bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of ultrasound and computed tomography for the diagnosis of a squamous cell carcinoma of the oesophago-cardial region of the stomach in a rhesus monkey
Authors: Schmitz H. Cristina , Weishaupt D. , Borel N. , Padberg B. , Bfirki K.
Published: January 2004

A 5-year-old female rhesus macaque ( Macaca mulatta) suddenly began suffering from anorexia, dysphagia, vomiting, diarrhoea, and anaemia. Clinical examination and conventional radiography were uneventful. Additionally an ultrasound (US) and computed tomography (CT) were performed which revealed a large tumorous mass in the upper abdomen and a lung metastasis. Using sonographic guidance, a biopsy of the abdominal masse was taken. Histopathological analysis revealed the diagnosis of a squamous cell carcinoma. At autopsy, an advanced gastric carcinoma, which originated from the cardia, was found with infiltration of the retroperitoneum, and metastatic involvement of the mesenterial lymph nodes as well as metastasis in the lung parenchyma. This case illustrates the usefulness of modern non-invasive imaging techniques, including US and CT, in enabling a quick and accurate diagnosis in laboratory animals.
McGriff Treading Company Implements Service Contracts with Shared Savings
Authors: Yadav Prashant , Miller David M. , Schmidt Charles P. , Drake Randy
Published: January 2004

Costs related to tires are about three percent of the operating costs of a transport fleet. Fleet operators have been trying to reduce these costs by extending the tires’ useful life and by increasing their use of retreaded tires. A program to reduce tire wear can pay off only if the fleet operator and the retreader cooperate. However, the typical contract between the two leads to conflicting incentives. We devised a service contract with shared savings and cautiously chosen parameters for McGriff Treading Company, Inc., that better aligns the incentives for reducing tire costs. Apart from the optimal choice of contract parameters, managerial performance metrics and information technology systems to monitor and track costs were the key factors in the company's transition from a product to a service company. McGriff Treading now successfully uses such contracts for its intermodal and trucking clients.
Reconfiguring a Remanufacturing Line at Visteon, Mexico
Authors: Kekre Sunder , Rao Uday S. , Swaminathan Jayashankar M. , Zhang Jun
Published: January 2004

Visteon's remanufacturing facility in Lamosa, Mexico was plagued with heavy fluctuations of supply and demand, leading to periods of severe capacity shortage. Management asked us to assess options for improving capacity. We developed a simulation-based line-configuration model that simultaneously considers line balancing and line length (number of production stations) to maximize the remanufacturing system's effective throughput. We computationally analyzed the effect of processing-time variability on line-reconfiguration decisions, the effect of correlated task-processing times on throughput, and the marginal benefits of using dynamic line balancing. Based on the data we collected, we made recommendations for reconfiguring Visteon's remanufacturing line. Management successfully implemented these changes, increased asset utilization, and reduced its planned new investments in capital equipment.
Integrating Closed-Loop Supply Chains and Spare-Parts Management at IBM
Authors: Fleischmann Moritz , van Nunen Jo A. E. E. , Gräve Ben
Published: January 2004

IBM is among the pioneers recognizing the benefits of closed-loop supply chains that integrate product returns into business operations. We worked on a project exploiting product returns as a source of spare parts. Key decisions concern what recovery opportunities to use, the channel design, and coordinating alternative supply sources. Our analytic inventory-control model and a simulation model showed that procurement-cost savings largely outweigh reverse logistics costs and that information management is essential. These findings provide a basis for significantly expanding the usage of the novel parts supply source, thereby cutting procurement costs.
The Ombudsman: Reaping Benefits from Management Research: Lessons from the Forecasting Principles Project
Authors: Armstrong J. Scott , Pagell Ruth
Published: January 2004

It is often claimed that managers do not read serious research papers in journals. If true, this neglect would seem to pose a problem because journals are the dominant source of knowledge in management science. By examining results from the forecasting principles project, which was designed to summarize all useful knowledge in forecasting, we found that journals have provided 89 percent of the useful knowledge. However, journal papers relevant to practice are difficult to find because fewer than three percent of papers on forecasting contain useful findings. That turns out to be about one useful paper per month over the last half century. Once found, papers are difficult to interpret. Managers need low-cost, easily accessible sources that summarize advice (principles) from research; journals do not meet this need. To increase the rate of progress in developing and communicating principles, researchers, journal editors, textbook writers, software developers, Web-site designers, and practitioners should make some changes. We offer some examples: Researchers should directly study forecasting principles. Journal editors should actively solicit papers; invited submissions were about 20 times better than standard submissions at producing useful findings that were often cited, and they do so at lower cost. Textbook writers should focus on principles so that readers can apply knowledge. Web-site and software developers should provide practitioners with low-cost ways to use principles. Practitioners should apply the principles that are currently available.
Clinical Guidelines in Dentistry: Their Benefits, Limitations and Dentolegal Implications
Authors: Palmer Nikolaus AO
Published: January 2004

This paper examines and reviews the benefits, limitations and legal implications of guidelines formulated specifically for general dental practitioners. As more guidelines are developed and become more influential in the way dentists practise and become more accountable, it is of paramount importance that that they are scientifically valid, relevant to the practitioners who use them, and are rigorously evaluated before adoption.
Thermal Behavior of Natural and Cation-Exchanged Clinoptilolite from Sardinia (Italy)
Authors: Langella Alessio , Pansini Michele , Cerri Guido , Cappelletti Piergiulio , de’Gennaro Maurizio
Published: January 2004

The thermal behavior of two clinoptilolites from an epiclastic and a pyroclastic deposit of central-northern Sardinia and of their exchanged forms (Li, Na, K, Cs, Mg, Ca, Sr and ammonium) were investigated by differential thermal analysis and thermogravimetry up to 1000°C. Their thermal stability was studied by evaluating the residual crystallinity (expressed as rehydration capacity) after 2 h thermal treatments at 450, 600 and 900°C. The water loss at 1000°C was linearly related to the radius (r) and the charge (z) of the exchangeable cations by the equations r2/z or r3/z, which are proportional to the inverse of the charge density over the surface or to the charge density over the volume of the cations.

The cation composition plays a crucial role in determining the thermal behavior of clinoptilolite. The presence of cations such as Cs or K, which have low surface or volume charge densities, was found to increase the thermal resistance. In particular, the crystallinity of Cs- and K-exchanged forms of both clinoptilolites was not affected by thermal treatment at 450°C and was only slightly reduced by thermal treatment at 600°C.

Predicting the thermal behavior of natural and cation-exchanged forms of these clinoptilolites can provide useful information for possible applications in catalysis, in the case of high thermal stability, or for thermal transformation into ceramics or lightweight aggregates.
Properties and Utilization of Zeolite-Blended Portland Cements
Authors: Janotka Ivan , Krajči L’udovít , Dzivák Martin
Published: January 2004

The resistance to acidic and sulfate attack of Portland-pozzolan cement containing 35 wt.% of zeolite was compared with that of unamended Portland cement. Mortar specimens kept in 0.5% and 1.0% HCl solution, 5% Na2SO4 solution, and in reference water for 365 and 720 days were tested using a set of physical-mechanical and chemical techniques. The ability of mortars containing zeolitic cements with 15 to 50 wt.% of zeolite to protect steel against corrosion was verified by a potentiodynamic method. Mortar with zeolitic cement performs better when exposed to 1% HCl solution due to the presence of a finer pore matrix, a hydrate phase poorer in CaO-containing hydration products with lower leachability, and the high resistance of zeolite material itself to acidic attack, compared with Portland cement and siliceous sand. The improved sulfate resistance of the mortar with zeolitic cement is caused by the decreased C3A in the cement blend in comparison with that in Portland cement, a reduction in SO3 binding into the cement paste and decreased amount of CaO-containing hydration products capable of reacting with a sulfate solution forming voluminous reaction products, and consequent crack propagation, large expansion and structural disintegration. Passivation of steel in mortars with blends of Portland cement to zeolite percentage ratios of 85/15, 75/25 and 65/35 by weight is comparable to that of Portland cement mortar. This is particularly important because the mortar with zeolitic cement exhibits late strengths similar to that of Portland cement mortar. This confirms that zeolitic cement can replace Portland cement in many applications with the advantage of higher resistance to acidic and sulfate attack.
Determination of Layer-Charge Characteristics of Smectites
Authors: Christidis G. E. , Eberl D. D.
Published: January 2004

A new method for calculation of layer charge and charge distribution of smectites is proposed. The method is based on comparisons between X-ray diffraction (XRD) patterns of K-saturated, ethylene glycol-solvated, oriented samples and calculated XRD patterns for three-component, mixed-layer systems. For the calculated patterns it is assumed that the measured patterns can be modeled as random interstratifications of fully expanding 17.1 Å layers, partially expanding 13.5 Å layers and non-expanding 9.98 Å layers. The technique was tested using 29 well characterized smectites. According to their XRD patterns, smectites were classified as group 1 (low-charge smectites) and group 2 (high-charge smectites). The boundary between the two groups is at a layer charge of −0.46 equivalents per half unit-cell. Low-charge smectites are dominated by 17.1 Å layers, whereas high-charge smectites contain only 20% fully expandable layers on average. Smectite properties and industrial applications may be dictated by the proportion of 17.1 Å layers present. Non-expanding layers may control the behavior of smectites during weathering, facilitating the formation of illite layers after subsequent cycles of wetting and drying. The precision of the method is better than 3.5% at a layer charge of −0.50; therefore the method should be useful for basic research and for industrial purposes.
Crystallization Conditions of Fundamental Particles from Mixed-Layer Illite-Smectite of Bentonites Based on Isotopic Data (K-Ar, Rb-Sr and δ18O)
Authors: Clauer Norbert , Liewig Nicole , Pierret Marie-Claire , Toulkeridis Theofilos
Published: January 2004

Rb-Sr and oxygen isotope studies, in addition to K-Ar isotopic determinations published previously, are reported on diagenetic and hydrothermal fundamental particles (particle thickness of 0.03 to 0.05 nm and particle ab size of 0.02–0.05 µm) of the East-Slovak Basin. The combined data set allows us to ascertain the crystallization conditions of the illite material from two bentonite units collected at two basinal sites located ~20 km apart, and characterized by prolonged diagenetic conditions induced by progressive burial. A bentonite rock characterized by a short hydrothermal event from the Zempleni mountains to the SW of the East-Slovak basin is also studied.

For the two first sites, the δ18O values increase in one case and decrease in the other, when the size of the diagenetic fundamental particles from bentonite samples increases. These variations suggest that temperature increased in one and decreased in the second of the two samples collected in the basin, while the particles were growing. In the case of the hydrothermal bentonite, the δ18O values of the different size-fractions consisting of fundamental particles remain about constant, suggesting constant temperature and fluid chemistry.

The Rb-Sr dates of the fundamental particles of the three bentonite rocks were systematically higher than the corresponding K-Ar ages. The 87Sr/86Sr ratios, which are initially involved in the particle nucleation, appeared higher than that of contemporaneous sea-water. In all cases, the initial 87Sr/ 86Sr ratio decreases when particle size increases, which implies supply of external Sr into the bentonite units. This external Sr seems to have had an 87Sr/86Sr ratio close or identical to that of the contemporaneous sea water. This means that Sr, probably of sea-water origin, progressively diffused from host shales into the bentonite units, during burial diagenesis. In turn it favors the suggestion made previously about diffusion of K from shales into the bentonite layers during illitization of the smectite from these units.
Raman and X-ray Diffraction Data on Anatase in Fired Kaolins
Authors: Murad Enver
Published: January 2004

The Raman spectra of many kaolins are dominated by bands from ancillary anatase. Fired samples of a commercial anatase-bearing kaolin from the Jari River deposit in Brazil showed significant variations of Raman spectra as a function of the firing temperature. The spectra showed the full range of anatase bands up to a firing temperature of 900°C. From 950°C the background increased significantly, leading to an unfavorable signal/noise ratio that allowed observation of only the most intense (Eg) band at ~144 cm−1. X-ray diffraction (XRD), however, confirmed that this band, which persists up to 1200°C, results from anatase. Two factors may be responsible for the high thermal stability of anatase in this sample: its relatively large particle size of ~120 nm and possible reactions with Si and Al that become liberated during kaolinite breakdown. When evaluated with circumspection, Raman and XRD data on anatase can serve as ‘thermometers’ to elucidate the thermal history of fired anatase-bearing kaolins and other anatase-bearing clays.
Low-Temperature Synthesis of Micas under Conventional- and Microwave-Hydrothermal Conditions
Authors: Komarneni Sridhar , Newalkar Bharat L.
Published: January 2004

Several micas containing different octahedral and interlayer cations were synthesized at different temperatures under conventional- and microwave-hydrothermal conditions and these phases were characterized by powder X-ray diffraction, solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. A Zn K-mica with Zn in the octahedral sheets and K in the interlayers was synthesized in the temperature range 150–200°C and a novel Zn Rb-mica with Zn in the octahedral sheets and Rb in the interlayers was synthesized at 200°C. The synthesis of either Mg, Co or Ni K-micas, however, was found to be difficult or impossible at these low temperatures. Solid-state 29Si MAS-NMR revealed that the Al in the tetrahedral sites is disordered with several nearest-neighbor Si environments. In general, microwave-assisted hydrothermal conditions led to better crystallization of the Zn K-micas compared with the conventional method.
Biologie im Supermarkt: Zwischen Fett‐Ecke und Light‐Quark
Authors: Probst Wilfried , Scharf Karl‐Heinz
Published: January 2004

Wie Befragungen an Jugendlichen zeigten, sind „Einkaufslandschaften”︁ wie Supermärkte und Warenhäuser mittlerweile zu Orten der Freizeitgestaltung geworden. Im Hinblick auf die einseitige Beeinflussung der Kinder und Jugendlichen durch Angebote und Werbung sollte eine Konsumentenbildung vor Ort angestrebt werden. Erprobungen mit Lehramtsstudierenden, Schulklassen und Lehrkräften haben gezeigt, dass „Biologie im Supermarkt”︁ eine sinnvolle Ergänzung des Unterrichts darstellen kann. Dabei können in diesem Unterricht auch viele allgemeinbiologische und im Lehrplan aufgeführte Inhalte bearbeitet werden. Dies wird am Beispiel des Themas „Fette und fette Öle”︁ näher ausgeführt.
Gut gerüstet mit eisernem Schuhwerk
Authors: Knoll Ulrike
Published: January 2004

In der unwirtlichen Umgebung der Unterwassergeysire im Indischen Ozean kriecht eine Schnecke auf eiserner Sohle. Ihren Fuß ziert ein schuppenbesetzter Stiefel, der aus ungewöhnlichen Werkstoffen besteht.
Heinz Tiedemann
Authors: Niehrs Christof
Published: January 2004

Heinz Tiedemann ist der letzte noch lebende Repräsentant der deutschen Schule, die einst als „Entwicklungsmechanik”︁ bezeichnet wurde. Er widmete sein wissenschaftliches Leben der Untersuchung der Amphibienentwicklung und hat Pionierarbeit geleistet, um embryonale Induktoren zu charakterisieren. Seine Entdeckungen sind heute besonders aktuell, denn mit solchen Wachstumsfaktoren versucht man das Verhalten von Stammzellen zu beeinflussen, um Therapien für degenerative Krankheiten zu entwickeln. Seine „Erinnerungen an das XX. Jahrhundert”︁ enthalten spannende Einblicke in die Wissenschaftsgeschichte und die Anfänge der molekularen Entwicklungsbiologie.
Pramlintide reduces postprandial glucose excursions when added to insulin lispro in subjects with type 2 diabetes: a dose‐timing study
Authors: Maggs David G. , Fineman Mark , Kornstein Jonathan , Burrell Terrie , Schwartz Sherwyn , Wang Yan , Ruggles James A. , Kolterman Orville G. , Weyer Christian
Published: January 2004

Background

To assess the postprandial glucose‐lowering effect of the human amylin analog pramlintide when given with insulin lispro in subjects with type 2 diabetes, with an emphasis on the optimal dose timing relative to meals.

Methods

In this randomized, single‐blind, placebo‐controlled, five‐way crossover study, 19 subjects with type 2 diabetes using insulin lispro underwent five consecutive mixed‐meal tests. In randomized order, subjects received subcutaneous injections of placebo at −15 min or 120‐µg pramlintide at −15, 0, +15, or +30 min relative to the standardized breakfast after an overnight fast. Insulin lispro was injected at 0 min at doses that were adjusted appropriately for both the content of the standardized meal and the anticipated effects of pramlintide. Plasma glucose concentrations were measured before and during the 4‐h postmeal period.

Results

When injected at 0 min, pramlintide reduced the postprandial glucose excursion by 81% compared to insulin lispro + placebo (incremental AUC0–4 h (mean ± SE) 2.0 ± 1.5 vs. 10.4 ± 2.2 mmol/h/L, P < 0.05). When pramlintide was injected at −15, +15, and +30 min, the postprandial incremental glucose AUC0–4 h was also significantly reduced (P < 0.05), but to a lesser extent (42 to 73%). Pramlintide treatment was well tolerated and no serious adverse events were reported.

Conclusions

Administration of pramlintide either at or just prior to a meal caused a greater reduction in postprandial glucose than either administration of placebo or postmeal pramlintide injections in subjects with type 2 diabetes treated with a rapid‐acting insulin analog, insulin lispro. Copyright © 2004 John Wiley & Sons, Ltd.
Glutathione metabolism and oxidative stress in neonatal rat tissues from streptozotocin‐induced diabetic mothers
Authors: Raza Haider , John Annie
Published: January 2004

Background

Diabetes in pregnancy has been reported to cause congenital malformations in the offspring. Hyperglycemia‐induced teratogenecity is related to the increased oxidative stress and depletion of glutathione (GSH) in fetal tissues.

Methods

In the present study, we have examined the levels of reactive oxygen species (ROS) and peroxide production in the tissues of neonatal rats and in the pancreas of diabetic mother rats. Diabetes was induced one day after pregnancy by a single injection of streptozotocin (60 mg/kg body weight). Different tissues from one‐day‐old neonates and the pancreas from the mothers were collected to study the level of oxidative stress and GSH metabolism.

Results

An increase in ROS and peroxide production was observed in the pancreas of diabetic rats and in the liver, kidney, brain and skin of the neonates of the diabetic mothers. The catalytic activity of cytochrome P450 2E1 (CYP2E1) was also increased in these tissues from diabetic rats. With the exception of the kidney, the GSH concentration was significantly lower in the tissues of neonates and in the pancreas of diabetic mothers.

Conclusion

This reduction in GSH concentration was presumably associated with its increased utilization, due to increased production of peroxides and also due to its reduced regeneration. The study may have an implication in understanding the pathology of diabetic complications in pregnancy and sensitivity toward antioxidant therapy during pregnancy. Copyright © 2004 John Wiley & Sons, Ltd.
Progenitor cells in the adult pancreas
Authors: Holland Andrew M. , Góñez L. Jorge , Harrison Leonard C.
Published: January 2004

The β‐cell mass in the adult pancreas possesses the ability to undergo limited regeneration following injury. Identifying the progenitor cells involved in this process and understanding the mechanisms leading to their maturation will open new avenues for the treatment of type 1 diabetes. However, despite steady advances in determining the molecular basis of early pancreatic development, the identification of pancreatic stem cells or β‐cell progenitors and the molecular mechanisms underlying β‐cell regeneration remain unclear. Recent advances in the directed differentiation of embryonic and adult stem cells has heightened interest in the possible application of stem cell therapy in the treatment of type 1 diabetes. Drawing on the expanding knowledge of pancreas development, β‐cell regeneration and stem cell research, this review focuses on progenitor cells in the adult pancreas as a potential source of β‐cells. Copyright © 2004 John Wiley & Sons, Ltd.
The role of lipids and protein kinase Cs in the pathogenesis of diabetic retinopathy
Authors: Curtis T. M. , Scholfield C. N.
Published: January 2004

Diabetic retinopathy is one of the most common complications of diabetes and is a major cause of new blindness in the working‐age population of developed countries. While the exact pathogenic basis of this condition remains ill defined, it is clear that hyperglycaemia is a critical factor in its aetiology. Protein kinase C (PKC) activation is one of the sequelae of hyperglycaemia and it is thought to play an important role in the development of diabetic complications. This review questions the currently held dogma that PKC stimulation in diabetes is solely mediated through the overproduction of palmitate and oleate enriched diacylglycerols. Blood glucose concentrations are closely tracked by changes in the levels of free fatty acids and these, in addition to oxidative stress, may account for the aberrant activation of PKCs in diabetes. Little is known about why PKCs fail to downregulate in diabetes and efforts should be directed towards acquiring such information. Considerable evidence implicates the PKCβ isoform in the pathogenesis of diabetic retinopathy, but other isoforms may also be of relevance. In addition to PKCs, it is evident that novel diacyglycerol‐activated non‐kinase receptors could also play a role in the development of diabetic complications. Therapeutic agents have been developed to inhibit specific PKC isoforms and PKCβ antagonists are currently undergoing clinical trials to test their toxicity and efficacy in suppressing diabetic complications. The likely impact of these drugs in the treatment of diabetic patients is considered. Copyright © 2004 John Wiley & Sons, Ltd.
The effects of price and policy on marijuana use: what can be learned from the Australian experience?
Authors: Williams J.
Published: January 2004

This research examines the responsiveness of the demand for marijuana to changes in its money price and criminal status using data on individuals from the Australian National Drug Strategy's Household Surveys (NDSHS). The results suggest that both the prevalence of marijuana use and the conditional demand for marijuana in the general population are responsive to changes in its money price. Significant differences are found in the effect of price on participation in marijuana use across age‐groups, with participation by youth more price sensitive than participation by older age‐groups. Similarly, the effect of the legal status of marijuana use on the participation decision is found to differ across age‐groups and gender. Specifically, decriminalisation is associated with an increases in the prevalence of use by males over the age of 25. There is no evidence that decriminalisation significantly increases participation in marijuana use by either young males or females, or that decriminalisation increases the frequency of use among marijuana users. Copyright © 2003 John Wiley & Sons, Ltd.
Excess capacity and expense preference behaviour in National Health Systems: an application to the Spanish public hospitals
Authors: Rodríguez‐Álvarez Ana , Knox Lovell C. A.
Published: January 2004

The aim of this paper is to study excess capacity in National Health System (NHS) hospitals, which have the characteristics of a bureaucracy, within a theoretically consistent framework. In this sense, we develop and estimate an empirical model which has not previously been applied to this problem. This model, based on an input distance function, is attractive for at least two reasons. Unlike the production function, the input distance function is valid for multiproduct technologies such as that of hospitals, and in contrast to the cost function it permits testing of the cost minimisation hypothesis and therefore allows expense preference behaviour in the context of NHS hospitals. We present an application to the Spanish public hospital sector and observe persistent allocative inefficiency in variable inputs and overcapitalisation in these hospitals. Hence, our results suggest that this sector is not in long‐run equilibrium and that adjustments in variable inputs and capital equipment investments are necessary to control hospital cost. Copyright © 2003 John Wiley & Sons, Ltd.
Lack of multiplicative transitivity in person trade‐off responses
Authors: Schwarzinger Michaël , Lanoë Jean‐Louis , Nord Erik , Durand‐Zaleski Isabelle
Published: January 2004

Background: The person trade‐off (PTO) is a technique for eliciting preferences for resource allocation across patient groups. In principle PTO responses should satisfy a requirement of multiplicative transitivity, i.e. that if people consider treatment of 1 in state A to be equivalent to treating 10 in state B, and 1 in state B to be equivalent to 10 in state C, then they should find 1 in state A equivalent to 100 in state C. Earlier studies addressing labelled diseases (specific diagnoses), have shown multiplicative intransitivity of the PTO responses. Our purpose was to test multiplicative transitivity in the case of health states described with the EuroQol instrument only and to find a possible framing effect such as the number of persons in the reference intervention.

Methods: Forty‐four master degree students were asked to fill in a questionnaire addressing four chronic health states. Their task consisted in (1) ranking the states by severity, (2) valuing each of them by the means of the time trade‐off, and (3) doing the PTO for all the 10 possible pairwise combinations of the four chronic states plus a fatal one. In a subsequent questionnaire the number of persons in the reference intervention in the PTO was increased from 10 to 100. Multiplicative transitivity was studied in subjects who demonstrated a willingness to trade off and consistency in ranking individual values.

Results: None of the 39 subjects included satisfied a minimum multiplicative transitivity requirement in PTO responses. Internal consistency was not improved when the PTO involved health states close to each other in terms of severity, nor when the prevention of death was not the reference intervention. For the 22 subjects having answered both types of questionnaire, increasing the number of persons in the reference intervention did not improve multiplicative transitivity.

Conclusions: The PTO holds promise as a useful method for determining social preferences for priority setting, inasmuch as it captures distributive concerns that individual utility techniques such as the time trade‐off do not address. But the lack of multiplicative transitivity in PTO responses is unsatisfactory, and ways to reduce this problem need to be explored. Copyright © 2003 John Wiley & Sons, Ltd.
Evidence of range bias in contingent valuation payment scales
Authors: Whynes David K. , Wolstenholme Jane L. , Frew Emma
Published: January 2004

The payment scale format has been widely used in willingness‐to‐pay studies in health care. Concerns have been expressed that the format is, in theory, prone to range bias, although this proposition has not been tested directly. We report the findings of a contingent valuation questionnaire study of colorectal cancer screening, wherein different subjects were provided with payment scales of two different lengths. Whilst the long‐scale instrument included scale values up to £1000, the short‐scale version extended only to £100. After controlling for inter‐sample differences in, for example, income, education and health behaviour, it emerged that the long‐scale instrument produced a mean willingness to pay more than 30% higher than that resulting from the short‐scale version. We believe our findings to be strongly supportive of the likelihood of range bias in payment‐scale instruments, with important consequences for the estimation of both average valuation and consumer surplus. Copyright © 2003 John Wiley & Sons, Ltd.
Managed care and shadow price
Authors: Ma Ching‐to A.
Published: January 2004

A managed‐care company must decide on allocating resources of many services to many groups of enrollees. The profit‐maximizing allocation rule is characterized. For each group, the marginal utilities across all services are equalized. The equilibrium has an enrollee group shadow price interpretation. The equilibrium spending allocation can be implemented by letting utilitarian physicians decide on service spending on an enrollee group subject to a budget for the group. Copyright © 2003 John Wiley & Sons, Ltd.
Bayesian estimation of cost‐effectiveness: an importance‐sampling approach
Authors: Heitjan Daniel F. , Li Huiling
Published: January 2004

We describe a method for estimating the cost‐effectiveness of a new treatment compared to a standard, using data from a comparative clinical trial. We quantify the clinical effectiveness as a binary variable indicating success or failure. The underlying statistical model assumes that costs are uncensored and follow separate gamma distributions in each of the groups defined by the four possible combinations of treatment arm and effectiveness outcome. The method is subjectivist, in that it represents prior uncertainty about model parameters with a probability distribution, which we update via Bayes's theorem to produce a posterior distribution. We approximate the posterior by importance sampling, a straightforward simulation method. We illustrate the method with an analysis of cost (derived from resource usage data) and effectiveness (measured by one‐year survival) in a clinical trial in heart disease. The example demonstrates that the method is practical and provides for a flexible data analysis. Copyright © 2003 John Wiley & Sons, Ltd.
Migration of polyethylene debris along well‐fixed cemented implants
Authors: Massin P. , Viguier E. , Flautre B. , Hardouin P. , Astoin E. , Duponchel B.
Published: January 2004

Implants, consisting of smooth Inox cylinders, were cemented into the lower femur and upper tibia of nine sheep to study the distal migration of polyethylene particles. Some implants had a titanium‐bead porous coat at the proximal end. These were of three types: In the first type, the porous coat was covered with hydroxyapatite to obtain a bony seal; the second type was prepared for a polymethylmethacrylate seal; in the third type, the porous zone was surrounded by a 2‐mm‐thick space to allow the formation of a fibrous seal. Small polyethylene particles were injected into the knees once a week during the third and fourth months after implantation. The animals were euthanized 2 months later. Major longitudinal sections of the implants and the surrounding bone were examined under a polarized light microscope. Birefringent particles were counted at the cement‐bone and cement‐implant interfaces. Osteolysis was not observed. None of the seals significantly decreased the migration of particles around the cemented part of the implants. Particles were observed in cement fissures and vacuoles. They migrated at both interfaces and in the bone itself. They were visible in marrow spaces between bone trabeculae. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 140–148, 2004
Biological properties of acid etched titanium implants: Effect of sandblasting on bone anchorage
Authors: Szmukler‐Moncler S. , Perrin D. , Ahossi V. , Magnin G. , Bernard J. P.
Published: January 2004

The SLA (sandblasted with large grit and acid etched) surface is a textured surface that has been documented to lead to a rapid and strong implant fixation. The purpose of the present study was to determine the contribution of sandblasting in addition to etching to implant anchorage. It was also aimed to determine if the pits carved during etching alone have a bone‐interlocking capacity that leads to microanchorage between the implant and bone. SLA implants and machined‐and‐acid‐etched (MA) implants were placed in the maxilla of Land Race pigs. After 10 weeks of healing, they were reverse torqued. The reverse torque of the SLA and MA implants was 157.29 ± 38.04 N cm and 105.33 ± 25.12 N cm, respectively. Sandblasting increased bone anchorage by 49.3%; the difference was statistically significant (p = .028). Bone was found attached to both surfaces; bone ingrowth was found in the pits of both surfaces. It is suggested that the two surfaces are able to generate bone interlocking and mechanical coupling at the interface. When finite‐element modeling is performed with these surfaces, it is suggested that the bound mode be used instead of the slip mode. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 149–159, 2004
Formation of defined microporous 3D structures starting from cross‐linked hydrogels
Authors: Barbucci Rolando , Leone Gemma
Published: January 2004

A new and simple technique was developed to obtain polysaccharide (hyaluronane, alginate and carboxymethylcellulose) ‐based hydrogels with a defined porous morphology. The technique consists of stratifying a cross‐linked hydrogel on a filter with known pore diameter. CO2 bubbles, produced by the addition of HCl to a porogen salt NaHCO3, are forced to pass through the filter, and they induce the hydrogel to assume a porous morphology. The presence and distribution of pores was confirmed by scanning‐electron microscopy (SEM). A strict correspondence was found between the porosity of the filter and the pore diameter in the hydrogels. Water uptake measurements showed a decreased amount of water taken up by the porous hydrogels compared with the native hydrogels, due to a compacting of the material. An explanation of the porous material properties of Hyal hydrogel was given on the basis of FTIR spectra. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 117–126, 2004
In vivo aging test for a bioactive bone cement consisting of glass bead filler and PMMA matrix
Authors: Shinzato Shuichi , Nakamura Takashi , Kawanabe Keiichi , Kokubo Tadashi
Published: January 2004

The degradation of a new bioactive bone cement (GBC), comprised of an inorganic filler (bioactive MgO‐CaO‐SiO2‐P2O5‐CaF2 glass beads) and an organic matrix [high‐molecular‐weight polymethyl methacrylate (PMMA)], was evaluated in an in vivo aging test. Hardened rectangular specimens (20 × 4 × 3 mm) were prepared from two GBC formulations (containing 50% w/w [GBC50] or 60% w/w [GBC60] bioactive beads) and a conventional PMMA bone cement control (CMW‐1). Initial bending strengths were measured with the use of the three‐point bending method. Specimens of all three cements were then implanted into the dorsal subcutaneous tissue of rats, removed after 3, 6, or 12 months, and tested for bending strength. The bending strengths (MPa) of GBC50 at baseline (0 months), 3, 6, and 12 months were 136 ± 1, 119 ± 3, 106 ± 5 and 104 ± 5, respectively. Corresponding values were 138 ± 3, 120 ± 3, 110 ± 2 and 109 ± 5 for GBC60, and 106 ± 5, 97 ± 5, 92 ± 4 and 88 ± 4 for CMW‐1. Although the bending strengths of all three cements decreased significantly from 0 to 6 months, those of GBC50 and GBC60 did not change significantly thereafter, whereas that of CMW‐1 declined significantly between 6 and 12 months. Thus, degradation of GBC50 and GBC60 does not appear to continue after 6 months, whereas CMW‐1 degrades progressively over 12 months. Moreover, the bending strengths of GBC50 and GBC60 (especially GBC60) were significantly higher than that of CMW‐1 throughout. It is believed that GBC60 is strong enough for use under weight‐bearing conditions and that its mechanical strength is retained in vivo; however, its dynamic fatigue behavior will need assessment before application in the clinical setting. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 132–139, 2004
Bone‐defect healing with calcium‐sulfate particles and cement: An experimental study in rabbit
Authors: Orsini Giovanna , Ricci John , Scarano Antonio , Pecora Gabriele , Petrone Giovanna , Iezzi Giovanna , Piattelli Adriano
Published: January 2004

Calcium sulfate (CaS) has been shown to be a reasonable alternative to autogenous bone graft for treating bone lesions in dentistry. The aim of this work was an histological study of the bone healing of defects treated with calcium sulfate in the form of cement or beads, in animal. Eight New Zealand rabbits, weighing about 2.5 Kg were used in this study. In each rabbit, four 6 mm bone defects were created in the tibial metaphysis. The 2 defects in the right tibia were filled with calcium sulfate as cement, while the 2 defects in the left one were filled with calcium sulfate as beads. Four rabbits were killed after respectively 2 and 4 weeks, with an intravenous injection of Tanax, and the block sections, containing the bone defects, were retrieved. A total of 16 defects filled by cement and a total of 16 defects filled by beads were retrieved. The specimens were processed to obtain thin ground sections with the Precise 1 Automated System. In the first phases of healing it was possible to observe an intense osteoblastic activity, and in some areas osteoid matrix was present. After two weeks the calcium sulfate (both cement and beads) was still present, and biological fluids and cells were present inside the material. Newly formed bone surrounded the calcium sulfate and filled about 10% of the defect. After four weeks the calcium sulfate was almost completely resorbed and substituted by new bone. Approximately 34% of the defects were filled by newly formed bone. BEI and XRM evaluations showed the structural components of the filled defects. In none of the specimens were inflammatory cells present. No significant differences were found using both calcium sulfate as cement and beads, and they both have shown a high biocompatibility, appearing to promote newly bone formation in the rabbit model, and they did not induce any untoward effect on the bone regeneration processes. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 199–208, 2004
Properties and biocompatibility of polypropylene graft copolymer films
Authors: El‐Rehim H. A. Abd , El‐Arnaouty M. B.
Published: January 2004

Modifying the surfaces of polymers has received a great deal of attention, because it could bring about specific surface characteristics such as antithrombogenic property. Therefore, N‐vinyl pyrrolidone/sodium acrylate (NVP/Na‐AAc) binary monomers were introduced onto polypropylene (PP) films by a radiation grafting method. The effect of solvent and comonomer composition on the degree of grafting was determined. Studies of the mechanical properties and water content of such graft copolymers showed that as the grafting yield increases the elongation percent decreases. However, the water content increases with increasing grafting yield. The blood compatibility of the original PP and PP‐g–NVP/Na‐AAc films was evaluated by determination of the extent of platelet adsorption and thrombus formation. The blood compatibility of PP‐g–NVP/Na‐AAc seems to be better than that of original PP. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 209–215, 2004
Electric‐current‐induced detachment of Staphylococcus epidermidis strains from surgical stainless steel
Authors: van der Borden A. J. , van der Mei H. C. , Busscher H. J.
Published: January 2004

Infection of percutaneous biomaterials implants, such as fixation frames used for the repair of complicated fractures in orthopedics, is a major complication that almost inevitably leads to replacement of the implant. As antibiotic therapy usually has little impact on biomaterial‐associated infections, it is the aim of this article to examine whether implant‐associated Staphylococcus epidermidis and Staphylococcus aureus strains could be stimulated to detach from a surgical stainless steel anode during application of an electric current. First, bacteria were allowed to adhere from a flowing suspension of physiological ionic strength in a parallel plate flow chamber to a stainless‐steel surface, after which the suspension was replaced by a bacterium‐free solution with a specified ionic strength (0.5–150‐mM potassium phosphate). DC currents ranging from 15 to 125 μA were applied to induce bacterial detachment. Initial detachment decreased with increasing ionic strength at 100 μA. The percentage detachment achieved by application of an electric current after 2.5 h was highest (95%) in 1‐mM potassium phosphate and decreased to 15% when the ionic strength exceeded 40 mM. The electric current did not significantly affect the percentage detachment, but initial detachment rates increased with increasing current from 1000 cm−2 s−1 at 15 μA to 7000 cm−2 s−1 at 125 μA. Although different isolates of S. epidermidis and S. aureus showed different patterns of current‐induced detachment, all strains could be stimulated to detach. The results of this study define ionic‐strength conditions and electric currents yielding staphylococcal detachment from surgical stainless steel and therewith point to a pathway for the treatment and prevention of percutaneous metal‐implant infection. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 160–164, 2004
The effect of tranexamic acid in fibrin sealant on adhesion formation in the rat
Authors: Wiseman David , Lyachovetsky Yacov , Keidan Ilan , Trout J. Richard , Nur Israel
Published: January 2004

The objective of the research was to determine the effect of the type, dose, and volume of anti‐fibrinolytic agents (tranexamic acid, aprotinin) added to fibrin formulations, on adhesion development. Adhesions were induced in 228 male rats by creating apposing parietal and visceral peritoneal defects. Animals were randomized to receive no treatment or a fibrin formulation containing aprotinin or tranexamic acid. Seven days later the incidence of adhesions, and the force and energy required to detach them, were determined. Adhesions developed in 13/13 rats in the control and aprotinin groups. Treatment with fibrin (100 mg/ml tranexamic acid) resulted in adhesions in 4/14 rats (as strips, p ≤ 0.0005), 4/10 rats (as spray, p ≤ 0.0036), and 12/15 rats (by drip). The reduction of adhesions was dependent on the concentration of tranexamic acid with strip and spray application. Using commercial formulations, tranexamic‐acid–containing fibrin (10/15, p = 0.042), but not aprotinin‐containing fibrin (13/15), reduced the incidence of side‐wall adhesions from 15/15 in controls. Fibrin containing either tranexamic or aprotinin reduced the incidence and severity of adhesions. This effect was greater when tranexamic acid was used and was dependent on the mode of administration, the volume, and to a degree, the concentration of tranexamic acid. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 222–230, 2004
The development of theoretical relationships between some handling parameters (setting time and setting temperature), composition (relative amounts of initiator and activator) and ambient temperature for acrylic bone cement
Authors: Milner Richard
Published: January 2004

Commercially available acrylic bone cements are two‐component systems based on the polymerization of methyl methacrylate around poly(methyl methacrylate) particles. When benzoyl peroxide (BPO), which is the initiator, in the powder component meets accelerator (N,N‐dimethyl‐p‐toluidine (DMpT)) in the liquid component, radicals are produced, initiating the polymerization. This solidifies the cement. In this work, kinetic expressions have been developed that describe the relationship between bone cement setting time on the one hand, and BPO and DMpT concentrations on the other. Changes in setting time with ambient temperature follow a complex relationship, because both the polymerization process (initiation, propagation, and termination) and the swelling and dissolution of the polymer particles contribute to setting. The contribution of polymer swelling and dissolution to the setting process was determined by developing a relationship between the doughing time, which is substantially independent of DMpT or BPO concentrations, and ambient temperature. A value of 64 kJ mol−1 was found for the activation energy for this process. An activation energy for the overall setting process of 68 kJ mol−1 was determined from setting‐time measurements over several ambient temperatures. This indicates that the sensitivity of setting time to temperature depends more on swelling and dissolution than on the polymerization process. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 68B: 180–185, 2004