The usefulness of immunohistochemistry to differentiate between nasal carcinoma and lymphoma in cats: 140 cases (1986-2000).

A retrospective evaluation of 232 feline nasal biopsies initially diagnosed as either carcinoma or lymphoma was performed by two pathologists. One or both pathologists disagreed with the original diagnosis in 15 cases (7%), 14 of which had original diagnoses of carcinoma. Out of the 232 cases, 140, including the disputed ones, were subjected to immunohistochemical staining with epithelial and lymphoid markers. Immunohistochemical staining of the 15 disputed cases showed that the original diagnoses were incorrect in 67% (10/15), unverified in 13% (2/15) and correct in 20% (3/15). Among the consensual diagnoses, immunohistochemistry revealed that 3% (4/125) of diagnoses were unverified because they did not stain for any of the markers evaluated. This report demonstrates the importance of immunohistochemistry in establishing a correct histologic diagnosis for nasal neoplasms in cats.

Postnatal neurogenesis: of mice, men, and macaques.

Over the past 20 years, the conception of brain development has radically changed from a fixed and limited hierarchical process to a more plastic and continuous one. Most surprising, the field has learned that postnatal neurogenesis is not just a seasonal phenomenon in songbirds but a process that occurs across species and seasons. Astrocytes, whose primary role in the central nervous system was thought to be strictly supportive, have emerged as a heterogeneous population, a subset of which is the neural stem cell. Postnatal neurogenesis persists in specialized niches within the rostral subventricular zone and hippocampal dentate gyrus and, for a limited period, within the white matter tracts and external granular layer of the cerebellum. These specialized microenvironments are influenced by factors in the blood, cerebrospinal fluid, and local extracellular matrix. This article reviews the current understanding of adult neurogenesis, which is conserved across many vertebrate species, underscoring the value of animal models in past and present studies of human neurogenesis and neurogenic disease.

Magnetic resonance imaging as a tool for monitoring stem cell migration.

Noninvasive monitoring of stem cells is an important step in developing stem-cell-based therapies. Among several imaging techniques available, magnetic resonance imaging (MRI) provides an effective way to detect implanted stem cells in live animals. In this mini-review, we discuss the available MRI contrast agents and different cell-labeling strategies used for detection of stem cell migration in the brain. The potential effects of MRI contrast agents on stem cell viability and differentiation are also discussed.

In vivo and ex vivo MRI detection of localized and disseminated neural stem cell grafts in the mouse brain.

The application of stem cells as delivery vehicles opens up the opportunity for targeting therapeutic proteins to the damaged or degenerating central nervous system. Neural stem cell (NSC) lines have been shown to engraft, differentiate and correct certain central nervous system diseases. The present study was performed to test the ability of magnetic resonance imaging (MRI) in detecting transplanted NSCs under conditions of limited migration in the normal adult mouse brain versus widespread migration when the cells are transplanted neonatally. The C17.2 NSC line was labeled in vitro with superparamagnetic iron oxide (SPIO) particles and the labeled cells were implanted intracranially. Serial in vivo gradient echo MR imaging was performed using a 4.7 T horizontal bore magnet. High resolution ex vivo images of the isolated brains were performed at 9.4 T, and the presence of iron was correlated with Prussian blue staining in histological sections. Adult animals injected with SPIO-labeled stem cells exhibited hypointense regions near the injection site that were observed up to 32 days after injection. In neonatally transplanted animals, MR signal intensity from transplanted NSCs was not apparent in in vivo imaging but ex vivo MR images revealed small hypointense regions throughout the brain including the olfactory bulbs, cortex and the cerebellum, reflecting the wide distribution of the engrafted cells. These regions were correlated with Prussian blue staining, which confirmed the presence of SPIO particles inside the engrafted cells. We have shown that MRI is capable of differentiating localized and widespread engraftment of C17.2 stem cells in the central nervous system.

Feline Hodgkin's-like lymphoma: 20 cases (1992-1999).

We identified 20 cases of feline lymphadenopathy that conform to many clinical and histologic manifestations of human Hodgkin's disease. Histologic subtypes encountered included lymphocyte predominance (nine cases), mixed cellularity (nine cases), and nodular sclerosis (two cases). Two cases were not easily classified; fibrous bands were present, but the absence of nodules supported a subclassification of mixed cellularity Hodgkin's disease. Immunohistochemical staining of the tissues using antibodies against the pan T-cell antigen CD3, the human B-lymphocyte antigen 36 (BLA.36), the pan B-lymphocyte and plasma cell marker CD79a, and a myeloid antigen (MAC387) confirmed the phenotypic heterogeneity of the tumor. Classic Reed-Sternberg (RS) cells and mononuclear, multinucleate, and lacunar cell variants did not stain with any of the antibodies used. In contrast, lymphohistiocytic RS variants (L+H cells) reacted positively to BLA.36 and CD79a B-cell markers. Eighteen of 20 affected cats were > or = 6 years of age (range, 1-14 years). A sex predilection could not be identified. These findings support the existence of Hodgkin's-like lymphoma in the cat. Proper identification of this disease in the cat will enable further characterization of clinical features and biologic behavior to determine whether there are significant differences in the treatment and prognosis of feline Hodgkin's-like lymphoma compared with non-Hodgkin's lymphoma.

Effects of triamcinolone acetonide on an in vivo equine osteochondral fragment exercise model.

The objective of this study was to determine the effects of intra-articularly administered triamcinolone acetonide (TA) in exercised equine athletes with carpal osteochondral fragmentation. Eighteen horses were randomly assigned to each of 3 groups. An osteochondral chip fragment was created in one randomly chosen intercarpal joint of each horse. Both intercarpal joints in the placebo control group (CNT) horses were injected with intra-articular administration (IA) of polyionic fluid. Both joints in the TA control group (TA CNT) horses were treated with 12 mg of TA in the intercarpal joint without an osteochondral fragment, and the opposite intercarpal joint was injected with a similar volume of polyionic fluid. The TA treated group (TA TX) horses were treated with 12 mg of TA in the joint that contained the osteochondral fragment and the opposite intercarpal joint was injected with a similar volume of polyionic fluid. All horses were treated IA on days 13 and 27 after surgery and exercised on a high speed treadmill for 6 weeks starting on Day 14. Horses in the TA TX group were significantly less lame than horses in the CNT and TA CNT groups. Horses in either TA CNT or TA TX groups had lower total protein, and higher hyaluronan, and glycosaminoglycan concentrations in synovial fluid than did those in the CNT group. Synovial membrane collected from subjects in TA CNT and TA TX groups had significantly less inflammatory cell infiltration, subintimal hyperplasia and subintimal fibrosis compared to the CNT group. Articular cartilage histomorphological parameters were significantly better from the TA CNT and TA TX groups compared to the CNT group. In conclusions, results from this study support favourable effects of TA on degree of clinically detectable lameness, and on synovial fluid, synovial membrane, and articular cartilage morphological parameters, both with direct intra-articular administration and remote site administration as compared to placebo treatment. The clinical use of IA administered TA in horses may be therapeutically beneficial in selected cases of osteochondral fragmentation and osteoarthritis.

Effects of intravenous administration of sodium hyaluronate on carpal joints in exercising horses after arthroscopic surgery and osteochondral fragmentation.

OBJECTIVE: To evaluate the effects of arthroscopic surgery, osteochondral fragmentation, and treatment with IV administered hyaluronate on histologic, histochemical, and biochemical measurements within the carpal joints of horses. ANIMALS: 12 clinically normal horses, 2 to 7 years of age. PROCEDURE: Horses had an osteochondral fragment created at the distal aspect of the radiocarpal bone of 1 randomly chosen middle carpal joint to simulate osteochondral fragmentation. Horses were treated with 40 mg of hyaluronate or saline solution (placebo) intravenously once a week for 3 consecutive weeks (days 13, 20, and 27 after surgery). Treadmill exercise proceeded 5 days per week beginning 15 days, and ending 72 days, after surgery. Clinical evaluations were performed at the beginning and end of the study. Synovial fluid samples were obtained aseptically from both middle carpal joints on days 0, 13, 20, 27, 34, and 72 after surgery, and total protein, inflammatory cell, hyaluronate, glycosaminoglycan, and prostaglandin E2 concentrations were measured in each sample. All horses were euthanatized on day 72. Synovial membrane and articular cartilage were obtained for histologic evaluation. Articular cartilage samples were also obtained aseptically for determining glycosaminoglycan content and chondrocyte synthetic rate for glycosaminoglycans. RESULTS: Horses treated with hyaluronate intravenously had lower lameness scores (were less lame), significantly better synovial membrane histologic scores, and significantly lower concentrations of total protein and prostaglandin E2 within synovial fluid 72 days after surgery, compared with placebo-treated horses. Treatment with intravenously administered hyaluronate had no significant effects on glycosaminoglycan content, synthetic rate or morphologic scoring in articular cartilage, or other synovial fluid measurements. CONCLUSION: Intravenously administered hyaluronate appears to alleviate signs of lameness by interacting with synoviocytes, and by decreasing production and release of inflammatory mediators.

Mechanisms of echinocytosis induced by Crotalus atrox venom.

Transient echinocytosis has been reported in association with snake envenomation in humans and dogs. An in vitro model of echinocytosis induced by venom of crotalus atrox (western diamondback rattlesnake) was established to characterize erythrocyte morphologic changes and to investigate potential mechanisms of echinocytic transformation. Erythrocyte morphologic changes produced after the addition of venom to canine, feline, equine, and human blood were characterized by dose-dependent echinocytosis. Type III echinocytosis were consistently induced in vitro at a dose comparable to in vivo envenomation; higher venom doses produced spheroechinocytic and spherocytic transformations. The changes could not be induced in vitro in the presence of ethylenediaminetraacetic acid but were observed in heparinized and citrated blood samples, suggesting the participation of calcium or a metalloprotein in echinocytic change. These findings suggest that phospholipase A2 (PLA2), a calcium-dependent enzyme in snake venom, may be responsible for echinocytic transformation via the production of lysolecithin, a known echinocytic agent. Purified PLA2 from C. atrox venom induced dose-dependent echinocytic change in vitro in canine blood. Other potential mechanisms of echinocytic change evaluated in canine blood included erythrocyte cation loss and erythrocyte ATP depletion. In canine blood mixed with venom, erythrocyte sodium and potassium concentrations were consistently less than those of controls, likely as a result of membrane alteration produced by the actions of PLA2. There was no difference in blood ATP concentrations from dogs with snakebite when compared with normal controls; however, the power of this comparison was low. Echinocytosis induced by rattlesnake venom is related to the degree of venom exposure and may correlate clinically with the amount of venom absorbed. Echinocytic transformation in vitro is induced by PLA2 present in venom.

Malignant histiocytosis in a domestic cat: cytomorphologic and immunohistochemical features.

Malignant histiocytosis (MH) was diagnosed in a 13-year-old neutered male Domestic Shorthair cat on the basis of light microscopic and immunohistochemical findings. Thoracic fluid analysis showed a modified transudate which contained a very few atypical discrete cells. Cytologic and histologic evaluation of mediastinal and splenic masses revealed a pleomorphic population of large, discrete, round cells 10 to 30 micrometers in diameter with marked cellular atypia. Nuclei were oval to reniform, often with prominent, bizarre nucleoli. Multinucleated cells and mitotic figures were commonly seen. Erythro- and leucocytophagia were noted. Immunohistochemistry indicated a scattered positive staining pattern with the histiocytic antigenic marker Mac387 and a minor population of cells showing positive reactivity for lysozyme. This report describes the characterization of MH in a cat and emphasizes that MH should be considered as a differential diagnosis in proliferative disorders of discrete-cells in this species.

High-efficiency gene transfer into CD34+ cells with a human immunodeficiency virus type 1-based retroviral vector pseudotyped with vesicular stomatitis virus envelope glycoprotein G.

Currently, amphotropic retroviral vectors are widely used for gene transfer into CD34+ hematopoietic progenitor cells. The relatively low levels of transduction efficiency associated with these vectors in human cells is due to low viral titers and limitations in concentrating the virus because of the inherent fragility of retroviral envelopes. Here we show that a human immunodeficiency virus type 1 (HIV-1)-based retroviral vector containing the firefly luciferase reporter gene can be pseudotyped with a broad-host-range vesicular stomatitis virus envelope glycoprotein G (VSV-G). Higher-efficiency gene transfer into CD34+ cells was achieved with a VSV-G-pseudotyped HIV-1 vector than with a vector packaged in an amphotropic envelope. Concentration of virus without loss of viral infectivity permitted a higher multiplicity of infection, with a consequent higher efficiency of gene transfer, reaching 2.8 copies per cell. These vectors also showed remarkable stability during storage at 4 degrees C for a week. In addition, there was no significant loss of titer after freezing and thawing of the stock virus. The ability of VSV-G-pseudotyped retroviral vectors to achieve a severalfold increase in levels of transduction into CD34+ cells will allow high-efficiency gene transfer into hematopoietic progenitor cells for gene therapy purposes. Furthermore, since it has now become possible to infect CD34+ cells with pseudotyped HIV-1 with a high level of efficiency in vitro, many important questions regarding the effect of HIV-1 on lineage-specific differentiation of hematopoietic progenitors can now be addressed.

Bone marrow cytological findings in 4 dogs and a cat with hemophagocytic syndrome.

Hemophagocytic syndrome or hemophagic histiocytosis was diagnosed in 4 dogs and 1 cat by evaluation of bone marrow aspirate smears. One of the dogs had a suspected infection with canine parvovirus and a confirmed infection with Salmonella spp, 2 dogs had presumptive diagnoses of myeloproliferative and lymphoproliferative disease, respectively, and 1 dog died without a diagnosis. The cat had hepatic lipidosis and lesions compatible with feline calicivirus infection. All animals had cytopenias involving 2 or more cell lines, and fragmented erythrocytes in the blood, along with mild to moderate increases in the number of macrophages in the bone marrow. Numerous marrow macrophages contained phagocytized hematopoietic cells. Other cytological features of the bone marrow were variable in each patient, but the degree of response in the blood was inadequate, even in those with bone marrow hyperplasia. The phagocytosis of hematopoietic elements did not appear to be caused by a primary immune disorder, but rather by the inappropriate activation of normal macrophages secondary to infectious, neoplastic, or metabolic diseases. These findings suggest that hemophagocytic syndrome may be an important factor in the development of cytopenias; the data also support the cytological evaluation of bone marrow aspirates as an aid in the diagnosis of hemophagocytic syndrome.

Echinocytosis associated with rattlesnake envenomation in dogs.

A retrospective study of 28 cases of rattlesnake bites in dogs indicated an association of envenomation with echinocytosis; 25/28 dogs (89%) had echinocytosis within 24 hours of a rattlesnake bite being reported. Eighteen of the 28 dogs had marked type III echinocytosis (95-100% of mature erythrocytes affected), and seven dogs had moderate echinocytosis (15-30% of mature erythrocytes affected). The echinocytosis was transient, resolving within 48 hours of envenomation in those for which subsequent blood films were available (13/25). Hypokalemia was noted in 14 of 18 dogs for which biochemical data were available. The hypokalemia was not consistently associated with echinocytosis. The observation of echinocytosis in dogs supports a clinical diagnosis of rattlesnake envenomation.

The influence of ischaemia on the biliary tract.

Damage of the biliary tract at the end of a period of hepatic preservation prior to liver transplantation has been observed in man. This damage may be important in the development of early biliary complications. A model of hepatic biliary ischaemia in the pig has been developed which permits comparison between the influences of warm and cold ischaemic damage on the biliary tract. The major damage to the biliary tract in the pig in this model appears to occur after prolonged cold preservation.

Treatment of rhesus monkeys (Macaca mulatta) with intravaginal rings loaded with levonorgestrel.

The effects of levonorgestrel-releasing intravaginal rings were investigated in 15 rhesus monkeys for 52 weeks. The intravaginal rings were designed to provide a sustained release of either three or ten times the human dose level of the hormone. Untreated placebo rings were used as a control. The devices were well retained. After insertion of the vaginal rings, a dose-related decrease in vaginal bleeding was observed. The vaginal microbial flora were assessed qualitatively and semi-quantitatively and although all groups including controls showed some changes in microbial populations, by the end of the study nearly all animals returned to a normal balanced microflora. Terminal studies showed that, at the high dose level, ovulation was suppressed and widespread atrophy of the uterine mucosal and glandular epithelium had occurred. A dose-related increase in mucus within the lumen of the endocervical canal was observed. Focal or diffuse atrophy of the vaginal mucosal epithelium was seen in the majority of levonorgestrel-treated animals.

Treatment of rhesus monkeys (Macaca mulatta) with intravaginal rings impregnated with either progesterone or norethisterone.

The effects of both progesterone- and norethisterone-loaded intravaginal rings were investigated in twenty-five rhesus monkeys for 52 weeks. The intravaginal rings were designed to provide a sustained release of either the human dosage level of the hormone or ten times this level. Untreated placebo rings were used for control purposes. The devices were well retained. With the exception of increased plasma fibrinogen levels in animals treated with norethisterone, no marked differences in either local or systemic toxicity between the progesterone and norethisterone intravaginal rings were apparent. Following insertion of the hormone-treated intravaginal rings, a dose-related decrease in vaginal bleeding was recorded. The vaginal microbial flora were assessed qualitatively and semiquantitatively and all groups including the placebo controls showed a changes in mcirobial populations. Terminal studies indicated that at high dose levels, ovulation was suppressed and widespread atrophy of the uterine mucosal and glandular endometrial epithelium had occurred. An increase in cervical mucus was observed within the lumen of the endocervical canal in a proportion of hormone-treated animals. In the vagina, a dose-related focal or diffuse atrophy of the mucosal epithelium was found.

Treatment of rhesus monkeys (Macaca mulatta) with intrauterine devices loaded with levonorgestrel.

The effects of levonorgestrel-loaded plastic intrauterine devices on endometrial morphology were investigated in 15 rhesus monkeys for 14 weeks. The devices were designed to release 25 microgram of the hormone per day and were inserted in the uterus by hysterotomy. Control animals were sham operated or received inert placebo devices. With the levonorgestrel-releasing devices, widespread changes in endometrial morphology were seen. These changes included atrophy of the endometrial mucosal and glandular epithelium and decidualization of the endometrial stroma. With the inert placebo control devices, only minor changes in endometrial morphology were observed.