Comparison of the effects of caffeine and doxapram on respiratory and cardiovascular function in foals with induced respiratory acidosis

OBJECTIVE: To determine and compare the effects of caffeine and doxapram on cardiorespiratory variables in foals during isoflurane-induced respiratory acidosis. ANIMALS: 6 clinically normal foals (1 to 3 days old). PROCEDURES: At intervals of > or = 24 hours, foals received each of 3 IV treatments while in a steady state of hypercapnia induced by isoflurane anesthesia (mean +/- SD, 1.4 +/- 0.3% endtidal isoflurane concentration). After assessment of baseline cardiorespiratory variables, a low dose of the treatment was administered and variables were reassessed; a high dose was then administered, and variables were again assessed. Sequential low- and high-dose treatments included doxapram (loading dose of 0.5 mg/kg, followed by a 20-minute infusion at 0.03 mg/kg/min and then 0.08 mg/kg/min), caffeine (5 mg/kg and 10 mg/kg), and saline (0.9% NaCl) solution (equivalent volumes). RESULTS: Administration of doxapram at both infusion rates resulted in a significant increase in respiratory rate, minute ventilation, arterial blood pH, PaO(2), and arterial blood pressure. These variables were also significantly higher during doxapram administration than during caffeine or saline solution administration. There was a significant dose-dependent decrease in PaCO(2) and arterial bicarbonate concentration during doxapram treatment. In contrast, PaCO(2) increased from baseline values after administration of saline solution or caffeine. The PaCO(2) value was significantly lower during doxapram treatment than it was during caffeine or saline solution treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that doxapram restored ventilation in a dose-dependent manner in neonatal foals with isoflurane-induced hypercapnia. The effects of caffeine on respiratory function were indistinguishable from those of saline solution.     

Review of the Results of Common Carp (Cyprinus carpio) Breeding at a Large-Scale Hatchery

Long‐term data on the induced spawning of common carp (Cyprinus carpio) at a large‐scale hatchery were evaluated. Breeders at the farm prefer medium‐size fish with body weights between 4 and 8 kg. The number of females selected for propagation in the first period of the spawning season made up about half of the total number of females (47.5%). The average spawning ratio from the data of 2620 females receiving hormonal injections was 79.8%. From the egg production data of 2086 females, the average pseudogonadosomatic index (PGSI) was calculated as 16.3 ± 5.87% (mean ± SD) for the same period. There was a high correlation between fish weight and the time of induction, determined by the breeder on the basis of secondary sexual characteristics. The similarity of the responses of females among the different weight categories proved the reliability of this method for identification. The time of induction has a significant effect on both the responsiveness of the females and the relative quantity of eggs released. Spawning ratio was significantly lower in the third period of the reproductive season, compared with those in the first and second period. Mean PGSIfor the third period was significantly lower than that for the first period. The considerable decrease of both reproductive parameters by the end of the spawning season is attributed to ovarian atresia. The spawning ratio and the mean PGSIfor the mirror and scaled varieties were similar.     

ACCURACY OF A COMPUTED TOMOGRAPHY BRONCHIAL WALL THICKNESS TO PULMONARY ARTERY DIAMETER RATIO FOR ASSESSING BRONCHIAL WALL THICKENING IN DOGS

Computed tomography is increasingly being used in veterinary medicine to evaluate animals with pulmonary signs such as coughing, tachypnea, and exercise intolerance, however, a quantitative measure of bronchial wall thickening has yet to be validated in veterinary medicine. Canine chronic bronchitis is a disease that is characterized histologically by thickening of the bronchial walls. Thoracic CT images of 16 dogs with chronic bronchitis and 72 dogs presenting for conditions unrelated to cough were evaluated. A ratio comparing the bronchial wall thickness to the adjacent pulmonary artery diameter was obtained in the right and left cranial and caudal lung lobes. There was no significant difference in dogs with chronic bronchitis or unaffected dogs between the left and right hemithorax, patient weight, patient age, image slice thickness, or CT machine used. Dogs with chronic bronchitis were found to have a significantly greater ratio than unaffected dogs (P < 0.001). The ratios in the cranial lung lobes were found to be significantly greater than the caudal lung lobes in both chronic bronchitis and unaffected dogs (P < 0.001). A receiver operating characteristic curve of the ratios in the cranial lung lobes had an area under the curve of 0.912, indicating high accuracy in predicting for bronchial wall thickening. A ratio of ≥0.6 in the cranial lung lobes was found to have a sensitivity of 77% and specificity of 100% in predicting for the presence of chronic bronchitis, and we propose using this cut‐off as supportive of bronchial wall thickening on CT.     

In vitro susceptibility of Staphylococcus aureus strains isolated from cows with subclinical mastitis to different antimicrobial agents

Sensitivity to commercial teat dips (nonoxinol-9 iodine complex and chlorhexidine digluconate) of 56 Staphylococcus (S.) aureus strains isolated from quarter milk samples of various German dairy herds treated with different teat dipping schemes was investigated in this study. The minimum inhibitory concentration was determined using a broth macrodilution method according to the German Veterinary Association guidelines. The main objective of the current study was to induce in vitro resistance induction of S. aureus to chemical disinfectants. Ten different strains were repeatedly passed ten times in growth media with sub-lethal concentrations of disinfectants. Nine strains showed a significant reduction in susceptibility to the nonoxinol-9 iodine complex but only one strain developed resistance to chlorhexidine digluconate. Stability of the acquired resistance was observed in all S. aureus strains adapted to the nonoxinol-9 iodine complex and chlorhexidine digluconate. In contrast, simultaneous resistance to different antibiotics was not observed in any of the ten investigated S. aureus strains. However, the isolates exhibited a high degree of resistance to penicillin G. Based on these results, resistance of S. aureus to chemical disinfectants may be more likely to develop if the chemicals are used at concentrations lower than that required for an optimal biocidal effect.     

Activation of muscarinic potassium currents by ATP gamma S in atrial cells

Intracellular perfusion of atrial myocytes with adenosine 5'-(gamma-thio) triphosphate (ATP gamma S), an ATP analog, elicits a progressive increase of the muscarinic potassium channel current, IK(M), in the absence of agonists. In this respect, ATP gamma S mimics the actions of guanosine triphosphate (GTP) analogs, which produce direct, persistent activation of the guanyl nucleotide-binding (G) protein controlling the K+(M) channel. The effect of ATP gamma S on IK(M), however, differs from that produced by GTP analogs in two aspects: it requires relatively large ATP gamma S concentrations, and it appears after a considerable delay, suggesting a rate-limiting step not present in similar experiments performed with guanosine 5'-(gamma-thio) triphosphate (GTP gamma S). Incubation of atrial homogenates with [35S]ATP gamma S leads to formation of significant amounts of [35S]GTP gamma S, suggesting that activation of IK(M) by ATP gamma S arises indirectly through its conversion into GTP gamma S by cellular enzymes. ATP gamma S is often used to demonstrate the involvement of protein phosphorylation in the control of various cellular processes. The finding that cytosolic application of ATP gamma S can also lead to G-protein activation implies that experiments with ATP gamma S must be interpreted with caution.     

Evaluation of persistence of terbinafine in the hair of normal cats after 14 days of daily therapy

This study determined the residual concentration of terbinafine in cat hair after 14 days of oral treatment. Ten clinically normal cats were administered terbinafine orally at a daily dose of 34-45.7 mg kg(-1) for a total of 14 days. Areas of 15 cm(2) were shaved on the lateral thorax at day 0 and weekly for 8 weeks after the last dose of terbinafine. The hair samples were analysed by high-pressure liquid chromatography to determine the persistence of terbinafine over time. The mean terbinafine concentration in hair was 2.30 ng mg(-1) after 14 days of therapy. The half life was 1.84 weeks after the last dose of terbinafine. With a 99% confidence interval, the concentration of terbinafine remained in the cat hair at or above 0.03 ng mg(-1) (minimal inhibitory concentration (MIC)(90) = 0.03 microg mL(-1)) for 5.3 weeks. Slight deviations in the complete blood cell count and serum chemistry values were not attributed to terbinafine. Four cats experienced vomiting during the terbinafine treatment; two of these cats also experienced intense facial pruritus followed by a macular to papular skin reaction 7-14 days after the discontinuation of terbinafine. In summary, terbinafine persists in hair at concentrations above the MIC for several weeks after stopping medication, even after short-term therapy (14 days). These results suggest that pulse therapy of terbinafine should be further researched and potentially considered as a treatment modality for feline dermatophytosis, an approach that would decrease treatment duration while maintaining effectiveness.     

Entrainment of neuronal oscillations as a mechanism of attentional selection

Whereas gamma-band neuronal oscillations clearly appear integral to visual attention, the role of lower-frequency oscillations is still being debated. Mounting evidence indicates that a key functional property of these oscillations is the rhythmic shifting of excitability in local neuronal ensembles. Here, we show that when attended stimuli are in a rhythmic stream, delta-band oscillations in the primary visual cortex entrain to the rhythm of the stream, resulting in increased response gain for task-relevant events and decreased reaction times. Because of hierarchical cross-frequency coupling, delta phase also determines momentary power in higher-frequency activity. These instrumental functions of low-frequency oscillations support a conceptual framework that integrates numerous earlier findings.     

Potassium fertilization effects on isoflavone concentrations in soybean [Glycine max (L.) Merr.

Soybean isoflavone concentrations vary widely, but the contribution of soil fertility and nutrient management to this variability is unknown. Field experiments from 1998 to 2000 on soils with low to high exchangeable potassium (K) concentrations evaluated K application and placement effects on isoflavone concentrations and composition of soybean in various tillage and row-width systems. Soybean seed yield and concentrations of daidzein, genistein, glycitein, leaf K, and seed K were measured. Significant increases in daidzein, genistein, and total isoflavone were observed with direct deep-banded K or residual surface-applied K on low-K soils. Positive effects of K fertilization on isoflavones were less frequent on medium- to high-testing K soils. Both individual and total isoflavones were often positively correlated with seed yield, leaf K, and seed K on low-K soils. Appropriate K management could be an effective approach to increase isoflavone concentrations for soybeans produced on low- to medium-K soils.     

Continuous 500,000-year climate record from vein calcite in devils hole, nevada

Oxygen-18 (delta(18)O) variations in a 36-centimeter-long core (DH-11) of vein calcite from Devils Hole, Nevada, yield an uninterrupted 500,000-year paleotemperature record that closely mimics all major features in the Vostok (Antarctica) paleotemperature and marine delta(18)O ice-volume records. The chronology for this continental record is based on 21 replicated mass-spectrometric uranium-series dates. Between the middle and latest Pleistocene, the duration of the last four glacial cycles recorded in the calcite increased from 80,000 to 130,000 years; this variation suggests that major climate changes were aperiodic. The timing of specific climatic events indicates that orbitally controlled variations in solar insolation were not a major factor in triggering deglaciations. Interglacial climates lasted about 20,000 years. Collectively, these observations are inconsistent with the Milankovitch hypothesis for the origin of the Pleistocene glacial cycles but they are consistent with the thesis that these cycles originated from internal nonlinear feedbacks within the atmosphere-ice sheet-ocean system.