Correction of count losses due to deadtime on a DST-XLi (SmVi-GE) camera during dosimetric studies in patients injected with iodine-131

In dosimetric studies performed after therapeutic injection, it is essential to correct count losses due to deadtime on the gamma camera. This note describes four deadtime correction methods, one based on the use of a standard source without preliminary calibration, and three requiring specific calibration and based on the count rate observed in different spectrometric windows (20%, 20% plus a lower energy window and the full spectrum of 50-750 keV). Experiments were conducted on a phantom at increasingly higher count rates to check correction accuracy with the different methods. The error was less than +7% with a standard source, whereas count-rate-based methods gave more accurate results. On the assumption that the model was paralysable, preliminary calibration allowed an observed count rate curve to be plotted as a function of the real count rate. The use of the full spectrum led to a 3.0% underestimation for the highest activity imaged. As count losses depend on photon flux independent of energy, the use of the full spectrum during measurement allowed scatter conditions to be taken into account. A protocol was developed to apply this correction method to whole-body acquisitions.

IgE enhances Fc epsilon RI expression and IgE-dependent TNF-alpha release from canine skin mast cells

The role of IgE on mast cell (MC) activation is well known. Recent studies have demonstrated that IgE also has the ability to up-regulate the high affinity IgE receptor (Fc epsilon RI) on the surface of human and murine MC, leading to an increased production of cytokines and chemokines. In the present study, we have examined the influence of IgE levels on Fc epsilon RI expression, and its consequences on TNF-alpha production from canine skin MC. Mature MC were enzymatically dispersed from the skin biopsies of 6-8 dogs and were cultured for up to 5 days in medium supplemented with recombinant canine stem cell factor (SCF) (6 ng/ml), in the presence of increasing serum IgE concentrations (ranging from 0 to 80 microg/ml). Subsequently, skin MC were activated with anti-IgE, and TNF-alpha concentration was assessed 5h post-activation by a cytotoxic bioassay. Fc epsilon RI receptors were identified in MC surface by flow cytometry. MC cultured for up to 5 days in the presence of high serum IgE concentration (8 microg/ml) produced twice the quantity of TNF-alpha than MC cultured in the absence of serum IgE, in response to stimulation with anti-IgE. Moreover, the percentage of Fc epsilon RI-positive skin cells was found to be approximately double in cells cultured with serum IgE compared to that cultured in the absence of IgE, following saturation of IgE receptors. These results suggest that, as found in human and murine MC, IgE may induce an up-regulation of the Fc epsilon RI density and an enhancement in the secretory activity of canine skin MC. This study could be of great interest in designing new therapeutic strategies for controlling MC activation in inflammatory and allergic processes.

Evaluation of the efficacy of two leishmanins in asymptomatic dogs

There are few studies in dogs concerning leishmanin skin test. We evaluated and compared the efficacy of two leishmanin preparations for the detection of dog Leishmania cellular-mediated immunity. Clinically healthy dogs living in an endemic area were studied. A leishmanin preparation 1 (3 x 10(8) promastigotes/ml) was superior to a leishmanin preparation 2 (5 x 10(6) promastigotes/ml), measured as the percentage of positive reactions and the diameter of the induced induration. The leishmanin skin test is a valuable tool, although the results show that the degree of response, as it has been shown in human beings, depends on the preparation used.

Assessment of proliferative activity of canine dermal mast cells by bromodeoxyuridine and proliferating cell nuclear antigen labelling

Cutaneous mast cells from skin biopsies of three healthy dogs and three dogs with atopic dermatitis were assessed for their proliferative potential using bromodeoxyuridine and proliferating cell nuclear antigen labelling. Mast cells isolated from the skin of two healthy dogs were also studied using bromodeoxyuridine labelling. Mast cells in skin biopsy specimens and mast cells isolated from the skin of healthy dogs did not incorporate bromodeoxyuridine. Two mast cells expressing proliferating cell nuclear antigen were seen around two superficial vessels in the dermis of one atopic dog. Epidermal cells, glandular epithelial cells, fibroblasts and endothelial cells incorporated bromodeoxyuridine and showed positive staining for proliferating cell nuclear antigen. These results suggest that canine mature mast cells do not proliferate in the dermis.

Histopathological study of feline eosinophilic dermatoses

A retrospective study was conducted on skin specimens from 24 cats with eosinophilic granuloma complex. The specimens were stained with haematoxylin and eosin and Gallego's trichrome stain. In all specimens, flame figures and/or large foci of so-called "collagen degeneration" were detected and histopathological features were not predictive of the clinical picture. Use of the term eosinophilic dermatosis was advocated in diagnostic dermatopathology. On trichrome-stained sections, normally stained collagen fibres were identified in the middle of both flame figures and large foci of "collagen degeneration" and the debris surrounding collagen bundles showed the same tinctorial properties as eosinophil granules. Eosinophil degranulation around collagen bundles seemed to represent the major pathogenetic event in these lesions, analogous with human flame figures. The term flame figures might therefore be more accurately used to designate those foci of eosinophilic to partly basophilic debris commonly referred to as "collagen degeneration".

Traction alopecia with vasculitis in an Old English sheepdog

A seven-year-old entire male Old English sheepdog was presented with a well circumscribed, completely alopecic area on the top of its head, located where a rubber band had been used for several years. A punch biopsy was taken from the centre of the lesion and histological examination revealed cell-poor, interface mural folliculitis with follicular atrophy and vasculitis. A diagnosis of traction alopecia was made. Oral pentoxyfilline, at 400 mg twice daily, was prescribed for two months, with a slight improvement. To the authors' knowledge, this is the first report of canine traction alopecia accompanied by vascular damage. This vascular damage may represent the pathomechanism of this type of alopecia in the dog.

Leishmania infantum-specific IgG, IgG1 and IgG2 antibody responses in healthy and ill dogs from endemic areas. Evolution in the course of infection and after treatment

The expression of IgG, IgG1 and IgG2 specific antibodies for Leishmania infantum was studied in five groups of dogs in Catalonia (Spain): I, 99 asymptomatic dogs (infected and uninfected) from a highly endemic area for leishmaniosis; II, 139 untreated dogs with clinically patent leishmaniosis; III, 11 naturally infected asymptomatic dogs monitored for up to 5 years since they were found seropositive to Leishmania antigen and without treatment; IV, 25 naturally infected dogs with clinically patent leishmaniosis and treated with either meglumine antimoniate and allopurinol or allopurinol alone and V, six experimentally infected dogs, treated with meglumine antimoniate and controlled for 5 years. The levels (ELISA units) of IgG, IgG1 and IgG2 in asymptomatic dogs (group I) were very variable (24+/-33, 32+/-31 and 26+/-31, respectively), and, as expected, lower than in ill dogs (group II) (168+/-34, 84+/-71 and 172+/-31, respectively). In both groups, the correlation between IgG and IgG2 levels (r=0.95, P<0.001 in group I and r=0.63, P<0.001 in group II) was higher than between IgG and IgG1 levels (r=0.01, P>0.05 in group I and r=0.31, P<0.001 in group II). In group III, IgG and IgG2 expression increased during infection, while IgG1 expression remained the same. In dogs of group IV, IgG levels after 1 year of treatment decreased more in responsive (mean values, 163+/-42 before treatment (b.t.) and 100+/-36 after treatment (a.t.)) than in unresponsive dogs (158+/-29 b.t. and 124+/-51 a.t.), especially for IgG1 (94+/-89 b.t. and 20+/-21 a.t. in responsive dogs and 35+/-25 b.t. and 22+/-13 a.t. in unresponsive dogs) rather than for IgG2 (156+/-16 b.t. and 114+/-45 a.t. in responsive and 151+/-11 b.t. and 125+/-36 a.t. in unresponsive dogs). Similar results were observed in the evolution of experimentally infected animals after consecutive and specific treatments. Overall results show the great variation in Leishmania-specific IgG1 expression in asymptomatic and symptomatic dogs, their lack of correlation with that of IgG2 and chemotherapy is more effective in dogs with initially high expression of IgG1.

Prevalence of Leishmania infantum infection in dogs living in an area of canine leishmaniasis endemicity using PCR on several tissues and serology

We studied and compared the prevalence of Leishmania infection and the seroprevalence and the prevalence of canine leishmaniasis in an area where canine leishmaniasis is endemic. One hundred dogs living on the island of Mallorca (Spain) were studied. In this study, we clinically examined each dog for the presence of symptoms compatible with leishmaniasis, determined the titer of anti-Leishmania antibodies, and investigated the presence of Leishmania DNA by PCR in skin, conjunctiva, and bone marrow samples of each dog. The prevalence of the disease and the seroprevalence were 13 and 26%, respectively. In 63% of the dogs, Leishmania DNA could be detected by PCR in at least one of the tissues studied. The results of positive PCR in the bone marrow, the conjunctiva, and the skin were 17.8, 32, and 51%, respectively. The prevalence of the infection, 67%, was calculated using all animals that were seropositive and/or positive by PCR with any tissue. The results showed that the majority of dogs living in an area where canine leishmaniasis is endemic are infected by Leishmania and that the prevalence of infection is much greater than the prevalence of overt Leishmania-related disease.

The Ibizian hound presents a predominantly cellular immune response against natural Leishmania infection

Veterinarians working in the Balearic Islands (Mallorca), an endemic region of canine leishmaniosis, have reported very few cases of leishmaniosis in Ibizian hounds while concurrently observing that dogs of other breeds had a high incidence of clinical canine leishmaniosis. To further investigate this observation, two populations of dogs from the Balearic Islands were examined for the presence of Leishmania-specific cellular immunity using a delayed type hypersensitivity test (DTH) to leishmanin and for the presence of Leishmania-specific humoral immunity using an ELISA. Fifty-six asymptomatic dogs, 31 Ibizian hounds and 25 dogs belonging to other breeds were examined. Seventy-seven percent of the dogs demonstrated a specific immune response against Leishmania, either humoral or cellular. This finding suggests that the infection rate (77%) was higher than previously considered. For Ibizian hounds 81% were DTH positive while only 48% of the other dogs were DTH positive. A statistical association between Ibizian hounds and positive DTH response was found. A specific humoral response was found in 48% of Ibizian hounds and in 56% of the other dogs. No statistical association relative to the Leishmania-specific IgG1 and IgG2 levels were found between the two groups. The Ibizian hound has been reported to be more resistant to Leishmania infection and we found that the Ibizian hound mounts a significant cellular response to infection. Thus, the Ibizian hound may be an interesting canine model for the investigation of protective anti-Leishmania immune response.

Electron microscopy in pathology articles: a retrospective appraisal

Electron microscopy (EM) is a valuable standard tool in basic research and teaching. However, its use in diagnosis is limited, either for strategic reasons or budgetary constraints. This means that its many potential applications are more often neglected, either as an ancillary tool, quality control method, or gold standard, to complement, support, or confirm results of pathological studies. To evaluate the use of EM in this setting, the authors analyzed all articles (n = 2,531) in the three top indexed diagnostic pathology journals for a period of 60 months from July 1993 to June 1998. A total of 448 articles in which the use of EM was indicated, according to standard surgical pathology textbooks, were selected. Both the actual and the potential EM content of each article were scored, as follows: zero, illustrative, supportive, gold standard (for confirmation of research results), extensive, and predominant. Of the total number of articles in which EM was indicated, 77% made use of the technique. EM support was lacking most frequently in articles on serosal neoplasms and on new diagnostic strategies (p < .00005). There was no definite trend toward an increase or decrease in the use of EM during the period analyzed. The authors conclude that EM is used in most reports on diagnostic pathology, when it is indicated. However, a small but non-negligible percentage of articles (23%) could benefit from including EM as an ancillary, control, or gold standard method to complement, support, or confirm their results.

Canine mast cell tumors express stem cell factor receptor

c-kit protooncogene encodes a type III transmembrane receptor kinase, the stem cell factor receptor, or KIT. The ligand of the KIT. stem cell factor, is a cytokine that stimulates mast cell growth and differentiation. We have studied immunohistochemically KIT expression in 23 canine mast cell tumors (MCTs), 10 histiocytomas, 5 malignant melanomas, and in 2 cell lines derived from mast cells (HMC-1, human and C2, canine). As expected, KIT was detected both in the human mast cell leukemia cell line (HMC- ) and in the canine mastocytoma cell line C2. In normal canine skin, KIT expression was confined to mast cells. All canine MCTs expressed KIT, although the intensity of the staining reaction varied considerably among the 23 neoplasms. Grade III tumors showed the highest expression of KIT, whereas grade I tumors showed the lowest expression of KIT. Two patterns of KIT expression were detected in mast cells. In normal canine mast cells and in some neoplastic mast cells, KIT appeared mainly on the cell membrane. However, in many canine MCTs, KIT is accumulated in the cytoplasm, usually near the cell nucleus. The meaning of these two patterns is not clear. Expression of KIT could not be detected immunohistochemically in any of the other neoplasias investigated. According to our results, it can be concluded that most, if not all, canine MCT express KIT. Furthermore, there is an inverse correlation between the degree of differentiation and the expression of KIT. Moreover, according to our results, KIT can be used as a reliable immunohistochemical marker for canine mast cells and undifferentiated mast cell tumors.

Heterotopic sternum transplant in rats: A new model of a vascularized bone marrow transplantation

We introduced the heterotopic vascularized sternum transplant as a more simple and pure alternative to allogeneic hind limb transplantation for the study of bone marrow transplantation. We report the clinical and histopathological manifestations after transplantation of syngeneic and allogeneic sternal grafts with and without immunosuppression with FK-506. Syngeneic grafts maintained normal histology, whereas allografts showed rejection, which was prevented by FK-506. FK-506-treated allografts developed chimerism that was present throughout the observation period. Transplantation of the sternum may be a valuable model to study vascularized bone marrow transplantation and its effects on repopulation of bone marrow of the host, chimerism, and tolerance.

Radioimmunotherapy in medullary thyroid cancer using bispecific antibody and iodine 131-labeled bivalent hapten: preliminary results of a phase I/II clinical trial

The toxicity and therapeutic efficacy of escalating doses of anti-carcinoembryonic antigen x anti-N alpha-(diethylenetriamine-N,N,N',N''-tetraacetic acid)-In bispecific monoclonal antibody (F6-734) and iodine 131-labeled bivalent hapten were determined in a Phase I/II trial. A total of 26 patients with recurrences of medullary thyroid cancer documented by imaging and a rise in serum thyrocalcitonin were enrolled. Twenty to 50 mg of F6-734 and 40-100 mCi of 131I-hapten were injected 4 days apart. Quantitative scintigraphy was performed after the second injection for dosimetry estimations in eight cases. Clinical, biological, and morphological follow-up was carried out for 1 year after treatment. The mean percentage of injected activity per gram of tumor at the time of maximum uptake was 0.08% (range, 0.003-0.26%). The tumor biological half-life ranged from 3 to 95 days, and tumor doses ranged from 2.91 to 184 cGy/mCi. The estimated tumor-to-nontumor dose ratios were 43.8 x 53.4, 29.6 x 35.3, 10.9 x 13.6, and 8.4 x 10.0 for total body, red marrow, liver, and kidney, respectively. Grade III/IV hematological toxicity was observed in seven patients, most of them with bone metastases. Among the 17 evaluable patients, 4 pain reliefs, 5 minor tumor responses, and 4 biological responses with decrease of thyrocalcitonin were observed. Nine patients developed human anti-mouse antibody. Dose-limiting toxicity was hematological, and maximum tolerated activity was 48 mCi/m2 in this group of patients, most of whom had suspected bone marrow involvement. The therapeutic responses observed in patients mainly with a small tumor burden are encouraging for the performance of a Phase II trial with minimal residual disease.

Clinical anti-inflammatory efficacy of arofylline, a new selective phosphodiesterase-4 inhibitor, in dogs with atopic dermatitis

Forty atopic dogs were studied for 28 days after the oral administration of four randomised treatments: (A) arofylline (1 mg/kg) twice daily for four weeks; (B) prednisone (0.5 mg/kg) twice daily for the first week, once a day during the second week and every 48 hours for the remaining two weeks; (C) prednisone following the same protocol but at a dose of 0.25 mg/kg; or (D) arofylline (1 mg/kg) twice daily for four weeks plus prednisone (0.25 mg/kg) following the same protocol as in (B) and (C). The degree of pruritus and skin lesions and the side effects were evaluated and graded from 0 to 3 before and weekly during the treatments. In all cases there was a progressive clinical improvement in the clinical signs, with no statistical differences among the four treatments. However, many of the dogs treated with arofylline vomited and had adverse gastrointestinal signs.

[Non-aneurysmatic aortic dysphagia]

Esophageal compression by a vascular structure is a rare cause of dysphagia, the aberrant right subclavian artery being the most common congenital abnormality. Aortica dysphagia is usually observed in the elderly, especially in hypertensive women with cardiopathy and degenerative osteopathy. We report a 73-year-old woman with dysphagia, caused by a non-aneurysmatic aortic elongation, who presented progressive dysphagia, which ended in aphagia associated with heart failure. The diagnostic approach to these patients is discussed. The patient received cinitapride and, following treatment for heart failure, remains asymptomatic after a 3-year follow-up period, although manometric alterations persist.

Diagnosis of canine leishmaniasis by a polymerase chain reaction technique

A polymerase chain reaction (PCR) technique for the diagnosis of canine leishmaniasis on bone marrow samples was developed which amplified a 120 bp DNA fragment of the Leishmania kinetoplast DNA, common to all Leishmania species. Forty-five of 46 dogs in which leishmaniasis had been diagnosed were positive with the PCR technique, whereas none of 41 healthy dogs gave a positive result. Fifteen dogs with leishmaniasis that had been treated for six months with N-methylglucamine antimoniate and allopurinol were also investigated. Seven were positive, implying that they remained infected despite the resolution of their clinical signs.

Comparative study of histamine release from skin mast cells dispersed from atopic, ascaris-sensitive and healthy dogs

Atopic dermatitis results from the interaction between allergen and allergen-specific IgE bound to the mast cell surface receptors. This process triggers mast cell degranulation and accounts at least for early phase reaction. Furthermore, there is increasing in vitro and in vivo evidence that IgE has the ability to induce overexpression of the Fc epsilonRI receptor on the mast cell plasma membrane. In order to study the potential effect of an increase in serum IgE on mast cell activity, the histamine releasability of mature mast cells isolated from the skin of atopic, ascaris-sensitive and healthy dogs was analyzed. No histamine release was detected upon the immunological stimulation of cells that were not previously sensitized with atopic or ascaris-sensitive dog serum. However, when passively sensitized, skin mast cells were challenged with either Asc SI antigen or anti-IgE, the mast cell histamine release increased in a stimulus concentration-dependent manner. The amount of histamine released was significantly higher in response to anti-IgE than in response to Asc SI antigen. However. the difference in the percentage of mast cell histamine release between atopic (26.3+/-2.8%) and non-atopic (30.9+/-1.7%) dogs was not statistically significant, similar to what occurred when ascaris-sensitive (12.8+/-1.6%) and non-sensitive (13.2+/-1.7%) dogs were compared. Although these results could suggest that there is either little or no increase in the density of IgE receptors in atopic or ascaris-hypersensitive dogs versus controls, we strongly consider either the possibility that the digestion procedure might affect cell behaviour in vitro or that an underlying increase of receptors poorly affects the release of granule-stored mediators but influences mast cell activity in a different manner.

Comparative morphofunctional study of dispersed mature canine cutaneous mast cells and BR cells, a poorly differentiated mast cell line from a dog subcutaneous mastocytoma

The dog mastocytoma BR cell line provides us with a permanent source of canine mast cells, allowing a characterization of secretory mediators that exert important effects in canine allergic and nonallergic diseases and in physiological processes. We studied the ultrastructural characteristics and histamine releasing activity after immunological and non-immunological stimuli of the dog mastocytoma BR cell line, and compared the cell line to normal skin mast cells enzymatically isolated from healthy dogs. The histamine content of BR cells was 0.04 +/- 0.002 pg/cell, approximately 100-fold less than that found in canine skin mast cells. Non-immunologic stimuli induced similar concentration-dependent histamine release from skin mast cells and BR cells: 29.3 +/- 0.9% vs. 12.7 +/- 0.7% (calcium ionophore A23187), 23.3 +/- 0.7% vs. 18.8 +/- 0.7% (substance P) and 12.5 +/- 0.3% vs. 12.1 +/- 0.9% (compound 48/80), respectively. Immunologic stimulation, however, was only effective on canine skin mast cells, causing 30.9 +/- 1.7%, 27.7 +/- 0.6% and 12.2 +/- 0.9% histamine release in response to anti-canine IgE, concanavalin A, and antigen Asc S 1, respectively. The absence of functional IgE receptors in BR cells was confirmed by the lack of response to anti-IgE and antigen Asc S 1 following passive sensitization with dog atopic serum and dog antigen sensitized serum. We conclude that BR cells are able to release histamine after non-immunologic stimulation in a similar manner to canine skin mast cells, but that there are morphological and functional differences possibly due to different states of maturity or differentiation. For this reason the study of the highly homogeneous BR cells could offer insights into dog mast cell biology in contexts where freshly isolated cells cannot be used because of low purity and recovery.

CD26 expression and dipeptidyl peptidase IV activity in an aggressive hepatosplenic T-cell lymphoma

The transmembrane serine aminopeptidase dipeptidyl peptidase IV (DPP IV) (also known as CD26) participates in several immunological functions and has a binding affinity for several molecules, including collagen, which may be an integral mechanism for T cells to traverse endothelial barriers. Since CD26 is phenotypically expressed in certain T-cell malignancies, this study utilized a novel four-color cytofluorographic procedure to measure DPP IV enzymatic activity concurrently with the expression of other surface markers in an aggressive hepatosplenic T-cell lymphoma. Immunophenotypic analysis by flow cytometry revealed the tumor to be CD2+, CD3+, CD5-, CD7+, TcR-gamma/delta+, CD4-, CD8+/-, CD56+, and CD11c+. The CD26 molecule was also expressed, and DPP IV activity was present, with the maximal activity detectable after 10 min of incubation. These results represent the initial description of enzymatically active CD26 in a T-cell malignancy, and raise the possibility that this molecule may be a participant in the pathogenetic mechanisms utilized by the neoplastic cells.

[Collagenous colitis: presentation of 12 cases]

Collagenous colitis (CC) is a cause of chronic aqueous diarrhea with normal radiologic study and endoscopic appearance of the colonic mucosa. Histologically, it is defined by the presence of a thickened subepithelial collagenous band and inflammatory changes of the mucosa. The cause of CC is currently unknown, although several mechanisms have been proposed, such as an inflammatory, autoimmune, origin, disregulation in collagen synthesis, plasma vasculosis and a possible role of bacterial or drug toxins. The clinicopathological data of 12 patients (9 females and 3 males) with a mean age of 52.4 years diagnosed by histologic criteria are presented. Aqueous diarrhea was observed in all the patients with a mean number of 5.4 stools/day during a time period between 3 weeks and 10 years (mean, 14.7 months). In a 6 patients allergies and/or associated diseases, mainly rheumatologic diseases were found. Laboratory and endoscopic data were normal or unspecific, with colon biopsy being carried out in all the patients. Several treatments were tested with good response with sulphasalazine derivatives, corticoids, antibiotics, and mebeverine, with no solution to the diarrhea in 2 patients. A review of the literature is also provided.