Cooperativity of lectin binding to lymphocytes,and its relevance to mitogenic stimulation

The relationship between the binding patterns of soybean agglutinin, peanut agglutinin (both in their native (unaggregated) form and in their polymerized form), and of Phaseolus vulgaris leucoagglutinin, to neuraminidase-treated lymphocytes from different sources, and the mitogenic activity of these lectins, was studied. In all cases investigated, binding of a lectin to lymphocytes which resulted in stimulation was a positive cooperative process. Our findings support the assumption that clustering of receptors and conformational changes in membrane structure are prerequisites for mitogenic stimulation.     

Hemin feedback inhibition at reticulocyte δ-aminolevulinic acid synthetase and δ-aminolevulinic acid dehydratase

Addition of hemin (5–200 μM) to a rabbit reticulocyte iron-free incubation medium, resulted in a progressive inhibition of heme synthesis as measured by incorporation of (¹⁴C)-glycine. In contrast when (¹⁴C) δ-aminolevulinic acid incorporation into heme was studied, significant inhibition below that of the (¹⁴C)-glycine control only occurred with hemin concentrations greater than 100 μM. Hemin progressively inhibited cellular and mitochondrialδ-aminolevulinic acid synthetase activity, as well as cellular δ-aminolevulinic acid dehydratase activity. The results indicated that elevated levels of hemin initially control heme synthesis by feedback inhibition at the rate-limiting enzyme of heme synthesis, δ-aminolevulinic acid synthetase. Hemin inhibition of δ-aminolevulinic acid dehydratase is only significant for the entrire heme synthetic pathway when greater than one-third of this enzyme's activity is inhibited.     

Reactions of 3-(1-arylhydrazono-L-threo-2,3,4-trihydroxybutyl)-1-methyl-2-Quinoxalinones

The 1-methyl derivatives (3 and 4) of 3-(1-phenyl- (1) and 3-(1-p-bromophenylhydrazono-L-threo-2,3,4-trihydroxybutyl)-2-quinoxalinone (2) were prepared by methylation. Periodate oxidation of 3 gave 1-methyl-3-[1-(phenylhydrazono)glyoxal-1-yl]-2-quinoxalinone (5), which, on reduction with sodium borohydride, gave the corresponding 3-[2-hydroxy-1-(phenylhydrazono)ethyl] derivative (8). Reaction of 5 with hydroxylamine or benzoylhydrazine gave the corresponding 2-oxime (6) and 2-(benzoylhydrazone) (7), respectively. Acetic anhydride causes one molecule of 3 or 4 to undergo elimination of two molecules of water, with simultaneous acetylation and ring closure to afford pyrazoles 9 and 10, respectively. Pyrolysis of the triacetate of 3 led to the elimination of acetic acid from the sugar and the hydrazone residue, to give the 3-[5-(acetoxymethyl)-1-phenylpyrazol-3-yl] derivatives (9). Acetic acid was found to effect the same rearrangement, but without acetylation, of 1, 2, and 3 to give the 3-[5-(hydroxymethyl)] derivatives 11, 12, and 13, respectively. The structure of these pyrazoles was confirmed by a series of reactions, including methylation and acetylation. The n.m.r. and i.r. spectra of the compounds were investigated.     

Phenolic synthesis in Perilla cell suspension cultures

Suspension cultures of Perilla ocymoides accumulate caffeic acid, both in free and ester forms, as the only phenylpropanoid end metabolite. Increased levels of growth substances influenced the levels of PAL activity and phenolic accumulation so that cytokinin stimulated, while auxin repressed both parameters. The regulatory role of caffeyl compounds is discussed in relation to their accumulation during the early exponential phase of culture growth.     

Anthropological studies among Libyans. Erythrocyte genetic factors,serum haptoglobin phenotypes and anthropometry

Anthropological studies were done on 1276 Libyans from the Mediterranean cities of Tripoli and Benghazi, and from Sabha southward in The Sahara. The incidences of hemoglobin (Hb)-S and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency were low in the coastal areas and significantly high in Sabha. Hb-C occurred sporadically in Tripoli and Sabha, and was absent from Benghazi in the east. One case of Hb-J Benghazi was noted. There were no significant differences in the ABO blood group and Rh₀ (D) type distributions in the three localities. G-6-PD gene Gd^A frequency was significantly high in Sabha. The lowest value of 6-phosphogluconate dehydrogenase (6-PGD) gene PGD^A frequency and highest value of the gene PGD^C were in Sabha. Adenylate kinase (AK) gene AK² was only detectable in Tripoli. Acid phosphatase (AP) gene P^a frequency in Sabha was more than twice that in Tripoli and Benghazi, while P^c was distinctly lower in Sabha than in the northern cities. Haptoglobin gene Hp¹ frequency was almost identical in all areas. Anthropometric measurements revealed overall homogeneity of the three samples, closer similarity in the coastal region to adjacent North African populations, and Negroid influence in the Saharan Libyans. Anthropometry substantiated findings from blood markers.     

Some observations on the fine structure of the mantis shrimp heart

Summary The electron microscopic structure of the myocardium of the mantis shrimp is descriped. Particular attention is paid to the organization of the nerve terminal and the sarcotubular system. The general appearance of this myocardium is characterized by deep invagination of the plasma membrane at the level of Z-band and large irregular shaped mitochondria. It possesses a very well developed sarcotubular system, consisting of the longitudinal system and two transverse elements making two sets of contact to each other. One forms dyad and the other forms triad at the level of M- and Z-band, respectively. The organization of the myoneural junction in this muscle is very simple and undifferentiated. In general, a special structural differentiation is invariably observed at both sides of the contact area. In spite of the fact that synaptic vesicles and a differentiated membrane are found at the naked process of this cardiac nerve, specialization such as subsynaptic fold formation has not been observed at the muscle side which is in contact with the nerve process. Observations made on the sarcotubular system and the nerve termination have been discussed with reference to their physiological significance. This investigation was supported by the Public Health Service Research Grants HE 06968-04 and NB 03348-04 of the National Institutes of Health, Bethesda, and the U. S. Department of the Army through its Far East Research Office.     

Studies on the antibacterial effects of negapillin in combination with other antibiotics and sulfa drugs

Summary The antibacterial effect of negapillin in combination with other antibiotics and sulfa drugs was studied using Gram+ve and Gram-ve bacteria as test organisms. Subsequently, various proportions of negapillin in combination with the antibiotics and the sulfa drugs were examined to determine the optimum proportions which exert maximum inhibitory effects on the bacterial growth. Mixtures of these antibiotics with negapillin were found more superior not only as antimicrobial agents but also for having comparatively low toxicity.