Reciprocal interaction between seasonal testis and thyroid activity in Zembra Island wild rabbits (Oryctolagus cuniculus): effects of castration, thyroidectomy, temperature, and photoperiod.

The reproductive cycle of wild rabbits (Oryctolagus cuniculus) living in Zembra Island (North Tunisia) is dependent on an external factor, the photoperiod: the gonads are inhibited by long days and stimulated by short days or melatonin implants. Here we studied the role of an internal factor, thyroid hormones and the possible thyroid-gonadal interrelationships, in animals captured on Zembra Island and maintained in natural conditions of photoperiod and temperature. We determined the seasonal profile of the thyroid and testis cycles and investigated the effects of castration and thyroidectomy on the seasonal testosterone and thyroxine cycles. Plasma thyroxine and testosterone levels followed similar, parallel seasonal patterns, with a peak in autumn (October) and low values from January to August. In thyroidectomized animals, plasma testosterone levels, although significantly higher than those in controls (P < 0.001), remained low throughout the 13 mo of the experiment, and no testicular reactivation was observed in the fall. In castrated animals, despite the increase in thyroxine concentration in the 3 mo following castration (P < 0.01), plasma thyroxine levels remained low during the 2 yr of the study. We then investigated the combined effects of long days (16L:8D) and moderately high temperature (25 degrees C) on these two endocrine axes. In constant gonado-inhibiting conditions (16L:8D), whether the temperature was kept constantly high or allowed to fluctuate naturally, no reactivation of the thyroid and testicular axes was observed in the fall. In control animals, the peaks of testosterone and thyroxine concentrations observed in September were larger (P < 0.001) than those in animals subjected to the same natural photoperiod conditions but with constantly high temperature. The lower level of autumnal testis stimulation (P < 0.001) in animals maintained in conditions of constant high temperature (25 degrees C) may be attributed to the low thyroxine levels induced by high temperature. These results clearly confirm that the thyroid and testicular cycles display similar seasonal variations and show that the thyroid and gonadal axes are strictly interdependent. This study provides the first demonstration, for a given species, that the seasonal reactivation of gonad activity is controlled by the thyroid, and thyroid activity is controlled by the gonads.

Long-day inhibition of reproduction and circadian photogonadosensitivity in Zembra Island wild rabbits (Oryctolagus cuniculus).

We investigated the effects of photoperiod on testicular activity in wild rabbits (Oryctolagus cuniculus) captured on Zembra Island (North Tunisia) and maintained in experimental photoperiodic conditions. Sexually inactive animals were subjected to alternate 3-mo periods of short days (8L:16D) and long days (16L:8D) for 1 yr. Testicular activity increased significantly and then decreased to levels equivalent to or lower than those measured during sexual quiescence after 1 mo of 8L:16D or 16L:8D, respectively. Eight groups of sexually active animals were also exposed to 8L:16D for 60 days. The light phase was divided into two photofractions (7.5 and 0.5 h). The short photofraction interrupted the dark phase 9.5-18.5 h after the beginning of the main photofraction. Testicular activity was inhibited if the short photofraction interrupted the dark phase 12.5 h or more after the beginning of the main photofraction. These results clearly confirm that photoperiod affects reproduction in this species: Short days stimulate reproduction, whereas long days inhibit it. The asymmetric pattern of skeleton photoperiods used demonstrated the existence of a circadian rhythm for photogonadosensitivity, with the photosensitive phase beginning 12.5 h after dawn. In this species, photoperiod length controls both the beginning and the end of the reproductive period. These results differ from those obtained with continental populations of wild rabbits, in which reproduction is inhibited by short day length. This difference may reflect genetic drift linked to the geographic isolation of this population, which is known to have been present on this small island for more than 2000 yr.

[Incidence and risk factors in fractures of the proximal femur due to osteoporosis]. / Incidencia y factores de riesgo de la fractura de fémur proximal por osteoporosis.

Every year more than one million fractures of the proximal femur occur in the world, especially in older persons. Given the continuous aging experienced by populations, such fractures will become more frequent from year to year and will constitute a growing public health problem. The largest increase is expected to occur in countries of Latin America around the year 2050. Since nearly 70% of all atraumatic fractures in persons over 45 are due to osteoporosis, a case-control study was conducted in the city of Mar del Plata, Argentina, for the purpose of investigating the incidence of and the risk factors associated with proximal femur fractures due to osteoporosis. Between 1 August 1992 and 31 July 1993, a record was kept of all fractures of the proximal femur due to osteoporosis in persons over 50 years of age that visited any of the city's 30 public and private health centers. A total of 246 cases was recorded. The incidence rate per 100,000 inhabitants in the above-50 population was 259 among women and 92 among men, for a ratio of 2.8:1. The incidence was consistently higher in the older age groups, especially in persons over 75. Factors associated with a statistically significant increased risk of fracture of the proximal femur were: a history of neurologic disorders, psychotherapeutic drug use, alcohol consumption, previous fractures, cardiovascular disease, and a decreased intake of milk products. There were no observed differences between cases and controls with respect to age at menopause, weight, height, previous activity, smoking habits, or sun exposure, nor were such differences detected in terms of the percentage of women who had undergone oophorectomy.

Prevalencia de bocio en escolares (6 a 14 años) de la ciudad de Mar del Plata / Goiter prevalence in school children (6 to 14 years) of Mar del Plata city

El objetivo de este trabajo fue determinar la prevalencia de bocio en escolares de la ciudad de Mar del Plata. Se seleccionó una muestra entre alumnos de 6 a 14 años de edad de escuelas urbanas y periurbanas de la ciudad de Mar del Plata; la muestra se realizó por conglomerados y posteriormente por métodos aleatorios. Se encuestaron 889 alumnos, 54,1 por ciento de sexo masculino y 45,9 por ciento del femenino, y se recolectó orina en un 8,7 por ciento de los varones. Se detectó un 17,2 por ciento del nivel Ia, 1,7 por ciento Ib y 0,1 por ciento II Total = 19 por ciento (según clasificación OPS). No se observaron diferencias significativas respecto al sexo y edad, ni a la provisión de agua corriente y/o de pozo ni a residencia urbana o rural. Si se observó diferencia significativa entre escuelas Estatales y Privadas : 21,2 por ciento y 11,6 por ciento respectivamente. Dado las diferencias observadas entre los distintos equipos de trabajo (todos los profesionales intervinientes con experiencia en palpación de tiroides), se resolvió efectuar ecografía a un 20 por ciento de los positivos más un 10 por ciento de normales : los resultados de las ecografías avalan ampliamente los hallazgos palpatorios. De las 53 muestras de orina procesadas, se observó un promedio de 21,1 mcg/dl de iodo con un desvío standar de 6,7 mcg/dl (es decir, iodurias altamente satisfactorias). Se ha decidido profundizar la investigación, determinando anticuerpos TPO y medición TSH, para destacar tiroiditis crónica e hipotiroidismo subclínico

Prevalencia de bocio en escolares (6 a 14 años) de la ciudad de Mar del Plata / Goiter prevalence in school children (6 to 14 years) of Mar del Plata city

El objetivo de este trabajo fue determinar la prevalencia de bocio en escolares de la ciudad de Mar del Plata. Se seleccionó una muestra entre alumnos de 6 a 14 años de edad de escuelas urbanas y periurbanas de la ciudad de Mar del Plata; la muestra se realizó por conglomerados y posteriormente por métodos aleatorios. Se encuestaron 889 alumnos, 54,1 por ciento de sexo masculino y 45,9 por ciento del femenino, y se recolectó orina en un 8,7 por ciento de los varones. Se detectó un 17,2 por ciento del nivel Ia, 1,7 por ciento Ib y 0,1 por ciento II Total = 19 por ciento (según clasificación OPS). No se observaron diferencias significativas respecto al sexo y edad, ni a la provisión de agua corriente y/o de pozo ni a residencia urbana o rural. Si se observó diferencia significativa entre escuelas Estatales y Privadas : 21,2 por ciento y 11,6 por ciento respectivamente. Dado las diferencias observadas entre los distintos equipos de trabajo (todos los profesionales intervinientes con experiencia en palpación de tiroides), se resolvió efectuar ecografía a un 20 por ciento de los positivos más un 10 por ciento de normales : los resultados de las ecografías avalan ampliamente los hallazgos palpatorios. De las 53 muestras de orina procesadas, se observó un promedio de 21,1 mcg/dl de iodo con un desvío standar de 6,7 mcg/dl (es decir, iodurias altamente satisfactorias). Se ha decidido profundizar la investigación, determinando anticuerpos TPO y medición TSH, para destacar tiroiditis crónica e hipotiroidismo subclínico

Investigacion de contactos en enfermos de sifilis en Mar del Plata, Argentina. / Research on syphilis patients' contacts in Mar del Plata, Argentina

Este estudio trata sobre la importancia del control de contactos en un programa de control de enfermedades de transmision sexual y en el se evalua la actividad como mecanismo de busqueda de casos. Se analiza el material recogido al respecto en el Instituto Nacional de Epidemiologia de Mar del Plata en el periodo de 1971 a 1980

[Efficacy and tolerability of single-dose rosoxacin in the treatment of acute uncomplicated gonorrhea]. / Efficacité et tolérance de la rosoxacine à dose unique dans le traitement de la blennorragie aiguë non compliquée.

61 patients, male and female, with uncomplicated acute gonorrhea were given a single dose of 300 mg rosoxacin (2 capsules). 52 patients only completed clinical and laboratory controls. The drop-out rate for follow-up examinations was 14.8%. 98% of patients were cured. One patient failed to respond to treatment, and six had reinfection seven days later at follow-up control. Three of these were again treated with rosoxacin and cured. Among the side-effects, which were recorded in 24.4% of patients, dizziness was most prevalent (18.1%). Rosoxacin is particularly valuable in gonorrhea, given the single oral dose, the absence of resistance and the high percentage of efficacy.