Stable azole drug resistance associated with a substrain of Candida albicans from an HIV-infected patient

Oral candidiasis is one of the earliest and most frequent complications of a failing immune system in HIV-infected individuals. For several years, oral candidiasis has been treated effectively with azole drugs, the one most frequently used is fluconazole. Unfortunately, extensive use of the drug for treatment and prophylaxis has led to treatment failure in an increasing number of patients. In most of these cases, strains of C. albicans isolated from the infection are less susceptible to fluconazole. The development of azole resistance in strains of C. albicans has been studied biochemically and more recently with molecular techniques. One excellent example of the development of azole resistance in C. albicans has been documented in a series of 17 C. albicans isolates from a single patient over a 2-year period. During this time, the patient experienced 14 episodes of oral candidiasis and was treated with increasing doses of fluconazole. Molecular and biochemical analyses confirms that the isolates are the same strain of C. albicans and that the resistance in these isolates is stable over 600 generations, suggesting that the changes in this strain are genetic in nature. In addition, the development of resistance is correlated with the identification of a substrain or variant of the original strain, as identified by restriction fragment length polymorphism (RFLP) analysis with the moderately repetitive probe, Ca3. The analysis of this series of isolates demonstrates that azole drug resistance is associated with several small genetic changes, each of which contributes to the overall resistance of the strain. Clearly, continual use of azole drugs by a patient can select for genetic changes that render oral candidiasis refractory to treatment.     

Characterization of a factor IX variant with a glycine207 to glutamic acid mutation

Factor IXTaipei9 is a factor IX variant from a hemophilia B patient with reduced levels of circulating protein molecules (cross-reacting material reduced, CRM). This variant contained a glycine (Gly) to glutamic acid (Glu) substitution at the 207th codon of mature factor IX. The functional consequences of the Gly-->Glu mutation in factor IXTaipei9 (IXG207E) were characterized in this study. Plasma-derived IXG207E exhibited a mobility similar to that of normal factor IX on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its specific activity was estimated to be 3.5% that of the purified normal factor IX in a one-stage partial thromboplastin time assay (aPTT). Cleavage of factor IXG207E by factor XIa or factor VIIa-tissue factor complex appeared to be normal. When the calcium-dependent conformational change was examined by monitoring quenching of intrinsic fluorescence, both normal factor IX and IXG207E exhibited equivalent intrinsic fluorescence quenching. Activated factor IXG207E (IXaG207E) also binds antithrombin III equally as well as normal factor IXa. However, aberrant binding of the active site probe p-aminobenzamidine was observed for factor XIa-activated factor IXG207E, indicating that the active site pocket of the heavy chain of factor IXaG207E was abnormal. Moreover, the rate of activation of factor X by factor IXaG207E, as measured in a purified system using chromogenic substrates, was estimated to be 1/40 of that of normal factor IXa. A computer-modeled heavy-chain structure of factor IXa predicts a hydrophobic environment surrounding Gly-207 and this Gly forms a hydrogen bound to the active site serine-365. The molecular mechanism of the Gly-->Glu mutation in factor IXTaipei9 might result in the alteration of the microenvironment of the active site pocket which renders the active site serine-365 inaccessible to its substrate.     

Exogenously administered prostaglandins modulate pulmonary granulomas induced by Schistosoma mansoni eggs

The inflammatory modulating activity of specific prostaglandins has been examined for both immune and foreign-body types of pulmonary granulomas. Lung granuloma formation generated in mice by embolization of Schistosoma mansoni eggs was markedly suppressed by treatment with the stable, functional analog of prostaglandin E, (PGE1), (15-(S)-15-methyl PGE1) while treatment with PGF2 alpha augmented the granulomatous response. Despite marked effects on egg-induced granuloma formation, PGs had no significant effect on the foreign body lesion induced by Sephadex beads. Likewise, PGs had no effect on the primary antibody response to schistosome egg antigens. However, notable derangements in splenic lymphoid populations occurred. While T-cell numbers appeared constant in face of PG treatment, B-cell populations were depressed by methyl-PGE1 and augmented by PGF2 alpha. Further analysis revealed that methyl-PGE1 appeared to suppress both the induction and elicitation phases of the cell-mediated response to schistosome eggs. Cyclophosphamide treatment could partially reverse this suppression, but the induction of suppressor cell activity was not solely responsible for this effect. The possible role and mechanism of PGs as modulators of chronic inflammation is discussed.     

DIAPHRAGMATIC PARALYSIS IN MOTOR NEURONE DISEASE: USE OF NON-INVASIVE INVESTIGATIVE AND THERAPEUTIC TECHNIQUES

SUMMARY Two cases of bilateral diaphragmatic weakness are described in which the condition was the presenting feature of motor neurone disease. Inspiratory muscle strength was assessed by a non-invasive technique involving measurements of pressures generated within the mouth. One patient with severe inspiratory muscle weakness is being treated with domiciliary nasal ventilation and has returned to a good-quality life. The other patient with less severe weakness has thus far required no ventilatory support.     

Multilineage hematopoietic growth factor interleukin 3 and direct activators of protein kinase C stimulate phosphorylation of common substrates

In order to investigate early signal transduction events in myeloid cells, the phosphosubstrates of an interleukin 3 (IL 3)-dependent cell line, FDC-P1, have been analyzed. Using synthetic diacylglycerol as a direct activator of the unique calcium-phospholipid-dependent phosphotransferase protein kinase C (PK-C) and genetically engineered homogeneous IL 3, we have demonstrated a common element to signal transduction events associated with these stimulants. One novel substrate, p68 (68,000 kd), was rapidly phosphorylated in either IL 3- or diacylglycerol-stimulated cells. The phosphorylation of p68 was dose- dependent, with both the physiological ligand and diacylglycerol inducing the same maximal level of phosphorylation. Phosphorylation of p68 occurred in a time-dependent manner analogous to previously described kinetics of PK-C subcellular redistribution in the FDC-P1 cell line. The p68 substrate was also phosphorylated in a cell-free system under conditions designed to activate PK-C. Phosphoamino acid analysis demonstrated that the p68 molecule phosphorylated in intact cells as well as in a calcium-phospho-lipid-dependent cell-free system was phosphorylated on threonine residues, not tyrosine. These data support the hypothesis that the activation of PK-C that occurs after IL 3-receptor interaction which leads to the rapid phosphorylation of cellular proteins is an important element of the signal transduction mechanism in FDC-P1 cells. We propose that phosphorylation of the p68 molecule is a physiochemical marker for the activation of PK-C in myeloid cells, in response to the growth-promoting physiological ligand.     

High frequency of N-ras activation in acute myelogenous leukemia

Using the NIH/3T3 cell transfection assay, activated cellular oncogenes have been detected in around 10% to 20% of human tumors. From a series of DNA preparations from tissues infiltrated with acute myelogenous leukemia (AML), 50% (3/6) caused transformation of NIH/3T3 cells. Thus AML appears to be the human tumor with the highest frequency of oncogenes detected by DNA transfection. In each case the oncogene involved was N-ras, a member of the ras gene family. Biologic and clinical parameters of AML patients with and without N-ras oncogenes in their tumors are discussed.     

CD11c+ Cells Are Required to Prevent Progression from Local Acute Lung Injury to Multiple Organ Failure and Death

To investigate the role of CD11c⁺ cells in endotoxin-induced acute lung injury, wild-type or CD11c-diphtheria toxin receptor transgenic mice were treated with intraperitoneal diphtheria toxin (5 ng/g b.wt.) in the presence or absence of intratracheal lipopolysaccharide (51 μg). Lipopolysaccharide treatment resulted in 100% mortality in CD11c-depleted animals but not in control animals. Analysis of local lung tissue revealed no differences in acute lung injury severity; however, analysis of distal tissues revealed severe damage and necrosis to multiple organs (liver, spleen, and kidneys) in CD11c-diphtheria toxin receptor mice but not in wild-type mice. In addition, dramatic increases in systemic levels of liver enzymes (alanine aminotransferase, 657 U/L, aspartate aminotransferase, 1401 U/L), blood urea (53 mg/dl), and 8-iso-prostaglandin F_2α, a marker of oxidative stress (350 pg/ml), were observed. These data demonstrate that CD11c⁺ cells play a critical role in protecting the organs from systemic injury caused by a pulmonary endotoxin challenge.Acute lung injury (ALI) and acute respiratory distress syndrome are conditions that are characterized by diffuse alveolar injury, subsequent impairment of arterial oxygenation associated with protein leakage into the alveolar space, and high mortality rates.^1–3 Interestingly, despite the severe limitation in gas exchange, the mortality associated with this syndrome is not due to hypoxia but rather to a progressive failure in multiple organ systems (frequently referred to as multiple organ dysfunction syndrome [MODS]).²The majority of injuries precipitating ALI are septic in nature, either due to systemic septicemia or a local pneumonitis that leads to the development of a systemic inflammatory condition.^4,5 Many proinflammatory mediators have been implicated in septic inflammation and MODS including nitric oxide, cytokines, complement factor C5a, and eicosanoids.^2,5 However, to date, trials targeting many of these mediators have been unsuccessful,⁶ generating interest in interventions directed to the cellular rather than humoral components of the inflammatory response in these syndromes.Alveolar macrophages and dendritic cells (DCs) are CD11c⁺ antigen-presenting cells, and the main pathogen-sensing cells of the innate immune system in the lungs.^7–10 These cells rapidly detect and respond to microbial products that are deposited in the lungs.¹⁰ Because of this ability to respond rapidly, these cells are of particular interest. Their responses that can lead to the clearance of the harmful stimuli also can lead to the generation of inflammatory mediators that can promote more profound lung injury.^5,7,8,11,12With the use of CD11c-diphtheria toxin receptor (DTR) mice, transgenic mice that express the diphtheria toxin receptor on CD11c⁺ cells, in the current work we assessed the role of CD11c⁺ cells in controlling a nonlethal endotoxin-induced model of ALI. The CD11c-DTR mice are a robust, well established model that we have previously used to study the role of DCs in Cryptococcus neoformans infections.^7,11,13–16 The results presented here demonstrate that the presence of CD11c⁺ cells is critical in preventing oxidative stress and the progression of mild ALI to a MODS-like syndrome, which rapidly results in death.