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Biomedical subjects

R Evans

Publications and source records attributed to R Evans.

At least 109 records · Page 6Linked to original sources
PubMed2000

In vitro effects of low-level laser irradiation at 660 nm on peripheral blood lymphocytes.

BACKGROUND AND OBJECTIVE: The effects of low-level laser light irradiation are still highly contested, and the mechanisms of its action still unclear. This study was conducted to test the effects of low-level laser irradiation at 660 nm on human lymphocytes and to investigate the possible mechanisms by which these effects are produced. STUDY DESIGN/MATERIALS AND METHODS: Whole blood obtained by phlebotomy was irradiated at 660 nm by using energy fluences between 0 and 5.0 J/cm(2). The lymphocytes were isolated after irradiation of the whole blood. For the control experiment, the lymphocytes were first isolated and then irradiated at the same wavelength and energy fluence for comparison. The proliferation of lymphocytes and the formation of free radicals and lipid peroxides were monitored. Hemoglobin was also irradiated in a cell-free environment to test for the production of lipid peroxides. RESULTS: Lymphocyte proliferation was significantly higher (P<0.05) as expressed by a Stimulation Index in samples irradiated in the presence of whole blood compared with lymphocytes irradiated after isolation from whole blood. Free radical and lipid peroxide production also increased significantly when samples were irradiated in the presence of red blood cells. CONCLUSION: The present study supports the hypothesis that one mechanism for the photobiostimulation effect after irradiation at 660 nm is the reaction of light with hemoglobin, resulting in oxygen radical production.

Blood↗
PubMed2000

Evidence-based diagnosis of toxoplasma infection.

The aim of this study was to compare the performance of one in-house and four commercially available toxoplasma assays with the Sabin-Feldman dye test. One hundred fifty-seven routine sera and 20 potentially cross-reactive sera were tested blindly using four commercial assays: Abbott AxSym IgG (Abbott Laboratories, UK), Captia Select Toxo-G (Trinity Biotech, UK), Toxreagent 'Eiken' (Eiken Chemical, Japan) and Toxolatex Fumouze (Fumouze Laboratoires, France); an in-house IgG and IgM enzyme immunoassay (EIA); and the gold standard Sabin-Feldman dye test. The sensitivity, specificity and the values using the formulae for numbers needed to diagnose (NND) and the cost per positive diagnosis (CPPD) were calculated for each assay. These formulae use the sensitivity and specificity of the assay to allow for evidence-based comparisons between assays. The NND values for the in-house IgG EIA, AxSym, Eiken and Fumouze latex kits were similar (1.21-1.24), whereas the Captia yielded the poorest value (1.33). The in-house EIA IgG had the lowest CPPD value (pound sterling 0.57/$0.91), and the Fumouze and Eiken latex kits had the lowest CPPD values for commercial assays (pound sterling 1.42/$2.27 and pound sterling 1.81/$2.90, respectively). Both assays were simple and straightforward to use. Specialist laboratories should opt to use in-house assays, as they were most cost-effective. Although nonspecialist laboratories could use commercial assays, specimens from immunocompromised patients and patients with ocular disease should be forwarded to specialist laboratories without prior testing.

Animals↗
PubMed2000

Outcomes of a population-based asthma management program: quality of life, absenteeism, and utilization.

BACKGROUND: Despite the availability of the National Asthma Education Program (NAEP) guidelines since 1991, asthma remains inadequately managed. To improve quality of life, functional status, and self-management behavior of asthma patients, a large health maintenance organization (HMO) in California implemented an asthma management program in 1996. OBJECTIVE: To evaluate the effectiveness of an asthma management program in an HMO setting. DESIGN AND SETTING: Prospective study. Survey data from members who participated in the intervention program and data from members who received usual care were analyzed using propensity score technique. RESULTS: A total of 1,043 asthma patients who responded both baseline and follow-up survey were included in the analysis. From baseline to followup, participants in the in-home intervention program reported significant improvement in functional status (improvements range from 0.2 to 7.2), daily use of steroid inhaler (+4.1%), daily peak flow meter use (+6.4%), self-reported knowledge of what to do for an asthma attack (+12.4%), and feeling that their asthma was under control (+10.8%). Absenteeism (-11.8%) and hospitalization due to asthma (-3.5%) were significantly reduced from baseline to follow-up. Participants did not report significant changes in overuse of beta2-agonists and emergency room visits due to asthma. In comparison with the asthmatic patients who received usual care (non-participants), participants had significantly greater improvement on daily use of steroid inhaler (+4.0% versus -6.0%), daily use of home peak flow meter (+6.4% versus 1.9%) and self-reported knowledge on what to do for an asthma attack (+12.4% versus +5.4%). CONCLUSION: These findings suggest that population-based programs can improve functional status, increase self-monitoring and knowledge about asthma, and decrease absenteeism and hospitalization for asthma by directly providing asthmatic patients with educational materials and self-monitoring tools. Such "direct-to-consumer" outreach programs may help bridge the gap between NAEPs 1991 practice guidelines and the reality of current asthma management.

Absenteeism↗
PubMed2000

LMNA, encoding lamin A/C, is mutated in partial lipodystrophy.

The lipodystrophies are a group of disorders characterized by the absence or reduction of subcutaneous adipose tissue. Partial lipodystrophy (PLD; MIM 151660) is an inherited condition in which a regional (trunk and limbs) loss of fat occurs during the peri-pubertal phase. Additionally, variable degrees of resistance to insulin action, together with a hyperlipidaemic state, may occur and simulate the metabolic features commonly associated with predisposition to atherosclerotic disease. The PLD locus has been mapped to chromosome 1q with no evidence of genetic heterogeneity. We, and others, have refined the location to a 5.3-cM interval between markers D1S305 and D1S1600 (refs 5, 6). Through a positional cloning approach we have identified five different missense mutations in LMNA among ten kindreds and three individuals with PLD. The protein product of LMNA is lamin A/C, which is a component of the nuclear envelope. Heterozygous mutations in LMNA have recently been identified in kindreds with the variant form of muscular dystrophy (MD) known as autosomal dominant Emery-Dreifuss MD (EDMD-AD; ref. 7) and dilated cardiomyopathy and conduction-system disease (CMD1A). As LMNA is ubiquitously expressed, the finding of site-specific amino acid substitutions in PLD, EDMD-AD and CMD1A reveals distinct functional domains of the lamin A/C protein required for the maintenance and integrity of different cell types.

Amino Acid Sequence↗
PubMed2000

Retinitis and dementia in a pregnant girl: an unusual case.

A 14-year-old pregnant Caucasian girl presented with a 1-week history of dementia. She had presented 1 year prior with acute unilateral visual impairment and was noted to have macular degeneration of presumed infective aetiology. This evolved to a pigmentary macular lesion. During the course of the current presentation she developed myoclonic jerks. An electroencephalogram revealed periodic spike and slow wave complexes at 1-2 second intervals. Blood and cerebrospinal fluid examination showed raised anti-measles IgG antibody titres. Intrathecal synthesis of anti-measles virus antibody was demonstrated unequivocally and a diagnosis of subacute sclerosing panencephalitis was made. A healthy male infant was delivered by elective caesarean section at 33 weeks' gestation. She continued to deteriorate clinically despite treatment with intraventricular alpha-interferon. She had not had primary immunization against measles.

Adolescent↗
PubMed2000

Relative importance of flow versus pressure in splanchnic perfusion during cardiopulmonary bypass in rabbits.

BACKGROUND: Decreased gastrointestinal perfusion has been reported during cardiopulmonary bypass (CPB). Conflicting results have been published concerning thresholds of pressure and flow to avoid splanchnic ischemia during CPB. This study compared splanchnic perfusion during independent and randomized variations of CPB pump flow or arterial pressure. METHODS: Ten rabbits were studied during mild hypothermic (36 degrees C) nonpulsatile CPB using neonatal oxygenators. Simultaneous measurements of tissue blood flow in four different splanchnic areas (gastric, jejunum, ileum, and liver) were performed by laser Doppler flowmetry (LDF) before CPB (T0) and during a 4-step factorial experimental block design. Pressure and flow were alternatively high or low in random order. RESULTS: Laser Doppler flowmetry was significantly lower than pre-CPB value but was better preserved (analysis of covariance) in all organs, except liver, when CPB flow was high, whatever the pressure. Splanchnic LDF values in the low- versus high-flow groups expressed as perfusion unit were (mean +/- SD): stomach, 94+/-66 versus 137+/-75; jejunum, 118+/-78 versus 172+/-75; ileum, 95+/-72 versus 146+/-83; and liver, 79+/-72 versus 108+/-118. No significant difference of LDF was observed between the high- and low-pressure groups, whatever the flow, except for liver: stomach, 115+/-64 versus 117+/-83; jejunum, 141+/-80 versus 148+/-83; ileum, 127+/-87 versus 114+/-76; liver, 114+/-88 versus 73+/-70. CONCLUSION: Prevention of splanchnic ischemia during CPB should focus on preservation of high CPB blood flow rather than on high pressure.

Animals↗
PubMed2000

Usefulness of procalcitonin for diagnosis of infection in cardiac surgical patients.

OBJECTIVE: To determine the value of procalcitonin (PCT) as a marker of postoperative infection after cardiac surgery. DESIGN: A prospective single institution three phase study. SETTING: University cardiac surgical intensive care unit (31 beds). PATIENTS: Phase 1: To determine the normal perioperative kinetics of PCT, 20 consecutive patients undergoing elective cardiac surgery with cardiopulmonary bypass were included. Phase 2: To determine whether PCT may be useful for diagnosis of postoperative infection, 97 consecutive patients with suspected infection were included. Phase 3: To determine the ability of PCT to differentiate patients with septic shock from those with cardiogenic shock, 26 patients with postoperative circulatory failure were compared. MEASUREMENTS AND MAIN RESULTS: Phase 1: Serum samples were drawn for PCT determination after induction of anesthesia (baseline), at the end of surgery, and daily until postoperative day (POD) 8. Baseline serum PCT concentration was 0.17 +/- 0.08 ng/mL (mean +/- SD). Serum PCT increased after cardiac surgery with a peak on POD 1 (1.08 +/- 1.36). Serum PCT returned to normal range on POD 3 and remained stable thereafter. Phase 2: In patients with suspected infection, serum PCT was measured at the same time of C-reactive protein (CRP) and bacteriologic samples. Among the 97 included patients, 54 were infected with pneumonia (n = 17), bacteremia (n = 16), mediastinitis (n = 9), or septic shock (n = 12). In the 43 remaining patients, infection was excluded by microbiological examinations. In noninfected patients, serum PCT concentration was 0.41 +/- 0.36 ng/mL (range, 0.08-1.67 ng/mL). Serum PCT concentration was markedly higher in patients with septic shock (96.98 +/- 119.61 ng/mL). Moderate increase in serum PCT concentration occurred during pneumonia (4.85 +/-3.31 ng/mL) and bacteremia (3.57 +/- 2.98 ng/mL). Serum PCT concentration remained low during mediastinitis (0.80 +/- 0.58 ng/mL). Five patients with mediastinitis, two patients with bacteremia, and one patient with pneumonia had serum PCT concentrations of <1 ng/mL. These eight patients were administered antibiotics previously and serum PCT was measured during a therapeutic antibiotic window. For prediction of infection by PCT, the best cutoff value was 1 ng/mL, with sensitivity 85%, specificity 95%, positive predictive value 96%, and negative predictive value 84%. Serum CRP was high in all patients without intergroup difference. For prediction of infection by CRP, a value of 50 mg/L was sensitive (84%) but poorly specific (40%). Comparing the area under the receiver operating characteristic curves, PCT was better than CRP for diagnosis of postoperative sepsis (0.82 for PCT vs. 0.68 for CRP). Phase 3: Serum PCT concentration was significantly higher in patients with septic shock than in those with cardiogenic shock (96.98 +/- 119.61 ng/mL vs. 11.30 +/- 12.3 ng/mL). For discrimination between septic and cardiogenic shock, the best cutoff value was 10 ng/mL, with sensitivity of 100% and specificity of 62%. CONCLUSION: Cardiac surgery with cardiopulmonary bypass influences serum PCT concentration with a peak on POD 1. In the presence of fever, PCT is a reliable marker for diagnosis of infection after cardiac surgery, except in patients who previously received antibiotics. PCT was more relevant than CRP for diagnosis of postoperative infection. During a postoperative circulatory failure, a serum PCT concentration >10 ng/mL is highly indicative of a septic shock.

Adult↗
PubMed2000

Depletion potential in hard-sphere mixtures: theory and applications

We present a versatile density functional approach (DFT) for calculating the depletion potential in general fluid mixtures. For the standard situation of a single big particle immersed in a sea of small particles near a fixed object, the system is regarded as an inhomogeneous binary mixture of big and small particles in the external field of the fixed object, and the limit of vanishing density of the big species, rho(b)-->0, is taken explicitly. In this limit our approach requires only the equilibrium density profile of a one-component fluid of small particles in the field of the fixed object, and a knowledge of the density independent weight functions which characterize the mixture functional. Thus, for a big particle near a planar wall or a cylinder or another fixed big particle, the relevant density profiles are functions of a single variable, which avoids the numerical complications inherent in brute force DFT. We implement our approach for additive hard-sphere mixtures, comparing our results with computer simulations for the depletion potential of a big sphere of radius R(b) in a sea of small spheres of radius R(s) near (i) a planar hard wall, and (ii) another big sphere. In both cases our results are accurate for size ratios s=R(s)/R(b) as small as 0.1, and for packing fractions of the small spheres eta(s) as large as 0.3; these are the most extreme situations for which reliable simulation data are currently available. Our approach satisfies several consistency requirements, and the resulting depletion potentials incorporate the correct damped oscillatory decay at large separations of the big particles or of the big particle and the wall. By investigating the depletion potential for high size asymmetries we assess the regime of validity of the well-known Derjaguin approximation for hard-sphere mixtures and argue that this fails, even for very small size ratios s, for all but the smallest values of eta(s) where the depletion potential reduces to the Asakura-Oosawa potential. We provide an accurate parametrization of the depletion potential in hard-sphere fluids, which should be useful for effective Hamiltonian studies of phase behavior and colloid structure. Our results for the depletion potential in a hard-sphere system, with a size ratio s=0.0755 chosen to mimic a recent experiment on a colloid-colloid mixture, are compared with the experimental data. Although there is good overall agreement, in particular for the dependence of the oscillations on eta(s), there are some significant differences at high values of eta(s).

Journal Article↗
PubMed2000

Toxoplasma dye test using cell culture derived tachyzoites.

AIMS: To assess the diagnostic usefulness of Toxoplasma gondii tachyzoites produced by serial passage in HeLa cell culture. METHODS: Tachyzoites derived from serial passage in cell culture were used in the dye test. Human sera were also examined to determine their suitability for use as accessory factor. Using the optimum conditions, the dye test using cell culture derived tachyzoites was compared with the current method of production (animal culture) on 105 randomly selected sera. Start up and maintenance costs of each system were compared. RESULTS: Tachyzoites in most cell culture harvests (84%) from both early and later passes were useable. Tachyzoite yield and viability were maintained during serial passage in cell culture. Sodium citrate was used to modify accessory factor and improve its suitability. The performance of the accessory factor was improved by the addition of 1% and 3% sodium citrate for the current and cell culture systems, respectively. Under optimum conditions, dye test titres using cell culture and current systems were compared on 105 randomly selected sera. The results from 92 of 105 (87.6%) patients agreed or were within one dilution, but all discrepancies were resolved on re-testing. Start up costs for the current system would be 2.5 times and overall maintenance three times more expensive than cell culture. CONCLUSIONS: Tachyzoites derived from cell culture can be used routinely in the dye test. Production in cell culture is more cost effective than animal culture. It is possible for general hospitals to perform the dye test, thus obtaining faster and more specific results.

Animals↗
PubMed2000

Transfusion-related acute lung injury associated with interdonor incompatibility for the neutrophil-specific antigen HNA-1a.

BACKGROUND AND OBJECTIVES: A patient transfused with two pooled platelet concentrates became breathless. Bilateral infiltrates were seen on chest X-ray. A diagnosis of transfusion-related acute lung injury (TRALI) was made. The patient received 100% oxygen and recovered after 5 days. MATERIALS AND METHODS: Antibody screening, cross-matching for granulocyte and lymphocyte antibodies and typing for granulocyte antigens was undertaken. RESULTS: The patient typed as HNA-1b/HNA-1b. Granulocyte and lymphocyte antibodies were not detected in the patient's serum or in any of the donor sera by cross-match. In antibody screening against typed panel granulocytes, complement-fixing anti-HNA-1a IgM antibodies were detected in the serum of one female donor. Two of the other donors who contributed to the pooled platelet concentrate containing the HNA-1a IgM antibodies typed as HNA-1a/HNA-1b. CONCLUSION: Anti-HNA-1a IgM antibodies may have formed immune complexes with white cell fragments or soluble FcgammaRIII from HNA-1a+ donors in the pooled platelet concentrate and initiated TRALI.

Adult↗
PubMed2000

Antidotes--inappropriate timely availability.

The aim of this study was to determine the availability of antidotes to poisons in Wales and the South West of England. A stocklist of antidotes that are available to accident and emergency departments was requested and was compared with recommendations from the International Programme on Chemical Safety (IPCS). Chief pharmacists were invited to complete a short questionnaire regarding knowledge of existing guidelines. Thirty-four of 43 centres replied (response rate 77%). No department held all 36 antidotes (mean 13, range 7-33). All departments held antidotes that were frequently used. Ninety-one percent of departments held one cyanide antidote. Eighty-eight percent held one heavy metal chelating agent. The remaining antidotes were variably stocked. New agents such as 4-methylpyrazole, hydroxocobalamin and the heavy metal chelating agents DMSA and DMPS were infrequently held. Twenty of 34 chief pharmacists were unfamiliar with existing UK guidelines. A trend exists whereby larger departments stocked more antidotes. Some antidotes to poisons are not available in a timely fashion in Wales and the South West of England. There is a lack of awareness of existing guidelines. New recommendations relevant to clinical need and local practice should ideally be developed.

Antidotes↗
PubMed2000

A comparative analysis of sextant and an extended 11-core multisite directed biopsy strategy.

PURPOSE: The 3 tumor locations unsampled by conventional sextant biopsies that have been identified on composite 3-dimensional reconstruction of 180 radical prostatectomy specimens are the anterior transition zone, midline peripheral zone and inferior portions of the anterior horn in the peripheral zone. We evaluated an 11-core multisite directed biopsy scheme incorporating these alternate areas and conventional sextant biopsies in 362 patients from 2 institutions. MATERIALS AND METHODS: Patients without a prior diagnosis of cancer underwent ultrasound guided 11-core biopsies which included conventional sextant and 3 alternate sites. All specimens were separated for specific location identification. Biopsy was performed in 183 patients at MD Anderson Cancer Center (group 1) and in 179 at Toronto General Hospital (group 2). All group 2 and 54% of group 1 patients (98 of 183) had a prior biopsy negative for cancer. RESULTS: Median prostate specific antigen was higher in group 2 than in group 1 patients (11.5 versus 9.5 ng./ml., p = 0.016). Overall a 33% increase (36 of 110 patients) in cancer detection was observed when biopsy technique included the alternate areas (p = 0.0021). The anterior horn was the most frequently positive biopsy site followed by the transition zone and midline sites. The 11-core technique had significantly better cancer detection rates when digital rectal examination and transrectal ultrasound were normal, and in men with serum prostate specific antigen between 4.1 and 10 ng./ml. CONCLUSIONS: Biopsies of the alternate sites suggested by our simulation studies are feasible and reproducible. This new strategy significantly enhanced (p = 0.0075) prostate cancer detection compared to conventional sextant biopsies in men undergoing a repeat procedure.

Adult↗
PubMed2000

Spectroscopic determination of skin viability. A predictor of postmortem interval.

We have demonstrated that skin viability decreases at a measurable rate following death in an animal model. The decreased skin viability was measured by fluorescein diacetate and ethidium bromide using fluorescence emission spectroscopy. There is significant decrease of the fluorescence intensity of the fluorescein diacetate assay between the 1-4 h, the 6-24 h, and the >40 h time points postmortem. For times between 6-24 h and >40 h postmortem the ethidium bromide assay showed consistent and significant increases in signal. The fluorescence measurements in this study showed that under the experimental conditions the time of death could be determined for <4, 6-24, and >40 hapotmotrem. The application of these assays in the field will require further study of the environmental factors.

Animals↗