Recommended guidelines for submission, trimming, margin evaluation, and reporting of tumor biopsy specimens in veterinary surgical pathology.

Neoplastic diseases are typically diagnosed by biopsy and histopathological evaluation. The pathology report is key in determining prognosis, therapeutic decisions, and overall case management and therefore requires diagnostic accuracy, completeness, and clarity. Successful management relies on collaboration between clinical veterinarians, oncologists, and pathologists. To date there has been no standardized approach or guideline for the submission, trimming, margin evaluation, or reporting of neoplastic biopsy specimens in veterinary medicine. To address this issue, a committee consisting of veterinary pathologists and oncologists was established under the auspices of the American College of Veterinary Pathologists Oncology Committee. These consensus guidelines were subsequently reviewed and endorsed by a large international group of veterinary pathologists. These recommended guidelines are not mandated but rather exist to help clinicians and veterinary pathologists optimally handle neoplastic biopsy samples. Many of these guidelines represent the collective experience of the committee members and consensus group when assessing neoplastic lesions from veterinary patients but have not met the rigors of definitive scientific study and investigation. These questions of technique, analysis, and evaluation should be put through formal scrutiny in rigorous clinical studies in the near future so that more definitive guidelines can be derived.

Heritable T-cell malignancy models established in a zebrafish phenotypic screen.

T-cell neoplasias are common in pediatric oncology, and include acute lymphoblastic leukemia (T-ALL) and lymphoblastic lymphoma (T-LBL). These cancers have worse prognoses than their B-cell counterparts, and their treatments carry significant morbidity. Although many pediatric malignancies have characteristic translocations, most T-lymphocyte-derived diseases lack cytogenetic hallmarks. Lacking these informative lesions, insight into their molecular pathogenesis is less complete. Although dysregulation of the NOTCH1 pathway occurs in a substantial fraction of cases, many other genetic lesions of T-cell malignancy have not yet been determined. To address this deficiency, we pioneered a phenotype-driven forward-genetic screen in zebrafish (Danio rerio). Using transgenic fish with T-lymphocyte-specific expression of enhanced green fluorescent protein (EGFP), we performed chemical mutagenesis, screened animals for GFP(+) tumors, and identified multiple lines with a heritable predisposition to T-cell malignancy. In each line, the patterns of infiltration and morphological appearance resembled human T-ALL and T-LBL. T-cell receptor analyses confirmed their clonality. Malignancies were transplantable and contained leukemia-initiating cells, like their human correlates. In summary, we have identified multiple zebrafish mutants that recapitulate human T-cell neoplasia and show heritable transmission. These vertebrate models provide new genetic platforms for the study of these important human cancers.

A homolog of voltage-gated Ca(2+) channels stimulated by depletion of secretory Ca(2+) in yeast.

In animal cells, capacitative calcium entry (CCE) mechanisms become activated specifically in response to depletion of calcium ions (Ca(2+)) from secretory organelles. CCE serves to replenish those organelles and to enhance signaling pathways that respond to elevated free Ca(2+) concentrations in the cytoplasm. The mechanism of CCE regulation is not understood because few of its essential components have been identified. We show here for the first time that the budding yeast Saccharomyces cerevisiae employs a CCE-like mechanism to refill Ca(2+) stores within the secretory pathway. Mutants lacking Pmr1p, a conserved Ca(2+) pump in the secretory pathway, exhibit higher rates of Ca(2+) influx relative to wild-type cells due to the stimulation of a high-affinity Ca(2+) uptake system. Stimulation of this Ca(2+) uptake system was blocked in pmr1 mutants by expression of mammalian SERCA pumps. The high-affinity Ca(2+) uptake system was also stimulated in wild-type cells overexpressing vacuolar Ca(2+) transporters that competed with Pmr1p for substrate. A screen for yeast mutants specifically defective in the high-affinity Ca(2+) uptake system revealed two genes, CCH1 and MID1, previously implicated in Ca(2+) influx in response to mating pheromones. Cch1p and Mid1p were localized to the plasma membrane, coimmunoprecipitated from solubilized membranes, and shown to function together within a single pathway that ensures that adequate levels of Ca(2+) are supplied to Pmr1p to sustain secretion and growth. Expression of Cch1p and Mid1p was not affected in pmr1 mutants. The evidence supports the hypothesis that yeast maintains a homeostatic mechanism related to CCE in mammalian cells. The homology between Cch1p and the catalytic subunit of voltage-gated Ca(2+) channels raises the possibility that in some circumstances CCE in animal cells may involve homologs of Cch1p and a conserved regulatory mechanism.

The role of free radical-mediated processes in oxygen-related damage in cultured murine myocardial cells.

A new approach to quantifying myocyte cell death utilizing fluorescence-activated sorting of antimyosin antibody-labeled cells was used to study the effects of oxygen-generated free radicals on cell survival. Uptake of antimyosin, reflecting sarcolemmal damage, increased under conditions which promoted elevated free radical formation and decreased in the presence of increased levels of free radical-scavenging agents. Superoxide dismutase decreased antimyosin uptake at pH 6.7 and 7.5. Mannitol decreased antimyosin uptake at pH 6.5 and 6.7 but not at pH 7.5, and dimethyl sulfoxide decreased antimyosin uptake at pH 6.4 but not at pH 7.5. These data suggest that a greater portion of hydroxyl radicals are produced at higher concentrations of hydrogen ion. Mannitol, a scavenger of hydroxyl radicals, was effective in reducing antimyosin uptake at pH 7.5 in the presence of ferrous sulfate, but had no effect on antimyosin uptake in the absence of ferrous sulfate, suggesting possible iron-mediated catalysis of hydroxyl radical formation. The data suggest that oxygen-derived free radicals can cause significant loss of membrane integrity in cultured myocytes, that the species of radical formed is dependent both on pH and the concentration of iron salts, and that this injury is, at least in part, preventable by the administration of exogenous radical scavenging agents.

Technetium-99m labeling of antibodies to cardiac myosin Fab and to human fibrinogen.

We have developed a method of labeling biologically active labile macromolecules, such as human fibrinogen (HF) and anticardiac-myosin Fab (AM-Fab), with Tc-99m at neutral pH. This method uses dithionite reduction of pertechnetate and subsequent labeling, to test the method with acid-labile macromolecules. Complexes of diethylene triamine pentaacetic acid with macromolecules such as human fibrinogen (D-HF) and anticardiac-myosin Fab (D-AM-Fab) were labeled and utilized in in vitro and in vivo studies. In biodistribution studies, the Tc-99m D-HF had a two-component blood clearance (half-times 1 hr and 15 hr) and was 80--88% coagulable. The Tc-99m AM-Fab retained its immunoreactivity as tested by affinity chromatography; also during in vivo localization in experimental myocardial infarction. This labeling technique provides an easy and efficient approach to the Tc-99m labeling of other biologically active and acid-labile macromolecules.

Role of sulfate conjugation in estrogen metabolism and activity.

There has been an increasing interest in the sulfate conjugates of estrogens as important metabolites in steroid hormone homeostasis and activity. In women estrogen sulfates have been known as major components of plasma originating from ovarian secretion and hepatic metabolism. However, only recently has the capacity to sulfurylate estrogens been demonstrated in estrogen target tissues. Porcine uterus estrogen sulfotransferase appears only after the first complete estrous cycle. Following puberty, gilt uterine sulfurylation of estrogens is extremely active during diestrus, whereas estrogen sulfotransferase is not present during estrus. This cycling of estrogen sulfurylation in porcine and human uteri can be related directly to plasma progesterone levels. Rodent and human mammary tumors are also highly active in both steroid alcohol and estrogen sulfotransferases. Unlike uterine sulfotransferases, these enzymes are apparently stimulated by factors that appear following ovariectomy. The function of estrogen sulfurylation by target tissues remains obscure. However, recent investigations have indicated that the cyclic variation in endometrial estrogen sulfurylation may control the availability of 17 beta-estradiol to the cytoplasmic receptor. This premise is supported by the continued high estrogen sulfurylation activity and low nuclear receptor levels during implantation in fertilized gilts and sows. Utilizing purified bovine adrenal sulfotransferase, the substrate and inhibitor requirements were determined for this enzymes. It was also possible to design a specific inhibitor that will block estrogen sulfurylation without interfering with the receptor binding and nuclear migration of physiological levels of 17 beta-estradiol. This inhibitor, 3-methoxy-4-nitroestrone, will help in establishing the role of uterine and mammary estrogen sulfurylation.

The steroid alcohol and estrogen sulfotransferases in rodent and human mammary tumors.

Rodent and human mammary tumor systems were investigated to relate the steroid alcohol and estrogen sulfotransferase activities to the hormoanl dependency of the tumor as determined by estrogen receptor content. Unlike the normal mammary gland or the hyperplastic alveolar nodule, rodent mammary neoplasms displayed significant levels of these two sulfotransferases. In the hormone-independent mouse tumors produced from out-growth lines D1, D2, and D8, high dehydroepiandrosterone sulfotransferase activity was characteristic of the rapidity with which hyperplastic alveolar nodules developed into a neoplasms (V-max = 52.8 versus 1.8 fmoles/min/mg protein) while estrone sulfotransferase activity was either not detectable or low (V-max = 5.5 fmoles). After oophorectomy of mice bearing slowly developing tumors, both sulfotransferases in the nonregressing neoplasms showed marked increases in activity (V-max dehydroepiandrosterone = 30.0 fmoles; V-max estrone = 18.5 fmoles). Strain differences not the estrogen receptor content of hormone-dependent rat mammary tumors. In Wistar-Lewis rats the steroid alcohol sulfotransferase activity was at least 35 times higher than in the Sprague-Dawley strain. As was observed in the mouse mammary tumor, Sprague-Dawley rat neoplasms that grew in the absence of ovarian hormones contained significantly greater levels of the steroid alcohol sulfotransferase. Possible correlaion between presence of the steroid alcohol sulfotransferase and the estrogen receptor protein was observed in a limited number of human breast carcinomas.