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Biomedical subjects

Stephen Connor

Publications and source records attributed to Stephen Connor.

12 recordsLinked to original sources
PubMed2006

A novel approach to brachytherapy in hepatocellular carcinoma using a phosphorous32 (32P) brachytherapy delivery device--a first-in-man study.

PURPOSE: While potentially very useful, percutaneously delivered brachytherapy of inoperable intra-abdominal solid tumors faces significant technical challenges. This first-in-man study is designed to determine the safety profile and therapeutic efficacy of a novel phosphorous (32P) brachytherapy device (BrachySil) in patients with unresectable hepatocellular carcinoma. METHODS AND MATERIALS: Patients received single percutaneous and transperitoneal implantations of BrachySil under local anesthesia directly into liver tumors under ultrasound or computed tomographic guidance, at an activity level of 4 MBq/cc of tumor. Toxicity was assessed by the nature, incidence, and severity of adverse events (Common Toxicity Criteria scores) and by hematology and clinical chemistry parameters. Target tumor response was assessed with computed tomographic scans at 12 and 24 weeks postimplantation using World Health Organization criteria. RESULTS: Implantations were successfully carried out in 8 patients (13-74 MBq, mean 40 MBq per tumor) awake and under local anesthesia. Six of the 8 patients reported 19 adverse events, but no serious events were attributable to the study device. Changes in hematology and clinical chemistry were similarly minimal and reflected progressive underlying hepatic disease. All targeted tumors were responding at 12 weeks, with complete response (100% regression) in three lesions. At the end of the study, there were two complete responses, two partial responses, three stable diseases, and one progressive disease. CONCLUSION: Percutaneous implantation of this novel 32P brachytherapy device into hepatocellular carcinoma is safe and well tolerated. A significant degree of antitumor efficacy was demonstrated at this low dose that warrants further investigation.

Aged↗
PubMed2006

Opioid use and survival at the end of life: a survey of a hospice population.

Concern that opioids hasten death may be among the reasons that pain is treated inadequately in populations with advanced illness. Studies that assess the true risks are needed. To determine whether survival after last opioid dose change is associated with opioid dosing characteristics and other factors, data from the National Hospice Outcomes Project, a large prospective cohort study involving 13 U.S. hospice programs, were analyzed. Of 1,306 patients, 725 received opioids and underwent at least one dose change before death. Subsamples based on maximum opioid dose compared patients receiving usual doses with those receiving high-dose therapy. Spearman rank correlations examined bivariate associations between survival after final dose change and other variables, including dose in morphine equivalent mg and percentage dose increase. Multivariate least squares regression analyses determined associations between survival and other variables, including those significant in bivariate analyses. The mean+/-SD number of days between final dose change and death was 12.46+/-23.11. Multivariate models demonstrated a significant association between shorter survival and higher opioid dose, a cancer diagnosis, unresponsiveness, and pain of <5 on a 0-10 scale, but none of these models explained >10% of the variance in time till death. Analyses of subsamples did not reveal additional effects of dose. This analysis revealed that opioid dosing was associated with time till death, but this factor would explain very little of the variation in survival. In a hospice population, survival is influenced by complex factors, many of which may not be measurable. Based on these findings, concern about hastening death does not justify withholding opioid therapy.

Aged↗
PubMed2006

A general method for assembling single colloidal particle lines.

We have developed a general method for assembling colloidal particles into one-dimensional lines of single particle thickness. Well-spaced, parallel single particle lines can be readily deposited on a substrate from a dilute Langmuir-Blodgett particle monolayer via a stick-slip motion of the water-substrate contact line. The particle density within the lines is controllable by the particle concentration in the monolayer as well as the pulling speed of the substrate. Lines of a great variety of materials and sizes, ranging from a few nanometers to a few micrometers, have been demonstrated. Multiple depositions create complex patterns such as cross lines, even of different particles. The ability of placing nanoparticles into one-dimensional arrays enables the construction of higher hierarchical device structures. For example, using gold nanoparticle seeds, vertical single nanowire arrays of silicon can be grown replicating the pattern of single particle lines.

Journal Article↗
PubMed2006

Haemorrhagic acute disseminated encephalomyelitis: an unusual case of blindness in an HIV-infected patient.

Acute disseminated encephalomyelitis (ADEM) is a monophasic, polysymptomatic, immune-mediated demyelinating disorder involving central nervous system (CNS) white matter. It is usually seen in association with exanthematous viral illnesses, systemic infections or vaccinations. The haemorrhagic form of ADEM is rarer and follows a more fulminant course. We describe a case of haemorrhagic ADEM in an HIV-infected patient presenting solely with acute onset bilateral blindness and normal retina. ADEM was diagnosed from clinical, laboratory and radiological findings. Although ADEM has been seen with HIV seroconversion illness and in chronic infection, the haemorrhagic form has never been reported in association with HIV. Acute onset blindness is extremely rare in HIV-positive patients. A Medline search revealed very few reports. The importance of considering haemorrhagic ADEM as aetiology of blindness in such a scenario is discussed.

Adult↗
PubMed2005

Organic pollutants in wild ducks from New York state: I. Interspecies differences in concentrations and congener profiles of PCBs and PCDDs/PCDFs.

Wild ducks of three species, common mergansers (Mergus merganser americanus), gadwalls (Anas streptera), and mallards (Anas platyrhynchos), were collected near industrial sites in the Massena, NY area of the St. Lawrence River (SLR) in 1988/89 and 1994. Additional samples were collected in 1994 near a former polychlorinated biphenyl (PCB) capacitor plant at Fort Edward, NY (a mallard and two wood ducks (Aix sponsa)), and at control sites (common mergansers, mallards and wood ducks). On a lipid basis, PCB concentrations in liver tissue from the 1994 collection ranged from 0.1 mug/g in a control wood duck to 676 mug/g in a common merganser from the SLR area. However, the highest total polychlorinated dibenzofuran (PCDF) concentrations were found in liver and fat tissues of gadwalls and mallards collected near the SLR industrial sites (2.8-12 ng/g lipid). These two species bioaccumulated non-2,3,7,8-substituted PCDFs in addition to 2,3,7,8-PCDF isomers, whereas common mergansers preferentially bioaccumulated 2,3,7,8-substituted PCDFs. The mergansers from the SLR sites were the only specimens contaminated with polychlorinated dibenzo-p-dioxins (PCDDs), which were all 2,3,7,8-substituted. The PCB and PCDF congener patterns in the duck tissues appear to have been influenced by both sampling location and species trophic level.

Adipose Tissue↗
PubMed2005

Spontaneous formation of nanoparticle stripe patterns through dewetting.

Significant advancement has been made in nanoparticle research, with synthetic techniques extending over a wide range of materials with good control over particle size and shape. A grand challenge is assembling and positioning the nanoparticles in desired locations to construct complex, higher-order functional structures. Controlled positioning of nanoparticles has been achieved in pre-defined templates fabricated by top-down approaches. A self-assembly method, however, is highly desirable because of its simplicity and compatibility with heterogeneous integration processes. Here we report on the spontaneous formation of ordered gold and silver nanoparticle stripe patterns on dewetting a dilute film of polymer-coated nanoparticles floating on a water surface. Well-aligned stripe patterns with tunable orientation, thickness and periodicity at the micrometre scale were obtained by transferring nanoparticles from a floating film onto a substrate in a dip-coating fashion. This facile technique opens up a new avenue for lithography-free patterning of nanoparticle arrays for various applications including, for example, multiplexed surface-enhanced Raman substrates and templated fabrication of higher-order nanostructures.

Gold↗
PubMed2005

Pt nanocrystals: shape control and Langmuir-Blodgett monolayer formation.

We report the synthesis of monodisperse Pt nanocrystals with three different shapes-cubes, cuboctahedra, and octahedra, selectively, with similar sizes of 9-10 nm by a modified polyol process. We found that addition of silver ion enhances the crystal growth rate along 100, and essentially determines the shape and surface structure of the Pt nanocrystals. After the reaction, the silver species can be easily removed by repetitive precipitation giving pure Pt nanoparticles. Two-dimensional arrays of the Pt nanocrystals were assembled by using the Langmuir-Blodgett (LB) method. The particles were evenly distributed on the entire substrate, and their surface coverage and density can be precisely controlled by tuning the surface pressure. The resulting Pt LB layers are potential candidates for 2-D model catalysts as a result of their high surface area and the structural uniformity of the metal nanocrystals.

Crystallization↗
PubMed2004

Survey on use of palliative radiotherapy in hospice care.

PURPOSE: Radiation oncologists and hospice professionals both provide end-of-life care for oncology patients, and little has been written about the interface between these two groups of specialists. Hospice professionals were surveyed to assess the perceived need for palliative radiotherapy in the hospice setting, to investigate factors that limit the access of hospice patients to radiotherapy, and to suggest areas of future collaboration on education, research, and patient advocacy. PATIENTS AND METHODS: Members of the National Hospice and Palliative Care Organization (NHPCO) and American Society for Therapeutic Radiology and Oncology jointly authored a questionnaire to investigate the beliefs of hospice professionals toward the use of radiotherapy for oncology patients in hospice. The questionnaire was distributed to all NHPCO member institutions, and the results were compiled and statistically analyzed. RESULTS: Four hundred eighty of more than 1,800 surveyed facilities responded to the questionnaire. The findings suggest that the majority of hospice professionals feel that radiotherapy is important in palliative oncology and that radiotherapy is widely available in the United States. Yet less than 3% on average of hospice patients served by hospices responding to the survey actually received radiotherapy in 2002. The most common barriers to radiotherapy in hospice care include radiotherapy expense, transportation difficulties, short life expectancy, and educational deficiencies between the specialties. CONCLUSION: Multiple barriers act to limit the use of palliative radiotherapy in hospice care. Finding ways to surmount these obstacles will provide opportunity for improvement in the end-of-life care of cancer patients.

Attitude of Health Personnel↗
PubMed2004

Medicare cost in matched hospice and non-hospice cohorts.

Hospice care is perceived as enhancing life quality for patients with advanced, incurable illness, but cost comparisons to non-hospice patients are difficult to make. The very large Medicare expenditures for care given during the end of life, combined with the pressure on Medicare spending, make this information important. We sought to identify cost differences between patients who do and do not elect to receive Medicare-paid hospice benefits. We introduce an innovative prospective/retrospective case-control method that we used to study 8,700 patients from a sample of 5% of the entire Medicare beneficiary population for 1999-2000 associated with 16 narrowly defined indicative markers. For the majority of cohorts, mean and median Medicare costs were lower for patients enrolled in hospice care. The lower costs were not associated with shorter duration until death. For important terminal medical conditions, including non-cancers, costs are lower for patients receiving hospice care. The lower cost is not associated with shorter time until death, and appears to be associated with longer mean time until death.

Aged↗