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Biomedical subjects

A Wright

Publications and source records attributed to A Wright.

At least 397 records · Page 22Linked to original sources
PubMed1970

Differences between the biliary excretion of tri [14C] methyl-(3-hydroxy-phenyl) ammonium iodide in Wistar and Gunn rats.

1. The biliary excretion of [(14)C]trimophonium iodide [tri[(14)C]methyl(3-hydroxyphenyl)ammonium iodide] was studied in normal Wistar animals and in jaundiced homozygous Gunn rats. 2. In normal Wistar rats small amounts of radioactivity (approx. 3% of the dose in 4h) were excreted in bile as two glucuronide conjugates, i.e. [(14)C]trimophonium glucuronide [tri[(14)C]methyl-(3-oxyphenyl)ammonium glucuronide] (85%) and 3-di[(14)C]methylaminophenyl glucuronide (10-15%). Only minor amounts of the unchanged drug were detected in bile. 3. In the homozygous jaundiced Gunn rat large amounts of radioactivity (26% of the dose in 4h) were eliminated in bile as [(14)C]trimophonium glucuronide alone. The quantitative excretion of this metabolite in Gunn rat bile was about ten times that in normal animals. 4. It is proposed that the biochemical lesion in the homozygous Gunn rat may indirectly affect the biliary transport of exogenous glucuronides across the canalicular membrane.

Animals↗
PubMed1970

Mechanism of polymerization of the Salmonella O-antigen: utilization of lipid-linked intermediates.

Cell envelope fractions from Salmonella can utilize exogenous lipid-linked intermediates for the synthesis of polymeric O-antigen. We describe a method for preparing aqueous suspensions of lipid intermediates and show that freezing and thawing of cell envelope-lipid intermediate mixtures is required for efficient synthesis. The lipid intermediates move freely in the hydrophobic environment of the membrane.

Antigens↗
PubMed1967

Direction of chain growth in polysaccharide synthesis.

The biosynthesis of a bacterial polysaccharide-the surface O-antigen of Salmonella newington-differs in several respects from the more classical example of glycogen synthesis. Sugars are not transferred directly to the antigen from sugar nucleotide precursors but are transferred first into lipid-linked oligosaccharides. Growth of the polysaccharide chain then occurs by assembly of these lipid-linked precursors at the reducing end of the polymer rather than at its nonreducing end as in glycogen. This method of assembly, in which nascent chains are transferred to the next subunit, is analogous to the growth of proteins or fatty acids. It seems possible that these differences reflect the more complex requirements of a surface polysaccharide synthesized by membrane-bound enzymes. If this is the case, then several other polysaccharide systems may be synthesized by comparable mechanisms.

Antigens↗
PubMedDate not supplied

Absorption of alpha-MSH from subcutaneous and intraperitoneal sites in the rat.

Pentobarbitone anesthetized rats were injected with 30 nmol (50 micrograms) alpha-MSH administered intraperitoneally (IP) and subcutaneously (SC) in an acid-saline vehicle, or SC in a zinc phosphate vehicle. Concentrations of alpha-MSH in plasma were measured by radioimmunoassay. The pharmacokinetic parameters for the three modes of administration were determined by fitting a one-compartment open model to the plasma level data. The t1/2 for absorption using the saline vehicle was 7.3 and 5.6 min from the IP and SC sites, respectively. The t1/2 for absorption from the zinc phosphate complex of 17.7 min was significantly longer. Five percent of the IP dose was absorbed into the systemic circulation giving a peak plasma level of 14.1 nmol/l. The absorption of 2-3 percent was significantly lower following SC administration; peak plasma levels were 8.3 and 4.8 nmol/l for the saline and zinc phosphate vehicles, respectively. The low percentage absorption values indicated a high degree of metabolism of the peptide by peripheral tissues on its passage from the injection sites into the circulation.

Animals↗
PubMedDate not supplied

Effects of low-dose heparin on failure of intravenous infusions in children.

OBJECTIVE: To determine if a dextrose-saline solution manufactured under commercial conditions and containing 1 IU per ml of heparin prolongs the use of infusion sites in children. DESIGN: Double-blind randomized trial. PATIENTS: Eighty children in a medical ward. OUTCOME MEASURES: Failure of infusion sites from phlebitis and/or extravasation. INTERVENTION: Duration of use of infusion sites was calculated to the nearest hour. STATISTICS: Univariate survival analysis. RESULTS: The median time to failure when solutions contained the heparin (97 hours) was significantly increased (p < 0.0001) compared with control solutions (43 hours). CONCLUSIONS: Use of solutions containing low-dose heparin is recommended for children who might have problems with venous access.

Catheters, Indwelling↗
PubMedDate not supplied

Lipomatous hypertrophy of the interatrial septum: characterization by transesophageal and transthoracic echocardiography, magnetic resonance imaging, and computed tomography.

Lipomatous hypertrophy of the interatrial septum is a benign condition that must be distinguished from other space-occupying lesions of the atria. Patients with this disorder generally have chronic pulmonary disease and thus are difficult to image with conventional transthoracic two-dimensional echocardiography. Transesophageal echocardiography can provide high quality imaging of intracardiac structures in patients who lack adequate transthoracic echocardiographic windows as a result of pulmonary disease. This case report describes the appearance of lipomatous hypertrophy of the interatrial septum as investigated by transesophageal echocardiography.

Aged↗
PubMedDate not supplied

DNA segregation: putting chromosomes in their place.

Recent studies provide evidence that bacterial chromosomes are replicated by an enzyme factory, the replisome, located at a fixed position at the center of the cell; the fixed replisome could be a major factor in determining chromosome order in the cell, and may provide the force that drives chromosome segregation.

Bacteria↗
PubMedDate not supplied

Comparison of moving-strip therapy using a Cobalt-60 teletherapy unit, a Varian 4-MV linear accelerator, and a Varian 10-MV linear accelerator.

Cobalt-60 gamma rays and 4- and 10-MV x rays are compared for moving-strip therapy in terms of the dose uniformity and the given dose needed to deliver a prescribed tumor dose. Dose distributions in phantoms of 14--32-cm thickness were calculated for each therapy unit. Individual given doses which would deliver the most uniform dose along the midline of the treatment volume were determined by computer and were verified experimentally by thermoluminescent dosimetry. Using computer optimization techniques, the midplane dose uniformity is improved significantly for the three therapy units considered.

Cobalt Radioisotopes↗