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Biomedical subjects

R Norris

Publications and source records attributed to R Norris.

At least 19 recordsLinked to original sources
PubMed2005

Redefining the coronary care unit: an observational study of patients admitted to hospital in England and Wales in 2003.

BACKGROUND: Coronary care units were developed in the 1960s as specially equipped and staffed areas where patients with acute myocardial infarction could be monitored and offered rapid resuscitation from life-threatening arrhythmias. Awareness of the morbidity and mortality of the wider spectrum of acute coronary ischaemia was unrecognized at that time. AIM: To examine the relative frequencies with which thrombolytic treatment and resuscitation from cardiac arrest are provided for patients with myocardial infarction in cardiac care units (CCUs), emergency departments (EDs) and other medical wards. DESIGN: Observational study. METHODS: We analysed records from the National Audit of Myocardial Infarction Project (MINAP) for 61 688 patients admitted to 230 acute hospitals in England and Wales during 2003, and who received a final diagnosis of myocardial infarction, for locations of initiation of thrombolytic therapy and of first cardiac arrest within hospital. RESULTS: Overall, 84% of 27 881 patients with ST-segment-elevation infarction, but only 42% of 30 382 patients with non-ST-elevation infarction, were admitted to a CCU. Of those receiving thrombolytic treatment for ST-elevation infarction, 68.3% of 21 595 did so in the ED. Within the first 4 h after arrival, the majority of episodes of cardiac arrest occurred in the ED: 709 (57%) vs. 488 (39%) in CCU, and 49 (4%) in medical wards. DISCUSSION: The traditional role of the CCU in providing early resuscitation and thrombolytic treatment for patients with ST elevation infarction has largely been devolved to the ED. The role of the CCU should be re-evaluated, and the service re-designed to provide specialist care for all presentations of acute coronary syndrome.

Aged↗
PubMed2002

Acidophiles of saline water at thermal vents of Vulcano, Italy.

DNA was extracted from samples taken from close to acidic hydrothermal vents on shore of the Aeolian Island of Vulcano (Italy). RNA gene sequences were amplified by PCR, cloned, and sequenced. A sequence with an origin in samples at 35 degrees and 45 degrees C corresponded to that of a novel Acidithiobacillus species that was isolated from water close to the vents. Novel, iron-oxidizing mesophilic acidophiles were isolated through enrichment cultures with ferrous iron but were not represented in the clone banks of environmental rDNA. These acidophiles were related to Thiobacillus prosperus, which was isolated previously from Vulcano. The archaeal sequences that comprised a clone bank representing a high-temperature sample (75 degrees C) corresponded to those of Acidianus brierleyi and of thermophiles previously isolated from Vulcano, Thermoplasma volcanium and Acidianus infernus.

Bacteria↗
PubMed2000

Survival in epithelial ovarian cancer patients with prior breast cancer.

Ovarian cancer patients who carry germ-line BRCA1 mutations may have improved survival compared with ovarian cancer patients without these mutations. To evaluate this hypothesis, the authors compared survival in ovarian cancer patients who had a history of prior breast cancer with that of patients without such a history. Specifically, they used data from the population-based US Surveillance, Epidemiology, and End Results (SEER) Program to assess time to death from ovarian cancer among ovarian cancer patients with and without a prior breast cancer. All 25,637 White women diagnosed with invasive epithelial ovarian cancer in SEER registries between 1973 and 1995 were included. Of these, 824 women had had a prior breast cancer diagnosis. The ovarian cancer death rate among women with prior breast cancer was significantly lower than that of women with ovarian cancer only, adjusted for age and stage at ovarian cancer diagnosis. The survival advantage was most pronounced among older women and among those whose ovarian cancers were more advanced at the time of diagnosis. These results lend indirect support to prior findings of improved ovarian cancer survival in BRCA1 mutation carriers.

Adult↗
PubMed2000

Discovery of Circularly Polarized Radio Emission from SS 433.

We report the discovery of circularly polarized radio emission from the radio-jet X-ray binary SS 433 with the Australia Telescope Compact Array. The flux density spectrum of the circular polarization, clearly detected at four frequencies between 1 and 9 GHz, is of the form V~nu-0.9+/-0.1. Multiple components in the source and a lack of very high spatial resolution do not allow a unique determination of the origin of the circular polarization or of the spectrum of fractional polarization. However, we argue that the emission is likely to arise in the inner regions of the binary, possibly via propagation-induced conversion of linear to circular polarization, and the fractional circular polarization of these regions may be as high as 10%. Observations such as these have the potential to help us investigate the composition, whether pairs or baryonic, of the ejecta from X-ray binaries.

Journal Article↗
PubMed2000

Degradation of the cyanobacterial toxin cylindrospermopsin, from Cylindrospermopsis raciborskii, by chlorination.

Cylindrospermopsin, a potent cyanobacterial toxin produced by Cylindrospermopsis raciborskii and other cyanobacteria, is regularly found in water supplies of Queensland, Australia. This study focussed on the effectiveness of chlorination as a water treatment procedure for cylindrospermopsin degradation. The results demonstrate that relatively low chlorine doses (<1 mg l(-1)) are sufficient for degradation of cylindrospermopsin, when the dissolved organic carbon content is low. However, if organic matter other than cylindrospermopsin is present in the solution, the effectiveness of chlorine for cylindrospermopsin degradation is reduced as other organic matter present consumes chlorine. Under the experimental conditions using samples with a solution pH of 6-9, a residual chlorine concentration of 0.5 mg l(-1)99% of cylindrospermopsin. Toxin degradation via chlorination occurs within the first minute and no difference was observable between degradation in an open system and in a closed system. With a decrease of the pH from 6 to 4 a reduction in the efficiency of chlorine for degradation of cylindrospermopsin was observable, a possible indication that cylindrospermopsin is more stable to chlorine degradation at lower pH. However, in normal water treatment this is not relevant since the pH is consistently higher than 6.

Alkaloids↗
PubMed1999

Molecular evidence of cryptic speciation in planktonic foraminifers and their relation to oceanic provinces.

The fossil record of planktonic foraminifers is a key source of data on the biodiversity and evolution of marine plankton. One of the most distinctive foraminiferal taxa, Orbulina universa, widely used as a stratigraphic and paleoclimatic index, has always been regarded as a single species. Here we present a phylogenetic analysis of Orbulina small subunit rDNA sequences from 25 pelagic stations covering 100 degrees latitude in the Atlantic Ocean. The genetic data reveal the presence of three cryptic species, whose distribution is clearly correlated to hydrographic provinces, and particularly to sea-surface total chlorophyll a concentration. Our results, together with previous studies, suggest that a considerable part of the diversity among planktonic foraminifers has been overlooked in morphological taxonomies. Our data also support the idea that planktonic foraminifers, even if adapted to particular hydrographic conditions, are high-dispersal organisms whose speciation may be similar to that of other high-dispersal taxa in which reproductive mechanisms and behavior, rather than just geographic barriers to dispersal, play key roles in species formation and maintenance.

Animals↗
PubMed1999

Mechanical properties of several nickel-titanium alloy wires in three-point bending tests.

The purpose of this study was to clarify the mechanical properties of 42 brands of nickel-titanium alloy orthodontic wires from 9 manufacturers by conducting three-point bending tests under uniform testing conditions. Manufacturers included A-Company, Hoya Medical, Lancer, Ormco, Rocky Mountain, Sankin, Tomy (GAC), TP, and 3M/Unitek. Cobalt-chrome, and titanium-molybdenum alloy wires were also tested as a reference for comparison of force levels. All reported data were recorded during the unloading process to simulate the force that a wire exerts on a tooth as it is moved into the dental arch from a position of malocclusion. The following results were obtained for the nickel-titanium wires tested. (1) Among the 0.016 inch round wires tested under a maximum deflection of 1.5 mm, the difference between the smallest (Copper nickel-titanium 35) and the largest (Aline) load values was 136 g. For the 0.016 x 0.022 inch rectangular wires tested, the difference between the smallest (Copper nickel-titanium 40) and the largest (Aline) load values was 337 g. (2) The change in load between 1.5 and 0.5 mm of deflection was examined to clarify the superelastic properties of the wires tested. For the 0.016 inch wires, 17 wire brands produced a load difference of less than 100 g, and two brands produced a difference of at least 100 g (Aline and Titanal = 100 g). For the 0.016 x 0.022 inch wires, 15 brands produced a load difference of less than 100 g, and eight brands produced a difference of over 100 g. The smallest and largest load differences were 3 g (Copper nickel-titanium 35) and 200 g (Aline). (3) The majority of the samples with a smaller load difference between deflections of 1.5 mm and 0.5 mm in the unloading process were found among super-elastic wires, while samples with a larger load difference were predominantly found among work-hardened wires. Compared with cobalt-chrome and TMA wires, nickel-titanium alloy wires exert significantly less force. However, the amount of force varies greatly from brand to brand. Consequently, when using nickel-titanium alloy wires, brands must be selected carefully by taking into consideration the severity of the malocclusion and the stage of orthodontic treatment in each case. It is the intent of this study to offer clinicians an unbiased guide for the selection of appropriate nickel-titanium alloy wires.

Dental Alloys↗
PubMed1999

High-resolution HLA-A*0201 subtyping using directed heteroduplex analysis.

HLA-A02* has become an important target for cytotoxic T lymphocyte-based immunotherapy reflecting the high prevalence of this allele in patient populations. There are at least 26 different A*02 alleles, and their subtype specificity has significant functional implications for T-cell-mediated recognition of immunologic targets. We have developed a novel method for HLA-A*02 allelic screening using directed heteroduplex analysis (DHDA). DNA samples from Epstein-Barr virus (EBV)-transformed B lymphoblastoid cell lines (EBV-B) representing 10 different HLA-A*02 alleles (0201, 0202, 0204, 0205, 0206, 0208, 0210, 0211, 0216, 0217) were prepared. In addition, DNA was prepared from 81 individuals representing a wide variety of A*02 subtypes previously determined by sequence specific primer (SSP) polymerase chain reaction (PCR) including individuals heterozygous for two A*02 specificities. Probes and samples were generated by PCR amplification using HLA-A*02 specific primers encompassing exons 2 and 3, where most of the functionally significant allelic polymorphism is clustered. DHDA was performed by generating heteroduplex molecules composed of a fluorescein-labeled allelic probe sequence and an unlabeled allelic PCR product. Gel retardation was consistent for allele-probe combinations. We were able to identify several A*02 alleles prepared from EBV-B cell lines that, when used as probes, had very impressive specificity and sensitivity. Combinations of two probes were identified (0205 + 0211 and 0208 + 0211) that allowed differentiation of A*0201 alleles from all other A*02 alleles tested. All samples typed by probe combinations had DHDA typing and SSP typing confirmed by DNA sequencing. This study expands the molecular typing repertoire available to the modern HLA laboratory, and shows that DHDA has significant promise as a reliable screening method for HLA A*02 subtyping.

B-Lymphocytes↗
PubMed1998

Pulmonary infiltrates in the surgical ICU: prospective assessment of predictors of etiology and mortality.

A prospective cohort study of 129 consecutive patients developing pulmonary infiltrates in the surgical ICU was conducted to determine the predictors and outcome of pulmonary infiltrates. Most common etiologies of pulmonary infiltrates were pneumonia (30%), pulmonary edema (29%), acute lung injury (15%), and atelectasis (13%). Enteral nutrition was associated with a significantly lower incidence of acute lung injury as compared with pneumonia (22% vs 58%, p = 0.012). Patients with liver disease were significantly more likely to have pulmonary infiltrates due to acute lung injury as compared with other etiologies (p = 0.02). Clinical pulmonary infection score (Pugin score) > 6 virtually excluded acute lung injury, pulmonary edema, or atelectasis as etiologies of pulmonary infiltrates. Nosocomial Haemophilus/pneumococcal pneumonia occurred significantly earlier in the ICU as compared with Gram-negative (p = 0.05) or methicillin-resistant Staphylococcus aureus pneumonia (p = 0.01). Pneumonia in trauma patients was significantly more likely to be due to Haemophilus/pneumococcus as compared with all other ICU patients (54% vs 0%, p = 0.0004). These data have implications for treatment of patients with nosocomial pneumonia in the ICU.

APACHE↗
PubMed1997

How mental health and developmental disabilities staff prioritize training and development needs.

This paper contrasts a staff training needs assessment distributed to three groups: staff serving persons with mental health needs in the community, staff serving persons with mental health needs in state hospitals, and staff serving persons with developmental disabilities in the community. Analyses revealed that all three groups rated team-related training as the area in greatest need of development. Further analyses suggested that community staff serving persons with developmental disabilities reported significantly less need for training on direct client care compared to community and inpatient staff who serve persons with mental health needs. The community staff serving persons with mental health needs did not differ significantly from the inpatient staff on any of the surveyed training areas. Results suggest that future development efforts should begin with team building skills.

Adult↗
PubMed1997

Adhesion, internalization and metabolism of calcium oxalate monohydrate crystals by renal epithelial cells.

The interaction between crystals that nucleate in the nephron lumen and tubular cells could be an important determinant of renal calcification. Kidney epithelial cells in monolayer culture (BSC-1 line), used to model the tubule, rapidly bound and internalized crystals of calcium oxalate monohydrate (COM), the most common constituent of renal stones. Transmission and scanning electron microscopy, enzyme histochemistry, and kinetic analysis of [14C]-labeled crystals were used to study the interaction between renal cells and COM crystals. Electron microscopy revealed that adherent crystals on the apical cell surface can serve as sites for aggregation of additional crystals. Enhanced binding of exogenous crystals to plasma membrane domains overlying internalized crystals was observed for at least 24 hours after the initial cell-crystal interaction. Following internalization, crystals appeared to dissolve within lysosomal inclusion bodies during the ensuing five to seven weeks. Over this time, many cells still containing crystals clustered together in the monolayer. These observations suggest that adhesion and internalization can promote crystal retention in the nephron, whereas intracellular dissolution of crystals may serve as an important, hitherto unrecognized defense against pathologic renal calcification.

Animals↗
PubMed1997

Adhesion of hydroxyapatite crystals to anionic sites on the surface of renal epithelial cells.

Adhesion of microcrystals that nucleate in tubular fluid to the apical surface of renal tubular cells could be a critical step in the formation of kidney stones, 20% of which contain hydroxyapatite (HA). HA crystals bound rapidly to monolayer cultures of monkey kidney epithelial cells (BSC-1 line), used to model the surface of the nephron, in a concentration-dependent manner. Adhesion was blocked by diverse polyanions including heparin, pentosan polysulfate, polyaspartate, and polyglutamate, as well as many found in tubular fluid such as chondroitin sulfates A and B, heparan sulfate, citrate, nephrocalcin, and osteopontin. The polycations cetylpyridinium chloride and cationized ferritin, as well as the cationic dyes alcian blue, polyethylenimine, and brilliant blue R, also inhibited adhesion of HA crystals, as did specific lectins including Triticum vulgaris (wheat germ agglutinin). Anions that inhibited adhesion of crystals appeared to act on the crystal surface, whereas cations and lectins exerted their effect on the cell. Treatment of cells with neuraminidase inhibited binding of crystals, suggesting that anionic cell surface sialic acid residues function as HA crystal receptor sites that can be blocked by specific cations or lectins. Adherence of HA crystals to cells of another renal line (MDCK) and, to 3T3 fibroblasts was also inhibited by heparin, polyaspartate, alcian blue, and T vulgaris lectin, suggesting that these crystals bind to analogous molecules on the surface of different types of cells. These results suggests that the structure, quantity, and/or function of soluble anions in tubular fluid, as well as those anchored to the cell surface, could be critical determinants of HA crystal retention in the nephron and the subsequent formation of a renal stone.

Animals↗
PubMed1994

Effect of coronary artery bypass graft surgery on survival: overview of 10-year results from randomised trials by the Coronary Artery Bypass Graft Surgery Trialists Collaboration.

We carried out a systematic overview using individual patient data from the seven randomised trials that have compared a strategy of initial coronary artery bypass graft (CABG) surgery with one of initial medical therapy to assess the effects on mortality in patients with stable coronary heart disease (stable angina not severe enough to necessitate surgery on grounds of symptoms alone, or myocardial infarction). 1324 patients were assigned CABG surgery and 1325 medical management between 1972 and 1984. The proportion of patients in the medical treatment group who had undergone CABG surgery was 25% at 5 years, 33% at 7 years, and 41% at 10 years: 93.7% of patients assigned to the surgery group underwent CABG surgery. The CABG group had significantly lower mortality than the medical treatment group at 5 years (10.2 vs 15.8%; odds ratio 0.61 [95% CI 0.48-0.77], p = 0.0001), 7 years (15.8 vs 21.7%; 0.68 [0.56-0.83], p < 0.001), and 10 years (26.4 vs 30.5%; 0.83 [0.70-0.98]; p = 0.03). The risk reduction was greater in patients with left main artery disease than in those with disease in three vessels or one or two vessels (odds ratios at 5 years 0.32, 0.58, and 0.77, respectively). Although relative risk reductions in subgroups defined by other baseline characteristics were similar, the absolute benefits of CABG surgery were most pronounced in patients in the highest risk categories. This effect was most evident when several prognostically important clinical and angiographic risk factors were integrated to stratify patients by risk levels and the extension of survival at 10 years was examined (change in survival -1.1 [SE 3.1] months in low-risk group, 5.0 [4.2] months in moderate-risk group, and 8.8 [5.4] months in high-risk group; p for trend < 0.003). A strategy of initial CABG surgery is associated with lower mortality than one of medical management with delayed surgery if necessary, especially in high-risk and medium-risk patients with stable coronary heart disease. In low-risk patients, the limited data show a non-significant trend towards greater mortality with CABG.

Adult↗
PubMed1992

Measurement of dothiepin and its major metabolites in plasma by high-performance liquid chromatography.

This paper describes a reversed-phase high-performance liquid chromatographic method which will simultaneously measure dothiepin and its three major metabolites (northiaden, northiaden-S-oxide and dothiepin-S-oxide) in plasma using trimipramine as internal standard. Sample preparation involved a basic extraction using diethyl ether followed by an acid back-extraction. The method we report is linear over the range 50-1000 ng/ml (r = 0.999), for all analytes. Total imprecision is less than 11% (coefficient of variation) and accuracy is greater than 94% (n = 20). Recovery of analytes varied considerably from 51.7% for northiaden-S-oxide to 90.2% for dothiepin-S-oxide.

Chromatography, High Pressure Liquid↗
PubMed1992

The effects of physical activity and exercise training on psychological stress and well-being in an adolescent population.

To determine whether participating in physical activity affects psychological well-being in an adolescent population, 147 adolescents completed self-reports of exercise and psychological stress and well-being. Analysis revealed that those who reported greater physical activity also reported less stress and lower levels of depression. Adolescents who experienced a higher incidence of life events also demonstrated a strong association between stress and anxiety/depression/hostility. To investigate the effects of exercise training on psychological well-being, adolescents were assigned to either high or moderate intensity aerobic training, flexibility training or a control group. The training groups met twice per week for 25-30 min. Aerobic fitness levels, heart rate, blood pressure and self-report of stress and well-being were measured prior to and following 10 weeks of training. Post-training fitness measures confirmed the effectiveness of the high intensity aerobic exercise and between groups differences for physiological and some psychological measures were found. Subjects undergoing high intensity exercise reported significantly less stress than subjects in the remaining three groups. The relationship between stress and anxiety/depression/hostility for the high intensity group was considerably weakened at the end of the training period. For the remaining subjects, however, this relationship was, if anything, strengthened. This experiment provides evidence to suggest that in an adolescent population, high intensity aerobic exercise has positive effects on well-being.

Adaptation, Psychological↗
PubMed1992

Silent ischemia in rehabilitation patients: limited clinical utility of electrocardiographic monitoring.

In a prospective blinded trial, 24-hour continuous electrocardiographic monitoring for silent ischemia was used to try to identify rehabilitation patients at risk for cardiac complications. Five of 42 patients had episodes of silent ischemia, none of which occurred during physical therapy sessions. One of these patients had syncope while wearing the Holter; none of the other four patients had significant cardiac complications during their rehabilitation, and all were discharged home. None of the patients without ischemia on the monitor had complications, but two patients of 14 whose ECGs precluded monitoring for ischemia had complications. In addition, six patients had episodes of nonsustained asymptomatic ventricular tachycardia, 12 had episodes of supraventricular tachycardia, and four had significant ventricular ectopy, all without clinical significance. Despite the apparent high sensitivity and specificity of the technique, the positive predictive value of monitoring eligible patients for silent ischemia was 20%. We conclude that ambulatory electrocardiographic monitoring for silent ischemia or ectopy has limited clinical utility in the rehabilitation population.

Aged↗