A Prospective Study Of Intravenous Catheter Contamination

A one year prospective study was conducted to determine the association between intravenous catheter contamination and increased dwell time, and to identify any related risk factors. Intravenous catheters obtained from 23 cats and 98 dogs in the Intensive Care Unit at the Ontario Veterinary College with dwell times > 72 hours for the test group (n=58) and < 72 hours for a corresponding control group (n=63) were cultured between April 1991 and March 1992. One hundred and twenty one catheters were cultured, 16 jugular, 99 cephalic, and 6 saphenous. The overall contamination rate was 13 out of 121 catheters cultured (10.7%); 9/63 (14.3%) control and 4/58 (6.9%) test catheters. The bacteria isolated were E.aerogenes, S.aureus (3), P.aeruginosa, P.multocida, and Bacillus sp (7). The Bacillus sp positive catheters (5 control and 2 test) were placed during a five day period, and contaminated gauze squares were identified as the source of infection in these catheters. After these were removed from the study, the group infection rate was 6.9% control and 3.6% test. There was no significant difference between groups and no associated risk factors were identified. We conclude that intravenous dwell time need not be restricted to <72 hours.     

Preliminary study of plasma vascular endothelial growth factor (VEGF) during low- and high-dose radiation therapy of dogs with spontaneous tumors

High plasma vascular endothelial growth factor (VEGF) concentrations are associated with radiation resistance and poor prognosis. After an exposure to ionizing radiation in cell culture an early phase and a late phase of increased VEGF have been documented. The activation was dependent on the radiation dose. Therefore, the purpose of this study was to measure baseline plasma VEGF and changes in VEGF over the course of fractionated radiation therapy in dogs with spontaneous tumors. Dogs with tumors had a significantly higher pretreatment plasma VEGF than did dogs without tumors. Immediately after irradiation no increased plasma VEGF was observed. Over the course of radiation therapy there was an increased plasma VEGF in dogs treated with low doses per fraction/high total dose, whereas plasma VEGF remained stable in dogs irradiated with high doses per fraction/low total dose. The regulatory mechanisms are very complex, and therefore the value of plasma VEGF measurements as an indirect marker of angiogenesis induced by radiotherapy is limited.     

Case of suspected theobromine poisoning in dairy cattle

High-yielding dairy cows collapsed and died displaying signs of a disturbed central nervous system (muscle tremor, convulsion) and a considerably reduced body condition score. An intense diagnostic screening did not allow to confirm a definite diagnosis. Therefore, further analyses including an evaluation of feeds and feeding were initiated. The herd was fed a total mixed ration (TMR) based on corn and grass silage of moderate nutritive value supplemented with various amounts of chocolate chips. In retrospect, the amount of chocolate chips added to the respective TMR batches could not be quantified. These chips were purchased from a company producing bakery and chocolate products for human consumption and added to the silage and therefore to the TMR in order to increase the energy intake of the animals. Because the TMR, which was fed during the time of the incidence, was no longer available, a sample of a later batch of silage was examined. The amount of chocolate chips was quantified (0.44% per fresh matter), and a theobromine analysis was performed in the chocolate chips of the available batch (69.7 mg/100 g fresh matter). Because of the possible link between chocolate intake and observed signs, an immediate cessation of using the chocolate chips was recommended in addition to an optimisation of the TMR, that is an increase of the energy density. Even though the theobromine intake during the time of the incidence is unknown and information about toxicity of theobromine in ruminants is limited, we suspect that the feeding of chocolate in this case caused all signs including the sudden death of the cows. Further reasons are that no differential diagnoses were established and the problems at the farm stopped after removing the chocolate from the TMR.     

Photodynamic therapy of feline cutaneous squamous cell carcinoma using a newly developed liposomal photosensitizer: preliminary results concerning drug safety and efficacy

BACKGROUND: Squamous cell carcinomas are common skin tumors in cats. We investigated photodynamic therapy (PDT) using a new liposomal photosensitizer as a minimally invasive, effective treatment that can be easily performed while achieving good cosmetic results. AIM: The goal of this study was to assess and describe possible toxicities using a liposomal formulation of the photosensitizer meta-(Tetrahydroxyphenyl)Chlorin (m-THPC) and investigate if favorable pharmacokinetics translate into favorable tumor response and control. ANIMALS: Eighteen client-owned cats with 20 spontaneous cutaneous squamous cell carcinomas were included in the study. METHODS: PDT was performed using a new, liposomal formulation of the photosensitizer. Toxicity, tumor response, and tumor control were evaluated retrospectively. RESULTS: No general adverse effects were observed in cats treated with the new liposomal formulation. Mild local toxicity such as erythema and edema were seen in 15% of the patients. All cats responded to therapy, with a complete response rate of 100%. The overall 1-year control rate was 75%. The tumor recurrence rate was 20% with a median time to recurrence of 172.25 +/-87.1) days. CONCLUSIONS AND CLINICAL IMPORTANCE: A new liposomal photosensitizer was successfully used for squamous cell carcinoma in cats and was well tolerated. There were no systemic adverse effects observed with the liposomal formulation. The favorable pharmacokinetics of the liposomal drug resulted in a favorable tumor response.     

Extracellular heat shock protein 70 levels in tumour-bearing dogs and cats treated with radiation therapy and hyperthermia

Hyperthermia is a form of a cancer treatment which is frequently applied in combination with radiotherapy (RT) to improve therapy responses and radiosensitivity. The mode of action of hyperthermia is multifactorial; the one hand by altering the amount of the blood circulation in the treated tissue, on the other hand by modulating molecular pathways involved in cell survival processes and immunogenic interactions. One of the most dominant proteins induced by hyperthermia is the major stress-inducible heat shock protein 70 (Hsp70). Hsp70 can be found in the blood either as a free-protein (free HSP70) derived from necrotic cells, or lipid-bound (liposomal Hsp70) when it is actively released in extracellular vesicles (EVs) by living cells. The aim of the study was to evaluate the levels of free and liposomal Hsp70 before and after treatment with RT alone or hyperthermia combined with radiotherapy (HTRT) in dogs and cats to evaluate therapy responses. Peripheral blood was collected from feline and canine patients before and at 2, 4, 6 and 24 h after treatment with RT or HTRT. Hsp70 enzyme-linked immunosorbent assays (ELISAs) were performed to determine the free and liposomal Hsp70 concentrations in the serum. The levels were analysed after the first fraction of radiation to study immediate effects and after all applied fractions to study cumulative effects. The levels of free and liposomal Hsp70 levels in the circulation were not affected by the first singular treatment and cumulative effects of RT in cats however, after finalizing all treatment cycles with HTRT free and liposomal Hsp70 levels significantly increased. In dogs, HTRT, but not treatment with RT alone, significantly affected liposomal Hsp70 levels during the first fraction. Free Hsp70 levels were significantly increased after RT, but not HTRT, during the first fraction in dogs. In dogs, on the other hand, RT alone resulted in a significant increase in liposomal Hsp70, but HTRT did not significantly affect the liposomal Hsp70 when cumulative effects were analysed. Free Hsp70 was significantly induced in dogs after both, RT and HTRT when cumulative effects were analysed. RT and HTRT treatments differentially affect the levels of free and liposomal Hsp70 in dogs and cats. Both forms of Hsp70 could potentially be further investigated as potential liquid biopsy markers to study responses to RT and HTRT treatment in companion animals.     

Agricultural practice changes with cultivating genetically modified herbicide-tolerant oilseed rape

To facilitate weed suppression, oilseed rape or canola (Brassica napus) has been genetically modified (GM) over the last two decades to incorporate herbicide tolerance (HT). The introduction of oilseed rape in commercial agriculture raises concerns about potential adverse agronomic and environmental effects linked to both the genetic modification and altered agricultural practice. How will this new crop modify the existing cropping practice? What are the potential agro-environmental implications of its introduction? This paper analyses and schematises recorded and conceivable agricultural practice changes with GMHT oilseed rape introduction and its likely agro-environmental effects. It develops a conceptual systematics of influencing factors, subsequent practice changes and likely agro-environmental effects. The results can be used to design the mandatory monitoring of adverse GM crop effects.     

Binding Sites for Ca2+-Channel Effectors and Ryanodine in Periplaneta americana—Possible Targets for New Insecticides

The calcium channel and the ‘calcium release channel’ of muscle membrane of the cockroach Periplaneta americana have been characterized. Biological assays with calcium channel blockers and ryanodine on different insects and acari revealed pronounced insecticidal effects with ryanodine, but not with calcium channel blockers, at concentrations between 0·1 and 300 μg ml⁻¹. Skeletal muscle membranes derived either from the tubular network or from the sarcoplasmatic reticulum of P. americana were characterized with respect to the binding of the dihydropyridine (DHP) [³H]isradipine (PN 200-110), the phenyl-alkylamine [³H]verapamil and the alkaloid [³H]ryanodine. Preliminary binding studies with the benzothiazepine [³H]diltiazem suggest a low-affinity binding site with a IC₅₀ value of 3·3 μM . All binding sites tested were sensitive to treatment with proteinase K. Optimal conditions for binding of the radioligand ryanodine revealed the highest specific binding at pH 8 and at calcium chloride concentrations between 100 and 500 μM . EGTA at 10 μM abolished 95% of the ryanodine binding. Binding studies with calcium channel binding sites revealed a pronounced effect of low Ca²⁺ concentrations on specific isradipine binding, whereas verapamil and diltiazem binding were only reduced by the presence of 200 μM EGTA. With respect to high Ca²⁺ concentrations, specific binding of diltiazem, isradipine and verapamil was reduced by 73, 40 and 20%, respectively, at 5 mM Ca²⁺. Radioligand binding experiments showed high-affinity binding sites for ryanodine and isradipine. K_D values of 0·95 nM (B_max=550 fmol mg⁻¹ protein) and 0·75 nM (B_max=213 fmol mg⁻¹ protein) were determined respectively. A lower-affinity binding site was identified in binding studies with verapamil (K_D=7·4 nM and B_max=27 fmol mg⁻¹ protein). [³H]isradipine displacement studies with several dihydropyridines revealed the following ranking of affinity: nitrendipine>isradipine>Bay K8664≪nicardipine. Displacement of [³H]verapamil binding by effectors of the phenylalkylamine binding site showed that bepridil and S(-)verapamil had the highest affinities of the compounds tested followed by (±)verapamil, nor-methylverapamil and R(+)verapamil.     

Sterols that modify moulting in insects

The development of insects is under the control of a steroid hormone, ecdysone. This paper reviews suicide substrate type inactivators designed to inhibit the biosynthesis of ecdysone. Several series of acetylenic derivatives of cholesterol were synthesized and their biological effects on the prothoracic glands of the locust were investigated in vitro, enabling structure-activity relationships to be studied. Information on the ability of brassinosteroids, a series of plant growth regulators, to inhibit ecdysteroid activities of insects is discussed as a precursor to a study of brassinosteroid ecdysone mimics.