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Biomedical subjects

M A Wilson

Publications and source records attributed to M A Wilson.

At least 289 records · Page 16Linked to original sources
PubMed1983

Partial retinal dysplasia and subsequent degeneration in a mutant strain of domestic fowl (rdd).

An inherited recessive form of retinopathy has been discovered in the domestic fowl (rdd) which is characterized by progressive deterioration of the retina, culminating in blindness by sexual maturity. Morphologically, the condition is recognizable by abnormalities in both the retinal pigment epithelium and the neural retina. Gaps in the pigment epithelium which are first detected macroscopically at nine days of incubation become larger and more numerous until the time of hatching, then disappear during the subsequent week. Undulations in the outer nuclear, outer plexiform, and inner nuclear layers are obvious by 11 days of incubation. There is a marked reduction of photoreceptors at 18 days of incubation as compared to normal controls. After hatching, the thickness of the retina decreases with age, primarily due to cell loss from the photoreceptor region and inner nuclear layer. Detachment of the atrophic retinas generally occurs in adults, and is followed in some adults by granulation and ossification of the vitreous. Problems concerning the site of the lesion are discussed.

Aging↗
PubMed1983

Release of leukotriene C4 from guinea pig trachea.

Immunological (ovalbumin) and non-immunological (calcium ionophore A23187) stimulation of guinea pig trachea induces a prolonged contraction that is enhanced by indomethacin (8.5 microM) and inhibited by nordihydroguaiaretic acid (50 microM) pretreatment of the tissue. The mediator released by the above stimuli was identified as leukotriene C4 by reverse-phase high performance liquid chromatography, and quantitated by bioassay. Indomethacin, and/or arachidonic acid (32.8 microM) did not enhance the release, whereas nordihydroguaiaretic acid reduced the contraction and release of LTC4. The results demonstrate the hitherto unproved capability of the large airways to synthesize leukotrienes and emphasize the importance of examining their role in asthma.

Animals↗
PubMed1983

Improvement in referral practices elicited by a redesigned request format.

Significantly improved clinical information was supplied by referring physicians when a redesigned referral form was introduced. Although this form provided less space, the specific questions that were included elicited an increase in the total number of words and useful clinical information that was supplied. In turn, the better clinical information helped the radiologist produce an improved report for the referring physician. These positive changes were noted with the introduction of the new form, and they persisted when the form was reevaluated 12 months later.

Forms and Records Control↗
PubMed1982

Age alters dopaminergic responses to estradiol.

Young (3-5 months) and middle-aged (17-19 months) ovariectomized rats were treated with estradiol benzoate for three days and striatal dopaminergic function was assessed behaviorally (circling in response to apomorphine) and neurochemically (binding of [3H]spiroperidol by striatal membranes). The results suggest that striatal dopaminergic function may respond differently to estrogen in older animals compared to younger animals.

Aging↗
PubMed1982

Discordance of sclerosing skeletal secondaries between sequential scintigraphy and radiographs.

Regression in metastatic lesions as seen on a bone scan may be accompanied by increasing sclerosis radiographically. There are two possible causes for interval radiographic sclerosis: progressive osteoblastic tumor deposition or the healing process itself. The presence of active neoplasia can better be determined in sclerotic lesions by the bone scan which demonstrates the tumor-induced new bone formation, as compared to radiographs which show the more unpredictable results of new bone formation plus the reparative process. Two cases are presented to illustrate the importance of bone scanning in determining whether sclerosis indicates disease progression or regression.

Bone Neoplasms↗
PubMed1982

Radiation cataractogenesis in the amphibian lens.

This report describes a reproducible and characteristic sequelae for radiation cataractogenesis in the amphibian. The development of lens opacification was investigated as a function of dose and time after X-irradiation of the eye of postmetamorphic bullfrogs. It was found that the development of radiation cataracts in frogs is both age and dose dependent. It was also determined that, far from being radiation resistant, frog lenses are sensitive to doses that are moderately cataractogenic for mammals.

Age Factors↗
PubMed1981

Diurnal rhythm of cytoplasmic estrogen receptors in the rat brain in the absence of circulating estrogens.

The concentration of cytoplasmic estrogen receptors in the brain of ovariectomized female rats varies during the light-dark cycle. There is no variation in the affinity of the receptors for estradiol, and the rhythm is not due to estrogens from nonovarian sources. Pentobarbital reverses the reduction of receptors that occurs in the dark, and melatonin injection in the light partially mimics the action of darkness in reducing receptor levels. The factors that cause this rhythm is brain estrogen receptors may be one means by which light affects reproductive function.

Adrenalectomy↗
PubMed1981

Correction of respiratory motion in hepatic scintigraphy.

An analog device to correct for respiratory motion was used in 100 consecutive liver scans to determine its clinical utility. The sets of scan images generated were reviewed separately, then together, without knowledge of clinical presentation or imaging technique. When the images were reviewed separately, there was no clinical significant change in patient classification. When the images were reviewed together, 57% of the patients had detectable differences in image features, and in most instances this difference was limited to a clearer definition of organ outline or normal variants (e.g., gallbladder fossa). Of the 17 patients with focal hepatic disease, 14 had these defects better defined or additional lesions identified. Of the 18 patients with definite, diffuse, nonhomogeneous tracer distribution as seen in the uncorrected images, 12 had changes in scan appearance with motion correction. In eight patients the scan pattern became more normal, but in four the abnormal pattern was modified to that of focal defects.

Humans↗
PubMed1981

Scintigraphic assessment of heterotopic cardiac transplants.

Patients receiving heterotopic ("piggyback") cardiac transplants, when the patient's own and transplanted donor hearts are connected in parallel, present special problems in determining their relative contributions to total cardiac function. Three patients who had transplants because of intractable heart failure were studied using first pass and gated equilibrium technetium-99m-labeled blood pool scintigraphy. In one patient, thallium-201 myocardial perfusion scans were obtained. These nuclear cardiology techniques provided anatomic and functional information noninvasively that proved helpful in patient management.

Adult↗
PubMed1981

Gastric visualization and image quality in radionuclide bone scanning: concise communication.

In a 12-mo study period, there were 14 days identified when the stomach was visualized in routine bone imaging. On these days, 44% of the 110 patients imaged demonstrated this effect. Only the quality control, binding efficiency, and scan quality differed (p less than 0.005) when the study population was compared with a reference population of 162 patients. However, on the days when this effect was noted, there was a significant (p less than 0.001) linear correlation between the presence and degree of gastric visualization and the radiopharmaceutical incubation and quality control parameters. The study suggests a sporadic phenomenon that appears to result from partial oxidation of the agent during incubation, producing (a) different species of labeled diphosphonate that display altered affinity for bone (scan quality) and (b) free pertechnetate (gastric activity).

Bone and Bones↗
PubMed1981

The distribution of skeletal metastases in breast and pulmonary cancer: concise communication.

In a review of all radionuclide bone scans performed in a 3-mo period, 318 patients with established tumor diagnosis were studied. In this tumor population the incidence of skeletal metastases was statistically similar (p = 0.7), and regional distribution of lesion involvement was, in decreasing order, thorax, spine, pelvis, limbs, and skull. In the two largest tumor groups (breast and lung) the regional distribution of metastases was not different when examined for both the presence and the number of lesions (p greater than 0.1). In particular, the incidence of rib metastases was similar( p greater than 0.99) as was their frequency distribution (0.78). Indeed, the frequency distribution of rib metastases was similar for all major tumor categories (p = 0.83).

Bone Neoplasms↗
PubMed1980

Growth of a limb spinal nerve: an ultrastructural study.

A quantitative study of the delivery of nerve fibres to the developing limb has been made. Electron microscope (EM) sections of SN 9 in Xenopus were taken at close intervals between dorsal root ganglion and limb-bud. Numbers and types of axons in each section were counted. Counts declined steadily with distance from the ganglion towards the base of the limb. This is large due to some axons not having grown the full distance at the time of fixation. The slope corresponded with an outgrowth velocity of 0.5 mm a day, without branching. Distally, at stages 50 and 51, but not at stages 49 and 54, the decline was reversed, and a peak of axon number was found. This is strong evidence for axon branching in this region. Since this took place at least one stage before SN 9 bifurcated, and since the bifurcation was distal to the branching when it did appear, it is suggested that axon branching at a nerve bifurcation might be part of a trial-and-error mechanism for pathway selection. Observations were made on the sheath surrounding the nerve, and on its assembly. Initially, axons grow out naked and not parallel; Schwann cells migrate after the growing front. Processes of these cells collect individual axons, and transfer them inwards to form the primitive parallel fibre bundle, enclosed by a family of Schwann cells. Myelination later occurs in a similar manner: Schwann-cell processes extend into a bundle of naked axons and eventually encircle a single transitional axon, with one Schwann cell eventually containing many such axons. Finally comes the stage of promyelin, in which a single Schwann cell encircles a single axon. Myelin whorls are then formed from this complex.

Animals↗