Vitamin D deficiency induces the excitation/inhibition brain imbalance and the proinflammatory shift

Vitamin D₃ is among the major neurosteroids whose role in developing and adult brain is intensively studied now. Its active form 1,25(OH)₂D₃ regulates the expression and functioning of a range of brain-specific proteins, which orchestrate the neurotransmitter turnover, neurogenesis and neuroplasticity. Despite numerous studies of the vitamin D role in normal and pathological brain function, there is little evidence on the mechanisms of alterations in excitatory and inhibitory neurotransmission under vitamin D deficiency (VDD). Using the animal model we characterized the dysfunction of excitatory and inhibitory neurotransmission under alimentary VDD. The shift between unstimulated and evoked GABA release under VDD was largely reversed after treatment of VDD, whereas the impairments in glutamatergic system were only partially recovered after 1-month vitamin D₃ supplementation. The increase of the external glutamate level and unstimulated GABA release in brain nerve terminals was associated with intensified ROS production and higher [Ca²⁺]_i in presynapse. The negative allosteric modulation of presynaptic mGlu7 receptors significantly enhanced exocytotic GABA release, which was decreased under VDD, thereby suggesting the neuroprotective effect of such modulation of inhibitory neurotransmission. Synaptic plasma membranes and cytosolic proteins contribute to the decreased stimulated release of neurotransmitter, by being the crucial components, whose functional state is impaired under VDD. The critical changes with synaptic vesicles occurred at the docking step of the process, whereas malfunctioning of synaptic cytosolic proteins impacted the fusion event foremost. The decreased amplitude of exocytosis was inherent for non-excitable cells as well, as evidenced by lower platelet degranulation. Our data suggest the presynaptic dysfunction and proinflammatory shift as the early events in the pathogenesis of VDD-associated disorders and provide evidences for the neuroprotective role of vitamin D₃.

Effect of Vitamin D on Cognitive Functions in Older Adults: 24-Week Follow-Up Study

The purpose of this study is to assess the effect of vitamin D replacement on cognitive function in older adults. A total of 560 patients who underwent comprehensive geriatric assessment including Global cognitive assessment, Basic Activities of Daily Living (BADL), and Instrumental Activities of Daily Living (IADL) twice in 6-month period were retrospectively reviewed. Oral cholecalciferol was replaced to patients with vitamin D deficiency routinely. In baseline cognitive scores, BADL-IADL scores were lower in the severe deficiency group than in the deficiency and adequate groups (P < .05). With regard to the relation between changes in cognitive functions, BADL-IADL scores on the 6-month versus baseline, no difference was determined in patients with and without dementia (P > .05). Vitamin D replacement may not improve cognitive performance in older adults, even if vitamin D is raised to adequate level, suggesting that longer term replacement therapy may be needed to improve cognitive function.

Vitamin D deficiency and its health effects

Vitamin D3 cholecalciferol is produced from its cholesterol precursors in the skin under the influence of ultraviolet calc. Its subsequent hydroxylation in the liver and kidneys leads to the formation of its most active metabolite calcitriol, which plays one of the key roles in the management of calcium phosphate metabolism. However, it also has the ability to regulate the function of a number of cells and tissues that express the vitamin D receptor. The most widespread method to evaluate the status of vitamin D in the body is to measure serum levels of its meta-bolite 25 hydroxyvitamin D - 25 (OH) D. Optimal values range between 75-125 nmoll / l. Its deficit is widespread in the human population worldwide and has a significant impact on the prevalence of metabolic bone diseases. Its deficiency may support the dysfunction of many other body systems. Ensuring optimal levels of vitamin D in the popula-tion is a challenge not only for health care and especially for government administration.

An overview of type 2 diabetes and importance of vitamin D3-vitamin D receptor interaction in pancreatic β-cells

One significant health issue that plagues contemporary society is that of Type 2 diabetes (T2D). This disease is characterised by higher-than-average blood glucose levels as a result of a combination of insulin resistance and insufficient insulin secretions from the β-cells of pancreatic islets of Langerhans. Previous developmental research into the pancreas has identified how early precursor genes of pancreatic β-cells, such as Cpal, Ngn3, NeuroD, Ptf1a, and cMyc, play an essential role in the differentiation of these cells. Furthermore, β-cell molecular characterization has also revealed the specific role of β-cell-markers, such as Glut2, MafA, Ins1, Ins2, and Pdx1 in insulin expression. The expression of these genes appears to be suppressed in the T2D β-cells, along with the reappearance of the early endocrine marker genes. Glucose transporters transport glucose into β-cells, thereby controlling insulin release during hyperglycaemia. This stimulates glycolysis through rises in intracellular calcium (a process enhanced by vitamin D) (Norman et al., 1980), activating 2 of 4 proteinases. The rise in calcium activates half of pancreatic β-cell proinsulinases, thus releasing free insulin from granules. The synthesis of ATP from glucose by glycolysis, Krebs cycle and oxidative phosphorylation plays a role in insulin release. Some studies have found that the β-cells contain high levels of the vitamin D receptor; however, the role that this plays in maintaining the maturity of the β-cells remains unknown. Further research is required to develop a more in-depth understanding of the role VDR plays in β-cell function and the processes by which the beta cell function is preserved.

Efficacy of high dose Vitamin D supplementation in improving serum 25(OH)D among migrant and non migrant population: a retrospective study

BACKGROUND

Higher dose of vitamin D supplementation 50000 IU is required for those whose serum 25(OH)D levels are 50 nmol/L and below. The increment in serum 25(OH)D though not significantly affected by race, sex or age it is negatively correlated to the baseline 25(OH)D concentration. This study investigated whether the mean increase in serum 25(OH)D will be higher among participants with lower baseline 25(OH)D levels and whether the duration of supplementation has an influence on the serum 25(OH)D achieved.

METHODS

A clinical audit of patients' medical records from a community health centre in Melbourne for the period 01.01.2010 to 31-12.2012 was undertaken. Paired sample t test was used to determine difference in pre and post dose serum 25(OH)D. Simple and multiple linear regressions were used to examine the association between the difference in pre and post dose serum 25(OH)D and duration of supplementation and baseline serum 25(OH)D, adjusting for socio-demographic factors.

RESULTS

A total of 205 patients were included in the study. Mean difference in serum 25(OH)D was highest 52.8 nmol/L (95 % CI: 46.63-58.92) among those whose serum 25(OH)D was below 25 nmol/L at baseline. Baseline 25(OH)D alone accounted for 13.7 % of variance in the effect size (F(2, 202) = 16.0. p < 0.001), with the effect size significantly higher among participants with a baseline 25(OH)D level of 25-49 nmol/L (β = 11.93, 95 % CI: 0.48, 23.40, p < 0.05). Mean serum 25(OH)D difference was highest, 47.53 nmol/L (95 % CI: 40.95-54.11) when measured within 3 months of supplementation. Duration of supplementation explained 2.9 % of the variance in the effect size (F (1, 203) = 6.11, p < 0.05) and there was an inverse relationship between the length of supplementation and mean pre and post supplementation serum 25(OH)D difference (β = -1.45, 95 % CI: -2.62, -0.29, p = 0.014).

CONCLUSION

Following 50000 IU vitamin D3 for 12 months mean serum 25(OH)D increase was highest among those whose baseline serum 25(OH)D was lower. Migrants especially dark-skinned are at a high risk for vitamin D deficiency in Australia. High dose vitamin D3 50000 IU (cholecalciferol) is effective in achieving sufficient serum 25(OH)D among these populations who tend to have lower baseline serum 25(OH)D.

The nonskeletal effects of vitamin D3 and the threshold limit associated with the risk of health complications

OBJECTIVE

To evaluate the threshold limit of vitamin D3 associated with the risk of nonskeletal health complications in humans.

BACKGROUND

Vitamin D3 deficiency is primary caused by a reduced sun exposure, consequent limiting of vitamin D3 production in the skin, and low intake of food with this vitamin.

METHODS

Ninety-two adults (25-95 years old) were admitted to III. Internal clinic or examined in outpatient department of The University hospital in Bratislava. Vitamin D3 levels were determined using electrochemical luminescence immunoassay. The least square method for the results processing was used.

RESULTS

Vitamin D3 level 16 ng/ml may be threshold limit for the risk of hypertension, ischaemic heart disease, renal insufficiency and diabetes mellitus. A higher occurrence of the observed diseases was in female and male patients with vitamin D3 levels<16 ng/ml.The highest increase of occurrence of diabetes mellitus in women for vitamin D3<16 ng/ml (160%) compared to vitamin D3≥16 ng/ml (40%) was observed. Concerning the men, the highest increase refers to ischaemic heart disease (67%).

CONCLUSION

The limit value of vitamin D3, 16 ng/ml, confirmed the association between vitamin D3 insufficiency and the presence of hypertension, ischaemic heart disease, renal insufficiency and diabetes mellitus. Its relation to age, sex and other variables was detected (Tab. 1, Fig. 5, Ref. 27).

Maternal vitamin D supplementation during pregnancy prevents vitamin D deficiency in the newborn: an open-label randomized controlled trial

OBJECTIVE

To determine whether maternal vitamin D supplementation, in the vitamin D deficient mother, prevents neonatal vitamin D deficiency.

DESIGN

Open-label randomized controlled trial.

SETTING

Metropolitan Melbourne, Australia, tertiary hospital routine antenatal outpatient clinic.

PARTICIPANTS

Seventy-eight women with singleton pregnancies with vitamin D deficiency/insufficiency (serum 25-OH Vit D < 75 nmol/l) at their first antenatal appointment at 12-16-week gestation were recruited.

INTERVENTION

Participants were randomized to vitamin D supplementation (2000-4000 IU cholecalciferol) orally daily until delivery or no supplementation.

MAIN OUTCOME MEASURES

The primary outcome was neonatal serum 25-OH vit D concentration at delivery. The secondary outcome was maternal serum 25-OH vit D concentration at delivery.

RESULTS

Baseline mean maternal serum 25-OH vit D concentrations were similar (P = 0·9) between treatment (32 nmol/l, 95% confidence interval 26-39 nmol/l) and control groups (33 nmol/l, 95% CI 26-39 nmol/l). Umbilical cord serum 25-OH vit D concentrations at delivery were higher (P < 0·0001) in neonates of treatment group mothers (81 nmol/l, 95% CI; 70-91 nmol/l) compared with neonates of control group mothers (42 nmol/l, 95% CI; 34-50 nmol/l) with a strongly positive correlation between maternal serum 25-OH Vit D and umbilical cord serum 25-OH vit D concentrations at delivery (Spearman rank correlation coefficient 0·88; P < 0·0001). Mean maternal serum 25-OH Vit D concentrations at delivery were higher (P < 0·0001) in the treatment group (71 nmol/l, 95% CI; 62-81 nmol/l) compared with the control group (36 nmol/l, 95% CI; 29-42 nmol/l).

CONCLUSION

Vitamin D supplementation of vitamin D deficient pregnant women prevents neonatal vitamin D deficiency.

Tissue content of vitamin D3 and 25-hydroxy vitamin D3 in minipigs after cutaneous synthesis, supplementation and deprivation of vitamin D3

Information regarding the endogenous storages of vitamin D3 after cutaneous vitamin D synthesis compared to oral vitamin D3 supplementation is sparse. Furthermore it is not known whether vitamin D3 can be stored for later use during periods of shortages of vitamin D3. To investigate the endogenous storages of vitamin D3 two studies were carried out in Göttingen minipigs. In study 1 one group of minipigs (n=2) was daily exposed to UV light corresponding to 10-20 min of midday sun and another group (n=2) of pigs were fed up to 60 μg vitamin D3/day corresponding to 3.7-4.4 μg/kg body weight. Study 1 demonstrated that daily UV-exposure of minipigs stimulated the cutaneous synthesis of vitamin D3 and resulted in increasing serum vitamin D3 and 25-hydroxy vitamin D3, but also carcasses containing vitamin D3 and 25-hydroxy vitamin D3. The vitamin D3 content in adipose tissue from the UV-exposed minipigs was 150-260 ng/g and the content was 90-150 ng/g in the orally supplemented minipigs. In study 2, minipigs were UV-exposed daily for 49 days. Subsequently, one group (n=2) was fed a vitamin D-free diet and another group (n=2) was dosed daily with 13C-labeled vitamin D3. The concentrations of vitamin D3 and 25-hydroxy vitamin D3 in serum and skin- and subcutaneous adipose tissue biopsies were repeatedly monitored. Vitamin D3 and 25-hydroxy vitamin D3 were eliminated from the skin and the adipose tissue after UV-exposure was ceased. Supplementation of 13C-vitamin D3 did not seem to affect the decline in the endogenous vitamin D3 in the adipose tissue formed during UV-exposure.

Dietary Vitamin D3 Restriction Exacerbates Disease Pathophysiology in the Spinal Cord of the G93A Mouse Model of Amyotrophic Lateral Sclerosis

Background

Dietary vitamin D₃ (D₃) restriction reduces paw grip endurance and motor performance in G93A mice, and increases inflammation and apoptosis in the quadríceps of females. ALS, a neuromuscular disease, causes progressive degeneration of motor neurons in the brain and spinal cord.

Objective

We analyzed the spinal cords of G93A mice following dietary D₃ restriction at 2.5% the adequate intake (AI) for oxidative damage (4-HNE, 3-NY), antioxidant enzymes (SOD2, catalase, GPx1), inflammation (TNF-α, IL-6, IL-10), apoptosis (bax/bcl-2 ratio, cleaved/pro-caspase 3 ratio), neurotrophic factor (GDNF) and neuron count (ChAT, SMI-36/SMI-32 ratio).

Methods

Beginning at age 25 d, 42 G93A mice were provided food ad libitum with either adequate (AI;1 IU D₃/g feed; 12 M, 11 F) or deficient (DEF; 0.025 IU D₃/g feed; 10 M, 9 F) D₃. At age 113 d, the spinal cords were analyzed for protein content. Differences were considered significant at P ≤ 0.10, since this was a pilot study.

Results

DEF mice had 16% higher 4-HNE (P = 0.056), 12% higher GPx1 (P = 0.057) and 23% higher Bax/Bcl2 ratio (P = 0.076) vs. AI. DEF females had 29% higher GPx1 (P = 0.001) and 22% higher IL-6 (P = 0.077) vs. AI females. DEF males had 23% higher 4-HNE (P = 0.066) and 18% lower SOD2 (P = 0.034) vs. AI males. DEF males had 27% lower SOD2 (P = 0.004), 17% lower GPx1 (P = 0.070), 29% lower IL-6 (P = 0.023) and 22% lower ChAT (P = 0.082) vs. DEF females.

Conclusion

D₃ deficiency exacerbates disease pathophysiology in the spinal cord of G93A mice, the exact mechanisms are sex-specific. This is in accord with our previous results in the quadriceps, as well as functional and disease outcomes.

Update on common nutritional disorders of captive reptiles

Nutritional disorders of captive reptiles remain very common despite the increasing knowledge about reptile husbandry and nutrition. Many nutritional disorders are diagnosed late in the disease process; often secondary complications, such as pathologic fractures in reptiles suffering from nutritional secondary hyperparathyroidism have occurred. Therefore, every attempt should be made to educate reptile owners and keepers about the proper care and dietary needs of reptiles under their care because all nutritional disorders seen in captive reptiles are preventable.

[Correction by vitamin D3 of disturbed metabolism in patients with diabetes mellitus types 1 and 2]

Vitamin D deficiency is an increasingly recognized public health problem of population as a whole and against a background of different chronic diseases. The aim of the study was to determine the status of D-vitamin, mineral, carbohydrate and lipid metabolism in patients with diabetes 1 and 2 types and in the case of vitamin D3 application. The data on the impact of vitamin D3 deficiency on mineral, carbohydrate and lipid metabolism, as well as on pancreatic beta-cells functional activity in patients with diabetes mellitus types 1 and 2 are presented. Certain reasons that lead to the disruption of vitamin D3 metabolism in patients with diabetes mellitus and the results of vitamin D3 application in clinics are discussed.

Efficacy and safety of weekly alendronate plus vitamin D₃ 5600 IU versus weekly alendronate alone in Korean osteoporotic women: 16-week randomized trial

Vitamin D (vit-D) is essential for bone health, although many osteoporosis patients have low levels of 25-hydroxy-vit-D [25(OH)D]. This randomized, open-label study compared the effects of once weekly alendronate 70 mg containing 5600 IU vit-D₃ (ALN/D5600) to alendronate 70 mg without additional vit-D (ALN) on the percent of patients with vit-D insufficiency [25(OH)D <15 ng/mL, primary endpoint] and serum parathyroid hormone (PTH, secondary endpoint) levels in postmenopausal, osteoporotic Korean women. Neuromuscular function was also measured. A total of 268 subjects were randomized. Overall, 35% of patients had vit-D insufficiency at baseline. After 16-weeks, there were fewer patients with vit-D insufficiency in the ALN/D5600 group (1.47%) than in the ALN group (41.67%) (p<0.001). Patients receiving ALN/D5600 compared with ALN were at a significantly decreased risk of vit-D insufficiency [odds ratio=0.02, 95% confidence interval (CI) 0.00-0.08]. In the ALN/D5600 group, significant increases in serum 25(OH)D were observed at weeks 8 (9.60 ng/mL) and 16 (11.41 ng/mL), where as a significant decrease was recorded in the ALN group at week 16 (-1.61 ng/mL). By multiple regression analysis, major determinants of increases in serum 25(OH)D were ALN/D5600 administration, seasonal variation, and baseline 25(OH)D. The least squares mean percent change from baseline in serum PTH in the ALN/D5600 group (8.17%) was lower than that in the ALN group (29.98%) (p=0.0091). There was no significant difference between treatment groups in neuromuscular function. Overall safety was similar between groups. In conclusion, the administration of 5600 IU vit-D in the ALN/D5600 group improved vit-D status and reduced the magnitude of PTH increase without significant side-effects after 16 weeks in Korean osteoporotic patients.

Antidepressants differentially related to 1,25-(OH)₂ vitamin D₃ and 25-(OH) vitamin D₃ in late-life depression

A low plasma 25-OH vitamin D3 level is a universal risk factor for a wide range of diseases and has also been implicated in late-life depression. It is currently unknown whether the biologically active form of vitamin D, that is, 1,25-(OH)2 vitamin D3, is also decreased in late-life depression, or whether vitamin D levels correlate with specific depression characteristics. We determined plasma 25-OH vitamin D3, 1,25-(OH)2 vitamin D3 and parathormone levels in 355 depressed older persons and 124 non-depressed comparison subjects (age 60 years). Psychopathology was established with the Composite International Diagnostic Interview 2.1, together with potential confounders and depression characteristics (severity, symptom profile, age of onset, recurrence, chronicity and antidepressant drug use). Adjusted for confounders, depressed patients had significantly lower levels of 25-OH vitamin D33 (Cohen's d =0.28 (95% confidence interval: 0.07-0.49), P=0.033) as well as 1,25-(OH)2 vitamin D3 (Cohen's d =0.48 (95% confidence interval: 0.27-0.70), P<0.001) than comparison subjects. Of all depression characteristics tested, only the use of tricyclic antidepressants (TCAs) was significantly correlated with lower 1,25-(OH)2 vitamin D3 levels (Cohen's d =0.86 (95% confidence interval: 0.53-1.19), P<0.001), but not its often measured precursor 25-OH vitamin D3. As vitamin D levels were significantly lower after adjustment for confounders, vitamin D might have an aetiological role in late-life depression. Differences between depressed and non-depressed subjects were largest for the biologically active form of vitamin D. The differential impact of TCAs on 25-OH vitamin D3 and 1,25-(OH)2 vitamin D3 levels suggests modulation of 1-α-hydroxylase and/or 24-hydroxylase, which may in turn have clinical implications for biological ageing mechanisms in late-life depression.

Review: Vitamin D3 deficiency results in dysfunctions of immunity with severe fatigue and depression in a variety of diseases

Recent immune data on vitamin D3 deficiency help to more clearly understand chronic fatiguing illnesses, such as autoimmune disorders, cancer and chronic fatigue syndrome (CFS). The vitamin D3 pathway is activated by stress and requires sufficient stores of precursor 25-hydroxyvitamin D3 for proper cell and immune functions. In vitamin D3 deficiency, secretion of the antimicrobial peptide cathelicidin is reduced, leading to impaired auto/xenophagy. As a result, phagocytosis, cytotoxicity, antigen processing and antigen presentation become dysregulated. In addition, vitamin D3 deficiency affects T- and B-lymphocyte activation, as well as quantity, maturation and function of regulatory natural killer T-cells and their counterparts in the gut, i.e. T-cell receptor-αβ, cluster of differentiation-8αα-positive intraepithelial lymphocytes. Consequently, innate and adaptive immunity become de-regulated, with microbial effects contributing further to this. Persistent infections, chronic inflammation and fatigue follow. Vitamin D3 substitution in such conditions may help to prevent or to ameliorate such chronic conditions, even in patients with cancer.

Vitamin D deficiency, serum leptin and osteoprotegerin levels in older diabetic patients: an input to new research avenues

The aim of this study was to assess the effects of single oral bolus of 300,000 IU Vitamin D3 on serum levels and on bone and metabolic parameters in diabetic patients. This study is a Phase IV, randomized, double-blind, placebo-controlled, monocenter clinical trial. Thirty patients, 60 years or older, with type 2 diabetes mellitus, and diabetic foot complications, were enrolled and monitored for 24 weeks: 14 were treated with Vitamin D3 and 16 with placebo. Parameters including glucose, adiponectin, leptin, osteoprotegerin (OPG), 25-hydroxyvitamin D [25(OH)D], beta-CrossLaps, osteocalcin, bone-specific isoenzyme of alkaline phosphatase, tumor necrosis factor-α and parathyroid hormone were measured at screening and baseline and 12 and 24 weeks after treatment. Analysis of covariance was used to compare treatment groups. Analysis of the data detected a significant increase in 25(OH)D serum levels both at 12 and 24 weeks with respect to baseline values only in the treated patients. Significant variations with respect to baseline values were noted in OPG (P = 0.0085) and in leptin (P = 0.0442) levels: these were lower in the placebo group at week 24 but higher in the treated group. Vitamin D3 supplementation significantly increased serum leptin and OPG levels. Further, large-scale clinical trials are warranted to confirm these results.

Vitamin D3 deficiency differentially affects functional and disease outcomes in the G93A mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a neuromuscular disease characterized by motor neuron death in the central nervous system. Vitamin D supplementation increases antioxidant activity, reduces inflammation and improves motor neuron survival. We have previously demonstrated that vitamin D(3) supplementation at 10× the adequate intake improves functional outcomes in a mouse model of ALS.

OBJECTIVE

To determine whether vitamin D deficiency influences functional and disease outcomes in a mouse model of ALS.

METHODS

At age 25 d, 102 G93A mice (56 M, 46 F) were divided into two vitamin D(3) groups: 1) adequate (AI; 1 IU D(3)/g feed) and 2) deficient (DEF; 0.025 IU D(3)/g feed). At age 113 d, tibialis anterior (TA), quadriceps (quads) and brain were harvested from 42 mice (22 M and 20 F), whereas the remaining 60 mice (34 M and 26 F) were followed to endpoint.

RESULTS

During disease progression, DEF mice had 25% (P=0.022) lower paw grip endurance AUC and 19% (P=0.017) lower motor performance AUC vs. AI mice. Prior to disease onset (CS 2), DEF mice had 36% (P=0.016) lower clinical score (CS) vs. AI mice. DEF mice reached CS 2 six days later vs. AI mice (P=0.004), confirmed by a logrank test which revealed that DEF mice reached CS 2 at a 43% slower rate vs. AI mice (HR= .57; 95% CI: 0.38, 1.74; P=0.002). Body weight-adjusted TA (AI: r=0.662, P=0.001; DEF: r=0.622, P=0.006) and quads (AI: r=0.661, P=0.001; DEF: r=0.768; P<0.001) weights were strongly correlated with age at CS 2.

CONCLUSION

Vitamin D(3) deficiency improves early disease severity and delays disease onset, but reduces performance in functional outcomes following disease onset, in the high-copy G93A mouse.

[Vitamin D deficiency in Germany, is it a danger for increased morbidityand mortality?]

Vitamin D regulates the calcium-phosphate metabolism and thereby plays an important role for the integrity and functioning of bone, muscle and nerves. Studies have shown furthermore an influence on certain types of cancer, diabetes and cardiovascular diseases. Vitamin D is mainly produced by the skin. During exposure to sunlightthe precursor7-dehydrocholesterol is transformed to colecalciferol (vitamin D3). Smaller amounts are supplied by nutrition. In our latitude vitamin D synthesis takes only place during summertime. The vitamin stored in fat tissue in generally is not sufficient for the whole winter period and accordingly insufficiency is very frequent. In a cross-sectional study all over Germany (DeViD, 2007) only about 8% of the population was vitamin D sufficient in spring time.Two prospective studies (2008) proved a correlation between vitamin D supply and overall mortality. An amelioration of vitamin D supply can be achieved either by increasing sun exposure or daily oral intake of 800-2000 IU (=20-50 microg) colecalciferol.

Vitamin D deficiency and prevention: Turkish experience

A nationwide 'vitamin D prophylaxis augmentation programme' initiated in 2005 in Turkey reduced the prevalence of rickets from 6% in 1998 to 0.1% in 2008 in children under 3 years of age. The programme included free distribution of vitamin D drops to all newborns and infants (0-12 months) visiting primary health stations throughout the country. Free disposal of vitamin D to infants is an effective strategy for preventing vitamin D-deficient rickets.

Correction of steroidopenia as a new method of hypercholesterolemia treatment

OBJECTIVE

In 2002 we proposed a new hypothesis of the etiology and pathogenesis of hypercholesterolemia. There is paucity of information in the literature regarding the association of steroidopenia and hypercholesterolemia. Our goal is to determine if the treatment of steroidopenia with hormonorestorative therapy (HT) to youthful levels will normalize total cholesterol (TC) levels.

MATERIAL AND METHODS

We retrospectively analyzed 43 hypercholesterolemic patients treated with HT. Laboratory workup included lipid profile, serum pregnenolone, dehydroepiandrosterone sulfate (DHEA-S), progesterone, total estrogen, cortisol, total testosterone, and vitamin D-3 levels at presentation with follow up ranging from 3 to 9 months. HT therapy included a combination of several agents such as pregnenolone, dehydroepiandrosterone (DHEA), triestrogen, progesterone, testosterone, hydrocortisone, and vitamin D-3.

RESULTS

HT lowered mean TC from 228.8 mg/dL to 183.7 mg/dL (19.7%) (p<0.05) in all patients. In 12 men of mean age 58, HT statistically significantly lowered TC from 227.9 mg/dL to 177.1 mg/dL (22.3%) (p<0.05). Apparently it did so mostly by lowering LDL and triglycerides (TRG) while HDL did not appreciably change. In 31women, mean age 57, TC declined from 229.2 mg/dL to 186.3 mg/dL (19%) (p<0.05). HDL, LDL, and TRG are also decreased to a statistically significant degree. These results were associated with statistically significant elevations in pregnenolone, DHEA Sulfate, testosterone, progesterone but not total estrogen, cortisol or vitamin D-3 changes in both men and women.

CONCLUSIONS

We conclude that correction of steroidopenia with the use of hormonorestorative therapy is an effective strategy for normalizing and maintaining cholesterol homeostasis.

Effects of dietary boron supplementation on some biochemical parameters, peripheral blood lymphocytes, splenic plasma cells and bone characteristics of broiler chicks given diets with adequate or inadequate cholecalciferol (vitamin D3) content

(1) The effects of 5 and 25 mg/kg boron supplementation of diets with inadequate (6.25 microg/kg) or adequate (50 microg/kg) cholecalciferol (vitamin D3) content on some biochemical parameters, tibia characteristics, peripheral blood lymphocyte and splenic plasma cell counts of broilers were investigated. (2) Supplementation of the diet with boron affected plasma concentrations of boron, iron, copper and zinc and also tibia boron, zinc and calcium concentrations but did not have any effect on tibia iron or copper concentrations or tibia ash and tibia weight values. (3) Boron supplementation caused significant increases in splenic plasma cell count but decreased the proximal and distal tibia growth plate widths. There was no effect of boron supplementation on peripheral blood alpha-naphthyl acetate esterase (ANAE) content. Whole blood haematocrit and haemoglobin counts were significantly increased by boron supplementation but there were no effects on leucocyte ratios such as eosinophil, basophil, monocyte, lymphocyte and thrombocyte. (4) In general, the findings of the present study support the hypothesis that boron has an important biological role that affects the mineral metabolism of animals by influencing both biochemical and haematological mechanisms.

[Has vitamin D(3) dosage improved in Spain? Current levels in a population sample]

INTRODUCTION

According to current classifications, the metabolite of greatest clinical interest to evaluate vitamin D(3) dosage is 25-hydroxyvitamin D(3) with a reference interval of approximately 10-70ng/ml, although many authors consider values of approximately 40ng/ml or 100nmol/l to be desirable. According to these definitions, three out of four people in Spain would have vitamin D(3) deficiency.

MATERIAL AND METHOD

The RIA-CT technique was used for diagnosis of 25(OH)D(3) to determine the population status. Subsequently, a case-control study was performed to evaluate the relationship between distinct diseases and vitamin D(3) deficiency.

RESULTS

A total of 73.2% of the cases were found to be within the range considered acceptable, according to the present classification. One hundred percent of the control group and healthy menopausal women who did not receive any kind of vitamin supplement had levels of 40 ng/ml or more.

DISCUSSION AND CONCLUSIONS

Our results indicate that the prior situation of a high prevalence of vitamin D(3) deficiency has improved and that levels are now acceptable in 26.8% of the population, with a mean value of 46.2 ng/ml, considering 10-70 ng/ml as the reference range.

[Pleiotropic action of vitamin D3 with particular stress on its role in gastrointestinal diseases in children]

This review presents aspects of pleiotropic actions of vitamin D3, in particular amongst the development period population. It describes the relationship between vitamin D3andgastrointestinal diseases (inflammatory bowel disease, celiac disease, liver and pancreas pathologies), central nervous system and cardiovascular diseases. Moreover, we underline the role of vitamin D3 in the epidemiology and pathogenesis of malignancies and autoimmune diseases.

Epidemiological investigation of femoral fractures in market pigs and the associated economic implications

The cause of an increased number of femoral fractures in market pigs from a single producer is described. Blood chemical, bone ash, radiographic, and feed analyses revealed that the fractures were caused by insufficient calcium in the diet. Associated economic and welfare implications are discussed.

[Influence of vitamin D on fertility and fetal development--review of literature]

Cholecalciferol was qualified by FDA (Food and Drug Administration) into the A category if administered in recommended doses and to the D category if the doses exceed RDA (Recommended Dietary Allowance). There are very divergent opinions among researchers concerning the optimal daily dose of vitamin D-according to some of them, the optimal dose of vitamin D should exceed 400 Ul/24h. On the other hand, there is no data to estimate the optimal dose and to formulate recommendations. It is necessary to conduct research on animal models to fully comprehend the symptoms and syndromes caused by excess or deficiency of cholecalciferol. However, the conclusions of the research done on animals should not be over-generalized. Moreover, some data concerning the influence of vitamin D administered during the pregnancy on fetal development are often ambiguous. All these facts are the reason why recommendations of vitamin D supplementation in pregnancy still remain uncertain and need thorough investigation.

Correlation between vitamin D3 deficiency and insulin resistance in pregnancy

BACKGROUND

The serum level of 25-hydroxyvitamin D deficiency has long been suspected as a risk factor for glucose intolerance and perhaps 1,25-dihydroxyvitamin D has a role in the regulation of insulin secretion. This study investigates the relation between 25-hydroxyvitamin D concentrations and insulin resistance in pregnant women.

METHODS

A cross-sectional study was conducted on 741 pregnant women referred to five educating hospital clinics. Universal screening was performed with a GCT-50 g, and those with plasma glucose levels > pr = 7.2 mmol/L were diagnosed as GDM if they had an impaired GTT-100 g based on Carpenter and Coustan criteria. The levels of insulin and C-peptide were measured during OGTT-100 g test. The homeostasis model assessment index (HOMA) equation was used as the insulin resistance index. The concentrations of 25-hydroxyvitamin D, and PTH were also measured.

RESULTS

Total prevalence of vitamin D deficiency (<25 nmol/L) was found in 70.6% of pregnant women. Prevalence of severe vitamin D deficiency (<12.5) in GDM patients was higher than in normoglycaemic pregnancies. The regression model revealed a strong correlation between the HOMA index and serum levels of vitamin D.

CONCLUSIONS

These results show that a positive correlation of 25(OH) vitamin D concentrations with insulin sensitivity and vitamin D deficiency could be a confirmative sign of insulin resistance.

The effect of cholecalciferol (vitamin D3) on the risk of fall and fracture: a meta-analysis

We evaluated the effect of supplementation with vitamin D(3) (excluding the potential effect of calcium supplementation) on the risk of fall and fracture, primarily in postmenopausal women, using a systematic literature review of MEDLINE, EMBASE, BIOSIS and the Cochrane Database of Systematic Reviews for the period January 1985 to June 2005. Studies examining the effect of vitamin D versus placebo on the risk of fall or fracture in postmenopausal females were of particular interest. Studies of vitamin D in combination with calcium were also included where the control group was treated with calcium alone. Studies of men and women where results for men and women were not presented separately were included. Nine studies met the inclusion criteria. Our primary meta-analyses examined the effect of vitamin D(3) on the risk of fall or fracture; additional analyses examined baseline and difference between baseline and final levels of several serum and urinary biochemical markers. The pooled relative risk (RR) for vitamin D(3) preventing falls was 0.88 (95%CI 0.78-1.00). For fractures, the pooled RR for vitamin D(3) preventing non-vertebral fractures was 0.96 (95%CI 0.84-1.09) and the pooled RR for vitamin D(3) preventing vertebral fractures was 1.22 (95%CI 0.64-2.31). In a subgroup analysis of post-menopausal women, the pooled RR for vitamin D(3) preventing falls was 0.92 (95%CI 0.75-1.12) and in preventing non-vertebral fractures the pooled RR was 0.81 (95%CI 0.48-1.34). There is a trend towards a reduction in the risk of fall among patients treated with vitamin D(3) alone compared with placebo, suggesting that vitamin D(3) should be an integral part of effective osteoporosis management.

Changes in calcium, 25(OH) vitamin D3 and other biochemical factors during pregnancy

INTRODUCTION AND AIMS

Calcium and vitamin D play major roles in calcium homeostasis and skeletal development, especially during pregnancy. This study was conducted to determine changes in calcium, 25 hydroxy [25(OH)] vitamin D3 and other biochemical factors (PTH, osteocalcin, alkaline phosphatase, magnesium, phosphorus) related to calcium homeostasis and bone turnover during pregnancy and compare the values to those of non-pregnant women.

MATERIALS AND METHODS

In a cohort study, 48 pregnant women, in their first trimester of pregnancy (12+/-2.7 weeks), from 5 prenatal care centers, and 47 non-pregnant women randomly selected from the Tehran Lipid and Glucose Study (TLGS) population were enrolled. These pregnant women were followed in their second (26+/-1.9 weeks) and third trimesters (37+/-3.2 weeks) of pregnancy. Samples were drawn from June 2002 to March 2003. Including criteria were healthy women with no background of disease. Women using photo protection and calcium and vitamin D supplementation were excluded. A questionnaire was used to obtain demographic information for both groups. Venous blood samples were taken after 12-14 h of overnight fasting to measure serum calcium, phosphorus, magnesium, alkaline phosphatase, PTH, 25 (OH) vitamin D3 and serum osteocalcin levels. The repeated measures analysis of variance and t-test were used for statistical analysis. Data were matched for age and weight in both the case (in the first trimester) and control groups.

RESULTS

Significant differences were found in the mean serum levels of osteocalcin and alkaline phosphatase between the three trimesters of pregnancy (p< 0.001). Osteocalcin was significantly higher in the first trimester as compared to second and third trimesters of pregnancy. Alkaline phosphatase was significantly lower in the first trimester as compared to the second and third trimesters of pregnancy and their controls. There was also a significant difference in osteocalcin in the second and third trimesters and alkaline phosphatase in the first and third trimesters of pregnancy in comparison to the control group. The mean values of osteocalcin were 12.7+/-8.5, 8.1+/-6.9, 5.6+/-5.0 and 13.9+/-7.9 ng/ml, respectively, and mean values for alkaline phosphatase were 115+/-38, 125+/-37, 174+/-61 and 134+/-35.0 Iu/l, respectively. In the first trimester, alkaline phosphatase was lower and osteocalcin was higher than in the second and third trimesters. In the first trimester of pregnancy, 20 and 40% of women had 25(OH) vitamin D3 < 10 and < 20 ng/ml, respectively, and 19% of women had serum calcium levels < 8.6 mg/dl.

CONCLUSION

60% of women in the first trimester, 48% in the second and 47% in the third trimester had either severe or moderate vitamin D deficiency. It is recommended that the importance of calcium supplements with vitamin D in pregnant women be stressed for these individuals.

Association of 1.25 vitamin D3 deficiency, disease activity and low bone mass in ankylosing spondylitis

Vertebral fractures due to osteoporosis are a common but frequently unrecognized complication in established ankylosing spondylitis (AS). It is known that inflammatory activity in rheumatic diseases (i.e., proinflammatory cytokines) itself plays a possible role in the pathophysiology of bone loss. The aim of this study was to analyze whether inflammatory activity and an alteration of the vitamin D metabolism play a substantial role in the loss of bone mass in AS. In this cross-sectional study, 58 patients with established AS and an age- and sex-matched control group were examined. The vitamin D status was investigated, as was, in parallel, the relationship to disease activity (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], Bath Ankylosing Spondylitis Disease Activity Index [BASDAI]), markers of bone metabolism (parathyroid hormone [PTH], 1.25 vitamin D3, 25 vitamin D3), calcium, bone alkaline phosphatase (bone-AP), urine cross-links, and plasma tumor necrosis factor alpha (TNFalpha). Bone mineral density was measured by quantitative computed tomography (QCT) of the lumbar spine. Osteoporosis was diagnosed in early as well as in progressive stages of AS (23/58=39.6%). Furthermore, serum levels of 1.25 vitamin D3 and PTH were negatively correlated with disease activity and TNFalpha. The excretion of cross-links showed a positive correlation with disease activity and TNFalpha, and 1.25 vitamin D3 and PTH were positively correlated with bone-AP. TNFalpha also positively correlated with disease activity. AS patients with osteoporosis showed significantly increased CRP, ESR, cross-links and PTH and a significantly decreased 1.25 D3. Osteoporosis is frequent in AS and high disease activity is associated with an alteration in vitamin D metabolites and increased levels of bone resorption in active AS. Our findings propose a close association of BMD, bone metabolism and inflammatory activity, possibly related to vitamin D inflammation interactions.

Incidence of hypertrophic scars among African Americans linked to vitamin D-3 metabolism?

The pathogenesis and progression of wound-healing involve intricate pathways and numerous chemical mediators. This remains an area of intense study as undesirable results of this process, such as hypertrophic scars and keloids, can result in significant morbidity. These lesions are distinct in their characteristics, although they are similar in their distribution in patients with darker skin colors. There is a robust inflammatory mechanism behind the formation of hypertrophic scars and keloids. Furthermore, their development may be intimately related to vitamin D-3, which has been shown to be a powerful anti-inflammatory agent. This chemical is made in the skin, whose production is influenced by various factors of which the amount of melanin is a crucial one. More specifically, an increase in pigmentation has been shown to decrease the amount of vitamin D-3 synthesis in the skin. Thus, this paper proposes the hypothesis linking the propensity of inflammation and subsequent scarring in darker-skinned individuals to the reduced levels of vitamin D-3 production in their skin.

Developmental Vitamin D3 deficiency alters the adult rat brain

There is growing evidence that Vitamin D(3) (1,25-dihydroxyvitamin D(3)) is involved in brain development. We have recently shown that the brains of newborn rats from Vitamin D(3) deficient dams were larger than controls, had increased cell proliferation, larger lateral ventricles, and reduced cortical thickness. Brains from these animals also had reduced expression of nerve growth factor (NGF) and glial cell line-derived neurotrophic factor. The aim of the current study was to examine if there were any permanent outcomes into adulthood when the offspring of Vitamin D(3) deficient dams were restored to a normal diet. The brains of adult rats were examined at 10 weeks of age after Vitamin D(3) deficiency until birth or weaning. Compared to controls animals that were exposed to transient early Vitamin D(3) deficiency had larger lateral ventricles, reduced NGF protein content, and reduced expression of a number genes involved in neuronal structure, i.e. neurofilament or MAP-2 or neurotransmission, i.e. GABA-A(alpha4). We conclude that transient early life hypovitaminosis D(3) not only disrupts brain development but leads to persistent changes in the adult brain. In light of the high incidence of hypovitaminosis D(3) in women of child-bearing age, the public health implications of these findings warrant attention.

Maternal vitamin D3 deprivation and the regulation of apoptosis and cell cycle during rat brain development

Recently, it has been shown that the prenatal vitamin D(3) depletion is associated with altered brain development. Given the antiproliferative and pro-apoptotic properties of vitamin D(3) in various cell types, we examined the effects of maternal vitamin D(3) deprivation on cell proliferation and apoptosis within the rat cortex at several developmental stages. Our results confirm that vitamin D(3) regulates these processes in the developing brain at both cellular and molecular levels. Compared to control animals, the embryos and pups from vitamin D(3) depleted mothers had significantly less apoptotic cells, this finding being most pronounced at birth. Additionally, there were significantly more mitotic cells but this was not associated with any particular developmental period. Targeted gene arrays specific for apoptosis and cell cycle genes confirmed a pattern of transcription deregulation in the deplete group consistent with the known properties of vitamin D(3). While most current vitamin D(3) research is focussed on the pro-apoptotic and prodifferentiating properties of vitamin D(3) as adjuncts for the treatment of cancers, our findings highlight the important role that this hormone plays in normal development via these same properties specifically in the brain.

[Osteoporosis and cardiovascular disease--two sides of the same coin?]

BACKGROUND

Osteoporosis and cardiovascular disease have numerous epidemiologic changes, health economic consequences, and molecular mechanisms in common, which are highlighted in this short review.

EPIDEMIOLOGY AND CLINICAL STUDIES

The incidence of osteoporosis and cardiovascular disease is increasing in western societies, and genetic background, nutrition and psychologic factors play important roles in the pathogenesis of both diseases. The presence of a decreased bone mass or osteoporotic vertebral fractures are associated with an increased cardiovascular mortality. Calcaneal bone loss of 1 SD (standard deviation) as measured by osteodensitometry is associated with a 1.31 times increased risk for the occurrence of stroke.

MOLECULAR MECHANISMS

The observed increase in interleukin-6 and tumor necrosis factor serum concentrations during the menopause contributes to osteoporotic bone loss and is associated with arteriosclerosis. Furthermore, the presence of hydroxyapatite in arteriosclerotic plaques supports the notion of common pathogenetic mechanisms for both, osteoporosis and arteriosclerosis. Osteopontin, bone GLA protein and bone morphogenetic protein-2, which have first been isolated from the organic bone matrix, are also present in arteriosclerotic plaques. 1,25-dihydroxycholecalciferol potently stimulates bone matrix mineralization and is also a negative regulator of the renin-angiotensin system; therefore vitamin D(3) deficiency in addition to bone metabolism also affects blood pressure. Osteoporosis and arteriosclerosis develop in mice lacking the osteoprotegerin gene and also in klotho gene knockout mice.

CONCLUSION

Diagnosis of osteopenia, osteoporosis and osteoporotic vertebral or hip fractures indicates the presence of an increased cardiovascular risk which needs to be addressed by the physician who cares for patients with osteoporosis. The experimental finding of an osteoanabolic effect of statins supports the possibility of common pathogenetic disturbances which may be responsible for the simultaneous and frequent manifestation of osteoporosis and arteriosclerosis in elderly patients.

Vitamin D3 and brain development

Evidence for the presence of the vitamin D receptor in brain implies this vitamin may have some function in this organ. This study investigates whether vitamin D(3) acts during brain development. We demonstrate that rats born to vitamin D(3)-deficient mothers had profound alterations in the brain at birth. The cortex was longer but not wider, the lateral ventricles were enlarged, the cortex was proportionally thinner and there was more cell proliferation throughout the brain. There were reductions in brain content of nerve growth factor and glial cell line-derived neurotrophic factor and reduced expression of p75(NTR), the low-affinity neurotrophin receptor. Our findings would suggest that low maternal vitamin D(3) has important ramifications for the developing brain.

[Spontaneous bilateral fractures of the femoral neck. Etiology-frequency-diagnosis-therapy]

INTRODUCTION

Medial and pertrochanteric fractures of the femoral neck occur commonly in patients with bone weakness due to osteoporosis or osteomalacia. Combined bilateral hip injury is much rarer.

PATIENTS AND METHODS

The case of a Turkish woman with bilateral fractures of the femoral neck due to secondary hyperparathyroidism caused by nutritional vitamin-D 3 deficiency is described and compared to 80 cases of bilateral hip fractures mentioned in English and German literature.

RESULTS

Until the late 1950's the most common reason for simultaneous bilateral femoral neck fractures was convulsive therapy of psychosis by drug or electroshock without use of relaxants, followed by seizures of other origin. Primary and secondary bone diseases are the most common reason for two-fold spontaneous bilateral fractures of the femoral neck.

CONCLUSION

At the time of first pain radiological findings are often normal. In this situation MRI, isotope bone scanning or additional chemical diagnostics have proved to be useful. The medical regulation of the bone disease is of highest priority. On account of the pain, bone stability and deformation, conservative and operative therapy such as osteosynthesis or THR has to be performed.

Vitamin D-deficient rickets: a multifactorial disease

We present a case of an African-American child with vitamin D-deficient rickets. In addition to being solely breast-fed for the period of 1 year, he resided in New England, where exposure to ultraviolet light is limited owing to its northern latitude and long cold winters. He presented with classical signs of nutritional rickets and was immediately responsive to treatment with vitamin D supplementation.

PTH regulates expression of ClC-5 chloride channel in the kidney

Mutations in the chloride channel, ClC-5, have been described in several inherited diseases that result in the formation of kidney stones. To determine whether ClC-5 is also involved in calcium homeostasis, we investigated whether ClC-5 mRNA and protein expression are modulated in rats deficient in 1alpha,25(OH)(2) vitamin D(3) with and without thyroparathyroidectomy. Parathyroid hormone (PTH) was replaced in some animals. Vitamin D-deficient, thyroparathyrodectomized rats had lower serum and higher urinary calcium concentrations compared with control animals as well as lower serum PTH and calcitonin concentrations. ClC-5 mRNA and protein levels in the cortex decrease in vitamin D-deficient, thyroparathyroidectomized rats compared with both control and vitamin D-deficient animals. ClC-5 mRNA and protein expression increase near to control levels in vitamin D-deficient, thyroparathyroidectomized rats injected with PTH. No significant changes in ClC-5 mRNA and protein expression in the medulla were detected in any experimental group. Our results suggest that PTH modulates the expression of ClC-5 in the kidney cortex and that neither 1alpha,25(OH)(2) vitamin D(3) nor PTH regulates ClC-5 expression in the medulla. The pattern of expression of ClC-5 varies with urinary calcium. Animals with higher urinary calcium concentrations have lower levels of ClC-5 mRNA and protein expression, suggesting that the ClC-5 chloride channel plays a role in calcium reabsorption.

Preliminary investigation of the vitamin D status of pet rabbits

The plasma concentrations of 1,25-dihydroxycholecalciferol (1,25-(OH)2D3) (vitamin D3) were measured in blood samples taken from one wild rabbit and 13 pet rabbits at different times of the year. Some pet rabbits had low or undetectable plasma concentrations of 1,25-(OH)2D3 especially if they were kept in hutches. Rabbits with more access to sunlight had higher concentrations of 1,25-(OH)2D3.

A hypothesis concerning deficiency of sunlight, cold temperature, and influenza epidemics associated with the onset of acute lymphoblastic leukemia in northern Finland

Research to detect new factors contributing to the etiology of acute leukemia (AL) is urgently needed. Located between latitudes 65 degrees and 70 degrees north, the population in northern Finland is exposed to extreme seasonal alterations of ultraviolet-B light and temperature. There is also a seasonal variation of both the 25(OH)- and 1,25(OH)2-D3 vitamin serum concentrations. In the present work, the frequencies of different types and age-groups at diagnosis of AL were compared during the dark and light months of the year, to uncover seasonality. Between January 1972 and December 1986, 300 consecutive patients aged >/=16 years and diagnosed as having AL were enrolled. The observed mean monthly global solar radiation, temperature measurements, and influenza epidemics were compared with the monthly occurrence of AL. Both acute lymphoblastic leukemia (ALL) (p=0.006) and total AL (p=0.015) were diagnosed excessively in the dark and cold compared with light and warm period of the year. There was a tendency for de novo leukemia to increase also in the dark and cold, but for acute myeloid leukemia (AML) patients the excess was not significant. Age >/=65 was strongly associated with the dark and cold season (p=0.003). Significantly more ALL (p=0.005) and de novo leukemias (p=0.029) were observed during influenza epidemics than during nonepidemic periods. However, a seasonality, i. e., the fluctuation of numbers of AL cases, was not determined, either monthly or during different photo- and temperature periods or influenza epidemics; this might be due to the small numbers of patients studied. Nevertheless, it is hypothesized that sunlight deprivation in the arctic winter can lead to a deficiency of the 1, 25(OH)2D3 vitamin, which might stimulate leukemic cell proliferation and block cell differentiation through dysregulation of growth factors in the bone marrow stromal cells, causing one mutation and an overt ALL in progenitor cells damaged during the current or the previous winter by influenza virus, the other mutation.

The de novo synthesis of numerous proteins is decreased during vitamin D3 deficiency and is gradually restored by 1, 25-dihydroxyvitamin D3 repletion in the islets of langerhans of rats

Since both the release and de novo biosynthesis of insulin are severely decreased by vitamin D3 deficiency and improved by 1, 25-dihydroxyvitamin D3 (1,25(OH)2D3) repletion following a 6-h delay in the rat, the present experiments investigated the effects of vitamin D3 deficiency on the biosynthesis of heavier molecular weight proteins using electrophoretic separation. Gel protein staining by Coomassie blue showed very different profiles for islets protein production from 4-week vitamin D3-deficient rats compared with normal islets. The pattern was characterised by a decrease in high molecular weight proteins, concomitantly accompanied by an increase in low molecular weight proteins. This tendency was partially reversed in vivo by 1,25(OH)2D3 repletion treatment for 7 days and was evident after only 16 h of treatment. In parallel with these in vivo observations, which represent a static index of islets protein production, a kinetic study was performed in vitro by a double-labelling method allowing us to measure the de novo synthesis of proteins in islets during a strong 16.7 mM glucose stimulation. Comparison of 3H and 14C labelled samples was achieved via coelectrophoresis to avoid experimental artefacts. The study of the ratio of d.p.m. 3H/d.p.m. 14C for each molecular weight protein in islets stimulated by 16.7 mM glucose (versus basal 4.2 mM glucose) showed an increase in the height of certain peaks: 150, 130 and 8.5 kDa. Under the same conditions, islets from 4-week vitamin D3-deficient rats (versus normal islets) presented a large deficit of numerous newly synthesised proteins and particularly those implicated in the response to glucose stimulation. In vitro repletion of 1,25(OH)2D3 tended to reverse, at least in part, the deleterious effect of vitamin D3 deficiency on the de novo protein synthesis of islets but these effects were gradual. Indeed, there was no detectable effect at 2 h incubation, but 1,25(OH)2D3 increased the 60 to 65 kDa, 55 kDa, and 9 to 8 kDa molecular mass proteins at 4 h, and increased the level of most newly synthesised proteins at 6 h. These data support the hypothesis of a beneficial genomic influence of 1,25(OH)2D3 that occurs progressively within the islets of Langerhans and which may prepare the beta cells for an enhanced response to glucose stimulation.

Vitamin D3 deficiency and alterations of glucose metabolism in rat endocrine pancreas

After 5 weeks of vitamin D3 deficiency, rats exhibited signs of rachitism, hypocalcaemia and hypoinsulinaemia. As the glucose-induced insulin release process requires calcium and energy production from glucose metabolism within beta cells of Langerhans islets, several steps in the glycolytic pathway and the tricarboxylic acid cycle within beta cells were investigated in vitro. The sensitivity of islets to glucose was studied during incubations in the presence of crescent concentrations of glucose (4.2 to 16.7 mM). Comparison of 50% maximal insulin response showed no modifications induced by vitamin D3 deficiency despite a large fall in the secretory capacity of beta cells. The use of two secretagogues (D-glucose and D-glyceraldehyde) to stimulate insulin release at two different glycolysis steps gave similar responses during perifusions performed in the presence of crescent concentrations of these nutrients, indicating that vitamin D3 deficiency was not a major influence on the first steps in glycolysis. Glucose utilisation by islets, as determined by 3HOH production from D-[5-3H]glucose, was slightly decreased during glucose stimulation of islets from vitamin D3-deficient rats, whereas glucose oxidation inside the tricarboxylic acid cycle, as measured by 14CO2 production from D-[6-14C]glucose, was severely affected. These data, which suggest that vitamin D3 deficiency affects the glycolytic pathway after the D-glyceraldehyde step and mainly alters oxidative events within the tricarboxylic acid cycle, support the hypothesis of an alteration of mitochondrial metabolism.

Hypocalcemic induced increase in creatine kinase in rats

Calcium plays an important role in various myopathies. We report on an animal model with increased plasma creatine kinase (CK) resulting from hypocalcemia that will provide clues for studying human hypocalcemic myopathy. Male Wistar rats were pair-fed either a control or a calcium- and vitamin D3-deficient diet for 1, 2, 3, 4, or 5-6 weeks after weaning (3 weeks old). In the deficient diet-fed rats, plasma creatine kinase was increased and was accompanied by marked hypocalcemia. The omission of calcium and vitamin D3 from the diet for 1 or 2 weeks was enough to cause increased plasma creatine kinase; the creatine kinase ratio of deficient diet-fed rats to controls was 4.84 (1,777 IU L(-1)/367 IU L(-1)), and the calcium ion ratio was 0.41 (1.8 mg dL(-1)/4.4 mg dL(-1)) after 2 weeks. These values returned to control levels on treatment of the rats with the control diet and 1alpha-OH-vitamin D3 for 1 week.

Moderate excess of dietary vitamin E does not exacerbate cholecalciferol deficiency in young broiler chicks

1. The combined effect of moderate excess dietary vitamin E and marginal amounts of dietary cholecalciferol on the performance and tibia bone ash of young male broiler chicks was evaluated. Vitamin E (alpha-tocopheryl acetate) and cholecalciferol were added to a commercial diet not already supplemented with these vitamins, at concentrations of 0 and 150 mg/kg, and 1.875, 5 and 25 micrograms/kg, respectively, and fed to chicks for 23 d. 2. Vitamin E concentration and its combinations with cholecalciferol did not significantly (P > 0.05) affect food intake, weight gain, food efficiency and bone ash. These variables were significantly (P < 0.001) lower in chicks fed on the diets supplemented with 1.875 micrograms cholecalciferol/kg compared with the values observed with the 2 other concentrations of this vitamin. There were no differences in the effects of 5 and 25 micrograms cholecalciferol/kg diet on the above variables. 3. It was concluded that vitamin E, at a concentration of 150 mg/kg diet, did not aggravate a mild cholecalciferol deficiency.

Low extracellular calcium enhances beta cell sensitivity to the stimulatory influence of 1,25-dihydroxyvitamin D3 on insulin release by islets from vitamin D3-deficient rats

The beneficial effect of 1,25-dihydroxyvitamin D3 [1,25 (OH)2 D3] on insulin secretion from beta cells in hypocalcemic vitamin D3-deficient rats is now well established. Moreover, few data concerning the mechanism of 1,25 (OH) 2D3 efficiency as a function of the severity of hypocalcemia. In the present experiment, we submitted islets from vitamin D3-deficient rats to in vitro exposure to a range of decreasing extracellular Ca2+ concentrations ([Ca2+]ex), from 0.5 mM to 0.6 mM, during a 6-h 10-8 M 1,25 (OH) 2D3 induction. Thereafter, we compared the effect of this pretreatment on the islets' insulin response to a given stimulus. Various stimuli were used, and we measured in parallel the variations of 86Rb+ and 45Ca2+ efflux and insulin release into the perifusion medium. In the presence of 1,25 (OH) 2D3, we observed an inverse correlation between the [Ca2+]ex pre-exposure and the amplitude of the insulin response to certain stimuli studied, suggesting that beta cells that were pre-exposed to low [Ca2+]ex became more sensitive to the beneficial effect of 1,25 (OH) 2D3 on insulin release. This effect was observed when beta cells were activated by acetylcholine but only during its second phase of stimulation, and more particularly with the barium plus theophylline stimulus. In contrast, insulin release was not affected by [Ca2+]ex pre-exposure during 1,25 (OH) 2D3 induction in response to acetylcholine during its first phase of stimulation, thus excluding any mechanism mediated via nutrient pathways, membrane depolarization, or inositol triphosphate (IP3)-dependent events. Moreover, the islets that were pre-exposed to a 10-fold [Ca2+]ex exhibited only a 50% lower 45Ca2+ content after 45Ca2+ loading, suggesting a different or relatively more efficient storage capacity in the presence of low extracellular calcium. Studies of 45Ca2+ efflux showed that the mobilization of Ca2+ stores induced by a barium plus theophylline stimulus, in the absence of calcium in the perifusion medium, was more efficient in islets pre-exposed to low [Ca2+]ex, whereas the acetylcholine-IP 3-induced mobilization of Ca2+ from reticular stores was not affected. These results generated the hypothesis that 1,25 (OH)2D3 may prepare the beta cells during their pre-exposure to low [Ca2+]ex to become more efficient as concerns insulin release via a more efficient mobilization of 45Ca2+ stores (mitochondrial?) and by an activation of release potentiating systems via protein kinase C protein kinase A pathways.