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Biomedical subjects

N L Martin

Publications and source records attributed to N L Martin.

At least 55 records · Page 3Linked to original sources
PubMed1987

A digital radiology imaging system: description and clinical evaluation.

We have successfully interfaced an advanced microcomputer system to a 47-cm image intensifier for direct digital radiology. Our development effort has included the design and construction of hardware and the implementation of software. The system matrix (spatial resolution) is 1024 X 1024 and contrast resolution is 8 bits deep. A receiver-operator-characteristic analysis comparing conventional and digital laser chest radiographs for the detection of lung nodules demonstrated no statistical difference. Dosimetry measurements identified decreased patient dose. The intensifier-based digital imaging system is being increasingly used for a variety of examinations including IV pyelograms, all kinds of barium studies, and skeletal, trauma, and chest studies. Hard-copy laser-printed digital images with "bones black" are preferred by the radiology staff and have been well accepted by referring clinicians.

Evaluation Studies as Topic↗
PubMed1987

Fostering lambs by odor transfer: the add-on experiment.

Lamb-specific odor is used by ewes to discriminate between their own and alien offspring. Recent studies have demonstrated that fostering can be facilitated by transferring own-lamb odor to alien lambs via cloth stockinettes. The objective of the present study was to investigate the effectiveness of the odor-transfer technique in enticing ewes with a single lamb to adopt an additional lamb ("add-on" procedure). Shortly after birth, nylon stockinettes were placed on the single offspring of 49 ewes and 49 additional alien lambs designated for fostering. Approximately 20 h following parturition, stockinettes were removed from 41 natural lambs and placed on alien lambs (experimental treatment). In the control treatment (eight ewes) own and alien lambs retained their own stockinettes. Four acceptance tests were conducted, 24 h apart, starting at the onset of fostering. Successful adoptions were attained for 21 of 31 experimental ewes (68%) exposed to add-on lambs similar in facial coloration to their own lambs. Only 2 of 10 experimental ewes (20%) with whiteface natural lambs adopted blackface add-on lambs. One of eight control ewes (12.5%) adopted an add-on lamb. Of the 24 ewes that adopted alien lambs 10 (41.7%) demonstrated immediate acceptance and 20 (83.3%) had adopted lambs by the second test day. A higher proportion of primiparous than multiparous ewes adopted alien lambs. The presence of own-lamb odor on stockinettes worn by add-on lambs appears to facilitate fostering. However, the presence of own-lamb odor may not be a significant-enough cue to override obvious differences in facial coloration between own and add-on lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Gentamicin interaction with Pseudomonas aeruginosa cell envelope.

Gentamicin, an aminoglycoside antibiotic known to inhibit protein synthesis, had a detrimental effect on the integrity of the cell wall of Pseudomonas aeruginosa ATCC 9027 (a susceptible strain) as shown by electron microscopy using negative-staining, thin-sectioning, and freeze-fracture techniques. The disruption occurred in a sequential manner, moving from the outer membrane to the inner membrane, and could result in lysis of the cell. During this process the outer membrane lost 34% of its total protein and 30% of its lipopolysaccharide (measured as 2-keto-3-deoxyoctonate) upon exposure to 25 micrograms of gentamicin per ml for 15 min. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the outer membrane proteins showed altered banding patterns after exposure to gentamicin. Atomic absorption spectrophotometry revealed a decrease in magnesium and calcium content (18 and 38%, respectively) in the cell envelopes after gentamicin treatment. It is proposed that gentamicin displaces essential metal cations within the outer membrane, consequently destabilizing and extracting organic constituents. Small transient holes are thereby produced which make the outer membrane more permeable to the antibiotic and which expose the protoplast to high concentrations of gentamicin. This membrane effect may contribute to the effects of protein synthesis inhibition during the killing process.

Cell Membrane↗
PubMed1984

Scintigraphic evaluation of giant cell tumor of bone.

Technetium-99m methylene diphosphonate bone scans were performed in 21 patients with giant cell tumors of bone. All tumors showed increased radiophosphate uptake, often more intense at the tumor periphery than in its center. However, radionuclide bone scanning often overestimated intraosseous tumor extent as a result of increased tracer uptake beyond true osseous tumor limits. In addition, it failed to detect soft-tissue tumor extension in nine patients. Therefore, scintigraphy is less useful than either computed or conventional tomography in planning surgical margins of giant cell tumors. Gallium-67 citrate scans obtained in seven patients showed slight uptake in four tumors and no uptake in three. Radiogallium imaging is thus of limited use in evaluation of suspected giant cell tumors of bone.

Adolescent↗
PubMed1982

The cost of managing digital diagnostic images.

A study of the cost of recording and archiving digitally formatted diagnostic images is presented for an academic radiology department serving a 614-bed university hospital and a large outpatient population. The radiological examinations include computed tomography, nuclear medicine, ultrasound, and digital radiography. The archiving management strategies studied include the combined use of computer magnetic tapes, computer disc storage, and multiformat video film recordings. The estimated cost per patient for the archiving of digital diagnostic images is presented.

Archives↗
PubMed1982

A peripheralized digital image management system: prospectus.

The number of diagnostic radiology examinations being performed on digitally formatted imaging equipment is continually increasing. However, most digital data are recorded as analogue images and the films stored in a central file. The dynamic range of raw digital data is lost. Currently, the space and cost requirements for storage of all digital data have discouraged most users from attempting it. This article presents the concepts and describes the requirements and initial fabrication of a system that will capture and retain all digital data using a network of peripheralized image acquisition, display, and storage devices. Any piece of digitally formatted equipment can be interfaced into the system. A real-time computer capability provides that any digital examination can be reviewed at any display station for up to 10 days.

Computers↗
PubMed1981

Measurement accuracy of proximal femoral geometry using biplanar radiography.

Experimental testing indicates that the neck-shaft angle of the proximal femur can be reliably measured from biplanar radiographs, but torsion cannot. Calculated torsion varies significantly from true torsion as a function of the error created by femoral rotation, while the calculated neck-shaft angle is invariant with respect to rotation even though the calculated neck-shaft angle is mathematically dependent on calculated torsion. Theoretical considerations support this finding and demonstrate for the first time why it is true. This study demonstrates that clinical measurements of frontal plane hip deformities using existing biplanar radiography are quite accurate, but clinical measurements of torsional abnormalities are unreliable. These errors can be minimized if investigators specify the angle of the lateral X-ray beam on the anteroposterior film using methods described in this paper and if patient position is radiographically verified. The magnitude and types of errors inherent in biplanar radiography should be considered in planning preoperative strategies and in postoperative assessments of hip geometry.

Femur↗
PubMed1981

Radiographic projections for the diagnosis of arthritis of the hands and wrists.

One hundred consecutive sets of radiographs with the hands halfway supinated (Nørgaard's view) were reviewed retrospectively without knowledge of the clinical diagnosis to determine the value of this view for diagnosis of rheumatoid arthritis. Indistinct cortex at specific sites, reported to be a sensitive indicator of rheumatoid arthritis, was seen in 81% of rheumatoid patients: however, it was not specific for rheumatoid arthritis, being present in both inflammatory and noninflammatory arthritides. These changes are apparently due to variations in cortical morphology and are not true erosions. Definite erosions, which were more specific for inflammatory arthritis, were seen at the same sites; however, erosions could be identified on postero-anterior radiographs in 14 of the 16 cases in which they were seen on the Nørgaard views.

Adolescent↗
PubMed1977

A new low dose mammography technique.

Reduction of radiation dosage to patients undergoing mammography is very important, especially when large-scale screening projects for early detection of breast carcinoma are considered. A new low dose mammographic technique employing Kodak XG film and Industrex F2 intensifying screen in a vacuum package has been evaluated in 533 patients. This Kodak system was found to provide excellent diagnostic quality image, and to be an acceptable technique for mammography.

Breast Neoplasms↗