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Biomedical subjects

R Anderson

Publications and source records attributed to R Anderson.

At least 91 records · Page 5Linked to original sources
PubMed2001

Vitamin E attenuates the injurious effects of bioactive phospholipids on human ciliated epithelium in vitro.

Bioactive phospholipids (PL), particularly lysophosphatidylcholine (LPC), are being increasingly implicated in the pathogenesis of various acute and chronic inflammatory disorders, particularly those of the airways, while there is emerging evidence that vitamin E may function as a natural antagonist of these lipid mediators of inflammation. The aims of this study were to document the effects of vitamin E on the inhibition of ciliary beating and damage to structural integrity of human ciliated epithelium induced by the PL, platelet-activating factor (PAF), lyso-PAF and LPC in vitro in relation to the anti-oxidative and membrane-stabilizing properties of the vitamin. Ciliary beat frequency was measured by a phototransistor technique, and damage to structural integrity assessed by a visual-scoring index, while superoxide production by polymorphonuclear leukocytes and membrane-stabilizing potential were measured using lucigenin-enhanced chemiluminescence and haemolytic procedures, respectively. All three PL caused inhibition of ciliary beating and structural damage to human ciliated epithelium by membrane-directed cytotoxic mechanisms, which were potentiated by human polymorphonuclear leukocytes due to induction of oxidant-mediated injury. Both direct and phagocyte-inflicted epithelial injury was attenuated by vitamin E. In haemolytic and chemiluminescence assays, vitamin E neutralized both the membrane-destabilizing and pro-oxidative actions of all three PL, while spectrophotometric analysis of mixtures of vitamin E with PAF, lyso-PAF and LPC revealed alterations in peak intensity, as well as peak shifts, indicative of physicochemical interactions between the vitamin and the PL. Vitamin E status may be a determinant of susceptibility to phospholipid-mediated airway inflammation and damage.

Cells, Cultured↗
PubMed2001

Electrical impedance scanning: a new technique in the diagnosis of lymph nodes in which malignancy is suspected on ultrasound.

Differentiation between inflammatory and malignant lymph nodes by ultrasound is difficult. Electrical impedance scanning (EIS) is a new diagnostic tool, so far used primarily for the identification of malignant breast lesions. Cancer cells have altered dielectric properties compared with normal cells, thereby distorting the local electrical field. The induced changes in capacitance and conductivity are measurable using EIS. We evaluated EIS in demonstrating the cause of lymph node enlargement. 51 lymph nodes that were suspicious for malignancy on ultrasound (32 patients, mean age 32 years), with a mean size of 18 mm x 12 mm x 10 mm, were examined. The following lymph node locations were included in the study: cervical, inframandibular, axillary, paraaortic and inguinal. EIS results were compared with histopathological and follow-up findings. 30/34 malignant lymph nodes were correctly detected using EIS, while 14/17 inflammatory or benign lymph nodes were correctly identified as benign by EIS; thus, there were 4/51 false negative and 3/51 false positive cases. The sensitivity was 88.2% and the specificity was 82.4%. Corresponding negative and positive predictive values were 77.8% and 90.9%, respectively. Results from this initial study suggest the potential usefulness of EIS as an adjunctive imaging modality in the differentiation of lymphadenopathy that is equivocal on ultrasound. The best accuracy was obtained in the cervical, axillary and inguinal regions. Owing to technical restrictions of the present system, examination of inframandibular and paraaortic lymph nodes should be limited to special cases.

Adult↗
PubMed2001

Comparisons of two breast cancer risk estimates in women with a family history of breast cancer.

There is an increasing need for accurate prediction methods of assessing individual risk for breast cancer for both clinical and research purposes. The purpose of this study is to compare the Gail and Claus model risk estimates of breast cancer among women with a family history of breast cancer. This study presents risk estimates from two models of breast cancer risk in 491 women 18 to 74 years of age with a family history of breast cancer who were recruited to risk counseling clinical trials in Seattle, Washington between 1996 and 1997. These trials included women from the general population and additional samples of Ashkenazi Jewish, African-American, and lesbian women. We estimated and compared lifetime (to age 79) and 5-year risk for developing breast cancer using the National Surgical Adjuvant Breast and Bowel Project adaptation of the Gail model and the Claus model. About one-quarter of participants fell into the Gail "high" risk category (> or =1.7% risk of developing breast cancer in the next 5 years). The average lifetime risk was estimated at 13.2% by the Gail model and 11.2% by the Claus model. Estimates from the two models were moderately and positively correlated (r = 0.55) with the Gail model yielding a higher estimate than the Claus model for most participants. If women with a family history of breast cancer are being counseled regarding decisions on genetic testing, tamoxifen use, or other preventive measures, presenting both Claus and Gail estimates may be the best option.

Adolescent↗
PubMed2001

Prospective randomized controlled trial of extended-release oxybutynin chloride and tolterodine tartrate in the treatment of overactive bladder: results of the OBJECT Study.

OBJECTIVE: To compare the efficacy and tolerability of extended-release oxybutynin chloride and tolterodine tartrate at 12 weeks in participants with overactive bladder. SUBJECTS AND METHODS: The OBJECT (Overactive Bladder: Judging Effective Control and Treatment) study was a prospective, randomized, double-blind, parallel-group study conducted between March and October 2000 at 37 US study sites. Participants who had between 7 and 50 episodes of urge incontinence per week and 10 or more voids in 24 hours received extended-release oxybutynin, 10 mg/d, or tolterodine, 2 mg twice daily. The outcome measures were the number of episodes of urge incontinence, total incontinence, and micturition frequency at 12 weeks adjusted for baseline. RESULTS: A total of 315 women and 63 men were randomized and treated, and 332 participants (276 women, 56 men) completed the study. At the end of the study, extended-release oxybutynin was significantly more effective than tolterodine in each of the main outcome measures: weekly urge incontinence (P=.03), total incontinence (P=.02), and micturition frequency episodes (P=.02) adjusted for baseline. Both drugs improved symptoms of overactive bladder significantly from baseline to the end of the study as assessed by the 3 main outcome measures (P<.001). Dry mouth, the most common adverse event, was reported by 28.1% and 33.2% of participants taking extended-release oxybutynin and tolterodine, respectively (P=.32). Rates of central nervous system and other adverse events were low and similar in both groups. CONCLUSIONS: Extended-release oxybutynin was more effective than tolterodine as measured by end-of-study urge incontinence, total incontinence, and micturition frequency episodes. Both groups had similar rates of dry mouth and other adverse events.

Aged↗
PubMed2000

Localized biphasic changes in phosphatidylinositol-4,5-bisphosphate at sites of phagocytosis.

Phagocytosis requires localized and transient remodeling of actin filaments. Phosphoinositide signaling is believed to play an important role in cytoskeletal organization, but it is unclear whether lipids, which can diffuse along the membrane, can mediate the focal actin assembly required for phagocytosis. We used imaging of fluorescent chimeras of pleckstrin homology and C1 domains in live macrophages to monitor the distribution of phosphatidylinositol-4,5-bisphosphate (4,5-PIP(2)) and diacylglycerol, respectively, during phagocytosis. Our results reveal a sequence of exquisitely localized, coordinated steps in phospholipid metabolism: a focal, rapid accumulation of 4,5-PIP(2) accompanied by recruitment of type Ialpha phosphatidylinositol phosphate kinase to the phagosomal cup, followed by disappearance of the phosphoinositide as the phagosome seals. Loss of 4,5-PIP(2) correlated with mobilization of phospholipase Cgamma (PLCgamma) and with the localized formation of diacylglycerol. The presence of 4, 5-PIP(2) and active PLCgamma at the phagosome was shown to be essential for effective particle ingestion. The temporal sequence of phosphoinositide metabolism suggests that accumulation of 4,5-PIP(2) is involved in the initial recruitment of actin to the phagocytic cup, while its degradation contributes to the subsequent cytoskeletal remodeling.

Actins↗
PubMed2000

Apparent involvement of the A(2A) subtype adenosine receptor in the anti-inflammatory interactions of CGS 21680, cyclopentyladenosine, and IB-MECA with human neutrophils.

This study was undertaken to identify the adenosine receptor (AR) subtypes which down-regulate the proinflammatory activities of human neutrophils, as well as the involvement of adenosine 3',5'-cyclic monophosphate (cAMP) and its relationship to cellular handling of Ca(2+) in mediating these effects. Neutrophils were treated with varying concentrations (0.01-1 microM) of AR agonists operative at A(1) (N(6)-cyclopentyladenosine, CPA), A(2A) (2(4-[(2-carboxyethyl)phenyl]ethylamino)-5'-N-ethylcarboxamidoadenosi ne, CGS 21680), and A(3) (N(6)-(3-iodobenzyl-5'-N-methylcarbamoyladenosine, IB-MECA) receptors, after which they were activated with the chemoattractant, N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP, 1 microM). Intracellular cAMP, superoxide, and elastase were assayed using radioimmunoassay, lucigenin-enhanced chemiluminescence (LECL), and colorimetric procedures, respectively, while changes in the concentrations of cytosolic Ca(2+) were monitored by fura-2-based spectrofluorimetry. CGS 21680, at all concentrations tested, inhibited superoxide production in a dose-related manner, while CPA and IB-MECA were effective only at the highest concentrations tested (0.5-1 microM). The release of elastase from activated neutrophils was also inhibited by all three AR agonists, but was more sensitive to CGS 21680 and IB-MECA than was superoxide production. The inhibitory effects of all 3 agonists on superoxide production and elastase release were associated with accelerated clearance of Ca(2+) from the cytosol of activated neutrophils, and were effectively neutralized by pretreatment of the cells with the highly selective A(2A)R antagonist, ZM 241385 (4-(2-[7-amino-2-(2-furyl)[1, 2,4]triazolo[2,3-a][1,3,5]triazin-5yl amino]ethyl)phenol). Increased cAMP was detected in neutrophils treated with CGS 21680 and IB-MECA (1 microM). These data support the involvement of the A(2A)R subtype in the suppression of superoxide production and degranulation by activated human neutrophils, probably by cAMP-mediated alterations in Ca(2+) handling.

Adenosine↗
PubMed2000

AIDS in a new millennium.

As we enter the new millennium the world is still facing the challenge of responding to the AIDS pandemic. A new report from the Joint United Nations Programme on HIV/AIDS presents the latest statistics on prevalence, spread, and impact of the disease. In their Perspective, Schwartländer and his colleagues discuss the newly released statistics and the strategies needed to combat the further spread of HIV/AIDS and to reduce prevalence in the most severely affected countries.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Theiler's murine encephalomyelitis virus induces rapid necrosis and delayed apoptosis in myelinated mouse cerebellar explant cultures.

Infection with the Daniel strain of Theiler's murine encephalomyelitis (TMEV-DA) virus induces persistent demyelinating lesions in mice and serves as a model for multiple sclerosis. During the acute phase of the disease, however, viral infection leads to cell death in vivo. Viral-induced death may result directly from viral infection of neural cells, or indirectly, by activation of the immune system. To examine the direct effects of TMEV infection on neural cells, myelinated explant cultures of the murine cerebellum were infected with 10(5) pfu of TMEV-DA for periods ranging from 1 to 72 h. Our results indicate that TMEV-DA replicates in cultured neural tissue. Initially, viral antigen is localized to a few isolated neural cells. However, within 72 h antigen was observed in multiple foci that included damaged cells and extracellular debris. Viral infection led to a rapid and cyclical induction of necrosis with a time period that was consistent with the lytic phase of the viral life-cycle. Simultaneously, we observed an increase in apoptosis 48 h post-infection. Electron micrographic analysis indicated that viral-infected cultures contained cells with fragmented nuclei and condensed cytoplasm, characteristic of apoptosis. The localization of apoptosis to the cerebellar granule cell layer, identified these cells as presumptive granule neurons. Viral infection, however, did not lead to myelin damage, though damaged axons were visible in TMEV-infected cultures. These results suggest that during the acute phase of infection, TMEV targets neural cells for apoptosis without directly disrupting myelin. Myelin damage may therefore result from the activation of the immune system.

Animals↗
PubMed2000

Medical therapy, symptoms, and the distress the cause: relation to quality of life in patients with angina pectoris and/or hypertension.

BACKGROUND: Adverse events during drug therapy can be assessed through measurement of 2 features: their frequency and their severity. Their severity, in turn, can be measured by assessing the distress that they cause. Our goal was to relate the magnitude of the distress induced by treatment with calcium-channel blocking agents to the change in quality of life assessed through psychosocial instruments in patients treated with calcium-channel blocking agents, either for hypertension or for angina pectoris. METHODS: Four hundred seventy-five patients with angina pectoris were randomized to double-blind treatment with PPR (physiological pattern release) verapamil hydrochloride, amlodipine besylate, amlodipineatenolol combination, or placebo. In addition, 557 hypertensive patients were randomized either to PPR verapamil or nifedipine GITS (gastrointestinal system). Both studies were double-blind. RESULTS: Significant differences in treatment of angina pectoris or hypertension, were not found between the regimens. Overall quality of life also failed to show a significant difference in either group. In both groups, however, remarkable concordance was found between the degree of distress associated with specific symptoms and a change in quality of life. An unchanged, stable symptom distress was associated with a significant improvement in the quality of life of about 0.1 SD. Improvement or erosion of symptom distress represented by 1 step was associated with a 0.1- to 0.2-SD change. The extreme change in symptom distress was associated with a substantially larger change in global quality of life. CONCLUSIONS: The magnitude of symptom distress or relief associated with symptoms in 2 patient populations correlated strongly with a shift in quality of life. The assessment of distress associated with symptoms provides valuable additional information on drug therapy.

Adult↗
PubMed2000

Antibiotic prescribing for dental conditions: general medical practitioners and dentists compared.

OBJECTIVE: To compare the level of prescribing and types of antibiotics prescribed for dental problems by general medical practitioners and dentists. DESIGN: Secondary analysis of standard consultation data and prescription records from four different settings. SETTING: 30 participating general practices in the General Practice Morbidity Database for Wales in 1996. SUBJECTS: 1,185 attendances for tooth-related problems, at 30 participating practices in the General Practice Morbidity Database for Wales in 1996. Standard consultation records from a GDP emergency dental rota, and two weekend emergency dental clinics: one in a health centre, the other in a dental hospital. RESULTS: More than two thirds (68%) of attendances at general medical practices for tooth-related problems resulted in a prescription for antibiotics. In contrast less than a third (28%) of patients seen by a GDP rota, about half (52%) of patients at a weekend emergency clinic in a health centre, and just more than a third (38%) of patients attending the dental hospital clinic received antibiotics. General medical practitioners were also more likely to prescribe broad-spectrum antibiotics than dentists. CONCLUSION: For acute dental problems general medical practitioners are more likely to prescribe antibiotics than dentists. There also appear to be inter-professional differences in the tendency to prescribe broad spectrum antibiotics. Initiatives to rationalise prescribing for dental conditions may need to target doctors as well as dentists.

Anti-Bacterial Agents↗
PubMed2000

Crystal structures of ligand complexes of P450eryF exhibiting homotropic cooperativity.

Several mammalian cytochrome P450 (P450) isoforms demonstrate homotropic cooperativity with a number of substrates, including steroids and polycyclic aromatic hydrocarbons. To identify structural factors contributing to steroid and polycyclic aromatic hydrocarbon binding to P450 enzymes and to determine the location of the allosteric site, we investigated interactions of the macrolide hydroxylase P450eryF from Saccharopolyspora erythraea with androstenedione and 9-aminophenanthrene. Spectroscopic binding assays indicate that P450eryF binds androstenedione with an affinity of 365 microM and a Hill coefficient of 1.31 +/- 0.6 and coordinates with 9-aminophenanthrene with an affinity of 91 microM and a Hill coefficient of 1.38 +/- 0.2. Crystals of complexes of androstenedione and 9-aminophenanthrene with P450eryF were grown and diffracted to 2.1 A and 2.35 A, respectively. Electron density maps indicate that for both complexes two ligand molecules are simultaneously present in the active site. The P450eryF/androstenedione model was refined to an r = 18.9%, and the two androstenedione molecules have similar conformations. The proximal androstenedione is positioned such that the alpha-face of carbon-6 is closest to the heme iron, and the second steroid molecule is positioned 5.5 A distal in the active site. The P450eryF/9-aminophenanthrene model was refined to an r = 19.7% with the proximal 9-aminophenanthrene coordinated with the heme iron through the 9-amino group and the second ligand positioned approximately 6 A distal in the active site. These results establish that homotropic cooperativity in ligand binding can result from binding of two substrate molecules within the active site pocket without major conformational changes in the protein.

Bacterial Proteins↗