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James Anderson

Publications and source records attributed to James Anderson.

At least 19 recordsLinked to original sources
PubMed2007

One- and two-stage designs for phase II window studies.

The primary goal of phase II window studies in cancer is testing new single agents or combination therapies for newly diagnosed patients who are less likely to have multiple-drug-resistant tumours than the typical phase II patients who have failed one or more chemotherapeutic regimens. In addition, by utilizing newly diagnosed patients, one can assess the responsiveness in a population more representative of where the phase II agent might be applied in a true phase III setting. In general, the outcome of a patient on a phase II window study can be categorized as response, stable disease, or early disease progression. Phase II window studies sometimes require early stopping rules for both insufficient response rate and excessive early progression rates. In this paper, one-stage and two-stage designs for phase II window studies are developed, requiring the monitoring of two rates. It is shown that the power function is monotone in response rate and early disease progression rate. Consequently, the significance level and power are easy to compute. Computational procedures are described and examples are provided. The proposed method can be applied to other studies with categorical outcomes.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2007

In vivo biostability of polyether polyurethanes with fluoropolymer and polyethylene oxide surface modifying endgroups; resistance to metal ion oxidation.

Polyether polyurethanes are subject to oxidation catalyzed by, and through direct (redox) reaction with transition metal ions (metal ion oxidation, MIO). The source of the ions is corrosion of metallic parts within an implanted device. A Shore 80A polyether polyurethane was modified with fluoropolymer (E80AF) or polyethylene oxide (E80AP) surface modifying end groups (SME). The SME migrates to the surface to form a covalently bonded monolayer, while maintaining the bulk properties of the polyurethane. In vitro tests in H(2)O(2) solution indicated that both SME's accelerated MIO. Tubing samples containing cobalt mandrels were implanted in the subcutis of rabbits for up to 2 years. In vivo, E80AF significantly slowed the rate of visible degradation, but did not prevent MIO. E80AP had virtually identical visual performance to the unmodified control in vivo. Infrared spectroscopy and molecular weight correlated well with visual appearance. When cracks were seen, polyether soft segment oxidation was occurring. Both E80AP and the control developed severe loss of molecular weight in vivo. The changes were much less severe for E80AF. Thus, contrary to in vitro test results, the PEO SME had no effect at all on MIO resistance, while the fluoropolymer SME produced a significant improvement in biostability.

Animals↗
PubMed2006

In vivo biostability of shore 55D polyether polyurethanes with and without fluoropolymer surface modifying endgroups.

Polyether polyurethanes are subject to autooxidation and environmental stress cracking (ESC) because of interactions with lysosomal oxygen-free radicals. Oxidation can also be catalyzed by and caused by direct (redox) reaction with transition metal ions (metal ion oxidation, MIO). The source of the ions is corrosion of metallic parts within an implanted device. A previous study on a Shore 80A polyether polyurethane modified with fluoropolymer surface modifying end groups demonstrated improved biostability over unmodified controls. We predicted that this could be extrapolated to the inherently more biostable Shore 55D version (E55DF). While it is difficult to demonstrate significant biodegradation in the harder polymers within a reasonable time frame, we did see excellent biologic autooxidation and ESC resistance for both E55DF and its unmodified Shore 55D (P55D) control. E55DF was slightly, but significantly more resistant to MIO than P55D. This was particularly evident in molecular weight distributions with P55D exhibiting a large decrease in number average molecular weight compared to no change for E55DF. Both were markedly superior to the softer Shore 80A control. It does appear that one can extrapolate accelerated in vivo biostability results with the softer polymers to their harder analogues.

Animals↗
PubMed2006

In vivo biostability of polyether polyurethanes with fluoropolymer surface modifying endgroups: resistance to biologic oxidation and stress cracking.

A series of Shore 80A polyether polyurethanes were synthesized with from 0 to 6% fluoropolymer surface modifying endgroups (SME) to provide the bulk properties of the polyurethane with the surface properties of the fluoropolymer. It was theorized that the fluoropolymer would migrate to the surface, forming a monolayer barrier to the oxidants and crack-driving agents released by macrophages and foreign body giant cells in vivo. In a 12-week biostability screening test, samples strained to 400% elongation appeared to be highly stable. In a longer-term study, the fluoropolymer SME significantly delayed, but did not completely prevent the onset of microcracking and the development of environmental stress cracking in strained samples. Even so, the 4 and 6% SME polymers explanted at 2 years performed significantly better than the control. FTIR analysis did not correlate with SME concentration, but increased hydrogen-bonding index and loss of aliphatic ether (autoxidation) did correlate with the visual appearance and density of microcracks. Significant molecular weight reductions were seen for the SME-free control, but were small (within instrumental error) for the polymers with SME. The use of fluoropolymer as a SME does appear to be warranted as a means to improve polyether polyurethane biostability.

Animals↗
PubMed2006

Analysis of prognostic factors in patients with nonmetastatic rhabdomyosarcoma treated on intergroup rhabdomyosarcoma studies III and IV: the Children's Oncology Group.

PURPOSE: The outcome for localized rhabdomyosarcoma (RMS) or undifferentiated sarcoma (UDS) is affected by age, histology, primary anatomic site, extent of disease, and therapy. PATIENTS AND METHODS: We evaluated patient and disease characteristics for their ability to predict outcome for patients with nonmetastatic RMS or UDS treated on Intergroup Rhabdomyosarcoma Study (IRS) -III (1984 to 1991) or IRS-IV (1991 to 1997). RESULTS: The estimated 5-year failure-free survival (FFS) rate was 90% for patients with embryonal RMS (ERMS) stage 1, group I or IIa; stage 2, group I; or group III orbit. The estimated 5-year FFS rate was 87% for patients with ERMS stage 1, group IIb or IIc; stage 1, group III nonorbit; stage 2, group II; and stage 3, group I or II; and 73% for patients with ERMS stage 2 or 3, group III. The estimated 5-year FFS rate was poor for patients with stage 2 or 3, group III ERMS with invasive (T2) tumors who were age younger than 1 year or 10 years or older (56%) and patients with stage 2 or 3, group III extremity primary tumors (43%). Overall, outcomes for patients with alveolar RMS (ARMS) or UDS were worse than for patients with ERMS. However, the 5-year FFS rate was good for patients with ARMS/UDS at favorable sites with group I or II (80%) or group III (76%) disease. The FFS rate was poorer for patients with ARMS/UDS at unfavorable sites with group I or II (66%) or group III (45%) disease. The estimated 5-year FFS rate was 31% for patients with group III ARMS/UDS at unfavorable sites with regional lymph node disease, which is similar to metastatic RMS. CONCLUSION: Patient and disease characteristics identify distinct subsets with different outcomes, allowing the Soft Tissue Sarcoma Committee of the Children's Oncology Group to refine risk-adapted therapy assignment.

Adolescent↗
PubMed2006

In vivo biostability of polysiloxane polyether polyurethanes: resistance to biologic oxidation and stress cracking.

Polyether polyurethanes are extremely interesting for use in implantable devices. They are, however, susceptible to autoxidative degradation and stress cracking. One approach to improving biostability is to replace some of the polyether with polysiloxane. Shore 80A polyether polyurethanes with 20% (PS-20) and 35% (PS-35) polysiloxane were strained to 400% elongation and implanted in rabbits. Twelve weeks implant showed that both were significantly more biostable than their polysiloxane-free controls. After 18 months implant, PS-20 developed some localized tensile fractures. PS-35 showed no sign of visual damage. Infrared surface analysis does not allow direct evaluation of autoxidation because the Si--O--Si stretch peaks mask the polyether bands. Secondary indicators suggest possible very slight autoxidation of both PS-20 and PS-35 surfaces, but not enough to develop cracks. The polysiloxane-free controls did show substantial infrared evidence of autoxidation. Molecular weights of long-term PS-20 and PS-35 explants were negligibly lower. In comparison, the polysiloxane-free control suffered 35% molecular weight loss. Positive and negative controls performed as expected. PS-20 is recommended for devices that do not sustain high fixed loads. PS-35 is dramatically more biostable than its unmodified polyether analogues and is recommended for use in chronically implantable devices.

Animals↗
PubMed2006

Perfusion-CT assessment of infarct core and penumbra: receiver operating characteristic curve analysis in 130 patients suspected of acute hemispheric stroke.

BACKGROUND AND PURPOSE: Different definitions have been proposed to define the ischemic penumbra from perfusion-CT (PCT) data, based on parameters and thresholds tested only in small pilot studies. The purpose of this study was to perform a systematic evaluation of all PCT parameters (cerebral blood flow, volume [CBV], mean transit time [MTT], time-to-peak) in a large series of acute stroke patients, to determine which (combination of) parameters most accurately predicts infarct and penumbra. METHODS: One hundred and thirty patients with symptoms suggesting hemispheric stroke < or =12 hours from onset were enrolled in a prospective multicenter trial. They all underwent admission PCT and follow-up diffusion-weighted imaging/fluid-attenuated inversion recovery (DWI/FLAIR); 25 patients also underwent admission DWI/FLAIR. PCT maps were assessed for absolute and relative reduced CBV, reduced cerebral blood flow, increased MTT, and increased time-to-peak. Receiver-operating characteristic curve analysis was performed to determine the most accurate PCT parameter, and the optimal threshold for each parameter, using DWI/FLAIR as the gold standard. RESULTS: The PCT parameter that most accurately describes the tissue at risk of infarction in case of persistent arterial occlusion is the relative MTT (area under the curve=0.962), with an optimal threshold of 145%. The PCT parameter that most accurately describes the infarct core on admission is the absolute CBV (area under the curve=0.927), with an optimal threshold at 2.0 ml x 100 g(-1). CONCLUSIONS: In a large series of 130 patients, the optimal approach to define the infarct and the penumbra is a combined approach using 2 PCT parameters: relative MTT and absolute CBV, with dedicated thresholds.

Adult↗
PubMed2006

In vivo biostability of polysiloxane polyether polyurethanes: resistance to metal ion oxidation.

Polyether polyurethanes are subject to oxidation catalyzed by and through direct (redox) reaction with transition metal ions (cobalt), released by corrosion of metallic parts in an implanted device. Replacing part of the polyether with polysiloxane appears to reduce susceptibility to metal ion oxidation (MIO). In vitro studies indicated that polyurethanes containing 20-35% polysiloxane (PS-20 and PS-35) are about optimum. We implanted tubing samples containing cobalt mandrels in the subcutis of rabbits for periods up to 2 years. After 2 years, only traces of microscopic cracks were seen on half the PS-35 samples, PS-20 significantly delayed MIO, while the polysiloxane-free control was very severely degraded. Infrared spectroscopy established that polyether soft segment oxidation was occurring in PS-20. We could not directly evaluate oxidation in PS-35 because siloxane bands mask the aliphatic ether. Indirect FTIR evidence suggests that there is very slight polyether oxidation that develops early, and then seems to stabilize. The molecular weight of degraded PS-20 decreased. That of microcracked PS-35 decreased negligibly while that of undamaged PS-35 increased slightly after 2-year in vivo. The polysiloxane-free control was profoundly degraded. PS-20 has much improved MIO resistance, while that for PS-35 is highly MIO resistant compared with its polysiloxane-free control.

Animals↗
PubMed2006

Late effects in 164 patients with rhabdomyosarcoma of the bladder/prostate region: a report from the international workshop.

PURPOSE: We determined the late sequelae in children and adolescents with rhabdomyosarcoma of the bladder/prostate treated in the United States, Canada and selected Western European countries, primarily France, Germany, Italy and the United Kingdom, from 1979 to 1998. MATERIALS AND METHODS: We used a data collection form to record data from patient records available at the group statistical centers. RESULTS: A total of 164 patient charts had sufficient data available to be included in the study. Median patient age at diagnosis was 2.4 years. Median length of followup was approximately 8 years (range 3 to 24). Of the patients with available data 78 did not undergo cystectomy, 49 underwent partial cystectomy and 34 underwent complete cystectomy. Urinary continence was assessed at age 6 years or older in 62 patients who did not undergo cystectomy. Of these patients 43 (69%) were continent, 16 had nocturnal incontinence and 9 had diurnal incontinence. Of 44 patients who underwent partial cystectomy and had pertinent followup data 32 (73%) were continent, and 12 had nocturnal and/or diurnal incontinence. Only 11 patients underwent urodynamic investigation. Other nephrourological complications consisted of 3 or more urinary tract infections in 29 of 53 patients, abnormal renal function in 19 of 48 (tubulopathy 14, increased creatinine/blood urea nitrogen 5), chronic hematuria in 13 of 51 and hydronephrosis in 8 of 54 with available data. Vesicoureteral reflux, urinary stones and bowel problems were infrequent. CONCLUSIONS: Of the patients 48% had a relatively intact bladder after biopsy only. However, 31% of patients 6 years or older had some urinary incontinence, as did 27% of patients who had undergone partial cystectomy. In addition, 55% of all patients had 3 or more urinary tract infections, 40% had decreased renal function and 25% had chronic hematuria. Other complications were present in 15% or less of the patients with available data.

Adolescent↗
PubMed2006

Determination of 238u/235u, 236u/238u and uranium concentration in urine using sf-icp-ms and mc-icp-ms: an interlaboratory comparison.

Accidental exposure to depleted or enriched uranium may occur in a variety of circumstances. There is a need to quantify such exposure, with the possibility that the testing may post-date exposure by months or years. Therefore, it is important to develop a very sensitive test to measure precisely the isotopic composition of uranium in urine at low levels of concentration. The results of an interlaboratory comparison using sector field (SF)-inductively coupled plasma-mass spectrometry (ICP-MS) and multiple collector (MC)-ICP-MS for the measurement of uranium concentration and U/U and U/U isotopic ratios of human urine samples are presented. Three urine samples were verified to contain uranium at 1-5 ng L and shown to have natural uranium isotopic composition. Portions of these urine batches were doped with depleted uranium (DU) containing small quantities of U, and the solutions were split into 100 mL and 400 mL aliquots that were subsequently measured blind by three laboratories. All methods investigated were able to measure accurately U/U with precisions of approximately 0.5% to approximately 4%, but only selected MC-ICP-MS methods were capable of consistently analyzing U/U to reasonable precision at the approximately 20 fg L level of U abundance. Isotope dilution using a U tracer demonstrates the ability to measure concentrations to better than +/-4% with the MC-ICP-MS method, though sample heterogeneity in urine samples was shown to be problematic in some cases. MC-ICP-MS outperformed SF-ICP-MS methods, as was expected. The MC-ICP-MS methodology described is capable of measuring to approximately 1% precision the U/U of any sample of human urine over the entire range of uranium abundance down to <1 ng L, and detecting very small amounts of DU contained therein.

Humans↗
PubMed2006

Expression of retinoid receptors in sebaceous cell carcinoma.

PURPOSE: The aim of this study is to investigate whether there are any abnormalities in the in vivo expression of retinoid acid receptors (RAR-alpha, RAR-beta and RAR-gamma) and retinoid X receptors (RXR-alpha, RXR-beta and RXR-gamma) in sebaceous cell carcinoma. METHODS: Expression of retinoid receptors in paired specimens of cancerous tissues (n = 10) and adjacent normal tissues (n = 10) from 10 patients with sebaceous cell carcinoma was studied immunohistochemically by using anti-retinoid receptor antibodies. RESULTS: In eight of the 10 normal tissue samples, all six receptors were expressed. In the other two samples, all receptors were expressed except RAR-gamma (one sample) or RXR-gamma (two samples). Five tumours (50%) lacked RAR-alpha; RAR-alpha expression was lower in tumours than in normal tissues in eight of 10 cases. RAR-beta was expressed in the cytoplasm of nine of 10 tumours; RAR-beta expression was at least as high in tumours as in normal tissue in eight of 10 cases. Two tumours lacked RAR-gamma; three tumours had lower RAR-gamma expression than paired normal epithelium; four had the same RAR-gamma expression, and one had higher RAR-gamma expression. RXR-alpha expression was strong in all normal tissues and tumour samples. Ten tumours lacked RXR-beta and all 10 tumours lacked RXR-gamma expression. CONCLUSIONS: Diminished RXR-beta and RXR-gamma expression might be related to the development of sebaceous cell carcinoma. Additional studies are required to establish whether the defects in RAR expression in sebaceous cell carcinoma might affect the potential response of this tumour to treatment with retinoids.

Adenocarcinoma, Sebaceous↗
PubMed2006

Reliability and reproducibility of dens fracture classification with use of plain radiography and reformatted computer-aided tomography.

BACKGROUND: The classification system of dens fractures by Anderson and D'Alonzo has been widely used in clinical studies. Of the three types of fractures, Type II and Type III are of particular importance because the distinction between them may affect treatment decisions. The purposes of this study were to assess whether this classification is reliable and reproducible and to determine whether computed tomography can improve its reliability and reproducibility. METHODS: Plain radiographs and spiral computed tomography images of dens fractures in eleven patients were assessed, and the fractures were assigned a classification of Type II or Type III at two readings, separated by six months, by two spine surgeons and three neuroradiologists. Kappa coefficients of agreement between the raters as well as the reproducibility of the classifications made by the individual raters were calculated independently for the fracture classifications based on the plain radiographs and those based on the reformatted computed tomography scans. RESULTS: The kappa coefficient for classifications based on plain radiographs was 0.30 and 0.25 (fair agreement) at the first and second readings, respectively. For classifications based on computed tomography scans, the corresponding kappa coefficients were 0.46 (moderate agreement) and 0.67 (substantial agreement). The kappa coefficients for intrarater reliability among the five raters averaged 0.56 (moderate agreement) when computed tomography scans were used and 0.28 (fair agreement) when plain radiographs were used. CONCLUSIONS: Substantial variation with regard to the classification of dens fractures was found within our group of raters. Greater agreement occurred when reformatted computed tomography scans rather than plain radiographs were used as the basis for classification. When classifying dens fractures according to the system of Anderson and D'Alonzo, one should consider using reformatted computed tomography scans and reaching a consensus with multiple raters.

Adolescent↗
PubMed2006

Surgical modifications in bladder neck reconstruction and vesicourethral anastomosis during radical retropubic prostatectomy to reduce bladder neck contractures.

PURPOSE: We describe surgical modifications in radical retropubic prostatectomy (RRP) which have significantly reduced the incidence of bladder neck contractures (BNC). MATERIALS AND METHODS: Between March 1994-July 2005, 977 men underwent a RRP by a single surgeon. Group I comprised 548 patients operated upon July 1994-December 1999, without the modifications described below. Group II comprised 429 men operated upon January 2000-December 2004, with the following surgical modifications: 1) reconstruction of the bladder neck (BN) to a diameter of 28 French; 2) placement of the posterior (6 o'clock) vesicourethral suture on mild traction before placing this suture into the bladder, allowing inspection and, if necessary, replacement of any of the previously placed sutures; 3) bladder displacement when tying the vesicourethral sutures which allows the sutures to be tied under direct vision and prevents incorporation of extraneous tissue. Data were retrospectively analyzed. RESULTS: Demographic data were comparable between groups. In group I, 31/548 (5.7%) developed a BNC compared to 1/429 (0.2%) in Group II, p < 0.001. Urinary continence (no pads/maximum of one light pad for security in 24 hours) at 12 months in the 32 patients who developed a BNC was worse when compared to patients who did not develop a BNC (58% versus 80%, p = 0.003). After excluding the patients who developed a BNC, continence rates were comparable between both groups. The positive margin rate at the BN was not adversely affected by these modifications. CONCLUSIONS: Simple, easily applied modifications to the management of the BN and vesicourethral anastomosis can substantially reduce the incidence of BNC.

Adenocarcinoma↗
PubMed2005

In vivo biostability of polyether polyurethanes with polyethylene oxide surface-modifying end groups; resistance to biologic oxidation and stress cracking.

Polyethylene oxide (PEO) on polymer surfaces has been reported to reduce cellular adhesion, a very desirable property for cardiac pacing leads. A Shore 80A polyether polyurethane with up to 6% PEO surface-modifying end groups (SME) was evaluated for its chronic in vivo biostability. In a short-term (12 week) screening test, strained samples appeared to develop the same surface oxidation as unmodified polymer, but did not produce visible cracking > or =500x, prompting a longer-term study. By the time the longer-term study was initiated, most of the PEO SME had disappeared from the starting material's surface. After 1 year in vivo, surface oxidation, shallow surface cracking, and environmental stress cracking (ESC) developed on highly strained samples to the point of failure, so that there was no significant difference between the SME polymer and its control (the same polymer without SME). No further change was seen for up to 2 years of implantation. Unstrained PEO SME polymer developed shallow surface cracking, but no ESC up to 2 years of implantation. Thus, PEO SME slightly delayed, but did not stop biodegradation, and under unstrained conditions, has no adverse effect on biostability.

Absorbable Implants↗
PubMed2005

Total leukocyte control for elective coronary bypass surgery does not improve short-term outcome.

BACKGROUND: Despite early promise as a means of reducing the inflammatory response to surgery and subsequent organ damage, the evidence of the clinical value of leukocyte filtration remains equivocal. METHODS: Three hundred patients presenting for routine coronary artery bypass surgery were randomized to a total leukocyte filtration group (filters in five different locations) and a control group with a standard 40-mum filter in the bypass return line only. Data on efficacy and safety of leukocyte filtration were collected by research and postoperative care staff who were blinded to the mode of filtration. RESULTS: Leukofiltration achieved a transient fall in white cells immediately after surgery (p = 0.07) and a sustained fall in platelets, which was still significant on the second postoperative day (p = 0.0001). However, there were no significant differences in postoperative hospital stay, the primary outcome variable (p = 0.35), in ICU stay (p = 0.92), or mortality (p = 1.0). There were no differences in postoperative cardiac status including cardiac output (p = 0.16), inotrope (p = 0.93) or balloon pump (p = 0.48) requirement, or 24-hour troponin (p = 0.60). Similarly there were no differences in pulmonary or renal function (intubation time (p = 0.83), respiratory index (p = 0.19) rise in creatinine (p = 0.13) or hemofiltration (1.0)). Leukofitration was not associated with a statistically significant increase in bleeding or requirement for blood or blood products. It was associated with a decrease approaching significance (p = 0.1) in number and severity of postoperative wound infections. Three filters were blocked during use but were changed without incident or compromise to patient safety. CONCLUSIONS: Leukocyte filtration is safe but not efficacious in improving short-term outcome.

Aged↗
PubMed2005

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Air Pollutants↗
PubMed2005

Relationship quality, coital frequency, and condom use as predictors of incident genital Chlamydia trachomatis infection among adolescent women.

PURPOSE: To explore associations of relationship quality, coital frequency, unprotected coitus, and chlamydia infection over time. METHODS: Data came from 142 adolescent females with sexually transmitted infections attending three primary care adolescent clinics and one county STD clinic. Interview data were collected at 3 time points: enrollment, 1 month, and 3 months after enrollment. Predictor variables included relationship quality, coital frequency, unprotected coitus, and partner change. The outcome variable was infection with C. trachomatis at 3 months. Analyses were conducted using structural equation modeling. RESULTS: Chlamydia infection at 3 months was directly influenced by unprotected coitus during the previous 2 months (Beta = .25; p < or = .05) and partner change during the enrollment/1-month interval. Unprotected coitus was directly associated with coital frequency, both cross-sectionally and longitudinally. Increased relationship quality was associated with increased coital frequency but did not have direct effects on unprotected coitus. CONCLUSIONS: The data showed a protective effect of condom use for chlamydia infections. Prevention efforts should attend to the interpersonal factors behind decisions to use or not use condoms.

Adolescent↗