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Biomedical subjects

M Knoop

Publications and source records attributed to M Knoop.

At least 55 records · Page 3Linked to original sources
PubMed1995

The effect of temporary hepatic ischemia on liver surface pH and potassium ion activity in the rat.

The effects of hepatic ischemia can be analyzed with a wide variety of functional and morphological methods. In this study we used a new organ monitoring device that accurately determines pH and K+ activities on the liver surface with ion-selective electrodes. Four groups of rats (n = 6 each) were subjected to complete, arterial or portal warm ischemia for 15 min (achieved by clamping of the hepatoduodenal ligament, the hepatic artery or the portal vein) and subsequent reperfusion. One group was sham-operated. Complete and portal ischemia were characterized by an immediate decline of pH and a more retarded rise of K+ activity on the liver surface. Arterial ischemia had almost no effect on these two parameters when compared with the sham group. Upon reperfusion the shifts of pH and K+ activity reversed towards initial baseline values. The organ monitoring system offers the option to assess ional shifts non-invasively during organ procurement, ischemia and reperfusion and may be used as an additional criterion for the estimation of organ viability.

Acid-Base Equilibrium↗
PubMed1995

[Extended partial Kausch-Whipple duodenopancreatectomy by resection of tumor infiltrated vascular segments].

AIM: Vessel infiltration of the portal vein is often considered as contraindication for pancreas resection for carcinoma. In this retrospective analysis we investigated if an extended Whipple's procedure including vessel resection submits the patient to a significantly higher risk. PATIENTS AND METHODS: From August 1985 until February 1994 179 Whipple's procedures were carried out, in 74 cases for carcinoma of the pancreatic head. In this group 26 patients were classified as stage I (35.2%), 5 as stage II (6.7%), 38 as stage III (51.4%) and one patient as stage IV. In 18 cases a segment of the portal vein was resected, in 16 cases reconstructed by end-to-end anastomosis and in two cases by implantation of a GoreTex prosthesis. No special anticoagulation was applied. RESULTS: There were no anastomosis-related complications such as hemorrhage, thrombosis or stenosis. The lethality rate was 1.4% (1/74), insufficiencies at the pancreas and bile duct anastomosis occurred in 0% and 1.4% (1/74), resp. Patients with segmental vessel resection in stage III had a mean survival of 9 months and by 3 years there was no survivor compared to 11.7 months and 17% survival after 4 years in stage III without vessel resection. CONCLUSION: By performing vessel resection more pancreas tumors than earlier are resectable without increased risk. Since the results of oncologic alternative treatment modalities are still poor pancreas resection represents at present the best option for the patient.

Adult↗
PubMed1995

[Is liver abscess still an indication for liver resection?].

AIM: The standard therapy for liver abscesses consists of percutaneous drainage. In certain cases a liver resection may be indicated. The indication for liver resection in six patients with liver abscess is analysed retrospectively. METHODS: Between 7.7.87-13.10.93 six patients (4 male, 2 fem.) in the age of 40-72 years (mean 59 yrs.) underwent liver resection for liver abscess at our institution. The patients suffered from symptoms of a progressive liver abscess formation: fever, hepatomegaly, loss of weight, jaundice and anorexia. Abscess localization was performed preoperatively by ultrasound and CT. Drainage attempts were unsuccessful in these patients, resections were carried out for suspicion of malignancy or during a laparotomy due to other reasons. RESULTS: Liver resections were left and right hemihepatectomy (1x each), left lateral resection (3x) and one wedge resection. Intraoperative blood transfusion requirements were not different from those of other indications for resection. Postoperative hospitalization lasted 12-33 days (mean 19 days). The postoperative course was uneventful, in one case a hematoma at the resection site required drainage. CONCLUSION: Resection for liver abscesses is indicated only in exceptional cases but allows for definite therapy.

Adult↗
PubMed1995

[Graft-vs.-host reaction: a severe complication after orthotopic liver transplantation].

INTRODUCTION: Patients with solid-organ transplantation are at risk for Graft-versus-host disease (GVHD) even though GVHD is a rare phenomenon after orthotopic liver transplantation (OLT). CASE REPORT: The 30 yrs old male patient received an ABO compatible orthotopic liver graft for acute liver failure due to intoxication with amanita phalloides. Twenty-four days after OLT the patient developed high temperatures up to 40.0 degrees C and pancytopenia and was treated for CMV-infection. On postoperative day (POD) 32 an erythematous maculo-papular rash developed. A drug induced toxic epidermal necrolysis was suspected and treated with plasmapheresis for three days. Acute renal failure and respiratory insufficiency occurred while liver function was not impaired. A skin biopsy at that time showed no specific signs for GVHD. On POD 42 HLA-typing of circulating lymphocytes presented donor HLA phenotype and GVHD was established. Therapy with ATG was started but the clinical status of the patient did not improve. Following administration of OKT3 on POD 48 a reduction of activated CD-3 lymphocytes from 90% to 60% could be achieved. Due to the low platelet count the patient died of intracerebral hemorrhage on POD 52. CONCLUSION: Since a fully developed GVHD is rare after OLT and the similarity of the clinical findings to viral or drug induced diseases is high, diagnosis is often made late in the course of the disease. Furthermore, therapeutic measures for GVHD are scarce and diagnosis has to be established as early as possible, hence pretransplant procurement of donor and recipient mononuclear cells for later study should be considered to decrease the time period between clinical suspicion and diagnosis.

Adult↗
PubMed1994

Evidence of alloreactive T suppressor cells in the maintenance phase of spontaneous tolerance after orthotopic liver transplantation in the rat.

In the DA-->PVG rat strain combination liver allografts are spontaneously tolerated and induce a state of systemic tolerance towards donor antigens. Thirty long-term (> 100 days)-surviving liver recipients in this strain combination were used to study humoral and cellular mechanisms of tolerance in the maintenance phase after liver transplantation. In the popliteal lymph node assay splenocytes of liver grafted or native PVG rats displayed a similar proliferative response in (DAxPVG)F1 hybrid rats, indicating an unaffected capacity of these cells to mount graft-versus-host reactions. Using adoptive transfer assays T-splenocytes (1x10(7) cells, MRC Ox 19+, MRC Ox12-, CD 5) of long-term-surviving liver recipients were able to suppress the rejection of DA hearts (donor-specific), of DA and AO kidney grafts in irradiated (300 cGy) PVG recipients. Serum of long-term-surviving liver recipients was able to suppress the rejection of semiallogeneic (DAxPVG)F1 heart grafts after double injection of 1 ml serum, while fully allogeneic DA heart as well as skin and pancreaticoduodenal grafts were resistant to passive enhancement. The results confirm the development of spontaneous tolerance after liver grafting in the DA-->PVG strain combination, and the demonstration of T cells with suppressive capacity in adoptive transfer experiments indicates a role for T suppressor cells in the maintenance phase of spontaneous tolerance after liver grafting.

Animals↗
PubMed1994

Experience with cuff rearterialization in 600 orthotopic liver grafts in the rat.

The model of orthotopic rat liver transplantation has been a useful tool in transplantation research for two decades. Due to technical problems, the optional hepatic artery anastomosis is not performed in many experiments. Recently developed techniques, however, have made rearterialization a simple procedure. With our technique of cuff rearterialization to the recipient common hepatic artery, in 600 rat liver grafts we achieved high viability, and an early patency rate of 100%. Patency rates after 2 and 21 days were nearly 90%. Cuff rearterialization is simple, rapid to perform, and provides a physiologic model. Compared to strictly venous liver grafts, rearterialized grafts demonstrate improvement in survival, more rapid normalization of liver function parameters, a better preserved liver structure, and less biliary complications. Rearterialization is an important component of a physiologically relevant rat liver transplantation model, and non-specific changes due to arterial ischemia may adversely affect the interpretation of experimental data.

Anastomosis, Surgical↗
PubMed1994

The validity of the MEGX test in correlation with histology after orthotopic rat liver transplantation.

Lidocaine metabolism (MEGX test) as an indicator for liver function in the assessment of different degrees of liver disease and as a predictor for liver outcome after transplantation is well established. Since reduced liver function is associated with an alteration in parenchymal and non-parenchymal cells, we evaluated whether MEGX values correlate with histology in an in vivo model of orthotopic rat liver transplantation (ORLT) to assess histological damage without taking biopsy specimens. Livers from syngeneic Lewis rats were transplanted with rearterialization after 15-30 h of cold storage in UW solution and rinsing with Carolina Rinse Solution prior to implantation. Forty-eight hours after transplantation, the MEGX test was performed and metabolites were measured with a commercial kit as described elsewhere. Biopsy specimens were taken and graded three degrees of damage (mild, moderate, and severe) in a double blind fashion by a pathologist. MEGX values were assigned to the histological results. Statistical analyses were done with a Mann-Whitney test (n = 58) for mean values. The mean MEGX values attributed to histologies with a mild, moderate, severe degree of damage were 159.96, 78.46 and 44.42 ng/ml, respectively. When the histological groups were compared with the mean MEGX values, mild vs moderate, mild vs severe and moderate vs severe were significant (P - 0.0001). In conclusion, MEGX values correlate significantly with histological grading in a linear fashion after ORLT. The MEGX test may be of clinical value because it reflects the histological pattern of livers and may reduce the necessity to take biopsy specimens before and after transplantation.

Alanine Transaminase↗
PubMed1994

Incidence and clinical relevance of recurrent hepatitis C infection after orthotopic liver transplantation.

From September 1988 to November 1992 318 liver transplants were performed at our hospital. Of these patients 68 had end-stage cirrhosis due to non-A, non-B, hepatitis, 44 of whom (64.7%) had hepatitis C virus RNA in the serum. Of this subgroup 35 patients (79.5%) were also anti-HCV positive. Postoperatively most recipients remained anti-HCV positive and after 1 year more than 90% had HCV RNA in the serum. About 40% developed a mild, chronic hepatitis and 50% were carriers of HCV without histopathological signs. Two patients suffered from a temporary severe acute hepatitis and one patient had a fulminant liver failure due to reinfection. In general, in liver recipients transplanted for end-stage HCV hepatitis there was a high incidence of reinfection with HCV. The clinical course, however, was less severe than in hepatitis B recurrence.

Carrier State↗
PubMed1994

Selection of small hepatocellular carcinoma improves long-term results of hepatic transplantation for malignancy.

Liver transplantation for advanced hepatocellular carcinoma is often followed by early tumour recurrence and death. At the beginning of the liver transplantation programme at Berlin Virchow we decided to offer liver transplantation only to patients with solitary tumours not exceeding a maximum diameter of 5 cm or to patients with two or three tumour nodes with a maximum diameter of 4 cm. From September 1988 to October 1993 435 liver transplants were performed in 403 patients. Of these, 32 patients (8%) had a histologically confirmed hepatocellular carcinoma (29 males, 3 females, median age 56 years). The overall actuarial survival according to Kaplan-Meier for the whole series of 32 patients with hepatocellular carcinoma was 82%, 78%, and 78% at 1, 2 and 3 years, respectively. Tumour size alone did not seem to be a relevant factor when comparing patients with tumours up to or larger than 3 cm in diameter. Patients with solitary tumours had a better prognosis than patients with multiple tumours. The largest difference was found between patients with stage I-III (UICC) tumours and those with stage IVA tumours: 1-, 2- and 3-year survival rates were 89% throughout in the former group, while the corresponding figures for patients with stage IVA tumours were 63%, 47% and 47%. Efforts should be made to identify stage IVA tumours preoperatively in order to use the precious resource of scarce donor livers in an optimal way.

Actuarial Analysis↗