Breathing pattern, lung inflation reflex and airway tone in acrylamide neuropathy

Association of acrylamide hemoglobin biomarkers with chronic obstructive pulmonary disease in the general population in the US: NHANES 2013-2016

Background: Acrylamide is a well-known potential carcinogenic compound formed as an intermediate in the Maillard reaction during heat treatment, mainly from high-temperature frying, and is found in baked goods and coffee, as well as resulting from water treatment, textiles and paper processing. The effects of acrylamide on lung disease in humans remains unclear. We aimed to investigate the association between blood acrylamide and glycidamide and chronic obstructive pulmonary disease (COPD) in the United States of America (U.S.) population using PROC logistic regression models. Results: 2744 participants aged 20 to 80 from the 2013-2016 National Health and Nutrition Examination Survey (NHANES) were enrolled. After adjusting for demographic data, health factors and serum cotinine, the ratio of HbGA to HbAA (HbGA/HbAA) significantly increased the risk of COPD (P for trend = 0.022). The odds ratio (OR) with a 95% confidence interval (95% CI) for HbGA/HbAA in the third tile was 2.45 (1.12-5.31), compared with the lowest tile. The restricted cubic spline (RCS) curve showed a positive linear correlation between the log (HbGA/HbAA) and the risk of COPD (P = 0.030). Conclusion: The ratio of glycidamide and acrylamide (HbGA/HbAA) was associated with COPD. This association was more prominent in males, obese individuals, people with a poverty income ratio (PIR) < 1.85 or people who never exercise. However, null associations were observed between HbAA, HbGA and HbAA + HbGA, and COPD.

Orphan Peripheral Neuropathies

Objectives:

Generally, neuropathies of peripheral nerves are a frequent condition (prevalence 2–3%) and most frequently due to alcoholism, diabetes, renal insufficiency, malignancy, toxins, or drugs. However, the vast majority of neuropathies has orphan status. This review focuses on the etiology, frequency, diagnosis, and treatment of orphan neuropathies.

Methods:

Literature review

Results:

Rareness of diseases is not uniformly defined but in the US an orphan disease is diagnosed if the prevalence is <1:200000, in Europe if <5:10000. Most acquired and hereditary neuropathies are orphan diseases. Often the causative variant has been reported only in a single patient or family, particularly the ones that are newly detected (e.g. SEPT9, SORD). Among the complex neuropathies (hereditary multisystem disorders with concomitant neuropathies) orphan forms have been reported among mitochondrial disorders (e.g. NARP, MNGIE, SANDO), spinocerebellar ataxias (e.g. TMEM240), hereditary spastic paraplegias (e.g UBAP1), lysosomal storage disease (e.g. Schindler disease), peroxisomal disorders, porphyrias, and other types (e.g. giant axonal neuropathy, Tangier disease). Orphan acquired neuropathies include the metabolic neuropathies (e.g. vitamin-B1, folic acid), toxic neuropathies (e.g. copper, lithium, lead, arsenic, thallium, mercury), infectious neuropathies, immune-mediated (e.g. Bruns-Garland syndrome), and neoplastic/paraneoplastic neuropathies.

Conclusions:

Though orphan neuropathies are rare per definition they constitute the majority of neuropathies and should be considered as some of them are easy to identify and potentially treatable, as clarification of the underlying cause may contribute to the knowledge about etiology and pathophysiology of these conditions, and as the true prevalence may become obvious only if all ever diagnosed cases are reported.

Acrylamide: review of toxicity data and dose-response analyses for cancer and noncancer effects

Acrylamide (ACR) is used in the manufacture of polyacrylamides and has recently been shown to form when foods, typically containing certain nutrients, are cooked at normal cooking temperatures (e.g., frying, grilling or baking). The toxicity of ACR has been extensively investigated. The major findings of these studies indicate that ACR is neurotoxic in animals and humans, and it has been shown to be a reproductive toxicant in animal models and a rodent carcinogen. Several reviews of ACR toxicity have been conducted and ACR has been categorized as to its potential to be a human carcinogen in these reviews. Allowable levels based on the toxicity data concurrently available had been developed by the U.S. EPA. New data have been published since the U.S. EPA review in 1991. The purpose of this investigation was to review the toxicity data, identify any new relevant data, and select those data to be used in dose-response modeling. Proposed revised cancer and noncancer toxicity values were estimated using the newest U.S. EPA guidelines for cancer risk assessment and noncancer hazard assessment. Assessment of noncancer endpoints using benchmark models resulted in a reference dose (RfD) of 0.83 microg/kg/day based on reproductive effects, and 1.2 microg/kg/day based on neurotoxicity. Thyroid tumors in male and female rats were the only endpoint relevant to human health and were selected to estimate the point of departure (POD) using the multistage model. Because the mode of action of acrylamide in thyroid tumor formation is not known with certainty, both linear and nonlinear low-dose extrapolations were conducted under the assumption that glycidamide or ACR, respectively, were the active agent. Under the U.S. EPA guidelines (2005), when a chemical produces rodent tumors by a nonlinear or threshold mode of action, an RfD is calculated using the most relevant POD and application of uncertainty factors. The RfD was estimated to be 1.5 microg/kg/day based on the use of the area under the curve (AUC) for ACR hemoglobin adducts under the assumption that the parent, ACR, is the proximate carcinogen in rodents by a nonlinear mode of action. When the mode of action in assumed to be linear in the low-dose region, a risk-specific dose corresponding to a specified level of risk (e.g., 1 x 10-5) is estimated, and, in the case of ACR, was 9.5 x 10-2 microg ACR/kg/day based on the use of the AUC for glycidamide adduct data. However, it should be noted that although this review was intended to be comprehensive, it is not exhaustive, as new data are being published continuously.

Selective vagal afferent dysfunction in dogs with congenital idiopathic megaoesophagus

Congenital idiopathic megaoesophagus (CIM) is a rare, naturally occurring disorder of the dog that is characterised by deficient motility and dilatation of the oesophagus. Recent studies indicate that the vagal sensory system mediating reflexes induced by oesophageal distension is defective in, and may underlie the pathomechanism of this disorder. We sought to establish whether other distension sensitive vagal afferent systems were impaired in CIM, or whether the vagal afferent dysfunction was selective. Thus, we examined the Hering-Breuer lung inflation reflex (HBR), which is subserved by a contiguous and physiologically similar vagal afferent system, in five dogs with CIM in which oesophageal vagal afferent dysfunction had been demonstrated. At varying levels of lung inflation, we found the HBR to be normally graded and of normal strength in affected dogs and that this result was unlikely to be influenced by other factors known to alter the strength of the reflex. These observations provide evidence for an organ specific, selective vagal afferent dysfunction in dogs with CIM. It is possible that similar processes may be active in disorders of visceral organ systems subserved by vagal afferents in other species, including man.

Effects of acrylamide on cotransmission in perivascular sympathetic and sensory nerves

The effects of chronic administration of acrylamide on sympathetic and sensory nerves were examined in the mesenteric artery of rabbits. The noradrenaline (NA) content of the artery was significantly decreased and the total contractile response to electrical field stimulation (4-64 Hz) markedly reduced in the acrylamide group. This was not due to an impairment of the contractility of the smooth muscle or to alterations in the postjunctional receptors. At 16 Hz, only the purinergic component of sympathetic cotransmission was significantly reduced by acrylamide. At 64 Hz, both the purinergic and the adrenergic components were significantly decreased. Field stimulation of the artery pretreated with guanethidine and precontracted with NA produced a frequency-dependent relaxation which was prevented by capsaicin and thus mediated by perivascular sensory nerves. In contrast to its effects on sympathetic cotransmission, acrylamide resulted in a trend, although not significant, towards increased responses at each frequency studied (2-16 Hz). 2-Methylthio-ATP (2Me-S-ATP) caused significantly greater relaxation following acrylamide treatment while vasodilator responses to calcitonin gene-related peptide and substance P were unchanged. It is concluded that, in addition to its known action in producing neuropathy in myelinated somatic motor and sensory nerves, acrylamide causes damage to unmyelinated perivascular sympathetic fibres. Purinergic mechanisms may be particularly susceptible to acrylamide since both the purinergic component of sympathetic vasoconstriction and the relaxation in response to 2Me-S-ATP were affected by acrylamide treatment.

Continuous ambulatory electrocardiography among workers exposed to methylmethacrylate

Methylmethacrylate (MMA), a widely used monomer in the manufacture of acrylic polymers, has been reported to cause cardiac troubles in industrial workers. The effects of MMA on the heart was assessed by continuous ambulatory electrocardiographic records. The study was performed in 22 occupationally exposed workers and in 18 healthy controls. Our study did not support the hypothesis that MMA is responsible for cardiomyodystrophy. However, supraventricular and ventricular ectopic beats were significantly more frequent among exposed workers versus controls (P < 0.01). Moreover, repolarization changes such as large T waves were noted only in exposed workers (eight cases against none in the control group). Although there was no clear connection between MMA exposure and the recorded cardiac changes in the exposed group, the role of MMA cannot be totally excluded.

Changes in sympathetic and endothelium-mediated responses in the rabbit central ear artery after acrylamide treatment

The effect of acrylamide intoxication on the innervation and local control of the rabbit central ear artery was investigated. There was no difference in the noradrenaline, neuropeptide Y and calcitonin gene-related peptide tissue content between control and experimental animals. There was, however, a slight reduction in catecholamine histofluorescence. Although the contractile efficiency of the rabbit central ear artery as measured by responses to potassium chloride was unchanged, nerve-mediated contractile responses were significantly attenuated in acrylamide-treated animals. Contractile responses induced by exogenous alpha,beta-methylene ATP were markedly increased after acrylamide treatment, in contrast to contractions induced by exogenous noradrenaline which were attenuated at maximal concentrations. Modulatory effects of nerve-mediated contractile responses by neuropeptide Y were unaffected by acrylamide intoxication. It therefore appears that acrylamide intoxication damages sympathetic cotransmission, perhaps with preferential action on the purinergic component. Endothelium-dependent relaxant responses to acetylcholine and substance P were attenuated in acrylamide-treated animals, whereas relaxant responses mediated by calcitonin gene-related peptide (endothelium independent) were unaffected. The question of whether the damage to the endothelial cell action is a primary effect, or a secondary consequence of sympathetic nerve damage, is discussed.

Abnormal cough reflex in canine acrylamide neuropathy

Coughing in response to irritation of the airways is a fundamental protective reflex that is dependent on rapidly adapting bronchopulmonary receptors and their vagal afferent fibers; reflex airway constriction, which is effected by vagomotor efferent fibers, usually accompanies coughing. Although dysfunction of vagally mediated cardiovascular and gastrointestinal reflexes is a well-documented complication of autonomic neuropathy, to date there have been no studies of the effect of peripheral autonomic failure on the cough reflex. In the study reported here, we examined the effect of acrylamide-induced neuropathy, a distal axonopathy, on the ventilatory and tracheomotor components of the cough reflex in conscious dogs. There was a reduction in the cough reflex in response to mechanical irritation of the large airways in the preclinical phase of the neuropathy, and the cough reflex was virtually abolished when the dogs had moderate neuropathy. Following withdrawal of the neurotoxin, there was a substantial recovery of the cough reflex in surviving animals. It is possible that the cough reflex may be reduced in patients with vagal neuropathy and that this might compromise protection of the airway.