Metabolic Alkalosis

Metabolic alkalosis is a disorder where the primary defect, an increase in plasma bicarbonate concentration, leads to an increase in systemic pH. Here we review the causes of metabolic alkalosis with an emphasis on the inherited causes, namely Gitelman syndrome and Bartter syndrome and syndromes which mimic them. We detail the importance of understanding the kidney pathophysiology and molecular genetics in order to distinguish these syndromes from acquired causes. In particular we discuss the tubular transport of salt in the thick ascending limb of the loop of Henle, the distal convoluted tubule and the collecting duct. The effects of salt wasting, namely an increase in the renin-angiotensin-aldosterone axis are discussed in order to explain the biochemical phenotypes and targeted treatment approaches to these conditions

Cystinuria: A Review of Inheritance Patterns, Diagnosis, Medical Treatment and Prevention of Stones

Cystinuria is a rare inherited renal stone disease. Mutations in two genes SLC3A1 and SLC7A9 underlie this condition, encoding proteins that facilitate dibasic amino acid exchange which are expressed in the gut and the proximal tubule of the kidney. Genetic studies now allow precise genotyping of patients who may have both autosomal dominant and autosomal recessive patterns of disease. The disorder is characterised by the urinary loss of cystine, lysine, ornithine, and arginine, and the insolubility of cystine gives rise to crystalluria and cysteine-containing renal stones. Although an inherited condition, it may present at any age. Clinical management combines lifestyle advice and preventative medical therapy. However, many patients require surgical interventions to remove problematic stones from the urinary tract. Preventative therapies include increased fluid intake, alkalinization of the urine, and the use of cystine-binding drugs, including penicillamine and tiopronin, which form soluble heterodimers with cystine

Clinical and Biochemical Features of Patients with CYP24A1 Mutations

The CYP24A1 gene encodes 1,25-hydroxyvitamin-D3-24-hydroxylase, a key enzyme responsible for the catabolism of active vitamin D (1,25-dihydroxyvitamin D3). Loss-of-function mutations in CYP24A1 lead to increased levels of active vitamin D metabolites. Clinically, two distinct phenotypes have been recognised from this: infants with CYP24A1 mutations present with infantile idiopathic hypercalcaemia, often precipitated by prophylactic vitamin D supplementation. A separate phenotype of nephrolithiasis, hypercalciuria and nephrocalcinosis often presents in adulthood. CYP24A1 mutations should be suspected when a classical biochemical profile of high active vitamin D metabolites, high or normal serum calcium, high urine calcium and low parathyroid hormone is detected. Successful treatment with fluconazole, a P450 enzyme inhibitor, has been shown to be effective in individuals with CYP24A1 mutations. Although CYP24A1 mutations are rare, early recognition can prompt definitive diagnosis and ensure treatment is commenced

Role of Genetic Testing in Kidney Stone Disease: A Narrative Review

Purpose of Review: Kidney stone disease (KSD) is a common and potentially life-threatening condition, and half of patients experience a repeat kidney stone episode within 5–10 years. Despite the ~50% estimate heritability of KSD, international guidelines have not kept up with the pace of discovery of genetic causes of KSD. The European Association of Urology guidelines lists 7 genetic causes of KSD as ‘high risk’. Recent Findings: There are currently 46 known monogenic (single gene) causes of kidney stone disease, with evidence of association in a further 23 genes. There is also evidence for polygenic risk of developing KSD. Evidence is lacking for recurrent disease, and only one genome wide association study has investigated this phenomenon, identifying two associated genes (SLC34A1 and TRPV5). However, in the absence of other evidence, patients with genetic predisposition to KSD should be treated as ‘high risk’. Further studies are needed to characterize both monogenic and polygenic associations with recurrent disease, to allow for appropriate risk stratification. Durability of test result must be balanced against cost. This would enable retrospective analysis if no genetic cause was found initially. Summary: We recommend genetic testing using a gene panel for all children, adults < 25 years, and older patients who have factors associated with high risk disease within the context of a wider metabolic evaluation. Those with a genetic predisposition should be managed via a multi-disciplinary team approach including urologists, radiologists, nephrologists, clinical geneticists and chemical pathologists. This will enable appropriate follow-up, counselling and potentially prophylaxis

Reviews

The following publications have been reviewed by the mentioned authors;Beginning Graphical Communication by M. Jordan, B. Hawtin and A. Neil, reviewed by John LeesArt Related Topics by Bob Nunn and Chris Locke, reviewed by A. CharltonHandbook for Art and Design Students by Robin Jesson, reviewed by John LancasterDrawing and Cognition Descriptive and Experimental Studies of Graphic Production Processes by Peter Van Sommers, reviewed by Pamela M. SchenkThe Student's Guide to Western Calligraphy an Illustrated Survey by Joyce Irene Whalley, reviewed by John LancasterSource Directory for Authentic Indian, Eskimo and Aleut Arts and Crafts by the Indian Arts and Crafts BoardMarianne Straub by Mary Schoeser, reviewed by Kim GreerMisha Black by Avril Blake, reviewed by Kim Greer'Working in Crafts' - A National Survey by the Crafts Council, reviewed by L. SayerDirectory of Design Expertise by the Design Council, reviewed by R. Smit

Jouberin localizes to collecting ducts and interacts with nephrocystin-1

Joubert syndrome and related disorders are autosomal recessive multisystem diseases characterized by cerebellar vermis aplasia/hypoplasia, retinal degeneration and cystic kidney disease. There are five known genes; mutations of which give rise to a spectrum of renal cystic diseases the most common of which is nephronophthisis, a disorder characterized by early loss of urinary concentrating ability, renal fibrosis, corticomedullary cyst formation and renal failure. Many of the proteins encoded by these genes interact with one another and are located at adherens junctions or the primary cilia and or basal bodies. Here we characterize Jouberin, a multi-domain protein encoded by the AHI1 gene. Immunohistochemistry with a novel antibody showed that endogenous Jouberin is expressed in brain, kidney and HEK293 cells. In the kidney, Jouberin co-localized with aquaporin-2 in the collecting ducts. We show that Jouberin interacts with nephrocystin-1 as determined by yeast-2-hybrid system and this was confirmed by exogenous and endogenous co-immunoprecipitation in HEK293 cells. Jouberin is expressed at cell-cell junctions, primary cilia and basal body of mIMCD3 cells while a Jouberin-GFP construct localized to centrosomes in subconfluent and dividing MDCK cells. Our results suggest that Jouberin is a protein whose expression pattern supports both the adherens junction and the ciliary hypotheses for abnormalities leading to nephronophthisis

Opportunity or dead end? Rethinking the study of entrepreneurial action without a concept of opportunity

This article has two objectives: to critique the dominant opportunity discovery and creation literatures and to propose a new, critical realist–inspired analytical framework to theorise the causes, processes and consequences of entrepreneurial action – one that needs no concept of opportunity. We offer three reasons to support our critique of opportunity studies. First, there are important absences, contradictions and inconsistencies in definitions of opportunity in theoretical and empirical work that mean the term cannot signal a clear direction for theorising or empirical research. Our central criticism is that the concept of opportunity cannot refer simultaneously, without contradiction, to a social context offering profit-making prospects, to particular practices and to agents’ subjective beliefs or imagined futures. Second, a new definition of opportunity would perpetuate the conceptual chaos. Third, useful concepts to capture important entrepreneurial processes are readily available, for instance, combining resources, creating new ventures and achieving product sales, which render a concept of opportunity superfluous. Instead, we conceptualise entrepreneurial action as investments in resources intended to create new goods and services for market exchange emergent from the interaction between agential, socialstructural and cultural causal powers

The IL-33:ST2 axis is unlikely to play a central fibrogenic role in idiopathic pulmonary fibrosis

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) is a devastating interstitial lung disease (ILD) with limited treatment options. Interleukin-33 (IL-33) is proposed to play a role in the development of IPF however the exclusive use of prophylactic dosing regimens means that the therapeutic benefit of targeting this cytokine in IPF is unclear. METHODS: IL-33 expression was assessed in ILD lung sections and human lung fibroblasts (HLFs) by immunohistochemistry and gene/protein expression and responses of HLFs to IL-33 stimulation measured by qPCR. In vivo, the fibrotic potential of IL-33:ST2 signalling was assessed using a murine model of bleomycin (BLM)-induced pulmonary fibrosis and therapeutic dosing with an ST2-Fc fusion protein. Lung and bronchoalveolar lavage fluid were collected for measurement of inflammatory and fibrotic endpoints. Human precision-cut lung slices (PCLS) were stimulated with transforming growth factor-β (TGFβ) or IL-33 and fibrotic readouts assessed. RESULTS: IL-33 was expressed by fibrotic fibroblasts in situ and was increased by TGFβ treatment in vitro. IL-33 treatment of HLFs did not induce IL6, CXCL8, ACTA2 and COL1A1 mRNA expression with these cells found to lack the IL-33 receptor ST2. Similarly, IL-33 stimulation had no effect on ACTA2, COL1A1, FN1 and fibronectin expression by PCLS. Despite having effects on inflammation suggestive of target engagement, therapeutic dosing with the ST2-Fc fusion protein failed to reduce BLM-induced fibrosis measured by hydroxyproline content or Ashcroft score. CONCLUSIONS: Together these findings suggest the IL-33:ST2 axis does not play a central fibrogenic role in the lungs with therapeutic blockade of this pathway unlikely to surpass the current standard of care for IPF

ARL3 mutations cause Joubert syndrome by disrupting ciliary protein composition

Joubert syndrome (JBTS) is a genetically heterogeneous autosomal recessive neurodevelopmental ciliopathy. We investigated further the underlying genetic etiology of Joubert syndrome by studying two unrelated families in whom JBTS was not associated with pathogenic variants in known JBTSrelated genes. Combined autozygosity mapping of both families highlighted a candidate locus on chromosome 10 (chr10: 101569997-109106128 (hg 19)), and exome sequencing revealed two missense variants in ARL3 within the candidate locus. The encoded protein, ADP Ribosylation Factor-Like GTPase 3, ARL3, is a small GTP-binding protein that is involved in directing lipid-modified proteins into the cilium in a GTP-dependent manner. Both missense variants replace the highly conserved Arg149 residue, which we show to be necessary for the interaction with its guanine nucleotide exchange factor ARL13B, such that the mutant protein is associated with reduced INPP5E and NPHP3 localisation in cilia. We propose that ARL3 provides a potential hub in the network of encoded ciliopathy genes, whereby perturbation of ARL3 results in the mislocalisation of multiple ciliary proteins due to abnormal displacement of lipidated protein cargo