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Biomedical subjects

O E Teebken

Publications and source records attributed to O E Teebken.

At least 19 recordsLinked to original sources
PubMed2006

Severe obstructive calcifications affecting the descending and suprarenal abdominal aorta without coexisting peripheral atherosclerotic disease--coral reef aorta.

The case of a 58-year-old woman with leg claudication due to a very rare form of atherosclerosis affecting the descending thoracic and abdominal aorta--known as coral reef aorta--without involvement of the femoro-distal vessels is reported. The patient was treated with a polyester bifurcation graft from the proximal descending aorta to both common iliac arteries via a left dorsal mini-thoracotomy and a second left retroperitoneal approach. This unusual approach was chosen instead of direct aortic replacement in order to prevent paraplegia. In case of future visceral or left renal malperfusion the diseased artery can be connected to the prosthesis directly or by the use of an additional bypass graft. This would not be the case with a conventional axillo-bifemoral graft.

Anastomosis, Surgical↗
PubMed2005

[Tissue engineering for heart valves and vascular grafts].

Current prosthetic substitutes for heart valves and blood vessels have numerous limitations such as limited durability (biological valves), susceptibility to infection, the necessity of lifelong anticoagulation therapy (prosthetic valves), and reduced patency in small-caliber grafts, for example. Tissue engineering using either polymers or decellularized native allogeneic or xenogenic heart valve/vascular matrices may provide the techniques to develop the ideal heart valve or vascular graft. The matrix scaffold serves as a basis on which seeded cells can organise and develop into the valve or vascular tissue prior to or following implantation. The scaffold is either degraded or metabolised during the formation and organisation of the newly generated matrix, leading to vital living tissue. This paper summarises current research and first clinical developments in the tissue engineering of heart valves and vascular grafts.

Animals↗
PubMed2004

Cryopreserved arterial allografts for in situ reconstruction of infected arterial vessels.

OBJECTIVE: To review our experience of using cryopreserved allografts for in situ reconstruction in the presence of infection involving the aorta, iliac or femoral arteries. DESIGN: Retrospective clinical study. METHODS: From 3/2000 to 8/2003 all patients with mycotic aneurysms or secondary infection following earlier prosthetic replacement were treated with cryopreserved human allografts. Forty-two patients, 39 (93%) with a prosthetic graft infection and 3 (7%) with a mycotic aneurysm of the abdominal aorta were treated. Six (14%) had aorto-enteric fistulas, 5 (12%) had ruptured aneurysms, and 2 also had vertebral destruction. The median follow-up time was 20 months (range 1-42 months). RESULTS: Thirty-day mortality was 14%. Three patients died due to multi-organ failure, two patients died from hypovolaemic shock due to allograft rupture and one from rupture of the native aorta. The overall mortality was 24% (four additional patients). Graft patency was 100% at 30 days and 97% at follow up in the survivors. The mean actuarial survival time was 32 months (95% CI=27-37 months). CONCLUSIONS: Cryopreserved allografts for the in situ reconstruction of infected arteries or grafts have acceptable intermediate results.

Aged↗
PubMed2004

Use of a fibrin preparation in the engineering of a vascular graft model.

OBJECTIVE: Morphological and functional characterization of cocultured endothelial cells (EC) and myofibroblasts (MFB) seeded on a matrix composed of a fibrin preparation mimicking the microenvironment of a vascular wall. METHODS: MFB and EC were isolated from human saphenous veins and expanded separately in vitro. MFB were seeded on a composite matrix consisting of a fibrin preparation (with or without transforming growth factor-beta2) and a polyglactin-mesh to form a 3-dimensional structure, which was consecutively reseeded with EC. Seeded matrices were incubated in a bioreactor. Characterization was done including fluorescence staining, live-/dead-assay and immunohistochemistry. RESULTS: High density cocultures in hierarchical structure mimicking the formation of a vascular wall were obtained with nearly complete coverage of the surface with EC. Distribution of preseeded MFB in a 519+/-27 microm thick layer (day 14) was achieved. Cell viability was shown in fluorescence staining for at least 19 days. In deeper layers, no viable cells could be detected within the fibrin preparation. EC covered the surface, had uniform morphology, and their preserved viability was shown for at least 5 days. No EC-ingrowth was found into the fibrin preparation. Neoformation of the matrix proteins laminin and collagen IV was observed. CONCLUSION: A structured coculture of MFB and EC was obtained mimicking the formation of a vascular wall with preserved viability utilizing a fibrin preparation. Nutrition problems seem to limit the maximal extent of MFB in the matrix.

Blood Vessels↗
PubMed2003

Tissue-engineered bioprosthetic venous valve: a long-term study in sheep.

OBJECTIVE: to develop a graft bearing an immunologically tolerated tissue-engineered venous valve (TE graft) that will be incorporated into a native vessel, and restore normal valve function for the treatment of chronic venous insufficiency. METHODS: twenty-four TE grafts were grown using decellularised allogeneic ovine veins as donor matrix, which was subsequently repopulated with the future recipient's myofibroblasts (MFB) and endothelial cells (EC). TE grafts were implanted into the external jugular vein. Animals were sacrificed at 1, 6, and 12 weeks (n=4, each). Autografts served as controls (1 week, n=4; 6 weeks, n=4). Specimen for histology and immunohistochemistry were taken. RESULTS: the matrix was successfully repopulated with MFB and EC (n=8). Patency on venography in the TE graft-group was44,44, and 34 at 1, 6, and 12 weeks, and44 (44) in autografts at 1 (6) weeks, respectively. Except for 2 TE grafts after 12 weeks, valves were competent (duplex ultrasound). Patent TE grafts were merely distinguishable from autografts with minor inflammatory reactions. Reflux was caused by neo-intima formation related to the basis of the TE graft. CONCLUSION: acellularisation and consecutive in vitro autogeneic re-seeding of valved venous conduits can lead to immunologically acceptable, patent, and competent implants in sheep.

Animals↗
PubMed2001

[Chronic cholecystitis simulating gallbladder tumor with liver abscess. Case report].

We report on a 58 year-old male who presented with nausea, a painful tumor palpable in the upper right epigastrium, moderate fever without leukocytosis. Both ultrasonic scan and subsequent computerized tomography lead to the primary diagnosis of a malignant tumor of the gall bladder infiltrating the liver and inducing an intrahepatic abscess formation in segments 4b and 3. The patient was scheduled for emergency operation, i.e. abscess drainage, cholezystectomy, and hemihepatectomy. However, at operation a purulent chronic cholezystitis was found without involvement of the liver itself. Consequently, a cholezystectomy was necessary and performed. Histological examination of the gall bladder revealed no signs of malignancy. The patient had an uneventful recovery and was discharged on post-operative day seven. This case report shows the difficulties in the differential diagnosis of inflammable processes and malignancies, which affect the gall bladder and adhering structures. A chronic inflammable process can mimic solid tumors. Despite cost-effective diagnostic tools the correct diagnosis was finally found by surgery.

Cholecystectomy↗
PubMed2001

Cell seeded decellularised allogeneic matrix grafts and biodegradable polydioxanone-prostheses compared with arterial autografts in a porcine model.

BACKGROUND: small diameter vascular grafts are limited by their restricted availability, early thrombosis, and requirement for anticoagulants. OBJECTIVE: to evaluate different approaches to biocompatible vascular grafts. METHODS: sixteen allogeneic acellularised arteries seeded with autologous endothelial cells were implanted to replace a segment of the common carotid artery (group I). Other animals received polydioxanone prostheses (group II: inner diameter, i.d. 4 mm, n=18; group III, i.d. 5 mm, n=20) or arterial autografts (group IV, n=8). Graft patency was evaluated by means of ultrasound duplex scanning, angiography and histology. RESULTS: patency was 54% (71%), 17% (0%), 50% (50%), and 100% (100%) in group I, II, III, and IV after 1 week (4 months), respectively. Significant differences (p<0.05) were found for group IV versus all other groups at 1 week, as well as for group IV versus groups II and III, for group II versus III, and group I versus II at 4 months. CONCLUSION: small diameter vascular grafts can be engineered from an acellular allogeneic matrix seeded with autologous cells. Patency is superior to polydioxanone prostheses but inferior to the arterial autograft.

Animals↗
PubMed2000

Differentiated corticosteroid production and regeneration after selective transplantation of cultured and noncultured adrenocortical cells in the adrenalectomized rat.

UNLABELLED: Syngeneic transplantation of adrenocytes was investigated in Lewis rats in regard to differentiated hormone secretion and cortex regeneration after bilateral adrenalectomy as an alternative to steroid substitution. METHODS: Purified cell suspensions of glomerulosa (density 1.061 +/- 0.001 g/ml) and fasciculata (density 1.034 +/- 0.003 g/ml) cells were obtained by density gradient separation and were transplanted under the kidney capsule either immediately or after a 29-day culture period. Animals were killed after transplantation of cultured glomerulosa (CG-Tx) or cultured fasciculata cells (CF-Tx), noncultured glomerulosa cells (G-Tx) or non-cultured fasciculata cells (F-Tx), or both cell types (GF-Tx) for morphological studies after 30, 120, and 360 days. Plasma samples were drawn for measurement of corticosterone and aldosterone as well as 24 hr-urine for sodium and potassium levels at day 3, 30, 120, and 360 after transplantation. RESULTS: In primary culture fasciculata cell number remained stationary although glomerulosa cell number increased to almost 10-fold. Vital cortex cells were demonstrated in each explanted graft by histochemistry but only group G-Tx, CG-Tx, and GF-Tx (purified cell suspensions of zona glomerulosa and fasciculata) showed neocortex-like structures. We found plasma (urine) corticosterone to decrease from preoperatively 256-304 ng/ml (226-239 ng/day) in untreated animals to levels about half as high 3 days after transplantation, increasing to normal values in all study groups 30 days after treatment (data given as range). Plasma aldosterone concentrations, 150-180 pg/ml in untreated rats, decreased to nondetectable levels for 1 week after bilateral adrenalectomy. At day 30 group GF-Tx, G-Tx, and CG-Tx showed comparable aldosterone plasma concentrations (104-122 pg/ml); however, levels in F-Tx and CF-Tx were 19-49 pg/ml, and did not increase significantly within the observation period. CONCLUSIONS: Cells derived from the zona glomerulosa maintain viability, produce both aldosterone and corticosterone, and regenerate a neocortex with cells that histologically resemble both zona glomerulosa and fasciculata cells. They are therefore suitable for adrenocortical transplantation. In contrast, cells derived from the zona fasciculata maintain viability, but do not regenerate zona glomerulosa and do not produce aldosterone. These results suggest that the cell migration model, in which zona glomerulosa cells can acquire the phenotype of zona fasciculata cells as they can migrate centripetally, is more likely the correct explanation of adrenocortical zonation.

Adrenal Cortex↗
PubMed2000

Impact of chronic infection with chlamydia pneumoniae on incidence of cardiac allograft vasculopathy.

Chronic infection with Chlamydia pneumoniae (CP) is associated with development of coronary disease. However, little information exists concerning CP infection and impact on posttransplant cardiac allograft vasculopathy (CAV). A total of 202 patients were investigated 5.5+/-3.1 years after cardiac transplantation (46.5+/-11.0 years; 169 male, 33 female). Assessment of CAV was performed by annual coronary angiograms. Chlamydia serology (IgG/IgA) was performed using micro-immunofluorescence. Statistics comprised analysis of variance and Kaplan-Meier analysis. A total of 152 patients were CAV positive. Elevated titers were present in 45% (IgG) and 72.8% (IgA) of patients. Generally, serostatus was not associated with development of CAV when evaluated over the total postoperative interval. However, after month 14 there was a significant trend toward lower actuarial freedom from CAV in patients with elevated IgA titers. CP seems not to play a significant role in the development of CAV early after heart transplantation but might be a predicting risk factor after the first postoperative year.

Adult↗
PubMed2000

Transplantation of H-2Kb-transgenic adrenocortical cells in the mouse having undergone an adrenalectomy: functional and morphological aspects.

BACKGROUND: A new model of cellular adrenocortical transplantation after bilateral adrenalectomy in the mouse was established. This model was used to study the effects of the expression of the transgenic MHC class I molecule H-2K(b) (Kb) on graft survival and morphologic features, corticosterone secretion, and the possibility of tolerance induction in the recipient. METHOD: A single cell suspension of purified adrenocortical cells was grafted under the kidney capsule of B10.Br (H-2k) mice having adrenalectomies. Syngeneic, fully MHC-mismatched, and MHC class I-incompatible Kb-transgenic mice served as donor strains. To analyze graft function, urinary excretion and serum levels of corticosterone were monitored over 100 days. Tolerance induction in the graft recipients of Kb-transgenic and third party skin grafts was tested on day 50 after adrenocortical transplantation. Histological sections of the adrenocortical grafts were obtained on day 100. RESULTS: Recipients of syngeneic and Kb-transgenic grafts displayed pretransplant corticosterone levels on days 20, 50, and 100 and ACTH-stimulated serum corticosterone levels similar to those of controls on day 100 after adrenocortical transplantation. In contrast, in recipients of fully MHC-mismatched grafts, corticosterone excretion was significantly reduced. In this group, 4 of 7 mice did not survive. Syngeneic skin grafts survived indefinitely in recipients of syngeneic and Kb-transgenic adrenocortical grafts, whereas Kb-transgenic and fully MHC-mismatched skin grafts were acutely rejected. Tissue sections of the adrenocortical grafts revealed vascularized cell conglomerates in syngeneic and Kb-transgenic grafts without infiltrations of mononuclear cells. Furthermore, a differentiation similar to adrenocortical organization was partly found. CONCLUSION: In conclusion, a model of cellular adrenocortical transplantation was established. The results show that syngeneic transplantation resulted in physiological corticosterone levels early after transplantation, whereas fully MHC-incompatible grafts were rejected. Recipients of Kb-transgenic grafts showed unimpaired adrenocortical function, but did not tolerize toward Kb-transgenic skin grafts. Possible mechanisms include a local immunomodulatory effect of glucocorticoids secreted by the graft and a low immunogenicity of the relatively small numbers of transplanted cells.

Adrenal Cortex↗
PubMed2000

Pancreatic metastasis of a pleuropulmonary blastoma in an adult.

Pleuropulmonary blastoma (PPB) is a rare dysontogenetic tumor that usually develops in the first decade of life and has been recognized as a distinct clinico-pathological entity different from the ordinary pulmonary blastoma of adulthood. Since the tumor grows aggressively and tends to metastasize early, physicians have to be aware of late onset of symptoms and uncommon manifestations. We report a case of PPB in a young adult and its recurrence in the pancreas after primary surgical treatment and adjuvant chemotherapy. Keeping in mind the moderate prognosis of PPB in children, accurate assessment and treatment of PPB require a team approach of oncology, radiology and surgery to establish new therapeutic guidelines in the future.

Adolescent↗
PubMed2000

[Harvesting the vena saphena magna for aortocoronary bypass operations--is the subcutaneous suture necessary?].

BACKGROUND: The need for stitching the subcutaneous layers after saphenous vein graft harvest for coronary artery bypass is discussed controversially. METHODS: We conducted a prospective study to determine whether subcutaneous stitches reduce the incidence of hematoma, infection and wound dehiscence after saphenous vein graft harvest in patients undergoing coronary artery bypass grafting. Patients were randomized either to group 1 (n = 100, subcutaneous suture) or group 2 (n = 46, without subcutaneous suture). Leg wounds were examined for hematoma, wound dehiscence, necrosis or secretion preoperatively and on day 2 and 5 after surgery. Furthermore, leg circumferences were measured at distinct areas. RESULTS: There were no significant differences in the incidence of wound complications. Especially, leg circumferences and incidence of hematomas (group 1: 36% versus group 2: 39%) as well as the length of hospital stay (group 1: 6.8 days versus group 2: 6.2 days) did not differ significantly. CONCLUSIONS: The subcutaneous suture following saphenectomy is unnecessary. A deterimental effect of an additional subcutaneous suture could not be demonstrated.

Aged↗
PubMed2000

Tissue engineering of vascular grafts: human cell seeding of decellularised porcine matrix.

OBJECTIVES: To develop a biocompatible and mechanically stable vascular graft combining human cells and a xenogenic acellular matrix. DESIGN/MATERIALS: Decellularised matrix tubes were obtained by enzymatic cell extraction of native porcine aortas. Endothelial cells and myofibroblasts were isolated from human saphenous veins and grown in cell cultures. The inner surface of the tubes was seeded with endothelial cells or myofibroblasts and exposed to pulsatile flow. RESULTS: After cell extraction, the absence of cellular components, as well as the maintenance of matrix integrity, was demonstrated by means of light microscopy and scanning electron microscopy. Furthermore, the porcine matrix was successfully seeded with human endothelial cells, which grew to a monolayer under flow conditions. Stable biomechanical properties were achieved at physiological perfusion pressures in vitro. CONCLUSIONS: Cellular components can be extracted from native porcine blood vessels. Vascular grafts can be generated in vitro of animal acellular matrix and human cells.

Animals↗
PubMed1999

Valve-sparing repair after aortic root dissection following heart transplantation.

We describe the case of a 56-year-old male who presented with a Stanford type A dissection limited to the donor aorta 25 days after orthotopic heart transplantation. Transesophageal echocardiography revealed a newly developed aortic regurgitation grade III and a typical intimal tear 1 cm above the commissures. Surgical therapy included replacement of the ascending aorta with an aortic allograft and implantation of the native aortic valve inside the allograft as a modified David procedure.

Aortic Dissection↗