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Biomedical subjects

N Becker

Publications and source records attributed to N Becker.

At least 73 records · Page 4Linked to original sources
PubMed1994

Several receptor tyrosine kinase genes of the Eph family are segmentally expressed in the developing hindbrain.

Pattern formation in the hindbrain involves a segmentation process leading to the formation of metameric units, manifested as successive swellings known as rhombomeres (r). In search for genes involved in cell-cell interactions during hindbrain segmentation, we have screened for protein kinase genes with restricted expression patterns in this region of the CNS. We present the cloning of three novel mouse genes, Sek-2, Sek-3 and Sek-4 (members of the Eph subfamily of putative transmembrane receptor protein tyrosine kinases (RTKs)), the identification of their chromosomal locations, and the analysis of their expression between 7.5 and 10.5 days of development. Before morphological segmentation, Sek-2 is transcribed in a transverse stripe corresponding to prospective r4 and the adjacent mesoderm, suggesting possible roles both in hindbrain segmentation and signalling between neuroepithelium and mesoderm. Sek-3 and Sek-4 have common domains of expression, including r3, r5 and part of the midbrain, as well as specific domains in the diencephalon, telencephalon, spinal cord and in mesodermal and neural crest derivatives. Together with our previous finding that Sek (Sek-1) is expressed in r3 and r5 (Gilardi-Hebenstreit et al., 1992; Nieto et al., 1992), these data indicate that members of the Eph family of RTKs may co-operate in the segmental patterning of the hindbrain.

Amino Acid Sequence↗
PubMed1994

Cancer mapping: why not use absolute scales?

Cancer atlases frequently use relative scales which rank regional mortality rates relative to the countrywide mean (if relative risks are used) or median (if percentile colour schemes are used). This method has various disadvantages which limit comparability and interpretation. An alternative is absolute scaling which is well-known from geographic atlases: the natural rank order of altitudes is mapped into a colour scheme which is preserved over all maps of an atlas. Applied to cancer atlases this means that the different magnitudes of mortality for different cancer sites and sexes is preserved and leads to the use of different ranges of a relatively wide common colour scheme. This technique is applied to the data of the German Cancer Atlas published in 1984. Its properties are outlined and it is shown that it overcomes many of the unfavourable characteristics of the convenient procedures.

Atlases as Topic↗
PubMed1994

Mellow and frenetic antecedent music during athletic performance of children, adults, and seniors.

Previous research has yielded a contradictory picture of the effects of music on athletic performance. While athletes frequently report using music while training or during or before an event, laboratory studies have generally not detected a beneficial effect of music. The influence of music, judged mellow and frenetic, played before exercise was assessed by measuring stationary bicycle mileage. 60 volunteers from three age groups (child, adult, and senior) and with two levels of prior activity (high and low) were subjects. Each participant received three randomized 2-min. exercise trials, each preceded by 1-min. exposure to mellow music, frenetic music, or white noise. Mileage in both music conditions was significantly higher than that during the white-noise control trial except among the senior subjects. No significant differences between frenetic and mellow music were noted.

Adolescent↗
PubMed1994

Protocol for the introduction of new Bacillus thuringiensis Israelensis products into the routine mosquito control program in Germany.

The efficacy of new and frequently used formulations of Bacillus thuringiensis israelensis (B.t.i.) has been evaluated in the laboratory and in the field conditions under which they will be used in Germany. The principles governing the successful introduction of new formulations of microbial control agents into routine programs have been highlighted. The potency of the formulations in use (Teknar, Bactimos, and Vectobac) and their efficacy against the indigenous mosquito species Aedes vexans, Aedes cantans, and Culex pipiens have been assessed to determine the minimum effective dosage in the laboratory and the optimum effective dosage in small field trials. These results should ensure the proper selection of the most appropriate formulation and dosage for the particular climatic and ecological conditions.

Aedes↗
PubMed1994

Efficacy of Clostridium bifermentans serovar Malaysia on target and nontarget organisms.

Clostridium bifermentans serovar malaysia (C.b.m.) is highly toxic to mosquito larvae. In this study, the following aquatic nontarget invertebrates were treated with high C.b.m. concentrations (up to 1,600-fold the toxic concentration for Anopheles stephensi) to study their susceptibility towards the bacterial toxin: Planorbis planorbis (Pulmonata); Asellus aquaticus (Isopoda); Daphnia pulex (Cladocera); Cloeon dipterum (Ephemeroptera); Plea leachi (Heteroptera); and Eristalis sp., Chaoborus crystallinus, Chironomus thummi, and Psychoda alternata (Diptera). In addition, bioassays were performed with mosquito larvae (Aedes aegypti, Anopheles stephensi, and Culex pipiens). Psychoda alternata larvae were very susceptible, with LC50/LC90 values comparable to those of mosquito larvae (about 10(3)-10(5) spores/ml). The tests with Chaoborus crystallinus larvae showed significant mortality rates at high concentrations, but generally not before 4 or 5 days after treatment. The remaining nontarget organisms did not show any susceptibility. The investigation confirms the specificity of C.b.m. to nematocerous Diptera.

Aedes↗
PubMed1994

Cigarette smoking and lung cancer: a reconsideration of the British doctors' data with cumulative damage models.

Cumulative damage models are a macroscopic approach to describe the epidemiologic aspects of carcinogenesis. This approach is based on the conjectures that cancer epidemiology (a) may derive only limited insight into specific biologic processes, and (b) may need no detailed biologic assumptions to obtain sufficient understanding of the relation between environmental exposures and host responses in human populations. The cumulative damage model leads intrinsically to the theoretical interpretation of the epidemiologic aspects of carcinogenesis as a kind of wear-out process. In the present paper, it has been applied to the data of the British physicians' study and is contrasted with some other convenient models. The comparisons show that all considered models fit the data reasonably well. The conclusion is essentially theoretical: because the present model fits the data sufficiently closely, but is based on rather parsimonious biologic assumptions, the specific referral of epidemiologic observations to cellular events, as done by other approaches, might be an overinterpretation of the data.

Adult↗
PubMed1993

Infusional cyclophosphamide, doxorubicin, and etoposide in human immunodeficiency virus- and human T-cell leukemia virus type I-related non-Hodgkin's lymphoma: a highly active regimen.

Fourteen patients with poor-prognosis intermediate- to high-grade non-Hodgkin's lymphoma (NHL) associated with human immunodeficiency virus (HIV) infection (12 patients) or human T-cell leukemia virus type I (HTLV-I) infection (two patients) received cyclophosphamide 750 mg/m2, doxorubicin 50 mg/m2, and etoposide 240 mg/m2 administered as a continuous intravenous (IV) infusion over 4 days (infusional CDE); treatment was repeated every 28 or more days for up to six cycles. All HIV-positive patients had at least one poor prognostic feature, which included either extranodal disease (10 patients), Karnofsky performance status less than 70% (six patients), a CD4 count less than 100/microL (six patients), or a prior history of acquired immunodeficiency syndrome (AIDS; one patient). Both HTLV-I-positive patients had an elevated serum lactate dehydrogenase (LDH) level, a poor prognostic feature in that setting. Complete response (CR) occurred in 10 patients (71%; 95% confidence interval, 48% to 95%) and partial response (PR) occurred in three patients (21%), yielding an overall objective response rate of approximately 93%. The estimated Kaplan-Meier median survival was 17.4 months; seven of 12 HIV-positive patients are alive and disease-free with a median follow-up of 15 months (range, 7 to 24 months). Hospitalization was required after 19% of treatment cycles due to fever associated with granulocytopenia. Documented or suspected opportunistic infection occurred in five patients (36%), bacteremia occurred in three patients (21%), and candidemia occurred in one patient (7%). There was one treatment-related death attributable to disseminated aspergillosis. This pilot study suggests that infusional CDE may be a highly active regimen capable of producing durable remissions in a high proportion of patients with HIV-related NHL. Further study is required to confirm this observation.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Increased risk of acute myelogenous leukemia (AML) and chronic myelogenous leukemia (CML) in a county of Hesse, Germany.

The incidence of acute and chronic myelogenous leukemia has been compared for the two neighbouring regions of Marburg and Giessen in Hesse (Germany). The investigation was based on the incident cases of the years 1983-1989 which have been diagnosed in the hematological departments of the universities of the two regions. The epidemiological evaluation of the data has been carried out in terms of a historical follow-up study, and shows an increased relative risk for the region around Marburg with a particular elevation for one community within this region. Potential determinants are discussed and focus on trinitrotoluene (TNT) and decomposition products which are known to contaminate the soil of this community, in some places severely, due to insufficient removal of remnants of the TNT production in large underground plants during World War II.

Adult↗
PubMed1993

[Molecular analysis of the development of the rhombencephalon].

Hindbrain development involves a segmentation process which in particular governs cranial-motor nerves organization. We have initiated a molecular analysis of this morphogenetic process by searching for genes expressed in specific hindbrain segments (rhombomeres). We have identified a gene encoding a transcription factor, Krox-20, which is specific of rhombomeres 3 and 5 and several genes encoding receptor tyrosine kinases which are also segment-specific. The study of Krox-20 has allowed the identification of its nucleotide target, the localization of the functional domains of the protein and the demonstration of its involvement in the transcriptional activation of the Hoxb-2 gene and in the control of normal hindbrain development.

Animals↗
PubMed1993

Investigations on possible resistance in Aedes vexans field populations after a 10-year application of Bacillus thuringiensis israelensis.

In the Upper Rhine Valley (Germany), Bacillus thuringiensis var. israelensis has been widely used against floodwater mosquitoes over an area of approximately 500 km2 for more than 10 years. The susceptibility of larvae of Aedes vexans field populations in 3 untreated (Lake Constance) and 3 treated areas (Upper Rhine Valley) was assessed by means of bioassays with B.t.i. (Bactimos WP, 6,000 AAU/mg), following WHO guidelines. Log-probit analyses and statistical evaluations of the data showed that the LC50 values as well as slopes of bioassays of the larvae deriving from the different areas showed no significant differences. Two populations in the treated area were even more susceptible than populations from the untreated areas. These results have been confirmed by resistance ratios, which were less than one in all tests carried out.

Aedes↗
PubMed1992

Medical risk factors and the development of brain tumors.

Several diseases and medical treatments are discussed as risk factors for the development of brain tumors. A population-based case-control study in the Rhein-Neckar-Odenwald area (containing 1.3 million inhabitants) of Germany was established to investigate this question. A total of 226 patients (cases) with primary brain tumors (International Classification of Diseases, ninth edition, classes 191, 191.1, and 192.0) and 418 control subjects (controls) were interviewed using a standardized questionnaire over a period of 2 years. No association was seen for head injuries, hereditary diseases, family history, and radiographic examination of the head and teeth. However, more cases than controls had had meningitis (relative risk [RR], 2.7; 95% confidence interval [CI], 0.9 to 8.6) or epilepsy (RR, 2.6; 95% CI, 0.6 to 11.7). The RR was decreased for those who had allergic diseases (RR, 0.7; 95% CI, 0.5 to 1.0), diabetes (RR, 0.7; 95% CI, 0.3 to 1.8), and infections and colds (RR, 0.3; 95% CI, 0.1 to 0.8).

Adult↗
PubMed1992

Fitting cancer mortality data with cumulative damage models.

Cumulative damage models conceive the epidemiologically observed aspects of carcinogenesis as some kind of total balance over a complex biological process and suggest that this total balance might behave as a wear-and-tear process. The essential concepts of this mechanistic model are exposure to a carcinogenically damaging environment and resistance of a host system against those damages. Intensity of exposure and magnitude of host resistance are the parameters to be assessed. The paper describes (1) the statistical methods for fitting this model to birth cohort data; (2) for which cancer sites the model provides acceptable fits and for which it does not; and (3) how model extensions provide improvements in the goodness of fit. It is shown that from a theoretical viewpoint the consideration of extra-Poisson variation is needed for descriptive epidemiological applications. The practical examples indicate that the present version of the model provides acceptable fits for only a few cancer sites and that refinements are needed in the majority of sites. However, plausible model extensions suggest considerable improvements of goodness of fit.

Carcinogens↗
PubMed1992

Factors influencing the activity of Bacillus thuringiensis var. israelensis treatments.

Environmental factors influence the effectiveness of microbial control agents in mosquito control programs. Four of these factors (water temperature, larval density, sunlight and the effect of associated filter feeders) were studied with Bacillus thuringiensis var. israelensis under laboratory and semifield conditions in Europe using different instars of Aedes vexans, Ae. aegypti and Culex pipiens. Bioassays conducted at a low temperature (5 degrees C) yielded 10-fold higher LC50 and LC90 values compared with those conducted at a high temperature (25 degrees C). The efficacy of B.t.i. decreased in a linear manner with increasing larval density. Sunlight can reduce the effectiveness of B.t.i. by several times. Competition in food intake by filter feeding Daphnia resulted in lower mortality of mosquito larvae after B.t.i. applications.

Aedes↗
PubMed1992

Follow-up study among model and pattern makers in an automobile company in the Federal Republic of Germany.

The follow-up of a cohort of 528 model makers and a control group of 2273 tool makers shows an unusual pattern of mortality in the model makers' cohort. In contrast to the usual ranking, malignant neoplasms are the most frequent group of cause of death followed by diseases of the cardiovascular system. The rate ratio (RR) for malignant tumors is significantly increased among model makers compared with tool makers RR = 1.8, (95% confidence level [CL] = 1.3-2.7). The sites affected by excess cancer were stomach, the genitourinary organs, and the brain. In contrast to other studies, no tumors of the large intestine have been observed. Furthermore, there is a remarkable underrepresentation of tumors of the respiratory organs. Because these results are based on a rather small number of cases, further follow-up of the cohort is warranted to draw more profound conclusions.

Adolescent↗
PubMed1992

The Diet Habit Survey: a new method of dietary assessment that relates to plasma cholesterol changes.

The Diet Habit Survey was designed to identify eating habits and measure dietary changes made over time by 442 adults in the Family Heart Study, a coronary heart disease prevention project. Reliability was determined by test-retest analysis. Validity was assessed by comparison with 24-hour dietary recalls and by comparing changes in diet with changes in plasma cholesterol levels. At baseline, 89% of the subjects were classified as eating the current American diet (37% fat), 10% reported eating Diet 1 (30% fat), and 1% reported eating Diet 2 (25% fat). After 5 years of dietary intervention, the population's eating habits had shifted; 48% reported eating the current American diet, 37% reported Diet 1, 14% reported Diet 2, and 1% reported Diet 3 (20% fat). Significant plasma cholesterol lowering was associated with changes in Diet Habit Survey scores reflecting lower cholesterol and saturated fat and higher complex carbohydrate intakes. This questionnaire is an inexpensive, reliable, and valid instrument for rapid assessment of eating habits and diet composition and, thus, is an important new tool for dietetics researchers and practitioners.

Adult↗
PubMed1991

Common infections in the history of cancer patients and controls.

The association between the frequency of manifest infectious diseases and cancer risk was investigated in a case-control study at Heidelberg, FRG. A total of 255 cases with carcinomas of the stomach, colon, rectum, breast, and ovary, as well as 255 population controls and 230 hospital controls were interviewed using a standard questionnaire. Controls were matched to the cases for age, sex, and region of residence at the time of the interview. A history of common colds or gastroenteric influenza prior to the interview was found to be associated with a decreased cancer risk. Thus the odds ratios for "three or more common colds per year (on average)" versus "no common cold within the last 5 years prior to the interview" were 0.18 (95% CI = 0.05-0.69) and 0.23 (95% CI = 0.06-0.89) relative to population controls and hospital controls, respectively. There was no apparent relationship between childhood infections or other diseases reported in the earlier history, and cancer risk. While the findings are supported by previous studies and fit well into the results of other fields of cancer research, a conclusive interpretation and biological explanation cannot yet be given.

Adult↗