Vitamin D status and latent tuberculosis infection : a preliminary study in a group of healthy Mexican agricultural workers

Vitamin D metabolites are important in the regulation of bone and calcium homeostasis, but also have a more ubiquitous role in the regulation of cell differentiation and immune function. Severely low circulating 25-dihydroxyvitamin D [25(OH)D] concentrations have been associated with the onset of active tuberculosis (TB) in immigrant populations, although the association with latent TB infection (LTBI) has not received much attention. A previous study identified the prevalence of LTBI among a sample of Mexican migrant workers enrolled in Canada's Seasonal Agricultural Workers Program (SA WP) in the Niagara Region of Ontario. The aim of the present study was to determine the vitamin D status of the same sample, and identify if a relationship existed with LTBI. Studies of vitamin D deficiency and active TB are most commonly carried out among immigrant populations to non-endemic regions, in which reactivation of LTBI has occurred. Currently, there is limited knowledge of the association between vitamin D deficiency and LTBI. Entry into Canada ensured that these individuals did not have active TB, and L TBI status was established previously by an interferon-gamma release assay (IGRA) (QuantiFERON-TB Gold In-Tube®, Cellestis Ltd., Australia). Awareness of vitamin D status may enable individuals at risk of deficiency to improve their nutritional health, and those with LTBI to be aware of this risk factor for disease. Prevalence of vitamin D insufficiency among the Mexican migrant workers was determined from serum samples collected in the summer of 2007 as part of the cross sectional LTBI study. Samples were measured for concentrations of the main circulating vitamin D metabolite, 25(OH)D, with a widely used 1251 250HD RIA (DiaSorin Inc.®, Stillwater, MN), and were categorized as deficient «37.5 nmoI/L), insufficient (>37.5 nmollL, < 80 nmol/L) or sufficient (2::80 nmoI/L). Fisher's exact tests and t tests were used to determine if vitamin D status (sufficiency or insufficiency) or 25(OH)D concentrations significantly differed by sex or age categories. Predictors of vitamin D insufficiency and 25(OH)D concentrations were taken from questionnaires carried out during the previous study, and analyzed in the present study using multiple regression prediction models. Fisher's exact test and t test was used to determine if vitamin D status or 25(OH)D concentration differed by LTBI status. Strength of the relationship between interferongamma (IFN-y) concentration (released by peripheral T cells in response to TB antigens) and 25(OH)D concentration was analyzed using a Spearman correlation. Out of 87 participants included in the study (78% male; mean age 38 years), 14 were identified as LTBI positive but none had any signs or symptoms of TB reactivation. Only 30% of the participants were vitamin D sufficient, whereas 68% were insufficient and 2% were deficient. Significant independent predictors of lower 25(OH)D concentrations were sex, number of years enrolled in the SA WP and length of stay in Canada. No significant differences were found between 25(OH)D concentrations and LTBI status. There was a significant moderate correlation between IFN-y and 25(OH)D concentrations ofLTBI-positive individuals. The majority of participants presented with Vitamin D insufficiency but none were severely deficient, indicating that 25(OH)D concentrations do not decrease dramatically in populations who temporarily reside in Canada but go back to their countries of origin during the Canadian winter. This study did not find a statistical relationship between low levels of vitamin D and LTBI which suggests that in the presence of overall good health, lower than ideal levels of 2S(OH)D, may still be exerting a protective immunological effect against LTBI reactivation. The challenge remains to determine a critical 2S(OH)D concentration at which reactivation is more likely to occur.

Effects of dietary restraint and oral contraceptives on bone strength and bone turnover in young women

ABSTRACT Introduction The purpose of this study was to assess specific osteoporosis-related health behaviours and physiological outcomes including daily calcium intake, physical activity levels, bone strength, as assessed by quantitative ultrasound, and bone turnover among women between the ages of 18 and 25. Respective differences on relevant study variables, based on dietary restraint and oral contraceptive use were also examined. Methods One hundred women (20.6 ± 0.2 years of age) volunteered to participate in the study. Informed written consent was obtained by all subjects prior to participation. The study and all related procedures were approved by the Brock University Research Ethics Board. Body mass, height, relative body fat, as well as chest, waist and hip circumferences were measured using standard procedures. The 10-item restrained eating subscale of the Dutch Eating Behaviour Questionnaire (DEBQ) was used to assess dietary restraint (van Strien et al., 1986). Daily calcium intake was assessed by the Rapid Assessment Method (RAM) (Hertzler & Frary 1994). Weekly physical activity was documented by the 4-item Godin Leisure-Time Exercise Questionnaire (Godin & Shephard 1985). Bone strength was determined from the speed of sound (SOS) as measured by QUS (Sunlight 7000S). SOS measurements (m/s) were taken of the dominant and non-dominant sides of the distal one third of the radius and the mid-shaft of the tibia. Resting blood samples were collected from all subjects between 9am and 12pm, in order to evaluate the impact of lifestyle factors on biochemical markers of bone turnover. Blood was collected during the early follicular phase of the menstrual cycle (approximately days 1-5) for all subjects. Samples were centrifliged and the serum or plasma was aliquoted into separate tubes and stored at -80°C until analysis. The bone formation markers measured were Osteocalcin (OC), bone specific alkaline phosphatase (BAP) and 25-OH vitamin D. The bone resorption markers measured were the carboxy (CTx) and amino (NTx) terminal telopeptides of type-I collagen crosslinks. All markers were assessed by ELISA. Subjects were divided into high (HDR) and low dietary restrainers (LDR) based on the median DEBQ score, and also into users (BC) and non-users (nBC) of oral contraceptives. A series of multiple one way ANOVA's were then conducted to identify differences between each set of groups for all relevant variables. A two-way ANOVA analysis was used to explore significant interactions between dietary restraint and use of oral contraceptives while a univariate follow-up analysis was also performed when appropriate. Pearson Product Moment Correlations were used to determine relationships among study variables. Results HDR had significantly higher BMI, %BF and circumference measures but lower daily calcium intake than LDR. There were no significant differences in physical activity levels between HDR and LDR. No significant differences were found between BC and nBC in body composition, calcium intake and physical activity. HDR had significantly lower tibial SOS scores than LDR in both the dominant and non-dominant sites. The post-hoc analysis showed that within the non-birth control group, the HDR had significantly lower tibial SOS scores of bone strength when compared to the LDR but Aere were no significant differences found between the two dietary restraint groups for those currently on birth control. HDR had significantly lower levels of OC than LDR and the BC group had lower levels of BAP than the nBC group. Consistently, the follow-up analysis revealed that within those not on birth control, subjects who were classified as HDR had significantly (f*<0.05) lower levels of OC when compared with LDR but no significant differences were observed in bone turnover between the two dietary restraint groups for those currently on birth control. Physical activity was not correlated with SOS scores and bone turnover markers possibly due to the low physical activity variability in this group of women. Conclusion This is the first study to examine the effects of dietary restraint on bone strength and turnover among this population of women. The most important finding of this study was that bone strength and turnover are negatively influenced by dietary restraint independent of relative body fat. In general, the results of the present thesis suggest that dietary restraint, oral contraceptive use, as well as low daily calcium intake and low physical activity levels were widespread behaviours among this population of college-aged women. The young women who were using dietary restraint as a strategy to lose weight, and thus were in the HDR group, despite their higher relative body fat and weight, had lower scores of bone strength and lower levels of markers of bone turnover compared to the low dietary restrainers. Additionally, bone turnover seemed to be negatively affected by oral contraceptives, while bone strength, as assessed by QUS, seemed unaffected by their use in this population of young women. Physical activity (weekly energy expenditure), on the other hand, was not associated with either bone strength or bone tiimover possibly due to the low variability of this variable in this population of young Canadian women.

Bone speed of sound, biochemical markers of bone turnover and IGF-1 in competetive synchronized swimmers

The purpose of this study was to compare bone speed of sound (SOS) measured by quantitative ultrasound, circulating levels of IGF- 1 and biochemical markers of bone turnover in pre- (Pr) and post-menarcheal (Po) synchronized swimmers (SS) and controls (NS). Seventy participants were recruited: 8 PrSS, 22 PoSS, 20 PrNS, and 20 PoNS. Anthropometric measures of height, weight, skeletal maturity and percent body fat were taken, and dietary intake evaluated using 24-hour recall. Bone SOS was measured at the distal radius and mid-tibia and blood samples analyzed for IGF-1, osteocalcin, NTx, and 25-OH vitamin D. Results demonstrated maturational effects on bone SOS, IGF-1 and bone turnover (p<0.05), with no differences observed between SS and NS. Main effects were observed for a reduced caloric intake in SS compared to NS (p<0.05). Therefore, SS does not offer additive affects on bone strength but imparts no adverse affects to skeletal health in these athletes.

Bone speed of sound in overweight and normal-weight girls and adolescents

Over the last two decades, the prevalence of obesity in the general population has been steadily increasing. Obesity is a major issue in scientific research because it is associated with many health problems, one of which is bone quality. In adult females, adiposity is associated with increased bone mineral density, suggesting that there is a protective effect of fat on bone. However, the association between adiposity and bone strength during childhood is not clear. Thus, the purpose of this study was to compare bone strength, as reflected by speed of sound (SOS), of overweight and obese girls and adolescents with normal-weight age-matched controls. Data from 75 females included normal-weight girls (G-NW; body fat:::; 25%; n = 21), overweight and obese girls (GOW; body fat ~ 28%; n = 19), normal-weight adolescents (A-NW, body fat:::; 25%; n = 13) and overweight and obese adolescents (A-OW; body fat ~ 28%; n = 22). Nutrition was assessed with a 24-hour recall questionnaire and habitual physical activity was measured for one week using accelerometry. Using quantitative ultrasound (QUS; Sunlight Omnisense™), bone SOS was measured at the distal radius and mid-tibia. No differences were found between groups in daily total energy, calcium or vitamin D intake. However, all groups were below the recommended daily calcium intake of 1300 mg (Osteoporosis Canada, 2008). Adolescents were significantly less active than girls (14.7 ± 0.6 vs. 6.3 ± 0.6% active for G and A, respectively). OW accumulated significantly less minutes of moderate-to-very vigorous physical activity per day (MVPA) than NW in both age groups (114 ± 6 vs. 57 ± 5 min/day for NW and OW, i respectively). Girls had significantly lower radial SOS (3794 ± 87 vs. 3964 ± 64 mls for G-NW and A-NW, respectively), and tibial SOS (3678 ± 86 vs. 3878 ± 52 mls for G-NW and A-NW, respectively) than adolescents. Radial SOS was similar in the two adiposity groups within each age group. However, tibial SOS was lower in the two overweight groups (3601 ± 75 mls vs. 3739 ± 134 mls for G-OW and A-OW, respectively) compared with the age-matched normal-weight controls. Body fat percentage negatively correlated with tibial SOS in the study sample as a whole (r = -0.30). However, when split into groups, percent bo~y fat correlated with tibial SOS only in the A-OW group (r = -0.53). MVPA correlated with tibial SOS (r = 0.40), once age was partialed out. In conclusion, in contrast withthe higher bone strength characteristic of obese adult women, overweight and obese girls and adolescents are characterized by low tibial bone strength, as assessed with QUS. The differences between adiposity groups in tibial SOS may be at least partially due to the reduced weight-bearing physical activity levels in the overweight girls and adolescents. However, other factors, such as hormonal influences associated with high body fat may also playa role in reducing bone strength in overweight girls. Further research is required to reveal the mechanisms causing low bone strength in overweight and obese children and adolescents.

Does Bracing affect Bone Health in Females with adolescent Idiopathic Scoliosis?

This study examined the bone mineral content (BMC) in young women with Adolescent Idiopathic Scoliosis (AIS), treated with a brace (27.9 ±21.6 months, for 18.0±5.4 h/d) during adolescence (AIS-B, n = 15, 25.6 ±5.8 yrs), versus women with AIS but no treatment (AIS-NB, n = 15, 24.0 ±4.0 yrs), and women without AIS (C, n = 19, 23.5 ±3.8 yrs). After controlling for lean body mass, calcium and vitamin D daily intake, and strenuous physical activity, femoral neck BMC was lower in the AIS-B compared with AIS-NB and C (all p’s < .05). In summary, women with AIS, braced during their growing years are characterized by low lower limb BMC. However, the lack of a relationship between brace treatment duration and BMC, suggests that bracing was not the likely mechanism.

Dietary Intakes and Periodontal Outcomes After Sanative Therapy

Diet has an important role in the maintenance of oral health, but the relationship between diet and clinical outcomes following sanative therapy (ST) has not been investigated. Due to their antioxidant and anti-inflammatory properties, we hypothesized that periodontal patients with higher intakes of vitamin C, vitamin D, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) would have greater reductions in probing depth (PD) after ST. Patients completed the Block food frequency questionnaire, a supplement use questionnaire and had their serum 25-hydroxyvitamin D measured. There were no significant associations between intakes of vitamin C, vitamin D, EPA, DHA and PD. There were, however, negative associations between intakes of linoleic acid, α- linolenic acid or total vegetable intake and PD, as well as a positive association between the total omega-6/omega-3 ratio and PD (p < 0.05). Therefore, dietary intakes of essential fatty acids and vegetables may be important modulators of periodontal outcomes following ST.

Does bracing affect bone health in women with adolescent idiopathic scoliosis?

Purpose: Adolescent idiopathic scoliosis (AIS) is often associated with low bone mineral content and density (BMC, BMD). Bracing, used to manage spine curvature, may interfere with the growth-related BMC accrual, resulting in reduced bone strength into adulthood. The purpose of this study was to assess the effects of brace treatment on BMC in adult women, diagnosed with AIS and braced in early adolescence. Methods: Participants included women with AIS who: (i) underwent brace treatment (AIS-B, n = 15, 25.6 ± 5.8 yrs), (ii) underwent no treatment (AIS, n = 15, 24.0 ± 4.0 yrs), and (iii) a healthy comparison group (CON, n = 19, 23.5 ± 3.8 yrs). BMC and body composition were assessed using dual-energy X-ray absorptiometry. Differences between groups were examined using a oneway ANOVA or ANCOVA, as appropriate. Results: AIS-B underwent brace treatment 27.9 ± 21.6 months, for 18.0 ± 5.4 h/d. Femoral neck BMC was lower (p = 0.06) in AIS-B (4.54 ± 0.10 g) compared with AIS (4.89 ± 0.61 g) and CON (5.07 ± 0.58 g). Controlling for lean body mass, calcium and vitamin D daily intake, and strenuous physical activity, femoral neck BMC was statistically different (p = 0.02) between groups. A similar pattern was observed at other lower extremity sites (p < 0.05), but not in the spine or upper extremities. BMC and BMD did not correlate with duration of brace treatment, duration of daily brace wear, or overall physical activity. Conclusion: Young women with AIS, especially those who were treated with a brace, have significantly lower BMC in their lower limbs compared to women without AIS. However, the lack of a relationship between brace treatment duration during adolescence and BMC during young adulthood, suggests that the brace treatment is not the likely mechanism of the low BMC.

Diatoms as indicators of lake trophic status

Relationships between surface sediment diatom assemblages and lake trophic status were studied in 50 Canadian Precambrian Shield lakes in the Muskoka-Haliburton and southern Ontario regions. The purpose of this study was to develop mathematical regression models to infer lake trophic status from diatom assemblage data. To achieve this goal, however, additional investigations dealing with the evaluation of lake trophic status and the autecological features of key diatom species were carried out. Because a unifying index and classification for lake trophic status was not available, a new multiple index was developed in this study, by the computation of the physical, chemical and biological data from 85 south Ontario lakes. By using the new trophic parameter, the lake trophic level (TL) was determined: TL = 1.37 In[1 +(TP x Chl-a / SD)], where, TP=total phosphorus, Chl-a=chlorophyll-a and SD=Secchi depth. The boundaries between 7 lake trophic categories (Ultra-oligotrophic lakes: 0-0.24; Oligotrophic lakes: 0.241-1.8; Oligomesotrophic lakes: 1.813.0; Mesotrophic lakes: 3.01-4.20; Mesoeutrophic lakes: 4.21-5.4; Eutrophic lakes: 5.41-10 and Hyper-eutrophic lakes: above 10) were established. The new trophic parameter was more convenient for management of water quality, communication to the public and comparison with other lake trophic status indices than many of the previously published indices because the TL index attempts to Increase understanding of the characteristics of lakes and their comprehensive trophic states. It is more reasonable and clear for a unifying determination of true trophic states of lakes. Diatom specIes autecology analysis was central to this thesis. However, the autecological relationship of diatom species and lake trophic status had not previously been well documented. Based on the investigation of the diatom composition and variety of species abundance in 30 study lakes, the distribution optima of diatom species were determined. These determinations were based on a quantitative method called "weighted average" (Charles 1985). On this basis, the diatom species were classified into five trophic categories (oligotrophic, oligomesotrophic, mesotrophic, mesoeutrophic and eutrophic species groups). The resulting diatom trophic status autecological features were used in the regressIon analysis between diatom assemblages and lake trophic status. When the TL trophic level values of the 30 lakes were regressed against their fi ve corresponding diatom trophic groups, the two mathematical equations for expressing the assumed linear relationship between the diatom assemblages composition were determined by (1) uSIng a single regression technique: Trophic level of lake (TL) = 2.643 - 7.575 log (Index D) (r = 0.88 r2 = 0.77 P = 0.0001; n = 30) Where, Index D = (0% + OM% + M%)/(E% + ME% + M%); 4 (2) uSIng a' multiple regressIon technique: TL=4.285-0.076 0%- 0.055 OM% - 0.026 M% + 0.033 ME% + 0.065 E% (r=0.89, r2=0.792, P=O.OOOl, n=30) There was a significant correlation between measured and diatom inferred trophic levels both by single and multiple regressIon methods (P < 0.0001, n=20), when both models were applied to another 20 test lakes. Their correlation coefficients (r2 ) were also statistically significant (r2 >0.68, n=20). As such, the two transfer function models between diatoms and lake trophic status were validated. The two models obtained as noted above were developed using one group of lakes and then tested using an entirely different group of lakes. This study indicated that diatom assemblages are sensitive to lake trophic status. As indicators of lake trophic status, diatoms are especially useful in situations where no local trophic information is available and in studies of the paleotrophic history of lakes. Diatom autecological information was used to develop a theory assessing water quality and lake trophic status.

Office of the City Clerk, St. Catharines Records, 1928-1974, n.d.

The site of present-day St. Catharines was settled by 3000 United Empire Loyalists at the end of the 18th century. From 1790, the settlement (then known as "The Twelve") grew as an agricultural community. St. Catharines was once referred to Shipman's Corners after Paul Shipman, owner of a tavern that was an important stagecoach transfer point. In 1815, leading businessman William Hamilton Merritt abandoned his wharf at Queenston and set up another at Shipman's Corners. He became involved in the construction and operation of several lumber and gristmills along Twelve Mile Creek. Shipman's Corners soon became the principal milling site of the eastern Niagara Peninsula. At about the same time, Merritt began to develop the salt springs that were discovered along the river which subsequently gave the village a reputation as a health resort. By this time St. Catharines was the official name of the village; the origin of the name remains obscure, but is thought to be named after Catharine Askin Robertson Hamilton, wife of the Hon. Robert Hamilton, a prominent businessman. Merritt devised a canal scheme from Lake Erie to Lake Ontario that would provide a more reliable water supply for the mills while at the same time function as a canal. He formed the Welland Canal Company, and construction took place from 1824 to 1829. The canal and the mills made St. Catharines the most important industrial centre in Niagara. By 1845, St. Catharines was incorporated as a town, with the town limits extending in 1854. Administrative and political functions were added to St. Catharines in 1862 when it became the county seat of Lincoln. In 1871, construction began on the third Welland Canal, which attracted additional population to the town. As a consequence of continual growth, the town limits were again extended. St. Catharines attained city status in 1876 with its larger population and area. Manufacturing became increasingly important in St. Catharines in the early 1900s with the abundance of hydro-electric power, and its location on important land and water routes. The large increase in population after the 1900s was mainly due to the continued industrialization and urbanization of the northern part of the city and the related expansion of business activity. The fourth Welland Canal was opened in 1932 as the third canal could no longer accommodate the larger ships. The post war years and the automobile brought great change to the urban form of St. Catharines. St. Catharines began to spread its boundaries in all directions with land being added five times during the 1950s. The Town of Merritton, Village of Port Dalhousie and Grantham Township were all incorporated as part of St. Catharines in 1961. In 1970 the Province of Ontario implemented a regional approach to deal with such issues as planning, pollution, transportation and services. As a result, Louth Township on the west side of the city was amalgamated, extending the city's boundary to Fifteen Mile Creek. With its current population of 131,989, St. Catharines has become the dominant centre of the Niagara region. Source: City of St. Catharines website http://www.stcatharines.ca/en/governin/HistoryOfTheCity.asp (January 27, 2011)