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Biomedical subjects

C R Wilson

Publications and source records attributed to C R Wilson.

At least 73 records · Page 4Linked to original sources
PubMed1986

Digital and conventional chest images: observer performance with Film Digital Radiography System.

The Film Digital Radiography System (FilmDRS) is a device with a laser optical film digitizer, 2,000 X 2,000 X 12-bit memory, and a 1,000-line video display. To evaluate the adequacy of this device for general radiography of the chest, four readers independently analyzed both radiographs and the corresponding video display of the digitized chest images of 150 patients, consisting of 100 images of abnormalities and 50 normal images. The overall results indicate equal sensitivity for the two systems. The FilmDRS, with interactive windowing, proved superior in the detection of hilar and mediastinal disease. X-ray film was superior in allowing detection of hyperlucent states. There was equivalent sensitivity for other disease categories. Superior specificity was achieved with conventional radiographs.

Analog-Digital Conversion↗
PubMed1986

Pseudotumor of the craniovertebral junction associated with chronic subluxation: MR imaging studies.

Masses at the craniovertebral junction generally have serious prognostic implications. However, the authors studied three patients who had chronic atlantoaxial subluxation from either degenerative disease or congenital dysplasia of the dens and who also had benign fibrous masses in this region, confirmed at surgery. The association of masses of the craniovertebral junction with chronic atlantoaxial subluxation raises the possibility that the underlying cause of the masses is chronic mechanical irritation. All patients were imaged with metrizamide myelography and adjunctive computed tomography (CT), then by magnetic resonance (MR) imaging. MR images were not only superior to myelograms and CT scans in delineating the exact extent of the lesions, they also indicated the benign, fibrous nature of the masses.

Adult↗
PubMed1986

The effect of varying high pass filter parameters on the detectability of isolated pulmonary nodules in digitized chest images.

The effect of image processing of digital radiographic data on lesion detectability in clinical images has not been systematically studied. In this experiment, we evaluated a low frequency suppression filter program applied to CT digital radiographic localization images (General Electric Scoutview). Three different filter parameters affecting edge enhancement and local image contrast were applied to a set of digital chest images. A standard observer detection experiment comparing the variously filtered digital images and standard chest radiographs in the detection of lung nodules (11 peripheral lung fields, one superimposed on aortic arch) was performed. Standard chest radiography was more sensitive than the digital chest images, although some improvement was noted with increase in local image contrast and edge enhancement. Both image formats were equally specific. Image processing would be better evaluated using a digital imaging system with better performance parameters.

Analog-Digital Conversion↗
PubMed1985

Chromosomal-DNA amplification in Bacillus subtilis.

Tetracycline-resistant (Tetr) mutants RAD1, RAD2, RAD6, and RAD7 were isolated from Bacillus subtilis BC92 after protoplasting, polyethylene glycol treatment, and regeneration on a medium containing tetracycline. The Tetr phenotype in RAD1, RAD2, and RAD6 was very stable with less than 5% loss of resistance after 30 generations of growth in the absence of selection. Of the four isolates, three contained amplified chromosomal DNA closely associated with the Tetr phenotype. The intensity of restriction fragments present in HindIII and EcoRI digests of chromosomal DNA from RAD1, RAD6, and RAD7 indicated the presence of tandemly duplicated DNA. Disparity in the size and number of amplified fragments suggested that the tandemly duplicated DNA is different in all three isolates. The sizes of the duplicated DNA present in RAD1, RAD6, and RAD7 were estimated to be 10, 19, and 20 kilobases, respectively. No amplified DNA was detected in RAD2. Results of transductional-mapping studies with PBS1 showed that the tetracycline resistance (tet) loci of RAD1, RAD2, and RAD6 all mapped near the origin of chromosomal replication and close to the guaA locus. Amplified DNA characteristic of RAD1 and RAD6 was cotransduced with the tet locus. Cotransfer of amplified DNA with the guaA locus or other nearby loci in the absence of tet was not observed. In every case, loss of Tetr was accompanied by loss of amplified DNA. A possible explanation for the occurrence of the amplified DNA is presented.

Bacillus subtilis↗
PubMed1983

Perceptual discrimination and reaction time in hallucinatory schizophrenics.

Perceptual discrimination tasks were administered to a group of normal control subjects and the following three groups of schizophrenic subjects: those currently experiencing auditory hallucinations, those who experienced auditory hallucinations in the past but not at present, and those who never experienced auditory hallucinations. No one who ever experienced visual hallucinations was included. Reaction times (RTs) and accuracy in an auditory and in a visual perceptual discrimination task were recorded. The normal subjects were generally more accurate and had faster RTs than the schizophrenic groups. Among the schizophrenic groups, the currently hallucinatory group was generally most accurate. Also, their RTs early in the session were faster than those of the other schizophrenic subjects in the auditory, but not the visual, task. Unlike the other schizophrenic subjects, the currently hallucinatory group displayed faster auditory, as compared with visual, RTs throughout the session. The results point to altered processing of auditory information during the time schizophrenic subjects experience auditory hallucinations.

Adult↗
PubMed1982

Microbial hazards associated with bean sprouting.

The behaviour of microorganisms was studied in mung beans and alfalfa seeds before and after germination in modified, commercially available bean-sprouting kits. The microorganism were enumerated by the aerobic plate count (APC) and by total yeast and mold count procedures. Salmonella species were artificially inoculated into selected samples and were enumerated by the most probable number (MPN) method. After germination of the beans or seeds into mature sprouts, significant increases were noted in APCs and in MPN values of Salmonella species. Although counts of yeasts and molds did not increase significantly after germination, these samples show an increase in toxic Aspergillus flavus and potentially toxic Alternaria species. The presence of toxic Penicillium cyclopium molds also increase substantially in 5 samples of a single brand of mung beans. Analysis of selected sprout samples, however, showed no presence of aflatoxin.

Aflatoxins↗
PubMed1981

The effect of varying spatial resolution on the detectability of diffuse pulmonary nodules. Assessment with digitized conventional radiographs.

Detection and discrimination of miliary disease and small pulmonary nodules were tested at six levels of spatial resolution varying between 0.3 and 2.5 l.p./mm, and receiver operating characteristic (ROC) curves were generated. The test images were obtained by digitizing selected normal and abnormal standard film/screen radiographs. Although there was no statistically significant difference in observer performance between 0.5 and 2.5 l.p./mm, the findings may have clinical relevance. Further observer detection studies of different disease processes are planned to help formulate performance standards for an electric digital radiographic device for chest imaging.

Diagnosis, Differential↗
PubMed1981

Interlaboratory evaluation of the AOAC method and the A-1 procedure for recovery of fecal coliforms from foods.

An interlaboratory evaluation was made of the 96 h AOAC method and the 24 h A-1 procedure for the enumeration of fecal coliforms in samples of yellow corn meal, rye flour, mung beans, raw ground beef, and raw oyster homogenate. Results indicated that the efficiency of the A-1 procedure, measured in terms of recovery of fecal coliforms, and the reproducibility of that recovery were dependent on the particular food being analyzed. Accordingly, until its efficiency can be more fully demonstrated, the A-1 procedure is recommended only as a screening procedure for fecal coliforms in foods.

Bacteriological Techniques↗
PubMed1981

Pre-enrichment broths for recovery of Salmonella from milk chocolate and edible casein: collaborative study.

A collaborative study was conducted to compare the relative efficiency of nonfat dry milk with brilliant green dye (NFDM-BG and buffered peptone water (BPW) as pre-enrichment broths for recovery of Salmonella from milk chocolate. Lactose broth and modified lactose broth with added 1% NaHCO3 and brilliant green dye were compared as pre-enrichment broths for recovery of Salmonella from edible casein. Two sets of 8 samples each of milk chocolate, containing initial levels of Salmonella ranging from less than 0.03 to 43 organisms/g, were examined by 13 collaborators. Of 104 determinations, 102 (98.1%) and 100 (96.2%) using NFDM-BG and BPW, respectively, were in agreement with sample results of the control laboratory. Two sets of 7 samples each of edible casein, containing initial levels of Salmonella ranging from less than 0.03 to 93 organisms/g, were also examined by the 13 collaborators. Of 91 determinations, 87 (95.6%) and 88 (96.7%) using lactose broth and modified lactose broth, respectively, were in agreement with sample results of the control laboratory. For recovery of Salmonella, therefore, NFDM-BG pre-enrichment is recommended for milk chocolate, and lactose broth is recommended for casein. The proposed revision of official final action method 46.054-46.067 has been adopted official first action.

Cacao↗
PubMed1981

Comparative efficiency of brilliant green, bismuth sulfite, Salmonella-Shigella, hektoen enteric, and xylose lysine desoxycholate agars for the recovery of Salmonella from foods: collaborative study.

The relative efficiency of brilliant green (BG), bismuth sulfite (BS), Salmonella-Shigella (SS), xylose lysine desoxycholate (XLD), and Hektoen enteric (HE) agars for the recovery of Salmonella from 5 foods was collaboratively studied in 11 laboratories. The analytical efficiency of various paired combinations of the 5 agars was statistically compared according to 3 parameters: (1) productivity or recovery of Salmonella, (2) rate of enumeration of cultures that were false positive for Salmonella, and (3) rate of enumeration of false-negative reactions. In descending order of productivity, the sequential ranking was BS, XLD, HE, BG, and SS agars. In ascending order, the rates of false-positive reactions based on a statistical analysis of paired agar combinations was HE, BS, BG and XLD (tie), and SS agars. Analogously, in ascending order, the sequence of false-negative reaction rates was BS, XLD, HE, BG, and SS agars. The combination of BS, XLD, and HE agars is more efficient for recovery of Salmonella from foods than is the present official combination of BG, BS, and SS agars. The revision of official final action method 46.054 to replace the combination of BG, BS, and SS agars with a combination of BS, XLD, and HE agars has been adopted official first action.

Agar↗
PubMed1980

Demonstration of the normal extrahepatic biliary tract with computed tomography.

When optimum computed tomography (CT) technique and computed angiotomography are utilized, the normal extrahepatic biliary ducts (equal to or less than 6 mm in diameter in patients without cholecystectomy) can be demonstrated in approximately 30% of clinical scans. Measurement of the anteroposterior diameter of the bile duct is more accurate than recording the transverse diameter, since the apparent transverse dimension will vary depending on the orientation of the duct in the plane of section. Phantom studies indicate that the absolute error of measurement is approximately one pixel diameter irrespective of duct diameter. The normal and abnormally dilated extrahepatic biliary ducts should be distinguished with CT.

Cholangiography↗
PubMed1980

High resolution computed tomography of the temporal bone.

The radiation dose and the anatomic detail of computed tomography (CT) and conventional tomography were studied in 18 patients with suspected acoustic neuroma, cholesteatoma, malignant tumor, and temporal bone fracture. It is concluded that CT is the technique of choice in patients suspected of having acoustic neuromas or malignant tumors of the temporal bone, while hypocycloidal tomography should be used to evaluate pateints with otosclerosis, small cholesteatomas, and inflammatory disease of the middle ear. For diagnosing fractures and large cholesteatomas, CT and conventional tomography are complementary.

Cholesteatoma↗
PubMed1979

Bacteriological survey of sixty health foods.

A bacteriological survey was performed on 1,960 food samples encompassing 60 types of health foods available in the Baltimore-Washington, D.C., metropolitan area. No consistent bacteriological distinction (aerobic plate counts, total coliform and fecal coliform most probable numbers) was observed between foods labeled as organic (raised on soil with compost or nonchemical fertilizer and without application of pesticides, fungicides, and herbicides) and their counterpart food types bearing no such label. Types and numbers of samples containing Salmonella were: sunflower seeds, 4; soy flour, 3; soy protein powder, 2; soy milk powder, 1; dried active yeast, 1; brewers' years, 1; rye flour, 1; brown rice, 1; and alfalfa seeds,1. The occurrence of this pathogen in three types of soybean products should warrant further investigation of soybean derivatives as potentially significant sources of Salmonella.

Bacteria↗
PubMed1979

Relative productivity of five selective plating agars for the recovery of Salmonella from selected food types.

During a 3-year period, the relative productivity of brilliant green (BG), bismuth sulfite (BS), Salmonella-Shigella (SS), Hektoen enteric (HE), and xylose lysine, desoxycholate (XLD) agars for recovering Salmonella from 9 food types was determined. Following pre-enrichment, selective enrichment of food samples in tetrathionate broth followed by streaking to BS agar was the single most productive selective enrichment broth-agar combination for recovery of Salmonella in 5 of these food types. A study of the performance of these 5 agars used individually and in various combinations, showed that none of the 5 agars used individually nor any of the possible paired combinations of these agars could be used to satisfactorily detect Salmonella in the 9 food types. The use of all 5 agars was not necessary because one combination of 4 agars (BG, BS, HE, and XLD) recoverd 100% of the Salmonella isolates, as compared with the number of Salmonella isolates recovered by the 5-agar combination, in each food category. This particular 4-agar combination, along with two 3-agar combinations (BG, BS, and XLD agars, and BS, HE, and XLD agars), were each able to recover more Salmonella isolates, than the combination of BG, BS, and SS agars, the combination currently recommended by the AOAC. Finally, the relative costs of using these agars, singly and in various combinations, were determined.

Agar↗
PubMed1978

Usefulness of the stomacher in a microbiological regulatory laboratory.

The relative efficiency of the Waring blender, the Stomacher 400, and the Stomacher 3500 for preparing food samples for microbiological analysis was studied. Comparative aerobic plate count (APC) values were determined on 671 samples, representing 30 categories of foods. Of the 26 categories of nonfatty foods, the blender gave significantly higher geometric mean APC values than those given by the Stomacher 400 and the Stomacher 3500 in 65 and 69 percent of the categories, respectively. In a comparison of the two Stomacher models, the Stomacher 400 gave significantly higher geometric mean APC values than these given by the Stomacher 3500 in 73 percent of the food categories. Addition of Tween 80 to four categories of fatty foods at concentrations of 0.5, 1.0, and 2.0 percent did not raise the APC values given by either model of stomacher to the levels given by the Waring blender. Overall, the efficiency of both models of Stomacher, relative to the blender and to each other, was specific and depended upon the particular food being analyzed.

Bacteria↗