Temporal and spatial heterogeneity in milk and immune-related gene expression during mammary gland involution in dairy cows.

The aim of this study was to investigate heterogeneity in tissue morphology, milk protein and immune-related gene expression, and apoptosis of epithelial cells in the lactating and involuting mammary glands of the dairy cow. Mammary tissue from different regions of the gland (alveolar, cisternal, and peripheral) was collected postmortem from nonpregnant, pasture-fed, Holstein-Friesian primiparous cows in mid-lactation that were killed at different time points postmilking: 0, 6, 12, 18, 24, 36, and 72 h (n = 6 per time point). The CSN1NS1 and LALBA mRNA was decreased in alveolar, cisternal, and peripheral tissue by 12 to 36 h postmilking. In contrast, lactoferrin (LF) and mammary serum amyloid A3 (M-SAA3) mRNA was increased in these regions by 36 to 72 h. During lactation, more variability was present in gene expression in alveolar tissue between cows and between quarters within a cow, than within quarters. Histological analysis indicated the alveolar tissue from lactating cows was mostly uniform in structure; however, in situ hybridization indicated that although most of the alveolar tissue expressed milk proteins, the level of expression varied within and between alveoli. This heterogeneity became more pronounced with involution and with increasing regions of alveoli expressing lactoferrin, indicating that alveoli enter involution asynchronously. The peripheral and cisternal tissue had more variability in gene expression between cows compared with the alveolar tissue. The M-SAA3 signal was more intense in the cisternal tissue and less intense than the peripheral compartment compared with LF particularly in the earlier time points. In addition, between cows within the later time points, differences were observed in tissue morphology, the levels of milk protein and immune-related gene expression, and phosphorylated signal transducer and activator of transcription (STAT) 5-P and STAT3-P proteins, and degree of apoptosis, indicating that involution of the mammary gland occurs at different rates between cows. Understanding the mechanisms initiating the process of involution of the mammary gland provides an opportunity for enhancing milk production of the dairy cow.

Cell survival signaling in the bovine mammary gland during the transition from lactation to involution.

In dairy cows, mammary gland involution, and thus a decline in milk production, occurs following peak lactation. To examine the cell signaling pathways regulating involution of the mammary gland, signal transducer and activator of transcription factors (STAT5 and 3), suppressors of cytokine signaling (SOCS1-3 and CIS), insulin-like growth factors (IGF1 and 2), and protein kinase B (Akt) were examined. Mammary involution was induced by termination of milking, and alveolar tissue was collected from 52 nonpregnant, primiparous, mid-lactation Holstein-Friesian cows killed at 0, 6, 12, 18, 24, 36, 72, and 192h postmilking. Qualitative immunohistochemistry showed that activated (phosphorylated) STAT5-P was localized in nuclei of mammary epithelial cells at the early time points, with detection levels decreasing by 24h postmilking. In contrast, STAT3-P was barely detectable at the early time points, with detection levels increasing following longer postmilking periods. This was supported by Western analysis, which showed a decline in STAT5 and STAT5-P protein levels by 24h postmilking, no change in STAT3 levels, and an increase in STAT3-P protein (barely detectable at the early time points) by 72h postmilking. Quantitative real-time reverse transcription PCR analysis showed SOCS1 and SOCS3 mRNA increased by 72h postmilking compared with 6h postmilking. The SOCS2 mRNA remained unchanged across the time series, whereas CIS decreased by 18h postmilking and remained lower compared with that at 6h postmilking until 72h postmilking. The IGF1 mRNA increased by 192h postmilking, whereas IGF2 mRNA decreased by 18h postmilking compared with 6h postmilking. The IGFBP5 mRNA and protein levels of Akt and Akt-P remained unchanged over the time series. These results show that reciprocal activation of STAT5 and STAT3 occurs at the onset of mammary gland involution in the bovine, albeit at a slower rate than in rodents. Mathematical modeling of the pathways indicated that activated STAT3 could block the STAT5 pathway by upregulating SOCS3. The regulation of IGF1-Akt signaling suggests that by 192h postmilking in dairy cows, the involution process is still in the reversible phase, with quiescent mammary epithelial cells not yet in the senescent phase.

An immunohistochemical study of the expression of the hypoxia markers Glut-1 and Ca-IX in canine sarcomas.

Tumor hypoxia has been associated with increased malignancy, likelihood of metastasis, and increased resistance to radiotherapy and chemotherapy in human medicine. Hypoxia-inducible factor-1 (HIF-1) is a key transcription factor that is induced by tumor hypoxia and regulates the pathways involved in cellular response and adaptation to the hostile tumor microenvironment. HIF-1 induces transcription of different proteins, including Ca-IX and Glut-1, which are considered endogenous markers of chronic hypoxia in solid tumors in humans. In this study, sections from 40 canine sarcomas (20 histiocytic sarcomas and 20 low-grade soft-tissue sarcomas) were immunostained for these markers. Expression of Glut-1 was scored based on percentage of positive staining cells (0 = <1%; 1 = 1%-50%; 2 = >50%) and intensity of cellular staining (1 = weak; 2 = strong); Ca-IX was scored based on percentage of positive cells (0 = <1%; 1 = 1%-30%; 2 = >30%). Intratumoral microvessel density was measured using CD31 to assess intratumoral neoangiogenesis. Histiocytic sarcomas showed statistically significant higher Glut-1 immunoreactivity and angiogenesis than did low-grade soft-tissue sarcomas. Intratumoral microvessel density in histiocytic sarcomas was positively associated with Glut-1 immunoreactivity score. These findings suggest a potential role of hypoxia in the biology of these tumors and may provide a base for investigation of the potential prognostic use of these markers in naturally occurring canine tumors.

The clinical presentation and histopathologic-immunohistochemical classification of histiocytic sarcomas in the Flat Coated Retriever.

The Flat Coated Retriever is a breed at risk of development of histiocytic sarcoma (HS), but in contrast to the disseminated form of disease recognized in the Bernese Mountain Dog, most reports of HS in Flat Coated Retrievers describe a localized lesion affecting the musculature or fascia of limbs. The purpose of this study was to review data and material received though an ongoing Flat Coated Retriever tumor survey to better define the presentation of HS in the breed and to determine the utility of subclassification of tumors arising at different sites by histology and immunohistologic phenotyping. Data on 180 dogs bearing HS-like tumors were available for review, which showed that although the majority (101 lesions, 57%) were primary limb lesions, 47 dogs (26%) had visceral, mainly splenic lesions with no peripheral primary tumor. A detailed histologic and immunohistologic review of 20 limb tumors and 20 splenic tumors showed that 2 distinct phenotypic subtypes could be identified: a histiocytic subtype, most prevalent in the splenic tumors, and a histiocytic-spindle-pleomorphic subtype, mainly seen in the limb tumors. Despite their variable morphology, all tumors expressed major histocompatibility complex class II and the leukocyte antigen CD18, but only those tumors in the spleen consistently expressed CD11d. The majority of tumors also contained a mild to moderate infiltrate of T lymphocytes.

Exogenous insulin treatment after hypofractionated radiotherapy in cats with diabetes mellitus and acromegaly.

BACKGROUND: The optimal treatment for feline acromegaly has yet to be established. Surgical and medical therapies are minimally effective although radiotherapy might have greater efficacy. The purpose of this study was to review the response and outcome of cats with acromegaly and insulin-resistant diabetes mellitus (DM) to radiotherapy. HYPOTHESES: That radiotherapy improves glycemic control in cats with acromegaly and that improved glycemic control is due to remission of clinical acromegaly; demonstrated by a fall in serum insulin-like growth factor-1 (IGF-1) concentrations. ANIMALS: Fourteen cats with naturally occurring acromegaly. METHODS: Retrospective case review; records of all cats treated for acromegaly with radiotherapy were reviewed from 1997 to 2008. Cats were selected on the basis of compatible clinical signs, laboratory features, and diagnostic imaging findings. Fourteen cats received radiotherapy, delivered in 10 fractions, 3 times a week to a total dose of 3,700 cGy. RESULTS: Thirteen of 14 cats had improved diabetic control after radiotherapy. These improvements were sustained for up to 60 months. DM progressed in 2 cats and 1 did not respond. Seven cats responded before the final treatment. Ten cats were euthanized, 1 as a consequence of radiotherapy. In 8 cats in which IGF-1 was measured after treatment, changes in its concentration did not reflect the clinical improvement in glycemic control. CONCLUSIONS AND CLINICAL IMPORTANCE: Radiotherapy represents an effective treatment for cats with insulin-resistant DM resulting from acromegaly. IGF-1 concentration after treatment does not provide a suitable method by which remission from either acromegaly or insulin-resistant DM may be assessed.

Significant advances in veterinary oncology - 60 years on.

The first edition of the Journal of Small Animal Practice published in February 1960, contained a paper entitled "Recent Treatments of Malignant Neoplasia" by Dr Larry Owen. Now we have reached the 60th anniversary of JSAP, that article provides a baseline from which to review subsequent advances in veterinary oncology, which now includes worldwide networks that have resulted in veterinary oncology becoming the multidisciplinary speciality that it is today. There certainly have been many advances in understanding of the pathology and epidemiology of animal cancers and in methods of diagnosis and treatment. However, the subject has become so large and diverse that not all aspects can be covered in detail here. It should also be acknowledged that there are still many gaps in knowledge in this field and that, because of a lack of randomised clinical trials, the evidence base for what is often regarded as "standard of care" is weak.

Geographic distribution and environmental risk factors of lymphoma in dogs under primary-care in the UK.

OBJECTIVES: To integrate external data sources with VetCompass postcode data to explore the spatial distribution and examine potential associations with environmental risk factors in dogs diagnosed with lymphoma at primary care veterinary practices. MATERIALS AND METHODS: Cases of lymphoma were identified from electronic patient records of 455,553 dogs under primary veterinary care during 2013 in the UK. Cases were defined as either laboratory-confirmed or non-laboratory-confirmed. Disease maps at the postcode-district level were used to define the geographic distribution of lymphoma incidence and spatial clustering was explored. Environmental risk factors from external data sources were transferred to a compatible format and logistic regression modelling was used to examine associations between environmental herbicide, fungicide and radon concentrations with lymphoma. RESULTS: From the denominator population of 455,553 dogs, 279 lymphoma cases (187 with laboratory confirmation and 93 without) were identified. Heterogeneous geographic variation was observed with weak evidence of clustering around London and the south-west of England. Herbicide and fungicide exposures were weakly associated with a diagnosis of lymphoma in the univariable analysis. After accounting for the age at diagnosis and breed in the multivariable analysis, herbicide exposure was associated with a diagnosis of lymphoma. CLINICAL SIGNIFICANCE: The heterogeneous distribution of lymphoma in UK dogs provides further evidence for geographic variation of lymphoma, perhaps in part associated with underlying environmental risk factors. The results suggest an association between environmental herbicide and canine lymphoma.

cDNA microarray analysis reveals that antioxidant and immune genes are upregulated during involution of the bovine mammary gland.

We have used cDNA microarray analysis to identify genes that play a role in bovine mammary involution. Involution was induced by termination of milking, and alveolar tissue was collected from 48 nonpregnant Friesian cows in mid lactation sacrificed at 0, 6, 12, 18, 24, 36, 72, and 192 h (n = 6/group) postmilking. The most highly upregulated genes were those associated with oxidative stress. Quantitative real-time reverse-transcription PCR analysis confirmed that mRNA expression of spermidine/spermine N(1)-acetyltransferase was increased by 24 h, superoxide dismutase 2 and metallothionein 1A by 36 h, and glutathione peroxidase by 72 h postmilking. The mRNA expression of the host defense proteins lactoferrin and lingual antimicrobial peptide were increased by 192 h postmilking. A dramatic increase in the protein expression of lactoferrin by 192 h postmilking was also detected by Western analysis. Decreased mRNA expression of the milk protein genes alpha(S1)-, beta-, and kappa-casein, and alpha-lactalbumin were early events in the process of involution occurring within 24 to 36 h postmilking, whereas beta-lactoglobulin mRNA was decreased by 192 h postmilking. Decreases in alpha-lactalbumin and beta-lactoglobulin protein levels in alveolar tissue occurred by 24 and 192 h postmilking, respectively, and the cell survival factors beta1-integrin and focal adhesion kinase were decreased by 72 and 192 h postmilking, respectively. The results demonstrate that in the bovine mammary gland, decreased milk protein gene expression and cell survival signaling are associated with multiple protective responses to oxidative stress that occur before the induction of immune responses and mammary epithelial cell apoptosis during involution.

Photodynamic therapy of superficial nasal planum squamous cell carcinomas in cats: 55 cases.

BACKGROUND: Squamous cell carcinomas (SCCs) are common skin tumors in cats. We investigated photodynamic therapy (PDT) using the photosensitizing agent 5-aminolaevulinic acid (5-ALA) topically and a high-intensity red light source. HYPOTHESIS: PDT is a safe and effective treatment for feline SCCs. ANIMALS: Fifty-five client-owned cats with superficial nasal planum SCCs. METHODS: Prospective, uncontrolled clinical trial. PDT was performed using topical 5-ALA and light of peak wavelength 635 nm. Adverse effects, response, and tumor control were evaluated. RESULTS: 53/55 (96%) cats responded to therapy, and there was a complete response in 47/55 (85%). Six cats (11%) had a partial response. Of the 47 cats with complete response to a single treatment, 24 recurred (51%), with a median time to recurrence of 157 days (95% confidence interval, 109-205 days). Repeat PDT was performed in 22 cats, and at a median follow-up of 1,146 days, 23 (45%) cats were alive and disease free, 17 (33%) had to be euthanized due to tumor recurrence, and 11 (22%) were euthanized for other reasons. Only transient mild local adverse effects were observed after treatment. CONCLUSIONS AND CLINICAL IMPORTANCE: PDT using 5-ALA and a red light source was safe, well tolerated, and effective in the treatment of superficial nasal planum SCCs of cats and offers an alternative to conventional therapy. Although initial response rates were high, this treatment did not lead to a durable remission or cure in all cases.

Retrospective review of 50 canine nasal tumours evaluated by low-field magnetic resonance imaging.

OBJECTIVES: Low-field magnetic resonance imaging machines are being used more often in veterinary practice for the investigation of sinonasal disease. The aim of this retrospective study was to describe and characterise the low-field magnetic resonance imaging features of nasal tumours in dogs. METHODS: The Queen's Veterinary School Hospital magnetic resonance imaging database (2001-2005) was searched for dogs with a magnetic resonance imaging diagnosis of a nasal tumour. Fifty cases with histological diagnosis of nasal tumour were found. The appearance and extent of the nasal tumour as well as the involvement of adjacent anatomic structures were examined against a checklist. RESULTS: The most common magnetic resonance imaging findings were as follows. (1) Soft tissue mass replacing the destroyed nasal conchae and/or ethmoturbinates (98 per cent of cases). (2) Nasal septum destruction (68 per cent of cases). (3) Retained secretions with or without mass caudally in frontal sinuses (62 per cent of cases). (4) Nasal/frontal bone destruction (52 per cent of cases). Low-field magnetic resonance imaging allowed differentiation of tumour tissue from retained secretions or necrotic tissue. Magnetic resonance imaging was invaluable in assessing the extension of the tumour into the maxillary recesses, caudal recesses, nasopharynx, adjacent bones and cranial cavity. The tumour often extended caudally into the frontal sinuses, nasopharynx and perhaps most importantly into the caudal recesses. Tumour extension into the cranial cavity was not common (16 per cent), and only three of these cases showed neurological signs. However, 54 per cent of cases showed focal meningeal (dural) hyperintensity, although the significance of this is unclear. A significant difference (P<0.05) in tumour signal intensity between the sarcomas and carcinomas was found. CLINICAL SIGNIFICANCE: The use of a low-field magnetic resonance imaging technique is excellent for the diagnosis and determination of extent of sinonasal tumours.

The future of radiotherapy in small animals - should the fractions be coarse or fine?

Radiation therapy has been used to treat animal cancers for more than 100 years. Clinical experiences and experimental results have been widely published and provide a basis for the recognition of radiation therapy as an integral component of multimodal cancer management in veterinary oncology. As the expectations of pet owners and the demand for treatment of companion animals with cancer have increased, veterinary oncology itself has undergone dramatic advances in the past several decades both in terms of improved diagnostics and treatments, including increased accessibility of radiation therapy. Synchronous with development of the specialism of veterinary radiation oncology, confusion and controversy have arisen with regard to distinguishing between different types of radiotherapy and methods of treatment delivery. Importantly, the confusion extends beyond semantics, and includes opinionated debate about defining which forms of therapy (if any at all) are optimal for a given patient. This exemplifies how, despite marks of maturity including age and a robust publication history, the field of veterinary radiation oncology is in some ways still in its infancy. The purpose of this article is to review the evidence base for daily (fine) fractionation versus weekly (coarse) hypofractionation in veterinary oncology, using selected tumour types as examples.

Advances in the diagnosis and management of cutaneous mast cell tumours in dogs.

Mast cell tumours are one of the most common tumours of the canine skin and have a reputation for being difficult to manage because of their variable clinical presentation, behaviour and response to treatment. This review of recent literature on canine mast cell tumours suggests that the majority of such tumours may not be as bad as their reputation suggests. Most grade I and grade II tumours can be managed successfully by good surgery. Recent literature also calls into question the utility of clinical staging systems and the value of assessing surgical margins for prognosis and highlights the paucity of well-conducted, case-controlled clinical trials in assessing the efficacy of medical management of high-risk tumours. In terms of more basic research, recent studies have implicated the stem cell factor receptor KIT as having a role in the aetiology of canine mast cell tumours and there appears to be an association between c-kit mutation and higher grade of tumour. This may offer a possible target for new therapeutic approaches.

Glycolysis inhibition improves photodynamic therapy response rates for equine sarcoids.

Photodynamic therapy (PDT) holds great promise in treating veterinary and human dermatological neoplasms, including equine sarcoids, but is currently hindered by the amount of photosensitiser and light that can be delivered to lesions thicker than around 2 mm, and by the intrinsic antioxidant defences of tumour cells. We have developed a new PDT technique that combines an efficient transdermal penetration enhancer solution, for topical delivery of 5-aminolevulinic acid (ALA) photosensitiser, with acute topical post-PDT application of the glycolysis inhibitor lonidamine. We show that the new PDT combination treatment selectively kills sarcoid cells in vitro, with repeated rounds of treatment increasing sarcoid sensitisation to PDT. In vivo, ALA PDT followed by 600 µM lonidamine substantially improves treatment outcomes for occult, verrucous, nodular and fibroblastic sarcoids after 1 month (93% treatment response in 27 sarcoids), compared with PDT using only ALA (14% treatment response in 7 sarcoids).

A retrospective review of treatment and response of high-risk mast cell tumours in dogs.

This retrospective case series evaluates survival outcome of 94 dogs with high metastatic risk mast cell tumours (MCT). Patients were treated with a cytotoxic chemotherapy protocol or the tyrosine kinase inhibitor masitinib, in the presence of gross disease or as an adjunct to surgical resection of the primary tumour. In patients presenting with metastatic disease, surgical resection of the primary tumour with adjunctive therapy with any chemotherapy incurred a significant survival advantage [median survival time (MST): 278 days] compared to patients receiving chemotherapy without surgical excision of the primary tumour (MST: 91 days, P < 0.0001). Patients with a surgically excised Patnaik grade II tumour and high Ki-67 in the absence of metastatic disease treated with vinblastine and prednisolone showed a significantly longer survival (MST: 1946 days) than those treated with masitinib (MST: 369 days, P = 0.0037). Further prospective case-controlled clinical trials of high-risk MCTs are required to make precise evidence-based treatment decisions for individual patients.

Pharmacokinetic and pharmacodynamic study of the combination of docetaxel and topotecan in patients with solid tumors.

PURPOSE: The sequence in which chemotherapeutic agents are administered can alter their pharmacokinetics, therapeutic effect, and toxicity. We evaluated the pharmacokinetics and pharmacodynamics of docetaxel and topotecan when coadministered on two different sequences of administration. PATIENTS AND METHODS: On cycle 1, docetaxel was administered as a 1-hour infusion at 60 mg/m(2) without filgrastim and at 60, 70, and 80 mg/m(2) with filgrastim on day 1, and topotecan was administered at 0.75 mg/m(2) as a 0.5-hour infusion on days 1 to 4. On cycle 2, topotecan was administered on days 1 to 4, and docetaxel was administered on day 4. Cycles were repeated every 21 days. Blood samples for high-performance liquid chromatography measurement of docetaxel (CL(DOC)) and topotecan (CL(TPT)) total clearance were obtained on day 1 of cycle 1 and day 4 of cycle 2. CL(DOC) and CL(TPT) were calculated using compartmental methods. RESULTS: Mean +/- SD CL(DOC) in cycles 1 and 2 were 75.9 +/- 79.6 L/h/m(2) and 29.2 +/- 17.3 L/h/m(2), respectively (P: <.046). Mean +/- SD CL(TPT) in cycles 1 and 2 were 8.5 +/- 4.4 L/h/m(2) and 9.3 +/- 3.4 L/h/m(2), respectively (P: >. 05). Mean +/- SD neutrophil nadir in cycles 1 and 2 were 4,857 +/- 6, 738/microL and 2,808 +/- 4,518/microL, respectively (P: =.02). CONCLUSION: Administration of topotecan on days 1 to 4 and docetaxel on day 4 resulted in an approximately 50% decrease in docetaxel clearance and was associated with increased neutropenia.

Plasma pharmacokinetics and tissue distribution in CD2F1 mice of Pc4 (NSC 676418), a silicone phthalocyanine photodynamic sensitizing agent.

PURPOSE: Pc4 is a silicone phthalocyanine photosensitizing agent that is entering clinical trials. Studies were undertaken in mice to develop a suitable formulation and analytical methodology for use in pharmacokinetic studies and to define the plasma pharmacokinetics, tissue distribution, and urinary excretion of Pc4 after i.v. delivery. METHODS: An HPLC method suitable for separation and quantification of Pc4 was developed and validated for use in mouse plasma, tissues, and urine. The stability of Pc4 was characterized in a variety of formulations as well as in mouse plasma. Before pursuing pharmacokinetic studies, preliminary toxicity studies were undertaken. These studies utilized Pc4 formulated in diluent 12:0. 154 M NaCl (1:3, v:v). Pharmacokinetic studies involved Pc4 doses of 40 mg/kg, 10 mg/kg and 2 mg/kg administered as i.v. boluses to female, CD2F1 mice. Doses of 40 mg/kg, 10 mg/kg, and 2 mg/kg were studied with drug formulated in diluent 12:0.154 M NaCl (1:3, v:v). Doses of 10 mg/kg and 2 mg/kg were also studied with drug formulated in a vehicle consisting of polyethylene glycol:Tween 80:0. 01 M sodium phosphate buffer, pH 7.0 (40:0.2:59.8, v:v:v). Compartmental and non-compartmental analyses were applied to the plasma concentration-versus-time data. Concentrations of Pc4 were also determined in a variety of tissues, including brain, lung, liver, kidney, skeletal muscle, skin, heart, spleen, and abdominal fat. Urine was collected from animals treated with each of the doses of Pc4 mentioned above, and daily, as well as cumulative drug excretion was calculated until 168 h after treatment. RESULTS: At a dose of 80 mg/kg, two of five male and two of five female mice were dead by 24 h after injection. Pathologic examination revealed gross findings of blue discoloration affecting many tissues, with lungs that were grossly hemorrhagic and very blue-black. Microscopic examination of the lungs revealed mild acute interstitial pneumonia, with perivascular edema and inflammation, and a detectable margination of neutrophils around larger pulmonary blood vessels. Animals sacrificed 14 days after treatment showed mild granulomatous pneumonia, characterized by clusters of multi-nucleated giant cells, with fewer macrophages and neutrophils. The giant cells frequently contained phagocytized particles, which were clear and relatively fusiform. All mice treated with 40 mg/kg or 20 mg/kg survived and returned to pretreatment weight during the 14 days after treatment. Intravenous bolus delivery of Pc4, at a dose of 40 mg/kg, produced "peak" plasma Pc4 concentrations between 7.81 and 8.92 microg/ml in mice killed at 5 min after injection (the earliest time studied after drug delivery). Sequential reduction of the Pc4 dose to 10 mg/kg in diluent 12:0.154 M NaCl (1:3, v:v), 10 mg/kg in polyethylene glycol:Tween 80:sodium phosphate buffer (40:0.2:59.8, v:v:v), 2 mg/kg in diluent 12:0.154 M NaCl (1:3, v:v), and, finally, 2 mg/kg in polyethylene glycol:Tween 80:sodium phosphate buffer (40:0.2:59.8, v:v:v) resulted in "peak" plasma Pc4 concentrations between 2.07 and 3.24, 0.68 and 0.98 microg/ml, and 0.29 and 0.41 microg/ml, respectively. Pc4 persisted in plasma for prolonged periods of time (72-168 h). Non-compartmental analysis of plasma Pc4 concentration-versus-time data showed an increase in area under the plasma Pc4 concentration-versus-time curve (AUC) when the dose of Pc4 increased from 2 mg/kg to 40 mg/kg. Across the 20-fold range of doses studied, total body clearance (CL(tb)) varied from 376 to 1106 ml h(-1) kg(-1). Compartmental modeling of plasma Pc4 concentration versus time data showed the data to be fit best by a two-compartment, open, linear model. Minimal amounts of Pc4 were detected in the urine of mice. After i.v. bolus delivery to mice, Pc4 distributed rapidly to all tissues and persisted in most tissues for the duration of each pharmacokinetic study. Tissue exposure, as measured by AUC, increased in a dose-dependent fash

Generation of blood-derived dendritic cells in dogs with oral malignant melanoma.

Advances in treatment of human melanoma indicate that immunotherapy, particularly dendritic cell (DC) immunization, may prove useful. The aim of this study was to investigate whether blood-derived DCs could be generated from canine melanoma patients. Peripheral blood mononuclear cells were isolated from three such dogs and cultured with recombinant canine granulocyte-macrophage colony stimulating factor (GM-CSF), canine interleukin 4 and human Flt3-ligand for 7 days. The resulting cells demonstrated a typical dendritic morphology, and were enriched for cells expressing CD1a, CD11c and MHC II by flow cytometric analysis. Thus, canine blood-derived DCs can be generated in vitro and DC immunization should be feasible in dogs.

Long-term outcome of eight cats with non-lymphoproliferative nasal tumours treated by megavoltage radiotherapy.

A retrospective study was undertaken to evaluate the long term survival of eight cats with non-lymphoproliferative nasal tumours treated by megavoltage radiotherapy alone. Adenocarcinoma was the most commonly diagnosed tumour. Megavoltage radiotherapy was given to eight cats in 4-6 fractions of 4-8 Gys over a 16 to 28 day period. Seven cats completed the radiotherapy schedule and only two cases developed mild acute radiotherapy side effects. Median survival time after the completion of the radiotherapy course as calculated by Kaplan-Meier survival analysis was 382 days. The 1 year survival rate was 63%. All cats were euthanased because of either a poor response to radiotherapy or recurrence of the nasal tumour. This study demonstrates that a coarse fractionation regime of megavoltage radiotherapy can provide effective long-term palliative treatment for feline nasal tumours. The coarse fractionation schedule has the advantages of requiring only four to six treatments.

Radiotherapy of oral malignant melanomas in dogs.

OBJECTIVE: To evaluate response to radiotherapy in dogs with oral malignant melanomas. DESIGN: Clinical trial. ANIMALS: 36 dogs with histologically confirmed oral malignant melanomas. PROCEDURE: The prescribed radiation dose was 36 Gy given in 4 fractions of 9 Gy at 7-day intervals. The primary radiation source was a linear accelerator. RESULTS: In 25 of 36 dogs, complete remission was achieved, and in 9 dogs, partial remission was achieved. Recurrence of the primary tumor was the cause of euthanasia of 4 dogs. Twenty-one dogs were euthanatized because of metastasis. CLINICAL IMPLICATIONS: Radiotherapy was an effective palliative treatment for the primary tumor in dogs with oral malignant melanomas. However, rapid development of metastatic disease remained a major challenge.

Use of tamoxifen in the control of canine mammary neoplasia.

Ninety-three bitches which had undergone mammary tumour surgery were entered into a clinical trial to examine the effects of ovariohysterectomy (spaying) at the time of mammary surgery and the use of the drug tamoxifen in preventing the recurrence of the tumour and/or the development of new mammary tumours. Twenty-three of the bitches which had been spayed were allocated tamoxifen but only 18 of them complied with the treatment and in nine of these the treatment was stopped owing to side effects (mostly oestrogenic). Too few animals were studied to draw conclusions about the possible preventative effects of tamoxifen on mammary neoplasia, but the high percentage of bitches affected by oestrogen-like side effects may reduce the compliance of owners and prevent tamoxifen being widely used in dogs.