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Biomedical subjects

C Collier

Publications and source records attributed to C Collier.

At least 19 recordsLinked to original sources
PubMed1998

Acute asthma epidemics, weather and pollen in England, 1987-1994.

Recent epidemics of acute asthma have caused speculation that, if their causes were known, early warnings might be feasible. In particular, some epidemics seemed to be associated with thunderstorms. We wondered what risk factors predicting epidemics could be identified. Daily asthma admissions counts during 1987-1994, for two age groups (0-14 yrs and > or = 15 yrs), were measured using the Hospital Episodes System (HES). Epidemics were defined as combinations of date, age group and English Regional Health Authority (RHA) with exceptionally high asthma admission counts compared to the predictions of a log-linear autoregression model. They were compared with control days 1 week before and afterwards, regarding seven meteorological variables and 5 day average pollen counts for four species. Fifty six asthma epidemics were identified. The mean density of sferics (lightning flashes), temperature and rainfall on epidemic days were greater than those on control days. High sferics densities were overrepresented in epidemics. Simultaneously high sferics and grass pollen further increased the probability of an epidemic, but only to 15% (95% confidence interval 2-45%). Two thirds of epidemics were not preceded by thunderstorms. Thunderstorms and high grass pollen levels precede asthma epidemics more often than expected by chance. However, most epidemics are not associated with thunderstorms or unusual weather conditions, and most thunderstorms, even following high grass pollen levels, do not precede epidemics. An early warning system based on the indicators examined here would, therefore, detect few epidemics and generate an unacceptably high rate of false alarms.

Adolescent↗
PubMed1997

Application of AN69 hydrogel to islet encapsulation. Evaluation in streptozotocin-induced diabetic rat model.

The polymer AN69 (polyacrylonitrile-sodium methallylsulfonate) is a reference in biocompatibility in the field of hemodialysis. Its use for the encapsulation of living cells has been already described, but this study is the first description of AN69 hydrogel-encapsulated islet isograft in streptozotocin (STZ) diabetic rats. The aim of this work is to evaluate the biocompatibility of the AN69 hydrogel by comparison of the efficacy of free versus encapsulated islets transplanted to balance diabetes. Pancreatic islets are isolated from adult male Lewis rats by a standard collagenase digestion and purified on Ficoll density gradients. The AN69 hollow fiber is obtained by coextrusion of an 8% AN69 collodion. The hollow fiber is filled with islets suspended in agarose at the final concentration of 10,000 islets/ml, closed with surgical clips and implanted. The recipients are rendered diabetic by intravenous injection of STZ. The experimental design includes 4 groups of 8 rats: group 1: control, group 2: diabetic rats intraperitoneally implanted with 6000 free islets, group 3: diabetic rats intraperitoneally implanted with 9000 encapsulated islets, group 4: diabetic control. Weight and fasting glycemia are evaluated twice a week, diuresis once a week. After free islet implantation, rat survival is improved with glycemia below 250 mg/dl during 22 days. Compared to group 2, the status of group 3 is better, with a glycemia below 250 mg/dl during at least 70 days. This tends to demonstrate the biocompatibility of AN69 and is the first step of the validation of the use of AN69 for living cell encapsulation.

Acrylic Resins↗
PubMed1997

Transdermal fentanyl as treatment for chronic low back pain.

Management of chronic low back pain often includes oral opioid use. The effectiveness of therapy is dependent upon compliance, which in turn is dependent upon response, side effects, access, and convenience. Our hypothesis was that a transdermal fentanyl system would provide more effective pain management than oral opioids. Fifty patients with chronic low back pain were examined. After litration to levels corresponding to current oral opioid use, each patient was maintained on transdermal fentanyl for one month. Oral opioid therapy was then resumed. Their experience was assessed with the a visual analogue scale for pain intensity, a numerical pain score, the Oswestry disability questionnaire, the pain disability index, and the Verran Snyder-Halpern sleep scale. Significant improvement in pain relief and disability was found with transdermal fentanyl compared with oral opioids. Mild opioid side effects were common, but easily controlled. Use of transdermal fentanyl is an effective alternative to oral opioids for managing chronic low back pain.

Administration, Cutaneous↗
PubMed1997

Effect of thunderstorms and airborne grass pollen on the incidence of acute asthma in England, 1990-94.

BACKGROUND: Thunderstorms and prior grass pollen counts were investigated as predictors of daily hospital admissions for asthma in England. This study was motivated by reports in the literature of spectacular asthma epidemics associated with thunderstorms, particularly in the grass pollen season. METHODS: Asthma admissions for two age groups (0-14 years and 15 and over) were measured using the Hospital Episodes System (HES) in the 14 regional health authorities (RHAs) in England. Thunderstorms were measured daily in each RHA using densities of sferics (lightning flashes). Relative asthma excesses for moderate positive and exceptionally high sferic densities, with or without previous high grass pollen counts, were measured using log linear autoregression--allowing for weekly, seasonal, and longer term background variation--and pooled over RHAs by calculating geometric means. RESULTS: Relative risks from all RHAs were pooled to form geometric means. Exceptional sferic densities were associated with a relative excess risk of around 25% in both age groups. Moderate sferic densities were associated with a smaller excess, statistically significant in the two age groups taken together. In five RHAs in which grass pollen counts were available, high pollen counts for the previous five days were associated with an amplification of the excess associated with thunderstorms. CONCLUSION: Very large sferic densities are associated with moderate rises in hospital admissions for acute asthma. However, typical thunderstorm days are not associated with spectacular asthma epidemics of the scale previously reported in the literature. Thunderstorm-associated excesses are amplified after a run of high pollen counts.

Acute Disease↗
PubMed1997

A community waterborne outbreak of salmonellosis and the effectiveness of a boil water order.

OBJECTIVES: A 1993 large water-borne outbreak of Salmonella typhimurium infections in Gideon, Mo, a city of 1100 with an unchlorinated community water supply, was investigated to determine the source of contamination and the effectiveness of an order to boil water. METHODS: A survey of household members in Gideon and the surrounding township produced information on diarrheal illness, water consumption, and compliance with the boil water order. RESULTS: More than 650 persons were ill; 15 were hospitalized, and 7 died. Persons consuming city water were more likely to be ill (relative risk [RR] = 9.1, 95% confidence interval [CI] = 2.9, 28.4), and the attack rate increased with increased water consumption. S. typhimurium was recovered from samples taken from a city fire hydrant and a water storage tower. Persons in 31% (30/ 98) of city households had drunk unboiled water after being informed about the boil water order, including 14 individuals who subsequently became ill. Reasons for noncompliance included "not remembering" (44%) and "disbelieving" (25%) the order. CONCLUSIONS: Communities with deteriorating water systems risk widespread illness unless water supplies are properly operated and maintained. Effective education to improve compliance during boil water orders is needed.

Data Collection↗
PubMed1997

Factors associated with client-reported HIV infection among clients entering methadone treatment.

To determine demographic and behavioral factors associated with client-reported HIV infection among new enrollees in methadone maintenance treatment programs (MMTPs) in Massachusetts and Connecticut, we examined ethnographic data and interview data from MMTP clients (N = 674). Clients responded to questions about behaviors in the 30 days before drug treatment. ETHNOGRAPH was used to analyze qualitative data, and logistic regression analysis was used to identify variables associated with client-reported HIV infection. Statistical significance was set at p < .05. The client-reported HIV infection rate was 20% (132/674). Odds ratios for factors associated with client-reported HIV infection were being white (0.53), increase in age (1.07), use of non-injected heroin (0.12), use of injected heroin (6.24), cocaine injection (1.78), sharing of "works" with strangers (2.15), and "safer sex" behavior (4.04). Additionally, 35% of those who did not use illicit drugs reported being seropositive. The qualitative data suggested HIV positive clients were concerned about protecting sex partners, and learning of HIV infection motivated some to stop using drugs. Although some clients engaged in low-risk behaviors, others did not, therefore the potential for HIV transmission among injection drug users (IDUs) in Connecticut and Massachusetts exists. HIV prevention and drug treatment program personnel should reinforce and build on the low-risk behaviors that are acceptable and adopted by some in this population.

Adult↗
PubMed1995

Preoperative chemoradiation for adenocarcinoma of the pancreas: excessive toxicity of prophylactic hepatic irradiation.

PURPOSE: In an effort to reduce relapse in the liver and improve survival in patients with potentially resectable adenocarcinoma of the pancreatic head, we combined whole-liver irradiation with our standard preoperative chemoradiation regimen. METHODS AND MATERIALS: Eleven patients with biopsy-proven, potentially resectable adenocarcinoma of the pancreatic head were treated with 50.4 Gy of external beam irradiation to the pancreas (1.8 Gy/day, 5 days/week) and concurrent continuous infusion 5-fluorouracil (300 mg/m2 per day). The liver was treated with 23.4 Gy on Days 8 through 21 (13 fractions; 1.8 Gy/fraction). Patients, who upon restaging with radiography and computed tomography were considered to have resectable tumors, were subsequently taken to surgery. If, at surgery, tumors were resectable, pancreaticoduodenectomy was performed, and 10 Gy of intraoperative electron-beam radiation therapy was delivered to the bed of the resected pancreas. RESULTS: All 11 patients completed chemoradiation. Two treatment-related deaths occurred following chemoradiation, prompting premature termination of the study. Of seven patients taken to surgery, four underwent resection. Seven patients have died of disease, five with liver metastases. CONCLUSIONS: Prophylactic hepatic chemoradiation, as given in this study, was associated with two treatment-related deaths and a higher than expected incidence of subsequent liver metastases. Our data do not support the use of this treatment program in patients with adenocarcinoma of the pancreas.

Adenocarcinoma↗
PubMed1994

Monitoring of monoclonal gammopathies: rational use of densitometry and rate nephelometry.

The follow-up of patients with monoclonal gammopathies at our institution includes serial serum protein electrophoresis (SPE) with densitometry and IgG, IgA, and IgM quantitative immunoglobulin (QIG) determinations by rate nephelometry. This retrospective audit compares monoclonal protein concentration as estimated by SPE versus QIG in 456 serial serum specimens from 105 patients to determine whether any of the tests provide redundant information. A comparison of the methods demonstrated good correlation between SPE (x-axis) and QIG (y-axis) quantitation for each immunoglobulin class: IgG had a slope of 1.45 and an intercept of 1.60 (Sy/x = 7.46, r = 0.96, n = 250); IgA had a slope of 1.30 and an intercept of -1.37 (Sy/x = 6.85, r = 0.96, n = 78); and IgM had a slope of 1.95 and an intercept of 2.06 (Sy/x = 5.16, r = 0.98, n = 128). The data for individual patients showed similar good correlations. Exceptions included IgA peaks "buried" in the beta region of the SPE (resulting in invalid SPE estimates of monoclonal protein concentration), and IgG peaks of less than 10 g/L (when background polyclonal IgG immunoglobulin skews the QIG estimate of monoclonal protein concentration). An algorithm is proposed whereby monoclonal protein concentration is measured by the specific QIG (i.e., IgG, IgA, or IgM) determination for the routine monitoring of patients, except for those with IgG peaks of less than 10 g/L that are followed by SPE.

Blood Protein Electrophoresis↗
PubMed1994

Preliminary report on cell encapsulation in a hydrogel made of a biocompatible material, AN69, for the development of a bioartificial pancreas.

The occurrence of an inflammatory reaction represents the major obstacle to the development of any implantable system including micro and macroencapsulation. The purpose of this study was to describe an encapsulation method for cells using a membrane made of AN69, a copolymer of acrylonitrile which is considered as a reference in biocompatibility in the field of haemodialysis. The hydrogel of AN69 was obtained after a coagulation step at room temperature followed by a solvent/non-solvent (water) exchange phase. Microcapsules were obtained by co-extrusion of AN69 collodion and saline (with or without cells). The function of encapsulated cells was assessed in vitro, demonstrating cell survival after the microencapsulation procedure. These preliminary data are consistent with the potential interest for the development of the microencapsulation procedure aimed at realising a bioartificial pancreas.

Acrylic Resins↗
PubMed1992

Minimodule dialyser for quantitative ex vivo evaluation of membrane haemocompatibility in humans: comparison of acrylonitrile copolymer, cuprophan and polysulphone hollow fibres.

Minimodule hollow fibre dialysers, representing clinical dialysis modules on a scale of 1/25, enable quantitative evaluation of the haemocompatibility of hollow fibre membranes in an ex vivo flow system in humans. On line heparinization, adjusted for donor sensitivity, is maintained at a minimal level (approximately 0.14 units/ml). Blood samples collected at the minimodule exit over 30 min are analysed for heparin (anti-Xa activity), activated partial thromboplastin time, fibrinopeptide A, platelet count and beta-thromboglobulin, complement fragment C3a, leucocyte count and polymorphonuclear neutrophil elastase. Initial experiments were performed using well-characterized reference materials: acrylonitrile copolymer (AN 69 HF), polysulphone and cuprophan (CUP). Activation of coagulation and platelets was low for AN 69 HF, intermediate for CUP and greatest for polysulphone, while complement activation was negligible in the presence of AN 69 HF, moderate for polysulphone and most important for CUP. Future applications will be directed towards haemocompatibility screening of prototype membranes with the aim of developing clinical dialysers with improved biocompatibility.

Acrylic Resins↗