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Biomedical subjects

J F Cummings

Publications and source records attributed to J F Cummings.

At least 37 records · Page 2Linked to original sources
PubMed1996

Effect of tibial attachment location on the healing of the anterior cruciate ligament freeze model.

We studied the healing response of a devitalized anterior cruciate ligament to a treatment of initial anterior-posterior joint translation in goats. Devitalization and devascularization were achieved by five successive freeze-thaw cycles. Anterior-posterior translation was surgically altered by an osteotomy of the tibial attachment of the devitalized ligament and its reattachment either in the anatomical position or in a position 5 mm posterior. Six weeks after the first surgery, the same procedure was performed on the contralateral limb, except that the ligament was reattached in the alternate position. Six months after the initial surgery, femur-anterior cruciate ligament-tibia specimens were tested to determine their structural and mechanical material properties. Anatomic ligament placement resulted in reduced anterior-posterior translation (p < 0.05) and greater anterior joint stiffness (p < 0.05). Maximum load (p < 0.05) and ligament stiffness (p < 0.01) also were greater for the anatomically placed anterior cruciate ligaments. The maximum load for anatomically placed ligaments averaged 1.625 +/- 211 N (SEM). The strength of the posteriorly placed anterior cruciate ligament, 895 +/- 164 N was similar to results of historical anterior cruciate autograft reconstructions. Ligament failure occurred near the tibial insertion in the posteriorly placed ligaments more often than in the anatomically placed ligaments (four of five times compared with one of five times). Ligament failure near the tibial insertion occurred with lower mean maximum load than failure at the midsubstance or by bone avulsion (796 compared with 1.592 N: p < 0.05). These data support the hypothesis that ligament laxity is important to the healing and remodeling of anterior cruciate ligament grafts.

Animals↗
PubMed1996

The use of an implantable force transducer to measure patellar tendon forces in goats.

Patellar tendon (PT) force was measured during activity with an implantable force transducer (IFT) in adult goats. PT force, vertical ground reaction force (VGRF) and the animal's speed were recorded for standing, walking and trotting. Following data collection, animals were euthanized and the IFT calibrated in vitro. Standing PT force averaged 207 N. Maximum PT force was approximately 800 N for walking and 1000 N for trotting and occurred at mid-stance. PT force dropped from 200 N at toe-off to 0 N by mid-swing. For each activity, the PT force increased with increases in VGRF. Maximum in vivo PT stress occurred during trotting and measured 29 MPa. This study demonstrates the IFT's usefulness in measuring tendon force directly.

Animals↗
PubMed1996

How have patients reacted to the implications of the DCCT?

OBJECTIVES: To assess the reactions of people with insulin-treated diabetes (ITD) to the results of the Diabetes Control and Complications Trial (DCCT). RESEARCH DESIGN AND METHODS: A leaflet documenting the purpose and results of the DCCT was circulated to all 771 patients ages 15-60 years with ITD attending our clinic. Patients were invited to complete and return a questionnaire on their responses. RESULTS: Of 550 respondents, 330 felt encouraged to improve glycemic control. Female respondents (P = 0.003) and younger age-groups (15-25 years, P = 0.001) were most likely to want to improve control. Patients with long duration of diabetes (> 20 years, P = 0.00001), hypoglycemia unawareness (P = 0.0001), or previous severe hypoglycemia (P = 0.001) were less likely to want to improve their control. Fear of hypoglycemia concerned all age-groups, whereas female respondents were most likely to be worried about the potential for weight gain (P = 0.00006). CONCLUSIONS: Knowledge of the results of the DCCT encourages significant numbers of patients to want to improve glycemic control. Fear of hypoglycemia and, in women, weight gain may prove significant impediments to the clinical implementation of the results of the DCCT.

Adolescent↗
PubMed1995

Endothelial lipopigment as an indicator of alpha-tocopherol deficiency in two equine neurodegenerative diseases.

Two spontaneous neurodegenerative diseases of the horse, equine motor neuron disease (EMND) and equine degenerative myeloencephalopathy (EDM), have been associated with alpha-tocopherol deficiency, and both were characterized by prominent accumulations of endothelial lipopigment in the small vessels of the spinal cord. These endothelial pigment deposits appear to be reversible. In EMND horses pasture-supplemented for 9 months or more after the progression of weakness and wasting had arrested, there was very little endothelial lipopigment. The origin and the potential effects of these endothelial lipopigment accumulations are discussed.

Animals↗
PubMed1995

Factors affecting sensitivity of a transducer for measuring anterior cruciate ligament force.

In order to determine the measurements and calibration methods necessary to accurately measure in vivo forces in the anterior cruciate ligament (ACL) of the goat, an in vitro study was conducted to evaluate the effect of several factors that could influence the sensitivity of a transducer implanted within the ligament. Four factors were studied in six specimens: flexion angle [0 degrees, 10 degrees, 30 degrees, 50 degrees, and 70 degrees from full extension (FFE)]; tibial rotation (0 degrees and 10 degrees of internal rotation at 30 degrees, 50 degrees, and 70 degrees flexion FFE); loading rate (cycling frequencies of 0.2, 0.5, 1.0, and 2.0 Hz); and temperature (22 degrees C and 37 degrees C). Anteroposterior tibial displacements were applied to the specimens following tissue resection to isolate the ACL. The resultant ACL force magnitude was measured with a multi-component load cell, and transducer sensitivity was calculated as the slope of the output vs force curve in the linear response region. Transducer sensitivity varied with joint position in each specimen, but there was no consistent trend from specimen to specimen in how the sensitivity changed. As a result, there were no statistically significant mean differences (p > 0.05). There were no significant differences and little variation in sensitivity due to changes in either loading rate or tissue temperature, although the latter produced a voltage offset. The results show that the transducer output with zero force on the ligament must be determined in vivo, after which in vitro calibrations may be conducted at room temperature.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Incidence and risk factors of equine motor neuron disease: an ambidirectional study.

We have conducted an ambidirectional study to estimate the incidence of equine motor neuron disease (EMND) in the northeastern US. The clinical and pathological features of EMND are similar to those described in human motor neuron disease. We have also collected data on all EMND cases reported in the US and described the geographic distribution of the disease. To identify factors associated with the risk of EMND, the authors assembled 163 control horses from the population in which cases were identified. The significance of association between the hypothesized factors and the risk of EMND was evaluated using the logistic regression analysis and the risk was estimated using the odds ratio. Seventy-eight horses in North America were diagnosed with EMND between the period of January 1985 and November 1993. Most of the cases were identified in the Northeast of the US and the incidence of EMND appears to be increasing in this area. Factors found to be significantly associated with EMND were breed and the age of the horse. Quarter horses were the only breed with a significantly higher risk of EMND (odds ratio = 2.3). The risk of EMND increased with age, reached a peak around 16 years of age and then declined. The sex of the horse was not associated with the risk of the disease.

Age Distribution↗
PubMed1995

Epidemiologic evidence for clustering of equine motor neuron disease in the United States.

OBJECTIVE: To examine the regional variations in the distribution of equine motor neuron disease (EMND) in the United States and the factors that might explain those variations. DESIGN: Cluster investigation and case-control study. SAMPLE POPULATION: The study population consisted of 97 horses with histopathologically confirmed EMND and 698 controls with diagnosis of other spinal cord disorders at 21 US veterinary teaching hospitals participating in the Veterinary Medical Data Base. PROCEDURE: The total horse population of the United States was divided into 21 regions, and the regional incidence rates of EMND from January 1985 through January 1995 were estimated. Moran's index of spatial autocorrelation was calculated to test for spatial clustering of the disease. The 21 regions were then joined in broader areas according to the similarity of their EMND rates by means of the cluster analysis statistical technique. Finally, the role of potential confounding factors (age at diagnosis, month of diagnosis, breed, and sex) in the present distribution of EMND was assessed, using logistic regression analysis. RESULTS: Differences in estimated rates across the 21 regions resulted in a strong pattern of spatial clustering of EMND in the United States. The geographic units were grouped into 5 risk regions, with the gradient of EMND incidence rates increasing from the western states (almost 0 cases/1,000,000 horse-years) toward New England (20.78 cases/1,000,000 horse-years). Reported risk factors of EMND (age, breed) and other extraneous factors (sex, month of diagnosis) could not explain the observed geographic variations of disease rates. Nevertheless, there is evidence of some confounding attributable to age and breed. CONCLUSIONS: Although the mechanism responsible for the clustering of EMND in northeastern states is still unexplained, it is not an epiphenomenon caused by regional differences in the distribution of the factors investigated.

Animals↗
PubMed1994

In vivo forces in the anterior cruciate ligament: direct measurements during walking and trotting in a quadruped.

In vivo forces in the anterior cruciate ligament (ACL) were measured in three adult goats during quiet standing and during gait (walking or trotting). A modified pressure transducer (MPT) was implanted within the anteromedial band of the ligament to make direct measurements of ACL force. One or two days following implantation, measurements were made of ACL force, knee joint flexion angle, ground reaction forces, and speed of locomotion. MPT calibration was performed in vitro using anteroposterior displacement tests at six flexion angles. The ACL was loaded during quiet standing (30-61 N) and during the stance phase of gait. Peak ACL forces were achieved within the first 40% of stance, with magnitudes ranging from 63 to 124 N during walking and from 102 to 150 N during trotting. The average ACL force during the stance phase ranged from 34 to 68 N while walking and from 46 to 69 N while trotting. The partial correlations between peak ACL force and speed, and between average ACL force and speed, were both statistically different from zero (p < 0.01). ACL forces dropped to zero during the swing phase in all trials. ACL forces were less than 15 N throughout swing in two of the animals, both of which did not extend their knees during gait beyond 20 degrees from full extension. In the animal which did show knee extension beyond 40 degrees (20 degrees from full extension), ACL loading occurred during late swing. The magnitude of the peak ACL force during late swing was significantly correlated with the extent of knee extension in this animal.

Animals↗
PubMed1994

Equine motor neuron disease: findings in 28 horses and proposal of a pathophysiological mechanism for the disease.

Over a three and one-half year period, 28 adult horses were diagnosed with equine motor neuron disease (EMND). The most commonly identified environmental risk factors for a horse having EMND were absence of grazing for more than a year and provision of poor quality hay. Quarter Horses were 5.4 times more at risk than other breeds but this was thought to be an epiphenomenon related to the frequency of Quarter Horses at boarding stables. Weight loss, excessive recumbency and/or trembling were the first signs noted. Other clinical diagnostic signs included: constant shifting of the weight in the rear limbs, abnormally low head carriage and muscle fasciculations. Excellent to ravenous appetites were present in all cases and marked coprophagia in some cases. Abnormally high serum concentration of muscle-derived enzymes was the only consistent serum chemistry abnormality found. Abnormal glucose absorption, increased cerebrospinal fluid total protein and intrathecal production of IgG were identified in a number of cases. Euthanasia was performed on 5 horses within 4 days of hospital admission, because of inability to stand or respiratory distress, and on 18 horses after the diagnosis had been completed. Five affected horses were maintained for observational purposes for periods of 9 months to over 2 years after the onset of clinical signs. They were given access to pasture and 2 were given supplemental vitamin E as the only therapy. Marked clinical improvement occurred in the 4 more acutely affected horses. Pathological findings, preference of type 1 muscle fibre atrophy and lipopigment accumulation within the capillary endothelium of the spinal cord of all cases, supported the hypothesis of EMND being an oxidative disease.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1994

Substance P immunohistochemical study of the sensory innervation of normal subchondral bone in the equine metacarpophalangeal joint.

Serial sections of bone and soft tissue from the metacarpophalangeal joints of 2 mature and 2 immature horses were evaluated for substance P immunoreactive sensory nerve fibers. Formalin-fixed specimens were sectioned, either nondemineralized or demineralized with formic acid or EDTA. Rabbit antiserum to substance P (SP) was used in the streptavidin-biotin-peroxidase complex method for immunolocalization of SP antigen, and staining with 3,3'-diaminobenzidine was used for permanent identification of SP fibers. Abundant sensory nerve fibers were identified in the joint capsule, synovial membrane subintimal layers, collateral ligaments, suspensory ligament and distal sesamoidean ligament attachments to the sesamoid bones, and the periarticular periosteal layers. Sparse SP-immunoreactive nerve fibers were found in subchondral bone plates of the metacarpus, proximal first phalanx, and dorsal articular surface of the sesamoid bones. Most SP fibers were associated with blood vessels in the small cancellous spaces and haversian canals of the subchondral bone. The deeper marrow spaces contained increased numbers of SP sensory fibers; a few appeared in small groups and as several SP-immunoreactive fibers in a larger nerve. Cortical bone contained only a few SP fibers in the haversian canals. Substance P fibers were not identified in the osteocytic lacunae, canaliculi, or the bony lamellae of the haversian systems of the subchondral bone plate, and its extension to the metaphyseal and diaphyseal cortical bone. Equine metacarpophalangeal joint soft tissues have an abundant sensory nerve supply, similar to that of other species.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1994

Epidemiology of equine motor neuron disease.

Equine motor neuron disease (EMND) is a newly recognized neurodegenerative disorder of bulbospinal motor neurons in the horse. We conducted a case-control study to identify intrinsic factors associated with the risk of this disorder. Seventy-four cases and 160 controls were assembled. Controls included horses diagnosed with equine protozoal myelitis, equine degenerative myeloencephalopathy, and cervical stenotic myelopathy during the same time period as the cases. Logistic regression analysis was used to evaluate the association of each hypothesized factor while simultaneously controlling for the effect of other factors. Factors found to be significantly associated with the risk of the disease were breed and age of the horse. Quarterhorses are at a higher risk in comparison to other breeds of horse.

Age Factors↗
PubMed1993

Motor neuron degeneration in a horse.

A 9-year-old Quarter Horse mare was examined because of progressive weight loss, weakness, muscle atrophy and tremors, and behavioral change. Selenium and glutathione peroxidase assays, blood lead analysis, erythrocyte transketolase analysis, pseudorabies and Borrelia burgdorferi serology, electromyography, and CSF analysis were performed. Motor neuron degeneration was diagnosed by microscopic examination of neural tissues. The cause of the disease was not substantiated, but several possibilities were excluded via diagnostic testing. Diagnosis of motor neuron degeneration in horses may be made from an accurate history, thorough neurologic examination, and ancillary testing. In particular, antemortem diagnosis may be based on finding scattered angular atrophy of predominantly type-1 or of type-1 and -2 skeletal muscle fibers in frozen sections of muscle biopsy specimens.

Animals↗
PubMed1993

Neuropeptide distributions in the colon, cecum, and jejunum of the horse.

The pelvic flexure portion of the equine large colon is the proposed location of a pacemaker mechanism. This study was conducted to ascertain whether the distribution of certain putative neurotransmitters differs at the pelvic flexure compared to other sampling sites. Tissue samples were collected from the intestinal tracts of six horses. Serial sections from these samples were reacted with primary antisera specific for substance P, vasoactive intestinal polypeptide (VIP), methionine-Enkephalin, and calcitonin gene-related peptide (CGRP). The regional distribution of immunoreactive neuronal elements was uniform for each of the neuropeptides except VIP. Although neurons exhibiting VIP-like immunoreactivity were abundant throughout the colon, they were somewhat more plentiful near the apex of the pelvic flexure and the left dorsal colon. These neurons may participate in the initiation and propagation of the propulsive/retropulsive contraction waves, which emanate from this location and are believed to lend a sphincter-like capacity to the pelvic flexure. The submucosal plexus was replete with neurons with intense substance P and VIP-like reactivity. Reactive fibers left submucosal ganglia to project to the intestinal mucosa, reflecting a possible secretogogic role for these neurons. This role may be especially important for the horse as a hindgut fermenter. There were abundant methionine-Enkephalin and substance P-like reactive varicosities throughout the myenteric plexus, many of which established a pericellular plexus of varicose fibers. The abundance of these varicosities, which may correlate with a high degree of neuronal integration, did not vary regionally. These data may enhance our understanding of both normal colonic peristalsis and motility disorders caused by a depletion of these neuropeptides.

Animals↗
PubMed1993

Eosinophilic cytoplasmic inclusions in sporadic equine motor neuron disease: an electron microscopic study.

Equine motor neuron disease (EMND) is a sporadic, progressive neurodegenerative disorder that has been identified recently in horses of different breeds in North America. The cause is unknown. Pathologic changes which occur in spinal and certain brain stem motor neurons include chromatolysis, swelling, neurofilamentous accumulation, and development of eosinophilic cytoplasmic inclusions. Punctate eosinophilic inclusions, the type usually encountered in degenerating neurons, resembled Bunina bodies at the light microscopic level, but differed in their ultrastructural composition. These and less common but larger juxtanuclear inclusions appeared to be aggregated vesicular residues of membranous organelle degradation. The third kind of eosinophilic inclusion was a marginated derivative of endoplasmic reticulum and consisted of large membrane-bound accumulations of finely granular material. It was concluded that, although the distribution and nature of the lesions in EMND appeared similar to those of human motor neuron disease, none of the equine eosinophilic inclusions duplicated the ultrastructure of Bunina bodies.

Animals↗
PubMed1993

Subclinical lumbar polyradiculopathy, polyneuritis and ganglionitis in aged wild and exotic mammalians.

Subclinical lumbar polyradiculopathy was present in the intradural dorsal and ventral nerve rootlets of 19 aged individuals of the following wild and exotic mammalian species: woodrat, raccoon, mink, lynx, reindeer, red deer, musk ox, scimitar-horned oryx, Arabian oryx, hybrid waterbuck, Persian onager, Przewalski's wild horse, Malayan sun bear, Asian elephant, East African river hippopotamus, vervet monkey and rhesus monkey. It was characterized by mild to severe multifocal ballooning of myelin sheaths. Occasionally, ballooned myelin sheaths contained thin strands of myelin and macrophages surrounding distorted axons. Additionally, a mild incidental lymphocytic polyneuritis was present in intradural nerve rootlets of the Malayan sun bear, and a moderate lymphocytic spinal ganglionitis in the East African river hippopotamus.

Age Factors↗