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Biomedical subjects

Robert Koch

Publications and source records attributed to Robert Koch.

7 recordsLinked to original sources
PubMed2006

Long-term outcome of endoscopic treatment of biliary strictures after liver transplantation.

Biliary strictures are one of the most common complications following liver transplantation (LT), with an incidence of 5.8-34%. Endoscopic techniques have been successfully used to treat biliary complications; however, the long-term efficacy and safety of this treatment option has not yet been fully elucidated. This prospective study was performed to determine the efficacy and safety of endoscopic management of biliary complications after LT and its impact on long-term patient and graft survival. Biliary strictures were suspected in the presence of elevated liver parameters and/or abnormal abdominal sonography and subsequently diagnosed by endoscopic retrograde cholangiography (ERC). The mean follow-up was 39.8 (range, 0.3-98.2) months after first ERC. Between October 1992 and December 2003, a total of 515 patients underwent LT. Biliary complications were diagnosed in 84 patients (16.3 %). Anastomotic strictures (AS) alone were found in 65 (12.6%) and nonanastomotic strictures (NAS) in 19 patients (3.7%). Long-term success was observed in 77% of patients with AS. In patients with NAS, partial long-term responses could be achieved in 63% of patients. Five patients (6.2%) required a percutaneous and 6 (7.4%) patients a surgical approach. In conclusion, the long-term outcome for patients with post-liver transplant biliary strictures after endoscopic treatment is excellent, especially for patients with AS. Development of NAS reduces graft but not patient survival after endoscopic therapy.

Adult↗
PubMed2004

Virus dynamics and immune responses during treatment in patients coinfected with hepatitis C and HIV.

Mathematical modeling of the biological effect of interferon on virus decay permits the quantification of the efficacy (epsilon) of blocking virion production in different patient populations. The viral dynamic and immunologic responses of hepatitis C virus (HCV) infection to daily interferon therapy were characterized in twelve patients co-infected with human immunodeficiency virus (HIV). Three out of the twelve patients (25%) achieved an early viral response, a two-log reduction in HCV RNA by week 12. The mean epsilon of IFN-alpha in blocking HCV and HIV production were 72% and 74%, respectively. For HCV epsilon was highest (97%) in the one patient who had a sustained viral response, while it was reduced in the other two patients (68% and 77%). Baseline HCV RNA and the number of CD3+CD56+16+ cells were inversely related (r = -0.89, p = 0.03), and baseline HCV-specific immune responses were significantly higher in the three patients with 2-log viral load reductions. These data suggest that: 1) interferon efficacy at blocking virion production is correlated with treatment outcome in HIV/HCV co-infected patients, 2) that immunodeficient patients can respond to standard IFN-alpha, 3) that both innate and adaptive immune responses may be important determinants of HCV RNA decline in response to interferon.

Adult↗
PubMed2003

Posttraumatic splenic artery aneurysm presenting as occult gastrointestinal bleeding.

A 53-year-old man presented with a 19-month history of gastrointestinal bleeding. Repeated endoscopic investigation of the upper and lower intestine showed no source of bleeding. When the patient collapsed due to massive gastrointestinal hemorrhage he was referred to our center. Gastroscopy showed a large, bulging tumor protruding from the posterior gastric wall. The consistency of this tumor was soft and the overlying mucosa appeared smooth and intact. Endoscopic ultrasound and contrast-enhanced computerized tomography scan identified a partly thrombosized splenic artery aneurysm (SAA). Arteriography of the celiac trunk confirmed the SAA diagnosis; the SAA was subsequently occluded by coils. So far, four months after discharge, the patient is in excellent health and no further episode of gastrointestinal bleeding has occurred. SAA is a very rare cause of upper gastrointestinal bleeding, but it must be considered when no other common bleeding source can be detected.

Accidents, Traffic↗
PubMed2003

The aminoglycoside 6'-N-acetyltransferase type Ib encoded by Tn1331 is evenly distributed within the cell's cytoplasm.

The multiresistance transposon Tn1331, which mediates resistance to several aminoglycosides and beta-lactams, includes the aac(6')-Ib, aadA1, bla(OXA-9), and bla(TEM-1) genes. The nucleotide sequence of aac(6')-Ib includes a region identical to that of the bla(TEM-1) gene. This region encompasses the promoter and the initiation codon followed by 15 nucleotides. Since there were three possible translation initiation sites, the amino acid sequence at the N terminus of the aminoglycoside 6'-N-acetyltransferase type Ib [AAC(6')-Ib] was determined and was found to be SIQHF. This result indicated that aac(6')-Ib includes a translational fusion: the first five amino acids of the leader peptide of the TEM beta-lactamase are fused to the rest of the AAC(6')-Ib protein. This gene fusion could have formed during the genesis of Tn1331 as a consequence of the generation of a 520-nucleotide duplication (M. E. Tolmasky, Plasmid 24:218-226, 1990). An identical gene isolated from a Serratia marcescens strain has been previously described (G. Tran van Nhieu and E. Collatz, J. Bacteriol. 169:5708-5714, 1987). Extraction of the periplasmic proteins of E. coli harboring aac(6')-Ib by spheroplast formation showed that most of the AAC(6')-Ib protein is present in the cytoplasm. A genetic fusion to phoA confirmed these results. AAC(6')-Ib was shown to be evenly distributed inside the cell's cytoplasm by fluorescent microscopy with an AAC(6')-Ib-cyan fluorescent protein fusion.

Acetyltransferases↗
PubMedDate not supplied

Mechanisms of iron mediated regulation of the duodenal iron transporters divalent metal transporter 1 and ferroportin 1.

Intestinal iron absorption is regulated by the body's demands for iron. Identification of divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) has improved our understanding of iron transport across the intestinal epithelium. Although DMT1 and FPN1 mRNA bear an iron responsive element (IRE) within its untranslated regions which should cause susceptibility to iron mediated posttranscriptional regulation the latter has not been shown so far. The effects of iron perturbations on DMT1 and FPN1 expression were investigated in CaCo2 cells and in primary tissue cultures of human duodenal biopsies by means of Northern Blot, Western Blot, RNA-bandshift and Nuclear Run off analysis. Both DMT1 and FPN1 mRNA levels were increased upon treatment of CaCo2 cells with desferrioxamine, whereas iron treatment resulted in the opposite effect. These changes were paralleled by the respective alterations in DMT1 and FPN1 protein expression. Although desferrioxamine treatment increased the binding affinity of iron regulatory protein-1 to DMT1- and FPN1-IRE, the mRNA half life of DMT1 mRNA remained unchanged. Nuclear run-off analysis then demonstrated that the effects of iron and desferrioxamine on DMT1 and FPN1 mRNA expression are rather due to modulation of transcription of these genes. Our results demonstrate that iron unidirectionally regulates the expression of the two ferrous ion transporters DMT1 and FPN1 by affecting their transcription. This provides evidence for a negative feed-back loop between intracellular iron availability and transmembrane iron transport.

Caco-2 Cells↗