The activation of human plasma prekallikrein as a hemocompatibility test for biomaterials. II. Contact activation by EVAL and EVAL-SMA copolymers

The activation of human plasma prekallikrein (PKK) to kallikrein (KK), induced by the contact of blood with foreign materials, is a useful in vitro hemocompatibility test. Kallikrein is easily detected by its reaction with the chromogenic substrate H-D-Pro-Phe-Arg-pNA, which releases p-nitroaniline, revealed by its absorption at 405 nm. This test, which was already carried out by evaluating PKK activation by the 'end-point' method, has been carried out in this work by the more accurate 'initial velocity' method, i.e. by evaluating the activation from the initial rates of the KK-substrate reaction. The tests were carried out on the following materials: borosilicate glass (as a high-activation reference material), silicone (as a low-activation reference material), the commercial biomaterial Cardiothane 51, three graft copolymers synthesized in our laboratory by reacting ethylene-vinyl alcohol copolymer (EVAL) with styrene-maleic anhydride copolymer (SMA), and EVAL itself. A mathematical treatment based on a simple kinetic model has been used for a first-approximation evaluation of the PKK-activating power of the materials tested. The quite low activating power of the EVAL-SMA copolymers, which are easily processable into water-permeable hollow fibers, suggests the possibility of their use in blood dialyzers.

[Long-term non-neurologic morbidity in low birth weight infants. A 3-year follow-up]

The aim of the present work is to observe non-neurological morbidity in low-birth-weight-neonates during the first year of life, to define their predominance and to establish whether any correlation between the observed pathologies, gestational age and/or birth weight is evident. Respiratory infectious diseases were the most frequent cause of morbidity starting during the first months life. Anemia and osteopenia were significantly related to gestational age, both occurring with high frequency in babies born before 31 weeks of gestational age. In this gestational age group of neonates birth weight did not influence the incidence of the pathologies studied. On the contrary, morbidity was inversely related to birth weight when neonates of greater gestational age were considered. Candidiasis was significantly more frequent in newborn babies weighing at birth less than 2000 grams. Follow-up programs of low-birth-weight neonates give the opportunity to establish nutritional schedules fit for infants born prematurely and to provide precocious diagnosis and therapy apt to minimize infectious respiratory diseases, so often occurring in these babies.

The Jervell and Lange-Nielsen syndrome

Deafness and electrocardiographic changes (prolongation of the Q-T interval and inversion of the T wave) with a clinical picture of syncopal attacks and sudden death, were described as a distinct syndrome by Jervell and Lange-Nielsen in 1957. The syndrome is inherited as an autosomal recessive trait. In this study, all the cases reported since 1957 and their proposed prevalence are reviewed. The authors describe the 4 cases they have studied, all of which presented congenital sensorineural hearing loss and electrocardiographic changes characteristic of the syndrome. The relatively high number of cases they have encountered casts doubt on literature that states that the syndrome occurs more frequently in Northern-European populations. Consequently, it is advisable to perform an electrocardiogram in all children affected by congenital deafness.

Prejunctional GABA-B inhibition of cholinergic, neurally-mediated airway contractions in guinea-pigs

GABA is a known inhibitory neurotransmitter in the CNS. Recent studies have also demonstrated the presence of GABA in peripheral tissue, including lung. To delineate a role for GABA in lung, the effect of GABA and selective GABA agonists and antagonists on neuronally-induced airway contractions in guinea pigs were studied. In vitro, tracheal contractions induced by electrical field stimulation (EFS) were inhibited by tetrodotoxin and atropine indicating that the contractions were mediated by neuronal release of acetylcholine. The contractions caused by EFS, but not those by exogenous acetylcholine, were inhibited by GABA (EC50 = 4.5 microM) and the selective GABA-B agonist baclofen (EC50 = 9 microM), but not by the GABA-A agonist, muscimol. The inhibitory effect of baclofen was not affected by the GABA-A antagonist, bicuculline, but was significantly reversed with the GABA-B antagonists, 3-aminopropylphosphonic acid (3-APPA) (pA2 = 4.5) and 2-hydroxysaclofen (pA2 = 4.1). In vivo, vagal nerve stimulation (5 V, 20 Hz, 0.5 ms, 5 s) in anesthetized, mechanically ventilated guinea-pigs caused cholinergic-dependent bronchospasms that were inhibited by intravenous GABA (3 and 10 mg/kg) and baclofen (1-10 mg/kg), but not by muscimol. The inhibitory effects of GABA and baclofen against vagal bronchospasm were blocked by 3-APPA (5 mg/kg, i.v.), but not by bicuculline. Responses to the GABA-B agonists were unaltered after the treatment of animals with phentolamine or propranolol to block alpha-adrenergic and beta-adrenergic receptors, respectively. Bronchospasm due to intravenous methacholine was also unchanged by GABA and baclofen.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of leukotriene antagonists, lipoxygenase inhibitors and selected standards on leukotriene-mediated allergic bronchospasm in guinea pigs

Leukotrienes (LT) C4, D4, and E4 are major contributors to the pathobiology of human bronchial asthma. Therefore, it is likely that compounds that antagonize the action or inhibit the formation of LTs will be useful therapeutic agents. We have studied the effects of LT antagonists, 5-lipoxygenase inhibitors and selected standards in a model of LT-mediated allergic bronchospasm in guinea pigs. Sensitized animals were pretreated with mepyramine, indomethacin and propranolol to eliminate the influence of histamine, prostaglandins, thromboxanes and circulating catecholamines. In these animals, inhalation of antigen resulted in a bronchospasm consistent with a LT-mediated response that was slow in onset, of long duration and was inhibited by the selective LTD4, antagonists FPL-55712, LY-171,883 and ICI-198,615. ICI-198,615 was approximately 50-times more potent than FPL-55712 by the intravenous and intratracheal routes. However, of thirteen compounds known to inhibit 5-lipoxygenase and LT biosynthesis in vitro only phenidone, piriprost and AA-861 were active in this in vivo model. The allergic bronchospasm was inhibited by bronchodilators (e.g. PGE2, aminophylline and forskolin) and by some mast cell stabilizers, but was otherwise insensitive to other pharmacological classes of compounds including calcium channel blockers and antagonists of serotonin, acetylcholine and platelet-activating factor. This model seems useful and reasonably selective for the evaluation of new antianaphylactic compounds that are LT antagonists. The inactivity of many 5-lipoxygenase inhibitors in this model suggests they do not inhibit LT formation in vivo.

Prenatal cerebral Doppler ultrasonography and neonatal neurologic outcome

The significance of fetal cerebral blood flow analysis in the prediction of neonatal neurologic outcome was investigated on 87 fetuses at risk for chronic hypoxia. Blood flow velocity waveforms were recorded from the fetal internal carotid artery immediately before cesarean section; newborns underwent neurologic follow-up until discharged from the neonatal division. Neonatal outcome was considered abnormal in presence of a postasphyxial encephalopathy. Receiver operating characteristic curves were used to demonstrate the efficacy of fetal cerebral blood flow velocity waveform analysis as a predictor of neonatal outcome. A value of the pulsatility index from the internal carotid artery below the second standard deviation of our range of normality was found to be a powerful indicator of the development of neonatal neurologic abnormalities (Cohen's Kappa index = .58). These results were particularly evident in fetuses with a birthweight above 2500 g in which a specificity of 93.7%, a sensitivity of 75%, and an accuracy of 89.7% were achieved.

Antiallergy activity of Sch 37224, a new inhibitor of leukotriene formation

Sulfidopeptide leukotrienes (LTs) C4, D4 and E4 are important mediators in the pathophysiology of bronchial asthma. Sch 37224, 1-(1,2-dihydro-4-hydroxy-2-oxo-1-phenyl-1,8-naphthyridin-3-yl) pyrrolidinium, hydroxide inner salt, has been found to inhibit the formation of these autocoids. Although Sch 37224 did not inhibit 5-lipoxygenase, cyclooxygenase or phospholipase A2, it inhibited LTD4 and thromboxane B2 release by anaphylactic guinea pig lung (IC40 = 3.9 and 1.9 microM, respectively). At 5 microM Sch 37224 also inhibited superoxide anion radical generation from activated human polymorphonuclear neutrophilic leukocytes. When administered p.o. to guinea pigs, Sch 37224 decreased a LT-mediated allergic bronchospasm (ED40 = 1.1 mg/kg) for 6 hr and did not exhibit tolerance. In addition to its activities in allergen-induced bronchospasm in guinea pigs, Sch 37224 also inhibited hyperventilation-induced bronchospasm in guinea pigs at 0.5 to 5 mg/kg and anaphylactic bronchospasm in rats at 0.1 to 10 mg/kg. Sch 37224 was weak or ineffective as an antagonist of histamine, methacholine, serotonin, LTC4 or platelet activating factor induced bronchospasms in guinea pigs. Also, Sch 37224 was not a bronchodilator or calcium influx blocker and had only weak relaxant activity on guinea pig trachea in vitro (IC40 = 51 microM). Sch 37224 is, therefore, a potential antiallergic agent that inhibits LT release. It is p.o. effective in animal models of allergic and nonallergic-mediated bronchospasms.

Outbreak of acute rheumatic fever in northeast Ohio

An outbreak of acute rheumatic fever in 23 patients was seen in northeastern Ohio in 1986, with polyarthritis (78%) and carditis (30%) the major manifestations. Results of a questionnaire completed by the parents of all 23 patients indicated that they were generally nonindigent, with good access to medical care, and from a nonurban setting. Records of inpatients with acute rheumatic fever were reviewed for the 10 years prior to 1986. The clinical manifestations in inpatients from 1976 to 1985 were not significantly different from those of inpatients seen during 1986. Similar outbreaks have been reported elsewhere, and physicians should be aware of a possible resurgence of classic acute rheumatic fever and ensure compliance with an adequate course of therapy for patients with streptococcal pharyngitis.

Labetalol protects against the potentiation by propranolol of the bronchospasm to norepinephrine in guinea-pigs

The increase in airway obstruction observed in asthmatics after treatment with beta-adrenergic blockers may be attributed to an unopposed alpha-adrenergic activity. Labetalol is an antihypertensive agent with beta-adrenoreceptor and alpha-adrenoreceptor blocking properties. Labetalol does not cause a bronchospasm in human asthmatics. Norepinephrine (0.025-0.1 mg/kg, i.v.) caused a bronchospasm in guinea-pigs after the blockade of beta-adrenoreceptors with propranolol (0.1-1 mg/kg, i.v.), but not after beta-blockade with labetalol (0.1-10 mg/kg, i.v.). Labetalol significantly protected against the bronchospasm induced by norepinephrine in the presence of propranolol. The bronchospasm induced by norepinephrine was inhibited by alpha-adrenergic blockade with phentolamine (0.03-3 mg/kg, i.v.), but not by blockade of receptors for histamine, acetylcholine or sulfidopeptide leukotrienes or by inhibition of cyclooxygenase activity. The lack of a bronchospasm after stimulation of alpha 2-receptors with B-HT 920 suggests that the bronchospasm to norepinephrine was due to the activation of alpha-adrenoreceptors on airway smooth muscle. The more desirable pulmonary profile of labetalol compared with other beta-blockers may be due, in part, to the interaction of labetalol with both beta- and alpha-adrenoreceptors.

The prevalence of psychosocial problems. A study of 37,678 Sydney adults

Australian household surveys have indicated the prevalence of emotional or psychological disturbance as about 25 per cent of the population. Among those attending general practitioners' surgeries, the prevalence is even higher - 33 to 40 per cent. Morevoer, such psychosocial problems have an important effect on people's mental and physical health.

Heavy drinkers--their prevalence, attitudes and characteristics

Heavy drinkers were defined as those admitting to drinking six or more drinks every day or most days. This pattern of alcohol consumption which is equivalent to 80 or more grams of ethanol per day, puts them at 'high risk' of physical and/or psychosocial complications. Eleven percent of 23,673 males and 1% of 19,803 females who had a Medicheck screening were heavy drinkers. The most frequent reasons given for heavy drinking were relaxation, social contact and enjoyment of the taste. Most heavy drinkers felt that they drank more than was good for them but did not consider themselves to be 'sick' people in need of treatment. Heavy drinkers had a higher prevalence of psychosocial problems than moderate or light drinkers.