Kinetics of phosphorus uptake by immobilizedChlorella

Summary Alginate-entrappedChlorella demonstrate rapid uptake of phosphorus from synthetic growth medium in batch culture. Rates of phosphorus uptake demonstrated by immobilized algae were found to be much lower than those of non-immobilized cells. Uptake was dependent upon matrix stocking density, cell preculture conditions and cell viability, but not upon cell growth.     

Synthetic studies in the series of polyene macrolide antibiotics. 5. Synthesis of methyl-2,4,6-trideoxy-2,4-di-C-methyl-alpha-L- gluco-hexopyranoside and methyl-2,4,6-trideoxy-2,4-di-C-methyl- alpha-L-manno-hexopyranoside, the stereoisomers of the C33-C38 fragment of amphotericin B

The synthesis of the gluco- and manno-stereoisomers of amphotericin B is described.     

Linked genetic markers of the rabbit κ light chain are not linked to the Tcr β chain genes

In order to investigate linkage, we used serum allotypes of the two rabbit C isotypes and restriction fragment length polymorphisms (RFLPs) of the genes for V , C , and T-cell receptor C . The inheritance of these genetic markers was studied through backcross and F₂ matings. Southern analysis and hybridization of genomic DNA with a C probe detected a 5 kb Pst I fragment linked to expression of the K2bas1 allotype and the presence of the 1b ^bas gene and a 6.6 kb Pst I fragment linked to the expression of the K1b9 allotype, the presence of the 2 ^bas2 gene and lack of expression of the K2bas1 allotype. A V probe detected a 1.3 kb Eco RI fragment linked to the presence of the 1b ^bas gene and expression of the K2bas1 allotype. In contrast, the 9 or 14 kb Eco RI RFLP (C ^a or C ^b) detected with a Tcr chain probe segregated independently from C allotypes and RFLPs. It has previously been found that C and C are also unlinked in man, whereas in the mouse they are linked at a distance of 8 centimorgans.     

Measurement of exchange of trace metals between the body and its surroundings with the use of trace methodology

Application of general tracer theory to the problem of estimating fluxes of tracee between the gastrointestinal tract and the body proper, from observations of the movement of tracer, shows that a number of assumptions must be fulfilled. Two specific sets of assumptions are discussed and, in both cases, measurement of tracer fluxes yields information on the integrated absorption of the tracee.     

Proteolysis of tubulin and microtubule-associated proteins 1 and 2 by calpain I and II. Difference in sensitivity of assembled and disassembled microtubules

Calpain I and II (EC 3.4.22.17) are Ca2+-activated neutral thiol-proteases. Isolated brain tubulin and microtubule-associated proteins were found to be good substrates for proteolytic degradation by brain calpain I and II. The assembly of microtubules was totally inhibited when the calpains were allowed to act on microtubule proteins initially, and a complete disassembly was found after addition of calpain I to assembled microtubules. The high-molecular weight microtubule-associated proteins were degraded within a few minutes following incubation with calpain as shown by SDS-polyacrylamide gel electrophoresis and electron microscopy. When calpain was added to pre-formed microtubules, either in the presence or in the absence of microtubule-associated proteins, the proteolysis was significantly reduced. When tubulin was pre-assembled by taxol, the formation of proteolytic fragments was decreased indicating that assembly alters the availability of tubulin sites for proteolytic cleavage by calpain. Digested tubulin spontaneously formed aberrant polymers. No considerable change of apparent net charge was seen, thus indicating that calpain cleaves off fragments containing neutral amino acid residues and/or that the fragments of tubulin remain associated as an entity with the same charge as native tubulin. The results suggest that the calpains act as irreversible microtubule regulators.     

Correlations of blood selenium with hematological parameters in West German Adults

The serum selenium and the whole blood selenium of 72 healthy persons (47 women, 25 men) was determined. There exist sex specific differences of the whole blood selenium between men (98±19 μg Se/L) and women (89±17 μg Se/L). The serum selenium did not show sex specific differences, but sex specific differences are found if the total amount of extracellular selenium is calculated by correction of the serum selenium with the hematocrit. Women have more extracellular selenium/L whole blood (40±8 μg Se) than men (36±7 μg Se). Men have more intraerythrocyte selenium (cellular selenium=67±14 μg Se) in one L whole blood than women (52±17 μg Se). There exist also sex specific differences if the cellular selenium is calculated/g hemoglobin (men .44 μg Se/g Hb, women .37 μg Se/Hb) or per erythrocyte (men 136.1×10^?19 g Se/Ery, women 113.9×10^?19 g Se/Ery). In the cellular compartment of one L whole blood on the average 1.56 times more selenium is present than in the extracellular compartment. Most of the intraerythrocyte selenium is hemoglobin bound (84%) and utmost 16% glutathione peroxidase associated. An erythrocyte contains about 3500 mol glutathione peroxidase, or, for every 80000 mol hemoglobin one mol glutathione peroxidase. A standard man needs about 2.5 μg selenium/d for the synthesis of the hemoglobin and the erythrocyte. The hematological parameters hemoglobin and the erythrocyte number are correlated with the cellular selenium and the ratio cellular selenium/extracellular selenium. Positive significant correlations are found that are best if a parabolic model is used to interpret the shape of the curves. From the shape of the best correlation lines it can be concluded that selenium may be beneficial for hemoglobin synthesis and erythropoesis. The extracellular selenium may have influence on the volume of the erythrocyte by protecting the outer erythrocyte membrane from lipid peroxidation. A method is reported based on the carbon furnace atomic absorption spectroscopy, which is able to determine without wet digestion selenium in whole blood.     

Effects in rats of iron on lead deprivation

In two fully crossed, two-factor experiments, F1 generation male rats were fed a basal diet supplemented with lead (lead acetate) at 0 or 2 micrograms/g and iron (ferric sulfate) at 50 or 250 micrograms/g (Experiment 1). Supplements in Experiment 2 were lead at 0 or 1 micrograms/g and iron at 50, 250, or 1000 micrograms/g. After 28 or 50 d in Experiment 1, and 35 d in Experiment 2, a relationship between lead and iron was found. Body weight was lower in low-lead than lead-supplemented 28-d-old rats regardless of dietary iron, whereas hematocrit and hemoglobin were lower in low-lead than lead-supplemented rats fed 50 micrograms iron/g diet. A similar finding was obtained with hematocrit and hemoglobin in 35-d-old rats. Dietary lead did not affect rats fed 250 or 1000 micrograms iron/g diet. Also, feeding low dietary lead did not affect 50-d-old rats regardless of dietary iron. Liver and bone concentrations of lead were markedly affected by dietary lead and iron. The concentration of lead in liver and bone was lower in low-lead than lead-supplemented rats. Compared to rats fed 50 micrograms iron/g diet, rats fed 250 micrograms iron/g diet exhibited a decreased lead concentration in liver and bone. This decrease was accentuated by lead supplementation. The findings suggest that lead acted pharmacologically to affect iron metabolism in rats.     

Characterization of the cellulase complex from Cellulomonas grown on bagasse pith

Summary The effect of physico-chemical parameters on the cellulolytic activity of Cellulomonas sp. IIbc grown on sugarcane bagasse pith was investigated, and the optimum ranges for enzyme activity were established. The cellulases were more stable when incubated at the optimum growth temperature (32°C) than under optimum activity conditions (45°C for -glucosidases and 50°C for CMC- and FP-cellulases). The -glucosidases were the thermostability-limiting enzymes of the complex. Two types of endoglucanases could be recognized according to their adsorption properties on bagasse: one weakly-bound and one tightly-bound type, the latter constituting approximately 73% of the extracellular endoglucanases at exponential growth phase. Four forms active on filter paper and three active on CMC were obtained by HPLC separation of the extracellular fraction of the culture at stationary phase.Abbreviations CMC carboxymethylcellulose - FP filter paper     

Altered drug metabolism in parasitic diseases

While the immune system represents the main line of host defence against parasite infections, mixed function oxidase (MFO) systems (Box 1) offer the main line of defence against drugs and other biologically active substances. But, as this review shows, many parasites can exert a profound effect on the host MFO system by altering the microsomal drug-metabolizing enzymes and electron transport carriers such as cytochrome P-450. This can markedly affect the host's ability to metabolize biologically active compounds, often with adverse physiological, pharmacological and toxicological consequences. In mammals, drug metabolism occurs predominantly in the liver, and to a lesser extent in the spleen, lungs, kidneys, intestine and cerebral tissues. Thus those parasites that occupy sites in these tissues - such as amoebae, Fasciola, schistosomes and malaria - tend to be those with greatest effects on the host's ability to metabolize drugs. The effects can modify the host response to substances unrelated to the infection, and to drugs which may be administered under a chemotherapeutic regime.