Pharmacokinetics of ciprofloxacin in sheep after single intravenous or intramuscular administration

Summary

The disposition and urinary excretion of ciprofloxacin (CIP) following intravenous (IV) or intramuscular (IM) administration of 7.5 mg/kg body weight in sheep (n = 5) was studied. The intravenous plasma concentration curve was best described pharmacokinetically by a two‐compartment open model, while the intramuscular administration data fitted better to a one‐compartment open model. Mean elimination half‐lives after IV and IM administration were 72 and 184 minutes, respectively. The absorption of intramuscularly administered CIP in sheep was fast: maximal plasma concentration (Cmax) was reached quickly (tmax 31.93 min) and attained values of 0.69 ± 0.27 mg/l. The bioavailability was 49%. The urinary data showed a significant decrease in the elimination rate constant of CIP when CIP was administered intramuscularly. The other parameters calculated did not display differences between the two routes of administration. The results obtained suggest that when CIP was administered by the IM route in the assayed dose, it was able to maintain serum concentrations above the MIC of most common pathogens over an 8‐hour period.     

The presence of double-stranded RNAs in <Emphasis Type="Italic">Alternaria alternata</Emphasis> Japanese pear pathotype is associated with morphological changes

Strains of the Japanese pear pathotype of Alternaria alternata were screened for double-stranded RNAs (dsRNAs). Four strains had several dsRNAs; strain N18 was associated with several dsRNAs and had impaired growth phenotypes such as irregular mycelium and abnormal pigmentation. We isolated dsRNA-cured isolates from strain N18 by single-conidium isolation. The dsRNA-cured isolates had recovered normal growth and pigmentation. Enlarged vesicles were observed in mycelial cells of the original dsRNA-carrying N18 strain. DAPI nuclear staining revealed regression of the nuclei in dsRNA-carrying N18 cells. These results indicate that the dsRNAs might have negative effects, such as apoptosis-like cell death, on the host fungus.     

Soybean cultivar performance in the presence of soybean Asian rust,in relation to chemical control programs

Soybean rust is caused by an obligate parasite (Phakopsora pachyrhizi) which has spread in Brazil in each new season since 2001 and, despite the efforts to control the disease, losses have occurred every year. Its control demands several tactics amongst which chemical control with fungicides is the main method and remains indispensable. Control strategies such as the use of cultivars with partial resistance are desirable, but are not yet commercially available. The present study analyzed the existing differences in the reactions of short, medium and long cycle soybean cultivars against Asian rust and their responses to fungicide sprays. The experiment was conducted at Uberlandia-MG, Brazil, under field conditions from December 2007 to May 2008, in the Syngenta Seeds Experimental Station. The high pressure of the disease in the experiment simulated the natural pressure that the disease often reaches in Brazil. The studied variables were: visual severity (percentage of infected leaf area), percentage defoliation and productivity (kg ha⁻¹). Disease severity was expressed as AUDPC (area under disease progress curve). Variance analysis and comparison of means by the Tukey test (5% significance) were done for all variables studied. Significant differences were observed between cultivar effects and chemical control programs. The results obtained here indicate that the cultivars M-Soy 8199RR and Emgopa 315RR were less susceptible to disease, and that a control program termed “monitoring” (in which the appearance of new pustules of the pathogen were monitored to make the decision at each fungicide spray) was the most effective.     

A molecular mechanism of resistance to streptomycin in <Emphasis Type="Italic">Xanthomonas oryzae</Emphasis> pv. <Emphasis Type="Italic">oryzicola</Emphasis>

Xanthomonas oryzae pv. oryzicola, the causal agent of rice leaf streak disease, was found to be sensitive to streptomycin (an aminocyclitol glycoside antibiotic), by inhibition of protein synthesis resulting from interference with translational proofreading. This study aimed to determine the molecular resistance mechanism of X. oryzae pv. oryzicola to streptomycin. Seven streptomycin-resistant mutants were obtained by UV induction or streptomycin selection. These mutants can grow at 100 μg ml⁻¹ of streptomycin while the wild-type strain (RS105) cannot grow at 5 μg ml⁻¹. Sequencing indicated that the rpsL gene encoding ribosomal protein S12 has 375 bp encoding 125 amino acid residues. In all resistant strains, a mutation in which AAG was substituted for AGG (Lys→Arg) occurred either at codon 43 or 88. Two plasmids, pUFRRS and pUFRRX, were constructed by ligating the rpsL gene into the cosmid pUFR034. The plasmids pUFRRS and pUFRRX containing the Lys→Arg mutation of the rpsL gene conferred streptomycin resistance to the sensitive wild-type strain by electroporation. Both transformants, RS1 and RS2, could grow in the medium containing 50 μg ml⁻¹ of streptomycin. A mutation at codon 43 or 88 in rpsL can result in resistance of Xanthomonas oryzae pv. oryzicola to streptomycin.     

Identification of a periorbital wooden foreign body as the cause of chronic ocular discharge in a horse

The clinical, diagnostic and therapeutic features of a horse with a wooden foreign body embedded in the deep portion of the right masseter muscle adjacent to the right orbit are presented. The purpose of this report is to describe the clinical presentation, magnetic resonance imaging findings and treatment of a penetrating wooden foreign body in a horse that had no history of trauma or evidence of a puncture wound. This report documents the usefulness of magnetic resonance imaging to detect a wooden foreign body embedded in the soft tissues of a horse with a chronic copious ocular discharge. Two surgical procedures were necessary, which is a frequent complication encountered with wooden foreign bodies.     

Progesterone supplementation during multiple ovulation treatment in buffalo species (<Emphasis Type="Italic">Bubalus bubalis</Emphasis>)

The aim of this study was to evaluate the effect of exogenous progesterone supplementation on superovulatory response in buffaloes that has undergone a multiple ovulation program. Fourteen Mediterranean buffaloes were divided into two groups and received a 4-day decreasing dosage of an equal mixture of 500 IU of FSH and LH starting on day 8 of the cycle. In group A (n = 7) a progesterone-releasing intravaginal device was removed on day 8, whereas in group B (n = 7) it was left till day 10, when PGF_2a {\hbox{PG}}{{\hbox{F}}_{{2}\alpha }} was administered. Eighty hours later, buffaloes were artificially inseminated and after 6 days they undergone uterine flushing. A higher (P < 0.05) number of corpora lutea (8.3 vs. 5.7) and embryo/flushing/buffalo (2.3 vs. 1.3) were recorded in group B vs. group A if responsive buffaloes are considered (n = 12) and the number of corpora lutea was highly correlated with the number of embryos (r = 0.65; P < 0.05). In conclusion, progesterone supplementation during the first 2 days of the superovulation treatment seems to enhance the recovery rate in buffalo species. A high ovulation rate, associated with a high number of corpora lutea, can represent a parameter for estimating embryo recovery.     

Temporal changes in endogenous estrogens and expression of behaviors associated with estrus during the periovulaory period in Murrah buffaloes (<Emphasis Type="Italic">Bubalus bubalis</Emphasis>)

The objective of this study were (1) to establish the duration of behavioral estrus signs and timing of ovulation in Murrah buffaloes (n = 10) and (2) to determine relationship between behavioral estrus signs with change in plasma estrogen concentrations. Estrus and its behavioral signs were detected at hourly intervals by visual observations, per recta examination of genitalia and bull parading four times in a day for 30 minutes each. Among the behavioral signs of estrus, swollen vulva (80%) was the best indicator of estrus followed by excitement (70%). Among the duration of behavioral estrus signs the first and longest duration of estrus signs was swollen vulva which was seen upto 19.8 ± 0.8 h after onset of estrus. The mean total duration of estrus symptoms from appearance to disappearance of all the behavioral estrus symptoms was 23.5 ± 1.7 h. All the behavioral estrus symptoms were observed during the period of estrogen surge. Endocrine profile during the periestrus period showed that the mean peak concentrations of total estrogen 23.9 ± 3.9 pg/ml occurred at 8.8 ± 1.7 h after onset of estrus. The average number of estrus symptoms observed per animal during onset of spontaneous estrus was 5.7. Ovulation occurred after 37.4 ± 1.7 h after onset of estrus and 13.4 ± 1.0 h after end of total estrogen surge respectively. In conclusion, our results suggest that all signs of behavioral estrus occurred during the preovulatory rise in estrogens. The first sign of estrus to be observed was a swollen vulva and this symptom persisted the longest.     

Identification and pathogenicity of Neophysopella species associated with Asian grapevine leaf rust in Brazil

Asian grapevine leaf rust (AGLR) causes severe crop losses in Brazilian viticulture, mainly in latitudes <25°S. The purpose of this study was to identify the pathogen(s) involved with AGLR in Brazil, based on phylogenetic and morphological analysis and pathogenicity tests. In total, 56 monouredinial isolates from six Brazilian states were identified using the internal transcribed spacer 2 and the large subunit rRNA gene D1/D2 regions. All 50 isolates from the south-central region were classified as Neophysopella tropicalis, and the other six isolates from the north-east region as Neophysopella meliosmae-myrianthae. This result provides evidence that two pathogen introductions from different sources may have occurred in the country. For both species, paraphyses were cylindrical, incurved, aseptate, and hyaline, while urediniospores were short-pedicellate, obovoid or obovoid-ellipsoid, with the wall colourless or pale yellowish, evenly echinulate. Representative isolates from both species caused typical AGLR symptoms on Vitis vinifera 'Merlot' and V. labrusca 'Niagara Rosada'. Overall, regardless of the Neophysopella species, isolates caused similar leaf disease severities. Higher disease severity was observed in Niagara Rosada (average of 40.3% of diseased leaf area) compared to Merlot (20.5%). This study reports, for the first time, the characterization of Neophysopella species associated with AGLR in Brazil.