Deleterious effects of an environmental noise on sleep and contribution of its physical components in a rat model

Sleep disturbances induced by environmental noise (EN) exposure are now well admitted. However, many contradictory conclusions and discrepancies have been reported, resulting from uncontrolled human factors or the use of artificial noises (pure tone). Thus, the development of an animal model appears to be a useful strategy for determining whether EN is deleterious to sleep. The aims of this study were: (i) to confirm the effects of noise on sleep in a rat model; and (ii) to determine the most deleterious physical component of noise regarding sleep structure. For this purpose, rats were exposed during 24 h either to EN or to artificial broad-band noises [either continuous broad-band noise (CBBN) or intermittent broad-band noise (IBBN)]. All the noises decrease both slow wave sleep (SWS) and paradoxical sleep (PS) amounts during the first hours of exposure. However, CBBN acts indirectly on PS through a reduction of SWS bout duration, whereas IBBN and EN disturb directly and more strongly both SWS and PS. Finally, EN fragments SWS and decreases PS amount during the dark period, whereas IBBN only fragments PS. These results demonstrate the validity and suitability of a rodent model for studying the effects of noise on sleep and definitively show that sleep is disturbed by EN exposure. Two physical factors seem to be implicated: the intermittency and the frequency spectrum of the noise events, which both induce long-lasting sleep disturbances. An additive effect of frequency spectrum to intermittency tends to abolish all possible adaptations to EN exposure. Since sleep is involved in cognitive processes, such disturbances could lead to cognitive deficits.     

Doctorial dissertations on nurse practitioners: 1970-2000

PURPOSE: To understand more about the nurse practitioner (NP) profession, a study was undertaken of the dissertation literature. DATA SOURCES: A search of Dissertation Abstracts Online yielded 134 dissertations that included NPs in the title or abstract and were awarded between 1970 and 2000. CONCLUSIONS: Most of the degrees are either PhD (61%) or EdD (27%). State-based universities produced the most degrees (70%) and six universities accounted for one-fourth of the degrees. The topics of NP-focused dissertations are wide ranging and include history, medical economics and managed care, NP education and professional role, and clinical and behavioral research. IMPLICATIONS FOR PRACTICE: This dataset provides an important source of information for research on the NP profession.     

Genome linkage screen for prostate cancer susceptibility loci: results from the Mayo Clinic Familial Prostate Cancer Study

Prostate cancer is one of the most common cancers among men and has long been recognized to occur in familial clusters. Brothers and sons of affected men have a twofold to threefold increased risk of developing prostate cancer. However, identification of genetic susceptibility loci for prostate cancer has been extremely difficult. Several putative loci identified by genetic linkage have been reported to exist on chromosomes 1 (HPC1, PCAP, and CAPB), X (HPCX), 17 (HPC2), and 20 (HPC20), with genes RNASEL (HPC1) and ELAC2 (HPC2) tentatively defined. In this study, we report our genome linkage scan in 160 prostate cancer families, using the ABI Prism Linkage Mapping Set Version 2 with 402 microsatellite markers. The most significant linkage was found for chromosome 20, with a recessive model heterogeneity LOD score (HLOD) of 4.77, and a model-free LOD score (LOD - ZLR) of 3.46 for the entire group of pedigrees. Linkage for chromosome 20 was most prominent among families with a late age of diagnosis (average age at diagnosis >/= 66 years; maximum LOD - ZLR = 2.82), with <5 affected family members (LOD - ZLR = 3.02), with presence of hereditary prostate cancer (LOD - ZLR = 2.81), or with no male-to-male transmission of disease (LOD - ZLR = 3.84). No other chromosome showed significant evidence for linkage. However, chromosomes 6 and X showed suggestive results, with maximum LOD - ZLR values of 1.38 and 1.36, respectively. Subset analyses suggest additional chromosomal regions worth further follow-up.