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Biomedical subjects

S Vaughan

Publications and source records attributed to S Vaughan.

36 records · Page 2Linked to original sources
PubMed1986

Occult gastric cancer manifested by progressive shortness of breath in a young adult.

We have reported a case of occult, diffuse gastric cancer in a young adult with progressive shortness of breath and bilateral pulmonary interstitial infiltrates. Progressive shortness of breath may be the first or only manifestation of occult gastric cancer caused by either lymphangitic carcinomatosis or microscopic tumor emboli to the lungs. Widespread recognition of this syndrome, a high index of suspicion, and prompt lung biopsy are necessary to make the correct diagnosis. With progress in chemotherapy for malignant diseases, early diagnosis and specific treatment may improve the prognosis of this condition.

Adenocarcinoma, Mucinous↗
PubMed1986

Intramucosal gastric carcinoma in a patient with familial polyposis coli.

Upper gastrointestinal polyps commonly occur in patients with familial polyposis coli; but the occurrence of gastric carcinoma is very rare in this disorder. We report a case of intramucosal gastric carcinoma in a patient with familial polyposis coli and multiple gastrointestinal adenomatous polyps.

Adenocarcinoma↗
PubMed1985

'O'-antigens are essential virulence factors of Shigella sonnei and Shigella dysenteriae 1.

A novel transposon mutagenesis system has been developed for Shigella. We have used it to isolate specific mutants of Shigella sonnei and Shigella dysenteriae 1 that fail to produce lipopolysaccharide 'O' side chains. The virulence of the mutants was evaluated in the Sereny test and in a HeLa cell invasion assay. All HO'-minus mutants failed to provoke a positive Sereny reaction but retained the ability to invade HeLa cells. This demonstrates that 'O' side chains are virulence factors of S. sonnei and S. dysenteriae 1. 'O'-minus mutants of S. sonnei which still contained the Form I plasmid were capable of invading HeLa cells whilst plasmid-minus mutants were not, demonstrating that this plasmid encodes properties other than 'O'-antigen production that are involved in virulence.

Antigens, Bacterial↗
PubMed1985

De novo carcinoma of the rectum: a case report.

There is strong evidence in the literature to suggest that most of the colorectal carcinomas arise from adenomatous polyps. Yet, rare carcinomas may arise de novo and we are reporting such a case of intramucosal rectal carcinoma occurring in a 47-year-old healthy man.

Adenocarcinoma↗
PubMed1984

Invasive ability of Plesiomonas shigelloides.

Five of 16 strains of Plesiomonas shigelloides freshly isolated from children with acute diarrhoea, exhibited invasiveness for HeLa cells comparable to that of Shigella sonnei. None of the five, however, gave a positive reaction in the Sereny test. Although three of the invasive strains shared antigens with Shigella, no correlation was observed between invasiveness and the possession of such antigens. Only one of the invasive strains produced a toxin detectable as causing rounding of HeLa cells, although others released a product which inhibited protein synthesis in HeLa cells but which failed to provoke any dramatic morphological change.

Bacterial Toxins↗
PubMed1982

Theoretical and experimental analysis of the single-coil pulsed-NMR method for measuring fluid flow.

A theoretical and experimental analysis of the application of pulsed proton nuclear magnetic resonance (NMR) to the measurement of fluid flow has been made. Calculations of the detector signal line shapes, S(t), for a single-coil NMR laboratory experiment, were performed using a computer to identify the optimum choice of flow signature. The theoretical model included the influence of coil-field shape, coil length, and effects of flow phase. High flow rates, typical of arterial blood flow, were simulated. Good correlation between theory and experiment was observed. The maximum amplitude of the slope of the signal [dS(t)/dt] was found to be the optimum flow signature. The line shape S(t) was found to depend on flow phase. Comparison between theory and experiment provided a better understanding of the potential of NMR for measuring fluid or blood flow.

Blood Flow Velocity↗
PubMed1974

Primary neuropathic amyloidosis in three brothers.

Neuropathic primary amyloidosis has not been previously described in an English family. We present the clinical and pathological findings in three brothers with this condition and suggest that they have suffered from that form of the disease described originally by Andrade.

Aged↗
PubMedDate not supplied

AIDS beliefs in young women: are they related to AIDS risk-reduction behavior?

Little is known about the relationship between AIDS beliefs and AIDS risk-reduction behavior, especially in young heterosexual adults. This study explores young women's beliefs and behavior regarding AIDS. The results of this exploratory study indicate that college women generally see AIDS as serious, do not see themselves as susceptible, and are uncertain if AIDS beliefs influence their contraceptive behavior. Higher susceptibility scores are consistently correlated with AIDS risk-reduction behavior, and women who believe that AIDS affects their contraceptive use are more likely to use condoms. Implications for practice and strategies to increase susceptibility in women at risk are discussed.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Theoretical analysis of the two-coil method for measuring fluid flow using nuclear magnetic resonance.

A theoretical study of the application of pulsed nuclear magnetic resonance (NMR) to the measurement of fluid flow has been made. Calculations of detector signal line shapes, for a two-coil NMR laboratory experiment, were performed using a computer to determine the appropriate choice of flow signature. Results of calculations are presented showing the sensitivity of the method to various experimental parameters. The position of the received peak signal, in time, was found to correlate directly with mean flow velocity. However, the shape of the received signal was observed to depend markedly upon the state of flow, i.e., laminar, turbulent (plug). Hence, accurate determinations of flow required a knowledge of flow type. The theoretical calculations provided a better understanding of the potential of NMR for measuring fluid or blood flow.

Blood Flow Velocity↗
PubMedDate not supplied

Development of an efficient electrohydraulic total artificial heart.

The efficient use of space and energy is achieved in a new implantable total artificial heart (TAH). To fit the orthotopic thoracic space, toroidal blood pumps encircle an energy converter, consisting of a centrifugal hydraulic fluid pump and a rotary reversing valve. The new centrifugal pump produces cardiac outputs of 6 L/min, with an average hydraulic efficiency of 47%. Toroidal blood pumps encircling the pump deliver a 60 cc stroke with an 85% ejection fraction and have a predictable blood flow pattern with no stagnant regions. Components have been characterized in vitro, and blood contacting elements have been tested in vivo.

Blood Flow Velocity↗
PubMedDate not supplied

A compact and noise free electrohydraulic total artificial heart.

The ABIOMED total artificial heart (TAH) is designed for long-term tether-free use in patients with end-stage heart disease. Blood pumping is achieved through hydraulic fluid motion across flexing diaphragms. The hydraulic power is derived from a miniature centrifugal pump (50% efficiency). Flow directional change needed for alternate left and right filling and ejection is achieved with a rotary valve. With no mechanical contact with the flexing membrane, the wedge angle between the two pumps sandwiching the energy convertor can be easily optimized for anatomic fit. The blood pumps (80 ml strokes) are fitted with trileaflet polyetherurethane valves (24 mm). The TAH is implanted using twist-lock stepless quick connectors to the inflow cuffs and outflow grafts. Left-right flow balance is achieved with an atrial hydraulic shunt placed between the left cuff and inflow valve. Animal studies show that the TAH fits very well in Long Horn calves weighing 90 to 100 kg and can provide cardiac output in excess of 10 L/min. A cadaver (85 kg) study showed the TAH fits within the pericardial region.

Adult↗
PubMedDate not supplied

Silicone absorption of elastomeric closures--an accelerated study.

There is a trend in the parenteral industry to move from the use of elastomeric closures which are washed, siliconized, dried and sterilized in-house at the pharmaceutical manufacturers' site to pre-prepared closures purchased from the closure supplier. This preparation can consist of washing to reduce particle-load and bioburden, siliconization, placement in ready-to-sterilize bags and may eventually extend to sterilization by steam autoclave or gamma irradiation. Since silicone oil lubrication is critical to the processability/machinability of closures, research was designed to investigate this phenomenon in closures prepared using the Westar RS (Ready-to-Sterilize) process. This paper presents the data gathered in a study of the characteristic of silicone absorption into elastomeric closures under accelerated conditions. Variables such as silicone viscosity, rubber formulation, effect of sterilization and others are considered.

Absorption↗