Cadmium: A possible etiological factor in peripheral polyneuropathy

Uncovering the exact cause of polyneuropathies seems to be impossible in up to 24% of the cases. Experimental studies have shown that cadmium (Cd), which is a well-known occupational and environmental hazard, can be a potent neurotoxicant for the peripheral nervous system. Moreover, Cd has a half-life of more than 15 years in humans. We hypothesize that older workers may be more susceptible to an increased Cd body burden, and may develop a peripheral polyneuropathy (PNP) over time. A blinded epidemiological survey was performed in 13 retired, long-term Cd-exposed workers and 19 age-matched controls. Historical Cd biomonitoring data were available over the last two decades. A neurological clinical examination, nerve conduction studies, and needle EMG were performed and a standardized questionnaire was given to evaluate polyneuropathy complaints. if two of the following four criteria, i.e. complaints of polyneuropathy, neurophysiological changes compatible with polyneuropathy, distal symmetrical areflexia, or distal symmetrical anesthesia for vibration sense, temperature or blunt-sharp discrimination were present the diagnosis of PNP was made. Two (11%) of the control and seven (54%) of the retired Cd workers met the PNP criteria OR: 9.92 (95%CI 1.60-61.6) Fisher exact test p=0.015. The existence of a polyneuropathy was related to the level of the Cd body burden as reflected by urinary Cd multiple logistic regression p=0.016, OR=1.26, (95%CI, 1.04-1.51), but not to blood lead (p=0.352). Our findings favour the hypothesis of a promoting role of increased cadmium body burden in the development of PNP at older age. (C) 1999 Intox Press, Inc

Neuroblastoma mRNAs Predict Outcome in Children With Stage 4 Neuroblastoma: A European HR-NBL1/SIOPEN Study

Purpose: To evaluate the hypothesis that detection of neuroblastoma mRNAs by reverse transcriptase quantitative polymerase chain reaction (RTqPCR) in peripheral blood (PB) and bone marrow aspirates (BM) from children with stage 4 neuroblastoma are clinically useful biomarkers of risk. Methods: RTqPCR for paired-like homeobox 2b (PHOX2B), tyrosine hydroxylase (TH), and doublecortin (DCX) mRNA in PB and BM of children enrolled onto the High-Risk Neuroblastoma Trial-1 of the European Society of Pediatric Oncology Neuroblastoma Group (HR-NBL1/SIOPEN) was performed at diagnosis and after induction therapy. Results: High levels of TH, PHOX2B, or DCX mRNA in PB or BM at diagnosis strongly predicted for worse event-free survival (EFS) and overall survival (OS) in a cohort of 290 children. After induction therapy, high levels of these mRNAs predicted worse EFS and OS in BM but not in PB. Combinations of mRNAs in BM did not add to the predictive power of any single mRNA. However, in the original (n = 182) and validation (n = 137) PB cohorts, high TH (log10TH > 0.8) or high PHOX2B (log10PHOX2B > 0.28) identify 19% of children as ultrahigh risk, with 5-year EFS and OS rates of 0%; OS rate was 25% (95% CI, 16% to 36%) and EFS rate was 38% (95% CI, 28% to 49%) in the remaining children. The magnitude of reduction in mRNA level between diagnosis and postinduction therapy in BM or PB was not of additional predictive value. Conclusion: High levels of TH and PHOX2B mRNA in PB at diagnosis objectively identify children with ultrahigh-risk disease who may benefit from novel treatment approaches. The level of TH, PHOX2B, and DCX mRNA in BM and/or PB at diagnosis might contribute to an algorithm to improve stratification of children for treatment

Mitochondrial uncouplers inhibit clathrin-mediated endocytosis largely through cytoplasmic acidification

ATP production requires the establishment of an electrochemical proton gradient across the inner mitochondrial membrane. Mitochondrial uncouplers dissipate this proton gradient and disrupt numerous cellular processes, including vesicular trafficking, mainly through energy depletion. Here we show that Endosidin9 (ES9), a novel mitochondrial uncoupler, is a potent inhibitor of clathrin-mediated endocytosis (CME) in different systems and that ES9 induces inhibition of CME not because of its effect on cellular ATP, but rather due to its protonophore activity that leads to cytoplasm acidification. We show that the known tyrosine kinase inhibitor tyrphostinA23, which is routinely used to block CME, displays similar properties, thus questioning its use as a specific inhibitor of cargo recognition by the AP-2 adaptor complex via tyrosine motif-based endocytosis signals. Furthermore, we show that cytoplasm acidification dramatically affects the dynamics and recruitment of clathrin and associated adaptors, and leads to reduction of phosphatidylinositol 4,5-biphosphate from the plasma membrane

Mitochondrial uncouplers inhibit clathrin-mediated endocytosis largely through cytoplasmic acidification

ATP production requires the establishment of an electrochemical proton gradient across the inner mitochondrial membrane. Mitochondrial uncouplers dissipate this proton gradient and disrupt numerous cellular processes, including vesicular trafficking, mainly through energy depletion. Here we show that Endosidin9 (ES9), a novel mitochondrial uncoupler, is a potent inhibitor of clathrin-mediated endocytosis (CME) in different systems and that ES9 induces inhibition of CME not because of its effect on cellular ATP, but rather due to its protonophore activity that leads to cytoplasm acidification. We show that the known tyrosine kinase inhibitor tyrphostinA23, which is routinely used to block CME, displays similar properties, thus questioning its use as a specific inhibitor of cargo recognition by the AP-2 adaptor complex via tyrosine motif-based endocytosis signals. Furthermore, we show that cytoplasm acidification dramatically affects the dynamics and recruitment of clathrin and associated adaptors, and leads to reduction of phosphatidylinositol 4,5-biphosphate from the plasma membrane.status: publishe