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Biomedical subjects

C Hou

Publications and source records attributed to C Hou.

At least 91 records · Page 5Linked to original sources
PubMed1995

[An experimental study on changes in collagen content after homologous cartilage implantation].

This experiment studied the changes in cartilage collagen content during 1-20 weeks after allografting of cartilage. The results showed that the collagen content was reduced beginning from the 3rd week, and reached the lowest point in the 4th week (P < 0.05). Then it rose continuously and attained the normal level in the 8th week (P > 0.05). The study suggests that the changes in cartilage collagen content may help us to assess the cartilage structure and the elasticity after a cartilage allotransplantation.

Animals↗
PubMed1995

[In vitro experiment on scavenging oxy-radical and suppressing myocardial lipid peroxidation with sini decoction].

Results indicate that Sini Decoction has a significant effect of anti-lipid peroxidation of its components, Radix Aconiti Preparata and Radix Glycyrrhizae can significantly suppress lipid peroxidation of myocardial homogenate, while Rhizoma Zingiberis cannot. The decoction can effectively scavenge oxygen free radicals, each component having similar effect to some extent.

Animals↗
PubMed1994

Subtype-specific signaling mechanisms of somatostatin receptors SSTR1 and SSTR2.

Somatostatin regulates diverse cellular effectors, including adenylyl cyclase, ion channels, and ion exchangers. We expressed two somatostatin receptor subtypes, SSTR1 and SSTR2, stably in mouse fibroblast Ltk- cells and transiently in human embryonic kidney HEK293 cells to investigate subtype-specific pharmacological and functional properties. The effects of GTP gamma S and pertussis toxin on [125I-Tyr11]somatostatin-14 binding indicated that SSTR2 may couple exclusively to pertussis toxin-sensitive G proteins, whereas SSTR1 may couple to both pertussis-sensitive and -insensitive G proteins. When expressed either stably or transiently, both receptor subtypes mediated somatostatin inhibition of cAMP accumulation by a pertussis toxin-sensitive mechanism. In contrast, only SSTR1 mediated somatostatin inhibition of Na(+)-H+ exchange activity, and this action was insensitive to pertussis toxin. We generated two chimeric receptors by replacing sequential residues of SSTR2 with cognate sequences of SSTR1 to identify molecular determinants unique to SSTR1 that may confer coupling to the exchanger. SSTCR4 included a SSTR1 segment encompassing determinants within the fifth and sixth hydrophobic domains and the entire third cytoplasmic loop, while SSTCR5 contained a SSTR1 segment spanning the second through sixth hydrophobic domains, including both second and third cytoplasmic loops. Although both chimeric receptors mediated somatostatin inhibition of cAMP accumulation, only SSTCR5 mediated the inhibition of Na(+)-H+ exchange activity, and this effect was pertussis-insensitive. These findings demonstrate both pharmacological and functional differences between SSTR1 and SSTR2. The ability of SSTR1 to selectively attenuate Na(+)-H+ exchange activity requires determinants outside the third cytoplasmic domain.

Adenylate Cyclase Toxin↗
PubMed1994

Family affiliation and prostitution in a cultural context: career onsets of Taiwanese prostitutes.

American researchers emphasize family disaffiliation resulting from negative experiences as an important career contingency for prostitutes. They suggest that cohesive families insulate daughters from entering prostitution, an implication that ignores cultural variations within the United States and worldwide. This study examined the nature of family affiliations among prostitutes in Taiwan, a nation characterized by strong family cohesion and widespread prostitution. The traditional status and role of daughters in Taiwanese families is described. A sample of 89 prostitutes were interviewed in Taipei. The majority had good or very good relationships with their parents before the women left home and continued to maintain such relationships. Only 10% mentioned negative family experiences as precipitating factors in the decision to enter prostitution. A typology of career onsets was drafted. About one third of the sample entered the occupation out of a sense of filial obligation toward their families of origin. Other precipitating factors included paying off their own or husbands' debts, upgrading their financial status, deriving other satisfactions from the life-style, escaping from difficulties with parents or husbands, and being victimized by force or fraud. Several social changes are likely to lessen the importance of filial obligation as a career contingency of prostitution. Speculations about the future of Taiwanese prostitution are offered.

Adolescent↗
PubMed1994

[Mechanisms responsible for protective effect of Sini decoction on ischemic myocardium in mice].

The possible mechanisms responsible for the protective effect of Sini decoction (SND) on the ischemic myocardium were studied on the mice model of pituitrin-induced myocardial ischemia in terms of free radical. Results indicated that SND significantly decreased the concentration of oxygen free radical and the content of malondialdehyde (MDA), increased nutritional blood flow and the activity of superoxide dismutase (SOD) in ischemic myocardium. These results suggested that three mechanisms whereby SND exerted its protective effects existed; improving the perfusion of ischemic myocardium, attenuating the injurious action of free radical and strengthening the free radical defense.

Animals↗
PubMed1994

[A study of method of repair of defects of nasal tip and ala].

Since 1957, the authors repaired 119 cases of nasal tip and alar defects using four kinds of method: (1) 27 cases by full-thickness skin graft; (2) 36 cases by free auricular composite graft; (3) 12 cases by local skin flap; (4) 44 cases by upper arm tube flap. The operation method was selected according to the size of nasal defect, available quantity of the remnant nasal tip and ala, and the soft tissue around the defect. The following problems were discussed in detail: (1) the principles of the selection of repairing method; (2) operative procedure; (3) the key points for the repair of nasal defects.

Burns↗
PubMed1994

[Reconstruction of eyebrows by superficial temporal artery island flap (clinical analysis of 34 cases)].

The authors used the superficial temporal artery island flap in 34 cases for the reconstruction of the defective eyebrows and obtained good results. The present article introduces the operation technic and the following problems were discussed in detail: how to keep the grafted island flap survive; how to maintain the configuration of the reconstructed eyebrows; the principles of the operation designs.

Adolescent↗
PubMed1992

Stimulation of phospholipase C by guanine-nucleotide-binding protein beta gamma subunits.

We have previously shown that soluble fractions obtained from human HL-60 granulocytes contain a phospholipase C which is markedly stimulated by the stable GTP analogue guanosine 5'-[3-O-thio]triphosphate (Camps, M., Hou, C., Jakobs, K. H. and Gierschik, P. (1990) Biochem. J. 271, 743-748]. To investigate whether this stimulation was due to a soluble alpha subunit of a heterotrimeric guanine-nucleotide-binding protein or a soluble low-molecular-mass GTP-binding protein, we have examined the effect of purified guanine-nucleotide-binding protein beta gamma dimers on the phospholipase-C-mediated formation of inositol phosphates by HL-60 cytosol. We found that beta gamma subunits, purified from bovine retinal transducin (beta gamma t), markedly stimulated the hydrolysis of phosphatidylinositol 4,5-bisphosphate by this phospholipase C preparation. The stimulation of phospholipase C by beta gamma t was not secondary to a phospholipase-A2-mediated generation of arachidonic acid, was prevented by the GDP-liganded transducin alpha subunit and was additive to activation of phospholipase C by guanosine 5'-[3-O-thio]triphosphate. Beta gamma t also stimulated soluble phospholipase C from human and bovine peripheral neutrophils, as well as membrane-bound, detergent-solubilized phospholipase C from HL-60 cells. Stimulation of soluble HL-60 phospholipase C was not restricted to beta gamma t, but was also observed with highly purified beta gamma subunits from bovine brain. Fractionation of HL-60 cytosol by anion-exchange chromatography revealed the existence of at least two distinct forms of phospholipase C in HL-60 granulocytes. Only one of these forms was sensitive to stimulation by beta gamma t, demonstrating that stimulation of phospholipase C by beta gamma subunits is isozyme specific. Taken together, our results suggest that guanine-nucleotide-binding protein beta gamma subunits may play an important and active role in mediating the stimulation of phospholipase C by heterotrimeric guanine-nucleotide-binding proteins.

Animals↗
PubMed1992

Anomalous effect of uncouplers on respiratory chain-linked transhydrogenation in Escherichia coli membranes: evidence for a localized proton pathway?

Energization of the pyridine nucleotide transhydrogenase in everted membrane vesicles from Escherichia coli JM83 was compared with the process in vesicles of the same strain transformed with the plasmid pDC21 overexpressing this enzyme. Proton translocation was assayed by the quenching of the fluorescence of the probe quinacrine. Agents able to discharge transmembrane proton gradients such as nigericin and the uncouplers 3,3',4',5-tetrachlorosalicylanilide and carbonyl cyanide m-chlorophenylhydrazone inhibited ATP-dependent transhydrogenation of NADP by NADH and discharged transmembrane proton gradients generated by transhydrogenation of AcNAD by NADPH, by oxidation of NADH, and by hydrolysis of ATP. This was observed in everted membrane vesicles of both strains JM83 and JM83pDC21. These strains differed significantly in the response of the NADH oxidation-dependent transhydrogenase. This reaction was inhibited by nigericin and uncouplers in membrane vesicles of JM83 but there was little inhibition or the reaction was stimulated in JM83pDC21, in spite of the discharge of the NADH oxidation-generated proton gradient measured by quinacrine fluorescence in the latter strain. It is proposed that the transhydrogenase is energized by direct or local (nonbulk phase) proton translocation in membranes of this strain. Uncouplers might facilitate these routes but would not discharge them. The generality of these observations was shown using other strains. NADH oxidase activity was severalfold lower in membrane vesicles of JM83pDC21 compared with JM83. The levels of ubiquinone and cytochromes, and the activities of NADH dehydrogenases I and II, and of cytochrome oxidase, were similar in the two strains. It is concluded that the NADH oxidase activity of JM83pDC21 is low because of the reduced rate of collision between electron-transferring complexes of the respiratory chain due to the large amount of transhydrogenase protein in the membranes of this strain. The large amount of transhydrogenase favors direct, nonbulk phase proton transfer. Transhydrogenase activity was stimulated by Ca2+, Mg2+, or Mn2+.

Cell Membrane↗
PubMed1991

A preliminary report on the intervention trials of primary liver cancer in high-risk populations with nutritional supplementation of selenium in China.

The purpose of this study was to evaluate the effect of selenium (Se) in the prevention of human primary liver cancer. Three intervention trials were conducted among the residents at high risk to primary liver cancer (PLC) in Qidong county, Jiang-su province, the People's Republic of China. This area has the second highest rate of PLC in China. One trial was undertaken among the general population in a township with supplement of table salt fortified with 15 ppm anhydrous sodium selenite (Se-salt) for 5 y and the other four townships with similar PLC incidence rate served as the controls using normal table salt. The second trial was undertaken among hepatitis B virus surface antigen carriers (HBVsAg+) receiving supplement of 200 micrograms Se in form of selenized yeast (Se-yeast) daily vs placebo for 4 y. The third trial was carried out in members of families with high PLC incidence using Se-yeast (200 micrograms of Se daily) vs placebo for 2 y. The results showed that nutritional supplement of Se could reduce the PLC incidence significantly.

Adult↗
PubMed1990

Crosslinking and radiation inactivation analysis of the subunit structure of the pyridine nucleotide transhydrogenase of Escherichia coli.

The pyridine nucleotide transhydrogenase of Escherichia coli consists of two types of subunit (alpha: Mr 53,906; beta: Mr 48,667). The purified and membrane-bound enzymes were crosslinked with a series of bifunctional crosslinking agents and by catalyzing the formation of inter-chain disulfides in the presence of cupric 1,10-phenanthrolinate. Crosslinked dimers alpha 2, alpha beta and beta 2, and the trimer alpha 2 beta were obtained. A small amount of tetramer, probably alpha 2 beta 2, was also formed. Radiation inactivation was used to determine the molecular size of the transhydrogenase. The radiation inactivation size (217,000) and chemical crosslinking are consistent with the structure (Mr 205,146) being the oligomer that is responsible for biological activity.

Cobalt Radioisotopes↗
PubMed1990

Reaction of membrane-bound F1-adenosine triphosphatase of Escherichia coli with chemical ligands and the asymmetry of beta subunits.

The three beta subunits of the isolated Escherichia coli F1-ATPase react independently with chemical reagents (Stan-Lotter, H. and Bragg, P.D. (1986) Arch. Biochem. Biophys. 284, 116-120). Thus, one beta subunit is readily cross-linked to the epsilon subunit, Another reacts with N,N'-dicyclohexylcarbodiimide (DCCD), and the third one is modified on a lysine residue by 4-chloro-7-nitrobenzofurazan (NbfCl). The binding site for the ATP analog, 2-azido-ATP, was not associated with a specific type of beta subunit (Bragg, P.D. and Hou, C. (1989) Biochim. Biophys. Acta 974, 24-29). We now show that this binding site is a catalytic site as opposed to a noncatalytic nucleotide-binding site. NbfCl reacted with a tyrosine residue on the DCCD-reacting beta subunit in contrast to the different subunit location of the lysine residue labeled by the reagent. Thus, O to N transfer of the Nbf group in the free F1-ATPase involves transfer between subunits. The chemical labelling pattern of membrane-bound F1-ATPase differed from that of free F1. The strict asymmetry of labeling of the free F1-ATPase was not observed. Thus, double labeling of beta subunits by several reagents was found. This suggests that the asymmetry was not induced by chemical modification, but is inherent in the structure of the ATPase.

4-Chloro-7-nitrobenzofurazan↗
PubMed1990

Role of minor subunits in the structural asymmetry of the Escherichia coli F1-ATPase.

The beta subunits of the Escherichia coli F1-ATPase react independently with chemical reagents (Stan-Lotter, H. and Bragg, P.D. (1986) Arch. Biochem. Biophys. 248, 116-120). Thus, one beta subunit is readily crosslinked to the epsilon subunit, another reacts with N-N'-dicyclohexylcarbodiimide (DCCD), and a third one is modified by 4-chloro-7-nitrobenzofurazan (NbfCl). This asymmetric behaviour is not due to the association of the delta and epsilon subunits of the ATPase molecule with specific beta subunits since it is maintained in a delta, epsilon-deficient form of the enzyme.

Benzofurans↗
PubMed1989

Reaction of 2-azido-ATP with beta subunits in the F1-adenosine triphosphatase of Escherichia coli.

The three beta subunits of the Escherichia coli F1-ATPase react independently with chemical reagents (Stan Lotter, H. and Bragg, P.D. (1986) Arch. Biochem. Biophys. 248, 116-120). Thus, one beta subunit is readily cross-linked to the epsilon subunit, another reacts with N,N'-dicyclohexylcarbodiimide (DCCD), and the third one is modified by 4-chloro-7-nitrobenzofurazan (NbfCl). The relationship of the binding site for 2-azido-ATP to the three types of beta subunit recognized by chemical labeling was examined. The binding site for 2-azido-ATP was not associated with a specific type of beta-subunit. There was no relationship between the site of nucleotide and the association of the epsilon subunit with a particular beta subunit. It is concluded that the presence of the epsilon subunit (possibly in association with the other minor subunits) does not determine the position of the catalytic site. The possibility that the lack of a specific relationship between the 2-azido-ATP binding site and a specific beta subunit was due to turnover of the enzyme, making each beta a catalytic site in turn, could not be entirely rejected. However, the rate of hydrolysis of 2-azido-ATP by the DCCD-modified ATPase was very low in the presence of EDTA, and was likely due to catalysis at single sites.

Adenosine Triphosphate↗