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Biomedical subjects

D Adams

Publications and source records attributed to D Adams.

At least 199 records · Page 11Linked to original sources
PubMed1987

In vitro color flow, pulsed and continuous wave Doppler ultrasound masking of flow by prosthetic valves.

On the hypothesis that Doppler ultrasound fails to penetrate prosthetic valves, an in vitro flow simulation system was constructed in a large water tank. Conventional pulsed, continuous wave and Doppler color flow systems were used to detect flow in tubing placed diagonally within the water and maintained by a continuous pump. After control periods of flow detection within the tubing, six different prosthetic valves were interposed on a stage between the transducer and the tubing. In comparison with control measurements, detection of flow within the tubing was impossible when the Doppler beam traversed the central occluding ball of the Starr-Edwards Silastic prosthesis by any modality. Marked reduction in the detection of the Doppler signal was noted for the Starr-Edwards stellite prosthesis with only slight improvement in the ability to detect the flow signals through the central occluding discs of the Björk-Shiley, Hall-Kastor and St. Jude valves. In distinction to the other valves, the ability of Doppler ultrasound to detect flow behind the cusps of the Carpentier-Edwards heterograft was similar to that during the control period. An understanding of flow masking should improve the clinical utility of Doppler methods for investigating prosthetic valve dysfunction.

Color↗
PubMed1987

Antimicrobial properties of 2 aliphatic amines and chlorhexidine in vitro and in saliva.

The surfactants tetradecylamine, hexadecylamine and chlorhexidine have been compared with regard to their ability to inhibit microbial growth. Antibacterial activity was assessed by tube dilution methods. Tetradecylamine and chlorhexidine were similar in antibacterial activity, being effective at low concentrations against most organisms tested. Hexadecylamine also inhibited growth but at higher concentrations. Viable counts of salivary organisms were monitored in volunteers over 48 h after one rinse with the agents. The initial reduction in numbers of total viable salivary bacteria and streptococci by tetradecylamine and of streptococci by hexadecylamine had disappeared 3 h after a single mouth rinse, but the reduction in numbers of all salivary bacteria by chlorhexidine was more prolonged.

Adult↗
PubMed1987

Dentine hypersensitivity. The effects in vitro of acids and dietary substances on root-planed and burred dentine.

Evidence indicates that teeth exhibiting cervical dentine hypersensitivity have open dentinal tubules at the dentine surface. The identification of factors which render dentine exposed and tubules open is important both to the prevention and management of dentine hypersensitivity. In this study, recently extracted teeth were root planed or burred to expose the root dentine. Specimens were horizontally sectioned and then using the apical portion as control, the coronal portions placed in a variety of strong and weak acids and dietary fluids. Examination under the scanning electron microscope revealed a smear layer covering completely underlying tubules on the control root planed or burred portions. Test portions exposed to strong and weak acids showed loss of the smear layer and exposure of large numbers of tubules. Formic and tannic acids produced no changes. Some dietary fluids, in particular red and white wine, citrus fruit juices, apple juice and yogurt produced similar etching effects to the acids. The low pH carbonated drink, coca-cola, and a blackcurrent cordial produced no effects. The results of this study in vitro cannot necessarily be extrapolated to the clinical situation, but suggest that certain dietary factors could play a rôle in the aetiology of dentine hypersensitivity. Dietary advice to patients may prove important in the management of this often recurrent condition.

Acids↗
PubMed1987

Dentine hypersensitivity. A study of the patency of dentinal tubules in sensitive and non-sensitive cervical dentine.

Based on the hydrodynamic theory for stimulus transmission across dentine, it would be logical to conclude that teeth exhibiting the clinical symptoms referred to as dentine hypersensitivity should have dentinal tubules open at the root surface and patent to the pulp. With the exception of studies on cut dentine, there is little direct evidence to support this conclusion. In this study, caries-free teeth with exposed cervical root areas scheduled for extraction which were classified as non-sensitive or hypersensitive after suitable stimulation were examined by scanning electron microscopy. Hypersensitive teeth showed highly significantly increased numbers of tubules per unit area (approximately 8 X) compared with non-sensitive teeth. Tubule diameters were significantly wider (approximately 2 X) in hypersensitive compared to non-sensitive teeth. The number of teeth showing the penetration of methylene blue through the zone of exposed cervical dentine was larger and the depth of penetration greater in hypersensitive teeth compared to non-sensitive teeth. The results provide further evidence that stimulus transmission across dentine in hypersensitive teeth is mediated by a hydrodynamic mechanism. An understanding of factors which open dentinal tubules would seem important if attempts to prevent or treat dentine hypersensitivity are to be successful.

Dentin↗
PubMed1986

The role of anger in the consciousness development of peace activists: where physiology and history intersect.

The focus of this paper concerns the role of anger in the development of consciousness in peace activists. By looking at this from 3 perspectives we can see an intersection of physiology and history. Looked at most closely, anger is a physiological event that recurs in the life of an individual. From a broader perspective, anger plays a critical role and a particular step in the development of consciousness. And from the broadest perspective, we may see how individual peace activists play a role in history by helping to resolve those contradictions (such as the present one between war and peace) by which history jerks its way forward. To put the proposition most carefully, it will be argued that anger is the personal fuel in the social motor that resolves the institutional contradictions that arise in the course of history. The materials on which this paper is based come from two sources. First is the study I have conducted in recent years on the development of consciousness in peace activists. Wishing to contribute my scientific skills to the peace movement, I have analyzed autobiographies of famous peace activists and oral histories of contemporary activists in Connecticut where I live. Since results from both the autobiographies and the oral histories are similar for present purposes, I will not make any distinction between them. The second source of material is the work that I and other researchers have conducted for many years on the brain mechanisms, behavioral complexities and evolutionary trends of aggressive behavior in rats, cats and monkeys. This material has been extensively published and is referred to in the bibliography (Adams, 1979, 1980).

Aggression↗
PubMed1986

Thyroid-stimulating autoantibodies usually contain only lambda-light chains: evidence for the "forbidden clone" theory.

Burnet's "forbidden clone" theory would predict that in patients with Graves' disease the pathogenic thyroid-stimulating autoantibody (TSab)-secreting clones arise by somatic mutation. Because each lymphocyte and its progeny are permanently committed to producing antibodies of a single light chain type, a clone arising by somatic mutation occurring in a single cell would be expected to produce autoantibodies of exclusively kappa or exclusively lambda type in an individual patient. Using affinity chromatographic techniques and monoclonal antibodies, we investigated the light chain type of TSab in 11 patients with Graves' disease. In all patients tested, TSab activity was confined to a single light chain type, confirming the recent work of Zakarija who used affinity chromatography with polyclonal antisera, but contrasting with earlier studies which used immuno-precipitation methods. Furthermore, the light chain type was lambda in 10 of the 11 patients. These observations provide support for the forbidden clone theory. In addition, the marked preponderance of patients producing TSab of the lambda-light chain type indicates that TSab are more likely to arise from the lambda repertoire of clones than from the kappa repertoire and suggests that immunoglobulin light chain V genes may be genetic determinants for susceptibility to Graves' disease.

Antibodies, Monoclonal↗
PubMed1985

Long-term visual acuity results after penetrating and perforating ocular injuries.

Of 33 consecutive patients (30 males and three females, ranging in age from 5 to 48 years) with penetrating ocular injuries, 13 had retained metallic intraocular foreign bodies. The remaining 20 had no retained foreign bodies and their injuries were generally more severe lacerating or double perforating injuries. Magnet extraction was used for foreign body extraction when possible, and pars plana posterior vitrectomy was used only for late complications. The long-term visual acuity results indicated that wound repair, conventional magnet extraction, and removal of traumatic cataract and anterior vitreous blood through a limbal incision is still a viable treatment for many such injuries.

Adolescent↗
PubMed1985

A reconsideration of Doppler assessed gradients in suspected aortic stenosis.

To further define the clinical role of continuous wave Doppler echocardiography for determining aortic valve gradient, we studied 60 consecutive adult patients (age range 22 to 81 years, mean age 63) with suspected aortic stenosis within 24 hours of catheterization. Blind comparisons of Doppler peak and mean gradients by the simplified Bernoulli equation were made with catheterization peak-to-peak (r = 0.84), peak (r = 0.87) and mean (r = 0.84) gradients in a double-blind fashion. Despite these favorable correlations, Doppler peak gradient generally overestimated catheterization peak-to-peak gradient (1 to 53 mm Hg), making it impractical for clinical use. Doppler-catheterization correlations of peak and mean gradients were more favorable, with the least scatter noticed for mean gradient. The results of analysis of pooled data indicated that mean gradient may also be most specific for differentiating severe from less severe aortic stenosis. In this consecutive series where a full range of catheterization gradients was encountered, seven patients with predicted Doppler gradients were found to have none, which is best explained by the use of the simplified Bernoulli equation in patients with aortic insufficiency. These data indicate that prudence should be maintained when Doppler gradients alone are used for the assessment of aortic stenosis.

Adult↗
PubMed1985

Dicesium N-succinimidyl 3-(undecahydro-closo-dodecaboranyldithio)propionate, a novel heterobifunctional boronating agent.

The synthesis of a novel heterobifunctional agent, dicesium N-succinimidyl 3-(undecahydro-closo-dodecaboranyldithio)propionate, is described. This structure contains an active ester component known to react rapidly under very mild conditions with amino groups of proteins, resulting in covalent linkage. With use of this boronating agent, approximately 480 boron atoms have been incorporated per molecule of a polyclonal antibody directed against human thymocytes and 1300 boron atoms per molecule were incorporated into a monoclonal antibody, 17-1A, directed against human colorectal carcinoma cells. Binding of the boronated antibodies to the corresponding target cells was demonstrated by means of membrane immunofluorescence. There was some loss in reactivity, as determined by fluorescent end point titers, but specificity remained unchanged. The data suggest that boronated antibodies potentially could be used to selectively deliver boron-10 to tumor cells in order to achieve their destruction by neutron capture.

Antibodies↗
PubMed1985

Direct measurement of local pressures in the cadaveric human hip joint during simulated level walking.

Eleven piezoelectric pressure transducers, each supporting an area of articular cartilage about 3 mm in diameter, were inserted through the bone of the acetabulum. Nine cadaveric hip joints, thus instrumented, were subjected to forces representing six instants in a typical level walking cycle, including the highest and lowest force. Under the highest force, the maximum pressure measured ranged from 4.93 to 9.57 MN m-2. The transducer positions which were subjected to the highest pressures were subjected at some other instant in the cycle to pressures which were an order of magnitude lower, or to zero pressure.

Adult↗