Pharmacokinetics and pharmacodynamics of A77 1726 and leflunomide in domestic cats.

The pharmacokinetics and pharmacodynamics of A77 1726 and leflunomide after intravenous (i.v.) and oral (p.o.) administration were evaluated in adult cats. Three treatments were administered: a single i.v. dose of A77 1726 (4 mg/kg), a single oral dose of leflunomide (4 mg/kg), and multiple oral doses of leflunomide (2 mg/kg). Mean pharmacokinetic parameter values after a single i.v. dose of A77 1726 were distribution (A) and elimination (B) intercepts (15.2 µg/mL and 34.5 µg/mL, respectively), distribution and elimination half-lives (1.5 and 71.8 h, respectively), area under the curve (AUC(0 → ∞); 3723 µg*h/mL), mean residence time (MRT; 93 h), clearance (Cl(obs); 1.1 mL/kg/h), and volume of distribution at steady state (Vd(ss); 97 mL/kg). Mean pharmacokinetic parameter values after a single oral dose of leflunomide were absorption and elimination rate constants (0.3 1/h and 0.01 1/h, respectively), absorption and elimination half-lives (2.3 and 59.1 h, respectively), AUC(0 → ∞) (3966 µg*h/mL), and maximum observed plasma concentration (C(max); 38 µg/mL). The bioavailability after a single oral dose of leflunomide was 100%. The mean ± SD A77 1726 concentration that inhibited 50% lymphocytes (EC(50) ) was 16 ± 13.5 µg/mL. The mean ± SD maximum A77 1726 concentration (EC(max)) was 61.0 ± 23.9 µg/mL.

Histopathologic Changes, Ultrastructure, and Molecular Characterization of an Adenovirus in a Sun Conure (Aratinga solstitialis).

In this case report, we describe the pathologic changes and the ultrastructural and molecular characteristics of an adenovirus in a sun conure (Aratinga solstitialis) that presented with a history of sudden death. On histologic examination, there was multifocal hepatic and splenic necrosis. Within some hepatocytes and unidentified cells in the spleen, renal interstitial fibroblasts, and ovarian stroma were intranuclear amphophilic inclusion bodies. Electron microscopy of affected tissue showed intranuclear icosahedral viral particles with an inner capsid (29.2-33.8 nm in diameter) and an outer capsid (70.2-71.7 nm in diameter). Next-generation sequencing and BLAST analysis of complementary DNA synthesized from RNA extracted from formalin-fixed tissues showed an adenovirus, designated sun conure adenovirus (SCAdv). A DNA in situ hybridization (ISH) probe, constructed from the SCAdv and similar sequences from GenBank, was also positive in the intranuclear inclusion bodies, whereas standard ISH for psittacine adenovirus 1 was negative. These results show that ancillary diagnostic testing, such as next-generation sequencing, even using formalin-fixed, paraffin-embedded tissues, along with ISH, can be useful in identifying additional, unknown viruses that show similar pathology to commonly known viruses but do not show up as positive on routine diagnostic tests.

Reporte de caso- Cambios histopatológicos, ultraestructura y caracterización molecular de un adenovirus en una cotorra solar (Aratinga solstitialis). En este reporte de caso, se describen los cambios patológicos y las características ultraestructurales y moleculares de un adenovirus en una cotorra solar (Aratinga solstitialis) que se presentó con un historial de muerte súbita. En el examen histológico, hubo necrosis hepática y esplénica multifocal. Dentro de algunos hepatocitos y células no identificadas en el bazo, los fibroblastos intersticiales renales y en el estroma ovárico se encontraron cuerpos de inclusión anfofílicos intranucleares. La microscopía electrónica del tejido afectado mostró partículas víricas intranucleares icosaédricas con una cápside interna (de 29.2 a 33.8 nm de diámetro) y una cápside externa (de 70.2 a 71.7 nm de diámetro). Mediante el análisis de secuenciación de segunda generación y por la Herramienta de Búsqueda de Alineaciones Local Básica (con siglas en inglés BLAST) del ADN complementario sintetizado a partir de ARN extraído de tejidos fijados con formalina mostraron un adenovirus, denominado adenovirus de cotorra solar (SCAdv). Se construyó una sonda de ADN para hibridación in situ (ISH), a partir de la secuencia del virus SCAdv y de secuencias similares de GenBank, que generó reacción positiva en los cuerpos de inclusión intranucleares, mientras que la hibridación in situ estándar para el adenovirus I de psitácidos fue negativa. Estos resultados muestran que las pruebas de diagnóstico complementarias, como la secuenciación de segunda generación, utilizando tejidos fijados con formalina e incluidos en parafina junto con la hibridación in situ pueden ser útiles para identificar virus adicionales desconocidos que muestran una patología similar a los virus comúnmente conocidos, pero que no se detectan con las pruebas diagnósticas de rutina.

Spontaneous haemorrhage from a left gastric artery aneurysm as a cause of acute abdominal pain.

Visceral artery aneurysms are rare, with a reported incidence of less than 2% in the general population. 1,2 Aneurysms of the left gastric artery are particularly uncommon, accounting for 4% of all visceral aneurysms. 3,4 Although the majority are discovered incidentally and can be managed conservatively, prompt treatment of those ruptured or at risk of rupture is crucial to reduce the associated morbidity. Increasing awareness of visceral artery aneurysms as a cause of spontaneous intraperitoneal haemorrhage will improve early recognition and impact on survival. We present a rare case of spontaneous rupture of a left gastric artery aneurysm.

Single photon emission computed tomography in planning unicompartmental knee arthroplasty. A prospective study examining the association between scan findings and intraoperative assessment of osteoarthritis.

The aim of this study was to determine the relationship between preoperative single photon emission computed tomography (SPECT) scan findings and intraoperative assessments of knee osteoarthritis (OA) in patients undergoing tibiofemoral unicompartmental knee arthroplasty (UKA). Fifty knees in 46 patients undergoing UKA were investigated preoperatively with a SPECT scan to confirm unicompartmental disease. There were 38 men and 12 women in the cohort with an average age of 63 years (range 44-78). The SPECT scan uptake in each compartment of the knee was graded by a single radiologist and these findings were compared with intraoperative assessments of OA (size and grade of lesion), made by two experienced surgeons, blinded to the scan findings. Significant association was demonstrated between scan findings and OA in all compartments of the knee (p<0.05), and this was strongest in the medial compartment and weakest in the patellofemoral compartment and lateral tibial plateau. We conclude that SPECT scan is a useful imaging modality in the planning of medial tibiofemoral UKA to confirm unicompartmental disease. The lower degree of association between scan findings and OA encountered in the patellofemoral compartments and lateral tibial plateau indicates that greater vigilance should be exercised in the intraoperative assessment of these areas.

Haemoglobin levels following unicompartmental knee arthroplasty: influence of transfusion practice and surgical approach.

A retrospective review was undertaken of preoperative and day 3 postoperative haemoglobin (Hb) levels in all unicompartmental knee arthroplasty (UKA) procedures performed by a single surgeon. Sixty-six UKAs were performed using the same prosthesis through an open approach with patella eversion. This group was compared with 212 UKAs performed using a minimally invasive approach without patella eversion, with an implant and instrumentation specifically devised for this approach. Both groups were well matched for patient demographics, surgical and anaesthetic techniques, thromboprophylaxis, and postoperative regimes. All patients received transfusions with pre-donated blood, except the unilateral minimally invasive approach group. An analysis of covariance was undertaken to examine the influence of the surgical approach and whether surgery was unilateral or bilateral, taking into account preoperative Hb levels and units of blood transfused. The average fall in Hb following UKA, adjusted for other variables, was 2.73 g/dl with an open approach compared to 1.82 g/dl with a minimally invasive approach. This difference was significant (p=0.0044). The average postoperative Hb in the minimally invasive group was 12.05 g/dl (range, 8.8 to 15.8 g/dl). Patients undergoing unilateral minimally invasive UKA are unlikely to develop symptomatic anaemia and should not be required to predonate blood or undergo transfusion.

Rapamycin inhibits arterial intimal thickening caused by both alloimmune and mechanical injury. Its effect on cellular, growth factor, and cytokine response in injured vessels.

The effect of rapamycin (RPM) on the extent of arterial intimal thickening was determined in rat recipients of orthotopic femoral artery allografts or in rats that had undergone balloon catheter injury to carotid arteries. In untreated rats, neointima comprised approximately 50% of the arterial wall area in both models. Although treatment of allograft recipients for 40 days with 1.5 mg/kg/day RPM was ineffective, a dose of 6 mg/kg/day (days 0-7) followed by 3 mg/kg/day (days 8-39) reduced intimal thickening by 98% (P < 0.0001). The higher RPM dose reduced T cell and macrophage infiltration significantly and decreased the expression of IL-2 receptor, class II Ag, and mRNAs for growth factors and cytokines. Treatment with 1.5 mg/kg/day RPM (days 0-13) after balloon-catheter injury reduced intimal thickening by 45% (P = 0.0254) and substantially decreased macrophage infiltration and expression of class II Ag in the adventitia. Within the neointima, however, mRNAs for platelet-derived growth factor-alpha, basic fibroblast growth factor, and transforming growth factor-beta were still expressed. In summary, we have shown that RPM inhibits not only the vascular response to injury caused by allograft rejection, but also the response to balloon catheter injury. This new information is important to our understanding of: (1) the fundamental processes responsible for intimal thickening regardless of the cause of vascular injury, (2) mechanisms of action of RPM that explain its effects on the response to very different types of vascular injury, and (3) the potentially diverse therapeutic applications of drugs, like RPM, that inhibit the actions of both immune and nonimmune cytokines and growth factors.

Effects of leflunomide and cyclosporine on myocutaneous allograft survival in the rat.

The immunosuppressive effects of leflunomide and cyclosporine were evaluated in a rat neurovascularized myocutaneous allograft model. Inbred Brown-Norway and Lewis rats were served as donors and recipients, respectively. All recipients were observed for 60 days or until allograft rejection occurred. All isograft controls (Lewis to Lewis, n=6) survived uneventfully. All control allografts (n=6) were rejected within 6 days. Allograft recipients (n=6) administered leflunomide (10 mg/kg/24 hr) rejected their allografts in 28.50+/-6.12 days, and allograft recipients (n=6), administered cyclosporine (5 mg/kg/24 hr) rejected their allografts in 24.33+/-10.48 days. When allograft recipients were administered a combination of leflunomide and cyclosporine (10 mg/kg/24 hr and 5 mg/kg/24 hr, respectively), all allografts survived to 60 days with only partial rejection of the skin of one graft. The neuromuscular function of the allografts of the rats receiving combination therapy was comparable to that of the isografts. The combination of leflunomide and cyclosporine controlled myocutaneous allorejection despite a strong immunological challenge.

Fluvastatin in combination with rad significantly reduces graft vascular disease in rat cardiac allografts.

BACKGROUND: RAD is a potent immunosuppressive agent that has been shown to be effective in preventing acute and chronic allograft rejection in animal models. The HMGCoA reductase inhibitors have been found to reduce the incidence of graft vascular disease (GVD) in heart transplant patients and in animal models. This study was designed to investigate the effects of fluvastatin or pravastatin in a rodent model of GVD produced using low doses of RAD to prevent acute rejection. METHODS: Hearts from Fisher 344 rats were heterotopically transplanted to Lewis rat recipients. RAD was administered orally at 0.5 mg/kg per day for days 0 to 14 and then 0.25 mg/kg per day for an additional 85 days to prevent acute rejection but allow for the development of GVD. Pravastatin (20 mg/kg per day) or fluvastatin (2 or 6 mg/kg per day) was added to the RAD treatment. At the end of a 100-day treatment period, the hearts were harvested for morphometric and histopathologic examinations. RESULTS: Rats treated with fluvastatin, at either dose, had a significant (P< or =0.0239) decrease in coronary arterial intimal thickening (GVD) of approximately 43%. Rats treated with pravastatin had a 22% reduction in GVD that did not reach statistical significance. Treatment with fluvastatin, but not pravastatin, decreased the degree of endomyocardial mononuclear cell infiltration seen with RAD administered alone. CONCLUSIONS: Fluvastatin significantly decreased GVD in a rat model produced using low-dose RAD immunosuppression. To a lesser extent, pravastatin also decreased GVD in this model. These data lend further support for the study of fluvastatin, pravastatin, and other HMG-CoA reductase inhibitors for the prevention of GVD in cardiac transplant patients.

Pathologic studies of acute rejection of mismatched feline musculocutaneous flaps. Effect of cyclosporine and prednisolone.

The gracilis musculocutaneous flap was developed as an allograft model to study acute rejection and immunosuppression in the cat. Twelve adult cats received a MLC incompatible flap. Six of the cats received cyclosporine oral solution and prednisolone (0.5 mg/kg/24 hr) for 100 days and six cats were not treated. Trough whole-blood levels of cyclosporine in the treatment group were maintained at approximately 750 ng/ml for 70 days, then 500 ng/ml for the remaining 30 days. Three flaps failed due to technical problems; 5 flaps were studied in the treatment group and 4 in the untreated group. All 5 flaps in the treatment group survived the 100 day treatment period and were rejected 30 +/- 26 days following cessation of treatment. Prior to discontinuation of treatment, with the exception of one cat, inflammatory changes associated with rejection were not observed in biopsy specimen. The flaps in the untreated group survived 13 +/- 1.5 days. Histopathologic examination of the flaps revealed little difference in the appearance of acute rejection and rejection after cessation of therapy. The most prominent lesion was a vasculitis with extensive perivascular lymphohistocytic inflammation. The lymphoid infiltrates consisted predominantly of T cells of both major classes (CD4 and CD8). Full-thickness epidermal necrosis and subsequent bacterial invasion followed vascular compromise.

Mizoribine serum levels associated with enterotoxicity in the dog.

To prevent or minimize mizoribine enterotoxicity in organ transplant recipients and to differentiate mizoribine enterotoxicity from other causes of enteritis, serum levels of mizoribine that produced subclinical and clinical signs of enterotoxicity were determined in the dog. When mizoribine was administered orally at 12-hr intervals, half the dogs studied showed clinical evidence of gastrointestinal disturbances (vomiting, diarrhea, and anorexia) without histopathologic signs of enterotoxicity. Using a 24-hr oral-dose schedule, clinical signs of gastrointestinal disturbances and histopathologic evidence (mucosal degeneration, crypt degeneration, and necrosis) of enterotoxicity were encountered when the mean 12-hr mizoribine serum level was 0.97 +/- 0.4 microgram/ml or greater. Histopathologic signs of enterotoxicity with repeated positive fecal occult blood assays and without clinical signs of gastrointestinal disturbances occurred when the mean 12-hr serum level was 0.53 +/- 0.17 microgram/ml or greater. Oral administration of cyclosporine did not exacerbate mizoribine enterotoxicity in the dog when administered with mizoribine at a dose that produced histopathologic signs of enterotoxicity.

Effects of combination cyclosporine/mizoribine immunosuppression on canine renal allograft recipients.

Heterotopic renal allografts following bilateral nephrectomies were placed in 21 healthy mongrel dogs. One group of 11 dogs received cyclosporine (5 mg/kg/24 hr, orally), and 1 group of 10 dogs received cyclosporine and mizoribine (5 mg/kg and 3 mg/kg/24 hr, orally). Body weights, blood cell counts, serum chemistry profiles, serum electrolyte levels, urinalysis with cytology and culture, lymphocyte stimulation assays, immunoglobulin levels, whole blood levels of cyclosporine, and serum levels of mizoribine were followed. At the end of each survival period, necropsy and histopathologic examinations were performed. The mean survival time for the cyclosporine group was 12.8 +/- 7 days. The mean survival time for the cyclosporine/mizoribine group was 33.6 +/- 16.4 days, significantly longer (P = .0006) than the cyclosporine group. Death in the cyclosporine/mizoribine group was attributed to the combined effects of renal allograft rejection and development of a mizoribine-dependent enteritis. Serum levels of mizoribine were greater in the last half of the survival period due to compromised renal excretion of the drug. There were no complications due to infection, myelosuppression, or hepatotoxicity. Combination cyclosporine/mizoribine immunosuppression enhanced canine renal allograft survival in this study. Monitoring serum concentrations of mizoribine is imperative to determine toxic (enteritis) levels. Availability of an intravenous form of mizoribine would facilitate immunoregulation during periods of variable intestinal absorption or renal excretion.

Treatment with rapamycin and mycophenolic acid reduces arterial intimal thickening produced by mechanical injury and allows endothelial replacement.

Rapamycin (RPM) and mycophenolic acid (MPA) inhibit immune responses by antagonizing IL-stimulated lymphocyte activation. These 2 drugs, used alone or preferably in combination, also significantly reduced the response of vascular cells to balloon-catheter arterial injury in rats. When rats were treated for 2 weeks with both drugs starting the day of injury, intimal thickening was significantly reduced (P < 0.001) 14 days after injury; however, by 44 days after injury, intimal thickening had progressed to the extent measured in arteries of untreated control rats. When RPM and MPA were administered for 3 days before and 13 days after injury, arterial intimal thickening was significantly (P = 0.024) reduced and endothelium had regrown in vessels analyzed 44 days after injury. Compared with initiation of treatment on the day of injury, starting the administration of RPM plus MPA before injury appears to limit the activation of cells or actions of factors responsible for the progression of intimal thickening that occurred after the administration of the drugs was terminated. RPM and MPA prevented the development of arterial intimal thickening in a model not dependent upon a rejection response. This direct antiproliferative action on smooth muscle cells by RPM and MPA, in vivo, may prevent the development of arterial intimal thickening associated with chronic rejection.

Combination leflunomide and cyclosporine prevents rejection of functional whole limb allografts in the rat.

Whole rear limbs were transplanted from Brown Norway or Lewis rat donors to Lewis rat recipients (n=6 per group). One group of allograft recipients was treated with leflunomide (10 mg/kg/24 hr/orally) and cyclosporine (5 mg/kg24 hr/orally) starting 2 days before to surgery. Treatment continued for 60 days or until graft rejection. Untreated allografts were rejected over 6-8 days. After isograft transplantation, weight bearing began by day 17-25 after surgery. Sensory function was restored by 50 days after surgery. All allografts in the drug-treated group survived the 60-day period; survival in this group was significantly longer (P=0.0001) than the untreated controls. Weight bearing began by day 30, but was incomplete in two rats at 60 days. Peroneal nerve function was present in half the rats at 60 days after surgery. Leflunomide combined with cyclosporine prevented whole limb allograft rejection across a major histocompatibility barrier.

Cyclosporine pharmacokinetics in cats following topical ocular administration.

Topical ocular administration of two forms of cyclosporine were studied in the cat. Both forms were able to produce measurable whole-blood levels capable of suppressing in vitro lymphocyte stimulation. The kinetics of cyclosporine following administration of either oral solution or cyclosporine in olive oil were variable, with peak concentrations ranging from 450 to 1033 ng/ml and 288 to 648 ng/ml, respectively. Absorption lag time ranged from 0 to 1.34 hr for oral solution, and 0.27 to 1.2 hr for cyclosporine in olive oil. The half-life of elimination ranged from 2.41 to 10.04 hr, and 3.09 to 15.75 hr, respectively. When compared with the commercially available oral solution, cyclosporine dissolved in olive oil was better tolerated during administration. Topical ocular administration of cyclosporine in cats offers a possible alternative method of treatment for individuals intolerant of oral administration. Topical ocular administration might also replace the need for intravenous administration of cyclosporine during perioperative periods or during periods of vomiting and nausea associated with rejection or other illnesses. Due to individual variation in absorption and elimination of topically applied cyclosporine, dosages in each cat must be determined by monitoring blood, plasma, or serum levels.

Enhanced nitric oxide production induced by the administration of L-arginine does not inhibit arterial neointimal formation after overwhelming alloimmune injury.

BACKGROUND: Nitric oxide suppresses proliferation and function of T cells and inhibits proliferation of smooth muscle cells in vitro and in vivo. The purpose of this study was to determine whether nitric oxide, stimulated by means of the oral administration of L-arginine, would reduce the degree of intimal thickening produced by immune injury in rat arterial allografts. METHODS: Orthotopic femoral artery transplantation was done with Brown Norway donors and Lewis recipients. Seven days before operation, and for 39 additional days, one group received 2.25% L-arginine and one group received 0.01% N-omega-nitro-L-arginine in tap water; one group received tap water only. Forty days after operation, all arterial segments were excised and examined by histopathologic, morphometric, and immunohistochemical assays. RESULTS: There was no difference in the rejection response or degree of intimal thickening among the three groups. There were no qualitative differences in numbers of T cells, macrophages, or smooth muscle cells in the neointima, media, or adventitia among the untreated and treated groups. Induced nitric oxide synthase was present in the media and adventitia of the allograft vessels, but not in native rat arteries. CONCLUSIONS: Enhanced production of nitric oxide, via the administration of L-arginine, has been shown to reduce tissue pathologic changes in models of mechanical or dietary injury. Enhanced nitric oxide production did not suppress rejection or inhibit intimal thickening in this model of immune-mediated injury.

Histologic evaluation of the crop for diagnosis of proventricular dilatation syndrome in psittacine birds.

Histologic sections of crop tissue were evaluated for the presence of lymphoplasmacytic infiltrates within mesenteric ganglia. All birds with proventricular dilatation syndrome that had lymphoplasmacytic infiltrates in crop ganglia had similar infiltrates in the proventricular and/or ventricular ganglia. False-negative crop biopsy results occurred approximately 24% of the time. More invasive procedures, such as proventricular or ventricular biopsy, may be necessary if the crop biopsy is nondiagnostic in a bird with clinical signs of proventricular dilatation syndrome.

Detection of eastern equine encephalomyelitis virus RNA in formalin-fixed, paraffin-embedded tissues using DNA in situ hybridization.

Eastern equine encephalomyelitis (F.EE) virus was detected in infected formalin-fixed horse and emu tissues and in infected chicken embryo fibroblasts. Results of in situ hybridization using a digoxigenin-labeled 40-base DNA probe complementary to a conserved region of the EEE virus RNA compared favorably with results of both virus isolation and serum neutralization tests. This technique may be useful for diagnosis of EEE virus infection in various animal species, especially when fresh tissues are not available for analysis, and also will provide a means for studying the involvement of alphaviruses in pathogenesis studies.

Detection and confirmation of reptilian adenovirus infection by in situ hybridization.

Adenovirus infections are documented in at least 12 different species of reptiles. In contrast to their mammalian and avian counterparts reptilian adenoviruses are not well characterized as to their pathogenic potential and their ability to cause primary disease. In the diagnostic setting, fresh tissues are often not available for virus isolation, and the confirmation of reptilian adenovirus infections is dependent largely upon electron microscopy for the identification of intranuclear viral inclusions associated with histopathologic changes. The diagnosis of adenovirus infection in 2 different species of snake was confirmed by the application of DNA in situ hybridization. Using an aviadenovirus specific oligoprobe, adenoviral DNA was observed in the nuclei of hepatocytes, Kupffer cells, endothelial cells, and enterocytes. Electron microscopy of the liver confirmed the presence of intranuclear viral particles morphologically consistent with an adenovirus. DNA in situ hybridization on formalin-fixed tissues can serve as a suitable alternative to electron microscopy in the diagnosis of reptilian adenovirus infections. Both affected snakes had other concurrent diseases, suggesting that the adenovirus may not have been the primary pathogen.

A functional model for whole limb transplantation in the rat.

To develop a functional model for the study of whole limb transplantation, inbred Lewis rats were used as both donors and recipients. In this model, the recipient biceps femoris muscle was elevated from its distal attachment to preserve part of the adductor function of the limb after surgery. The tibial, peroneal, and sural branches of the sciatic nerve were anastomosed separately to provide faster and more precise functional recovery. For control sensory evaluation, the saphenous branches of the femoral nerve were not reattached. A flat intramedullary pin stabilized with methyl methacrylate was used to rigidly immobilize the femur. The transplanted limbs started bearing weight at 17 to 22 days. Walking on the plantar surface of the hock and adduction of the toes gradually decreased, and the rats developed a normal walking pattern. Sciatic and tibial function indexes, based on walking track analysis, correlated well with clinical observations. In this study, a new model for limb transplantation was developed that provided good and reliable sensory and ambulatory recovery.

Long-term survival of a cat receiving a renal allograft from an unrelated donor.

A 6-year-old, spayed female Persian cat in terminal renal failure was referred to the Veterinary Medical Teaching Hospital for renal transplantation. An allograft from an unrelated donor was placed in the right iliac fossa and cyclosporine and prednisolone were administered as immunosuppressive agents. More than 18 months after surgery the cat was clinically normal and azotemia was absent.