Diabetic Retinopathy Screening in Patients with Diabetes Using a Handheld Fundus Camera: The Experience from the South-Eastern Region in Hungary

PURPOSE

Diabetic retinopathy (DR) is the leading cause of vision loss among active adults in industrialized countries. We aimed to investigate the prevalence of diabetes mellitus (DM), DR and its different grades, in patients with DM in the Csongrád County, South-Eastern region, Hungary. Furthermore, we aimed to detect the risk factors for developing DR and the diabetology/ophthalmology screening patterns and frequencies, as well as the effect of socioeconomic status- (SES-) related factors on the health and behavior of DM patients.

METHODS

A cross-sectional study was conducted on adults (>18 years) involving handheld fundus camera screening (Smartscope Pro Optomed, Finland) and image assessment using the Spectra DR software (Health Intelligence, England). Self-completed questionnaires on self-perceived health status (SPHS) and health behavior, as well as visual acuity, HbA1c level, type of DM, and attendance at healthcare services were also recorded.

RESULTS

787 participants with fundus camera images and full self-administered questionnaires were included in the study; 46.2% of the images were unassessable. T1D and T2D were present in 13.5% and 86.5% of the participants, respectively. Among the T1D and T2D patients, 25.0% and 33.5% had DR, respectively. The SES showed significant proportion differences in the T1D group. Lower education was associated with a lower DR rate compared to non-DR (7.7% vs. 40.5%), while bad/very bad perceived financial status was associated with significantly higher DR proportion compared to non-DR (63.6% vs. 22.2%). Neither the SPHS nor the health behavior showed a significant relationship with the disease for both DM groups. Mild nonproliferative retinopathy without maculopathy (R1M0) was detected in 6% and 23% of the T1D and T2D patients having DR, respectively; R1 with maculopathy (R1M1) was present in 82% and 66% of the T1D and T2D groups, respectively. Both moderate nonproliferative retinopathy with maculopathy (R2M1) and active proliferative retinopathy with maculopathy (R3M1) were detected in 6% and 7% of the T1D and T2D patients having DR, respectively. The level of HbA1c affected the attendance at the diabetology screening (HbA1c > 7% associated with >50% of all quarter-yearly attendance in DM patients, and with 10% of the diabetology screening nonattendance).

CONCLUSION

The prevalence of DM and DR in the studied population in Hungary followed the country trend, with a slightly higher sight-threatening DR than the previously reported national average. SES appears to affect the DR rate, in particular, for T1D. Although DR screening using handheld cameras seems to be simple and dynamic, much training and experience, as well as overcoming the issue of decreased optic clarity is needed to achieve a proper level of image assessability, and in particular, for use in future telemedicine or artificial intelligence screening programs.

Diabetic Retinopathy Screening Using Telemedicine Tools: Pilot Study in Hungary

Introduction. Diabetic retinopathy (DR) is a sight-threatening complication of diabetes. Telemedicine tools can prevent blindness. We aimed to investigate the patients' satisfaction when using such tools (fundus camera examination) and the effect of demographic and socioeconomic factors on participation in screening. Methods. Pilot study involving fundus camera screening and self-administered questionnaire on participants' experience during fundus examination (comfort, reliability, and future interest in participation), as well as demographic and socioeconomic factors was performed on 89 patients with known diabetes in Csongrád County, a southeastern region of Hungary. Results. Thirty percent of the patients had never participated in any ophthalmological screening, while 25.7% had DR of some grade based upon a standard fundus camera examination and UK-based DR grading protocol (Spectra™ software). Large majority of the patients were satisfied with the screening and found it reliable and acceptable to undertake examination under pupil dilation; 67.3% were willing to undergo nonmydriatic fundus camera examination again. There was a statistically significant relationship between economic activity, education and marital status, and future interest in participation. Discussion. Participants found digital retinal screening to be reliable and satisfactory. Telemedicine can be a strong tool, supporting eye care professionals and allowing for faster and more comfortable DR screening.

The role of home smoking bans in limiting exposure to secondhand tobacco smoke in Hungary

Our objective was to assess how exposure to secondhand tobacco smoke occurs in Hungarian homes, particularly among non-smokers, and to examine the effectiveness of home smoking bans in eliminating exposure to secondhand smoke at home. In 2009, 2286 non-smokers and smokers aged 16-70 years, who were selected randomly from a nationally representative sample of 48 Hungarian settlements, completed paper-and-pencil self-administered questionnaires addressing tobacco-related attitudes, opinions and behaviors. Chi-square tests, one-way analysis of variance and multivariate logistic regression models were used to assess the effect of demographics, socio-economic characteristics and home smoking policies on the risk of exposure to secondhand tobacco smoke at home. Significantly higher risk of exposure was found among younger, lower educated and poorer people and among those having no or partial home smoking restrictions. There was a significant interaction between education level and home smoking policies: the effect of a smoking ban on exposure to secondhand tobacco smoke was stronger for the lower educated group than the higher educated group. The results suggest that Hungarians are making good progress in implementing home smoking bans, and that in the majority of population these bans are working. More can be done to promote the uptake of home smoking bans among poorer and less educated subpopulations.

Support for population level tobacco control policies in Hungary

BACKGROUND

Smoking is the leading, preventable risk factor for premature death and disability in Hungary. The objective of this paper was to assess the social acceptability of and the predictors of holding favourable attitudes toward tobacco control policies among the Hungarian population.

METHODS

A self-administered questionnaire-based study was carried out among individuals aged 16-70 years. Logistic regression analysis was used to assess whether support for the ten tobacco control policies varies as a function of age, sex, educational level, and smoking status.

RESULTS

The majority of the respondents supported the studied tobacco control measures. Over 90 percent of the sample supported: fines for retailers selling tobacco products to minors (92.3%), stricter enforcement of restrictions on selling tobacco products to minors (90.5%), and a ban on smoking in health care institutions (91.4%). The lowest levels of support were for bans on sponsorship by the tobacco industry (52.8%) and price increases on tobacco products (54.9%). For each measure, support was significantly lower among smokers than non-smokers. Age and education were significantly related to support for some but not all measures.

CONCLUSIONS

Strong majorities of Hungarians support the enactment and enforcement of a wide range of tobacco control measures, a fact that was acknowledged by Parliament's passage of the 2011 Anti-Smoking Law. Advocacy efforts to encourage the acceptance of tobacco control policies should focus not only on smokers, but also on younger and less educated non-smokers.

General and electrophysiological toxic effects of manganese in rats following subacute administration in dissolved and nanoparticle form

In an attempt to model occupational and environmental Mn exposures and their possible interaction, young male Wistar rats were exposed to Mn by oral administration in dissolved form (MnCl(2)·4H(2)O, 14.84 and 59.36 mg/kg b.w.) and by intratracheal application of MnO(2) nanoparticles (2.63 mg/kg b.w.). After 3 and 6 weeks oral, or 3 weeks oral plus 3 weeks intratracheal, exposure, general toxicological, and electrophysiological tests were done. Body weight gain was significantly reduced after 6 and 3 plus 3 weeks exposure, but the effect of the latter on the pace of weight gain was stronger. Organ weights signalized systemic stress and effect on lungs. Changes in evoked electrophysiological responses (cortical sensory evoked potential and nerve action potential) indicated that the 3 plus 3 weeks combined exposure caused equal or higher changes in the latency of these responses than 6 weeks of exposure, although the calculated summed Mn dose in the former case was lower. The results showed the importance of the physicochemical form of Mn in determining the toxic outcome, and suggested that neurofunctional markers of Mn action may indicate the human health effect better than conventional blood Mn measurement.

Nervous system effects in rats on subacute exposure by lead-containing nanoparticles via the airways

CONTEXT AND OBJECTIVE

Lead (Pb) is a heavy metal harmful for human health and environment. From leaded gasoline (still used in certain countries), and in Pb processing and reprocessing industries, airborne particles are emitted which can be inhaled. In such exposure, the size of particles entering the airways is crucial. The nervous system is a primary target for Pb, and consequences like occupational neuropathy and delayed mental development of children are well-known. The aim of this work was to investigate the neurotoxicity of Pb nanoparticles (NPs) applied into the airways of rats.

METHODS

Nano-sized lead oxide particles (mean diameter ca. 20 nm) were suspended in distilled water and instilled into the trachea of adult male Wistar rats (in doses equivalent to 2 and 4 mg/kg Pb), 5 times a week for 3 and 6 weeks. At the end, open field motility was tested, then central and peripheral nervous activity was recorded in urethane anesthesia.

RESULTS AND CONCLUSION

The treated rats' body weight gain was significantly lower than that of the controls from the 3rd week onwards, and the weight of their lungs was significantly increased. Horizontal motility increased while vertical motility decreased. Spontaneous cortical activity was shifted to higher frequencies. The somatosensory cortical evoked potential showed increased latency and decreased frequency-following ability, and similar alterations were seen in the tail nerve. Significant Pb deposition was measured in blood, brain, lung and liver samples of the treated rats. The experiments performed seem to constitute an adequate model of the human effects of inhaled Pb NPs.

Smoking behaviour and attitudes of Hungarian Roma and non-Roma population towards tobacco control policies

OBJECTIVES

To assess the smoking status and support for tobacco control policies among the Roma minority compared with the non-Roma population in Hungary.

METHODS

A cross-sectional survey was delivered among Roma minority and local non-Roma population; 83 Roma and 126 non-Roma people were interviewed. Chi-square tests and logistic regression were applied to compare Roma and non-Roma populations.

RESULTS

The prevalence of smoking was significantly higher and the support for tobacco control measures was significantly lower in the Roma population. This effect of ethnicity on attitudes toward tobacco control was explained somewhat, but not completely, by the Roma group's higher rate of smoking and lower level of education.

CONCLUSIONS

Tobacco control policies are a proven strategy for denormalizing smoking and discouraging initiation. This strategy has important potential for Roma communities because of their high rates of tobacco use. However, this study shows that the Roma are resistant the efforts to limit smoking. Changing these attitudes will require targeted public health interventions that take into account not only the lower educational levels of the Roma, but also their cultural beliefs regarding tobacco.

Determinants of health-promoting lifestyle behaviour in the rural areas of Hungary

Today chronic non-communicable diseases are the major cause of death and disability worldwide. Chronic diseases are determined by common risk factors (e.g. smoking). The purpose of this study was to develop a health-promoting behaviour index, and to evaluate the impact of the social and the demographic characteristics of the individuals, self-rated health and certain features of settlements on the score of this index. A population-based, cross-sectional health survey was conducted. Altogether 91 settlements with various sizes of population, and at various stages of social, economic and infrastructural development took part in the survey. The survey was based on interviewer-administered questionnaires, 3380 subjects filled in the questionnaires correctly, and the response rate was 82.4%. Questions on lifestyle factors referred to smoking, nutritional habits and physical activity. Low level (5.5%) of people have achieved the 'complete' health-promoting behaviour, including non-smoking, healthy nutrition and physical activity. There were significant associations between health-promoting behaviour and demographic, social and economic characteristics of the individuals and their dwelling place. The lower prevalence of healthy lifestyle activities among lower educated, lower income and aged people living in small settlements call the attention to the higher risk of these people. On planning interventions, special attention should be paid to the geographically, infrastructurally, socially and demographically disadvantaged population groups to provide equal opportunities for them, to live a healthy way of life. The application of the health-promoting index might be used to monitor the effects of interventions to alter lifestyle at community level.

Behavioral effects of subchronic inorganic manganese exposure in rats

BACKGROUND

Manganese, an essential micronutrient, is a potential neurotoxicant in prolonged overexposure. Parkinson-like syndrome, motor deficit, disturbed psychomotor development are typical signs of neuropathological alterations due to Mn in humans.

METHODS

Young adult rats, in three groups of 16 each, received 15 and 59 mg/kg b.w. MnCl(2), (control: distilled water) via gavage for 10 weeks, and were kept for further 12 weeks. Correlation of MnCl(2) exposure to body and organ weights, neurobehavioral effects (spatial memory, exploratory activity, psychomotor performance, pre-pulse inhibition), and histopathological changes (gliosis) was sought.

RESULTS

By the end of treatment, Mn accumulated in blood, cortex, hippocampus, and parenchymal tissues. Body and organ weights were reduced in high dose rats. All treated rats showed hypoactivity, decreased memory performance, and diminished sensorimotor reaction. In the dentate gyrus of these, GFAP immunoreactivity increased. During the post-treatment period, body weight of the high dose group remained decreased, locomotor activity returned to control, but the lasting effect of MnCl(2) could be revealed by amphetamine.

CONCLUSION

Using complex methodology, new data were obtained regarding the relationship between the long-term effects of MnCl(2) at neuronal and behavioral level.

[Applicability of the abbreviated version of the World Health Organization's quality of life questionnaire in Hungary]

INTRODUCTION

Quality of life, as a subjective parameter of the general condition, is suitable for characterization of the health status of populations or patient groups, and for studying the effects of therapeutic or preventive interventions.

AIMS

To test the applicability and reliability in Hungary of the abbreviated form of the quality of life questionnaire developed by WHO, one of several ways to measure the quality of life.

METHODS

Questionnaire-based cross-sectional investigation was performed among altogether 814 persons, in small settlements of population under 1000 and 2000, and in a small town for control, in Csongrád county, Hungary. The reliability and validity of the quality of life questionnaire was tested, within each group of questions, by means of Cronbach's alpha, ANOVA and Kruskal-Wallis tests, and by Spearman's rho correlation coefficient.

RESULTS

The mean values of the four domains of quality of life - physical, psychological, social and environmental - showed no noteworthy differences. The Cronbach's alpha figures of the internal consistency test on separate groups of questions and on all questions were in all cases above the expected minimum of 0.7. The means calculated for each domain of quality of life were decreasing with increasing age. Healthy people estimated each aspect of quality of life as significantly better, compared to the sick. Correlation tests showed that all dimensions of the quality of life were in close positive correlation with the general quality of life, with the level of satisfaction with the own health, with the self-assessed health, and with the responses given on other questions related to the social or health situation of the questioned.

CONCLUSION

The variation of the questionnaire, adapted to Hungarian conditions, proved to be suitable for testing the quality of life of persons with various demographical, social and health conditions, and for distinction between the healthy and the sick. The sheet, which can be filled in quickly and easily, enables the measurement of quality of life in the Hungarian population, and the comparison of that with international data.

Immunotoxicological investigation of subacute combined exposure with low doses of Pb, Hg and Cd in rats

Detectable interactions between NOEL (No Observed Effect Level) doses of Pb, Hg and Cd in general toxicological, hematological, and immune function parameters were investigated. The metals (Pb-acetate, 20 mg/kg; HgCl2, 0.40 mg/kg; CdCl2, 1.61 mg/kg) were combined. First, the rats received the combination Pb + Hg + Cd for 4 weeks per os. Significant difference vs. control was found only in the weight of lung and popliteal lymph node (PLN). The Pb + Hg and Pb + Cd combinations significantly decreased the PLN to 100 g body weight and PLN to brain weight ratio, and Pb+Hg also decreased the relative adrenal weight. After 12 weeks treatment with the same doses, effects on the thymus, kidney, and adrenal weights in the Pb + Hg, and thymus weight in the Pb + Cd, combination were seen. Pb + Cd also affected the white and red blood cell count and hematocrit. Combined with Hg or Cd, NOEL dose Pb showed toxicity, indicating that exposure limits may be inefficient in combined exposure situations.

The determinants of self-rated health among ethnic minorities in Hungary

BACKGROUND

The health status of a population is largely determined by the mutually interrelated factors of social and financial conditions, and by lifestyle, including health-related behaviour. The aim of the study was to investigate the factors influencing self-rated health among different ethnic minorities living in closed communities in the South-East Hungarian region.

METHODS

The cross-sectional survey was based on interviewer-administered questionnaires on socio-demographic variables, lifestyle and health status. In the study 100-120 persons were recruited from Serbian, Croatian, Romanian, German minorities and the Hungarian population. Univariate and multivariate logistic regression models were used.

RESULTS

In the univariate analyses, poor self-rated health correlated with all the factors examined except marital status. In the multivariate logistic regression model, poor health was found to be significantly associated with age, educational level, ethnicity, body mass index and chronic diseases. Poor self-rated health was observed in the Croatians and in the Hungarian control group.

CONCLUSION

In South-East Hungary, demographic parameters, especially being a member of a minority, and objective health status are highly important determinants of self-rated health. Several of the parameters studied in our survey indicated no effect or no special differences within the population of the region as concerns of self-rated health; certain other factors, however, proved to be special features for the studied ethnic minority, justifying the launching of target group-oriented health intervention programmes.

Alterations in the cortical and peripheral somatosensory evoked activity of rats treated with 3-nitropropionic acid

In this study, the action of 3-nitropropionic acid (3-NP) on the parameters of the cortical and peripheral evoked potentials was investigated in rats in different administration schemes (20 mg/kg i.p. during recording or 24 h before, and 5x 15 mg/kg daily 28 days before recording) to elucidate some neurophysiological effects of the substance. Responses in the somatosensory cortex and in the tail nerve, evoked by peripheral electric stimulation, were recorded in acute preparation under urethane anaesthesia. Amplitude, latency, and duration of the responses were measured. In rats treated 28 days before recording, latency of the cortical response was significantly (and the duration slightly) increased by 3-NP. The frequency dependence of the tail nerve response was more pronounced than that of the cortical response. After acute administration of 3-NP, the amplitude of the somatosensory evoked potential decreased. With double stimuli, the ratio of the amplitudes of the two responses (relative fatigue) was treatment-dependent. The relative refractory period of the tail nerve was altered both by acute and subacute 3-NP treatment. These results may be relevant in 3-NP based disease models but it needs further studies to find possible connections between the known biochemical effects of 3-NP and the functional neurotoxical changes described. The mode of evoked response analysis used is, theoretically, applicable for other neurotoxic effects and can be the base of development of functional biomarkers.

Effects of 3-nitropropionic acid in rats: general toxicity and functional neurotoxicity

3-Nitropropionic acid (3-NP) causes biochemical and morphological alterations in human and animal brain. Young adult male Wistar rats received 3-NP i. p. on five consecutive days and were investigated four weeks later (subacute treatment). Acute effects were investigated 24 h after one i. p. dose. Spontaneous or stimulus-evoked activity was recorded from cortical sensory foci, from subcortical nuclei and from the tail nerve, in urethane anesthesia. The subacutely treated rats were dissected and organ weights measured to study general toxic effects. After subacute treatment, decrease was seen in the theta, and increase in the beta-2 and gamma, band of the spontaneous activity, dissimilarly in the cortical vs. subcortical sites. Latency of the sensory evoked potentials increased in all sensory foci after subacute treatment. Following acute treatment, amplitude of the somatosensory evoked potential decreased. The weight of the thymus decreased significantly in the treated rats. Further studies could elucidate the link between biochemical effects of 3-NP and the observed functional neurotoxic changes.

Stimulus frequency dependence of the central and peripheral somatosensory evoked activity in rats treated with various pesticides

Rats were treated with a combination of insecticide agents in different timing schemes. In acute administration, 1/5 LD50 of the three insecticides: dimethoate, propoxur and cypermethrin, or their combination, was given once by gavage. In the developmental model, female rats received oral doses of 1/25 LD50 of the above insecticides in combination in three timing schemes including pregnancy and lactation. Responses in the somatosensory cortex and in the tail nerve, evoked by peripheral electric stimulation, were recorded in acute preparation under urethane anesthesia. It was tested whether the parameters of the cortical and peripheral evoked response are dependent on the frequency and whether this dependence is different in control and treated animals. The latency increase of the cortical responses with increasing stimulation frequency was significantly stronger in rats treated acutely with cypermethrin and the combination, and in rats receiving the combination during both intra- and extrauterine development. On the duration, the effects were less clear. Frequency dependent increase of the tail nerve action potential latency was significantly intensified by cypermethrin, and the amplitude decrease, by cypermethrin and dimethoate. Fatigue of this response during a stimulation series was also altered by the insecticides. Frequency dependence and fatigue possibly reflect the actual state of the nervous system and may have the potency to be developed to functional biomarkers.

Changes in the central nervous activity of rats treated with dimethoate in combination with other neurotoxicants in different phases of ontogenesis

Organophosphates are usually found in the environment with other pesticides and with pollutants of industrial origin can cause combined exposure involving unknown interactions between the agents. In this study, female Wistar rats were given 1/25 LD50 of dimethoate by gavage, combined with the same LD50 fractions of propoxur and cypermethrin or with arsenic (6.66 mg kg(-1)). The doses were given from day 5 to 15 of pregnancy, or that plus for the 4 weeks of lactation, or that plus 8 weeks for the male offspring after weaning. Control rats received distilled water. Electrophysiological recording was done when the male offspring reached 12 weeks of age. Spontaneous activity and evoked potentials from the somatosensory, visual and auditory cortex; and conduction velocity and absolute and relative refractory periods of the tail nerve were measured. The general trend was a shift of the spontaneous cortical activity to higher frequencies and increase in the evoked potential latency. The results showed that combined exposure to several environmental toxicants could be more harmful than the effects of each substance alone, indicating the importance of combination toxicology in modelling human effects. Furthermore, these results emphasize the importance of avoiding toxic exposures in pregnant and nursing women.

Combined effects of subchronic exposure to lead, mercury and alcohol on the spontaneous and evoked cortical activity in rats

The aim of this study was to investigate the effects of a combination of well-known neurotoxic heavy metals, lead and mercury, with ethanol. For 12 weeks, young adult male Wistar rats were given plain tap water or water containing 5% (v/v) ethanol to drink, and were treated with two doses of lead acetate or mercuric chloride by gavage. Accordingly, there was a water-drinking and an alcohol-drinking control group. After the treatment period, spontaneous and stimulus-evoked activity from the somatosensory, visual and auditory cortical areas was recorded. The frequency spectrum of the spontaneous activity, as well as latency and duration of the evoked potential were analysed. A shift in frequency was observed in the electrocorticogram, and lengthened latency and duration times in the evoked potentials. Alcohol seemed to influence the effect of the metals. Combined exposure to heavy metals and regular alcohol consumption may result in more severe central and/or peripheral neurotoxic outcomes.

Acute and subchronic effects of lead on the central and peripheral nervous systems in rats in combination with alcohol

Humans are exposed, either simultaneously or sequentially, to various chemicals, including the neurotoxicants lead and ethanol. The aim of the present work was to investigate the changes in the spontaneous cortical activity (electrocorticogram; ECoG) and in the stimulus-dependent evoked potentials (EPs) recorded from rats pre-treated with alcohol and treated with lead acutely (intraperitoneally) or subchronically (by gavage). The measured parameters were spectral composition of the ECoG, amplitude and the latency of the stimulus-evoked cortical potential, as well as compound action potential amplitude, conduction velocity, and relative and absolute refractory period in a peripheral nerve. With subchronic lead and alcohol treatment, significant increase in the frequency of spontaneous activity and slight decrease in the EP amplitude were seen. In acute administration, EP amplitude increased and conduction velocity of the tail nerve decreased significantly. Our results showed that, in a combined exposure situation which is likely to happen also in humans, the known effects of neurotoxic heavy metals can be more severe.

Functional neurotoxic effects in rats elicited by 3-nitropropionic acid in acute and subacute administration

Changes possibly induced by 3-NP in electrophysiological functional characteristics of the central nervous system are, in contrast to biochemical and morphological alterations, less well known. In this study, the usability of a standard neurophysiological investigation system to detect functional changes caused by 3-NP administration in rats was studied. In subacute treatment, 10 or 15mg/kg 3-NP was given i.p. on five consecutive days to groups of 10 rats and the effects were checked 4 weeks later. Acutely treated rats received 20mg/kg i.p. after several control records. For recording, the animals' left hemisphere was exposed in urethane anesthesia. Silver electrodes were placed on the cortical sensory foci and tungsten needles in the subcortical (caudatum, globus pallidus) recording sites. Spontaneous electrical activity, as well as somatosensory, visual and auditory evoked potentials, were recorded. Following subacute treatment, the slowest (theta) and fastest (beta2 and gamma) frequencies of the spontaneous activity were changed, differently in the cortical versus subcortical sites. In the sensory evoked potentials after subacute treatment, an increase of the latency was seen in all sensory areas. In the acutely treated animals, the amplitude of the somatosensory evoked potential decreased after giving 3-NP. With double stimuli, the relation of the two responses was treatment- and interval-dependent. Understanding the mechanism of these effects may widen the knowledge base for using 3-NP in disease models.

Behavioral and neurotoxicological effects of subchronic manganese exposure in rats

In male Wistar rats, behavioral and electrophysiological investigations, and blood and brain manganese level determinations, were performed; during 10 weeks treatment with low-dose manganese chloride and a 12 weeks post-treatment period. Three groups of 16 animals each received daily doses of 14.84 and 59.36mg/kg b.w. MnCl(2) (control: distilled water) via gavage. During treatment period, Mn accumulation was seen first in the blood, then in the brain samples of the high-dose animals. Short- and long-term spatial memory performance of the treated animals decreased, spontaneous open field activity (OF) was reduced. The number of acoustic startle responses (ASR), and the pre-pulse inhibition (PPI) of these, diminished. In the cortical and hippocampal spontaneous activity, power spectrum was shifted to higher frequencies. The latency of the sensory evoked potentials increased, and their duration, decreased. By the end of the post-treatment period, Mn levels returned to the control in all samples. The impairment of long-term spatial memory remained, as did the number of acoustic startle responses. Pre-pulse inhibition, however, returned to the pre-treatment levels. The changes of the open field activity disappeared but a residual effect could be revealed by administration of d-amphetamine. The electrophysiological effects were partially reversed. By applying a complex set of methods, it was possible to obtain new data for a better-based relationship between the known effects of Mn at neuronal level and the behavioral and electrophysiological outcomes of Mn exposure.

Effect of acute administration of certain heavy metals and their combinations on the spontaneous and evoked cortical activity in rats

The aim of this study was to see the effect of acutely administered inorganic lead, mercury, manganese, and their combinations, on the electrical activity in the somatosensory system of rats. Male Wistar rats were anaesthetised with urethane, the head was fixed in a stereotaxic frame and the left hemisphere was exposed. Weak electric shocks to the whiskers and the tail served as stimuli. Spontaneous and stimulus-evoked activity was recorded from the primary projection area of the whiskers and the tail. After an hour of control recording, one of the following was given to the rat i.p.: 1000mg/kg Pb(2+), 7mg/kg Hg(2+), 50mg/kg Mn(2+), 500mg/kg Pb(2+)+25mg/kg Mn(2+), or 500mg/kg Pb(2+)+3.5mg/kg Hg(2+). Lead caused a massive increase in the cortical response amplitude, starting immediately after administration and developing in the next 40-50min. Latency showed a minimal increase. The spontaneous activity was moderately shifted to lower frequencies. The effect of Hg(2+) on the response amplitude and on the ECoG was similar but stronger than that of Pb(2+). The effect of Mn(2+) on the evoked activity was marked but less strong than with Pb(2+). The ECoG shift was moderate. With Hg(2+) and Mn(2+), the response amplitude showed first a decrease than an increase. The effect of the Pb(2+)+Mn(2+) combination on the activities was not additive but the correlation between the alteration of the ECoG and the evoked potential was stronger than with any of the metals alone. With Pb(2+)+Hg(2+), the effect of Pb(2+) dominated on the evoked and that of Hg(2+) on the spontaneous activity. In the peripheral nerve, action potential amplitude and conduction velocity were decreased. These alterations of the spontaneous and stimulus-evoked cortical activity probably reflected a specific action of the heavy metals on the nervous activity.

Behavioral and neurotoxic effects seen during and after subchronic exposure of rats to organic mercury

Young adult male Wistar rats (24/group) were treated for 5 weeks with methyl mercury(II)chloride (corresponding to 0.5 and 2.0mgHg°/kg b.w., control: distilled water) by gavage, followed by a 19 weeks post-treatment period. Spontaneous motility, psychomotor performance and sensorimotor gating was repeatedly tested, electrophysiological recordings done, in the rats throughout the whole experiment. Decreased horizontal open field activity, reduced number of "noise positive" startle responses, as well as increase of startle response onset latency and peak time, and decrease of peak amplitude, was seen in the treated animals. Most changes disappeared in the post-treatment period. In the spontaneous cortical and hippocampal activity, altered distribution of the frequency bands was seen after 5 weeks of treatment but not at the end of the post-treatment period. Hippocampal population spikes in the treated animals were depressed and showed less potentiation, which effect was still present 19 weeks after finishing the treatment. The duration of the sensory cortical evoked potentials was shorter than in the controls. In the treated rats, tyrosine hydroxylase-immunoreactive boutons in the substantia nigra pars reticulata were shrunk; blood and brain Hg levels were significantly higher and decreased only slowly. Considering the continuous presence of low levels of mercurials in the human environment, effects of this kind may be supposed as the background of some human neurobehavioral abnormalities.

Effect of folic acid supplementation on aluminum accumulation in rats

OBJECTIVE

Exposure to many xenobiotics may cause depletion of folic acid (folate), which is an essential vitamin for humans. Replacement of folate can be effective in protection against some diseases and in partial or total prevention of adverse effects related to xenobiotics. Aluminum (Al) is the most widely distributed metal in the outer crust of the earth. Its toxicity in humans is well known. However, there is no evidence that folate can decrease accumulation of Al to which humans can be exposed in many ways. The aim of the present study was to quantify organ Al accumulation and to evaluate whether there is any protective (or reductive) effect of folic acid on Al accumulation.

METHODS

Male Wistar rats were assigned oral Al chloride (200 mg x kg(-1) x d(-1), n = 10, group 1) alone or in combination with folic acid (20 mg x kg(-1) x d(-1), n = 10, group 2) for 8 wk. At the end of the period, bone, kidney, brain, and blood samples were collected, and Al concentrations were determined by electrothermal atomic absorption spectrophotometry.

RESULTS

Mean values of Al in the tissue samples from group 1 were higher than those from group 2 (all P < 0.05). No difference was observed in serum Al levels between groups (P > 0.05).

CONCLUSION

These results suggest that folate supplementation might be useful to decrease Al accumulation in its main target organs, i.e., bone, kidney, and brain.

Subchronic mercury treatment of rats in different phases of ontogenesis: functional effects on the central and peripheral nervous system

Electrophysiological changes caused by inorganic mercury administration during the pre- and/or postnatal development were studied. Pregnant female Wistar rats were treated, by gavage, with 0.4, 0.8 or 1.6 mg/kg mercury (HgCl2 diluted in distilled water): 1/ from day 5 to 15 during pregnancy (P protocol); 2/ from day 5 to 15 of pregnancy+for 4 weeks of lactation (P+L protocol); 3/ from day 5 to 15 of pregnancy+for 4 weeks of lactation, and the offspring were further treated for 8 weeks post-weaning (P+L+P protocol). Electrophysiological parameters (electrocorticogram, cortical evoked potentials, conduction velocity and refractory periods of peripheral nerve) of the male offspring from dams in the groups treated according to the above protocols were investigated at the age of 12 weeks. The rats' spontaneous and evoked electrophysiological activity underwent dose- and treatment-dependent changes following the treatment (increased frequency of spontaneous activity, lengthened latencies and duration of evoked potentials, lower conduction velocity of the peripheral nerve, etc.). In the same rats, however, the treatment failed to cause major signs of general intoxication. The results emphasize the functional neurotoxic risk arising from the continuous presence of inorganic mercury in the human environment, and point to possible use of early functional changes for monitoring the effects of mercury.

Changes in the spontaneous and stimulus-evoked activity in the somatosensory cortex of rats on acute manganese administration

In this work, acute effects of inorganic manganese exposure on nervous electrical activity of rats were investigated. Young adult male Wistar rats were prepared for recording in anaesthesia and spontaneous cortical as well as stimulus-evoked cortical and peripheral nervous activity was recorded before and after i.p. administration of 25 and 50 mg/kg Mn2+. The alterations found resulted possibly from several known neuronal effects of manganese. The frequency shift of spontaneous cortical activity, and increased latency and decreased amplitude of the peripheral nerve action potential, were probably due to the Mn(2+)-induced impairment of the mitochondria, whereas the increased amplitude of the evoked cortical response, to the effect on glutamatergic transmission.

Simultaneous changes of the spontaneous and stimulus-evoked cortical activity in rats acutely treated with mercuric chloride

In earlier studies of our laboratory and in several other reports, alterations in the electrical activity of the cortex of experimental animals on subchronic mercury (Hg) administration were described. In the present work, simultaneous changes in the spontaneous and stimulus-evoked cortical activity elicited by acute administration of inorganic Hg were evaluated with the aim of finding any correlation of the two, possibly giving insight into the mechanism of the alterations. In young adult male Wistar rats, spontaneous cortical, as well as stimulus-evoked cortical and peripheral nervous activity was recorded, before and after acute administration of 3.5 and 7.0 mg/kg Hg2+ ip. The effects of Hg2+ appeared within 10 min and most became significant over 3 h. On the cortex, slowed spontaneous activity, as well as increased amplitude and latency of the evoked potentials (EPs) was seen, and in the periphery, decreased nerve conduction velocity. These alterations seemed to be consistent with a separate cortical and peripheral axonal effect of Hg.

A study on electrophysiological effects of subchronic cadmium treatment in rats

Male Wistar rats were treated for 4, 8 and 12 weeks with 3.5, 7.0 or 14.0 mg/kg cadmium (in the form of cadmium chloride) by gavage. Changes induced in certain electrophysiological parameters-electrocorticogram frequency; latency and duration of cortical sensory evoked potentials; conduction velocity and relative and absolute refractory periods of a peripheral nerve-were analyzed. On the electrocorticogram, increased frequency was seen. Lengthened latency and duration of the cortical evoked potentials, as well as lowered conduction velocity and increased refractory periods in the peripheral nerve, were observed. These changes seemed to increase with the dose and the treatment time and were statistically significant mainly in the highest dose groups following 12 weeks of treatment. The results show that subchronic, low-level exposure by cadmium affects the rat's spontaneous and evoked bioelectric activity and point at the possible consequences in exposed humans.

A study on behavioral, neurotoxicological, and immunotoxicological effects of subchronic arsenic treatment in rats

Male Wistar rats were treated for 4, 8, and 12 wk with 3.33, 6.66, 13.3, or 26.6 mg/kg of inorganic arsenic (NaAsO(2)) per os by gavage. Changes in behavioral and electrophysiological parameters (spontaneous open-field exploration; electrocorticogram mean frequency and power spectrum; latency and duration of somatosensory, visual, and auditory evoked potentials; conduction velocity; and relative and absolute refractory period of a peripheral nerve) were determined. Treated rats exhibited hypoactivity of horizontal ambulation in the open field and showed depressed rates of grooming. The electrophysiological data, recorded from anesthetized rats, did not show any significant dose- and time-dependent changes. Changes in humoral immune response, tested after 4 wk of treatment, were not marked. The weight of organs responsible for immune response (thymus, spleen, adrenals), was significantly reduced, as were delayed-type hypersensitivity (DTH) reaction and mean cell volume (MCV) of red blood cells a hematological parameter. Plaque-forming cell (PFC) assay proved to be insensitive in this short-time exposure. These results suggest that subchronic low-level exposure to arsenic can affect immune responses and/or spontaneous behavior of rats.

Use of echocardiography among patients with heart failure: practice variations in Hungarian hospitals

OBJECTIVE

To evaluate some factors, such as demographic factors, disease severity, dissemination of practice guidelines, and hospitals providing medical care, influencing the use of echocardiography among patients with congestive heart failure.

DESIGN

A 'before-after' controlled epidemiological study based on hospital documentation.

SETTING AND PARTICIPANTS

A total of 1222 admitted patients with a diagnosis of chronic heart failure from six voluntarily participating hospitals representing each level of in-patient care in Hungary.

INTERVENTIONS

Implementation of clinical practice guidelines about heart failure developed by the US Agency for Health Care Policy and Research.

RESULTS

The echocardiography was performed in slightly more than 50% of all cases in the total. The use of echocardiography was different according to age, sex, and hospitals, but no significant difference was found in disease severity and between the two periods of time (before and after the dissemination of the guidelines).

CONCLUSIONS

This study reveals the existing differences in the use of echocardiography and the lack of essential changes after the dissemination of the guidelines. The distribution and implementation of guidelines needs further investigation.

A study on geno- and immunotoxicological effects of subacute propoxur and pirimicarb exposure in rats

A 28-day oral exposure with 8.51, 3.40, and 0.851 mg/kg propoxur (PR) and 4.67, 1.87, and 0.467 mg/kg pirimicarb (PI) was performed in male Wistar rats, and the occurrence of numerical and structural chromosome aberrations and the changes in certain immune function parameters (plaque-forming cell (PFC) assay, delayed-type hypersensitivity reaction) and in some basic toxicological (body weight gain and weights of brain, thymus, lung, heart, liver, spleen, kidneys, adrenals, and popliteal lymph node) and hematological (white blood cells, red blood cells, hematocrit (Ht), mean cell volume of red blood cells (MCV) cell content of the femoral bone marrow) parameters were investigated. The high dose of PR increased the relative liver weight and the cell content of femoral bone marrow, and all three doses increased Ht and MCV. The applied doses of PI decreased the relative adrenal weight in a dose-dependent manner, and its highest dose increased the relative liver weight. Among the immune function parameters tested, PFC content of the spleen was decreased by high-dose PR and elevated by high-dose PI, whereas the maximum and the time course of the delayed-type hypersensitivity reaction showed no changes in this dose range. In the genotoxicological investigations only the high PR dose increased the number of numerical, but not the structural, chromosome aberrations. In addition to the changes in relative adrenal weight following PI treatment, the PFC assay showed the highest sensitivity for detection of the 4-week exposure with these carbamates. On the basis of our results, the immunotoxicological approach seems to have the same (PR) or higher (PI) sensitivity in early detection of the repeated low-dose exposure by these carbamates compared to the genotoxicological approach.

Behavioural effects of subchronic lead treatment in combination with ethanol in rats

The effect of lead acetate administration during perinatal (1. prenatal, 2. prenatal and suckling period, 3. prenatal + suckling period + 4 weeks after weaning) development in combination with ethanol was investigated in Wistar rats at the age of 12 weeks on open-field behaviour and auditory startle response. Lead intoxication has on the investigated behavioural parameters the most pronouncing effect when applied during the days 5-15 of pregnancy.

Small subchronic doses of the pesticide dimethoate and/or cadmium and lead treatment causes disturbances in the chromosomes of young rats

Small doses of Dimethoate (DM) and cadmium (Cd) which in themselves proved to be harmless in causing chromosome aberrations, potentiate each other's toxic effect concerning both numerical and structural aberrations caused in rat bone marrow cells. The toxic effect of lead (Pb) was not enhanced by DM.

Electrophysiological biomarkers of an organophosphorous pesticide, dichlorvos

The correlations between the relatively low level, chronic dichlorvos (DDVP) treatment and the early electrophysiological changes were investigated in three series of experiments. In the first series, male Wistar rats were orally given daily by gavage 0.98, 1.96 and 3.92 mg/kg of DDVP for 4, 8, or 12 weeks, and recordings were made at the end of each period. In the second one, the male and female rats of three consecutive generations were treated with the same doses, the investigated parameters were recorded at the age of 12 weeks of the male animals. In the third experiment, the doses were administered in different stages of development: during pregnancy, pregnancy + lactation, pregnancy + lactation + postweaning, and the electrophysiological markers were recorded also at the age of 12 weeks of male offspring. The analyzed elecrophysiological parameters were: electrocorticogram, sensoric cortical evoked potentials, conduction velocity and refractory periods of peripheral nerve. The data showed that the relatively low level dichlorvos exposure caused dose-, duration-, generation-, developmental stage-dependent and partly significant alterations in all the investigated electrophysiological parameters. The analyzed functional parameters proved to be sensitive biomarkers of the exposure as they were changed by the lower doses, while the brain cholinesterase activity was considerably inhibited only in the groups given the highest dose.

Epidemiological investigations and experimental model studies on exposure of pesticides

Authors carried on epidemiological examinations on plant protection workers to find early symptoms (biomarkers) of moderate contamination by pesticides. Measurement of changes in cholinesterase and gamma glutamyltransferase enzyme activity did not reveal that people were affected. Determination of chromosome abnormalities from peripheral lymphocytes disclosed numerical aberrations at an early stage and lasted after cessation of work for several months. There were differences in the results among different groups of plant protection workers, as well as among those working in open field or in glasshouses. Women, who carried out horticultural work in glasshouses after spraying showed some chromosome abnormalities too. Experimental rats treated chronically with organophosphates exhibited changes in spontaneous and evoked brain electrical activity (ECoG). Concerning the peripheral nervous activity, conduction velocity became slower, absolute and relative refractory periods became longer. These proved sensitive biomarkers too, which could be used in early detection of contamination.

Developmental neurotoxicological effects of lead and dimethoate in animal experiments

Neurophysiological changes caused by parallel treatment with inorganic lead and dimethoate (a combination of possible health risk at population level) were investigated in different phases of the ontogenesis. Wistar rats were treated by gavage with lead (80.0 or 320.0 mg/kg); with dimethoate (7.0 or 28.0 mg/kg), or with their combination on days 5-15 of pregnancy, days 5-15 of pregnancy + days 2-28 of lactation (females of P generation), or days 5-15 of pregnancy + days 2-28 of lactation (females of P generation) + 8 weeks after weaning (males of F1 generation). Electrophysiological parameters (electrocorticogram, cortical evoked potentials) of the F1 male rats in the above groups were investigated at the age of 12 weeks. Both spontaneous and evoked electrophysiological phenomena showed dose-, treatment- and combination-dependent changes (e.g. significantly decreased mean amplitude and increased frequency of the electrocorticogram, lengthened latency and duration of the somatosensory, visual and auditory evoked potentials) which seemed to be more pronounced in the groups treated with the combination of lead and dimethoate than in the groups given lead or dimethoate alone. The results indicate that a simultaneous, pre- and postnatal exposure to the neurotoxicants, lead and dimethoate, considerably altered the functioning of the central nervous system.

Experimental model studies of pesticide exposure

The neurotoxic effects of Dimethoate (Dim), Dichlorvos (DDVP) and Methyl-Parathion (MP) respectively were investigated on the central nervous system (CNS) and peripheral nervous system (PNS) of rats after different treatment schedules at the macro and single unit cell level. At the macro investigations 1/25, 1/50 and 1/100 of the respective LD50 values of each pesticide were administered to different groups by gavage daily in the following programs: Pregnancy variation (P) to females from 5th to 15th days of pregnancy; Pregnancy and lactation variation (P+L): to females as above and during lactation for 4 weeks; Pregnancy+lactation+post weaning variation (P+L+P) as above plus to the young male rats (F1 generation) up to 8 weeks. Neurotoxicological investigations were conducted on the F1 rats at the age of 12 weeks. Spontaneous electrocorticograms (ECoG) were recorded on the anesthetized rats from the somatosensory, visual and auditory cortex. Cortical evoked potentials (EP) were recorded from the same areas subsequently. Conduction velocity and refractory periods of the tail nerve was investigated. Treatment by Dim, DDVP and MP during P and P+L of the mothers did not influence the bioelectric activity of the offsprings significantly. The same treatment by the P+L+P programme, resulted in significant changes. Frequency of the spontaneous ECoG waves grew significantly in all dose groups of P+L+P group. Latency time become shorter after somatosensory. light or acoustic stimuli respectively on one hand and the beginning of the of answer of these by the evoked potential (EP) waves on the other hand. Conduction velocity of the tail nerve diminished, refractory periods grew dose dependently and significantly at the P+L+P programs with all the three pesticides. Cortical single unit activity was studied after the i.p administration of 1/5 LD50 of the three organophosphates (OP). The decrease of the firing frequencies was observed. The amplitude of the hippocampal population spikes increased. The changes observed in these studies point toward a higher excitation state of the CNS and a disturbed conduction of the nervous impulses of the peripheral nerves. These results could be taken into consideration when deciding on human contaminations by OP-s.

Behavioural and neurotoxicological changes caused by cadmium treatment of rats during development

Behavioural and electrophysiological changes caused by inorganic cadmium were investigated in the offspring of female Wistar rats. Dams were given 3.5, 7.0 or 14.0 mg kg(-1) cadmium (cadmium chloride dissolved in distilled water) in three different treatment regimes: days 5-15 of pregnancy; days 5-15 of pregnancy + 4 weeks of lactation; days 5-15 of pregnancy + 4 weeks of lactation followed by the same oral treatment of male rats of the F1 generation for 8 weeks. The behavioural (open-field exploration) and electrophysiological (electrocorticogram, cortical evoked potentials, conduction velocity and refractory periods of a peripheral nerve) parameters of F1 male rats exposed by various treatments were investigated at the age of 12 weeks. It was found that cadmium dose and treatment time dependently altered the spontaneous and evoked electrophysiological functions (e.g. increased the frequency of the electrocorticogram, lengthened the latency and duration of evoked potentials, etc.). Interestingly, only the combination of treatment during prenatal development and the 4-week suckling period resulted in a significant dose-dependent decrease of horizontal and vertical exploratory activity and a significantly lower exploration frequency of the open-field centre. The results showed that low-level pre- and postnatal inorganic cadmium exposure affects the bioelectrical and higher order functions of the nervous system. In the case of human populations, a similar prolonged exposure might be just as harmful.

Behavioural and functional neurotoxicological changes caused by cadmium in a three-generational study in rats

1. Three consecutive generations of Wistar rats were orally treated by gavage with 3.5, 7.0 or 14.0 mg/kg cadmium (in form of cadmium chloride diluted in distilled water) over the period of pregnancy, lactation and 8 weeks after weaning. 2. Behavioural (open field behaviour) and electrophysiological (spontaneous and evoked cortical activity, etc.) parameters of male rats from each generation were investigated at the age of 12 weeks. 3. The main behavioural outcomes were change in vertical exploration activity (rearing) and increased exploration of an open field centre. The spontaneous and evoked electrophysiological variables showed dose- and generation-dependent changes (increased frequencies in the electrocorticogram, lengthened latency and duration of evoked potentials, etc.) signalling a change in neural functions. 4. The data show that low-level, multigeneration exposure to inorganic cadmium can affect functions of the nervous system. This suggests that cadmium exposed human populations may be at risk of developing nervous system disorders.

Effect of subchronic mercury exposure on electrocorticogram of rats

Mercury is a neurotoxic compound causing irreversible disorders of the central and peripheral nervous system. In some of the previous human and experimental studies mercury also affected some functional neurological parameters such as EEG, and cortical evoked potentials. In the present study, the effect of subchronic (4, 8, and 12 weeks) relatively low-level (0.4, 0.8, and 1.6 mg/kg mercury in form of HgCl2, per os by gavage) treatment on the basic cortical activity was investigated. Certain parameters of electrocorticogram (ECoG) recorded simultaneously from the primary somatosensory, visual and auditory centres were analyzed. The results showed that mercury had a dose- and time-dependent effect on the examined ECoG parameters, and the changes became significant by the end of the experiment of week 12.

Electrocorticogram changes caused by subchronic lead treatment of rats

Male Wistar rats were treated per os through gavage for 4, 8 and 12 weeks by 80.0, 160.0 and 320.0 mg/kg lead in form of lead acetate. The changes of certain parameters (mean frequency, mean amplitude, ECoG index-the ratio of the slow and fast bands, power spectrum of the frequency bands) of the electrocorticogram (ECoG) recorded from the primary somatosensory, visual and auditory centres of anaesthetized rats were analysed. The data show that all investigated parameters had dose- and time-dependent changes: increased mean frequencies accompanied by decreased mean amplitudes and ECoG-indices. These changes were significant only at the highest, or at the two higher dose groups by the end of the experiment. The data suggest that subchronic, low-level exposure of lead can affect the integrated electrophysiological function of the brain.

Opposite short-term changes induced by an organophosphate in cortical and hippocampal evoked activity

Organophosphates are the most widely used pesticides throughout the world. The considerable amount brought out to the environment poses a risk on the whole population. As organophosphates are neurotoxic substances and their residues can persist in the environment for several weeks, their influence on the nervous system of humans and animals is of principal interest. In the present study, we investigated the alterations induced by dichlorvos, a common pesticide substance, in parameters of somatosensory evoked potentials and hippocampal evoked population spikes of rats. The changes of the cortical vs. hippocampal evoked responses were opposite and only hippocampal effects could be directly explained through an increased cholinergic activity.

Life-time exposure to dichlorvos affects behaviour of mature rats

Wistar rats were exposed to dichlorvos [CAS number 62737]. Doses were 1/25; 1/50; and 1/100 LD50, that is 3.88; 1.94; 1.46; and 0.97 mg kg-1 DDVP, respectively, throughout gestation (GD1-birth) and during suckling via oral dosing to the dams, and then via the same doses by gavage for the rest of their lives. The offspring were tested in an open field (OF), a multiple T-maze, and in a 'novelty-induced-grooming' test to assess behavioural competence as adults. Dose-related increases in running time and incorrect choices in the maze were observed during the first 2 weeks of a 3-week study at 9-11 weeks of age. Horizontal activity was increased, vertical activity decreased, and defecation decreased in the OF at 9-12 weeks of age; these changes were again dose-related. Sleep was also affected at 12 weeks of age. AChE activity in the brain and in blood at sacrifice was roughly 40% to 65% of control, again reflecting the doses administered. The significantly changed behavioural profile of DDVP treated rats may serve as a useful biomarker to judge functional damage of CNS properties.