Weighted burden analysis of exome-sequenced late-onset Alzheimer's cases and controls provides further evidence for a role for PSEN1 and suggests involvement of the PI3K/Akt/GSK-3β and WNT signalling pathways

Previous studies have implicated common and rare genetic variants as risk factors for late-onset Alzheimer's disease (LOAD). Here, weighted burden analysis was applied to over 10,000 exome-sequenced subjects from the Alzheimer's Disease Sequencing Project. Analyses were carried out to investigate whether rare variants predicted to have a functional effect within a gene were more commonly seen in cases or in controls. Confirmatory results were obtained for TREM2, ABCA7, and SORL1. Additional support was provided for PSEN1 (p = 0.0002), which previously had been only weakly implicated in LOAD. There was suggestive evidence that functional variants in PIK3R1, WNT7A, C1R, and EXOC5 might increase risk and that variants in TIAF1 and/or NDRG2 might have a protective effect. Overall, there was strong evidence (p = 5 × 10⁻⁶) that variants in tyrosine phosphatase genes reduce the risk of developing LOAD. Because PIK3R1 variants are expected to impair PI3K/Akt/GSK-3β signalling while variants in tyrosine phosphatase genes would enhance it, these findings are in line with those from animal models, suggesting that this pathway is protective against Alzheimer's disease.     

Macrophage-mediated optic neuritis induced by retrograde axonal transport of spike gene recombinant mouse hepatitis virus

After intracranial inoculation, neurovirulent mouse hepatitis virus (MHV) strains induce acute inflammation, demyelination, and axonal loss in the central nervous system. Prior studies using recombinant MHV strains that differ only in the spike gene, which encodes a glycoprotein involved in virus-host cell attachment, demonstrated that spike mediates anterograde axonal transport of virus to the spinal cord. A demyelinating MHV strain induces optic neuritis, but whether this is due to the retrograde axonal transport of viral particles to the retina or due to traumatic disruption of retinal ganglion cell axons during intracranial inoculation is not known. Using recombinant isogenic MHV strains, we examined the ability of recombinant MHV to induce optic neuritis by retrograde spread from the brain through the optic nerve into the eye after intracranial inoculation. Recombinant demyelinating MHV induced macrophage infiltration of optic nerves, demyelination, and axonal loss, whereas optic neuritis and axonal injury were minimal in mice infected with the nondemyelinating MHV strain that differs in the spike gene. Thus, optic neuritis was dependent on a spike glycoprotein-mediated mechanism of viral antigen transport along retinal ganglion cell axons. These data indicate that MHV spreads by retrograde axonal transport to the eye and that targeting spike protein interactions with axonal transport machinery is a potential therapeutic strategy for central nervous system viral infections and associated diseases.     

Potential management of resistant microbial infections with a novel non-antibiotic: the anti-inflammatory drug diclofenac sodium

Diclofenac sodium (Dc), an anti-inflammatory agent, has remarkable inhibitory action both against drug-sensitive and drug-resistant clinical isolates of various Gram-positive and Gram-negative bacteria. The aim of this study was to determine the ability of Dc to protect mice from a virulent Salmonella infection. Dc injected at 1.5 microg/g and 3.0 microg/g mouse body weight significantly protected animals from the lethality of Salmonella infection. As was the case for the in vitro interaction, Dc in combination with streptomycin was even more effective. The non-antibiotic drug Dc has potential for the management of problematic antibiotic-resistant bacterial infections.     

Diclofenac in the management of E. coli urinary tract infections

E. coli is the main agent of uncomplicated urinary tract infections (UTIs) and accounts for more than 85% of recurrent cystitis and at least 35% of recurrent pyelonephritis. Despite the widespread availability of antibiotics, UTIs remain the most common bacterial infection in the human population. It is currently advised that the clinical administration of antibiotics against the pathogenic bacteria should be prohibitted due to the emergence of multidrug resistant (MDR) bacterial strains. Therefore, newer and more effective antimicrobials are in demand to treat such cases. One hundred and thirty six urine samples were collected from UTI patients. E. coli was isolated from 85 samples, out of which 33% were resistant to common antibiotics. The isolates were decreasingly resistant to ampicillin, tobramycin, augmentin, nalidixic acid, cefuroxime, nitrofurantoin, kanamycin, pipemidic acid, chloramphenicol, cefotaxime, cefamendol, ofloxacin, ceftizoxime, norfloxacin and amikacin. The anti-inflammatory drug diclofenac exhibited significant antibacterial activity against common bacterial strains both in vitro and in vivo. The present work was conducted to evaluate the in vitro inhibitory effect of this drug on the clinically isolated strains of E. coli in hospitals. All the isolates were sensitive to diclofenac, with MIC values ranging from 5-50 microg/mL. The MIC90 value of the drug was 25 microg/mL. Therefore, it may be suggested that diclofenac has the capacity to treat UTI caused by E. coli.     

Studies on the antibacterial potentiality of isoflavones

The isoflavonoid compounds 'YS11-YS21' were screened for possible antimicrobial property against 12 known Gram-positive and Gram-negative sensitive bacteria. YS11 and YS16 failed to show antimicrobial activity and YS12, 13, 14, 15, 17, 18 and 20 had moderate antimicrobial action. Compounds YS19 and YS21 showed pronounced antimicrobial property. YS19 and YS21 were then tested in vitro against 214 strains of bacteria from one Gram-positive and six Gram-negative genera. The minimum inhibitory concentration (MIC) of YS19 and YS21 was determined by agar dilution method and ranged from 25 to 200 mg/l in most strains. At concentrations of 30 and 60 microg/mouse these compounds offered significant protection to mice challenged with 50 median lethal dose (MLD) of a virulent strain of Salmonella Typhimurium.     

Evaluation of synergism between the aminoglycoside antibiotic streptomycin and the cardiovascular agent amlodipine

Amlodipine, a cardiovascular drug, exhibited remarkable antibacterial action in vitro against 504 bacterial strains belonging to both Gram positive and Gram negative genera, as well as in vivo against a mouse-virulent bacterium. Based on such findings, the present study was undertaken to determine whether the efficacy of this non-antibiotic drug could be enhanced in the presence of any antibiotic. Twelve bacterial strains, sensitive to amlodipine as well as to 6 antibiotics, viz., benzyl penicillin, streptomycin, chloramphenicol, tetracycline, erythromycin and ciprofloxacin were chosen. Disc diffusion test with amlodipine and streptomycin revealed marked synergism between the combination, compared with their individual effects. The synergism was found to be statistically significant (p<0.01). To assess the degree of synergy, the checkerboard analysis was performed. The fractional inhibitory concentration (FIC) index of this combination turned out to be 0.24, which confirmed synergism. This antibiotic-non-antibiotic pair was then administered to mice, challenged with S. typhimurium to determine whether this was effective in vivo. Statistical analysis of the mouse protection tests suggested that the combination was highly synergistic (p<0.001), according to Student's t-test. This synergistic drug combination may help us in enhancing the scope of prolonged antibiotic therapy in various types of infections, and might open a new therapeutic approach to combat drug resistance in bacterial diseases.     

Sulphaphenazole, streptomycin and sulphaphenazole combination, trimethoprim, and erythromycin in the treatment of chancroid.

One hundred and thirty six patients with chancroid were treated with four different treatment regimens; (A) Sulphaphenazole 1 g 12 hourly by mouth x 10 days (B) Inj streptomycin 1 g intramuscularly daily with sulphaphenazole 1 g 12 hourly orally x 10 days; (C) trimethoprim 200 mg 12 hourly by mouth x 7-10 days, and (D) erythromycin 500 mg 6 hourly orally x 7-10 days. Cure rates of 9% with sulphaphenazole alone, 48% with streptomycin and sulphaphenazole combination, 93% with trimethoprim and 100% with erythromycin were obtained. Sulphaphenazole alone or in combination with streptomycin were thus inferior in the treatment of chancroid. There is need for modification of treatment regimens recommended for chancroid in the textbooks of dermatology and venereology. Trimethoprim can be recommended as first line of treatment for chancroid in developing countries like India where resistance to trimethoprim is uncommon and erythromycin is suggested as a second line of therapy because by that time syphilis can be easily ruled out.     

Search for potential target site of nucleocapsid gene for the design of an epitope-based SARS DNA vaccine

It is believed today that nucleocapsid protein (N) of severe acute respiratory syndrome (SARS)-CoV is one of the most promising antigen candidates for vaccine design. In this study, three fragments [N1 (residues: 1-422); N2 (residues: 1-109); N3 (residues: 110-422)] of N protein of SARS-CoV were expressed in Escherichia coli and analyzed by pooled sera of convalescence phase of SARS patients. Three gene fragments [N1 (1-1269 nt), N2 (1-327 nt) and N3 (328-1269 nt)-expressing the same proteins of N1, N2 and N3, respectively] of SARS-N were cloned into pVAX-1 and used to immunize BALB/c mice by electroporation. Humoral (by enzyme-linked immunosorbent assay, ELISA) and cellular (by cell proliferation and CD4(+):CD8(+) assay) immunity was detected by using recombinant N1 and N3 specific antigen. Results showed that N1 and N3 fragments of N protein expressed by E. coli were able to react with sera of SARS patients but N2 could not. Specific humoral and cellular immunity in mice could be induced significantly by inoculating SARS-CoV N1 and N3 DNA vaccine. In addition, the immune response levels in N3 were significantly higher for antibody responses (IgG and IgG1 but not IgG2a) and cell proliferation but not in CD4(+):CD8(+) assay compared to N1 vaccine. The identification of antigenic N protein fragments has implications to provide basic information for the design of DNA vaccine against SARS-CoV. The present results not only suggest that DNA immunization with pVax-N3 could be used as potential DNA vaccination approaches to induce antibody in BALB/c mice, but also illustrates that gene immunization with these SARS DNA vaccines can generate different immune responses.