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Biomedical subjects

L Siegel

Publications and source records attributed to L Siegel.

At least 19 recordsLinked to original sources
PubMed1989

The effect of lead on thyroid function in children.

Exposure to inorganic lead has been associated with impaired uptake of iodine by the thyroid as well as depressed estimated free thyroxine levels in occupationally exposed adults. Consideration of the serious consequences of impaired thyroid function in young children prompted investigation of the effects of lead on thyroid function in children. Blood lead determinations and thyroid function tests were performed on 68 children examined at a hospital outpatient pediatric clinic. Serum thyroxine (T4) and free thyroxine (FT4) levels were within the normal range for all patients. No statistically significant relationship was found between lead levels and T4 or FT4 levels. We conclude that lead is unlikely to have a clinically significant effect on thyroid function in children exposed in inner cities at prevailing levels.

Child↗
PubMed1988

The effects of methylphenidate on levels of processing and laterality in children with attention deficit disorder.

Effects of stimulant medication (methylphenidate) on levels (feature, name, semantic) of word processing by the left and right hemisphere were assessed in 31 attention-deficit-disordered children. In a double-blind procedure, same-different decisions were made to tachistoscopically presented word pairs under medication and placebo. Analysis of manual response times failed to show any negative effects of medication. Feature decisions were faster than name decisions, which were faster than semantic decisions. Methylphenidate induced a right visual field advantage (left hemisphere) for the name decision, which was interpreted as a normalization effect. The results suggest that (1) methylphenidate may selectively improve the phonological level of word processing and (2) methylphenidate's favorable therapeutic effect is produced through inhibition of excessive right hemisphere activity in response to task demands that engage the left hemisphere.

Adolescent↗
PubMed1988

Anesthetic mishaps and the cost of monitoring: a proposed standard for monitoring equipment.

Review of insurance data indicates that approximately 1.5 claims are paid per 10,000 anesthetic procedures, a conservative estimate of the incidence of preventable serious injury associated with anesthesia. Insurance data permit estimation of the premium cost for the anesthesiologist and hospital, per operating room per year, of $69,429.00. We propose the use of an enhanced monitoring standard requiring a pulse oximeter, capnograph, spirometer, halometer, automatic sphygmomanometer, breathing circuit oxygen analyzer, stethoscope, electrocardiographic monitor, and temperature monitor. We suggest that this premium cost, together with the estimate that 50% of incidents would be avoided, predicts a resultant saving of over $27,000/operating room/year, a savings equal to the entire cost of the enhanced monitoring system in approximately 8 months, or a yearly savings of over five times the annualized expense of the monitoring system. Thus, in addition to the moral imperative to monitor a patient during anesthesia to avoid injury and death, there is an economic incentive to monitor effectively.

Anesthesia↗
PubMed1987

Latency of mouse cytomegalovirus in sciatic nerve.

This report describes a mammalian model for exploring the role of virus in peripheral neuropathy. Schwann cells in culture were permissive for mouse cytomegalovirus (MCMV) replication. Intraperitoneal inoculation rarely led to sciatic nerve infection. Sciatic nerves infected by direct intraneural injection produced infectious virus and contained viral antigen at 4 days postinfection (pi). Nerves taken later, at 4 to 8 weeks pi, contained no infectious virus, but MCMV was present in a latent state because culture of nerve explants reactivated virus. The findings contrast the viral permissiveness of cultured Schwann cells to the latency observed in intact peripheral nerve.

Animals↗
PubMed1986

Theiler's virus in brain cell cultures: lysis of neurons and oligodendrocytes and persistence in astrocytes and macrophages.

The mechanisms of persistence and of demyelination in Theiler's virus (TV)-induced chronic neurologic disease (a murine model for multiple sclerosis) are, as yet, disputed. We investigated the tropism and persistence of TV in brain cell culture to better understand the pathogenesis of this disease. Using anti-genic markers to identify specific cells in culture, we have demonstrated that TV infects, lytically, neurons and oligodendrocytes and persistently astrocytes and macrophages. These results suggest that host cell factors play a key role in the mechanism of demyelination and the persistence of TV in the nervous system.

Animals↗
PubMed1986

AIDS: relationship to alcohol and other drugs.

Most people who are exposed to AIDS do not get the syndrome. It seems clear that there must be cofactors. Most people with AIDS have a history of alcohol or other drug use, and many of the drugs used have been shown to suppress the immune system. The correlation between drug use and development of AIDS in several populations is striking, and it is suggested that definitive research into this possible cofactor be urgently initiated. The elimination of cofactors may present an immediate way to control this epidemic. Suggestions are made as to how and why alcohol and drug treatment professionals should become a part of this effort.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Therapy for late post infarction ventricular tachycardia.

Non-sustained ventricular tachycardia (VT) in the late post myocardial infarction (MI) period (7-21 days) has been reported to be a predictor of sudden death. We suspected that patients with 3 beat VT on Holter monitoring in the late infarction period would demonstrate electrical instability at electrophysiologic studies. Forty-seven patients were identified as having at least 3 beat VT on Holter monitoring. Eighteen patients refused electrophysiologic studies or were not referred by their attending physician. The mean ejection fraction of this group was 43 +/- 16%. Eight patients have died, 3 sudden deaths in 13 +/- 5 months, a 17% incidence of sudden death. Twenty-nine patients underwent invasive electrophysiologic studies. Their mean ejection fraction was 37 +/- 7%, and 28 had inducible, 18 sustained ventricular tachycardia and 10 non-sustained VT. No complications were noted with electrophysiological testing in the post infarction patients. Using programmed electrical stimulation studies an effective antiarrhythmic agent preventing VT induction (usually experimental) could be found for each patient. After a mean follow-up of 12.5 +/- 4 months, the patient without inducible VT is alive and 26 of the 28 "inducible" patients are alive and well. Two patients died, one of stroke and one due to pump failure following a second MI. No sudden deaths were observed in this group. Two patients had breakthrough arrhythmias and were treated by alternative antiarrhythmic therapy that was also effective at the initial electrophysiologic studies. Thus, PES studies post MI are safe and may be an effective way to assess therapy for patients in the early post MI period, identified at high risk for sudden death.

Aged↗
PubMed1984

Total hydrolyzable glycerol in amniotic fluid, and its relationship to fetal lung maturity.

We describe an enzymic quantification of total hydrolyzable glycerol in amniotic fluid. An extract of amniotic fluid is hydrolyzed in mild alkali, without pretreatment with lipase. The resulting glycerol (some of which may be derived from trace amounts of triglyceride) is then enzymatically phosphorylated with adenosine 5'-[gamma 32P]triphosphate to yield glycerol [gamma 32P]phosphate. After removal of excess [gamma 32P]ATP by charcoal, the radioactivity of the glycerophosphate is measured in a liquid scintillation counter. The close correlation (r = 0.96) we found between total hydrolyzable glycerol and phosphatidylglycerol indicates that the contribution of triglyceride to the value for total glycerol is inconsequential. This method is less time consuming and more precise than the method for phosphatidylglycerol.

Amniotic Fluid↗
PubMed1983

An enzymic radiochemical method for determining phosphatidylglycerol in amniotic fluid.

We describe an enzymic quantification of phosphatidylglycerol in amniotic fluid. Phosphatidylglycerol is hydrolyzed in alkali and the resulting glycerol is then enzymatically phosphorylated with adenosine 5'-[gamma-32P]triphosphate to yield glycero[32P]phosphate. After removal of excess [gamma-32P]ATP by charcoal, the radioactivity of the glycerophosphate is measured in a liquid scintillation counter. Triglyceride in the amniotic fluid is hydrolyzed by lipase before extraction and thus does not interfere with the analysis. This method is specific for phosphatidylglycerol. Preliminary studies suggest that a phosphatidylglycerol value greater than or equal to 10 nmol/mL correlates with fetal lung maturity.

Amniotic Fluid↗
PubMed1981

New method for determining lecithin and sphingomyelin in amniotic fluid.

We describe a new method of complete analysis for lecithin, lysolecithin, and sphingomyelin in amniotic fluid. The analysis is based on alkaline hydrolysis of the lecithins and the enzymic hydrolysis of sphingomyelin. The choline formed in each instance is enzymically phosphorylated with [gamma-32P]ATP to yield [gamma-32P]phosphorylcholine, which is isolated by anion-exchange chromatography and shown to be stoichiometrically related to lecithin, lysolecithin, and sphingomyelin. Other phospholipids do not interfere. Using this methodology, we developed three potential approaches to the assessment of fetal lung maturity: the ratio of lecithin plus lysolecithin (total lecithin) to sphingomyelin, the total lecithin concentration, and total lecithin as a percentage of total amniotic fluid phospholipids. All three indices were compared with the lecithin/sphingomyelin ratio obtained by a chromatographic procedure. Our data suggest that measuring the percentage of total lecithin may provide the best means of evaluating fetal lung maturity, but a final judgment must await clinical investigation.

Amniotic Fluid↗