Radiosensitivity and capacity for radiation-induced sublethal damage repair of canine transitional cell carcinoma (TCC) cell lines

Understanding the inherent radiosensitivity and repair capacity of canine transitional cell carcinoma (TCC) can aid in optimizing radiation protocols to treat this disease. The objective of this study was to evaluate the parameters surviving fraction at 2 Gy (SF(2) ), α/β ratio and capacity for sublethal damage repair (SLDR) in response to radiation. Dose-response and split-dose studies were performed using the clonogenic assay. The mean SF(2) for three established TCC cell lines was high at 0.61. All the three cell lines exhibited a low to moderate α/β ratio, with the mean being 3.27. Two cell lines exhibited statistically increased survival at 4 and 24 h in the dose-response assay. Overall, our results indicate that the cell lines are moderately radioresistant, have a high repair capacity and behave similarly to a late-responding normal tissue. These findings indicate that the radiation protocols utilizing higher doses with less fractionation may be more effective for treating TCC.     

Use of whole blood for spectrophotometric determination of cholinesterase activity in dogs

Whole blood has been compared with erythrocytes and plasma for spectrophotometric cholinesterase determination in the dog. Cholinesterase activity was characterized using two substrates: acetylthiocholine and butyrylthiocholine. Acetylcholinesterase was the only form of cholinesterase present on erythrocytes and hydrolysed only acetylthiocholine. Butyrylcholinesterase (pseudocholinesterase) was predominant in plasma, hydrolysing mainly butyrylthiocholine. Based on these results, a method based on the use of two substrates (acetylthiocholine for monitoring acetylcholinesterase and butyrylthiocholine for determining butyrylcholinesterase) in the same whole blood sample is recommended for canine cholinesterase analysis. This way of monitoring both enzymes can be easily automated, yielding good within (CVs < 5%) and between-run (CVs < 7%) precision.     

Effects of a hydrolyzed collagen dressing on the healing of open wounds in dogs

OBJECTIVE: To determine the effects of a hydrolyzed bovine collagen dressing (HBCD) on healing of open wounds in healthy dogs. ANIMALS: 9 female Beagles. PROCEDURES: 2 full-thickness skin wounds were made bilaterally on the trunk of each dog. Wounds on 1 side were treated with powdered HBCD covered with a semiocclusive nonadherent bandage. Wounds on the other side (control wounds) were covered with a semiocclusive nonadherent bandage only. Wound healing was subjectively assessed, and percentage increase in tissue perfusion was assessed by use of laser Doppler perfusion imaging (LDPI). Planimetry was performed to determine the percentages of contraction, epithelialization, and total wound healing. Biopsy specimens were examined microscopically to evaluate histologic changes. RESULTS: The HBCD did not induce a strong inflammatory reaction, as reflected by results of LDPI and histologic examination. Moreover, HBCD appeared hydrophilic and provided an environment to keep wounds clean and enhance early epithelialization. After treatment for 7 days, treated wounds had a significantly greater percentage of epithelialization than control wounds (12.13 vs. 7.03%). CONCLUSION AND CLINICAL RELEVANCE: The hydrophilic property of HBCD may cleanse contaminated wounds with the body's homeostatic fluids and enhance early wound epithelialization.     

Canine X-linked severe combined immunodeficiency.

Canine X-linked severe combined immunodeficiency (XSCID) is due to mutations in the common gamma (gamma c) subunit of the IL-2, IL-4, IL-7, IL-9 and IL-15 receptors. The most striking clinical feature is a failure to thrive or 'stunted' growth. Recurrent or chronic infections begin at the time of decline of maternal antibody, usually between six and eight weeks of age. Affected dogs rarely survive past three to four months of age. The major pathologic feature of canine XSCID is a small, dysplastic thymus. Grossly identifiable lymph nodes, tonsils, and Peyer's patches are absent in XSCID dogs. During the neonatal period, XSCID dogs have few, if any, peripheral T cells and increased number of peripheral B cells. Some XSCID dogs do develop phenotypically mature, nonfunctional T cells with age, however, the absolute number of peripheral T cells remain significantly decreased compared to age-matched normal dogs. An interesting finding is that as soon as T cells begin to appear in XSCID dogs they rapidly switch from a CD45RA+ (naive) phenotype to a CD45RA- (activated or memory phenotype). One of the characteristic findings in XSCID dogs is an absent or markedly depressed blastogenic response of T cells in response to stimulation through the T cell receptor and when the necessary second messengers for cellular proliferation are directly provided that by-pass signals delivered through ligand-receptor interaction. The proliferative defect is due to the inability of T cells to express a functional IL-2 receptor. Canine XSCID B cells do not proliferate following stimulation with T cell-dependent B cell mitogens, however, they proliferate normally in response to T cell-independent B cell mitogens. Canine XSCID B cells are capable of producing IgM but are incapable of class-switching to IgG antibody production following immunization with the T cell-dependent neoantigen, bacteriophage phiX174. The number of thymocytes in the XSCID thymus is approximately 0.3% of the thymocytes present in the thymus of age-matched normal dogs. The proportion of CD4-CD8- thymocytes in XSCID dogs is increased 3.5-fold and the CD4+CD8+ population is decreased 2.3-fold. These findings demonstrate that (1) a functional gamma c is required for normal B and T cell function, (2) early T cell development is highly dependent upon a functional gamma c, and (3) B cell development can occur through a gamma c-independent pathway.     

Effects of Supplementing a Basal Diet of Chloris gayana Hay with One of Three Protein-rich Legume Hays of Cassia rotundifolia,Lablab purpureus and Macroptilium atropurpureum Forage on Some Nutritional Parameters in Goats

Growth and digestibility experiments were conducted on growing East African type goats offered Chloris gayana hay supplemented with one of three high-protein (119–128 g CP/kg DM) legume hays, Cassia rotundifolia (cassia), Lablab purpureus (lablab) or Macroptilium atropurpureum (siratro), and crushed maize to investigate the feed intake, digestibility, growth and urinary excretion of purine derivatives. Goats in the supplemented groups had higher total dry matter and nitrogen intakes and higher N retention and body mass gains than unsupplemented counterparts. The digestibility of dry matter, organic matter and neutral detergent fibre were increased by protein supplementation. Animals on supplemented diets had higher fractional outflow rates of particulate matter from the rumen. The production of protein by ruminal microbes and the efficiency of microbial N production were increased by supplementation. It was concluded that a mixture of low-quality grass hay (61.9 CP/kg DM) and either cassia, lablab or siratro hay, and maize grain can provide a productive balanced diet for growing goats.