Calcitriol improves streptozotocin-induced diabetes and recovers bone mineral density in diabetic rats.

Vitamin D analogs exert a preventative effect on experimental diabetes, but whether or not they are able to halt progress of established diabetes is not yet known. Moreover, it is widely accepted that diabetes may induce osteoporosis, but the efficacy of vitamin D on diabetic osteoporosis is not clear. In order to help clarify these issues, we have tested the efficacy of calcitriol streptozotocin-induced diabetes.

1,25-Dihydroxyvitamin D3 modulates expression of chemokines and cytokines in pancreatic islets: implications for prevention of diabetes in nonobese diabetic mice.

1,25-Dihydroxyvitamin D(3) (1,25-(OH)(2)D(3)) is an immune modulator that prevents experimental autoimmune diseases. Receptors for 1,25-(OH)(2)D(3) are present in pancreatic beta-cells, the target of an autoimmune assault in nonobese diabetic (NOD) mice. The aim of this study was to investigate the in vivo and in vitro effects of 1,25-(OH)(2)D(3) on beta-cell gene expression and death and correlate these findings to in vivo diabetes development in NOD mice.

Estrogens are essential for male pubertal periosteal bone expansion.

The skeletal response to estrogen therapy was studied in a 17-yr-old boy with congenital aromatase deficiency. As expected, estrogen therapy (1 mg estradiol valeriate/d from age 17 until 20 yr) normalized total and free testosterone and reduced the rate of bone remodeling. Dual-energy x-ray absorptiometry-assessed areal bone mineral density (BMD) of the lumbar spine and femoral neck increased significantly (by 23% and 14%, respectively), but peripheral quantitative computed tomography at the ultradistal radius revealed no gain of either trabecular or cortical volumetric BMD.

Evidence from data searches and life-table analyses for gender-related differences in absolute risk of hip fracture after Colles' or spine fracture: Colles' fracture as an early and sensitive marker of skeletal fragility in white men.

Unlabelled: Based on data searches and life-table analyses, we determined the long-term (remaining lifetime) and short-term (10- and 5-year) absolute risks of hip fracture after sustaining a Colles' or spine fracture and searched for potential gender-related differences. In aging men, Colles' fractures carry a higher absolute risk for hip fracture than spinal fractures in contrast to women. These findings support the concept that forearm fracture is an early and sensitive marker of male skeletal fragility.

Bone status and fracture prevalence in Russian adults with childhood-onset growth hormone deficiency.

The consequences of lifelong untreated childhood-onset GH deficiency (COGHD) on adult bone and especially fracture prevalence are largely unknown due to the lack of data on long-term outcome of untreated patients. Therefore, we studied adult Russian patients (n = 66; 28 females and 38 males) with idiopathic GH-untreated COGHD. Patients had isolated GH deficiency (IGHD; n = 18, age 23 +/- 10 yr) or multiple pituitary hormone deficiency (MPHD) with open (OMPHD; n = 27, age 23 +/- 5 yr) or closed growth plates (CMPHD; n = 21, age 55 +/- 12 yr).

Molecular pathways involved in the anti-apoptotic effect of 1,25-dihydroxyvitamin D3 in primary human keratinocytes.

We previously reported that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] protects primary human keratinocytes against ultraviolet (UV)B-induced apoptosis. Here, we confirmed the anti-apoptotic effect of 1,25(OH)2D3 in keratinocytes, using cisplatin and doxorubicin as apoptotic triggers. We further showed that 1,25(OH)2D3 activates two survival pathways in keratinocytes: the MEK/extracellular signal regulated kinase (ERK) and the phosphatidylinositol 3-kinase (PI-3K)/Akt pathway.

Chemoenzymatic synthesis and biological evaluation of C-3 carbamate analogues of 1alpha,25-dihydroxyvitamin D3.

The synthesis of new analogues of 1alpha,25-dihydroxyvitamin D3 containing a carbamate function at the A-ring fragment has been described using the cross-coupling approach. The carbamate group was selectively introduced at the C-3 position by regioselective enzymatic alkoxycarbonylation of A-ring enyne 3 and subsequent treatment with ammonia, amines, amino alcohols, and amino acids. Biological studies to evaluate the potency of all five of these carbamate analogues were performed and demonstrated very low binding affinity for the vitamin D receptor compared with 1alpha,25-dihydroxyvitamin D3.

Primary hyperparathyroidism: diagnosis and management in the older individual.

As more and more cases of primary hyperparathyroidism are being detected by screening for serum calcium concentration, the majority of patients are older individuals who are asymptomatic or have symptoms which are difficult to ascribe to hyperparathyroidism. Long-term follow-up has provided evidence that most asymptomatic patients who do not undergo parathyroidectomy will not develop symptomatic complications. Some asymptomatic patients, however, have progression of disease over time.

Role of the androgen receptor in skeletal homeostasis: the androgen-resistant testicular feminized male mouse model.

Unlabelled: The role of androgen receptor-mediated androgen action on bone was investigated in testicular feminized male (Tfm) mice. Cortical bone was found to be unresponsive to testosterone (T) in orchidectomized Tfm mice, whereas cortical thickness as well as trabecular BMD and structure were fully maintained by T in the corresponding Tabby control mice. These data show an essential role for androgen receptor-mediated androgen action in periosteal bone formation.

Does the phosphate binder lanthanum carbonate affect bone in rats with chronic renal failure?

Adequate control of phosphate levels remains an important issue in patients with chronic renal failure (CRF). Lanthanum carbonate has been proposed as a new phosphate binder. Previous studies have shown a high phosphate binding capacity (>97%) and low gastrointestinal absorption of lanthanum, without serious toxic side effects in the presence of a normal renal function (NRF).

NOD macrophages produce high levels of inflammatory cytokines upon encounter of apoptotic or necrotic cells.

During the development of type 1 diabetes, pancreatic beta-cells are subject to an immune attack, leading to their apoptotic or necrotic cell death. Apoptotic beta-cells are also present during periods of tissue remodeling, such as in early life. Macrophages should clear apoptotic cells silently without production of pro-inflammatory cytokines.

NOD bone marrow-derived dendritic cells are modulated by analogs of 1,25-dihydroxyvitamin D3.

The immune effects of 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) are mainly mediated through dendritic cells (DCs). In vitro, 1,25(OH)(2)D(3) treatment renders murine bone marrow (BM)-derived DCs more tolerogenic, indirectly altering behavior and fate of T lymphocytes. In vivo, treatment with 1,25(OH)(2)D(3) or its analogs prevents diabetes in NOD mice.

Regulation of 25-hydroxyvitamin d-1alpha-hydroxylase by IFNgamma in human monocytic THP1 cells.

1,25-DihydroxyVitamin D(3) (1,25(OH)(2)D(3)), a molecule with well-known actions in bone and mineral homeostasis, also plays a role in the immune system. Indeed, the receptor for 1,25(OH)(2)D(3) is found in most immune cells and important immunological effects have been described in vitro, reflected by its capacity to prevent autoimmunity and to prolong graft survival. The aim of this study was to elucidate the intracellular pathways used by the immune system to regulate 1,25(OH)(2)D(3) production.

Vitamin D and 1,25-dihydroxyvitamin D3 as modulators in the immune system.

Treatment from weaning until old age with 1,25-dihydroxyvitamin D (1,25(OH)(2)D(3)) prevents diabetes in NOD mice. It is mainly through its actions on dendritic cells (DCs), that 1,25(OH)(2)D(3) changes the function of potentially autoreactive T lymphocytes. In contrast, early life treatment (from 3 to 70 days of age) of NOD mice with vitamin D or 1,25(OH)(2)D(3) did not influence final diabetes incidence at 200 days of age.

Microarray analysis of 1alpha,25-dihydroxyvitamin D3-treated MC3T3-E1 cells.

The active form of Vitamin D, 1alpha,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)], demonstrates potent antiproliferative actions on normal as well as on malignant cell types by blocking the transition from the G1- to the S-phase of the cell cycle. Key target genes for 1,25-(OH)(2)D(3) in this non-classic effect remain largely unknown. Therefore, this study aims to identify genes that, through changes in expression after 1,25-(OH)(2)D(3) treatment, contribute to the observed antiproliferative effect.

Biological activity and conformational analysis of C20 and C14 epimers of CD-ring modified trans-decalin 1alpha,25-dihydroxyvitamin D analogs.

In the context of our ongoing study of vitamin D structure-function relationships and in an attempt to obtain a better dissociation of their prodifferentiating (HL-60) and/or antiproliferative (MCF-7) activities and their calcemic activity, further 20-epi and 14-epi modifications were made to three trans-decalin CD-ring analogs of 1,25-dihydroxyvitamin D(3), the hormonally active metabolite of vitamin D(3), possessing a natural 20R side chain and featuring additional structural modifications in the seco-B-ring and in the A-ring. Following a previously observed trend and in agreement with the conformational analysis results, all three 20-epi derivatives show substantially lower biological activities, opposite to what is usually observed for analogs having the natural CD-ring. The 14-epi modification (cis-decalins) has little effect on the biological activity of the ynediene type and the saturated derivative, but results in an approximate 10-fold reduction in activity of the previtamin derivative.

Synthesis and biological activity of 22-oxa CD-ring modified analogues of 1alpha,25-dihydroxyvitamin D3: spiro[5.5]undecane CF-ring analogues.

The synthesis and biological activity of novel CD-ring modified analogues of 22-oxa-1alpha,25-dihydroxyvitamin D(3), lacking the D-ring and featuring a connection between C-18 and C-21 (spiro[5.5]undecane CF-ring analogues), is described. The central ring system is conveniently synthesised from an achiral intermediate.

Synthesis and biological activity of 22-oxa CD-ring modified analogues of 1alpha,25-dihydroxyvitamin D3: cis-perhydrindane CE-ring analogues.

The synthesis and biological activity of novel CD-ring modified analogues of 22-oxa-1alpha,25-dihydroxyvitamin D(3), lacking the D-ring and featuring a connection between C-12 and C-21 (cis-perhydrindane CE-ring analogues), is described. The synthesis of the CE-ring system follows Meyers' methodology for the preparation of enantiomerically pure hydrinden-2-ones. The analogues show a complete lack of binding affinity for the vitamin D receptor (pig nVDR) and of antiproliferative activity (MCF-7 cells), as compared to calcitriol.

AKT status controls susceptibility of malignant keratinocytes to the early-activated and UVB-induced apoptotic pathway.

In previous work, we have described an early-activated and ultraviolet B (UVB)-induced apoptotic pathway in human keratinocytes, which can be completely inhibited by AKT activation. We now compared this response of primary human keratinocytes with the response of two p53-mutated squamous cell carcinoma (SCC)-derived cell lines (A431 and A253) to an apoptotic UVB dose. In these cell lines, both the basal AKT phosphorylation status and the apoptotic response to UVB diverged strongly from the response of healthy primary keratinocytes.

Androgens and bone.

Loss of estrogens or androgens increases the rate of bone remodeling by removing restraining effects on osteoblastogenesis and osteoclastogenesis, and also causes a focal imbalance between resorption and formation by prolonging the lifespan of osteoclasts and shortening the lifespan of osteoblasts. Conversely, androgens, as well as estrogens, maintain cancellous bone mass and integrity, regardless of age or sex. Although androgens, via the androgen receptor (AR), and estrogens, via the estrogen receptors (ERs), can exert these effects, their relative contribution remains uncertain.

Neuroendocrine tumor markers and enterochromaffin-like cell hyper/dysplasia in type 1 diabetes.

Objective: Parietal cell antibodies (PCAs) are found in 20% of type 1 diabetic patients, denoting autoimmune gastritis and pernicious anemia, which may predispose to enterochromaffin-like (ECL) cell hyper/dysplasia and gastric carcinoid tumors. We evaluated whether chromogranin A (CgA), 5-hydroxyindole acetic acid (5-HIAA), and neuron-specific enolase (NSE) contribute to screening for ECL cell hyper/dysplasia.

Research Design And Methods: Sera from 93 type 1 diabetic patients (53 men and 40 women, 31 PCA(+) and 62 PCA(-), aged 45 +/- 13 years) were analyzed for PCAs by indirect immunofluorescence and for CgA, NSE, and gastrin by radioimmunoassay.

Two 14-epi analogues of 1,25-dihydroxyvitamin D3 protect human keratinocytes against the effects of UVB.

In search of photoprotective agents, we recently demonstrated a protective effect of 1,25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] against different events mediated by ultraviolet B (UVB) in human keratinocytes. Pharmacological doses of 1,25(OH)(2)D(3) were required to obtain significant UVB protection; however, these doses cannot be used in vivo due to the calcemic properties of 1,25(OH)(2)D(3). Therefore, we evaluated the photoprotective capacities of two low-calcemic 14-epi analogues of 1,25(OH)(2)D(3), 19-nor-14-epi-23-yne-1,25(OH)(2)D(3) (TX 522) and 19-nor-14,20-bisepi-23-yne-1,25(OH)(2)D(3) (TX 527).

Vitamin D deficiency in early life accelerates Type 1 diabetes in non-obese diabetic mice.

Aims/hypothesis: 1,25-dihydroxyvitamin D(3), the active form of vitamin D, prevents Type 1 diabetes in non-obese diabetic (NOD) mice. Epidemiological data show a threefold increase in human Type 1 diabetes when vitamin D deficiency was present in the first months of life. To evaluate whether a similar dietary deficiency affects diabetes incidence in NOD mice, we generated NOD mice with vitamin D deficiency in early life.

The effects of 1alpha,25-dihydroxyvitamin D3 on the expression of DNA replication genes.

Unlabelled: To identify key genes in the antiproliferative action of 1,25(OH)2D3, MC3T3-E1 mouse osteoblasts were subjected to cDNA microarray analyses. Eleven E2F-driven DNA replication genes were downregulated by 1,25(OH)2D3. These results were confirmed by quantitative RT-PCR in different cell types, showing the general nature of this action of 1,25(OH)2D3.