Gaussian Process-based prediction of memory performance and biomarker status in ageing and Alzheimer's disease-A systematic model evaluation.

Neuroimaging markers based on Magnetic Resonance Imaging (MRI) combined with various other measures (such as genetic covariates, biomarkers, vascular risk factors, neuropsychological tests etc.) might provide useful predictions of clinical outcomes during the progression towards Alzheimer's disease (AD). The use of multiple features in predictive frameworks for clinical outcomes has become increasingly prevalent in AD research. However, many studies do not focus on systematically and accurately evaluating combinations of multiple input features. Hence, the aim of the present work is to explore and assess optimal combinations of various features for MR-based prediction of (1) cognitive status and (2) biomarker positivity with a multi-kernel learning Gaussian process framework. The explored features and parameters included (A) combinations of brain tissues, modulation, smoothing, and image resolution; (B) incorporating demographics & clinical covariates; (C) the impact of the size of the training data set; (D) the influence of dimensionality reduction and the choice of kernel types. The approach was tested in a large German cohort including 959 subjects from the multicentric longitudinal study of cognitive impairment and dementia (DELCODE). Our evaluation suggests the best prediction of memory performance was obtained for a combination of neuroimaging markers, demographics, genetic information (ApoE4) and CSF biomarkers explaining 57% of outcome variance in out-of-sample predictions. The highest performance for Aß42/40 status classification was achieved for a combination of demographics, ApoE4, and a memory score while usage of structural MRI further improved the classification of individual patient's pTau status.

Colonic Health in Hospitalized Horses Treated with Non-Steroidal Anti-Inflammatory Drugs - A Preliminary Study.

Non-steroidal anti-inflammatory drugs (NSAIDs) can cause right dorsal colitis, but longitudinal clinical studies are lacking. This study investigates whether NSAID treated horses develop right dorsal colonic pathology in a clinical setting. Non-gastrointestinal hospitalized horses treated with NSAIDs >4 days, and untreated hospital-owned teaching horses and non-gastrointestinal client-owned hospitalized horses were included. All horses were monitored over time with clinical examinations (focusing on presence of colic, depression, reduced appetite, unstructured feces), ultrasonographic intestinal wall measurements, fecal occult blood tests (semi-quantitative results), and blood analysis (total protein and albumin concentrations, white blood cell and neutrophil counts). Outcomes were recorded as "ultrasonographically thickened right dorsal colon (RDC) walls", "colitis" and "right dorsal colitis". Findings over time were compared to baseline values and to control horses. Seventeen NSAID treated horses and 5 controls were included. NSAID treated horses developed thickened RDC walls (4/9), and subclinical and mild colitis (9/11) and right dorsal colitis (4/10), whereas all control horses remained healthy. The first changes were identified on treatment day 2. RDC walls of treated horses were significantly thicker compared to their own baseline values and compared to control horses. In conclusion, presumptive colon pathology was identified with a high incidence, starting early in the course of treatment, but with low severity. Appropriate monitoring should be advised throughout NSAID treatment. Additional research for noninvasive diagnostic tests for colon pathology is required.

Cerebral Metabolic Changes Related to Oxidative Metabolism in a Model of Bacterial Meningitis Induced by Lipopolysaccharide.

BACKGROUND: Cerebral mitochondrial dysfunction is prominent in the pathophysiology of severe bacterial meningitis. In the present study, we hypothesize that the metabolic changes seen after intracisternal lipopolysaccharide (LPS) injection in a piglet model of meningitis is compatible with mitochondrial dysfunction and resembles the metabolic patterns seen in patients with bacterial meningitis. METHODS: Eight pigs received LPS injection in cisterna magna, and four pigs received NaCl in cisterna magna as a control. Biochemical variables related to energy metabolism were monitored by intracerebral microdialysis technique and included interstitial glucose, lactate, pyruvate, glutamate, and glycerol. The intracranial pressure (ICP) and brain tissue oxygen tension (PbtO2) were also monitored along with physiological variables including mean arterial pressure, blood glucose, lactate, and partial pressure of O2 and CO2. Pigs were monitored for 60 min at baseline and 240 min after LPS/NaCl injection. RESULTS: After LPS injection, a significant increase in cerebral lactate/pyruvate ratio (LPR) compared to control group was registered (p = 0.01). This increase was due to a significant increased lactate with stable and normal values of pyruvate. No significant change in PbtO2 or ICP was registered. No changes in physiological variables were observed. CONCLUSIONS: The metabolic changes after intracisternal LPS injection is compatible with disturbance in the oxidative metabolism and partly due to mitochondrial dysfunction with increasing cerebral LPR due to increased lactate and normal pyruvate, PbtO2, and ICP. The metabolic pattern resembles the one observed in patients with bacterial meningitis. Metabolic monitoring in these patients is feasible to monitor for cerebral metabolic derangements otherwise missed by conventional intensive care monitoring.

Outbreak of Tuberculosis in a Colony of Rhesus Monkeys (Macaca mulatta) after Possible Indirect Contact with a Human TB Patient.

Simian tuberculosis is one of the most important bacterial diseases of non-human primates. Outbreaks of tuberculosis have been reported in primate colonies almost as long as these animals have been used experimentally or kept in zoological gardens. Significant progress has been made in reducing the incidence of tuberculosis in captive non-human primates, but despite reasonable precautions, outbreaks continue to occur. The most relevant reason is the high incidence of tuberculosis (TB) amongst the human population, in which tuberculosis is regarded as an important re-emerging disease. Furthermore, many non-human primate species originate from countries with a high burden of human TB. Therefore, Mycobacterium tuberculosis remains a significant threat in animals imported from countries with high rates of human infection. We report an outbreak of tuberculosis among a group of rhesus monkeys (Macaca mulatta) living in a closed, long-term colony. The outbreak coincided with reactivation of a TB infection in a co-worker who never had direct access to the animal house or laboratories. Eleven of 26 rhesus monkeys developed classical chronic active tuberculosis with typical caseous granulomata of varying size within different organs. The main organ system involved was the lung, suggesting an aerosol route of infection. Such an outbreak has significant economic consequences due to animal loss, disruption of research and costs related to disease control. Precautionary measures must be improved in order to avoid TB in non-human primate colonies.

Competitive displacement of sodium caseinate by low-molecular-weight emulsifiers and the effects on emulsion texture and rheology.

Low-molecular-weight (LMW) emulsifiers are used to promote controlled destabilization in many dairy-type emulsions in order to obtain stable foams in whippable products. The relation between fat globule aggregation induced by three LMW emulsifiers, lactic acid ester of monoglyceride (LACTEM), saturated monoglyceride (GMS), and unsaturated monoglyceride (GMU) and their effect on interfacial protein displacement was investigated. It was found that protein displacement by LMW emulsifiers was not necessary for fat globule aggregation in emulsions, and conversely fat globule aggregation was not necessarily accompanied by protein displacement. The three LMW emulsifiers had very different effects on emulsions. LACTEM induced shear instability of emulsions, which was accompanied by protein displacement. High stability was characteristic for emulsions with GMS where protein was displaced from the interface. Emulsions containing GMU were semisolid, but only low concentrations of protein were detected in the separated serum phase. The effects of LACTEM, GMS, and GMU may be explained by three different mechanisms involving formation of interfacial α-gel, pickering stabilization and increased exposure of bound casein to the water phase. The latter may facilitate partial coalescence. Stabilizing hydrocolloids did not have any effect on the LMW emulsifiers' ability to induce protein displacement.

Expression patterns of CD44 and CD44 splice variants in patients with rheumatoid arthritis.

OBJECTIVES: It has been suggested that CD44 is involved in the pathogenesis of rheumatoid arthritis (RA). By alternative splicing, numerous CD44 isoforms can be generated which may play different roles the inflammatory process. We therefore studied the expression of various CD44 splicevariants in the circulation and synovial tissue of patients with RA and correlated expression with clinical features. METHODS: Expression of distinct CD44 splice variants was analysed by FACS in peripheral monocytes of 46 RA patients and 36 healthy controls. Expression of CD44 splice variants in synovial tissue of RA and OA patients was analysed by immunohistochemistry and the effects of blocking CD44v4 on RA-fibroblast like synoviocytes (FLS) were studied. RESULTS: On monocytes, the expression of CD44 and CD44v3 was significantly lower in patients with erosive disease than in those without radiographic progression (p<0.05 for CD44 and p<0.01 for CD44v3). CD44v6 on monocytes was significantly associated with the clinical disease activity index (r=0.34, p<0.05) and CRP-levels (r=0.37, p<0.02). Immunhistochemical analyses revealed that most variants were expressed to a significantly higher extent in RA than in OA synovial membranes. Particularly the variants CD44v4, CD44v6 and CD44v7-8 were highly expressed in the RA lining and also abundantly in the endothelium. Blocking CD44v4 in RA-FLS reduced the proliferation to 68±8% (p<0.02) when compared to control experiments and led to a reduction in IL-1ß mRNA expression (p<0.05). CONCLUSIONS: Expression of CD44 splice variants is generally increased in the synovial lining of RA patients when compared to OA. The inverse association of CD44v3 expression on monocytes with the development of erosive disease and the functional impacts of CD44v4 blockade in RA-FLS suggests a pathogenetic role of this splice variants which needs to be further investigated.

Stabilization of visual responses through cholinergic activation.

Neuronal processing of sensory information requires that rapidly changing synaptic inputs are continuously transformed into action potentials. Variability of spike firing is generally considered as noise and might therefore interfere with the reliability of synaptic transmission in sensory systems. In a system in which the number of spikes is a variable that determines the quality of neuronal transmission, variability of spike counts is a paradoxical attribute. In contrast, in a system in which precisely correlated spike firing can influence synaptic integration, response variability might be used as an additional mechanism for coding information. As acetylcholine has been shown to reduce spike-frequency adaptation and enhance gamma frequency (21-70 Hz) oscillations, we set out to study the influence of cholinergic modulation on the variability of spike counts and gamma oscillations. Iontophoretic application of carbachol, a cholinergic agonist, in cat primary visual cortex or electrical stimulation of the mesencephalic reticular formation reduced the spike count variability and stabilized gamma frequency oscillations of visually induced responses. Response stabilization was correlated with enhancement of gamma-frequency oscillations but not with averaged firing rates. Lowering variability of sensory responses might be a mechanism to stabilize and improve reliability of neuronal transmission. Cholinergic activation may therefore influence the efficacy of neuronal transmission by modulating the precise timing of neuronal responses.

Use of complementary and alternative treatment for allergic contact dermatitis.

BACKGROUND: Previous studies show that use of complementary and alternative medicine (CAM) is frequent among dermatological patients in general and that the use of CAM is linked to disease severity and duration. OBJECTIVES: To investigate factors influencing the use of CAM and visits to alternative practitioners among patients with allergic contact dermatitis. METHODS: The study was a postal questionnaire survey among 485 patients with allergic contact dermatitis to fragrances and preservatives in consumer products. The questionnaire included questions about use of conventional treatment, use of CAM and visits to alternative therapists. It also included questions about eczema severity and duration as well as social factors. The patients were recruited from one dermatological clinic in the capital city area and two clinics in smaller cities. RESULTS: The response rate was 79%. Forty per cent of respondents were users of CAM, predominantly in combination with conventional treatment, and 29% had visited an alternative practitioner. Women were found to be significantly more frequent users of CAM and visitors to alternative practitioners than men, and patients from urban/rural districts reported more frequent use of CAM than patients from the capital city area. Frequent eczema eruptions, hand eczema, long duration of disease and work-related problems were positively associated with use of CAM and/or visits to alternative practitioners. CONCLUSIONS: The typical CAM user is female, lives in a rural district or town (not the capital area), has long disease duration and often work-related problems. Overall, the use of CAM is not an alternative to conventional treatment, but is a supplement.

Serum and plasma fragments of C-telopeptides of type I collagen (CTX) are stable during storage at low temperatures for 3 years.

BACKGROUND: Control of pre-analytical variables is essential for successful application of biological markers, including bone resorption markers, in clinical trials and routine use. The effect of storage temperature on stability of bone resorption markers have not been subject of systematically investigation, and therefore the present study was set out to determine the stability of C-telopeptides of type I collagen (CTX) in serum and plasma samples stored frozen for 3 years. METHODS: The serum and plasma levels of CTX were determined in samples aliquoted and stored frozen for up to 3 years. RESULTS: No significant decrease could be detected in neither serum nor plasma samples after 3 years of storage at -20, -80 or -150 degrees C. However, at elevated temperature, i.e. 4 and 37 degrees C, improved stability of CTX was observed in EDTA plasma samples compared to serum. CONCLUSIONS: CTX is stable in frozen serum and plasma samples for up to 3 years. EDTA plasma might be the preferred matrix due to improved stability at elevated temperatures.

Applications of a HOUDINI-based structure elucidation system.

SESAMI, a comprehensive program for the elucidation of the structure of complex compounds of carbon, incorporates a structure reduction-based structure genearator (COCOA). Observed limitations with this program in the solution of higher molecular weight unknowns prompted the development of a structure generator (HOUDINI) which embodies a new concept, convergent structure generation. A comparison of the performance of COCOA-based and HOUDINI-based SESAMI using a set of complex, naturally occurring compounds as a test set of unknowns revealed faster execution times and more efficient processing of ambiguous structural information for the latter.

HOUDINI: a new approach to computer-based structure generation.

A new method of structure generation called convergent structure generation has been developed to address limitations of earlier methods. The features of the program (HOUDINI) based on this method include the following: a single integrated representation of the collective substructural information; the use of parallel atom groups for efficient processing of families of alternative substructural inferences; and a managed structure generation procedure designed to build required structural features early in the process.

A novel formalism to characterize the degree of unsaturation of organic molecules.

The existing formalism to calculate the degree of unsaturation from the molecular formula of organic molecules cannot be applied to charged and/or disconnected species. Moreover, the calculated value depends on the assumed formal valence of each of the elements. In this work, we introduce a new formalism that eliminates these problems. The suggested property, degree of unsaturation, can be calculated from the molecular formula as well as from any structural representation of a molecule corresponding to that molecular formula.

Performance of whole blood IFN-gamma test for tuberculosis diagnosis based on PPD or the specific antigens ESAT-6 and CFP-10.

OBJECTIVE: To evaluate the QuantiFERON-TB test in BCG-vaccinated, non-BCG-vaccinated and tuberculosis (TB) patient donor groups, and to compare its diagnostic performance with that of a blood test based on the Mycobacterium tuberculosis specific antigens ESAT-6 and CFP-10. DESIGN: Analysis of the IFN-gamma responses of whole blood cells from BCG-vaccinated or non-BCG-vaccinated donors or patients with tuberculosis, stimulated with PPD, ESAT-6 or CFP-10 antigens, and evaluation of the specificity and sensitivity of the test. RESULTS: None of the non-vaccinated donors showed positive responses to M. tuberculosis-PPD, ESAT-6 or CFP-10. In BCG-vaccinated donors, 9/19 (47%) donors responded to the QuantiFERON-TB test based on M. tuberculosis-PPD, whereas 2/19 (10.5%) responded to either ESAT-6 or CFP-10. Comparable levels of sensitivity were obtained with the QuantiFERON-TB test based on M. tuberculosis-PPD (79%) and ESAT-6 or CFP-10 antigens (72%). CONCLUSION: Our results demonstrate that the whole blood test based on M. tuberculosis-PPD did not efficiently distinguish BCG-vaccinated donors from individuals with disease due to M. tuberculosis. The introduction of new recombinant antigens specific for M. tuberculosis, such as ESAT-6 or CFP-10, should increase the specificity of the whole blood test and enable discrimination between TB infection, atypical mycobacterial reactivity and reactivity due to BCG vaccination. Such a test would provide a quantum improvement over the current practice of using the tuberculin skin test for TB control and elimination.

Increased numbers of ESAT-6- and purified protein derivative-specific gamma interferon-producing cells in subclinical and active tuberculosis infection.

Numbers of gamma interferon (IFN-gamma)-producing cells reactive to ESAT-6 antigen were increased in recent converters to purified protein derivative positivity and in tuberculosis patients but not in unvaccinated or Mycobacterium bovis BCG-vaccinated healthy donors. ESAT-6-reactive IFN-gamma-producing cells in recent converters and tuberculosis patients recognized similar synthetic peptides. Thus, ESAT-6 is a potential candidate for use in detection of early, as well as active, tuberculosis and for control of the disease.

Ultrasound screening in the 2nd trimester. The pregnant woman's background knowledge, expectations, experiences and acceptances.

OBJECTIVE: Ultrasound screening in the second trimester is widely used in maternal health care. To secure the pregnant woman's autonomy, it is essential to obtain information relating to her understanding and wishes as a starting point for the provision of information. The aim of the study was to explore the pregnant woman's background knowledge, expectations, experiences, and acceptances of second trimester ultrasound screening. DESIGN: Five-hundred consecutive, unselected pregnant woman, of gestational age between 16 and 20 weeks were asked to fill in a questionnaire containing defined and open ended questions. RESULTS: Approximately 70% of the women recruited had undergone a pregnancy-related ultrasound examination previously. Ninety percent answered that they had received information, either from the family doctor or as written material from the hospital (or both), concerning the purpose of the examination. Literature/newspaper/TV, family and friends played an important role as sources for general information. The pregnant women wished to undertake the ultrasound examination to ensure that the fetus was alive, healthy and without any malformation. Few answers were clinically irrelevant. The womens' expectations were fulfilled in 96% of cases, 86% felt 'more secure' after the examination while 2% did not have their expectations fulfilled. Only 0.8% felt more insecure after the examination. The vast majority of both pregnant women and their partners reported a positive experience from the event. CONCLUSION: Pregnant women have a good knowledge of ultrasound examination although the quality of information could be improved. Expectations are fulfilled and are clinically relevant. The acceptability and experiences of the examination are very high.

Specific immune-based diagnosis of tuberculosis.

Current diagnostic tests for tuberculosis based on tuberculin have poor specificity, and both BCG vaccination and exposure to non-tuberculosis mycobacteria produce a response similar to that induced by infection with Mycobacterium tuberculosis. The identification of regions of the M. tuberculosis genome that are not present in BCG and non-tuberculous mycobacteria provides a unique opportunity to develop new highly specific diagnostic reagents. We describe the current status of attempts to exploit this information and summarise recent research that has used defined antigens for an accurate and rapid test for tuberculosis infection based on the detection of T cells sensitised to M. tuberculosis either by blood tests in vitro or skin tests in vivo.

High-frequency oscillations (20 to 120 Hz) and their role in visual processing.

Oscillatory firing of neurons in response to visual stimuli has been observed to occur with different frequencies at multiple levels of the visual system. In the cat retina, oscillatory firing patterns occur with frequencies in the range of 60 to 120 Hz (omega-oscillations). These millisecond-precise temporal patterns are transmitted reliably to the cortex and may provide a feed-forward mechanism of response synchronization. In the cortex, visual responses often show oscillatory patterning with frequencies between 20 and 60 Hz (gamma-oscillations), which are not phase locked to the stimulus onset and therefore do not show up in regularly averaged evoked potentials. Gamma-oscillatory responses synchronize with millisecond precision over long distances and are mediated by the reciprocal corticocortical connectivity. Modulatory systems like the ascending reticular activating system facilitate synchronization and increase the strength of gamma-oscillations. During states of such functional cortical activation, the dominant frequency of the EEG is shifted from lower frequencies in the delta-/theta-range to higher frequencies in the gamma-range. Therefore, functional states indicate different degrees of temporal precision with which large neuronal populations interact. Response synchronization also depends on relations of global stimulus features. This suggests that millisecond-precise neuronal interactions serve as a fundamental mechanism for visual information processing.

Isolated congenital absence of the pericardium: clinical presentation, diagnosis, and management.

BACKGROUND: Congenital absence of the pericardium (CAP) is a rare clinical entity. METHODS: We identified from the two hospital databases all patients with isolated CAP, reviewed their data, and invited them for prospective clinical evaluation with electrocardiography, chest x-ray findings (CXR), echocardiography, and magnetic resonance imaging (MRI). RESULTS: Ten patients (3 males, 7 females) presented at a median age of 21 years (range, 2-53 years) with paroxysmal stabbing chest pain, largely nonexertional (9), and heart murmur with an abnormal CXR (1). Three patients had partial and 7 had complete CAP (all 7 had marked lateral displacement of the cardiac apex). CXR combined with MRI were key to establishing the diagnosis; a "tongue" of lung tissue interposing between the main pulmonary artery and aorta was the most consistent diagnostic feature. Four patients underwent pericardioplasty, 3 for debilitating symptoms and 1 for left atrial appendage herniation, followed by improvement or resolution of symptoms. At a mean of 10.5 years from presentation all patients were alive. No complications were seen in the nonsurgical group. CONCLUSIONS: Isolated CAP has a common presentation pattern with periodic stabbing chest pain mimicking coronary artery disease. CXR and MRI are required for definitive diagnosis. Symptomatic patients with the complete form may benefit from pericardioplasty.

Definitive palliation with cavopulmonary or aortopulmonary shunts for adults with single ventricle physiology.

OBJECTIVE: To compare the relative merits of cavopulmonary or aortopulmonary shunts, or both, as definitive non-Fontan palliations for patients with single ventricle physiology. DESIGN: Clinical data, ECG, echocardiographic data, surgical records, and available postmortem material were reviewed in all patients with single ventricle physiology identified from the University of Toronto Congenital Cardiac Centre for Adults (UTCCCA) database who had not undergone a Fontan operation. Current status of patients was assessed from clinic reviews and patient contact. Two groups of patients were identified: those with cavopulmonary shunt (group 1, n = 35); and those with aortopulmonary shunt(s) only (group 2, n = 15). RESULTS: 50 adults (21 male/29 female) who underwent the last palliation at a median age of 11 years (range 1 day to 53 years) were identified. During a mean (SD) follow up of 13.0 (6.2) years at the UTCCCA, 19 patients died. Survival is 89.4% and 51.9% at 10 and 20 years, respectively, from the time patients were first seen at UTCCCA, with no differences between the groups. Most recent New York Heart Association (NYHA) classification was I-II in 21 patients, III in 25, and IV in four patients; mean haemoglobin was 190 (28) g/l, and oxygen saturation was 82 (4)%, with no group differences. Arrhythmia developed in 25 patients (atrial flutter/fibrillation in 20 and/or sustained ventricular tachycardia in 11). Atrial flutter/fibrillation was more common in patients in group 2, who also showed a greater decline in ventricular function with time. Age at last palliation, cardiothoracic ratio, and inclusion in group 2 were predictive of atrial flutter/fibrillation, poor ventricular function predictive of ventricular tachycardia, NYHA class > III, and prior ventricular tachycardia predictive of death. CONCLUSIONS: Cavopulmonary or aortopulmonary shunts, or both, provide sustained palliation for selected patients with single ventricle physiology. Survival for both compares favourably with published Fontan series. Compared to aortopulmonary shunts, cavopulmonary shunts convey a beneficial long term effect on ventricular function. Arrhythmia is a major cause of late morbidity in these patients, relating to both ventricular dysfunction and death. Onset of sustained ventricular tachycardia is an ominous sign.