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Biomedical subjects

T Peterson

Publications and source records attributed to T Peterson.

12 recordsLinked to original sources
PubMed1992

Insertional mutagenesis of the maize P gene by intragenic transposition of Ac.

The P-rr allele of the maize P gene regulates the synthesis of pigments derived from flavan-4-ol in the pericarp, cob glumes and other floral organs. We characterized 21 P alleles derived by intragenic transposition of Ac from three known positions. Ac transpositions can occur in either direction in the P gene, and with no apparent minimum distance: in one case Ac transposed just 6 bp from its original insertion site. However, the distribution of transposed Ac elements was markedly nonrandom: of 19 transposed Ac elements derived from a single Ac donor, 15 were inserted in a 1.1-kb region at the 5' end of P, while none had inserted in an adjacent 3.2-kb intronic region. All of the Ac insertions affect both pericarp and cob glume pigmentation, providing further evidence that the P-rr allele contains a single gene required for both pericarp and cob glume pigmentation. The distribution of the inserted Ac elements and the phenotype conditioned by each allele suggests a structure of P-rr which is similar to that previously determined molecularly. Possible explanations for the nonrandom distribution of transposed Ac elements are discussed.

Base Sequence↗
PubMed1992

[Traumatic aneurysm of the hand--a rare complication of a stab injury].

This is a case report of a 22-year-old male who suffered a stab injury to his right hand. Sixteen days after primary wound closure, he complained of pain from a pulsating mass in his right palm, with numbness along the ulnar side of the middle finger. At operation, a false aneurysm was found and resected, after ligation of the common digital artery proximal and distal to the aneurysm.

Adult↗
PubMed1991

A possible hot spot for Ac insertion in the maize P gene.

We have analyzed the footprints left by a single Ac transposable element during its intragenic transposition to different positions in the maize P gene. One site appears to have been visited twice by transposons, indicating that it may be an insertion hot spot. Implications of this finding for the origin of the P-vv allele are discussed. Analysis of transposon footprints may prove generally useful for establishing pedigree relationships among gene alleles.

Alleles↗
PubMed1991

Ac induces homologous recombination at the maize P locus.

The maize P gene conditions red phlobaphene pigmentation to the pericarp and cob. Starting from two unstable P alleles which carry insertions of the transposable element Ac, we have derived 51 P null alleles; 47 of the 51 null alleles have a 17-kb deletion which removes the 4.5-kb Ac element and 12.5 kb of P sequences flanking both sides of Ac. The deletion endpoints lie within two 5.2-kb homologous direct repeats which flank the P gene. A P allele which contains the direct repeats, but does not have an Ac insertion between the direct repeats, shows very little sporophytic or gametophytic instability. The apparent frequency of sporophytic mutations was not increased when Ac was introduced in trans. Southern analysis of DNA prepared from the pericarp tissue demonstrates that the deletions can occur premeiotically, in the somatic cells during development of the pericarp. Evidence is presented that the deletions occurred by homologous recombination between the two direct repeats, and that the presence of an Ac element at the P locus is associated with the recombination/deletion. These results add another aspect to the spectrum of activities of Ac: the destabilization of flanking direct repeat sequences.

Alleles↗
PubMed1979

Agrobactin, a siderophore from Agrobacterium tumefaciens.

A siderophore (microbial iron transport compound) was isolated from low iron cultures of Agrobacterium tumefaciens B6. The substance was characterized as a threonyl peptide of spermidine acylated with 3 residues of 2,3-dihydroxybenzoic acid, the carbonyl group of 1 residue of the latter participating in an oxazoline ring with the beta-hydroxyl of the threonine moiety. The compound, N-[3-(2,3-dihydroxybenzamido)propyl]-N-[4-(2,3-dihydroxybenzamido)butyl]-2-(2,3-dihydroxyphenyl)-trans-5-methyl-oxazoline-4-carboxamide, was given the trivial name agrobactin. Exposure to acid opened the oxazoline ring to afford agrobactin A. Ferric agrobactin A and agrobactin A itself, but not agrobactin or its ferric complex, had some capacity to feed iron to enterobactin-deficient strains of Escherichia coli and Salmonella typhimurium. Agrobactin was produced by A. tumefaciens in response to iron deficiency and was able to reverse the iron starvation in this organism precipitated by the presence of a ferric complexing agent not utilized by the cells.

Biological Transport↗
PubMed1979

Ischemic myocardial injury after exercise stress in the pressure-overloaded heart.

Systemic hemodynamics and regional myocardial blood flows were determined in 18 miniswine during the development of pressure-overload hypertrophy induced by supravalvular aortic constriction. Nine miniswine served as control animals. Regional myocardial blood flows were measured at rest and during exercise stress with radioactive microspheres after 2 days and 1 month of aortic constriction. Exercise stress, causing the heart rate to increase to 85% of its maximum, was imposed twice weekly for 5 minutes on 13 pressure-overloaded animals to elicit differences between the control and experimental groups that might not occur at rest. At rest, regional myocardial blood flows of pressure-overloaded animals were similar to those of control animals. When exercise stress was imposed after 2 days and 1 month of pressure overload, endocardial blood flows decreased 45% below control exercise levels, although epicardial blood flows were unchanged. During the first 2 weeks of pressure overload epicardial and endocardial electrocardiograms showed S-T segment elevation with exercise stress but not at rest. Postmortem examinations after 1 month of pressure overload showed significant histologic evidence of myocardial injury, namely, fibrosis, which was subendocardially located. These findings indicate that the pressure-overloaded heart is at risk for ischemic injury, particularly during the early, uncompensated stage.

Animals↗
PubMed1978

Calcium, magnesium, phosphorus, copper, and manganese balance in adolescent females.

Calcium, magnesium, phosphorus, copper, and manganese balances were determined in 14 girls (12.5 to 14.5 years of age) during a 30-day period. Menus were composed of ordinary foods and were typical of subjects' usual dietary habits. The diets contained 1.07 g calcium, 193 mg magnesium, 0.85 g phosphorus, 2.8 mg copper, 3.0 mg manganese, and 7.4 or 13.4 mg zinc daily. Defatted soy was substituted for 0, 15, or 30% of the meat in lunch menus. Neither the alteration of dietary zinc levels or the partial substitution of soy for meat significantly affected retention of the five minerals. Retentions of calcium (r = 0.654), magnesium (r = 0.786), phosphorus (r = 0.560), copper (r - 0.805), and manganese (r = 0.855) by subjects were all significantly (P less than 0.001) correlated to retention of zinc. These correlations probably reflect the correlations between fecal losses of calcium (r = 0.438), magnesium (r = 0.434), phosphorus (r = 0.377), copper (r = 0.318), and manganese (r = 0.318) and the volume of feces. On these dietary regimes adolescents were in positive balances for calcium, phosphorus, and copper, but were in negative balances for magnesium and managenese.

Adolescent↗
PubMed1978

Motorized minitrack for exercising large animals.

A simply constructed device for exercise training large animals, e.g., swine, is described. Basically the device is a small, circular, enclosed track constructed of plywood and metal fence material. A centrally located, vertical shaft powered by a DC motor rotates at a variable speed. Attached to each of four horizontal metal beams extending from the shaft are four suspended partitions which hang freely above the enclosed track surface. As the shaft rotates, the four partitions move in unison, thus forcing animals in each compartment to move at the same pace. The advantages of this device are its cost, low maintenance, and the flexibility to train eight animals by one person. Preliminary results of a study on training pigs are discussed.

Animals↗
PubMed1977

Renal amyloidosis in KK mice that may be misinterpreted as diabetic glomerulosclerosis.

A normoglycemic, normoinsulinemic, "lean" phenotype KK mouse having a morphologically normal pancreatic islet had renal lesions reminiscent of diabetic glomerulosclerosis described in the literature for KK mice. Most of these animals also had splenomegaly. Using histochemical and ultrastructural methods, the renal and splenic lesions were demonstrated to be amyloidotic. Extensive deposits of amyloid were found in the liver and adrenals. Amyloidosis was found in all lean KK mice 4 months of age or older and in five of 11 C57BL/6J mice over 1 year of age. The validity of data attributing glomerulosclerosis to diabetes in mice that are neither glucosuric nor hyperglycemic or that show normal tolerance to glucose load should be questioned until amyloidosis is ruled out.

Amyloidosis↗
PubMed1976

A microsurgical technique for orthotopic ovarian transplantation in the Chinese hamster.

A microscopic surgical technique for the orthotopic transplantation of ovaries in the Chinese hamster is described. The procedure, which uses microcauterization of the mesovarian stump and closure of the ovarian bursa with microvascular suture, resulted in a 75 to 80 percent surgical success rate in a series of 12 nondiabetic and 12 diabetic hamsters. Applications include the production of prediabetic offspring, the study of intrauterine environmental effects on transplant-derived offspring, and the preservation of endangered genetic colony sublines.

Animals↗