Electroencephalographic functional connectivity is altered in persons with Down syndrome and Alzheimer's disease.

BACKGROUND: Persons with Down syndrome (DS) are at increased risk of developing Alzheimer's dementia (DS-AD). Due to heterogeneity in the functioning in persons with DS, it is difficult to use cognitive testing to assess whether a person with DS has developed dementia due to AD. Electroencephalography (EEG) functional connectivity has shown promising results as a diagnostic tool for AD in persons without DS. In the current exploratory study, we investigated whether EEG functional connectivity could be used as a diagnostic marker of AD in persons with DS and the association with symptoms. METHODS: Electroencephalography from 12 persons with DS and 16 persons with DS-AD were analysed, and both coherence and weighted phase lag index were calculated. In addition, we calculated the average coherence for fronto-parietal and temporo-parietal connections. Lastly, we investigated the correlation between the informant-based Dementia Screening Questionnaire in Intellectual Disability (DSQIID) and total alpha coherence. RESULTS: Decreased alpha and increased delta coherence and weighted phase lag index were observed in DS-AD as compared with DS. The decrease in alpha coherence was more marked in the fronto-parietal connections as compared with the temporo-parietal connections. No significant correlation was found between DSQIID and total alpha coherence (P value = 0.095, rho = -0.335). CONCLUSION: The decreased alpha coherence and weighted phase lag index have previously been found in AD. The increased delta coherence and weighted phase lag index may indicate a different initial neurophysiological presentation as compared with patients with AD or may be a sign of more advanced disease. Larger studies are needed to confirm the current findings.

Time preferences, diabetes self-management behaviours and outcomes: a systematic review.

AIM: Time preferences, i.e. individuals' degree of patience/impatience in intertemporal choice, have been found to be associated with suboptimal health behaviours and health outcomes such as smoking, physical inactivity, unhealthy food intake and obesity. In this systematic review, we aimed to synthesise reported associations between time preferences, diabetes self-management behaviours, including use of diabetes technology, and outcomes. METHODS: We searched MEDLINE, EMBASE, PsycINFO, CINAHL, EconLit and all databases in the Web of Science Core Collection. Peer-reviewed studies of people with diabetes that included at least one diabetes-related behaviour or outcome and a measure of time preferences were included. Non-English language studies were excluded. RESULTS: A total of 961 records were identified, of which 12 articles were included. Three studies analysed both time-consistent and time-inconsistent preferences, three studies solely analysed time-inconsistent preferences and six studies did not explicitly define a time preference model. Measured outcomes across studies included self-care activities, such as medication-taking, exercising and eating a healthy diet, and biomedical outcomes, such as HbA1c and diabetes-related complications. There were 10 cross-sectional studies and two panel-data studies. No studies explicitly analysed the relationship between time preferences and diabetes technology use. CONCLUSIONS: Associations between measures of time preferences, diabetes self-management behaviours and clinical outcomes exist. Higher discount rates determined by both time-consistent and time-inconsistent models predict less diabetes-related self-care and worse outcomes. These findings may add to explanations of the observed variation in diabetes-related health and provide new insights for tailoring interventions and policies aimed at improving diabetes self-management.

Associations between electroencephalography power and Alzheimer's disease in persons with Down syndrome.

BACKGROUND: It is complicated to diagnose dementia in persons with Down syndrome (DS). Older studies have, however, demonstrated low-frequency activity in electroencephalography (EEG) in persons with concurrent DS and Alzheimer's disease (DS-AD). The aim of this study was to examine whether it was possible to identify AD-associated changes (increased high-frequency power and decreased low-frequency power) in persons with DS-AD compared with DS. METHODS: We included 21 persons with DS-AD and 16 with DS without cognitive deterioration assessed by the informant-based Dementia Screening Questionnaire in Intellectual Disability. EEG was recorded for all participants. Absolute power for each electrode and global power were calculated for all frequency bands for both eyes open and eyes closed. RESULTS: For global power in the eyes closed condition, we found an increased global slow-frequency activity and a decreased global high-frequency activity in DS-AD compared with DS. In addition, we found a significant difference in the global alpha/delta ratio with the largest difference found for global alpha power in DS-AD compared with DS. CONCLUSIONS: In the current study, we found that changes known to be associated with AD could also be identified when comparing DS-AD with DS using quantitative EEG. In general, these findings suggest that EEG might be a useful tool in diagnosing AD in persons with DS, but larger studies are needed.

Circulating sCD36 levels in patients with non-alcoholic fatty liver disease and controls.

BACKGROUND AND OBJECTIVE: CD36 is implicated in fatty-acid uptake in multiple tissues, including hepatocytes and adipocytes. Circulating CD36 (sCD36) is increased in non-alcoholic fatty liver disease (NAFLD). We explored this association further by investigating correlations between sCD36 levels, intrahepatic lipid content and markers of obesity in NAFLD patients and controls. METHODS: In total, 111 NAFLD patients and 33 normal/overweight controls were included. Intrahepatic lipid content was measured by magnetic resonance spectroscopy; and subgroups of participants had a dual-energy X-ray absorptiometry (n=99), magnetic resonance imaging (n=94, subcutaneous and visceral adipose tissue) and liver biopsy (n=28 NAFLD patients) performed. Plasma sCD36 was assessed by enzyme-linked immunosorbent assay. RESULTS: NAFLD patients had elevated sCD36 levels compared with controls (0.68 (0.12-2.27) versus 0.43 (0.10-1.18), P<0.01). sCD36 correlated with intrahepatic lipid (rs=0.30), alanine transaminase (ALT) (r=0.31), homeostasis model assessment index-insulin resistance (r=0.24), high-density lipoprotein (r=-0.32) and triglyceride (r=0.44, all P<0.01). Intrahepatic lipid and plasma triglyceride were independent predictors of sCD36 levels in a multiple regression analysis. Further, sCD36 and body mass index were weakly correlated (r=0.17, P=0.04); yet, we found no correlations between sCD36 and other measures of fat distribution except an inverse relation to visceral adipose tissue (rs=-0.21, P<0.05). We observed a trend for correlation between sCD36 and hepatic CD36 mRNA expression (r=0.37, P=0.07). CONCLUSIONS: sCD36 levels increased with the level of intrahepatic lipid, insulin resistance and dyslipidemia. The weak association with markers of obesity and the association with hepatic CD36 mRNA expression suggest that excess sCD36 in NAFLD patients is derived from the hepatocytes, which may support that CD36 is involved in NAFLD development. An unhealthy and unbalanced CD36 expression in adipose and hepatic tissue may shift the fatty-acid load to the liver.

Drug taper during long-term video-EEG monitoring: efficiency and safety.

OBJECTIVES: Anti-epileptic drugs (AED) are often tapered to reduce the time needed to record a sufficient number of seizure during long-term video-EEG monitoring (LTM). Fast AED reduction is considered less safe, but few studies have examined this. Our goal is to examine whether the rate of AED reduction affects efficiency and safety. MATERIALS & METHODS: We performed a retrospective observational study of patients referred for presurgical evaluation. Each patient was categorized by two dichotomous parameters of AED tapering: (i) fast vs slow AED reduction the first 24 h of LTM and (ii) complete vs partial AED discontinuation during LTM. RESULTS: Of 79 patients, 51% underwent a fast AED reduction and 58% ended up with AEDs completely discontinued. Complete AED discontinuation was associated with three times increased likelihood of receiving rescue therapy during LTM and double risk of having secondary generalized tonic-clonic seizures (sGTCS) compared to the group partially discontinued. Fast vs slow AED reduction had no effect on the safety of LTM. The fast AED reduction group and the complete AED discontinuation group had a significantly longer time to first seizure and total recording time compared to the slow AED reduction and partial discontinuation groups, respectively. CONCLUSIONS: Fast AED reduction was found safe in patients undergoing presurgical video-EEG monitoring. Patients completely discontinued from AEDs had more sGTCS than patients partially discontinued. Further studies are suggested to confirm this finding and to evaluate whether fast reduction is safe and efficient in other subgroups of patients referred for LTM.

Oligomerization of Mannan-binding Lectin Dictates Binding Properties and Complement Activation.

The complement system is a part of the innate immune system and is involved in recognition and clearance of pathogens and altered-self structures. The lectin pathway of the complement system is initiated when soluble pattern recognition molecules (PRMs) with collagen-like regions bind to foreign or altered self-surfaces. Associated with the collagen-like stems of these PRMs are three mannan-binding lectin (MBL)-associated serine proteases (MASPs) and two MBL-associated proteins (MAps). The most studied of the PRMs, MBL, is present in serum mainly as trimeric and tetrameric oligomers of the structural subunit. We hypothesized that oligomerization of MBL may influence both the potential to bind to micro organisms and the interaction with the MASPs and MAps, thus influencing the ability to initiate complement activation. When testing binding at 37 °C, we found higher binding of tetrameric MBL to Staphylococcus aureus (S. aureus) than trimeric and dimeric MBL. In serum, we found that tetrameric MBL was the main oligomeric form present in complexes with the MASPs and MAp44. Such preference was confirmed using purified forms of recombinant MBL (rMBL) oligomers, where tetrameric rMBL interacted stronger with all of the MASPs and MAp44, compared to trimeric MBL. As a direct consequence of the weaker interaction with the MASPs, we found that trimeric rMBL was inferior to tetrameric rMBL in activating the complement system. Our data suggest that the oligomeric state of MBL is crucial both for the binding properties and the effector function of MBL.

Socioeconomic position and survival after cervical cancer: influence of cancer stage, comorbidity and smoking among Danish women diagnosed between 2005 and 2010.

BACKGROUND: In an attempt to decrease social disparities in cancer survival, it is important to consider the mechanisms by which socioeconomic position influences cancer prognosis. We aimed to investigate whether any associations between socioeconomic factors and survival after cervical cancer could be explained by socioeconomic differences in cancer stage, comorbidity, lifestyle factors or treatment. METHODS: We identified 1961 cases of cervical cancer diagnosed between 2005 and 2010 in the Danish Gynaecological Cancer database, with information on prognostic factors, treatment and lifestyle. Age, vital status, comorbidity and socioeconomic data were obtained from nationwide administrative registers. Associations between socioeconomic indicators (education, income and cohabitation status) and mortality by all causes were analysed in Cox regression models with inclusion of possible mediators. Median follow-up time was 3.0 years (0.01-7.0). RESULTS: All cause mortality was higher in women with shorter rather than longer education (hazard ratio (HR), 1.46; 1.20-1.77), among those with lower rather than higher income (HR, 1.32; 1.07-1.63) and among women aged<60 years without a partner rather than those who cohabited (HR, 1.60; 1.29-1.98). Socioeconomic differences in survival were partly explained by cancer stage and less by comorbidity or smoking (stage- and comorbidity-adjusted HRs being 1.07; 0.96-1.19 for education and 1.15; 0.86-1.52 for income). CONCLUSION: Socioeconomic disparities in survival after cervical cancer were partly explained by socioeconomic differences in cancer stage. The results point to the importance of further investigations into reducing diagnosis delay among disadvantaged groups.

Psychiatric disorders in women with fertility problems: results from a large Danish register-based cohort study.

STUDY QUESTION: Do women who don't succeed in giving birth after an infertility evaluation have a higher risk of psychiatric disorders compared with women who do? SUMMARY ANSWER: The results indicated that being unsuccessful in giving birth after an infertility evaluation could be an important risk factor for psychiatric disorders. WHAT IS KNOWN ALREADY: Several studies have investigated the association between fertility treatment and psychological distress, but the results from these studies show substantial variation and lack of homogeneity that may be due to methodological limitations. STUDY DESIGN, SIZE AND DURATION: A retrospective cohort study was designed using data from a cohort of 98 320 Danish women evaluated for fertility problems during 1973-2008 and linked to several Danish population-based registries. All women were followed from the date of first infertility evaluation until date of hospitalization for the psychiatric disorder in question, date of emigration, date of death or 31 December 2008, whichever occurred first. Owing to the precise linkage between the infertility cohort and the Danish population-based registries, using the unique Danish personal identification number, virtually no women were lost to follow-up. PARTICIPANTS/MATERIALS, SETTING AND METHODS: Information on reproductive status for all women in the infertility cohort was obtained by linkage to the Danish Medical Birth Registry. A total of 53 547 (54.5%) women gave birth after the initial infertility evaluation, whereas 44 773 (45.5%) women did not gave birth after the evaluation. To determine psychiatric disorders diagnosed in the women after enrolment in the infertility cohort, the cohort was linked to the Danish Psychiatric Central Registry. A total of 4633 women were hospitalized for a psychiatric disorder. The Cox proportional hazard regression model was applied to estimate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) for the association between parity status after the initial infertility evaluation and risk of hospitalization for various groups of psychiatric disorders, including 'all mental disorders' and six main discharge subgroups labelled: 'alcohol and intoxicant abuse', 'schizophrenia and psychoses', 'affective disorders', 'anxiety, adjustment and obsessive compulsive disorders', 'eating disorder' and 'other mental disorders'. MAIN RESULTS AND THE ROLE OF CHANCE: The incidence rate for all mental disorders was 393 cases per 100 000 person-years among women who did not succeed in giving birth after the infertility evaluation but only 353 cases per 100 000 person-years among women who succeeded in giving birth after the infertility evaluation. Women not giving birth after the infertility evaluation had an increased risk of hospitalization for all mental disorders (HR 1.17, 95% CI 1.11; 1.25), alcohol and intoxicant abuse (HR 2.02, 95% CI 1.69; 2.41), schizophrenia and psychoses (HR 1.46, 95% CI 1.17; 1.82) and other mental disorders (HR 1.42, 95% CI 1.27; 1.58) compared with women who gave birth after the infertility evaluation. In contrast, the risk of affective disorders (HR 0.90, 95% CI 0.81; 0.99) was decreased among women not giving birth after the infertility evaluation. Finally, the risk of anxiety, adjustment and obsessive compulsive disorders (HR 1.07, 95% CI 0.97; 1.17) as well as of eating disorders (HR 1.40, 95% CI 0.88; 2.22) was not significantly affected by parity status after the infertility evaluation. LIMITATIONS, REASON FOR CAUTION: As only psychiatric conditions warranting hospitalization could be included in the present study, the true incidence of all psychiatric disorders among women with fertility problems is likely to be somewhat underestimated. Furthermore, since detailed information on fertility treatment was not available for all cohort members the association between different modalities of assisted reproductive techniques and risk of psychiatric disorders was not assessed. WIDER IMPLICATIONS OF THE FINDINGS: Clinicians and other healthcare personnel involved in diagnosis and treatment of women with fertility problems should be aware of the potential risk modification of psychiatric disorders associated with unsuccessful fertility treatment. Hence, our results may point to new aspects of follow-up of women with fertility problems who are unsuccessful in giving birth in order to prevent or identify and treat these possible psychological side effects. STUDY FUNDING/COMPETING INTEREST(S): The study was supported by the Danish Cancer Society (award number: 96 222 54). All authors report no conflicts of interest.

Scope insensitivity in contingent valuation studies of health care services: should we ask twice?

The main purpose of the present study was to test for outcome scope insensitivity. Respondents were initially asked to value one of two severe health states by way of a time-trade-off (TTO) exercise. Subsequent to the TTO exercise all respondents were asked to value an intervention, which offered a reduction in risk of falling into the health state they had evaluated. All respondents were subsequent to this initial CV exercise asked to value the same risk reduction, but in this case the outcome was death. Although our study passes the internal scope test, there is not a high degree of sensitivity to outcome. As many as 68% of respondents stated an identical maximum WTP in first and second CV valuation exercise implying that they value the interventions equally despite the fact that the health state presented in the initial CV question was deemed far better than death according to the TTO responses given by the same respondents. In contrast, the external scope test (comparison of response to initial CV across study arms) fared much better.

Intraoperative hyperventilation vs remifentanil during electrocorticography for epilepsy surgery - a case report.

BACKGROUND: Traditionally, intraoperative intracranial electroen-cephalography-recordings are limited to the detection of the irritative zone defined by interictal spikes. However, seizure patterns revealing the seizure onset zone are thought to give better localizing information, but are impractical due to the waiting time for spontaneous seizures. Therefore, provocation by seizure precipitants may be used with the precaution that spontaneous and provoked seizures may not be identical. OBJECTIVE: We present evidence that hyperventilation induced and drug induced focal seizures may arise from different brain regions in the same patient. METHODS: Hyperventilation and ultra short acting opioid remifentanil were used separately as intraoperative precipitatants of seizure patterns, while recording from subdural and intraventricular electrodes in a patient with temporal lobe epilepsy. Two different ictal onset zones appeared in response to hyperventilation and remifentanil. Both zones were resected and the patient has remained essentially seizure free for 1 year. Furthermore, this is the first description of hyperventilation used as an intraoperative seizure precipitant in human focal epilepsy.

Cancer incidence among male Danish nurses, 1980-2003.

BACKGROUND: The cancer risk of female nurses has been examined in several studies, but none has addressed the risk of male nurses, although they may be exposed to the same carcinogens as female nurses. In this register-based cohort study, we explored cancer incidence among male Danish nurses. METHODS: We identified 3369 male nurses from the files of the Danish Nurses Association and followed them up from 1980 to 2003 in the Danish Cancer Registry. Standardized incidence ratios (SIRs) and 95% confidence intervals were calculated on the basis of standardized national rates. We compared the nurses with 3369 other male employees matched to the nurses by year of birth on social variables (vital and marital status). FINDINGS: We observed 90 cancers in the cohort, with significantly increased SIRs for sarcomas and decreased SIRs for cancers of the respiratory system. When the cohort was stratified by educational generation and birth cohort, we observed significantly elevated relative risks for cancers of the brain and nervous system among the youngest nurses and for sarcomas among nurses in all educational generations and those born between 1945 and 1954. CONCLUSION: The overall risk for cancer among male Danish registered nurses is similar to that of the general male Danish population. The high SIRs observed for cancers of the brain and nervous system merit further attention. The high relative risks for sarcomas and connective tissue tumours reflect a large proportion of cases of Kaposi sarcoma, which is probably not occupationally related.

Remifentanil-induced spike activity as a diagnostic tool in epilepsy surgery.

OBJECTIVES: To assess the value of remifentanil in intraoperative evaluation of spike activity in patients undergoing surgery for mesial temporal lobe epilepsy (MTLE). MATERIALS AND METHODS: Twenty-five patients undergoing temporal lobectomy for medically intractable MTLE were enrolled in the study. Electrocorticography (ECoG) recordings were performed on the intraventricular hippocampus and from the anterior inferior temporal and lateral neocortex before and after a 300 microg intravenous bolus of remifentanil. Spike activity was quantified as spike-count per minute. RESULTS: A significant increase (P < 0.005) in spike activity was observed after administration of remifentanil in 23 of 25 patients (92%). Furthermore, two patients who did not have any spike activity on the baseline ECoG developed spikes after administration of remifentanil. CONCLUSIONS: The results suggest that remifentanil can enhance spike activity in the epileptogenic zone and reveal otherwise concealed epileptogenic tissue in patients with MTLE. Thus, remifentanil may prove to be an important diagnostic tool during surgical treatment for intractable focal epilepsy.

Detection of generalized tonic-clonic seizures from ear-EEG based on EMG analysis.

PURPOSE: Sudden unexpected death in epilepsy (SUDEP) is associated with generalized tonic-clonic seizures (GTCS) with most deaths occurring during sleep. Seizure detection devices have been suggested as a SUDEP prevention strategy. EMG-based GTCS detection can take advantage of the GTCS characteristic of sustained high-amplitude, high-frequency activity in the time-domain. METHOD: We present a GTCS-detection method based on median-filtered variance estimates on surface EMG measurements and describe its performance in a small exploratory proof-of-concept setting involving a group of 15 patients with 3 GTCS recorded with ear-EEG and another group of 6 patients with 11 GTCS recorded with scalp-EEG. RESULTS: GTCS intervals were detected within 4.2-12.9 s of onset with 100% sensitivity (CI 29.2-100%) without false positives in 820.7 h of ear-EEG. The same detection method worked for the 11 GTCS from scalp EEG data with 100% sensitivity (CI 71.5-100%) and no false positives. CONCLUSIONS: Ear-EEG contains enough GTCS-specific EMG activity for GTCS detection to be feasible. Ear-EEG could be considered for nocturnal GTCS monitoring as a supplement to SUDEP preventive interventions.

Comparison of bone turnover markers in peripheral blood and bone marrow aspirate.

BACKGROUND: Bone remodeling takes place in the bone marrow environment. We investigated if levels of bone turnover markers (BTMs) differ between bone marrow and peripheral blood, if the bone marrow is an independent compartment, and how well the measurements in bone marrow correlate with bone mineral density. METHODS: Sixty-six men participated in a placebo controlled study designed to evaluate the effect of 16 weeks supplementation with resveratrol on bone mineral density and BTM. Bone marrow aspirates and blood samples were drawn at baseline and at week 16. Procollagen I N-terminal propeptide (PINP), C-terminal telopeptide of type I collagen (CTx), osteocalcin, bone specific alkaline phosphatase (BAP), and osteoprogeterin (OPG) were analyzed. Bland-Altman analysis was used to compare measurements across compartment to detect possible systematic or proportional differences. Paired t-test was performed if no proportional difference was revealed at the difference vs concentration plot. RESULTS: Measurements of PINP, CTx, and BAP differed proportionally between compartments depending on concentration; at low concentrations absolute values were only slightly different, while at higher average concentrations the levels were much higher in bone marrow than blood. Osteocalcin measures in bone marrow were systematically and significantly lower than in blood (mean ±â€¯SD; 14.4 µg/L ±â€¯5.3 µg/L versus 21.7 µg/L ±â€¯6.0 µg/L respectively, p < 0.001). OPG measures were comparable between compartments (p = 0.69). CTx and OPG measured in blood were negatively associated with lumbar spine BMD (ß = -0.22, p = 0.05 and ß = -0.02, p = 0.02, respectively), whereas both markers measured in bone marrow were not (p = 0.60 and p = 0.50 respectively). None of the BTMs, bone marrow or blood, were associated with total hip BMD. DISCUSSION: The levels of most BTMs differed significantly between bone marrow and peripheral blood, while OPG was comparable. Levels of PINP, CTx, and BAP differed between compartments depending on concentration, suggesting bone marrow to represent a compartment separate from the general circulation. Unexpectedly, osteocalcin was lower in the marrow, a gradient that was independent of concentration. BTMs measured in bone marrow did not show any association with bone mineral density. Although further studies are needed to investigate potential explanatory causes of the differences, BTMs in bone marrow do not seem to contribute further to fracture risk assessment.

Shorter preschool, leukocyte telomere length is associated with obesity at age 9 in Latino children.

The aim of this study was to determine the potential role of leukocyte telomere length as a biomarker for development of childhood obesity in a low-income Latino population. A birth cohort of Latino children (N = 201) in San Francisco (recruited May 2006-May 2007) was followed until age 9 and assessed annually for obesity and dietary intake. Leukocyte telomere length was measured at 4 and 5 years (n = 102) and assessed as a predictor for obesity at age 9, adjusting for known risk factors. Furthermore, leukocyte telomere length at age 4 and 5 was evaluated as a possible mediator of the relationship between excessive sugar-sweetened beverage consumption and obesity at age 9. Shorter leukocyte telomere length in preschoolers was associated with obesity at age 9 (adjusted odds ratio 0.35, 95% confidence interval 0.13-0.94) after adjustment for known risk factors. Telomere length mediated 11% of the relationship between excessive sugar-sweetened beverage consumption and obesity. Shorter leukocyte telomere length may be an indicator of future obesity risk in high-risk populations as it is particularly sensitive to damage from oxidative stress exposure, including those from sugar-sweetened beverages.

Ear-EEG detects ictal and interictal abnormalities in focal and generalized epilepsy - A comparison with scalp EEG monitoring.

OBJECTIVE: Ear-EEG is recording of electroencephalography from a small device in the ear. This is the first study to compare ictal and interictal abnormalities recorded with ear-EEG and simultaneous scalp-EEG in an epilepsy monitoring unit. METHODS: We recorded and compared simultaneous ear-EEG and scalp-EEG from 15 patients with suspected temporal lobe epilepsy. EEGs were compared visually by independent neurophysiologists. Correlation and time-frequency analysis was used to quantify the similarity between ear and scalp electrodes. Spike-averages were used to assess similarity of interictal spikes. RESULTS: There were no differences in sensitivity or specificity for seizure detection. Mean correlation coefficient between ear-EEG and nearest scalp electrode was above 0.6 with a statistically significant decreasing trend with increasing distance away from the ear. Ictal morphology and frequency dynamics can be observed from visual inspection and time-frequency analysis. Spike averages derived from ear-EEG electrodes yield a recognizable spike appearance. CONCLUSIONS: Our results suggest that ear-EEG can reliably detect electroencephalographic patterns associated with focal temporal lobe seizures. Interictal spike morphology from sufficiently large temporal spike sources can be sampled using ear-EEG. SIGNIFICANCE: Ear-EEG is likely to become an important tool in clinical epilepsy monitoring and diagnosis.

Case comparison of sleep features from ear-EEG and scalp-EEG.

BACKGROUND: We investigate the potential usability of a novel in-the-ear electroencephalography recording device for sleep staging. METHODS: In one healthy subject we compare simultaneous earelectroencephalography to standard scalp EEG visually and using power spectrograms. Hypnograms independently derived from the records are compared. RESULTS: We find that alpha activity, K complexes, sleep spindles and slow wave sleep can be visually distinguished using earelectroencephalography. Spectral peaks are shared between the two records. Hypnograms are 90.9% similar. CONCLUSION: The results indicate that ear-electroencephalography can be used for sleep staging.

Abnormal structure and function of isolated subcutaneous resistance vessels from essential hypertensive patients despite antihypertensive treatment.

The morphological and functional characteristics of isolated subcutaneous resistance vessels (about 230 microns internal diameter) from 13 patients treated for essential hypertension for a median period of 14 months and from 15 matched normotensive controls were examined. The blood pressure of the patients and the controls were not significantly different at the time of examination. However, although compared with the controls, the lumen diameter of the vessels from the patients was not significantly different, the media thickness to lumen diameter ratio was 19% greater. Furthermore, although there was no difference in the active pressure response of the vessels from the two groups, the vessels from the patients had a lower sensitivity to calcium, relaxed faster after a contraction and the sensitivity to exogenous noradrenaline shifted more to the left with cocaine. Since the abnormalities found here have previously also been found in vessels from patients with untreated essential hypertension, the study suggests that despite antihypertensive treatment to normotensive levels for about 1 year, some morphological as well as functional characteristics of the resistance arteries are not fully normalized. This could have consequences for the prognosis of essential hypertension.

Biosensor determination of the microscale distribution of nitrate, nitrate assimilation, nitrification, and denitrification in a diatom-inhabited freshwater sediment

High-resolution NO3- profiles in freshwater sediment covered with benthic diatoms were obtained with a new microscale NO3- biosensor characterized by absence of interference from chemical species other than NO2- and N2O. Analysis of the microprofiles obtained indicated no nitrification during darkness, high rates of nitrification and a tight coupling between nitrification and denitrification during illumination, and substantial rates of NO3- assimilation during illumination. Nitrification during darkness could be induced by purging the bulk water with O2 gas, indicating that the stimulatory effect on nitrification by illumination was caused by algal production of O2. NH4+ addition did not stimulate nitrification during darkness when O2 was restricted to the upper 1-mm layer, and there was thus a low nitrification potential in the permanently oxic top 1 mm of the sediment.

Fluorescence-activated cell sorted rat islet cells and studies of the insulin secretory process.

Studies of individual cell types in the islets of Langerhans are complicated by the cells' functional coupling by gap junctions and paracrine interaction. Access to purified alpha and beta cells is therefore desirable. We present a simplified and optimized method for fluorescence-activated cell sorting of endocrine pancreatic rat islets. For dispersion of the islets, dispase was superior to trypsin, as the number of vital single cells was higher (1.1 +/- 0.1 x 10(3) vs 0.6 +/- 0.1 x 10(3)/islet, P < 0.05). The purity of the sorted cells was 96.7 +/- 1.2% for the non-beta cells and 97.8 +/- 0.6% for the beta cells (numbers in percentages of endocrine cells). In culture, isolated beta cells, non-beta cells and mixtures of beta and non-beta cells formed aggregates, but not at low temperature (4 degrees C) and not in medium with low serum content (2%). Finally, in pure beta cell aggregates, glucose stimulated changes in cytoplasmic free Ca2+ concentration although both glucose- and arginine-induced insulin secretion was much reduced. We conclude that alpha cells are necessary for insulin secretion but not for glucose sensing.