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A Weimann

Publications and source records attributed to A Weimann.

82 records · Page 5Linked to original sources
PubMed1987

Detection of oxygen activation and determination of the activity of antioxidants towards reactive oxygen species by use of the chemiluminigenic probes luminol and lucigenin.

Reactive oxygen metabolites can transfer, via oxygenation, the chemiluminigenic probes luminol and lucigenin to an excited state and thus induce light emission from these probes. This technique has been applied to a study of the effect of common food antioxidants on the availability of reactive oxygen species in aqueous model systems and in microsomal preparations. In all systems tested, propyl gallate and its congener octyl gallate proved to be the most active scavengers of the oxygenating species involved in the chemiluminescence reaction. In aqueous model systems, butylated hydroxyanisole was 10 times less efficient than the gallic acid ester antioxidants. In biological material, the lower scavenger activity of butylated hydroxyanisole is further compromised by its ability to induce a marked increase in production of hydrogen peroxide in the endoplasmic reticulum. Butylated hydroxytoluene is only marginally active in aqueous media and in biological material. It is concluded that gallic acid ester antioxidants may possess a significant protective potential towards toxic and carcinogenic agents due to their ability to remove toxic oxygen metabolites.

Acridines↗
PubMed1986

Detection of active oxygen in rat hepatocyte suspensions with the chemiluminigenic probe lucigenin.

The chemiluminigenic probe lucigenin has been employed to detect the production of active oxygen species in suspensions of intact rat hepatocytes. Light emission from lucigenin arises from oxygenation by superoxide anion; hydrogen peroxide or a species derived from it may contribute to the reaction. The inhibitory action of antioxidants on the availability of active oxygen species produced by hepatocytes was tested. Propyl gallate was the most potent inhibitor, butylated hydroxyanisole and butylated hydroxytoluene were less active. The latter compounds cause an alteration of the cell membrane at high concentrations.

Acridines↗
PubMed1984

Different efficiency of various synthetic antioxidants towards NADPH induced chemiluminescence in rat liver microsomes.

The chemiluminigenic probes luminol and lucigenin have been employed to study the production of reactive oxygen species during NADPH oxidation in microsomal preparations. Light emission obtained with lucigenin is 1,000 fold that obtained with luminol. Common food antioxidants differ widely in their ability to cope with microsomal oxygen activation. Propyl gallate proved to be the most potent chemiluminescence inhibitor among five compounds tested while butylated hydroxytoluene was virtually inefficient.

Acridines↗
PubMedDate not supplied

Role of liver transplantation in the treatment of unresectable liver cancer.

Resection remains the treatment of choice in liver cancer. In order to avoid liver transplantation in conventionally unresectable tumors ex-situ ("bench" procedure), in-situ and ante-situm resection technique should be preferred whenever feasible. Despite the deficiency of donor organs, a single center experience with 198 patients reveals that liver transplantation continues its role as a therapeutic option for selected patients. At present "favorable" indications for transplantation are International Union against Cancer (UICC) - stage II hepatocellular carcinoma as well as the subtype fibrolamellar carcinoma, uncommon tumors such as epitheloid hemangioendothelioma, hepatoblastoma, and liver metastases from neuroendocrine tumors. Due to unsatisfying results, intrahepatic bile duct-, stage III and IV hepatocellular carcinoma, hemangiosarcoma, and liver metastases from nonendocrine primaries should be excluded from liver transplantation alone. For these advanced tumors, especially in cases of extrahepatic involvement, a combination of liver transplantation and multivisceral resection has been proven feasible. However, a significant improvement in patient survival may only be expected only by currently investigated multimodality treatment protocols which will require further randomized studies.

Bile Duct Neoplasms↗
PubMedDate not supplied

Surgical treatment of cholangiocellular carcinoma.

Intrahepatic cholangiocellular carcinoma (CCC) is known to be associated with severe symptoms and a particularly poor prognosis. Nonsurgical methods have failed to change this situation up to now. Surgical therapy, so far, is the only chance for effective treatment, but it has had limited success. The relative infrequency of this tumor does not allow extensive statistics and limits our present knowledge. In this contribution the outcome of 50 patients who underwent liver resection or liver transplantation in our institution is reported. Their courses have been reevaluated according to pathohistologic classification and TNM tumor staging. The median survival rates were 12.8 months in the group of patients after liver resection (n = 32) and 5.0 months after liver transplantation (n = 18). Liver transplantation, however, was performed only in patients with unresectable tumors. The longest survival after transplantation was 25 months; after resection four patients survived more than 5 years. In the resection group and the transplantation group survival rates correlated with tumor size and tumor stages according to TNM, although the differences were not statistically significant. Liver resection thus has its place in resectable situations. Liver transplantation for unresectable lesions of this tumor type--always deemed critically in the past--seems not to be indicated with our present stage of knowledge, unless adjuvant protocols appear promising and are tested.

Bile Duct Neoplasms↗
PubMedDate not supplied

Benign liver tumors: differential diagnosis and indications for surgery.

The differential diagnosis for hemangioma, focal nodular hyperplasia (FNH), and hepatocellular adenoma may be difficult. Reliable diagnosis is mandatory for the decision of whether to apply surgery or observation. Experience with long-term observation in nonoperated patients with hemangioma and FNH is limited. A group of 437 patients from a single institution were analyzed with regard to a diagnostic algorithm, the indications for surgery, and observation. There were 238 hemangiomas, 150 cases of FNH, 44 adenomas, and 5 mixed tumors. Of the 437 patients, 173 underwent surgery; 103 with hemangioma and 54 with FNH were observed at our own institution, whereas 117 patients underwent follow-up elsewhere or were lost. Among the operated patients with confirmed histology, a good diagnostic yield was found for a combination of ultrasonography (US), contrast (bolus)-enhanced computed tomography (CT), and labeled red blood cell (RBC) scanning: sensitivity 85.7%, specificity 100%, positive predictive value (PPV) 100%, negative predictive value (NPV) 81.8%, and accuracy 91.3%. For FNH and combination of US and CT plus cholescintigraphy showed a sensitivity 82.1%, specificity 97.1%, PPV 95.8%, NPV 84.6%, and accuracy 90.3%. Surgical mortality was 0.6%. Observation of patients with hemangioma and FNH for a median of 32 months revealed no increase in tumor size in 80% and a decrease in fewer than 7%. There was no tumor rupture and no evidence of malignant transformation. We concluded that liver hemangioma and FNH can be differentiated from adenoma with high sensitivity, specificity, and accuracy by labeled RBC scanning and cholescintigraphy in combination with US and contrast-enhanced CT. In the case of symptoms or an equivocal diagnosis with respect to adenoma or hepatocellular carcinoma, surgery can be performed with very low risk. Because in asymptomatic patients with observed hemangioma or FNH no increase of tumor size can be expected for many years, the indications for surgery must be carefully evaluated.

Adenoma, Liver Cell↗
PubMedDate not supplied

Liver metastases of breast cancer: results of liver resection.

BACKGROUND: In case of distant metastases breast cancer is generally regarded as incurable. Therefore liver surgery is withheld from those patients, even in cases of isolated liver metastases. MATERIALS AND METHODS: Over 11 years we performed 35 liver resections in 34 patients with liver metastases of breast cancer. The median age was 47 years. The median interval between the primary operation and the liver resection was 27.3 months. 59% of the patients had a solitary metastasis. RESULTS: Curative (R0) resection was possible in 86%. Operative mortality was 3% (n = 1). Overall 5-year survival was 18.4% (median 27 months). Prognosis was significantly (p < 0.001) better following R0-resection (22%, median 41.5 months) than after R1/2-resection (maximum 20 months, median 5 months). Beside the radicality an unfavorable influence on the prognosis could be demonstrated only for a prior local recurrence of the primary tumor (p < 0.05). Other factors like stage of the primary tumor and number and size of the metastases were without prognostic significance. CONCLUSIONS: Patients with isolated liver metastases of breast cancer may have a long lasting benefit from liver resection. In individual cases cure may be possible.

Adult↗