Biomedical subjects
Publications and source records attributed to R Steffen.
With a careful donor hepatectomy in order to preserve and, if necessary, to reconstruct accessory liver arteries and a microsurgical technique for the arterial anastomosis the rate of arterial complications after liver transplantation can be kept at a low level.
An injury to nonparenchymal cells, characterized by loss of viability of sinusoidal endothelial cells and activation of Kupffer cells, occurs after reperfusion of livers stored for transplantation. Recently, a new solution, Carolina rinse solution, was shown to prevent reperfusion injury to endothelial cells in vitro almost completely and to improve graft survival after orthotopic rat liver transplantation (ORLT) without arterialization. ORLT with arterialization permits longer cold storage of donor livers and more closely models human surgery. Therefore, we evaluated the effects of Carolina rinse solution on graft survival after ORLT with arterialization in syngeneic Lewis rats. Just prior to implantation, donor livers stored in University of Wisconsin (UW) solution were rinsed with 30 ml of Ringer's solution, saline, or Carolina rinse solution at 1 degree-4 degrees C. In livers stored for 15 h and rinsed with Ringer's or saline solution, long-term graft survival was only 8%. Using Carolina rinse solution containing 1 mmol and 200 mumol adenosine per liter, graft survival improved to 40% and 80%, respectively. Graft survival did not improve when using Carolina rinse solution with adenosine omitted or Ringer's solution containing 200 mumol adenosine per liter. Livers were also rinsed with Carolina rinse solution containing 200 mumol adenosine per liter at 28 degrees-30 degrees C rather than at 1 degree-4 degrees C. With warm Carolina rinse solution, survival improved further to 100%, 80%, and 50% after 15, 18, and 21 h of storage. After 18 h of storage, light and electron microscopy demonstrated marked denudation of the sinusoidal lining and activation of Kupffer cells in grafts rinsed with Ringer's solution.(ABSTRACT TRUNCATED AT 250 WORDS)
Explore the source record for details and available documents.
The risk of malaria poses travellers and their advisers with difficult problems as drug resistance spreads worldwide. Protection against infection rests on travellers' knowledge of the risk of malaria, on their avoidance of malaria vectors and on their compliant use of chemoprophylaxis. In this article, Robert Ste f fen and Ronald Behrens explain that one of the priorities for reducing malaria morbidity is to improve travellers' use of personal protection against mosquito bites. They show that none of the drugs, or combinations thereof, provide a 100% efficacy, owing to increasing drug resistance, mainly of Plasmodium falciparum. The commonly used drugs for malaria prophylaxis (mefloquine, doxycycline, chloroquine and proguanil) often cause minor side effects. All, except proguanil, have also been occasionally associated with severe adverse effects. Other drugs (pyrimethaminelsul fadoxine, amodioquine) are not suitable for chemoprophylaxis because of unacceptable adverse reactions. The use of drugs for self therapy is constrained by limitations of toxicity and efficacy, and the added difficulties of defining indications for safe and appropriate use.
A review of the literature shows that 30-35 million travellers from industrialized nations annually visit a developing country where their incidence rate of symptomatic hepatitis A is 3 to 6 per 1000 per month of stay if they remain unprotected. The risk is 20 per 1000 for persons eating and drinking under poor hygienic conditions. Thus hepatitis A is now the most frequent vaccine-preventable disease in such travellers. Antibodies to hepatitis A virus are rarely found in potential travellers in many industrialized countries, except in those born before 1944, in those with a history of jaundice, or in those with a stay > 1 year in a developing country.
1. The marine sponge Verongia aerophoba contains two bioactive secondary metabolites from tyrosine, (+)-aeroplysinin-1 [3',5'-dibromo-1',2'-dihydroxy-4'- methoxycyclohexa-3',5'-dien-1'-yl-methyl-cyanide; abbreviated AP] and dibromoverongia-quinol [3',5'-dibromo-1'-hydroxy- 4'-oxocyclohexa-2',5'-dien-1'-yl-acetamide; abbreviated DV], which display strong cytostatic activity. 2. The concentrations causing 50% inhibition of cell growth are 0.47 microM (AP) and 1.21 microM (DV), resp. 3. Depending on depth regions from which the sponges were collected, differences in occurrence of metabolites were observed. 4. AP and DV were found to be present in sponges collected at a depth of 5-10 m, whereas only DV could be detected in material from deeper regions (20-30 m). 5. AP is present only in the surface layers (both the outer and oscular region) of the sponge, while in the centre of the sponge only DV is detected. 6. Cubes from sponges, collected at a depth of 30 m, were cultivated in seawater in vitro and were found to have the capacity (i) to synthesize AP, and (ii) to release this bioactive material into the medium under defined conditions. Under optimal conditions (light and aeration) 100 g of sponge synthesize and release 13.02 mg of AP during a 10-day incubation period. 7. In the dark and without aeration this synthesis was prevented. 8. These data show that also under in vitro conditions sponges retain the capability of producing bioactive compounds and can be induced to produce even substances which they did not secrete in their natural environment.
The pancreaticojejunostomy after duodenopancreatectomy is the "Achilles' heel" of the procedure. Herein we describe a technique for percutaneous drainage of the efferent limb of the Roux-en-Y loop relieving tension from the anastomosis. Seventy-six Whipple procedures, using this technique, have been done. The operative mortality rate was 1.3 per cent and anastomosis leakage occurred in two instances. In addition, one patient had to be reoperated upon for biliary fistula. Our technique for external Roux-en-Y loop drainage after partial duodenopancreatectomy is safe and efficient and permits rapid diagnosis of anastomotic complications.
269 orthotopic liver transplantations (OLT) were performed in 253 patients at our institution from September 1988 to May 1992. 121 patients had end-stage cirrhosis secondary to viral hepatitis type B, delta, or type non-A non-B and C respectively. Reinfection of the graft by persistent viruses is a potential complication in these cases. Passive immunization with anti-HBs hyperimmunoglobulin (HIg) can prevent clinically relevant reinfection of the graft in patients with hepatitis B virus (HBV) infection and low replication rates. Patients with high replication rates will rarely benefit from OLT. Patients with hepatitis delta virus (HDV) infection usually experience HDV reinfection of the graft with subsequent chronic hepatitis although prophylaxis with anti-HBs-HIg was performed. Treatment with interferon alpha had no apparent effect on the incidence of graft reinfection with HBV in this series, but the replication rate of HDV was reduced. Persistent hepatitis C viruses (HCV) usually infect the graft; this was demonstrated in 17 patients by means of the polymerase chain reaction. HCV infection usually causes a mild form of acute hepatitis with transition to a chronic course. Therefore the significance of persistent viral infection lies in the potential for chronic hepatitis in the transplanted organ rather than in the danger of acute injury of the allograft.
Epidemiological data have rarely been generated during United Nations (UN) missions to Third World countries, even in situations where there is hardly any combat involvement. Continuous surveillance was therefore carried out during the 12-month stay of UN personnel in Namibia in 1989-90. In this population of 7114 persons, mostly young men, the mortality rate was 255 per 100,000; death was mainly due to traffic accidents. Hospitalization was chiefly because of fever of unknown origin or trauma. Repatriation to the country of origin was necessary in 46 patients, frequently for psychiatric reasons including alcoholism. Over this one-year period there were, on average, 2.7 new consultations per person for treatment (mostly for dental problems), and 0.8 per person for prophylactic measures. The extremely high mortality due to traffic accidents indicates a need for prevention. In the selection process for future missions, more emphasis should be given to the psychological and dental health of volunteers. All military contingents and civilian groups should learn about effective preventive measures prior to their arrival, and adhere to them.
Between 1983 and 1985, 257 infertile men were examined for any present varicocele by means of the Doppler sonography, telethermography and palpation. Based on these findings, the spermiogram and the infertility history, high ligation of the spermatic vein was indicated in 89 patients with varicocele and a median duration of infertility of 36 months (6-88 months). Postoperative sperm examinations have shown a significant improvement in sperm count and morphology, but not in motility. The most significant drop was observed in germ cell concentration from 1.68 to 1.06 mio/ml (p less than 0.025 Wilcoxon signed rank sum test). The follow-up examination 6 years after the beginning of the study has shown that only 56 out of the 89 patients underwent surgery, whereas 33 patients refrained from it. Pregnancy rates were 42% (23 out of 55, 1 patient lost to follow-up) in the operated group and 45% (14 out of 31, 2 patients lost to follow-up) in the nonoperated group. The comparison of the two graphs showing pregnancy incidence clearly demonstrates that pregnancies in the nonoperated group occur earlier than in the operated group; it has to be noted, however, that several patients only refrained from being operated on because pregnancy had occurred before surgery was planned. On the one hand, our study confirms other authors' results, i.e. that pregnancy rates in the nonoperated group are relatively high despite present varicocele. On the other hand, the operated group achieved practically the same high pregnancy rate when monitored over a longer period of time.(ABSTRACT TRUNCATED AT 250 WORDS)
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
For successful malaria prophylaxis, future travelers need to be informed about the risks of infection and about systematic measures to be taken against mosquito bites. For visits in areas of high transmission, continuous chemoprophylaxis is recommended, whereas in regions with low transmission a stand-by medication for self-therapy is sufficient. Each of these four measures has some problems which are discussed here in addition to the recently published recommendations by the Swiss Working Group for Medical Advice to Travelers.
A new technique for combined hepatopancreaticoduodenal transplantation in the rat is described. The composite cluster graft consists of an orthotopic arterialized liver graft in anatomical continuity with the pancreaticoduodenal part that is placed heterotopically into the recipient. A separate arterial anastomosis of the liver and a bile duct anastomosis are not necessary, since these structures are left intact in the hepatoduodenal ligament. Bile and exocrine pancreas secretions drain over the duodenal conduit of the graft into the recipient jejunum via an end-to-side anastomosis. This model adds a new transplantation technique to existing microsurgical models.
Reinfection of the graft with hepatitis B virus (HBV) and hepatitis delta virus (HDV) is a potential complication in patients undergoing orthotopic liver transplantation (OLT). Therefore, we added recombinant interferon-alpha (rIFNa) to the standard immunosuppressive regimen in 11 patients who received transplants following liver failure attributed to cirrhosis B (n = 10, with HDV co-infection in four cases) or fulminant hepatitis B (n = 1). Patients were treated with rIFNa for periods ranging from 2 to 3 months between the first and the 13th month after OLT. All patients received immunosuppressive treatment with low-dose corticosteroids, azathioprine and cyclosporine. Anti-HBs hyperimmune globulin was also administered. None of the patients showed evidence of severe allograft rejection. Seven patients suffered HBV reinfection of the graft with histological signs of acute hepatitis in five cases and transition to chronic hepatitis in one patient. Treatment with rIFNa did not prevent or reduce HBV replication. Reinfection of the graft with HDV was demonstrated by PCR in four patients co-infected with HDV. During treatment with rIFNa liver biopsy specimens from three reinfected patients were transiently negative for HDV antigen but not for HDV RNA, and the sera from two patients were transiently negative for HDV RNA. The data indicate that rIFNa can reduce HDV replication in reinfected liver allografts.
This article first examines data bases available to assess the risk of vaccine-preventable diseases (VPD). In the second part, immunization recommendations and practices are briefly evaluated in view of the risk of exposure to VPD and of the efficacy and safety of available vaccines.
To assess the incidence rate and the characteristics of traveler's diarrhea in small children ages 0 to 2 years, children ages 3 to 14 years, and adolescents ages 15 to 20 years a retrospective survey was conducted. Of the pretravel visitors to the Zurich University Vaccination Center, all those ages 0 to 20 years were selected between October, 1987, and May, 1988. They received a questionnaire within 2 weeks after returning home. Of the 446 young travelers who were recruited, 363 (81.3%) could be evaluated. Within 14 days in the tropics or subtropics, traveler's diarrhea occurred in 8 of 20 (40.0%) small children, in 4 of 47 (8.5%) children ages 3 to 6 years, in 10 of 46 (21.7%) children ages 7 to 14 years and in 90 of 250 (36.0%) adolescents (P = 0.0003). In small children the clinical course tended to be severe and prolonged (average duration, 29.5; median, 17.5 days) when compared with other age groups (3 to 5 days). In 40% of all the children the parents reported that they had consistently practiced dietary preventive measures. For self-treatment oral rehydration solutions were used in 5.0% and loperamide in 33.8%. In conclusion adults should be discouraged from taking small children to developing countries unless necessary. Parents should be instructed about how to prevent traveler's diarrhea and about the mainstay of self-therapy in pediatric patients by oral rehydration solutions.