Differentiation between acute cyclosporine nephrotoxicity and acute tubular necrosis using enalaprilat renal scintigraphy in rats

Toxicological evaluation of neem (Azadirachta indica) oil: acute and subacute toxicity

Neem (Azadirachta indica), popularly known as traditional medicine is a native plant in India. Neem oil is a vegetable oil derived from seeds or fruits of the neem tree through pressing or solvent extraction, and largely used in popular medicine to have antifungal, antibacterial, antimalarial, antiparasitic, anti-inflammatory, as well as immunemodulatory properties in different animal species. In the present study, acute and 28-day subacute toxicity tests were carried out. In the acute toxicity test, the LD50 values of neem oil were found to be 31.95g/kg. The subacute treatment with neem oil failed to change body weight gain, food and water consumption. Serum biochemistry analysis showed no significant differences in any of the parameters examined under the dose of 1600mg/kg/day. Histopathological exams showed that the target organs of neem oil were testicle, liver and kidneys up to the dose of 1600mg/kg/day.

Comprehensive mechanism-based antibody pharmacokinetic modeling

Pharmacokinetic models of antibody distribution and dynamics are useful for predicting and optimizing therapeutic behavior. Targeted antigens are produced and distributed in various tissues in specific patterns in disease phenotypes. Existing models leave out significant mechanistic detail which would enable an understanding of how to modify therapeutics in an optimal manner to allow appropriate tissue penetration in either a healthy or diseased state. The model presented here incorporates additional complexity such as diffusion through endothelial barriers, differential transcytosis properties, FcRn-mediated recycling, and incorporates these properties in an organ-specific manner. This creates a platform which can be expanded upon to include understanding of the effect of target on therapeutic distribution and clearance, differences in dynamics during a diseased versus healthy state, differential dose strategies, and mechanistic translation between animal models and human disease state. This model represents a superior alternative to typical and potentially over-simplified scaling strategies utilized in most existing physiologically-based pharmacokinetic models. Ultimately, this will enable better therapeutic design and greater pharmacological effects.

Non-invasive imaging of acute renal allograft rejection in rats using small animal F-FDG-PET

BACKGROUND

At present, renal grafts are the most common solid organ transplants world-wide. Given the importance of renal transplantation and the limitation of available donor kidneys, detailed analysis of factors that affect transplant survival are important. Despite the introduction of new and effective immunosuppressive drugs, acute cellular graft rejection (AR) is still a major risk for graft survival. Nowadays, AR can only be definitively by renal biopsy. However, biopsies carry a risk of renal transplant injury and loss. Most important, they can not be performed in patients taking anticoagulant drugs.

METHODOLOGY/PRINCIPAL FINDINGS

We present a non-invasive, entirely image-based method to assess AR in an allogeneic rat renal transplantation model using small animal positron emission tomography (PET) and (18)F-fluorodeoxyglucose (FDG). 3 h after i.v. injection of 30 MBq FDG into adult uni-nephrectomized, allogeneically transplanted rats, tissue radioactivity of renal parenchyma was assessed in vivo by a small animal PET-scanner (post operative day (POD) 1,2,4, and 7) and post mortem dissection. The mean radioactivity (cps/mm(3) tissue) as well as the percent injected dose (%ID) was compared between graft and native reference kidney. Results were confirmed by histological and autoradiographic analysis. Healthy rats, rats with acute CSA nephrotoxicity, with acute tubular necrosis, and syngeneically transplanted rats served as controls. FDG-uptake was significantly elevated only in allogeneic grafts from POD 1 on when compared to the native kidney (%ID graft POD 1: 0.54+/-0.06; POD 2: 0.58+/-0.12; POD 4: 0.81+/-0.06; POD 7: 0.77+/-0.1; CTR: 0.22+/-0.01, n = 3-28). Renal FDG-uptake in vivo correlated with the results obtained by micro-autoradiography and the degree of inflammatory infiltrates observed in histology.

CONCLUSIONS/SIGNIFICANCE

We propose that graft FDG-PET imaging is a new option to non-invasively, specifically, early detect, and follow-up acute renal rejection. This method is potentially useful to improve post-transplant rejection monitoring.

4-Week repeated intravenous dose toxicity study of a new camptothecin anticancer agent CKD-602 in dogs

CKD-602 is a new camptothecin derivative antitumor agent with a formula (7-[2-(N-isopropylamino)ethyl]-(20S)-camptothecin) developed by Chong Kun Dang Pharmaceutical Company in Korea. In the present study, the subacute toxicity of CKD-602 was investigated after 4-week repeated intravenous administration of the test chemical in beagle dogs. The test chemical was administered intravenously at dose levels of 0, 0.001, 0.005, or 0.01 mg/kg/day for 4 weeks to male and female dogs (n = 3 for male and female dogs for each dose). During the test period, clinical signs, mortality, body weights, food and water consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross findings, organ weights and histopathology were examined. In the high dose group, an increase in the incidence of abnormal clinical signs and a decrease in food and water intake and body weight gain were observed in both sexes. Hematological investigations revealed decreased white blood cells (WBC) in both sexes and reduced red blood cells (RBC), hemoglobin and hematocrit in females. Histopathological examinations revealed an increase in the incidence of atrophy of the sternal and femoral marrow and spleen in both sexes and atrophy of the thymus and mesenteric lymph node in males. No treatment-related adverse effects were observed in both sexes of the low and middle dose groups. In conclusion, the 4-week repeated intravenous dose of CKD-602 to beagle dogs caused increases in the clinical signs and histopathological changes, and decreases in the body weight gain, food and water intake, RBC, hemoglobin, hematocrit and WBC at the dose level of 0.01 mg/kg/day. In the present experimental conditions, the target organs were determined to be bone marrow, blood cells, spleen, thymus, and mesenteric lymph node. The no-observed-adverse-effect levels (NOAEL) for males and females were considered to be 0.005 mg/kg/day, respectively.

Subacute toxicity evaluation of a new camptothecin anticancer agent CKD-602 administered by intravenous injection to rats

The subacute toxicity of a new camptothecin anticancer agent, CKD-602, was investigated after 4-week repeated intravenous administration of the chemical in Sprague-Dawley rats. The test chemical was administered intravenously to rats at dose levels of 0, 0.003, 0.013, or 0.067 mg/kg/day for males and 0, 0.004, 0.018, or 0.089 mg/kg/day for females. At the end of the treatment period, 10 rats/sex/group were sacrificed. The remaining 5 rats/sex in the vehicle control and high dose groups continued the study without treatment for 2 weeks (recovery period). During the test period, clinical signs, mortality, body weights, food and water consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross findings, organ weights, and histopathology were examined. In both sexes of the high dose group, an increase in the incidence of abnormal clinical signs and paleness of the eyes, a reduction in the body weight gain, food consumption and urine protein, and an increase in the water consumption were observed. Hematological investigations revealed a decrease in the red blood cells, hemoglobin and hematocrit and an increase in the mean corpuscular volume, mean corpuscular hemoglobin, platelets, and reticulocytes in a dose-dependent manner. Serum total cholesterol and total protein values were lower in females than those of controls, but not in males. An increase in the heart and liver weights and a decrease in the thymus weight were also found. Histopathological alterations included an increase in the incidence of atrophy of the sternal marrow, atrophy, fibrosis and mast cell hyperplasia of the femoral marrow, atrophy of the white pulp and extramedullary hematopoiesis of the spleen, atrophy of the thymus, auricular hypertrophy of the heart, extramedullary hematopoiesis and centriacinar telangiectasis of the liver, follicular degeneration of the ovary, and inflammation of the tail. The major treatment-related effects were not recovered at the end of 2-week recovery period. There were no adverse effects in the low and middle dose groups of both genders. In the present experimental conditions, the target organs were determined to be bone marrow, blood cells, spleen, liver, thymus, and heart. The no-observed-adverse-effect level was considered to be 0.013 mg/kg/day for males and 0.018 mg/kg/day for females.