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Biomedical subjects

P Barth

Publications and source records attributed to P Barth.

136 records · Page 8Linked to original sources
PubMedDate not supplied

Postmortem evaluation of four randomly selected automated biopsy devices for transthoracic lung biopsy.

PURPOSE: To evaluate four automated devices to achieve transthoracic lung biopsy. METHODS: Transthoracic lung biopsy specimens were obtained randomly from 21 human cadavers with unsuspicious lungs using Biopty (18- and 20-gauge), BIP (18 and 20-gauge), ASAP (18 gauge), and Autovac (18- and 20-gauge) devices. A total of 63 biopsies were carried out with each device and each needle diameter. The same devices and needles were then used randomly for biopsy of peripheral lung metastases. Specimens obtained during both parts of the study were analyzed for the area of tissue on the histologic section, adequacy of tissue for diagnosis, tissue preservation, and crush artifact. The examining pathologist was kept unaware of which procedure was used to obtain the specimens and the cadavers' clinical history. RESULTS: The Biopty 18-gauge device performed statistically better than any other of the evaluated systems for biopsy of normal lung parenchyma (p < 0.05). For biopsy of lung metastases, the differences between the devices and needle diameters were less, although the Biopty 18-gauge device performed better than the Autovac 18-gauge, BIP 18-gauge, and all 20-gauge devices for the area of tissue on the histologic section (p < 0.05). The results of the full-cut Autovac biopsy system were remarkable because of the large number of biopsies during which no tissue was obtained. CONCLUSION: Automated biopsy devices can obtain high quality lung specimens sufficient for definite histopathologic diagnosis. However, additional clinical studies on the use of automated biopsy devices for lung biopsy are mandatory.

Automation↗
PubMedDate not supplied

Are covered stents really effective at closing esophagotracheal fistulas? Results of an animal study.

PURPOSE: To determine whether covered self-expanding metal stents successfully exclude experimentally created esophagotracheal fistulas. METHODS: Esophagotracheal fistulas were surgically created in the upper third of the esophagus in 12 minipigs and immediately sealed by implantation of a covered self-expanding metal stent (20 mm expanded diameter) in the esophagus. Before the animals were killed, after 3, 7, 14, 28, 30, and 36 days, the position of the stent and the sealing of the fistula were monitored fluoroscopically. The esophagus, trachea, and both lungs were examined histologically. RESULTS: Creation of an esophagotracheal fistula was successful in all cases. All fistulas were widely patent at autopsy. The technical success rate for stent deployment and initial sealing of the fistula was 100%. During follow-up, five stents migrated distally, but none into the stomach. Therefore, the fistula was no longer excluded in five animals. In seven animals the stent sealed the fistula until the death of the animal. Tracheal narrowing necessitated additional tracheal stenting in three animals. Two minipigs died due to aspiration of food. Histologic examination showed signs of aspiration in all animals with stents in place for longer than 2 weeks. CONCLUSION: This experimental animal study revealed worse results for sealing of esophagotracheal fistulas with covered self-expanding metal stents than have been reported for the clinical use of these devices.

Animals↗
PubMedDate not supplied

Subchondral magnetic resonance imaging changes in early osteoarthrosis associated with tibial osteonecrosis.

SUMMARY: The authors report on 41 patients with acute or subacute knee pain and early or midstage degenerative arthrosis with osteonecrotic lesions in the subchondral and metaphyseal region of the medial proximal tibia. Each lesion was identified only on magnetic resonance images (MRI). These MRI changes are classified and the clinical course is defined during a follow-up period averaging 4.5 years. Radiographically, 22 patients had minimal degenerative changes; 12 had moderate arthritis; and 7 were normal. With MRI, 3 distinct types of lesions were identified. Type A lesions had localized areas of decreased signal in the subchondral area. Type B lesions had diffuse signal changes with extension into the metaphysis. Type C lesions had metaphyseal involvement as well as a marginated serpentine subchondral rim usually associated with advanced osteonecrosis. There were 9 type A lesions, 23 type B, and 9 type C. At the end of 1 year, 33 patients (80%) had no or mild symptoms, and 8 (20%) had persistent moderate pain. At 4.5-year follow-up, most patients had symptoms consistent with progressive osteoarthrosis, 12 patients had severe symptoms (29%), 17 (41%) had mild or moderate symptoms, and only 12 (29%) were asymptomatic or had minimal symptoms. The type of MRI change seen initially was predictive of prognosis. Only 6 (19%) of the 32 patients with type A or B findings had severe symptoms at last follow-up. Six (66%) of the 9 patients with a type C MRI lesion had severe symptoms or had an operation by last follow-up. Twelve patients had follow-up MRI at a mean 15 months (range, 12 to 18 months) after the initial evaluation. The type A and B changes were either absent or significantly reduced. The type C subchondral marginated rim changes remained but metaphyseal involvement was reduced. There appears to be a spectrum of tibial subchondral MRI changes associated with sudden onset of medial knee pain in patients with early osteoarthritis of the knee. These changes may be indicative of osteonecrosis. The initial MRI classification is useful in predicting prognosis. Recognition of this problem may avoid unnecessary intra-articular surgery.

Aged↗
PubMedDate not supplied

First successful xenotransplantation of microencapsulated human parathyroid tissue in experimental hypoparathyroidism: long-term function without immunosuppression.

Owing to the complexity of the parathyroid hormone's metabolic interactions, clinical hypoparathyroidism is one of the most difficult of all endocrine disorders to treat. Therefore, causative treatment of this disorder by transplantation of parathyroid glands is highly desirable. We have recently documented the long-term in vivo function of iso- and allotransplanted rat parathyroid tissue without systemic immunosuppression in an animal model. In view of the potential clinical use of this method, human parathyroid tissue has been microencapsulated and transplanted over the highest immunological barrier. In a controlled, long-term animal study in the parathyroidectomized rat, the effect of microencapsulation on xenotransplanted human parathyroid tissue was evaluated over 30 weeks (native and microencapsulated parathyroid tissue = 40 rats respectively). Functionally, human parathyroid tissue was able to replace that of the rat. All animals that had received microencapsulated parathyroid tissue were normocalcemic for 16 weeks; 27/40 at the end of the study. In contrast, serum calcium concentrations dropped to post-parathyroidectomy levels within 4 weeks in those animals that had received native tissue only. Histologic evaluation of the explanted, functionally successful xenografts showed vital parathyroid tissue inside intact microcapsules surrounded by a small rim of fibroblasts. Avital fibrotic remnants were demonstrated in animals with non-encapsulated parathyroid tissue. Thus, we have established the feasibility of microencapsulation of human parathyroid tissue, preserving its viability over long periods in vivo even if xenotransplanted. In combination with an improved tissue culture method, transplantation of human parathyroid tissue and maintenance of its physiological function is reproducibly achieved without postoperative systemic immunosuppression over the highest transplantation barrier. This may be a crucial step towards the first clinical application of this method.

Animals↗
PubMedDate not supplied

Local tolerance to spider silks and protein polymers in vivo.

Spider silks were implanted subcutaneously in pigs for a study of the tolerance against this material. Four types of spider silks of high purity and cleanliness were implanted: (i) major ampullate dragline silk reeled from the golden silk spider Nephila clavipes, (ii) native (unsterilised) silk reeled from a Brachypelma spider, (iii) native silk taken from this spider's web and (iv) its web silk thermally treated at 80 degrees C. For comparison we used fibrous silk analogue protein polymers and four already marketed wound dressings (polyurethane film, collagen dressings, gauze pads). All materials were applied epicutaneously to split skin wounds. The implants were examined macroscopically as well as by light microscopy. Superficially, all sites healed rapidly. There were marked inflammatory reactions in all sites with lympho-plasmacellular infiltrations, evidence of phagocytosis and granuloma formation as indicated by the appearance of giant cells. However there was a marked absence of epitheloid cells indicating that the observed reaction was a foreign body granuloma. Furthermore, the histopathological images recorded after 14 days revealed no marked differences between the dressings. Polyurethane films, however, seemed to be superior with respect to the duration of the wound healing process.

Animals↗
PubMedDate not supplied

Influence of matrix metalloproteinase 9 (MMP-9) on the metastatic behavior of oropharyngeal cancer.

BACKGROUND: The role of the single matrix metalloproteinases (MMPs) in the metastatic process of squamous cell carcinomas (SCC) is still obscure. MATERIALS AND METHODS: The MMP-9 expression was described immunohistochemically in 105 patients (40-79 years of age, mean: 57.84 years; 84 male, 21 female) suffering from orophatyngeal cancer (22x TI, 31x T2, 24x T3, 28x T4) with different neck stages (41x N0, 6x N1, 54x N2, 4x N3 neck). RESULTS: A significant correlation between MMP-9 expression and T stage (p < 0.05), N stage (r = 0.55, p < 0.01) and UICC stage (r = 0.55, p < 0.01) was revealed. Most remarkable was the high MMP-9 expression with simultaneously high UICC stages. CONCLUSION: The results give further indication that MMP-9 plays a role in the metastatic behavior of oropharyngeal SCC. It will be a project for the near future to create a standardized evaluation score of immuno-histological stainings to allow valid comparison of the results and published data.

Adult↗