Pharmacokinetics of meloxicam in adult goats: a comparative study of subcutaneous,oral and intravenous administration

AIMS: To determine the plasma disposition of meloxicam in goats following S/C, oral or I/V administration at a single dose of 0.5?mg/kg bodyweight.

METHODS: Five healthy Saanen goats, aged 12–14 months and weighing 35–40?kg, were used for a three phase cross-over design with a 10-day washout period, with meloxicam administered I/V, then orally and S/C. Heparinised blood samples (5?mL) were collected from all animals prior to drug administration (0 hours) and subsequently up to 96 hours. Concentrations of meloxicam in plasma were measured using high performance liquid chromatography. Concentration-time curves were fitted and pharmacokinetic parameters were estimated for each administration group.

RESULTS: Subcutaneous administration of meloxicam exhibited unique plasma distribution characteristics that differed from oral and I/V administration. Mean peak plasma concentrations were greater (1.91 (SD 0.39) vs. 0.71 (SD 0.17) µg/mL) and the time to reach them shorter (3.20 (SD 1.64) vs. 14.33 (SD 2.19) hours) following S/C compared with oral administration (p<0.05). The terminal half-life was longer (15.16 (SD 4.74) vs. 10.69 (SD 1.49) hours) and the MRT was shorter (15.67 (SD 2.37) vs. 24.33 (SD 3.12) hours) following S/C than oral administration (p<0.05), but bioavailability was similar (98.24 (SD 9.62) vs. 96.49 (SD 10.71)%).

CONCLUSION AND CLINICAL RELEVANCE: Subcutaneous administration of meloxicam resulted in long-term presence of drug at high concentration in goat plasma. This unique plasma disposition characteristic may offer an advantage in some clinical cases towards potentially improving the treatment efficacy in goats.     

On the magnitude and dynamics of eddy covariance system residual energy (energy balance closure error) in subsurface drip-irrigated maize field during growing and non-growing (dormant) seasons

We investigated the magnitude and dynamics of the eddy covariance system (ECS) residual energy (energy balance closure error) for a subsurface drip-irrigated maize (Zea mays L.) field in 2005 and 2006 growing and non-growing (dormant) seasons. The corrections for coordinate rotation, oxygen, frequency, and Webb–Pearman–Leuning corrections improved the slope of the total convective energy (latent heat + sensible heat) with respect to the net available energy (from 0.68 to 0.84), but the data filtering (for horizontal and frictional wind speeds higher than 2 m s^?1 and lower than 0.2 m s^?1) had little effect on the slope. Also, the number of data points available for the analyses was reduced by 53 % after filtering. Overall, the daytime residual energy varied between ?100 and 200 W m^?2 during the dormant seasons and between ?500 and 600 W m^?2 during the growing seasons. Most of the nighttime residual energy ranged within ±40 W m^?2 during the calendar year in 2005 and within ?60 and 20 W m^?2 in 2006. During nighttime, the total convective energy is vertically distributed with respect to (R _n ? G), indicating that the total convective energy is independent of the variations in (R _n ? G). Secondly, it was observed that nighttime residual energy did not show any seasonal variation patterns throughout the two consecutive years and confined mostly within a narrow range of ±40 W m^?2, showing no dependency on seasonal changes in surface conditions. The maximum variation in residual energy was usually around frictional wind speed of 0.3–0.5 m s^?1 (varying between ?150 and 300 W m^?2) and then decreasing to a range of ±100 W m^?2 at higher frictional wind speeds. On average, the residual energy decreased by about 33 W m^?2 (after the intercept) for every 1.0 m s^?1 increase in frictional wind speed, whereas the residual energy decreased by about 4 W m^?2 (after the intercept) for every 1.0 m s^?1 increase in horizontal wind speed. Similar diurnal residual energy distribution patterns, with different magnitudes, were observed during growing and dormant seasons. Even though a slight decrease in residual energy was observed with increase in leaf area index (LAI) in both growing seasons, LAI did not have considerable influence on the seasonal variation in the residual energy. The residual energy was also evaluated by separating the data into morning and afternoon hours. We observed that the root-mean-squared difference value is slightly greater for the morning data than the afternoon, indicating greater residual energy in the morning hours due to weaker turbulent mixing than the afternoon. Overall, significant reduction in the available evapotranspiration data after applying a series of corrections possess challenges in terms of utilization of ECS for in-season irrigation management and crop water requirement determinations that needs to be further researched and addressed.     

Endometrial adenocarcinoma in two young queens

Endometrial adenocarcinoma is described in two young intact female Persian cats presented with haemorrhagic vaginal discharge. The discharge had been present for 3 and 15 days in each case, respectively. On the basis of signalment, history, clinical, laboratory and diagnostic imaging findings a tentative diagnosis of pyometra was made in each cat and ovariohysterectomy was subsequently performed. Histological examination revealed endometrial adenocarcinoma in both cats together with ovarian luteal cysts and pyometra in one case. Immunohistochemistry revealed a diffuse and strongly positive reaction for oestrogen receptors in the nuclei of glandular epithelium in well‐differentiated areas of the neoplastic tissue. Poorly differentiated areas of solid growth pattern had weak and focal expression of oestrogen receptors. Furthermore, the neoplastic cells within these areas displayed moderate to strong diffuse nuclear staining with Ki‐67 antibody suggestive of a high proliferative capacity. The owners reported that the cats were clinically healthy 23 and 21 months after the surgery. These cases highlight the importance of histological examination of surgically resected tissue even when clinical signs and laboratory findings suggest pyometra.     

Changes of HCO3-/Cl- exchanger activity during meiotic maturation in Balb/c strain mouse oocytes and zygotes

Intracellular pH-regulatory mechanisms are acquired by growing mouse oocytes with meiotic competence, and these mechanisms become fully active when the oocytes develop to the germinal vesicle (GV) stage as shown in CF1 and Balb/c strains mice. On the other hand, there is some evidence showing that intracellular pH-regulatory mechanisms are inhibited at the stages of Metaphase I (MI) and II (MII) oocytes in the CF1 strain mouse and hamster. Since it has been shown that the intracellular pH regulatory mechanism can be functionally different among mouse strains (e.g., CF1, Balb/c), the aim of this study was to investigate the activity of HCO3-/Cl- exchanger (anion exchanger, AE), which protects cells against alkalosis during the meiotic maturation process, in the GV oocyte up to the pronuclear (PN) zygote derived from the Balb/c strain mouse. Intracellular pH (pHi) was recorded using a microspectrofluorometric technique during meiotic maturation stages. KSOM-based solutions were used as culture and recording solutions. AE activity was determined using a Cl- removal assay and was reported as the change in pHi per minute. AE activity was high in GV stage oocytes but was significantly inhibited at the MI and MII stages. AE activity was higher in the PN zygote stage. This activity was significantly inhibited in all oocyte and zygote stages by 4,4'-Diisocyanatostilbene-2,2'-disulfonic acid disodium salt. After alkalosis induction, the pHi of MI and MII stage oocytes did not completely recover; however, almost complete recovery occurred in the GV stage oocytes and PN zygotes. These results suggest that AE is inhibited during the meiotic maturation process in the Balb/c strain mouse.     

Use of cardiac troponin kits for the qualitative determination of myocardial cell damage due to traumatic reticuloperitonitis in cattle

This study was designed to investigate whether kits to measure circulating cardiac troponin-I (cTn-I) and cardiac troponin-T (cTn-T) can be used to determine myocardial cell damage in cattle with traumatic reticuloperitonitis (trp). Twenty cattle with trp were compared with 10 clinically healthy cattle. cTn-I and cTn-T were determined qualitatively and cTn-I was determined quantitatively; biochemical analyses were also performed on both groups. The mean serum concentrations of total protein, globulin, glucose and calcium, and the mean activities of creatine kinase mb, aspartate aminotransferase, lactate dehydrogenase and gamma-glutamyl transferase were higher in the cattle with trp than in the control group. The cTn-I and cTn-T kits both gave positive results in three of the cattle with trp and the quantitative measurement of cTn-I was positive in 11 of the trp cases. Both tests were negative in the healthy cattle.     

Dose-Dependent Immunohistochemical Changes in Rat Cornea and Retina after Oral Methylphenidate Administration

Methylphenidate hydrochloride (MPH), more commonly known as Ritalin, is a piperidine derivative and is the drug most often used to treat attention deficit/hyperactivity disorder, one of the most common behavioural disorders of children and young adults. The aim of this study was to investigate dose-dependent immunohistochemical Dopamine 2 receptor (D2) expression and apoptosis in the rat cornea and cornea. In this study, 27 female pre-pubertal Wistar albino rats, divided into three different dose groups (5, 10 and 20 mg/kg) and their control groups, were used. They were treated orally with methylphenidate dissolved in saline solution for 5 days per week during 3 months. At the end of the third month, after perfusion fixation, eye tissue was removed. Paraffin sections were collected for immunohistochemical and terminal deoxynucleotidyl-transferase-mediated dUTP-biotin nick end labelling assay studies. In our study, we observed that the cornea D2 receptor reactivity showed a dose-related increase after MPH treatment, especially in basal cells of the epithelium and a dose-dependent decrease in the retinal ganglion cell which was statistically meaningful. Analysis of the cornea thickness results showed no meaningful difference between groups. Apoptotic cell number showed a meaningful increase in the high dose treated group compared to the other groups of the study. The data suggest that Ritalin has degenerative effect on the important functional part of the eye, such as cornea and retina and its activating dopaminergic mechanism via similar neuronal paths, functionally and structurally, to induce morphological changes. As a result, we believe that this morphological changes negatively effecting functional organization of the affected cornea and retina.     

Effect of polypropylene fiber cross sectional shapes on some structural/mechanical fiber properties and compressibility behaviour of plain knitted fabrics

Synthetic fibers are generally produced with circular cross sectional shapes. Other cross sectional shaped fibers such as trilobal, triangular, hollow and pentagonal fibers are also produced to improve some properties of fibers and fabrics such as lustre, handle, wicking rate, strength, stiffness and bulkiness. In this research we aimed to investigate compressional behaviours of fabrics knitted from polypropylene fibers having three different cross sectional shapes; namely circular, trilobal and triangular. Morphological, structural and mechanical properties of produced fibers were evaluated by using scanning electron microscopy, X-ray diffractometry, differential scanning calorimetry and tensile tester, respectively. In terms of structural and mechanical properties, no significant differences were found related to fiber cross sectional shapes. Then, plain knitted farbrics were produced and compressional properties of these fabrics were investigated. Fabrics knitted from trilobal fibers showed the highest compressibility properties and it is followed by fabrics which are produced from triangular and circular fibers.     

The influence of thermal stabilization stage on the molecular structure of polyacrylonitrile fibers prior to the carbonization stage

Structural transformation from a linear chain structure to crosslinked chain structure, occuring during the thermal stabilization stage of carbon fiber manufacture, was followed through the use of infrared spectroscopy, differential scanning calorimetry (DSC), elemental analysis and gel-fraction measurements. The results obtained from the analysis of IR spectroscopy showed the gradual and continuous loss of intensity of the nitrile (C≡N) vibration at 2242 cm⁻¹ closely associated with the cyclization reactions whereas the intensity loss of the methylene (CH₂) groups vibration around 2920–2939 cm⁻¹ has been attributed to the loss of hydrogen atoms as part of the dehydrogenation reactions. The dehydrogenation index, evaluated using the absorbance ratio of A₁₄₅₂/A₁₃₆₈, also indicated the gradual loss of hydrogens in agreement with decreasing hydrogen content with progressing stabilization process. IR spectroscopy also showed the emergence of new absorption bands attributed to the formation of crosslinked ladder-like structure in the 1590–1600 cm⁻¹ region. The amount of newly formed crosslinked structure was characterized using DSC conversion index, IR conversion index and gel-fraction measurements. The results are compared and discussed in detail.     

Effects of Root Plant Growth Promoting Rhizobacteria Inoculations on the Growth and Nutrient Content of Grapevine

The objective of this study was to evaluate the effects of seven nitrogen (N₂)-fixing and/or phosphorus (P)-solubilizing and siderophore-producing microorganism based bio-fertilizers in single and triple strain combinations isolated from the acidic rhizospheric soil of native tea, grapevine, and wild red raspberries. As a result of this study, bacterial efficiency was found to be variable and depended on the bacterial strains and evaluated growth parameters. Plant growth-promoting rhizobacteria (PGPR) has improved macro- and micro-nutrient concentrations in grapevine leaves, and stimulated plant growth. Triple inoculation and single inoculation based bio fertilizers were found to stimulate overall plant growth, including shoot and leaf weight, main shoot length, leaf ground index, chlorophyll, nitrogen, zinc and iron content of grapevine cv ‘Italy’. Bio-fertilizers increased the nutrients such as nitrogen, zinc and iron concentrations and consequently increased the chlorophyll content of the leaves.     

Effect of irrigation amounts applied with subsurface drip irrigation on corn evapotranspiration, yield, water use efficiency, and dry matter production in a semiarid climate

Quantifying the local crop response to irrigation is important for establishing adequate irrigation management strategies. This study evaluated the effect of irrigation applied with subsurface drip irrigation on field corn (Zea mays L.) evapotranspiration (ETc), yield, water use efficiencies (WUE = yield/ETc, and IWUE = yield/irrigation), and dry matter production in the semiarid climate of west central Nebraska. Eight treatments were imposed with irrigation amounts ranging from 53 to 356 mm in 2005 and from 22 to 226 mm in 2006. A soil water balance approach (based on FAO-56) was used to estimate daily soil water and ETc. Treatments resulted in seasonal ETc of 580–663 mm and 466–656 mm in 2005 and 2006, respectively. Yields among treatments differed by as much as 22% in 2005 and 52% in 2006. In both seasons, irrigation significantly affected yields, which increased with irrigation up to a point where irrigation became excessive. Distinct relationships were obtained each season. Yields increased linearly with seasonal ETc (R² = 0.89) and ETc/ETp (R² = 0.87) (ETp = ETc with no water stress). The yield response factor (ky), which indicates the relative reduction in yield to relative reduction in ETc, averaged 1.58 over the two seasons. WUE increased non-linearly with seasonal ETc and with yield. WUE was more sensitive to irrigation during the drier 2006 season, compared with 2005. Both seasons, IWUE decreased sharply with irrigation. Irrigation significantly affected dry matter production and partitioning into the different plant components (grain, cob, and stover). On average, the grain accounted for the majority of the above-ground plant dry mass (≈59%), followed by the stover (≈33%) and the cob (≈8%). The dry mass of the plant and that of each plant component tended to increase with seasonal ETc. The good relationships obtained in the study between crop performance indicators and seasonal ETc demonstrate that accurate estimates of ETc on a daily and seasonal basis can be valuable for making tactical in-season irrigation management decisions and for strategic irrigation planning and management.