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Biomedical subjects

R M McLaughlin

Publications and source records attributed to R M McLaughlin.

At least 19 recordsLinked to original sources
PubMed2006

The use of radiofrequency energy during arthroscopic surgery and its effects on intraarticular tissues.

The use of radiofrequency (RF) energy has become very popular in human and veterinary arthroscopic surgery since the late 1990s. Both monopolar and bipolar RF units are available. Application of RF energy to joint capsular tissue leads to immediate tissue shrinkage that is both power and temperature dependent. Changes in joint capsular tissue have been noted at temperatures greater than 65 degrees C. Treatment of articular cartilage with RF energy leads to immediate chondrocyte damage. This damage is also power and temperature dependent and is observed at temperatures as low as 45 degrees C. Caution should be used when applying RF energy within a joint to prevent or minimize articular cartilage injury.

Animals↗
PubMed2006

The role of negative intra-articular pressure in the maintenance of shoulder joint stability in dogs.

The objective of this study was to evaluate the effect of negative intra-articular pressure on shoulder joint stability in canine cadavers. Cadaver forelimbs from 12 mature dogs were used. The forelimbs were placed in a testing frame and axially preloaded with 4 kg of weight. Shoulder joint stability was tested in flexion, extension, and neutral position before and after venting of the joint capsule. Humeral translation relative to the glenoid was induced by applying a 3 kg load in three different directions (cranial, lateral, and medial) and quantitatively measured by use of an electromagnetic motion tracking system. Peak translational data were compared in each joint position before and after venting of the joint capsule. After venting the shoulder joint capsule, a significant increase in translation was observed in the cranial direction with the joint in neutral position and in the medial direction with the joint in extension. The horizontal translations measured after venting of the joint capsule were likely not clinically relevant. Negative intra-articular pressure is not a major contributor to shoulder stability in dogs during weight-bearing.

Animals↗
PubMed2005

Evaluation of healing in feline femoral defects filled with cancellous autograft, cancellous allograft or Bioglass.

Cancellous bone grafting is a widely accepted technique in human and veterinary orthopaedic surgery. However, the use of autogenous bone graft is limited by the additional surgical time required to harvest the graft, the morbidity associated with the donor site, and the limited availability of cancellous bone, especially in feline patients. Various allografts and bone graft substitutes are available commercially but have not been fully evaluated for efficacy in the cat. The purpose of this study was to compare the incorporation of autogenous and allogenous cancellous bone graft and Bioglass, a synthetic bone graft substitute, in femoral defects in cats. Four (4.0 mm diameter) defects were created in the lateral diaphyseal cortex of the left femur with an orthopaedic drill. In each femur, one of the cortical defects was filled with autogenous cancellous graft (harvested from the tibia), one was filled with allogenic cancellous graft, and one was filled with Bioglass. The fourth defect remained unfilled. Graft incorporation within the femoral defects was evaluated by radiographic evaluation every two weeks. Six weeks after the grafting procedure, the cats were euthanatized and high detailed radiography, dual energy X-ray absorptiometry (DEXA), histopathology and histomorphometry of the defects were performed. Satisfactory bone healing was observed within all of the defects.

Animals↗
PubMed2001

Hind limb lameness in the young patient.

Hind limb lameness is seen frequently in young dogs and may result from congenital abnormalities, traumatic injuries, or developmental diseases. An understanding of the patient's history, a good physical and radiographic evaluation, and sound knowledge of the common diseases affecting immature dogs permit early diagnosis and successful treatment in most cases.

Animals↗
PubMed2001

Kinetic and kinematic gait analysis in dogs.

Kinetic and kinematic gait analysis provides objective, quantifiable, and repeatable information on normal and abnormal gait in dogs. Data collection requires specialized equipment, and techniques must be carefully controlled to ensure that accurate measurements are obtained. Force-plate and kinematic analysis is currently used primarily as a research tool to study various gait abnormalities and objectively assess treatment efficacy. As future research identifies characteristic changes associated with specific types of lameness, the use of gait analysis to evaluate individual clinical patients with lameness should become more valuable. Specialized gait analysis techniques may eventually enable veterinarians to accurately diagnose subtle lameness, better evaluate dogs with resolving lameness, and accurately select the appropriate time to return an athletic dog to exercise after recovery from an injury.

Animals↗
PubMed2000

The effect of chronic food and water restriction on open-field behaviour and serum corticosterone levels in rats.

In operant conditioning experiments, two methods are commonly used to motivate laboratory rats to perform designated tasks. The first is restricting food so that rats are forced to lose 20% of body weight within one week, followed by maintenance at 80% of the baseline weight for the remainder of the experiment. The second is restricting access to water to 15 min in each 24 h period. These methods are effective in motivating the animals. There is, however, little information available on the effects on performance in tests of behaviour that are not related to operant conditioning. In addition, it is not clear if these commonly used methods of food and water restriction will lead to physiological stress as indicated by an elevation of serum corticosterone. Male rats were either food-restricted to reduce and maintain their weight at 80% of baseline weight, or were restricted to 15 min access to water every 24 h. Activity in the open field was significantly greater in food-restricted rats than in water-restricted or control rats, but freezing behaviour was similar in all experimental groups. Food-restricted rats had a higher mean serum corticosterone level than water-restricted and control rats 37 days after the start of the experimental period. These data suggested that chronically restricting food and maintenance of body weight at 80% of baseline body weight led to significant behavioural changes and physiological stress. In contrast, water restriction did not lead to changes in behaviour or corticosterone levels. A second experiment was conducted to compare the effects of food restriction to 80% of baseline body weight, as described above, with a less stringent protocol in which test rats were initially reduced to 80% of baseline weight, but were then maintained at 80% of an ad libitum fed control rat's weight. Serum corticosterone levels and adrenal gland weights were measured after the initial week of forced weight loss and after maintenance for 21 days. Forced loss of 20% of body weight in the first week led to significantly increased serum corticosterone levels and adrenal gland weights compared to ad libitum fed controls. Serum corticosterone levels and adrenal gland weights in rats maintained at 80% of their initial body weight for 21 days remained higher than ad libitum fed control rats. However, rats maintained at 80% of an ad libitum fed control rat's weight did not differ from control rats in serum corticosterone levels or adrenal gland weights at the end of the 21-day study period. Adjustment of the feeding regimen in this manner eliminated physiological evidence of chronic stress.

Adrenal Glands↗
PubMed1999

Scintigraphic evaluation of dogs with acute synovitis after treatment with glucosamine hydrochloride and chondroitin sulfate.

OBJECTIVE: To evaluate the effects of orally administered glucosamine hydrochloride (GlAm)-chondroitin sulfate (CS) and GlAm-CS-S-adenosyl-L-methionine (SAMe) on chemically induced synovitis in the radiocarpal joint of dogs. ANIMALS: 32 adult mixed-breed dogs. PROCEDURE: For 21 days, all dogs received a sham capsule (3 groups) or GlAm-CS (prior treatment group) in a double-blinded study. Unilateral carpal synovitis was induced by injecting the right radiocarpal joint with chymopapain and the left radiocarpal joint (control joint) with saline (0.9% NaCl) solution. Joints were injected on alternate days for 3 injections. After induction of synovitis, 2 groups receiving sham treatment were given GlAm-CS or GlAm-CS-SAMe. Another group continued to receive sham capsules (control group). Joint inflammation was quantified, using nuclear scintigraphy, before injection of joints and days 13, 20, 27, 34, 41, and 48 after injection. Lameness evaluations were performed daily. RESULTS: Dogs given GlAm-CS before induction of synovitis had significantly less scintigraphic activity in the soft-tissue phase 48 days after joint injection, significantly less uptake in the bone phase 41 and 48 days after joint injection, and significantly lower lameness scores on days 12 to 19, 23, and 24 after injection, compared with other groups. CONCLUSIONS AND CLINICAL RELEVANCE: Analysis of results of this study suggest that prior treatment with GlAm-CS for 21 days had a protective effect against chemically induced synovitis and associated bone remodeling. Prior treatment with GlAm-CS also reduced lameness in dogs with induced synovitis.

Administration, Oral↗
PubMed1998

Water content and glycosaminoglycan disaccharide concentration of the canine meniscus.

OBJECTIVE: To determine the regional composition of water and glycosaminoglycan (GAG) disaccharides of the canine meniscus. SAMPLE POPULATION: 52 menisci from the stifle of dogs. PROCEDURE: Regional sections of each meniscus were weighed, dried, and reweighed to determine water content. Dried tissue specimens were subjected to enzymatic digestion. Analysis and quantification of disaccharide degradation products were performed, using high-performance liquid chromatography. RESULTS: Water content was approximately 65% in polar and central regions of the canine meniscus. Water content of the central region of the lateral meniscus was significantly higher than that of the medial meniscus (P = 0.0090). Chondroitinase digestion of canine meniscal tissue yielded detectable delta Di-HA, delta Di-4S, and delta Di-6S GAG disaccharides. Disaccharides specific to dermatan sulfate and chondroitin D or E sulfate were not detected. Concentrations of delta Di-4S and delta Di-6S were significantly greater in the lateral central region, compared with the medial central region (P = 0.0005 and 0.0002, respectively). CONCLUSION: Water content and delta Di-4S and delta Di-6S concentrations were significantly lower in the central region of the medial meniscus, compared with the central region of the lateral meniscus. Reduced tissue hydration of the medial central region may have been a direct result of its overall decrease in total GAG content. CLINICAL RELEVANCE: The ability to evaluate subtle differences in tissue GAG composition by analytical measurement of their constituent disaccharides may aid in the understanding of the complex material properties of the normal and diseased meniscus, which may be applied to the study of meniscal healing and biomechanics.

Animals↗
PubMed1997

Fascia lata autograft for treatment of congenital cranial cruciate ligament deficiency in a llama.

An 11.4-kg female llama that had been born without assistance while its dam was under observation at the veterinary teaching hospital was observed to ambulate abnormally on its right hind limb. A cranial drawer sign could be elicited in the right stifle. Cranial displacement of the tibia relative to the femur and dysplasia of the proximal end of the tibia were seen on radiographs. When the cria was 10 days old, the joint was stabilized with a fascia lata autograft. At the time of surgery, a segment of thin, loose tissue was found where the cranial cruciate ligament would have been. Three years after surgery, the llama gave birth to a normal cria and was 60 days pregnant with a second cria. To our knowledge, congenital cranial cruciate ligament deficiency with tibial dysplasia has not been reported in llamas. The heritability of these defects is unknown.

Animals↗
PubMed1996

Effects of subject velocity on ground reaction force measurements and stance times in clinically normal horses at the walk and trot.

OBJECTIVE: The objective of the study reported here was to evaluate the effects of changing velocity on stance time and ground reaction force (GRF) measurements in horses at the walk and trot. DESIGN: Force plate gait analysis was used to evaluate clinically normal horses at variable velocities. Ground reaction force measurements and stance times were recorded and compared. ANIMALS: 12 adult horses. PROCEDURE: Data were obtained from 192 valid trials at the walk and 162 valid trials at the trot. Vertical, braking, and propulsive peak forces and impulses were measured. Pearson's correlation coefficients were determined for velocity and stance time and all measured forces and impulses in the forelimbs and hind limbs. Trials were divided into distinct velocity ranges. Trials obtained at velocities within the established ranges were analyzed to evaluate changes in vertical, braking, and propulsive peak forces and impulses at differing speeds within the walk and trot gaits. RESULTS: At the walk and trot, a significant negative correlation was found between velocity and forelimb and hind limb stance times. Velocity and stance time were significantly correlated with many of the GRF and impulse measurements. Velocity was significantly correlated with vertical and braking forces in the hind limbs at the walk, with vertical force in the forelimbs at the trot, and with braking force in the forelimbs and hind limbs at the trot. Velocity and stance time correlated significantly with forelimb and hind limb vertical impulses. Forelimb and hind limb stance times decreased significantly as velocity increased. Hind limb braking force increased and forelimb and hind limb vertical impulses decreased significantly as walk velocity increased. Forelimb braking force increased significantly between velocity ranges at the trot. CONCLUSIONS: Results of this study confirm that a significant negative linear correlation exists between subject velocity and stance times in clinically normal horses at the walk and trot. Significant correlations were also identified between velocity and many GRF measurements, indicating that subject velocity does influence the generation of GRF measurements in horses. Variation in subject velocity should be minimized when performing force-plate analysis in horses.

Animals↗
PubMed1995

Traumatic joint luxations in small animals.

Proper management of traumatic joint luxations in small animals requires complete assessment and treatment of life-threatening injuries, early joint reduction, stabilization of the joint, and early return to joint function. The methods of reduction vary with the joint involved but can often be achieved in a closed fashion. Joint stability is maintained by external coaptation or internal stabilization methods, depending on the degree of laxity present after reduction. Once joint stability is achieved, passive and active physical therapy is important to establish normal joint function. Reluxation, lameness, and degenerative joint disease are possible sequelae of traumatic joint luxations.

Animals↗
PubMed1995

Retrospective evaluation of production characteristics in Sinclair miniature swine--44 years later.

Three hundred seventy-one litter records collected between 1985 and 1993 from 156 Sinclair S-1 miniature sows, a Hormel-derived strain of miniature swine, were retrospectively analyzed and compared with published records for 1950 to 1952 and 1963 to 1965. The effect of several variables such as season and month of parturition, age of sow, parity, and litter size on reproductive parameters of the Sinclair miniature swine were evaluated. The mean and standard error of the mean for litter size, number of liveborn, number of stillborn, and litter size at weaning of the Sinclair S-1 miniature swine were 7.20 +/- 0.12, 6.57 +/- 0.12, 0.63 +/- 0.06, and 5.75 +/- 0.12 piglets respectively. From a total of 2,436 liveborn piglets, 2,133 (87.56%) were weaned. The litter size at birth was similar to that previously reported for this strain of swine, whereas the litter size at weaning increased (P < 0.001) from 4.7 piglets during 1963 to 1965 to 5.8 piglets in our study. The average birth weight decreased (P < 0.001) from 0.90 kg in 1950 to 1952 and 0.72 kg in 1963 to 1965 to 0.59 kg in our study. Reproductive variables that had a considerable effect on the miniswine reproduction included month of parturition, age of sow, parity, and litter size. Primiparous sows had the smallest litter size and lowest number of weaned piglets. Sows during their second and third parity or sows between 2 and 4 years old had the best reproductive performances. Litter size and number of stillborn increased with parity and age of sow, resulting in fewer piglets weaned in older sows.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1994

Effects of subject stance time and velocity on ground reaction forces in clinically normal greyhounds at the trot.

Force plate gait analysis was used to study the effects of subject stance time and velocity on ground reaction forces in 6 adult Greyhounds at the trot. Data for 210 valid trials were obtained. Stance time negatively correlated with velocity (r = -0.85 for the forelimbs, r = -0.61 for the hind limbs), decreasing as velocity increased. Stance time in the forelimbs and hind limbs correlated more closely with changes in vertical peak force and impulse than did velocity. The trials were divided into 3 distinct velocity ranges (V1 = 1.5 to 1.8 m/s, V2 = 2.1 to 2.4 m/s, and V3 = 2.7 to 3.0 m/s), 3 distinct forelimb stance time ranges (FST1 = 0.144 to 0.176 second, FST2 = 0.185 to 0.217 second, and FST3 = 0.225 to 0.258 second), and 3 distinct hind limb stance time ranges (HST1 = 0.105 to 0.132 second, HST2 = 0.139 to 0.165 second, and HST3 = 0.172 to 0.198 second). Peak forces increased as velocity increased and decreased as stance time increased. Vertical impulse decreased as velocity increased and increased as stance time increased. The relation between stance time, subject velocity, and ground reaction forces was documented for clinically normal Greyhounds at the trot. Changes in stance time accurately reflected changes in subject velocity and ground reaction forces in clinically normal dogs and could be used to normalize trial data within a sampling period.

Animals↗
PubMed1994

Effects of subject stance time and velocity on ground reaction forces in clinically normal greyhounds at the walk.

Force plate gait analysis was used to study the effects of subject stance time and velocity on ground reaction forces in 5 adult Greyhounds at the walk. Data from 146 valid trials were obtained. Stance time and velocity were linearly related, and stance time had a strong, negative correlation with velocity (r = -0.72 for the forelimbs, r = -0.56 for the hind limbs). Stance time correlated more closely with changes in peak vertical force and impulse than did velocity. Stance time and velocity correlated less strongly with braking and propulsion forces and impulses. The trials were divided into 2 distinct velocity ranges (V1 = 0.92 to 1.03 m/s, V2 = 1.06 to 1.17 m/s), 2 distinct forelimb stance time ranges (FST1 = 0.40 to 0.48 second, FST2 = 0.50 to 0.55 second), and 2 distinct hind limb stance time ranges (HST1 = 0.40 to 0.45 second, HST2 = 0.46 to 0.51 second). Five trials from each dog were included in each range, and the mean values were used to evaluate changes in ground reaction forces between groups. Peak vertical force in the forelimbs decreased significantly (P = 0.048) as FST increased; however, difference was not detected in vertical force between velocity groups. Peak vertical force in the hind limbs decreased significantly (P = 0.001) as HST increased and increased significantly (P = 0.000) as velocity increased. Differences were not observed between groups in forelimb or hind limb braking and propulsive forces.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Flow cytometry, morphometry and histopathology as biomarkers of benzo[a]pyrene exposure in brown bullheads (Ameiurus nebulosus).

Brown bullheads were given a single intraperitoneal dose of 0, 5, 25 or 125 mg kg-1 benzo[a]pyrene (BaP), a carcinogenic polycyclic aromatic hydrocarbon, and evaluated over 18 months. Flow cytometric analyses of hepatocyte DNA content indicated an increase in DNA synthesis in BaP-exposed fish prior to day 14 post-exposure. Thereafter, all flow cytometric variables returned to initial levels. Histopathological evaluation of livers from fish sampled at 18 months revealed significant differences among treatments in the amount of hepatic macrophage ceroid pigmentation and basophilic staining intensity. No neoplasms or changes in blood cell DNA content were detected. Significant morphometric variations existed among fish, but differences between sexes overshadowed differences attributable to dose. Flow cytometry yielded no evidence of long-term DNA alterations from a single exposure to BaP; however, the differences detected by DNA analysis shortly after the toxic event suggest that flow cytometric cell cycle analysis may be useful for documenting continuing exposures.

Animals↗
PubMed1992

The effect of neutrophils, tumor necrosis factor, and granulocyte macrophage/colony stimulating factor on Babesia bovis and Babesia bigemina in culture.

Bovine neutrophils, human recombinant tumor necrosis factor-alpha (TNF), and bovine recombinant granulocyte macrophage/colony stimulating factor (GM/CSF) were added to microaerophilic cultures of Babesia bovis and Babesia bigemina to determine if those substances could inhibit growth. Incorporation of [3H]hypoxanthine by the Babesia spp. was utilized as an indirect measure of parasite growth. When neutrophils were added to cultures of B. bovis and B. bigemina, the highest percentage inhibition of growth was attained. There was no significant enhancement of neutrophil killing when TNF or GM/CSF or both were added to either Babesia spp. Addition of TNF or GM/CSF or both substances (without neutrophils) resulted in an increase in growth of B. bovis and B. bigemina. For B. bovis, the group that contained neutrophils only and the group that contained neutrophils and TNF resulted in significantly higher growth inhibitions than the treatment group which contained neutrophils and GM/CSF or the group that contained neutrophils, TNF, and GM/CSF. No significant differences in inhibition were observed for the same treatment groups between B. bovis and B. bigemina.

Animals↗