutation of classic galactosemia or N314D mutation of the Duarte galactosemia variant, was associated with significantly higher FSH, even in the heterozygous state. Other factors significantly influencing FSH included age, smoking history, cycle length, and cycle regularity. No effect of current galactose consumption was found, and GALT activity was only weakly correlated (inversely) with FSH. Applying multiple linear regression, variables independently predictive of high FSH were age of 40 yr or more, current smoking, and possession of a GALT polymorphism.

Adult↗
PubMed1994

Antitumor activity of immunoconjugates composed of boanmycin and monoclonal antibody.

Boanmycin (bleomycin A6, BM), an antitumor antibiotic, was conjugated to monoclonal antibodies including R19, H111 and CCT2. The immunoconjugates exhibited selective cytotoxicity to related target cells including cecum cancer Hce-8693 cells, liver cancer BEL-7402 cells and leukemia CEM cells. They were highly effective against related human tumor xenografts in nude mice, and the inhibition rates by the conjugates were much higher than those by free BM. The inhibition rate by R19-BM conjugate against human cecum cancer xenografts reached 90%. BY immunoelectron microscopy, CCT2-BM conjugate showed specific binding and internalization in leukemia CEM cells. The results indicate that boanmycin-monoclonal antibody immunoconjugates are highly active both in vitro and in vivo.

Adenocarcinoma↗
PubMed1994

[Establishment of mouse model for Cysticercosis cellulosae].

Sixty mice were inoculated intravenously with 200-400 Taenia solium eggs collected from the gravid proglottides of the adult worm expelled from a taeniasis patient after pumpkin seed and areca treatment. The mice were killed and dissected 2 months after inoculation, and were found infected with Cysticercus cellulosae. These living cysticerci in muscles and lungs were elliptic in shape with diameters of 0.3-0.6 cm. The scolex was equipped with two rows of hooks and four typical suckers. When the cysticerci were hatched in gastric juice and bile for two hours at 37 degrees C the scoleces evaginated voluntarily. The results of this study suggest that the mouse can be used as an animal model for Cysticercus cellulosae.

Animals↗
PubMed1994

[The effect of Baji Zibugao on the serum levels of endocrines in thyroidectomized (yang deficiency) rabbits].

In order to study the effect of Baji Zibugao (BJZBG, a medicinal plaster mainly consisting of Radix Morindae Officinalis) on the endocrine functions of hypothyroid rabbits, we determined the serum levels of thyroxine (T4), triiodothyronine (T3), cAMP, cGMP and corticosterone in three groups of rabbits: total thyroidectomized and untreated (group I), total thyroidectomized and treated with BJZBG (group II) and controls (group III). The results showed: (1) The serum level of T4 in group I and II after operation was significantly lower than that before operation (P < 0.005), and the serum level of T3 in group I was also lower than that before operation (P < 0.02), but the change of T3 in group II after operation was not significant (P > 0.05); (2) The serum cAMP level in group I after operation decreased and the cGMP level increased (P < 0.025), but the changes of cAMP and cGMP level in group II after operation were not significant (P > 0.05), (3) The change of serum corticosterone level in group I or II after operation was not remarkable (P > 0.05).

Animals↗
PubMed1994

[Prognostic value of blink reflex in patients with Bell's palsy].

Blink reflex(BR) and electroneurography (ENoG) were carried out in 31 healthy people to obtain normal value. The manifestations of nerve excitability test(NET), ENoG and BR of 60 patients with Bell's palsy within 3 weeks of onset were studied. The results indicated that when the appearance of BR was regarded as good prognosis, facial paralysis recovered completely, the rate of accuracy of predicting facial paralysis was 100%, when the disappearance of BR was regarded as bad prognosis, it isn't a useful test for evaluating prognosis of facial paralysis within the first week of onset (for very few cases tested with NET and ENoG), and less useful than ENoG and NET within the second week and similar to ENoG and NET within the third week of onset.

Adolescent↗
PubMed1994

[The effect of wheat germ agglutinin on anion transport in the erythrocyte membranes].

The wheat germ agglutinin (WGA) has been recognized as the lectin that can agglutinate human erythrocytes. It is reported recently that the binding of WGA to the glycophorin blocks the morphological conversions of discocyte<-->echinocyte. Glycophorin is thought to be associated with Band 3, the anion transport protein, via the cytoskeleton proteins Band 4.1, spectrin and ankyrin. The effect of WGA on the anion transport across the erythrocyte membranes was measured by NO2- transport and NH4 Cl isotonic swelling, two different methods developed by our laboratory in recent years. The results showed that the rate of anion transport was decreased, depending on WGA concentration. This effect became saturated when WGA concentration reached 2-3 micrograms/ml. We have also observed that in certain conditions when the morphological conversion of discocyte-->elliptocyte was induced by high concentration of WGA, the rate of anion transport could be reversely increased. Furthermore, the effect of WGA on erythrocyte osmotic fragility was studied. The results indicated that the osmotic fragility was reduced after adding WGA to the erythrocyte suspension, which means the erythrocyte cytoskeleton is more stable under this condition. All effects that WGA exerted above were instantly abolished by adding N-acetylglucosamine which has specific binding sites on WGA. In conclusion, the binding of WGA to the sialic acid groups of glycophorin can lead to the conformational changes in saccharides and such changes will be transferred via glycophorin, cytoskeleton to Band 3, which causes the final change of anion transport. The effect is indirect, so the change is small (approximately 10%).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylglucosamine↗
PubMed1994

Transmembrane Ca2+ gradient-mediated change of fluidity in the inner layer of phospholipids modulates Ca(2+)-ATPase of sarcoplasmic reticulum.

Sarcoplasmic reticulum (SR) vesicles with (1000 folds) or without transmembrane Ca2+ gradient have been prepared. Different fluorescence probes (DPH, TMA-DPH and n-AS), were used to determine the effect of transmembrane Ca2+ gradient on the lipid fluidity both in outer and inner layer of Ca(2+)-ATPase-containing SR vesicles. The results showed that transmembrane Ca2+ gradient could significantly decrease the fluidity of the inner layer of SR membrane, while no obvious change was monitored in the outer layer. This may be deduced that Ca(2+)-ATPase might be modulated mainly by the transmembrane Ca2+ gradient-mediated alteration of physical state of phospholipid in the inner layer of SR membrane.

Animals↗
PubMed1994

[Compounds from Caesalpinia sappan L].

Two compounds were isolated from the stem of Caesalpinia sappan. Their structures were elucidated on the basis of physical and spectral analysis. They were named as tetraacetylbrazilin and protosappanin A respectively.

Benzopyrans↗
PubMed1994

Effect of cholinesterase inhibition in vitro by huperzine analogs.

Huperzine (Hup) A and B were first discovered and studied by Chinese. Fourteen analogs of Hup were tested for their anticholinesterase (anti-ChE) activity by colorimetric method using rat erythrocyte membrane and serum as enzyme sources. Hup-A showed the highest anti-AChE potency. The anti-BuChE activity of (-)dihydro and (-)tetrahydro analogs were potent than those of Hup-A. Their anti-AChE activities were comparable to those of physostigmine and galanthamine. Dihydro analog inhibition was of the mixed competitive type with a Ki value of 0.12 mumol.L-1. Tetrahydro analog inhibition was of the competitive type with a Ki value of 0.56 mumol.L-1. They were different from isoflurophate to bond to AChE in a reversible manner.

Acetylcholinesterase↗