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Biomedical subjects

S Levy

Publications and source records attributed to S Levy.

At least 199 records · Page 11Linked to original sources
PubMed1988

The localization of calcium release by inositol trisphosphate in Limulus photoreceptors and its control by negative feedback.

Microvillar photoreceptors of invertebrates exhibit a light-induced rise in the intracellular concentration of free calcium (Cai) that results in part from release of calcium from an intracellular compartment. This light-induced release of calcium appears to result from a cascade of reactions that involve rhodopsin, a GTP-binding protein and a phospholipase-C which releases inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) from the plasma membrane; the Ins(1,4,5)P3 acts to release calcium from smooth endoplasmic reticulum. In the ventral photoreceptor of the horseshoe crab Limulus polyphemus not all of the endoplasmic reticulum is subject to calcium release by Ins(1,4,5)P3. Only endoplasmic reticulum in the light-sensitive region of the cell is competent to release calcium in response to Ins(1,4,5)P3. The release of calcium by Ins(1,4,5)P3 in ventral photoreceptors appears to be subject to feedback inhibition through elevated Cai. We suggest that this feedback inhibition contributes to sensory adaptation in the photoreceptor and may account for oscillatory membrane responses sometimes observed with large injections of Ins(1,4,5)P3.

Animals↗
PubMed1988

A comparison of obstetrical records of autistic and nonautistic referrals for psychoeducational evaluations.

Heretofore most studies dealing with the association between perinatal complications and autism have used a normal comparison group. In this study obstetrical records of 59 autistic children were compared to those of 28 nonautistic children whose intelligence has a similar range and distribution as the autistic sample. Using an optimality score to reflect number of obstetrical complications, we found that the nonautistic controls experienced less optimal conditions than the autistic sample. Abnormal presentation at birth is the only factor that occurred more frequently for the autistic sample than control sample.

Adolescent↗
PubMed1988

Hybridoma fusion cell lines contain an aberrant kappa transcript.

The V region sequence of a non-productive kappa transcript from two myeloma fusion partners has been determined. This transcript has an aberrant VJ recombination site resulting in a translation stop site at position 105. It is variably expressed in hybridomas made from all fusion partners derived from the original MOPC-21 tumor. The amount of this transcript may greatly exceed levels of the productive light chain mRNA.

Animals↗
PubMed1988

High energy transcatheter cardioversion of chronic atrial fibrillation.

A new technique of internal transcatheter cardioversion of chronic atrial fibrillation using high energy shocks (200 to 300 joules) was performed in 10 patients. In all patients, external cardioversion (300 to 400 joules) and pharmacologic therapy failed to restore sinus rhythm. Atrial fibrillation was poorly tolerated despite digitalis therapy alone (five patients) or in combination with amiodarone (five patients). High energy transcatheter cardioversion was performed by pulling back the atrioventricular (AV) junction catheter just inferior to the site of His bundle recording and delivering the shock between a proximal electrode (catheter) and backplate (anode). High energy internal cardioversion restored sinus rhythm in 9 of the 10 patients. However, atrial fibrillation recurred within 3 min in two of them; in the remaining patient, the procedure failed to terminate atrial fibrillation. The only complication observed was transient (3 to 315 s) heart block immediately after shock delivery and this was treated by temporary pacing. Seven patients had sinus rhythm on discharge from the hospital, but in three, recurrent atrial fibrillation appeared at 8 days and 2 and 4 months, respectively. A second attempt of transcatheter cardioversion was performed in two patients and was successful in one patient. With a follow-up ranging from 2 to 11 months, five patients continued to have sinus rhythm. These preliminary results suggest that high energy internal cardioversion may be an alternative to AV junction ablation in selected patients with poorly tolerated chronic atrial fibrillation in whom external cardioversion was unsuccessful.

Adult↗
PubMed1988

Phylogeny of metabolic pathways: O-acetylserine sulphydrylase A is homologous to the tryptophan synthase beta subunit.

The cysK gene of Escherichia coli K-12 encoding O-acetylserine sulphydrylase A, was cloned and its nucleotide sequence, together with that of the flanking regions, was determined. The deduced amino acid sequence of the carboxy-terminal moiety of O-acetylserine sulphydrylase A shows significant similarity to the amino acid sequence of tryptophan synthase beta chain from several organisms. This sequence similarity is likely to reflect the structural homologies of substrates shared by both enzymes. This may indicate that these proteins, although catalysing different reactions in different metabolic pathways, have evolved from a common ancestral gene.

Amino Acid Sequence↗
PubMed1988

Long-term follow-up of patients treated with VVI pacing and sequential pacing with special reference to VA retrograde conduction.

The aim of this prospective study is comparing long-term prognosis in patients implanted with a VVI pacemaker (group A) with those implanted with a sequential pacing device, AAI or DDD, (group B). Both groups of 45 patients each, were comparable as regards to age, sex, pacing indications, underlying heart disease, and technical conditions of implantation and were followed-up over 55 months. Atrial arrhythmias (A.A.) incidence was higher in group A: 24.4% than group B: 8.8% (P less than 0.05). Arterial embolisms (A.E.) occurred in group A patients only. Worsening or occurrence of exercise limitation was more frequent in group A: 35.6% as compared to group B: 13.3% (P less than 0.05) and deaths related to these complications, occurred in seven cases in group A versus four cases in group B. In group A, all patients who experienced a worsening or occurrence of an A.A. or an A.E., had a ventriculoatrial conduction (VAC). No statistical difference was observed in worsening or occurrence of exercise limitation between patients with VAC and those without VAC: nine (42.8%) and seven (29.2%) but they respectively experienced at least one complication in 16 cases (76.2%) and seven cases (29.2%) (P less than 0.01). In conclusion, long-term prognosis in patients implanted with VVI pacing as compared to patients implanted with sequential pacing is poorer. The presence of VAC in patients treated with permanent VVI pacing is a major factor for complications and deaths related to A.E. and cardiac failure. Thus VVI pacing should be avoided in patients with VAC.

Arrhythmias, Cardiac↗
PubMed1988

[Cardiomuscular lysosomal glycogenosis in adults without known enzyme deficiency. A cause of familial myocardiopathy and lysosomal glycogen overload with normal acid maltase].

An unusual form of familial myocardiopathy is reported. The disease affected siblings entering adulthood and presented as subclinical skeletal muscle and patent cardiac muscle lesions. Quadriceps muscle biopsy performed in a young man who subsequently died of cardial failure revealed excessive lysosomal glycogen storage, as in type II glycogenosis, but biochemistry showed normal enzymatic activity. In a sister with hypertrophic myocardiopathy only leucocytes were examined; they also showed normal enzymatic activity. Other clinical manifestations of this form of familial myocardiopathy are hypoglycaemia and moderate skeletal muscle involvement. At histology, the image is that of Pompe's disease, but the acid maltase level is normal. The condition seems to be transmitted as an autosomal dominant trait.

Adult↗
PubMed1988

[Treatment using lymphocytapheresis of severe forms of Crohn's disease. Preliminary results].

We report our experience in the treatment of severe Crohn's disease by lymphocytapheresis (LCTPH). Twelve patients with severe Crohn's disease unresponsive to prednisone for two years were treated by twelve sessions of LCTPH over a three-week period. Approximately 4.5 x 10(9) lymphocytes were removed at the end of each session, total lymphocyte removal per patient ranging from 1.9 to 10.7 x 10(8)/kg. Sessions were well tolerated. Clinical improvement was observed in all patients at the end of their LCTPH courses. However only fifty per cent of these patients achieved clinical remission of three months and for two of them the remission lasted 8 and 9 months. We examined the immediate effects of cytapheresis on peripheral blood lymphocytes and monocytes. No correlation was noted between the clinical efficacy of LCTPH and the quantity of lymphocytes (T3, T4, T8, NK) and/or monocytes removed. The only significant change was a partial recovery of NK activity in the good responders. The optimal modalities of depletion and the advantages of this treatment in severe Crohn's disease have to be defined in multicentric controlled studies.

Adult↗
PubMed1988

Respiratory muscle rest therapy.

This article discusses the role of respiratory muscle rest therapy in hypercapnic ventilatory failure and/or inspiratory muscle fatigue associated with primary lung disease, diseases of the chest wall, and neuromuscular diseases. Some animal data on the role of ventilatory muscle rest therapy in states characterized by a low cardiac output and arterial hypotension are also reviewed. Additionally, a method for quantitating the degree of respiratory muscle rest elicited by negative pressure ventilation devices is presented.

Cardiac Output, Low↗
PubMed1987

Idiotype vaccination against murine B cell lymphoma. Humoral and cellular responses elicited by tumor-derived immunoglobulin M and its molecular subunits.

C3H/HeN mice were immunized with idiotypic immunoglobulin M (IgM) and its molecular subunits from the syngeneic 38C13 lymphoma. Immunization with idiotypic IgM (38C-Id) resulted in idiotype-specific humoral and cellular immunity and protection against a lethal tumor cell challenge. Heavy (H38C) and light (L38C) chains were isolated by electroelution from preparative polyacrylamide gels. Both of these immunogens induced significant resistance to a subsequent tumor challenge. Variable region immunogens, in the form of trpE-fusion proteins, were obtained by cloning heavy and light chain variable region genes into the expression plasmid pATH-11. Of these, only the trpE-VH38C immunogen yielded immune resistance to tumor challenge. Finally, the nucleic acid sequence of 38C-Id light chain was determined and, based on the corresponding amino acid sequence and an analysis of predicted secondary structure, a region of potential antigenicity in complementarity-determining region 3 was chosen for the production of a synthetic peptide. Vaccination with this synthetic peptide resulted in significant suppression of tumor growth. Analysis of the humoral and cellular immunity generated by these vaccines revealed the presence of antibodies reactive with native idiotypic IgM only in 38C-Id, H38C, and trpE-VH38C immune sera, although the latter two were not idiotype-specific. Idiotype-specific lymphocytes, which proliferated in response to native 38C-Id, were observed in all immune animals. With the exception of the fusion protein immunogens, conjugation to an immunogenic carrier protein (keyhole limpet hemocyanin or thyroglobulin) was required for optimal humoral and cellular responses.

Amino Acid Sequence↗