Brain endorphins: possible role in reward and memory formation

A role for enkephalin in the mediation of behavioral reinforcement is supported by several lines of evidence: i) central injections of enkephalin serve as reinforcement for self-administration behavior, ii) electrical stimulation of many enkephalin-rich regions serves as reinforcement for self-stimulation behavior, which is blocked by moderate doses of naloxone, and iii) long-term retention of a passive avoidance response is facilitated by immediate post-learning injections of methionine-enkephalin and morphine.

[Electric shock waves crushing stones in the exposed kidney (author's transl)]

Highenergy shock waves can desintegrate human calculi of the kidney into fine fragments without direct contact. A closed reflector system which allows sterile contact with the exposed kidney is presented.

Approximate steady-state properties of lattices of interacting three-state enzyme molecules: a novel phase transition

Previous work on the cooperative behavior of lattices of interacting two-state enzyme molecules at steady state is extended here to interacting three-state enzyme molecules with a one-way cycle. The Bragg-Williams (mean field) approximation is used. A phase-transition example with a bifurcation point is discussed. Compared to conventional phase transitions (with a van der Waals loop), several new and complicated features appear. A second paper on this subject will contain a number of other examples of three-state systems.

Pharmacology of lorazepam

Lorazepam reduced conflict behavior in rats and monkeys, inhibited pentylenetetrazol- and electroshock-induced convulsions, suppressed footshock-induced fighting behavior, and prevented morphine-induced stimulation in mice at lower doses than other benzodiazepines tested. This behavioral profile suggests that lorazepam will be an active anti-anxiety agent in man at low doses.

Postoperative biopsy of the common bile duct via the T-tube tract

We describe our experience with the first reported cases of postoperative common bile duct forceps biopsy via a postoperative T-tube tract. Bronchial forceps biopsies were performed on two patients with fixed postoperative filling defects in the common bile duct. Because of possible complications, caution is recommended in employing this technique. Common bile duct diagnostic brushing and stricture dilatation, as well as choledochoscopy, are envisaged as further diagnostic and therapeutic tools for the radiologist.

Possible role of dopamine-beta-hydroxylase in the regulation of norepinephrine biosynthesis in rat brain

In Experiment 1, the dose-response effects of three dopamine-beta-hydroxylase (DBH) inhibitors (diethyldithiocarbamate, FLA-63 and U-14, 624) on the endogenous levels of norepinephrine and dopamine in pons-medulla of rat brain were determined. In Experiment 2, the effect of low doses of diethylithiocarbamate (2.5 to 120 mg/kg) on the level of norepinephrine-3H produced from dopamine-H3 was determined. The data obtained by extrapolation of the curves in both experiments provided an estimation of the in vivo level of DBH activity and suggested that it was not present in excess. Finally, in Experiment 3, the three DBH inhibitors reduced self-stimulation (a behavior dependent upon catecholamines) in a dose-related manner and intraventricular injections of 1-norepinephrine reinstated normal rates of self-stimulation. The results from the three experiments are consistent with the idea that DBH is involved in the regulation of norepinephrine biosynthesis. The relationship of this finding to our earlier report of a deficit of DBH in post-mortem brains of schizophrenics is discussed.

Benzodiazepines: behavioral and neurochemical mechanisms

The therapeutic effects of benzodiazepines in psychoneurosis may depend in part on their ability to release or disinhibit a patient's anxiety-suppressed gratification-seeking behavior. Benzodiazepines may disinhibit behavior by reducing the activity of serotonin (and possibly acetylcholine) neurons in the brain's "punishment" system. Reduction of serotonin transmission may be due to a facilitation of gamma-aminobutyric acid (GABA)-mediated presynaptic inhibition at the serotonin nerve terminal.

The psychiatrist's management of patients with undiagnosed brain neoplasm

Of 679 patients with brain neoplasms admitted to either a medical school center or a community hospital during a nine-year period, 24 had been examined by a psychiatrist before definitive diagnosis of brain neoplasm. These 24 cases were studied to evaluate the role of the psychiatrist in the management of the patients before the neoplasm was diagnosed. Such cases pose many subtle problems for psychiatrists. However, ten of the 24 patients either were sent for definitive tests by the psychiatrist with the tentative diagnosis of brain neoplasm or were triaged to other consultants to pursue that diagnosis.

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.

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.

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.

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.

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.

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.

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.