bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of the susceptibility to oxidative stress by cysteine availability in pancreatic β-cells
Authors: Numazawa Satoshi , Sakaguchi Harumi , Aoki Risa , Taira Toshio , Yoshida Takemi
Published: June 2008

Pancreatic β-cells are susceptible to oxidative stress, which is related closely to the islet dysfunction. In the present study, using the pancreatic cell lines HIT-T15 and RINm5F as known in vitro models of impaired β-cell function as well as primary rat islet β-cells, we observed a relationship between intracellular glutathione levels and oxidative stress-mediated cell dysfunction. Hydrogen peroxide and 4-hydroxy-2-nonenal caused cell death in HIT-T15 and RINm5F cells at lower concentrations compared with non-β-cells, such as HepG2 and NRK-49F cells. The extent of the cytotoxicity caused by the model oxidants was inversely correlated well with intracellular glutathione levels in the cell lines used. Treatment of HIT-T15 and RINm5F cells with l-cysteine or l-cystine significantly augmented the glutathione contents, surpassing the effect of N-acetylcysteine, and abrogated 4-hydroxy-2-nonenal-mediated cytotoxicity almost completely. l-Cysteine increased intracellular glutathione levels in primary β-cells as well. Supplementation of l-cysteine to the RINm5F cell culture inhibited 4-hydroxy-2-nonenal-mediated cytosolic translocation of PDX-1, a key transcription factor for β-cell function. Intrinsic transport activities ( Vmax/ Km) of the l-cystine/l-glutamate exchanger in HIT-T15 and RINm5F cells were considerably lower than that in NRK-49F cells, although gene expressions of the exchanger were similar in these cells. Results obtained from the present study suggest that the restricted activity of the l-cystine/l-glutamate exchanger controls the levels of intracellular glutathione, thereby making β-cells become susceptible to oxidative stress.
Depletion of cellular cholesterol enhances macrophage MAPK activation by chitin microparticles but not by heat-killed Mycobacterium bovis BCG
Authors: Nishiyama Akihito , Shinohara Tsutomu , Pantuso Traci , Tsuji Shoutaro , Yamashita Makiko , Shinohara Shizuka , Myrvik Quentin N. , Henriksen Ruth Ann , Shibata Yoshimi
Published: June 2008

When macrophages phagocytose chitin ( N-acetyl-d-glucosamine polymer) microparticles, mitogen-activated protein kinases (MAPK) are immediately activated, followed by the release of Th1 cytokines, but not IL-10. To determine whether phagocytosis and macrophage activation in response to chitin microparticles are dependent on membrane cholesterol, RAW264.7 macrophages were treated with methyl-β-cytodextrin (MBCD) and stimulated with chitin. These results were compared with the corresponding effects of bacterial components including heat-killed (HK) Mycobacterium bovis bacillus Calmette-Guèrin (BCG) and an oligodeoxynucleotide (ODN) of bacterial DNA (CpG-ODN). The MBCD treatment did not alter chitin binding or the phagocytosis of chitin particles 20 min after stimulation. At the same time, however, chitin-induced phosphorylation of cellular MAPK was accelerated and enhanced in an MBCD dose-dependent manner. The increased phosphorylation was also observed for chitin phagosome-associated p38 and ERK1/2. In contrast, CpG-ODN and HK-BCG induced activation of MAPK in MBCD-treated cells at levels comparable to, or only slightly more than, those of control cells. We also found that MBCD treatment enhanced the production of tumor necrosis factor-α (TNF-α) and the expression of cyclooxygenase-2 (COX-2) in response to chitin microparticles. In neither MBCD- nor saline-treated macrophages, did chitin particles induce detectable IL-10 mRNA synthesis. CpG-ODN induced TNF-α production, and COX-2 expression were less sensitive to MBCD treatment. Among the agonists studied, our results indicate that macrophage activation by chitin microparticles was most sensitive to cholesterol depletion, suggesting that membrane structures integrated by cholesterol are important for physiological regulation of chitin microparticle-induced cellular activation.
Teleost fish osmoregulation: what have we learned since August Krogh, Homer Smith, and Ancel Keys
Authors: Evans David H.
Published: June 2008

In the 1930s, August Krogh, Homer Smith, and Ancel Keys knew that teleost fishes were hyperosmotic to fresh water and hyposmotic to seawater, and, therefore, they were potentially salt depleted and dehydrated, respectively. Their seminal studies demonstrated that freshwater teleosts extract NaCl from the environment, while marine teleosts ingest seawater, absorb intestinal water by absorbing NaCl, and excrete the excess salt via gill transport mechanisms. During the past 70 years, their research descendents have used chemical, radioisotopic, pharmacological, cellular, and molecular techniques to further characterize the gill transport mechanisms and begin to study the signaling molecules that modulate these processes. The cellular site for these transport pathways was first described by Keys and is now known as the mitochondrion-rich cell (MRC). The model for NaCl secretion by the marine MRC is well supported, but the model for NaCl uptake by freshwater MRC is more unsettled. Importantly, these ionic uptake mechanisms also appear to be expressed in the marine gill MRC, for acid-base regulation. A large suite of potential endocrine control mechanisms have been identified, and recent evidence suggests that paracrines such as endothelin, nitric oxide, and prostaglandins might also control MRC function.
Neural Response Properties of Primary, Rostral, and Rostrotemporal Core Fields in the Auditory Cortex of Marmoset Monkeys
Authors: Bendor Daniel , Wang Xiaoqin
Published: June 2008

The core region of primate auditory cortex contains a primary and two primary-like fields (AI, primary auditory cortex; R, rostral field; RT, rostrotemporal field). Although it is reasonable to assume that multiple core fields provide an advantage for auditory processing over a single primary field, the differential roles these fields play and whether they form a functional pathway collectively such as for the processing of spectral or temporal information are unknown. In this report we compare the response properties of neurons in the three core fields to pure tones and sinusoidally amplitude modulated tones in awake marmoset monkeys ( Callithrix jacchus). The main observations are as follows. ( 1) All three fields are responsive to spectrally narrowband sounds and are tonotopically organized. ( 2) Field AI responds more strongly to pure tones than fields R and RT. ( 3) Field RT neurons have lower best sound levels than those of neurons in fields AI and R. In addition, rate-level functions in field RT are more commonly nonmonotonic than in fields AI and R. ( 4) Neurons in fields RT and R have longer minimum latencies than those of field AI neurons. ( 5) Fields RT and R have poorer stimulus synchronization than that of field AI to amplitude-modulated tones. ( 6) Between the three core fields the more rostral regions (R and RT) have narrower firing-rate–based modulation transfer functions than that of AI. This effect was seen only for the nonsynchronized neurons. Synchronized neurons showed no such trend.
Applying He′s Variational Iteration Method for Solving Differential‐Difference Equation
Authors: Yıldırım Ahmet
Published: June 2008

We extend He′s variational iteration method (VIM) to find the approximate solutions for nonlinear differential‐difference equation. Simple but typical examples are applied to illustrate the validity and great potential of the generalized variational iteration method in solving nonlinear differential‐difference equation. The results reveal that the method is very effective and simple. We find the extended method for nonlinear differential‐difference equation is of good
accuracy.
Targeting of sonic hedgehog-GLI signaling: a potential strategy to improve therapy for mantle cell lymphoma
Authors: Hegde Ganapati V. , Munger Corey M. , Emanuel Katy , Joshi Avadhut D. , Greiner Timothy C. , Weisenburger Dennis D. , Vose Julie M. , Joshi Shantaram S.
Published: June 2008

Mantle cell lymphoma (MCL) has one of the worst clinical outcomes among the B-cell lymphomas, with a median survival of only 3 to 4 years. Therefore, a better understanding of the underlying mechanisms that regulate MCL proliferation/survival is needed to develop an effective therapy. Because sonic hedgehog (Shh)-GLI signaling has been shown to be important in the proliferation and survival of several cancers, and no such information is available for MCL, this study was undertaken. Our results show that the molecules associated with Shh-GLI signaling, such as PTCH and SMO receptors, and GLI1 and GLI2 target transcription factors were expressed in the human MCL cell lines and primary MCL cells from patients. Perturbation of this signaling in the presence of exogenous Shh/cyclopamine significantly (P < 0.001) influenced the proliferation of JVM2 MCL cells. Furthermore, down-regulation of GLI transcription factors using antisense oligonucleotides not only resulted in significantly (P < 0.001) decreased proliferation of the MCL cells but also significantly (P < 0.05) increased their susceptibility to chemotherapeutic drug, doxorubicin. Also, down-regulation of GLI decreased cyclin D1 and BCL2 transcript levels, which suggests that these key molecules might be regulated by GLI in MCL. Thus, our results indicate a significant role for Shh-GLI signaling in the proliferation of MCL, and molecular targeting of GLI is a potential therapeutic approach to improve the treatment for MCL. [Mol Cancer Ther 2008;7(6):1450–60]
How Should We Manage Pain in Ventilated Neonates?
Authors: Menon Gopi , McIntosh Neil
Published: June 2008

Newborn babies, even if extremely preterm, show responses to pain. The major stress responses seen with surgical pain are associated with serious adverse medical outcomes. There is an ethical imperative to consider pain relief in babies, despite the fact that they cannot verbalise their experience. Ventilator support, and accompanying treatments are described as distressing in adults, and are associated with an endocrine stress response in babies. Opiates have been shown to reduce physiological instability in sick newborn babies. Despite this, they have not been shown to reduce morbidity when given by infusion in ventilated infants, and in view of their serious side effects probably should not be used routinely in this way. It is logical and may be appropriate to give opiates peri-operatively and in babies likely to have severe pain (either from an underlying disease process such as necrotising enterocolitis, or during certain procedures). It is now accepted practice to use a potent analgesic/sedative for elective intubation and as cover for the treatment of retinopathy of prematurity. Topical anaesthetic creams reduce the pain response when used in anticipation of phlebotomy or vascular cannulation. Intra-oral sucrose is effective cover for procedures associated with mild to moderate distress, but its role in preterm infants is uncertain. Nursing interventions to reduce environmental stress, although commonly used, have not consistently been shown to be of benefit.
Cell-Mediated Immune Responses to Complex and Single Mycobacterial Antigens in Tuberculosis Patients with Diabetes
Authors: Mustafa Abu S. , El-Shamy Abdulsalam M. , Madi Nada M. , Amoudy Hanady A. , Al-Attiyah Rajaa
Published: June 2008

Objective: To evaluate cell-mediated immune (CMI) response in diabetic and non-diabetic tuberculosis (TB) patients and healthy subjects in response to complex, fractionated and single antigens of Mycobacteriumtuberculosis. Material and Methods: Peripheral blood mononuclear cells (PBMC) were obtained from patients suffering from pulmonary TB and type II diabetes (n = 7), pulmonary TB without diabetes (n = 10) and healthy subjects without TB and diabetes (n = 10). PBMC were assessed for CMI responses in antigen-induced proliferation assays in response to complex mycobacterial antigens (whole cells, cell walls and culture filtrate of M. tuberculosis), a battery of naturally purified or recombinant produced secreted (ESAT6, MPT59, MPT64 and MTB38) and cytosolic (MTB10, MTB70, ML10, ML28, ML36, ML65 and MB65) mycobacterial antigens and fractionated culture filtrate proteins (fractions F1–F10) of M. tuberculosis. Results:The majority (>70%) of diabetic and non-diabetic TB patients and healthy subjects responded to the complex antigens of M. tuberculosis. However, among the single antigens, ESAT6 was most frequently recognized by TB patients with and without diabetes, but least recognized by healthy subjects. The secreted antigens MPT59 and MPT64 were recognized by all the groups, whereas the cytosolic antigens were recognized best by healthy subjects. When tested with fractionated secreted proteins present in the culture filtrate of M. tuberculosis, the best responses in both diabetic and non-diabetic TB patients were obtained with fractions containing low-molecular-weight proteins. Conclusions: Diabetic and non-diabetic TB patients respond frequently to secreted low-molecular-weight ESAT6 antigen of M. tuberculosis, indicating that this antigen may be useful in the diagnosis of TB in both the groups.
Characterization of Folded Recombinant Der p 5, a Potential Diagnostic Marker Allergen for House Dust Mite Allergy
Authors: Weghofer Margit , Grote Monika , Dall’Antonia Yuliya , Fernández-Caldas Enrique , Krauth Maria-Theresa , van Hage Marianne , Horak Friedrich , Thomas Wayne R. , Valent Peter , Keller Walter , Valenta Rudolf , Vrtala Susanne
Published: June 2008

Background: Der p 5 was reported as an important allergen in Dermatophagoides pteronyssinus, which is particularly recognized by patients suffering from asthma. The aim of this study was to produce, by recombinant DNA technology, a folded Der p 5 allergen for diagnostic, therapeutic and preventive purposes. Methods: Der p 5-encoding cDNA was isolated from a λgt11 D. pteronyssinus expression cDNA library and expressed in Escherichia coli. rDer p 5 was purified to homogeneity and characterized by mass spectroscopy and circular dichroism. IgE reactivity was tested with sera from 117 mite-allergic patients and in a basophil histamine release experiment. Der p 5-specific rabbit IgG antibodies were produced for the ultrastructural localization of the allergen in mites by immunogold electron microscopy as well as for cross-reactivity studies. Results: rDer p 5 is a heat-stable protein with predominantly α-helical secondary structure which reacted with IgE from 31% of mite-allergic patients’ sera and showed no relevant cross-reactivity to group 5 allergens from storage mites and tropical mites. rDer p 5-specific rabbit IgG antibodies inhibited mite-allergic patients’ IgE binding to Der p 5 and allowed to localize the allergen in secretory granules of midgut epithelial cells of house dust mites. Conclusions: The described rDer p 5 molecule may be useful for diagnosis and immunotherapy of house dust mite-allergic patients.
Smoking and Risk of Cedar Pollinosis in Japanese Men and Women
Authors: Nagata Chisato , Nakamura Kozue , Fujii Kaori , Kawachi Toshiaki , Takatsuka Naoyoshi , Oba Shino , Shimizu Hiroyuki
Published: June 2008

Background: Pollinosis induced by the cedar pollen antigen is the most common seasonal allergic reaction in Japan. We aimed to examine the relationship between smoking and risk of cedar pollinosis in a population-based cohort of the Japanese. Methods: Study subjects were 12,221 men and women from the Takayama Study cohort who were 35–69 years old at enrollment in 1992. A follow-up survey in 2002 was used to obtain information about four symptoms related to cedar pollinosis. Results: A total of 1,000 subjects had cedar pollinosis during the 10-year follow-up. As compared with those who had never smoked, current smokers at the baseline were at a significantly decreased risk of cedar pollinosis after controlling for covariates in men (hazard ratio [HR]: 0.64, 95% CI: 0.50–0.83) as well as in women (HR: 0.64, 95% CI: 0.47–0.88). There was a significant dose-response relationship between the risk of cedar pollinosis and the number of cigarettes smoked each day as well as with the number of years an individual had smoked. A significant risk reduction was observed among men and women who had continued to smoke cigarettes during the follow-up period in comparison with those who had never smoked. There was no risk increase for former smokers at the baseline as well as for those who quit smoking during the follow-up. Conclusions: Some components of tobacco may protect against cedar pollinosis. Our finding could provide clues about therapeutic strategies for protection against cedar pollinosis.
Sequence Analysis of BIRC4/XIAP in Male Patients with Common Variable Immunodeficiency
Authors: Salzer Ulrich , Hagena Tina , Webster David B. , Grimbacher Bodo
Published: June 2008

Background: Common variable immunodeficiency (CVID) is the most common primary antibody deficiency syndrome in humans, but it remains a diagnosis of exclusion in most cases. Several genetically defined primary immunodeficiencies mimic CVID. Among them is the X-linked lymphoproliferative syndrome (XLP) which was shown to be caused by either mutations in the gene SH2D1a/SAP or, more recently, in the BIRC4/XIAP gene. Methods: We therefore analyzed a cohort of 28 male CVID patients and 2 patients with an IgG subclass deficiency for the prevalence of mutations in BIRC4, encoding for XIAP by direct sequencing. Results: All patients showed a wild-type sequence of BIRC4/XIAP. Two SNPs, rs5956583 (dbSNP126) located in exon 6 (P→Q) and rs28382740 (dbSNP126) in the 3′ untranslated region were observed at the same frequencies as reported in public databases. Conclusions: We found no patient with a defect in the coding sequence of BIRC4/XIAP in our cohort of 30 hypogammaglobulinemic patients. We therefore estimate that XLP caused by XIAP deficiency may be a very rare differential diagnosis in male patients with CVID.
Ventricular Tachycardia Originating From the Posterior Papillary Muscle in the Left Ventricle
Authors: Doppalapudi Harish , Yamada Takumi , McElderry H. Thomas , Plumb Vance J. , Epstein Andrew E. , Kay G. Neal
Published: June 2008

Background—

Several distinct forms of focal ventricular tachycardia (VT) from the left ventricle (LV) have been described. We report a new syndrome of VT arising from the base of the posterior papillary muscle in the LV.

Methods and Results—

Among 290 consecutive patients who underwent ablation for VT or symptomatic premature ventricular complexes (PVCs) based on a focal mechanism, 7 patients were found to have an ablation site at the base of the posterior papillary muscle in the LV. All patients had normal LV systolic function and a normal baseline electrocardiogram. The electrocardiogram during VT or PVCs demonstrated a right bundle-branch block and superior-axis QRS morphology in all patients. VT was not inducible by programmed atrial or ventricular stimulation. In 2 patients with sustained VT, overdrive pacing neither terminated VT nor demonstrated any criterion for transient entrainment. Activation mapping localized the earliest site of activation to the base of the posterior papillary muscle in all patients. When Purkinje potentials were recorded at the site of successful ablation, these potentials preceded local ventricular muscle potentials during sinus rhythm. During VT or PVCs, however, the ventricular muscle potential always preceded the Purkinje potentials. After recurrence of VT or PVCs with standard radiofrequency ablation, irrigated ablation was successful in eliminating the arrhythmia in all patients. Over a mean follow-up period of 9 months, all patients have been free of PVCs and VT.

Conclusion—

We present a distinct syndrome of VT arising from the base of the posterior papillary muscle in the LV by a nonreentrant mechanism. Ablation can be challenging, and irrigated ablation may be necessary for long-term success.
Effects of the Oral Direct Renin Inhibitor Aliskiren in Patients With Symptomatic Heart Failure
Authors: McMurray John J.V. , Pitt Bertram , Latini Roberto , Maggioni Aldo P. , Solomon Scott D. , Keefe Deborah L. , Ford Jessica , Verma Anil , Lewsey Jim
Published: June 2008

Background—

Loss of negative feedback inhibition of renin release during chronic treatment with an angiotensin-converting enzyme (ACE) inhibitor leads to a compensatory rise in renin secretion and downstream components of the renin-angiotensin-aldosterone (RAAS) cascade. This may overcome ACE inhibition but should be blocked by a direct renin inhibitor. We studied the effects of adding the direct renin inhibitor aliskiren to an ACE inhibitor in patients with heart failure.

Methods and Results—

Patients with New York Heart Association class II to IV heart failure, current or past history of hypertension, and plasma brain natriuretic peptide (BNP) concentration >100 pg/mL who had been treated with an ACE inhibitor (or angiotensin receptor blocker) and β-blocker were randomized to 3 months of treatment with placebo (n=146) or aliskiren 150 mg/d (n=156). The primary efficacy outcome was the between-treatment difference in N-terminal pro-BNP (NT-proBNP). Patients’ mean age was 68 years, mean ejection fraction was 31%, and mean�SD systolic blood pressure was 129�17.4 mm Hg. Sixty-two percent of the patients were in New York Heart Association functional class II, and 33% were taking an aldosterone antagonist. Plasma NT-proBNP rose by 762�6123 pg/mL with placebo and fell by 244�2025 pg/mL with aliskiren (
P
=0.0106). BNP and urinary (but not plasma) aldosterone were also reduced by aliskiren. Clinically important differences in blood pressure and biochemistry were not seen between aliskiren and placebo.

Conclusions—

Addition of aliskiren to an ACE inhibitor (or angiotensin receptor blocker) and β-blocker had favorable neurohumoral effects in heart failure and appeared to be well tolerated.
Admission or Changes in Renal Function During Hospitalization for Worsening Heart Failure Predict Postdischarge Survival
Authors: Klein Liviu , Massie Barry M. , Leimberger Jeffrey D. , O’Connor Christopher M. , Piña Ileana L. , Adams Kirkwood F. , Califf Robert M. , Gheorghiade Mihai
Published: June 2008

Background—

Admission measures of renal function (blood urea nitrogen [BUN], estimated glomerular filtration rate [eGFR]) in patients hospitalized for worsening heart failure are predictors of in-hospital outcomes. Less is known about the changes and relationships among these variables and the postdischarge survival rate.

Methods and Results—

In a retrospective analysis of 949 patients from the Outcomes of a Prospective Trial of Intravenous Milrinone for Exacerbations of Chronic Heart Failure, we investigated the relation between admission values and changes in BUN and eGFR and rate of death by 60 days after discharge. On admission, median eGFR was 51 mL � min
−1
� 1.73 m
−2
(interquartile range, 37 to 70 mL � min
−1
� 1.73 m
−2
), and BUN was 25 mg/dL (interquartile range, 17 to 41 mg/dL). On average, there was a 1.1–mL � min
−1
� 1.73 m
−2
decrease in eGFR and a 4.7-mg/dL increase in BUN from admission to discharge. By discharge, 12% of patients had a >25% decrease in eGFR, and 39% had a >25% increase in BUN. Although both lower admission eGFR and higher admission BUN were associated with higher risk of death by 60 days after discharge, multivariable-adjusted Cox proportional-hazards analysis showed that BUN was a stronger predictor of death by 60 days than was eGFR (χ
2
, 11.6 and 0.6 for BUN and eGFR, respectively). Independently of admission values, an increase of ≥10 mg/dL in BUN during hospitalization was associated with worse 60-day survival rate: BUN (per 5-mg/dL increase) had a hazard ratio of 1.08 (95% CI, 1.01 to 1.16). Although milrinone treatment led to a minor improvement in renal function by discharge, the 60-day death and readmission rates were similar between the milrinone and placebo groups.

Conclusions—

A substantial number of patients admitted with heart failure have worsening renal function during hospitalization. Higher admission BUN and increasing BUN during hospitalization, independently of admission values, are associated with a worse survival rate. Use of milrinone in these high-risk patients does not improve outcomes despite minor improvements in the renal function.
Challenges for the Basis of Practice in Heart Failure
Authors: Stevenson Lynne Warner
Published: June 2008

Although evidence from clinical trials has significantly informed the management of patients with heart failure, many patients and many clinical situations encountered on a daily basis do not fit neatly into the narrow definitions of trials. In subsequent issues,
Circulation: Heart Failure
will feature a new series entitled “Challenges for the Basis of Practice,” in which readers may submit challenging cases that call for management considerations and decisions that extend well beyond the evidence. An expert consultant will be invited to comment, and readers can also submit responses to these challenging situations so that numerous viewpoints can be explored.
Nuclear Shape, Mechanics, and Mechanotransduction
Authors: Dahl Kris Noel , Ribeiro Alexandre J.S. , Lammerding Jan
Published: June 2008

In eukaryotic cells, the nucleus contains the genome and is the site of transcriptional regulation. The nucleus is the largest and stiffest organelle and is exposed to mechanical forces transmitted through the cytoskeleton from outside the cell and from force generation within the cell. Here, we discuss the effect of intra- and extracellular forces on nuclear shape and structure and how these force-induced changes could be implicated in nuclear mechanotransduction, ie, force-induced changes in cell signaling and gene transcription. We review mechanical studies of the nucleus and nuclear structural proteins, such as lamins. Dramatic changes in nuclear shape, organization, and stiffness are seen in cells where lamin proteins are mutated or absent, as in genetically engineered mice, RNA interference studies, or human disease. We examine the different mechanical pathways from the force-responsive cytoskeleton to the nucleus. We also highlight studies that link changes in nuclear shape with cell function during developmental, physiological, and pathological modifications. Together, these studies suggest that the nucleus itself may play an important role in the response of the cell to force.
Boosting Method for Local Learning in Statistical Pattern Recognition
Authors: Kawakita Masanori , Eguchi Shinto
Published: June 2008

We propose a local boosting method in classification problems borrowing from an idea of the local likelihood method. Our proposal, local boosting, includes a simple device for localization for computational feasibility. We proved the Bayes risk consistency of the local boosting in the framework of Probably approximately correct learning. Inspection of the proof provides a useful viewpoint for comparing ordinary boosting and local boosting with respect to the estimation error and the approximation error. Both boosting methods have the Bayes risk consistency if their approximation errors decrease to zero. Compared to ordinary boosting, local boosting may perform better by controlling the trade-off between the estimation error and the approximation error. Ordinary boosting with complicated base classifiers or other strong classification methods, including kernel machines, may have classification performance comparable to local boosting with simple base classifiers, for example, decision stumps. Local boosting, however, has an advantage with respect to interpretability. Local boosting with simple base classifiers offers a simple way to specify which features are informative and how their values contribute to a classification rule even though locally. Several numerical studies on real data sets confirm these advantages of local boosting.
Gamma Oscillations in a Nonlinear Regime: A Minimal Model Approach Using Heterogeneous Integrate-and-Fire Networks
Authors: Bathellier Brice , Carleton Alan , Gerstner Wulfram
Published: June 2008

Fast oscillations and in particular gamma-band oscillation (20–80 Hz) are commonly observed during brain function and are at the center of several neural processing theories. In many cases, mathematical analysis of fast oscillations in neural networks has been focused on the transition between irregular and oscillatory firing viewed as an instability of the asynchronous activity. But in fact, brain slice experiments as well as detailed simulations of biological neural networks have produced a large corpus of results concerning the properties of fully developed oscillations that are far from this transition point. We propose here a mathematical approach to deal with nonlinear oscillations in a network of heterogeneous or noisy integrate-and-fire neurons connected by strong inhibition. This approach involves limited mathematical complexity and gives a good sense of the oscillation mechanism, making it an interesting tool to understand fast rhythmic activity in simulated or biological neural networks. A surprising result of our approach is that under some conditions, a change of the strength of inhibition only weakly influences the period of the oscillation. This is in contrast to standard theoretical and experimental models of interneuron network gamma oscillations (ING), where frequency tightly depends on inhibition strength, but it is similar to observations made in some in vitro preparations in the hippocampus and the olfactory bulb and in some detailed network models. This result is explained by the phenomenon of suppression that is known to occur in strongly coupled oscillating inhibitory networks but had not yet been related to the behavior of oscillation frequency.
Neural Integrator: A Sandpile Model
Authors: Nikitchenko Maxim , Koulakov Alexei
Published: June 2008

We investigated a model for the neural integrator based on hysteretic units connected by positive feedback. Hysteresis is assumed to emerge from the intrinsic properties of the cells. We consider the recurrent networks containing either bistable or multistable neurons. We apply our analysis to the oculomotor velocity-to-position neural integrator that calculates eye positions using the inputs that carry information about eye angular velocity. By analyzing this system in the parameter space, we show the following. The direction of hysteresis in the neuronal response may be reversed for the system with recurrent connections compared to the case of unconnected neurons. Thus, for the NMDA receptor-based bistability, the firing rates after ON saccades may be higher than after OFF saccades for the same eye position. The reversal of hysteresis occurs in this model only when the size of hysteresis differs from neuron to neuron. We also relate the macroscopic leak time constant of the integrator to the rate of microscopic spontaneous noise-driven transitions in the hysteretic units. Finally, we investigate the conditions under which the hysteretic integrator may have no threshold for integration.
Classification of Tropical Precipitating Systems Using Wind Profiler Spectral Moments. Part I: Algorithm Description and Validation
Authors: Rao T. Narayana , Kirankumar N. V. P. , Radhakrishna B. , Rao D. Narayana , Nakamura K.
Published: June 2008

The lower atmospheric wind profiler (LAWP) measurements made at Gadanki, India, have been used to develop an objective algorithm to classify the tropical precipitating systems. A detailed investigation on the existing classification scheme reveals major shortcomings in the scheme. In the present study, it is shown with examples that the Doppler velocity gradient (DVG) criterion is a necessary but certainly not a sufficient condition to identify the radar bright band. Such gradients in Doppler velocity can exist in other types of rain systems, for example, in convection, due to the modulation of Doppler velocity of hydrometeors by vertical air motion. The approach of the new classification scheme deviates considerably from that of existing algorithms. For instance, the new algorithm, in contrast to identifying the stratiform rain and assuming the remaining rain as convection, identifies first convection and later stratiform precipitation based on their specific characteristics. The other interesting feature in this algorithm is that it was built on the strengths of other potential classification schemes and theoretically accepted thresholds for classification of the precipitation. The performance of the new algorithm has been verified with the help of time–height maps of profiler moments and corresponding surface rainfall patterns.
Classification of Tropical Precipitating Systems Using Wind Profiler Spectral Moments. Part II: Statistical Characteristics of Rainfall Systems and Sensitivity Analysis
Authors: Rao T. Narayana , Kirankumar N. V. P. , Radhakrishna B. , Rao D. Narayana , Nakamura K.
Published: June 2008

An automated precipitation algorithm to classify tropical precipitating systems has been described in a companion paper (Part I). In this paper, the algorithm has been applied to 18 months of lower atmospheric wind profiler measurements to study the vertical structure and statistical features of different types of tropical precipitating systems over Gadanki, India. The shallow precipitation seems to be an important component of tropical precipitation, because it is prevalent for about 23% of the observations, with a rainfall fraction of 16%. As expected, the deep convective systems contribute maximum (60%) to the total rainfall, followed by transition and stratiform precipitation. Nonprecipitating clouds (clouds associated with no surface rainfall) are predominant in transition category, indicating that evaporation of precipitation is significant in this region. The quantitative rainfall statistics in different precipitation regimes are compared and contrasted between themselves and also with those reported at different geographical locations obtained with a wide spectrum of instruments, from rain gauges to profilers and scanning radars. The results herein agree with the reports based on scanning radar measurements but differ from profiler-based statistics. The discrepancies are discussed in light of differences in classification schemes, variation in geographical conditions, etc. The sensitivity of the algorithm on the choice of thresholds for identifying different types of precipitating systems is also examined.
Optimal Compression of High Spectral Resolution Satellite Data via Adaptive Vector Quantization with Linear Prediction
Authors: Huang Bormin , Ahuja Alok , Huang Hung-Lung
Published: June 2008

Contemporary and future high spectral resolution sounders represent a significant technical advancement for environmental and meteorological prediction and monitoring. Given their large volume of spectral observations, the use of robust data compression techniques will be beneficial to data transmission and storage. In this paper, a novel adaptive vector quantization (VQ)-based linear prediction (AVQLP) method for lossless compression of high spectral resolution sounder data is proposed. The AVQLP method optimally adjusts the quantization codebook sizes to yield the maximum compression on prediction residuals and side information. The method outperforms the state-of-the-art compression methods [Joint Photographic Experts Group (JPEG)-LS, JPEG2000 Parts 1 and 2, Consultative Committee for Space Data Systems (CCSDS) Image Data Compression (IDC) 5/3, Context-Based Adaptive Lossless Image Coding (CALIC), and 3D Set Partitioning in Hierarchical Trees (SPIHT)] and achieves a new high in lossless compression for the standard test set of 10 NASA Atmospheric Infrared Sounder (AIRS) granules. It also compares favorably in terms of computational efficiency and compression gain to recently reported adaptive clustering methods for lossless compression of high spectral resolution data. Given its superior compression performance, the AVQLP method is well suited to ground operation of high spectral resolution satellite data compression for rebroadcast and archiving purposes.
Application of the Sequential Three-Dimensional Variational Method to Assimilating SST in a Global Ocean Model
Authors: He Zhongjie , Xie Yuanfu , Li Wei , Li Dong , Han Guijun , Liu Kexiu , Ma Jirui
Published: June 2008

A recursive filter or parameterized curve fitting technique is usually used in a three-dimensional variational data assimilation (3DVAR) scheme to approximate the background error covariance, which can only represent the errors of an ocean field over a predetermined scale. Without an accurate flow-dependent error covariance that is also local and time dependent, a 3DVAR system may not provide good analyses because it is optimal only under the assumption of an accurate covariance. In this study, a sequential 3DVAR (S3DVAR) is formulated in model grid space to examine if there is useful information that can be extracted from the observation. This formulation is composed of a series of 3DVARs, each of which uses recursive filters with different length scales. It can provide an inhomogeneous and anisotropic analysis for the wavelengths that can be resolved by the observation network, just as with the conventional Barnes analysis or successive corrections. Being a variational formulation, S3DVAR can deal with data globally with an explicit specification of the observation errors; explicit physical balances or constraints; and advanced datasets, such as satellite and radar. Even though the S3DVAR analysis can be viewed as a set of isotropic functions superpositioned together, this superposition is not prespecified as in a single 3DVAR approach but is determined by the information that can be resolved by observation. The S3DVAR is adopted in a global sea surface temperature (SST) data assimilation system, into which the shipboard SSTs and the 4-km Advanced Very High Resolution Radiometer (AVHRR) Pathfinder daily SSTs are assimilated, respectively. The results demonstrate that the proposed S3DVAR works better in practice than a single 3DVAR.
Alongfront Variability of Precipitation Associated with a Midlatitude Frontal Zone: TRMM Observations and MM5 Simulation
Authors: Han Mei , Braun Scott A. , Persson P. Ola G. , Bao Jian-Wen
Published: June 2008

On 19 February 2001, the Tropical Rainfall Measuring Mission (TRMM) satellite observed complex alongfront variability in the precipitation structure of an intense cold-frontal rainband. The TRMM Microwave Imager brightness temperatures suggested that, compared to the northern and southern ends of the rainband, a greater amount of precipitation ice was concentrated in the middle portion of the rainband where the front bowed out. A model simulation conducted using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) is examined to explain the distribution of precipitation associated with the cold-frontal rainband. The simulation reveals that the enhanced precipitation ice production and the implied mean ascent along the central part of the front were associated with a synergistic interaction between a low-level front and an upper-level front associated with an intrusion of high-PV stratospheric air. The low-level front contributed to an intense bow-shaped narrow cold-frontal rainband (NCFR). The upper-level front was dynamically active only along the central to northern portion of the NCFR, where the upper-level PV advection and Q-vector convergence were most prominent. The enhanced mean ascent associated with the upper-level front contributed to a wide cold-frontal rainband (WCFR) that trailed or overlapped with the NCFR along its central to northern segments. Because of the combination of the forcing from both lower- and upper-level fronts, the ascent was deepest and most intense along the central portion of the front. Thus, a large concentration of precipitation ice, attributed to both the NCFR and WCFR, was produced.
Mortality Rates and Causes of Death of Convicted Dutch Criminals 25 Years Later
Authors: Nieuwbeerta Paul , Piquero Alex R.
Published: June 2008

Extant theory hypothesizes that offenders have greater risk of premature and unnatural death than nonoffenders, but few studies have assessed this hypothesis; those doing so have relied on U.S. samples of male offenders typically followed until midlife. This article examines the relation between criminal conduct and mortality rates in the Netherlands using data from the Criminal Careers and Life Course Study, which traces the life course and criminal careers of 4,615 males and females convicted in 1977 up until 2002. The causes of deaths that occurred during this 25-year period are examined using data from the Netherlands Statistics. Results show that criminal conduct increases the chance of premature death due to natural and unnatural causes. Convicted persons run greater risks of dying of unnatural causes such as accidents, homicide, and suicide. Additionally, risk of premature, unnatural death varies, with high-rate, persistent offenders evincing higher risks than other types of offenders.
Population Pharmacokinetics of Oseltamivir When Coadministered With Probenecid
Authors: Rayner Craig R. , Chanu Pascal , Gieschke Ronald , Boak Lauren M. , Jonsson E. Niclas
Published: June 2008

Oseltamivir is a potent, selective, oral neuraminidase inhibitor for the treatment and prophylaxis of influenza. Plasma concentrations of the active metabolite, oseltamivir carboxylate, are increased in the presence of probenecid, suggesting that the combination could allow for the use of reduced doses of oseltamivir. To investigate this proposal, we developed a population pharmacokinetic model and simulated the pharmacokinetics of candidate combination regimens of oral oseltamivir (45 mg and 30 mg twice a day) plus oral probenecid (500 mg/6 hourly). Probenecid plus oseltamivir 45 mg achieved all the pharmacokinetic parameters expected of oseltamivir alone, but combination with oseltamivir 30 mg and dose interval extension approaches did not. An oseltamivir—probenecid combination may compromise tolerability and enhance the potential for drug interactions. In addition, increased dosing requirements may affect compliance and attainment of optimal oseltamivir exposure, potentially facilitating the emergence of viral strains with reduced susceptibility to oseltamivir. These factors, set alongside increased capacity for oseltamivir production, should be carefully considered before an oseltamivir—probenecid combination is used.
Community College Faculty What We Know and Need to Know
Authors: Twombly Susan , Townsend Barbara K.
Published: June 2008

This review of existing literature about community college faculty members speculates about why they have received so little scholarly attention, summarizes the nature of existing research, including its methodology and topics, and suggests what else needs to be known about them.
Does the Elimination of Prerequisites Affect Enrollment and Success?
Authors: Abou-Sayf Frank K.
Published: June 2008

The impact of an experimental, one-semester suspension of mathematics and English prerequisites from 12 courses is investigated. Data on enrollment, student performance, and instructor opinions are analyzed for the total group, and results concerning English versus mathematics prerequisites are compared. Implications for further research on the impact of prerequisites are discussed.
Choosing and Using Citation and Bibliographic Database Software (BDS)
Authors: Hernandez David A. , El-Masri Maher M. , Hernandez Cheri Ann
Published: June 2008

The diabetes educator/researcher is faced with a proliferation of diabetes articles in various journals, both online and in print. Keeping track of cited references and remembering how to cite the references in text and the bibliography can be a daunting task for the new researcher and a tedious task for the experienced researcher. The challenge is to find and use a technology, such as bibliographic database software (BDS), which can help to manage this information overload. This article focuses on the use of BDS for the diabetes educator who is undertaking research. BDS can help researchers access and organize literature and make literature searches more efficient and less time consuming. Moreover, the use of such programs tends to reduce errors associated with the complexity of bibliographic citations and can increase the productivity of scholarly publications. The purpose of this article is to provide an overview of BDS currently available, describe how it can be used to aid researchers in their work, and highlight the features of different programs. It is important for diabetes educators and researchers to explore the many benefits of such BDS programs and consider their use to enhance the accuracy and efficiency of accessing and citing references of their research work and publications. Armed with this knowledge, researchers will be able to make informed decisions about selecting BDS which will meet their usage requirements.
What Other's Disappointment May Do to Selfish People: Emotion and Social Value Orientation in a Negotiation Context
Authors: Van Kleef Gerben A. , Van Lange Paul A. M.
Published: June 2008

The authors examined whether individual differences in social value orientation moderate responses to other's expressions of disappointment in negotiation. The literature suggested competing hypotheses: First, prosocials are more responsive to other's disappointment because they have a greater concern for other; second, proselfs are more responsive because they see other's disappointment as a threat to their own outcomes. Results of a computer-mediated negotiation in which a simulated opponent expressed disappointment, no emotion, or anger supported the second prediction: Proselfs conceded more to a disappointed opponent than to a neutral or angry one, whereas prosocials were unaffected by the other's emotion. This effect was mediated by participants' motivation to satisfy the other's needs, which disappointment triggered more strongly in proselfs than in prosocials. Implications for theorizing on emotion, social value orientation, and negotiation are discussed.
New bench test for venous cannula performance assessment
Authors: Abdel-Sayed S , Favre J , Horisberger J , Taub S , Hayoz D , von Segesser LK
Published: June 2008

Cannula design is of prime importance for venous drainage during cardiopulmonary bypass (CPB). To evaluate cannulas intended for CPB, an in vitro circuit was set up with silicone tubing between the test cannula encased in a movable preload reservoir and another static reservoir. The pressure-drop ( ΔP) value (P-drainage – P-preload) was measured using Millar pressure transducers. Flow rate ( Q) was measured using an ultrasound flowmeter. Data display and data recording were controlled using a LabView application, custom made particularly for our experiments. Our results demonstrated that ΔP, Q, and cannula resistance ( ΔP/Q) values were significantly decreased when the cannula diameter was increased for Smart and Medtronic cannulas. Smartcanula® showed 36% and 43% less resistance compared to Medtronic venous and Medtronic femoral cannulas, respectively. The cannula shape (straight- or curved-tips) did not affect the DLP cannula resistance. Out of five cannulas tested, the Smartcanula® outperforms the other commercially available cannulas. The mean ( ΔP/Q) values were 3.3 ± 0.08, 4.07 ± 0.08, 5.58 ± 0.10, 5.74 ± 0.15, and 6.45 ± 0.15 for Smart, Medtronic, Edwards, Sarns, and Gambro cannulas, respectively (two-way ANOVA, p < 0.0001). In conclusion, the present assay allows discrimination between different forms of cannula with high or low lumen resistance.