Biomedical subjects

D D Davidson

Publications and source records attributed to D D Davidson.

21 records · Page 2Linked to original sources

PubMedDate not supplied

Preclinical in vivo testing of a rotational mechanical thrombolytic device.

PURPOSE: To establish the safety and efficacy of the Arrow Trerotola mechanical percutaneous thrombolytic device (PTD) for restoring patency of thrombosed hemodialysis grafts. MATERIALS AND METHODS: The hindlimb model of dialysis grafts was created in six dogs. Animals had either unilateral (n = 4) or bilateral (n = 2) polytetrafluoroethylene grafts, totaling eight grafts. Grafts were deliberately clotted 48 hours before thrombolysis. Thrombolysis was performed with five different versions of the PTD constructed of stainless steel (n = 12) or nitinol (n = 26) and rotated with use of a hand-held motor drive. After thrombolysis, fistulography was performed. RESULTS: Thirty-eight procedures were performed with the PTD, with 100% success. Thirty-day patency, evaluated in a subset of 15 procedures, was 100%. Complications included a single arterial embolus (2.6%) and eight device breakages (21%, all but two with the stainless steel version); none had any clinical consequences. A final modification of the nitinol device yielded 11 consecutive procedures without further breakage. No residual thrombus occurred in any procedure. Pathologic examination showed no significant injury to the vessels or neointima. CONCLUSION: The PTD is highly effective for mechanical thrombolysis in an animal model of clotted dialysis grafts. Based on this animal model, the device appears safe in its final modified form.

Alloys↗

PubMedDate not supplied

Comparative ultrastructure of needle aspiration biopsy and surgical resection specimens of lung tumors.

Ultrastructural examination affords conclusive evidence for classification of lung tumors. Tissue properly fixed for electron microscopy is not available in many cases, however. Ultrastructural diagnosis of resected specimens obviously follows, rather than directs, the surgical treatment. Fine-needle aspiration (FNA) of lung masses is recommended as a means to obtain lung tumor tissue for electron microscopy. Nevertheless, no comparison has been made between ultrastructural information gained from aspiration specimens and resected specimens. Electron microscopy was performed on transthoracic FNA specimens of 10 lung tumors for which surgical resection was subsequently performed. Glutaraldehyde-fixed specimens from FNA and surgical resection were prepared for electron microscopy according to routine procedures. Fixation of the FNA specimens was equivalent or superior to that of the resected specimens in 9 of the cases. Three of the FNA specimens contained necrotic as well as viable tissue. Features essential for diagnosis such as desmosomes, junctions, neurosecretory granules, intermediate filaments, glycogen, lipid, mucin, and microvilli were identifiable in both FNA and resected specimens. FNA specimens therefore yield a representative sample of the ultrastructural features of lung tumors when adequate cellular material is obtained. Use of a coaxial needle sampling technique with immediate microscopic assessment reduces the likelihood of retrieving only blood or necrotic tissue in the electron microscopy specimens.

Adult↗

PubMedDate not supplied

Aspiration biopsy cytology of smooth muscle tumors. A cytologic approach to the differentiation between leiomyosarcoma and leiomyoma.

From 1970 to 1991, 51 cases of smooth muscle tumors were diagnosed by fine needle aspiration biopsy. All were verified histologically and/or clinically, with no false-positive results. Of the 51 tumors, 41 were leiomyosarcoma and 10 leiomyoma. Among the 41 cases of leiomyosarcoma, 29 were the well-differentiated type; 8, poorly differentiated type; and 4, epithelioid type. Of the 10 cases of leiomyoma, 2 were the epithelioid type. The cytomorphologic features and cytologic patterns of various types of smooth muscle tumors observed in aspirate preparations are presented and compared in order to establish the cytologic criteria for differentiating malignant from benign smooth muscle tumors. Cytomorphologically the various types of smooth muscle tumors were different, and their cytologic features were sufficiently distinctive to distinguish one from the others. It appears possible to differentiate a well-differentiated leiomyosarcoma from a leiomyoma on the basis of cytologic findings observed in aspirate preparations. The recognition of different cytomorphologic features of various types of smooth muscle tumors is important in establishing an accurate cytologic diagnosis, which may be of practical significance to clinical management.

Biopsy, Needle↗