Environmental drivers of increased ecosystem respiration in a warming tundra.

Arctic and alpine tundra ecosystems are large reservoirs of organic carbon1,2. Climate warming may stimulate ecosystem respiration and release carbon into the atmosphere3,4. The magnitude and persistency of this stimulation and the environmental mechanisms that drive its variation remain uncertain5-7. This hampers the accuracy of global land carbon-climate feedback projections7,8. Here we synthesize 136 datasets from 56 open-top chamber in situ warming experiments located at 28 arctic and alpine tundra sites which have been running for less than 1 year up to 25 years. We show that a mean rise of 1.4 °C [confidence interval (CI) 0.9-2.0 °C] in air and 0.4 °C [CI 0.2-0.7 °C] in soil temperature results in an increase in growing season ecosystem respiration by 30% [CI 22-38%] (n = 136). Our findings indicate that the stimulation of ecosystem respiration was due to increases in both plant-related and microbial respiration (n = 9) and continued for at least 25 years (n = 136). The magnitude of the warming effects on respiration was driven by variation in warming-induced changes in local soil conditions, that is, changes in total nitrogen concentration and pH and by context-dependent spatial variation in these conditions, in particular total nitrogen concentration and the carbon:nitrogen ratio. Tundra sites with stronger nitrogen limitations and sites in which warming had stimulated plant and microbial nutrient turnover seemed particularly sensitive in their respiration response to warming. The results highlight the importance of local soil conditions and warming-induced changes therein for future climatic impacts on respiration.

Epilepsy syndromes in patients with childhood-onset seizures in Finland.

Childhood-onset epilepsy is a common disorder. There is insufficient data on the distribution of epilepsy syndromes in the population and their effect on long-term prognosis. This report presents the data on epilepsy syndromes in a childhood-onset epilepsy cohort. A population-based active-prevalence cohort of all children under 16 years of age residing in the catchment area of Turku University Hospital with active epilepsy between 1961 and 1964 was monitored prospectively until 1992. Etiology, seizure type, and epilepsy syndromes were classified according to the recent guidelines of the International League Against Epilepsy. The etiology of seizures was idiopathic in 28%, cryptogenic in 22%, and remote symptomatic in 50%. Seizures were classifiable in 235 patients (96%) and included 157 (64%) with partial seizures and 88 (36%) with generalized seizures. Epilepsy syndromes could be classified in 223 patients (91%) and included 152 (62%) localization-related syndromes, 61 (25%) generalized epilepsy syndromes, and 10 (4%) with syndromes not determined as being focal or generalized. Prognosis for both survival and remission was dependent on etiology and on the specific epilepsy syndrome. The authors conclude that the International League Against Epilepsy guidelines can be successfully applied to a population-based cohort with childhood-onset epilepsy. Accurate classification of syndromes is important because in many cases long-term outcome may be largely determined by the underlying epilepsy syndrome.

Long-term prognosis of seizures with onset in childhood.

BACKGROUND: The long-term prognosis of seizures that begin in childhood is uncertain. METHODS: We prospectively studied 245 children from the catchment area of Turku University Hospital in Turku, Finland, who had active epilepsy diagnosed between 1961 and 1964. Sixty-eight patients (28 percent) had idiopathic seizures (presumed to have a genetic origin), 54 (22 percent) had cryptogenic seizures (occurring in otherwise normal persons with no clear cause), and 123 (50 percent) had remote symptomatic seizures (with no immediate cause but occurring in persons with a prior brain injury or a static encephalopathy). RESULTS: At the final follow-up in 1992, we had sufficient data on 220 patients (90 percent), 176 of whom were alive and 44 of whom had died; the remaining 25 had emigrated, could not be traced, or declined to participate. Thirty-nine patients who died were not free of seizures at the time of death, and 33 had remote symptomatic seizures. Among the surviving patients, 112 (64 percent) had been seizure-free for at least five years, including 83 (47 percent) who were not taking antiepileptic medications. The most important predictors of being seizure-free for at least five years were a rapid response to therapy (defined as a reduction in the frequency of seizures of 75 to 100 percent within three months of beginning treatment) and a diagnosis of idiopathic seizures. As compared with a matched control group, 99 patients with epilepsy but no other initial neurologic impairment were of similar socioeconomic status and had similar rates of passing an examination given after 12 years of school. Significantly more patients, however, had completed only six years of school (relative risk, 2.13), were unemployed (relative risk, 3.76), were not married (relative risk, 3.50), and did not have children (relative risk, 3.00). CONCLUSIONS: Although the majority of patients with epilepsy in childhood are free of seizures by the time they become adults, they are at increased risk for social and educational problems. Patients whose epilepsy does not remit also have an increased risk of death.

Social adjustment and competence 35 years after onset of childhood epilepsy: a prospective controlled study.

PURPOSE: To study the effect of childhood-onset epilepsy without other neurologic deficit on adult social adjustment and competence. METHODS: Social competence was studied in a prospective, population-based cohort of childhood-onset epilepsy after a mean follow-up of 35 years. One hundred patients (60% of the total cohort) had no other neurologic problems ("epilepsy only"), and for each patient, two matched controls, a "random" control and an "employee" control were chosen. RESULTS: Good social outcome was significantly reduced in the "epilepsy only" cohort compared with random controls: education [cumulative odds ratio (COR), 2.4; 95% confidence interval (CI), 1.4-4.1]; employability (COR, 7.3; 95% CI, 2.7-20.0); and marriage rate (COR, 3.7; 95% CI, 1.9-7.3). The patients with epilepsy rated their own ability to control their lives as "poor or missing" four times more frequently than the employee controls. Patients receiving antiepileptic polytherapy, but not monotherapy, were significantly less satisfied with their present life (OR, 6.7; 95% CI, 1.9-24.1) and felt their general health was significantly poorer (OR, 5.1; 95% CI, 1.2-21.3) than did the employee controls. Furthermore, patients with continuing seizures were significantly less satisfied with their present life (OR, 4.1; 95% CI, 1.1-15.1) than were employee controls. CONCLUSIONS: Many patients with "epilepsy only" beginning in childhood have persistent and significant social-adjustment and competence problems in adulthood.

Reproductive activity and offspring health of young adults with childhood-onset epilepsy: a controlled study.

PURPOSE: To study reproductive activity and offspring health in a prospective follow-up setting. METHODS: After a 35-year follow-up of a population-based patient cohort with childhood-onset "epilepsy only," 100 (56.8%) of 176 surviving patients were shown to have "epilepsy only", i.e., recurrent unprovoked seizures with no associated neuroimpairment. Their reproductivity and offspring health were compared with those of matched controls. RESULTS: The marriage rate and fertility of patients with "epilepsy only" were significantly reduced as compared with those of matched controls. Continuation of antiepileptic drug (AED) treatment was significantly associated with reduced reproduction, whereas occurrence of seizures during the previous 5 years was not. The incidence of epilepsy was nine times greater among the children of patients than among those of controls. No higher risks were observed in pregnancy or delivery in patients, nor were increased rates of birth defects in their offspring than in those of controls. Exposure to AEDs during pregnancy did not increase these risks. CONCLUSIONS: Patients with "epilepsy only" since childhood have fewer marriages and fewer children than expected. However, when they marry, their pregnancies and deliveries are unremarkable and their children do not have increased congenital health problems. Obviously, etiologies causative of both epilepsy and associated neurological impairments are more harmful to the course of pregnancy and delivery and offspring health than are those resulting in "epilepsy only".

Physical activity, health-related fitness, and health experience in adults with childhood-onset epilepsy: a controlled study.

PURPOSE: To show any possible associations between childhood-onset epilepsy and physical activity, health-related fitness, and health experience. METHODS: A population-based cohort of 176 patients with epilepsy since childhood was monitored for a mean of 35 years. Patients with recurrent, unprovoked epileptic seizures with no associated initial neurologic impairment or disability, termed those with "epilepsy only" (n = 100), were compared with matched controls for self-reported physical activity, health experience, laboratory tests, body mass index, and muscle power tests. RESULTS: On the basis of muscle tests, physical fitness proved to be significantly poorer in patients with "epilepsy only" than in matched controls. During the preceding year, 22% of patients and 24% of controls had reduced their physical activities because of some illness; only 2% reduced their physical activities because of epilepsy. No significant difference was found in blood status, except for a lower serum creatinine level in the patients. Current antiepileptic drug (AED) therapy appeared significantly associated with lower hemoglobin and creatinine levels and higher high-density lipoprotein values. The patients perceived their health status to be comparable with that of controls, irrespective of physical inactivity, continued seizures, or AED monotherapy. However, patients receiving AED polytherapy perceived their health as rather poor or very poor significantly more often than did controls. CONCLUSIONS: Based on objective muscle tests, adults with childhood-onset "epilepsy only" have poorer physical fitness than do matched controls, but they have a feeling of good personal health.

Concurrent illnesses in adults with childhood-onset epilepsy: a population-based 35-year follow-up study.

PURPOSE: To ascertain the occurrence of concurrent illnesses in adults with epilepsy since childhood. METHOD: After a mean follow-up of 35 years of a prospective, population-based long-term followed patient cohort with epilepsy since childhood, comorbidity was examined in 176 surviving (100 of them with epilepsy only) and 44 dead patients and in random and employee controls. RESULTS: Somatic comorbidity varied from 84 to 95% in patients and from 67 to 74% in controls. No significantly increased risk of somatic diseases could be shown. Psychosomatic disorders were associated in 46-74% of patients and in 42-75% of controls, and psychiatric disorders were associated in 11-23% of patients and in 7% of controls. As compared with random controls, patients with epilepsy had only a 4.0- to 4.2-fold risk of psychiatric disorders or of combinations of somatic, psychosomatic, and/or psychiatric disorders. Patients received psychotropic drugs 8.6 times more frequently than employee controls. The risk for psychiatric and psychosomatic disorders was higher than expected in patients with childhood-onset epilepsy, regardless of whether or not they were still receiving antiepileptic drugs (AEDs). CONCLUSION: Epilepsy per se, but not AEDs, has an apparent association with the occurrence of psychiatric and psychosomatic disorders. Risk for somatic comorbidity is not increased.

Single oral doses of amisulpride do not enhance the effects of alcohol on the performance and memory of healthy subjects.

OBJECTIVES: Amisulpride is a benzamide antipsychotic that binds selectively to dopamine D2- and D3-receptors, preferentially in limbic and hippocampal structures. Since other substituted benzamides have a limited or negligible interaction with alcohol on human performance, amisulpride was studied for this potential. METHODS: In a randomised double-blind crossover study, 18 young, non-smoking men took single oral doses of placebo and amisulpride 50 mg and 200 mg, without and with ethanol (0.8 g. kg-1) taken 30 min later. Objective performance tests and self-ratings were done at baseline and 1.5, 3.5 and 6.5 h after drug intake. Memory (immediate and delayed recall) was tested 2 h after dosing. Breath ethanol and the plasma concentrations of amisulpride and prolactin were measured. Three-way ANOVA + Newman-Keul tests were used for statistical analyses; interactions were confirmed by factorial contrast ANOVA. RESULTS: Mean blood ethanol was 0.94, 0.62 and 0.26 g.1(-1) at the three test times. It produced significant impairment in all performance tests (symbol digit substitution, simulated driving, body sway, flicker fusion, tapping, nystagmus), reduced both immediate and delayed recall in memory tests, and caused subjective clumsiness, muzziness and mental slowness, mainly between 1.5 to 4.5 h after dosing. Amisulpride, 50 and 200 mg elevated plasma prolactin but had minimal or no effect on performance, attention and memory. The decreases in immediate free recall after the 50 mg dose and in delayed free recall after the 200 mg dose were slight. Amisulpride neither modified blood ethanol concentrations nor enhanced the detrimental effect of ethanol on skilled and cognitive performance; it slightly antagonised ethanol in the digit copying test. Ethanol did not modify the effect of amisulpride on plasma prolactin, and the plasma concentrations of amisulpride were little changed by ethanol. CONCLUSIONS: Amisulpride in single oral doses of 50 and 200 mg did not interact significantly with the effects of high, moderate or low concentrations of ethanol on human skilled and cognitive performance. The drugs did interact pharmacokinetically.

Role of occupational exposure to airway irritants in the development of asthma.

In order to study the role of occupational exposure in the etiology of asthma, 78 asthmatics and 56 nonasthmatics from the Finnish twin cohort were investigated by means of a postal questionnaire. Among those studied were 31 identical twin pairs discordant with regard to asthma (i.e., only one member of the pair had asthma). The questionnaire inquired into the diagnosis and status of the asthma, smoking habits, atopic background, smoking history of the parents, and history as regards pets, and requested a detailed description of occupational exposure to airway allergens and irritants. Classification into asthmatics and nonasthmatics was based on the information gathered with the questionnaire, supplemented by other information whenever possible. Estimation of exposure was based on the subject's own report, on the work descriptions, and on the general knowledge about the exposure levels associated with work tasks in question. Exposure to organic solvents was found only in the asthmatic members of the discordant pairs, and none of the nonasthmatic persons had been exposed to solvents. There were no statistically significant differences as regards exposure to other unspecific irritants. Combined exposure to organic allergens and airway irritants was more common in the asthmatics than in the nonasthmatics (P = 0.009). Exposure to irritants was also more common among the asthmatics than the nonasthmatics with similar exposure to organic allergens (P = 0.004).