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Biomedical subjects

T Liu

Publications and source records attributed to T Liu.

At least 469 records · Page 26Linked to original sources
PubMed1989

Effect of recombinant soluble CD4 in rhesus monkeys infected with simian immunodeficiency virus of macaques.

The CD4 molecule is a high-affinity cell-surface receptor for the human immunodeficiency virus (HIV-1) and a soluble truncated form of CD4 produced by recombinant DNA technology is a potent inhibitor of HIV-1 replication and HIV-1-induced cell fusion in vitro. Rhesus monkeys infected with the simian immunodeficiency virus of macaques (SIVMAC), a virus closely related to HIV-1, develop an AIDS-like syndrome, and so provide an important model for the evaluation of potential AIDS therapies. We have assessed the therapeutic effect of recombinant soluble CD4 in SIVMAC-infected rhesus monkeys. Virus was readily isolated from peripheral blood lymphocytes and bone marrow cells of these animals before starting treatment with soluble CD4, but became difficult to isolate soon after treatment had begun. Moreover the diminished growth of both granulocyte-macrophage and erythrocyte progenitor colonies from the bone marrow of these monkeys rose to normal levels during treatment. These findings indicate that soluble CD4 could prove valuable in the treatment of AIDS.

Animals↗
PubMed1989

Prognostic value of lupus band test in unexposed normal skin of patients with systemic lupus erythematosus.

Biopsy specimens of normal unexposed buttock skin were taken from 71 patients with systemic lupus erythematosus (SLE) for lupus band test (LBT). Correlation of positive incidence, fluorescent intensity, protein classes and numbers of LBT with SLE activity including active nephropathy were studied. Positive LBT results are associated with SLE disease activity, decreased CH50 and C3, ANA peripheral pattern and positive AdsDNA antibodies, but not with active nephropathy per se. Although LBT results of unexposed normal skin can reflect SLE activity, its prognostic value should not be overestimated.

Adolescent↗
PubMed1989

[Study on "massage to activate the meridian" apparatus in the treatment of cholecystolithiasis].

This apparatus is designed in accordance with the doctrine and principles of traditional Chinese medicine and based on the theory of meridian and specific massage procedure in conjunction with the "Information Theory" and electron utilizing technique. It utilizes a programmed induction "Special Wave" to stimulate a series of acupuncture points, combined with administration of western drugs from a regime of "General Attack" treatment on the gallbladder stones, to enhance their evacuation. By stimulating the specific acupuncture points with this apparatus through the action of "Special Wave" strong contraction of the gallbladder can be elicitated. Experiments on dogs showed that under such stimulation the intra-gallbladder pressure can be increased 26 times, producing a jet of bile flow which facilitates the expulsion and evacuation of stones in the gallbladder. Method of use: first place a conductive rubber pad on the acupuncture point to be stimulated, then use a hand-held electrode to massage-stimulate the meridian. It is carried out forward and backward along the direction of meridian. The whole procedure is carried out under direct visualization with the help of ultrasonic B-scan. When dilatation of the common bile duct is observed, the hand-help electrode is used to perform push-compress massage on the meridian, and acupuncture points making the stones enter the common bile duct B-scan give proper orientation for the manipulation. This method has been tested clinically on 410 patients with good results. The evacuation rate of the gallbladder stones was 92.7% with complete evacuation achieved in 17.3%.(ABSTRACT TRUNCATED AT 250 WORDS)

Acupuncture Therapy↗
PubMed1988

HIV infection is blocked in vitro by recombinant soluble CD4.

The T-cell surface glycoprotein, CD4 (T4), acts as the cellular receptor for human immunodeficiency virus, type 1 (HIV-1), the first member of the family of viruses that cause acquired immunodeficiency syndrome. HIV recognition of CD4 is probably mediated through the virus envelope glycoprotein (gp120) as shown by co-immunoprecipitation of CD4 and gp120 (ref.5) and by experiments using recombinant gp120 as a binding probe. Here we demonstrate that recombinant soluble CD4(rsT4) purified from the conditioned medium of a stably transfected Chinese hamster ovary cell line is a potent inhibitor of both virus replication and virus-induced cell fusion (syncytium formation). These results suggest that rsT4 is sufficient to bind HIV, and that it represents a potential anti-viral therapy for HIV infection.

Animals↗
PubMed1988

Effect of recombinant soluble CD4 on human peripheral blood lymphocyte responses in vitro.

We have previously demonstrated that recombinant soluble CD4 protein (rsT4) blocks both HIV-1 infection of CD4 bearing lymphocytes and syncytium formation in vitro. (Recombinant soluble CD4 is designated by rsT4). Hence, we suggested the use of rsT4 in therapy for AIDS or the prevention of HIV-1 infection in individuals with a known risk of exposure. However, concerns arose that rsT4 might be immunosuppressive because of its implicated role in the enhancement of certain lymphocyte activation events through its engagement of MHC class II molecules on target cells. We therefore assessed the effect of recombinant soluble CD4 upon a number of functional and activation parameters of lymphocytes, including cellular proliferation, IL-2 secretion, and cytolytic capability, after antigenic or mitogenic stimulation. We report here that rsT4, at 60-fold over the concentration needed to block acute HIV-1 infection in vitro, does not significantly inhibit the activation of human peripheral blood lymphocytes by either PHA, tetanus toxoid or allogeneic cells. These results indicate that rsT4 will potentially exert minimal immunosuppressive effects in vivo, thus supporting the feasibility of clinical trials of rsT4 in the treatment or prevention of AIDS. In addition, the implications of these results for the interactions between CD4 and MHC class II molecules during lymphocyte activation are discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Structural analysis of the locus containing the human C-reactive protein gene and its related pseudogene.

The gene for human C-reactive protein (CRP) is mapped within a 34-kilobase pair genomic DNA segment identified by chromosome walking through overlapping DNA fragments cloned into a lambda phage library. Within 16 kilobase pairs upstream and downstream of the locus for the authentic CRP gene, only one other sequence homologous to that for CRP could be found. Sequencing analysis indicates this sequence to be a pseudogene with 50-80% region-specific homology. Comparison of the authentic CRP gene cloned from genomic DNA libraries independently prepared from three patients indicates no difference in the 5' and 3' flanking region, promoter region, or coding sequence. Only a polymorphism in the length of the poly(GT) stretch located in the intron is observed. There appears to be only one gene locus and copy per haploid chromosome for the authentic CRP gene and its pseudogene.

Bacteriophage lambda↗
PubMed1987

Purification and characterization of serotype 6 fimbriae from Bordetella pertussis and comparison of their properties with serotype 2 fimbriae.

Fimbriae were removed from Bordetella pertussis (serotype 1.3.6) by mechanical shearing and purified by precipitation with ammonium sulfate, pH-dependent precipitation at pH 7.4, followed by two successive extractions of the precipitated fimbriae with 4 M urea. By electron microscopy, the precipitated fimbriae appeared as aggregated bundles of long, relatively straight filaments which were disaggregated to individual flexuous filaments at pH 10.5. These purified fimbriae were identified as serotype 6 agglutinogens, since antibody to the purified fimbriae agglutinated B. pertussis strains serotyped as 1.3.6, 1.2.3.6, or 1.2.3.4.6 but did not agglutinate strains of serotype 1.2.3.4, 1.2.3, or 1.3. In contrast, antibody to serotype 2 fimbriae only agglutinated B. pertussis strains containing serotype 2 agglutinogen. Purified type 6 and 2 fimbriae were found to be weakly cross-reactive by enzyme-linked immunosorbent assay, using polyclonal antibody to each type of fimbria. In an immunoblot assay, polyclonal antibodies to a 22,000-dalton subunit of fimbriae from B. bronchiseptica reacted strongly with the type 2 fimbrial subunit of B. pertussis, but only weakly with the type 6 subunit. When subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the protein subunit of the type 6 fimbriae migrated with a molecular weight of 21,500, whereas the type 2 fimbrial subunit had a molecular weight of 22,000. The two types of subunits had similar amino acid compositions and showed amino-terminal sequence homology in 15 of 21 amino acids. The amino-terminal amino acid sequences of the B. pertussis fimbriae were distinct from those reported for fimbriae from other gram-negative bacteria. Neither the type 6 nor the type 2 fimbriae caused hemagglutination when assayed with several types of erythrocytes.

Amino Acid Sequence↗
PubMed1986

[[Demographic aspects of urbanization in the Lower Yangtze region in China, circa 1500-1900]].

Urbanization trends in the Lower Yangtze region of China from 1500 to 1900 are examined. Data are from a variety of sources, including genealogies, local records, and other literature. An attempt is made to analyze the demographic characteristics of the urban population. "The demographic characteristics in respect to marriage, fertility and mortality found from the genealogies do reveal that there were dissimilarities between the rural and urban dwelling populations. Moreover, findings related to migration tend to support that rural to urban migration was an important factor that speeded up urbanization in the Lower Yangtze Region." (SUMMARY IN ENG)

Asia↗
PubMed1986

Agricultural change and population growth: a brief survey on the case of China in historical perspective.

A historical review of the relationship between agricultural change and population growth in China is presented. "This paper will try to discuss four aspects of agricultural change that are related to population growth. They are: (1) expansion of agricultural frontier, (2) changes in cultivation methods and land use, (3) improvements in agricultural technology, and (4) irrigation and water-control. Each of these aspects [is] treated briefly with temporal and spatial perspectives...." The relevance of the Boserup theory that population pressure leads to agricultural development is considered in the Chinese context. It is found that some evidence supports the theory. (summary in CHI)

Agriculture↗
PubMed1985

Pertussis toxin-catalyzed ADP-ribosylation of transducin. Cysteine 347 is the ADP-ribose acceptor site.

Pertussis toxin catalyzes the transfer of ADP-ribose from NAD to the guanine nucleotide-binding regulatory proteins Gi, Go, and transducin. Based on a partial amino acid sequence for a tryptic peptide of ADP-ribosylated transducin, asparagine had been characterized as the site of pertussis toxin-catalyzed ADP-ribosylation. Subsequently, cDNA data for the alpha subunit of transducin indicated that the putative asparagine residue was, in fact, not present in the protein. To determine the amino acid that served as the ADP-ribose acceptor, radiolabel from [adenine-U-14C]NAD was incorporated, in the presence of pertussis toxin, into the alpha subunit of transducin (0.3 mol/mol). An ADP-ribosylated, tryptic peptide was purified and fully sequenced by automated Edman degradation. The amino acid sequence, Glu-Asn 343-Leu-Lys-Asp 346-X-Gly 348-Leu-Phe, corresponds to the cDNA sequence coding the carboxyl-terminal nonapeptide, Glu 342-Phe 350, which includes by cDNA sequence cysteine at position 347. Neither Asn 343 nor Asp 346 appeared to be modified; residue 347 adhered to the sequencing resin. Cysteine, the missing residue, was eluted from the sequencing resin with acetic acid along with 76% of the peptide-associated radioactivity, half of which, presumably ADP-ribosylcysteine, eluted from an anion exchange column between NAD and ADP-ribose; the other half had a retention time corresponding to 5'-AMP. We conclude that Cys 347 and not Asn 343 or Asp 346 is the site of pertusis toxin-catalyzed ADP-ribosylation in transducin.

Adenosine Diphosphate Ribose↗
PubMed1985

Genomic DNA sequence for human C-reactive protein.

The gene for the prototype acute phase reactant, C-reactive protein, has been isolated from two lambda phage libraries containing inserted human DNA fragments using synthetic oligonucleotide probes. Nucleotide sequence analysis indicates that after coding for a signal peptide of 18 amino acids and the first two amino acids of the mature protein, there is an intron of 278 base pairs followed by the nucleotide sequence for the remaining 204 amino acids. The intron is unusual in that it contains on the positive strand a poly(A) stretch 16 nucleotides long and a poly(GT) region 30 nucleotides long which could adopt the Z-form of DNA. The nucleotide sequence reported here confirms the amino acid sequence of mature C-reactive protein as originally reported except that it codes for an additional 19 amino acids beginning at position 62. Thus DNA sequence analysis predicts that the mature protein consists of 206 amino acids rather than 187 as originally reported. The mRNA cap site is located 104 nucleotides from the start of the signal peptide and there is a 3' noncoding region 1.2 kilobase pairs in length. The gene has a typical promoter containing the sequences TATAAAT and CAAT 29 and 81 base pairs upstream, respectively, of the cap site.

Amino Acid Sequence↗
PubMed1985

Effect of a cyclic hexapeptide analog (L363,586) of somatostatin on the function of pancreas grafts in dogs.

Complications related to the exocrine secretions cause some pancreas grafts to fail in the early postoperative period. Somatostatin inhibits exocrine secretion, as well as insulin and glucagon release. L363,586 is a cyclic hexapeptide analog of somatostatin that is 50 to 100 times more potent than the native hormone in inhibiting islet hormone release. In a preliminary experiment in which permanent fistulas were created in two dogs, we demonstrated that L363,586 (0.3 micrograms/kg/60 min) results in a fourfold decrease in pancreatic exocrine secretion when measured for 210 min following a beef meal. In a separate experiment, five totally pancreatectomized dogs who received segmental pancreas autografts with pancreaticoductocystostomy 10 months previously had L363,586 (0.3 micrograms/kg/hr) administered by the Alzet osmotic pump subcutaneously for 7 days. Mean (+/-SE) daily serum amylase activity (IU/dl) during the week before the implant was 78 +/- 3, during the week of infusion was 65 +/- 2 (P less than 0.001), and during the week afterward was 76 +/- 2. In a prospective experiment, 12 totally pancreatectomized dogs received segmental pancreas autografts with anastomosis of the graft vessels to the iliac vessels and of the pancreatic duct to the bladder. L363,586 was administered by osmotic pump for 7 days to seven dogs at a dose of 0.3 micrograms/kg/hr. Mean (+/-SE) daily serum amylase levels at 1, 2, and 3 weeks posttransplant were 223 +/- 17, 81 +/- 3, and 82 +/- 5 in the L363,586-treated dogs and 229 +/- 18, 108 +/- 5, and 90 +/- 5 in the five untreated dogs (P less than 0.001 at 2 weeks).(ABSTRACT TRUNCATED AT 250 WORDS)

Amylases↗
PubMed1984

Purification and properties of a plasmid-encoded 2,4-dichlorophenol hydroxylase.

2,4-Dichlorophenol hydroxylase, an enzyme involved in the bacterial degradation of the herbicide 2,4-dichlorophenoxyacetate (2,4-D) was purified from two bacterial strains that harbored the same 2,4-D plasmid, pJP4. The purified enzymes (Mr 224 000) from the two transconjugants were indistinguishable; they contained FAD and were composed of non-identical subunits, Mr 67 000 and 45 000, respectively. Various substituted phenols were hydroxylated, using either NADH or NADPH. The amino acid composition of the native enzyme was determined.

Acinetobacter↗