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Biomedical subjects

J R Clarke

Publications and source records attributed to J R Clarke.

At least 37 records · Page 2Linked to original sources
PubMed1999

The growth and the control of human immunodeficiency virus in the lung: implications for highly active antiretroviral therapy.

In recent years, it has become apparent that the lung is an important niche for the proliferation of human immunodeficiency virus (HIV), which may have implications for highly active antiretroviral therapy (HAART). The lung itself is a major site for the opportunistic infections associated with the progression to acquired immune deficiency syndrome (AIDS), specifically Pneumocystis carinii, Myobacterium tuberculosis and pyogenic bacteria. These cases of active pulmonary complications are direct indicators of enhanced progression to AIDS-defining illness and increased morbidity and mortality. It is therefore essential that the interaction between the lung and HIV is fully understood. Recent research indicates the lung may be a major sanctuary for the virus, with distinct evolution and replication in contrast to other target organs for HIV. In this review, we will discuss the recent findings of HIV infection, evolution, host factors involved in the control of HIV within the lung and the impact this may have on current therapy.

AIDS-Related Opportunistic Infections↗
PubMed1999

Granulated metrial gland cells and interstitial trophoblast in the uterine wall of the bank vole, Clethrionomys glareolus, in early pregnancy.

The morphology and distribution of granulated metrial gland cells and of interstitial trophoblast cells in the uterine wall was studied in the first half of pregnancy in the bank vole, Clethrionomys glareolus. The morphology and distribution of granulated metrial gland cells was generally similar to that found in other members of the Rodentia, although they were absent from the walls of the arterial vessels passing through the decidua basalis. Interstitial trophoblast invaded the decidualising endometrium mesometrial to, and antimesometrial to, the implanted embryos. There was no apparent spatiotemporal relationship between the distribution of granulated metrial gland cells and interstitial trophoblast cells.

Animals↗
PubMed1999

Spontaneous rupture of the diaphragm.

A 2.5 year old girl with metachromatic leukodystrophy presented with acute respiratory distress and was initially wrongly diagnosed with pneumothorax. Barium meal showed bowel loops in the left hemithorax, which prompted surgical intervention; spontaneous rupture of the diaphragm was diagnosed at surgery.

Child, Preschool↗
PubMed1999

Assessment of oxygen levels in alternative designs of semiclosed underwater breathing apparatus.

A method for predicting the circuit oxygen levels in semiclosed underwater breathing apparatus (UBAs) is presented. Oxygen levels are assessed for traditional circuit designs using sonic metering valves to inject a constant mass flow of fresh makeup as well as two alternative respiration-rate-coupled gas dosage designs using demand injection valves. The impact of variations in diver depth, activity level, gas injection rate, circuit volume, and makeup gas composition on these circuit oxygen levels is demonstrated. Respiration-coupled, demand gas delivery systems are shown to have significantly reduced circuit oxygen variations over a wide range of diver activity levels when compared to constant mass flow injection systems. Additionally, the respiration-coupled designs are shown to have potential reduced gas usage at low diver activity levels, resulting in longer mission duration capability, when compared to constant mass injection systems.

Atmospheric Pressure↗
PubMed1998

A comparison of the social backgrounds and dental health of patients attending the Community Dental Service, the General Dental Service and non registered patients.

OBJECTIVE: To compare the dental health and social backgrounds of children in Southern Birmingham registered with the General Dental Service (GDS), the Community Dental Service (CDS) and those who were not registered with a dentist. DESIGN: Data characterising children as either registered with the GDS or not registered, which had been collected for a study in 1993/4 were analysed to distinguish those children attending the CDS within Southern Birmingham. The children were divided into three groups; those registered with the GDS, those attending the CDS and those not registered with a dentist. SUBJECTS: Three thousand two hundred and five eight-year-old children who attended schools in Southern Birmingham. RESULTS: Of the children attending the CDS 74% were in the lowest ACORN category compared with 44% of those registered with GDS. Only 10% of the children registered with the GDS were of Asian ethnic origin compared with 54% of those attending the CDS. The dmft of children from the same ethnic background and ACORN category was found to be higher in those children registered with the GDS (3.15 +/- 2.75) than those who were not registered (2.17 +/- 2.58), due to more filled and missing teeth. CONCLUSIONS: A higher proportion of children attending the CDS in Southern Birmingham come from a deprived social background and are of Asian ethnic origin than those registered with the GDS. The dental health of these children differs between those who have attended a dentist (GDS or CDS) and those who are non-registered (P < 0.05).

Child↗
PubMed1997

What predicts gastroenterologists' and surgeons' diagnosis and management of common bile duct stones?

BACKGROUND: Because the literature suggests numerous indicators of common bile duct stones, we undertook a systematic assessment of physicians' judgments of the clinical utility of eight indicators: patient age, history of jaundice, history of pancreatitis, levels of serum alanine aminotransferase, alkaline phosphatase, amylase, and total bilirubin, and common bile duct diameter on ultrasonography. METHODS: Random samples of 1500 gastroenterologists and 1500 surgeons were sent a survey asking them to indicate the importance of each potential indicator of common bile duct stones, the likelihood of common bile duct stones for each of nine clinical vignettes, and whether they would order a preoperative ERCP. An abbreviated survey was sent to nonrespondents. RESULTS: Although there was substantial variation in the importances assigned to each indicator, the most important indicators were serum total bilirubin and diameter of common bile duct on ultrasound. The best predictors of the decision to order an ERCP were perceived likelihood of stones and specialty. The average threshold for ordering an ERCP was 37%. Respondents did not differ from nonrespondents in the perceived importance of the eight indicators. CONCLUSIONS: The substantial variation among gastroenterologists and surgeons regarding the optimal approach to common bile duct stones has clinical implications. Patients will receive varying recommendations for care, depending on whom they see.

Adult↗
PubMed1997

On-line quality [corrected] assurance in the initial definitive management of multiple trauma: evaluating system potential.

The TraumAID system has been designed to provide on-line decision support throughout the initial definitive management of injured patients. Here we describe its retrospective evaluation and the use we subsequently made of judges comments on the validation data to evaluate TraumaTIQ, a new critiquing interface for TraumAID, investigating the question of whether, with timely recording of information, a system could produce commentary in line with that of human experts. Our results show that (1) comparable commentary can be produced, and (2) validation studies, which take great time and effort to conduct, can produce useful data beyond their original design goals.

Evaluation Studies as Topic↗
PubMed1997

Molecular cloning, expression, and characterization of a functional single-chain Fv antibody to the mycotoxin zearalenone.

The heavy-chain and kappa light-chain variable region genes of an antizearalenone hybridoma cell line (2G3-6E3-2E2) were isolated by PCR and joined by a DNA linker encoding peptide (Gly4Ser)3 as a single-chain Fv (scFv) DNA fragment. The scFv DNA fragment was cloned into a phagemid (pCANTAB5E) and expressed as a fusion protein with E tag and phage M13 p3 in Escherichia coli TG1. In the presence of helper phage M13K07, the scFv fusion protein was displayed on the surfaces of recombinant phages. High-affinity scFv phages were enriched through affinity selection in microtiter wells coated with zearalenone-ovalbumin conjugate. The selected recombinant phages were used to infect E. coli HB2151 for the production of soluble scFv antibodies. One selected clone (pQY1.5) in HB2151 secreted a soluble scFv antibody (QY1.5) with a high zearalenone-binding affinity (concentration required for 50% inhibition of binding, 14 ng/ml), similar to that of parent monoclonal antibody in a competitive indirect enzyme-linked immunosorbent assay. However, scFv QY1.5 exhibited higher cross-reactivity with zearalenone analogs and had greater sensitivity to methanol destabilization than the parent monoclonal antibody did. Nucleotide sequence analyses revealed that the light-chain portion of scFv QY1.5 had a nucleotide sequence identity of 97% to a mouse germ line gene VK23.32 in mouse kappa light-chain variable region subgroup V, whereas the heavy-chain nucleotide sequence was classified as mouse heavy-chain subgroup III (D) but without any closely related members having highly homologous complementarity-determining region sequences. The potential of soluble scFv QY1.5 for routine screening of zearalenone and its analogs was demonstrated with zearalenone-spiked corn extracts.

Amino Acid Sequence↗
PubMed1997

Simulated casualties and medics for emergency training.

The MediSim system extends virtual environment technology to allow medical personnel to interact with and train on simulated casualties. The casualty model employs a three-dimensional animated human body that displays appropriate physical and behavioral responses to injury and/or treatment. Medical corpsmen behaviors were developed to allow the actions of simulated medical personnel to conform to both military practice and medical protocols during patient assessment and stabilization. A trainee may initiate medic actions through a mouse and menu interface; a VR interface has also been created by Stansfield's research group at Sandia National Labs.

Computer Simulation↗
PubMed1997

Probabilistic predictions of penetrating injury to anatomic structures.

This paper presents an interactive 3D graphical system which allows the user to visualize different bullet path hypotheses and stab wound paths and computes the probability that an anatomical structure associated with a given penetration path is injured. Probabilities can help to identify those anatomical structures which have potentially critical damage from penetrating trauma and differentiate these from structures that are not seriously injured.

Anatomy, Cross-Sectional↗
PubMed1997

Integrating communicative goals for real-time clinical decision support.

A critiquing system evaluating a physician's management plan may produce a set of individual comments that, taken together, appear repetitious or incoherent. This paper presents TraumaGEN, a system for integrating sets of possibly inter-related communicative goals into one or more coherent messages. TraumaGEN takes account of the purpose of the messages, the situation in which the messages will be received, and the social role of the system. Preliminary evaluation of TraumaGEN indicates that it produce coherent integrated messages.

Communication↗
PubMed1996

Predictors of common bile duct stones prior to cholecystectomy: a meta-analysis.

BACKGROUND: The decision of whether or not to investigate for common bile duct stones before cholecystectomy utilizes clinical, laboratory, and radiologic information (indicators). There is tremendous individual variation among clinicians in the criteria used for making this decision. Our aim was to perform a meta-analysis of published data to estimate the performance characteristics of the most commonly used preoperative indicators of common bile duct stones. METHODS: Using predetermined exclusion criteria, we selected articles from a MEDLINE search and bibliographic review. Weighted averages were used to determine summary sensitivity, specificity, and positive and negative likelihood ratios for each indicator for stones. RESULTS: From 2221 citations identified, 22 studies met inclusion criteria. The 10 indicators examined were reported in a common fashion in three or more articles, and could be assessed preoperatively. Seven exhibited a specificity greater than 90%. Indicators with positive likelihood ratios of 10 or above were cholangitis, preoperative jaundice, and ultrasound evidence of common bile duct stones. Positive likelihood ratios for dilated common bile duct on ultrasound, hyperbilirubinemia, and jaundice ranged from almost 4 to almost 7. Elevated levels of alkaline phosphatase, pancreatitis, cholecystitis, and hyperamylasemia exhibited positive likelihood ratios of less than 3. CONCLUSIONS: This meta-analysis has identified indicators for duct stones and ranked them according to likelihood ratios. These findings can be applied as guidelines for whether to investigate for duct stones before cholecystectomy.

Cholecystectomy↗
PubMed1996

Video assessment of trauma response: adherence to ATLS protocols.

A novel strategy using videotape recordings of initial trauma resuscitations was incorporated into the quality assurance program at a level 1 trauma center. Described are the process of taping the resuscitations, the multidisciplinary nature of the resuscitation team, the security measures taken to assure patient confidentiality, and the review process involved. The videotape review process was incorporated into a multidisciplinary educational trauma conference. The videotapes were used to evaluate the adherence to Advanced Trauma Life Support (ATLS) resuscitation protocols. Resident performance in six aspects of the ATLS resuscitation process were specifically highlighted on each videotape and graded for adherence to preestablished standards. The videotape process allowed an unblased, indisputable accurate documentation of the sequential application of the protocols of evaluation and resuscitation espoused in the ATLS course. We found 23% overall deviation from ATLS resuscitation principles, with at least one aspect of the resuscitation deviating from expected ATLS performance in 64% of the patients. In addition to documenting adherence to ATLS principles, this study illustrated the impact of the videotape review process on the education of eight senior residents in surgery.

Clinical Competence↗
PubMed1996

Validation of questionnaire and bronchial hyperresponsiveness against respiratory physician assessment in the diagnosis of asthma.

BACKGROUND: The Tasmanian Asthma survey (TAS) and the International Study of Asthma and Allergies in Childhood (ISAAC) have used questionnaires to measure the prevalence of asthma in adults and children. We have investigated the validity of these questionnaires by comparing response to questionnaire with a physician assessment of asthma status in the past 12 months. METHODS: Ninety-three adults were given the TAS questionnaire to complete and 361 children were given the ISAAC questionnaire. Ninety-one adults and 168 children completed bronchial challenge with hypertonic saline. A consultation with a respiratory physician blinded to the results of the questionnaire and bronchial challenge was given to all subjects. RESULTS: In both adults and children, questionnaires showed high agreement with respiratory physician diagnosis with respect to asthma symptoms in the past 12 months. For the TAS questionnaire the positive and negative predictive values (95% confidence limits) for physician diagnosis for adults were 0.89 (0.68-0.98) and 0.94 (0. 86-0.98) respectively. The instrument was also sensitive 0.80 (0. 58-0.93) and highly specific 0.97 (0.90-0.99). For the ISAAC questionnaire the positive and negative predictive vales for physician diagnosis of asthma in children were 0.61 (0.50-0.71) and 0.94 (0.88-0.98) respectively. Sensitivity and specificity were 0.85 (0.73-0.93) and 0.81 (0.76-0.86) respectively. Compared to the physician diagnosis, the sensitivity of bronchial hyperresponsiveness (BHR) for asthma was low for adults 0.39 (0.21-0. 61) and children 0.54 (0.48-0.67) as were the positive predictive values: 0.55 (0.31-0.79) for adults and 0.64 (0.449-0.77) for children. A definition of asthma requiring both a positive questionnaire response and BHR was highly specific but not sensitive for adults 0.37 (0.20-0.59) or children 0.47 (0.35-0.60). CONCLUSIONS: Both the TAS and ISAAC questionnaires are valid instruments for the determination of asthma symptoms in the past 12 months.

Adolescent↗
PubMed1996

Mortality and complications associated with laparoscopic cholecystectomy. A meta-analysis.

OBJECTIVE: The purpose of this study was to perform a meta-analysis of large laparoscopic cholecystectomy case-series and compare results concerning complications, particularly bile duct injury, to those reported in open cholecystectomy case-series. SUMMARY BACKGROUND DATA: Since the introduction of laparoscopic cholecystectomy in the United States, hundreds of reports about the technique have been published, many including statements about the advantages of laparoscopic cholecystectomy compared with those of open cholecystectomy. There is an unevenness in scope and quality of the studies. Nevertheless, enough data have accumulated from large series to permit analyses of data regarding some of the most important issues. METHODS: Articles identified via a MEDLINE (the National Library of Medicine's computerized database) search were evaluated according to standard criteria. Data regarding the patient sample, study methods, and outcomes of cholecystectomy were abstracted and summarized across studies. RESULTS: Outcomes of laparoscopic cholecystectomy are examined for 78,747 patients reported on in 98 studies and compared with outcomes of open cholecystectomy for 12,973 patients reported on in 28 studies. Laparoscopic cholecystectomy appears to have a higher common bile duct injury rate and a lower mortality rate. Estimated rates of other types of complications after laparoscopic cholecystectomy generally were low. Most conversions followed operative discoveries (e.g., dense adhesions) and were not the result of injury. CONCLUSIONS: There is wide variability in the amount and type of data reported within any single study, and patient populations may not be comparable across studies. Except for a higher common bile duct injury rate, laparoscopic cholecystectomy appears to be at least as safe a procedure as that of open cholecystectomy.

Cholecystectomy, Laparoscopic↗