Zoonotic coronaviruses were discovered in the 1960s. Since then pathogenic human coronaviruses were identified beginning with the discovery of SARS-CoV in 2002. With the recent detection of SARS-CoV-2, there are now seven human coronaviruses. Those that cause mild diseases are the 229E, OC43, NL63 and HKU1, and the pathogenic species are SARS-CoV, MERS-CoV and SARS-CoV-2 Coronaviruses (order Nidovirales, family Coronaviridae, and subfamily Orthocoronavirinae) are spherical (125nm diameter), and enveloped with club-shaped spikes on the surface giving the appearance of a solar corona. Within the helically symmetrical nucleocapsid is the large positive sense, single stranded RNA. Of the four coronavirus genera (a,b,g,d), human coronaviruses (HCoVs) are classified under a-CoV (HCoV-229E and NL63) and b-CoV (MERS-CoV, SARS-CoV, HCoVOC43 and HCoV-HKU1). SARS-CoV-2 is a b-CoV and shows fairly close relatedness with two bat-derived CoV-like coronaviruses, bat-SL-CoVZC45 and bat-SL-CoVZXC21. Even so, its genome is similar to that of the typical CoVs. SARS-CoV and MERS-CoV originated in bats, and it appears to be so for SARS-CoV-2 as well. The possibility of an intermediate host facilitating the emergence of the virus in humans has already been shown with civet cats acting as intermediate hosts for SARS-CoVs, and dromedary camels for MERS-CoV. Human-to-human transmission is primarily achieved through close contact of respiratory droplets, direct contact with the infected individuals, or by contact with contaminated objects and surfaces. The coronaviral genome contains four major structural proteins: the spike (S), membrane (M), envelope (E) and the nucleocapsid (N) protein, all of which are encoded within the 3’ end of the genome. The S protein mediates attachment of the virus to the host cell surface receptors resulting in fusion and subsequent viral entry. The M protein is the most abundant protein and defines the shape of the viral envelope. The E protein is the smallest of the major structural proteins and participates in viral assembly and budding. The N protein is the only one that binds to the RNA genome and is also involved in viral assembly and budding. Replication of coronaviruses begin with attachment and entry. Attachment of the virus to the host cell is initiated by interactions between the S protein and its specific receptor. Following receptor binding, the virus enters host cell cytosol via cleavage of S protein by a protease enzyme, followed by fusion of the viral and cellular membranes. The next step is the translation of the replicase gene from the virion genomic RNA and then translation and assembly of the viral replicase complexes. Following replication and subgenomic RNA synthesis, encapsidation occurs resulting in the formation of the mature virus. Following assembly, virions are transported to the cell surface in vesicles and released by exocytosis.

Glass ionomer cement (GIC) has the unique fluoride release property and able to form ionic bond with tooth structure. However, the brittleness of the material results in low hardness. In the present study, a new approach in utilization of local waste materials as fillers for improvement of hardness of GIC is reported. The synthesized wollastonite and mine-silica by-product were individually incorporated into commercial GIC and the Vickers hardness were evaluated. The results shown that the incorporation of 1 % wollastonite into GIC gave ~ 6 % increment in hardness compared to the control GIC (66.53HV ± 7.37 versus 62.66HV ± 2.98) but not for the mine-silica. Thus, wollastonite could be a potential material to be utilized as fillers in dental restorative composite.

INTRODUCTION: We aimed to determine the risk factors associated with abdominal obesity (AO) in suburban adolescents. METHODS: This cross-sectional study included adolescents aged 15-17 years from five randomly selected secondary schools in the Hulu Langat district of Selangor state, Malaysia. Waist circumference (WC) was measured at the midpoint between the lower margin of the last palpable rib and the top of the iliac crest. Information on sociodemographic data, dietary habits, physical activity levels and duration of sleep was obtained via interviewer-administered questionnaires. Participants' habitual food intake was determined using a 73-item Food Frequency Questionnaire. RESULTS: Among 832 participants, 56.0% were girls; 48.4% were Malay, 40.5% Chinese, 10.2% Indian and 0.8% of other ethnic groups. Median age and WC were 16 (interquartile range [IQR] 15-16) years and 67.9 (IQR 63.0-74.6) cm, respectively. Overall prevalence of AO (> 90th percentile on the WC chart) was 11.3%. A higher proportion (22.4%) of Indian adolescents were found to have AO compared with Malay and Chinese adolescents. Logistic regression analysis showed that female gender (adjusted odds ratio [OR] 7.064, 95% confidence interval [CI] 2.087-23.913; p = 0.002), Indian ethnicity (adjusted OR 10.164, 95% CI 2.182-47.346; p = 0.003), irregular meals (adjusted OR 3.193, 95% CI 1.043-9.774; p = 0.042) and increasing body mass index (BMI) (adjusted OR 2.867, 95% CI 2.216-3.710; p < 0.001) were significantly associated with AO. CONCLUSION AO was common among Malaysian adolescents. Female gender, Indian ethnicity, irregular meals and increasing BMI were significant risk factors.
Adolescent ; Body Mass Index ; Cross-Sectional Studies ; Feeding Behavior ; Female ; Humans ; Malaysia ; epidemiology ; Male ; Obesity, Abdominal ; epidemiology ; therapy ; Odds Ratio ; Pediatric Obesity ; epidemiology ; therapy ; Prevalence ; Risk Factors ; Suburban Population ; Surveys and Questionnaires ; Waist Circumference