Search PubMed⌕ Search

Biomedical subjects

A Levy

Publications and source records attributed to A Levy.

At least 307 records · Page 17Linked to original sources
PubMed1990

Relationship between somatostatin and growth hormone messenger ribonucleic acid in human pituitary adenomas: an in-situ hybridization histochemistry study.

We have used quantitative in-situ hybridization histochemistry to assess the somatostatin (SRIH) and GH messenger ribonucleic acid (mRNA) content of 81 pituitary adenomas. SRIH mRNA was found in the absence of GH mRNA in only one tumour and in the five cases in which GH and SRIH mRNA were both present, SRIH mRNA prevalence was approximately two orders of magnitude less than GH mRNA. However, no direct correlation between GH mRNA, SRIH mRNA and circulating GH levels was evident at the time of surgery. In contrast, there was no detectable SRIH mRNA probe binding to a thyrotroph adenoma, a gonadotroph adenoma, 29 endocrinologically inactive pituitary adenomas, nine lactotroph adenomas, two first trimester fetal and two normal adult pituitary glands obtained 24 and 36 h post-mortem. These findings corroborate previous reports of SRIH release from somatotroph adenomas in vitro and suggest that paracrine or autocrine mechanisms linking SRIH and GH mRNA operate within normal pituitary tissue. As somatotroph adenomas are thought to be predominantly clonal in origin, the data further suggest that GH and SRIH are synthesized in the same or closely related cells.

Adenoma↗
PubMed1990

A gonadotropin-releasing hormone (GnRH) antagonist distinguishes three populations of GnRH analog-responsive cells in human and rat pituitary in vitro and produces an acute increase in intracellular Ca2+ concentration without inducing gonadotropin secretion.

We have examined the actions of the potent GnRH antagonist [N-acetyl-D beta Na11-D-pCl-Phe2-D-Phe3-D-Arg6,Phe7,Arg8-D-Ala10]NH2GnRH++ + (GnRHa) on basal and GnRH-stimulated LH secretion, inositol phospholipid turnover, and intracellular Ca2+ levels in dispersed rat anterior pituitary tissue. As expected, GnRHa was found to be a pure antagonist of secretion, but was paradoxically equipotent with GnRH in stimulating inositol phospholipid turnover. Examination of intracellular Ca2+ changes at the single cell level using digital video-enhanced fluorescence imaging demonstrated that dispersed rat pituitary cells appeared to contain three GnRH analog-responsive cell populations: those that increased intracellular Ca2+ in response to both GnRH and GnRHa, and those that responded to either GnRH or GnRHa only. These observations were extended to studies of the relatively homogeneous gonadotroph cell populations of endocrinologically inactive pituitary adenomas. Of five adenomas examined, one increased inositol phospholipid turnover in response to GnRHa plus GnRH, but not GnRH alone, three responded to GnRH only, and one responded to both GnRH and GnRHa. Our findings, therefore, suggest that three GnRH analog-responsive cell types are also present in human pituitary and that clonal expansion of any of these cell types may be responsible for tumor formation.

Adenoma↗
PubMed1990

Competency for military arrest as a psychiatric problem.

Military law does not invest doctors with the authority to determine whether a soldier is competent to enter military arrest. This determination is legal in nature. Therefore, medical (or psychiatric) examination which is carried out before or within military arrest or detention, is aimed at preventing deterioration in the health of the soldier in prison. Hence, medical opinion serves only as 'credentials' of sorts. This is the formal language of the military law. In reality, the examining psychiatrist has to consider many factors, bearing in mind that his conclusions will probably become a prominent basis for the final decision on the military legal officer (whether to enforce military arrest). In order to illustrate the complicated considerations which are set forth before military psychiatrists, several case reports are presented of soldiers, who were examined in the Israel Defence Forces central psychiatric clinic for the determination of competency for military arrest.

Adult↗
PubMed1990

Should electroconvulsive therapy be used as an ambulatory preventive treatment?

Electroconvulsive therapy (ECT) has often been withheld from patients in many instances, even when it was the preferred form of psychiatric treatment. From clinical, social, and legal points of view, it is associated with many negative connotations. This paper reviews the use of ECT as a "legitimate" form of long-term ambulatory preventive treatment for psychiatric patients who have previously received it during hospitalization. Attempts to terminate or reduce the frequency of ECT treatments may well be the cause for readmission or exacerbation of an acute attack in patients already in remission who have been discharged.

Ambulatory Care↗
PubMed1990

Psychiatric and neuropsychological pathologies in court: an interactional approach.

Pathological functioning is often diagnosed in terms of either psychiatric dysfunction or neuropsychological deficits. There is, however, a growing belief that such an 'either or' approach is inadequate. The proposition is put forward that a 'situational diagnosis' allows for a more comprehensive assessment of behaviour and a more accurate evaluation of an offender's legal responsibility.

Adult↗
PubMed1990

Hoarding as a psychiatric symptom.

Collecting is a normal behavior in childhood and adulthood, while hoarding--the gathering, ordering, and disposal of articles without clear conscious motivation or control--is characterized as the pathologic counterpart of collecting. The literature describing the characteristics of collecting and the theories concerning its underlying mechanisms is presented along with eight case studies of adults who exhibited hoarding as a prominent symptom. It is apparent that hoarding is the final common pathway for a variety of processes: compulsive hoarding in obsessive compulsive disorder, fears of theft and poisoning in paranoid delusions, and the deterioration of habits in organic mental disorder.

Adult↗
PubMed1989

Collective motion of iron and exogenous ligands in hemoglobin.

Mössbauer studies of deoxyhemoglobin (Hb), oxyhemoglobin (HbO2), and (carbonmonoxy)-hemoglobin (HbCO) have been performed providing information regarding the center shift (CS) up to 250 K and the recoil-free fraction (f) in the "solid state regime". The temperature dependence of the CS indicates that the effective mass of the iron in liganded hemoglobin includes the exogenous ligand, suggesting that vibrations of the iron are strongly coupled to those of the ligand. As a result of this coupled motion, the recoil-free fraction (f) provides a valuable probe for the shape of the potential energy surface in the ligand pocket. Thus HbO2 experiences a stronger restoring force than HbCO, which can be attributed to a steeper potential well for the oxygen into the ligand pocket.

Carboxyhemoglobin↗
PubMed1989

Distamycin paradoxically stimulates the copying of oligo(dA).poly(dT) by DNA polymerases.

Distamycin A, a polypeptide antibiotic, binds to dA.dT-rich regions in the minor groove of B-DNA. By virtue of its nonintercalating binding, distamycin acts as a potent inhibitor of the synthesis of DNA both in vivo and in vitro. Here we report that distamycin paradoxically stimulates Escherichia coli DNA polymerase I (pol I), its large (Klenow) fragment, and bacteriophage T4 DNA polymerase to copy oligo(dA).poly(dT) in vitro. It is found that distamycin increases the maximum velocity (Vmax) of the extension of the oligo(dA) primer by pol I without affecting the Michaelis constant (Km) of the primer. Gel electrophoresis of the extended primer indicates that the antibiotic specifically increases the rate of addition of the first three dAMP residues. Lastly, in the presence of both distamycin and the oligo(dT)-binding protein factor D, which increases the processivity of pol I, a synergistic stimulation of polymerization is attained. Taken together, these results suggest that distamycin stimulates synthesis by increasing the rate of initiation of oligo(dA) extension. The stimulatory effect of distamycin is inversely related to the stability of the primer-template complex. Thus, maximum stimulation is exerted at elevated temperatures and with shorter oligo(dA) primers. That distamycin increases the thermal stability of [32P](dA)9.poly(dT) is directly demonstrated by electrophoretic separation of the hybrid from dissociated [32P](dA)9 primer. It is proposed that by binding to the short primer-template duplex, distamycin stabilizes the oligo(dA).poly(dT) complex and, therefore, increases the rate of productive initiations of synthesis at the primer terminus.

Adenosine Monophosphate↗
PubMed1989

(+-)-cis-2-methyl-spiro(1,3-oxathiolane-5,3') quinuclidine (AF102B): a new M1 agonist attenuates cognitive dysfunctions in AF64A-treated rats.

(+-)-cis-2-Methyl-spiro(1,3-oxathiolane-5,3')quinuclidine (AF102B), a new muscarinic agonist of utmost rigidity, exhibits a high selectivity for M1 muscarinic receptors. In rats having a cholinergic hypofunction induced by the intracerebroventricular administration of ethylcholine aziridinium (AF64A), AF102B reversed cognitive impairments in a step-through passive avoidance task and in an 8-arm radial maze. AF102B reversed cognitive impairments at significantly lower doses than those needed to induce side-effects. In addition, AF102B exhibited low toxicity. The results suggest that AF102B may prove useful for treatments of cholinergic deficiencies and cognitive impairments, like those reported in Alzheimer's disease.

Alzheimer Disease↗
PubMed1989

Mössbauer, EPR and NMR studies of the acid-induced reduction and changes in spin state of ferric bleomycin.

Iron-57 Mössbauer, electron paramagnetic resonance (EPR) and H-1 nuclear magnetic resonance (NMR) studies of iron-bleomycin complexes in the pH range from 1.0 to 6.0 are reported. Sequential protonation of the ligands produces a variety of high-spin and low-spin complexes of the metal. Of particular interest is the reversible equilibrium between Fe(III)- and oxygen-stable Fe(II)-bleomycin. Below pH 3.5 Fe(II) complexes form, with maximal reduction occurring at approximately pH 2. At still lower pH, Fe(III) complexes unassociated with bleomycin become dominant. The observed reduction in the absence of exogenous reducing agents suggests the possible involvement of intramolecular autoreduction in bleomycin-mediated DNA degradation.

Bleomycin↗
PubMed1989

[Competency for military arrest as a psychiatric problem].

Military law does not invest physicians with the authority to determine whether a soldier is competent when faced with military arrest, as this is a legal determination. Therefore, medical (or psychiatric) examination carried out before or during military arrest or detention, is aimed at preventing deterioration in the health of the imprisoned soldier. Hence, medical opinion serves only as a "credential" of sorts, the formal language of the military law. In reality, the examining psychiatrist has to consider many factors, including the probability that his conclusions will provide an important basis for the decision of the military legal officer as to whether to enforce military arrest. To illustrate the complicated considerations facing military psychiatrists, several case reports are presented of patients examined in the Israel Defence Forces central psychiatric clinic as to competency for military arrest.

Forensic Psychiatry↗
PubMed1989

Kluver-Bucy syndrome in systemic lupus erythematosus.

The Kluver-Bucy syndrome has not been previously reported as a complication of systemic lupus erythematosus (SLE). A 48-year-old female is described who sustained several cerebral infarcts, some of which were bitemporal, due to SLE vasculopathy. She developed a complex behavioural picture consisting of global aphasia, left-side neglect, hyperorality, hypermetamorphosis and hypersexuality. She displayed appropriate emotional reaction to visually presented objects, indicating that her Kluver-Bucy syndrome could not be explained by lack of visual recognition.

Aphasia↗