Early surgical intervention in premature infants with respiratory distress and patent ductus arteriosus

Ten premature infants with severe idiopathic respiratory distress syndrome and a large patent ductus arteriosus who underwent ligation are discussed. There were no surgical deaths, but two late deaths occurred. Three similar infants who were not operated on are also presented; all of them died. An additional forty-four such patients with ductus ligation reported on recently were reviewed.Evidence is presented that strongly supports ligation of the ductus as soon as it becomes apparent in infants with severe respirator-dependent idiopathic respiratory distress syndrome.The diagnosis of patent ductus arteriosus is reliably established clinically, and the relatively high complication rate associated with cardiac catheterization in premature infants contraindicates its use.     

The role of glucagon in the regulation of plasma lipids.

The role of glucagon in regulating plasma lipid concentrations (nonesterified fatty acids, ketone bodies, and triglycerides) is reviewed. The effects of glucagon-induced insulin secretion upon this lipid regulation are discussed that may resolve conflicting reports in the literature are resolved. In addition, the unresolved problem concerning the pharmacologic versus physiologic effects of glucagon is stressed. Glucagon's role in stimulating lipolysis at the adipocyte serves two important functions. First, it provides plasma nonesterified fatty acids for energy metabolism and secondly, it ensures substrate for hepatic ketogenesis. In vitro, glucagon's lipolytic activity has been consistently observed, but in vivo, this activity has sometimes been obscured by the effects of glucagon-induced insulin secretion. Frequently, a biphasic response has been reported in which a direct lipolytic response is followed by a glucagon-induced insulin suppression of plasma nonesterified fatty acid concentration. When the glucagon-induced insulin secretion has been controlled by various in vivo techniques, glucagon's lipolytic activity in vivo has frequently been demonstrable. In the 1960s, in vitro liver perfusion experiments demonstrated that glucagon enhanced hepatic ketogenesis independent of glucagon's lipolytic activity. However, this direct effect of glucagon on the hepatocyte was not universally accepted because of conflicting reports in the literature. Failure to observe an in vitro ketogenic effect of the hormone in some studies may have been due to suboptimal experimental conditions. Certain factors are now known to influence the ketogenic response, such as the concentration of fatty acids in the media and the nutritional status of the animal. Under optimal in vitro conditions with liver preparations from fed animals, the ketogenic response to physiologic concentrations of glucagon has been demonstrated. However, further study is necessary to define the quantitative ketogenic role of the hormone. In spite of this early in vitro work, glucagon was not definitely shown to be ketogenic in vivo (independent of fatty acid availability) both in the rat and in diabetic man until 1975. Since these observations, several reports have confirmed the ketogenic action of glucagon in vivo by direct hepatic catheterization experiments. Glucagon's role in decreasing hepatic triglyceride synthesis and secretion in vitro has been repeatedly shown but the mechanism is unresolved. This lipid regulatory action of glucagon has been more difficult to demonstrate in vivo because of the many variables that affect triglyceride synthesis. Under specific experimental conditions, however, glucagon has been shown to decrease plasma triglyceride concentration in man at both physiologic and pharmacologic concentrations. Hepatic catheterization experiments have also confirmed this effect in man. The regulation of lipids by glucagon fits well into its role as a stress hormone...     

In vivo and in vitro effects of tetrahydroisoquinolines and other alkaloids on rat pituitary function

Several tetrahydroisoquinolines (TIQs) were tested for their in vitro and in vivo capacities to modulate prolactin (PRl) and beta-endorphin (beta-end) secretion by the rat pituitary and for their abilities to displace [3H]spiroperidol and [3H]naloxone binding from pituitary and hypothalamic membranes. Receptor binding studies showed that TIQs could be classified as having (a) higher affinity for opiate receptors (tetrahydropapaverine, papaverine, 6-methylsalolinol, 1-carboxysalsolinol and 3',4'-deoxy-norlaudanosolinecarboxylic acid), (b) higher affinity for the dopamine receptor (salsolinol and 7-methylsalsolinol), or (c) approximately equal affinity for the two binding sites (6,7-dimethylsalsolinol and tetrahydropapaveroline, THP). In freely moving male rats, THP produced a several-fold increase in plasma PRL levels. This effect was not altered by co-administration of naloxone but was attenuated by dopamine. In vitro several TIQs reversed the inhibitory effect of dopamine on PRL secretion by cultured anterior pituitary cells. The order of potencies of the TIQs in this system paralleled their order of potencies in the dopamine receptor assay. THP, the most potent dopamine antagonist, also blocked dopamine-mediated inhibition of beta-endorphin secretion from neurointermediate lobe cells in culture. These data demonstrate that THP and some other TIQs can act as dopamine antagonists in radioreceptor assays, in cell culture and in vivo.     

Pulmonary Valvotomy: An Alternative Method

An alternative technique of pulmonary valvotomy for patients with pulmonary atresia and intact ventricular septum is presented. The method is simpler and safer than open valvotomy with inflow occlusion or with cardiopulmonary bypass. It is more precise and controlled than closed valvotomy.     

Effects of histrionicotoxin on the chemosensitive and electrical properties of skeletal muscle

Histrionicotoxin (HTX), a spiropiperidine alkaloid from the Colombian frog, Dendrobates histrionicus, has a variety of effects on the function of mammalian and amphibian nerve-muscle preparations. At a concentration of 70 × 10⁻⁶m, HTX blocks indirectly elicited muscle twitches in the mouse phrenic nerve-diaphragm preparation within 20 min, while potentiating directly elicited twitches. Resting membrane potential and passive electrical properties are little affected by the drug. HTX prolongs the falling phase of the action potential and blocks delayed rectification, indicating that the potassium conductance is suppressed. Endplate potentials are also blocked by the toxin, and the onset of this blockade is dependent on the frequency of stimulation. Similarly, HTX decreases the sensitivity of denervated mammalian skeletal muscles to repetitive applications of acetylcholine, the degree of blockade also being dependent on the rate and duration of iontophoretic application of acetylcholine. All effects of HTX are reversed by washing the muscle. HTX does not prevent the irreversible effects of an acetylcholine antagonist, α-bungarotoxin, in the mouse phrenic nerve-diaphragm preparation. It is suggested that HTX acts on the ionic conductance modulator of the acetylcholine receptor in a manner similar to its semisynthetic derivative perhydrohistrionicotoxin.     

Membrane cable properties of normal and dystrophic chicken muscle fibers

Values of fiber radius obtained by square pulse analysis and histological measurements indicated that the innervated dystrophic fibers which had been examined with microelectrodes were hypertrophic. The specific membrane resistance of dystrophic fibers was also greater than normal. In addition, experimentally induced compensatory hypertrophy of innervated nondystrophic (normal) fibers of the posterior latissimus dorsi led to alterations in several membrane characteristics which resulted in values resembling those of innervated dystrophic fibers. Twenty-one days after denervation, the values for the cable properties of normal and dystrophic fibers were increased, yet similar values were attained for the space constant, specific membrane resistance, and membrane capacitance. In both normal and dystrophic muscles which were denervated for 21 days the fiber radius decreased 40%. To study the mechanism underlying the increase of the specific membrane resistance after denervation, the resting membrane conductance was selectively altered. In solutions of low pH (5.0) where chloride conductance was presumably reduced, the space constant, time constant and specific membrane resistance of innervated normal and dystrophic fibers were increased and approached values obtained from 21-day denervated muscles. In contrast, solutions of low pH had no marked effects on 21-day denervated normal and dystrophic muscles. It is suggested that the increased values for these cable properties from denervated normal and dystrophic posterior latissimus dorsi muscles may be partially due to reduced potassium and chloride conductances. Furthermore, the presence of hypertorphic fibers may be a significant morphological adaptation in dystrophic muscles.     

Role of different methods of lung biopsy in the diagnosis of lung lesions

Bronchoscopic biopsy and percutaneous needle biopsy were retrospectively compared with open biopsy. No procedure resulted in mortality. Nonfatal complications were similar in incidence. Bronchoscopic biopsy approached the accuracy of open biopsy only when applied to infiltrates. Percutaneous needle biopsy approached the accuracy of open biopsy only when applied to nodules. Nonspecific results of either bronchoscopic biopsy or percutaneous needle biopsy were unacceptable as definitive diagnoses.     

Correlates of success and retention in a multifaceted,long-term behavior modification program for obese adolescent girls

A long-term weight control program for 36 obese adolescent girls was conducted by an educator, a psychologist, a physician, and a nutritionist. Two cohorts of girls participated for 12 and 7 months, respectively. Both pretest scores and changes on measures of attitudes, behavior, body image, nutritional intake, exercise, and attractiveness of photographs were used as predictors and correlates of weight change, as well as to identify subsequent dropouts. Few subjects lost large amounts of weight and 53% dropped out. Being older, having more positive attitudes toward fatness, decreasing temptation to eat in many places and situations, having a lower pretest caloric intake, and reducing intake of calories and junk food along with changing the distribution of calories from fats to carbohydrates were all associated with losing weight or staying in the program.