MR-based proton density fat fraction (PDFF) of the vertebral bone marrow differentiates between patients with and without osteoporotic vertebral fractures

The bone marrow proton density fat fraction (PDFF) assessed with MRI enables the differentiation between osteoporotic/osteopenic patients with and without vertebral fractures. Therefore, PDFF may be a potentially useful biomarker for bone fragility assessment.

INTRODUCTION

To evaluate whether magnetic resonance imaging (MRI)-based proton density fat fraction (PDFF) of vertebral bone marrow can differentiate between osteoporotic/osteopenic patients with and without vertebral fractures.

METHODS

Of the 52 study patients, 32 presented with vertebral fractures of the lumbar spine (66.4 ± 14.4 years, 62.5% women; acute low-energy osteoporotic/osteopenic vertebral fractures, N = 25; acute high-energy traumatic vertebral fractures, N = 7). These patients were frequency matched for age and sex to patients without vertebral fractures (N = 20, 69.3 ± 10.1 years, 70.0% women). Trabecular bone mineral density (BMD) values were derived from quantitative computed tomography. Chemical shift encoding-based water-fat MRI of the lumbar spine was performed, and PDFF maps were calculated. Associations between fracture status and PDFF were assessed using multivariable linear regression models.

RESULTS

Over all patients, mean PDFF and trabecular BMD correlated significantly (r =  - 0.51, P < 0.001). In the osteoporotic/osteopenic group, those patients with osteoporotic/osteopenic fractures had a significantly higher PDFF than those without osteoporotic fractures after adjusting for age, sex, weight, height, and trabecular BMD (adjusted mean difference [95% confidence interval], 20.8% [10.4%, 30.7%]; P < 0.001), although trabecular BMD values showed no significant difference between the subgroups (P = 0.63). For the differentiation of patients with and without vertebral fractures in the osteoporotic/osteopenic subgroup using mean PDFF, an area under the receiver operating characteristic (ROC) curve (AUC) of 0.88 (P = 0.006) was assessed. When evaluating all patients with vertebral fractures, those with high-energy traumatic fractures had a significantly lower PDFF than those with low-energy osteoporotic/osteopenic vertebral fractures (P < 0.001).

CONCLUSION

MR-based PDFF enables the differentiation between osteoporotic/osteopenic patients with and without vertebral fractures, suggesting the use of PDFF as a potential biomarker for bone fragility.

Donor-matched comparison of chondrogenic progenitors resident in human infrapatellar fat pad, synovium, and periosteum - implications for cartilage repair

Purpose: There is a clinical need to better characterize tissue sources being used for stem cell therapies. This study focuses on comparison of cells and connective tissue progenitors (CTPs) derived from native human infrapatellar fatpad (IPFP), synovium (SYN), and periosteum (PERI). Materials and Methods: IPFP, SYN, PERI were harvested from twenty-eight patients undergoing arthroplasty. CTPs were quantitatively characterized using automated colony-forming-unit assay to compare total nucleated cell concentration-[Cell], cells/mg; prevalence-(P_CTP), CTPs/million nucleated cells; CTP concentration-[CTP], CTPs/mg; proliferation and differentiation potential; and correlate outcomes with patient's age and gender. Results: [Cell] did not differ between IPFP, SYN, and PERI. P_CTP was influenced by age and gender: patients >60 years, IPFP and SYN had higher P_CTP than PERI (p < 0.001) and females had higher P_CTP in IPFP (p < 0.001) and SYN (p = 0.001) than PERI. [CTP] was influenced by age: patients <50 years, SYN (p = 0.0165) and PERI (p < 0.001) had higher [CTP] than IPFP; patients between 60 and 69 years, SYN (p < 0.001) had higher [CTP] than PERI; patients >70 years, IPFP (p = 0.006) had higher [CTP] than PERI. In patients >60 years, proliferation potential of CTPs differed significantly (SYN>IPFP>PERI); however, differentiation potentials were comparable between all three tissue sources. Conclusion: SYN and IPFP may serve as a preferred tissue source for patients >60 years, and PERI along with SYN and IPFP may serve as a preferred tissue source for patients <60 years for cartilage repair. However, the heterogeneity among the CTPs in any given tissue source suggests performance-based selection might be useful to optimize cell-sourcing strategies to improve efficacy of cellular therapies for cartilage repair.

Insights into genetics, human biology and disease gleaned from family based genomic studies

Identifying genes and variants contributing to rare disease phenotypes and Mendelian conditions informs biology and medicine, yet potential phenotypic consequences for variation of >75% of the ~20,000 annotated genes in the human genome are lacking. Technical advances to assess rare variation genome-wide, particularly exome sequencing (ES), enabled establishment in the United States of the National Institutes of Health (NIH)-supported Centers for Mendelian Genomics (CMGs) and have facilitated collaborative studies resulting in novel "disease gene" discoveries. Pedigree-based genomic studies and rare variant analyses in families with suspected Mendelian conditions have led to the elucidation of hundreds of novel disease genes and highlighted the impact of de novo mutational events, somatic variation underlying nononcologic traits, incompletely penetrant alleles, phenotypes with high locus heterogeneity, and multilocus pathogenic variation. Herein, we highlight CMG collaborative discoveries that have contributed to understanding both rare and common diseases and discuss opportunities for future discovery in single-locus Mendelian disorder genomics. Phenotypic annotation of all human genes; development of bioinformatic tools and analytic methods; exploration of non-Mendelian modes of inheritance including reduced penetrance, multilocus variation, and oligogenic inheritance; construction of allelic series at a locus; enhanced data sharing worldwide; and integration with clinical genomics are explored. Realizing the full contribution of rare disease research to functional annotation of the human genome, and further illuminating human biology and health, will lay the foundation for the Precision Medicine Initiative.

Primary Cells Isolated from Human Knee Cartilage Reveal Decreased Prevalence of Progenitor Cells but Comparable Biological Potential During Osteoarthritic Disease Progression

BACKGROUND

Current decisions on cellular therapies for osteoarthritis are based primarily on clinical experience or on assumptions about preferred cell sourcing. They have not been informed by rigorous standardized measurements of the chondrogenic connective-tissue progenitors (CTP-Cs) or their intrinsic diversity of chondrogenic potential. The goal of this study was to quantitatively define the CTP-Cs resident in cartilage of different grades of osteoarthritis and to compare their concentration, prevalence, and biological potential.

METHODS

Twenty-three patients who had varus malalignment of the knee and were scheduled to undergo elective total knee arthroplasty for idiopathic osteoarthritis and who had grade 1-2 osteoarthritis on the lateral femoral condyle and grade 3-4 osteoarthritis on the medial femoral condyle were recruited for study of the cartilage removed during surgery. CTP-Cs were assayed by a standardized colony-forming-unit assay using automated image-analysis software based on ASTM standard test method F2944-12.

RESULTS

Cell concentration was significantly greater (p < 0.001) in grade 3-4 cartilage than in grade 1-2 cartilage. The prevalence of CTP-Cs varied widely, but it trended lower in grade 3-4 cartilage than in grade 1-2 samples (p = 0.078). The biological performance of CTP-Cs from grade 1-2 and grade 3-4 cartilage was comparable. Increased cell concentration was a significant predictor of decreased CTP-C prevalence (p = 0.002).

CONCLUSIONS

Although grade 3-4 cartilage showed fewer CTP-Cs than grade 1-2 cartilage, the range of biological performance was comparable, which suggests that either may be used as a source for potent CTP-Cs. However, the biological reason for the heterogeneity of CTP-Cs in cartilage and the biological implications of that heterogeneity are not well understood and require further study.

CLINICAL RELEVANCE

In order to improve the efficacy of cartilage cell therapy procedures, it is key to characterize the quality and quantity of the cells and progenitors being administered. Additionally, understanding the heterogeneity in order to select appropriate subsets of populations will improve the rigor of decisions concerning cell sourcing and targeting for pharmacological and cellular therapies.

New tools for Mendelian disease gene identification: PhenoDB variant analysis module; and GeneMatcher, a web-based tool for linking investigators with an interest in the same gene

Identifying the causative variant from among the thousands identified by whole-exome sequencing or whole-genome sequencing is a formidable challenge. To make this process as efficient and flexible as possible, we have developed a Variant Analysis Module coupled to our previously described Web-based phenotype intake tool, PhenoDB (http://researchphenodb.net and http://phenodb.org). When a small number of candidate-causative variants have been identified in a study of a particular patient or family, a second, more difficult challenge becomes proof of causality for any given variant. One approach to this problem is to find other cases with a similar phenotype and mutations in the same candidate gene. Alternatively, it may be possible to develop biological evidence for causality, an approach that is assisted by making connections to basic scientists studying the gene of interest, often in the setting of a model organism. Both of these strategies benefit from an open access, online site where individual clinicians and investigators could post genes of interest. To this end, we developed GeneMatcher (http://genematcher.org), a freely accessible Website that enables connections between clinicians and researchers across the world who share an interest in the same gene(s).

The Genetic Basis of Mendelian Phenotypes: Discoveries, Challenges, and Opportunities

Discovering the genetic basis of a Mendelian phenotype establishes a causal link between genotype and phenotype, making possible carrier and population screening and direct diagnosis. Such discoveries also contribute to our knowledge of gene function, gene regulation, development, and biological mechanisms that can be used for developing new therapeutics. As of February 2015, 2,937 genes underlying 4,163 Mendelian phenotypes have been discovered, but the genes underlying ∼50% (i.e., 3,152) of all known Mendelian phenotypes are still unknown, and many more Mendelian conditions have yet to be recognized. This is a formidable gap in biomedical knowledge. Accordingly, in December 2011, the NIH established the Centers for Mendelian Genomics (CMGs) to provide the collaborative framework and infrastructure necessary for undertaking large-scale whole-exome sequencing and discovery of the genetic variants responsible for Mendelian phenotypes. In partnership with 529 investigators from 261 institutions in 36 countries, the CMGs assessed 18,863 samples from 8,838 families representing 579 known and 470 novel Mendelian phenotypes as of January 2015. This collaborative effort has identified 956 genes, including 375 not previously associated with human health, that underlie a Mendelian phenotype. These results provide insight into study design and analytical strategies, identify novel mechanisms of disease, and reveal the extensive clinical variability of Mendelian phenotypes. Discovering the gene underlying every Mendelian phenotype will require tackling challenges such as worldwide ascertainment and phenotypic characterization of families affected by Mendelian conditions, improvement in sequencing and analytical techniques, and pervasive sharing of phenotypic and genomic data among researchers, clinicians, and families.

Evaluation of rhBMP-2/collagen/TCP-HA bone graft with and without bone marrow cells in the canine femoral multi defect model

Recombinant human bone morphogenetic protein-2, when applied to an absorbable type 1 bovine collagen sponge (rhBMP-2/ACS) is an effective therapy in many bone grafting settings. Bone marrow aspirate (BMA) has also been used as a source of transplantable osteogenic connective tissue progenitors. This study was designed to characterize the performance of a scaffold comprising rhBMP-2/ACS in which the sponge wraps around tri-calcium phosphate hydroxyapatite granules (rhBMP-2/ACS/TCP-HA) and to test the hypothesis that addition of BMA will improve the performance of this construct in the Canine Femoral Multi Defect Model. In each subject, two sites were grafted with rhBMP-2/ACS/TCP-HA scaffold loaded with BMA clot and two other sites with rhBMP-2/ACS/TCP-HA scaffold loaded with wound blood (WB). After correction for unresorbed TCP-HA granules, sites grafted with rhBMP-2/ACS/TCP-HA+BMA and rhBMP-2/ACS/TCP-HA+WB were similar, with mean percent bone volumes of 10.9 %±1.2 and 11.2 %±1.2, respectively. No differences were seen in quantitative histomorphometry. While bone formation using both constructs was robust, this study did not support the hypothesis that the addition of unprocessed bone marrow aspirate clot improved bone regeneration in a site engrafted with rhBMP-2/ACS/TCP-HA+BMA. In contrast to prior studies using this model, new bone formation was greater at the center of the defect where TCP-HA was distributed. This finding suggests a potential synergy between rhBMP-2 and the centrally placed ceramic and cellular components of the graft construct. Further optimization may also require more uniform distribution of TCP-HA, alternative cell delivery strategies, and a more rigorous large animal segmental defect model.

PhenoDB: a new web-based tool for the collection, storage, and analysis of phenotypic features

To interpret whole exome/genome sequence data for clinical and research purposes, comprehensive phenotypic information, knowledge of pedigree structure, and results of previous clinical testing are essential. With these requirements in mind and to meet the needs of the Centers for Mendelian Genomics project, we have developed PhenoDB (http://phenodb.net), a secure, Web-based portal for entry, storage, and analysis of phenotypic and other clinical information. The phenotypic features are organized hierarchically according to the major headings and subheadings of the Online Mendelian Inheritance in Man (OMIM®) clinical synopses, with further subdivisions according to structure and function. Every string allows for a free-text entry. All of the approximately 2,900 features use the preferred term from Elements of Morphology and are fully searchable and mapped to the Human Phenotype Ontology and Elements of Morphology. The PhenoDB allows for ascertainment of relevant information from a case in a family or cohort, which is then searchable by family, OMIM number, phenotypic feature, mode of inheritance, genes screened, and so on. The database can also be used to format phenotypic data for submission to dbGaP for appropriately consented individuals. PhenoDB was built using Django, an open source Web development tool, and is freely available through the Johns Hopkins McKusick-Nathans Institute of Genetic Medicine (http://phenodb.net).

Genome-wide allelotypes of familial pancreatic adenocarcinomas and familial and sporadic intraductal papillary mucinous neoplasms

PURPOSE

Most familial cancer susceptibility genes are tumor suppressor genes that are biallelically inactivated in familial neoplasms through somatic deletion of the wild-type allele. Identifying the genomic losses that occur in pancreatic neoplasms, particularly those that occur in familial and precursor neoplasms, may help localize the genes responsible for pancreatic cancer susceptibility.

EXPERIMENTAL DESIGN

Normal and neoplastic tissue DNA was isolated from fresh-frozen surgically resected tissues from 20 patients with primary familial pancreatic adenocarcinoma (defined as having at least one first-degree relative with pancreatic cancer), 31 with sporadic intraductal papillary mucinous neoplasms (IPMN), and 7 with familial IPMNs using laser capture microdissection. Microdissected DNA was whole genome amplified using multiple strand displacement. Genome-wide allelotypes were determined using 391 microsatellite markers. The accuracy of microdissection and fidelity of the whole genome amplification were determined by comparing the genotypes of microdissected primary pancreatic cancers to the genotypes of xenografts derived from these cancers and by comparing the results of amplified to nonamplified specimens.

RESULTS

The concordance of genotypes between LCM whole genome amplified primary pancreatic cancers and their corresponding pancreatic cancer xenograft DNAs was 98%. Among the 20 primary familial pancreatic adenocarcinomas, we found a high prevalence of loss of heterozygosity (LOH) with an average fractional allelic loss (FAL) of 49.9% of an aggregate of 2,378 informative markers. The level of FAL in the IPMNs (10%) was significantly lower than in the pancreatic adenocarcinomas. The most common locus of LOH in the IPMNs was at 19p (LOH at 24% of markers). The regions of frequent allelic loss observed in the familial pancreatic cancers were similar to those found in sporadic pancreatic cancers.

CONCLUSIONS

The allelic loss patterns of familial and sporadic pancreatic cancers and IPMNs provide clues as to the genomic locations of tumor suppressor genes inactivated in these neoplasms.

Genome-wide allelotypes of familial pancreatic adenocarcinomas and familial and sporadic intraductal papillary mucinous neoplasms

PURPOSE

Most familial cancer susceptibility genes are tumor suppressor genes that are biallelically inactivated in familial neoplasms through somatic deletion of the wild-type allele. Identifying the genomic losses that occur in pancreatic neoplasms, particularly those that occur in familial and precursor neoplasms, may help localize the genes responsible for pancreatic cancer susceptibility.

EXPERIMENTAL DESIGN

Normal and neoplastic tissue DNA was isolated from fresh-frozen surgically resected tissues from 20 patients with primary familial pancreatic adenocarcinoma (defined as having at least one first-degree relative with pancreatic cancer), 31 with sporadic intraductal papillary mucinous neoplasms (IPMN), and 7 with familial IPMNs using laser capture microdissection. Microdissected DNA was whole genome amplified using multiple strand displacement. Genome-wide allelotypes were determined using 391 microsatellite markers. The accuracy of microdissection and fidelity of the whole genome amplification were determined by comparing the genotypes of microdissected primary pancreatic cancers to the genotypes of xenografts derived from these cancers and by comparing the results of amplified to nonamplified specimens.

RESULTS

The concordance of genotypes between LCM whole genome amplified primary pancreatic cancers and their corresponding pancreatic cancer xenograft DNAs was 98%. Among the 20 primary familial pancreatic adenocarcinomas, we found a high prevalence of loss of heterozygosity (LOH) with an average fractional allelic loss (FAL) of 49.9% of an aggregate of 2,378 informative markers. The level of FAL in the IPMNs (10%) was significantly lower than in the pancreatic adenocarcinomas. The most common locus of LOH in the IPMNs was at 19p (LOH at 24% of markers). The regions of frequent allelic loss observed in the familial pancreatic cancers were similar to those found in sporadic pancreatic cancers.

CONCLUSIONS

The allelic loss patterns of familial and sporadic pancreatic cancers and IPMNs provide clues as to the genomic locations of tumor suppressor genes inactivated in these neoplasms.

Large scale structure in Bekenstein's theory of relativistic modified Newtonian dynamics

A relativistic theory of modified gravity has been recently proposed by Bekenstein. The tensor field in Einstein's theory of gravity is replaced by a scalar, a vector, and a tensor field which interact in such a way to give modified Newtonian dynamics (MOND) in the weak-field nonrelativistic limit. We study the evolution of the Universe in such a theory, identifying its key properties and comparing it with the standard cosmology obtained in Einstein gravity. The evolution of the scalar field is akin to that of tracker quintessence fields. We expand the theory to linear order to find the evolution of perturbations on large scales. The impact on galaxy distributions and the cosmic microwave background is calculated in detail. We show that it may be possible to reproduce observations of the cosmic microwave background and galaxy distributions with Bekenstein's theory of MOND.

Design and synthesis of thiol containing inhibitors of matrix metalloproteinases

A series of thiol containing derivatives was prepared. Several of these compounds were found to inhibit matrix metalloproteinases 1, 3, and 9 with selectivity towards 3 and 9. Compounds 15, 20, and 22 were administered to rats orally at 75 mumol/kg. Drug levels of compounds 20 and 22 in the plasma were found to exceed the IC50 values for MMP 3 and 9 four hours after administration.

Aspiration to obtain osteoblast progenitor cells from human bone marrow: the influence of aspiration volume

Bone marrow contains osteoblast progenitor cells that can be obtained with aspiration and appear to arise from a population of pluripotential connective-tissue stem cells. When cultured in vitro under conditions that promote an osteoblastic phenotype, osteoblast progenitor cells proliferate to form colonies of cells that express alkaline phosphatase and, subsequently, a mature osteoblastic phenotype. We evaluated the number of nucleated cells in bone-marrow samples obtained with aspiration from the anterior iliac crest of thirty-two patients without systemic disease. There were nineteen male patients and thirteen female patients; the mean age was forty-one years (range, fourteen to seventy-seven years). The prevalence and concentration of the osteoblast progenitor cells also were determined, by placing the bone-marrow-derived cells into tissue-culture medium and counting the number of alkaline phosphatase-positive colony-forming units. In order to assess the effect of aspiration volume, two sequential experiments were performed. In the first experiment, aspiration volumes of one and two milliliters were compared. In the second experiment, aspiration volumes of two and four milliliters were compared. The mean prevalence of alkaline phosphatase-positive colony-forming units in the bone-marrow samples was thirty-six per one million nucleated cells (95 per cent confidence interval, 28 to 47); a mean of 2400 alkaline phosphatase-positive colony-forming units was obtained from a two-milliliter aspirate. There was a significant difference among the patients with respect to the number of alkaline phosphatase-positive colony-forming units in these bone-marrow samples (p < 0.001). Seventy per cent of this variation in the prevalence was due to variation among patients, and 20 per cent was due to variation among aspirates. The number of alkaline phosphatase-positive colony-forming units in the aspirate increased as the aspiration volume increased. However, contamination by peripheral blood also increased as the aspiration volume increased. An increase in the aspiration volume from one to four milliliters caused a decrease of approximately 50 per cent in the final concentration of alkaline phosphatase-positive colony-forming units in an average sample.

CLINICAL RELEVANCE

On the basis of these data, we recommend that, when bone marrow is obtained with aspiration for use as a bone graft, the volume of aspiration from any one site should not be greater than two milliliters. A larger volume decreases the concentration of osteoblast progenitor cells because of dilution of the bone-marrow sample with peripheral blood. We estimate that four one-milliliter aspirates will provide almost twice the number of alkaline phosphatase-positive colony-forming units as will one four-milliliter aspirate. In addition, these data confirm that humans differ significantly from one another with respect to the cellularity of bone marrow and the prevalence of osteoblast progenitor cells. Additional studies are necessary to determine if the number or prevalence of alkaline phosphatase-positive colony-forming units in bone marrow is a determining factor in the efficacy of an autogenous bone or bone-marrow graft and to ascertain how the number and function of alkaline phosphatase-positive colony-forming units may change as a function of factors such as age, menopausal status, and selected diseases.

Practical guide to the diagnosis of thalassemia. Council of Regional Networks for Genetic Services (CORN)

Thalassemias occur in individuals of all ethnic backgrounds and are among the most common genetic diseases worldwide. The diagnosis of thalassemia can easily be part of primary medical practice. Here we outline a practical approach to the detection of thalassemias in three common clinical settings. The first involves any patient with a low mean corpuscular volume (MCV) with or without anemia. The second is a neonatal screening result indicating possible presence of thalassemia. Finally, evaluation for thalassemia should be considered in the context of family planning or pregnancy in patients whose ethnicity indicates origin from high risk geographic areas. We also review the various types of the thalassemia syndromes and provide an overview of general therapeutic considerations.

Synthesis and structure-activity relationships of oxamic acid and acetic acid derivatives related to L-thyronine

Aryloxamic acids 7 and 23, (arylamino)acetic acids 29, arylpropionic acids 33, arylthioacetic acids 37, and (aryloxy)acetic acid 41 related to L-triiodothyronine (L-T3) were prepared and tested in vitro for binding to the rat liver nuclear L-T3 receptor and the rat membrane L-T3 receptor. The structure-activity relationships for these compounds are described, with 7f, 23a, 29c, 33a, 37b, and 41 showing excellent potency (IC50's of 0.19, 0.16, 1.1, 0.11, 3.5, and 0.10 nM, respectively) to the nuclear receptor and significantly lower binding affinity to the membrane receptor (IC50's > 5 microM). Some of these compounds, especially in the oxamic acid series 7 and 23, showed an unprecedented potency for methyl-substituted derivatives such as 7f and 23a. Compounds 7f and 23a showed good lipid lowering effects in rats with ED50's of 20 and 5 micrograms/kg po, respectively, and a lack of cardiac side effects in rats at doses as high as 10 and 25 mg/kg po, respectively.

The effects of X monosomy on brain development: monozygotic twins discordant for Turner's syndrome

Monosomy for the X chromosome is the most frequent cause of Turner's syndrome, a common clinical syndrome associated with particular physical and neurobehavioral features. The results from comprehensive assessment of prepubertal monozygotic female twins discordant for X monosomy are presented. Zygosity was established with DNA Fingerprinting and no evidence of chromosomal mosaicism was seen in either child. Physical features in the affected twin were relatively mild with respect to the full spectrum of physical malformations and disabilities associated with Turner's syndrome. The neurobehavioral phenotypes of the twins were compared. Although both sisters scored in the superior range of intelligence, the affected twin's Performance IQ was 18 points less than her sister, whereas Verbal IQ showed only a 3-point difference between the sisters. Other relative differences were noted within the executive, visuospatial, and visuomotor domains of function. Behavioral evaluation indicated greater problems with attention, hyperactivity, and anxiety in the affected twin. Quantitative analysis of brain anatomy revealed evidence of both general and regional effects of X monosomy on neurodevelopment. Cerebrospinal fluid volume was increased by 25% in the affected twin compared with her sister with a corresponding decrease in gray matter volume. The right frontal, right parietal-occipital, and left parietal-perisylvian regions showed the greatest discrepancy between the sisters with respect to increased cerebrospinal fluid and decreased gray matter volumes in twin with X monosomy. Differences in the posterior fossa were also noted with a 50% relative increase in the volumes of the fourth ventricle and cisterna magna and a 10 to 15% relative reduction in size of the cerebellar vermis, pons, and medulla in the affected twin. The association between the neurobehavioral and neuroanatomical findings in the affected twin is discussed. The unique nature of the naturally occurring genetic phenomenon seen in this twin pair provides an opportunity to more fully elucidate the neurobehavioral phenotype associated with X monosomy and Turner's syndrome.

Neurobehavioral effects of the fragile X premutation in adult women: a controlled study

Although previous studies have suggested that the fragile X premutation (fra [X] pM) does not cause deleterious effects, methodological constraints have prevented more definitive conclusions from being reached. In this report, we describe the neuropsychiatric and cognitive-neuropsychological status of 34 adult women with the fra (X) pM, as compared with a well-matched control group of 41 mothers of fra (X)-negative children with developmental disability. The results indicate that there are no meaningful differences between adult women with the fra (X) pM and control subjects with respect to cognitive abilities or profile, neuropsychological function, psychiatric diagnoses or symptoms, and self-rated personality profile. No measure for either group showed evidence of functioning outside the normal range except for a high lifetime prevalence of major depression in both groups. Additional exploratory analyses within the fra (X) group showed no significant effect of either the size of the fra (X) insert or X chromosome inactivation pattern in leukocytes, on any measure of neurobehavioral function. These findings provide additional information to professionals providing genetic counseling to, and assessment of, fra (X) families.

Usefulness of a CACA repeat polymorphism in genotype assignments in Duchenne/Becker muscular dystrophy

RFLP analysis in Duchenne/Becker muscular dystrophy (D/BMD) has been limited by the lack of informative marker loci at the 3' end of the dystrophin gene. Recently a CACA repeat polymorphism was described in the 3' untranslated end of the dystrophin gene which we have found helpful in genotype assignments of D/BMD families when an RFLP approach is required. The CACA repeat marker has 2 common alleles (1 and 2) that are easily visualized by a nonradioactive PCR method followed by polyacrylamide gel electrophoresis. We present 2 families which demonstrate the use of this polymorphism. Since 35-50% of females are heterozygous, this locus is a useful marker in RFLP analysis of D/BMD families.

Diagnosis of Duchenne and Becker muscular dystrophies by polymerase chain reaction. A multicenter study

OBJECTIVE--To assess the efficiency, reliability, and ease of use of DNA diagnosis for Duchenne and Becker muscular dystrophies (DMD/BMD) using the polymerase chain reaction (PCR). DESIGN--DNA from the patients was screened for deletion mutations using multiplex PCR, and the results were compared with those obtained by Southern blot analysis. The PCR multiplex reaction detects nine specific "hot-spot" exons in the dystrophin gene while the Southern analysis detects 66 specific dystrophin gene restriction fragments. The multiplex reaction requires 50-fold less DNA than Southern analysis and thus is considerably more sensitive. SETTING--Fourteen university-affiliated and private genetic disease diagnostic laboratories. PATIENTS--Male patients with clinical signs of DMD/BMD. Cases were selected for analysis randomly, without knowledge of whether a deletion was present within the dystrophin gene. MAIN OUTCOME MEASURES--The percentage of cases that were detectable by multiplex PCR in comparison with Southern analysis, the frequency, extent, and location of the detected deletion mutations. In some cases, duplication mutations were monitored. RESULTS--The accuracy of a single PCR multiplex amplification (nine exons) was compared with Southern analysis with 10 cDNA probes that cover the full length of the gene. The multiplex PCR analytic method detected 82% of those deletions detected by Southern analysis methods. In one of 745 analyses, the multiplex method suggested a single exon deletion, which was not confirmed by Southern analysis, representing a false-positive rate of 0.013%. CONCLUSIONS--Multiplex PCR represents a sensitive and accurate method for deletion detection of 46% of all cases of DMD/BMD. The method requires 1 day for analysis, is easy to perform, and does not use radioactive tracers. As such, multiplex PCR represents an efficient and rapid method for prenatal or postnatal diagnosis of DMD/BMD.

In utero fetal muscle biopsy for the diagnosis of Duchenne muscular dystrophy

Deoxyribonucleic acid techniques can be used to diagnose Duchenne muscular dystrophy prenatally in male fetuses that are at risk. Deoxyribonucleic acid-based prenatal diagnosis can be impossible when there is only one prior affected male and there is no identifiable deletion or alteration. We performed fetal muscle biopsy in utero in such a case and documented the presence of dystrophin, thereby confirming normality in a male fetus at risk. This first in utero experience adds fetal muscle biopsy to the available procedures for fetal tissue diagnosis.

242 breakpoints in the 200-kb deletion-prone P20 region of the DMD gene are widely spread

Using whole cosmids as probes, we have mapped 242 DMD/BMD deletion breakpoints located in the major deletion hot spot of the DMD gene. Of these, 113 breakpoints were mapped more precisely to individual restriction enzyme fragments in the distal 80 kb of the 170-kb intron 44. An additional 12 breakpoints are distributed over the entire region, with no significant local variation in frequency. Furthermore, deletion sizes vary and are not influenced by the positions of the breakpoints. This argues against a predominant role of one or a few specific sequences in causing frequent rearrangements. It suggests that structural characteristics or a more widespread recombinogenic sequence makes this region so susceptible to deletion. Our study revealed several RFLPs, one of which is a 300-bp insertion/deletion polymorphism. Abnormally migrating junction fragments are found in 81% of the precisely mapped deletions and are highly valuable in the diagnosis of carrier females.

Alpha-thalassemia: prenatal diagnosis and neonatal implications

Homozygous alpha-thalassemia major, or Bart's hemoglobinopathy, is the most common etiology of nonimmune hydrops in those of Oriental descent. The prenatal diagnosis can now be made utilizing DNA hybridization technique from fetal cells obtained by either amniocentesis or chorionic villus sampling. A case is reviewed documenting the utilization of DNA studies in managing patients known or suspected to have a history of alpha-thalassemia major.

Cardiac beta-adrenoceptor binding characteristics with age following adrenal demedullation

1. The role of adrenal medullary catecholamines in the regulation of cardiac function becomes more important when adrenergic neural influences in the heart are decreased. Since adrenergic nervous input to the heart decreases with age, it would be expected that catecholamine influence on cardiac neuroeffector junction would increase. 2. Fischer-344 rats of 6-, 12- and 24-months were adrenal demedullated or sham-operated and the animals were killed at the end of two weeks. beta-Adrenoceptors were studied in the membrane preparations from the ventricles of rat hearts. [125I]-iodopindolol was used as the radioligand. The density of beta-receptors (Bmax), dissociation constant (KD) and the ratio of cardiac beta-adrenoceptor subtypes were studied. The relative percentages of beta-receptor subtypes were determined by use of ICI 89,406 (beta 1-selective antagonist) and ICI 118,551 (beta 2-selective antagonist). 3. In 24-month-old animals which were adrenal demedullated, hydrocortisone replacement was employed for one week; the animals were killed one week later. 4. The data indicate that there was a diminution of the Bmax following adrenal demedullation at all ages but that the ratios of beta 1: beta 2-adrenoceptors remain the same as in the controls (67:33). The effect of adrenal medullary catecholamines on cardiac beta-receptor binding characteristics did not seem to be influenced by age.

A genetic linkage map of five marker loci in and around the Duchenne muscular dystrophy locus

Linkage analysis of five marker loci in and around the Duchenne muscular dystrophy (DMD) locus, DXS84, DXS206, DXS164, DXS270, and DXS28, was conducted with 499 families. Overall, the best multipoint distances were found to be DXS84-3.7 +/- 0.6 cM-DXS206-1.0 +/- 0.4 cM-DXS164-1.9 +/- 0.6 cM-DXS270-12.0 +/- 1.1 cM-DXS28. A comparison of this linkage map with the established physical map suggests the presence of hot spots for recombination in the DMD locus.

CPP, a selective N-methyl-D-aspartate (NMDA)-type receptor antagonist: characterization in vitro and in vivo

3-(2-Carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) was synthesized as a rigid analog of 2-amino-7-phosphonoheptanoate, a previously known antagonist at the N-methyl-D-aspartate (NMDA) preferring, or NMDA-type, of excitatory amino acid receptor. CPP was found to be a potent, selective and competitive antagonist of NMDA-type receptors. CPP antagonized with an IC50 of 8 muM [3H]ACh release which was evoked from rat striatal brain slices by NMDA (50 muM). In contrast, the release of [3H]ACh evoked by elevated KCI was not inhibited by CPP even at a concentration of 100 muM. The antagonism by CPP of NMDA-evoked [3H]ACh release was competitive, with a pA2 of 5.66 for CPP, compared with a pA2 value of 5.22 for 2-amino-7-phosphonoheptanoate. CPP affected neither the uptake of L-[3H]glutamate nor the inhibition by aconitine of L-[3H]glutamate uptake, suggesting a lack of membrane-stabilizing or local anesthetic effects, and also suggesting that CPP itself may not be taken up through the L-glutamate membrane transporter. Moreover, [3H] CPP was not accumulated by synaptosomes (P2 fraction) which avidly accumulate L-[3H]glutamate, supporting the concept that this NMDA-type receptor antagonist acts at an NMDA-type receptor on the external surface of the plasma membrane. CPP (10 muM) failed to interact with any of 21 other putative neurotransmitter receptors including alpha-[3H]amino-3-hydroxy-5-methylisoxazole-4-propionic acid binding (quisqualate-type receptor) and [3H]kainate binding (kainate-type receptor). Audiogenic convulsions in DBA/2 mice were blocked by CPP (ED50 = 1.5 mg/kg i.p.) as were NMDA-induced seizures in CF-1 mice (ED50 = 1.9 mg/kg i.p.). In both strains, CPP impaired the traction reflex at higher doses (ED50 = 6.8 mg/kg and 6.1 mg/kg and 6.1 mg/kg i.p. for DBA/2 and CF-1, respectively). The traction reflex impairment by CPP may be due to muscle relaxant effects of the compound, an explanation supported by the finding that CPP reduced muscle tone as assessed by electromyogram measurement in animals whose muscle tone had been increased by opiate administration. Finally, cerebellar cyclic GMP levels, known to be sensitive to neurotransmission via NMDA-type receptors, were decreased by CPP (ED50 = 4.7 mg/kg i.p.) in mice. In conclusion, based upon the competitive antagonism by CPP of NMDA-evoked [3H] ACh release in vitro and the antagonism of NMDA-induced convulsions in vivo, the data presented are consistent with competitive antagonism of NMDA-type receptors.

Binding of [3H]3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid to rat brain membranes: a selective, high-affinity ligand for N-methyl-D-aspartate receptors

3-(2-Carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP), a rigid analog of 2-amino-7-phosphonoheptanoic acid, has been reported as a selective N-methyl-D-aspartate (NMDA) antagonist. [3H]CPP bound with relatively high affinity (Kd = 201 nM) to Triton-treated rat brain crude synaptic membranes using a centrifugation assay. Binding was saturable, reversible, heat sensitive and dependent on protein concentration. Specific binding, which represented 75 to 85% of the total counts bound, was enriched in synaptosomal and microsomal fractions of rat brain, suggesting an involvement in events related to synaptic transmission. On a regional basis, binding was highest in hippocampus, followed by cortex greater than striatum greater than cerebellum = thalamus. No specific binding could be detected in pons medulla or in liver, kidney, heart, lung and adrenal tissue. [3H]CPP binding was stereoselective for the isomers of glutamate, 2-amino-5-phosphonopentanoic acid, homocysteic acid, alpha-aminoadipic acid and N-methyl-aspartate. The most potent compounds tested were L-glutamate and CPP, which were equiactive in displacing [3H]CPP. The order of activity of other excitatory amino acid receptor ligands was D-2-amino-5-phosphonopentanoic acid greater than L-homocysteic acid greater than or equal to DL-2-amino-7-phosphonoheptanoic acid = D-aspartate = L-aspartate greater than L-serine-O-sulfate = D-alpha-aminoadipic acid = ibotenate greater than NMDA greater than DL-2-amino-6-phosphonohexanoic acid greater than quisqualate greater than N-methyl-L-aspartate. The quisqualate- and kainate-type receptor agonists DL-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate and kainic acid, respectively, had negligible activity at 100 microM.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac hypertrophy in chick embryos induced by hypothermia

A decrease in incubation temperature from 38 to 32 degrees C elicits a decrease in chicken embyro size and weight with concomitant heart enlargement if done after day 10 of incubation. When assayed at day 18 of incubation with the hypothermia started on day 11 or 14, evidence is presented that the heart enlargement is an hypertrophy with no detectable hyperplasia. Supporting data are presented for various physical parameters showing increases in heart wet and dry weight, volume, area, wall thickness, and cell size. There was little difference in DNA content and nuclear [3H]thymidine labeling index between hearts of control and hypothermic embryos. Hearts of hypothermic embryos showed a slight increase in water content and considerable increases in RNA, protein, and glycogen content per unit DNA. The average size of polysomes isolated from hypothermic hearts was larger than that of polysomes isolated from controls. Microscopic studies showed no obvious increase in amount of capillary beds, connective tissue, and myocardial cells. Annulate lamellae were found only in myocardial cells of hypothermic embryos in sparse amounts and low frequency but always associated with large deposits of glycogen.

Analysis of deletions in DNA from patients with Becker and Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disorder for which the biochemical defect is as yet unknown. Recently, two cloned segments of human X-chromosome DNA have been described which detect structural alterations within or near the genetic locus responsible for the disorder. Both of these cloned segments were described as tightly linked to the locus and were capable of detecting deletions in the DNA of boys affected with DMD. In an attempt to determine more precisely the occurrence of these deletions within a large population of DMD patients and the accuracy of one of the segments, DXS164 (pERT87), in determining the inheritance of the DMD X chromosome, the subclones 1, 8 and 15 were made available to many investigators throughout the world. Here we describe the combined results of more than 20 research laboratories with respect to the occurrence of deletions at the DXS164 locus in DNA samples isolated from patients with DMD and Becker muscular dystrophy (BMD). The results indicate that the DXS164 locus apparently recombines with DMD 5% of the time, but is probably located between independent sites of mutation which yield DMD. The breakpoints of some deletions are delineated within the DXS164 locus, and it is evident that the deletions at the DMD locus are frequent and extremely large.

Prenatal diagnosis of hemoglobinopathies by DNA analysis

Restriction site polymorphisms are normal inherited variations in DNA that can be readily detected by restriction endonuclease analysis. Currently, 17 such polymorphisms are recognized within a 60 kb (kilobase) stretch of DNA which includes the beta-globin gene complex. Because of their proximity to the beta-globin gene, often these restriction site polymorphisms can be used to predict inheritance of beta-globin variants that produce disease. For example, restriction site polymorphisms can be used for prenatal diagnosis for the large majority of couples at risk of having a child with beta-thalassemia. When each member of such a couple is heterozygous at one or more of these 17 sites, family studies are usually successful in determining which forms of the polymorphism are co-inherited with the beta-thalassemia genes in that particular family. Subsequently, study of fetal DNA isolated from amniocytes obtained by midtrimester amniocentesis or from chorionic villi obtained by first trimester chorion biopsy will reveal which DNA polymorphisms that fetus has inherited. By deductive reasoning one can then predict which beta-globin genes it has co-inherited. Because of the general nature of these polymorphisms, which are related to the beta-globin gene and its variants only because of their proximity on chromosome 11, they are potentially useful in the prenatal diagnosis of any beta-chain hemoglobinopathy. Some hemoglobinopathies (including alpha-thalassemia, sickle cell anemia, and some cases of beta-thalassemia) can be detected directly by DNA analysis. In these cases in utero diagnosis does not need to rely on restriction site polymorphisms, which require preliminary family studies and are not applicable in all at risk pregnancies. Recently, genetic probes, which are necessary for detecting restriction site polymorphisms, have been isolated for sequences of several genes whose protein products are important in blood coagulation. These include probes for all three genes whose polypeptide products combine to form the fibrinogen molecule as well as probes for the prothrombin, Factor IX, Factor VIII, and antithrombin III genes. Defects in these genes are expected to be the causes of afibrinogenemia, prothrombin deficiency, hemophilia B, hemophilia A, and antithrombin III deficiency, respectively. From experience with other genes, it is expected that restriction site polymorphisms within and/or flanking these genes will be found.(ABSTRACT TRUNCATED AT 400 WORDS)

Sugar transport and potassium permeability in yeast plasma membrane vesicles

Plasma membrane vesicles were isolated from homogenised yeast cells by filtration, differential centrifugation and aggregation of the mitochondrial vesicles at pH 4. As judged by biochemical, cell electrophoretic and electron microscopic criteria a pure plasma membrane vesicle preparation was obtained. The surface charge density of the plasma membrane vesicles is similar to that of intact yeast cells with an isoelectric point below pH 3. The mitochondrial vesicles have a higher negative surface charge density in the alkaline pH range. Their isoelectric point is near pH 4.5, where aggregation is maximal. The yield of vesicles sealed to K+ was maximal at pH 4 and accounted for about one third of the total vesicle volume. The plasma membrane vesicles demonstrate osmotic behaviour, they shrink in NaCl solutions when loosing K+. As in intact yeast cells the entry and exit of sugars like glucose or galactose in plasma membrane vesicles is inhibited by UO22+. Counter transport in plasma membrane vesicles with glucose and mannose and iso-counter transport with glucose suggests that a mobile carrier for sugar transport exists in the plasma membrane. After galactose pathway induction in the yeast cells and subsequent preparation of plasma membrane vesicles the uptake of galactose into the vesicles increased by almost 100% over the control value without galactose induction. This increase is explained by the formation of a specific galactose carrier in the plasma membrane.

Yeast plasma membrane vesicles suitable for transport studies

Isolated yeast plasma membrane vesicles demonstrate a permeability barrier toward K(+) and glucose. Influx and efflux of glucose are inhibited by UO(2) (2+) ions.