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Biomedical subjects

H Yin

Publications and source records attributed to H Yin.

At least 145 records · Page 8Linked to original sources
PubMed1996

[Epidemiological survey of Graves' disease on a hundred thousand people in Daging area].

OBJECTIVE: To study the incidence of Graves' disease and associated factors. METHODS: A total of 100123 people aged 15-79 in Daqing region were surveyed epidemiologically. The investigations were conducted for an average two years. RESULTS: 301 patients with Graves' disease were newly diagnosed, 74 of them (1.6/1000) were males and 227 (4.1/1000) females. The total incidence was 3.0/1000. The incidence had significant differences between ages and occupations. Investigations of 18 associated factors for Graves' disease by using the Logistic multivariate regression analysis showed the following pathological factors, virus history, psychological stimulation, food, drugs, family history, education, distributions, etc. CONCLUSION: This study may provide the theoretical evidence for prevention and treatment of Grave's disease.

Adolescent↗
PubMed1996

[Effect of dietary selenium and germanium on the precancerous lesion in rat glandular stomach induced by N-methyl-N'-nitro-N-nitrosoguanidine].

N-Methyl-N'-nitrosoguanidine (MNNG) was administered (100 mg/L) in drinking water in 100 Wistar rats for 24 weeks to induce the precancerous lesion in glandular stomach. 77 rats with the precancerous lesion in glandular stomach were divided into 3 groups randomly at the 25 thweek. Yeast selenium (Yse, 4 mg/L) and carboxyethyl germanium sesquioxide (Ge-132, 600 mg/L) in drinking water were administered respectively in the corresponding treatment groups: 100 ml/MNNG in drinking water was administered in the treatment group, and 100 ml/MNN in drinking water was administered in the treatment group and control group for another 5 weeks. The experiment ended at the end of the 37th week. The results showed that the incidence of glandular stomach cancer in the Yse group was significantly lower than that in the control group; the infiltrating depth of glandular stomach cancer in the Yse group and the Ge-132 group was remarkably shallower than that in the control group. These findings suggest that Yse and Ge-132 have some preventive effect on the precancerous lesion in rat glandular stomach induced by MNNG.

Animals↗
PubMed1996

[Clinical application of soft-tissue flap with an intercostal vascular pedicle from the chest wall in the trachea surgery].

Between 1976 and 1995, 11 cases of side-wall defect repairment or circumferential reconstruction of trachea were performed using chest-wall tissue flap with an intercostal vascular pedicle. The indications were benign or malignant tumors of the tracheal side wall, lung cancers of the right upper lobe involving the side wall of the trachea and/or carina. The transverse diameter of the tracheal defect after removing the tumor was less than half of the tracheal circumference. Furthermore, we foun it feasible to reconstruct the trachea by using a tissue tube created by wrapping a chest-wall tissue flap over a temporary stent in case of long-segment tracheal resection of tracheal tumor or benign stenosis where. The defect was too long to be repaired by end-to-end anastomosis. The surgical technique & instructions were described.

Carcinoma, Adenoid Cystic↗
PubMed1995

Transcription against an applied force.

The force produced by a single molecule of Escherichia coli RNA polymerase during transcription was measured optically. Polymerase immobilized on a surface was used to transcribe a DNA template attached to a polystyrene bead 0.5 micrometer in diameter. The bead position was measured by interferometry while a force opposing translocation of the polymerase along the DNA was applied with an optical trap. At saturating nucleoside triphosphate concentrations, polymerase molecules stalled reversibly at a mean applied force estimated to be 14 piconewtons. This force is substantially larger than those measured for the cytoskeletal motors kinesin and myosin and exceeds mechanical loads that are estimated to oppose transcriptional elongation in vivo. The data are consistent with efficient conversion of the free energy liberated by RNA synthesis into mechanical work.

Biophysical Phenomena↗
PubMed1995

Designing safer chemicals: predicting the rates of metabolism of halogenated alkanes.

A computational model is presented that can be used as a tool in the design of safer chemicals. This model predicts the rate of hydrogen-atom abstraction by cytochrome P450 enzymes. Excellent correlations between biotransformation rates and the calculated activation energies (delta Hact) of the cytochrome P450-mediated hydrogen-atom abstractions were obtained for the in vitro biotransformation of six halogenated alkanes (1-fluoro-1,1,2,2-tetrachloroethane, 1,1-difluoro-1,2,2-trichloroethane, 1,1,1-trifluro-2,2-dichloroethane, 1,1,1,2-tetrafluoro-2-chloroethane, 1,1,1,2,2,-pentafluoroethane, and 2-bromo-2-chloro-1,1,1-trifluoroethane) with both rat and human enzyme preparations: In(rate, rat liver microsomes) = 44.99 - 1.79(delta Hact), r2 = 0.86; In(rate, human CYP2E1) = 46.99 - 1.77(delta Hact), r2 = 0.97 (rates are in nmol of product per min per nmol of cytochrome P450 and energies are in kcal/mol). Correlations were also obtained for five inhalation anesthetics (enflurane, sevoflurane, desflurane, methoxyflurane, and isoflurane) for both in vivo and in vitro metabolism by humans: In[F(-)]peak plasma = 42.87 - 1.57(delta Hact), r2 = 0.86. To our knowledge, these are the first in vivo human metabolic rates to be quantitatively predicted. Furthermore, this is one of the first examples where computational predictions and in vivo and in vitro data have been shown to agree in any species. The model presented herein provides an archetype for the methodology that may be used in the future design of safer chemicals, particularly hydrochlorofluorocarbons and inhalation anesthetics.

Animals↗
PubMed1995

Reentrant arrhythmias in the subacute infarction period. The proarrhythmic effect of flecainide acetate on functional reentrant circuits.

BACKGROUND: The Cardiac Arrhythmia Suppression Trial has shown that flecainide was associated with an increased incidence of sudden cardiac death in postinfarction patients. The exact mechanism(s) of the proarrhythmic effects of flecainide remain unclear. We performed a detailed analysis of the electrophysiological and proarrhythmic effects of flecainide in a well-characterized model of reentrant arrhythmias in the subacute phase of myocardial infarction. METHODS AND RESULTS: Sixteen dogs were studied 4 days after ligation of the left anterior descending coronary artery. Isochronal mapping of ventricular activation showed that flecainide facilitated both the induction and sustenance of ventricular tachycardia, especially at shorter basic cycle lengths. Flecainide had negligible effect on the length of the arc of functional conduction block but markedly depressed conduction of the common reentrant wave front that was usually oriented parallel to fiber axis. Whole heart mapping was analyzed in combination with basic measurements of the effects of flecainide on conduction and refractory properties of both normal and ischemic myocardia using a high-resolution cross electrode consisting of four orthogonal arms, each comprised of 16 poles with an interelectrode spacing of 500 microns. The electrode was especially designed to study the effects of the drug on anisotropic conduction as determined by a linear regression of activation time and distance in each direction. Flecainide resulted preferentially in more marked rate-dependent depression of conduction in ischemic compared with normal myocardium. On the other hand, the effect of flecainide on refractoriness in both normal and ischemic myocardia was negligible. CONCLUSIONS: Because flecainide caused no significant change in refractoriness in both normal and ischemic myocardia, there was no difference in the dimension of the potential reentrant pathway, that is, the continuous line of functional conduction block, around which the reentrant wave fronts circulate. Yet, flecainide resulted in significant rate-dependent slowing of conduction preferentially in ischemic myocardium. The additional slowing of conduction of the common reentrant wave front coupled with minimal changes in the length of the reentrant pathway allowed additional time for the wave front to reexcite normal myocardium on the proximal side of the arc of block. After flecainide, reentry could be induced in hearts in which reentry could not be induced during control. The same proarrhythmic mechanism explains the propensity of nonsustained figure-8 reentrant tachycardias to become sustained after flecainide.

Animals↗
PubMed1995

Metabolism of 1-fluoro-1,1,2-trichloroethane, 1,2-dichloro-1,1-difluoroethane, and 1,1,1-trifluoro-2-chloroethane.

1-Fluoro-1,1,2-trichloroethane (HCFC-131a), 1,2-dichloro-1,1-difluoroethane (HCFC-132b), and 1,1,1-trifluoro-2-chloroethane (HCFC-133a) were chosen as models for comparative metabolism studies on 1,1,1,2-tetrahaloethanes, which are under consideration as replacements for ozone-depleting chlorofluorocarbons (CFCs). Male Fischer 344 rats were given 10 mmol/kg ip HCFC-131a or HCFC-132b or exposed by inhalation to 1% HCFC-133a for 2 h. Urine collected in the first 24 h after exposure was analyzed by 19F NMR and GC/MS and with a fluoride-selective ion electrode for the formation of fluorine-containing metabolites. Metabolites of HCFC-131a included 2,2-dichloro-2-fluoroethyl glucuronide, 2,2-dichloro-2-fluoroethyl sulfate, dichlorofluoroacetic acid, and inorganic fluoride. Metabolites of HCFC-132b were characterized as 2-chloro-2,2-difluoroethyl glucuronide, 2-chloro-2,2-difluoroethyl sulfate, chlorodifluoroacetic acid, chlorodifluoroacetaldehyde hydrate, chlorodifluoroacetaldehyde-urea adduct, and inorganic fluoride. HCFC-133a was metabolized to 2,2,2-trifluoroethyl glucuronide, trifluoroacetic acid, trifluoroacetaldehyde hydrate, trifluoroacetaldehyde-urea adduct, inorganic fluoride, and a minor, unidentified metabolite. With HCFC-131a and HCFC-132b, glucuronide conjugates of 2,2,2-trihaloethanols were the major urinary metabolites, whereas with HCFC-133a, a trifluoroacetaldehyde-urea adduct was the major urinary metabolite. Analysis of metabolite distribution in vivo indicated that aldehydic metabolites increased as fluorine substitution increased in the order HCFC-131a < HCFC-132b < HCFC-133a. With NADPH-fortified rat liver microsomes, HCFC-133a and HCFC-132b were biotransformed to trifluoroacetaldehyde and chlorodifluoroacetaldehyde, respectively, whereas HCFC-131a was converted to dichlorofluoroacetic acid. No covalently bound metabolites were detected by 19F NMR spectroscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Activation time determination by high-resolution unipolar and bipolar extracellular electrograms in the canine heart.

INTRODUCTION: To identify the optimal criteria for activation time (AT) determination of bipolar electrograms from normal hearts, a high-resolution cross electrode array comprising 128 unipolar electrodes of 500-microns spacing was used to record extracellular potentials from the left ventricular epicardium of 12 dog hearts. METHODS AND RESULTS: Recordings were made during broad wavefront propagation (B wave) and local elliptical wavefront propagation (E wave). Characteristics of 863 bipolar electrograms (1-mm spacing) were constructed from unipolar data standardized for differences in polarity, then classified morphologically. Features for bipolar AT determination were compared to the time of the negative peak of the first temporal derivative of a unipolar electrogram situated mid-way between the bipoles. During B wave, three distinct morphologies were observed: uniphasic (61%), biphasic (23%), and triphasic (16%). Peak voltage of uniphasic and triphasic signals was the best predictor of AT (error: 0.6 +/- 0.6 msec and 0.6 +/- 0.8 msec, respectively). During E wave, parallel orientation of the bipoles with respect to the direction of impulse propagation wavefront resulted in uniphasic signals (> 99%), while for perpendicular orientation of the bipoles, electrogram morphology was variable. For parallel orientation of the bipoles, peak negative voltage was the best predictor of AT for both longitudinal and transverse propagation, while for perpendicular bipole orientation, peak negative voltage was a less reliable predictor for propagation along both fiber axes. Increasing interpolar distance resulted in a degradation in AT accuracy for B wave (from 0.6 +/- 0.6 msec at 1 mm to 1.1 +/- 1.2 msec at 7 mm) and for E wave (from 0.4 +/- 0.3 msec at 1 mm to 3.1 +/- 2.9 msec at 7 mm). CONCLUSIONS: (1) The accuracy of bipolar electrograms is sensitive to wavefront direction, bipole orientation, and interpolar distance; (2) peak negative voltage of uniphasic and triphasic signals is a reliable predictor of AT, but only for B wave; (3) a maximum interpolar distance of 2 mm and bipole orientation parallel to the direction of the impulse wavefront are minimally required for accurate determination of AT during impulse propagation initiated near the recording electrodes; and (4) for impulses initiated near the recording site in normal tissue, a biphasic or triphasic morphology almost certainly indicates that the bipolar electrode is oriented perpendicular to the wavefront direction, irrespective of fiber orientation.

Action Potentials↗
PubMed1995

On the distribution and convergence of feature space in self-organizing maps.

In this paper an analysis of the statistical and the convergence properties of Kohonen's self-organizing map of any dimension is presented. Every feature in the map is considered as a sum of a number of random variables. We extend the Central Limit Theorem to a particular case, which is then applied to prove that the feature space during learning tends to multiple gaussian distributed stochastic processes, which will eventually converge in the mean-square sense to the probabilistic centers of input subsets to form a quantization mapping with a minimum mean squared distortion either globally or locally. The diminishing effect, as training progresses, of the initial states on the value of the feature map is also shown.

Algorithms↗
PubMed1995

[Physicochemical characteristics of gentamicin polybutylcyanoacrylate nanoparticles].

Several formulations of gentamicin nanoparticle (GM-NP) colloids were prepared by the emulsion polymerization technique using the polybutylcyanoacrylate as the carrier. Various kinds of physicochemical characteristics, such as particle size and size distribution, drug loading and associating ratio, surface zeta potential, surface tension, turbidity, relative density, viscosity, refractive index and acidity were observed, determinated and compared. The results of the experiments have contributed to a full understanding of the physicochemical characteristics of gentamicin nanoparticles and also provided a basis for the establishment of the quality evaluation methods.

Drug Carriers↗
PubMed1995

[Comparison of toxic effects of brucite and aluminium-treated chrysotile on macrophage].

Toxicity of brucite and two kinds of chrysotile (Xinkang and Sichuan chrysotile) treated with aluminium chloride to alveolar macrophage from guinea pigs was compared in vitro. Results showed changes of toxicity, indicated as generation of O2-., increase in membrane lipid fluidity and leakage of intracellular potassium, etc., caused by aluminium-treated chrysotile, were significantly lower than those by bructite of same dose (P < 0.05 and P < 0.01, respectively), and changes of other toxic indicators, such as release of lactic dehydrogenase (LDH) and acid phosphatase (ACP) from macrophage and its mortality, were similar to those by brucite. It suggests aluminium chloride can be used to antagonize pathogenic bioactivity of chrysotile in practice.

Aluminum Chloride↗
PubMed1995

[Use of parenteral nutritional support in patients with gastric cancer: the relationship of protein turn over, immunocompetence and tumor cell kinetics].

In order to elucidate the effect of preoperative parenteral nutritional support (PNS) on protein metabolism, host immunocompetence and tumor cell kinetics, two prospective trials were made in patients with gastric cancer. All the patients were given PNS for 7 days in addition to oral intake. The positive nitrogen balance and increase of protein anabolic rate was greater in PNS groups than in control group. There was a moderate increase in NKC after PNS. The rise in CD4+ was significant (P < 0.05). The percentage of G0/G1 cells fell after PNS (P < 0.01), while that of the whole proliferative phase (S + G2 + M) rose (P < 0.05). These changes were not noted in normal gastric mucosa. In conclusion, despite of stimulating tumor cell proliferation, PNS helps to promote whole body protein synthesis and to amelio-rate the immunocompetence of advanced gastric cancer patients before operation.

Adult↗
PubMed1995

[Determination of ursodeoxycholic acid and chenodeoxycholic acid in Chinese medicinal compound preparations by TLC-densitometry].

The contents of ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) in Chinese medicinal compound preparations have been determined by TLC-densitometry. The determination wavelength was 375nm and reference wavelength was 700nm. For UDCA the linear range was 3.0-15.0 micrograms and recovery was 97.2% (RSD = 1.2%), and for CDCA the linear range was 4.0-20.0 micrograms and recovery was 99.3% (RSD = 2.1%).

Animals↗
PubMed1995

[Clinicopathological features and surgical treatment of early gastric cancer].

We analyzed retrospectively the clinicopathological data obtained from 126 patients with early gastric cancer (EGC) to elucidate the relationship between pathological patterns and lymphatic metastasis and the criteria of selecting appropriate surgery. Lymph node metastasis was 3.1% (2/65) in mucosal and 16.4% (10/61) in submucosal tumors respectively (P < 0.05). 26 patients with tumors smaller than 10 mm had no lymphatic metastasis, and 100 patients with tumors larger than 10mm in size had 8% (8/100) n1 positive, 4% (4/100) n2 positive and 7% (7/100) lymphatic duct invasion (P < 0.05). The 5-year survival rate in patients with lymphatic metastasis (79%, 15/19) was significantly lower than that in patients without lymphatic metastasis (97.2%, 104/107) (P < 0.01). It seemed that the most important prognostic factor is whether the presence of lymphatic metastasis or not. Lymphadenectomy is expected to improve the survival rate in EGC. D2 procedure is generally recommended as a standard operation for EGC, especially for the submucosal or larger lesion. Anyhow, D1 operation is sufficient for mucosal or smaller cancer, and D3 is suitable only for EGC patients with multifoci, superficially spreading type and group 3 lymph node metastasis.

Adenocarcinoma↗
PubMed1995

[Experimental study of trachea reconstruction using autogenous soft tissue of chest wall with the stent].

The dog trachea were reconstructed after the trachea resection using the tubule made by autogenous intercostal compound soft tissue, including intercostal muscle, costal periosteum, and pleura, with pedicle of the intercostal vessels. A stent of fine wire was implanted inside of the reconstructed trachea as supporting. The postoperative result in the short period was satisfied, the operative complications, such as anastomotic leakage, granulation, anastomotic stenosis, and stent moving were not common. The tubule design, operative procedure, the postoperative local X-ray and the fiberscopic findings in the dogs were introduced. The study provides experimental evidences for clinical trachea reconstruction.

Animals↗
PubMed1994

Complete cDNA sequence of a human dioxin-inducible mRNA identifies a new gene subfamily of cytochrome P450 that maps to chromosome 2.

Previously, levels of a novel human mRNA, detected by a recombinant cDNA designated clone 1, were shown to be increased 50-fold in response to treatment of a keratinocyte cell line with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), in part as a function of increased rates of gene transcription (Sutter, T.R., Guzman, K., Dold, K.M., and Greenlee, W.F. (1991) Science 254, 415-418). Here we report the complete corresponding 5.1-kilobase cDNA sequence. A single open reading frame that predicts a protein of 543 amino acid residues was determined by computer-assisted analysis of the cDNA sequence. This predicted protein identifies a new gene subfamily of cytochrome P450, cytochrome P4501B1 (CYP1B1), that maps to human chromosome 2. Southern blot analysis of genomic DNA indicates that the human CYP1B subfamily is likely to contain only this single gene. Northern blot analysis of RNA isolated from primary cultures of normal human epidermal keratinocytes showed approximately 100-fold increased levels of the CYP1B1 mRNA after treatment with 10 nM TCDD for 24 h. Low levels of constitutive CYP1B1 mRNA were detected in 15 different human tissue samples. These results indicate that CYP1B1 is expressed in many normal human tissues and advance our understanding of the complexity of a gene family of cytochromes P450 whose expression is altered by TCDD.

Amino Acid Sequence↗