Course of Plasmodium infection studied using 2D-COS on human erythrocytes

BACKGROUND

The threat of malaria is still present in the world. Recognizing the type of parasite is important in determining a treatment plan. The golden routine involves microscopic diagnostics of Giemsa-stained thin blood smears, however, alternative methods are also constantly being sought, in order to gain an additional insight into the course of the disease. Spectroscopic methods, e.g., Raman spectroscopy, are becoming increasingly popular, due to the non-destructive nature of these techniques.

METHODS

The study included patients hospitalized for malaria caused by Plasmodium falciparum or Plasmodium vivax, in the Department of Infectious Diseases at the University Hospital in Krakow, Poland, as well as healthy volunteers. The aim of this study was to assess the possibility of using Raman spectroscopy and 2D correlation (2D-COS) spectroscopy in understanding the structural changes in erythrocytes depending on the type of attacking parasite. EPR spectroscopy and two-trace two-dimensional (2T2D) correlation was also used to examine the specificity of paramagnetic centres found in the infected human blood.

RESULTS

Two-dimensional (2D) correlation spectroscopy facilitates the identification of the hidden relationship, allowing for the discrimination of Raman spectra obtained during the course of disease in human red blood cells, infected by P. falciparum or P. vivax. Synchronous cross-peaks indicate the processes taking place inside the erythrocyte during the export of the parasite protein towards the cell membrane. In contrast, moieties that generate asynchronous 2D cross-peaks are characteristic of the respective ligand-receptor domains. These changes observed during the course of the infection, have different dynamics for P. falciparum and P. vivax, as indicated by the asynchronous correlation cross-peaks. Two-trace two-dimensional (2T2D) spectroscopy, applied to EPR spectra of blood at the beginning of the infection, showed differences between P. falciparum and P. vivax.

CONCLUSIONS

A unique feature of 2D-COS is the ability to discriminate the collected Raman and EPR spectra. The changes observed during the course of a malaria infection have different dynamics for P. falciparum and P. vivax, indicated by the reverse sequence of events. For each type of parasite, a specific recycling process for iron was observed in the infected blood.

Blood-stage antiplasmodial activity and oocyst formation-blockage of metallo copper-cinchonine complex

In the fight against malaria, the key is early treatment with antimalarial chemotherapy, such as artemisinin-based combination treatments (ACTs). However, Plasmodium has acquired multidrug resistance, including the emergence of P. falciparum strains with resistance to ACT. The development of novel antimalarial molecules, that are capable of interfering in the asexual and sexual blood stages, is important to slow down the transmission in endemic areas. In this work, we studied the ability of the mettalo copper-cinchonine complex to interfere in the sexual and asexual stages of Plasmodium. The tested compound in the in vitro assay was a cinchonine derivative, named CinCu (Bis[Cinchoninium Tetrachlorocuprate(II)]trihydrate). Its biological functions were assessed by antiplasmodial activity in vitro against chloroquine-resistant P. falciparum W2 strain. The mice model of P. berghei ANKA infection was used to analyze the antimalarial activity of CinCu and chloroquine and their acute toxicity. The oocyst formation-blocking assay was performed by experimental infection of Anopheles aquasalis with P. vivax infected blood, which was treated with different concentrations of CinCu, cinchonine, and primaquine. We found that CinCu was able to suppress as high as 81.58% of parasitemia in vitro, being considered a molecule with high antiplasmodial activity and low toxicity. The in vivo analysis showed that CinCu suppressed parasitemia at 34% up to 87.19%, being a partially active molecule against the blood-stage forms of P. berghei ANKA, without inducing severe clinical signs in the treated groups. The transmission-blocking assay revealed that both cinchonine and primaquine were able to reduce the infection intensity of P. vivax in A. aquasalis, leading to a decrease in the number of oocysts recovered from the mosquitoes' midgut. Regarding the effect of CinCu, the copper-complex was not able to induce inhibition of P. vivax infection; however, it was able to induce an important reduction in the intensity of oocyst formation by about 2.4 times. It is plausible that the metallo-compound also be able to interfere with the differentiation of parasite stages and/or ookinete-secreted chitinase into the peritrophic matrix of mosquitoes, promoting a reduction in the number of oocysts formed. Taken together, the results suggest that this compound is promising as a prototype for the development of new antimalarial drugs. Furthermore, our study can draw a new pathway for repositioning already-known antimalarial drugs by editing their chemical structure to improve the antimalarial activity against the asexual and sexual stages of the parasite.

Benthic foraminifera contribution to fjord modern carbon pools: A seasonal study in Adventfjorden, Spitsbergen

The aim of this study was to determine the amount of organic and inorganic carbon in foraminifera specimens and to provide quantitative data on the contribution of foraminifera to the sedimentary carbon pool in Adventfjorden. The investigation was based on three calcareous species that occur commonly in Svalbard fjords: Cassidulina reniforme, Elphidium excavatum and Nonionellina labradorica. Our results show that the species investigated did not contribute substantially to the organic carbon pool in Adventfjorden, because they represented only 0.37% of the organic carbon in the sediment. However, foraminiferal biomass could have been underestimated as it did not include arenaceous or monothalamous taxa. Foraminiferal carbonate constituted up to 38% of the inorganic carbon in the sediment, which supports the assumption that in fjords where non-calcifying organisms dominate the benthic fauna foraminifera are among the major producers of calcium carbonate and that they play crucial roles in the carbon burial process. The results presented in this study contribute to estimations of changes in foraminiferal carbon levels in contemporary environments and could be an important reference for palaeoceanographic studies.

IN VIVO PERFORMANCE OF THE EXPERIMENTAL CHITOSAN BASED BONE SUBSTITUTE--ADVANCED THERAPY MEDICINAL PRODUCT. A STUDY IN SHEEP

When evaluating a novel bone substitute material, advanced in vivo testing is an important step in development and safety affirmation. Sheep seems to be a valuable model for human bone turnover and remodeling activity. The experimental material composed with the stem cells is an advanced therapy medicinal product (acc. to EC Regulation 1394/2007). Our research focuses on histological differences in bone formation (guided bone regeneration--GBR) in sheep maxillas after implantation of the new chitosan/tricalcium phosphate/alginate (CH/TCP/Alg) biomaterial in comparison to the commercially available xenogenic bone graft and a/m enhanced with the stem cells isolated from the adipose tissue. Twelve adult female sheep of BCP synthetic line, weighing 60-70 kg were used for the study. The 11 mm diameter defects in maxilla bone were prepared with a trephine bur under general anesthesia and then filled with the bone substitute materials: CH/TCP/Alg, BioOss Collagen, Geistlich AG (BO), CH/TCP/Alg composed with the stem cells (CH/S) or left just with the blood clot (BC). Inbreeding cycle of the animals terminated at 4 months after surgery. Dissected specimens of the maxilla were evaluated histologically and preliminary under microtomography. Histological evaluation showed early new bone formation observed around the experimental biomaterial and commercially available BO. There were no features of purulent inflammation and necrosis, or granulomatous inflammation. Microscopic examination after 4 months following the surgery revealed trabecular bone formation around chitosan based bone graft and xenogenic material with no significant inflammatory response. Different results--no bone recreation were observed for the negative control (BC). In conclusion, the tested materials (CH/TCP/Alg and BO) showed a high degree of biocompatibility and some osteoconductivity in comparison with the control group. Although the handiness, granules size and setting time of CHffCP/Alg may be refined for future clinical tests. The relevant beneficial influence of using the adipose derived stem cells in GBR was not confirmed in this model.

Cytotoxicity Evaluation and Crystallochemical Analysis of a Novel and Commercially Available Bone Substitute Material

BACKGROUND

Alloplastic biomaterials are an alternative for autologous transplants and xenografts in oral surgery and dental implantology. These non-immunogenic and resorbable materials are becoming the basis for complete and predictable guided bone regeneration in many cases. The chemical composition of a great majority of them is based on calcium phosphate salts. In vivo performance is often variable.

OBJECTIVES

The objective was to evaluate the biological and chemical properties of an experimental bone substitute material.

MATERIAL AND METHODS

The present research focuses on the cytotoxicity comparison and physiochemical characterization of two biomaterials: a novel chitosan/tricalcium phosphate/alginate composite (CH/TCP/Ag) and a commercially available synthetic bone graft made of HA (60%) and βTCP (40%) (HA/TCP). The materials were evaluated according to PN-EN ISO 10993 Biological evaluation of medical devices i.e. cytotoxicity on mouse fibroblasts (L929) and, in addition, tests on human osteoblasts (hFOB1.19) and human osteosarcoma (MG-63) were conducted. The crystallochemical analysis was performed using the X-ray powder diffraction method. The Bruker-AXS D8 Advance diffractometer (Karlsruhe, Germany) was used to collect diffractograms.

RESULTS

The tested materials showed a close resemblance in chemical composition and a considerable differentiation in cytotoxic response.

CONCLUSIONS

The novel composite demonstrated a high degree of cytocompatibility, which is promising in future clinical trials.

Chitosan and composite microsphere-based scaffold for bone tissue engineering: evaluation of tricalcium phosphate content influence on physical and biological properties

In the hereby presented work the authors describe a technique of high-compression-resistant biodegradable bone scaffold preparation. The methodology is based on the agglomeration of chitosan (CH) and chitosan/β-tricalcium phosphate (CH/TCP) microspheres and represents a novel approach to 3D matrices design for bone tissue engineering application. The materials were prepared from high deacetylation degree chitosan. The authors describe the method for scaffold fabrication, essential properties of the materials manufactured and the influence of various TCP concentrations on material morphology, mechanical properties (for dry and hydrated materials) and preliminary study on the interaction between CH or CH/TCP scaffolds and within cultured MG-63 osteoblast-like cells. The properties of the obtained materials were significantly affected by the calcium phosphate content, which had a particular influence on the granule microstructure, size distribution and inner biomaterial pore size. The water uptake ability was found to be lower for the materials enriched with the inorganic phase and tended to decrease with the increasing calcium phosphate concentration. The evaluation of mechanical properties has revealed that scaffolds produced with the usage of granule-based technology display a potential to be used as a load-bearing material since the Young's modulus values were limited to the range of 200-500 MPa for dry materials and 15-20 MPa for the hydrated state of the scaffolds. The cell number, identified in three time points (48 h, 7 and 14 days) by Pico Green assay, was lower for the materials enriched with inorganic phase (75 % of control), however cell distribution, when compared to CH only biomaterial, was acknowledged as steadier on the surface of the material containing the highest calcium phosphate concentration.

Bone regeneration potential of the new chitosan-based alloplastic biomaterial

Over the last few years, alloplastic bone substitute materials are raising much interest as an alternative to autologic transplants and xenogenic materials especially in oral surgery. These non-immunogenic and completely resorbable biomaterials are becoming the basis for complete and predictable guided bone regeneration in many cases. The objective of our research was to evaluate the dynamics of bone formation in rats' skulls after implantation of the new chitosan/tricalcium phosphate/alginate biomaterial in comparison to the commercially available alloplastic bone graft. A total of 45 adult male rats weighing 300-400 g were used for the study. The 85-mm-diameter defects in calvaria bone were prepared with a trephine bur, and then filled with the bone substitute materials: chitosan/tricalcium phosphate/alginate or easy-graft Classic (Degradable Solutions AG) (EA) or left just with the blood clot. Animals were sacrificed at 1 and 3 months for histological, histomorphometrical and micro-tomographic evaluations. Histological evaluation at 1 month showed early new bone formation, observed around the experimental biomaterial (CH/TCP/Alg). There were no features of purulent inflammation and necrosis or granulomatous inflammation. Microscopic examination after 3 months following the surgery revealed trabecular bone formation around chitosan-based bone graft with no significant inflammatory response. Less satisfactory and differing results were observed for the commercially available EA and control blood clot. The tested material (chitosan) showed a high degree of biocompatibility and osteoconductivity in comparison with the control groups. Additionally, it seemed to be a "user-friendly" material for oral surgeons.

Formation and preclinical evaluation of a new alloplastic injectable bone substitute material

Alloplastic bone substitute materials are raising some more interest as an alternative for autologic transplants and xenogenic materials especially in oral surgery over the last few years. These non-immunogenic and completely resorbable biomaterials are the basis for complete and predictable guided bone regeneration. In the majority of cases, such a material is chosen because of its convenient application by surgeons. The main objective of our project was to design and fabricate an osteoconductive, injectable and readily tolerable by human tissues biomaterial for guided bone regeneration. For this purpose, a self-setting composite consisting of chitosan/tricalcium phosphate microparticles and sodium alginate was made. The material obtained was characterized by microsphere and agglomerate morphology and microstructure. Its features relating to setting time and mechanical properties were precisely investigated. Our material was also evaluated according to PN-EN ISO 10993 Biological evaluation of medical devices, i.e., the in vitro tests for genotoxicity and cytotoxicity were conduced. Then, the following examinations were performed: subchronic systemic toxicity, skin sensitization, irritation and delayed-type hypersensitivity and local effects after implantation. The material tested showed a high degree of cytocompatibility, fulfilled the requirements of International Standards and seemed to be a "user friendly" material for oral surgeons.

Impaired vitamin B12 metabolic status in healthcare workers occupationally exposed to nitrous oxide

BACKGROUND

Previous studies demonstrated inactivation of vitamin B12 by nitrous oxide (N(2)O). The intraoperative exposure to N(2)O was shown to induce megaloblastic anaemia and myelopathy in subjects with subclinical vitamin B12 deficiency. In contrast, no data concerning the influence of occupational exposure to N(2)O on vitamin B12 metabolic status are available to date. In the present study, the vitamin B12 status in operating theatre personnel was assessed in relation to the extent of exposure.

METHODS

Ninety-five operating theatre nurses with the history of exposure to N(2)O and 90 unexposed counterparts were examined. Vitamin B12 and folic acid were measured by immunoassay. Total homocysteine (tHcy), an indicator of impaired vitamin B12 metabolism, was determined by high performance liquid chromatography. N(2)O concentration was monitored by adsorption gas chromatography and mass spectrometry.

RESULTS

No significant differences were found between both groups with respect to haematological parameters and folic acid. However, subjects exposed to N(2)O presented with lower vitamin B12 [372.8 (12.1) vs 436.8 (13.2) pmol litre(-1), P<0.001] and higher tHcy [11.2 (0.5) vs 8.9 (0.5) micromol litre(-1), P=0.006]. The changes in vitamin B12 status were aggravated in subjects exposed to N(2)O in concentrations substantially exceeding occupational exposure limit (180 mg m(-3)) [vitamin B12: 341.9 (17.7) vs 436.8 (13.2) pmol litre(-1), P=0.006; tHcy: 12.9 (0.7) vs 8.9 (0.5) micromol litre(-1), P=0.047].

CONCLUSIONS

Exposure to N(2)O in healthcare workers is associated with alterations of vitamin B12 metabolic status, the extent of which depends on the level of exposure.

Diffuse scattering and ordering in the short-range modulated paraelectric phase of sodium nitrite, NaNO2

The incommensurately modulated antiferroelectric phase of sodium nitrite, NaNO2, transforms at TN = 437.7 K to the short-range modulated paraelectric phase. The apparently discontinuous phase transition is accompanied by characteristic changes in the diffraction pattern. Contrary to the well known modulated structures with sharp satellite reflections, the diffraction pattern of a short-range modulated structure contains diffuse satellite reflections. The short-range modulated crystal structure of the paraelectric phase of sodium nitrite has been analysed by the Reverse Monte Carlo (RMC) simulation of X-ray diffuse scattering. The crystal structure of sodium nitrite may be regarded as consisting of [Na+NO_2^{-}]∞ rows running along the polar b axis. One can expect long fragments of rows with uniform polarity The assumption that single [Na+NO_2^-]∞ rows are polar with uniform polarity proved to be a convenient approximation which is in good agreement with the observed diffraction pattern. The distribution of (+)- and (−)-[Na+NO_2^-]∞ polar rows crossing the (010) plane of short-range modulated NaNO2 revealed by RMC shows nanodomains consisting of distorted fragments of a sinusoidally modulated crystal structure. The size of the nanodomains and the degree of order in paraelectric NaNO2 decreases with temperature.

[Hearing impairment in the plastics industry workers exposed to styrene and noise]

Styrene exerts ototoxic effect in animals, and the combined exposure to this solvent and noise produces a synergistic effect relative to the isolated exposure to noise. However, there is a lack of reliable evidence that chronic occupational exposure to styrene is ototoxic to humans. Neither has been documented its additive effect with noise. The present study was aimed to assess hearing impairment and the risk of hearing loss in workers exposed to both styrene and noise. The study group included 72 male workers occupationally exposed to styrene in the plastics industry. The results were compared with two control groups, matched by age, gender and personal traits: one group composed of 82 male workers employed in a printing house and exposed only to noise at the levels almost twice as high as those observed in the group exposed to styrene and noise, and the other consisted of 65 male workers exposed neither to solvents nor to noise at workplace. In the group exposed to styrene and noise, significantly increased average hearing loss, as compared to both control groups, was found at all frequencies (1-8 kHz). The risk of hearing loss in the group exposed to styrene and noise was seven times higher (RR: 6.6; 3.0-15.9) than in the non-exposed group, and four times higher (RR: 4.0; 1.8-9.1) than in when workers exposed only to noise. However, no relationship could be observed between the amount of styrene exposure and hearing impairment, taking account of the confounding effect of noise and age. The results of the study suggest that the exposure to solvent mixtures with styrene as a basic component may exert additional, to noise, adverse effect on the auditory organ.

[Assessment of hearing impairment in workers exposed to mixtures of organic solvents in the paint and lacquer industry]

Clinical and experimental studies indicate a possible harmful effect of chemicals, especially organic solvents, on the hearing system. In combined exposure to noise and solvents, very common in industry, it is most likely that a synergetic action of these factors enhances the traumatising effect of exposure to noise. The aim of this study was to assess the incidence and the risk of hearing impairment in 117 paint and lacquer factory workers exposed to a mixture of organic solvents. An analysis of organic solvent mixtures reveals that xylene and ethyl acetate are their major components whose concentrations depend on individual workposts. The control group consisted of 76 workers exposed to noise exceeding, Threshold Limit Value and 125 healthy subjects exposed neither to noise nor to solvents in their occupational setting. Pure tone audiometry revealed the highest hearing thresholds in workers exposed to solvents, lower thresholds in those exposed to noise, and the lowest ones in the non-exposed individuals. Hearing loss was found in 30% of workers exposed to organic solvents, in 20% of noise-exposed subjects, and in only 6% of non-exposed subjects. The comparison of relative risk values also indicated significantly enhanced probability of hearing impairment in workers of the paint and lacquer factory (9.6; 3.2-25.6), which is even more strongly pronounced than in the group of subjects exposed to noise (4.2; 1.2-13.2). An analysis of hearing impairment risk in particular frequencies suggests that organic solvents may damage the inner ear in much greater extent than noise. The results of the study show that exposure to organic solvents may create a significant risk of hearing impairment. Therefore, further steps should be taken to include the exposed population into effective preventive programmes.

Concentrations of anaesthetic gases in hospital operating theatres

Occupational exposure to anaesthetic gases (halothane, forane and nitrous oxide) was assessed in hospitals located in Lódź and its satellite towns. Individual dosimetry and stationary sampling methods were employed. The samples of air from workplaces were analysed by gas chromatography with mass detection or flow ionisation (halothane, forane) and by infra-red spectroscopy method (nitrous oxide). The concentrations of halothane and accompanying substances (ethanol, isopropanol and diethyl ether) indicate that Polish OELs were met in the majority of the hospitals. As Polish hygiene standards for forane and nitrous oxide are no available, the concentration values were compared with Swedish and German OELs. The comparison revealed that forane concentrations did not exceed Swedish OEL but nitrous oxide did exceed German maximum allowable levels.