Calcium Accumulation and Loss and Vitamin D3 Content of Feeder Black Field Crickets (Gryllus bimaculatus) Fed on a High Calcium Diet with and without UVB Irradiation

Calcium metabolism in insectivores may be perturbed by insufficient calcium or vitamin D3. Insects may be gut loaded to increase calcium content, and recent research shows that exposure to UVB radiation can increase the vitamin D3 content of some invertebrates. Typical gut loading protocols result in peak calcium content after 24–48 h, while existing evidence with UVB irradiation involves exposure periods of tens of days. We UVB-irradiated fasted black field crickets (Gryllus bimaculatus) while feeding them on high calcium diets for 48 h, then fasted them for a further 24 h, and measured the vitamin D3, calcium, and phosphorus content compared with non-irradiated controls. UVB irradiation had no effect on vitamin D3 (crickets had no detectable levels of vitamin D3 at any point), or on calcium accumulation rates, which approximated existing research. Crickets significantly increased their calcium:phosphorus ratio from 0.17 to approximately 0.4 over 24 h and this did not increase over a further 24 h of feeding. Removal of the food source resulted in loss of all accumulated calcium within 24 h. Our results have implications for managing food sources for captive insectivores and highlight the importance of good feeder preparation and rapid consumption to ensure optimal calcium delivery to predators.

Role of Calcium Homeostasis in Ischemic Stroke: A Review

: Stroke is the second most common cause of death worldwide. It occurs due to the insufficient supply of oxygen-rich blood to the brain. It is a complex disease with multiple associated risk factors including smoking, alcoholism, age, sex, ethnicity, etc. Calcium ions are known to play a vital role in cell death pathways, which is a ubiquitous intracellular messenger during and immediately after an ischemic period. Disruption in normal calcium hemostasis is known to be a major initiator and activator of the ischemic cell death pathway. Under Ischemic stroke conditions, glutamate is released from the neurons and glia which further activates the N-methyl-D-aspartate (NMDA) receptor and triggers the rapid translocation of Ca2+ from extracellular to intracellular spaces in cerebral tissues and vice versa. Various studies indicated that Ca2+ could have harmful effects on neurons under acute ischemic conditions. Mitochondrial dysfunction also contributes to delayed neuronal death, and it was established decades ago that massive calcium accumulation triggers mitochondrial damage. Elevated Ca2+ levels cause mitochondria to swell and release their contents. As a result oxidative stress and mitochondrial calcium accumulation activate mitochondrial permeability transition and lead to depolarization-coupled production of reactive oxygen species. This association between calcium levels and mitochondrial death suggests that elevated calcium levels might have a role in the neurological outcome in ischemic stroke. Previous studies have also reported that elevated Ca2+ levels play a role in the determination of infarct size, outcome, and recurrence of ischemic stroke. The current review has been compiled to understand the multidimensional role of altered Ca2+ levels in the initiation and alteration of neuronal death after ischemic attack. The underlying mechanisms understood to date have also been discussed.

Lactoferrin-Anchored Tannylated Mesoporous Silica Nanomaterials for Enhanced Osteo-Differentiation Ability

In the present study, we created lactoferrin-anchored mesoporous silica nanomaterials with absorbed tannic acid (LF/TA-MSNs) and evaluated the effect of these LF/TA-MSNs on the in vitro osteo-differentiation ability of adipose-derived stem cells (ADSCs) by testing alkaline phosphatase (ALP) level, calcium accumulation, and expression of osteo-differentiation-specific genes, including osteocalcin (OCN) and osteopontin (OPN). Both bare MSNs and LF/TA-MSNs exhibited round nano-particle structures. The LF/TA-MSNs demonstrated prolonged LF release for up to 28 days. Treatment of ADSCs with LF (50 μg)/TA-MSNs resulted in markedly higher ALP level and calcium accumulation compared to treatment with LF (10 μg)/TA-MSNs or bare MSNs. Furthermore, LF (50 μg)/TA-MSNs remarkably increased mRNA levels of osteo-differentiation-specific genes, including OCN and OPN, compared to MSNs or LF (10 μg)/TA-MSNs. Together, these data suggest that the ability of LF/TA-MSNs to enhance osteo-differentiation of ADSCs make them a possible nanovehicle for bone healing and bone regeneration in patients with bone defect or disease.

A Novel Ex Vivo Model of Aortic Valve Calcification. A Preliminary Report

Background: No pharmacological treatment exists to prevent or stop the calcification process of aortic valves causing aortic stenosis. The aim of this study was to develop a robust model of induced calcification in whole aortic valve leaflets which could be suitable for studies of the basic mechanisms and for testing potentially inhibitory drugs.Methods: Pig hearts were obtained from a commercial abattoir. The aortic valve leaflets were dissected free and randomized between experimental groups. Whole leaflets were cultured in individual wells. Two growth media were used for cultivation: standard growth medium and an antimyofibroblastic growth medium. The latter was employed to inhibit contraction of the leaflet into a ball-like structure. Calcification was induced in the growth medium by supplementation with an osteogenic medium. Leaflets were cultivated for four weeks and medium was changed every third day. To block calcification, the inhibitor SNF472 (a formulation of the hexasodium salt of myo-inositol hexaphosphate hexasodium salt) was used at concentrations between 1 and 100 µM. After cultivation for four weeks the leaflets were snap frozen in liquid nitrogen and kept at −80 °C until blind assessment of the calcium amount in leaflets by inductively coupled plasma optical emission spectroscopy. For statistical analysis, a Kruskal–Wallis test with Dunn’s post-test was applied.Results: Osteodifferentiation with calcium accumulation was in principle absent when standard medium was used. However, when the antimyofibroblastic medium was used, a strong calcium accumulation was induced (p = 0.006 compared to controls), and this was blocked in a dose-dependent manner by the calcification inhibitor SNF472 (p = 0.008), with an EC50 of 3.3 µM.Conclusion: A model of experimentally induced calcification in cultured whole leaflets from porcine aortic valves was developed. This model can be useful for studying the basic mechanisms of valve calcification and to test pharmacological approaches to inhibit calcification.

Excessive Calcium Accumulation in the Roots Is a Key Factor in Tipburn Incidence under High Ca Supply in Lisianthus (Eustoma grandiflorum) Cultivars

In lisianthus cultivars, the occurrence of tipburn is known to adversely affect quality and yield. However, information concerning the responses of tipburn incidence to different levels of Ca is limited. In addition, only a few studies have investigated the effect of potassium (K) concentration on Ca acquisition and distribution in lisianthus. To address this knowledge gap, we investigated tipburn incidence in three lisianthus cultivars (Umi honoka (UH), Reina white (RW), and Voyage peach (VP)) and the Ca and K concentrations in them under different concentrations of Ca supply (40, 80, and 120 ppm). These cultivars exhibited different responses to different concentrations of Ca supply. Tipburn was not observed in UH. In RW, tipburn incidence and severity significantly decreased with an increase in nutritional Ca concentration, because the Ca concentration in the tips of the top leaves significantly increased with Ca concentration. By contrast, in VP, tipburn incidence under all treatments was 100%, and there was no significant difference in the Ca concentration in the tips of the top leaves among the treatments, but the total Ca concentration significantly increased. VP was the only cultivar that significantly acquired and accumulated more Ca in the roots with an increase in nutritional Ca concentration. Overall, excessive Ca accumulation in the roots under high-Ca conditions inhibits the distribution of Ca to the tips of the top leaves and eventually manifests as tipburn in the cultivar. In addition, our results suggested that the content ratio of K in the nutrient solutions did not prevent Ca acquisition and distribution in lisianthus cultivars and that the K concentration has a negligible effect on the occurrence of tipburn.