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Biomedical subjects

J Schiemann

Publications and source records attributed to J Schiemann.

27 records · Page 2Linked to original sources

Operational evaluation of the EXEMSI project. Experimental Campaign for the European Manned Space Infrastructure.

In general the EXEMSI project has proved to be very successful mission. It has demonstrated that it is indeed possible to perform a major and useful project in a short time and on a moderate budget. In addition to achieving the scientific objectives, this simulation project provided valuable experience in the training of members of chamber crew and ground control crew for their tasks. It covered all aspects of a mission from call for experiment proposals, crew selection and training, integration and testing of the facility and its equipment, to daily monitoring and managing of the mission, and finally post-isolation data collection and evaluation. These other activities were accomplished by a small team of experts in the astoundingly short time of 8 months. What was lacking in manpower, time and funds, was more than made up for by enthusiasm, expertise, team spirit, hard work and long hours well beyond the call of duty of all those involved. In addition to the specific and technological objectives reached, many lessons learned in this operation have been identified, which could help to improve future missions. The experience has shown pitfalls to be avoided in future mission, as well as points where some small increase in effort can make a considerable difference. With the prospect of long-term manned spaceflights looming in the near future and the ever increasing costs of such endeavors, the possibilities offered by running simulated missions on the ground should be seriously considered. Such simulations permit the study of scientific and operational aspects of a space mission prior to its actual implementation. A ground based simulation of an extended space mission may be run at a fraction of the cost of an in-orbit precursor mission of even one-week duration. However, careful planning of the simulation mission is required so that it may yield relevant information and useful experience. Lessons learned from the EXEMSI project should be taken into account in such planning. At the start clear goals should be formulated, that can provide clear guidelines for building up the infrastructure and defining the operational scenario. A long duration mission simulating the conditions on the Russian space station MIR could provide a valuable source of information and experience in preparing for the MIR '95 Mission.

Astronauts↗

[Effectiveness and tolerance of combined verapamil retard and hydrochlorothiazide. Results of a double-blind, randomized study].

AIM: To determine, in a multicenter study, whether the fixed combination of verapamil retard (240 mg) and hydrochlorothiazide (12.5 mg) is capable of lowering blood pressure more effectively than either of the substances alone or placebo, while retaining good tolerability. METHOD: A total of 173 patients who, after a four-week run-in period had a diastolic blood pressure of at least 100 and not more than 115 mm Hg, were randomized to six weeks of monotherapy with one of the two substances, placebo or the fixed combination. RESULTS: Combination treatment proved superior to monotherapy with either substance in lowering the diastolic blood pressure (p < 0.05). Also in terms of normalization (diastolic pressure < 90 mm Hg) the combination was clearly superior (p < 0.05). During the study no side effects beyond those associated with the single substances, occurred.

Adult↗

Molybdenum co-factor biosynthesis: the Arabidopsis thaliana cDNA cnx1 encodes a multifunctional two-domain protein homologous to a mammalian neuroprotein, the insect protein Cinnamon and three Escherichia coli proteins.

The molybdenum co-factor (Moco) is an essential part of all eukaryotic molybdoenzymes. It is a molybdopterin and reveals the same principal structure in eubacteria, archaebacteria and eukaryotes. This paper reports the isolation of cnx1, a cDNA clone of Arabidopsis thaliana which complements the Escherichia coli Moco mutant mogA. The mapping data of this cDNA correlate well with the mapping position of the A. thaliana molybdenum co-factor locus chl6. As mutants in chl6 are known to be repairable by high concentrations of molybdate, the defective gene is very likely to be involved in the last step of Moco biosynthesis, that is, the insertion of molybdenum into molybdopterin. The protein encoded by cnx1 shows a two-domain structure: the N-terminal domain is homologous to the E. coli Moco protein MoeA, the C-terminal domain is homologous to the E. coli Moco proteins MoaB and MogA, respectively. These homologies show that part of the prokaryotic Moco biosynthetic pathway accomplished by monofunctional proteins in E. coli, is performed by a single multifunctional protein in eukaryotes. In addition Cnx1 is homologous to the eukaryotic proteins Gephyrin, a rat neuroprotein, and Cinnamon, a Drosophila protein with a function in Moco biosynthesis. These proteins also show a two-domain structure but the order of the domains is inversed as compared with Cnx1. Southern analysis indicates the existence of at least one further member, in addition to the cnx1 gene, of this novel gene family in the Arabidopsis genome.

Amino Acid Sequence↗

Stress and activity of molybdenum-containing complex (molybdenum cofactor) in winter wheat seeds.

Molybdenum, applied in vivo, restored the damage from low temperature with winter wheat (Triticum aestivum, var "Sadovo 1") grown on acid soil and, in addition, sharply increased productivity (G Salcheva, D Georgieva, 1982; G Salcheva et al., 1977, 1979). Two fractions with molybdenum-cofactor activity in seeds were detected. One of them has a molecular weight of about 230 kilodaltons corresponding to xanthine oxidase activity and leaf nitrate reductase activity. The other has a molecular weight of about 60 kilodaltons. The ratio between the molybdenum-cofactor activity of these fractions was different in ;mother' seeds used in the experiment, in seeds obtained from the damaged plants, and in seeds obtained from the damaged plants restored by in vivo molybdenum addition. Every one of these fractions consisted of several components in which molybdenum-cofactor activity and stability in vitro was different. We suggest that plants store molybdenum as molybdenum carriers in these low molecular weight fractions.

Journal Article↗

High meiotic stability of a foreign gene introduced into tobacco by Agrobacterium-mediated transformation.

Two lines of transgenic Nicotiana tabacum transformed to kanamycin resistance by means of a binary Agrobacterium vector containing a nos-npt gene were investigated over three generations. Southern hybridization and crossing analyses revealed that a single copy of T-DNA had integrated in each line and that the kanamycin resistance was regularly transmitted to the progeny as a monogenic dominant trait. Homozygous transgenic plants were fully fertile, morphologically normal and did not significantly differ from wild-type plants in the quantitative characters examined (plant height, flowering time). The two lines showed very low, but significantly different levels of meiotic instability: kanamycin-sensitive plants occurred among backcross progeny from homozygous transgenic plants with frequencies of 6/45,000 and 25/45,000, respectively. The sensitive plants arose independently of each other and thus resulted from meiotic rather than mitotic events. These findings demonstrate for the first time that integrated foreign genes can be transmitted to progeny with the high degree of meiotic stability required for commercial varieties of crop plants. They emphasize the importance of non-homologous integration and of avoiding co-integration of inactive gene copies for achieving meiotically stable transformants.

Genetic Vectors↗

A binary vector for transferring genomic libraries to plants.

The transformation of mutant plants with a complete recombinant library derived from wild-type DNA followed by assay of transformed plants for complementation of the mutant phenotype is a promising method for the isolation of plant genes. The small genome of Arabidopsis thaliana is a good candidate for attempting this so-called shotgun transformation. We present the properties of an A. thaliana genomic library cloned in a binary vector, pC22. This vector, designed to introduce genomic libraries into plants, contains the oriV of the Ri plasmid pRiHR1 by which it replicates perfectly stably in Agrobacterium. Upon transfer of the library from E. coli to A. tumefaciens large differences in transfer efficiencies of individual recombinant clones were observed. There is a direct relation between transfer efficiency and stability of the recombinant clones both in E. coli and A. tumefaciens. The stability is independent of the insert size, but seems to be related to the nature of the insert DNA. The feasibility of shotgun transformation and problems of statistical sampling are discussed.

Cloning, Molecular↗

Electrocorticography: information derived from intraoperative recordings during seizure surgery.

The findings of 100 consecutive electrocorticographies in 94 epileptic patients were reviewed. Most of these patients underwent temporal lobectomies. A well defined and circumscript cortical spike focus was found in only 28 tracings whereas multiple sub-foci of spike activity or dissipated areas of spiking were demonstrated in 46 recordings. Cortical spike activity was minimal in 14 and absent in 12 tracings. Additional one-lead depth electrodes (inserted mainly into amygdala and hippocampus) yielded rather little information in contrast to the wealth of information derived from chronic multiple-leads depth implants prior to surgery. The frequent occurrence of dissipated spike foci suggests that, in partial epilepsies (and especially in temporal lobe epilepsy), epileptogenic zones are more widespread than one would expect from the scalp EEG recordings. These findings lend support to the use of en-bloc removal of large portions of an affected lobe.

Adolescent↗

[Multicenter long-term study of gallopamil in patients with coronary heart disease].

Efficacy and tolerance of gallopamil (Procorum) were investigated over a period of 1 year under practice conditions in a total of 455 patients (254 male, 201 female), aged 62 years (male) and 66 (female) on an average, with electrocardiographically confirmed coronary heart disease. The most frequently applied dosage was 1 film-coated tablet of gallopamil 50 mg 2-3 times daily. Frequency of attacks and nitro consumption as criteria of efficacy decreased by an average of approx. 80% in comparison to the placebo period. Full effectiveness was usually reached 4 weeks after start of therapy. ST-depression under exercise diminished by approx. 50%. An improved exercise tolerance was likewise observed, especially in patients who only tolerated up to 100 Watt prior to therapy. Therapeutic success was defined as good in 73% of the cases, satisfactory in 17.3% and insufficient in 6.7% by the trial physicians - the patient's opinion also being taken into consideration. A decrease of effectiveness was not observed during the one-year therapy. No uniform influence on the laboratory parameters could be revealed. The most frequent side-effects were: gastric discomfort (13 patients), bradycardia (7 patients) and AV-prolongation (3 patients). A total of 77 patients (16.9%) had to discontinue therapy. 29 out of these discontinuations were not therapy-related (drop-outs); 12 were based on an insufficient therapeutic success, 13 on hospitalization, 11 on extracardiac, 4 on cardiac adverse reactions and 8 patients (1.8%) died during the study. In a global assessment the trial physicians described the tolerability as good in 92% of the patients, fair in 2.9% and poor in 2.4%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

[Clinical trial of the antibacterial combination sulfamoxole/trimethoprin (CN 3123). Fifth communication: Comparison of two double-blind studies with CN 3123 undertaken for demonstration of its efficacy (author's transl)].

Two double-blind trials which, independently, revealed the same conclusion that there is no significant difference between the therapeutic effect of N1-(4,5-dimethyl-2-oxazolyl)-sulfanilamide (sulfamoxole) and 2,4-diamino-5-(3,4,5-trimethoxy-benzyl)-pyrimidine (trimethoprim) (CN 3123, Neven, Supristol) and a reference preparation, were compared with each other in respect of rating the therapeutic result. The authors discuss the greater occurrence of Proteus pathogens at one trial centre, and its bearing on the rating of the therapeutic effect.

Bacterial Infections↗