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S Weng

Publications and source records attributed to S Weng.

At least 55 records · Page 3Linked to original sources
PubMed1999

[Study on the ingredients of reserpine by TLC-FT-SERS].

A new method for analysing the ingredients of reserpine by thin layer chromatography (TLC) and surface-enhanced Raman spectroscopy (SERS) is reported in this paper. The results show that the characteristic spectral bands of reserpine satuated at the thin layer with the amount of sample about 2 microg were obtained. The difference between SERS and solid spectra was found. An absorption model of reserpine and silver sol was proposed. This method can be used to analyse the chemical ingredients with high sensitivity.

Chromatography, Thin Layer↗
PubMed1998

Comparison of the complete protein sets of worm and yeast: orthology and divergence.

Comparative analysis of predicted protein sequences encoded by the genomes of Caenorhabditis elegans and Saccharomyces cerevisiae suggests that most of the core biological functions are carried out by orthologous proteins (proteins of different species that can be traced back to a common ancestor) that occur in comparable numbers. The specialized processes of signal transduction and regulatory control that are unique to the multicellular worm appear to use novel proteins, many of which re-use conserved domains. Major expansion of the number of some of these domains seen in the worm may have contributed to the advent of multicellularity. The proteins conserved in yeast and worm are likely to have orthologs throughout eukaryotes; in contrast, the proteins unique to the worm may well define metazoans.

Animals↗
PubMed1998

Association of HLA profiles with early plasma viral load, CD4+ cell count and rate of progression to AIDS following acute HIV-1 infection. Multicenter AIDS Cohort Study.

BACKGROUND: Host genetic factors, such as HLA alleles, play an important role in mediating the course of HIV-1 disease progression through largely undefined mechanisms. OBJECTIVES: To examine the association of HLA markers with HIV-1 RNA plasma viral load and other factors associated with course of disease progression in HIV-1 infection. DESIGN AND METHODS: A group of 139 HIV-1 seroconverters from the Multicenter AIDS Cohort Study had been typed for a variety of HLA markers. HIV-1 RNA plasma viral load was measured from frozen plasma specimens obtained approximately 9 months following seroconversion. CD4+ cell counts were available from the same study visit. Statistical analysis was performed using survival techniques and linear regression models to quantify the relative associations of an HLA score profile, HIV-1 RNA plasma viral load, CD4+ cell count and age with each other and with rate of progression to AIDS and death. RESULTS: Cox proportional hazards models showed statistically significant differences in time to AIDS by HLA score profile category per unit increase [relative hazard (RH), 0.64; P < 0.0001], HIV-1 RNA plasma viral load per 10-fold increase (RH, 2.04; P = 0.0003), and CD4+ cell count per 100 cell (x 10(6)/l) increase (RH, 0.90; P = 0.02). Multivariate linear regression showed that viral load was 39% lower (P = 0.0001) for each unit increase in HLA score profile and 13% lower (P = 0.002) for each 100 cell (x 10(6)/l) increase in CD4+ cell count. CONCLUSION: The means by which the HLA score profile influences the time to AIDS is probably through immunologic responses that affect the rate of HIV-1 replication, as manifested by the HIV-1 RNA plasma viral load during the first 6-12 months following acute infection.

Acquired Immunodeficiency Syndrome↗
PubMed1998

SGD: Saccharomyces Genome Database.

The Saccharomyces Genome Database (SGD) provides Internet access to the complete Saccharomyces cerevisiae genomic sequence, its genes and their products, the phenotypes of its mutants, and the literature supporting these data. The amount of information and the number of features provided by SGD have increased greatly following the release of the S.cerevisiae genomic sequence, which is currently the only complete sequence of a eukaryotic genome. SGD aids researchers by providing not only basic information, but also tools such as sequence similarity searching that lead to detailed information about features of the genome and relationships between genes. SGD presents information using a variety of user-friendly, dynamically created graphical displays illustrating physical, genetic and sequence feature maps. SGD can be accessed via the World Wide Web at http://genome-www.stanford.edu/Saccharomyces/

Base Sequence↗
PubMed1998

AtDB, the Arabidopsis thaliana database, and graphical-web-display of progress by the Arabidopsis Genome Initiative.

AtDB, the Arabidopsis thaliana Database, has a primary role to provide public access to the collected genomic information for A. thaliana via the World Wide Web (URL: http://genome-www.stanford. edu/ ). AtDB presents interactive physical and genetics maps that are hyperlinked with detailed information about the clones and markers placed on these maps. A large literature collection on Arabidopsis , contact information on researchers worldwide, laboratory method manuals and other information useful to plant molecular biologists are also provided. This paper discusses the database-driven clickable displays that provide easy navigation within a variety of genomic maps, including those summarizing progress of the international Arabidopsis genomic sequencing effort, AGI (the Arabidopsis Genome Initiative). The interface uses client-side hyperlinked GIF-images that direct the user to detailed database-information. A new BLAST service is also described. This gives users access to the thousands of Arabidopsis BAC clone end-sequences and includes hyperlinked images summarizing the search results. The linking of genetic and physically mapped regions and their sequence into information for loci within that region is an ongoing goal for this project.

Arabidopsis↗
PubMed1998

Seasonal patterns of deaths in Matlab, Bangladesh.

BACKGROUND: Deaths exhibit a seasonal pattern in most parts of the world. Analyses of deaths for the years 1972-1974 from the vital registration system of Matlab, Bangladesh, published in this journal 17 years ago, showed sinusoidal seasonal patterns. As death rates have declined in other nations, the seasonal pattern is attenuated. Death rates have declined substantially in Bangladesh in the past two decades. Thus, the present study examines monthly counts of deaths from Matlab data for a period 15 years later and tests the hypothesis of a decrease or shift in seasonality over time. METHODS: Trigonometric regression models were fit to monthly data by age and cause of death from the Matlab vital registration system for the years 1982-1990. A total of 20,328 death records were available for analyses. RESULTS: In the recent period significant sinusoidal seasonal patterns are found in all but one of the age and cause of death groups. Total deaths peak in the winter as do neonatal deaths but post-neonatal and child deaths are maximum in April and July respectively. Among cause groups, injury deaths (mostly attributed to drowning) show the greatest seasonal swing. The time of peak has only shifted for one age group--neonates--since the 1972-1974 period. The magnitude of the seasonal swing has declined significantly only for the neonatal age group and injury cause of death group. CONCLUSION: Marked seasonal patterns of deaths persist in the Matlab area of Bangladesh even as the level of mortality has declined.

Adolescent↗
PubMed1998

Perinatal human immunodeficiency virus-1 transmission and intrauterine growth: a cohort study in Butare, Rwanda.

OBJECTIVE: To study the association of perinatal human immunodeficiency virus (HIV)-1 transmission with birth outcomes, including birth weight, gestational age, ponderal index, head circumference, and weight/head ratio. METHODS: Data from a prospective cohort study of 627 pregnant women and their infants in Butare, Rwanda, from October 1989 until April 1994 were analyzed. A total of 318 HIV-1-infected and 309 seronegative women were enrolled during pregnancy and gave birth to 590 live singletons. Multiple linear regression modeling was used to assess the association of mother-child HIV status with several birth outcome measures. RESULTS: Unadjusted mean birth weight of HIV- infected infants was 235 g (95% confidence interval [CI] = 94 to 376 g) less than that of HIV-uninfected infants born to HIV-positive mothers (the reference group). After adjustment for gestational age, socioeconomic factors, maternal age, parity, hematocrit, and anthropomorphic measures, mean birth weight of HIV-infected infants was 154 g (95% CI = 38 to 271 g) lower than that of the reference group. When infants born to HIV-seronegative mothers were compared with the reference group, mean birth weights did not differ. Adjusted models resulted in estimates of mean head circumference 0.6 cm smaller (95% CI = 0.2 to 1.1 cm), ponderal index 0.14 lower (95% CI = 0.05 to 0.23), weight/head ratio 3.5 lower (95% CI = 0.5 to 6.4), and gestational age 0.5 weeks shorter (95% CI = 0.1 to 0.9 weeks) for HIV-infected infants than for the reference group. CONCLUSIONS: After adjustment for potential confounding variables, this study showed statistically significant differences in birth weight, gestational age, ponderal index, and weight/head ratio when HIV-infected infants were compared with noninfected infants born to HIV-positive mothers. HIV-1, mother-to-child transmission, Africa, intrauterine growth, birth weight, gestational age, ponderal index.

Acquired Immunodeficiency Syndrome↗
PubMed1998

[HBV markers in severe hepatitis B].

In order to elucidate the relationship between hepatitis B virus (HBV) replication and severity of hepatitis B, HBV serological markers and HBV-DNA in 56 patients with chronic hepatitis B were detected using the methods of ELISA and PCR, respectively. The results showed that the positive prevalence of HBeAg and/or HBV-DNA in chronic severe hepatitis B (5/25) was much lower than that in non-severe chronic hepatitis B (26/31) (P < 0.01). The study provides the suggestive evidence that viral replication is significantly reduced in severe hepatitis B. Also, increased replication of HBV appears to be not the cause of hepatic necrosis in severe hepatitis B.

Adult↗
PubMed1998

[FTIR study on structure of pearl and nacre of mollusk shell].

Pearl and nacre of mollusk shell (Hyriopsis cumingii) were studied with high resolution Fourier transformation infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results of X-ray diffraction indicate that the samples are still aragonite after thermal treatment at 160 degrees C for 5hr, however, the significant variations of peak position and band width of FTIR spectra reveal the interaction between organic matrix and inorganic crystal in biomineralized materials. The variations of spectra were studied by a curve-fitting algorithm and the band related to the interaction is revealed.

Animals↗
PubMed1998

[Comparative study on the hydration of phosphate group in H2O/NaDEHP/n-heptane and H2O-TBP systems by FT-IR].

The hydrations of phosphate group in both tributyl phosphate (TBP)-H2O system and water/NaDEHP/n-heptane reverse micellar system have been studied using Fourier transform infrared spectroscopy (FT-IR). Water content (W0 = [H2O]/[TBP]) in TBP solutions was measured quantitatively using FT-IR. In water/NaDEHP/n-heptane reverse micellar system, the stretching frequencies of phosphate group shifted from 1229 to 1200cm(-1) when water content increased from 1 to 25. For TBP-H2O system, P=O stretching band varied from 1281.33 to 1263cm(-1) with the increasing water content (from 0.33 to 1.55). P=O stretching bands in TBP-H2O system were also found to split into two peaks located around 1283 and 1260cm(-1) after the bands were resolved by curve-fitting. All these variations are attributed to the hydration of phosphate in the two systems.

English Abstract↗
PubMed1998

[FT-IR study on the solid-state reaction of bilirubin on BaF2].

Bilirubinate complexes are the main component of pigment gallstones and the recent researches suggested that bilirubin free radical plays a role in some biological processes. In this paper the solid-state reaction of bilirubin on BaF2 was examined by FT-IR. The solid-state reaction was produced by grinding the crystalline bilirubin and single crystals BaF2 together in an agate mortar. From the results the free radical mechanism is suggested in the solid-state reaction of bilirubin on BaF2. The replacement of H on NH of pyrrole by Ba2+ was prior to that of H on COOH. The structure of the resultant complex from the solid-state reaction is different compared with that from the liquid-state reaction.

Barium Compounds↗
PubMed1998

Encapsulation of the topoisomerase I inhibitor GL147211C in pegylated (STEALTH) liposomes: pharmacokinetics and antitumor activity in HT29 colon tumor xenografts.

The topoisomerase I inhibitor GL147211C [7-[(4-methylpiperazino)methyl]-10,11-(ethylenedioxy)-(20S)-campto thecin trifluoroacetate], a camptothecin analogue, has significant activity in tumor cell cytotoxicity assays in vitro and antitumor activity in both animal tumor models and human patients. Its toxicity is significant, however, effectively limiting the amount of drug that can be administered and its clinical utility. To determine whether the therapeutic index of GL147211C could be improved, the drug was encapsulated in long-circulating, pegylated (STEALTH) liposomes (SPI-355). The pharmacokinetics and antitumor activity of SPI-355 were compared to those of nonliposomal GL147211C. The plasma pharmacokinetics of SPI-355 in rats were typical of those of other pegylated liposomal formulations, with significantly increased blood circulation time; the dose-corrected area under the curve and Cmax of SPI-355 (10 mg/kg) were 1250- and 35-fold higher, respectively, than those of nonliposomal GL14711C (8.72 mg/kg). The comparative antitumor activity of SPI-355 and nonliposomal GL1472211C was evaluated in nude mice implanted with HT29 colon carcinoma xenografts. SPI-355 was 20-fold more effective than GL147211C in inhibiting tumor growth (1 mg/kg SPI-355 and 20 mg/kg GL147211C) and produced durable complete remissions of tumors at well-tolerated dose levels that were >5-fold lower than the maximally tolerated dose of GL147211C, which induced no durable complete responses. Signs of toxicity were similar between the two drugs, but liposome encapsulation increased the toxicity of drug approximately 4-fold, with increased weight loss and several deaths with SPI-355 (5 mg/kg SPI-355 versus 20 mg/kg GL147211C). Despite the increased toxicity seen with SPI-355, the therapeutic index of the liposomal formulation was increased approximately 5-fold over that of nonliposomal GL147211C, suggesting that such a pegylated liposomal formulation could demonstrate increased therapeutic index in human patients.

Animals↗
PubMed1997

Genetic and physical maps of Saccharomyces cerevisiae.

Genetic and physical maps for the 16 chromosomes of Saccharomyces cerevisiae are presented. The genetic map is the result of 40 years of genetic analysis. The physical map was produced from the results of an international systematic sequencing effort. The data for the maps are accessible electronically from the Saccharomyces Genome Database (SGD: http://genome-www.stanford. edu/Saccharomyces/).

Chromosome Mapping↗
PubMed1997

Demonstration of a peptide:N-glycosidase in the endoplasmic reticulum of rat liver.

Prompted by previous observations that polymannose oligosaccharides are released from newly synthesized glycoproteins [Anumula and Spiro (1983) J. Biol. Chem. 258, 15274-15282], we examined rat liver endoplasmic reticulum (ER) for the presence of endoglycosidases that could be involved in an event presumed to be a function of the protein quality control machinery. Our investigations indicated that a peptide:N-glycanase (PNGase) is present in ER membranes that has the capacity to release from radiolabelled glycopeptides glucosylated as well as non-glucosylated polymannose oligosaccharides terminating at their reducing end in a di-N-acetylchitobiose sequence (OS-GlcNAc2). This enzyme, which was found to be luminal in orientation, was most active in the pH range 5.5-7.0 and although it had no exogenous bivalent-cation requirements it was inhibited by EDTA. Detailed studies with Man9GlcNAc2-peptides demonstrated that in addition to the free oligosaccharide (Man9GlcNAc2) an additional neutral product characterized as Man9GlcNAc2 linked to an as yet unidentified aglycone was released in a manner that suggests its role as an intermediate. Our observation that ER, in contrast with cytosol, had no endo-beta-N-acetylglucosaminidase activity would indicate that oligosaccharides terminating in a single GlcNAc residue (OS-GlcNAc1), which have been noted to appear in the extravesicular compartment shortly after N-glycosylation [Moore and Spiro (1994) J. Biol. Chem. 269, 12715-12721] are released from the protein as OS-GlcNAc2 and undergo an ER-to-cytosol translocation in that form before undergoing cleavage of their chitobiose core.

Acetylglucosaminidase↗
PubMed1997

[Molfig, a software for displaying the structure and vibration of molecule].

A Molfig software has been developed for displaying the structure and vibrational mode of molecule in our lab. Various functions and a friendly interface are equipped in the software. The testing results showed that the software may enhance our understanding of the relationship between the vibrational behavior and the structure of molecules.

English Abstract↗
PubMed1997

[Curvefit, an overlapping bands resolving software for IR spectra].

A Curvefit software has been developed for resolving the overlapping band of the vibartional spectra in our lab . Various functions and a friendly interface are equipped in the software. The testing results showed that both the speed of the calculation and the reliability of the final results are satisfactory.

English Abstract↗
PubMed1996

Endoplasmic reticulum kifunensine-resistant alpha-mannosidase is enzymatically and immunologically related to the cytosolic alpha-mannosidase.

Studies were undertaken to evaluate the relationship of the recently described (S. Weng and R. G. Spiro, 1993, J. Biol. chem. 268, 25656-25663) rat liver kifunensine (KIF)-resistant mannosidase (ER mannosidase II) to the mannose-trimming enzyme of cytosol. We observed that the ER mannosidase II manifests a large number of catalytic and immunological properties similar to those of the cytosolic alpha-mannosidase, which contrast with the quite different characteristics of the KIF-sensitive enzyme (ER mannosidase I). In addition to a mutual resistance to KIF inhibition, the cytosolic enzyme and ER mannosidase II have comparable susceptibility to blocking by swainsonine and 1,4-dideoxy-1,4-imino-D-mannitol, and the latter agent was found to function effectively both in vitro and in vivo. The cytosolic and ER II mannosidases were alike in specifically excising the terminal mannose of the alpha 1,6-linked chain of Man9GlcNAc to yield Man8GlcNAc isomer C; in preferentially hydrolyzing polymannose-GlcNAc1 over polymannose-GlcNAc2 substrates; and in cleaving p-nitrophenyl alpha-D-mannoside. An immunological cross-reactivity between cytosolic mannosidase (M(r) 105 kDa) and ER mannosidase II (M(r) 82 kDa), neither of which is N-glycosylated, was established, suggesting that the latter is translocated posttranslationally into the lumen of the ER compartment in which we found it to be present as a soluble protein. Since antibodies directed against a sequence near the C-terminal end of the cytosolic enzyme reacted with ER mannosidase II while those against a sequence close to the N-terminus did not, it is likely that a proteolytic cleavage of the latter segment takes place during or after translocation. The absence in ER mannosidase II of the pronounced cobalt activation of the cytosolic enzyme suggests that the portion of the polypeptide chain removed during the 105- to 82-kDa conversion includes the binding domain for this ion.

Acetylglucosamine↗