Search PubMed⌕ Search

Biomedical subjects

W K Wang

Publications and source records attributed to W K Wang.

At least 37 records · Page 2Linked to original sources
PubMed1998

CCR5 coreceptor utilization involves a highly conserved arginine residue of HIV type 1 gp120.

The seven-transmembrane CCR5 was recently found to double as a coreceptor for a genetically diverse family of human and nonhuman primate lentiviruses. Paradoxically, the main region of the envelope protein believed to be involved in CCR5 utilization was mapped to hypervariable region 3, or V3, of the envelope glycoprotein gp120. In this study, we addressed the question of whether functional convergence in CCR5 utilization is mediated by certain V3 residues that are highly conserved among HIV type 1 (HIV-1), HIV type 2, and simian immunodeficiency virus. Site-directed mutagenesis carried out on three such V3 residues revealed that the Arg-298 of HIV-1 gp120 has an important role in CCR5 utilization. In contrast, no effect was observed for the other residues we tested. The inability of Arg-298 mutants to use CCR5 was not attributed to global alteration of gp120 conformation. Neither the expression, processing, and incorporation of mutant envelope proteins into virions, nor CD4 binding were significantly affected by the mutations. This interpretation is further supported by the finding that alanine substitutions of five residues immediately adjacent to the arginine residue had no effect on CCR5 utilization. Taken together, our data strongly suggests that the highly conserved Arg-298 residue identified in the V3 of HIV-1 has a significant role in CCR5 utilization, and may represent an unusually conserved target for future anti-viral designs.

Amino Acid Sequence↗
PubMed1998

Liu-wei-dihuang: a study by pulse analysis.

Pulse analysis method was used in studying the traditional Chinese formula Liu-Wei-Dihuang as well as five of its main components (Rehmannia glutinosa, Cornus officinalis, Paeonia Suffruticosa, Poria cocos and Alisma plantogo-aquatica var oriental). Based on our recently developed resonance theory, we tried to elucidate the mechanism and mutual reactions of these meridian related herbs. Hot water herbal extracts were injected intraperitoneally into rats and the pressure pulse spectrum at the caudate artery was measured. The results of this study indicated that Liu-Wei-Dihuang mildly increased blood flow to meridians with lower resonance frequency: namely the liver C1, the kidney C2 and the spleen C3; but decreased blood flow to the higher resonance frequency organs and meridians: the lung C4, the stomach C5, the gall bladder C6, and the bladder C7. It also decreased the heart load C0. All of the five herb components increased blood flow to the kidney C2 and the spleen C3; but their effects on the high frequency organs varied. Alisma plantogo-aquatica var. oriental decreased the C0, C5, C6, C7; Poria cocos decreased C1, C4, C5, C6; Rehmannia glutinosa, Paeonia Suffruticosa decreased C0, C4, C5, C6, C7; Cornus officinalis increased C4 but decreased C0, C5, C6, C7.

Animals↗
PubMed1997

Dominant transformation by mutated human ras genes in vitro requires more than 100 times higher expression than is observed in cancers.

The gene-mutation-cancer hypothesis holds that mutated cellular protooncogenes, such as point-mutated proto-ras, "play a dominant part in cancer," because they are sufficient to transform transfected mouse cell lines in vitro [Alberts, B., Bray, D., Lewis, J., Raff, M., Roberts, K. & Watson, J. D. (1994) Molecular Biology of the Cell (Garland, New York)]. However, in cells transformed in vitro mutated human ras genes are expressed more than 100-fold than in the cancers from which they are isolated. In view of the discrepancy between the very low levels of ras transcription in cancers and the very high levels in cells transformed in vitro, we have investigated the minimal level of human ras expression for transformation in vitro. Using point-mutated human ras genes recombined with different promoters from either human metallothionein-IIA or human fibronectin or from retroviruses we found dominant in vitro transformation of the mouse C3H cell line only with ras genes linked to viral promoters. These ras genes were expressed more than 120-fold higher than are native ras genes of C3H cells. The copy number of transfected ras genes ranged from 2-6 in our system. In addition, nondominant transformation was observed in a small percentage (2-7%) of C3H cells transfected with ras genes that are expressed less than 20 times higher than native C3H ras genes. Because over 90% of cells expressing ras at this moderately enhanced level were untransformed, transformation must follow either a nondominant ras mechanism or a non-ras mechanism. We conclude that the mutated, but normally expressed, ras genes found in human and animal cancers are not likely to "play a dominant part in cancer." The conclusion that mutated ras genes are not sufficient or dominant for cancer is directly supported by recent discoveries of mutated ras in normal animals, and in benign human tissue, "which has little potential to progress" [Jen, J., Powell, S. M., Papadopoulos, N., Smith, K. J., Hamilton, S. R., Vogelstein, B. & Kinzler, K. W. (1994) Cancer Res. 54, 5523-5526]. Even the view that mutated ras is necessary for cancer is hard to reconcile with (i) otherwise indistinguishable cancers with and without ras mutations, (ii) metastases of the same human cancers with and without ras mutations, (iii) retroviral ras genes that are oncogenic without point mutations, and (iv) human tumor cells having spontaneously lost ras mutation but not tumorigencity.

Animals↗
PubMed1997

Pulse spectrum study on the effect of sie-zie-tang and Radix aconiti.

Extracts of the traditional Chinese formula Sie-Zie-Tang as well as one of its main components, Radix Aconiti were injected into rats intraperitoneally to observe pressure wave spectrum changes at the caudate artery. We found that Radix Aconiti decreased the C0 (DC term of the pulse), C5 and C6 (the harmonic proportions of the 5th and the 6th harmonic), but increased C2 and C3 (the harmonic proportions of the second and the third harmonic) significantly. For Sie-Zie-Tang, the increases of C2, C3, and C4 were accompanied by the decreasing of C0. The decreases of C5, C6 were small and not significant. The additional ingredients in the formula reduce toxic side effects (arrhythmia or heart failure caused by faster and stronger heart beat) due to Radix Aconiti. For human subjects, low dose Sie-Zie-Tang tends to normalize the Fourier components of the pressure wave. Orally taking the formula elevates the harmonic proportion of the harmonic that is lower than normal, but suppresses the higher one. Our results provides a possible mechanism for heart meridian related herbs. It strengthens heart beats, and normalizes energy distribution to different meridians. The study on Sie-Zie-Tang reveals another formula construction to reduce toxic side effects.

Adult↗
PubMed1997

Genetic variation within human immunodeficiency viruses generates rapid changes in tropism, virulence, and transmission.

The human immunodeficiency viruses (HIV-1) undergo high rates of variation. Only a few point mutations in the envelope gene are required to switch the tropism of HIV-1 from a growth preference for monocytes to lymphocytes or to acquire lytic properties for rapid killing of infected T4 lymphocytes. Since heterosexual transmission efficiency is high for HIV-1's that are most prevalent in Africa or Asia, but low for HIV-1 B, which dominates in the US and western Europe, we asked whether African and Asian viruses had a particular tropism for cells of the reproductive tract. Langerhans' cells (LC), showed only minimal susceptibility to infection with HIV-1B from the US, but substantially greater sensitivity for infections by HIV-1 E and HIV-1 C, subtypes that predominate in Asia and Africa.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Pattern of gp120 sequence divergence linked to a lack of clinical progression in human immunodeficiency virus type 1 infection.

Differential rates of AIDS development and/or T4 lymphocyte depletion in HIV-1-infected individuals remain unexplained. The hypothesis that qualitative differences in selection pressure in vivo may account for different rates of disease progression was addressed in nine eligible study participants from a cohort of 315 homosexual men who have been followed since 1985. Disproportionately fewer changes in variable regions and more in C3 of gp12O were found to be significantly associated with slower disease progression. Our finding provides the first example to demonstrate that differential selection pressure related to the emergence of HIV-1 variants is associated with long term nonprogression. Candidate vaccines that elicit strong selection pressure on C3 of gp120 are likely to provide better protection than those targeting variable regions.

Base Sequence↗
PubMed1996

Identification of the envelope V3 loop as a determinant of a CD4-negative neuronal cell tropism for HIV-1.

Some neuronal-derived CD4-negative cells are susceptible to infection with human immunodeficiency virus type 1 (HIV-1). Galactosyl ceramide is an alternate receptor for HIV-1 that appears to bind in vitro to the C2, V3, V4, and V5 regions of gp120. Amino acid variation in the V3 loop of HIV-1 affects cellular tropism in CD4-positive cells, but its effect on CD4-negative cells has not been fully analyzed. Here, we describe the effect of amino acid changes in V3 on the HIV-1 infection of a CD4-negative neuronal cell line, SK-N-MC. The sequence of the V3 domain was found to dramatically alter virus infectivity. Furthermore, a gp120 V3 loop neutralizing monoclonal antibody blocked HIV-1 infection of SK-N-MC cells. This data suggests that V3 may also serve as a primary viral determinant for infectivity of CD4-negative cells.

Amino Acid Sequence↗
PubMed1996

Single amino acid substitution in constant region 1 or 4 of gp120 causes the phenotype of a human immunodeficiency virus type 1 variant with mutations in hypervariable regions 1 and 2 to revert.

The second major cysteine loop of human immunodeficiency virus type 1 envelope glycoprotein gp120 contains 5 to 11 consensus N-linked glycosylation sites, which is disproportionately higher than the number of such sites found in other regions of gp120. Amino acid substitutions introduced at three of six N-linked glycosylation sites in this region of an infectious molecular clone, HXB2, resulted in severe impairment of virus infectivity. Isolation and genetic characterization of a revertant of this mutant revealed an isoleucine-for-valine substitution at position 84 in constant region 1 and an isoleucine-for-methionine substitution at position 434 in constant region 4. Further mutational analysis indicated that either isoleucine substitution was sufficient to confer the revertant phenotype. These findings demonstrate that V1/V2 not only functionally interacts with C4, as previously reported, but also interacts with C1. The observation that compensatory changes do not involve regeneration of N-linked glycosylation sites in the second major cysteine loop suggests that replication of human immunodeficiency virus type 1 in vitro is independent of the presence of a disproportionate number of N-linked glycosylation sites within this loop.

Amino Acid Sequence↗
PubMed1996

The prandial effect on the pulse spectrum.

The prandial effect on the pulse spectrum of the radial artery was studied. Ingestion greatly affected the spectrum of the pressure pulse. For most of the tested subjects, the harmonic proportions of the 2nd and the 4th harmonic increased significantly after ingestion, however a decreasing effect was found on the 5th, 6th, 7th, 8th, 9th harmonics. The spectrum became stable from half hour after ingestion and last 3 to 4 hours. From these results, a reliable pulse diagnosis is therefore suggested to be done in the period when the pulse spectrum is stable; physiological significance of these postprandial phenomena is also discussed.

Adult↗
PubMed1996

Pulse spectrum analysis of chemical factory workers with abnormal blood test.

Double blind tests to check the correlation between pulse diagnosis and liver function tests were performed. Blood tests including T-Bil, D-Bil, SGOT and SGPT of 70 chemical factory workers were compared with pulse analysis. Special attention was paid to the indicators of liver and lung meridians for pulse diagnosis. It was found that using the criterion (1) C1 > or = 3+ and C1 + C4 > or = 4+ (hyperfunction) and (2) C1 < or = 3-(hypofunction) as abnormal liver meridian (for C1, every 5% above normal give one +, every 5% below normal give one-; for C4 every 10% above normal give one +, every 10% below normal give one -). The correlation or agreement between the blood tests and the pulse diagnosis was very high (noncorrelation chance checked by X2-test, P < 0.001, degree of agreement checked by Kappa test Ka = 0.61 which means a substantial relationship). Suggestions such as more tests, more criteria and precautions for future study are also proposed.

Adult↗
PubMed1996

Effect of acupuncture at tai-tsih (K-3) on the pulse spectrum.

The frequency specific acupuncture effect on Tai-Tsih (K-3) was examined by investigating pulse variations at the radial artery. The harmonic proportions of the 2nd, 3rd, and the 4th harmonics were increased but the 5th, 6th and 9th harmonics were decreased significantly. The phase angles of all except the 2nd harmonic were increased (wave propagated slower). These results are compared with the frequency specific acupuncture effect on Tsu-San-Li (St-36) which we reported previously (Wang et al., 1995a). This study solidified the weak coupling resonance theory, which successfully explains these frequency specific effects as well as the acupuncture mechanism.

Acupuncture Therapy↗
PubMed1996

Pulse spectrum analysis of hospital patients with possible liver problems.

Pulse diagnosis were performed on 85 patients who came to the hospital for liver and gall-bladder problems. Correlation between liver tests, which include T-Bil, D-Bil, SGOT, SGPT, ZTT, Alp, gamma-GT, Cho, Alb, and ultra sound scanning, and pulse diagnosis were analyzed. 77 out of 85 subjects showed abnormal liver tests. We used the following 5 criteria for pulse diagnosis as liver abnormality to test the correlation: (1) C1 > or = 3+ and C1 + C4 > or = 4+ or C1 + C6 > or = 4 (in intensity); (2) C1 < or = 3 (in intensity); (3) C6 > or = 3 and C1 + C6 > or = 4 (in intensity); (4) C6 < or = -2 (in intensity) and C6 < or = -2 (in the phase) and (5) C1 > or = 2 C3 < or = -2 (in intensity) or C3 < or = -2 (in the phase). For C1 (liver) every 5% above normal was given one "+," every 5% below normal was given one "-." For C3 (spleen), C4 (lung), C6 (gall-bladder), every 10% above normal was given one "+,", every 10% below normal was given one "-." For the phase, every 10% delay in the traveling speed was given one "-." When considering only the "+" and "-" states and neglecting the quantity of "+" and "-," there are 2(11) (from intensity) x 2(11) (from phase), which equal 2048 x 2048 possible states in the pulse analysis. We considered only 5 criteria for liver abnormality; the correlation was still very high, p < 0.0002, kappa = 0.64. It strongly suggests that meridian theory and pulse diagnosis have physiological and pathological importance.

Adolescent↗
PubMed1995

Product inhibition of the recombinant CelS, an exoglucanase component of the Clostridium thermocellum cellulosome.

CelS is the most abundant subunit and an exoglucanase component of the Clostridium thermocellum cellulosome, multicomponent cellulase complex. The product inhibition pattern of CelS was examined using purified recombinant CelS (rCelS) produced in Escherichia coli. The rCelS activity on cellopentaose was strongly inhibited by cellobiose. The rCelS activity was also inhibited by lactose. Glucose was only marginally inhibitory. Cellobiose appeared to inhibit the rCelS activity through a competitive mechanism. The inhibition was relieved when beta-glucosidase was added, presumably because of the conversion of cellobiose into glucose. These hydrolysis product inhibition patterns are consistent with those of the crude enzyme (cellulosome), suggesting that CelS is a rate-limiting factor in the activity of the cellulosome.

Cellobiose↗
PubMed1995

Exoglucanase activities of the recombinant Clostridium thermocellum CelS, a major cellulosome component.

The recombinant CelS (rCelS), the most abundant catalytic subunit of the Clostridium thermocellum cellulosome, displayed typical exoglucanase characteristics, including (i) a preference for amorphous or crystalline cellulose over carboxymethyl cellulose, (ii) an inability to reduce the viscosity of a carboxymethyl cellulose solution, and (iii) the production of few bound reducing ends on the solid substrate. The hydrolysis products from crystalline cellulose were cellobiose and cellotriose at a ratio of 5:1. The rCelS activity on amorphous cellulose was optimal at 70 degrees C and at pH 5 to 6. Its thermostability was increased by Ca2+. Sulfhydryl reagents had only a mild adverse effect on the rCelS activity. Cellotetraose was the smallest oligosaccharide substrate for rCelS, and the hydrolysis rate increased with the substrate chain length. Many of these properties were consistent with those of the cellulosome, indicating a key role for CelS.

Base Sequence↗
PubMed1995

The highly conserved aspartic acid residue between hypervariable regions 1 and 2 of human immunodeficiency virus type 1 gp120 is important for early stages of virus replication.

Between hypervariable regions V1 and V2 of human immunodeficiency virus type 1 (HIV-1) gp120 lies a cluster of relatively conserved residues. The contribution of nine charged residues in this region to virus infectivity was evaluated by single-amino-acid substitutions in an infectious provirus clone. Three of the HIV-1 mutants studied had slower growth kinetics than the wild-type virus. The delay was most pronounced in a mutant with an alanine substituted for an aspartic acid residue at position 180. This aspartic acid is conserved by all HIV-1 isolates with known nucleotide sequences. Substitutions with three other residues at this position, including a negatively charged glutamic acid, all affected virus infectivity. The defect identified in these mutants suggests that this aspartic acid residue is involved in the early stages of HIV-1 replication.

Amino Acid Sequence↗