bluuebunny/crossref_metadata_2025_split huggingface dataset:
Critical nucleation size in the folding of small apparently two‐state proteins
Authors: Bai Yawen , Zhou Hongyi , Zhou Yaoqi 
Published: April 2004

AbstractFor apparently two‐state proteins, we found that the size (number of folded residues) of a transition state is mostly encoded by the topology, defined by total contact distance (TCD) of the native state, and correlates with its folding rate. This is demonstrated by using a simple procedure to reduce the native structures of the 41 two‐state proteins with native TCD as a constraint, and is further supported by analyzing the results of eight proteins from protein engineering studies. These results support the hypothesis that the major rate‐limiting process in the folding of small apparently two‐state proteins is the search for a critical number of residues with the topology close to that of the native state.
Prevalence of dens invaginatus in Jordanian adults
Authors: Hamasha A. A. , Alomari Q. D. 
Published: April 2004

AbstractAim  To assess the prevalence of dens invaginatus in a sample of Jordanian dental patients.Methodology  The data were collected from examination of 3024 radiographs from a random sample of 1660 patients showing 9377 teeth. A tooth was considered having dens invaginatus if an infolding of a radiopaque ribbon‐like structure equal in density to enamel was seen extending from the cingulum into the root canal.Results  Teeth with dens invaginatus were found in 49 subjects out of 1660 subjects examined; thus, the person prevalence was 2.95%. Bilateral dens invaginatus was seen in 12 patients, whereas unilateral dens invaginatus was demonstrated in 37 patients. Dens invaginatus was detected in 61 teeth out of a total of 9377 for a tooth prevalence of 0.65%. Maxillary lateral incisors were the most common teeth affected with the condition (90% of cases).Conclusions  Dens invaginatus is not common, but it is an important anomaly. The availability of such data may alert the dental practitioner to anticipate the percentage of teeth having difficulties during endodontic treatment.
Undergraduate teaching and clinical use of rotary nickel–titanium endodontic instruments: a survey of French dental schools
Authors: Arbab‐Chirani R. , Vulcain J. M. 
Published: April 2004

AbstractAim  To evaluate the impact of rotary nickel–titanium (NiTi) instruments on undergaduate teaching and clinical use in French dental schools and to evaluate the impressions of dental students when learning and using these techniques.Methodology  A questionnaire was mailed to all 16 French undergraduate dental schools. Data were gathered on a range of issues concerning teaching and use of NiTi endodontic techniques.Results  The response rate was 100%. The need for teaching NiTi techniques to dental students was agreed by all schools. Lectures and laboratory courses for rotary NiTi techniques were organized in all of the schools. In 13 of the 16 teaching hospitals, students could use rotary NiTi techniques for canal preparation under the supervision of teaching staff. Similarities were observed in the majority of responses, e.g. type of rotary system taught and used clinically. Some differences were also observed, e.g. the association of hand files to rotary NiTi instruments and at what stage in the undergraduate curriculum rotary instruments were introduced.Conclusion  There was a national consensus over the need for undergraduate teaching of rotary NiTi systems in France. These techniques had made a substantial impact in endodontic teaching and were widely taught and used in French dental schools.
Marginal adaptation of mineral trioxide aggregate (MTA) compared with amalgam as a root‐end filling material: a low‐vacuum (LV) versus high‐vacuum (HV) SEM study
Authors: Shipper G. , Grossman E. S. , Botha A. J. , Cleaton‐Jones P. E. 
Published: April 2004

AbstractAim  To compare the marginal adaptation of mineral trioxide aggregate (MTA) or amalgam root‐end fillings in extracted teeth under low‐vacuum (LV) versus high‐vacuum (HV) scanning electron microscope (SEM) viewing conditions.Methodology  Root‐end fillings were placed in 20 extracted single‐rooted maxillary teeth. Ten root ends were filled with MTA and the other 10 root ends were filled with amalgam. Two 1 mm thick transverse sections of each root‐end filling were cut 0.50 mm (top) and 1.50 mm (bottom) from the apex. Gap size was recorded at eight fixed points along the dentine–filling material interface on each section when uncoated wet (LV wet (LVW)) and dry under LV (0.3 Torr) in a JEOL JSM‐5800 SEM and backscatter emission (LV dry uncoated (LVDU)). The sections were then air‐dried, gold‐coated and gap size was recorded once again at the fixed points under HV (10−6 Torr; HV dry coated (HVDC)). Specimen cracking, and the size and extent of the crack were noted.Results  Gap sizes at fixed points were smallest under LVW and largest under HVDC SEM conditions. Gaps were smallest in MTA root‐end fillings. A General Linear Models Analysis, with gap size as the dependent variable, showed significant effects for extent of crack in dentine, material and viewing condition (P = 0.0001).Conclusions  This study showed that MTA produced a superior marginal adaptation to amalgam, and that LVW conditions showed the lowest gap size. Gap size was influenced by the method of SEM viewing. If only HV SEM viewing conditions are used for MTA and amalgam root‐end fillings, a correction factor of 3.5 and 2.2, respectively, may be used to enable relative comparisons of gap size to LVW conditions.
Efficacy of antibiotics to strains of periodontopathogenic bacteria within a single species biofilm – an in vitro study
Authors: Eick S. , Seltmann T. , Pfister W. 
Published: April 2004

AbstractObjectives: This study examined differences in the efficacy of antibiotics against a single strain of three periodontal pathogens grown in an artificial biofilm.Methods: Single species biofilms were established with artificial saliva and one of the following bacterial strains: Actinobacillus actinomycetemcomitans Y4, Streptococcus constellatus 384b (a clinical isolate) and Porphyromonas gingivalis ATCC 33277. The efficacy of the antibiotics clindamycin, doxycycline, metronidazole, and moxifloxacin to these bacteria was determined using concentrations up to 100‐fold minimal inhibitory concentration (MIC) to planctonic bacteria over 48 h.Results: The ability of the bacteria to form a biofilm varied. The biofilms of S. constellatus 384b and A. actinomycetemcomitans Y4 contained more viable bacteria and showed a larger thickness in SEM photographs than those of P. gingivalis ATCC 33277. The antibiotics tested showed different efficacy for the different strains. Moxifloxacin was the most efficient antibiotic: onefold MIC was sufficient to eliminate A. actinomycetemcomitans Y4 and P. gingivalis ATCC 33277 after 48 h. However, only the 50‐fold MIC completely eradicated S. constellatus 384b. SEM photographs underlined the damaging effect of moxifloxacin on the biofilm structure.Conclusion: The complete removal of bacteria by the use of antibiotics alone seems to be impossible when taking into account MIC values and the level of antibiotics in gingival fluid.
Closed‐End Fund Discounts and Expected Investment Performance
Authors: Ferguson Robert , Leistikow Dean 
Published: April 2004

AbstractThis article provides empirical support for the theory that closed‐end fund discounts reflect expected investment performance. Evidence is presented to explain how equity closed‐end fund initial public offerings (IPOs) can sell at a premium when existing funds sell at a discount and why the initial IPO premiums decay after the IPO. Relative premium decay data are presented. Tests on (1) the relation between relative premium changes and investment performance following IPOs, (2) relative premium mean‐reversion following management changes, and (3) net redemptions following closed‐end fund open‐endings for funds trading at pre‐open‐ending announcement discounts individually support and collectively strongly support the theory.
Bank Mergers and Insider Nontrading
Authors: Madison Tom , Roth Greg , Saporoschenko Andy 
Published: April 2004

AbstractInsiders with nonpublic information that their firms are acquisition targets can profit by purchasing their firms' stock or by delaying planned sales of their firms' stock. Under current securities laws, insiders who execute the former strategy expose themselves to civil and criminal liability, whereas insiders who execute the latter strategy do not. Using a sample of bank mergers, we find that target bank insiders significantly decrease both share purchases and share sales before merger announcements. These findings suggest that securities laws effectively deter some forms of illegal insider trading and that insiders exploit opportunities to profit legally from nonpublic information.
The Pricing of Sequential Bank Loans
Authors: Athavale Manoj , Edmister Robert O. 
Published: April 2004

AbstractThe theory of financial intermediation assigns banks a unique role in the resolution of information asymmetry. Banks, in general, obtain private information about the borrower and the project during the screening of loan applicants and during the monitoring of loan recipients. Incumbent banks, in particular, utilize information obtained while monitoring previous loan extensions to resolve information asymmetry when granting subsequent loans. We examine the rate on a sequence of loans to a borrower and find that the incumbent bank information advantage has finite magnitude and is quickly reflected in the pricing of the second loan. We also find that the lending relationship does not deteriorate to the detriment of the borrower. This study also provides further evidence supporting the hypothesis that an incumbent bank resolves information asymmetry during the monitoring of loan extensions.
Specialists, Limit‐Order Traders, and the Components of the Bid‐Ask Spread
Authors: Chung Kee H. , Van Ness Bonnie F. , Van Ness Robert A. 
Published: April 2004

AbstractThis study compares the components of the bid‐ask spread estimated from quotes that reflect the trading interest of specialists with those estimated from limit‐order quotes and all available quotes for a sample of New York Stock Exchange (NYSE) stocks. The results show that the adverse selection component of the spread estimated from specialist quotes is significantly smaller than the corresponding figures from limit‐order quotes and entire quotes. We interpret this as evidence that NYSE specialists transfer at least a part of adverse selection costs to outsiders through the discretionary use of limit orders. Our results show that the estimation/interpretation of the components of the spread using quote data that include both specialist and limit‐order interests is problematic.
To Trade or Not to Trade: The Effect of Broker Search and Discretionary Trading on Securities Market Performance
Authors: Zhang Wei , Li Jinliang , Wu Chunchi 
Published: April 2004

AbstractIn this article we examine the interaction of brokerage search with the Bayesian learning behavior of competitive dealers under asymmetric information. We particularly focus on the effects of price search and discretionary trading on the performance of a dealer market. A search process is incorporated into a model in which brokers determine their reservation price and whether to continue their trades. The model enables us to uncover the interrelationships among search cost, bid‐ask spread, and price volatility. We show that both spread revision and price volatility are dependent upon the optimal search process, inventory fluctuation, and search cost. Furthermore, our model predicts a negative relationship between price volatility and liquidity trading volume.
Force‐independent expression of c‐fos mRNA by endothelin‐1 in rat intact small mesenteric arteries
Authors: Buus C. L. , Kristensen H. B. , Bakker E. N. T. P. , Eskildsen‐Helmond Y. E. G. , Mulvany M. J. 
Published: April 2004

AbstractAim:  Wall stress‐independent signalling pathways were studied for endothelin‐1 (ET‐1)‐induced c‐fos expression in rat intact mesenteric small arteries.Methods:  Arteries were kept unmounted in Krebs buffer, equilibrated for 1 h and stimulated with vasoactive substances for 15–60 min. The c‐fos mRNA expression was determined by real‐time polymerase chain reaction.Results:  Stimulation with fetal bovine serum (FBS), phorbol 12‐myristate 13‐acetate (PMA) and ET‐1 caused about a doubling of c‐fos mRNA. The ET‐1‐induced c‐fos expression was steady (15–60 min) and was inhibited by the inhibitor of the ETA receptor, BQ‐123. Platelet‐derived growth factor‐B, angiotensin II and U46619 did not cause increased c‐fos mRNA levels. The broad specificity inhibitor staurosporine inhibited the response to ET‐1, but inhibitors of Rho‐A kinase and phosphatidylinositol 3‐kinase had no effect. However, inhibitors to tyrosine kinases, the MAP kinases [extracellular signal‐regulated kinase 1/2 (ERK1/2), c‐Jun amino‐terminal kinase, p38], and to conventional protein kinase C showed no inhibition. Consistent with these findings, ET‐1 did not cause activation of ERK1/2, a finding also seen in vessels held under pressure. In contrast, ET‐1‐induced c‐fos expression was inhibited by the calcium chelator BAPTA, suggesting a role for intracellular calcium. This possibility was supported by the finding that raising the extracellular K+ concentration caused increased expression of c‐fos in a concentration‐dependent manner.Conclusion:  The results suggest that in the absence of wall stress, ET‐1 is able to induce increased expression of c‐fos independent of traditional growth pathways, such as MAP kinase. The mechanism appears to be calcium‐dependent.
Haemodynamic effects of dopexamine on postprandial splanchnic hyperaemia
Authors: Bartsch S. , Brüning A. , Reimann F. M. , Ludwig D. 
Published: April 2004

AbstractBackground  The synthetic β2‐adrenergic and dopaminergic agonist dopexamine is supposed to prevent splanchnic hypoperfusion in critically ill patients, thus potentially interacting with haemodynamic effects of early enteral nutrition. However, precise mechanism of action and interaction with postprandial splanchnic hyperaemia of the drug are largely unknown, even in healthy subjects.Materials and methods  Twelve healthy volunteers received dopexamine 1 µg kg−1 min−1 and dopexamine and placebo (NaCl 0·9%) 3 µg kg−1 min−1 in a randomized, double‐blinded order (crossover‐design). Splanchnic (Doppler ultrasound) and systemic (noninvasive cardiac monitoring) haemodynamic parameters were assessed at baseline and during infusion (fasted as well as 15, 30, 45 and 60 min after a standard liquid meal).Results  In fasted humans, dopexamine enhanced time‐averaged maximum velocity (TAMX) in the superior mesenteric artery (1 µg + 40%; 3 µg + 82%, P < 0·05), portal vein (+ 63%; + 121%, P < 0·05) and femoral artery (+ 66%; + 87%, P < 0·05), in proportion to the increase of cardiac index (+ 33%; + 77%, both P < 0·05). In the postprandial state, TAMX rose significantly in the superior mesenteric artery (+ 139%) and portal vein (+ 68%) in the placebo group, showing the same absolute extent as dopexamine. The physiological postprandial buffer response of hepatic artery was conserved under all conditions.Conclusions  Continuous infusion of dopexamine enhances mesenterial and portal perfusion in a dose‐dependent manner without affecting the extent of physiological postprandial hyperaemia. Thus, dopexamine and enteral nutrition may interact with splanchnic haemodynamics by different pathways.
Vasodilator mRNA levels are increased in the livers of portal hypertensive NO‐synthase 3‐deficient mice
Authors: Biecker E. , Sägesser H. , Reichen J. 
Published: April 2004

AbstractBackground/aims  Nitric oxide synthase (NOS) 3‐deficient (NOS‐3 KO) mice have an increased systemic arterial pressure but develop portal hypertension to the same extent as wildtype (WT) mice. We hypothesized that other vasodilators in the portal circulation compensate for the lack in NOS‐3 activity. We used quantitative PCR as a screening method to identify mediators that possibly compensate for NOS‐3 in NOS‐3 KO mice.Methods  Mean arterial pressure (MAP) and portal venous pressure (PVP) were measured in the anaesthetized animal. mRNA levels in whole liver tissue were determined by quantitative RT‐PCR.Results  NOS‐3 KO mice had a significantly higher mean arterial pressure than WT mice, but portal venous pressure did not differ. Bile duct ligation (BDL) induced a drop in MAP and a rise in PVP in both groups. Bile duct ligation induced a significant increase in mRNA levels of the cannabinoid receptor (CB)‐1, adrenomedullin and NOS‐2 in the liver of NOS‐3 KO and WT mice. Nitric oxide synthase‐1 and NOS‐3 mRNA levels were elevated in BDL WT mice compared with sham‐operated WT mice. Higher mRNA levels of CB‐1, NOS‐1 and the adrenomedullin receptor were found in sham‐operated NOS‐3 KO mice compared with sham‐operated WT mice.Conclusions  We used quantitative PCR as a screening method to identify vasodilative mediators that might be involved in the compensation for the lack of NOS‐3 activity in NOS‐3 KO mice. Elevated mRNA levels in sham‐operated NOS‐3 KO mice compared with sham‐operated WT mice were demonstrated for CB‐1, NOS‐1 and the adrenomedullin receptor.
Effect of homocysteine‐lowering treatment with folic acid plus vitamin B6 on cerebrovascular atherosclerosis and white matter abnormalities as determined by MRA and MRI: a placebo‐controlled, randomized trial
Authors: Vermeulen E. G. J. , Stehouwer C. D. A. , Valk J. , Van Der Knaap M. , Van Den Berg M. , Twisk J. W. R. , Prevoo W. , Rauwerda J. A. 
Published: April 2004

AbstractBackground  A high plasma homocysteine concentration is an independent risk factor for large and possibly small vessel disease. We investigated the effects of homocysteine‐lowering treatment with folic acid plus vitamin B6 on markers of cerebrovascular atherosclerosis and cerebral microangiopathy.Materials and Methods  Using 158 healthy siblings (mean age 46·0 ± 7·6 years) of patients with premature atherosclerotic disease, we performed a randomized, placebo‐controlled trial using 5 mg of folic acid plus 250 mg of vitamin B6 daily (n = 78) or placebo medication (n = 80). Participants were followed for 2 years with magnetic resonance angiography (MRA) (carotid stenosis; carotid and/or vertebral elongation) and magnetic resonance imaging (MRI) (white matter abnormalities; cerebral atrophy).Results  Seventeen (10·8%) subjects refused MRA/MRI owing to claustrophobia and were excluded. From the remaining 141 participants, 68 received vitamin and 73 received placebo medication [42 (61·8%) and 48 (65·8%) had postmethionine hyperhomocysteinaemia, respectively]. Twenty‐four participants (15·2%; 10 in the treatment and 14 in the placebo group) did not complete both years of the trial. Vitamin treatment was associated with an increase in plasma folate (13‐fold vs. placebo; P < 0·001) and vitamin B6 (8·8‐fold; P < 0·001). Fasting and postmethionine total homocysteine concentrations decreased 38·7% (95% CI, 27·4–50·0) and 29·1% (95% CI, 19·2–39·0) vs. placebo (all P < 0·001). During follow up six individuals in the vitamin‐treated and 11 in the placebo‐treated group deteriorated in their outcome measurements. Vitamin treatment, as compared with placebo, was associated with nonsignificantly improved outcomes on both MRA and MRI outcome measurements (odds ratio 0·48; 95% CI 0·17–1·41; P = 0·18 and 0·48; CI 0·14–1·60; P = 0·23, respectively).Conclusions  These results could indicate a possible favourable effect of homocysteine‐lowering treatment on cerebrovascular atherosclerosis and cerebral microangiopathy among healthy siblings of patients with premature atherosclerotic disease, but larger trials are required to establish this with certainty.
Effects of endothelin‐1 on portal‐systemic collaterals of common bile duct‐ligated cirrhotic rats
Authors: Chan C.‐C. , Wang S.‐S. , Lee F.‐Y. , Chang F.‐Y. , Lin H.‐C. , Hou M.‐C. , Huang H.‐C. , Lee S.‐D. 
Published: April 2004

AbstractBackground/Aims  Endothelin‐1 (ET‐1) may induce intrahepatic vasoconstriction and consequently increase portal pressure. Endothelin‐1 has been shown to exert a direct vasoconstrictive effect on the collateral vessels in partially portal vein‐ligated rats with a high degree of portal‐systemic shunting. This study investigated the collateral vascular responses to ET‐1, the receptors in mediation and the regulation of ET‐1 action by nitric oxide and prostaglandin in cirrhotic rats with a relatively low degree of portal‐systemic shunting.Methods  The portal‐systemic collaterals of common bile duct‐ligated (BDL) cirrhotic rats were tested by in situ perfusion. The concentration‐response curves of collaterals to graded concentrations of ET‐1 (10−10−10−7 m) with or without BQ‐123 (ETA receptor antagonist, 2 × 10−6 m), BQ‐788 (ETB receptor antagonist, 10−7 m) or both were recorded. In addition, the collateral responses to ET‐1 with preincubation of Nω‐nitro‐L‐arginine (NNA, 10−4 M), indomethacin (INDO, 10−5 M) or in combination were assessed.Results  Endothelin‐1 significantly increased the perfusion pressures of portal‐systemic collaterals. The ET‐1‐induced constrictive effects were inhibited by BQ‐123 or BQ‐123 plus BQ‐788 but not by BQ‐788 alone. The inhibitory effect was greater in the combination group. Pretreatment of NNA or NNA plus INDO equivalently enhanced the response of ET‐1 while pretreatment of INDO alone exerted no effect.Conclusion  Endothelin‐1 has a direct vasoconstrictive effect on the collaterals of BDL cirrhotic rats, mainly mediated by ETA receptor. Endogenous nitric oxide may play an important role in modulating the effects of ET‐1 in the portal‐systemic collaterals of BDL cirrhotic rats.
Insulin‐like growth factors and pancreas beta cells
Authors: Van Haeften T. W. , Twickler Th. B. 
Published: April 2004

AbstractInsulin‐like growth factors (IGFs) have been implicated in normal growth, and especially foetal pancreas beta‐cell development. As low birth weight has been implicated in the development of obesity and type 2 diabetes, much research has evolved into the importance of IGF and their signalling pathways for pancreas beta‐cell development, and for type 2 diabetes. Insulin‐like growth factor‐I signalling has a lot in common with insulin signalling, and is involved in diverse cellular effects such as antiapoptosis, protein synthesis, cell growth and mitogenesis. Insulin‐like growth factor‐II can be bound by the insulin receptor A subtype and the IGF‐1 receptor, which may explain its antiapoptotic effect.Various knock‐out model studies indicate that absence of IGF‐I or the IGF‐1 receptor is critical for foetal and postnatal growth. Similarly, knock‐out models of post‐receptor molecules (such as IRS‐2) point to the physiological role of IGFs for pancreas beta‐cell development. A beta‐cell‐specific IGF‐1 receptor knock out model indicates the importance of IGF‐I for beta‐cell function. The Goto‐Kakizaki (GK) rat, a model for diabetes, has insufficient beta‐cell development, which may be related to its defective IGF‐II synthesis.As normal pancreas beta cells adapt to the prevailing insulin resistance with increasing beta‐cell function, it is possible that insulin resistance interacts with IGF signalling in pancreas beta cells.