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Biomedical subjects

B Williamson

Publications and source records attributed to B Williamson.

At least 91 records · Page 5Linked to original sources
PubMed1988

Intravenous urographic technique.

In these times of rapid advances in radiographic imaging, intravenous urography should be performed in an optimal way. The urographic examination should involve consultation between the referring physician and the radiologist. Necessary patient information should be accessible. McClennan said "patient selection for urographic studies should be efficacious with the radiologist exerting appropriate control so that the urogram is truly a consultative imaging service integrated into the total patient management." We share this view, and it is an extension of the philosophy of practice emphasized by other leaders in uroradiology. Cost containment, new imaging technologies, risk/benefit considerations, and evolving patterns of patient care have had a significant influence on genitourinary tract imaging. In addition, current debate about contrast media, digital radiography, efficacy, and utilization will undoubtedly have an influence on imaging during the next decade. Utilization of intravenous urography has decreased significantly in the past 15 years. Our volume of examinations has declined approximately 50% since 1970. This decline in our practice is attributed to several complex factors such as previous overutilization of screening urography for hypertension; the impact of US and CT for evaluation of obstruction, retroperitoneal disease (adenopathy and fibrosis), renal failure, and renal masses; concern about contrast medium-induced renal failure; and fewer repeat studies because of improved quality of intravenous urography in general radiology practice. In addition, overutilization of urography in patients with hematuria, prostatism, history of urinary tract infection, etc, continues to be debated in the medical community. In our integrated group practice, we have also observed overutilization of "high-tech" procedures in lieu of urography for evaluation of suspected urinary tract disease. Swings of the pendulum are inevitable in diagnostic imaging because of evolving technology and the art of medical practice. Although some differences of opinion about the details of urographic technique and indications for urography may exist, most would agree on the philosophy of producing a high-quality urographic examination. That philosophy focuses on producing the highest quality examination in each patient so that a diagnosis of normal or abnormal can be made accurately and confidently. Failure to demonstrate the entire urinary tract is a common cause of diagnostic error and one that can largely be eliminated by careful attention to the technical details of the examination.

Contrast Media↗
PubMed1986

Levels of plasticizer in the frequent plasma donor.

Di-2-ethylhexyl phthalate (DEHP), a commonly employed plasticizer reported to be carcinogenic in rats and mice, has been confirmed to leach from all plastic component parts of the equipment employed in plasma donation. Resident aqueous solutions of both sodium chloride and sodium citrate were found to contain only trace levels of DEHP (0.03 ppm), while stored plasma samples contained levels at least one order of magnitude higher (0.4 ppm). Since at least 5% of all plasma donations in the Los Angeles area are deemed to be of the high frequency classification, investigation into repeated red blood cell exposure to DEHP was considered imperative. However, there was no difference in the levels of DEHP found in the plasma of the frequent plasma donor (50-60 times per annum) relative to the first-time donor. It is concluded that there is no increased contamination threat to frequent plasma donation from migrating plasticizer via red blood cell exposure, at least during the collection process. Furthermore, there is no more risk to recipients of plasma products from frequent donors than from occasional donors. It would seem that the ambient level of DEHP to be expected in stored frozen plasma products averages no greater than about 0.5 ppm.

Blood Donors↗
PubMed1984

The isolation and characterization of cDNA clones for human apolipoprotein CII.

Recombinant clones containing cDNA sequences coding for human apolipoprotein CII have been isolated from a human adult liver cDNA library. The clones were detected by hybridization with a mixed probe consisting of 96 different oligonucleotides 17 bases long, complementary to the mRNA coding for amino acids 66 to 71 of apolipoprotein CII. The largest cDNA insert is 439 nucleotides long and contains the complete sequence for the mature protein, the 3' untranslated sequence, and sequence coding for 17 amino acids of a signal peptide. The cDNA clone was used to detect apolipoprotein CII mRNA approximately 500 bases long in human liver and intestine RNA.

Amino Acid Sequence↗
PubMed1984

Changing patterns in the evaluation of renal masses: economic implications.

This study compares the cost of evaluating renal masses at the Mayo Clinic before and after the use of sonography and computed tomography gained clinical acceptance. Two hundred two adult patients discovered to have renal masses in 1973 were compared with 204 patients discovered to have renal masses in 1980. After adjustment for inflation and differences in the frequency of the various diagnoses, the average cost of evaluating patients in 1980 was 30% less than the cost in 1973; this difference is statistically significant (p = 0.024). The reduction in cost is attributable primarily to a 77% decrease in the use of angiography. The largest reduction in cost occurred in the evaluation of malignant lesions. The study demonstrates that the clinical use of new imaging methods in the evaluation of renal masses can be associated with decreased costs for the patient.

Adenocarcinoma↗
PubMed1984

Cell cycle-specific effects of tumor necrosis factor.

The immediate effect of tumor necrosis factor (TNF) added to cultures of L-cells is cytostasis, manifested as cell arrest in G2. This effect prevails during the initial 4 hr when the number of G2 cells increases markedly in the absence of any significant cell death in the culture. Shortly thereafter, the cytolytic effect becomes apparent; extensive cell lysis can be detected after 7 hr of exposure to TNF. After 24 hr nearly all cells are lysed. Results of experiments in which the effects of TNF on the kinetics of cell progression through various phases of the cell cycle were studied indicate that in the presence of TNF cells do progress through G2, although with considerable delay, and reach mitosis. Most cells die (undergo lysis) specifically at late stages of mitosis (telophase) or soon after cytokinesis. Sensitivity of cells to the lytic effect of TNF is increased by cell arrest in mitosis with Colcemid or vinblastine. TNF exerts little effect on rates of cell progression through G1 or S phases of the cell cycle, although few cells die during S phase. Nonlysed cells from cultures treated with TNF do not show any changes in nuclear chromatin, suggesting that neither DNA nor nuclear proteins are the primary targets of the TNF. The present data implicate metabolic changes which occur during mitosis (cytokinesis), perhaps associated with synthesis or assembly of cell membrane components, as being responsible for increased cell sensitivity towards the cytolytic effect of TNF. The mechanism of the early cytostatic effect of the factor is unknown.

Animals↗
PubMed1983

Spectrum of sonographic findings in 125 renal masses other than benign simple cyst.

The sonographic findings of 125 renal masses that did not meet the sonographic criteria of benign simple cyst were retrospectively reviewed and correlated with the pathologic diagnosis. Of the 125 masses, 102 were renal cell carcinoma. These carcinomas, two of nine angiomyolipomas, and the 14 other renal masses of various histologic types exhibited a broad spectrum of sonographic findings. Seven of nine angiomyolipomas and the one multiloculated cystic nephroma had a rather characteristic sonographic appearance. With the knowledge of this spectrum of sonographic findings and strict attention to scanning techniques and sonographic criteria, the radiologist should be able to define the characteristics of a variety of renal masses and suggest the correct diagnosis. It should be possible to make the diagnosis of angiomyolipoma confidently if the characteristic sonographic and computed tomographic appearance of these tumors can be demonstrated. In some cases, the correct histologic diagnosis of a renal mass can be made only with biopsy or surgery.

Adenocarcinoma↗
PubMed1982

Gene therapy.

Gene therapy is not yet possible, but may become feasible soon, particularly for well understood gene defects. Although treatment of a patient raises no ethical problems once it can be done well, changing the genes of an early embryo is more difficult, controversial and unlikely to be required clinically.

Abortion, Induced↗
PubMed1982

Mortality during excretory urography: Mayo Clinic experience.

In a series of 300,000 consecutive patients who underwent excretory urography between January 1, 1964 and January 5, 1982, four deaths were recorded (a mortality rate of 1.3:100,000). All four patients who died were 50 years of age or older, all had a history of some type of hypersensitivity, all had a respiratory component to the reaction, all received a 1 ml test dose and had no reaction, and none had received a prior injection of contrast medium. The mortality rate in this series (1:75,000) is significantly lower than recently reported rates from multiinstitutional studies and is similar to the mortality rate resulting from the parenteral administration of penicillin. Differences in reported series may relate to methods of data collection, variations in patient population, and therapeutic management.

Aged↗