Biomedical subjects
Publications and source records attributed to G Joyce.
Melting of a monolayer plasma crystal in a radio-frequency discharge with no particles suspended above or below is studied. The experimental data are compared with results of molecular dynamics simulations and theory. It is shown that the melting is caused by the resonance coupling between the longitudinal and the transverse dust-lattice wave modes, due to the interaction of particles with the plasma wakes.
Collisions have traditionally been neglected in calculating the shielding around a small spherical collector in a plasma, and the plasma flow to the collector. We show analytically that, in dusty plasmas under typical discharge conditions, ion charge-exchange collisions lead to the buildup of negative-energy trapped ions which dominate the shielding cloud in the nonlinear region near a dust grain and substantially increase the ion current to the grain, even when the mean-free path is much greater than the Debye length.
BACKGROUND: The introduction of expensive but very effective antiviral medications has led to questions about the effects on the total use of resources for the care of patients with human immunodeficiency virus (HIV) infection. We examined expenditures for the care of HIV-infected patients since the introduction of highly active antiretroviral therapy. METHODS: We interviewed a random sample of 2864 patients who were representative of all American adults receiving care for HIV infection in early 1996, and followed them for up to 36 months. We estimated the average expenditure per patient per month on the basis of self-reported information about care received. RESULTS: The mean expenditure was $1,792 per patient per month at base line, but it declined to $1,359 for survivors in 1997, since the increases in pharmaceutical expenditures were smaller than the reductions in hospital costs. Use of highly active antiretroviral therapy was independently associated with a reduction in expenditures. After adjustments for the interview date, clinical status, and deaths, the estimated annual expenditure declined from $20,300 per patient in 1996 to $18,300 in 1998. Expenditures among subgroups of patients varied by a factor of as much as three. Pharmaceutical costs were lowest and hospital costs highest among underserved groups, including blacks, women, and patients without private insurance. CONCLUSIONS: The total cost of care for adults with HIV infection has declined since the introduction of highly active antiretroviral therapy. Expenditures have increased for medications but have declined for other services. However, there are large variations in expenditures across subgroups of patients.
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Seven patients with renal cell carcinoma involving the inferior vena cava underwent surgical resection between 1975 and 1991. Pre-operative staging defined five patients with stage T3bNoMo disease, one patient with stage T3bN1Mo, and one patient with stage T3bNoM1 disease. At operation one patient had tumour thrombus filling the right atrium. Two patients had tumour thrombus within the intrahepatic vena cava and four infrahepatic tumour thrombus. The mean follow-up is 34.4 months (median 40 months). Four patients have been followed for over 4 years. Three of these patients are survivors, two have remained disease-free since their initial surgery. The other patient had a liver resection at 49 months for a solitary metastases; he is currently disease free. One patient died at 38 months from a gastrointestinal haemorrhage. Three patients are 12 months or less postoperation. Operative mortality was zero. The mean postoperative hospital stay was 14.7 days. Data suggests that 3-10% of renal cell carcinomas will involve the inferior vena cava. The small number of patients in this series suggests that many patients with renal cell carcinoma involving the inferior vena cava are not referred for surgical assessment. These patients are potential surgical candidates. Their survival after surgical resection, excluding the group with extension of tumour thrombus into the hepatic cava or above, is not reduced when compared with other patients with renal carcinoma.
Thirty-six radical prostatectomies were performed over an 8-year period; 25 suitable patients (70%) presented with symptoms of bladder outflow obstruction. In 15 cases (44%), initial digital rectal examination was not indicative of malignancy. The primary tumour was understaged pre-operatively in 17 patients (48%). In 14 cases (41%) the pre-operative biopsy grade was different from the grade assigned to the tumour following radical prostatectomy. Radical prostatectomy is being performed with increasing frequency: trends in morbidity have been identified.
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Insertion of a ureteric stent is a common procedure in urologic practice. Ureteric stenting may be performed for: ureteric obstruction, benign or malignant: to prevent ureteric obstruction from stone fragments after extracorporeal shockwave lithotripsy (ESWL); or to prevent leakage from the upper urinary tract. A case of spontaneous knotting of a ureteric stent in situ is reported. Although this complication has been reported previously it is rare.
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Video endoscopy is the latest technical advance in the observation of the gastrointestinal tract. In 2 years, three video endoscope systems have emerged to develop the field of digital imaging. In order to accurately assess the rapidly changing technology, these state of the art systems were "bench" tested in an electronics laboratory to objectively compare resolution, brightness (luminosity), color intensity (chroma), and field of view. All systems were excellent, surpassing the professional broadcasting minimum standards for the adequate discrimination of objects and colors. The Welch Allyn Video-Endoscope originated video endoscopy continued to demonstrate a superior resolution; however this was at the expense of a significantly more narrow field of view, relative to the two newer systems. Although all systems have adequate luminosity and chroma, there were differences in the maximum amounts of luminosity and chroma. This is reflected in the observation that the most recently introduced system, Olympus Endoscopic Video Information System had relatively low levels of light beyond 9 cm from the tip, while the other systems had ample illumination. This report on the relative advantages of each system is based on the interpretations, implications, and practical applications of these findings.
By observing the effect of 0.08 and 0.02 mg/ml linoleic acid (LA on the electrophoretic mobility of fresh red blood cells derived from the parents of a subject with DMD, it has been shown that all of 16 fathers as well as 15 mothers, consistently differ from normal. In normal subjects, whilst 0.08 mg/ml LA causes increased mobility, 0.02 mg/ml causes reduced mobility (P less than 0.001). In both parents this reversal is abolished and 0.02 mg/ml LA gives the same increased electrophoretic mobility of the RBC as does 0.08 mg/ml. This indicates that there is qualitative alteration of the RBC membrane in both, apparently genetically determined. Only when such an abnormal male mates with an abnormal female can DMD occur in a male offspring; other children appear either normal or showing the same abnormality as do the parents, thus continuing the production of DMD parents, the chance mating of whom produces further DMD. The evidence supports the hypothesis that in DMD there is a widespread membrane disturbance. Other relatives have also been explored. It would appear that the common DMD of children is of autosomal recessive origin with strong limitation to the male.
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A labile factor in plasma (but not serum) of MS subjects confers MS like properties vis à vis effect of linoleic acid (LA) and arachidonic acid (AA), on the electrophoretic mobility of washed red blood cells (RBC) irrespective of their provenance. Plasma from anomalous MS relatives and other neurological diseases (OND) likewise confer corresponding properties on washed RBC. The magnitude of results produced by LA and AA on plasma coated cells is equal to that produced by LA and AA directly on the original cells and approximately twice that reported with latex particles.