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Biomedical subjects

G Beckmann

Publications and source records attributed to G Beckmann.

At least 19 recordsLinked to original sources

Multicenter field trial on possible health effects of toluene. I. Toluene body burdens in workers of the rotogravure industry.

Ambient air toluene concentrations as well as corresponding individual blood toluene levels were measured under conditions of a field trial, as basis for a correlation with possible acute effects. While the results of various psycho-physiological and medical evaluations after acute (Neubert et al., 2001) and long-term toluene exposure (Gericke et al., 2001) are published in accompanying papers, this publication deals with the exposure levels and body burdens characteristic of workers in the rotogravure industry in Germany at the time of the investigation (1993-1995). Besides providing some information on the exposure at various work-areas under occupational conditions, the correlation between a time-weighted average of the ambient air concentration with the corresponding blood toluene levels is analyzed. Limitations of such an attempt and possible pitfalls are discussed. In the largest field study so far performed on toluene exposure, 12 companies of the German rotogravure industry (and a total of 1528 volunteers) participated. Altogether, complete data sets, i.e. on both ambient air as well as blood toluene levels, were obtained from 1244 male and 124 female participants of the rotogravure industry with quite different degrees of toluene exposure. Rotogravure printers and their helpers were exposed to the highest toluene concentrations in ambient air. On the day of the evaluation, of 806 male volunteers within this group (of 1261 with verified exposure in air), 35 were exposed to a time-weighted average of 100 ppm (i.e. 375 mg/m(3)) or above, and 155 of the printers to concentrations between 50 and 100 ppm. Of the remaining 455 male participants of the rotogravure factories ('non-printers and helpers'), only three were exposed to toluene concentrations above 50 ppm. Only one of the 124 women working in the rotogravure factories was exposed to an average toluene concentrations above 100 mg/m(3) (i.e. 27 ppm). In 66 of the male volunteers toluene levels in blood of >850 microg/l were measured and 14 showed levels exceeding 1700 microg/l. When attempting to predict the resulting individual blood toluene levels from measurements of ambient air concentrations under field conditions, a considerable uncertainty is to be expected. We found a correlation coefficient of the regression curve of about 0.70, with numerous outliers (and a variation of the 12 factories between 0.52 and 0.88).

Adult↗

Multicenter field trial on possible health effects of toluene. II. Cross-sectional evaluation of acute low-level exposure.

Data on possible acute effects of today's relevant low-level exposure to toluene are contradictory, and information on possible effects of exposure under occupational conditions is largely lacking. In a controlled, multi-center, blinded field trial, effects possibly associated with acute toluene exposure were evaluated in workers of 12 German rotogravure factories. Medical examinations (inquiries on subjective symptoms, and standard tests of psycho-physiological and psycho-motor functions) were performed on almost 1500 volunteers, of whom 1290 were toluene-exposed (1178 men and 112 women), and about 200 participants served as references (157 men and 37 women), but the main aim of the trial was to reveal dose-response relationships. All volunteers were of the morning work-shift (6 h exposure). Both individual ambient air concentrations (time-weighted average) during the work-shift, as well as blood toluene concentrations after the work-shift were measured. Therefore, the medical data could for the first time be correlated with the actual individual body burden (blood toluene level) at the time of testing. In order to largely exclude confounding by chronic toluene exposure, kinetic measurements as well as the psycho-physiological and psycho-motoric tests were performed before and after the work-shift. Except for minor statistical deviations, neither convincing dose-dependent acute effects could be demonstrated with regression analyses in male volunteers at the exposure levels evaluated, nor were significant differences found when applying group statistics (highly toluene-exposed group versus volunteers with negligible exposure). Due to the rather large number of participants, the predictive power of the study is high, especially when compared with previous publications. In two psycho-physiological tests, a few more female volunteers with quite low toluene body burdens (<340 microg/l blood) showed relatively low scores when compared with participants of the reference group. Although evidence for a medical relevance is meager, the small numbers of participants, in both the exposure and the reference groups, hamper a reliable interpretation of the results concerning exposure levels above 85 microg toluene/l blood, and it is difficult to take confounding factors adequately into account. For the end points evaluated and under occupational conditions, neither blood toluene levels of 850 to 1700 microg/l (in the highest exposure group [EXPO-IV] with 56 participants), as measured 1/2 (+/-1/2) h after the work-shift, nor ambient air concentrations (time-weighted average over 6 h) between 50 and 100 ppm (188-375 mg/m(3)) were convincingly associated with alterations in psycho-physiological and psycho-motoric performances or increased the frequency of subjective complaints in male volunteers. For higher dose ranges of toluene exposure (i.e. >1700 microg toluene/l blood [or >100 ppm in ambient air]), our data set is too small for far reaching conclusions. Our data are insufficient for conclusions on a possibly higher susceptibility to toluene of some female workers. Results of kinetic studies and possible effects of long-term exposure are discussed in two accompanying publications (Neubert et al., 2001; Gericke et al., 2001).

Acute Disease↗

Multicenter field trial on possible health effects of toluene. III. Evaluation of effects after long-term exposure.

In rotogravure industry, contributing considerably to mass color printing of catalogues and magazines, toluene is still extensively used as paint solvent, and many printers have been exposed to this chemical for several decades. Information on adverse health effects associated with long-term toluene exposure is still controversial. In a multi-center study, adverse health effects possibly associated with long-term toluene exposure were evaluated. In 12 rotogravure factories, 1226 male volunteers were recruited, and sufficient information on exposure and on medical data was compiled for about 1077 of them. Evaluations included: physical examination, standard tests of psycho-physiological and psycho-motoric performances, self-report of subjective symptoms, and data on a variety of laboratory blood tests. The medical data were correlated with the length (months) of toluene exposure, and a rough estimate of the extent of exposure (i.e. highly exposed printers and their helpers versus employees working at locations with low or negligible toluene exposure). A small reference group (n=109) was selected from companies of the paper industry. When linear regression curves were calculated (test results versus duration of exposure), extremely low overall coefficients of determination (r(2) adj.) of a few percent were estimated within the data clouds, with sometimes statistically significant P-values. Closer analyses revealed a strong influence of the confounding factor age, no clustering of abnormal values of highly toluene-exposed volunteers, and the vast majority or all values of the highly and long-term toluene-exposed participants staying within the reference ranges. Thus, no medical relevance of P-values <0.05 could be recognized in this evaluation, and there may have been some border-line deviations or results largely occurring by chance in the large trial. In a small cluster of the many rotogravure printers toluene-exposed for more than 20 years, the highest systolic blood pressure values of the study were found, but many possible confounding factors were not taken into account. Data on acute exposure and possible effects are presented in accompanying papers (Neubert et al., 2001a, Neubert et al., 2001b). Restricting the conclusions to the end points evaluated as well as the apparent limitations of the evaluation, no evidence was found that long-term occupational toluene exposure extending over several decades in the rotogravure industry in the Western part of Germany was convincingly associated with chronic adverse health effects or convincingly altered surrogate markers in still working male volunteers. Several peculiarities and pitfalls arising when interpreting medical data associated with such a type of environmental exposure must be considered. Reversibility of alterations previously induced at higher levels of toluene-exposure, as well as a healthy workers effect, cannot be excluded for some of the medical end points evaluated.

Adult↗

The influence of the radicality of resection and dose of postoperative radiation therapy on local control and survival in carcinomas of the upper aerodigestive tract.

PURPOSE: To evaluate dose concepts in postoperative irradiation of carcinomas of the upper aerodigestive tract according to the radicality of resection. PATIENTS AND METHODS: In a retrospective analysis, the charts of 257 patients with histologically-proven carcinoma of the upper aerodigestive tract (40 T1, 80 T2, 53 T3, 84 T4 tumors, with nodal involvement in 181 cases) were reviewed according to the radicality of resection and dose of irradiation administered. Sixty-four patients had tumor-free resection margins (> 3 mm), 66 patients had close resection margins (< 3 mm), and 101 patients had R1 resections, and 26 patients had R2 resections. A median dose of 56 Gy was applied to the primary tumor bed and the cervical lymphatics (2 Gy/fraction, 5 fractions/week). In cases of R1 or R2 resection, or of close margins (< 3 mm), the tumor bed or, respectively, tumor residuals were boosted with doses up to a median of 66 Gy. Locoregional tumor control and survival was investigated by uni- and multivariate analyses according to T-, N-stage, grade of resection, total dose of radiation, and presence or absence of extracapsular tumor spread and lymphangiosis carcinomatosa. RESULTS: An overall 3- and 5-year survival rate of 60% and 45%, respectively, was achieved. Rates for freedom from locoregional recurrence were 77% and 72% at 3 and 5 years, respectively. The survival rates according to the grade of resection at 5 years were 67% for patients resected with tumor-free margins, 59% for patients resected with close margins, 26% for patients with R1 resection, and 27% for patients with R2 resection. Within a median follow-up period of 4.7 years for living patients, a total of 67 recurrences (26%) were observed (in 9% of patients resected with tumor-free margins, in 27% with close margins, in 37% of R1 resected, and in 19% of R2 resected patients). Freedom from locoregional recurrence at 3 years was achieved in 100% of the patients resected with tumor-free margins, in 92% of patients resected with close surgical margins, in 87% of R1 and 69% of R2 resected patients. In multivariate Cox-regression analysis, the variables grade of resection (p = 0.00031) and total dose of irradiation (p = 0.0046) were found as factors influencing locoregional control. Variables influencing survival according to multivariate analysis are T-stage (p = 0.0057), N-stage (p = 0.024), grade of resection (p = 0.000015), total dose of irradiation (p < 0. 000000). Extracapsular tumor spread and lymphangiosis carcinomatosa are factors of borderline significance (p = 0.055, p = 0.066). CONCLUSION: In postoperative radiotherapy of head and neck carcinomas, doses adapted to the risk of locoregional recurrent disease should be applied. Patients with R1 and R2 resections should be treated with doses of more than 68 Gy (2 Gy/fraction, 5 fractions/week) (with close margins [< 3 mm] more than 66 Gy) to achieve an improvement in locoregional control and survival.

Adult↗

Exhaustive mining of EST libraries for genes differentially expressed in normal and tumour tissues.

A four-step procedure for the efficient and systematic mining of whole EST libraries for differentially expressed genes is presented. After eliminating redundant entries from the EST library under investigation (step 1), contigs of maximal length are built upon each remaining EST using about 4 000 000 public and proprietary ESTs (step 2). These putative genes are compared against a database comprising ESTs from 16 different tissues (both normal and tumour affected) to determine whether or not they are differentially expressed (step 3; electronic northern). Fisher's exact test is used to assess the significance of differential expression. In step 4, an attempt is made to characterise the contigs obtained in the assembly through database comparison. A case study of the CGAP library NCI_CGAP_Br1.1, a library made from three (well, moderately, and poorly differentiated) invasive ductal breast tumours (2126 ESTs in total) was carried out. Of the maximal contigs, 139 were found to be significantly (alpha = 0.05) over-expressed in breast tumour tissue, while 13 appeared to be down-regulated.

Animals↗

Inactivating mutations and overexpression of BCL10, a caspase recruitment domain-containing gene, in MALT lymphoma with t(1;14)(p22;q32).

Mucosa-associated lymphoid tissue (MALT) lymphomas most frequently involve the gastrointestinal tract and are the most common subset of extranodal non-Hodgkin lymphoma (NHL). Here we describe overexpression of BCL10, a novel apoptotic signalling gene that encodes an amino-terminal caspase recruitment domain (CARD), in MALT lymphomas due to the recurrent t(1;14)(p22;q32). BCL10 cDNAs from t(1;14)-positive MALT tumours contained a variety of mutations, most resulting in truncations either in or carboxy terminal to the CARD. Wild-type BCL10 activated NF-kappaB but induced apoptosis of MCF7 and 293 cells. CARD-truncation mutants were unable to induce cell death or activate NF-kappaB, whereas mutants with C-terminal truncations retained NF-kappaB activation but did not induce apoptosis. Mutant BCL10 overexpression might have a twofold lymphomagenic effect: loss of BCL10 pro-apoptosis may confer a survival advantage to MALT B-cells, and constitutive NF-kappaB activation may provide both anti-apoptotic and proliferative signals mediated via its transcriptional targets.

Adaptor Proteins, Signal Transducing↗

Genomic organization of a 225-kb region in Xq28 containing the gene for X-linked myotubular myopathy (MTM1) and a related gene (MTMR1).

MTM1 is responsible for X-linked recessive myotubular myopathy, which is a congenital muscle disorder linked to Xq28. MTM1 is highly conserved from yeast to humans. A number of related genes also exist. The MTM1 gene family contains a consensus sequence consisting of the active enzyme site of protein tyrosine phosphatases (PTPs), suggesting that they belong to a new family of PTPs. Database searches revealed homology of myotubularin and all related peptides to the cisplatin resistance-associated alpha protein, which implicates an as yet unknown function. In addition, homology to the Sbf1 protein (SET binding factor 1), involved in the oncogenic transformation of fibroblasts and differentiation of myoblasts, was also evident. We describe 225 kb of genomic sequence containing MTM1 and the related gene, MTMR1, which lies 20 kb distal to MTM1. Although there is only moderate conservation of the exons, the striking similarity in the gene structures indicates that these two genes arose by duplication. Calculations suggest that this event occurred early in evolution long before separation of the human and mouse lineages. So far, mutations have been identified in the coding sequence of only 65% of the patients analyzed, indicating that the remaining mutations may lie in noncoding regions of MTM1 or possibly in MTMR1. Knowledge of the genomic sequence will facilitate mutation analyses of the coding and noncoding sequences of MTM1 and MTMR1.

Amino Acid Sequence↗

Characterization of naturally occurring myosin heavy chain antisense mRNA in rat heart.

Analysis of mRNA by Northern blot and reverse transcription-polymerase chain reaction demonstrated the expression of sense and considerable amounts of naturally occurring antisense mRNA for beta-myosin heavy chain (MHC) and alpha-MHC in the neonatal rat heart: antisense MHC mRNA expression of alpha-MHC and beta-MHC was approximately half of the corresponding sense MHC mRNA expression. Using a computational approach, we could identify a reverse Pol II promoter in the beta-MHC gene. Both sense and antisense MHC mRNA demonstrated similar sizes of approximately 6,000 bp in the Northern blot. Alpha-MHC antisense mRNA consisted of approximately 3,700 bp of complementary exon sequences and beta-MHC consisted of approximately 2,700 bp, suggesting a higher probability of alpha-MHC mRNA dimerization. Hence, sense mRNA transcripts and protein of alpha-MHC should exist at different relative levels in the neonatal state. In fact, the relative proportion of alpha-MHC was 52.0 +/- 2.6% on the sense mRNA but only 36.3 +/- 1.8% on the protein level. Because of its high abundance in the heart, we suggest that in the neonatal heart naturally occurring antisense mRNA may play a role in the regulation of MHC expression and, therefore, in the control of the energetical and contractile behaviour of the heart.

Aging↗

Mammalian protein homologous to VAT-1 of Torpedo californica: isolation from Ehrlich ascites tumor cells, biochemical characterization, and organization of its gene.

Recently, interest has focused on the human gene encoding the putative protein homologous to VAT-1, the major protein of the synaptic vesicles of the electric organ of the Pacific electric ray Torpedo californica, after it has been localized on chromosome locus 17q21 in a region encompassing the breast cancer gene BRCA1. Chromosomal instability in this region is implicated in inherited predisposition for breast and ovarian cancer. Here we describe isolation and biochemical characterization of a mammalian 48 kDa protein homologous to the VAT-1 protein of Torpedo californica. This VAT-1 homolog was isolated from a murine breast cancer cell line (Ehrlich ascites tumor) and identified by sequencing of cleavage peptides. The isolated VAT-1 homolog protein displays an ATPase activity and exists in two isoforms with isoelectric points of 5.7 and 5.8. cDNA was prepared from Ehrlich ascites tumor cells, and the murine VAT-1 homolog sequence was amplified by polymerase chain reaction and partially sequenced. The known part of the murine and the human translated sequences share 97% identity. By Northern blots, the size of the VAT-1 homolog mRNA in both murine and human (T47D) breast cancer cells was determined to be 2.8 kb. Based on the presented data, a modified gene structure of the human VAT-1 homolog with an extended exon 1 is proposed. VAT-1 and the mammalian VAT-1 homolog form a subgroup within the protein superfamily of medium-chain dehydrogenases/reductases.

Adenosine Triphosphatases↗

Nibrin, a novel DNA double-strand break repair protein, is mutated in Nijmegen breakage syndrome.

Nijmegen breakage syndrome (NBS) is an autosomal recessive chromosomal instability syndrome characterized by microcephaly, growth retardation, immunodeficiency, and cancer predisposition. Cells from NBS patients are hypersensitive to ionizing radiation with cytogenetic features indistinguishable from ataxia telangiectasia. We describe the positional cloning of a gene encoding a novel protein, nibrin. It contains two modules found in cell cycle checkpoint proteins, a forkhead-associated domain adjacent to a breast cancer carboxy-terminal domain. A truncating 5 bp deletion was identified in the majority of NBS patients, carrying a conserved marker haplotype. Five further truncating mutations were identified in patients with other distinct haplotypes. The domains found in nibrin and the NBS phenotype suggest that this disorder is caused by defective responses to DNA double-strand breaks.

Amino Acid Sequence↗

Merging extracellular domains: fold prediction for laminin G-like and amino-terminal thrombospondin-like modules based on homology to pentraxins.

Using a new method for construction and database searches of sequence consensus strings, we have identified a new superfamily of protein modules comprising laminin G, thrombospondin N and the pentraxin families. The conserved patterns correspond mainly to hydrophobic core residues located in central beta strands of the known three-dimensional structures of two pentraxins, the human C-reactive protein and the serum amyloid P-component. Thus, we predict a similar jellyroll fold for all members of this superfamily. In addition, the conservation of two exposed aspartate residues in the majority of superfamily members suggests hitherto unrecognised functional sites.

Amino Acid Sequence↗

Phase I trial of adoptive immunotherapy of cancer patients using monocyte-derived macrophages activated with interferon gamma and lipopolysaccharide.

Cells of the monocyte/macrophage lineage have shown antitumor activity in vitro and in murine models after activation with interferon (IFN) gamma. In vitro data suggest an additional effect on macrophage antitumor activity when IFN gamma is combined with endotoxin (lipopolysaccharides; LPS). In this study we treated nine cancer patients with a total of 62 MAK infusion cycles with autologous macrophages given intravenously (i.v.) after in vitro activation with IFN gamma and LPS. Low-grade fever (WHO I/II) was the commonest side-effect. Chills, nausea, and headache were noted when the number of transfused macrophages exceeded 2 x 10(8). One WHO IV toxicity occurred, consisting of hypotension after transfer of 3 x 10(8) cells, defining this dose as the maximum cell number tolerated. After pretreatment with ibuprofen, however, the maximum cell number could be increased without reaching dose-limiting toxicity. The highest number of cells reinfused was 15 x 10(8). Circulating interleukin(IL)-6 increased in a dose-dependent manner as did IL-1 receptor antagonist (IL-1RA) and IL-8. Tumor response consisted of one case of stable disease (12 weeks) in a patient with formerly progressing colorectal cancer and progressive diseases in eight patients. This study indicates that reinfusion of autologous LPS-activated macrophages upon pretreatment with ibuprofen is feasible and tolerated without major side-effects.

Antithrombins↗

Self-organizing hierarchic networks for pattern recognition in protein sequence.

We present a method based on hierarchical self-organizing maps (SOMs) for recognizing patterns in protein sequences. The method is fully automatic, does not require prealigned sequences, is insensitive to redundancy in the training set, and works surprisingly well even with small learning sets. Because it uses unsupervised neural networks, it is able to extract patterns that are not present in all of the unaligned sequences of the learning set. The identification of these patterns in sequence databases is sensitive and efficient. The procedure comprises three main training stages. In the first stage, one SOM is trained to extract common features from the set of unaligned learning sequences. A feature is a number of ungapped sequence segments (usually 4-16 residues long) that are similar to segments in most of the sequences of the learning set according to an initial similarity matrix. In the second training stage, the recognition of each individual feature is refined by selecting an optimal weighting matrix out of a variety of existing amino acid similarity matrices. In a third stage of the SOM procedure, the position of the features in the individual sequences is learned. This allows for variants with feature repeats and feature shuffling. The procedure has been successfully applied to a number of notoriously difficult cases with distinct recognition problems: helix-turn-helix motifs in DNA-binding proteins, the CUB domain of developmentally regulated proteins, and the superfamily of ribokinases. A comparison with the established database search procedure PROFILE (and with several others) led to the conclusion that the new automatic method performs satisfactorily.

Amino Acid Sequence↗

[Anthropology of the father role].

The anthropological basic characteristics of the "father role" are presented by means of biological and early cultural aspects. The "father role" in its origin arose from mothercentered groups. For them only the "social fatherhood" was of any importance. The female primary groups accepted that man as being "the father" who could provide maximum protection for mother and children. It was not until the post ice-age extinction of many wild animals and the transition to owning of domestic animals--the capital of the shepherds--that patriarchy did develop. Now the "biological fatherhood" as a means of controlling female fertility changed to be the focal point within euroasian cultures.

Animals↗

Interleukin 1 beta enhances the response of rabbit synovial fibroblasts in vitro to dexamethasone injury: implication for the role of increased nuclear hypersensitive sites and the number of dexamethasone receptors.

OBJECTIVE: As a model system to understand the efficacy of patients with glucocorticoid (GC) treatment of joint inflammation of rheumatoid arthritis, we stimulated confluent rabbit synovial fibroblasts in culture with interleukin 1 beta (IL-1 beta) and studied the effects of dexamethasone (Dex). METHODS: Twenty-four h after IL stimulation Dex was added and the response of cells to Dex was estimated by [3H]thymidine uptake, cell count and lactate dehydrogenase release. Cellular and nuclear binding of [3H] Dex as well as the DNase sensitivity of isolated nuclei were estimated. RESULTS: Dex strongly inhibited the [3H]thymidine uptake by the stimulated cells in a dose dependent manner with Ki of lower than 10(-12) M, whereas it only slightly inhibited the unstimulated cells. With stimulation the sensitivity of cells increased 10-fold as estimated by lactate dehydrogenase release and 85-fold by counting the final cell density. We found also a 5-fold increase in the DNase I hypersensitive sites in the nuclei and a 2 to 3-fold increase in the cellular as well as the nuclear Dex binding sites following stimulation. CONCLUSION: In addition to the well documented inhibition of degradative enzyme production by the stimulated synovium, the efficacy of GC treatment of patients could be explained also on the basis of the sensitization of stimulated synovium to the GC mediated injury.

Animals↗

The CUB domain. A widespread module in developmentally regulated proteins.

Sequence analysis has revealed the presence of 31 copies of an extracellular domain, here called CUB, in 16 functionally diverse proteins such as the dorso-ventral patterning protein tolloid, bone morphogenetic protein 1, a family of spermadhesins, complement subcomponents Cls/Clr and the neuronal recognition molecule A5. Most of them are known to be involved in developmental processes. Our analysis of this new family includes the identification of seven previously undescribed members, the characterization of conserved features and a topology prediction of this approximately 110 residue spanning domain, which suggests an antiparallel beta-barrel similar to those in immunoglobulins.

Amino Acid Sequence↗

3-aminobenzamide protects the mouse thymocytes in vitro from dexamethasone-mediated apoptotic cell death and cytolysis without changing DNA strand breakage.

Exposure of mouse thymocytes to 1 microM dexamethasone (Dex) resulted in a dramatic increase in the degree of DNA strand breakage up to 80% between 4 to 6 h postincubation. During incubation a marked decrease in the number of total and viable cells as well as an increase in the release of lactate dehydrogenase into medium were detectable, indicating a strong cytotoxicity of Dex on the mouse thymocytes. Agarose gel electrophoresis of DNA from cells exposed to Dex for 6 h clearly demonstrated an increased laddering of DNA fragments multiple of approx. 200 base pairs as a characteristic feature of an apoptosis or programmed cell death. The cytotoxicity of Dex, as judged by the decrease in the viability and increase in the cell lysis, was effectively prevented by 3-aminobenzamide, a potent inhibitor of poly(ADP-ribose) synthesis. Furthermore, the lowering of intracellular NAD levels, which was observable in the present study most probably as a result of activation of poly(ADP-ribose) synthesis due to Dex-mediated DNA strand breakage, was also specifically prevented by the inhibitor, although the DNA strand breakage itself was not affected under these conditions. Our present results indicate that the Dex-mediated thymocyte death and cytolysis and probably intrathymic apoptotic thymocytolysis could be attributable primarily to the loss of intracellular NAD.

Animals↗