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Biomedical subjects

F Ruiz

Publications and source records attributed to F Ruiz.

At least 127 records · Page 7Linked to original sources
PubMed1980

Genetic interactions in the control of mitochondrial functions in Paramecium. I. Interactions between nuclear genes.

The genetic and physiological properties of two nuclear mutants of Paramecium tetraurelia affecting mitochondrial properties, and first screened as resistant to tetrazolium (TTC) are described. The mutant TTC64-1R is strongly deficient in cytochrome c and the mutant TTC66pR is partially deficient in cytochrome aa3; both mutants display cyanide insensitive respiration in exponential growth phase. In the double mutant TTC64-1R -- TTC66pR/TTC64-1R -- TTC66pR the deficiency in cytochrome aa3 due to the TTC66pR mutation is suppressed. The mutation TTC64-1R does not suppress cytochrome aa3 deficiencies due to mitochondrial mutations, but does interact with another nuclear mutation, cl1, (compatible only with mitochondria deficient in cytochrome oxidase) in such a way that the double mutant TTC64-1R -- cl1/TTC64-1R -- cl1 displays a normal amount of cytochrome aa3. The possible mechanisms and physiological significance of these suppressive effects are discussed.

Animals↗
PubMed1980

Genetic interactions in the control of mitochondrial function in Paramecium. II. Interactions between nuclear and mitochondrial genomes.

In an attempt to understand the genetic interactions between nuclear and mitochondrial genomes leading to mitochondrial biogenesis, different combinations of known nuclear and mitochondrial mutations have been constructed by microinjection. Eleven different tetrazolium resistant mutant strains, many clearly affecting mitochondrial function, were injected with mitochondria from four different erythromycin resistant mitochondrial mutants. Cases were found in which mutant mitochondria were unable to replicate in tetrazolium resistant mutants. The successful mitochondrial transfers were characterized for growth rate, temperature and cold sensitivity. Several selected combinations were characterised also for cytochrome spectra and cyanide resistance. Many different phenotypes were produced by the interaction of the different nuclear and mitochondrial mutations. These ranged from a positive interaction in which mutant mitochondria were selected by a nuclear mutant in preference to wild-type, through apparent absence of interaction, to negative interaction in which the mitochondrial-nuclear combination was temperature sensitive even though both 'parents' were thermoresistant. The possible molecular basis of these interactions is discussed.

Animals↗
PubMed1979

Age at diagnosis and seasonal variation in the onset of insulin-dependent diabetes in Chile (Southern hemisphere).

The age at diagnosis, sex, and the date of both the diagnosis (month--year) and the onset of symptoms of 525 insulin-depdendent diabetic patients, under 30 years of age at the time of diagnosis, were collected retrospectively from hospital records. The patients came from Chilean cities located in the Central Zone: Santiago (87%) and Temuco--Concepcion (13%). The age at diagnosis showed a bimodal distribution up to 19 years of age, with the main peak at 12 years and another at 6 years. The female peak preceded the male peak by 1 to 2 years. The onset of symptoms showed a seasonal variation, with the highest frequency in winter and the lowest in spring (P less than 0.01). There was also a significant variation in the time of diagnosis, especially in the 0--19 age group: most cases were diagnosed in winter (June, July) with the lowest number in summer (December).

Adolescent↗
PubMed1978

Selection and characterization of nuclear mutations affecting mitochondria in Paramecium.

A screening method, based upon resistance to a tetrazolium salt (TTC), is described which permitted the isolation in Paramecium of 28 mutants resistant to TTC. These mutants displayed various defects in mitochondrial functions (cytochromic content cyanide insensitive respiration). Some mutations seemed to affect directly the respiration chain while others seemed to cause indirect modifications, possibly altering mitochondrial protein synthesis. Genetic analysis of four mutants showed in all that the resistance to TTC was of nuclear origin.

Animals↗
PubMed1978

[Electrolytic and electrocardiographical correlations under 7% oxygen in nitrogen in dogs (author's transl)].

Electrolytic concentrations in plasma and electrocardiographic parameters in dogs have been studied by means of lineal and canonical correlations, after the animals have been submitted to 7% oxygen in nitrogen for three hours. At the end of hypoxia there appeared hypokalemia, increased T wave potential, low R wave and enlargement of ST segment and PQ interval. The coefficients of lineal correlation between Mg++ levels in plasma and R wave potential and those of Na+ and QRS interval were reversed at the final stages of hypoxia.

Animals↗
PubMed1975

Familial chondrocalcinosis in the Chiloe Islands, Chile.

Studies about chondrocalcinosis in the Chiloe Islands (Chile) showed the high frequency of the disease there and how most of it is aggregated in a few highly involved families. Pedigrees and the high degree of consanguinity among parents of index cases pointed to a recessive inheritance. The presence of common Caucasian anthropological features of genetic value in the patients and the lack of Indian mixture in three of the involved families, documented back to 1600, suggest a Caucasian origin of the mutation. Biochemical studies of the patients' synovial fluid showed a significant rise in pyrophosphate concentration. Calcium, phosphorus, and alkaline phosphatase concentrations were not different from a control group.

Adult↗
PubMed1972

Gene dosage dependence of pigment synthesis in melanoma x fibroblast hybrids (hamster cells-mouse fibroblast-DOPA-oxidase-irradiation).

Hybrids between Syrian hamster melanoma cells and mouse fibroblasts, containing one genome (1s) of each parent, produce neither melanin nor DOPA-oxidase ("extinction"). Attempts to induce loss of the fibroblast chromosomes by irradiation of the fibroblasts before fusion with melanoma cells resulted in the formation of colonies comprising pigmented hybrid cells, which contained 2s melanoma and 1s fibroblast chromosome-complements suggesting that extinction or re-expression of melanogenesis is a function of genic balance. This interpretation was confirmed by crosses between 2s melanoma cells with unirradiated 1s fibroblasts, which produced both pigmented and unpigmented hybrids. No correlation has thus far been established between karyotype and phenotype of the hybrid cells, but analysis of the karyological data suggests that the fibroblast chromosomes responsible for extinction cannot be numerous.

Animals↗