Specific statistical considerations relevantto the design and analysis of gingivitis trials demonstrating

Simulation studies were conducted to address specific statistical issues which arise in the design and analysis of gingivitis studies whose principal aim is the demonstration of superiority or equivalence of one product to another. The effects of measurement scale, using differences or ratios of group means, particular statistical test produces and specific rules demonstrating superiority or equivalence were investigated. An alternative concept to equivalence—denoted “least as good”—was also defined and evaluated. For a wide class of possible distributions of gingivitis scores, characterized by specific gamma distributions, the student-t test applied to means of subject GI gingivitis scores proved to be the most powerful of the test produces considered, having statistical properties quite similar to the randomization or permutation test procedure. Transformations of subject GI mean gingivitis scores did not produce an advantage in demonstrating either superiority or equivalence, and in some cases made it more difficult. Little difference was observed in test results when using the difference in group means as compared with using the ratio of group means for demonstrating either equivalence or superiority. The clinically significant rule produced the lowest false-positive rates for products slightly better than the active control, and similar false-positive and -negative rates as the statistically significant rule for products clearly superior to the active control. Demonstration of product equivalence will require more subjects per group than demonstrating product superiority, the size of this difference being a function of the definition of superiority that is accepted. Showing that the 90% confidence interval for 100*R is completely contained within the [90%, 110%] interval is the preferred method of demonstrating equivalence today, although much more research needs to be done to improve methods for demonstrating product equivalence. The “least as good” alternative to “equivalence” makes it easier to demonstrate “equivalence” for products slightly better than the active control product, but both experience great difficulty in demonstrating equivalence for lest products not quite as good as the active control.     

Sequences in the proximal 5′ flanking region of the rat neuron-specific enolase (NSE) gene are sufficient for cell type-specific reporter gene expression

We investigated the regulation of the rat neuron-specific enolase gene using a transient transfection approach. Recent transgenic mouse studies have shown that a 1.8-kb segment of the ratNSE gene 5′ flanking region, including the first (noncoding) exon but not the first intron, is able to drive expression of a reporter gene in parallel with endogenousNSE. These data suggest thatcis-acting elements responsible for the spatial and temporal pattern ofNSE gene expression are located within the proximal 1.8 kb of the 5′ flanking sequence. To further investigate this region, we joined the 1.8-kb regulatory cassette to thecat reporter gene and generated a number of constructs in which the flanking sequence was progressively deleted from the 5′ end. These constructs were tested by transient transfection into neuronal and nonneuronal cells, followed by an assay for CAT activity. We found that as little as 255 bp of 5′ flanking sequence was able to confer cell type-specificity on the reporter gene. Further truncation to 120 bp of 5′ sequence resulted in a sharp downregulation of reporter activity in PC12 cells but a significant rise in both Neuro-2A neuroblastoma cells and nonneuronal Ltk- cells, indicating thatcis-acting elements controlling the regulation ofNSE in Ltk-, Neuro-2A, and PC12 cells may lie within the 135 bp region covered by this deletion. This region contains an AP-2 site and an element similar in sequence and position to a motif identified in the proximal promoter region of the neuron-specific peripherin gene. Reduction to 95 bp of 5′ sequence resulted in a slight downregulation of CAT activity in all cell lines tested, and further truncation to 65 bp of 5′ sequence caused a universal reduction to background levels of CAT activity, concomitant with the disruption of the basalNSE promoter. Our results show that the 5′ flanking region of theNSE gene is capable of conferring cell type-specificity on a heterologous gene in transfected cells and that elements responsible for this are located within the proximal 255 bp.     

A method for calculating the mean absorption time of drugs undergoing reversible and first-pass metabolism

A method has been derived for calculating the mean absorption time of an oral drug and its interconversion metabolite which is generated from the drug systemically and presystemically. The method evolves from the convolution integral and requires plasma AUC and AUMC values after separate intravenous administration of the drug and its interconversion metabolite and oral administration of the drug. It can also be used to calculate the mean input time of a drug undergoing reversible metabolism and administered by any other extravascular route. Results of a simulation study using both errorless and errant data indicate that, when the absorption rate constant of a drug or its interconversion metabolite is not much larger than the apparent elimination rate constant, the proposed method performs satisfactorily. However, when the absorption rate constant of a drug or its interconversion metabolite is much larger than the apparent elimination rate constant, the proposed method appears to be inaccurate.     

Measurement of upper extremity orientation by video stereometry system

In the attempt to gain a broader understanding of the causal relationships behind work-related symptoms of pain in the human shoulder, monitoring of arm position is crucial. Different methods have been used with varying accuracy. A video-based stereometry system, using infra-red light and reflecting markers for motion analysis, has been introduced for measurements in the fields of ergonomics, biomechanics and sports medicine. The purpose of this study is to investigate the sources of error in using this system for posture registration of the upper limb. Measurements are performed on a calibration fixture, on a mechanical model of the upper limb and on a subject with an exoskeleton. Particular, attention is given to inconsistencies and relative errors due to the finite geometrical precision with which the markers are positioned in the calibration fixture and on the studied objects, the limited capability to align the objects relative to the coordinate system of the calibration fixture and the errors connected to angular measurements using protractors etc. It is concluded that the system makes a valuable addition to existing instruments for non-contact posture measurement, and produces position data with an adequate accuracy in normal handling.     

微机判断血气的程序设计和临床应用

将肺心病、慢性肾炎等338例次的血气分析结果输入计算机,应用我们设计的多结果血气判断微机程序判断酸碱紊乱状态,其结果与人工综合判断结果完全相符。而单结果计算机判断和单纯人工判断的结果与人工综合判断结果的符合率分别为88.2％和87.3％。表明多结果计算机判断程序能有效地避免误判、漏判。     

Identifying target segments of male drinkers for health promotion

Data from a 1988 national drinking survey was cluster analysedto identify different types of male drinkers, to assist in thetargeting of health promotion strategies. Of the five segmentsgenerated by the clustering, one labelled Young Heavy DrinkingMales was identified as the most appropriate target segment,because although they were the segment reporting the highestlevel of alcohol-related problems they were also the segmentmost likely to feel they were drinking too much They were thereforethe segment most likely to be responsive to advertising thatsought to support people who wanted to change their drinkinghabits. They were also the most appropriate target for the longer-termgoal of changing the climate of opinion regarding the acceptabilityof more moderate drinking. Comparisons with two previous clusteranalyses showed a high degree of similarity, suggesting thatclustering is a reliable vehicle for identifying drinker types.     

羊水细胞培养宫内诊断的应用(附120例分析)

报告120例羊膜腔穿刺羊水细胞培养结果:在成功的99例中,发现二例染色体异常,核型为47,xy,+18和46,xx/47,xx,+F,在21例失败中出现一例眼球畸形。培养成功率为82.5%;染色体异常检出率为2.02%。无一例因羊膜腔穿刺而导致流产,但出现一例轻度羊水栓塞合并症。并对羊水细胞培养在产前宫内诊断中应用价值及术后并发症进行了讨论。     

Airborne emissions at skin surfaces: a potential biological exposure index

 Dermal exposures of methanol were administered in a clinical study designed to compare several biological indicators. Four subjects were exposed in five exposure sessions of varying length. In each session, a sequence of measurements of methanol concentrations in blood, breath, and headspace samples of air at exposed and unexposed skin were collected before and after dermal exposures. Skin headspace samples, collected in gas sampling bags, were designed to reflect equilibrium skin: air partitioning. At exposed skin, headspace samples were highly elevated for at least 8 h following exposure, indicating the presence of a methanol reservoir in skin. After exposure, methanol concentrations at exposed skin showed a rapid initial decline, then a slower first-order decrease. Methanol concentrations were clearly detectable in headspace samples at unexposed skin. Substantial transfer from exposed skin occurred due to mechanical contact and washing. When transfer was restricted, surface concentrations at unexposed skin were similar to levels in breath and were strongly correlated to methanol concentrations in blood. While results are preliminary due to the small sample sizes and several unresolved experimental issues, the simple, rapid, and noninvasive skin headspace measurements appear useful as a biological exposure indicator that clearly shows the presence and site of a dermal exposure, and measurements at unexposed skin reflect concentrations in blood. Received: 14 March 1995/Accepted: 3 November 1995     

A newly recognized point mutation in the cytochrome b558 heavy chain gene replacing alanine57 by glutamic acid,in a patient with cytochrome b positive X-linked chronic granulomatous disease

Molecular genetic analysis was performed in a patient with cytochrome b positive X-linked chronic granulomatous disease. A previous Southern blot study, using a cytochrome b heavy chain cDNA as probe, revealed a Pst I restriction fragment pattern for the cytochrome b heavy chain gene (CYBB) different to that of normal individuals. Since restriction length polymorphism with Pst I has never been observed in control individuals and no abnormal restriction fragment patterns in the patient's CYBB was detected with seven other enzymes used, we focussed on the single Pst I site in the CYBB cDNA as being the only mutation site responsible for his disease. A fragment of the patient's cDNA which included the Pst I site was amplified by reverse polymerase chain reaction, and loss of the Pst I site in the fragment was confirmed by incubation with Pst I. Subsequent sequence analysis of the fragment revealed a point mutation in the Pst I site (cytosine to adenine), substituting glutamic acid for alanine at position 57.     

Mothers' discrimination of their neonates' cry in relation to cry acoustics: The first week of life

This study investigated the temporal evolution in the discrimination of the newborn's crying by the mother, from the first to the eighth day after birth. The sample included twenty human mothers who had had an uneventful pregnancy, labour and delivery. They were asked to identify the spontaneous cries of their newborn babies from tape-recorded cries containing cries from their own newborn and from three other newborns. On the first day, the percentage of correct answers was 48#pc, then 81 #pc on the eighth day. Two acoustic features that may underlie this discrimination were analyzed: the maximum Fo values and the average number of cry bursts per second. On the seventh day, these two acoustic variables and the discrimination abilities significantly correlate.