Expression of seven members of the gene family encoding secretory aspartyl proteinases in Candida albicans

The opportunistic fungal pathogen Candida albicans produces secretory aspartyl proteinases, which are believed to be virulence factors in infection. We have studied the in vitro expression of seven known members of the SAP gene family in a range of strains and serotypes by Northern analysis. SAP1 and SAP3 were regulated during phenotypic switching between the white and opaque forms of the organism. The SAP2 mRNA, which was the dominant transcript in the yeast form, was found to be autoinduced by peptide products of Sap2 activity and to be repressed by amino acids. The expression of the closely related SAP4-SAP6 genes was observed only at neutral pH during serum-induced yeast to hyphal transition. No SAP7 mRNA was detected under any of the conditions or in any of the strains tested. Our data suggest that the various members of the SAP gene family may have distinct roles in the colonization and invasion of the host.

Spectrum of hSNF5/INI1 somatic mutations in human cancer and genotype-phenotype correlations

The hSNF5/INI1 gene which encodes a member of the SWI/SNF chromatin ATP-dependent remodeling complex, is a new tumor suppressor gene localized on chromosome 22q11.2 and recently shown to be mutated in malignant rhabdoid tumors. We have searched for hSNF5/INI1 mutations in 229 tumors of various origins using a screening method based on denaturing high-performance liquid chromatography. A total of 31 homozygous deletions and 36 point alterations were identified. Point mutations were scattered along the coding sequence and included 15 nonsense, 15 frameshift, three splice site, two missense and one editing mutations. Mutations were retrieved in most rhabdoid tumors, whatever their sites of occurrence, indicating the common pathogenetic origin of these tumors. Recurrent hSNF5/INI1 alterations were also observed in choroid plexus carcinomas and in a subset of central primitive neuroectodermal tumors (cPNETs) and medulloblastomas. In contrast, hSNF5/INI1 point mutations were not detected in breast cancers, Wilms' tumors, gliomas, ependymomas, sarcomas and other tumor types, even though most analyzed cases harbored loss of heterozygosity at 22q11.2 loci. These results suggest that rhabdoid tumors, choroid plexus carcinomas and a subset of medulloblastomas and cPNETs share common pathways of oncogenesis related to hSNF5/INI1 alteration and that hSNF5/INI1 mutations define a genetically homogeneous family of highly aggressive cancers mainly occurring in young children and frequently, but not always, exhibiting a rhabdoid phenotype.

Use of genetically engineered phage to deliver antimicrobial agents to bacteria: an alternative therapy for treatment of bacterial infections

The emergence and increasing prevalence of multidrug-resistant bacterial pathogens emphasizes the need for new and innovative antimicrobial strategies. Lytic phages, which kill their host following amplification and release of progeny phage into the environment, may offer an alternative strategy for combating bacterial infections. In this study, however, we describe the use of a nonlytic phage to specifically target and deliver DNA encoding bactericidal proteins to bacteria. To test the concept of using phage as a lethal-agent delivery vehicle, we used the M13 phagemid system and the addiction toxins Gef and ChpBK. Phage delivery of lethal-agent phagemids reduced target bacterial numbers by several orders of magnitude in vitro and in a bacteremic mouse model of infection. Given the powerful genetic engineering tools available and the present knowledge in phage biology, this technology may have potential use in antimicrobial therapies and DNA vaccine development.

Candida albicans-conditioned medium protects yeast cells from oxidative stress: a possible link between quorum sensing and oxidative stress resistance

Candida albicans, the most frequent fungal pathogen of humans, encounters high levels of oxidants following ingestion by professional phagocytes and through contact with hydrogen peroxide-producing bacteria. In this study, we provide evidence that C. albicans is able to coordinately regulate the oxidative stress response at the global cell population level by releasing protective molecules into the surrounding medium. We demonstrate that conditioned medium, which is defined as a filter-sterilized supernatant from a C. albicans stationary-phase culture, is able to protect yeast cells from both hydrogen peroxide and superoxide anion-generating agents. Exponential-phase yeast cells preexposed to conditioned medium were able to survive levels of oxidative stress that would normally kill actively growing yeast cells. Heat treatment, digestion with proteinase K, pH adjustment, or the addition of the oxidant scavenger alpha-tocopherol did not alter the ability of conditioned medium to induce a protective response. Farnesol, a heat-stable quorum-sensing molecule (QSM) that is insensitive to proteolytic enzymes and is unaffected by pH extremes, is partly responsible for this protective response. In contrast, the QSM tyrosol did not alter the sensitivity of C. albicans cells to oxidants. Relative reverse transcription-PCR analysis indicates that Candida-conditioned growth medium induces the expression of CAT1, SOD1, SOD2, and SOD4, suggesting that protection may be mediated through the transcriptional regulation of antioxidant-encoding genes. Together, these data suggest a link between the quorum-sensing molecule farnesol and the oxidative stress response in C. albicans.

Phage-based platforms for the clinical detection of human bacterial pathogens

Bacteriophages (phages) have been utilized for decades as a means for uniquely identifying their target bacteria. Due to their inherent natural specificity, ease of use, and straightforward production, phage possess a number of desirable attributes which makes them particularly suited as bacterial detectors. As a result, extensive research has been conducted into the development of phage, or phage-derived products to expedite the detection of human pathogens. However, very few phage-based diagnostics have transitioned from the research lab into a clinical diagnostic tool. Herein we review the phage-based platforms that are currently used for the detection of Mycobacterium tuberculosis, Yersinia pestis, Bacillus anthracis and Staphylococcus aureus in the clinical field. We briefly describe the disease, the current diagnostic options, and the role phage diagnostics play in identifying the cause of infection, and determining antibiotic susceptibility.

Regulation of chitin synthesis during dimorphic growth of Candida albicans

Candida albicans has three genes encoding chitin synthase enzymes. In wild-type strains, the expression of CHS2 and CHS3 peaked 1-2 h after the induction of hyphal growth, whilst mRNA levels in a non-germinative strain, CA2, remained low under the same conditions. CHS1 gene expression did not peak during germ tube formation but remained at low levels in both yeast and hyphal growth. The pattern of gene expression did not predict the changes in measured chitin synthase activities or changes in chitin content during dimorphic transition. Chitin synthase activity increased steadily, and did not peak shortly after germ tube induction, and activity profiles were similar in germ-tube-competent and germ-tube-negative strains. The phenotype of a delta chs2 null mutant suggested that CHS2 encoded the major enzyme activity in vitro and was largely responsible for elevated chitin synthase activities in microsomal preparations from hyphal cells compared to yeast cells. However, CaChs3p was responsible for synthesis of most chitin in both yeast and hyphae. Three independent chitin assays gave markedly different estimates of the relative chitin content of yeast and hyphae and wild-type and chs mutants. Only one of the methods gave a significantly higher chitin content for hyphal compared to yeast cell walls and a lower chitin content for hyphae of the delta chs2 null mutant compared to the parental strain.

Antioxidant therapy for recurrent pancreatitis: biochemical profiles in a placebo-controlled trial

The usefulness of micronutrient antioxidant therapy for recurrent (non-gallstone) pancreatitis has recently been endorsed by a 20-week double-blind double-dummy cross-over trial in 20 patients. Treatment was delivered as two types of tablets, providing daily doses of 600 micrograms organic selenium, 9000 i.u. beta-carotene, 0.54 g vitamin C, 270 i.u. vitamin E and 2 g methionine. We report antioxidant profiles in blood samples collected before entry, at the cross-over stage and upon completion of trial. Baseline serum concentrations of selenium, beta-carotene and vitamin E in the patients were significantly lower than in healthy controls, were unaltered by placebo and normalized by active treatment, but reverted to basal values in the subgroup that received placebo subsequently. The baseline serum concentration of a free radical marker--the 9-cis, 11-trans isomer of linoleic acid--was significantly higher in the patients than in controls, fell inexplicably in the placebo phase and fell further upon active treatment. Discriminant analysis eliminated the overlap in free radical marker and selenium concentrations between control sera on the one hand and baseline or post-placebo samples from the patients on the other: antioxidant treatment normalized the relationship between these biochemical parameters. Subnormal baseline serum levels of S-adenosylmethionine drifted downwards upon active treatment whereas a sharp rise was noted when a relapse of pancreatitis occurred during the placebo phase. The results confirm that adequate exposure to antioxidants in the active treatment phase was associated with amelioration of oxidative stress, and that there was no residual effect 10 weeks after switching over to placebo treatment. Furthermore, the paradoxical behaviour of S-adenosylmethionine may imply that the beneficial effect of micronutrient antioxidants in recurrent pancreatitis is linked with preservation of the methionine trans-sulfuration pathway in pancreatic acinar cells.

Reasons for cannabis use in psychosis

OBJECTIVE

To examine the reasons for cannabis use among individuals with psychotic disorders.

METHOD

Forty-nine people with psychotic disorders in treatment with community health centres in Northern Sydney were interviewed to collect information about their experience of antipsychotic side-effects and their influence on cannabis use. Other information collected on cannabis use included: amount and frequency, effects of use and other general reasons given for use.

RESULTS

It was found that boredom, social motives, improving sleep, anxiety and agitation and symptoms associated with negative psychotic symptoms or depression were the most important motivators of cannabis use. Positive symptoms of psychosis and antipsychotic side-effects that were not associated with anxiety, were not important motivators of cannabis use.

CONCLUSIONS

As cannabis use may precipitate relapse in this population, it is important to reduce these motivators of use. Clinician's must assess and treat these problems, thus reducing the need for patients to self-medicate with cannabis, and therefore reducing the risk of relapse.

Low dose computed tomography in suspected acute renal colic

AIM

To evaluate whether computed tomography (CT) of the renal tract in suspected renal colic using reduced exposure factors maintains diagnostic accuracy.

METHODS

Prospective multi-centre cohort study. Patients with suspected renal colic were examined using computed tomography (CT) of the renal tract followed by intravenous urography (IVU) in four different centres with five different CT systems.

RESULTS

Sixty-nine patients with suspected renal colic had CT of the renal tract followed by IVU. CT was performed with reduced exposure factors, giving a mean CT effective dose of 3.5 (range 2.8-4.5) mSv compared with 1.5 mSv for IVU. Ureteric calculi were detected in 43 patients: CT and IVU detected 40 (93%) ureteric calculi. CT identified other lesions causing symptoms in five patients and identified renal calculi in 24 patients. IVU identified renal calculi in six patients and made false positive diagnosis of renal calculi in seven patients. Mean examination time for CT was 5 minutes and for IVU was 80 minutes.

CONCLUSION

CT examination at reduced exposure factors maintains the diagnostic accuracy recorded in other series.

The temporal dynamics of relationships between cannabis, psychosis and depression among young adults with psychotic disorders: findings from a 10-month prospective study

BACKGROUND

The aim was to examine the temporal relationships over 10 months between cannabis use and symptoms of psychosis and depression in people with schizophrenia and related disorders. The design was a prospective study of 101 patients with schizophrenia and related disorders who were assessed monthly over 10 months on medication compliance, cannabis and other drug use, symptoms of depression and symptoms of psychosis.

METHOD

Linear regression methods to assess relationships between cannabis use and symptoms of psychosis and depression while adjusting for serial dependence, medication compliance and other demographic and clinical variables.

RESULTS

Cannabis use predicted a small but statistically significant increase in symptoms of psychosis, but not depression, after controlling for other differences between cannabis users and non-users. Symptoms of depression and psychosis did not predict cannabis use.

CONCLUSION

Continued cannabis use by persons with schizophrenia predicts a small increase in psychotic symptom severity but not vice versa.

Micronutrient antioxidant status in tropical compared with temperate-zone chronic pancreatitis

Micronutrient antioxidants interact with glutathione in tissues to facilitate the disposal of reactive oxygen species and xenobiotic metabolites derived via cytochromes P450. Published evidence linking cytochrome P450I induction with chronic pancreatitis therefore led us to compare antioxidant status in patients at Manchester in the northwest of England and at Madras in the southeast of India. Serum studies in healthy volunteers showed that the biologic availabilities of selenium and alpha-tocopherol were equally high in the two zones but that the availabilities of beta-carotene and ascorbic acid were lower in the tropical area (p < 0.001), where the ratio of ascorbic acid to total vitamin C concentration in serum was substantially reduced (p < 0.001). The serum antioxidant profiles of the chronic pancreatitis groups reflected these indigenous differences: a decrement in selenium and alpha-tocopherol was evident in both zones, whereas beta-carotene and ascorbic acid values were subnormal only in the Manchester group. The concentration of inorganic sulphate in urine--an index of long-term intake of sulphur amino acids for synthesis of glutathione and other detoxifiers--was similar in controls and patients from Manchester, but levels were lower than in their Madras counterparts (p < 0.02, p < 0.01, respectively). The results suggest that culinary practices that erode the biologic availabilities of ascorbic acid and beta-carotene may predispose to pancreatic oxidative stress and thereby to the changes leading to chronic pancreatitis at an early age in south India. These findings have implications for treatment and prophylaxis.

Vitamin C status in patients with acute pancreatitis

Vitamin C is a key antioxidant in human blood plasma and hence could influence the outcome of conditions such as acute pancreatitis in which oxidative stress apparently plays a pivotal role. The concentrations of vitamin C and its immediately bioavailable form, ascorbic acid, in fasting plasma samples from 30 healthy volunteers were compared with those in admission samples from 29 consecutive patients with acute pancreatitis and 27 patients with other acute abdominal crises. Median (range) levels of vitamin C and ascorbic acid, respectively, were 15 (6.3-19) and 12 (4.5-18) micrograms/ml in the control group, 2.8 (0.3-10) and < 0.5 (< 0.5-6.0) micrograms/ml in patients with acute pancreatitis, and 3.7 (0.6-15) and 2.3 (< 0.5-15) micrograms/ml in those with other acute abdominal problems. Admission plasma samples showed equally low vitamin C levels in both groups of patients (P < 0.001 versus controls), but those from patients with acute pancreatitis were further characterized by a disproportionate reduction in ascorbic acid, such that the concentration of ascorbic acid and its ratio to vitamin C were both significantly lower than in samples from patients with an acute abdomen (P < 0.005 and P < 0.001 respectively). It is concluded that the stress of an acute intra-abdominal crisis is accompanied by a non-specific decrease in the plasma level of vitamin C. In acute pancreatitis early and profound oxidative stress compounds this problem by denaturing the available vitamin. There may be a case for the judicious parenteral administration of ascorbic acid to patients with acute pancreatitis to boost plasma antioxidant defence.

Highly selective kappa opioid analgesics. Synthesis and structure-activity relationships of novel N-[(2-aminocyclohexyl)aryl]acetamide and N-[(2-aminocyclohexyl)aryloxy]acetamide derivatives

This paper describes the synthesis, structure-activity relationships (SAR) of mu and kappa opioid binding affinities, and analgesic properties of a series of novel highly selective kappa opioid N-[(2-aminocyclohexyl)aryl]acetamide and N-[(2-aminocyclohexyl)aryloxy] acetamide derivatives. Ten compounds, 14, 15, 31-37, and 39 (Tables I and II), show a marked kappa selectivity of greater than 100:1 over mu binding, with high affinity for the kappa opioid receptor (approximately 10(-8) - 10(-9) M). Compound 39, (S,S-trans)-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]-4-benzo[b] furanacetamide hydrobromide, has the highest mu/kappa selectivity, 780:1 (kappa Ki = 4.2 nM), reported to date. Four of these compounds, 14, 15, and their S,S-trans enantiomers, 37 and 39, respectively, produce effective analgesia by oral administration, as assayed by a rat-paw pressure test (RPP) (MPE50 = 24, 26, 8.3, and 12 mg/kg, respectively). The R,R-trans isomer, 38, was inactive in binding and RPP. The analgesic effect was reversed by administration of naloxone, confirming these effects are opioid in character. Optimal activity is produced when the basic nitrogen atom is in a pyrrolidine ring, the aryl group is a 10-pi-electron-rich aromatic system, such as 4-benzo[b]thiophene, 4-benzo[b]furan, or 4-chlorophenoxy, and overall lipophilicity lies within the range log P = 3.5-5.0.

Generation of a mutagenized organophosphorus hydrolase for the biodegradation of the organophosphate pesticides malathion and demeton-S

AIMS

The bacterial organophosphorus hydrolase (OPH) enzyme hydrolyses and detoxifies a broad range of toxic organophosphate pesticides and warfare nerve agents by cleaving the various phosphorus-ester bonds (P-O, P-F, P-CN, P-S); however, OPH hydrolyses these bonds with varying efficiencies. The aim of this study was to generate a variant OPH enzyme with improved hydrolytic efficiency against the poorly hydrolysed P-S class of organophosphates.

METHODS AND RESULTS

The gene encoding OPH was sequentially mutated at specific codons by saturation mutagenesis and screened for improved activity against the P-S substrates demeton-S methyl and malathion. Escherichia coli lysates harbouring the variants displayed up to 177- and 1800-fold improvement in specific activity against demeton-S methyl and malathion, respectively, compared to the wild-type lysates. The specificity constants of the purified variant proteins were improved up to 25-fold for demeton-S methyl and malathion compared to the wild-type. Activity was associated with organophosphate detoxification as the hydrolysed substrate lost the ability to inhibit acetylcholinesterase. The improved hydrolytic efficiency against demeton-S translated to the improved ability to hydrolyse the warfare agent VX.

CONCLUSIONS

OPH variant enzymes were generated that displayed significantly improved ability to hydrolyse and detoxify organophosphates harbouring the P-S bond.

SIGNIFICANCE AND IMPACT OF THE STUDY

The long-term goal is to generate an environmentally-friendly enzyme-mediated bioremediation approach for the removal of toxic organophosphate compounds in the environment.

Differential Candida albicans lipase gene expression during alimentary tract colonization and infection

The human pathogenic fungus Candida albicans, which can reside as a benign commensal of the gut, possesses a large family of lipase encoding genes whose extracellular activity may be important for colonization and subsequent infection. The expression of the C. albicans lipase gene family (LIP1-10) was investigated using a mouse model of mucosal candidiasis during alimentary tract colonization (cecum contents) and orogastric infection. LIPs4-8 were expressed in nearly every sample prepared from the cecum contents and infected mucosal tissues (stomach, hard palate, esophagus and tongue) suggesting a maintenance function for these gene products. In contrast, LIPs1, 3, and 9, which were detected consistently in infected gastric tissues, were essentially undetectable in infected oral tissues. In addition, LIP2 was expressed consistently in cecum contents but was undetectable in infected oral tissues suggesting LIP2 may be important for alimentary tract colonization, but not oral infection. The host responded to a C. albicans infection by significantly increasing expression of the chemokines MIP-2 and KC at the site of infection. Therefore, differential LIP gene expression was observed during colonization, infection and at different infected mucosal sites.

Intravenous n-acetylcysteine, ascorbic acid and selenium-based anti-oxidant therapy in severe acute pancreatitis

BACKGROUND

To observe outcome in a cohort of patients with severe acute pancreatitis receiving multiple anti-oxidant therapy.

METHODS

An observational study was carried out in 46 consecutive patients with acute pancreatitis fulfilling current Atlanta consensus criteria for severe disease. All patients received multiple anti-oxidant therapy based on intravenous selenium, N-acetylcysteine and ascorbic acid plus beta-carotene and alpha-tocopherol delivered via nasogastric tube. Principal outcomes were the effect of anti-oxidant supplementation on anti-oxidant levels, morbidity and mortality in patients on anti-oxidant therapy, case-control analysis of observed survival compared to predicted survival derived from logistic organ dysfunction score (LODS), logistic regression analysis of factors influencing outcome and side effect profile of anti-oxidant therapy.

RESULTS

Paired baseline and post-supplementation data were available for 25 patients and revealed that anti-oxidant supplementation restored vitamin C (P = 0.003) and selenium (P = 0.028) toward normal. In univariate survival analysis, patient survival to discharge was best predicted by admission APACHE-II score with relative risk of death increasing 12.6% for each unit increase (95% CI 6.0% to 19.6%). The mean LODS calculated on admission to hospital was 3.7 (standard error of the mean 4.1) giving a predicted mortality for the cohort of 21%. The observed in-hospital mortality was 43%.

CONCLUSIONS

Case-control analyses do not appear to demonstrate any benefit from the multiple anti-oxidant combination of selenium, N-acetylcysteine and ascorbic acid in severe acute pancreatitis.

Evidence for early oxidative stress in acute pancreatitis. Clues for correction

Pancreatic oxidative stress with depletion of pancreatic glutathione is an early feature in all tested models of acute pancreatitis, and sooner or later the problem extends to the lung, irrespective of disease severity, whether toward spontaneous recovery or death from multisystem organ failure. We, therefore, sought evidence of oxidative stress in the human disease by analyzing admission blood samples. We found it from high concentrations of oxidatively altered linoleic acid in serum and vitamin C in plasma (p < 0.001 vs controls or a group of other acute abdominal crises where the proportion of patients with admission Apache II scores < or > 8 was similar). These changes were accompanied by subnormal levels of ascorbic acid in plasma (p < 0.001); selenium (p < 0.001), beta-carotene (p < 0.001), and alpha-tocopherol in serum (p = 0.005 for its molar ratio to cholesterol). Paradoxically, the plasma concentration of S-adenosylmethionine was elevated (p = 0.02), suggesting that this proximate bioactive metabolite of the essential amino acid had backtracked because its intracellular metabolism down the methionine trans-sulfuration pathway toward glutathione synthesis was disrupted. The aberrations transcended putative etiological factor, duration of symptoms, or disease severity. We conclude: (1) that oxidative stress has pervaded the vascular compartment by the time of admission in patients with acute pancreatitis, and, (2) that blood micronutrient antioxidant profiles at this stage are consistent not only with compromised intracellular capacity to synthesize/refurbish glutathione, but also vulnerability of intra- and extracellular lipid targets.

Susceptibility of germfree phagocyte oxidase- and nitric oxide synthase 2-deficient mice, defective in the production of reactive metabolites of both oxygen and nitrogen, to mucosal and systemic candidiasis of endogenous origin

Mice deficient for phagocyte oxidase (Phox) and nitric oxide synthase 2 (NOS2) (gp91phox-/-/NOS2-/-), defective in the production of both reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI), were used to investigate the role of phagocytic cells during mucosal and systemic candidiasis of endogenous origin. The alimentary tracts of germfree mice were colonized with Candida albicans wild type or each of two hyphal signaling-defective mutants (efg1/efg1 and efg1/efg1 cph1/cph1). All Candida-colonized gp91phox-/-/NOS2-/- mice were moribund within 12 to 15 days after oral inoculation. C. albicans wild-type and mutant strains colonized the alimentary tracts equally well and were able to translocate, most likely via Peyer's patches and mesenteric lymph nodes, to the internal organs and trigger the formation of abscesses; however, the wild-type and mutant strains did not survive in the abscessed murine tissues. Surprisingly, there was no significant difference in the ability of peritoneal exudate cells from gp91phox-/-/NOS2-/-, NOS2-/-, gp91phox-/-, or immunocompetent C57BL/6 mice to kill C. albicans in vitro. This suggests that anti-Candida factors other than ROI and RNI can control the growth of C. albicans and that gp91phox-/-/NOS2-/- mice die due to the inability of the host to control its inflammatory response to Candida. Correspondingly, reverse transcription-PCR analysis showed increased expression of the cytokines gamma interferon, tumor necrosis factor alpha, and the chemokines MIP-2 and KC at the site of infection, while interleukin-15 expression remained relatively unchanged between germfree and infected tissues. These studies indicate that defects in ROI and RNI enabled C. albicans to translocate and disseminate to the internal organs, resulting in an uncontrolled immune response, severe pathology, and death; however, ROI and RNI were not required for the killing of phagocytized C. albicans, indicating that other anti-Candida factors either compensate or are sufficient for the killing of phagocytized Candida.

Mariner 1969: Preliminary Results of the Infrared Radiometer Experiment

The thermal energy emitted by Mars was measured in the 8- to 12- and 18- to 25-micrometer bands. The minimum temperature derived for the southern polar cap is 150 degrees K, an indication that the cap is formed by frozen carbon dioxide. No significant temperature fluctuations were detected with a 100-kilometer scale.

Hydrolytic gene expression during oroesophageal and gastric candidiasis in immunocompetent and immunodeficient gnotobiotic mice

To investigate whether host immunocompetence influences hydrolytic gene expression, we compared secretory aspartyl proteinase gene (SAP) and phospholipase B gene (PLB) expression during gastric candidiasis in immunocompetent and defined immunodeficient gnotobiotic mice, by reverse-transcription polymerase chain reaction. The use of immunodeficient gnotobiotic mice with combined defects in T cells and natural killer cells enabled a comprehensive study of virulence gene expression in various mucosal sites during lethal oroesophageal (tongue, palate, and esophagus) and gastric candidiasis. All 10 SAP and both PLB genes were expressed in both immunocompetent and specific immunodeficient mice, which suggests that the absence of important components of the host defense did not alter gene expression during gastric candidiasis. Although similar patterns of gene expression were evident in different oral tissues, we detected specific differences between Candida albicans-infected oroesophageal and gastric tissues and differences at various time points during the progression of gastric candidiasis.

Development of an engineered bioluminescent reporter phage for detection of bacterial blight of crucifers

Bacterial blight, caused by the phytopathogen Pseudomonas cannabina pv. alisalensis, is an emerging disease afflicting important members of the Brassicaceae family. The disease is often misdiagnosed as pepper spot, a much less severe disease caused by the related pathogen Pseudomonas syringae pv. maculicola. We have developed a phage-based diagnostic that can both identify and detect the causative agent of bacterial blight and differentiate the two pathogens. A recombinant "light"-tagged reporter phage was generated by integrating bacterial luxAB genes encoding luciferase into the genome of P. cannabina pv. alisalensis phage PBSPCA1. The PBSPCA1::luxAB reporter phage is viable and stable and retains properties similar to those of the wild-type phage. PBSPCA1::luxAB rapidly and sensitively detects P. cannabina pv. alisalensis by conferring a bioluminescent signal response to cultured cells. Detection is dependent on cell viability. Other bacterial pathogens of Brassica species such as P. syringae pv. maculicola, Pseudomonas marginalis, Pectobacterium carotovorum, Xanthomonas campestris pv. campestris, and X. campestris pv. raphani either do not produce a response or produce significantly attenuated signals with the reporter phage. Importantly, the reporter phage detects P. cannabina pv. alisalensis on diseased plant specimens, indicating its potential for disease diagnosis.

Some pitfalls in the measurement of blood glutathione

1. We report some pitfalls in the measurement of whole blood and plasma glutathione in man. 2. Using a simple tourniquet to the forearm and a 21-gauge needle, blood samples were collected by brachial vein puncture from healthy subjects. Whole blood and plasma were analysed for total glutathione, including the reduced and oxidized forms, by a spectrophotometric recycling method involving the glutathione reductase/NADPH couple. 3. The concentration of oxidized glutathione was determined after treatment of aliquots with either 2-vinylpyridine or N-ethylmaleimide to trap reduced glutathione. Reduced glutathione in the native samples could then be obtained by subtraction. 4. When the reagents were added to separated plasma, 2-vinylpyridine yielded values for oxidized glutathione that were twice as high as with N-ethylmaleimide. In whole blood studies the discrepancy was even greater, and the problem was not resolved by deproteinization of samples with 5-sulphosalicylic acid. Using N-ethylmaleimide, levels of oxidized glutathione were less than 1% of total glutathione in whole blood. 5. Despite attempts to minimize haemolysis, lysed erythrocytes contributed on average 25% to the 'plasma' glutathione concentration.

Micronutrient antioxidant status in black South Africans with chronic pancreatitis: opportunity for prophylaxis

Biochemical assessments of micronutrient antioxidant status were done in 14 consecutive black patients with calcific chronic pancreatitis and 15 controls at Soweto, near Johannesburg in southern Africa. The patients showed subnormal levels of vitamin C in plasma; selenium, beta-carotene and alpha-tocopherol in serum; and inorganic sulphate (as an index of long-term sulphur amino acid intake) in urine (P < 0.001 for each): furthermore, among the patients ascorbate constituted a lower fraction of vitamin C (P < 0.002), indicating heightened oxidation of the bioactive form. By comparing the results in Sowetan controls with reference ranges from Manchester, UK, the markedly lower vitamin C and, hence, ascorbate levels in the Sowetans was underlined (P < 0.001) and their selenium levels were also lower (P < 0.001), but beta-carotene, alpha-tocopherol and inorganic sulphate levels were comparable. The very low bioavailability of ascorbate among Sowetan controls is reminiscent of our previous finding in outwardly healthy people at Madras in southern India: in both these areas chronic pancreatitis is currently endemic, has a propensity to pancreatic calculi and runs a virulent course towards premature death from diabetes, malnutrition or pancreatic cancer. Considering that low ascorbate levels are a feature in patients with chronic pancreatitis who develop pancreatic calculi at Manchester and that antioxidant supplements ameliorate painful symptoms, we suggest that poor antioxidant intake may predispose underprivileged tropical communities to the disease. If so, there could be an opportunity for prophylaxis through a daily tablet containing vitamin C, perhaps along with selenium at Soweto and beta-carotene at Madras.

Viking infrared thermal mapper

The infrared thermal mapper (IRTM) was designed to measure the emitted and reflected radiance of Mars. Carried by the Viking Orbiter, the IRTM contains four small Cassegrainian telescopes which each image the same, seven circular areas. There is a total of twenty-eight channels in four surface and one atmospheric thermal bands from 6 microm to 30 microm and a broad solar reflectance band. All channels are sampled simultaneously, using the spacecraft scanning capability to map the radiance over small and large areas of the planet. All channels use thermopile detectors; spectral passbands are determined by a combination of interference filters, detector lense materials, antireflection coatings, and restrahlen optics.