SIGLEC-4 (MAG) Antagonists: From the Natural Carbohydrate Epitope to Glycomimetics

Siglec-4, also known as myelin-associated glycoprotein (MAG), is a member of the siglec (sialic acid-binding immunoglobulin-like lectins) family. MAG binds with high preference to sialic acids α(2-3)-linked to D-galactose. Although the involvement and relevance of its sialic acid binding activity is still controversial, it could be demonstrated that interactions of MAG with sialylated gangliosides play an important role in axon stability and regeneration. In this article we describe in detail our current understanding of the biological role and the carbohydrate specificity of siglec-4. Furthermore, this review compiles the intensive research efforts leading from the identification of the minimal oligosaccharide binding epitope in gangliosides via micromolar oligosaccharide mimics to the development of small molecular weight and more drug-like sialic acid derivatives binding with low nanomolar affinities. Such compounds will be useful to elucidate MAG's biological functions, which are currently not fully understood

Anti SARS-CoV-2 seroprevalence in Zanzibar in 2021 before the Omicron wave

OBLECTIVES: For Tanzania, including Zanzibar, the development of the COVID-19 pandemic has remained unclear since the reporting of cases was suspended during 2020/21. Our study was the first to analyze data on COVID-19 seroprevalence in the Zanzibari population before the Omicron variant wave began in late 2021. DESIGN: During August through October 2021, representative cross-sectional data were collected from randomly selected households in 120 wards of the two main islands, Unguja and Pemba. Participants voluntarily provided blood samples to test their sera for antibodies against SARS-CoV-2 using a semiquantitative enzyme-linked immunosorbent assay (ELISA). RESULTS: 58.9% of the 2051 sera analysed were positive, without significant differences between Unguja and Pemba or between rural and urban areas. The results were in agreement with observations from other sub-Saharan African countries. CONCLUSIONS: The antibody levels observed were most likely due to previous infections with SARS-CoV-2, since vaccination was generally not available before the survey. Therefore, this study offers the first insights into how many Zanzibari had COVID-19 before the Omicron variant emerged. Furthermore, it provides an appropriate basis for a follow-up survey addressing how this seroprevalence has influenced susceptibility to the Omicron variants, given the use of harmonized methodologies

Design, Response Rates, and Population Characteristics of a Cross-Sectional Study in Zanzibar, Tanzania

BACKGROUND: Data on nutritional status and correlates of noncommunicable diseases are scarce for resource-poor settings in sub-Saharan countries. With the scope of a project, “Access to Food and Nutrition Status of the Zanzibari Population,” data for investigating public health questions were collected using proven measurement and laboratory standards. OBJECTIVE: The present study aims at providing a descriptive overview of recruitment approaches, standardization, quality control measures, and data collection, with special attention to the design, responses, and participant characteristics of the overall project. METHODS: A cross-sectional study across 80 randomly selected Shehias (wards) was conducted in 2013 in Unguja Island, Zanzibar. Examinations included all members living in 1 household, face-to-face interviews and anthropometric measurements (weight, height, mid-upper arm circumference, waist and hip circumference, and body composition) were assessed for all household members, blood pressure was taken from participants older than 2 years, and biosamples (urine and blood) from eligible household members were collected. Data collected from the core sample included sociodemographic data, nutritional status, and medical history (hypertension). Physical activity data was collected from a subsample of children between 3 and 16 years of age. RESULTS: A total of 1314 participants (mean age 23.6 ± 18.9 years, 54.54% female) completed all anthropometric measurements and were included in the analysis. Out of which, 98.40% (1293/1314) completed the household member’s questionnaire, 93.32% (1229/1314) participants older than 2 years completed blood pressure measurements, and 64.31% (845/1314) blood samples were collected from participants older than 5 years. Underweight prevalence for the total study population was 36.53% (480/1314) with the highest prevalence in children under 14 years. Overweight and obesity was highest among females with the prevalence of 7.61% (100/1314) and 6.62% (87/1314), respectively; obesity was rare among male participants. CONCLUSIONS: The study provides valuable data to investigate the interplay of socioeconomic, demographic, environmental, physiological, and behavioral factors in the development of diet-related disorders in a representative sample of the Zanzibari population

Exploring Food Access and Sociodemographic Correlates of Food Consumption and Food Insecurity in Zanzibari Households

Rapid growth of the Zanzibari population and urbanization are expected to impact food insecurity and malnutrition in Zanzibar. This study explored the relationship between food access (FA) and sociodemographic correlates with food consumption score and food insecurity experience scale. Based on cross-sectional data of 196 randomly selected households, we first investigated the association between sociodemographic correlates and Food Consumption Score (FCS) and Food Insecurity Experience Scale using multilevel Poisson regression. Secondly, the role of FA in these associations was investigated by interaction with the respective correlates. About 65% of households had poor food consumption, and 32% were severely food-insecure. Poor FA was more prevalent in households with poor food consumption (71%). Polygamous households and larger households had a higher chance for severe food insecurity. In the interaction with FA, only larger households with poor FA showed a higher chance for severe food insecurity. In households having no vehicle, good FA increased the chance of having acceptable FCS compared to poor FA. By contrast, urban households with good FA had a twofold chance of acceptable FCS compared to rural household with poor FA. Poor FA, poor food consumption and food insecurity are challenging; hence, facilitating households’ FA may improve the population’s nutrition situation

Association between cardiometabolic risk factors and body mass index, waist circumferences and body fat in a Zanzibari cross-sectional study

OBJECTIVES: To determine the prevalence of obesity indices (body mass index (BMI), waist circumference (WC), body fat per cent (BF%)) and cardiometabolic risk factors. To investigate the association between obesity indices and cardiometabolic risk factors in a Zanzibari population. DESIGNS:Cross-sectional study. SETTINGS: Participants randomly selected from 80 Shehias (wards) in Unguja, Zanzibar in 2013. PARTICIPANTS: A total of 470 participants between 5 and 95 years were examined. Data on socioeconomic status, area of residence, anthropometry and venous blood were collected. Associations between obesity indices and cardiometabolic risk factors were investigated using multilevel logistic regression analyses in two steps: first, each obesity indicator was tested independently; second, all indicators combined in one model were tested for their association with cardiometabolic risk factors. RESULTS: The proportion of overweight/obese individuals was 26.4%, high WC (24.9%) and high BF% (31.1%). Cardiometabolic risk factors with highest prevalence of abnormal values included hypertension (24.5%), low high-density lipoprotein cholesterol (HDL-C) (29.4%), high low-density lipoprotein cholesterol (LDL-C) (21.3%) and high glycated haemoglobin (HbA1c) (19.1%). Obesity and hypertension increased with age, and were most prevalent in participants aged 45 years and above. Low HDL-C was most prevalent among participants aged ≥18 to <45 years, while high LDL-C was more prevalent in those above 45 years. High WC and high BF% were associated with high levels of LDL-C (OR=2.52 (95% CI 1.24 to 5.13), OR=1.91 (95% CI 1.02 to 3.58), respectively). Additionally, BMI and WC were associated with high levels of HbA1c (OR=2.08 (95% CI 1.15 to 3.79), OR=3.01 (95% CI 1.51 to 6.03), respectively). In the combined regression model, WC was associated with higher chances for hypertension (OR=2.62 (95% CI 1.14 to 6.06)) and for high levels of HbA1c (OR=2.62 (95% CI 1.12 to 6.15)). CONCLUSION: High BMI, WC and BF% were strongly associated with hypertension, with individuals with high WC being twice more likely to have hypertension; this calls for early and effective screening strategies for this study population

Anthropometric and Biochemical Predictors for Hypertension in a Cross-Sectional Study in Zanzibar, Tanzania

BACKGROUND: Aim of this study was to describe the proportion of hypertension among Zanzibari of different age-groups and to detect possible correlates of this non-communicable disease. METHODS: In 2013 a cross-sectional survey was conducted in Unguja Island, Zanzibar. A total of 235 randomly selected households, including 1,229 (2 to 95 years) eligible study participants, were examined. Association between objectively assessed obesity markers, salt intake and hypertension were investigated. Estimates of 24 h sodium and potassium excretion from a single morning spot urine specimen were calculated and used as surrogate for salt intake. The association between overweight/obesity and hypertension in different age-groups was assessed in multilevel logistic regression models. Further associations between salt intake and hypertension were analyzed. RESULTS: Measures of systolic and diastolic blood pressure as well as proportion of overweight/obesity and hypertension both increased with age. Overweight and obesity were significantly associated with hypertension in adults. Moreover, thinness seems to be associated with hypertension as well. We observed a significantly reduced chance of hypertension for higher urinary sodium-to-potassium compared to a lower ratio in children. CONCLUSION: Overweight/obesity and hypertension were highly prevalent (>47% of adults >40 years are overweight or obese and >69% are hypertensive in the same age group) in our sample. Weight status was confirmed as a correlate of high blood pressure in our sample from Zanzibar, Tanzania. To early and effectively prevent related severe cardiovascular outcomes, screening strategies but also monitoring strategies are required for this population