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Biomedical subjects

K K White

Publications and source records attributed to K K White.

At least 19 recordsLinked to original sources
PubMed2000

In vitro comparison of transfixation and standard full-limb casts for prevention of displacement of a mid-diaphyseal third metacarpal osteotomy site in horses.

OBJECTIVE: To compare transfixation and standard full-limb casts for prevention of in vitro displacement of a mid-diaphyseal third metacarpal osteotomy site in horses. SAMPLE POPULATION: 6 forelimbs from 6 horses euthanatized for reasons not related to the musculoskeletal system. PROCEDURE: A 30 degrees osteotomy was performed in the mid-diaphysis of the third metacarpal bone. Two 4.5-mm cortical bone screws were placed across the osteotomy site to maintain alignment during casting. Two 6.35-mm Steinmann pins were placed from a lateral-to-medial direction in the distal aspect of the radius. A full-limb cast that incorporated the pins was applied. An extensometer was positioned in the osteotomy site through a window placed in the dorsal aspect of the cast, and after removal of the screws, displacement was recorded while the limb was axially loaded to 5,340 N (1,200 lb). Pins were removed, and the standard full-limb cast was tested in a similar fashion. RESULTS: The transfixation cast significantly reduced displacement across the osteotomy site at 445 N (100 lb), 1,112 N (250 lb), 2,224 N (500 lb), and 4,448 N (1,000 lb), compared with the standard cast. CONCLUSION AND CLINICAL RELEVANCE: A full-limb transfixation cast provides significantly greater resistance than a standard full-limb cast against axial collapse of a mid-diaphyseal third metacarpal osteotomy site when the bone is placed under axial compression. Placement of full-limb transfixation casts should be considered for the management of unstable fractures of the third metacarpal bone in horses.

Animals↗
PubMed1998

Influence of form and quantity of selenium on the development and survival of an insect herbivore.

Even plants classified as 'nonaccumulators' can sequester concentrations of sodium selenate, sodium selenite, selenocystine and selenomethionine that can strongly influence insect development and survival. These forms of selenium (Se), tested in diet-incorporation bioassays, proved toxic to larvae of a generalist insect herbivore at relatively low levels. Sodium selenite was the most toxic form tested against Spodoptera exigua (Hübner), with an LC(50) of 9.14 microg g(-1) wet wt (21.11 microg g(-1) dry wt). Selenocystine was intermediate with an LC(50) of 15.2 microg g(-1) wet wt. The least toxic forms, sodium selenate and selenomethionine, had LC(50)s below 50 microg g(-1) dry wt, the upper level for tissues of plants classified as nonaccumulators. Ingestion of some forms of Se also affected growth and development. Increasing concentrations of sodium selenate and sodium selenite decreased pupal weight and added significantly to the time needed for development to the pupal and adult stages. The time required to complete the larval stage increased by over 25% and the time from egg to adult emergence was extended by 22% to nearly 30%. Selenocystine and selenomethionine did not significantly increase developmental times, even at concentrations that killed 90% or more of the test populations. Analyses of relative growth rate, relative growth index, and an analysis of covariance technique for measuring growth indicated that the form of Se affected growth rates, growth inhibition responses of the larvae, and toxicological effects. Thus, quantity and the form of Se accumulating in plants grown on Se-contaminated sites are likely to influence the population dynamics of insect herbivores. The implications of these results for the ecology of contaminated sites are discussed.

Journal Article↗
PubMed1998

Effect of different full-limb casts on in vitro bone strain in the distal portion of the equine forelimb.

OBJECTIVE: To determine the ability of a full-limb transfixation pin cast to protect the distal portion of the equine forelimb from weight-bearing forces by measuring bone strain in vitro on cadaver limbs loaded in a mechanical testing machine. SAMPLE POPULATION: 6 forelimbs from 6 horses. PROCEDURE: Each limb was instrumented with 3 unidirectional metal foil electrical resistant strain gauges. Gauges were placed on the dorsal aspect of the distal portion of the radius and the mid-dorsal portion of the cortex of the third metacarpal bone and the first phalanx. Each limb was tested 3 times, once supported with a transfixation pin cast, once supported by a standard full-limb cast, and finally, uncast. The limbs were tested in a mechanical testing machine under axial loads ranging from 100 to 1,000 lb, and bone strains were recorded at each load. RESULTS: Compared with values for the uncast limb, the transfixation pin cast and the standard full-limb cast significantly (P < 0.001) reduced bone strain on the distal portion of the radius, third metacarpal bone, and first phalanx. Compared with the standard full-limb cast, the transfixation pin cast significantly (P < 0.001) reduced bone strain on the first phalanx. CONCLUSION AND CLINICAL RELEVANCE: Compared with the standard full limb cast, the full-limb transfixation pin cast is more protective of the first phalanx.

Animals↗
PubMed1998

Effect of pin hole size and number on in vitro bone strength in the equine radius loaded in torsion.

OBJECTIVE: To determine the effect of pin hole size and number on the breaking strength of the adult equine radius when loaded in torsion to failure. SAMPLE POPULATION: 54 pairs of equine radii from adult horses. PROCEDURE: For test one, 12 pairs of radii were used to determine the effect of pin hole size on torsional breaking strength. A 6.35-mm hole was drilled in 1 radius, and a 9.5-mm hole was drilled in the contralateral radius. For test two, 36 pairs of radii were randomly assigned to 1 of 3 treatment groups (n = 12) to determine the effect of pin hole number on the torsional breaking strength of the equine radius. One radius of each pair served as a control, and one, three, or six 6.35-mm transcortical holes were drilled in the contralateral radius. For test three, 6 pairs of radii had torsional forces applied directly to the transfixation pins, as opposed to the bone itself. One radius of a pair served as a control, and three 6.35-mm smooth Steinman pins were placed in the contralateral radius. All radii were loaded in torsion to failure, and the breaking strengths were recorded. RESULTS: Compared with the 6.35-mm hole, the 9.5-mm hole significantly decreased torsional strength of the radius. There was no significant difference in mean torsional strength between the control radii and the radii with 1, 3, or 6 transcortical holes or when the transfixation pins were loaded. CONCLUSION: Use of up to three 6.35-mm transfixation pins can be used in a full-limb transfixation pin cast to optimize stiffness without a significant decrease (12%) in bone strength.

Animals↗
PubMed1998

Effect of three types of half-limb casts on in vitro bone strain recorded from the third metacarpal bone and proximal phalanx in equine cadaver limbs.

OBJECTIVE: To determine effect of 3 half-limb casts on bone strains recorded from the proximal phalanx (P-1) and third metacarpal bone (MCIII) of equine cadaver limbs, using a mechanical testing machine. ANIMALS: 12 equine cadaver limbs and 4 live horses. PROCEDURE: Bone strains were recorded at middorsal P-1 and the dorsal cortical aspect of the distal third of MCIII while limbs were variably loaded with 100 to 1,000 lb of force. To determine ability of the cast to protect the distal portion of the limb from weight-bearing loads, strains were recorded with the limb in 1 of the 3 casts and with it unsupported. To determine cast-induced discomfort, weight-supporting and transfixation pin casts were evaluated on 2 live horses RESULTS: All 3 casts significantly reduced bone strain at P-1. Significant differences were observed: mean 61% reduction for the standard half-limb cast, 84% for the transfixation pin cast, and 97% for the weight-supporting cast at weight-bearing force of 500 lb. Only the weight-supporting cast significantly reduced strains recorded from MCIII. The weight-supporting cast was not well tolerated by 2 live horses. CONCLUSIONS: The 3 casts significantly reduced transfer of weight-bearing forces to the distal portion of the limb. The weight-supporting cast effectively reduced strain on the P-1 to near 0, but was well tolerated by live horses. The transfixation pin cast reduced strain on the P-1 by > 80% at weight-bearing loads of 500 lb, and live horses were comfortable. Standard half-limb casts significantly reduced strains on the P-1, but to a lesser degree than did other casts.

Animals↗
PubMed1992

Lyme borreliosis in cattle and horses: a review of the literature.

A complete search of the literature concerning Lyme borreliosis as it relates to horses and cattle was done. The epidemiology, pathogenesis, immunological response to the disease, diagnosis and treatment are discussed. A review of clinical cases in horses and cattle is presented. Clinical signs of Lyme borreliosis in horses include: chronic weight loss, sporadic lameness, laminitis, low grade fever, swollen joints, muscle tenderness, and anterior uveitis. In addition to those clinical signs, neurological signs such as depression, behavioral changes, dysphagia, head tilt and encephalitis can be seen in chronic cases. Borreliosis occurs in cattle, usually as a herd problem. In acute Lyme borreliosis, cattle often will show a fever, stiffness, swollen joints, and decreased milk production. Chronic weight loss, laminitis and abortion are also possible outcomes of borreliosis in cattle. Diagnosis of clinical Lyme borreliosis is difficult and depends upon recognition of clinical signs, a history of possible exposure, and identification of the spirochete in the affected animal. Since the spirochete is very difficult to culture, confirmation of B. burgdorferi infection often relies on serologic testing. Subclinical seropositive animals do occur, thus confusing the diagnosis. An approach to treatment of cattle and horses with Lyme borreliosis is outlined.

Animals↗
PubMed1991

The effects of age on atrophy and recovery in denervated fiber types of the rat nasolabialis muscle.

This study investigates the effects of advancing age on responses of nasolabialis muscle fibers to denervation and reinnervation. The nasolabialis is innervated by the facial nerve and is responsible for the whisking movement of the animal's large vibrissae. In young adult (3-month) and middle-aged (15-month) rats the muscle on one side of the head was denervated by crushing the facial nerve. At specific days postcrush, animals were sacrificed and thick sections of muscle were incubated to demonstrate cytochrome oxidase activity, a mitochondrial enzyme, which differentiated between red, white, and intermediate fiber types. The rate and extent of atrophy and recovery were evaluated using light microscope morphometric methods for which transverse fiber areas were measured and compared to fibers on the contralateral control side. There was an age-related delay in the time of functional return since older animals resumed normal whisking behavior 6 days later than the younger animals. In both age groups, white and intermediate fibers atrophied to the greatest extent and red fibers showed least atrophy. Despite the different responses of the fiber types to denervation, there was no age difference in the maximum degree of fiber atrophy within each fiber type. Age differences did occur in the rate of the denervation response since the middle-aged fibers consistently showed a more rapid significant atrophy than the young adult fibers. During recovery, older fibers may be limited in their ability to attain the size of fibers on the control side. The results indicate that through middle age, the process of advancing age increases the susceptibility of the nasolabialis muscle to denervation but does not alter the maximum extent of atrophy. The ability to recovery to normal fiber size, at least 2 months after denervation, is also age-related.

Aging↗
PubMed1991

Age effects on cytochrome oxidase activities during denervation and recovery of three muscle fiber types.

The rat nasolabialis muscle is comprised of a mosaic of red, white, and intermediate muscle fiber types. Using computerized microdensitometry, cytochrome oxidase (COX) activity was quantitatively analyzed in each fiber type throughout the period of denervation and recovery in young adult (3-month) and middle-aged (15-month) male Sprague-Dawley rats. In animals of both age groups, the nasolabialis muscle on one side of the head was denervated by crushing the facial nerve. At specific days post crush (dpc) ranging from 2 days-2 months, animals were sacrificed and thick sections of normal and denervated muscles were incubated to demonstrate the activity of COX, a mitochondrial enzyme, which differentiates between the three fiber types. Enzyme activities in individual fibers were microdensitometrically analyzed using a digitizing image analyzer. Although a denervation-induced decreased followed by eventual recovery occurred in all fibers of each type, age-related differences were evident. For all types, younger fibers consistently showed decreased COX activity sooner than their older counterparts, and older fibers of all types consistently showed a greater decreased COX activity than the younger fibers. Denervation-induced de-differentiation of muscle fibers led to a more homogeneous population of fiber types in both age groups. Following recovery of function, the magnitude of the fiber enzyme activity change differed according to fiber type and to age, and was consistently smaller in older animals. The normal mosaic pattern of fiber type distribution and normal COX levels were restored 2 months after nerve lesion in both age groups.

Aging↗
PubMed1989

Changes in equine carpal joint synovial fluid in response to the injection of two local anesthetic agents.

The effects of repeated arthrocentesis and injection of local anesthetic agents, lidocaine HCl or mepivacaine HCl on the equine middle carpal joint were investigated. Synovial fluid samples were evaluated before, and 12, 24 and 48 hours following, treatment. The greatest changes from pretreatment values occurred in synovial fluid cellularity. Repeated arthrocentesis caused a moderate increase in cell counts, while injection of local anesthetics caused a greater increase. Alterations in mucin clot quality, hyaluronic acid content, fluid viscosity, total protein and immunoglobulin G were generally of no significance. The most sensitive sampling time to detect changes caused by a given treatment was 24 hours following treatment while the 12 hour sampling period appeared to be the best at detecting differences between treatments. Repeated arthrocentesis has a definite effect on synovial fluid composition but the effects appear to decrease with repeated centesis. Lidocaine HCl and mepivacaine HCl are irritating to the synovial environment. Clear differences between responses to the drugs could not be identified.

Animals↗
PubMed1986

Quality control in the blood bank.

In discussing quality assurance in the blood bank, where many of the standard statistical techniques of measuring accuracy simply do not apply, three questions come to mind: How much? How often? Who says? Because of severe changes in the prospective payment plan and a new interest in cost effectiveness, many transfusion services are re-examining blood banking methodologies and their relative usefulness in promoting patient well-being. Many serologists are beginning to say that "less is better." This concern for simplification and reduction of workload is reflected in the quality control.

Blood Banks↗
PubMed1983

Diaphyseal angular deformities in three foals.

Angular limb deformities in 3 foals were found to originate in the diaphyseal region of the 3rd metacarpal (2) and metatarsal (1) bones. In each case, treatment consisted of wedge ostectomy followed by compression plating. Two foals survived for useful performance; the 3rd was euthanatized because of ischemia of the operated limb. The condition appeared to resemble a similar syndrome in man involving tibial curvature.

Animals↗
PubMed1982

Six cases of squamous cell carcinoma of the stomach of the horse.

Six cases of squamous cell carcinoma of the stomach in horses seen at the New York State College of Veterinary Medicine are compared with 15 similar cases reported previously. Clinical signs included anorexia in all cases, emaciation, fever, anaemia and/or palpable abdominal masses in 3, colic in 2 and dysphagia in one case. Haematological studies revealed normochromic, normocytic anaemia in 3 and absolute neutrophilia in 5 cases. Peritoneal fluid analysis was performed in 4 cases and revealed slightly to moderately elevated total protein concentrations in 3 and a markedly elevated number of white blood cells in 2 cases. Exploratory laparotomy, performed in 3 cases, was essential for a definitive diagnosis. The data presented here suggest that squamous cell carcinoma of the equine stomach may be increasing in frequency and demonstrate the need for prospective epidemiological studies.

Animals↗
PubMed1982

Contact studies of the canine femoropatellar joint.

During development of a closed impact-trauma model, using the canine femoropatellar articulation, animal weight or other readily measured physical characters were correlated with surface area, location, and shape of femoropatellar contact at various femorotibial angulations. The information allows making reasonable predictions regarding femoropatellar contact just before delivery of calibrated closed impact-trauma to the patella. Femoropatellar contact area location, shape, and size were determined in the left pelvic limbs of 10 dogs, ranging in weight from 20.0 to 40.9 kg (mean 27.2 kg). Determinations were made at 90, 110, and 130 degrees femorotibial angulations, using a new casting technique and at 70, 90, 110, 130, and 150 degrees, using a previously described dye technique. Location and shape of the contact areas were relatively constant for a given femorotibial angulation. Bipartite areas of contact were seen on 3 specimens. Using data from the dye technique, a definitive correlation was established between antemortem animal weight and contact area size. Patellar dimensions also correlated well with contact surface area. An inverse relationship between contact area per unit body weight and total body weight was observed. Contact area size did not vary significantly with increasing compressive force resulting from changes in femorotibial angulation. These determinations allow making reasonable predictions of both location and size of articular contact area immediately preceding delivery of closed impact to the joint.

Animals↗
PubMed1981

Corticosteroid and hyaluronic acid treatments in equine degenerative joint disease. A review.

Degenerative arthrosis is perhaps the most common debilitating disease of performance horses. Treatment should be based upon a knowledge of the anatomy and physiology of normal joints and upon an understanding of the processes of degeneration and repair. These topics are briefly reviewed. Although rest is probably, the most beneficial therapy, physical and pharmaceutical treatments are often employed in an effort to speed recovery. The effects and relative benefits of intrasynovial injections of corticosteroids, hyaluronica cid, and Arteparon are considered in detail. Although local corticosteroid therapy is inexpensive and is effective in reducing lameness caused by degenerative joint disease, it is rarely indicated. Septic arthritis and "steroid arthropathy" are two serious sequelae. Whereas the incidence of the former may be avoided through careful technique, the latter effect is inherent in the action of the drug. The accelerated rate of joint destruction observed in steroid arthropathy is due to suppression of chondrocyte metabolism and thus the processes of cartilage maintenance and repair. Hyaluronic acid is present in the synovial fluid and within the matrix of cartilage. The commercial preparation is no approved for use in the United States, but it is commonly obtained from other countries. Although hyaluronate apparently does not function in the lubrication of cartilage surfaces, it may improve lubrication of soft tissues thus decreasing resistance to joint movement and lessening pain. Reports substantiate the effectiveness of hyaluronic acid in treating early cases of degenerative arthrosis despite the fact that the drug does not significantly promote cartilage healing. Arteparon, a polysulfated glycosaminoglycan, has been used in Europe for two decades in the treatment of degeneration joint disease and is currently being tested in this country. The drug is deposited within diseased cartilage and improves the functional properties of the cartilage as well as stimulates cartilage metabolism.

Adrenal Cortex Hormones↗
PubMed1981

Cardiopulmonary resuscitation in the horse.

Depression of the cardiopulmonary system of the horse during anesthesia is not an uncommon event. In many situations simple approaches for improving the function of the horse are necessary to avoid loss of life. This study has been completed utilizing an anesthetic approach frequently used in horses and a cardioresuscitative technique which can be utilized by the practicing veterinarian. Severe depression to arrest were produced experimentally and each animal was resuscitated through support of ventilation and circulation.

Anesthetics↗