Lipid composition of the peripheral nerves in malnutrition: an experimental study in young rhesus monkeys

An experimental model of protein calorie malnutrition (PCM) was created in young rhesus monkeys. Ulnar and tibial nerves from six monkeys with PCM, six rehabilitated and 12 control monkeys were studied for lipid composition and activity of myelin marker enzyme. Total lipids, myelin marker lipids and activity of myelin marker enzyme, 2', 3'-cyclic nucleotide 3' - phosphohydrolase were decreased, while esterified cholesterol and free fatty acids were increased in PCM as compared to controls. There was partial recovery in myelin marker lipids and complete restoration of other lipids on nutritional rehabilitation.     

Phosphate uptake and involvement of binding protein in Tween-80 supplemented culture ofAspergillus fumigatus

Tween-80 supplementation in submerged culture ofAspergillus fumigatus resulted in an increase of phosphate uptake. The uptake system was characterized as saturable, energy-dependent and operating against the concentration gradient. Control and Tween 80 cultures showed similarK _m values for phosphate uptake (50 μm). Cold osmotic shock treatment of the cultures was found to cause considerable reduction in the ability to take up phosphorus with concomitant release of the binding protein into the shock fluid. Binding protein preparation from Tween-80 supplemented cells showed more activity than that from control cells.     

Effect of drought on proteins and isoenzymes in rice during germination

Two drought tolerant varieties TKM-1 and TKM-2 and two drought susceptible varieties Jaya and Improved Sabarmati of rice were studied for soluble protein pattern and isoenzymes of malate dehydrogenase, glutamate dehydrogenase, esterase and peroxidase during germination at different water stress. MDH, GDH and esterase patterns were not affected, but the soluble proteins were changed. Peroxidase isoenzyme pattern from drought tolerant and susceptible varieties showed characteristic differences. The intensity of bands with higher electrophoretic mobility decreased in Jaya and Improved Sabarmati while in TKM-1 and TKM-2 the intensity of these bands did not change much after 72 hr water stress. In shoots of Jaya and Improved Sabarmati, the activity of the peroxidase isoenzymes decreased more than in TKM-1 and TKM-2 shoots with increase in water stress.     

Periodic operation of immobilized live cell bioreactor for the production of candicidin

A lumped model for cell growth and secondary metabolite production in an immobilized live cell bioreactor has been developed. This model is applied here to simulate the performance of an immobilized bioreactor under steady-state conditions and under conditions of periodically varying concentration of a growth-limiting substrate. The results of the simulation study were experimentally verified in the case of the production of the antibiotic candicidin by Streptomyces griseus in an immobilized bioreactor with forced periodic operation. The results of the studies suggest that periodically operated immobilized live cell bioreactors can provide a potent alternative for the production of non-growth-associated biochemicals, as compared to free cell fermentations, pulsed fermentations with process cycle regeneration, and nonregenerated bioreactors. This work has demonstrated that by frequent pulsing of the growth limiting nutrient, stable extended production can be obtained at high specific cellular productivities.     

Incorporation of the gene for a cell-cell channel protein into transformed cells leads to normalization of growth

Summary Incorporation of the gene for connexin 43, a cell-cell channel protein of gap junction, into the genome of communication-deficient transformed mouse 10T1/2 cells restored junctional communication and inhibited growth. Growth was slowed, saturation density reduced and focus formation suppressed, and these effects were contingent on overexpression of the exogenous gene and the consequent enhancement of communication. In coculture with normal cells the growth of the connexin overexpressors was completely arrested, as these cells established strong communication with the normal ones. Thus, in culture by themselves or in coculture, the connexin overexpressor cells grew like normal cells. These results demonstrate that the cell-cell channel is instrumental in growth control; they are the expected behavior if the channel transmits cytoplasmic growth-regulatory signals.     

Haemagglutinin production by enterotoxigenic strains of Clostridium perfringens type A

Thirty-nine enterotoxigenic cultures of Clostridium perfringens type A were studied for enterotoxin and haemagglutinin production. Enterotoxin was quantitated by sandwich ELISA and DOT-ELISA techniques and haemagglutinin titres were determined using sheep and human erythrocytes. Haemagglutinins from only six cultures reacted against both sheep and human erythrocytes; a further 13 reacted only against human erythrocytes, and another five only against sheep cells.The authors are with the Department of Veterinary Public Health and Epidemiology, Ranchi Veterinary College, Birsa Agricultural University, Ranchi-834007 (Bihar), India.     

The alpha 1-adrenergic photoaffinity probe [125I]arylazidoprazosin binds to a specific peptide of P-glycoprotein in multidrug-resistant cells

Much evidence suggests that P-glycoprotein (P-gp) confers multidrug-resistance (MDR) in tumor cells by energy-dependent efflux of hydrophobic cytotoxic agents. In this study, we have used the alpha 1-adrenergic photoaffinity probe, [125I]arylazidoprazosin ([125I]AAP), and identified P-gp as a specific acceptor for prazosin. Drugs to which MDR cells are resistant, including vincristine, vinblastine, doxorubicin, actinomycin D and colchicine as well as agents reversing MDR, including verapamil, nicardipine, prenylamine, diltiazem, trifluoperazine, dibucaine, reserpine, monensin, and progesterone, differentially reduced [125I]AAP photolabeling of P-gp. We also analyzed the influence of alpha 2-adrenergic drugs and dopaminergic drugs on [125I]AAP photolabeling of P-gp. Limited proteolysis of [125I]AAP photolabeled P-gp with Staphylococcus aureus V8 protease revealed that prazosin binds to a single 8 kDa fragment of P-gp.     

Nuclear interactions of retinoic acid-binding protein in chemically induced mammary adenocarcinoma.

Cellular retinoic acid-binding protein (CRABP) was detected in the nuclear fraction of N-methyl-N-nitrosourea-induced mammary cancers after the incubation of cytosol containing [3H]retinoic acid (RA)-bound CRABP with isolated nuclei. CRABP extracted from the nuclei in buffer containing 0.4 M-KCl sedimented as a 2 S component when subjected to sucrose-density-gradient analysis. [3H]RA-CRABP was found to be a prerequisite for the detection of nuclear binding, since the incubation of isolated nuclei or 0.4 M-KCl extract of the nuclei with [3H]RA did not result in any significant binding. Incubation of [3H]RA-CRABP at 25 or 30 degrees C before incubation with the nuclei neither altered the sedimentation coefficient nor enhanced the nuclear binding compared with 0 degrees C incubation. The tumour nuclei contained a saturable number of binding sites with a dissociation constant of 1.6 x 10(-9) M. These results indicate that the action of retinoic acid in the target organ may be mediated by its interaction with the nuclei.