Biomedical subjects
Publications and source records attributed to Y Cheng.
An intrauterine probe electrode was inserted into 100 laboring women and 366 bipolar electrode combinations were tested. A noise-cancelling technique was used with the final 28 subjects to remove competing maternal cardiac signals. Twenty-four (86%) had fetal heart rate tracings with sufficient technical quality to allow determination of the baseline fetal heart rate.
The effect of single and repeated marijuana smoke exposure on fetal EEG was investigated in the chronic fetal lamb model using power spectral analysis. Maternal inhalation of marijuana smoke (n = 9) resulted in a significant reduction in total power and power distribution in the delta (1-4 Hz) band, and an increase in power distribution in the faster frequencies in the first h after smoke inhalation. These EEG changes were not observed following maternal inhalation of placebo smoke (n = 5), nor in animals with 3-5 prior exposures to marijuana smoke (n = 5). These results suggest that the effects of marijuana smoke exposure on fetal EEG is short-lived and tolerance develops rapidly with repeated exposure.
Previous studies of the sources of sex education are reviewed and critically analyzed. Most previous studies have examined the limited issue of which source of sex education is most important, examined the sources of only a few sexual topics, or used inadequate methodology. In the present study, more adequate data regarding the relative contributions of parents, schools, reading, and peers to information about each of 35 different sexual topics were obtained from a sample of 232 male and female, coitally experienced or inexperienced, midwestern college students. Individual reading and peers were the highest rated sources overall and on most of the subcategories of items. Schools were highly rated sources for topics related to the anatomy and physiology of sex and venereal disease. Coitally experienced (CE) individuals reported receiving more information overall than coitally inexperienced (CIE) individuals. However, contrary to previous speculations, CE and CIE individuals did not differ in the amount of information received from parents. Instead, CE individuals received more information through reading and from peers than did CIE individuals. Consistent with previous findings, amount of information received from parents correlated negatively with performance on a sexual knowledge test. Comparison of the present results with previous research suggested a developmental hypothesis, namely, that as individuals develop from early adolescence to young adulthood and become more sexually active, individual reading becomes a more important source of sexual information.
The mechanism of action of low doses of morphine on breathing dynamics in the fetus was studied in 16 fetal lambs with chronically implanted electromyographic electrodes in the diaphragm. Morphine (0.15-2.5 mg/h) caused a significant dose-dependent increase in the number of diaphragmatic bursts per hour, with either an increase or no change in instantaneous breathing rate. There was also a significant dose-related increase in the continuity of the breathing pattern, as indicated by a decrease in the number of apneas per hour, and an increase in epoch duration. Morphine also had a significant effect on the stability of the breathing pattern, with an increase in the percentage of bursts that occurred in stable clusters. All of these effects were completely abolished by concurrent intracerebroventricular administration of either methylnaloxone or methylatropine or by pretreatment with intravenous naloxonazine. These results suggest that stimulation and stabilization of ventilatory activity in the fetal lamb by low doses of morphine are mediated via mu 1-receptors and involve central muscarinic pathways.
The effects of naloxone and naloxonazine (an irreversible mu1 antagonist) administration on fetal breathing movement (FBM) patterns under control, physiologic conditions were studied in 10 fetal lambs with chronically implanted electromyogram electrodes in the diaphragm. Neither naloxone (6 mg/h) nor naloxonazine (34 mg) had any effect on the total number of diaphragmatic electromyogram bursts per hour, mean instantaneous breathing rate, or incidence of breathing. However, naloxonazine caused a more fragmented FBM pattern, as indicated by a significant increase in both the number of apneas and pauses per hour, along with decreased epoch duration. In addition, naloxonazine caused a significant reduction in the stability or regularity of the breathing rate. Naloxone had no effects on the dynamic pattern of the FBM. These results suggest that endogenous opiate peptides play a tonic role at the mu1, receptor to maintain both the continuity and stability of the FBM pattern in late gestation.
One hundred and twelve new cases of Graves' disease were treated by tapazole for 6 months and followed up for another 12 months. The initial dose was 30 mg/d. Clinical and biochemical euthyroidism was achieved within 1 to 3 months, then a maintenance was given until cessation of drugs at 6 months. One hundred and eleven cases completed the study. Remission and relapse were defined at the end of follow-up for 1 year according to the presence or absence of clinical manifestation of hyperthyroidism and the levels of T3 and T4. The results of the 12-month follow-up showed that 46 of 111 cases were in remission, and the remaining 65 cases suffered relapse. A logistic regression model with 4 variables was established, which included thyroid suppression rate and goitre size by palpation at the end of drug treatment, the level of T3 before therapy, and the patients' age. The model had 81.5% sensitivity, 84.8% specificity and 82.9% (92/111) accuracy in predicting the outcome of Graves' disease after withdrawal of drug for 1 year. The results were much better than any other univariate analysis in this study.
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One hundred and fifteen new patients with Graves' hyperthyroidism were received thyroid suppression test after cessation of 6 month course of drug therapy. The results of follow up for another 12 months were that one of them had lost, 48 cases were in remission, and 66 cases had relapsed. The present study shows that thyroid suppression test, including the 4th, 6th and 24th hour suppression rates, is useful in predicting the outcome of drug therapy. The effect of 6th hour suppression rate is better than that of 24th and 4th hours, with 75.8% sensitivity, 75.0% specificity and 75.4% accuracy when 30% of thyroid suppression rate is as out-off point which is decided by ROC curve. It is suggested that 6 hour 30% suppression rate is better than the traditional 24 hour 50% suppression rate in the prediction of outcome of drug therapy.
To understand the situation of snail distribution and to explore the criteria of susceptible zones of schisosomiasis in endemic areas around Poyang Lake, a total of 1,222,910 mu of marshland in lake regions were surveyed for three years from 1982 through 1984 by 400 skillful observers. This article reports the relation between mean density of infected snails and incidence of acute schistosomiasis in marshland. We divided all susceptible marshlands of Poyang Lake area into three types, and found that about one fourth of the area belongs to the first type of susceptible zones, i.e., with high risk to schistosomiasis infection. Longitudinal observation showed that the types of susceptible zones changed very little unless measures of schistosomiasis control were taken. The results of field study suggested that we should put stress of schistosomiasis control on the first type of susceptible marshlands of Poyang Lake in future.
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One hundred and twelve new cases with Graves' disease were treated by tapazole for 6 months and followed-up for another 12 months in a prospective study. One hundred and eleven cases completed the whole course of study, and only one failed to be followed up. The results of the follow-up for 12 mon showed that the remission rate was 41.4% (46/111) and relapse rate was 58.6% (65/111). The present study indicated that the remission or relapse was related with serum levels of T3 before treatment, shrank goiter and disappearance of goiter bruit during the treatment as well as thyroid suppression rate, but not related to sex, age, period of illness before therapy or severity of the disease. It is suggested that a 6-mon antithyroid drug therapy instead of traditional long term therapy may be suitable for those patients who are with a reduced goiter and disappeared goiter bruit during the antithyroid therapy, and suppressible thyroid up-take by T3 and whose serum levels of T3 before treatment are not very high. So the patients may benefit from the short-term therapy. They are not only able to obtain a prolonged remission but also save time and money.
We found incidentally 3 years ago that inosine relieved the symptoms in a patient with Tourette syndrome. Since then, 36 patients suffered from Tourette syndrome were exclusively treated with inosine, 50-90 mg/kg daily in divided doses. The vocal and non-vocal tic attacks were counted either by the observation of an examiner or with a video-tape record. The clinical status was scored as the sum of the number of various tic attacks recorded during a period of 60 minutes (video-tape record) or 20 minutes (direct observation). According to the scores obtained from double blind cross-over trial (11 cases) and open trial (25 cases), the tic attacks were well controlled in 75% of patients treated. A follow-up study by the end of one year medication the efficacy of inosine was still impressive in 50% of patients. Since we have observed that inosine potentiated the release of dopamine from rat striatal synaptosomes, mimicked the action of some dopamine antagonists, it is suggested that inosine might behave as a dopamine antagonist and exerts its effect on Tourette syndrome as haloperidol does.
Random segments of Myxococcus xanthus DNA were cloned in yeast artificial chromosomes (YACs) to construct a physical map of the genome. EcoRI restriction maps of 409 YAC clones with inserts averaging 111 kilobase pairs (kb) were determined. Comparison to the map of a 300-kb region of M. xanthus obtained from clones in Escherichia coli indicates that segments of DNA cloned in YACs are stably maintained in yeast and that their sequences accurately reflect the structure of the Myxococcus genome. The 409 YAC inserts were ordered within 60 map segments (contigs) by aligning their EcoRI restriction maps and by hybridization with 18 gene-specific DNA probes. These 60 map segments may represent the entire Myxococcus genome and could be used to organize its genetic information. This study illustrates the utility of YACs for cloning large segments of DNA and for reliable long-range genomic mapping.
dsg mutants of Myxococcus xanthus are conditionally defective in fruiting body development, including sporulation. Unable to develop on their own, these mutants can assemble fruiting bodies with spores if they are mixed with wild-type cells. To elucidate the developmental defect in dsg mutants by close comparison with wild type, such mutants have been backcrossed by transduction, using a closely linked insertion of transposon Tn5 for selection. Backcrossed dsg mutants form aggregates that are larger, less compact, and less symmetrical than dsg+ fruiting bodies. Also, the starvation-induced sporulation in dsg aggregates is delayed and reduced. However, dsg mutants can be induced by glycerol or dimethyl sulfoxide to sporulate at levels approaching those of wild type. dsg mutants may thus have a primary defect early in development which diminishes their capacity to aggregate and which indirectly decreases the number of fruiting body spores. The linked insertion of Tn5 also facilitated cloning the dsg gene. The cloned dsg+ allele was shown to be dominant to both the dsg-429 and dsg-439 alleles, and both mutant alleles were shown to belong to the same genetic complementation group. Subcloning of restriction fragments, deletions, and insertions of transposon Tn5 agree in locating the dsg gene to an 850-base-pair segment of the cloned region.
Previous work identified the dsg gene as necessary for cell-cell interaction in Myxococcus xanthus. Point mutations of this gene, such as dsg-439, are viable, but insertions of Tn5 within the dsg gene (dsg::Tn5) are lethal. Partial diploids, dsg::Tn5/dsg+ or dsg::Tn5/dsg-429 or dsg::Tn5/dsg-439, are also viable, showing that the lethal effect of the haploid insertions is due to loss of function. Thus the evidence implies that the dsg gene is essential for viability as well as development, but its essential quality differs between growth and development because dsg-429 and dsg-439 mutants grow normally, but are unable to develop.
The effect of neurotensin (NT) on the release of endogenous dopamine (DA) of rat striatal synaptosomes was studied. In the basic medium with Ca++ (5mM K+ and 1.2 mM Ca++), spontaneous release of DA was determined to be 12.03 +/- 1.12 pmol/mg protein, while in the Ca++-free basic medium containing EGTA (2.0 mM), the amount of DA released was still up to 11.2 +/- 1.06 pmol/mg protein. NT in 10(-4)-10(-6) M range tested potentiated both the spontaneous and K+-induced release of DA in Ca++-free medium. In addition, NT in 10(-4) M, but not in lower concentrations tested, potentiated the spontaneous, Ca++-dependent release of DA. It is suggested that the effect of NT on DA release is mediated by the specific NT receptors at the DA axonal terminals. The possibility, however, that NT has some influence on the carrier-mediated process of the membrane might not be ruled out.
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