Endogenous melatonin levels and therapeutic use of exogenous melatonin in tension type headache: A systematic review.

BACKGROUND-PURPOSE: A bidirectional relationship appears to connect tension-type headache (TTH) and circadian dysregulation. The present systematic review examined the published evidence for melatonin (MT) supplementation in the prophylaxis of TTH. Initially, we reviewed case-control studies investigating nocturnal MT or 6-sulphatoxymelatonin (aMT6s, a urine-discarded metabolite) in TTH individuals and healthy controls (HC). Secondly, we reviewed studies appraising the use of MT in the prevention of TTH. METHODS: The search strategy involved MEDLINE EMBASE, CENTRAL, PsycINFO, trial registries, Google Scholar and OpenGrey. Case-control studies were appraised according to the Newcastle-Ottawa-Scale, whereas randomised controlled trials were assessed based on the risk-of-bias Cochrane tool. Infrequent, as well as frequent, episodic, and chronic TTH patients were evaluated separately in children and adults. RESULTS: Our search strategy yielded two case-control studies. One (high-quality) did not reveal any difference in morning salivary MT concentration between children with frequent episodic TTH and HC. The second (moderate-quality) was indicative of a disturbed nocturnal secretion pattern in adults with chronic TTH. For the second part, five uncontrolled studies were retrieved. In total, 94 adults with chronic TTH were assessed and results were suggestive of a beneficial effect of MT on headache frequency, intensity, induced disability, and induced analgesic consumption. However, the uncontrolled-unblinded designs may have induced an important placebo effect. Non-adult populations and frequent TTH were substantially understudied. CONCLUSIONS: There are not enough studies to designate the role of MT in the prevention of TTH. Given the disease's background, additional relevant research is warranted for chronic TTH.

Viruses and endogenous retroviruses in multiple sclerosis: From correlation to causation.

Multiple sclerosis is an immune-mediated disease with an environmental component. According to a long-standing but unproven hypothesis dating to initial descriptions of multiple sclerosis (MS) at the end of the 19th century, viruses are either directly or indirectly implicated in MS pathogenesis. Whether viruses in MS are principally causal or simply contributory remains to be proven, but many viruses or viral elements-predominantly Epstein-Barr virus, human endogenous retroviruses (HERVs) and human herpesvirus 6 (HHV-6) but also less common viruses such as Saffold and measles viruses-are associated with MS. Here, we present an up-to-date and comprehensive review of the main candidate viruses implicated in MS pathogenesis and summarize how these viruses might cause or lead to the hallmark demyelinating and inflammatory lesions of MS. We review data from epidemiological, animal and in vitro studies and in doing so offer a transdisciplinary approach to the topic. We argue that it is crucially important not to interpret "absence of evidence" as "evidence of absence" and that future studies need to focus on distinguishing correlative from causative associations. Progress in the MS-virus field is expected to arise from an increasing body of knowledge on the interplay between viruses and HERVs in MS. Such interactions suggest common HERV-mediated pathways downstream of viral infection that cause both neuroinflammation and neurodegeneration. We also comment on the limitations of existing studies and provide future research directions for the field.

Age-specific application of neutrophil-to-lymphocyte ratio in meningitis: a nationwide study.

Cerebrospinal fluid (CSF) neutrophil counts and neutrophil-to-lymphocyte ratio (NLR) are useful in distinguishing bacterial and viral meningitis. Given that meningitis is clinically heterogeneous with regard to age, here we investigated the validity of the CSF NLR and neutrophil assay according to age group. Data from the nationwide referral of >4,000 meningitis cases to the Hellenic Meningitis Reference Laboratory between 2006 and 2013 were examined. CSF NLR and neutrophil counts were stratified according to age, and assay performance was determined using previous cut-off values of 2 and 287 cells/µl for CSF NLR and neutrophils respectively. The distribution of bacterial versus viral meningitis was heterogenous across age groups, with a low proportion of bacterial meningitis in patients aged 5-14. CSF neutrophil count and NLR were significantly more discriminatory for bacterial meningitis in patients aged over 14 years than those aged 0-14. The odds ratio (OR), sensitivity, specificity and positive predictive value (PPV) were significantly higher in older patients for both biomarkers. When combined, the false-positive and false-negative detection of bacterial meningitis was 3.9 and 8.5% respectively, and the OR of 262.2 was 2.5-fold greater than expected from a multiplicative effect alone in patients aged >14 years. Care is required when applying diagnostic tests for meningitis in different age groups because of patient heterogeneity. This is the first description of the age distribution of meningitis cases in Greece, and knowledge of the age-related distribution of neutrophils and NLR in meningitis cases could help towards developing age-specific meningitis diagnostic assays.

Antiviral susceptibility profile of influenza A viruses; keep an eye on immunocompromised patients under prolonged treatment.

There was an increase in severe and fatal influenza cases in Greece during the 2011-2015 post-pandemic period. To investigate causality, we determined neuraminidase (NA) inhibitor susceptibility and resistance-conferring NA and hemagglutinin (HA) mutations in circulating influenza type A viruses during the pandemic (2009-2010) and post-pandemic periods in Greece. One hundred thirty-four influenza A(H1N1)pdm09 and 95 influenza A(H3N2) viruses submitted to the National Influenza Reference Laboratory of Southern Greece were tested for susceptibility to oseltamivir and zanamivir. Antiviral resistance was assessed by neuraminidase sequence analysis, as well as the fluorescence-based 50 % inhibitory concentration (IC50) method. Five influenza A(H1N1)pdm09 viruses (2.2 %) showed significantly reduced inhibition by oseltamivir (average IC50 300.60nM vs. 1.19nM) by Gaussian kernel density plot analysis. These viruses were isolated from immunocompromised patients and harbored the H275Y oseltamivir resistance-conferring NA substitution. All A(H1N1)pdm09 viruses were zanamivir-susceptible, and all A(H3N2) viruses were susceptible to both drugs. Oseltamivir-resistant viruses did not form a distinct cluster by phylogenetic analysis. Permissive mutations were detected in immunogenic and non immunogenic NA regions of both oseltamivir- resistant and susceptible viruses in the post-pandemic seasons. Several amino acid substitutions in the HA1 domain of the HA gene of post-pandemic viruses were identified. This study indicated low resistance to NAIs among tested influenza viruses. Antiviral resistance emerged only in immunocompromised patients under long-term oseltamivir treatment. Sequential sample testing in this vulnerable group of patients is recommended to characterise resistance or reinfection and viral evolution.

Epigenomic engineering for Down syndrome.

Down syndrome (DS; trisomy 21), the commonest genetic cause of mental disability, affects approximately 250,000 families in the United States alone. Despite milestones in understanding the specific genetic causes of the syndrome, the major symptoms of DS - not least those related to neurocognitive function - are incurable. DS phenotypes are highly variable, and gene expression patterns cannot be explained by trisomy alone, implicating epigenetics in DS pathophysiology. DNA and histone modifications appear to contribute to DS pathology and cognitive defects, and epigenomic, and genome editing research have very recently opened up novel therapeutic avenues for several diseases including DS. Here, we discuss how epigenomic therapies might be used to ameliorate DS-related phenotypes with a particular focus on the CRISPR-Cas 9 system for targeted epigenomic engineering in DS. This approach is likely to reap rewards in terms of understanding the pathophysiology of DS, especially when combined with animal models, but significant technical and ethical challenges must be overcome for clinical translation.

Neutrophil-to-lymphocyte ratio in the differential diagnosis of acute bacterial meningitis.

The differential diagnosis of acute community-acquired meningitis is of paramount importance in both therapeutic and healthcare-related economic terms. Despite the routinely used markers, novel, easily calculated, and rapidly available biomarkers are needed particularly in resource-poor settings. A promising, exponentially studied inflammatory marker is the neutrophil-to-lymphocyte ratio (NLR), albeit not assessed in meningitis. The aim of this study was to investigate the utility of the NLR in the differential diagnosis of acute meningitis. Data on cerebrospinal fluid (CSF) and blood leukocyte parameters from more than 4,000 patients diagnosed with either bacterial or viral meningitis in Greece during the period 2006-2013 were retrospectively examined. The diagnostic accuracy of the NLR and neutrophil counts in CSF and blood were evaluated by receiver operating characteristic curves. The discrimination ability of both the NLR and neutrophil counts was significantly higher in CSF than in blood. The optimal cutoff values of the NLR and neutrophil counts were 2 in CSF vs 8 in blood, and 287 cells in CSF vs 12,100 cells in blood, respectively. For these values, sensitivity, negative predictive value, and odds ratio were statistically significantly higher in CSF than blood for both markers. Logistic regression analysis showed that the CSF NLR carries independent and additive information to neutrophil counts in the differential diagnosis of acute meningitis. This study is the first one to assess NLR in acute meningitis, providing promising results for its differential diagnosis.

Low oxygen tension enhances hepatitis C virus replication.

Low oxygen tension exerts a significant effect on the replication of several DNA and RNA viruses in cultured cells. In vitro propagation of hepatitis C virus (HCV) has thus far been studied under atmospheric oxygen levels despite the fact that the liver tissue microenvironment is hypoxic. In this study, we investigated the efficiency of HCV production in actively dividing or differentiating human hepatoma cells cultured under low or atmospheric oxygen tensions. By using both HCV replicons and infection-based assays, low oxygen was found to enhance HCV RNA replication whereas virus entry and RNA translation were not affected. Hypoxia signaling pathway-focused DNA microarray and real-time quantitative reverse transcription-PCR (qRT-PCR) analyses revealed an upregulation of genes related to hypoxic stress, glycolytic metabolism, cell growth, and proliferation when cells were kept under low (3% [vol/vol]) oxygen tension, likely reflecting cell adaptation to anaerobic conditions. Interestingly, hypoxia-mediated enhancement of HCV replication correlated directly with the increase in anaerobic glycolysis and creatine kinase B (CKB) activity that leads to elevated ATP production. Surprisingly, activation of hypoxia-inducible factor alpha (HIF-α) was not involved in the elevation of HCV replication. Instead, a number of oncogenes known to be associated with glycolysis were upregulated and evidence that these oncogenes contribute to hypoxia-mediated enhancement of HCV replication was obtained. Finally, in liver biopsy specimens of HCV-infected patients, the levels of hypoxia and anaerobic metabolism markers correlated with HCV RNA levels. These results provide new insights into the impact of oxygen tension on the intricate HCV-host cell interaction.

Rare association of sensorimotor polyneuropathy and Klinefelter syndrome (47,XXY): case report.

OBJECTIVES: To describe a case with the rare association of Klinefelter syndrome (47,XXY) and peripheral sensorimotor polyneuropathy. CLINICAL PRESENTATION AND INTERVENTION: A 50-year-old man with Klinefelter syndrome was referred to our neurology clinic complaining of pain, numbness and tingles in both legs, which began 10 years prior to admission. Two years before admission, the patient had difficulty in walking with progressive weakness. CONCLUSION: This report shows a patient with diagnosed Klinefelter syndrome, in whom symmetrical sensorimotor polyneuropathy developed in late adulthood.

Helicobacter pylori infection in spouses of patients with duodenal ulcers and comparison of ribosomal RNA gene patterns.

BACKGROUND: In recent studies, familial coinfection with the same Helicobacter pylori strains has been indicated, but more data are necessary to confirm intra-familial spread of the micro-organism. AIMS: The aim of this study was (a) to assess the frequency of H pylori infection in spouses of patients with duodenal ulcers and (b) to investigate the possibility of intraspousal typing of the respective strains. PATIENTS: Sixty four patients with duodenal ulcer and their spouses were included in the study. METHODS: The H pylori infection was confirmed after endoscopy by culture and histological examination of biopsy specimens, and CLO test. The isolates were compared on the basis of their rRNA gene patterns (ribopatterns) after digestion of chromosomal DNA by the restriction endonucleases HaeIII or HindIII. RESULTS: Of the patients, 54 were found to be H pylori positive. Of the respective spouses, 42 (78%) were also H pylori positive. In contrast, only two out of 10 (20%) partners of H pylori negative patients were infected. Ribopatterns of H pylori strains derived from 18 patients and their spouses showed that in each of eight couples a single strain had colonised both partners, while in the remaining 10 couples each partner was colonised by a distinct H pylori strain. CONCLUSIONS: These data suggest person to person transmission within couples or exposure to a common source of infection.

Characterization of a novel SHV beta-lactamase variant that resembles the SHV-5 enzyme.

An SHV type beta-lactamase frequently found in enterobacteria isolated in Greek hospitals was analyzed. The enzyme (SHV-5a) conferred resistance to ceftazidime and aztreonam. The DNA sequence of the structural gene was determined. The deduced amino acid sequence showed that positions 70-73 were occupied by the active site tetrad Ser-Thr-Phe-Lys. As in SHV-5, Ser-238 and Lys-240 were present. However, one deletion (Gly-54) and three substitutions (Arg-140 for Ala, Asn-192 for Lys and Val-193 for Leu) differentiate SHV-5a beta-lactamase from SHV-5. Asn-192 and Val-193 have been reported to date only in the R974 plasmid-mediate SHV-1 beta-lactamase. Hydrolysis studies with SHV-5a and SHV-5 showed that the enzymes behaved similarly. Additional evidence that they are functionally indistinguishable was provided by the similar MICs of beta-lactams when the enzymes were expressed under isogenic conditions. The sequence differences, however, indicate that they are derived from different ancestors.

In vitro activity of cefpirome against selected clinical enterobacterial isolates with beta-lactamase-mediated resistance.

Previous studies have shown that there is a high incidence of resistance to cephalosporins among enterobacteria isolated in Greek hospitals. This resistance is mainly due to either the derepression of chromosomal cephalosporinases or the acquisition of plasmids coding for SHV-5 type beta-lactamase. In the present study the activity of cefpirome against a number of enterobacteria (Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes and Serratia marcescens) possessing the mechanisms mentioned above was examined. Cefpirome was found active against all the strains characterized by stable derepression of chromosomal class-C enzymes. The antibiotic was less potent against strains expressing SHV-5 type beta-lactamase due to its hydrolysis by the enzyme. Also cefpirome exhibited good activity against E. aerogenes strains with reduced susceptibility to imipenem. These in vitro data suggest that cefpirome might be useful in treating infections caused by these resistant microorganisms that are frequently encountered in Greek hospitals.

Nucleotide sequence of a plasmid-mediated cephalosporinase gene (blaLAT-1) found in Klebsiella pneumoniae.

The nucleotide sequence of the gene encoding a novel cephalosporinase (LAT-1), carried by a non-self-transferable plasmid from Klebsiella pneumoniae, has been determined. It was found that the sequence shares a high degree of homology with the Citrobacter freundii OS60 ampC structural gene.

Dissemination of cephalosporin-resistant Serratia marcescens strains producing a plasmidic SHV type beta-lactamase in Greek hospitals.

The resistance to third generation cephalosporins in nine Serratia marcescens strains isolated in Greek hospitals was studied. Eight of the strains transferred resistance to Escherichia coli by means of large plasmids that encoded for an extended-spectrum beta-lactamase. Hybridization, isoelectric focusing and hydrolysis studies showed that the enzyme resembled the SHV-5 beta-lactamase. In the eight isolates that possessed the SHV type enzyme, cephalosporinase expression was inducible, whereas the remaining strain was a cephalosporinase hyperproducing strain. Introduction of a plasmid coding for the regulatory ampD gene in the latter strain eliminated beta-lactamase production and rendered the strain susceptible to cephalosporins.

Consecutive mutations leading to the emergence in vivo of imipenem resistance in a clinical strain of Enterobacter aerogenes.

Three consecutive isolates of Enterobacter aerogenes were obtained from the blood cultures of a hospitalised patient who was receiving antibiotic therapy. The initial isolate possessed an inducible cephalosporinase and was susceptible to third-generation cephalosporins. After ceftazidime treatment, a second isolate resistant to this antibiotic and characterised by stable overproduction of the chromosomal beta-lactamase was obtained, and therapy was altered to a new combination which included imipenem. During this course of treatment, a strain of E. aerogenes was isolated that was resistant to virtually all beta-lactam agents including imipenem. Comparison of biotypes and ribotyping profiles indicated that the three isolates were probably derived from a single strain which had undergone several mutations during antibiotic exposure. Examination of outer-membrane protein (OMP) preparations and lipopolysaccharide (LPS) profiles showed that the imipenem-resistant isolate lacked a major OMP and high molecular mass LPS. Furthermore, this isolate displayed reduced permeability to cephaloridine compared with the initial isolate. The introduction of a plasmid carrying a wild-type ampD allele prevented cephalosporinase production and restored beta-lactam susceptibility in the imipenem-resistant isolate. It was concluded that stable derepression of class-I beta-lactamase production and reduced permeability are both required for expression of imipenem resistance in E. aerogenes, and that previous exposure to cephalosporins may encourage the emergence of such strains.

Identification of a novel plasmid-mediated beta-lactamase with chromosomal cephalosporinase characteristics from Klebsiella pneumoniae.

A clinical isolate of Klebsiella pneumoniae resistant to a wide variety of beta-lactams, including third generation cephalosporins, aztreonam and cephamycins, as well as to beta-lactam/clavulanate and sulbactam combinations was examined. It was found that this resistance was transmissible to Escherichia coli recipients via a small 5.3 MDa plasmid encoding for an unusual beta-lactamase produced in relatively large quantities. The enzyme, designated LAT-1, exhibited a highly basic isoelectric point (pI = 9.4) and its hydrolytic activity resembled closely that of a class-I chromosomal cephalosporinase. In vitro, LAT-1 hydrolysed cephaloridine, cephalothin and cephalexin more rapidly than penicillins. A slow hydrolysis of cefoxitin, ceftibuten, ceftazidime and cefotaxime was also observed. The enzyme was inhibited by low concentrations of aztreonam and cloxacillin but it was virtually unaffected by clavulanate. Under stringent conditions, the LAT-1 encoding plasmid did not hybridize with probes specific for TEM-1 and Enterobacter cloacae AmpC beta-lactamase genes. The plasmid was not self-transferable but was readily mobilized by a conjugative R-plasmid harboured by the same K. pneumoniae strain.

Imipenem resistance in Enterobacter aerogenes is associated with derepression of chromosomal cephalosporinases and impaired permeability.

Enterobacter aerogenes mutants with high-level resistance to imipenem were studied. They were derived from strains characterized by stable over-production of a class-I beta-lactamase. This enzyme (pI = 8.2) exhibited high affinity toward imipenem and hydrolysed the drug slowly. Imipenem-resistant mutants lacked a major 43-kDa outer membrane protein and displayed decreased permeability to cephaloridine. Introduction of a plasmid coding for the regulatory ampD gene abolished beta-lactamase production and rendered the mutants susceptible to imipenem.

High prevalence of stably derepressed class-I beta-lactamase expression in multiresistant clinical isolates of Enterobacter cloacae from Greek hospitals.

Susceptibilities to cefotaxime (Ctx) and ceftazidime (Caz) were examined for 90 recent clinical isolates of Enterobacter cloacae from Greek hospitals. Most (68%) of the isolates were resistant to both drugs, and all were resistant to cefoxitin. beta-Lactamase activities against cephaloridine in crude extracts from Ctx-Caz-resistant isolates were high, irrespective of whether or not the cells were grown with cefoxitin as an inducer of the chromosomal beta-lactamase, indicating stable derepression of the gene for the enzyme. On the other hand, double disk antagonism tests showed that all the Ctx-Caz-sensitive isolates possessed inducible expression of this beta-lactamase. Iso-electric focusing revealed the presence of five forms of the chromosomal beta-lactamase, randomly distributed amongst the Ctx-Caz-resistant and -sensitive isolates. Plasmid-mediated beta-lactamases of TEM and PSE types also were found in many isolates. These data indicate that the extremely high prevalence of Ctx-Caz-resistant E. cloacae isolates in Greek hospitals is attributed to the dissemination of mutants which constitutively overproduce the class-I chromosomal beta-lactamase. Over 90% of these isolates exhibited cross-resistance to aminoglycosides, suggesting the accumulation of unrelated antibiotic resistance mechanisms.

Exposure effects of netilmicin on Enterobacter cloacae clinical isolates.

The effects of netilmicin exposure on two aminoglycoside (AMG)-resistant and two AMG-susceptible Enterobacter cloacae isolates were studied. It was found that 1 h incubation of bacterial suspensions with netilmicin at 16 mg/l reduces the amounts of lipopolysaccharides present on the bacterial surface. Also, netilmicin pretreatment increased both the susceptibility to normal human serum and the adhesion to human epithelial cells of all four E. cloacae strains examined.

In vitro binding of Helicobacter pylori to human gastric mucin.

The in vitro binding of four Helicobacter pylori strains to human gastric mucin was studied with an enzyme-linked immunosorbent assay. All four strains were found to bind to purified mucin. Neuraminidase treatment and nonspecific oxidation of mucin decreased bacterial adherence to the macromolecule. Mucin preparations were also found to inhibit attachment of H. pylori to HEp-2 monolayers.