Features and patterns of changes in neurochemical parameters at different stages of chronic mercury intoxication

Introduction. At present, the features of the clinical picture and pathogenesis of the formation and progression of chronic intoxication under the influence of mercury remain insufficiently studied. Purpose. To study the features and patterns of changes in the neurotransmitters and neurotrophic factors concentration at different stages of chronic mercury intoxication (CMI). Materials and methods. A cohort examination of 69 workers (group 1) exposed to mercury, 18 individuals in the initial period of CMI (group 2), and 55 patients in the long-term period (group 3) were carried out. The content of neurotransmitters and neurotrophic factors was determined by enzyme immunoassay. The statistical processing included Wilcoxon, Kruskal-Wallis and Mann-Whitney tests. Results. Higher levels of histamine were found in group 2, low levels of metanephrine in group 1, and normetanephrine in group 3. An increase in the BDNF concentration was revealed in group 2 compared with groups 1 and 3. The content of neurotrophin-3 in group 3 was statistically significantly lower than in group 2. Conclusion. The general pattern for all stages is an increase in the norepinephrine and CNTF concentration. Mercury neurointoxication at all stages is characterized by high serotonin levels. A distinctive feature for trained workers is a compensatory increase in the normetanephrine level and a low BDNF and NT-3. For the initial period of CMI, an increase in the histamine, BDNF and NT-3 content is characteristic. The long-term period is characterized by an imbalance in the concentration of the studied neurotransmitters and neurotrophic factors.

The interrelation of neurophysiological, psychological, and biochemical indicators in patients with occupational chronic mercury intoxication suffering from insomnia

Introduction. Despite the apparent connection of the existing neurological disorders and changes in the psycho-emotional sphere with sleep disorders in patients with chronic mercury intoxication (CRI), these relationships remain the least studied in the clinic neurointoxications. The study aimed to establish a connection between neurophysiological, biochemical, and psychopathological indicators in patients with occupational chronic mercury intoxication and insomnia. Materials and methods. Thirty-six patients took part in the examination in the remote period of CRI. The average age of patients in this group was 50.7±1.05 years, with an average work experience of 14.7±1.05. The authors carried out a psychological examination to determine the levels of depression, anxiety, asthenic state, computed electroencephalography (EEG), cognitive evoked potentials (CEP), polysomnography, the level of neurotransmitters. Results. The study showed that asthenization, when exposed to mercury, occurs due to a decrease in the limbic-hypothalamo-reticular complex activity (the presence of equivalent dipole sources of pathological activity in the area of diencephalic formations (thalamus, hypothalamus) in 56.2±5.6% of cases. The study showed a decrease in activity cerebral cortex, confirmed by weakening the coherent connections of the α-range in the occipital, central and frontal leads according to the data of coherent EEG analysis and changes on the part of the CEP. There was a direct correlation between the level of total sleep time and the serotonin level (rs=0.45), an inverse relationship between the level of depression and histamine level (rs=-0.56). Conclusion. The studies carried out to make it possible to establish the mechanisms of insomnia disorders in chronic mercury intoxication, which cause a weakening of the tone of the cerebral cortex and changes in neurotransmitter metabolism, as well as disorders of the reticular system with limbic structures. The study showed a close direct relationship between neurophysiological, psychological, and biochemical parameters in implementing insomnia in patients with chronic mercury intoxication.

Analysis of relationships between biochemical markers of endothelial dysfunction in chronic mercury exposure

Introduction. The cause of the development of endothelial dysfunction (ED) and, as a result, the pathology of the cardiovascular system may be exposure to mercury. The aim of study is to study the relationship between ED markers in individuals exposed to mercury. Materials and methods. A survey was carried out using biochemical and statistical methods in persons exposed to mercury with more than five years of work experience, and in patients with chronic mercury intoxication in the long-term post-exposure period. Results. Relationships of biochemical indicators of ED of various directions have been established, indicating the presence of pathological changes in the endothelium of vessels in which its different links are involved. Conclusions. Associations were established between the exposition load and the concentration of ED markers in workers without occupational disease, which indicates the contribution of production factors to its formation during contact with the toxicant. The results of the study of the correlation of biochemical indicators of ED indicate the presence of complex associations that form a closed system between its markers at the stage before the formation of occupational disease, and their disunity in the distant period of chronic mercury intoxication, especially in the presence of CVD.

Role of intercellular adhesion molecules and antibodies to oxidized LDL in pathogenesis of cardiovascular diseases under mercury exposure

Introduction. Exposure to mercury and its compounds can be a risk factor for the development of cardiovascular diseases. The aim of the study is to investigate the levels of antibodies to oxidized LDL, intercellular adhesion molecules sICAM-1, sVCAM-1, and VEGF in individuals exposed to mercury. Material and Methods. A cross-sectional examination was carried out using biochemical methods in persons who have come into contact with metallic mercury with a work experience of more than five years, persons with a first established diagnosis of chronic mercury intoxication, and patients with chronic mercury intoxication in the long-term postexposure period. Results. In persons exposed to mercury with concomitant cardiovascular diseases, the level of sVCAM-1 differed depending on the presence/absence of intoxication and acquired maximum values in its long-term period, while the concentrations of sICAM-1 and antibodies to oxidized LDL did not differ significantly. In the groups without cardiovascular pathology exposed to mercury, the concentration of sVCAM-1 was higher in patients with intoxication, and sICAM-1 was 1.5-2 times lower when compared with experienced individuals, the level of antibodies to oxidized LDL was maximum in the presence of intoxication in its initial period. Discussion. The progression of chronic mercury intoxication is accompanied by an increase in the level of sVCAM-1, and a gradual decrease in the content of sICAM-1 to reference values. Trained workers were found to have elevated sICAM-1 levels. Conclusion. The role of antibodies to oxidized LDL, intercellular adhesion molecules is their multidirectional participation in the mechanisms that inhibit or contribute to the formation of cardiovascular pathology in individuals exposed to mercury.

Pharmacotherapy of insomnia in patients with occupational chronic mercury intoxication

Introduction. Among occupational poisoning, chronic mercury intoxication (CMI) in the Irkutsk region occupies a leading position. Objective. To give a comparative analysis of the methods of pharmacotherapy of sleep disorders in patients in the long-term CRI. Material and methods. The study included 60 patients with long-term CRI, divided into two equal groups of 30 cases: in the first, the average age was 56.0 ± 0.7, in the second, the average age was 57.1 ± 3.0. Questionnaires were conducted using the hospital scale of anxiety and depression, electroencephalographic, polysomnographic studies before and after treatment. During the study, two treatment regimens for sleep disorders were implemented: the first regimen included the administration of an antidepressant (trazodone) and the chemical analog of melatonin (melaxen), and the second regimen was zolpidem. Statistical processing of the research results was carried out using the software package “Statistica 6.0”. Results. After treatment, in the first group there was an increase in the duration of the total sleep time (p = 0.0008), a decrease in the time of falling asleep (p = 0.004), a decrease in the total number of activations (p = 0.00005), and the time of wakefulness in bed (p = 0.0018), an increase in the representation of delta sleep (p = 0.03), and REM sleep (p = 0.004), an increase in the sleep efficiency index (p = 0.0008), and a decrease in the integrative sleep quality index (p = 0.001). In the second group, only a decrease in the latent period of stage 1 (time of falling asleep) was established (p = 0.05). Discussion. After treatment with trazodone in combination with melaxen, a decrease in the severity of presomnic and intrasomnic disorders was found, and in patients taking zolpidem, only the severity of presomnic disorders was reduced. The results confirm the hypothesized cause of dissominal disorders in CRI (changes in the activity of the limbic-reticular complex). Conclusion. The use of trazodone in combination with melaxen proves the improvement of the qualitative and quantitative indices of the structure of night sleep in patients in the long-term postexposure period of CRI.

Comparative assessment of cardiac-specific autoantibodies levels in persons with occupational pathology caused by exposure to physical and chemical factors

Introduction. The pathology of the cardiovascular system is one of the dominant causes of mortality. It has been established that exposure to vibration and mercury is associated with the development of heart and vascular diseases. Specific autoantibodies can be used as markers of exposure effects. The aim of the work was a comparative assessment of the levels of cardiac-specific autoantibodies in individuals with vibrational disease (VD) and chronic mercury intoxication. Material and methods. We examined VD patients, with chronic mercury intoxication (CMI), who work in contact with a toxicant and in the long-term post-exposure period, and the comparison group. The relative content of specific autoantibodies to nitric oxide synthase (NOS), platelet membrane components (PMC), neutrophil cytoplasm, and vascular endothelial cell antigens (c-ANCA), plasminogen, collagen, and PAPP-A protein were studied in the patient’s blood serum. Results. In individuals with CMI, the levels of autoantibodies PCM, c-ANCA are lower for plasminogen and higher for collagen than in the comparison group and in VD patients. Elevated levels of anti-collagen antibodies were found in 70% of individuals with CMI. Among patients with CMI, elevated levels of antibodies to NOS were found in 60% of persons exposed to mercury and were not detected in the long-term post-exposure period. Discussion. The high frequency of elevated levels of antibodies to collagen and correlations between their level and the rest of the indices may indicate its important role in the development of endothelial dysfunction in persons with CMI. Elevated levels of autoantibodies to NOS in patients exposed to mercury are accompanied by a decrease in NO levels and may be an important part of the pathogenesis of endothelial dysfunction. Conclusion. The profile of cardiac-specific autoantibodies in VD patients is similar to that in the comparison group. Elevated levels of antibodies to collagen and decreased levels of antigens of platelets and plasminogen play an important role in the development of endothelial dysfunction in patients with CMI. The high frequency of hyper immunoreactivity of autoantibodies to NOS and c-ANCA, which is observed in patients with CMI who are in contact with a toxicant, decreases in the long-term post-exposure period.

Health Impact Assessment of Artisanal and Small-Scale Gold Mining Area in Myanmar, Mandalay Region: Preliminary Research

Increasing artisanal and small-scale gold mining (ASGM) in developing countries has raised health concerns in mining communities. A preliminary health survey was conducted in Thabeikkyin Township, Mandalay Region, Myanmar, in February 2020 to assess the health conditions of an ASGM community. Respiratory function and other clinical assessments were evaluated in miners and non-miners, and participants’ hair was analyzed for heavy metals. Respiratory function of miners was similar to that of non-miners. However, miners’ respiratory function declined with longer mining activity duration. In total, 3 out of 18 miners showed neurological signs and symptoms of chronic mercury intoxication. The median concentration of the hair mercury was significantly higher in miners than non-miners (P = 0.01), and 9 out of 18 miners and 2 out of 11 non-miners showed the warning level of mercury. We found that, despite an association between declining respiratory function and length of time mining, only a minority of miners showed clinical features of chronic mercury intoxication. Further clinical surveys with a larger sample size are necessary to determine the broader health status of this community. In addition, clinical indicators such as pulmonary function tests are recommended as additional criteria for the diagnosis of mercury intoxication.

Health-related quality of life (EQ-5D + C) among people living in artisanal and small-scale gold mining areas in Zimbabwe: a cross-sectional study

Background In Zimbabwe, an estimated 500,000 people work in the sector of artisanal and small-scale gold mining (ASGM). Two million Zimbabweans are dependent on this sector. Using mercury is common to extract gold from ore. Long term exposure to mercury can cause various adverse health conditions including chronic mercury intoxication. The influence of these adverse health effects on the health-related quality of life (HRQoL) is still unknown. The aim of this study is to assess the HRQoL of people who identify themselves as miners, and to analyze potential influencing factors, such as age, years of working with mercury and health conditions caused by mercury exposure. Methods This cross-sectional study assessed the HRQoL using the standardized EQ-5D + C (3 L) questionnaire and collected human specimens (blood, urine) of people living and possibly working in ASGM areas in Zimbabwe. Factors such as age, years of working with mercury and adverse health conditions possibly caused by mercury exposure were analyzed with regards to their influence on the HRQoL. Results The 207 participants (82% male, mean age 38 years) reported 40 different health states. Of the study participants 42.5% reported to be in complete good health while 57.5% reported being unwell in different ways. Nine participants (4.3%) were identified with chronic mercury intoxication, whereas 92 participants (33.3%) had mercury levels above the “Alert” threshold in at least one specimen. Having chronic mercury intoxication has a significant negative influence on the HRQoL, when taking into account age, gender and years of working with mercury. Cognitive problems were the most reported in the questionnaire, however, the association between this domain separately and the HRQoL was not verified. Conclusion This study shows that adverse health effects caused by chronic exposure to mercury, have a negative influence on the HRQoL among people living in ASGM areas.

Clinical management of chronic mercury intoxication secondary to skin lightening products: A proposed algorithm

Mercury is a toxic substance that is commonly used in skin lightening products. Various effects on humans have been observed, which affect both users and non-users. Many cases reported delayed diagnosis and treatment, even after weeks of hospitalization. The possible reasons are non-specific clinical manifestation and lack of awareness and knowledge regarding chronic mercury intoxication secondary to skin lightening products. A thorough history of mercury exposure is crucial. Physical assessment and relevant supporting tests are indicated to establish a diagnosis. Blood and urine mercury levels are an essential examination for diagnosis and monitoring of the progress and response to treatment. The primary treatment is the discontinuation of the skin lightening products. Chelation therapy is not mandatory and usually indicated for symptomatic patients. The prognosis depends on the duration of the product use, concentration of mercury in the skin product, and the severity of the clinical presentation.