Noachian and more recent phyllosilicates in impact craters on Mars.

Hundreds of impact craters on Mars contain diverse phyllosilicates, interpreted as excavation products of preexisting subsurface deposits following impact and crater formation. This has been used to argue that the conditions conducive to phyllosilicate synthesis, which require the presence of abundant and long-lasting liquid water, were only met early in the history of the planet, during the Noachian period (> 3.6 Gy ago), and that aqueous environments were widespread then. Here we test this hypothesis by examining the excavation process of hydrated minerals by impact events on Mars and analyzing the stability of phyllosilicates against the impact-induced thermal shock. To do so, we first compare the infrared spectra of thermally altered phyllosilicates with those of hydrated minerals known to occur in craters on Mars and then analyze the postshock temperatures reached during impact crater excavation. Our results show that phyllosilicates can resist the postshock temperatures almost everywhere in the crater, except under particular conditions in a central area in and near the point of impact. We conclude that most phyllosilicates detected inside impact craters on Mars are consistent with excavated preexisting sediments, supporting the hypothesis of a primeval and long-lasting global aqueous environment. When our analyses are applied to specific impact craters on Mars, we are able to identify both pre- and postimpact phyllosilicates, therefore extending the time of local phyllosilicate synthesis to post-Noachian times.

Clinical and epidemiological aspects of children hospitalized with severe rotavirus-associated gastroenteritis in Salvador, BA, Brazil

Little is known about the epidemiology of severe rotavirus-associated gastroenteritis in Brazil. Given the morbidity associated with this condition and the importance of having detailed knowledge about the impact of rotavirus infection on the epidemiology of acute diarrhea in children, especially those with the most severe diarrheal conditions, we retrospectively reviewed the medical records of all pediatric patients admitted to a tertiary hospital in Salvador, Brazil, due to rotavirus-associated gastroenteritis during one year. It was observed that rotavirus was responsible for 15.6 percent of the hospitalizations caused by diarrhea and/or vomiting during the period of the study and that 87 of 218 (39.1 percent) patients seen at the emergency room with rotavirus-associated gastroenteritis needed to be hospitalized, comprising the population of our study. Most patients presented signs of dehydration, and 41 percent of them had metabolic acidosis. Most patients (79 percent) were between six months and four years of age and 72 percent of the cases occurred in June and July. Gastrointestinal symptoms were rarely present at the beginning of the clinical presentation, and they normally did not last for more than one week.

Clinical and epidemiological aspects of children hospitalized with severe rotavirus-associated gastroenteritis in Salvador, BA, Brazil.

Little is known about the epidemiology of severe rotavirus-associated gastroenteritis in Brazil. Given the morbidity associated with this condition and the importance of having detailed knowledge about the impact of rotavirus infection on the epidemiology of acute diarrhea in children, especially those with the most severe diarrheal conditions, we retrospectively reviewed the medical records of all pediatric patients admitted to a tertiary hospital in Salvador, Brazil, due to rotavirus-associated gastroenteritis during one year. It was observed that rotavirus was responsible for 15.6% of the hospitalizations caused by diarrhea and/or vomiting during the period of the study and that 87 of 218 (39.1%) patients seen at the emergency room with rotavirus-associated gastroenteritis needed to be hospitalized, comprising the population of our study. Most patients presented signs of dehydration, and 41% of them had metabolic acidosis. Most patients (79%) were between six months and four years of age and 72% of the cases occurred in June and July. Gastrointestinal symptoms were rarely present at the beginning of the clinical presentation, and they normally did not last for more than one week.

Non-specific febrile illness by Coxsackievirus A16 in a 6-day-old newborn.

A case of non-specific febrile illness by Coxsackievirus A 16 (CA 16) in a 6-day-old newborn whose mother had developed hand, foot and mouth disease manifestations 2 days after delivery is reported. Notwithstanding the concurrence of negative circumstances like the presence of the enterovirus genome in the cerebrospinal fluid, absence of type specific neutralizing antibody and a few days of life, the newborn recovered 3 days after the onset of fever. This case, also characterized by the absence of mucosal and cutaneous erythematous manifestations typical of CA16 infection, draws attention to the possibility that non-specific febrile illness in newborns usually suspected of bacterial origin may have an enteroviral cause.

Diagnosis of central precocious puberty: endocrine assessment.

The new methods which are currently available have provided substantial help in performing the differential diagnosis of CPP, especially in detecting very early modifications of gonadotropin secretion. Nocturnal sampling is not a practical tool and generates discomfort for patients, and daytime samples do not yet have sufficient sensitivity; thus, determination of LH levels after GnRH stimulation is the most important test. We emphasize that the use of the GnRH agonist test improves the discrimination of the endocrine investigation, making it easier to differentiate CPP from other conditions, such as thelarche. Determination of sex steroids is necessary, but its use in isolation is not recommended.

[Schönlein-Henoch syndrome: clinical-epidemiological analysis of 98 cases]. / Sindrome di Schönlein-Henoch: analisi clinico-epidemiologica su 98 casi.

We analyzed the clinical and epidemiological data of 98 patients (50 males and 48 females) aged between 6 months and 16 years, hospitalized for Schönlein-Henoch syndrome in the last 20 years. The incidence was higher during spring time. Throat culture was positive for streptococcus pyogenes in 16% of patients. 14 of 60 (23%) had a positive allergometric response to various tests. The extrarenal manifestations were: purpura (100%), articular (68%) or gastrointestinal (32%) involvement and orchitis (10%). Renal symptoms were observed in 23% of the patients, but a clear nephropathy was documented just in 5% of the cases, with resolution within 2 years. Our data suggest, in agreement with the letterature, that renal involvement in Schönlein-Henoch syndrome has usually a benign course.

Genetics and molecular biology of the GHRH-GH-IGF-I axis.

In this paper, the genetics and molecular biology of the GHRH-GH-IGF-I (Growth Hormone Releasing hormone-Growth Hormone-Insulin like Growth Factor I) axis involved in the pathogenesis of short stature are reviewed. Short stature associated with GH deficiency is estimated to occur in about 1/4000-10,000 live births; 3-30% of cases affect first-degree relatives, suggesting a genetic aetiology. Identification of such molecular defects is very recent and dependent on new findings on the physiology of GHRH-GH-IGF-I axis: for example the pituitary-specific transcription factors and their mutations have only been described in the last few years. The epidemiological importance of the identified molecular defect depends on the level of the axis involved, but the prevalence of some of these genetic defects is probably underestimated. Time will tell what the practical relevance of these findings is and what the clinical features of the new mutations are; we will probably learn something more about the GHRH-GH-IGF-I axis: to date, no mutations have been reported regarding the GHRH gene or the IGF-I receptor.

[HIV infection and the endocrine system in children]. / Infezione da HIV e sistema endocrino nel bambino.

HIV infected children characteristically develop a failure to thrive in 25% to 100% of symptomatic cases, with a significantly reduced survival time. The pathogenic mechanism for HIV-driven failure to thrive is not yet understood. Likely it is multifactorial, endocrine dysregulation surely plays a major, even if not yet fully clarified, role in this complication. Global evaluation of endocrine data could allow to better understand the mechanisms underlying the failure to thrive in HIV-infected children, also in relationship with the current manifestations of the HIV infection. The results of the endocrine studies could also be related with additional features of the children, as their immunological status. It is well known that endocrine and immune functions are closely related in animals and in humans. Thus, the evaluation of the results of studies could provide some interesting information about the relationships between them in the HIV-infected child. Such relationships, if present, also could help to better define therapeutic interventions in these children.