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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↗
PubMed1989

AUR memorial award--1988. MRI enhancement of perfused tissues using chromium labeled red blood cells as an intravascular contrast agent.

It has been demonstrated that chromium (Cr) labeling significantly decreases the relaxation times of packed red blood cells (RBCs). In this study, the spin-lattice relaxation time (T1) of human red cells was shortened from 836 ms to 29 ms and the spin-spin relaxation time (T2) shortened from 134 ms to 18 ms, when the cells were labeled at a Cr incubation concentration of 50 mM. Labeling of canine cells at 50 mM resulted in a T1 of 36 ms and a T2 of 26 ms. A labeling concentration of 10 mM produced similar relaxation enhancement, with uptake of 47% of the available Cr, and was determined to be optimal. The enhancement of longitudinal and transverse relaxation rates (1/T1,-1/T2) per amount of hemoglobin-bound Cr are 6.9 s-1 mM-1 and 9.8 s-1 mM-1 respectively, different from those of a pure Cr+3 solution. Labeling cells at 10 mM decreased the survival half-time in vivo from 16.6 days to 4.7 days in dogs. No difference in red cell survival was found with the use of hetero-transfusion versus auto-transfusion of labeled RBCs. Significant shortening of the T1 (912 ms to 266 ms, P = .03) and T2 (90 ms to 70 ms, P = .006) of spleen and the T1 (764 ms to 282 ms, P = .005) and the T2 (128 ms to 86 ms, P = .005) of liver occurred when 10% of the RBC mass of dogs was exchanged with Cr labeled cells. Liver and spleen spin density changes (P greater than 0.23) and muscle spin density and relaxation changes (P greater than 0.4) were insignificant. The in vivo T1 of a canine spleen which had been infarcted did not change following transfusion with labeled cells, where the T1 of liver did shorten. We believe this preliminary study suggests that Cr labeled red cells may have the potential to become an intravascular magnetic resonance imaging contrast agent.

Animals↗
PubMed1989

Wrongful life and wrongful birth. Implications for diagnostic sonography.

We trust that this communication will further the understanding of the concepts involved in wrongful life and wrongful birth and will assist the conduct of medical practice in such a way to minimize risks to patients and ultrasound physicians with regard to their liability. When these physicians are involved in wrongful life cases, we believe that the concepts presented will assist them in understanding the legal and societal environment in which they find themselves. We hope also that this communication may assist the defense attorney to more effectively prepare a response to the plaintiff's legal theory. Knowledge should provide understanding, if not relief.

Expert Testimony↗
PubMed1988

Computed tomography and magnetic resonance imaging of the acute abdomen.

CT is a noninvasive investigation that in many instances is more sensitive in elucidating intra-abdominal and retroperitoneal disease than is conventional radiography. With modern scanners, the procedure is rapid and efficient and suitable for the most severely ill and infirm. The scans are easily interpretable, and the anatomic and morphologic depiction of disease is readily understood by those with surgical training. Information regarding the state of the bowel wall, mesentery, and intraperitoneal and retroperitoneal structures is displayed in greater detail than by any other diagnostic imaging modality. The use of intravenous contrast medium is rarely essential. The concentration of iodinated contrast needed for opacification of the bowel is no greater than 2 per cent to 5 per cent and will not complicate bowel surgery, as would standard upper gastrointestinal or barium enema studies. Abscess, free air, calcium, and intraperitoneal fluid are very sensitively detected. CT is extremely useful in aiding surgical decision making in the acute abdomen and is complementary to or has replaced conventional studies.

Abdomen, Acute↗
PubMed1988

Magnetic resonance imaging of ischemic bowel in rabbit model.

Acute mesenteric ischemic bowel disease is a common yet complex disorder with high morbidity and mortality rates predominantly caused by delayed diagnosis. We examined the role of magnetic resonance imaging (MRI) in the early detection of small bowel ischemia using the rabbit model. Surgical ligation of the appropriate arterial vascular supply to the ileum of 10 rabbits produced the ischemic compromise. The animals were imaged at different time intervals after the arterial occlusion. Multislice, T1 and T2-weighted images were obtained in axial and coronal planes. Abnormal findings of the dearterialized segment of bowel were visualized as early as 45 minutes after vascular occlusion. The findings consisted of: (1) bowel wall thickening, (2) two- to three-fold increase in signal intensity from bowel on T2-weighted images, and (3) isointensity or slightly increased signal intensity within the bowel wall on T1-weighted images. MRI appears to be a sensitive, noninvasive technique for the early detection of bowel ischemia in the rabbit animal model.

Animals↗