Hypovitaminosis D in adolescent females--an analytical cohort study in the United Arab Emirates

BACKGROUND

Despite living in a sunny country, hypovitaminosis D is common in women of reproductive age in Al Ain, United Arab Emirates (UAE).

AIMS AND OBJECTIVES

To establish the prevalence of hypovitaminosis D in adolescent female Emirati nationals and its risk factors.

METHODS

This was an analytical prospective cohort study of 350 female Emirati nationals aged 11-18 years attending public schools in Al Ain. Socio-economic status, diet and amount of sun exposure were evaluated by face-to-face interviews. Serum total 25 (OH) vitamin D (D2 + D3) levels were measured by electrochemiluminescence assay. The prevalence of hypovitaminosis D was calculated and the association with risk factors analysed.

RESULTS

Data were complete for 293 girls. Only one girl [prevalence 0.3%, 95% confidence interval (CI) 0.01-1.9] had vitamin D sufficiency (serum vitamin D levels >75 nmol/L). Three girls (1.0%, 95% CI 0.2-2.9) had vitamin D insufficiency (50-75 nmol/L), 58 (19.8%, 95% CI 15.0-25.5) were deficient (27.5-50 nmol/L) and 231 (78.8%, 95% CI 68.9-89.6) had severe deficiency (<27.5 nmol/L). Serum vitamin D levels declined between the ages of 11 and 13 years before progressively rising until the age of 18 years but without regaining the levels they were at the age of 11. There was no statistically significant difference between the vitamin D status groups in age, body mass index, accommodation type, family income, percentage of surface area unexposed to the sun when outdoors, consumption of oily fish or total vitamin D intake.

CONCLUSION

The finding of a high prevalence of hypovitaminosis D in adolescent females in UAE is of serious concern for their health and that of their infants during their reproductive lives. Adolescent girls with a similar social and cultural background currently living in less sunny, industrialised countries might also be at risk.

Cellular bioenergetics, caspase activity and glutathione in murine lungs infected with influenza A virus

Inhibition of cellular respiration, oxidation of glutathione and induction of apoptosis have been reported in epithelial cells infected in vitro with influenza A virus (IAV). Here, the same biomarkers were investigated in vivo by assessing the lungs of BALB/c mice infected with IAV. Cellular respiration declined on day 3 and recovered on day 7 post-infection. For days 3-5, the rate (mean±SD) of respiration (µMO2min(-1)mg(-1)) in uninfected lungs was 0.103±0.021 (n=4) and in infected lungs was 0.076±0.025 (n=4, p=0.026). Relative cellular ATP (infected/uninfected) was 4.7 on day 2 and 1.07 on day 7. Intracellular caspase activity peaked on day 7. Cellular glutathione decreased by ≥10% on days 3-7. Lung pathology was prominent on day 3 and caspase-3 labeling was prominent on day 5. IAV infection was associated with suppression of cellular respiration, diminished glutathione, and induction of apoptosis. These functional biomarkers were associated with structural changes noted in infected mice.

Bioenergetics of murine lungs infected with respiratory syncytial virus

BACKGROUND

Cellular bioenergetics (cellular respiration and accompanying ATP synthesis) is a highly sensitive biomarker of tissue injury and may be altered following infection. The status of cellular mitochondrial O(2) consumption of the lung in pulmonary RSV infection is unknown.

METHODS

In this study, lung fragments from RSV-infected BALB/c mice were evaluated for cellular O(2) consumption, ATP content and caspase activity. The disease was induced by intranasal inoculation with the RSV strain A2 and lung specimens were analyzed on days 2-15 after inoculation. A phosphorescence O(2) analyzer that measured dissolved O(2) concentration as a function of time was used to monitor respiration. The caspase-3 substrate analogue N-acetyl-asp-glu-val-asp-7-amino-4-methylcoumarin (Ac-DEVD-AMC) was used to monitor intracellular caspases.

RESULTS

O(2) concentration declined linearly with time when measured in a sealed vial containing lung fragment and glucose as a respiratory substrate, revealing its zero-order kinetics. O(2) consumption was inhibited by cyanide, confirming the oxidation occurred in the respiratory chain. Cellular respiration increased by 1.6-fold (p<0.010) and ATP content increased by 3-fold in the first week of RSV infection. Both parameters returned to levels found in uninfected lungs in the second week of RSV infection. Intracellular caspase activity in infected lungs was similar to uninfected lungs throughout the course of disease.

CONCLUSIONS

Lung tissue bioenergetics is transiently enhanced in RSV infection. This energy burst, triggered by the virus or virus-induced inflammation, is an early biomarker of the disease and may be targeted for therapy.

Longitudinal study of vitamin D status in the 1st 6 months of life

Although hypovitaminosis D has been reported in the neonatal period and infancy, there is currently little information on the longitudinal changes in vitamin D status throughout early infancy.

AIM

To estimate, in Al Ain, UAE, the prevalence of vitamin D deficiency and longitudinal changes and risk factors in infants between birth and 6 months of age.

METHODS

Serum 25-OH-vitamin-D levels were measured after birth and 6 months later in 27 infants of mothers of Middle Eastern or Asian origin who were pregnant between the months of September and November 2007.

RESULTS

At delivery, mean (SD) maternal serum 25-OH-vitamin-D level was 35.5 nmol/L (24.7); five mothers (22%, 95% CI 0.7-43) had adequate serum levels (>50 mmol/L), 11 (48%, 95% CI 27-70) insufficient levels (25-50 nmol/L) and seven (30%, 95% CI 13-53) deficient (<25 nmol/L) levels. Serum 25-OH-vitamin-D levels were adequate in eight infants (30%, CI 14-50%), insufficient in 13 (48%, CI 28-60%) and deficient in six (22%, CI 8.5-42%). Despite recommendations, none had received any vitamin D supplementation since birth. Despite the high prevalence of hypovitaminosis D at birth and the lack of pharmacological supplementation, the number of infants with adequate levels at 6 months of age rose to 20 (87%, CI 66-97%). No infant had deficiency (CI 0-21%) and three (13%, CI 27-33%) had insufficiency. Adequate levels were detected in four infants who were partially breastfed [mean (SD) 108.5 (20.7) nmol/L] and in only 84% of the 19 exclusively breastfed infants [mean (SD) 96.2 (44.5) nmol/L] but the difference was not statistically significant. Although serum levels improved at 6 months, it occurred more slowly in exclusively breastfed infants.

CONCLUSION

In the absence of vitamin D supplementation, guidelines for vitamin D supplementation in infancy still need to be followed because the mechanisms for normalisation are not clearly understood.

Pilot study of sunlight exposure and vitamin D status in Arab women of childbearing age

Vitamin D deficiency is common in Arab women. In a pilot study we investigated the effect of sun exposure at recommended levels on the vitamin D status of Arab women. Eight healthy Arab women of childbearing age consented to expose their face, arms and hands for 15 minutes per day twice a week for 4 weeks within the privacy of their courtyard and to avoid changes in dietary vitamin D intake. Serum 25-hydroxyvitamin D [25(OH)] levels were measured pre- and post-intervention. Although vitamin D levels remained sub-optimal median serum 25(OH)D levels were significantly higher post-intervention (23.0 nmol/L) than pre-intervention (17.6 nmol/L). Extending sun exposure for more than 4 weeks should be investigated as part of strategies to improve vitamin D status in high-risk Arab women who lack outdoor sun exposure to the skin.

Toxicokinetics of aflatoxin in pregnant mice

Our objective was to study the toxicokinetics of aflatoxin (AF) in pregnant mice. Aflatoxin B1 (AFB1) was administered intraperitoneally (IP) to groups of pregnant mice in single doses of 20 mg/kg on gestation day (GD) 13 and orally at the same gestational age. Controls received (IP and oral) a proportionate volume of solvent only. Maternal blood was collected at 15, 30, 45, 60, 90, 120, and 150 minutes posttreatment. Their AFB1 contents were determined. Aflatoxin B1 concentrations following maternal exposure to AFB1 were highly correlated with time after exposure. The serum concentrations were predictable and the highest serum levels were seen immediately at 15 minutes in mice given AFs IP and at 30 minutes in those given it orally. The absorption was 5.0 microg/min and elimination was 3.0 microg/min. The toxicokinetics of AFB1 have been delineated. Aflatoxins are easily and rapidly absorbed both from the gastrointestinal tract (GI) tract and through the peritoneum.

Maternal vitamin D status throughout and after pregnancy

Prospective longitudinal study of vitamin D status and its risk factors in 75 pregnant women from early pregnancy until 6 months postpartum, by serial measurement of serum 25 (OH) vitamin D levels. The serum levels at booking were not significantly different between nationalities (p = 0.06), parity (p = 0.2), education levels (p = 0.4), dress code (p > 0.5), consumption of vitamin D fortified milk (p = 0.2) or, fatty fish (p = 0.5), sun-exposed body surface area (p = 0.3), weekly time exposed to the sun (p = 0.08) or the sun exposure index (p = 0.2). Vitamin D status progressively worsened as the proportion with adequate serum levels fell from 31% at the antenatal visit, to 23% after birth and 17%, 6 months later (p = 0.02). While 80% of mothers who were exclusively breast-feeding had low vitamin D levels 6 months after delivery, this occurred in only 67% of those partially breast-feeding (p = 0.6).

Current maternal-infant micronutrient status and the effects on birth weight in the United Arab Emirates

Micronutrient deficiencies exist among women of childbearing age in the United Arab Emirates but the effects of maternal micronutrient deficiency on fetal growth are not well documented. To investigate the association between micronutrients and birth weight, we measured maternal and cord blood micronutrients (vitamin A, C, D, and E) and ferritin in 84 term, singleton infants born to healthy Arab and South Asian women at Al-Ain hospital. Median serum ascorbic acid and 25-hydroxyvitamin D (25-OHD) concentrations were low in mothers and infants. In multivariate analysis, maternal serum 25-OHD correlated positively with birth weight while serum ferritin showed a negative correlation.

Higher prevalence of vitamin D deficiency in mothers of rachitic than nonrachitic children

Vitamin D deficiency [serum 25-hydroxyvitamin D <25 nmol/L (<10 ng/mL)] was identified in 92% of rachitic Arab children and 97% of their mothers compared with 22% of nonrachitic children and 52% of their mothers. There was a positive correlation between maternal and child vitamin D levels. We conclude that mothers of rachitic children should be investigated and treated for vitamin D deficiency.

Hypovitaminosis D and vitamin D deficiency in exclusively breast-feeding infants and their mothers in summer: a justification for vitamin D supplementation of breast-feeding infants

OBJECTIVE

To determine the prevalence of hypovitaminosis D in exclusively breast-feeding infants and their mothers in a community where maternal sunshine exposure is low.

STUDY DESIGN

Serum levels of calcium, phosphate, alkaline phosphatase, 25-hydroxy vitamin D (25-OHD), and intact parathyroid hormone were measured in 90 unsupplemented healthy term breast-feeding Arab/South Asian infants and their mothers in summer. Maternal dietary vitamin D intake was also estimated.

RESULTS

The median age of infants was 6 weeks. The median serum 25-OHD concentrations in mothers (8.6 ng/mL) and infants (4.6 ng/mL) were low, and 61% of the mothers and 82% of the 78 infants tested had hypovitaminosis D (serum 25-OHD <10 ng/mL). The infants with hypovitaminosis D had elevated serum alkaline phosphatase and a tendency to higher serum intact parathyroid hormone levels. The average daily maternal vitamin D intake from commercial milk was 88 IU.

CONCLUSIONS

Hypovitaminosis D is common in summer in exclusively breast-feeding infants and their mothers. The results provide justification for vitamin D supplementation of breast-feeding infants and mothers in the United Arab Emirates. Low vitamin D intake probably contributed to low maternal vitamin D status.

Diet, clothing, sunshine exposure and micronutrient status of Arab infants and young children

Vitamin C and D levels in Arab women and their newborn infants have been shown to be low. We investigated the prevalence of and risk factors for possible hypovitaminosis C and D in a convenience sample of 51 hospitalized children without clinical features of vitamin C or D deficiency. The mean age was 15.4 months. The serum vitamin C concentration was low in the mothers but normal in the children. Both mothers and children had low serum 25-hydroxyvitamin D (25-OHD) concentrations. Fifty per cent of the mothers and 22% of the infants and children had hypovitaminosis D (serum 25-OHD level < 25 nmol/l). Infants who received dietary vitamin D supplementation had a higher mean (SD) serum 25-OHD concentration than the unsupplemented group (62.5 (29.8) vs 38.5 (27.3), p = 001). Cutaneous light exposure in these children was poor. The children's serum 25-OHD concentration correlated with dietary vitamin D supplementation and maternal serum 25-OHD levels. The results suggest normal vitamin C status but a possible high prevalence of hypovitaminosis D in Arab children and their mothers in UAE. Health education to encourage greater sunshine exposure and improvement in maternal vitamin D stores and the availability of adequate vitamin D supplements would improve children's vitamin D status. The study indicates that hypovitaminosis D continues to be an important maternal and child health problem, despite the abundant sunshine.

Respiratory syncytial virus infection among hospitalized young children with acute lower respiratory illnesses in Al Ain, UAE

To establish the frequency and clinical pattern of Respiratory Syncytial virus (RSV) infection in the region, children under 3 years of age admitted for acute lower respiratory illness during two winter seasons of the years 1993-94 and 1994-95 were studied prospectively. Seventy two cases were diagnosed to have RSV infection among the 252 studied, representing 28.57% of these patients. The overall infection rate was 32.1% and 36.5% respectively for the two studied winter seasons. Among these children, 90% were under 12 months of age. A clinical diagnosis of sepsis and respiratory distress was entertained in five RSV positive cases and they were < 1 month of age. The clinical pattern of RSV infection included bronchiolitis in 58.3% of cases, bronchopneumonia (19.4%) and pneumonia (11.1%). RSV activity was detected throughout the year with predominance during cooler months with an associated relative humidity (RH) between 50-60%. These results indicate that RSV plays a significant etiologic role among ALRI in hospitalized infants and young children in the Oasis region of the UAE. Factors such as RH, environmental temperature and lifestyle probably play an additional role in our region for the maintenance and dissemination of infection around the year.