A retrospective study of pathologically confirmed cases of feline spinal lymphosarcoma (FSL) admitted to the Collages of Veterinary Medicine at the University of Georgia and North Carolina State University from 1 9 7 3 to 1988 was conducted. Two hundred fourteen cases of feline lymphosarcoma were diagnosed histopathologically; involvement of the central nervous system (CNS) was identified in 26 (1 2.1 %). Twenty-three of these tumors involved the spinal cord, and 22 of the 23 were solitary. A predilection for the thoracic and lumbar vertebral canal was noted. Most cats with spinal disease were young, with mean and median ages of 43 and 24 months, respectively; 6 7 cats ymphosarcoma (LSA) is the most common feline neo-

Abstract. Sixty-four canine cutaneous round cell tumors were divided into 25 mast cell tumors, I5 histiocytomas, nine cutaneous lymphosarcornas and 15 transmissible venereal tumors. The final diagnosis was made from cytologic, clinical and histologic findings. Cytologic features were significantly distinctive in mast cell tumor, transmissible venereal tumor, and most cases of histiocytoma and lymphosarcoma to allow a diagnostic opinion. This opinion was supported by subsequent histologic examination. In some instances cytology was considered essential in rendering a diagnostic opinion even though histology was available.In the dog, skin and subcutis are the most common sites for neoplasms, accounting for 67.5% of the neoplasms in one survey [3]. We have found that round cell tumors of the skin make up a significant percentage of these dermal neoplasms. Round cell tumors consist of discrete cells that are round to oval rather than fusiform. Included in this group are mast cell tumor, histiocytoma, lymphosarcoma (including reticulum cell sarcoma) and transmissible venereal tumor. Melanotic tumors occasionally appear as round cell tumors but are not included here. Because the histologic pattern of these neoplasms is often similar, cytologic examination of touch imprints or fine needle aspirations of tumors often can be a valuable adjunct to rendering a definitive diagnosis. The differential diagnosis of round cell tumors by histologic examination without concomitant cytologic characterization may, in some instances, depend more on age of animal, growth rate, location of tumor, number of tumors and lymph node involvement rather than histologic criteria.There have been isolated cytologic descriptions of some of the round cell tumors [2, 4, 5, 8-10]. Our purpose here is to present the cytologic characteristics of canine cutaneous round cell tumors, including those on the external genitalia, and to encourage the use of cytology in the diagnosis of these tumors. 673

Disseminated mycobacteriosis was diagnosed in a 4-year-old, castrated male Domestic Shorthair cat following the observation of one to three retractile, non-staining bacilli in neutrophils and monocytes on a Wright-Leishman-stained blood smear Organisms were bright red following acid-fast staining by Kinyoun's technique. The cat had a history of progressive weight loss, anemia, fever, and sporadic vomiting after eating. In addition to blood smears, mycobacteria also were observed in bone marrow aspirates. During necropsy, multiple small white nodules were observed in the spleen and liver. An enlarged sternal lymph node and ascites also were present. In histologic sections, mycobacteria were observed in granulomas within the lungs, liver, spleen, colon, mesenteric and sternal lymph nodes, omentum, and kidney. Mycobacterium avium complex was isolated from cultures of liver, spleen, lung, and kidney. Occult feline leukemia virus infection, detected by immunofluorescent testing of bone marrow aspirates, may have predisposed this cat to bacterial infection. The serum ELISA test for group-specific feline leukemia virus antigen was negative.

Currently, new product concepts are often evaluated by developing detailed virtual part and assembly models with traditional computer aided design (CAD) tools followed by appropriate analyses (e.g., finite element analysis, computational fluid dynamics, etc.). The creation of these models and analyses are tremendously time consuming. If a number of different conceptual configurations have been determined, it may not be possible to model and analyze each of them due to the complexity of these evaluation processes. Thus, promising concepts might be eliminated based solely on insufficient time and resources for assessment. In addition, the virtual models and analyses performed are usually of much higher detail and accuracy than what is needed for such early assessment. By eliminating the time-consuming complexity of a CAD environment and incorporating qualitative assessment tools, engineers could spend more time evaluating concepts that may have been previously abandoned due to time constraints. To address these issues, the Advanced Systems Design Suite (ASDS), was created. The ASDS incorporates a PC user interface with an immersive virtual reality (VR) environment to ease the creation and assessment of conceptual design prototypes individually or collaboratively in an immersive VR environment. Assessment tools incorporate metamodeling approximations and immersive visualization to evaluate the feasibility of each concept. In this paper, the ASDS system and interface along with specifically designed immersive VR assessment tools such as state saving and dynamic viewpoint creation are presented for conceptual large vehicle design. A test case example of redesigning an airplane is presented to explore the feasibility of the proposed system.

Abstract. Formalin-fixed histologic and acetone-fixed cytologic preparations from 87 surgically removed subcutaneous and soft tissue canine tumors were examined for immunoreactivity to cytokeratin, desmin, and vimentin. The avidin-biotin complex (ABC) technique demonstrated immunoreactivity in both preparations, but the intensity and specificity o~t~ on t he mimary antibody. __ Polyclonal antibodies to cytokeratin were more consislentinimmunoreactivity than were polyclonal desmin or vimentin antibodies. ThFmTnoclonal antibody proved more s a t~~~t o r y f o r~d e~n s t r~t i~~v i m~~~~~~a n the polyclonakmtibody. Greater dilutions of primary antibodies may be used on cytologic preparations than on histologic sections. Evaluation of cytologic preparations may be inconclusive due to background staining, scant cellularity, or poor cytoplasmic preservation.Intermediate filaments have been used as cell typespecific markers for histologic and cytologic evaluation of normal and pathological t i~s u e s .~J~J~,~~ Antibodies that discriminate between different proteins of intermediate filaments can be used to identify tumor cell type and o~i g i n .~J~,~~ Cytokeratin, vimentin, and desmin are present in epithelial, mesenchymal, and muscle cells, respe~tively.~~,~',~~,~' The purposes of this study were to apply avidin-biotin immunoperoxidase staining techniques to demonstrate these proteins of intermediate filaments in tissues and to evaluate the accuracy of these antibody techniques in the diagnosis of routine cytologic preparations. Materials and MethodsEighty-seven neoplastic masses were selected for immunoperoxidase staining in a prospective study from May 1986 to July 1987. Cytologic aspirates or imprints were obtained from surgical tumor biopsy specimens from canine patients. Cytologic preparations were air-dried, fixed in cold acetone for 10 minutes, and stored at -40 C. Surgical biopsy specimens were fixed in 10% neutral-buffered formalin. One cytologic and one histologic preparation were stained with Wright's stain and hematoxylin and eosin (HE), respectively. The remaining unstained slides were used for immunoperoxidase staining by the avidin-biotin-peroxidase complex (ABC) method (Vectastain ABC Kit).15-17 For histologic specimens, paraffin-embedded tissues were sectioned at 5 pm, deparaffinized, rehydrated, and incubated with 0.1% trypsin and 0.1% CaC1, pH 7.8 for 15 minutes at 37 C.7J8 Sections were rinsed in phosphate-buffered saline (PBS) for 10 minutes and placed in 0.3% hydrogen peroxide in methanol for 20 minutes to remove endogenous peroxidase activity. After a 20-minute rinse in PBS, sections were covered with 1% normal goat serum for cytokeratin and desmin staining and 1% rabbit serum for vimentin staining. This was followed by incubation of one slide each with rabbit