A hyperthermophilic plant-type [2Fe-2S] ferredoxin from Aquifex aeolicus is stabilized by a disulfide bond.

A [2Fe-2S] ferredoxin (Fd1) from the hyperthermophilic bacterium Aquifex aeolicus has been obtained by heterologous expression of the encoding gene in Escherichia coli. Sequence comparisons show that this protein belongs to the extended family of plant- and mammalian-type [2Fe-2S] ferredoxins but also indicate that it is not closely similar to either the plant-type or mammalian-type subfamilies. Instead, it appears to bear some similarity to novel members of this family, in particular the Isc-type ferredoxins involved in the assembly of iron-sulfur clusters in vivo.

Heterodisulfide reductase from Methanothermobacter marburgensis contains an active-site [4Fe-4S] cluster that is directly involved in mediating heterodisulfide reduction.

Heterodisulfide reductases (HDRs) from methanogenic archaea are iron-sulfur flavoproteins or hemoproteins that catalyze the reversible reduction of the heterodisulfide (CoM-S-S-CoB) of the methanogenic thiol coenzymes, coenzyme M (CoM-SH) and coenzyme B (CoB-SH). In this work, the ground- and excited-state electronic properties of the paramagnetic Fe-S clusters in Methanothermobacter marburgensis HDR have been characterized using the combination of electron paramagnetic resonance and variable-temperature magnetic circular dichroism spectroscopies. The results confirm multiple S=1/2 [4Fe-4S](+) clusters in dithionite-reduced HDR and reveal spectroscopically distinct S=1/2 [4Fe-4S](3+) clusters in oxidized HDR samples treated separately with the CoM-SH and CoB-SH cosubstrates.

Spectroscopic studies of Pyrococcus furiosus superoxide reductase: implications for active-site structures and the catalytic mechanism.

The combination of UV/visible/NIR absorption, CD and variable-temperature magnetic circular dichroism (VTMCD), EPR, and X-ray absorption (XAS) spectroscopies has been used to investigate the electronic and structural properties of the oxidized and reduced forms of Pyrococcus furiosus superoxide reductase (SOR) as a function of pH and exogenous ligand binding. XAS shows that the mononuclear ferric center in the oxidized enzyme is very susceptible to photoreduction in the X-ray beam. This observation facilitates interpretation of ground- and excited-state electronic properties and the EXAFS results for the oxidized enzyme in terms of the published X-ray crystallographic data (Yeh, A.

Photochemical generation and absolute reactivity of an allene oxide in solution.

A method for the rapid photochemical generation of allene oxides is described that allows absolute rate constants for the reactions of these interesting reactive intermediates to be measured. The fluorenylideneallene oxide generated using this method was found to rearrange to the corresponding cyclopropanone with a rate constant of 0.0012 s(-1) in TFE.

Intra- and interstrain differences in models of "behavioral despair".

In the present studies, base line and drug-induced performance of two mouse strains (C57Bl/6 and NIH-Swiss) was evaluated in the forced swim test (FST) and tail suspension test (TST). Intra- and interstrain comparisons indicate that the biological substrates mediating performance in these behavioral procedures are not identical. For example, in NIH-Swiss mice, a sevenfold difference in base line immobility was observed between the FST and TST.

Overseas recruitment.

Recruiting nurses from overseas can be a solution for the acute staffing shortages experienced by nursing homes. But before accepting nursing home contracts, it is really important that they have a clear understanding of the values and skills required to work with older people and of the unique and privileged role that nurses fulfil in these settings.

Common phytochemicals are ecdysteroid agonists and antagonists: a possible evolutionary link between vertebrate and invertebrate steroid hormones.

Many plant compounds are able to modulate growth and reproduction of herbivores by directly interacting with steroid hormone systems. In insects, several classes of phytochemicals, including the phytoestrogens, interfere with molting and reproduction. We investigated whether the anti-ecdysone activity may be due to interaction with the ecdysone receptor (EcR) using a reporter-gene assay and a cell differentiation assay of an ecdysone-responsive cell line, Cl.

Time sequence of the inhibition of endothelial adhesion molecule expression by reconstituted high density lipoproteins.

We have used discoidal reconstituted high density lipoproteins (rHDL) containing apolipoprotein (apo) A-I and dimyristoyl phosphatidylcholine (DMPC) as a tool to investigate the time sequence of the HDL-mediated inhibition of vascular cell adhesion molecule (VCAM)-1 and E-selectin expression in cytokine-activated human umbilical vein endothelial cells (HUVECs). Specifically, we have asked a few questions - (i) how long do the cells need to be exposed to the rHDL before adhesion molecule expression is inhibited and (ii) how long does the inhibition persist after removing the rHDL from the cells. When the cells were not pre-incubated with the rHDL, there was no inhibition.

Antidepressant-like actions of an AMPA receptor potentiator (LY392098).

LY392098 is a member of a novel class of biarylpropylsulfonamides that potentiates AMPA receptor-mediated responses both in vitro and in vivo. In this study, the effects of LY392098 were evaluated in two "behavioral despair" models (the forced swim and tail suspension tests) commonly used to identify clinically useful antidepressants. LY392098 reduced immobility in the forced swim test in both rats and mice, with a minimum effective dose of 0.

Using a standardized family to teach clinical skills to medical students.

Background: The use of standardized patients has been an accepted instructional methodology in medical education for many years. A logical evolution of this methodology is the creation of a standardized patient family.

Description: This article describes one such standardized family, the Jones family, and how the family is used to teach interpersonal skills, interviewing, communication, counseling, and history-taking skills to medical students.

Pressure sore prevention in nursing homes.

Staff working in nursing homes are caring for ever more dependent residents who are consequently at great risk of developing pressure sores. Mary Clay offers a guide to the essential principles as a teaching aid for all caring staff.

Formation of spherical, reconstituted high density lipoproteins containing both apolipoproteins A-I and A-II is mediated by lecithin:cholesterol acyltransferase.

Previous studies have provided detailed information on the formation of spherical high density lipoproteins (HDL) containing apolipoprotein (apo) A-I but no apoA-II (A-I HDL) by an lecithin:cholesterol acyltransferase (LCAT)-mediated process. In this study we have investigated the formation of spherical HDL containing both apoA-I and apoA-II (A-I/A-II HDL). Incubations were carried out containing discoidal A-I reconstituted HDL (rHDL), discoidal A-II rHDL, and low density lipoproteins in the absence or presence of LCAT.

The effect of dosing regimen on the pharmacokinetics of risedronate.

Aims: To examine the effect of timing of a risedronate dose relative to food intake on the rate and extent of risedronate absorption following single-dose, oral administration to healthy male and female volunteers.

Methods: A single-dose, randomized, parallel study design was conducted with volunteers assigned to four treatment groups (31 or 32 subjects per group, 127 subjects total). Each subject was orally administered 30 mg risedronate.

Effects of granulocyte-colony-stimulating factor on potential normal granulocyte donors.

Background: The use of granulocyte-colony-stimulating factor (G-CSF) to increase the granulocyte count and the yield from leukapheresis in normal donors is leading to renewed interest in granulocyte transfusion. Therefore, it is important to understand the side effects of G-CSF.

Study Design And Methods: We studied the effect of G-CSF on peripheral blood counts and recorded the side effects experienced 24 hours after an injection of G-CSF in normal subjects donating peripheral blood progenitor cells for research.

Rats with hypothalamic obesity are insensitive to central leptin injections.

Genetically determined obesities, involving leptin- and melanocortin-signaling pathways, have focused attention on the four medial hypothalamic nuclei as primary sources of feeding- and metabolically-based obesity. All four medial cell groups contain leptin receptors. To determine which of these cell groups normally mediates the effects of leptin on food intake and body weight gain, we injected colchicine bilaterally into each nucleus and determined the pathophysiological effects of disruption and responsivity to leptin injected intracerebroventricularly.

Remodelling of high density lipoproteins by plasma factors.

Evidence that the high density lipoproteins (HDL) in human plasma are antiatherogenic has stimulated considerable interest in the factors which regulate their structure and function. Plasma HDL consist of a number of subpopulations of particles of varying size, density and composition. This structural heterogeneity is caused by the continual remodelling of individual HDL subpopulations by various plasma factors.

Application of oral bioavailability surrogates in the design of orally active inhibitors of rhinovirus replication.

Previous studies in rats and humans demonstrated poor oral bioavailability of potent in vitro 2-aminobenzimidazole inhibitors of rhinovirus replication due to significant first-pass elimination and possibly also to poor aqueous solubility. Estimations of aqueous solubility, as well as measurements of caco-2 permeability and NADPH dependent compound loss in rat liver microsomal incubations were employed alongside traditional in vivo experiments in rats to guide subsequent chemistry efforts. Retention of activity upon replacement of the metabolically labile vinyl oxime in the lead molecule with a vinyl carboxamide was a major breakthrough; however, oral bioavailability among the latter compounds was variable.

Effect of heat on stored red cells during non-flow conditions in a blood-warming device.

Background And Objectives: While blood is flowing within a transfusion-warming device, the blood temperature is usually less than that applied externally. If the flow is temporarily stopped, the temperature can rise above 37 degrees C in some warming devices. We sought to determine whether temperatures near 45 degrees C achieved during prolonged non-flow conditions in a blood warmer are harmful to red cell integrity.

Collection of two peripheral blood stem cell concentrates from healthy donors.

When peripheral blood stem cell (PBSC) concentrates are used for allogeneic transplants, two or more apheresis procedures must often be performed. To determine how many cells could be collected from healthy people by two back-to-back apheresis procedures and what effect these collections would have on donors, we gave 19 healthy people 5 micrograms kg-1 day-1 and 21 people 10 micrograms kg-1 day-1 of granulocyte colony stimulating factor, filgrastim, for 5 days. We then collected two PBSC concentrates, one on day 5 and one on day 6.

Teaching medical students cancer risk reduction nutrition counseling using a multimedia program.

Background And Objectives: There are many barriers to medical students receiving education about the linkage between nutrition and cancer, including the lack of role models and teachers and insufficient curricular time. We tested the use of a multimedia program as a possible solution to teaching diet-risk assessment and counseling skills.

Methods: Images of Cancer Prevention, The Nutrition Link is a CD-ROM multimedia program that was developed and evaluated by 147 medical students.

Stereoselective metabolism of tazofelone, an anti-inflammatory bowel disease agent, in rats and dogs and in human liver microsomes.

Incubation of (R)-tazofelone and (S)-tazofelone in rat, dog, and human liver microsomes demonstrated that the (R)-tazofelone enantiomer was more rapidly metabolized, with two diastereomeric sulfoxides as the major metabolites formed in all three species. The two diasteresomers epimerized at physiological pH, therefore total sulfoxide formation rates were measured. The formation of the total sulfoxide metabolites followed Michaelis-Menten kinetics.

Formation of apolipoprotein-specific high-density lipoprotein particles from lipid-free apolipoproteins A-I and A-II.

We have shown previously that apolipoprotein A (apoA)-I-containing high-density lipoprotein (HDL) particles are formed by the conjugation of lipid-free apoA-I with lipids derived from other lipoprotein fractions in a process dependent on non-esterified fatty acids, generated by the lipolysis of very-low-density lipoprotein (VLDL) or provided exogenously. In the present study, we show that this process is also able to generate HDL particles containing apoA-II (A-II HDL) and both apoA-I and apoA-II (A-I/A-II HDL). When lipid-free apoA-II was incubated with either VLDLs and lipoprotein lipase or LDLs and sodium oleate, a significant proportion of the apoA-II was recovered in the HDL density fraction.