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Biomedical subjects

H Hessel

Publications and source records attributed to H Hessel.

15 recordsLinked to original sources
PubMed2006

Heart rate variability, hemostatic and acute inflammatory blood parameters in healthy adults after short-term exposure to welding fume.

The present study aimed to investigate, whether short-term experimental exposure to high levels of welding fumes would be capable of exerting acute effects in healthy subjects. Specifically, we assessed cardiovascular function in terms of heart rate variability (HRV) as well as the concentrations of inflammatory mediators and hemostatic proteins in blood as outcome measures. Twenty subjects without a history of airway and cardiovascular diseases were exposed to either control air or welding fume for 1 h on 2 separate days under standardized conditions. The median concentration of the alveolar particle fraction during welding was 3.5 mg/m(3 )(quartiles: 1.4-6.3 mg/m(3); range 1.0-25.3 mg/m(3)). Five hours later a panel of clinical assessments was performed, including HRV measurement and drawing of blood samples. There were no changes in symptom ratings or lung function after welding fume exposure. Exposures did also not differ regarding effects on time- and frequency-domain parameters of HRV. Similarly, blood leukocyte numbers, cell differentials and the blood levels of fibrinogen, C-reactive protein, antithrombin III, factor VIII, von Willebrand factor, ristocetin cofactor, sICAM-1, tumor necrosis factor alpha, interleukin 6, interleukin 8 and epithelial neutrophil activating peptide 78 were not altered by welding fume inhalation. However, there was a significant fall in the level of endothelin-1 (P < 0.01). In conclusion, the data did not indicate effects of clinical significance of a short-term high-level exposure to welding fumes on HRV or a set of blood hemostatic and acute inflammatory parameters in healthy subjects. The small but statistically significant effect on endothelin levels demonstrated that measurable effects could be elicited even in these individuals. Overall, welding fumes are not likely to exert acute cardiovascular effects in healthy individuals.

Adult↗
PubMed2001

The genotoxic risk of hospital, pharmacy and medical personnel occupationally exposed to cytostatic drugs--evaluation by the micronucleus assay.

The aim of this study was to evaluate the genotoxicity of cytostatic drugs in hospital and pharmacy employees (n=100), occupationally exposed. The micronucleus assay was used to study lymphocytes in 247 peripheral blood samples. Samples were collected at "baseline level" without any cytostatic drugs exposure before recruiting or after at least 3 weeks without cytostatic drugs contact and at three times (cycle 1-3) post-exposure. Samples from 60 office employees served as controls. Furthermore, our results were compared to urinary analyses of cytostatic drugs (oxazaphosporines, anthracyclines, platinum) which were collected in parallel to the cytogenetic investigation. Statistical analyses were performed under consideration of age, gender and X-ray exposure. The frequency of micronuclei was significantly related to the age of the subjects (r(Spearman)=0.16; P<0.05). However, there were no significant differences in micronucleus rates between controls and exposed hospital workers. Similarly, micronucleus rates were not significantly different at the various sampling time points and there was no correlation between duration of employment and micronucleus rates. Furthermore, no correlation between current biomonitoring data of exposure (urine tests) and micronuclei frequency was found. Therefore, significantly increased genotoxic damage of the lymphocytes investigated in this study could not be demonstrated.

Antineoplastic Agents↗
PubMed2001

Association between urinary tract infection, renal damage and birth size.

UNLABELLED: The aim of this study was to investigate whether birth size is associated with permanent renal damage in children with urinary tract infection (UTI). A cohort of 1221 children under 16 y of age was diagnosed with their first symptomatic UTI between 1970 and 1979. Of these, 74 had urographic renal scarring in childhood and 57 were re-examined as adults. The birth files of 48 of these patients (35F, 13M) were available, and birthweight and birthlength in relation to gestational age were analysed and compared with a Swedish reference population. Children who had renal damage without vesicoureteric reflux were significantly smaller at birth (median weight, -0.76 SDS) compared with both children who had renal damage and reflux (median weight, -0.01 SDS) and the reference population. CONCLUSION: The demonstration of low birthweight among children with UTI and renal damage but no reflux suggests that low birthweight may be a risk factor for the development of renal damage.

Adolescent↗
PubMed2000

[Effect of monaural deprivation on maturation of the auditory pathway in the Mongolian gerbil (Meriones unguiculatus)].

Several investigations prove that monaural acoustic deprivation induces detrimental changes in the auditory pathway. So far the major interest focused on degenerative processes on the deprived side, while effects on the contralateral untreated side were not taken into consideration. This ontogenetic study investigates effects of early monaural acoustic deprivation on the functional development of the acoustically evoked auditory brainstem response (ABR) in the Mongolian gerbil. Young gerbils were deafened by a single intracochlear application of neomycin sulfate. The ABR development on the contralateral side differed in a late developmental period from that of normally hearing animals. These changes persisted until adulthood. Between day 55 and day 90 a significant 5 dB decrease of the ABR thresholds and a significant shortening of the interpeak latency II-V occurred. The results confirm that a complete monaural deprivation during the sensible or critical period leads on the contralateral side to plastic or compensatory changes in the auditory brainstem.

Age Factors↗
PubMed2000

[Using the Mongolian gerbil (Meriones unguiculatus) as an animal model in ontogenetic cochlear implant research].

One of the problems when providing prelingually deafened children with a cochlear implant is to find the optimal moment for the implantation in order to make optimal use of the sensitive phase in the maturation of the auditory system and to achieve the maximum improvement of hearing. Ontogenetic questions can be investigated in animal experiments under controlled conditions. In the present study an animal model (gerbil, Meriones unguiculatus) was established to simulate the situation of prelingually deafened children and to examine the influence of chronic electrostimulation on the development of the auditory pathway. We used species specific sounds for chronic stimulation to simulate significance of human language in our animal modell. A daily two-hour electrostimulation during the ontogenesis of early deafened animals lead to a partial compensation of the functional degeneration of the auditory pathway, which can be observed in totally deafened animals. This animal model provides an elaborate test design which can be used in CI research for the investigation of numerous problems.

Animals↗
PubMed1998

Molecular genetic characterization of the Philadelphia chromosome detected in reactor personnel highly exposed to radiation from the Chernobyl accident.

Clonal del(22q) chromosome aberrations were coincidentally observed in highly exposed reactor personnel of the Chernobyl power plant accident in the course of retrospective biological dosimetry. These aberrant chromosomes were detected in PHA-stimulated cultures from peripheral blood after FPG staining and revealed a morphology similar to a Philadelphia chromosome. A rearrangement of the BCR gene on 22q11 could be confirmed in unstimulated peripheral blood by RFLP analysis from three of four del(22q) carrying cases. FISH analysis of the del(22q) carrying cases with BCR- and ABL-specific DNA probes additionally exhibited a BCR-ABL fusion in 5.2 to 9% of cells in unstimulated blood. Breakpoints within the BCR gene could be located either in the M-bcr or the m-bcr region and thus, a specific breakpoint region could not be detected in these four patients. Since typical clinical leukemic symptoms associated with the translocation (9;22)(q24;q11) could not be observed in these highly irradiated subjects (1.1 to 5.8 Gy), the role of this particular aberration in the development of a radiation-induced leukemia remains obscure.

Chromosome Deletion↗
PubMed1997

Ontogeny of electrically evoked brain stem potentials in neonatally deafened gerbils (Meriones unguiculatus) after cochlear implantation.

To investigate the ontogeny of the electrically evoked auditory brainstem response (E-ABR) we used an animal model of neonatally deafened gerbils with an intracochlear implanted electrode. The E-ABR were recorded in three groups: normal hearing animals (NORM) and binaural deafened without chronical electrostimulation (BD) in comparison to binaural deafened animals with chronical stimulation (BDS). In group BD the deafening lead to inter-peak-latency II-V increase and histological degeneration in the Cochlear Nucleus. In chronical stimulated animals (BDS) we could not observe significant differences compared to unstimulated gerbils until the day after birth. In further studies longer stimulation periods, recordings of electrically evoked middle latency response as well as histological examinations of more central parts of the auditory pathway will be included.

Animals↗
PubMed1997

Meriones unguiculatus (Gerbil) as an animal model for the ontogenetic cochlear implant research.

The rehabilitation of prelingually deafened children using cochlear implants still raises several basic problems, e.g. growth of the skull and maturation of the auditory system. Systematic research in these problems requires a reliable animal model. The gerbil (Meriones unguiculatus) was investigated in respect of its suitability as an animal model for ontogenetic cochlear implant research. Gerbil pups were deafened by a single intracochlear application of neomycine on their 14th day after birth before the onset of natural hearing and implanted with an animal specific cochlea implant at day 30 after birth. To maintain the biological relevance the social sounds of gerbils were frequency transformed and used in daily electrostimulation until the 90th day after birth. As well established animal in hearing research the gerbil appears to be an appropriate animal model for ontogenetic cochlear implant research.

Animals↗
PubMed1996

Combined immunophenotyping and FISH with sex chromosome-specific DNA probes for the detection of chimerism in epidermal Langerhans cells after sex-mismatched bone marrow transplantation.

Langerhans cells (LC) of the skin represent bone marrow-derived dendritic antigen-presenting cells and are therefore important in pathophysiological processes such as rejection, graft-versus-host disease, and graft-versus-leukemia-reaction after bone marrow transplantation (BMT). For understanding of these diseases, the evaluation of the chimeric status of LC following BMT is of great interest. To analyze the sex chromosome constitution of LC in the skin, we established a modified and refined technique of combined immunophenotyping and fluorescence in situ hybridization (FISH) and investigated frozen sections of skin biopsies from nine patients after allogeneic sex-mismatched BMT and of two healthy donors for control. LC were specifically labeled using a fluorescent CD1 a antibody and hybridized simultaneously with X and Y chromosome-specific DNA probes. The results of this practical application on nine leukemia patients show the appearance of donor-type LC and the persistence of host-type LC at various times (36 up to 1395 days) after sex-mismatched BMT. Complete chimerism of LC could not be detected in any case. The frequency of recipient-specific LC ranged from 7% to 92% and showed no correlation with time postgrafting. We conclude from our results of 1461 analyzed LC that combined immunophenotyping and interphase cytogenetic analysis by FISH is the method of choice for the assessment of chimerism in a particular cell type after sex-mismatched BMT. Its practical application on other tissues affected by BMT-related pathophysiological processes reveals further knowledge of the time-dependent course of chimeric patterns after BMT.

Acute Disease↗
PubMed1989

Determination of vitamin D3 in margarines, oils and other supplemented food products using HPLC.

The vitamin D3 content of high fat foods, such as margarines and oils, was determined by liquid chromatography. The method involved sample saponification and an extraction process, in which the purification of the non-saponifiable matter was the critical step. A semi-preparative straight-phase clean up procedure was used to produce an adequately purified sample solution prior to the final analytical quantification step. Vitamin D2 was used as internal standard when estimating the vitamin D3 content. The overall recoveries depended on the fat content of the food sample and varied from 40% for margarines to 80% for low-fat products at a concentration of about 10 micrograms/100 g. The minimum detectable amount was 0.36 ng vitamin D3. The mean relative recovery of vitamin D3 in relation to vitamin D2 was calculated to be 0.97.

Animals↗
PubMed1987

High performance liquid chromatographic determination of cholecalciferol (vitamin D3) in food--a comparison with a bioassay method.

The vitamin D3 levels in fortified milk (0.5% fat) and other low fat products, such as infant formulas, porridges and gruels were determined chemically and biologically. The chemical method was based on a semi-preparative straight phase clean-up procedure, followed by an analytical reversed phase quantifying step. The biological tests were carried out using the curative x-ray method. The agreement between the results of the two method was good. The overall recoveries for the HPLC-method were 95% (SD = 2.8%, n = 13) at concentrations of 10 micrograms per 100 g and 5 micrograms per litre for fortified products and milk, respectively. The minimum detectable amount was 250 pg vitamin D3. The pre-vitamin D3 formation was studied during saponification conditions and the isomer ratio was estimated.

Animals↗
PubMedDate not supplied

A method for the induction of a cochlea-specific auditory deprivation in the gerbil (Meriones unguiculatus).

The neurophysiological effects of early electrical stimulation on the development and neural plasticity of the central auditory system in prelingually deafened children with cochlear implants are still unknown. Many of these basic questions can be answered systematically only in animal experiments. Meriones unguiculatus is a well-established animal model in hearing research. Deafening is produced by a single intracochlear application of an ototoxic aminoglycoside antibiotic (neomycin sulfate) on the 14th day after birth (DAB), i.e. before the late natural onset of hearing on the 16th DAB. A single application of the antibiotic abolishes auditory brainstem responses (ABR) to clicks completely and reduces sensitivity to low frequency tonebursts by 50 dB SPL. Scanning electron microscopy results show a destruction of the stereocilia of the inner and outer hair cells of the basal and medial cochlear turn and a reduction of those in the apical turn. Our method avoids a systemic application of antibiotics and can be used in studies dealing with the consequences of different forms of auditory deprivation, neuronal compensation processes or with ontogenetic studies and chronic electrostimulation in an animal model.

Acoustic Stimulation↗