Search PubMed⌕ Search

Biomedical subjects

R R Reed

Publications and source records attributed to R R Reed.

At least 91 records · Page 5Linked to original sources
PubMed1983

Retrospective analysis of surgically treated Le Fort fractures.

Craniofacial suspension, in conjunction with intermaxillary fixation (IMF), is the time-honored method of Le Fort fracture repair. However, several patients with maxillary fractures treated at the Medical Center Hospital of Vermont in Burlington by the oral surgery and otolaryngology services have been managed with IMF alone. Twenty-one of these patients were examined retrospectively through comprehensive dental and otolaryngologic clinical analyses. Traditional concerns for facial elongation and nonunion were among the key questions addressed by this study. There was no evidence of nonunion in any patient examined. A comparison of each patient's lateral cephalometric roentgenogram with computerized norms suggested that facial elongation did not occur when IMF alone was the principal method of repair.

Adolescent↗
PubMed1982

Transposon-mediated site-specific recombination: identification of three binding sites for resolvase at the res sites of gamma delta and Tn3.

The tnpR gene product, resolvase, of the transposable element gamma delta mediates site-specific recombination between two copies of gamma delta directly repeated on the same replicon, and it negatively regulates transcription of the tnpA (transposase) gene and its own gene. The recombinational site, res, and the regulatory region both are located in the tnpA-tnpR intercistronic region. In studying the interaction of purified resolvase with DNA fragments derived from gamma delta and the related transposon, Tn3, that span this region, we have demonstrated that three sites specifically bind resolvase. Site I overlaps the recombinational crossover point and both transcriptional promoters. Sites II and III cover most of the DNA between the crossover point and the translational start of the tnpR gene. These are the only binding sites we have detected in a region of about 400 base pairs centered on the crossover point. Studies of cointegrates that contain only part of the region that binds resolvase indicate that site I is not sufficient for efficient site-specific recombination and suggest that all three sites are probably required.

Binding Sites↗
PubMed1981

Transposon-mediated site-specific recombination: a defined in vitro system.

Transposition of the insertion element gamma delta is thought to involve formation of intermediates in which the element is present at each junction between donor and target replicons. In vivo these cointegrate structures are rapidly converted to the end products of transposition by site-specific recombination at a defined sequence, res, that is present in each directly repeated gamma delta element. Resolvase, an element encoded protein of molecular weight 21,000 is required for cointegrate resolution. I have demonstrated site-specific recombination in vitro using purified resolvase and a cointegrate analog substrate. The required components of the system described here are resolvase, negatively supercoiled substrate DNA, buffer and Mg2+. Neither host-encoded products nor high energy cofactors appear to be required for resolution in vitro. Catenated, resolved molecules are the major products of the reaction. Elimination of Mg2+ from the reaction yields different product molecules. The in vitro system described here provides an opportunity for detailed study of the resolution reaction.

Bacterial Proteins↗
PubMed1981

Transposon-mediated site-specific recombination in vitro: DNA cleavage and protein-DNA linkage at the recombination site.

Resolvase, the product of the tnpR gene of the transposable element gamma delta, mediates a site-specific recombination between two copies of the element directly repeated on the same replicon. The resolution site, res, at which resolvase acts lies in the intercistronic region between the tnpA and tnpR genes. We have studied this site-specific recombination in vitro. In the absence of Mg2+, a resolvase-res complex is formed, which contains DNA molecules that have been cleaved at res. Our data suggest that in this complex resolvase is covalently attached to the 5' ends of the cleaved DNA, leaving free 3' hydroxyl groups. DNA cleavage is stimulated by the interaction of two res sites on the same substrate molecule and appears to be an intermediate step in normal res site recombination. We show that the DNA is cut within a region previously identified as containing the crossover point at the palindromic sequence 5'- (see formula in text) to generate 3' extensions of two bases.

Bacterial Proteins↗
PubMed1981

Resolution of cointegrates between transposons gamma delta and Tn3 defines the recombination site.

Transposition of the genetically related insertion elements gamma delta and Tn3 is thought to involve two steps. In the case of transposition from one replicon to another, the first step is fusion of the parent and target replicons with the element appearing in direct orientation at the two junctions. In a subsequent reaction, the cointegrate structure is resolved via a site-specific recombination event. I have constructed two plasmids, each carrying segments of gamma delta and Tn3, that contain the internal resolution site. The tnpR gene product encoded by either Tn3 or gamma delta mediates intramolecular recombination between these two sites. The product of this recombination is a hybrid region that contains gamma delta and Tn3 sequences fused at the point of crossover. DNA sequence analysis of such recombinants indicates that the recombination occurs within a 19-base-pair (bp) region of exact homology between gamma delta and Tn3. The site lies in the 160-bp center intercistronic region, 50 bp before the beginning of the tnpA gene. My results therefore suggest a model for the coupled regulation of the repressor (tnpR) and the transposase (tnpA) genes and site-specific recombination of transposition intermediates. The Tn3/gamma delta recombination system and bacteriophage lambda integration are compared.

Bacteriophage lambda↗
PubMed1979

Transposition of the Escherichia coli insertion element gamma generates a five-base-pair repeat.

We have determined DNA sequences surrounding the termini of the Escherichia coli insertion element gamma delta, both at its normal locus on the F (fertility) factor and at three different sites of insertion into the plasmid pBR322. After transposition, a five-base-pair pBR322 sequence is duplicated and appears in direct orientation adjacent to each end of the element. No such duplication flanks the ends of gamma delta in F, and there is no apparent homology between the sequences surrounding gamma delta in F and the five-base-pair duplications generated by insertion. These findings suggest that the duplications are not essential for transposition and that they do not act to direct gamma delta to a homologous site in the target chromosome. In addition, we find that the 35-base-pair inverted repeat that comprises the termini of gamma delta is strikingly similar in sequence to the ends of both the ampicillin-resistance transposon Tn3 and a 200-nucleotide-long sequence on the plasmid pSC101 which has been shown to mediate recombination with phage f1 replicative form. Within the terminal region, there is a specific heptanucleotide sequence common to each of the above elements and to bacteriophage Mu, all of which generate five-base-pair repeats upon insertion.

Base Sequence↗
PubMed1978

Radical cystectomy for bladder cancer.

We reviewed 52 consecutive patients who had undergone radical cystectomy for bladder cancer prior to 1962 and have been followed for 15 to 23 years. The over-all survival rates at 5, 10 and 15 years were 38, 27 and 17%. Pathologic staging was the most important prognostic factor in the series.

Adult↗
PubMed1977

Acute renal vein thrombosis with dextran treatment.

The case of a 35-year-old woman with active ulcerative colitis and acute left renal vein thrombosis is presented. The successful management of this patient with dextran-70 is contrasted with other modes of therapy used currently.

Acute Disease↗
PubMed1977

An animal model for the growth of human tumor cell lines.

Newborn rats were thymectomized at less than 24 hr of age and received antilymphocyte serum and heterologous human tumor cells. This model allows the growth of large primary tumors with a high metastatic percentage. This model may be applicable to the study of a wide variety of genitourinary tumors.

Animals↗
PubMed1976

Testis tumor metastatic to lung: twenty-two-year survivor.

A case is presented of a twenty-two-year survivor following pulmonary resection of a solitary embryonal cell carcinoma metastasis from a primary teratocarcinoma of the testis. The literature is reviewed with regard to this problem, and the criteria for pulmonary resection of metastic lesions are presented.

Adult↗
PubMed1971

Induced seizures as therapy of experimental strokes in dogs.

Intracerebral pO2, as measured in normal dog brains by a modified mass spectrometer, was found to increase following seizure activity and remain elevated at least 2 hours. These results were found with both drug- and electrically-induced seizures. The pO2 increased to a greater degree in brain tissue rendered ischemic by middle cerebral artery occlusion. A transient reflex hypertension was observed with seizure activity, but hypertension alone failed to produce significant pO2 changes. Since oxidative metabolism has been shown by other investigators to proceed at an elevated rate during seizure activity, the increased pO2 must reflect improved collateral circulation following seizure activity.

Animals↗