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Biomedical subjects

A Meek

Publications and source records attributed to A Meek.

15 recordsLinked to original sources
PubMed2005

Treatment and management of challenging behaviours in congregate and noncongregate community-based supported accommodation.

OBJECTIVES: To compare the nature and prevalence of use of procedures employed to treat and manage challenging behaviours across two approaches to providing community-based supported accommodation for people with intellectual disabilities (ID) and severe challenging behaviour: noncongregate settings where the minority of residents have challenging behaviour, and congregate settings where the majority of residents have challenging behaviour. SETTING: Community-based supported accommodation for people with ID and challenging behaviour. DESIGN: Longitudinal matched groups design. MAIN OUTCOME MEASURES: The nature and prevalence of use of procedures employed to treat and manage challenging behaviours. Observed and reported severity of challenging behaviours. RESULTS: Both types of settings were associated with low prevalence of use of behavioural technologies for the reduction of challenging behaviour (less than 15% of participants). In contrast, high proportions of participant received antipsychotic medication in both noncongregate (56%) and congregate (80%) settings. Congregate settings were associated with the increased use of physical restraint as a reactive management strategy, with over half of participants being in receipt of physical restraint by two or more members of staff. DISCUSSION: Changes in reported and observed challenging behaviour over a 10-month period were slight. The use of evidence-based behavioural technologies for the reduction of challenging behaviour may have led to better outcomes.

Adult↗
PubMed2001

Hatchery-level predictive values for infectious pancreatic necrosis virus and Aeromonas salmonicida in Ontario, Canada.

The probability and uncertainty of correctly classifying the IPNV and Aeromonas salmonicida status of fish-rearing and natural sites in Ontario were estimated through Monte Carlo simulations. Propagating several uncertain inputs showed the extent to which natural variability and our present lack of knowledge affect the probability of site misclassification. For the scenarios investigated, the site-level negative predictive values (SNPVs) were high and fairly constant. The site-level positive predictive values (SPPVs) - given a test specificity ranging between 0.999 and 1.0 - were much lower, more variable, and highly affected by cut-off point and sample size. Substantial uncertainty resides in classifying the pathogen status of test-positive sites, whereas much less uncertainty resides in classifying pathogen status of test-negative sites.

Aeromonas↗
PubMed2000

Therapy for patients with high grade astrocytoma using intraarterial chemotherapy and radiation therapy.

BACKGROUND: High grade astrocytomas account for approximately 40% of all primary brain tumors. The median survival is approximately 8-10 months for patients with glioblastoma multiforme and 36 months for patients with anaplastic astrocytoma. The results of systemic chemotherapy in the treatment of brain tumors have been reported to be less than satisfactory, mainly because of the blood-brain barrier impermeability for chemotherapeutic drugs. Intraarterial chemotherapy has been an attractive alternative with which to overcome this problem. METHODS: Eighty-three patients with high grade astrocytoma (glioblastoma multiforme [63 patients] and anaplastic astrocytoma--[20 patients]) were treated with intraarterial (intracarotid and/or intravertebral) chemotherapy and radiation therapy between 1987 and 1997. Patients received cisplatin, 60 mg/m2, and etoposide, 40 mg/m2. Radiation therapy was delivered either after completion of the chemotherapy or concomitantly with the chemotherapy. RESULTS: Thirty-four of 71 evaluable patients with high grade astrocytoma (48%) responded to the chemotherapy. The median survival for patients with glioblastoma multiforme who received chemotherapy prior to radiation therapy was 20 months versus 7 months for those patients who underwent concomitant chemotherapy/radiation therapy. Patients with anaplastic astrocytoma who received chemotherapy prior to radiation therapy had a median survival of 45 months compared with 12 months for patients who received concomitant chemotherapy/ radiation therapy. The toxicity profile has been reported to be mild and well tolerated. CONCLUSIONS: Intraarterial chemotherapy for patients with glioblastoma multiforme, delivered prior to radiation therapy, appears to result in a median survival three times longer than that achieved with concomitant chemotherapy/radiation therapy. In addition, patients appear to survive substantially longer than they do after radiation therapy with the addition of systemic chemotherapy. Side effects are reported to be acceptable.

Adult↗
PubMed1999

Toxicities related to intraarterial infusion of cisplatin and etoposide in patients with brain tumors.

Chemotherapy for malignant brain tumors has a limited efficacy largely due to restricted blood-brain barrier permeability for chemotherapeutic drugs. Intraarterial chemotherapy (IAC) has the advantage of increased uptake during the first passage of the drugs through tumor capillaries. Initial IAC trials had less than satisfactory results due to unacceptable toxicities. Between 1987 and 1996, 173 patients with primary and metastatic brain tumors were treated with intraarterial (intracarotid and/or intravertebral) cisplatin and etoposide (VP-16). Out of these, 168 patients, who received a total of 438 cycles, were evaluated for the incidence of toxicities. Patients received either cisplatin at 40 mg/m2 and VP-16 at 20 mg/m2 or cisplatin at 60 mg/m2 and VP-16 at 40 mg/m2. Nausea and vomiting were the most common toxicities (42 patients, 14% of cycles). Arterial puncture was associated with a 1.6% incidence of groin hematomas (6 patients), and a 0.7% incidence of failure to canulate the carotid or vertebral arteries (3 patients). Neurologic toxicities included headache (1.4% of cycles, 5 patients), focal seizures (1.4% of cycles, 5 patients), transient confusion and urinary retention/incontinence (1.9% of cycles, 8 patients), and blurred vision (0.9% of cycles, 4 patients). We have not seen visual loss, strokes, major vessel dissection or thrombosis, or myelosuppression. Toxicity incidence was higher in patients with metastatic brain tumors than in those with primary brain tumors (34% versus 17%, p < 0.001). It was also higher in patients who had brain radiation therapy (RT) prior to IAC than in those who had RT concomitant with IAC (31% versus 19%, p = 0.05). No significant difference in toxicity incidence was noticed between patients who received RT concomitant with IAC and those who received RT after IAC (19% and 23% respectively, p = 0.08). Intracarotid chemotherapy given prior to RT resulted in 23 months of median survival for patients with glioblastoma multiforme. Intraarterial chemotherapy with cisplatin and VP-16 is a relatively safe treatment modality, especially in patients with primary brain tumors who have not received brain radiotherapy.

Adolescent↗
PubMed1991

Intracarotid chemotherapy with etoposide and cisplatin for malignant brain tumors.

Chemotherapy for tumors of the central nervous system has a limited efficacy presumably because of restricted blood-brain barrier permeability. The advantage of regional intra-arterial administration of anticancer drugs is an increased uptake during the first passage of the drugs through tumor capillaries. Twenty patients with high-grade astrocytomas (HGA) and 28 patients with metastatic brain tumors (MBT) received intracarotid/intravertebral infusion of etoposide and cisplatin. Eight patients with HGA who underwent incomplete resection responded to chemotherapy alone. Four additional patients had complete resection of the tumor. Median survival time of the group (responders and nonresponders) has been 14 months. Twelve patients with MBT responded to chemotherapy alone (six had complete response [CR], and six had partial response [PR]) with a median survival time of 7 months. Intra-arterial chemotherapy (IAC) appears to be effective with acceptable toxicities. Accrual of additional patients is required before a final conclusion can be reached.

Adult↗
PubMed1990

Analysis of 5-iodo-2'-deoxyuridine incorporation in murine melanoma for photon activation therapy.

Quantitative evaluation of the dose enhancement obtained with analog nucleoside agents such as iododeoxyuridine (IdUrd) requires knowledge of the degree to which the thymidine (Thd) in DNA is replaced by IdUrd. In the present investigation, mice were infused with IdUrd using an intravenous infusion apparatus capable of delivering continuous multi-day infusions without restraining the mice. The absolute incorporation of IdUrd in DNA was measured by 125IdUrd label, both in whole tissue and extracted DNA, showing a good correlation between levels observed in DNA and whole tissue. Replacement in a Harding-Passey murine melanoma tumor carried in BALB/c mice approached 10%. In addition, a Neutron Activation Analysis (NAA) technique was developed which showed in vitro, a sensitivity sufficient to evaluate the % replacement of Thd by IdUrd in small biological samples with a sensitivity greater than 0.1 ppm, at 1% replacement in mg samples. This method can provide information on iodine substitution in DNA in humans where the use of a radioactive DNA-seeking substance would be undesirable. Analyses of IdUrd incorporation in cultured cells by NAA and 125I counting showed good agreement.

Animals↗
PubMed1988

Synergistic effects of combined immunosuppressive modulation. I. Unresponsiveness to dendritic cell-depleted renal allografts in dogs exposed to total-lymphoid irradiation.

Attenuation of the allogeneic stimulus provided by dendritic cells (DC) was achieved by irradiation of the donors, followed by their reconstitution with bone marrow from the prospective DLA-identical recipient. Following long-term (131-187 days) recovery free of graft-versus-host (GVH) disease, the chimeric kidneys were placed into the corresponding recipients; such allografts were rejected at 55, 55, and 60 days, respectively. Four other recipients were conditioned with 1750-1790 cgy of total lymphoid irradiation (TLI) and were then given a similar chimeric kidney from the corresponding partner. These allografts currently survive for 296, 295, 290, and 252 days, respectively. A third group of four dogs was exposed to TLI prior to transplantation of a normal DLA-identical kidney. These grafts were rejected at 20, 42, 46, and 242 days, respectively. Thirteen DLA-identical renal allografts transplanted into normal dogs survived for 13-38 days (mean survival time = 28.6 days). Depletion of allogeneic DC alone, or TLI alone, produced relative prolongations in allograft survival in canine recipients. Combined use of these two modalities, however, resulted in long-term allogeneic unresponsiveness in the recipients.

Animals↗
PubMedDate not supplied

Video techniques for on-line portal imaging.

The application of on-line portal imaging techniques to the verification of treatment precision is reviewed. The design parameters for a video portal imaging system are described, and the optimization of image quality is discussed with particular emphasis on photon noise. On-line images are presented for a head phantom imaged on a 4 MV linac, and compared with a conventional portal film. The relative advantages of an on-line system are compared with conventional portal film analysis.

Humans↗
PubMedDate not supplied

Dose enhancement in buildup region by lead, aluminum, and lucite absorbers for 15 MVp photon beam.

Changes in dose distributions in buildup region resulting from the presence of lead, aluminum, and lucite absorbers above the surface of a polystyrene phantom were evaluated. The surface dose, as a function of the absorber thickness, is presented as well as the influence of the air gap between the lead absorber and the phantom surface. It has been found that the surface dose does not depend on absorber thickness for absorbers thicker than the range of secondary electrons in the absorber material (after corrections for the attenuation of the primary beam in the absorber). Similarly, the depth dose curves in the phantom were elevated only at depths lower than the range of secondary electrons in the phantom. The applicability of the presented data in clinical radiotherapy is discussed.

Absorption↗