Characterization of Influenza B Virus Variants with Reduced Neuraminidase Inhibitor Susceptibility.

Treatment options for influenza B virus infections are limited to neuraminidase inhibitors (NAIs), which block the neuraminidase (NA) glycoprotein on the virion surface. The development of NAI resistance would therefore result in a loss of antiviral treatment options for influenza B virus infections. This study characterized two contemporary influenza B viruses with known resistance-conferring NA amino acid substitutions, D197N and H273Y, detected during routine surveillance. The D197N and H273Y variants were characterized in vitro by assessing NA enzyme activity and affinity, as well as replication in cell culture compared to those of NAI-sensitive wild-type viruses. In vivo studies were also performed in ferrets to assess the replication and transmissibility of each variant. Mathematical models were used to analyze within-host and between-host fitness of variants relative to wild-type viruses. The data revealed that the H273Y variant had NA enzyme function similar to that of its wild type but had slightly reduced replication and transmission efficiency in vivo The D197N variant had impaired NA enzyme function, but there was no evidence of reduction in replication or transmission efficiency in ferrets. Our data suggest that the influenza B virus variant with the H273Y NA substitution had a more notable reduction in fitness compared to wild-type viruses than the influenza B variant with the D197N NA substitution. Although a D197N variant is yet to become widespread, it is the most commonly detected NAI-resistant influenza B virus in surveillance studies. Our results highlight the need to carefully monitor circulating viruses for the spread of influenza B viruses with the D197N NA substitution.

Doctors' health: obstacles and enablers to returning to work.

BACKGROUND: For doctors returning to work after absence due to ill-health or performance concerns, the obstacles can seem insurmountable. Doctors' perspectives of these obstacles have been investigated. To support them more effectively, the perspectives of organizations that interact with such doctors should also be considered. AIMS: To explore the obstacles and enablers to doctors' return to work after long-term absence from the perspective of key organizations involved in assessment and support. METHODS: We identified organizations operating in the field of doctors' health, well-being and performance. We conducted semi-structured, 30-45 min telephone interviews with representatives of the organizations, exploring problems that they had encountered that were experienced by doctors with health or performance concerns returning to work after absence of a month or longer. We analysed our field notes using theoretical analysis. RESULTS: We conducted 11 telephone interviews. Data analysis identified four key themes of obstacles and enablers to returning to work: 'communication', 'return to work', 'finance and funding' and 'relationships and engagement'. Sub-themes relating to the organization and the individual also emerged. CONCLUSIONS: Organizations responsible for supporting doctors back to work reported poor communication as a significant obstacle to doctors returning to work after illness. They also reported differences between specialities, employing organizations, occupational health departments and human resources in terms of knowledge and expertise in supporting doctors with complex issues. Clear communication channels, care pathways and support processes, such as workplace advocates, were perceived as strong enablers to return to work for doctors after long-term absence.

Update on narcolepsy.

The last two decades have seen an explosion in our understanding of the clinical nature of narcolepsy and its pathogenesis, fuelling new approaches to potentially effective treatments. It is now recognised that the full narcoleptic syndrome has significant adverse effects on sleep regulation across the full 24-h period and is often associated with clinical features outside the sleep-wake domain. The discovery that most narcoleptic subjects specifically lack a hypothalamic neuropeptide (hypocretin, also called orexin) was a truly original and landmark observation in 1999, greatly furthering our understanding both of the syndrome itself and sleep biology in general. An autoimmune pathophysiology has long been suggested by the tight association with specific histocompatibility antigens and very recently partly confirmed by detailed analysis of T-cell immunological function in affected subjects. Drug treatments remain symptomatic but may soon become more focussed by restoring central hypocretin signalling with replacement therapy. Potentially disease-modifying, immunological approaches have yet to be studied systematically, although the interval between disease onset and development of the full clinical syndrome may be longer than previously appreciated, affording a realistic window of opportunity for limiting neuronal damage in this disabling condition.

Characterization of substitutions in the neuraminidase of A(H7N9) influenza viruses selected following serial passage in the presence of different neuraminidase inhibitors.

Avian A(H7N9) infections in humans have been reported in China since 2013 and are of public health concern due to their severity and pandemic potential. Oseltamivir and peramivir are neuraminidase inhibitors (NAIs) routinely used for the treatment of A(H7N9) infections, but variants with reduced sensitivity to these drugs can emerge in patients during treatment. Zanamivir and laninamivir are NAIs that are used less frequently. Herein, we performed in vitro serial passaging experiments with recombinant viruses, containing the neuraminidase (NA) from influenza A/Anhui/1/13 (H7N9) virus, in the presence of each NAI, to determine whether variants with reduced sensitivity would emerge. NA substitutions were characterized for their effect on the NA enzymatic activity and surface expression of the A/Anhui/1/13 (Anhui/1) NA, as well as NAs originating from contemporary A(H7N9) viruses of the Yangtze River Delta and Pearl River Delta lineages. In vitro passage in the presence of oseltamivir, peramivir and laninamivir selected for substitutions associated with reduced sensitivity (E119D, R292K and R152K), whereas passage in the presence of zanamivir did not select for any viruses with reduced sensitivity. All the NA substitutions significantly reduced activity, but not the expression of the Anhui/1 NA. In contemporary N9 NAs, all substitutions tested significantly reduced NA enzyme function in the Yangtze River lineage background, but not in the Pearl River Delta lineage background. Overall, these findings suggest that zanamivir may be less likely than the other NAIs to select for resistance in A(H7N9) viruses and that the impact of substitutions that reduce NAI susceptibility or enzyme function may be less in A(H7N9) viruses from the Pearl River lineage.

EFNS guidelines on management of narcolepsy.

Management of narcolepsy with or without cataplexy relies on several classes of drugs, namely stimulants for excessive daytime sleepiness and irresistible episodes of sleep, antidepressants for cataplexy and hypnosedative drugs for disturbed nocturnal sleep. In addition, behavioral measures can be of notable value. Guidelines on the management of narcolepsy have already been published. However contemporary guidelines are necessary given the growing use of modafinil to treat excessive daytime sleepiness in Europe within the last 5-10 years, and the decreasing need for amphetamines and amphetamine-like stimulants; the extensive use of new antidepressants in the treatment of cataplexy, apart from consistent randomized placebo-controlled clinical trials; and the present re-emergence of gamma-hydroxybutyrate under the name sodium oxybate, as a treatment of all major symptoms of narcolepsy. A task force composed of the leading specialists of narcolepsy in Europe has been appointed. This task force conducted an extensive review of pharmacological and behavioral trials available in the literature. All trials were analyzed according to their class evidence. Recommendations concerning the treatment of each single symptom of narcolepsy as well as general recommendations were made. Modafinil is the first-line pharmacological treatment of excessive daytime sleepiness and irresistible episodes of sleep in association with behavioral measures. However, based on several large randomized controlled trials showing the activity of sodium oxybate, not only on cataplexy but also on excessive daytime sleepiness and irresistible episodes of sleep, there is a growing practice in the USA to use it for the later indications. Given the availability of modafinil and methylphenidate, and the forseen registration of sodium oxybate for narcolepsy (including excessive daytime sleepiness, cataplexy, disturbed nocturnal sleep) in Europe, the place of other compounds will become fairly limited. Since its recent registration cataplexy sodium oxybate has now become the first-line treatment of cataplexy. Second-line treatments are antidepressants, either tricyclics or newer antidepressants, the later being increasingly used these past years despite few or no randomized placebo-controlled clinical trials. As for disturbed nocturnal sleep the best option is still hypnotics until sodium oxybate is registered for narcolepsy. The treatments used for narcolepsy, either pharmacological or behavioral, are diverse. However the quality of the published clinical evidences supporting them varies widely and studies comparing the efficacy of different substances are lacking. Several treatments are used on an empirical basis, specially antidepressants for cataplexy, due to the fact that these medications are already used widely in depressed patients, leaving little motivation from the manufacturers to investigate efficacy in relatively rare indications. Others, in particular the more recently developed substances, such as modafinil or sodium oxybate, are evaluated in large randomized placebo-controlled trials. Our objective was to reinforce the use of those drugs evaluated in randomized placebo-controlled trials and to reach a consensus, as much as possible, on the use of other available medications.

CSF antigliadin antibodies and the Ramsay Hunt syndrome.

Although the association between celiac disease and progressive myoclonic ataxia is well recognized, in each of the reported cases the neurologic features began in middle adult life and usually in patients who had clinical or laboratory evidence of malabsorption. We report a case of progressive myoclonic ataxia and epilepsy (Ramsay Hunt syndrome) that began in childhood. In this patient there were no features suggestive of gluten intolerance. The presence of antigliadin antibodies in the serum and CSF suggested celiac disease was the cause of the patient's neurologic syndrome. Duodenal morphologic abnormalities reversed with treatment but no major changes were noted in the patient. Celiac disease should be considered in the differential diagnosis of myoclonic ataxia at any age, even in the absence of clinical evidence of gluten-sensitive enteropathy.

The effects of d-amphetamine, alpha-flupenthixol, and mesolimbic dopamine depletion on a test of attentional switching in the rat.

A test of attentional switching was devised for the rat in which it obtained sucrose reinforcement by an appropriate nose-poke response that discriminated which of two visual events terminated first, in a specially designed chamber. The effect of mesolimbic dopamine depletion (to 20% of control values) produced by infusions of 6-hydroxydopamine (6-OHDA) into the nucleus accumbens (N. Acc) on stable discrimination was measured alone and in the presence of a range of doses of d-amphetamine (0.4-2.3 mg/kg IP). The 6-OHDA lesion of the N. Acc impaired postoperative performance transiently by reducing choice accuracy and slowing response latency. By post-operative days 12-16, however, performance recovered to control levels and was not differentially affected by a manipulation of task difficulty. d-Amphetamine produced dose-dependent performance impairments, which were antagonised by the 6-OHDA treatment. In a second group of N. Acc lesioned rats, the neuroleptic alpha-flupenthixol (0.1-1.0 mg/kg) led to fewer trials being completed and longer latencies than in the sham-operated control group. The results are discussed in terms of the possible attentional mechanisms underlying the d-amphetamine-induced disruption of performance mediated by the N. Acc and of the implications for psychopathology resulting from possible dysfunction of this region.

The effects of excitotoxic lesions of the nucleus accumbens on a matching to position task.

The effects of bilateral ibotenic acid lesions of the nucleus accumbens in the rat were examined on a delayed matching to position task. The lesion induced a stable delay-dependent performance deficit suggestive of a short-term memory problem. Following analysis of the impaired performance on trials with long delays, using measures akin to signal detection indices, the deficit was interpreted as being largely due to the intrusion of a side-dependent response bias. Low-dose amphetamine (0.75 mg/kg) produced a similar disruption in the sham-operated rats, both in terms of accuracy impairment and degree of strategical bias. As well as mimicking the effects of low-dose amphetamine in sham-operated rats, the lesion also protected against the disruptive effects of the drug at low doses. Whilst exhibiting no performance deficit when the matching schedule lacked a delay component, the lesioned rats were very significantly impaired in switching their response strategies when exposed to a series of reversals. In addition, the lesioned rats were remarkably resistant to an extinction procedure. Both these findings indicate that the lesioned rats were unable to exhibit flexibility in their response patterns. These results, taken together with those of the delayed matching procedure, imply that one of the functions of the intact nucleus accumbens is to inhibit habitual responding under conditions of non-reward and low stimulus control, possibly via its connections to the dorsal striatal system.

Dissociable roles of the ventral, medial and lateral striatum on the acquisition and performance of a complex visual stimulus-response habit.

The effects of discrete bilateral ibotenic acid lesions to 3 areas of striatum were examined on a conditional visual discrimination task involving temporal frequency (SLOW vs FAST flashes) that had previously been shown to be sensitive to the effects of dorsal striatal dopamine depletion. Two of the groups, namely, those with nucleus accumbens (ACC) and lateral caudate-putamen (LCP) lesions, were very disrupted in the acquisition of the task. The nature of the respective impairments of the 2 groups was dissociable, however. The performance of the ACC group could be improved either by manipulations of stimulus duration or inter-stimulus interval, implying an attentional deficit. In contrast, the rats with lesions of the LCP were not significantly improved by any of the behavioural challenges. Their performance was characterised by a bias to respond to the SLOW discriminandum. Under conditions of non-reward, the LCP group extinguished their responding at a similar rate to control rats whereas the ACC group were very much more persistent. Lesions of the medial caudate-putamen failed to affect any index of performance significantly. These data suggest that the LCP is necessary for the acquisition of arbitrary stimulus-response rules and that damage to an equivalent area in humans, such as in Huntington's disease, may explain deficits of procedural memory. The second part of the experiment investigated the effects of ACC lesions on established performance of the schedule. The lesioned group behaved identically to the ACC group that had been lesioned prior to acquisition, both in terms of accuracy and degree of persistence in extinction, further implying the role of attentional factors and inflexibility in the lesion-induced deficit.

Effects of dopamine depletion from the caudate-putamen and nucleus accumbens septi on the acquisition and performance of a conditional discrimination task.

Three experiments compared the effects of dopamine depletion from the caudate-putamen (CAUD; dorsal striatum) or nucleus accumbens septi (NAS; ventral striatum), or a systemically administered dopamine receptor antagonist (alpha-flupenthixol) on the acquisition and performance of a conditional discrimination task involving temporal frequency. In Expt. 1, rats receiving 6-hydroxydopamine (6-OHDA) lesions of the CAUD were impaired in the acquisition of a visual version of the task, and rats with 6-OHDA lesions of the NAS were not reliably impaired. Even when the rats with CAUD lesions had acquired the discrimination, they were still significantly slower to collect earned food pellets. Both CAUD and NAS lesions reduced a bias to respond to the faster of the two discriminative stimuli. In Expt. 2, rats with 6-OHDA lesions of CAUD were markedly impaired in their accuracy and speed of responding when they had been trained to criterion preoperatively. These effects could not be mimicked in controls by prefeeding (which had only minor effects on performance). Rats with 6-OHDA-induced lesions of the NAS were unimpaired in either visual or auditory discrimination performance, but were slower to extinguish responding than controls. In Expt. 3, alpha-flupenthixol (0.1-0.56 mg/kg, i.p.) produced dose-dependent impairments in both latency to respond and choice accuracy in visual and auditory versions of the task. In conjunction with other results, these data suggest that (1) dopamine receptor blockade and central dopamine depletion can impair discrimination performance under certain conditions (2) dopamine depletion from the ventral and dorsal striatum, respectively, have dissociable effects on behaviour controlled by conditioned reinforcers and discriminative stimuli and (3) the disruption of discrimination performance by dorsal striatal dopamine depletion is probably attributable to several factors.

Application of probability of paternity calculations to an alleged incestuous relationship.

An alleged case of incest between half siblings has been examined by standard blood grouping and human leukocyte antigen (HLA) serology. The data were analyzed statistically using single and joint possibilities of paternity. The existence of the alleged relationship between the two parties in question is quite probable.

The effect of differences in gene frequency on probability of paternity.

Knowledge of gene frequencies in populations is required for the calculation of probability of paternity. The question remains open as to the degree of accuracy of gene frequency estimates required to give accurate probability of paternity figures. This is of special concern in the HLA system, which has haplotype frequencies known to vary in populations. This paper presents computer simulation data comparing probability of paternity calculations using HLA data from California and North Carolina. Comparisons were made between geographic regions, and between blacks and whites within a geographic region. It was found that when the absolute probability of paternity is high, the average differences induced were small, but at lower probabilities the changes can be large. Differences were most pronounced between black and white populations. Examples of individual cases are given to illustrate the huge differences that can be induced in some cases by changing gene frequency.

Frontal lobe dysfunction in schizophrenia and Parkinson's disease--a meeting point for neurology, psychology and psychiatry: discussion paper.

The psychotic features of schizophrenia and the motor problems of Parkinson's disease, respectively, allow striking contrasts to be made between the two disorders. However, it has recently become apparent that the two groups of patients share problems of mentation that are best explained by some dysfunction of the prefrontal cortical areas of the brain. These commonalities are addressed in terms of neurobiological fact and psychological theory, providing possible insight into the neuropsychology of schizophrenia and its dichotomous nature. In particular, the putative role of abnormal frontostriatal interactions in the two disease states is emphasized.

Peritonitis in continuous ambulatory peritoneal dialysis.

The main complication of continuous ambulatory peritoneal dialysis (CAPD) is peritonitis. This paper describes our experience in the diagnosis and management of this complication in 66 patients during the three years to October 1982. The overall incidence of peritonitis was one episode every 6.75 patient months. Staphylococcus albus and Staphylococcus aureus together accounted for 46 per cent of the episodes, and 24 per cent were culture negative. Catheter exit site infections due to Staphylococcus aureus were common and they may have predisposed to peritonitis with gram -ve organisms as well as to staphylococcal peritonitis. Antimicrobial therapy was effective in 60 per cent of peritonitis episodes. The culture negative episodes usually responded to treatment while those due to fungi, though uncommon, did not. Twenty-nine per cent of these CAPD patients were transferred to haemodialysis because of peritonitis which failed to respond to treatment or which recurred repeatedly.

Aerosolized therapy for ventilator-assisted patients.

Although aerosols, especially bronchodilators, are routinely administered to ventilator-assisted patients, the practice lacks scientific proof that it improves the outcome of respiratory failure. Using sensitive instruments, investigators have found that aerosolized bronchodilators lead to improvement in airflow immediately following the treatment; however, no study to date has correlated short-term improvement in pulmonary function to a decreased incidence of barotrauma or reduced need for mechanical ventilation. Multiple variables interfere with optimum delivery of aerosols to ventilator-assisted patients, including the endotracheal tube, patient and ventilator breathing pattern, and the inefficiency of nebulizer systems. Recent evidence suggests that if aerosols are used to treat intubated patients, metered-dose inhalers are the devices of choice in terms of cost and efficacy.

Things that go bump in the night: diagnosing sleep-related movement disorders without a sleep laboratory.

It is common for general physicians to experience diagnostic doubt and trepidation whenever faced with patients who exhibit abnormal nocturnal behaviours or excessive movements at night. There is also a perception that expensive and often poorly available overnight tests are usually required for diagnostic precision. In fact, the majority of conditions, whether they be parasomnias or, more rarely, nocturnal seizures, can be reliably diagnosed from a directed history, if available. Although the evidence base for treating parasomnias and sleep-related movement disorders remains minimal, accurate recognition is important for a variety of reasons. This review covers the diagnostic features of the full range of parasomnias and movement disorders that might present to a multidisciplinary adult sleep clinic. Throughout, it will be argued that the recognition of key or salient features obtained from a good history is the most important diagnostic tool. Indeed, when diagnostic doubt remains after a thorough sleep history, it is relatively rare for detailed tests to add much in the way of useful information.

Embryonic striatal grafts reverse the disinhibitory effects of ibotenic acid lesions of the ventral striatum.

Bilateral damage to the ventral striatum induced by the excitotoxin ibotenic acid was found to have profound disinhibitory effects on rats' behaviour. Lesioned animals were unable to acquire efficient levels of performance on an operant schedule (differential reinforcement of low rates of responding, DRL) that required them to inhibit a previously rewarded response. In addition, lesioned subjects were relatively resistant to the disruptive effects of amphetamine on performance of the DRL schedule and were slower to cease responding under conditions of non-reward. A measure of unconditioned behaviour, overnight locomotor activity, was also disinhibited by the presence of the lesion. Grafts of embryonic striatal tissue transplanted to the lesioned ventral striatum were found to survive well. Moreover, the presence of the grafts reversed the effects of the lesion on measures of conditioned and unconditioned behaviour. The nature of the lesion-induced behavioural deficit and the ability of the embryonic transplants to reverse it are discussed in terms of the possible restoration of limbi-subcortical circuitry.

Involvement of the mannose receptor in infection of macrophages by influenza virus.

Influenza viruses A/PR/8/34 (PR8; H1N1), A/Aichi/68 X-31 (HKx31; H3N2), and A/Beijing/89 X-109 (BJx109; H3N2) show marked differences in their ability to infect murine macrophages, including resident alveolar and peritoneal macrophages as well as the macrophage-derived cell line J774. The hierarchy in infectivity of the viruses (PR8 < HKx31 < BJx109) resembles that of their reactivity with mannose-binding lectins of the collectin family. Since the macrophage mannose receptor recognizes the same spectrum of monosaccharides as the collectins do, we investigated the possible involvement of this receptor in infection of macrophages by influenza virus. In competitive binding studies, the binding of (125)I-labeled mannosylated bovine serum albumin to macrophages was inhibited by the purified hemagglutinin and neuraminidase (HANA) glycoproteins of influenza virus but not by HANA that had been treated with periodate to oxidize its oligosaccharide side chains. The inhibitory activity of HANA from the three strains of virus differed markedly and correlated with the infectivity of each virus for macrophages. Infection of macrophages, but not MDCK cells, by influenza virus was inhibited by yeast mannan. A variant line of J774 cells, J774E, which expresses elevated levels of the mannose receptor, was more readily infected than J774, and the sensitivity of J774E cells to infection was greatly reduced by culture in the presence of D-mannose, which down-modulated mannose receptor expression. Together, the data implicate the mannose receptor as a major endocytic receptor in the infectious entry of influenza virus, and perhaps other enveloped viruses, into murine macrophages.