Categorical classifiers in multiclass classification with imbalanced datasets

This paper discusses, in a multiclass classification setting, the issue of the choice of the so-called categorical classifier, which is the procedure or criterion that transforms the probabilities produced by a probabilistic classifier into a single category or class. The standard choice is the Bayes Classifier (BC), but it has some limits with rare classes. This paper studies the classification performance of the BC versus two alternatives, that are the Max Difference Classifier (MDC) and Max Ratio Classifier (MRC), through an extensive simulation and some case studies. The results show that both MDC and MRC are preferable to BC in a multiclass setting with imbalanced data

Spectrum of aerobic bacteria and their antimicrobial pattern in blood stream infections of hospitalised patients: a retrospective study

Background: Bacteria associated with blood stream infections are an important public health problem which results in morbidity and mortality globally. Emergence of multidrug resistant isolates in hospitalized patients is a major problem. Automation techniques play a major role in early identification of the isolate and its drug susceptibility testing which is important for better outcome of the treatment. This study was aimed to detect the blood stream isolates and their drug susceptibility pattern in hospitalized patients.Methods: This was a retrospective study conducted from 377 records of automated blood culture (bact/alert) and drug susceptibility testing (vitek) results. Positive blood culture bottles were sub cultured to different culture media and the isolates were identified and screened for drug susceptibility testing on Vitek II.Results: Around 20.68% of samples were positive for blood stream infections caused by different pathogens. A total of 78 microorganisms were isolated from 377 samples. Among which gram negative bacilli was observed in 52.56%, gram positive cocci in 44.87% and yeast in 2.56% samples. Coagulase negative staphylococci and Klebsiella pneumoniae were the predominant isolates of the study.Conclusions: Early diagnosis of blood stream infections in hospitalized patients is life saving. Hence a continuous monitoring of isolates and their drug susceptibility is the need of the day

KCa3.1 inhibition switches the phenotype of glioma-infiltrating microglia/macrophages

Among the strategies adopted by glioma to successfully invade the brain parenchyma is turning the infiltrating microglia/macrophages (M/MΦ) into allies, by shifting them toward an anti-inflammatory, pro-tumor phenotype. Both glioma and infiltrating M/MΦ cells express the Ca(2+)-activated K(+) channel (KCa3.1), and the inhibition of KCa3.1 activity on glioma cells reduces tumor infiltration in the healthy brain parenchyma. We wondered whether KCa3.1 inhibition could prevent the acquisition of a pro-tumor phenotype by M/MΦ cells, thus contributing to reduce glioma development. With this aim, we studied microglia cultured in glioma-conditioned medium or treated with IL-4, as well as M/MΦ cells acutely isolated from glioma-bearing mice and from human glioma biopsies. Under these different conditions, M/MΦ were always polarized toward an anti-inflammatory state, and preventing KCa3.1 activation by 1-[(2-Chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34), we observed a switch toward a pro-inflammatory, antitumor phenotype. We identified FAK and PI3K/AKT as the molecular mechanisms involved in this phenotype switch, activated in sequence after KCa3.1. Anti-inflammatory M/MΦ have higher expression levels of KCa3.1 mRNA (kcnn4) that are reduced by KCa3.1 inhibition. In line with these findings, TRAM-34 treatment, in vivo, significantly reduced the size of tumors in glioma-bearing mice. Our data indicate that KCa3.1 channels are involved in the inhibitory effects exerted by the glioma microenvironment on infiltrating M/MΦ, suggesting a possible role as therapeutic targets in glioma

Modeling viral and drug kinetics: Hepatitis C virus treatment with pegylated interferon alfa-2b

Administration of peginterferon alfa-2b plus ribavirin results in an early hepatitis C virus (HCV) RNA decay followed by an increase as the drug concentration declines between doses. Upon administration of the next dose 1 week later, the same pattern is observed. We have incorporated pharmacokinetic/pharmacodynamic analysis into a model of viral dynamics to describe the effect that changes in drug concentration and effectiveness can have on viral levels. To illustrate the relationship between pharmacokinetics and viral dynamics, we fit the model to data from four HCV/human immunodeficiency virus co-infected patients, and obtained good agreement with the measured serum HCV RNA levels. We were able to account for the observed increases in HCV RNA, and estimate virion and drug half-lives that are in agreement with previous reports. Models incorporating pharmacokinetics are needed to correctly interpret viral load changes and estimate drug effectiveness in treatment protocols using peginterferon alfa-2b

Executive function abnormalities in pathological gamblers

Background: Pathological gambling (PG) is an impulse control disorder characterized by persistent and maladaptive gambling behaviors with disruptive consequences for familial, occupational and social functions. The pathophysiology of PG is still unclear, but it is hypothesized that it might include environmental factors coupled with a genetic vulnerability and dysfunctions of different neurotransmitters and selected brain areas. Our study aimed to evaluate a group of patients suffering from PG by means of some neuropsychological tests in order to explore the brain areas related to the disorder. Methods: Twenty outpatients (15 men, 5 women), with a diagnosis of PG according to DSM-IV criteria, were included in the study and evaluated with a battery of neuropsychological tests: the Wisconsin Card Sorting Test (WCST), the Wechsler Memory Scale revised (WMS-R) and the Verbal Associative Fluency Test (FAS). The results obtained in the patients were compared with normative values of matched healthy control subjects. Results: The PG patients showed alterations at the WCST only, in particular they had a great difficulty in finding alternative methods of problem-solving and showed a decrease, rather than an increase, in efficiency, as they progressed through the consecutive phases of the test. The mean scores of the other tests were within the normal range. Conclusion: Our findings showed that patients affected by PG, in spite of normal intellectual, linguistic and visual-spatial abilities, had abnormalities emerging from the WCST, in particular they could not learn from their mistakes and look for alternative solutions. Our results would seem to confirm an altered functioning of the prefrontal areas which might provoke a sort of cognitive "rigidity" that might predispose to the development of impulsive and/or compulsive behaviors, such as those typical of PG. © 2008 Marazziti et al; licensee BioMed Central Ltd

RenalGuard system in high-risk patients for contrast-induced acute kidney injury.

BACKGROUND: High urine flow rate (UFR) has been suggested as a target for effective prevention of contrast-induced acute kidney injury (CI-AKI). The RenalGuard therapy (saline infusion plus furosemide controlled by the RenalGuard system) facilitates the achievement of this target. METHODS: Four hundred consecutive patients with an estimated glomerular filtration rate ≤30 mL/min per 1.73 m(2) and/or a high predicted risk (according to the Mehran score ≥11 and/or the Gurm score >7%) treated by the RenalGuard therapy were analyzed. The primary end points were (1) the relationship between CI-AKI and UFR during preprocedural, intraprocedural, and postprocedural phases of the RenalGuard therapy and (2) the rate of acute pulmonary edema and impairment in electrolytes balance. RESULTS: Urine flow rate was significantly lower in the patients with CI-AKI in the preprocedural phase (208 ± 117 vs 283 ± 160 mL/h, P 0.32 mg/kg (HR 5.03, 95% CI 2.33-10.87, P < .001) were independent predictors of CI-AKI. Pulmonary edema occurred in 4 patients (1%). Potassium replacement was required in 16 patients (4%). No patients developed severe hypomagnesemia, hyponatremia, or hypernatremia. CONCLUSIONS: RenalGuard therapy is safe and effective in reaching high UFR. Mean intraprocedural UFR ≥450 mL/h should be the target for optimal CI-AKI prevention

Local molecular and global connectomic contributions to cross-disorder cortical abnormalities

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The sorin freedom stentless pericardial valve: clinical and echocardiographic performance at 10 years.

Objective: The Sorin Pericarbon Freedom (SPF) is a stentless valve made of pericardium clinically available in 1990. We report the clinical and hemodynamic performance of the SPF at 10 years. Methods: From April 2000 to December 2005, 85 patients with a mean age of 75 \ub1 6 years (range 57-86), underwent aortic valve replacement (AVR) with an SPF. Mean left ventricular ejection fraction was 58 \ub1 10\% (range 29-86\%) and mean peak transvalvular gradient (PG) 86 \ub1 24 mmHg. Clinical evaluation was performed at 3, 6, 12 months, and yearly thereafter. Results: There were 2 operative deaths (2.4\%). Follow-up ranged from 2 to 135 months (mean 78 \ub1 32 months) and was 99\% complete. There were 35 late deaths, 7 of which were valve-related, with an actuarial survival of 45 \ub1 8\% at 10 years. Structural SPF deterioration occurred in 2 patients, with an actuarial freedom of 96 \ub1 3\%. A total of 4 patients were re-operated, 2 because of structural deterioration, 1 because of endocarditis, and 1 because of sinotubular junction dilatation; freedom from reoperation was 93 \ub1 4\% at 10 years. At last clinical control, 41 patients (89\%) were in NYHA class I or II. Mean SPF effective orifice area varied from 1.55 \ub1 0.66 cm2 for size 21 mm to 2.33 \ub1 0.86 cm2 for size 27 mm; PG varied from 19 \ub1 10 mmHg for size 21 mm to 11 \ub1 6 mmHg for size 27 mm. Left ventricular mass index decreased from 213 \ub1 51 gm/m2 to 157 \ub1 436 gm/m2 (p<0.001). Conclusions: The SPF has demonstrated overall good results in terms of valve durability and freedom from valve-related complications up to 10 years, with excellent hemodynamic performance