Monoclonal Antibodies against Leucoagglutinin-Reactive Human T-Lymphocyte Surface Components

The binding specificities of three biologically active anti-lymphocyte monoclonal antibodies (MoAb) (K46M, K3G, and 3-19-2) produced against human T-cell surface components reactive with the mitogenic lectin leucoagglutinin from Phaseolus vulgaris (La) were analysed. K46M is a strong T-cell mitogen, while K3G and 3-19-2 inhibited cell-mediated cytotoxicity. Resting peripheral blood lymphocytes (PBL) contained 4-16% K46M+ cells, 8-35% K3G+ cells, and less than 0.3-4% 3-19-2+ cells. After stimulation with T-cell mitogens the proportion of K46M+ and 3-19-2+ cells increased markedly (mean 59 and 30% positive cells, respectively), while the increase in K3G+ cells was less prominent (38%). K46M-reactive structures were expressed on mature T cells and probably also on B cells. K3G reacted with B and T cells while 3-19-2 showed a broader specificity reacting also with erythrocytes. All three MoAb reacted with lipid extracts of resting and activated PBL as well as with purified neutral glycolipids of lymphoid origin. In addition 3-19-2 reacted with lipid extracts of erythrocytes. K46M immuno-precipitated four surface peptides from lectin-stimulated PBL. Their apparent molecular weights were 53,000, 42,000, and 16,000 (doublet). The 53,000 and 42,000 MW peptides were identified as the alpha and beta chains of the T-cell antigen receptor. The identity of the 16,000 MW peptides is presently unknown. K3G and 3-19-2 did not specifically precipitate any lymphocyte surface peptide.     

Effect of nicotine infusion in humans on platelet aggregation and urinary excretion of a major thromboxane metabolite

The objective of this study was to evaluate further a possible role of nicotine as a stimulator of platelet aggregability and platelet arachidonic acid metabolism in vivo. In six healthy, non-smoking males, platelet aggregability was assessed by filtragometry and impedance aggregometry before, during and after an intravenous infusion of nicotine at two different doses (0.25 and 0.5 μg kg^-1 min^-1) for 30 min. The aggregatory response was also measured after the addition of nicotine at final concentrations ranging from 10^-11 mol L^-1 to 10^-5 mol L^-1 directly to the aggregating blood. The synthesis of thromboxane A₂ (TxA₂) in platelets was estimated by quantitating the urinary excretion of 2,3-dinor-thromboxane B₂ (Tx-M). Despite the plasma concentrations of nicotine, cotinine and catecholamines in the range of those occurring during acute cigarette exposure, the excretion of Tx-M (204±36 pg mg^-1 creatinine) remained unaltered during nicotine infusion. Similarly, platelet aggregatory response to collagen was not influenced by nicotine when infused or added in vitro. However, an enhanced aggregability was detected by filtragometry during the infusion of nicotine at the higher dose employed. The results indicate that nicotine, infused at moderate doses, produces a weak platelet stimulation that is not accompanied by significant release of thromboxane A₂, as monitored by urinary excretion of Tx-M. Although a direct action of nicotine on platelets cannot be excluded, it appears more likely that the enhancement of platelet function is mediated by other, secondary mechanisms.     

Effects of a-adrenoceptor subtype-selective antagonists on the human saphenous vein in vivo

The effects of the α-adrenoceptor subtype-selective antagonists prazosin (α¹) and yohimbine (α₂) on the saphenous vein of six healthy male subjects were investigated in vivo. The drugs were infused locally into the congested (40 mmHg), long saphenous vein constricted by simultaneous local infusion of noradrenaline (NA). Prazosin 10^-9 M (concentration in the infusion solution, infusion rate 0.3 ml min^_I) did not reduce the NA-induced venoconstriction, but at a concentration of 10^-8 M there was a significant reduction; in two subjects no response to NA could be elicited in the presence of 10^-8 M prazosin. Prazosin 10^-7 M caused no further reduction of the NA effect compared to that produced by 10^-8 M in three of the subjects, whereas in one, prazosin 10^-9, 10^-8 and 10^-7 M caused a dose-dependent blockade. Yohimbine, 10^-9, 10^-8 and 10^-7 M caused a dose-dependent reduction of the NA-induced venoconstriction in all subjects. The results suggest that the human saphenous vein is endowed with functionally important populations of both α₂- and a₁-adrenoceptors.     

Acute continuous exposure to cigarette smoke produces discrete changes in cholecystokinin and substance P levels in the hypothalamus and preoptic area of the male rat

FUXE, K., SIEGEL, R.A., ANDERSON, K., ENEROTH, P., MASCAGNI, F. & AGNATI, L.F. 1985. Acute continuous exposure to cigarette smoke produces discrete changes in cholecystokinin and substance P levels in the hypothalamus and preoptic area of the male rat. Acta Physiol Scand 125, 437–443. Received 8 January 1985, accepted 7 May 1985, TSSN 0001–6772. Department of Histology, Karolinska Institute, Stockholm, Sweden, Research and Development Laboratory, Department of Obstetrics and Gynaecology, Karolinska Hospital, Stockholm, Sweden, Deutsches Primaten Zentrum, Gottingen, FRG, and Department of Human Physiology, University of Modena, Italy. By means of a Walton Horizontal Smoking Machine, male rats were exposed to the smoke from 1–4 cigarettes burned in a continuous fashion. Cholecystokinin (CCK) and substance P levels (determined by means of radio-immunoassay) were measured in discrete hypothalamic and preoptic regions. Acute continuous exposure to cigarette smoke induced increases in CCK levels in the paraventricular hypothalamic region as well as decreases in CCK levels in the median eminence. Furthermore, this treatment resulted in decreased CCK and substance P levels in the medial preoptic region. The results have been interpreted to indicate that CCK and substance P containing neuronal systems can be regulated by cholinergic nicotine-like receptors.     

Spectral turbulence analysis of the signal-averaged electrocardiogram for predicfing inducible sustained monomorphic ventricular tachycardia in patients with and without bundle branch block

Spectral turbulence analysis of the signal-averaged electrocardiogramis a new method for identifying patients prone to sustainedmonomorphic ventricular tachycardia. In contrast to analysisin the time domain, it has been claimed to be applicable inpatients with bundle branch block. The aim of this study wasto assess the predictive value of spectral turbulence analysis,in relation to the inducibility of sustained monomorphic ventriculartachycardia, in patients with and without bundle branch block.One hundred and sixty nine patients, of whom 120 had a QRS duration 120 ms, were studied Forty-seven patients had inducible sustainedmononwrphic ventricular tachycardia and were compared to 122control patients. The overall sensitivity of the spectral turbulenceanalysis for predicting inducible ventricular tachycardia was77%, the spectficity 35% and the total predictive accuracy 47%.The limited predictive accuracy was mainly due to a lack ofd between patients with and without ventricular tachycardiain patients with a QRS duration 120 ms. In patients with QRS 120 ms, however, there were significant differences in allspectral turbulence parameters and the method had a sensitivityof 75%, a specificity of 72% and a total predictive accuracyof 73%. The diagnostic usefulness of spectral turbulence analysis isdependent upon normal QRS duration and the method is applicableonly to patients without bundle branch block.     

Guidelines for the management of traumatic dental injuries. I. Fractures and luxations of permanent teeth

Crown fractures and luxations occur most frequently of all dental injuries. An appropriate treatment plan after an injury is important for a good prognosis. Guidelines are useful for delivering the best care possible in an efficient manner. The International Association of Dental Traumatology (IADT) has developed a consensus statement after a review of the dental literature and group discussions. Experienced researchers and clinicians from various specialties were included in the group. In cases where the data did not appear conclusive, recommendations were based on the consensus opinion of the IADT board members. The guidelines represent the current best evidence, based on literature research and professional opinion. In this first article of three, the IADT Guidelines for management of fractures and luxations of permanent teeth will be presented.