PubMed Health⌕ Search

Biomedical subjects

D W Brenner

Publications and source records attributed to D W Brenner.

10 recordsLinked to original sources
PubMed2006

STM, QCM, and the windshield wiper effect: a joint theoretical-experimental study of adsorbate mobility and lubrication at high sliding rates.

We have observed that when mobile adsorbed films of benzene, tricresyl phosphate, and tertiary-butyl phenyl phosphate are present on the surface electrode of a quartz crystal microbalance (QCM), oscillation of the QCM produces clearer scanning tunneling microscope (STM) images of the electrode surface. This is in contrast to an immobile overlayer of iodobenzene, where oscillation of the QCM does not affect image quality. This observation is attributed to a "windshield wiper effect", where at MHz frequencies the tip motion maintains a region of the surface where the absorbate concentration is reduced, which leads to a clearer image. A straightforward model is presented that supports this conclusion and that provides guidelines for effective lubrication of contacts operating at MHz frequencies.

Journal Article↗
PubMed1992

Suprarenal Greenfield filter placement to prevent pulmonary embolus in patients with vena caval tumor thrombi.

The presence of tumor thrombus secondary to inferior vena caval extension from renal carcinoma carries the threat of pulmonary tumor embolus. In theory, safe prophylaxis could be accomplished by placement of a Greenfield filter in the suprarenal vena cava, which has been accomplished without complication. We treated 6 patients with renal call carcinoma and extensive tumor thrombus of the vena cava with suprarenal filter placement as an adjunct to thrombectomy and nephrectomy. Clinically all 6 patients have done well. However, the over-all rate of vena caval thrombosis or occlusion associated with infrarenal filter placement is 3 to 5%. To investigate the potential risk to renal function if a vena caval occlusion occurred above a solitary kidney shortly after unilateral nephrectomy, we performed suprarenal inferior vena caval ligations after unilateral nephrectomy in 10 dogs. A total of 6 dogs suffered persistent loss of renal function and 3 of these 6 died of uremia. Of 4 dogs who underwent suprarenal inferior vena caval ligation only 1 (25%) had persistent compromise of renal function. A total of 2 dogs underwent unilateral nephrectomy only without compromise of normal renal function. We conclude that the risk of total vena caval occlusion after suprarenal Greenfield filter placement is small. However, should it occur in the setting of recent nephrectomy there is potential for significant renal morbidity. In selected patients this risk may be offset by the potential benefits that the filter offers in terms of protection against tumor and/or bland pulmonary embolus. Further clinical experience will be needed to strengthen and clarify the indications and benefits of preoperative or intraoperative filter placement as reported.

Adult↗
PubMed1990

Comparison of transrectal fine-needle aspiration cytology and core needle biopsy in diagnosis of prostate cancer.

One hundred sixty-nine transrectal fine-needle aspirations of the prostate gland were performed in 166 patients over a two-year period. The results were compared with simultaneous core needle biopsy performed in all but 4 patients. Forty-seven (28%) aspirations were either unsatisfactory or inconclusive. Of the remaining 122 (72%) patients in whom a cytologic diagnosis could be made, core biopsy was available in 120. Aspiration cytology was 87 percent sensitive and 96 percent specific with an overall agreement of 93 percent with core biopsy. No major complications occurred. We conclude that fine-needle aspiration of the prostate is accurate, safe, and cost-effective, and greater application of this technique is encouraged.

Biopsy, Needle↗
PubMed1989

Flow cytometric analysis of DNA content in children with neuroblastoma.

Flow cytometric DNA content analyses were performed in a retrospective study of archival tumor specimens of 15 patients with diagnosed neuroblastoma treated at a single institution. Survival statistics were positively influenced by the presence of aneuploidy. Kaplan-Meier analysis indicated a significant survival advantage for patients with aneuploid tumors (P = .036). Survivors were significantly younger at the time of diagnosis than nonsurvivors, but age at diagnosis did not correlate with DNA content. We conclude that DNA content analysis may be of value in determining the prognosis for children with neuroblastoma.

Adolescent↗
PubMed1987

Mortality associated with feeding catheter jejunostomy after radical cystectomy.

Twenty-five patients undergoing cystectomy and diversion for transitional cell carcinoma of the bladder and 8 patients having major surgery for renal and testes neoplasms and trauma have received needle jejunostomy placement at the time of surgery. One patient died secondary to vascular collapse. Postmortem examination revealed necrosis of the entire small bowel except the conduit segment. The implications of these findings are discussed.

Aged↗
PubMedDate not supplied

Adrenal pheochromocytoma presenting with persistent abdominal and flank pain.

Pheochromocytoma is classically associated with paroxysms of headache and hypertension. Its presentation, however, may be more varied and subtle. We present a case of an adolescent female who complained of right upper quadrant and flank pain. A right adrenal pheochromocytoma was diagnosed and subsequently removed. The pertinent literature is discussed.

Adolescent↗