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Biomedical subjects

M Horvat

Publications and source records attributed to M Horvat.

At least 37 records · Page 2Linked to original sources
PubMed2000

Mercury, selenium, and cadmium in human autopsy samples from Idrija residents and mercury mine workers.

Total Hg and Se concentrations were determined in autopsy samples of retired Idrija mercury mine workers, Idrija residents living in a Hg-contaminated environment, and a control group with no known Hg exposure from the environment. In selected samples we also checked the presence of MeHg. The highest Hg concentrations were found in endocrine glands and kidney cortex, regardless of the group. MeHg contributed only to a negligible degree to the total mercury concentrations in all analyzed samples. In the Hg-exposed groups the coaccumulation and retention of mercury and selenium was confirmed. Selenium coaccumulation with a Hg/Se molar ratio near 1 or higher was notable only in those tissue samples (thyroid, pituitary, kidney cortex, nucleus dentatus) where the mercury concentrations were >1 microg/g. After tissue separation of such samples the majority of these elements were found in the cell pellet. Because the general population is continuously exposed to Cd and possibly also to Pb from water, food, and/or air, in some samples the levels of these elements were also followed. In all examined control tissue samples the average values of Cd (kidney cortex, thyroid, hippocampus, cortex cerebellum, nucleus dentatus) and Pb (thyroid, hippocampus) exceeded the average values of Hg. Cd concentrations were the highest, particularly in kidney cortex and thyroids (microg/g), but no relationship between Cd and Se concentration was evident at the tissue level. Regarding the results in the control group, it is debatable which element is the more hazardous for the general population as concerns neurotoxicity.

Adult↗
PubMed2000

A methodological study of mercury speciation using dogfish liver CRM (DOLT-2).

The purpose of the study was to optimise analytical methods for determination of the chemical speciation of mercury in studies of protective mechanisms of selenium. Optimisation of the methods was performed using CRM DOLT-2 (Dogfish liver), both in its original form and after separation of various fractions. The sample was homogenised with 10 mM Tris-HCl buffer (pH 7.6) and ultracentrifuged. The soluble phase obtained was applied to a size exclusion chromatography column (Sephadex G-75 column) for separation of various protein fractions. Total mercury (total Hg), monomethyl mercury (MeHg) and selenium (Se) were determined in whole dogfish liver tissue and its soluble and insoluble phases (pellet). Different approaches for determination of total Hg and MeHg were compared. Simultaneous determination of MeHg and inorganic mercury (Hg2+) was based on alkaline dissolution and/or acid leaching, followed by ethylation, room temperature precollection, isothermal gas chromatography (GC), pyrolysis and detection with cold vapour atomic fluorescence spectrometry (CVAFS). The sum of MeHg and Hg2+ was compared to total Hg results obtained by acid digestion and CVAAS detection. The accuracy of MeHg determination was checked by its determination using acid leaching at room temperature, solvent extraction, back extraction into Milli-Q water, ethylation, GC and CVAFS detection. For the insoluble phase it is recommended to use solvent extraction for MeHg and acid digestion CVAAS for total Hg. For determination of MeHg and Hg2+ in the lyophilised sample and water soluble fractions containing low concentrations of mercury species, the simultaneous measurement of MeHg and Hg2+ after alkaline dissolution is the most appropriate method.

Animals↗
PubMed2000

Certification of trace and major elements and methylmercury concentrations in a macroalgae (Fucus sp.) reference material, IAEA-140.

A marine reference material, IAEA-140, prepared with a macroalgae (Fucus sp.) was recently produced by the International Atomic Energy Agency and certified for trace and major elements and for methylmercury (MeHg). Certification of this material was achieved as an outcome of an international analytical intercomparison study which resulted in 116 independent sets of results reported by participants from 54 countries. The statistical evaluation of the collected data and the criteria used for assignment of the mean and uncertainty values are described. The analysis of data allowed to certify concentration values for 24 elements and MeHg, and to provide information values for another 10 elements. Regarding the elements which could be given certified values, between two and eight different instrumental methods were used to measure metal concentrations, and four independent analytical procedures were used to measure MeHg concentrations. In order to assess the results of the certification procedure, a comparison was made between the certified values obtained from the world-wide intercomparison results and the values obtained from a small subgroup of well-qualified laboratories. The means and 95% confidence intervals for reference values obtained by the two methods are similar for most elements showing that the usual method of certification used by the IAEA, based on large groups of participants, is indeed pertinent.

Environmental Pollutants↗
PubMed2000

Determination of mercury in crude oil by in-situ thermal decomposition using a simple lab built system.

A simple system based on thermal decomposition for the one step determination of mercury has been built. This system was applied to the analysis of crude oil and related products. Samples were directly introduced into the system without the use of chemicals and digestion procedures. After 4 min, matrices and mercury compounds were decomposed, and elemental mercury was collected on a gold sand trap, and then detected by atomic fluorescence spectroscopy (AFS). In principle, any sample can be analyzed by this method provided the sample can be introduced into the system quantitatively. The method detection limit was approximately 0.2 ng/g for 0.04 g of crude oil introduced to the system. Various other samples including, biological, environmental, and general merchandise have been analyzed. Results obtained have been compared with established traditional methods including radiochemical neutron activation analysis (RNAA). Good agreement of results between methods was found. Recoveries were close to 100% for certified reference materials. Results were independent of mercury species and sample types.

Journal Article↗
PubMed2000

Mercury and other elements in lichens near the INA Naftaplin gas treatment plant, Molve, Croatia.

This paper describes the use of epiphytic lichens as bioindicators for spatial monitoring of mercury and other elements in air near the natural gas treatment facilities at Molve, Croatia. It is well known that at this location the concentration of mercury in natural gas is very high and therefore it has to be removed from natural gas before further processing in order to prevent technological and environmental problems. In order to monitor the efficiency of an industrial facility for removal of mercury from natural gas, mercury measurements in air and lichens were performed during 9 months in 1997/1998. In situ lichens Parmelia sulcata, Xantoria parientina and Hypogymnia physodes and transplanted lichen species Hypogymnia physodes were used. A good correlation between mercury concentrations in air and lichens was found. The concentrations of barium and bromium were also significantly elevated in transplanted lichens, most probably related to technological process at the gas treatment plant and/or other geological factors. It was confirmed that lichens can successfully be used as bioindicators, provided a careful experiment is designed, particularly the amount of lichens transplanted, the duration of exposure and the initial levels and homogeneity of transplanted lichens.

Croatia↗
PubMed2000

Acute isoniazid neurotoxicity during preventive therapy.

OBJECTIVE: To describe rare side effects of treatment with isoniazid. DESIGN: Descriptive case report. SETTING: Medical intensive care unit in a university medical center. PATIENT: A 14-yr old previously healthy girl receiving preventive isoniazid therapy who suddenly developed generalized tonic-clonic seizures and coma. INTERVENTIONS: Patient was sedated and mechanically ventilated. She also received pyridoxine intravenously. MEASUREMENTS AND MAIN RESULTS: An isoniazid overdose was not confirmed. Computed tomography of the brain and electroencephalogram revealed nothing abnormal. Seizures gradually disappeared within 2 hrs after sedation and treatment with pyridoxine. The patient was discharged on day 14 without consequences and has been well for 10 mos. No seizures reappeared after isoniazid was discontinued. CONCLUSIONS: We caution against possible isoniazid neurotoxicity in healthy individuals using recommended preventive doses.

Acute Disease↗
PubMed1999

Mercury in contaminated coastal environments; a case study: the Gulf of Trieste.

Some general facts, uncertainties and gaps in current knowledge of Hg cycling in coastal and oceanic environments are given. As a case study the Gulf of Trieste is chosen. The Gulf is subject to substantial Hg pollution, originating from the Soca river, that drains the cinnabar deposits of the world's second largest Hg mining area, Idrija, Slovenia. The Gulf belongs to one of the most polluted areas in the Mediterranean. Apart from Hg problems, the Gulf is also a subject to industrial and sewage pollution. Due to deteriorating water quality in the Gulf there is a great concern that Hg can be remobilized from sediments to the water column as well as enhance methylation rates which may consequently increase already elevated Hg levels in aquatic organisms. The paper presents data from a recent study which aims to assess the extent of contamination of the Gulf of Trieste after the closure of the Hg mine. Mercury and methylmercury were measured in various environmental compartments (estuarine and marine waters, sediments, and organisms) during the period 1995-1997. Data obtained show that even 10 years after closure of the Hg mine, Hg concentrations in river sediments and water are still very high and did not show the expected decrease of Hg in the Gulf of Trieste. A provisional annual mercury mass balance was established for the Gulf of Trieste showing that the major source of inorganic mercury is still the River Soca (Isonzo) while the major source of methylmercury is the bottom sediment of the Gulf.

Geologic Sediments↗
PubMed1999

The IAEA worldwide intercomparison exercises (1990-1997): determination of trace elements in marine sediments and biological samples.

Four major worldwide intercomparison exercises for the determination of trace elements in various environmental matrices were completed by the IAEA Marine Environment Laboratory since 1990: SD-M-2/TM, deep sea marine sediment; IAEA-350, tuna fish homogenate; IAEA-356, contaminated coastal sediment and IAEA-140, sea plant (Fucus sp.). These intercomparison exercises aim at enabling individual laboratories to monitor their performance. The results of these exercises allowed us to make an overall evaluation of the quality of data provided for environmental assessment and to identify the trends of analytical performance in the determination of trace elements over the years. The number of participants in each exercise varied between 68 and 130, and permits statistical evaluation of the performance for a number of elements. For each intercomparison exercise, the performance of the participant laboratories was assessed by comparing reported results with established reference values calculating 'Z-scores'. The results show that for each sample matrix, the values reported by some laboratories were far from satisfactory in the earlier exercises, in particular for Cd, Cr and Pb. Nevertheless, over time, a general improvement of performance can clearly be seen for all elements. Moreover, there was a noticeable increase in the number of laboratories with good performance in the two most recent exercises, observed both for biological and for sediment matrices. However, the determination of trace elements such as Cd, Cr, Pb and Hg in low level environmental samples still remains a major challenge to the analysts. For this reason and in order to assess the current performance of laboratories for low environmental levels of contaminants, the future intercomparison exercises will concentrate on low level sediment and fish samples.

Animals↗
PubMed1999

Current status and future needs for biological and environmental reference materials certified for methylmercury compounds.

A good quality control/quality assurance programme should be implemented in all environmental or health related studies on mercury and its organic compounds, particularly, for monomethylmercury (MeHg) which is the most toxic mercury compound. This can be achieved initially by analysing suitable certified reference materials (CRMs), which are available from various producers such as the National Institute of Standards and Technology (NIST) from USA, National Institute of Environmental Studies (NIES), National Research Council of Canada (NRCC), Standards, Measurements and Testing programme (SM&T) of the European Commission, and the International Atomic Energy Agency (IAEA). It is well understood that these materials are not covering present needs, as most of them are of the marine origin, while many laboratories are conducting research and monitoring in terrestrial ecosystems and fresh water environment. In addition, CRMs for human exposure assessment, such as blood, urine, and hair at several levels of concentrations are still lacking. Therefore, many other actions should be undertaken to achieve, improve and/or maintain quality of data, including participation in interlaboratory studies, proficiency testing and production of laboratory reference materials. A review of these actions has shown that MeHg compounds determination in samples such as soil, sediment and water is rather difficult and the results are also method dependent. In addition, it has been shown that some of the most frequently employed analytical methods may be a subject to spurious MeHg formation in the presence of high concentrations of inorganic mercury and organic matter. These findings have put a number of previous data on MeHg in question and consequently prompt actions were undertaken by a number of well experienced laboratories and producers of CRMs. So far, it is shown that the results obtained by various laboratories using different analytical techniques agree well with certified values in all RMs certified for MeHg. This suggests that comparability of data can be achieved, which however is not a guarantee of the true values.

Animals↗
PubMed1999

Comparison of isokinetic peak force and work parameters in youth with and without mental retardation.

PURPOSE: The purpose of this study was to compare isokinetic knee (flexion and extension) strength of nondisabled youth (ND; 15 males, 15 females; males = 12.7 +/- 2 yr; females = 13.4 +/- 2 yr) and youths with mental retardations (MR, 17 males + 13 females; male = 14.7 +/- 2 yr; females = 13.6 +/- 2 yr). METHODS: Subjects were evaluated on a Kin-Con isokinetic dynamometer at a speed of 60 degrees x s(-1). Parameters measured were peak torque (PT), time to PT, angle of PT, total work (W), and PT hamstrings/quadriceps (HQ) ratio. Peak torque was also corrected by weight (BW) and body mass index (BMI). Peak torque, time to peak torque, angle of peak torque, and total work were analyzed using a 2 x 2 x 2 (groups x gender x muscle) repeated measures analysis of variance (MANOVA). Flexion/extension ratios, BMI, and BW were analyzed by separate 2 x 2 (group x gender) analyses of variance. RESULTS: Results of this study suggest that: 1) while gender differences are apparent in the ND population they are not evident in individuals with MR; 2) knee extension strength is higher for ND youth, thus causing lower PT HQ ratios when compared with those in youth with MR; 3) angle of PT and time to PT were similar among groups; and 4) total work performed is lower in individuals with MR. CONCLUSIONS: It was concluded that parameters of strength production in individuals with MR are not consistent and do not follow the same pattern as their nonretarded peers.

Adolescent↗
PubMed1999

Bolus versus continuous low dose of enalaprilat in congestive heart failure with acute refractory decompensation.

The first dose of angiotensin-converting enzyme (ACE) inhibitors may trigger a considerable fall of blood pressure in chronic heart failure. The response may be dose-related. To determine hemodynamic and systemic oxygenation effects of low-dose enalaprilat, we administered intravenous enalaprilat (0.004 mg/kg) as bolus (group B) or continuous 1-hour infusion (group C) in 20 patients with congestive heart failure due to ischemic heart disease with acute decompensation refractory to inotropic, vasodilator and diuretic therapy. Hemodynamic and systemic oxygenation variables were recorded at baseline (+0 min), +30, +60, +120, +180, and +360 min after the start of intervention. Mean arterial pressure (MAP) (p < 0. 001), mean pulmonary artery pressure (MPAP) (p < 0.001), pulmonary artery occlusion pressure (PAOP) (p < 0.001), oxygen extraction ratio (ER) (p < 0.026) decreased regardless of enalaprilat application. Compared to group B, there was in group C prolonged decrease of MAP, MPAP, PAOP, ER and increase of pulmonary artery oxyhemoglobin saturation in regard to baseline values. Cardiac index, heart rate, central venous pressure and oxygen consumption index did not change. A low dose of intravenous enalaprilat (0.004 mg/kg) can be used to safely improve hemodynamics and systemic oxygenation in congestive heart failure due to ischemic heart disease with acute refractory decompensation.

Aged↗
PubMed1998

The relative cost of children's physical play.

There has been a long-standing debate regarding the functions of play during childhood. An important, but neglected, first step in this debate entails documenting the costs associated with play. In this study we analysed energetic costs (expressed in terms of caloric expenditure) associated with physical play in four field experiments of play in primary school children. Experiment 1 established the concurrent validity of an observational check list to estimate caloric expenditure of children's physical play. Experiment 2 compared caloric expenditure of the play (defined as all behaviour exhibited during play time) for two age groups of children during playtime outdoors and during indoor sedentary activity; caloric expenditure of outdoor activity was greater and was significantly correlated with ambient temperature. In experiment 3, children were observed during indoor play to control for the influence of ambient temperature. Outdoor physical play was more energetically costly than indoor physical play. In experiment 4, children's behaviour was observed outdoors and caloric expenditure for play, games and other activities was compared. Physical play was more costly than other forms of behaviour and games. Estimates of total energetic costs of play ranged from 6 to 15%. Results are discussed in terms of the relatively low caloric costs of play. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1998

Profound circulatory shock following heroin overdose.

A 17-year-old previously healthy girl with profound circulatory shock following a heroin overdose is reported. Except for opiates no other substances and specifically no cocaine were found in the blood and urine samples. Even though the mechanism of shock is not completely understood, severe depression of left ventricular contractility seems to be the predominant reason. Acute right heart failure with decreased pulmonary capillary wedge pressure and arterial vasodilatation resulting in maldistribution of cardiac output cannot be ruled out as possible contributing factors. The shock was successfully reversed with volume loading and a high dose of dobutamine. The recovery was uneventful and the patient was discharged with normal cardiac function.

Adolescent↗
PubMed1998

Treatment of out-of-hospital cardiac arrest in Ljubljana: outcome report according to the 'Utstein' style.

We investigated survival of patients with out-of-hospital cardiac arrest in Ljubljana according to the 'Utstein' style. Ljubljana consists of urban, suburban and semi-rural communities which encompass an area of 1615 km2 with 397306 residents. The area is served by a single response emergency medical system and local family practitioners. Between January 1, 1995 and December 31, 1997 cardiac arrest was confirmed in 966 patients. Cardiopulmonary resuscitation was attempted in 454 patients (47%). Collapse of presumed cardiac etiology (337 patients) was either bystander-witnessed (89%), un-witnessed (9%) or EMS personnel-witnessed (2%). Asystole was documented in 55%, ventricular fibrillation or tachycardia in 36% and other non-perfusing rhythms in 9% of these patients. Lay-bystander basic life support was performed in 19%. Nineteen patients (5.6%) survived to hospital discharge and 12 of them were independent in daily life. The survival of subgroups with bystanders-witnessed collapse and bystanders-witnessed ventricular fibrillation was 6.4 and 13%, respectively. Collapse of non-cardiac etiology (117 patients) was preceded by either respiratory failure (41), politrauma (22), circulatory shock (19), cerebrovascular incident (ten), intoxication (nine), strangulation (seven), electrocution (five) or drowning (four patients). Only five patients (4.2%) survived to hospital discharge. Hospital treatment of patients after successful initial cardiopulmonary resuscitation was associated with high mortality and required considerable resources.

Activities of Daily Living↗
PubMed1998

Positive biochemical effects of a bioartificial liver support system (BALSS) in a porcine fulminant hepatic failure (FHF) model.

This study describes biochemical changes in the plasma and blood of pigs with devascularised livers treated in a bioartificial liver support system (BALSS). Porcine hepatic cells were incubated with collagen-coated dextran microspheres (CDM) for 3 hours and the medium tested to determine cellular metabolic activity. Incubation continued for a further 18 hours during which the hepatic cells attach to the CDM. The CDM-attached cells were inoculated into a hollow fibre bioreactor which was part of an extracorporeal support system. Hepatic cell content of the bioreactor was 6 x 10(9) cells. The system was tested in a controlled trial in pigs prepared in a surgical model of fulminant hepatic failure (FHF). When plasma from FHF pigs was circulated through the device containing hepatic cells, there was significantly less increase in the accumulation of ammonia and most amino acids, together with a decrease in plasma lactate and of one amino acid, compared to control experiments when hepatic cells were excluded. We conclude that primary porcine hepatocytes can contribute beneficial metabolic function in a BALSS.

Adenosine Triphosphate↗