A New Method for Easy Demonstration of Argyrophil Cells

A new method for silver impregnation of endocrine cells of the gastrointestinal mucosa is described. It offers great reliability, eveness of impregnation, and, since it can be used on batches of slides, is also suitable for histology class and investigation material. The procedure for paraffin sections of formalin-fixed material is as follows: dewax and transfer to distilled water, leave in 0.5% silver nitrate solution for 2 hours at 60 C. Rinse in distilled water, then treat in Bodian developer (hydroquinone, 1 g; sodium sulphite, 5 g; distilled water, 100 ml) previously heated to 60 C. Rinse in running tap water, distilled water, and then re-impregnate for 10 minutes at 60 C in the same silver solution and reduoc in Bodian's solution. Sma the background is not impregnated by this method, sections may be counterstained by any basic anilin dye to bring out nuclei. A 0.1% kernechtrot solution was found very satisfactory in this respect. The granulations of argyrophil cells stand out sharply black against a red background.     

Distribution and remobilization of symbiotically fixed nitrogen in soybean (Glycine max)

Partitioning of nitrogen by soybeans ( Glycine max L. Merr. cv. Hodgson) grown in natural conditions was studied by successive exposures of root systems to ¹⁵N₂ and periodical measurements of ¹⁵N distribution. Nitrogen derived from the atmosphere was mainly found in the aerial parts of the plants, and the stage of development exerted a strong influence on the initial ¹⁵N distribution (measured one week after incorporation). Until day 69 after sowing, leaf blades contained 47 to 57% of the fixed N. After that, reproductive structures attracted increasing proportions, 10 to 60% between days 69 and 92. Around day 82, stems and petioles stored up to 30% of the newly fixed N. During pod development and pod filling and until maturity, fixed N was remobilized from vegetative tissues and pod walls to seeds. These transfers first concerned the newly incorporated N, but at maturity 80 to 90% of the total was recovered in the seeds. The high mobility of N originating from the atmosphere as compared to that coming from the soil (vegetative tissues exported only 50% of their total N) seems to indicate that fixed N was at least partially integrated in a special pool. This was certainly the case at the later stage of N₂ fixation, when a large portion of fixed N accumulated in the stems and petioles, probably in the form of storage compounds such as ureides for later transfer to the developing seeds. Further research is needed in order to investigate the nature and role of this pool in the nitrogen nutrition of soybeans.     

Metabolic and hormonal parameters after insulin-induced hypoglycemia in man, comparison between biosynthetic human insulin and purified pork insulin

Although clinically undistinguishable, some authors have found important differences in the counterregulatory response between Biosynthetic Human Insulin (BHI) and Purified Pork Insulin (PPI). To reassess the problem 10 healthy volunteers of both sexes underwent paired iv insulin tolerance test with both BHI and PPI (0.10 U/kg b.w.). To check the humoral response the variations of glucose, free fatty acids (FFA), prolactin, growth hormone, ACTH and plasma renin activity were evaluated. Blood glucose depression and further recovery by BHI and PPI administration paralleled each other, so were, prolactin, FFA, and plasma renin activity. A slight section of ACTH, and GH was observed under BHI challenge. There were not statistically significant differences between both insulins on any of the six parameters studied. The data do not confirm earlier published reports indicating hormonal and metabolic differences between human and porcine insulin.     

The substrate specificity of the enzyme amyloglucosidase towards a pentadeoxy derivative of maltose

2,6-Dideoxy-4-O-(2,3-dideoxy-α-d-erythro-hexopyranosyl)-1,5-anhydro-d-arabino-hexitol (2) has been synthesized and characterized by¹H-and¹³C-NMR spectroscopy. The compound is a substrate for the enzyme amyloglucosidase, AMG (EC.3.2.1.3) and the reaction kinetics have been determined using¹H-NMR spectroscopy. Compound 2 is hydrolysed by AMG with a half time of 139 min compared to 76 min for methyl maltoside (1) under identical reaction conditions.     

SIGNIFICANCE OF ANGIOGRAPHIC ABSENCE OF LEFT ANTERIOR DESCENDING CORONARY ARTERY IN A LEFT VENTRICLE WITH INTACT ANTERIOR WALL

Fifteen patients having total occlusion of the proximal left anterior descending coronary artery were studied. All fifteen had normal left ventricular anterior walls. The electrocardiogram was normal in eight patients; old inferior wall infarction was evident in one; anterior ischemia in five; and left anterior hemiblock in one. Collateral circulation was found in twelve patients (80%). These findings suggest that an angiographically non-visualized left anterior descending (LAD) vessel is patent and bypassable in patients where the anterior ventricular wall is intact, thus representing an additional criterion for aortocoronary bypass surgery.     

Immobilised monomers of human liver arginase.

Human liver arginase (L-arginine amidinohydrolase, EC 3.5.3.1) was immobilised by attachment to nylon with glutaraldehyde as a crosslinking agent. Incubation of the immobilised tetrameric enzyme with EDTA followed by dialysis resulted in the dissociation of the enzyme into inactive matrix-bound and solubilised subunits. Both species recovered enzymatic activity after incubation with Mn2+, and the activity of the reactivated matrix-bound subunits was nearly 25% of that shown by the enzyme initially attached to the support in the tetrameric form. When the reactivated bound subunits were incubated with soluble subunits in the presence of Mn2+, they 'picked-up' from the solution an amount of protein and enzymatic activity almost identical to that initially lost by the immobilised tetramer after the dissociating treatment with EDTA. This occurred only in the presence of Mn2+. It is suggested that the reactivation of the subunits of arginase involves the initial formation of an active monomer, which then acquires a conformation that favours a reassociation to the tetrameric state.     

Influence of NaCl in the irrigation water on yield and quality of sweet pepper (Capsicum annuum)

Summary A field experiment was designed to determine the salt tolerance of three varieties of sweet pepper for paprika, studying the effects of four increasing levels of sodium chloride in the irrigation water (5, 10, 29 and 42 meq/l) on soil salinity, yields, and quality of the fruits. EC_5:1 and the soluble sodium and chloride contents increased with increasing salinity. The yields were reduced by 5 per cent for variety ‘Ramillete’, 19 per cent for ‘Tres cascos’, and 40 per cent for ‘Bola’ at the highest level. The fruit quality variables studied (colour index and chloride contents) differed with the variety. re]19750925     

Legionella pneumophila associated with the protozoan Hartmannella vermiformis in a model multi-species biofilm has reduced susceptibility to disinfectants

Legionella pneumophila will infect biofilm-associated protozoa, and in this way might be protected from disinfectants in potable water systems. A base biofilm containing Pseudomonas aeruginosa, Klebsiella pneumoniae, and Flavobacterium spp. was grown on steel coupons in potable water prior to the addition of L. pneumophila and the protozoan H. vermiformis. After 7 d, coupons were removed and treated with 0.5 mgl(-1) free residual chlorine (FRC) or 0.5 mgl(-1) monochloramine (MCA) for 15, 60, or 180 min or 24 h. In a second experiment, only L. pneumophila and the base biofilm organisms were present but with an identical treatment protocol. Treatment of L. pneumophila for 180 min in a system without H. vermiformis resulted in log reductions of 2.07 and 2.11 for FRC and MCA, respectively. When H. vermiformis was present, however, the treatment resulted in log reductions of 0.67 and 0.81 for FRC and MCA, respectively. A similar pattern was observed for 15 and 60 min contact times. These results indicate that L. pneumophila was less susceptible to MCA or FRC when associated with biofilm-associated H. vermiformis in a model potable water biofilm.     

Regulation of the hetero-octameric ATP phosphoribosyl transferase complex from Thermotoga maritima by a tRNA synthetase-like subunit

The molecular structure of the ATP phosphoribosyl transferase from the hyperthermophile Thermotoga maritima is composed of a 220 kDa hetero-octameric complex comprising four catalytic subunits (HisGS) and four regulatory subunits (HisZ). Steady-state kinetics indicate that only the complete octameric complex is active and non-competitively inhibited by the pathway product histidine. The rationale for these findings is provided by the crystal structure revealing a total of eight histidine binding sites that are located within each of the four HisGS-HisZ subunit interfaces formed by the ATP phosphoribosyl transferase complex. While the structure of the catalytic HisGS subunit is related to the catalytic domain of another family of (HisGL)2 ATP phosphoribosyl transferases that is functional in the absence of additional regulatory subunits, the structure of the regulatory HisZ subunit is distantly related to class II aminoacyl-tRNA synthetases. However, neither the mode of the oligomeric subunit arrangement nor the type of histidine binding pockets is found in these structural relatives. Common ancestry of the regulatory HisZ subunit and class II aminoacyl-tRNA synthetase may reflect the balanced need of regulated amounts of a cognate amino acid (histidine) in the translation apparatus, ultimately linking amino acid biosynthesis and protein biosynthesis in terms of function, structure and evolution.