Very low C-reactive protein in apparently healthy individuals: physiological status or just a reflection of an improved health profile

Abstract

The objective of our study was to determine whether the very low concentrations of C-reactive protein (CRP) detected by high-sensitivity CRP (hs-CRP) assays that one encounters from time to time in apparently healthy individual represent a physiological status or are just a reflection of an improved general health profile. The concentration of hs-CRP was determined by using the Behring BN II nephelometer. The arbitrary cut-off point of hs-CRP (≤0.16mgl^?1) was determined at the lower detection level of the assay. A total of 6588 apparently healthy individuals were screened following exclusion of recent infection/inflammation by using a detailed questionnaire. One hundred and sixty (2.4%) individuals out of the above-mentioned cohort presented hs-CRP concentrations of ≤0.16mgl^?1. They were found to be significantly younger and lean, had an improved lipid profile and an attenuated acute-phase response in terms of lower erythrocyte sedimentation rate and fibrinogen concentration as well as white blood cell count. In addition, these individuals had less atherothrombotic risk factors, except for smoking habits which were as frequent as in those of individuals with a higher hs-CRP concentration. After calculating the concentration of this biomarker following multiple adjustments, the individuals with very low CRP remained with a very low value despite the multiplicity of the adjustments. We raise the possibility that this particular low concentration might represent a physiological status and is not necessarily a result of the improved general health profile per se.     

Effects of Tetraethylammoniumchloride (TEA), Vanadate, and Alkali Ions on the Lateral Leaflet Movement Rhythm of Desmodium motorium (Houtt.) Merr

The period (∼3-5 min) of the ultradian rhythm of the lateral leaflet movement of Desmodium motorium is strongly lengthened (≤30-40%) by the K⁺ channel blocker tetraethylammoniumchloride (20, 30, and 40 mM) and vanadate (0.5 and 1 mM), which is an effective inhibitor of the plasma membrane-bound H⁺ pump. The alkali ions K⁺, Na⁺, Rb⁺, and Cs⁺ (10-40 mM) shorten the period only slightly (≤ 10-15%). Li⁺ (5-30 mM), however, increases the period of the leaflet rhythm drastically (≤80%). We concluded that the plasmalemma-H⁺-ATP-ase-driven K⁺ transport through K⁺ channels is an essential component of the ultradian oscillator of Desmodium, as has been proposed for the circadian oscillator.     

Rheological properties of barley β-glucan

Health benefits of cereal β-glucan are linked to its high viscosity. Although viscosity of β-glucan gum solutions has been reported previously, there are conflicting reports about its behavior at elevated temperatures. Therefore, the viscosity behavior of barley β-glucan gum obtained in a pilot plant (PP) or in a laboratory (LAB) was determined at different shear rates (1.29–129 s⁻¹) and temperatures (0.1–75 °C) in this study. Viscosity decrease with temperature was demonstrated for both gums and activation energy E_a was calculated from the Arrhenius equation. None of the fresh gum solutions exhibited thixotropic behavior at ≤1% (w/w) concentration, but the measurement demonstrated that increased shear rate is not applicable to polymer solutions of low viscosity. Information about rheological properties of β-glucan will lead to better understanding of its behavior under physiological and processing conditions.     

Urinary hydroxylated metabolites of polycyclic aromatic hydrocarbons as biomarkers of exposure in asphalt workers

Background. Fumes and vapours released during laying of hot asphalt mix have been recognised as a major source of exposure for asphalt workers. Objectives. We investigated the relationships between inhalation exposure to asphalt emissions and urinary biomarkers of polycyclic aromatic hydrocarbons (PAHs) in asphalt workers (AW, n=75) and in ground construction workers (CW, n=37). Methods. Total polyaromatic compounds (PAC) and 15 priority PAHs in inhaled air were measured by personal sampling. Hydroxylated PAH metabolites (OH-PAHs) (2-naphthol, 2-hydroxyfluorene, 3-hydroxyphenanthrene, 1-hydroxypyrene, 6-hydroxychrysene and 3-hydroxybenzo[a]pyrene) were determined in urine spot samples collected in three different times during the work week. Results. Median vapour-phase PAC (5.5 µg m^-3), PAHs (≤50 ng m^-3) and OH-PAHs (0.08-1.11 µg l^-1) were significantly higher in AW than in CW, except in the cases of air naphthalene and 2-naphthol. Airborne levels of particle-phase contaminants were similar in the two groups and much lower than vapour-phase levels; metabolites of particulate PAHs were never found in quantifiable amounts. An appreciable increase in OH-PAH levels during the work day and work week was found in AW; median levels for 2-hydroxyfluorene, 3-hydroxyphenanthrene and 1-hydroxypyrene were, respectively, 0.29, 0.08 and 0.18 at baseline; 0.50, 0.18 and 0.29, pre-shift; 1.11, 0.44 and 0.44 µg l^-1, post-shift. Each OH-PAH exhibited a characteristic profile of increase, reflecting differences in half-lives of the parent compounds. In non-smoking subjects, positive correlations were found between vapour-phase PAC or PAHs and OH-PAHs both in pre- and post-shift samples (0.34 ≤ r≤69). Smokers exhibited 2-5-fold higher OH-PAHs than non-smokers, at any time and at both workplaces. Conclusions. Our results suggest that OH-PAHs are useful biomarkers for monitoring exposure to asphalt emissions. The work-related exposure to PAC and PAHs was low in all AW, but urinary metabolites reflected exposure satisfactorily.     

Ring rotation and anomalous metal atom motion in octamethyl ferrocene and spin-lattice relaxation in octamethyl ferrocenium hexafluorophosphate

The dynamics of the metal atom motion in sym octamethyl ferrocene (OMF) has been elucidated over the temperature range 85≤T≤350 K by ⁵⁷Fe Mössbauer effect spectroscopy, and shows a marked increase in the mean-square-amplitude of vibration at 348 K, some 80° below the melting point of the neat solid. Differential scanning calorimetry shows an endothermic peak at about the same temperature, and ΔH is 1.50 kJ mol⁻¹ and ΔS is 4.31 J mol⁻¹ K⁻¹. Corresponding data for OMF⁺PF₆⁻ can be fitted by a relaxation algorithm and confirm the intra-molecular nature of the transition. The spin-lattice relaxation over the above temperature range is fast compared to the characteristic Mössbauer time scale and can be accounted for by a Raman process in the high temperature limit. The transition at 348 K is associated with the onset of ring rotation/libration in the neat solid.     

Improved enzymatic two-phase biotransformation for (R)-phenylacetylcarbinol: Effect of dipropylene glycol and modes of pH control

An octanol/aqueous two-phase process for the enzymatic production of (R)-phenylacetylcarbinol (PAC) has been investigated further with regard to optimal pH control and replacement of 2.5 M MOPS buffer by a low cost solute. The specific rate of PAC production in the 2.5 M MOPS system controlled at pH 7 was 0.60 mg U^-1 h^-1 (reaction completed at 34 h), a 1.6 times improvement over the same 2.5 M MOPS system without pH control (0.39 mg U^-1 h^-1 at 49 h). An improved stability of PDC was evident at the end of biotransformation for the pH-controlled system with 84% residual carboligase activity, while 23% of enzyme activity remained in the absence of pH control. Lowering the MOPS concentration to 20 mM resulted in a lower benzaldehyde concentration in the aqueous phase with a major increase in the formation of by-product acetoin and three times decreased PAC production (0.21 mg U^-1 h^-1). Biotransformation with 20 mM MOPS and 2.5 M DPG as inexpensive replacement of high MOPS concentrations provided similar aqueous phase benzaldehyde concentrations compared to 2.5 M MOPS and resulted in a comparable PAC concentration (92.1 g L^-1 in the total reaction volume in 47 h) with modest formation of acetoin.     

Influence de l'oxygene sur les transferts d'electrons de la photosynthese. II. Influence de tres faibles concentrations en oxygene sur la reduction du NADP par les chloroplastes isoles

Influence of oxygen on the electron transfers of photosynthesis. II. Influence of very low oxygen concentration on the NADP⁺ reduction by isolated chloroplasts

The influence of very low O₂ concentration on the NADP⁺ reduction by isolated spinach chloroplasts has been studied.

The results show that in the presence of very low O₂ concentration (< 0.3%) NADP⁺ reduction is partially inhibited. This inhibition may be partially reversed under some conditions, especially when, in spite of the presence of an O₂ trap (glucose plus glucose oxidase (EC 1.1.3.4)) an O₂ evolution is observed.     

Studies on the interaction between Cd(2+) ions and DNA

Cadmium is a potent carcinogen in rodents and has recently been accepted by the International Agency for Research on Cancer as a category 1 (human) carcinogen, but the molecular mechanism of its action remains largely unclear. It has however been suggested that cadmium-induced carcinogenesis may involve either direct or indirect interaction of Cd²⁺ with DNA. Cd²⁺ is believed to bind covalently with N7 centres of adenine and guanine. At low concentrations (≤50 mM), Cd²⁺ is found to react with plasmid DNA to produce a mixture of Form I and Form II bands whereas at higher concentrations (≥100 mM), Cd²⁺ causes extensive damage to DNA at a pH 5.8 solution of cadmium nitrate. Within the range 0–100 mM (when pH is adjusted to 7.4 by adding NaOH) an increase in concentration of Cd²⁺ is found to cause a decrease in the gel mobility rate of plasmid and an increase in the intensity of the Form II band. When plasmid DNA is digested with BamH1, only the Form III band is observed both in the presence and absence of Cd²⁺. However, the mobility of the band is found to decrease with the increase in the concentration of Cd²⁺. When the enzyme Ssp1 which cuts plasmid DNA at the AT sites is used instead of BamH1, two bands are observed in the presence of cadmium as against one band in the absence of cadmium. These results suggest that Cd²⁺ binds covalently with DNA (possibly at G, A and T centres) and can form intrastrand bifunctional AT adducts but not the GG adducts. It may also be that neither GG nor AT adducts are formed and yet Ssp1 digestion is prevented because of a structural modification introduced in adenine by its interaction with Cd²⁺. In the presence of antioxidants such as cysteine, glutathione and ascorbate (especially cysteine and ascorbate), DNA damage is found to be greater than expected for the combined effects of the antioxidant and Cd²⁺. The increased DNA damage is believed to be due to the formation of reactive oxygen species (ROS).     

Effect of p53 genotype on gene expression profiles in murine liver

The tumor suppressor protein p53 is a key regulatory element in the cell and is regarded as the “guardian of the genome”. Much of the present knowledge of p53 function has come from studies of transgenic mice in which the p53 gene has undergone a targeted deletion. In order to provide additional insight into the impact on the cellular regulatory networks associated with the loss of this gene, microarray technology was utilized to assess gene expression in tissues from both the p53^−/− and p53^+/− mice. Six male mice from each genotype (p53^+/+, p53^+/−, and p53^−/−) were humanely killed and the tissues processed for microarray analysis. The initial studies have been performed in the liver for which the Dunnett test revealed 1406 genes to be differentially expressed between p53^+/+ and p53^+/− or between p53^+/+ and p53^−/− at the level of p ≤ 0.05. Both genes with increased expression and decreased expression were identified in p53^+/− and in p53^−/− mice. Most notable in the gene list derived from the p53^+/− mice was the significant reduction in p53 mRNA. In the p53^−/− mice, not only was there reduced expression of the p53 genes on the array, but genes associated with DNA repair, apoptosis, and cell proliferation were differentially expressed, as expected. However, altered expression was noted for many genes in the Cdc42-GTPase pathways that influence cell proliferation. This may indicate that alternate pathways are brought into play in the unperturbed liver when loss or reduction in p53 levels occurs.     

Effect of nomegestrol acetate on estrone-sulfatase and 17β-hydroxysteroid dehydrogenase activities in human breast cancer cells

It is well recognized that estradiol (E₂) is one of the most important hormones supporting the growth and evolution of breast cancer. Consequently, to block this hormone before it enters the cancer cell or in the cell itself, has been one of the main targets in recent years. In the present study we explored the effect of the progestin, nomegestrol acetate, on the estrone sulfatase and 17β-hydroxy-steroid dehydrogenase (17β-HSD) activities of MCF-7 and T-47D human breast cancer cells. Using physiological doses of estrone sulfate (E₁S: 5 × 10⁻⁹ M), nomegestrol acetate blocked very significantly the conversion of E₁S to E₂. In the MCF-7 cells, using concentrations of 5 × 10⁻⁶ M and 5 × 10⁻⁵ M of nomegestrol acetate, the decrease of E₁S to E₂ was, respectively, −43% and −77%. The values were, respectively, −60% and −71% for the T-47D cells. Using E₁S at 2 × 10⁻⁶ M and nomegestrol acetate at 10⁻⁵ M, a direct inhibitory effect on the enzyme of −36% and −18% was obtained with the cell homogenate of the MCF-7 and T-47D cells, respectively. In another series of studies, it was observed that after 24 h incubation of a physiological concentration of estrone (E₁: 5 × 10⁻⁹ M) this estrogen is converted in a great proportion to E₂. Nomegestrol acetate inhibits this transformation by −35% and −85% at 5 × 10⁻⁷ M and 5 × 10⁻⁵ M, respectively in T-47D cells; whereas in the MCF-7 cells the inhibitory effect is only significant, −48%, at 5 × 10⁻⁵ M concentration of nomegestrol acetate. It is concluded that nomegestrol acetate in the hormone-dependent MCF-7 and T-47D breast cancer cells significantly inhibits the estrone sulfatase and 17β-HSD activities which converts E₁S to the biologically active estrogen estradiol. This inhibition provoked by this progestin on the enzymes involved in the biosynthesis of E₂ can open new clinical possibilities in breast cancer therapy.     

Influence of 2,4-D, IAA, and duration of callus induction in anther cultures of spring wheat

Culture media and environmental factors may significantly influence the yield of haploid plants from anther cultures. Our objectives were to identify a combination of 2,4-dichlorophenoxyacetic acid (2,4-D) and indoleacetic acid (IAA) concentrations which produce the maximum number of haploid plants, and to evaluate the effects of duration in induction medium on calli induction, plant regeneration, and green plant production from anther cultures in spring wheat. Significant (P ≤ 0.01) plant growth regulator concentration effects (2,4-D and IAA) were observed on the number of calli, green plants and albino plants produced, and on direct plant regeneration. Addition of 2,4-D to the induction medium resulted in significantly (P ≤ 0.01) higher means for all anther culture components compared to IAA> While addition of 2,4-D significantly (P ≤ 0.01) reduced plant regeneration, it substantially increased green plant percentage at a 0.3-mg l⁻¹ concentration of IAA. Use of response functions to estimate the maximum effective 2,4-D × IAA combination implied that higher 2,4-D levels in the induction medium should be investigated, and that the optimum hormone combination differs for plant regeneration and green plant percentage. Significant (P ≤ 0.01) effects of duration on callus induction medium were observed for plant regeneration and green plant percentage.     

Simultaneous production of two different gel-forming exopolysaccharides by an Alteromonas strain originating from deep sea hydrothermal vents

Exopolysaccharide production by the marine bacterium Alteromonas sp. strain 1644 was shown to be stimulated by restricted growth conditions and was optimized in nitrogen limited fed-batch cultures. Exopolysaccharides were either partly secreted in the medium or stayed firmly cell-associated. The cell-polysaccharide associations could be destroyed by dialysis against distilled water, allowing polysaccharide purification. The chemical and rheological characterization of this last polysaccharide showed that it was different from the secreted polysaccharide that has been previously described (polysaccharide 1644). At low ionic concentration (below 0.03 M whatever the nature of the ions), solutions of this new polysaccharide had very low viscosities. However, at higher ionic concentration, it formed a gel or exhibited in solution at low polymer concentration an unusually high temperature dependent viscosity. This behaviour was also dependent on the nature of the ions and the following sequences for cations and anions were NH4 ⁺ > Mg²⁺ > Na ⁺ > Li⁺ > K⁺ > TMA⁺ and Br⁻ > NO₃⁻ > SO₄²⁻ > Cl⁻ > I⁻ respectively.     

The sodium cycle. II. Na-coupled oxidative phosphorylation in Vibrio alginolyticus cells

The role of Na⁺ in Vibrio alginolyticus oxidative phosphorylation has been studied. It has been found that the addition of a respiratory substrate, lactate, to bacterial cells exhausted in endogenous pools of substrates and ATP has a strong stimulating effect on oxygen consumption and ATP synthesis. Phosphorylation is found to be sensitive to anaerobiosis as well as to HQNO, an agent inhibiting the Na⁺-motive respiratory chain of V. alginolyticus. Na⁺ loaded cells incubated in a K⁺ or Li⁺ medium fail to synthesize ATP in response to lactate addition. The addition of Na⁺ at a concentration comparable to that inside the cell is shown to abolish the inhibiting effect of the high intracellular Na⁺ level. Neither lactate oxidation nor Δω generation coupled with this oxidation is increased by external Na⁺ in the Na⁺-loaded cells. It is concluded that oxidative ATP synthesis in V. alginolyticus cells is inhibited by the artificially imposed reverse ΔPNa, i.e., [Na⁺]_in > [Na⁺]_out. Oxidative phosphorylation is resistant to a protonophorous uncoupler (0.1 mM CCCP) in the K⁺-loaded cells incubated in a high Na⁺ medium, i.e., when ΔpNa of the proper direction ([Na⁺]_in < [Na⁺]_out) is present. The addition of monensin in the presence of CCCP completely arrests the ATP synthesis. Monensin without CCCP is ineffective. Oxidative phosphorylation in the same cells incubated in a high K⁺ medium (ΔpNa is low) is decreased by CCCP even without monensin. Artificial formation of ΔpNa by adding 0.25 M NaCl to the K⁺-loaded cells (Na⁺ pulse) results in a temporary increase in the ATP level which spontaneously decreases again within a few minutes. Na⁺ pulse-induced ATP synthesis is completely abolished by monensin and is resistant to CCCP, valinomycin and HQNO. 0.05 M NaCl increases the ATP level only slightly. Thus, V. alginolyticus cells at alkaline pH represent the first example of an oxidative phosphorylation system which uses Na⁺ instead of H⁺ as the coupling ion.     

Detection of heavy metal toxicity using cardiac cell-based biosensor

Biosensors incorporating mammalian cells have a distinct advantage of responding in a manner which offers insight into the physiological effect of an analyte. To investigate the potential applications of cell-based biosensors on heavy metal toxicity detection, a novel biosensor for monitoring electrophysiological activity was developed by light-addressable potentiometric sensor (LAPS). Extracellular field potentials of spontaneously beating cardiomyocytes could be recorded by LAPS in the range of 20 μV to nearly 40 μV with frequency of 0.5–3 Hz. After exposed to different heavy metal ions (Hg²⁺, Pb²⁺, Cd²⁺, Fe³⁺, Cu²⁺, Zn²⁺; in concentration of 10 μM), cardiomyocytes demonstrated characteristic changes in terms of beating frequency, amplitude and duration under the different toxic effects of ions in less than 15 min. This study suggests that, with the physiological monitoring, it is possible to use the cardiac cell-based biosensor to study acute and eventually chronic toxicities induced by heavy metal ions in a long-term and no-invasive way.     

Reduction of daunorubicin in the presence of sulfur-containing peptides

Daunorubicin, an anthracycline antitumor antibiotic, was reduced in the presence of reduced (GSH) or oxidized (GSSG) glutathione to evaluate the possibilities of detoxification or of potentiation of the drug by these compounds. The reductants were ^.COO⁻ free radicals produced by γ radiolysis. In both cases, the final product is 7-deoxydaunomycinone, i.e., the same as without glutathione. The reduction yield is also the same as without GSH or GSSG (0.23 μmol·J⁻¹). No glutathione depletion was observed. Limits for the rate constants of some possible nonenzymatic detoxification reactions are given. To evaluate the possible interactions of daunorubicin with sulfur-containing proteins, the reduction of this drug by ^.COO⁻ free radicals was also studied in the presence of a polypeptide containing two disulfide bridge are, respectively, 0.23 μmol·J⁻¹ 7-deoxydaunomycinone. The yields of reduction of the drug and of a protein disulfide bridge are, respectively, 0.23 μmol·J⁻¹ and ≤ 6 nmol·J⁻¹. These values indicate thet disulfide radical anions of the protein can reduce the drug, giving back the disulfide bridge, but that the drug transients niether oxidize nor reduce the protein.     

Characterization of functional VIP/PACAP receptors in the human erythroleukemic HEL cell line

R. LEMA-KISOKA, N. HAYEZ, I. LANGER, P. ROBBERECHT, E. SARIBAN AND C. DELPORTE. Characterization of functional VIP/PACAP receptors in the human erythroleukemic HEL cell line. PEPTIDES. The presence of VIP/PACAP receptors was investigated on the human erythroleukemic cell line HEL. Specific binding of [¹²⁵I]-PACAP or [¹²⁵I]-VIP on HEL cells or membranes was very low and did not allow to perform competition curves. At 37°C PACAP transiently increased cAMP levels in the presence of the non-specific phosphodiesterase inhibitor IBMX, suggesting rapid desensitization. Kinetic studies revealed that optimal conditions to measure the EC₅₀ of PACAP(1–27) were 10 min at 20°C. Under those conditions, PACAP-related peptides increased cAMP levels with EC₅₀ in agreement with the pharmacological profile of the VPAC₁ receptor subtype: PACAP = VIP > [K¹⁵, R^16, L²⁷]VIP(1–7)/GRF(8–27) = [R¹⁶]ChSn (two VPAC₁ agonists) HELODERMIN = secretin. RO 25–1553, a selective activator of VPAC₂ receptor was inactive at 1 μM. Dose-response curves of VPAC₁ agonist molecules (PACAP, VIP, [K¹⁵, R¹⁶, L²⁷]VIP(1–7)/GRF(8–27), [R¹⁶]ChSn) were shifted to the right by the VPAC₁ receptor antagonist [AcHis¹, D-Phe², Lys¹⁵, Leu¹⁷]VIP(3–7)/GRF(8–27), with a K_i of 3 ± 1 nM (n = 3). The presence of VPAC₁ receptor mRNA was confirmed by RT-PCR. Preincubation with PACAP or PMA showed that VPAC₁ receptors underwent homologous and heterologous desensitization.

This study provides the first evidence for the expression of functional VPAC₁ receptors undergoing rapid desensitization in HEL cells.     

Kinetics of Reduction of Hypervalent Iron in Myoglobin by Crocin in Aqueous Solution

Crocin in aqueous solution is oxidized by ferrylmyoglobin, MbFe(IV)=O, in a second order reaction with k = 183 1 · mol^-1 · s^-1, AH^‡₂₉₈ = 55.0 kJ · mol^-1, and ΔLS^‡₂₉₈ = -17 J · mol^-1 K^-1 (pH = 6.8, ionic strength 0.16 (NaCl), 25°C), as studied by stopped-flow spectroscopy. The reaction has 1:1 stoichiometry to yield metmyoglobin, MbFe(III), and has AG^o = -11 kJ · mol^-1, as calculated from the literature value E⁰ = +0.85 V (pH = 7.4) vs. NHE for MbFe(IV)=O/MbFe(III) and from the half-peak potential +0.74 V (vs. NHE in aqueous 0.16 NaCl, pH = 7.4) determined by cyclic voltammetry for the one-electron oxidation product of crocin, for which a cation radical structure is proposed and which has a half-peak potential of +0.89 V for its formation from the two-electron oxidation product of crocin. The fer-rylmyoglobin protein-radical, MbFe(IV)=O, reacts with crocin with 2:l stoichiometq to yield MbFe(IV)= 0, as determined by ESR spectroscopy, in a reaction faster than the second order protein-radical generating reaction between H₂O₂ and MbFe(III), for which latter reaction k = 137 L · mol^-1 · s^-1, ΔH^‡₂₉₈ = 51.5 kJ · mol^-1, and ΔH^‡₂₉₈ = -31 J · mol^-1 · K^-1 (pH = 6.8, ionic strength = 0.16 (NaCI), 25°C) was determined. Based on the difference between the stoichiometry for the reaction between crocin and each of the two hypervalent forms of myoglobin, it is concluded in agreement with the determined half peak reduction potentials, that the crocin cation radical is less reducing compared to crocin, as the cation radical can reduce the protein radical but not the iron(IV) centre in hypervalent myoglobin.     

Nasal Cavity Lining Fluid Ascorbic Acid Concentration Increases in Healthy Human Volunteers Following Short Term Exposure to Diesel Exhaust

To determine if diesel exhaust (DE) exposure modifies the antioxidant defense network within the respiratory tract lining fluids, a randomized, single blinded, crossover control study using nasal lavage and flexible video bronchoscopy with bronchial and broncho-alveolar lavage was performed. Fifteen healthy, nonsmoking, asymptomatic subjects were exposed to filtered air or diluted diesel exhaust (300mg m^-3 partic-ulates, l.6ppm nitrogen dioxide) for one hour on 2 separate occasions, at least three weeks apart. To examine the kinetics of any DE-induced antioxidant reactions, nasal lavage fluid and blood samples were collected prior to, immediately after, and 5¹/₂ hours post exposure. Bronchoscopy was performed 6 hours after the end of DE exposure. Ascorbic acid, uric acid and reduced glutathone (GSH) concentrations were determined in nasal, bronchial, bronchoalveolar lavage and plasma samples. Malondialdehyde (MDA) and protein carbonyl concentrations were determined in plasma and bronchoalveolar lavage samples. Nasal lavage ascorbic acid concentration increased 10-fold during DE exposure [1.02 (0.26-2.09) Vs 7.13 (4.66-10.79) μmol/L^-1, but returned to basal levels 5.5 hours post-exposure [0.75 (0.26-1.51) μmol/L^-']. There was no significant effect of DE exposure on nasal lavage uric acid or GSH concentration. DE exposure did not influence plasma, bronchial wash, or bronchoalveolar lavage antioxidant concentrations and no change in MDA or protein carbonyl concentrations were found. The physiological response to acute DE exposure is an increase in the level of ascorbic acid in the nasal cavity. This response appears to be sufficient to prevent further oxidant stress in the respiratory tract of normal individuals.     

Biotransformation of ferulic acid to acetovanillone using Rhizopus oryzae

Microbial transformation of ferulic acid to acetovanillone was studied using growing cells of Rhizopus oryzae. Ferulic acid was added to the growing medium (0.5 g L^-1) and incubated for 12 days. The progress of formation of metabolites was monitored by GC and GC-MS after extraction with ethyl acetate. The major metabolite was acetovanillone with minor metabolites formed, such as dihydroferulic acid, coniferyl alcohol and dihydroconiferyl alcohol. Traces of metabolites (≤1-3%), such as vanillin, vanillyl alcohol, vanillic acid and phenyl ethyl alcohol, were also produced. Formation of 4-vinyl guaiacol increased from day 1 (12.4%), reaching a maximum on day 4 (31.7%), and reducing to a minimum on day 12 (3.1%). The formation of acetovanillone increased only from day 2 onward, and reached a maximum (49.2%) on day 12. The optimum concentration of ferulic acid to be added into the medium was found to be only 0.5 g L^-1, as any increase in concentration (0.75 and 1.0 g L^-1) precipitated the precursor, resulting in no further degradation.     

Growth response of major USA cowpea cultivars: II. Effect of salinity on leaf gas exchange

In an effort to elucidate the physiological processes involved in cowpea differential growth response of four major USA cowpea cultivars (CB5, CB27, 8517 and 7964) to increasing salinity, we investigated the effect of salinity on leaf gas exchange of net photosynthetic rate per unit leaf mass (Pnm) and per unit leaf area (Pna), and stomatal conductance (gs) of the four cowpea cultivars. The experiment was set up as a standard split-plot design in which cowpea plants were grown in greenhouse sand tanks irrigated with nutrient solutions. Seven salinities ranging from 2.6 to 20.5 dS m⁻¹ were constructed based on Colorado River water salt composition with NaCl, CaCl₂ and MgSO₄ as the salinization salts. Light-saturated Pnm, Pna and gs of fully expanded trifoliage were examined at the vegetative growth and flowering stages, and the data were analyzed using a split-plot analysis of variance (ANOVA) model. We found a highly significant (P ≤ 0.0001) reduction of Pnm, Pna and gs due to salinity. The responses of Pnm, Pna and gs to salinity could be further described by a general model of log(y) = a₁ + a₂x + a₃x², where y represents either Pnm, Pna, or gs; a₁, a₂ and a₃, empirical constants; x, salinity. We found that Pnm was more sensitive to salinity than Pna. Additionally, we found that increasing stomatal closure with increasing salinity might limit Pnm or Pna. While we did not find any significant difference (P > 0.05) of Pnm and Pna among the four cultivars, we did find a significant difference (P ≤ 0.05) in gs. No significant salt × cultivar interaction effect (P > 0.05) was found with Pnm, Pna and gs indicating that the four cowpea cultivars have the same response pattern of their leaf gas exchange to salinity.