Biomedical subjects

S Schären

Publications and source records attributed to S Schären.

5 recordsLinked to original sources

PubMed2004

Vertebral osteomyelitis caused by non-tuberculous mycobacteria.

Vertebral osteomyelitis caused by non-tuberculous mycobacteria is a rare disease, with only 31 cases and one nosocomial outbreak reported in the literature (MedLine review between 1965 and December 2003). The clinical features are often indistinguishable from those of pyogenic osteomyelitis. Early diagnosis of such infections is a major challenge because of the slow growth of these microorganisms. No consensus guidelines for the treatment of these infections exist. Prolonged anti-mycobacterial therapy in combination with surgical debridement is recommended.

Adolescent↗

PubMed2001

One of two hemN genes in Bradyrhizobium japonicum is functional during anaerobic growth and in symbiosis.

Previously, we screened the symbiotic gene region of the Bradyrhizobium japonicum chromosome for new NifA-dependent genes by competitive DNA-RNA hybridization (A. Nienaber, A. Huber, M. Göttfert, H. Hennecke, and H. M. Fischer, J. Bacteriol. 182:1472-1480, 2000). Here we report more details on one of the genes identified, a hemN-like gene (now called hemN(1)) whose product exhibits significant similarity to oxygen-independent coproporphyrinogen III dehydrogenases involved in heme biosynthesis in facultatively anaerobic bacteria. In the course of these studies, we discovered that B. japonicum possesses a second hemN-like gene (hemN(2)), which was then cloned by using hemN(1) as a probe. The hemN(2) gene maps outside of the symbiotic gene region; it is located 1.5 kb upstream of nirK, the gene for a Cu-containing nitrite reductase. The two deduced HemN proteins are similar in size (445 and 450 amino acids for HemN(1) and HemN(2), respectively) and share 53% identical (68% similar) amino acids. Expression of both hemN genes was monitored with the help of chromosomally integrated translational lacZ fusions. No significant expression of either gene was detected in aerobically grown cells, whereas both genes were strongly induced (> or = 20-fold) under microaerobic or anaerobic conditions. Induction was in both cases dependent on the transcriptional activator protein FixK(2). In addition, maximal anaerobic hemN(1) expression was partially dependent on NifA, which explains why this gene had been identified by the competitive DNA-RNA hybridization approach. Strains were constructed carrying null mutations either in individual hemN genes or simultaneously in both genes. All mutants showed normal growth in rich medium under aerobic conditions. Unlike the hemN(1) mutant, strains lacking a functional hemN(2) gene were unable to grow anaerobically under nitrate-respiring conditions and largely failed to fix nitrogen in symbiosis with the soybean host plant. Moreover, these mutants lacked several c-type cytochromes which are normally detectable by heme staining of proteins from anaerobically grown wild-type cells. Taken together, our results revealed that B. japonicum hemN(2), but not hemN(1), encodes a protein that is functional under the conditions tested, and this conclusion was further corroborated by the successful complementation of a Salmonella enterica serovar Typhimurium hemF hemN mutant with hemN(2) only.

Amino Acid Sequence↗

PubMed1999

[Atlas fractures].

Fractures of the atlas account for 1-2% of all vertebral fractures. We divide atlas fractures into 5 groups: isolated fractures of the anterior arch of the atlas, isolated fractures of the posterior arch, combined fractures of the anterior and posterior arch (so-called Jefferson fractures), isolated fractures of the lateral mass and fractures of the transverse process. Isolated fractures of the anterior or posterior arch are benign and are treated conservatively with a soft collar until the neck pain has disappeared. Jefferson fractures are divided into stable and unstable fracture depending on the integrity of the transverse ligament. Stable Jefferson fractures are treated conservatively with good outcome while unstable Jefferson fractures are probably best treated operatively with a posterior atlanto-axial or occipito-axial stabilization and fusion. The authors preferred treatment modality is the immediate open reduction of the dislocated lateral masses combined with a stabilization in the reduced position using a transarticular screw fixation C1/C2 according to Magerl. This has the advantage of saving the atlanto-occipital joints and offering an immediate stability which makes immobilization in an halo or Minerva cast superfluous. In late instabilities C1/2 with incongruency of the lateral masses occurring after primary conservative treatment, an occipito-cervical fusion is indicated. Isolated fractures of the lateral masses are very rare and may, if the lateral mass is totally destroyed, be a reason for an occipito-cervical fusion. Fractures of the transverse processes may be the cause for a thrombosis of the vertebral artery. No treatment is necessary for the fracture itself.

Bone Nails↗

PubMed1998

[Chronic back pain].

Low-back pain is a very common disease in Switzerland as elsewhere, with a prevalence of 65%. The pain is usually due to degeneration of the motion segment, but subsides spontaneously in some 95% of cases irrespective of the treatment. Only 5% of patients still have pain after one year; but account for over 80% of the costs due to low-back pain. Some patients can be helped by surgical fusion; however; preoperative identification of the pain source is mandatory. Since there is no consistent correlation between pain and the degree of degeneration of motion segments as seen on plain radiographs, functional radiographs, CT scan or MRI, other diagnostic methods such as facet blocks, discography and external diagnostic fixation must be used. After careful patient selection a fusion operation may be considered. Good results after fusion operations are reported in 60-80% of patients. The operative techniques are described.

Cost-Benefit Analysis↗

PubMed1993

[Acute pancreatitis after local infusion of divalent cations].

The association of hypercalcemia and acute pancreatitis had been experimentally reproduced in cats by local infusions of the divalent cation calcium whereas the monovalent cation potassium did not induce any pancreatic pathology. The purpose of the present study was therefore to investigate the role of further divalent cations in order to determine the relevance of ion valency for pancreatitis induction. Anesthetized male SIV-rats received divalent cations, of which a role in the pancreas had already been reported in the literature, through retrograde infusions into the splenic artery at a dose of 0.6 mmol/kgh for 3 hours and at a flow of 0.5-1.0 ml/h. The pancreas was then removed for morphologic studies. In the animals treated with calcium and manganese, pancreas showed a hemorrhagic necrosis of the acinar lobuli with leucocytic infiltrates. The barium treated animals spontaneously died after 49 +/- 15 minutes and revealed acute pancreatitis in the perfused, but not in the residual pancreas. Zinc at the initial dose induced an immediate heparin-refractory blood-clotting with subsequent ischemic necrosis whereas a lower dosis (0.002 mmol/kgh) led to an acute pancreatitis as seen after calcium. The magnesium treated animals and the controls did not reveal any pathology. We conclude that some divalent cations may induce an acute pancreatitis, but that the induction is not dependent on the cation valency.

Acute Disease↗