bluuebunny/crossref_metadata_2025 huggingface dataset:
The routine use of pediatric airway exchange catheter after extubation of adult patients who have undergone maxillofacial or major neck surgery: a clinical observational study
Authors: Dosemeci Levent , Yilmaz Murat , Yegin Arif , Cengiz Melike , Ramazanoglu Atilla
Published: September 2004

Introduction

We conducted the present study to determine the usefulness of routinely inserting a pediatric airway exchange catheter (PAEC) before tracheal extubation of adult patients who had undergone maxillofacial or major neck surgery and have risk factors for difficult reintubation.

Methods

A prospective, observational and clinical study was performed in the 25-bed general intensive care unit of a university hospital. Thirty-six adult patients who underwent maxillofacial or major neck surgery and had risk factors for difficult reintubation were extubated after insertion of the PAEC.

Results

Four of 36 (11.1%) patients required emergency reintubation after 2, 4, 6 and 18 hours after tracheal extubation, respectively. Reintubation of these patients, which was thought to be nearly impossible by direct laryngoscopy, was easily achieved over the PAEC.

Conclusion

The PAEC can be a life-saving device during reintubation of patients with risk factors for difficult reintubation such as laryngeo-pharyngeal oedema due to surgical manipulation or airway obstruction resulting from haematoma and anatomic changes. We therefore suggest the routine use of the PAEC in patients undergoing major maxillofacial or major neck surgery.
Intercompartmental fluid volume shifts during cardiopulmonary bypass measured by A-mode ultrasonography
Authors: Schumacher Jan , Eichler Wolfgang , Heringlake Matthias , Sievers Hans-Hinrich , Klotz Karl-Friedrich
Published: September 2004

To investigate the time course of fluid extravasation during cardiopulmonary bypass (CPB), we measured the peripheral tissue thickness (TT) by A-mode ultra-sound in 34 patients undergoing elective cardiac surgery. TT of the forehead was determined by a handheld A-mode ultrasound device and 10 MHz Transducer at nine defined intervals, from the night before surgery until the first postoperative day.

Mean calculated loss of 1700±40 mL (SEM) water during the fasting period resulted in a significant reduction of TT by 0.28±0.03 mm. From induction to start of CPB, rehydration with 1000 mL of fluid was performed and TT increased to baseline. After 60 min of extracorporal circulation, forehead TT increased significantly by 0.75±0.08 mm and remained unchanged until the end of surgery when the measured fluid gain was 1580±138 mL. At discharge from ICU, negative fluid regimen resulted in a balance of -127±146 mL whereas TT declined significantly to + 0.16±0.09 mm compared to baseline.

Dehydration due to fasting and the marked interstitial fluid extravasation during CPB could be detected by the changes of the peripheral TT. We conclude that parts of the fluid load during CPB are shifted from the intravascular compartment to the interstitial space in a time-dependent manner.
External validation of compliance to perfusion quality indicators
Authors: Dickinson Timothy , Riley Jeffrey , Zabetakis Paul M
Published: September 2004

Purpose: There exists a significant gap between the expected and delivered level of quality received in America’s hospitals. As a result, clinical outcomes of critical services such as coronary artery bypass graft (CABG) surgery have received unparalleled scrutiny. Medical information technology companies like Solucient and insurance carriers such as Blue Cross of California have identified and published a list of hospitals that demonstrate superior quality and patient outcomes for CABG procedures. These ‘benchmark’ programs serve as a reminder that closing the quality gap is possible. Unfortunately, none of these rankings (report cards) provide programs that fail to achieve benchmark status with detailed information on the processes or methods necessary to improve performance.

Method: After identifying hospitals within the Fresenius Medical Care Extracorporeal Alliance (FMCEA) system that were judged as top performers (benchmark programs) by either Solucient (‘100 Top Cardiovascular Hospitals’, Evanston, IL 60201) or Blue Cross of California (‘Centers of Expertise’, Newbury Park, CA 91320), 12 months of continuous collection of CPB-related quality indicator data were analyzed for compliance to the FMCEA evidence-based Quality Indicator Program (QIP). A comparison of compliance to the FMCEA CPB indicators was made between the benchmark FMCEA hospitals and the FMCEA peer group hospitals.

Results: Seven CPB process indicators were compared: 1) lowest sustained mean arterial pressure, 2) lowest sustained cardiac index, 3) lowest sustained mixed venous oxygen saturation, 4) lowest sustained hematocrit, 5) lowest activated clotting time, 6) highest sustained arterial blood temperature and 7) average sodium bicarbonate administered. Analysis of hospitals in the FMCEA system designated by Blue Cross of California as ‘Centers of Expertise’ revealed statistically significantly greater compliance ( p<0.05) in all but one CPB indicator. Hospitals in the FMCEA system designated by Solucient’s ‘100 Top Cardiovascular Hospitals’ listing revealed statistically significantly greater compliance to all but three CPB quality indicators.

Conclusions: Successful compliance with the majority of FMCEA CPB process indicators correlates with external recognition from two report card systems demonstrating superior hospital performance. Analysis of compliance to process indicators may provide useful guidelines to improve the standard of care in CABG surgery in many hospitals.
Management of continuous venous gas emboli during extracorporeal life support utilizing the Kolobow gas trap
Authors: Faulkner Sherry C , Johnson Charles E , Tucker Juan , Schmitz Michael L , Drummond-Webb Jonathan J
Published: September 2004

Extracorporeal life support (ECLS) with a roller pump system uses a closed cardiopulmonary bypass (CPB) circuit not equipped with a venous reservoir. Hence, gas emboli cannot escape the ECLS circuit, predisposing to clot formation, membrane failure and potential gas embolism. Rarely, some patients may develop a continuous release of gas into the venous circulation from multiple sources. Two pediatric ECLS cases are presented with continuous venous gas embolism. A ‘gas trap’ was devised by creating a column of fluid erected vertically on the venous line. This allowed gas to rise within the column, separating it from the ECLS circuit, thus, preventing gas from lodging in the membrane.
Induction and detection of disturbed homeostasis in cardiopulmonary bypass
Authors: de Vroege R , te Meerman F , Eijsman L , Wildevuur W R , Wildevuur Ch RH , van Oeveren W
Published: September 2004

During cardiopulmonary bypass (CPB) haemodynamic alterations, haemostasis and the inflammatory response are the main causes of homeostatic disruption. Even with CPB procedures of short duration, the homeostasis of a patient is disrupted and, in many cases, requires intensive postoperative treatment to re-establish the physiological state of the patient. Although mortality is low, disruption of homeostasis may contribute to increased morbidity, particularly in high-risk patients. Over the past decades, considerable technical improvements in CPB equipment have been made to prevent the development of the systemic inflammatory response syndrome (SIRS). Despite all these improvements, only the inflammatory response, to some extent, has been reduced. The microcirculation is still impaired, as measured by tissue degradation products of various organs, indicating that CPB may still be considered as an unphysiological procedure. The question is, therefore, whether we can detect the pathophysiological consequences of CPB in each individual patient with valid bedside markers, and whether we can relate this to determinant factors in the CPB procedure in order to assist the perfusionist in improving the adequacy of CPB. The use of these markers could play a pivotal role in decision making by providing an immediate feedback on the determinant quality of perfusion. Therefore, we suggest validating the proposed markers in a nomogram to optimize not only the CPB procedure, but also the patient’s safety.
Ex vivo evaluation of a new neonatal/infant oxygenator: comparison of the Terumo CAPIOX® Baby RX with Dideco Lilliput 1 and Polystan Safe Micro in the piglet model
Authors: Dubois J , Jamaer L , Mees U , Pauwels J-L , Briers F , Lehaen J , Hendrikx M
Published: September 2004

Objective: A newly developed neonatal and infant oxygenator with a nonheparin biocompatible polymer coating, low priming volume (43 mL), high oxygen transfer, wide operating range (<1.5 L/min) and low pressure drop represents a promising solution for cardiac surgery in neonates and infants. We compared the new CAPIOX® Baby RX, Terumo (BRX) with two commonly used neonatal oxygenators: Dideco Lilliput 1 (DL1) and Polystan Safe Micro (PSM) in a piglet model.

Methods: Fifteen piglets (5.6±1.3 kg) were placed on standardized cardiopulmonary bypass (CPB) for 6 hours using one of the three oxygenators ( n = 5 in each group). After 120 min, the system was cooled to 25°C for 60 min and then returned to normothermia. Arterial and venous blood gas data and temperature were recorded continuously by a CDI500 System (Terumo). Pressure drop, FiO2 and gas flow were recorded. Blood samples were taken before CBP, after 10 min, before and after cooling, and at the end. Total blood counts, thrombin-antithrombin complex and plasma-free haemoglobin (PfHb) were measured.

Results: All oxygenators showed acceptable performance for the duration of CPB. The BRX had lower mean gas flow (0.33±0.05 L/min) and FiO2 (0.43± 0.02%) throughout CPB than the DL1 (1.14±0.25 L/min, p = 0.006 and 0.60±0.02%, p = 0.009, respectively) or the PSM (1.47±0.87 L/min and 0.54±0.08%, p = ns). Pressure drop in the BRX group ranged from 12 to 22 mmHg. This was significantly lower than in the DL1 group (39-65 mmHg, p = 0.005). In the PSM group, values ranged between 24 and 33 mmHg (p = ns). The increase in PfHb at six hours was significantly lower in the BRX (11.3±4.2 ng/dL) versus the DL1 (42.2±6.1 ng/dL, p = 0.004) and the PSM (56.7±15.5 ng/dL, p = 0.045).

Conclusions: The BRX is as safe as the DL1 and the PSM, with superior performance in pressure drop, efficient blood gas management and lower haemolysis. The BRX exhibited the lowest prime, hold-up volume and breakthrough time.
Argatroban as an alternative to heparin in extracorporeal membrane oxygenation circuits
Authors: Young Guy , Yonekawa Karyn E , Nakagawa Peggy , Nugent Diane J
Published: September 2004

We investigated the anticoagulant effects of argatroban, a direct thrombin inhibitor, versus heparin in extracorporeal membrane oxygenation (ECMO) circuits. Three sham circuits were prepared according to our hospital’s standard practice and run for six hours simultaneously. Two circuits were anticoagulated with argatroban (one with heparin in the wet prime and one without). One circuit had heparin in the initial prime and was then anticoagulated with heparin. We measured thrombin generation (prothrombin fragment 1+2, D-dimer and thrombin-antithrombin complexes), activated clotting times (ACTs) and partial thromboplastin times (aPTTs), and monitored thrombus formation using thromboelastography. ACTs were >1000 s in each circuit throughout assessment. No clot initiation was detected by thromboelastography. Thrombin generation was decreased in circuits anticoagulated with argatroban versus heparin, despite aPTTs being less prolonged. These results suggest that argatroban may be more efficacious than heparin for anticoagulation in ECMO. Additional studies are warranted to further evaluate argatroban in this setting.
Refractory ventricular fibrillation in accidental hypothermia: salvage with cardiopulmonary bypass
Authors: Mulpur Anil Kumar , Mirsadraee Saeed , Hassan Taj B , McKeague Helena , Kaul Pankaj
Published: September 2004

A 20-year old woman presented with prolonged refractory ventricular fibrillation and pulmonary oedema following hypothermia while she was under self-administered heroin in an attempt to commit suicide. She was successfully resuscitated with cardiopulmonary bypass for core rewarming and internal defibrillation.
A novel extracorporeal kidney perfusion system: a concept model
Authors: Szajer Michael , Shah Gaurang , Kittur Dilip , Searles Bruce , Li Lu , Bruch David , Darling Edward
Published: September 2004

The number of patients awaiting kidney transplantation has more than doubled in the past decade while the number of available donor organs has seen only a modest increase, leading to a critical shortage of organs. In response to this extreme shortage, the criteria for accepting organs have been modified to include marginal donors such as non-heart beating donors (NHBD). In these kidneys, determining viability is important for success of transplantation. Therefore, a study was undertaken to develop a system that would allow the extra-corporeal assessment of function and compatibility of the donor organ before the patient is exposed to the risks associated with surgery.

Following bilateral nephrectomy, the kidneys of 10 pigs (~30 kg) were connected to a commercially available hypothermic pulsatile kidney perfusion apparatus. This system was modified to allow for normothermic pulsatile renal perfusion using the potential recipient’s blood, via vascular access. These kidneys were perfused with the animal’s blood for a minimum of two hours while various parameters were monitored. Perfusion pressures were kept between 60 and 90 mmHg, which correlated to flows between 70 and 150 mL/min. A decrease in perfusion pressure with a concomitant rise in flow over the two-hour period served as a good predictor of a viable and compatible graft. The modified kidney preservation system allows the normothermic, pulsatile extracorporeal perfusion of donor kidneys with the ability to monitor resistance to flow and urine production. This model also allows observation of the kidney for signs of hyperacute rejection. Further research needs to be conducted in order to determine if the system represents a methodology to increase the pool of available donor organs.
Quantitative haemodynamic evaluation of aortic cannulas
Authors: Andersen Mia N , Ringgaard Steffen , Hasenkam J Michael , Nygaard Hans
Published: September 2004

We have designed a new type of aortic cannula for extracorporeal circulation which we hypothesize has superior haemodynamic characteristics compared with existing types. The aim of the study was to perform a quantitative evaluation of the haemodynamic performance of commercially available aortic cannulas against our new design. Six existing cannulas and two self-designed, modified DLP cannulas were investigated. Pressure drop, peak velocity and wall thickness were obtained from in vitro experiments. Pressure drop and turbulent stresses were obtained by in vivo experiments. At 5 L/min the pressure drops of the new design were 18 - 25 mmHg in vitro and 20 mmHg in vivo compared with 25 - 92 mmHg in vitro and 28 - 90 mmHg in vivo for the six commercially available cannulas. Turbulent stresses of the new design varied between 25 and 50 N/m2 in vivo compared with 125 - 500N/m2. Both in vivo and in vitro results showed a clear haemodynamic superiority of the new cannula-tip design compared with all existing types.
Mixture modelling for cluster analysis
Authors: McLachlan G J , Chang S U
Published: September 2004

Cluster analysis via a finite mixture model approach is considered. With this approach to clustering, the data can be partitioned into a specified number of clusters g by first fitting a mixture model with g components. An outright clustering of the data is then obtained by assigning an observation to the component to which it has the highest estimated posterior probability of belonging; that is, the ith cluster consists of those observations assigned to the ith component ( i = 1,..., g). The focus is on the use of mixtures of normal components for the cluster analysis of data that can be regarded as being continuous. But attention is also given to the case of mixed data, where the observations consist of both continuous and discrete variables.
Two-mode clustering methods: astructuredoverview
Authors: Van Mechelen Iven , Bock Hans-Hermann , De Boeck Paul
Published: September 2004

In this paper we present a structured overview of methods for two-mode clustering, that is, methods that provide a simultaneous clustering of the rows and columns of a rectangular data matrix. Key structuring principles include the nature of row, column and data clusters and the type of model structure or associated loss function. We illustrate with analyses of symptom data on archetypal psychiatric patients.
Fuzzy set analyses of genetic determinants of health and disability status
Authors: Manton Kenneth G , Gu Xiliang , Huang Hai , Kovtun Mikhail
Published: September 2004

Analyses of complex genotype-phenotype relations require new statistical procedures because of the potentially high dimensionability of those relations which are expressed with both measurement error and stochasticity in the correlation function. We propose modifying a multivariate procedure called grade of membership (GoM) analysis to deal with the special problems of such analyses. In doing so, we make clear some special features of the GoM model for multivariate analysis of high dimensional, discrete data. This is illustrated for apolipoprotein E (APOE) assessments made on 1805 people in the 1999 National Long Term Care Survey. A number of interesting relations with APOE polymorphism were found where disability profiles were more predictive than specific diagnoses because they implicitly contained information on chronicity and severity of disease processes.
Modulatory effect of Morus indica against two-stage skin carcinogenesis in Swiss albino mice: possible mechanism by inhibiting aryl hydrocarbon hydroxylase
Authors: Prasad Lakshmi , Khan Tajdar H , Sehrawat Anuradha , Sultana Sarwat
Published: September 2004

The modulatory effect of the methanolic extract of Morus indica on 12-O-tetradecanoyl-phorbol-13-acetate (TPA) induced oxidative stress and 7,12-dimethylbenz(a)anthracene induced and croton oil (0.5% per mouse/0.2 mL acetone, v/v) promoted skin tumourigenesis in Swiss albino mice was studied. The efficacy of the M. indica extract was also evaluated in-vitro by studying the inhibition of the activity and level of aryl hydrocarbon hydroxylase, cytochrome P450, DNA sugar damage in calf thymus DNA and Fe++/ascorbate-induced lipid peroxidation in microsomes of mice. Significant increases in the activity of antioxidant enzymes (P < 0.001) and a concomitant decrease (P < 0.001) in the cutaneous malondialdehyde level were observed at three doses of plant extract (2.5, 5.0 and 7.5 mg kg−1). Application of M. indica 1 h before each application of croton oil showed inhibitory effects on tumour promotion in terms of a reduction in the number of tumours/mouse and percentage of mice with tumours. It was also accompanied by an extension of the tumour latency period. TPA, which resulted in a rapid and transient stimulation of mouse epidermal ornithine decarboxylase activity (P < 0.001), was inhibited dose dependently by pre-treatment with M. indica extract (P < 0.001). The results suggest that M. indica extract may be useful as a therapeutic agent for cancer control as it blocks or suppresses events associated with chemical carcinogenesis.
Evaluation of in-vivo topical anti-inflammatory activity of indometacin from liposomal vesicles
Authors: Puglia Carmelo , Trombetta Domenico , Venuti Vincenza , Saija Antonella , Bonina Francesco
Published: September 2004

The aim of this study was to evaluate the in-vivo drug release profile of indometacin-loaded liposomes into the skin. Large unilamellar vesicles (LUVs), composed of dipalmitoyl-L-α-phosphatidylcholine and cholesterol (9:1), were obtained using the extrusion method and then incorporated in hydrogels (LUV-A and LUV-B). The delivery of indometacin from the liposomal system was evaluated by determining its in-vivo local anti-inflammatory activity after cutaneous application of liposomal gel formulations; the anti-inflammatory activity is directly proportional to the amount of drug that actually crosses the skin. UVB-induced erythema on healthy human volunteers was chosen as the inflammatory model and the extent of erythema was monitored by the non-invasive technique of reflectance spectrophotometry. The results showed that LUV dispersions containing indometacin provided a high percentage of entrapped drug (∼84%). Furthermore, in-vivo findings revealed that the anti-inflammatory effect was more prolonged when indometacin was delivered from a liposomal gel formulation rather than from a gel formulation without liposomes. In particular, the indometacin-loaded gel formulation LUV-A showed a sustained effect, probably related to an interaction between LUV lipids and stratum corneum lipid structure. This interaction produces a depot in the stratum corneum that ensures sustained release of the drug to deeper skin layers.
An ocular drug delivery system containing zinc diethyldithiocarbamate and HPβCD inclusion complex - corneal permeability, anti-cataract effects and mechanism studies
Authors: Wang Siling , Li Dexin , Ito Yoshimasa , Liu Xia , Zhang Jinghai , Wu Chunfu
Published: September 2004

Our purpose was to study the formulation and anti-cataract effects of aqueous eye drops containing a high concentration of zinc diethyldithiocarbamate (Zn-DDC). A possible mechanism of the anti-cataract effect of Zn-DDC was also studied. Zn-DDC and hydroxypropyl-β-cyclodextrin (HPβCD) inclusion complex (Zn-DDC/HPβCD) was studied using the saturation solution method and characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (IR). Suitable formulations for Zn-DDC eye drops were established by means of in-vitro trans-corneal penetration experiments. The anti-cataract effect of the selected formulation was demonstrated by the delay in lens opacity development in hereditary shumuya cataract rats (SCRs). Semiquantitative reverse transcription polymerase chain reaction (RT-PCR) was performed to study the effect of diethyldithiocarbamate (DDC), a metabolite of Zn-DDC, on the transcription inducible nitric oxide synthase (iNOS) mRNA in human lens epithelial cells (HLEC). In the presence of 22% (w/v) HPβCD, the solubility of Zn-DDC in water (0.2 mm) was increased almost 850 fold (to 17 mm), by the formation of Zn-DDC/HPβCD. The stoichiometry of Zn-DDC inclusion was 1:1. The Zn-DDC/HPβCD stability constant, K(s) (1:1) was estimated to be 3453 m−1. The ophthalmic preparation containing 0.1% HPMC and 0.1% poloxamer 188 (P188) exhibited better permeability than the others in-vitro, and significantly delayed cataract formation in SCRs compared with non-treated SCRs. DDC inhibits the transcription of iNOS mRNA in HLEC. We concluded that this drug delivery system increases both the drug solubility in aqueous eye drops and the permeability of drug through the rabbit cornea, by the formation of a drug-cyclodextrin inclusion complex and the addition of polymers and penetration enhancers. The preparation effectively prevented the development of cataracts in SCRs. DDC, the metabolite of Zn-DDC, may be one of the factors in the prevention of cataract formation because it inhibits the transcription of iNOS mRNA.
The Coevolution of Trust, Control, and Learning in Joint Ventures
Authors: Inkpen Andrew C. , Currall Steven C.
Published: September 2004

This article examines the evolution of trust, control, and learning in a joint venture relationship. Using a coevolutionary approach, we develop a framework that shows how initial joint venture conditions give way to evolved conditions as joint venture partners develop an understanding of each other and adjust the collaborative process. We explore the relationship between trust and control in joint ventures and identify how these two critical concepts impact joint venture processes. We argue that trust, along with partner collaborative objectives, creates the initial climate that shapes partner interactions. In turn, these interactions lead to subsequent decisions about the nature of controls. We then examine linkages between alliance learning and the trust and control concepts, and argue that learning processes are central to evolving joint venture dynamics. Once the joint venture is formed, and if the initial conditions support continued collaboration, then learning processes will be central to evolving alliance dynamics. As initial conditions give way to evolved conditions, learning and trust will coevolve and impact decisions about control. Propositions linking the concepts are provided as guides for future empirical research.
A Test of the Individual Action Model for Organizational Information Commons
Authors: Fulk Janet , Heino Rebecca , Flanagin Andrew J. , Monge Peter R. , Bar François
Published: September 2004

This research elaborated and empirically tested the individual action component of the collective action model as applied to individual contributions to organizational information commons. The model extended prior theory and research by making six elaborations on the classic collective action model based on unique characteristics of information goods compared to material collective goods. The structural equation model was tested via LISREL analyses of data provided by 781 respondents in three high-tech firms who had access to corporate intranets as shared information goods. The results were highly similar across organizations and indicated that (a) level of production, information retrieval, and cost predicted the perceived value of information, (b) information value and cost predicted gain, and (c) information retrieval and gain predicted the level of individual contributions to the commons.
Firm- and Country-Level Trade-offs and Contingencies in the Evaluation of Foreign Investment: The Semiconductor Industry, 1994–2002
Authors: Henisz Witold J. , Macher Jeffrey T.
Published: September 2004

This paper examines the joint impact of firm- and country-level factors on the international plant location decisions of semiconductor firms from 1994–2002. We find that these factors interact to influence the location decisions of firms investing abroad in a given host country. Firms with more advanced technological capabilities are more likely to make investments in countries with greater technological sophistication but not in politically hazardous countries where they face greater expropriation hazards. Firms with less-advanced technology are more willing to accept a trade-off between country-level political hazards and technological sophistication. Firms also trade off own- versus other-firm experience as sources of critical knowledge regarding the foreign investment environment.
Transferring, Translating, and Transforming: An Integrative Framework for Managing Knowledge Across Boundaries
Authors: Carlile Paul R.
Published: September 2004

The paper examines managing knowledge across boundaries in settings where innovation is desired. Innovation is a useful context because it allows us to explore the negative consequences of the path-dependent nature of knowledge. A framework is developed that describes three progressively complex boundaries—syntactic, semantic, and pragmatic—and three progressively complex processes—transfer, translation, and transformation. The framework is used to specify the practical and political mismatches that occur when innovation is desired and how this relates to the common knowledge that actors use to share and assess each other's domain-specific knowledge. The development and use of a collaborative engineering tool in the early stages of a vehicle's development is presented to illustrate the conceptual and prescriptive value of the framework. The implication of this framework on key topics in the organization theory and strategy literatures is then discussed.
Organizational Emergence: The Origin and Transformation of Branson, Missouri's Musical Theaters
Authors: Chiles Todd H. , Meyer Alan D. , Hench Thomas J.
Published: September 2004

We draw on complexity theory to explain the emergence of a new organizational collective, and we provide a much-needed empirical test of the theory at the collective level of analysis. Taking a case study approach, we use four dynamics of emergence posited by complexity theory's dissipative structures model—fluctuation, positive feedback, stabilization, and recombination—to explain how a collective of live musical performance theaters in Branson, Missouri, came into being and periodically transformed itself over a 100-year period. Our findings suggest a strong match between the theoretical perspective employed and the empirical processes uncovered, empirically validating the model at the collective level. The study demonstrates the value of conceptualizing evolution in terms of emergence, highlighting distinctions between the nascent complexity approach to evolution and the neo-Darwinian evolutionary approach that has dominated the theoretical conversation in organization science for the past generation. Our findings complement the insights of the dominant theoretical perspectives in organization theory, providing a more comprehensive understanding of organizational evolution by directly addressing the heretofore intractable phenomenon of emergence.
When and How Trustworthiness Matters: Knowledge Transfer and the Moderating Effect of Causal Ambiguity
Authors: Szulanski Gabriel , Cappetta Rossella , Jensen Robert J.
Published: September 2004

The recognition that better use of existing internal knowledge could enhance survival chances of organizations has spawned substantial interest in the transferability of routinized, experiential learning to additional settings within the organization. Previous research has established that trustworthiness of the source enhances such knowledge transfer. More recent work, however, suggests that this may not always be the case. Yet, little systematic attention has been paid to moderating conditions. The major purpose of this paper is to identify a moderator, causal ambiguity, which delineates the conditions as to when and how a recipient's perception of the trustworthiness of a source affects the effectiveness of the transfer of organizational practices.
Contextualizing Patterns of Work Group Interaction: Toward a Nested Theory of Structuration
Authors: Perlow Leslie A. , Gittell Jody Hoffer , Katz Nancy
Published: September 2004

The focus of this article is the patterns of interaction that arise within work groups, and how organizational and institutional factors play a role in shaping these patterns. Based on an ethnographic study of groups across three national contexts, we describe the variation in patterns of interaction that we observed. We further suggest how different patterns of interaction form mutually reinforcing systems with aspects of the organizational context. In addition, we suggest how these mutually reinforcing systems are perpetuated by aspects of the broader institutional context. Our findings point toward a nested theory of structuration, expanding structuration theory to multiple levels simultaneously. In turn our findings have theoretical and practical implications for better understanding and managing interaction patterns among group members.
HPLC Retention Time as a Diagnostic Tool for Hemoglobin Variants and Hemoglobinopathies: A Study of 60000 Samples in a Clinical Diagnostic Laboratory
Authors: Joutovsky Alla , Hadzi-Nesic Joan , Nardi Michael A
Published: September 2004

Background: Previous evaluations of HPLC as a tool for detection of hemoglobin variants have done so within newborn-screening programs and/or by use of stored samples. We describe a 32-month prospective study in a clinical diagnostic laboratory in which we evaluated the imprecision of HPLC retention times and determined the retention times for hemoglobin variants seen in a multiethnic setting.

Methods: We analyzed all samples on the Bio-Rad Variant II HPLC system. For normal hemoglobin fractions and hemoglobin variants, we recorded and analyzed their retention times, their proportion of the total hemoglobin (%), and the peak characteristics. We compared the imprecision of retention time with the imprecision of retention time normalized to the retention time of hemoglobin A0 (HbA0) and to the retention time of HbA2. Alkaline and acid hemoglobin electrophoresis, and in certain cases globin chain electrophoresis, isoelectric focusing, and DNA analysis, were performed to document the identities of the hemoglobin variants.

Results: The mean (SD) imprecision (CV) of the retention time was 1.0 (0.7)% with no statistical difference compared with the imprecision for normalized retention times. Among 60293 samples tested, we encountered 34 unique hemoglobin variants and 2 tetramers. Eighteen variants and 2 tetramers could be identified solely by retention time and 3 variants by retention time and proportion of total hemoglobin. Four variants could be identified by retention time and peak characteristics and eight variants by retention time and electrophoretic mobility. One variant (HbNew York) was missed on HPLC. Retention time on HPLC was superior to electrophoresis for the differentiation and identification of six members of the HbJ family, four members of the HbD family, and three variants with electrophoretic mobilities identical or similar to that of HbC. Six variants with electrophoretic mobilities identical or similar to that of HbS could be differentiated and identified by retention time and proportion of total hemoglobin. HPLC detected two variants (HbTy Gard and HbTwin Peaks) missed on electrophoresis.

Conclusions: The retention time on HPLC is reliable, reproducible, and in many cases superior to conventional hemoglobin electrophoresis for the detection and identification of hemoglobin variants. Confirmatory testing by electrophoresis can be eliminated in the majority of cases by use of retention time, proportion of total hemoglobin, and peak characteristics of HPLC.
Hybridization Isotherms of DNA Microarrays and the Quantification of Mutation Studies
Authors: Halperin Avraham , Buhot Arnaud , Zhulina Ekaterina B
Published: September 2004

Background: Diagnostic DNA arrays for detection of point mutations as markers for cancer usually function in the presence of a large excess of wild-type DNA. This excess can give rise to false positives as a result of competitive hybridization of the wild-type target at the mutation spot. Analysis of the DNA array data is typically qualitative, aimed at establishing the presence or absence of a particular point mutation. Our theoretical approach yields methods for quantifying the analysis to obtain the ratio of concentrations of mutated and wild-type DNA.

Method: The theory is formulated in terms of the hybridization isotherms relating the hybridization fraction at the spot to the composition of the sample solutions at thermodynamic equilibrium. It focuses on samples containing an excess of single-stranded DNA and on DNA arrays with a low surface density of probes. The hybridization equilibrium constants can be obtained by the nearest-neighbor method.

Results: Two approaches allow acquisition of quantitative results from the DNA array data. In one, the signal of the mutation spot is compared with that of the wild-type spot. The implementation requires knowledge of the saturation intensity of the two spots. The second approach requires comparison of the intensity of the mutation spot at two different temperatures. In this case, knowledge of the saturation signal is not always necessary.

Conclusions: DNA arrays can be used to obtain quantitative results on the concentration ratio of mutated DNA to wild-type DNA in studies of somatic point mutations.
Transverse Young's Moduli and Cell Shapes in Coniferous Early Wood
Authors: Watanabe Ugai , Fujita Minoru , Norimoto Misato
Published: September 2004

The relationship between transverse Young's moduli and cell shapes in coniferous early wood was investigated
using cell models constructed by two dimensional power spectrum analysis. The calculated values
of tangential Young's modulus qualitatively explained the relationship between experimental values
and density as well as the difference in experimental values among species. The calculated values of radial
Young's modulus for the species having hexagonal cells agreed well with the experimental values,
whereas, for the species having square cells, the calculated values were much larger than the experimental
values. This result was ascribed to the fact that the bending moment on the radial cell wall of
square cell models was calculated to be small. It is suggested that the asymmetrical shape of real wood
cells or the behavior of nodes during ell deformation is an important factor in the mechanism of linear
elastic deformation of wood cells.
Cytochemical Localization of Hydrogen Peroxide Production during Wood Decay by Brown-Rot Fungi Tyromyces palustris and Coniophora puteana
Authors: Kim Yoon Soo , Wi Seung Gon , Lee Kwang Ho , Singh Adya P.
Published: September 2004

It is not definitively known whether or not the production of extracellular hydrogen peroxide (H2O2) is
a universal characteristic of brown-rot fungi. Cytochemical localization of H2O2 was tested in two
brown-rot fungi, Tyromyces palustris and Coniophora puteana, by staining with cerium chloride. Transmission
electron microscopy (TEM) showed the deposition of cerium perhydroxide within the fungal
hyphae as well as wood cell walls affected by brown-rot fungi. TEM work indicated that extracellular
H2O2 was present in brown-rot fungi and that H2O2 from brown-rot fungi diffused into the wood cell
walls in the early stages of decay. The present work strongly suggests that H2O2 plays an important role
in the early degradation of cellulose by brown-rot fungi. The usefulness of this technique for localizing
H2O2 at high resolution with minimal nonspecific deposition is also discussed.
The Further Chemistry of Ellagic Acid II. Ellagic Acid and Water-Soluble Ellagates as Metal Precipitants
Authors: Przewloka S.R. , Shearer B.J.
Published: September 2004

Preparations of the previously unreported, water-soluble, tetraguanidinium, tetracholine and tetrakisbenzyltrimethylammonium
ellagates are outlined. Ellagic acid and these water-soluble salts remove
Mg2+, Ca2+ and Mn2+ ions from dilute aqueous solutions at pH greater than 7. The salts also remove Fe2+,
Fe3+, Co2+ and Cu2+ between pH 3 and pH 6. At pH 1 the water-soluble ellagates underwent hydrolysis,
resulting in the precipitation of free ellagic acid in preference to the formation of metal-ellagate complexes.
These trends were also observed when mixtures of metal ions were applied.
Investigation on Fossil Barks from an Arctic Canadian Site Constituted by a Multiple Level Tertiary Fossil Forest 45 Million Years Old
Authors: Staccioli Giuseppe , Meli Andrea , Fratini Fabio
Published: September 2004

Barks from the litters of a multiple level Tertiary fossil forest from the Canadian Arctic were chemically
examined and compared with coeval Arctic fossil woods. Degradation and diagenesis of the polysaccharides
similarly occurred in barks and woods. However, unlike the fossil woods, the loss of polysaccharides
led to materials exhibiting a marked cation exchange capacity, which is comparable to what
is found for humus, the final product of diagenesis of the forest litter. Dichloromethane extracts from
the barks invariably showed the presence of n-alkanes from C14 to C30, and terpenes such as cadalene,
calamenene, fichtelite, sandaracopimarane, abietatriene, simonellite, diaromatic totarane, ferruginol,
dehydroferruginol, and sugiol. The presence of phenol-diterpenes and/or diaromatic totarane was related
to species belonging to Cupressaceae, Taxodiaceae and Podocarpaceae, in agreement with the recovery
of trunks of metasequoia in some forest levels.
Moisture Content and Extractive Materials in Maritime Pine Wood by Low Field 1H NMR
Authors: Labbé Nicole , Jéso Bernard De , Lartigue Jean-Claude , Daudé Gérard , Pétraud Michel , Ratier Max
Published: September 2004

The low field1H NMR relaxometry technique has been shown to be effective in determining the qualitative and quantitative moisture content and the water state distribution in maritime pine wood (Pinus pinasterAit). Further investigations on extractive materials in resin-rich samples evinced the presence of oleoresin components, which may disturb adhesion on pine wood boards.
Ozone Oxidation and Structural Features of an Almond Shell Lignin Remaining after Furfural Manufacture
Authors: Quesada J. , Teffo-Bertaud F. , Croué J.P. , Rubio M.
Published: September 2004

Wastes from industrial processes which use lignocellulosic materials as raw material are an interesting
source of chemicals since they can be transformed into products of high added value. In the process
described here, ozone was used to produce oxyaromatics from a lignin-rich industrial waste resulting
from the production of furfural from almond shells. Ozonation, thioacidolysis and mild alkaline hydrolysis
were used to determine some structural features of the raw and acid-hydrolyzed almond shell lignins.
During ozone treatment of the different lignin solutions the following compounds were identified: glycolic,
oxalic, malonic, glyceric (trace), malic, p-hydroxybenzoic and vanillic acids, p-hydroxybenzaldehyde,
vanillin, syringaldehyde and hydroquinone. The aromatic aldehydes passed through a production
maximum during the first few minutes of the reaction, while glycolic and oxalic acid (the main aliphatic
acids) yields increased throughout the treatment. Raw almond shell lignin had a typical hardwood
composition [made up of guaiacyl (G) and syringyl (S) phenylpropane units] and few β-O-4 structures.
Acid-hydrolyzed almond shell lignins had a more condensed structure than the above. The S/G ratio
obtained by ozonation was slightly lower than that obtained by thioacidolysis, with the (S/G)Ozonation/(S/G)Thioacidolysis ratio ranging from 0.52 to 0.70. The almond shell lignin-polysaccharide complex did
not contain any cell wall-esterified p-hydroxycinnamic acid (p-coumaric and ferulic acids).
FTIR Microscopy and Ultrastructural Investigation of Silylated Solid Wood
Authors: Zollfrank Cordt , Wegener Gerd
Published: September 2004

The reaction of two silylating agents (TMSIM, TMS-acetamide) on softwood (white fir) and hardwood
(beech) is examined. As proved by means of FTIR microscopy, silylation takes place at the outer surface
as well as the inner surface. The FTIR spectroscopical features of both softwood and hardwood remain
unchanged. Scanning electron microscopy provides additional evidence that the inner surface is also
successfully silylated. Furthermore, the anatomical characteristics of the silylated wood species are not
changed. No inorganic elements except silicon could be detected in the EDX-analysis. By means of
transmission electron microscopy the reaction site was determined to be on the lumen-faced side of the
cell wall. Half of the S2 wall appears to be silylated.
Nondestructive Analysis of Lignin Structure by NMR Spectroscopy of Specifically 13C-Enriched Lignins. Part 1. Solid State Study of Ginkgo Wood
Authors: Terashima Noritsugu , Hafrén Jonas , Westermark Ulla , VanderHart D. L.
Published: September 2004

Guaiacyl-type lignin is the major component of ginkgo lignin. Specific13c-enrichment of α, β and γ-carbons of the guaiacylpropane side chains was achieved by administration of coniferin-[α13C], coniferin-[β-13C] and coniferin-[γ13C], respectively, to growing stems of ginkgo trees. Unenriched coniferin was administered as a control. The xylem tissues containing specifically13C-enriched lignins or unenriched lignin were subjected to analysis by solid state NMR. Subtraction of the spectrum of tissue containing unenriched lignin from the spectra of tissues containing13C-enriched lignins gave difference spectra exclusively assigned to the enriched side chain carbons of intact protolignin in the cell walls. From the signal intensities determined under quantitative conditions and an estimate of corresponding standard uncertainties, the percentage ranges of the major inter-unit lignin bonds originating from the β-carbon of the coniferin precursor were estimated to be: β-O-4/α-O-R (R = H, polysaccharides or lignols) including β-OH, 53% to 57%; combined β-5, β-β and β-1, 32% to 36%; coniferaldehyde end groups, 2% to 4%; and coniferyl alcohol end groups, 4% to 6%.
Effect of High-Temperature Defibration on the Chemical Structure of Hardwood
Authors: Widsten P. , Laine J.E. , Qvintus-Leino P. , Tuominen S.
Published: September 2004

The present paper aims at elucidating the effect of high-temperature defibration at different temperatures
on the bulk and surface chemical properties of defibrated birch, aspen and eucalypt. The results indicate
that defibration of these hardwoods results in partial depolymerization of fiber lignin via (homolytic)
cleavage of interunit alkyl-aryl (β-O-4) ether bonds. This increases the phenolic hydroxyl content and
produces relatively stable (phenoxy) radicals. Syringyl-type lignin is more extensively depolymerized
than guaiacyl-type lignin. Defibration generates water-extractable material, which is enriched in hemicellulose-derived carbohydrates and has a substantial content of aromatic compounds rich in phenolic
hydroxyl groups. The amount of water-extract and the extent of lignin interunit ether bond cleavage
increase with an increase in defibration temperature. The differences between various hardwood species
in this respect are small. The surface chemical composition of the fibers differs considerably from their
bulk composition, but is not significantly influenced by variations in defibration temperature. Lipophilic
extractives cover a large portion of the fiber surface, while the lignin content of lipophilic extractives-free
fiber surfaces is 2–3 times as high as the bulk lignin content of the fibers.
Totally Chlorine Free Bleaching of Eucalyptus globulus Dissolving Pulps Delignified with Peroxyformic Acid and Formic Acid
Authors: Abad S. , Saake B. , Puls J. , Parajó J. C.
Published: September 2004

Eucalyptus globulus wood samples were delignified in two-stage treatments carried out in media made
up of formic acid, water and hydrogen peroxide under selected operational conditions. The pulps were
subjected to Totally Chlorine Free (TCF) bleaching sequences. Alkaline treatments, oxygen delignification,
ozone stages and treatments with peroxyacids were assayed in order to reach the target values for
dissolving pulps. Under the best conditions, a fully bleached pulp (91.6% ISO brightness) with SCAN
viscosity of 649 ml/g and favourable molar mass distribution was obtained.
Effect of the α- and γ-Hydroxyls on the Alkaline Hydrolysis Rate of Nonphenolic β-0-4 Lignin Diastereomers
Authors: Criss Dexter L. , Elder Thomas , Fisher Thomas H. , Schultz Tor P.
Published: September 2004

Nonphenolic β-0-4 erythro and threo lignin model diastereomers with various γ-groups (CH3, CH2-O-CH3,
and CH2OH) and Cα-substituents (OH, OCH3) were synthesized, and the alkaline hydrolysis rates
and activation parameters determined. In addition, two of the diastereomer pairs were computationally
modeled and the thermodynamic values for the ionization of the α- or γ-hydroxyl, and subsequent displacement
of the phenolate group to form an epoxide intermediate, were determined. The results suggest
that the erythro γ-hydroxyl may participate in the hydrolysis to a significant extent, which results in a
relatively high erythro/threo rate ratio for the α,γ-di-OH isomers. The influence of the erythro γ-hydroxyl
on the hydrolysis rate may be due to the relatively favorable stability of the erythro γ-oxyanion. The
electronic effect of the g-substituent appears to influence how fast the α-hydroxyl displaces the phenoxyl.
We had previously suggested that the γ-substituent sterically inhibits hydrolysis of the threo isomer, and
computational modeling confirmed this.