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Biomedical subjects

W Wu

Publications and source records attributed to W Wu.

At least 397 records · Page 22Linked to original sources
PubMed1995

[An epidemiological study on reproductive effects in female workers exposed to acrylonitrile].

Four hundred and seventy-seven female workers exposed to acrylonitrile and 527 controls were studied by retrospective cohort method. Results showed incidence rates of pernicious vomiting and anemia, preterm delivery, and birth defects in exposed women were obviously higher than those in controls, with statistical significance. Logistic regression analysis revealed exposure to acrylonitrile in pregnant workers caused increasing risk of preterm delivery and birth defects. In addition, illness, medicine taking and X-ray irradiation during pregnancy related to the increase of incidence of preterm delivery in exposed women.

Acrylonitrile↗
PubMed1995

MR imaging of 495 consecutive cases with sensorineural hearing loss.

PURPOSE: To examine patients with sensorineural hearing loss (SNHL) with MR. MATERIAL AND METHODS: 495 consecutive patients with SNHL and 120 age-matched healthy controls were examined. Spin-echo (SE) and fast spin-echo (FSE) images were used with 1.5 T equipment. RESULTS: An intracranial abnormality was found in 211 (42.6%) of the patients with 95 (19.2%) along the acoustic pathway. Eleven of the 95 patients had sensory hearing loss while 84 had neural hearing loss with the retrocochlear auditory pathway affected by lesions. In 62 of the 84 patients, the internal acoustic canal and cerebellopontine angle were involved. Twenty-two patients had intra-axial lesions. The controls had no pathologic changes along the auditory pathway. CONCLUSION: MR imaging in a patient with SNHL must cover the entire acoustic pathway from the cochlea to the superior temporal gyrus, and all the components of the auditory pathway should be scrutinized. The FSE-technique can be used to detect the lesions causing SNHL. FSE-sequences can replace SE-sequences.

Adolescent↗
PubMed1995

[Studies on mode of human infection with Echinochasmus liliputanus].

Epidemiological survey and experimental studies on the mode of human infection with Echinochasmus liliputanus were carried out in Chenqiaozhou Village, Hexian County, Anhui Province in 1992. The results showed that humans could be infected through drinking unboiled water containing E.liliputanus cercaria or eating raw fish containing the metacercaria. The infection rates of E. liliputanus were 1.5% in the inhabitants who did not drink raw water, and 20.1% in those who used to drink raw water. It was only the cercaria, not the metacercaria that was detected in the water from ponds of this village. None of the investigated inhabitants ate uncooked fish. The results indicated that drinking raw water containing E.liliputanus cercaria was a major way through which a humans were infected and eating food containing the metacercaria was a minor mode of human infection.

Animals↗
PubMed1995

Effects of Panax notoginseng saponin Rg1 on cardiac electrophysiological properties and ventricular fibrillation threshold in dogs.

AIM: To study the effects of Rg1 isolated from saponins of Panax notoginseng on cardiac electrophysiological properties and ventricular fibrillation threshold (VFT). METHODS: Seventeen open-chest dogs were randomly allocated into a Rg1 group (20 mg kg-1, iv) and a control group. The electrophysiological variables and VFT were evaluated by standard electric stimuli and monophasic action potential (MAP) recording. RESULTS: Rg1 prolonged sinus node recovery time (SNRT) by 19.1%, AV conduction Wenckebach cycle length (AVWCL) by 7.1%, and ventricular effective refractory period (VERP) by 7.9%. It prolonged ventricular MAPD30, MAPD50, and MAPD90 by 25.5%, 24.2%, and 13.5%, respectively. VFT was increased by 19.2%. CONCLUSION: Rg1 prolonged ventricular refractoriness and repolarization, and increased VFT. It was indicated that cardiac electrophysiological effects of Rg1 were similar to those of amiodarone.

Action Potentials↗
PubMed1995

[The diagnosis and surgical management of parathyroid cysts].

Six cases of parathyroid cysts were treated in our hospital during a ten--year period with an incidence of 0.27% of the total patients operated on for neck mass. Four females and two males had an average age of 47.5 years with a history of the disease from 3 monts to 30 years. All patients had a single cyst ranging in size from 2.7 to 7.0 cm in diameter, arising in the region of inferior parathyroid gladms. Five caese of asymptomatic neck mass were nonfunctioning cysts, which where thin--walled and contained clear watery fluid. One case associated with hyperparathyroidism was classified as functioning cyst confirmed histologically as parathyroid adenoma with intracapsular hemorrhage. Surgical excision was made in all cases and postoperative recovery was uneventful. The importance of imaging studies, percutaneous biopsy, and cyst fluid assay for PTH in preoperative diagnosis was emphasized.

Adenoma↗
PubMed1995

[In vitro experiment on scavenging oxy-radical and suppressing myocardial lipid peroxidation with sini decoction].

Results indicate that Sini Decoction has a significant effect of anti-lipid peroxidation of its components, Radix Aconiti Preparata and Radix Glycyrrhizae can significantly suppress lipid peroxidation of myocardial homogenate, while Rhizoma Zingiberis cannot. The decoction can effectively scavenge oxygen free radicals, each component having similar effect to some extent.

Animals↗
PubMed1994

Characterization of an RNase H deficient mutant of human immunodeficiency virus-1 reverse transcriptase having an aspartate to asparagine change at position 498.

It has been proposed that Asp-443, Glu-478, and Asp-498 are important in RNase H mediated catalysis by human immunodeficiency virus-1 reverse transcriptase (Davies J.F., Hostomska, Z. Hostomsky, Z., Jordan, S.R. and Matthews, D.A. (1991) Science 251, 88-95; Mizrahi, V., Usdin, M.T., Harington, A. and Dudding, L.R. (1990) Nucleic Acids Res. 18, 5359-5363). Single point mutations at either position 443 (Mizrahi, V., Usdin, M.T., Harington, A. and Dudding, L.R. (1990) Nucleic Acids Res. 18, 5359-5363) or 478 (Schatz, O., Cromme, F.V., Grüninger-Leitch, F. and Le Grice, S.F.J. (1989) FEBS Lett. 257, 311-314) severely inhibit RNase H activity but have only small effects on polymerase activity. We show here that a single mutation at position 498 of Asp to Asn (mutant D498N) results in a stable enzyme with a 20-fold reduction in the ratio of RNase H to polymerase activity. The mutant and wild type enzymes were equally processive, paused in the same locations, and extended primers at the same rate during DNA synthesis on a heteropolymeric RNA template. The rate of elongation on the homopolymeric template poly(rA) was also the same. The results indicate that the mutation does not affect normally measured catalytic parameters of the polymerase function of the enzyme. D498N catalyzed strand transfer synthesis on homopolymeric, but not heteropolymeric templates, indicating that RNase H activity is not required for the former activity, but is for the latter.

Asparagine↗
PubMed1994

Expression of c-jun and neuronal nitric oxide synthase in rat spinal motoneurons following axonal injury.

Expression of neuronal NOS, c-jun and c-fos in spinal motoneurons following axonal damage were investigated in the present study. Although either distal spinal root axotomy or root avulsion induced expression of c-jun, expression of c-jun was predominantly found in distal root-axotomized motoneurons. In contrast, expression of NOS was exclusively observed in avulsed motoneurons. c-fos was not expressed in spinal motoneurons following either distal root axotomy or root avulsion. The different expression patterns of c-jun and NOS in the injured neurons suggest that these molecules may involve in different cellular processes and might play different roles in response to the injury. Since distal root axotomy did not cause motoneuron death and root avulsion did, expression of c-jun is likely related to regenerative process while induction of NOS may be involved in the degenerative process.

Amino Acid Oxidoreductases↗
PubMed1994

Demonstration of a double-stranded DNA-stimulated protein kinase (DNA-PK) inhibitory activity in human HL-60 leukemia cells.

A 41,000 protein, p41, was highly purified from human promyelocytic HL-60 cells by chromatography on GTP-agarose columns. The purified p41 inhibited phosphorylation of endogenous substrates present in partially purified DNA-PK from HL-60 or HeLa cells, as well as phosphorylation of recombinant protein tau mediated by the purified HeLa DNA-PK. The ability of p41 to inhibit DNA-PK was largely abolished by heating at 95 degrees C for 30 min.

Chromatography, Affinity↗
PubMed1994

Transgenic mice expressing human lipoprotein lipase driven by the mouse metallothionein promoter. A phenotype associated with increased perinatal mortality and reduced plasma very low density lipoprotein of normal size.

We have produced transgenic mice expressing human lipoprotein lipase (LPL) driven by the mouse metallothionein I promoter. We found that integration of the LPL gene construct was associated with a high perinatal mortality. Animals that survived the first 2 weeks of life grew normally afterwards. Compared with controls, transgenic animals had higher post-heparin plasma LPL and tissue LPL activities. Immunoreactive human LPL was detected in their post-heparin plasma but not in controls. Transgenic animals had significantly lower plasma very low density lipoprotein (VLDL) while on a regular laboratory chow. By electron microscopic analysis and nondenaturing polyacrylamide gradient gel electrophoresis, the size and morphology of the plasma VLDL were very similar in transgenic and control animals, which suggests that VLDL particles acted on by the increased tissue LPL in the transgenic animals were mostly taken up by the cell without being released back into circulation. The hypertriglyceridemia and elevated VLDL in response to sucrose feeding were completely abolished in transgenic animals. They also had lower VLDL lipids compared with control animals when they were fed a high-fat, high-cholesterol diet. Feeding the mother of transgenic mice a high-fat diet during pregnancy completely reversed the high perinatal mortality associated with the integrated transgene, which suggests that the deleterious effect of LPL overexpression may be related to the depletion of some essential lipid nutrient.

Animals↗
PubMed1994

Two distinct types of cardiotoxin as revealed by the structure and activity relationship of their interaction with zwitterionic phospholipid dispersions.

Cardiotoxins (CTXs) are a group of homologous proteins found in cobra snake venom and consist of 60-62 amino acid residues. Although CTXs are known to consist of three extended beta-sheet loops similar to neurotoxins, the target and interaction of CTXs with membranes unlike those of neurotoxins are not well understood. Herein, we report comparative studies of 10 CTXs purified from Taiwan cobra (Naja naja atra) and Mozambique spitting cobra (Naja mossambica mossambica) snake venoms with respect to their interactions with zwitterionic phospholipids. Based on the CTX-induced mixing of sphingomyelin vesicles and the binding of CTX to lysophosphatidylcholine micelles, two distinct types of CTX, i.e. P- and S-type CTX, are identified. P-type CTXs are characterized by the presence of Pro-31 within a putative phospholipid binding site near the tip of loop 2; whereas S-type CTXs are characterized by the presence of Ser-29 within the same but more hydrophilic region. Although binding of all CTXs to phospholipid membranes involves a phospholipid binding site at loop 1, P-type CTXs exhibit higher fusion and binding activity than S-type CTXs, presumably due to the additional phospholipid binding site at loop 2. The binding modes of P- and S-type CTX are thus different. Analysis of the primary structures of 46 CTXs from the genus Naja indicates that these two types of CTXs exist in all species examined. Reasonable structure/activity correlation can be detected for the effects of CTXs on muscle and red blood cells, although notable exceptions are also found. S-type CTXs are generally found to exhibit higher muscle cell depolarization activity, whereas P-type CTXs are found to possess a higher hemolytic activity. Thus the mechanism of action of CTXs seems to involve CTX-membrane interactions and depends on the type of the cell membrane and CTX molecules under study. The two lipid binding sites in P-type CTXs and one lipid binding site in S-type CTXs show large variation in their amino acid residues, but they do display some common distribution of residue type. Analogous to the signal sequences for protein import, these regions are characterized by the coexistence of an exposed hydrophobic surface flanked on either side by a cationic residue. A hypothesis is proposed to explain the general cytotoxic and specific cardiotoxic effect of CTXs based on the two CTX subtypes in snake venom.

Amino Acid Sequence↗
PubMed1994

High-molecular-weight polypeptide substrates for phospholysine phosphatases.

The detection and characterization of the phosphatases responsible for the dephosphorylation of N-phosphoryl groups, such as phospholysine, in proteins has been frustrated in large measure by a lack of suitable substrates for the assay of these enzymes. Herein we describe the preparation of phospholysine-containing amino acid homo- and heteropolymers by chemical means, and their use in a simple, nonradioactive assay for phospholysine phosphatase activity.

Acid Phosphatase↗