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Biomedical subjects

H Duncan

Publications and source records attributed to H Duncan.

At least 37 records · Page 2Linked to original sources
PubMed1988

The erosive front: a topographic study of the junction between the pannus and the subchondral plate in the macerated rheumatoid metacarpal head.

The junction between cellular pannus and cartilage/bone was identified grossly on rheumatoid metacarpal heads. Its topography was displayed by scanning electron microscopy using macerated samples. A uniform pattern of resorption bays, typical of osteoclastic activity, was seen spreading over the surfaces of both calcified cartilage and subchondral bone. The contact area between pannus and cartilage/bone was found to represent an erosive front. Morphologic evidence suggested that osteoclasts were primarily responsible for the destructive process.

Adult↗
PubMed1987

Dietary sodium intake of infants fed commercially prepared baby food and table food.

Sodium intake of infants varies widely with the type of food consumed. However, few reports are available describing the nutrients, including sodium values, of dietary intakes of infants receiving supplemental foods. The purpose of this study was to determine the sodium, energy, and nutrient values of diets for infants from low-income families participating in the WIC program. The sample consisted of 306 infants, aged 4 through 7 months, who were seen in well-child clinics. Approximately 200 of the infants were reportedly fed commercially prepared baby food as the only solid food; 55 received 50% or more of their energy from table foods. The dietary intakes of infants receiving supplemental foods and consuming commercially prepared baby foods included significantly less sodium than the intakes of infants fed primarily table foods. As a group, all infants met the RDAs for most nutrients but had higher sodium values than reported by other researchers. The group of infants for whom consumption of table foods was reported had values above the acceptable range for sodium primarily because the caregivers failed to provide low-sodium, nutrient-dense, supplemental foods in the quantities prescribed but instead substituted sodium-dense meat and vegetable products.

Animals↗
PubMed1987

Older pregnant women and adolescents: nutrition data after enrollment in WIC.

Although there has been an increase in pregnancy in women over 35 years of age, the literature contains no information on dietary intakes of older pregnant women. Several studies have reported the nutritional status of pregnant adolescents who are considered to be at nutritional risk. This study investigated the energy, nutrient, and food intake patterns of 63 low-income pregnant women over 35 compared with 526 pregnant adolescents. Nutrient intake was assessed using a standardized 24-hour dietary recall protocol. Energy values for both groups were below recommended levels, and neither group gained the recommended amount of weight. Obesity may have been the reason for the lack of weight gain by the older pregnant women, since more than 50% of the older pregnant women were calculated to be obese prior to pregnancy. The younger women reported consuming less milk but more snack foods with lower nutrient densities, which significantly increased their energy values over those of the older group. In comparison with diets reported in other studies, the diets of the older pregnant women were more nutrient dense for most nutrients. Although all participants were enrolled in WIC, an equal number of women from both groups stated that they did not have the supplemental foods in their households at the time of interview.

Adolescent↗
PubMed1987

The tibial subchondral plate. A scanning electron microscopic study.

Non-arthritic tibial plateaus were obtained from fifteen cadavera and five above-the-knee amputation specimens. After radiographs had been made, each sample was macerated and the topography of the subchondral plate was displayed by scanning electron microscopy. The surface features included small peripheral and submeniscal osteophytes, indentations, and holes penetrating the plate. The pattern of distribution of holes per square centimeter was different for the subchondral plate of the medial plateau than it was for that of the lateral plateau. More holes were present in the submeniscal area of the medial tibial plateau; the lateral tibial plateau showed a greater concentration of holes in its central area. By light microscopy, many holes were seen to be blood vessels that were lined by endothelium and contained erythrocytes.

Adult↗
PubMed1986

Incidence of the radial steal syndrome in patients with Brescia fistula for hemodialysis: its clinical significance.

The Brescia fistula is the method of choice for providing vascular access in patients who have chronic kidney failure that requires hemodialysis. This study investigated hand hemodynamics in patients with Brescia fistulas to determine the incidence of radial steal and its relationship to symptoms of arterial insufficiency of the hand. Twenty-three patients, one of whom had symptoms of arterial insufficiency, were studied. Thumb systolic blood pressure was determined by photoplethysmography under resting conditions and with the fistula, radial, and ulnar arteries occluded successively by digital pressure. The brachial pressure was determined by Doppler ultrasonography and the thumb/arm pressure ratio was determined for each experimental condition. The presence of a Brescia fistula resulted in a 40% reduction of the thumb blood pressure (median thumb/arm ratio = 0.61), which returned to normal (median ratio = 1.03) when the fistula was occluded. Occlusion of the radial artery distal to the fistula resulted in a significant increase in thumb blood pressure (median ratio = 0.89; p less than 0.001), indicating the presence of radial steal. This phenomenon occurred in 21 of the 24 fistulas (88%) studied. This study demonstrated that the radial steal phenomenon occurs in most patients with Brescia fistulas but in only a small number of these patients do symptoms of arterial insufficiency develop.

Adult↗
PubMed1985

Skin perfusion pressure in the prediction of healing in diabetic patients with ulcers or gangrene of the foot.

The measurement of skin perfusion blood pressure (SPP) estimated by an isotope clearance technique has been used to predict the healing of ulcers or gangrene of the foot in 61 diabetic subjects. Healing followed conservative treatment or local surgery in 1 of 21 cases if the SPP was less than 40 mm Hg but in 35 of 40 with higher values for SPP. Healing was unlikely if the toe blood pressure was less than 40 mm Hg or the ankle systolic pressure was less than 80 mm Hg. It is recommended that the SPP be measured in patients in whom confident predictions of healing cannot be made on the basis of ankle pressure or other measurements.

Adult↗
PubMed1984

Vascular disease and vascular function in the lower limb in diabetes.

This review examines the pathology, clinical effects and physiological disturbances produced by vascular disease and autonomic neuropathy in the lower limb in diabetic subjects. Atherosclerosis is a major factor in causing foot lesions in diabetics. The distribution of the disease frequently makes vascular reconstructive surgery difficult or impossible but an aggressive approach to reconstruction is justified because the results of major amputations are bad. Arterial calcification probably has no significant effect on the blood supply to the foot. There is some evidence that disease of arteries in the foot may be associated with the development of ulcers or gangrene. Disease of the arterioles and capillaries is frequent, but there is little evidence that this microangiopathy causes lesions. Autonomic neuropathy affecting the limb is also common, and although there are several mechanisms by which this might predispose to ulcers or gangrene, there is little evidence of such a direct relationship. In a patient presenting with ulceration or gangrene of the foot it is often impossible to determine the relative roles of vascular disease, affecting large or small vessels, and neuropathy, either somatic or autonomic, in the development of the lesion. Further progress depends on the development of more direct methods for assessing microvascular and autonomic nervous function.

Arteriosclerosis↗
PubMed1983

Neurological deficit and injuries involving the neck arteries.

The management of 85 patients with penetrating injuries involving the external (n = 19), internal (n = 6) and common carotid (n = 46), vertebral (n = 10) and brachiocephalic (n = 4) arteries over a 5-year period in one hospital is reviewed. Sixty-three patients had no peroperative neurological deficit; 22 presented with localizing neurological signs. Where there was no deficit, the external carotid (n = 19) and vertebral (n = 10) arteries were ligated without adverse sequelae. Arterial reconstruction was performed of the internal carotid (n = 2) which resulted in a temporary neurological deficit in 7 patients and death in 3. Among the 22 patients with a preoperative neurological deficit, arterial reconstruction was performed in 18, which involved the common carotid in 17 patients and the internal, carotid in 1 patient. There was complete neurological recovery in 11 patients and 2 patients died. Four comatose patients had cerebral revascularization performed without fatality and with complete recovery in 3 of them. CT head scanning was not routinely employed for logistic reasons but has proved of limited value. No intraluminal arterial shunts were used in this series. It would seem that arterial reconstruction is not harmful and may well be beneficial to the young patient with extracranial cerebral arterial injury associated with a neurological deficit. Shunts are probably unnecessary for routine use.

Adolescent↗
PubMed1983

Cellular mechanisms of bone damage and repair in the arthritic joint.

Trabeculae and subchondral bone have been studied by scanning electron microscopy (EM) and fluorescence microscopy from joints removed surgically in patients with rheumatoid arthritis (RA), osteoarthritis (OA), and "normals" who had leg amputations with no primary arthritis. In the arthritic specimens, inflammation, bone damage and repair varied in different areas of the same joint. Osteoclasts and mononuclear cells were associated with areas of resorption--together and separately. Scanning EM showed trabeculae in RA to be thinner, narrower, fewer, and with spindle forms compared with thicker trabeculae in OA. Attempts at repair were more successful in OA despite the higher bone turnover which occurred locally at the rheumatoid joint.

Arthritis, Rheumatoid↗
PubMed1981

Cervicomediastinal arterial injuries. A surgical challenge.

The initial clinical observations and methods and results of treatment in 104 patients with subclavian (48), vertebral (four), and carotid (52) artery injuries are reported. Delayed hemorrhage ten days after misdiagnosed subclavian artery injuries resulted in false aneurysms causing compressive brachial plexus palsies. A conservative approach to penetrating cervicomediastinal wounds was adopted with selective use of arch aortography when arterial injury was suspected by defined criteria. This proved safe, accurate, and invaluable for planning operative approach. Partial median sternotomy without entering the pleura proved optimal for superior mediastinal access; simple clavicle transection provided adequate distal subclavian exposure. External carotid and vertebral arteries were ligated. No shunts were employed for common and internal carotid repair. None of the 14 patients revascularized in the presence of a neurologic deficit died and none was made worse by carotid reconstruction.

Adolescent↗
PubMed1980

GABA induces behavioral and developmental metamorphosis in planktonic molluscan larvae.

Swimming planktonic larvae of the marine gastropod mollusc Haliotis rufescens require exogenous GABA or its homologs for induction of their genetically programed behavioral and developmental metamorphosis to the adult form. This requirement is stereochemically specific and absolute; GABA at 10(-6) M is fully effective in the induction of cellular differentiation, proliferation and organogenesis. The kinetics of the development of larval competence for GABA induction, and of the early metamorphic processes induced by GABA, are described. Biochemical, histological and electron micrographic analyses suggest that cyclic AMP, calcium, and a glycopeptide secretion from the cephalic sensory complex may mediate transduction of the GABA signal in the control of behavioral and morphogenetic changes induced by this environmentally deployed transmitter substance. This first observation and characterization of a major role for GABA in the control of differentiation and development, and the experimentally tractable system in which these are demonstrated, are of significance for further biomedical research.

Animals↗
PubMed1977

Hydrogen peroxide induces spawning in mollusks, with activation of prostaglandin endoperoxide synthetase.

Addition of hydrogen peroxide to seawater causes synchronous spawning in gravid male and female abalones, and certain other mollusks as well. This effect is blocked by exposure of the animals to aspirin, an inhibitor of the enzyme catalyzing oxidative synthesis of prostaglandin endoperoxide. Hydrogen peroxide activates this enzymatic reaction in cell-free extracts prepared from abalone eggs (a very rich source of the prostaglandin endoperoxide synthetase); this effect appears to reveal a fundamental property of prostaglandin endoperoxide synthesis. Applicability of these findings to both mariculture and medical purposes is suggested.

Animals↗
PubMed1975

Synovial fluid analysis.

Synovial fluid analysis plays an important role in the differential diagnosis of various forms of arthritis. The results of macroscopic, biochemical, bacteriological, and microscopic techniques of evaluating synovial fluid must be correlated to establish the diagnosis of each of the various forms of arthritis. The principle of polarized microscopy as applied to the differential diagnosis of crystalline arthritis is currently of special interest.

Adrenal Cortex Hormones↗