RESUMO
Evolutionary origins of novel forms are often obscure because early and transitional fossils tend to be rare, poorly preserved, or lack proper phylogenetic contexts. We describe a new, exceptionally preserved enigmatic crab from the mid-Cretaceous of Colombia and the United States, whose completeness illuminates the early disparity of the group and the origins of novel forms. Its large and unprotected compound eyes, small fusiform body, and leg-like mouthparts suggest larval trait retention into adulthood via heterochronic development (pedomorphosis), while its large oar-like legs represent the earliest known adaptations in crabs for active swimming. Our phylogenetic analyses, including representatives of all major lineages of fossil and extant crabs, challenge conventional views of their evolution by revealing multiple convergent losses of a typical "crab-like" body plan since the Early Cretaceous. These parallel morphological transformations may be associated with repeated invasions of novel environments, including the pelagic/necto-benthic zone in this pedomorphic chimera crab.
Assuntos
Artrópodes/anatomia & histologia , Artrópodes/classificação , Evolução Biológica , Fósseis , Adaptação Fisiológica , Animais , Linhagem da Célula , Colômbia , Larva , Filogenia , Natação , Estados UnidosRESUMO
An outbreak of cyclosporiasis occurred in attendees of a wedding reception held in Philadelphia, Pennsylvania, on June 10, 2000. In a retrospective cohort study, 54 (68.4%) of the 79 interviewed guests and members of the wedding party met the case definition. The wedding cake, which had a cream filling that included raspberries, was the food item most strongly associated with illness (multivariate relative risk, 5.9; 95% confidence interval, 3.6 to 10.5). Leftover cake was positive for Cyclospora DNA by polymerase chain reaction analyses. Sequencing of the amplified fragments confirmed that the organism was Cyclospora cayetanensis. The year 2000 was the fifth year since 1995 that outbreaks of cyclosporiasis definitely or probably associated with Guatemalan raspberries have occurred in the spring in North America. Additionally, this is the second documented U.S. outbreak, and the first associated with raspberries, for which Cyclospora has been detected in the epidemiologically implicated food item.
Assuntos
Cyclospora/isolamento & purificação , Ciclosporíase/epidemiologia , Ciclosporíase/parasitologia , Surtos de Doenças , Parasitologia de Alimentos , Frutas/parasitologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Análise por Conglomerados , Comércio , DNA de Protozoário , Feminino , Manipulação de Alimentos , Doenças Transmitidas por Alimentos/epidemiologia , Doenças Transmitidas por Alimentos/parasitologia , Guatemala , Humanos , Masculino , Pessoa de Meia-Idade , Philadelphia/epidemiologia , Reação em Cadeia da PolimeraseRESUMO
BACKGROUND: Cerebral malaria is an important cause of pediatric hospital admissions in the tropics. It commonly leads to neurologic sequelae, but the risk factors for this remain unclear and the long-term outcome unknown. OBJECTIVE: The purpose of this study was to identify the common forms of neurologic sequelae that occur after cerebral malaria, their evolution over time, and the major clinical risk factors for residual disability. STUDY DESIGN: Prospective study in 624 children admitted with cerebral malaria to two hospitals in The Gambia, West Africa. RESULTS: We found that 23.3% of survivors had neurologic sequelae on discharge from the hospital. By 1 month the proportion had decreased to 8.6%, and at 6 months only 4.4% of survivors were found to have residual neurologic sequelae. The most common forms of neurologic sequelae were paresis and ataxia, often found in combination with other neurologic abnormalities. In a multiple logistic regression analysis, depth of coma on admission, multiple convulsions, and duration of unconsciousness were the only three independent risk factors. Hypoglycemia and lactate acidosis were not predictive of sequelae, although they are important risk factors for fatality. CONCLUSION: This finding raises the possibility that fatal outcome and neurologic sequelae arise from separate pathologic processes.
Assuntos
Artemisininas , Encefalopatias/etiologia , Malária Cerebral/complicações , Acidose Láctica/etiologia , Acidose Láctica/fisiopatologia , Antimaláricos/uso terapêutico , Artemeter , Ataxia/etiologia , Encefalopatias/fisiopatologia , Causas de Morte , Criança , Pré-Escolar , Coma/etiologia , Coma/fisiopatologia , Feminino , Previsões , Gâmbia , Humanos , Hipoglicemia/etiologia , Hipoglicemia/fisiopatologia , Lactente , Modelos Logísticos , Estudos Longitudinais , Malária Cerebral/tratamento farmacológico , Malária Cerebral/fisiopatologia , Masculino , Paresia/etiologia , Admissão do Paciente , Alta do Paciente , Estudos Prospectivos , Quinina/uso terapêutico , Fatores de Risco , Convulsões/etiologia , Convulsões/fisiopatologia , Sesquiterpenos/uso terapêutico , Taxa de Sobrevida , Fatores de Tempo , Resultado do Tratamento , Clima Tropical , Inconsciência/etiologia , Inconsciência/fisiopatologiaRESUMO
OBJECTIVE: To determine the best method of oxygen delivery for children in developing countries who have hypoxemia caused by acute lower respiratory tract infection. METHODS: One hundred eighteen children between 7 days and 5 years of age with a lower respiratory tract infection and arterial hemoglobin oxygen saturation (Sao2) less than 90% were randomly selected to receive oxygen by nasopharyngeal (NP) catheter (n = 56) or nasal prongs (n = 62). A crossover study to determine the flow rate necessary to achieve an Sao2 of 95% was performed in 60 children. RESULTS: One hundred twelve children could be oxygenated by the allocated method; in six oxygenation was poor with either method. The mean duration of therapy was 87.5 hours for the prongs and 94.9 hours for the NP catheter (not significant). The median oxygen consumption was 2142 L for prongs and 1692 L for the NP catheter (not significant). In the crossover study the prongs needed, on average, 26% higher oxygen flow rates than the NP catheter to obtain an Sao2 of 95% (p = 0.003). Complete nasal obstruction was observed in 24 of the children (44%) in the NP catheter group and in 8 (13%) in the prongs group (p < 0.001). Eighteen children died, 11 with NP catheter and 7 with prongs (not significant). CONCLUSIONS: Because nasal prongs are less prone to complications, and oxygenation in children is equally effective, they are a more appropriate method than the NP catheter for oxygen delivery to children in developing countries with acute lower respiratory tract infections.
Assuntos
Cateterismo Periférico/instrumentação , Hipóxia/terapia , Oxigenoterapia/instrumentação , Infecções Respiratórias/terapia , Cateterismo Periférico/efeitos adversos , Cateterismo Periférico/métodos , Cateterismo Periférico/enfermagem , Cateterismo Periférico/estatística & dados numéricos , Distribuição de Qui-Quadrado , Pré-Escolar , Estudos Cross-Over , Humanos , Hipóxia/etiologia , Hipóxia/enfermagem , Lactente , Recém-Nascido , Nasofaringe , Oxigenoterapia/efeitos adversos , Oxigenoterapia/métodos , Oxigenoterapia/enfermagem , Oxigenoterapia/estatística & dados numéricos , Infecções Respiratórias/complicações , Infecções Respiratórias/enfermagem , Segurança , Estatísticas não Paramétricas , Resultado do TratamentoRESUMO
Because the validity of the use of preaccumulated isotopic excitatory amino acids (EAAs) to index the depolarization-evoked release of endogenous EAAs has been questioned, we compared the K(+)-evoked efflux of preaccumulated D-[3H]aspartate from rat cerebrocortical minislices with that of endogenous L-aspartate and L-glutamate. Release of all EAAs increased with the rate of superfusion. Using the most rapid rate (1.6 ml/min), transient elevations in [K+] caused a concentration-dependent increase, with 50 mM K+ evoking a 33-, 23- and 93-fold increase in the efflux of D-[3H]aspartate, L-aspartate and L-glutamate, respectively; this efflux was Ca(2+)-dependent and tetrodotoxin insensitive. Under polarized conditions (5 mM K+), 1 mM kainic acid increased the efflux of preaccumulated and endogenous EAAs. These elevations were not blocked by the competitive kainate receptor antagonist 6,7-dinitroquinoxaline-2-3-dione (DNQX) and were not affected by removing Ca2+ ions. We conclude that in superfused cortical minislices, the efflux of preaccumulated D-[3H]aspartate provides a robust and reliable index of the release of endogenous L-aspartate and L-glutamate.
Assuntos
Ácido Aspártico/metabolismo , Córtex Cerebral/metabolismo , Ácido Glutâmico/metabolismo , Animais , Transporte Biológico/efeitos dos fármacos , Cálcio/metabolismo , Técnicas In Vitro , Ácido Caínico/farmacologia , Masculino , Potássio/farmacologia , Quinoxalinas/farmacologia , Ratos , Ratos Sprague-Dawley , Estereoisomerismo , Tetrodotoxina/farmacologiaRESUMO
This study used [3H]dizocilpine (MK-801) binding to the N-methyl-D-aspartate (NMDA) receptor to examine glycine, redox and zinc modulatory sites in membranes derived from the frontal and parietal cortex of control subjects (n = 8) and suicide victims (n = 6). [3H]dizocilpine binding in the presence of glutamate and glutamate plus glycine was similar in control and suicide subjects. The sulphydryl redox site was assessed using the oxidizing agent 5,5'-dithio-bis (2-nitrobenzoic acid), which inhibited binding in a dose-dependent fashion. Both redox and zinc sites were unaffected in the frontal and parietal cortex of suicide victims. These data indicate that the NMDA receptor and its glycine, redox and zinc subsites are preserved in the neocortex of suicide victims.
Assuntos
Química Encefálica , Maleato de Dizocilpina/metabolismo , Glicina/farmacologia , Receptores de N-Metil-D-Aspartato/efeitos dos fármacos , Suicídio , Zinco/farmacologia , Adulto , Feminino , Lobo Frontal/química , Ácido Glutâmico/farmacologia , Humanos , Canais Iônicos/efeitos dos fármacos , Masculino , Oxirredução , Receptores de N-Metil-D-Aspartato/metabolismoRESUMO
The integrity of dopaminergic, noradrenergic and serotonergic neurons in normal aging and Alzheimer's disease is reviewed. Loss of dopaminergic innervation of the neostriatum is a prominent age-related change, which corresponds with the age-related loss of dopaminergic cell bodies from the substantia nigra. This change is regionally specific, since dopaminergic innervation of the neocortex and the neostriatum are not affected. Although there is an age-related loss of noradrenergic cell bodies from the locus coeruleus, most studies indicate normal concentrations of noradrenaline in target areas. There is also evidence for reduced serotonergic innervation of the neocortex and, less convincingly, the neostriatum. Alzheimer's disease is associated with more pronounced noradrenergic and serotonergic denervation but, unlike normal aging, dopaminergic innervation of neostriatum is intact; although dopamine neurons are probably dysfunctional in this region. Studies relating neuronal markers to the symptomatology of Alzheimer's disease indicate that dysfunction of monoamine neurons is more closely linked to non-cognitive than to cognitive changes in behavior. In addition, monoaminergic therapies have been successful in ameliorating affective and psychotic behaviors along with sleep disturbances in both Alzheimer's disease and senescence. It seems likely that monoaminergic therapies (developed as we learn more about alterations in dopamine, noradrenaline and serotonin) will continue to be necessary to treat such behavioral disturbances.