bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tracheal sealing characteristics of pediatric cuffed tracheal tubes
Authors: Dullenkopf Alexander , Schmitz Achim , Gerber Andreas C. , Weiss Markus 
Published: September 2004

SummaryBackground : The aim of the study was to compare sealing characteristics of the new Microcuff pediatric tracheal tube featuring a high volume–low pressure (HVLP) cuff with ultrathin membrane with three conventional pediatric cuffed tracheal tubes.Methods : After obtaining approval of the local ethical committee, 80 children aged 2–4 years were tracheally intubated with the following tubes (i.d. 4.0 mm) in random order: Microcuff P‐HVLP, Mallinckrodt Hi‐Contour P, Rüschelit Super Safety Clear, and Sheridan CF. Cuff pressure to prevent air leakage at standardized ventilator setting (PIP 20 cm H2O/PEEP 5 cm H2O/RR 20 min−1) was assessed within 5 min after intubation by auscultation of audible sounds at the mouth. Cuff pressures required with each group were compared with Kruskall–Wallis test (P < 0.05). Values are median and range.Results : No significant differences in patient characteristics were found between the four groups. The Microcuff tube required significantly lower sealing pressures [11 cm H2O (6–26)] compared with the other tracheal tube brands [Mallinckrodt: 36 cm H2O (18–48); Rüschelit: 21 cm H2O (8–46); Sheridan: 26 cm H2O (18–60), (P < 0.0001)].Conclusion : This preliminary investigation suggests that the new Microcuff pediatric tracheal tube with ultrathin high volume–low pressure cuff membrane allows effective tracheal sealing at very low cuff pressures. This represents a benefit for children with regard to their lower mucosal perfusion pressures compared with adult patients.
The effect of remifentanil on cerebral blood flow velocity in children anesthetized with propofol1
Authors: Lagace Annie , Karsli Cengiz , Luginbuehl Igor , Bissonnette Bruno 
Published: September 2004

SummaryBackground : Cerebrovascular stability and rapid anesthetic emergence are desirable features of a neuroanesthetic regimen. In this randomized crossover study the effect of a low‐dose remifentanil infusion on cerebral blood flow velocity (CBFV) in children anesthetized with propofol was evaluated.Methods : Twenty healthy children aged 1–6 years undergoing urological surgery were enrolled. Following face mask induction with sevoflurane, anesthesia was maintained with a standardized propofol infusion. Rocuronium was used to facilitate tracheal intubation and normothermia, and normocapnia were maintained. All children received a caudal epidural block, and a transcranial Doppler probe was placed to measure middle cerebral artery blood flow velocity (Vmca). Each patient received a remifentanil regimen of 0.5 μg·kg−1 followed by 0.2 μg·kg−1·min−1 in a predetermined order of remifentanil + propofol or propofol alone. Vmca, mean arterial pressure (MAP) and heart rate (HR) were recorded simultaneously at equilibrium with and without remifentanil.Results : The combination of remifentanil and propofol caused an 8.1% decrease in MAP (P = 0.0005) and an 11.8% decrease in HR (P < 0.0001) compared with propofol alone. Vmca was not different between the two groups (P = 0.4041).Conclusion : The addition of remifentanil to propofol anesthesia in children causes a reduction in MAP and HR without affecting CBFV. This may imply that cerebral blood pressure autoregulation is preserved in children under propofol and remifentanil anesthesia.
Remifentanil vs fentanyl/morphine for pain and stress control during pediatric cardiac surgery
Authors: Bell G. , Dickson U. , Arana A. , Robinson D. , Marshall C. , Morton N. 
Published: September 2004

SummaryBackground : Remifentanil is a short acting, potent synthetic opioid that does not accumulate after infusion or repeated bolus doses. It may be rapidly titrated to the requirements of individual patients. Titrated infusion of remifentanil may be able to provide potent analgesia required for pediatric cardiac surgery and obtund the stress response in theater whilst not having the persistent respiratory depression and sedation seen with longer acting opioids.Methods : Twenty patients were randomized to receive a titrated infusion of remifentanil (0–1 μg·kg−1·min−1) or a standard dose of fentanyl (30 μg·kg−1) prebypass plus morphine (1 mg·kg−1) on rewarming. Blood samples for glucose and cortisol were taken at regular intervals from induction through bypass and into the first 24 h of postoperative intensive care. In addition to biochemical indicators of the stress response we recorded baseline hemodynamic parameters and any acute physiological events.Results : Ten patients received morphine, seven received remifentanil. There were no statistically significant differences between the two treatment groups in cortisol measurements, mean arterial pressure or heart rate recordings. In the last time period the remifentanil group had a larger rise in blood glucose concentration (baseline 3.9, rise 3 mmol·l−1) than the fentanyl/morphine group (baseline 4.2 rise 1.9 mmol·l−1), CI −4.3 to −0.2.Conclusions : The only significant difference was in glucose in the postbypass time periods. Although statistically significant, this difference is insufficient evidence of increased stress in the remifentanil group. The results show that in the patients studied there was no clinically important difference between the two techniques.
Levobupivacaine spinal anesthesia in neonates: a dose range finding study
Authors: Frawley Geoff P , Farrell Tanya , Smith Sarah 
Published: September 2004

SummaryBackground : Our aim was to determine the clinical efficacy of levobupivacaine for awake spinal anesthesia in ex‐premature infants having lower abdominal surgery. The secondary aim was to determine the minimum local analgesic dose (MLAD) defined as the median effective local anesthetic dose for spinal anesthesia in neonates.Methods : Fifty neonates <55 weeks postconceptional age having lower abdominal surgery were enrolled. The dose of levobupivacaine was determined by up–down sequential allocation. The first infant received 1.25 mg·kg−1 0.5% levobupivacaine with subsequent doses determined by the response of the previous patient. Dose interval was 0.25 mg·kg−1.Results : There were no significant adverse effects attributable to levobupivacaine. Success rates for 1.25, 1, 0.75 and 0.5 mg·kg−1 were 100, 83, 81 and 46%, respectively. Mean duration (95% confidence interval) of lower limb motor blockade was 81.7 min (75.8–87.6 min). Duration of anesthesia far exceeded surgical duration in all but one case. The up–down sequences were analyzed with the Dixon and Massey method. The motor block MLAD (95% confidence interval) was 0.48 mg·kg−1 (0.42–0.54). Probit analysis was used to compare calculated ED50 and to calculate an ED95 by extrapolation of data into the clinical range. The ED50 (95% C.I.) was 0.52 mg·kg−1 (0.30–0.73). The calculated ED95 was 1.14 mg·kg−1 (0.78–1.50). These values were confirmed by logit analysis.Conclusions : Levobupivacaine is an effective agent for spinal anesthesia in neonates at a recommended dose of 1 mg·kg−1. It appears to be of equivalent potency to racemic bupivacaine for motor blockade in ex‐premature infants requiring lower abdominal surgery.
Exaggerated insulin secretion in Pima Indians and African‐Americans but higher insulin resistance in Pima Indians compared to African‐Americans and Caucasians
Authors: Stefan N. , Stumvoll M. , Weyer C. , Bogardus C. , Tataranni P. A. , Pratley R. E. 
Published: September 2004

AbstractAims  African‐Americans have a higher prevalence of Type 2 diabetes than Caucasians, but a lower prevalence than Pima Indians. Studies suggest that both African‐Americans and Pima Indians are more insulin resistant and have higher acute insulin secretory responses to glucose than Caucasians; however, a direct comparison between these three populations is lacking.Methods  We measured insulin secretory responses to intravenous glucose (acute insulin response, AIR, 25 g ivGTT); insulin action at physiological (M‐low) and supra‐physiological (M‐high) levels of hyperinsulinaemia (2‐step hyperinsulinaemic clamp); basal and insulin‐suppressed endogenous glucose production in 30 African‐Americans, 30 Pima Indians and 30 Caucasians with normal glucose tolerance who were carefully matched for age, sex, and body fat (hydrodensitometry or DEXA). A subgroup of 24 subjects from each group additionally underwent a standardized mixed meal test.Results  M‐low was lower in Pima Indians (0.50 ± 0.03) compared to Caucasians (0.59 ± 0.02, P = 0.02) and African‐Americans [0.58 ± 0.03 mg/kgEMBS/min, log10 (means ± SE), P = 0.03] but was not different between African‐Americans and Caucasians. Basal endogenous glucose production was lower in Pima Indians (2.43 ± 0.06) compared to African‐Americans (2.70 ± 0.06, P = 0.02) and was not different between Pima Indians and Caucasians (2.59 ± 0.09 mg/kgEMBS/min) or African‐Americans and Caucasians (all P > 0.18). Insulin‐suppressed endogenous glucose production during the clamp was not different among the groups (all P > 0.40). AIR was higher in both African‐Americans (13.51 ± 0.26) and Pima Indians (13.72 ± 0.27) compared to Caucasians (12.33 ± 0.25 pm, log10, both P < 0.01). The areas under the curve for glucose in response to the oral glucose tolerance test and mixed meal test were higher in Pima Indians compared to African‐Americans (P = 0.03 and P = 0.03, respectively) and Caucasians (P = 0.01, mixed meal test), but not different between African‐Americans and Caucasians.Conclusions  Exaggerated glucose‐stimulated insulin secretion, manifested initially as an increased response to an intravenous glucose challenge, appears to be a characteristic in people with normal glucose tolerance at higher risk for diabetes. Lower whole‐body insulin sensitivity in Pima Indians compared to African‐Americans, however, may contribute to the higher risk for Type 2 diabetes in Pima Indians compared to African‐Americans.
A pilot quality assurance scheme for diabetic retinopathy risk reduction programmes
Authors: Garvican L. , Scanlon P. H. 
Published: September 2004

AbstractAims  We describe a pilot study of measurement of quality assurance targets for diabetic retinopathy screening and performance comparison between 10 existing services, in preparation for the roll‐out of the national programme.Background  In 1999 the UK National Screening Committee approved proposals for a national diabetic retinopathy risk reduction programme, including recommendations for quality assurance, but implementation was held pending publication of the National Service Framework for Diabetes. Existing services requested the authors to perform a pilot study of a QA scheme, indicating willingness to contribute data for comparison.Methods  Objectives and quality standards were developed, following consultation with diabetologists, ophthalmologists and retinal screeners. Services submitted 2001/2 performance data, in response to a questionnaire, for anonymization, central analysis and comparison.Results  The 17 quality standards encompass all aspects of the programme from identification of patients to timeliness of treatment. Ten programmes took part, submitting all the data available. All returns were incomplete, but especially so from the optometry‐based schemes. Eight or more services demonstrated they could reach the minimum level in only five of the 17 standards. Thirty per cent could not provide coverage data. All were running behind. Reasons for difficulties in obtaining data and/or failing to achieve standards included severe under‐funding and little previous experience of QA. Information systems were limited and incompatible between diabetes and eye units, and there was a lack of co‐ordinated management of the whole programme.Conclusion  Quality assurance is time‐consuming, expensive and inadequately resourced. The pilot study identified priorities for local action. National programme implementation must involve integral quality assurance mechanisms from the outset.
Release of endothelium‐associated proteins into blood by injection of heparin in normal subjects and in patients with Type 1 diabetes
Authors: Myrup B. , Yokoyama H. , Kristiansen O. P. , Østergaard P. B. , Olivecrona T. 
Published: September 2004

AbstractAims  Disturbances in heparan sulphate proteoglycans in patients with diabetic nephropathy might contribute to the pathogenesis of vascular disease in these patients. To investigate this possible link, we measured the heparin‐induced, immediate release of eight proteins with heparan sulphate binding properties in patients with nephropathy.Methods  We studied three groups, Type 1 diabetic patients with (n = 10) or without (n = 15) albuminuria and matched controls (n = 12). Blood samples were obtained before and 5 min after the injection of 40 anti‐Xa IU low molecular weight heparin/kg body weight.Results  Lipoprotein lipase increased more in diabetic patients without albuminuria than in controls and patients with albuminuria [261 (170–293) vs. 177 (103–438), P < 0.05 and 203 (159–280) mU/ml, P < 0.05]. Total tissue factor pathway inhibitor increased more in the diabetic patients [284 (198–449) and 275 (243–399)] than in the controls [221 (169–289) ng/ml, P < 0.005]. Vitronectin increased significantly only in the diabetic patients with albuminuria. The remaining proteins did not increase significantly (antithrombin, von Willebrand factor, fibronectin) or increased equally in the three investigated groups (extracellular superoxid dismutase and platelet factor 4).Conclusions  The different release of lipoprotein lipase and vitronectin in diabetic subjects with and without albuminuria may reflect novel aspects of vascular derangement in patients with albuminuria.
Prevalence and clinical characteristics of metabolic syndrome in a rural population of South Korea
Authors: Kim E. S. , Han S.‐M. , Kim Y. I. , Song K.‐H. , Kim M.‐S. , Kim W. B. , Park J.‐Y. , Lee K.‐U. 
Published: September 2004

AbstractAims  To determine the prevalence of metabolic syndrome according to the criteria of the Adult Treatment Panel III (ATP III) and the World Health Organization (WHO).Methods  Data were collected from 1108 subjects over 40 years of age in the Chongup district, a rural area of South Korea. We evaluated the prevalence and clinical characteristics of metabolic syndrome according to the two criteria.Results  According to the ATP III criteria, the prevalence of central obesity was 0.2% in men and 27.3% in women, which is much lower than the prevalence of central obesity in Americans. However, the prevalence of metabolic syndrome was similar to the prevalence in Americans. Of the Korean subjects over 40 years of age, 29.4% and 39.2% had metabolic syndrome according to the ATP III and WHO criteria, respectively. Metabolic syndrome according to the ATP III criteria was associated with insulin resistance, but not with microalbuminuria.Conclusions  Metabolic syndrome has a high prevalence in South Koreans despite the low prevalence of obesity and/or central obesity.
Interdependence and dynamic linkages between the emerging stock markets of South Asia
Authors: Narayan Paresh , Smyth Russell , Nandha Mohan 
Published: September 2004

AbstractThe present article examines the dynamic linkages between the stock markets of Bangladesh, India, Pakistan and Sri Lanka using a temporal Granger causality approach by binding the relationship among the stock price indices within a multivariate cointegration framework. We also examine the impulse response functions. Our main finding is that in the long run, stock prices in Bangladesh, India and Sri Lanka Granger‐cause stock prices in Pakistan. In the short run there is unidirectional Granger causality running from stock prices in Pakistan to India, stock prices in Sri Lanka to India and from stock prices in Pakistan to Sri Lanka. Bangladesh is the most exogenous of the four markets, reflecting its small size and modest market capitalization.
Intracellular Mg2+ interacts with structural determinants of the narrow constriction contributed by the NR1‐subunit in the NMDA receptor channel
Authors: Wollmuth Lonnie P. , Kuner Thomas , Sakmann Bert 
Published: September 2004

N‐methyl‐D‐aspartate (NMDA) receptor channels are blocked by intracellular Mg2+ in a voltage‐dependent manner. Amino acid residues positioned at or near the narrow constriction that interact with intracellular Mg2+ were identified in recombinant NR1‐NR2A channels expressed in Xenopus oocytes or human embryonic kidney (HEK) 293 cells.
In the absence of extracellular Ca2+, the block of wild‐type channels by intracellular Mg2+ measured using macroscopic currents showed a voltage dependence (δ) of around 0.38 and a voltage‐independent affinity for the channel of 4 mM. These parameters were independent of the Mg2+ concentration (0.05‐10 mM), and were indistinguishable from those found for the reduction of single channel amplitudes under the same ionic conditions. Under biionic conditions with high intracellular Mg2+ and K+ extracellularly, Mg2+ was weakly permeant. Mg2+ efflux, however, attenuated the block only at positive potentials (> +80 mV).
Substitutions of the N‐site asparagine in the NR1‐subunit altered intracellular Mg2+ block over physiological membrane potentials (+10 to +50 mV). Substitution of glycine, glutamine or serine attenuated the extent of block whereas the negatively charged aspartate enhanced it, consistent with the side chain of the native asparagine at this position contributing to a blocking site for intracellular Mg2+.
Substitutions of the N‐site or N + 1 site asparagine in the NR2A‐subunit, which form a blocking site for extracellular Mg2+, also altered the block by intracellular Mg2+. However, for the NR2A‐subunit N‐site asparagine, the block was reduced but only at non‐physiological high potentials (> +70 mV).
The NR2A‐subunit N + 1 site asparagine, which together with the NR1‐subunit N‐site asparagine forms the narrow constriction of the channel, also contributed to a blocking site for intracellular Mg2+. However, it did so to a lesser extent than the NR1‐subunit N‐site and in a manner different from its contribution to a blocking site for extracellular Mg2+.
It is concluded that intracellular Mg2+ interacts with residues that form the narrow constriction in the NMDA receptor channel with the N‐site asparagine of the NR1‐subunit representing the dominant blocking site. Thus, intracellular Mg2+ interacts with different asparagine residues at the narrow constriction than extracellular Mg2+, although the two blocking sites are positioned very close to each other.
Non‐pore lining amino acid side chains influence anion selectivity of the human CFTR Cl− channel expressed in mammalian cell lines
Authors: Linsdell Paul , Zheng Shu‐Xian , Hanrahan John W. 
Published: September 2004

The effects of individually mutating two adjacent threonine residues in the sixth membrane‐spanning region (TM6) of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl− channel on permeation properties were examined using patch clamp recording from mammalian cell lines stably expressing human CFTR.
A number of mutations of T338 significantly affected the permeation properties of the channel. Increases and decreases in single channel conductance were observed for different mutants. Anion selectivity was strongly affected, with no two channel variants sharing the same selectivity sequence. Several mutations led to strong inward rectification of the macroscopic current‐voltage relationship. The effects of these mutations on permeation properties were correlated with the size of the amino acid side chain substituted, rather than its chemical nature.
Most mutations of T339 resulted in a lack of functional channel expression and apparent misprocessing of the protein. One mutant, T339V, was characterized in detail; its permeation properties were significantly altered, although these effects were not as strong as for T338 mutations.
These results suggest an important role for T338 in controlling the permeation properties of the CFTR Cl− channel. It is suggested that mutation of this residue alters the interaction between permeating anions and the channel pore via an indirect effect on the orientation of the TM6 helix.
Internal Mg2+ block of recombinant NMDA channels mutated within the selectivity filter and expressed in Xenopus oocytes
Authors: Kupper Jürgen , Ascher Philippe , Neyton Jacques 
Published: September 2004

The NMDA receptor channel is blocked by both external and internal Mg2+ ions, which are assumed to bind inside the channel on each side of a central barrier. We have analysed the internal Mg2+ block in recombinant NR1‐NR2A NMDA receptors expressed in Xenopus oocytes. We have determined the effects of mutations of two asparagines that line the selectivity filter of the channel, one located within the NR1 subunit (N598) and the other within the NR2A subunit (N596).
The whole‐cell current‐voltage relation of wild‐type NMDA channels shows inward rectification that reflects the voltage‐dependent block produced by the internal Mg2+ of the oocyte. This inward rectification is slightly reduced in the NR2 mutant (N596S) but is abolished in the NR1 mutants (N598Q and N598S). This suggests that the NR1 asparagine plays a larger role than the NR2 asparagine in controlling the internal Mg2+ block.
Single‐channel current‐voltage relations confirm that the internal Mg2+ block is reduced in both the NR1 and NR2 mutants. However, the reduction is small and is similar for the two families of mutants.
The discrepancy between whole‐cell and single‐channel data is partly due to differential effects of internal Mg2+ on the open probabilities of the two conductance states present in NR1 mutant channels.
The results suggest that mutations of NR1 and NR2 asparagines lower the central barrier to Mg2+. An additional contribution of the NR2 asparagine to the external Mg2+ binding site (and possibly to the external barrier that controls access to this site) may account for the marked relief of external Mg2+ block produced by the NR2 mutation.
Transfer of rapid inactivation and sensitivity to the class III antiarrhythmic drug E‐4031 from HERG to M‐eag channels
Authors: Herzberg Ian M. , Trudeau Matthew C. , Robertson Gail A. 
Published: September 2004

The gating behaviour and pharmacological sensitivity of HERG are remarkably different from the corresponding properties of M‐eag, a structurally similar member of the Eag family of potassium channels. In contrast to HERG, M‐eag exhibits no apparent inactivation and little rectification, and is insensitive to the class III antiarrhythmic drug E‐4031.
We generated chimeric channels of HERG and M‐eag sequences and made point mutations to identify the region necessary for rapid inactivation in HERG. This region includes the P region and half of the S6 putative transmembrane domain, including sites not previously associated with inactivation and rectification in HERG.
Transfer of a small segment of the HERG polypeptide to M‐eag, consisting largely of the P region and part of the S6 transmembrane domain, is sufficient to confer rapid inactivation and E‐4031 sensitivity to M‐eag. This region differs from the corresponding region in M‐eag by only fifteen residues.
Previous hypotheses that rapid inactivation of HERG channels occurs by a C‐type inactivation mechanism are supported by the parallel effects on rates of HERG inactivation and Shaker C‐type inactivation by a series of mutations at two equivalent sites in the polypeptide sequences.
In addition to sites homologous to those previously described for C‐type inactivation in Shaker, inactivation in HERG involves a residue in the upstream P region not previously associated with C‐type inactivation. Although this site is equivalent to one implicated in P‐type inactivation in Kv2.1 channels, our data are most consistent with a single, C‐type inactivation mechanism.