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Biomedical subjects

R M Wright

Publications and source records attributed to R M Wright.

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

Clinical utility of magnetic resonance imaging in pediatric neurosurgical patients.

The clinical utility of magnetic resonance imaging in pediatric neurosurgical patients was reviewed in a series of 126 scans. MRI was determined to be superior or equivalent to other imaging techniques in the evaluation of intracranial hypertension, developmental abnormalities, or acute conditions involving the spinal cord. In 74% of the scans performed because of these clinical problems, adequate data were obtained for both specific anatomic diagnosis and surgical planning. The scan proved equivalent to CT in the imaging of structural abnormalities associated with seizure disorders or degenerative conditions. In acute head injuries and generalized infections of the central nervous system, MRI offered no advantage in diagnostic specificity, and had significant logistic limitations.

Acute Disease↗
PubMed1986

MRI of cerebral vein thrombosis in infancy: a case report.

We diagnosed primary idiopathic cerebral vein thrombosis in an infant by MRI. The relative noninvasiveness of the scan, ease of imaging in multiple planes, and good image resolution suggest that the scan may be useful in this disorder.

Humans↗
PubMed1986

Medical imaging of fetal ventriculomegaly.

Five cases of fetal ventriculomegaly are described in detail. Following ultrasonography, either computerized tomography or magnetic resonance imaging was used in an attempt to clarify the structural pathology of the ventriculomegaly. In two patients, a precise diagnosis was achieved while a probable diagnosis was established in a third patient. The diverse etiology of fetal ventriculomegaly in these five cases demonstrates that ancillary medical imaging may be necessary to achieve diagnostic precision prior to therapeutic intervention.

Adult↗
PubMed1985

Sequential bypass grafting for salvage of lower extremities.

Since 1978, 12 patients at our institution have had distal sequential bypass grafting for limb salvage with either polytetrafluoroethylene (PTFE) or reversed saphenous vein and anastomoses to two different distal vessels. Seven patients had had previous vascular operations. One patient died of a stoke in the early postoperative period; a second patient, who was lost to follow-up several months after operation, was presumed to have died. Follow-up is otherwise complete (range seven to 48 months), without early or late limb loss. Results are encouraging and suggest that the sequential anastomotic technique may offer improved results in appropriate limb salvage cases with poor distal runoff.

Aged↗
PubMed1985

Vertebral artery rupture associated with closed head injury. Report of two cases.

The authors report two patients with closed head injury who suffered laceration with rupture of the third portion of the vertebral artery. One patient died suddenly, with angiographic evidence of bilateral vertebral artery rupture. The mechanism of injury to the C1-2 segment of the vertebral artery relating to head and neck injury is discussed.

Adult↗
PubMed1984

Isolation and sequence of the structural gene for cytochrome c oxidase subunit VI from Saccharomyces cerevisiae.

Using synthetic oligodeoxyribonucleic acid probes we have identified and isolated COX6, the structural gene for subunit VI of cytochrome c oxidase from Saccharomyces cerevisiae. The nucleotide sequence of COX6 predicts an amino acid sequence, for the mature subunit VI polypeptide, which is in perfect agreement with that determined previously. The nucleotide sequence of COX6 also predicts that subunit VI is derived from a precursor with a highly basic 40-amino acid NH2-terminal presequence. This precursor has been observed after in vitro translations programmed by yeast poly(A+)RNA. Northern blot analysis of poly(A+) RNA from strain D273-10B reveals that COX6 is homologous to three RNAs of 1800, 900, and 700 bases in length. By means of Southern blot analysis, the cloned gene was shown to be co-linear with yeast chromosomal DNA and to exist in a single copy in the yeast genome. An additional open reading frame, consisting of 82 codons, terminates 22 codons upstream from COX6. It is "in frame" with the COX6 coding region.

Amino Acid Sequence↗
PubMed1983

DNA sequence of the excision sites of a mitochondrial plasmid from senescent Podospora anserina.

During senescence in Podospora anserina, specific gene regions of the mitochondrial genome are excised and amplified. The most prevalent, termed alpha-event senDNA, is a 2600 bp circular molecule which is excised from the contiguous Hae III fragments 23,14 region of the mitochondrial DNA restriction map. We have cloned alpha-DNA plasmid from races s+ and A+ as well as the genomic fragments Hae III 23,14 and have sequenced those regions which constitute the alpha-junction sites. We have found that one excision site (J1) is located 24 bp from the proximal Hae III 23 restriction site and the other (J2) 172 bp from the distal Hae III 14 site. Flanking the alpha-DNA sequences on the mitochondrial genome, there are 10 bp palindromic sequences: CAATATATTG, ending 3 bases from the J1 site, and ATTATATAAT which starts 8 bases from the J2 site. Neither of these 10 bp palindromes are present on the alpha-DNA plasmid. Abutting the J1 site on the alpha-DNA there is a 5 bp sequence (GTGCT) which is repeated 8 bp downstream. In joining the two distal J1 and J2 sites, a 7 bp repeat (ACGTGCG) is produced. These results are discussed within the context of site-specific recombination.

Ascomycota↗
PubMed1983

Integration of mitochondrial gene sequences within the nuclear genome during senescence in a fungus.

Cellular senescence in the ascomycete fungus Podospora anserina is associated with the appearance of an altered mitochondrial genome. Discrete mitochondrial DNA sequences are excised and amplified and isolated as multimerically arranged, head-to-tail repetitions. We have referred to the most frequently observed excision/amplification product as alpha-event senDNA. It is a 2.6-kilobase pair (kbp) monomeric unit (see refs 1, 3, 7) and is often found in senescent mitochondria in conjunction with other excision products. At the final stage of senescence these plasmids constitute virtually all of the DNA present in senescent mitochondria; they have replicated to high copy number at the expense of the young native genome. Because P. anserina is characterized by race-specific timing of senescence (that is, a programme of senescence), we have begun to contrast rapidly and slowly senescing races in terms of senDNA. Here we present evidence that young mitochondria of the rapidly senescing race, A+, possess an extremely high copy number of alpha-event senDNA plasmid in contrast to the more slowly senescing races s+ or s-. Moreover, we observe that during senescence the alpha-event senDNA and the beta-event senDNA (a 9.8-kbp monomer) are transposed to the nucleus and integrated into nuclear DNA. These plasmids contain the coding information for subunits I and III (respectively) of the mitochondrial cytochrome c oxidase. This constitutes the first clear evidence for the active mobilization of genetic elements from the mitochondrion to the nucleus.

Aging↗
PubMed1983

Use of cardiopulmonary bypass for thrombectomy in acute superior vena cava syndrome.

An increasing incidence of nonmalignant, indwelling catheter cases has been reported in relation to superior vena cava syndrome. Such cases may be life-threatening, with rapid development of facial and neck edema and the production of respiratory distress. This is the first reported case of atrial and superior vena caval thrombectomy requiring cardiopulmonary bypass; it is only the second case reported in which operative thrombectomy has been used. Because of the problems associated with an increase in the use of indwelling venous catheters and the satisfactory results we obtained in this case, such an aggressive form of treatment for acute, benign superior vena cava syndrome may be used more frequently in the future.

Journal Article↗
PubMed1983

Coarctation of the abdominal aorta.

Coarctation of the abdominal aorta represents an unusual but surgically treatable form of hypertension. The cause is somewhat controversial but generally can be traced to congenital or acquired origins. A case is presented in which the anomaly appears to be congenital. The variability in anatomy and subsequent treatment are discussed along with appropriate evaluation of the problem.

Journal Article↗
PubMed1982

Are mitochondrial structural genes selectively amplified during senescence in Podospora anserina?

Genetic and transcriptional maps have been constructed for the mitochondrial genome of the Ascomycete Podospora anserina. These data have been plotted on the restriction maps for Sal I, Xho I, Bam HI, Eco RI, BgI II and Hae III. We have characterized and cloned a new and unique senescent mitochondrial DNA (beta-event senDNA) and have organized all of the recognized senDNAs on the genomic maps. We make the observation that all of the known and characterized senDNAs are derived from specific genes or gene regions of the young mitochondrial genome. We have unambiguously assigned the alpha-event senDNA (the 2.6 kb monomer) to the oxi3 gene locus and the beta-event senDNA to the oxi2 gene locus.

Ascomycota↗
PubMed1980

Extent of peptide cross-linking in the peptidoglycan of Neisseria gonorrhoeae.

The extent of peptide cross-linking in peptidoglycan (PG) isolated from various strains of Neisseria gonorrhoeae was examined. Purified PG, specifically labeled in the peptide moiety with [(3)H]diaminopimelic acid (DAP) and labeled in the glycan with [(14)C]glucosamine and [(14)C]muramic acid, was digested completely with Chalaropsis B muramidase. Gel filtration of the digest on connected columns of Sephadex G-50 and G-25 revealed four well-defined peaks corresponding to soluble PG fragments and containing a constant ratio of (3)H to (14)C. On the basis of (i) K(D) values, (ii) amino acid composition, (iii) free amino group analysis of [(3)H]DAP residues, (iv) borohydride reduction, (v) the beta-elimination reaction, (vi) high-voltage electrophoresis, and (vii) paper chromatography in various solvents, the PG fragments were identified as un-cross-linked disaccharide peptide monomer, typical of chemotype I PG, and the corresponding peptide cross-linked dimers, trimers, and tetramers. The percent cross-linking of PG basically reflects the percentage of DAP residues that are involved in peptide cross-linking bonds. This value was estimated from the distribution of labeled fragments that resulted from the enzymatic digestion of PG and was confirmed by the analysis of free amino groups in [(3)H]DAP of intact PG. Although there were subtle, strain- and medium-dependent differences in percent cross-linking, these values varied only over a relatively narrow range (36 to 44%). The percent cross-linking of PG in the prototype strain, RD(5), grown in a standard gonococcal medium (LGCB(+)) was 41.0 +/- 2.0%. This is a relatively high degree of peptide cross-linking for a gram-negative bacterium. We also confirmed previous observations that the extent of PG cross-linking among isogenic gonococci was higher in strains, e.g., FA140 and FA136, carrying loci that govern increased resistance to multiple drugs.

Amino Acids↗