Pharmacokinetics and tissue disposition of meloxicam in beef calves after repeated oral administration.

The objective of this study was to investigate the pharmacokinetics and tissue disposition of meloxicam after repeated oral administration in calves. Thirteen male British × Continental beef calves aged 4 to 6 months and weighing 297-392 kg received 0.5 mg/kg meloxicam per os once daily for 4 days. Plasma meloxicam concentrations were determined in 8 calves over 6 days after first treatment. Calves were randomly assigned to be euthanized at 5, 10, 15 (n = 3/timepoint), and 19 days (n = 4) after final administration. Meloxicam concentrations were determined in plasma (LOQ= 0.025 µg/mL) and muscle, liver, kidney, and fat samples (LOQ = 2 ng/g) after extraction using validated LC-MS-MS methods. The mean (± SD) Cmax , Cmin , and Caverage plasma meloxicam concentrations were 4.52 ± 0.87 µg/mL, 2.95 ± 0.77 µg/mL, and 3.84 ± 0.81 µg/mL, respectively. Mean (± SD) tissue meloxicam concentrations were highest in liver (226.67 ± 118.16 ng/g) and kidney samples (52.73 ± 39.01 ng/g) at 5 days after final treatment. Meloxicam concentrations were below the LOQ in all tissues at 15 days after treatment. These findings suggest that tissue from meloxicam-treated calves will have low residue concentrations by 21 days after repeated oral administration.

The economic cost of farm-related fatalities in Australia.

Farm-related fatalities are a significant problem in Australian agriculture. Over the period 2001-2004, there were 404 fatalities that occurred as a direct consequence of visiting, residing, or working on a farm. This study employed a human capital approach to establish the economic costs of farm-related fatalities to the Australian economy. Modeling of direct and indirect costs associated with farm-related fatalities estimated that the 404 traumatic deaths over the period 2001-2004 cost the Australian economy $650.6 million in 2008 Australian dollars (AUD). This equates to 2.7% of the 2008 farm gross domestic product (GDP) due to potentially preventable farm accidents and injuries. Farm-related deaths are a significant economic cost to the Australian economy. Greater resources need to be directed to farm health and safety interventions to increase their effectiveness at reducing the risk exposure of those visiting, residing, and working on Australian farms.

Australian farm work injuries: incidence, diversity and personal risk factors.

Information on farm work-related injuries was sought to assist in the design of effective farm safety prevention programs. A telephone survey was conducted using a stratified random sample of 919 sheep/wool, beef cattle and dryland broadacre cropping farms from three shires in the wheat/sheep belt of New South Wales. The adjusted response rate was 84%. There were 425 reported injuries over an 18-month period. One in five farms reported at least one injury per year, while one in 12 farms reported at least one serious injury per year. Animal-related injuries were the largest major category for agent of injury, while the largest category for nature of injury was sprain and strain, recording almost one-quarter of all injuries. The farm workshop or shed was the most common location of injury, with more than 20% of all reported injuries occurring there. Personal risk factors thought to contribute to these farm work-related injuries were examined. The statistically significant personal risk factors for injury occurrence were age (and/or experience), previous injury status, body mass index, hours of sleep, a variable measuring daytime drowsiness and a variable measuring perceived stress.

Iron complexation with oral deferoxamine in a swine model.

A controversial therapy in the management of acute iron poisoning is the oral administration of deferoxamine which purportedly complexes unabsorbed iron, exerts protection at the cellular level, and/or enhances the renal elimination of ingested iron. To study the effects of oral deferoxamine on iron absorption, fasted male pigs weighing an average of 10 kg simulated potentially toxic iron overdoses in 12 to 24-mo-old children. A control group of 13 pigs received 60 mg elemental iron/kg via oral gavage followed by 50 ml of distilled water. Serum iron (SI) levels were obtained at 0, 1 2, 4, 6 and 8 h post-iron dosing. The study group of 10 pigs received 60 mg elemental iron/kg po followed by 10 g deferoxamine (1 g/kg). SI levels were obtained at the same intervals. There was no mortality in either group. Statistical differences in SI were noted at 6 and 8 h. Characteristic urine discoloration secondary to deferoxamine was noted at 4 h in the study group. Deferoxamine reduced some peak 51 levels but did not diminish the total absorption of iron.

Early events in polyomavirus infection: fusion of monopinocytotic vesicles containing virions with mouse kidney cell nuclei.

The entry of polyomavirus enclosed in monopinocytotic vesicles into mouse kidney cell nuclei was studied and evidence for a fusion mechanism was obtained. In vivo studies using the fluorescent lipophilic dye diI-C16(3) as a plasma membrane label showed that polyomavirus-infected nuclei accumulate plasma membrane, while uninfected or polyoma capsid-infected nuclei do not. Further evidence for fusion was obtained with electron microscopy of thin sections of infected mouse kidney cells. These specimens showed accumulation of plasma membrane in the outer nuclear membrane as well as evidence of recent fusion events. The polyoma virions (capsid proteins) were seen to accumulate on the inner nuclear membrane and in the nucleus and were identified by immunogold staining of the thin sections. The combined results of the in vivo dye studies and thin section immunoelectron microscopy studies provide evidence for a fusion mechanism for polyomavirus entry into mouse kidney cell nuclei.

Octyl-beta-D-glucopyranoside extracts polyomavirus receptor moieties from the surfaces of mouse kidney cells.

Polyomavirus receptor moieties were extracted from the surfaces of mouse kidney cells with the nonionic detergent octyl-beta-D-glucopyranoside. Following extraction with this detergent, mouse kidney cells were refractory to polyomavirus infection. Binding studies demonstrated that this loss of susceptibility resulted from extraction of a peripheral membrane protein or proteins required for proper virus attachment to and infection of mouse kidney cells. Infection of extracted mouse kidney cells returned following a 2-h recovery period. However, the presence of cycloheximide or tunicamycin in the recovery media interfered with recovery from infection. Cells could be infected immediately after extraction by supplying them with the extracted moieties prior to or concomitant with infection. A complex of polyomavirus and the extracted receptor protein was formed by in vitro incubation and was stable in sucrose gradient analysis. Functional receptor moieties were prepared in the form of liposomes from the detergent extract. The virus-receptor complex was immunoprecipitated with anti-polyomavirus immunoglobulin G, and the portion of the complex contributed by the cell was identified. Immunoblot analysis of the mouse kidney cell detergent extract with a receptor-specific 125I-labeled anti-idiotypic antibody or 125I-labeled polyomavirus demonstrated several reactive proteins. Attachment of polyomavirus to mouse kidney cells, followed by extraction of the virus-receptor complex, identified polyomavirus-binding proteins similar to those observed in in vitro binding. Proteins with molecular weights of approximately 95,000, 50,000 and 25,000 to 30,000 were consistently observed in all receptor assays. The relationship between these proteins and their possible involvement as the cell receptor for polyomavirus are discussed.

Cross-linking of a polyomavirus attachment protein to its mouse kidney cell receptor.

We used photoaffinity cross-linking with the heterobifunctional cross-linker N-hydroxysuccinimidyl 4-azidobenzoate (HSAB) to covalently link polyomavirus to a mouse kidney cell surface component. The virus-HSAB combination was adsorbed to the cells and then cross-linked and isolated in monopinocytotic vesicles from the cells after endocytosis. The cross-linked product was identified on sodium dodecyl sulfate-polyacrylamide gels by the presence of a new band carrying 125I-labeled virion protein with a higher molecular mass than the normal virion protein bands. A single new band, with an apparent molecular mass of 120 kilodaltons (120 kDa), was identified by this procedure. This band was formed only in the presence of the HSAB cross-linker when virions were bound to the cells. The band also copurified with cross-linked virions when virion-containing vesicles were treated with detergent to remove the cell membrane. Antibody treatments that blocked up to 100% of virus binding and internalization also blocked cross-linking, as measured by the formation of the 120-kDa band. The 120-kDa band was characterized by preparation of antibody against the excised band from the gel. This antibody was shown to have the expected dual specificity for polyomavirus VP1 sequences and plasma membrane proteins, as analyzed on Western blots. The anti-120-kDa antibody was also shown by immunofluorescence to bind to the surface of mouse kidney cells. These data have demonstrated that molecules of possible biological significance in the binding of polyomavirus to mouse kidney cells have been cross-linked and that cell surface molecules have been identified that may be characterized further for possible receptor function in polyomavirus attachment.

Isolation and characterization of monopinocytotic vesicles containing polyomavirus from the cytoplasm of infected mouse kidney cells.

Monopinocytotic vesicles containing polyomavirus were isolated from the cytoplasm of mouse kidney cells infected with polyomavirus using sucrose density gradients. Nonenclosed, membrane-associated virions released by the action of neuraminidase separated from vesicle-enclosed virions in the sucrose gradient. Marker enzyme assays indicated the derivation of the vesicle membrane from the plasma membrane of the cell. The 125I-labeled virus enclosed in the vesicle sedimented more slowly in the gradient and was not observed unless infection and endocytosis had occurred. Detergent treatment of virion-containing vesicles caused the release of polyomavirus with sedimentation properties similar to those of purified polyoma virions. In addition, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of virion proteins from vesicles containing virions demonstrated patterns of proteins similar to those of purified intact virions. Electron microscopy confirmed the presence of single intact virions inside vesicles. The study of these monopinocytotic virion-containing vesicles represents a further step in elucidating the early events of polyomavirus infection.

Tracheal stomal stenosis after laryngectomy.

Stenosis of the postlaryngectomy tracheal stoma remains a persistent problem. A retrospective study of 89 patients determined on overall incidence of 22 percent. The use of postoperative radiotherapy was associated with a higher incidence (36 percent) than preoperative radiotherapy (19 percent) and combined preoperative and postoperative radiotherapy (17 percent). Retention of the tracheal cannula for longer than 1 week was associated with a slightly increased incidence (25 percent) of stenosis. The technique of stomal construction was an important determinant of stoma stenosis. A simple circle of straight transection of the trachea had the highest incidence (29 percent) of stenosis, which could be reduced with a beveled technique (15 percent). The lowest incidence was seen with a primary plastic or flap construction technique (8 percent). The authors recommend the construction of a patulous stoma by a technique of beveling transection of the tracheal stump in combination with the use of interdigitation skin flaps.

Studies on the de novo biosynthesis of NAD in Escherichia coli. The separation of the nadB gene product from the nadA gene product and its purification.

Quinolinic acid (pyridine 2,3-dicarboxylic acid) which is an immediate precursor of the pyridine nucleotides, is synthesised from L-asparate and dihydroxyacetone phosphate in Escherichia coli. Extracts from certain nadB mutants complement the extracts prepared from all nadA mutants for the enzymic synthesis of quinolinate. Using the complementation assay, the quinolinate synthetase B protein has been purified more than 300-fold. The quinolinate synthetase B protein exists in all nadA and nadC mutants examined. The quinolinate synthetase A protein was present in all nadC mutants and most (but not all) nadB mutants. The facile separation of the wild-type quinolinate synthetase A and B proteins out of a nadC mutant suggests that quinolinate synthetase does not exists as a tightly bound complex. The partially purified quinolinate synthetase is inhibited by physiological concetrations of NAD and NADH but not by NADP or NADPH.