Hearing Impairment and Severe Attention Deficit/Hyperactivity Disorder: A Nationwide Study.

BACKGROUND: The association between hearing impairment and attention-deficit/hyperactivity disorder (ADHD) is unclear. Therefore, we aimed to assess this association in Israel's national sample of over 1.1 million adolescents. METHODS: We conducted a nationwide, population-based, cross-sectional study of all Israeli adolescents (n = 1,175,534, 58% males; mean age, 17 yrs) who were examined before mandatory military service during 2004 to 2020. Board-certified specialists confirmed diagnoses of hearing impairment and severe ADHD. MAIN OUTCOMES AND MEASURES: We compared the prevalence of severe ADHD in adolescents with and without hearing impairment. Associations were analyzed using logistic regression models and sensitivity analyses accounting for hearing impairment type (sensorineural vs. conductive) and severity. RESULTS: Of the 8,769 adolescents with hearing impairment, 57 were diagnosed with severe ADHD (prevalence = 0.65%). Of the 1,166,765 adolescents without hearing impairment, 3,936 were diagnosed with severe ADHD (prevalence = 0.29%). We found a significant association between hearing impairment and severe ADHD (odds ratio = 1.93 [95% confidence interval, 1.47-2.49]), which persisted in a multivariable model adjusted to age, sex, socioeconomic status, educational status, cognitive performance, and immigration status (odds ratio = 1.70 [95% confidence interval, 1.29-2.20]). The association also persisted when stratified by hearing impairment type (sensorineural vs. conductive) and severity. CONCLUSIONS: Adolescents with hearing impairment had 70% increased odds of severe ADHD. Study findings suggest that active screening of patients with hearing impairment for ADHD should be considered.

miR-128 as a Regulator of Synaptic Properties in 5xFAD Mice Hippocampal Neurons.

Alzheimer's disease (AD) is characterized by progressive synaptic dysfunction, deterioration of neuronal transmission, and consequently neuronal death. Although there is no treatment for AD, exposure to enriched environment (EE) in mice, as well as physical and mental activity in human subjects have been shown to have a protective effect by slowing the disease's progression and reducing AD-like cognitive impairment. However, the molecular mechanism of this mitigating effect is still not understood. One of the mechanisms that has recently been shown to be involved in neuronal degeneration is microRNAs (miRNAs) regulation, which act as a post-transcriptional regulators of gene expression. miR-128 has been shown to be significantly altered in individuals with AD and in mice following exposure to EE. Here, we focused on elucidating the possible role of miR-128 in AD pathology and found that miR-128 regulates the expression of two proteins essential for synaptic transmission, SNAP-25, and synaptotagmin1 (Syt1). Clinically relevant, in 5xFAD mouse model for AD, this miRNA's expression was found as downregulated, resembling the alteration found in the hippocampi of individuals with AD. Interestingly, exposing WT mice to EE also resulted in downregulation of miR-128 expression levels, although EE and AD conditions demonstrate opposing effects on neuronal functioning and synaptic plasticity. We also found that miR-128 expression downregulation in primary hippocampal cultures from 5xFAD mice results in increased neuronal network activity and neuronal excitability. Altogether, our findings place miR-128 as a synaptic player that may contribute to synaptic functioning and plasticity through regulation of synaptic protein expression and function.

Pendrin, a novel transcriptional target of the uroguanylin system.

Guanylin (GN) and uroguanylin (UGN) are low-molecular-weight peptide hormones produced mainly in the intestinal mucosa in response to oral salt load. GN and UGN (guanylin peptides) induce secretion of electrolytes and water in both intestine and kidney. Thought to act as "intestinal natriuretic factors", GN and UGN modulate renal salt secretion by both endocrine mechanisms (linking the digestive system and kidney) and paracrine/autocrine (intrarenal) mechanisms. The cellular function of GN and UGN in intestine and proximal tubule is mediated by guanylyl cyclase C (GC-C)-, cGMP-, and G protein-dependent pathways, whereas, in principal cells of the cortical collecting duct (CCD), these peptide hormones act via GC-C-independent signaling through phospholipase A2 (PLA2). The Cl(-)/HCO(-)3 exchanger pendrin (SLC26A4), encoded by the PDS gene, is expressed in non-α intercalated cells of the CCD. Pendrin is essential for CCD bicarbonate secretion and is also involved in NaCl balance and blood pressure regulation. Our recent studies have provided evidence that pendrin-mediated anion exchange in the CCD is regulated at the transcriptional level by UGN. UGN exerts an inhibitory effect on the pendrin gene promoter likely via heat shock factor 1 (HSF1) action at a defined heat shock element (HSE) site. Recent studies have unraveled novel roles for guanylin peptides in several organ systems including involvement in appetite regulation, olfactory function, cell proliferation and differentiation, inflammation, and reproductive function. Both the guanylin system and pendrin have also been implicated in airway function. Future molecular research into the receptors and signal transduction pathways involved in the action of guanylin peptides and the pendrin anion exchanger in the kidney and other organs, and into the links between them, may facilitate discovery of new therapies for hypertension, heart failure, hepatic failure and other fluid retention syndromes, as well as for diverse diseases such as obesity, asthma, and cancer.

The pendrin anion exchanger gene is transcriptionally regulated by uroguanylin: a novel enterorenal link.

The pendrin/SLC26A4 Cl(-)/HCO(3)(-) exchanger, encoded by the PDS gene, is expressed in cortical collecting duct (CCD) non-A intercalated cells. Pendrin is essential for CCD bicarbonate secretion and is also involved in NaCl balance and blood pressure regulation. The intestinal peptide uroguanylin (UGN) is produced in response to oral salt load and can function as an "intestinal natriuretic hormone." We aimed to investigate whether UGN modulates pendrin activity and to explore the molecular mechanisms responsible for this modulation. Injection of UGN into mice resulted in decreased pendrin mRNA and protein expression in the kidney. UGN decreased endogenous pendrin mRNA levels in HEK293 cells. A 4.2-kb human PDS (hPDS) promoter sequence and consecutive 5' deletion products were cloned into luciferase reporter vectors and transiently transfected into HEK293 cells. Exposure of transfected cells to UGN decreased hPDS promoter activity. This UGN-induced effect on the hPDS promoter occurred within a 52-bp region encompassing a single heat shock element (HSE). The effect of UGN on the promoter was abolished when the HSE located between nt -1119 and -1115 was absent or was mutated. Furthermore, treatment of HEK293 cells with heat shock factor 1 (HSF1) small interfering RNA (siRNA) reversed the UGN-induced decrease in endogenous PDS mRNA level. In conclusion, pendrin-mediated Cl(-)/HCO(3)(-) exchange in the renal tubule may be regulated transcriptionally by the peptide hormone UGN. UGN exerts its inhibitory activity on the hPDS promoter likely via HSF1 action at a defined HSE site. These data define a novel signaling pathway involved in the enterorenal axis controlling electrolyte and water homeostasis.

Transcriptional regulation of the pendrin gene.

Pendrin (SLC26A4), a Cl(-)/anion exchanger encoded by the gene PDS, is highly expressed in the kidney, thyroid and inner ear epithelia and is essential for bicarbonate secretion/chloride reabsorption, iodide accumulation and endolymph ion balance, respectively. The molecular mechanisms controlling pendrin activity in renal, thyroid and inner ear epithelia have been the subject of recent studies. The effects of ambient pH, the hormone aldosterone and the peptide uroguanylin (UGN; the "intestinal natriuretic hormone"), known modulators of electrolyte balance, on transcription of the pendrin gene, have been investigated. Luciferase reporter plasmids containing different length fragments of the human PDS (hPDS) promoter were transfected into renal HEK293, thyroid LA2, and inner ear VOT36 epithelial cells. Acidic pH decreased and alkaline pH increased hPDS promoter activity in transfected HEK293 and VOT36, but not in LA2 cells. Aldosterone reduced hPDS promoter activity in HEK293 but had no effect in LA2 and VOT36 cells. These pH and aldosterone-induced effects on the hPDS promoter occurred within 96-bp and 89-bp regions, respectively, which likely contain distinct response elements to these modulators. Injection of UGN into mice resulted in decreased pendrin mRNA and protein expression in the kidney. Exposure of transfected HEK293 to UGN decreased hPDS promoter activity. The findings provided evidence for the presence of a UGN response element within the 96-bp region overlapping with the pH response element on the hPDS promoter. Pendrin is also expressed in airway epithelium. The cytokins interleukin 4 (IL-4) and interleukin-13 (IL-13), known regulators of airway surface function, have been shown to increase hPDS promoter activity by a STAT6-dependent mechanism. In conclusion, systemic pH, the hormone aldosterone, and the peptide UGN influence renal tubular pendrin gene expression and, perhaps, pendrin-mediated Cl(-)/HCO(3)(-) exchange at the transcriptional level. Pendrin-driven anion transport in the endolymph and at the airway surface may be regulated transcriptionally by systemic pH and IL-3/IL-4, respectively. The distinct response elements and the corresponding transcription factors mediating the effect of these modulators on the PDS promoter remain to be identified and characterized.

Non-Jewish Israeli IBD patients have significantly higher glutathione S-transferase GSTT1-null frequency.

BACKGROUND: The involvement of oxidant/antioxidant imbalance in the development of inflammatory bowel disease (IBD) is well documented. Two members of the glutathione S-transferase (GST) family of enzymes, GSTM1 and GSTT1, known to take part in cellular protection against electrophiles, demonstrate common deletion variants (termed null) associated with impaired enzyme function. AIM: To evaluate the effect of GSTM1/GSTT1 genotype on IBD susceptibility in a Israeli cohort and to study the correlation between GSTM1/GSTT1 genotype, smoking status, and a variety of clinical characteristics of IBD. METHODS: A cohort of 606 Israeli IBD patients (453 with Crohn's disease [CD] and 153 with ulcerative colitis [UC]) and 528 ethnically matched healthy controls were genotyped for the null variants of GSTM1 and GSTT1. In patients, phenotype-genotype correlations were examined. RESULTS: Ethnic stratification of healthy controls revealed a higher frequency of GSTT1-null in Jewish and Arab Moslem individuals compared to Druze individuals (P < 0.0005), but no difference in GSTM1-null was found. Comparing IBD patients (both CD and UC) to healthy controls revealed a pattern of lower GSTM1-null and higher GSTT1-null frequencies, which reached significance in Arab Moslem patients. No association was found between NOD2/CARD15 mutation carriage and GSTM1/GSTT1 genotype. No statistically significant association was found between GSTT1-null or GSTM1-null, smoking status, and other phenotypes of CD/UC. CONCLUSIONS: GSTT1-null appears to be associated with IBD, while GSTM1-null appears to be conversely associated with IBD. No association was found between GSTT1-null or GSTM1-null and specific IBD phenotypes.

Influence of glutathione S-transferase A1, P1, M1, T1 polymorphisms on oral busulfan pharmacokinetics in children with congenital hemoglobinopathies undergoing hematopoietic stem cell transplantation.

BACKGROUND: Busulfan (BU), often used in high dose for myeloablation before hematopoietic stem cell transplantation (HSCT), has been implicated in certain HSCT toxicities, including the occurrence of hepatic veno-occlusive disease (HVOD). In addition to weight and age, gene polymorphisms in specific members of the glutathione-transferase (GST) gene family (A1, P1, M1, and T1), involved in BU metabolism, may play a role in the wide inter-patient variability in systemic BU concentrations. PROCEDURE: The present study integrated clinical data regarding the occurrence of HVOD, graft versus host disease (GVHD), BU pharmacokinetics and GSTA1, GSTP1, GSTM1, and GSTT1 genotypes of 18 children who received BU in their pre-HSCT conditioning regimen. The children were all treated for congenital hemoglobinopathies and were all of Arab Moslem descent. RESULTS: The data demonstrate an association between GSTA1 and GSTP1 genotypes and BU-maximal concentration (C(max)) (P = 0.01, P = 0.02, respectively), area under the concentration-time curve (AUC) (P = 0.02, P = 0.01, respectively) and oral BU clearance/kg body weight (P < 0.02, P = 0.08, respectively). GSTM1-null individuals demonstrated lower BU-AUC/Kg compared to GSTM1-positive individuals. In addition, an association between GVHD and GSTM1-null genotype was found. CONCLUSIONS: GSTA1, GSTP1, and GSTM1 genotyping prior to HSCT in children with congenital hemoglobinopathies may allow better prediction of oral BU kinetics and the need for BU dose adjustment, as well as prediction of transplant related toxicity such as GVHD, thereby improving clinical outcome.

Distribution of TPMT risk alleles for thiopurine [correction of thioupurine] toxicity in the Israeli population.

BACKGROUND AND OBJECTIVE: Individuals with intermediate or no thiopurine S-methyltransferase (TPMT) activity are at risk of hematotoxicity when treated with standard doses of thiopurines, thus, pretreatment identification of these individuals is of major importance. The purpose of this study was to determine the frequency and distribution of TPMT polymorphic variants, known to functionally impair TPMT activity, in the highly heterogeneous Israeli population. METHODS: TPMT genotyping of individuals representing three major demographic groups in Israel was carried out by PCR restriction fragment length polymorphism and high-resolution melting. RESULTS: Frequencies of TPMT risk alleles differed significantly among the screened Israeli subpopulations: Druze showed fivefold and twofold higher frequencies than Jews and Moslems, respectively. Specifically, allelic frequencies of TPMT*3A were 0.73% (95% CI 0.34-1.45%), 0.79% (95% CI 0.16-2.39%), and 3.19% (95% CI 1.78-5.58%) in Jews, Moslems, and Druze, respectively. Although not found in Jews, TPMT*3C was found at an allelic frequency of 1.05% (95% CI 0.31-2.76%) and 0.75% (95% CI 0.02-2.84%) in Moslems and Druze. TPMT*2 and TPMT*3B were not detected in any of the Israeli subpopulations studied. CONCLUSION: These data indicate that the Israeli population displays a distinct TPMT genetic variability that is comprised of a mix of three major genetically diverse subpopulations, each with its unique TPMT allelic frequency distribution pattern and likelihood of developing an adverse reaction to thiopurine drugs.

Molecular mechanisms of epithelial cell-specific expression and regulation of the human anion exchanger (pendrin) gene.

Pendrin, a Cl(-)/anion exchanger encoded by the gene PDS, is highly expressed in the kidney, thyroid, and inner ear epithelia and is essential for bicarbonate secretion, iodide accumulation, and endolymph ion balance, respectively. This study aimed to define promoter regulatory elements essential for renal, thyroid, and inner ear epithelial cell-specific expression of human PDS (hPDS) and to explore the effect of ambient pH and aldosterone on hPDS promoter activity. Endogenous pendrin mRNA and protein were detected in renal HEK293, thyroid LA2, and inner ear VOT36 epithelial cell lines, but not in the fibroblast cell line, NIH3T3. A 4.2-kb hPDS 5'-flanking DNA sequence and consecutive 5'-deletion products were cloned into luciferase reporter vectors and transiently transfected into the above cell lines. Distinct differences in expression/activity of deduced positive/negative regulatory elements within the hPDS promoter between HEK293, LA2, and VOT36 cells were demonstrated, with only basal activity in NIH3T3 cells. Acidic pH (7.0-7.1) decreased and alkaline pH (7.6-7.7) increased hPDS promoter activity in transfected HEK293 and VOT36, but not in LA2 cells. Aldosterone (10(-8) M) reduced hPDS promoter activity in HEK293 but had no effect in LA2 and VOT36 cells. These pH and aldosterone-induced effects on the hPDS promoter occurred within 96-bp and 89-bp regions, respectively, which likely contain distinct response elements to these modulators. Acidic pH and aldosterone decreased, and alkaline pH increased, endogenous pendrin mRNA level in HEK293 cells. In conclusion, pendrin-mediated HCO3(-) secretion in the renal tubule and anion transport in the endolymph may be regulated transcriptionally by systemic pH and aldosterone.

Autosomal recessive renal proximal tubulopathy and hypercalciuria: a new syndrome.

BACKGROUND: The best described primary inherited proximal tubulopathies include X-linked hypercalciuric nephrolithiasis (XLHN), caused by a mutation in the chloride channel gene CLCN5, and classic Fanconi's syndrome, the genetic basis of which is unknown. The aim of this study is to examine the clinical, biochemical, and genetic characteristics of a highly consanguineous Druze family with autosomal recessive proximal tubulopathy and hypercalciuria (ARPTH), a syndrome not reported previously. METHODS: Three children (2 girls, 1 boy) of the family referred for evaluation of renal glycosuria and hypercalciuria and 10 of their close relatives were evaluated clinically and biochemically. All study participants underwent genetic analysis to exclude involvement of the CLCN5 gene. RESULTS: Evaluation of the 3 affected children showed glycosuria, generalized aminoaciduria, hypouricemia, uricosuria, low molecular weight (LMW) proteinuria, and hypercalciuria in all 3 children and phosphaturia in 2 children. They had no metabolic acidosis or renal insufficiency. One affected girl had nephrocalcinosis. Two children had a history of growth retardation and radiological findings of metabolic bone disease. Parathyroid hormone and 1,25-dihydroxyvitamin D [1,25(OH)2Vit D] blood levels in affected children were normal. Unaffected family members examined had no renal tubular defects or LMW proteinuria. Genetic linkage analysis excluded cosegregation of the ARPTH phenotype with the CLCN5 locus. CONCLUSION: ARPTH is a new syndrome characterized by nonacidotic proximal tubulopathy, hypercalciuria, metabolic bone disease, and growth retardation. It can be distinguished from XLHN by its autosomal recessive mode of inheritance and normal serum levels of calciotropic hormones, as well as the absence of LMW proteinuria in obligate carriers. The gene mutated in ARPTH remains to be identified.