Prevalence of mental disorders and psychosocial impairments in adolescents and young adults

Graves' disease is the predominant cause of hyperthyroidism in the pediatric age group. Other disorders must be recognized, however, because adequate management relies on a precise diagnosis. Careful monitoring of the thyroid status is required during this active phase of growth and development.     

Using chromosomal lacIQ1 to control expression of genes on high-copy-number plasmids in Escherichia coli

Tachykinin NK1 receptor antagonists injected into the medulla oblongata are known to abolish vomiting induced by vagal afferent stimulation. Emetic vagal afferents have been shown to synapse with neurons in the medial solitary nucleus (mNTS), which suggests that substance P is a transmitter in the synapse. To examine this possibility, the effects of GR205171, an NK1 receptor antagonist, on retching and mNTS neuronal responses to the stimulation of abdominal vagal afferents were investigated in decerebrate dogs. GR205171 (0.05-0.7 mg kg-1, i.v.) abolished retching induced by either vagal or mNTS stimulation within 5 min. Firing of mNTS neurons in response to pulse-train and sustained vagal stimulation did not change even after the abolition of retching. Similarly, GR205171 did not have any effects on mNTS evoked potentials induced by pulse-train vagal stimulation. In about 20% of mNTS neurons, the peak firing frequency was facilitated to about 150% with repetitive pulse-train vagal stimulation. This facilitation remained even after the abolition of retching. Administration of GR205171 (1 mg ml-1, 30 microliters) into the 4th ventricle abolished retching, with latencies in excess of 120 min These results suggest that substance P does not participate in synaptic transmission between emetic vagal afferents and mNTS neurons in dogs.     

Asthmatic exacerbations and environmental pollen concentration in La Comarca Lagunera (Mexico)

In order to determine the correlation between the concentration of environmental pollen and the frequency of asthmatic exacerbations in La Comarca Lagunera (México), a study in a cohort of a 104 diagnosed patients suffering allergic asthma was carried out monitoring monthly from July '93 to July '95 in order to register the existence of asthmatic exacerbations. Environmental samples were taken weekly during the same period of time through a PST high volume collector (Andersen Samplers Inc). The above mentioned samples were processed under acetolysis technics and the pollen grain count under light microscopy. Linear correlation measures were made between the rates of asthmatic exacerbations and the concentration of pollen grain in m3 of air by means of a statistical computer program SAS. There was a 1469 persons/month follow up ('X 15.5) and the correlation between the rates of asthmatic exacerbations and the concentration of environmental pollen was relevant (r = 0.63, r2 = 0.39, p < 0.01). The correlation increased (r = 0.70, r2 = 0.49 and p < 0.01) when the asthmatic exacerbations associated to infectious disease in the upper respiratory system were restricted. The conclusion reached is that the concentration of environment pollen has influence in the development of asthmatic exacerbations in patients with allergic asthma.     

Role of urinary and cloacal bladders in chelonian water economy: historical and comparative perspectives

The Parisian comparative anatomist Claude Perrault, dissecting an Indian giant tortoise in 1676, was the first to observe that the urinary bladder is of an extraordinary size in terrestrial tortoises. In 1799, the English comparative physiologist Robert Townson suggested that the bladder functioned as a water reservoir, as he had shown previously for frogs and toads. However, these observations went unnoticed in subsequent reports on tortoise water economy that were made by travellers and naturalists visiting the Galapagos Archipelago and marvelling over the huge numbers of giant tortoises that inhabited these desert-like islands. The first such report was by an American naval officer, David Porter, who was a privateer in the 1812-15 war with England. In his journal he referred to the constant supply of water which the Galapagos tortoises carried with them. References to the location in the body, as well as the amounts and quality of the water stored, were, however, contradictory. The confusion concerning the anatomical identity of the water reservoir in the Galapagos tortoise, Geochelone elephantopus, persisted throughout the nineteenth century, and continued when studies of tortoise water economy and drinking behaviour in arid environments were taken up independently in the desert tortoise, Gopherus agassizii, which inhabits the desert regions in the south-western United States. In 1881 Cox found large sacs filled with clear water under the carapace, but it was half a century later that these sacs were identified as the large bilobed bladder; references to specific water sacs continued to appear in the literature until the 1960s. Since 1970, information on the water economy of desert tortoises has been obtained from extensive field studies. Rates of disappearance of tritiated water injected into the body have shown that during the drought periods of the summer, water turnover (intake) rates do not differ from the rates of metabolic water production. Under these conditions urine is not voided, but is stored in the large bladder. During a drought period the bladder urine increases from initially low osmolality finally to reach isosmolality with the blood plasma. Soluble K+ is the major cation of the urine, but large amounts of K+ are also present as precipitated urates. During a drought period the body is in negative water balance, but despite substantial losses of total body water, the plasma concentrations of Na+ and Cl- can remain constant for many months, indicating regulation of the extracellular fluid and water content of the body tissues by reabsorption of water from the urinary bladder. The bladder thus acts both as a store for nitrogenous waste and K+ and as a water reservoir during droughts. Following rain showers, there is a sharp decline in tritium activity correlated with copious drinking from temporary pools of rain water. The old bladder urine is voided and most of the water drunk is stored as a highly dilute urine. In 1676 Perrault observed that in a freshwater turtle, Emys orbicularis, but not in the giant tortoise, two other bladders opened into the cloaca. By the mid-twentieth century it had been established that these cloacal bladders typically were restricted to species of chelonians that led a semi-terrestrial or semi-aquatic life. The function of the bladders has been debated since Townson observed in 1799 that dehydrated freshwater turtles took up water by anal drinking, suggesting that anal drinking served in the water economy of semi-terrestrial turtles. Since then, the bladders have been ascribed hydrostatic and respiratory functions, but the recent literature mostly argues for a respiratory function. The possible role of the cloacal bladders as a water reservoir in amphibious turtles is still open. Terrestrial amphibians and tortoises are unique among vertebrates in possessing large urinary bladders that may function as water reservoirs in dry environments. (ABSTRACT TRUNCATED)     

STZ transport and cytotoxicity. Specific enhancement in GLUT2-expressing cells

The glucose analog streptozotocin (STZ) has long been used as a tool for creating experimental diabetes because of its relatively specific beta-cell cytotoxic effect, but the mechanism by which systemic injection of STZ causes beta-cell destruction is not well understood. In the current study, we have used insulinoma (RIN) and AtT-20ins cell lines engineered for overexpression of GLUT2 or GLUT1 to investigate the role of glucose transporter isoforms in mediating STZ cytotoxicity. The in vivo effects of STZ were evaluated by implantation of RIN cells expressing or lacking GLUT2 into athymic nude rats. The drug had a potent cytotoxic effect on RIN cells expressing GLUT2, but had no effect on cells lacking GLUT2 expression, as indicated by histological analysis and measurement of the blood glucose levels of treated animals. The preferential cytotoxic effect of STZ on GLUT2-expressing cell lines was confirmed by in vitro analysis of GLUT2-expressing and untransfected RIN cells, as well as GLUT2- and GLUT1-overexpressing AtT-20ins cells. Consistent with these data, only GLUT2-expressing RIN or AtT-20ins cells transported STZ efficiently. We conclude that expression of GLUT2 is required for efficient killing of neuroendocrine cells by STZ, and this effect is related to specific recognition of the drug as a transported substrate by GLUT2 but not GLUT1.     

Lymphosarcoma of the frontal sinus and nasal passage in a cow

A 5-year-old cow was evaluated because of a 2-week history of ataxia and other vague neurologic signs. Previous treatments included intravenous and orally administered calcium, but improvement was not seen. Bilateral mucoserous nasal discharge and a pair of firm, smooth masses caudodorsal to the eyes were found on the frontal bones on physical examination. The cow's condition deteriorated rapidly within 48 hours; head pressing and inability to rise were observed. The frontal sinuses were radiographically normal. Trephination of the frontal sinuses revealed a space-occupying mass that was interpreted on histologic examination to be lymphosarcoma. Other evidence of neoplasia was not discovered on gross necropsy or histologic examination. Primary lymphosarcoma has not been described at this location in cows. Clinically it resembles chronic frontal sinusitis, and trephination may be necessary to differentiate the 2 diseases.