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Biomedical subjects

M Segal

Publications and source records attributed to M Segal.

At least 325 records · Page 18Linked to original sources
PubMed1977

Analysis of discrepancies between VCG and ECG interpretation of anterior wall myocardial infarction.

In 247 cases in which an old anterior myocardial infarction (MI) was suspected and in which SVEC III-lead system vectorcardiograms (VCGs) and matching conventional 12-lead electrocardiograms (ECGs) were available, records were analyzed to investigate the diagnostic agreement or discrepancy between the two techniques. The frequency of agreement (155 cases) exceeded the frequency of disagreement (92 cases), but the frequency of disagreement even with lumped subgroups was high. Eighty percent of this disagreement was between positive VCG and negative ECG diagnostic consensus. The positive MI group by ECG diagnosis showed smaller R waves and larger S waves and larger S waves in leads V2 and V3 and smaller R/S ratios in leads V2 and V4 than the negative MI groupe by ECG, while small R waves or QS patterns and large S waves in just lead V1 were the only positive finding in the positive MI group by VCG. The important VCG characteristic for positive MI diagnosis was abnormal posterior deviation of the initial QRS vectors. The high incidence of discrepancies shown by positive VCG and negative ECG diagnoses resulted from the fact that, in spite of the presence of a fairly well developed R wave in precordial leads, the initial QRS vectors were displaced posteriorly. In 8 of 18 cases classified into negative VCG and positive ECG diagnostic group, poor R wave progression did not necessarily result in the posterior displacement of the initial QRS vectors. In contrast to the difficulties in applying ECG criteria for anterior MI (variability of QRS patterns in precordial leads), an orthogenal VCG (representing the phasic changes in the depolarization process) seems to clarify the equivocal situation in the ECG diagnosis of MI.

Electrocardiography↗
PubMed1977

Prediction of renal allograft rejection by direct lymphocyte blastogenesis assay.

In an effort to better predict renal allograft rejection, lymphocyte blastogenesis (DLBA) was determined in 65 patients after transplants. Of 47 clinically diagnosed rejection episodes 45 had an associated DLBA peak which preceded the clinical diagnosis by an average of 4 days; 11 recipients had DLBA peaks not associated with rejection episodes. Of 14 recipients with multiple DLBA peaks during postoperative periods of nonfunction, none did well. The blastogenesis assay was not a reliable enough predictor of graft rejection to be used as an indication for early elevation of corticosteroid dosage.

Graft Rejection↗
PubMed1977

Prenatal diagnosis of genetic disease. A report on 200 amniocenteses.

The results of 200 prenatal diagnoses following amniocentesis are summarized. The routine withdrawal of 40 to 45 ml amniotic fluid caused no increase in maternal morbidity, fetal loss, prematurity or congenital malformations. There were no culture failures and in all cases in which amniotic fluid was obtained the prenatal diagnosis was subsequently confirmed. Electron microscopy was used in the prenatal diagnosis of a newly described metabolic storage disease (mucolipidosis IV). Eleven abnormal fetuses and one male fetus at risk for hemophilia A were diagnosed and aborted.

Abortion, Induced↗
PubMed1976

The action of norepinephrine in the rat hippocampus. III. Hippocampal cellular responses to locus coeruleus stimulation in the awake rat.

The behavioral and physiological effects of electrical stimulation of the nucleus locus coeruleus (LC) were studied in the awake rat. LC electrodes consistently supported high rates of self-stimulation (SS). LC stimulation also inhibited spontaneous cellular discharges in the hippocampus (HPC). Both the LC-induced inhibition of HPC units and the LC-evoked SS behavior were antagonized by alpha-methyltyrosine and 6-hydroxydopamine. In addition, chlorpromazine and diethyldithiocarbamate antagonized LC-induced inhibition of HPC units. D-Amphetamine facilitated SS behavior and reduced spontaneous HPC unit activity. The reinforcing properties of LC stimulation correlate closely with inhibition of cellular activity in the hippocampus; both actions appear to be mediated by norepinephrine.

Animals↗
PubMed1976

The action of norepinephrine in the rat hippocampus. IV. The effects of locus coeruleus stimulation on evoked hippocampal unit activity.

Activity of neurons in the hippocampus (HPC) was recorded in awake, freely moving rats. Most cells were inhibited by either a loud auditory stimulus (tone) or by electrical stimulation of the nucleus locus coeruleus (LC). The inhibitory responses to the tone were antagonized by drugs that interfere with central noradrenergic transmission. When LC stimulation was used as the unconditioned stimulus in a classical conditioning paradigm, previously inhibitory responses to the tone were reinstituted. When behaviorally subthreshold LC stimulation preceded a tone which was correlated with food, the existing conditioned response to the tone was potentiated. These data suggest that the generalized inhibitory response of HPC neurons to a tone is modulated by the noradrenergic pathway and that experimental activation of LC can potentiate HPC responses to behaviorally significant conditioned stimuli.

Animals↗
PubMed1976

Clinical and laboratory evaluation of elderly patients with heterophil-antibody positive infectious mononucleosis. Report of seven patients, ages 40 to 78.

Clinical, hematologic, biochemical and serologic data are recorded in seven patients aged 40 to 78 years with heterophil-antibody positive infectious mononucleosis (HA+IM). Clinical observations included fever of 22 to 30 days' duration (five of seven patients), sore throat (six of seven patients), myalgia (five of seven patients) and prominent lymph adenopathy (two of seven patients). Initial blood smears revealed significant numbers of atypical lymphocytes in only five of seven patients; however, or serial testing, in the remaining two patients Downey cells developed to a degree seen in most young adult patients with infectious mononucleosis. Comparison of liver function data from these and younger patients suggests that abnormalities tend to be more marked in those in the older than in those in the younger age range. Serologic tests confirmed primary Epstein-Barr virus (EBV) infections in all seven patients based on detection of IgM antibodies to EB viral capsid antigen in specimens obtained early, but not late, in the course of the infection, transitory antibody responses to the D (diffuse) component of the EMB-induced early antigen complex, and the initial absence and later development of antibodies to the EBV-associated nuclear antigen. Thus, the serologic data did not differ from those seen in younger patients. These results show that infectious mononucleosis should be included in the differential diagnosis of fever, sore throat and myalgia with or without significant cervical adenopathy in elderly persons.

Adolescent↗
PubMed1976

Glutamate antagonists in rat hippocampus.

1 Hippocampal cellular responses to acidic amino acids and some of their antagonists were measured in the rat anaesthetized with urethane. The effects of these antagonists of the field responses of the rat hippocampus to afferent stimulation were measured in acute as well as chronically prepared rats. 2. Hippocampal pyramidal cells were excited by microiontophoretic application of glutamate and aspartate. These responses were antagonized by glutamic acid diethyl ester (GDEE), glutamic acid dimethyl ester (GDME) and by proline. Partial specificity could be seen as excitatory responses to acetylcholine were less susceptible to the antagonists. 3 field responses of the hippocampus to commissural stimulation were reduced significantly in both an acutely prepared or the conscious rat following parenteral administration of GDEE and GDME but not proline. Responses to perforant path stimulation were not affected by these drugs. 4 It is suggested that an acidic amino acid may serve as a neurotransmitter in the commissural path to-area CA1 of the dorsal hippocampus.

Acetylcholine↗
PubMed1976

Brain stem afferents to the rat medial septum.

1. Activity of neurones in the medial septal nucleus and the diagonal band was recorded from urethane anaesthesized rats. Responses of the cells to electrical stimulation of the raphe nuclei and nucleus locus coeruleus (LC) were measured. 2. LC stimulation caused a long latency, 30-100 msec, and long duration, 100-300 msec cessation of spontaneous activity of most recorded neurones. When bursting-type neurones were recorded, the stimulation occasionally caused a synchronized repetitive bursting firing pattern. 3. Pre-treatment with drugs which interfere with catecholamine neurotransmission, i.e. reserpine and 6OHDA, prevented the appearance of cellular responses to LC stimulation. 4. Stimulation of the dorsal or the median raphe nuclei generated more complex and less clear-cut responses. These included several types of long (20-50 msec) and short (2-5 msec) latency responses. These responses were also accompanied in some cells by synchronized repetitive bursting. 5. Interference with serotonin neurotransmission with PPCA or reserpine reduced the detection of long latency responses. 6. Short latency responses accompanied by evoked field potentials were recorded also after stimulation of dorsal tegmental nucleus. 7. Rates of spontaneous firing cells were augmented after monoamine neurotransmission interruption whereas after fornix lesion, when there is supposedly an increased monoamine innervation of the septum, cells fire at lower rates than normal. 8. It is suggested that noradrenaline and serotonin may serve as neurotransmitters in the medial-septum-diagonal band areas.

Action Potentials↗