The fetal llama exposed to an intense degree of hypoxaemia did not increase cerebral blood flow, but showed a marked peripheral vasoconstriction. The same cardiovascular response is observed in fetal sheep submitted to a extremely severe hypoxaemia, when the initial compensatory vasodilatory mechanisms in brain and heart fail. To investigate whether the fetal llama responses to acute hypoxaemia are adaptive, or whether they are the result of a breakdown of mechanisms of blood flow redistribution that favours the central nervous system, we studied seven fetal llamas (0.6-0.7 of gestation) chronically-catheterized during 1 h of graded and progressive hypoxaemia. Fetal ascending aorta blood gases and fetal cardiac output and its distribution (radiolabelled-microspheres) were measured after 60 min of normoxaemia (B) and at the end of 20 min (H20), 40 min (H40) and 60 min (H60) of hypoxaemia. Data were analysed by ANOVA and Newman-Keuls tests. Each treatment resulted in a lower (P < 0.05) percentage of haemoglobin saturation than hypoxaemia; H40 was lower than H20, and H60 was lower than H20 and H40. No statistical difference was observed among treatments for cardiac output or cerebral blood flow. These results demonstrate that fetal cardiac output and brain blood flow are maintained at all degrees of hypoxaemia, indicating that these cardiovascular responses are an adaptive response in the llama fetus, rather than an index of cardiorespiratory decompensation.
Preliminary studies showed that dorsal artery contraction mediated by acetylcholine (ACh) is blocked with indomethacin in intertidal fish (Girella laevifrons). Our objective was to characterise the cholinergic pathway in several artery vessels of the G. laevifrons. Afferent and efferent branchial, dorsal and mesenteric arteries were dissected of 6 juvenile specimens, isometric tension studies were done using dose response curves (DRC) for Ach (10 -13 to 10 -3 M), and cholinergic pathways were obtained by blocking with atropine or indomethacin. CRC to ACh showed a pattern of high and low sensitivity. Furthermore, these contractions were blocked in the presence of atropine and indomethacin in all vessels. Our results suggest that contraction observed with acetylcholine is mediated by receptors that activate a cyclooxygenase contraction pathway.Keywords: intertidal fish, vascular reactivity, acetylcholine, atropine, indomethacin, cycloxygenase. Função vascular nas artérias do peixe marinhoGirella laevifrons (Kyphosidae) ResumoEstudos preliminares mostraram que a contração da artéria dorsal mediada por acetilcolina (ACh) é bloqueada com indometacina em peixes marinhos Girella laevifrons. Nosso objetivo foi caracterizar a via colinérgica em várias artérias de G. laevifrons. Artérias aferentes e eferentes branquiais, dorsais e mesentéricas foram dissecadas de 6 espécimes juvenis. Os estudos de tensão isométrica foram feitos utilizando-se a curva dose -resposta (CDR) para Ach (10 -13 a 10 -3 M), e identificaram-se as vias colinérgicas, bloqueando com atropina e indometacina. CRC para ACh mostrou um padrão de alta e baixa sensibilidade. Essas contrações foram bloqueadas na presença de atropina e indometacina em todas as artérias avaliadas. Nossos resultados sugerem que a contração observada com acetilcolina é mediada por receptores muscarínicos que ativam uma ciclo-oxigenase.
As a result of the increased incidence of osteopenia and osteoporosis in HIV-infected patients, numerous publications have suggested that there may be a link between bone metabolism alterations and HIV infection. The early bone loss seen in these patients was initially attributed to the use of highly active antiretroviral treatment (HAART) that included protease inhibitors. Recent studies, however, have suggested that it may be a direct consequence of the viral infection on bone metabolism, persistent activation of pro-inflammatory cytokines (TNFa), or altered vitamin D metabolism secondary to the virus, combined with subsequent factors (e.g., antiretroviral treatment) that aggravate the bone demineralization. We present an antiretroviral-naive 6-year-old girl with vertically transmitted HIV infection who presented with severe osteoporosis and multiple pathological fractures of the vertebrae, ribs, and upper and lower limbs. The child was treated with HAART, appropriate nutritional support for her age, physiotherapy and rehabilitation, calcium and vitamin D supplements, and alendronate therapy. After 6 weeks of treatment, the intense pain and muscle atrophy had disappeared and she was able to walk unassisted. At 6 months, bone mass had increased by 72%. The interest of this case lies in the presence of severe osteoporosis and multiple pathological fractures in an HIVinfected naive child. To date, this condition has only been described in patients treated with antiretrovirals. Moreover, this is the first reported HIV-positive pediatric patient treated with bisphosphonates, which proved to be highly successful.
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