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Biomedical subjects

M R Hanson

Publications and source records attributed to M R Hanson.

99 records · Page 6Linked to original sources
PubMedDate not supplied

A truncated recombination repeat in the mitochondrial genome of a Petunia CMS line.

Repeated sequences known as recombination repeats are present in the majority of plant mitochondrial genomes. Two recombination repeat sequences from Petunia have been analyzed. The two repeats are virtually identical over 1.42 kb. One of the repeats is truncated and is likely to have arisen from a rare recombination event in the full-length repeat. Two sequence-blocks within the Petunia repeat are highly similar to sequences in the 5' flank of several plant mitochondrial genes. No sequence motifs are shared by the Petunia repeat and other sequenced plant mitochondrial recombination repeats, suggesting that the recombination occurs by an homologous, rather than a site-specific, mechanism.

Base Sequence↗
PubMedDate not supplied

Hepatitis B surveillance in employees of a community blood center.

Over a period of 10 years, 185 employees of a community blood center were screened for evidence of hepatitis B virus (HBV) infection. Included were laboratory personnel (64%), phlebotomists (27%), and administrative employees (9%). HBV markers were detected in 5.8 percent of the individuals at the time of enrollment in the study. During the study period, seven clinical cases of HBV occurred, all in laboratory personnel. Four of the infections were in personnel involved primarily in donor processing. The other three were in individuals working in research areas. In addition, four asymptomatic HBV infections were identified on the basis of seroconversion from anti-HBs negative to positive. The annual incidence of HBV infection per 100 tested employees at risk (1.6%) indicates that blood bank personnel, despite their frequent exposure to blood, are not at high risk of developing HBV infection.

Allied Health Personnel↗
PubMedDate not supplied

Evaluation of routine anti-HBc screening of volunteer blood donors: a questionable surrogate test for non-A, non-B hepatitis.

Routine antibody to hepatitis B core antigen (anti-HBc) screening, recommended as a surrogate test to identify potential carriers of non-A, non-B hepatitis, was evaluated on 22,346 blood donors using currently available enzyme immunoassay (EIA) reagents. Of the 2 percent found reactive, the majority had cutoff-to-sample absorbance ratios less than 2.0 and less than one-half had anti-HBc when tested by a radioimmunoassay (RIA) method. Only one of 2877 units donated previously by the reactive donors was implicated in a transfusion associated hepatitis case. These results raise questions about the use of currently available anti-HBc reagents as a surrogate test for non-A, non-B hepatitis.

Blood Donors↗
PubMedDate not supplied

Mitochondrial gene organization and expression in petunia male fertile and sterile plants.

In cytoplasmic male-sterile Petunia lines, NADH dehydrogenase subunit 3 (nad3) and ribosomal protein S12 (rps12) are cotranscribed with the chimeric gene pcf and located in the region of the mitochondrial genome associated with cytoplasmic male sterility (CMS) in Petunia. In fertile Petunia line 3704, the genes for nad3 and rps12 are cotranscribed with an unidentified open reading frame (orf143). In the homologous region of fertile line 3699, there is an ORF that lacks a genomic DNA-encoded stop codon; instead an RNA editing event creates a stop codon, resulting in an ORF of 161 codons. While expressed sequences homologous to this open reading frame can be detected in sterile lines, a contiguous orf143/orf161 gene does not exist in the CMS-encoding mitochondrial genome. Transcription at the CMS-associated pcf locus and the fertile orf143/nad3/rps12 locus is complex, with multiple 5' and 3' termini. The presence of the nuclear fertility restorer gene affects the abundance of a transcript class with 5' termini--121 nucleotides before the pcf start codon, and greatly reduces the abundance of a pcf gene product with apparent molecular mass of 25 kDa which is present in both vegetative and reproductive tissues of CMS plants. In addition to the 25 kDa protein product, small amounts of precursor and processed pcf products with higher molecular mass have been detected; their possible role in the CMS phenotype is unknown. Current hypotheses for the mechanism of action of CMS-associated and fertility restorer genes are discussed.

Amino Acid Sequence↗
PubMedDate not supplied

Brain events associated with mitral valve prolapse.

The clinical and laboratory features of 24 patients with proven mitral valve prolapse (MVP) and brain dysfunction are reported. The age range of affected patients was between 20 and 63 years (average of 43) and 70 percent were women. MVP was documented prior to the brain illness in only 4 patients. The majority of patients experienced bland cerebral infarction. Disorders also included transient ischemic attacks, cerebellar infarctions, parencymatous and subarachnoid hemorrhage, seizures and retinal artery occlusion. Significant risk factors for stroke other than MVP were lacking in the patient group. Cerebral angiograms occasionally showed distal occlusions of small arteries suggesting embolic brain lesions. Our study suggests that MVP is a risk factor for stroke. We recommend echocardiography in patients with cerebral ischemia who lack clear, recognized risk factors for stroke. We believe the basis for this brain disorder to be emboli from damaged mitral valve leaflets.

Adult↗
PubMedDate not supplied

Central nervous system complications of coronary artery bypass graft surgery: prospective analysis of 421 patients.

A prospective analysis of 421 patients undergoing coronary artery bypass graft (CABG) surgery as the sole cardiac procedure was carried out to assess the frequency of central nervous system (CNS) complications. In all, 451 variables were assessed in each patient. Stroke occurred in 5.2% but was severe in only 2%. Prolonged encephalopathy occurred in 11.6% but usually resolved before discharge. No statistically significant pre- or intraoperative risk variables for CNS complications were found; specifically, age or pump times in excess of two hours were not significant factors. Postoperative use of an intraaortic balloon pump and pressor agents were significantly correlated with prolonged encephalopathy. The frequency of CNS injury in CABG surgery is similar to that in other forms of open heart surgery, and there has been little change in the frequency of CNS complications over the past seven years. Possible mechanisms of CNS damage during CABG surgery are discussed.

Adult↗
PubMedDate not supplied

Anterior uveitis and multiple sclerosis.

Three patients with clinically definite multiple sclerosis and uveitis were studied. The uveitis presented as inflammation of the anterior segment of the eye (iridocyclitis) and was characterized by large keratic precipitates and posterior synechiae, consistent with a granulomatous iridocyclitis. Clinical and laboratory evidence militated against other central nervous system diseases often associated with uveitis including neurosarcoidosis, Behçet's syndrome, Vogt-Koyanagi-Harada disease, neurosyphilis, and tuberculosis. Further attention should be directed to the possibility of granulomatous anterior uveitis in patients with multiple sclerosis.

Adolescent↗