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Biomedical subjects

D A Wilson

Publications and source records attributed to D A Wilson.

At least 73 records · Page 4Linked to original sources
PubMed1996

Unilateral adrenal enlargement due to Histoplasma capsulatum.

Human infection with Histoplasma capsulatum runs the gamut from asymptomatic to disseminated disease. CT-directed fine-needle aspiration of bilaterally enlarged adrenal glands has been used in diagnosing serious infections with this ubiquitous organism. Three cases have previously been reported in which H. capsulatum infection caused unilateral adrenal enlargement; this enlargement was diagnosed post-mortem. We describe three patients with unilateral adrenal enlargement due to H. capsulatum whose conditions were diagnosed antemortem. We encourage clinicians to include infection with H. capsulatum as well as other granulomatous diseases and tumors in the differential diagnosis of unilateral adrenal enlargement.

Adrenal Glands↗
PubMed1996

Reduction of cytochrome-c oxidase copper precedes failing cerebral O2 utilization in fluorocarbon-perfused cats.

We determined the relationship of the low-potential copper (CuA) redox state of cytochrome-c oxidase to the brain tissue PO2 (PtiO2) and global cerebral O2 consumption (CMRO2) in vivo. The redox state of cytochrome-c oxidase copper was monitored in perfluorocarbon-exchanged cats under normoxic and graded hypoxic conditions with use of near-infrared spectroscopy. Continuous spectra ranging from 730 to 960 nm were acquired, and the change in copper redox state was assessed by the absorption changes at 830 nm. PtiO2 was measured with O2-sensitive electrodes implanted into the cortex, and CMRO2 was determined by sampling arterial and superior sagittal sinus perfusate and by measuring blood flow with radiolabeled microspheres. As PtiO2 decreased with hypoxia, the CuA of cytochrome-c oxidase became progressively reduced, whereas the CMRO2 was unchanged during the initial stages of hypoxia. Only with severe hypoxia, did CMRO2 and the amplitude of somatosensory evoked potentials decrease. We conclude that the CuA site of cytochrome-c oxidase is involved in a regulatory adjustment that helps maintain CMRO2 constant.

Animals↗
PubMed1996

Scintigraphic evaluation of 99mTc-methylene diphosphonate uptake in the navicular area of horses with lameness isolated to the foot by anesthesia of the palmar digital nerves.

OBJECTIVE: To evaluate distribution and intensity of 99mTc-methylene diphosphonate (99mTc-MDP) uptake in the navicular area in horses with forelimb lameness isolated to the palmar aspect of the foot. DESIGN: Prospective, case-controlled study. ANIMALS: 7 horses with clinical signs of navicular syndrome and 7 control horses. PROCEDURE: Palmar view, soft tissue-phase scintigraphic images of the foot were obtained between 7 and 12 minutes after injection of 120 to 170 mCi of 99mTc-MDP. Lateral and palmar view, bone-phase images were obtained at 30 minutes and 1, 2, and 4 hours after injection. Palmar views were evaluated by determining the ratio of image density in the navicular area to mean image density in the distal phalangeal area. Palmar and lateral view, bone-phase images were also scored on the basis of navicular area intensity (intense = 3, moderate = 2, mild = 1, and no uptake = 0). Density ratios and mean scores were evaluated as a three-way ANOVA. RESULTS: Mean navicular-to-distal phalangeal density ratio for affected horses (1.77) was significantly (P = 0.003) greater than that for control horses (0.97). The mean subjective score for affected horses when evaluating palmar views only (1.85) and when evaluating palmar and lateral view pairs together (1.99) was significantly (P < 0.01) higher than scores for control horses (0.51, 0.62). Images obtained 1 hour after injection were as good at differentiating affected from control horses as images obtained between 2 to 4 hours after injection. CONCLUSION: A substantial number of horses with palmar foot pain have increased scintigraphic uptake within the navicular bone 1 to 4 hours after injection of 99mTc-MDP. Lateral view, bone-phase images are less sensitive than palmar view, bone-phase images in revealing navicular area uptake. CLINICAL RELEVANCE: A combination of lateral and palmar view scintigraphic images obtained between 1 and 4 hours after injection of 99mTc-MDP is a useful diagnostic aid in evaluating navicular bone involvement in horses with forelimb lameness isolated to the palmar aspect of the foot.

Analysis of Variance↗
PubMed1996

Local distribution of mepivacaine after distal interphalangeal joint injection in horses.

OBJECTIVE: To evaluate the distribution of mepivacaine hydrochloride after distal interphalangeal (DIP) joint injection in horses. DESIGN: Prospective, uncontrolled study. ANIMALS: 10 adult horses. PROCEDURE: 30 minutes before euthanasia, 8 ml of 2% mepivacaine hydrochloride was injected into the dorsal pouch of a forelimb DIP joint. Synovial tissue from the DIP joint and podotrochlear (navicular) bursa and bone tissue from the medullary cavity of the distal sesamoid (navicular) bone were taken from both forelimbs immediately after death. All synovial and bone specimens were analyzed for tissue concentration of mepivacaine by high-performance liquid chromatography. Synovial tissue and bone specimen concentrations from the injected forelimb were compared with corresponding specimens from the noninjected forelimb. All synovial tissue and bone specimen concentrations were compared with an estimated effective tissue concentration of mepivacaine (0.3 microgram/mg) for local anesthesia. RESULTS: Specimen concentrations of mepivacaine from the injected forelimb were significantly greater (P < 0.05) than those in the corresponding tissues of the contralateral noninjected forelimb. All DIP joint and navicular bursa synovial tissue specimens from the injected forelimb had greater than the estimated effective tissue concentration of mepivacaine for local anesthesia. Of the 10 navicular bone specimens from the injected forelimb, 4 were higher and 2 were within 20% of the estimated effective tissue concentration of mepivacaine for local anesthesia. CONCLUSIONS: Mepivacaine hydrochloride deposited into the DIP joint should anesthetize pain arising from navicular bursa synovia and may decrease pain arising from the medullary cavity of the navicular bone. CLINICAL RELEVANCE: DIP joint injection of mepivacaine hydrochloride is not specific for DIP joint pain.

Animals↗
PubMed1996

In vitro and in vivo effects of activated macrophage supernatant on distal limb wounds of ponies.

OBJECTIVE: To determine whether monokines produced by activated rabbit peritoneal macrophages can inhibit development of exuberant granulation tissue formation in distal limb wounds in ponies. DESIGN: Randomized block. ANIMALS: 5 castrated male ponies, 2 to 6 years old and weighing 140 to 190 kg. PROCEDURE: In vitro activity of cell-free rabbit peritoneal macrophage supernatant was determined after incubation of fibroblasts from the flank and the distal portion of limbs of horses and ponies. Tritiated thymidine was then added, and after reincubation, radioactivity was measured. After creation of a 4-cm2, full-thickness wound on the mid dorsal aspect of each metacarpus and metatarsus of each pony, in vivo activity of the macrophage supernatant was evaluated. Biopsy specimens were collected at random sites near a border of each wound at 4, 6, and 10 weeks after creation of the wounds. Treatment effects were evaluated on the basis of presence of exuberant granulation tissue requiring excision, number of times that excision was required, total area of the wound, epithelialized area, area of granulation bed, and histologic evaluation of the biopsy specimens. RESULTS: The macrophage supernatant effectively inhibited proliferation of equine fibroblasts in vitro. No significant in vivo treatment effects were found among the 4 treatment groups. CONCLUSION AND CLINICAL RELEVANCE: Monokines from stimulated rabbit peritoneal macrophages may have potential for improving wound healing in horses and ponies because of their effective inhibition in vitro of equine fibroblast proliferation.

Analysis of Variance↗
PubMed1995

Chyloabdomen in a neonatal foal.

A 12-hour-old female standardbred foal developed signs of abdominal pain, tachycardia, tachypnoea and fever associated with chylous ascites. Small intestinal obstruction was due to segmental, mid-jejunal lymphangiectasia. Post mortem examination revealed a lack of communication between afferent and efferent lymphatic vessels in the mesenteric lymphocentre, a defect which was suspected to be congenital.

Abdominal Pain↗
PubMed1995

NMDA receptors mediate expression of one form of functional plasticity induced by olfactory deprivation.

Unilateral olfactory deprivation for the first 3 postnatal weeks results in an enhancement of granule cell mediated, feedback inhibition of mitral cells in the rat olfactory bulb. Granule cells are excited by mitral cells by both non-NMDA and NMDA receptors. The present report describes the effect of the NMDA antagonist MK-801 (0.75 mg/kg) on the expression of deprivation enhanced inhibition. The results demonstrate that (1) enhancement of lateral olfactory tract paired-pulse inhibition of evoked potentials in deprived bulbs was stimulus intensity dependent, with the greatest difference expressed at highest stimulus intensities; (2) MK-801 reduced inhibition in both undeprived and deprived bulbs in a stimulus intensity dependent manner, with the greatest reduction occurring at highest stimulus intensities; (3) MK-801 eliminated the stimulus intensity effect on inhibition in both groups; and (4) following MK-801, deprived bulbs showed the same or less inhibition than undeprived bulbs.

Animals↗
PubMed1995

Dissociation of behavioral and neural correlates of early associative learning.

Wistar rat pups were trained in an olfactory associative conditioning task on postnatal Day 6, 12, or 20. The training consisted of 20 pairings of a novel odor (peppermint) with footshock (1.5 mA, 1 s) with an intertrial interval of 3 min. Additional pups were trained in either unpaired or naive control conditions. On the day following training, pups were either tested for their behavioral response to the conditioned odor in a two-odor choice test, or injected with 14C-2-deoxyglucose and exposed to the odor for examination of olfactory bulb neural responses to the odor. The results demonstrate that, although pups at all ages learned to avoid the odor, only pups trained during the first postnatal week had a modified olfactory-bulb glomerular-layer response to the odor. These results suggest that although olfactory memory is correlated with modification of olfactory bulb glomerular layer function in newborns, these changes are not required for normal memory in older pups.

Aging↗
PubMed1995

Cat brain cytochrome-c oxidase redox changes induced by hypoxia after blood-fluorocarbon exchange transfusion.

We used rapid-scanning near-infrared (NIR) spectroscopy (730-960 nm) to study the effects of graded or acute hypoxia on cerebral cytochrome-c oxidase (cyt aa3) redox state in blood-perfluoro-carbon-exchanged cats with somatosensory evoked potential (SEP) monitoring. In graded hypoxia [10 min each at fractional inspiratory O2 concentration (FIO2) 0.9, 0.8, 0.7, 0.6, and 0.5], cyt aa3 reduction occurred at FIO2 0.6 when cerebral O2 delivery was < 3.5 ml.100 g-1.min-1. In acute hypoxia (FIO2 0.6 for 10 min), significant cyt aa3 reduction occurred from 5 to 10 min (cerebral O2 delivery 3.1 +/- 0.3 ml.100 g-1.min-1) and recovered with reoxygenation (FIO2 1.0). Cyt aa3 redox changes preceded or coincided with SEP alterations in both hypoxia protocols. These results demonstrate that cerebral cyt aa3 reduction occurs with severe reduction of cerebral O2 delivery, but no significant change in cerebral cyt aa3 redox state occurs with small reductions of cerebral O2 delivery. We conclude that substantial changes in cerebral cyt aa3 do not occur at physiological levels of O2 delivery and that current NIR clinical instruments would detect oxygen-dependent cerebral cyt aa3 redox changes only when O2 delivery is extremely compromised.

Animals↗
PubMed1995

Memory deficits in a demented patient with probable corticobasal degeneration.

Anterograde and retrograde amnesia in a patient with probable corticobasal degeneration (pCBD) and dementia were studied in a university medical center setting. The patient with pCBD and four comparison patients of comparable global mental status (Mini-Mental State Exam) who met NINCDS-ADRDA criteria for Alzheimer's disease (AD) were included. Standard neuropsychological tests of naming, intelligence, achievement, verbal fluency, anterograde and remote verbal and visuospatial memory, and motor skill learning were given. The pCBD patient exhibited a progressive asymmetric akinetic-rigid syndrome, which was unresponsive to Sinemet. His initially mild, intellectual deficits consisted of apraxia, slowed speech, and word-finding and memory difficulties. Over a 2-year period, a dementia syndrome developed, which involved more-serious deficits in praxis and naming, as well as impairments in spelling, calculation, verbal fluency, IQ, anterograde verbal and visuospatial memory, and motor skill learning. When tested by recall methods, the pCBD patient exhibited marked deficits on several tests of remote memory; however, on recognition testing, he performed normally on the Famous Faces Test and on a test of geographical knowledge, which measures remote visuospatial memory. By contrast, the four AD patients, who showed equivalent naming difficulties, less-severe fluency deficits, and normal motor skill learning, showed severe impairments in recalling and recognizing the names of famous people from photographs. A magnetic resonance imaging (MRI) scan of the pCBD patient showed marked frontal and parietal lobe atrophy and central atrophy, with ventriculomegaly that was greater on the left side of the brain. The temporal lobes were relatively spared, and the amygdalae, hippocampi, and temporal horns were of normal size.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

The D2 antagonist spiperone mimics the effects of olfactory deprivation on mitral/tufted cell odor response patterns.

Wistar rats had a single nare occluded on postnatal day 30, depriving the ipsilateral olfactory bulb of odor stimulation. The deprivation lasted for either 1-2 months (short-term) or 12 months (long-term). As previously reported, deprivation greatly reduced tyrosine hydroxylase immunoreactivity (the rate limiting enzyme for dopamine synthesis) in the glomerular layer of the ipsilateral olfactory bulb. The nare was then reopened and odor response patterns of mitral/tufted cells were examined. The proportion of mitral/tufted cell single-units responding to a single odor was enhanced by deprivation. Furthermore, the proportion of mitral/tufted cells responding to more than one odor was increased by deprivation, suggesting a decrease in discrimination. Finally, in undeprived bulbs, the dopamine D2 receptor antagonist spiperone mimicked the effects of deprivation on mitral/tufted cell odor response patterns. The results are interpreted as an activity-dependent dopamine modulation of lateral and feedback inhibition in the olfactory bulb, and are compared with similar events in the dark-adapted retina.

Animals↗
PubMed1995

Battery acid--an agent of attempted suicide in black South Africans.

Over a 36-month period 27 black adults, who had taken battery acid in apparent suicide attempts, were admitted to a major South African general hospital for assessment and treatment. There were no deaths. Patient features included limited schooling, unemployment and a male/female ratio of 2.4:1. Triggers were minor to moderate stressors (mainly domestic arguments) in 23 patients. Nine had a diagnosable psychiatric disorder and 5 required further psychiatric hospitalisation following discharge from the general hospital. The reported high mortality rate from acid ingestion was not observed; however, 4 patients required surgical intervention to deal with stricture formation. The average duration of stay was 7.6 days. There were no repeat suicide attempts during the study period.

Acids↗
PubMed1994

Management of perianal squamous cell carcinoma with permanent colostomy in a mare.

A 28-year-old Pinto mare was evaluated for multiple recurrences of a perianal squamous cell carcinoma. Clinical signs included lethargy, inappetence, weight loss, dyschezia, and hematochezia. The tumor involved the proximal portion of the vulvar labia, the perineum, and the anus, and there was a rectal fistula just left of the anus. Permanent end-on colostomy without further treatment of the carcinoma was the management option chosen. The colostomy functioned satisfactorily, and the mare's condition was stable for the next 14 months. Recurrence of lethargy and inappetence and development of weakness eventually necessitated euthanasia.

Animals↗
PubMed1994

Disseminated peritoneal leiomyomatosis in a horse.

A 6-year-old female Quarter Horse became inappetent, lost weight, was febrile, and had abdominal enlargement and infrequent bouts of mild colic. Palpation per rectum detected a prominent, smooth-walled mass adjacent to the pelvic flexure of the colon. Analyses revealed the peritoneal fluid was apparently normal except for a high protein concentration. By the use of ultrasonography, the mass was observed adjacent to the body wall in many locations throughout the abdomen, appearing as an irregular, multiloculated structure composed of innumerable cysts of various sizes with interspersed, circular hyperechoic nodules. A celiotomy was performed, and the 34-kg mass was removed. On the basis of histologic examination, a diagnosis of disseminated peritoneal leiomyomatosis was made. The horse had an uncomplicated recovery and gained weight. Further problems have not been reported and the horse subsequently gave birth to a healthy foal. A complete examination of the horse 22 months after surgery did not reveal signs of redevelopment of the condition.

Animals↗