Clostridium and Bacillus Binary Enterotoxins: Bad for the Bowels,and Eukaryotic Being

Some pathogenic spore-forming bacilli employ a binary protein mechanism for intoxicating the intestinal tracts of insects, animals, and humans. These Gram-positive bacteria and their toxins include Clostridium botulinum (C2 toxin), Clostridium difficile (C. difficile toxin or CDT), Clostridium perfringens (ι-toxin and binary enterotoxin, or BEC), Clostridium spiroforme (C. spiroforme toxin or CST), as well as Bacillus cereus (vegetative insecticidal protein or VIP). These gut-acting proteins form an AB complex composed of ADP-ribosyl transferase (A) and cell-binding (B) components that intoxicate cells via receptor-mediated endocytosis and endosomal trafficking. Once inside the cytosol, the A components inhibit normal cell functions by mono-ADP-ribosylation of globular actin, which induces cytoskeletal disarray and death. Important aspects of each bacterium and binary enterotoxin will be highlighted in this review, with particular focus upon the disease process involving the biochemistry and modes of action for each toxin.     

Iron Oxide Nanoparticles Induces Cell Cycle-Dependent Neuronal Apoptosis in Mice

Iron oxide (Fe₂O₃) nanoparticles (NPs) with its unique magnetic and paramagnetic properties are popular in biomedical applications. Some of their neurotoxic mechanisms due to repeated administration are proven. However, we speculate that the neuronal damage might be due to apoptosis resulting from unusual cell cycle entry. Moreover, iron accumulation has been shown to be closely associated with most of the neurodegenerative disorders. Thus, in the current study, mice were orally (po) treated with the Fe₂O₃-NPs to investigate cell cycle-associated events/components and occurrence of apoptosis. A subsequent increase in oxidant levels was observed with the iron accumulation due to Fe₂O₃-NPs exposure. The accumulated β-amyloid and reduced level of cdk5 seem to aid in the cell cycle entry and forcing progression towards apoptosis. Expression of Cyclin D1 and pRb (Ser 795) indicate the cell cycle re-entry of neurons. Overexpression of RNA Pol II and PARP cleavage suggests DNA damage due to Fe₂O₃-NPs exposure. Further, hyperphosphorylation of p38 (Thr 180/Tyr 182) confirms the activation of DNA damage-dependent checkpoint. Expression patterns of pro- and anti-apoptotic markers, TUNEL and TEM indicate the occurrences of apoptosis.     

Comparison of Reverse Sural Artery Flap Healing for Traumatic Injuries Above and Below the Ankle Joint

The reverse sural artery (RSA) flap is popular among trauma surgeons to cover the distal third of the leg to the foot. However, flaps that inset in the foot seem to have a high necrosis rate. This study compared the healing of RSA flaps performed for defects proximal to the ankle versus defects distal to the ankle. Patient data were collected retrospectively between January 2005 and December 2009. Eighty-five patients with the lower leg, ankle, and traumatic foot injuries were divided into 2 groups. Group 1 (49 patients) had RSA flap cover for soft tissue and bony defect proximal and up to the ankle joint line, and group 2 (36 patients) had RSA flap cover distal to the ankle joint line. The time to healing and type of healing were compared between the groups. The demographics between the 2 groups were similar. The successful RSA flap healing rate was 65% in group 1 (32 of 49) and 42% in group 2 (15 of 36). The average time to flap healing between the groups was similar (p?=?.16). Group 1 had predominantly primary healing compared with group 2 (p?=?.03). Group 2 had a higher reoperation rate for wound necrosis, which was significant (p?=?.001). The success of the RSA flap is higher when used for proximal to ankle joint line defects. Surgeons should be aware of the chances of flap necrosis when undertaking RSA flap cover distal to the ankle joint line.     

Transactional sex and the challenges to safer sexual behaviors: a study among male sex workers in Chennai,India

Male sex workers (MSW) are a significant but invisible population in India who are at risk for HIV/sexually transmitted infections (STIs). Few studies from India have documented HIV risk factors and motivations for sex work in this population. Between 2013 and 2014, a community-based convenience sample of 100 MSW in Chennai (south India) completed a baseline risk assessment as part of a behavioral intervention. Participants were ≥18 years, and reported current sex work. We report medians and proportions, and Wilcoxon–Mann–Whitney and chi-square tests are used to examine differences between sex work and sexual behavior measures by income source. Participants were engaged in sex work for 5.0 years (IQR?=?2.3–10.0), and earned 3000 (IQR?=?2000–8000) Rupees (<50 USD) per month from sex work. Sixty-four percent reported ever testing for HIV and 20.2% for any STI. The most common reasons for starting sex work were money (83.0%) and pleasure (56.0%). Compared to participants with an additional source of income, those whose only source of income was sex work reported more male clients in the past month (10.0 vs. 6.0, p?=?.017), as well as more condomless anal sex acts with male clients (8.0 vs. 5.0, p?=?.008). Nearly 70.0% were offered more money not to use a condom during sex with a client, and 74.2% reported accepting more money not to use a condom. Three-quarters reported having experienced difficulty using condoms with clients. MSW in India engage in high levels of sexual risk for HIV/STIs. Money appears to be a driving factor for engaging in sex work and condomless sex with clients. HIV prevention interventions with MSW should focus on facilitating skills that will support their ability to negotiate sexual safety in the context of monetary disincentives.     

Magnetic Field-Assisted Photocatalytic Degradation of Organic Pollutants over Bi1−xRxFeO3 (R = Ce,Tb; x = 0.00, 0.05, 0.10 and 0.15) Nanostructures

Magnetic-field-accelerated photocatalytic degradation of the phenol red (PR) as a model organic pollutant was studied using rare-earth elements modified BiFeO₃ (Bi_1−xR_xFeO₃ (R = Ce, Tb; x = 0.0, 0.05, 0.10 and 0.15); BFO: RE) nanostructures. The nanostructures were prepared via the hydrothermal process and their morphological, structural, functional, optical and magnetic features were investigated in detail. The effect of magnetic fields (MFs) on photocatalysis were examined by applying the different MFs under visible light irradiation. The enhanced photodegradation efficiencies were achieved by increasing the MF up to 0.5T and reduced at 0.7T for the compositions x = 0.10 in both Ce and Tb substituted BFO. Further, mineralization efficiencies of PR, reproducibility of MF-assisted photocatalysis, stability and recyclability of BFO: RE nanostructures were also tested.     

Use of amino acids as counterions improves the solubility of the BCS II model drug, indomethacin

The number of new chemical entities (NCE) is increasing every day after the introduction of combinatorial chemistry and high throughput screening to the drug discovery cycle. One third of these new compounds have aqueous solubility less than 20μg/mL [1]. Therefore, a great deal of interest has been forwarded to the salt formation technique to overcome solubility limitations. This study aims to improve the drug solubility of a Biopharmaceutical Classification System class II (BCS II) model drug (Indomethacin; IND) using basic amino acids (L-arginine, L-lysine and L-histidine) as counterions. Three new salts were prepared using freeze drying method and characterised by FT-IR spectroscopy, proton nuclear magnetic resonance ((1)HNMR), Differential Scanning Calorimetry (DSC) and Thermogravimetric analysis (TGA). The effect of pH on IND solubility was also investigated using pH-solubility profile. Both arginine and lysine formed novel salts with IND, while histidine failed to dissociate the free acid and in turn no salt was formed. Arginine and lysine increased IND solubility by 10,000 and 2296 fold, respectively. An increase in dissolution rate was also observed for the novel salts. Since these new salts have improved IND solubility to that similar to BCS class I drugs, IND salts could be considered for possible waivers of bioequivalence.     

Antigen detection assay with parasite specific monoclonal antibodies for diagnosis of lymphatic filariasis

BackgroundLymphatic filariasis is a painful and profoundly disfiguring disease. Infection is usually acquired in childhood but its visible manifestations occur later in life, causing temporary or permanent disability. The importance of developing effective assays to diagnose, monitor and evaluate human lymphatic filariasis has been emphasized by the WHO.MethodsHigh-affinity monoclonal antibodies (mAbs) specific for recombinant filarial antigen WbSXP-1 were developed. An ELISA based capture assay using monoclonal and polyclonal antibodies for WbSXP-1 was used for detection of circulating filarial antigen.ResultsHigh-affinity monoclonal antibodies (mAbs) were developed that specifically binds both W. bancrofti and B. malayi mf antigens. Two mAbs (1F6H3 and 2E12E3) of subclass IgG2a and IgM showed high affinity, avidity and reactivity to recombinant and mf native antigen. Both the mAbs were used in combination as capture antibodies and polyclonal as detection antibody to develop the assay. The assay showed very high sensitivity towards W. bancrofti mf positive samples compared to endemic normal samples (P < 0.0001).ConclusionA capture assay using high-affinity monoclonal antibodies for WbSXP-1 was developed for the detection of filarial circulating antigen in clinical samples from bancroftian infection. Besides, this would also help in epidemiological studies in endemic areas of filarial infections.     

Novel antitubercular diallyl/dibenzylthiosemicarbazones endowed with high activity toward multi-drug-resistant tuberculosis

Novel diallyl and dibenzylthiosemicarbazones were prepared by three-step reactions. The compounds were tested for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB) and multi-drug-resistant Mycobacterium tuberculosis (MDR-TB). Most of the compounds showed excellent activity toward MDR-TB. Among the thirty compounds (4,5a–o) tested N,N-dibenzyl-2-((5-nitrofuran-2-yl)methylene)hydrazinecarbothioamide (5g) was found to be the most potent compound MICs of 0.55 and 0.12 μM against MTB and MDR-TB.     

Identification of a novel skin penetration enhancement peptide by phage display peptide library screening

Skin is an important site for local or systemic application of drugs. However, a majority of drugs have poor permeability through the skin's topmost layer, stratum corneum (SC). The aim of this study was to identify safe and smaller peptides that could enhance the skin penetration of drug molecules. By screening phage display peptide library, we have identified a T2 peptide (LVGVFH), which enhanced the penetration of bacteriophages (~800 nm long bacterial viruses) across porcine and mouse skin. Pretreating the skin with synthetic T2 peptide at pH 4.5 resulted in significant penetration enhancement of hydrophilic drug 5-fluorouracil (5-FU) across skin. FTIR spectroscopy showed that the T2 peptide interacted with skin lipids to enhance the skin penetration. Pretreating the skin with T2 peptide enhanced the partitioning of small molecules with different lipophilicities (5-FU, fluorescein isothiocyanate, and rhodamine 123 hydrochloride) into skin. Fluorescence studies showed that T2 peptide enhanced the diffusion of these molecules into intercellular lipids of SC and thus enhanced the penetration into the skin. Histidine at the c-terminus of T2 peptide was identified to be critical for the skin penetration enhancement. T2 peptide interacted with skin lipids to cause skin penetration enhancement. The study identified a novel, safe, and noninvasive peptide to improve the skin penetration of drugs without chemical conjugation.