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Biomedical subjects

L Yu

Publications and source records attributed to L Yu.

852 records · Page 48Linked to original sources
PubMedDate not supplied

Molecular characteristics of full-length genomic segment A of three infectious bursal disease viruses in China: two attenuated strains and one virulent field strain.

The full-length cDNA of genomic segment A of three infectious bursal disease viruses, two attenuated strains (HZ2 and JD1) and one virulent field strain (ZJ2000), was amplified in a single step by reverse transcription-polymerase chain reaction, cloned into pGEM-T Easy Vector, and sequenced. The full length of cloned segment A contains 3259 nucleotides, which includes two partially overlapping open reading fragments (ORFs) ORF1 and ORF2, flanked by 5' and 3' noncoding regions. These strains shared high sequence identity with each other either at the nucleotide or deduced amino acid level. Strains HZ2 and JD1 were highly related to two attenuated strains, CEF94 and P2, whereas ZJ2000 was closely related to two other virulent strains, Cu-1 and Harbin. Substitutions of four amino acids at positions 253, 279, 284, and 330, a common feature of attenuated and most virulent strains, were also observed in these three strains. Two major hydrophilic peaks were conserved in the three strains; however, there are two amino acid substitutions at positions 280 (N to S) and 290 (M to L) in the second minor hydrophilic peak for all three strains, which might have a critical influence on antigenicity. Two amino acid substitutions near the VP2-VP4 cleavage site were identified in virulent strain JZ2000, which might be involved in increasing the virulence of the virus. Phylogenetic analyses indicated that these three Chinese strains are most closely related to some European virulent strains but are distinct from very virulent infectious bursal disease virus and variant strains.

Animals↗
PubMedDate not supplied

Disposition kinetics and metabolism of nicotine-1'-N-oxide in rabbits.

The disposition kinetics and metabolism of nicotine-1'-N-oxide (NNO) are of interest as the reduction of NNO might influence the pharmacokinetics of nicotine in tobacco users. The disposition kinetics of nicotine-1'-N-oxide were characterized in New Zealand rabbits. The clearance of NNO averaged 7.5 ml/min/kg. The half-life averaged 42.6 min and VDss was 0.34 liter/kg. The oral and ip bioavailabilities were 15.1 and 79%, respectively. NNO was reduced to nicotine and cotinine following i.v., oral, and ip injection. The pattern of metabolites after iv dosing suggests that there is systemic reduction of NNO, although the magnitude of that reduction is small, with less than 3% reduced to nicotine. Following oral NNO, 45% was reduced, with a metabolite pattern consistent with presystemic (bacterial or intestinal) metabolism.

Administration, Oral↗
PubMedDate not supplied

The menopausal transition: guidelines for researchers.

We believe that the menopausal transition can be eased for women if they have information about normal changes they can anticipate. Until now, research on the subject of menopause has been fragmented and flawed, in large part because an "oppositional approach" to the study of menopause has pitted biology against culture and has slowed progress toward a more fruitful interactive approach. Failure to agree on basic definitions has contributed further to fragmentation. Future research efforts must employ healthy, non-clinical samples and prospective designs that will avoid recall problems. Women must be at the center of this research, as respondents whose experiences and interpretations of these experiences become the focus of study. It is the normalcy of menopause that remains undocumented (Voda & George, 1986). When research has identified a range of experiences common to the menopausal transition for healthy women, it will be possible for aging women and their health care providers to make accurate assessments of their individual patterns of change. It is anticipated that studies will document a wider range of changes as normal than is currently accepted, perhaps reducing the number of interventions occurring when pathology is identified incorrectly. Studies with a bi-directional focus will make possible an understanding of the mutual influences of biology and culture on premenopausal women's changing experiences. Knowledge of which symptoms are inevitable conditions of hormonal shifts and which are not will remove the burden of ignorance from women and empower them to better cope with this life stage.

Female↗
PubMedDate not supplied

Determination of o-phenylphenol, diphenylamine, and propargite pesticide residues in selected fruits and vegetables by gas chromatography/mass spectrometry.

A simple and rapid method was developed to detect o-phenylphenol, diphenylamine, and propargite in selected fruits and vegetables. Gas chromatography/mass spectrometry in the selective-ion monitoring mode was used to identify and quantitate the 3 residues. Residues were extracted with acetonitrile and transferred to acetone. Limits of detection were 10, 8, and 15 ppb for o-phenylphenol, diphenylamine, and propargite, respectively. Recovery data were obtained by fortifying 4 matrixes (apples, oranges, canned peaches, and spinach) at 0.025-0.888 ppm. The method provides very good linearity data with low coefficients of variation.

Biphenyl Compounds↗
PubMedDate not supplied

Dual-parameter model for prediction of type I diabetes mellitus.

The recent cloning and recombinant expression of novel islet autoantigens [glutamic acid decarboxylase (GAD) 65 and islet-cell autoantibody 512 (ICA512)] has made possible the determination of whether the quantitative expression of autoantibodies to these molecules is correlated with age of diabetes onset and rate of progression to diabetes, similar to insulin autoantibodies (IAAs). We measured autoantibodies reacting with GAD65 (GAD65AA), ICA512 (ICA512AA), and insulin in patients who recently had received a diagnosis of diabetes and in first-degree relatives prospectively identified and then followed because of the expression of high titers of ICA. Levels of IAAs (but not GAD65AA or ICA512AA) correlated inversely with age at diagnosis of diabetes and directly with time to diabetes onset among the ICA-positive relatives. In multiple linear regression models, the level of IAAs remained a significant predictor of the time to diabetes after allowing for first-phase insulin secretion. The unique and dramatic association of IAAs with progression to diabetes suggests that IAAs contribute directly to disease pathogenesis or that levels of IAAs are influenced uniquely by the process, leading--at different rates in different prediabetic individuals--to type I diabetes. In addition, the linear regression model described (involving two variables, first-phase insulin secretion and levels of IAAs) aids in the prediction of time to diabetes among ICA-positive relatives.

Adolescent↗