Oxygen binding by single crystals of hemoglobin: the problem of cooperativity and inequivalence of alpha and beta subunits.

Oxygen binding by the human hemoglobin tetramer in the T quaternary structure is apparently noncooperative in the crystalline state (Hill n = 1.0), as predicted by the two-state allosteric model of Monod, Wyman, and Changeux (MWC) (Mozzarelli et al., Nature 351:416-419, 1991; Rivetti et al.

A Feldmannia algal virus has two genome size-classes.

Persistent viruses occur intracellularly in brown algae, specifically the Ectocarpales, and as reported here in the genus Feldmannia. Feldmannia species are small (1 mm-several cm), filamentous forms with single-celled meiotic sporangia that normally produce haploid zoospores. In the isolate reported here, spores were not observed in the sporangia but rather numerous (approximately 10(6) per cell) polyhedral viruses are formed in their place.

A brown algal virus genome contains a "RING" zinc finger motif.

The brown filamentous alga Feldmannia sp. contains a large icosahedral dsDNA virus, FsV, of which there are multiple variants. A 4.

The Effect of Urinary pH and Flow Rate on the Renal Elimination of Zopolrestat and Zopolrestat Glucuronide in Humans.

Zopolrestat is an aldose reductase inhibitor that may be useful in the treatment of diabetic complications by reducing flux through the polyol pathway. The plasma half-life of zopolrestat in man is approximately 30 h, and approximately 45% of an orally administered 1000-mg dose is eliminated in the urine as unchanged drug. Because active secretion accounts for much of the renal clearance for zopolrestat, a carboxylic acid with a pK(a) of 5.

Induction of CYP1A1 and ALDH-3 in lymphoid tissues from Fisher 344 rats exposed to 2,3,7,8-tetrachlorodibenzodioxin (TCDD).

The immune system is a primary target for toxic insult by a number of drugs and environmental chemicals, many of which require activation to toxic metabolites by drug-metabolizing enzymes. We compared the induction of drug-metabolizing enzymes, including cytochrome P450 1A1 (CYP1A1) and aldehyde dehydrogenase (ALDH), in lymphoid tissues of F344 rats following treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). ALDH was induced in both the spleen and the thymus after TCDD treatment, with maximal expression at 9 and 15 days, respectively.

Characterization of a repetitive DNA element in a brown algal virus.

We describe a family of repetitive sequences found in viruses infecting the brown alga Feldmannia sp. Previously we have demonstrated that the dsDNA genomes of viruses infecting one Feldmannia sp. isolate exist as two size classes of 160 and 179 kb.

Synthesis and structure-activity relationships of stilbene retinoid analogs substituted with heteroaromatic carboxylic acids.

Retinoids elicit biological responses by activating a series of nuclear receptors. Six retinoid receptors belonging to two families are currently known: retinoic acid receptors (RAR alpha,beta,and gamma) and retinoid X receptors (RXR alpha,beta,and gamma). Stilbene retinoid analogs of retinoic acid (RA), such as (E)-4-[2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)prope n-1- yl]benzoic acid (TTNPB, 1) and (E)-4-[2-(5,6,7,8-tetrahydro-3,5,5,8,8-pentamethyl-2-naphthalenyl)pro pen-1- yl]benzoic acid (3-methyl-TTNPB, 2), display differential RAR and RXR activities, depending on the substituent at C3 of the naphthalene ring.

Public understanding of medical screening.

Aim: To estimate the extent of public understanding of mass screening for disease and of the benefits and limitations of screening.

Methods: Telephone interviews were conducted with a national sample of 835 Australians.

Results: Of total respondents, 68% claimed to have heard of screening tests, but only 21% correctly understood that screening tests are for asymptomatic people.

Purification to homogeneity of the heteromeric DNA-binding form of the aryl hydrocarbon receptor from rat liver.

The aryl hydrocarbon receptor (AhR) is a transcriptional enhancer that is activated by the binding of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related toxic xenobiotics, as well as some naturally occurring compounds. Ligand binding initiates 1) dissociation of the ligand-bound monomeric AhR from the ligand-unoccupied multimeric complex and 2) biochemical and/or conformational changes that enable association of the ligand-bound monomer with other proteins. This heteromeric complex has high affinity for specific elements [dioxin-responsive elements (DREs)] in the regulatory regions of a number of structural genes, the induction and/or repression of which may be a mechanism of toxicity of TCDD.