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Biomedical subjects

M A Kelly

Publications and source records attributed to M A Kelly.

At least 91 records · Page 5Linked to original sources
PubMed1993

The influence of HLA-DR and -DQ alleles on progression to multiple sclerosis following a clinically isolated syndrome.

A 5-year follow-up study was performed on 70 Caucasian patients presenting with isolated neurological syndromes of the optic nerve, brain stem, or spinal cord to assess the risk of progression to MS. The influence on patient prognosis of HLA-DR and -DQ alleles and presentation with disseminated brain lesions, demonstrated by MRI scanning, was determined. Clinical progression to MS was observed in 61% of optic neuritis patients, 50% of patients with a brain-stem syndrome, and 35% of patients with a spinal cord disturbance. MS and the isolated clinical syndromes were positively associated with DRB1*1501, DQA1*0102, and DQB1*0602; the frequency of these alleles in the latter group was intermediate between that seen in MS patients and healthy controls. Conversion to MS was positively associated with the DRB1*1501.DQA1*0102.DQB1*0602 haplotype, but the influence of HLA was only significant in patients with disseminated brain lesions at presentation (MRI positive); MS developed in 86% of MRI-positive, DRB1*1501-positive patients compared with 55% of MRI-positive, DRB1*1501-negative patients (p < 0.025). The data suggest that these HLA alleles are involved in susceptibility to initial demyelinating lesion formation and are important in the subsequent development of MS in MRI-positive patients.

Adult↗
PubMed1993

The significance of brain magnetic resonance imaging abnormalities at presentation with clinically isolated syndromes suggestive of multiple sclerosis. A 5-year follow-up study.

A 5-year follow-up study was performed on 89 patients who had undergone brain magnetic resonance imaging (MRI) at presentation with an acute clinically isolated syndrome of the optic nerves, brainstem or spinal cord of a type suggestive of multiple sclerosis. At presentation, MRI was abnormal, revealing one or more asymptomatic cerebral white matter lesions in 57 (64%), and was normal in 32 (36%). At follow-up, progression to clinically definite multiple sclerosis had occurred in 37 out of 57 (65%) with an abnormal MRI and one out of 32 (3%) with normal MRI. Human leucocyte antigen (HLA) typing was performed in 70 patients and cerebrospinal fluid (CSF) was examined at presentation in 36. The presence of HLA-DR2 antigen or cerebrospinal fluid oligoclonal IgG bands were both associated with a significantly increased risk of progression to multiple sclerosis, but MRI was much more powerful in predicting outcome. The presence of four or more MRI lesions at presentation was associated with a higher rate of progression to multiple sclerosis, more frequent development of moderate or severe disabilities and a greater number of new MRI lesions at follow-up. The results indicate that brain MRI at presentation with a clinically isolated syndrome suggestive of multiple sclerosis is a powerful predictor of the clinical course over the next 5 years. This observation, combined with an ability to detect other sometimes treatable disorders which can also cause such syndromes, suggests that MRI is the investigation of choice in evaluating this group of patients.

Adolescent↗
PubMed1993

Relationships among academic, neuropsychological, and intellectual status in subtypes of adults with learning disability.

A study was conducted of 102 adults with learning disability for the purposes of (1) contrasting a rule-based with an empirical method of classification into subtypes based on academic achievement levels in reading and arithmetic; and (2) examining cognitive profiles obtained with the Luria-Nebraska Neuropsychological Battery and the Wechsler Adult Intelligence Scale-Revised (WAIS-R) associated with each of the rule and empirically based subtypes. Both similarities and differences were found between classification methods. Both methods indicated that specific reading disability was associated with the most impaired cognitive profiles of the three subtypes identified. However, they did not agree concerning cognitive profiles of subtypes, characterised by a specific arithmetic deficit or a global deficit. It was found that both the Lurid-Nebraska and WAIS-R profiles distinguished among subtypes more by pattern than by level of performance.

Journal Article↗
PubMed1992

Birth weight threshold for postponing preterm birth.

OBJECTIVE: The study was designed to determine the birth weight threshold at which obstetric efforts intended to delay delivery might potentially improve rates of neonatal morbidity and mortality among pregnancies delivered after spontaneous preterm labor or rupture of the membranes. STUDY DESIGN: We studied 1147 singleton infants with birth weights between 1000 and 2499 gm and whose only complication was spontaneous preterm labor or preterm rupture of the membranes. The Mantel-Haenszel chi 2 statistic was used to evaluate trends for neonatal mortality and several indexes of morbidity. RESULTS: The birth weight threshold for neonatal mortality was 1600 gm (p < 0.001). For neonatal morbidity the threshold was between 1600 and 1900 gm (p < 0.008). CONCLUSION: Aggressive obstetric attempts to prevent preterm birth for infants whose weights exceed 1900 gm offers few apparent potential benefits.

Birth Weight↗
PubMed1992

The role of drugs in the etiology of stroke.

Drugs of many classes have been implicated in hemorrhagic and ischemic stroke. Alcohol in moderation may have a protective effect although in greater doses may predispose to stroke. Drugs such as cocaine, amphetamines and heroin have been associated with stroke by a number of mechanisms. Antiplatelet, anticoagulant and thrombolytic therapy carry risk of hemorrhagic complications. Oral contraceptives appear to slightly increase stroke risk whereas estrogen replacement therapy may decrease it. Anabolic steroid use in athletes has been linked to stroke. The antineoplastic agent L-asparaginase has been associated with cerebral hemorrhage, ischemic infarction and venous sinus thrombosis. Infarction has been reported in association with cisplatin-based combination chemotherapy. Stroke is an infrequent but recognized complication of some forms of drug therapy and drug abuse.

Animals↗
PubMed1992

Rhinocerebral and nasal zygomycosis in sheep caused by Conidiobolus incongruus.

The clinical findings, pathology and mycology of a cluster of 5 ovine cases of rhinocerebral and nasal zygomycosis caused by Conidiobolus incongruus are described. All cases were in Border Leicester or Merino x Border Leicester ewes from a flock pastured in a low-lying paddock adjoining a small tidal river in subtropical Queensland (latitude 28 degrees S). These cases of zygomycosis are believed to be the first infections due to C incongruus recorded in animals other than humans. The disease was subacute in 4 animals with a course of up to several weeks. In these, the primary site of infection was the posterior nasal cavity. The lesions extended to the dorsum of the face between the eyes, to the orbital cavity and to the anterior brain and meninges in the cranial cavity. In one animal, where the anterior nasal cavity was affected and iodine treatment used, the course was longer. The fungal granulomas had numerous foreign body giant cells, neutrophils and eosinophils. Fungal hyphae were thin walled, 6 to 8 microns in diameter, with occasional septa and irregular branching. They were cuffed with a wide zone of necrotic cell coagulum, or with homogeneous eosinophilic Splendore-Hoeppli granules.

Animals↗
PubMed1992

Historical perspectives of chondromalacia patellae.

Widespread misuse of the term chondromalacia has led to confusion regarding its true meaning. This term should not be used to diagnose patellofemoral pain, but to describe lesions of articular cartilage. Recent advances using stereophotogrammetry to evaluate the patellofemoral joint and its articular cartilage may lead to new insight into the etiology of these lesions.

Cartilage Diseases↗
PubMed1992

Patellectomy.

We believe the patella should be preserved when possible and stress the significant use the patella has in normal knee function. Although alternative treatments can often be found, patellectomy may be indicated in selected patients to improve function and reduce pain.

Humans↗
PubMed1991

MR imaging of the knee: clarification of its role.

In an attempt to further delineate the role of magnetic resonance (MR) imaging in evaluating knee pathology, a retrospective study of 60 patients who underwent MR scanning before arthroscopy was undertaken. For medial meniscus tears, the sensitivity of MR imaging was 97% whereas its specificity was 77%. For lateral meniscus tears, MR imaging was 90% sensitive and 87% specific. The positive predictive value of MR imaging was 85% for medial meniscus tears and only 79% for lateral meniscus tears. The negative predictive value was 95% for the medial meniscus and 94% for the lateral meniscus. MR imaging had an accuracy of 93% in assessing anterior cruciate ligament pathology also. These results begin to clarify the role of MR imaging in evaluating intraarticular knee pathology. Grade III signals represented tears at arthroscopy more than 90% of the time. False-positive results occurred more frequently than false negative results did. The high negative predictive value of MR imaging indicates that with a negative MR image, the orthopaedist can reliably conclude that no meniscal pathology is present. MR imaging is a useful diagnostic tool; however, it should be used selectively and in conjunction with the clinical examination in evaluating internal derangements of the knee.

Adult↗
PubMed1991

Use of costal cartilage cantilever grafts in negroid rhinoplasties.

Dorsal augmentation and nasal tip refinement are important objectives in Negroid rhinoplasty. Use of a costal cartilage cantilever graft will achieve these objectives. We report on our experience in 19 patients. The technique offers an excellent solution to supplying the large amount of material often required to adequately augment the dorsum in these patients. The graft is also versatile enough to allow nasal tip refinement. There are additional aesthetic benefits as the cantilever causes a lengthening in the nasal columella, a reduction in the flare of the nostrils, and increases the columellar-labial angle. The procedure is relatively simple to perform. The problem of warping is minimized by symmetrical carving and the use of large grafts with a substantial cross-section.

Anthropometry↗
PubMed1990

Observations on the cause of oligohydramnios in prolonged pregnancy.

There is increasing evidence that implicates reduced amnionic fluid volume as a major determinant of fetal risk in prolonged pregnancy. We sought to determine whether reduced fetal urine production might be associated with oligohydramnios in pregnancies that reach 42 weeks or more. Ultrasonographic measurements of the fetal bladder were obtained every 2 to 5 minutes for 1 hour in 38 gestations verified to be at least 42 weeks. Oligohydramnios was present in eight of the prolonged pregnancies. Similar measurements were performed in 15 normal pregnancies delivered by elective repeat cesarean section between 38 and 40 weeks' gestation. Hourly fetal urine production rates were calculated with sequential bladder volume measurements. The result of this investigation suggest that diminished fetal urine production is associated with oligohydramnios in prolonged pregnancy. The mechanism by which fetal urine production is reduced in prolonged pregnancy remains unknown. A likely possibility is reduced fetal swallowing because of already diminished amnionic fluid volume, the latter a result of placental senescence.

Chi-Square Distribution↗
PubMed1990

Material properties and structure-function relationships in the menisci.

The menisci serve several important biomechanical functions in the knee. They distribute stresses over a broad area of articular cartilage, absorb shocks during dynamic loading, and probably assist in joint lubrication. These functions enhance the ability of articular cartilage to provide a smooth, near-frictionless articulation and to distribute loads evenly to the underlying bone of the femur and tibia. In addition, the menisci provide stability to the injured knee when the cruciate ligaments or other primary stabilizers are deficient. The ability to perform these mechanical functions is based on the intrinsic material properties of the menisci as well as their gross anatomic structure and attachments. The material properties of the menisci are determined by their biochemical composition and, perhaps more important, by the organization and interactions of the major tissue constituents: water, proteoglycan, and collagen. Interactions among the important constituents of the fibrocartilage matrix cause meniscal tissue to behave as a fiber-reinforced, porous, permeable composite material similar to articular cartilage, in which frictional drag caused by fluid flow governs its response to dynamic loading. The menisci are one-half as stiff in compression and dissipate more energy under dynamic loading than articular cartilage. Energy dissipation, or shock absorption, by the menisci is the result of high frictional drag caused by low permeability of the matrix, which is about one-sixth as permeable as articular cartilage. The dynamic shear modulus of meniscal tissue is only one-fourth to one-sixth as great as that of articular cartilage. The coarse, circumferential Type I collagen fiber bundles of the meniscus give the tissue great tensile stiffness (range, 100-300 megapascals) and strength. The highly oriented collagen ultrastructure of the menisci makes the tissue anisotropic in tension, compression, and shear and appears to dominate its behavior under all loading conditions.

Collagen↗
PubMed1989

Material properties of the normal medial bovine meniscus.

The intrinsic compressive and tensile properties of normal bovine medial menisci were measured, and the variations in these properties with respect to the structural organization of the tissue and test specimen location were examined. Using a confined compression experiment, the compressive aggregate modulus and permeability of the meniscus were determined. The permeability of the tissue was also compared with the permeability as measured experimentally using a direct permeation experiment. Deep posterior specimens are significantly stiffer in compression than deep anterior and central-anterior specimens, while deep anterior specimens are significantly less stiff than deep posterior and central-posterior specimens. Posterior specimens have a significantly higher average water content. In addition, the permeability of the bovine meniscus was found to be about one-tenth that of bovine articular cartilage. The tensile stiffness of meniscal tissue was determined from constant strain rate uniaxial tension tests. To asses the directional variations in the tensile properties, specimens were obtained from the circumferential and radial orientations. The results indicate that the femoral surface of the meniscus is isotropic in tension, while specimens from within the meniscus are anisotropic--the circumferential specimens are much stiffer than the radial specimens. Furthermore, circumferential posterior specimens from the interior of the meniscus are significantly stiffer than similar anterior specimens. Layer inhomogeneities in the tensile properties with respect to distance from the femoral surface are also present.

Animals↗