Search PubMed⌕ Search

Biomedical subjects

P Strauss

Publications and source records attributed to P Strauss.

At least 19 recordsLinked to original sources
PubMed2005

Lessons learned from investigations on case study level for modelling of nutrient emissions in the Danube basin.

In the framework of the project daNUbs (Nutrient Management in the Danube Basin and its Impact on the Black Sea) the MONERIS emission model is used for the basin wide calculation of nutrient (nitrogen and phosphorus) emissions in the Danube Basin. The MONERIS model was developed and successfully applied for German river catchments. Based on investigations in selected test regions (case studies) the daNUbs approach is to check the applicability of the MONERIS emission model for the specific conditions of the Danube Basin in more detail than is possible with a basin wide application. Six case studies with areas of 400-3,500 km2 and several subcatchments have been selected in order to represent different conditions along the Danube Basin. In this study region intensive data collection and enhanced monitoring has been performed in order to raise the database significantly above the generally available data. Water balance as well as nutrient balance calculations have been performed with the MONERIS model as well as with other approaches. Results are compared to each other and to data from monitoring. Results up till now showed the applicability and sensitivity of the MONERIS approach in different conditions of the Danube Basin (e.g. emissions via groundwater). They indicated that the nitrogen retention in the catchments is well described with the MONERIS model.

Environmental Monitoring↗
PubMed2005

Considerations on the influence of extreme events on the phosphorus transport from river catchments to the sea.

In this paper, results from rivers of different sizes in Romania, Hungary and Austria are presented. The paper shows the dynamics of extreme events and their contribution to the total P and suspended solids transported in these rivers. Special attention is paid to the influence of the size of the catchment and the event probability on the relative contribution of a single event to the total loads transported in the river. Further, the development of phosphorus loads along the Danube River at a flood event is shown. From the results it can be concluded that there is no immediate influence of high flow and flood events in upstream parts of the Basin on the transport of phosphorus from the catchment to the receiving Sea. Particle-bound phosphorus is mobilised from the catchment (through erosion) and the river bottom to a high extent at high flow events and transported at peak discharges to downstream, where retention by sedimentation of particles takes place. On the one hand this retention is a transport to flooded areas. In this case it can be considered as more or less long term retention. On the other hand sedimentation takes place in the riverbed, in case the tractive effort of the river is reduced. In this second case the P-pool in the sediments of the sedimentation area will be increased. If anaerobic conditions in the sediment appear, part of the phosphorus will be transformed to soluble ortho-phosphate and will continuously contribute to the phosphorus transport to the receiving sea. Part of the P-retained in the river sediment will be mobilised by resuspension at the next biggest high flow event. Altogether, these alternating processes of suspension, transport, export to flooded areas or sedimentation in the river bed with partly solution and partly resuspension at the next event decrease the share of the phosphorus transport during high flow events on the total loads transported in the more downstream parts of a catchments as compared to the more upstream parts. In the year of occurrence of an extreme flood event the P-transport of this year is dominated by the flood event. As an average over many years the contribution of high flow events to the total P-transport still may be between 7 and 20% in smaller catchments (around 1,000 km2). In a big catchment (e.g. river Danube) much smaller contributions of flood events on the total P-transport can be expected as an average over many years.

Austria↗
PubMed2000

Thioredoxin facilitates the induction of heme oxygenase-1 in response to inflammatory mediators.

Heme oxygenase (HO)-1 is a stress response protein that is regulated by oxidative stress. HO-1 catalyzes the generation of biliverdin, carbon monoxide, and iron from heme. Lipopolysaccharide (LPS) and interleukin (IL)-1beta induce HO-1 through the binding of nuclear proteins to AP-1 motifs in enhancer regions upstream from the transcription start site. The DNA binding activity of AP-1 proteins depends on the reduction of cysteines in their DNA-binding domains. We found that agents that disrupt free sulfhydryl groups abolish AP-1 binding activity in nuclear proteins obtained from rat aortic smooth muscle cells and macrophages stimulated with IL-1beta or LPS. Thioredoxin (TRX) may regulate the redox status of nuclear transcription factors in response to oxidative stimuli, thus we determined the role of TRX in the physiologic regulation of HO-1. TRX underwent nuclear translocation in cells stimulated with IL-1beta and LPS. We transfected macrophages with a heterologous promoter construct containing two AP-1 sites from an upstream enhancer region in the HO-1 promoter. Recombinant TRX induced promoter activity to a level analogous to that induced by LPS, and this TRX response was abolished by mutation of the AP-1 sites. An inhibitor of TRX reductase, used to prevent TRX translocation in the reduced state, decreased HO-1 induction by IL-1beta and LPS. These data provide the first evidence that TRX contributes to the induction of HO-1 by inflammatory mediators.

Animals↗
PubMed1997

Stress among package truck drivers.

In 1992, a cross-sectional questionnaire study of package truck drivers in one company was conducted at four widely scattered sites throughout the US; 317 drivers participated, representing 82% of those eligible. The package truck drivers scored significantly above the US working population comparison norm on all summary and individual scales derived from the SCL 90-R, indicating a substantial increase in psychologic distress for this group. The Global Severity Index, the best single summary measure of psychological distress in the SCL 90-R, revealed a mean T score for the drivers of 64.20, 91st percentile of the normative population. The group perceived significantly more daily stressful events than the average working adult, and their sensitivity to these events was also increased. Role overload, a component of the Occupational Stress Inventory, was the most consistent factor associated with symptoms of psychological distress on multiple regression analysis. This study suggests that job stress is a psychological health hazard for these drivers.

Adult↗
PubMed1997

Possible monocytic origin of chondrosarcoma: in vitro transdifferentiation of HLA-DR blood monocyte-like cells from a patient with chondrosarcoma, into neo-fibroblasts and chondrocyte-like cells.

Nodules and multilayered areas composed of fibroblasts and chondrocyte-like cells embedded in an abundant extracellular matrix appeared spontaneously in in vitro culture of mononucleated blood cells taken from a patient with chondrosarcoma. Using specific antibodies it was demonstrated that the neo-fibroblasts which developed in the culture resulted from a direct transdifferentiation of monocytes expressing HLA-DR specificity. The experiment was carried out twice, once before surgery and then two years later. In both cases the spontaneous transdifferentiation of HLA-DR monocytes into neo-fibroblasts was observed. Previously it was shown that normal monocytes were also able to give rise in vitro to neo-fibroblasts. However, the latter are normally rapidly destroyed by cell-cell contact with T-cells. Normal T-cells adhere to normal neo-fibroblasts by which they are finally engulfed. As a result, the neo-fibroblasts lose their fibroblastic shape, no longer adhere to their support and die. Therefore the abnormal proliferation and persistence of neo-fibroblasts in pathological situations such as the present case may result either from an intrinsic defect in monocytes, T-cells or both. The question is whether or not this transdifferentiation process observed in vitro accounts for the development of chondrosarcoma in vivo. The present results suggest that in vivo chondrosarcoma may start in a necrotic zone (resulting for instance from trauma) and attract HLA-DR monocytes, where they accumulate and transdifferentiate into neo-fibroblasts and chondrocyte-like cells. The uncontrolled transdifferentiation of these HLA-DR monocytes resulting from a dysregulation of the immune system is probably linked to the malignant process which may have a retroviral origin. The question is raised regarding the embryologic origin of this special sub-population of blood monocytes in which pluripotential capabilities are retained; its origin may differ from that of the other circulating monocytes.

Cartilage↗
PubMed1995

Extraperitoneal rectal gunshot injuries.

Extraperitoneal rectal gunshot injuries are rare, but may be encountered in civilian practice. We report on a series of 26 such cases. The aim of the study is to attempt to evolve a treatment policy of this injury. The principles of management include the repair of rectal wound in selected cases and the formation of a diverting colostomy. Distal rectal washout and presacral drainage, although advocated by some authors, do not seem to be indispensable adjuncts to the management of these injuries.

Adolescent↗
PubMed1992

A health survey of toll booth workers.

The prevalence of respiratory and other health problems in a cohort of highway toll booth workers was surveyed by mailed questionnaire. In a low proportion of respondents (43.2%), a high prevalence of central nervous system complaints (headaches, irritability, or anxiety, and unusual tiredness), mucous membrane irritation (eye irritation, nasal congestion, and dry throat), and musculoskeletal problems (joint and back pains) was found. We believe these symptoms are reflective of the acute irritant and central nervous system effects of exposure to motor vehicle exhaust. The musculoskeletal complaints are likely the result of bending, reaching, and leaning out of the toll booth. The need for in-depth evaluation of the ventilation systems and the ergonomic and job stressors of work at toll booths is suggested by these results.

Adult↗
PubMed1990

Asbestos bodies in bronchoalveolar lavage fluids of brake lining and asbestos cement workers.

Asbestos body (AB) concentrations in bronchoalveolar lavage samples of 15 brake lining (BL) workers exposed only to chrysotile have been determined and compared with those from 44 asbestos cement (AC) workers extensively exposed to amphiboles. The mean AB concentrations (263 +/- 802 and 842 +/- 2086 AB/ml respectively) for those groups did not differ significantly but were much higher than those found in control groups. Analytical electron microscopy of asbestos body cores showed that in the BL group 95.6% were chrysotile fibres whereas in the AC group amphiboles accounted for 93.1%. The size characteristics of the central fibres differed for chrysotile and amphibole AB, the former being shorter and thinner. Examination of repeated bronchoalveolar lavage samples showed that the mechanisms of clearance of chrysotile fibres do not affect AB concentration for at least 10 months after cessation of exposure. It thus appears that routine counting of ABs in BAL allows the assessment of current or recent occupational exposures to asbestos. Exposures to chrysotile lead to AB concentrations comparable with those encountered in exposures to amphiboles.

Asbestos↗
PubMed1990

[The effect of gamma-aminobutyric acid at the somatic and dendritic level in Purkinje cells in the cerebellum of the frog in vitro].

The effect of gamma-aminobutyric acid (GABA) on its receptors localized on the somatic and dendritic membrane of Purkinje cells was tested on the isolated cerebellum of the frog. The action of GABA was found to be different in the two zones studied. On the membrane of the cell bodies GABA inhibited the overall synaptic potential and spontaneous activity by a mechanism dependent on increased Cl- conductivity resulting in hyperpolarization of the somatic membrane. On the dendritic membrane the inhibitory effect of GABA on the spontaneous activity of dendrites was only minimal and shortlasting. At intradendritic recording a depolarizing effect of GABA was observed whose mechanism is so far unknown.

Action Potentials↗
PubMed1988

Electrophysiological properties of the isolated vestibulocerebellar complex of the frog in vitro.

Parameters of the electrical activity of the isolated vestibulocerebellar complex of the frog were studied under in vitro conditions. In the region of the vestibular nucleus (nc. VIII), in the presence of stimulation of the stato-acoustic nerve (n. VIII), responses from efferent vestibular neurones and from unidentified (probably vestibulospinal) neurones were recorded. The latent periods of their excitatory postsynaptic potentials (EPSPs, 1.4-2.2 ms) were indicative of mono- and disynaptic connection. Inhibitory postsynaptic potentials (IPSPs) were also observed. Stimulation of the auricular lobe of the cerebellum evoked monosynaptic IPSPs, an EPSP-IPSP complex or pure EPSPs in nc. VIII, the latter probably by way of collaterals to the cerebellum. The inhibitory character of the effect of efferents from the cerebellum to the neurones of nc. VIII was demonstrated in the focal synaptic potential and in spontaneous and evoked unit activity. If n. VIII was stimulated, both focal and unit extra- and intracellular responses characteristic of activation of the Purkinje cells by mossy (MF) or climbing (CF) afferent fibres were recorded in the cerebellar cortex. The electrophysiological picture indicates that both synaptic transmission and the functional manifestations of the individual neurones are preserved in the tested preparation.

Animals↗
PubMed1987

Cost-benefit analysis of hepatitis-B vaccination.

Since 1983 the Belgian insurance Fund for Occupational Disease (FOD) has refunded the cost of hepatitis-B (HB) vaccination. Vaccination has been carried out by occupational physicians selectively on staff in hospitals and medical-care institutions. At the end of 1986, 40,000 people at high risk of HBV infection had been vaccinated. The vaccination costs are largely offset by the benefits resulting from the striking fall in the number of HB cases. The financial investment has proved economically beneficial for the insurance fund.

Belgium↗
PubMed1986

Comparison of the effect of gamma-aminobutyric acid and its derivative baclofen on the activity of Purkinje cells of frog cerebellum in vitro.

The inhibitory effect of gamma-aminobutyric acid (GABA) and its synthetic derivative baclofen were compared in frog cerebellum in vitro. Baclofen inhibited synaptic transmission from parallel fibres to the Purkinje cells in EC50 concentrations approximately 200-fold lower than for GABA. In addition to its inhibitory effect, GABA induced temporary facilitation of responses in the dendrite zone by a mechanism dependent on the presence of a normal Cl- concentration; the inhibitory phase was only partly sensitive to reduction of the Cl- concentration in the medium and to the administration of picrotoxin. The action of baclofen, which was unaffected by these treatments, requires an intact catecholamine and serotonin pool, since it is ineffective in reserpine-treated animals. Both substances also influence the excitability of parallel fibres. In solutions with a high Mg2+ and a low Ca2+ concentrations GABA inhibits the spontaneous activity of Purkinje cells by acting on the postsynaptic membrane of the soma and the primary dendrites. The effect of baclofen is evidently the outcome of inhibition of transmitter release from presynaptic endings.

Action Potentials↗
PubMed1984

[Does human fibrin glue improve results in tympanoplasty?].

Human fibrin tissue adhesive diminishes the rate of recurrent perforations in tympanoplastic on a statistical base (n = 1051). The postoperative air-bone gap (1000 cps) was not influenced in a substantial amount by using tissue adhesive. The reconstruction of the lateral attic wall by endogenous conchal cartilage was facilitated by the application of fibrin tissue adhesive. In animal experiments with guinea pigs ("attic" of bulla tympanica) human fibrin tissue adhesive is superior to free muscle transplants in reconstruction of the bony bulla wall. Fibrin adhesive induces scar formation, therefore a very sparing use is necessary.

Animals↗
PubMed1982

Electrophysiological characteristics of reticulospinal neurones in relation to the conduction velocity of their axons.

Activity was recorded intracellularly from the bodies of 87 reticulospinal neurones in the cat's gigantocellular nucleus, whose axons had a conduction velocity of 18-148 m.s-1. Slow-conducting neurones (18-45 m.s-1, 23%) were characterized by a wider action potential, higher input resistance (3.8-7.0 M omega) and a lower rheobase (1.0-1.7 nA). They were also very sensitive to changes in membrane polarity and generated regular rhythmic activity. Fast-conducting neurons (45-148 m.s-1) were characterized by a short action potential, low input resistance (0.7-2.9 M omega) and a higher rheobase (1.5-5.2 nA). When depolarizing current pulses were applied, they generated responses with action potentials with a high frequency, especially in the initial phase of depolarization, but their thresholds for the initiation of activity and steady firing were higher than in the case of slow neurones. Slow reticulospinal neurones always responded to stimulation of the spinal funiculi (mainly the dorsal funiculus) by a characteristic large postsynaptic potential on which large numbers of spike potentials were superimposed and which did not occur in fast neurones. The differences observed in membrane properties and in the character of generation of action potentials draw attention to the phasic character of fast, and the tonic character of slow, reticulospinal neurones.

Action Potentials↗