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Biomedical subjects

J Wehner

Publications and source records attributed to J Wehner.

14 recordsLinked to original sources
PubMed2001

Protection of bacterial spores in space, a contribution to the discussion on Panspermia.

Spores of Bacillus subtilis were exposed to space in the BIOPAN facility of the European Space Agency onboard of the Russian Earth-orbiting FOTON satellite. The spores were exposed either in dry layers without any protecting agent, or mixed with clay, red sandstone, Martian analogue soil or meteorite powder, in dry layers as well as in so-called 'artificial meteorites', i.e. cubes filled with clay and spores in naturally occurring concentrations. After about 2 weeks in space, their survival was tested from the number of colony formers. Unprotected spores in layers open to space or behind a quartz window were completely or nearly completely inactivated (survival rates in most cases < or = 10(-6)). The same low survival was obtained behind a thin layer of clay acting as an optical filter. The survival rate was increased by 5 orders of magnitude and more, if the spores in the dry layer were directly mixed with powder of clay, rock or meteorites, and up to 100% survival was reached in soil mixtures with spores comparable to the natural soil to spore ratio. These data confirm the deleterious effects of extraterrestrial solar UV radiation. Thin layers of clay, rock or meteorite are only successful in UV-shielding, if they are in direct contact with the spores. The data suggest that in a scenario of interplanetary transfer of life, small rock ejecta of a few cm in diameter could be sufficiently large to protect bacterial spores against the intense insolation; however, micron-sized grains, as originally requested by Panspermia, may not provide sufficient protection for spores to survive. The data are also pertinent to search for life on Mars and planetary protection considerations for future missions to Mars.

Bacillus subtilis↗
PubMed2001

Staphylococcus aureus enterotoxins induce histamine and leukotriene release in patients with atopic eczema.

BACKGROUND: Chronic skin colonization with Staphylococcus aureus is a characteristic feature of atopic eczema (AE), and about 60% of S. aureus strains isolated from the skin of patients with AE secrete enterotoxins. Furthermore, IgE antibodies to S. aureus enterotoxins have been identified in 78% of patients with AE. OBJECTIVES: To examine the S. aureus enterotoxin-induced histamine and leukotriene release of basophils from patients with AE. METHODS: Peripheral blood basophils from patients with AE were stimulated with the staphylococcal enterotoxins A, B, D, E and toxic shock syndrome toxin-1. Additionally, priming experiments were performed with interleukin (IL)-3, IL-8 and granulocyte/macrophage colony-stimulating factor followed by stimulation with S. aureus enterotoxins. RESULTS: In patients with AE, basophils secreted significantly higher amounts of histamine and leukotriene C4 (LTC4) than in healthy controls. The priming experiments showed additional histamine and LTC4 release in the group of AE patients. CONCLUSIONS: Histamine and leukotriene generation from atopic basophils stimulated with staphylococcal enterotoxins may indicate a role for these toxins as possible allergens in at least a subgroup of patients with AE.

Bacterial Toxins↗
PubMed1995

Biological responses to space: results of the experiment "Exobiological Unit" of ERA on EURECA I.

Spores of different strains of Bacillus subtilis and the Escherichia coli plasmid pUC19 were exposed to selected conditions of space (space vacuum and/or defined wavebands and intensities of solar ultraviolet radiation) in the experiment ER 161 "Exobiological Unit" of the Exobiology Radiation Assembly (ERA) on board of the European Retrievable Carrier (EURECA). After the approximately 11 months lasting mission, their responses were studied in terms of survival, mutagenesis in the his (B. subtilis) or lac locus (pUC19), induction of DNA strand breaks, efficiency of DNA repair systems, and the role of external protective agents. The data were compared with those of a simultaneously running ground control experiment. The survival of spores treated with the vacuum of space, however shielded against solar radiation, is substantially increased, if they are exposed in multilayers and/or in the presence of glucose as protective, whereas all spores in "artificial meteorites", i.e. embedded in clays or simulated Martian soil, are killed. Vacuum treatment leads to an increase of mutation frequency in spores, but not in plasmid DNA. Extraterrestrial solar ultraviolet radiation is mutagenic, induces strand breaks in the DNA and reduces survival substantially; however, even at the highest fluences, i.e. 3 x 10(8) J m-2, a small but significant fraction of spores survives the insolation. Action spectroscopy confirms results of previous space experiments of a synergistic action of space vacuum and solar UV radiation with DNA being the critical target.

Bacillus subtilis↗
PubMed1995

Effects of vacuum UV and UVC radiation on dry E. coli plasmid pUC19. I. Inactivation, lacZ- mutation induction and strand breaks.

Using Escherichia coli plasmid pUC19 as a test system to study the effects of radiation on DNA at the molecular level, the wavelength (160-254 nm) dependence of inactivation (loss of the ability to transform E. coli), mutation induction in the target gene lacZ and induction of single-strand breaks and double-strand breaks was investigated. The same fluences were applied for all endpoints tested. In the UVC range, the cross-sections of inactivation and mutation induction match the DNA absorption curve, whereas the cross-section for single-strand break induction deviates from the DNA curve, especially at 220 nm. In the vacuum UV range, with increasing energy of the photons, the cross-sections of inactivation and single-strand breaks increase sharply (from 190 to 160 nm by more than one order of magnitude), which is not reflected by the DNA curve. In this UV range, the shape of the action spectrum is similar to that of the absorption curve of the sugar phosphate moiety of DNA. Only after irradiation with vacuum UV at 160 nm are double-strand breaks detected. Their induction rate is about one order of magnitude lower than that of single-strand breaks at the same wavelength; however, their induction rate is at least twice that of single-strand breaks at longer wavelengths. Concerning mutation induction, the increment in the vacuum UV range is less well expressed. The data suggest the contribution of different kinds of photochemical injury to inactivation and mutation induction.

Dose-Response Relationship, Radiation↗
PubMed1995

Effects of vacuum UV and UVC radiation on dry Escherichia coli plasmid pUC19. II. Mutational specificity at the lacZ gene.

The mutational spectra at the lacZ gene, induced either by vacuum UV at 160 nm or UVC at 254 nm in vacuum-dried preparations of Escherichia coli plasmid pUC19 DNA, have been characterized from 72 E. coli-propagated mutants by DNA sequencing. In plasmids irradiated in vacuum, vacuum UV is five times more mutagenic than UVC. In the UV-induced mutants, base substitutions largely predominate, with GC-->AT (G, guanine; C, cytosine; A, adenine; T, thymine) transitions being the most abundant type of base change for vacuum UV (61%) and UVC (47%). Most of the GC-->AT transitions appear to occur at dipyrimidine sites, which are located at the non-transcribed DNA strand. Some, but not all, hot spots for GC-->AT transitions are identical for vacuum UV and UVC. Frameshifts, resulting from a loss of the thymine residue, are specific for UVC (22%), and were not detected after treatment with vacuum UV. They occur predominantly at thymine runs of the transcribed DNA strand. Only a few deletions were detected following irradiation with vacuum UV (7.5%) and UVC (2%); however, their frequency is not enhanced compared with the spontaneous mutation spectrum. The data confirm the important role of base substitution mutations in UV-induced mutagenesis, which is not only valid for the UVC range, but extends towards the vacuum UV range.

Base Sequence↗
PubMed1994

DBA/2 and C57BL/6 mice differ in contextual fear but not auditory fear conditioning.

It has been proposed that DBA/2 and C57BL/6 mice perform differently on some learning and memory tasks because of functional differences in the hippocampal formation. To evaluate this hypothesis, DBA/2 and C57BL/6 mice were tested on 2 forms of conditioned fear: contextual fear conditioning, which depends on the integrity of the hippocampal formation, and auditory cue conditioning, which does not. Both mouse strains displayed equivalent conditioning when the auditory cue was paired with shock, but DBA/2 mice showed significantly less conditioning to the context in which shock was experienced. These results are consistent with the hypothesis that the pattern of spared and impaired performance, which DBA/2 mice display on a variety of learning and memory tasks, is related to impaired hippocampal formation function.

Animals↗
PubMed1990

Value of inhaled antibiotics in cystic fibrosis patients.

The authors give a survey of problems concerning the use of antibiotic aerosols in cystic fibrosis patients. They give recommendations when and how to use this form of treatment. The combination of inhaled antibiotics with the oral or intravenous antibiotic therapy can be recommended best for patients with a chronic lung infection with Pseudomonas aeruginosa.

Administration, Inhalation↗
PubMed1990

Lateral ankle dislocation without fracture.

Ankle fracture dislocations are a common entity in orthopaedic practice and their treatment is well documented. Dislocations of other joints are usually treated by closed reduction with a brief period of immobilization. This ankle dislocation without fracture is a rare injury which was treated similarly to other joint dislocations. An intact bony construct of an ankle following dislocation allows for subsequent joint stability when soft tissues have healed.

Adult↗
PubMed1988

Nigral 5-HT and substance P-induced enhancement of passive avoidance retention.

Peripheral, posttraining injection of substance P (SP) has been shown to facilitate the retention of aversive and appetitive learning tasks, suggesting that SP may play a role in information processing. In addition, SP may modulate the release of nigrostriatal monoamines, which have also been linked with avoidance learning. This paper examines the interaction between SP and nigrostriatal monoamines by observing the behavioral effects of neurochemical lesions on SP-induced avoidance retention, and by measuring changes in nigrostriatal monoamine activity and receptor regulation following avoidance training and SP injection. In Expt. 1, 5,7-dihydroxytryptamine lesions of the substantia nigra, but not the caudate, attenuated the retention-enhancing effects of posttraining SP injection. Further, 6-hydroxydopamine lesions of the substantia nigra produced a deficit in avoidance conditioning that was reversed by posttraining SP injection. Expts. 2 and 3 demonstrated that although passive avoidance training and posttraining SP injections did not significantly alter nigral 5-hydroxytryptamine (5-HT) activity, SP increased 5-HT1 receptor density. It was concluded that SP may affect avoidance retention by modulating nigral 5-HT activity.

Animals↗
PubMed1988

Brachioradialis to finger extensor tendon transfer to achieve hand opening in acquired spasticity.

Four patients with adult acquired spastic hemiplegic hand disorders had brachioradialis to extensor digitorum communis tendon transfer to establish motor balance and improve prehensile hand function. All of the patients had volitional control of the wrist and finger flexors without control of the finger extensors, producing a dynamic hand deformity in which the patients could initiate grasp without release. Dynamic electromyography in these patients revealed electrical activity of the brachioradialis muscle during active elbow extension, making a seemingly "out-of-phase" muscle available for "in-phase" tendon transfer. At follow-up, ranging from 26 to 36 months (average of 30.2 months), all four patients improved three functional levels. Translated to functional capacity all of the patients had no functional capacity before operation and good assistive prehension afterward.

Adult↗
PubMed1988

[Acute foreign body aspiration as a respiratory emergency in childhood].

From 1957 to 1987 altogether 206 cases of tracheobronchial foreign body aspiration were diagnosed. Two third of the patients were one or two years old. Boys prevailed with 57 per cent. 55 per cent of all foreign bodies were nuts. Only 10 per cent were radiopaque (screws, nails, needles or pieces of bones). The attempt to eliminate the foreign body via the bronchoscope was successful in 96 per cent and failed in seven cases. Six children had to undergo a thoracotomy. In one third of the cases the foreign body remained two weeks or longer in the bronchial tree. 66 children with such a "chronic" foreign body were later on examined by bronchography, which showed in 29 per cent severe deformations of the bronchial wall and in 14 per cent even bronchiectasis. An acute foreign body aspiration should always be considered and handled as an emergency.

Bronchi↗
PubMedDate not supplied

Crankshaft phenomenon in congenital scoliosis: a preliminary report.

To determine whether or not the crankshaft phenomenon occurs after spinal fusion in patients with congenital scoliosis, we reviewed 23 curves in 21 patients who were operated on before age 10 years. Operative procedures consisted of various kinds of posterior fusions as well as anterior and posterior hemiepiphyseodeses. Seven of the 23 curves progressed greater than or equal to 10 degrees during the course of follow-up, and six of the seven demonstrated increased rotation and were believed to demonstrate the crankshaft phenomenon. No spines rotated without curve progression. The only statistically predictive factor was length of follow-up. No curve that underwent anterior and posterior hemiepiphyseodeses demonstrated the crankshaft phenomenon. Although the crankshaft phenomenon can occur in young patients operatively treated for congenital scoliosis, apparently it can be prevented by anterior fusion.

Bone Diseases, Developmental↗
PubMedDate not supplied

[Phenobarbital poisoning in a eutrophic term newborn infant. A case report].

An iatrogenic intoxication with 300 mg phenobarbital (Lepinal) in a newborn is reported. Description is given about clinical course, blood levels of phenobarbital (maximum 507 mumols/l) and the therapy. The most important therapeutic interventions like alkalinization of urine, haemoperfusion or blood exchange are directed towards increase of elimination of phenobarbital. The phenobarbital blood level decreased from 349 mumols/l before to 242 mumols/l after the blood exchange transfusion in our case. The transfer to a pediatric intensive care unit should be made as early as possible because of the risk of respiratory failure.

Combined Modality Therapy↗