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A Torrecilla

Publications and source records attributed to A Torrecilla.

10 recordsLinked to original sources
PubMed2001

Metabolic fate of AMP, IMP, GMP and XMP in the cytosol of rat brain: an experimental and theoretical analysis.

A systematic study of the metabolic fate of AMP, IMP, GMP and XMP (NMP) in the presence of cytosol from rat brain is here presented; the kinetics of both disappearance of NMP, and appearance of their degradation products was followed by HPLC. In the absence of ATP, AMP was preferentially degraded to adenosine with concomitant appearance of inosine and hypoxanthine. In the presence of ATP, AMP was preferentially degraded via IMP. The nucleosides generated in the course of the reactions are further degraded, almost exclusively, via nucleoside phosphorylase using as cofactor the P(i) generated in the reaction mixture. In order to quantify the effect of each one of the enzymes involved in the degradation of NMP, two complementary approaches were followed: (i) the V:(max) and K:(m) values of the enzymes acting in the intermediate steps of the reactions were determined; (ii) these data were introduced into differential equations describing the concentration of the nucleotides and their degradation products as a function of the time of incubation. Factors affecting kinetic parameters of the equation velocity as a function of ATP concentration were introduced when required. The differential equations were solved with the help of Mathematica 3.0. The theoretical method can be used to simulate situations not feasible to be carried out, such as to measure the influence of nM-microM concentrations of ATP on the metabolism of AMP.

5'-Nucleotidase↗
PubMed1995

Labeled adenosine(5')tetraphospho(5')adenosine (Ap4A) and adenosine(5')tetraphospho(5')nucleoside (Ap4N). Synthesis with firefly luciferase.

Labeled dinucleoside polyphosphates are not commercially available, in spite of being important molecules in metabolic regulation. Firefly luciferase (EC 1.13.12.7) is a useful enzyme for the synthesis of adenosine(5')tetraphospho(5')adenosine (Ap4A). As luciferase behaves as a nucleotidase at low ATP concentration, adequate concentrations (higher than 0.1 mM ATP) should be used to obtain a good yield of labeled Ap4A. [32P]Ap4A has also been synthesized from ATP and [32P]PPi. In a first step, [beta, gamma-32P]ATP is generated in a ATP-[32P]PPi exchange reaction catalyzed by luciferase. In a second step, the reaction is supplemented with pyrophosphatase and 32P labeled Ap4A is obtained. Radioactive adenosine(5')tetraphospho(5')nucleoside (Ap4N) can also be synthesized from ATP gamma S and labeled NTP or from low concentrations of labeled ATP and high concentrations of cold NTP. The syntheses of radioactive ApnA and pnA (n > 4) can also be approached with luciferase.

Adenosine Triphosphate↗
PubMed1994

Uric acid synthesis by rat liver supernatants from purine bases, nucleosides and nucleotides. Effect of allopurinol.

The synthesis of uric acid from purine bases, nucleosides and nucleotides has been measured in reaction mixtures containing rat liver supernatant and each one of the following compounds at 1 mM concentration (except xanthine, 0.5 mM and guanosine and guanine, 0.1 mM). The rates of the reaction, expressed as nanomoles of uric acid synthesized g-1 of wet liver min-1 were: ATP, 10; ADP, 37; AMP, 62; adenosine, 108; adenine 6; adenylosuccinate, 9; IMP 32; inosine, 112; hypoxanthine, 50; GTP, 19; GDP, 19; GMP, 27; guanosine, 34; guanine, 72; XMP, 10; xanthosine, 24; xanthine, 144. These figures divided by 55 correspond to nanomoles of uric acid synthesized min-1 per mg-1 of protein. The rate of synthesis of uric acid obtained with each one of those compounds at 0.1 and 0.05 mM concentrations was also determined. ATP (1 mM) strongly inhibited uric acid synthesis from 0.05 mM AMP (91 per cent) and from 0.05 mM ADP (88 per cent), but not from adenosine. CTP or UTP (1 mM) also inhibited (by more than 90 per cent) the synthesis of uric acid from 0.05 mM AMP. Xanthine oxidase was inhibited by concentrations of hypoxanthine higher than 0.012 mM. The results favour the view that the level of uric acid in plasma may be an index of the energetic state of the organism. Allopurinol, besides inhibiting uric acid synthesis, reduced the rate of degradation of AMP. The ability of crude extracts to catabolize purine nucleotides to uric acid is an important factor to be considered when some enzymes related to purine nucleotide metabolism, particularly CTP synthase, are measured in crude liver extracts.

Allopurinol↗
PubMed1994

[Intraabdominal desmoid tumor associated with Gardner's syndrome].

An intra-abdominal desmoid tumour included in Gardner's syndrome is described. Some aspects of this unusual tumour are reviewed, emphasizing the value of CT to evaluate shape, location, size and relation with adjacent structures and therefore to decide the therapeutic plan, to avoid the need for exploratory laparotomies which are, moreover, so inadvisable in these patients. Although the, treatment of choice is surgery, it must be performed in accordance with CT findings. When surgery is not possible is incomplete or after recurrences, alternative methods are recommended.

Adult↗
PubMed1993

[Retroperitoneal hibernoma].

We report a new case of retroperitoneal hibernoma. Hibernoma is a rare, benign soft tissue tumor whose constituent cells resemble those of brown fat tissue, which is present in human fetus and newborn infant and it gradually diminishes in quantity throughout adult life. Retroperitoneal location is unusual. Differential diagnosis with the liposarcoma (the most frequent tumour on this location) is based on the high vascularity of the hibernoma. Total resection of the tumour can achieve complete cure without recurrence nor metastasis.

Aged↗
PubMed1993

[Standard formulas of parenteral nutrition. A study of their use in a general hospital].

The goal of the study was to evaluate the use of parenteral nutrition formulas with standardized g. of nitrogen, carbohydrates and lipids, and to analyze whether the nutritional requirements of the patients treated in our hospital were covered by said formulas or whether it was necessary to change and/or standardize a new formula. To do so, a review was made of 5.646 parental nutrition mixtures prepared in the Pharmacy Service and patterned by the Nutrition Service from April, 1991, to May, 1992, for 308 adult patients. The distribution of the mixtures by services, diagnoses and the frequency of the different standard formulas were studied, comparing standard formula frequency with that of non-standard formulas. Findings showed that 41.9% of nutrition mixtures were patterned in surgery, and the most common diagnosis, cancer, appeared in 24%. Of the mixtures, 67.6% were preestablished formulas, and 32.4% were non-standard formulas. The order of frequency among standard formulas was: basic standard formulas, stress formulas, initial formulas, peripheral formulas, hemodialysis formulas and low-volume formulas. All covered the nutritional needs of a large share of the patients for the different pathologies in which they were indicated. Nevertheless the question of designing a new formula to cover a greater number of situations was raised. Protocolization should take place rationally, to meet the hospital's most frequent pathologies, and effectiveness should be evaluated after tracking and checking each patient.

Adult↗
PubMed1979

Induction of tyrosine aminotransferase in galactosamine hepatitis.

We have induced acute hepatitis in rats with the amino sugar Galactosamine by i.p. injection. The development of the disease was controlled by measurements of several metabolites and enzymes in serum, and light and electronic microscopy. Tyrosine transaminase was induced by i.p. injection of Cortisol, that increases ten times enzyme activity in liver parenchyma of normal rats. This inductive phenomenon cannot be observed in animals with galactosamine hepatitis. We discuss the probable mechanism and their relationship with some forms of viral hepatitis in human beings.

Animals↗
PubMedDate not supplied

[Liver transplantation in pediatrics. Nutritional measures].

Malnutrition is a constant in candidates for liver transplant. Because of their particular characteristics, pre-operative nutritional intervention is difficult to apply, so that post-transplant action is necessary. A retrospective study was made, reviewing the clinical records of all the children undergoing liver transplants in 1992 in the "La Paz" Children's Hospital, while they were in the Pediatric Intensive Care Unit. Two groups of patients were established--A and B--respectively of 15 and 7 children, according to whether or not they had received immediate post-transplant TPN. In Group A, a total of 150 days was evaluated, with TPN (x = 10 +/- 8.3). The amino acid solutions used were for liver insufficiency (48.8%), Kidney insufficiency (33.3%) and standard (17.8%). Lipids were administered on 6.3% of days in four patients' nutrition. In 54.5% of interventions, infectious complications occurred due to immune-suppression. Comparison of the two patient groups show significant results: those in Group A had a 3.2 relative risk of suffering infection (certainty interval 1.3-1.8). In terms of time in the ICU, the Group A patients were admitted for an average of 13.4 days (range 2-37) as opposed to the 6.28 days of Group B (range 3-15). Results were significant, with p < 0.05. In terms of evolution, the survival rate in patients receiving TPN was 86.6% against 71.4% in those receiving enteral nutritional (n.s.). Our results show a high rate of survival (86.6%). It is not possible to conclude the extent to which the introduction of TPN influenced post-operative evolution, as there was no consistency in terms of the patients' clinical situation.

Child↗