DOPPLER ULTRASONOGRAPHIC ESTIMATION OF RENAL AND OCULAR RESISTIVE AND PULSATILITY INDICES IN NORMAL DOGS AND CATS

Resistive index (RI) and pulsatility index (PI) are indirect measurements of blood flow resistance that may be used to evaluate vascular changes in renal and ophthalmologic diseases. To our knowledge, no reports are available describing values for renal and ocular PI index in the unsedated dog and ocular RI and PI indices in the unsedated cat. The purpose of this study was to measure normal values for both intrarenal and ocular RI and PI within the same subject in unsedated clinically normal dogs and cats. Twenty-seven dogs and 10 cats were considered healthy by means of physical examination, CBC, biochemical profile, urinalysis, and ultrasonography. Systolic blood pressure was measured by Doppler ultrasonography. Intrarenal and ocular arteries were scanned by pulsed Doppler ultrasonography to calculate RI and PI. No significant differences were noted between the values obtained for the right vs. the left kidney and eye. The upper values of these indices were calculated as mean+2 standard deviations resulting in 0.72 and 1.52 for dog renal RI and PI; 0.7 and 1.29 for cat renal RI and PI; 0.76 and 1.68 for dog ocular RI and PI; and 0.72 and 1.02 for cat ocular RI and PI.     

Observations on the potential of microwaves for weed control

Field tests of a prototype microwave‐based weed killer machine were conducted on Abutilon theophrasti, Panicum miliaceum, lucerne and oilseed rape pure stands. The approach can be considered a thermal weed control method, the microwave radiation causing dielectric heating of plant tissue water that eventually kills the plant. The method could overcome the limitations of other thermal methods, such as fire risk with flaming or the heavy loads required for hot water treatments. Species were effectively controlled by microwave irradiation, but their sensitivity and the evolution of damage symptoms over time differed. Lucerne showed no sigmoidal response and was the least affected by the treatment, while a log‐logistic curve expressed the dose–response relationships of the other species quite well. The estimated microwave dose for a 90% dry weight reduction ranged from 1015 kJ m^?2 in A. theophrasti to 3433 kJ m^?2 in P. miliaceum. Energy cost evaluation indicated that increased efficiency is required for this technique to compete with other thermal methods. Microwave efficiency could be increased by a flux configuration that minimizes soil penetration and maximizes absorption by plants, which, in turn, depends on plant growth form.     

Plasma Concentrations and Cardiovascular Influence of Lidocaine Infusions During Isoflurane Anesthesia in Healthy Dogs and Dogs With Subaortic Stenosis

Objective—To determine the plasma concentrations and cardiovascular changes that occur in healthy dogs and dogs with aortic stenosis that are given an infusion of lidocaine during isoflurane anesthesia. Study Design—Phase 1, controlled randomized cross-over trial; Phase 2, before and after trial Animals—Phase 1, 6 healthy dogs (4 female, 2 male) weighing 23.8 ± 7.4 kg; Phase 2, 7 dogs (4 female, 3 male) with moderate to severe subaortic stenosis (confirmed by Doppler echocardiography) weighing 31.1 ± 14.5 kg. Methods—After mask induction, intubation, and institution of positive pressure ventilation, instrumentation was performed to measure hemodynamic variables. After baseline, measurement at an end-tidal isoflurane concentration of 1.9% (phase 1) or 1.85% (phase 2), a loading dose infusion of lidocaine at 400 μg/kg/min was given. Phase 1: Maintenance doses of lidocaine were administered consecutively (40, 120, and 200 μg/kg/min) after the loading dose (given for 10, 10, and 5 minutes, respectively) in advance of each maintenance concentrations. Measurements were taken at the end of each loading dose and at 25 and 35 minutes during each maintenance level. The same animals on a different day were given dextrose 5% and acted as the control. Phase 2: Dogs were studied on a single occasion during an infusion of lidocaine at 120 μg/kg/ min given after the loading dose (10 minutes). Measurements occurred after the loading dose and at 25 and 35 minutes. A blood sample for lidocaine concentration was taken at 70 minutes. Data were compared using a one-way ANOVA for phase 1, and between phase 1 and 2. Statistical analysis for phase 2 was performed using a paired r-test with a Bonferroni correction. A P value ± .05 was considered significant. Results—Phase 1: Plasma lidocaine concentrations achieved with 40, 120, and 200 μg of lidocaine/kg/min were 2.70, 5.27, and 7.17 μg/mL, respectively. A significant increase in heart rate (HR) (all concentrations), central venous pressure (CVP), mean pulmonary areterial pressure (PAP), and a decrease in stroke index (SI) (200 μg/kg/min) were observed. An increase in systemic vascular resistance (SVR) and mean PAP, and a decrease in SI also followed the loading dose given before the 200 μg/kg/min infusion. No other significant differences from the control measurements, during dextrose 5% infusion alone, were detected. Phase 2: Plasma lidocaine concentrations achieved were 5.35, 4.23, 4.23, and 5.60 μg/mL at 10, 25, 35, and 70 minutes, respectively. They were not significantly different from concentrations found in our healthy dogs at the same infusions. A significant but small increase in CVP compared with baseline was noted after the loading dose. There were no significant differences from baseline shown in all other cardiovascular data. There were no statistically significant differences in any measurements taken during the lidocaine infusion between the dogs in phase 1 and phase 2. Dogs with aortic stenosis tended to have a lower cardiac index than healthy dogs at baseline (88 v 121 mL/kg/min) and during lidocaine infusion (81 v 111 mL/kg/min). A small, statistically significant difference in systolic PAP was present at baseline. Conclusions—There does not appear to be any detrimental cardiovascular effects related to an infusion of lidocaine at 120 μg/kg/min during isoflurane anesthesia in healthy dogs or dogs with aortic stenosis. The technique used in this study resulted in therapeutic plasma concentrations of lidocaine. Clinical Relevance—Methods shown in the study can be used in clinical cases to achieve therapeutic lidocaine levels without significant cardiovascular depression during isoflurane anesthesia.     

Localization of Oestrogen Receptors in the Epididymis During Sexual Maturation of the Domestic Cat

Oestrogens are involved in regulation of spermatogenesis and sperm maturation and are essential for male fertility. To study the role of oestrogens on epididymal function in the domestic cat, we analyzed the localization patterns of oestrogen receptors (ERs) within the epididymis of juvenile, pubertal and adults using immunohistochemistry. Cat epididymal tissues obtained during routine castrations were fixed in chilled Bouin's solution and processed for immunohistochemistry with ER-specific antibodies. For a certain receptor type, ER localization was influenced by donor age. In the juvenile epididymis, ERα was localized in the nuclei of epithelial cells of efferent ducts and undifferentiated epithelium of the ductus epididymis. During puberty, ERα localization in the undifferentiated epithelium of the epididymis shifted from the nuclei to the cytoplasm and plasma membrane. Oestrogen receptor-α level was highest in the pubertal and adult epididymis, especially within the cytoplasm and in plasma membranes of caput epithelial cells. This finding was suggestive of a role in fluid reabsorption within the efferent ducts and the epididymis. In corpus and cauda regions, ERα was less abundant, suggesting a minor role for oestrogens in sperm storage areas. Interestingly, localization of ERβ was neither influenced by age nor location within the epididymis and was ubiquitous throughout. Results demonstrate that oestrogen actions within the epididymis may be predominantly mediated through ERα during sexual maturation in the domestic cat.     

有机物-金属相互作用对重金属负载土柱中粘土矿物吸附剂再生的影响

Natural clay minerals can play an important role in crude remediation of wastewater polluted with the heavy metals (HMs) Cu,Zn and Ni.The presence and timing of addition of natural dissolved organic matter (DOM) have a significant effect on the HM removal by clay mineral sorbents.However,the influence of the presence of DOM on the remediation of the used clay mineral sorbents once saturated with HMs is largely unknown.To resolve this,clay mineral-rich soil column of varying composition,loaded (i) with Cu,Zn and Ni only,(ii) first with DOM followed by Cu,Zn and Ni,or (iii) with DOM,Cu,Zn and Ni simultaneously,was used in a set of desorption experiments.The soil columns were leached with 0.001 mol L-1 CaCl2 dissolved in water as control eluent and 0.001 mol L-1 CaCl2 dissolved in DOM as treatment eluent.During the preceding loading phase of the sorbent,the timing of DOM addition (sequential or concurrent with HMs) was found to have a significant influence on the subsequent removal of the HMs.In particular when the column was loaded with DOM and HMs simultaneously,largely irreversible co-precipitation took place.Our results indicate that the regeneration potential of clay mineral sorbents in wastewater treatment will be significantly reduced when the treated water is rich in DOM.In contrast,in manured agricultural fields (where HMs enter together with DOM),HM mobility will be lower than expected from interaction dynamics of HMs and clay minerals.