Eicosapentaenoic acid suppression of systemic inflammatory responses and inverse up-regulation of 15-deoxyΔ(12,14) prostaglandin J2 production.

Background And Purpose: Eicosapentaenoic acid (EPA) has been shown to suppress immune cell responses, such as cytokine production and downstream PG production in vitro. Studies in vivo, however, have used EPA as a minor constituent of fish oil with variable results. We investigated the effects of EPA on systemic inflammatory responses as pure EPA has not been evaluated on immune/inflammatory responses in vivo.

Effects of glass ionomer cements on bone tissue.

In vivo biocompatibility of glass ionomer cements (GICs) was evaluated for use in orthopaedic surgery using a rat model and compared with conventional bone cement, Polymethyl methacrylate, PMMA. The unset GICs and PMMA were inserted into the marrow cavities of rat femora and retained in situ for various periods of time. The PMMA bone cement showed complete biocompatibility with no interference with reparative bone.

Time dependence of the mechanical properties of GICs in simulated physiological conditions.

The mechanical properties of glass-ionomer cements (GICs) have been satisfactory for dental applications and have shown their potential in orthopedic surgery. Because the physiological environment in orthopedics is different from dentistry by unavoidable contamination with blood and other fluids such as normal saline used during an operation, the determination of GICs for orthopedic applications should be performed in an appropriate environment. The properties of a novel resin-modified GIC, S430, for orthopedic applications were evaluated in simulated orthopedic conditions by an early exposure to and long-term storage in normal saline.

Comparison of the material properties of PMMA and glass-ionomer based cements for use in orthopaedic surgery.

The intrinsic benefits of low exotherm and bioactivity have generated interest in utilizing glass-ionomer cements (GIC) as a bone cement replacement in orthopaedic surgery. This paper is concerned with evaluating the mechanical properties of compressive strength, flexural strength, and fracture toughness for two traditional GICs, one resin-modified GIC (an experimental bone cement) and two polymethylmethacrylate (PMMA) cement systems. To determine the suitability of a GIC system for use in the clinical orthopaedic setting, the additional characteristics of setting exotherm and setting time have also been evaluated.

Interfacial fracture toughness between bovine cortical bone and cements.

To evaluate the bonding strength of the interfaces within the cemented arthroplasty system, various mechanical tests have been used. Conventional push-out and pull-out tests cannot reveal the actual bonding property of the interface because of the significant influence of surface roughness on the measured adhesion and the failure to account for the mismatch of elastic modulus across the interface. An alternative fracture mechanics approach, which considers the mix of opening and shear modes of the crack tip loading associated with the testing system and the elastic mismatch of materials across the interface, was used to evaluate the bonding ability of various cements.

Comparison of failure characteristics of a range of cancellous bone-bone cement composites.

Over the past decade, orthopedic surgery has embraced an increase in the depth of cement penetration into the adjacent cancellous bone structure. The resultant interdigitation transforms this zone into a thick layer of continuous interpenetrating composite material. The failure behavior of the composite formed with a number of potential bone cements with different bonding ability was investigated.

Mid-femur geometry and biomechanical properties in 15- to 18-yr-old female athletes.

Purpose: Right-leg mid-femur geometry and biomechanical indices of bone strength were compared among elite cyclists (CYC), runners (RUN), swimmers (SWIM), triathletes (TRI), and controls (C)-10 subjects per group.

Methods: Bone cross-sectional areas (CSA), volumes (Vol), and cross-sectional moments of inertia (CSMI) were assessed by magnetic resonance imaging (MRI), and cortical volumetric bone density (volBMD) was determined as the quotient of DXA-derived bone mineral content (BMC) and MRI-derived cortical bone volume. Bone strength index (BSI) was calculated as the product of cortical volBMD and CSMI.

Fracture toughness of bovine bone: influence of orientation and storage media.

Using the single-edge notched bending (SENB) test, two fracture toughness parameters of longitudinal and transverse bovine bone specimens were evaluated: the critical stress intensity factor, Kc, determined from the peak load to initiate fracture, and the energy or work of fracture, Wf, the energy required to extend a crack through a notched specimen. It was found that preservation of bone in alcohol resulted in a 25-45% higher Kc value compared to control specimens stored in physiological saline; whereas the work of fracture, Wf, demonstrated the opposite behaviour, with the alcohol stored specimens having a 28-56% lower value than the saline control specimens. It was established that the effect of alcohol is reversible upon the bone being restored in saline.

A simple method of determining the modulus of orthopedic bone cement.

Accurate determination of the elastic modulus of surgical bone cements is of primary importance, when evaluating the stresses within the cement mantle in Total Joint Arthroplasty. This article presents a new method of determining the modulus of surgical bone cements from the biaxial flexural test. The biaxial flexural test is not currently employed in mainstream orthopedic mechanical testing, which is surprising because most loading in orthopedic applications is biaxial in nature.

The statistical big bang of 1911: ideology, technological innovation and the production of medical statistics.

This paper examines the relationship between intellectual debate, technologies for analysing information, and the production of statistics in the General Register Office (GRO) in London in the early twentieth century. It argues that controversy between eugenicists and public health officials respecting the cause and effect of class-specific variations in fertility led to the introduction of questions in the 1911 census on marital fertility. The increasing complexity of the census necessitated a shift from manual to mechanised forms of data processing within the GRO.

Experimental barbiturate intoxication: treatment by partial cardiopulmonary bypass and hemodialysis.

1. The results of a series of experiments in which anesthetized mongrel dogs were instrumented and preparations for closed-chest partial cardiopulmonary bypass with membrane oxygenation and hemodialysis were made, following which "fatal" barbiturate intoxication was produced by the intravenous route has been presented. 2.