Antitoxic immunity against the so-called lung toxin produced by Escherichia coli.

Cross neutralization test with antisera to crude haemolysins produced by some Escherichia coli strains indicated that there were no antigenic differences among the haemolysins tested. These crude preparates showed definite cytotoxicity which could also be cross neutralized by "antihaemolysin" sera. Neutralization experiments were performed in mouse lung test with homologous and heterologous anti-haemolysin sera, and with O and OK sera to the wild type strain and its toxic R mutant. The results showed that the immunity in the mouse lung model is antitoxic and antibacterial.     

An altered heart-labile enterotoxin (LT') produced by Escherichia coli serogroup O55 strain.

An Escherichia coli serogroup O55 strain produced heat-labile enterotoxin only, which exerted unusual effects on cell cultures; it caused elongation of CHO and HeLa cells but no changes in Y-1 cells. Injection of this substance, designated LT', into mouse foot pad and rabbit skin caused a well-expressed necrotic effect beside the LT-like activity. LT' showed no cytotoxic effect and failed to produce mouse lung oedema. The strain was not haemolytic. According to Sephadex G-100 fractionation, the LT' had a high molecular weight. The LT' and the necrotic activities could not be separated by fractionation. Neutralization experiments suggested an antigenic relationship between LT and LT'. The antigenic deficiency of LT' was closely related to the common antigenic component of LT and choleragen. The necrotic effect caused by crude LT' was neutralized only by the homologous serum.     

Experimental studies on the mechanism of the nitroglycerin effect.

The regional decrease of the speed and extent of the contraction and the relaxation of the canine myocardium induced by coronary ligation was enhanced by intravenously administered nitroglycerin (GTN), simultaneously with the decrease of the left ventricular pressure, while the increase of myocardial fiber length caused by that procedure was partly abolished. The above changes could be reproduced by GTN applied directly onto the ischaemic myocardial surface even before the decrease of the left ventricular pressure. These changes induced by GTN might play a role in the decrease or abolishment of regional asynergic wall motion.     

Analysis of biochemical genetic data on Jewish populations: II. Results and interpretations of heterogeneity indices and distance measures with respect to standards.

A nonparametric statistical methodology is used for the analysis of biochemical frequency data observed on a series of nine Jewish and six non-Jewish populations. Two categories of statistics are used: heterogeneity indices and various distance measures with respect to a standard. The latter are more discriminating in exploiting historical, geographical and culturally relevant information. A number of partial orderings and distance relationships among the populations are determined. Our concern in this study is to analyze similarities and differences among the Jewish populations, in terms of the gene frequency distributions for a number of genetic markers. Typical questions discussed are as follows: These Jewish populations differ in certain morphological and anthropometric traits. Are there corresponding differences in biochemical genetic constitution? How can we assess the extent of heterogeneity between and within groupings? Which class of markers (blood typings or protein loci) discriminates better among the separate populations? The results are quite surprising. For example, we found the Ashkenazi, Sephardi and Iraqi Jewish populations to be consistently close in genetic constitution and distant from all the other populations, namely the Yemenite and Cochin Jews, the Arabs, and the non-Jewish German and Russian populations. We found the Polish Jewish community the most heterogeneous among all Jewish populations. The blood loci discriminate better than the protein loci. A number of possible interpretations and hypotheses for these and other results are offered. The method devised for this analysis should prove useful in studying similarities and differences for other groups of populations for which substantial biochemical polymorphic data are available.     

46,XX/46,XX,del (10) (p13)/47,XX,+r/47,XX,del (10) (p13), + r mosaicism and partial trisomy 10p phenotype (author's transl)]

The mosaicism 46,XX/46,XX,del(10)(p13)/47,XX, +r/47,XX,del(10)(p13), +r was found in the lymphocytes and the fibroblasts of a patient with the following : profound mental retardation; craniofacial dysmorphism with frontal bossing, fine eyebrows, a large hypoplastic nasal bridge, prognathism of the upper jaw, thick lips; a long and thin neck; congenital heart disease; skeletal malformations, with club feet; and hypotonia and lax ligaments. These malformations, compatible with the trisomy 10p syndrome, suggest that the supernumerary ring chromosome was composed of 10p material. An increase of HK1 and GOT1 activities was found. This is in favour of a partial trisomy of chromosome 10. The relative frequencies of the clones constituting the mosaic vary from tissue to tissue and with time.     

Intravenous perfusion of adrenaline and adaptation to muscular exercise in man]

Eleven normal subjects underwent epinephrine perfusions (1.9; 6.1; 11.8 ng/min) during a short (20 min) and mild (50% VO2 max) exercise. VO2 was not modified by epinephrine perfusion, while heart rate ventrilation and plasmatic lactate were increased proportionally to epinephrine doses.     

Interaction between gamma-carboxyglutamic acid and glutamate dehydrogenase

The amino acid γ-carboxyglutamic acid, recently discovered in some vitamin K-dependent blood-clotting factors, shows interesting kinetic effects on glutamate dehydrogenase. It is not metabolized by the enzyme; it is a powerful competitive inhibitor (K_i = 3.8 × 10^?4 m) with respect to NAD⁺ and glutamate. On the other hand the reverse reaction is activated by γ-carboxyglutamate, both K_m and V being altered; this effect is additive with the well-known activating effect of ADP.     

The membrane valve: A consequence of asymmetrical inhibition of membrane carriers. I. Equilibrating transport systems

Facilitated membrane transport systems act as valves, or rectifiers, when the substrate affinities on the two sides of the membrane differ substantially, i.e. when the system is strongly asymmetric. The asymmetry may be intrinsic or imposed by a reversible competitive inhibitor acting on only one side of the membrane. Under non-equilibrium conditions such systems allow net movements of substrate to proceed faster, sometimes much faster, in one direction than the other, though the final equilibrium is unaffected. Obligatory exchange systems may also function as valves when inhibited unsymmetrically, permitting exchange to occur more rapidly with one distribution of substrates than with the reversed distribution. Here, unequal flux rates do not depend on unequal concentrations of the substrate on either side of the membrane, but may also occur with equal concentrations, provided the affinities of the two substrates differ.The kinetic theory leading to these conclusions is given here, and it is shown how individual parameters of a carrier system affect the efficiency, or tightness, of the valve. In addition, simple kinetic tests for the operation of a valve are outlined. Examples are cited of transport systems having inhibitor-binding sites on only one surface of the cell membrane, which could function normally as valves. Systems implicated are glucose transport in various cells, the ADP-ATP exchanger of mitochondria, the anion transporter of erythrocytes, and the Na⁺-K⁺ pump.     

Polyploidy and aspartate-transcarbamylase activity in Hippocrepis comosa L.

The DNA content of plants which were sampled in natural di-, tetra- and hexaploid populations of Hippocrepis comosa L. was estimated and the aspartate transcarbamylase activities of the corresponding cell-free extracts were compared. The amount of DNA is not exactly proportional to the number of genomes. The three kinds of populations do not differ in their aspartate transcarbamylase specific activity. While the enzyme properties are identical in the extracts derived from the diploid and hexaploid plants, the aspartate transcarbamylase present in the tetraploid cytotype shows a slightly lower affinity for one of its substrates and a significantly lower sensitivity to the feedback inhibitor UTP which is still observed after partial purification. These properties might be related to the previously reported greater ability of the tetraploid cytotype to adapt to a variety of biotopes.Abbreviations ATCase aspartate transcarbamylase - CAP carbamylphosphate - EDTA ethylenediaminetetracetic acid - Tris trihydroxymethylaminomethane - AMP adenosine monophosphate - ATP adenosine triphosphate - CMP cytidine monophosphate - CTP cytidine triphosphate - UMP uridine monophosphate - UTP uridine triphosphate     

Effects of nitrogen deficiency and light of high intensity onCryptomonas rufescens (Cryptophyceae)

Summary C.rufescens excystment, experimentally induced, corresponds to a general metabolism recovery of the cell, previously in a resting phase. The cytoplasm changes without any polarity, and organelles like gullet and flagella redifferentiate. The thylakoids develop mainly from the stored lipidic compounds which then disappear. Phycoerythrin immediately fills the intrathylakoidal lumen. Pigment synthesis seems closely associated with the development of membranes. The activated cell divides and the cyst wall breaks down. The destruction of the wall begins in the median layer and is followed by a mechanical rupture of the external and internal layers. Each germinative cyst releases two or four fully differentiated cells. There is an exact symmetry between excystment and encystment, all the transformations of theC. rufescens cell being reversible.