bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regression coefficient and autoregressive order shrinkage and selection via the lasso
Authors: Wang Hansheng , Li Guodong , Tsai Chih-Ling 
Published: January 2007

SummaryThe least absolute shrinkage and selection operator (‘lasso’) has been widely used in regression shrinkage and selection. We extend its application to the regression model with autoregressive errors. Two types of lasso estimators are carefully studied. The first is similar to the traditional lasso estimator with only two tuning parameters (one for regression coefficients and the other for autoregression coefficients). These tuning parameters can be easily calculated via a data-driven method, but the resulting lasso estimator may not be fully efficient. To overcome this limitation, we propose a second lasso estimator which uses different tuning parameters for each coefficient. We show that this modified lasso can produce the estimator as efficiently as the oracle. Moreover, we propose an algorithm for tuning parameter estimates to obtain the modified lasso estimator. Simulation studies demonstrate that the modified estimator is superior to the traditional estimator. One empirical example is also presented to illustrate the usefulness of lasso estimators. The extension of the lasso to the autoregression with exogenous variables model is briefly discussed.
Marginal Regression Analysis of Longitudinal Data With Time-Dependent Covariates: A Generalized Method-of-Moments Approach
Authors: Lai Tze Leung , Small Dylan 
Published: January 2007

SummaryWe develop a new approach to using estimating equations to estimate marginal regression models for longitudinal data with time-dependent covariates. Our approach classifies time-dependent covariates into three types—types I, II and III. The type of covariate determines what estimating equations can be used involving the covariate. We use the generalized method of moments to make optimal use of the estimating equations that are made available by the covariates. Previous literature has suggested the use of generalized estimating equations with the independent working correlation when there are time-dependent covariates. We conduct a simulation study that shows that our approach can provide substantial gains in efficiency over generalized estimating equations with the independent working correlation when a time-dependent covariate is of types I or II, and our approach remains consistent and comparable in efficiency with generalized estimating equations with the independent working correlation when a time-dependent covariate is of type III. We apply our approach to analyse the relationship between the body mass index and future morbidity among children in the Philippines.
Widespread neuronal expression of branched‐chain aminotransferase in the CNS: implications for leucine/glutamate metabolism and for signaling by amino acids
Authors: García‐Espinosa María A. , Wallin Reidar , Hutson Susan M. , Sweatt Andrew J. 
Published: January 2007

AbstractTransamination of the branched‐chain amino acids produces glutamate and branched‐chain α‐ketoacids. The reaction is catalyzed by branched‐chain aminotransferase (BCAT), of which there are cytosolic and mitochondrial isoforms (BCATc and BCATm). BCATc accounts for 70% of brain BCAT activity, and contributes at least 30% of the nitrogen required for glutamate synthesis. In previous work, we showed that BCATc is present in the processes of glutamatergic neurons and in cell bodies of GABAergic neurons in hippocampus and cerebellum. Here we show that this metabolic enzyme is expressed throughout the brain and spinal cord, with distinct differences in regional and intracellular patterns of expression. In the cerebral cortex, BCATc is present in GABAergic interneurons and in pyramidal cell axons and proximal dendrites. Axonal labeling for BCATc continues into the corpus callosum and internal capsule. BCATc is expressed by GABAergic neurons in the basal ganglia and by glutamatergic neurons in the hypothalamus, midbrain, brainstem, and dorsal root ganglia. BCATc is also expressed in hypothalamic peptidergic neurons, brainstem serotoninergic neurons, and spinal cord motor neurons. The results indicate that BCATc accumulates in neuronal cell bodies in some regions, while elsewhere it is exported to axons and nerve terminals. The enzyme is in a position to influence pools of glutamate in a variety of neuronal types. BCATc may also provide neurons with sensitivity to nutrient‐derived BCAAs, which may be important in regions that control feeding behavior, such as the arcuate nucleus of the hypothalamus, where neurons express high levels of BCATc.
Dopamine activates Nrf2‐regulated neuroprotective pathways in astrocytes and meningeal cells
Authors: Shih Andy Y. , Erb Heidi , Murphy Timothy H. 
Published: January 2007

AbstractThe transcription factor Nrf2 controls inducible expression of multiple antioxidant/detoxification genes. We previously found that Nrf2‐/‐ mice have increased sensitivity to in vivo mitochondrial stress and ischemia. Although Nrf2 regulated these forms of neuronal toxicity, it was unclear which injury‐triggered signal(s) led to Nrf2 activation in vivo. In this study, we use primary cultures to test the hypothesis that excessive dopamine release can act as an endogenous Nrf2‐inducing signal. We cultured two cell types that show increased Nrf2 activity during ischemia in vivo, astrocytes and meningeal cells. Cultures were infected with an adenovirus reporter of Nrf2 transcriptional activity. Dopamine‐induced Nrf2 activity in both cell types by generating oxidative stressors, H2O2 and dopamine‐quinones. Nrf2 activation in meningeal cells was significantly higher than astrocytes. The effect of dopamine was blocked by antioxidants, and by over‐expression of either dominant‐negative Nrf2 or Keap1. Nrf2 induction was specific to oxidative stress caused by catecholaminergic neurotransmitters as epinephrine also induced Nrf2, but the monoamine serotonin had no significant effect. These in vitro results suggest Nrf2 activity in astrocytes and meningeal cells link the neurotoxic actions of dopamine to neuroprotective pathways that may potentially modulate ischemic injury and neurodegeneration.
Energy sources for glutamate neurotransmission in the retina: absence of the aspartate/glutamate carrier produces reliance on glycolysis in glia
Authors: Xu Y. , Ola M. S. , Berkich D. A. , Gardner T. W. , Barber A. J. , Palmieri F. , Hutson S. M. , LaNoue K. F. 
Published: January 2007

AbstractThe mitochondrial transporter, the aspartate/glutamate carrier (AGC), is a necessary component of the malate/aspartate cycle, which promotes the transfer into mitochondria of reducing equivalents generated in the cytosol during glycolysis. Without transfer of cytosolic reducing equivalents into mitochondria, neither glucose nor lactate can be completely oxidized. In the present study, immunohistochemistry was used to demonstrate the absence of AGC from retinal glia (Müller cells), but its presence in neurons and photoreceptor cells. To determine the influence of the absence of AGC on sources of ATP for glutamate neurotransmission, neurotransmission was estimated in both light‐ and dark‐adapted retinas by measuring flux through the glutamate/glutamine cycle and the effect of light on ATP‐generating reactions. Neurotransmission was 80% faster in the dark as expected, because photoreceptors become depolarized in the dark and this depolarization induces release of excitatory glutamate neurotransmitter. Oxidation of [U‐14C]glucose, [1‐14C]lactate, and [1‐14C]pyruvate in light‐ and dark‐adapted excised retinas was estimated by collecting 14CO2. Neither glucose nor lactate oxidation that require participation of the malate/aspartate shuttle increased in the dark, but pyruvate oxidation that does not require the malate/aspartate shuttle increased to 36% in the dark. Aerobic glycolysis was estimated by measuring the rate of lactate appearance. Glycolysis was 37% faster in the dark. It appears that in the retina, ATP consumed during glutamatergic neurotransmission is replenished by ATP generated glycolytically within the retinal Müller cells and that oxidation of glucose within the Müller cells does not occur or occurs only slowly.
Autoantibodies to alpha‐synuclein in inherited Parkinson’s disease
Authors: Papachroni Katerina K. , Ninkina Natalia , Papapanagiotou Angeliki , Hadjigeorgiou Georgios M. , Xiromerisiou Georgia , Papadimitriou Alexandros , Kalofoutis Anastasios , Buchman Vladimir L. 
Published: January 2007

AbstractNeurodegeneration in Parkinson’s disease (PD) is accompanied by a local immune reaction in the affected brain regions. It is well established that α‐synuclein is directly implicated in the pathogenesis of PD. Development of the disease is often associated with changes of expression and cellular compartmentalisation of this protein; moreover, its oligomers or protofibrils are often released to the CSF and plasma of patients. Aggregated α‐synuclein can trigger the activation of microglia; however, its capacity to induce production of specific autoantibodies (AAb) has not been assessed. In this study, we examined the presence of AAb against synuclein family members in the peripheral blood serum of PD patients and control individuals. Presence of AAb against β‐synuclein or γ‐synuclein showed no association with PD. Multi‐epitopic AAb against α‐synuclein were detected in 65% of all patients tested and their presence strongly correlated with an inherited mode of the disease but not with other disease‐related factors. The frequency of the presence of AAb in the studied group of patients with sporadic form of PD was not significantly different from the frequency in the control group but very high proportion (90%) of patients with familial form of the disease were positive for AAb against α‐synuclein. We hypothesise that these AAb could be involved in pathogenesis of the inherited form of PD.
Axonal involvement in the Wlds neuroprotective effect: analysis of pure motoneurons in a mouse model protected from motor neuron disease at a pre‐symptomatic age
Authors: Simonin Yannick , Perrin Florence E. , Kato Ann C. 
Published: January 2007

AbstractThe identification of the Wlds gene that delays axonal degeneration in several models of neurodegenerative disease provides an interesting tool to study mechanisms of axonal loss. We showed that crossing a mouse mutant with a motoneuron disease (pmn for progressive motor neuronopathy) with mice that express the Wlds gene delayed axonal loss, increased the life span, partially rescued axonal transport deficit and prolonged the survival of the motoneuron cell bodies. To determine factors involved in the neuroprotective effect of Wlds, we combined laser capture microdissection and microarray analysis to identify genes that are differentially regulated at a pre‐symptomatic age in motoneuron cell bodies in pmn/pmn,Wlds/Wlds mice as compared with pmn/pmn mice. Only 56 genes were de‐regulated; none of the ‘classical’ genes implicated in apoptosis were de‐regulated. Interestingly, a large proportion of these genes are related to axonal function and to retrograde and anterograde transport (i.e. members of the dynactin complex and kinesin family). These results were confirmed by real‐time PCR, in situ hybridization and at protein level in sciatic nerves. Thus, genes related to axonal function and in particular to axonal transport may be involved at an early stage in the neuroprotective property of the Wlds gene and confirm the importance of axonal involvement in this model of motor neuron disease.
Technical Note: A comparison of a novel direct ophthalmoscope, the OptyseTM, to conventional direct ophthalmoscopes
Authors: Harle Deacon E. , Davies Keri , Shah Rakhee , Hussain Syma , Cowling Susan , Panesar Tejinder K. , Bourton Jonathan , Evans Bruce J. W. 
Published: January 2007

AbstractDespite the current popularity of binocular indirect ophthalmoscopy, direct ophthalmoscopes are still commonly used by clinicians for fundus examination. They are considered to be expensive, however, and it has been suggested that this cost can prevent their use by healthcare professionals in developing countries. The OptyseTM Lens Free Ophthalmoscope is a novel direct ophthalmoscope, without a lens focus system, that allows for comparatively inexpensive manufacture and supply. We compared the clarity of view with the OptyseTM to that with standard direct ophthalmoscopes, over a sequential cohort of patients with a variety of refractive errors and ocular conditions. The grade of clarity of view with the OptyseTM Lens Free Ophthalmoscope was less than conventional ophthalmoscopes (Wilcoxon signed rank test, p < 0.0001). This grade of clarity of view was not associated with the ametropia of the ophthalmoscopic observation (Spearman r ≤ 0.03, p ≥ 0.28) but was with the presence of cataracts (χ2 test, p < 0.0001) with both the OptyseTM and the conventional ophthalmoscopes. Despite its limitations, the retinal view with OptyseTM was often within acceptable clinical limits suggesting that this relatively inexpensive ophthalmoscope may have a place when cost prohibits any other type of ophthalmoscope use.
Structure‐function studies for in vitro chemical inhibition of Fcγ receptor–mediated phagocytosis
Authors: Foo Alison H. , Fletcher Stephen P. , Langler Richard F. , Porter Charlotte H. , Branch Donald R. 
Published: January 2007

BACKGROUND: Previous studies [Transfusion 2005;45:384] showed that certain chemical compounds containing sulfur‐reactive groups can inhibit Fcγ receptor (FcγR)‐mediated phagocytosis in vitro. These studies, however, did not prove that only sulfur functionality–induced reactivity was efficacious. In an effort to develop a drug‐based approach for the future treatment of immune‐mediated cytopenias, these earlier findings have now been extended and this chemically induced interference with FcγR‐mediated phagocytosis of anti‐D‐coated red cells (RBCs) was examined to assess the optimal structural requirements for the inhibitory effect.STUDY DESIGN AND METHODS: Chemical compounds were purchased or synthesized and used for the assessment of which chemical moiety(‐ies) were required for successful inhibition of in vitro phagocytosis of anti‐D‐coated RBCs with a monocyte monolayer assay.RESULTS: Using compounds having similar structures but differences in reactive moieties, it was proved that the only chemical moiety that was required for inhibition of FcγR‐mediated phagocytosis in vitro was a disulfide bond. It is also shown, however, that a p‐nitrophenyl group provides significant enhancement to the inhibitory effect of disulfide‐containing compounds. Involvement of carbonyl and hydroxyl functional groups was also able to be ruled out.CONCLUSION: Our results confirm and extend previous studies that suggested that only those compounds that target free sulfhydryl groups on the monocyte‐macrophage are most effective at blocking phagocytosis of antibody‐coated RBCs in vitro. It is also shown that p‐nitrophenyl substituent groups have an enhancing effect on the efficacy of disulfide bond‐containing compounds. These findings should aid in the design of a drug‐based approach for the future treatment of immune cytopenias.
Vertical ridge augmentation with guided bone regeneration in association with dental implants: an experimental study in dogs
Authors: Simion Massimo , Dahlin Christer , Rocchietta Isabella , Stavropoulos Andreas , Sanchez Raquel , Karring Thorkild 
Published: January 2007

AbstractAim: To evaluate the effect of using guided bone regeneration (GBR) with a titanium‐reinforced e‐PTFE membrane in alveolar bone defects with titanium implants.Material and methods: Following extraction of three mandibular premolars and a molar on both sides of the jaw in three dogs, alveolar bone defects (depth: 5–7 mm) were produced. After 4 months, three implants were inserted into each defect to a depth of approximately 4 mm, so that their coronal portion was protruding about 5 mm. Four sides in the dogs were assigned to a test group and the remaining two sides to a control group. The 12 implants in the test group were covered with a reinforced e‐PTFE membrane. The space under the membrane was filled with peripheral venous blood from the animal, and the flaps were sutured over the membrane. The six control implants received no membrane before the suturing of the flaps to complete wound closure. The animals were sacrificed after 6 months, and non‐decalcified histological specimens of the implants and surrounding tissues were prepared.Results: Histologic and histomorphometric analyses revealed a significantly (Mann–Whitney test; P=0.08) larger amount of bone fill in the test group (mean=57.42%) than in the controls (mean=11.65%), and clinical evaluation of one test site showed that the implants were completely covered with tissue resembling bone. In most of the specimens, bone had grown in height close to, or in direct contact with the membrane. However, the new bone generally was not in direct contact with the implants. Regularly, a zone of dense connective tissue was interposed between the implants and the newly formed bone.Conclusion: The formation of even considerable amounts of bone following vertical ridge augmentation with GBR and implants was not accompanied by predictable osseointegration of the implants.
Oral health behaviour and its determinants amongst Iranian dental students1
Authors: Khami Mohammad R. , Virtanen Jorma I. , Jafarian Mohammad , Murtomaa Heikki 
Published: January 2007

Objectives: To study the oral health behaviour (OHB) of Iranian senior dental students in relation to their gender, background characteristics, knowledge of preventive care, and attitudes towards preventive dentistry.Materials and methods: Using a cluster random sampling approach, a questionnaire survey was conducted with 327 senior dental students in seven dental schools. The questionnaire covered age, gender, parents’ employment in dentistry, previous academic education in dental hygiene, oral self‐care, most recent dental check‐up, knowledge of preventive dentistry and attitudes towards it. Attending a dental check‐up by a dentist or a classmate within the last year was defined as preventive care use. Chi‐square test and logistic regression models were used for statistical analyses.Results: Women reported significantly higher frequencies of tooth brushing (P < 0.001), fluoridated toothpaste use (P = 0.001) and flossing (P < 0.001) compared with men. Respondents who had been previously educated as dental hygienists had lower frequencies of eating sugary snacks (P < 0.001) and paid more attention to preventive care (P = 0.03) than others. Those with more extensive knowledge of preventive care reported higher frequencies of using fluoridated toothpaste (P = 0.05). Reported frequencies of brushing were higher amongst those with more positive attitudes (P = 0.03). In logistic regression models, having at least one parent employed as a dentist was significantly associated with higher frequencies of eating sugary snacks (P = 0.047, OR = 0.3) and more frequent preventive care use (P = 0.048, OR = 2.9).Conclusion: Education and training in preventive measures should be effective enough to overcome background characteristics. There is room for improving the OHB of Iranian dental students.
The effect of a community dental service outreach programme on the confidence of undergraduate students to treat children: a pilot study
Authors: Hunter M. Lindsay , Oliver Richard , Lewis Rosamund 
Published: January 2007

Objective:  To examine the effect of a community dental service (CDS) outreach teaching programme on undergraduates’ confidence to undertake a range of paediatric dental procedures.Method:  Eighteen final year dental students completed a questionnaire prior to, and following participation in an outreach teaching programme. At each time point, the students were asked to identify how confident they felt to carry out a range of procedures commonly encountered in the treatment of children, employing a Likert scale modified to comprise six points where a rating of 1 represented ‘not at all confident’ and a rating of 6 ‘very confident’.Results:  The distribution of scores at each time point indicated that students were more confident to carry out each of the listed procedures following participation in the outreach teaching programme than they had been on completion of their paediatric dentistry sessions within the School of Dentistry. At the individual student level, 16 of the 18 students indicated that they were, overall, more confident following their placement than previously.Conclusions:  It can be concluded that the long‐established CDS outreach teaching programme run by the School of Dentistry, Wales College of Medicine in conjunction with the staff of Cardiff and Vale NHS Trust is a valuable adjunct to undergraduate teaching in paediatric dentistry.
Prevention‐oriented practice of Iranian senior dental students
Authors: Khami Mohammad R. , Virtanen Jorma I. , Jafarian Mohammad , Murtomaa Heikki 
Published: January 2007

Objectives:  To investigate self‐reported preventive practice of Iranian senior dental students in dental caries management.Subjects and methods:  To obtain an estimated sample size of 250 subjects, seven state dental schools were selected based on a stratified random sampling approach. All the senior dental students (n = 327) were asked to voluntarily fill in a self‐administered pre‐tested questionnaire during the spring term in 2005. In the questionnaire two hypothetical patient cases (a high‐risk and a low‐risk patient) were presented and the students were asked to express their conceptions on a five‐point Likert scale about including each of nine given alternatives in the patients’ treatment plans. The respondents’ self‐reported oral self‐care (OSC), preventive knowledge, attitude towards prevention and self‐perceived competency in giving preventive care were also assessed. Chi‐squared test and logistic regression model served for statistical analyses.Results:  A total of 270 students filled in the questionnaire (response rate = 82%). Acquiring high scores of preventive practice as assessed by patient cases was found to be more frequent among those reporting recommended OSC (P = 0.007) and those with higher attitude scores (P < 0.001). Also, those reporting being competent in giving preventive care had higher scores of preventive practice compared with the others (P = 0.02). In the regression model, recommended OSC (P = 0.05, OR = 1.9) and positive attitudes towards preventive dentistry (P = 0.001, OR = 3.3) showed significant association with acquiring highest scores of preventive practice.Conclusion:  To improve their preventive practice in the future, more emphasis should be placed on the dental students’ own oral health behaviour and attitudes related to it.
In Vitro Activity of Aurein 1.2 Alone and in Combination with Antibiotics against Gram-Positive Nosocomial Cocci
Authors: Giacometti Andrea , Cirioni Oscar , Riva Alessandra , Kamysz Wojciech , Silvestri Carmela , Nadolski Piotr , Della Vittoria Agnese , Łukasiak Jerzy , Scalise Giorgio 
Published: January 2007

ABSTRACT
This study was performed to evaluate the in vitro activity of the amphibian peptide aurein 1.2 and to investigate its interaction with six antibiotics against nosocomial gram-positive cocci. All isolates were inhibited at concentrations of 1 to 16 mg/liter. Synergy was demonstrated when aurein 1.2 was combined with clarithromycin and minocycline.
First Report of Plasmid-Mediated
qnrA1
in a Ciprofloxacin-Resistant
Escherichia coli
Strain in Latin America
Authors: Castanheira Mariana , Pereira Andrea S. , Nicoletti Adriana G. , Pignatari Antônio C. C. , Barth Afonso L. , Gales Ana C. 
Published: January 2007

ABSTRACT

Among 144 ciprofloxacin-resistant
Escherichia coli
isolated in Brazil, one (0.69%) QnrA1-producing isolate was detected. The
qnrA1
gene was associated with IS
CR1
. The QnrA1 determinant was carried on a 41-kb conjugative plasmid, which also carried a FOX-type cephalosporinase encoding gene and a class 1 integron with the
aadB
and
catB3
cassettes. This is the first report of a
qnrA
-carrying isolate in a Latin American country.