Universal DNA methylation age across mammalian tissues

Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals.

Presence of Antibodies Against Haemophilus influenzae Serotype a in Alaska Before and After the Emergence of Invasive Infections

BACKGROUND

Haemophilus influenzae bacteria can cause asymptomatic carriage and invasive disease. Haemophilus influenzae serotype a (Hia) is an emerging cause of invasive disease in Alaska, with greatest burden occurring among rural Alaska Native (AN) children. The first case of invasive Hia (iHia) in Alaska was reported in 2002; however, it is unclear how long the pathogen has been in Alaska.

METHODS

We quantified immunoglobulin G antibodies against Hia (anti-Hia) in 839 banked serum samples from Alaska residents, comparing antibody concentrations in samples drawn in the decades before (1980s and 1990s) and after (2000s) the emergence of iHia. We also assessed serum antibody concentration by age group, region of residence, and race.

RESULTS

The anti-Hia was >0.1 µg/mL in 88.1% (348 of 395) and 91.0% (404 of 444) of samples from the decades prior and after the emergence of Hia, respectively (P = .17). No significant differences in antibody levels were detected between people from rural and urban regions (1.55 vs 2.08 µg/mL, P = .91 for age ≥5) or between AN and non-AN people (2.50 vs 2.60 µg/mL, P = .26).

CONCLUSIONS

Our results are consistent with widespread Hia exposure in Alaska predating the first iHia case. No difference in Hia antibody prevalence was detected between populations with differing levels of invasive disease.

Ixodes scapularis (Acari: Ixodidae) Nymphal Survival and Host-Finding Success in the Eastern United States

The blacklegged tick (Ixodes scapularis Say) is the primary vector of Borrelia burgdorferi sensu stricto (Spirochaetales: Spirochaetaceae), the Lyme disease agent in North America. The basic reproduction number (R0) for B. burgdorferi in I. scapularis in the Northeast is highly sensitive to the probability that engorged larvae survive the winter, molt into nymphs, and find a host. These processes are dependent on local environmental variables, including climate, host population size and movement, and tick behavior. A simple model is presented for estimating host-finding success from the ratio of tick abundance in two subsequent years, accounting for overwinter survival and possible differences in host associations between nymphs and larvae. This model was parameterized using data from two sites in mainland Connecticut and two on Block Island, RI. Host abundance and tick burdens were estimated via mark-recapture trapping of the primary host, Peromyscus leucopus Rafinesque. Overwintering survival was estimated using engorged larvae placed in field enclosures at each site. Only nymphs were recovered alive, and no significant differences in model parameters were observed between Connecticut and Block Island. Host-finding success was predicted to be high across a wide range of host association patterns at three of four sites. Assuming equivalent host association between larvae and nymphs, R0 was also estimated to be greater than one at three of four sites, suggesting these conditions allow for the persistence of B. burgdorferi. The model output was highly sensitive to differences between nymphal and larval host associations.

Incorporating Health Outcomes into Land-Use Planning

The global trend toward increased agricultural production puts pressure on undeveloped areas, raising the question of how to optimally allocate land. Land-use change has recently been linked to a number of human health outcomes, but these are not routinely considered in land-use decision making. We review examples of planners' currently used strategies to evaluate land use and present a conceptual model of optimal land use that incorporates health outcomes. We then present a framework for evaluating the health outcomes of land-use scenarios that can be used by decision makers in an integrated approach to land-use planning.

Climate impacts on blacklegged tick host-seeking behavior

The nymph of the blacklegged tick (Ixodes scapularis), the primary North American vector of the causative agent of Lyme disease, must attach to a host by the end of its questing season in order to feed and subsequently molt into an adult. The proper timing of this behavior is critical both for the tick's survival and for perpetuating the transmission of tick-borne pathogens. Questing also depletes limited nymphal lipid reserves and increases desiccation risk. Given this tradeoff, questing behavior and its environmental influences can be expressed in a dynamic state variable model. We develop what we believe to be the first such model for a tick, and investigate the influence of climate on nymph fitness predictions. We apply these results to the hypothesized inland migration of I. scapularis from island refugia, evaluating fitness under suboptimal questing strategies and uncertain environmental conditions.

Reconciling the Entomological Hazard and Disease Risk in the Lyme Disease System

Lyme disease (LD) is a commonly cited model for the link between habitat loss and/or fragmentation and disease emergence, based in part on studies showing that forest patch size is negatively related to LD entomological risk. An equivalent relationship has not, however, been shown between patch size and LD incidence (LDI). Because entomological risk is measured at the patch scale, while LDI is generally assessed in relation to aggregate landscape statistics such as forest cover, we posit that the contribution of individual patches to human LD risk has not yet been directly evaluated. We design a model that directly links theoretical entomological risk at the patch scale to larger-scale epidemiological data. We evaluate its predictions for relative LD risk in artificial landscapes with varying composition and configuration, and test its ability to predict countywide LDI in a 12-county region of New York. On simulated landscapes, we find that the model predicts a unimodal relationship between LD incidence and forest cover, mean patch size, and mean minimum distance (a measure of isolation), and a protective effect for percolation probability (a measure of connectivity). In New York, risk indices generated by this model are significantly related to countywide LDI. The results suggest that the lack of concordance between entomological risk and LDI may be partially resolved by this style of model.

Justification for setting the individual animal genotype call rate threshold at eighty-five percent

Data quality of SNP arrays impacts the accuracy and precision of downstream data analyses. One such quality control measure often imposed is a threshold on individual animal call rate. Different call rate thresholds have been applied across studies; little is known, however, about the impact of these thresholds on the quality of the genotype data. The objective of the present study was to investigate the effect of different call rate thresholds on the integrity of the genotypes but also to quantify the contribution of different factors to the variability in animal call rate. Data included 142,342 samples genotyped on a custom Illumina genotype panel from 141,591 dairy and beef cattle; the number of Illumina SNP on the panel was 14,371. The mean animal call rate across all samples was 99.09%; 487 animals had both a low call rate (<99%) and a subsequent high call rate (≥99%) after resampling and regenotyping. Several factors were associated ( < 0.001) with individual call rate including animal sex, the sampling herd, the date of genotyping, the genotyping plate, and the plate well. The genotype and allele concordance between the genotypes of the 487 low- and high-call rate individuals improved at a diminishing rate as mean animal call rate increased. Mean genotype and allele concordance rates of 0.987 and 0.997, respectively, existed when animal call rate was between 85 and 90%, increasing to 0.998 and 0.999, respectively, when animal call rate was between 95 and <99%. The mean within-animal allele concordance rate of rare variants (i.e., minor allele frequency < 0.05) between low and high genotype call rate animals increased when animal call rate improved; an allele concordance rate of 1.00 was achieved when animal call rate was between 85 and <99%. The accuracy of imputation of the nonobserved genotypes in the low-call rate animals improved as animal call rate increased; the mean genotype concordance rate of the imputed nonobserved SNP was 0.41 when animal call rate was <40% but increased to 0.95 when animal call rate was between 95 and <99%. Parentage validation, determined by the count of opposing homozygotes in a parent-progeny pair, was unreliable when animal call rate was <85%. Therefore, to ensure the provision of high-quality genotypes while also considering the cost and inconvenience of resampling and regenotyping, we suggest a minimum animal call rate threshold of 85%.

Novel pH sensing semiconductor for point-of-care detection of HIV-1 viremia

The timely detection of viremia in HIV-infected patients receiving antiviral treatment is key to ensuring effective therapy and preventing the emergence of drug resistance. In high HIV burden settings, the cost and complexity of diagnostics limit their availability. We have developed a novel complementary metal-oxide semiconductor (CMOS) chip based, pH-mediated, point-of-care HIV-1 viral load monitoring assay that simultaneously amplifies and detects HIV-1 RNA. A novel low-buffer HIV-1 pH-LAMP (loop-mediated isothermal amplification) assay was optimised and incorporated into a pH sensitive CMOS chip. Screening of 991 clinical samples (164 on the chip) yielded a sensitivity of 95% (in vitro) and 88.8% (on-chip) at >1000 RNA copies/reaction across a broad spectrum of HIV-1 viral clades. Median time to detection was 20.8 minutes in samples with >1000 copies RNA. The sensitivity, specificity and reproducibility are close to that required to produce a point-of-care device which would be of benefit in resource poor regions, and could be performed on an USB stick or similar low power device.

HLA-associated clinical progression correlates with epitope reversion rates in early human immunodeficiency virus infection

Human immunodeficiency virus type 1 (HIV-1) can evade immunity shortly after transmission to a new host but the clinical significance of this early viral adaptation in HIV infection is not clear. We present an analysis of sequence variation from a longitudinal cohort study of HIV adaptation in 189 acute seroconverters followed for up to 3 years. We measured the rates of variation within well-defined epitopes to determine associations with the HLA-linked hazard of disease progression. We found early reversion across both the gag and pol genes, with a 10-fold faster rate of escape in gag (2.2 versus 0.27 forward mutations/1,000 amino acid sites). For most epitopes (23/34), variation in the HLA-matched and HLA-unmatched controls was similar. For a minority of epitopes (8/34, and generally associated with HLA class I alleles that confer clinical benefit), new variants appeared early and consistently over the first 3 years of infection. Reversion occurred early at a rate which was HLA-dependent and correlated with the HLA class 1-associated relative hazard of disease progression and death (P = 0.0008), reinforcing the association between strong cytotoxic T-lymphocyte responses, viral fitness, and disease status. These data provide a comprehensive overview of viral adaptation in the first 3 years of infection. Our findings of HLA-dependent reversion suggest that costs are borne by some escape variants which may benefit the host, a finding contrary to a simple immune evasion paradigm. These epitopes, which are both strongly and frequently recognized, and for which escape involves a high cost to the virus, have the potential to optimize vaccine design.

Behavior of bird cherry-oat aphid and green peach aphid in relation to potato virus Y transmission

Potato virus Y is transmitted to potato in a nonpersistent manner by many aphid species, some of which do not colonize this crop. The behavior of bird cherry-oat aphid, Rhopalosiphum padi (L.) on potato, Solanum tuberosum L., a plant species that is not colonized by this aphid, was described and compared with that of the potato-colonizing green peach aphid, Myzuspersicae (Sulzer). A higher proportion of winged morph of R. padi than M. persicae left the plant, but aphids that stayed in contact with the plant took the same mean time to initiate the first probe and it lasted the same mean time compared with M. persicae. Electronic penetration graph technique was used to study the probing behavior of the aphids during Potato virus Y (family Potyviridae, genus Potyvirus, PVY) transmission tests. Transmission rate decreased from 29 to 8% when the acquisition time increased from 5 min of continuous probing to 1 h with M. persicae, but it remained low (2 and 1%) with R. padi. Most of the difference in transmission rate between acquisition time with M. persicae and between aphid species was related to the change in the time and behavior taking place between the last cell puncture of the acquisition phase to the first cell puncture of the inoculation phase. Results presented here clearly demonstrated the importance of host plant selection and probing behavior in the transmission of nonpersistent plant viruses. They also stress the need to consider the behavior of the aphid in the design of laboratory tests of virus vector efficacy.

Transmitted drug-resistant HIV-1 in primary HIV-1 infection; incidence, evolution and impact on response to antiretroviral therapy

OBJECTIVES

The aim of the study was to determine the incidence and persistence of transmitted drug-resistant HIV-1 in an incident cohort between 2000 and 2004, and to investigate the impact of transmitted drug-resistant HIV-1 on the response to antiretroviral therapy (ART).

METHODS

A prospective, nonrandomized study was carried out on 140 individuals identified with primary HIV-1 infection (PHI). PHI was defined as an HIV-positive antibody test with an HIV antibody-negative result in the prior 6 months (n = 69); positive HIV DNA in the absence of antibody (n = 30); an evolving titre positive HIV antibody test (n = 23), or an incident 'detuned' assay (B clade viruses only) (n = 18). Genotypic resistance testing was performed at baseline, following ART and annually over a 4-year period.

RESULTS

The prevalence of transmitted drug-resistant HIV-1 infection between January 2000 and June 2004 was nine in 140 (6.0%) and the annual incidence was stable. Seven of these nine patients had a single point mutation conferring single-class drug resistance and the other two patients had multiple mutations conferring multiclass drug resistance (MDR). In eight of the nine cases, mutations conferring drug resistance persisted for more than 12 months off therapy. In contrast to transmitted MDR HIV-1, the virological response to initial ART and CD4 decline were comparable in those with wild-type virus, virus with 'polymorphisms' (secondary mutations) and virus with single drug-resistance mutations.

CONCLUSIONS

The incidence of transmitted drug-resistant HIV remained stable and low over a 4-year period. Although MDR remains rare, its presence significantly affects the response to first-line ART, predisposes towards the accumulation of new resistance mutations and is associated with a more rapid CD4 decline.

Identification of lesion components that influence visual function in age related macular degeneration

AIMS

To explore the relation between lesion composition as assessed by fundus photography and fluorescein angiography with clinical measures of vision in eyes of patients with age related macular degeneration (AMD).

METHODS

A standardised visual function assessment along with colour stereo pair fundus photography was carried out in both eyes of 58 subjects with a confirmed clinical diagnosis of AMD. The size, location, and composition of the macular lesion (blood, exudate, subretinal fluid, pigment, membrane, atrophy, and fibrosis) were measured on the colour photographs using computer assisted image analysis. Of the 58 subjects, 44 also had concurrent fluorescein angiography. Classic and occult choroidal neovascularisation (CNV), blood, blocked fluorescence, fibrosis, geographic atrophy, and the total area of abnormal fluorescence were measured. Multiple linear regression was used to examine the relation between clinical measures of vision and the location and extent of lesion components identified by both colour and fluorescein image capture.

RESULTS

The composition of the macular lesion strongly influenced visual function, with atrophy (p=0.001) and fibrosis (p=0.002) accounting for most of the variation. When the location of the lesion with respect to the fovea was examined, fibrosis within the fovea significantly influenced all clinical measures of vision (p=0.008). The regression model selected the total area of abnormal fluorescence and a composite parameter (a semiquantitative measure of the following characteristics: atrophy, exudates, blood, and fibrosis ) from colour photography (r(2) =0.52) as the variables that explained most of the variation in clinical measures of vision.

CONCLUSIONS

The composition and extent of the macular lesion strongly influences visual function in eyes with AMD. Both colour photography and angiography yielded information, which together explained considerably more of the variation in the clinical measures of vision than either on its own.

An essential role for Rac/Cdc42 GTPases in cerebellar granule neuron survival

Rho family GTPases are critical molecular switches that regulate the actin cytoskeleton and cell function. In the current study, we investigated the involvement of Rho GTPases in regulating neuronal survival using primary cerebellar granule neurons. Clostridium difficile toxin B, a specific inhibitor of Rho, Rac, and Cdc42, induced apoptosis of granule neurons characterized by c-Jun phosphorylation, caspase-3 activation, and nuclear condensation. Serum and depolarization-dependent survival signals could not compensate for the loss of GTPase function. Unlike trophic factor withdrawal, toxin B did not affect the antiapoptotic kinase Akt or its target glycogen synthase kinase-3beta. The proapoptotic effects of toxin B were mimicked by Clostridium sordellii lethal toxin, a selective inhibitor of Rac/Cdc42. Although Rac/Cdc42 GTPase inhibition led to F-actin disruption, direct cytoskeletal disassembly with Clostridium botulinum C2 toxin was insufficient to induce c-Jun phosphorylation or apoptosis. Granule neurons expressed high basal JNK and low p38 mitogen-activated protein kinase activities that were unaffected by toxin B. However, pyridyl imidazole inhibitors of JNK/p38 attenuated c-Jun phosphorylation. Moreover, both pyridyl imidazoles and adenoviral dominant-negative c-Jun attenuated apoptosis, suggesting that JNK/c-Jun signaling was required for cell death. The results indicate that Rac/Cdc42 GTPases, in addition to trophic factors, are critical for survival of cerebellar granule neurons.

Improvements in measures of vision and self-reported visual function after cataract extraction in patients with late-stage age-related maculopathy

PURPOSE

A recent study indicated that patients with cataracts and early age-related maculopathy may benefit from cataract extraction. To ascertain whether cataract extraction in the presence of concurrent advanced age-related maculopathy was also associated with a clear benefit, we studied visual function and self-reported visual functioning in a cohort of 12 patients pre- and post-phakoemulsification. METHODS. All 12 patients had a diagnosis of advanced age-related maculopathy in the eye scheduled for cataract surgery. Preoperative assessment included refraction and recording of best corrected distance and near acuity and contrast sensitivity in both eyes. The Daily Living Tasks Dependent on Vision questionnaire was administered. After phakoemulsification and intraocular lens implantation, all patients were reviewed and assessed.

RESULTS

After surgery, improvement in acuity was recorded in nine operated eyes, whereas acuity remained unchanged in three eyes. Improvement in contrast sensitivity in the operated eye occurred in 10 patients, but in two patients contrast was reduced postoperatively. In terms of self-reported visual functioning, improvement in the ability to undertake many daily living tasks dependent on vision was recorded after cataract surgery.

CONCLUSIONS

Significant improvements in specific areas of self-reported visual functioning and measures of vision were recorded after cataract surgery. During the follow-up period, none of the operated eyes suffered a fall in visual acuity. There was also no evidence of worsening of the pre-existing macular lesion as judged by clinical examination and fundus photography.

Right hepatic lobe donation for living donor liver transplantation: impact on donor quality of life

Adult right hepatic lobe living donor liver transplantation (LDLT) has rapidly gained widespread acceptance as an effective procedure for selected patients with end-stage liver disease. However, there are currently no published data on the effect of this procedure on the quality of life of donors. We report the results of a survey of our living liver transplant donors to determine the effect of right hepatic lobe donation on quality of life. We have performed 30 LDLTs since 1997; 24 of these have a follow-up of 4 months or longer. In August 2000, these patients were sent a questionnaire (including a Medical Outcomes Study 36-Item Short-Form Survey) regarding psychosocial outcomes and symptoms after surgery. Major complications occurred in 4 of 24 patients (16%), and minor complications, in 4 of 24 patients (16%). Complete recovery occurred in 75% of patients at a mean time of 3.4 months. Ninety-six percent of patients returned to the same predonation job after a mean time of 2.4 months, and 66% of patients required a period of light-duty work for a mean of 2.8 months before returning to full-duty work. A change in body image was reported in 42% of patients, and 71% reported mild ongoing symptoms (primarily abdominal discomfort) that they related to the donor surgery for which 29% sought evaluation by a physician. The donor's relationship with the recipient was the same or better in 96% of donors, and the relationship with the donor's significant other was the same or better in 88% of donors. Mean out-of-pocket expenses incurred by donors were $3,660. Sixty-three percent of donors reported experiencing more pain than anticipated. All patients would donate again if necessary, and 96% benefited from the donor experience. In conclusion, (1) all our donors are alive and well after donation; (2) almost all donors were able to return to predonation employment status within a few months; (3) most donors have mild persistent abdominal symptoms, and some donors had a change in body image that they attribute to the donor surgery; and (4) this information should be provided to potential donors so they may better understand the impact of donor surgery.

Recovery and management options for spring/summer chinook salmon in the Columbia River basin

Construction of four dams on the lower Snake River (in northwestern United States) between 1961 and 1975 altered salmon spawning habitat, elevated smolt and adult migration mortality, and contributed to severe declines of Snake River salmon populations. By applying a matrix model to long-term population data, we found that (i) dam passage improvements have dramatically mitigated direct mortality associated with dams; (ii) even if main stem survival were elevated to 100%, Snake River spring/summer chinook salmon (Oncorhynchus tshawytscha) would probably continue to decline toward extinction; and (iii) modest reductions in first-year mortality or estuarine mortality would reverse current population declines.

Interaction of EGF receptor and grb2 in living cells visualized by fluorescence resonance energy transfer (FRET) microscopy

The interaction of activated epidermal growth factor receptor (EGFR) with the Src homology 2 (SH2) domain of the growth-factor-receptor binding protein Grb2 initiates signaling through Ras and mitogen-activated protein kinase (MAP kinase) [1,2]. Activation of EGFRs by ligand also triggers rapid endocytosis of EGF-receptor complexes. To analyze the spatiotemporal regulation of EGFR-Grb2 interactions in living cells, we have combined imaging microscopy with a modified method of measuring fluorescence resonance energy transfer (FRET) on a pixel-by-pixel basis using EGFR fused to cyan fluorescent protein (CFP) and Grb2 fused to yellow fluorescent protein (YFP). Efficient energy transfer between CFP and YFP should only occur if CFP and YFP are less than 50A apart, which requires direct interaction of the EGFR and Grb2 fused to these fluorescent moieties [3]. Stimulation by EGF resulted in the recruitment of Grb2-YFP to cellular compartments that contained EGFR-CFP and a large increase in FRET signal amplitude. In particular, FRET measurements indicated that activated EGFR-CFP interacted with Grb2-YFP in membrane ruffles and endosomes. These results demonstrate that signaling via EGFRs can occur in the endosomal compartment. The work also highlights the potential of FRET microscopy in the study of subcellular compartmentalization of protein-protein interactions in living cells.

Short-term regulation of bile acid uptake by microfilament-dependent translocation of rat ntcp to the plasma membrane

The Na+-taurocholate cotransport polypeptide (ntcp) is the primary transporter for the uptake of bile acids in the liver. The second messenger adenosine 3':5'-cyclic monophosphate (cAMP) rapidly increases ntcp protein concentration in the plasma membrane, yet the mechanism is unknown. To investigate this, HepG2 cells were transiently transfected with a carboxy-terminal-tagged green fluorescence protein (GFP) conjugate of ntcp, and then examined by confocal video microscopy. Transporter activity was directly assayed with 3H-taurocholic acid (TC) scintigraphy. ntcp-GFP targeted to the plasma membrane in transfected cells, and the conjugate protein transported 3H-TC as effectively as unmodified rat ntcp. Stimulation of ntcp-GFP cells with cAMP increased GFP fluorescence in the plasma membrane by 40% (P <.0001) within 2.5 minutes and by 55% within 10 minutes. Similarly, cAMP increased transport of bile acids by 30%. Cytochalasin D, an inhibitor of microfilaments, did not prevent ntcp-GFP from targeting to the plasma membrane, but completely abolished the increase in GFP fluorescence seen in response to cAMP. In contrast, the microtubule inhibitor, nocodazole, prevented development of membrane fluorescence in 48 (96%) of 50 cells. Cells regained plasma membrane fluorescence within 2 hours after nocodazole removal. These findings suggest that targeting of ntcp to the plasma membrane consists of 2 steps: 1) delivery of ntcp to the region of the plasma membrane via microtubules; and 2) insertion of ntcp into the plasma membrane, in a microfilament- and cAMP-sensitive fashion.

Development and evolution of melanophore patterns in fishes of the genus Danio (Teleostei: Cyprinidae)

Pigmentation patterns in vertebrates have become an important model for those interested in mechanisms of pattern determination. I present detailed information on the development of melanophore patterns in the zebrafish, Danio rerio, five close relatives of that species, and an outgroup. The comparison of the ontogeny of melanophore patterns in this group is an important first step towards understanding the developmental basis of the interspecific variation. Pigment patterns in this group range from no distinct patterning at all to stripes of differing numbers and widths to reticulated stripes. Species examined form identical larval patterns and follow a common sequence of events from which different elements are eliminated or altered to produce the variety of patterns seen in the group. As flexion is completed, melanophores move from larval positions onto the flanks of the fish. In D. rerio, D. rerio 'leo,' D. kerri, and D. malabaricus, xanthophores become established on the body of the fish as the melanophores move; erythrophores become established on the flanks of D. albolineatus and D. sp. cf. aequipinnatus. An increase in melanophore number, begun at this time, continues at a higher rate in D. rerio, D. kerri, D. sp. cf. aequipinnatus and Tanichthys albonubes than in the other three species. This results in a greater number of melanophores on adults in those species with a higher rate of melanophore increase. No distinct pattern forms, except on the caudal peduncle, in D. albolineatus. In all other Danio species, melanophore stripes form first below then above the horizontal myoseptum. Additional stripes are added first below then above these initial two stripes. D. kerri develops fewer, wider melanophore stripes than D. rerio. After initial stripe formation, D. malabaricus and D. sp. cf. aequipinnatus both developed vertical pattern elements and reticulations in the melanophore pattern. Differences in patterns between species are similar in several cases to described mutants of the zebrafish, suggesting that some aspects of interspecific pigmentation pattern variation may be under relatively simple genetic control. Copyright 1999 Wiley-Liss, Inc.

Geographic heterogeneity of 4 common worldwide cystic fibrosis non-DF508 mutations in Brazil

Cystic fibrosis (CF) is an autosomal recessive disease caused by at least 750 different mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The frequency of the most common mutation (DF508) in Brazilian patients of European origin is 47%. To determine the frequency of 4 other common CF mutations (G542X, G551D, R553X, and N1303K) in Brazilian patients of European origin, we used direct polymerase chain reaction (PCR) amplification of DNA obtained from dried blood spots on Guthrie cards. The DNA came from 247 non-DF508 chromosomes from 172 Brazilian CF patients ascertained from 5 different states of Brazil. The results show that the 4 mutations account for 17% of the non-DF508 alleles and only 9% of the total number of Brazilian CF alleles. Overall, the frequency of each mutation is different from northern European and North American populations but similar to southern European populations, mainly the Italian and Spanish populations. When Brazilian patients of European origin are grouped according to state of birth, the frequencies of the mutations are significantly different between southern and southeastern states of Brazil. Therefore there are serious implication for risk assessment of DNA-based tests in heterogeneous populations such as Brazilians. Further studies are needed to identify the remaining 44% of CF mutations for the different populations and regions of Brazil.

Low proportion of BRCA1 and BRCA2 mutations in Finnish breast cancer families: evidence for additional susceptibility genes

One hundred breast and breast-ovarian cancer families identified at the Helsinki University Central Hospital in southern Finland and previously screened for mutations in the BRCA2 gene were now analyzed for mutations in the BRCA1 gene. The coding region and splice boundaries of BRCA1 were analyzed by protein truncation test (PTT) and heteroduplex analysis (HA)/SSCP in all 100 families, and 70 were also screened by direct sequencing. Contrary to expectations based on Finnish population history and strong founder effects in several monogenic diseases in Finland, a wide spectrum of BRCA1 and BRCA2 mutations was found. In the BRCA1 gene, 10 different protein truncating mutations were found each in one family. Six of these are novel Finnish mutations and four have been previously found in other European populations. Six different BRCA2 mutations were found in 11 families. Altogether only 21% of the breast cancer families were accounted for by mutations in these two genes. Linkage to both chromosome 17q21 (BRCA1) and 13q12 (BRCA2) was also excluded in a subset of seven mutation-negative families with four or more cases of breast or ovarian cancer. These data indicate that additional breast and breast-ovarian cancer susceptibility genes are likely to be important in Finland.

BRCA1 sequence analysis in women at high risk for susceptibility mutations. Risk factor analysis and implications for genetic testing

CONTEXT

A mutation in the BRCA1 gene may confer substantial risk for breast and/or ovarian cancer. However, knowledge regarding all possible mutations and the relationship between risk factors and mutations is incomplete.

OBJECTIVES

To identify BRCA1 mutations and to determine factors that best predict presence of a deleterious BRCA1 mutation in patients with breast and/or ovarian cancer.

DESIGN

A complete sequence analysis of the BRCA1 coding sequence and flanking intronic regions was performed in 798 women in a collaborative effort involving institutions from the United States, Italy, Germany, Finland, and Switzerland.

PARTICIPANTS

Institutions selected 798 persons representing families (1 person for each family) thought to be at elevated a priori risk of BRCA1 mutation due to potential risk factors, such as multiple cases of breast cancer, early age of breast cancer diagnosis, and cases of ovarian cancer. No participant was from a family in which genetic markers showed linkage to the BRCA1 locus.

MAJOR OUTCOME MEASURES

Sequence variants detected in this sample are presented along with analyses designed to determine predictive characteristics of those testing positive for BRCA1 mutations.

RESULTS

In 102 women (12.8%), clearly deleterious mutations were detected. Fifty new genetic alterations were found including 24 deleterious mutations, 24 variants of unknown significance, and 2 rare polymorphisms. In a subset of 71 Ashkenazi Jewish women, only 2 distinct deleterious mutations were found: 185delAG in 17 cases and 5382insC in 7 cases. A bias in prior reports for mutations in exon 11 was revealed. Characteristics of a patient's specific diagnosis (unilateral or bilateral breast cancer, with or without ovarian cancer), early age at diagnosis, Ashkenazi Jewish ethnicity, and family history of cancer were positively associated with the probability of her carrying a deleterious BRCA1 mutation.

CONCLUSIONS

Using logistic regression analysis, we provide a method for evaluating the probability of a woman's carrying a deleterious BRCA1 mutation for a wide range of cases, which can be an important tool for clinicians as they incorporate genetic susceptibility testing into their medical practice.

Vision screening, eye examination and risk assessment of display screen users in a large regional teaching hospital

In January 1993 the Royal Group of Hospitals Trust, which employs approximately 5000 staff, implemented the Health and Safety (Display Screen Equipment) Northern Ireland Regulations (1992). During 1994 all regular display screen equipment users were offered a vision screening test. In total 571 employees were screened using computerized vision screening software (City Visual Systems Ltd). Risk assessments were completed for 293 display screen work-stations. One hundred and twelve full eye examinations, carried out by optometrists, were performed on those who failed vision screening and on those who specifically requested an optometric assessment. Results indicate that whereas the proportion of users experiencing visual and general symptoms differed markedly from department to department (28-82%), the median number of individuals failing the screening test was 25% (range 9-40%). Those involved in uninterrupted display screen equipment work for prolonged periods reported visual and general work-related symptoms twice as frequently as those who spent less time working with DSE. The outcome of full eye examinations confirmed that less than 5% of display screen users required spectacles solely for display screen use. Work-station analysis indicated that ergonomic problems were common. The authors conclude that the successful management of health risks from display screen equipment requires simultaneous attention to work-place design, working patterns and eye care.

Association of antibodies to Chlamydia trachomatis heat-shock protein 60 kD with chronic nongonococcal urethritis

Ninety male patients with acute nongonococcal urethritis (NGU) who presented for follow-up 10-92 days after initiation of treatment were evaluated. A polymerase chain reaction assay and direct fluorescence antibody test were used to detect Chlamydia trachomatis at presentation and during follow-up. Chlamydial heat-shock protein 60 kD (hsp60) serology with an enzyme-linked immunosorbent assay and C. trachomatis serology with a microimmunofluoresence test were undertaken. In 62 (69%) of the men, evidence of chronic urethritis was noted during follow-up. C. trachomatis was detected in only two patients during follow-up. Chlamydial hsp60 antibody was associated with the development of chronic urethritis between 10 and 92 days after treatment began (P < .04), that is, at 10-29 days (P < .02) and at 30-92 days (P < .008). These results are consistent with the theory that immune response to hsp60 is important in the development of this chronic disease. The results also suggest that chronic NGU is not a consequence of continued production of hsp60 by C. trachomatis.