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C Roncero

Publications and source records attributed to C Roncero.

46 records · Page 3Linked to original sources
PubMed1988

Effect of calcofluor white on chitin synthases from Saccharomyces cerevisiae.

The growths of Saccharomyces cerevisiae wild-type strain and another strain containing a disrupted structural gene for chitin synthase (chs1::URA3), defective in chitin synthase 1 (Chs1) but showing a new chitin synthase activity (Chs2), were affected by Calcofluor. To be effective, the interaction of Calcofluor with growing cells had to occur at around pH 6. Treatment of growing cells from these strains with the fluorochrome led to an increase in the total levels of Chs1 and Chs2 activities measured on permeabilized cells. During treatment, basal levels (activities expressed in the absence of exogenous proteolytic activation) of Chs1 and Chs2 increased nine- and fourfold, respectively, through a mechanism dependent on protein synthesis, since the effect was abolished by cycloheximide. During alpha-factor treatment, both Chs1 and Chs2 levels increased; however, as opposed to what occurred during the mitotic cell cycle, there was no further increase in Chs1 or Chs2 activities by Calcofluor treatment.

Benzenesulfonates↗
PubMed1988

Isolation and characterization of Saccharomyces cerevisiae mutants resistant to Calcofluor white.

Calcofluor is a fluorochrome that exhibits antifungal activity and a high affinity for yeast cell wall chitin. We isolated Saccharomyces cerevisiae mutants resistant to Calcofluor. The resistance segregated in a Mendelian fashion and behaved as a recessive character in all the mutants analyzed. Five loci were defined by complementation analysis. The abnormally thick septa between mother and daughter cells caused by Calcofluor in wild-type cells were absent in the mutants. The Calcofluor-binding capacity, observed by fluorescence microscopy, in a S. cerevisiae wild-type cells during alpha-factor treatment was also absent in some mutants and reduced in others. Staining of cell walls with wheat germ agglutinin-fluorescein complex indicated that the chitin uniformly distributed over the whole cell wall in vegetative or in alpha-factor-treated cells was almost absent in three of the mutants and reduced in the two others. Cell wall analysis evidenced a five- to ninefold reduction in the amount of chitin in mutants compared with that in the wild-type strain. The total amounts of cell wall mannan and beta-glucan in wild-type and mutant strains were similar; however, the percentage of beta-glucan that remained insoluble after alkali extraction was considerably reduced in mutant cells. The susceptibilities of the mutants and the wild-type strains to a cell wall enzymic lytic complex were rather similar. The in vitro levels of chitin synthase 2 detected in all mutants were similar to that in the wild type. The significance of these results is discussed in connection with the mechanism of chitin synthesis and cell wall morphogenesis in S. cerevisiae.

Benzenesulfonates↗
PubMed1987

Regulation of rat foetal lipogenesis in brown adipose tissue in vivo and in isolated brown adipocytes during the last day of, and after prolonged, gestation.

Rates of lipogenesis in foetal isolated brown adipocytes from 22-day-pregnant rats were significantly increased by lactate plus pyruvate as major substrates in the incubation medium, in comparison with the endogenous rates. Insulin stimulated foetal brown-adipocyte lipogenesis, and adrenaline or noradrenaline and isoprenaline decreased lipogenesis. Glucagon had no effect on the lipogenic rate in brown adipocytes. Progesterone administration to the mother significantly increased the rates of lipogenesis in brown adipose tissue and in isolated brown adipocytes from 22-day foetuses. Prolongation of gestation by progesterone to day 23 decreased the rates of brown-adipose-tissue lipogenesis in vivo and in isolated cells in the post-mature foetuses.

Adipose Tissue, Brown↗
PubMed1986

Adenine nucleotide compartmentation in foetal rat hepatocytes. Effects of atractyloside, oligomycin, calcium ionophore and adrenergic agonists.

In the presence of lactate plus pyruvate, or glucose or alanine as substrates, ATP/ADP ratios in the cytosol were higher than in mitochondria in isolated rat foetal hepatocytes. The cytosolic ATP/ADP ratios were dependent on substrate (lactate + pyruvate greater than glucose greater than alanine). Oleate increased the cytosolic ATP/ADP ratios in the presence of the other substrates studied. Atractyloside decreased the cytosolic ATP/ADP ratios, oligomycin decreasing these values in both compartments. Isoproterenol, phenylephrine and Ca2+ ionophore decreased the cytosolic ATP/ADP ratio, without altering this value in mitochondria.

Adenine Nucleotides↗
PubMed1986

The role of prolactin and progesterone in the regulation of lipogenesis in maternal and foetal rat liver in vivo and in isolated hepatocytes during the last day of gestation.

The administration of progesterone on day 21 of gestation increases the rates of lipogenesis in the liver in vivo and in hepatocytes isolated from rats on day 22 of pregnancy. Bromocriptine administration increases the rates of hepatic lipogenesis in vivo, but has no effect on lipid synthesis in hepatocytes under the same treatment conditions. Concurrently, the administration of progesterone or bromocriptine on day 21 to the mother increases the rates of lipogenesis in the foetal liver in vivo on day 22. The rates of lipid synthesis in foetal isolated hepatocytes are increased by progesterone administration, but remain unchanged by bromocriptine.

Animals↗
PubMed1985

Effect of Calcofluor white and Congo red on fungal cell wall morphogenesis: in vivo activation of chitin polymerization.

Calcofluor White (a fluorochrome dye) affected the growth of Geotrichum lactis by causing lysis of cells at the hyphal tips. This effect was prevented by the presence of an osmotic stabilizer. The growth of Saccharomyces cerevisiae was also affected, and multicellular aggregates were formed because of incomplete separation of mother and daughter cells; fluorescence microscopy indicated the presence of abnormally thick septa. The formation of rudimentary wall material by G. lactis protoplasts was promoted by Calcofluor or Congo red (another dye). The rate of chitin synthesis in protoplasts and growing cells was enhanced by both dyes. In contrast, both dyes inhibited chitin and beta (1,3)-glucan synthases in isolated cell-free systems. Degradation rates for beta (1,3)-glucan or chitin were not affected significantly by the dyes. Wheat germ agglutinin also affected chitin synthesis in protoplasts.

Benzenesulfonates↗
PubMedDate not supplied

[Hyperviscosity syndrome and mental disorders].

The hyperviscosity syndrome has been described clinically as the triad of bleeding, visual signs and neurological manifestations associated with elevated serum viscosity. Several reports have recognised an association between hyperviscosity and altered mental status. Since to our knowledge only a case of hyperviscosity-induced delirium has been described (1), we raise the possibility of this diagnosis in the most of this reported cases, based on the nature of the symptoms, sudden onset and fluctuating course, and its resolution with plasmapheresis. In this paper we review the literature about hyperviscosity syndrome and altered mental status. In conclusion, serum hyperviscosity should be added to the large list of causes altered mental status, especially of delirium. Since plasmapheresis can reverse clinical symptoms, it early recognition and the measurement of serum viscosity is essential in patients suffering from diseases that may lead to this syndrome, and who develop psychiatric symptoms.

Blood Circulation↗
PubMedDate not supplied

[Risperidone in the treatment of psychotic patients with opiate abuse and dependence].

INTRODUCTION: 180 psychotic patients with opiate dependence and abuse (ICD-10) were included in an open label study. The study objectives were to evaluate safety and efficacy of risperidone for a six month follow-up period. The total mean dose was 4.4 (SD: 2.4 mg/daily; range: 0.5-12 mg/daily). METHODS: BPRS, CGI and DDS-SV were used to assess efficacy and UKU subscale for neurological side effects and spontaneous reports for safety. RESULTS: Risperidone treatment improved symptoms, disability of the included patients with a significant reduction in the mean total scores of BPRS, CGI and DDS-SV observed from the first month of treatment onwards. Risperidone also reduced illegal opiate abuse patients from 39% basedate to 18% at month 6. There was a significant reduction (p< 0.0001) in the total UKU subscale for neurological side effects scores from visit 1 onwards for studied sample. Risperidone was well tolerated by the study patients. From 165 elegible patients, just 10 (6.1%) discontinued treatment due to adverse reactions, 94% of the patients did not suffer any adverse event; the most frequent adverse events according spontaneous reports were extrapyramidal effects (3%) and anxiety (1.8%). DISCUSSION: Risperidone improved disability, psychotic symptoms and tolerability of these patients. Those results could mean an outstanding breakthrough in the treatment of these type of disorders and, if it is confirmed that risperidone can lead to abstinence, we would be before a new line of treatment for dual pathology.

Adolescent↗
PubMedDate not supplied

[The dopaminergic system and addictions].

AIM: All psychoactive substances with a high abuse potential are characterized by altering the mesocorticolimbic dopaminergic neurotransmission system. In this article it is proposed to review the neurobiological mechanisms that comprise the foundation of the development of addiction. DEVELOPMENT: The acute drug intake provokes an increase in extracellular dopamine which, in vulnerable individuals, could be the start of the addictive process. Chronic drug use is accompanied by a reduction in the dopaminergic function with the development of neuroadaptive changes in the mesolimbic and mesocortical pathways. In the prefrontal cortex, the changes in dopaminergic function produce an inbalance between receptors D1 and D2, which leads to a predominance of inhibitatory function. Dopaminergic innervation in the amygdala and its interaction with the nucleus accumbens plays an essential role in the conditioning of environmental stimuli, and can trigger the craving and relapse. In drug dependent patients, dopaminergic changes extend from the limbic regions to the associative and sensorimotor striatum, and affect the cortico-striatico-cortical circuits. CONCLUSION: The involvement of the dopaminergic systems is crucial in the development of addiction, from the early phases in which drug use begins as an object-directed instrumental behavior, to the consolidation of the addiction as a compulsive habit, controlled by stimulus-response mechanisms, which progressively invade all aspects of the life of an individual.

Dopamine↗