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Biomedical subjects

M R Williamson

Publications and source records attributed to M R Williamson.

At least 37 records · Page 2Linked to original sources
PubMed1992

Thyroid nodules in the population living around Chernobyl.

OBJECTIVE: To determine the baseline incidence, prevalence, and characteristics of thyroid nodules in the population living around the Chernobyl nuclear power plant and to compare the findings with unexposed populations. DESIGN: Prevalence study. Population samples from seven highly contaminated villages were compared with six nearby control villages of the same size and type. The data were obtained as part of the International Chernobyl Project conducted in 1990. SETTING: The study was conducted 4.5 years after the Chernobyl reactor accident that released large quantities of radionuclides, including radioiodine. PATIENTS OR OTHER PARTICIPANTS: Population samples of approximately 100 persons residing in both highly contaminated villages and control villages since the accident were compared. Individuals were selected on the basis of birth date as being 5, 10, 40, or 60 years old at the time of the study. All persons selected underwent a thyroid examination. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Two main outcome measures were used, both for thyroid nodularity: clinical palpation and high-resolution ultrasonography. RESULTS: There was no significant difference in thyroid nodularity between the study groups. Nodules were palpated in 0.7% of children and 2.9% of adults. Discrete nodules were found by ultrasonography in 0.5% of children and 14.9% of adults. Multinodular goiter was found in 3% of adults. Nodules were more common in females. CONCLUSIONS: Four and a half years after the Chernobyl accident, the incidence, prevalence, and characteristics of thyroid nodules were the same in population samples from both highly contaminated and control settlements and similar to results reported for unexposed populations in other countries.

Accidents↗
PubMed1992

Differential expression of neural cell adhesion molecule and cadherins in pancreatic islets, glucagonomas, and insulinomas.

The endocrine cells of the pancreas develop from the endoderm and yet display several characteristics of a neuronal phenotype. During embryonic life, ductal epithelial cells give rise to first the glugagon-producing cells (alpha-cells) and then cells that express insulin (beta-cells), somatostatin (delta-cells), and pancreatic polypeptide (PP-cells) in a sequential order. The endocrine cells are believed to arise from a stem cell with neuronal traits. The developmental lineage from a common neuron-like progenitor is evidenced by: transient coexpression of more than one cell type-specific hormone in immature cells, expression of neuronal markers during islet cell development, and the pluripotentiality of clones of insulinoma cells to develop into cells expressing other islet cell hormones. The four mature endocrine cell types assume a particular organization within the islets of Langerhans in a process where cell adhesion molecules are involved. In this study we have analyzed the expression of neural cell adhesion molecule (NCAM) and cadherin molecules in neonatal, young, and adult rat islet cells as well as in glucagonomas and insulinomas derived from a pluripotent rat islet cell tumor. Whereas primary islet cells at all ages express unsialylated NCAM and E-cadherin, as do insulinomas, the glucagonomas express the polysialylated NCAM, which is characteristic for developing neurons. The glucagonomas also lose E-cadherin expression and instead express a cadherin which is similar to N-cadherin in brain. Insulinoma cells express E-cadherin but differ from primary islet cells by expressing a second cadherin molecule, which is similar to N-cadherin. The expression of NCAM and cadherin isoforms in the glucagonoma suggest that this transformed alpha-cell type has converted to an immature phenotype with strong neuronal traits, reflecting the early palce of glucagon-producing cells in the islet cell lineage. In contrast, insulinoma cells are more islet-like in their phenotype and show less neuronal traits.

Animals↗
PubMed1992

Magnetic resonance imaging of musculoskeletal tumors.

The Scientific Board of the California Medical Association presents the following inventory of items of progress in radiology. Each item, in the judgment of a panel of knowledgeable physicians, has recently become reasonably firmly established, both as to scientific fact and important clinical significance. The items are presented in simple epitome, and an authoritative reference, both to the item itself and to the subject as a whole, is generally given for those who may be unfamiliar with a particular item. The purpose is to assist busy practitioners, students, researchers, or scholars to stay abreast of these items of progress in radiology that have recently achieved a substantial degree of authoritative acceptance. Whether in their own field of special interest or another. The items of progress listed below were selected by the Advisory Panel to the Section on Radiology of the California Medical Association, and the summaries were prepared under its direction.

Bone Neoplasms↗
PubMed1991

Revised genomic consensus for the hypermethylated CpG island region of the human L1 transposon and integration sites of full length L1 elements from recombinant clones made using methylation-tolerant host strains.

Efficient recovery of clones from the 5' end of the human L1 dispersed repetitive elements necessitates the use of deletion mcr- host strains since this region contains a CpG island which is hypermethylated in vivo. Clones recovered with conventional mcr+ hosts seem to have been derived preferentially from L1 members which have accumulated mutations that have removed sites of methylation. We present a revised consensus from the 5' presumptive control region of these elements. This revised consensus contains a consensus RNA polymerase III promoter which would permit the synthesis of transcripts from the 5' end of full length L1 elements. Such potential transcripts are likely to exhibit a high degree of secondary structure. In addition, we have determined the flanking sequences for 6 full length L1 elements. The majority of full length L1 clones show no convincing evidence for target site duplication in the insertion site as commonly observed with truncated L1 elements. These data would be consistent with two mechanisms of integration of transposing L1 elements with different mechanisms predominating for full length and truncated elements.

Base Sequence↗
PubMed1991

Osteomyelitis: sensitivity of 0.064 T MRI, three-phase bone scanning and indium scanning with biopsy proof.

We compared the ability of magnetic resonance imaging (MRI) using a 0.064 T permanent magnet, three-phase bone scanning, and indium-labeled white blood cell (111In-WBC) scanning, to diagnose osteomyelitis. Twenty-three patients underwent biopsy. All patients were examined at presentation with all three modalities. Sensitivities for each modality were calculated using biopsy as a gold standard. The results were 72% for MRI, 68% for bone scan, and 45% for 111In-WBC. Specificities were not calculated because of lack of negative biopsies. MRI was as sensitive as bone scanning in the diagnosis of osteomyelitis. All modalities had lower than previously reported sensitivities for imaging osteomyelitis.

Biopsy↗
PubMed1991

Eosinophilia-myalgia syndrome: findings on chest radiographs in 18 patients.

Findings on chest radiographs of 18 patients with the eosinophilia-myalgia syndrome were compared and correlated with peak eosinophil counts. Nine patients had normal chest radiographs. Of the nine patients with abnormal chest radiographs, three had fine, irregular linear opacities in the lungs (the opacities were most noticeable at the bases); three had similar irregular linear opacities and pleural effusions; and three had pleural effusions and confluent opacities. One patient demonstrated an enlarged heart; no pulmonary edema was seen in this patient or in any others. Although the mean recorded eosinophil cell counts were higher in those patients with abnormal chest radiographs (6,340 vs 5,454/mm3 [6.3 vs 5.4 x 10(9)/L]), the difference was not statistically significant.

Adult↗
PubMed1990

Osteoporosis: diagnosis by plain chest film versus dual photon bone densitometry.

Readers of chest radiographs often comment on the presence of osteoporosis. We have hypothesized that diagnoses of osteoporosis from chest films are not reliable even when made by experienced radiologists. To test this hypothesis, we had nine radiologists estimate the degree of bone density seen on 45 lateral chest films. We compared their estimates of bone density to the results of dual photon bone densitometry of the lumbar spine. We found that there was little ability to accurately diagnose osteoporosis by chest film since the group of nine readers achieved accuracies ranging from 0.59 to 0.64. Therefore, we feel it is unjustified to comment upon the presence or absence of osteoporosis on the basis of chest films.

Absorptiometry, Photon↗
PubMed1990

Contamination of a soft-drink manufacturing plant by 210Po.

An investigation was undertaken of the contamination of equipment and flooring by 210Po, released from a static eliminator source, at a soft-drink manufacturing plant. The detection and establishment of extent of contamination, development of decontamination and control procedures and difficulties in implementing those procedures are discussed. Additionally, the likely health effects to workers are assessed. The removal and disposal of contaminated equipment, the use of epoxy compound on the floor to seal fixed contamination and the implementation of a 5-y monitoring program are detailed. The estimated cost of decontamination is provided.

Australia↗
PubMed1990

Scintigraphic appearance of uncommon soft-tissue osteogenic sarcoma metastases.

The advent of improved chemotherapy has changed the natural course of osteosarcoma. The role of bone scintigraphy in the workup of metastatic osteosarcoma is being re-evaluated. Extra-osseous osteogenic sarcoma metastases, particularly pulmonary metastases, are known to accumulate bone-avid agents. In this case, there is also uptake by noncalcified metastases to the brain and to soft tissues of the leg and arm which has not been previously reported. Correlation with computed tomography and magnetic resonance imaging is made.

Adult↗
PubMed1989

MRI in the evaluation of spina bifida patients in the remote period after meningomyelocele repair.

MRI was performed on 22 patients ranging in age from 3 months to 16 years who had closure of their meningomyelocele shortly after birth. These patients had developed new clinical findings suggestive of spinal cord dysfunction. MRI showed low placement of the spinal cord in all 22. Six patients had lipomas, five had diastematomyelia and six had hydromyelia. Four patients had an obviously dysplastic terminal cord.

Adolescent↗
PubMed1989

Technetium-99m RBC bleeding images in normal subjects: confusion with gastrointestinal bleeding sites.

The normal appearance of a gastrointestinal bleeding study using labeled red blood cells has been discussed frequently, but the actual appearance is not well known. In this atlas article, the authors report on unusual findings in non-bleeding subjects and have tabulated the visualization of various structures. Vascular structures other than the aorta and inferior vena cava were seen in 42 of 48 patients. One or both kidneys were seen in 10 (21%) of 48 patients. The urinary bladder was seen in 23 (48%) of 48 patients, although gastric activity caused by free pertechnetate was never observed.

Erythrocytes↗
PubMed1989

Localization of adrenal and extra-adrenal pheochromocytomas by magnetic resonance imaging.

We found magnetic resonance imaging helpful in the localization of both an adrenal and an extra-adrenal pheochromocytoma, since these tumors produced a high-intensity "light bulb" image. MRI is an excellent method for localizing pheochromocytomas because it detects adrenal and extra-adrenal pheochromocytomas missed by computerized tomography and adrenal-renal ultrasonography, and because the high-intensity MRI signal generated by pheochromocytomas is useful in differentiating them from nonfunctioning adrenal masses in hypertensive patients.

Adolescent↗