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Biomedical subjects

S A Taylor

Publications and source records attributed to S A Taylor.

At least 19 recordsLinked to original sources
PubMed1999

Risk of venous thromboembolism associated with the common hereditary haemochromatosis Hfe gene (C282Y) mutation.

A high prevalence of a common mutation in the Hfe gene (C282Y) has recently been reported in patients with the factor V Leiden mutation and a history of thrombosis. The aim of this study was to estimate the relative risk of venous thromboembolism in a large case-control study. 56/481 patients (11.6%) and 57/497 controls (11.5%) were heterozygous for the C282Y allele giving an odds ratio of 1.02 (95%CI 0.69-1.51). 12/81 patients with the factor V Leiden mutation were heterozygous for the C282Y allele compared to 1/13 controls, odds ratio 2.09 (95%CI 0.25-17.6). An analysis of a further group of patients and controls selected for the factor V Leiden mutation did not indicate a higher prevalence of the C282Y allele in symptomatic patients, odds ratio 0.17 (95%CI 0.34-0.81). This study does not support the hypothesis that the C282Y allele is an additional risk factor for venous thrombosis in patients with the factor V Leiden mutation.

Adolescent↗
PubMed1998

Concurrent cisplatin, prolonged oral etoposide, and vincristine plus chest and brain irradiation for limited small cell lung cancer: a phase II study of the Southwest Oncology Group (SWOG-9229).

PURPOSE: The primary objectives of the study were to evaluate the efficacy and safety of prolonged oral (PO) etoposide as part of cisplatin-based chemotherapy plus concurrent chest/brain irradiation induction, followed by CAV consolidation, in the treatment of patients with limited-stage small cell lung cancer (SCLC-LD) within a cooperative group setting. METHODS AND MATERIALS: Fifty-six eligible patients with SCLC-LD received three 28-day cycles of cisplatin 50 mg/m2 i.v. (days 1, 8; 29, 36; and 57, 64), PO etoposide 50 mg/m2 (days 1-14, 29-42, and 57-70), and vincristine 2 mg i.v. (days 1, 29, and 57). Thoracic irradiation (TRT) was administered at 1.8 Gy in 25 daily fractions to a total dose of 45 Gy via an AP:PA arrangement, to begin concomitantly with induction chemotherapy. Prophylactic cranial irradiation (PCI) was started on day 15 of induction therapy. Fifteen daily fractions of 2.0 Gy were administered to the entire brain to a total dose of 30 Gy to finish at approximately the same time as TRT. Two 21-day cycles of consolidation cyclophosphamide 750 mg/m2 i.v., doxorubicin 50 mg/m2 i.v., and vincristine 2 mg i.v. (all on days 1 and 22), were given beginning on day 106 or week 16, from the start of induction therapy. RESULTS: Among 56 eligible patients, 93% had SWOG performance status 0-1. All had adequate organ function and had not received prior therapy. The overall confirmed response rate was 46%, including 16% complete responders and 30% partial responders. After a minimum follow-up duration of 17 months, the Kaplan-Meier median progression-free (PFS) and overall survival (OS) were 10 and 15 months, respectively. Two-year survival is 28%. Only 28 of 56 patients (50%) completed chemotherapy per protocol, while 52 of 56 patients (93%) completed radiation per protocol. Eleven patients (20%) discontinued secondary to toxicity and two patients died from treatment. The major toxicity was hematologic. The two deaths were secondary to infection. Of the nonhematologic toxicities, there were 10 cases of pulmonary fibrosis (including one Grade 3) and six cases of pneumonitis (including one Grade 3). CONCLUSION: Concomitant chemoradiation with oral etoposide as part of a platinum-based chemotherapy and TRT induction regimen is toxic. The CR rate is not better than our prior best group-wide experience. The progression-free and overall survival are similar to published trials utilizing short-course i.v. etoposide. As in chemotherapy for extensive-stage SCLC, there is no apparent advantage to prolonged exposure to etoposide, and toxicity resulted in an inferior therapeutic index compared to programs with shortened exposure.

Administration, Oral↗
PubMed1998

Adverse effects of chronic low level lead exposure on kidney function--a risk group study in children.

BACKGROUND: Children have been considered a risk group for lead (Pb) toxicity, mainly because of neurophysiological or neuro-cognitive deficits following Pb exposure. Blood Pb levels (b-Pb) of 100 microg/l currently have been defined as the lowest adverse effect level. The aim of this study was to compare, with the help of urinary markers, the kidney function of children with b-Pb just above this threshold with that of unexposed children, to assess from a nephrological point of view whether the current threshold is justified and whether children really are a particularly vulnerable risk group in terms of Pb-induced kidney damage. METHODS: In a cross-sectional study, 112 children, either from unexposed areas (controls, n=50) or Pb-contaminated areas (n=62), the latter partly with a known history of elevated b-Pb, were examined. Twenty nine urinary or serum markers mostly related to the function or integrity of specific nephron segments were determined (e.g. filtered plasma proteins, tubular enzymes, tubular antigens, eicosanoids). RESULTS: b-Pb were 39+/-13 microg/l in controls and 133+/-62 microg/l in exposed children. The main findings were increased excretion rates of prostaglandins and thromboxane B2, epidermal growth factor, beta2-microglobulin and Clara cell protein in the exposed children. A relationship between b-Pb and the prevalence of values above the upper reference limits was observed. CONCLUSIONS: With the help of urinary markers, nephron segment-specific effects of chronic low-level Pb exposure could be detected in children. The pattern of effects on glomerular, proximal and distal tubular and interstitial markers was similar to that previously observed in adults. The changes, however, occur at lower b-Pb levels than in adults. The current threshold appears to be justified also from a nephrological point of view, and children can indeed be considered a special risk group.

Biomarkers↗
PubMed1998

Evaluation of topotecan in resistant and relapsing multiple myeloma: a Southwest Oncology Group study.

PURPOSE: Topotecan is a topoisomerase I inhibitor with antitumor activity against hematologic and solid tumor malignancies. We evaluated its activity in refractory and relapsing multiple myeloma patients who had received one prior chemotherapeutic regimen. PATIENTS AND METHODS: Toptecan 1.25 mg/m2/d was administered as a 30-minute infusion for 5 days repeated every 3 weeks. Granulocyte colony-stimulating factor (G-CSF) 5 microg/kg/d subcutaneously was administered after the first course of treatment if neutropenia was dose-limiting. RESULTS: Forty-six patients entered the study, with 43 patients eligible. The major toxicity was granulocytopenia with grade 3 or better occurring in 40 of 43 patients treated; 21 of 43 patients developed grade 3 or greater thrombocytopenia. Other significant toxicity included mild nausea in 23 patients and mild vomiting in 13 patients. The overall response rate (partial response or better) was 16% (95% confidence interval, 7% to 31%), with responses occurring in both relapsed and refractory patients. Responses have lasted 70 to 477+ days, with a median progression-free survival duration of 13 months and median survival time of 28 months. CONCLUSION: Topotecan has activity in refractory and relapsing multiple myeloma. Future investigation of topotecan in multiple myeloma including combination therapy and the study of other topoismerase I inhibitors is warranted.

Adult↗
PubMed1998

Interferon versus interferon plus prednisone remission maintenance therapy for multiple myeloma: a Southwest Oncology Group Study.

PURPOSE: We evaluated the vincristine, doxorubicin, and dexamethasone (VAD) regimen alone or with chemosensitizers for remission induction and interferon (IFN) versus IFN plus prednisone (IFN/P) for remission maintenance in previously untreated multiple myeloma. PATIENTS AND METHODS: Two hundred thirty-three patients were registered for remission-induction therapy with VAD or VAD plus the chemosensitizers verapamil and quinine. Patients who achieved remission were randomized to maintenance therapy with IFNalpha 3 MU in the evening three times weekly or IFN plus 50 mg of prednisone (IFN/P) on the morning after IFN until relapse. RESULTS: Two hundred twenty-nine patients were eligible for induction. Fatal toxicities in nine patients who received VAD plus verapamil and quinine led to closure of this arm after 47 registrations. Subsequently, all patients received VAD induction. Despite the high early mortality rate on VAD plus sensitizers, overall survival by induction arm did not differ for median or 5-year survival with approximately 40% of patients surviving 5 years. Eighty-nine eligible patients who achieved remission were randomized to maintenance. Patients who received IFN/P had improved progression-free survival (median, 19 v9 months for IFN; P = .008). After 48 months, progression-free survival on IFN/P was at the thirtieth percentile, whereas it was below the tenth percentile on IFN alone. Median survival from start of maintenance was long on both arms (57 months for IFN/P v 46 months for IFN; P = .36). CONCLUSION: IFN/Pwas more effective than IFN alone. Improved relapse-free survival may be attributable to IFN/P or to the use of prednisone for maintenance. This latter alternative is currently being studied.

Adult↗
PubMed1998

Randomized trial comparing cisplatin with cisplatin plus vinorelbine in the treatment of advanced non-small-cell lung cancer: a Southwest Oncology Group study.

PURPOSE: Cisplatin has played a major role in the treatment of non-small-cell lung cancer (NSCLC). This randomized trial was performed by the Southwest Oncology Group (SWOG) to determine whether the combination of vinorelbine and cisplatin has any advantage with regard to response rate, survival, and time to treatment failure over single-agent cisplatin in the treatment of patients with advanced NSCLC. METHODS: Between October 1993 and April 1995, 432 patients with advanced stage NSCLC were randomized to receive arm I (cisplatin 100 mg/m2 every 4 weeks) or arm II (cisplatin 100 mg/m2 every 4 weeks and vinorelbine 25 mg/m2 weekly). All patients were chemotherapy-naive, had performance status (PS) 0 or 1, and had adequate hematologic, renal, and hepatic function. RESULTS: Four hundred fifteen patients were eligible and assessable. On arm I (cisplatin), there was a 12% partial response rate. Arm II (cisplatin and vinorelbine) had a 26% response rate (2% complete responses and 24% partial responses, P = .0002). There was a statistically significant advantage with regard to progression-free survival (median, 2 v 4 months; P = .0001) and overall survival (median, 6 v 8 months; P = .0018) for the cisplatin and vinorelbine arm. One-year survival was 20% for cisplatin alone and 36% for the combination arm. There was more hematologic toxicity on arm II of the study (81% grades 3 and 4 granulocytopenia v 5% on arm I). Other toxicities, such as renal insufficiency, ototoxicity, and nausea and vomiting, and neuropathy were similar. CONCLUSION: The results of this study indicate that the combination of cisplatin and vinorelbine is a superior treatment when compared with single-agent cisplatin in the treatment of advanced NSCLC. Cisplatin and vinorelbine is the new standard for SWOG against which new therapies will be evaluated.

Adult↗
PubMed1998

Assessing physician/patient relationships in the presence of HIV/AIDS: an exploratory study.

The following study investigates the nature of the relationship between physicians and HIV/AIDS patients within the context of the rapidly evolving services/relationship marketing literatures. The emerging evidence suggests that service providers generally play a critical role in the development of positive consumer attitudes and behaviors, and that relationship marketing practices can contribute to the delivery of health services. However, to date, there appears little evidence supporting the efficacy of employing relationship marketing practices in relation to a target market of HIV/AIDS patients. This exploratory study contributes to the body of knowledge by more closely investigating the nature of the patient-physician relationship relative to HIV/AIDS patients' attitudes, marketing-related behaviors, and overall quality-of-life/life satisfaction judgments. The results of this study first suggest that HIV/AIDS patients use the expectancy disconfirmation model when evaluating the performance of their physician. A reliance on expectancy disconfirmation suggests the likely prevalent role of service quality perceptions and satisfaction judgments in evaluating their relationship with their physician. Second, the results appear to support the conclusion that the patient's evaluation of their physician relationship and subsequent behaviors (e.g., word-of-mouth) are directly related to the patient's general perception of received health services. Thus, the patient/physician relationship may play a particularly powerful role in determining patient (marketing related) outcomes relative to other health service settings. Third, a direct influence is supported between negative affective reactions by patients and subsequent outcome behaviors. This finding lends support for the potential efficacy of service recovery efforts when rendering treatment to HIV/AIDS patients. Finally, evidence is presented demonstrating the effect of positive perceptions of the patient/provider relationship on these patients' overall evaluation of their quality-of-life/life satisfaction. The managerial and research implications of this study are presented and discussed.

Attitude to Health↗
PubMed1997

The assessment of biomarkers to detect nephrotoxicity using an integrated database.

Groups of industrial workers exposed to heavy metals (cadmium, mercury, and lead) or solvents were studied together with corresponding control groups. The cohorts were collected from several European centers (countries). Eighty-one measurements were carried out on urine, blood, and serum samples and the results of these analyses together with questionnaire information on each individual were entered into a central database using the relational database package Rbase. After the completion of the database construction phase, the data were exported in a format suitable for analysis by the statistical package SAS. The potential value of each test as an indicator of nephrotoxicity was then assessed. Rigorous exclusion criteria were applied which resulted in the elimination of some tests and samples from the dataset. The measurable contributions of smoking, gender, metal exposure, and site were either singly or in combination assessed by biomarkers for nephrotoxicity. The parameters measured included three urinary enzymes, six specific proteins, total protein, two extracellular matrix markers, four prostaglandins and anti-GBM antibodies, and beta 2-microglobulin in serum. The most sensitive renal tests included the urinary enzymes N-acetyl-beta-D-glucosaminidase (NAG) and intestinal alkaline phosphatase (IAP), brush border antigens, and urinary low-molecular-weight proteins. Of the newer tests investigated the prostaglandins were the most promising. Different patterns of biomarker excretion were observed following exposure to lead, cadmium, or mercury. The dataset provides a unique repository of data which could provide the basis of an enlarging source of information on normal human reference ranges and on the effects of exposure to toxins and the use of biomarkers for monitoring nephrotoxicity.

Biomarkers↗
PubMed1997

Evidence that skewed X inactivation is not needed for the phenotypic expression of Aicardi syndrome.

Aicardi syndrome is a rare disorder characterized by absent corpus callosum, infantile spasms, and choriorentinal lacunae. It is sporadic in nature and affects only females, resulting in severe mental and physical handicap. It has been suggested that the disease is caused by a dominant X-linked mutation which occurs de novo in females, and is lethal in hemizygous male embryos. This mode of inheritance has been observed in a number of other rare syndromes. In these syndromes, when X inactivation is studied, a non-random pattern is usually found. We have studied the X inactivation pattern in ten female patients with Aicardi syndrome and their parents using the highly polymorphic, differentially methylated androgen receptor gene. The results showed an unexpected random X-inactivation pattern in these patients. Previous clinical and cytogenetic evidence suggests that Aicardi syndrome is caused by an X-linked dominant mutation, de novo in females and lethal in males. However, unlike most other known X-linked disorders inherited in this fashion, Aicardi syndrome patients have a normal (i.e., random) X-inactivation pattern. A number of possible explanations is proposed for this apparently contradictory evidence.

Abnormalities, Multiple↗
PubMed1997

Mutation of RET codon 768 is associated with the FMTC phenotype.

Multiple endocrine neoplasia type 2A (MEN 2A), type 2B (MEN 2B), and familial medullary thyroid carcinoma (FMTC) are inherited cancer syndromes resulting from mutations in the RET proto-oncogene. Missense mutations of five codons in exons 10 and 11 are found in both MEN 2A and FMTC families, while mutations at codon 768 in exon 13 have been identified in three FMTC families. We report here the results of mutation analysis on a large multi-generation family with multiple cases of medullary thyroid carcinoma (MTC) or C-cell hyperplasia and two individuals with isolated adrenal medullary hyperplasia. A mutation in exon 13, which alters codon 768 from a GAG (Glu) to a GAC (Asp), was found to segregate with the FMTC phenotype in this family but not with the adrenal medullary hyperplasia. These findings suggest that the codon 768 mutation does not predispose to adrenal medullary hyperplasia, but is an accurate predictor of the MTC phenotype in this family.

Carcinoma, Medullary↗
PubMed1997

Phase II trial of paclitaxel and granulocyte colony-stimulating factor in patients with pancreatic carcinoma: a Southwest Oncology Group study.

PURPOSE: Pancreatic cancer is difficult to treat, with most patients surgically unresectable at the time of diagnosis. Radiotherapy and chemotherapy can offer palliation, but more effective therapy is needed. This trial evaluated the effects of an aggressive schedule of paclitaxel given with granulocyte colony-stimulating factor (G-CSF) to patients with advanced pancreatic cancer. PATIENTS AND METHODS: All patients were required to have a histologic diagnosis of pancreatic adenocarcinoma with measurable disease and no prior chemotherapy or radiation therapy. Patients had to have performance status of 0 to 2, pretreatment absolute granulocyte count > or = 1,500/microL, and platelet count greater than or equal to the institutional lower limit of normal. Following pretreatment with dexamethasone, diphenhydramine, and cimetidine, patients received paclitaxel at a dose of 250 mg/m2 by 24-hour infusion on day 1, repeated every 21 days. G-CSF was given at a dose of 5 microg/kg/d on days 3 to 18 or until two consecutive absolute neutrophil counts (ANCs) > or = 10,000/microL were obtained. Doses of paclitaxel were modified depending on nadir counts. RESULTS: Forty-five patients were entered onto this study, with six ineligible. For the 39 eligible patients, there was one complete response (CR) and two partial responses (PRs), five stable/no responses, 23 increasing disease, two early deaths, and six patients whose assessment was inadequate to determine response. The response rate was therefore three of 39 or 8% (95% confidence interval [CI], 2% to 21%). The median survival time for the 39 eligible patients was 5 months. The most common toxicities were anemia, leukopenia/granulocytopenia, malaise/fatigue, nausea/vomiting, alopecia, thrombocytopenia, paresthesias, and liver function abnormalities. There was one death due to sepsis. CONCLUSION: Single-agent paclitaxel in this dose and schedule has minimal activity in pancreatic adenocarcinoma patients.

Adenocarcinoma↗
PubMed1997

Patient satisfaction and service quality in the formation of customers' future purchase intentions in competitive health service settings.

The following study provides evidence that the relationship between quality perceptions and satisfaction judgements in the formation of future purchase intentions may be very different in health service settings relative to other service settings. The study investigates Taylor and Baker's (1994) assertion that satisfaction judgements moderate the quality-->purchase intention relationship by testing the research model in both for-profit and not-for-profit hospital settings. The results of this study first support the growing view that satisfaction judgements are more closely related to outcome behaviors than quality perceptions in hospital settings. The results further support the assertion that the formation of important consumer outcomes, such as future purchase intentions, appears to be different for health services. Thus, health service managers are cautioned to empirically test models in the literature specific to their own competitive setting. The managerial and research implications of the reported study are presented and discussed.

Choice Behavior↗
PubMed1996

Isolation of pepsin-resistant laminin fragments from human placenta: effect on epithelial cells cultured from the kidneys of patients with autosomal dominant polycystic kidney disease (ADPKD).

Laminin isolated from human placenta was subjected to prolonged pepsin digestion. Seven peptide fragments (designated N1 to N7) were separated by ion-exchange chromatography and gel filtration and characterised by SDS-polyacrylamide gel electrophoresis and immunoblotting. The molecular size of the laminin fragments varied from approx. 900,000 (N1) to 28,000 (N7). Epithelial cells obtained from normal kidneys and patients with autosomal dominant polycystic kidney disease (ADPKD) were cultured. The incorporation of [3H]thymidine was measured over 96 h to determine the effect of the addition of the different fragments and whole laminin from EHS tumour to the cells. The rate of growth of both normal and polycystic cells was increased in the presence of the laminin fragments but this effect was more pronounced in the ADPKD cells.

Cell Division↗
PubMed1996

Evaluation of topotecan in patients with recurrent for metastatic squamous cell carcinoma of the head and neck. A phase II Southwest Oncology Group study.

Twenty-nine patients with persistent, recurrent and/or metastatic squamous cell carcinoma of the head and neck were treated daily for five days at three-week intervals with topotecan 1.5 mg/m2. Four patients received prior chemotherapy, 23 prior surgery and 29 prior radiation therapy. Of the 29 eligible patients, 8 patients were not evaluable for response and were assumed to be non-responders. Of the remaining 21 evaluable patients, there were zero responses (0%, 95% confidence interval [0,.12]). The most common toxicities were myelosuppression, dyspnea and malaise/fatigue/lethargy. Topotecan has limited activity in advanced head and neck cancer with this dose and schedule.

Adult↗
PubMed1996

Multiple source localization using genetic algorithms.

We present a new procedure for localizing simultaneously active multiple brain sources that overlap in both space and time on EEG recordings. The source localization technique was based on a spatio-temporal model and a genetic algorithm search routine. The method was successfully applied to the localization of two dipole sources from several sets of simulated potentials with various signal-to-noise ratios (SNR). The different SNR values resembled evoked responses and epileptic spikes as commonly seen in the laboratory. Results of the simulation studies yielded localization accuracy ranging from 0.01 to 0.07 cm with an SNR of 10; from 0.02 to 0.26 cm with an SNR of 5; and from 0.06 to 0.73 cm when the SNR was equal to 2. Additionally, two sets of simulations were based on the dipole arrangements and time activities of data obtained during electrical stimulation of the median nerve in human subjects. These studies yielded localization accuracy within 0.1 cm. We also studied the localization accuracy of the algorithm using a physical model incorporating potential measurements of two current dipoles embedded in a sphere. In this situation the algorithm was successful in localizing the two simultaneously active sources to within 0.07-0.15 cm.

Algorithms↗