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Biomedical subjects

J D Jones

Publications and source records attributed to J D Jones.

At least 145 records · Page 8Linked to original sources
PubMed1989

Spontaneous phosphatidylcholine transfer by collision between vesicles at high lipid concentration.

The transfer kinetics of [3H]-1-palmitoyl-2-oleoylphosphatidylcholine ([3H]POPC) and 1-palmitoyl-2-(pyrenyldecanoyl)phosphatidylcholine (PyrPC) from POPC small unilamellar vesicles were examined at 37 degrees C with lipid concentrations ranging from 0.1 to 40 mM. The rate of [3H]POPC transfer was determined by analyzing the movement of this lipid from charged donor to neutral acceptor vesicles. The rate of decay of the ratio of the intensity of pyrene excimer fluorescence to that from the pyrene monomer (E/M) upon addition of an unlabeled vesicle population to a population containing PyrPC was used to evaluate PyrPC transfer. For both lipids, the kinetic data are best described by a model which assumes that transfer occurs by vesicle collisions as well as by desorption from the bilayer. For [3H]POPC, the off-rate constant is 0.014 h-1 while the collisional rate constant is 0.0016 mM-1 h-1. PyrPC has an off-rate constant of 0.023 h-1 and a collisional constant of 0.0015 mM-1 h-1. These numbers were calculated by assuming the rate of interbilayer transfer to be negligible relative to that of intervesicular transfer. The large transfer fluxes in the high vesicle concentration range where the collisional process dominates suggest that spontaneous transfer may be of importance in membrane biogenesis.

Kinetics↗
PubMed1989

Epiretinal membranes and cystoid macular edema in gyrate atrophy of the choroid and retina.

A 26-year-old woman with gyrate atrophy of the choroid and retina and hyperornithinemia lost central visual acuity because of cystoid macular edema associated with epiretinal membrane formation. Dietary manipulation over a 5-month interval reduced the plasma ornithine levels 37% but did not halt the progression of the gyrate atrophy nor influence the cystoid edema or visual acuity.

Adult↗
PubMed1989

Effect of dietary fibers on glycemia and insulinemia and on gastrointestinal function in rats.

The effects of purified and semipurified dietary fiber supplements on glycemia and insulinemia were measured simultaneously with their effects on digestive tract function in the rat. An insoluble fiber (cellulose) and four soluble fibers (guar gum, carboxymethylcellulose, mustard mucilage, and oat beta-glucan) were added separately to a fiber-free solid diet and fed to Sprague-Dawley rats for 10 days. Guar gum and oat beta-glucan reduced the food intake, whereas cellulose increased it. Guar gum reduced weight gain. Cellulose increased the protein efficiency ratio. After a 13-h fast, glycemia and insulinemia were measured 45, 90, 210, and 360 min after the beginning of a voluntary short meal. Addition of fibers did not change the glycemic response, but soluble fibers significantly decreased insulinemia 45 min after the meal. All fibers significantly delayed gastric emptying, cellulose and mustard mucilage being the most effective. Dry matter contents of the small intestine were increased especially by guar gum and oat beta-glucan. All fibers seemed to slow down small intestinal transit and decreased intestinal absorption. In the present experimental situation, both gastric and intestinal components played a role in the hypoinsulinic effect of dietary fibers. The intestinal component appeared to be more determinant for all soluble fibers, except mustard mucilage where the gastric component was more important.

Animals↗
PubMed1989

Plasma dopa and feeding.

Dopa is a normal constituent of plasma in man and experimental animals. Dopa concentrations in plasma have been used to reflect the activity of tyrosine hydroxylase, the rate-limiting enzyme in the synthesis of catecholamines. However, it is not known to what extent plasma dopa is affected by feeding, since several foods contain dopa or tyrosine, the immediate precursor of dopa. In this study dopa and its major metabolites (3-O-methyldopa and free and conjugated catecholamines) were measured in plasma of dogs during 5 hr after feeding. Plasma dopa did not change significantly after feeding. This finding increases the value of plasma dopa as an index of tyrosine hydroxylase activity. Plasma norepinephrine decreased, and conjugated dopamine increased, after feeding; the other analytes did not change significantly.

Animal Feed↗
PubMed1989

Pyroglutamic acidemia in an adult patient.

Pyroglutamic acidemia, a rare metabolic disorder, usually appears in infancy. It is characterized by retardation, ataxia, hemolytic anemia, and chronic acidosis and is caused by a marked deficiency of glutathione synthetase (EC 6.3.2.3) activity. This disease is inherited as an autosomal recessive trait, but the clinical condition is also detected in heterozygotes. We report an unusual case of high-anion-gap metabolic acidosis in a 52-year-old woman who was admitted with neurological complaints and breathing problems but without the characteristic clinical features of congenital glutathione synthetase deficiency. The etiology of the acidosis could not be attributed to ketoacidosis, lactic acidosis, or ingestion of methanol, salicylate, or ethylene glycol. Analysis of the patient's plasma and urine for organic acids revealed the presence of high concentrations of pyroglutamate (5-oxoproline), which remained high throughout her hospitalization.

Acidosis↗
PubMed1988

Relative strengths of the 35S cauliflower mosaic virus, 1', 2', and nopaline synthase promoters in transformed tobacco sugarbeet and oilseed rape callus tissue.

The 35S promoter of cauliflower mosaic virus and promoters from the nopaline synthase, 1' and 2' genes of Agrobacterium tumefaciens T-DNA were fused to the bacterial octopine synthase and chitinase gene coding regions. These chimaeric gene constructions were introduced into tobacco, sugarbeet and oilseed rape cells and their relative levels of expression measured by primer extension analysis of RNA isolated from pooled populations of stably transformed calli. In tobacco callus, the 35S promoter provided the highest levels of gene expression, followed by the 2', 1' and nopaline synthase promoters. While the ranking of these promoters is conserved in sugarbeet and oilseed rape callus, there is between-species variation in the relative strength of these promoters. In all three species, transcription initiation is conserved for each of the chimaeric gene constructions. Additional constructions in which the 5' untranslated leader of a petunia chlorophyll a/b binding protein gene is substituted for DNA downstream of the 35S transcription start site demonstrates that heterologous 5' leader sequences can be utilized to augment steady-state levels of reporter gene expression.

Amino Acid Oxidoreductases↗
PubMed1988

Improved expression of streptomycin resistance in plants due to a deletion in the streptomycin phosphotransferase coding sequence.

Previous studies have shown that a chimeric streptomycin phosphotransferase (SPT) gene can function as a dominant marker for plant cell transformation. The SPT marker previously described by Jones and co-workers has a limited value since it conferred a useful level of resistance only to a fraction (10%) of Nicotiana plumbaginifolia transgenic lines. Expression of resistance was species specific: no such resistant transformants were found in N. tabacum. In this paper we describe an improved SPT construct that utilizes a mutant Tn5 SPT gene. The mutant gene, SPT*, encodes a protein with a two amino acid deletion close to its COOH-terminus. In N. tabacum cell culture the efficiency of transformation with the improved streptomycin resistance marker was comparable to kanamycin resistance. When the chimeric SPT* gene was introduced linked to a kanamycin resistance gene, streptomycin resistance was expressed in most of the transgenic N. tabacum lines.

Chimera↗
PubMed1988

Concentration effect of soluble dietary fibers on postprandial glucose and insulin in the rat.

The effects of different soluble fibers on blood glucose and insulin responses to voluntary meals in the rat were investigated. Rats (165-180 g) were adapted for 2 weeks to a fiber-free control diet or fiber diets made by dilution of the fiber-free diet with the fiber. Fibers and concentrations used were carboxymethylcellulose (1.25, 2.5, and 5%), guar gum, oat beta-glucan (2.5, 5, and 7.5%), and mustard mucilage (5, 10, and 15%) as the soluble fibers, and cellulose (20%) as the insoluble fiber. Meal challenges (0.75 g/100 g body weight offered for consumption within a period of 15 min) were made with the adaptation diet. Soluble fibers reduced food intake and growth with a concentration effect, while cellulose increased food intake. All fibers reduced dry matter and nitrogen digestibilities but had no effect on the protein efficiency ratio. Only carboxymethylcellulose (at 5%) reduced postprandial glycemia at 30 min (p less than 0.05). Cellulose had no effect on plasma insulin which was markedly reduced with a concentration effect by all soluble fibers (except mustard mucilage) in the following decreasing order: carboxymethylcellulose, guar gum, beta-glucan, and mustard mucilage. The effect of fibers seemed closely related to the viscosity of fiber solutions in the presence of the diet ingredients. The present findings demonstrate the positive effect of fibers on postprandial insulinemia but with only a slight effect on glycemia. They indicate that the physicochemical interaction of the fibers with other dietary ingredients is important.

Animals↗
PubMed1987

Parotid lipoblastoma in an infant.

We report a case of 'matured' lipoblastoma occurring within the parotid gland of a 7-month-old male. This benign fatty tumor is considered to represent localized continuation of fetal fat development into the post-birth period. At least 7 cases have been reported in the head and neck region, but this is the first known occurrence within a salivary gland.

Humans↗
PubMed1987

An efficient mobilizable cosmid vector, pRK7813, and its use in a rapid method for marker exchange in Pseudomonas fluorescens strain HV37a.

We describe the construction and utilization of a new mobilizable cosmid vector. Using this vector, mobilizable libraries of bacterial DNA can be efficiently made without a need for size fractionation of target DNA. The low stability of this vector in Pseudomonas fluorescens makes it useful in a rapid strategy, which is not dependent on plasmid incompatibility, for recombining transposon-induced mutations into the bacterial chromosome.

Cosmids↗
PubMed1987

Childhood scoliosis: MR imaging.

The spinal cords of 28 scoliosis patients between the ages of 1 month and 17 years were examined with magnetic resonance (MR) imaging. Complete visualization was obtained in all cases. In 15 patients (53%) neuropathologic abnormalities demonstrated by MR imaging significantly affected their clinical course, including tethered cords (n = 7), syringomyelia (n = 5), Arnold-Chiari I malformation (n = 4), spinal cord tumors (n = 2), Arnold-Chiari II malformation (n = 3), and diastematomyelia (n = 1). The advantages of MR imaging in the evaluation of the scoliotic spine in children include a high sensitivity for the occult conditions associated with scoliosis, good anatomic demonstration of the cord, and absence of bone artifacts. MR imaging is recommended as a primary imaging modality in scoliosis, following conventional radiography.

Arnold-Chiari Malformation↗
PubMed1986

Significance of serum protein and lipid-bound sialic acid as a marker for genitourinary malignancies.

A prospective study was done to evaluate the roles of serum N-acetylneuraminic acid (NANA) and the lipid-bound subfraction of sialic acid (LSA) concentrations in the detection and staging of cancer, and the follow-up of treatment in patients with genitourinary malignancies. Multiple determinations were obtained in 177 subjects: 90 normal volunteers, 38 patients with prostate cancer, 20 patients with bladder cancer, 15 patients with renal cell cancer, and 14 patients with benign urologic diseases. The results showed a low incidence of elevated values in patients with early stages of cancer and a high incidence of false-positive values with serum NANA concentrations in patients with benign urologic diseases, especially prostatitis. Serum NANA and LSA concentrations were highly correlated with the stage and grade in patients with advanced urologic cancer, and may be used as markers of tumor activity during follow-up under treatment; currently, however, they are not useful in the screening of patients for urologic cancer. Their usefulness in prostatic cancer is at least comparable to that of acid phosphatase determinations by the enzymatic and radioimmunoassay methods, which were elevated in a smaller percentage of patients with prostate cancer than were the NANA or LSA concentrations.

Adult↗
PubMed1986

Isolation and characterization of genes encoding two chitinase enzymes from Serratia marcescens.

Analysis of clones isolated from a cosmid DNA library indicates that the Serratia marcescens chromosome contains at least two genes, chiA and chiB, which encode distinct secreted forms of the enzyme chitinase. These genes have been characterized by inspection of chitinase activity and secreted proteins in Escherichia coli strains containing subclones of these cosmids. The two chitinase genes show no detectable homology to each other. DNA sequence analysis of one of the genes predicts an amino acid sequence with an N-terminal signal peptide typical of genes encoding secreted bacterial proteins. This gene was mutagenized by cloning a neomycin phosphotransferase gene within its coding region, and the insertion mutation was recombined into the parental S. marcescens strain. The resulting chiA mutant transconjugant showed reduced chitinase production, reduced inhibition of fungal spore germination and reduced biological control of a fungal plant pathogen.

Journal Article↗
PubMed1986

Painless giant cell thyroiditis diagnosed by fine needle aspiration and associated with intense thyroidal uptake of gallium.

A 52-year-old woman presented with fever, goiter, and no evidence of pain or tenderness in the thyroid. A diagnosis of silent thyroiditis was made after obtaining evidence of biochemical thyrotoxicosis, intense gallium-67 citrate thyroidal localization, and cytologic thyroiditis. Fine needle aspiration biopsy of the thyroid revealed numerous giant cells in all areas of the thyroid, typical of subacute thyroiditis. This is believed to be the first time painless thyroiditis is reported with the classic cytologic feature of painful subacute thyroiditis.

Biopsy, Needle↗