Amyloid deposition in 2 feline thymomas.

Two cases of feline thymoma with amyloid deposition were encountered between 1982 and 2010. Neoplastic cells were separated by abundant, pale eosinophilic, homogeneous material that was congophilic and birefringent. Ultrastructurally, the neoplastic cells were connected by desmosomes, and the extracellular deposits were composed of nonbranching, hollow-cored fibrils, 8-10 nm in diameter. In the case with sufficient archived tissue for additional sections, the amyloid remained congophilic following potassium permanganate incubation, and the neoplastic cells were immunoreactive for pancytokeratin. The histologic, histochemical, ultrastructural, and immunohistochemical features of both neoplasms are consistent with epithelial-predominant thymoma with the unusual feature of intratumoral amyloid deposition. The affinity of the amyloid for Congo red following potassium permanganate incubation is consistent with non-AA amyloid. The ultrastructural findings were consistent with amyloid production by the neoplastic epithelial cells.

Metastable phases in polar stratospheric aerosols.

Phase changes in stratospheric aerosols were studied by cooling a droplet of sulfuric acid (H(2)SO(4)) in the presence of nitric acid (HNO(3)) and water vapor. A sequence of solid phases was observed to form that followed Ostwald's rule for phase nucleation. For stratospheric partial pressures at temperatures between 193 and 195 kelvin, a metastable ternary H(2)SO(4)-HNO(3) hydrate, H(2)SO(4) . HNO(3) . 5H(2)O, formed in coexistence with binary H(2)SO(4) . kH(2)O hydrates (k = 2, 3, and 4) and then transformed to nitric acid dihydrate, HNO(3) . 2H(2)O, within a few hours. Metastable HNO(3) . 2H(2)O always formed before stable nitric acid trihydrate, HNO(3).3H(2)O, under stratospheric conditions and persisted for long periods. The formation of metastable phases provides a mechanism for differential particle growth and sedimentation of HNO(3) from the polar winter stratosphere.

Vapor pressures of solid hydrates of nitric Acid: implications for polar stratospheric clouds.

Thermodynamic data are presented for hydrates of nitric acid: HNO(3).H(2)O, HNO(3).2H(2)O, HNO(3).3H(2)O, and a higher hydrate. Laboratory data indicate that nucleation and persistence of metastable HNO(3).2H(2)O may be favored in polar stratospheric clouds over the slightly more stable HNO(3).3H(2)O. Atmospheric observations indicate that some polar stratospheric clouds may be composed of HNO(3).2H(2)O and HNO(3).3H(2)O. Vapor transfer from HNO(3).2H(2)O to HNO(3).3H(2)O could be a key step in the sedimentation of HNO(3), which plays an important role in the depletion of polar ozone.

Circadian regulation of iodopsin gene expression in embryonic photoreceptors in retinal cell culture.

A circadian clock regulates a number of diverse physiological functions in the vertebrate eye. In this study, we show that mRNA for the red-sensitive cone pigment, iodopsin, fluctuates with a circadian rhythm in chicken retina. Transcript levels increase in the late afternoon just prior to the time of cone disc shedding. Furthermore, iodopsin mRNA levels are regulated similarly by a circadian oscillator in primary cultures of dispersed embryonic chick retina. Nuclear run-on experiments show that the circadian regulation of iodopsin transcript abundance occurs at the level of gene transcription. Our results provide a demonstration of clock-regulated gene expression in a vertebrate preparation maintained in cell culture.

Accumulation of c-src mRNA is developmentally regulated in embryonic neural retina.

Accumulation of c-src mRNA gradually increased during early development of the neural retina in chicken embryos and reached a peak by days 11 to 13 of embryonic life. Thereafter, its amount declined to a low level which persisted also in adult retina. The early increase in c-src mRNA correlated inversely with the decrease in the amount of H3.2 replication histone mRNA and with the decline in the rate of cell growth. The accumulation profile of c-src mRNA corresponded to that of pp60c-src protein, suggesting that the latter is regulated at the level of transcription.

Expression of v-src in embryonic neural retina alters cell adhesion, inhibits histogenesis, and prevents induction of glutamine synthetase.

Using Rous sarcoma virus as the vector, v-src or c-src genes were introduced into 6-day chicken embryo retina tissue in organ culture and their effects on retina development were investigated. Overexpression of c-src in many of the cells had no noticeable effect on retina development. In contrast, infection with v-src resulted in abnormal histogenesis and inhibition of differentiation. Although only a portion of the cells in infected tissue expressed the oncogene and displayed the transformation phenotype, the other cells were also hindered from becoming normally positioned and organized. Therefore, presence of oncogene-transformed cells within the tissue hindered organization and development of adjacent nontransformed cells. Failure of normal cell relationships impeded induction by cortisol of glutamine synthetase in Muller glia, which requires contact associations of the glia cells with neurons. The transformed cells tended to assemble into chaotic clusters, suggesting that their adhesiveness and contact affinities had become altered. This was confirmed by aggregation experiments with dissociated cells which showed that adhesiveness of transformed cells was greatly reduced and that they had lost the ability to cohere with nontransformed cells. In binary mixtures of transformed and nontransformed cells, the two sorted out into separate aggregates. Transformed cells formed loose clusters devoid of tissue architecture; aggregates of nontransformed cells became organized into retinotypic structures, and glutamine synthetase was inducible. Our findings suggest that the mechanisms of cell adhesion and cell affinities are a key target of v-src activity in infected cells and that modification of the cell surface may be a leading factor in other cellular changes characteristic of the v-src transformation phenotype.

Adjuvant therapy for osteosarcoma in dogs: results of randomized clinical trials using combined liposome-encapsulated muramyl tripeptide and cisplatin.

Two randomized, double-blind clinical trials in dogs with spontaneous appendicular osteosarcoma treated with combination chemoimmunotherapy are reported. In both trials, dogs without overt metastasis underwent complete amputation of the affected limb. In trial 1, 40 dogs were treated with cisplatin chemotherapy [(CDDP), 70 mg/m2 i.v. every 28 days x 4]. Following CDDP, dogs without evidence of overt metastasis (n = 25) were randomized to receive liposome-encapsulated muramyl tripeptide phosphatidylethanolamine ](L-MTP-PE), 2 mg/m2 i.v.) or placebo liposomes (lipid equivalent) twice weekly for 8 weeks. Of 14 dogs in the placebo group, 13 (93%) died of metastasis; the median survival time was 9.8 months. Of 11 dogs in the L-MTP-PE group, 8 (73%) developed metastasis; the median survival time was 14.4 months, which was significantly longer than that of the placebo group (P < 0.01). In trial 2, 64 dogs received CDDP (70 mg/m2 i.v. every 21 days x 4) and were randomized to concurrently receive L-MTP-PE (2 mg/m2 i.v.) twice or once weekly, or placebo liposomes once weekly for 8 weeks. Median survival times were 10.3, 10.5, and 7.6 months, respectively. There were no significant differences among the three treatment groups in trial 2. Survival times for dogs receiving L-MTP-PE in trial 1 were significantly longer than those for dogs in trial 2 that received four doses of CDDP concurrently with twice weekly L-MTP-PE (P < 0. 04). The results of the first trial confirm our previous observation that L-MTP-PE has antimetastatic activity in dogs with osteosarcoma when given following amputation. The results of the second trial demonstrate that there is no survival advantage of administering L-MTP-PE concurrently with CDDP.

Adjuvant therapy for melanoma in dogs: results of randomized clinical trials using surgery, liposome-encapsulated muramyl tripeptide, and granulocyte macrophage colony-stimulating factor.

Spontaneous canine oral melanoma (COM) is a highly metastatic cancer, resistant to chemotherapy, and can serve as a model for cancer immunotherapy. Liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine (L-MTP-PE) can activate the tumoricidal activity of the monocyte-macrophage system following i.v. injection. The objective of these studies was to evaluate the therapeutic effectiveness of L-MTP-PE administered alone and combined with recombinant canine granulocyte macrophage colony-stimulating factor (rcGM-CSF) in dogs undergoing surgery for oral melanoma. Ninety-eight dogs with histologically confirmed, clinically staged, oral melanoma were entered into two randomized, double-blind, surgical adjuvant trials. In trial 1, 50 dogs were stratified based on clinical stage and randomized to once a week L-MTP-PE or lipid equivalent (control). When all of the clinical stages were combined, no difference in disease-free survival or in survival time (ST) were detected. However, within stage I, dogs receiving L-MTP-PE had a significant increase in ST compared with control, with 80% of the dogs treated with L-MTP-PE still alive at >2 years. Within each stage II and stage III, there was no difference detected between the treatment groups. In trial 2, 48 dogs were stratified on the basis of clinical stage and extent of surgery (simple resection or radical excision), treated with L-MTP-PE two times a week, and randomized to rcGM-CSF or saline (placebo) given s.c. daily for 9 weeks. Within each stage and when all of the stages were combined, there was no difference between the treatment groups. In both studies, stage I COM is associated with a better prognosis. No effect on survival was observed with regard to tumor location in the oral cavity, sex, type/extent of surgery, or age. In a subset of dogs tested, pulmonary alveolar macrophage cytotoxicity was enhanced with combined rcGM-CSF and L-MTP-PE but not in dogs treated with L-MTP-PE alone. The present study indicates that after surgery, L-MTP-PE administered alone or combined with rcGM-CSF showed no significant antitumor activity in treating advanced stage COM. In early stage COM, L-MTP-PE was shown to result in a prolongation of ST. Furthermore, this study provides additional rationale for the use of the dog model for human malignant melanoma.

Hormonal and non-hormonal regulation of glutamine synthetase in the developing neural retina.

Two isoforms of the glucocorticoid receptor, with apparent molecular mass of 90 and 95 kDa, are expressed in embryonic chicken neural retina. The 95-kDa receptor represents a hyperphosphorylated form of the 90-kDa receptor. Activation of the glucocorticoid receptor by cortisol results in a dose-dependent increase in receptor phosphorylation, translocation of receptor molecules into the nucleus and a decline in the total amount of the receptor. Activation of the glucocorticoid receptor can also be observed in the developing retinal tissue in ovo. At late embryonic ages, when the systemic level of glucocorticoids increases, a substantial quantity of receptor molecules becomes translocated into the nucleus, the relative level of the 95-kDa isoform increases, and the total amount of receptor declines. Activation of the receptor molecules in ovo correlates directly with an increase in transcription of the glucocorticoid-inducible gene, glutamine synthetase. The close correlation between the increase in systemic glucocorticoids, activation of glucocorticoid receptor molecules and induction of glutamine synthetase gene transcription suggests that glucocorticoids are directly involved in the developmental control of glutamine synthetase expression. Long-term organ culturing of embryonic retinal tissue in the absence of hormone results in an increase in glutamine synthetase expression. This increase, which is only 5 to 10% of that observed in ovo, is not mediated by activated receptor molecules and represents a mechanism for non-hormonal regulation of glutamine synthetase.

Molecular basis for differential expression of glutamine synthetase in retina glia and neurons.

Glutamine synthetase (GS) is a differentiation marker of retina glial cell. It is expressed in the chicken neural retina at a particularly high level, is inducible by glucocorticoids and is always confined to Müller glia. This study investigated the molecular basis for tissue and cell-type specific expression of the GS gene. A high level of GS expression in the retina was found to coincide with the accumulation of a relatively high level of GS mRNA in this tissue. The gliatoxic agent alpha-aminoadipic acid, which can selectively destroy glia cells, was used to demonstrate that restriction of GS induction to Müller glia is controlled at a transcriptional level. Cortisol could induce accumulation of GS mRNA and transcription of the GS gene in Müller glia but not in retina neurons. Glia and neurons were also found to differ in their ability to express the glucocorticoid inducible CAT construct, p delta G46TCO, which is controlled by a 'simple GRE' promoter. When introduced into cells of retina tissue, this construct was cortisol-inducible in glia whereas in neurons it was only slightly inducible or not at all. Introduction of a glucocorticoid receptor expression vector into the cells facilitated induction of the CAT construct in neurons. Analysis by immunoblotting revealed that expression of the glucocorticoid receptor protein is predominantly restricted to Müller glia. These results suggest that differential levels of glucocorticoid receptor expression in glia and neurons might be the basis for cell-type specific induction of GS.

Changes in patterns and synthesis of proteins in embryonic neural retina studied by 2-dimensional gel electrophoresis.

Changes in protein patterns during early differentiation of embryonic neural retina (chick) were studied by 2-dimensional gel electrophoresis. The procedures employed here made it possible to visualize the overall population of proteins present in the tissue at a given time and, on the same gel to distinguish labeled from unlabeled proteins. 2-Dimensional gels were stained by a highly sensitive silver stain to visualize, map and quantitate proteins (and polypeptides) resolved by electrophoresis; the same gels were then autoradiographed in order to differentiate between actively synthesized and pre-existing proteins at each development stage. The effectiveness of this combinative analysis was first verified by identifying and localizing glutamine synthetase, an inducible enzyme marker of retina differentiation. Next, protein patterns in retina tissue at 2 embryonic ages were compared. Of the large number of spots visualized by the above methods approximately 10% showed distinct qualitative-quantitative developmental changes; these were grouped into 7 classes representative of major modes of alteration of protein patterns during cell differentiation.

Blurred vision during sexual arousal associated with narrow-angle glaucoma.

PURPOSE: To describe three women with narrow-angle glaucoma who had transient blurred vision during sexual arousal. METHOD: Case reports. RESULTS: Three women, aged 37, 45, and 55 years, were seen with bilateral narrow-angle glaucoma and were treated with bilateral laser iridotomy. In each patient, additional surgery was required to control the glaucoma. After establishing a rapport with her physician, each patient described transient blurred vision, from a few minutes to several hours in duration, which began during sexual arousal. This symptom resolved after peripheral iridotomy and, in one patient, after laser iridoplasty. CONCLUSION: The association of transient blurred vision with sexual activity may delay presentation of patients with symptomatic narrow-angle glaucoma.

Biometric variables in patients with occludable anterior chamber angles.

Biometric studies of the ocular dimensions in eyes with narrow anterior chamber angles provide insight into the pathophysiology of pupillary block and may show which eyes are more prone to develop angle-closure glaucoma. We reviewed the records of 56 patients with occludable angles examined between 1980 and 1984. Initial biometric data obtained on the patients included corneal diameter, anterior chamber depth, lens thickness, and ocular axial length. The average length of follow-up was five years. Of 54 patients with complete clinical records, 20 (37%) eventually required peripheral iridectomy after a mean duration of 16 months from the initial examination. Cox's survival analysis showed a strong correlation between shortened duration to peripheral iridectomy and increasing lens thickness/ocular axial length ratio factor (P = .03). No other variables were significantly related to outcome. This suggests that the lens thickness/ocular axial length ratio may be useful as a predictor of clinical outcome in narrow-angle glaucoma.

Current studies of liposome muramyl tripeptide (CGP 19835A lipid) therapy for metastasis in spontaneous tumors: a progress review.

Targeted delivery of macrophage activating agents is an attractive approach to treat micrometastatic disease. Liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (L-MTP-PE) is a potent activator of monocytes/macrophages in humans, mice, and dogs. We have conducted clinical trials in dogs with malignant and highly metastatic spontaneous tumors. Presented are results of our trials evaluating L-MTP-PE in combination with surgery and chemotherapy in dogs with spontaneous osteosarcoma and hemangiosarcoma, particularly relevant malignancies having having many similarities to human cancer. Osteosarcoma dogs received chemotherapy following surgery (cisplatin q 28 days x 4). At completion of chemotherapy, dogs were randomized to receive L-MTP-PE or placebo. The L-MTP-PE group had a significantly longer median survival time compared to the placebo group (p < 0.021). Dogs with splenic hemangiosarcoma received combination chemotherapy following surgery (doxorubicin and cyclophosphamide q 21 days x 4). At the first chemotherapy, dogs were randomized to receive L-MTP-PE or placebo. The L-MTP-PE group had a significantly longer median survival time compared to the placebo group (p < 0.03). These studies show that L-MTP-PE is an effective agent for treatment of metastasis and can be safely administered in combination with chemotherapy.

Feline bone marrow transplantation: its use in FIV-infected cats.

The use of autologous and allogenic bone marrow transplantations (BMT) in FIV-infected and uninfected cats is a novel therapy for feline hematopoietic diseases and retroviral infections. A total of 13 specific pathogen-free (SPF) cats received either autologous or allogenic BMT and seven of these cats were also infected with FIV before autologous or allogenic BMT. All BMT recipients received total body irradiation of 900 cGy just before BMT. Two FIV-infected and four uninfected cats received autologous uninfected BM cells cryopreserved before BMT. Five infected and two uninfected cats received BM cells from allogenic uninfected donors (RBC-, MHC-, and cross-matched). MHC-matching was based on mixed leucocyte reaction (MLR) and the donor-recipient combination which was compatible by MLR analysis, was used in this study. Recipients were monitored for hematology, immunology, virology, and clinical signs. All FIV-infected and uninfected recipients of autologous BMT had complete engraftment with minimal complications. Uninfected recipients of allogenic BMT had a more severe clinical episode with slower rate of engraftment. None of these BMT groups had mortality. In contrast, only two of the five infected recipients of allogenic BMT survived for a significant period of time (23 and 50 weeks) and rest of the cats succumbed to transfusion reactions. Both infected BMT groups had persistent CD4/CD8 inversion, low CD4+ cell counts, and FIV infection of engrafted peripheral blood mononuclear cells (PBMC). Overall, successful autologous and allogenic BMTs were performed in FIV-free cats. All infected recipients of autologous BMT had compete engraftment and are currently alive, with thelongest survival time being over 1 year. Thus, BMT in combination with antiviral drug therapies may be an alternative therapy against retroviral infection.

Malignant jugulotympanic paraganglioma in a dog.

An invasive malignant epithelial neoplasm was diagnosed as a paraganglioma by light and electron microscopy and immunohistochemically by a positive reaction with anti-neuron-specific enolase. Due to the extensive involvement of the middle ear, a primary origin in the jugulotympanic or jugular paraganglia is suggested.

Cutaneous hemangiosarcoma in 25 dogs: a retrospective study.

Hemangiosarcomas confined to the skin and underlying muscle were surgically excised in 25 dogs. Tumors were staged based on their histological location (ie, dermal, hypodermal, and deep). Dermal (stage I) hemangiosarcomas were small, most commonly ventral-abdominal or prepucial in location, and were associated with prolonged survival times (median survival, 780 days). Tumors with hypodermal (stage II) and underlying muscular involvement (stage III) were grouped together because of their larger size, bruise-like appearance, lack of anatomic predilection, biological behavior, and shorter survival times (median survival of 172 and 307 days for dogs with stages II and III, respectively). We conclude that dermal hemangiosarcomas may be effectively treated with surgery alone, whereas hemangiosarcomas located within the hypodermal tissues bear a poor prognosis and warrant wide surgical excision with adjuvant chemotherapy.

Evaluation of prognostic factors and sequential combination chemotherapy with doxorubicin for canine lymphoma.

Fifty-five dogs with lymphoma were treated using a doxorubicin-based sequential combination chemotherapy protocol. Complete response, partial response, and no response were seen in 46, 4, and 5 dogs, respectively. The overall median remission duration and survival times were 36 and 51 weeks, respectively. Age, sex, weight, World Health Organization stage, World Health Organization substage (i.e., a = not ill, b = ill), serum calcium concentration, blood urea nitrogen concentration, breed and protocol alteration secondary to toxicity were evaluated for prognostic significance. Univariate analysis of prognostic factors identified sex, World Health Organization substage, and serum calcium as statistically significant (P < or = .05) variables for both survival and remission duration. Upon multivariate analysis, only substage (P = .036) was a significant prognostic factor for remission duration, whereas, both substage (P = .006) and sex (P = .005) were significant prognostic factors for survival.

Primary ciliary dyskinesia in the dog.

Electron microscopy was used to diagnose primary ciliary dyskinesia in a litter of English pointer dogs and in a golden retriever dog. A technique of membrane solubilization, fixation, and negative staining with glutaraldehyde tannic acid identified abnormally constructed central and B microtubules in respiratory cilia from dogs with primary ciliary dyskinesia. Shortened outer dynein arms commonly associated with primary ciliary dyskinesia actually represents the absence of a specific subset of the three most peripheral components of the whole outer dynein arm structure.

Evaluation of L-asparaginase: polyethylene glycol conjugate versus native L-asparaginase combined with chemotherapy. A randomized double-blind study in canine lymphoma.

L-asparaginase is an enzyme that inhibits protein synthesis by the depletion of sources of L-asparagine, which is necessary for transformed lymphoid cells to proliferate. L-asparaginase is used in the treatment of childhood acute lymphoblastic leukemia. A problem with L-asparaginase therapy is the immunogenicity of the enzyme and the development of anaphylactic reactions. Canine lymphoma is a predominantly B-cell tumor with widespread disease; without treatment, dogs with lymphoma usually survive 1-2 months. Canine lymphoma will respond to L-asparaginase therapy. A randomized double-blind study evaluated a polyethylene glycol (PEG) conjugate L-asparaginase combined with chemotherapy (vincristine, cyclophosphamide, doxorubicin, and prednisone). Thirty-five dogs were randomized to the PEG L-asparaginase group, and 34 dogs were randomized to the native L-asparaginase group. Thirty dogs (85.7%) achieved a complete remission (CR) with a median time to relapse of 217 days, and 32 (94.1%) dogs in the native L-asparaginase group achieved a CR with a median time to relapse of 214 days (P greater than 0.05). The asparaginase was well tolerated in both groups. Two dogs in the native L-asparaginase group had severe allergic reactions, and one dog in the PEG asparaginase group had a generalized urticarial reaction after repeated injections. This study indicates that PEG L-asparaginase has equal therapeutic efficacy to native L-asparaginase.