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Biomedical subjects

Y Lavi

Publications and source records attributed to Y Lavi.

5 recordsLinked to original sources
PubMed2005

Genetic variation in major histocompatibility complex class I alpha2 gene among broilers divergently selected for high or low early antibody response to Escherichia coli.

The MHC genes have a profound effect on animal abilities to respond to specific antigens because they play a role in presenting foreign antigens to T cells during the course of the humoral or cellular immune response. In the current study, polymorphism in the MHC class I alpha2 domain was compared in 2 lines divergently selected for high (HH) or low (LL) antibody response to Escherichia coli vaccine. These lines also differ markedly in their antibody response to natural E. coli exposure and to vaccination with Newcastle disease virus, infectious bronchitis virus, and infectious bursa disease virus. Recent trials have shown that the LL chicks exhibit a significantly higher percentage of CD8+ T lymphocytes in their peripheral blood lymphocytes and spleen than HH chicks. Despite symmetrical selection intensity in both lines, polymorphism of the alpha2-domain gene was higher in the LL line than in the HH line. Among 29 single-nucleotide polymorphism positions found, 3 were unique to the HH line, 15 were unique to the LL line, and 11 were polymorphic in both lines. These single nucleotide polymorphism positions were not 100% line specific and were in agreement with the genetic variation in antibody level or cellular response still found within the selection lines. Five amino acid positions showed significant differences in polymorphism between the selection lines. These were located within the antigen-binding cleft, suggesting that these positions might influence the ability of MHC class I to bind foreign antigens and leading to differences in immunocompetence between the lines.

Amino Acid Sequence↗
PubMed1991

Assessment of emergency medicine: a comparison of an experimental objective structured clinical examination with a practical examination.

An emergency medicine and trauma programme was implemented at Ben Gurion University Medical School in Israel. Clinical performance assessment of the first-year course in emergency medicine and trauma was done using a practical examination (PE). In the continuous process of critically reviewing the course objectives and assessment methods the objective structured clinical examination (OSCE) was chosen, for the first time in our medical school, as a tool for course development as well as evaluation of the existing PE. Seven experimental OSCE stations were designed which covered some of the course and practical examination topics. Twenty-six first-year medical students have taken both examinations concurrently. Twenty-three students answered an attitude questionnaire regarding both examinations. Results have indicated that the OSCE provided additional and crucial information on students' deficiencies in clinical performance which were not available from the PE. Those differences were probably due to realistic OSCE station content, highly simulated set-ups, and the objectivity of the examiner, all of which have contributed to a more challenging examination, as compared to the PE. The OSCE in emergency medicine and trauma seemed to have a relatively high level of acceptance by both staff and students. In our opinion it seems that the OSCE is a better tool for first-year level final assessment in emergency medicine and trauma. is a better tool for first-year level final assessment

Clinical Competence↗
PubMed1988

The guinea-pig isolated atrium as a model system for the central actions of selected CNS stimulant and depressant drugs. Part 2. Mechanisms involved in the actions and interactions of the convulsant bemegride and its hypnotic homologue 3-methyl-3-n-butylglutarimide.

The present study explores pharmacologically on the model spontaneously beating 3H-noradrenaline pretreated guinea-pig atrial preparation the mechanism(s) by which the representative central nervous system (CNS) stimulant drug 3-methyl-3-ethylglutarimide (bemegride, MEG) and its representative CNS depressant homologue 3-methyl-3-n-butylglutarimide (MBG) affect transmitter release and the force and rate of atrial contraction and contracture, as well as the relevance of these atrial mechanism(s) to those involved in the production of drug-evoked convulsions and hypnosis in the mammalian CNS. The process(es) involved in the interaction of MEG and MBG on the atrial preparation have also been studied to provide insight into possible CNS mechanism(s) that may be involved in the related central phenomena of drug-induced analepsis and anticonvulsant action. It would appear that the actions and interactions of MEG and MBG on the atrium and in the mouse both depend critically on glutarimide-evoked enhancement (MEG) or inhibition (MBG) of Ca2+ flux through potential-operated Ca2+ channels located primarily on the responsive atrial sarcolemmal and neuronal synaptic membranes, respectively. In addition, it seems likely that the reciprocal antagonism shown by these substances on the atrium and in the CNS is predominantly functional in nature. The pharmacological and clinical implications of these findings are discussed, with particular reference to the possible benefit of selective calcium antagonists and related drugs in the management of drug dependence and withdrawal.

Animals↗
PubMed1987

The guinea-pig isolated atrium as a model system for the central actions of selected CNS stimulant and depressant drugs. Part 1: 3,3-Diakylglutarimide homologues and related drugs.

The 3H-noradrenaline pretreated, spontaneously beating, guinea-pig atrial preparation has been used as a model system to study the presynaptic and postsynaptic actions of selected drugs with stimulant (bemegride, pentylenetetrazol, picrotoxin, strychnine and 4-methyl-4-n-propylpiperidine hydrochloride), depressant (pentobarbitone, hydroxydione, trimethadione, 3-methyl-3-n-alkylglutarimide where alkyl = butyl, amyl or hexyl, 4-methyl-4-n-propylpiperidone-2 hydrochloride, chlordiazepoxide and chlorpromazine) or dual stimulant-depressant (3-methyl-3-n-propylglutarimide and 5-ethyl-5-(1,3-dimethylbutyl) barbiturate and its (+) and (-) enantiomers) actions in the central nervous system of the mouse. 3H-Noradrenaline efflux and force and rate of atrial contraction were used as parameters of atrial function. With the exception of strychnine, picrotoxin and 4-methyl-4-n-propylpiperidine hydrochloride, which appear to act by different central mechanisms, there is good correspondence between the actions of the test drugs on the force of atrial contraction and in the CNS of the mouse. Thus, stimulant drugs increase and depressant drugs decrease the force of atrial contraction, while dual stimulant-depressant drugs in low concentrations increase, and in higher concentrations, decrease the inotropic response. A similarly good correspondence generally exists between mouse and atrium with respect to the relative stimulant and depressant potencies of the test drugs, additive stimulation or depression for pairs of like-acting drugs and 'analepsis' and 'anticonvulsant activity' for drugs with opposed central actions. No such relationships were found using tritium efflux or the chronotropic response as parameters of atrial function. Thus, the guinea-pig atrial preparation appears to be a good model system in which to demonstrate the acute CNS actions and interactions of the majority of the test drugs. Their positive and negative inotropic effects on the atrium have been explained in terms of a membrane phase distribution hypothesis of drug action, and their ability to facilitate or impede, respectively, the movement of Ca2/ across the atrial sarcolemmal membrane. It is proposed that these drugs may act by similar mechanisms at responsive sites in the brainstem reticular formation and related areas in the mouse. These may be primarily excitatory noradrenergic synapses integrated functionally with presynaptic or independent inhibitory GABAergic terminals.

Animals↗