Genomic organization and precise physical location of protein phosphatase 2A regulatory subunit A beta isoform gene on chromosome band 11q23.

Protein phosphatase 2A (PP2A) holoenzyme plays a critical role in cell-cycle control and growth-factor signaling, and is implicated in tumorigenesis. Because the protein phosphatase 2 regulatory subunit A beta isoform gene (PPP2R1B) maps within the critical region of hereditary paraganglioma (PGL1) on chromosomal band 11q23, we characterized its genomic structure and evaluated it as a candidate gene for PGL1. PPP2R1B has 15 exons spanning approx. 27kb genomic distance. We placed the exons on genomic EcoRI fragments and identified their flanking intronic sequences. The gene was oriented from telomere to centromere. Splice acceptor and donor sites of all introns conformed to the GT/AG rule. Northern analysis with a cDNA probe identified 2.5kb and 5.0kb transcript sizes. We identified an ATG initiation codon in a favorable context and mapped two transcription start sites 15bp and 66bp upstream of it. We also mapped a 3'-polyadenylation site 504bp downstream of the TGA stop codon, consistent with the 2.5kb transcript size. We did not detect germ-line mutations by single-stranded conformational polymorphism (SSCP) analysis or major rearrangements by Southern analysis in a set of PGL1 patients. In conclusion, we precisely mapped and characterized the structure of PPP2R1B and evaluated it as a candidate gene for PGL1.

Bipolar affective disorder partially cosegregates with a balanced t(9;11)(p24;q23.1) chromosomal translocation in a small pedigree.

Analysis of an extended pedigree in which a balanced t(9;11)(p24;q23.1) translocation was found to cosegregate with bipolar affective disorder revealed that five of 11 translocation carriers had bipolar affective disorder and one carrier had unipolar depression. There were no affected individuals in the pedigree without the balanced translocation. We hypothesized that gene(s) or gene regulatory regions disrupted by the translocation might be contributing to the bipolar affective disorder in a dominant fashion. To test this hypothesis, we isolated the derivative chromosome 9 and derivative chromosome 11 in somatic cell hybrids and identified the nearest flanking markers on chromosome 9 (D9S230 and D9S2011E/HRFX3) and chromosome 11 (EST00652 and CRYA2). YAC contigs were constructed in the region of flanking markers for both chromosomes 9 and 11. Chromosome 11 breakpoint was localized within an 8-kb region in a small insert (100 kb) YAC. Chromosome 9 breakpoint was localized within approximately 2 Mb region. Several genes and ESTs including EST00652, CRYA2, DRD2, 5HTR3 on chromosome 11 and VLDLR and SLC1A1 on chromosome 9 were mapped within the vicinity of the breakpoint but were shown not to be disrupted by the translocation breakpoint. Although several possibilities exist regarding the role of the balanced translocation in developing bipolar affective disorder in this pedigree, including a chance cosegregation, identification of a disrupted gene or gene regulatory region with the help of physical mapping resources described in this study may help to identify the presence of a susceptibility gene for this disorder.

Effect of intrinsic sympathomimetic activity on the ability of hypertensive patients to derive a cardiorespiratory training effect during chronic beta-blockade.

The effect of intrinsic sympathomimetic activity (ISA) on the ability of patients with high blood pressure (BP) to derive a cardiorespiratory training effect during long-term beta-blocker therapy was studied. Fifty sedentary hypertensive subjects were randomly assigned to propranolol (n = 23) or pindolol (n = 27) therapy for a 22 week double-blind parallel study. Over the first 2 weeks, during which subjects remained sedentary, drug doses were titrated to produce equipotent, clinically significant BP reductions. Subjects subsequently continued drug therapy and completed 20 weeks of exercise training. Although pindolol tended to preserve submaximal exercise heart rates to a greater degree than propranolol, the initial 2 weeks of drug therapy resulted in equivalent reductions in maximal oxygen uptake with propranolol (6% reduction) and pindolol (8% reduction). Likewise, 20 weeks of training induced similar, statistically significant (P = .0001) increases in maximal oxygen uptake during propranolol (10% increase) and pindolol (11% increase) treatment. We therefore conclude that ISA does not confer any advantage to patients with high BP who receive chronic beta-blocker therapy and wish to improve their cardiorespiratory fitness by participating in exercise training.

Comparison of diclofenac sodium and aspirin in the treatment of acute sports injuries.

A randomized, double-blind, parallel-group clinical trial compared diclofenac sodium (Voltaren, Ciba-Geigy Summit, NJ) with aspirin for the treatment of acute sprains and/or strains of the knee or ankle. One hundred thirty-nine patients were admitted to the study. Patients received either 150 mg (75 mg twice daily) of diclofenac (N = 69) or 3.6 g (1.2 g three times daily) of aspirin (N = 70) for 3 to 10 days. Forty-seven diclofenac patients and 49 aspirin patients, mean age for both groups 25 years, were evaluated to determine the efficacy of each treatment. Both groups experienced significant (P less than 0.001) improvements for all efficacy variables measured. Treating sprains and strains with diclofenac rather than with aspirin allowed an earlier return to activity. Of those patients who achieved playing fitness, those in the diclofenac group resumed athletic activities in a mean of 4.7 days, compared with a mean of 5.9 days for patients in the aspirin group. Although the overall multivariate F was nonsignificant (P = 0.19), the univariate F for days required to resume playing fitness was significantly (P = 0.025) shorter in the diclofenac group. While the nonsignificant multivariate result suggests that the significance may be due to chance, it is also possible that there was a trend toward earlier resumption of activities with diclofenac treatment compared to aspirin, but an insufficient sample size to demonstrate the trend statistically. Since others have reported such a trend without the greater controls of a multivariate analysis, this area warrants further research.

A high-resolution STS, EST, and gene-based physical map of the hereditary paraganglioma region on chromosome 11q23.

The genes responsible for hereditary paragangliomas (glomus tumors, MIM No. 168000) have been mapped to two distinct loci on the long arm of chromosome 11. Most of the informative families appear to be linked to the distal locus on chromosome 11q23 (PGL1), which has been previously confined to a 2-cM interval by haplotype analysis in an extended Dutch pedigree. To facilitate the identification of the PGL1 disease gene, we constructed an approximately 4-Mb ordered clone contig map of Sequence tagged sites, expressed sequence tags (ESTs), and known genes that spans the PGL1 critical region on chromosome 11q23. Among 29 new positional candidate ESTs, only two (EST100999 and EST241777) mapped within the PGL1 critical region. We further characterized the genomic organization of the promyelocytic leukemia zinc finger (PLZF) gene that maps within the PGL1 critical region and physically excluded the serotonin receptor type 3 (5HT3R) gene. Finally, we identified a common, silent, single-base substitution polymorphism in the 5HT3R gene and characterized the allele sets of two new highly polymorphic microsatellite repeats within the PGL1 critical region.

The effects of aerobic exercise on plasma catecholamines and blood pressure in patients with mild essential hypertension.

The effects of a 16-week aerobic exercise program on blood pressure and plasma catecholamine levels were evaluated in 56 patients with baseline diastolic blood pressure of 90 to 140 mm Hg. The exercise group significantly improved their physical fitness, and reduced systolic and diastolic blood pressures, compared with controls. To evaluate the relationship between exercise, blood pressure, and plasma catecholamine values, the exercise group was further divided into hyperadrenergic and normoadrenergic subgroups. Reductions in systolic pressures were 6.3 mm Hg, 10.3 mm Hg, and 15.5 mm Hg for control, normoadrenergic, and hyperadrenergic groups, respectively. Diastolic changes were similar and also significant. Within the hyperadrenergic group, changes in blood pressures were associated with changes in values for plasma catecholamines following training. We conclude that an aerobic exercise program reduces blood pressure, which is at least partially mediated by changes in plasma catecholamine levels.

A radiation hybrid map of 95 STSs spanning human chromosome 13q.

We have constructed a high-resolution physical map of the long arm of human chromosome 13 using a panel of 94 radiation hybrids. A comprehensive map of 95 chromosome 13-specific sequence tagged sites (STSs) spanning 13q from the presumed centromere at D13Z1 to the known telomere was obtained by multipoint maximum likelihood statistical methods. The 95 markers have an average retention frequency of 10%, with markers closer to the centromere having much greater retention frequencies (22-49%) than distal 13q markers (2-12%). The most likely radiation hybrid map localized the 95 STSs into 54 unique map positions, 34 with odds of 1000:1 or greater; the comprehensive map localized all but 17 STSs with odds exceeding 10:1. The total map length of 13q was 1302 cR9000 (range 6.4-94.4 cR9000) and a physical distance of 98 Mb, so that 1% breakage in the RH panel corresponds to 75 kb. A comparison of the comprehensive RH map to genetic maps of chromosome 13q shows identical locus orders for the common markers, with two exceptions over 1-cM distances. We discuss the possible relationships between the genetic and the radiation hybrid maps.

Fine mapping of the split-hand/split-foot locus (SHFM3) at 10q24: evidence for anticipation and segregation distortion.

Split-hand/split-foot malformation (SHFM, ectrodactyly, or lobster-claw deformity) is a human limb malformation characterized by aberrant development of central digital rays with absence of fingers and toes, a deep median cleft, and fusion of remaining digits. SHFM is clinically heterogeneous, presenting both in an isolated form and in combination with additional abnormalities affecting the tibia and/or other organ systems, including the genitourinary, craniofacial, and ectodermal structures. Three SHFM disease loci have been genetically mapped to chromosomes 7q21 (SHFM1), Xq26 (SHFM2), and 10q24 (SHFM3). We mapped data from a large Turkish family with isolated SHFM to chromosome 10q24 and have narrowed the SHFM3 region from 9 cM to an approximately 2-cM critical interval between genetic markers D10S1147 and D10S1240. In several instances we found evidence for a more severe phenotype in offspring of a mildly affected parent, suggesting anticipation. Finally, data from this family, combined with those from six other pedigrees, mapped to 10q24, demonstrate biased transmission of SHFM3 alleles from affected fathers to offspring. The degree of this segregation distortion is obvious in male offspring and is possibly of the same magnitude for female offspring.

Repositioning the hereditary paraganglioma critical region on chromosome band 11q23.

Hereditary paragangliomas (PGL, glomus tumors, MIM no.168000) are mostly benign, slow-growing tumors of the head and neck region. The gene (or genes) affecting risk to PGL are subject to genomic imprinting: children of affected fathers exhibit an autosomal dominant pattern of disease inheritance, whereas children of affected mothers rarely if ever develop the disease through maternal transmission. We previously confined the disease gene to an approximately 6 Mb critical region on chromosome band 11q23 (PGL1). Based on haplotype analysis of an extended Dutch pedigree, a 2 Mb sub-region between D11S938 and D11S1885 was proposed as the PGL1 critical interval. In this study, we excluded this interval by analysis of two new single tandem repeat polymorphisms (STRP) contained therein. Instead, we predicted a non-overlapping, more proximal 2 Mb critical interval between D11S1647 and D11S897, and evaluated this new region using nine STRP (D11S1986, five new, closely-linked STRP, D11S1347, D11S3178, and D11S1987). Consistent with our prediction, we observed substantial haplotype-sharing within the Dutch pedigree. We also analyzed four new American PGL families. A recombination event detected in one family further defined D11S1347 as the new telomeric border. We observed significant haplotype-sharing within this new interval among three unrelated American PGL families, strongly suggesting that they originated from a common ancestor. Thus, we confined PGL1 to an approximately 1.5 Mb region between D11S1986 and D11S1347, and showed identity-by-descent sharing for a group of American PGL families.

Rapid construction of integrated maps using inner product mapping: YAC coverage of human chromosome 11.

Inner product mapping (IPM) has been proposed as a hybridization-based method for achieving low-cost, high-throughput, high-resolution radiation hybrid (RH) mapping of clones. Using Alu-PCR products of chromosome 11-specific clones, we serially hybridized a set of RHs against gridded filters of YACs having an average size of 350 kb. We then combined these hybridization data with preexisting RH map data to build an inner product map. This binning of 865 YACs provides the first high-resolution large-scale (> twofold redundancy) clonal coverage of human chromosome 11 and is the first inner product map ever constructed. We verified the accuracy and precision of this chromosome 11 map by performing a novel likelihood analysis on independent YAC hybridization data. These results establish that IPM is a highly rapid, inexpensive, accurate, and precise large-scale long-range mapping method, particularly when preexisting RH maps are available, and that IPM can replace or complement more conventional short-range mapping methods. IPM may enable the rapid construction of sequence-ready maps and the binning of expressed sequences.

Fine mapping of an imprinted gene for familial nonchromaffin paragangliomas, on chromosome 11q23.

Hereditary nonchromaffin paragangliomas (PGL; glomus tumors; MIM 168000) are mostly benign, slow-growing tumors of the head and neck region, inherited from carrier fathers in an autosomal dominant fashion subject to genomic imprinting. Genetic linkage analysis in two large, unrelated Dutch families assigned PGL loci to two regions of chromosome 11, at 11q23 (PGL1) and 11q13.1 (PGL2). We ascertained a total of 11 North American PGL families and confirmed maternal imprinting (inactivation). In three of six families, linkage analysis provided evidence of linkage to the PGL1 locus at 11q23. Recombinants narrowed the critical region to an approximately 4.5-Mb interval flanked by markers D11S1647 and D11S622. Partial allelic loss of strictly maternal origin was detected in 5 of 19 tumors. The greatest degree of imbalance was detected at 11q23, distal to D11S1327 and proximal to CD3D. Age at onset of symptoms was significantly different between fathers and children (Wilcoxon rank-sum test, P < .002). Affected children had an earlier age at onset of symptoms in 39 of 57 father-child pairs (chi2 = 7.74, P < .006). However, a more conservative comparison of the number of pairs in which a child had > or = 5 years earlier age at onset (n = 33) vis-a-vis that of complementary pairs (n = 24) revealed no significant difference (chi2 = 1.42, P > .2). Whether these data represent genetic anticipation or ascertainment bias can be addressed only by analysis of a larger number of father-child pairs.