BACKGROUND

Low vitamin D status may increase mortality risk.

OBJECTIVE

We used nonparametric ("highest compared with lowest" categories) and parametric (>2 categories) statistical models to evaluate associations of 25-hydroxyvitamin D [25(OH)D] serum concentrations and mortality in observational studies among general populations.

METHODS

We searched PubMed, EMBASE, Web of Science, and reference lists for relevant articles. We included studies that contained data on relative risks (RRs) for mortality for different 25(OH)D concentrations, which included a corresponding measure of uncertainty, and this yielded 14 prospective cohort studies that involved 5562 deaths out of 62,548 individuals. We applied log-transformed RRs and CIs, adjusted for the maximal number of confounding variables. In the parametric model, which is based on 11 studies and 59,231 individuals, we used the lowest quantile as the reference category.

RESULTS

For "highest compared with lowest" categories of 25(OH)D, the estimated summary RR of mortality was 0.71 (95% CI: 0.50, 0.91). In the parametric model, the estimated summary RRs (95% CI) of mortality were 0.86 (0.82, 0.91), 0.77 (0.70, 0.84), and 0.69 (0.60, 0.78) for individuals with an increase of 12.5, 25, and 50 nmol 25(OH)D serum values/L, respectively, from a median reference category of ∼27.5 nmol/L. There was, however, no significant decrease in mortality when an increase of ∼87.5 nmol/L above the reference category occurred.

CONCLUSIONS

Data suggest a nonlinear decrease in mortality risk as circulating 25(OH)D increases, with optimal concentrations ∼75-87.5 nmol/L.

OBJECTIVE

To compare the measurement properties over time of five generic health status assessment techniques.

METHODS

Five health status measures were completed on two occasions by a sample of workers with musculoskeletal disorders. They included the SF-36, Nottingham Health Profile, Health Status Section of the Ontario Health Survey (OHS), Duke Health Profile, the Sickness Impact Profile and a self-report of change in health between tests.

METHODS

Subjects were accrued from a work site (within one week of injury) (n = 53), physiotherapy clinics (four weeks after injury), (n = 34), and a tertiary level rehabilitation center (more than four weeks after injury) (n = 40).

METHODS

Intraclass correlation coefficients (ICC) derived from nonparametric one-way analysis of variance were used for test-retest reliability in those who had not changed (n = 49). Various responsiveness statistics were used to evaluate responsiveness in those who claimed they had a positive change in health (n = 45) and in those who would have been expected to have a positive change (n = 79).

RESULTS

Of the 127 subjects recruited, 114 completed both questionnaires (89.8%). In the subjects who reported no change in health, analysis of targeted dimensions (overall scores, physical function, and pain) demonstrated acceptable to excellent test-retest reliability in all but the Duke Health Profile. In subjects with change in health, the SF-36 was the most responsive measure (moderate to large effect sizes [0.55-0.97] and standardized response means ranging between 0.81 and 1.13).

CONCLUSIONS

The results suggest that the SF-36 was the most appropriate questionnaire to measure health changes in the population studied. The selection of a health status measure must be context-specific, taking into account the purpose and population of the planned research.

OBJECTIVE

Evidence on the association of vitamin D with cardiovascular risk factors in youth is very limited. We examined whether low serum vitamin D levels (25-hydroxyvitamin D [25(OH)D]) are associated with cardiovascular risk factors in US adolescents aged 12 to 19 years.

METHODS

We conducted a cross-sectional analysis of 3577 fasting, nonpregnant adolescents without diagnosed diabetes who participated in the 2001-2004 National Health and Nutrition Examination Survey. Cardiovascular risk factors were measured using standard methods and defined according to age-modified Adult Treatment Panel III definitions.

RESULTS

Mean 25(OH)D was 24.8 ng/mL; it was lowest in black (15.5 ng/mL), intermediate in Mexican American (21.5 ng/mL), and highest in white (28.0 ng/mL) adolescents (P < .001 for each pairwise comparison). Low 25(OH)D levels were strongly associated with overweight status and abdominal obesity (P for trend < .001 for both). After adjustment for age, gender, race/ethnicity, BMI, socioeconomic status, and physical activity, 25(OH)D levels were inversely associated with systolic blood pressure (P = .02) and plasma glucose concentrations (P = .01). The adjusted odds ratio (95% confidence interval) for those in the lowest (<15 ng/mL) compared with the highest quartile (>26 ng/mL) of 25(OH)D for hypertension was 2.36 (1.33-4.19); for fasting hyperglycemia it was 2.54 (1.01-6.40); for low high-density lipoprotein cholesterol it was 1.54 (0.99-2.39); for hypertriglyceridemia it was 1.00 (0.49-2.04); and for metabolic syndrome it was 3.88 (1.57-9.58).

CONCLUSIONS

Low serum vitamin D in US adolescents is strongly associated with hypertension, hyperglycemia, and metabolic syndrome, independent of adiposity.

The functions of dendritic cells (DCs) are tightly regulated such that protective immune responses are elicited and unwanted immune responses are prevented. 1 alpha 25-dihydroxyvitamin D(3) (1 alpha 25(OH)(2)D(3)) has been identified as a major factor that inhibits the differentiation and maturation of DCs, an effect dependent upon its binding to the nuclear vitamin D receptor (VDR). Physiological control of 1 alpha 25(OH)(2)D(3) levels is critically dependent upon 25-hydroxyvitamin D(3)-1 alpha-hydroxylase (1 alpha OHase), a mitochondrial cytochrome P450 enzyme that catalyzes the conversion of inactive precursor 25-hydroxyvitamin D(3) (25(OH)D(3)) to the active metabolite 1 alpha 25(OH)(2)D(3). Using a human monocyte-derived DC (moDC) model, we have examined the relationship between DC VDR expression and the impact of exposure to its ligand, 1 alpha 25(OH)(2)D(3). We show for the first time that moDCs are able to synthesize 1 alpha 25(OH)(2)D(3) in vitro as a consequence of increased 1 alpha OHase expression. Following terminal differentiation induced by a diverse set of maturation stimuli, there is marked transcriptional up-regulation of 1 alpha OHase leading to increased 1 alpha OHase enzyme activity. Consistent with this finding is the observation that the development and function of moDCs is inhibited at physiological concentrations of the inactive metabolite 25(OH)D(3). In contrast to 1 alpha OHase, VDR expression is down-regulated as monocytes differentiate into immature DCs. Addition of 1 alpha 25(OH)(2)D(3) to moDC cultures at different time points indicates that its inhibitory effects are greater in monocyte precursors than in immature DCs. In conclusion, differential regulation of endogenous 1 alpha 25(OH)(2)D(3) ligand and its nuclear receptor appear to be important regulators of DC biology and represent potential targets for the manipulation of DC function.

To identify the intracellular signals which increase the adhesiveness of leukocyte function-associated antigen 1 (LFA-1), we established an assay system for activation-dependent adhesion through LFA-1/intercellular adhesion molecule 1 ICAM-1 using mouse lymphoid cells reconstituted with human LFA-1 and then introduced constitutively active forms of signaling molecules. We found that the phorbol myristate acetate (PMA)-responsive protein kinase C (PKC) isotypes (alpha, betaI, betaII, and delta) or phosphatidylinositol-3-OH kinase (PI 3-kinase) itself activated LFA-1 to bind ICAM-1. H-Ras and Rac activated LFA-1 in a PI 3-kinase-dependent manner, whereas Rho and R-Ras had little effect. Unexpectedly, Rap1 was demonstrated to function as the most potent activator of LFA-1. Distinct from H-Ras and Rac, Rap1 increased the adhesiveness independently of PI 3-kinase, indicating that Rap1 is a novel activation signal for the integrins. Rap1 induced changes in the conformation and affinity of LFA-1 and, interestingly, caused marked LFA-1/ICAM-1-mediated cell aggregation. Furthermore, a dominant negative form of Rap1 (Rap1N17) inhibited T-cell receptor-mediated LFA-1 activation in Jurkat T cells and LFA-1/ICAM-1-dependent cell aggregation upon differentiation of HL-60 cells into macrophages, suggesting that Rap1 is critically involved in physiological processes. These unique functions of Rap1 in controlling cellular adhesion through LFA-1 suggest a pivotal role as an immunological regulator.

The National Institute on Aging's Interventions Testing Program was established to evaluate agents that are purported to increase lifespan and delay the appearance of age-related disease in genetically heterogeneous mice. Up to five compounds are added to the study each year and each compound is tested at three test sites (The Jackson Laboratory, University of Michigan, and University of Texas Health Science Center at San Antonio). Mice in the first cohort were exposed to one of four agents: aspirin, nitroflurbiprofen, 4-OH-alpha-phenyl-N-tert-butyl nitrone, or nordihydroguaiaretic acid (NDGA). Sample size was sufficient to detect a 10% difference in lifespan in either sex,with 80% power, using data from two of the three sites. Pooling data from all three sites, a log-rank test showed that both NDGA (p=0.0006) and aspirin (p=0.01) led to increased lifespan of male mice. Comparison of the proportion of live mice at the age of 90% mortality was used as a surrogate for measurement of maximum lifespan;neither NDGA (p=0.12) nor aspirin (p=0.16) had a significant effect in this test. Measures of blood levels of NDGA or aspirin and its salicylic acid metabolite suggest that the observed lack of effects of NDGA or aspirin on life span in females could be related to gender differences in drug disposition or metabolism. Further studies are warranted to find whether NDGA or aspirin, over a range of doses,might prove to postpone death and various age-related outcomes reproducibly in mice.

We have investigated the relationship between seed dormancy and abscisic acid (ABA) metabolism in the monocot barley and the dicot Arabidopsis. Whether dormant (D) or non-dormant (ND), dry seed of Arabidopsis and embryos of dry barley grains all had similarly high levels of ABA. ABA levels decreased rapidly upon imbibition, although they fell further in ND than in D. Gene expression profiles were determined in Arabidopsis for key ABA biosynthetic [the 9-cis epoxycarotenoid dioxygenasegene family] and ABA catabolic [the ABA 8'-hydroxylase gene family (CYP707A)] genes. Of these, only the AtCYP707A2 gene was differentially expressed between D and ND seeds, being expressed to a much higher level in ND seeds. Similarly, a barley CYP707 homologue, (HvABA8'OH-1) was expressed to a much higher level in embryos from ND grains than from D grains. Consistent with this, in situ hybridization studies showed HvABA8'OH-1 mRNA expression was stronger in embryos from ND grains. Surprisingly, the signal was confined in the coleorhiza, suggesting that this tissue plays a key role in dormancy release. Constitutive expression of a CYP707A gene in transgenic Arabidopsis resulted in decreased ABA content in mature dry seeds and a much shorter after-ripening period to overcome dormancy. Conversely, mutating the CYP707A2 gene resulted in seeds that required longer after-ripening to break dormancy. Our results point to a pivotal role for the ABA 8'-hydroxylase gene in controlling dormancy and that the action of this enzyme may be confined to a particular organ as in the coleorhiza of cereals.

We performed a meta-analysis of cross-sectional studies on serum 25(OH)D status globally. Serum 25(OH)D levels on average were 54 nmol/l, were higher in women than men, and higher in Caucasians than in non-Caucasians. There was no trend in serum 25(OH)D level with latitude. Vitamin D deficiency was widespread.

BACKGROUND

We studied vitamin D status (expressed as serum 25-hydroxy-vitamin D [25(OH)D]) in native subjects worldwide.

METHODS

Meta-analysis and meta-regression of studies reporting on 25(OH)D in healthy subjects retrieved from Pubmed, Embase and Web of Science using the terms "serum", "25-hydroxy-vitamin D", "cholecalciferol", and "human". A total of 394 studies were included.

RESULTS

The mean 25(OH)D level was 54 nmol/l (95% CI: 52-57 nmol/l). Women had borderline significantly higher 25(OH)D levels than men, and Caucasians had higher levels than non-Caucasians. 25(OH)D levels were higher in subjects aged >15 years than in younger subjects. Unadjusted there was no significant decrease in 25(OH)D with latitude (slope of curve -0.03 +/- 0.12 nmol/l per degree latitude north or south of equator, p = 0.8). There was a significant decline with latitude for Caucasians (-0.69 +/- 0.30 nmol/l per degree, p = 0.02), but not for non-Caucasians (0.03 +/- 0.39 nmol/l per degree, p = 0.14). After adjustment for age, gender, and ethnicity, no overall correlation was present between 25(OH)D and latitude (-0.29 +/- 0.24 nmol/l per degree, p = 0.23).

CONCLUSIONS

There was no overall influence of latitude on 25(OH)D. However, in separate analyses 25(OH)D decreased with latitude in Caucasians but not in non-Caucasians. A widespread global vitamin D insufficiency was present compared with proposed threshold levels.

Aberrant HCO(3)(-) transport is a hallmark of cystic fibrosis (CF) and is associated with aberrant Cl(-)-dependent HCO(3)(-) transport by the cystic fibrosis transmembrane conductance regulator (CFTR). We show here that HCO(3)(-) current by CFTR cannot account for CFTR-activated HCO(3)(-) transport and that CFTR does not activate AE1-AE4. In contrast, CFTR markedly activates Cl(-) and OH(-)/HCO(3)(-) transport by members of the SLC26 family DRA, SLC26A6 and pendrin. Most notably, the SLC26s are electrogenic transporters with isoform-specific stoichiometries. DRA activity occurred at a Cl(-)/HCO(3)(-) ratio>> or =2. SLC26A6 activity is voltage regulated and occurred at HCO(3)(-)/Cl(-)>> or =2. The physiological significance of these findings is demonstrated by interaction of CFTR and DRA in the mouse pancreas and an altered activation of DRA by the R117H and G551D mutants of CFTR. These findings provide a molecular mechanism for epithelial HCO(3)(-) transport (one SLC26 transporter-electrogenic transport; two SLC26 transporters with opposite stoichiometry in the same membrane domain-electroneutral transport), the CF-associated aberrant HCO(3)(-) transport, and reveal a new function of CFTR with clinical implications for CF and congenital chloride diarrhea.

HL-60, a cell line established from a patient with promyelocytic leukaemia, responds to a variety of inducing agents by ceasing division and acquiring some of the characteristics of either granulocytes or monocytes. Among the agents so far tested, only a comparative few occur naturally in vertebrates and would appear to have significant clinical potential in the treatment of leukaemic patients. One of the most promising of these is the dihydroxymetabolite of vitamin D3, 1,25(OH)2D3. This compound circulates in normal man and has a major role in calcium homeostasis. Moreover, it has recently been reported that 1,25(OH)2D3 increases the survival time of mice injected with myeloid leukaemia cells. We and McCarthy et al. have previously shown that HL-60 cells respond to near physiological levels of 1,25(OH)2D3 by rapidly acquiring a number of monocyte-like features. Here we document that these phenotypic changes are preceded by a marked decrement in the expression of the c-myc oncogene. In fact, the diminution in the level of c-myc mRNA parallels the dose dependency and metabolite specificity shown by the various other indicators of phenotypic change. In addition, we demonstrate that removal of vitamin D3, after the onset of maturational change, results in the reappearance of elevated myc mRNA levels. We believe this to be the first demonstration of a sequential relationship between the application of an exogenous inducing agent, a reduction in myc mRNA levels and the development of characteristics associated with normal cell maturation.

The cistron A protein induced by phage varphiX174 nicks (produces a single-strand break in) the viral strand of the superhelical varphiX duplex DNA, thereby forming a complex with the DNA. The protein, seen bound to the DNA in the electron microscope, was located in the restriction endonuclease fragment between nucleotides 4290 and 4330 on the varphiX map [Sanger, F., Air, G. M., Barrel, B. G., Brown, N. L., Coulson, A. R., Fiddes, J. C., Hutchison, C. A., III, Slocomb, P. M. Y. & Smith, M. (1977) Nature 265, 687-695]. Replication also was initiated at this point, thus identifying the site of cistron A protein nicking and binding as the origin of replication. The cisA-DNA complex (separated from free cistron A protein), upon the addition of Escherichia coli rep protein, ATP, and DNA binding protein, is unwound to generate a single-stranded linear [presumably the nicked (+) strand] and a circular [presumably the (-) strand] molecule. The cisA-DNA complex, upon the further addition of DNA polymerase III holoenzyme and deoxynucleoside triphosphates, supports replication to generate viral, single-stranded circles, as many as 15 circles per cisA-DNA complex. The replicating intermediates seen in the electron microscope are a novel form of "rolling circle" [Gilbert, W. & Dressler, D. H. (1969) Cold Spring Harbor Symp. Quant. Biol. 33, 473-485]. The 5' end (presumably with the cistron A protein bound to it) is locked in the replication fork and loops back to accompany the strand-separation and replication fork around the template [(-) strand] circle. Thus, the multiple functions of cistron A protein include: (i) nicking the viral strand at the origin of replication to initiate a round of replication, (ii) participating in a complex which supports fork movement in strand separation and replication, (iii) nicking again at the regenerated origin to produce a unit-length DNA, and (iv) ligating the newly generated 3'-OH end to the 5'-phosphate-complexed end to form a circular viral molecule.

CYP24A1 is the cytochrome P450 component of the 25-hydroxyvitamin D(3)-24-hydroxylase enzyme that catalyzes the conversion of 25-hydroxyvitamin D(3) (25-OH-D(3)) and 1,25-dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) into 24-hydroxylated products, which constitute the degradation of the vitamin D molecule. This review focuses on recent data in the CYP24A1 field, including biochemical, physiological and clinical developments. Notable among these are: the first crystal structure for rat CYP24A1; mutagenesis studies which change the regioselectivity of the enzyme; and the finding that natural inactivating mutations of CYP24A1 cause the genetic disease idiopathic infantile hypercalcemia (IIH). The review also discusses the emerging correlation between rising serum phosphate/FGF-23 levels and increased CYP24A1 expression in chronic kidney disease, which in turn underlies accelerated degradation of both serum 25-OH-D(3) and 1,25-(OH)(2)D(3) in this condition. This review concludes by evaluating the potential clinical utility of blocking this enzyme with CYP24A1 inhibitors in various disease states.

AKT2, an oncogene encoding a protein serine-threonine kinase implicated in phosphatidylinositol-3-OH kinase signaling, is amplified in some human ovarian and pancreatic carcinomas. We previously demonstrated that the tumorigenicity and invasiveness of pancreatic ductal adenocarcinoma (PDAC) cell lines with amplified AKT2 could be markedly reduced by transfection with antisense AKT2 constructs. To evaluate further the extent of AKT2 alterations in PDAC, DNA and immunohistochemical analyses were performed to assess amplification or overexpression of AKT2, respectively, in 72 PDACs. Thirty-five PDACs were subjected to Southern analyses, and AKT2 amplification was detected in seven tumors (20%). Forty-one formalin-fixed PDAC specimens were examined immunohistochemically with an anti-AKT2 monoclonal antibody, and moderate to intense staining was observed in eight tumors (20%). AKT2 immunostaining paralleled AKT2 genomic status in each of four cases in which both Southern and immunohistochemical analyses were performed. No obvious relationship was observed between AKT2 status and tumor TNM stage or grade. These observations suggest the utility of immunohistochemical analysis in assessing alterations of AKT2 in human cancers. Furthermore, the role played by the AKT2 kinase in the signaling pathways of various mitogenic growth factors implicated in the development of pancreatic cancer suggests that alteration of AKT2 may be an important component in the pathogenesis of a substantial subset of PDACs.

Several lines of evidence suggest that vitamin D may reduce incidence of breast cancer, but few epidemiologic studies have addressed the relation of plasma vitamin D metabolites to the risk of this disease. We prospectively examined the relationship between plasma levels of 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)2D] and risk of breast cancer in a case-control study nested within the Nurses' Health Study cohort. Blood samples were collected from study participants in 1989-1990. Breast cancer cases developing between blood collection and June 1, 1996, were matched to cancer-free controls on the basis of age, menopausal status, and other factors. Stored plasma samples from 701 cases and 724 controls were available for metabolite analysis. Cases had a lower mean 25(OH)D level than controls (P=0.01), but mean 1,25(OH)2D levels were similar (P=0.49). High levels of both metabolites were associated with a nonsignificant lower risk of breast cancer. Women in the highest quintile of 25(OH)D had a relative risk of 0.73 (95% confidence interval=0.49-1.07; Ptrend=0.06) compared with those in the lowest quintile. For 1,25(OH)2D, the comparable relative risk was 0.76 (95% confidence interval=0.52-1.11; Ptrend=0.39). For both metabolites, the association was stronger in women ages 60 years and older, but results were not statistically significant. Our findings suggest that high levels of 25(OH)D, and perhaps 1,25(OH)2D, may be modestly associated with reduced risk of breast cancer.

This protocol details the most commonly used nuclear magnetic resonance (NMR)-based method for deducing the configuration of otherwise unknown stereogenic, secondary carbinol (alcohol) centers (R1R2CHOH (or the analogous amines where OH is replaced by NH2)). This 'Mosher ester analysis' relies on the fact that the protons in diastereomeric alpha-methoxy-alpha-trifluoromethylphenylacetic acid (MTPA) esters (i.e., those derived from conjugation of the carbinol under interrogation with MTPA) display different arrays of chemical shifts (deltas) in their 1H NMR spectra. The protocol consists of the following: (i) preparation of each of the diastereomeric S- and R-MTPA esters and (ii) comparative (Delta delta(SR)) analysis of the 1H NMR spectral data of these two esters. By analyzing the sign of the difference in chemical shifts for a number of analogous pairs of protons (the set of Delta delta(SR) values) in the diastereomeric esters (or amides), the absolute configuration of the original carbinol (or amino) stereocenter can be reliably deduced. A typical Mosher ester analysis requires approximately 4-6 h of active effort over a 1- to 2-d period.

BACKGROUND

1,25(OH)2 vitamin D3 exerts multiple effects in human vascular smooth muscle cells (VSMCs). We therefore tested the possibility that VSMCs possess an endogenous 25-hydroxyvitamin D3-1alpha-hydroxylase system, the final enzyme in the biosynthetic pathway of 1,25(OH)2D3.

RESULTS

We assessed the expression and activity of 25-hydroxyvitamin D3-1alpha-hydroxylase by real-time polymerase chain reaction and the conversion of 25(OH)D3 into 1,25(OH)2D3. First, 25-hydroxyvitamin D3-1alpha-hydroxylase mRNA was identified in cultured VSMCs by real-time polymerase chain reaction. Second, in cells treated daily (3 days) with parathyroid hormone (66 nmol/L), estradiol-17beta (30 nmol/L), raloxifene (3 micromol/L), and the phytoestrogens genistein (3 micromol/L), biochainin A (3 micromol/L), and 6-carboxy biochainin A (30 nmol/L), 25-hydroxyvitamin D3-1alpha-hydroxylase mRNA increased by 43+/-13%, (P<0.05) 7+/-24% (P=NS), 176+/-28% (P<0.01), 65+/-11% (P<0.05), 152+/-24% (P<0.01), and 71+/-9% (P<0.05), respectively. Third, production of 1,25(OH)2D3 from 25(OH)D3 was seen with a Km of 25 ng/mL and increased dose dependently after treatment with parathyroid hormone, genistein, and the phytosetrogen derivative 6-carboxy biochainin A. Estradiol-17beta and biochainin A also increased the generation of 1,25(OH)2D3 by 40+/-23% (P<0.05) and 55+/-13% (P<0.05), respectively.

CONCLUSIONS

We provide here the first evidence for the expression of an enzymatically active 25(OH)D3-1alpha-hydroxylase system in human VSMCs, which can be upregulated by parathyroid hormone and estrogenic compounds. Because exogenous vitamin D inhibits VSMC proliferation, the role of this system as an autocrine mechanism to curb changes in VSMC proliferation and phenotype is a subject for future investigation.

OBJECTIVE

Functional neuroimaging methods have proliferated in recent years, such that functional magnetic resonance imaging, in particular, is now widely used to study bipolar disorder. However, discrepant findings are common. A workgroup was organized by the Department of Psychiatry, University of Cincinnati (Cincinnati, OH, USA) to develop a consensus functional neuroanatomic model of bipolar I disorder based upon the participants' work as well as that of others.

METHODS

Representatives from several leading bipolar disorder neuroimaging groups were organized to present an overview of their areas of expertise as well as focused reviews of existing data. The workgroup then developed a consensus model of the functional neuroanatomy of bipolar disorder based upon these data.

RESULTS

Among the participants, a general consensus emerged that bipolar I disorder arises from abnormalities in the structure and function of key emotional control networks in the human brain. Namely, disruption in early development (e.g., white matter connectivity and prefrontal pruning) within brain networks that modulate emotional behavior leads to decreased connectivity among ventral prefrontal networks and limbic brain regions, especially the amygdala. This developmental failure to establish healthy ventral prefrontal-limbic modulation underlies the onset of mania and ultimately, with progressive changes throughout these networks over time and with affective episodes, a bipolar course of illness.

CONCLUSIONS

This model provides a potential substrate to guide future investigations and areas needing additional focus are identified.

Cell proliferation is controlled not only by soluble mitogens but also by components of the extracellular matrix (ECM) such as fibronectin, to which cells adhere via the integrin family of transmembrane receptors. Input from both growth factor receptors and integrins is required to stimulate progression through the G1 phase of the cell cycle, via induction of G1 cyclins and suppression of inhibitors of the G1 cyclin-dependent kinases. Extensive crosstalk takes place between integrin and growth factor receptor signaling pathways, and mitogenic signaling is weak and transient in the absence of integrin-mediated cell adhesion. In normal untransformed cells, all of the important mitogenic signal transduction cascades, namely those downstream of the Ras and Rho family small GTPases and the phosphoinositide 3-OH kinase-PKB/Akt pathway, are regulated by integrin-mediated cell adhesion. As a result, these cells are anchorage-dependent for growth. In contrast, constitutive activity of each of these pathways has been reported in cancer cells, which not only reduces their mitogen dependence but also allows these cells to grow in an anchorage-independent fashion.

The hormonal form of vitamin D3, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], at picomolar concentrations, inhibited the growth-promoting lymphokine interleukin-2, which is produced by human T lymphocytes activated in vitro by the mitogen phytohemagglutinin. Other metabolites of vitamin D3 were less effective than 1,25(OH)2D3 in suppressing interleukin-2; their order of potency corresponded to their respective affinity for the 1,25(OH)2D3 receptor, suggesting that the effect on interleukin-2 was mediated by this specific receptor. The proliferation of mitogen-activated lymphocytes was also inhibited by 1,25(OH)2D3. This effect of the hormone became more pronounced at later stages of the culture. These findings demonstrate that 1,25(OH)2D3 is an immunoregulatory hormone.

Cytosols from cultured myoblast cells (G-8 and H9c2) prepared in high salt (0.3 M KCl) possesses receptor like proteins for 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) that sediment in the 3.2 S region of sucrose gradients. These receptors were characterized as having high affinity (Kd less than 0.1 nM) for 1,25-(OH)2D3 and are in low capacity (less than 80 fmol/mg of cytosol protein). Analog competition for receptor binding revealed that 1,25-(OH)2D3 was more potent than 24,25-(OH)2D3, or 25-(OH)2D3 for displacement of 1,25-(OH)2[3H]D3 from these 3.2 S region sedimenting receptors. Furthermore, the receptor proteins had affinity for DNA and eluted from Sephacryl S-200 as a macromolecule with Stokes radius (Rs) of 32 A. High salt cytosol from collagenase-dispersed skeletal muscle cells was also found to possess a 3.2 S 1,25-(OH)2D3 receptor-like protein. The 1,25-(OH)2D3 receptor concentration in both G-8 and H9c2 myoblast lines was found to down-regulate by 50-70% when cells were stimulated to differentiate to myotubes by lowering fetal calf serum to 5% of the medium. Moreover, we demonstrated that 1,25-(OH)2D3 can inhibit DNA synthesis and cell proliferation of the G-8 myoblast cells in a dose-dependent manner. 1,25-(OH)2D3 was more potent at inhibiting cell proliferation in cells grown in 5% serum than in 20% serum. The data suggest that 1,25-(OH)2D3 can act directly on muscle myoblast via a 1,25-(OH)2D3 receptor that is similar to those found in intestine and bone. The data support the possibility that muscle is a target tissue for 1,25-(OH)2D3 and the hormone may act to initiate terminal differentiation of myoblast cells.

BACKGROUND

Low vitamin D status has long been implicated in colorectal carcinogenesis. We investigated this relationship in a nested case-control study within the Health Professionals Follow-up Study (HPFS), a large ongoing study of male health professionals living in the United States.

METHODS

Between 1993 and 2002, 179 colorectal cancer patients were diagnosed and matched to 356 control subjects by age and by month and year of blood collection. Results were also pooled with previously published results from the Nurses' Health Study (NHS) cohort, a large female cohort. Conditional logistic regression was used to analyze the association between plasma 25-hydroxyvitamin D [25(OH)D] and colorectal cancer, and pooled estimates were calculated using the method of DerSimonian and Laird. All statistical tests were two-sided.

RESULTS

In the HPFS, we observed a non-statistically significant inverse association between higher plasma 25(OH)D concentration and risk of colorectal cancer and a statistically significant inverse association for colon cancer (highest versus lowest quintile: odds ratio [OR] = 0.46, 95% confidence interval [CI] = 0.24 to 0.89; P(trend) = .005). After pooling the results from the HPFS and NHS, higher plasma 25(OH)D concentrations were statistically significantly associated with decreased risks of both colorectal cancer (highest versus lowest quintile, OR = 0.66, 95% CI = 0.42 to 1.05; P(trend) = .01) and colon cancer (highest versus lowest quintile, OR = 0.54, 95% CI = 0.34 to 0.86; P(trend) = .002). Inverse associations with plasma 25(OH)D concentration did not differ by location of colon cancer (proximal versus distal), but the number of patients was small and none of the associations was statistically significant. Opposite relationships between plasma 25(OH)D levels and risk of rectal cancers were found among men (positive) and women (inverse).

CONCLUSIONS

Our data provide additional support for the inverse association between vitamin D and colorectal and, in particular, colon cancer risk.

Polycystic ovary syndrome (PCOS) is a heterogeneous disorder of reproductive age women characterized in its broadest definition by the presence of oligoamenorrhea and hyperandrogenism and the absence of other disorders. Defects of gonadotropin secretion, including an elevated LH level, elevated LH to FSH ratio, and an increased frequency and amplitude of LH pulsations have been described, but the prevalence of these defects in a large, unbiased population of PCOS patients has not been determined. Sixty-one women with PCOS defined by oligomenorrhea and hyperandrogenism and 24 normal women in the early follicular phase had LH samples obtained every 10 min for 8-12 h. Pool LH levels from the frequent sampling studies were within the normal range in the 9 PCOS patients (14.8%) who were studied within 21 days after a documented spontaneous ovulation. Excluding these post-ovulatory patients, 75.0% of the PCOS patients had an elevated pool LH level (above the 95th percentile of the normal controls), and 94% had an elevated LH to FSH ratio. In the anovulatory PCOS patients, pool LH correlated positively with 17-OH progesterone (R = 0.30, P = 0.03), but not with estradiol, estrone, testosterone, androstenedione, or DHEA-S. Pool LH and LH to FSH ratio correlated positively with LH pulse frequency (R = 0.40, P = 0.004 for pool LH, and R = 0.39; P = 0.005 for LH/FSH). There was also a strong negative correlation between pool LH and body mass index (BMI) (R = -0.59, P < 10(-5)). The relationship between BMI and LH secretion in the PCOS patients appeared to be strongest with body fatness, as pool LH was correlated inversely with percent body fat, whether measured by skinfolds (R = -0.61, P < 10(-5)), bioimpedance (R = -0.55, P < 10(-4)), or dual energy x-ray absorptiometry (DEXA) (R = -0.70, P = 0.001; n = 18 for DEXA only). By DEXA, the only body region that was highly correlated with pool LH was the trunk (R = -0.71, P = 0.001). The relationship between body fatness and LH secretion occurred via a decrease in LH pulse amplitude (R = -0.63, P < 10(-5) for BMI; R = -0.58, P < 10(-4) for bioimpedance; and R = -0.64, P = 0.004 for whole body DEXA), with no significant change in pulse frequency with increasing obesity (R = -0.17, P = 0.23 for BMI).

CONCLUSIONS

1) the prevalence of gonadotropin abnormalities is very high in women with PCOS selected on purely clinical grounds, but is modified by recent spontaneous ovulation; 2) the positive relationship between LH pulse frequency and both pool LH and LH to FSH ratio supports the hypothesis that a rapid frequency of GnRH secretion may play a key etiologic role in the gonadotropin defect in PCOS patients; 3) pool LH and LH pulse amplitude are inversely related to body mass index and percent body fat in a continuous fashion; and 4) the occurrence of a continuous spectrum of gonadotropin abnormalities varying with body fat suggests that nonobese and obese patients with PCOS do not represent distinct pathophysiologic subsets of this disorder.

Allergen-induced secretion of Th2-type cytokines and IgE production have recently been reported to be increased in mice treated with 1,25(OH)(2)D, the active form of vitamin D. Our objective was to investigate whether vitamin D supplementation in infancy is associated with the risk of atopy, allergic rhinitis, and asthma. The Northern Finland Birth Cohort consists of all individuals in the two most northern provinces of Finland who were due to be born in 1966. Data on vitamin D supplementation during the first year of life was obtained in 1967. Current asthma and allergic rhinitis were reported at age 31 years (n = 7,648), and atopy determined by skin-prick test in a sub-sample still living in northern Finland or the Helsinki area (n = 5,007). The prevalence of atopy and allergic rhinitis at age 31 years was higher in participants who had received vitamin D supplementation regularly during the first year compared to others (OR 1.46, 95%CI 1.4-2.0, and OR 1.66, 95%CI 1.1-1.6, respectively). A similar association was observed for asthma (OR 1.35, 95%CI 0.99-1.8). These associations persisted after adjustment for a wide range of behavioral and social factors (adjusted: OR 1.33 for all, P = 0.01 for atopy, P = 0.001 for allergic rhinitis, and P = 0.08 for asthma). We observed an association between vitamin D supplementation in infancy and an increased risk of atopy and allergic rhinitis later in life. Further study is required to determine whether these observations reflect long-term effects on immune regulation or differences in unmeasured determinants of vitamin D supplementation.

BACKGROUND

Vitamin D deficiency is associated with many adverse health outcomes, yet little is known about the genetic epidemiology of vitamin D or its metabolites.

OBJECTIVE

Our objective was to examine the relationship among three vitamin D-related genes and levels of 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)2D] in Hispanics (HAs) and African Americans (AAs).

METHODS

The cross-sectional Insulin Resistance Atherosclerosis Family Study recruited and examined subjects in: Los Angeles, California (AAs; 513 individuals from 42 families); San Luis Valley (SLV), Colorado (HAs; 513 individuals from 30 families); and San Antonio (SA), Texas (HAs; 504 individuals from 58 families).

METHODS

Plasma levels of 25(OH)D and 1,25(OH)2D were measured.

RESULTS

Levels of 25(OH)D were highest in SLV-HAs [18.3 +/- 7.7 ng/ml (45.7 +/- 19.2 nmol/liter)], lower in SA-HAs [14.6 +/- 6.4 ng/ml (36.4 +/- 16.0 nmol/liter)], and lowest in AAs [11.0 +/- 5.4 ng/ml (27.5 +/- 13.5 nmol/liter)]. Levels of 1,25(OH)2D were similar in AAs [43.5 +/- 13.9 pg/ml (113.1 +/- 36.1 pmol/liter)] and SLV-HAs [43.2 +/- 13.3 pg/ml (112.3 +/- 34.6 pmol/liter)], but higher in SA-HAs [48.6 +/- 17.0 pg/ml (126.4 +/- 44.2 pmol/liter)]. After adjusting for gender and age within the site, two single nucleotide polymorphisms (SNPs) in the vitamin D binding protein gene (DBP), rs4588 and rs7041, were associated with 25(OH)D, and one SNP in the DBP, rs4588, was associated with 1,25(OH)2D at all three study centers.

CONCLUSIONS

SNPs in the DBP are associated with levels of 25(OH)D and 1,25(OH)2D in HA and AA participants in the Insulin Resistance Atherosclerosis Family Study.