PubMed Health⌕ Search

Biomedical subjects

K Orth

Publications and source records attributed to K Orth.

At least 55 records · Page 3Linked to original sources
PubMed1996

Molecular ordering of the cell death pathway. Bcl-2 and Bcl-xL function upstream of the CED-3-like apoptotic proteases.

Genetic analyses of Caenorhabditis elegans has identified three genes that function in the regulation of nematode cell death. Mammalian homologs of two of these genes, ced-9 and ced-3, have been identified and comprise proteins belonging to the Bcl-2 and ICE families, respectively. To date, it is unclear where the negative regulators, ced-9 and bcl-2, function relative to the death effectors, ced-3 and the mammalian ced-3 homologs, respectively. Here, the molecular order of the cell death pathway is defined. Our results establish that Bcl-2 and Bcl-xL function upstream of two members of the ICE/CED-3 family of cysteine proteases, Yama (CPP32/apopain) and ICE-LAP3 (Mch3).

Amino Acid Sequence↗
PubMed1995

A transforming growth factor beta receptor type II gene mutation common in colon and gastric but rare in endometrial cancers with microsatellite instability.

We have recently demonstrated that mutation of the transforming growth factor-beta (TGF-beta) receptor type II (RII) gene is characteristic of colon cancers exhibiting microsatellite instability or replication errors (RER+). Moreover, we have shown that RII mutations in these RER+ colon cancers are characteristically frameshift mutations within a 10-bp polyadenine repeat present in the RII-coding region. We now show that RII gene mutations in this polyadenine repeat are also commonly present in RER+ gastric cancers (71%). In contrast, we find these same RII gene mutations are distinctly uncommon in RER+ endometrial cancers (17%, P < 0.02). These results suggest that RII gene mutations confer a growth advantage and are selected for in RER+ cancers of both the upper and lower gastrointestinal tract. The genesis of RER+ endometrial tumors must, however, be by a different route.

Base Sequence↗
PubMed1995

[Photodynamic therapy of small adenocarcinomas with methylene blue].

Photodynamic therapy (PDT) is a new method in the treatment of small/early malignancies. It is based on the interaction of a photosensitiser, light and cellular oxygen. A new therapeutic concept with locally applied 1% of methylene blue into the tumour and subsequent radiation (argon laser pumped dye laser, 665 nm, 100 mW/cm2, 100 J/cm2) was first tested in xeno-transplanted carcinomas and then clinically applied. The animal experiments showed a tumour volume reduction of 1:12, as compared to a control group, two weeks after the first PDT-application. After the second PDT-treatment 6 out of 10 tumours were destroyed. Four carcinomas showed inhibited growth after the treatment. The method was clinically applied in 3 patients with local tumour recurrence in the area of the anastomosis after oesophagus resection. 72 hours after PDT-treatment 4-5 mm tumour necrosis could be proven experimentally. PDT was repeated at the same site within 2 weeks. There were no experimental or clinical complications during or after PDT. The treated tumour areas showed no local tumour growth within 6 months after PDT-treatment.

Adenocarcinoma↗
PubMed1994

Genetic instability in human ovarian cancer cell lines.

We have analyzed the stability of microsatellites in cell lines derived from human ovarian cancers and found that 5 out of 10 of the ovarian tumor cell lines are genetically unstable at the majority of the loci analyzed. In clones and subclones derived serially from one of these cell lines (2774; serous cystadenocarcinoma), a very high proportion of microsatellites distributed in many different regions of the genome change their size in a mercurial fashion. We conclude that genomic instability in ovarian tumors is a dynamic and ongoing process whose high frequency may have been previously underestimated by PCR-based allelotyping of bulk tumor tissue. We have identified the source of the genetic instability in one ovarian tumor as a point mutation (R524P) in the human mismatch-repair gene MSH2 (Salmonella MutS homologue), which has recently been shown to be involved in hereditary nonpolyposis colorectal cancer. Patient 2774 was a 38-year-old heterozygote, and her normal tissue carried both mutant and wild-type alleles of the human MSH2 gene. However the wild-type allele was lost at some point early during tumorigenesis so that DNA isolated either from the patient's ovarian tumor or from the 2774 cell line carries only the mutant allele of the human MSH2 gene. The genetic instability observed in the tumor and cell line DNA, together with the germ-line mutation in a mismatch-repair gene, suggest that the MSH2 gene is involved in the onset and/or progression in a subset of ovarian cancer.

Adult↗
PubMed1994

Low density lipoprotein receptor-related protein is necessary for the internalization of both tissue-type plasminogen activator-inhibitor complexes and free tissue-type plasminogen activator.

Tissue-type plasminogen activator (t-PA) is used as a thrombolytic agent in treatment of myocardial infarction. However, large doses of this agent must be administered in treatment to maintain a thrombolytic state because t-PA is cleared rapidly from circulation. We designed specific ligands to distinguish between two major mechanisms by which t-PA is taken into cells and degraded. One of these mechanisms involves internalization of complexes between t-PA and its cognate inhibitor plasminogen activator inhibitor type-1 (PAI-1); the other mechanism is independent of PAI-1. Using specific inhibitors for low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor (LRP), we show that the degradation by hepatocytes of both free t-PA and t-PA.PAI-1 complexes involve the receptor LRP. We demonstrate that fibroblasts degrade both free t-PA (PAI-1-independent) and t-PA complexed with its specific inhibitor PAI-1 (PAI-1-dependent), whereas genetically altered fibroblasts that do not express LRP neither internalize nor degrade these ligands. We also show that a PAI-1-independent, t-PA ligand can inhibit the degradation of both free t-PA and t-PA.PAI-1 complexes. We propose LRP is the receptor for both PAI-1-independent and PAI-1-dependent t-PA ligands.

Amino Acid Sequence↗
PubMed1994

Molecular dissection of ligand binding sites on the low density lipoprotein receptor-related protein.

The low density lipoprotein receptor-related protein (LRP) is a large multifunctional receptor that is involved in the cellular uptake of a number of functionally diverse ligands including apoE-rich remnant lipoproteins, lipoprotein lipase, alpha 2-macroglobulin-protease complexes, plasminogen activator-inhibitor complexes, and the active protease tissue-type plasminogen activator. Ligand binding and competition experiments suggest that most LRP ligands bind to specific, independent sites on the large 515-kDa subunit of the receptor. In a previous study (Moestrup, S.K., Holtet, T.L., Etzerodt, M., Thøgersen, H.C., Nykjaer, A., Andreasen, P.A., Rasmussen, H.H., Sottrup-Jensen, L., and Gliemann, J. (1993) J. Biol. Chem. 268, 13691-13696), ligand blotting was used to localize the binding sites for urokinase-type plasminogen activator-plasminogen activator inhibitor-1 (PAI-1) complexes and for alpha 1-macroglobulin to a proteolytic fragment of LRP containing the second cluster of complement-type cysteine-rich repeats. Here, we have used a recombinant DNA approach to express functionally restricted chimeric "LRP-minireceptors" containing two different regions of the extracellular domain of the receptor in cultured cells. Receptor-associated protein, a negative modulator of LRP activity, is bound and internalized by cells transfected with either construct. A minireceptor containing the cluster of eight complement-type cysteine-rich repeats followed by four epidermal growth factor precursor homologous domains binds and internalizes 125I-labeled plasminogen activator-PAI-1 complexes. It also mediates the cellular uptake of the uncomplexed protease tissue-type plasminogen activator (tPA), suggesting that the tPA and PAI-1 binding sites on LRP are in close vicinity and might promote cooperative binding of tPA-PAI-1 complexes. However, alpha 2-macroglobulin is not internalized by this minireceptor suggesting that this ligand requires the presence of a single epidermal growth factor-repeat which is contained in the previously studied proteolytic fragment but is absent from the minireceptor.

Animals↗
PubMed1994

Photodynamic therapy of experimental colonic tumours with 5-aminolevulinic-acid-induced endogenous porphyrins.

5-Aminolevulinic acid (5-ALA) is a precursor in the biosynthesis of haem. External application of 5-ALA leads to the formation of protoporphyrin IX, the last intermediate product before haem, which is an effective sensitiser. The 5-ALA-induced endogenous photosensitisation of tumour cells has been exploited for photodynamic therapy (PDT). Experimental human G-3 colonic tumours were transplanted into nude mice, and ten mice were treated by PDT. Ten animals served as controls. We measured a fluorescence intensity of the tumour that was about eight times higher than in the surrounding tissue; a good correlation between the fluorescence intensity and the photodynamic effect was found. Tumour growth was inhibited significantly after PDT, two tumours being destroyed completely after the second PDT treatment. In addition, on-line fluorescence detection during PDT showed a change in the intensity and the fluorescence spectrum of protoporphyrin IX caused by photobleaching and the formation of photoproducts.

Adenocarcinoma↗
PubMed1994

[The value of various ultrasound criteria in objective assessment of acute reactive cholecystitis. A prospective follow-up study of ventilated intensive care patients].

Ultrasound of the abdomen was performed in 30 artificially respirated patients under intensive care conditions for 7 days per patient over a time period of 6 months to elucidate the therapeutic value of different ultrasonographic findings with respect to the diagnosis "reactive acute cholecystitis". Our results show, that neither the detection of concrements or sludge within the gallbladder, nor the transient dilatation of the bile duct, nor a transient wall-thickening or the occurrence of a three-layered wall of the gallbladder can be interpreted as reliable sonographic criteria for the occurrence of an acute reactive cholecystitis. From this we conclude, that reactive acute cholecystitis leading to the indication for cholecystectomy can only be diagnosed from the combination of clinical and sonographic findings. However, reactive acute cholecystitis can almost certainly be excluded, even in obscure upper abdominal symptoms, when the sonogram of the gallbladder is normal.

Acute-Phase Reaction↗
PubMed1992

Low density lipoprotein receptor-related protein and gp330 bind similar ligands, including plasminogen activator-inhibitor complexes and lactoferrin, an inhibitor of chylomicron remnant clearance.

The low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor (LRP) and gp330, two members of the low density lipoprotein receptor gene family, share a multitude of cysteine-rich repeats. LRP has been shown to act as an endocytosis-mediating receptor for several ligands, including protease-antiprotease complexes and plasma lipoproteins. The former include alpha 2-macroglobulin-protease complexes and plasminogen activator inhibitor-activator complexes. The latter include chylomicron remnant-like particles designated beta-very low density lipoproteins (beta-VLDL) complexed with apoprotein E or lipoprotein lipase. The binding specificity of gp330 is unknown. In the current studies we show that gp330 from rat kidney membranes binds several of these ligands on nitrocellulose blots. We also show that both LRP and gp330 bind an additional ligand, bovine lactoferrin, which is known to inhibit the hepatic clearance of chylomicron remnants. Lactoferrin blocked the LRP-dependent stimulation of cholesteryl ester synthesis in cultured human fibroblasts elicited by apoprotein E-beta-VLDL or lipoprotein lipase-beta-VLDL complexes. Cross-competition experiments in fibroblasts showed that the multiple ligands recognize at least three distinct, but partially overlapping sites on the LRP molecule. Binding of all ligands to LRP and gp330 was inhibited by the 39-kDa protein, which co-purifies with the two receptors, suggesting that the 39-kDa protein is a universal regulator of ligand binding to both receptors. The correlation of the inhibitory effects of lactoferrin in vivo and in vitro support the notion that LRP functions as a chylomicron remnant receptor in liver. LRP and gp330 share a multiplicity of binding sites, and both may function as endocytosis-mediating receptors for a large number of ligands in different organs.

Animals↗
PubMed1992

Complexes of tissue-type plasminogen activator and its serpin inhibitor plasminogen-activator inhibitor type 1 are internalized by means of the low density lipoprotein receptor-related protein/alpha 2-macroglobulin receptor.

Tissue-type plasminogen activator and urokinase are serine proteases secreted by many cell types that participate in biological processes, such as tissue restructuring, cell migration, and tumor metastasis. Clinically, these proteases are used to dissolve coronary fibrin clots that are the proximal causes of acute myocardial infarction. In vivo, the activity of these enzymes is controlled by plasminogen-activator inhibitors, members of the serpin family of protease inhibitors. This study shows that tissue-type plasminogen activator-inhibitor complexes bind in solution to low density lipoprotein receptor-related protein (LRP), a large heterodimeric ubiquitous membrane receptor. In cultured cells, endocytosis and degradation of these complexes is reduced by polyclonal antibodies directed against LRP and inhibited by a M(r) 39,000 protein that binds to LRP and inhibits its interaction with previously known ligands, including apolipoprotein E and alpha 2-macroglobulin. We propose a role for LRP in the clearance of plasminogen activator-inhibitor complexes that is analogous to its function in the endocytosis of alpha 2-macroglobulin-protease complexes.

Animals↗
PubMed1992

Tyrosine 67 in the epidermal growth factor-like domain of tissue-type plasminogen activator is important for clearance by a specific hepatic receptor.

Human tissue-type plasminogen activator (t-PA) is cleared rapidly from the circulation by hepatic receptors, one of which recognizes a site in the epidermal growth factor-like domain of the molecule. To define this site more precisely, we have used oligonucleotide-mediated mutagenesis to introduce amino acid substitutions at specific positions located in turns that connect antiparallel beta-sheets in the epidermal growth factor-like domain. Mutated t-PA proteins with amino acid substitutions of the tyrosine residue at position 67 showed markedly lower rates of endocytosis and degradation by cultured cells of the rat hepatoma (H4) line that express a specific receptor for t-PA, and their half-life in the circulation of rats was extended significantly because of a reduction in the rate of the rapid alpha-phase of clearance. The enzymatic properties and fibrinolytic activity of these mutants in vitro were not significantly different from those of wild-type t-PA. We conclude that tyrosine 67 comprises a key determinant in the clearance of t-PA by a specific hepatic receptor.

Amino Acid Sequence↗
PubMed1992

[Cryotherapy in rectal cancer. A palliative local tumor treatment].

Cryotherapy was applied to 182 rectal cancer patients in the Department of General Surgery, University of Ulm, between 4/1982 and 4/1991. Recipients of this tumor freezing therapy were patients whose general condition was bad, patients with an advanced inoperable carcinoma, patients with tumor recurrence and patients refusing operation. Rectal carcinomas, mostly in an advanced stage, were usually freezed several times. Only 4 patients with general inoperability reached the survival time margin of 5 years. In 18 patients local tumor destruction was possible by application of cryotherapy. In 80% of cases disagreeable tumor symptoms like tenesma, mucous discharge and oozing hemorrhages could be reduced or completely removed. Perianal pain and intense tumor bleeding could be relieved temporarily or definitely in only 50% of patients. An artificial anus could be avoided in 80% of cases by local tumor destruction/reduction or arrest of tumor growth. The mean survival time of patients with tumor recidivation was 11 months after onset of the recurrence. Tumor progression, incontinence and iatrogenic rectal perforation made an artificial anus necessary in 14 patients.

Aged↗
PubMed1992

[Surgical therapy of acute cholecystitis--advantages of early operation].

229 patients with an acute cholecystitis were operated on at the Surgical University Hospital of Ulm between 3/1982 and 6/1990. 42.3% of the patients were older than 70 years, the mean age being 64.3 years. 51.5% suffered from a complicated form of the disease. Intercurrent diseases were preoperatively found in 76%. Intraoperative complications of a technical nature occurred in 3.1%. The overall postoperative morbidity rate was 54%, with 9.4% of local problems, and showed a clear dependency on age and the number of preexisting risk factors. 31% had to undergo reoperation. The overall mortality rate was 2.6%, with a 0% mortality for patients under 65 years. The number of preexisting risk factors clearly correlated the period of hospitalisation, which was 16.1 days on average. In symptomatic gallstone diseases an early elective cholecystectomy should be strongly considered, especially in aged and multimorbid patients.

Acute Disease↗
PubMed1992

Increased incidence of gallstones and prior cholecystectomy in patients with large bowel cancer.

In a retrospective study, the frequency of occurrence of gallstones and cholecystectomy in 479 patients with colorectal cancer was compared with that of 483 matched control patients with other malignancies. The mean interval between cholecystectomy and colon cancer diagnosis was 15.1 +/- 9.9 yr (range 2-53 yr), and there was no statistically significant difference, compared with the control group at 13.9 +/- 8.2 yr (range 2-31 yr). In patients with colon cancer, the general increased relative risk of concomitant diagnosed gallstones (relative risk 1.73, p = 0.0123) and the relative risk of cholecystectomy (relative risk 2.08, p = 0.0074) was statistically significant. However, when the data with regard to sex were analyzed, significant differences were observed only in women. Women affected by right colon cancer also had a statistically significant higher incidence of previous cholecystectomy (relative risk 2.86, p = 0.0096), but no significantly higher incidence of concomitant gallstones. The general increased relative risk in patients with right colon cancer and decreased risk in patients with left colon cancer of concomitant gallstones and prior cholecystectomy was statistically significant. Our data provide evidence for the hypothesis that both gallstones and cholecystectomy increase the general risk of large bowel cancer. Therefore, they are also compatible with the possibility that common risk factors causes the association between gallstones and large bowel cancer.

Aged↗
PubMed1992

[Laparoscopic cholecystectomy versus mini-lap-cholecystectomy. Results of a prospective, randomized study].

Laparoscopic cholecystectomy (LCCE) was gaining acceptance rapidly, when several institutions could demonstrate the safety of this minimal invasive treatment modality. Nevertheless prospective randomised studies still are missing to prove the advantages of this new treatment modality in contrast to open cholecystectomy. 77 patients with symptomatic cholelithiasis were treated by LCCE (n = 40) or mini-lap CCE (n = 37) in a prospective, randomised study. As preliminary results, there were no differences in duration of anesthesia and operation time, perioperative complications or postoperative need for analgetics. Patients with LCCE had significant less postoperative pain, less restriction of total vital capacity and a shorter postoperative hospital stay as parameters of a diminished operative trauma.

Cholecystectomy↗
PubMed1991

Expression and characterization of recombinant human acyloxyacyl hydrolase, a leukocyte enzyme that deacylates bacterial lipopolysaccharides.

The molecular cloning and eukaryotic cell expression of the complementary DNA for human neutrophil acyloxyacyl hydrolase (AOAH) are described. AOAH is a leukocyte enzyme that selectively removes the secondary (acyloxyacyl-linked) fatty acyl chains from the lipid A region of bacterial lipopolysaccharides (endotoxins), thereby detoxifying the molecules. The two disulfide-linked subunits of the enzyme are encoded by a single mRNA. The amino acid sequence of the protein contains a lipase consensus sequence in the large subunit and a region in the small subunit that is similar to the saposins, cofactors for sphingolipid hydrolases. The recombinant enzyme, like native AOAH, hydrolyzes secondary acyl chains from more than one position on the lipopolysaccharide backbone. Acyloxyacyl hydrolase is a novel two-component lipase that, by deacylating lipopolysaccharides, may modulate host inflammatory responses to Gram-negative bacterial invasion.

Acylation↗