M Antigens of Group A Streptococci Isolated by Means of Immunochromatography. Biochemical and Serological Properties

M proteins of Streptococcus pyogenes types 1 and 12 were purified by immunochromatography on immobilized type-specific opsonizing antibodies. The M proteins were characterized serologically and biochemically. They absorb after immobilization opsonizing antibodies and only precipitate with homologous antisera in immunodiffusion. In SDS PAGE they show one main band, corresponding to mol. weights of 5 × 10⁴ (type 1) and 5.4 × 10⁴ (type 12), accompanied by faint lines, which form with the main band a precipitation line of identity in SDS-crossed immunoelectrophoresis. Both M proteins aggregate blood platelets and clot fibrinogen.     

Increased lipid peroxidation in malignant tissues of patients with colorectal cancer

The authors investigated the level of lipid peroxidation and possible related phenomena in the activation of phospholipase A2 and the infiltration of granulocyte neutrophils in human colorectal cancer tissue samples. Malondialdehyde (an index of lipid peroxidation), phospholipase A2 activity, and myeloperoxidase activity (a marker of granulocyte neutrophils) were found to be increased significantly in cancerous compared with macroscopically normal tissues. They concluded that increased lipid peroxidation, phospholipase A2, and myeloperoxidase activity are associated with human colorectal cancer.     

Effects of intracoronary nifedipine on blood flow and segment shortening in normal and ischemic myocardium: potentiation by ischemia of the negative inotropic effect

The effects of intracoronary nifedipine on myocardial blood flow (flow probe or microspheres) and regional function (ultrasonic crystals in subendocardium) were examined both in the normal myocardium and in myocardium made ischemic by a partial coronary occlusion in the open-chest anesthetized dog. In a first group of experiments (n = 7), without ischemia, nifedipine infused into the left anterior descending coronary artery (LAD) during a 1-min period (doses 0.75-8 nmol/kg body weight) decreased coronary vascular resistance with a maximal effect at 4 nmol/kg. Systolic segment shortening was decreased from 10.7 to 7.4% (p less than 0.05) by 6 nmol/kg, whereas lower doses had no effect. In a second experimental group (n = 7), a partial LAD occlusion was applied to decrease subendocardial segment shortening by about 50%. Nifedipine (2 nmol/kg) injected into the partially occluded LAD induced a marked segmental bulging during early systole and systolic segment shortening was eliminated (from 4.2 to -3.1%, p less than 0.02) in the LAD-dependent myocardium. Concomitant with the decreased regional function, nifedipine caused a transmural redistribution of myocardial blood flow in the ischemic area, the endocardial/epicardial blood flow ratio increasing from 0.49 to 0.61 (p less than 0.02). It is concluded that ischemia potentiates the direct depressant effect of nifedipine on myocardial regional function.     

Distribution and fate of C14-amitriptyline in mice and rats

Summary The physiological distribution of intramuscularly and intravenously injected C¹⁴-amitriptyline was studied in mice using an autoradiographic technique. The compound rapidly leaves the blood and concentrates in the brain, lung and heart. High concentrations are also seen in the gastric mucosa, intestines, salivary glands and lachrymal glands.The compound is rapidly metabolized in the body. The excretion studies indicate that amitriptyline is excreted to a large extent into the bile as a glucuronide conjugate.The significance of the tissue distribution in relation to the main pharmacological action and to some of the side effects are discussed.The authors are indebted to Professor J. Rieder, Fa. Hoffmann-La Roche & Co., Basel, Switzerland for his helpful suggestions. Thanks are due to Mrs. G. Mabo, Mr. A. Nilsson and Mrs. B. Hagtorn for their valuable technical assistance. The authors are also indebted to Knut and Alice Wallenbergs Stiftelse for general equipment for isotope research work.     

Combined effects of tri-n-butyl tin (TBT) and diuron on marine periphyton communities detected as pollution-induced community tolerance

The effects of combined toxicity were studied, using marine periphyton communities exposed to mixtures of tri-n-butyl tin (TBT) and diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea, DCMU) in indoor aquaria during four weeks. The experimental design of the study followed a central composite design (CCD) and utilized dose-response surface methodology for evaluation of the results. The detection of pollution-induced community tolerance (PICT) was accomplished by short-term (1 h) tests on inhibition of photosynthesis. Both single-toxicant and two-toxicant short-term tests were used. Two tentative measures of tolerance are proposed to achieve convenient comparisons of the tolerances from the two-toxicant tests. With the detection of PICT, effects of the long-term exposure were recorded on diatom species richness, chlorophyll a accumulation and copepod abundance. The decrease of diatom species richness was accompanied by an increased tolerance (PICT), which was detectable by all tolerance measures used. Primary effects on microalgae were recorded as a decrease in chlorophyll a at higher toxicant concentrations. At lower concentrations, primary effects on copepods were found, which resulted in reduced grazing and increased chlorophyll a content.     

Distribution of different fibre types in human skeletal muscles: A statistical and computational model for the study of fibre type grouping and early diagnosis of skeletal muscle fibre denervation and reinnervation

To define fibre type grouping in terms of random and non-random arrangements of the two fibre types, type 1 (ST) and type 2 (FT), we adopted the measure of counting the number of “enclosed fibres”;. The statistical properties of the number of enclosed fibres, and the number and size of groups of enclosed fibres were studied in computer-simulated muscle cross-sections, using a model based upon hexagonal-shaped fibres. The effects on the results of differences in the sizes of the muscle fibres were considered. The applicability of the model, and the derived results and methods of analysis were tested on 10 samples from a cross-section of a whole human muscle. The results show that the model can be applied to various shapes and sizes of muscle samples and various sizes of muscle fibres. The number of enclosed fibres within a muscle sample is the best of the three measures of non-randomness considered. A test is also described for assessing whether or not the observed number of enclosed fibres is random at a given significance level.