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PubMedDate not supplied

Clinician use of a palmtop drug reference guide.

OBJECTIVE: Problems involving drug knowledge are one of the most common causes of serious medication errors. Although the information that clinicians need is often available somewhere, retrieving it expeditiously has been problematic. At the same time, clinicians are faced with an ever-expanding pharmacology knowledge base. Recently, point-of-care technology has become more widely available and more practical with the advent of handheld, or palmtop, computing. Therefore, the authors evaluated the clinical contribution of a drug database developed for the handheld computer. ePocrates Rx (formerly known as qRx; ePocrates, San Carlos, California) is a comprehensive drug information guide that is downloadable free from the Internet and designed for the Palm OS platform align="right". DESIGN: A seven-day online survey of 3,000 randomly selected ePocrates Rx users was conducted during March 2000. MEASUREMENTS: User technology experience, product evaluation and usage patterns, and the effects of the drug reference database on information-seeking behavior, practice efficiency, decision making, and patient care. RESULTS: The survey response rate was 32 percent (n=946). Physicians reported that ePocrates Rx saves time during information retrieval, is easily incorporated into their usual workflow, and improves drug-related decision making. They also felt that it reduced the rate of preventable adverse drug events. CONCLUSIONS: Self-reported perceptions by responding clinicians endorse improved access to drug information and improved practice efficiency associated with the use of handheld devices. The clinical and practical value of using these devices in clinical settings will clearly grow further as wireless communication becomes more ubiquitous and as more applications become available.

Attitude to Computers↗
PubMed1999

Efficient literature searching in diffuse topics: lessons from a systematic review of research on communicating risk to patients in primary care.

Using the example of communication about risk in a primary care setting, this paper puts forward a method of developing and evaluating a detailed search strategy for locating the literature for a systematic review of a 'diffuse' subject. The aim of this paper is to show how to develop a search strategy that maximizes both recall and precision while keeping search outputs manageable. Six different databases were used, namely Medline, Embase, PsychLIT, CancerLIT, Cinahl and Social Science Citation Index (SSCI). The searches were augmented by hand-searching, contacting authors, citation searching and reference lists from included papers. Other databases were searched but yielded no extra references for this subject matter. Of the 99 papers included, 80 were indexed on Medline. The Medline search strategy identified 54 of them and the remaining 26 were located on other databases. The 19 further unique references were found using the other databases and methods of retrieval. A combination of several databases must be used to maximize recall and to increase the precision of searches on individual databases, thus improving the overall efficiency of the search.

Databases, Bibliographic↗
PubMed2026

Long-read Sequences Mapped to a Complete Reference Genome Uncover Uncaptured Structural Variants across the Beta-globin Cluster in Africans with Sickle Cell Disease.

African genomes are marked by extensive complexity in the number and distribution of variants, yet remain under-represented in genetic databases and the human reference genome. This gap in representation limits the broad application of genomic medicine. Sickle cell disease (SCD) - one of the most common monogenic diseases - has its highest prevalence in Africa, and variation in disease severity has consistently been linked to the beta-globin locus, including levels of fetal hemoglobin (HbF). Modulation of HbF is central to current SCD gene therapies; however, the inherent complexity and variation at the locus in African genomes presents a challenge to translating these advances to Africa. Here, we align long-read single molecule sequences (LRS) targeted to the beta-globin region to the hg38 and T2T-CHM13v2 genome references in 40 individuals with SCD, predominantly recruited from three African countries. We demonstrate that the expanded T2T-CHM13v2 reference sequence at this locus reduces Structural Variant (SV) calls by 70% and uncovers uncaptured single nucleotide variants (SNVs). Across the cluster we report 343 SVs and 196 SNVs that have not been previously reported, including in LRS data from the All of Us project. By including African populations from ethnolinguistic groups that have not been previously surveyed we improve variant resolution and bolster evidence for observed variation. Finally, we identify a common ∼4kb insertion locus overlapping the HBB promoter among individuals with high HbF. These results demonstrate the utility of combining a comprehensive reference genome with LRS in African populations to uncover genomic variation at disease-associated loci.

SNV↗
PubMed2005

Sedation of anxious children undergoing dental treatment.

BACKGROUND: Anxiety about dental treatment maybe a barrier to its uptake in children. Sedation can be used to relieve anxiety and manage behaviour, unfortunately it is difficult to determine from published research which agents, dosages and techniques are effective. OBJECTIVES: To evaluate the relative efficacy of the various conscious sedation techniques and dosages for behaviour management in paediatric dentistry. SEARCH STRATEGY: Computerised: MEDLINE, PubMed, EMBASE, Cochrane Central Register of Controlled Trials, Dissertation Abstracts, SIGLE, the World Wide Web (Google) and the Community of Science Database were searched for relevant trials and references. Searches were carried out for MEDLINE and EMBASE up to June 2003 and for the remaining databases December 2002. Reference lists from relevant articles were scanned and the authors contacted to identify trials and obtain additional information. There were no language restrictions. Trials pre-1966 were not searched. SELECTION CRITERIA: Studies were selected if they met the following criteria: randomised controlled trials of conscious sedation comparing two or more drugs/techniques/placebo undertaken by the dentist or one of the dental team in anxious children up to 16 years of age. DATA COLLECTION AND ANALYSIS: Information regarding methods, participants, interventions and outcome measures and results were independently extracted, in duplicate, by two authors. Specialist advice was asked to categorise interventions. Authors of trials were contacted for details of randomisation and withdrawals and a quality assessment was carried out not using any formal scoring system. The Cochrane Oral Health Group statistical guidelines were followed. MAIN RESULTS: Fifty-three studies were included with 2345 subjects in total. Overall quality of studies was found to be disappointing with poor reporting often the main problem. Data reported could not be easily aggregated into groups to facilitate description of results. Meta-analysis of the available data was also not possible for the same reason. The variety of differing drug regimens compared made it difficult to isolate groups of studies that were sufficiently similar in design to allow sensible comparison. Where groups of studies could be isolated, then the differing outcome measures used made their meta-analysis impossible. AUTHORS' CONCLUSIONS: Authors were not able to reach any definitive conclusion on which was the most effective drug or method of sedation used for anxious children. A list of proposed areas of study was described.

Anti-Anxiety Agents↗
PubMed2006

Guidelines for evaluating chronic cough in pediatrics: ACCP evidence-based clinical practice guidelines.

OBJECTIVES: To review relevant literature and present evidence-based guidelines to assist general and specialist medical practitioners in the evaluation and management of children who present with chronic cough. METHODOLOGY: The Cochrane, MEDLINE, and EMBASE databases, review articles, and reference lists of relevant articles were searched and reviewed by a single author. The date of the last comprehensive search was December 5, 2003, and that of the Cochrane database was November 7, 2004. The authors' own databases and expertise identified additional articles. RESULTS/CONCLUSIONS: Pediatric chronic cough (ie, cough in children aged <15 years) is defined as a daily cough lasting for >4 weeks. This time frame was chosen based on the natural history of URTIs in children and differs from the definition of chronic cough in adults. In this guideline, only chronic cough will be discussed. Chronic cough is subdivided into specific cough (ie, cough associated with other symptoms and signs suggestive of an associated or underlying problem) and nonspecific cough (ie, dry cough in the absence of an identifiable respiratory disease of known etiology). The majority of this section focuses on nonspecific cough, as specific cough encompasses the entire spectrum of pediatric pulmonology. A review of the literature revealed few randomized controlled trials for treatment of nonspecific cough. Management guidelines are summarized in two pathways. Recommendations are derived from a systematic review of the literature and were integrated with expert opinion. They are a general guideline only, do not substitute for sound clinical judgment, and are not intended to be used as a protocol for the management of all children with a coughing illness. Children (aged <15 years) with cough should be managed according to child-specific guidelines, which differ from those for adults as the etiologic factors and treatments for children are sometimes different from those for adults. Cough in children should be treated based on etiology, and there is no evidence for using medications for the symptomatic relief of cough. If medications are used, it is imperative that the children are followed up and therapy with the medications stopped if there is no effect on the cough within an expected time frame. An evaluation of the time to response is important. Irrespective of diagnosis, environmental influences and parental expectations should be discussed and managed accordingly. Cough often impacts the quality of life of both children and parents, and the exploration of parental expectations and fears is often valuable in the management of cough in children.

Chronic Disease↗
PubMed2003

Non-invasive ventilation for cystic fibrosis.

BACKGROUND: The use of non-invasive ventilation (NIV) has been proposed as a means to temporarily reverse or slow the progression of worsening respiratory failure in cystic fibrosis (CF). OBJECTIVES: To compare the effect of NIV versus no NIV in people with CF. SEARCH STRATEGY: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group trials register which comprises references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. The reference lists of each trial were searched for additional publications that may contain other trials. Date of most recent search: January 2002. SELECTION CRITERIA: Relevant randomised controlled trials in which a form of pressure preset or volume preset NIV versus no NIV was used in people with acute or chronic respiratory failure in CF. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trials for inclusion criteria, methodological quality and data extraction. MAIN RESULTS: Six trials were identified and four trials met the inclusion criteria with a total of 55 participants. All of these trials only evaluated single treatment sessions. Two trials (36 participants) evaluated the use of NIV for airway clearance compared with an alternative physiotherapy method. These trials showed that airway clearance may be easier and people with CF may prefer to use NIV for airway clearance. There was no evidence that NIV increases sputum expectoration or improves lung function. Two trials (19 participants) evaluated the use of NIV for overnight ventilatory support. Of the primary outcomes examined in this review, only lung function was evaluated within the two trials. Due to the small numbers of participants and the differing statistical techniques used within the review and the primary trials, there were discrepancies in the results obtained by the RevMan analysis and the original trial analysis. No clear differences were found between NIV compared with either oxygen or room air. REVIEWER'S CONCLUSIONS: Non-invasive ventilation may be a useful adjunct to other airway clearance techniques, particularly in people with CF who have difficulty expectorating sputum. Non-invasive ventilation when used in addition to oxygen may improve gas exchange during sleep to a greater extent than oxygen therapy alone in moderate to severe disease. These benefits of NIV have only been demonstrated in single treatment sessions and its efficacy, safety and acceptability in the longer term are unknown. There is a need for long-term randomised controlled trials to determine the clinical effects of non-invasive ventilation in CF.

Cystic Fibrosis↗
PubMed2003

[Whiplash injury of the neck from concepts to facts].

OBJECTIVES: To focus on a topic of traumatology and rehabilitation becoming recently a much debated public health problem. METHOD: A references search from Medline database with whiplash as keyword was carried out. Were selected articles with abstracts in french or english and focusing on accidentology, biomechanics, demonstrated lesions, epidemiology and treatments. RESULTS: From 1664 references found, 232 were reviewed. The usual mechanism of crash is a rear-end collision inducing in the occupants of the bumped vehicle a sudden lower cervical spine extension with upper flexion followed by a global flexion. In nearly 50% of the cases, the stress occurring in the collision is comparable to that observed in bumper cars. The velocity changes are seldom up to 15 km/h. A headrest at the level of the center of gravity of the head restrict significantly the extension of the neck. Every structure of the cervical spine could be damaged and mainly the facet joints but the lesions were only demonstrated in severes traumatisms. The discrepancies in incidence among the different countries could be related to their medicolegal system. Although subjectives, the early symptoms are rather similar among patients suggesting true anatomical or functional disorders but the chronicity seems to be mainly related to social and psychological factors. The association of: no posterior midline cervical tenderness, no intoxication, normal alertness, no focal neurological deficit and no painful distracting injuries has a good predictive value of the lack of osteo-articular lesion on X-rays. Except the grade IV of the Quebec task Force (0, no symptom; 1, pain and stiffness; 2, neck complaint and physical signs; 3, neck complaint and neurological signs; 4, fracture or dislocation) the use of a collar should be avoided and the cervical spine should be mobilized. CONCLUSION: In most whiplash injuries, the mildness should be early stated, mobilization encouraged, and procedures of compensation shortened.

Accidents, Traffic↗
PubMed2005

The Diatom EST Database.

The Diatom EST database provides integrated access to expressed sequence tag (EST) data from two eukaryotic microalgae of the class Bacillariophyceae, Phaeodactylum tricornutum and Thalassiosira pseudonana. The database currently contains sequences of close to 30,000 ESTs organized into PtDB, the P.tricornutum EST database, and TpDB, the T.pseudonana EST database. The EST sequences were clustered and assembled into a non-redundant set for each organism, and these non-redundant sequences were then subjected to automated annotation using similarity searches against protein and domain databases. EST sequences, clusters of contiguous sequences, their annotation and analysis with reference to the publicly available databases, and a codon usage table derived from a subset of sequences from PtDB and TpDB can all be accessed in the Diatom EST Database. The underlying RDBMS enables queries over the raw and annotated EST data and retrieval of information through a user-friendly web interface, with options to perform keyword and BLAST searches. The EST data can also be retrieved based on Pfam domains, Cluster of Orthologous Groups (COG) and Gene Ontologies (GO) assigned to them by similarity searches. The Database is available at http://avesthagen.sznbowler.com.

DNA, Algal↗
PubMed2025

Characterization of microbial dark matter at scale with MetaSBT and taxonomy-aware Sequence Bloom Trees.

Metagenomics has become a powerful tool for studying microbial communities, allowing researchers to investigate microbial diversity within complex environmental samples. Recent advances in sequencing technology have enabled the recovery of near-complete microbial genomes directly from metagenomic samples, also known as metagenome-assembled genomes (MAGs). However, accurately characterizing these genomes remains a significant challenge due to the presence of sequencing errors, incomplete assembly, and contamination. Here we present MetaSBT, a new tool for organizing, indexing, and characterizing microbial reference genomes and MAGs. It is able to identify clusters of genomes at all seven taxonomic levels, from the kingdom all the way down to the species level, using the Sequence Bloom Tree (SBT) data structure that relies on Bloom Filters (BFs) to index massive amounts of genomes based on their k-mers composition. We have built an initial set of databases composed of over 190 thousand viral genomes from NCBI GenBank and public sources grouped into sequence consistent clusters at different taxonomic levels, making it the first software solution for the classification of viruses at different ranks, including still unknown ones. This results in the definition of over 40 thousand species clusters where ~80% do not match with any known viral species in reference databases to date. Furthermore, we show how our databases can be used as a new basis for existing quantitative metagenomic profilers to unlock the detection of unknown microbes and the estimation of their abundance in metagenomic samples. Finally, the framework is released open-source and, along with its public databases, is fully integrated into the Galaxy Platform enabling broad accessibility.

metagenome-assembled genomes↗
PubMed2004

VSD: a database for schizophrenia candidate genes focusing on variations.

Schizophrenia is a common mental disease characterized by delusions, hallucinations, and formal thought disorder. It has been demonstrated with genetic evidence that the disease is a polygenic disorder. Pharmacological, neurochemical, and clinical studies have suggested a number of schizophrenia susceptibility loci. In order to systematically search for genes with small effect in the development of schizophrenia, a database called VSD was established to provide variation data for publicly available candidate genes. Most of the genes encode neurotransmitter receptors, neurotransmitter transporters, and the enzymes involved in their metabolism. Other candidate genes extracted from published literature are also included. The variation information has been collected from publicly available mutation and polymorphism databases such as dbSNP, HGVbase, and OMIM, with single nucleotide polymorphism (SNP) being the most abundant form of collected variations. Reference sequences from NCBI's RefSeq database are used as references when positioning variation at transcript and protein levels. The nonsynonymous SNPs (nsSNPs) that lead to amino acid changes in the functional sites or domains of proteins are distinguished since they are more likely to affect protein function and would be target SNPs for association studies. In addition to variation data, gene descriptions, enzyme information, and other biological information for each gene locus are also included. The latest version of VSD contains 23,648 variations assigned to a total of 186 genes. Five-hundred eighty-eight domains and sites annotated in the SWISS-PROT and InterPro databases are found to contain nsSNPs. VSD may be accessed via the World Wide Web (www.chgb.org.cn/vsd.htm) and will be developed as an up-to-date and comprehensive locus-specific resource for identifying susceptibility genes for schizophrenia.

Databases, Nucleic Acid↗
PubMedDate not supplied

Therapeutic positioning, wheelchair seating, and pulmonary function of children with cerebral palsy: a research synthesis.

This review analyzed research literature concerning pulmonary function and positioning of persons with cerebral palsy (CP) who lack trunk control. The search reviewed literature published from 1966 through March 2003. Twenty-eight references located by electronic database search were analyzed using Moody's Research Analysis Tool. All reflected either a physiologic or therapy-based model involving function in activities of daily living, but no health outcomes. One reference applied a nursing model to care of developmentally disabled persons, including those with CP. Existing research gaps include the need for human subjects, larger sample sizes, measurement of influence of gravity on body position, greater precision in describing independent variables of positioning, and participation by children with disabilities. This paper proposes a conceptual model using Orem's self-care theory upon which to base nursing interventions, including therapeutic positioning of persons with CP who lack trunk control. Future nursing research should explore health outcomes of various properties of wheelchair positioning.

Cerebral Palsy↗
PubMed2000

Integration of macromolecular diffraction data using radial basis function networks.

This paper presents a novel approach for intensity calculation of X-ray diffraction spots based on a two-stage radial basis function (RBF) network. The first stage uses pre-determined reference profiles from a database as basis functions in order to locate the diffraction spots and identify any overlapping regions. The second-stage RBF network employs narrow basis functions capable of local modifications of the reference profiles leading to a more accurate observed diffraction spot approximation and therefore accurate determination of spot positions and integrated intensities.

Journal Article↗
PubMed2005

Alpha-glucosidase inhibitors for type 2 diabetes mellitus.

BACKGROUND: Alpha-glucosidase inhibitors such as acarbose or miglitol, have the potential to improve glycemic control in type 2 diabetes mellitus. The true value of these agents, especially in relation to diabetes related mortality and morbidity, has never been investigated in a systematic literature review and meta-analysis. OBJECTIVES: To assess the effects of alpha-glucosidase inhibitors s in patients with type 2 diabetes mellitus. SEARCH STRATEGY: We searched The Cochrane Library, MEDLINE, EMBASE, Current Contents, LILACS, databases of ongoing trials, reference lists of reviews on the topic of alpha-glucosidase inhibitors and we contacted experts and manufacturers for additional trials. Date of most recent search: December 2003 (Current Contents) and April 2003 (other databases). SELECTION CRITERIA: Randomised controlled trials of at least 12 weeks duration comparing alpha-glucosidase inhibitor monotherapy in patients with type 2 diabetes with any other intervention and that included at least one of the following outcomes: mortality, morbidity, quality of life, glycemic control, lipids, insulin levels, body weight, adverse events. DATA COLLECTION AND ANALYSIS: Two reviewers read all abstracts, assessed quality and extracted data independently. Discrepancies were resolved by consensus or by the judgement of a third reviewer. A statistician checked all extracted data entrance in the database. We attempted to contact all authors for data clarification. MAIN RESULTS: We included 41 trials (8130 participants), 30 investigated acarbose, seven miglitol, one trial voglibose and three trials compared different alpha-glucosidase inhibitors. Study duration was 24 weeks in most cases and only two studies lasted amply longer than one year. We found only few data on mortality, morbidity and quality of life. Acarbose had a clear effect on glycemic control compared to placebo: glycated haemoglobin -0.8% (95% confidence interval -0.9 to -0.7), fasting blood glucose -1.1 mmol/L (95% confidence interval -1.4 to -0.9), post-load blood glucose -2.3 mmol/L (95% confidence interval -2.7 to -1.9). The effect on glycated haemoglobin by acarbose was not dose-dependent. We found a decreasing effect on post-load insulin and no clinically relevant effects on lipids or body weight. Adverse effects were mostly of gastro-intestinal origin and dose dependent. Compared to sulphonylurea, acarbose decreased fasting and post-load insulin levels by -24.8 pmol/L (95% confidence interval -43.3 to -6.3) and -133.2 pmol/L (95% confidence interval -184.5 to -81.8) respectively and acarbose caused more adverse effects. AUTHORS' CONCLUSIONS: It remains unclear whether alpha-glucosidase inhibitors influence mortality or morbidity in patients with type 2 diabetes. Conversely, they have a significant effect on glycemic control and insulin levels, but no statistically significant effect on lipids and body weight. These effects are less sure when alpha-glucosidase inhibitors are used for a longer duration. Acarbose dosages higher than 50 mg TID offer no additional effect on glycated hemoglobin but more adverse effects instead. Compared to sulphonylurea, alpha-glucosidase inhibitors lower fasting and post-load insulin levels and have an inferior profile regarding glycemic control and adverse effects.

1-Deoxynojirimycin↗
PubMed1992

'References'.

Explore the source record for details and available documents.

Databases, Bibliographic↗
PubMedDate not supplied

The ubiquitin superfamily: members, features, and phylogenies.

The ubiquitin superfamily is a rich repository of small, conserved, functionally unique, and important proteins. Its member proteins fold simply and similarly, with kinetic and thermodynamic ease (Sorenson, J. M.; Head-Gordon, T. Toward minimalist models of larger proteins: A ubiquitin-like protein. Proteins 2002, 46, 368-379). They have been implicated in numerous cancers, neurodegenerations, inflammations, and various disorders affecting signal transduction or protein half-life. These proteins serve the cell generally as portable recognition tags with distinct intracellular roles; indeed, tagging with small protein modifiers has become a new hallmark of post-translational modifications and other signal transduction phenomenon (Finley, D. J. Signal transduction. An alternative to destruction. Nature 2001, 412, 283, 285-286). Because many ubiquitin-like proteins bear similarities in sequence, structure, and function, we gathered protein sequences containing the ubiquitin domain from public databases and created a highly granular and defined protein catabolism database to catalog, summarize, reference, and relate them to their targets and specific ligases (to be described elsewhere). In this paper, we reveal a compilation of proteins possessing the ubiquitin domain. This comprises the first and most important part of our database content. We searched available organismal proteomes for sequence-related members of the ubiquitin superfamily and here present over 200 proteins possessing this domain. These proteins were organized phylogenetically and functionally, thereby defining several new families. To our knowledge, this is the most complete assemblage of ubiquitin domains to date.

Animals↗
PubMed2002

Interventions for treating collagenous colitis.

BACKGROUND: Collagenous colitis is a disorder that is recognized as a cause of chronic diarrhea. Treatment has been based mainly on anecdotal evidence. This review was performed to identify therapies for collagenous colitis that have been proven in randomized trials. OBJECTIVES: To determine effective treatments for patients with clinically active collagenous colitis. SEARCH STRATEGY: Relevant papers published between 1970 and January 2002 were identified via the MEDLINE, PUBMED, and EMBASE databases. Manual searches from the references of identified papers, as well as review papers on collagenous or microscopic colitis were performed to identify additional studies. Abstracts from major gastroenterological meetings were searched to identify research submitted in abstract form only. Finally, the Cochrane Controlled Trials Register and the Cochrane Inflammatory Bowel Disease Group Specialized Trials Register were searched for other studies. SELECTION CRITERIA: Four randomized trials were identified. One trial studied bismuth subsalicylate (published in abstract form only), and 3 trials (2 published in abstract form only) studied budesonide in the therapy of collagenous colitis. DATA COLLECTION AND ANALYSIS: Data were extracted independently by each author onto 2x2 tables (treatment versus placebo and response versus no response). For therapies assessed in one trial only, p-values were derived using the chi-square test. For therapies assessed in more than one trial, summary test statistics were derived using the Peto odds ratio and 95% confidence intervals. Data were combined for analysis only if the outcomes were sufficiently similar in definition. MAIN RESULTS: There were 9 patients with collagenous colitis in the trial studying bismuth subsalicylate (nine 262 mg tablets daily for 8 weeks). Those randomized to active drug were more likely to have clinical (p=0.003) and histological (p=0.003) improvement than those assigned to placebo. A total of 86 patients were enrolled in 3 trials studying budesonide (9 mg daily for 6 to 8 weeks). The pooled odds ratio for clinical response to treatment with budesonide was 16.79 (95% CI 7.28-38.74), with a number needed to treat of 2 patients. There was significant histological improvement with treatment in all 3 trials studying budesonide therapy. REVIEWER'S CONCLUSIONS: Budesonide is effective in the treatment of collagenous colitis. The evidence for bismuth subsalicylate is weaker, but still important. The roles of these and other therapies in inducing or maintaining remission (as opposed to clinical or histological improvement) of collagenous colitis are unknown.

Anti-Inflammatory Agents↗
PubMed1994

Dose-response assessment for developmental toxicity. I. Characterization of database and determination of no observed adverse effect levels.

Developmental toxicity risk assessment currently relies on the estimation of reference doses (RfDDTs) or reference concentrations (RfCDTS) based on the use of no observed adverse effect levels (NOAELs) and uncertainty factors. The benchmark dose (BMD) has been proposed as an alternative basis for reference value calculations. A large database of 246 developmental toxicity experiments (Segment II-type studies) representing 1825 data subsets for various endpoints was compiled for use in comparing NOAEL and BMD approaches to developmental toxicity risk assessment. This paper describes the characteristics of the database used and the estimation of NOAELs using several approaches. For each endpoint evaluated, two NOAELs were calculated using the NOSTASOT procedure (Tukey et al., 1985). The first NOAEL calculation, the QNOAEL, was based on a quantal response where a litter was defined as "affected" if one or more fetuses or implants in the litter had the endpoint of interest. The second NOAEL calculation, the CNOAEL, was based on the proportion of fetuses or implants affected within each litter and was treated as a continuous response variable. Fifty-seven percent of the 246 experiments had at least one endpoint that showed a significant trend with dose. A total of 386 data sets were significant with respect to both the quantal and continuous test of trend. An additional 44 data sets were identified with significant trend only by the quantal approach whereas 177 additional data sets were identified with significant trend tests only by the continuous approach. Thus, the continuous approach appeared to be more powerful in detecting dose-related toxicity, but the patterns detected by the two approaches differed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

The frequency of chromosomal abnormalities in patients referred for fragile X analysis.

The present paper summarizes our existing database on chromosomal abnormalities found in patients referred because of a question of the Fragile X Syndrome during the period from January 1, 1990 to June 30, 1995. Cytogenetic results were derived from testing performed at the cytogenetics laboratory at Rhode Island Hospital. All positive fragile X individuals detected among our sample population represent index patients from separate kindreds. Of a total of 327 cases referred for fragile X testing, 10 (3.06 percent) were found to be positive for fragile X by either cytogenetics alone or by both cytogenetics and DNA testing, 12 (3.60 percent) were found to be positive for either a numerical or structural chromosomal abnormality, while 10 (3.06 percent) were found to exhibit a heteromorphism. Positive chromosomal findings included numerical chromosomal abnormalities of the sex chromosomes and autosomes, deletions, and translocations. Heteromorphism mostly involved an increase in the length of heterochromatic regions of certain chromosomes as well as a pericentric inversion of a chromosome 9, usually considered normal variants. It is concluded that chromosomal abnormalities other than fragile X are found with equal and, in some cases, higher frequency than the frequency of fragile X positivity in patients referred for a question of the Fragile X Syndrome. Our figures, consistent with those reported in the literature, underscore the value of routine karyotyping in this population of patients. Except under special circumstances, it is important that GTG-banding analysis be performed so that the entire human genome be examined in addition to scoring for the fragile X mutation on Xq27.3. Especially in view of the recent finding of the relative rarity of this condition, the exclusive use of DNA analysis is not advised.

Chromosome Aberrations↗