Biomedical subjects

M Steffen

Publications and source records attributed to M Steffen.

At least 19 recordsLinked to original sources

PubMed2002

Isolation of Carnobacterium piscicola from human pus--case report.

Carnobacterium piscicola was first described in 1984. These bacteria are often isolated from fish afflicted with bacterial infections. To date, there has been no reported isolation of this bacterium from human specimens. We report here the isolation of C. piscicola from the pus following traumatic amputation of the right hand in the wrist of a 35-year-old man. The traumatic amputation occurred with an industrial water sawmill. The identity of the human strain was determined biochemically, by 16S rDNA sequence similarity and by fatty-acid methyl-ester profile from bacterial cell.

Adult↗

PubMed2002

[Critical infusion incident caused by incorrect use of a patient-controlled analgesia pump].

We report on the case of a 17-year-old male patient who received a PCA pump after nephrectomy for postoperative analgesia. The syringe of the PCA pump was filled with 50 mg morphine and positioned about 25 cm above the heart. Since the piston of the syringe was not bolted while the pump was switched off, an unnoticed accidental evacuation of the whole content of the syringe into the intravenous line of the patient occurred because of gravity. This problem exists not only with PCA pumps, but can happen with syringe pumps in general. The incident, which can only be explained by strongly reduced venous pressure, was detected by chance. No harm resulted for the patient, but under different conditions it could have been lethal. This critical incident was caused by various factors: incorrect application in combination with insufficient experience or training, stress, inadequate handing-over of the patient and a lack of arrangements and instructions for procedures in routine situations. Suggestions for preventing such dangerous critical incidents are made and discussed. In particular, an algorithm for the correct procedure when inserting or changing the syringe of a syringe pump is presented.

Adolescent↗

PubMed2001

Metabolism of S-nitrosoglutathione in intact mitochondria.

S-nitrosation of protein thiol groups by nitric oxide (NO*) is a widely recognized protein modification. Only few intracellular S-nitrosated proteins have been identified and it has been reported that S-nitrosation/denitrosation can serve as a regulatory process in signal-transduction pathways. Given the potential physiological importance of S-nitrosothiols, and considering that mitochondria are endowed with high levels of thiols and the biochemical requisites for synthesizing NO*, we examined the occurrence of S-nitrosoglutathione (GSNO) in intact, coupled rat liver mitochondria. These organelles contained 0.34 nmol of GSNO/mg of protein, detected by HPLC with UV-visible and electrochemical detections. This concentration was dynamically modulated by the availability of NO*; its decay was affected mainly by GSH and superoxide dismutase in a reaction that entailed the generation of GSSG. On the basis of the relatively long half-life of GSNO and the negligible recovery of NO* during its decay, roles for GSNO as a storage and transport molecule for NO* are discussed. Moreover, the formation of GSNO and its reaction with GSH can be considered to be partly responsible for the catabolism of NO* via a complex mechanism that might result in the formation of hydroxylamine, nitrite or nitrous oxide depending upon the availability of oxygen, superoxide dismutase and glutathione. Finally, the high concentrations of GSH in the cytosol and mitochondria might favour the formation of GSNO by reacting with NO* 'in excess', thereby avoiding damaging side reactions (such as peroxynitrite formation), and facilitate the inactivation of NO* by generating other nitrogen-related species without the chemical properties characteristic of NO*.

Animals↗

PubMed2001

Limits of photosynthesis in extrasolar planetary systems for earth-like planets.

We present a general modeling scheme for investigating the possibility of photosynthesis-based life on extrasolar planets. The scheme focuses on the identification of the habitable zone in main-sequence-star planetary systems with planets of Earth mass and size. Our definition of habitability is based on the long-term possibility of photosynthetic biomass production as a function of mean planetary surface temperature and atmospheric CO2-content. All the astrophysical, climatological, biogeochemical, and geodynamic key processes involved in the generation of photosynthesis-driven life conditions are taken into account. Implicitly, a co-genetic origin of the central star and the orbiting planet is assumed. The numerical solution of an advanced geodynamic model yields realistic look-up diagrams for determining the limits of photosynthesis in extrasolar planetary systems, assuming minimum CO2 levels set by the demand of C4 photosynthesis.

Atmosphere↗

PubMed2001

Childhood outcome after early high-frequency oscillatory ventilation for neonatal respiratory distress syndrome.

OBJECTIVE: In a previous multicenter controlled clinical trial, we randomly assigned surfactant-treated premature newborns with moderate to severe respiratory distress syndrome to early treatment with high-frequency oscillatory ventilation (HFOV) or to conventional ventilation (CV). Compared with control infants who were treated with CV, neonates who were treated with HFOV using a strategy designed to recruit and maintain lung volume and minimize oxygen exposure had clinical evidence of improved pulmonary outcome and less lung injury. We report a follow-up study designed to determine whether clinical differences persisted between these study groups. METHODS: Patients were recruited from 81 survivors at 1 center (Provo, Utah) and evaluated for sociodemographic and health history, growth, mental development, motor proficiency, and pulmonary function. RESULTS: Eighty-seven percent of the cohort who originally were assigned to treatment with HFOV (n = 36) or CV (n = 33) were seen in follow-up at a mean age of 77 months (6.4 years). There were no differences in the frequency of hospitalization, pulmonary illness, asthma, or disabilities. Growth, verbal IQ, and motor development were appropriate for age and not different between groups. Patients who initially were randomized to treatment with CV showed pulmonary function evidence of decreased peak expiratory flow, increased residual lung volume, and maldistribution of ventilation. CONCLUSION: Neurodevelopmental childhood outcome after early intervention HFOV was normal and not different compared with patients who were treated with CV. Surfactant replacement combined with early HFOV using a lung recruitment strategy ameliorates the acute lung injury in respiratory distress syndrome that predisposes some preterm infants to develop chronic lung disease.

Child↗

PubMed2001

Motility factors identified in supernatants of human cholangiocarcinoma cell lines.

Motility factors, e.g. SF/HGF (scatter factor/hepatocyte growth factor) or AMF (autocrine motility factor) can influence the migration of tumor cells in vitro and may facilitate invasive growth and metastases in vivo. The production of motility factors was studied in cell lines derived from human cholangiocarcinomas. Culture supernatants from 5 different cholangiocarcinoma cell lines (EGI-1, RPMI 7451, MZ CHA-1, MZ CHA-2 and MZ CHA-3) were analyzed in scatter assays with NRK and MDCK cells as indicator cells which react with cellular migration in the presence of motility factors. Culture supernatants from 4 of the 5 cell lines investigated induced migration of the indicator cells thus demonstrating the production of motility factors. Three of the cell lines (MZ CHA-1, MZ CHA-2, RPMI 7451) produced a factor with a molecular weight ranging between 50 and 100 kDa, EGI-1 cells secreted a factor with a molecular weight >100 kDa. None of the factors was identical to HGF as demonstrated by the lacking reactivity in a HGF specific ELISA and by the inability to induce scattering of HPAF indicator cells like HGF. Similar to SF/HGF, the activity of the EGI-1 factor was inhibited by the proteoglycan heparin and stimulated the chemotactic cell migration, but in contrast to SF/HGF it could not induce invasive growth of NRK cells. The production of scatter factors could be involved in tumor progression and formation of metastases of cholangiocarcinomas.

Bile Duct Neoplasms↗

PubMed2000

Experimental realization of an order-finding algorithm with an NMR quantum computer.

We report the realization of a nuclear magnetic resonance quantum computer which combines the quantum Fourier transform with exponentiated permutations, demonstrating a quantum algorithm for order finding. This algorithm has the same structure as Shor's algorithm and its speed-up over classical algorithms scales exponentially. The implementation uses a particularly well-suited five quantum bit molecule and was made possible by a new state initialization procedure and several quantum control techniques.

Journal Article↗

PubMed2000

Simultaneous soft pulses applied at nearby frequencies

The rotation of a spin subject to an on-resonance soft pulse and simultaneously to a soft pulse at a nearby frequency may strongly deviate from the desired rotation expected for a single on-resonance pulse. The deviation is the result of transient frequency shifts of the spin caused by the off-resonance irradiation. We show that the resulting error can be corrected by shifting the frequency of the on-resonance pulse in such a way that it tracks the shift of the spin frequency. Experimentally, the effectiveness of this simple and intuitive method is demonstrated for simultaneous inversions at nearby frequencies in the case of both coupled and uncoupled spins. Simulations predict that the correction technique is effective for arbitrary pulse shapes and tip angles and is particularly useful when the frequency window of the shaped pulse is two to eight times the frequency separation between the chemical shifts of the two spins. Copyright 2000 Academic Press.

Journal Article↗

PubMed2000

Mycophenolate mofetil: lack of efficacy in chronic active inflammatory bowel disease.

BACKGROUND: Mycophenolate mofetil (MMF) is a new immunosuppressant with pharmacodynamic properties comparable to azathioprine. Recent reports found MMF to be effective in inflammatory bowel disease (IBD). METHODS: An open-label prospective and uncontrolled multicentre 6 month trial of MMF in combination with steroids was conducted in 24 chronic active IBD patients. A daily steroid demand of >/= 10 mg prednisone in the preceding 2 months and a Crohn's disease activity index (CDAI) > 150, or moderate to severe activity according to Truelove, served as criteria for chronic activity. The treatment consisted of a steroid pulse and tapering protocol in combination with MMF 2 g/day. A prednisone dose of 5 mg/day was maintained during months 4-6. The primary end-point was induction and maintenance of remission. RESULTS: Only 10 of 24 patients had achieved remission after 3 months. All but one Crohn's disease patient had relapsed by the end of the study at 6 months. Depression and migraine necessitated drug withdrawal in two patients. CONCLUSION: In conclusion, MMF 2 g/day was unable to induce and maintain remission for a period of 6 months in 23 of 24 chronic active IBD patients. Further controlled investigations are required in view of recent conflicting reports.

Adult↗

PubMed2000

Cultivatable microbial biodiversity: gnawing at the Gordian knot.

Rapid and inexpensive sorting of bacterial isolates may be achieved using Fourier transform infrared spectroscopy (FT-IR), a method that has hitherto been applied to identification and classification. The comprehensive characterization of environmental samples requires the isolation of large numbers of isolates using different growth media and growth conditions. In such cases, sorting the isolates is critical before isolates are subjected to more detailed studies. Using FT-IR, isolates are grown under standardized conditions, and 100 strains can be tested within less than 8 h. Chemotaxonomic and molecular characterization of members of clusters emerging from FT-IR analysis either at a level of spectral distance values below 20-30 (analysis of region 600-800 cm(-1), average linkage algorithm) or at spectral heterogeneity values below 75 (regions 1,200-900, 3,000-2,798 and 901-698, scaling to first region, Ward's algorithm) reveals great similarities in fatty acids and 16S rDNA sequences. As judged from riboprinting analyses and fatty acid analyses, FT-IR analysis is able to unravel intraspecific subclustering. The example used in this study of 100 isolates from a mat system, Lake Fryxell, Dry Valleys, Antarctica, selected from a larger number of isolates, picked mainly on the basis of colony pigmentation and form, reveals the utility of the method for identifying the number of putative species quickly. The method described is able to select strains rapidly that represent clusters at the specific and intraspecific level for subsequent characterization.

Arthrobacter↗

PubMed2000

IFN-gamma-induced change in microtubule organization and alpha-tubulin expression during growth inhibition of lung squamous carcinoma cells.

In cultures of KNS-62 cells derived from a human lung squamous cell carcinoma, the initial growth arrest in the continuous presence of interferon-gamma (IFN-gamma) turned to cytopathic effects after 2 days of treatment. The remaining viable cells showed grossly distorted morphology, with enlargement and extensions up to 5 cell diameters. The presence of apoptotic cells was shown 3 days after treatment with IFN-gamma. Immunocytochemically, the microtubular structures appeared augmented and highly aggregated. The level of alpha-tubulin-specific mRNA was distinctly increased after administration of IFN-gamma, and the amount of extractable alpha-tubulin protein was reduced. In parallel kinetics experiments, growth arrest by serum depletion or by contact inhibition during confluence resulted in reduced levels of alpha-tubulin-specific mRNA and in slightly elevated alpha-tubulin protein. The IFN-gamma-induced effects suggest interference with assembly or maintenance of the tubulin cable network, presumably associated with cell deformation and cytotoxicity.

Apoptosis↗

PubMed2000

Serum levels of stem cell factor in patients during transplantation of bone marrow or peripheral blood stem cells.

Stem cell factor (SCF) synergizes with other cytokines in vitro to stimulate the proliferation and differentiation of cells of the myeloid, megakaryocytic, erythroid, and lymphoid lineages. In vivo, it may play a role in engraftment after transplantation of bone marrow (BM) or peripheral blood stem cells (PBSC). Serum levels of SCF were closely monitored in 82 patients before and after allogeneic (n = 38), autologous (n = 6), or syngeneic (n = 1) BM transplantation (BMT) or autologous PBSC transplantation (PBSCT) (n = 37), respectively. SCF serum levels fluctuated around a mean in patients after allogeneic or autologous BMT or after PBSCT. In two patient subgroups (5 patients with acute myeloid leukemia [AML] and 6 patients with chronic myelogenous leukemia [CML]) with identical pretransplant conditioning regimen followed by allogeneic BMT, serum IL-6 levels significantly increased up to day +14 (p < 0.05). Correlation was not found between SCF serum levels and leukocyte or thrombocyte counts or the day of engraftment of these cell types. These data are a basis for further studies and constitute a further mosaic stone in understanding the changes in the complex cytokine network during engraftment.

Behavior Therapy↗

PubMed1999

The evolution of porcine reproductive and respiratory syndrome virus: quasispecies and emergence of a virus subpopulation during infection of pigs with VR-2332.

GP5, the principal envelope glycoprotein of porcine reproductive and respiratory syndrome virus (PRRSV), contains a hypervariable region within the ectodomain which is responsible for generating diversity in field isolates. The purpose of this study was to gain insight into the possible origin of this diversity by following GP5 sequence changes in pigs exposed to PRRSV strain VR-2332 in utero. A region of the PRRS virus genome containing portions of ORF4 and ORF5 was amplified directly from tissues of infected pigs from birth to 132 days of age. We observed the emergence of a new PRRSV population, identified by a single nucleotide change in the ectodomain. The Asp to Asn change at amino acid 34 was also found as a minor component in pigs that expressed the wild-type sequence. The results from this study suggest that the variability in the ectodomain of ORF5 is the result of positive or negative selection, of which the mechanism remains to be determined.

Amino Acid Sequence↗

PubMed1998

Strictureplasty with a pedunculated jejunal patch in Crohn's disease of the duodenum.

Surgical treatment for duodenal stenosis caused by Crohn's disease is only indicated in symptomatic duodenal obstruction when conservative treatment has failed. Previously described operative procedures include strictureplasty for short stenoses and bypass or resectional procedures, if duodenal stenosis is extensive. In this case of an extensive duodenal Crohn's stenosis, we performed a strictureplasty of the duodenum with a pedunculated jejunal patch. Thus, duodenal passage could be well preserved, and the patient has remained asyptomatic during a follow-up of more than 9 months.

Adult↗

PubMed1997

Inverse correlation of interleukin-6 with soluble interleukin-6 receptor after transplantation of bone marrow or peripheral blood stem cells.

The relationship between interleukin-6 (IL-6) and the soluble interleukin-6 receptor (sIL-6R) was analyzed in 1481 serum samples of 82 patients after bone marrow or peripheral blood cell transplantation. The cytokine and its soluble receptor were measured on a daily basis starting at day -3 before and ending at day 21 after transplantation. IL-6 serum levels increased after transplantation, were at a maximum at day 6 and returned to the baseline level thereafter. The levels of sIL-6R showed an inverse course with a minimum at day 6. Statistical analysis revealed a strong inverse correlation between IL-6 and sIL-6R with a weighted Spearman rank correlation coefficient of -0.53 (P < 0.001). IL-6 may play a role in the decrease of sIL-6R either by the direct inhibitory effect on the expression of the IL-6R gene or by formation of IL-6/sIL-6R complexes followed by their internalization in target cells.

Bone Marrow Transplantation↗

PubMed1996

Chronic basidiomycetous endophthalmitis after extracapsular cataract extraction and intraocular lens implantation.

BACKGROUND: Basidiomycetes are known as rare pathogens for meningitis, sinusitis, pneumonia, ulcerative lesions of the hard palate and onychomycosis. To our knowledge, no filamentous basidiomycete has been reported from a case of fungal endophthalmitis. PATIENT: We report on a 67-year-old man with delayed-onset endophthalmitis caused by an opportunistic basidiomycete. Tissue obtained during vitrectomy was cultured and examined by light and transmission electron microscopy. After enucleation the eye was examined by light microscopy. CONCLUSION: The patient had endophthalmitis from a sterile hyphomycete, harboured in remnants of lens capsule and a granuloma on the ciliary body. It was recognized as a Holobasidiomycete on the basis of its dolipore structure with perforated pore cap, seen with transmission electron microscopy. Species identification was not possible because fruiting bodies were absent. The patient failed to respond to intravitreal and systemic amphotericin B and systemic itraconazole. The eye was enucleated. This case demonstrates that filamentous basidiomycetes can cause endophthalmitis when inoculated during cataract extraction.

Aged↗

PubMed1996

Lactic acidosis and hypoglycemia in a patient with high-grade non-Hodgkin's lymphoma and elevated circulating TNF-alpha.

A 71-year-old patient with high-grade non-Hodgkin's lymphoma stage IVB, severe lactic acidosis and tumor-associated hypoglycemia is described. Endocrine causes of hypoglycemic episodes were excluded because of low serum concentrations of insulin and "insulin-like growth factor 1", and normal concentrations of growth hormone and thyroid hormone. Clinical conditions associated with lactic acidosis such as diabetes mellitus, biguanide intoxication, septicemia, acute hypoxemia, or circulatory insufficiency were ruled out. Enhanced glucose metabolism within the tumor was visualized by positron emission tomography employing 2-fluro-2-deoxy-D-glucose (FDG) as a tracer. A markedly elevated tumor necrosis factor-alpha (TNF-alpha) level was found which decreased after cytoreductive therapy paralleling the normalization of serum lactate. In contrast to the majority of cases of lymphoma-associated lactic acidoses reviewed to date, in our case lactate elimination was not reduced.

Acidosis, Lactic↗

PubMed1996

Serum interleukin-6 levels during bone marrow transplantation: impact on transplant-related toxicity and engraftment.

The biological properties of IL-6 include the induction of acute phase proteins, stimulation of hematopoietic stem cell growth and thrombopoiesis. Serum levels of IL-6 were closely monitored in 66 patients before and after allogeneic (n = 37), autologous bone marrow transplantation (n = 8) or autologous peripheral blood stem cell transplantation (n = 21). Almost every patient showed elevated IL-6 serum levels during the aplastic phase. Patients then suffered from mucositis, had elevated C-reactive protein (CRP) and usually body temperatures of above 38 degrees C. It was investigated whether IL-6 serum levels, apart from inducing acute phase reactions, correlated with transplant-related complications or leukocyte and thrombocyte engraftment. By statistical analysis, a correlation was found between IL-6 and CRP and between IL-6 and fever. In contrast, no correlation was found between IL-6 and elevated serum bilirubin as a marker for hepatotoxicity. IL-6 showed a weak negative correlation with leukocyte or platelet counts. In contrast, the day of platelet engraftment correlated with the day of peak serum IL-6 value, possibly indicating an influence of IL-6 on platelet engraftment.

Bilirubin↗