MaxiK channel partners: physiological impact

The basic functional unit of the large-conductance, voltage- and Ca²⁺-activated K⁺ (MaxiK, BK, BK_Ca) channel is a tetramer of the pore-forming α-subunit (MaxiKα) encoded by a single gene, Slo , holding multiple alternative exons. Depending on the tissue, MaxiKα can associate with modulatory β-subunits (β1–β4) increasing its functional diversity. As MaxiK senses and regulates membrane voltage and intracellular Ca²⁺, it links cell excitability with cell signalling and metabolism. Thus, MaxiK is a key regulator of vital body functions, like blood flow, uresis, immunity and neurotransmission. Epilepsy with paroxysmal dyskinesia syndrome has been recognized as a MaxiKα-related disorder caused by a gain-of-function C-terminus mutation. This channel region is also emerging as a key recognition module containing sequences for MaxiKα interaction with its surrounding signalling partners, and its targeting to cell-specific microdomains. The growing list of interacting proteins highlights the possibility that associations with the C-terminus of MaxiKα are dynamic and depending on each cellular environment. We speculate that the molecular multiplicity of the C-terminus (and intracellular loops) dictated by alternative exons may modulate or create additional interacting sites in a tissue-specific manner. A challenge is the dissection of MaxiK macromolecular signalling complexes in different tissues and their temporal association/dissociation according to the stimulus.     

Reversible cerebral vasoconstriction syndrome (RCVS): an interesting case report

BackgroundReversible Cerebral Vasoconstriction Syndrome is a condition of transient cerebral vascular spasms, which usually presents with recurrent thunderclap headaches and recovers within 3 months. Several probable triggers and underlying factors, such as sex hormones, vasoactive drugs, head trauma or surgery, and tumors, have been implicated.Case presentationIn this paper, we present a 53-year-old woman with thunderclap headaches and normal lab tests who was radio-clinically diagnosed with reversible cerebral vasoconstriction syndrome and treated accordingly. Then, she experienced the recurrence of RCVS after about 2 years and headaches after 1 year in association with high blood pressure, high blood sugar, hypothyroidism, hyperlipidemia, and a urine metanephrine level of 5 times higher than the normal limit, suggesting a diagnosis of pheochromocytoma. After confirmation of the diagnosis with further imaging studies, surgical removal of the tumor resolved all the signs and symptoms.ConclusionOften underdiagnosed, pheochromocytoma could be an important condition associated with RCVS. It is important for clinicians to bear this diagnosis in mind while dealing with similar cases of recurrent thunderclap headaches.     

Genistein, a soy phytoestrogen, reverses severe pulmonary hypertension and prevents right heart failure in rats

Pretreatment with a phytoestrogen genistein has been shown to attenuate the development of pulmonary hypertension (PH). Because PH is not always diagnosed early, we examined whether genistein could also reverse preexisting established PH and prevent associated right heart failure (RHF). PH was induced in male rats by 60 mg/kg of monocrotaline. After 21 days, when PH was well established, rats received daily injection of genistein (1 mg/kg per day) for 10 days or were left untreated to develop RHF by day 30. Effects of genistein on human pulmonary artery smooth muscle cell and endothelial cell proliferation and neonatal rat ventricular myocyte hypertrophy were assessed in vitro. Severe PH was evident 21 days after monocrotaline, as peak systolic right ventricular pressure increased to 66.35±1.03 mm Hg and right ventricular ejection fraction reduced to 41.99±1.27%. PH progressed to RHF by day 30 (right ventricular pressure, 72.41±1.87 mm Hg; RV ejection fraction, 29.25±0.88%), and mortality was ≈75% in RHF rats. Genistein therapy resulted in significant improvement in lung and heart function as right ventricular pressure was significantly reduced to 43.34±4.08 mm Hg and right ventricular ejection fraction was fully restored to 65.67±1.08% similar to control. Genistein reversed PH-induced pulmonary vascular remodeling in vivo and inhibited human pulmonary artery smooth muscle cell proliferation by ≈50% in vitro likely through estrogen receptor-β. Genistein also reversed right ventricular hypertrophy (right ventricular hypertrophy index, 0.35±0.029 versus 0.70±0.080 in RHF), inhibited neonatal rat ventricular myocyte hypertrophy, and restored PH-induced loss of capillaries in the right ventricle. These improvements in cardiopulmonary function and structure resulted in 100% survival by day 30. Genistein restored PH-induced downregulation of estrogen receptor-β expression in the right ventricle and lung. In conclusion, genistein therapy not only rescues preexisting severe PH but also prevents the progression of severe PH to RHF.     

Biased Homozygous Haplotypes Across the Human Caveolin 1 Upstream Purine Complex in Parkinson’s Disease

The alpha-synuclein–caveolin 1 axis is suggested to be of role in the pathogenesis of Parkinson’s disease in cell line models. The objective of this study was to analyze the homozygous haplotype compartment of the human caveolin 1 gene upstream purine complex in patients afflicted with Parkinson’s disease. This complex was screened in patients with Parkinson’s disease (n?=?141) and compared with a group of controls (n?=?760) using polymerase chain reaction and sequencing. The expression activity of the homozygous haplotypes was then examined using luciferase Dual-Glo system in human neuronal cell line, LAN-5. Six haplotypes were found to be homozygous in the patients, and not in the control pool (Fisher exact p?<?1?×?10^?6). Three of those haplotypes were specific to Parkinson’s disease (Fisher exact p?<?0.002), and the remaining three overlapped with homozygous haplotypes in Alzheimer’s disease and multiple sclerosis (Fisher exact p?<?0.002). The disease haplotypes contained motif lengths that were nonexistent in the control homozygous haplotype pool and significantly increased gene expression (p?<?9?×?10^—6). We conclude that skew in the caveolin 1 purine complex homozygous haplotype compartment and an additive effect of those haplotypes may be linked with Parkinson’s disease.     

Three-Dimensional Printing of Cell Exclusion Spacers (CES) for Use in Motility Assays

Purpose

Cell migration/invasion assays are widely used in commercial drug discovery screening. 3D printing enables the creation of diverse geometric restrictive barrier designs for use in cell motility studies, permitting on-demand assays. Here, the utility of 3D printed cell exclusion spacers (CES) was validated as a cell motility assay.

Methods

A novel CES fit was fabricated using 3D printing and customized to the size and contour of 12 cell culture plates including 6 well plates of basal human brain vascular endothelial (D3) cell migration cells compared with 6 well plates with D3 cells challenged with 1uM cytochalasin D (Cyto-D), an F-actin anti-motility drug. Control and Cyto-D treated cells were monitored over 3 days under optical microscopy.

Results

Day 3 cell migration distance for untreated D3 cells was 1515.943μm?±?10.346μm compared to 356.909μm?±?38.562μm for the Cyt-D treated D3 cells (p?<?0.0001). By day 3, untreated D3 cells reached confluency and completely filled the original voided spacer regions, while the Cyt-D treated D3 cells remained significantly less motile.

Conclusions

Cell migration distances were significantly reduced by Cyto-D, supporting the use of 3D printing for cell exclusion assays. 3D printed CES have great potential for studying cell motility, migration/invasion, and complex multi-cell interactions.

     

Association of toxicochemical and microbiological quality of bottled mineral water in Birjand city,Iran

Water is one of the pivotal, both in natural ecosystems and human development. Inadequate and unsafe water is still one of the major challenges in most developing countries. Due to the growing trends of bottled water (BW) consumption in Iran, especially in dry regions, regular monitoring of the quality of bottled mineral water is necessary. Therefore, this cross-sectional study was carried out to evaluate the chemical and microbiological quality of bottled mineral water which was sold in the markets of Birjand city, Iran in 2015. Samples were selected randomly from 12 most popular brands of national BW in autumn and winter. Then, 12 most popular brands were selected for analysis. Finally, parameters including total hardness, levels of calcium, magnesium, pH, bicarbonate, sulfate, alkalinity, residual chlorine and total and fecal coliforms were examined for each brand. The results of the present study revealed that most of the chemical and microbiological parameters of BW in Birjand city were lower than maximum contaminant levels which are set by Iranian mineral water quality standards and WHO guidelines. Furthermore, total and fecal coliforms were within the standards. Overall, the results of this study revealed that the health status of the bottled mineral water which is sold in the markets of Birjand city was good. But, regular monitoring of the above mentioned parameters would be helpful to improve the water quality and to provide good portable water for the dwellers and very effective to enhance public health on citizens.