Phenylbutazone in the horse: a review

Phenylbutazone is an acidic, lipophilic, non-steroidal anti-inflammatory drug (NSAID). It is extensively metabolized in the horse. The metabolites so far identified, oxyphenbutazone, gamma-hydroxyoxyphenbutazone, account for some 25-30% of administered dose over 24 h. The plasma half-life of phenylbutazone and termination of its pharmacological action are determined primarily by its rate of hepatic metabolism. Phenylbutazone acts by inhibiting the cyclooxygenase enzyme system, which is responsible for synthesis of prostanoids such as PGE2. It appears to act on prostaglandin-H synthase and prostacyclin synthase, after conversion by prostaglandin-H synthase to reactive intermediates. It markedly reduces prostanoid-dependent swelling, edema, erythema, and hypersensitivity to pain in inflamed tissues. Its principal use in the horse is for treatment of soft tissue inflammation. Phenylbutazone is highly bound (greater than 98%) to plasma protein. After i.v. injection, blood levels decline with an elimination half-life of 3-10 h. The plasma kinetics of phenylbutazone may be dose dependent, with the plasma half-life increasing as the drug dosage level increases. Plasma residues of the drug at 24 h after a single i.v. dose of 2 g/450 kg average about 0.9 microgram/ml, but considerable variation occurs. If dosing is repeated, the plasma residue accumulates to give mean residual blood levels of approximately 4.5 microgram/ml on Day 5 after 4 days of dosing. Approximately similar blood levels are found after a combination of oral and i.v. dosing. Experiments on large numbers of horses in training have been undertaken to ascertain the population distributions of residual blood levels after such dosing schedules. Absorption of phenylbutazone from the gastrointestinal tract is influenced by the dose administered and the relationship of dosing to feeding. Access to hay can delay the time of peak plasma concentration to 18 h or longer. Under optimal conditions, the bioavailability of oral phenylbutazone is probably in the region of 70%. Paste preparations may be more slowly absorbed than other preparations and yield higher residual plasma levels at 24 h after dosing, but further controlled studies are required. Phenylbutazone is easily detected in the plasma and urine of horses but concentrations in saliva are low. It is quantitated for forensic purposes by HPLC. The variability of this method between laboratories is about +/- 25%. Increasing urinary pH increases the urinary concentration of phenylbutazone and its metabolites up to 200-fold.(ABSTRACT TRUNCATED AT 400 WORDS)     

Comparative aspects of glaucoma

Glaucoma is a term used to indicate a rise of intra-ocular pressure. Primary glaucomas caused by mechanical obstruction of the outflow channels or by degenerative changes within them are rare in animals but common in man. Glaucoma secondary to intra-ocular disease is equally common in primates and lower animals. Glaucoma in animals normally presents with an enlarged painful eye whose cornea is cloudy; similar to congenital glaucoma in man. However, the adult human sclera and cornea are much thicker and will not expand so readily with the raised intraocular pressure. As a consequence the optic nerve becomes damaged insidiously and blindness from glaucoma without symptoms is therefore much more common in man than in animals. Treatment is easier in man because of the powerful ciliary muscle inserted into the trabecular meshwork. The consequent presence of the canal of Schlemm, the thickness of the sclera and the avascularity of the iris, make surgery in man easier and more satisfactory. Résumé. Le glaucome désigne un état dû à l'augmentation de la tension intra-oculaire. Les glaucomes primaires, provoqués par une obstruction mécanique des canaux excréteurs ou par des modifications dégénératives à ce niveau, sont rares chez les animaux mais fréquents chez l'homme. Le glaucome secondaire à une affection intra-oculaire est également fréquent chez les primates et les animaux inférieurs. Le tableau clinique du glaucome chez l'animal, se manifestant par un æil augmenté de volume et douloureux, et une cornée partiellement opacifiée, s'observe uniquement au cours du glaucome congénital de l'homme; cet aspect est dû à un épaississement de la sclérotique et de la cornée qui ne se laissent pas facilement distendre par une tension intra-oculaire augmentée; les lésions du nerf optique consécutives semblent être plus fréquentes chez l'homme que chez les animaux. Le traitement est plus facile dans l'espèce humaine, grâce à l'existence du muscle ciliaire trés puissant, qui s'insère dans le reticulum trabeculaire. La présence du canal de Schlemm, l'épais-seur de la sclérotique et l'absence de vascularisation de l'iris font que]'intervention chirurgicale est plus facile et donne des résultats plus satisfaisants chez l'homme. Zusammenfassung. Der Ausdruck Glaucom wird zur Bezeichnung der Steigerung des intra-okularen Drucks verwendet. Primäre Glaucome, die durch mechanisch bedingte venöse Stauung oder durch degenerative Veränderungen in den Wirbelvenen verursacht werden, sind bei Tieren selten, aber beim Menschen häufig. Sekundär nach intraokularen Erkrankungen auftretende Glaucome sind gleich häufig bei Primaten und niederen Tieren. Das klinische Auftreten des Glaucoms bei Tieren, eines vergrösserten, schmerzhaften Auges mit Trübung der Cornea, ist nur bei angeborenem Zustand zu bemerken, weil Sklera und Cornea viel dicker sind und sich nicht so leicht mit steigendem untraokularen Druck ausdehnen. Deshalb ist die Sehnervenschadigung beim Menschen wahrscheinlich häufiger als bei Tieren. Die Behandlung ist bei Menschen infolge des in das Trabecularnetz eingebetteten kräftigen Ziliarmuskels leichter. Das Vorhandensein des Schlemmschen Kanals, die Dicke der Sklera und die Gefässlosigkeit der Iris ermoglichen beim Menschen leichtere chirurgische Eingriffe mit zufriedenstellenderen Ergebnissen.     

Responses of otebo bean (Phaseolus vulgaris L.) to postemergence herbicides

Ontario otebo bean growers have few herbicide options available for weed management. Six field trials were conducted in Ontario, Canada, over a 2 year period (2003 and 2004) to evaluate the tolerance of otebo bean to the postemergence (POST) application of bentazon at 1080 and 2160 g ai ha⁻¹, fomesafen at 240 and 480 g ai ha⁻¹, sethoxydim at 500 and 1000 g ai ha⁻¹, quizalofop-p-ethyl at 72 and 144 g ai ha⁻¹, imazamox plus fomesafen at 25 + 200 and 50 + 400 g ai ha⁻¹, and imazamox plus bentazon at 25 + 600 and 50 + 1200 g ai ha⁻¹. All treatments, including the untreated control, were maintained weed-free during the growing season. The POST application of bentazon, imazamox plus fomesafen, and imazamox plus bentazon caused as much as 9% visual injury and reduced the plant height ≤ 12%, reduced the shoot dry weight ≤ 32%, and delayed maturity but had no adverse effect on the yield of otebo bean. Fomesafen, sethoxydim, and quizalofop-p-ethyl applied POST caused as much as 8% visual injury but this was transient and had no adverse effect on the plant height, shoot dry weight, seed moisture content, and yield of otebo bean, except for quizalofop-p-ethyl, which reduced the shoot dry weight as much as 18%. Based on these results, bentazon, fomesafen, sethoxydim, quizalofop-p-ethyl, imazamox plus fomesafen, and imazamox plus bentazon applied POST have an adequate margin of crop safety for weed management in otebo bean production in Ontario. However, care must be taken to avoid spray overlaps to prevent injury from bentazon, imazamox plus fomesafen, and imazamox plus bentazon.     

The Effect of Drying Quercus robur Acorns to Different Moisture Contents, followed by Storage, either with or without Imbibition

Freshly harvested Quercus robur acorns were spread out, twodeep, in trays, and dried/stored (at +2°C over the courseof 28 weeks) to either 45, 40, 35, 30 or 25 per cent moisturecontent (fresh weight basis). Drying/storage significantly reducedthe germination percentage (P< 0.01). The acorns at eachmoisture content were then either ‘soaked’ or ‘notsoaked’, before immediate germination; or returned tothe same cold store at +2°C, this time in loosely tied polythenebags. Soaking raised the acorns moisture content (M.C.), andalso brought about a significant increase in germination capacity(P<0.01). Regardless of the moisture content immediatelybefore soaking, "soaked" acorns in loosely tied polythene bagsstored better than ‘unsoaked’ acorns. All ‘bagged’acorns (whether ‘soaked’ or ‘unsoaked’)stored better than acorns dried/stored in open trays.     

Vertical distributions of Japanese sardine (Sardinops melanostictus) eggs: comparison of observations and a wind-forced Lagrangian mixing model

To understand how Japanese sardine eggs vertically disperse in water, we acquired a series of depth‐resolved samples of eggs while tracking a drogued buoy to follow the water mass in which the eggs were spawned. This survey was conducted in early March of 1991, when the sardine population was abundant and actively spawning in the Pacific off Kyushu. Buoyancy of the eggs was estimated by measuring the specific gravity, and was 1–4 × 10^?3 less than that of the water in which they were spawned, giving a rising speed of 1–2 mm s^?1. In an attempt to diagnose the dynamics underlying the observed vertical profiles of the eggs, a one‐dimensional egg distribution model incorporating the egg rising speed and wind‐ and depth‐dependent vertical diffusivity was formulated. Observed eggs were mainly in the surface mixed layer, and their vertical distribution changed with wind‐induced surface mixing: during strong winds, the eggs were distributed relatively evenly over the upper 60–75 m, whereas during weak winds and shallow pycnocline, the eggs formed a subsurface peak around 25 m depth. The model accurately reproduced these variations in the vertical distributions of eggs, suggesting that the gradients of egg concentration are sensitive to the strength of wind and the structure of underlying hydrography. Further tests with the model showed the importance of positive buoyancy: neutrally buoyant eggs formed subsurface maxima below the food‐rich euphotic zone. The balance of vertical mixing and floating, which allows the eggs to remain in the euphotic zone but away from the near‐surface waters, may be an adaptation to minimize surface‐enhanced predation, while allowing the eggs to hatch in the food‐rich euphotic zone.     

Striped marlin (Tetrapturus audax) movements and habitat utilization during a summer and autumn in the Southwest Pacific Ocean

Six striped marlin (Tetrapturus audax) were caught on hook and line from recreational fishing boats near northern New Zealand (34°S, 174°E) and tagged and released with pop‐off satellite archival tags. For periods ranging from 22 to 60 days over the geographical range 168°E–170°W and 13–34°S, five tags collected a total of 202 days (range of 21–60 days) of data. These data permit the investigation of striped marlin geographical and vertical movements and water temperatures occupied from February to June 2003. One hundred and one days of geoposition data showed a preliminary view of their movements in and around New Zealand waters. Transmitted temperature and depth data indicated striped marlin spent 80% (±2%) of their time in the mixed layer including 72% (±2%) of their time in the top 5 m. Temperature data indicated 75% (±10%) of the striped marlin’s time was spent in water temperatures between 20.1 and 24.0°C. Tagged striped marlin moved faster during periods of directed movement away from New Zealand versus periods of passive movements when the fish were proximal to New Zealand or not moving in any specific direction. These data support some existing hypotheses about striped marlin physiological ecology and allow preliminary suggestions about how striped marlin bycatch might be reduced.     

White bean (Phaseolus vulgaris) tolerance to preplant-incorporated herbicides

There is a limited number of registered herbicides in white beans. Field trials were conducted at two Ontario, Canada, locations (Exeter and Ridgetown) in 2001 and 2002 to evaluate tolerance of two white bean cultivars, AC Compass and OAC Thunder, to preplant-incorporated applications of S -metolachlor plus imazethapyr (1600 + 75 and 3200 + 150 g ai ha⁻¹, respectively), flumetsulam plus S -metolachlor ( premixed at 1443 and 2886 g ai ha⁻¹) and cloransulam-methyl (35 and 70 g ai ha⁻¹). There were no differences between the two cultivars in their responses to the herbicide treatments. S -metolachlor plus imazethapyr caused as much as 5% visual crop injury and decreased plant height up to 20%, shoot dry weight up to 39% and yield as much as 21%. Flumetsulam plus S -metolachlor caused as much as 7% visual crop injury and reduced plant height by up to 25%, shoot dry weight by up to 46% and yield as much as 24%. Cloransulam-methyl caused as much as 10% visual crop injury and decreased plant height up to 35%, shoot dry weight up to 55% and yield as much as 44%. There were no differences in seed moisture content among any of the herbicide treatments. This research suggests that the margin of safety of white bean is inadequate to support the preplant-incorporated registration of S -metolachlor plus imazethapyr, flumetsulam plus S -metolachlor and cloransulam-methyl in Ontario.