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Fulltext Contribution of Coiled-Coil Assembly to Ca2+/Calmodulin-Dependent Inactivation of TRPC6 Channel and its Impacts on FSGS-Associated Phenotypes

Polat OK, Uno M, Maruyama T, Tran HN, Imamura K, Wong CF, et al.

J Am Soc Nephrol, 2019 09;30(9):1587-1603.
PMID: 31266820 DOI: 10.1681/ASN.2018070756

BACKGROUND: TRPC6 is a nonselective cation channel, and mutations of this gene are associated with FSGS. These mutations are associated with TRPC6 current amplitude amplification and/or delay of the channel inactivation (gain-of-function phenotype). However, the mechanism of the gain-of-function in TRPC6 activity has not yet been clearly solved.
METHODS: We performed electrophysiologic, biochemical, and biophysical experiments to elucidate the molecular mechanism underlying calmodulin (CaM)-mediated Ca2+-dependent inactivation (CDI) of TRPC6. To address the pathophysiologic contribution of CDI, we assessed the actin filament organization in cultured mouse podocytes.
RESULTS: Both lobes of CaM helped induce CDI. Moreover, CaM binding to the TRPC6 CaM-binding domain (CBD) was Ca2+-dependent and exhibited a 1:2 (CaM/CBD) stoichiometry. The TRPC6 coiled-coil assembly, which brought two CBDs into adequate proximity, was essential for CDI. Deletion of the coiled-coil slowed CDI of TRPC6, indicating that the coiled-coil assembly configures both lobes of CaM binding on two CBDs to induce normal CDI. The FSGS-associated TRPC6 mutations within the coiled-coil severely delayed CDI and often increased TRPC6 current amplitudes. In cultured mouse podocytes, FSGS-associated channels and CaM mutations led to sustained Ca2+ elevations and a disorganized cytoskeleton.
CONCLUSIONS: The gain-of-function mechanism found in FSGS-causing mutations in TRPC6 can be explained by impairments of the CDI, caused by disruptions of TRPC's coiled-coil assembly which is essential for CaM binding. The resulting excess Ca2+ may contribute to structural damage in the podocytes.

Matched MeSH terms: Calcium/metabolism*
Fulltext Habitat segregation and migration in tropical anguillid eels, Anguilla bengalensis bengalensis and A. bicolor bicolor

Arai T, Chai IJ, Iizuka Y, Chang CW

Sci Rep, 2020 10 09;10(1):16890.
PMID: 33037236 DOI: 10.1038/s41598-020-72788-9

Anguillid eels of the genus Anguilla, which have a unique catadromous life history, are widely distributed across many parts of the world. However, little research has been conducted on the behavioural mechanisms of habitat segregation between sympatric species in tropical anguillid eels. To understand the ecological and behavioural mechanisms involved in the life history and migration of tropical anguillid eels, strontium (Sr):calcium (Ca) ratios were examined in otoliths of A. bengalensis bengalensis (41 specimens) and A. bicolor bicolor (130 specimens) collected from ten rivers in northwestern Peninsular Malaysia. The otolith Sr:Ca ratios revealed different habitat use between the two species. The broad range of otolith Sr:Ca ratios and habitat shift found in A. bicolor bicolor suggested that its habitat utilization was opportunistic in environments of varying salinity. A. bicolor bicolor prefers to live in the midstream to downstream areas with tidal influences. A. bengalensis bengalensis, however, was found to only reside in freshwater environments throughout their continental growth. A. bengalensis bengalensis tends to live in upstream area with no tidal influence. Their habitat use, migratory history, and habitat distribution indicate that habitat segregation occurs between the two species, leading to the different habitat preferences in tropical river systems.

Matched MeSH terms: Calcium/metabolism
Fulltext Enhancement of mesenchymal stem cell chondrogenesis with short-term low intensity pulsed electromagnetic fields

Parate D, Franco-Obregón A, Fröhlich J, Beyer C, Abbas AA, Kamarul T, et al.

Sci Rep, 2017 08 25;7(1):9421.
PMID: 28842627 DOI: 10.1038/s41598-017-09892-w

Pulse electromagnetic fields (PEMFs) have been shown to recruit calcium-signaling cascades common to chondrogenesis. Here we document the effects of specified PEMF parameters over mesenchymal stem cells (MSC) chondrogenic differentiation. MSCs undergoing chondrogenesis are preferentially responsive to an electromagnetic efficacy window defined by field amplitude, duration and frequency of exposure. Contrary to conventional practice of administering prolonged and repetitive exposures to PEMFs, optimal chondrogenic outcome is achieved in response to brief (10 minutes), low intensity (2 mT) exposure to 6 ms bursts of magnetic pulses, at 15 Hz, administered only once at the onset of chondrogenic induction. By contrast, repeated exposures diminished chondrogenic outcome and could be attributed to calcium entry after the initial induction. Transient receptor potential (TRP) channels appear to mediate these aspects of PEMF stimulation, serving as a conduit for extracellular calcium. Preventing calcium entry during the repeated PEMF exposure with the co-administration of EGTA or TRP channel antagonists precluded the inhibition of differentiation. This study highlights the intricacies of calcium homeostasis during early chondrogenesis and the constraints that are placed on PEMF-based therapeutic strategies aimed at promoting MSC chondrogenesis. The demonstrated efficacy of our optimized PEMF regimens has clear clinical implications for future regenerative strategies for cartilage.

Matched MeSH terms: Calcium/metabolism
Antimicrobial activity of gallic acid against thermophilic Campylobacter is strain specific and associated with a loss of calcium ions

Sarjit A, Wang Y, Dykes GA

Food Microbiol, 2015 Apr;46:227-233.
PMID: 25475290 DOI: 10.1016/j.fm.2014.08.002

Gallic acid has been suggested as a potential antimicrobial for the control of Campylobacter but its effectiveness is poorly studied. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of gallic acid against Campylobacter jejuni (n = 8) and Campylobacter coli (n = 4) strains was determined. Gallic acid inhibited the growth of five C. jejuni strains and three C. coli strains (MIC: 15.63-250 μg mL(-1)). Gallic acid was only bactericidal to two C. coli strains (MBC: 125 and 62.5 μg mL(-1)). The mechanism of the bactericidal effect against these two strains (and selected non-susceptible controls) was investigated by determining decimal reduction times and by monitoring the loss of cellular content and calcium ions, and changes in cell morphology. Gallic acid did not result in a loss of cellular content or morphological changes in the susceptible strains as compared to the controls. Gallic acid resulted in a loss of calcium ions (0.58-1.53 μg mL(-1) and 0.54-1.17 μg mL(-1), respectively, over a 180 min period) from the susceptible strains but not the controls. Gallic acid is unlikely to be an effective antimicrobial against Campylobacter in a practical sense unless further interventions to ensure an effective bactericidal mode of action against all strains are developed.

Matched MeSH terms: Calcium/metabolism*
Fulltext Circadian oscillations of cytosolic free calcium regulate the Arabidopsis circadian clock

Martí Ruiz MC, Hubbard KE, Gardner MJ, Jung HJ, Aubry S, Hotta CT, et al.

Nat Plants, 2018 Sep;4(9):690-698.
PMID: 30127410 DOI: 10.1038/s41477-018-0224-8

In the last decade, the view of circadian oscillators has expanded from transcriptional feedback to incorporate post-transcriptional, post-translational, metabolic processes and ionic signalling. In plants and animals, there are circadian oscillations in the concentration of cytosolic free Ca2+ ([Ca2+]cyt), though their purpose has not been fully characterized. We investigated whether circadian oscillations of [Ca2+]cyt regulate the circadian oscillator of Arabidopsis thaliana. We report that in Arabidopsis, [Ca2+]cyt circadian oscillations can regulate circadian clock function through the Ca2+-dependent action of CALMODULIN-LIKE24 (CML24). Genetic analyses demonstrate a linkage between CML24 and the circadian oscillator, through pathways involving the circadian oscillator gene TIMING OF CAB2 EXPRESSION1 (TOC1).

Matched MeSH terms: Calcium/metabolism*
Cellular inhibitory behavior underlying the formation of retinal direction selectivity in the starburst network

Poznanski RR

J Integr Neurosci, 2010 Sep;9(3):299-335.
PMID: 21064220

Optical imaging of dendritic calcium signals provided evidence of starburst amacrine cells exhibiting calcium bias to somatofugal motion. In contrast, it has been impractical to use a dual-patch clamp technique to record membrane potentials from both proximal dendrites and distal varicosities of starburst amacrine cells in order to unequivocally prove that they are directionally sensitive to voltage, as was first suggested almost two decades ago. This paper aims to extend the passive cable model to an active cable model of a starburst amacrine cell that is intrinsically dependent on the electrical properties of starburst amacrine cells, whose various macroscopic currents are described quantitatively. The coupling between voltage and calcium just below the membrane results in a voltage-calcium system of coupled nonlinear Volterra integral equations whose solutions must be integrated into a prescribed model for example, for a synaptic couplet of starburst amacrine cells. Networks of starburst amacrine cells play a fundamental role in the retinal circuitry underlying directional selectivity. It is suggested that the dendritic plexus of starburst amacrine cells provides the substrate for the property of directional selectivity, while directional selectivity is a property of the exclusive layerings and confinement of their interconnections within the sublaminae of the inner plexiform layer involving cone bipolar cells and directionally selective ganglion cells.

Matched MeSH terms: Calcium/metabolism
The effects of Labisia pumila var. alata on bone markers and bone calcium in a rat model of post-menopausal osteoporosis

Shuid AN, Ping LL, Muhammad N, Mohamed N, Soelaiman IN

J Ethnopharmacol, 2011 Jan 27;133(2):538-42.
PMID: 20971181 DOI: 10.1016/j.jep.2010.10.033

AIM OF THE STUDY: Postmenopausal osteoporosis is mainly treated with estrogen replacement therapy (ERT). However, ERT causes side effects, mainly breast cancer, uterine cancer and thromboembolic problems. Labisia pumila var. arata (LPva), a herb with phytoestrogenic effects has the potential to be used as an alternative agent to ERT. This study was conducted to determine the effects of LPva on bone biochemical markers and bone calcium content in ovariectomised rats.
MATERIALS AND METHODS: Thirty two Wistar rats were divided into 4 groups, with 8 rats in each group. The first group was sham operated (Sham), the second group was ovariectomised (OVX), the third (LPva) and fourth group (ERT) were also ovariectomised and given LPva 17.5 mg/kg and Premarin(®) 64.5 μg/kg, respectively. Blood samples were taken before and after treatment to measure osteocalcin and C-terminal telopeptide of type 1 collagen levels using ELISA while the fifth lumbar bone samples were taken to measure bone calcium content using the Atomic Absorption Spectrophotometer (AAS).
RESULTS: The osteocalcin levels were significantly higher in both the LPva and ERT groups compared to the OVX group. The CTX levels were significantly lower in both the LPva and ERT groups compared to the OVX group. However, only the ERT group had significantly higher bone calcium level compared to the OVX group.
CONCLUSION: The supplementation of 17.5 mg/kg of LPva to ovariectomised rats for 8 weeks was able to prevent the changes in bone biochemical markers but failed to prevent the bone calcium loss induced by ovariectomy.

Matched MeSH terms: Calcium/metabolism
Palm vitamin E is comparable to alpha-tocopherol in maintaining bone mineral density in ovariectomised female rats

Norazlina M, Ima-Nirwana S, Gapor MT, Khalid BA

Exp. Clin. Endocrinol. Diabetes, 2000;108(4):305-10.
PMID: 10961363

Vitamin E has been shown to affect bone metabolism. In this study we determined the effects of palm vitamin E and alpha-tocopherol on bone metabolism. Sprague-Dawley female rats fed with normal rat chow were divided into 4 groups and supplemented with either palm vitamin E 30 mg/kg rat weight, palm vitamin E 60 mg/kg rat weight or alpha-tocopherol 30 mg/kg rat weight. One group was not supplemented. Half of these rats were ovariectomised before supplementation was given for 10 months. As expected, bone mineral density of the ovariectomised rats fed on normal rat chow diet was lower compared to the intact rats. However, these changes were not seen in the supplemented group of rats. Both intact and ovariectomised rats supplemented with palm vitamin E 30 mg/kg rat weight had a lower bone calcium content in both femoral and vertebral bones whilst rats fed palm vitamin E 60 mg/kg rat weight or alpha-tocopherol 30 mg/kg rat weight were able to maintain bone calcium content. Alkaline phosphatase activity was elevated in ovariectomised rats supplemented with palm vitamin E 30 mg/kg rat weight and alpha-tocopherol 30 mg/kg rat weight compared to the intact rats. Alpha-tocopherol also reduced the activity of tartrate-resistant acid phosphatase post-ovariectomy. These findings indicate that both palm vitamin E and alpha-tocopherol maintained bone mineral density in ovariectomised rats but caused conflicting effects on bone calcium content. Further study is needed in order to determine the mechanisms involved.

Matched MeSH terms: Calcium/metabolism
Fulltext Expression of protease activated receptor-2 is reduced in renal cell carcinoma biopsies and cell lines

Morais C, Rajandram R, Blakeney JS, Iyer A, Suen JY, Johnson DW, et al.

PLoS One, 2021;16(3):e0248983.
PMID: 33765016 DOI: 10.1371/journal.pone.0248983

Expression of the protease sensing receptor, protease activated receptor-2 (PAR2), is elevated in a variety of cancers and has been promoted as a potential therapeutic target. With the development of potent antagonists for this receptor, we hypothesised that they could be used to treat renal cell carcinoma (RCC). The expression of PAR2 was, therefore, examined in human RCC tissues and selected RCC cell lines. Histologically confirmed cases of RCC, together with paired non-involved kidney tissue, were used to produce a tissue microarray (TMA) and to extract total tissue RNA. Immunohistochemistry and qPCR were then used to assess PAR2 expression. In culture, RCC cell lines versus primary human kidney tubular epithelial cells (HTEC) were used to assess PAR2 expression by qPCR, immunocytochemistry and an intracellular calcium mobilization assay. The TMA revealed an 85% decrease in PAR2 expression in tumour tissue compared with normal kidney tissue. Likewise, qPCR showed a striking reduction in PAR2 mRNA in RCC compared with normal kidney. All RCC cell lines showed lower levels of PAR2 expression than HTEC. In conclusion, we found that PAR2 was reduced in RCC compared with normal kidney and is unlikely to be a target of interest in the treatment of this type of cancer.

Matched MeSH terms: Calcium/metabolism
Vitamin D and Depression: The Evidence from an Indirect Clue to Treatment Strategy

Wong SK, Chin KY, Ima-Nirwana S

Curr Drug Targets, 2018;19(8):888-897.
PMID: 28914205 DOI: 10.2174/1389450118666170913161030

Depression is a common psychiatric disorder that decreases the quality of life and increases the mortality of patients. It incurs significant healthcare costs if left untreated. Even though intervention with antidepressants can reduce depressive symptoms, side effects are often an issue and relapse is very common. Vitamin D, commonly known as the sunshine vitamin, is an essential fat-soluble vitamin for the absorption of calcium to prevent rickets (children) and osteomalacia (adults). Evidence on a possible relationship between vitamin D deficiency and depression is growing. In this review, the authors summarized the evidence on the association between vitamin D status and depression in human observational studies, followed by clinical trials to evaluate the effects of vitamin D supplementation in treating depression. In conclusion, vitamin D deficiency may be associated with an increased risk or severity of depression. Supplementation of vitamin D may confer protection for depressed patients.

Matched MeSH terms: Calcium/metabolism
Fulltext The Role of Calcium in Wound Healing

Subramaniam T, Fauzi MB, Lokanathan Y, Law JX

Int J Mol Sci, 2021 Jun 17;22(12).
PMID: 34204292 DOI: 10.3390/ijms22126486

Skin injury is quite common, and the wound healing is a complex process involving many types of cells, the extracellular matrix, and soluble mediators. Cell differentiation, migration, and proliferation are essential in restoring the integrity of the injured tissue. Despite the advances in science and technology, we have yet to find the ideal dressing that can support the healing of cutaneous wounds effectively, particularly for difficult-to-heal chronic wounds such as diabetic foot ulcers, bed sores, and venous ulcers. Hence, there is a need to identify and incorporate new ideas and methods to design a more effective dressing that not only can expedite wound healing but also can reduce scarring. Calcium has been identified to influence the wound healing process. This review explores the functions and roles of calcium in skin regeneration and reconstruction during would healing. Furthermore, this review also investigates the possibility of incorporating calcium into scaffolds and examines how it modulates cutaneous wound healing. In summary, the preliminary findings are promising. However, some challenges remain to be addressed before calcium can be used for cutaneous wound healing in clinical settings.

Matched MeSH terms: Calcium/metabolism*
Fulltext Bacillus tequilensis strain 'UPMRB9' improves biochemical attributes and nutrient accumulation in different rice varieties under salinity stress

Shultana R, Kee Zuan AT, Yusop MR, Saud HM, El-Shehawi AM

PLoS One, 2021;16(12):e0260869.
PMID: 34898612 DOI: 10.1371/journal.pone.0260869

Soil salinity exert negative impacts on agricultural production and regarded as a crucial issue in global wetland rice production (Oryza sativa L.). Indigenous salt-tolerant plant growth-promoting rhizobacteria (Bacillus sp.) could be used for improving rice productivity under salinity stress. This study screened potential salt-tolerant plant growth-promoting rhizobacteria (PGPR) collected from coastal salt-affected rice cultivation areas under laboratory and glasshouse conditions. Furthermore, the impacts of these PGPRs were tested on biochemical attributes and nutrient contents in various rice varieties under salt stress. The two most promising PGPR strains, i.e., 'UPMRB9' (Bacillus tequilensis 10b) and 'UPMRE6' (Bacillus aryabhattai B8W22) were selected for glasshouse trial. Results indicated that 'UPMRB9' improved osmoprotectant properties, i.e., proline and total soluble sugar (TSS), antioxidant enzymes like superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT). Moreover, 'UPMRB9' inoculated rice plants accumulated higher amount of nitrogen and calcium in tissues. Therefore, the indigenous salt-tolerant PGPR strain 'UPMRB9' could be used as a potential bio-augmentor for improving biochemical attributes and nutrient uptake in rice plants under salinity stress. This study could serve as a preliminary basis for future large-scale trials under glasshouse and field conditions.

Matched MeSH terms: Calcium/metabolism*
Fulltext Genetical and comparative genomics of Brassica under altered Ca supply identifies Arabidopsis Ca-transporter orthologs

Graham NS, Hammond JP, Lysenko A, Mayes S, O Lochlainn S, Blasco B, et al.

Plant Cell, 2014 Jul;26(7):2818-30.
PMID: 25082855 DOI: 10.1105/tpc.114.128603

Although Ca transport in plants is highly complex, the overexpression of vacuolar Ca(2+) transporters in crops is a promising new technology to improve dietary Ca supplies through biofortification. Here, we sought to identify novel targets for increasing plant Ca accumulation using genetical and comparative genomics. Expression quantitative trait locus (eQTL) mapping to 1895 cis- and 8015 trans-loci were identified in shoots of an inbred mapping population of Brassica rapa (IMB211 × R500); 23 cis- and 948 trans-eQTLs responded specifically to altered Ca supply. eQTLs were screened for functional significance using a large database of shoot Ca concentration phenotypes of Arabidopsis thaliana. From 31 Arabidopsis gene identifiers tagged to robust shoot Ca concentration phenotypes, 21 mapped to 27 B. rapa eQTLs, including orthologs of the Ca(2+) transporters At-CAX1 and At-ACA8. Two of three independent missense mutants of BraA.cax1a, isolated previously by targeting induced local lesions in genomes, have allele-specific shoot Ca concentration phenotypes compared with their segregating wild types. BraA.CAX1a is a promising target for altering the Ca composition of Brassica, consistent with prior knowledge from Arabidopsis. We conclude that multiple-environment eQTL analysis of complex crop genomes combined with comparative genomics is a powerful technique for novel gene identification/prioritization.

Matched MeSH terms: Calcium/metabolism*
Fulltext In-VITRo effect of Ficus deltoidea on the contraction of isolated rat's uteri is mediated via multiple receptors binding and is dependent on extracellular calcium

Salleh N, Ahmad VN

BMC Complement Altern Med, 2013;13:359.
PMID: 24330515 DOI: 10.1186/1472-6882-13-359

Ficus deltoidea, is a perennial herb that is used to assist labor, firm the uterus post-delivery and to prevent postpartum bleeding. In view of its claimed uterotonic action, the mechanisms underlying plant's effect on uterine contraction were investigated.

Matched MeSH terms: Calcium/metabolism*
Fulltext A comparative study on morphochemical properties and osteogenic cell differentiation within bone graft and coral graft culture systems

Puvaneswary S, Balaji Raghavendran HR, Ibrahim NS, Murali MR, Merican AM, Kamarul T

Int J Med Sci, 2013;10(12):1608-14.
PMID: 24151432 DOI: 10.7150/ijms.6496

The objective of this study was to compare the morphological and chemical composition of bone graft (BG) and coral graft (CG) as well as their osteogenic differentiation potential using rabbit mesenchymal stem cells (rMSCs) in vitro. SEM analysis of BG and CG revealed that the pores in these grafts were interconnected, and their micro-CT confirmed pore sizes in the range of 107-315 µm and 103-514 µm with a total porosity of 92% and 94%, respectively. EDS analysis indicated that the level of calcium in CG was relatively higher than that in BG. FTIR of BG and CG confirmed the presence of functional groups corresponding to carbonyl, aromatic, alkyl, and alkane groups. XRD results revealed that the phase content of the inorganic layer comprised highly crystalline form of calcium carbonate and carbon. Atomic force microscopy analysis showed CG had better surface roughness compared to BG. In addition, significantly higher levels of osteogenic differentiation markers, namely, alkaline phosphatase (ALP), Osteocalcin (OC) levels, and Osteonectin and Runx2, Integrin gene expression were detected in the CG cultures, when compared with those in the BG cultures. In conclusion, our results demonstrate that the osteogenic differentiation of rMSCs is relatively superior in coral graft than in bone graft culture system.

Matched MeSH terms: Calcium/metabolism
The anti-osteoporotic effect of Eurycoma Longifolia in aged orchidectomised rat model

Shuid AN, Abu Bakar MF, Abdul Shukor TA, Muhammad N, Mohamed N, Soelaiman IN

Aging Male, 2011 Sep;14(3):150-4.
PMID: 20874437 DOI: 10.3109/13685538.2010.511327

Osteoporosis in elderly men is becoming an important health issue with the aging society. Elderly men with androgen deficiency are exposed to osteoporosis and can be treated with testosterone replacement. In this study, Eurycoma longifolia (EL), a plant with androgenic effects, was supplemented to an androgen-deficient osteoporotic aged rat as alternative to testosterone. Aged 12 months old Sprague-Dawley rats were divided into groups of normal control (NC), sham-operated (SO), orchidectomised-control (OrxC), orchidectomised and supplemented with EL (Orx + El) and orchidectomised and given testosterone (Orx + T). After 6 weeks of treatment, serum osteocalcin, serum terminal C-telopeptide Type 1 collagen (CTX) and the fourth lumbar bone calcium were measured. There were no significant differences in the osteocalcin levels before and after treatment in all the groups. The CTX levels were also similar for all the groups before treatment. However, after treatment, orchidectomy had caused significant elevation of CTX compared to normal control rats. Testosterone replacements in orchidectomised rats were able to prevent the rise of CTX. Orchidectomy had also reduced the bone calcium level compared to normal control rats. Both testosterone replacement and EL supplementation to orchidectomised rats were able to maintain the bone calcium level, with the former showing better effects. As a conclusion, EL prevented bone calcium loss in orchidectomised rats and therefore has the potential to be used as an alternative treatment for androgen deficient osteoporosis.

Matched MeSH terms: Calcium/metabolism*
Analytical solution of reaction-diffusion equations for calcium wave propagation in a starburst amacrine cell

Poznanski RR

J Integr Neurosci, 2010 Sep;9(3):283-97.
PMID: 21064219

A reaction-diffusion model is presented to encapsulate calcium-induced calcium release (CICR) as a potential mechanism for somatofugal bias of dendritic calcium movement in starburst amacrine cells. Calcium dynamics involves a simple calcium extrusion (pump) and a buffering mechanism of calcium binding proteins homogeneously distributed over the plasma membrane of the endoplasmic reticulum within starburst amacrine cells. The system of reaction-diffusion equations in the excess buffer (or low calcium concentration) approximation are reformulated as a nonlinear Volterra integral equation which is solved analytically via a regular perturbation series expansion in response to calcium feedback from a continuously and uniformly distributed calcium sources. Calculation of luminal calcium diffusion in the absence of buffering enables a wave to travel at distances of 120 μm from the soma to distal tips of a starburst amacrine cell dendrite in 100 msec, yet in the presence of discretely distributed calcium-binding proteins it is unknown whether the propagating calcium wave-front in the somatofugal direction is further impeded by endogenous buffers. If so, this would indicate CICR to be an unlikely mechanism of retinal direction selectivity in starburst amacrine cells.

Matched MeSH terms: Calcium/metabolism*
Fulltext Vitamin E deficiency reduced lumbar bone calcium content in female rats

Norazlina M, Chua CW, Ima-Nirwana S

Med J Malaysia, 2004 Dec;59(5):623-30.
PMID: 15889565

Vitamin E deficiency has been found to impair bone calcification. This study was done to determine the effects of vitamin E deficiency and supplementation on parathyroid hormone, i.e. the hormone involved in bone regulation. Female Sprague-Dawley rats were divided into 4 groups: 1) normal rat chow (RC), 2) vitamin E deficiency (VED), vitamin E deficient rats supplemented with 3) 60 mg/kg alpha-tocotrienol (ATT) and 4) 60 mg/kg (alpha-tocopherol (ATF). Treatment was carried out for 3 months. Vitamin E deficiency caused hypocalcaemia during the first month of the treatment period, increased the parathyroid hormone level in the second month and decreased the bone calcium content in the 4th lumbar bone at the end of the treatment. Vitamin E supplementation (ATT and ATF) failed to improve these conditions. The bone formation marker, osteocalcin, and the bone resorption marker, deoxypyridinoline did not change throughout the study period. In conclusion vitamin E deficiency impaired bone calcium homeostasis with subsequent secondary hyperparathyroidism and vertebral bone loss. Replacing the vitamin E with pure ATF or pure ATT alone failed to correct the changes seen.

Matched MeSH terms: Calcium/metabolism*
Fulltext Analysis of Comparative Sequence and Genomic Data to Verify Phylogenetic Relationship and Explore a New Subfamily of Bacterial Lipases

Masomian M, Rahman RN, Salleh AB, Basri M

PLoS One, 2016;11(3):e0149851.
PMID: 26934700 DOI: 10.1371/journal.pone.0149851

Thermostable and organic solvent-tolerant enzymes have significant potential in a wide range of synthetic reactions in industry due to their inherent stability at high temperatures and their ability to endure harsh organic solvents. In this study, a novel gene encoding a true lipase was isolated by construction of a genomic DNA library of thermophilic Aneurinibacillus thermoaerophilus strain HZ into Escherichia coli plasmid vector. Sequence analysis revealed that HZ lipase had 62% identity to putative lipase from Bacillus pseudomycoides. The closely characterized lipases to the HZ lipase gene are from thermostable Bacillus and Geobacillus lipases belonging to the subfamily I.5 with ≤ 57% identity. The amino acid sequence analysis of HZ lipase determined a conserved pentapeptide containing the active serine, GHSMG and a Ca(2+)-binding motif, GCYGSD in the enzyme. Protein structure modeling showed that HZ lipase consisted of an α/β hydrolase fold and a lid domain. Protein sequence alignment, conserved regions analysis, clustal distance matrix and amino acid composition illustrated differences between HZ lipase and other thermostable lipases. Phylogenetic analysis revealed that this lipase represented a new subfamily of family I of bacterial true lipases, classified as family I.9. The HZ lipase was expressed under promoter Plac using IPTG and was characterized. The recombinant enzyme showed optimal activity at 65 °C and retained ≥ 97% activity after incubation at 50 °C for 1h. The HZ lipase was stable in various polar and non-polar organic solvents.

Matched MeSH terms: Calcium/metabolism
Effects of tocopherols and tocotrienols on body composition and bone calcium content in adrenalectomized rats replaced with dexamethasone

Ima-Nirwana S, Suhaniza S

J Med Food, 2004;7(1):45-51.
PMID: 15117552

Long-term glucocorticoid treatment is associated with severe side effects, such as obesity and osteoporosis. A palm oil-derived vitamin E mixture had been shown previously to be protective against osteoporosis in rats given 120 microg/kg dexamethasone daily for 12 weeks. In this study we determined the effects of two isomers of vitamin E (i.e., palm oil-derived gamma-tocotrienol and the commercially available alpha-tocopherol, 60 mg/kg of body weight/day) on body composition and bone calcium content in adrenalectomized rats replaced with two doses of dexamethasone, 120 microg/kg and 240 microg/kg daily. Treatment period was 8 weeks. gamma-Tocotrienol (60 mg/kg of body weight/day) was found to reduce body fat mass and increase the fourth lumbar vertebra bone calcium content in these rats, while alpha-tocopherol (60 mg/kg of body weight/day) was ineffective. Therefore, in conclusion, palm oil-derived gamma-tocotrienol has the potential to be utilized as a prophylactic agent in prevention of the side effects of long-term glucocorticoid use.

Matched MeSH terms: Calcium/metabolism

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