The adherence-associated Fdp fasciclin I domain protein of the biohydrogen producer Rhodobacter sphaeroides is regulated by the global Prr pathway.

Expression of fdp, encoding a fasciclin I domain protein important for adherence in the hydrogen-producing bacterium Rhodobacter sphaeroides, was investigated under a range of conditions to gain insights into optimization of adherence for immobilization strategies suitable for H2 production. The fdp promoter was linked to a lacZ reporter and expressed in wild type and in PRRB and PRRA mutant strains of the Prr regulatory pathway. Expression was significantly negatively regulated by Prr under all conditions of aerobiosis tested including anaerobic conditions (required for H2 production), and aerobically regardless of growth phase, growth medium complexity or composition, carbon source, heat and cold shock and dark/light conditions. Negative fdp regulation by Prr was reflected in cellular levels of translated Fdp protein. Since Prr is required directly for nitrogenase expression, we propose optimization of Fdp-based adherence in R. sphaeroides for immobilized biohydrogen production by inactivation of the PrrA binding site(s) upstream of fdp.

Size-exclusion chromatography of poly(ethylene 2,6-naphthalate).

A solvent mixture of 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) and dichloroacetic acid (DCAA) is used to dissolve difficultly soluble poly(ethylene 2,6-naphthalate) (PEN). Solutions can be diluted and analyzed in a common size-exclusion chromatography (SEC) eluent, HFIP. The HFIP/DCAA mixture is better at dissolving PEN than either solvent individually and it is easier and safer to work with than phenolic and strongly acidic eluents. Dissolution temperatures between 50 and 60 °C are sufficiently low to minimize hydrolytic degradation of the polyester. PEN does not dissolve in the solvent mixture if the water concentration is greater than 0.76 wt%, and preferably the water content should be less than 0.13 wt% to eliminate minor prepeak artifacts. The procedure is suitable for PEN that is less than 48% crystalline, including prepolymers, oriented films and some solid-state polymerized materials. Highly crystalline polymers can be melt-quenched into a more amorphous state to render them soluble. The dilute solution conformational properties of PEN are compared to PET in HFIP, and molar mass-intrinsic viscosity scaling constants and unperturbed dimensions are calculated from SEC data.

Computing with almost periodic functions.

This paper develops a method for discrete computational Fourier analysis of functions defined on quasicrystals and other almost periodic sets. A key point is to build the analysis around the emerging theory of quasicrystals and diffraction in the setting on local hulls and dynamical systems. Numerically computed approximations arising in this way are built out of the Fourier module of the quasicrystal in question and approximate their target functions uniformly on the entire infinite space. The methods are entirely group theoretical, being based on finite groups and their duals, and they are practical and computable. Examples of functions based on the standard Fibonacci quasicrystal serve to illustrate the method (which is applicable to all quasicrystals modeled on the cut-and-project formalism).

Determination of sodium artesunate in plasma using ion-pairing high-performance liquid chromatography.

A chromatographic method is described for the determination of sodium artesunate in plasma. This includes cetyltrimethylammonium bromide as a cationic pairing ion in a reversed-phase system using an octadecylsilica 100 x 4.6 mm I.D. 3 microm analytical column with a mobile phase of acetonitrile/acetate buffer at pH7. Column switching incorporating a 5 microm octadecylsilica 100 x 4.6 mm I.D. precolumn is used in addition to off-line solid-phase extraction for pretreatment of plasma samples in order to eliminate interference from endogenous components. Detection is by post-column derivatisation with 1.0 M methanolic KOH followed by UV detection at 289 nm. Calibration is linear over the range 100-1600 ng ml(-1) and the limit of detection is estimated as 20 ng ml(-1). Illustrative results are shown of the artesunate plasma levels determined by the proposed method following the administration of artesunate as tablets and as suppositories to healthy volunteers.

Automated In Vitro Dermal Absorption (AIVDA): predicting skin permeation of atrazine with finite and infinite (swimming/bathing) exposure models.

The Automated In Vitro Dermal Absorption (AIVDA) HPLC method developed in our laboratory for finite dose tests was developed further for infinite dose swimming/bathing exposure tests and for monitoring skin viability during the permeation assay. Skin absorption of the herbicide atrazine was tested under both finite and infinite dose conditions and the data compared to that obtained using the Bronaugh flow-through cell. Confirmation that skin viability was maintained throughout the AIVDA 24-hr infinite dose tests without phenol was obtained using a novel Radio-HPLC method that was developed to monitor glycolytic 14C-lactic acid formation in 14C-glucose spiked receiver solution. Advantages of the AIVDA method (e.g. rapid, sensitive, versatile, cost-effective analysis) together with its disadvantages (e.g. need for manual dexterity, lack of receiver albumin, compound retention time, limit of sampling interval) are discussed.

Isolation of developmental mutants of the ascidian Ciona savignyi.

Ascidians have been used extensively as model animals for experimental embryology. We report here the results of a pilot study with the aim of developing genetic methods for the ascidian Ciona savignyi. The chemical mutagen N-ethyl-N-nitrosourea (ENU) was used to induce point mutations. F1 animals, produced by using sperm from ENU-treated animals to fertilize untreated eggs, were grown to reproductive age. Sperm and eggs collected from the hermaphrodite F1 adults were used to generate self-fertilized F2 broods, which were then screened for recessive, zygotically acting mutations. Animals carrying potential mutations were outcrossed to wild type to test for the heritability of the phenotypes. We report on a number of mutants isolated using this method, including several with abnormalities in tail and notochord development.

Mutations affecting tail and notochord development in the ascidian Ciona savignyi.

Ascidians are among the most distant chordate relatives of the vertebrates. However, ascidians share many features with vertebrates including a notochord and hollow dorsal nerve cord. A screen for N-ethyl-N-nitrosourea (ENU)-induced mutations affecting early development in the ascidian Ciona savignyi resulted in the isolation of a number of mutants including the complementing notochord mutants chongmague and chobi. In chongmague embryos the notochord fails to develop, and the notochord cells instead adopt a mesenchyme-like fate. The failure of notochord development in chongmague embryos results in a severe truncation of tail, although development of the tail muscles and caudal nerve tracts appears largely normal. Chobi embryos also have a truncation of the tail stemming from a disruption of the notochord. However, in chobi embryos the early development of the notochord appears normal and defects occur later as the notochord attempts to extend and direct elongation of the tail. We find in chobi tailbud embryos that the notochord is often bent, with cells clumped together, rather than extended as a column. These results provide new information on the function and development of the ascidian notochord. In addition, the results demonstrate how the unique features of ascidians can be used in genetic analysis of morphogenesis.

Cross-sectional area of the right and left internal jugular veins.

OBJECTIVE: To compare the cross-sectional area (CSA) of the right internal jugular vein (RIJV) with the left internal jugular vein (LIJV) using two-dimensional ultrasound and to measure the response to the Valsalva maneuver in both the supine and Trendelenburg positions. DESIGN: Prospective and randomized. SETTING: University-affiliated hospital. PARTICIPANTS: Fifty healthy adult volunteers. INTERVENTIONS: The CSA of both the RIJV and LIJV was measured with a 5-MHz, two-dimensional surface transducer before and during a 10-second Valsalva maneuver with the subjects in the supine position, and then with the subjects in a 10 degree Trendelenburg tilt. MEASUREMENTS AND MAIN RESULTS: After the baseline measurements were performed, the subjects were divided into two groups based on the CSA of the RIJV and LIJV. Group 1 had an LIJV CSA equal to or greater than that of the RIJV (n = 10) and group 2 had an LIJV CSA less than that of the RIJV (n = 40). Of the latter 40 patients, 17 (34%) had an LIJV CSA less than 50% of that of the RIJV. In both groups, the CSA of both veins increased significantly with the Valsalva maneuver, Trendelenburg tilt, and both maneuvers combined. CONCLUSION: The findings suggest that in one third of adults (34%), the LIJV is significantly smaller compared with the RIJV and, combined with operator inexperience, may influence the success rate and risk for complications. Thus, the use of ultrasound and maneuvers that increase CSA is suggested during LIJV cannulation.

Comparisons of the separations of some neutral analytes by LC, MEKC, and CEC.

The relative utility of high-performance liquid chromatography, micellar electrokinetic chromatography (MEKC), and capillary electrochromatography (CEC) is examined for the separation of essentially uncharged solute mixtures. Three model systems are used for which separations by reversed-phase liquid chromatography had been established. These consisted of a set of three substituted hydroxybenzoates; a mixture of six structurally closely related steroids; and the multicomponent aminoglycoside antibiotic, teicoplanin. These sets represented a range of difficulty in achieving separations by reversed-phase LC. It was found that equivalent or better separations for all systems could be established by MEKC and CEC. Both electrophoretic techniques offer much higher peak efficiencies than LC, and MEKC is found to be superior to CEC in terms of peak efficiencies and ruggedness of operation.

In vitro dermal absorption of two commercial formulations of 2,4-dichlorophenoxyacetic acid dimethylamine (2,4-D amine) in rat, guinea pig and human skin.

In vitro dermal absorption studies with rat, hairless guinea pig and human skin were conducted employing Bronaugh flow-through cells for two commercial formulations of the herbicide, 2,4-dichlorophenoxyacetic acid dimethyl amine (2,4-D amine) and in vivo studies were conducted with rats. The Clean Crop (CC) and Wilbur-Ellis (WE) 2,4-D amine formulations gave similar absorption values, ranging from 21 to 30% in vitro in all three species, except for absorption from WE in guinea pig skin [16 +/- 4.7% (n = 4)], which was significantly less (Student's t-test; P < 0.05) than absorption from WE formulation for human skin [28 +/- 2.6% (n = 4)]. A profound 'washing-in' effect of the soap wash conducted at 24 hr post-treatment was observed for all three species in vitro, and this effect was much more pronounced than in previous studies with 2,4-D where more dilute topical doses were employed. Dermal absorption of both 2,4-D amine formulations was significantly less for rats tested in vivo (16-17%) than for the skin from the same rats tested in vitro (26-30%). The lower percentage absorption observed in vivo was thought to be due to 'rub-off' of the dose application, as 68-78% of the dose was detected in the foam rubber patches used to protect the dose site. The inability to demonstrate greater permeability of animal skin to skin from the one human subject tested, the observation of a soap 'washing-in' effect, and the apparent overprediction of field exposure by both the in vivo and in vitro data were all factors considered to have important implications for accurate assessment of occupational exposure to 2,4-D.

Relationship between feeding pattern and body mass index in 220 free-living people in four age groups.

OBJECTIVE: To assess the relationship between feeding pattern and body mass index in free-living humans. DESIGN AND SUBJECTS: Feeding pattern was assessed from 220 7-day weighed dietary records. 187 records were obtained from three separate existing studies, and reanalysed. These studies contained data on three age groups in the British population; Elderly group (n = 88), Middle-aged group (n = 40), Working age group (n = 59). A separate study of 13-14 year olds living in Croydon was conducted from which 33 usable diet records were collected to produce a fourth, Adolescent group. RESULTS: 'Nibbling' and greater energy intakes at breakfast were associated with a lower body mass index (BMI) in the Adolescent group. In the Middle-aged group, greater energy intakes at breakfast and lower energy intakes during the evening were associated with a lower BMI. However, when diet records which produced unreasonably low energy intakes were removed from the analysis, these relationships disappeared except for energy intakes at breakfast and BMI in the Adolescent group. CONCLUSION: It is suggested that the relationship between feeding pattern and BMI observed in the Adolescent and Middle-aged groups was caused by underestimation of 'habitual' energy intake from snacks and the omission of breakfast by females and those who were overweight. The lack of relationship in the Working age group was attributed to the fact that more individuals in this group appeared to report valid diet records. Reported energy intake was directly related to BMI in the Working age group, but was not related to BMI in the other three age groups. It is concluded that feeding pattern is not a major factor in determining BMI in humans. Also, since snacks have a relatively high sugar and low fat composition compared with meals, it is suggested that biased under-reporting of snacks by the obese could produce spurious results from free-living studies which show that obesity is related to the proportion of energy from fat in the diet.

Dermal exposure to environmental contaminants in the Great Lakes.

This paper reviews the literature to determine the importance of the dermal route of exposure for swimmers and bathers using Great Lakes waters and summarizes the chemical water contaminants of concern in the Great Lakes along with relevant dermal absorption data. We detail in vivo and in vitro methods of quantifying the degree of dermal absorption and discuss a preference for infinite dose data as opposed to finite dose data. The basic mechanisms of the dermal absorption process, routes of chemical entry, and the environmental and physiological factors affecting this process are also reviewed, and we discuss the concepts of surface slick exposure to lipophilic compounds and the adsorption of contaminants to water sediment. After presenting mathematical constructs for calculating the degree of exposure, we present in vitro data concerning skin absorption of polyaromatic hydrocarbons adsorbed to Great Lakes water sediment to show that in a worst-case scenario exposure via the dermal route can be equally important to the oral route. We have concluded that prolonged exposure of the skin, especially under conditions that may enhance dermal absorption (e.g., sunburn) may result in toxicologically significant amounts of certain water contaminants being absorbed. It is recommended that swimming should be confined to public beaches, people should refrain from swimming if they are sunburned, and skin should be washed with soap as soon as possible following exposure. Future studies should be conducted to investigate the importance of the dermal exposure route to swimmers and bathers.

Determination of proguanil and metabolites in small sample volumes of whole blood stored on filter paper by high-performance liquid chromatography.

A method is reported for the determination of proguanil and its two metabolites cycloguanil and 4-chlorophenylbiguanide in whole blood and plasma samples obtained by thumbprick and stored dry on filter paper. The sample preparation involves liquid extraction from the filter paper and subsequent solid-phase extraction using C8 Bond-Elut cartridges. Separation and quantification is by a previously reported ion-pairing high-performance liquid chromatographic system with ODS Hypersil as stationary phase and an 50:50 acetonitrile-pH 2 phosphate buffer mobile phase containing 200 mM sodium dodecylsulphate as ion-pairing agent. The analytical characteristics of the method are reported. Representative concentrations are shown as a function of time from a human subject after ingestion of a single 200-mg dose of proguanil hydrochloride. Typical ranges of concentration detected by the proposed method in human subjects were proguanil 12-900 ng/ml, cycloguanil 16-44 ng/ml and 4-chlorophenylbiguanide 1.5-10 ng/ml in whole blood.

In vivo and in vitro dermal absorption of benzo[a]pyrene in rat, guinea pig, human and tissue-cultured skin.

Cross-species in vitro dermal absorption tests were conducted with 14C-labelled benzo[a]pyrene dissolved in acetone and applied to dermatomed skin (0.5 mm thickness) at comparable dose rates (8-13 micrograms/cm2). Skin absorption was determined using the Bronaugh in vitro flow-through procedure. The percentage (%) dermal absorption included the % 14C-activity detected persisting in the skin added to that detected in the receiver solution. Listed in decreasing order, total % in vitro dermal absorption obtained by 48 h postexposure was: 95 +/- 9.6% (rat), 51 +/- 3.0% (hairless guinea pig), 43 +/- 8.7% (human; 50-year-old), 34 +/- 12.4% (Testskin) and 23 +/- 5.3% (human; 32-year-old). Comparative in vivo studies demonstrated urinary recovery of 8 +/- 1.8% and 25 +/- 5.0% for rats (dose rate: 6 micrograms/cm2) and hairless guinea pigs (dose rate: 9 micrograms/cm2), respectively. Total faecal recovery was 61 +/- 6.0% and 43 +/- 6.1% for rats and guinea pigs, respectively. Necropsies conducted at 14 days postexposure demonstrated total 14C-activity tissue recoveries of 0.5 +/- 0.13% and 0.6 +/- 0.17% in rats and guinea pigs, respectively. Including the 14C-activity extracted from the skin removed from the dose site at 14 days postexposure, the total % in vivo dermal absorbtion was 70 +/- 7.6% and 68 +/- 9.3% for rats and guinea pigs, respectively. In summary, the in vitro data was consistent with the in vivo data in demonstrating that 14C-benzo[a]pyrene was well absorbed through skin.

Sources of energy from meals versus snacks in 220 people in four age groups.

OBJECTIVES: To assess meals versus snacks in terms of their contribution to total daily energy intake (TDI), macronutrient composition, and food commodity profile. DESIGN AND SUBJECTS: Meals and snacks were assessed from 220 7-day weighed dietary records. 187 records were obtained from three separate existing studies, and reanalysed. These studies contained data on three different age groups in the British population; elderly group (n = 88), middle-aged group (n = 40), young adult group (n = 59). A separate study of 13-14-year-olds living in Croydon was conducted from which 33 usable diet records were collected (adolescent group). RESULTS: Boys in the adolescent group consumed more of their TDI as snacks (29.0%) compared with men in the young adult (18.9%) and elderly groups (16.6%), but not the middle-aged group (25.8%). Females consumed about the same percentage of their TDI as snacks; adolescent group 23.6%, young adult group 19.4%, middle-aged group 21.4%, elderly group 17.9%. Meals were higher in protein and fat, and lower in total sugars, compared with snacks. Chocolate confectionery, crisps and fizzy drinks and squashes were popular snack foods in the adolescent group. Unlike snacks, the food commodity profiles of meals were similar in all age groups. CONCLUSIONS: This study shows that foods and drinks consumed as snacks by the British public, including the elderly, have a relatively high total sugar composition. These results add to the concern relating snack foods with dental caries.

Light and electron microscopic immunocytochemistry of FMRFamide and neuropeptide F immunoreactivities in the human blood fluke, Schistosoma mansoni.

The localisation and distribution of FMRF amide and neuropeptide F (NPF) immunoreactivities in the nervous system of adult male and female Schistosome mansoni have been determined by an indirect immunofluorescent technique in conjunction with confocal scanning laser microscopy (CSLM). The patterns of immunostaining were similar for the two peptides. In the central nervous system (CNS) immunoreactivity was evident in nerve cells and fibres in the anterior ganglia, central commissure and three pairs of nerve cords. In the peripheral nervous system (PNS), immunoreactivity was present in nerve plexuses associated with the pharynx, oral and ventral suckers, the subtegumental musculature and with both the gynaecophoric canal and in nerve fibres innervating the dorsal tubercles of the male. In the reproductive system of the male and female worms, immunostaining was only observed around the ootype/Mehlis' gland complex in the female. A post-embedding, IgG-conjugated colloidal gold immunostaining technique was employed to examine the subcellular distribution of FMRF amide immunoreactivity in the CNS of S. mansoni. Gold labelling of peptide was localised over dense-cored vesicles within nerve processes constituting the neuropile of the anterior ganglia. Blocking studies with homologous and heterologous peptides indicate that the immunostaining patterns are due to two distinct peptide molecules.

Contact dermatitis from the old formula E45 cream.

In the past 4 years, a high incidence (118/362) of positive patch test reactions to E45 cream were noted in 2 patch testing clinics. 18/54 of those patch tested to all the ingredients demonstrated allergies to ingredients. The most frequent was triethanolamine; lanolin allergy occurring in only 1 patient. The remaining reactions may be explained as irritant reactions resulting from triethanolamine stearate (TES) formation within the cream. The irritancy of triethanolamine stearate was demonstrated in patients and controls. Conductivity studies showed that TES arises from the combination of the ingredients triethanolamine and stearic acid. The formulation of E45 cream was being changed at the time of writing, with the removal of triethanolamine from the product.