Antibody response of inbred mouse strains to ordered tetrapeptides of tyrosine and glutamic acid attached to multichain polyalanine or polyproline. Tyr-Tyr-Glu-Glu is a major determinant of the random poly-(Tyr, Glu)-polyDLAla--polyLys

Five inbred mouse strains which represent high and low responders to the random synthetic polypeptide poly(LTyr,LGlu)-polyDLAla--polyLLys, designated (T, G)-A--L, to which the immune response is controlled by an H-2-linked gene, were immunized with three ordered tetrapeptides composed of tyrosine and glutamic acid attached either to multichain poly-DL-alanine or to polyproline. Only one of the three antigenic determinants, namely tyrosyl-tyrosyl-glytamyl-glutamic acid (T-T-G-G), resembled the random peptide (T, G) in the pattern of immune responses elicited against it, and in the cross-reactivity of the specific antibodies with (T, G)-A--L. The immune response pattern to the other two ordered tetrapeptides, T-G-T-G and G-T-T-G, was different from that obtained with (T, G)-A--L, and no cross-reactivity was detected between the antibodies provoked with these peptides and (T, G)-A--L. Thus, it is suggested that T-T-G-G is a major determinant in the random (T, G)-A--L.

Effects of ethacrynic acid on frog gastric mucosa in chloride solutions

The addition of ethacrynic acid to a concentration of 1 mM in the nutrient solution bathing the frog gastric mucosa in vitro produced an immediate decrease in resistance followed by an increase in resistance and a decrease in H+ secretory rate. The latter effect was irreversible and the former reversible. During the initial phase for nutrient solutions of 4 mM K+ and 79 mM K+ containing 1 mM ethacrynic acid, the decrease in resistance was about 30% and the decrease in the transmembrane potential difference (P.D.) was about 1 mV in the low K+ case and 2 mV in the high K+ case. The addition of ethacrynic acid to a 4 mM K+ nutrient solution containing 1 mM Ba2+ produced initially a 19% decrease in resistance and both positive and negative changes in P.D. In the absence of Ba2+, these results suggest strongly a marked increase of K+ permeability with the possibility of some increase of Cl− permeability. In the presence of Ba2+, as a result due to the increased K+ resistance of the nutrient membrane, ethacrynic acid may affect predominantly either K+ or Cl− permeability.

malB region in Escherichia coli K-12: characterization of new mutations

Phenotypic characterization and mapping of more than 50 Mal(-) mutations located in the malB region lead one to divide the site for Mal(-)lambdas mutations (formerly called gene malB) in that region, into two adjacent genetic segments malJ and malK. malJ and malK are both involved in maltose permeation. It is suggested that (i) malK and lamB, the only known gene specifically involved in phage lambda adsorption (20), constitute an operon of polarity malK lamB. (ii) malJ and malK correspond to two different genes, and (iii) a promoter for the malK lamB operon is located between malJ and malK. Since lambda receptors and maltose permease are inducible by maltose and absent in malT mutants, it is likely that the expression of the malK lamB operon is controlled by the product of gene malT, the positive regulatory gene of the maltose system.

Isolation of the bacteriophage lambda receptor from Escherichia coli

A factor which inactivates the phage lambda can be extracted from Escherichia coli. This factor is a protein and is located in the outer membrane of the bacterial envelope. It is found in extracts of strains which are sensitive to phage lambda, but not in extracts of strains specifically resistant to this phage. We conclude that this factor is the lambda receptor, responsible for the specific adsorption of the phage lambda to E. coli cells. A partial purification of the lambda receptor is described. Inactivation of the phage by purified receptor is shown to be accompanied by the release of deoxyribonucleic acid from the phage.

Late hypoalbuminaemia and albumin metabolism in paraplegic and tetraplegic patients

1. Plasma albumin concentration was decreased in thirty-five of eighty-six mobilized para- or tetra-plegic patients studied months or years after injury to the spinal cord causing a medullary cross-sectional syndrome. The colloid osmotic pressure was low in thirty-one of eighty-one patients in whom it was measured. Plasma volume was normal in thirty and slightly elevated in three of thirty-three patients in whom it was determined. None had oedema at the time of the investigation.

2. Albumin metabolism was studied in ten patients by means of 131I-labelled albumin. Six of these had a decreased plasma albumin concentration. This was probably caused by an increased fractional catabolic rate, although a statistically significant causal relationship could not be demonstrated.

3. in spite of the low plasma albumin concentration normal compensatory mechanisms such as an increase in rate of albumin synthesis and shift of albumin from the extravascular to the intravascular compartment were not found. On the contrary, for unexplained reasons, the average rate of synthesis and the ratio intravascular/total albumin mass were both decreased.

Lithium-induced hyperpolarization of the human rectum in vivo

The transmucosal potential difference across the rectal mucosa was measured in 30 healthy subjects and in 13 psychiatric patients on lithium treatment for manic-depressive psychosis. It was significantly greater in the lithium-treated patients. A highly significant correlation was found between the potential difference and the serum lithium, and in all eight patients in whom it was measured before and one week after starting lithium treatment a rising potential difference was found. This phenomenon may possibly be explained in terms of resistance of the rectal mucosa to vasopressin.