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Biomedical subjects

Y Lei

Publications and source records attributed to Y Lei.

At least 19 recordsLinked to original sources
PubMed2007

Effect of acute gastric electrical stimulation on the systemic release of hormones and plasma glucose in dogs.

This study evaluated the effect of gastric electrical stimulation (GES) with various parameters on plasma concentrations of satiety-related peptides and glucose. GES was performed in nine healthy dogs via electrodes implanted in the middle of the lesser curvature. Four sessions were performed in each animal: control, stimulation with IGS (implantable gastric stimulation for obesity, 0.3 m sec), modified IGS (2 msec), and long pulses (300 msec). Blood samples were collected at 15 and 0 min before the meal and at 15, 30, and 60 min after the meal. GES was initiated 30 min before the first blood sample and maintained throughout collection. Plasma ghrelin, leptin, insulin and glucose were measured. The total AUCs of plasma ghrelin and leptin were not significantly affected by GES. The total AUC of plasma insulin was significantly lower with IGS and long pulse parameters (P < 0.05). The total AUC for plasma glucose was significantly lower in sessions with long pulses and modified IGS parameters (P < 0.05). We conclude that acute GES is able to change the release of some satiety-related peptides. Whether this is associated with the changed eating behavior and weight loss in obese patients needs further investigation.

Animals↗
PubMed2006

Prevalence of factor V Leiden and prothrombin G20210A mutations in Chinese patients with deep venous thrombosis and pulmonary embolism.

Venous thromboembolism (VTE) is a common vascular disease that results in two major clinical manifestations: deep venous thrombosis (DVT) and pulmonary embolism (PE). Several genetic risk factors, especially factor V Leiden and prothrombin G20210A mutations have been reported to be related to VTE in Caucasians, but the relationship remains controversial in other populations. Thus, the objective of the present study was to compare the frequency of the two mutations and also to investigate whether acquired risk factors other than genetic mutations may play a different role in Chinese VTE patients. Thirty-five patients were diagnosed with DVT concomitant PE, 178 patients with DVT, 54 patients with PE and 102 control subjects were recruited. The mutation was determined by the polymerase chain reaction-restriction fragment length polymorphism method. Of all subjects, none was a carrier of factor V Leiden or prothrombin G20210A mutations. The frequency of surgery was significantly higher in the PE group than that in other groups. There was no significant difference among the three groups in other known risk factors. The data presented here indicate that factor V Leiden and prothrombin G20210A mutations are very rare in the Chinese population, and the genetic risk profile of VTE in the Chinese population is different from that in Caucasians.

Adult↗
PubMed2005

Dynamic changes in orbitofrontal neuronal activity in rats during opiate administration and withdrawal.

The orbitofrontal cortex is involved in the reinforcing effects of drugs of abuse. However, how the dynamic activity in OFC changes during opiate administration and withdrawal period has not been investigated. We first tested the effects of opiates and drug craving with the conditioned place preference paradigm, using manganese-enhanced magnetic resonance imaging and traditional electroencephalograph recording techniques in rats. T1-weighted 2D MRI (4.7 T) was used after unilateral injection of MnCl(2) (200 nL, 80 mM) into the right orbitofrontal cortex. The manganese-enhanced magnetic resonance imaging data suggested that the OFC activity decreased during the opiate administration period but recovered increasingly during the withdrawal period. Also, we found decreases and increases in gamma-band (20-100 Hz) activity during the opiate administration and withdrawal period, respectively. Our results showed that orbitofrontal cortex activity decreased during morphine administration and then went up progressively over several days during withdrawal. The time course of the recovery of orbitofrontal activity from inhibition during the withdrawal period may be related to the experience of drug craving.

Animals↗
PubMed2005

Subcellular fractionation and molecular characterization of the pellicle and plasmalemma of Neospora caninum.

A characteristic structural feature of Toxoplasma gondii and Neospora caninum is the presence of a triple-membrane pellicle, on the zoite stages of their complex life-cycle. Here we report the results of electron microscopic studies which show that the pellicle is made of a typical plasmalemma covered on its cytoplasmic side by a system of flattened vesicles named the inner membrane complex. Using methods described previously for the purification of pellicle and plasmalemma fractions from T. gondii, we have evaluated the same methodology for the preparation of pellicles and plasmalemma from N. caninum. The approach used involved subcellular fractionation and sucrose gradient centrifugation to prepare fractions containing pellicles. Plasmalemma was prepared by extraction of this fraction with a high salt glycerol treatment. Fractions containing membrane structures were identified by electron microscopy, and the proteins and antigens present in them were subsequently studied by SDS-PAGE and Western blotting. Electron microscopy of the pellicle fractions of N. caninum demonstrated preservation of the triple-membrane structure which is identical to that found in T. gondii. SDS-PAGE of the pellicle fractions revealed it contained several major proteins. Analyses revealed that the plasmalemma of N. caninum contained 2 abundant proteins in addition to other much lower abundance antigens detectable by monoclonal antibodies. These studies therefore report, for the first time, a detailed molecular characterization of the pellicle and plasmalemma of N. caninum.

Animals↗
PubMed2005

Gastric electrical stimulation (GES) with parameters for morbid obesity elevates lower esophageal sphincter (LES) pressure in conscious dogs.

BACKGROUND: Treatment of obese patients with the implantable gastric stimulator (IGS) was reported to improve reflux symptoms, independent of weight loss. We evaluated the effect of gastric electrical stimulation on LES pressure in conscious dogs. METHODS: 8 dogs were studied. GES with three sets of parameters was randomly applied via a pair of electrodes implanted in the fundus on separate days. Manometry was performed with a Dent-Sleeve catheter passed through an esophageal canula. The involvement of the cholinergic pathway was also tested. RESULTS: 1) Stimulation with IGS parameters (40 Hz, 0.3 ms, 6 mA, 2 seconds on and 3 seconds off) induced a significant increase in LES pressure (29.9+/-4.8 mmHg), and remained significantly higher during the post-stimulation period (32.6+/-9.6 mmHg) compared to baseline (24.5+/-3.8 mmHg), P<0.01.2) Long pulse stimulation (10 cpm, 300 ms, 8 mA) tended to increase LES pressure from 29.6+/-4.4 mmHg of baseline to 31.8+/-4.9 mmHg with stimulation, to 32.6+/-4.5 mmHg after discontinuation (P=0.08); 3) Modified IGS parameters (40 Hz, 2 ms, 6 mA, 2 seconds on and 3 seconds off) did not induce a significant change in LES pressure during and after stimulation. 4) Effect of stimulation with IGS parameters on LES pressure was blocked by intravenous atropine. CONCLUSION: GES with IGS parameters significantly increases LES pressure in conscious dogs. This effect is mediated by the cholinergic pathway. These results suggest that GES may be able to benefit GERD patients and obese patients with GERD.

Animals↗
PubMed2004

Plant growth: the translational connection.

The TOR (target of rapamycin) pathway is a phylogenetically conserved transduction system in eukaryotes linking the energy status of the cell to the protein synthesis apparatus and to cell growth. The TOR protein is specifically inhibited by a rapamycin-FKBP12 complex (where FKBP stands for FK506-binding protein) in yeast and animal cells. Whereas plants appear insensitive to rapamycin, Arabidopsis thaliana harbours a single TOR gene, which is essential for embryonic development. It was found that the product of this gene was capable of binding to rapamycin and yeast FKBP12. In-frame fusion with a GUS reporter gene shows that the TOR protein is produced essentially in proliferating zones, whereas the TOR mRNA can be detected in all organs suggesting a translational regulation of TOR. Phenotypic analysis of Arabidopsis TOR mutants indicates that the plant TOR pathway fulfils the same role in controlling cell growth as its other eukaryotic counterparts.

Gene Expression Regulation, Plant↗
PubMed2003

Microencapsulation and culture in vitro of rat pinealocytes.

BACKGROUND: Melatonin is a powerful anti-aging reagent for scavenging free radicals. However, the effect of exogenous melatonin on age-dependent diseases is uncertain. Immune rejection has limited xenotransplantation or allotransplantation of the pineal gland. The aim of this study was to assess cell viability and the function of rat pinealocytes encapsulated in APA capsules and offer experimental suggestions for pineal microencapsulation grafting to resist aging. METHODS: The pineal glands of neonatal rats were removed. Pinealocytes were isolated and encapsulated in APA microencapsulation and cultured. Morphological appearance of the microencapsulation was observed. Trypan blue staining and 5-HT immunocytochemical assay were used to detect cell viability and identify pinealocytes. The expression of AA-NAT mRNA was confirmed by RT-PCR. Melatonin release was measured and compared by HPLC. RESULTS: Both control and encapsulated pinealocyte cultures survived well. The majority of the encapsulated pinealocytes as well as unencapsulated cells remained 5-HT positive. No significant difference in melatonin secretion and the expression level of AA-NAT mRNA between encapsulated and unencapsulated pinealocytes was found. CONCLUSIONS: Pinealocytes survive and remain functionally competent in vitro at least 2 weeks after microencapsulation.

Alginates↗
PubMed2003

Effect of lipase inhibition on gastric emptying of, and the glycemic and incretin responses to, an oil/aqueous drink in type 2 diabetes mellitus.

This study examined the effects of the lipase inhibitor, orlistat, on gastric emptying of, and the glycemic and incretin hormone responses to, a drink containing oil and glucose components in patients with type 2 diabetes. Seven patients (aged 58 +/- 5 yr), managed by diet alone, consumed 60 ml olive oil (labeled with 20 MBq (99m)Tc-V-thiocyanate) and 300 ml water containing 75 g glucose (labeled with 6 MBq (67)Ga-EDTA), on two occasions, with and without 120 mg orlistat, positioned in the left lateral decubitus position with their back against a gamma camera. Venous blood samples, for measurement of blood glucose and plasma insulin, glucagon-like peptide-1 and glucose-dependent insulintropic polypeptide were obtained immediately before, and after, the drink. Gastric emptying of both oil (P < 0.001) and glucose (P < 0.0005) was faster after orlistat compared with control. Postprandial blood glucose (P < 0.001) and plasma insulin (P < 0.05) were substantially greater after orlistat compared with control. In contrast, plasma glucagon-like peptide-1 (P < 0.005) and glucose-dependent insulintropic polypeptide (P < 0.05) were less after orlistat. In conclusion, inhibition of fat digestion, by orlistat, may exacerbate postprandial glycemia, as a result of more rapid gastric emptying and a diminished incretin response.

Autonomic Nervous System↗
PubMed2002

Enzymatic hydrolysis of waste sugarcane bagasse in water media.

Enzymatic hydrolysis of natural cellulose such as sugarcane bagasse is usually carried out in a buffer medium. In this paper, the enzymatic hydrolysis of a waste sugarcane bagasse in water media was carried out.The bagasse was pre-treated with heating explosion and pure (ion exchange), reverse-osmosis and tap water media were used in place of a buffer solution in the hydrolysis process. The yields for reducing sugars and the changes in solution pH and electric conductivity during the hydrolysis under various conditions were studied. The results were also compared with those obtained in buffer solutions. Similar levels of sugar yields were obtained in water and buffer solution media. The pH of the hydrolyzate was in the range of 4.5 - 5.0, which coincided with the optimum pH for the enzyme reaction. It was considered that the enzyme and the substrate formed a transitional complex in the hydrolysis process. The transitional complex provided the buffering capacity pH 5. The results indicate of the hydrolyzate solution at around that industrialization of the enzymatic hydrolysis in a water medium is feasible.

Cellulose↗
PubMed2001

Hyper immunoglobulin E response in mice with monoclonal populations of B and T lymphocytes.

A key event in the pathogenesis of allergies is the production of antibodies of the immunoglobulin (Ig)E class. In normal individuals the levels of IgE are tightly regulated, as illustrated by the low serum IgE concentration. In addition, multiple immunizations are usually required to generate detectable IgE responses in normal experimental animals. To define the parameters that regulate IgE production in vivo, we generated mice bearing monoclonal populations of B and T lymphocytes specific for influenza virus hemagglutinin (HA) and chicken ovalbumin (OVA), respectively. A single immunization of the monoclonal mice with the cross-linked OVA-HA antigen led to serum IgE levels that reached 30-200 microg/ml. This unusually high IgE response was prevented by the infusion of regulatory alpha/beta CD4(+) T cells belonging to both CD25(+) and CD25(-) subpopulations. The regulation by the infused T cells impeded the development of fully competent OVA-specific effector/memory Th2 lymphocytes without inhibiting the initial proliferative response of T cells or promoting activation-induced cell death. Our results indicate that hyper IgE responses do not occur in normal individuals due to the presence of regulatory T cells, and imply that the induction of regulatory CD4(+) T cells could be used for the prevention of atopy.

Animals↗
PubMed2001

Singularities in the Boussinesq equation and in the generalized Korteweg-de Vries equation.

In this paper, two kinds of analytic singular solutions (finite-time and infinite-time singular solutions) of two classical wave equations (the Boussinesq equation and a generalized Korteweg-de Vries equation) are obtained by means of the improved homogeneous balance method and a nonlinear transformation. The solutions show that special singular wave patterns exist in the classical models of shallow water wave problem.

Journal Article↗
PubMed2001

The sequence of the human genome.

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

Algorithms↗
PubMed2001

The influences of NO and Ach on cGMP levels in two patient populations.

Pulmonary hypertension following cardiac surgery is an important factor affecting postoperative mortality, and its mechanism has not been thoroughly clarified. Cardiopulmonary bypass (CPB) can destroy pulmonary endothelium and aggravate pulmonary hypertension. This study is designed to investigate the impacts of CPB on vascular endothelium-dependent relaxation, and the relations of CPB to pulmonary hypertension. Forty patients undergoing valve surgery were involved. According to their preoperative pulmonary arterial pressure (PAP), these patients were divided into pulmonary hypertension group (H group) and normal group (N group). The concentrations of cyclic guanosine monophosphate (cGMP) were measured at baseline conditions, after acetylcholine (Ach) injection, and during nitric oxide (NO) inhalation. Samples were taken before sternotomy and after weaning from CPB, 4 and 12 hours post-CPB. At baseline, the level of cGMP in the H group was lower than that of the N group by 33.9% before CPB. After initiating the CPB, although the level of cGMP continuously decreased in both groups until weaning from CPB (the N group decreased 33.3%, and the H group decreased 59%). At that point cGMP was higher in N group than in the H group (p < .01). The level of cGMP of both groups tended to recover 4 hours after CPB, but only the N group returned to baseline 12 hours after CPB. After injection of Ach, the level of cGMP of both groups followed the same change as in the baseline, except with different numeric value. The level of cGMP in N group rose ranging from 160.0-197.3%, while it rose ranging from 87.7-168.1% in H group. The levels of cGMP were higher in N group than those in H group at all times following injection of Ach (61.4, 173.3, 202.7, and 188.0%) (p < .01). After inhalation of NO, the level of cGMP of both groups followed the same change as the baseline. The level of cGMP in N group rose ranging from 194.8-320.5%. Although the levels of cGMP were higher in N group than those in H group (6.9, 25.3, 23.3, and 16.6%), significant differences were achieved at the 4 and 12 hour post-CPB periods (p < .05 or p < .01, respectively). It was concluded that the injury of vascular endothelial function caused by CPB was more critical in pulmonary hypertension patients.

Acetylcholine↗
PubMed2001

[Color measurements of 1,944 anterior teeth of people in southwest of China-discreption].

OBJECTIVE: To study the color distribution space of natural anterior tooth crowns of people in southwest China and effects of sex and age on tooth color. METHODS: The subjects studied consisted of 162 persons aged from 20 to 73 years and born in southwest China. A total of 1,944 healthy anterior teeth were measured in-vivo with a fiber-optical spectrophotometry system. RESULTS: Statistical analysis showed that the color distribution space of Chinese tooth crowns was wide. The value of L* varied from 42.383 to 67.428, the value of a* from -4.750 to 1.371, the value of b* from 1.88 to 20.268, the value of x from 0.298 to 0.393, the value of y from 0.332 to 0.392, and the value of Y from 19.383 to 34.025. The color difference between the upper and lower limits of 95% confidence was 31.667 CIE delta E units. The difference in colorimetry between male and female was not significant. The results showed that in three sections of teeth (incisal, middle and cervical) the values of L* and a* were negatively related to age (r < 0, P < 0.01); the value of b* was positively related to age just at the cervical and middle sites of teeth (r > 0, P < 0.01) and was not related to age at the incisal site of teeth (P > 0.05). CONCLUSION: The color distribution space of Chinese anterior tooth crowns is wide. There is no difference in the anterior tooth color between male and female subjects. The values of L* and a* and negatively related to age except the value of b*.

Adult↗
PubMed2001

[A study on the resistance of Staphylococcus aureus and the mechanisms of its resistance to fluoroquinolone].

OBJECTIVE: To investigate the resistance of Staphylococcus aureus(SA) and the mechanisms of its resistance to fluoroquinolones (FQ). METHODS: The susceptibility of SA (200 strains) to 12 antibiotics was detected by disc diffusion, The minimal inhibitory concentrations (MICs) of 52 strains to three FQ were determined by agar dilution method. 52 strains resistant to ciprofloxacin (MIC> or =4 mg/L) were studied for the presence of point mutations in the gyrA gene and grlA gene by polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP) method and for the expression of norA gene by reserpine reverse test respectively. RESULTS: 34% of the strains were resistant to oxacillin(methicillin resistant Staphylococcus aureus, MRSA) and other antimicrobials as well, but no vancomycin resistant strain was found. The resistance rate of MRSA to ciprofloxacin was 79.4% and cross-resistance existed. It was found that 42 strains (80.8%) had a mutation at gyrA codon 84 (TCA-->TTA or GCA). Mutations at grlA codon 80 (TCC-->TAC or TTC) and codon 84 (GAA-->AAA)were observed in 10 (19.2%) and 14 strains(26.9%) respectively.Strains containing mutations in gyrA or both gyrA and grlA gene showed a higher level of ciprofloxacin resistance than those with alternation in grlA gene but with wild type gyrA or non-gyrA mutants (P < 0.01). Decreased MICs to ciprofloxacin, norfloxacin and levofloxacin in reserpine reverse test indicated the presence of norA phenotype. CONCLUSIONS: It is clear that emergence of resistant SA strains will continue to be a problem, especially in MRSA which was resistant to most of the antibiotics. Fluoroquinolones are not the choice for MRSA now. The resistance to fluoroquinolones in clinical isolates of SA are due to the mutations of the gyrA and grlA gene encoding the target enzyme of fluoroquinolones and cell membrane resistance. Mutations of grlA gene may differ in different districts.

Anti-Infective Agents↗
PubMed2001

[Technical causes of false and inferior species appearing in Chinese medicinal materials markets].

The result indicated that technical causes of false and inferior appearing in the Chinese medicinal materials markets consisted of two respects essentially. First, the men who violated the law and committed a crime used certain weak link existing in quantity analysis of country's medicinal standard. Second, it is difficult that basic units managing and using drug implement effective technical supervision.

Drugs, Chinese Herbal↗
PubMed2000

The Drosophila Lissencephaly1 (DLis1) gene is required for nuclear migration.

Nuclear movement is critical for several developmental processes in eukaryotes. Drosophila oogenesis provides a paradigmatic example in which localization of the nucleus generates a source of cellular asymmetry that is used in patterning both the anterior-posterior and the dorsal-ventral axes of the oocyte. In this study we show that mutations in the Drosophila Lissencephaly1 (DLis1) gene result in partial ventralization of the eggshell. DLis1 mutations affect the localization of gurken mRNA and protein in the oocyte. These defects are correlated with incorrect positioning of the oocyte nucleus, suggesting that DLis1 is required for nuclear migration. DLis1 shows significant sequence conservation across the evolutionary spectrum. Fungal cognates of DLis1 are involved in nuclear migration while homologs in humans and mice are implicated in neuronal migration. DLis1 shows genetic interactions with the Glued and Dynein heavy chain subunits of the dynein/dynactin complex, supporting the idea that the Lis1 family of proteins plays a role in microtubule motor-based nuclear motility.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗