The main role of vitamin D: Seasonal regulation of vital functions. High-resolution target recognition leads to a new paradigm and advanced drug development

2007 ◽  
Vol 32 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Walter E. Stumpf
Keyword(s):  
Vitamin D ◽  
High Resolution ◽  
Drug Development ◽  
Target Recognition ◽  
Main Role ◽  
New Paradigm ◽  
Vital Functions ◽  
Seasonal Regulation

scholarly journals In sickness and in health: pivotal role of vitamin D

2020 ◽  
Vol 30 (2) ◽  
pp. 202-214 ◽  
Author(s):  
Nora Nikolac Gabaj ◽  
Tomislav Pavicic ◽  
Alen Vrtaric ◽  
Lara Milevoj Kopcinovic ◽  
Davorka Herman Mahecic ◽  
...  
Keyword(s):  
Vitamin D ◽  
Vitamin D Supplementation ◽  
Main Role ◽  
Vitamin D Metabolites ◽  
Gold Standard Method ◽  
Liquid Chromatography Tandem Mass ◽  
First Results ◽  
Preanalytical Variability ◽  
Open Question

Within the last several years, frequency of vitamin D testing has multiplied substantially all over the world, since it has been shown to have an important role in many diseases and conditions. Even though liquid chromatography - tandem mass spectrometry (LC-MS/MS) has been identified as “gold standard” method for vitamin D measurement, most laboratories still use immunochemistry methods. Besides analytical problems (hydrophobicity, low circulating concentrations, ability to bind to lipids, albumins and vitamin D binding protein, presence of multiple vitamin D metabolites and variable ratios of 25(OH)D2 and 25(OH)D3 in the blood), vitamin D shows great preanalytical variability, since its concentration is drastically influenced by seasonal changes, exposure to sun, type of clothes or sun block creams. Vitamin D is mostly measured in serum or plasma, but new studies are showing importance of measuring vitamin D in pleural effusions, breast milk, urine, synovial fluid and saliva. Besides the main role in calcium homeostasis and bone metabolism, many studies linked vitamin D deficiency with cancer, cardiovascular diseases, diabetes, fertility and many other conditions. However, even though initial observational studies indicated that supplementation with vitamin D might be beneficial in disease development and progression; first results of well-designed randomized controlled prospective studies did not find differences in frequency of cardiovascular events or invasive cancer between patients taking vitamin D supplementation compared to placebo. In the light of these recent findings, validity of excessive vitamin D testing remains an open question.

scholarly journals Liprin-α/SYD-2 determines the size of dense projections in presynaptic active zones in C. elegans

2013 ◽  
Vol 203 (5) ◽  
pp. 849-863 ◽  
Author(s):  
Maike Kittelmann ◽  
Jan Hegermann ◽  
Alexandr Goncharov ◽  
Hidenori Taru ◽  
Mark H. Ellisman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Caenorhabditis Elegans ◽  
High Resolution ◽  
Active Zone ◽  
Neuromuscular Junctions ◽  
Main Role ◽  
C Elegans ◽  
Active Zones ◽  
Dense Projections

Synaptic vesicle (SV) release is spatially and temporally regulated by a network of proteins that form the presynaptic active zone (AZ). The hallmark of most AZs is an electron-dense projection (DP) surrounded by SVs. Despite their importance for our understanding of triggered SV release, high-resolution analyses of DP structures are limited. Using electron microscopy, we show that DPs at Caenorhabditis elegans neuromuscular junctions (NMJs) were highly structured, composed of building units forming bays in which SVs are docked to the AZ membrane. Furthermore, larger ribbonlike DPs that were multimers of the NMJ building unit are found at synapses between inter- and motoneurons. We also demonstrate that DP size is determined by the activity of the AZ protein SYD-2/Liprin-α. Whereas loss of syd-2 function led to smaller DPs, syd-2 gain-of-function mutants displayed larger ribbonlike DPs through increased recruitment of ELKS-1/ELKS. Therefore, our data suggest that a main role of SYD-2/Liprin-α in synaptogenesis is to regulate the polymerization of DPs.

scholarly journals The Usefulness of Serum Vitamin D Levels in the Assessment of IBD Activity and Response to Biologics

Nutrients ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 323
Author(s):  
Marco Valvano ◽  
Marco Magistroni ◽  
Antonio Mancusi ◽  
Debora D’Ascenzo ◽  
Salvatore Longo ◽  
...  
Keyword(s):  
Vitamin D ◽  
Clinical Response ◽  
Roc Analysis ◽  
Serum Vitamin ◽  
Main Role ◽  
Biological Drugs ◽  
Serum Vitamin D ◽  
Vitamin D Levels ◽  
Histological Activity

The main role of vitamin D is calcium homeostasis and bone metabolism, although its activity as an immuno-modulator and its anti-inflammatory effect is well-known. Low blood vitamin D levels are common among patients with inflammatory bowel disease (IBD). Whether low vitamin D levels could affect the disease activity or it is an effect of a worse condition of the disease is still unclear. This study aimed to investigate the role of blood vitamin D levels to identify the clinical, endoscopic, and histological activity in a cohort of patients with ulcerative colitis (UC) or Crohn’s disease (CD) on therapy with biological drugs. In this retrospective cohort study, 50 IBD patients (24 UC and 26 CD) that underwent colonoscopy from January 2017 to January 2020 with a concomitant serological evaluation of vitamin D were included. Patients with clinical, endoscopic, and histological activity and those who lost their clinical response to the biological drug had lower vitamin D levels compared to patients in remission or patients that did not change therapeutic regimens. A receiver operating characteristic (ROC) analysis and Youden’s Index were performed to assess the optimal vitamin D levels to identify patients with the active disease. The ROC analysis showed an area under the curve (AUC) of 0.709 (p = 0.005; confidence interval (CI): 0.564–0.829), 0.769 (p < 0.001; CI: 0.628–0.876), and 0.810 (p < 0.001; CI: 0.670–0.910) for the clinical, endoscopic, and histological outcomes, respectively. The optimal vitamin D cut-off was ≤25 ng/mL. The vitamin D level is an additional useful tool in the evaluation of IBD patients with good accuracy to predict their endoscopic and histological activity and clinical response to biologics.

Role of spectrin in membrane fusion and in shape change of human erythrocyte ghost

1978 ◽  
Vol 36 (2) ◽  
pp. 328-329
Author(s):  
Hideo Hayashi ◽  
Yoshikazu Hirai ◽  
John T. Penniston
Keyword(s):  
Conformational Changes ◽  
Human Erythrocyte ◽  
Shape Change ◽  
Membrane Surface ◽  
Slight Modification ◽  
Active Role ◽  
Main Role ◽  
Bank Blood ◽  
Human Erythrocyte Ghost

Spectrin is a membrane associated protein most of which properties have been tentatively elucidated. A main role of the protein has been assumed to give a supporting structure to inside of the membrane. As reported previously, however, the isolated spectrin molecule underwent self assemble to form such as fibrous, meshwork, dispersed or aggregated arrangements depending upon the buffer suspended and was suggested to play an active role in the membrane conformational changes. In this study, the role of spectrin and actin was examined in terms of the molecular arrangements on the erythrocyte membrane surface with correlation to the functional states of the ghosts.Human erythrocyte ghosts were prepared from either freshly drawn or stocked bank blood by the method of Dodge et al with a slight modification as described before. Anti-spectrin antibody was raised against rabbit by injection of purified spectrin and partially purified.

Mesophyll conductance: the leaf corridors for photosynthesis

2020 ◽  
Vol 48 (2) ◽  
pp. 429-439 ◽  
Author(s):  
Jorge Gago ◽  
Danilo M. Daloso ◽  
Marc Carriquí ◽  
Miquel Nadal ◽  
Melanie Morales ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Main Role ◽  
Mesophyll Conductance ◽  
Future Studies ◽  
Cell Structures ◽  
Leaf Tissues ◽  
Change Framework ◽  
Chloroplast Stroma

Besides stomata, the photosynthetic CO2 pathway also involves the transport of CO2 from the sub-stomatal air spaces inside to the carboxylation sites in the chloroplast stroma, where Rubisco is located. This pathway is far to be a simple and direct way, formed by series of consecutive barriers that the CO2 should cross to be finally assimilated in photosynthesis, known as the mesophyll conductance (gm). Therefore, the gm reflects the pathway through different air, water and biophysical barriers within the leaf tissues and cell structures. Currently, it is known that gm can impose the same level of limitation (or even higher depending of the conditions) to photosynthesis than the wider known stomata or biochemistry. In this mini-review, we are focused on each of the gm determinants to summarize the current knowledge on the mechanisms driving gm from anatomical to metabolic and biochemical perspectives. Special attention deserve the latest studies demonstrating the importance of the molecular mechanisms driving anatomical traits as cell wall and the chloroplast surface exposed to the mesophyll airspaces (Sc/S) that significantly constrain gm. However, even considering these recent discoveries, still is poorly understood the mechanisms about signaling pathways linking the environment a/biotic stressors with gm responses. Thus, considering the main role of gm as a major driver of the CO2 availability at the carboxylation sites, future studies into these aspects will help us to understand photosynthesis responses in a global change framework.

The role of vitamin D in metabolic and reproductive disturbances of polycystic ovary syndrome: A narrative mini-review

2020 ◽  
pp. 1-8
Author(s):  
Daniela Menichini ◽  
Gianpiero Forte ◽  
Beatrice Orrù ◽  
Giuseppe Gullo ◽  
Vittorio Unfer ◽  
...  
Keyword(s):  
Vitamin D ◽  
Polycystic Ovary Syndrome ◽  
Embryo Quality ◽  
Polycystic Ovary ◽  
Vitamin D Supplementation ◽  
Endometrial Receptivity ◽  
Metabolic Disturbances ◽  
Ovary Syndrome ◽  
Beneficial Role

Abstract. Vitamin D is a secosteroid hormone that plays a pivotal role in several metabolic and reproductive pathways in humans. Increasing evidence supports the role of vitamin D deficiency in metabolic disturbances and infertility in women with polycystic ovary syndrome (PCOS). Indeed, supplementation with vitamin D seems to have a beneficial role on insulin resistance and endometrial receptivity. On the other hand, exceedingly high levels of vitamin D appear to play a detrimental role on oocytes development and embryo quality. In the current review, we summarize the available evidence about the topic, aiming to suggest the best supplementation strategy in women with PCOS or, more generally, in those with metabolic disturbances and infertility. Based on the retrieved data, vitamin D seems to have a beneficial role on IR, insulin sensitivity and endometrial receptivity, but high levels and incorrect timing of administration seem to have a detrimental role on oocytes development and embryo quality. Therefore, we encourage a low dose supplementation (400–800 IU/day) particularly in vitamin D deficient women that present metabolic disturbances like PCOS. As far as the reproductive health, we advise vitamin D supplementation in selected populations, only during specific moments of the ovarian cycle, to support the luteal phase. However, ambiguities about dosage and timing of the supplementation still emerge from the clinical studies published to date and further studies are required.

Quantitative accuracy of serotonergic neurotrans-mission imaging with high-resolution 123I SPECT

2004 ◽  
Vol 43 (06) ◽  
pp. 185-189 ◽  
Author(s):  
J. T. Kuikka
Keyword(s):  
High Resolution ◽  
Scatter Correction ◽  
Region Of Interest ◽  
Binding Potential ◽  
Partial Volume ◽  
Therapeutic Drugs ◽  
Quantitative Accuracy ◽  
Critical Error ◽  
Statistical Noise

Summary Aim: Serotonin transporter (SERT) imaging can be used to study the role of regional abnormalities of neurotransmitter release in various mental disorders and to study the mechanism of action of therapeutic drugs or drugs’ abuse. We examine the quantitative accuracy and reproducibility that can be achieved with high-resolution SPECT of serotonergic neurotransmission. Method: Binding potential (BP) of 123I labeled tracer specific for midbrain SERT was assessed in 20 healthy persons. The effects of scatter, attenuation, partial volume, mis-registration and statistical noise were estimated using phantom and human studies. Results: Without any correction, BP was underestimated by 73%. The partial volume error was the major component in this underestimation whereas the most critical error for the reproducibility was misplacement of region of interest (ROI). Conclusion: The proper ROI registration, the use of the multiple head gamma camera with transmission based scatter correction introduce more relevant results. However, due to the small dimensions of the midbrain SERT structures and poor spatial resolution of SPECT, the improvement without the partial volume correction is not great enough to restore the estimate of BP to that of the true one.

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