Aneuploidy among prenatally detected neural tube defects.

We have reported previously a 10% aneuploidy detection rate among 39 cases of fetal neural tube defects (NTD). Subsequently we amassed an additional experience of over 17,000 prenatal diagnosis cases over a 5-year period. During this period 106 cases of NTDs were identified; 44 with anencephaly, 62 with open spina bifida. The average maternal age of this population with NTDs was 29 years (15-40); 6 patients declined amniocentesis. Six of 100 cytogenetic studies were aneuploid; one anencephalic fetus had inherited a maternal marker chromosome, and 5 NTD cases had trisomy 18. The average maternal age of the aneuploid cases was 31 (19-40); 3 were 35 years or older. Four of 5 trisomy 18 cases had multiple congenital anomalies (MCA). The overall aneuploidy detection rate in our cohort was 5-6%, while aneuploidy occurred in 2% of the isolated NTD cases, and 24% of the MCA cases. Combining the earlier experience, 4/39 aneuploidy (2 trisomy 18, 4p+, del 13q) yields an aneuploidy detection frequency of 10/145 (7%), of which most (7/10) had trisomy 18. These data support fetal karyotyping for accurate diagnosis, prognosis, and recurrence-risk counseling.

Determinants of parental decisions after the prenatal diagnosis of Down syndrome.

We evaluated demographic factors and factors specific to the current pregnancy, and their relationship to the decision to continue or terminate a pregnancy after prenatal diagnosis of Down syndrome. All cases of Down syndrome (DS) managed at a tertiary care center from 1989-1997 were retrospectively analyzed with respect to maternal age, parity, gestational age, sonographic findings, insurance status, and race. Of 145 cases of trisomy 21, 19 (13.1%) of women chose continuation of pregnancy, while 126 (86.9%) chose termination. There were no differences between groups in parity, sonographic findings, insurance status, or race at the time of diagnosis. However, patients who chose termination were significantly older and earlier in gestation than those electing to continue their pregnancy. When Down syndrome is diagnosed prenatally, the choice of termination is related to maternal age and gestational age, but only gestational age is a significant independent predictor of pregnancy termination.

Neuropathologic findings in a case of OFDS type VI (Váradi syndrome).

Oral-facial-digital syndrome type VI (OFDS VI) or Váradi syndrome is a rare autosomal-recessive disorder distinguished from other oral-facial-digital syndromes by metacarpal abnormalities with central polydactyly and by cerebellar abnormalities. Histopathologic characterization of the cerebellar abnormalities has not been described previously. We describe the neuropathologic findings in a stillborn, 21-week estimated gestational age (EGA) male fetus diagnosed antenatally with signs of OFDS VI. Autopsy findings included: facial abnormalities, postaxial central polydactyly of the right hand, bilateral bifid toes, and absence of cerebellar vermis with hypoplasia of the hemispheric cortex. Microscopic analysis of the cerebellum demonstrated absence of the subpial granular cell layer and disruption or dysgenesis of the glial architecture. These histopathologic findings suggest that a primary neuronal or glial cell defect, rather than an associated Dandy-Walker malformation, may account for the cerebellar abnormalities in this form of oral-facial-digital syndrome.

Recollections of things schematic: room schemas revisited.

In 2 experiments, the authors examined the effects of schemas on the subjective experience of remembering. Participants entered a room that was set up to look like a graduate student's office under intentional or incidental learning conditions. They later took a recognition memory test that included making remember-know judgments. In Experiment 1, they were tested during the same session; in Experiment 2 they were tested either during the same session or after a 48-hr delay. Consistent with the authors' predictions, memory for atypical objects was especially likely to be experienced in the remember sense. In addition, false remember judgments rose dramatically after the 48-hr delay, especially for participants in the incidental learning condition. Results are discussed in terms of schema theory, fuzzy-trace theory, and the distinctiveness heuristic.

Source attributions and false memories: a test of the demand characteristics account.

When lists of related words are presented to subjects, they sometimes recall or recognize nonpresented words related to those lists (critical lures). In fact, subjects sometimes claim to remember which of two speakers said the critical lures. We examined whether this finding could be accounted for by demand characteristics. If subjects' willingness to make source attributions to critical lures reflects experimental demand, one would predict that subjects should be willing to change and should havelittle confidence in these attributions. Subjects made more attributions, were less likely to change their attributions, and were more confident in their attributions for critical lures than for unrelated distractors. Subjects had even more confidence in the attributions that they made for words that had actually been presented, and they were even less likely to change these attributions. These findings suggest that false memories are quite compelling but that they are also subtly different from true memories.

Patient specific doses used to analyse the optimum dose delivery in barium enema examinations.

The exposure and geometrical data for 89 barium enema examination patients were recorded manually in five hospitals in Finland. From the recorded data, organ and primary exit doses as well as effective individual doses were calculated for each patient using the ODS-60 program, which is capable of adjusting the calculation phantom according to a patient's size and sex. The mean (and standard deviation, SD) and median effective individual doses for the patients were 9.3 (5.7) and 6.8 mSv, respectively. Conversion functions from dose-area product to relevant organ doses and to effective individual dose were presented as a function of patient sex and weight. Mean primary exit dose values were calculated for each exposure. These were used to compare a theoretically justified exposure control (EC) function with the function of the automatic exposure (rate) control, AEC (AERC), at different hospitals. According to the analysis of primary exit doses, the implementation of the EC was far from optimum. With EC function proposed in this study the SD of effective individual doses to patients could be lowered considerably.

Computing patient doses of X-ray examinations using a patient size- and sex-adjustable phantom.

Both the use of traditional fluoroscopy and the increasing use of modern digital techniques in radiology and interventional radiology demand the development of versatile computer programs for patient dose determinations. Long computing times restrict the use of Monte Carlo (MC) methods in dose monitoring applications where the radiological views change frequently. In the Organ Doses Calculation Software application (ODS-60), the phantom model is similar in principle to the Alderson-Rando (A-R) phantom, but its sex, size and shape is modified according to a particular patient. Organ and effective doses are computed online (in a few seconds) using a method similar to the traditional dose planning systems used in radiotherapy. In this paper, the new ODS-60 software is presented in detail and its capabilities are demonstrated. Software performance was determined by comparing the results with those from independent methods. In the case of a reference man-sized male, the effective dose was about 7% larger than the effective dose given in another publication. In the case of a reference woman-sized female, the disagreement with the other method was greater (33%). Anatomical differences between the phantom models (ODS-60 and MC) were found to be the main reasons for these findings. This paper shows the advantage of using a patient size- and sex-adaptable phantom for patient dose determinations; the conversion coefficient from entrance surface dose-to-effective dose ratio between male (170 cm, 85 kg) and a female (160 cm, 43 kg) varies in the range 1.5-2.

Bayesian approach for neural networks--review and case studies.

We give a short review on the Bayesian approach for neural network learning and demonstrate the advantages of the approach in three real applications. We discuss the Bayesian approach with emphasis on the role of prior knowledge in Bayesian models and in classical error minimization approaches. The generalization capability of a statistical model, classical or Bayesian, is ultimately based on the prior assumptions. The Bayesian approach permits propagation of uncertainty in quantities which are unknown to other assumptions in the model, which may be more generally valid or easier to guess in the problem. The case problem studied in this paper include a regression, a classification, and an inverse problem. In the most thoroughly analyzed regression problem, the best models were those with less restrictive priors. This emphasizes the major advantage of the Bayesian approach, that we are not forced to guess attributes that are unknown, such as the number of degrees of freedom in the model, non-linearity of the model with respect to each input variable, or the exact form for the distribution of the model residuals.

Distortion tolerant pattern recognition based on self-organizing feature extraction.

A generic, modular, neural network-based feature extraction and pattern classification system is proposed for finding essentially two-dimensional objects or object parts from digital images in a distortion tolerant manner, The distortion tolerance is built up gradually by successive blocks in a pipeline architecture. The system consists of only feedforward neural networks, allowing efficient parallel implementation. The most time and data-consuming stage, learning the relevant features, is wholly unsupervised and can be made off-line. The consequent supervised stage where the object classes are learned is simple and fast. The feature extraction is based on distortion tolerant Gabor transformations, followed by minimum distortion clustering by multilayer self-organizing maps. Due to the unsupervised learning strategy, there is no need for preclassified training samples or other explicit selection for training patterns during the training, which allows a large amount of training material to be used at the early stages, A supervised, one-layer subspace network classifier on top of the feature extractor is used for object labeling. The system has been trained with natural images giving the relevant features, and human faces and their parts have been used as the object classes for testing. The current experiments indicate that the feature space has sufficient resolution power for a moderate number of classes with rather strong distortions.

Calculating internal dose by convolution from SPECT/MR fusion images.

A new computer program was developed to calculate the absorbed dose. The program is based on the use of the convolution method and abdominal SPECT/MR fusion images. The applicability of the method was demonstrated by using data from (111)In-labeled thrombocyte and 99mTc-labeled colloid studies of three healthy volunteers. Dose distributions in the volunteers and the average absorbed doses in liver and spleen were calculated. The average doses for 99mTc-labeled colloid study were 0.07 +/- 0.02 (liver) and 0.046 +/- 0.005 mGy/MBq (spleen). The results are in good agreement with a Monte Carlo (MC) based method (0.074 for liver and 0.077 mGy/MBq for spleen) used by the International Commission on Radiological Protection (ICRP). For (111)In-labeled thrombocyte study the doses were 0.33 +/- 0.05 (liver) and 8.9 +/- 1.2 mGy/MBq (spleen) versus 0.730 and 7.50, respectively. The differences in dose estimates in the (111)In-labeled thrombocyte study are mainly due to the approximation used in activity quantitation. Convolution of the activity distribution with a point dose kernel is an effective method for calculating absorbed dose distribution in a homogeneous media. Activity distribution must be aligned to anatomical data in order to utilize the calculated dose distribution. The program developed is applicable to and practical for clinical use provided that the input data needed are available.

The impersistence of false memory persistence.

When subjects study lists of thematically related words they sometimes falsely recognise non-presented words related to the theme. The gist extraction account of these findings provided by fuzzy trace theory suggests that false recognition should decline substantially more slowly than true recognition across a delay. In two experiments we demonstrated that corrected recognition of targets and critical lures can decrease by equivalent amounts across a 48-hour delay. However the results for uncorrected recognition were mixed. In Experiment 1 we found evidence that uncorrected recognition of targets declined more rapidly than uncorrected recognition of critical lures. In Experiment 2, we found evidence that uncorrected recognition of targets and critical lures declined at equivalent rates. Results are discussed in terms of their implications for fuzzy trace and source monitoring accounts of false memories.

Use of controlled luciferase expression to monitor chemicals affecting protein synthesis.

In this article, we present a new bioluminescent test system for the screening of chemical compounds with an inhibitory effect on protein synthesis. The test is based on the measurement of real-time in vivo light production by Escherichia coli strains expressing different luciferase genes. The eukaryotic lucGR gene from Pyrophorus plagiophthalamus was found to be the best of three types of luciferase genes tested. Chemicals with known inhibitory effects on protein synthesis were used as test chemicals together with some general toxicants. The incubation of a test chemical with cells was performed either prior to or after the induction of protein synthesis, and the difference in the results of the two methods distinguishes the possible influence on protein synthesis from direct metabolic inhibition. Using lyophilized bacteria, the test is performed in less than an hour without any bacterial cultivation, which makes the test suitable for rapid and sensitive screening of chemicals or environmental samples. Compared with the standardized 50% inhibitory concentration calculation method of the bioluminescent cytotoxicity test, the more direct approach of calculation developed in this study proved to be more convenient than and as reliable as the standard method.

Evaluation of Abbott TESTPACK ROTAVIRUS with clinical specimens.

TESTPACK ROTAVIRUS was compared with the Pathfinder Rotavirus assay for the detection of rotaviral antigens in feces from 137 patients. The symptomatology and ages of the patients varied from no symptoms to watery diarrhea and from less than 3 months to greater than 60 years of age. The sensitivity and specificity, before resolution, were 89.2 and 90.0%, respectively. After resolution with a blocking reagent, the results were 100% sensitivity and 98.9% specificity. The performance was similar for all age groups and in both symptomatic and asymptomatic patients. Abbott TESTPACK ROTAVIRUS is a rapid (10-min), easy-to-perform assay for the detection of rotaviral antigens and has the sensitivity and specificity of enzyme-linked immunosorbent assays that require several hours to perform.

Factors influencing patient radiation doses from barium enema examinations.

PURPOSE: To analyse factors behind the variation of patient doses from barium enema (BE) examinations. MATERIAL AND METHODS: The patients' (n=89) organ and effective doses (E) due to BE examinations were computed with the ODS-60 program. An average risk factor for BE examinations was derived using the BEIR V schema. The correlation of E with several independent variables was analysed. RESULTS: Median Es at five hospitals were 4.4, 6.1, 7.1, 13 and 16 mSv. The E of the female patients (median 9.2 mSv) was higher than that of the males (median 5.4 mSv) (p<0.001) due to the higher female doses to the gonads, bladder and uterus, resulting from different body structure. An average fatal risk factor of 0.02%. per one BE examination was derived. Factors controlled by the radiologist (screening time, number of exposures) explained 40% and patient-related factors explained 16% of the total variation of E. The equipment-related factors are included in the residual 44%. CONCLUSION: Due to the large contribution of the radiologists' examination technique in the value of E, an optimal examination technique is essential in reducing doses and the stochastic risk to patients.

Expression of luciferase genes from different origins in Bacillus subtilis.

A group of vectors for luciferase expression in Bacillus subtilis was constructed. So far, only bacterial luciferases have been expressed in Bacillus, but in this study we wanted also to express genes encoding eukaryotic luciferases to perform direct comparisons of the light levels produced by the two different systems in B. subtilis. The vectors constructed can replicate both in Escherichia coli and B. subtilis, and the luciferase expression is strictly regulated due to the dual plasmid system used. Nearly a 100-fold increase in light production compared to previous results was achieved when genes encoding bacterial luciferase were inserted into the constructs and transformed into B. subtilis. An additional tenfold increase in light production was obtained when luciferase genes from the North American firefly (Photinus pyralis) or a click beetle (Pyrophorus plagiophtalamus) were introduced in a similar fashion into B. subtilis. Measurement of the light emission was performed without disruption of bacterial cells in a real-time manner, which is a common feature when working with all of these constructions. Structures of the shuttle vector constructs and results from light emission measurements are presented.

Cluster models in cellular level electron dose calculations.

A program for calculating absorbed dose was developed for radioimmunotherapy (RIT) purposes. It was used to determine the difference in the therapeutic effect of (111)In electrons when using a close-packed cubic geometry and a cell cluster model developed in this project. Our cluster model piles the cells individually. The cells were modelled as spheres of diameters of 12 (tumour) and 30 (healthy) microm. Both models were used to generate clusters with spherical tumours inside healthy tissue. The program uses Monte Carlo-based dose kernels. The radiation spectra were calculated from the Auger and x-ray transition strengths and fluorescence yields of (111)In. The results show the importance of the cluster model in cellular level dose calculations. Near the tumour/healthy tissue interface in particular, the doses differ because of geometrical differences. In the case of a small cluster with tumour and total diameters of 30 and 150 microm, the ratio of the therapeutic effects is 20.

Assessing the effectiveness of warnings and the phenomenological characteristics of false memories.

The phenomenology of false memories was investigated in three experiments in which participants heard two experimenters read lists of items that were related to critical nonpresented items. In Experiments 1, following a recognition memory test, participants rated the phenomenological characteristics of their memories immediately and after a 48-hour delay. False recognition was prevalent and on several dimensions participants rated their true memories as more vivid than their false memories. In Experiments 2 and 3, following the study phase, participants were warned about the phenomenological differences between true and false memories and were instructed to use this information to avoid reporting nonpresented items. This type of warning was ineffective at reducing false recall (Experiment 2) and false recognition (Experiment 3) relative to unwarned participants. Importantly, the inability of explicit warnings to impact illusory recollections demonstrates that the false memories cannot be attributed simply to a criterion shift.

Radiation spectra of 111In, 113mIn and 114mIn.

The radiation spectra of 111In, 113In, and 114mIn are calculated with the Monte Carlo computer program IMRDEC. The relaxation probabilities are taken from the EADL file of the Lawrence Livermore National Laboratory. Because this file does not include data for some N and O transitions, these were additionally determined by applying the Kassis rule. Two schemes are applied to calculate the transition energies: 1) a simple (Z + 1)/Z scheme, and 2) accurate calculation solving the relativistic Dirac equations. It is shown that using the extended set of relaxation probabilities leads to generation of many additional low-energy Auger and CK electrons if the (Z + 1)/Z rule is applied. On the other hand, the emissions of almost all these electrons are rejected if their energies are calculated solving the Dirac equations taking into consideration realistic electron vacancies.