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Biomedical subjects

A York

Publications and source records attributed to A York.

At least 19 recordsLinked to original sources
PubMed2001

Fluorescence anisotropy: a method for early detection of Alzheimer beta-peptide (Abeta) aggregation.

Time-resolved anisotropy measurements (TRAMS) have been used to study the aggregation of the beta-amyloid (Abeta) peptide which is suspected of playing a central role in the pathogenesis of Alzheimer's Disease (AD). The experiments, which employ small quantities of fluorescently-labelled Abeta, in addition to the untagged peptide, have shown that the sensitive TRAMS technique detects the presence of preformed "seed" particles in freshly prepared solutions of Abeta. More importantly, as 100 microM solutions of Abeta containing tagged Abeta at a concentration level of either 0.5 or 1 microM are incubated, the TRAMS prove capable of detection of the peptide aggregation process through the appearance of a continuously increasing "residual anisotropy" within the time-resolved fluorescence data. The method detects Abeta aggregation in its earliest stages, well before complexation becomes apparent in more conventional methods such as the thioflavin T fluorescence assay. The TRAMS approach promises to provide a most attractive route for establishment of a high-throughput procedure for the early detection of the presence of amyloid aggregates in the screening of biological samples.

Alzheimer Disease↗
PubMed2001

Modulation of beta-amyloid production and fibrillization.

Alzheimer's disease (AD) is the most common cause of dementia in old age and presently affects an estimated 4 million people in the U.S.A. and 0.75 million people in the U.K. It is a relentless, degenerative brain disease, characterized by progressive cognitive impairment. In the final stages of the disease, patients are often bedridden, doubly incontinent and unable to speak or to recognize close relatives. Pathological changes of Alzheimer's disease include extensive neuronal loss and the presence of numerous neurofibrillary tangles and senile plaques in the brain. The senile plaques contain amyloid fibrils derived from a 39-43-amino-acid peptide referred to as beta-amyloid or A beta. The basic theory of the so-called 'amyloid hypothesis' is that the deposition of aggregated forms of A beta in the brain parenchyma triggers a pathological cascade of events that leads to neurofibrillary tangle formation, neuronal loss and the associated dementia [1]. Here we discuss progress towards the identification of inhibitors of A beta production and fibrillization.

Alzheimer Disease↗
PubMed2001

The clinical and biological effects of thalidomide in patients with myelodysplastic syndromes.

Thirty patients with myelodysplastic syndromes (MDS) were treated with thalidomide at 100 mg/d p.o., increased as tolerated to 400 mg/d for 12 weeks. Levels of apoptosis, macrophage number, microvessel density (MVD), tumour necrosis factor alpha (TNF-alpha), transforming growth factor beta (TGF-beta), interleukin 6 (IL-6), vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were determined in the serum, bone marrow (BM) plasma and BM biopsies before and after therapy. Pretherapy biological characteristics of MDS patients were compared with similar studies performed in 11 normal volunteers. Ten patients demonstrated haematological improvement in the erythroid series, six becoming transfusion independent. Responders had a higher pretherapy platelet count (P < 0.048) and lower BM blasts (P < 0.013). Median time to response was 10 weeks, and four remain in remission beyond a year. Pretherapy MDS BMs showed higher MVD (P < 0.001) and TGF-beta (P < 0.03) and higher serum TNF-alpha (P < 0.008) compared with normal control subjects. After therapy, only BM TGF-beta decreased significantly (P < 0.002). Pretherapy haemoglobin was directly related to serum VEGF (P < 0.001) in responders and inversely related in non-responders (P < 0.05), suggesting the possibility that angiogenesis may be a primary pathology in the former and a consequence of anaemia-induced hypoxia in the latter. We conclude that thalidomide has important clinical and biological effects in at least a subset of MDS patients, but the precise mechanism of its action remains unknown and requires further study including a larger number of patients.

Aged↗
PubMed1999

Non-specific effect of naltrexone on ethanol consumption in social drinkers.

RATIONALE: Clinical studies have shown that the opioid antagonist naltrexone is effective in the treatment of alcoholism. However, the mechanism by which it produces this effect is not understood. OBJECTIVE: This study was designed to investigate the effect of acute naltrexone on consumption of ethanol in healthy, non-problem social drinkers. METHODS: Subjects (n=24) participated in an eight-session, within-subject, placebo-controlled choice procedure which measured ethanol preference and consumption. The procedure consisted of two blocks of four sessions in which subjects received either naltrexone (50 mg oral) or placebo 1 h before consuming an ethanol or placebo beverage. On the first two sessions of each block, subjects received a color-coded beverage containing ethanol (0.75 g/kg) or placebo, in five equal portions at 15-min intervals. On the next two sessions of each block, subjects chose which beverage they preferred (i.e., placebo or ethanol) and how much they wished to take, in unit doses (placebo or ethanol 0.15 g/kg/dose). The primary behavioral measures were (1) the number of times subjects chose ethanol over placebo, and (2) the number of doses they consumed. Subjects rated their mood states and subjective drug effects at regular intervals during each session. RESULTS: Naltrexone did not alter the frequency of ethanol (versus placebo) choice. Although naltrexone did decrease the total number of ethanol doses subjects took (mean 2.7 doses after naltrexone; 3.4 doses after placebo), it also decreased the number of placebo "doses" subjects took on sessions when they chose the placebo beverage (mean 1.6 placebo doses after naltrexone; 2.8 doses after placebo). Ethanol produced its prototypic subjective effects (e.g., increased ratings of "feel drug", "like drug" and "high"), and these effects were not altered by naltrexone. Naltrexone produced mild sedative-like effects, and several subjects reported adverse effects such as nausea. CONCLUSIONS: These findings show that naltrexone reduces ethanol consumption in healthy volunteers, as it does in alcoholics. However, this reduction was not specific to alcohol; subjects also consumed less of a non-alcoholic, placebo beverage. These findings suggest that naltrexone may reduce alcohol consumption by a non-specific mechanism.

Adult↗
PubMed1999

Fragile-X syndrome, Down's syndrome and autism: awareness and knowledge amongst special educators.

Fragile-X syndrome is the commonest cause of inherited intellectual disability. There is good evidence for a behavioural phenotype. This has implications for school staff using standard educational techniques. Similarly, autism is known to create particular educational requirements. The present study examined the awareness and knowledge of fragile-X syndrome, Down's syndrome and autism amongst staff in special and mainstream education. One hundred and two special school staff and 40 mainstream school staff completed questionnaires. Most staff offered a variety of features 'typical' of Down's syndrome and autism. In contrast, staff knew less about fragile-X syndrome. Specific knowledge about the learning styles of these children was very poor, but was associated with having taught an affected child. Mainstream and special school staff offered similar levels of knowledge for all three conditions. Staff did not demonstrate a sufficiently specialized knowledge of fragile-X syndrome to ensure that the special educational needs of these children were being met fully.

Adult↗
PubMed1999

Environmental imperatives reconsidered: demographic crises in western North America during the medieval climatic anomaly.

Review of late Holocene paleoenvironmental and cultural sequences from four regions of western North America show striking correlations between drought and changes in subsistence, population, exchange, health, and interpersonal violence during the Medieval Climatic Anomaly (A.D. 800-1350). While ultimate causality is difficult to identify in the archaeological record, synchrony of the environmental and cultural changes and the negative character of many human responses--increased interpersonal violence, deterioration of long-distance exchange relationships, and regional abandonments--suggest widespread demographic crises caused by decreased environmental productivity. The medieval droughts occurred at a unique juncture in the demographic history of western North America when unusually large populations of both hunter-gathers and agriculturalists had evolved highly intensified economies that put them in unprecedented ecological jeopardy. Long-term patterns in the archaeological record are inconsistent with the predicted outcomes of simple adaptation or continuous economic intensification, suggesting that in this instance environmental dynamics played a major role in cultural transformations across a wide expanse of western North America among groups with diverse subsistence strategies. These events suggest that environment should not be overlooked as a potential cause of prehistoric culture change.

Climate↗
PubMed1997

Interleukin-2 after autologous stem cell transplantation for hematologic malignancy: a phase I/II study.

The success of autologous stem cell transplantation (ASCT) for hematologic malignancy is limited largely by a high relapse rate. It is postulated that IL-2 administered after ASCT may eliminate minimal residual disease and thereby reduce relapses. A phase I/II study was performed to identify a regimen of IL-2 (Chiron) that could be given early after ASCT in phase III trials. In the phase I study, beginning a median of 46 days after ASCT for hematologic malignancy, cohorts of three to four patients received escalating doses of 'induction' IL-2 of 9, 10, or 12 x 10(6) IU/m2/day for 4 or 5 days by continuous i.v. infusion (CIV), followed by a 4-day rest period, and then 1.6 x 10(6) IU/m2/day of maintenance IL-2 by CIV for 10 days. The maximum tolerated dose (MTD) of induction IL-2 was 9 x 10(6) IU/m2/day x 4. In the phase II study, 52 patients received the MTD. Eighty percent of patients completed induction IL-2. Most patients exhibited some degree of capillary leak. One patient died of CMV pneumonia and one died of ARDS. Maintenance IL-2 was well tolerated. In the phase I/II study, 16 of 31 patients with non-Hodgkin lymphoma (NHL), 3/8 with Hodgkin disease (HD), 4/17 with AML, and 4/5 with ALL remain in CR. Two of six multiple myeloma (MM) patients remain in PR. Although the regimen of IL-2 identified had significant side-effects in some patients, it was well tolerated in the majority of patients. Phase III prospectively randomized clinical trials are in progress to determine if this IL-2 regimen will decrease the relapse rate after ASCT for AML and NHL.

Adjuvants, Immunologic↗
PubMed1996

Close simulation of acute graft-versus-host disease by interleukin-2 administered after autologous bone marrow transplantation for hematologic malignancy.

The high relapse rate of hematologic malignancy treated with autologous bone marrow transplantation (ABMT) may reflect the absence of a graft-versus-leukemia (GVL) effect usually associated with graft-versus-host disease (GVHD). The purpose of this study was to determine whether administration of interleukin-2 (IL-2) early after ABMT might induce or exacerbate acute skin GVHD. Fourteen patients at high risk for post-transplant relapse, eight with NHL and six with AML > or = first relapse, were conditioned with chemotherapy and total body irradiation (13) or chemotherapy alone (1), and received purged (10) or unpurged (4) marrow. A median of 35 days (range 25-58) after ABMT, they received a 5-day induction course of Roche IL-2 (9 x 10(6) U/m2/day) followed by apheresis, reinfusion of LAK cells, and a 10-day maintenance course of IL-2 (0.9 x 10(6) U/m2/day), all by continuous i.v. infusion. Serial skin biopsies were obtained before and after IL-2 therapy and were read blindly. Patients were studied prospectively for the development of acute cutaneous GVHD as reflected by rash ( > or = 25% body surface area), skin biopsy ( > or = grade II histologic changes) and T cell infiltration as assessed by staining of the biopsy with antibodies UCHL-1 and TIA-1. No patient had a rash before IL-2 therapy, but 12 of 14 (85%) developed a rash during the IL-2 induction course. Before IL-2 therapy, biopsies from three of 10 patients (30%) revealed histologic GVHD; after induction IL-2, biopsies from 11 of 14 patients (79%) revealed grade II acute GVHD. Biopsies from all patients with histologic GVHD after IL-2 therapy contained TIA-1 positive T cells. HLA-DR was negative in the keratinocytes of these paraffin-embedded sections. One patient died early of sepsis, one patient required and responded to topical corticosteroids and 12 had spontaneous resolution of the rash. Six patients relapsed at 3-13 months, while seven remain in complete remission 32+ to 41+ months after ABMT. The results demonstrate that IL-2 therapy after ABMT can induce effects which histologically and clinically mimic cutaneous acute GVHD in most patients. Prospective, randomized trials of IL-2 vs observation after transplantation of autologous marrow or stem cells for high-risk NHL and AML have been initiated which may allow us to determine whether this phenomenon is associated with a clinical GVL effect as reflected by a decreased relapse rate.

Acute Disease↗
PubMed1995

Population pharmacodynamics of romazarit.

1. The response to romazarit, a disease modifying anti-rheumatoid agent, was observed in patients with rheumatoid arthritis (RA) in a double-blind placebo controlled study. 2. Two hundred and twenty-four patients were recruited from 11 centres and treated with placebo or romazarit at a dose of 200 mg or 450 mg every 12 h for up to 24 weeks. Disease activity was measured using the Ritchie Index (RI). Plasma concentrations of romazarit were measured at each of up to eight assessments of RI. 3. The effect of romazarit was examined using analysis of variance (ANOVA) in 164 patients who contributed 61% of observations of disease activity. Observations after 12 weeks of treatment were excluded from ANOVA. 4. A population pharmacokinetic-dynamic model for the time course of disease progress and the response to placebo and romazarit was used to describe observations from all patients. 5. The population model suggested that the effect of romazarit was on the rate of progress of the disease and was describable by an Emax model. Concentration was a better predictor of response than dose. 6. Romazarit was significantly better than placebo in improving the RI in patients with RA. The placebo efficacy of romazarit treatment was similar to that associated with placebo treatment. 7. The population model provided a more complete description and explanation of the clinical pharmacology and therapeutic potential of romazarit than ANOVA.

Administration, Oral↗
PubMed1995

Immunotherapy with interleukin 2 with or without lymphokine-activated killer cells after autologous bone marrow transplantation for malignant lymphoma: a feasibility trial.

Early relapse remains a major challenge after autologous bone marrow transplant for malignant lymphoma (ML). It is postulated that consolidative immunotherapy with interleukin 2 (IL-2) with or without lymphokine-activated killer (LAK) cells administered after autologous bone marrow (ABMT) or peripheral blood stem cell transplantation (PBSCT) for ML might eradicate residual disease and reduce relapse rates. A previous trial identified an IL-2 regimen that could be administered early after ABMT. This paper presents the clinical results of 16 patients with ML, who participated in a study to determine whether LAK cells could be administered after ABMT with this IL-2 regimen, as well as 6 patients who received IL-2 alone after ABMT or PBSCT. Seventeen patients with non-Hodgkin's lymphoma (NHL), and 5 with Hodgkin's disease (HD), underwent ABMT (20 patients) or PBSCT (2 patients). At the time of transplantation, 7 patients were in untreated or chemotherapy-sensitive first relapse, 3 were in CR2, and 12 were beyond CR2. Beginning 22-85 days (median 43) after ABMT/PBSCT, patients received IL-2 at 3.0 x 10(6) U/m2/day by continuous infusion days 1-5 of the IL-2 protocol. On protocol days 7-9 the first 16 patients underwent apheresis for LAK cell generation. The cells were cultured in IL-2 for 5 days and were infused on days 12-14. Low-dose IL-2 (0.9 x 10(6) IU/m2/day) was administered on days 12-21 in the outpatient department. Patients received a median of 148 (62-279) x 10(9) LAK cells. LAK cell infusions were associated with transient fevers, chills and dyspnea in most patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Designing a standardized oral health survey for the tri-services.

To address a Congressional directive for a comprehensive study of the military medical care system (including dental care), the Tri-Service Dental Chiefs convened a panel of dental epidemiologists to develop a standardized protocol for assessing the oral health of soldiers, sailors, and airmen. This paper discusses previous military and civilian oral health surveys and outlines key design features of the common military protocol that evolved from this critical review of the literature.

Adolescent↗
PubMed1993

Interleukin-2 +/- lymphocytes as consolidative immunotherapy after autologous bone marrow transplantation for hematologic malignancies.

Patients who undergo autologous bone marrow transplantation (ABMT) for advanced hematologic malignancies experience a high relapse rate. Therapy with interleukin-2 (IL-2) +/- lymphokine-activated killer (LAK) cells has induced clinical responses in some patients with advanced malignant lymphoma (ML) or acute myelogenous leukemia (AML). It is postulated that IL-2 +/- LAK cells represents a potentially non-cross-resistant therapeutic modality which might prevent or delay relapses if used as consolidative immunotherapy after ABMT, at a time of minimal residual disease. Therefore, we first studied the reconstitution of IL-2-responsive LAK precursor cells after ABMT and found them in the circulation as early as 3 weeks after ABMT. A phase Ib clinical trial was then performed which identified a tolerable IL-2 regimen which could be administered early after ABMT and which could induce immunomodulatory effects. We then initiated a clinical trial to determine the feasibility of generating and administering autologous LAK cells using this IL-2 regimen after ABMT for 16 patients with ML. The results show that IL-2+LAK therapy early after ABMT is feasible but is more toxic than IL-2 alone. Patients with AML on the phase I IL-2 trial and with ML on the IL-2+LAK protocol were evaluated for tumor status. Of 8 patients with AML in first relapse or at a later stage who underwent ABMT and received IL-2, 2 have relapsed, while 6 remain in complete remission 26+ to 40+ (median 28+) months after ABMT. Of 16 patients with ML considered at high risk for relapse who were treated with ABMT+IL-2+LAK, 5 have relapsed, while 11 remain in complete remission at 6+ to 21+ (median 10+) months after ABMT. The results in both trials are quite encouraging and appear to be better than those in nonrandomized historical controls at our institution. Prospectively randomized trials of IL-2 versus no IL-2 after ABMT in such patients are being initiated to assess definitively the effect, if any, on the relapse rate.

Bone Marrow Transplantation↗
PubMed1993

Athletic trainer utilization in sports medicine clinics.

Increased use of athletic trainers in sports medicine clinics has created a need for information related to actual and ideal use of these professionals in these settings. The purposes of this study were to 1) describe the characteristics of sports medicine clinics and their personnel, 2) determine whether there were differences between opinions of certified athletic trainers (ATCs), physical therapists (PTs), and professionals with dual credentials (PT/ATCs) about the ideal role of the ATC in sports medicine clinics, and 3) determine whether there were differences in actual usage of ATCs between states with and without athletic training laws. Subjects included 46 PTs, 43 PT/ATCs, and 73 ATCs from six different states. A questionnaire ascertained opinions about ideal ATC utilization and about current practice of ATCs with respect to 28 different clinical procedures. For 27 of the 28 procedures, there were significant differences of opinion about ideal ATC utilization between individuals with the three credentials. No significant differences in actual athletic trainer use in sports medicine clinics were found between states with and without athletic training laws.

Adult↗
PubMed1993

Interleukin-2 with or without lymphokine-activated killer cells as consolidative immunotherapy after autologous bone marrow transplantation for acute myelogenous leukemia.

IL-2 with or without autologous lymphokine-activated killer (LAK) cells, administered early after ABMT for AML may eradicate residual disease and reduce relapses. This paper reports 14 patients who received IL-2 or IL-2 plus LAK cells after ABMT for AML in first relapse or at a later stage, in two separate trials. Patients with AML in first relapse (n = 9), second CR (n = 3) or second relapse (n = 2) underwent ABMT after busulfan (BU), CY and total body irradiation (n = 11) or BU/CY alone (n = 3), with marrow that was (n = 6) or was not (n = 8) purged with 4-HC. In a previously-reported Phase I trial, eight patients received IL-2 (Roche) by continuous infusion at 0.3-3.0 x 10(6) U/m2/day x 5 days and, after 6 days of rest, 0.3 x 10(6) U/m2/day x 10 days. In a subsequent trial, five patients received IL-2 at 3.0 x 10(6) U/m2/day x 5 days, underwent leukapheresis for 3 days and received their LAK cells plus IL-2 (0.3 x 10(6) U/m2/day x 10 days). A sixth patient received only 2 days of IL-2, developed sepsis and died of multiorgan failure. All other patients had mild to moderate toxicity which was reversible. All patients developed neutrophilia, lymphocytosis and thrombocytopenia. IL-2 with or without LAK therapy was initiated 21-91 days (median 51 days) after ABMT. Severe thrombocytopenia (< 10 x 10(9)/l) occurred during the apheresis days.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

A pharmacokinetic and tolerance study of romazarit in patients with rheumatoid arthritis.

Romazarit is a new drug for which animal pharmacology suggests a disease-modifying action in rheumatoid arthritis (RA). These animal studies predict that plasma romazarit concentrations within the range 50-100 mg l-1 may be required for efficacy in the clinic. Therefore, a pharmacokinetic study was designed to estimate the dosage required to achieve these concentrations in man. Twenty-four patients with RA entered a double-blind controlled assessment receiving either placebo, 100 mg t.i.d., 350 mg b.i.d., or 350 mg t.i.d., for 6 days. Pharmacokinetic profiles were measured after single doses and after the last of the multiple doses. Adverse events were mainly trival and were distributed almost equally between all three treatment and the placebo groups. Plasma romazarit concentrations were not dose-proportional after the single doses. Mean peak plasma drug concentrations were 11.8, 66.7, and 159 mg l-1 at steady state after 100 mg t.i.d., 350 mg b.i.d., and 350 mg t.i.d. The mean urinary recovery of drug-related material (mostly ester glucuronides) was 71 per cent of the dose during the dosage interval. The renal clearance of romazarit glucuronides correlated with creatinine clearance (p less than 0.01). Saturable tubular secretion of glucuronides coupled with reversible glucuronidation would explain these findings. It is predicted that oral doses of 450 mg romazarit given 12-hourly will result in plasma concentrations within the target range of 50-100 mg l-1.

Administration, Oral↗