Search PubMed⌕ Search

Biomedical subjects

Y Du

Publications and source records attributed to Y Du.

At least 199 records · Page 11Linked to original sources
PubMed1993

Effect of CCK-8 on audiogenic epileptic seizure in P77PMC rats.

P77PMC rat is a breed of rat with congenital audiogenic seizure(AS). AS attacks were suppressed by cholecystokinin octapeptide (CCK-8) injected intraperitoneally (i.p.) at a dose of 50 micrograms/kg, but not at 25 micrograms/kg. Radioimmunoassay study showed that the CCK-8 immunoreactivity (IR) in the cerebrocortex and hippocampus is much lower in P77PMC rats than that of Wistar rats. The results suggest that a low cerebral content of CCK-8 may account for the high susceptibility of audiogenic seizure in P77PMC rats.

Acoustic Stimulation↗
PubMed1993

Adsorption of Na+ onto gamma-alumina studied by solid-state 23Na and 27Al nuclear magnetic resonance spectroscopy.

The adsorption of Na+ on gamma-alumina surfaces at four coverages of Na2CO3[5, 10, 15 and 20% w/w)] was characterized by solid-state 23Na and 27Al nuclear magnetic resonance (NMR) spectroscopy. The experimental results suggest that two distinct adsorbed species are present on the alumina surface: surface species and surface salts. At the lower coverages of Na2CO3 (5 and 10%), the surface species is predominant, in which the Na+ cations are associated with the oxygen atoms of gamma-alumina. Increasing the loading level to 15% results in the appearance of a second adsorbed species that is attributed to the surface salt, Na2CO3, deposited on the solid surface. Further adsorption of Na2CO3 leads to an increase in the amount of surface salt while the amount of surface species remains unchanged. 1H-27Al Cross-polarization magic angle spinning (CP-MAS) experiments give the evidence that some Na+ cations in the form of surface species are coordinated with the Brönsted acid sites of gamma-alumina. This may be the main driving force that improves appreciably the catalytic efficiency of an Na2CO3-Al2O3 catalyst.

Adsorption↗
PubMed1993

Solid-state NMR studies of 1H spin diffusion in adsorbed organic molecules.

1H spin diffusion times of toluene (MB) and tetrahydrofuran (THF) adsorbed on a series of porous solids (charcoal, SiO2 and Al2O3) were measured by a selective inversion technique. The experimental results show that they cover a wide range (from less than one millisecond to several hundreds of milliseconds). For all samples, a tri-exponential behavior was observed in the magnetization recovery processes of the negative peaks. This is attributed to the existence of the two different kinds of spin diffusion processes in addition to the T1 relaxation. One is assigned to the intermolecular spin diffusion between the surface acidic protons of the adsorbent and the organic molecules adsorbed on the solid surface, the other to the intramolecular spin diffusion of adsorbed molecules. Due to hydrogen bonding between the surface hydroxyl groups and the adsorbate, the intermolecular spin diffusion of THF adsorbed on various solids is more effective compared to that of adsorbed MB. In addition, the intermolecular 1H spin diffusion between charcoal and adsorbed THF molecules was confirmed by indirect measurement suggested by Tekely et al.

Charcoal↗
PubMed1993

Contrast-to-noise-ratio measurements in three-dimensional magnetic resonance angiography.

RATIONALE AND OBJECTIVES: The authors report on the development and preliminary validation of a technique for measuring contrast-to-noise ratio (CNR) at all points along selected vessel segments in the original three-dimensional magnetic resonance angiography (MRA) dataset. METHODS: Contrast-to-noise ratio dependencies on flow rate, field of view, and flip angle were measured on images from a conventional time-of-flight MRA pulse sequence using constant flow in a branching vascular phantom. An estimate of the inherent variability of the technique was obtained from multiple scans of a flow phantom and a human volunteer. RESULTS: The overall standard deviation (SD) of the CNR was found to be approximately 6.1% of the average CNR value for the flow phantom study and 7.3% for the human study. Vessel CNR was found to increase with field of view and was found to become nonuniform for low flow rate and/or high flip angles. CONCLUSION: In general, such CNR measurements allow the investigation of the mechanism of signal loss and general technique optimization in MRA.

Blood Vessels↗
PubMed1993

Characterization of a rabbit fast skeletal troponin I cDNA: a comparative sequence analysis of vertebrate isoforms and tissue-specific expression of a single copy gene.

A cDNA encoding skeletal fast troponin I (TnIf) has been isolated and characterized from an adult rabbit fast skeletal muscle cDNA library. This cDNA contains the entire coding region of 549 base pairs (bp), the 3' untranslated (UT) segment of 78 bp and the 5' UT segment of 74 bp. The 3' UT segment shows the predicted stem-loop structure characteristic of eukaryotic mRNAs. The cDNA-derived amino acid sequence is not identical to the chemically-derived and the recently reported cDNA-derived amino acid sequences for rabbit TnIf, and thus enables to make the necessary corrections in the sequence information. The rabbit TnIf is encoded by a single copy gene which is expressed in adult fast skeletal muscle in a tissue-specific manner. Comparative sequence analysis of the vertebrate TnI isoforms and their cDNAs shows a high level of sequence conservation in the coding region among the TnIf interspecies isoforms. The sequence similarity is markedly decreased among the fast, slow and cardiac intra- and inter-species isoforms. The C-terminal halves of TnI isoforms including a segment believed to be involved in critical interactions with actin and troponin C (TnC) show high sequence conservation whereas the N-terminal halves show considerable difference in sequence and size. The significance of these results in relation to the biological function and evolution of members of the vertebrate TnI multigene family is discussed.

Amino Acid Sequence↗
PubMed1993

[Morphological study on acupuncture in interfering experimental cerebral infarction in rat. I. Compensation of cerebral PIA mater artery in cerebral surface].

Occluding unilateral middle cerebral artery (MCAo) of rat, the compensatory blood vessels (CBV) within ischemic area in cerebral surface shown by cerebral perfusion and effect of acupuncture were observed dynamically. Perfusing immediately after MCAo, there was no any blood vessel in the ischemic area. In acupuncture group, the CBV had extended a lot from anastomotic network of cerebral pia mater (ACA-MCA, PCA-MCA) located in marginal zone of ischemic area 3 hs after MCAo. 6.24 and 48 hs after MCAo, the CBV increased much more than control group (non-acupuncture) P < 0.01. The experiment pointed out that there existed a serious vasospasm in the MCA system in initial stage of MCAo, which led up to decompensation in the ischemic area. The acupuncture can remit the vasospasm, and reverse the deteriorated process in early.

Acupuncture Therapy↗
PubMed1992

A mutation in the POU-homeodomain of Pit-1 responsible for combined pituitary hormone deficiency.

Pit-1 is a pituitary-specific transcription factor responsible for pituitary development and hormone expression in mammals. Mutations in the gene encoding Pit-1 have been found in two dwarf mouse strains displaying hypoplasia of growth hormone, prolactin, and thyroid-stimulating, hormone-secreting cell types in the anterior pituitary. A point mutation in this gene was identified on one allele in a patient with combined pituitary hormone deficiency. Mutant Pit-1 binds DNA normally but acts as a dominant inhibitor of Pit-1 action in the pituitary.

Alleles↗
PubMed1992

Effects of N-acetylcysteine on diaphragmatic function and malondialdehyde content in Escherichia coli endotoxemic rats.

We evaluated the effects of sublethal Escherichia coli endotoxemia with or without concomitant administration of N-acetylcysteine, an antioxidant agent, on diaphragmatic strength, endurance, and malondialdehyde (MDA) content in rats. One hundred ninety rats were inoculated subcutaneously on 2 successive days with 0.6 and 1.2 mg/100 g body weight of E. coli lipopolysaccharide respectively (E animals, n = 100) or saline (C group, n = 90). E and C animals were divided into two groups based on administration of endotoxin or saline alone (E group, n = 55; C group, n = 47, respectively) or endotoxin or saline plus N-acetylcysteine (1 g/kg body weight/day intraperitoneally) (E-NAC group, n = 45; C-NAC group, n = 43, respectively). Diaphragmatic strength was assessed in vivo 48 h after the first endotoxin or saline administration by measuring the transdiaphragmatic pressure (Pdl) generated during electrical stimulation of the phrenic nerves at 0.5, 10, 20, 30, 50, and 100 Hz. Endurance index was calculated as the percent ratio of Pdl generated after 30 s of phrenic stimulation at 10 Hz divided by the initial force. Diaphragmatic MDA (fluorometric technique) was measured 0, 6, 18, 30, 42, and 48 h after the first dose of endotoxin or saline. Pdl for 50 and 100 Hz was significantly reduced in Group E as compared with group C. This phenomenon was associated with a reduced endurance performance as assessed by a lower diaphragmatic endurance index in E as compared with C animals (90.9 +/- 4.2 versus 114.3 +/- 4.1 respectively; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcysteine↗
PubMed1992

The cytoplasmic translational inhibitory RNA of chick embryonic muscle: cloning and sequence of a subspecies which is antisense RNA.

A cytoplasmic translation inhibitory ribonucleoprotein (iRNP), about 10-12S in size and containing a heterogeneous class of RNA (iRNA) in the 60-140 nucleotide size range, has been previously isolated from 13-14 day old chick embryonic leg and breast muscle. Both iRNA and iRNA are potent inhibitors of mRNA translation in vitro. A cDNA library for iRNA was prepared in pUC18 vector. The 114 nucleotide insert of one clone was subcloned in pBluescript vector. The in vitro transcript of this insert (only the 5'-3' orientation and not the reverse orientation) showed inhibition of muscle poly(A)+ mRNA translation in vitro. The derived sequence of the iRNA indicates that it is a new sequence in which 27 nucleotides at the 3' and 5' ends can form base paired stem. Hybridization experiments and sequence analysis indicate that this iRNA has complementary (antisense) sequence to a highly conserved domain of the 28S eukaryotic rRNA and to a 5' leader segment of a muscle mRNA. These results suggest that iRNA mediated translational inhibition may act as a novel mechanism of controlling cellular mRNA levels in embryonic muscle and thus, acts in conjunction with the transcriptional control of myogenesis.

Animals↗
PubMed1990

[DNA polymorphisms and haplotypes in the apoAI-CIII gene region and coronary heart disease].

Polymorphisms and haplotypes identified by DNA Restriction Fragment Length Polymorphisms in the apoAI-CIII gene region were investigated both in 33 Chinese patients with coronary heart disease and 50 unrelated healthy subjects, using genomic DNA hybridization analysis with a 1.0 kb fragment of the human apoAI gene cDNA. The frequencies of the S2 and M2 alleles were 0.167 and 0.22 in healthy subjects, 0.11 and 0.24 in patients respectively. There were no differences in the frequencies of the S2 and M2 alleles between patients and healthy subjects. Since none of the subjects had the genotypes, S1S2M1M1, S2S2M1M2 and S2S2M1M1, all of the S2 alleles were considered to be associated with the M2 alleles at least in Chinese population. The alleles identified by the apoCIII Sst-I and apoAI Msp-I polymorphisms are in linkage disequilibrium. The individuals with the haplotype S1-M2 were significantly increased in patients compared with the ones in healthy subjects (26% versus 4.6%; chi 2 = 6.91, d.f = 1, P less than 0.01). The results of the present study suggest that both the apoCIII Sst-I and apoAI Msp-I polymorphisms may be a useful genetic marker for the analysis of apoAI-CIII gene complex and the haplotype S1-M2 may be a useful linkage marker for the putative atherogenic gene in Chinese.

Apolipoprotein A-I↗
PubMed1990

[Effect of hyperthermal environment on urinary excretion of beta 2-microglobulin and hydrogen ion].

By randomized sampling, 1387 cases working in various circumstances in Chengdu Seamless Steel Tube Plant had their urine net acid clearance (NAC) and osmotic pressure (OSMP) measured, of whom 407 took urine beta 2m examination in addition. Results show that both NAC and OSMP are much higher in the hyperthermal group than in the non-hyperthermal group. There is no significant difference in beta 2m level between the two groups, which demonstrates that the function of proximal renal tubules of the workers in this plant has not been affected, as their working condition conforms to the standards for the prevention of workers made by the government. However, the beta 2m level in the male workers is obviously higher than that in the female. There exists the possibility that the males have contacted the toxic dust at a longer duration, which may be a factor involved in the tubular disorder. The rise of beta 2m together with age is regarded as due to senile decay. This study has provided available data for the set up of worker's prevention system.

Adult↗
PubMed1990

[Various methods for purification of urine Tamm-Horsfall protein].

The measurements of serum, urine Tamm-Horsfall protein (THP) and its antibody are essential to the early diagnosis of tubulointerstitial diseases and acute rejection after renal transplantation. The purification of THP proves to be the key procedure for the production of diagnostic kit. Once, twice and three times salt precipitation with 0.58 mol/L NaCl and chromatography with Sephadax G-200 were adopted to purify urine THP. Enzyme immunoassay was used to detect the antigenicity of the products, SDS-PAGE to determine the molecular weight (MW) and the electrophoretic purity (EP), Beckman DU-7 model spectrophotometer to scan the ultraviolet absorption spectrum. Evaluation of the four methods was based on the purity and the antigenicity of the produced THP, the output, the complexity of procedure, and the cost of required materials. Results show that the MW of THP is 93.0 kd; the ultraviolet absorption maximum is at lambda = 278 nm; the outputs are 7.5, 5.5, 3.8, and 0.4 mg/L; the concentrations of THP with antigenicity are 65%, 75%, 98% and 100%, respectively, and the EPs of three times salt precipitation and chromatography are better. It is concluded that three times salt precipitation should be recommended because of its excellence in purity and antigenicity of the produced THP, the simplicity of manipulation, and the cheapness of the materials needed.

Humans↗