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Biomedical subjects

T Zhu

Publications and source records attributed to T Zhu.

At least 91 records · Page 5Linked to original sources
PubMed1998

An African HIV-1 sequence from 1959 and implications for the origin of the epidemic.

There is considerable genetic diversity among viruses of different subtypes (designated A to J) in the major group of human immunodeficiency virus type 1 (HIV-1), the form of HIV that is dominant in the global epidemic. If available, HIV-1 sequences pre-dating the recognition of AIDS could be crucial in defining the time of origin and the subsequent evolution of these viruses in humans. The oldest known case of HIV-1 infection was reported to be that of a sailor from Manchester who died of an AIDS-like illness in 1959; however, the authenticity of this case has not been confirmed. Genetic analysis of sequences from clinical materials obtained from 1971 to 1976 from members of a Norwegian family infected earlier than 1971 showed that they carried viruses of the HIV-1 outlier group, a variant form that is mainly restricted to West Africa. Here we report the amplification and characterization of viral sequences from a 1959 African plasma sample that was previously found to be HIV-1 seropositive. Multiple phylogenetic analyses not only authenticate this case as the oldest known HIV-1 infection, but also place its viral sequence near the ancestral node of subtypes B and D in the major group, indicating that these HIV-1 subtypes, and perhaps all major-group viruses, may have evolved from a single introduction into the African population not long before 1959.

Democratic Republic of the Congo↗
PubMed1998

Clinical study on chronopharmacokinetics of digoxin in patients with congestive heart failure.

Fluorescence polarization immunoassay was used to study the chronopharmacokinetics of digoxin in 10 patients with congestive heart failure (CHF) who also served as self-controls. Our results showed that the serum digoxin concentration reached peak value 1 h after taking digoxin at 7:00 a.m., but the serum digoxin concentration reached the peak value 2 h after taking digoxin at 4:00 p.m. The average serum digoxin concentration area under curve was greater and the best maintainable time of serum concentration within 24 h after taking digoxin at 4 p.m. longer than those at 7:00 a.m. The heart rates were obviously lower and the cardiac function was significantly improved in 4:00 p.m. group.

Adult↗
PubMed1998

Perception of foreign cigarettes and their advertising in China: a study of college students from 12 universities.

OBJECTIVE: To examine how deeply foreign cigarette advertising had penetrated the Chinese market when a new ban on cigarette advertising was enacted in February 1995. DESIGN: A survey using self-completion questionnaires administered in college classrooms from November 1994 to March 1995. SETTINGS: Eight universities and four medical schools in three Chinese cities: Beijing, Wenzhou, and Hangzhou. SUBJECTS: 1896 college students who agreed to complete a written questionnaire. The mean age was 21.2 years; 39.5% of respondents were female. RESULTS: Four of the top eight cigarette brands most familiar to the respondents were foreign: Marlboro, 555, Kent, and Hilton. Advertisements for the foreign brands were much more likely to be seen than those for the domestic brands; those for Marlboro were reported most often (29.7%), followed by 555 (21.8%) and Kent (18.1%). Among smokers, Marlboro was the most preferred foreign brand, by 44.2%. The preference for Marlboro was also correlated with smokers having seen its advertisements. Most respondents, 71.8%, believed that cigarette advertising should be banned. CONCLUSIONS: The previous restrictions on cigarette advertising in China failed to prevent a large portion of the population from seeing and understanding the advertisements. Before the 1995 advertising ban took effect, strict limitations on imports of foreign cigarettes notwithstanding, certain highly advertised brands such as Marlboro achieved wide recognition and even consumer preference. Stricter restrictions are suggested as previous ones have failed to achieve their intended effects.

Adolescent↗
PubMed1998

[Effect of apolipoprotein E gene plasma levels of lipids, lipoproteins, apolipoproteins and its relation with coronary heart disease].

Using a technique of polymerase chain reaction-restriction lengths polymorphism (PCR-RLP), the authors detected the genotypes of apolipoprotein EE(ApoE) in 102 normal control subjects and in 118 patients with coronary heart disease (CHD). Meanwhile, the effect of ApoE allele on plasma lipid, lipoprotein, apolipoprotein levels were analyzed, and ApoE allele frequencies of patients with CHD and of control subjects were compared. The results showed that the technique of modified PCR-RFLP was a useful measure to detect the genotypes of ApoE. ApoE gene was polymorphism, resulting in plasma lipid level variance among individuals. As compared to ApoE3 allele, ApoE4 allele had positive effect on plasma TC, LDL-C and ApoB100 levels; while ApoE2 allele had negative effect on plasma TC, LDL-C and ApoB100 levels. The frequency of E4 allele in patients with CHD was higher than that in control subjects. The results in the present study suggest that ApoE4 allele is probably the genetic marker of CHD.

Aged↗
PubMed1998

Expression of type-I collagen and matrix metalloproteinase-9 mRNA in bone of castrated adult female rats: effects of estrogen.

OBJECTIVES: To elucidate the molecular changes of bone collagen during the development of postmenopausal osteoporosis and to investigate the molecular effects of estrogen replacement. METHODS: An adult ovariotomy rat model was used. Type-I collagen and matrix metalloproteinase-9 (MMP-9) expressions in bone tissues of rats treated by sham surgery (SH), bilateral ovariotomy (OVX) and OVX with estradiol (OVX-E2) were analysed at mRNA level by using dot blot technique. The distribution of mRNA of these two genes in bone tissues was studied by in situ hybridization. RESULTS: The expression levels of both type-I collagen and MMP-9 in bone tissues of OVX rats were higher than those of SH group, while treated with estradiol, the expression of both genes declined to some degree. In situ hybridization showed that type-I collagen mRNA located in osteoblasts, whereas MMP-9 was mainly expressed in osteoclasts, some lining cells on bone surface, and some mononuclear cells in bone marrow. CONCLUSIONS: The reduction of high bone turnover in osteoporotic bone tissues induced by estrogen replacement may result from alterations in gene expression related to bone formation and bone resorption. These alterations are consistent with the changes observed previously by histomorphometry and biochemical markers of bone metabolism on OVX animals and postmenopausal osteoporosis.

Animals↗
PubMed1997

The interconversion of protein phosphatase 2A between PP2A1 and PP2A0 during retinoic acid-induced granulocytic differentiation and a modification on the catalytic subunit in S phase of HL-60 cells.

Alterations in protein phosphatase 2A (PP2A) during retinoic acid-induced differentiation of HL-60 cells have been investigated. PP2A activity of HL-60 cells for phosphorylated myelin basic protein showed a sharp and transient increase after 18-h treatment with 1 microM retinoic acid, which corresponded to G1/S boundary of the cell cycle. This PP2A of the 18-h treated cells was eluted from a DEAE-Sepharose column with 0.13 M NaCl, while PP2A from control cells was eluted with 0.23 M NaCl. The phosphorylase phosphatase activity of PP2A in the 0.13 M eluate was greatly enhanced in the presence of protamine compared with that of the later eluting PP2A. Immunoblot analyses with antisera against B' and B alpha subunits showed that the PP2A in the 0.13 M NaCl eluate from 18-h retinoic acid-treated cells was PP2A0 (AC-B'), whereas the PP2A eluted with 0.23 M NaCl from 24-h retinoic acid-treated cells and 0-, 18-, and 24-h control cells was PP2A1 (AC-B alpha). These results strongly suggest that PP2A undergoes a transient and reversible interconversion of holoenzyme forms during the initial stage of retinoic acid-induced granulocytic differentiation. PP2A activity assayed after dissociation of the catalytic subunit, for phosphorylase as substrate, showed a sharp and transient decrease in S phase of HL-60 cells irrespective of the presence or absence of retinoic acid. Immunoblot analyses with antisera against C-terminus and N-terminus of the catalytic subunit of PP2A suggested that a modification at the C-terminus is responsible for the decrease in PP2A activity. Immunoreactivity to the C-terminal antibody was restored after treatments of the S-phase extract with alkali or ethanol, the conditions which remove the methyl group from the C-terminus. These results suggest that the C-terminus of PP2A catalytic subunit is transiently methylated in S phase of HL-60 cells.

Blotting, Western↗
PubMed1997

Expression of matrix metalloproteinase-9 mRNA in osteoporotic bone tissues.

Matrix metalloproteinases (MMPs), a sort of important enzymes involved in extracellular matrix metabolism, play critical roles in the process of tissues remodeling, wound healing and metastasis of tumors. Dot blot and in situ hybridization were used in this study to detect the expression and localization of MMP-9, an important proteolytic enzyme implicated in bone resorption in bone tissues. The results showed that the level of MMP-9 mRNA expression in osteoporotic bone tissues was significantly higher than that in normal control group and the cell types that expressed MMP-9 mRNA included mono- and multi-nuclear osteoclasts and some lining cells on the surface of bone matrix. It was suggested that MMP-9 play a key role in the development of bone loss in osteoporosis.

Animals↗
PubMed1997

Tissue response and the cytoconduction ability to collagen/hydroxyapatite heterotopic implantation.

A histological and ultrastructural observation of CHA implanted intramuscularly and subcutaneously had been reported. Our results showed that a mild inflammation developed at the early stage and disappeared 2 weeks after implantation. The infiltrating cells were mainly monocyte-macrophages, a number of fibroblasts followed macrophages closely. It was possible that as CHA degrades, monocyte-macrophages continuously released inflammatory factors, thus enhancing fibroblast proliferation activity and tissue regeneration. In addition, the heterotopic calcification of collagen matrix was observed, suggesting that CHA promoted calcification deposition.

Animals↗
PubMed1997

The STR120 satellite DNA of soybean: organization, evolution and chromosomal specificity.

A highly repeated DNA sequence family, STR120, with tandemly arranged repetitive units (monomers) of approximately 120bp, has been identified in soybean [Glycine max (L.) Merr.]. Five related clones showing tandem repeats of a 120-bp-long monomer were isolated from a soybean genomic library. Results of Southern blotting experiments using three of the clones as probes onto genomic DNA digested with different restriction enzymes were in agreement with a tandem arrangement of these sequences in the genome. A total of 12 monomers were sequenced, showing considerable sequence heterogeneity. A consensus sequence of 126 bp was obtained that exhibits an average similarity of 81% to the sequenced units. In three of the clones identified, neighbouring units are significantly more similar to each other than to units from different clones; in the remaining two clones, however, similarity between the two units observed is low (70%), while the overall similarity between the two clones is high (95%). This indicates that in these cases the repetitive unit may be the dimer rather than the monomer. Based on the presence of direct repeats within each monomer, we suggest that the 120-bp monomer may itself have evolved by duplication of an ancestral 60-bp unit. The STR120 family distribution is limited to annual soybeans and is not found, at least at high-copy number, in related perennial soybeans or other members of the tribe Phaseolae. Fluorescence in situ hybridization (FISH) to metaphase chromosomes using four of the clones as probes shows that the number of chromosomal locations differs depending on the stringency conditions and goes from two to eight when the stringency is progressively lowered. The estimated copy number for one of the clones is from 5000 to 10000, but this may just represent a lower boundary for the whole family in consideration of the high sequence divergence observed within the family. FISH and sequence analysis therefore indicate that different subfamilies as well as higher-order repeat units are present in the STR120 family, very much like those in primate alpha satellite DNA, and that some of the subfamilies seem to exhibit divergence on a chromosomal basis.

Base Sequence↗
PubMed1997

[Colour Doppler ultrasonographic indices in predicting fetal hypoxia and acidosis].

OBJECTIVE: To evaluate the effect of uterine-placental-fetal blood flow velocity waveforms (FVWs) on predicting fetal hypoxia and acidosis in high risk pregnancy. METHODS: 46 women of normal term pregnancy (normal group) and 32 women of high risk term pregnancy (high risk group) were examined with colour Doppler ultrasound for their FVWs including maternal uterine artery (UtA), fetal umbilical artery (UmA), middle cerebral artery (MCA), and renal artery (RA). Umbilical artery blood gases were analysed at delivery in high risk group. RESULTS: The resistance index (RI), pulsatile index (PI) and ratio of peak systolic to least diastolic flow velocity (S/D) of UtA, UmA and RA were higher and the PI, S/D of MCA was lower significantly in the high risk group than that of normal the group (P < 0.05). In the high risk pregnancy, when UmA PO2 was less than 2.5 kPa, the S/D of UtA, PI, S/D of UmA and RI, PI, S/D of RA were increased, and the PI of MCA was decreased (P < 0.05). There were a positive correlation between PI of UmA, RA and PO2 pH of UmA, and a negative correlation between the former and PCO2 of UmA. But there were a negative correlation between PI of MCA and PO2, pH of UmA, and a positive correlation between the former and UmA PCO2. CONCLUSION: In the high risk pregnancy, fetal cerebral blood flow increased, whereas blood flow of fetal peripheral vessels (especially renal vessel) decreases. There is a good correlation between fetal hypoxia and fetal blood FVWs. The indices of the fetal blood FVMs can identify fetal hypoxia and acidosis.

Acidosis↗
PubMed1997

[Research on omni-directional ultrasonic imaging].

In this paper, an omni-direction M-mode ultrasonic imaging method is introduced, in which M-mode sample line can rotate and move freely. In this way the measurement of parameters such as amplitude and speed of movement of organs can be conducted in any position or direction. We analyzed the sources of errors of the method and the way to overcome them.

Echocardiography↗
PubMed1996

Characterization and application of soybean YACs to molecular cytogenetics.

Yeast artificial chromosomes (YACs) are widely used in the physical analysis of complex genomes. In addition to their value in chromosome walking for map-based cloning, YACs represent excellent probes for chromosome mapping using fluorescence in situ hybridization (FISH). We have screened such a library for low-copy-number clones by hybridization to total genomic DNA. Four clones were chosen for chromosome tagging based upon their low or moderate signal. By using degenerate oligonucleotide-primed PCR (DOP-PCR), we were able to use relatively small amounts of soybean YAC DNA, isolated directly by preparative pulsed-field gel electrophoresis, as FISH probes for both metaphase chromosome spreads and interphase nuclei. FISH chromosomal analysis using the three of the clones as probes resulted in relatively simple hybridization patterns consistent with a single homologous locus or two homoeologous loci. The fourth YAC probe resulted in a diffuse hybridization pattern with signal on all metaphase chromosomes. We conclude that YACs represent a valuable source of probes for chromosomal analysis in soybean.

Chromosomes, Artificial, Yeast↗
PubMed1996

Hybridization properties of oligodeoxynucleotide pairs bridged by polyarginine peptides.

The hybridization properties of a series of probes, based on two 9mer oligodeoxynucleotides (designated as I and II) having an appended oligoarginine chain (Rn) to produce peptide-oligonucleotide conjugates or peptide-bridged oligonucleotide pairs (e.g. Rn-I or II-Rn-I), were investigated. For the double-linked probes, we found that the peptide bridge induces the two 9mers to bind complementary single-stranded DNA or RNA targets with substantially enhanced thermal stability. The resulting hybrid with complementary DNA was found to assume a 1:1 complex in the B conformation as judged by UV mixing curves and CD spectroscopy. Complexes of single or double-linked probes with complementary RNA exhibited sensitivity to RNase H digestion. The influence of the identity and chirality of the repeating unit in the bridge, the length of the bridge, the gap size and the salt concentration on the hybridization properties of this new class of oligonucleotide probes was also studied. Our data reveal that these compounds exhibit properties that should prove useful in the development of antisense strategies.

Amino Acid Sequence↗