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Biomedical subjects

G Hu

Publications and source records attributed to G Hu.

At least 199 records · Page 11Linked to original sources
PubMed1992

Effects of l-stepholidine on synaptosomal Ca(2+)-ATPase and subcellular calmodulin in rat striatum.

Our results showed that l-stepholidine (l-SPD) inhibited basal Ca(2+)-ATPase activity in rat striatal synaptosomes with an IC50 of 31.5 mumol.L-1, suggesting its interaction with Ca2+ transport. l-SPD inhibited also calmodulin (CaM)-activated basal Ca(2+)-ATPase in a concentration-dependent manner. A complete reversal of CaM activation of Ca(2+)-ATPase was observed with l-SPD 10 mumol.L-1. The activity of synaptosomal Ca(2+)-ATPase and membrane-bound CaM level were decreased in haloperidol (1 mg.kg-1.d-1, ip) and l-SPD (5, 10, and 30 mg.kg-1.d-1, ip) treated rats for 7 and 14 d, respectively. But the activity of Ca(2+)-ATPase and membrane CaM level were increased after treatment with the same of doses haloperidol and l-SPD for 21 d. During the treatments with haloperidol and l-SPD cytosolic and nuclear CaM levels were not altered. These results suggest that l-SPD may modulate the release and synthesis of dopamine (DA) and the negative feedback regulation of presynaptic DA receptors by altering Ca2+ and CaM regulating processes in the central dopaminergic nervous system.

Animals↗
PubMed1992

A novel variant of human interferon alpha 1 gene.

A 520-base pair human IFN-alpha gene was isolated by PCR method twice from chromosome DNA of a Chinese (Han Nationality) fetal liver. The nucleotide sequences were determined. These two separately amplified DNA fragments shared the completely identical nucleotide sequence but possessed C and G at positions 410 and 541, respectively, which differ from those of IFN-alpha 1 and IFN-alpha D previously described. Therefore the deduced amino acid sequence would have an Ala at position 114 and a Val at position 158. At all other sites it has the same amino acids as those in IFN-alpha 1 and IFN-alpha D. We recommend that IFN-alpha D gene, IFN-alpha I gene and IFN-alpha I/158V gene found in our laboratory, be named IFN-alpha 1a gene, IFN-alpha 1b gene and IFN-alpha 1c gene.

Amino Acid Sequence↗
PubMed1992

Antagonism of l-stepholidine on D2 receptor-mediated inhibition of synaptosomal adenylate cyclase in rat corpus striatum.

In the presence of Sch 23390 0.1 mumol.L-1, dopamine (DA) inhibited the activity of synaptosomal adenylate cyclase (AC) isolated from rat striatum in a concentration-dependent manner with IC50 value of 2.2 mumol.L-1. The maximal inhibition corresponded to a 51% decrease of basal enzyme activity and was obtained at DA 100 mumol.L-1. The inhibitory effect of DA was reversed by selective D2 receptor antagonist spiperone 10 mumol.L-1. N-0437, a selective D2 DA receptor agonist also inhibited the activity of AC in the manner similar to that of DA. Both the inhibitions induced by DA and N-0437 were antagonized by l-stepholidine (l-SPD). However, in the presence of Sch 23390, l-SPD alone also inhibited the activity of AC by 29% and 33% at the concentrations of 10 and 100 mumol.L-1, respectively. The inhibition of l-SPD on AC activity was significantly antagonized by spiperone. In the presence of Sch 23390, both DA and N-0437 increased the activity of high affinity GTP phosphohydrolase in striatal synaptosomes. The increases of GTP phosphohydrolase activity stimulated by DA and N-0437 were completely reversed by l-SPD 100 mumol.L-1. These results suggest that l-SPD antagonizes or reverses the D2 receptor-mediated inhibition of AC activity through affecting the regulation of Gi (inhibitory guanine nucleotide-dependent protein) on D2 receptor-coupled AC and therefore affects the negative feedback of presynaptic DA receptors. Moreover, the inhibition of AC activity induced by l-SPD alone may provide a useful biochemical index for dual action of l-SPD.

Adenylyl Cyclases↗
PubMed1992

Altered conformation of the p53 protein in myeloid leukemia cells and mitogen-stimulated normal blood cells.

Expression of the normal p53 gene promotes cell differentiation, maturation and apoptosis. The mutant p53 gene, which does not function normally, is frequently expressed at elevated levels in tumor cells [for review see Lane, D.P. & Benchimol, S. (1990). Genes Dev., 4, 1-8]. We have analysed the expression of and mutational change in the p53 gene in the peripheral blood cells of 49 primary acute myeloid leukemia (AML) patients. The p53 protein levels were elevated in 37 patients (75%) when measured by immunoprecipitation with antibodies PAb1801 and PAb421, which recognize both normal and mutant forms of the protein. The p53 protein from 32 of these 37 patients was immunoprecipitated by PAb240, which recognizes a conformation of p53 protein associated with point mutations. However, point mutations were detected by single-stranded conformation polymorphism (SSCP) assay and direct sequencing in only three patients at codons 178, 245, 273 and 290. Growth stimulation of normal lymphocytes also generated p53 which was immunoprecipitable by PAb240. Thus, alteration of p53 conformation, rather than acquisition of point mutations, could be the mechanism underlying the increased proliferation of myeloid cells in most AML patients.

Acute Disease↗
PubMed1990

Preliminary study of quantification of regurgitant volume in mitral regurgitation by color Doppler echocardiography.

A method for quantification of regurgitant volume in mitral regurgitation (MR) was studied. 31 cases of MR were investigated with color Doppler. The reliability of measuring velocity by Doppler and the influence of pressure gradient on MR were assessed and confirmed by experimental device. The results suggested that the best method in quantification of the regurgitant volume was "calibrating method" (r = 0.99; P less than 0.01), the next to the best was "volume method" (r = 0.74; P less than 0.01), whereas the regurgitant volume evaluated by multiplication of area, velocity and time was far from the actual regurgitant volume (r = 0.47; P greater than 0.05). The velocity of blood flow measured by Doppler is closely correlated to results obtained from experiments (r = 0.69; P less than 0.05). We believe that the ratio of back flow area and average area of left atrium calculated by Helmcke's method reflects the severity of the disease to a certain degree, bu there are many problems unsolved, e.g. the determination of the velocity of blood flow by color Doppler is dependent on the degree of brightness of coloration; the brighter the color, the quicker the speed it represents, whereas the darker coloration speaks for slower speed.

Echocardiography, Doppler↗
PubMed1990

[Electron microscopic observation of the effects of Rhodiola kirilowii (Regel.) Maxim. in preventing damage of the rat viscera by a hypoxic high altitude environment].

This paper has shown that the pathologic damages done to rat's viscera due to hypoxic environment of altitude can be reduced significantly by oral administrations of Shengmaiyin, Danshen-Chuanxiong mixture and Rhodiola kirilowii. Shengmaiyin that maintains interior substances in the plate layer bodies proves more effective than Danshen-Chuanxiong mixture, while the latter excels in preventing capillary contraction, thus improving blood circulation. Rhodiola kirilowii has the effects of both Shengmaiyin and Danshen-Chuanxiong mixtures.

Altitude Sickness↗
PubMed1987

Estrogen influences dolichyl phosphate distribution among glycolipid pools in mouse uteri.

The steroid hormone 17 beta-estradiol dramatically induces uterine N-linked glycoprotein assembly [Dutt, A., Tang, J.-P., Welply, J. K., & Carson, D. D. (1986) Endocrinology (Baltimore) 118, 661-673]. To determine the role that dolichyl phosphate availability plays in this induction, we studied the effects of estrogen priming on the content of dolichyl phosphate and the distribution of dolichyl phosphate among various glycolipids in uteri. Dolichol-linked saccharides were metabolically labeled to equilibrium with either [3H]glucosamine or [3H]mannose and extracted from primary explants of uterine tissue. The amount of dolichol-linked saccharide was calculated from the specific radioactivity determined for the corresponding sugar nucleotides extracted from the tissues. The major dolichol-linked saccharides identified were mannosylphosphoryldolichol (MPD), oligosaccharylpyrophosphoryldolichol (OSL), and N,N'-diacetylchitobiosylpyrophosphoryldolichol (CBL). Estrogen increased the levels of MPD and OSL 4-fold; however, CBL levels did not change. After 3 days of treatment, the levels of these glycolipids were very similar to those in uteri from pregnant mice. Remarkably, MPD constituted 90-95% of dolichol-linked saccharides detected under all conditions. The tissue contents of total dolichyl phosphate and alkali-labile dolichyl phosphate, presumably MPD, were estimated by liquid chromatography. The levels of alkali-labile dolichyl phosphate determined in this way were in good agreement with the values estimated for MPD by metabolic labeling; moreover, alkali-labile dolichyl phosphate constituted 50-98% of the total dolichyl phosphate pool. The variations in MPD content depended upon the steroid hormone influence, most notably that of estrogen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

Resistance to trimethoprim and other antibiotics in shigellae isolated in the province of Ontario.

Antimicrobial susceptibility determinations for three commonly used and seven seldom used antibacterial drugs against 482 strains of shigellae isolated in Ontario during 1977 and 1978 were carried out. Resistance to the first-line treatment drugs, ampicillin and tetracycline, occurred in 20.5 and 39.2% of strains, respectively. The emergence of trimethoprim-sulfamethoxazole resistance was noted for the first time in 3.2% of the strains in 1978. All strains retained their susceptibility to gentamicin, nalidixic acid, and polymyxin but were variably susceptible to chloramphenicol, cephalexin, and rifampin.

Anti-Bacterial Agents↗