Gain-of-function mutation in Nav1.7 in familial erythromelalgia induces bursting of sensory neurons

Erythromelalgia is an autosomal dominant disorder characterized by burning pain in response to warm stimuli or moderate exercise. We describe a novel mutation in a family with erythromelalgia in SCN9A, the gene that encodes the Na(v)1.7 sodium channel. Na(v)1.7 produces threshold currents and is selectively expressed within sensory neurons including nociceptors. We demonstrate that this mutation, which produces a hyperpolarizing shift in activation and a depolarizing shift in steady-state inactivation, lowers thresholds for single action potentials and high frequency firing in dorsal root ganglion neurons. Erythromelalgia is the first inherited pain disorder in which it is possible to link a mutation with an abnormality in ion channel function and with altered firing of pain signalling neurons.

The incidence of acute brain injury and serious impairment in a defined population

Studies on the incidence and epidemiologic features of brain injury and the immediate medical outcomes are few, and published results have serious methodological inconsistencies which prohibit comparisons. This study provides incidence rates of brain injury among the residents of San Diego, California. Cases had clinical confirmation and onset of injury occurred during 1981. The 3358 cases identified represent a rate of 180/100,000 with males having a 2.2 times higher rate than females. Rates were highest for males aged 15-24 years and, for both genders, those over age 70. Forty-eight per cent of all cases were from transport-related causes, followed by falls (21%) and assaults (12%). Over 11% were dead-on-arrival, and 16% were classified as having moderate or severe brain damage on admission to a hospital. Age- and sex-specific incidence rates varied according to external cause of injury. For example, for most subcategories of motor vehicle crashes and for assaults, the incidence rate was highest among males aged 15-24, while for brain injuries from falls or firearms, highest incidence rates were observed in older age groups. Almost 7% of all cases discharged alive from an acute care hospital had significant neurologic sequelae. The impact of brain injury is discussed as a major unresolved public health problem.

Prolonged hypernatremia controls elevated intracranial pressure in head-injured pediatric patients

OBJECTIVE

To determine the effects continuous infusions of hypertonic saline (3% NaCl) on intracranial pressure (ICP) control and describe the physiologic effects of hypertonic saline administered to closed head injury children.

DESIGN

Retrospective chart review.

SETTINGS

Pediatric intensive care unit of a children's hospital.

PATIENTS

Sixty-eight children with closed head injury.

INTERVENTIONS

Intravenous infusion of 3% hypertonic saline to increase serum sodium to levels necessary to reduce ICP < or =20 mm Hg.

MEASUREMENTS AND MAIN RESULTS

The patients enrolled had similar Injury Severity Scores. Treatment effectively lowered ICP in these patients and ICP was under good control a majority of the time. Only three patients (4%) died of uncontrolled elevation of ICP. No adverse effects of supraphysiologic hyperosmolarity such as renal failure, pulmonary edema, or central pontine demyelination, were noted.

CONCLUSIONS

Hypertonic saline administration to children with closed head injury appears to be a promising therapy for control of cerebral edema. Further controlled trials are required to determine the optimal duration of treatment before widespread use is advocated.

Human aquaporins: regulators of transcellular water flow

BACKGROUND

Emerging evidence supports the view that (AQP) aquaporin water channels are regulators of transcellular water flow. Consistent with their expression in most tissues, AQPs are associated with diverse physiological and pathophysiological processes.

SCOPE OF REVIEW

AQP knockout studies suggest that the regulatory role of AQPs, rather than their action as passive channels, is their critical function. Transport through all AQPs occurs by a common passive mechanism, but their regulation and cellular distribution varies significantly depending on cell and tissue type; the role of AQPs in cell volume regulation (CVR) is particularly notable. This review examines the regulatory role of AQPs in transcellular water flow, especially in CVR. We focus on key systems of the human body, encompassing processes as diverse as urine concentration in the kidney to clearance of brain oedema.

MAJOR CONCLUSIONS

AQPs are crucial for the regulation of water homeostasis, providing selective pores for the rapid movement of water across diverse cell membranes and playing regulatory roles in CVR. Gating mechanisms have been proposed for human AQPs, but have only been reported for plant and microbial AQPs. Consequently, it is likely that the distribution and abundance of AQPs in a particular membrane is the determinant of membrane water permeability and a regulator of transcellular water flow.

GENERAL SIGNIFICANCE

Elucidating the mechanisms that regulate transcellular water flow will improve our understanding of the human body in health and disease. The central role of specific AQPs in regulating water homeostasis will provide routes to a range of novel therapies. This article is part of a Special Issue entitled Aquaporins.

Insecticidal proteins from Bacillus thuringiensis protect corn from corn rootworms

Field tests of corn co-expressing two new delta-endotoxins from Bacillus thuringiensis (Bt) have demonstrated protection from root damage by western corn rootworm (Diabrotica virgifera virgifera LeConte). The level of protection exceeds that provided by chemical insecticides. In the bacterium, these proteins form crystals during the sporulation phase of the growth cycle, are encoded by a single operon, and have molecular masses of 14 kDa and 44 kDa. Corn rootworm larvae fed on corn roots expressing the proteins showed histopathological symptoms in the midgut epithelium.

EEG complexity and performance measures of creative thinking

The electroencephalogram (EEG) was used because of its dimensional complexity to establish a differentiation of divergent versus convergent thought, considered fundamental modes of cortical processing. In 28 men, the EEG was recorded while solving tasks of divergent and convergent thinking and during mental relaxation. The EEG during divergent thought was compared between subjects achieving high versus low performance scores on this type of task. The dimensional complexity of the EEG was greater during divergent thinking than during convergent thinking. While solving tasks of divergent thinking, subjects with high performance scores had a lower EEG dimension than did subjects with low scores, in particular over frontal cortical areas. The changes were not reflected in single frequency bands of conventional EEG analysis. Based on Hebb's view of neuron assemblies as functional processing units, the higher EEG complexity during divergent than convergent thinking could be the result of the concurrent activation of a greater number of independently oscillating processing units.

Acute effects of recombinant human interleukin-6 on endocrine and central nervous sleep functions in healthy men

Interleukin-6 (IL-6) is a proinflammatory cytokine that has been shown to mediate, in addition to immune reactions, various endocrine and central nervous components of the acute phase response. In this context, the present study aimed to specify the contributions of IL-6 to the regulation of pituitary-adrenal secretory activity and GH and TSH secretion, as well as to the regulation of central nervous sleep and mood in healthy men. Effects of a low dose of IL-6 (0.5 microgram/kg body weight) were assessed, inducing plasma IL-6 concentrations closely comparable with those typically observed after infectious challenge. Each of the 16 male subjects participated in two 14-h sessions (between 1800 and 0800 h), receiving either placebo or human recombinant IL-6 sc at 1900 h. Blood was collected repeatedly to determine plasma hormone levels, serum concentrations of cytokines, and C-reactive protein. Moreover, mood was assessed, and sleep recordings were obtained between 2300 and 0700 h. The cytokine induced a prolonged increased in plasma concentrations of ACTH and cortisol (P < 0.001), but led to a decrease in TSH concentrations (P < 0.01). In response to IL-6, subjects reported fatigue and felt more inactive and less capable of concentrating than after placebo. Sleep architecture was altered significantly by the cytokine. Slow-wave sleep was decreased during the first half and increased during the second half of sleep. Rapid eye movement sleep during the entire nocturnal sleep time was significantly decreased. After IL-6, body temperature rose slightly. C-reactive protein concentrations were dramatically increased 12.5 h after substance administration (P < 0.001). IL-6 did not affect serum concentrations of IL-2, IL-8, interferon-alpha, and interferon-gamma. The results underscore the importance of IL-6 in the cascade of cytokines for the neuroendocrine response during the acute phase reaction. In addition, IL-6 appears to be involved in changes of sleep and behavior accompanying infection and inflammatory disorders.

Slow wave sleep drives inhibition of pituitary-adrenal secretion in humans

During the first half of nocturnal sleep, the secretory response of the pituitary-adrenal axis to either CRH or vasopressin (VP) administration is reduced. Two experiments were performed aiming (i) to investigate the impact of sleep on the response to a combined CRH/VP administration and (ii) to specify the onset of sleep associated pituitary-adrenal suppression and its relation to specific sleep stages. In experiment I, we compared the effect of simultaneous administration of VP (0.5 IU i.v., within 6 min) and CRH (50 micrograms bolus i.v., in the third min of VP infusion) on the secretion of ACTH, cortisol and GH in healthy men during the first nocturnal epoch of slow wave sleep (SWS) and during nocturnal wakefulness. The increase of ACTH and cortisol concentrations after combined VP/CRH administration was distinctly higher during wakefulness than sleep (P < 0.01). In experiment II, CRH (30 micrograms/h, after an initial bolus of 30 micrograms) was continuously infused in 7 healthy men on 2 nights. On one of the nights, the men were allowed to sleep (between 23.00 h and 05.00 h) after a 3-h period of wakefulness, on the other night they stayed awake throughout the experiment. In both conditions, CRH enhanced ACTH/cortisol plasma levels. Compared with concentrations during continuous wakefulness, sleep and in particular SWS was associated with a suppression of ACTH/cortisol levels (P < 0.05). The findings further support an inhibitory influence of early nocturnal sleep on pituitary-adrenal activity. The effect appears to be strongest during SWS and is probably mediated via hypothalamic secretion of a release inhibiting factor of ACTH.

Children's estimates of food portion size: the development and evaluation of three portion size assessment tools for use with children

A number of methods have been developed to assist subjects in providing an estimate of portion size but their application in improving portion size estimation by children has not been investigated systematically. The aim was to develop portion size assessment tools for use with children and to assess the accuracy of children's estimates of portion size using the tools. The tools were food photographs, food models and an interactive portion size assessment system (IPSAS). Children (n 201), aged 4–16 years, were supplied with known quantities of food to eat, in school. Food leftovers were weighed. Children estimated the amount of each food using each tool, 24 h after consuming the food. The age-specific portion sizes represented were based on portion sizes consumed by children in a national survey. Significant differences were found between the accuracy of estimates using the three tools. Children of all ages performed well using the IPSAS and food photographs. The accuracy and precision of estimates made using the food models were poor. For all tools, estimates of the amount of food served were more accurate than estimates of the amount consumed. Issues relating to reporting of foods left over which impact on estimates of the amounts of foods actually consumed require further study. The IPSAS has shown potential for assessment of dietary intake with children. Before practical application in assessment of dietary intake of children the tool would need to be expanded to cover a wider range of foods and to be validated in a ‘real-life’ situation.

Estimation of psychometric functions from adaptive tracking procedures

Because adaptive tracking procedures are designed to avoid stimulus levels far from a target threshold value, the psychometric function constructed from the trial-by-trial data in the track may be accurate near the target level but a poor reflection of performance at levels far removed from the target. A series of computer simulations was undertaken to assess the reliability and accuracy of psychometric functions generated from data collected in up-down adaptive tracking procedures. Estimates of psychometric function slopes were obtained from trial-by-trial data in simulated adaptive tracks and compared with the true characteristics of the functions used to generate the tracks. Simulations were carried out for three psychophysical procedures and two target performance levels, with tracks generated by psychometric functions with three different slopes. The functions reconstructed from the tracking data were, for the most part, accurate reflections of the true generating functions when at least 200 trials were included in the tracks. However, for 50- and 100-trial tracks, slope estimates were biased high for all simulated experimental conditions. Correction factors for slope estimates from these tracks are presented. There was no difference in the accuracy and reliability of slope estimation due to target level for the adaptive track, and only minor differences due to psychophysical procedure. It is recommended that, if both threshold and slope of psychometric functions are to be estimated from the trial-by-trial tracking data, at least 100 trials should be included in the tracks, and a three- or four-alternative forced-choice procedure should be used. However, good estimates can also be obtained using the two-alternative forced-choice procedure or less than 100 trials if appropriate corrections for bias are applied.

Automated malaria detection by depolarization of laser light

Anecdotal experience with full blood count (FBC) technology incorporating analysis of depolarized laser light (DLL) for the enumeration of eosinophils showed that malaria infection generated unusual distributions in the white cell channels. The objective of this study was to identify and define criteria for a diagnosis of malaria using this technology. To determine sensitivity, specificity, and positive and negative predictive values, 224 directed samples referred specifically for malaria were used; true positives were defined as those in which malaria was identified by microscopic and/or immunological methods. For the DLL method, positive was defined as one or more large mononuclear cell(s) for which the 90 degrees depolarized signal exceeded the 90 degrees polarized signal. To determine possible utility in a routine haematology laboratory setting, 220 random undirected FBC samples were evaluated for possible malaria infection by the DLL method. Of the 224 directed samples, 95 were malaria positive as determined by microscopic and/or immunological methods, and 129 were negative. For the DLL method, overall sensitivity was 72% (90% in the case of Black Africans), and specificity 96%. Positive and negative predictive values overall were 93% and 82% respectively. In the utility study a single positive result was identified among the 220 samples studied. This was found to be from a patient with malaria. The detection of unexpected malaria by automated screening FBC analysis could substantially lower the mortality and morbidity from unascertained infection, especially in indigenous African peoples.

Traumatic brain injury: patterns of failure of nonoperative management

OBJECTIVE

The circumstances of failure for nonoperative management of blunt traumatic brain injury have been poorly defined. In this study, all trauma patients identified over a 12-year period with progression of neurologic injury requiring craniotomy were retrospectively reviewed.

METHODS

Data collected included demographic information, mechanism of injury, field and admission vital signs, and Glasgow Coma Scale score, medications, associated injuries, and coagulopathy. Head computed tomographic scans were reviewed, and anatomic findings were correlated with clinical changes (change in mental status or elevation of intracranial pressure) that led to subsequent CT scan and craniotomy.

RESULTS

Of 20,100 patients, there were 852 who had computed tomographic scans with acute intracranial injuries on admission; 462 patients were managed nonoperatively. Fifty-seven patients had progression of neurologic injury (34 < 24 hours = early; 23 > 24 hours = late) that required surgery.

CONCLUSION

Of the variables investigated, only anatomic location of injury was found to be predictive of early failure of nonoperative management. Frontal intraparenchymal hematomas are particularly prone to early failure. Clinical examination and intracranial pressure monitoring are equally important in detecting failure and should be an integral part of nonoperative management.

Enhanced dynamic complexity in the human EEG during creative thinking

This study shows that divergent thinking, considered the general process underlying creative production, can be distinguished from convergent, analytical thought based on the dimensional complexity of ongoing electroencephalographic (EEG) activity. EEG complexity over the central and posterior cortex was higher while subjects solved tasks of divergent than convergent thinking, and also higher than during mental relaxation. Over the frontal cortex, EEG complexity was comparable during divergent thinking and mental relaxation, but reduced during convergent thinking. Results indicate that the basic process underlying the generation of novel ideas expresses itself in a strong increase in the EEG's complexity, reflecting higher degrees of freedom in the competitive interactions among cortical neuron assemblies. Frontocortical EEG complexity being comparable with that during mental relaxation, speaks for a loosened attentional control during creative thinking.

Sleep and endocrine changes after intranasal administration of growth hormone-releasing hormone in young and aged humans

Systemic administration of growth hormone-releasing hormone (GHRH) has been found to improve human sleep in previous studies. Here we examined effects of GHRH on endocrine function and sleep after intranasal administration, a method which based on previous studies appears to enable a direct effect of peptides on brain function. Also, it was hypothesized that elderly humans displaying deficient GH release and sleep, benefit from GHRH administration more than young subjects. A study was performed according to a double-blind cross-over design. Each of 12 young and 11 old healthy men were intranasally administered with 300 micrograms GHRH (vs. placebo) 30 min before bedtime at 23:00 h. Sleep was recorded polysomnographically until 07:00 h and blood was collected in 15 min intervals for determination of cortisol and GH. Apart from the well-known age-related changes of hormonal secretion and sleep, intranasal GHRH reduced cortisol nadir concentrations in the beginning of sleep (P < 0.05), and also reduced the sleep-induced elevation in GH concentrations during early sleep. Moreover, results indicated that after intranasal administration GHRH increased rapid-eye-movement (REM) sleep and slow wave sleep (SWS), with this influence concentrating on the second half of sleep time. Effects of GHRH did not depend on the subject's age. We conclude that there is a coordinate influence of intranasal GHRH on the central nervous regulation of sleep processes and of hypothalamic-hypophysiotropic secretory activity in both young and elderly men. The effects may mimic the dual neuronal and endocrine function of hypothalamic GHRH activity.

Immunoassay methods used in clinical studies for the detection of anti-drug antibodies to adalimumab and infliximab

We examined the assay formats used to detect anti-drug antibodies (ADA) in clinical studies of the anti-tumour necrosis factor (TNF) monoclonal antibodies adalimumab and infliximab in chronic inflammatory disease and their potential impact on pharmacokinetic and clinical outcomes. Using findings of a recent systematic literature review of the immunogenicity of 11 biological/biosimilar agents, we conducted an ancillary qualitative review of a subset of randomized controlled trials and observational studies of the monoclonal antibodies against anti-TNF factor adalimumab and infliximab. Among studies of adalimumab and infliximab, the immunoassay method used to detect antibodies was reported in 91 of 111 (82%) and 154 of 206 (75%) adalimumab and infliximab studies, respectively. In most adalimumab and infliximab studies, an enzyme-linked immunosorbent assay or radioimmunoassay was used [85 of 91 (93%) and 134 of 154 (87%), respectively]. ADA incidence varied widely among assays and inflammatory diseases (adalimumab, 0-87%; infliximab, 0-79%). Pharmacokinetic and clinical outcomes were only reported for ADA-positive patients in 38 of 91 (42%) and 61 of 154 (40%) adalimumab and infliximab studies, respectively. Regardless of assay format or biological used, ADA formation was associated with lower serum concentrations, reduced efficacy and elevated rates of infusion-related reactions. Consistent with previous recommendations to improve interpretation of immunogenicity data for biologicals, greater consistency in reporting of assay methods and clinical consequences of ADA formation may prove useful. Additional standardization in immunogenicity testing and reporting, application of modern, robust assays that satisfy current regulatory expectations and implementation of international standards for marketed products may help to improve our understanding of the impact of immunogenicity to biologics.

Effect of glycerol on intracellular virus survival: implications for the clinical use of glycerol-preserved cadaver skin

Glycerol has long been used for the preservation of skin allografts. The antimicrobial activity of glycerol has not been fully documented. This paper reports the results of an investigation of a model studying the effect of glycerol on the inactivation of intracellular viruses. Two viruses--herpes simplex type I (HSV-1) and poliovirus--were cultured within human dermal fibroblasts. These intracellular viruses were incubated with 50 per cent, 85 per cent and 98 per cent glycerol at 4 degrees C and 20 degrees C for 4 weeks. Each week, the cultures in glycerol and controls in fibroblast maintenance medium were assayed for virus infectivity by examining the ability of harvested viruses to infect further fibroblasts. At 4 degrees C, 85 per cent glycerol could not fully inactivate intracellular HSV-I or poliovirus even after 4 weeks; 98 per cent glycerol inactivated intracellular HSV-I (after 3 weeks) but could not fully inactivate intracellular poliovirus after 4 weeks. At 20 degrees C, 85 per cent glycerol inactivated intracellular HSV-I (within 1 week) but could not fully inactivate intracellular poliovirus after 4 weeks; 98 per cent glycerol inactivated intracellular HSV-I (within 1 week) and inactivated intracellular poliovirus (after 2 weeks). It is suggested that, on the basis of this study, glycerol can reduce intracellular virus infectivity but that its effects are very dependent on concentration, time and temperature such that we would recommend that allograft skin be exposed to 98 per cent glycerol for a minimum of at least 4 weeks at a minimum temperature of 20 degrees C before clinical use.

The concentration of 13,14-dihydro-15-keto prostaglandin F2 alpha and prostaglandin E2 in peritoneal fluid of infertile patients with and without endometriosis

Prostaglandin F2 alpha (PGF2 alpha) metabolite (13,14-dihydro-15-keto PGF2 alpha) and prostaglandin E2 (PGE2) were assayed in the cul-de-sac fluid aspirated from 15 patients with endometriosis, in saline peritoneal washings of 5 patients with unexplained infertility, and in 5 control subjects. The fluid from the cul-de-sac of patients with endometriosis showed wide variations in the concentrations of PGF2 alpha metabolite and PGE2. There was no correlation between the concentration of these prostaglandins (PGs) and the stage of the cycle. Saline peritoneal washings from patients with unexplained infertility had significantly higher concentrations of PGF2 alpha metabolite than the control subjects. The concentration of PGE2 in the saline peritoneal washings was higher in the group with unexplained infertility than in the control group; however, the difference was not significant. The concentration of PGF2 alpha metabolite and PGE2 in the peritoneal saline washings from patients with unexplained infertility were no different from the concentrations of these PGs in the peritoneal fluid (PF) from patients with endometriosis. PG concentration in PF of infertile patients with or without endometriosis is a new variable for evaluation in these patients.

Auditory processing in aging listeners

Many aspects of auditory processing in aging listeners are poorly understood. Methodological problems encountered with the aging population, ranging from ear canal collapse to a conservative criterion, have rarely been considered in past research. The relation between pure-tone thresholds and other aspects of auditory functions is unclear. There have been few studies of frequency and temporal analysis in aging listeners. There is disagreement on the effect of age on speech discrimination abilities in various listening conditions, and the cause of speech perception problems in aging listeners has not been adequately investigated. Areas of importance for clinical consideration and auditory research with aging listeners are discussed.

Occurrence and spatial distribution of chemical contaminants in edible fish species collected from UK and proximate marine waters

The occurrence of a range of regulated and emerging organic environmental contaminants was investigated in 182 samples of edible marine fish sampled mainly from UK marine regions, but extending northerly to the coast of Norway and south to the Algarve. These species (sprats, mackerel, turbot, halibut, herring, grey mullet, sea bass, grey mullet, sardines, etc.) are among those considered to be at the highest risk of contamination with regulated contaminants such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs, dioxins), and polychlorinated biphenyls (PCBs), but the occurrence of polybrominated diphenylethers (PBDEs) and polybrominated biphenyls (PBBs) was also investigated. Sub-sets of samples (50-75) were also analysed for emerging contaminants: polychlorinated naphthalenes (PCNs), polybrominated and mixed halogenated dibenzo-p-dioxins, dibenzofurans and biphenyls (PBDD/Fs, PXDD/Fs and PXBs) and perfluoroalkyl substances (PFAS). Contaminant occurrence varied with species and location, but all measured contaminants were detected, with sprats, sea bass, sardines, mackerel, and herring showing higher tissue concentrations. The concentrations of the different contaminants in the various samples were mapped utilising the GPS coordinate data of the capture locations to visualise spatial distribution levels. In terms of catch location, fish sampled from the coasts of southern Britain, north-western France and the Irish Sea appeared to contain proportionately higher levels of some contaminants - e.g. samples from the Irish Sea tended to show higher PCN concentrations, whereas higher levels of PCBs were observed in some fish sampled off the coasts of northern France. Similarly, samples of mullet from the southeast coast of UK showed much higher concentrations of BDE-99 than the other regions. In terms of occurrence trends, PCDD/F and PCB concentrations show a modest decline over the last decade but where limited background data is available for emerging contaminants, there is no evidence of downward trends.