bluuebunny/crossref_metadata_2025 huggingface dataset:
Forearm Vascular Response to Nitric Oxide and Calcitonin Gene- Related Peptide: Comparison between Migraine Patients and Control Subjects
Authors: de Hoon JNJM , Smits P , Troost J , Struijker-Boudier HAJ , Van Bortel LMAB
Published: December 2005

The forearm vascular response to nitric oxide (NO) and calcitonin gene-related peptide (CGRP) was investigated in 10 migraine patients and 10 matched control subjects. Changes in forearm blood flow (FBF) during intrabrachial infusion of: (i) serotonin (releasing endogenous NO), (ii) sodium nitroprusside (SNP, exogenous NO-donor), and (iii) CGRP were measured using venous occlusion plethysmography. Flow-mediated dilation (FMD) of the brachial artery, a measure for the endogenous release of NO reactive to occlusion, was measured using ultrasound and expressed as percentage change vs. baseline diameter. FBF ratio (i.e. FBF in the infused over the control arm) at baseline (1.1 ± 0.1) did not differ between both populations. Serotonin, SNP and CGRP induced a dose-dependent increase ( P < 0.001) in FBF ratio in controls (to 2.8 ± 0.3, 6.7 ± 1.4 and 6.9 ± 1.2 at the highest dose, respectively) and migraineurs (2.5 ± 0.4, 5.6 ± 0.8 and 6.5 ± 1.3, respectively); these ratios did not differ between both groups. FMD was comparable in control subjects (5.8 ± 1%) and migraine patients (5.2 ± 1%). Based on the forearm vascular response to NO and CGRP, migraine patients do not display generalized changes in vascular function.
Stress-Induced Pain and Muscle Activity in Patients with Migraine and Tension-Type Headache
Authors: Leistad RB , Sand T , Westgaard RH , Nilsen KB , Stovner LJ
Published: December 2005

We recorded deep pain and surface electromyographic (EMG) responses to stress in 22 migraineurs during headache-free periods, 18 patients with tension-type headache (TTH), and 44 healthy controls. Sixty minutes of cognitive stress was followed by 30 min relaxation. EMG and pain (visual analogue scale) in the trapezius, neck (splenius), temporalis and frontalis areas were recorded. TTH patients had higher pain responses in temporalis and frontalis (with similar trends for trapezius and splenius) and more potentiation of pain during the test than controls. Migraine patients developed more pain in the splenius and temporalis than controls. Muscle pain responses were more regional (more pain in the neck and trapezius compared with the temporalis and frontalis) in migraine than in TTH patients. TTH patients had delayed pain recovery in all muscle regions compared with controls, while migraine patients had delayed pain recovery in a more restricted area (trapezius and temporalis). EMG responses were not different from controls in headache patients, and EMG responses did not correlate with pain responses. TTH patients had delayed EMG recovery in the trapezius compared with controls and migraine patients. These results support the concept that (probably central) sensitization of pain pathways and the motor system is important in TTH. Less pronounced and more regional (either peripheral or central) trigeminocervical sensitization seems to be important in migraine. Surface-detectable muscular activation does not seem to be causal for pain during cognitive stress either in migraine or in TTH.
The alternative splicing of tau exon 10 and its regulatory proteins CLK2 and TRA2‐BETA1 changes in sporadic Alzheimer's disease
Authors: Glatz Daniela C. , Rujescu Dan , Tang Yesheng , Berendt Frank J. , Hartmann Annette M. , Faltraco Frank , Rosenberg Carlyn , Hulette Christine , Jellinger Kurt , Hampel Harald , Riederer Peter , Möller Hans‐J. , Andreadis Athena , Henkel Kerstin , Stamm Stefan
Published: December 2005

Pathological inclusions containing fibrillar aggregates of hyperphosphorylated tau protein are a characteristic feature in tauopathies, which include Alzheimer's disease (AD). Tau is a microtubule‐associated protein whose transcript undergoes alternative splicing in the brain. Exon 10 encodes one of four microtubule‐binding repeats. Exon 10 inclusion gives rise to tau protein isoforms containing four microtubule‐binding repeats (4R) whereas exclusion leads to isoforms containing only three repeats (3R). The ratio between 3R and 4R isoforms is tightly controlled via alternative splicing in the human adult nervous system and distortion of this balance results in neurodegeneration. Previous studies showed that several splicing regulators, among them hTRA2‐beta1 and CLK2, regulate exon 10 alternative splicing. Like most splicing factors, htra2‐beta and clk2 pre‐mRNAs are regulated by alternative splicing. Here, we investigated whether human postmortem brain tissue of AD patients reveal differences in alternative splicing patterns of the tau, htra2‐beta, presenilin 2 and clk2 genes when compared with age‐matched controls. We found that the splicing patterns of all four genes are altered in affected brain areas of sporadic AD patients. In these affected areas, the amount of mRNAs of tau isoforms including exon 10, the htra2‐beta1 isoform and an inactive form of clk2 are significantly increased. These findings suggest that a misregulation of alternative splicing seems to contribute to sporadic AD.
Extracellular N‐acetylaspartate depletion in traumatic brain injury
Authors: Belli Antonio , Sen Jon , Petzold Axel , Russo Salvatore , Kitchen Neil , Smith Martin , Tavazzi Barbara , Vagnozzi Roberto , Signoretti Stefano , Amorini Angela Maria , Bellia Francesco , Lazzarino Giuseppe
Published: December 2005

N‐Acetylaspartate (NAA) is almost exclusively localized in neurons in the adult brain and is present in high concentration in the CNS. It can be measured by proton magnetic resonance spectroscopy and is seen as a marker of neuronal damage and death. NMR spectroscopy and animal models have shown NAA depletion to occur in various types of chronic and acute brain injury. We investigated 19 patients with traumatic brain injury (TBI). Microdialysis was utilized to recover NAA, lactate, pyruvate, glycerol and glutamate, at 12‐h intervals. These markers were correlated with survival and a 6‐month Glasgow Outcome Score. Eleven patients died and eight survived. A linear mixed model analysis showed a significant effect of outcome and of the interaction between time of injury and outcome on NAA levels (p = 0.009 and p = 0.004, respectively). Overall, extracellular NAA was 34% lower in non‐survivors. A significant non‐recoverable fall was observed in this group from day 4 onwards, with a concomitant rise in lactate–pyruvate ratio and glycerol. These results suggest that mitochondrial dysfunction is a significant contributor to poor outcome following TBI and propose extracellular NAA as a potential marker for monitoring interventions aimed at preserving mitochondrial function.
Anomalous response to potassium in vascular smooth muscle cells of human saphenous vein
Authors: Bieger D. , Mong K. , Tabrizchi R.
Published: December 2005

1 We have examined the relationship between the resting membrane potential (Em) and the concentration of the external ions, K+, Cl− and Ca2+, as well as the effects of K+ on active force generation in human saphenous veins.

2 As measured with sharp glass microelectrodes, the Em of vascular muscle cells was −76.0 ± 7.0 mV (mean ± SD; n = 328). Raising the concentration of external potassium ([K+]e) from 4.2 to 20, 40, 80, 120 or 150 mm produced an incremental depolarization, revealing a maximal slope factor of 15 mV per 10‐fold increase.

3 Oubain (1.0 μm) did not have any effect on Em (−79.0 ± 8.0 mV; n = 80). Replacement of external Cl− with propionate resulted in significant (P < 0.05) depolarization (Em: −65.5 ± 7.5 mV; n = 40). In Cl−‐free buffer containing 80 mm K+, Em depolarized to −52.0 ± 6.7 mV (n = 45) compared with −64.7 ± 6.5 mV (n = 55) (P < 0.05) measured in buffer containing 80 mm [K+]e and Cl− 138.7 mm. Removal of Ca2+ did not significantly modify the depolarizing response to K+ 80 mm: Em, −68.2 ± 4.9 mV (n = 42) vs.−64.7 ± 6.5 mV (n = 55) in the presence of Ca2+.

4 Despite their small size, changes in Em correlated closely with force generation in buffer containing high K+, approximately 3.62 mN force being generated per mV of change in Em.

5 These data demonstrate that, in human saphenous smooth muscle cells, (i) the magnitude of depolarization induced by raising [K+]e deviates considerably from the theoretical values predicted by the Goldman–Hodgkin–Katz equations, (ii) Cl− appears to contribute to the maintenance of Em, and (iii) electromechanical coupling has a low threshold.
Relaxant responses to calcium channel antagonists and potassium channel opener in human saphenous vein
Authors: Ford C. , Bieger D. , Mong K. , Tabrizchi R.
Published: December 2005

1 As shown in a parallel study the magnitude of depolarization induced in human saphenous vein by raising external potassium ([K+]e) falls markedly below the theoretical values predicted by the Goldman–Hodgkin–Katz equations. This anomaly prompted us to re‐examine the relaxant actions of L‐type (nifedipine) and T‐type (mibefradil) Ca2+ channel antagonists, and relaxant and electrophysiological effects of the K+ channel opener, pinacidil, on saphenous veins contracted by the elevation of [K+]e.

2 Nifedipine produced concentration–dependent relaxations in tissues contracted at various high [K+]e. In tissues contracted with 20 mm [K+]e, the pIC50 for nifedipine was significantly (8.20 ± 0.05; n = 6; mean ± SEM; P < 0.05) greater than in tissues contracted with ≥40 mm [K+]e.

3 Tissues contracted with 20 mm [K+]e also relaxed in response to mibefradil (pIC50 = 6.1 ± 0.14) and pinacidil (pIC50 = 6.45 ± 0.08), the latter being almost completely reversed (93.4 ± 9.9%) by addition of glibenclamide (10 μm).

4 The resting Em of smooth muscle cells of saphenous vein was −77.0 ± 0.7 mV (n = 52), and 20 mm [K+]e produced a modest but significant depolarization to −73.0 ± 0.7 mV (n = 52). Incubation with pinacidil plus 20 mm [K+]e resulted in a significant hyperpolarization of the Em to −82 ± 0.6 mV (n = 52).

5 Nω‐nitro‐l‐arginine methyl ester did not impede the relaxant responses of nifedipine, mibefradil or pinacidil.

6 In conclusion, the relaxant effects of nifedipine and pinacidil (i) occurred at an Em distinctly below the presumed threshold for the opening of the classic (CaV1.3α1) L‐type Ca2+ channels, and (ii) did not depend on generation of nitric oxide.
Captopril therapy decreases both expression and function of α1D‐adrenoceptors in pre‐ hypertensive rat aorta
Authors: Godínez‐Hernández D. , Gallardo‐Ortíz I. A. , López‐Sánchez P. , Villalobos‐Molina R.
Published: December 2005

1 The effects of captopril onα1‐adrenoceptor mRNA and protein and phenylephrine‐induced contraction was assessed in aorta of pre‐hypertensive spontaneously hypertensive rats.

2 Four‐week‐old SHR and WKY rats were treated with captopril [an angiotensin‐converting enzyme (ACE) inhibitor] 3 mg kg−1 day−1for 1 week.

3 pA2values for BMY 7378, anα1D‐adrenoceptor antagonist, were 8.63–9.20 among the different groups. Schild slopes were close to unity suggesting that contraction was produced primarily byα1D‐adrenoceptor stimulation and was not changed with therapy.

4 α1D‐Adrenoceptor mRNA and protein values were higher in pre‐hypertensive SHR than in WKY, whereasα1A‐adrenoceptor mRNA was higher in WKY andα1B‐adrenoceptors were similar in both strains, and protein was not significantly different forα1A‐ andα1B‐subtypes.

5 Captopril decreased maximal contraction in SHR, without having effect in WKY rats, whileα1D‐adrenoceptor mRNA was decreased in both rat strains butα1D‐adrenoceptor protein was significantly decreased only in SHR, and increasedα1A‐mRNA in SHR, no effect of captopril treatment was observed onα1B‐adrenoceptor mRNA and protein nor onα1A‐adrenoceptor protein.

6 These data suggest that ACE inhibition by captopril influences both expression and function ofα1D‐adrenoceptors in aorta of pre‐hypertensive rats, probably avoidingα1D‐subtype expression by blockade of angiotensin II synthesis.
Right ventricular myocardial isovolumic relaxation time and pulmonary pressure
Authors: Lindqvist Per , Waldenström Anders , Wikström Gerhard , Kazzam Elsadig
Published: December 2005

Aims:  Non‐invasive assessment of pulmonary artery systolic pressure (PASP) has several limitations. As previously described by Burstin, the right ventricular (RV) isovolumic relaxation time (IVRt) is sensitive to changes in PASP. We therefore compared RV myocardial IVRt, derived by Doppler tissue imaging (DTI), with simultaneously measured invasive PASP.

Methods and results:  Twenty‐six consecutive patients (18 males, mean age 52 ± 12 years, range 23–75) underwent a simultaneous Doppler echocardiography, including DTI, and cardiac catheterization examination for measurement of PASP and right atrial mean pressures. IVRt was measured using the myocardial velocities by pulsed DTI at both basal and mid cavity segments of the RV free wall. As diastolic time intervals are influenced by heart rate IVRt was corrected for heart rate (IVRt/RR%). A significant correlation was found between PASP and regional IVRt/RR% at both the basal (r = 0·42, P<0·05) and mid cavity segment (r = 0·71, P<0·001). Furthermore, when only patients with normal right atrial pressures (<7 mmHg) were taken into account, the correlation coefficient improved at both basal and mid cavity segments (r = 0·74, P<0·05 and r = 0·83, P<0·01).

Conclusion:  Pulsed Doppler‐derived IVRt correlates well with PASP. The use of pulsed DTI for measurement of IVRt is simple, reproducible and easy to obtain. We propose this method as an additional non‐invasive tool in the assessment of PASP.
Blood pressure and cerebral oxygenation responses to skeletal muscle tension: a comparison of two physical maneuvers to prevent vasovagal reactions
Authors: France C. R. , France J. L. , Patterson S. M.
Published: December 2005

Aim:  The present study compared blood pressure, heart rate, and cerebral oxygenation responses to two manipulations used to prevent vasovagal reaction – skeletal muscle tensing alone and skeletal muscle tensing with leg crossing.

Methods and Results:  Using a repeated measures within‐subjects design, healthy young adults engaged in a brief laboratory protocol that included an initial 3 min resting baseline, 3 min of muscle tensing (or no‐tensing control), and a 1 min orthostatic challenge. This sequence was repeated three times for each participant to allow for a direct comparison of physiological responses to two different muscle‐tensing manipulations as compared to the no‐tensing control condition. Results indicated that, relative to the no‐tensing, both muscle tensing manipulations elicited significant increases in systolic blood pressure (8·7 ± 1·1 mmHg), diastolic blood pressure (4·9 ± 0·6 mmHg), and heart rate (10·9 ± 0·9 bpm), while a significant increase in cerebral oxygenation was only observed in response to muscle tensing with legs crossed (0·8 ± 0·2%). Blood pressure and heart rate responses to orthostatic challenge did not differ between the two tensing manipulations, although muscle tensing with legs crossed was followed by a more rapid recovery of cerebral oxygenation levels.

Conclusion:  These findings suggest that muscle tensing elicits physiological adaptations that may help reduce the risk of vasovagal reactions; however, the combination of lower body tension with the legs crossed is likely to be most effective as it was uniquely associated with significant increases in the flow of oxygenated blood to the brain.
Effects of local arteriosclerosis on carotid baroreflex sensitivity and on heart rate and arterial pressure variability in humans
Authors: Eiken Ola , Nowak Jacek , Jogestrand Tomas , Mekjavic Igor B.
Published: December 2005

The study examined whether the alterations in heart rate variability (HRV) and baroreflex sensitivity (BRS) observed in patients with coronary artery disease can also be discerned in otherwise healthy subjects with mild‐to‐moderate arteriosclerosis in the carotid artery bifurcation. Based on the results of carotid duplex ultrasonography, subjects were designated as either having no arteriosclerotic lesions (n = 18), unilateral (n = 19) or bilateral lesions (n = 18) in the bifurcation. Electrocardiograms were recorded and simultaneous and continuous records of arterial pressure were obtained. Resting HRV was determined by calculating the spectral power density in three frequency bands: 0–0·05 Hz [very low frequency (VLF) band], 0·05–0·15 [low frequency (LF) band] and 0·15–2 Hz (high frequency band), whereas the arterial pressure variability (APV) was determined from spectral power density of the VLF and LF bands. Carotid BRS was evaluated by measuring R‐R intervals during application of pulse‐synchronous graded pressures (40 to −65 mmHg) in a neck‐chamber device. Analysis of variance revealed no effect of mild‐to‐moderate carotid arteriosclerosis on the spectral components of HRV and APV or on BRS. It thus appears that mild‐to‐moderate asymptomatic carotid arteriosclerosis does not affect carotid BRS, APV or HRV at rest.
Real‐time perfusion adenosine stress echocardiography versus myocardial perfusion adenosine scintigraphy for the detection of myocardial ischaemia in patients with stable coronary artery disease
Authors: Gudmundsson Petri , Winter R. , Dencker M. , Kitlinski M. , Thorsson O. , Ljunggren L. , Willenheimer R.
Published: December 2005

Background:  Real‐time perfusion (RTP) contrast echocardiography using low mechanical index power modulation technique allows for simultaneous myocardial perfusion and wall motion analysis. RTP‐adenosine stress echocardiography (ASE) could be an alternative to dobutamine‐atropine stress echocardiography; more tolerable for the patients and possibly similarly accurate. We aimed to evaluate RTP‐ASE for the detection of myocardial ischaemia, compared to 99mTc‐sestamibi single‐photon emission computed tomography (SPECT).

Methods:  Patients with suspected coronary artery disease, admitted to SPECT evaluation, were prospectively invited to participate. Patients underwent RTP imaging (SONOS 5500) using infusion of Sonovue® (Bracco, Milano, Italy) before and during ASE. Two separate readers performed off‐line analysis of myocardial perfusion and wall motion by RTP‐ASE. A perfusion defect was the principal marker of ischaemia. Wall motion assessment was used to evaluate ischaemia in segments with perfusion artefacts. Each segment was attributed to one of the three main coronary vessel areas of interest: the left anterior descending (LAD); the left circumflex (LCx) and the right posterior descending (RPD). Normal SPECT at stress was judged normal at rest.

Results:  In 33 patients, 99 coronary territories were analysed by SPECT and RTP‐ASE. SPECT showed evidence of ischaemia in 9 of 33 patients. For the detection of ischaemia, the overall level of agreement between RTP‐ASE and SPECT was 92% in all segments. The level of agreement was 88% in LAD, 97% in LCx and 91% in RPD segments.

Conclusion:  Real‐time perfusion‐adenosine stress echocardiography using power modulation could be an accurate and feasible tool for evaluation of ischaemia in patients with suspected coronary artery disease. The results from this study need confirmation by a study of a larger patient sample.
Acoustic effects of positive end‐expiratory pressure on normal lung sounds in mechanically ventilated pigs
Authors: Vena Antonio , Perchiazzi Gaetano , Giuliani Rocco , Fiore Tommaso , Hedenstierna Göran
Published: December 2005

Computerized lung sounds analysis offers a new technique to monitor regional ventilation during spontaneous breathing. The purpose of the present study was to assess the acoustic behaviour of the respiratory system in healthy pigs during mechanical ventilation when a positive end‐expiratory pressure (PEEP) is applied. Lung sounds were recorded during mechanical ventilation and different PEEP levels of 0, 5, 10, 15 and 20 cmH2O were applied. The increase in end‐expiratory lung volume (EELV) related to the PEEP application was also measured and the correlation between changes in EELV (ΔEELV) and sound amplitude (ΔA) was examined. The amplitude of normal lung sounds was reduced by application of PEEP ≥10 cmH2O (P<0·05). The increase in PEEP from 0 to 20 cmH2O reduced the acoustic energy of lung sounds recorded at ZEEP by 0·3 dB (PEEP 5), 2 dB (PEEP 10), 5 dB (PEEP 15) and 7 dB (PEEP 20), which corresponds to 1%, 6%, 14% and 21% in acoustic attenuation, respectively. The variations in ΔA correlated with changes in lung volume (P<0·05) and with changes in compliance of the respiratory system (P<0·05), but were not correlated with changes of the resistance of respiratory system. The frequency analysis showed a downward shifting of the spectra at frequencies between 150 and 600 Hz for PEEP levels ≥10 cmH2O and frequencies between 75 and 600 Hz for PEEP levels ≥15 cmH2O. The application of increasing levels of PEEP reduced the amplitude and changed the spectral characteristics of normal lung sounds.
Linear and non‐linear heart rate variability measures in chronic and acute phase of anorexia nervosa
Authors: Platisa Mirjana M. , Nestorovic Zorica , Damjanovic Svetozar , Gal Vera
Published: December 2005

Previous results on heart rate variability (HRV) analysis in anorexia nervosa (AN) include some apparently conflicting data. In order to find out the reason for different results and to improve understanding of autonomic control in AN we compare HRV in acute and chronic AN. Spectral powers, fractal scaling exponent and sample entropy were computed from 24 h RR series derived from Holter ECG recordings in 17 anorexic patients, nine chronic and eight healthy women. We found that all linear and non‐linear HRV measures change in different direction in acute and chronic AN. Acute AN is characterized by decreased HR and increased HRV. In chronic AN, HR is increased, HRV reduced and the difference between awake and sleeping values is high. HRV measures are associated with body mass index only in chronic AN. As HRV measures are significantly different between acute and chronic AN, we propose that HRV analysis might provide additional data in clinical practice.
The Political Economy of Gender: Explaining Cross‐National Variation in the Gender Division of Labor and the Gender Voting Gap
Authors: Iversen Torben , Rosenbluth Frances
Published: December 2005

Mainstream political economy has tended to treat the family as a unit when examining the distributional consequences of labor market institutions and of public policy. In a world with high divorce rates, we argue that this simplification is more likely to obscure than to instruct. We find that labor market opportunities for women, which vary systematically with the position of countries in the international division of labor and with the structure of the welfare state, affect women's bargaining power within the family and as a result, can explain much of the cross country variation in the gender division of labor as well as the gender gap in political preferences.
Cultivating Character: John Stuart Mill and the Subject of Rights
Authors: Zivi Karen
Published: December 2005

The antidemocratic tendencies of rights appear to be numerous. As trumps, rights are denounced for shutting down political debate and undermining the common good. As disciplinary, rights are attacked for reinforcing a politics of exclusion. I argue that an appreciation of the democratic potential of rights requires conceiving of them as political claims, as claims that represent a perspective that we seek to persuade others to adopt and through which we can create and contest community and identity. I cull a political conception of rights from the work of John Stuart Mill by rethinking the meaning of and connection between his ontological commitments and his politics. Paying careful attention to his notion of “character” and its cultivation, I argue that Mill embraces a conception of the socially constituted subject who is both disciplined and enabled by rights.
Cooptation or Transformation? Local Policy Networks and Federal Regulatory Enforcement
Authors: Scholz John T. , Wang Cheng‐Lung
Published: December 2005

Local policy networks can aid federal agencies, but they can also coopt federal resources for unintended purposes. Our empirical study finds that effective local networks increase both enforcement and compliance rates for the Clean Water Act. We discuss the circumstances under which effective networks can transform political culture, enhancing enforcement and compliance even in conservative areas generally opposed to regulation. The modified detection‐controlled estimation procedure enables us to utilize official enforcement records from 1994 to 2000 to study both enforcement and compliance.
Constitutional Review and the Selective Promotion of Case Results
Authors: Staton Jeffrey K.
Published: December 2005

A significant majority of the world's constitutional courts publicize their decisions through direct contact with the national media. This interest in public information is puzzling in so far as constitutional judges are not directly accountable to voters. I argue that the promotion of case results is consistent with a theory of judicial behavior in which public support for courts can undermine incentives for insincere decision making. In this article, I develop a simple game theory model that identifies how case promotion is linked to judicial choice. Results of a simultaneous equations model estimating the Mexican Supreme Court's merits decisions and its choices to publicize those decisions by issuing press releases to national media outlets support an account of constitutional review in which judges believe they can influence their authority through case promotion.
Earthquakes and Aftershocks: Race, Direct Democracy, and Partisan Change
Authors: Bowler Shaun , Nicholson Stephen P. , Segura Gary M.
Published: December 2005

Although dramatic partisan change among the electorate is infrequent, the issue agendas of parties may produce large shifts. A major cause of such change is the politics of race. In a political environment charged with racially oriented issues, racial groups often align themselves with different parties (as witnessed most recently in the American South). Yet, if racial appeals violate norms of equality, these appeals may rebound on the party using them. Consequently, members of the (white) racial majority and racially targeted minority may both move away from the offending party. Using data from the California Field Poll, we find that racially charged ballot propositions sponsored by the Republican party during the 1990s in California reversed the trend among Latinos and Anglos toward identifying as Republican, ceteris paribus, by shifting party attachments toward the Democratic party. Our results raise serious questions about the long‐term efficacy of racially divisive strategies for electoral gain.
Selection Bias and Continuous‐Time Duration Models: Consequences and a Proposed Solution
Authors: Boehmke Frederick J. , Morey Daniel S. , Shannon Megan
Published: December 2005

This article analyzes the consequences of nonrandom sample selection for continuous‐time duration analyses and develops a new estimator to correct for it when necessary. We conduct a series of Monte Carlo analyses that estimate common duration models as well as our proposed duration model with selection. These simulations show that ignoring sample selection issues can lead to biased parameter estimates, including the appearance of (nonexistent) duration dependence. In addition, our proposed estimator is found to be superior in root mean‐square error terms when nontrivial amounts of selection are present. Finally, we provide an empirical application of our method by studying whether self‐selectivity is a problem for studies of leaders' survival during and following militarized conflicts.
Monotone Comparative Statics for Models of Politics
Authors: Ashworth Scott , Bueno de Mesquita Ethan
Published: December 2005

We elucidate a powerful yet simple method for deriving comparative statics conclusions for a wide variety of models: Monotone Comparative Statics (Milgrom and Shannon 1994). Monotone comparative static methods allow researchers to extract robust, substantive empirical implications from formal models that can be tested using ordinal data and simple nonparametric tests. When these methods apply, they can replace a diverse range of more technically difficult mathematics (facilitating richer, more realistic models), assumptions that are hard to understand or justify substantively (highlighting the political intuitions underlying a model's results), and a complicated set of methods for extracting implications from models. We present an accessible introduction to the central monotone comparative statics results and a series of practical tools for using these techniques in applied models (with reference to original sources, when relevant). Throughout we demonstrate the techniques with examples drawn from political science.
Measuring Legislative Accomplishment, 1877–1994
Authors: Clinton Joshua D. , Lapinski John S.
Published: December 2005

Understanding the dynamics of lawmaking in the United States is at the center of the study of American politics. A fundamental obstacle to progress in this pursuit is the lack of measures of policy output, especially for the period prior to 1946. The lack of direct legislative accomplishment measures makes it difficult to assess the performance of our political system. We provide a new measure of legislative significance and accomplishment. Specifically, we demonstrate how item‐response theory can be combined with a new dataset that contains every public statute enacted between 1877 and 1994 to estimate “legislative importance” across time. Although the resulting estimates and associated standard errors provide new opportunities for scholars interested in analyzing U.S. policymaking since 1877, the methodology we present is not restricted to Congress, the United States, or lawmaking.
Mechanism and Kinetics of Aluminum Nitride Powder Degradation in Moist Air
Authors: Li Jinwang , Nakamura Masaru , Shirai Takashi , Matsumaru Koji , Ishizaki Chanel , Ishizaki Kozo
Published: December 2005

Aluminum nitride (AlN) powders manufactured via three major commercial processes, namely, chemical vapor deposition from triethyl aluminum, carbothermal reduction and nitridation of alumina, and direct nitridation of aluminum, were exposed to moist air at room temperature to investigate the degradation mechanism and kinetics. In the degradation, the powders were initially hydrolyzed to amorphous aluminum oxyhydroxide, which subsequently transformed into mixtures of crystallized aluminum trihydroxide (Al(OH)3) polymorphs, i.e., bayerite, nordstrandite, and gibbsite, forming agglomerates around the unreacted AlN. The data were fitted by using the unreacted‐core model. Three stages were found in the degradation: the stage of an induction period at the beginning, followed by a stage of fast hydrolysis with the chemical reaction being rate controlling, and finally, with gradual closing of pores in the structure of Al(OH)3 around AlN, changing to a stage of slow hydrolysis that was controlled by mass diffusion through Al(OH)3. The existence of an induction period was attributed to slow hydrolysis of the surface oxide/oxyhydroxide layer. The powder produced by the carbothermal process showed the longest induction period, which was attributed to its surface structure being different from other powders.
Novel Anion Exchange Method for Exact Antimony Doping Control of Stannic Oxide Nanocrystal Powder
Authors: Zhang Xuejun , Liang Hongbo , Gan Fuxing
Published: December 2005

There are major problems associated with the preparation of nanometer‐sized antimony‐doped stannic oxide using the current sol–gel processes, such as difficulties in removing chlorine, in accurate doping of antimony, and in the repeatability of doping. This paper presents a novel solution method of doping, which involves a precipitation–condensation process with non‐aqueous ion exchange for removal of chlorine. This involved hydrolysis of SnCl4·5H2O and SbCl3 in an ethanol–ammonia anion‐exchange resin mixture at pH=6–8. The removal of chlorine ion and the hydrolysis are conducted at the same time. The short duration of hydrolysis prevents the formation of high condensates. The use of ion‐exchange resin saves a great deal of solvent and allows all the hydrolysis products to be recovered by distillation. This ensured that the doping is exact. The determination of antimony within the dry hydrolysate on an atomic absorption spectrometer confirmed the doping accuracy and the repeatability of the method. The proportion of Sb to Sn was found to be between 0.0528 and 0.0550 molar fraction at the optimum conductivity of the nanocrystalline SnO2 doped with Sb. TEM pictures and XRD patterns showed that nanocrystallites fired from the powder were small and had a narrow size range of 10±5 nm at 650°C.
Ophthalmological findings in children born after intracytoplasmic sperm injection
Authors: Wikstrand Margareta Hök , Strömland Kerstin , Flodin Sara , Bergh Christina , Wennerholm Ulla‐Britt , Hellström Ann
Published: December 2005

Purpose:  To investigate visual function and ocular morphology in children born after intracytoplasmic sperm injection (ICSI) and compare them with visual function and ocular morphology in matched children born after spontaneous conception.

Methods:  A total of 137 children born after ICSI and 159 control children were examined at the age of 5 years in a blinded study. The two groups were matched for age, gender and maternal age. The children underwent a detailed ophthalmological investigation by an ophthalmologist and an orthoptist.

Results:  A total of 90.4% of the ICSI children had a visual acuity (VA) in the better eye of ≥ 0.8, compared with 93.7% of the controls (NS). No significant differences were found between ICSI children and controls with regard to hyperopia, myopia, astigmatism, heterotropia, stereoscopic vision and convergence. One child with Goldenhar syndrome and one with Marcus Gunn syndrome were observed in the ICSI group. One child in the ICSI group was treated for retinopathy of prematurity.

Conclusion:  In this limited study group, no significant differences in visual function and/or ocular morphology were found between children born after ICSI and matched control children at the age of 5 years.
Visual prognosis after panretinal photocoagulation for proliferative diabetic retinopathy
Authors: Bek Toke , Erlandsen Mogens
Published: December 2005

Introduction: Proliferative diabetic retinopathy is treated with panretinal photocoagulation, which improves the visual prognosis in this complication considerably. The visual acuity (VA) and grade of retinopathy before treatment are known indicators of the visual prognosis after treatment, but the prognostic value of other clinical background and treatment parameters is unknown.

Methods: The study reports predictors for visual outcome identified among retrospective clinical background data and treatment parameters from 4422 panretinal photocoagulation sessions for proliferative diabetic retinopathy in 1013 eyes of 601 patients performed at the Department of Ophthalmology, Århus University Hospital between 1985 and 2002.

Results: High pretreatment VA and low age were strong positive predictors of post‐treatment VA (p < 0.0001). However, diabetes type, diabetes duration and calendar year of treatment showed no influence on post‐treatment VA (p = 0.7829, 0.1782, and 0.3747, respectively). The visual prognosis was inversely related to the number of treatment sessions (p = 0.0259) and the number of vitrectomies (OR = 2.66 [1.24; 5.69], p = 0.0117, for more than two operations). However, the visual prognosis was unrelated to any of the other parameters studied.

Conclusions: Pretreatment VA, age and the number of panretinal photocoagulation treatment sessions and vitrectomies necessary to halt the disease are indicators of the visual prognosis after panretinal laser photocoagulation for proliferative diabetic retinopathy.
Polytetrafluoroethylene (Goretex®) for muscle elongation in the surgical treatment of strabismus with restricted motility
Authors: Langmann Andrea , Lindner Susanne , Wackernagel Werner , Koch Martina , Hörantner Robert
Published: December 2005

Purpose:  Repeated strabismus surgery as well as eye muscle fibrosis in various forms of strabismus, can be followed by restriction of the motility of the eye. Tendon elongation may be necessary if further improvement of the deviation and duction of the eye muscle is to be achieved. We used polytetrafluoroethylene (Goretex®) and looked at its user comfort, compatibility and dose–rate relationship.

Method:  Three patients with consecutive exotropia after repeated operations for congenital esotropia, two patients with VI nerve palsy and residual head turn after combined convergence operation and one child with congenital fibrosis syndrome underwent muscle tendon elongation with Goretex® (7–15 mm) of either the medial or the lateral rectus muscle, which had already been resected and/or recessed in former surgeries. Forced duction under general anaesthesia was restricted in all patients.

Results:  The correction of the deviation in primary position (deviation at distance + 3 ° to − 4 ° and at near − 1 ° to − 8 °) and in side gaze was satisfactory and motility was clearly improved. There were no postoperative complications (infection, shrinkage, scarring) and the postoperative results in terms of the angle of deviation and the improvement in motility remained stable for 1–6 years.

Conclusion:  Polytetrafluoroethylene (Goretex®) is a good material with which to resolve complicated cases of strabismus in which muscle tendon elongation for bulbus restriction is necessary.
Predictive value of exfoliative cytology in pigmented conjunctival lesions
Authors: Keijser Sander , Van Luijk Chantal M. , Missotten Guy S. , Veselic‐Charvat Maud , De Wolff‐Rouendaal Didi , De Keizer Rob J. W.
Published: December 2005

Purpose:  Pigmented lesions of the conjunctiva are often difficult to classify clinically. Exfoliative cytology may be helpful, but reliable data regarding the sensitivity and specificity of this test are currently lacking. We determined the value of exfoliative cytology with regard to pigmented conjunctival lesions.

Methods:  A total of 294 smears from 182 patients were screened for malignancy within 6 months of exfoliative cytology. Smears were classified according to the following categories: grade 0 = insufficient material for diagnosis; grade 1 = normal conjunctival cells; grade 2 = melanocytes with mild atypia; grade 3 = melanocytes with moderate atypia, and grade 4 = melanocytes with severe atypia.

Results:  The sensitivity, specificity, positive predictive value and negative predictive value of exfoliative cytology were 85%, 78%, 59% and 93%, respectively.

Conclusion:  Exfoliative cytology is a fast, easy and non‐invasive technique that may be used in the evaluation of patients with a pigmented conjunctival lesion.
The effects of limnological features on fish assemblages of 14 Spanish reservoirs
Authors: Carol J. , Benejam L. , Alcaraz C. , Vila‐Gispert A. , Zamora L. , Navarro E. , Armengol J. , García‐Berthou E.
Published: December 2005

Abstract –  The relationship of water quality and fish assemblages has been poorly documented in European reservoirs, despite being important for water management and ecological monitoring. We sampled the fish assemblages of 14 Spanish reservoirs by boat electrofishing in the littoral and multi‐mesh gillnets in the limnetic zone. Simultaneously, we assembled eight physical descriptors and we measured 20 water quality features of the reservoirs. Multivariate analysis (ordination methods and generalised additive models) showed that altitude and trophic state (indicated by chlorophyll or nutrient concentrations) independently explained most of the variation of fish assemblages in these reservoirs. The most eutrophic reservoirs were dominated by common carp (Cyprinus carpio) whereas oligotrophic reservoirs presented other fish species intolerant to pollution rather native (such as brown trout, Salmo trutta). The absolute and relative abundance of common carp was strongly related to the trophic state of the reservoir and 40% of its variation was explained by total phosphorous concentration. Despite clear changes in species composition, there was no significant effect of water quality on overall fish richness or Shannon's diversity, suggesting that for such low richness assemblages species composition is a better indicator of cultural eutrophication of reservoirs than fish diversity.
Impact of wearing an intra‐oral lubricating device on oral health in dry mouth patients
Authors: Frost PM , Shirlaw PJ , Challacombe SJ , Fernandes‐Naglik L , Walter JD , Ide M
Published: December 2005

Objective:  To establish whether an intra‐oral lubricating device for dry mouth alters the oral environment.

Design:  A single‐blind randomized cross‐over study.

Method:  Twenty‐nine dentate subjects from the Sjogren's syndrome clinic attended on five occasions at 4‐week intervals. They were randomized, having the device fitted on either the second or the fourth visit for the experimental period, whilst using their preferred method of lubrication throughout the rest of the study. The preferred methods of lubrication were either water (group 1, n = 10) or saliva substitute (group 2, n = 9) or sugar‐free chewing gum (group 3, n = 10). At each visit microbiological, unstimulated and stimulated saliva samples were collected. Dry mouth score, speech test and periodontal indices were recorded.

Results:  The water lubrication group (1) had a resting salivary flow greater than lubrication groups (2 and 3) by post‐ANOVA contrasts (P < 0.001). The postdevice data also demonstrated a salivary flow greater than lubrication group (3) by post‐ANOVA contrasts (P < 0.05). The epithelial cell count using the Spearman correlation was high, possibly reflecting increased viscosity of the saliva (P = 0.044). The speech test indicated that the experimental subjects had difficulty in speaking (P = 0.001). This was slightly easier postdevice wear. Streptococcus mutans (P = 0.009) and Lactobacillus (P = 0.058) increased in the saliva after wearing the device. Salivary flow rate, Candida albicans, oral dryness, speaking and periodontal indices were unchanged.

Conclusions:  The oral environment was altered by wearing a lubricating device with an increase in the numbers of Strep. mutans and Lactobacillus. Clinical dryness and speech test correlated with the mean whole salivary flow suggesting a screening method for xerostomia.
Manifestations of the tongue in Neurofibromatosis type 1
Authors: Bongiorno MR , Pistone G , Aricò M
Published: December 2005

Objective:  The aim of this study is to analyse alterations of the tongue and the correlation between these lesions and different types of tumor.

Subjects and methods:  A total of 258 cases (131 females, 127 males) of neurofibromatosis type 1 were screened between 1994 and 2004 in our Dermatology Department. All patients included in this study have NF1, as defined by the NIH Consensus Conference. Three cases of neurofibromas of the tongue in patients with neurofibromatosis type were reported.

Results:  Our patients showed nodular lesions on the tongue, related to neurofibromas in two patients and plexiform neurofibroma in one patient, respectively. Clinical and hystopatological findings were useful in distinguishing between neurofibromas and other soft tissue tumors. An increased prevalence of malignancy has been documented in patients affected by neurofibromatosis type 1. Changes in the size of a pre‐existing mass, compression, or infiltration of the adjacent structures indicate malignant degeneration. Histological and clinical evaluation should be performed in order to choose the most appropriate treatment strategy for these patients.

Conclusion:  The oral manifestations of NF are well‐documented but may not be at the forefront of the clinician's mind in the differential diagnosis of intra‐oral swellings.
A tyrosinase with an abnormally high tyrosine hydroxylase/dopa oxidase ratio
Authors: Hernández‐Romero Diana , Sanchez‐Amat Antonio , Solano Francisco
Published: December 2005

The sequencing of the genome of Ralstonia solanacearum[Salanoubat M, Genin S, Artiguenave F, et al. (2002) Nature415, 497–502] revealed several genes that putatively code for polyphenol oxidases (PPOs). This soil‐borne pathogenic bacterium withers a wide range of plants. We detected the expression of two PPO genes (accession numbers NP_518458 and NP_519622) with high similarity to tyrosinases, both containing the six conserved histidines required to bind the pair of type‐3 copper ions at the active site. Generation of null mutants in those genes by homologous recombination mutagenesis and protein purification allowed us to correlate each gene with its enzymatic activity. In contrast with all tyrosinases so far studied, the enzyme NP_518458 shows higher monophenolase than o‐diphenolase activity and its initial activity does not depend on the presence of l‐dopa cofactor. On the other hand, protein NP_519622 is an enzyme with a clear preference to oxidize o‐diphenols and only residual monophenolase activity, behaving as a catechol oxidase. These catalytic characteristics are discussed in relation to two other characteristics apart from the six conserved histidines. One is the putative presence of a seventh histidine which interacts with the carboxy group on the substrate and controls the preference for carboxylated and decarboxylated substrates. The second is the size of the residue isosteric with the aromatic F261 reported in sweet potato catechol oxidase which acts as a gate to control accessibility to CuA at the active site.
Computer‐assisted mass spectrometric analysis of naturally occurring and artificially introduced cross‐links in proteins and protein complexes
Authors: de Koning Leo J. , Kasper Piotr T. , Back Jaap Willem , Nessen Merel A. , Vanrobaeys Frank , Van Beeumen Jozef , Gherardi Ermanno , de Koster Chris G , de Jong Luitzen
Published: December 2005

A versatile software tool, virtualmslab, is presented that can perform advanced complex virtual proteomic experiments with mass spectrometric analyses to assist in the characterization of proteins. The virtual experimental results allow rapid, flexible and convenient exploration of sample preparation strategies and are used to generate MS reference databases that can be matched with the real MS data obtained from the equivalent real experiments. Matches between virtual and acquired data reveal the identity and nature of reaction products that may lead to characterization of post‐translational modification patterns, disulfide bond structures, and cross‐linking in proteins or protein complexes. The most important unique feature of this program is the ability to perform multistage experiments in any user‐defined order, thus allowing the researcher to vary experimental approaches that can be conducted in the laboratory. Several features of virtualmslab are demonstrated by mapping both disulfide bonds and artificially introduced protein cross‐links. It is shown that chemical cleavage at aspartate residues in the protease resistant RNase A, followed by tryptic digestion can be optimized so that the rigid protein breaks up into MALDI‐MS detectable fragments, leaving the disulfide bonds intact. We also show the mapping of a number of chemically introduced cross‐links in the NK1 domain of hepatocyte growth factor/scatter factor. The virtualmslab program was used to explore the limitation and potential of mass spectrometry for cross‐link studies of more complex biological assemblies, showing the value of high performance instruments such as a Fourier transform mass spectrometer. The program is freely available upon request.