To assess the effectiveness of an intravascular contrast agent, MS‐325, for enhancing the vascular signal in coronary MR angiograms, six minipigs were studied using a three‐dimensional, gradient‐echo ...sequence with retrospective respiratory gating. To suppress the myocardial signal, preparatory RF pulses were applied before data acquisition. With the administration of MS‐325, the blood signal‐to‐noise ratio increased by 97‐276%, depending on the region of interest in which the blood signal was measured and the precontrast imaging sequence structures. The blood/myocardium contrast‐to‐noise ratio also significantly increased. High‐resolution images (0.58 × 0.58 × 1 mm3) obtained from postmortem pig hearts demonstrated the potential delineation of coronary arteries with MS‐325. In conclusion, this study supports further evaluation of the utility of MS‐325 in improving coronary MR angiography in humans.
Working memory (WM) is the ability to keep a limited amount of information “on line” for immediate use during short intervals. Verbal WM has been hypothesized to consist of neuroanatomically ...segregated components, i.e., maintenance (storage, rehearsal, and matching) and manipulation (reordering or updating), corresponding to ventrolateral and dorsolateral prefrontal cortex. Previous imaging studies of maintenance vs manipulation processes in WM have produced inconsistent results, which may have been due to methodological issues such as low statistical power and the use of insertion (subtraction) designs. In the present functional magnetic resonance imaging study we used parametric versions of both a prototypical maintenance task (Sternberg) and a prototypical manipulation task (
n-letter back task) in 21 healthy subjects. Increased signal correlated with load common for both tasks was found in bilateral dorsolateral and anterior prefrontal, left ventrolateral prefrontal, and bilateral parietal regions. Workload × task interactions were found in bilateral dorsolateral prefrontal cortex for manipulation vs maintenance, but also for responding vs encoding (storage) in the maintenance task. Therefore, our data support a functional rather than a neuroanatomical distinction between maintenance and manipulation, given our finding that these tasks differentially activate virtually identical systems.
Abstract
STUDY QUESTION
Which genetic factors regulate female propensity for giving birth to spontaneous dizygotic (DZ) twins?
SUMMARY ANSWER
We identified four new loci, GNRH1, FSHR, ZFPM1, and ...IPO8, in addition to previously identified loci, FSHB and SMAD3.
WHAT IS KNOWN ALREADY
The propensity to give birth to DZ twins runs in families. Earlier, we reported that FSHB and SMAD3 as associated with DZ twinning and female fertility measures.
STUDY DESIGN, SIZE, DURATION
We conducted a genome-wide association meta-analysis (GWAMA) of mothers of spontaneous dizygotic (DZ) twins (8265 cases, 264 567 controls) and of independent DZ twin offspring (26 252 cases, 417 433 controls).
PARTICIPANTS/MATERIALS, SETTING, METHODS
Over 700 000 mothers of DZ twins, twin individuals and singletons from large cohorts in Australia/New Zealand, Europe, and the USA were carefully screened to exclude twins born after use of ARTs. Genetic association analyses by cohort were followed by meta-analysis, phenome wide association studies (PheWAS), in silico and in vivo annotations, and Zebrafish functional validation.
MAIN RESULTS AND THE ROLE OF CHANCE
This study enlarges the sample size considerably from previous efforts, finding four genome-wide significant loci, including two novel signals and a further two novel genes that are implicated by gene level enrichment analyses. The novel loci, GNRH1 and FSHR, have well-established roles in female reproduction whereas ZFPM1 and IPO8 have not previously been implicated in female fertility. We found significant genetic correlations with multiple aspects of female reproduction and body size as well as evidence for significant selection against DZ twinning during human evolution. The 26 top single nucleotide polymorphisms (SNPs) from our GWAMA in European-origin participants weakly predicted the crude twinning rates in 47 non-European populations (r = 0.23 between risk score and population prevalence, s.e. 0.11, 1-tail P = 0.058) indicating that genome-wide association studies (GWAS) are needed in African and Asian populations to explore the causes of their respectively high and low DZ twinning rates. In vivo functional tests in zebrafish for IPO8 validated its essential role in female, but not male, fertility. In most regions, risk SNPs linked to known expression quantitative trait loci (eQTLs). Top SNPs were associated with in vivo reproductive hormone levels with the top pathways including hormone ligand binding receptors and the ovulation cycle.
LARGE SCALE DATA
The full DZT GWAS summary statistics will made available after publication through the GWAS catalog (https://www.ebi.ac.uk/gwas/).
LIMITATIONS, REASONS FOR CAUTION
Our study only included European ancestry cohorts. Inclusion of data from Africa (with the highest twining rate) and Asia (with the lowest rate) would illuminate further the biology of twinning and female fertility.
WIDER IMPLICATIONS OF THE FINDINGS
About one in 40 babies born in the world is a twin and there is much speculation on why twinning runs in families. We hope our results will inform investigations of ovarian response in new and existing ARTs and the causes of female infertility.
STUDY FUNDING/COMPETING INTEREST(S)
Support for the Netherlands Twin Register came from the Netherlands Organization for Scientific Research (NWO) and The Netherlands Organization for Health Research and Development (ZonMW) grants, 904-61-193, 480-04-004, 400-05-717, Addiction-31160008, 911-09-032, Biobanking and Biomolecular Resources Research Infrastructure (BBMRI.NL, 184.021.007), Royal Netherlands Academy of Science Professor Award (PAH/6635) to DIB, European Research Council (ERC-230374), Rutgers University Cell and DNA Repository (NIMH U24 MH068457-06), the Avera Institute, Sioux Falls, South Dakota (USA) and the National Institutes of Health (NIH R01 HD042157-01A1) and the Genetic Association Information Network (GAIN) of the Foundation for the National Institutes of Health and Grand Opportunity grants 1RC2 MH089951. The QIMR Berghofer Medical Research Institute (QIMR) study was supported by grants from the National Health and Medical Research Council (NHMRC) of Australia (241944, 339462, 389927, 389875, 389891, 389892, 389938, 443036, 442915, 442981, 496610, 496739, 552485, 552498, 1050208, 1075175). L.Y. is funded by Australian Research Council (Grant number DE200100425). The Minnesota Center for Twin and Family Research (MCTFR) was supported in part by USPHS Grants from the National Institute on Alcohol Abuse and Alcoholism (AA09367 and AA11886) and the National Institute on Drug Abuse (DA05147, DA13240, and DA024417). The Women’s Genome Health Study (WGHS) was funded by the National Heart, Lung, and Blood Institute (HL043851 and HL080467) and the National Cancer Institute (CA047988 and UM1CA182913), with support for genotyping provided by Amgen. Data collection in the Finnish Twin Registry has been supported by the Wellcome Trust Sanger Institute, the Broad Institute, ENGAGE—European Network for Genetic and Genomic Epidemiology, FP7-HEALTH-F4-2007, grant agreement number 201413, National Institute of Alcohol Abuse and Alcoholism (grants AA-12502, AA-00145, AA-09203, AA15416, and K02AA018755) and the Academy of Finland (grants 100499, 205585, 118555, 141054, 264146, 308248, 312073 and 336823 to J. Kaprio). TwinsUK is funded by the Wellcome Trust, Medical Research Council, Versus Arthritis, European Union Horizon 2020, Chronic Disease Research Foundation (CDRF), Zoe Ltd and the National Institute for Health Research (NIHR) Clinical Research Network (CRN) and Biomedical Research Centre based at Guy’s and St Thomas’ NHS Foundation Trust in partnership with King’s College London. For NESDA, funding was obtained from the Netherlands Organization for Scientific Research (Geestkracht program grant 10000-1002), the Center for Medical Systems Biology (CSMB, NVVO Genomics), Biobanking and Biomolecular Resources Research Infrastructure (BBMRI-NL), VU University’s Institutes for Health and Care Research (EMGO+) and Neuroscience Campus Amsterdam, University Medical Center Groningen, Leiden University Medical Center, National Institutes of Health (NIH, ROI D0042157-01A, MH081802, Grand Opportunity grants 1 RC2 Ml-1089951 and IRC2 MH089995). Part of the genotyping and analyses were funded by the Genetic Association Information Network (GAIN) of the Foundation for the National Institutes of Health. Computing was supported by BiG Grid, the Dutch e-Science Grid, which is financially supported by NWO. Work in the Del Bene lab was supported by the Programme Investissements d’Avenir IHU FOReSIGHT (ANR-18-IAHU-01). C.R. was supported by an EU Horizon 2020 Marie Skłodowska-Curie Action fellowship (H2020-MSCA-IF-2014 #661527). H.S. and K.S. are employees of deCODE Genetics/Amgen. The other authors declare no competing financial interests.
TRIAL REGISTRATION NUMBER
N/A.
The "accelerator hypothesis" predicts that fatness is associated with an earlier age at onset of type 1 diabetes. We tested the hypothesis using data from the SEARCH for Diabetes in Youth study.
...Subjects were 449 youth aged <20 years at diagnosis who had positive results for diabetes antibodies measured 3-12 months after diagnosis (mean 7.6 months). The relationships between age at diagnosis and fatness were examined using BMI as measured at the SEARCH visit and reported birth weight, both expressed as SD scores (SDSs).
Univariately, BMI SDS was not related to age at diagnosis. In multiple linear regression, adjusted for potential confounders, a significant interaction was found between BMI SDS and fasting C-peptide (FCP) on onset age (P < 0.0001). This interaction remained unchanged after additionally controlling for number and titers of diabetes antibodies. An inverse association between BMI and age at diagnosis was present only among subjects with FCP levels below the median (<0.5 ng/ml) (regression coefficient -7.9, P = 0.003). A decrease of 1 SDS in birth weight (639 g) was also associated with an approximately 5-month earlier age at diagnosis (P = 0.008), independent of sex, race/ethnicity, current BMI, FCP, and number of diabetes antibodies.
Increasing BMI is associated with younger age at diagnosis of type 1 diabetes only among those U.S. youth with reduced beta-cell function. The intrauterine environment may also be an important determinant of age at onset of type 1 diabetes.
The effect of O6-benzylguanine, O6-(p-chlorobenzyl)guanine, and O6-(p-methylbenzyl)guanine on the sensitivity of various human tumor cell lines to alkylating agents is evaluated. The sensitivity of ...human colon tumor cells, HT29, to the chloroethylating agents, 1,3-bis(2-chloroethyl)-1-nitrosourea, 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea, 2-chloroethyl(methylsulfonyl) methanesulfonate (clomesone), and chlorozotocin was increased by pretreatment for 2 h with 25 microM of each analogue. O6-Benzylguanine was slightly more effective as a sensitizer in HT29 cells than the p-chlorobenzyl and p-methylbenzyl analogues. However, all analogues sensitized SF767 glioma cells to the cytotoxic effects of 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea, 1,3-bis(2-chloroethyl)-1-nitrosourea, and clomesone to the same degree. Both cell lines were sensitized to the methylating agents streptozotocin and 5-(3-methyl-1-triazeno)imidazole-4-carboxamide, the active intermediate of 5-(3,3-dimethyl-1-triazenyl)imidazole-4-carboxamide, by pretreatment with 10 microM O6-benzylguanine for 2 h. The number of Raji cells surviving 50 microM clomesone decreased 3-fold upon pretreatment for 2 h with 1 microM O6-benzylguanine. The degree of enhancement was dependent on the amount of alkyltransferase protein present in cell lines. For example, HT29 cells (alkyltransferase activity, 381 fmol/mg protein) exhibited a greater degree of enhancement when treated with O6-benzylguanine than SF767 (77 fmol/mg protein) and M19-MEL melanoma (36 fmol/mg protein) cells. There was no enhancement observed in mer- cell lines, U251 (less than 2 fmol/mg protein), and BE (3 fmol/mg protein), or with alkylating agents which did not produce a cytotoxic lesion at the O6 position of guanine in DNA such as cisplatin or 4-hydroperoxycyclophosphamide. Our studies suggest that O6-benzylguanine analogues may have utility in mer+ tumors as an adjuvant to a variety of alkylating agents which produce a toxic lesion at the O6 position of guanine.
The basic helix–loop–helix (bHLH) transcription factor
Math5 (
Atoh7) is required for retinal ganglion cell (RGC) and optic nerve development. Using
Math5-lacZ knockout mice, we have identified an ...additional expression domain for
Math5 outside the eye, in functionally connected structures of the central auditory system. In the adult hindbrain, the cytoplasmic
Math5-lacZ reporter is expressed within the ventral cochlear nucleus (VCN), in a subpopulation of neurons that project to medial nucleus of the trapezoid body (MNTB), lateral superior olive (LSO), and lateral lemniscus (LL). These cells were identified as globular and small spherical bushy cells based on their morphology, abundance, distribution within the cochlear nucleus (CN), co-expression of Kv1.1, Kv3.1b and Kcnq4 potassium channels, and projection patterns within the auditory brainstem.
Math5-
lacZ is also expressed by cochlear root neurons in the auditory nerve. During embryonic development,
Math5-lacZ was detected in precursor cells emerging from the caudal rhombic lip from embryonic day (E)12 onwards, consistent with the time course of CN neurogenesis. These cells co-express MafB and are post-mitotic.
Math5 expression in the CN was verified by mRNA
in situ hybridization, and the identity of positive neurons was confirmed morphologically using a
Math5-Cre BAC transgene with an alkaline phosphatase reporter.
The hindbrains of
Math5 mutants appear grossly normal, with the exception of the CN. Although overall CN dimensions are unchanged, the
lacZ-positive cells are significantly smaller in
Math5 −/− mice compared to
Math5 +/− mice, suggesting these neurons may function abnormally. The auditory brainstem response (ABR) of
Math5 mutants was evaluated in a BALB/cJ congenic background. ABR thresholds of
Math5 −/− mice were similar to those of wild-type and heterozygous mice, but the interpeak latencies for Peaks II–IV were significantly altered. These temporal changes are consistent with a higher-level auditory processing disorder involving the CN, potentially affecting the integration of binaural sensory information.
We have previously shown that O6-benzylguanine can be used to deplete cells of the DNA repair protein O6-alkylguanine-DNA alkyltransferase and to enhance the sensitivity of human glioma (SF767) and ...colon tumor (HT29) cells to the cytotoxic effects of alkylnitrosoureas. In the present study, the combination of O6-benzylguanine and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) was evaluated in vitro to determine the number of DNA interstrand cross-links formed and in vivo to compare the therapeutic index with that of BCNU alone. The number of DNA interstrand cross-links, as measured by alkaline elution, was increased in HT29 cells treated with 10 microM O6-benzylguanine for 2 h prior to BCNU exposure compared to cells treated with BCNU only. The number of single strand breaks was not increased by prior exposure to O6-benzylguanine. To evaluate the therapeutic index, HT29 and SF767 cells were grown as xenografts in nude mice and the tumor growth rate after treatment with BCNU alone was compared with the rate after treatment with O6-benzylguanine and BCNU. Treatment was administered i.p. when tumors reached 100-200 mm3. For animals bearing HT29 xenografts that were treated with 60 mg/kg O6-benzylguanine 1 h prior to 20 mg/kg BCNU, the average time for tumor volume to increase by 200% was 25 days, compared to 10 days for animals treated with 20 mg/kg BCNU alone. For animals bearing SF767 xenografts, the tumor growth of controls was not significantly different from that of animals treated with O6-benzylguanine alone or BCNU alone up to the maximally tolerated dose (50 mg/kg). For these 3 groups, the average time for tumors to reach 300 mm3 was 9-12 days. However, when animals were treated with 80 mg/kg O6-benzylguanine 1 h prior to receiving 20 mg/kg BCNU tumor size did not increase for at least 21 days. Our studies demonstrate that the therapeutic index of BCNU can be increased when given in combination with O6-benzylguanine.
Objective To assess, among overweight non-hispanic black adolescents the relationship of changes in plasma retinol binding protein 4 (RBP4) over 3 years to changes in insulin resistance (IR) and 4 ...associated cardiometabolic risks. Study design Nested, retrospective study of 51 overweight, post-pubertal non-Hispanic black participants in the Princeton School District Study. Participants were in the top (worsening IR) or bottom (improved IR) quartile for 3-year change in IR. RBP4 was measured by quantitative Western blot with frozen plasma. Regression analyses adjusted for age, sex, and adiposity (baseline and change). Three measures of adiposity were assessed (waist circumference, body mass index, and weight) in separate regression models. Results RBP4 increased in one third (n = 17). In logistic regression analyses, increased RBP4 was associated with significantly higher odds of worsening as opposed to improved IR independent of age, sex, or adiposity. Odds ratios were 5.6 (weight, P = .024), 6.0 (BMI, P = .025) and 7.4 (waist circumference, P = .015). Initial RBP4 (β = 0.81, P = .005) and change in RBP4 (β = 0.56, P = .046) also predicted change in triglycerides, but not change in high-density lipoprotein–cholesterol, low-density lipoprotein–cholesterol, or fibrinogen. Conclusion This retrospective cohort study provides evidence that RBP4 may be a mechanism through which obesity influences insulin resistance and hypertriglyceridemia in overweight postpubertal black youth and suggests utility of RBP4 as a biomarker of risk.
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