Clinical diagnosis of heterozygous dystrophin gene deletions by fluorescence in situ hybridization

Two-thirds of patients affected by Duchenne or Becker muscular dystrophy (DMD/BMD) carry large intra-genic deletions in the dystrophin gene. In males, the deletions can be efficiently detected using multiplex polymerase chain reaction (PCR) and Southern blotting. In contrast, deletion detection in carrier females is complicated by the presence of a normal gene copy on the second X-chromosome. We have analyzed the boundaries of 570 deletions and 34 duplications in the dystrophin gene identified in the São Paulo and Leiden diagnostic laboratories. The data were used to select an optimal set of cosmid probes for the detection of the most frequently deleted areas of the dystrophin gene. Six cosmids were evaluated in fluorescence in situ hybridization (FISH) experiments to assess deletions in 21 heterozygous deletion-carriers and nine controls. No discrepancy was found between the FISH analysis and the molecular data, demonstrating the accuracy of the technique for carrier detection in Duchenne and Becker muscular dystrophy.

Chromosomal instability in fibroblasts and mesenchymal tumors from 2 sibs with Rothmund-Thomson syndrome

Rothmund-Thomson syndrome (RTS) is a rare autosomal recessive genodermatosis associated with increased risk of mesenchymal tumors. The putative gene has been provisionally assigned to chromosome 8. Using a cytogenetic-molecular approach, we studied lymphocytes, fibroblasts, osteosarcoma (OS) and malignant fibrous histiocytoma (MFH) from 2 affected fraternal twins, looking for constitutive markers of chromosome instability and tumor chromosomal changes which might reflect the common genetic background. The rate of spontaneous chromosome aberrations was not increased in lymphocytes. Conversely, karyotyping of primary fibroblasts from one sib evidenced chromosome breaks and both numerical and structural chromosome changes in 24% and 17% of the metaphases respectively. FISH of a 8q21.3 cosmid allowed us to detect trisomy of the target region on 7% of fibroblast nuclei from both sibs, 47% and 12% of OS and MFH cells. Pronounced chromosomal instability and clonal rearrangements leading to different chromosome-8 derivatives were detected in both tumors. CGH experiments showed multiple gains/losses, among which del(6q), also revealed by cytogenetics, and 7p gain were common, whereas 8q amplification was present only in OS. Chromosomal instability, observed in fibroblasts from the RTS patients studied, accounts for the increased risk of mesenchymal tumors in these patients.

Comparative genomic hybridization with lissamine- and fluorescein-labeled nucleotides

Biotin deoxyuridine 5'-triphosphate (dUTP) and digoxigenin dUTP are the labels most commonly used in comparative genomic hybridization (CGH). The relative infrequent use of direct fluorochrome-labeled nucleotides in CGH is related to the lower sensitivity they provide. Here we report the evaluation of two fluorochrome-conjugated nucleotides that have not been previously used in CGH (lissamine-5-dUTP and fluorescein-N6dATP) and show that this direct label combination performs at least as well as the indirect biotin/digoxigenin pair.

Skin cancer prevention counseling by pharmacists: specific outcomes of an intervention trial

The purpose of this study was to evaluate the effects of an intervention on pharmacists' behaviors, knowledge, and attitudes related to skin cancer prevention counseling. Fifty-four pharmacy sites (N = 178 pharmacists) were randomly assigned to the intervention or control condition. Intervention consisted of video-based training, prompts installed in the pharmacy to promote pharmacist-patient discussions on the topic, and group-based feedback on previous week's counseling rates. Outcomes were measured using a mailed survey. The proportion of patients counseled at post-test was significantly higher among intervention subjects, adjusting for pretest values. Similar results were found for pharmacists' skin cancer knowledge and self-rated expertise, but not for counseling-related attitudes. The intervention was successful. If implemented on a wide scale, large segments of the U.S. population would be exposed to skin cancer prevention advice.

Promoting skin cancer prevention counseling by pharmacists

OBJECTIVES

This study evaluated the effects of an intervention on rates of skin cancer prevention counseling by pharmacists.

METHODS

Fifty-four pharmacies were randomly assigned to intervention or control conditions. Intervention consisted of training, feedback, and prompts. Counseling rates before and after the intervention were obtained from study confederates.

RESULTS

At pretest, the proportions of control and intervention sites providing counseling at least once were 7.4% and 0%, respectively (NS). At posttest, these proportions were 3.7% and 66.7%, respectively (P < .001).

CONCLUSIONS

The results indicated that the intervention was successful and that pharmacists can play an important role in educating the public about skin cancer prevention strategies.

Identification of the critical region of 12p over-representation in testicular germ cell tumors of adolescents and adults

Cytogenetically, testicular germ cell tumors of adolescents and adults (TGCTs) are characterized by gain of 12p-sequences, most often through isochromosome formation (i(12p)). Fluorescence in situ hybridization (FISH) has shown that i(12p))-negative TGCTs also cryptically contain extra 12p-sequences. The consistency of 12p-over-representation in all histological subtypes of TGCTs, including their preinvasive stage, suggests that gain of one or more genes on 12p is crucial in the development of this cancer. So far, studies aimed at the identification of the relevant gene(s) were based on the 'candidate-gene approach'. No convincing evidence in favor of or against a particular gene has been reported. We combined conventional karyotyping, comparative genomic hybridization, and FISH to identify TGCTs with amplifications of restricted regions of 12p. Out of 49 primary TGCTs (23 without i(12p), 13 with and 13 unknown), eight tumors (six without i(12p) and two unknown) showed amplifications corresponding to 12p11.1-p12.1. Using bicolour-FISH, physical mapping, and semi-quantitative polymerase chain reactions, the size of the shortest region of overlap of amplification (SROA) was estimated to be between 1750-3000 kb. In addition, we mapped a number of genes in and around this region. While fourteen known genes could be excluded as candidates based on their location outside this region, we demonstrate that KRAS2, JAW1 and SOX5 genes are localized within the SROA. While KRAS2 and JAW1 map to the proximal border of the SROA, SOX5 maps centrally in the SROA. KRAS2 and JAW1 are expressed in all TGCTs, whereas one 12p amplicon-positive TGCT lacks expression of SOX5. The critical region of 12p over-represented in TGCTs is less than 8% of the total length of the short arm of chromosome 12. It will be helpful in the identification of the gene(s) involved in TGCT-development.

Exposure of workers to 2,3,7,8-substituted polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) compounds in sawmills previously using chlorophenol-containing antistain agents

The use of chlorophenol-containing antistain agents (e.g., Ky5, a wood preservative) ceased in Finland at the end of the 1980s, after 5 decades of use. Exposure of workers to the impurities in these agents (i.e., polychlorinated dibenzo-p-dioxins [PCDDs] and dibenzofurans [PCDFs]) was assessed at three sawmills at which personnel used a sodium chlorophenate product as an antistain agent. Given that compounds accumulate in body fat and their half-lives in humans are long, we could determine 2,3,7,8-substituted PCDDs and PCDFs 5-9 y after the last exposure occurred. We used high-resolution gas chromatography/high-resolution mass spectrometry to determine PCDDs/PCDFs in plasma from 39 Ky5-exposed workers and 18 nonexposed workers. The average total plasma concentration of PCDD/PCDF of the Ky5-exposed workers at the three sawmills were 1018, 945, and 1165 pg/g fat, and corresponding concentrations in the nonexposed workers were 743, 1124, and 844 pg/g fat, respectively. We found no significant differences in total levels between Ky5-exposed workers and nonexposed workers. However, concentrations of the 1,2,3,4,6,7,8-HpCDF isomer were significantly higher (p < .01) among the Ky5-exposed workers at all three sawmills (averages of 224, 99, and 148 pg/g fat) than among their respective nonexposed workers (averages of 43, 48, and 44 pg/g fat). These results indicate that workers had handled Ky5. When we expressed concentration levels in international toxic equivalents (I-TEQs), the mean total I-TEQ PCDD/PCDF of Ky5-exposed workers was significantly lower at one of the sawmills (average = 42 pg I-TEQ/g) than at the other two sawmills (averages of 64 and 62 pg I-TEQ/g)(p < .05). Nevertheless, total concentrations at the sawmills studied were within the range of background levels in the general population.

Improvement of mild sleep-disordered breathing with CPAP compared with conservative therapy

The aim of this randomized controlled trial was to assess the effects of treatment with continuous positive airway pressure versus conservative therapy (CT) on well-being, mood, and functional status in subjects with mild sleep-disordered breathing (SDB). One hundred and eleven subjects, aged 25 to 65 yr, with a respiratory disturbance index (RDI) of 5 to 30 and without subjective pathologic sleepiness, were randomized to nasal CPAP or to CT. Ninety-seven subjects were followed-up after 8 wk. Treatment response was assessed from changes between baseline and follow-up measures of mood, energy/fatigue, and functional status/general health. Of the 51 subjects randomized to CPAP, 25 (49%) experienced an improved outcome, as compared with 12 of 46 of subjects (26%) randomized to CT (p < 0.05). The odds of experiencing a treatment response in the CPAP as compared with the CT group were 2.72 (OR: 1.18 to 6.58, 95% CI). A beneficial effect of CPAP over CT was most evident among individuals without sinus problems and among subjects with hypertension or diabetes. Differential treatment responses were not related to degree of baseline sleepiness or SDB. This suggests that middle-aged snorers with relatively low levels of SDB (RDI < 30) may benefit more from nasal CPAP than from less specific therapy directed at improving breathing during sleep. CPAP therapy may be beneficial to a broader group of subjects than previously appreciated.

Decreased trkA neurotrophin receptor expression in the parietal cortex of patients with Alzheimer's disease

The cholinergic neurons of the basal forebrain system are sensitive to nerve growth factor (NGF), a member of the neurotrophin gene family. Since the cholinergic system is affected early in the course of Alzheimer's disease (AD), it was hypothesized that a deficit in NGF, e.g. reduced neurotrophin uptake by specific receptors, may play a role in neuronal cell death in AD. We quantitated mRNA levels of neurotrophins (NGF, BDNF, NT-3, NT-4/5) and their receptors (trkA, trkB, trkC, p75) in AD postmortem parietal cortex (n = 16) and cerebellum (n = 11). We applied highly sensitive reverse transcription-polymerase chain reaction (RT-PCR) in rapid autopsy derived brain tissue (mean postmortem delay 147+/-96 min., n = 53) to minimize postmortem mRNA variations. In the AD parietal cortex trkA mRNA levels were more than two times lower as compared to controls (n = 16, mean+/-SEM 0.26+/-0.07 units/S12, range, 0-1.78, and n = 11, 0.59+/-0.10 units/S12, range, 0.17-1.10, respectively, P = 0.015). TrkA mRNA levels did not appear to be altered in the AD cerebellum as compared to normal human cerebellum. NGF, BDNF, NT-3, NT-4/5, as well as trkB, trkC and p75 mRNA levels were unchanged in AD parietal cortex and cerebellum as compared to controls. This finding suggests that a reduced expression of the trkA receptor may contribute to impaired NGF-trkA signalling and a reduced transport of NGF in cholinergic neurons. These results reveal a central specific role of the high affinity NGF receptor during neurodegeneration in AD.

Relationship between "proto-splice sites" and intron phases: evidence from dicodon analysis

The coding sequence at the boundaries of exons flanking nuclear introns shows some degree of conservation. To the extent that such sequences might be recognized by the splicing machinery, this conservation may be a derived result of evolution for efficient splicing. Alternatively, such conserved sequences might be remnants of proto-splice sites, which might have existed early in eukaryotic genes and served as the targets for the insertion of introns, as has been proposed by the introns-late theory. The distribution of intron phases, the position of the intron within a codon, is biased with an over-representation of phase 0 introns. Could any distribution of proto-splice sites account for today's intron phase distribution? Here, we examine the dicodon usage in six model organisms, based on current sequences in the GenBank database, and predict the phase distribution that would be expected if introns had been inserted into proto-splice sites. However, these predictions differ between the various model organisms and disagree with the observed intron phase distributions. Thus, we reject the hypothesis that introns are inserted into hypothetical proto-splice sites. Finally, we analyze the sequences around the splice sites of introns in all six of the species to show that the actual conservation of sequence in exon regions near introns is very small and differs considerably between these species, which is inconsistent with a general proto-splice sites model.

RB1 deletion in gonadoblastoma in an XY female

Cytogenetic studies of normal and tumor cells in a patient with gonadal dysgenesis and bilateral gonadoblastoma were performed. The karyotype was 46,XY in peripheral blood lymphocytes and skin fibroblasts. The conserved region of the SRY gene was detected by polymerase chain reaction amplification. Sequencing of this region did not reveal any alterations. A 46,XY chromosome constitution was observed in the right gonadoblastoma, but a partial deletion of chromosome 13 was present in the left tumor. This deletion included band 13q14, where the retinoblastoma gene is mapped. The study of the polymorphism of the variable number of tandem repeats region in intron 17 of the RB1 locus disclosed loss of heterozygosity in both the left tumor, which showed the deletion of chromosome 13, and in the right tumor, where no chromosome alterations of chromosome 13 were detected. In situ hybridization covering 130 kb of RB1 showed that a partial deletion of one of the RB1 alleles had occurred in the right tumor. Since the deletions affected different alleles in each tumor, independent events must have been involved in the development of the tumors. These findings point toward a significant role of RB1 in the development of gonadoblastoma.

Interphase cytogenetics of prostatic tumor progression: specific chromosomal abnormalities are involved in metastasis to the bone

Only limited data are available on chromosomes specifically involved in the multistep tumorigenesis of prostate cancer. To investigate the cytogenetic status at different stages of prostatic tumor development, we have applied interphase in situ hybridization (ISH) with a set of (peri) centromeric DNA probes--specific for chromosomes 1, 7, 8, and Y--to routinely processed tissue sections of prostatic specimens from 75 different individuals. Our panel consisted of: 16 normal/benign prostatic hyperplasia specimens; 23 primary, localized, prostatic tumors (N0M0 stage); 20 regional lymph node metastases (M0 stage); and 16 distant metastases. Numerical aberrations of at least one chromosome were not observed in normal/benign prostatic hyperplasia cases, but were present in localized tumors (39%), regional lymph node metastases (40%), and distant metastases (69%). Within the different pTNM groups, we observed the following aberrations (listed, within each series, in decreasing order of frequency): -Y, +8, -8, +7 in primary tumors; +8, +7, -Y, +Y, -8 in regional lymph node metastases; and +8, +7, +1, -Y, -8 in distant metastases. In primary tumors, the number of aberrant cases increased significantly with local tumor stage (p < 0.05). A significant increase in gain of chromosome 8 was also observed (p < 0.02). Gain of chromosome 7 and/or 8 showed a significant increase with progression of local tumor stage (p < 0.02). Specific involvement of chromosome 8 was seen in bone metastases, but not in hematogenous metastases to other sites (p = 0.02). Comparative genomic hybridization analysis of these bone metastases disclosed centromere 8 gains as amplifications of the (whole) 8q arm, whereas centromeric loss appeared to be due to loss of 8p sequences. With progression toward metastatic disease, an accumulation of genetic changes was seen as exemplified by gain of chromosome 1, which was solely observed in distant metastases. With tumor progression, gain of chromosomes 7 and/or 8 significantly increased (p = 0.03), whereas the number of cases with aberrations of the Y chromosome did not change. Furthermore, ploidy status determined by ISH revealed a significant increase in the number of aneuploid cases along with advancement of pTNM stage (p = 0.04). Collectively, the data strongly suggest that: (a) gain of chromosome 7 and/or 8 sequences is implicated in prostatic tumor progression; (b) gain of chromosome 8 sequences is related to local tumor growth; (c) overrepresentation of 8q sequences, most likely by isochromosome 8q formation, is involved in metastatic spread to the bone; and (d) changes in the centromeric copy number, as detected by interphase ISH, might in some cases represent structural alterations, such as an isochromosome.

Comparative genomic hybridization in hypotriploid/hyperdiploid tumors

Hypotriploidy/hyperdiploidy ("intermediate ploidy") often occurs in testicular germ cell tumors of adolescents and adults. Disomic and trisomic chromosomes represent significant parts of the tumor genome and a few chromosomes fall outside the two- to three-copy number range. We performed comparative genomic hybridization (CGH) with DNA isolated from a cell line from a case of testicular germ cell tumor of adolescents and adults and found most of the ratio values to be dislocated from the baseline 1.0 and placed adjacent of the diagnostic thresholds of 0.8 and 1.2. We attributed that to the fact that, in current software packages for analysis of CGH, the fluorescence ratio baseline is assumed to correspond to the copy number of most loci of the genome. We then evaluated, instead of the commonly used fluorescent ratio value from the whole metaphase, the use of the fluorescence ratios of single chromosomes. The results permitted a clear distinction between the chromosomes with two and three copies and, in particular, of the regions deleted or amplified outside the two- to three-copy range. We concluded that the evaluation of unbalances of DNA copy number in intermediate ploidy cases is best carried out using multiple normalization.

Interphase cytogenetics and comparative genomic hybridization of human epithelial cancers and precursor lesions

The accuracy of cytogenetic analyses of human solid cancers has improved enormously over the past decade by the introduction and refinement of DNA in situ hybridization (ISH) techniques. This methodology can be applied to cells in the interphase state, thereby making it an excellent tool for the delineation of chromosomal aberrations in solid tumors. The use of non-isotopic ISH to intact and disaggregated cancer specimens will be discussed, as well as comparative genomic hybridization (CGH) with tumor-derived DNAs. In this review we will focus on hybridocytochemical interphase approaches for the detection of chromosomal changes in frequently occurring human epithelial malignancies, e.g., breast, lung, and prostate carcinomas. We will further discuss the use of ISH procedures for the genetic analysis of precursor conditions leading to invasive carcinomas. Knowledge concerning these precancerous conditions is increasing, and its importance in cancer prevention has been recognized. Interphase cytogenetics by ISH, as well as CGH, with DNAs derived from microdissected, precancerous, dysplastic tissue areas will increase our understanding of these lesions, both at the investigative and diagnostic levels.

Skin cancer prevention education: a national survey of YMCAs

High skin cancer incidence and mortality rates have created a need for skin cancer prevention education. Children are an important target for this education, as overexposure to sun and sunburns at an early age have been linked to the development of skin cancer. This study identified the prevalence of skin cancer prevention education and the need for this education at YMCA swim classes. This study also assessed the feasibility of implementing Project SUNWISE, an existing skin cancer prevention curriculum, developed for YMCA swim classes. A 51-item survey was mailed to Aquatics Directors at all YMCAs with outdoor pools. Based on a 63% response rate (N = 208), only 28% of YMCAs thought the children in their swim classes were adequately protected from the sun, and only 28% offered skin protection or sun safety education in swim classes. Only 50% of YMCAs trained their swim instructors on skin cancer prevention. While 91% of YMCAs had one or more sun protection items near the pool (e.g., sunscreen, umbrella, covered area), 93% of YMCAs saw the need for additional protection. The majority of YMCAs (95%) were willing to incorporate a skin cancer prevention education curriculum, similar to Project SUNWISE, into their swim classes. This study emphasized the need for more skin cancer prevention education programs targeting children and examined the correlates of skin cancer prevention education at YMCAs. Geographic region, percent of possible sunshine, and ultraviolet radiation were significantly associated with the skin cancer prevention education program status at the YMCAs.

Reducing ultraviolet radiation exposure in children

BACKGROUND

Project SUNWISE evaluated the effectiveness of a multicomponent intervention in reducing children's ultraviolet radiation (UVR) exposure.

METHODS

Across four YMCAs, 48 aquatics classes (N = 169 children, mean age = 7) were randomly assigned to either the intervention or the control condition. The 6-week intervention included a UVR reduction curriculum presented at poolside by aquatics instructors and home-based activities for children and their parents. Outcome measures were (a) tanness-associated skin color dimensions assessed with a colorimeter, (b) specific daily solar protection behaviors of children as reported by parents, and (c) general solar protection behaviors.

RESULTS

Controlling for intraclass clustering in all analyses, at posttest, no statistically significant between-group differences were found in tanness, daily solar protection scores, or general sunscreen use. The intervention group showed significantly greater general hat use relative to controls.

CONCLUSIONS

The intervention failed to impact most of the outcome measures. Supplementing the behavior-focused intervention package with environmental supports may be warranted.

Characteristic pattern of chromosomal gains and losses in marginal zone B cell lymphoma detected by comparative genomic hybridization

Marginal zone B cell lymphoma (MZBCL) represents a distinct subtype of B cell non-Hodgkin's lymphoma, which has been recently recognized and defined as a disease entity. We investigated 25 cases (18 at primary diagnosis and seven during the course of disease) of MZBCL by comparative genomic hybridization (CGH) and compared these results with cytogenetic, fluorescence in situ hybridization (FISH), and Southern blot data. Twenty of the 25 cases (80%) showed gains (total 49) or losses (total 15) of genetic material. In extranodal, nodal, and splenic MZBCL, material of chromosomes 3 (52% of cases), 18 (32%), X (24%), and 1q (16%) was most frequently gained, whereas losses predominantly involved chromosomes 17 (16%) and 9 (12%). High-level amplifications involving the regions 18q21-23 and 18q21-22, respectively, were detected in two cases. Gains of chromosomes 1q and 8q and losses of chromosome 17 or 17p occurred more frequently in relapsed or progressive lymphomas. For all of the frequently affected chromosomes, CGH allowed narrowing of the relevant subregions including 3q21-23, 3q25-29 and 18q21-23. By Southern blot analysis, the BCL2, BCL6, and CMYC proto-oncogenes were found to be a part of the over-represented regions in two cases, one case, and two cases, respectively, with gains involving 18q, 3q or 8q. In 13 cases, CGH revealed chromosomal imbalances which were not detected by cytogenetic analysis but could be confirmed by FISH or Southern blot analysis in all cases investigated. On the other hand, CGH failed to detect trisomy 3, trisomy 18, and deletion 7q in three cases with a low proportion of tumor cells bearing these abnormalities, as shown by interphase FISH. The characteristic pattern of chromosomal gains and losses detected in this study confirms the distinct nature of MZBCL and may point to chromosomal regions involved in the pathogenesis of these neoplasms.

Cytogenetic effects of softwood kraft pulp bleaching effluents and methanesulfonyl chloride in Chinese hamster ovary cells

The genotoxicity of effluents collected from a conventional 5-stage softwood kraft pulp bleaching process was studied in Chinese hamster ovary (CHO) cells in vitro. Spent liquor from the first chlorination stage (C/D), where elemental chlorine and chlorine dioxide had been used in equal proportions, was shown to induce a dose-dependent increase in sister chromatid exchanges (SCEs) without metabolic activation (4-h treatment), with a maximum increase of 1.6 times over the control level at 204 microliters/ml; this dose also induced 15.5- and 20.5-fold increases in cells with chromatid-type chromosomal aberrations after 4-h and a 20-h treatment, respectively. Another C/D stage spent liquor from a process where the ratio of elemental chlorine and chlorine dioxide had been 9:1 produced a 40.5-fold elevation of cells with chromatid-type aberrations at 204 microliters/ml (20-h treatment). This sample clearly increased chromosomal aberrations also when tested as a concentrate (4-h treatment), which showed that the observed clastogenicity was not unspecifically due to the relatively large volumes used in the treatments with the unconcentrated liquors. In general, the use of rat liver S9 mix reduced the genotoxicity of the spent liquors. The results agree with earlier findings on the Salmonella mutagenicity of the same C/D samples: both the prokaryotic and eukaryotic assays showed a reduction in genotoxicity when the amount of elemental chlorine in the bleaching process was reduced. An effluent sample collected from the alkaline stage of the process was not clastogenic with or without metabolic activation. Methanesulfonyl chloride, a new compound identified in bleaching plant air, was found to be induce chromosomal aberrations in the presence of S9 mix.

Neuropsychological function in mild sleep-disordered breathing

Although a broad range of neuropsychological deficits has been reported in patients with severe sleep disordered breathing (SDB), little is known about the impact of mild SDB on neuropsychological performance. In this study, we compared neuropsychological test performance in two groups of carefully screened volunteers who differed clearly according to the respiratory disturbance index (RDI). Controls (n = 20) were identified on the basis of an RDI < 5; cases (n = 32) had an RDI in the range of 10-30. Cases and controls were well matched with regard to IQ, age, and sex. Cases had significantly more self-reported snorting and apneas and a higher body mass index than controls but did not differ according to sleepiness as measured by either the multiple sleep latency test or the Epworth sleepiness scale. An extensive battery of neuropsychological and performance tests was administered after an overnight sleep study. Cases performed significantly more poorly on a visual vigilance task (perceptual sensitivity, d': 2.24 +/- 0.64 vs. 2.70 +/- 0.53, p = 0.01, for cases and controls, respectively) and a test of working memory, the Wechsler adult intelligence scale-revised digits backwards test (6.12 +/- 2.20 vs. 7.55 +/- 2.22, p = 0.02), than controls. The groups did not differ in their performance on other tests of memory, information processing, and executive functioning. In summary, subjects with mild SDB may manifest a vigilance deficit in the absence of substantial sleepiness. Subjects with a mildly elevated RDI (10-30) without sleepiness do not appear to suffer appreciable deficits in more complex neuropsychological processes (e.g. executive functions).

Effects of menopause and nasal occlusion on breathing during sleep

Prevalence of sleep-disordered breathing (SDB) is reported to increase in menopausal women. We examined response to a nocturnal respiratory challenge (nasal occlusion) during overnight polysomnography in 31 women (45 to 55 yr). Thirteen were premenopausal, four perimenopausal, and 14 postmenopausal by history and hormonal assay. Nasal occlusion increased the apnea hypopnea index (AHI) (occlusion mean = 6.6 +/- 8.0 versus baseline mean = 1.6 +/- 2.6, p < 0.01) and arousal index (occlusion mean = 35.1 +/- 20.1 versus baseline mean = 20.7 +/- 11.6, p < 0.001), but did not change the oxygen saturation nadir in those with respiratory events (occlusion mean = 91.8 +/- 4.2 versus baseline mean = 92.0 +/- 11.6). Menopausal groups did not differ on AHI, arousal index, or oxygen saturation nadir in either condition. Key variables were compared between occlusion responders (n = 11) and nonresponders (n = 20). Responders and nonresponders were not distinguished by age, menopausal status, nor several cephalometric or anthropometric variables. Body mass index (31.1 +/- 8.5 versus 24.3 +/- 3.4, p < 0.003), neck circumference (34.0 +/- 2.5 versus 32.5 +/- 1.7 cm, p < 0.05), and mandibular-hyoid distance (18.5 +/- 3.8 versus 14.5 +/- 5.7 mm, p < 0.05) were greater in responders. These findings suggest hormonal factors may be less important than weight and facial morphology in midlife development of SDB in women.

The NodA proteins of Rhizobium meliloti and Rhizobium tropici specify the N-acylation of Nod factors by different fatty acids

Rhizobia synthesize mono-N-acylated chitooligosaccharide signals, called Nod factors, that are required for the specific infection and nodulation of their legume hosts. The biosynthesis of Nod factors is under the control of nodulation (nod) genes, including the nodABC genes present in all rhizobial species. The N-acyl substitution can vary between species and can play a role in host specificity. In Rhizobium meliloti, an alfalfa symbiont, the acyl chain is a C16 unsaturated or a (omega-1) hydroxylated fatty acid, whereas in Rhizobium tropici, a bean symbiont, it is vaccenic acid (C18:1). We constructed R. meliloti derivatives having a non-polar deletion of nodA, and carrying a plasmid with either the R. meliloti or the R. tropici nodA gene. The strain with the R. tropici nodA gene produced Nod factors acylated by vaccenic acid, instead of the C16 unsaturated or hydroxylated fatty acids characteristic of R. meliloti Nod factors, and infected and nodulated alfalfa with a significant delay. These results show that NodA proteins of R. meliloti and R. tropici specify the N-acylation of Nod factors by different fatty acids, and that allelic variation of the common nodA gene can contribute to the determination of host range.

Relationship between sleepiness and general health status

One commonly used instrument for evaluating general health and functional status is the medical outcomes survey short form 36 (MOS). Scores obtained from this instrument are known to vary with chronic diseases and depression. However, the degree to which these health dimensions may be influenced by sleep quality or sleepiness is not well understood. A cross-sectional study was performed on the association between general health status, as determined by the MOS, with sleepiness, assessed using a standardized questionnaire [the Epworth sleepiness scale (ESS)] and the multiple sleep latency test (MSLT). One hundred twenty-nine subjects (68 women), aged 25-65 years, without severe chronic medical or psychiatric illnesses, underwent an overnight sleep study, followed by an MSLT (consisting of a series of four attempts at napping at 2-hour intervals), and completed the MOS and the ESS. The mean MSLT score was 11 +/- 2 minutes, (range 2-20) and the mean ESS score was 10 +/- 5 (range 0-24). Scores for the MOS dimensions "general health perceptions", "energy/fatigue", and "role limitations due to emotional problems" were correlated significantly with ESS scores (r = -0.30, -0.41, and -0.30, respectively; p values were all < 0.001). The MSLT was also significantly correlated with "energy/fatigue" (r = -0.19; p < 0.05). After considering the effects of chronic illness and/or body mass index in a multiple hierarchical regression analysis, sleepiness, as assessed by the ESS score, explained 8% of the variance in general health perceptions, 17% of the variance in energy/fatigue, 6% of the variance in the summary measure of well-being, and 3% of the variance in the summary measure of functional status. The variation of MOS scores with sleepiness, unrelated to age or chronic disease, suggests that measures of general health status may be broadly influenced by sleepiness and sleep quality. These data suggest that 1) sleepiness has an important impact on general health and functional status, specifically influencing self-perceptions regarding energy/fatigue; 2) a more specific assessment of sleepiness in general health evaluations may help explain some of the observed variability in these measures across subjects; and 3) general health measures may be useful in the evaluations of patients with sleep disorders.

Exon shuffling and the origin of the mitochondrial targeting function in plant cytochrome c1 precursor

Since most of the examples of "exon shuffling" are between vertebrate genes, the view is often expressed that exon shuffling is limited to the evolutionarily recent lineage of vertebrates. Although exon shuffling in plants has been inferred from the analysis of intron phases of plant genes [Long, M., Rosenberg, C. & Gilbert, W. (1995) Proc. Natl. Acad. Sci. USA 92, 12495-12499] and from the comparison of two functionally unknown sunflower genes [Domon, C. & Steinmetz, A. (1994) Mol. Gen. Genet. 244, 312-317], clear cases of exon shuffling in plant genes remain to be uncovered. Here, we report an example of exon shuffling in two important nucleus-encoded plant genes: cytosolic glyceraldehyde-3-phosphate dehydrogenase (cytosolic GAPDH or GapC) and cytochrome c1 precursor. The intron-exon structures of the shuffled region indicate that the shuffling event took place at the DNA sequence level. In this case, we can establish a donor-recipient relationship for the exon shuffling. Three amino terminal exons of GapC have been donated to cytochrome c1, where, in a new protein environment, they serve as a source of the mitochondrial targeting function. This finding throws light upon an old important but unsolved question in gene evolution: the origin of presequences or transit peptides that generally exist in nucleus-encoded organelle genes.