Serological Evidence of Chikungunya Virus among Acute Febrile Patients in Southern Mozambique

Background

In the last two decades, chikungunya virus (CHIKV) has rapidly expanded to several geographical areas, causing frequent outbreaks in sub-Saharan Africa, South East Asia, South America, and Europe. Therefore, the disease remains heavily neglected in Mozambique, and no recent study has been conducted.

Methods

Between January and September 2013, acute febrile patients with no other evident cause of fever and attending a health center in a suburban area of Maputo city, Mozambique, were consecutively invited to participate. Paired acute and convalescent serum samples were requested from each participant. Convalescent samples were initially screened for anti-CHIKV IgG using a commercial indirect immunofluorescence test, and if positive, the corresponding acute sample was screened using the same test.

Results

Four hundred patients were enrolled. The median age of study participants was 26 years (IQR: 21–33 years) and 57.5% (224/391) were female. Paired blood samples were obtained from 209 patients, of which 26.4% (55/208) were presented anti-CHIKV IgG antibodies in the convalescent sample. Seroconversion or a four-fold titer rise was confirmed in 9 (4.3%) patients.

Conclusion

The results of this study strongly suggest that CHIKV is circulating in southern Mozambique. We recommend that CHIKV should be considered in the differential diagnosis of acute febrile illness in Mozambique and that systematic surveillance for CHIKV should be implemented.     

Dual-porosity model of solute diffusion in biological tissue modified by electroporation

In many electroporation applications mass transport in biological tissue is of primary concern. This paper presents a theoretical advancement in the field and gives some examples of model use in electroporation applications. The study focuses on post-treatment solute diffusion.     

Focused ion beam (FIB)/scanning electron microscopy (SEM) in tissue structural research

The focused ion beam (FIB) and scanning electron microscope (SEM) are commonly used in material sciences for imaging and analysis of materials. Over the last decade, the combined FIB/SEM system has proven to be also applicable in the life sciences. We have examined the potential of the focused ion beam/scanning electron microscope system for the investigation of biological tissues of the model organism Porcellio scaber (Crustacea: Isopoda). Tissue from digestive glands was prepared as for conventional SEM or as for transmission electron microscopy (TEM). The samples were transferred into FIB/SEM for FIB milling and an imaging operation. FIB-milled regions were secondary electron imaged, back-scattered electron imaged, or energy dispersive X-ray (EDX) analyzed. Our results demonstrated that FIB/SEM enables simultaneous investigation of sample gross morphology, cell surface characteristics, and subsurface structures. The same FIB-exposed regions were analyzed by EDX to provide basic compositional data. When samples were prepared as for TEM, the information obtained with FIB/SEM is comparable, though at limited magnification, to that obtained from TEM. A combination of imaging, micro-manipulation, and compositional analysis appears of particular interest in the investigation of epithelial tissues, which are subjected to various endogenous and exogenous conditions affecting their structure and function. The FIB/SEM is a promising tool for an overall examination of epithelial tissue under normal, stressed, or pathological conditions.     

Role of the systems of DNA dark repair in determining bacterial and phage sensitivity to ultraviolet radiation in an ecological long-wave range]

A comparison has been made of sensitivity to far (254 nm), middle (300--315 nm) and near (315--400 nm) UV radiation of 12 strains of E. coli and 2 strains of B. subtilis differing in DNA dark repair (DR) capability. The mechanisms controlled by uvrA, uvrB, polA, recA, lon, and lexA genes are very effective in cells, irradiated by far and middle UV, but by 15--70% less effective in those irradiated by near UV. As the unirradiated bacteria poorly repair the near UV damaged phages (T7, lambda, SPPI), the low bacterial DR level after UV irradiation seems to be due to the unrepairable photoproduct formation in DNA.     

The applicability of acetylcholinesterase and glutathione S-transferase in Daphnia magna toxicity test

The most commonly used toxicity test worldwide is the acute Daphnia magna test. The relevance of acetylcholinesterase (AChE) and glutathione S-transferase (GST) activity in D. magna exposed to chromium, cadmium, and diazinon was evaluated in connection with this standard test. We found no link between enzyme activities and immobility. Concentrations of Cr(6+) up to 280 microg/L had no effect on AChE and GST activities, while 20% immobility was observed. At concentrations of 20-25 microg/L of Cd(2+) AChE activity was increased by about 50%. The effect of diazinon on both enzymes was insignificant up to concentrations that caused 27% immobility. Consequently, while the use of AChE and GST activities is recommended when the mode of action of chemicals is studied, the value of these biomarkers in routine acute toxicity tests is limited because the relationship between enzyme activities and immobility of D. magna exposed to different chemicals is unclear.     

Teaching cardiovascular physiology with equivalent electronic circuits in a practically oriented teaching module

Here, we report on a new tool for teaching cardiovascular physiology and pathophysiology that promotes qualitative as well as quantitative thinking about time-dependent physiological phenomena. Quantification of steady and presteady-state (transient) cardiovascular phenomena is traditionally done by differential equations, but this is time consuming and unsuitable for most undergraduate medical students. As a result, quantitative thinking about time-dependent physiological phenomena is often not extensively dealt with in an undergraduate physiological course. However, basic concepts of steady and presteady state can be explained with relative simplicity, without the introduction of differential equation, with equivalent electronic circuits (EECs). We introduced undergraduate medical students to the concept of simulating cardiovascular phenomena with EECs. EEC simulations facilitate the understanding of simple or complex time-dependent cardiovascular physiological phenomena by stressing the analogies between EECs and physiological processes. Student perceptions on using EEC to simulate, study, and understand cardiovascular phenomena were documented over a 9-yr period, and the impact of the course on the students' knowledge of selected basic facts and concepts in cardiovascular physiology was evaluated over a 3-yr period. We conclude that EECs are a valuable tool for teaching cardiovascular physiology concepts and that EECs promote active learning.     

New noncovalent inhibitors of penicillin-binding proteins from penicillin-resistant bacteria

Background

Penicillin-binding proteins (PBPs) are well known and validated targets for antibacterial therapy. The most important clinically used inhibitors of PBPs β-lactams inhibit transpeptidase activity of PBPs by forming a covalent penicilloyl-enzyme complex that blocks the normal transpeptidation reaction; this finally results in bacterial death. In some resistant bacteria the resistance is acquired by active-site distortion of PBPs, which lowers their acylation efficiency for β-lactams. To address this problem we focused our attention to discovery of novel noncovalent inhibitors of PBPs.

Methodology/Principal Findings

Our in-house bank of compounds was screened for inhibition of three PBPs from resistant bacteria: PBP2a from Methicillin-resistant Staphylococcus aureus (MRSA), PBP2x from Streptococcus pneumoniae strain 5204, and PBP5fm from Enterococcus faecium strain D63r. Initial hit inhibitor obtained by screening was then used as a starting point for computational similarity searching for structurally related compounds and several new noncovalent inhibitors were discovered. Two compounds had promising inhibitory activities of both PBP2a and PBP2x 5204, and good in-vitro antibacterial activities against a panel of Gram-positive bacterial strains.

Conclusions

We found new noncovalent inhibitors of PBPs which represent important starting points for development of more potent inhibitors of PBPs that can target penicillin-resistant bacteria.     

Changes in the major circulation vessel capacity and their role in forming the venous return shifts under the effect of catecholamines

The study relates to characteristics of the major circulation vessel capacity and their part in forming the venous return shifts under the effect of catecholamines. In anesthetized cats, using the developed technique of controlled experiment enabling to stabilize the blood flow in the circulation arterial segment, fulfilling of pressor responses to i. v. administration of noradrenaline, adrenaline was found to increase the venous return, on the average, by 40% by means of changes in the major circulation vessel capacity (its venous segment, mainly). About 5% of the blood volume seems to become mobilized in the animal organism.     

Nerve injury affects the capillary supply in rat slow and fast muscles differently

The goal of this study was to determine the acute effects of permanent denervation on the length density of the capillary network in rat slow soleus (SOL) and fast extensor digitorum longus (EDL) muscles and the effect of short-lasting reinnervation in slow muscle only. Denervation was performed by cutting the sciatic nerve. Both muscles were excised 2 weeks later. Reinnervation was studied 4 weeks after nerve crush in SOL muscle only. Capillaries and muscle fibres were visualised by triple immunofluorescent staining with antibodies against CD31 and laminin and with fluorescein-labelled Griffonia (Bandeira) simplicifolia lectin. A recently developed stereological approach allowing the estimation of the length of capillaries adjacent to each individual fibre (Lcap/Lfib) was employed. Three-dimensional virtual test grids were applied to stacks of optical images captured with a confocal microscope and their intersections with capillaries and muscle fibres were counted. Interrelationships among capillaries and muscle fibres were demonstrated with maximum intensity projection of the acquired stacks of optical images. The course of capillaries in EDL seemed to be parallel to the fibre axes, whereas in SOL, their preferential direction deviated from the fibre axes and formed more cross-connections among neighbouring capillaries. Lcap/Lfib was clearly reduced in denervated SOL but remained unchanged in EDL, although the muscle fibres significantly atrophied in both muscle types. When soleus muscle was reinnervated, capillary length per unit fibre length was completely restored. The physiological background for the different responses of the capillary network in slow and fast muscle is discussed. This study was supported by the Slovenian Research Agency and the Ministry of Education, Youth and Sport of the Czech Republic (KONTAKT grant no. 19/2005).