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Biomedical subjects

M R Barnes

Publications and source records attributed to M R Barnes.

At least 19 recordsLinked to original sources
PubMed2000

A comparison of 2 modern femoral cementing techniques: analysis by cement-bone interface pressure measurements, computerized image analysis, and static mechanical testing.

Modern cementing techniques aim to improve microinterlock and to reduce aseptic loosening. The Norwegian and Swedish Arthroplasty Registers have shown an increased risk of revision using reduced-viscosity cement. We have compared 2 modern cementing techniques using retrograde insertion of normal-viscosity and reduced-viscosity cements. Laboratory-simulated arthroplasty was performed in paired human femora. Performance was evaluated by measuring pressures generated during cementation, cement penetration, and shear strength of the prosthesis-cement and bone-cement interfaces. Large differences exist between these 2 modern techniques. Despite no statistical differences between the pressure measurements with the 2 techniques, greater penetration of reduced-viscosity cement was found proximally, with a trend toward increased penetration of the more viscous cement distally. Areas of greater cement penetration with reduced-viscosity cement proximally produced higher values of ultimate shear strength. Both techniques showed a progressive increase in the shear strength as the level of the section progressed toward the tip of the prosthesis. There is a trend with both techniques for the distal fixation to be stronger.

Arthroplasty, Replacement, Hip↗
PubMed2000

Cloning and characterisation of ITGAV, the genomic sequence for human cell adhesion protein (vitronectin) receptor alpha subunit, CD51.

The integrin family of receptors serves as major receptors for extracellular matrix-mediated cell adhesion and migration, cytoskeletal organisation, cell proliferation, survival, and differentiation. The alpha-V integrins consist of a subset which share a common alpha-V subunit combined with one of five beta subunits (beta-1, 3, 5, 6, or 8). The alpha-V integrins have been implicated in a number of developmental processes, including vasculogenesis and angiogenesis, and are therapeutic targets for inhibition of angiogenesis and osteoporosis. The human cDNA for alpha-V integrin (ITGAV) consists of a 5,717-bp transcript with a coding sequence (CDS) of 3,146 bp encoding a 150-kDa mature peptide. Here we describe the gene structure of ITGAV.

Antigens, CD↗
PubMed1999

Identification of a novel mutation R42P in the gap junction protein beta-3 associated with autosomal dominant erythrokeratoderma variabilis.

We report a missense mutation in the gap junction protein beta-3 (encoding Connexin 31), which was detected in only the affected members of a family in which the autosomal dominant skin disease erythrokeratoderma variabilis was segregating. The nucleotide change results in an arginine to proline substitution in codon 42. This residue is positioned on the first transmembrane/first extracellular domain of the gap junction protein with the mutation replacing a negatively charged residue with a nonpolar residue. This change may disrupt the conformation of the protein and voltage gating polarity leading to impaired channel function.

Connexins↗
PubMed1999

Effective audit trails--a taxonomy for determination of information requirements.

Current methods of detecting confidentiality breaches in electronic medical record systems are inadequate, partially due to the lack of necessary information at the point of audit trail analysis. In order to determine the information requirements for effective audit trail analysis, we have formulated a taxonomy of confidentiality breaches. By considering scenarios in which an inappropriate access might occur, we have identified "indicators" of confidentiality breaches, which may be thought of as evidence suggesting the possibility that a confidentiality breach has occurred. The collection of facts needed to describe the indicators provides insight into the types of information needed to improve confidentiality breach detection. Much of the information needed is unlikely to be available in the patient record. Research is needed exploring means of collecting and utilizing information from sources other than the patient record for use in improving patient information security.

Computer Security↗
PubMed1999

Using external data sources to improve audit trail analysis.

Audit trail analysis is the primary means of detection of inappropriate use of the medical record. While audit logs contain large amounts of information, the information required to determine useful user-patient relationships is often not present. Adequate information isn't present because most audit trail analysis systems rely on the limited information available within the medical record system. We report a feature of the STAR (System for Text Archive and Retrieval) audit analysis system where information available in the medical record is augmented with external information sources such as: database sources, Light-weight Directory Access Protocol (LDAP) server sources, and World Wide Web (WWW) database sources. We discuss several issues that arise when combining the information from each of these disparate information sources. Furthermore, we explain how the enhanced person specific information obtained can be used to determine user-patient relationships that might signify a motive for inappropriately accessing a patient's medical record.

Computer Security↗
PubMed1998

Large scale database scrubbing using object oriented software components.

Now that case managers, quality improvement teams, and researchers use medical databases extensively, the ability to share and disseminate such databases while maintaining patient confidentiality is paramount. A process called scrubbing addresses this problem by removing personally identifying information while keeping the integrity of the medical information intact. Scrubbing entire databases, containing multiple tables, requires that the implicit relationships between data elements in different tables of the database be maintained. To address this issue we developed DBScrub, a Java program that interfaces with any JDBC compliant database and scrubs the database while maintaining the implicit relationships within it. DBScrub uses a small number of highly configurable object-oriented software components to carry out the scrubbing. We describe the structure of these software components and how they maintain the implicit relationships within the database.

Confidentiality↗
PubMed1997

A 3-(3-hydroxyphenyl)propionic acid catabolic pathway in Rhodococcus globerulus PWD1: cloning and characterization of the hpp operon.

Rhodococcus globerulus PWD1, a soil isolate from a polluted site in The Netherlands, is able to degrade a broad range of aromatic compounds. A novel gene cluster which appears to encode a pathway for the degradation of phenolic acids such as 3-(3-hydroxyphenyl)propionate (3HPP) has been cloned from the chromosome of this organism. Sequence analysis of a 7-kb region identified five open reading frames (ORFs). Analysis of mRNA showed that the genes were expressed during growth on 3HPP and 3-hydroxyphenylacetate (3HPA) but not during growth on m-cresol or succinate. The first ORF, hppA, which appears to be separately transcribed, had considerable amino acid identity with a number of hydroxylases. Transcriptional analysis indicates that the next four ORFs, hppCBKR, which are tightly clustered, constitute a single operon. These genes appear to encode a hydroxymuconic semialdehyde hydrolase (HppC), an extradiol dioxygenase (HppB), a membrane transport protein (HppK), and a member of the IclR family of regulatory proteins (HppR). The activities of HppB and HppC have been confirmed by enzyme assay of Escherichia coli hosts. The substrate specificity of HppB expressed from the cloned gene matches that of the meta-cleavage dioxygenase expressed from wild-type Rhodococcus grown on both 3HPP and 3HPA and is considerably more active against acid than against neutral catechols. The deduced amino acid sequences of the gene products have a recognizable homology with a broad range of enzymes and proteins involved in biodegradation and appear most similar to the mhp operon from E. coli K-12, which also encodes the degradation of 3HPP.

Bacterial Proteins↗
PubMed1997

Cement pressurisation during hip replacement.

The newer techniques of cementing aim to improve interlock between cement and bone around a femoral stem by combining high pressure and reduced viscosity. This may produce increased embolisation of fat and marrow leading to hypotension, impaired pulmonary gas exchange and death. For this reason the use of high pressures has been questioned. We compared finger-packing with the use of a cement gun by measuring intramedullary pressures during the cementing of 31 total hip replacements and measuring physiological changes in 19 patients. We also measured pressure in more detail in a laboratory model. In the clinical series the higher pressures were produced by using a gun, but this caused less physiological disturbance than finger-packing. The laboratory studies showed more consistent results with the gun technique, but for both methods of cementing the highest pressures were generated during the insertion of the stem of the prosthesis.

Bone Cements↗
PubMed1995

Reduction of temperatures generated by the triple reamer within the femoral head.

The triple reamer is a convenient tool for reaming the proximal femur when using a sliding screw and plate device, but unnecessarily high temperatures may be generated within the femoral head while the lateral cortex is being reamed. Nineteen female patients over 60 years old were randomized to either the standard or a modified reaming technique with the triple reamer during internal fixation of proximal femoral fractures. Temperatures generated within the femoral head were measured. Results showed a mean peak temperature of 51.9 degrees C (range 42-66) using the standard method and 46.3 degrees C (range 40-52) using the modified method (P = 0.07). A significant difference (P < 0.05) was found in the duration of temperature elevation above the critical 44 degrees C (17.4s vs 5.7s), it being prolonged in the standard group. Even in this osteoporotic patient group, damaging temperatures which may contribute to the mechanical failure of fixation, are generated within the femoral head. A simple method to avoid this problem is described.

Female↗
PubMed1995

The value of 99Tcm-MDP bone scans in young patients with exercise-induced lower leg pain.

This study compares the bone scan appearances in 32 patients with medial tibial syndrome (MTS) with the appearance in 28 patients with confirmed chronic compartment syndrome (CCS). A distinctive pattern of uptake was seen in 30 patients, 24 of whom had MTS and 6 of whom had CCS. Of the patients with normal scans, only 4 had MTS, the remaining 15 had CCS. Both of these findings are statistically significant and confirm that bone scans are a useful diagnostic tool in the differential diagnosis of exercise-induced lower leg pain.

Adult↗
PubMed1993

Popliteal entrapment syndrome: misdiagnosed as a compartment syndrome.

We report a case of popliteal artery entrapment syndrome which was originally diagnosed as a chronic compartment syndrome. The relative occurrence of the two conditions and their very similar symptoms explain the misdiagnosis. The diagnostic methods and surgical treatment for both conditions are discussed and suggestions are made as to possible non-invasive screening methods.

Adult↗