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Biomedical subjects

A Arnold

Publications and source records attributed to A Arnold.

244 records · Page 14Linked to original sources
PubMedDate not supplied

Reliability of cognitive tests used in Alzheimer's disease.

Assessment of cognitive status is a key component of monitoring Alzheimer's patients during the course of their illness. The reliability of a cognitive test is a measure of its reproducibility under replicate conditions. In the classical setting, reliability is defined in three ways: the ratio of the variance of the true scores to the variance of the observed scores; the correlation of observed scores on two parallel forms of the test, and the square of the correlation between the observed score and the true score. In the classical case of independence of true scores and measurement errors, the three definitions are equivalent. Estimation of reliability through analysis of variance techniques and construction of confidence intervals is accomplished when the true scores and errors are normally distributed. This paper examines a non-parametric, probabilistic estimate of reliability as the probability that, given a parallel test, the second set of scores has the same ranking as the first set. In the classical case there is a monotonic relationship between this measure and the reliability. This measure is also linked to Kendall's tau. The performance of the probabilistic measure is compared with the traditional measures in a variety of models, including those with bounded scales, and those with skewed distributions. The ideas are extended to the case of the reliability of change scores and to biased estimators of true scores. In this context truncation models and Bayes estimates of true scores are considered.

Aged↗
PubMedDate not supplied

Phase II study of troxacitabine (BCH-4556) in patients with advanced non-small-cell lung cancer.

Troxacitabine. a promising new L-nucleoside, inhibits DNA polymerase and leads to complete DNA chain termination. The National Cancer Institute of Canada Clinical Trials Group (NCIC-CTG) conducted a phase II study to assess the efficacy and toxicity of troxacitabine in untreated patients with advanced non-small-cell lung cancer (NSCLC). Previously untreated patients were eligible if they had inoperable stage IIIB or IV NSCLC, ECOG PS < or = 2, adequate hematology and biochemistry, and at least one bidimensionally measurable lesion. Patients with prior malignancy or brain metastases were excluded. Troxacitabine (10 mg/m(2)) was administered intravenously over 30 minutes every 3 weeks. Between June 1999 and May 2000, 17 eligible patients received treatment. Patient characteristics included: median age 64 years; female 41%; stage IV (94%); PS 0 (12%), 1 (59%), and 2 (29 %), 3 or more disease sites (59%). In 17 patients, there were 8 stable disease, 9 disease progression, and no objective responses. Median duration of stable disease was 3.6 months (range = 2.0-7.1). A total of 56 cycles were administered (median = 3), and 88% of patients received 90% or more of the planned dose intensity. The majority (82%) of patients experienced skin rash. Hematologic and biochemical toxicities, grade 3/4 (%) were: granulocytopenia (41), anemia (12), thrombocytopenia (6), and hyperglycemia (6). Troxacitabine appears to have little activity in NSCLC in the dose and schedule tested.

Aged↗
PubMedDate not supplied

Treatment of malignant superior vena cava obstruction: metal stents or radiation therapy.

PURPOSE: The results of treating malignant superior vena cava obstruction by means of percutaneous self-expanding stent insertion or by means of radiation therapy were compared. PATIENTS AND METHODS: Seventy-six patients with malignant superior vena cava obstruction who were treated by stent insertion were studied prospectively and 25 patients who were treated by radiation therapy were studied retrospectively. A superior vena cava obstruction score was devised to measure treatment effectiveness. Speed of symptom relief and complications were recorded. End points in the study were recurrent obstruction or death. Asymptomatic survival times were compared by log rank and Mann Whitney tests of significance, as well as Kaplan-Meier analysis. A subgroup of 26 patients who were treated by stent placement only were compared with the radiation therapy group and analyzed separately. RESULTS: There were seven complications in the overall stent group, one in the stent-only group, and 25 in the radiation therapy group. Stent insertion provided faster relief of symptoms and significantly greater improvement in the superior vena cava obstruction score than radiation therapy (P < .001, Mann-Whitney U test). A Kaplan-Meier analysis of asymptomatic survival demonstrated that significantly fewer patients in the overall and stent-only groups developed recurrent symptoms (P = .0005 and .001, respectively, log rank test). CONCLUSION: This study suggests that percutaneous stent insertion in malignant superior vena cava obstruction fulfills the requirements of a palliative procedure significantly better than radiation therapy and that it should be the procedure of first choice.

Adult↗
PubMedDate not supplied

Critical evaluation of models developed for monitoring an industrial submerged bioprocess for antibiotic production using near-infrared spectroscopy.

Near-infrared spectroscopy (NIRS) is known to have potential for cost-effective monitoring of bioprocesses. Although this has been demonstrated in many instances and several models have been reported, information regarding the complexity of models required and their utility over extended periods of time is lacking. In the present study, the complexity of the models required for the NIRS prediction of substrate (oil) and product (tylosin) concentration in an industrial bioprocess that employs a physicochemically heterogeneous medium for antibiotic production was assessed. Measurements made by both the diffuse reflectance and transmittance modes were investigated. SEP values for the prediction of the analytes averaged 5% or less, for the successful models, when evaluated using an external validation set, 2 years after the initial model development exercise. Diffuse reflectance measurements showed poorer results, compared to transmittance measurements, especially for monitoring tylosin. In general, this investigation provides evidence to support the fact that models built for the prediction of analytes in a commercial bioprocess that employs a physicochemically complex production medium can be robust in performance over an extended period of time and that simple models based on fewer terms or latent variables can perform well, even in the context of matrices that are relatively complex. It also indicates that sample presentation is likely to be a critical factor in the successful application of NIRS in bioprocess monitoring, which merits further detailed investigation.

Anti-Bacterial Agents↗
PubMedDate not supplied

The effects of transdermal estradiol alone or with cyclical dydrogesterone on markers of cardiovascular disease risk in postmenopausal women with type 2 diabetes: a pilot study.

The objective of this open, longitudinal, controlled study was to assess the effect of transdermal estradiol alone or combined with cyclical dydrogesterone on the markers of cardiovascular disease (CVD) risk in postmenopausal women with type 2 diabetes. The control group consisted of postmenopausal diabetic women who declined menopausal hormone replacement therapy (HRT). Twenty-eight postmenopausal women (19 on HRT and 9 controls) with type 2 diabetes were followed up for 12 months. From the active treatment group 14 women with a uterus in situ had 80 microg/24 hr transdermal estradiol (Fematrix 80; Solvay Healthcare Ltd, Southampton, UK) and oral dydrogesterone 10 mg daily for the first 12 days of the calendar month, whereas 5 women with previous hysterectomy had 80 microg/24 hr transdermal estradiol (Fematrix 80) alone. CVD risk markers were measured before and at regular intervals after starting HRT. The main outcome measures were weight, systolic and diastolic blood pressure, fasting plasma glucose, glycated hemoglobin (HbA1c), glucose/insulin ratio, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides, lipoprotein (a), high-sensitivity C-reactive protein (hs-CRP), fibrinogen, and endothelin-1. Transdermal estradiol with or without dydrogesterone in women with type 2 diabetes did not adversely affect any of the measured markers of cardiovascular risk. There was a significant decrease in HbA1c, total cholesterol, and LDL cholesterol at 6 months in women receiving HRT. Some of the cardiovascular disease risk markers may improve in postmenopausal women with type 2 diabetes with transdermal estradiol. This effect may have important clinical implications and it deserves further investigation in appropriately designed trials.

Administration, Cutaneous↗
PubMedDate not supplied

Neuromotor function in rats during subchronic dietary exposure to triphenyl phosphate.

The possibility that dietary exposure to triphenyl phosphate (TPP) may result in detectable neuromotor dysfunction was investigated. Young male Sprague-Dawley rats were fed diets containing TPP at levels of 0, 0.25, 0.50, 0.75 or 1.0% for 4 months. At approximately monthly intervals, a battery of behavioral tests was administered to assess different facets of neuromotor function including motility, balance, coordination and muscular strength. Treatment-related decrements in growth, in the absence of changes in food consumption, were found at all dietary levels above 0.25%. However, none of the behavioral measures used in this study were affected by the dietary treatment. It was concluded that there is no evidence of neuromotor toxicity following subchronic dietary exposure to TPP in the rat.

Animals↗