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Biomedical subjects

S Ludwig

Publications and source records attributed to S Ludwig.

At least 19 recordsLinked to original sources
PubMed2007

Sirolimus improves early microcirculation, but impairs regeneration after pancreatic ischemia-reperfusion injury.

Ischemia and reperfusion injury remains a relevant problem in clinical pancreas transplantation. We investigated the effect of sirolimus (SRL) in a rodent model of 90-min warm pancreatic ischemia. Four groups were studied: (1) sham surgery and vehicle; (2) sham surgery and SRL; (3) warm ischemia and vehicle; (4) warm ischemia and SRL. SRL (1.5 mg/kg/day) and vehicle were administered intraperitoneally for 3 days prior to surgery until the animals were killed. Microcirculation was assessed immediately after reperfusion by means of intravital fluorescence microscopy. Histopathological injury, apoptosis, proliferation and biochemical parameters were analyzed at 2 h, 1 day and 5 days after surgery. Ninety minutes after ischemia, intravital microscopy revealed an improved functional capillary density (p < 0.05) and reduction of adherent leucocytes (p < 0.01) and platelets (p < 0.05) in the SRL-treated group compared to the vehicle-treated controls. In contrast, on day 5 after ischemia, the pancreatic tissue of SRL-treated animals showed a higher grade of histological injury (p < 0.05) and higher rate of apoptotic cells (p < 0.05) than the vehicle controls. In summary, our data indicate that administration of SRL improves microcirculation at a very early stage, but results in an impairment of the recovery phase after pancreatic ischemia-reperfusion injury.

Animals↗
PubMed2006

Double-dot quantum ratchet driven by an independently biased quantum point contact.

We study a double quantum dot (DQD) coupled to a strongly biased quantum point contact (QPC), each embedded in independent electric circuits. For weak interdot tunneling we observe a finite current flowing through the Coulomb blockaded DQD in response to a strong bias on the QPC. The direction of the current through the DQD is determined by the relative detuning of the energy levels of the two quantum dots. The results are interpreted in terms of a quantum ratchet phenomenon in a DQD energized by a nearby QPC.

Aluminum↗
PubMed2006

Esophageal injury from thoracic pedicle screw placement in a polytrauma patient: a case report and literature review.

The authors present a case report illustrating a visceral complication that may occur as result of thoracic pedicle screw placement. The case describes the previously unreported occurrence of esophageal impingement secondary to anterior vertebral body perforation by a pedicle screw at the third thoracic vertebra. This case highlights the challenge of thoracic pedicle screw placement and the importance of preoperatively measuring the maximum anterior-posterior dimension of the vertebral body.

Adolescent↗
PubMed2005

[Accumulated occurrence of illnesses with Salmonella enteritidis in hospitals and nursing homes in the district Oberallgaeu, Bavaria, in July 2004].

We report on the investigation of a Salmonella enteritidis outbreak in hospitals and nursing homes in the district Oberallgaeu, Bavaria, in July 2004. Affected by this outbreak were hospital patients, inhabitants of nursing homes, kitchen coworkers and maintenance personnel. Within this outbreak six deaths were observed. A forensic medical investigation of four deaths revealed two cases of Salmonella enteritis as the primary cause of death, another cause of death was due to other causes and one cause of death remained unclear. The microbiological investigation of stool samples linked all positive samples to an outbreak during this period. The epidemiological outbreak curve pointed towards a foodborne transmission of the pathogen. The infection period could be limited to the weekend of the 3./4.7.2004. All affected institutions were supplied by a catering service with several sites. All tested food samples were negative for Salmonella enteritis. Epidemiological investigations revealed that a contaminated pudding was probably responsible for the outbreak.

Adult↗
PubMed2004

Burden of illness imposed by severe sepsis in Switzerland.

OBJECTIVE: This study aims to determine the burden of illness imposed by severe sepsis in Switzerland by evaluating the direct and indirect patient-related costs for critically ill patients with severe sepsis. METHODS: In order to estimate the direct costs a retrospective analysis was undertaken using records from 61 adult patients treated in three intensive care units (ICUs) in three different University hospitals in Switzerland, in 2001. Resource use was determined by a bottom up approach and valued using centre-specific unit costs for medication, nutrition, blood products, disposables and official tariffs for laboratory and microbiology analysis, diagnostic services, and clinical procedures. By adding centre-specific personnel and basic bed (hotel) costs total direct costs in the ICU were calculated. Indirect costs resulting from unfitness for work, early retirement, and premature death were calculated using official Swiss statistics for the years 1998-2000. RESULTS: The mean total direct costs for a severely septic patient are CHF 41,790 (+/- 33,222 CHF) or CHF 3244 (+/- 757 CHF) per day. Nonsurvivors cause significantly higher costs than survivors (CHF 45,956 vs. CHF 37,759, p <0.001). The total intensive care costs in Switzerland due to severe sepsis amount to CHF 146-355 million. Indirect costs were estimated to range from CHF 347 to 844 million (predominantly due to premature death). Consequently the burden of illness of severe sepsis can be estimated to range from CHF 493 to 1199 million per year in Switzerland (1 CHF = 0.662 Euro in 2001). CONCLUSION: Patients suffering from severe sepsis in Switzerland have a high mortality rate and spend a prolonged time in the ICU, leading to high direct and indirect costs. Particularly productivity losses due to premature death represent a considerable burden to the Swiss society.

Adolescent↗
PubMed2004

Ozone exposures during trans-continental and trans-Pacific flights.

UNLABELLED: Ozone concentrations were passively monitored in passenger cabins of commercial airliners flying domestic, Pacific, and south-east Asian routes. One-hundred and six flight segments were monitored for either the full duration and/or approximately 3 h during the middle portion of the flight for a total of 145 time-integrated measurements. Over all samples the mean (+/-SD) concentration was 80 p.p.b. (30.1). Twenty percent of the measurements exceeded 100 p.p.b., the FAA-recommended level. Eleven percent of the measurements exceeded 120 p.p.b., the US EPA's short-term National Ambient Air Quality Standard for ozone. Ozone concentrations measured on Pacific flights were substantially higher during mid-flight than over the full flight (95 p.p.b. vs. 56 p.p.b). Ozone concentrations on the northern Pacific routes were higher than concentrations for other Pacific flights. Season comparison showed that ozone levels were higher during the winter and spring than for the summer and fall. Our study shows that even in aircraft with catalytic ozone converters, passengers and flight crew may be exposed to elevated ozone levels on domestic and international flights. Given the frequency of ozone excess, it is recommended that (1) ozone converters should be required equipment on all commercial passenger aircraft for mid and high latitude routes (2) improved maintenance procedures should be required for catalytic converters (e.g., more frequent servicing/replacement), and (3) ozone should be routinely monitored on all mid and high latitude flights. PRACTICAL IMPLICATIONS: The authors have demonstrated elevated ozone concentrations in passenger cabins. They give several practical recommendations to help solve the problem.

Air Pollution, Indoor↗
PubMed2004

Differences in cell activation by Chlamydophila pneumoniae and Chlamydia trachomatis infection in human endothelial cells.

Seroepidemiological studies and demonstration of viable bacteria in atherosclerotic plaques have linked Chlamydophila pneumoniae infection to the development of chronic vascular lesions and coronary heart disease. In this study, we characterized C. pneumoniae-mediated effects on human endothelial cells and demonstrated enhanced phosphorylation and activation of the endothelial mitogen-activated protein kinase (MAPK) family members extracellular receptor kinase (ERK1/2), p38-MAPK, and c-Jun-NH2 kinase (JNK). Subsequent interleukin-8 (IL-8) expression was dependent on p38-MAPK and ERK1/2 activation as demonstrated by preincubation of endothelial cells with specific inhibitors for the p38-MAPK (SB202190) or ERK (U0126) pathway. Inhibition of either MAPK had almost no effect on intercellular cell adhesion molecule 1 (ICAM-1) expression. While Chlamydia trachomatis was also able to infect endothelial cells, it did not induce the expression of endothelial IL-8 or ICAM-1. These effects were specific for a direct stimulation with viable C. pneumoniae and independent of paracrine release of endothelial cell-derived mediators like platelet-activating factor, NO, prostaglandins, or leukotrienes. Thus, C. pneumoniae triggers an early signal transduction cascade in target cells that could lead to endothelial cell activation, inflammation, and thrombosis, which in turn may result in or promote atherosclerosis.

Chlamydia trachomatis↗
PubMed2003

Field-induced structural aging in glasses at ultralow temperatures.

In nonequilibrium experiments on the glasses Mylar and BK7, we measured the excess dielectric response after the temporary application of a strong electric bias field at millikelvin temperatures. A model recently developed describes the observed long time decays qualitatively for Mylar [Phys. Rev. Lett. 90, 105501(2003)]], but fails for BK7. In contrast, our results on both samples can be described by including an additional mechanism to the mentioned model with temperature independent decay times of the excess dielectric response. As the origin of this novel process beyond the "tunneling model" we suggest bias field induced structural rearrangements of "tunneling states" that decay by quantum mechanical tunneling.

Journal Article↗
PubMed2003

Dynamics of the destruction and rebuilding of a dipole gap in glasses.

After a strong electric bias field is applied to the polyester glass Mylar at temperatures in the mK range, its dielectric constant increases and then decays logarithmically in time. We observed its dielectric response for several temperatures and different field sweeps. Starting from the dipole gap theory, we developed a model suggesting that the change in dielectric constant after transient application of a bias field is only partly due to relaxational processes. In particular, nonadiabatic driving of tunneling states (TSs) by applied electric fields causes additional dielectric response. Also, we find that for T less, similar 50 mK the relaxation of TSs is caused primarily by mutual interactions.

Journal Article↗
PubMed2003

Sagittal craniosynostosis: cognitive development, behaviour, and quality of life in unoperated children.

30 patients (23 m/7 f) with untreated, isolated sagittal craniosynostosis (ISC) were re-evaluated at an average age of 9.25 years (2.5 - 25.5). Assessed were neurological status, head shape, school performance, behaviour (with Child Behavior Checklist CBCL), quality of life (TACQOL questionnaire), and a detailed neuropsychological testing (30 patients, 17 siblings as controls). Almost all patients/parents were pleased with the current situation. The aesthetic appearance seemed less obvious compared to photos in infancy. Psychological adjustment as measured by the CBCL was well within normal range. There was a slight tendency for increased internalizing symptoms. TACQOL revealed a lower score for positive emotions. Total score and subscores of test batteries assessing general intellectual performance were in the average range. 6 patients had below average scores in subtests for learning and memory. 12 children had below average scores in one or more subtests for attention. These "deficits" were obviously not of functional importance as all children attended regular school classes (1 exception, an immigrant child of low socio-economic status). These reassuring results regarding school performances, behaviour, and quality of life as well as aesthetic outcome may be helpful when discussing the indication for surgical correction of ISC.

Adolescent↗
PubMed2002

Evidence for magnetic field induced changes of the phase of tunneling states: spontaneous echoes in (KBr)(1-x)(KCN)(x) in magnetic fields.

Recently it was discovered that, in contrast to expectations, the low-temperature dielectric properties of some multicomponent glasses depend strongly on magnetic fields. The low-temperature dielectric response of these materials is governed by atomic tunneling systems. We now have investigated the influence of magnetic fields on the coherent properties of atomic tunneling states in a crystalline host in two-pulse echo experiments. As in glasses, we observe a very strong magnetic field dependence of the echo amplitude. Moreover, for the first time we have direct evidence that the magnetic fields change the phase of coherent tunneling systems.

Journal Article↗
PubMed2002

Direct coupling of magnetic fields to tunneling systems in glasses.

We report on investigations of spontaneous polarization echoes in the nonmagnetic multicomponent glass BaO-Al2O3-SiO2 in static magnetic fields. While the echo decay is only marginally influenced, the echo amplitude depends strongly on magnetic fields. It seems that the intrinsic magnetic moment of tunneling systems causes dephasing effects which are detected in our echo experiments. In addition we find a strong increase of the echo amplitude with magnetic fields. This result shows that the coupling of the tunneling systems to magnetic fields is surprisingly strong and cannot be understood on the basis of current theories.

Journal Article↗