Showing papers by "Catholic University of the Sacred Heart published in 1978"

Glutathione Efflux from Perfused Rat Liver after Phenobarbital Treatment, during Drug Oxidations, and in Selenium Deficiency

Abstract: 1 The efflux of reduced (GSH) and oxidized (GSSG) glutathione from perfused rat liver was studied in different metabolic conditions. 2 At 37 °C in non-recirculating hemoglobin-free perfusion, efflux of glutathione per gram of liver was 14 nmol/min, of which GSH was 12 nmol/min and GSSG 1 nmol/min. Similar rates were observed in livers from phenobarbital-pretreated rats. This is interpreted to indicate that the increased capacity for H2O2 production described in the literature for isolated microsomal membranes is not detectably realized in the intact cell, since H2O2 production from other intracellular sources, e.g. benzylamine, leads to an extra GSSG efflux. Similarly, the glutathione release from livers of selenium-deficient rats low in GSH peroxidase (8% of the selenium-supplemented controls, H2O2 as substrate) was not significantly different from the controls. This observation contrasts with that of Burk et al. [J. Biol. Chem. 253, 43–46] who found a 2-fold increase in glutathione release in livers from rats exposed to selenium-deficiency for a more extended time period. Thus, elevated rates of lipid peroxidation may occur in more severe selenium-deficiency where factors other than a low GSH peroxidase activity may contribute to the effect. 3 An increased rate of GSSG efflux was observed in livers from phenobarbital-pretreated rats during drug oxidations dependent on cytochrome P-450, using aminopyrine, ethylmorphine and hexobarbital as substrates. Half-maximal aminopyrine concentration for GSSG efflux, 0.1–0.2 mM, was similar to that of the extra O2 uptake but lower than that for aminopyrine N-demethylation, 0.5–0.6 mM. Aminopyrine-dependent GSSG efflux was present also in livers from selenium-deficient rats whereas H2O2-dependent or benzylamine-dependent GSSG efflux was abolished. These results do not support extra production of free H2O2 during drug oxidation in the intact cell. Future investigations must evaluate whether glutathione oxidation occurs by reactive drug metabolites or by an enhanced rate of lipid peroxidation, or by back-equilibration of glutathione reductase concomitant with the decreased NADPH levels.

Insulin receptors during the menstrual cycle in normal women.

Abstract: Specific binding of 125I-insulin to circulating monocytes from eight normal menstruating women, four postmenopausal women and four men were studied four times during a 28-day period (one sample at 7-day intervals). Data indicate the presence of a higher specific cell binding fraction in the follicular phase compared to the luteal phase due to changes in insulin receptor concentration. No changes were observed in men or postmenopausal women during the same period of time suggesting that sex hormones should be included among the factors influencing insulin receptors.

Brain stem neurons projecting to neocortex: A HRP study in the cat

Abstract: The cortical projections of the brain stem were investigated in detail in the cat by means of the horseradish peroxidase (HRP) retrograde axonal transport Most of the cells providing ascending fibers to the neocortex were located in the pons (locus coeruleus and related structures, central gray substance, dorsal tegmental nucleus, raphe nuclei, reticular nuclei); labeled neurons were also identified in the mesencephalon, mainly in the periaqueductal gray and in the nucleus linearis rostralis These projections, and particularly the pontine fibers, were diffusely distributed throughout the cerebral cortex

Do presynaptic auto-receptors control dopamine release?

Abstract: MANY studies have attempted the elucidation of the homeostatic mechanisms controlling the amount of neurotransmitter released in the synapse. There is convincing evidence that the release of noradrenaline (NA), from both peripheral and central presynaptic nerve endings, can be modulated by a negative feedback mechanism, whereby the neurotransmitter present in excess in the synapse depresses its further release by activating specific presynaptic α-receptors, α-Agonist drugs interact similarly to NA with these receptors and inhibit the depolarisation-induced release of the amine, whereas α-antagonists counteract this inhibitory effect1–10. The appealing concept of a feedback control of neurotransmitter release, although unequivocally demonstrated only for NA, has been generalised to other transmitters. This generalisation seems rather premature. In particular, the existence of presynaptic autoreceptors controlling dopamine (DA) release is often accepted2,7,11,12; however, recent observations13,14 argue against this interpretation and, as pointed out by Langer15, the presence of a direct control of DA release by presynaptic receptors remains an open question. In our studies on DA release described here, our experimental approach differs in two main aspects from those used previously13,14. First, we have monitored the release of 3H-DA synthesised from 3H-tyrosine, in addition to that of exogenous 3H-DA previously taken up by the nerve terminals. Newly synthesised DA is preferentially released by depolarising stimuli16 and may therefore be preferentially influenced by a feedback mechanism. Second, we have used superfused synaptosomes. In our conditions17,18, the DA released is immediately removed from the nerve endings and any autoinhibition of release is minimised. Therefore, presynaptic receptors are completely available to the agonists (which should decrease the depolarisation-induced release) or the antagonists added to the superfusion fluid. Our results show that the DA agonists have no effect on the stimulus-coupled release of DA, either taken up or newly synthesised, from striatal synaptosomes, and therefore militate against a direct control of DA release through presynaptic autoreceptors similar to that demonstrated for NA.

The specific interaction of s-100 protein with synaptosomal particulate fractions. site-site interactions among s-100 binding sites1

Abstract: — The Scatchard plot of the specific binding of the brain-specific S-100 protein to synaptosomal particulate fractions (SYN) is curvilinear, concave upwards. This could indicate the existence either of multiple classes of sites with different but fixed affinities, or of site-site interactions of the type defined as negative cooperativity among a single class of sites. To discriminate between these possibilities, the dissociation test described by De Meyts et al. (1976) for demonstrating negative cooperativity among insulin binding sites of human lymphocytes or liver membranes, was applied to the interaction of S-100 with SYN. The results show that the dissociation of the 125I-labelled S-100-site complex is faster due to an ‘infinite’(100-fold) dilution of the complex plus an excess of unlabelled S-100 than due to dilution only, the effect of unlabelled S-100 being specific and dose-dependent. 125I-IabeIIed S-100 dissociation is time, temperature, and Ca2 +-dependent. The effect of unlabelled S-100 is more evident at a low site occupancy than at a high one, suggesting that at high site occupancies 125I-labelled S-100 binding sites could be already negatively cooperating. It can be reasonably excluded that the effect of unlabelled S-100 is due to inhibition of rebinding of the dissociated tracer. Na+ and K+ stimulate the dissociation even at physiological concentrations. At low pH 125I-labelled S-100 dissociates very little, while at high pH dissociation is greatly stimulated. Finally, the protein denaturating reagent urea accelerates the dissociation even at concentrations as low as 1m. These data suggest that negative cooperativity occurs among S-100 binding sites, but do not exclude other possibilities. Together with previously reported findings, they further support the view that S-100 binds to highly specific sites in nervous membranes.

Studies on the pr toxin of penicillium roqueforti

Abstract: A mycotoxin, confirmed by chemical, physical and spectroscopic data as the PR toxin described by Ru-Dong Wei and coll. (15) has been isolated from culture filtrates of Penicillium roqueforti Thom. Factors affecting the toxin and mycelium production, acute and chronic toxicity in experimental animals and the frequency of toxinogenesis of 21 isolates of P. roqueforti (including a brown mutant) isolated from different materials, foods especially, were also studied. An hypothesis on the absence of PR toxin in cheeses fermented with P. roqueforti is also advanced.

Kinetics of 21-trisomic lymphocytes. I. In vitro response of 21-trisomic lymphocytes to PHA.

Abstract: Data presented here on the quantitative 3H-thymidine incorporation into DNA, after PHA mitogenic stimulation, show that 21-trisomic lymphocytes are low-responders to PHA compared with the normal-diploid ones. Their responsiveness seems to decrease with the donor's age. Autoradiographic studies clearly demonstrate that the fraction of labeled cells at the 72nd h of incubation is significantly smaller in the 21-trisomic lmphocyte population. The comparison of labeling indexes at different times of incubation (24, 48, 72 h) also indicate, in the same population, a slower increment of the portion of DNA-synthesizing cells. Discussing these data in the light of other's observations and recent progress in the knowledge of factors and mechanisms involved in the lymphocyte response to lectin mitogenic stimulus, it is suggested that differential distribution of T- and B- and/or T-cell sub-populations and a retarded cell induction time to proliferate may be two important factors negatively influencing the responsiveness of 21-trisomic lymphocyte population.

Wicksell Effects and Reswitchings of Technique in Capital Theory

Abstract: The difficulties in traditional capital theory, which have recently given rise to the reswitching of technique debate, are traced back to Knut Wicksell’s analysis of capital accumulation and to his discussions with Gustaf Akerman. Some of the later discussions on the “Wicksell effect” are reviewed. It is shown that the separation of price changes from physical changes—which was proposed by David Champernowne and Trevor Swan in a polemical argument with Joan Robinson—is not possible, in general. It is concluded that Wicksell’s original arguments were correct, although incomplete. When “by the last portion of capital is meant an increase in social capital”, then not only is the marginal productivity of capital unrelated to the rate of profit in any predictable way—as Wicksell pointed out; it no longer has any useful role to play.

Glucocorticoid receptors in human fetal lung

Abstract: A specific dexamethasone binding protein of human fetal lung is described. Characterization of the receptor by sucrose density gradient centrifugation showed a sedimentation coefficient of approximatively 7S (low ionic strenght) and 4S (high ionic strength). Competition studies showed high specificity for glucocorticoids since binding of radioactive dexamethasone was inhibited by Cortisol and corticosterone but not by testosterone and 17/3-estradiol. Uptake of radioactive steroid by isolated lung nuclei required the presence of cytosol and was temperature dependent. The KCI-extractable nuclear complex sedimented at approximatively 5S. Thus the dexamethasone binding components of the human fetal lung have properties similar to those described for steroid receptors present in target tissues. The concentration of receptor remained fairly constant between 15 and 28 weeks of gestation.

Immunoglobulin M specific for measles in serum and cerebrospinal fluid of patients with multiple sclerosis and other neurological diseases.

Abstract: Serum and cerebrospinal fluid of patients with multiple sclerosis, subacute sclerosing panencephalitis and other neurological diseases have been tested by the indirect fluorescent antibody method for immunoglobulin M specific for measles. Only sera of three patients were positive. This feature is of little statistical importance. Nevertheless the authors emphasize the role of a possible viral infection in the pathogenesis of multiple sclerosis.

Intermittent intrathecal methotrexate and fractional radiation (M-IMFRA) plus chemotherapy in childhood leukemia.

Abstract: Preliminary results of our investigation concern 28 consecutive cases of children with acute lymphoblastic leukemia (ALL), treated between March 1974 and March 1978 at the Clinica Pediatrica of the...

Neural discharge of medial geniculate body units and single semicircular canal stimulation.

Abstract: In curarized guinea pigs, 68 neurons of the medical geniculate body (MGB) were tested with vestibular and acoustic stimulations. Single semicircular canals were stimulated thermally. Convergence of acoustic and vestibular afferences on the same MGB unit was observed. Following stimulation of the semicircular canals, activation and inhibition of urinary discharge were recorded, inhibition being predominant, while, when clicks were delivered, bursts of activity occurred. The implications of MGB in vestibular and acoustic integration are postulated.

A study on the possible occurrence of base-exchange reactions in vivo.

Abstract: In mammalian brain, phosphatidylethanolamines and phosphatidyicholines are synthesized from ethanolamine and choline through the intermediate formation of phosphoryl- and CDP-derivatives (1–3). This pathway, also called net synthesis or Kennedy’s pathway, is well known to occur both in vitro and in vivo.

Peripheral vascular dynamics studied by calcium ion inhibition.

Abstract: The study of peripheral vasomotility through inhibition of parietal smooth muscle cells is of great clinical interest for both diagnostic and therapeutic reasons. It permits the differentiation of the functional clinical forms from the organic. And in organic forms, once any spastic component is eliminated, it determines the site and severity. On the basis of these premises we have developed a test for the study of vascular dynamics based on the use of nifedipine as antagonist of calcium ions.

Behavior of a cell line derived from a mouse submaxillary adenocarcinoma during the initial 480 days in vitro.

Abstract: A cell line was established from a transplantable adenocarcinoma, containing viral particles of the A and B type, drived from a tumor appearing spontaneously in the submaxillary region of a male mouse of the C3H/He strain. This line, after 480 days in vitro, did not change the original epithelial-like morphology, the viral expression, the membrane immunofluorescence and the degree of agglutination by various plant lectins. After 208 days of culture, the presence of up to 3 pairs of metacentric chromosomes appeared in about 55% of the cells. However, this change in the chromosomal pattern was not sufficient, at least within the limits of our observation, to modify significantly the other parameters investigated, with the possible exception of the oncogenicity, which showed a modest decrease after 296 days of culture.

Seed quality differences between normal, floury-2 and opaque-2 maize inbreds

Abstract: 142 inbreds of maize (Zea mays L.) and their fl2 and o2 versions, have been compared for seed quality traits. On average, fl2 is superior to the normal and o2 maizes in protein and oil contents and intermediate between normal and o2 in tryptophan content and DBC value. The introduction of the two mutant alleles drastically enhances the variation of the quality traits DBC value and tryptophan content. In association with the higher protein content of the fl2 versions, this effect makes it possible to identify a group of fl2 genotypes with high protein content (14.06%) and high DBC value (65.55), tryptophan content (1.32%) and oil percentage (5.92%).