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Biomedical subjects

R Marshall

Publications and source records attributed to R Marshall.

At least 19 recordsLinked to original sources
PubMed2007

Characteristics of the m2000 automated sample preparation and multiplex real-time PCR system for detection of Chlamydia trachomatis and Neisseria gonorrhoeae.

We evaluated a new real-time PCR-based prototype assay for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae developed by Abbott Molecular Inc. This assay is designed to be performed on an Abbott m2000 real-time instrument system, which consists of an m2000sp instrument for sample preparation and an m2000rt instrument for real-time PCR amplification and detection. The limit of detection of this prototype assay was determined to be 20 copies of target DNA for both C. trachomatis and N. gonorrhoeae, using serially diluted linearized plasmids. No cross-reactivity could be detected when 55 nongonococcal Neisseria isolates and 3 non-C. trachomatis Chlamydia isolates were tested at 1 million genome equivalents per reaction. Concordance with the Roche Amplicor, BDProbeTec ET, and Gen-Probe APTIMA Combo 2 tests was assessed using unlinked/deidentified surplus clinical specimens previously analyzed with these tests. For C. trachomatis, concordance for positive results ranged from 93.7% to 100%, while concordance for negative results ranged from 98.2% to 100%. For N. gonorrhoeae, concordance for positive and negative results ranged from 91.4% to 100% and 99.3% to 100%, respectively. A workflow analysis of the prototype assay was conducted to obtain information on throughput under laboratory conditions. At 48 samples/run, the time to first result for both C. trachomatis and N. gonorrhoeae was 4.5 h. A total of 135 patient specimens could be analyzed in 8.9 h, with 75 min of hands-on time. This study demonstrated the technical and clinical feasibility of the new Abbott real-time PCR C. trachomatis/N. gonorrhoeae assay.

Automation↗
PubMed2007

Artificial neural network: predicted vs observed survival in patients with colonic cancer.

PURPOSE: An Internet-web-based artificial neural network has been developed for practicing clinical oncologists and medical researchers as part of an ongoing program designed for the implementation of advanced neural networks for prognostic estimates and eventually for management/treatment decisions in individual patients with colonic cancer. METHODS: An interdisciplinary team of academic oncologists and physicists has configured and implemented a Partial Logistic Artificial Neural Network and trained it to predict cancer-related survival in patients with confirmed colorectal cancer by using a database (1,558 patients) made available for the study by the Information & Statistics Division of National Health Service Scotland. The reliability of the trained network was evaluated against Kaplan-Meier observed survival plots of a random sample of 300 patients not used in the training but forming part of the same data set. RESULTS: The predicted survival curves obtained as the output from the artificial neural network showed close agreement with observed actual survival rates of a cohort of 300 patients with four grades of risk of dying from the cancer within five years of diagnosis. CONCLUSIONS: The web-based Partial Logistic Artificial Neural Network system accurately predicts survival after staging and treatment of colonic cancer. It can be made web-accessible where it is powerful enough to serve hundreds of users simultaneously.

Aged↗
PubMed2006

Physiological effects of lower extremity functional electrical stimulation in early spinal cord injury: lack of efficacy to prevent bone loss.

STUDY DESIGN: Controlled, repeat-measures study. OBJECTIVES: To determine if functional electrical stimulation (FES) can affect bone atrophy in early spinal cord injury (SCI), and the safety, tolerance and feasibility of this modality in bone loss remediation. SETTING: Spinal Injuries Units, Royal Adelaide Hospital and Hampstead Rehabilitation Centre, South Australia. METHODS: Patients with acute SCI (ASIA A-D) were allocated to FES (n=23, 28+/-9 years, C4-T10, 13 Tetra) and control groups (CON, n=10, 31+/-11 years, C5-T12, four Tetra). The intervention group received discontinuous FES to lower limb muscles (15 min sessions to each leg twice daily, over a 5-day week, for 5 months). Dual energy X-ray absorptiometry (DEXA) measured total body bone mineral density (tbBMD), hip, spine BMD and fat mass (FM) within 3 weeks, and 3 and 6 months postinjury. RESULTS: FES and CON groups' tbBMD differed significantly at 3 months postinjury (P<0.01), but not thereafter. Other DEXA measures (hip, spine BMD, FM) did not differ between groups at any time. No adverse events were identified. CONCLUSION: Electrically stimulated muscle activation was elicited, and tetanic effects were reproducible; however, there were no convincing trends to suggest that FES can play a clinically relevant role in osteoporosis prevention (or subsequent fracture risk) in the recently injured patient. The lack of an osteogenic response in paralysed extremities to electrically evoked exercise during subacute and rehabilitation/recovery phases cannot be fully explained, and may warrant further evaluation.

Adipose Tissue↗
PubMed2006

EpCAM and gpA33 are markers of Barrett's metaplasia.

AIMS: To characterise a specific and sensitive marker of Barrett's metaplasia (BM). METHODS: Cases of normal oesophageal squamous mucosa (11 fresh endoscopic biopsies and 10 formalin fixed, paraffin embedded tissue blocks), BM (11 biopsies and 11 tissue blocks), and normal gastric body mucosa (five biopsies and five tissue blocks) were analysed using reverse transcriptase PCR, Western blotting, and immunohistochemistry for EpCAM, and reverse transcriptase PCR for gpA33. RESULTS: Strong EpCAM mRNA expression was detected in all the BM cases, in contrast to weak expression in all the normal gastric mucosal samples and no expression in any of the normal oesophageal mucosal samples tested. Strong gpA33 mRNA expression was detected in all the BM cases, in contrast to weak expression in a quarter of the normal gastric mucosal samples and no expression in any of the normal oesophageal mucosal samples tested. Western blotting showed EpCAM protein expression in all the BM cases and in none of the normal gastric or oesophageal mucosal samples tested. Immunohistochemistry showed strong EpCAM protein expression in BM and complete absence of expression in normal oesophageal squamous epithelium. Scattered EpCAM expressing cells were found in the gland bases of normal gastric body mucosa. CONCLUSIONS: EpCAM protein and gpA33 mRNA expressions are specific and sensitive markers of BM.

Antigens, Neoplasm↗
PubMed2006

Conservation of Pitx1 expression during amphibian limb morphogenesis.

In contrast to the pattern of limb emergence in mammals, chicks, and the newt N. viridescens, embryos such as Xenopus laevis and Eleutherodactylus coqui initiate pelvic limb buds before they develop pectoral ones. We studied the expression of Pitx1 in X. laevis and E. coqui to determine if this paired-like homeodomain transcription factor directs differentiation specifically of the hindlimb, or if it directs the second pair of limbs to form, namely the forelimbs. We also undertook to determine if embryonic expression patterns were recapitulated during the regeneration of an amputated limb bud. Pitx1 is expressed in hindlimbs in both X. laevis and E. coqui, and expression is similar in both developing and regenerating limb buds. Expression in hindlimbs is restricted to regions of proliferating mesenchyme.

Animals↗
PubMed2005

CDX1 is an important molecular mediator of Barrett's metaplasia.

The molecular pathogenesis of Barrett's metaplasia (BM) of the esophagus is poorly understood. The change to an intestinal phenotype occurs on a background of esophagitis due to refluxing acid and bile. CDX1, an important regulator of normal intestinal development, was studied as a potential key molecule in the pathogenesis of BM. CDX1 mRNA and protein were universally expressed in all samples of BM tested but not in normal esophageal squamous or gastric body epithelia. This tissue-specific expression was attributable to the methylation status of the CDX1 promoter. Conjugated bile salts and the inflammatory cytokines TNF-alpha and IL-1beta were all found to increase CDX1 mRNA expression in vitro. These effects were primarily mediated by NF-kappaB signaling but only occurred when the CDX1 promoter was unmethylated or partially methylated. The data suggest that CDX1 is a key molecule linking etiological agents of BM to the development of an intestinal phenotype. Although the initial trigger for CDX1 promoter demethylation is not yet identified, it seems likely that demethylation of its promoter may be the key to the induction and maintenance of CDX1 expression and so of the BM phenotype.

Barrett Esophagus↗
PubMed2004

Evaluation of an electronic general-practitioner-based syndromic surveillance system--Auckland, New Zealand, 2000-2001.

INTRODUCTION: During 2000 and 2001, Auckland Regional Public Health Service piloted a general-practitioner-based syndromic surveillance system (GPSURV). OBJECTIVES: The pilot evaluated data capture, the method used to distinguish initial from follow-up visits, the definition of denominators, and the external validity of measured influenza-like illness trends. METHODS: GPSURV monitored three acute infectious-disease syndromes: gastroenteritis, influenza-like illness, and skin and subcutaneous tissue infection. Standardized terms were used to describe the syndromes. Data were uploaded daily from clinics and transferred to a database via a secure network after one-way encryption of patient identifiers. Records were matched to allow the distinction of follow-ups from first visits, based on between-visit intervals of </=8 weeks. Denominator populations were based on counts of unique patients treated at participating clinics during the previous 2 years. Record completion was examined by using before-and-after surveys of self-assessed standardized-term recording. Between-visit intervals were counted for matching records and alternative denominators were calculated on the basis of different observation periods. Weekly influenza-like illness rates were compared with rates generated by an alternative system. RESULTS: Physicians' self-reported recording compliance was highest for skin and subcutaneous tissue infection (71%) and lowest for influenza-like illness (48%). Initial visits had 18%-19% greater compliance than follow-up visits. The number of physicians reporting increasing compliance during the pilot was greater than the number reporting decreases for all conditions. Comparison of data with an independent influenza-like illness surveillance system indicated a close agreement between the two data series. CONCLUSIONS: These results indicate that incidence of acute syndromes can be monitored, at least as successfully as a manual system, by using standardized clinical-term data from selected general-practice clinics. The provision of feedback reports appears to have a limited but positive effect on data quality.

Disease Outbreaks↗
PubMed2004

Representing older and disabled people in virtual user trials: data collection methods.

A database was developed to support the creation of a computer-based tool which will support design teams in evaluating the usability of a design during early prototyping and indicate which individuals are effectively excluded or designed out. Methods are described for the collection of multivariate data on 100 real individuals covering a range of physical characteristics and capabilities. These data were tested to ensure a breadth of representation of individuals (particularly older and disabled people) in terms of anthropometry, joint constraints, postural capabilities and task behaviours. The concept of the design tool itself is explored by conducting virtual user trials in the computer-aided design environment. The novel approach of the research encourages empathy with individual users and allows generic abilities, such as bending, reaching and lifting to be assessed.

Adolescent↗
PubMed2003

Chromosomal aberration frequencies in patients with thalassaemia major undergoing therapy with deferiprone and deferoxamine in a comparative crossover study.

Measurements of chromosomal aberrations were made in 10 thalassaemia major patients treated long-term with deferiprone (at least 5 years) and compared with an equal number of patients matched for age, sex and iron overload, treated long-term with deferoxamine. Two blood samples were collected from each patient, 7 and 20 days after a transfusion episode, and the frequency of chromosomal aberrations (gaps, breaks and exchanges) in the patients' circulating lymphocytes analysed in both samples using standard cytogenetic staining techniques. The frequency of reciprocal translocations was also analysed using fluorescence in situ hybridization. Relatively low frequencies of cells with stable and unstable aberrations were seen at both sampling times in all patients, with no statistically significant differences between sexes. Chromosomal aberrations were less frequent in patients treated long-term with deferiprone than in patients treated with deferoxamine, although the difference did not reach statistical significance. After the second blood sample had been collected, all patients had their iron chelation therapy switched to the other chelator. Patients treated long-term with deferiprone had their therapy switched to deferoxamine and patients treated long-term with deferoxamine had their therapy switched to deferiprone. After the switch, two further blood samples were collected 7 and 20 days after transfusion for each of the next two transfusion cycles in all patients. Analysis of the post-switch samples also revealed a slightly higher frequency of chromosomal aberrations during therapy with deferoxamine than with deferiprone at all time points. A small, but statistically significant, increase in cells with aberrations was observed at the first post-switch assessment in the group of patients whose therapy was switched from deferiprone to deferoxamine, whereas the switch from deferoxamine to deferiprone was associated with a decrease in the frequency of chromosomal aberrations. The results of the study demonstrate that, in a clinical setting, deferiprone has no greater clastogenic activity than that of deferoxamine.

Adolescent↗
PubMed2001

Evaluation of the rodent micronucleus assay by a 28-day treatment protocol: Summary of the 13th Collaborative Study by the Collaborative Study Group for the Micronucleus Test (CSGMT)/Environmental Mutagen Society of Japan (JEMS)-Mammalian Mutagenicity Study Group (MMS).

To examine whether micronucleus tests can be incorporated into general toxicology assays, we performed micronucleus tests applying the treatment protocols typically used in such assays. In this 13th Collaborative Study of the CSGMT, both rats and mice were tested, although rats were used in the majority of the studies. Fifteen mutagens were tested in rats, mainly by oral (p.o.) administration. Micronucleus induction was evaluated 2, 3, and 4 days, and 1, 2, 3, and 28 days after the beginning of the treatment in the peripheral blood, and at 28 days in the bone marrow. Of the 15 chemicals that induced micronuclei in rats in short-term assays, two chemicals (1,2-dimethylhydrazine.2HCl and mitomycin C) were negative in all our experiments, possibly because of insufficient dose levels. The remaining 13 were positive within the estimated dose range of a general toxicology assay, suggesting the possibility of integrating the micronucleus assay into general toxicology assays. Three patterns were observed in micronucleus induction during the period of repeated treatment: (1) gradual increases in micronucleus frequency with sequential doses, (2) a peak at 3-5 days followed by gradual decreases in micronucleus frequency with sequential doses, and (3) a rapid increase in micronucleus frequency followed by a plateau. We evaluated factors that might have been involved in those patterns, such as the spleen function, target organ exposure, extramedullary hematopoiesis, hypothermia, and hypoxia. Another factor we considered was dosage. Because the dosages employed in a general toxicity assay are usually lower than those used in short-term micronucleus assays, this discrepancy was considered the greatest potential problem for integrating the micronucleus assay into general toxicology assays. Our results indicate that the integration of the micronucleus assay into a 28-day toxicological assay is feasible. To serve this purpose, blood samples collected 4 days after the beginning of treatment and blood and bone marrow samples collected at autopsy should be examined. Furthermore, although it is recognized that mice may be suitable for performing independent micronucleus assays, we propose that rats can provide biologically important and relevant information regarding potential chemical mutagens that can be evaluated under conditions used in the conduct of general toxicology studies.

Animals↗
PubMed2001

Postgraduate year does not influence operating time in laparoscopic cholecystectomy.

BACKGROUND: Surgical resident education may contribute to increased operating time, thus increasing costs at teaching institutions. It is possible that junior residents, in particular, with less experience could contribute to longer operating times for laparoscopic cholecystectomy. We hypothesized that all general surgery residents, regardless of level of training and with proper supervision, could complete a laparoscopic cholecystectomy in a safe and timely fashion. MATERIALS AND METHODS: A retrospective study was performed using data collected from laparoscopic cholecystectomies completed under the supervision of one attending surgeon over a 2-year period. Operating times were recorded, the operating surgeon was identified, and cases were assigned an acuity level based on pathologic findings. Operative times were compared after dividing surgeons into three groups (junior residents, senior residents, and staff). RESULTS: Seventy-one cases were entered into the study. There were no differences when comparing mean operating times among the three groups (P = 0.2, analysis of variance). The pathologic acuity in each group was similar (P = 0.8, Fisher's exact test). There was a difference when evaluating the operating times for the pathologic level of acuity (P = 0.002, Kruskal-Wallis test). CONCLUSIONS: Resident level does not affect the operating time in performing laparoscopic cholecystectomy. The pathologic acuity of the gallbladders was distributed similarly for all three groups. There was a difference in mean operating time based on pathologic acuity. Laparoscopic cholecystectomy can be performed in a safe and efficient manner at a teaching institution.

Acute Disease↗
PubMed2001

Strategic management simulations is a novel way to measure resident competencies.

BACKGROUND: The Strategic Management Simulation (SMS) has been used extensively to test and train higher cognitive functions in persons who occupy professional and leadership positions (i.e., skills like those needed by a surgeon). METHODS: The SMS was used to predict surgical residents' competency in decision making. Skills required for integrative surgical decision making including critical thinking, crisis management, flexibility, factual knowledge, and team building were assessed. Surgical residents with at least 2 years of experience participated. In additional, attending faculty familiar with the residents' work evaluated each resident with a standard comprehensive rating scale. Simulation performance on multiple measures was compared with faculty ratings. RESULTS: A number of measures obtained on simulation performance (eg, activity level, response speed, initiative, adequate usage of and appropriate search for relevant information) generated high correlations with comprehensive faculty assessment (eg, measures of crisis management, team interactions, flexibility of approach). CONCLUSION: The simulation technique is able to accurately assess performance of surgical residents (on a number of parameters) in a relatively brief time period. Simulation data were highly similar to faculty ratings that were based on at least 2 years of experience with the resident.

Clinical Competence↗
PubMed2001

Bacterial contamination of uniforms.

Microbiological sampling of nurses' uniforms was undertaken using a Casella slit sampler. Staphylococcus aureus, Clostridium difficile and vancomycin-resistant enterococci were detected on uniforms both before and after a span of duty. Recommendations for provision and changing of nurses' uniforms are made.

Clostridioides difficile↗
PubMed2001

Are survey measures of medical care utilisation misleading? A comparison of self-reported medical care consumption with actual medical care utilisation.

A substantial over-estimate of medical care consumption cost was found when estimates from self-report data from an epidemiological study were compared to actual cost data extracted from administrative records. Even though the few subjects who were actually provided with two or more services in the two-week self-report period substantially under-reported their medical care consumption, a large net over-estimate of medical care consumption was produced by the self-report data. This finding has important implications for use of self-report data from surveys such as the Australian Bureau of Statistics (ABS) National Health Survey for estimating health service consumption. By combining epidemiological survey data from the Australian Vietnam Veterans Health Study (AVVHS), with data on actual medical care for which the Health Insurance Commission (HIC) or the Department of Veterans' Affairs (DVA) paid benefits, we were able to directly compare self-reported medical care consumption with actual medical care utilisation. The comparison revealed that veterans' self-reports were a valid measure of relative medical care consumption because those who reported care over the past two weeks were much more likely to have been recent consumers than those who did not. This relationship became even stronger if the comparison of self-report was extended to data on benefits paid beyond the two-week self-report period. However, the HIC and DVA data confirmed only 51% of veterans self-reporting medical care consumption during the past two weeks actually received a service.

Health Care Surveys↗
PubMed2001

Assessing the subjective experience of being a participant in psychiatric research.

OBJECTIVE: To address both clinical and ethical concerns in psychiatric research, the study assessed the subjective experience of being a participant in a feasibility study of outcome in long-term psychodynamic psychotherapy and psychoanalysis. METHOD: A questionnaire assessing positive and negative reactions to three typical research methodologies (self-report questionnaires, structured diagnostic interviews, and tape-recording of sessions) was administered to 23 patient-therapist pairs. RESULTS: Patients reported that questionnaires and interviews were slightly to moderately helpful in promoting self-realization and facilitating therapy, and not at all to slightly intrusive and disruptive. Adjustment to audiotaping of sessions was rapid (within two sessions). Therapists significantly overestimated the negative effects and underestimated the positive benefit patients reported from participating in research. CONCLUSIONS: Traditional objections to research in dynamic psychotherapy on the grounds that patients experience research procedures as significantly intrusive and disruptive appear to be unfounded.

Adult↗
PubMed2000

4SR, a novel zinc-finger protein with SR-repeats, is expressed during early development of Xenopus.

The protein C4SR contains two cysteine(4) (C(4)) zinc-finger motifs at its amino terminus, a stretch of acidic residues in the middle and a series of serine-arginine (SR) repeats at its carboxyl terminus. A cDNA clone encoding the zinc-finger domain was first selected from a Xenopus laevis oocyte expression library on the basis of the ability of the fusion protein to stably bind an RNA probe. The mRNA encoding C4SR is expressed during oogenesis, and the protein is present at a constant level in oocytes and early embryos. The C4SR protein is expressed in transcriptionally active erythroblasts but not in transcriptionally inert mature erythrocytes. An epitope-tagged C4SR protein, expressed in oocytes, associates with nascent transcripts at many loci in lampbrush chromosomes and is absent from storage particles (snurposomes) containing the normally recognized complement of RNA splicing components. It is likely that C4SR is involved in pre-mRNA transcription/packaging rather than in exon splicing. The zinc-finger motif, present as two copies in C4SR, is also present in a range of transcription-associated proteins. We suggest the descriptor (DW)C(4), in which DW refers to the invariant aspartic acid (D)/tryptophan (W) dipeptide that precedes the first cysteine residue, for this distinctive zinc-finger structure.

Amino Acid Sequence↗