Search

Clubroot caused by Plasmodiophora brassicae is an important disease of brassica crops. The use of vital stains to determine the viability of P. brassicae resting spores can provide useful information regarding spore longevity, inoculum potential, or the efficacy of antimicrobial treatments. Evans blue is one example of a vital stain that has been reported to differentially stain viable and nonviable resting spores. Some previously published protocols using Evans blue to stain P. brassicae resting spores have not provided accurate or consistent results. In this study, we modified the Evans blue method by increasing the staining time to 8 h or more and evaluated P. brassicae resting spores after heat treatment at various combinations of temperature and time. Extending staining times significantly increased the numbers of stained resting spores up to 7 h, after which the numbers of stained spores did not change significantly (R2 = 96.88; P ≤ 0.001). The accuracy of the modified method to discriminate viable and nonviable spores was evaluated in repeated experiments and by comparing the staining data with those derived from inoculation assays and propidium monoazide quantitative PCR (qPCR). The results demonstrated that the modified Evans blue staining method improved the accuracy and consistency of measurement of P. brassicae resting spore viability. Additionally, it was equivalent to the qPCR method for differentiating viable and nonviable spores (R2 = 99.84; P ≤ 0.001) and confirmed in canola infection bioassays.

The goal of this project was to validate the functional relevance and utility of mucus produced by an in vitro intestinal cell culture model. This is facilitated by the need to physiologically replicate both healthy and abnormal mucus conditions from native intestinal tissue, where mucus properties have been connected to intestinal disease models. Mucus harvested from colonic cell cultures derived from healthy donors was compared to mucus collected from surgically resected, noninflamed transverse colon tissue. The rheological and biochemical properties of these mucus samples were compared using oscillational rheometry, particle-tracking microrheology, multiangle laser light scattering, refractometry, and immunohistochemical imaging. An air-liquid interface culture of primary human colonic epithelial cells generated a continuous monolayer with an attached mucus layer that displayed increasing weight percent (wt%) of solids over 1 week (1.3 ± 0.5% at 2 days vs. 2.4 ± 0.3% at 7 days). The full range of mucus concentrations (0.9–3.3%) observed during culture was comparable to that displayed by ex vivo mucus (1.3–1.9%). Bulk rheological measurements displayed similar wt%-based complex viscosities between in vitro and ex vivo mucus, with the complex viscosity of both systems increasing with wt% of solids. Particle-tracking microrheology showed higher complex viscosities for ex vivo mucus samples than in vitro mucus which was explained by a greater fraction of water present in in vitro mucus than ex vivo, i.e., in vitro mucus is more heterogeneous than ex vivo. Refractometry, multiangle laser light scattering, and immunostaining showed increased mucus complex size in ex vivo mucus compared with in vitro mucus, which may have been due to the admixture of mucus and cellular debris during ex vivo mucus collection. The air-liquid interface culture system produced intestinal mucus with similar composition and rheology to native human gut mucus, providing a platform to analyze pathological differences in intestinal mucus.

Sutherlandia frutescens (L) R. Br. contains several essential, bioactive compounds with clinically proven pharmacological activities. Sutherlandia is prescribed for people with tuberculosis but it is still not known what compounds in this plant act against Mycobacterium tuberculosis and its mode of action. This study is aimed at determining if S. frutescens extracts contain antimycobacterial compounds. Aerial parts of S. frutescens were dried, ground and extracted with ethanol, dichloromethane: methanol 1:1 (v/v) and water. The chemical profiling was done using high-performance liquid chromatography-mass spectroscopy (HPLC-MS) and thin layer chromatography (TLC). TLC plates were developed in butanol:acetic acid:water (BAW) to the ratio of 21:6:3; chloroform:methanol:water:formic acid (CMWF1) [60:15:2:1] and (CMWF2) [21:9:1:0.3]. Qualitative antioxidant activity was done, using 2.2-diphenylpacryl-1-hydrazyl (DPPH). Antimycobacterial activity of the plant extracts was evaluated, using micro-dilution and bioautographic methods against Mycobacterium smegmatis. Low antimycobacterial activity against M. smegmatis was observed on the bioautograms. The ethanol extracts contained more compounds compared to water extracts on HPLC-MS chromatographic profiles. The average Minimum Inhibitory Concentration (MIC) values for all the extracts were 0.61 mg/mL units and the DCM:MeOH (1:1) extract had the lowest MIC value of 0.28 mg/mL. The results showed that the plant could be further explored for possible antimycobacterial agents. Low activity was observed, possibly due to low replication of bacilli and non-replicating organisms. The study provides preliminary scientific validation of the traditional medicinal use of this plant. Further studies are required to identify the bioactive compounds in the DCM:MeOH 1:1 extract which showed significant antimycobacterial activities. Research correlation: This article is the original version, of which an Afrikaans translation was made available to provide access to a larger readership, available here: https://doi.org/10.4102/satnt.v36i1.1494

Susceptibility of biofilms of Clavibacter michiganensis subsp. sepedonicus, the causal agent of bacterial ring rot of potato, to three common agricultural disinfectants was tested. The MBECTM assay device was used to evaluate optimum parameters for growing artificial biofilms. These conditions were determined to be 7 days of growth at 23°C in a yeast extract-glucose-mineral salts medium. As expected, the bacteria in the biofilm state were more resistant to disinfection by chemical treatment with sodium hypochlorite, quaternary ammonium, and hydrogen peroxide when compared with planktonic cells. Artificial biofilms were also grown on five different surface materials typically found in commercial potato storage facilities (concrete, mild steel, rubber, polycarbonate and wood) using the BESTTM assay device to test the effect of surface type on biofilm susceptibility to disinfection. Sodium hypochlorite was the most effective disinfectant on the wood surface and hydrogen peroxide was best on the mild ...

Background Sutherlandia frutescens (L) R.Br. is one of traditional herbal medicines that formed the basis of primary health care systems since the earliest days and is still widely used. Sutherlandia is prescribed for people with tuberculosis (TB), but is still not known which compound(s) acts against M. tuberculosis and its mode of action. The aim of this study was to identify and isolate antimycobacterial compounds from S. frutescens extracts against shikimate kinase, a drug target for M. tuberculosis. Methods S. frutescens were dried, ground and extracted with ethanol, dichloromethane: methanol and water. Fractionation and separation of compounds was done with column chromatography. Chromatograms were developed in butanol/acetic acid/water (BAW) [21:6:3]; chloroform/methanol/water/formic acid (CMWF1) [60:15:2:1] and (CMWF2) [21:9:1:0.3]. Separation and isolation of active compounds were done using preparative HPLC. The activity of the plant extracts were also screened against shikimate kinase enzyme (MtbSK) using the MtbSK inhibition assay. Results The DCM: MeOH (1:1) extract showed a high percentage inhibition (with an IC50 of 0.1 μg/ml) of MtbSK and the purified inhibitor was an Alpha-Linolenic Acid (ALA) compound and it had a significant IC50 of 3.7 μg/ml. Conclusions This study demonstrated that ALA from S. frustescens is an inhibitor of shikimate kinase a good drug target for M. tuberculosis.

Leaf extracts of Senna italica, Ricinus communis, Lantana camara, Lippia javanica and Ziziphus mucronata were screened for biological activity against bacteria which infect wounds. The leaves were extracted using different solvents of varying polarity (hexane, dichloromethane, acetone and methanol). Phytochemical analyses of the extracts were performed using thin layer chromatography (TLC). The extracts were loaded on TLC plates and developed in three solvent systems that is benzene/ethanol /ammonium solution (BEA), chloroform/ethyl acetate/formic acid (CEF) and ethyl acetate/methanol /water (EMW). Antibacterial activity of the plants was evaluated using micro-dilution and bioautography methods. The test organisms used were Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Enterococcus faecalis. Acetone extracts were chosen for antioxidant activity. Methanol was the best extractant, followed by acetone and dichloromethane (DCM). In the phytochemical analysis, more compounds were observed on BEA, followed by EMW and CEF plates. Lantana camara had no activity against any of the bacteria used. P. aeruginosa was the most resistant bacterium with only two plants active against it. E. faecalis and E. coli were sensitive to the extracts. More antibacterial compounds were observed on BEA plates against all the test bacteria in bioautographic method. The Rf values calculated from bioautography indicated that the selected plants have different active compounds. The most active compounds were from S. italica and Z. mucronata. BEA and EMW plates had good antioxidant activity. No antioxidant activity was observed on the CEF plate. Most extracts were active against wound pathogens; their application on the wound area may prevent infection. Further studies are required to identify the active compounds in the plant extracts which showed significant anti-bacterial activities.Key words: Thin layer chromatography (TLC), plant extract, bacteria.

J. Neurochem. (2011) 119, 604–616. Abstract Fatty acids such as eicosapentaenoic acid (EPA) have been shown to be beneficial for neurological function and human health. It is widely thought that oxidation products of EPA are responsible for biological activity, although the specific EPA peroxidation product(s) which exert these responses have not yet been identified. In this work we provide the first evidence that the synthesized representative cyclopentenone IsoP, 15-A3t-IsoP, serves as a potent inhibitor of lipopolysaccharide-stimulated macrophage activation. The anti-inflammatory activities of 15-A3t-IsoP were observed in response not only to lipopolysaccharide, but also to tumor necrosis factor alpha and IL-1b stimulation. Subsequently, this response blocked the ability of these compounds to stimulate nuclear factor kappa b (NFκB) activation and production of proinflammatory cytokines. The bioactivity of 15-A3t-IsoP was shown to be dependent upon an unsaturated carbonyl residue which transiently adducts to free thiols. Site directed mutagenesis of the redox sensitive C179 site of the Ikappa kinase beta subunit, blocked the biological activity of 15-A3t-IsoP and NFκB activation. The vasoprotective potential of 15-A3t-IsoP was underscored by the ability of this compound to block oxidized lipid accumulation, a critical step in foam cell transformation and atherosclerotic plaque formation. Taken together, these are the first data identifying the biological activity of a specific product of EPA peroxidation, which is formed in abundance in vivo. The clear mechanism linking 15-A3t-IsoP to redox control of NFκB transcription, and the compound’s ability to block foam cell transformation suggest that 15-A3t-IsoP provides a unique and potent tool to provide vaso- and cytoprotection under conditions of oxidative stress.

Lipid peroxidation of docosahexaenoic (22:6; n-3) acid (DHA) is elevated in the CNS in patients with Alzheimer's disease and in animal models of seizure and ethanol withdrawal. One product of DHA oxidation is trans-4-hydroxy-2-hexenal (HHE), a six carbon analog of the n-6 fatty acid derived trans-4-hydroxy-2-nonenal (HNE). In this work, we studied the neurotoxic potential of HHE. HHE and HNE were toxic to primary cultures of cerebral cortical neurons with LD(50)'s of 23 and 18 micromol/L, respectively. Toxicity was prevented by the addition of thiol scavengers. HHE and HNE depleted neuronal GSH content identically with depletion observed with 10 micromol/L of either compound. Using an antibody raised against HHE-protein adducts, we show that HHE modified specific proteins of 75, 50, and 45 kDa in concentration- and time-dependent manners. The time-dependent formation of HHE differed from that of F4-neuroprostanes following in vitro DHA oxidation likely as a result of the different oxidation pathways involved. Using purified mitochondrial aldehyde dehydrogenase ALDH5A, we found that HHE was oxidized 6.5-fold less efficiently than HNE. Our data demonstrate that HHE and HNE have similarities but also differences in their neurotoxic mechanisms and metabolism.

Mycosphaerella blight (Mycosphaerella pinodes) occurs throughout western Canada and can severely reduce field pea (Pisum sativum) seed yield. Field trials were conducted at two sites (Edmonton, AB, and Morden, MB) from 2001 to 2003 to assess the impact of seeding rate and seeding depth on blight severity. Mycosphaerella blight severity in the canopy was greater at higher seeding rates; treatments seeded at 30 plants m-2 had lower levels of disease than those seeded at more than 100 seeds m-2. However, yield potential was reduced at low seeding densities. Depth of seeding did not affect seedling density, disease severity, yield or final seed weight. In addition, field trials were conducted at Edmonton to quantify yield losses associated with mycosphaerella blight in Alberta. In trials inoculated with M. pinodes, application of a foliar fungicide (chlorothalonil) increased yield by about 20% over the unprotected control. Key words: Pisum, Mycosphaerella, fungicide, crop management, yield loss

Fusarium root rot (Fusarium spp.) is one of the most important seedling diseases of coneflower (Echinacea spp.) in Alberta greenhouses. Effects of microbial antagonists (Trichoderma spp.) and fungicides, including difenoconazole, fludioxonil, and a mixture of fludioxonil, metalaxyl and difenoconazole, on the management of this disease, were investigated in Alberta. Twenty Trichoderma isolates demonstrated antagonistic activity to Fusarium in agar plate bioassays, with inhibition rates ranging from 44 to 65%. Some Trichoderma isolates significantly ( p < 0.05) reduced disease incidence and severity on seedlings in greenhouse experiments. An in vitro bioassay indicated that difenoconazole and the mixture equally inhibited the growth of both Fusarium and Trichoderma, but, while fludioxonil strongly inhibited the growth of Fusarium, it had little effect on Trichoderma, according to the dose--response models developed ( p < 0.01, R2= 0.902-0.998). Two Trichoderma isolates, T1 and T13 were applied singly or in combination with a low rate of fludioxonil in greenhouse evaluations. The results suggested that fludioxonil and Trichoderma could be integrated into a disease management program for fusarium root rot in coneflower.

Rhizoctonia solani Kühn, a prevalent fungal pathogen in cultivated prairie soils, can be an important factor affecting seedling establishment of chickpea (Cicer arietinum L.). Studies were undertaken to determine the impact of different soil conditions on seedling establishment, development of root rot, and productivity of desi (Tyson) and kabuli (Sanford) chickpea plants sown in the presence of R. solani AG-4. The impact of soil and air temperatures and seeding depth was studied under controlled conditions, and the influence of seeding date was investigated at three field sites. The host responded to warm soils by increasing its growth rate, and the pathogen by increasing its virulence. The kabuli cultivar, Sanford, showed greater susceptibility to root rot caused by R. solani than the desi cultivar, Tyson. Root rot and shoot infection levels increased with soil temperature for both cultivars, but reached maximum values at substantially lower temperatures for Sanford. Shoot biomass of infected treatments for this cultivar was substantially lower than the controls, while the biomass of Tyson was affected to a lesser degree. Air temperatures of 17/3°C day/night allowed relatively unhindered plant growth, even of the more susceptible cultivar, Sanford, in the presence of R. solani, while warmer and cooler temperatures resulted in high mortality and diminished plant growth in surviving plants. Seedling emergence and seedling dry weight were greater at a seeding depth of 2 cm than at 5 cm for seedlings grown in infested soil. In inoculated field plots, seedling emergence was greatest in treatments seeded in late May to early June compared those seeded in early or mid-May; in noninoculated treatments, both emergence and yield were lower in treatments seeded in late May than at the earlier seeding dates. Seeding date did not affect the occurrence of root rot. Key words: Rhizoctonia solani, Cicer arietinum, seed treatment, seeding date, soil temperature, air temperature, seeding depth

The aim of this study was to produce a secreted, heterologously expressed Phanerochaete chrysosporium cellobiohydrolase (CBHI.1) protein that required no in vitro chemical refolding and to investigate the cellulolytic activity of the clone expressing the glutathione S-transferase (GST) fused CBHI.1 protein. Plate enzyme activity screening of E. coli cells transformed with pGEXcbhI.1 vector on carboxy-methyl-cellulose (CMC) produced several clones which produced clearing zones on CMC when induced. A randomly selected representative pGEXcbhI.1 clone produced hydrolysis on both Avicel and CMC when induced. Crude protein extracts obtained from the induced pGEXcbhI.1 clone exhibited time dependent enzymatic activity against both CMC and Avicel. Key words : Phanerochaete chrysosporium, cellobiohydrolase, cellulase activity, heterologous expression. African Journal of Biotechnology Vol.2(9) 2003: 296-300

The hypocretins (orexins) are recently described hypothalamic neuropeptides thought to have an important role in the regulation of sleep and arousal states1. Their discovery was reported independently by two groups using different techniques. de Lecea et al.2 identified the pro-hormone pre-prohypocretin, and its peptide products hypocretin-1 (Hcrt-1) and hypocretin-2 (Hcrt-2), by nucleotide sequencing. The discovery of the orexins, orexin-A (Orx-A) and orexin-B (Orx-B), was reported almost simultaneously by Sakurai et al.3 who used the technique of orphan receptor cloning. The terms orexin and hypocretin are synonymous and in this article we will use hypocretin (Hcrt). The finding that cerebrospinal fluid (CSF) levels of these peptides were abnormal in patients with narcolepsy has stimulated research on the potential role of these peptides in human disease. We present here an overview of the pertinent findings from animal studies and a review of the published data from human studies, with a particular emphasis on narcolepsy. Finally, we consider the possible roles of these peptides in neurological and psychiatric disorders.

Invasion by grasses and weedy species occurs when plant density in alfalfa fields falls below critical levels. Several soil-borne fungal pathogens can reduce stand density in alfalfa by impeding seedling establishment and by killing older plants weakened by other stresses. Surveys of alfalfa fields were conducted in 1997, and pathogenic fungi from rotted roots were isolated and identified. Isolates of selected pathogens were applied with the seed in field trials to assess the impact of fertilizer and seeding system (conventional vs. sod-seeding, spring vs. dormant-fall seeding) on seedling emergence and subsequent productivity when disease pressure was high. The impact of various fungicide seed treatments was also assessed. Seed treatment improved seedling emergence and initial forage productivity in one of three trials; however, it had little effect on long-term forage yield. Addition of sulphur fertilizer had little effect on seedling emergence or survival, but improved forage productivity at all three trial sites. Sod-seeded plots suffered more winterkill and were less vigorous than plots seeded into a tilled seedbed. Seedling emergence was lower when seedlings were planted in the fall than in the spring. However, fall-seeded treatments showed a less adverse response to inoculum treatments and, in some cases, these seedlings were able to take advantage of early-season moisture to produce higher yields than their spring-seeded counterparts. Key words: Medicago, Fusarium, Pythium, Phoma, fungicide, seed treatment, fertilizer, tillage

In tomato, Ve is implicated in race-specific resistance to infection by Verticillium species causing crop disease. Characterization of the Ve locus involved positional cloning and isolation of two closely linked inverted genes. Expression of individual Ve genes in susceptible potato plants conferred resistance to an aggressive race 1 isolate of Verticillium albo-atrum . The deduced primary structure of Ve 1 and Ve 2 included a hydrophobic N-terminal signal peptide, leucine-rich repeats containing 28 or 35 potential glycosylation sites, a hydrophobic membrane-spanning domain, and a C-terminal domain with the mammalian E/DXXXLφ or YXXφ endocytosis signals (φ is an amino acid with a hydrophobic side chain). A leucine zipper-like sequence occurs in the hydrophobic N-terminal signal peptide of Ve 1 and a Pro-Glu-Ser-Thr (PEST)-like sequence resides in the C-terminal domain of Ve 2. These structures suggest that the Ve genes encode a class of cell-surface glycoproteins with receptor-mediated endocytosis-like signals and leucine zipper or PEST sequences.

Early seeding of lentil is necessary on the northern prairies to ensure that the crop has time to mature. However, planting into cold soils in spring results in slow germination, which may predispose seedlings to infection by soil-borne pathogens. In a controlled-environment study of the impact of temperature on infection of lentil seedlings (cv. Eston) byFusarium avenaceum, root rot symptoms were most severe at warm temperatures (20° to 27.5 °C) and declined in warmer or cooler soils. Field plots were seeded on three dates, which were spaced about 2 wk apart between early May and early June in four station years. Seedling emergence was most consistent and seed yield was highest in three of four sites at the second seeding date. Emergence and yield were substantially lower for the latest seeding date. Inoculation with F. avenaceum reduced establishment and seed yield. Seed treatment with Crown (thiabendazole and carbathiin) improved seedling survival, reduced root rot severity and increased seed yield relative to the inoculated control. Vitaflo-280 (thiram and carbathiin) also improved establishment and yield, but the effect was not as strong or consistent. Treatment with Raxil (tebuconazole) and Apron (metalaxyl) had no effect. The pathogenicity of aggressive isolates of F. avenaceum from lentil on a range of crop species was evaluated. All crops were susceptible to some degree, which indicates that the pathogen, once established, is likely to persist in a field for some time. This study demonstrated that early planting was required for maximum yield, that certain isolates of F. avenaceum were pathogenic on a wide range of hosts, and that seed treatment can be used to minimize losses from seedling blight and root rot in lentil. Key words: Lentil (Lens culinaris Medikus), Fusarium avenaceum, root rot, seeding date, thiabendazole, carbathiin, thiram, tebuconazole

Greenhouse studies showed that root inoculation had significant effects on sclerotinia blight (Sclerotinia sclerotiorum) of coneflower (Echinacea sp.). Seedling wilt and root rot symptoms caused by S. sclerotiorum were most severe when inoculum was placed in direct contact with seedling roots, and diminished as the distance of the inoculum from the roots increased. When colonized agar disks, colonized oat grains and sclerotia as inoculum sources were evaluated on E. angustifolia, grain inoculum was the most virulent and sclerotia the least. An in vitro bioassay was conducted, and a logistic dose-response model was developed for the fungicides benomyl, vinclozolin, iprodione and dicloran. The first three fungicides were further evaluated in greenhouse experiments. Benomyl was the most effective in controlling S. sclerotiorum in both bioassay and greenhouse evaluations. The same three fungicides were evaluated in two field experiments in Alberta, where all were effective in reducing disease incidence. Key words: Echinacea sp., Sclerotinia sclerotiorum, dose-response model

Processing of vanadiferous slags through the pyrometallurgical process route appears to offer advantages both in terms of ferroalloy production and in the potential for efficient vanadium recovery from hot metal. In order to investigate the effect of slag composition on the phase distribution of vanadium, a series of laboratory smelting experiments was carried out. The effect of basicity adjustments on the slag/metal distribution of iron, vanadium, and manganese was investigated using carbon and FeSi as a reductant. A simulation of the final stage of slag reduction was also carried out to determine the efficiency of vanadium recovery during metallothermic smelting using aluminum and FeSi.

Internal fruit rot, caused by Fusarium lactis, is an important disease of sweet pepper (Capsicum annuum) in Canadian greenhouses. Production of the mycotoxins fumonisin B₁ (FB₁), moniliformin (MON) and beauvericin (BEA) by F. lactis (17 isolates) and the related species F. proliferatum (three isolates) and F. verticillioides (one isolate), which are also associated with internal fruit rot, was evaluated on rice medium. All 21 isolates examined were found to produce BEA, at concentrations ranging from 13.28 to 1674.60 ppm, while 13 of 17 F. lactis isolates and two of three F. proliferatum isolates produced MON (0.23 to 181.85 ppm). Only one isolate of F. lactis produced detectable levels of FB₁ in culture, whereas all three F. proliferatum isolates and the F. verticilloides isolate produced this mycotoxin (0.28 to 314 ppm). Production of FB₁, MON and BEA was also evaluated in inoculated pepper fruits showing mild or severe symptoms of infection. FB₁ could be detected in both lightly and heavily diseased fruit tissue after inoculation with F. lactis, F. proliferatum or F. verticilloides, at concentrations ranging from 0.61 to 8.04 ppm. BEA was also detected in lightly and heavily diseased fruit tissue inoculated with F. lactis, as well as in heavily diseased tissue inoculated with F. proliferatum (3.00 to 19.43 ppm), but not in tissue inoculated with F. verticilloides. MON was detected in all tissues inoculated with F. proliferatum or F. verticilloides, and in heavily diseased tissue inoculated with F. lactis (0.03 to 0.27 ppm). The three mycotoxins were also found in naturally infected sweet pepper fruits exhibiting symptoms of internal fruit rot and collected from a commercial greenhouse. The production of MON, BEA and FB₁ alone or in combination by isolates of F. lactis suggests that development of internal fruit rot of sweet pepper is an important food safety concern, and that every effort should be made to cull infected fruit before it makes it to market.

Lipids from the paracloacal glands of adult Chinese alligators (Alligator sinensis) were analyzed by gas chromatography/mass spectrometry. Acetates, aliphatic alcohols, free fatty acids and waxes consisting primarily of hexadecanoates were indicated in the secretions of males and females. Cholesterol, a diterpene hydrocarbon, and a diterpene ketone were detected in secretions of males but not in those of females. Lipids identified in the paracloacal secretions ofA. sinensis are compared with those reported from the American alligator and other crocodilians.

Fifteen plant species were collected from the Nelspruit Botanical Garden based on a list of plants provided by Phytomedicine Programme at the University of Pretoria and their ethnopharmacological information. Hexane, dichloromethane (DCM), acetone and methanolic extracts were screened forantimycobacterial activity against Mycobacterium smegmatis. The acetone extract of Milletia stulhimannii was the most active, showing activity against Mycobacterium smegmatis with minimum inhibitory concentration (MIC) value of 0.13 mg/ml. Acetone extracts for all plants had lower MIC values ranging between 0.11-1.25 mg/ml against M. smegmatis. Milletia stulhimannii, Albizia gummifera, Xanthocercis zambesiaca and Barringtonia racemosa have shown great potential as anti-tuberculosis agents. They were active against M. smegmatis with average MIC values of acetone extracts of 0.13 mg/ml.Keywords: Tuberculosis, Antimycobacterial activity, Milletia stulhimannii, Minimum inhibitory concentration

Senna italica, a member of the Fabaceae family (subfamily Caesalpinaceae), is widely used traditionally to treat a number of disease conditions, such as sexually transmitted diseases and some forms of intestinal complications. The roots of Senna italica were collected from Zebediela subregion, Limpopo province (S.A), powdered and extracted with acetone by cold/shaking extraction method. The phytochemical composition of the extract was determined by thin layer chromatography (TLC). The chromatograms were visualised with vanillin-sulphuric acid and p-anisaldehyde reagents. The total phenolic content of the extract was determined by Folin-Ciocalteu method and expressed as TAE/g dry weight. The extract was assayed for the in vitro anticancer activity using Jurkat T cells, antioxidant activity using DPPH assay and antibacterial activity by bioautographic method and the microtitre plate method. The acetone extract of the roots of Senna italica inhibited the growth of Jurkat T cells in a dose- and time-dependent manner. The extract also had free radical scavenging activity as well as reasonable antibacterial activity against Pseudomonas aeruginosa, Enterococcus faecalis, Escherichia coli and Staphylococcus aureus with MICs ranging from 0,08 to 0.16 mg/ml in the same order as ampicillin the positive control. The biological activities observed in the acetone extract validated the ethnomedicinal use of Senna italica.

Histamine has been shown to mediate features of pulmonary allergic reactions including increased tracheobronchial blood flow. To determine whether the increase in blood flow was due to stimulation of H1- or H2-histamine receptors, we gave histamine base (0.1 micrograms/kg iv) or histamine dihydrochloride as an aerosol (10 breaths of 0.5% “low dose” or 5% “high dose”) before and after H1- or H2-receptor antagonists. Blood velocity in the common bronchial branch of the bronchoesophageal artery (Vbr) was continuously measured using a chronically implanted Doppler flow probe. Pretreatment with H2-receptor antagonists cimetidine, ranitidine, or metiamide did not affect the increase in Vbr induced by intravenous histamine [106 +/- 45% (SD)]. Addition of the H1-receptor antagonists diphenhydramine or chlorpheniramine, however, reduced the Vbr response to 16 +/- 22, 21 +/- 28, 23 +/- 23, and 37 +/- 32% of the unblocked responses (P less than 0.05) when intravenous histamine was given at 3, 10, 20, and 30 min, respectively, after the H1 antagonist. At 40, 50, and 60 min the H1-receptor blockade appeared to attenuate, but subsequent continuous infusion of chlorpheniramine (2 mg.kg-1.min-1) then blocked the histamine response for 60 min. Low-dose histamine aerosol did not change mean arterial or pulmonary arterial pressures, cardiac output, or arterial blood gases but increased Vbr transiently from 15.2 +/- 3.4 to 37.6 +/- 8.4 (SE) cm/s. After chlorpheniramine, the Vbr response to histamine, 16.3 +/- 2.2 to 22.6 +/- 3.6 cm/s, was significantly reduced (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Objective.To investigate the marked increase noted over an 8-month period in the number ofLegionella pneumophilaisolates recovered from bronchoalveolar lavage fluid specimens obtained during bronchoscopy in our healthcare system.Setting.Bronchoscopy suite that serves a 580-bed tertiary care center and a large, multisite, faculty practice plan with approximately 2 million outpatient visits per year.Methods.Cultures of environmental specimens from the bronchoscopy suite were performed, including samples from the air and water filters, bronchoscopes, and the ice machine, with the aim of identifyingLegionellaspecies. Specimens were filtered and acid-treated and then inoculated on buffered charcoal yeast extract agar. Serogrouping was performed on all isolates recovered from patient and environmental samples.Results.AUL. pneumophilaisolates recovered from patients were serogroup 8, a serogroup that is not usually recovered in our facility. An epidemiologic investigation of the bronchoscopy suite revealed the ice machine to be contaminated withL. pneumophilaserogroup 8. Patients were exposed to the organism as a result of a recently adopted practice in the bronchoscopy suite that involved directly immersing uncapped syringes of sterile saline in contaminated ice baths during the procedures. At least 1 patient was ill as a result of the pseudo-outbreak. Molecular typing of isolates recovered from patient and environmental samples revealed that the isolates were indistinguishable.Conclusions.Extensive cleaning of the ice machine and replacement of the machine's water filter ended the pseudo-outbreak. This episode emphasizes the importance of using aseptic technique when performing invasive procedures, such as bronchoscopies. It also demonstrates the importance of reviewing procedures in all patient areas to ensure compliance with facility policies for providing a safe patient environment.

A high-NaCl diet induces renal medullary cyclooxygenase (COX)2 expression, and selective intramedullary infusion of a COX2 inhibitor increases blood pressure in rats on a high-salt diet. The present study characterized the specific prostanoid contributing to the antihypertensive effect of COX2. C57BL/6J mice placed on a high-NaCl diet exhibited increased medullary COX2 and microsomal prostaglandin E synthase1 (mPGES1) expression as determined by immunoblot and real-time PCR. Cytosolic prostaglandin E synthase and prostacyclin synthase were not induced by the high-salt diet. Immunofluorescence showed mPGES1 in collecting ducts and interstitial cells. High salt increased renal medullary PGE2as determined by gas chromatography/negative ion chemical ionization mass spectrometry. The effect of direct intramedullary PGE2infusion was examined in anesthetized uninephrectomized mice. Intramedullary PGE2infusion (10 ng/h) increased urine volume (from 3.3 ± 0.6 to 9.5 ± 1.6 μl/min) and urine sodium excretion (0.11 ± 0.02 to 0.32 ± 0.05 μeq/min). To determine which E-prostanoid (EP) receptor(s) mediated PGE2- dependent natriuresis, EP-selective prostanoids were infused. The EP2agonist butaprost produced natriuresis (from 0.06 ± 0.02 to 0.32 ± 0.05 μeq/min). The natriuretic effect of intramedullary PGE2or butaprost was abolished in EP2-deficient mice, which exhibit NaCl-dependent hypertension. In conclusion, a high-salt diet increases renal medullary COX2 and mPGES1 expression, and increases renal medullary PGE2synthesis. Renal medullary PGE2promotes renal sodium excretion via the EP2 receptor, thereby maintaining normotension in the setting of high salt intake.

The eukaryotic endomembrane system can be defined as all the organelles comprising both the endocytic and secretory pathways, including the endoplasmic reticulum (ER), Golgi apparatus, endosomes, multivesicular bodies, lysosomes, vacuoles, plasma membrane, and transport intermediates such as vesicles and microvesicles. These membrane-enclosed compartments form a complex intracellular system that can comprise a large percentage of the total cellular volume. To understand the interrelationships between these intracellular compartments it is helpful to consider how each might have evolved. One of the most significant advances in evolution from prokaryotes to eukaryotes was the development of extensive cellular compartmentalization (Stanier 1970), facilitated by the proliferation of internal membranes (Blobel 1980). This elaboration of internal membranes allowed for an organelle-based division of labor for the biochemistry that was previously restricted to the surface of prokaryotic cells (Becker and Melkonian 1996).

The aim of this study was to purify and analyse a Phanerochaete chrysosporium cbh I.1 gene-product expressed as an inducible, secreted, heterologous protein from an Escerichia coli pGEX cbh I.1 clone. Using glutathione Sepharose 4B affinity chromatography, the expressed protein was purified from the supernatant of an induced E. coli transformed with pGEX cbh I.1 and ran as a single band on a Sodium dodecyl sulphate-polyacrylamide gel. The glutathione S-transferase (GST) fused CBHI.1 was approx-imately 80 kDa in size, approximately 2.2 kDa smaller than the theoretically predicted size. The purified protein exhibited time dependent hydrolytic reaction against carboxy-methyl-cellulose (CMC) and Avicel. On CMC the highest hydrolytic reaction occurred at 120 min. whereas for Avicel it was at 150 min. Optimum pH and temperature for activity of the protein against these cellulose substrates were pH 6 and 55oC, respectively, and the protein remained stable under these optimum conditions for 24 h. Key Words: Phanerochaete chrysosporium , cellobiohydrolase purification, heterologus expression. African Journal of Biotechnology Vol.3(7) 2004: 349-352

The nature of the stimulus sensed by bone cells during mechanical usage has not yet been determined. Because nitric oxide (NO) and prostaglandin (PG) production appear to be essential early responses to mechanical stimulation in vivo, we used their production to compare the responsiveness of bone cells to strain and fluid flow in vitro. Cells were incubated on polystyrene film and subjected to unidirectional linear strains in the range 500–5,000 microstrain (με). We found no increase in NO or PGE2production after loading of rat calvarial or long bone cells, MC3T3-E1, UMR-106–01, or ROS 17/2.8 cells. In contrast, exposure of osteoblastic cells to increased fluid flow induced both PGE2and NO production. Production was rapidly induced by wall-shear stresses of 148 dyn/cm2and was observed in all the osteoblastic populations used but not in rat skin fibroblasts. Fluid flow appeared to act through an increase in wall-shear stress. These data suggest that mechanical loading of bone is sensed by osteoblastic cells through fluid flow-mediated wall-shear stress rather than by mechanical strain.

The presence of chloride-formate anion exchange in vascular smooth muscle cells (VSMCs) and cardiac myocytes was investigated. Imposing an outward chloride gradient in sarcolemmal microsomes isolated from canine aorta stimulated [14C]formate uptake compared with the absence of a chloride gradient (24.3 +/- 2.33 versus 9.8 +/- 1.41 pmol/mg protein for 30 seconds, P < .03) and induced transient uphill [14C]formate uptake. The chloride-formate exchange was significantly inhibited in the presence of 1 mmol/L 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS) or furosemide (57% and 61%, respectively). Incubation of rat cultured VSMCs in a medium containing [14C]formate resulted in uptake of formate that was significantly DIDS and furosemide sensitive (79.34 +/- 2.47, 43.03 +/- 2.37, and 44.65 +/- 1.68 pmol/mg protein for 4 minutes in control, DIDS, and furosemide groups, respectively). Preincubation of the VSMCs in chloride-free medium significantly reduced the DIDS-sensitive (36.31 versus 16.85 pmol/mg protein for 4 minutes, P < .001) and furosemide-sensitive (34.72 versus 8.78 pmol/mg protein for 4 minutes, P < .001) [14C]formate uptake. These results are compatible with the presence of chloride-formate exchange in VSMCs. Influx of [14C]formate into sarcolemmal vesicles isolated from canine heart was significantly higher in the presence of an outward chloride gradient than in its absence (18.1 +/- 2.3 versus 9.6 +/- 1.7 pmol/mg protein for 30 seconds, P < .03). The chloride-formate exchange was significantly inhibited in the presence of 1 mmol/L DIDS or furosemide (41% and 52%, respectively). We conclude that the distribution of chloride-formate exchange may be more universal than previously suggested.(ABSTRACT TRUNCATED AT 250 WORDS)

Late blight is caused by the oomycete Phytophthora infestans (Mont.) de Bary and is one of the most devastating diseases of potato and tomato. Late blight occurs in all major potato- and tomato-growing regions of Canada. Its incidence in North America increased during 2009 and 2010 (2). Foliar disease symptoms appeared earlier than usual (June rather than July) and coincided with the identification of several new P. infestans genotypes in the United States, each with unique characteristics. Prior to 2007, isolates collected from potato and tomato crops were mainly US8 or US11 genotypes (1). However, P. infestans populations in the United States have recently experienced a major genetic evolution, producing isolates with unique genotypes and epidemiological characteristics in Florida and throughout the northeastern states (2). Recent discoveries of tomato transplants with late blight for sale at Canadian retail outlets prompted an examination of the genotypes inadvertently being distributed and causing disease in commercial production areas in Canada. Analysis of isolates of P. infestans from across Canada in 2010 identified the US23 genotype for the first time from each of the four western provinces (Manitoba, Saskatchewan, Alberta, and British Columbia) but not from eastern Canada. Allozyme banding patterns at the glucose phosphate isomerase (Gpi) locus indicated a 100/100 profile consistent with US6 and US23 genotypes (4). Mating type assays confirmed the isolates to be A1 and in vivo metalaxyl sensitivity was observed. Restriction fragment length polymorphic analysis of 50 isolates from western Canada with the multilocus RG57 sequence and EcoRI produced the DNA pattern 1, 2, 5, 6, 10, 13, 14, 17, 20, 21, 24, 24a, 25 that was indicative of US23 (3). The recently described P. infestans genotype US23 appears to be more aggressive on tomato, and although isolates were recovered from both tomato and potato, disease symptoms were often more severe on tomato. Results indicate that movement and evolution of new P. infestans genotypes have contributed to the increased incidence of late blight and that movement of the pathogen on retail plantlets nationally and internationally may provide an additional early season source of inoculum. A major concern is that the introduced new A1 populations in western Canada have established a dichotomy with the endogenous A2 populations in eastern Canada, increasing the potential for sexual recombination producing oospores and additional genotypes should these populations merge. References: (1) Q. Chen et al. Am. J. Potato Res. 80:9, 2003. (2) K. Deahl. (Abstr.) Phytopathology 100(suppl.):S161, 2010. (3) S. B. Goodwin et al. Curr. Genet. 22:107, 1992. (4) S. B. Goodwin et al. Phytopathology 88:939, 2004.

Sodium and water retention is characteristic of edematous disorders including cardiac failure, cirrhosis, nephrotic syndrome, and pregnancy. Nonosmotic vasopressin release has been implicated in the water retention of these edematous disorders. The nonosmotic release of vasopressin is consistently associated with activation of the sympathetic nervous and renin-angiotensin-aldosterone systems in both experimental animals and in edematous patients. Moreover, the sympathetic nervous system has been shown to be involved in the nonosmotic release of vasopressin and activation of the renin-angiotensin system. These findings have led to our proposal that body fluid volume regulation involves the dynamic interaction between cardiac output and peripheral arterial resistance. Neither total extracellular fluid volume nor blood volume is a determinant of renal sodium and water excretion. Rather, renal sodium and water retention is initiated by a decrease in effective arterial blood volume (EABV) due to either a fall in cardiac output or peripheral arterial vasodilation. The acute response to a decrease in EABV involves vasoconstriction mediated by angiotensin, sympathetic mediators, and vasopressin. The slower response to restoring EABV involves vasopressin-mediated water retention and aldosterone-mediated sodium retention. The resultant renal vasoconstriction limits the distal tubular delivery of sodium and water, thus maximizing the water-retaining effect of vasopressin and impairing the normal escape from the sodium-retaining effects of aldosterone. The elevated glomerular filtration rate and filtered sodium load in pregnancy allows increased distal sodium and water delivery in spite of a decrease in EABV, thus limiting edema formation during gestation.

The phospholipid and fatty acid compositions of the host infected erythrocyte plasma membrane (IEPM) have been determined for erythrocytes infected with the human malaria parasite Plasmodium falciparum. IEPM were prepared by selective lysis of the host erythrocyte (but not of the parasite membranes) with 0.1% saponin, followed by differential centrifugation. The purity of the IEPM was determined by measuring the membrane-specific enzyme markers acetylcholinesterase, glutamate dehydrogenase and lactate dehydrogenase, and by immunoelectron microscopy using monoclonal antibodies specific for human erythrocyte glycophorin A (4E7) and for a 195 kDa parasite membrane glycoprotein (Pf6 3B10.1). Both approaches demonstrated that the host erythrocyte plasma membrane preparation was free from contamination by parasite membranes. During intra-erythrocytic development of the parasite, the phospholipid composition of the erythrocyte membrane was strikingly altered. IEPM contained more phosphatidylcholine (38.7% versus 31.7%) and phosphatidylinositol (2.1% versus 0.8%) and less sphingomyelin (14.6% versus 28.0%) than normal uninfected erythrocytes. Similar alterations in phospholipid composition were determined for erythrocyte membranes of parasitized cells isolated by an alternative method utilizing polycationic polyacrylamide microbeads (Affigel 731). The total fatty acid compositions of the major phospholipids in IEPM were determined by g.l.c. The percentage of polyunsaturated fatty acids in normal erythrocyte phospholipids (39.4%) was much higher than in phospholipids from purified parasites (23.3%) or IEPM (24.0%). The unsaturation index of phospholipids in IEPM was considerably lower than in uninfected erythrocytes (107.5 versus 161.0) and was very similar to that in purified parasites (107.5 versus 98.5). Large increases in palmitic acid (C16:0) (from 21.88% to 31.21%) and in oleic acid (C18:1) (from 14.64% to 24.60%), and major decreases in arachidonic acid (C20:4) (from 17.36% to 7.85%) and in docosahexaenoic acid (C22:6) (from 4.34% to 1.8%) occurred as a result of infection. The fatty acid profiles of individual phospholipid classes from IEPM resembled in many instances the fatty acid profiles of parasite phospholipids rather than those of uninfected erythrocytes. Analysis of IEPM from P. falciparum-infected erythrocytes (trophozoite stage) revealed that, during intra-erythrocytic maturation of the parasite, the host erythrocyte phospholipid composition was markedly refashioned. These alterations were not dependent on the method used to isolate the IEPM, with similar results obtained using either a saponin-lysis method or binding to Affigel beads. Since mature erythrocytes have negligible lipid synthesis and metabolism, these alterations must occur as a result of parasite-directed metabolism of erythrocyte lipids and/or trafficking of lipids between the parasite and erythrocyte membranes.

A 36-year-old dental technician for 14 years developed paraesthesia and numbness in her legs. Neurophysiological studies revealed absent sensory nerve action potentials (SNAPs) from her lower limbs and normal upper limb SNAPs on presentation. Motor nerve studies were normal. Repeat studies 2 months after leaving her job showed some improvement in the lower limb SNAPs. It is suggested that her symptoms were caused by occupational exposure to methyl methacrylate monomer.

Leucostoma persoonii (anamorph = Cytospora leucostoma) is a pathogen that causes early dieback and canker disease on a variety of fruit trees in North America. It has recently been recognized as an economically important disease of saskatoon (Amelanchier spp.) in Alberta, Canada. Isolates from infected bushes from five locations in Alberta were studied to determine the extent of strain variability and to investigate mechanisms of pathogenesis. Differences among isolates were found to be significant with respect to cultural characteristics on various media, and growth responses of the isolates to a range of temperatures also varied significantly. Oxalic acid production was observed in cultures of C. leucostoma [...]

Recombinant and synthetic peptide technology has allowed new approaches to the study of parasitic diseases. A major benefit of these advances is the ease with which entire genes can be isolated and sequenced at the nucleotide level. This information can help answer questions on genomic organization and evolution. Moreover, we can deduce the entire amino acid sequence of a particular protein without having sufficient protein to visualize on an acrylamide gel. The challenge of translating the nucleotide sequence into a biologically relevant and functional protein remains. We intend to focus attention on a particular way to accomplish that translation, i.e., the use of polypeptides derived from the deduced sequence to probe or model a function or property of the protein. It is often easier to obtain large amounts of relatively pure recombinant or synthetic polypeptides than the original protein. Caveats about the use of such peptides cannot be overstated. Proteins are not simply linear entities but often have essential tertiary and quaternary elements that cannot be duplicated by short peptides. The region selected may be internal in the final protein or processed or modified at an early stage of synthesis. Despite these pitfalls, a substantial insight has been achieved in studies with recombinant and synthetic peptides. Ongoing work in seven laboratories concerned is summarized. Keywords: Antigens, Host-parasite relations, Mice, Plasmodium, Malaria, Reprints.

SUMMARY Beating, a pulp treatment widely used in the paper industry, causes disruption of cell wall layers and fibrillation. Previous studies of the effects of beating on fibre morphology have used conventional methods of specimen preparation, with all the attendant problems of shrinkage and distortion during dehydration. Low-temperature scanning electron microscopy (LTSEM) therefore seemed to offer an ideal method for examining fully hydrated wood pulp fibres. Cryofixation of pulp followed by sublimation of superficial ice, however, is shown to generate artefacts indistinguishable from structures present in the samples. Fibrillar and membranous structures were generated in LTSEM-prepared sugar solutions; their presence in pulp samples was therefore attributed to the dissolved carbohydrates inherent in pulp suspensions. Since artefact and fact are currently impossible to distinguish in LTSEM-prepared pulp samples, it seems that the technique should be applied to wet paper or pulp samples with considerable circumspection.

The effects of verapamil on the force of contraction of soleus and gastrocnemius muscles of the cat were examined in vivo. The rapid intra-arterial administration of verapamil (100-800 micrograms/kg) produced a dose-dependent increase in the contractile force of soleus and gastrocnemius muscles stimulated supramaximally via their nerves. Verapamil also potentiated twitch tension in d-tubocurarine-treated, directly stimulated soleus preparations. This agent had no effect, however, on the contractile force of 14- to 16-day chronically denervated, directly stimulated soleus muscle. Verapamil (400 microgram/kg, i.a.) also produced a significant increase in muscle action potential duration while having no effect on amplitudes, rise times or resting membrane potential. It is concluded that verapamil acts directly on innervated skeletal muscle to increase muscle force and it is suggested that the probable site of action is at the muscle membrane.

Conflicting recommendations exist on the effect of seed-applied pesticides on nodulation and N2 fixation by Rhizobium leguminosarum. This paper reports the effects of captan, thiram, metalaxyl, Evershield, DL-PLUS® and B-3 in a 2-yr field experiment on emergence, nodulation, acetylene-reducing activity, and shoot yield of pea (Pisum sativum L.), lentil (Lens culinaris L.), and fababean (Vicia faba L.) inoculated with seed-applied R. leguminosarum multi-strain inoculum. Seedling emergence was not detrimentally affected by pesticide application. While most of the pesticides had either stimulatory or minimally detrimental effects on nodulation and nitrogenase activity, captan reduced both in all three legumes. Captan-containing compounds such as B-3 (33.5% captan) and Evershield (29.5% captan) also reduced nodulation or nitrogenase activity in some of these legumes. DL-PLUS (15% captan) was not harmful, which suggests that compounds containing over 29.5% captan may not be compatible with seed-applied R. leguminosarum. Captan, which was consistently harmful, is considered the best wide-spectrum pesticide for use with these legumes. Thus, it will be necessary to select superior N2-fixing strains of R. leguminosarum that are tolerant of, if not resistant to, recommended rates of captan or to identify alternate pesticides that are more compatible with rhizobia.Key words: Captan, thiram, metalaxyl, Evershield, DL-PLUS, B-3

The stability constants and forward and reverse rate constants have been determined for adduct formation reactions involving tetra-μ-acetato, tetra-μ-propionate and tetrakis-μ-methoxyacetatodirhodium(II) with the ligands pyridine, picolinic acid, niacin and isonicotinic acid. The experimentally observed stability trend is isonicotinic acid > pyridine ⋍ niacin ⪢ picolinic acid. It appears that the π bonding ability of the ligands determines the order of stability of these adducts. The variation of the stabilities of the adducts formed from different tetra-μ-carbox-ybtodlrhodium(II) complexes and a given ligand is related to an inductive effect as well as the lipophylic nature of the carboxylate side chain. The more hydropholic character of the propionate species apparently exerts a desolvating effect at the two axial positions resulting in a more rapid ligand exchange.

The redox reactions of a series of tetra-μ-carboxylatodirhodium(II) complexes, Rh2(O2CR)4, were investigated in both aqueous and non-aqueous media at platinum and mercury electrodes. Ten different complexes of Rh2(O2CR)4 were chosen in which R varied from an electron donating to an electron withdrawing substituent. For each compound, a diffusion controlled one electron oxidation and an irreversible multielectron reduction was obtained. The potentials of each reaction were related linearly to the Gutmann donor number and to the substituent, R. The antitumor activity of Rh2(O2CC2H5)4 and of the oxidized complex [Rh2(O2CC2H5)]+ was also compared, showing the oxidized species was slightly more active than the neutral complex. No definite trend between redox and antitumor activity of Rh2(O2CR)4 complexes was observed.

Textured surfaces consisting of submicron columns or cones have been formed in a variety of surfaces using reactive ion etching. On metals, insulators, and semiconductors this texturing forms a graded index matching layer which reduces reflection of visible light to as low as 0.1%. The optical properties can be permanently altered on a ∠l μm size scale by irradiation with a low power laser beam and this has been explored as a new optical storage medium. The light energy transforms the optically absorbing textured surface to a nonabsorbing smooth one by melting. Reflectance changes of greater than a factor of 100 have been demonstrated at ∠10 mW light power. The textured surfaces have also been used with dielectric materials to create high transparency optical elements. Highly absorbing films of Ge and Si, that were earlier studied as solar photothermal absorbers, have been investigated as optical storage media. The production, morphology and optical properties of these surfaces are described.

Direct writing of micron‐sized features in self‐developing photoresists is demonstrated using less than 1 mW of cw ultraviolet light at 257 nm. No energy density or intensity thresholds for ablation are observed. Ablation depth depends only on the deposited energy density and is independent of the rate of deposition; that is, the self‐developing process is reciprocal. We have determined that an environment containing oxygen is necessary for complete self‐developing; in the absence of O2 the process is self‐limiting. Patterns created in poly(methyl methacrylate) have been faithfully reproduced into silicon substrates using reactive‐ion etching.

We describe a trilevel e‐beam resist process based on the high resolution resist PMMA. This process has been used to form metal features 25 nm wide on thick Si substrates by liftoff. Ni–Cr films patterned in this way have been used as masks for reactive ion etching of Si. The resulting structures were arrays of fins ∠ 30 nm wide and 330 nm high on 95 nm centers with a total length of 3 μm. We also discuss the resolution improvement obtained in a trilevel process based on a higher speed resist, P (MMA/MAA).

A modified toluidine blue O staining technique for Pneumocystis carinii is described. An easily prepared sulfation reagent made with sulfuric and acetic acids was used. The stain can be employed for bronchoalveolar lavages and lung tissue touch preparations. Most background material was removed by the sulfation reagent, slides were generally easy to read, and time from receipt of a specimen to reporting of results was approximately 1 h. P. carinii cysts were more easily visualized with this stain than in slides stained with modified methylene blue, Gram, Gram-Weigert, and standard toluidine blue O procedures. The importance of certain procedural aspects of subsegmental bronchoalveolar lavage, by which most of the specimens were obtained, is also emphasized.