Preclinical Efficacy and Safety of a Human Embryonic Stem Cell-Derived Midbrain Dopamine Progenitor Product, MSK-DA01

Parkinson's disease is characterized by the loss of dopaminergic neurons in the substantia nigra leading to disabling deficits. Dopamine neuron grafts may provide a significant therapeutic advance over current therapies. We have generated midbrain dopamine neurons from human embryonic stem cells and manufactured large-scale cryopreserved dopamine progenitors for clinical use. After optimizing cell survival and phenotypes in short-term studies, the cell product, MSK-DA01, was subjected to an extensive set of biodistribution, toxicity, and tumorigenicity assessments in mice under GLP conditions. A large-scale efficacy study was also performed in rats with the same lot of cells intended for potential human use and demonstrated survival of the grafted cells and behavioral amelioration in 6-hydroxydopamine lesioned rats. There were no adverse effects attributable to the grafted cells, no obvious distribution outside the brain, and no cell overgrowth or tumor formation, thus paving the way for a future clinical trial.

0212 Questionnaire Assessment of Intraindividual Variability in Sleep: Inconsistent Sleep Can Be Worse Than Short Average Sleep

Introduction

The consequences of short sleep are well-documented, but recent evidence indicates that night-to-night consistency in sleep may be just as important. For the current work, we developed an intraindividual variability in sleep (IIV) questionnaire to make IIV measurement possible in single-time-point studies. We investigated whether self-reported IIV explained unique variance in sleep quality and health beyond average total sleep time (TST), focusing on a critical transition period (first semester of college) in which high variability was predicted.

Methods

First-semester college students (N=126, Mage=18.28, 75.40% females) completed an IIV questionnaire in which participants indicated their average sleep duration, then estimated how much their sleep duration deviated from their average duration for each day of a typical week. We quantified IIV as the mean day-to-day change in sleep. Participants also completed standard questionnaires on global sleep quality, social jetlag, daytime sleepiness, depression, and stress.

Results

Participants reported substantial IIV in their sleep durations (M=1.77 hours, SD=0.86) that was largely distinguishable from measures of social jetlag (r=.25) and average TST (r=-.18). Patterns of IIV differed across race/ethnicities: in white/Asian students, IIV was strongly associated with social jetlag (r=-.44) whereas in underrepresented minority students, IIV and social jetlag were separate constructs (r=-.03), suggesting that fluctuations in the latter group occur across all days of the week. Greater IIV was associated with significantly worse global sleep quality (r=.24, p=.01), stress (r=.20, p=.03), and depression, r=.20, p=.03). These associations were significant after adjusting for average TST, and only marginally reduced when controlling for social jetlag.

Conclusion

IIV in sleep/wake patterns can be captured using a questionnaire, and such measurement provides unique explanatory power to understanding sleep quality and mental health. Future research is needed to compare IIV questionnaire data to actigraphy data and to understand the underlying mechanisms by which inconsistent sleep detrimentally affects individuals.

Support

National Science Foundation (NSF 1920730)

0369 Sleep Disparities are Established by the First Month of College

Introduction

Short and poor quality sleep are particularly common in college students, likely impacting their ability to persist and succeed in difficult courses. In the current study, we investigated demographic-based sleep differences (sleep disparities) and demographic-based academic differences (achievement gaps) in first-semester college students, with the goal of informing whether sleep disparities contribute to achievement gaps.

Methods

From 2017 to 2018, first-semester undergraduate students at Baylor University completed the New2BU Survey [N=6,048, 61.9% female, 18.7% first-generation, 23.8% underrepresented racial/ethnic minority (URM)]. Data collection occurred within three to five weeks of classes beginning. The survey included self-reported weekday total sleep time (TST), which we classified as short sleep (≤6.9 hours), normal sleep (7-9 hours), or long sleep (>9 hours). Semester GPA data were obtained from university records for students’ first 4 semesters.

Results

There was evidence for both achievement gaps and sleep disparities. The risk for short sleep was increased in female students (p<.001; OR=1.20, 95%CI: 1.08-1.33), first-generation students (p=.02; OR=1.17, 95%CI: 1.03-1.33), and URM students (p<.001; OR=1.32, 95%CI: 1.16-1.50). The risk for long sleep increased substantially in first-generation students (p=.003, OR=1.92, 95%CI: 1.25-2.97) and URM students (p<.001; OR=2.41, 95%CI: 1.57-3.70), but not in female students (OR=0.88, 95%CI: 0.59-1.30). First-generation and URM students showed a 0.2-0.3 GPA reduction each semester relative to comparison groups (ps<.001), but short sleep and long sleep predicted GPA data up to four semesters later. Sleep-GPA correlations were modest in size (rs=.10-.14), but remained significant even after controlling for numerous demographic variables, high school GPA, and college entrance test scores.

Conclusion

Sleep disparities are noteworthy within the first month of college, and predictive of academic performance across four semesters. Addressing sleep health in all students—but particularly female, first-generation, and URM students—may increase academic success, bridge achievement gaps, and reduce health disparities.

Support

National Science Foundation (DRL 1920730)

0391 Gateways, Disparities, and Finals Week, Oh My! Translating Sleep Science from the Laboratory to the Classroom

Introduction

Organic chemistry can be an insurmountable “gateway” course for otherwise-qualified students in pre-health pathways. Recent data indicate that organic chemistry increases drop-out risk for females and underrepresented minority students (URMs), raising the provocative possibility that sleep disparities are an underrecognized contributor to achievement gaps in gateway STEM courses.

Methods

In Study 1, 481 students enrolled in organic chemistry courses completed sleep questionnaires at the beginning, midpoint, and end of the semester. In Study 2, non-chemistry majors were randomly assigned to normal sleep (8 hours) or sleep restriction (5.5 hours) before taking an organic chemistry virtual lecture and test. In Study 3, 35 students wore actigraphy for five nights and could earn extra credit on a mid-semester test by averaging ≥8 hours of sleep; actigraphy sleep durations were compared to 40 active-control students who only received sleep education.

Results

In Study 1 (classroom), URM and female students earned lower organic chemistry grades than comparison students, p<.001. Baseline weekday sleep duration predicted test grades across the semester, and students who improved their weekday sleep subsequently improved their organic chemistry grades. In Study 2 (laboratory), mild sleep loss impaired meta-cognitive judgments of organic chemistry learning, a potential causal mechanism for reduced persistence in chemistry courses. In Study 3 (classroom), when better sleep behaviors were incentivized by extra credit, students slept an hour longer/night than control groups (7.8 vs 6.8 hours, p<.001). These benefits persisted 1 month later into finals week when sleep behaviors were not externally incentivized (7.3 vs 6.3 hours, p=.001). Improving sleep improved performance on difficult short answer questions after correcting for pre-final grades (Madjusted=78% vs 72%, p=.04).

Conclusion

Sleep disparities contribute to achievement gaps in gateway STEM courses, but incentives can reverse poor sleep habits. University administrators should develop and implement behavioral change programs to reduce sleep disparities.

Support

National Science Foundation (DRL 1920730)

International Nosocomial Infection Control Consortium report, data summary of 50 countries for 2010-2015: Device-associated module

BACKGROUND

We report the results of International Nosocomial Infection Control Consortium (INICC) surveillance study from January 2010-December 2015 in 703 intensive care units (ICUs) in Latin America, Europe, Eastern Mediterranean, Southeast Asia, and Western Pacific.

METHODS

During the 6-year study period, using Centers for Disease Control and Prevention National Healthcare Safety Network (CDC-NHSN) definitions for device-associated health care-associated infection (DA-HAI), we collected prospective data from 861,284 patients hospitalized in INICC hospital ICUs for an aggregate of 3,506,562 days.

RESULTS

Although device use in INICC ICUs was similar to that reported from CDC-NHSN ICUs, DA-HAI rates were higher in the INICC ICUs: in the INICC medical-surgical ICUs, the pooled rate of central line-associated bloodstream infection, 4.1 per 1,000 central line-days, was nearly 5-fold higher than the 0.8 per 1,000 central line-days reported from comparable US ICUs, the overall rate of ventilator-associated pneumonia was also higher, 13.1 versus 0.9 per 1,000 ventilator-days, as was the rate of catheter-associated urinary tract infection, 5.07 versus 1.7 per 1,000 catheter-days. From blood cultures samples, frequencies of resistance of Pseudomonas isolates to amikacin (29.87% vs 10%) and to imipenem (44.3% vs 26.1%), and of Klebsiella pneumoniae isolates to ceftazidime (73.2% vs 28.8%) and to imipenem (43.27% vs 12.8%) were also higher in the INICC ICUs compared with CDC-NHSN ICUs.

CONCLUSIONS

Although DA-HAIs in INICC ICU patients continue to be higher than the rates reported in CDC-NSHN ICUs representing the developed world, we have observed a significant trend toward the reduction of DA-HAI rates in INICC ICUs as shown in each international report. It is INICC's main goal to continue facilitating education, training, and basic and cost-effective tools and resources, such as standardized forms and an online platform, to tackle this problem effectively and systematically.

Boundary lipids in the nicotinic acetylcholine receptor microenvironment

The structural and functional properties of the nicotinic acetylcholine receptor (AChR), the archetype molecule in the superfamily of Cys-looped ligand-gated ion channels, are strongly dependent on the lipids in the vicinal microenvironment. The influence on receptor properties is mainly exerted by the AChR-vicinal ("shell" or "annular") lipids, which occur in the liquid-ordered phase as opposed to the more disordered and "fluid" bulk membrane lipids. Fluorescence studies from our laboratory have identified discrete sites for fatty acids, phospholipids, and cholesterol on the AChR protein, and electron-spin resonance spectroscopy has enabled the establishment of the stoichiometry and selectivity of the shell lipid for the AChR and the disclosure of lipid sites in the AChR transmembrane region. Experimental evidence supports the notion that the interface between the protein moiety and the adjacent lipid shell is the locus of a variety of pharmacologically relevant processes, including the action of steroids and other lipids. I surmise that the outermost ring of M4 helices constitutes the boundary interface, most suitable to convey the signals from the lipid microenvironment to the rest of the transmembrane region, and to the channel inner ring in particular.

Cdc7-Drf1 kinase links chromosome cohesion to the initiation of DNA replication in Xenopus egg extracts

To establish functional cohesion between replicated sister chromatids, cohesin is recruited to chromatin before S phase. Cohesin is loaded onto chromosomes in the G1 phase by the Scc2-Scc4 complex, but little is known about how Scc2-Scc4 itself is recruited to chromatin. Using Xenopus egg extracts as a vertebrate model system, we showed previously that the chromatin association of Scc2 and cohesin is dependent on the prior establishment of prereplication complexes (pre-RCs) at origins of replication. Here, we report that Scc2-Scc4 exists in a stable complex with the Cdc7-Drf1 protein kinase (DDK), which is known to bind pre-RCs and activate them for DNA replication. Immunodepletion of DDK from Xenopus egg extracts impairs chromatin association of Scc2-Scc4, a defect that is reversed by wild-type, but not catalytically inactive DDK. A complex of Scc4 and the N terminus of Scc2 is sufficient for chromatin loading of Scc2-Scc4, but not for cohesin recruitment. These results show that DDK is required to tether Scc2-Scc4 to pre-RCs, and they underscore the intimate link between early steps in DNA replication and cohesion.

Crystal structure of the GINS complex and functional insights into its role in DNA replication

The GINS complex, which contains the four subunits Sld5, Psf1, Psf2, and Psf3, is essential for both the initiation and progression of DNA replication in eukaryotes. GINS associates with the MCM2-7 complex and Cdc45 to activate the eukaryotic minichromosome maintenance helicase. It also appears to interact with and stimulate the polymerase activities of DNA polymerase epsilon and the DNA polymerase alpha-primase complex. To further understand the functional role of GINS, we determined the crystal structure of the full-length human GINS heterotetramer. Each of the four subunits has a major domain composed of an alpha-helical bundle-like structure. With the exception of Psf1, each of the other subunits has a small domain containing a three-stranded beta-sheet core. Each full-length protein in the crystal has unstructured regions that are all located on the surface of GINS and are probably involved in its interaction with other replication factors. The four subunits contact each other mainly through alpha-helices to form a ring-like tetramer with a central pore. This pore is partially plugged by a 16-residue peptide from the Psf3 N terminus, which is unique to some eukaryotic Psf3 proteins and is not required for tetramer formation. Removal of these N-terminal 16 residues of Psf3 from the GINS tetramer increases the opening of the pore by 80%, suggesting a mechanism by which accessibility to the pore may be regulated. The structural data presented here indicate that the GINS tetramer is a highly stable complex with multiple flexible surface regions.

Human SHPRH is a ubiquitin ligase for Mms2-Ubc13-dependent polyubiquitylation of proliferating cell nuclear antigen

Human SHPRH gene is located at the 6q24 chromosomal region, and loss of heterozygosity in this region is seen in a wide variety of cancers. SHPRH is a member of the SWI/SNF family of ATPases/helicases, and it possesses a C(3)HC(4) RING motif characteristic of ubiquitin ligase proteins. In both of these features, SHPRH resembles the yeast Rad5 protein, which, together with Mms2-Ubc13, promotes replication through DNA lesions via an error-free postreplicational repair pathway. Genetic evidence in yeast has indicated a role for Rad5 as a ubiquitin ligase in mediating the Mms2-Ubc13-dependent polyubiquitylation of proliferating cell nuclear antigen. Here we show that SHPRH is a functional homolog of Rad5. Similar to Rad5, SHPRH physically interacts with the Rad6-Rad18 and Mms2-Ubc13 complexes, and we show that SHPRH protein is a ubiquitin ligase indispensable for Mms2-Ubc13-dependent polyubiquitylation of proliferating cell nuclear antigen. Based on these observations, we predict a role for SHPRH in promoting error-free replication through DNA lesions. Such a role for SHPRH is consistent with the observation that this gene is mutated in a number of cancer cell lines, including those from melanomas and ovarian cancers, which raises the strong possibility that SHPRH function is an important deterrent to mutagenesis and carcinogenesis in humans.

Proximity-induced activation of human Cdc34 through heterologous dimerization

Cdc34 is an E2-conjugating enzyme required for catalyzing the polyubiquitination reaction mediated by the Skp1.CUL1.F-box (SCF) protein E3 ubiquitin (Ub) ligase. Here, we show that the activity of human Cdc34 in the Ub-Ub ligation reaction was enhanced dramatically by SCF's core Ub ligase module, composed of a heterodimeric complex formed by the ROC1 RING finger protein and the CUL1 C terminus that contains a Nedd8 moiety covalently conjugated at K720. Unexpectedly, we found that N-terminal fusion of a GST moiety to human Cdc34 generated dimeric GST-Cdc34 that was constitutively active in supporting the assembly of K48-linked polyUb chains independently of SCF. Furthermore, fusion of a FK506-binding protein (FKBP) to the N terminus of human Cdc34 yielded FKBP-Cdc34 that was induced to form a dimer upon treatment with the chemical inducer AP20187. The AP20187-induced dimeric form of FKBP-Cdc34 was substantially more active than the monomer in catalyzing Ub-Ub ligation. Thus, juxtaposition of human Cdc34 activates its catalytic capability, suggesting that the SCF-mediated polyubiquitination reaction may require the conversion of Cdc34 from an inactive monomer to a highly active dimeric form.

Atomic force microscopic analysis of the binding of the Schizosaccharomyces pombe origin recognition complex and the spOrc4 protein with origin DNA

In eukaryotes, the initiation of DNA replication requires the interaction between origin sequences and the origin recognition complex (ORC), which is highly conserved. In this report, atomic force microscopy (AFM) was used to examine the binding of Schizosaccharomyces pombe (sp) ORC and the spOrc4 protein with the sp autonomously replicating sequence 1 (ars1). AFM imaging revealed that spORC binding to ars1 occurred solely through spOrc4p and depended on the N-terminal AT-hook domains present in spOrc4p. At high molar ratios of spORC (or spOrc4p alone) to DNA (6:1), all of the input ars1 was bound in a one protein complex to one plasmid manner. Restriction digestion and AFM analysis of protein-DNA fragments revealed the presence of two binding sites in ars1. One site mapped to a region centered at nucleotide 838 of ars1 previously detected by DNase I protection that was reported to be essential for the autonomously replicating sequence activity of ars1. The second site mapped to a previously uncharacterized region centered at nucleotide 1148. AFM showed that the length of the DNA fragment complexed with either spORC or spOrc4p was shortened by approximately 140 bp, suggesting the wrapping of two turns of the DNA around the spOrc4p alone as well as the spOrc4p in spORC. We also show that treatment of the spORC (spOrc4p)-ars1 complex with topoisomerase I induced a negative shift in the topoisomer distribution. These findings suggest that the binding of spORC to origin DNA alters the structure of the DNA. Thus, in the case of spORC, due to its unusual spOrc4p, at least two factors are likely to influence ars1 activation. These include the selective binding of the complex to A- and T-rich regions and the alteration of the DNA structure due to its wrapping around spOrc4p.

Structure and activity associated with multiple forms of Schizosaccharomyces pombe DNA polymerase delta

DNA polymerase delta (Pol delta) isolated from Schizosaccharomyces pombe (sp) consists of at least four subunits, Pol3, Cdc1, Cdc27, and Cdm1. We have reconstituted the four-subunit complex by simultaneously expressing these polypeptides in baculovirus-infected insect cells. The properties of the purified cloned spPol delta were identical to the native spPol delta isolated from S. pombe cells. In addition, we also isolated a three-subunit complex containing Pol3, Cdc1, and Cdm1. Both three- and four-subunit complexes required replication factor C and proliferating cell nuclear antigen for DNA replication. However, in the presence of low levels of polymerase complexes, the three-subunit complex was less efficient than the four-subunit complex in supporting DNA replication. The inefficient synthesis of DNA by the three-subunit complex can be remedied by the addition of Cdc27, the subunit missing in the three-subunit complex. Gel filtration analysis demonstrated that the three-subunit complex is a monomer of the heterotrimer (Pol3, Cdc1, and Cdm1) and that the four-subunit complex is a dimer of the heterotetramer (Pol3, Cdc1, Cdc27, and Cdm1), similar to the structure of native spPol delta. We have further shown that Cdc1 and Cdc27 interact to form a heterodimeric complex. Gel filtration studies indicate that the structure of this complex is dimeric. These observations suggest that the Cdc27 subunit may play an important role contributing to the dimerization of Pol delta.

AP1 enhances polyomavirus DNA replication by promoting T-antigen-mediated unwinding of DNA

An early step in the initiation of polyomavirus DNA replication is viral large-T-antigen-mediated unwinding of the origin. We report that components of the AP1 transcription factor, Fos and Jun, interact with T antigen in vitro to enhance unwinding of the viral origin. This provides a biochemical basis for the capacity of AP1 to activate viral DNA replication in vivo.

Effect of sample freezing on the isolation of Mycoplasma spp. from the clitoral fossa of the mare

The growth of Mycoplasma equigenitalium and Mycoplasma subdolum from specimens collected from the clitoral fossa of each of four Standardbred mares was not diminished by freezing of the specimens in liquid nitrogen (-196 degrees C) for up to 30 days when compared to samples cultured immediately.

Recovery of Mycoplasma spp. from the Reproductive Tract of the Mare during the Estrous Cycle

The sites in the genital tract from which mycoplasmas could be recovered at various stages of the estrous cycle were studied in five Standardbred mares naturally infected with Mycoplasma. Mycoplasma equigenitalium and Mycoplasma subdolum were most frequently isolated from the clitoral fossa as compared to the vagina, cervix, and uterus. The lowest isolation prevalence was observed in the uterus. The recovery of Mycoplasma spp. from the clitoral fossa did not differ at any stage of the estrous cycle; however, recovery from the vagina, cervix, and uterus was variable during the cycle and more organisms were recovered on the day of ovulation than at any other time. From these results it was concluded that the clitoral fossa is the most likely "ecological niche" for Mycoplasma spp. in the mare. Ureaplasmas were not isolated.