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Biomedical subjects

Y Peng

Publications and source records attributed to Y Peng.

At least 199 records · Page 11Linked to original sources
PubMed1991

Replacement of cholesterol gallstones by murideoxycholyl taurine gallstones in prairie dogs fed murideoxycholic acid.

The effect of two hydrophilic bile acids, murideoxycholic acid (3 alpha,6 beta-dihydroxy-5 beta-cholanoic acid) and ursodeoxycholic acid, on cholesterol and bile acid metabolism and hepatic pathology and gallstone composition was studied in the prairie dog. Cholesterol gallstones were induced by feeding a diet containing 1.2% cholesterol for 75 days. The animals were divided into six groups, and gallstone regression was studied as follows: groups 2 and 5, chow plus 0.2% cholesterol; groups 3 and 6, chow plus 0.2% cholesterol plus 0.15% ursodeoxycholic acid; groups 4 and 7, chow plus 0.2% cholesterol plus 0.15% murideoxycholic acid. Animals in groups 2 to 4 were killed after an additional 6 wk; animals in groups 5 to 7 were killed after an additional 12 wk. Gallstone dissolution did not occur in any group. The gallstones in groups 2, 3, 5 and 6 were typical cholesterol aggregates, as determined by polarized light microscopy and Fourier transform infrared spectrometry. The gallstones of the murideoxycholic acid group were large, solitary, dark stones that appeared radiopaque under 22 kVp x-ray examination. Scanning electron microscopy showed that in these stones the cholesterol crystals had been replaced by an amorphous material, both within the stone and on the stone surface. Chemical analysis indicated that at the end of 12 wk the calcium/sodium salt of the taurine conjugate of murideoxycholic acid (murideoxycholyl taurine) comprised 70% of the stones; protein, cholesterol and small amounts of other bile salts were also present. In vitro studies confirmed the insolubility of the sodium and calcium salts of murideoxycholyl taurine. These studies indicate that the hydrophilic bile acids, murideoxycholic acid and ursodeoxycholic acid, did not achieve gallstone dissolution under the conditions used. In the animals fed murideoxycholic acid, an insoluble calcium salt of murideoxycholyl taurine replaced cholesterol as the major constituent of gallbladder stones. This is the first example of an insoluble dihydroxy taurine-conjugated bile acid; administration of the unconjugated bile acid induced precipitation of a kind of gallstone not previously reported. The final result was transformation of cholesterol stones to bile salt stones.

Animals↗
PubMed1991

Dialyzability and binding of digoxin-like immunoreactive factors (DLIF) with serum macromolecules in uremic patients on hemodialysis.

Digoxin-Like Immunoreactive Factors (DLIF) which cross-react with antidigoxin antibodies are present in elevated concentrations in patients on hemodialysis, uremia, hypertensives, liver failure, pre-eclampsia and premature birth. DLIF may have a potential role as a natriuretic hormone with a speculated low molecular weight (less than 1000). We studied the dialyzability and bindings of DLIF with serum components in hemodialysis patients. We analyzed DLIF concentrations in sera and protein free ultrafiltrates of 31 patients and 22 normal volunteers using a fluorescence polarization assay for digoxin. The DLIF concentrations were expressed as nmol/L Digoxin Equivalent. The gel filtration analysis was done using three different Bio-Gel columns with molecular weight cut-offs of 10,000, 20,000 and 40,000. Molecules with lower molecular weight than cut-off were absorbed in the column. Only 3 out of 22 normal volunteers (13.6%) showed measurable DLIF. However 23 out of 31 patients (74.2%) showed measurable DLIF. The concentrations of DLIF were significantly higher in patients with renal failure on hemodialysis (P less than 0.05) by both chi-squared and Fisher's exact test. We observed no statistically significant difference in the concentrations of DLIF in pre and post-dialysis sera, indicating that DLIF were not filtered during hemodialysis. We observed no DLIF activity in the protein free ultrafiltrates of any DLIF positive sera (patients and normal volunteers), indicating that unlike digoxin (where we observed 70-80% of total digoxin concentrations in ultrafiltrates), DLIF were strongly bound to serum components. With Bio-Gel filtration experiments (five different serum pools), we recovered all DLIF activities in the fraction equivalent to the void volume of the column with Bio-Gel P6 and P10 columns, indicating that DLIF were almost completely bound to serum components with molecular weight greater than 20,000. On the other hand, we recovered no DLIF activities in the void volume when the same serum pools were passed through the Bio-Gel P30 column, indicating that DLIF were strongly bound to serum macromolecules with molecular weight less than 40,000. In sharp contrast, when serum containing digoxin was subjected to the same series of experiments, we recovered only 20-30% of digoxin concentrations in void volume with all three columns as expected since digoxin is only 25% bound to albumin (MW 67,000).

Blood Proteins↗
PubMed1991

Tunicamycin-resistant variants from five species of Leishmania contain amplified DNA in extrachromosomal circles of different sizes with a transcriptionally active homologous region.

Twelve independent variants were selected from five species of Leishmania for resistance to tunicamycin by exposure of cultured promastigotes to increasing concentrations of this antibiotic, an inhibitor of the microsomal N-acetylglucosamine-1-phosphate transferase in the dolichol pathway of N-glycosylation. All variants obtained from all species, as found previously with Leishmania amazonensis, contain amplified chromosomal DNA exclusively as extrachromosomal circles. These circular amplicons hybridize with amplified DNAs cloned previously from tunicamycin-resistant Leishmania amazonensis, but not with those from Leishmania resistant to other drugs. The amplicons from tunicamycin-resistant cells vary with different species in size from 30 to 70 kb, but all share a homologous region of 20 kb. Multiple independent transcripts are overexpressed from this region. Elevation of the microsomal glycosyltransferase activity is demonstrated in these variants from representative species. The results thus provide further evidence that this enzyme is overexpressed due to amplification of the gene in these cells. The consistent observation of this event in all cases studied also suggests that this is the predominant, if not the only mechanism of tunicamycin resistance in Leishmania.

Animals↗
PubMed1991

Ocular pulse amplitude in myopia.

We studied the ocular pulse amplitude of myopic patients by using Alcon Pneumotonography. One hundred and eighty-eight cases (376 eyes) were enrolled in this study. The results revealed that the higher the myopia the lower the ocular pulse amplitude. The pulse amplitude has high correlation with refractive error and axial length, but poor correlation with scleral rigidity, intraocular pressure and corneal curvature. As the ocular pulse amplitude is generated by the choroidal blood flow, these results may reflect circulatory disturbance in the development of myopia.

Adolescent↗
PubMed1991

Multivariate comparison of the forelimb between stump-tailed and rhesus macaques.

Rhesus macaques and stump-tailed macaques are sympatric in western Yunnan (China), coexisting or occupying habitats that show little difference. This paper tests hypotheses based on theoretical expectation from the differing biomechanical demands of terrestrial and arboreal quadrupedalism in stump-tailed macaques and rhesus macaques, respectively. Individuals of these two macaque taxa were markedly separated by the first two principal components and discriminant analyses based on 18 variables of the upper limb. The rhesus macaques appear to be more adapted for arboreal quadruped habits because of elongation of the clavicle and forearm, a larger humeral head and greater midshaft sagittal diameters of the radius and ulna.

Analysis of Variance↗
PubMed1991

[Chemical constituents of Ipomola batatas Lam].

Three chemical compounds isolated from the leaves and stems of Ipomoea batatas were identified as fumaric acid, succinic acid and 7,3',4'-trimethylquercetin by chemical and spectroscopic analysis. In this paper, an analysis of the amino-acids of Ipomoea batatas is also reported.

Amino Acids↗
PubMed1991

Clinical observations on acupuncture treatment of peripheral facial paralysis aided by infra-red thermography--a preliminary report.

We have carried out clinical observations on 34 patients with peripheral facial paralysis treated by acupuncture therapy prescribed according to selection of treatment regimen on the basis of facial thermogram and temperature. A comparison was made with a control group of 97 patients who received conventional acupuncture therapy only. It was found that 1) The cure rate in the group of selecting acupoints by thermogram (hereinafter referred to as the thermography--aided treatment group) was 67.65%, with a marked improvement rate of 26.40%; while the cure rate of the conventional acupuncture treatment group (hereinafter called the conventional treatment group) was 46.39%, the marked improvement rate being 29.90%, indicating a significant difference in therapeutic efficacy between the two groups (P less than 0.02). 2) The average duration of acupuncture therapy for the thermography aided treatment group was 6.02 weeks, whereas that for the conventional treatment group, 24 weeks. There was also a significant difference between the two groups (P less than 0.01). And 3) During the entire therapeutic course, 25.2 sessions of treatment were given on the average in the thermography--aided treatment group, and 78.8 sessions in the conventional treatment group, showing a very significant difference (P less than 0.001). The present thermography--aided method exhibits advantages over the conventional one in enhancing the cure rate and shortening the duration of treatment, which is worthy to be popularized in clinical practice. And it is also of certain significance in standardization and scientification of acupuncture therapy.

Acupuncture Points↗
PubMed1990

An immunopathologic study of retinoblastoma protein.

We investigated the immunoreactivity of the retinoblastoma protein in eight retinoblastoma tumors of different stages of differentiation. All undifferentiated tumor cells failed to show immunoreactivity. In one patient, who had a family history of retinoblastoma and had been treated by radiation, the tumor had a large area of undifferentiated cells and small independent retinocytomas. The tumor cells in the retinocytoma and the cone cells in the adjacent retina, but not the undifferentiated tumor cells, showed positive staining with two anti-Rb antibodies. The immunoreactivity may be related to radiation or differentiation of retinoblastoma and cone cells.

Child, Preschool↗
PubMed1990

[The comparison of changes of the facial temperature after acupuncturing point of hand and foot-yangming meridians by the thermography].

With thermographic technique, We observed changes of the facial temperature after acupuncturing Hegu (L14) and Zusanli (S36) in 65 patients (103 cases in all) with facial nerve paralysis. The observation showed that the average of Hegu group was higher than that of Zusanli group. The result explained that the effect of acupuncture at points of hand-yangming meridian was bigger than that of foot-yangming meridian on the facial temperature.

Acupuncture Points↗
PubMed1990

[Screening for in vitro metabolites of meisoindigo using RP-HPLC-DAD with gradient elution].

A method of screening for in vitro metabolites of meisoindigo using RP-HPLC-DAD (photodiode array detector) with gradient elution was reported. Meisoindigo, a new structural antitumor agent, was metabolized by rat liver microsomes in vitro. The extract of the metabolic sample was dissolved in MeOH-acetone (9:1). An aliquot of the solution was injected onto a 5 microns YWG-C18 (ODS) column (15 cm X 4.0 mm I D) and separated with H2O (0.05% H3PO4)-MeOH in linear gradient elution. The flow rate was 0.5 ml/min and the oven temperature was 40 degrees C. Two simultaneous monitoring wavelengths (270 and 380 nm) were used in order to avoid detective losses of unknown metabolites. The spectral recording range of chromatographic peaks was set from 220 to 440 nm. After comparison of the chromatograms and the spectra of chromatographic peaks, ten metabolites were screened out which gave similar spectrum. Of them, the main chromatographic peaks (No. 7, 8) were confirmed as two monohydroxy metabolites by EI-MS. Their relative contents were calculated by area normalization method. The experimental results show that this method is characteristic of highly effective separation and specific detection. The whole analytical course can be completed in less than two hours. The effects of different elution models, detective parameters and components of mobile phase on the analytical results were discussed.

Animals↗
PubMed1989

Clastogenicity evaluation of seven chemicals commonly found at hazardous industrial waste sites.

7 chemicals commonly found at the industrial waste sites were tested with the Tradescantia-Micronucleus (Trad-MCN) assay to evaluate their clastogenic potential. Chemicals selected from the US EPA Superfund Priority 1 list were: aldrin, arsenic trioxide, 1,2-benz[a, h]anthracene, dieldrin, heptachlor, lead tetraacetate and tetrachloroethylene. Results of repeated tests for clastogenicity yielded the minimum effective dose (MED) for clastogenicity of 0.44 ppm for lead tetraacetate, 1.88 ppm for heptaclor, 3.81 ppm for dieldrin and arsenic trioxide and 1,2-benz[a, h]anthracene yielded positive responses at the MED of 3.96 ppm and 12.50 ppm respectively. Aldrin and tetrachloroethylene were considered to be immiscible with water, and the tests yielded negative responses. Tetrachloroethylene in gaseous state was also used to treat the flower buds. Results of tetrachloroethylene vapor phase treatment yielded a positive response at the MED of 30 ppm/min after a 2-h exposure. 5 chemicals determined to be clastogens by this test were ranked according to their MED in the descending order of potency as follows: lead tetraacetate, heptachlor, dieldrin, arsenic trioxide and 1,2-benz[a, h]anthracene. Results of this study indicate that the Trad-MCN bioassay could be effectively utilized for assessing the potential clastogenicity of the chemicals commonly found at the industrial hazardous waste sites.

Aldrin↗
PubMed1989

Enkephalin fibers synapse on cholinergic neurons in the rat sacral intermediolateral nucleus: a double-immunostaining at the light and electron microscopic levels.

Relationships between leucine-enkephalin fibers and cholinergic neurons in the rat sacral intermediolateral nucleus were examined by light and electron microscopy using double-immunostaining method. Cholinergic neurons in the sacral intermediolateral nucleus were labeled by a rat-mouse monoclonal antibody to choline acetyltransferase and stained bluish green with 5-bromo-4-chloro-3-indolyl-beta-D- galactoside reaction products using beta-galactosidase as a marker. On the same sections, leucine-enkephalin fibers were labeled by a rabbit polyclonal antiserum to leucine-enkephalin and stained brown by diaminobenzidine reaction products using peroxidase as a marker. After embedding in Epon, the sections were examined in light and electron microscopes. In the light microscope, choline acetyltransferase-like immunoreactive cells were seen in the sacral intermediolateral nucleus. In the same region, leucine-enkephalin-like immunoreactive cells. In the electron microscope, 5-bromo-4-chloro-3-indolyl-beta-D-galactoside reaction products were in the form of coarse electron dense deposits in the choline acetyltransferase-like immunoreactive structures and could be distinguished from the much finer grained diaminobenzidine reaction products. Choline acetyltransferase-like immunoreactive neurons received synaptic inputs from leucine-enkephalin fibers-like immunoreactive terminals. These findings suggest that leucine-enkephalin fibers may affect the activity of cholinergic parasympathetic preganglionic neurons.

Animals↗
PubMed1989

Clinical observations on occlusion myopia.

The authors studied the refractive errors and axial lengths on thirty patients. A retrospective analysis suggests some degree of monocular vision deprivation early in life. Axial myopia was found in most of the cases, indicating that emmetropization is a vision-dependent phenomenon. But, some exceptions were found, supporting the concept that multiple factors are involved in the pathogenesis of myopia.

Adolescent↗
PubMed1988

Direct adrenergic inputs to sacral autonomic neurons: using a double-immunostaining method at the light and electron microscopic levels.

Relationships between adrenergic fibers and cholinergic neurons were examined in the rat sacral intermediolateral nucleus using a double-immunostaining method at light and electron microscopic levels. Adrenergic fibers were immunohistochemically stained brown by peroxidase reaction, and cholinergic neurons in the same sections were stained bluish green by beta-galactosidase reaction. In the light microscope, many cholinergic neurons were seen in the intermediolateral nucleus and some of them were surrounded by adrenergic fibers. In the electron microscope, adrenergic fibers made synapses with the cholinergic neurons in the intermediolateral nucleus. These results suggest that adrenergic fibers directly influence the activity of the sacral parasympathetic preganglionic neurons.

Animals↗