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PubMed2000

Estimation of number of subjects required for comparison of drug versus control in adaptive designs.

INTRODUCTION: Adaptive designs have often been proposed as a way of using accruing data to affect future allocation scheme in clinical trials. The goal is to assign more patients to the better treatment. To implement clinical trials efficiently, sample size must be estimated in advance. In adaptive design, it is difficult to calculate the required sample size, because the allocation probabilities keep changing during the course of the trials. METHODS: We focus on the sample size of two-arm (drug versus control) clinical trials. Based on its asymptotic properties, a formula of calculating sample size is derived for the randomised play-the-winner rule. We also compare sample size and power between the randomised play-the-winner rule and equal allocation. Some simulation studies illustrate the operating characteristics of the designs. RESULTS AND DISCUSSION: The required sample size of the randomised play-the-winner rule is slightly larger than that of the equal allocation design in most cases. The randomised play-the-winner rule is recommended for ethical reasons.

Clinical Trials as Topic↗

PubMedDate not supplied

Use of the granulosa cell aromatase bioassay for measurement of bioactive follicle-stimulating hormone in urine and serum samples of diverse species.

Ovarian steroids and growth factors are intragonadal modulators which augment a key endpoint of follicle-stimulating hormone (FSH) action in granulosa cells: the induction of aromatase activity. Studies of these paracrine hormones that enhance FSH-stimulated estrogen biosynthesis by cultured rat granulosa cells, have led to the development of a sensitive and specific in vitro bioassay for FSH. This newly developed granulosa cell aromatase bioassay (GAB) allows for the measurement of bioactive FSH levels in serum and urine of humans and animals with various physiological and pathological conditions. These studies have demonstrated that the GAB assay is useful in detecting possible changes in the molecular forms of FSH. The adaptation of this method for urine samples allows for the measurement of bio-FSH levels in situations where venipuncture is not practical or in species for which specific radioimmunoassays are not available.

Animals↗

PubMed1998

Immunoenzymatic determination of atrazine in rat tissue samples.

In the present study our objective was to adapt a competitive enzyme immunoassay (EIA) for the determination of atrazine in animal tissues (liver and kidney). Female Wistar rats were administered through gavage with a single dose of atrazine (500 or 1000 mg/kg body weight) and sacrificed 24, 48 h and 7 days following the exposure. Using liver tissue samples the extraction procedure was improved. The atrazine concentrations measured in the liver were higher than those found in the kidney, but both can be ranked as low compared with the amount of the administered doses. These data confirm that tissue retention is minimal. Further studies are necessary in order to make an overall evaluation concerning the amount of atrazine retained in the organism. We consider that the competitive EIA may be a promising technique for epidemiological screening of pesticides.

Administration, Oral↗

PubMed1999

Fluctuating life-history parameters indicating temporal variability in metal adaptation in riverine chironomids

Adaptation to toxicants in animal populations is influenced primarily by two counteracting forces. First, the intensity and duration of peak concentrations of toxicants is responsible for the actual level of selection pressure on the population. Second, the process of adaptation can be disrupted by gene flow as a result of crossings with nontolerant individuals. These counteracting forces were analyzed in riverine insects in which we expected that the level of metal adaptation is subject of considerable fluctuations, due to variable dilution of metals and a variable transport of nontolerant individuals in river water. To this purpose, the stability of metal adaptation in different Chironomus riparius populations was analyzed during a 5-month period in a heavily polluted lowland river. This was examined by measuring mortality, larval dry weight, and accumulation of zinc under laboratory conditions. The results showed that in midge populations originating from metal-contaminated field sites several life-history parameters (like control mortality and growth response under cadmium exposure) of the laboratory reared F1 generations showed considerable temporal variation. In addition, the presence of metal-adapted midge populations was indicated on several occasions on the metal-exposed field sites. Reference populations on the other hand, showed stable life history patterns throughout the sampling period, and no signs of metal adaptation were found. These observations showed that the actual level of metal adaptation varies considerably, both in time and space. Adaptation to metals in riverine chironomids, therefore, should be looked on as a highly dynamic process.http://link. springer-ny.com/link/service/journals/00244/bibs/37n2p175.html

Journal Article↗

PubMed1999

Fast and reliable screening of mutations in human tumors: use of multiple fluorescence-based long linker arm nucleotides assay (mf-LLA).

Human tumor samples were screened for point mutations by adapting a mobility-shift assay to automated DNA sizing. This screen identifies the type of point mutation and relative amount of mutated DNA sequences present in a sample. Test samples having known hypoxanthine-guanine phosphoribosyl transferase (hprt)/exon-3 sequence mutations were characterized by: (i) PCR amplification, (ii) fluorescent dye-primer extension with 36-atom linker derived deoxycytosine or deoxyuridine triphosphate and the remaining three natural nucleotides and (iii) sizing of the resulting fluorescently labeled modified strands, using an automated DNA sequencer. Routinely, a range of sizes is observed among the sequence variants of a single DNA target sequence. This is because nucleotide analogs are incorporated into DNA strands in a sequence-dependent manner, resulting in composition-dependent electrophoretic mobility. Thus, point mutations are identified as shifts in mobility between the fluorescently labeled modified strands of the control and test samples. The twenty different hprt/exon-3 single-base substitution mutations tested were easily identified, even at fourfold dilution with control DNA.

Animals↗

PubMed1989

[Suitability of denture base by light-cured resin for reline].

With a view to evaluating the dimensional accuracy of the light-cured relining resin from the viewpoint of the suitability of the mucosal surface of the denture base, an experiment by direct relining technique was made using a total of 12 materials, i.e. 2 kinds of denture base material, 3 kinds of relining material and 2 kinds of denture base mold; cured, refined test sample interposed by impression material was adapted to the prototype and was measured for the thickness of impression material by means of stereoscopic microscope. The results obtained were as follows: 1) Lifting discrepancies averaged 0.5, 0.8 and 1.2mm for E (Eporex-E), R (Rebaron) and T (Triad), respectively, indicating a significant difference in lifting discrepancy according to the kind of relining materials. 2) In terms of the different molds of denture base, 2 kinds of R and E tended to show a little greater lifting discrepancies for thick samples of the alveolar ridge area, compared with the opposite tendency in case of T. 3) In terms of the different materials, combination of A and E (Acron.Eporex-E), and that of B and E (Triad.Eporex-E) showed values of the same order without difference. 4) Standard deviation for T showed a value of about 0.5mm or so, with a greater variation than others.

Acrylic Resins↗

PubMed1987

Estrogen and progestin receptor assay in fine needle aspirates of breast cancer: methodological aspects.

A methodology, originally built up in our laboratory, for the simultaneous determination of estrogen (ER) and progesterone (PR) receptors on small samples of tumor tissues, has been adapted to fine needle aspirates (FNA) of breast tumors. The method is based on a simultaneous incubation of aliquots of high-salt (0.4 M KCl) cytosols with tritiated estrogen and progestin tags. The mixture of receptor-bound ligands is isolated by dextran-coated charcoal and extracted by ethanol. The extracted ligands are separated quantitatively by HPLC and counted by liquid scintillation. FNA provides sufficient cellular material for ER and/or PR assay by single point (5 nM) dextran-coated charcoal (DCC) assay. FNA samples, being contaminated by blood, [3H] R 2858 and [3H] O 2058 are appropriate tags for ER and PR respectively, giving lowest non-specific binding. Sixty-five simultaneous estrogen and progestin receptor determinations on FNA at time of diagnosis were compared to the individual assays performed on the surgical sample obtained from the same patients a few weeks after diagnosis. The correlation between the 2 sets of determinations is excellent in 60 cases with sufficient FNA cellularity. This correlation validates the reliability of estrogen and progestin receptor determination on FNA in the majority of clinical cases.

Biopsy, Needle↗

PubMedDate not supplied

Adaptation of the bard prostate biopsy gun for CT-guided abdominal biopsies.

The Bard prostate biopsy gun under ultrasonic guidance provides consistent, high quality prostatic core samples for histopathologic diagnosis. This device can be adapted for biopsy of abdominal organs using computed tomographic guidance. We demonstrate how these technical modifications can be made. Having used this modified device in conjunction with the 18-gauge prostate biopsy needle in 25 patients, we have had excellent results and no complications.

Abdomen↗

PubMed2005

Reliability of the Social Phobia and Anxiety Inventory (SPAI) Portuguese version in a heterogeneous sample of Brazilian university students.

OBJECTIVE: To evaluate internal consistency and temporal stability trough test re-test reliability of the Portuguese version of the Social Phobia and Anxiety Inventory (SPAI) in a heterogeneous Brazilian sample. METHODS: After informed consent, the translated and adapted version of the SPAI Portuguese was tested and re-tested at a 14-day interval in a sample of 225 university students, both genders, from 4 different undergraduate courses. After double data entry, statistical analysis included Cronbach's alphas, Pearson and intra-class correlation coefficients. RESULTS: The studied sample consisted of 213 students from 4 sub-samples: 95 law students, 31 social communication students, 54 civil engineering students and 33 dental medicine students. The mean age was 23 (+/-6) years and 110 (51.6%) were female. The Cronbach' alpha was 0.96, no difference for both genders. The differential (total) score of the SPAI Portuguese showed Pearson coefficient 0.83 (95% CI 0.78-0.87) and Intra-class coefficient 0.83 (95% CI 0.78-0.86). There was no statistical difference in Pearson coefficients between genders (p = 0.121) and the 4 sub-samples (p = 0.258). CONCLUSION: The results do not ensure validity, however, the SPAI Portuguese version presented a good content homogeneity with satisfactory level of internal consistency. The temporal stability evaluated was substantial. The results showed that the Portuguese SPAI presents perfectly acceptable reliability for both genders and suggest that it can be used in Brazilian populations.

Adolescent↗

PubMed1998

Density estimates of rural dog populations and an assessment of marking methods during a rabies vaccination campaign in the Philippines.

We estimated the population density of dogs by distance sampling and assessed the potential utility of two marking methods for capture-mark-recapture applications following a mass canine rabies-vaccination campaign in Sorsogon Province, the Republic of the Philippines. Thirty villages selected to assess vaccine coverage and for dog surveys were visited 1 to 11 days after the vaccinating team. Measurements of the distance of dogs or groups of dogs from transect lines were obtained in 1088 instances (N = 1278 dogs; mean group size = 1.2). Various functions modelling the probability of detection were fitted to a truncated distribution of distances of dogs from transect lines. A hazard rate model provided the best fit and an overall estimate of dog-population density of 468/km2 (95% confidence interval, 359 to 611). At vaccination, most dogs were marked with either a paint stick or a black plastic collar. Overall, 34.8% of 2167 and 28.5% of 2115 dogs could be accurately identified as wearing a collar or showing a paint mark; 49.1% of the dogs had either mark. Increasing time interval between vaccination-team visit and dog survey and increasing distance from transect line were inversely associated with the probability of observing a paint mark. Probability of observing a collar was positively associated with increasing estimated density of the dog population in a given village and with animals not associated with a house. The data indicate that distance sampling is a relatively simple and adaptable method for estimating dog-population density and is not prone to problems associated with meeting some model assumptions inherent to mark-recapture estimators.

Animal Identification Systems↗

PubMed1996

Testing an uncertainty model for women with multiple sclerosis.

This study sought to explain adaptation to the uncertainty of multiple sclerosis (MS) in women. A casual model, developed from the literature and from interviews with four women with MS, was tested on a sample of 90 women with MS. Successful adaptation was measured by self-esteem and mastery. The model accounted for 26% of the variance in mastery, with an empirical model accounting for a higher degree of variance (41%). Findings suggest that the negative impact of uncertainty in women with MS is significantly reduced by their spiritual and social relationships.

Adaptation, Psychological↗

PubMed1999

[Acid-base status in newborn calves during the first days of life considering different states of vitality].

The aim of this study is to describe the differentiations of the acid-base status in bovine neonates during the first 96 hours of life. Due to the short intervals in the taking of blood samples, noticeable fluctuations in the acid-base status during the first minutes and hours of life of newborn calves were documented. Altogether, 25 matures and eutrophe calves of the DSB, DRB and DFV breeds were provided by the clinic for this study. Apart from an immediate post natum clinical interpretation of the vital signs in the neonates-using the APGAR-score-the pH value, current Base Excess and the CO2 pressure were simultaneously ascertained. Further continuous evaluation of the acid-base status was subsequently followed in the first phase of adaptation. For that alone, twelve blood samples were taken from the vena jugularis within the first 60 minutes after parturition. Until the end of the examination period on the fourth day of life, the tests amounted to 26 measurements altogether per experimentee. Due to the concrete results ascertained from the initial clinical and laboratory observations, the experimentees could be divided into distinct classes of vitality. The acid-base status of all the calves deteriorated during the first minutes of life, indicating that the pH value and Base Excess fall clearly under the initial level in all aspects of vitality directly post natum. On average the minimum pH values are reached between the third and 15th minute of life and remain between 0.019 and 0.096 below the initial values during this period. A varying rapid increase of the pH value follows, together with a balancing out of the Base difference. Despite isolated individual variations as the acid-base status develops, the lowering of the pH values in the first minutes of life is assessed as being a normal biological phenomenon. Deviations from this occur rarely (8%) and do not conform to the norm. The pH value stabilization in connection with this crucial early postnatal phase occurs to such a high degree that, without stagnation, on average all experimentees show pH values between 7,270 and 7,300 after 180 minutes of life-regardless of which vitality group they belong to. After reaching this common value at the end of the third hour of life, the further development of the ph values and the consequential resulting parameters in all three vitality groups are similar. A stagnation of the rising pH value between the 4th and 12th hour of life was established during the examination. Moderate stabilization then set in after this phase. Between the 24th and 36th hour of life all experimentees reached an average highest pH value of 7,400. Until the end of the examination period, however, this then dropped slightly to values between 7,380 and 7,395.

Acid-Base Equilibrium↗

PubMed1996

Detection of cytomegalovirus in blood donors by PCR using the digene SHARP signal system assay: effects of sample preparation and detection methodology.

Cytomegalovirus (CMV) is an important cause of transfusion-associated morbidity and mortality; however, only 0.4 to 12% of the blood products obtained from seropositive blood donors transmit infection. The effects of three commercially available whole-blood sample preparation kits on the detection of CMV PCR products by a semiquantitative adaptation of the Digene SHARP Signal System Assay (DSSSA) in samples from volunteer blood donors was assessed. Of 101 samples from seropositive blood donors, CMV was detected in 0 (0%) of the samples extracted with a QIAamp blood kit (QIAGEN), 1 (1%) of the samples extracted with an Amplicor whole-blood specimen preparation kit (Roche), and 8 (8%) of the samples extracted with an Isoquick nucleic acid extraction kit (modified by the addition of carrier tRNA) (Microprobe). CMV DNA was not detected in samples from seronegative blood donors (n = 13). Nested PCR of selected samples confirmed the detection of CMV in the sane eight samples extracted with the modified Isoquick nucleic acid extraction kit and detected an additional nine CMV-positive samples (n = 50). Samples from volunteer blood donors contain low copy numbers of CMV DNA. PCR amplification of such specimens can result in analytical sampling errors, giving results similar to the variations in titers recognized during determinations of the 50% tissue culture infective dose. The detection of CMV in blood samples from volunteer blood donors by PCR is a function of sample preparation, amplification conditions, and detection methodology. Accurate assessments of the clinical utility of CMV DNA detection by nucleic acid amplification for blood product screening and patients will require highly standardized and quantitative methodology.

Blood Donors↗

PubMed1993

Extended multipoint identity-by-descent analysis of human quantitative traits: efficiency, power, and modeling considerations.

Goldgar introduced a novel marker-based method for partitioning the variation of a quantitative trait into specific chromosomal regions. Unlike traditional linkage mapping methods, Goldgar's method does not require the estimation of statistical quantities characterizing each locus thought to influence the trait under scrutiny (e.g., allele frequencies, penetrances, etc.). Goldgar's method is thus more flexible and less model dependent than many traditional marker-based genetic analysis techniques. Unfortunately, however, many of the properties of Goldgar's method have not been investigated. In this paper, the utility of an extended version of Goldgar's approach is studied in settings in which sibships are taken as the sampling unit of interest. The extensions discussed resolve around the incorporation of a wider variety of effects and factors into Goldgar's basic model. Analytic studies pertaining to power, sample-size requirements, and estimation procedures for the proposed extended version of Goldgar's method are described. Hypothesis-testing strategies are also discussed. The results of the analytic studies indicate that, although an extended sib-pair version of Goldgar's variance-partitioning approach to modeling the chromosomal determinants of a quantitative trait will be useful only for traits with high heritabilities or when fine-scale genetic maps can be employed. Goldgar's technique as a whole has promise, as it can be made relatively robust statistically, refined through some simple and intuitive extensions, and can be easily adapted to work with more complex sampling units. Further extensions of Goldgar's methods are proposed, and areas in need of additional research are discussed.

Genetic Markers↗

PubMed1996

Adaptation to community relocation: the interactive influence of psychological resources and contextual factors.

This longitudinal study examined the interactive influences of psychological resources and contextual factors on short-term adaptation to community relocation in a sample of older women (N = 102, mean age = 71.6). The effects of three psychological resources (environmental mastery, autonomy, and personal growth) and three contextual factors (pressure to move, difficulty of the move, and unexpected gains experienced) on emotional reactions to relocation were examined. The pattern of findings suggests that women with greater psychological resources were more resilient in the face of negative circumstances but that the emotional "boost" of unexpected gains was greatest for women with lower premove resources. These results underscore the importance of considering event-relevant psychological resources and contextual factors and including both negative and positive aspects of the adaptational process.

Adaptation, Psychological↗

PubMed2000

Complete denture wearers: electromyography of mastication and texture perception whilst eating meat.

This study was undertaken to evaluate the sensitivity of denture wearers to different food textures and to follow masticatory pattern adaptation with variation in texture using electromyography (EMG) recordings. Nine patients with complete dentures and 9 dentate control patients without any oro-dental pathology were studied. Six different samples of beef were obtained from the same muscle by altering the state of the muscle fibres and by variation of the cooking temperature. The variations in texture were mechanically controlled. Electromyographic activity was recorded during chewing. The patients' subjective appreciation of texture was reported using a 10-cm non-structured analogue scale. The following parameters were analysed: muscle work, number of masticatory cycles, number of rejected samples, initial tenderness, overall tenderness, juiciness, and duration of chewing for each sample in the mouth. Muscle activity was less for the edentulous group, particularly that of the masseter muscles. The masticatory pattern of complete denture wearers was less adapted to each sample texture than was that of the control group. Both groups perceived differences in texture of the samples. It was concluded that although texture perception is little altered, muscular adaptation to the bolus is reduced in patients with complete dentures.

Adaptation, Physiological↗

PubMed2000

Development of a rapid PCR assay specific for Staphylococcus saprophyticus and application to direct detection from urine samples.

Staphylococcus saprophyticus is one of the most frequently encountered microorganisms associated with acute urinary tract infections (UTIs) in young, sexually active female outpatients. Conventional identification methods based on biochemical characteristics can efficiently identify S. saprophyticus, but the rapidities of these methods need to be improved. Rapid and direct identification of this bacterium from urine samples would be useful to improve time required for the diagnosis of S. saprophyticus infections in the clinical microbiology laboratory. We have developed a PCR-based assay for the specific detection of S. saprophyticus. An arbitrarily primed PCR amplification product of 380 bp specific for S. saprophyticus was sequenced and used to design a set of S. saprophyticus-specific PCR amplification primers. The PCR assay was specific for S. saprophyticus when tested with DNA from 49 gram-positive and 31 gram-negative bacterial species. This assay was also able to amplify efficiently DNA from all 60 strains of S. saprophyticus from various origins tested. This assay was adapted for direct detection from urine samples. The sensitivity levels achieved with urine samples was 19 CFU with 30 cycles of amplification and 0.5 CFU with 40 cycles of amplification. This PCR assay for the specific detection of S. saprophyticus is simple and rapid (approximately 90 min, including the time for urine specimen preparation).

DNA, Bacterial↗

PubMed2005

Pyrosequencing in a microfluidic flow-through device.

To explore genome variation meaningfully, there is a critical need for a high-throughput and inexpensive platform for DNA analysis. Pyrosequencing is a nonelectrophoretic bioluminometric DNA sequencing method that uses a four-enzyme mixture reaction to monitor nucleotide incorporation in real time. Currently, the commercialized pyrosequencing technique is limited to a 96-microtiter plate format. However, high throughput and inexpensive pyrosequencing is required to meet the need of screening large numbers of samples. We present here DNA pyrosequencing on a nanoliter-volume microfluidic platform. The microfluidic approach involves the trapping of the DNA on microbeads in an on-chip filter chamber and flow-through of the pyrosequencing reagents to monitor the reaction in real time. Two single-nucleotide polymorphisms were successfully scored to evaluate the microfluidic platform. In addition to significantly reducing reagent costs, microfluidic systems promise to improve the read length by eliminating intermediate product accumulation by constant removal of unincorporated nucleotides and elimination of dilution effects at each reaction cycle in the current plate format. Although only one filter chamber was used in this study, the platform should be readily adaptable to parallel analyses of nanoliter samples using filter chamber arrays to obtain high-throughput DNA analysis.

Base Sequence↗