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Biomedical subjects

M B Grace

Publications and source records attributed to M B Grace.

10 recordsLinked to original sources
PubMed2003

Radiation biodosimetry: applications for spaceflight.

The multiparametric dosimetry system that we are developing for medical radiological defense applications could be adapted for spaceflight environments. The system complements the internationally accepted personnel dosimeters and cytogenetic analysis of chromosome aberrations, considered the best means of documenting radiation doses for health records. Our system consists of a portable hematology analyzer, molecular biodosimetry using nucleic acid and antigen-based diagnostic equipment, and a dose assessment management software application. A dry-capillary tube reagent-based centrifuge blood cell counter (QBC Autoread Plus, Becton [correction of Beckon] Dickinson Bioscience) measures peripheral blood lymphocytes and monocytes, which could determine radiation dose based on the kinetics of blood cell depletion. Molecular biomarkers for ionizing radiation exposure (gene expression changes, blood proteins) can be measured in real time using such diagnostic detection technologies as miniaturized nucleic acid sequences and antigen-based biosensors, but they require validation of dose-dependent targets and development of optimized protocols and analysis systems. The Biodosimetry Assessment Tool, a software application, calculates radiation dose based on a patient's physical signs and symptoms and blood cell count analysis. It also annotates location of personnel dosimeters, displays a summary of a patient's dosimetric information to healthcare professionals, and archives the data for further use. These radiation assessment diagnostic technologies can have dual-use applications supporting general medical-related care.

Animals↗
PubMed2002

Real-time quantitative RT-PCR assay of GADD45 gene expression changes as a biomarker for radiation biodosimetry.

PURPOSE: To assess the efficacy of fluorescent-based quantitative reverse transcription-polymerase chain reaction (QRT-PCR) technology to measure gene expression changes (GEC) for rapid, point-of-care radiation dose assessment. MATERIALS AND METHODS: A real-time QRT-PCR assay based on 5'-fluorogenic nuclease TaqMan(TM) methodology was developed, which employs both relative and absolute quantification of a candidate mRNA biomarker. Growth arrest and DNA damage gene 45 (GADD45), a cell-cycle regulation and DNA repair gene, served as the paradigm because of the reported linear dose-response relationship for mRNA induction in the human myeloid tumor cell line (ML-1) over the range of 2-50 cGy. Using an ex vivo whole-blood model, GEC was measured from total blood RNA at 24h and 48 h after (60)Co gamma-ray exposures (0-3 Gy; 0.1 Gy/min). RESULTS: A linear and reproducible up-regulation representing a twofold to fourfold change in GADD45 relative and absolute GEC was confirmed in both intra- and inter-assay analyses. CONCLUSIONS: Primer and probes to detect GADD45 targets using real-time PCR were developed. This is the first report using realtime QRT-PCR to measure radiation-induced GEC dose response. Real-time QRT-PCR using GEC as biomarkers offers rapidity, sensitivity, and reproducibility as a potential efficient biological dosimetry tool applicable in radiation therapy applications and early-response accident biodosimetry.

Biomarkers↗
PubMed2001

Radiation exposure assessment using cytological and molecular biomarkers.

Chromosome aberration analysis is the conventional means of assessing radiation exposure. The Armed Forces Radiobiology Research Institute recently established an alternative method to measure radiation-induced chromosome aberrations in interphase cells. The method uses commercially available chemical agents to induce premature chromosome condensation in resting' G0 human peripheral blood lymphocytes. Then specific whole-chromosome DNA probes are used with fluorescence in situ hybridisation to detect aberrant cells rapidly over a broad dose range. In new research, the real-time fluorogenic 5'-nuclease, or TaqMan, polymerase chain reaction assay is being used to identify radiation-responsive molecular biomarkers, including gene expression targets and DNA mutations. The goal is to establish rapid, precise, high-throughput assay systems that are practical in a variety of radiation exposure scenarios. The new methodologies that have a number of other applications, together with diagnostic software now in development, could improve the United States military's emergency response capability and medical readiness.

5'-Nucleotidase↗
PubMed2001

Biodosimety Assessment Tool: a post-exposure software application for management of radiation accidents.

The Biodosimetry Assessment Tool software application under development will equip health care providers with diagnostic information (clinical signs and symptoms, physical dosimetry, etc.) germane to the management of human radiation casualties. Designed primarily for prompt use after a radiation incident, the user-friendly program facilitates collection, integration, and archiving of data obtained from exposed persons. Data collected in templates are compared with established radiation dose responses obtained from the literature to provide multiparameter dose assessments. The program archives clinical information (e.g., extent of contamination, wounds, infection, etc.) useful for casualty management, displays relevant diagnostic information in a concise format, and can be used to manage both military and civilian radiation accidents. In addition, monitoring of diagnostic information of individuals using this program could potentially minimize the severity of psychological casualties by making a marked impact on the way that both radiation casualties and the worried well view their exposure, dose, and future risk for the development of disease.

Humans↗
PubMed1998

Degradable dUMP outer primers in merged tandem (M/T)-nested PCR: low- and single-copy DNA target amplification.

PCR amplification of DNA from a single initiating genomic molecule or low-copy template often requires two sequential amplification reactions with nested primer pairs to achieve the necessary specificity and sensitivity. Residual outer primers can result in undesired primer activity during the inner nested cycles. To circumvent this problem, we have used dU-containing primers for first round amplification and then uracil N-glycosylase (UNG) to degrade them and the ends of their dU-primer-containing amplified DNA products. We have applied this method to the detection of an exon 11 mutation in the HEXA gene. We have merged the step of a single-tube PCR amplification with outer dU primers with a tandem amplification using non-dU-nested primers (hence, the term merged tandem-nested or M/T-nested PCR). Serial dilutions of genomic DNA showed that this method could amplify a specific target from as few as three haploid genome equivalents of template DNA. Specific products were obtained from the DNA of single cells in 19 of 20 replicates, using 12 outer and 28 inner nested PCR cycles, with an intervening UNG digestion step. When coupled with heteroduplex mutational analysis, this method reliably distinguished mutant versus wild-type HEXA gene fragments amplified from single cells without primer artifact.

Artifacts↗
PubMed1998

Preparation of PCR products for DNA sequencing.

We demonstrate that routine PCR product analytical agarose gels can also serve as preparative gels for quick DNA template purification before sequencing. The band of interest is excised, placed into a Gel Nebulizer inside a Micropure separator and rapidly purified in a single centrifugation step. Gel-purified PCR product, suitable for manual and automated sequencing, is delivered within 10 min.

Centrifugation↗
PubMed1995

Thrombin receptor polymorphism in Chinese hamster.

We report the existence of a new Chinese hamster thrombin receptor allele, characterized by an in-frame insertion of three nucleotides at position 250 of the published sequence. As a consequence, an additional proline is inserted into a proline-rich region of the extracellular amino-terminal domain of the receptor. A corresponding proline at this position is also found in the rat thrombin receptor. A silent base-pair change is found in the cytoplasmic tail of the receptor gene. Single-strand conformation polymorphism and sequence analysis indicate this new receptor allele is present in several cell lines derived from different individual Chinese hamsters. Embryonic CHEF IIC9 cells and primary culture cells are homozygous for this new allele. In contrast, the CCL39 lung fibroblast cell line is heterozygous for both the new and old alleles. Both alleles are transcribed into mRNA and code for functional receptors. Given the allelic distribution and sequence alignment with thrombin receptors from other species, we propose that the new sequence represents the actual predominant allele in Chinese hamster.

Alleles↗
PubMed1995

Genetic and clinical features of 42 kindreds with resistance to thyroid hormone. The National Institutes of Health Prospective Study.

OBJECTIVE: To determine the genetic and clinical features of resistance to thyroid hormone in a study from a single institution. DESIGN: Prospective, controlled study. SETTING: National Institutes of Health. PATIENTS: 104 patients with resistance to thyroid hormone from 42 kindreds and 114 unaffected relatives sharing the patients' environmental and genetic backgrounds. MEASUREMENTS: Thyroid, cardiovascular, psychometric, hearing, speech, and growth testing; thyroid tests done at baseline and after TSH-releasing hormone stimulation; and DNA analysis for detection of mutations in the thyroid hormone receptor beta (TR beta) gene (exons 9 and 10). Assessment of tissue-specific compensation for resistance. RESULTS: Inheritance was autosomal dominant in 22 families, sporadic in 14 families, and unknown in 6 families. We found mutations in 25 kindreds (64 patients); 16 mutations were in exon 9 and 9 were in exon 10 of the TR beta gene. In persons with resistance to thyroid hormone, we measured the increased incidence of goiter (65%), attention-deficit hyperactivity disorder (60%), IQ less than 85 (38%), speech impediment (35%), and short stature (18%). We also described new clinical features, such as frequent ear, nose, and throat infections (56%); low weight-for-height in children (32%); hearing loss (21%); and cardiac abnormalities (18%). Genotype, age, whether the mother had resistance to thyroid hormone, and sex influenced the phenotype. Tissue resistance varied from kindred to kindred and involved, in decreasing order, the pituitary gland, the brain, the bone, the liver, and the heart. CONCLUSIONS: This study underscores the incidence of classic features of resistance to thyroid hormone, describes new clinical characteristics of this condition for the first time, and stresses the heterogeneity of the phenotype.

Adolescent↗
PubMed1995

Allele-specific associated polymorphism analysis: novel modification of SSCP for mutation detection in heterozygous alleles using the paradigm of resistance to thyroid hormone.

Allele-specific polymorphism (ASAP) analysis is a modification of single-strand conformation polymorphism (SSCP) mutation screening under optimized temperature conditions in a minigel format with ethidium bromide detection. ASAP analysis was used to screen for and identify mutations within the human thyroid hormone receptor-beta (hTR-beta) gene. These mutations are the underlying cause of resistance to thyroid hormone (RTH). Eleven dissimilar known hTR-beta mutations and six previously uncharacterized mutations were accurately identified. ASAP screening extends to unique ASAP-DNA fingerprinting as an identifying signature for each novel hTR-beta mutation detected thus far. Gel-plugs from the SSCP gels containing polymorphic single-stranded DNA alleles were used without elution to prepare solid-phase sequencing templates for mutant allele PCR and sequencing (MAPS). The coupling of ASAP analysis with MAPS has eliminated many of the interpretative and technical problems associated with the sequencing of heterozygous alleles. Together, this convenient screening and sequencing methodology offers accuracy, reproducibility, speed, and the potential elimination of all radioactivity, providing a general strategy for future automated detection and characterization of genetic mutations.

Adolescent↗