Legal responsibilities of the pathologist.

Pharmaceutical companies exist today in a hostile legal and regulatory environment. The threat of product liability in the pharmaceutical industry has risen to the point where it stifles research and development, especially for contraceptive and psychotropic drugs. Regulatory sanctions against the industry are more likely now than in the past since the Food and Drug Administration (FDA) has placed significant emphasis on regulatory inspection and enforcement. Industrial pathologists play a critical role in defending their company in product liability litigation and from regulatory sanctions. In-house and contract pathologists should be prepared to give expert testimony in court and ensure that an effective document retention policy is implemented. Pathologists should know the limits of the FDA's inspection authority and be aware of the "pitfalls" of the FDA's new Fraud Policy. In addition to keeping abreast of science, industrial pathologists today can best serve the pharmaceutical industry if they maintain an awareness of legal issues that pose a threat to the future success of the industry.

Histopathologic features and post-surgical sequelae of 57 cutaneous neoplasms in ferrets (Mustela putorius furo L.).

The study of the signalment, histomorphologic features, and post-surgical clinical progress of 57 cutaneous neoplasms in 55 domestic ferrets (Mustela putorius furo L.) was based on diagnostic pathologic accessions (1987-1992) from 142 ferrets. Mean age of the group was 4.3 years; 31/54 (57%) were female and 23/54 (43%) were male. Thirty-three (58%) of the cutaneous neoplasms were basal cell tumors. The mean age of ferrets with basal cell tumor was 5.2 years, and 23/33 (70%) were female. Histologically, the basal cell tumors were composed of well-differentiated basaloid epithelial cells with various degrees of squamous and sebaceous differentiation, similar to those seen in basal cell neoplasms of dogs. Nine of the 57 (16%) cutaneous neoplasms were mastocytomas. The mean age of ferrets with mastocytoma was 4.1 years; four were male, four were female, and the sex of one was unrecorded. Histologically, the mastocytomas were composed of well-differentiated mast cells with few eosinophils, similar to cutaneous mastocytomas of domestic cats. The mast cells had a small number of metachromatic cytoplasmic granules, and in six of eight neoplasms the granules had an affinity for conjugated avidin-peroxidase. Six of the cutaneous neoplasms (11%) were fibromas. The mean age of ferrets with fibroma was 2.7 years; 5 (83%) were male. Two cutaneous hemangiomas (4%) were in females, which were 4 and 5 years of age. There was one each hemangiosarcoma, cutaneous polyp, anal gland adenocarcinoma, lymphosarcoma of the prepuce and inguinal lymph node, and adenocarcinoma of the prepuce.

Klossiella equi induced tubular nephrosis and interstitial nephritis in a pony.

Heavy renal infection in a pony with Klosiella equi resulted in moderate diffuse tubular nephrosis and tubular rupture. Multifocal non-suppurative interstitial nephritis was associated with ruptured tubules. Ultrastructural examination of sporoblasts demonstrated both the presence of a bilaminated membrane encasing organisms and nuclear budding. Endogenous corticosteroid production probably led to the development of an immune-compromized state and subsequent extensive parasitic replication.

Immunostimulatory capabilities of highly enriched Langerhans cells in vitro.

Langerhans cells (LC) are epidermal antigen-presenting cells capable of inducing allogenic, antigen-specific, and cytotoxic T cell proliferation. Previous studies have examined the dynamics of LC maintained in vitro in crude epidermal cell (EC) suspensions in which the major cell type is the keratinocyte (KC). To avoid the confounding effects of KC and other immunoregulatory cells on LC dynamics in vitro, highly enriched murine LC (85%) were studied, through 72 h of incubation in vitro, for their ability to present alloantigen (in a primary allogenic proliferation assay) and foreign antigen (in a secondary autologous proliferation assay). The results were compared to similar studies using crude EC suspensions. Freshly prepared LC are very poor stimulators of a primary allogenic proliferation response, with a 12- to 16-fold increase in stimulatory capacity by 72 h using panned-enriched and crude EC suspensions, respectively. Similarly, freshly prepared LC are weak stimulators of a secondary autologous proliferation response, with a 2.5- to 6-fold increase in immunostimulatory capability by 72 h. The overall increased stimulatory effect observed with the crude EC suspensions compared to highly enriched LC is most likely attributed to the effect of KC on T cell proliferation, rather than to a maturation effect of KC on LC during the 72 h of in vitro incubation. Using back-scattered electron imaging, the surface density of MHC-class II molecules (Ia) increased three- to fourfold through culture, which parallels the increase in functional ability. This study demonstrates that LC in either a crude or highly enriched cell suspension mature into potent immunostimulatory cells after incubation in vitro with an increased surface expression of Ia molecules. Keratinocytes are not necessary for LC maturation in vitro, but seem to exert some stimulatory effect by enhancing lymphocyte proliferation in the functional assay system.

Juvenile renal disease in the Doberman Pinscher: ultrastructural changes of the glomerular basement membrane.

Ten cases of juvenile renal disease in Doberman Pinschers were examined by light microscopy and 8 of them additionally by electron microscopy. Two distinct basic ultrastructural lesions of the glomerular basement membrane (GBM) were observed. One is characterized by lamellation of the lamina densa with intramembranous focal areas of lucency containing electron-dense particles, the second by diffuse attenuation of the lamina densa with intramembranous and/or subendothelial deposition of matrix entrapping cross-banded fibres (collagen). Based on similar ultrastructural changes in other hereditary nephropathies in man and dogs, a metabolic or biochemical basis for the structural lesions is suspected.

Purification and identification of murine epidermal dendritic cells: flow cytometry and immunogold labeling.

We report on application of flow cytometric and immunogold labeling techniques to purify and identify two types of murine epidermal dendritic cells: Langerhans cells (LC) and Thy-1-positive dendritic epidermal cells (Thy 1+-dEC). After density centrifugation of epidermal cell (EC) suspensions through Ficoll gradients. IA-positive LC and Thy 1+-dEC are labeled with monoclonal antibodies (fluorescein-conjugated anti-IAd for LC and anti-Thy 1.2-biotin, followed by avidin-phycoerythrin, for Thy 1+-dEC). The fluorescence-activated cell sorter (FACS) is then used to obtain 95-98% pure populations of these dendritic cells with a yield of 2-4 X 10(6) cells and a viability of 80-90%. A post-fixation, pre-embedding immunogold labeling technique using 15 nm and 40 nm colloidal gold particles is employed to identify LC and Thy 1+-dEC, respectively, to confirm the purity of the sorting and to estimate the number of IA antigenic sites per LC. With transmission electron microscopy, ultrastructural morphology of sorted LC is preserved; however, Birbeck granules are markedly diminished compared to the pre-sorted population of LC. In contrast, characteristic dense-core granules are readily visualized in sorted Thy 1+-dEC. Purification of epidermal dendritic cells by flow cytometry may be a useful technique to employ in functional studies of epidermal dendritic cells.

Ultrastructural and phenotypic changes in Langerhans cells induced in vitro by contact allergens.

Ultrastructural changes of murine Langerhans cells (LC) were examined following exposure of crude epidermal cell suspensions to the contact allergens dinitrochlorobenzene, nickel sulphate and lead nitrate at various concentrations and for various incubation times. An immunogold labelling technique was employed to study changes in surface expression of MHC Class II (Ia) molecules. In all cases, activation of LC was evident after as little as 15 min exposure and was characterized by a marked increase in surface expression of Ia molecules, prominent rough endoplasmic reticulum and numerous ribosomes and lysosomes. Degenerative changes in LC were apparent to varying degrees depending on the allergen, its concentration and the time of incubation. Degenerative changes included swollen mitochondria, membrane disruption or rupture, loss of density of the cytoplasm (cytolysis), loss of dendritic processes and decreased expression of Ia molecules. In the case of dinitrochlorobenzene, degenerative changes were present and usually severe at concentrations greater than 10 micrograms/ml, while exposure to nickel sulphate and lead nitrate was associated with only mild degenerative changes. These observations indicate that contact allergens have a variety of direct effects on LC, including activation and degeneration, which are dose- and time-dependent. Since these alterations of LC were observed in the absence of other immunologically active cells, peripolesis cannot be involved in these events.

Microscopic features of canine renal dysplasia.

Forty-five cases of renal dysplasia in dogs are examined. Microscopic lesions of dysplasia include asynchronous differentiation of nephrons, persistent mesenchyme, persistent metanephric ducts, atypical tubular epithelium, and dysontogenic metaplasia. These may be distinguished from secondary lesions including compensatory hypertrophy and hyperplasia of the nephron and a variety of degenerative and inflammatory lesions. Although morphological features of renal dysplasia in dogs differ somewhat from those in man, microscopic criteria used in the diagnosis of human dysplasia may be useful when applied to the dog.

Comparative pathology of canine hereditary nephropathies: an interpretive review.

Hereditary nephropathies in dogs represent multiple complex clinicopathological entities which cause renal failure in juvenile, adolescent, and young adult dogs. To date, nephropathies believed to have a genetic basis have been described in 11 breeds. These disorders represent a variety of developmental, degenerative, and metabolic defects. Many canine hereditary nephropathies are analogous to childhood nephropathies in man. Review of the veterinary literature, comparative pathology, and avenues of future research are discussed.

Neuroepithelioma in a middle-aged dog.

Paresis progressing to paralysis was caused by a neuroepithelioma located at the level of the L1-L2 interspace in a 7 1/2-year-old Golden Retriever. This tumor has never been reported in a dog more than 3 years old. The possibility of a neuroepithelioma should be considered in the differential diagnosis of paresis/paralysis in older dogs.