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PubMed1988

[Evaluation of an automated system of measuring erythrocyte aggregation in dysglobulinemia treated by plasma exchange].

Characteristics of a new erythrocyte aggregameter were evaluated in 7 patients with monoclonal dysglobulinemia (5 multiple myeloma, 1 Waldenström disease, 1 CLL with monoclonal immunoglobulin) treated by plasma exchange. This apparatus measures modifications of light retro-diffused by erythrocytes suspension after shear arrest. All parameters measured: Ta, Tf, S10, gamma D, gamma S were modified after plasma exchange: either immediately after the first or after the second or third plasma exchange. These findings demonstrate the value of this new technique for evaluating red cell aggregation. These data should be completed by rheological assessment of dysglobulinemia treated by plasma exchange.

Automation↗

PubMed2006

The Danish effect on Swedish alcohol costs. An analysis based on hospitalization data from southern Sweden.

This study investigated: (a) the cost and change in hospitalizations related to alcohol misuse for the healthcare sector and (b) the effect of distance to the border on alcohol-related hospitalization costs. The first objective was analyzed using descriptive statistics and the second using ordinary least squares regression on aggregated municipality data. The total cost decreased marginally during the study period while the number of patient-cases decreased substantially, presenting evidence of a substitution towards outpatient care. The increase in average treatment cost and the almost constant total cost provide evidence for a societal increase in the burden of alcohol-related diseases. We found a negative effect for distance to Denmark on alcohol-related hospitalization cost for the year 2003. The effect was smaller for 1998, suggesting that the increase in private import quotas during the study period has affected individuals' consumption level and/or consumption pattern. We also found indications that the increase in import quotas lead to a higher cost increase for heavy consumers than for low consumers.

Adolescent↗

PubMed2005

Effect of head group polarity and spacer chain length on the aggregation properties of gemini surfactants in an aquatic environment.

The aggregation behavior of cationic gemini surfactants with respect to variation in head group polarity and spacer length is studied through conductance, surface tension, viscosity, and small-angle neutron-scattering (SANS) measurements. The critical micellar concentration (cmc), average degree of micelle ionization (beta(ave)), minimum area per molecule of surfactant at the air-water interface (A(min)), surface excess concentration (gamma(max)), and Gibb's free energy of micellization (delta G(mic)) of the surfactants were determined from conductance and surface tension data. The aggregation numbers (N), dimensions of micelles (b/a), effective fractional charge per monomer (alpha), and hydration of micelles (h(E)) were determined from SANS and viscosity data, respectively. The increasing head group polarity of gemini surfactant with spacer chain length of 4 methylene units promotes micellar growth, leading to a decrease in cmc, beta(ave), and delta G(mic) and an increase in N and b/a. This is well supported by the observed increase in hydration (h(E)) of micelles with increase in aggregation number (N) and dimension (b/a) of micelle.

Journal Article↗

PubMed1971

In vitro aggregation of mixed embryonic kidney and nerve cells. Influence on macromolecular synthesis.

The possible role of nerve on growth of embryonic parenchymal organs such as kidney was explored by measuring macromolecular synthesis (DNA, RNA, and protein and three enzymes) in aggregates of mixed suspensions of cells from dissociated chick embryo kidney and nerve tissue. One and one-half to threefold increments in net synthesis of the three different types of macromolecules were observed in the mixed aggregates of kidney and nerve cells as compared with those of single organs or mixtures of kidney with nonneural cells. The addition of nerve-growth factor (NGF) did not significantly affect the results. Increased incorporation of label was paralleled by increases in chemically measured DNA and protein, suggesting an increase in growth in the mixed kidney-nerve aggregates compared with those of single tissues. Measurements of survival rate did not indicate increased cell stability in the mixed aggregates. The activities of three enzymes, acid phosphatase, alkaline phosphatase, and lactic dehydrogenase, were also enhanced two to four times in cultures of kidney plus nerve cells. Morphologic studies indicated a high degree of reorganization of tubular structures within the reaggregates of kidney cells alone or in those mixed with nerve. In addition, radioautographs of thymidine-(3)H-labeled cells in the aggregates showed a high level of DNA synthesis in the reformed tubular cells. Electron micrographs revealed the presence of large numbers of nerve fibers containing microtubules in the mixed cell aggregates. The data suggest a significant role for nerve in the growth processes of embryonic parenchymal organs.

Acid Phosphatase↗

PubMed2004

Prediction of tracheostomy tube size for paediatric long-term ventilation: an audit of children with spinal cord injury.

BACKGROUND: There are no published data to predict tracheostomy tube size as growth proceeds in children requiring long-term ventilation. METHODS: A retrospective audit was undertaken of children having long-term ventilation, managed from the Southport spinal injuries unit. The dates of step-up in size of tracheostomy tube were noted together with the tube inside and outside diameters (ID and OD) and the lateral tracheal diameter. The data were aggregated for each increment in tube size to calculate the Pearson correlation coefficients for age and weight of the children. Linear regression was then used to generate predictive equations based on age and weight. RESULTS: Out of 12 children, data from seven boys and two girls, with a mean age of 5.9 (range 1.5-13.75) yr, were obtained. Average length of follow-up was 7 yr, with an average of 3.5 tube changes per patient equating to a larger tube every 2 yr. The inside and outside tracheal tube diameters, as well as the lateral tracheal diameter, correlated significantly with age and weight (P<0.01). The appropriate tracheostomy tube internal diameter is conveniently expressed by the formula: ID mm=age yr/3 + 3.5 CONCLUSIONS: The step-up in size of the tracheostomy tube as growth proceeds should be undertaken as a planned procedure at least every 2 yr to avoid nocturnal desaturation. Age appears to be a convenient and reliable predictor.

Adolescent↗

PubMed2001

Therapy for Helicobacter pylori in patients with nonulcer dyspepsia. A meta-analysis of randomized, controlled trials.

PURPOSE: To assess the effect of eradication therapy for Helicobacter pylori on symptoms of nonulcer dyspepsia. DATA SOURCES: Duplicate searches of bibliographic databases, reviews of proceedings of annual gastroenterology and H. pylori meetings from 1995 to 1999, reviews of reference lists, and contact with primary investigators and pharmaceutical manufacturers. STUDY SELECTION: Included studies 1) examined patients with nonulcer dyspepsia and H. pylori infection; 2) used combination therapy for H. pylori and a control therapy without efficacy against H. pylori; 3) were randomized, controlled trials; 4) lasted for at least 1 month after the end of therapy; and 5) assessed symptoms of nonulcer dyspepsia. Ten studies were included. DATA EXTRACTION: Independent, duplicate data extraction of the methodologic quality, population, intervention, study design, duration, and outcome of the trials. DATA SYNTHESIS: The odds ratio (OR) for treatment success in nonulcer dyspepsia with H. pylori eradication therapy compared with control therapy was 1.29 (95% CI, 0.89 to 1.89; P = 0.18). However, significant heterogeneity (P = 0.04) calls the validity of aggregating the data into question. Heterogeneity resolved with the exclusion of one study (OR, 1.07 [CI, 0.83 to 1.37]; P > 0.2). For predefined analysis of trials that used a specifically stated definition of dyspepsia (that is, upper abdominal pain or discomfort), the OR was 1.04 (CI, 0.80 to 1.35) without heterogeneity. For treatment that resulted in cure rather than persistent infection, the OR was 1.17 (CI, 0.87 to 1.59) without heterogeneity. CONCLUSION: This meta-analysis provides little support for the use of H. pylori eradication therapy in patients with nonulcer dyspepsia.

Anti-Bacterial Agents↗

PubMed1995

Tests of random mating for a highly polymorphic locus: application to HLA data.

Testing for random mating at an HLA locus is a difficult problem because of the highly polymorphic nature of the HLA loci. We discuss some methodological issues and propose several tests. A simulation study is conducted to evaluate these tests. The single allele test and the shared allele test deal with small sample sizes by aggregating the data in different ways. The shared allele test is found to be a more powerful method of detecting non-random mating patterns involving a deficiency or an excess of similar genotypes than the single allele test. We show that random mating of couple at the genotype level implies the random mating of couple at the allele level. Several multi-allele approaches are proposed for large population-based data sets. Among them, the corrected allele-table test performs better than the generalized Wald test in terms of power and size. These methods are then applied to an HLA data set of Caucasian couples, and no solid evidence for non-random mating at the HLA A, B, and DR loci is found.

Alleles↗

PubMed2001

Peptide models of the helical hydrophobic transmembrane segments of membrane proteins: interactions of acetyl-K2-(LA)12-K2-amide with phosphatidylethanolamine bilayer membranes.

High-sensitivity differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy were used to study the interaction of a synthetic alpha-helical hydrophobic transmembrane peptide, acetyl-Lys(2)-(Leu-Ala)(12)-Lys(2)-amide [(LA)(12)], and members of a homologous series of n-saturated diacylphosphatidylethanolamines (PEs). In the lower range of peptide mole fractions, the DSC endotherms exhibited by the lipid/peptide mixtures consist of two components. The temperature and cooperativity of the sharper, higher temperature component are very similar to those of pure PE bilayers and are almost unaffected by variations in the protein/lipid ratio. However, the fractional contribution of this component to the total enthalpy changes decreases with increases in peptide concentration, and this component completely disappears at higher protein mole fractions. The other component, which is less cooperative and occurs at a lower temperature, predominates at higher protein concentrations. These two components of the DSC endotherm have been assigned to the chain-melting phase transitions of peptide-nonassociated and peptide-associated PE molecules, respectively. Although the temperature at which the peptide-associated PE molecules melt is progressively decreased by increases in (LA)(12) concentration, the magnitude of this downward shift is progressively greater as the length of the PE hydrocarbon chain decreases. As well, mixtures of (LA)(12) with the longer chain PEs exhibit unusual biomodal enthalpy variations, suggesting peptide immiscibility in thicker gel state bilayers. Moreover, the enthalpy of the chain-melting transition of the peptide-associated PE does not decrease to zero even at high peptide concentrations, indicating that (LA)(12) attenuates but does not abolish the cooperative gel/liquid-crystalline phase transition of the lipids with which it is in contact. Our FTIR spectroscopic data indicate that (LA)(12) remains in a predominantly alpha-helical conformation in liquid-crystalline PE bilayers of various hydrophobic thickness but that the helical conformation is altered in gel-state PE bilayers generally, probably due to peptide lateral aggregation. These data also suggest that (LA)(12) significantly disorders the hydrocarbon chains of adjacent PE molecules in both the gel and liquid-crystalline states, relatively independently of lipid hydrocarbon chain length. Many aspects of PE/(LA)(12) interactions exhibit a different dependence on the hydrophobic thickness of the host bilayer than was observed in our previous study of (LA)(12)-phosphatidylcholine (PC) model membranes [Zhang et al. (1995) Biochemistry 34, 2362-2371]. The differing effects of (LA)(12) incorporation on PE and PC bilayers is ascribed primarily to the much stronger lipid polar headgroup interactions characteristic of the former system. Finally, the considerable differences observed in the behavior of (LA)(12) and the related polyleucine-based peptide P(24) in both PC and PE bilayers indicate that the structure of the hydrophobic core of alpha-helical transmembrane peptides can affect their conformational plasticity and state of aggregation and thus the nature of their interactions with different phospholipid bilayers.

Alanine↗

PubMed1990

Comparison of indices of ambient exposure to 60-hertz electric and magnetic fields.

Occupational, environmental, or domestic exposure of human beings to extremely low-frequency (50- or 60-Hz) electric and magnetic fields varies continuously over time. In epidemiological studies of possible health effects, exposures over long durations must be aggregated in terms of simple summary indices. However, there are many different, biologically plausible, ways of aggregating the data. While awake, each of 20 electric utility personnel and 16 office workers had provided minute-by-minute measures of incident electric (V/m) and magnetic (muT) fields over a 7-day period via personal dosimeters. Once the measures were aggregated as means, medians, peaks, and other indices, intercorrelations between all index pairs were calculated; correlation matrices are presented for the utility and office workers both by group and when pooled. Product-moment coefficients (r) greater that .80 were found between the time-weighted arithmetic mean (TWA) and indices that explicitly emphasize short but highly intense exposures, such as peak values and time above thresholds. Medians and geometric means were less highly correlated with the TWA. Use of only a few indices, perhaps the TWA alone, may sacrifice but little statistical power in most epidemiological studies of utility workers exposed to ELF fields. However, correlations between electric-field strength and magnetic-field density were generally quite weak, as were correlations of either with high-frequency transients; these findings underscore the need to measure each of these variables in epidemiological studies. Indices of exposure incurred outside the workplace were less strongly correlated, which may indicate the need to use several indices in general-population studies.

Electromagnetic Fields↗

PubMed2002

Sponge versus diaphragm for contraception.

BACKGROUND: The contraceptive vaginal sponge was developed as an alternative to the contraceptive diaphragm. The sponge, made of polyurethane impregnated with nonoxynol-9 (1g), releases 125 mg of the spermicide over 24 h of use. Unlike the diaphragm, the sponge can be used for more than one coital act within 24 h without the insertion of additional spermicide, and the sponge does not require fitting or a prescription from a physician. How the sponge compares with the diaphragm in terms of efficacy and continuation is not clear. OBJECTIVES: To compare the efficacy and continuation rates of the sponge compared with the diaphragm (used with nonoxynol-9 as a spermicide). Our a priori hypothesis was that the sponge would have a higher failure rate and higher discontinuation rates than the diaphragm. SEARCH STRATEGY: We searched the computerized databases MEDLINE, EMBASE, Popline, LILACS, and the Cochrane Controlled Trials Register. In addition, we searched the reference lists of all potentially relevant articles and book chapters. We also contacted investigators involved with both trials identified to seek other published or unpublished trials. SELECTION CRITERIA: We included randomized controlled trials comparing the vaginal contraceptive sponge (Today; Collatex) with any diaphragm used with nonoxynol-9 to prevent pregnancy. DATA COLLECTION AND ANALYSIS: We examined the studies identified through the literature searches for possible inclusion and evaluated their methodological quality using the Cochrane guidelines. We contacted an author involved with both published trials for supplementary information about randomization and allocation concealment. We entered data into RevMan 4.1 and calculated Peto odds ratios for overall pregnancy and 12-month discontinuation using numbers of women as the denominator. We also abstracted 12-month cumulative life-table ratios for these same outcomes, but were unable to aggregate these data. MAIN RESULTS: The sponge was statistically significantly less effective in both trials in preventing overall pregnancy than was the diaphragm. The 12-month cumulative life-table termination rates per 100 women for overall pregnancy were 17.4 for the sponge versus 12.8 for the diaphragm in the larger U.S. trial and 24.5 for the sponge and 10.9 for the diaphragm in the U.K. trial. Similarly, discontinuation rates at 12 months were higher with the sponge than with the diaphragm (odds ratio 1.3; 95% CI 1.1-1.6). Allergic-type reactions were more common with the sponge in both trials, although the frequency of discontinuation for discomfort differed in the two trials. REVIEWER'S CONCLUSIONS: The sponge was less effective than the diaphragm in preventing pregnancy. Discontinuation rates were higher at 12 months as well. Other randomized controlled trials will be needed to resolve the role of spermicides in preventing sexually transmitted infections or in causing adverse effects.

Contraceptive Devices, Female↗

PubMed2005

The application of prescribing indicators to a primary care prescription database in Ireland.

OBJECTIVE: To develop appropriate prescribing indicators and apply these to Irish prescription data. METHODS: A postal survey of 145 randomly selected general practitioners working within the Eastern Health Board region of the State-supported General Medical Services scheme in Ireland regarding the applicability of selected prescribing indicators was carried out. Such indicators were then applied to aggregate prescription data. RESULTS: Prescribing indicators based on agents of questionable efficacy/poor quality prescribing and those based on good prescribing practice were thought to make suitable indicators. Low rates of prescribing were noted for indicators based on drugs of limited efficacy, e.g. cerebral and peripheral vasodilators (rate 3.1 per 1,000 prescriptions), whilst indicators based on drugs associated with good prescribing practice were associated with higher prescribing rates, e.g. the prescription of aspirin in patients receiving nitrate therapy(rate 7.13 per 1,000 patients). However, a low rate of generic prescribing (4.6%) was found amongst general practitioners in the study. The largest variability in prescribing was seen with the prescribing of peripheral and cerebral vasodilators (75th/25th centile=5.6) and the prescription of long-acting sulphonylureas (75th/25th centile=66.6). CONCLUSIONS: Quality indicators based on aggregate prescribing provide valuable information on prescribing standards and should be developed with the close involvement of prescribers.

Databases, Factual↗

PubMed2006

Airborne fungal spores in a cross-sectional study of office buildings.

Airborne fungal spores were measured in 44 office buildings in the summer and winter throughout the continental United States, as part of the Building Assessment, Survey and Evaluation (BASE) program. Six indoor air and two outdoor air samples were collected on a single day from each building. The cross-sectional and repeated measure design afforded evaluation of between-building and within-building variability of fungal spore levels in buildings. Total fungal spore concentrations in indoor air ranged from < 24 to 1000 spores/m3, except for one building with natural ventilation where indoor levels were approximately 9000 spores/m3. Indoor air concentrations of total spores did not vary significantly between winter and summer or morning and afternoon monitoring periods or among climate zones or locations within a test area. Indoor-outdoor ratios of total spore concentrations typically ranged between 0.01 and 0.1 and were approximately seven times greater in winter than summer because of relatively low outdoor levels in the winter. The indoor-outdoor ratio of total spore concentrations for a building was consistent (reliability coefficient = 0.91) among repeated measures. Distributions of rank correlation coefficients for spore types in pairs of individual indoor-outdoor and indoor-indoor samples were weakly correlated (Spearman correlation = 0.2 on average). When spore type data were aggregated among samples from the same building, the central tendency of the rank correlation coefficients increased to 0.45. Rank correlation coefficients were also proportional to the number of spore types present in the samples that were compared. The BASE study provides normative data on concentrations of fungal spores that can aid in identification of problematic levels of mold in buildings.

Air Microbiology↗

PubMed1997

Minimize risk and costly adverse events with data gathering, reporting program.

Benchmarking errors and adverse events: Studies show adverse events affect up to 35% of all patients, add up to 15% to each hospital's bottom line, and cost the country billions in health care dollars. But you can measure how often and where these events are occurring--and begin making improvements. Here's how to track incidents, aggregate the data, and use it to benchmark against other facilities and pinpoint improvement efforts-plus, sample reports from two hospitals.

Benchmarking↗

PubMed1996

Effect of the PAF-receptor antagonist SM-12502 on human platelets.

We analyzed the effect of the PAF receptor antagonist (+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one hydrochloride (SM-12502) on human platelet aggregation as well as mediator release. After incubation of human platelet with different concentrations of SM-12502 the cells were subsequently stimulated with either the Ca ionophore A23187, with human thrombin, or with an activator of heterotrimeric G-proteins, sodium fluoride (NaF, in the presence of Al3+). Preincubation of platelets with the PAF receptor antagonist led to an inhibition of 12-lipoxygenase derived 12(S)-HETE and cyclooxygenase derived 12(S)-HHT. Pretreatment of platelets with the PAF receptor antagonist SM-12502 prior to activation with the Ca ionophore A23187 or PAF also inhibited platelet aggregation. Our data clearly indicate an inhibitory effect of the new PAF receptor antagonist SM-12502 on the formation of platelet derived inflammatory mediators of the lipoxygenase pathway as well as of the cyclooxygenase pathway, and furtherone, treatment with the PAF receptor antagonist diminished platelet aggregation after subsequent specific and unspecific activation.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed2003

Outreach, mental health, and case management services: can they help to retain HIV-positive and at-risk youth and young adults in care?

OBJECTIVES: To assess the impact of outreach, mental health, and case management services on retention in primary care of HIV+ and at-risk youth and young adult clients of the Boston HAPPENS program, a comprehensive adolescent HIV prevention and care network of agencies. METHODS: Providers at 8 urban sites used standard data forms at each visit to collect background and service receipt information on at-risk clients aged 12-24 years. Data were aggregated across all visits for each client to create summary variables for the number of times each client received each type of service. The retention measure was the number of days between a client's first and last visits during the 4-year data collection period. Kaplan-Meier survival curve and Cox proportional hazards regression analyses were used to assess the association between receipt of the support services of interest and the retention measure. RESULTS: The median retention times were 21 days for male clients (range, 0-1406, N = 512), and 26 days for female clients (range, 0-1577, N = 914). Among males, 45% were retained beyond a month, 24% beyond a year, and 10% beyond 2 years. Similar proportions of females were retained beyond a month and a year, but more females were retained beyond 2 years (15%). After adjusting for other covariates, both male and female clients had significantly longer retention times if they received > or = 2 outreach contacts, or case management at > or = 3 visits. Among males, receipt of mental health counseling at > or = 2 visits also increased retention times. CONCLUSIONS: These findings suggest that provision of outreach, mental health, and case management services can improve retention in care of at-risk youth and young adults.

Adolescent↗

PubMed2006

Rheological properties of blood and parameters of platelets aggregation in arterial hypertension.

The results of some researches specify the important role of blood rheological properties changes in arterial hypertension (AH) pathogenesis. The goal of our study is to investigate the parameters of hemorheology and platelet aggregation in patients with various grade of AH. The study was carried out on 27 patients with grade 1 AH (group 1), 24 patients with grade 2 AH (group 2) and 29 healthy subjects (group 3). In patients of these groups, we evaluated erythrocytes deformability, red blood cells and platelets aggregation, blood and plasma viscosity. Using intra-vital computer-associated microscopic system we investigated microcirculation of bulbar conjunctiva. We observed that the rate of ADP-induced platelets aggregation is higher in group 1 as compared to groups 2 and 3. In groups 1 and 3, red blood cells rigidity index is significantly lower as compared to group 2. Erythrocyte aggregability is higher in group 2 in comparison with groups 1 and 3. The results obtained demonstrate that mild hypertension is associated with the rise of platelets aggregability, moderate hypertension is accompanied by the reduction of red blood cells deformability and increase of erythrocyte aggregability. These data may reflect differences in conditions for the formation of microcirculation disorders in AH of various grade.

Adult↗

PubMed1983

How much can business expect to profit from smoking cessation?

The data reviewed in this article, drawn from well-known, published sources; offer an estimate of the annual costs of smoking to the average employer. These costs range from +336 to +601 in January 1980 dollars per average smoking employee. The analysis is largely based on aggregate epidemiological data and, in general, the emphasis is on the under-estimating of the costs to business. It reports "averages" true for large populations and, therefore, is not individually predictive. The cost centers dealt with are insurance, medical, and others such as absenteeism, productivity, involuntary smoking, and occupational health risk. Included is a discussion of employer-sponsored smoking cessation programs and the benefits therefrom.

Absenteeism↗

PubMed1993

Thrombospondin as an agglutinin of platelets.

To study a hypothesis that thrombospondin (TSP) might function as an agglutinin in platelet aggregation, we designed two experiments. First, we prepared fibrinogen-coated agarose beads (fbg-beads) as a model of platelets, and subjected them to aggregometry using TSP as an inducer. TSP induced agglutination of fbg-beads in a dose-dependent manner. Calcium (Ca) and Magnesium (Mg) were necessary for the agglutination, and the aggregability was dependent on the concentration of Ca. These results confirmed the function of TSP as an agglutinin, suggesting some characteristics of the fbg-TSP interaction as well. Secondly, a variety of platelets were subjected to TSP-induced aggregation assay. Both gel-filtrated and washed-platelets were aggregated by TSP in a dose dependent manner and dissociated with EDTA. The same aggregation was observed in formalin-fixed platelets. Both Ca and Mg were required for the aggregation, and the maximum aggregation rate was dependent on the Ca concentration. Ca seemed to regulate the capacity as well as the affinity of the binding sites for TSP on platelets. Fibrinogen and some aminosugars inhibited the aggregation. These data suggest TSP may function as an agglutinin of platelets, and Ca may regulate the interaction between platelets and TSP. As one of the candidates for the receptor for TSP on platelet, fbg-GPIIb/IIIa was suggested because of the similarity between fbg-beads and platelets aggregation induced by TSP, and the Ca-dependency in both the GPIIb/IIIa induction and the TSP-induced platelet aggregation.

Agglutinins↗