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Biomedical subjects

R Gould

Publications and source records attributed to R Gould.

53 records · Page 3Linked to original sources
PubMed1984

Beam attenuation devices for digital subtraction angiography.

A set of three contoured and beveled aluminum filters was constructed for routine use in a variety of digital subtraction angiography (DSA) applications. These adjustable devices are designed to compensate for the uneven x-ray penetration that occurs in many radiographic fields and may otherwise lead to video camera saturation, a major source of artifact in DSA. We have used this simple yet versatile adjunct in more than 200 DSA examinations with uniformly satisfactory results. Major advantages include elimination of the procedural delays that may be associated with more conventional approaches (such as the use of a bolus technique) and avoidance of misregistration artifact when pixel-shifting is used.

Angiography↗
PubMed1984

ECG-synchronized DSA exposure control: improved cervicothoracic image quality.

An electrocardiogram (ECG)-synchronized x-ray exposure sequence was used to acquire digital subtraction angiographic (DSA) images during 13 arterial injection studies of the aortic arch or carotid bifurcations. These "gated" images were compared with matched "ungated" DSA images acquired using the same technical factors, contrast material volume, and patient positioning. Subjective assessments by five experienced observers of edge definition, vessel conspicuousness, and overall diagnostic quality showed overall preference for one of the two acquisition methods in 69% of cases studied. Of these, the ECG-synchronized exposure series were rated superior in 76%. Linear intensity gradients across vessel margins generally showed improved or unchanged edge definition in the gated subtraction images as compared with their ungated pairs. These results, as well as the relatively simple and inexpensive modifications required, suggest that routine use of ECG exposure control can facilitate improved arterial DSA evaluations of suspected cervicothoracic vascular disease.

Adult↗
PubMed1983

Digital subtraction cerebral angiography by intraarterial injection: comparison with conventional angiography.

For 4 months, a prototype digital subtraction system was used to obtain images of the cerebral vasculature after intraarterial contrast injections. In 12 instances, the intraarterial injections were recorded with both a digital subtraction unit and conventional direct magnification film-screen system. The digital subtraction and conventional film subtraction images were compared and graded for quality and information content by three skilled observers. In addition, quantitative measurements of contrast-detail performance and spatial resolution were obtained on both the digital system and the screen-film imaging chain. In a clinical setting, both the digital subtraction and conventional film-screen systems provided similar quality images and angiographic information. Contrast-detail curves demonstrated that digital subtraction angiography outperformed conventional film technique for low-contrast objects. Digital subtraction angiography also reduced the time required to obtain the angiogram, markedly reduced film cost, and lowered the contrast agent burden.

Adolescent↗
PubMed1982

In vivo demonstration of small intestinal villi in dogs and monkeys using radiographic magnification.

Direct radiographic magnification (3.6 x) and a microfocal spot radiographic tube (0.13 mm) were used in double contrast studies of intestinal villi in adult dogs and monkeys. The villi appeared as lucent lines surrounded by barium in profile, and as lucent dots en face; this was verified by specimen radiographic and histological analysis. The use of fast screen-film combination, motility depressant, microfocal spot tube, and air-gap technique produced a radiograph of greater detail than that obtained with conventional focal spot, source-image distance, and film-screen combination. The advantages and limitations of microfocal direct magnification radiography of the small intestine are discussed.

Air↗
PubMed1982

Distribution of calcium-activated protease activity and endogenous substrates in the squid nervous system.

Calcium-activated protease (CAP) activity was studied in various neural tissues of the squid using endogenous (neurofilament protein) and exogenous ([14C]casein) substrate assays. Both assays demonstrated a significant CAP activity in perikarya from stellate ganglia, in axoplasm extruded from the giant axon, and in squid retinal fibers. The endogenous protein substrates in the perikarya and axons were 60,000 and 200,000 daltons, respectively. The Km for the CAP degradation of [14C] casein in axoplasm was about 2 x10-6 m. In contrast, both assays detected no CAP activity nor endogenous substrate in nerve terminals (synaptosomes from squid optic lobe). The absence of both CAP activity and endogenous substrate in nerve endings suggests that the axonal neurofilaments are degraded by CAP at the axon-nerve ending junction, followed by an autoinactivation of the CAP. Consistent with this hypothesis is that exposure of axoplasmic CAP to calcium leads to a rapid degradation of axonal neurofilament protein (t 1/2 less than 2 min) and a slower inactivation of the CAP (t 1/2 = 90 min). Axonal CAP requires a relatively high concentration of CA2+ sensitivity form of CAP found in other tissues.

Animals↗
PubMed1981

Symmetric sarcoid polyneuropathy: analysis of a sural nerve biopsy.

A 20-year-old woman with sarcoidosis had uveitis, subacute symmetric sensorimotor neuropathy, and noncaseous granulomas in biopsies of gastrocnemius muscle and sural nerve. Morphologic studies of the nerve confirmed the electrodiagnostic impression of an acute axonal and demyelinating neuropathy. Of 100 teased myelinated nerve fibers, 15% contained myelin ovoids and 24% demonstrated segmental demyelination. Quantitative analysis showed a reduction in the numerical density of myelinated fibers. By electronmicroscopy, unmyelinated fibers were largely spared. The exact mechanism of nerve fiber damage was not determined, but a local effect of the granuloma seemed likely, because most lesions were found in the endoneurium.

Adult↗
PubMed1978

Comparative sensitivity of CT scans, radiographs and radionuclide bone scans in detecting metastatic calvarial lesions.

CT scans of 100 patients with histologically diagnosed extracerebral neoplasms were reviewed and compared with either radionuclide bone images or skull radiographs. The results of this correlative study indicate that CT scans are more sensitive than skull radiographs in detecting corresponding calvarial lesions; conversely, radionuclide bone scans appear to be more sensitive than CT in detecting similar lesions.

Aged↗
PubMed1977

The effects of self-esteem and evaluator demandingness on effort expenditure.

The self-esteem of subjects was temporarily either raised or lowered by giving them false feedback on an alleged personality test. Subjects then participated in what they believed was a second, separate experiment in which they would engage in problem solving. Half the subjects in each self-esteem condition were led to believe that the evaluator of their problem-solving performance was difficult to please; the remainder, that he was easy to please. Subjects then committed themselves to expending effort in preparation for the problem-solving exercise. Based on a self-enhancement perspective derived from attributional principles, an interaction was predicted: High self-esteem subjects would plan to exert greater effort when the evaluator was demanding than when he was undemanding, whereas low self-esteem subjects would exert greater effort when the evaluator was undemanding. The results supported the hypothesis and are discussed with respect to consistency theory, as well as in the context of self-enhancement ideas.

Achievement↗
PubMedDate not supplied

Blood lead levels in Toronto children and abatement of lead-contaminated soil and house dust.

South Riverdale in Toronto, Canada, underwent a lead-abatement program. In 1988, lead-contaminated soil was replaced at 970 properties, and in 1989, professional housecleaning for lead removal was conducted in 717 households. The effect of "abatement" on blood lead levels in young children was investigated. Data were analyzed from 12 cross-sectional blood-screening surveys that were conducted during an 8-y period in South Riverdale and in two comparison areas. Responses regarding behavioral, household, lifestyle, neighborhood, and environmental factors, all of which were gleaned from associated questionnaires, were also analyzed. Response rates varied between 32% and 75%. During the years between 1984 and 1992, blood lead decreased in all study areas. There appeared to be a minimal blood lead level of 2-3 micrograms/dl for urban Ontario children who were less than 6 y of age. The significant difference between South Riverdale and the control areas disappeared by 1992. Although abatement activity in South Riverdale was associated with an accelerated decline in blood lead levels, it was difficult to distinguish this from effects of decreased Toronto air lead levels or decreased smelter emissions. Within South Riverdale, abatement appeared to be associated with a slower decline in blood lead levels over time, likely the result of selection bias, soil mixing, or recontamination from the smelter. No difference was observed between the separate effects of housecleaning or soil replacement. The findings could neither strongly support nor refute beneficial effects of abatement.

Analysis of Variance↗
PubMedDate not supplied

Loose body within the glenohumeral joint in recurrent anterior dislocation: CT demonstration.

A loose body within the glenohumeral joint in a patient with chronic anterior dislocation and recent trauma that prevented successful reduction of the dislocated shoulder was demonstrated by CT. Although the use of CT with arthrography has been reported in patients with recurrent dislocations and unstable shoulders, this is the first such reported demonstration using CT without contrast medium of a loose body preventing reduction.

Female↗