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Biomedical subjects

A Thiede

Publications and source records attributed to A Thiede.

At least 19 recordsLinked to original sources
PubMed2001

Persistence of stable intragraft cell chimerism in rat liver allografts after drug-induced tolerance.

BACKGROUND: Drug-induced tolerance of rat liver allografts is well documented. We analyzed cellular events during immunosuppressive therapy on day (d) 10 and in the late phase (d 100) after transplantation to assess for characteristics in the intrahepatic leukocyte (IHL) population in the phase of tolerance. METHODS: Lewis rats served as recipients of Dark Agouti rat livers. Temporary immunosuppression with either cyclosporine (CsA) monotherapy (3 mg/kg/d) or triple therapy that consisted of a subtherapeutic CsA dosage (0.25 mg/kg/d) and monoclonal antibodies directed against the interleukin-2 receptor (IL-2R, CD25) and the intercellular adhesion molecule-1 (ICAM-1, CD54) was administered from postoperative d 0 to d 13. Cell migration and cell activation within liver grafts was assessed by standard histology and flow cytometry. IHL apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL). RESULTS: Both CsA monotherapy and triple therapy prolonged liver allograft survival to more than 100 d and led to the induction of donor-specific tolerance. Untreated recipients rejected their allografts within 14 d. In both groups, donor-specific IHLs initially dropped to 18% to 25% on d 10, but they rebounded to as much as 40% on d 100 as a common characteristic of both groups. Within this population, donor-specific T cells were dominant. In both groups, increased numbers of activated (IL-2R+) CD8+ T lymphocytes were present on d 100. No accumulation of apoptotic IHL was observed on d 100. Their proportion was unchanged in the triple therapy group and slightly decreased in the CsA group compared to the syngeneic controls. CONCLUSIONS: The present study reveals that tolerant liver allografts are repopulated by donor-specific T lymphocytes. This phenomenon is independent of the type of applied immunosuppression. The persistence of activated CD8+ T cells in the phase of proven donor-specific tolerance on d 100 indicates that liver tolerance is associated with the state of a permanent intragraft immune activation. It seems that the coexistence of donor cells with infiltrating recipient cells within liver grafts, termed intrahepatic cell chimerism, is characteristic for tolerated liver allografts.

Animals↗
PubMed2001

Orthotopic liver/small bowel transplantation in rats: a microsurgical model inducing tolerance.

Liver cirrhosis in patients with short bowel syndrome is successfully treated in humans by simultaneous liver/small bowel transplantation. However, until now, a clinically relevant experimental rat model for this procedure has not existed. We therefore established a protocol that, for the first time in rats, allows the simultaneous transplantation of arterialized liver and small bowel into an orthotopic position. Short-term immunosuppression induced not only allograft acceptance but tolerance (as demonstrated by indicator heart/skin transplantation). The immunosuppressive dose required to achieve this result was dramatically less than that of protocols for successful small bowel transplantation alone. Immunohistochemistry detected a transient rejection crisis before tolerance. During this crisis, apoptotic recipient-type T lymphocytes, mainly CD8+ cells, accumulated in the liver but not in the small bowel allograft. The initiation of T-cell apoptosis is one possible explanation for the specific immunosuppressive effect of the liver allograft, which also supports the simultaneously transplanted small bowel allograft in our model.

Animals↗
PubMed2001

Rat parathyroid allotransplantation: Influence of MHC antigen expression on graft survival.

MHC antigen expression in parathyroid tissue and its influence on graft survival after allogeneic transplantation were investigated using a heterotopic rat transplantation model. MHC class I and II expression in parathyroid tissue of Lewis (LEW), Dark Agouti (DA), and Wistar-Furth (WF) rats was analysed semi-quantitatively by using immunohistochemistry. MHC class I expression was strong in DA, moderate in WF, and weak in LEW rats parenchyma, whereas MHC class II expression was negative. In the interstitium of all investigated tissue specimens, the proportion of MHC class II-expressing cells was low. Additionally, four groups were transplanted: 1) LEW to LEW, 2) DA to DA, 3) LEW to DA, and 4) WF to LEW. After syngeneic transplantation, graft survival could be documented over the whole observation period. A median graft survival of 20 (+/-2) days was observed after transplantation from LEW to DA, whereas grafts in the group WF to LEW were rejected after 13 (+/-1) days. The number of intra-graft leucocytes expressing MHC class II molecules was the same in all groups, whereas increased levels of MHC class I in parathyroid tissue before transplantation resulted in a more rapid rejection. These results indicate that immunogenicity of rat parathyroid tissue might be determined by the amount of MHC class I expressed in donor parenchymal cells. Further experiments are necessary to validate this observation.

Animals↗
PubMed2001

[Sweat gland carcinoma in the axillary area. A case report and review of the literature].

The sweat gland carcinoma is a rare tumor, representing in approximately 1% of primary skin lesions. In the literature 220 cases of sweat gland carcinomas have been presented over the last three decades. The medium age is 57 years, with an equal male-to-female distribution. Topographically, the tumor is located at the lower limbs (32.9%), the upper extremities (28%), and the head (26%). Involvement of the trunk is rare. Diagnosis can be complicated as the carcinoma is a rare entity, with no correlation of its histologic classification and biologic presentation. This can only implicate the difficulties in treatment.

Adenocarcinoma↗
PubMed2001

Morphologic changes of the anal sphincter musculature during and after temporary stool deviation.

BACKGROUND AND AIMS: Temporary stool deviation, using a stoma, is a well-known surgical principle to protect low colorectal or coloanal anastomoses. The purpose of this study was to evaluate any morphologic changes with regard to the anal sphincter muscles during and after temporary ileostomy. PATIENTS AND METHODS: Forty-four patients with rectal carcinomas were studied prospectively. All patients underwent low anterior resection. Reconstruction was performed using either a coloanal pouch or a straight end-to-end anastomosis. A protective stoma was fashioned in all 44 patients (ileostomy n=41; colostomy n=3). Stoma closure was carried out after a median of 85 days (41-330 days). Using a standard protocol, anal-sphincter thickness [m. puborectalis, external anal sphincter (EAS) and internal anal (IAS) sphincter] was assessed by means of endoanal ultrasonography preoperatively, at the time of stoma closure, and every 3 months thereafter for 1 year. RESULTS: The diameter of the puborectal muscle decreased from a median preoperative value of 6.3 mm to 5.7 mm at the time of stoma closure (P=0.03). After 3 months, 6.2 mm was measured. This value remained stable for the complete follow-up period. Similar results were recorded for the EAS. The IAS thickness remained stable throughout the study period, measuring between 2.1 mm and 2.4 mm. CONCLUSION: Temporary stool deviation does lead to morphologic changes of the anal sphincter. While the smooth muscle remains unchanged, the striated counterpart undergoes atrophic transformation. However, after passage reconstruction, i.e., stoma closure, a rapid regeneration of the voluntary muscles is observed.

Aged↗
PubMed2001

How long should a long-term esophageal motility study be?

It was the aim of this study to analyze whether a shorter measuring period would render the same diagnostic information on esophageal motility as a circadian measuring period in ambulatory esophageal manometry. In an investigation on normal volunteers (n = 10), patients with gastroesophageal reflux disease without esophageal motility disorders (n = 13), and patients with esophageal motility disorders (n = 14), a comparison was performed between a 5-hr and a 24-hr motility study. An analysis was performed on inter- and intraindividual reproducibility of time periods, prandial phases, and motility sequences (Wilcoxon and Spearman test). There was no significant difference between the two analyzed measuring periods in all three groups with regard to the diagnostic information on esophageal motility in 44 of 45 comparisons for intraindividual variability. A measuring period restricted to 5 hr offers the same diagnostic information on esophageal peristaltic activity as a 24-hr motility study.

Adult↗
PubMed2001

Prospective study on plasma clotting parameters in diabetic children--no evidence for specific changes in coagulation system.

In a prospective study, clotting parameters of 37 children and adolescents with insulin-dependent diabetes mellitus (type 1 diabetes) were compared with those of a healthy control group. In a longitudinal follow-up over two years we found no statistical difference for most of the coagulation parameters investigated, including single factor analysis and coagulation inhibitors. The duration of type 1 diabetes was of no influence on these parameters. The only difference we found between patients and healthy controls was an elevation of PAI-1 in diabetics: median for PAI-1: 2.12 IU/ml in diabetics (range 0.50-8.40 IU/ml) and 0.84 IU/ml in normal controls (range 0.50-1.78 IU/ml). This difference was of statistic significance (p < 0.002) and also found in newly diagnosed patients. During observation time, none of our patients developed thrombosis or signs of vascular disease. In conclusion, we could not confirm the development of a hyper-coagulable state in pediatric diabetics, as it is described for adults with type 1 diabetes mellitus.

Adolescent↗
PubMed2001

[Conceptual and practical aspects of creating an internet presentation of a surgical department].

Until recently an internet presentation of a surgical department could rarely be found on the World Wide Web (WWW). Today an increasing number of departments provide a Web site, but often contents and graphics can still be improved. For more than 4 years the Department of Surgery at the University Hospital of Würzburg has maintained an internet presentation (www.chirurgie.uni-wuerzburg.de). Contents and technical features have been continuously updated. In order to provide a powerful Web site, contents were structured for the 3 target groups: visitors, that are patients including their relatives (consultation hours, directions, maps of campus and wards), physicians (main points in diagnostics and therapy, research, publications, further education, job offers) and medical students (teaching schedules, courses, learning materials). Concerning the technical aspects of the Web site, emphasis was put on a distinct layout and clear design. Therefore, text was arranged in tables or lists and a limited number of standard fonts was used. Graphics were compressed to a minimum file size. To allow effortless navigation for the visitor two roll-over menu banners, a sitemap, a search tool and easy-to-follow symbols were implemented. The internet is an important source of information, and used correctly, the WWW is very useful for the presentation and communication of a surgical department.

Family↗
PubMed2001

[Restoration of blood circulation in reperfusion of ischemic tissues].

In experiment there were studied changes of the tissue blood circulation and microcirculation during postischemic reperfusion of skeletal muscles with various density of capillaries. It was established that reactive hyperemia, caused mainly by enhancement of extracapillary tissue blood flow. While persistence of durable arterial hypertension the capillaries quantity and potential volume of microcirculatory bed are reducing, negatively influencing the blood circulation restoration process during postischemic reperfusion. In chronic ischemia the potential volume of microcirculation is increasing, securing complete restoration of blood circulation in postischemic reperfusion.

Animals↗
PubMed2000

Tolerance of rat liver allografts induced by short-term selective immunosuppression combining monoclonal antibodies directed against CD25 and CD54 with subtherapeutic cyclosporine.

BACKGROUND: Our purpose was to develop and evaluate protocols for selective immunosuppression after liver transplantation using the monoclonal antibodies (mAbs) NDS-61, directed against the interleukin-2 receptor (CD25), and 1A29, directed against the intercellular adhesion molecule-1 (CD54), in combination with subtherapeutic cyclosporine (CsA). METHODS: Orthotopic rat liver transplantation (ORLT) was performed in a DA-to-LEW strain combination. Immunosuppression was administered from day 0 to +13. Functional parameters such as survival time, body weight, and serum bilirubin levels were measured and the liver grafts were evaluated histologically. RESULTS: A stepwise tapering of CsA from 3 to 0.25 mg/kg/day reduced the long-term survival rate. All animals died at a CsA dosage of 0.25 mg/kg/day, which was therefore defined as subtherapeutic. Monotherapy with the anti-CD25 mAb was performed at dosages of 600 and 1800 microg/kg/day. The lower mAb dosage resulted in a long-term survival rate of 12% and was defined as subtherapeutic. The combination therapy of CsA (0.25 mg/kg/day) and anti-CD25 mAb (600 microg/kg/day) produced a synergistic effect and led to a long-term survival rate of 84%. This survival rate was significantly higher than those after either CsA (P<0.005) or anti-CD25 mAb (P<0.001) monotherapy. Both dosages (10 and 30 microg/kg/day) of anti-CD54 mAb monotherapy as well as anti-CD54 mAb combined with a subtherapeutic dosage of CsA were ineffective in preventing acute allograft rejection. The addition of anti-CD54 mAb (30 microg/kg/day) to combined CsA plus anti-CD25 mAb therapy (triple therapy), however, increased the long-term survival rate to 100%. In the triple therapy group there was no rejection process in the liver allografts at any time, and donor-specific tolerance could be shown by donor-specific and third-party heterotopic heart transplantation. CONCLUSIONS: The synergistic action of subtherapeutic CsA plus anti-CD25 mAb NDS-60 could be demonstrated, whereas anti-CD54 mAb only had a positive effect in a triple therapy group. Triple therapy prevented both acute and chronic rejection and induced donor-specific tolerance.

Animals↗
PubMed2000

[Aorto-mesenteric artery compression syndrome].

INTRODUCTION: The aim of this paper was to describe a rare gastrointestinal motility disorder caused by vascular compression of the duodenum. PATIENTS: The authors present two patients with vomiting and severe weight loss. Diagnostic evaluation revealed superior mesenteric artery syndrome. METHODS: After frustrane treatment with i.v. infusions, surgical intervention with laterolateral duodenojejunostomy or Roux-en-y reconstruction for restoration of the intestinal passage was performed. RESULTS: Following initial recovery, the first patient showed permanent anorexia. Psychosocial evaluation revealed a severe pathological mother-child relationship. Intensive psychological treatment finally achieved definite weight gain and complete recovery in this patient. The second case subsequently gained weight without psychological evaluation. CONCLUSION: The authors review the literature, pointing out the anatomy of the duodenojejunal angle, the etiology, and the predisposing factors, as well as diagnostic and therapeutic strategies.

Adolescent↗
PubMed2000

Donor-derived alloantigen-presenting cells persist in the liver allograft during tolerance induction.

The predictive value of chimerism was evaluated in three different transplantation models in the rat without immunosuppression: small bowel- (SBTx), liver- (LTx), and liver/small bowel transplantation (LSBTx) were performed in the Brown Norway (BN)-to-Lewis-(LEW) strain combination. Immunohistochemistry and flow cytometry were used to identify donor cells in the recipient's spleen. Their number did not change significantly during transient rejection or tolerance after LTx and LSBTx. However, the amount of donor-derived nonparenchymal cells within the liver allograft including antigen-presenting cells (APCs), such as dendritic and Kupffer cells, clearly mirrored the recipient's immune status: as expected, their number decreased during rejection, but recovered considerably during and after tolerance induction. We conclude that donor cells in the periphery of the recipient correlate with the presence of the allograft, but do not seem to influence graft acceptance actively. However, the kinetics of the detected donor APC population in the liver suggests their important role in modifying the recipient's immune response towards tolerance.

Animals↗
PubMed2000

"Tolerogenic effect" of the liver for a small bowel allograft.

A newly developed liver/small bowel transplantation model (LSBTx) was used to investigate the tolerogenic effect of a liver allograft toward a simultaneously transplanted small bowel. Small bowel transplantation (SBTx) under high-dose immunosuppression was compared to LSBTx with a lower FK506 dosage. Syngeneic Lewis [(LEW) to LEW] and two fully allogeneic rat strain combinations (Brown Norway-to-LEW and Dark Agouti-to-LEW) were used. Clinical course and histological findings after SBTx demonstrated a chronic rejection of the small bowel allograft within 100 days. However, after LSBTx long-term acceptance (> 150 days) was achieved after a transient rejection crisis, although initial immunosuppression was significantly lower. Furthermore, indicator heart transplantations demonstrated the induction of donor-specific tolerance in both allogeneic strain combinations. In contrast to other LSBTx rat models, these results reflect observations after human LSBTx, in which the rate of acute and chronic rejection is also significantly lower than after human SBTx.

Acute Disease↗
PubMed2000

Analysis of cellular events in hepatic allografts: donor progenitors induce intragraft chimerism.

Long-term graft acceptance and tolerance induction after allogeneic rat liver transplantation are well described. However, the underlying mechanisms remain unclear. In this study we investigated the cellular events within the liver graft during initial immunosuppression and long-term acceptance. Orthotopic liver transplantation was performed in the Dark Agouti (DA)-to-Lewis (LEW) and LEW-to-DA rat strain combination. In order to achieve long-term acceptance, LEW recipients of DA livers were treated with two different short-term therapies. Non-parenchymal cells (NPC) were isolated from liver allografts on days + 10 and + 100 after transplantation and donor-specific leukocytes were immunophenotyped by flow cytometry. Both the monotherapy and triple therapy prolonged graft survival (> 100 days). Liver allografts from LEW donors into DA recipients were spontaneously accepted across a complete MHC mismatch without immunosuppression. Liver allograft rejection was induced by infiltrating alloreactive immunocompetent cells. But the intensities of cell infiltration in the early and late phases after transplantation did not correlate with eventual outcome. Donor-specific NPC decreased to 18-25% on day + 10 in both therapeutic groups, but had rebounded to up to 40% by day + 100. Recurrence of donor-specific cells was caused almost exclusively by rising T cell counts. The persistence of dendritic cells in the late phase after transplantation could be clearly demonstrated. Repopulation by donor-specific T lymphocytes was observed in long-term accepted liver grafts. This recurrence may be based on the differentiation of liver-derived progenitor cells. The persistent coexistence of donor and recipient cells within the liver allograft (intrahepatic chimerism) appears to be characteristic and may be important for long-term acceptance.

Animals↗
PubMed2000

Long-term small bowel allograft function induced by short-term FK 506 application is associated with split tolerance.

Functional long-term allograft survival after experimental small bowel transplantation (SBT) is limited by chronic rejection. Initial application of high-dose FK 506 has been shown to induce stable long-term graft function. In order to examine whether this long-term function is associated with donor-specific tolerance, we analyzed the functional status of recipient T cells in vivo and in vitro. One-step orthotopic SBT was performed in the allogeneic Brown Norway (BN)-to-Lewis rat strain combination. FK 506 was given daily at a dose of 2 mg/kg from days 0-5 in the rejection model and from days 0-9 in the long-term functional model. Mean survival time in the rejection model was 98 +/- 2.8 days. Histological examination of these small bowel allografts disclosed signs of chronic rejection. In contrast, all animals of the long-term functional model survived long term (> 250 days) without clinical signs of chronic rejection. The latter model, furthermore, produced evidence of donor-specific tolerance. Whereas heterotopic Dark Agouti (DA) hearts were rejected regularly within 7 days, BN hearts survived indefinitely (> 70 days). In vitro, mixed leukocyte reactivity of CD4+ T cells was similarly strong against donor (BN) antigens as against third-party (DA) antigens. The split tolerance revealed by our in vivo and in vitro results enabled acceptance of both the small bowel allograft without signs of chronic rejection and of donor-specific heart allografts.

Animals↗
PubMed2000

Comparison of anastomotic microcirculation in coloanal J-pouches versus straight and side-to-end coloanal reconstruction: an experimental study in the pig.

Several studies have shown a lower rate of anastomotic leakages in patients with coloanal J-pouch reconstruction than in those with straight coloanal anastomosis following anterior resection of the rectum. This study investigated whether this difference is due to a better anastomotic microcirculation. Thirty-two healthy, adult Göttinger mini-pigs underwent anterior rectal resection. They were subsequently randomized to following four groups (eight pigs per group): straight end-to-end, side-to-end, small pouch (4 cm), and large pouch (8 cm) coloanal anastomosis. Bowel perfusion was measured before and after vessel ligature at predefined locations using laser Doppler flowmetry. After completion of the anastomosis microcirculation was investigated 1 cm above, below, and directly at the anastomotic site. Following vessel ligature there was a 25% drop in blood flow. After completion of the anastomosis there was a further decrease of 25% in the distal segment, while no changes were observed above the anastomosis. There were no statistical differences either before or after completion of the anastomosis between the various groups. It is concluded that anastomotic blood flow does not depend on the type of coloanal reconstruction in healthy pigs.

Anastomosis, Surgical↗