Mechanisms and ecological consequences of plant defence induction and suppression in herbivore communities.

BACKGROUND: Plants are hotbeds for parasites such as arthropod herbivores, which acquire nutrients and energy from their hosts in order to grow and reproduce. Hence plants are selected to evolve resistance, which in turn selects for herbivores that can cope with this resistance. To preserve their fitness when attacked by herbivores, plants can employ complex strategies that include reallocation of resources and the production of defensive metabolites and structures. Plant defences can be either prefabricated or be produced only upon attack. Those that are ready-made are referred to as constitutive defences. Some constitutive defences are operational at any time while others require activation. Defences produced only when herbivores are present are referred to as induced defences. These can be established via de novo biosynthesis of defensive substances or via modifications of prefabricated substances and consequently these are active only when needed. Inducibility of defence may serve to save energy and to prevent self-intoxication but also implies that there is a delay in these defences becoming operational. Induced defences can be characterized by alterations in plant morphology and molecular chemistry and are associated with a decrease in herbivore performance. These alterations are set in motion by signals generated by herbivores. Finally, a subset of induced metabolites are released into the air as volatiles and function as a beacon for foraging natural enemies searching for prey, and this is referred to as induced indirect defence. SCOPE: The objective of this review is to evaluate (1) which strategies plants have evolved to cope with herbivores and (2) which traits herbivores have evolved that enable them to counter these defences. The primary focus is on the induction and suppression of plant defences and the review outlines how the palette of traits that determine induction/suppression of, and resistance/susceptibility of herbivores to, plant defences can give rise to exploitative competition and facilitation within ecological communities "inhabiting" a plant. CONCLUSIONS: Herbivores have evolved diverse strategies, which are not mutually exclusive, to decrease the negative effects of plant defences in order to maximize the conversion of plant material into offspring. Numerous adaptations have been found in herbivores, enabling them to dismantle or bypass defensive barriers, to avoid tissues with relatively high levels of defensive chemicals or to metabolize these chemicals once ingested. In addition, some herbivores interfere with the onset or completion of induced plant defences, resulting in the plant's resistance being partly or fully suppressed. The ability to suppress induced plant defences appears to occur across plant parasites from different kingdoms, including herbivorous arthropods, and there is remarkable diversity in suppression mechanisms. Suppression may strongly affect the structure of the food web, because the ability to suppress the activation of defences of a communal host may facilitate competitors, whereas the ability of a herbivore to cope with activated plant defences will not. Further characterization of the mechanisms and traits that give rise to suppression of plant defences will enable us to determine their role in shaping direct and indirect interactions in food webs and the extent to which these determine the coexistence and persistence of species.

Obstructive sleep apnea severity correlates with cellular and plasma oxidative stress parameters and affective symptoms.

Obstructive sleep apnea syndrome (OSAS) is considered a sleep-related respiratory disorder, characterized by repetitive episodes of complete (apnea) or partial (hypopnea) obstruction of airflow in the upper airway (UA) during sleep. The pathophysiology of upper airway obstruction in OSAS is multifactorial, leading to a chronic recurrent state of intermittent hypoxemia and reoxygenation during sleep, maintaining a state of oxidative stress, which seems to be the key to the pathophysiological manifestations of OSAS, and is associated with the development of a number of high morbidity-mortality systematic complications, such as obesity, type 2 diabetes, metabolic syndrome, and cardiovascular and neuropsychological diseases. This study is an open, cross-sectional, and comparative clinical trial, whose general objective was to assess the correlation between OSAS severity, oxidative stress markers, and the presence of affective symptoms (depressive and anxious) in OSAS patients. We studied 38 adult males, who had been diagnosed with OSAS by overnight polysomnography, between 18 and 60 years of age, divided into three groups: group 1-10 individuals with mild OSAS (AHI between 5 and 14.9/h), group 2-13 individuals with moderate OSAS (AHI between 15 and 30/h), and group 3-15 individuals with severe OSAS (AHI >30/h). All individuals were evaluated for level of subjective sleepiness using the Epworth Sleepiness Scale, for depressive and anxiety symptoms by the Hamilton Depression (HAM-D) and Anxiety (HAM-A) Scales, and for parameters of the oxidative stress state, measuring superoxide radical and serum nitrates and nitrites levels. There was a progressive and significant increase in the state of oxidative stress (p < 0.05), in the total score of depressive symptoms (p = 0.001) and in the overall score of anxiety symptoms (p = 0.004) directly proportional to the severity of apnea when comparing the mild group to the severe group. Positive correlations were identified between superoxide production and the apnea-hypopnea index (AHI) (r = 0.48), Epworth sleepiness score (r = 0.36), and Hamilton depression score (HAM-D) (r = 0.40); between serum nitrates and nitrites levels and SO(2) min (r = 0.44); and between the AHI and the HAM-D (r = 0.51) score and HAM-A (r = 0.40) score. Negative correlations were observed between the AHI and serum nitrates and nitrites levels (r = -0.42), between superoxide production and SO(2) min (r = -0.31), between serum nitrates and nitrites levels and HAM-D (r = -0.50) and HAM-A (-0.42) scores, and between SO(2) min and HAM-D (r = -0.48) and HAM-A (r = -0.40) scores. According to the results of this study, we can conclude that (1) individuals with OSAS show an increase in the production of superoxide radical and a decrease in serum nitrates and nitrites levels, which are objective signs of a state of oxidative stress. (2) The more severe the OSAS, the more fragmented the sleep and the greater the nocturnal hypoxemia, the more severe is the oxidative stress state and the greater is the incidence of daytime symptoms, especially sleepiness and depressive and anxiety symptoms. Future studies might explore the investigation of oxidative stress parameters as an alternative approach to anticipate symptoms, measure prognosis, and monitor OSAS progression or treatment response.

Neuropatia toxica aguda acidental por chumbo e mercurio: estudo em duas familias. / Toxic acute accidental neuropathy by lead and mercury: study in 2 families

Foram estudadas duas familias, vitimas de intoxicacao aguda acidental por inalacao da queima de lixo industrial, em outubro de 1981 nos arredores da cidade de Paulista (PE). As familias inalaram os gases em suas residencias durante um periodo de cerca de 15 horas. Das doze pessoas (5 do sexo masculino e 7 do sexo feminino) duas eram gestantes. Houve 03 obitos.O diagnostico foi baseado na historia clinica, exames toxicologicos e eletrofisiologicos. A analise quimica dos residuos do citado lixo industrial, demonstrou os seguintes teores de chumbo e mercurio: em 17 gr. de material metalico usado em bocais de lampadas comuns havia 6gr. de Pb (Tecnica de Saulsby e Smith). Em 16gr. da filamentos de lampadas comuns havia 0,2gr. de Pb (pela mesma tecnica).Em 4gr. de vidro de lampadas comuns havia 0,576gr. de Hg (Tecnica de Kaye). Os metais pesados foram dosados no sangue, urina, fezes e LCR em varios casos pelas mesmas tecnicas respectivamente supracitadas

Sindromes neurologicas paraneoplasicas. / Neurological paraneoplastic syndromes

Breve historico e um resumo dos quadros neurologicos paraneoplasicos sao apresentados pelo autor, bem como a pequena experiencia em uma serie aleatoria de 51 casos de neoplasias de localizacoes variadas, na qual sao encontradas 8 neuropatias paraneoplasicas: 3 sindromes cordonais posteriores, 3 miopatias carcinomatosas, 1 polineuropatia sensitivo-motora e 1 sindrome confusional relacionada com um tumor carcinoide do apendice

Issues concerning parents after the death of their newborn.

Thirty-five families were interviewed by members of the intensive care nursery staff 2-4 months after the death of their newborn. Of the families interviewed, 74% wanted to review the events leading to their child's death and ask questions about information they already knew. Most families who were interested in the autopsy findings used the results to find out "how normal everything else was." Topics frequently discussed by parents involved feelings of guilt and problems that arose after the infant's death (isolation by friends, somatic complaints, marital and sexual problems, memories of prior losses, problems with siblings and disposal of baby's things). One-third of the families were felt to need continuing emotional support due to their inability to assume previously accepted responsibilities. For many families, the physician may be the only individual who can tolerate listening to their distress.

Do parents utilize physician follow-up after death of their newborn?

Numerous authors have advocated appropriate physician-patient counseling following a perinatal death. We examined, in a prospective manner, how many families utilized physician follow-up when such follow-up was offered. Seventy-six percent of the 108 families who experienced a neonatal death chose to have physician follow-up in the weeks after the death. A family's utilization of subsequent physician contact was not related to the distance they lived from the medical center, the duration of survival of the infant, or the racial background of the mother. Parents utilized follow-up visits whether or not an autopsy was performed or an interpreter was needed. Certain features distinguished the parents who did not utilize the physician follow-up service: parents were less likely to utilize the service if they were not married, the mother was a teenager, the head of the household was unemployed, or there was no phone at home.

Follow-up families who experience a perinatal death.

We conducted a retrospective study by telephone interview (10 to 22 months later) of 26 families who had experienced a perinatal death. Six of 26 mothers had a prolonged grief reaction (12 to 20 months). Those mothers with a surviving twin or subsequent pregnancy less than five months following the death were at higher risk for a prolonged grieving period than were those without subsequent pregnancy or one more than six months later. Half of the families obtained information about the cause of death and risk of recurrence only during hospitalization; subsequent contact, weeks to months later, provided additional information for the other half. Twenty-two of 26 mothers met predetermined criteria for having an adequate understanding of cause of death and risk of recurrence; four of 26 knew neither. Sixty percent of the mothers who had adequate understanding and who had no prolonged grief response felt totally dissatisfied or only partially satisfied with the information they received and the way they received it. Follow-up contact by phone or in person increased understanding significantly; mothers who had had in-person follow-up were more likely to be satisfied with the information they received.