Natural human antibody responses to Plasmodium vivax apical membrane antigen 1 under low transmission and unstable malaria conditions in Sri Lanka

Plasmodium vivax apical membrane antigen 1, an important malaria vaccine candidate, was immunogenic during natural malaria infections in Sri Lanka, where low transmission and unstable malaria conditions prevail. Antibody prevalence increased with exposure in areas where malaria was or was not endemic. A marked isotype switch to cytophilic (immunoglobulin G1 [IgG1]/IgG3) antibodies was evident with increasing exposure exclusively in residents from areas of endemicity.     

<Emphasis Type="Italic">Terminalia bellirica</Emphasis> fruit extracts: in-vitro antibacterial activity against selected multidrug-resistant bacteria,radical scavenging activity and cytotoxicity study on BHK-21 cells

Background

Identification of novel sources for developing new antibiotics is imperative with the emergence of antibiotic resistant bacteria. The fruits of Terminalia bellirica (Gaertn) Roxb., widely used in traditional medicine, were evaluated for antibacterial activity against multidrug-resistant (MDR) bacteria, antioxidant activity and cytotoxicity.

Methods

Twelve solvent extracts of T. bellirica fruits were prepared by direct aqueous extraction and sequential extraction with dichloromethane, methanol and water using Soxhlet, bottle-shaker and ultrasound sonicator methods. Antibacterial activity of the extracts was tested against 16 strains MDR bacteria—methicillin-resistant Staphylococcus aureus (MRSA), extended spectrum β-lactamase (ESBL) producing Escherichia coli and MDR Acinetobacter spp., Klebsiella pneumoniae and Pseudomonas aeruginosa—and 4 control organisms, using the cut-well diffusion method. The minimum inhibitory concentration (MIC) was determined using an agar dilution method. The radical scavenging activity of six antibacterial extracts was screened against 2,2′-diphenyl-2-picrylhydrazyl (DPPH) and correlation was established between EC₅₀ (50% effective concentration) values and the total phenolic content (TPC). Cytotoxicity was determined for the most potent antibacterial extract on baby hamster kidney (BHK-21) cells by Tryphan Blue exclusion method. Statistical analysis was carried out by one-way analysis of variance at significant level p?<?0.05 using “SigmaPlot 10” and “R 3.2.0” software.

Results

All aqueous and methanol extracts displayed antibacterial activity (MIC 0.25–4?mg/mL) against all strains of MRSA, MDR Acinetobacter spp. and MDR P. aeruginosa. The sequential aqueous extracts (MIC, 4?mg/mL) inhibited ESBL producing-E. coli. None of the extracts exhibited activity against MDR K. pneumoniae (MIC >?5?mg/mL). The sequential methanol extract (Soxhlet) recorded high antibacterial activity and the highest DPPH radical scavenging activity (EC₅₀, 6.99?±?0.15?ppm) and TPC content (188.71?±?2.12 GAE mg/g).The IC₅₀ (50% inhibition concentration) values of the most potent antibacterial extract—the direct aqueous extract from reflux method—on BHK-21 cells were 2.62?±?0.06 and 1.45?±?0.08?mg/ml with 24 and 48?h exposure, respectively.

Conclusions

Results indicate that T. bellirica fruit is a potential source for developing broad-spectrum antibacterial drugs against MDR bacteria, which are non-toxic to mammalian cells and impart health benefits by high antioxidant activity.

     

Enteric gram‐negative bacilli suppress Candida biofilms on Foley urinary catheters

Mixed Candida‐bacterial biofilms in urinary catheters are common in hospitalized patients. (i) The aims of this study were to evaluate, quantitatively and qualitatively, the in vitro development of mono‐ and dual‐species biofilms (MSBs and DSBs) of Candida albicans and two enteric gram‐negative bacilli (EGNB; Pseudomonas aeruginosa or Escherichia coli) on Foley catheter (FC) discs, (ii) to determine the biofilm growth in tryptic soy broth or glucose supplemented artificial urine (AU) and (iii) to assess the inhibitory effects of EGNB and their lipopolysaccharides (LPS) on Candida biofilm growth. The growth of MSBs and DSBs on FC discs was monitored by cell counts and SEM. The metabolic activity of LPS‐treated Candida biofilms was determined by the XTT reduction assay. Candida albicans and EGNB demonstrated significant inter‐ and intra‐species differences in biofilm growth on FC discs (p < 0.01). Pseudomonas aeruginosa suppressed Candida albicans significantly (p < 0.001) in DSBs. Compared with MSBs, DSB of EGNB in glucose supplemented AU demonstrated robust growth. Escherichia coli and its LPS, significantly suppressed Candida biofilm growth, compared with Pseudomonas aeruginosa and its LPS (p < 0.001). Candida albicans and EGNB colonization in FC is significantly increased in AU with glucose, and variably modified by Escherichia coli, Pseudomonas aeruginosa and their corresponding LPS.     

Microbial chemical signaling: a current perspective

Communication among microorganisms is mediated through quorum sensing. The latter is defined as cell-density linked, coordinated gene expression in microbial populations as a response to threshold signal concentrations followed by induction of a synchronized population response. This phenomenon is used by a variety of microbes to optimize their survival in a constantly challenging, dynamic milieu, by correlating individual cellular functions to community-based requirements. The synthesis, secretion, and perception of quorum-sensing molecules and their target response play a pivotal role in quorum sensing and are tightly controlled by complex, multilayered and interconnected signal transduction pathways that regulate diverse cellular functions. Quorum sensing exemplifies interactive social behavior innate to the microbial world that controls features such as, virulence, biofilm maturation, antibiotic resistance, swarming motility, and conjugal plasmid transfer. Over the past two decades, studies have been performed to rationalize bacterial cell-to-cell communication mediated by structurally and functionally diverse small molecules. This review describes the theoretical aspects of cellular and quorum-sensing mechanisms that affect microbial physiology and pathobiology.     

An enigma of spontaneous combined transdiaphragmatic, intercostal and abdominal wall hernia

Introduction

Cough can be associated with many complications.

Materials and methods

We present a 59-year-old male patient with a very rare combination of a cough-related stress fracture of the ninth rib and herniation through the diaphragm and abdominal wall to the subcutaneous tissue of the chest wall. We suggest thoracotomy through the affected intercostal defect as a surgical approach. The diaphragm, chest wall and abdominal tears were repaired separately, and the abdominal wall was reinforced with mesh. Technical aspects were discussed.

Conclusions

Though each individual injury is well documented in the literature, this is a rare combination of defects, requiring early recognition to provide repair before incarceration and further enlargement of the defects occur.     

Natural radioactivity and gamma dose from Sri Lankan clay bricks used in building construction.

The specific radioactivity concentrations of 226Ra, 232Th and 40K have been determined by gamma ray spectrometry with an HPGe detector in clay brick samples from kiln sites located in 17 towns. The average values of the measured activities are 35, 72, and 585 Bq kg(-1), respectively, for the above radionuclides. The average estimated radium equivalent concentration is 183 Bq kg(-1) and is comparable with reported values for many countries in the world. This value and the value obtained from the criteria formula suggest that the use of local clay bricks do not pose a radiological hazard. The calculated average absorbed dose rate in air within buildings was found to be 102 nGy h(-1) while the population weighted indoor annual effective dose was 0.20 mSv.