Biomedical subjects

A Brockhaus

Publications and source records attributed to A Brockhaus.

At least 19 recordsLinked to original sources

PubMed1997

The apolipoprotein E epsilon 4 allele is not associated with early onset temporal lobe epilepsy.

A polymorphism of the apolipoprotein E gene, in particular the epsilon 4 allele (ApoE4), has been associated with impaired neuronal phospholipid metabolism and synapse reorganization and has been implicated in several neurodegenerative disorders. Since selective neuronal cell lose and aberrant axonal reorganization represent hall-marks of Ammon's horn sclerosis (AHS) in patients with chronic temporal lobe epilepsy (TLE), the ApoE polymorphism was studied in 125 patients with TLE. The genotype analysis revealed a frequency of 15.5% for epsilon 4, and 74.8% and 9.8% for epsilon 3 and epsilon 2, respectively. These figures were not significantly different from those reported in the normal European population. In addition, no correlation was found between the ApoE4 allelotype and the age of epilepsy onset, seizure type, febrile seizures, family history of epilepsy, surgical outcome and neuropathological findings in patients with TLE. These data virtually exclude ApoE as a susceptibility gene involved in the pathogenesis of early onset TLE or AHS.

Adolescent↗

PubMed1997

Human temporal lobe potentials in verbal learning and memory processes.

Animal experiments and lesion studies have shown the importance of temporal lobe structures for language and memory. We recorded intracranial cognitive potentials from the human lateral and medial temporal lobe in 26 patients with temporal lobe epilepsy undergoing presurgical evaluation, using a word- and a picture-recognition paradigm. Neuropsychological testing included word fluency, verbal reasoning, sustained attention and a verbal learning memory test (VLMT), which was an adapted version of the Rey auditory verbal learning test. Word-specific N400-potentials elicited in the middle temporal gyrus of the dominant left hemisphere (LTL-N400) predicted immediate recall performance after learning, whereas N400s, elicited by words but not pictures in the left anterior medial temporal lobe (AMTL-N400), predicted delayed recall. The number of words that were learned but forgotten after a 30-min delay correlated only with N400s elicited by words in the left anterior medial temporal lobe. Thus, intracranial recordings indicated that different electrophysiological responses in different temporal lobe structures were linked to memory scores from specific neuropsychological tests.

Adolescent↗

PubMed1997

Possibilities and limitations of magnetic source imaging of methohexital-induced epileptiform patterns in temporal lobe epilepsy patients.

The usefulness of MEG-based techniques in lateralizing and localizing the epileptogenic area was investigated in the present study. Spontaneous and methohexital-induced spikes were studied in a group of 15 patients with temporomesial epilepsy using a 37-channel neuromagnetometer. The accuracy of the magnetic source imaging was compared to the results of electrocorticographic (ECoG) recordings. Differences of drug-induced spike densities in the MEG recordings between both sides confirmed a similar lateralizing power of the MEG and ECoG recordings. Source location analyses based on a moving dipole model resp. a rotating dipole model were performed using a spherical head model. After subdivision of the volume of each patient's head, 8 cm3 cubicles containing at least 3 source locations were projected onto the individual MRI scan and resulted in source locations within or close to the presurgically defined primary epileptogenic area only in 3 of the 15 patients. Spike induction by methohexital has the advantage of shortening the recording period as compared to recordings of interictal epileptiform discharges. However, the correlation analyses of spike densities from MEG and ECoG recordings and the source location analyses from MEG recordings indicate that spike generated in deep temporomesial structures may escape the MEG registration.

Adolescent↗

PubMed1997

Methohexital-induced changes in spectral power of neuromagnetic signals: beta augmentation is smaller over the hemisphere containing the epileptogenic focus.

Previous research has suggested that methohexital, a short-term barbiturate, alters activity in the primary epileptogenic area. It can be assumed that drug-induced activation of the epileptogenic focus provides a rapid and safe method to obtain a sufficient amount of information relevant for the lateralization and localisation of the primary epileptogenic area. This study shows that methohexital changes spectral power in the beta band derived from magnetoencephalographic (MEG) signals over the hemisphere ipsilateral to the primary epileptogenic area. This effect was demonstrated for 10/13 of the investigated patients suffering from unilateral temporal lobe epilepsy (TLE). The side and location of the primary epileptogenic area of these patients (5 left TLE, 8 right TEL) was determined invasively during presurgical evaluation. During a 1-2 minute interval after intravenous bolus injection of 100 mg methohexital a clear lateralization effect in the beta band was observed, which differed marginally between fronto-central, fronto-temporal and temporo-parietal brain regions. In addition, bilateral spectral power changes were obtained in the theta, alpha and gamma bands that differed between brain regions. Analyses of simultaneously recorded scalp electroencephalographic (EEG) data revealed effects consistent with those of the MEG analysis. The reduced enhancement of beta band spectral power of MEG recordings provides a potential application for the non-invasive lateralization of the primary epileptogenic area.

Adult↗

PubMed1996

[Lead and cadmium content in deciduous teeth of children of Stolberg and other cities of North-Rhine-Westphalia: a chronological trend 1968-1993].

The levels of lead and cadmium were determined in deciduous teeth (incisors only) of children living in Stolberg and some other cities located in North-Rhine-Westfalia, Germany. The Stolberg children were born in 1968-1973 (group 1; n = 103) and 1982/1983 (group 2; n = 103). The other children (n = 109) were born between 1979 and 1986. All teeth were analysed within the same analytical series by atomic absorption spectrometry (AAS). The results show that the average levels of lead and cadmium in milk teeth have decreased significantly in the time period from 1970 to 1990. Considering the Stolberg children the fall of tooth lead was about 50% and the fall of tooth cadmium was about 60%. Children from other cities show a comparable decrease of tooth lead and tooth cadmium. The results indicate that a significant decrease of the lead body burden and cadmium body burden of children and probably also of the general population of Germany has occurred during the last years.

Age Factors↗

PubMed1995

Complex partial seizures of temporal lobe origin in children of different age groups.

The semiology of complex partial seizures (CPS) of temporal lobe origin in adults is well known and is important in establishing seizure localization in patients considered for epilepsy surgery. In contrast, the behavioral features of temporal lobe seizures (TLS) in children described in the literature have not been consistent. In the present study, we investigated children with TLS to compare their attacks to TLS occurring in adults. The study was based on video recordings of 29 children with TLS aged 18 months to 16 years. Children were included, if they became seizure-free after temporal lobectomy (except 4 children with a marked reduction in seizure frequency and 1 with isolated auras), and if clear unitemporal seizure onset in ictal EEG-recordings, unilateral radiological lesions, and corresponding histopathological findings were detected. Children aged > 6 years had TLS with features similar to those of adults. In younger children, typical semiology included symmetric motor phenomena of the limbs, postures similar to frontal lobe seizures in adults, and head nodding as in infantile spasms. We concluded that the clinical features of TLS in younger children can be misleading and should therefore be considered with caution in selecting patients for surgical procedures on the temporal lobe.

Adolescent↗

PubMed1993

[Heavy metal pollution of soil and garden products of Stolberg home gardens and lead and cadmium pollution of small farms in Stolberg].

Cadmium, lead and zinc were determined in garden soils and vegetable products from private gardens located in a lead/zinc smelter area (Stolberg, Germany). At the same time lead and cadmium were measured in blood and urine samples collected from 90 garden owners. Inspite of extraordinary high levels of cadmium and lead in garden soils and vegetables, blood lead, blood cadmium and urine cadmium levels were not or only slightly elevated in the gardeners when compared to a reference group of subjects from the same area who did not consume home-grown vegetables and fruits. The results show that high levels of pollutants in soil and vegetables are not necessarily associated with an increased burden of pollutants in the human body, and that the transfer of pollutants from soil to humans might have been overestimated in some cases. Moreover, the results underline the preventive character of the guideline values presently applied with respect to the evaluation of soil contaminants.

Cadmium↗

PubMed1992

[Mercury exposure of the population. IV. Mercury exposure of male dentists, female dentists and dental aides].

Urinary mercury levels were determined in 22 dentists and 46 dental nurses and assistants working in 15 private dental offices in West-Germany. For comparison, urinary mercury levels of 29 subjects without occupational mercury exposure were studied. On average, urinary mercury in dental personnel was higher than in the reference group. Individual mercury levels, however, were all significantly below present occupational exposure limits. Urinary mercury was significantly correlated with the number of amalgam fillings in dental personnel as well as in the reference group. Following administration of Dimaval a significant increase of mercury excretion was observed in both groups. Regarding total exposure to mercury in dental personnel, the contribution of mercury exposure from the occupational environment is of the same order of magnitude as their exposure from their own amalgam fillings. Dental nurses were found to be more exposed than dentists. This finding seems to be related predominantly to the larger number of amalgam fillings in dental nurses.

Adult↗

PubMed1992

[The mercury exposure of the population. III. Mercury mobilisation by DMPS (Dimaval) in subjects with and without amalgam fillings].

The urinary excretion of mercury (per 24 h) was determined in 29 subjects before and after application of DMPS (2.3-dimercapto-1-propane sulfonic acid, 300 mg per os). A 6-7 fold increase of mercury excretion was noted after application of DMPS. Subjects with amalgam fillings excreted significantly more mercury before as well as after application of DMPS than subjects without amalgam fillings. Urinary mercury excretion was significantly correlated with the number of amalgam fillings. About 50% of the variance of urinary mercury can be explained by the number of amalgam fillings. The results show that the release of mercury from amalgam fillings represents the main source of mercury exposure in subjects with amalgam fillings.

Adult↗

PubMed1991

High lead content of deciduous teeth in chronic renal failure.

Lead is suspected to contribute to the progression of kidney disease. Lead content of blood and deciduous teeth was determined in 22 children aged 5-14 years at different stages of chronic renal failure (CRF). In addition, individual lead exposure was estimated from histories. The results were compared with a control group of 20 siblings or neighbours of patients living in the same environment (C1), and to a group of children known to be free of excessive lead exposure (C2). The mean blood lead concentration of patients was normal (mean 2.9 micrograms/dl, range 1.1.-10.1). Mean dental lead content was 2.8, 1.7 and 1.4 micrograms/g in CRF, C1 and C2, respectively. It always exceeded that of healthy peers. Increased dental lead content was associated with a high risk of exposure. It is suggested that both an increased lead uptake and renal dysfunction may contribute to the increased lead burden in children with CRF.

Adolescent↗

PubMed1990

Hypalgesic efficacy of acupuncture on experimental pain in man. Comparison of laser acupuncture and needle acupuncture.

The analgesic effect of acupuncture on cutaneous heat stimuli of 43 degrees C has been evaluated in a controlled experimental study with healthy, informed volunteers. Laser acupuncture was administered to 39 probationers using a helium-neon laser under double-blind conditions. The point Hegu (L.I.4) and Jianqian (Extra.) on both sides were each irradiated for 1 min. Forty probationers were needled with stainless steel needles in the point Hegu (L.I.4) on both sides under single-blind conditions. Pain threshold was measured in terms of the time (in msec) that the probationers needed to perceive the cutaneous heat stimulus of 43 degrees C. The painful stimulus was generated by a computer-controlled standardized procedure. The Wilcoxon test was used for the statistical evaluation. Laser acupuncture did not change the pain threshold. Needle acupuncture did, however, increase the pain threshold compared with the initial value (alpha = 0.1%). The difference compared with the control group, where a placebo point was needled, was also significant (alpha = 5%). This controlled experimental study proves the analgesic effect of needle acupuncture on painful heat stimuli. Laser acupuncture had no effect on pain threshold in this study.

Acupuncture Points↗

PubMed1990

[Exposure to mercury in the population. I. Mercury concentrations in the urine of normal subjects].

The levels of mercury were determined in 24 h urine samples collected from 703 subjects (age 1-79 years) living in the Eastern part of the Ruhr area (West-Germany). The mean HgU level was 0.75 micrograms/l (range less than 0.1-19.3 micrograms/l) and the mean HgU level standardized for creatinine was 0.64 micrograms/g creatinine (range: less than 0.1-27.4 micrograms/g creatinine). The mean mercury excretion per 24 h was 0.48 micrograms in subjects less than 18 years and 0.99 micrograms in subjects greater than 18 years. Females were found to have, on average, higher HgU levels and also a higher excretion of mercury per 24 h than males. Subjects greater than 18 years had significantly higher HgU levels than subjects less than 18 years of age. The effect of age was found to be substantially more pronounced in females than in males. Smoking did not affect the urinary mercury excretion.

Adolescent↗

PubMed1990

[Exposure to mercury in the population. II. Mercury release from amalgam fillings].

Urinary levels of mercury (HgU) were measured in 93 males and females aged 18-63 years. Subjects with amalgam fillings (n = 72) had, on average, significantly higher levels of mercury in urine (mean = 0.57 microgram Hg/l and 0.79 microgram Hg/g creatinine, respectively) than subjects without amalgam fillings (n = 21; mean = 0.18 micrograms Hg/l and 0.24 microgram Hg/g creatinine, respectively). Urinary mercury excretion was significantly correlated with the number of amalgam surfaces (log HgU (microgram/l) vs. number of amalgam fillings: r = 0.435, P less than 0.001; log HgU (microgram/g creatinine) vs. number of amalgam fillings: r = 0.575, p less than 0.001). The results indicate that internal mercury exposure from amalgam fillings is, on average, higher than internal exposure to mercury from food and other sources.

Adult↗

PubMed1990

[Lead and cadmium burden of children in Stolberg].

In 1989, blood lead and blood cadmium levels were determined in 229 children (age 6-7 years) living at Stolberg (West Germany). The area of Stolberg is heavily polluted by lead and other toxic metals due to emissions from a large primary lead smelter. The mean blood lead level was 6.3 micrograms/dl (range 2.6-15.5 micrograms/dl) and the mean blood cadmium level was 0.14 microgram/l (range less than 0.1-0.5 microgram/l). The blood lead levels were affected by the following factors: living in the central urban area with high lead levels in dust fall-out; living in a family of foreigners; involuntary inhalation of smoke at home; living in a family with a family member employed in the lead industry. Children from foreign families also had higher blood cadmium levels than children from German families. However, inhalation of tobacco smoke did not affect the blood cadmium levels. In total, there has been a significant decline of blood lead and blood cadmium levels among children from the Stolberg area since 1982.

Air Pollutants, Occupational↗

PubMed1990

[Comparative studies of the effect of quartz glass and quartz DQ-12 in inhalation tests in rats].

Fibrogenic effects of amorphous quartz dusts are discussed more and more during recent years. In order to study alterations due to amorphous silica (quartz glass VP 203-006) in comparison with crystalline quartz (DQ-12), an inhalation experiment in rats was carried out. Male Wistar rats were separated in two dust exposed groups (n = 35) and one control group (n = 30). The experiment was carried out in inhalation chambers with a slowly rotating animal cage for 12 months, 7 h per day, and 5 days per week. The dust concentration was 10 mg/m3. After 4 and after 8 months of inhalation, 5 animals of each group were sacrificed. After 12 months 15 rats of the dust exposed groups and 10 controls were euthanized. The remaining animals were kept for another 12 months post-inhalation period. Regarding the macroscopical appearance of the lungs, the relative organ weights and the histomorphological reaction pattern, marked dust depending differences are obvious. In the lungs of DQ-12-exposed animals diffuse structural changes occur, including fibrosis and severe reaction of macrophages. Histology of lungs from quartz glass exposed animals reveals only a slight and focally arranged cellular reaction with a few collagenous fibers. However, in both dust exposed groups the mediastinal lymph nodes are extremely enlarged with severe fibroses. Additionally, the following blood parameters were determined: lysozyme, ACE, GOT, GPT, and AP. The most pronounced changes are detectable in lysozyme and GOT after DQ-12 exposure. After quartz glass exposure, the levels of these parameters are similar to the controls. These results show that the amorphous quartz tested in this experiment (quartz-glass VP 203-006) has to be considered as a compound with certain biological effects. The establishing of occupational standards seems to be justified. But, assessing the effects, the different physical and/or chemical properties of various amorphous quartz dusts have to be considered.

Alanine Transaminase↗

PubMed1990

[Lead and cadmium content in deciduous incisors of children from Duisburg and Gummersbach--developing trend 1976-1988].

Shed deciduous teeth (incisors only) were collected from children (n = 199) living in Duisburg and Gummersbach (F.R.G.) in 1976 and 1988. The teeth were analysed for lead and cadmium. Considering all teeth, there was a significant of tooth lead and tooth cadmium from 1976 to 1988. The reduction was between -40 and -50% for tooth lead and -45% for tooth cadmium. Regarding tooth lead, the reduction was more pronounced in children from Duisburg, an area heavily polluted by lead and other heavy metals due to the presence of large iron and steel plants and a large lead-/zinc smelter. Teeth from the upper jaw were found to have higher lead and calcium concentrations than teeth from the lower jaw. Moreover, it was found that central incisors had higher lead and cadmium concentrations than lateral incisors. Even after the effects of jaw and tooth type had been allowed for, the reduction of tooth lead and tooth cadmium could be demonstrated. Children living in pre-war houses were found to have higher tooth lead and tooth cadmium levels than children living in post-war houses. The higher lead and cadmium burden of children living in old houses seems to be related to a higher degree of exposure to lead and cadmium via drinking water resulting from the release of these metals from old zinc-plated steel water pipes. In total, our results indicate that there has been a significant decrease of lead and cadmium exposure in West-German children since the mid-70s. The reduction of tooth lead levels parallels the decrease of blood and bone lead levels, which has been observed in previous studies.

Cadmium↗

PubMed1990

[Blood lead and blood cadmium concentrations in 55-66-year-old women fron different areas of Nordrhein-Westfalen--chronological trends during 1982-1988].

Blood lead levels were determined in 3098 55-66 year-old women living in different areas of Northrhine-Westphalia (F.R.G.). Blood cadmium levels were determined in a subgroup of 2538 women. The studies were performed between 1982 and 1988. The results show that there has been a further fall of blood lead levels in the general population of West-Germany since the CEC blood lead surveys of 1979 and 1981. A comparable reduction of blood cadmium was not noted. Residents of large urban agglomerations had, on average, slightly higher blood lead levels than residents of small cities located in rural areas (+0.2-0.5 microgram/dl). With regard to blood cadmium, no differences were seen. Smokers were found to have, on average, 3-4 times higher blood cadmium levels than non-smokers. Blood lead was also elevated in smokers when compared to non-smokers. The highest blood lead levels recorded were in the range of 15-30 micrograms/dl. The data further suggest that lead mobilization during conditions of bone demineralization, e.g. in cases of osteoporosis, does not result in toxic blood lead levels in postmenopausal women.

Aged↗

PubMed1989

Levels of benzene and other volatile aromatic compounds in the blood of non-smokers and smokers.

The concentrations of benzene, toluene, ethylbenzene, and o-, m-and p-xylene were measured in venous blood samples collected from 13 non-smokers and 14 cigarette smokers. The blood samples were analysed by a purge and trap technique followed by gas chromatography/mass spectrometry/computer analysis. The above-mentioned volatile organic compounds (VOC) could be detected in measurable amounts in all blood samples. This finding seems to reflect the ubiquitous exposure of humans to these agents in the urban environment, in non-smokers as well as in smokers. Smokers were found to have significantly higher blood concentrations of benzene (median 547 ng/l) and toluene (median 2201 ng/l) than non-smokers (median 190 ng/l and 1141 ng/l, respectively). The concentrations of ethylbenzene and xylenes also tended to be higher in smokers when compared to non-smokers. The different concentrations of these compounds in the blood of non-smokers appear to reflect the common concentration pattern found in outdoor urban air as well as in indoor air and also seem to be influenced by the different blood/air partition coefficients of these compounds. The results indicate that smoking is associated with a significant additional exposure to VOC, in particular to benzene and toluene.

Benzene Derivatives↗