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Biomedical subjects

M C Rubio

Publications and source records attributed to M C Rubio.

122 records · Page 7Linked to original sources
PubMed1977

Effects of db cAMP on tyrosine hydroxylase activity of ganglia and nerve endings.

Preincubation of intact superior cervical ganglia or nictitating membrane for 2 h with dibutyryl cyclic AMP (db cAMP) increased the hydroxylation of tyrosine. This effect was not blocked by the protein synthesis inhibitor, cycloheximide. The Km of tyrosine hydroxylase for the substrate, tyrosine, and for the cofactor, reduced pteridine, were decreased by db cAMP. There were no changes in the Vmax of the enzyme. The inhibitory potency of noradrenaline on the hydroxylation of tyrosine was also decreased. Thus an inductive effect may be ruled out. The activation of the enzyme was only observed when the tissues were preincubated with the db cAMP and not when the cyclic nucleotide was added to the isolated enzyme. Preincubation of cervical ganglia for 4 h with db cAMP increased activity of decarboxylase and monoamine oxidase in tissue homogenates without changing the tyrosine hydroxylase activity.

Animals↗
PubMedDate not supplied

Robust methods in bioequivalence assay; preliminary results.

The aim of this study is to compare four statistical methods for outlier identification in Bioequivalence tests. The methods are based in four confidence intervals, 'parametric','non- parametric','robust with the asymptotic distribution of the M-estimator' and 'robust with the bootstrap distribution'. The drug we used was Diltiazen, in a two sequence randomized crossover study design. The pharmacokinetic parameters measured were the area under the plasma concentration curve (AUC), and the peak drug concentration (CMAX). Time to peak drug concentration (TMAX), was not used here in order to separate the efficiency of the methods from the efficiency of the measurements. The methods were applied to simulated and experimental data. We made two simulations, one with normal data and another one with outliers data. When simulating normal data all methods showed similar profiles and high power. On the contrary, when simulating experiments with outliers data, the parametric method showed low power, whereas robust methods showed just a slight decrement in power. When we analyzed experimental data of AUC, if we used the parametric method (recommended by U.S.P), we were not able to conclude Bioequivalence, but with the other methods, this was possible. This disagreement between parametric and robust procedures was a sign of outliers data. We conclude that the robust methods in bioequivalence assays help us in the identification of outliers as observations with weight equal zero.

Adult↗
PubMedDate not supplied

Hemodynamic effects on hepatic blood flow of a selective beta 2-adrenoceptor agonist, clenbuterol, in rat.

Acute clenbuterol administration (50 micrograms/kg, i.v.) to anesthetized normotensive rats, produce a marked reduction in the mean blood pressure, (MBP), about 58 mm Hg. Indocyanine Green clearance analysis (control, 1.83 +/- 0.15: clenbuterol, 1.10 +/- 0.20 ml/min/100 g, P < 0.05) showed that the action in the hepatic vascular bed is opposite to its systemic vasodilator effects. The hepatic blood flow (HBF) appears significantly reduced (control, 8.24 +/- 0.35: clenbuterol, 3.83 +/- 0.71 ml/min/100 g, P < 0.05) whereas the hepatic uptake and excretion proceedings were apparently not affected (control hepatic extraction coefficient, 0.225 +/- 0.024: clenbuterol, 0.300 +/- 0.04, NS). These findings show that a marked reduction in HBF follows systemic vasodilator effects produced by clenbuterol.

Animals↗
PubMedDate not supplied

Effects of chronic ethanol feeding on sympathetic innervated organs: temporal sequence of biochemical, functional, and trophic changes.

In noradrenergic nerves as well as in effector organs of the sympathetic nervous system, chronic ethanol feeding induced biochemical, functional, and trophic changes. The time sequence of modifications in the activities of tyrosine hydroxylase, phenylethanolamine-N-methyl transferase, monoamine oxidase, endogenous norepinephrine levels, as well as the neuronal uptake mechanism and secretory responses to norepinephrine in the submaxillary gland of the rat, confirms that the effects of chronic ethanol administration are related to an increase in sympathetic tone.

Adrenal Glands↗
PubMedDate not supplied

[Fungi inside and outside the homes of subjects with immediate hypersensitivity in Zaragosa (Spain)].

In the study of patients with hypersensitivity to atmospheric fungi, the determination of species distribution in the personal environment of the patient is important. This distribution depends on climate variations, especially temperature and percent (%) humidity which favor the development of one or other genera. In the domiciliary surroundings, the technological advances in comfort (wetness, dryness, with refrigeration and heating systems) favor the establishment of a closed ecosystem which can sometimes contain fungi different from that found exteriorly; at times true colonization. Our objective is to compare the incidence of the different groups of intra and extra-domiciliary fungi in our environment (Zaragoza, Spain) and to verify their presence in the domiciles with their exterior surroundings, of 23 atopic patients, of which 8 had clinical asthma and/or rhinitis and demonstrable allergy to fungi, by PRICK and RAST. The other 15 patients were diagnosed as having asthma and/or rhinitis with a positive PRICK and RAST to house dust and Dermatophagoides or pollen allergens (non-allergic to fungi). Five Petri dishes were given to each patient; one dish contained 5 mm. of Agar-Sabourad following Lumpkins' formula, and was used for extra-domiciliary exposure. The rest contained the same medium to which was added a 0.33% solution of Rose Bengal (an inhibitor) for internal exposure. This medium allows the development of a large number of genera of fungi. These 5 dishes were situated and remained in place for 60 minutes; the 4 interior ones were placed in different locations and always included the dormitory and living room.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Microbiology↗