The shell of garden snail (Helix aspersa) is basically made of calcium carbonate. An attempt is made to convert calcium carbonate of garden snail shell to hydroxyapatite. The snail shell was found to decompose within 850 • C to all the carbonate phases. The calcined snail shells were then treated with acids followed by different chemicals in ammoniacal media maintaining proper stoichiometry to produce fine hydroxyapatite (HAP) as filter cake with a Ca/P molar ratio of 1•67. The dried HAP powder was extremely pure with a specific surface area of 15 m 2 /g. The different characterization techniques were adopted both for calcined snail shell and HAP synthesized by X-ray diffraction (XRD), thermal analysis (DTA/TGA), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The surface area and particle size of HAP powder prepared by chemical precipitation route, were also determined by BET and Malvern particle size analyser, respectively. The synthesized powder was soaked in stimulated body fluid (SBF) medium for various periods of time in order to evaluate its bioactivity. The changes of pH of SBF medium were measured. High bioactivity of prepared HAP powder due to the formation of apatite on its surface was observed.

Purposes: Dengue fever, a mosquito-borne viral disease, is a global public health burden affecting millions of people each year and over 40% of world populations are at risk of dengue. Therefore, prompt and accurate dengue diagnosis is inevitable for disease surveillance and for aiding disease management. In this study we report dengue virus (DENV) seroprevalence in Chittagong, Bangladesh along with clinical manifestation of dengue infections. Methods: All samples included in this study were selected based on dengue NS1-based diagnosis, clinical sign and symptoms were judged by expert clinical physicians and infecting DENV serotyping was done by RT-PCR. The blood cells (Platelet, Haematocrit, WBC etc) were analyzed using Haematology cell counter. Results: First, among the 112 DENV infected serum samples tested by RT-PCR, 42 were DENV positive where 76% samples had single DENV serotype infection and 24% were concurrently infected with two or more DENV serotypes, indicating that all four DENVs were present in a single dengue session in Chittagong, Bangladesh. Then, DENV4 was the most prevailed serotype, followed by DENV2, DENV1 and DENV3 in single DENV serotype infections. However, in almost 90% cases of concurrent multiple DENV infections DENV1 serotype was present. A detail analysis of clinical data clearly indicated that DENV1 and DENV2 resulted very similar patterns of clinical symptoms which were quite different from those caused by DENV3 and DENV4. For example, ache and pain were absent in DENV3 infection and diarrhea was absent in DENV4 infections. Furthermore, DENV3, both in single and concurrent multiple DENV infections, might increase dengue disease severity as observed highly reduced platelet counts along with increased WBC in patients infected with DENV3 serotype. Conclusion: All four DENV serotypes, both as single and concurrent multiple DENV infections, were present in single dengue session in Bangladesh. Despite having very similar sequences and structures all four DENVs might produce different disease spectra, ranging from classical dengue fever to dengue hemorrhagic fever. Concurrent multiple DENV infections could contribute increased dengue disease severity in dengue outbreaks in Bangladesh. Bioresearch Commu. 8(1): 1042-1048, 2022 (January)

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A novel attempt is made to convert the calcium carbonate skeleton of widely available garden snail shell (Helix aspersa) to hydroxyapatite based bioceramics. The snail shell was found to decompose within 850 0 C to all the carbonate phases. The calcined snail shells were then treated with acids followed by different chemicals in ammoniacal media maintaining proper stoichemetry to produce fine Hydroxyapatite (HAP) as filter cake with Ca/P molar ratio of 1.67. The dried HAP powder was extremely pure with specific surface area of 15m 2 /g. The different characterization techniques were adopted both for calcined snail shell and HAP synthesized like X-ray Diffraction (XRD), Thermal Analysis (DTA/ TGA), Fourier Transform Infra red Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). The surface area and the particle size, of the HAP powder prepared by chemical precipitation route, were also determined by BET and Malvern particle size analyzer respectively. The synthesized powder was soaked in stimulated body fluid (SBF) medium for various periods of time in order to evaluate its bioactivity. The changes of the pH of SBF medium were measured. High bioactivity of prepared HAP powder due to the formation of apatite on its surface was observed.

Dengue is a mosquito-borne viral disease in tropical and subtropical countries worldwide. Dengue disease is caused by four structurally similar but serologically distinct dengue virus serotypes (DENV1~4) [1][2][3]. Humans are the only known hosts of DENVs and the dengue disease spectra range from undifferentiated fever to severe hemorrhagic fever. Although the vast majority of people infected with DENVs remain asymptomatic, dengue is preliminary characterized by typical dengue fever, and in severe cases, DENV infection may result dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) [4]. The severe dengue, DHF, and DSS include leakage of vascular fluids, hemorrhagic manifestation, and shock accompanied by thrombocytopenia and abundant complement activation [5], and under such conditions, the patients need immediate hospitalization.The RNA genome of DENVs encodes only 10 proteins: The capsid protein (C-protein), pre-membrane protein (prM-protein), envelope protein (E-protein), and seven non-structural proteins (NS-protein) [6].