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Biomedical subjects

J R McDowell

Publications and source records attributed to J R McDowell.

17 recordsLinked to original sources
PubMed2001

Reconciling patterns of inter-ocean molecular variance from four classes of molecular markers in blue marlin (Makaira nigricans).

Different classes of molecular markers occasionally yield discordant views of population structure within a species. Here, we examine the distribution of molecular variance from 14 polymorphic loci comprising four classes of molecular markers within approximately 400 blue marlin individuals (Makaira nigricans). Samples were collected from the Atlantic and Pacific Oceans over 5 years. Data from five hypervariable tetranucleotide microsatellite loci and restriction fragment length polymorphism (RFLP) analysis of whole molecule mitochondrial DNA (mtDNA) were reported and compared with previous analyses of allozyme and single-copy nuclear DNA (scnDNA) loci. Temporal variance in allele frequencies was nonsignificant in nearly all cases. Mitochondrial and microsatellite loci revealed striking phylogeographic partitioning among Atlantic and Pacific Ocean samples. A large cluster of alleles was present almost exclusively in Atlantic individuals at one microsatellite locus and for mtDNA, suggesting that, if gene flow occurs, it is likely to be unidirectional from Pacific to Atlantic oceans. Mitochondrial DNA inter-ocean divergence (FST) was almost four times greater than microsatellite or combined nuclear divergences including allozyme and scnDNA markers. Estimates of Neu varied by five orders of magnitude among marker classes. Using mathematical and computer simulation approaches, we show that substantially different distributions of FST are expected from marker classes that differ in mode of inheritance and rate of mutation, without influence of natural selection or sex-biased dispersal. Furthermore, divergent FST values can be reconciled by quantifying the balance between genetic drift, mutation and migration. These results illustrate the usefulness of a mitochondrial analysis of population history, and relative precision of nuclear estimates of gene flow based on a mean of several loci.

Animals↗
PubMed1999

Spontaneous resolution of a cervicothoracic syrinx in a child. Case report and review of the literature.

A child with near complete spontaneous resolution of a cervicothoracic syrinx and improvement in a Chiari type I malformation without surgical intervention is presented. The child was followed clinically with serial magnetic resonance (MR) imaging and has remained neurologically stable over an 11-year period. To our knowledge, only 3 pediatric cases of spontaneous resolution of a spinal cord syrinx as documented by MR imaging without surgical intervention have been reported. This case contributes to the literature on the natural history of syringes.

Abnormalities, Multiple↗
PubMed1990

Familial meningioma.

A mother and 3 daughters had meningiomas, pathologically confirmed in all but 1 daughter. One of the tumors had mild atypical features, but chromosomal analysis was normal. In 3 of the cases, peripheral chromosomal analysis was normal. There was no evidence of neurofibromatosis.

Aged↗
PubMed1984

Computed tomographic findings in Wernicke-Korsakoff syndrome.

An unconscious patient had a differential diagnosis of coma. Traumatic, metabolic, and infectious origins were considered, but none explained her condition satisfactorily. Clinical features on examination were compatible with Wernicke-Korsakoff syndrome. Her condition improved with supportive treatment and thiamine hydrochloride administration. A computed tomographic scan showed large, symmetric, low-density thalamic lesions, the condition of which improved after three months.

Female↗
PubMed1982

Intracranial extension and spontaneous hemorrhage of a sphenoid plasmacytoma.

A 71-year-old woman with IgG multiple myeloma presented initially with a compression fracture of the thoracic spine. She responded to radiation therapy and chemotherapy with melphalan and prednisone. One year later, she died from a plasmacytoma eroding intracranially from the greater wing of the sphenoid bone with an associated subdural hematoma. Uncal herniation had been preceded for several weeks by facial numbness. Cranial and intracranial plasmacytomas may occur as isolated lesions or as part of multiple myeloma and can present clinically in a variety of ways, most frequently with cranial nerve palsies. Large intracranial extensions may produce cerebral compression and spontaneous hemorrhage similar to that seen with other malignant intracranial neoplasms. The differential diagnosis of changes in level of consciousness in myeloma patients should include increased intracranial extension and spontaneous hemorrhage.

Aged↗
PubMed1980

Heptachlor residue accumulation and depletion in broiler chickens.

Broiler chickens were fed heptachlor in concentrations of 0, 0.01, 0.03, 0.1, and 0.3 mg/kg of the ration for the first 8 weeks of life. There were no adverse effects on health or performance. Residue concentrations in adipose tissue increased rapidly for 1 to 2 weeks and then tended to plateau at concentrations about five times greater than those in the rations. Birds exposed only during the 7th week of life stored 25% as much residue as did the chickens exposed in the 1st week, but the former also ate only 63% as much feed. Fat extracted from liver and muscle contained more residue than did fat extracted from adipose tissue. The ratio of the concentration of heptachlor to its epoxide metabolite was higher in muscle fat than in heptic or abdominal fat. Residue concentrations depleted by about half in the first 4 weeks after cessation of exposure.

Adipose Tissue↗
PubMed1977

Role of the Food and Drug Administration concerning chemical contaminants in animal feeds.

Chemical contamination of animal feeds and feed ingredients is of concern to the Food and Drug Administration. Contamination by industrial chemicals such as polychlorinated biphenyls and polybrominated biphenyls; heavy metals such as lead, cadmium, and mercury; and pesticides such as dieldrin and chlordane exemplify the problem in feeds and the resulting problem of tissue residues in human foods.

Animal Feed↗
PubMed1975

Toxicity of hexachlorobenzene and associated residues in edible animal tissues.

The USDA has detected hexachlorobenzene (HCB) in the body fat of domestic animals and poultry in at least 14 states. In Louisiana, industrial contamination appeared to be largely responsible for the HCB residues detected in cattle. Following the episode in Louisiana, the Environmental Protection Agency (EPA) established an interim tolerance of 0.5 ppm for HCB in the fat of cattle, sheep, goats, and horses. Edible meat products containing HCB at higher concentrations are violative and cannot be used as a source of food for human consumption.

Adipose Tissue↗
PubMedDate not supplied

Educating a patient with diabetes about foot care.

Patient education is a central part of diabetic care. Evaluating the effectiveness of education can be difficult, especially when patients refuse to accept the responsibility that knowledge imparts. Those patients identified as being at risk of developing neuropathic foot ulcers and who are unable or unwilling to accept responsibility for their care need to be closely supervised by the health care team. Patient education should be tailored to encompass cultural and religious factors as far as possible.

Activities of Daily Living↗