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The optomotor response: a robust first-line visual screening method for mice.

In both scotopic and photopic conditions, the rotation of a grating was found to elicit head movements in mice. The highest spatial frequency eliciting this optomotor response provided an estimate of visual acuity. In male C57BL/6J mice, visual acuity increased from 0.26cpd in scotopic conditions to 0.52cpd in photopic conditions whereas it was 0.52 cpd in both sets of conditions in 129/SvPas mice. No optomotor response was detected in albino CD1 mice and rd1 retinal degeneration mice although light sensitivity in CD1 mice was attested by photophobia and normal electroretinograms. This rapid and cheap method could provide a powerful test of visual performance in genetically modified and pharmacologically treated mice.

Animals↗

Liver transplantation for acute Budd-Chiari syndrome in identical twin sisters with Factor V leiden mutation.

BACKGROUND: Budd-Chiari syndrome (BCS) is uncommon in the children. The cause of BCS comprises several diseases leading to thrombophilia. Activated protein C resistance as a result of a single gene mutation in factor V, the so called factor V Leiden (FVL), is the most common cause of thrombophilia. METHODS: We report a simultaneous occurrence of BCS in identical twin sisters of 13 years of age with heterozygous FVL mutation. RESULTS: One sister presented with acute BCS leading to fulminant hepatic failure. She underwent liver transplantation with subsequent normalization of activated protein C resistance. The other twin sister, who was diagnosed with extensive thromboses of the inferior vena cava, portal vein, and hepatic veins, was successfully managed by aggressive chemical and mechanical thrombolysis followed by therapeutic anticoagulation. Genomic DNA studies confirmed heterozygosity of FVL mutation in the sisters' father and older brother. CONCLUSIONS: The exact cause of the BCS in children should be thoroughly and rapidly investigated, and, if necessary, immediate family members should also be tested for genetic defects in factor V or concomitant thrombophilia.

Adolescent↗

Evaluation of the Emu-pim-1 transgenic mouse model for short-term carcinogenicity testing.

The value of the chronic rodent carcinogenicity assay in adequately predicting cancer risk in humans has become a matter of debate over the past few years. Therefore, more rapid and accurate alternative tests are urgently needed. Transgenic mouse models, those harboring genetic changes that are relevant to the multistage cancer process, may provide such alternative tests. Transgenic Emu-pim-1 mice, developed by Berns and coworkers in 1989, contain the pimn-1 oncogene, which is expressed at elevated levels in their lymphoid compartments. As a result, these mice are predisposed to the development of T-cell lymphomas. Because of the low incidence of spontaneous tumors and the increased sensitivity to N-ethyl-N-nitrosourea-induced carcinogenesis, Emu-pim-1 mice were suggested to be one of the first potential and attractive candidates to be used in short-term carcinogenicity testing. In the present article, the results from 2 recent short-term assays (with mitomycin C and x-rays) are briefly presented, together with a review of all 11 performed bioassays and their corresponding histopathologic and molecular data. The overall results allow the first evaluation of the Emu-pim-1 mouse model with regard to its usefulness in short-term carcinogenicity testing. It has been shown that the model is primarily suitable as a sensitive short-term assay for genotoxic carcinogens that not only induce (at least) gene mutations and/or large deletions and rearrangements but that also sufficiently target the lymphoid system. However, the Emu-pim-1 mice lack sufficient sensitivity to justify their routine use in short-term carcinogenicity testing in general.

Animals↗

Recovery and use of Plasmodium DNA from malaria rapid diagnostic tests.

The purpose of this study was to show that individual malaria rapid diagnosis tests (MRDTs) could also be used to isolate Plasmodium DNA for genetic studies. We extracted and amplified Plasmodium DNA using two commercial MRDT kits. Phenol/chloroform extraction followed by a nested polymerse chain reaction (PCR) can be used to identify Plasmodium falciparum and Plasmodium vivax from MRDTs. The PCR on MRDT-isolated DNA was more sensitive than antigen capture by MRDT. Satisfactory results were also obtained if older MRDT tests were used, even after long periods of storage at ambient temperature, with no special preservation.

Animals↗

Fundamentals of quality assessment of molecular amplification methods in clinical diagnostics. International Federation of Clinical Chemistry Scientific Division Committee on Molecular Biology Techniques.

The increasing interest in molecular biology diagnostics is a result of the tremendous gain of scientific knowledge in genetics, made possible especially since the introduction of amplification techniques. High expectations have been placed on genetic testing, and the number of laboratories now using the relevant technology is rapidly increasing--resulting in an obvious need for standardization and definition of laboratory organization. This communication is an effort towards that end. We address aspects that should be considered when structuring a new molecular diagnostic laboratory, and we discuss individual preanalytical and analytical procedures, from sampling to evaluation of assay results. In addition, different means of controlling contamination are discussed. Because the methodology is in constant change, no general standards can be defined. Accordingly, this publication is intended to serve as a recommendation for good laboratory practice and internal quality control and as a guide to troubleshooting, primarily in amplification techniques.

Chemistry, Clinical↗

Evolution of late-life mortality in Drosophila melanogaster.

Aging appears to cease at late ages, when mortality rates roughly plateau in large-scale demographic studies. This anomalous plateau in late-life mortality has been explained theoretically in two ways: (1) as a strictly demographic result of heterogeneity in life-long robustness between individuals within cohorts, and (2) as an evolutionary result of the plateau in the force of natural selection after the end of reproduction. Here we test the latter theory using cohorts of Drosophila melanogaster cultured with different ages of reproduction for many generations. We show in two independent comparisons that populations that evolve with early truncation of reproduction exhibit earlier onset of mortality-rate plateaus, in conformity with evolutionary theory. In addition, we test two population genetic mechanisms that may be involved in the evolution of late-life mortality: mutation accumulation and antagonistic pleiotropy. We test mutation accumulation by crossing genetically divergent, yet demographically identical, populations, testing for hybrid vigor between the hybrid and nonhybrid parental populations. We found no difference between the hybrid and nonhybrid populations in late-life mortality rates, a result that does not support mutation accumulation as a genetic mechanism for late-life mortality, assuming mutations act recessively. Finally, we test antagonistic pleiotropy by returning replicate populations to a much earlier age of last reproduction for a short evolutionary time, testing for a rapid indirect response of late-life mortality rates. The positive results from this test support antagonistic pleiotropy as a genetic mechanism for the evolution of late-life mortality. Together these experiments comprise the first corroborations of the evolutionary theory of late-life mortality.

Aging↗

Rapid blood clearance of immunoglobulin G2a and immunoglobulin G2b in nude mice.

An extremely rapid blood clearance rate of murine IgG2a antibodies was found in all strains tested of outbred Swiss nu/nu mice, including mice from the major commercial suppliers. The clearance half-life was less than 5 h, in comparison to a 4-5-day half-life in BALB/c mice. Therefore, most of the IgG2a antibody injected i.v. in such mice is cleared before it can reach interstitial fluid, which interferes with immunotherapy and immunodetection experiments. Individual nude mice varied greatly in their IgG2a clearance rates, which hampered investigation of the phenomena. In our experience, approximately three-fourths of nude mice had a rapid or intermediate clearance rate, whereas the remainder had an approximately normal clearance rate. The clearance rate in nude mice was age-dependent, at least in some instances, in that a rapid clearance rate was observed at 2 months of age, whereas the same mice retested at 4 months of age had a normal clearance rate. Rapid clearance could be inhibited by increasing the dose injected: 100 micrograms/mouse resulted in a normal clearance rate, whereas 30 micrograms/mouse was insufficient to inhibit rapid clearance. The clearance rate of IgG2b antibodies was affected similarly to that of IgG2a, whereas the clearance rate of IgG1 and IgG3 was not affected. The Fc region of IgG2a was required in order for rapid clearance to occur. Biodistribution experiments demonstrated that rapid blood clearance was due, at least partially, to binding to the liver and spleen. To determine the genetic basis for rapid IgG2a clearance, approximately 20 inbred and outbred mouse strains were tested. Unexpectedly, nu/+ as well as nu/nu outbred Swiss mice displayed rapid clearance, whereas control +/+ mice did not, so this phenotype appears to be a dominant effect of the nu mutation. BALB/c nu/nu and nu/+ mice did not display rapid clearance, which may be due to expression of the Igh-1a gene, which codes for the IgG2a present in BALB/c mice and in the monoclonal antibodies used in these studies. In conclusion, this clearance effect must be considered in experiments involving murine IgG2a or IgG2b antibodies in outbred Swiss nude mice, except those in which high antibody doses of greater than 0.1 mg/mouse are used. One method of circumventing this problem is to increase the antibody dose injected; a better but more long-range method is to develop strains of outbred nude mice that do have this characteristic.

Animals↗

Genome screens using linkage disequilibrium tests: optimal marker characteristics and feasibility.

Linkage disequilibrium (LD) testing has become a popular and effective method of fine-scale disease-gene localization. It has been proposed that LD testing could also be used for genome screening, particularly as dense maps of diallelic markers become available and automation allows inexpensive genotyping of diallelic markers. We compare diallelic markers and multiallelic markers in terms of sample sizes required for detection of LD, by use of a single marker locus in a case-control study, for rare monophyletic diseases with Mendelian inheritance. We extrapolate from our results to discuss the feasibility of single-marker LD screening in more-complex situations. We have used a deterministic population genetic model to calculate the expected power to detect LD as a function of marker density, age of mutation, number of marker alleles, mode of inheritance of a rare disease, and sample size. Our calculations show that multiallelic markers always have more power to detect LD than do diallelic markers (under otherwise equivalent conditions) and that the ratio of the number of diallelic to the number of multiallelic markers needed for equivalent power increases with mutation age and complexity of mode of inheritance. Power equivalent to that achieved by a multiallelic screen can theoretically be achieved by use of a more dense diallelic screen, but mapping panels of the necessary resolution are not currently available and may be difficult to achieve. Genome screening that uses single-marker LD testing may therefore be feasible only for young (<20 generations), rare, monophyletic Mendelian diseases, such as may be found in rapidly growing genetic isolates.

Alleles↗

The genetics of ovarian cancer: concepts in testing and counseling.

The discovery and sequencing of the BRCA1 gene is an exciting breakthrough for women and health care providers. BRCA1 is associated with inherited breast and ovarian cancer and the body of scientific information regarding its role in ovarian cancer is growing rapidly. The impact of this knowledge on counseling women with a family history of breast or ovarian cancer is profound. This review provides information about familial ovarian cancer syndromes and the emerging role of genetic testing in women with an inherited susceptibility for cancer.

DNA, Neoplasm↗

Mapping critical residues in eukaryotic DNA-binding proteins: a plasmid-based genetic selection strategy with application to the Oct-2 POU motif.

Discrimination between allowed and disallowed amino acid substitutions provides a powerful method for analysis of protein structure and function. Site-directed mutagenesis allows specific hypotheses to be tested, but its systematic application to entire structural motifs is inefficient. This limitation may be overcome by genetic selection, which allows rapid scoring of thousands of randomly (or pseudorandomly) generated mutants. To facilitate structural dissection of DNA-binding proteins, we have designed two generally applicable bacterial selection systems: pPLUS selects for the ability of a protein to bind to a user-defined DNA sequence, whereas pMINUS selects against such binding. Complementary positive and negative selections allow rapid mapping of critical residues. To test and calibrate the systems, we have investigated the bipartite POU domain of the human B-cell-specific transcription factor Oct-2. (i) An invariant residue (Asn347) in the DNA-recognition helix of the POU-specific homeodomain (POUHD) was substituted by each of the 19 other possible amino acids. The mutant proteins each exhibited decreased specific DNA binding as defined in vivo by genetic selection and in vitro by gel retardation; relative affinities correlate with phenotypes in the positive and negative selection systems. An essential role for Asn347 in wild-type POUHD-DNA recognition is consistent with homologous Asn-adenine interactions in cocrystal structures of canonical homeodomains. (ii) Extension of pPLUS/pMINUS selection to the POU-specific subdomain (POUs) is demonstrated by analysis of mutations in its putative helix-turn-helix (HTH) element.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗

Carcinogenicity and mutagenicity testing, then and now.

Cancer is a dread disease worldwide. Mortality of individuals suffering from cancer is high, despite the current improved methods of precocious detection, surgery and therapy. Prevention of cancer is the recognized goal of many activities in cancer research. This aim was recognized early to involve the bioassay of environmental chemicals or mixtures. The first such study involved application of coal tar to the ear of rabbits, and later on to the skin of mice. Subsequently, laboratory rats were introduced, and hamsters were utilized as a substitute for the unwieldy tests in rabbits. Investigators also became concerned with the mechanisms of carcinogenesis, and more definitive approaches to carcinogen bioassay in laboratory animals, as possible indicators of cancer risk in humans. These tests were expensive and lengthy, and did not serve the important purpose of accurately measuring risk of cancer to humans. Once it was realized that DNA and the genetic apparatus might be a key target, rapid bioassays in bacterial and mammalian cell systems were introduced successfully. Thus, batteries of tests are now available to detect effectively human cancer risks, and provide novel approaches to determine the underlying mechanisms, as a sound basis for cancer prevention.

Animals↗

Periodontal risk assessment, diagnosis and treatment planning.

The prevention and treatment of the periodontal diseases is based on accurate diagnosis, reduction or elimination of causative agents, risk management and correction of the harmful effects of disease. Prominent and confirmed risk factors or risk predictors for periodontitis in adults include smoking, diabetes, race, P. gingivalis, P. intermedia, low education, infrequent dental attendance and genetic influences. Several other specific periodontal bacteria, herpesviruses, increased age, male, sex, depression, race, traumatic occlusion and female osteoporosis in the presence of heavy dental calculus have been shown to be associated with loss of periodontal support and can be considered to be risk indicators of periodontitis. The presence of furcation involvement, tooth mobility, and a parafunctional habit without the use of a biteguard are associated with a poorer periodontal prognosis following periodontal therapy. An accurate diagnosis can only be made by a thorough evaluation of data that have been systematically collected by: 1) patient interview, 2) medical consultation as indicated, 3) clinical periodontal examination, 4) radiographic examination, and 5) laboratory tests as needed. Clinical signs of periodontal disease such as pocket depth, loss of clinical attachment and bone loss are cumulative measures of past disease. They do not provide the dentist with a current assessment of disease activity. In an attempt to improve the ability to predict future disease progression, several types of diagnostic tests have been studied, including host inflammatory products and mediators, enzymes, tissue breakdown products and subgingival temperature. In general, the usefulness of these tests for predicting future disease activity remains to be established in terms of sensitivity, specificity and predictive value. Although microbiological analysis of subgingival plaque is not necessary to diagnose and treat most patients with periodontitis, it is helpful when treating patients with unusual forms of periodontal disease such as early-onset, refractory and rapidly progressive disease. There appears to be a strong genetic component in some types of periodontal disease and genetic testing for disease susceptibility has potential for future use, but more research is needed to determine its utility for use in clinical practice. Treatment of the periodontal diseases may be divided into four phases: systemic, hygienic, corrective and maintenance or supportive periodontal therapy. Regardless of the type of treatment provided, periodontal therapy will fail or will be less effective in the absence of adequate supportive periodontal therapy.

Bacteriological Techniques↗

[Molecular genetic testing in amniotic fluid].

The recent progress in cloning and sequencing the genes responsible for genetic diseases and the use of Polymerase Chain Reaction (PCR) allow to test genetic diseases with a few quantity of DNA. Amniotic cells are easily sampled by using amniocentesis. When abnormal ultrasound allows to suspect a genetic disease, PCR on DNA from amniotic cells is a very efficient test to confirm or exclude the presence of the disease. Microsatellites sequences can be used on amniotic cells as a rapid test for chromosomal aneuploidies.

Amniocentesis↗

[Application of VNTR D17S30 locus polymorphism in the paternity test].

A sensitive and rapid PCR-based technique was adopted to genotype the VNTR D17S30 locus. It was confirmed through the genetic analysis of 20 normal families that the inheritance of D17S30 locus coincides with Mendelian law as simple co-dominant. Retrospective analysis of 100 paternity cases demonstrated that D17S30 locus could be used in forensic paternity test in our country. The exclusion probability estimated from allele frequencies of D17S30 locus (74.04%) does not differ significantly from the observed rate of exclusion (80.00%) in these cases. In all excluded paternity cases there are two in which the exclusion evidence is solely provided by the D17S30 locus.

Chromosomes, Human, Pair 17↗

Identification of tumor entities of renal cell carcinoma using interphase fluorescence in situ hybridization.

PURPOSE: We developed a rapid interphase fluorescence in situ hybridization (FISH) test to differentiate renal cell carcinoma (RCC) based on known genetic alterations and verified the suitability of this test for practical use. MATERIALS AND METHODS: We composed 2 FISH test sets using 6 centromere specific and 2 region specific DNA probes of human chromosomes. Test set 1 contained centromeric probes for chromosomes 1, 2, 6 and 9, as labeled by 4 fluorescence dyes. For test set 2 we chose 3p24pter and 3p13p14 regions, and centromeric probes of chromosomes 7 and 17. Interphase nuclei of tumor specimens were prepared from 50 mum frozen tissue sections and fixed on slides. The 2 sets were hybridized simultaneously side by side on the same slide. RESULTS: Seven clear cell carcinomas, 8 papillary carcinomas, 7 chromophobe RCCs and 3 oncocytomas were analyzed by interphase FISH. Results were compared with comparative genomic hybridization findings and pathological reports. Genetic alterations were detected in 22 of 25 analyzed tumors by FISH. FISH findings absolutely correlated with comparative genomic hybridization results. Of the analyzed carcinomas 22 could be identified correctly. In 3 tumors the histological subtypes were revised. CONCLUSIONS: The results of this study demonstrate that the performed test set allows the accurate identification of RCC in 1 hybridization step. Therefore, FISH represents an effective method for the rapid classification of RCC.

Carcinoma, Renal Cell↗

Mutations causing aspartylglucosaminuria (AGU): a lysosomal accumulation disease.

This article provides a review of the mutations reported so far in the lysosomal storage disease aspartylglucosaminuria (AGU). The clinical symptoms, biochemical findings, and diagnostic possibilities of the disease are introduced. The prevalence and biological consequences of the found mutations are then described, as well as the availability of a new rapid DNA test suitable for carrier screening. This test will be especially applicable in the genetically isolated Finnish population, where the carrier frequency of AGU was found to be as high as 1:36. Finally, future prospects dealing with the foreseeable therapeutic interventions of the disease are discussed.

Acetylglucosamine↗

MEMS-based sample preparation for molecular diagnostics.

Completion of the Human Genome Project is driving the rapid development of molecular diagnostics in the laboratory. To accelerate the penetration of genetic tests and other nucleic acid-based tests into clinical markets, simple, compact, automatic sample-preparation systems for molecular diagnostics must be developed. Microelectromechanical systems (MEMS) is a promising approach for the development of automated sample preparation for the clinical laboratory or point-of-care setting. This review discusses MEMS-based components that could be applied to the different stages of the sample-preparation process such as cell separation, nucleic acid purification, and nucleic acid amplification. Examples of functional component integration are given. Issues discussed include partitioning of functions between the instrument and disposable unit, methods of propulsion of fluids and particles, vapor and liquid barriers, and sample size. Although further evaluation and development are needed to provide practical solutions to some of these issues, we conclude that MEMS-based components might contribute to some components in a sample-preparation system consisting of modular instruments and disposable units, but will not provide a generic or a totally integrated solution.

DNA, Bacterial↗