Microvascular anastomoses. A comparative study of fibrinogen adhesive and interrupted suture techniques.

A modified sleeve technique was developed for making microsurgical anastomoses using a commercially produced fibrinogen adhesive called Tisseel. A controlled study was then carried out to compare the new fibrinogen adhesive anastomoses with conventional suture anastomoses in a bilateral groin flap model using 50 consecutive rabbits. Statistical analysis of the results indicated that flap survival rate and vascular patency rate were comparable for the two techniques. The fibrinogen adhesive anastomoses took less time to complete and, subjectively, were less difficult technically. The suture anastomoses were more versatile. Histologic studies revealed that the adhesive did not flow through the sleeve into the lumen, and that, although there was a brief inflammatory response associated with healing, this inflammation was very localized and did not involve the inner layers of the vessel wall or lumen. It was concluded that the new technique was a useful addition to techniques already available.

Comparison of corneal epithelial wound healing after photorefractive and lamellar keratectomy.

BACKGROUND: The rate of corneal epithelial wound healing may be determined, in part, by the characteristics of the stromal surface. The excimer laser has the ability to produce a highly uniform ablated surface, which may facilitate reepithelialization after photorefractive keratectomy (PRK). METHODS: The rate of corneal epithelial wound healing after excimer laser PRK was compared with the rate of reepithelialization after manual lamellar keratectomy. Ten rabbits received a 4-mm diameter ablation in one eye (fluence = 160 mJ/cm2) and a shallow, 5-mm diameter, manual lamellar keratectomy in the contralateral eye. At 0, 4, 8, 12, 24, 36, 48, 60, and 72 hours after wounding, sodium fluorescein was instilled, and photographs were taken, converted to video images, and digitized. Wound area was calculated for each time point and converted to wound radius; the slopes of the wound radius, plotted over time, were compared to determine rates of healing. Scanning electron microscopy was performed immediately after wounding to examine surface regularity. RESULTS: By 24 hours after wounding, corneas that had undergone PRK demonstrated a significantly faster rate of epithelial wound healing compared with eyes that underwent lamellar keratectomy (33.4 +/- 1.9 microns/hr vs 27.8 +/- 1.4 microns/hr, respectively, for 12 to 72 hours) (p < 0.0001). Scanning electron microscopy showed greater stromal surface irregularity in the corneas that had undergone lamellar keratectomy, compared with the laser-ablated corneas. CONCLUSIONS: This study demonstrates that the rate of epithelial wound healing is significantly faster after excimer laser PRK than after lamellar keratectomy in the rabbit. Variations in surface regularity and wound edge profile may contribute to differences in wound healing.

Treatment and pathogenesis of navicular disease ('syndrome') in horses.

The future directions of navicular disease research are unclear. Often researchers investigate only one of the multitude of factors likely to be important in understanding the disease. Two exceptions to this is work done by Wright in this issue of EVJ and by MacGregor (1988) who compared a number of the treatment regimens (e.g. rest, warfarin, isoxsuprine, shoeing with egg bars) and found that approximately 75% of the horses improved in their performance. Perhaps this percentage of 'recovered' horses from this disease is what can be realistically expected, as often horses with navicular disease remain undiagnosed until the disease has advanced to the stage where problems exist in the foot or to where the conformation-balance of the hoof is irrecoverable. Perhaps the key to controlling the disease is prevention by maintaining good overall hoof husbandry in a conservative and consistent manner. I would advocate that efforts be made to evaluate hoof 'balance' and the validity of the hoof wall-pastern axis being parallel, as these are clearly of importance in this debilitating disease.

Computer-assisted three-dimensional gait analysis of amphotericin-induced carpal lameness in horses.

Motion of 6 clinically sound horses trotting at a speed of 4 m/s on a treadmill was captured by video cameras before and 9, 16, and 23 days after amphotericin-induced lameness to determine the quantitative variables of three-dimensional computer-assisted image analysis that objectively describe carpal lameness. Amphotericin-B was used to induce lameness, and phenylbutazone (2.2 mg/kg of body weight, PO, once) and butorphanol tartrate (0.1 mg/kg IM, q 6 h, to effect) were used to control discomfort. Four 60-Hz cameras were symmetrically placed around the treadmill to capture 6 seconds of images from retro-reflective spheres taped to the trotting horses. Images were transferred to a video-based digitizer and a computer work station, where 4 files of two-dimensional data were reduced to 1 file of three-dimensional data. The effect of lameness on motion analyzed was assessed by use of two-way ANOVA. Differences between means were assessed, using the Student-Newman-Keul's test (P < or = 0.05). Head and withers excursions, (dorsal vertical displacement of head and withers targets, respectively) during the sound forelimb support phase were increased significantly during all lameness measurement periods. Head excursion, but not withers excursion, during the lame forelimb support phase, was decreased significantly during all lameness measurement periods. Computer determinations of stride length swing phase, stance phase, forelimb abduction, and carpal and fetlock ranges of motion did not consistently characterize the lameness. It was concluded that three-dimensional computer-assisted image analysis could be used for objective lameness evaluation in horses and that head and withers excursions were the most consistent variables for assessing equine carpal lameness.

Structural changes in intercellular junctions during keratinization of the stratum medium of the equine hoof wall.

Cells of the intertubular horn of the stratum medium of the equine hoof wall are joined by three types of junctions. Desmosomes and gap junctions were present in all strata. Septate-like junctions and an intercellular line were seen in the distal stratum spinosum subsequent to extrusion of the contents of membrane-coating granules. At a later stage of keratinization, non-membrane-bound acid phosphatase reaction product appeared to leak into the intercellular space except into areas occupied by septate-like junctions and the intercellular line. It is proposed that the formation of septate-like junctions and the intercellular line prior to leakage of acid phosphatase into the intercellular space created stable areas of intercellular adhesion between fully keratinized cells.

A macroscopic study of the vascular system of the bovine hind limb claw.

The vascular organisation of the hind limb claws from clinically normal cattle was studied using plastic corrosion casts. The proper digital artery ran dorsodistally within the interdigital space and gave off a bulbar branch to the bulb, a plantar branch to the axial aspect of the wall and sole, and a coronary artery to the coronary margin and proximal wall. The artery entered the distal phalanx at the axial foramen, coursed through the nutrient canal as the terminal arch, and emerged at the abaxial foramen to anastomose with branches of the bulbar artery. During its interosseous course, the terminal branch gave off 6-8 primary branches which provided the arterial supply to the coronary margin, axial and abaxial wall, white zone and sole. The dorsal proper digital vein and axial and abaxial proper plantar digital veins drained all venous blood from the claw. Each of these large veins arose from numerous smaller veins which joined to form the venous networks of the coronary margin, wall, sole and bulb. A large arched vein passed through the coronary cushion and formed a connection between the superficial coronary venous plexus and the intra-osseous plexus of the distal phalanx. The axial and abaxial proper plantar digital veins were connected by a vessel through the bulbar cushion. At the same level, the axial proper plantar digital veins of the lateral and medial claw were connected to each other by a large vessel through the interdigital space, situated just proximal to the distal interdigital ligaments. This resulted in the presence of a complete distal venous arch along the plantar aspects of both claws. The parietal collecting veins drained most of the venous blood from the sole, white zone and wall, and connected directly to the venous plexuses of the coronary margin and bulb. Valves occurred commonly in medium and larger calibre veins throughout the claw.

A scanning electron microscopic study of the vascular system of the bovine hind limb claw.

The vascular organisation of the hind limb claws of clinically normal cattle was studied using scanning electron micrographs of plastic corrosion casts. The microvasculature of the dermal papillae and lamellae was demonstrated. A consistent vascular pattern was observed in the dermal papillae of the periople, coronary margin, sole and bulb. Ultrastructurally, the papillar vasculature consisted of a central artery and vein surrounded by a fine network of interconnected capillaries and venules. Arteriovenous anastomoses, connecting the central artery and vein, and peripherally situated arteriovenous loops were recognised in the terminal papillae of the white zone only. Arteriovenous anastomoses, focal enlargements and distension of the capillary bed were located within the interior half of the dermal lamellae. Numerous arteriovenous anastomoses were present throughout the entire dermis of the claw and were situated predominantly at the base of the dermal papillae and lamellae. The anastomoses and focal capillary enlargements may influence the blood flow in normal conditions and may play a significant role in the pathophysiology of bovine laminitis and sole ulceration.

Stimulated anti-Stokes Raman scattering in microdroplets.

Stimulated anti-Stokes Raman scattering (SARS) generated by one input beam is observed from CCI(4), ethanol, and water droplets. The first-order SARS intensity is approximately 10(4) times lower than the first-order stimulated-Raman-scattering (SRS) intensity for ethanol droplets. Simultaneous detection of SARS and SRS for water droplets shows an occasional lack of correlation between the SARS and SRS spectra.

Experimental cutaneous free flap transfers in the horse.

Equine limb wounds often heal slowly by epithelialization, and large scars are a frequent end result. In some ways, they resemble the wound associated with human tibial injuries. The literature indicates that previous investigators have failed to transfer free skin flaps successfully in the horse. In this paper, we review our experimental work with the deep circumflex iliac flap in the horse. Dissections of 20 cadavers confirmed the anatomical consistency of the flap. Four flaps survived well when elevated as island flaps, but five orthotopic and nine heterotopic free flap transfers all failed. The cause of failure is still unknown, but our experiments suggested that the horse must be highly susceptible to ischemic reperfusion injury.

Identification of a free skin flap from the region vascularized by the deep circumflex iliac artery of horses.

Areas of skin vascularized by large axial vessels potentially suitable for microvascular anastomosis were investigated in 10 horse cadavers. Eleven such areas were dissected, and the skin over the flank region vascularized by the deep circumflex iliac artery was most suitable. The anatomy of this area was further defined, using angiography and latex injection studies on 10 cadavers.

Longitudinal growth analysis of horses following limited and ad libitum feeding.

Eighteen colts were assigned to one of two groups: limit or ad libitum feeding. Three periods were evaluated: 1) six to 12 months, 2) 12 to 18 months and 3) 18 to 24 months of age. At 24 months of age, ad libitum fed horses weighed 13 per cent (51 kg) more and were 3.6 per cent (5.2 cm) taller than those fed limited amounts. Total, fore and hind body mass increased quadratically irrespective of dietary treatment. Fore body mass comprised 57 per cent of total body mass for both groups and this did not change with age or dietary treatment. Heart girth was directly related (R2 = 0.96) to total body mass. Average daily gains in total body mass of ad libitum fed horses were 13 and 71 per cent more rapid (P less than 0.05) than for limit fed horses in Periods 1 and 3, respectively. Ad libitum fed horses gained hind body mass 25 per cent more rapidly (P less than 0.05) than limit fed horses only in Period 1. Growth curves of wither and croup heights were quadratic in form. Ad libitum fed horses gained 12 and 13 per cent more rapidly at the wither than limit fed horses in Period 1 and overall, respectively. Ad libitum fed horses grew 33 per cent more rapidly at the croup than limit fed horses but only in Period 2. From six to 12 months of age, the wither and croup grew two-fold and four-fold more rapidly than between 12 to 18 months and between 18 to 24 months of age, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of the phase velocity and spatial overlap of spherical resonances on sum-frequency generation in droplets.

The spectrum of the third-order sum-frequency generation (TSFG) that results from the electric fields of the laser E(omega(L)) and of the first-order Stokes stimulated Raman scattering E(omega(1s)) is dependent on the droplet radius. In addition to the amplitude and spatial overlap of the three generating E(omega)'s and of the generating and resultant waves, phase matching between the generating and TSFG waves is an important parameter. We discuss the range of phase velocities of the generating and TSFG waves, which must be tuned to coincide with spherical resonances in order to be guided waves circumnavigating the droplet rim.

Transfer of deep circumflex iliac flaps to the tarsus by microvascular anastomosis in the horse.

Eighteen deep circumflex iliac flaps were elevated in healthy adult horses. Four flaps survived well when elevated as islands, but five orthotopic flaps and nine heterotopic flaps transferred to the tarsus and face failed. Technical reasons could explain the failure of the orthotopic flaps, but not the heterotopic flaps. Failure of the heterotopic flaps was apparently caused by the no-reflow phenomenon.

The effect of exercise on the healing of articular cartilage defects in the equine carpus.

Arthroscopic surgery was performed on 12 horses (2-4 years of age) to create a 7 x 14 mm full-thickness cartilage defect in one radial carpal bone and in the contralateral third carpal bone. Six horses remained confined to a small paddock and six horses underwent a program of increasing exercise consisting of walking, trotting, and cantering for 13 weeks. All lesions showed evidence of healing at week 6 that progressed to more complete healing at week 13. There was no difference in the amount of repair tissue covering the defect. Histologically, the lesions healed with a combination of fibrous tissue and fibrocartilage. The repair tissue was significantly thicker in the exercised horses but there was no difference in repair quality. It was concluded that radial carpal and third carpal lesions have an equal ability to heal and that early postoperative exercise is not detrimental to the repair tissue within these carpal cartilage defects.

Energy uptake and utilization by limit- and ad libitum-fed growing horses.

Eighteen weanling horses were assigned to two treatments: limited or ad libitum feed intake. Growth and feed utilization were evaluated over a 78-wk period. Ad libitum-fed horses gained 24% more (P less than .05) weight than limit-fed horses. Total BW was distributed into 57% fore and 43% hind weight and did not differ between groups regardless of dietary treatment or age. Net gain and ADG in wither height of ad libitum-fed horses exceeded (P less than .05) that of limit-fed horses over 78 wk. Ad libitum-fed horses consumed 19, 44 and 34% more digestible energy (DE) than indicated in 1978 NRC tables from 6 to 12 mo, 12 to 18 mo and 18 to 24 mo of age, respectively. Total DE intakes were positively correlated to weight and therefore were confounded by age. Weight-scaled DE intake of ad libitum-fed weanling horses increased .2% for each 1 C degree decrease in barn temperature below 0 degree C. Maintenance energy requirements were estimated at 37.8 and 35.6 kcal DE/kg BW for limit- and ad libitum-fed horses, respectively. Grams of gain per megacalorie of DE consumed above maintenance ranged from 83 to 24 g/Mcal and were only 22 to 75% of values derived from 1978 NRC tables. Energy guidelines given by NRC were considered suitable for growth based on normalcy of musculoskeletal growth. However, the ADG by our horses, which were fed high-forage diets, were lower than those predicted by 1978 NRC.

Nutrient utilization by limit- and ad libitum-fed growing horses.

Eighteen Quarter Horse and Paint weanling colts were assigned to two treatments, either limit or ad libitum feeding. Nutrient digestibilities of diets were evaluated between 6 and 12 mo, 12 and 18 mo and 18 and 24 mo of age. From 6 to 12 mo, energy digestibility (64 to 68%) was unaffected by feed intake level. Ad libitum-fed horses had energy digestibilities 9 to 10% greater (P less than .05) than limit-fed horses between 12 and 24 mo of age, but adjustment for DM intake removed these differences. Limit-fed, mature ponies used dietary energy similarly to growing horses from 6 to 18 mo of age, but they used digested dietary energy more efficiently (P less than .05) than young horses at 24 mo of age. Ad libitum-fed horses digested more (P less than .05) dietary protein than limit-fed horses between 12 and 24 mo of age, but adjustment for DM intake removed these differences. True digestibilities of dietary Ca were estimated at 71 to 42% among periods, whereas true digestibilities of dietary P ranged from 52 to 6%. Sufficient P was absorbed by all horses between 6 and 18 of age, but by 24 mo of age horses were in negative P balance despite an apparently adequate P intake. Using regression analyses, daily endogenous fecal Ca and P were predicted to be 36 and 18 mg/kg body weight, respectively.

The developmental anatomy of the equine navicular bursa and associated structures.

The navicular bone, navicular bursa and their associated structures were collected from 20 horses ranging in age from 80 days gestation to 2 years post-gestation. The right front foot of every horse was sampled for light microscopy. The development of the navicular bursa and associated structures were studied. Study of the developmental anatomy of the equine navicular bursa established that the bursa is a distinct entity in both the fetus and the adult horse. Development of the bursal cavity in the fetus was found to be complete by 120 days of gestation. Synovial membrane of the navicular bursa was first evident at 100 days of fetal age. With increasing fetal maturation there was a concurrent development in the synovial membrane consisting of increased cellularity, vascularity and villi formation. Nerve fibers or nerve endings were not observed within the synovial membrane of the navicular bursa. However, nerve bundles were often observed within the associated connective tissue, bursal capsule and distal navicular ligament. Pacinian corpuscles were observed in the 200-day fetus in close proximity to the navicular bursa. The development of a fibrous bursal capsule was first evident at 160 days fetal age, thereafter increasing in both thickness and density. Ligaments of the navicular bone were found to develop early in fetal life. At 100 days the collateral sesamoidean ligaments were well developed; however earliest evidence of formation of the distal navicular ligament was at 120 days. In both the fetus and the adult the proximal blood supply to the navicular bone was found to course dorsally in close proximity to the collateral sesamoidean ligament to enter the proximal border of the navicular bone. Concurrent with weight bearing there was a dorsal palmar orientation of the bone trabeculae of the navicular bone. In the young postgestational horses a progressive roughening or fraying of the palmar surface of the navicular bone and the apposing surface of the deep digital flexor tendon was evident.