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Biomedical subjects

M Wu

Publications and source records attributed to M Wu.

At least 415 records · Page 23Linked to original sources
PubMed1994

[Study on unit discharges of the posterior group of thalamic nuclei evoked by electric stimulation of centromedian nucleus in cat].

The unit discharges of posterior group of thalamic nuclei (PO), evoked by stimulating greater splanchnic nerve (SPL) and centromedian nucleus (CM) respectively in cats were studied with extracellular recording method and stereotaxic techniques. The evoked potentials of 63 neurons in PO by stimulating SPL and 16 ones in PO by stimulating CM were observed in 26 cats, indicating that PO might be one of the representative areas of the splanchnic afferent pathway and there might be a nervous projection between CM and PO. Moreover, convergence of unit discharges produced by stimulating CM and SPL in PO was found, suggesting that pain signals from the viscera and impulses from CM can interact each other at PO.

Animals↗
PubMed1994

[The distribution of gene frequencies of immunoglobulin allotype G2m(23) factor in Chinese populations].

The distribution of G2m(23) gene frequencies in eight Chinese populations, which cover three ethnic groups, was studied by enzyme linked immunosorbent assay inhibition test. According to the results of multiple linear regression and multiple liner correlation there exists a cline of G2m(23) gene frequencies along with the height and latitude in China. In addition, an equation of multiple linear regression which can be used to expect the G2m(23) gene frequencies in some Chinese populations was established. Some possible reasons for this cline were also discussed.

Asian People↗
PubMed1994

[Influence exerted by environmental and physicochemical factors on the results of sex identification of human dental pulp by polymerase chain reaction].

Sex identification of human tooth is an important aspect of individual identification in forensic science practice. This study was designed to determine the effects of environmental and physicochemical factors (EPF) on the deoxyribonucleic acid (DNA) from dental pulp and PCR result. Extracted teeth were subjected to the following treatment varying pH (2, 7, 10) solution; 10% formalin, 75% ethanol; different temperature (-20 degrees C, 4 degrees C, 25 degrees C, 37 degrees C, boiling, burning); humidity (20%, 66%, water submergence); burying the teeth outdoors; and aging (teeth stored at room temperature for 1.5, 3.5 and 8 years). DNA was extracted from the tooth followed by agarose gel electrophoresis for the purpose of DNA assay and quantity determination. Amplification was carried out using a pairs of primer Y1.1 and Y1.2. The results of the study showed that, 154 bp fragment was obtained in all male teeth, whereas no 154 bp fragment was found in a female fresh tooth. 154 bp fragment bands were not observed in case of teeth subjected to burial outdoors for 10 weeks, submergence in water for 10 weeks, soak in pH 2 solution for 10 weeks, and combustion for 10 minutes; only faint bands were observed in case of teeth subjected to 66% humidity and pH 10 solution for 10 weeks and combustion for 5 minutes; obvious bands were observed in the rest cases. In addition, the quality of DNA from dental pulp affected PCR amplification result. The integrity of DNA isolated was categorized as being high-molecular-weight (HMW), HMW with partial degraded DNA, completely degraded DNA, completely degraded and not detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1994

Social functioning and overall mortality: prospective evidence from the Kuopio Ischemic Heart Disease Risk Factor Study.

We studied the associations between 11 scales of social functioning and risk of death over an average follow-up time of 71 months in 42- to 60-year-old men in the Kuopio Ischemic Heart Disease Risk Factor Study. In age-adjusted analyses, men were at increased risk of death if they reported few persons to whom they gave or received social support, nonparticipation in organizations, low quality of social relationships, a small number of friends, or not currently being married. Frequency of interaction, shyness, and use of emotional support when troubled were not associated with risk of death; the use of instrumental support when troubled was associated with increased risk. There was little evidence of confounding of these associations by the presence of 31 chronic or acute conditions, perceived health status, or six risk factors. Consistent associations were found in a healthy subgroup. These data add to the growing body of literature linking mortality risk with social functioning, especially in relation to organizational participation and quality of relationships.

Adult↗
PubMed1994

[Application of ORM1 phenotyping in forensic science].

ORM1 is an important genetic marker for both parentage testing and personal identification in forensic science. We have examined the ORM1 phenotypes in the human serum and dried bloodstains using the ULPAGIF method. ORM1 phenotypes were successfully demonstrated from dried bloodstains stored at 4 degrees C and room temperature for up to twenty-four weeks. In bloodstains stored at 37 degrees C, the 100% of ORM1 phenotyping was no longer possible after 12 weeks. We examined 9 bloodstains stored at room temperature for one, two and three years, respectively. For the one-year-old bloodstains, all of the samples could be phenotyped correctly, for the two-year-old bloodstains 8 out of the 9 and for the three-year-old bloodstains 7 out of the 9 samples could be phenotyped correctly. The results have indicated that ORM1 is relatively stable, for it is tolerable toward high temperature and long duration. It was suggested that the bloodstains should be ultrasonicated before ULPAGIF, because the ultrasonication could elevate the detectable rate of ORM1 phenotypes from bloodstains. ORM1 phenotypes was performed in five disputed parentage cases. One of the alleged fathers was excluded.

Blood Stains↗
PubMed1994

[Studies on the induction of L-phenylalanine ammonia lyase(PAL) in Rhodotorula glutinis and transformation of phenylalanine from trans-cinnamic acid].

The induction of PAL in Rhodotorula glutinis and transformation of L-phenylalanine from trans-cinnamic acid were studied. The optimum medium for PAL induction was composed of (g/L) 10.0 yeast extract, 10.0 peptone, 5.0 NaCl, 0.5 KH2 PO4, 0.5 phenylalanine 1.0 (NH4)2SO4 and 5.0 glucose, pH 6.0-6.5. The cultivation temperature was 30.0 degrees C. In the process of transformation, the effect of [NH4]+ on initial velocity was in accordance with Michaelis-Menten rate expression in which Km and Vmax were 16.85 mol/L and 5.96 g.L-1.h-1 for ammonia and the optimum pH was 10.0. Substrate activation and inhibition were observed at low and high concentration of cinnamic acid. The yield of phenylalanine from cinnamic acid reached more than 60.0%.

Cinnamates↗
PubMed1993

Clonal growth and origin of two human keratinocyte cell lines transformed by human papillomavirus type 16 DNA.

Two human keratinocyte cell lines transformed by human papillomavirus type 16, designated Vp and Up, were compared for their clonal growth potential and clonal origin. Up showed greater anchorage-independent growth in soft agar and higher efficiency of single-cell colony formation than Vp (24.3% compared to approximately 10%). The clonal growth potential of these two cell lines was not related to the level of HPV16 gene expression. Fourteen single cell clones of the Vp and 24 of the Up were selected, propagated and analyzed by Southern and Northern blot analysis. Clonal variations existed among subclones of each cell line and between the two cell lines. These variations included cell morphology, growth potential, and expression levels of involucrin (a differentiation marker of keratinocytes) and of HPV16 mRNAs. The Vp and Up cell lines also showed different patterns of HPV16-DNA integration and RNA transcription. However, all subclones of Vp and subclones of Up displayed identical HPV16 DNA integration and RNA expression patterns. The results suggest that both cell lines were monoclonal in origin and that the host genetic factors play an essential role in determining cell clonality.

Cell Differentiation↗
PubMed1993

Lithium phthalocyanine: a probe for electron paramagnetic resonance oximetry in viable biological systems.

Lithium phthalocyanine (LiPc) is a prototype of another generation of synthetic, metallic-organic, paramagnetic crystallites that appear very useful for in vitro and in vivo electron paramagnetic resonance oximetry. The peak-to-peak line width of the electron paramagnetic resonance spectrum of LiPc is a linear function of the partial pressure of oxygen (pO2); this linear relation is independent of the medium surrounding the LiPc. It has an extremely exchange-narrowed spectrum (peak-to-peak line width = 14 mG in the absence of O2). Physicochemically LiPc is very stable; its response to pO2 does not change with conditions and environments (e.g., pH, temperature, redox conditions) likely to occur in viable biological systems. These characteristics provide the sensitivity, accuracy, and range to measure physiologically and pathologically pertinent O2 tensions (0.1-50 mmHg; 1 mmHg = 133 Pa). The application of LiPc in biological systems is demonstrated in measurements of pO2 in vivo in the heart, brain, and kidney of rats.

Animals↗
PubMed1993

Neurons in the inferior colliculus, auditory cortex and pontine nuclei of the FM bat, Eptesicus fucus respond to pulse repetition rate differently.

Single-neuron responses to pulse repetition rate in the inferior colliculus, auditory cortex and pontine nuclei of the FM bat, Eptesicus fuscus were studied under free-field stimulation conditions. The best frequency (BF) and minimum threshold (MT) of each neuron were first determined with a 4 ms pulse broadcast from a specific point (response center) of the bat's frontal auditory space at which the neuron had maximal spatial sensitivity. The neuron's intensity-rate function was then studied with a 4 ms BF pulse delivered at 10 dB increments above its MT in order to determine the best intensity to which the neuron discharged maximally. The neuron's discharge pattern and number of impulses to 32 trials of 300 ms train stimuli, which consisted of different number of 4 ms BF and best intensity pulses (1, 2, 3, 8, 12, 19, 24, 29 pulses/train) and delivered at an interpulse interval of 1000, 250, 170, 100, 40, 25, 15, 12 and 10 ms (i.e. at a pulse repetition rate of 1, 4, 6, 10, 25, 40, 67, 83, 100 pulses/s), were sequentially recorded. All neurons recorded from the inferior colliculus, auditory cortex and pontine nuclei discharged phasically (1-3 impulses) but they responded to the pulse repetition rate in different manners. More than 63% of 38 inferior collicular and 65 pontine neurons studied discharged impulses to each pulse within a train stimulus when the pulse repetition rate was up to 40 pulses/s.(ABSTRACT TRUNCATED AT 250 WORDS)

Acoustic Stimulation↗
PubMed1993

Inhibition of a reductive function of the plasma membrane by bacitracin and antibodies against protein disulfide-isomerase.

Evidence had been provided that a disulfide-linked [125I]iodotyramine/poly(D-lysine) conjugate was reductively cleaved when bound nonspecifically to the surface of Chinese hamster ovary (CHO) cells and that this cleavage was abolished by membrane-impermeant sulfhydryl blockers. The same blockers were subsequently found to inhibit the cytotoxicity of diphtheria toxin, a disulfide-linked heterodimer that binds to a specific surface receptor and must undergo chain separation to exert its cytotoxicity. This suggested that the disulfides of both macromolecules might be cleaved by a thiol-disulfide interchange reaction, possibly mediated by protein disulfide-isomerase (PDI, EC 5.3.4.1). We tested whether inhibitors of PDI--in particular, bacitracin and anti-PDI antibodies--might mimic the two effects of sulfhydryl blockers. Both bacitracin and anti-PDI antibodies were effective in inhibiting both reductive processes. This strongly suggests that the disulfide cleavage in the two membrane-bound macromolecules is mediated by PDI and that this enzyme, besides its known retention in the endoplasmic reticulum, must also be exposed at the plasma membrane. This paper points to other potentially important disulfide reductions that might be catalyzed by surface-associated PDI. It thereby broadens the known functions of an enzyme already known for its multifunctional properties.

4-Chloromercuribenzenesulfonate↗
PubMed1993

Human recombinant interleukin-1 beta up-regulates elastin gene expression in dermal fibroblasts. Evidence for transcriptional regulation in vitro and in vivo.

The effects of human recombinant interleukin (IL)-1 beta on elastin gene expression were studied in human skin fibroblast cultures by Northern hybridization and transient transfection experiments. Incubation of the cells with IL-1 beta elevated the elastin mRNA steady-state levels by approximately 3- to 4-fold. A similar increase was noted at the protein level, when estimated by indirect immunofluorescence of cultured cells. This effect was independent of the on-going protein synthesis, as tested by incubation with cycloheximide. Transient transfections of the dermal fibroblasts with a human elastin promoter/chloramphenicol acetyltransferase (CAT) reporter gene construct suggested transcriptional regulation, since the CAT activity in cells incubated with IL-1 beta was similarly increased approximately 3-fold. Enhancement of the human elastin promoter activity by IL-1 beta was also noted in fibroblast cultures established from the skin and lungs of transgenic mice which have integrated the human promoter/CAT construct into their genome and express it in a tissue-specific manner. Furthermore, subcutaneous injection of IL-1 beta to the mice resulted in a approximately 4-fold elevation of the CAT activity in the skin after a 30-h incubation, as compared to the CAT activity in the skin of control animals. Collectively, these data indicate that IL-1 beta up-regulates elastin gene expression in fibroblast cultures as well as in the skin in vivo, and the activation occurs at the transcriptional level.

Animals↗
PubMed1993

Spinach thioredoxin m inhibits DNA synthesis in fertilized Xenopus eggs.

A role for thioredoxin in metazoan DNA synthesis has been assessed by injecting rapidly dividing Xenopus eggs with purified heterologous thioredoxins, which might act as inhibitors if they were to replace resident thioredoxins in some but not all reaction steps. Of 10 tested proteins, spinach chloroplast thioredoxin m is the most potent inhibitor. Eggs cleave and produce cells lacking nuclei. DNA synthesis is severely reduced. Development arrests before gastrulation. In egg extracts, thioredoxin m inhibits incorporation of radioactive dCTP into DNA of sperm nuclei and M13 phage. Inhibition exceeds 90% when thioredoxin m and M13 DNA are preincubated together. The data support the interpretation that thioredoxins normally participate in initiation of metazoan DNA synthesis.

Animals↗