Systematic interindividual differences in neurobehavioral impairment from sleep loss: evidence of trait-like differential vulnerability

OBJECTIVES: To investigate interindividual differences in neurobehavioral deficits during sleep deprivation, and to establish to what extent the neurobehavioral responses to sleep loss are a function of sleep history versus trait-like differential vulnerability. DESIGN: Individuals were exposed to sleep deprivation on 3 separate occasions in order to determine the stability of interindividual differences in neurobehavioral impairment. SETTING: The sleep-deprivation experiments were conducted under standardized laboratory conditions with continuous monitoring of wakefulness. Each subject underwent a laboratory-adaptation session before entering the sleep-deprivation phase of the study. PARTICIPANTS: A total of 21 healthy adults (aged 21-38 years) completed the experiment. INTERVENTIONS: Subjects came to the laboratory 3 times at intervals of at least 2 weeks. During each laboratory session, they underwent neurobehavioral testing every 2 hours during 36 hours of total sleep deprivation, which was preceded by baseline sleep and followed by recovery sleep. In the week prior to each sleep-deprivation session and on the baseline night in the laboratory, subjects were required to either restrict their sleep to 6 hours per day (prior sleep restriction condition) or to extend their time in bed to 12 hours per day (prior sleep extension condition), so as to experimentally manipulate sleep history (in randomized counterbalanced order). RESULTS: There was strong evidence that interindividual differences in neurobehavioral deficits during sleep deprivation were systematic and trait-like. The magnitude of interindividual variability was substantial relative to the magnitude of the effect of prior sleep restriction (which on average involved a reduction of 4.1 hours sleep per day, compared to prior sleep extension, for 7 days). Overall, interindividual differences were not explained by subjects' baseline functioning or a variety of other potential predictors. Interindividual variability clustered on 3 distinct neurobehavioral dimensions: self-evaluation of sleepiness, fatigue, and mood; cognitive processing capability; and behavioral alertness as measured by sustained attention performance. CONCLUSIONS: Neurobehavioral deficits from sleep loss varied significantly among individuals and were stable within individuals. Interindividual differences in neurobehavioral responses to sleep deprivation were not merely a consequence of variations in sleep history. Rather, they involved trait-like differential vulnerability to impairment from sleep loss, for which neurobiologic correlates have yet to be discovered.     

HLA alleles and haplotypes among the Lakota Sioux: report of the ASHI minority workshops, part III

Human leukocyte antigen (HLA) class I and II alleles were defined for 302 Lakota Sioux American Indians as part of the American Society for Histocompatibility and Immunogenetics coordinated studies on minority populations. The study group was comprised of adult volunteers from the Cheyenne River and Ogala Sioux tribes residing, respectively, on the Cheyenne River and Pine Ridge Reservations in South Dakota. Of the participants, 263 (87%) claimed full American Indian ancestry through both maternal and paternal grandparents. The study group included 25 nuclear families that were informative for genotyping. HLA phenotypes from 202 adults with no other known first-degree relative included in the study were used for calculation of allele and haplotype frequencies by maximum likelihood estimation. HLA-A, -B, and -Cw alleles were found to be in Hardy Weinberg equilibrium. Deviation from equilibrium was observed for DRB1 alleles (p=0.01), but could be attributed to the sample size and the occurrence of some genotypes with low expected frequencies. Polymorphism among the Sioux was limited with four to seven alleles comprising >80% of those observed at each locus. Several alleles were found at high frequency (0.05-0.30) among the Sioux that are also prevalent in other Native Americans and Alaska Natives, including: A*2402, *3101, and *0206; B*3501,*3901, *5101, and *2705; Cw*0702, *0404, and *03041; DRB1*0407, *0404, *1402, and *16021; and DQB1*0301, *0302, and *0402. DRB1*0811, which has been only previously described in Navajo and Tlingit Indians, was found to occur at a frequency of 0.119 among the Sioux. Two new alleles were defined among the Sioux: Cw*0204 and DRB1*040703, which were found in two and four individuals, respectively. In the haplotype analyses, significant linkage disequilibrium (p<0.00001) was seen in all pairwise comparisons of loci and numerous two and three locus haplotypes were found to have strong, positive linkage disequilibrium values. The two most common extended haplotypes among the Sioux, determined by maximum likelihood estimation and genotyping were: A*31012, B*3501, Cw*0404, DRB1*0407; and A*24021, B*3501, Cw*0404, DRB1*0404.     

An orthotopic metastatic prostate cancer model in SCID mice via grafting of a transplantable human prostate tumor line

Metastasis is the major cause of prostate cancer deaths and there is a need for clinically relevant in vivo models allowing elucidation of molecular and cellular mechanisms underlying metastatic behavior. Here we describe the development of a new in vivo model system for metastatic prostate cancer. Pieces of prostate cancer tissue from a patient were grafted in testosterone-supplemented male NOD-SCID mice at the subrenal capsule graft site permitting high tumor take rates. After five serial transplantations, the tumor tissues were grafted into mouse prostates. Resulting tumors and suspected metastatic lesions were subjected to histopathological and immunohistochemical analysis. Samples of metastatic tissue were regrafted in mouse anterior prostates and their growth and spread examined, leading to isolation from lymph nodes of a metastatic subline, PCa1-met. Orthotopic grafting of PCa1-met tissue in 47 hosts led in all cases to metastases to multiple organs (lymph nodes, lung, liver, kidney, spleen and, notably, bone). Histopathological analysis showed strong similarity between orthotopic grafts and their metastases. The latter were of human origin as indicated by immunostaining using antibodies against human mitochondria, androgen receptor, prostate-specific antigen and Ki-67. Spectral karyotyping showed few chromosomal alterations in the PCa1-met subline. This study indicates that transplantable subrenal capsule xenografts of human prostate cancer tissue in NOD-SCID mice can, as distinct from primary cancer tissue, be successfully grown in the orthotopic site. Orthotopic xenografts of the transplantable tumor lines and metastatic sublines can be used for studying various aspects of metastatic prostate cancer, including metastasis to bone.     

Associations between total serum IgE levels and the 6 potentially functional variants within the genes IL4, IL13, and IL4RA in German children: the German Multicenter Atopy Study

BACKGROUND: Increased total serum IgE levels are a common characteristic of atopic disorders. Six potentially functional variants, including C-590T in the IL4 gene, C-1055T and Arg130Gln in the IL13 gene, and Ile50Val, Ser478Pro, and Gln551Arg in the IL4RA gene, have been evaluated for their involvement in the control of total serum IgE levels and related atopic disorders, but the results of these studies have been inconsistent. OBJECTIVE: We examined whether these 6 variants had genotypic effects on total serum IgE levels in 823 unrelated German children from a large infant cohort, the German Multicenter Atopy Study. METHODS: Marginal effect models were used for the analyses of the repeated IgE measurements. Weighted linear regression and family-based tests of association were performed to minimize the possibility of spurious effects caused by selection bias or confounding on the basis of ethnic background. RESULTS: There are significant associations between increased total serum IgE levels and 2 variants in the IL13 gene (P <.005 and.0002 for Arg130Gln and C-1055T, respectively). These genetic effects are unlikely to be due to solely linkage disequilibrium between 2 polymorphisms, population stratification, or nonrepresentative samples. In addition, exposure to maternal smoking appears to modify the above effects on total serum IgE levels. However, no statistical association was observed between this quantitative phenotype and the other 4 variants examined. CONCLUSION: These findings suggest that variants C-1055T and Arg130Gln of the IL13 gene might play an important role on total serum IgE production in this study population.     

Autoantibodies to heat shock protein 90 in the human natural antibody repertoire

The present study demonstrates the presence of natural autoantibodies of the IgG isotype directed against heat shock protein 90 (HSP90). The binding properties of affinity-purified anti-HSP antibodies were compared with those of natural antibodies specific for other self antigens, including anti-thyroglobulin and anti-myoglobin autoantibodies, by using semiquantitative immunoblotting, with solubilized proteins from normal liver tissue as antigens, and cross-blot analysis using purified self proteins. Affinity-purified anti-HSP90 antibodies were polyreactive and the non-HSP90-specific fraction of normal IgG was depleted in its natural autoantibody content. We further observed that self antigens including HSP, myosin, tubulin and aldolase with highly conserved structures show similar patterns of binding with natural antibodies, and form a well-defined cluster as demonstrated by cluster analysis of immunoreactivity data, whereas the less-conserved self and non-self antigens remained unclustered. The results favor the hypothesis that HSP90 belongs to a subset of highly conserved and immunodominant self antigens that are the primary target for natural autoantibodies in normal human IgG.     

Infantile hypotonia as a presentation of Rett syndrome

Rett syndrome (RTT) is classically defined by meeting certain clinical diagnostic criteria. It affects mostly females, and one possible pathogenic mechanism was considered to involve mitochondrial function. This was based on the finding of ultrastructural alterations in the mitochondria and decreased respiratory chain enzyme activity. However, the principal etiology of RTT has since been found to be mutations in the MECP2 gene, which is located on the X chromosome. Molecular analysis has allowed the phenotype of MECP2 mutations to be broadened beyond RTT to include girls who have mild mental retardation, autism, and an Angelman syndrome phenotype, as well as males with severe encephalopathy. We present a girl with a previously described mutation in the MECP2 gene whose phenotype is of atypical RTT. She presented with hypotonia and developmental delay in infancy without a clear period of normal development. As part of her evaluation for hypotonia, a muscle biopsy and respiratory chain enzyme analysis showed a slight decrease in respiratory chain enzyme activity consistent with previous reports. This report supports broadening the phenotype of patients who should be considered for MECP2 mutation analysis to include cases of developmental delay and hypotonia without evidence of an initial period of normal development. Furthermore, it supports the hypothesis of an underlying secondary defect in energy metabolism contributing to the pathogenesis of RTT.     

PCR analysis of egyptian respiratory adenovirus isolates, including identification of species, serotypes, and coinfections

Eighty-eight adenovirus (Ad) isolates and associated clinical data were collected from walk-in patients with influenza-like illness in Egypt during routine influenza surveillance from 1999 through 2002. Respiratory Ad distributions are geographically variable, and serotype prevalence has not been previously characterized in this region. Serotype identity is clinically relevant because it predicts vaccine efficacy and correlates strongly with both clinical presentation and epidemiological pattern. Species and serotype identities were determined using several well-validated multiplex PCR protocols culled from the literature and supplemented with a few novel primer sets designed to identify rare types. The isolates included common species B1 serotypes (Ad3 and Ad7), common species C serotypes (Ad1, Ad2, and Ad5), the less common species B2 serotype Ad11, and three isolates of the rare species B1 serotype Ad16. Two isolates that appear to be variant Ad16 were also identified. Fifteen coinfections of multiple adenoviral types, primarily AdB/AdC and Ad3/Ad7 dual infections, were detected. The majority of these were verified using redundant PCR tests targeted at multiple genes. PCR is able to resolve coinfections, in contrast to traditional serum neutralization tests. PCR is also comparatively rapid and requires very little equipment. Application of the method allowed an inclusive determination of the serotypes found in the Egyptian respiratory sample set and demonstrated that coinfections are common and may play a previously unrecognized role in adenovirus pathogenesis, evolution, and epidemiology. In particular, coinfections may influence adenoviral evolution, as interserotypic recombination has been identified as a source of emerging strains.     

Parallel genotyping of over 10,000 SNPs using a one-primer assay on a high-density oligonucleotide array

The analysis of single nucleotide polymorphisms (SNPs) is increasingly utilized to investigate the genetic causes of complex human diseases. Here we present a high-throughput genotyping platform that uses a one-primer assay to genotype over 10,000 SNPs per individual on a single oligonucleotide array. This approach uses restriction digestion to fractionate the genome, followed by amplification of a specific fractionated subset of the genome. The resulting reduction in genome complexity enables allele-specific hybridization to the array. The selection of SNPs was primarily determined by computer-predicted lengths of restriction fragments containing the SNPs, and was further driven by strict empirical measurements of accuracy, reproducibility, and average call rate, which we estimate to be >99.5%, >99.9%, and>95%, respectively [corrected]. With average heterozygosity of 0.38 and genome scan resolution of 0.31 cM, the SNP array is a viable alternative to panels of microsatellites (STRs). As a demonstration of the utility of the genotyping platform in whole-genome scans, we have replicated and refined a linkage region on chromosome 2p for chronic mucocutaneous candidiasis and thyroid disease, previously identified using a panel of microsatellite (STR) markers.     

In vitro degradation of polymeric networks of poly(propylene fumarate) and the crosslinking macromer poly(propylene fumarate)-diacrylate

Polymeric networks of poly(propylene fumarate) (PPF) crosslinked with poly(propylene fumarate)-diacrylate (PPF-DA) are currently being investigated as an injectable, biodegradable bone cement. This study examined the effect of crosslinking density, medium pH, and the incorporation of a beta-tricalcium phosphate (beta-TCP) filler on the in vitro degradation of PPF/PPF-DA. Cylindrical specimens were submerged in buffered saline at 37 degrees C and the change in weight, geometry, and compressive mechanical properties were monitored over a 52-week period. All formulations showed an initial increase in modulus and yield strength over the first 12 weeks, achieving maxima of 1307+/-101 and 51+/-3MPa, respectively, for the beta-TCP composite. PPF/PPF-DA networks with the lower crosslinking density demonstrated the greatest degradation with a 17% mass loss. Samples in the lower buffer pH 5.0 compared to physiological pH 7.4 did not show any differences in mass loss, but exhibited a faster decrease in the compressive strength over time. The beta-TCP composites maintained their mechanical properties at the level following their initial increase. These results show that the degradation of PPF/PPF-DA networks can be controlled by the crosslinking density, accelerated at a lower pH, and prolonged with the incorporation of the beta-TCP filler.     

Lactoferrin and eosinophilic cationic protein in nasal secretions of patients with experimental rhinovirus colds, natural colds, and presumed acute community-acquired bacterial sinusitis

To distinguish sinusitis from uncomplicated "colds," we examined lactoferrin and eosinophilic cationic protein (ECP) in nasal secretions. Lactoferrin titers were >/=1:400 in 4% of persons with uncomplicated colds and controls but in 79% of persons with sinusitis or purulent sputa. ECP levels were >200 ng/ml in 61% of persons with colds and >3,000 ng/ml in 62% of persons with sinusitis. Nasal lactoferrin helps distinguish sinusitis from colds.