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Biomedical subjects

A E James

Publications and source records attributed to A E James.

At least 19 recordsLinked to original sources
PubMed1991

The diffusion of medical technology: free enterprise and regulatory models in the USA.

The diffusion of technology in the US has taken place in an environment of both regulation and free enterprise. Each has been subject to manipulation by doctors and medical administrators that has fostered unprecedented ethical dilemmas and legal challenges. Understanding these developments and historical precedents may allow a more rational diffusion policy for medical technology in the future.

Certificate of Need↗
PubMed1990

Dermatomyositis: correlative MR imaging and P-31 MR spectroscopy for quantitative characterization of inflammatory disease.

Magnetic resonance (MR) imaging and phosphorus-31 MR spectroscopy were used to examine four patients with dermatomyositis and five control subjects. T2-weighted images of the thigh muscles of patients showed increased signal intensity, with focal and inhomogeneous involvement predominantly in the vastus lateralis and secondarily in the vastus intermedius and vastus medialis. T1 and T2 values of the vastus lateralis in patients were significantly higher than those of the control subjects. T1 values of the rectus femoris and biceps femoris with more generalized inflammation were moderately elevated but still significantly higher than those of the control subjects. P-31 MR spectra of the quadriceps muscles were obtained during rest, during exercise at two graded levels, and in recovery. Concentrations of adenosine triphosphate and phosphocreatine (PCr) in the diseased muscles were 30% below normal values, and the inorganic phosphate/PCr ratios were increased in the patients' muscles at rest and throughout exercise. The T1 and T2 values as well as the P-31 metabolite data correlated with symptoms and clinical assessment.

Adult↗
PubMed1990

Transvaginal sonography of postmenopausal ovaries with pathologic correlation.

The sonographic appearance of 67 ovaries in 34 postmenopausal women who underwent preoperative transvaginal sonography (TVS) was correlated to findings on pathologic examination. Both ovaries were detected by TVS in 60% of the women examined; in 85%, at least one ovary was detected. The size of the normal, sonographically visualized postmenopausal ovary was 2.2 +/- 0.7 cm in transverse, 1.2 +/- 0.3 cm in anteroposterior, and 1.1 +/- 0.6 cm in longitudinal axes, with an average volume of 2.6 +/- 2.0 cm3. The average size of ovaries that were not detected by TVS was 0.7 x 0.4 cm (range, 0.3 to 1.3 cm); most of these (five of six) were atrophic on pathologic exam. The difference between actual and sonographically measured size was negligible (TVS overestimated by 0.3 cm). Four simple cysts that ranged from 0.5 to 3.5 cm were found by TVS and confirmed pathologically, as were three benign serous cystadenomas that ranged from 2.5 to 3.5 cm, one 3 x 6-cm tubal carcinoma, and one 1 X 4-cm paratubal cyst. TVS missed a 6-cm dermoid, a 2.5-cm cystadenoma, a 0.8-cm Sertoli cell tumor, and a 0.5-cm fibrothecoma that were nonpalpable but that were found on pathologic examination. None of the missed lesions were palpable preoperatively. The positive predictive value was 94% for detection of an ovarian mass; the negative predictive value for exclusion of an ovarian lesion was 92%. It is concluded that TVS can accurately delineate the ovaries in most, but not all, postmenopausal women and that only rarely will pathologic lesions not be detected by TVS.

Aged↗
PubMed1986

Transrectal sonography of benign and malignant prostatic lesions.

Using linear-array transrectal prostate sonography, malignant lesions in 43 patients and benign lesions in 74 patients were evaluated. Prostate sonography was sensitive to textural changes produced by both benign and malignant diseases. However, there was considerable overlap in the sonographic appearances of benign and malignant lesions, and there were no sonographic features that reliably predicted malignancy. Hyperechoic areas were present in 58% of the carcinomas, while 19% were purely hypoechoic. Lesions containing hypoechoic foci that were posterior or posterolateral had a high incidence of cancer. The results confirm the need to biopsy all suspicious palpable lesions of the prostate.

Adenocarcinoma↗
PubMed1979

Antitrust law and the practice of radiology.

Physicians now find it relevant to acquaint themselves with aspects of the law which heretofore were mainly of concern to the business world. One such area is antitrust, which is beginning to affect the practice of radiology. Three phases of the problem are discussed: exclusive privileges contracts; boycotts of nonphysician consultations (i.e., with chiropractors and cultists); and certificate of need requirements for acquisition of highly technical, sophisticated and expensive equipment.

Certificate of Need↗
PubMed1979

Cellular attachment as a sensitive indicator of the effects of diagnostic ultrasound exposure on cultured human cells.

Dispersed cultured human cells (T-1 kidney, FL embryonic kidney, ES amniotic, and JHA amniotic) were seeded into plastic Petri dishes, incubated for 45 minutes, exposed to a clinical ultrasound source [total power output, 1.76 +/- 0.18 (S.D.) mW] for 0.25-60 minutes, and the medium replaced. Attachment was significantly reduced after only 0.50 minute of exposure. For all exposures, sensitivity of the JHA amniotic cells was greater than that of the kidney lines. Like incremental reduction in attachment, differential sensitivity among cell lines became less pronounced with protracted exposures. Thus cellular attachment is a sensitive parameter for studying the effects of diagnostic ultrasound.

Cell Adhesion↗
PubMed1979

Sonographic patterns of distended, fluid-filled bowel.

When small or large bowel is distended with fluid, certain characteristic features can be seen on ultrasound which cannot be visualized when the bowel is collapsed. The proximal and distal portions of the small bowel can frequently be differentiated both in vitro and in vivo by the echoes emanating from the valvulae conniventes ("keyboard sign"). This depends upon the angle at which the bowel segment is scanned in relation to its long axis, the relative amount of intraluminal fluid and gas, the diameter of the bowel in relation to the beam width of the transducer, and the intrinsic resolution of the scanning system. Similarly, the ascending and transverse colon can be recognized by haustral sacculations, the distal rectosigmoid colon and rectum by the rectal valves. The tubular shape, characteristic arrangement and location, and peristaltic motion of most fluid-filled bowel segments are helpful in differentiating loops of bowel from cystic masses in the abdomen or pelvis.

Colon↗
PubMed1979

Relation of age and cerebral ventricle size to central canal in man. Morphological analysis.

The central canal of the spinal cord in man with and without hydrocephalus was studied histologically. The lumen was patent in most patients in the first two decades of life. Cells lining the canal in the prenatal and newborn state and in the first decade of life were predominantly pseudostratified ciliated epithelium. In the second decade, the epithelium became simple columnar or cuboidal. The central canal closed in most cases after the age of 20 years, secondary to proliferation of ependymal cells and astrocytes. Mechanisms whereby the number of glial cells increase are considered. The canal was closed in all adults with normal ventricular size, and in 94% of persons with various degrees of hydrocephalus. In the remaining 6% of cases with hydrocephalus, the lining of the canal resembled that seen in the first two decades, and could have acted as a pathway of cerebrospinal fluid (CSF) absorption. Three cases of severe hydrocephalus in the first two decades of life were encountered; the central canal was patent in one, and occluded in two. Based on these data, the canal was not a significant pathway of CSF absorption in most instances of hydrocephalus and in persons with dilated ventricles who were older than 20 years of age.

Adolescent↗