Sensitivity of B- and C-DNA forms to modifications by O-methylhydroxylamine

Effects of high concentrations of lithium, cesium and ammonium chlorides on the reaction ability of free CMP and cytosine in free DNA of CD phage with respect to O-methylhydroxylamine (OMHA) are studied. CMP reaction in all the cases takes place mainly for 24 hours. Like classical B-form, native DNA, having C-form in high ionic strength solution (as estimated from circular dichroism data), is not modificated. Thus, the access of some cytosine residues in intraphage DNA to OMHA is due not to the decreased DNA hydratation in situ, but to the presence of differently ordered regions in DNA.     

Time of day of taking immunosuppressive agents after renal transplantation: a possible influence on graft survival

Large-amplitude circadian rhythms in immune responses and the known variations in the effects of glucocorticoids with the time of day of administration suggest that immunosuppressive regimens may need to take this variable into account. In two similar groups of patients with renal transplants functioning satisfactorily after three months subsequent graft failure developed in 66% of those taking all immunosuppressives in the evening, compared with only 22% of those taking immunosuppressives twice daily (p < 0.05). A survey of other transplant units showed that one unit with outstanding results--graft survival at three years 82%--had a unique policy of morning-only administration of immunosuppressives. Doctors need to consider more carefully the time of drug administration when prescribing, as it may be possible to obtain better results with less toxicity.     

Response of calcitonin cells, parathyroid glands and bone to prolonged calcitonin administration in the Indian palm squirrel, Funambulus pennanti (Wroughton)

The administration of calcitonin (4 MRC units injected intraperitoneally daily for 42 days) caused hypocalcaemia, hypophosphataemia and a decrease in the serum acid phosphatase level in adult Indian palm squirrels, Funambulus pennanti. Hypocalcaemia and the decrease in the serum acid phosphatase level persisted up to 21 days but the hypophosphataemic effect continued throughout the experiment. The serum calcium level increased from day 28 up to day 35 and the serum acid phosphatase level reached the control level at 28 days. At the close of the experiment (42 days), both serum calcium and acid phosphatase levels were again decreased. Calcitonin-induced hypocalcaemia resulted in hypertrophy of calcitonin cells which were densely packed with secretory granules up to day 21 of the treatment. Thereafter they displayed both hypertrophy and hyperplasia till the end of the experiment. Some calcitonin cells showed degranulation after 35 and 42 days of treatment. Few lead-haematoxylin-positive calcitonin cells with collapsed membranes and pyknotic nuclei were also seen in the lumina of the thyroid follicles toweards the close of the experiment. Parathyroid chief cells showed hypertrophy from 21 to 35 days of the treatment. From day 28 to the close of the experiment they released their secretory product. After 42 days of experimental treatment a growth-promoting effect of calcitonin was observed (increase in body weight and femur weight.     

Purification of glutamine transaminase K/cysteine conjugate beta-lyase from rat renal cytosol based on hydrophobic interaction HPLC and gel permeation FPLC

Cysteine conjugate beta-lyase (beta-lyase, EC 4.4.1.13) was purified to homogeneity from rat renal cytosol using a new and highly efficient method, based on C3-hydrophobic interaction (HI) high-performance liquid chromatography (HPLC) in combination with gel permeation fast protein liquid chromatography. The purity of the enzyme was judged from SDS-PAGE and C18-reversed-phase HPLC. The beta-lyase was estimated to be a homodimer consisting of a 47,400-Da subunit with absorption maxima at 280 and 420-430 nm. The specific activity of the purified beta-lyase toward S-(1,2-dichlorovinyl)-L-cysteine (1,2-DCVC) in the presence of alpha-keto-gamma-methiolbutyric acid (KMB) was 6.4 mumol/min/mg protein, which is by far the highest value so far reported. Kinetic analysis of 1,2-DCVC metabolism by the enzyme in the presence of KMB gave Km and Vmax values of 0.33 mM and 8.4 mumol/min/mg protein, respectively. No significant activity of the purified enzyme was detectable with S-2-benzothiazolyl-L-cysteine up to 2 mM. The purified enzyme also had glutamine transaminase K activity (EC 2.6.1.64) as assayed with phenylalanine and KMB as substrates. This specific activity was 16.0 mumol/min/mg. Amino acid analysis of the purified beta-lyase was carried out and was found to be closely similar to the amino acid composition of five other pyridoxal phosphate (PLP)-containing amino acid amino-transferases. This suggests that glutamine transaminase K/cysteine conjugate beta-lyase is a typical member of the PLP-containing aminotransferase group.