Comparative study of the interactions AMP-phosphorylase b and AMP analogues-phosphorylase b

The different effects induced by AMP and its analogues on the tertiary structure and the coenzyme environment of phosphorylase b were studied by titration of the slowly reacting thiol groups and by quenching of the coenzyme fluorescence, respectively, to determine the possible differences that activate phosphorylase b. The following results were obtained: The coenzyme environment depends upon the nucleotide studied. AMP, when bound to its first site, opens the coenzyme pocket. The slow cysteines were shielded by the nucleotides against their DTNB titration depending on the nucleotide studied. The enzyme difference spectra in presence of the nucleotide showed that the negative band of 260 nm is similar for all nucleotides possessing the same base, but the positive band obtained in the presence of AMP was diminished when other nucleotides were present.     

Effect of short term fasting on plasma composition of lactating rats

The effects of a 24-h fast upon plasma and blood components of the lactating rat on day 20 after parturition have been determined. Body weight decrease observed with fasting was more marked in nursing dams than in controls. The changes observed agree with a limited use of lipidic resources, exhaustion of liver glycogen and considerable utilization of amino acids as energetic - as well as gluconeogenetic - substrates. Blood and plasma glucose were maintained in fasted dams at a level comparable with that of controls. The actual variations observed in the plasma aminogram were limited, showing a remarkable maintenance of the dam's own amino-acid homeostasis.     

Body and organ size and composition during late foetal and postnatal development of rat

Development induced deep anatomical changes and tissue composition alterations in the rat. To determine the extent of these changes, the organ weight and size of 19 and 21 day rat foetuses and of 1, 5, 10, 20 and 30 day old Wistar rat pups have been studied and compared with adults. Different tissues showed varying rates of cell and tissue growth as well as tissue cellularity during development. Tail length is not a good index of skeletal growth. Brain growth was much slower from late intrauterine life to adulthood than most other organs. Skin weight increased more than 3-fold between days 19 and 21 of intrauterine life. Striated muscle proportion to body weight remained practically constant throughout all postnatal life studied.     

Liver- and muscle amino-acid concentrations during the development of domestic fowl

The concentrations of free amino acids in liver, leg muscle and wing muscle of developing domestic fowl chicks were measured and compared with those of adults. Leg and breast muscles showed a remarkably parallel pattern of change in free-amino-acid concentrations during development up to day 5 after hatching, in agreement with their lack of differentiation up to day 5. Liver free-amino-acid concentration pattern with the development were very similar to those of the muscles, in significant difference with Mammals. Adult free tissue amino acids were lower than those of developing chicks. Most changes in amino-acid concentration in chick tissues were observed around hatching, and have been tentatively attributed to changes in diet. Combined amino acids changed very little during the period studied in muscles and liver. Taurine constituted a very big share of total amino acids.     

Evaluation of specific antigen and prostatic acid phosphatase specificity. Study of false values

We assayed prostatic specific antigen (PSA) and prostatic acid phosphatase (PAP) serum levels in 1305 subjects without malignant prostatic pathology by double antibody RIA I125 to evaluate their specificity. When we set a second upper normal limit of 10 ng/ml for PSA and 2.5 ng/ml for PAP there was a significant increase of specificity. There were 2 and 3.7% false positive results in non-prostatic benign pathologies, 1.8 and 7.9% in non-prostatic malignant, 3.5 and 4.7% in non-complicated benign prostatic hypertrophy (BPH) and 3.3% for both in chronic prostatitis. In patients with complicated BPH and acute prostatitis the results were 64.8 and 24% for PSA and 20 and 16% for PAP. In conclusion, PSA is more specific than PAP in patients without acute inflammatory pathology of the prostate; the high rate of false positive values in the latter excludes its usefulness in these patients as diagnostic tumoral markers.