Magnesium sulfate neither potentiates nor inhibits tissue plasminogen activator-induced thrombolysis

BACKGROUND: Increasing circulating magnesium concentrations to 2-fold over normal baseline may afford a neuroprotective effect in patients with acute cerebral ischemia. OBJECTIVES: As patients receiving magnesium sulfate (MgSO(4)) in human clinical trials may also be candidates for subsequent thrombolytic therapy with tissue plasminogen activator (t-PA), preclinical assessment of possible inhibition or potentiation of fibrinolytic activity by MgSO(4) has important clinical relevance. METHODS: We utilized an in vitro system, in which D-dimer release served as a reflection of t-PA-induced clot lysis, to measure the effect of magnesium at the target concentration being tested in human stroke clinical trials, and at 2- and 3-fold higher levels. Clots from normal volunteers were exposed to t-PA at concentrations that correspond to therapeutic or endogenous plasma t-PA levels. RESULTS: MgSO(4) had no effect on t-PA-induced clot lysis at up to 3-fold target magnesium concentration (6x normal serum concentration). CONCLUSIONS: MgSO(4) concentrations well above the targeted level in therapeutic stroke trials does not affect t-PA-induced fibrinolytic activity, and therefore is a suitable agent for trials of combined neuroprotective and thrombolytic therapy in patients with acute ischemic stroke.     

Reduced platelet glutathione peroxidase activity and serum selenium concentration in atopic asthmatic patients

Background Asthmatic inflammation results in increased oxygen free radical generation and assessment of the activity of the selenitim (Se) dependent anti-oxidant enzyme, glutathione peroxidase (GSH-Px) in asthma may therefore be important. Objective To test the hypothesis that reduced GSH-Px activity and Se intake contribute to asthmatic infiammation, platelet and whole blood GSH-Px activities and serum and whole blood Se concentrations were measured and compared in atopic and non-atopic asthmatic patients and non-asthmatic control subjects. Methods GSH-Px activities of whole blood and isolated platelets were assessed in 41 asthmatic patients (33 atopic) and 41 age- and sex-matched non-asthmatic sttbjects (15 atopic) by spectrophotometric assay based oti the oxidation of NADPH. Se concentrations were determined by semi-automated fluorimetric assay. Results Mean (± sd) platelet GSH-Px activity was lower in asthmatic (89.5 ± 45.7 μmol NADPH oxidized min^?1 g^?1 of protein) than in non-asthmatic subjects (109,9 ± 41.9; P= 0.038) and in atopic (89.7 ± 45.1, n = 48) compared with non-atopie subiects (113.7 ± 40.9, n= 34: P= 0.016). Mean whole blood GSH-Px activity was also lower in atopic (12.2 ± 5.2 μmol NADPH oxidized min^?1 g^?1 of Hb) than in non-atopic subjects (14.5 ± 4.2; P= 0.038). In non-asthmatic subjects, the mean whole blood GSH-Px activity was lower in men (9.9 ± 3.5) than in women (14.5 ± 3.7; P = 0.0004) and was positively correlated with age (r= 0.51; P = 0.0006). Mean serum Se was lower in asthmatic (1.07 ± 0.12 μmol/L) than in non-asthmatic subjects (1.16 ± 0.31; P = 0.036), Using multiple linear regression, asthma was an independent predictor of decreased platelet GSH-Px after gender, age and serum Se were taken into account (P = 0.048) while atopy was a significant predictor of low whole blood GSH-Px independent of asthma, gender, age and whole blood Se (P = 0.033). Conclusions In addition to Se status, atopy, gender and uge all appear to influence GSH-Px activity, although the relative importance of these factors may difler in asthmatic and non-asthmatic populations. It seems likely that the reduced activity of this enzyme in platelets und hiood may reflect mechanisms associated with the pathogenesis and severity of asthma.     

Comparison of high and low doses of suxamethonium

In a double-blind study, 67 young adult patients undergoing anaesthesia for dental extractions were allocated at random to receive either 0.5 mg/kg or 1.5 mg/kg suxamethonium. A greater increase in arterial pressure was seen following induction in the 1.5 mg/kg group, although overall intubating conditions were similar in the two groups. Suxamethonium-associated muscle pains were significantly more common in the group which received the larger dose (p less than 0.05).     

The epidemiology of irritable bowel syndrome in a random population: prevalence,incidence, natural history and risk factors

Abstract. Objectives . The aim of the study was to assess prevalence, incidence, recovery, and risk factors of irritable bowel syndrome according to different definitions in a large random population. Design . A 5 year follow-up study of a sex- and age-stratified random sample of 4581 Danes interviewed about abdominal symptoms. Setting . The Glostrup Populations Studies Unit at Glostrup County Hospital. Main outcome measures . Prevalence, incidence, recovery, and the association of risk factors to irritable bowel syndrome (IBS). The percentage of subjects common to the populations selected by the various definitions of IBS. Results . According to various definitions, the prevalence of IBS varied from 5 to 65% and the incidence varied from 1 to 36%. At the 5 year follow-up only 5% of subjects with IBS were completely free of all symptoms. Psychological vulnerability and the experience of having problems were strongly associated with prevalence and incidence of IBS, whereas lifestyle factors only showed a very weak or no relationship to IBS. Populations defined as suffering from IBS according to the various definitions had less than 50% of the subjects in common. Conclusions . Irritable bowel syndrome is frequent but fluctuating in the general population. Psychological factors seem to be of greater aetiological importance to IBS than lifestyle factors. However, a generally accepted and precise definition is essential to make future studies comparable and to allow general conclusions to be drawn. Furthermore, it still needs to be verified whether the syndrome is a disease entity or just an acceptable, common life-condition.     

Modification of Late Potentials by Intracoronary Ethanol Infusion

Antiarrhythmic drugs have no consistent effects on the signal-averaged electrocardiogram (ECG) while successful surgical ablation of ventricular tachycardia is known to abolish late potentials. Ten patients with prior myocardial infarction had successful ablation of recurrent sustained ventricular tachycardia by selective ethanol infusion into a small coronary vessel supplying the tachycardia origin. Signal-averaged ECGs were performed before and after initially successful ablation in patients without pacemaker dependence or infra-ventricular conduction delay to assess the effects on late potentials and to determine if the signal-averaged EGG could predict ventricular tachycardia recurrence. Only four of ten patients were eligible for study and all four had late potentials prior to ethanol ablation. Late potentials were abolished in one patient who has not had an arrhythmia recurrence in 25 months. One patient with sudden death and another patient with ventricular tachycardia recurrence had persistent late potentials post procedure that were modified by a reduction in terminal voltage and lengthening of terminal low amplitude signal. The fourth patient who receives chronic amiodarone had no arrhythmia recurrence in spite of persistent but modified late potentials. Thus, the abolition of late potentials after ethanol ablation may predict freedom from arrhythmia recurrence.     

Streptococcus suis infection in Hong Kong

Twenty-five patients were admitted to two hospitals in HongKong for Streptococcus suis infection between 1984 and 1993.Among them, 15 (60%) had an occupational exposure to pigs orpork, and four had a clear history of skin injury up to 16 daysbefore admission. Examination of the cerebrospinal fluid of21 patients confirmed the presence of meningitis in every case;the remaining four patients who did not have lumbar punctureshad each presented with arthritis, bronchopneumonia, endocarditisand pyrexia without neck stiffness. The only fatality was apatient admitted in septicaemic shock with evidence of meningitisand disseminated intravascular coagulation. Of the 24 survivors,16 (67%) acquired varying degrees of hearing loss as a resultof meningitic involvement. All the isolates of S. suis weresensitive to penicillin or ampicillin, which was used aloneor in combination with other antibiotics for every patient.Two patients had a relapse of symptoms when penicillin was stopped,but were successfully treated after the antibiotic was resumedfor a total of 6 weeks. Over 100 cases of S. suis infectionhave been described previously, with a geographic distributionheavily biased towards Northern Europe and Southeast Asia. Lackof awareness of this unique zoonosis may be a reason why itis not diagnosed more readily elsewhere.     

Pagetoid Reticulosis

Two patients with solitary lesions of pagetoid reticulosis are presented. A third case with disseminated lesions and similar microscopic detail is also reported. Lighg microscopic findings include an abnornal cell infiltrate confined to the epidermis and distributed diffusely in a pagetoid pattern. In ultrathin sections, the abnormal cells are seen to have an abundant cytoplasm with numerous organelles and a convoluted nucleus, often with a prominent nucleolus. The nature of the abnormal cells is discussed. The infiltrate is differentiated from that of mycosis fungoides.