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H Wichmann

Publications and source records attributed to H Wichmann.

At least 19 recordsLinked to original sources
PubMed2006

Assessment of the environmental impact of landfill sites with open combustion located in arid regions by combined chemical and ecotoxicological studies.

Two different waste disposal sites in Jordan were investigated in order to determine the environmental situation in context with waste disposal techniques. One landfill, located at Marka/Amman, had been closed about 25 years ago and covered with soil. Here, the waste had been actively open combusted and openings in the cover, still emitting smoke, indicated that waste was still smoldering inside the landfill's body. The second disposal site close to Ekeeder/Irbid is still operated. On this ground, the solid waste is not intentionally burned, although spontaneous fires frequently come up. Samples of waste, soil, and entrained dust were collected and analyzed. From the solid samples, respectively, their eluates, sum parameters, ecotoxicological effects as well as contents of elements/heavy metals and organic pollutants (PAH, PCDD/F) were determined. In general, the Ekeeder-samples were low-contaminated. The investigation of the Marka-samples showed higher contamination of the site's center, clearly being influenced by combustion processes. A significant contamination of the landfill's vicinity by its emissions could not be derived from the analytical data. Ecotoxicological investigations, applying a bio-test battery, revealed correlations with the sum parameters but not with the trace pollutants. Thus, the Marka-samples with the highest measured values of sum parameters caused adverse effects on three different test species, whereas other samples from Marka and Ekeeder had small or no effects. The results of these investigations depict the influence of different disposal techniques on the contamination situation of a landfill and they shall contribute to assess the conditions of other disposal sites in (semi)arid regions.

Benzofurans↗
PubMed2003

Isomer specific synthesis using the Suzuki-coupling. Polychlorinated terphenyls as standards for environmental analysis.

Defined polychlorinated terphenyl (PCT) single congeners as reference standards are the prerequisite for the development of analytical methods for their determination and quantification in the environment. The selective synthesis of PCTs for environmental analytical purposes by application of the Suzuki-coupling reaction is described. Under easily modified standard reaction conditions of this coupling process the PCTs can be obtained by reaction of benzeneboronic acids with dibromobenzenes mostly in good yields, as described by the synthesis of following PCT congeners: p-PCT (3,3("),5,5(")-tetrachloro-, 2,2("),4,4(")-tetrachloro-, 2('),3,3("),5,5(")-pentachloro-); m-PCT (3,3("),5,5(")-tetrachloro-) and o-PCT (3,3("),5,5(")-tetrachloro-). The terphenyl congeners were characterized by NMR (1H, 13C)- and FT-IR-spectroscopy. Their purity was checked by GC/MS analysis. The experimental and quantum-chemically calculated FT-IR-spectra were compared and it was shown, that the determination of the chlorine substitution pattern in the terphenyl congeners by their typical absorption spectra is possible.

Environmental Monitoring↗
PubMed2003

Influence of heavy metals on the formation and the distribution behavior of PAH and PCDD/F during simulated fires.

Combustion experiments were performed with an artificial fire load (polystyrene and quartz powder) in a laboratory scale incinerator in the presence of gaseous HCl to simulate accidental fire conditions. The aim of this investigation was to trace back the alterations of the formation and the distribution behavior of PAH and PCDD/PCDF to the presence of CuO or a mixture of metal oxides (CdO, CuO, Fe(2)O(3), PbO, MoO(3), ZnO). The total amount of the 16 PAH target compounds was reduced by the factor of 5-9 when the mixture of metal oxides was present rather than merely CuO. PAH patterns as well as their distribution behavior were significantly influenced by these oxides. In general, transportation inside the installation was enhanced for most of the 16 analyzed PAH. Only fluorene and dibenzo[a,h]anthracene were transported to a smaller extent. In contrast to PAH, total concentrations of PCDD were increased by factor 9 and of PCDF by factor 10, respectively, when CuO was present. Adding the mixture of metal oxides resulted in an increase of PCDD by factor 14 and of PCDF by factor 7. CuO and the mixture of metal oxides had a different influence on the PCDD/F homologue patterns. For instance, the HxCDF to OCDF ratio after incineration without any metal oxide was 1 to 6, whereas addition of CuO or the mixture of the metal oxides shifted the HxCDF to OCDF ratios towards 1 to 40 or 1 to 17, respectively. Combustion along with CuO increased transportation of higher chlorinated PCDF congeners, whereas the mixture of the metal oxides caused a strong decrease of PCDF distribution throughout the system.

Fires↗
PubMed2003

Linkage analysis of candidate regions using a composite neurocognitive phenotype correlated with schizophrenia.

As schizophrenia is genetically and clinically heterogeneous, systematic investigations are required to determine whether ICD-10 or DSM-IV categorical diagnoses identify a phenotype suitable and sufficient for genetic research, or whether correlated phenotypes incorporating neurocognitive performance and personality traits provide a phenotypic characterisation that accounts better for the underlying variation. We utilised a grade of membership (GoM) model (a mathematical typology developed for studies of complex biological systems) to integrate multiple cognitive and personality measurements into a limited number of composite graded traits (latent pure types) in a sample of 61 nuclear families comprising 80 subjects with ICD-10/DSM-IV schizophrenia or schizophrenia spectrum disorders and 138 nonpsychotic first-degree relatives. GoM probability scores, computed for all subjects, allowed individuals to be partly assigned to more than one pure type. Two distinct and contrasting neurocognitive phenotypes, one familial, associated with paranoid schizophrenia, and one sporadic, associated with nonparanoid schizophrenia, accounted for 74% of the affected subjects. Combining clinical diagnosis with GoM scores to stratify the entire sample into liability classes, and using variance component analysis (SOLAR), in addition to parametric and nonparametric multipoint linkage analysis, we explored candidate regions on chromosomes 6, 10 and 22. The results indicated suggestive linkage for the familial neurocognitive phenotype (multipoint MLS 2.6 under a low-penetrance model and MLS>3.0 under a high-penetrance model) to a 14 cM area on chromosome 6, including the entire HLA region. Results for chromosomes 10 and 22 were negative. The findings suggest that the familial neurocognitive phenotype may be a pleiotropic expression of genes underlying the susceptibility to paranoid schizophrenia. We conclude that use of composite neurocognitive and personality trait measurements as correlated phenotypes supplementing clinical diagnosis can help stratify the liability to schizophrenia across all members of families prior to linkage, allow the search for susceptibility genes to focus selectively on subsets of families at high genetic risk, and augment considerably the power of genetic analysis.

Adolescent↗
PubMed2002

Thermal formation of PBDD/F from tetrabromobisphenol A--a comparison of polymer linked TBBP A with its additive incorporation in thermoplastics.

For a long period, polybrominated flame retardants are under discussion because of the formation of polybrominated dibenzo-p-dioxins (PBDD)/dibenzofurans (PBDF) (PBDD/F) in case of thermal stress. Concerning polymer linked tetrabromobisphenol A (TBBP A), formation of PBDD/F was commonly presumed to be sterically hindered because of the covalent fixation into the polymer backbone. Combustion experiments with additively incorporated TBBP A compared with its polymer linkage revealed, that this assumption is incorrect and has to be revised. Under same conditions, similar PBDD/F concentrations in the range of 17.5-19.6 mg PBBD/F per kg TBBP A applied were analyzed. PBDD/F homologue distribution patterns were almost identical predominated by low brominated PBDF. These findings for PBDD/F formation have to be considered in future discussions regarding thermal stress caused by combustion or recycling processes, including other flame retardants bound in polymer matrix, e.g. polybrominated polystyrene (PS), or those with molecular structures showing less analogy to PBDD/F, like hexabromocyclododecane. The second aspect introduced, is the influence of different plastics on the formation rates of PBDD/F. In this context, combustion experiments were performed in an atmosphere consisting of synthetic air and HBr. PBDD/F concentrations were 8.47 mg/kg polyethylene, 1.67 mg/kg PS, 3.92 mg/kg phenolic resin and 18.1 mg/kg epoxy resin. Distribution patterns of PBDD/F homologues could partly be correlated with the occurrence of the precursors polybrominated benzenes and phenols.

Benzofurans↗
PubMed2001

Distribution behavior of heavy metals investigated in a laboratory-scale incinerator.

The distribution behavior of Pb, Cd, Fe, Cu, Mo and Zn was determined in a laboratory-scale incinerator. Points of interest were the influence of the temperature and combustion atmosphere on the emission rates of those metals, orientating at frequent combustion conditions of accidental fires. The experiments were carried out at 600 degrees C and 800 degrees C in N2, air, N2 + HCl and air + HCl atmospheres. Furthermore, the influence of the matrix (quartz, polyethylene and cellulose powder) on the distribution behavior of the heavy metals was investigated as well. It was determined whether the distribution behavior of Cu, Pb and Cd were affected by the other heavy metals. In conclusion, it was found that in air and N2 atmosphere a temperature increase from 600 degrees C to 800 degrees C and the addition of the matrix had no effect on the evaporation rates of the heavy metals, except for Cd. Addition of gaseous HCl led to increased evaporation of the heavy metals. The increase of the evaporation rates during the experiments with matrix was higher for Fe, remained the same for Pb, Cd, Zn, and lower for Mo and Cu compared to the experiments without matrix.

Air Pollutants↗
PubMed2000

Duration and frequency mismatch negativity in schizophrenia.

OBJECTIVES: The aim of the present study was to elucidate the reasons for apparent inconsistencies in the schizophrenia literature with respect to the mismatch negativity (MMN) waveform of the event-related potential (ERP). While most previous research has shown that MMN is reduced in schizophrenia, there are a small number of studies reporting that frequency MMN is not reduced. METHODS: We recorded ERPs to auditory stimuli with different frequencies and durations from patients with schizophrenia (N = 14) and control subjects (N = 17) of similar age and sex. MMNs to small but discriminable frequency deviants were contrasted with large frequency deviants and duration deviants. RESULTS: Only the MMN to duration deviants was significantly reduced in patients, although there was evidence of a similar trend for large frequency deviants. CONCLUSIONS: The results together with a review of the frequency MMN literature suggest that there are 3 variables which are important in determining whether patients exhibit a reduced MMN to frequency deviants: deviant probability, degree of deviance and interstimulus interval. The results also indicated that patients with schizophrenia may have particular deficits in processing the temporal properties of auditory stimuli. This finding has implications for the pathophysiology of the disorder as time-dependent processing is reliant on the integrity of an extensive network of brain areas consisting of auditory cortex, areas of pre-frontal cortex, the basal ganglia and cerebellum.

Acoustic Stimulation↗
PubMed2000

Phenotypic markers as risk factors in schizophrenia: neurocognitive functions.

OBJECTIVE: To review the literature on neurocognitive measures as risk markers for schizophrenia and to present data from the Perth family study of schizophrenia. Of all the risk markers that have been identified, the most promising are deficits in sustained attention. METHOD: Inclusion in the review was determined by whether the research addressed a number of key questions: methods of assessing sustained attention; evidence of sustained attention deficits in patients and first-degree relatives including children; the importance of attentional dysfunction in the schizophrenic process and functional outcome; and the biological basis of sustained attention deficits. RESULTS: Sustained attention deficits are evident in both patients and a proportion of their first-degree relatives, a finding replicated in preliminary data from the Perth family study. The literature suggests that the attention deficit is a stable enduring trait that is independent of clinical state. The neural basis of the deficit may be a functional disconnection between prefrontal and parietal cortex. Attention impairment is an important predictor of functional outcome in patients and the development of social dysfunction in adulthood in the at-risk offspring of patients. However, sustained attention deficits that are measured in childhood results in an unacceptable high false-positive rate (21%) when predicting which at-risk offspring of parents with schizophrenia will develop a schizophrenia spectrum disorder, although the overall classification accuracy (78%) is impressive. CONCLUSIONS: The main findings are that sustained attention deficits are important risk markers for schizophrenia but need to be supplemented by other neurocognitive risk markers to improve predictive accuracy.

Adult↗
PubMed1999

Surface contamination with PASH, PAH and PCDD/F after fire accidents in private residences.

Surface samples were taken from two private residences after real fire accidents. The goal was, to determine the surface contaminations with polycyclic aromatic sulfur heterocycles (PASH), as representatives of a substance class, not investigated in this context, by now, polycyclic aromatic hydrocarbons (PAH) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F). Analytical method for the determination of PASH was developed for the respective matrix. Concentrations measured ranged between 1.70 and 465 micrograms/m2 for PASH, 34.3 and 58,800 micrograms/m2 for PAH (EPA), and 4.15 and 1,300 ng/m2 for PCDD/F, as well. Obviously, PASH were formed during the fire accidents. Nevertheless, PAH were the most relevant pollutants after these small fires.

Benzofurans↗
PubMed1999

Release of polychlorinated dibenzo-p-dioxins and dibenzofurans by setting off fireworks.

Selected pyrotechnic articles were set off under laboratory conditions. Residues and vapors of smoke as well as unburnt charges were analyzed for polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/F) and their precursors chlorinated benzenes and phenols. The contamination of the selected products with these organic xenobiotics proved to be very variable. Remains of fireworks contained octachlorinated dioxins and furans up to 142 ng I-TEQ/kg as well as hexachlorobenzene in the range of 0.05 to 1,400 mg/kg. The deflagration of detonating compositions usually resulted in a dispersion of contaminants, whereas continuously burning flare compositions partially led to a thermal decomposition of organic pollutants. A significant rate of formation of polychlorinated dioxins and furans was observed when setting off blue-lightning rockets and fountains. Further investigations revealed that even high temperatures during the deflagration of black powder charges could not suppress the formation of PCDD/F from appropriate precursors.

Benzofurans↗
PubMed1999

Respiratory diseases and allergies in two polluted areas in East Germany.

This cross-sectional epidemiological study collected health data for 2,470 school children between 5 and 14 years of age (89% of eligible children) who had lived most of their lives in either one of two counties strongly impacted by industrial pollution (Bitterfeld and Hettstedt) or in a neighboring county without any sources of industrial pollution (Zerbst). The objective of the study was to examine whether regional differences--with respect to the occurrence of childhood respiratory diseases and symptoms or allergies--exist and, if such differences are found, whether they persist when we adjust for the effects of known risk factors such as medical and sociodemographic factors or factors related to the indoor environment. Controlling for medical, sociodemographic, and indoor factors, according to parental reports, children residing in Hettstedt have about a 50% increased lifetime prevalence for physician-diagnosed allergies, eczema, and bronchitis compared to children from Zerbst and about twice the number of respiratory symptoms such as wheeze, shortness of breath, and cough without cold. Sensitization to common aeroallergens according to skin prick tests [odds ratio (OR) = 1.38; 95% confidence interval (CI), 1.02-1.86] and specific IgE levels (OR = 1.75; CI, 1.31-2.33) was more common for children from Hettstedt than children from the nonpolluted county. Bitterfeld children, on the other hand, more often received a diagnosis of asthma and eczema than children residing in Zerbst and also showed slightly increased sensitization rates. In conclusion, industrial pollution related to mining and smelting operations in the county of Hettstedt were associated with a higher lifetime prevalence of respiratory disorders and an increased rate of allergic sensitization in children between the ages of 5 and 14 years. Further studies are needed to determine what role the high dust content of heavy metals plays in Hettstedt.

Adult↗
PubMed1997

Serum immunoglobulin level and skin prick test response.

OBJECTIVE: The relation of viral infections and allergic diseases is inconclusive. The objective of the analysis therefore was to examine the relation between immunoglobulin levels and sensitization to common allergens as measured by the skin prick test (SPT). METHODS: In a population-based study of 2,470 children, 2,188 skin prick tests, and 2,042 blood samples could be analyzed. RESULTS: At least one positive SPT was observed in 19.2% of the children. IgA und IgG levels did not show any association with SPT response. As expected, there was a sharp increase in the two highest quartile groups of IgE (p for trend <0.0001), while the prevalence of positive SPT continuously decreased with higher IgM levels (p for trend 0.002). This effect of IgM could be seen for all allergens examined. If an upper respiratory tract infection was reported one week prior to testing, the prevalence of a positive SPT was also reduced by nearly one half, however, this association was not significant. CONCLUSIONS: Since IgM has a half-life of approximately 5 days, the inverse association found between IgM and the prevalence of positive SPT seems to be a transient effect of a prior infection.

Allergens↗
PubMed1996

Dioxins and furans in the Jordanian environment. Part 2: Levels of PCDD and PCDF in human milk samples from Jordan.

Thirty individual human milk samples were gathered from five main towns in Jordan. They were mixed to six pooled samples and analyzed for PCDD and PCDF. All examined samples were contaminated with 1,2,3,4,6,7,8-HeptaCDD (3.2-96.0 ng/kg fat) and OctaCDD (29.0-147 ng/kg fat). The calculated TEQ (BGA)-values range between 0.26 and 60.32 ng TEQ/kg fat, which are all above the calculated tolerable concentration of 0.19 ng TEQ/kg milk fat.

Adult↗
PubMed1992

Endocytosis in yeast: evidence for the involvement of a small GTP-binding protein (Ypt7p).

From the budding yeast S. cerevisiae, we have cloned a gene, YPT7, that encodes a GTP-binding protein belonging to the Ypt family of ras-related proteins. The 208 amino acid protein shares identical effector domain and C-terminal sequences with the mammalian Rab7 protein. YPT7 gene disruption did not impair cellular growth at temperatures ranging from 17 degrees C to 37 degrees C. ypt7 null mutants are characterized by highly fragmented vacuoles and differential defects of vacuolar protein transport and maturation. The uptake of alpha factor pheromone by wild-type and Ypt7p-deficient cells was found to be indistinguishable, but in mutant cells lacking Ypt7p, degradation of the endocytosed pheromone was severely inhibited. Our findings suggest a role of Ypt7p in protein transport between endosome-like compartments.

Amino Acid Sequence↗
PubMed1988

[Once cesarean section--always cesarean section?].

Between 1975 and 1985 from 522 patients, who had undergone caesarean section during their previous delivery or deliveries, per cent 63 have been delivered vaginally and 37 per cent with a caesarean section (52.8% primary, 47.2% secondary). The rate of spontaneous labour was higher, if patient had a spontaneous delivery before caesarean section or the first caesarean section has been performed because of a placenta praevia, a breech presentation or a fetal distress syndrome. Cephalopelvic disproportion went on in 67.2 per cent with a caesarean section. Rupture of the scare occurred in 2.9 per cent. Expectative management of delivery is justified following previous caesarean section. Oxytocin infusions are possible in cases if internal tocography will be done.

Cardiotocography↗
PubMed1980

[Systems and methods in the processing of carcasses, abattoir offals and foodstuff waste (author's transl)].

The large variety of qualities and quantities of raw material in numerous plants demands specific methods of processing. Each process has to guarantee full sterilization of the raw material and produce profitable products as well as to prevent as far as possible the recontamination of the products. In principle the processes are devided in the dry-rendering technology and the wet-rendering technology. The distinctive mark is the time of degreasing of the material during the process. The device that is nowadays used for the steps of sterilizing, drying and degreasing is described and the most important advantages and disadvantages are pointed out. Each technology results from a suitable combination of particular apparatusses and equipment. The eleven processes that are used in the rendering industry at present time are described with their positive and negative aspects.

Abattoirs↗