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Biomedical subjects

T R Miller

Publications and source records attributed to T R Miller.

At least 163 records · Page 9Linked to original sources
PubMed1989

Crash costs and safety investment.

Injury crashes cost society more than $34 billion annually. Expending up to $2.3 million to prevent one fatal crash appears to be rational public policy, although the crash costs society only $500,000. Prevention of severe, nonfatal head and spinal cord injuries warrants even larger expenditures. The estimated rational investment to prevent an average nonfatal injury crash is $22,000, while society's cost is $8,000. Rational investment levels for increased safety are estimated by summing the amount individuals typically pay for small increases in their safety and the cost the rest of society bears when someone is killed or injured, including transfer payments.

Accident Prevention↗
PubMed1989

Malignant versus nonmalignant retroperitoneal fibrosis: differentiation with MR imaging.

To evaluate the features on magnetic resonance (MR) images of malignant and nonmalignant retroperitoneal fibrosis (RPF) and to assess the usefulness of MR imaging in differentiating the two conditions, MR studies of nine patients with malignant RPF were retrospectively examined and compared with those of eight patients with nonmalignant RPF. Morphologic findings at MR imaging were similar for both conditions. The lesions were, however, heterogeneous in six of the nine patients with malignant RPF and homogeneous in all eight patients with nonmalignant RPF. On T2-predominant images, malignant RPF showed high signal intensity, while nonmalignant RPF showed low signal intensity. On T2-predominant images, signal intensity and T2 were significantly higher in malignant RPF than in nonmalignant RPF. Differentiation between malignant and nonmalignant RPF appears feasible and depends on tissue contrast rather than on morphologic characteristics.

Adult↗
PubMed1989

Three-dimensional display of gated cardiac blood-pool studies.

There has been little interest in use of single photon tomography in gated cardiac blood-pool imaging. This fact arises most likely from two principal causes: the difficulty associated with interpretation of images presented as series of beating slices, and the formidable computational burdens involved in processing the data. We have addressed both of these issues. A new method, called volume rendering, is used to generate realistic and easily interpreted three-dimensional images of the cardiac blood pool. These images of the beating heart can be displayed in a continuously rotating cine format or viewed in any orientation selected by the observer. Total computation time for a 16-frame gated study, including filtered backprojection, spatial and temporal filtering, and volume rendering, is 82.7 min employing a 32-bit computer and an array processor. With greater use of the array processor it should be possible to reduce the time to approximately 40 min, thus making routine use of these three-dimensional images clinically feasible.

Data Display↗
PubMed1989

Distinct requirements for activation at CCK-A and CCK-B/gastrin receptors: studies with a C-terminal hydrazide analogue of cholecystokinin tetrapeptide (30-33).

We describe here the properties of tert-butyloxycarbonyl-Trp-Leu-Asp-Phe-NHNH2 (A-57696), a C-terminal hydrazide analogue of tert-butyloxycarbonyl-CCK4 (Boc-Trp-Met-Asp-Phe-NH2), at four cholecystokinin (CCK) receptor-bearing tissues, the guinea pig pancreas and gall bladder (Type A), guinea pig cortex (Type B), and NCI-H345 cells, a human small cell lung cancer cell line that expresses CCK-B/gastrin receptors. Using 125I-Bolton-Hunter-cholecystokinin octapeptide (26-33) (125I-Bolton-Hunter-CCK8) as the radioligand, A-57696 was found to be selective for cortical CCK-B receptors (IC50 = 25 nM), compared with pancreatic CCK-A receptors (IC50 = 15 microM). A-57696 behaved as a competitive antagonist in reversing CCK8-stimulated pancreatic amylase secretion and phosphoinositide breakdown. By Schild analysis, its Kd was determined to be 4.7 and 6.8 microM in amylase and phosphoinositide assays, respectively. A-57696 (100 microM) did not elicit gall bladder contraction, and it inhibited contractions induced by CCK8. The Kd of A-57696 at gall bladder CCK-A receptors was 19 microM. In contrast, A-57696 behaved as a partial agonist (80% of maximal CCK8 response) in stimulating calcium mobilization at CCK-B/gastrin receptors on NCI-H345 cells. A-57696 and CCK8 inhibited each other in calcium mobilization experiments utilizing the fluorescent dye Indo-1. Stimulatory actions of CCK8 and A-57696 were reversed by the CCK-B-selective (R)-L-365,260 (100 nM), whereas at the same concentration, the CCK-A-selective (S)-L-365,260 was ineffective. Binding studies using 125I-Bolton-Hunter-CCK8 and 125I-gastrin indicated that binding sites labeled by these two ligands displayed similar affinities for CCK8, desulfated CCK8, gastrin, A-57696, and both enantiomers of L-365,260. A-57696 represents a new class of CCK-A peptide antagonist at guinea pig pancreas a new class of CCK-A peptide antagonist at guinea pig pancreas and gall bladder. Its contrasting functional activities at guinea pig CCK-A and CCK-B/gastrin receptors in a human tumor cell demonstrate that, in addition to the previously described differences in binding specificity for selective agonists and antagonists, CCK-A receptors and CCK-B/gastrin receptors have different requirements for activation.

Amino Acid Sequence↗
PubMed1989

The use of fine-needle aspiration biopsy in children.

Fine-needle aspiration biopsy has become increasingly popular for evaluating both palpable and nonpalpable masses. Judging from the current body of literature, this procedure is underused by American pediatricians. We report a series of 84 pediatric patients--younger than 16 years--who underwent 92 fine-needle aspiration biopsies to evaluate a large variety of masses. The results of 51 (55%) were benign, and 33 (36%) biopsies revealed malignancy. In two cases (2%) the findings were suggestive of malignancy, and in six cases (7%), insufficient material was rendered for diagnosis. Either histologic or clinical follow-up or both were available for 85 procedures. Based on these cases, the sensitivity of 97% and the specificity was 95%, indicating that fine-needle aspiration biopsy is a good method for screening and observing patients for various malignant tumors in a variety of organs.

Adolescent↗
PubMed1988

A step-wise logistic regression analysis of hepatocellular carcinoma. An aspiration biopsy study.

Fine needle aspiration biopsy (FNAB) has become a popular method to diagnose mass lesions of the liver. Although several reports have listed FNAB criteria to be used to diagnose both primary and metastatic tumors of the liver, none have separated key cytologic criteria from secondary criteria. We reviewed the FNAB smears from 35 patients with proven hepatocellular carcinoma and 74 patients with proven metastatic tumors in the liver. All specimens were coded as to the presence or absence of the following variables: polygonal cells with centrally placed nuclei; well-defined, granular cytoplasm; large nucleoli; small cytoplasmic vacuoles; large cytoplasmic vacuoles; bile; polymorphonuclear leukocytes; malignant cells separated by sinusoidal vessels; endothelial cells surrounding tumor cell clusters; multinucleated tumor giant cells; basophilic intracytoplasmic inclusions; eosinophilic intracytoplasmic inclusions; and intranuclear cytoplasmic inclusions. A step-wise logistic regression analysis was performed on the data to determine the variables predictive of hepatocellular carcinoma. The statistical analysis selected polygonal cells with centrally placed nuclei, malignant cells separated by sinusoidal capillaries, and bile as the key cytologic criteria for hepatocellular carcinoma. Endothelial cells surrounding tumor cell clusters and intranuclear cytoplasmic inclusions were selected as secondary criteria by this analysis.

Biopsy, Needle↗
PubMed1988

Image cytometric classification of premalignant breast disease in fine needle aspirates.

Image cytometry for the classification of fine needle aspirate (FNA) biopsies was evaluated in samples from 39 women. Eighteen of them had benign lesions, seven had premalignant lesions, nine had carcinoma in situ, and five had carcinoma. The term, premalignant, here refers to lesions with an increased risk of developing into breast cancer (atypical hyperplasia and, to a lesser extent, moderate or florid hyperplasia). The classifications by cytometry were compared with the microscopic diagnoses of the same FNA samples and of tissue from a subsequent surgical biopsy of the same area. One slide from each breast FNA sample was restained in Azure-A Feulgen. Breast epithelial cells were measured using a texture analysis program on the Leitz TAS-plus. The mean, standard deviation (SD), and interquartile range were calculated for each of 12 nuclear parameters from 200 cells per slide. A discriminant analysis was used to develop a statistical model for classifying individual samples. Six of seven atypical proliferative lesions (atypical hyperplasia and moderate hyperplasia) were identified by image cytometry, but were unrecognized by conventional microscopic examination.

Biopsy↗
PubMed1988

Cytologic criteria for fibroadenoma. A step-wise logistic regression analysis.

The authors reviewed the fine-needle aspiration biopsy smears from 62 subjects with proven fibroadenoma, 60 subjects with proven ductal carcinoma, and 42 subjects with proven fibrocystic disease. All smears were coded as to the presence or absence of the following variables: epithelial cells, stroma, honeycomb sheets, antler horn clusters, naked nuclei, nucleoli, marked cellularity, foam cells, apocrine cells, anisokaryosis, atypical nuclear hyperchromasia, single cells with cytoplasm, mitotic figures, and nuclei greater than two red blood cell diameters. Step-wise logistic regression analyses were performed to determine the variables predictive of fibroadenoma. The statistical analyses selected stroma, antler horn clusters, and marked cellularity as the key cytologic criteria to differentiate fibroadenomas from fibrocystic disease. The statistical analyses selected stroma, antler horn clusters, and honeycomb sheets as the key cytologic criteria to differentiate fibroadenoma from ductal carcinoma.

Adenofibroma↗
PubMed1988

Intraocular lymphoma: immunological and cytological analysis.

We retrospectively reviewed the cytology and immunohistology of vitreous specimens from nine patients with intraocular lymphoma (ocular reticulum cell sarcoma). A single vitreous biopsy specimen was not always adequate to establish the diagnosis in this condition. Cytological evaluation was more accurate than lymphocyte surface marker analysis to differentiate lymphoma from uveitis. The immunological features of these tumours indicate a heterogeneous group of intraocular lymphomas.

Adult↗
PubMed1988

Sternal blood flow after median sternotomy and mobilization of the internal mammary arteries.

Although the internal mammary artery (IMA) is superior to the saphenous vein graft for bypassing certain coronary arterial obstructive lesions, such operations may predispose the patient to sternal infection or dehiscence--presumably as a result of sternal ischemia. This study was designed to measure sternal blood flow before and after median sternotomy and IMA mobilization in order to quantify the hemodynamic effects of these procedures. Rhesus primates were randomized into control, unilateral IMA-harvested, and bilateral IMA-harvested groups. After selective angiography enabled confirmation of IMA patency, 15 micron microscopheres, labeled with specific-spectra radioactive isotopes, were injected at baseline, after sternotomy, and after IMA harvesting. The sternal halves were subjected to gamma counting, and sternal circulation was accurately quantified. Our results showed that blood flow to the sternal halves in which the IMA was harvested decreased precipitously (from 4.5 to 0.8 ml/gm/min; p less than or equal to 0.001), although it remained unchanged in response to median sternotomy. This represented a 90% decrease in the mean rate of flow within the IMA-harvested sterna versus a stable flow rate for the unharvested sides. We conclude that mobilization of the internal mammary artery, as in coronary bypass procedures, significantly devascularizes the sternal half from which it was harvested.

Animals↗
PubMed1988

Three-dimensional display of positron emission tomography of the heart.

A method for producing images of 82Rb myocardial perfusion and 11C carbon monoxide gated blood pool images is described. In the case of 82Rb images, cylindrical projection displaying myocardial activity as viewed from the side is presented to complement the polar projection. Cubic display of the conventional short- and long-axis slices is described that permits interactive selection of any desired slices. A three-dimensional cine display of the left ventricle rotating about its long axis is produced that gives a very realistic presentation of myocardial activity. Very similar processing techniques are applied to gated carbon-11 blood-pool studies to yield beating images of the surface of the blood pool in multiple projections.

Carbon Monoxide↗
PubMed1988

Stationary and nonstationary spatial domain Metz filtering.

Stationary and nonstationary finite-impulse-response (FIR) implementations of the count-dependent Metz filter were investigated in this study. Filter size was observed to be an important variable controlling image quality. For Metz filtering of 128 X 128 pixel images at least a 15 X 15 term FIR filter was deemed necessary. By using an algorithm which selected between a set of preformed FIR filters based on pixel count, a nonstationary FIR implementation of the Metz filter was developed which required very little increase in execution time to stationary filtering. In a limited comparison of 'tumor' detection with stationary and nonstationary FIR filtering all of the Metz filtering techniques showed a significant improvement in detection when compared to the unprocessed images. However, no significant difference was observed between the stationary and nonstationary Metz filtering techniques. Thus, for Metz filters optimized solely on the basis of count, nonstationary FIR filtering does not seem to offer an advantage when compared to stationary filtering.

Filtration↗
PubMed1987

Phacofragmentation and aspiration for cataract extraction in dogs: 56 cases (1980-1984).

Fifty-six cases of cataract removal in dogs by phacofragmentation and aspiration were reviewed. Improvement of vision was detected in the immediate postoperative period in 53 (94.6%) of 56 dogs. Vision was present in 25 (85.2%) of 29 dogs evaluated at 2 years after surgery, and in 5 (71.4%) of 7 dogs evaluated 4 years after surgery. Reasons for failure of visual improvement and complications in visual eyes were related primarily to development of postoperative anterior uveitis. Age of the dog at surgery was not a significant factor in the restoration of vision.

Animals↗
PubMed1987

An efficient and cost effective nuclear medicine image network.

An image network that is in use in a large nuclear medicine department is described. This network was designed to efficiently handle a large volume of clinical data at reasonable cost. Small, limited function computers are attached to each scintillation camera for data acquisition. The images are transferred by cable network or floppy disc to a large, powerful central computer for processing and display. Cost is minimized by use of small acquisition computers not equipped with expensive video display systems or elaborate analysis software. Thus, financial expenditure can be concentrated in a powerful central computer providing a centralized data base, rapid processing, and an efficient environment for program development. Clinical work is greatly facilitated because the physicians can process and display all studies without leaving the main reading area.

Computer Communication Networks↗
PubMed1987

Three year follow-up of benign fine-needle aspiration biopsies of the breast.

Benign fine-needle aspiration, taken in context, is a reasonable alternative to open biopsy. We found a false-negative rate comparable to that for frozen section or routine histologic examination of benign surgical breast biopsies. Fine-needle aspiration must always be interpreted in context. It is never satisfactory to use this test to ignore or choose not to surgically biopsy a lump that is suspicious on clinical grounds or on the basis of other tests.

Adult↗