Contribution of Clostridium difficile infection to the development of lower gastrointestinal adverse events during autologous stem cell transplantation.

BACKGROUND: Lower gastrointestinal (GI) adverse events (LGAE) are common afflictions of patients undergoing stem cell transplantation (SCT). Unfortunately, the pathophysiology remains poorly characterized. Emerging data suggest a prominent role of intestinal microbiota; however, contributions of pathogenic gut microbiota such as Clostridium difficile are not well defined. We performed a genome-wide association study (GWAS) to investigate clinical and genetic factors associated with development of LGAE. METHODS: A total of 972 patients undergoing autologous SCT were graded for LGAE based on Common Terminology Criteria for Adverse Events (v 4.0). Germline DNA material was obtained from leukapharesis products and genotyped using Illumina(®) Whole Genome Genotyping Infinium chemistry and HumanOmni1-Quad Bead chips containing over 1.1 million single nucleotide polymorphisms (SNPs) (Illumina, San Diego, California, USA). Statistical models incorporating clinical factors, genetic factors, and a combination of clinical plus genetic factors were utilized to compare patients who developed severe LGAE (grade 2 or above) and others. RESULTS: Among 972 patients, 459 (47.2%) developed severe LGAE. Baseline hemoglobin and hematocrit, estimated glomerular filtration rate, ß2-microglobulin, protocol type, and C. difficile infection (CDI) were associated with severe LGAE on univariate analysis, Genomic comparisons between groups did not reveal any SNPs associated with severe LGAE and neither did incorporation of genetic factors into the clinical model. In addition, 11 candidate SNPs associated with upper GI mucositis were evaluated, alongside clinical factors in a multivariate model. Only CDI was found to be associated with severe LGAE in all models. CONCLUSION: CDI is a prominent factor in the development of LGAE in patients undergoing autologous SCT.

Cloning and pharmacological characterization of the dog P2X7 receptor.

BACKGROUND AND PURPOSE: Human and rodent P2X7 receptors exhibit differences in their sensitivity to antagonists. In this study we have cloned and characterized the dog P2X7 receptor to determine if its antagonist sensitivity more closely resembles the human or rodent orthologues. EXPERIMENTAL APPROACH: A cDNA encoding the dog P2X7 receptor was isolated from a dog heart cDNA library, expressed in U-2 OS cells using the BacMam viral expression system and characterized in electrophysiological, ethidium accumulation and radioligand binding studies. Native P2X7 receptors were examined by measuring ATP-stimulated interleukin-1beta release in dog and human whole blood. KEY RESULTS: The dog P2X7 receptor was 595 amino acids long and exhibited high homology (>70%) to the human and rodent orthologues although it contained an additional threonine at position 284 and an amino acid deletion at position 538. ATP possessed low millimolar potency at dog P2X7 receptors. 2'-&3'-O-(4benzoylbenzoyl) ATP had slightly higher potency but was a partial agonist. Dog P2X7 receptors possessed relatively high affinity for a number of selective antagonists of the human P2X7 receptor although there were some differences in potency between the species. Compound affinities in human and dog blood exhibited a similar rank order of potency as observed in studies on the recombinant receptor although absolute potency was considerably lower. CONCLUSIONS AND IMPLICATIONS: Dog recombinant and native P2X7 receptors display a number of pharmacological similarities to the human P2X7 receptor. Thus, dog may be a suitable species for assessing target-related toxicity of antagonists intended for evaluation in the clinic.

Cloning and pharmacological characterization of the guinea pig P2X7 receptor orthologue.

BACKGROUND AND PURPOSE: The human, rat, and mouse P2X(7) receptors have been previously characterized, and in this study we report the cloning and pharmacological properties of the guinea pig orthologue. EXPERIMENTAL APPROACH: A cDNA encoding for the guinea pig P2X(7) receptor was isolated from a guinea pig brain library. The receptor was expressed in U-2 OS cells using the BacMam viral expression system. A monoclonal antibody was used to confirm high levels of cell surface expression and the functional properties were determined in ethidium bromide accumulation studies. KEY RESULTS: The predicted guinea pig protein is one amino acid shorter than the human and rat orthologues and over 70% identical to the rat and human receptors. In contrast to human and rat P2X(7) receptors, 2'-&3'-O-(4benzoylbenzoyl)ATP (BzATP) was a partial agonist of the guinea pig P2X(7) receptor when compared to ATP and acted as an antagonist in some assays. However, as at other species orthologues, BzATP was more potent than ATP. The guinea pig P2X(7) receptor possessed higher affinity for 1-[N,O-bis(5-isoquinoline sulphonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN62), suramin and Coomassie Brilliant Blue than human or rat P2X(7) receptors suggesting that it is pharmacologically different to other rodent or human P2X(7) receptors. CONCLUSIONS AND IMPLICATIONS: The guinea pig recombinant P2X(7) receptor displays a number of unique properties that differentiate it from the human, rat and mouse orthologues and this structural and functional information should aid in our understanding of the interaction of agonists and antagonist with the P2X(7) receptor.

Phenotypic classification of mutants: a tool for understanding ligand binding and activation of muscarinic acetylcholine receptors.

GPCRs (G-protein-coupled receptors) such as the M(1) muscarinic receptor have so far proved recalcitrant to direct structure determination. Nevertheless systematic mutagenesis, particularly alanine scanning, has advanced our understanding of their structure-function relationships. GPCRs exhibit multiple conformational states with different affinities for and abilities to activate their cognate G-proteins. Ligand binding alters these conformational equilibria, thus promoting or inhibiting signalling. Alanine-scanning mutagenesis probes the relative contributions of a particular amino acid side chain to the stability of the ground and activated states of the receptor and its complexes. These determine the phenotype of the mutant receptor. Classification of the phenotypes suggests functional roles for particular amino acid side chains, allowing us to group them accordingly. From a rhodopsin-based homology model of the M(1) mAChR, a coherent view emerges of how these clusters of residues function in ligand anchoring, transduction of binding energy, global structural stabilization and selective stabilization of the ground state or the activated state of the receptor. We can identify differences in ligand-binding modes, and suggest inter- and intra-molecular interactions that are weakened or broken, or formed or intensified during acetylcholine-induced activation. In due course, we may be able to extend these insights to activation by unconventional agonists.

Application of a solvent-tolerant microbial consortium for biofiltration of extremely high concentration gaseous solvent streams.

The aerobic biological oxidation of 2-propanol (isopropyl alcohol, IPA) at extremely high concentrations in air by an enriched solvent-tolerant microbial consortium operating at ambient temperature was evaluated for six months. Solvent-tolerant microbial cells were immobilised onto porous glass pall rings and fed with either IPA or its metabolic product acetone as sole carbon source. Successful biofiltration of solvent vapour at a concentration of 24 g m(-3) was achieved with oxidation of up to 100% total inlet carbon. The maximum IPA mass loading and IPA elimination capacity (EC) was 1700 g m(-3) h(-1). This performance exceeds all previous values published in the literature for similar processes. A slip feed experiment, using acetone, was also performed in order to assess the substrate specificity performance. The biofilter responded successfully to a switch from acetone to IPA as sole carbon source, displaying little reduction in overall organic carbon removal.

Ultrasonication as a pre-treatment method for the enhancement of the psychrophilic anaerobic digestion of aquaculture effluents.

The effectiveness of ultrasonication as a pre-treatment method for the psychrophilic anaerobic treatment of aquaculture effluents was assessed using a 4 l solids digester. Ultrasonication of aquaculture wastewater was found to enhance the removal of chemical oxygen demand by anaerobic digestion by almost 10%. There was also a concurrent increase in total biogas production from 0.29 l day(-1) to 0.45 l day(-1) with a corresponding 10% increase in methane concentration. Furthermore, there was an increase of 60% in effluent total ammonia nitrogen concentration as a result of sonication in comparison with a 45% increase for untreated digester waste.

A further study of the anaerobic biotreatment of malt whisky distillery pot ale using an UASB system.

Pot ale from a pilot-scale malt whisky distillery was treated using a mesophilic upflow anaerobic sludge blanket (UASB) digester. Stable operation was observed at organic loading rates (OLRs) of 5.46 kg COD/m3 day or less when the pot ale was diluted with tap water. Digester failure occurred when undiluted pot ale was used, even though OLR was less than 5 kg COD/m3 day. Overall performance was worse than that observed previously when UASB digesters were used to treat pot ale from a different source supplemented with trace elements. A substantial proportion of effluent chemical oxygen demand (COD) was present as volatile fatty acids (VFA), particularly during periods of reactor stress, indicating that overall performance was limited by the rate of VFA conversion. Wastewater alkalinity rose during digestion. The sludge which developed in the reactor was flocculent but did not form compact granules.

Pneumosinus dilatans of the sphenoid sinus presenting with visual loss.

OBJECTIVE: To report 3 cases of pneumosinus dilatans of the sphenoid sinus associated with visual loss. MATERIALS AND METHODS: Retrospective case series describing history of visual loss, visual examination, visual field deficits, and radiologic imaging. RESULTS: Three patients developed visual loss associated with pneumosinus dilatans of the sphenoid sinus. CONCLUSIONS: Pneumosinus dilatans of the sphenoid sinus is a rare disorder that should be considered in patients presenting with unexplained visual loss.

Biodegradation of propanol and isopropanol by a mixed microbial consortium.

The aerobic biodegradation of high concentrations of 1-propanol and 2-propanol (IPA) by a mixed microbial consortium was investigated. Solvent concentrations were one order of magnitude greater than any previously reported in the literature. The consortium utilized these solvents as their sole carbon source to a maximum cell density of 2.4 x 10(9) cells ml(-1). Enrichment experiments with propanol or IPA as carbon sources were carried out in batch culture and maximum specific growth rates (mumax) calculated. At 20 degrees C, mumax values were calculated to be 0.0305 h(-1) and 0.1093 h(-1) on 1% (v/v) IPA and 1-propanol, respectively. Growth on propanol and IPA was carried out between temperatures of 10 degrees C and 45 degrees C. Temperature shock responses by the microbial consortium at temperatures above 45 degrees C were demonstrated by considerable cell flocculation. An increase in propanol substrate concentration from 1% (v/v) to 2% (v/v) decreased the mumax from 0.1093 h(-1) to 0.0715 h(-1). Maximum achievable biodegradation rates of propanol and IPA were 6.11 x 10(-3)% (v/v) h(-1) and 2.72 x 10(-3)% (v/v) h(-1), respectively. Generation of acetone during IPA biodegradation commenced at 264 h and reached a maximum concentration of 0.4% (v/v). The results demonstrate the potential of mixed microbial consortia in the bioremediation of solvent-containing waste streams.

Predictors of visual acuity and the relative afferent pupillary defect in optic neuropathy.

The relationships among visual acuity (log MAR), diagnostic category, age, the magnitude of a relative afferent pupillary defect (RAPD) in log units, photopic foveal thresholds to white and colored light (dB), and the mean deviation on the Humphrey visual field (dB) were studied in patients with various optic neuropathies. All acuity and dB values were expressed as interocular differences, the majority of cases having normal acuity in the fellow eye. In multiple regression analyses, acuity and RAPD were alternately chosen as the dependent or response variable with all remaining variables serving as the predictors or independent variables. The main finding was that the only significant predictor of a RAPD was the interocular mean deviation difference on the Humphrey field and the only significant predictor of acuity was the foveal threshold to white light. Redundant and insignificant variables were therefore identified with multiple regression analysis. Subsidiary findings include: (a) although diagnostic group was not a significant predictor in the above, simple linear regression line slopes relating RAPD magnitude to the Humphrey mean deviation were significantly different between optic neuritis and compression categories; (b) for a given level of acuity, foveal thresholds were substantially worse in these cases with neuronal damage than in strabismic amblyopia, refractive error, or corneal damage; and (c) sensitivity losses for red vs. blue light were similar.

Orbital and optic pathway sarcoidosis: MR findings.

PURPOSE: To identify and characterize the MR findings of sarcoidosis when it involves the orbit and visual pathways. METHODS: The MR scans of 15 patients, 3 with presumed and 12 with proved orbital or optic pathway sarcoidosis were retrospectively reviewed. RESULTS: Eight patients had MR evidence of optic nerve involvement by sarcoid granuloma. Perineural enhancement was seen in four cases, optic atrophy in one. Three who had had unenhanced scans showed optic nerve enlargement. Nine patients had optic chiasmal involvement. One patient had increased T2 signal in the optic radiations. Three patients had orbital masses that had MR signal characteristics similar to pseudotumor. Five patients had periventricular white matter abnormalities closely resembling multiple sclerosis. CONCLUSIONS: Sarcoidosis should be considered in the differential diagnosis of optic nerve or nerve sheath enhancement on MR. Orbital sarcoidosis has MR characteristics very similar to pseudotumor.

Orbital and sinus inflammation with secondary optic neuropathy.

Optic neuropathy with simultaneous orbital and sinus inflammation is a diagnostic dilemma. Although sinus inflammation was described previously as causative in some cases of optic neuritis, the relatively high rate of asymptomatic sinus opacification in radiologic studies of the general population (as high as 13%) makes this a diagnosis of exclusion. We describe a patient who had optic neuropathy associated with simultaneous orbital and sinus inflammation. Although definitive determination of etiology may not be made without tissue biopsy, cases suspected of having a bacterial etiology may benefit from an initial 48-hour trial of intravenous antibiotics before initiation of systemic corticosteroids.

Anterior granulomatous uveitis in patients with multiple sclerosis.

Granulomatous uveitis has infrequently been described as a manifestation of the autoimmune phenomena of multiple sclerosis (MS). The authors describe six cases of anterior granulomatous uveitis in patients with MS. All six patients had features of iridocyclitis and three patients had features of periphlebitis, which were suggestive of granulomatous disease. However, each patient had neurologic symptoms and signs consistent with MS and a negative laboratory workup for sarcoidosis, tuberculosis, and syphilis. Testing for MS in a subgroup of patients with granulomatous uveitis of unknown etiology and neurologic symptoms may result in a diagnosis.

Saccadic latency as a measure of afferent visual conduction.

Latency to initiate a saccadic eye movement to a visual target, and visual evoked potential, were measured in seven patients with resolved unilateral optic neuritis. Saccades were delayed when the target was presented to the clinically involved eye, but were normal when the contralateral eye was tested. With binocular target presentation, saccades were symmetric between eyes and normal in latency. In two patients with pituitary adenoma and low-grade bitemporal field defects, saccades were delayed when targets were presented in the temporal field, but were within normal limits when presented in the nasal field. These results cannot be attributed to lesions in the motor pathways. It is concluded that saccadic latency to visual targets is a valid measure of afferent conduction. If the robust delays found in this study prove to have test-retest reliability, saccadic latency may provide a measure of afferent function which is sensitive to the demyelination that preceeds neuronal degeneration and sensitivity loss in patients suspected of having optic neuropathy.

Blunt popliteal artery trauma: one hundred consecutive injuries.

An institutional experience with 100 consecutive blunt popliteal artery injuries over a 20-year period was reviewed. The overall amputation rate was 15%; however, during the past 7 years this has declined from 23% to 6%. Minimizing delay in the revascularization of ischemic limbs, routine systemic heparinization, primary arterial repair when possible, repair of popliteal venous injuries, aggressive wound debridement, and early soft tissue coverage have contributed to improved limb salvage during the 1980s.

Symptoms of amaurosis fugax in atherosclerotic carotid artery disease.

Amaurosis fugax is a term used to describe transient monocular visual loss due to atherosclerosis of the ipsilateral internal carotid artery. It is differentiated from other causes of transient monocular blindness, especially retinal migraine. It is said that amaurosis fugax episodes are short in duration and only occasionally include "positive" visual phenomena such as scintillations. Monocular migraine is more prolonged and often accompanied by scintillations. We studied 37 patients with amaurosis fugax and angiographic evidence of carotid atherosclerosis ipsilateral to the symptomatic eye. Nearly one-third of the patients had long attacks or positive visual phenomena. In many patients, transient monocular visual loss due to carotid atherosclerosis cannot be differentiated from retinal migraine based on clinical symptoms alone.

Dural sinus thrombosis: a mechanism for pseudotumor cerebri in systemic lupus erythematosus.

We report a young woman with systemic lupus erythematosus complicated by pseudotumor cerebri which resolved with high dosage corticosteroid therapy. The cause of the raised intracranial pressure proved to be thrombosis of the torcular herophili and lateral sinuses. Despite laboratory evidence of a hypercoagulable state, the presence of a lupus anticoagulant could not be shown.

Antiphospholipid antibodies associated with retinal vascular disease.

Two patients with retinal vascular disease also had antiphospholipid antibodies, defined by the presence of the circulating lupus anticoagulant (LAC), anticardiolipin antibodies, or both. One had retinal arterial occlusions and the other had a nonischemic central retinal vein occlusion. The association of thrombotic vascular disease, including both retinal and cerebral vessels, with the presence of these antibodies should be investigated in otherwise normal individuals or in patients presenting with a lupuslike syndrome and retinal vascular occlusive disease. Low-dose aspirin administration could be of therapeutic value in managing thrombotic events in this group of patients.