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Biomedical subjects

X Huang

Publications and source records attributed to X Huang.

At least 649 records · Page 36Linked to original sources
PubMed1993

[Observation on the distribution of LSIPs along three yang meridians as well as ren and du meridians].

The results of our previous works demonstrated that the low skin impedance points (LSIPs) basically distributed along the meridian courses. In order to further clarify what extent LSIPs distributed along the meridians and the feature of distribution of LSIPs in different part of the body, the Three Yang Meridians of Foot as well as Ren and Du Meridians were studied in this work once again. Twenty five volunteers were under observation. As known to all, the Three Yang Meridians of Foot, which travel over several body regions, are the longest three with most complicated courses, among the Twelve Normal Meridians. Ren and Du meridians, which travel along the anterior and posterior median line of the trunk respectively, are the representative of the Eight Extra Meridians. Regardless of their particular travelling courses, the overwhelming majority of LSIPs located right on or within 5 mm bilaterally to their courses. It could be found in non-meridian area only in a few cases. The results of observation on the back is especially to be noticed. Evidently, LSIPs appeared randomly when the exploring electrode moved forward from one side of the back, crossed 5 meridians in succession, to another side. Even so, viewing the situation as a whole, LSIPs still concentrated along 5 bands, basically coincided with the course of Du Meridian and Three Yang Meridians of Foot. The results further confirmed that LSIPs really distributed along the meridian courses in the main.

Adult↗
PubMed1993

Vasoactive intestinal peptide stimulates the growth of rat hepatoma cells in vitro.

Using tetrazolium colorimetric assay (MTT assay) and cell counting methods, the effect of vasoactive intestinal peptide (VIP) on the growth of cultured rat hepatoma FSK-7902 cells was investigated. The results showed that VIP obviously stimulated the proliferation of the rat hepatoma cells. The growth promoting effect increased with VIP concentration. Exposure to VIP for 12 h followed by removal of the peptide resulted in sustained growth promotion for several days.

Animals↗
PubMed1993

[Effect of superoxide dismutase on experimental allergic uveitis].

In this study, experimental allergic uveitis (EAU) in guinea pigs was induced by an injection of bovine serum albumin (BSA) into the vitreous after having pre-immunized them intradermally with BSA plus incomplete Freund adjuvant, and the effect of superoxide dismutase (SOD) on EAU was observed. The result showed that, histopathologically, the phlogistic cell infiltration and exudation within the anterior ocular part of the SOD- treated animals reduced notably. It is suggested that SOD which can scavenge the free radical superoxide anion may alleviate the cellular reaction in the pathological process of uveitis.

Animals↗
PubMed1993

[Clinical observation of the effect of pretreatment with nifedipine in preventing oxygen free radicals in the cardiopulmonary release bypass operation].

The effect of pretreatment with nifedipine in preventing oxygen free radicals release was observed in the cardiopulmonary bypass (CPB) operation. Twenty cases were divided into two groups for comparison. Nifedipine (0.6 mg/kg) was given to the test group. MDA, XO, UA and SOD were measured. These examinations were taken at pre-aortic clamping, 15 min after aortic clamping, and 30, 60, 120, 180 min after reperfusion. The results indicated that pretreatment with nifedipine reduced oxygen free radicals release in the CPB operation.

Adolescent↗
PubMed1993

Novel serotonergic agents.

The preliminary structure-activity relationships are described for a series of substituted phenethylamines that induce the release of neuronal serotonin. Structures that also have the ability to release neuronal catecholamines are toxic to serotonin neurons, leading to long-term reductions in serotonin markers in rat brain. Conversely, compounds that are selective for the serotonin uptake carrier, and do not affect catecholamines, are not neurotoxic. It is suggested that these novel, selective serotonin releasing agents may find therapeutic utility in disorders where serotonin uptake inhibitors are currently employed.

Neurons↗
PubMed1993

Mathematic proof of Schachar's hypothesis of accommodation.

To evaluate whether there is increased or decreased zonular tension during accommodation, we developed a qualitative small displacement model using Rayleigh's method to determine the characteristics of the human lens changes that occur during accommodation. We found that the optical power of the human lens increased linearly with zonular tension. Our results definitely prove Schachar's hypothesis of accommodation.

Accommodation, Ocular↗
PubMed1992

p-methylthioamphetamine is a potent new non-neurotoxic serotonin-releasing agent.

p-Methylthioamphetamine (MTA), was compared to p-chloroamphetamine (PCA) in a number of pharmacological assays. MTA was about 2-fold more potent than PCA at inhibiting synaptosomal uptake of [3H]5-hydroxytryptamine ([3H]5-HT), and about 7-fold and 10-fold less potent than PCA at inhibiting synaptosomal uptake of [3H]dopamine and [3H]norepinephrine, respectively. In drug discrimination assays, MTA was nearly equipotent to PCA in animals trained to discriminate saline from 3,4-methylenedioxymethamphetamine (MDMA), or two related analogues S-(+)-N-methyl-1-(1,3-benzodioxol-5-yl)-2-butanamine (S-MBDB) or 5-methoxy-6-methyl-2-aminoindan (MMAI). MTA caused dose-dependent increases of tritium efflux from superfused rat frontal cortex slices preloaded with [3H]5-HT, comparable to that induced by an equal molar concentration of PCA. The potential neurotoxicity of MTA was examined by measuring monoamine and metabolite levels at one week following an acute dose. A 10 mg/kg dose of PCA caused a 70-90% decrease of cortical, hippocampal and striatal 5-HT and 5-hydoxyindoleacetic acid (5-HIAA) levels, while twice the molar dose of MTA (21.3 mg/kg) had no effect. Thus, MTA is a potent, selective, serotonin releaser, apparently devoid of serotonin neurotoxic effects. This work also supports the idea that catecholamine systems may play a critical role in the neurotoxicity of PCA-like compounds.

Amphetamines↗
PubMed1992

Benzofuran bioisosteres of hallucinogenic tryptamines.

The benzofuran analogues of the hallucinogens 5-methoxy-N,N-dimethyltryptamine and 5-methoxy-alpha-methyltryptamine were synthesized and evaluated for affinity at the serotonin 5-HT2 and 5-HT1A receptors in rat brain homogenate, labeled with [125I]-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane ([125I]DOI) and [3H]-8-hydroxy-2-(N,N-di-n-propylamino)tetralin ([3H]-8-OH-DPAT), respectively. At the 5-HT2 receptor, the benzofurans had slightly decreased affinities, approximately one-third and one-sixth those of the indoles, for the primary amines and the tertiary amines, respectively. The benzofurans also had lower affinity at the 5-HT1A receptor, but decreased only about 20-30% from that of the indole isosteres. Thus, the 5-HT1A receptor is less discriminating with respect to preference for an indole versus a benzofuran, although all of the compounds did have higher affinities for the 5-HT2 receptor than for the 5-HT1A receptor. It is suggested that benzofurans may be useful in the design of serotonin receptor ligands.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1992

Molecular cloning and expression of Bacillus subtilis bglS gene in Saccharomyces cerevisiae.

A 2.7-kb EcoRI DNA fragment carrying a Bacillus subtilis endo-beta-1,3-1, 4-glucanase gene (bglS) from the E. coli plasmid pFG1 was cloned into an Escherichia coli/yeast shuttle vector to construct a hybrid plasmid YCSH. The hybrid plasmid was used to transform Saccharomyces cerevisiae, and the bglS gene was expressed. Variation between levels of bglS gene expression in S. cerevisiae was about 2.3-fold, depending on the orientation of the 2.7-kb DNA fragment. Assay of substrate specificity and optimal pH of the enzyme demonstrated that the enzyme encoded by YCSH (bglS) was identical with that found in B. subtilis, but the expression level of bglS gene in S. cerevisiae (YCSH) was much lower than that in E. coli (YCSH).

Bacillus subtilis↗
PubMed1992

An O (N2 log N) restriction map comparison and search algorithm.

We present an O (R log P) time, O (M+P2) space algorithm for searching a restriction map with M sites for the best matches to a shorter map with P sites, where R, the number of matching site pairs, is bounded by MP. As first proposed by Waterman et al. (1984, Nucl. Acids Res. 12, 237-242) the objective function used to score matches is additive in the number of unaligned sites and the discrepancies in the distances between adjacent aligned sites. Our algorithm is basically a sparse dynamic programming computation in which "candidate lists" are used to model the future contribution of all previously computed entries to those yet to be computed. A simple modification to the algorithm computes the distance between two restriction maps with M and N sites, respectively, in O (MN (log M+log N)) time.

Algorithms↗
PubMed1992

A contig assembly program based on sensitive detection of fragment overlaps.

An effective computer program for assembling DNA fragments, the contig assembly program (CAP), has been developed. In the CAP program, a filter is used to eliminate quickly fragment pairs that could not possibly overlap, a dynamic programming algorithm is applied to compute the maximal-scoring overlapping alignment between each remaining pair of fragments, and a simple greedy approach is employed to assemble fragments in order of alignment scores. To identify the true fragment overlaps, the dynamic programming algorithm uses specially chosen sets of alignment parameters to tolerate sequencing errors and to penalize "mutational" changes between different copies of a repetitive sequence. The performance tests of the program on fragment data from genomic sequencing projects produced satisfactory results. The CAP program is efficient in computer time and memory; it took about 4 h to assemble a set of 1015 fragments into long contigs on a Sun workstation.

Algorithms↗
PubMed1992

Parallelization of a local similarity algorithm.

The local similarity problem is to determine the similar regions within two given sequences. We recently developed a dynamic programming algorithm for the local similarity problem that requires only space proportional to the sum of the two sequence lengths, whereas earlier methods use space proportional to the product of the lengths. In this paper, we describe how to parallelize the new algorithm and present results of experimental studies on an Intel hypercube. The parallel method provides rapid, high-resolution alignments for users of our software toolkit for pairwise sequence comparison, as illustrated here by a comparison of the chloroplast genomes of tobacco and liverwort.

Algorithms↗
PubMed1992

Dynamic programming algorithms for restriction map comparison.

For most sequence comparison problems there is a corresponding map comparison algorithm. While map data may appear to be incompatible with dynamic programming, we show in this paper that the rigor and efficiency of dynamic programming algorithms carry over to the map comparison algorithms. We present algorithms for restriction map comparison that deal with two types of map errors: (i) closely spaced sites for different enzymes can be ordered incorrectly, and (ii) closely spaced sites for the same enzyme can be mapped as a single site. The new algorithms are a natural extension of a previous map comparison model. Dynamic programming algorithms for computing optimal global and local alignments under the new model are described. The new algorithms take about the same order of time as previous map comparison algorithms. Programs implementing some of the new algorithms are used to find similar regions within the Escherichia coli restriction map of Kohara et al.

Algorithms↗
PubMed1992

A comparison of intracellular changes in porcine eggs after fertilization and electroactivation.

The experiments compare intracellular changes in porcine eggs induced by electrical activation with those induced by sperm penetration. Adequate electrostimulation induces changes in both cortical granule exocytosis and protein synthesis similar to those induced by sperm during fertilization. However, ionic changes induced by electrostimulation differ markedly from those initiated at fertilization. Thus, dynamic video imaging using Fura-2 as a Ca2+ probe provides evidence that parthenogenetic activation induced by electrostimulation is initiated by a single sharp rise in the concentration of intracellular free calcium ([Ca2+]i) in the egg. The intracellular Ca2+ transient increase is triggered by an influx of extracellular Ca2+ immediately after electrostimulation. The amplitude of the intracellular Ca2+ transient increase is a function both of the extracellular Ca2+ concentration and of electric field parameters (field strength and pulse duration). Imaging demonstrates further that a single electrical pulse can only induce a single Ca2+ transient which usually lasts three to five minutes; no further Ca2+ transients are observed unless additional electrical stimuli are applied. By contrast, sperm-induced activation is characterised by a series of Ca2+ spikes which continue for at least 3 hours after sperm-egg fusion. The pattern of Ca2+ spiking after fertilization is not consistent during this period but changes both in frequency and amplitude. Overall, the results demonstrate that, although electrostimulation induces both cortical granule exocytosis and protein reprogramming in porcine eggs, it does not reproduce the pattern of [Ca2+]i changes induced by sperm entry at fertilization.

Animals↗
PubMed1992

Computerized plotting of low skin impedance points.

The distribution of low skin impedance points (LSIP) was studied on 68 subjects with a computer system designed for the measurement of skin impedance. The results demonstrated that LSIPs were basically distributed along the 14 channels, the overwhelming majority located right on or within 5 mm bilaterally to their courses. LSIPs were found in the area between every two channels only in a few cases. Moreover, there was no marked natural fluctuation of skin impedance in the human body and the distribution of LSIPs was considerably stable, which could be plotted on any day in the experiment. It is clear that such particular distribution of LSIPs along channels was really a biological phenomenon, not an experimental error. However, the distribution of low skin impedance was not an uninterrupted solid line but a series of LSIPs basically along the channel course. The method used in this work was accurate, reliable and repeatable which has upgraded the measurement of LSIPs to a new level. Under certain conditions, skin impedance can be used as an objective index in channel research.

Adult↗