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Biomedical subjects

L Stein

Publications and source records attributed to L Stein.

At least 145 records · Page 8Linked to original sources
PubMed1976

The interaction of the lung and chest wall in dogs.

The deformation of the lung by the chest wall was observed on radiographs of the ribs and interspaces and on morphologic preparations of samples cut from the frozen thorax. The effect of these deformities on the distribution of ventilation and regional lung volume of the underlying lung was determined using Xenon 133. We found that ribs and interspaces deform the lung surface with different radii of curvature, suggesting local differences in pleural pressure and that traction on the thoracic limb caused deformities in the underlying interspaces which were similar to those produced by 20 cm H2O mouth pressure. Xenon 133 showed that these changes in pressure had no effect on the regional volume or on ventilation distribution in the underlying lung. We conclude that changes in pleural pressure produced by localized deformities exert their effect close to the deformity and that the underlying lung responds to the average pressure exerted over a much larger area of the pleural surface.

Airway Resistance↗
PubMed1976

Linguistic performance in vulnerable and autistic children and their mothers.

The authors studied the language patterns of schizophrenic mothers and their 4-year-old children, and compared them with the speech of normal mothers and children and normal mothers with autistic children. They found that children of schizophrenic mothers showed lags in language development and language distortions less severe than but in some ways similar to those seen in autistic children. Schizophrenic mothers were more likely to produce more deficient and/or distorted language in interactions with their children. Mothers of autistic children produced language that was equal to or above that of mothers of normal children on most parameters and adjusted their language to the chronological rather than the linguistic age of the child.

Autistic Disorder↗
PubMed1976

Relationship between pulmonary hemodynamics and arterial pH and carbon dioxide tension in critically ill patients.

To ascertain the clinical significance of derangements in arterial pH and arterial carbon dioxide tension (PaCO2) in modifying pulmonary arterial pressures and pulmonary vascular resistance in critically ill patients, the relationship between these two sets of variables was evaluated in 75 patients. No significant differences in pulmonary hemodynamic values were found among patients with acidemia, a normal pH, or alkalemia, even at extreme pH values; and there was no consistent relationship between PaCO2 and each of the pulmonary hemodynamic measurements. In patients who initially had a normal pH but subsequently developed acidemia or alkalemia, there was also no significant correlation between changes in pH and pulmonary hemodynamic values. We conclude that abnormalities of pulmonary hemodynamic values in seriously ill patients are usually due to factors other than acid-base derangements. Of practical importance is the observation that the predictability of the pulmonary arterial wedge pressure from the pulmonary arterial diastolic pressure is not invalidated by acid-base disturbances.

Acid-Base Imbalance↗
PubMed1975

Neurochemical regulation of feeding in the rat: facilitation by alpha-noradrenergic, but not dopaminergic, receptor stimulants.

Rats ate voraciously after intraventricular injections of the alpha-noradrenergic receptor stimulant clonidine. Intraventricular administration of l-norepinephrine also facilitated feeding, but similar injections of dopamine and apomorphine (a dopamine receptor stimulant) were ineffective and even tended to suppress feeding. Clonidine was 100 times more potent than norepinephrine and increased the intake of both the ordinary diet of powdered food and a highly palatable wet food. The anorexic action of amphetamine was reversed by centrally administered clonidine. These observations suggest "respondent" rather than "operant" regulation of feeding by noradrenergic systems. That is, in relation to noradrenergic mechanisms, feeding appears to be a respondent which is sensitized or disinhibited by activation of alpha-noradrenergic receptors, rather than an operant which is reinforced by the release of norepinephrine.

Adrenergic alpha-Agonists↗
PubMed1975

Z protein in hepatic uptake and esterification of long-chain fatty acids.

Fatty acids radioactivity was bound to Z protein in liver after administration of['3H]oleate to rats or to a perfused rat liver preparation. Pretreatment withflavaspidic acid (340 mumol/kg), a potent inhibitor of fatty acid binding to hepatic Zprotein in vitri, effectively reduced oleate radioactivity bound to Z by 90.2 plusor minus 4.3% and 85.0 plus or minus 6.2% in the intact rat and perfused liver, respectively. In spite of this effect, pretreatment of rats with flavaspidic acid did notalter plasma clearance, hepatic uptake, and esterification of ['3H]oleate. In contrast, in the perfused liver preparation, infusion of flavaspidic acid (340 mumol/kg)or bromosulphalein (360 mumol/kg) increased uptake of ['3H]oleate at least twofold,and oleate esterification was decreased by 15-30%. These results suggest that the binding of long-chain fatty acids to Z protein is not an obligatory step in their uptakeby the liver and that Z protein may be involved in fatty acid esterification.

Animals↗
PubMed1975

Pulmonary edema related to changes in colloid osmotic and pulmonary artery wedge pressure in patients after acute myocardial infarction.

Pulmonary artery wedge and plasma colloid osmotic pressures and their relationship to pulmonary edema were investigated in 26 patients with acute myocardial infarction of whom 14 developed pulmonary edema. In the absence of pulmonary edema, both the pulmonary artery wedge pressure and plasma colloid osmotic pressure were in normal range; after onset pulmonary edema, a moderate increase in pulmonary wedge pressure and reduction in plasma colloid osmotic pressure were observed. When the gradient between the plasma colloid osmotic pressure and the pulmonary artery wedge pressure was calculated, highly significant differences were demonstrated (P less than 0.002). In the absence of pulmonary edema, this gradient averaged 9.7 (plus or minus 1.7 SEM) torr; following appearance of pulmonary edema, it was reduced to 1.2 (plus or minus 1.3) torr. During therapy with digoxin and furosemide, reversal of pulmonary edema was closely related to a concomitant change in the colloid osmotic-hydrostatic pressure gradient. These observations indicate that both increases in pulmonary capillary pressure and decreases in colloid osmotic pressure may follow the onset of pulmonary edema. Such decline in colloid osmotic pressure and especially the reduction in colloid osmotic-hydrostatic capillary pressure gradient may favor transudation of fluid into the lungs.

Adult↗
PubMed1975

Pulmonary edema during volume infusion.

The relationship between left ventricular filling pressure and plasma colloid osmotic pressure to pulmonary edema was examined in a group of 37 patients, the majority of whom were hypovolemic. Sixteen patients developed pulmonary edema during fluid infusion. In the 21 patients who did not develop pulmonary edema, the left ventricular filling pressure was slightly elevated but the colloid osmotic pressure was not reduced. The majority of these patients were treated with colloid solutions (group I). In five of the 16 patients who developed pulmonary edema, the left ventricular filling pressure was elevated and there was no reduction in the plasma colloid osmotic pressure. These patients received only colloids (group II). In the other 11 patients who developed pulmonary edema, the left ventricular filling pressure was normal but the plasma colloid osmotic pressure was reduced to 16 +/- 2 torr (group III). The colloid osmotic pressure in this group was significantly less than in the other two groups (P less than 0.01). Most of these patients received large volumes of crystalloid solutions. After administration of furosemide, clearing of pulmonary edema in this group was associated with normalization of the plasma colloid osmotic pressure. Infusion of large volumes of crystalloids in hypovolemic patients can be hazardous, for reduction of the plasma colloid osmotic pressure may predispose to the development of pulmonary edema even when the left ventricular filling pressure remains normal.

Adult↗
PubMed1975

Reducing emotional distance: a new method to teach interviewing skills.

Following an extensive review of the literature on the teaching of interviewing to medical students and psychiatry residents, the authors conclude that too much teaching emphasis has been given to the content of the interview and not enough to the process of the interview. A new method to teach interviewing skills to residents in psychiatry is described. The method focuses entirely on the interpersonal aspects of the interview. Within a seminar format, each resident attempts to reduce the "emotional distance" between himself and a patient. Much consideration is given to the individual emotional style of the resident. Through practice with this method and with peer and staff feedback, each resident who was studied improved in this ability, gained much affectual information from the patient, and learned many of the subtle aspects of process that are necessary for good interviewing and good psychotherapy.

Communication↗
PubMed1975

Effects of benzodiazepines on central serotonergic mechanisms.

If the rat conflict test were a valid animal model of anxiety neurosis, evidence which implicates serotonin systems in the anxiety-reducing actions of benzodiazepine tranquilizers could be summarized as follows: (1) The punishment-lessening effects of benzodiazepines in the conflict test are mimicked by serotonin antagonists (methysergide, cinanserin, bromolysergic acid), serotonin synthesis inhibition (PCPA), and serotonin nerve terminal damage (5,6-dihydroxytryptamine). (2) Punishment effects may be intensified by the serotonin precursor, 5-hydroxytryptophan (in combination with a monoamine oxidase inhibitor), serotonin agonists (alpha-methyltryptamine), or intraventricular injections of serotonin itself. Intraventricularly administered serotonin also antagonizes the punishment-lessening effects of benzodiazepines. (3) Stimulation of the serotonergic cell bodies in the dorsal raphe nucleus by local application of crystalline carbachol causes intense suppression of behavior. The suppressive effects of raphe stimulation are antagonized by systemic administration of benzodiazepines. (4) In biochemical experiments, the decrease in norepinephrine turnover induced by oxazepam rapidly undergoes tolerance, whereas the decrease induced in serotonin turnover is maintained over repeated doses. These results parallel findings in the conflict test which indicate that the depressant action of oxazepam rapidly undergoes tolerance, whereas the anxiety-reducing action is maintained over repeated doses. Although central serotonin neurons are thus implicated in the therapeutic actions of benzodiazepine tranquilizers, it is quite possible that the drugs actually act indirectly to reduce serotonin activity. The concept that benzodiazepines may exert a primary action on GABA-containing neurons, which in turn regulate serotonergic transmission, was supported by preliminary psychopharmacological evidence. The GABA-antagonist picrotoxin, at doses that do not disrupt unpunished behavior, fully antagonizes the punishment-lessening effects of benzodiazepines in the conflict test.

Animals↗