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Biomedical subjects

D Osborne

Publications and source records attributed to D Osborne.

At least 37 records · Page 2Linked to original sources
PubMed1995

Progressive apraxia in clinically discordant monozygotic twins.

OBJECTIVE: To determine disease concordancy in the first identical twin with corticobasal degeneration. The patients were 63-year-old, erythrocyte antigen-confirmed monozygotic male twins who were clinically discordant for progressive apraxia caused by corticobasal degeneration. INTERVENTIONS: Neuropsychologic and kinesiologic testing, magnetic resonance imaging, and positron emission tomographic measurements of cerebral metabolic rate for glucose. RESULTS: The affected twin had lower neuropsychologic and kinesiologic test scores than did his brother, particularly on tests sensitive to right-compared with left-hemisphere function; widespread cerebral atrophy, worst in right parietotemporal cortices; and reduced whole-brain cerebral metabolic rate for glucose, worst in right posterior cortices. The clinically asymptomatic twin had normal neuropsychologic and kinesiologic test scores but performed more poorly on tests sensitive to left- compared with right-hemisphere function; had no abnormalities on magnetic resonance imaging; and had left temporoparietal as well as mild whole-brain hypometabolism. CONCLUSIONS: Corticobasal degeneration may remain clinically discordant in identical twins after 7 years. Positron emission tomography and neuropsychologic findings suggest the possibility of a preclinical stage of corticobasal degeneration. There is generalized cortical atrophy in patients with corticobasal degeneration in addition to focal atrophy.

Apraxias↗
PubMed1995

Primary lateral sclerosis: a neuropsychological study.

Nine patients with clinically diagnosed, radiologically supported primary lateral sclerosis underwent cognitive testing. None was demented, but eight had mild cognitive impairment. Performances were most consistently impaired on neuropsychological tests sensitive to frontal lobe functions, followed by tests sensitive to memory. Cognitive testing may be useful in helping to establish a cortical localization in patients with the syndrome of progressive spasticity. There are potential nosologic relations between primary lateral sclerosis and other degenerative frontal lobe syndromes, such as frontal lobe dementia and progressive spasticity with dementia.

Adult↗
PubMed1995

No postural effect on middle ear resonance frequency: a pilot study.

A change in body posture from sitting to reclined is known to cause an increase in intracochlear fluid pressure, if the cochlear aqueduct is patent. Previous studies have shown this increase to have an effect on middle ear dynamics. The aim of this study was to investigate whether such increases in cochlear pressure may affect the stiffness of, and hence the resonance frequency of the middle ear. No consistent group or individual differences were shown between the two postural conditions.

Acoustic Impedance Tests↗
PubMed1994

Levels of burnout in general dental practitioners in the south-east of England.

There is some evidence to suggest that dentists suffer a high level of job-related stress. Specifically, social interaction between dentist and patient is considered to be a type of job-related stress which may produce 'burnout', a syndrome of emotional exhaustion, depersonalisation and reduced personal accomplishment that can occur in individuals whose work involves close personal contact with their clients. A study was carried out during January to June 1992 to assess the levels of burnout, using the Maslach Burnout Inventory, in three samples of British GDPs recruited from the south-east of England. A total of 440 dentists were surveyed and 340 usable replies were returned. There were high levels of burnout in the British dentists. A number of demographic variables relating to marital status, educational status, time since qualification, numbers of dentists in the practice, number of days per week spent in practice and the proportion of NHS/private work undertaken were identified as being associated with some aspects of the burnout syndrome.

Burnout, Professional↗
PubMed1994

Spinal cord ischemia and reperfusion metabolism: the effect of hypothermia.

PURPOSE: The metabolic and neurologic functional effects of regional hypothermia induced by cold (4 degrees C) heparinized saline perfusion on spinal cord ischemia were evaluated in 35 rabbits. METHODS: Spinal cord ischemia was induced for 20 minutes by infrarenal aortic occlusion in anesthetized animals. Regional spinal cord hypothermia was obtained by perfusing the lumbar arteries supplying the spinal cord through an infrarenal aortic catheter. The lumbar spinal cord was "snap frozen" in situ with liquid nitrogen and harvested immediately at the conclusion of the ischemic period or after 24 hours of normothermic reperfusion and neurologic observation. Spinal cord metabolic studies included determination of the energy charge and the intracellular concentrations of adenosine triphosphate, glucose, lactate, glutamate, and aspartate. RESULTS: Postoperative neurologic function was normal in all but one animal treated with hypothermia, while normothermic ischemia resulted in paralysis in all animals (p = 0.002). Spinal cord temperature during 20 minutes of ischemia and hypothermic perfusion decreased from 37.5 degrees +/- 0.43 degrees C to 22.8 degrees +/- 0.00 degrees C (p = 0.0001) compared to a fall in systemic temperature from 38.8 to 36.1 (p = 0.0001). Hypothermia reduced the decline in energy charge, adenosine triphosphate concentration and glucose concentration during ischemia but had no effect on markedly elevated levels of lactate acid. High-energy phosphates were restored after reperfusion in both normothermic and hypothermic animals and were not predictive of postoperative paraplegia. Intracellular glutamate and aspartate concentrations were unchanged during normothermic ischemia but decreased after reperfusion in all paralyzed animals. Intracellular glutamate and aspartate concentrations increased during hypothermic perfusion and remained elevated after reperfusion in animals with a normal or mildly abnormal neurologic examination result. CONCLUSIONS: We conclude that spinal cord hypothermia induced by cold heparinized saline perfusion is a simple technique that prevents paraplegia after 20 minutes of ischemia and preserves intracellular concentrations of important metabolites.

Adenosine Triphosphate↗
PubMed1994

Early changes in the sulfation of chondroitin in guinea-pig articular cartilage, a possible predictor of osteoarthritis.

Male Dunkin Hartley guinea-pigs have been shown to develop spontaneous osteoarthritis, in the knee joint, which is histologically apparent from the age of 3 months onwards. We have used capillary electrophoresis (CE) to examine subtle changes in the sulfation of chondroitin in guinea-pig articular and xiphisternal cartilage. An age-related increase in the 6:4 sulfation ratio of chondroitin was observed, with the medial tibial plateau developing more rapidly than the other joint surfaces. The observed sulfation patterns may be related to the onset of spontaneous osteoarthritis which, in the guinea-pig, develops initially on the medial tibial plateau. Chondroitin from patellar groove cartilage of animals between 3 and 12 months of age always had a significantly lower 6:4 sulfate ratio than the other joint surfaces.

Animals↗
PubMed1994

In vivo proton spectroscopy of intracranial infections and neoplasms.

The chemical characteristics of 10 neoplastic and 11 infectious brain masses were studied by in vivo 1H magnetic resonance spectroscopy. In tumors, peak height ratios of n-acetyl-L-aspartate to choline were decreased compared to those in normal brain tissue and infectious masses (p < 0.02), but the ratios in normal brains and those with infections did not differ. N-acetyl-L-aspartate-to-creatine/phosphocreatine ratios were significantly lower in infectious masses and tumors compared to normal brain tissue (p = 0.003). However, in progressive multifocal leukoencephalopathy, N-acetyl-L-aspartate appeared relatively unchanged. Lactate was greater than choline in 9 of 11 brains with infection, 0 of 14 control brains, and 1 of 10 tumors. Lactate-to-choline ratios were significantly elevated in infectious masses compared with tumors (p < 0.01). 1H magnetic resonance spectroscopy is promising for the noninvasive diagnosis of focal brain masses.

Analysis of Variance↗
PubMed1993

Pain relief after arthroscopic surgery of the knee: a prospective, randomized, and blinded assessment of bupivacaine and bupivacaine with adrenaline.

A prospective, randomized, and double-blind study was conducted to compare the influence on postoperative pain of equal volumes of saline, bupivacaine, or bupivacaine with adrenaline, injected both intraarticularly and into the wound puncture site, for 118 day case patients undergoing elective knee arthroscopy. Marginal analyses of postoperative visual analogue pain scores and postoperative fentanyl doses showed that the group given bupivacaine with adrenaline had less postoperative pain when compared with the saline group. However, when multifactor analyses were performed, preoperative visual analogue pain scores, operation type and length, and the sex of the patient were all shown to be significant predictors of postoperative pain, but the use of bupivacaine was not. We conclude that the observed differences in postoperative pain were due to differences between the groups in these predictive factors, especially preoperative pain scores, and that the use of bupivacaine was less important and not statistically significant in influencing postoperative pain.

Adult↗
PubMed1991

Variation in resistance to herpes simplex virus type 1 of oligodendrocytes derived from inbred strains of mice.

Primary oligodendrocyte (OL) cultures from three inbred strains of mice with known differences in resistance to herpes simplex virus type 1 (HSV-1) infection in vivo (A/J, susceptible; BALB/cByJ, moderately resistant; C57BL/6J, resistant), also display a similar pattern of resistance in vitro. The nature of the in vitro resistance at the cellular level was investigated. Virus production at different m.o.i.s indicated that the differences in HSV-1 replication are m.o.i.-dependent. Overall, virus yield from the OL cultures infected at a multiplicity of 1 increased 48 h post-infection (p.i.); no additional enhancement occurred 72 h p.i. However, the difference in the replication capacity of the three OL cultures observed at 24 h p.i. persisted at 48 and 72 h p.i. Serial electron microscopy studies on infected OL cultures derived from the different murine strains suggested that the resistance to HSV-1 infection occurs at different stages during the replicative cycle. Virus was detected at the nuclear membrane 5 min p.i. in A/J cells, but was not observed until 120 min p.i. in BALB/cByJ cells, whereas virus could not be detected at the nuclear membrane of C57BL/6J cells, even at 24 h p.i. Virus adsorption, determined by assay of residual non-adsorbed virus infectivity and cell-associated, radiolabelled HSV-1, did not differ in the OL cultures. The cumulative data suggest that A/J cells display the same replication pattern as permissive CV-1 cells, whereas the major replicative blocks in the other two murine strains occur at the level of the cytoplasmic membrane in C57BL/6J OLs, and at the level of the nuclear membrane in BALB/cByJ cells.

Adsorption↗
PubMed1989

Phagocytic activity of human adult astrocytes and oligodendrocytes in culture.

The phagocytic activity of human glial cells was examined in primary cultures obtained from normal human brain obtained at autopsy. Highly enriched cultures of astrocytes and oligodendrocytes were established using an enzyme digestion-Percoll density gradient method. These cultures were exposed to medium containing carbon particles (indian ink) for one-24 hours. Under phase contrast and immunofluorescence microscopy, carbon particles were demonstrated in the cytoplasm and processes of both astrocytes and oligodendrocytes. Electron microscopic examination revealed carbon particles phagocytized and segregated in these cells. These findings may support a view that both astrocytes and oligodendrocytes participate in phagocytosis in certain neurological diseases.

Astrocytes↗
PubMed1988

Evaluation of memory and language function pre- and postthalamotomy with an attempt to define those patients at risk for postoperative dysfunction.

Memory and language dysfunction has been sporadically reported following stereotaxic thalamotomies. In order to determine which patients are at greatest risk and to better define the nature of this dysfunction, we have prospectively evaluated 18 patients undergoing stereotaxic thalamotomies for movement disorders (MDs). Patients were evaluated clinically, with computed tomography (CT) and with memory and language protocols (MLPs) pre- and postoperatively. Patients exhibiting postoperative deficits were again evaluated with the MLP on follow-up visits to the clinic. Significant changes in memory and language function occurred in 7 out of 18 patients. These 7 patients had diverse etiologies for their MDs. Five of the 18 patients had undergone previous thalamotomies on the contralateral side. Three of these 5 patients with bilateral thalamotomies experienced postoperative functional impairments in memory and language while only 4 of 13 patients with a unilateral thalamotomy experienced these problems. The postoperative functional impairments noted were primarily those requiring orientation and speech. All patients with postoperative memory and language impairments were again evaluated with MLPs months after the operation. In 3 of 7 patients, no improvement was noted, while the remaining 4 did recover to baseline. More severe deficits tended to occur in those patients with ventriculomegaly or evidence of other major cerebral tissue loss by preoperative CT scan and in those patients with lower MLP scores preoperatively. Postoperative memory and language dysfunction was not correlated with the number or size of the lesions made, the postoperative general neurologic examination or CT scans, or the clinical response of the MDs. From our data, it appears that patients with more profound neurologic compromise and/or bilateral involvement as evidenced by poor performance on the MLP, tissue loss on CT scanning, or previous thalamic lesion, are most at risk for memory and language dysfunction postoperatively. However, this dysfunction is not necessarily permanent. Preoperative evaluation with MLPs and CT scanning appear to be of value in predicting those patients at greatest risk for postoperative and language dysfunction.

Adolescent↗
PubMed1988

Dust emissions in cattle feedlots.

Dust emissions were measured at three Texas cattle feedlots on 15 occasions in 1987 to determine concentrations of total suspended particulate matter (TSP) and dust with 10 microns or less aerodynamic particle size (PM-10). Net feedlot dust concentrations (downwind minus upwind) ranged from 15.7 to 1,700.1 micrograms per m3 and averaged 412.4 +/- 271.2 micrograms per m3, which is about 37 per cent less than was determined in feedlot dust research in California approximately 17 years earlier. Upwind concentrations averaged 22 per cent of the downwind concentrations. Feedlot dust concentrations were generally highest in early evening and lowest in early morning. Using the Wedding and Andersen-321A PM-10 samplers, the PM-10 dust concentrations were 19 and 40 per cent, respectively, of mean TSP concentrations in direct comparisons. There was good correlation between PM-10 and TSP concentrations. Although dust concentrations decreased with increasing moisture, the correlation coefficients were relatively low. Odor intensity appeared to increase with decreasing net dust concentrations, perhaps due to moisture influences. Mean particle sizes of feedlot dust were 8.5 to 12.2 microns on a particle volume basis and 2.5 to 3.4 microns on a population basis. Respirable dust (below 2 microns) represented only 2.0 to 4.4 per cent of total dust on a particle volume basis. Under conditions of these experiments, the feedlots often exceeded both state and federal (U.S. Environmental Protection Agency) standards for TSP concentrations and for PM-10 concentrations measured using the Andersen-321A sampler. However, feedlots were below the new U.S. Environmental Protection Agency standards when the Wedding PM-10 sampler was used for measuring dust emissions.

Animals↗
PubMed1987

Hormonal regulation of gluconeogenesis in cultured proximal tubular cells: role of cytosolic calcium.

Gluconeogenic competence of primary cultures of canine renal proximal tubular cells has been examined. Cells grown in 5 mM glucose media or in glucose-free media exhibited pyruvate-stimulated glucose production, as opposed to cells grown in 20 mM glucose media. By 72 h after the last media change, confluent cells grown in 5 mM glucose medium turn from a predominantly glycolytic to an oxidative type of metabolism. By this time, glucose production exhibited pH, 3-mercaptopicolinate, and insulin sensitivity. Parathyroid hormone, angiotensin II, and phenylephrine stimulated glucose production in a nonadditive fashion. Single-cell cystolic Ca2+ measurements using microspectrofluorometric techniques revealed that all three hormones elicited Ca2+ transients in proximal tubular cells. Ionomycin stimulated glucose production by proximal tubular cells, suggesting that Ca2+ transients could represent a sufficient stimulus for glucose production. When hormone-induced Ca2+ transients were curtailed by a pretreatment with the membrane-permeant Ca2+ chelator, Maptam, hormonal stimulation of glucose production was abolished, suggesting that Ca2+ transients represent not only a sufficient, but a necessary event in the stimulation of glucose production by these hormones.

Adenosine Triphosphate↗
PubMed1987

Conus medullaris nerve root avulsions.

The association of avulsive lesions and pain has been well established in avulsions of the brachial plexus from the cervical spinal cord, but avulsive lesions of the conus medullaris have not previously been recognized or documented by direct observation. Six patients with intractable lower-extremity pain due to avulsion of nerve roots from the conus medullaris were treated by thoracolumbar laminectomy and dorsal root entry zone (DREZ) lesions. Patients with avulsion of lumbosacral roots from the conus medullaris have a characteristic clinical presentation. They are usually young men who, as a result of a motorcycle accident, have suffered multiple pelvic or long-bone fractures or traumatic amputation of part of the lower extremity. Early in their course there is pain not directly attributable to the injured part. The pain is described as intense and burning, with episodic radiation and electric shock-like sensations in the injured or phantom limb. If the leg is intact, there is usually a dermatomal pattern to the distribution of the pain and neurological deficit. A myelogram often reveals a traumatic pseudomeningocele similar to those seen in the cervical region after avulsion of the brachial plexus. Surgical exploration of the conus medullaris usually reveals the extent of nerve root avulsion, and an appropriate DREZ operation can be performed.

Adult↗
PubMed1986

Normative tables for the F-K index of the MMPI based on a contemporary normal sample.

Recent work with the F-K index of the MMPI has reaffirmed its usefulness for identifying dissimulation. However, the potential usefulness of any index of malingering is dependent on its frequency of occurrence in the normal population. This article presents normative tables for the F-K index based on a contemporary normative sample of 335 normal women and 304 normal men.

Adult↗
PubMed1986

Further experience utilizing the Gildenberg technique for computed tomography-guided stereotactic biopsies.

Initial experience using the Gildenberg technique for computed tomography-guided stereotactic biopsies is reviewed. Of 50 patients, adequate tissue was obtained in 49. In one patient, the stereotactic frame was unable to reach the selected biopsy site. In 32 of 49 patients, the diagnosis was obtained with one biopsy; in the remainder, two to five samples were required. In 4 cases, a subsequent craniotomy was performed; these provided similar histopathological tissue and in no case was the diagnosis altered. The lesions were categorized by CT as ring-enhancing lesions (REL), enhancing lesions with surrounding low density (ELLD), and low density lesions with and without peripheral areas of enhancement. Of the REL, 21 of 23 were primary tumors. Of the ELLD, 5 of 13 were primary tumors; the remainder had a wide spectrum of disease. Of the low density lesions without enhancement, 6 were primary tumors and 1 was an inflammatory process. Three patients had low density lesions with peripheral areas of enhancement and proved to have malignant primary tumors. The remaining patients had multiple lesions with both primary and metastatic disease. Twelve RELs were biopsied in multiple sites. An accurate diagnosis was best obtained by performing the first biopsy in the enhancing rim with additional biopsies as needed in the low density center. Homogeneous lesions could be biospied with target selection based upon a primary regard for safety rather than imaging characteristics. Three patients had transiently increased hemiparesis and one had a transient decrease in level of consciousness after biopsy.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1985

Using the 1983 norms for the MMPI: code type frequencies in four clinical samples.

MMPI responses obtained from a large random sample of midwestern adults who were 18 through 99 years old and had no physically or mentally handicapping condition yielded a pattern significantly different from the pattern of the original norms. From these data, two new kinds of normative tables have been developed: Norms that reflect, for each sex, the response pattern of the general adult population, and a set of tables, separate for each sex, that allow comparisons to be based on age. In addition, the traditional scoring procedures based on a linear transformation that maintains any underlying skewness of the raw score distribution has been replaced by procedures that yield normalized T scores. The changes that are apparent at the item and scale level are also evident in the frequency with which certain 1- and 2-point codes occur in normal and clinical samples. These changes are apt to make our interpretive statements more meaningful because they are based on contemporary norms.

Adolescent↗