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Biomedical subjects

M Rodríguez

Publications and source records attributed to M Rodríguez.

At least 325 records · Page 18Linked to original sources
PubMed1992

Expression of thyroglobulin gene in maternal and fetal thyroid in rats.

The relationship between the changes in thyroglobulin (Tg) mRNA and Tg proteins during thyroid development in the fetus and in maternal thyroid glands during gestation and lactation is studied. While the appearance of Tg mRNA (fetal day 15) showed good temporal correlation with that of 12S Tg, no 19S Tg could be detected until 3 days later. The 12S Tg was the predominant protein on days 18 and 19 of gestation in the fetus, while 19S Tg was the predominant protein on fetal days 21-22 and during the postnatal period in the offspring; by the 20th postnatal day, the 19S Tg content per gland was 4 times the amount of 12S (155 vs. 37 micrograms/gland; P less than 0.001). The 19S iodine content in the fetus was the same as that in 12S up to the 21st day of gestation, except for lower values on day 18. From fetal day 22 and through the postnatal period, the iodine content in 19S was 1.6-5.9 times greater than that in 12S. Therefore, the ratio of atoms of iodine per mol Tg during the experimental period changed from 0.75 to 19.5 for 19S and from 0.72 to 7.2 for 12S. The levels of all of the iodoamino acids were low on fetal days 17-19, after which they increased at different rates for each protein. The greatest increase in monoiodotyrosine and T3 corresponded to 12S, while diiodotyrosine and especially T4 showed a greater increase in 19S than in 12S Tg; 20 days after birth, the T4 content in 19S was about 3 times greater than that in 12S Tg. The soluble thyroid proteins from pregnant, lactating, and nonpregnant female controls contained a main protein, 19S, and a smaller amount of 27S. Both 19S Tg and 19S iodine contents were already lower than those in nonpregnant rats at 14 days of pregnancy, and the levels continued to decrease during the experimental period. In contrast, the 27S Tg and 27S iodine levels remained constant and similar to nonpregnant values. Surprisingly, a decrease in the level of Tg mRNA was observed during pregnancy and lactation. We have no explanation for the dramatic decrease in Tg mRNA during the last days of pregnancy. Further studies should help to elucidate the mechanism responsible for the changes in Tg gene expression in the thyroids of pregnant and lactating rats.

Animals↗
PubMed1992

[The prevalence of HCV antibodies in 3 groups with distinct patterns of sexual activity].

We studied the prevalence of antibodies to hepatitis C virus (anti-HCV) among 164 heterosexual partners of anti-HCV-positive subjects, 131 prostitutes and 52 homosexual men. 6.7% of heterosexual monogamous partners had anti-HCV; the seropositivity rate was associated with a long-term sexual practice and with age. Of the 131 prostitutes, 6 (4.6%) had anti-HCV; there were significant associations in patients positive for anti-HCV, with a history of parenteral drug addiction. 11.5% of homosexual men were anti-HCV positive; there were significant associations with positivity for antibodies to HIV, intravenous drug abuse and with the number of sexual partners. We concluded that the HCV may be transmitted by sexual route, but the high seroprevalence among prostitutes and homosexuals may be explained by other parenteral mechanisms.

Age Factors↗
PubMed1992

[A study of some pathogenic factors of Salmonella typhi].

30 strains isolated from clinical cases and a laboratory induced R-mutant or S typhi were studied. The synthesis of Colicin V, Siderophores, hydroxamate and phenolate (Aerobactin and Enterochelin) were investigated using biological assays. All strains were positive for Enterochelin but only strains 6586 and 4448 were positive for Aerobactin. An 80 kD receptor for enterochelin was found in the outer membrane of strains. Only strains 4448, 635 and 4693 produced Colicin V. Plasmid related antibiotic resistance was demonstrated in 7 strains and was considered "cryptic" in 3 others. The LD50 for mice ranged from 2.7 x 10(4) to 1 x 10(9) bacteria per ml. The presence of pathogenic factors was not related to the LD50.

Colicins↗
PubMed1992

[Microbiology in Chile: development through a century of existence].

Microbiology starts in Chile at the end of the XIXth century as part of the effort to develop basic sciences at the University of Chile Medical School. Publications by Vicente Izquierdo on gonorrheae and Alejandro del Río on the organisms of dysenteriae were pioneer works in this area. The field was progressively developed in the Schools of Medicine, Dentistry, Pharmacy, Veterinary Medicine, Institute of Hygiene and Public Health and different hospitals. Many scientists have been trained in the United States, Canada or Europe. Post graduate training in Chile led to the first Masters degree in 1975 and the first doctoral degree in 1987. Although there is a shortage of well trained scientists and specialists, the field remains active as evidenced by publications, meetings and the existence of 3 specialized journals.

Chile↗
PubMed1992

[Motor fluctuations in Parkinson disease: risk factors].

We studied the histories of 173 patients with Parkinson's disease (1985-1987) chronically treated with levodopa + dopa decarboxylase inhibitor. Ninety four patients had daily motor fluctuations and 79 showed stable motor response. The most significant differences between fluctuating and stable patients were given by age at disease onset and duration of levodopa therapy. Patient with disease onset before 60 had a greater risk (p less than 0.001) of developing fluctuations. Delaying the initiation of levodopa treatment was not associated with a smaller incidence of fluctuations.

Adult↗
PubMed1992

First documented outbreak of dengue in the Peruvian Amazon region.

This article describes a classical dengue outbreak caused by dengue serotypes 1 and 4 that occurred from March to July 1990 in the city of Iquitos and surrounding areas of Loreto Department in the Peruvian Amazon. Epidemiologic data indicate that more than 150,000 persons may have been affected in Iquitos alone. Another dengue outbreak occurred in Tarapoto, a city in the neighboring department of San Martín. Laboratory data indicate that the same dengue serotypes were involved in both outbreaks. No cases of dengue hemorrhagic fever/shock syndrome appear to have occurred. Prior to this outbreak, no indigenous dengue cases had been documented in Peru.

Dengue↗
PubMed1992

[Fluconazole treatment of cryptococcal meningitis associated with HIV infection. Presentation of 4 cases].

We present four cases of C. neoformans meningitis (CNM) in patients with Human Immunodeficiency Virus (HIV) infection treated with fluconazole p.o. at an initial dose of 400 mg followed by 200 mg/day during a follow up period ranging from 3 to 12 months, and who presented an excellent clinical evolution. When comparing them to our previous cases who were treated with Amphotericin-B in combination with 5-fluorocytosine, a decrease in mean hospital stay (p less than 0.001) and a smaller incidence of secondary effects were observed. Treatment with fluconazole seems to be an effective alternative in treatment of CNM. Future greater studies are needed to confirm this findings.

Administration, Oral↗
PubMed1992

[Redistribution of fetal cardiac output in intrauterine growth retardation].

One hundred and thirty-one fetuses with a gestational age between 29 and 41 weeks have been studied by Doppler-Echocardiography. The cases include normal pregnancies and those with a risk for congenital heart disease. We compared the cardiac output distribution, calculated by Pulsed Doppler-Echocardiography, between the intrauterine growth retardation cases and those with normal growth. The normal and relative dominance of the right versus the left ventricle is demonstrated in normal pregnancies and normal growth fetuses. This ratio is clearly inverted in the growth-retarded cases. This redistribution of blood flow may be a response to chronic hypoxia allowing preferential flow of the blood to the brain.

Cardiac Output↗
PubMed1991

[A comparative therapeutic and multicenter trial of rifampicin and doxycycline versus streptomycin and doxycycline in human brucellosis].

BACKGROUND: Comparison and evaluation of the efficacy and safety of two treatment schedules in human brucellosis. METHODS: A comparative, randomized, multicentric, open study of 45 days doxycycline plus rifampin in the initial 21 days (group A) versus 45 doxycycline plus streptomycin in the initial 14 days (group B). 42 were included in each group. The diagnosis of brucellosis was based on blood culture or consistent clinical findings and a Wright's serum agglutination titer of 1/160 or greater. Clinical and laboratory monitoring was carried out, including blood cultures on the days 7 and 48 and after 3, 6, and 12 months. RESULTS: 38 patients in each group were evaluable at the end of treatment. 3 group A patients and 1 group B patient had initial therapeutic failure. 31 group A patients and 35 group B patients could be followed up during 6 months or more (mean follow up of 10.5 and 11.5 months, respectively). 9 relapses (29%) developed in group A and 2 (6%) in group B (p less than 0.05). 22 patients of the 34 finally evaluated in group A (65%) were considered as cured, versus 33 of the 36 in group B (92%) (p less than 0.01). Side effects not requiring withdrawal of the treatment developed in 12 patients, without differences between the two groups. CONCLUSIONS: In the therapy of human brucellosis, the association of doxycycline (45 days) and rifampin (21 days) is less effective than the classical association of doxycycline and streptomycin.

Adolescent↗
PubMed1991

[Cost-effectiveness analysis of home administration versus hospital administration of intravenous immunoglobulin].

A prospective analysis was carried out to evaluate the cost-effectiveness of two alternatives for the treatment of hypo-agammaglobulinemia with intravenous immunoglobulin: the current hospital administration and the administration in the patient's home. 38 patients or relatives were surveyed about their personal or family characteristics, current therapy and the possibility to be treated at home. Home therapy is feasible--43% of the patients would be able to have it and would prefer it--and less costly, as costs could be reduced in 18-20%. This alternative is felt as a greater patient's independence, with less feeling of illness and preventing the loss of school or work hours. 32% prefer the hospital because they feel more secure in it.

Adolescent↗
PubMed1991

In vitro effects of arginine vasotocin on testosterone production by testes of rainbow trout (Oncorhynchus mykiss).

The objective of this study was to investigate the effect of arginine vasotocin (AVT) on testosterone (T2) production by the rainbow trout testis in culture. AVT increased T2 production in a dose-dependent manner in immature testes. The maximum response (10 nM AVT) increased T2 production 6-fold over basal (3-6 pg/mg tissue protein). Mature testes did not respond to AVT. Salmon gonadotropin (2.5 nM sGtH, SGA-GtH) stimulated T2 production by both juvenile (5-fold) and mature (11-fold) testes. When AVT (100 nM) was added in addition to salmon gonadotropin (sGtH; from 0.1 to 100 nM), AVT had a stimulatory effect at the submaximal doses of sGtH, but T2 production did not exceed the maximum level obtained with sGtH (100 nM) alone. Isotocin also increased T2 production although to a lesser degree than AVT. The maximum response at 10 nM increased T2 production 4-fold over basal. beta-Endorphin had no effect on T2 production.

Animals↗
PubMed1991

Effects of maternal stress during pregnancy on forced swimming test behavior of the offspring.

It has been reported that gonadal steroids modulate brain and behavioral sex differentiation during development. Prenatal maternal restraint also alters development by affecting gonadal steroid levels in the fetus. Prenatal maternal restraint of animals decreases sex differences for sexual behavior, locomotion, aggression, etc. In recent work on animal models, we reported that, like humans, laboratory rats show sex differences in depression. From the present study, performed on Sprague-Dawley rats, we conclude that: 1) there are sex differences for depression in two different animal models (swimming-induced immobility and natatory tests); 2) there are also sex differences in open-field behavior; 3) prenatal maternal restraint decreases sex differences for depression but does not affect sex differences in open-field behavior; 4) prenatal maternal restraint affects female but not male behavior in the two depression tests used. These results suggest that: 1) sex differences reported in animal models of depression are under the control of gonadal steroids during prenatal brain development; 2) stress during early phases of development increases the risk for depression in adulthood.

Animals↗
PubMed1991

Design of two immobilized cell catalysts by entrapment on gelatin: internal diffusion aspects.

Experimental results obtained during the design of two immobilized cell catalysts by entrapment on gelatin are presented. Strong diffusional limitations are found and explained with the usual parameters and models, introducing an empirical correlation between substrate concentration and effectiveness factor. The effect of particle size, enzyme load, and specific activity in the system is discussed in terms of cooperation between bioengineers and geneticists.

Catalysis↗
PubMed1991

Interfering with calcium release suppresses I gamma, the "hump" component of intramembranous charge movement in skeletal muscle.

Four manifestations of excitation-contraction (E-C) coupling were derived from measurements in cut skeletal muscle fibers of the frog, voltage clamped in a Vaseline-gap chamber: intramembranous charge movement currents, myoplasmic [Ca2+] transients, flux of calcium release from the sarcoplasmic reticulum (SR), and the intrinsic optical transparency change that accompanies calcium release. In attempts to suppress Ca release by direct effects on the SR, three interventions were applied: (a) a conditioning pulse that causes calcium release and inhibits release in subsequent pulses by Ca-dependent inactivation; (b) a series of brief, large pulses, separated by long intervals (greater than 700 ms), which deplete Ca2+ in the SR; and (c) intracellular application of the release channel blocker ruthenium red. All these reduced calcium release flux. None was expected to affect directly the voltage sensor of the T-tubule; however, all of them reduced or eliminated a component of charge movement current with the following characteristics: (a) delayed onset, peaking 10-20 ms into the pulse; (b) current reversal during the pulse, with an inward phase after the outward peak; and (c) OFF transient of smaller magnitude than the ON, of variable polarity, and sometimes biphasic. When the total charge movement current had a visible hump, the positive phase of the current eliminated by the interventions agreed with the hump in timing and size. The component of charge movement current blocked by the interventions was greater and had a greater inward phase in slack fibers with high [EGTA] inside than in stretched fibers with no EGTA. Its amplitude at -40 mV was on average 0.26 A/F (SEM 0.03) in slack fibers. The waveform of release flux determined from the Ca transients measured simultaneously with the membrane currents had, as described previously (Melzer, W., E. Ríos, and M. F. Schneider. 1984. Biophysical Journal. 45:637-641), an early peak followed by a descent to a steady level during the pulse. The time at which this peak occurred was highly correlated with the time to peak of the current suppressed, occurring on average 6.9 ms later (SEM 0.73 ms). The current suppressed by the above interventions in all cases had a time course similar to the time derivative of the release flux; specifically, the peak of the time derivative of release flux preceded the peak of the current suppressed by 0.7 ms (SEM 0.6 ms). The magnitude of the current blocked was highly correlated with the inhibitory effect of the interventions on Ca2+ release flux.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗