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Biomedical subjects

Y Qi

Publications and source records attributed to Y Qi.

15 recordsLinked to original sources
PubMed1992

Mortality and incidence of bladder cancer in benzidine-exposed workers in China.

We examined bladder cancer mortality and incidence to 1981 in 1,972 workers employed in benzidine-exposed jobs in Tianjin, Shanghai, and Jilin, China, between 1972 and 1977, and in 1,974 unexposed workers employed during the same time period. In comparison to general population rates, in the benzidine-exposed group the ratio of observed to expected deaths (SMR) was 17.5 (95% C.I.: 7.5-34.5) and the ratio of observed to expected incident cases (SIR) was 25.0 (95% C.I.: 16.9-35.7). No excess was noted in the unexposed group. The 25-fold increase in bladder cancer incidence in the exposed group was related to level of exposure, with the SIR rising from 4.8 for low exposure to 36.2 for medium exposure, and 158.4 for high exposure. Risks were elevated both for producers of benzidine (SIR = 45.7; 95% C.I.: 20.9-86.8) and for users (SIR = 20.9; 95% C.I.: 12.9-32.0) of benzidine dyes. Benzidine-exposed workers who smoked tobacco had a 31-fold risk (95% C.I.: 20.4-46.4), while non-smoking workers had an 11-fold risk (95% C.I.: 3.6-25.8), suggestive of a multiplicative relationship between these two carcinogens.

Air Pollutants, Occupational↗
PubMed1992

Hypoxia induces synthesis of a novel 22-kDa protein in neonatal rat oligodendrocytes.

Neonatal (3-day-old) rat oligodendrocytes grown in monolayer culture and exposed to increasingly hypoxic culture conditions showed a dramatic reduction in myelin basic protein synthesis but no significant inhibition of Tran35S-label incorporation into oligodendrocyte proteins in general or into structural proteins such as actin. However, there was a dramatic increase in synthesis of a novel 22-kDa protein. Reoxygenation of cultures reversed the synthesis of the 22-kDa protein, and thiol and calpain protease inhibitors (EP-459 and leupeptin) did not prevent synthesis of the protein, suggesting that it did not result from proteolysis. The 22-kDa protein (which we have called hypoxin) was coimmunoprecipitated by a polyclonal antibody to actin but did not react with the anti-actin antibody on western blots. The synthesis of hypoxin accounted for up to 50% of the Tran35S-label incorporated into immunoprecipitated protein, suggesting that it plays a major role in the cell's response to hypoxia. Subcellular fractionation revealed that the 22-kDa protein was largely associated with the cytosolic/cytoskeletal compartment. However, it is unlikely to be one of the cytoskeleton-associated Rho or Rac low-molecular-mass (20-24 kDa) GTP-binding proteins because it did not bind [alpha-32P]GTP on western blots. Oligodendrocytes did not synthesize a 22-kDa protein in response to heat shock but did synthesize the typical 70- and 90-kDa heat-shock proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Analysis of nasal consonants using perceptual linear prediction.

Until recently, speech analysis techniques have been built around the all-pole linear predictive model. This study examines the effectiveness of using the perceptual linear predictive method for analyzing nasal consonants. Six speakers (three men and three women) produced 300 CV syllables with initial nasal consonants /m/ and /n/. A threshold-based boundary detection algorithm was developed to extract nasal segments from the CV contexts. Poles of a fifth-order perceptual linear predictive model were calculated and the frequency of the second pole was used to characterize the place of articulation of nasal consonants. Results indicated that the frequency for the second transformed pole was significantly lower for /m/ than for /n/ and was independent of factors such as a vowel context and gender of the speaker. A nasal identification rate of 86% was obtained based on the frequency of the second pole. The use of the perceptual linear predictive method may thus overcome some difficulties associated with analyzing nasal consonants.

Adult↗
PubMed1992

An adaptive method for tracking voicing irregularities.

A method has been developed for tracking irregularities in the acoustic waveform of a sustained phonation using the adaptive Wiener filter. Irregularities are determined by the technique of correlation cancellation. The algorithm is evaluated using sustained vowels produced by a formant synthesizer and by subjects with and without phonatary disorders. Results indicate that the method is capable of differentiating between normal and abnormal voices. Most significantly, however, it can also track sporadic or nonstationary irregularities in the shape of an individual acoustic wavelet. This method is expected to be a useful tool for the acoustics analysis of voice production.

Adult↗
PubMed1992

Time normalization in voice analysis.

The harmonics-to-noise ratio (HNR) has been widely accepted for quantifying the irregular or noise component of voice. HNR, however, is usually inflated by cycle-to-cycle variations of fundamental frequency period because zero padding is used for time normalization of the wavelet. In this study, a new method was developed for analyzing waveform perturbations of voice. In this method, noise components of voice were calculated from the discrepancies between wavelets after they had been optimally aligned in time. The optimal time normalization of wavelets was accomplished using procedures of dynamic time warping (DTW). This method was evaluated using both synthetic and natural voices, and significant reductions in noise were obtained. The harmonics-to-noise ratio obtained using DTW for time normalization was also shown to be independent of fundamental frequency perturbations.

Acoustics↗
PubMed1992

[Effect of glutamine and glutamine-dipeptide enriched amino acid solution on rat small bowel mucosa regeneration].

To mine the effects of glutamine and it's dipeptide enriched nutrition solution on the gastro-intestinal structure and protein metabolism, 40 male Wistar rats were studied for 8 days. The rats were randomly divided into four groups: sham operation group, standard amino acid solution group, glutamine enriched group and glutamine dipeptide enriched group. Observation parameters were: weight change; serum AA profile analysis; computerized morphometric analysis of mucosa thickness and villus height; total nitrogen balance; and liver, kidney functional results. The data were managed by multiple sample comparison methods (ANOVA of Statview 512 software) on Macintosh PC. Significant level was put on P < 0.05. The results showed that significant differences of body weight, serum glutamine level, nitrogen balance, intestinal mucosa thickness and villus height were found between the control and study groups. No significant difference in liver and kidney function was found. Gln-Ala dipeptide had same effects as free glutamine did.

Amino Acids↗
PubMed1992

[Alteration of calcium uptake and Ca(2+)-ATPase activity of cardiac sarcoplasmic reticulum in rat during ischemia-reperfusion].

Using Langendorff's perfusion model of isolated rat heart, the effect of period of ischemia, ischemia-reperfusion and changes in perfusate pH on the function of calcium uptake of cardiac sarcoplasmic reticulum (SR) was observed. The initial rate and capacity of calcium uptake by SR decreased significantly after 25 min ischemia, and were further worsened when ischemia was prolonged to 40 min. When hearts were subjected to 15 min reperfusion after 25 min ischemia, calcium uptake capacity and initial rate decreased even more in comparison with that of 40 min ischemia. In addition, the calcium dependent ATPase activity of SR was also markedly inhibited. Reperfusion with acid (pH 6.8) or alkaline (pH 8.0) made no significant difference on the aforementioned reperfusion induced changes. The results indicated that myocardial ischemia depressed the calcium transport activity of SR, and this depression was further aggravated with prolonging ischemia. Reperfusion after ischemia exacerbated the ischemic injury. Reperfusion with either acid or alkaline Krebs-Henseleit solution could not improve the calcium uptake function of SR, implying that the pH change does not seem to be an important factor in inducing the SR dysfunction during ischemia-reperfusion.

Animals↗
PubMed1992

Construction and characterization of a high-affinity chimeric anti-colorectal carcinoma antibody ccM4.

We have produced a high-affinity chimeric anti-colorectal carcinoma antibody, ccM4, chimerized in both heavy and light chains by the construction of two expression vectors, the chimeric heavy-chain expression vector mpSV2neo-EP1-Vm4Cr1 and chimeric light-chain vector mpSV2gpt-EP1-VKCK. These vectors contained the neo or gpt gene as a selection marker, the murine immunoglobulin promoter and enhancer (EP1), the genomic DNA fragments of human immunoglobulin constant region (CK and C gamma 1), and murine cDNA fragments of VH and VK region amplified and cloned directly from the B72.3 hybridoma RNA by the polymer chain reaction technique. These two vector DNAs were sequentially transfected into the SP2/0Ag14 cell line. Transfectants were selected in media containing both G418 and mycophenolic acid. The ccM4 antibody was purified from transfectant supernatants with positive binding reactivity for the TAG72 antigen on a protein A column. We demonstrated that ccM4 antibody retained the same high binding reactivity for the TAG72 antigen as its counterpart, the high-affinity chimeric heavy-chain cB72.3m4 antibody. The ccM4 antibody bound specifically to human colon cancer cells, displayed biodistribution patterns similar to cB72.3m4 antibody, and mediated effective antibody-dependent cellular cytotoxicity to human OVCAR3 tumor cells. Therefore, the high-affinity chimeric ccM4 antibody should be useful in cancer immunotherapy.

Animals↗
PubMed1992

[Development of the lens and zonulae in the human embryo].

The embryonic development and ultrastructures of the lens and zonulae in 212 eyes of 131 human embryos were studied by light and electronic microscopy, with the finding that the capsule and zonulae appeared earlier than previously reported. The laminate structure of the capsule was observed in the 7 week embryo, and the early structures of zonulae were discernible in the 10th week on the basement membrane of the non-pigmental epithelium of the ciliary body and on the capsule, indicating that the capsule was specialized basement membrane of the lenticular epithelial cells, and the zonulae originated from the non-pigmental epithelium of the ciliary body and the capsule of lens.

Ciliary Body↗
PubMed1991

Ganglioside levels in hypoxic brains from neonatal and premature infants.

In this study, 13 cases of newborn term-gestational infants and six cases of premature infants who died of hypoxia were selected for the determination of ganglioside levels in several regions of brains obtained at autopsy. Cases were divided into three groups according to the hypoxic interval and gestational age: Group A, six cases of newborn infants. The average time of hypoxia was 6.4 h. Group B, seven cases of newborn infants. The average time of hypoxia was about 71 h. Group C, six cases of premature infants. The average hypoxia time was 34.7 h. Frontal cortex, forebrain, hippocampus, and parahippocampal gyrus and cerebellum of each brain were examined. The method of Ladisch and Gillard (1985) was used to purify and quantify gangliosides. The results showed that total gangliosides decreased significantly in three regions of cerebral hemispheres of group B and in four brain regions of group C, as compared with group A (p less than 0.01). The amount of gangliosides in frontal cortex in group B was lower than in group C (p less than 0.01). The four major gangliosides (GM1, GD1a, GD1b, and GT1b) were all reduced in cerebral hemispheres of group B and C. In hypoxic brains, the percentage of gangliosides also showed some alterations. There was less GD1a in the cerebral hemispheres of group B and the frontal cortex of group C. The amount of GD1b was also less in the frontal cortex and forebrain of group B than in group A or C. The results suggest that severe hypoxia might cause decreases in brain gangliosides that correlate to the severity of brain damage.

Brain Chemistry↗
PubMed1991

Noninvasive estimation of cardiac output.

A noninvasive method of measuring cardiac output is described. The method uses adaptive aorta models in conjunction with femoral and carotid pulse contour waveform measurements to calculate aortic flow. Results are presented from measurements on dogs using internal pressure recordings made with fluid-filled catheters and compared with electromagnetic flow measurements taken in the ascending aorta. Preliminary results using external pulse measurements on patients are also presented and compared with thermal dilution measurements.

Animals↗
PubMed1991

[The embryonic development of iridial muscles].

Development of iridial muscles was observed in 116 fetal eyes (72 human embryos 7 weeks to full gestation). Bundles of microfilaments with local high density spots appeared in the cytoplasm of the anterior pigment epithelium early in 10 week embryos. The high density spots later grew to be the dense-bodies in the myofilaments, the original structure of the pupillary sphincter. In embryos of 4 1/2 months, blood capillaries grew into the sphincter, which was fully developed in the 6th month, and myofilaments of the dilator muscles began to appear in the cytoplasm of peripheral anterior pigment epithelium, with villous protrusions toward the stroma. Many myofilaments with scattered dense-bodies were seen in the protrusions. It was thus confirmed that both the sphincter and dilator muscles originated from the iridial anterior pigment epithelium of neuro-ectoderm; however, the former developed fully to form independent smooth muscle bundles, while the latter was less developed and remained part of the pigment epithelium (myo-epithelium). The appearance of both muscles was earlier than previously reported.

Actin Cytoskeleton↗
PubMed1985

Tumorigenicity testing of primate cell lines in nude mice, muscle organ culture and for colony formation in soft agarose.

Primate neoplastic and finite cell lines were tested in one in vivo and two in vitro test systems: adult nude mice, muscle organ culture (MOC) and soft agarose (SA). Comparison of the sensitivity of the systems indicated that nude mice were inferior to either in vitro system: WI-38 VA13 (an SV40 transformed cell line) did not cause tumours in these animals yet it behaved as if it were neoplastic in MOC and formed colonies in SA. There was complete correlation between results obtained in MOC and SA. All cell lines which produced tumors in vivo were positive in both in vitro test systems. None of the lines which showed normal patterns in MOC and in SA was tumorigenic in nude mice. Since testing in vitro is simpler, faster, and is thought to be reliable, we recommend SA followed by MOC as the initial assays for determining tumorigenicity of cells.

Animals↗