High-performance liquid chromatographic assay for the determination of sulfadoxine and N-acetyl sulfadoxine in plasma from patients infected with sensitive and resistant Plasmodium falciparum malaria

A reversed-phase high-performance liquid chromatographic method using a mobile phase of acetonitrile-methanol-trifluoroacetic acid-water (16.1:7.2:0.1:76.6, v/v/v/v) at a flow rate of 1.0 ml min(-1) on a LiChrospher RP-18 column with UV (254 nm) detection has been developed for the separation of sulfadoxine and its metabolite N-acetyl sulfadoxine in plasma. No interferences due to endogenous compounds or common antimalarial drugs were noticed. The limit of detection for sulfadoxine and N-acetyl sulfadoxine was 0.01 microg ml(-1) with a signal-to-noise ratio of 5:1 while the limit of quantification was 2.5 microg ml(-1). Intra-day mean relative standard deviations (RSD's) for sulfadoxine and N-acetyl sulfadoxine were 2.6 and 2.8%, respectively, while mean inter-day RSD's for sulfadoxine and N-acetyl sulfadoxine were 2.4 and 2.8%, respectively. Extraction recoveries averaged 90.6% for sulfadoxine and 86.9% for N-acetyl sulfadoxine. The method was applied for the assay of sulfadoxine and its metabolite N-acetyl sulfadoxine in plasma from Plasmodium falciparum malaria patients. Mean plasma sulfadoxine concentrations on day 2 (51 h) from samples collected from sensitive and resistant P. falciparum patients treated with three tablets of Fansidar were 62.8 and 60.5 microg ml(-1), respectively. Mean ratio of N-acetyl sulfadoxine to sulfadoxine was 9.1% for responders and 13.9% for non-responders which revealed that higher amounts of the metabolite N-acetyl sulfadoxine were present in non-responders. The method described should find an application in the therapeutic monitoring of malaria patients.     

Differential inter- and intra-specific defense induction in Lupinus by Myzus persicae feeding

Experiments were conducted to investigate the potential induction of plant defenses by Myzus persicae Sulzer (Homoptera: Aphididae) feeding on five lupin, Lupinus spp. (Leguminosae), varieties with well‐characterized levels of aphid resistance. Myzus persicae feeding on L. angustifolius and L. luteus varieties induced genotype‐specific changes in their host that were not consistent with the level of aphid resistance or the plant species. The plant responses were systemically detected by apterous and alate forms of the aphids. Chemical assays revealed no induction of oxidizing enzyme (catalase, peroxidase, or polyphenol oxidase) activity, serine or cystein proteinase inhibitors, or soluble phenolics in any of the five varieties tested following 3 days of feeding by 10 or 30 aphids. However, there were significant differences among the five lupin varieties in the levels of peroxidase and polyphenol oxidase activity, proteinase inhibitors, and soluble phenolics.     

The atmospheric chemistry of trace gases and particulate matter emitted by different land uses in Borneo

We report measurements of atmospheric composition over a tropical rainforest and over a nearby oil palm plantation in Sabah, Borneo. The primary vegetation in each of the two landscapes emits very different amounts and kinds of volatile organic compounds (VOCs), resulting in distinctive VOC fingerprints in the atmospheric boundary layer for both landscapes. VOCs over the Borneo rainforest are dominated by isoprene and its oxidation products, with a significant additional contribution from monoterpenes. Rather than consuming the main atmospheric oxidant, OH, these high concentrations of VOCs appear to maintain OH, as has been observed previously over Amazonia. The boundary-layer characteristics and mixing ratios of VOCs observed over the Borneo rainforest are different to those measured previously over Amazonia. Compared with the Bornean rainforest, air over the oil palm plantation contains much more isoprene, monoterpenes are relatively less important, and the flower scent, estragole, is prominent. Concentrations of nitrogen oxides are greater above the agro-industrial oil palm landscape than over the rainforest, and this leads to changes in some secondary pollutant mixing ratios (but not, currently, differences in ozone). Secondary organic aerosol over both landscapes shows a significant contribution from isoprene. Primary biological aerosol dominates the super-micrometre aerosol over the rainforest and is likely to be sensitive to land-use change, since the fungal source of the bioaerosol is closely linked to above-ground biodiversity.     

Separation of mesophyll protoplasts and bundle sheath cells from maize leaves for photosynthetic studies

Mesophyll protoplasts and bundle sheath strands of maize (Zea mays L.) leaves have been isolated by enzymatic digestion with cellulase. Mesophyll protoplasts, enzymatically released from maize leaf segments, were further purified by use of a polyethylene glycol-dextran liquid-liquid two phase system. Bundle sheath strands released from the leaf segments were isolated using filtration techniques. Light and electron microscopy show separation of the mesophyll cell protoplasts from bundle sheath strands. Two varieties of maize isolated mesophyll protoplasts had chlorophyll a/b ratios of 3.1 and 3.3, whereas isolated bundle sheath strands had chlorophyll a/b ratios of 6.2 and 6.6. Based on the chlorophyll a/b ratios in mesophyll protoplasts, bundle sheath cells, and whole leaf extracts, approximately 60% of the chlorophyll in the maize leaves would be in mesophyll cells and 40% in bundle sheath cells. The purity of the preparations was also evident from the exclusive localization of phosphopyruvate carboxylase (EC 4.1.1.31) and NADP-dependent malate dehydrogenase (EC 1.1.1) in mesophyll cells and ribulose 1,5-diphosphate carboxylase (EC 4.1.1.39), phosphoribulokinase (EC 2.7.1.19), and “malic enzyme” (EC 1.1.1.40) in bundle sheath cells. NADP-glyceraldehyde 3-phosphate dehydrogenase (EC 1.2.1.13) was found in both mesophyll and bundle sheath cells, while ribose 5-phosphate isomerase (EC 5.3.1.6) was primarily found in bundle sheath cells. In comparison to the enzyme activities in the whole leaf extract, there was about 90% recovery of the mesophyll enzymes and 65% recovery of the bundle sheath enzymes in the cellular preparations.     

Regulation of glutathione S-transferases of Zea mays in plants and cell cultures

An antiserum to glutathione S-transferase (EC 2.5.1.18) from maize (Zea mays L.) responsible for herbicide detoxification has been raised in rabbit. The antiserum was specific to the M_r 26000 subunit of the enzyme from maize seedlings and suspension-cultured cells, and recognized the isoenzymes active toward both atrazine and metolachlor. When plants were treated for 24 h with the herbicide antidote N,N-diallyl-2-2-dich-loroacetamide (DDCA), enzyme activities toward metolachlor were doubled in the roots and this was associated with a 70% increase in immunodetectable protein. Translation of polysomal RNA in vitro showed that the increase in the transferase in root tissue was brought about by a ninefold increase in mRNA activity encoding the enzyme. Treatment of suspension-cultured cells with cinnamic acid, metolachlor and DDCA raised enzyme activities but did not increase synthesis of glutathione S-transferase. In cultured maize cells, enzyme synthesis was maximal in mid-logarithmic phase, coinciding with the highest levels of enzyme activity. When callus cultures were established from the shoots of a maize line known to conjugate chloro-s-triazines, enzyme activity towards atrazine was lost during primary dedifferentiation. However, levels of total immunodetectable enzyme and activity toward metolachlor were increased in cultured cells compared with the parent shoot tissue.     

Spinal cord regeneration: Lessons for mammals from non‐mammalian vertebrates

Unlike mammals, regenerative model organisms such as amphibians and fish are capable of spinal cord regeneration after injury. Certain key differences between regenerative and nonregenerative organisms have been suggested as involved in promoting this process, such as the capacity for neurogenesis and axonal regeneration, which appear to be facilitated by favorable astroglial, inflammatory and immune responses. These traits provide a regenerative‐permissive environment that the mammalian spinal cord appears to be lacking. Evidence for the regenerative nonpermissive environment in mammals is given by the fact that they possess neural stem/progenitor cells, which transplanted into permissive environments are able to give rise to new neurons, whereas in the nonpermissive spinal cord they are unable to do so. We discuss the traits that are favorable for regeneration, comparing what happens in mammals with each regenerative organism, aiming to describe and identify the key differences that allow regeneration. This comparison should lead us toward finding how to promote regeneration in organisms that are unable to do so. genesis 51:529–544. © 2013 Wiley Periodicals, Inc.     

Mouse models of rhinovirus-induced disease and exacerbation of allergic airway inflammation

Rhinoviruses cause serious morbidity and mortality as the major etiological agents of asthma exacerbations and the common cold. A major obstacle to understanding disease pathogenesis and to the development of effective therapies has been the lack of a small-animal model for rhinovirus infection. Of the 100 known rhinovirus serotypes, 90% (the major group) use human intercellular adhesion molecule-1 (ICAM-1) as their cellular receptor and do not bind mouse ICAM-1; the remaining 10% (the minor group) use a member of the low-density lipoprotein receptor family and can bind the mouse counterpart. Here we describe three novel mouse models of rhinovirus infection: minor-group rhinovirus infection of BALB/c mice, major-group rhinovirus infection of transgenic BALB/c mice expressing a mouse-human ICAM-1 chimera and rhinovirus-induced exacerbation of allergic airway inflammation. These models have features similar to those observed in rhinovirus infection in humans, including augmentation of allergic airway inflammation, and will be useful in the development of future therapies for colds and asthma exacerbations.