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Biomedical subjects

G Hu

Publications and source records attributed to G Hu.

At least 145 records · Page 8Linked to original sources
PubMed1997

Impact mass chemotherapy with praziquantel on schistosomiasis control in Fanhu village, People's Republic of China.

The paper describes the endemic situation of schistosomiasis japonica in Fanhu village, Poyang Lake region, China and the effect of the strategy of combining annual mass chemotherapy with health education on schistosomiasis control in the community. The results showed that the prevalence of infection with schistosome reduced form 26.0% in 1992 to 10.7% in 1994, the intensity of infection in residents decreased from 1.92 in 1992 to 0.55 in 1994 and the condition of hepatomegaly, splenomegaly and liver fibrosis also improved after chemotherapy in the individuals in the case prospective study. Moreover, the future strategies of schistosomiasis control in this area have been suggested according to the transmission of schistosomiasis in the lake region and the effect of anti-schistosomiasis control indifferent populations.

Adolescent↗
PubMed1996

Posttranscriptional aspects of the biosynthesis of type 1 collagen pro-alpha chains: the effects of posttranslational modifications on synthesis pauses during elongation of the pro alpha 1 (I) chain.

Early studies indicated that chain elongation pauses were prominent during the in vivo synthesis of type I procollagen chains, and it was postulated [Kirk et al., (1987): J Biol Chem 262:5540-5545.] that these might have a role in the coordination of procollagen I molecular assembly. To examine this postulate, polysomes isolated from [(14)C]-Pro-labeled 3T6 cells were subjected to SDS-PAGE. The resulting gels were Western blotted and screened with a monoclonal antibody (SP1 .D8) directed against the N-terminal region of the pro alpha 1 (I) chain. The blots were fluorographed, which also permitted analysis of the pro alpha 2 (I) chain. There was a prominent pro alpha1 synthesis pause near the completion of full-length chain elongation, not matched by a pro alpha 2 pause. The amount of labeled polysome-associated near-full length pro alpha 1 (I) chains increased in parallel with labeling time. After 24 h in culture -[(14)C-Pro], collagen synthesis ceased but unlabeled polysome-associated pro alpha1 chains were readily detected by SP1 .D8. Change to fresh culture medium +[(14)C-Pro] reinitiated synthesis and permitted tracing of the newly synthesized labeled pro a chains through the polysome and intracellular compartments. The secreted procollagen molecules had a 2:1 pro alpha 1 (1):pro alpha 2 (I) chain ratio but the polysome-bound peptides did not. Pulse-chase experiments showed that near-full length pro alpha 1 (I) chains remained bound to polysomes as long as 4 h after reinitiation of translation but there was no evidence for pro alpha 2 (I) chain accumulation. The hydroxylation inhibitor alpha, alpha'-dipyridyl, and triple-helix inhibitors cis-hydroxyproline and 3,4 dehydroproline had minimal effects on the buildup of polysome-associated pro al chains. The glycosylation inhibitor tunicamycin also failed to change the final pro alpha 1 chain pausing, but it did cause the appearance of several discrete lower molecular weight pro alpha 1-related polypeptides that could not be accounted for simply as the result of lack of N-linked glycosylation in the C-propeptide regions. Disulfide bond experiments showed that some of the paused nascent polysome-associated pro alpha 1 (I) chains were disulfide bonded. Thus, while synthesis of pro alpha 1 (I) and pro alpha 2 (I) chains proceeds in parallel within the same ER compartments, their elongation rates are not coordinated. Interactions leading to heterotrimer formation are a late event which may affect the rate of release of the completed pro alpha 1 (I) chain from the polysome. The release of completed nascent pro alpha 1 (I) chains from their polysomal complexes is regulated by a mechanism not operating in the synthesis of pro alpha 2 (I) chains. The pro alpha 1 (I) chain release process is not connected directly with hydroxylation, glycosylation or triple-helix formation.

Animals↗
PubMed1996

Dietary sodium and potassium, socioeconomic status and blood pressure in a Chinese population.

The average total intake of sodium was 6.11 g in a Chinese urban diet and 6.49 g in the rural sample in China. Discretionary use of salt provided 53% of the total sodium intake in the urban and 63% in the rural diet. Sodium intakes derived from processed foods, soy sauce and monosodium glutamate were 17%, 16% and 6% respectively in the urban diet, and 4%, 16%, 2% respectively in the rural diet. The mean intake of potassium was 1.95 g in the urban and 1.83 g in the rural diet. Cereals and vegetables were the major sources of dietary potassium. The intakes of total sodium, salt and soy sauce decreased as educational level increased. Similar results were found in white-collar workers and blue-collar workers or farmers. Nevertheless, an inverse association between blood pressure and education was found. The results suggest that reduction in sodium intake, especially cooking salt, and increased potassium intake are needed for nutritional control of hypertension in population-based interventions aimed at all social classes.

Adult↗
PubMed1996

Comparison of MSX-1 and MSX-2 suggests a molecular basis for functional redundancy.

This study examines the biochemical properties of two members of the murine MSX family, MSX-1 and MSX-2, which have been implicated to have partially overlapping functions during embryogenesis. Our analyses show that MSX-1 and MSX-2 share many features in common including their DNA binding and transcriptional properties. In particular, MSX-1 and MSX-2 interact with a common consensus DNA site, and exhibit similar DNA binding site preferences. However, MSX-2 has a higher apparent affinity for DNA, and the distinction between MSX-1 and MSX-2 resides in their differing sequences N-terminal to the homeodomain. With respect to their transcriptional properties, both MSX-1 and MSX-2 function as repressors and share the distinct property that they do so independently of their consensus DNA binding sites. However, MSX-1 is a more potent repressor, and the difference between these proteins also maps to their N-terminal regions. Similarly, the expression patterns of Msx-1 and Msx-2 as examined by whole mount in situ hybridization are related but not identical. Thus, Msx-1 and Msx-2 are co-expressed in the limbs, neural tube, and branchial arches; however, Msx-1 has a broader expression pattern overall and is expressed uniquely in certain embryonic regions. These features suggest that these members of the Msx family are 'equivalent but not equal' and that their proposed redundancy may be achieved via distinct biochemical mechanisms that yield a similar functional outcome.

Amino Acid Sequence↗
PubMed1996

Four-dimensional echocardiography: methods and clinical application.

4DE (i.e., dynamic three-dimensional) echocardiography is a new developing technique in recent years. In our study, a three-dimensional echo scan computer system was used to acquire and store the two-dimensional information, then to reconstruct the stereoscopic image of the heart according to its space-time continuum. It can yield a better approach, which can help identify the various structures of the heart and great arteries and facilitate understanding of spatial relations and motion. In addition, it can display physiologic information such as the direction, course, size, and shape of the blood flow. We have examined 138 patients by both transthoracic and transesophageal approaches. Our preliminary experience shows that 4DE is of great value in diagnosing congenital heart disease and valvular disease.

Adolescent↗
PubMed1996

[Protective effects of sodium selenite and selenomethionine on genotoxicity to human peripheral lymphocytes induced by arsenic].

Inhibition bioassay of sister chromatid exchanges (SCE) and DNA synthesis was carried out to study the mechanism that selenium, as a chemical agent for intervention, could antagonize the effects of arsenic on body damage and lower incidence of tumor. Results demonstrated that SCE frequency in peripheral lymphocytes induced by As2O3 could be significantly reduced by preincubation with 5 x 10(-7), 1 x 10(-6) mol/L Na2SeO3 and co-exposure of 1 x 10(-6) mol/L selenomethionine. Inhibition of DNA synthesis could be antagonized by preincubation in with 5 x 10(-6) mol/L Na2SeO3 and co-exposure of 1 x 10(-6), 5 x 10(-6) mol/L selenomethionine. But, the mechanism that protective effects of selenium on the damage to cell genetic material induced by arsenic should be studied further.

Antimutagenic Agents↗
PubMed1996

Signal transduction pathways in guinea pig sperm.

Trifluoperazine (TFP), the antagonist of calmodulin (CaM), significantly stimulated the capacitation and acrosome reaction of guinea pig spermatozoa at the concentration of 10-100 mumol/L, independent of the external Ca2+. Forskolin, dbcAMP and caffeine evidently promoted the occurrence of acrosome reaction of spermatozoa at early capacitation stage (5 h) in nonsynchronous system but not in synchronous system. If the spermatozoa were capacitated for 15 h in synchronous system, the above three drugs significantly stimulated acrosome reaction in a Ca(2+)-independent manner. Protein kinase C activators, i.e. phorbol 12-myristate 13-acetate (PMA) and phorbol 12,13-dibutyrate (PDB) did not influence the occurrence of acrosome reaction of spermatozoa at early capacitation stage, but significantly increased the acrosome reaction rate in capacitated spermatozoa in a Ca(2+)-independent manner. In contrast, PKC inhibitor staurosporine significantly inhibited the occurrence of acrosome reaction.

Acrosome↗
PubMed1995

Relationships between translation of pro alpha1(I) and pro alpha2(I) mRNAs during synthesis of the type I procollagen heterotrimer.

Final assembly of the procollagen I heterotrimeric molecule is initiated by interactions between the carboxyl propeptide domains of completed, or nearly completed nascent pro alpha chains. These interactions register the chains for triple helix folding. Prior to these events, however, the appropriate nascent chains must be brought within the same compartments of the endoplasmic reticulum (ER). We hypothesize that the co-localization of the synthesis of the nascent pro alpha1(I) and pro alpha2(I) chains results from an interaction between their translational complexes during chain synthesis. This has been investigated by studying the polyribosomal loading of the pro alpha-chain messages during in vitro translation in the presence and absence of microsomal membranes, and in cells which have the ability to synthesize the pro alpha1 homotrimer or the normal heterotrimer. Recombinant human pro alpha1(I) and pro alpha2(I) cDNAs were inserted into plasmids and then transcribed in vitro. The resulting RNAs were translated separately and in mixture in a cell-free rabbit reticulocyte lysate +/- canine pancreatic microsomes. Cycloheximide (100 mu g/ml) was added and the polysomes were collected and fractionated on a 15-50% sucrose gradient. The RNA was extracted from each fraction and the level of each chain message was determined by RT-PCR. Polysomes from K16 (heterotrimer-producing), W8 (pro alpha1(I) homotrimer), and A2' (heterotrimer + homotrimer) cells were similarly analyzed. Translations of the pro alpha1(I) and pro alpha2(I) messages proceeded independently in the cell-free, membrane-free systems, but were coordinately altered in the presence of membrane. The cell-free + membrane translation systems mimicked the behavior of the comparable cell polysome mRNA loading distributions. These data all suggest that there is an interaction between the pro alpha chain translational complexes at the ER membrane surface which temporally and spatially localize the nascent chains for efficient heteromeric selection and folding.

Animals↗
PubMed1995

Endoplasmic reticulum protein Hsp47 binds specifically to the N-terminal globular domain of the amino-propeptide of the procollagen I alpha 1 (I)-chain.

Hsp47, an endoplasmic reticulum-resident heat shock protein in fibroblasts, has gelatin-binding properties. It had been hypothesized that it functions as a chaperone regulating procollagen chain folding and/or assembly, but the mechanism of the hsp47-procollagen I interaction was not clear. Hsp47 could bind to both denatured and native procollagen I. A series of competition studies were carried out in which various collagens and collagen domain peptides were incubated with 35[S]-methionine-labeled murine 3T6 cell lysates prior to mixing with gelatin-Sepharose 4B beads. The gelatin-bound proteins were collected and analyzed by gel electrophoresis and autoradiography. Collagenase digested procollagen I had the same effect as denatured intact procollagen, indicating that the propeptides were the major interaction sites. The addition of intact pro alpha 1(I)-N-propeptide at 25 micrograms/ml completely inhibited hsp47 binding to the gelatin-Sepharose. Even the pentapeptide VPTDE, residues 86-90 of the pro alpha 1(I)-N-propeptide, inhibits hsp47-gelatin binding. These data implicating the pro alpha 1(I)-N-propeptide domain were confirmed by examination of polysome-associated pro alpha chains. The nascent pro alpha 1(I)-chains with intact N-propeptide regions could be precipitated by monoclonal hsp47 antibody 11D10, but could not be precipitated by monoclonal anti-pro alpha 1 (I)-N-propeptide antibody SP1.D8 unless dissociated from the hsp47. GST-fusion protein constructs of residues 23-108 (NP1), 23-151 (NP2), and 23-178 (NP3) within the pro alpha 1 (I)- N-propeptide were coupled to Sepharose 4B and used as affinity beads for collection of hsp47 from 3T6 cell lysates. NP1 and NP2 both showed strong specific binding for lysate hsp47. Finally, the interaction was studied in membrane-free in vitro cotranslation systems in which the complete pro alpha 1(I)- and pro alpha 2(I)-chain RNAs were translated alone and in mixtures with each other and with hsp47 RNA. There was no interaction evident between pro alpha 2(I)-chains and hsp47, whereas there was strong interaction between pro alpha 1(I)-chains and nascent hsp47. SP1.D8 could not precipitate pro alpha 1(I)-chains from the translation mix if nascent hsp47 was present. These data all suggest that if hsp47 has a "chaperone" role during procollagen chain processing and folding it performs this specific role via its preferential interaction with the pro alpha 1 (I) chain, and the pro alpha 1(I) amino-propeptide region in particular.

Amino Acid Sequence↗