Search PubMed⌕ Search

Biomedical subjects

S Levy

Publications and source records attributed to S Levy.

At least 181 records · Page 10Linked to original sources
PubMed1990

[Wolff-Parkinson-White syndrome. Value of intravenous flecainide for detecting Kent's pathways with short refractory period].

The aim of this study was to assess the value of a non-invasive test in detecting accessory pathways with short anterograde effective refractory periods (AERP) (less than or equal to 270 ms) in patients with the Wolff-Parkinson-White syndrome. An intravenous injection of Flecainide acetate was administered to 19 consecutive patients referred for electrophysiological investigation of a WPW syndrome with permanent pre-excitation of the surface electrocardiogram. The first 8 patients (Group I) received a dose of 1.5 mg/kg over 5 minutes and the following 11 patients (Group II) were given 2 mg/kg in 5 minutes. In Group I, preexcitation disappeared in 3 patients (37.5%) who all had accessory pathways with AERP greater than 270 ms. It persisted in the other 5 patients (62.5%) of whom 4 had AERP less than or equal to 270 ms and 1 an AERP greater than 270 ms (false negative). In Group II, preexcitation disappeared in 8 patients (72.2%) of whom 4 had AERP greater than 270 ms and 4 had AERP less than 270 ms (false positives). Preexcitation persisted in the 3 other patients (27.3%); the AERP was less than or equal to 270 ms in 2 patients and greater than 270 ms in the other patients. These results suggest that intravenous Flecainide acetate at the dose of 1.5 mg/kg could be useful in differentiating WPW syndromes with long refractory periods (greater than 270 ms) from those with short refractory periods (less than or equal to 270 ms) with a satisfactory sensitivity and specificity, and that further studies on larger numbers of patients are required to confirm this hypothesis.

Adolescent↗
PubMed1990

Negative-pressure ventilation.

In this review, we make the following major points: (1) Canine experiments indicate that in an experimental model of ARDS, cyclic NPV plus NEEP is as effective as cyclic PPV plus PEEP in treating arterial hypoxemia. Because cyclic NPV plus NEEP does not depress cardiac output as much as cyclic PPV plus PEEP, further study of this potential therapy is warranted. (2) At the present time, NPV has little use in neonatal medicine. (3) However, in adult medicine, NPV is efficacious for providing chronic ventilatory support in patients with neuromuscular and chest wall diseases. Additionally, the role of NPV in postoperative weaning warrants further study. (4) Some data in the literature suggest that some subsets of patients with CAL may benefit from chronic intermittent NPV therapy. However, criteria for identifying these patients have not been established. (5) Some investigators have recently demonstrated that PPV delivered via the nares can elicit VMR. Because this technique provides us with the opportunity to elicit VMR by a method other than NPV, nasal PPV provides us with a method to directly validate our presumption that improvements in COPD patients are related to VMR per se.

Adult↗
PubMed1989

Functional immunoglobulin light chain genes are replaced by ongoing rearrangements of germline V kappa genes to downstream J kappa segment in a murine B cell line.

A murine B cell lymphoma (38C13) was subjected to immunoselection with mAbs directed against the idiotypic determinants of its cell surface Ig. Variants emerged with altered Ig receptors containing identical heavy chains but different light chains. The functional light chain genes in these variants were composed of V kappa segments drawn from the V kappa Ox-1 family, which had replaced the V kappa gene expressed by the parental tumor by rearranging to downstream J kappa segments. Rearrangement at the kappa locus continued to occur spontaneously, giving rise to secondary and tertiary variants at a rate of 1.9 x 10(-4) per cell per generation. Variants were isolated that had ceased production of surface Ig but went on to rearrange again and to become surface Ig+. The Ig- state may be an intermediate step providing a stimulus for continued rearrangement. This process provides an additional mechanism for generating diversity within B cell clones and expands the use of the available repertoire of Ig genes.

Animals↗
PubMed1989

Activation of an excluded immunoglobulin allele in a human B lymphoma cell line.

Mature B cells that express surface immunoglobulin (Ig) are usually committed to their original Ig product. It was shown that such a cell can replace its light chain by rearranging and expressing a new light chain from the other allele. Anti-idiotype antibodies were used to isolate idiotypic variants from a surface IgM+lambda+ human B cell tumor line. The variants expressed a new lambda light chain. Both the original and the new lambda transcripts were present in the variant cells, but only the new one was expressed as a protein on the cell surface. Therefore, although the cell exhibited allelic exclusion and had only one Ig receptor at a time, the commitment to a particular light chain gene was reversible.

Alleles↗
PubMed1989

Countertransference and failure to report child abuse and neglect.

Though every state has laws requiring the report of suspected child abuse and neglect, failure to report remains a significant problem. Review of previous research on failure to report suggests that the reporters' anxieties about disrupting their relationship with the child's family as well as the reporters' gender, experience, and training affect willingness to report. Countertransference fear, guilt, shame, and sympathy are discussed as a basis for understanding the reporter's anxieties. We suggest that countertransference issues should be addressed in the training and ongoing practice of mandated reporters. The following mechanisms are offered to deal with this issue in training and practice: (1) teaching professionals about how countertransference reactions may arise during the reporting process (this training may include the use of risk management groups for private practitioners); (2) identification of a community child abuse expert for consultation; and (3) educating child protection workers about psychodynamics aspects of case management.

Anger↗
PubMed1989

Societies in transition: mortality patterns in Pacific Island populations.

The 22 Pacific Island countries and territories are in a state of demographic and epidemiological transition. Mortality data for the period around 1980 were collected from various sources and are presented in this comparative study. Because death registration in many Pacific countries is deficient some data have been adjusted for underenumeration; and some mortality estimates have been calculated by indirect means, using data from censuses or surveys. Cause of death information is affected by diagnostic inaccuracy and often tabulated in broad categories only; in some Pacific countries cause of death data are only available on hospital deaths. The less developed Melanesian malarious countries and the less developed dispersed atoll nations manifest higher mortality, and higher proportional mortality from infectious disease compared with other states. The more developed US-associated states, two New Zealand-associated states, and New Caledonian Europeans all have reasonably low mortality, and relatively high proportional mortality from cardiovascular disease (CVD). Females have longer life expectancy at birth than males in all countries except Vanuatu and the Solomon Islands. The phosphate-rich island of Nauru presents an atypical picture with considerable adult male mortality from diseases associated with modernization.

Adolescent↗
PubMed1989

The importance of pelvic tilt in reducing compressive stress in the spine during flexion-extension exercises.

An explanation for the importance of pelvic tilt exercises is proposed. This explanation derives from a mathematical model that predicts the existence of a relationship between lordosis (pelvic tilt) and the distribution of stresses within the spine. The model predicts that, for every angle of forward flexion, there is a unique degree of lordosis that will minimize and equalize the compressive stress within the spine. This stress-minimizing posture also is associated with the minimum muscular activity; the balance of the moment is supported by passive stretching of the connective tissues. These predictions were tested by comparing them with empirical values of spinal geometry and muscular activity, as measured simultaneously by an opto-electronic motion analysis and electromyographic (EMG) data collection system.

Exercise↗
PubMed1989

Hepatitis B infection in Vanuatu: age of acquisition of infection and possible routes of transmission.

Seroepidemiological studies of hepatitis B were carried out on diverse groups of children (477) and adults (629) from the Pacific Island country of Vanuatu. In children under 14 years, prevalences of HBsAg and of all markers were 6% and 53.3% respectively; in adults greater than or equal to 20 years the prevalences were 15% and 70%. Age specific prevalence of hepatitis B infection (all markers) was low in infancy (less than 1 year) but rose sharply afterwards, suggesting that the main mechanism of transmission was horizontal spread. This finding is consistent with other developing country studies from the Pacific Islands and elsewhere. In view of the main ages and mechanisms of transmission of hepatitis B in children in developing countries and the need for simple and inexpensive immunisation strategies in this context, it is recommended that mass vaccination of all infants with hepatitis B vaccine be undertaken in hyperendemic areas.

Adolescent↗
PubMed1989

Hemorrhagic tonsillitis.

Eleven patients with acute and/or chronic tonsillitis, who presented with a spontaneous tonsillar hemorrhage are reported and discussed. Two patterns of hemorrhage were noted: 1. diffuse, parenchymal bleeding and 2. localized bleeding from dilated surface vessels. Pharyngeal culture for group A beta-hemolytic Streptococcus was positive in six patients (55%). Monospot, heterophile antibodies, complete blood cell count, prothombin time, partial thromboplastin time, and viral studies did not consistently demonstrate any abnormality. Two patients, however, did have an elevation in liver enzymes. In five patients, the bleeding stopped spontaneously; in five patients the bleeding was controlled with local chemical cautery. In two patients, Avitene was used for hemostasis. One other patient's bleeding was controlled by electrocautery while the patient was under anesthesia for endoscopic evaluation of hemoptysis. Two patients required blood transfusions; one of these patients had a history of factor IX deficiency. Four case histories are discussed in detail to illustrate the varied clinical presentation and some pitfalls in diagnosing and managing this rarely reported complication of tonsillitis. Possible mechanisms for the pathophysiology include increased tonsillar blood flow, necrosis of tonsillar surface cells, and trauma to dilated surface vessels. No common bacterial or viral etiology could be determined in this rare, but potentially serious, complication of tonsillitis.

Acute Disease↗
PubMed1989

[Arrhythmogenic effects of antidepressive agents demonstrated by programmed ventricular pacing].

Tricyclic antidepressants and phenothiazines have been blamed for increasing the incidence of sudden death. One of their known mechanisms of action in such cases is to induce torsades de pointes by a so-called "quinidine-like" effect. We report the case of a female patient who was rescued from an episode of cardiac arrest which occurred two months after a myocardial infarction. Right ventricular programmed pacing strongly suggested an arrhythmogenic effect to the antidepressant the patient was receiving. This type of treatment seems to be capable of facilitating the induction of a monomorphous ventricular tachycardia which may degenerate into ventricular fibrillation.

Antidepressive Agents, Tricyclic↗
PubMed1989

[Atrioventricular block, a complication of radiotherapy of the mediastinum].

Cardiac complications of mediastinal irradiation usually concern the pericardium, the ventricular myocardium and the coronary arteries. We report the case of a 42-year old woman who experienced a syncopal atrioventricular (AV) block 12 years after irradiation of a mediastinal Hodgkin's lymphoma. Electrophysiological recordings showed infranodal conduction disturbances. A review of the literature yielded only 12 cases of syncopal radiation-induced AV block. This case highlights the risk of syncopal AV blocks occurring a long time after mediastinal irradiation and leading to severe damage of the His bundle and its branches. The presence, as in our patient, of an associated right ventricular outflow tract stenosis confirms the importance and severity of radiation-induced cardiac lesions.

Adult↗
PubMed1989

[Urokinase recanalization of extensive thrombosis of the superior vena cava secondary to an implantable perfusion device].

A superior vena cava syndrome developed suddenly in a 36 year old man who had been undergoing chemotherapy via an implanted venous access catheter for 18 months. Venography showed superior vena cava thrombosis extending bilaterally to the subclavian veins. Direct local thrombolysis with low-dose Urokinase resulted in partial recanalisation with an excellent clinical result despite the persistence of an endovenous sequestrum situated at the catheter tip, a sequela of previous thrombosis. This case underlines the importance of direct local thrombolysis in patients with a Port-a-Cath system complicated by a thrombosis.

Adult↗
PubMed1989

Elevated serum levels of soluble interleukin-2 receptors in HIV infection: no correlation with activated T cells.

Serum levels of soluble interleukin-2 receptors (sIL-2R) were measured in 105 HIV-seropositive individuals simultaneously with T cell subsets and activated T cells (CD3+ and HLA-DR+). Significantly elevated levels of serum sIL-2R were found (564 +/- 259 U/ml versus 258 +/- 87 U/ml in 70 controls, p less than 0.001), as well as increased numbers of activated T cells (mean numbers, 579/microliters in the patients versus 113/microliters in 26 controls, p less than 0.0001). Correlation analysis did not disclose any significant association between elevated sIL-2R and increased activated T cells, nor with decreased CD4+ lymphocytes. These data suggest that sIL-2R in HIV infection do not emanate from activated T cells and are not linked to CD4+ cell loss.

Adolescent↗
PubMed1988

Effects of Na+ and Ca2+ gradients on intracellular free Ca2+ in voltage-clamped Aplysia neurons.

Selected neurons of the abdominal ganglion of Aplysia californica were voltage-clamped and intracellular free Ca [( Ca2+]i) and Na [( Na+]i) concentrations were monitored with ion selective microelectrodes. Reducing [Na+]o from 500 mM (normal seawater, NSW) to 5 mM resulted in a decrease of the potential measured by the Ca electrode (VCa). Increasing [Ca2+]o from 10 to 50 mM increased [Ca2+]i two-fold, keeping [Ca2+]o at 50 mM and decreasing [Na+]o to 5 mM still led to a decrease in VCa. With 100 mM [Ca2+]o, which also increased [Ca2+]i, decreasing [Na+]o increased VCa in two of the eight cells tested. This indicates that in normal or moderately high resting [Ca2+]i, Ca2+ extrusion by Na/Ca exchange (forward mode) is not essential for [Ca2+]i buffering. [Na+]i was 12.9 +/- 3.6 mM (S.E.M., n = 7) in NSW; reducing [Na+]o to 5 mM decreased [Na+]i to 2.0 +/- 1.1 mM (S.E.M.). Keeping [Na+]o at 5 mM and increasing [Ca2+]o from 10 to 20 mM further decreased [Na+]i to about 1.0 mM, evidence of Na/Ca exchange operating in the reverse mode. Attempts to increase [Ca2+]i by bath application of the Ca ionophores A23187, X537A, ionomycin or ETH 1001 resulted in no measurable change of the resting [Ca2+]i. Application of Ouabain caused an apparent increase in [Ca2+]i in two of the six cells tested. In cells injected with the metallochromic indicator arsenazo III (AIII), the rate of the falling phase of the AIII absorbance increase, following a voltage-clamp pulse, was significantly slower in 5 mM [Na+]o. This indicates that in its forward mode Na-Ca exchange is active in clearing large submembrane increases in [Ca2+]i.

Animals↗
PubMed1988

Alternative V kappa gene rearrangements in a murine B cell lymphoma. An explantation for idiotypic heterogeneity.

Idiotype variants of 38C13, a murine B cell lymphoma, have been isolated by immunoselection with antiidiotype mAbs. The V region genes for the kappa light chains and mu heavy chains expressed by these tumor cells were sequenced and compared. There was no evidence for V region somatic point mutation in this tumor. However, while the heavy chain genes were all identical, the light chain genes were all different. The light chain genes of each variant were derived from the V kappa-Ox1 gene family and joined to J kappa 4, whereas the light chain gene of the parental tumor was derived from the V kappa 9 family and joined to J kappa 2. Two of the variants used the identical V kappa gene but differed by the inclusion of a variable number of additional nucleotides in the V/J joint. Thus, the idiotypic heterogeneity of this B cell lymphoma arises as a consequence of alternative light chain rearrangements rather than point mutation. This process repetitively uses members of the same V kappa gene family. Two of the variants use the identical V kappa and J kappa gene segments but differ by the presence of extra nucleotides at the V kappa/J kappa joint.

Amino Acid Sequence↗
PubMed1988

Mutational hot spots in Ig V region genes of human follicular lymphomas.

The genes coding for the Ig light chains expressed in two cases of human follicular lymphoma were cloned and sequenced. In each case, multiple independent isolates of the tumor population were compared. Although each tumor represented a single clone of B cells with a unique V/J joint, different cells within each tumor had accumulated multiple point mutations in the V gene during clonal expansion. Most of the mutations observed were silent, but some resulted in amino acid replacements. Identical silent mutations were often observed in independent isolates of each tumor. By combining the current data with VH sequences obtained previously from the same cells, it was apparent that the repetitive silent mutations could not be explained solely by a genealogic tree. Such mutations could represent hot spots whose tendency to mutate may be influenced by neighboring DNA sequences or by the methylation of specific cytosine residues.

Amino Acid Sequence↗