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Biomedical subjects

W Lu

Publications and source records attributed to W Lu.

At least 289 records · Page 16Linked to original sources
PubMed1996

A ribonuclease-resistant method of in situ hybridization histochemistry in rat brain tissue.

Two major problems limiting neurobiological applications of in situ hybridization are: (1) contamination by ribonuclease (RNase), which is difficult to avoid and therefore makes the method difficult to establish for many laboratories, and (2) lack of reproducibility, which makes the method inadequate for detecting and quantifying changes in mRNA levels. We have developed a modified method of in situ hybridization which addresses these problems. RNase resistance is afforded by the inclusion of RNase inhibitors during steps in which mRNA is vulnerable to RNase digestion, alleviating the need to maintain RNase-free conditions during experiments. These changes result in higher levels of specific hybridization, while maintaining low background. In addition, a high level of reproducibility is obtained, both for sections obtained from the same animal and for corresponding sections obtained from different animals. This method has been characterized for preproenkephalin and glutamate receptor GluR 1-4 mRNAs.

Animals↗
PubMed1996

Genes expressed in Brugia malayi infective third stage larvae.

We have used a tag sequencing approach to survey genes expressed in the third stage infective larvae of the human filarial nematode parasite Brugia malayi. RNA was isolated from late vector-stage L3 larvae after days 9 or 10 of infection in mosquitos, and converted to cDNA by reverse transcriptase. Double-stranded cDNA was produced by either conventional methods (non-SL cDNA library) or by PCR using the nematode spliced leader (SLI) and oligo(dT) primers (SL cDNA library). Two clone libraries (one from SL and one from non-SL cDNAs) were constructed in lambda ZapII. A set of these full-length clones was selected and 596 inserts were sequenced from the 5' end. We have identified 364 B. malayi genes (the majority of which are new) that encode housekeeping proteins, structural proteins, proteins of immediate immunological or drug-discovery interest as well as a large class of novel sequences which may prove to have significant involvement in host invasion. Extensive, genome-wide approaches to the analysis of larval gene expression are now possible for B. malayi. We present several examples of this approach.

Amino Acid Sequence↗
PubMed1996

Absence of clinical, virological, and immunological signs of progression in HIV-1-infected patients receiving active anti-interferon-alpha immunization: a 30-month follow-up report.

Twenty-seven HIV-1-infected patients, 16 at early stage of disease and without concomitant antiretroviral therapy and 11 at more advanced stage of disease receiving antiretroviral therapy, have been followed since their enrollment, November 1992 and July 1993, respectively, in phase I/II studies to evaluate safety and immunogenicity of an anti-interferon-alpha (IFN-alpha) vaccine, aimed at modulating the impaired cytokine network in AIDS patients by counteracting IFN-alpha overproduction. We compared clinical, virological, and immunological markers of disease progression, including circulating IFN-alpha levels in a 24- to 30-month follow-up period with those of 62 patients fulfilling the same enrollment criteria and comparable for sex, risk factor, and age, regularly followed at our center. Anti-IFN-alpha immunization consisted of four-six intramuscular injections 1 month apart of a water-in-oil emulsion of 500 micrograms formalin-inactivated recombinant IFN-alpha-2b (iIFN-alpha) followed by intramuscular injections of 250 micrograms iIFN-alpha adsorbed onto calcium phosphate every 3 months. Neither clinical deterioration nor a CD4+ cell count decrease from pretreatment values was observed in IFN-alpha-immunized patients in the follow-up period, whereas clinical and immunological disease progressions were observed among open-comparison patients. Furthermore, statistical analysis showed a strong association between occurrence of clinical manifestations and high circulating IFN-alpha titers, while nonprogression of IFN-alpha-immunized patients was associated with decreased levels of circulating IFN-alpha.

Adolescent↗
PubMed1996

Interphase cytogenetics of workers exposed to benzene.

Fluorescence in situ hybridization (FISH) is a powerful new technique that allows numerical chromosome aberrations (aneuploidy) to be detected in interphase cells. In previous studies, FISH has been used to demonstrate that the benzene metabolites hydroquinone and 1,2,4-benzenetriol induce aneuploidy of chromosomes 7 and 9 in cultures of human cells. In the present study, we used an interphase FISH procedure to perform cytogenetic analyses on the blood cells of 43 workers exposed to benzene (median = 31 ppm, 8-hr time-weighted average) and 44 matched controls from Shanghai, China. High benzene exposure (> 31 ppm, n = 22) increased the hyperdiploid frequency of chromosome 9 (p < 0.01), but lower exposure (< or = 31 ppm, n = 21) did not. Trisomy 9 was the major form of benzene-induced hyperdiploidy. The level of hyperploidy in exposed workers correlated with their urinary phenol level (r = 0.58, p < 0.0001), a measure of internal benzene dose. A significant correlation was also found between hyperdiploidy and decreased absolute lymphocyte count, an indicator of benzene hematotoxicity, in the exposed group (r = -0.44, p = 0.003) but not in controls (r = -0.09, p = 0.58). These results show that high benzene exposure induces aneuploidy of chromosome 9 in nondiseased individuals, with trisomy being the most prevalent form. They further highlight the usefulness of interphase cytogenetics and FISH for the rapid and sensitive detection of aneuploidy in exposed human populations.

Adult↗
PubMed1996

An epidemiologic study of early biologic effects of benzene in Chinese workers.

Benzene is a recognized hematotoxin and leukemogen, but its mechanisms of action in humans are still uncertain. To provide insight into these processes, we carried out a cross-sectional study of 44 healthy workers currently exposed to benzene (median 8-hr time-weighted average; 31 ppm), and unexposed controls in Shanghai, China. Here we provide an overview of the study results on peripheral blood cells levels and somatic cell mutation frequency measured by the glycophorin A (GPA) gene loss assay and report on peripheral cytokine levels. All peripheral blood cells levels (i.e., total white blood cells, absolute lymphocyte count, platelets, red blood cells, and hemoglobin) were decreased among exposed workers compared to controls, with the exception of the red blood cell mean corpuscular volume, which was higher among exposed subjects. In contrast, peripheral cytokine levels (interleukin-3, interleukin-6, erythropoietin, granulocyte colony-stimulating factor, tissue necrosis factor-alpha) in a subset of the most highly exposed workers (n = 11) were similar to values in controls (n = 11), suggesting that benzene does not affect these growth factor levels in peripheral blood. The GPA assay measures stem cell or precursor erythroid cell mutations expressed in peripheral red blood cells of MN heterozygous subjects, identifying NN variants, which result from loss of the GPA M allele and duplication of the N allele, and N phi variants, which arise from gene inactivation. The NN (but not N phi) GPA variant cell frequency was elevated in the exposed workers compared with controls (mean +/- SD, 13.9 +/- 8.4 mutants per million cells versus 7.4 +/- 5.2 per million cells, (respectively; p = 0.0002), suggesting that benzene produces gene-duplicating but not gene-inactivating mutations at the GPA locus in bone marrow cells of exposed humans. These findings, combined with ongoing analyses of benzene macromolecular adducts and chromosomal aberrations, will provide an opportunity to comprehensively evaluate a wide range of early biologic effects associated with benzene exposure in humans.

Adult↗
PubMed1996

[Clinical and experimental study of RA mixture in treatment of rheumatoid arthritis].

The RA mixture is composed of Tripterygium Wilfordii (TW) and other Chinese medicinal herbs with effect of expelling Wind, activiting blood circulation, invigorating the Kidney and Qi. The authors treated rheumatoid arthritis (RA) patients with RA mixture and compared it with D-penicillamine as control. The two group's therapeutical effect is similar (P > 0.05), but the side effect occuring ratio in treatment group was obviously lower than that of control group (P < 0.01). After treatment with RA mixture, the patient's human lymphocytic antigen-degenerative reaction (HLA-DR+) cell, CD4/CD8 ratio reduced and auto-mixed lymphocytic reaction (AMLR) level enhanced (P < 0.05). The results of animal experiment showed that swelling of RA model mouse's joint could be reduced by both RA mixture and TW. Comparing with TW, RA mixture had stronger effect in controlling the inflammation of synovial cell and fibroid degeneration of fibrocytes. At the same time, RA mixture had stronger effect in protecting the immune organ from atrophy and protecting functions of cellular immunity. All above suggest that RA mixture reduce the syndroms of RA by improving distribution of T lymphocyte subsets and the functions of cellular immunity. The other Chinese medicinal herbs in the RA mixture could enhance TW's therapeutical effect and reduce it's side effect.

Adult↗
PubMed1996

[Canonical correlation of body composition and pulmonary function in children aged eight to twelve].

Canonical correlation of body composition and pulmonary ventilation function in school boys and girls aged 8 to 12 and normally developed was analyzed. Skinfolds of triceps and subscapular angle were measured, and body composition was estimated as body fat percentage (BF%), body fat (BF) and lean body mass (LBM). Ventilation function was measured. Results indicated that correlation between body composition and ventilation function mainly attributed to a positive correlation between LBM and vital capacity (VC) and a negative correlation between BF% and a ratio of expiratory reserve volume (ERV) to VC. It suggests effects of body composition on ventilation function mainly attributed to LBM and BF%.

Body Composition↗
PubMed1996

[Determination of visual function after implantation of intraocular lens].

OBJECTIVE: To understand whether the binocular visual function could be restored after posterior chamber intraocular lens (IOL) implantation. METHODS: The visual function including corrected vision, simultaneous perception, fusion, stereoacuity, aniseikonia and retinal correspondence point were determined for 50 cases (64 eyes) after the surgery. RESULTS: The corrected visual acuities were 0.6 or better. Visual acuities of 1.0 or better were achieved in 65% and 0.6-0.9 in 35% of the eyes. All patients obtained simultaneous perception and fusion function. The near stereoacuity of 50 cases showed foveal stereoacuity < or = 60 seconds in 23 cases (46%), macular stereoacuity 80-200 seconds 10 cases (20%) and peripheral stereoacuity 400 seconds 17 cases (34%). The far stereoacuity of 50 cases comprised 34 cases of foveal stereoacuity (68%), 9 cases of macular stereoacuity (18%) and 7 cases of peripheral stereoacuity (14%). The postoperative retinal correspondence points were normal. There was no aniseikonia in 35 cases, except 15 cases of aniseikonia which was within normal tolerable limits. CONCLUSION: When binocular corrected vision is > or = 0.4 with ocular alignment, the binocular visual function could be restored for varying degrees.

Adolescent↗
PubMed1996

[The value of dynamic pulmonary perfusion imaging in the diagnosis of hepatopulmonary syndrome (HPS)].

OBJECTIVE: To evaluate the value of 99m-Tc-MAA dynamic pulmonary perfusion imaging in the diagnosis of HPS. METHODS: 3 cases of liver cirrhosis with marked hypoxemia were studied. RESULTS: The shunt ratios with 100% inspired oxygen were elevated (16%, 27% and 11% respectively). Imaging with gamma camera revealed radioisotope uptake in their lungs, brains and kidneys. Shunt ratios estimated by the quantitative radionuclide method were 43%, 52% and 32% respectively). (control < 7%). The contradictory shunt ratio by using the above method results from dilation of alveolar capilaries. The same examinations were done in 10 cases of healthy controls and other patients. CONCLUSION: The imaging helps diagnosing the HPS as well as estimating the degree of shunting.

Adult↗
PubMed1995

Subsets of midbrain dopaminergic neurons in monkeys are distinguished by different levels of mRNA for the dopamine transporter: comparison with the mRNA for the D2 receptor, tyrosine hydroxylase and calbindin immunoreactivity.

The midbrain dopamine system can be divided into two groups of cells based on chemical characteristics and connectivity. The dorsal tier neurons, which include the dorsal pars compacta and the ventral tegmental area, are calbindin-positive, and project to the shell of the nucleus accumbens. The ventral tier neurons are calbindin-negative and project to the sensorimotor striatum. This study examined the distribution of the mRNAs for the dopamine transporter molecule (DAT) and the D2 receptor in the midbrain of monkeys by using in situ hybridization. The distribution patterns were compared to that of tyrosine hydroxylase and calbindin immunohistochemistry. The results show that high levels of hybridization for DAT and the D2 receptor mRNA are found in the ventral tier, calbindin-negative neurons and relatively low levels are found in the dorsal, calbindin-positive tier. Within the dorsal tier, the dorsal substantia nigra pars compacta has the least amount of both messages. These results show that in monkeys, the ventral tegmental area and the dorsal pars compacta form a dorsal continuum of dopamine neurons which express lower levels of mRNA for DAT and D2 receptor than the ventral tier. DAT has been shown to be involved in the selective neurotoxicity of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Different levels of DAT mRNA and calbindin may explain the differential effects of MPTP neurotoxicity.

Animals↗
PubMed1995

On-line high-performance liquid chromatography-electrospray ionization mass spectrometry for the determination of brevetoxins in "red tide" algae.

On-line high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESMS) has been successfully applied to the separation and identification of brevetoxins associated with "red tide" algae. Brevetoxins are toxic polyethers produced by the marine dinoflagellate Gymnodinium breve. They are responsible for fish kills, and they pose certain health risks to humans. The LC-MS method employs reversed-phase microbore HPLC on a C18 column with a mobile phase consisting of 85:15 methanol/water, a flow rate of 8 microL/min, and a postcolumn split ratio of 3:1 (UV absorbance detector/mass spectrometer). A brevetoxin culture sample was found to contain at least six components, including two well-separated peaks corresponding to the brevetoxins PbTx-2 and PbTx-1, as well as several unknown compounds, including one with a molecular mass of 899 Da (possibly an isomer of PbTx-9). The brevetoxin molecules exhibited a high tendency to bind to alkali cations in positive ion ESMS. For standard PbTx-9, PbTx-2, and PbTx-1 brevetoxins analyzed on our LC-MS system, the detection limits (employing mass spectrometer scans of 100 m/z units) were determined to be less than 600 fmol, 1 pmol, and 50 fmol, respectively (S/N = 3); the total analysis time was about 35 min.

Animals↗
PubMed1995

Determination of amino acids by on-line capillary electrophoresis-electrospray ionization mass spectrometry.

On-line capillary electrophoresis-electrospray ionization mass spectrometry (CE-ESMS) has been used for the separation and detection of amino acid mixtures. Four natural amino acids, histidine, tryptophan, phenylalanine, aspartic acid, and a tripeptide, glutathione, were separated and determined. Protonated molecules were detected in the CE-ESMS mode with detection limits of about one pmol. Optimum CE-ESMS operating conditions for amino acid analysis were determined employing acetic acid solutions as CE electrolytes. The examined parameters included capillary diameter (50-100 microns internal diameter), applied separation voltage (20-30 kV), and concentration of electrolyte (10-60% acetic acid). Stable working conditions were maintained when the CE currents were less than 18 microA. The use of electrolyte solutions such as those described here instead of true buffer solutions may have advantages for CE-ESMS systems which employ a "sheathless" interface.

Amino Acids↗
PubMed1995

Water molecules participate in proteinase-inhibitor interactions: crystal structures of Leu18, Ala18, and Gly18 variants of turkey ovomucoid inhibitor third domain complexed with Streptomyces griseus proteinase B.

Crystal structures of the complexes of Streptomyces griseus proteinase B (SGPB) with three P1 variants of turkey ovomucoid inhibitor third domain (OMTKY3), Leu18, Ala18, and Gly18, have been determined and refined to high resolution. Comparisons among these structures and of each with native, uncomplexed SGPB reveal that each complex features a unique solvent structure in the S1 binding pocket. The number and relative positions of water molecules bound in the S1 binding pocket vary according to the size of the side chain of the P1 residue. Water molecules in the S1 binding pocket of SGPB are redistributed in response to the complex formation, probably to optimize hydrogen bonds between the enzyme and the inhibitor. There are extensive water-mediated hydrogen bonds in the interfaces of the complexes. In all complexes, Asn 36 of OMTKY3 participates in forming hydrogen bonds, via water molecules, with residues lining the S1 binding pocket of SGPB. For a homologous series of aliphatic straight side chains, Gly18, Ala18, Abu18, Ape18, and Ahp18 variants, the binding free energy is a linear function of the hydrophobic surface area buried in the interface of the corresponding complexes. The resulting constant of proportionality is 34.1 cal mol-1 A-2. These structures confirm that the binding of OMTKY3 to the preformed S1 pocket in SGPB involves no substantial structural disturbances that commonly occur in the site-directed mutagenesis studies of interior residues in other proteins, thus providing one of the most reliable assessments of the contribution of the hydrophobic effect to protein-complex stability.

Alanine↗