Association of long-term exposure to air pollution with chronic sleep deprivation in South Korea: A community-level longitudinal study, 2008-2018

BACKGROUND AND OBJECTIVE

Although there are many findings about the effects of fine particulate matter (PM_2.5) and sleep deprivation on health respectively, the association between PM_2.5 and chronic sleep deprivation has rarely been investigated. Thus, we aimed to investigate this association using a nationwide survey in South Korea.

METHOD

We examined the association between long-term exposure to PM_2.5 and chronic sleep deprivation using a national cross-sectional health survey covering the entire 226 districts in inland South Korea from 2008 to 2018, with a machine learning-based national air pollution prediction model with 1 km² spatial resolution.

RESULTS

Chronic sleep deprivation was positively associated with PM_2.5 in the total population (odds ratio (OR): 1.09, 95% confidence interval (CI): 1.05-1.13) and sub-population (low, middle, high population density areas with OR: 1.127, 1.09, and 1.059, respectively). The association was consistently observed in both sexes (males with OR: 1.09, females with OR: 1.09)) and was more pronounced in the elderly population (OR: 1.12) than in the middle-aged (OR: 1.07) and young (OR: 1.09) populations.

CONCLUSIONS

Our results are consistent with the hypothesis regarding the relationship between long-term PM_2.5 exposure and chronic sleep deprivation, and the study provides quantitative evidence for public health interventions to improve air quality that can affect chronic sleep conditions.

OMA1 mediates local and global stress responses against protein misfolding in CHCHD10 mitochondrial myopathy

Mitochondrial stress triggers a response in the cell’s mitochondria and nucleus, but how these stress responses are coordinated in vivo is poorly understood. Here, we characterize a family with myopathy caused by a dominant p.G58R mutation in the mitochondrial protein CHCHD10. To understand the disease etiology, we developed a knockin (KI) mouse model and found that mutant CHCHD10 aggregated in affected tissues, applying a toxic protein stress to the inner mitochondrial membrane. Unexpectedly, the survival of CHCHD10-KI mice depended on a protective stress response mediated by the mitochondrial metalloendopeptidase OMA1. The OMA1 stress response acted both locally within mitochondria, causing mitochondrial fragmentation, and signaled outside the mitochondria, activating the integrated stress response through cleavage of DAP3-binding cell death enhancer 1 (DELE1). We additionally identified an isoform switch in the terminal complex of the electron transport chain as a component of this response. Our results demonstrate that OMA1 was critical for neonatal survival conditionally in the setting of inner mitochondrial membrane stress, coordinating local and global stress responses to reshape the mitochondrial network and proteome.

HFE H63D Limits Nigral Vulnerability to Paraquat in Agricultural Workers

Paraquat is an herbicide whose use is associated with Parkinson's disease (PD), a neurodegenerative disorder marked by neuron loss in the substantia nigra pars compacta (SNc). We recently observed that the murine homolog to the human H63D variant of the homeostatic iron regulator (HFE) may decrease paraquat-associated nigral neurotoxicity in mice. The present study examined the potential influence of H63D on paraquat-associated neurotoxicity in humans. Twenty-eight paraquat-exposed workers were identified from exposure histories and compared with 41 unexposed controls. HFE genotypes, and serum iron and transferrin were measured from blood samples. MRI was used to assess the SNc transverse relaxation rate (R2*), a marker for iron, and diffusion tensor imaging scalars of fractional anisotropy (FA) and mean diffusivity, markers of microstructural integrity. Twenty-seven subjects (9 exposed and 18 controls) were H63D heterozygous. After adjusting for age and use of other PD-associated pesticides and solvents, serum iron and transferrin were higher in exposed H63D carriers than in unexposed carriers and HFE wildtypes. SNc R2* was lower in exposed H63D carriers than in unexposed carriers, whereas SNc FA was lower in exposed HFE wildtypes than in either unexposed HFE wildtypes or exposed H63D carriers. Serum iron and SNc FA measures correlated positively among exposed, but not unexposed, subjects. These data suggest that H63D heterozygosity is associated with lower neurotoxicity presumptively linked to paraquat. Future studies with larger cohorts are warranted to replicate these findings and examine potential underlying mechanisms, especially given the high prevalence of the H63D allele in humans.

Effects of urbanization on vulnerability to heat-related mortality in urban and rural areas in South Korea: a nationwide district-level time-series study

BACKGROUND

Although urbanization is often an important topic in climate change studies, the complex effect of urbanization on heat vulnerability in urban and rural areas has rarely been studied. We investigated the disparate effects of urbanization on heat vulnerability in urban and rural areas, using nationwide data.

METHODS

We collected daily weather data for all 229 administrative districts in South Korea (2011-17). Population density was applied as an urbanization indicator. We calculated the heat-mortality risk using a distributed lag nonlinear model and analysed the relationship with population density. We also examined district characteristics that can be related to the spatial heterogeneity in heat-mortality risk.

RESULTS

We found a U-shaped association between population density and heat-mortality risk, with the highest risk for rural populations; in urban areas, risk increases with increasing population density. Higher heat-mortality risk was associated with a lower number of hospital beds per person and higher percentage of people requiring recuperation. The association between hospital beds and heat-mortality risk was prominent in high-density urban areas, whereas the association between the percentage of people requiring recuperation and heat-mortality risk was pronounced in rural areas.

CONCLUSIONS

Our findings indicate that the association between population density and heat-mortality risk is different in urban and rural areas, and that district characteristics related to heat-mortality risk also differ by urbanicity. These results can contribute to understanding the complex role of urbanization on heat vulnerability and can provide evidence to policy makers for prioritizing resources.

COVID-19 in South Korea: epidemiological and spatiotemporal patterns of the spread and the role of aggressive diagnostic tests in the early phase

Background

South Korea experienced the novel coronavirus disease (COVID-19) outbreak in the early period; thus data from this country could provide significant implications for global mitigation strategies. This study reports how COVID-19 has spread in South Korea and examines the effects of rapid widespread diagnostic testing on the spread of the disease in the early epidemic phase.

Methods

We collected daily data on the number of confirmed cases, tests and deaths due to COVID-19 from 20 January to 13 April 2020. We estimated the spread pattern with a logistic growth model, calculated the daily reproduction number (R_t) and examined the fatality pattern of COVID-19.

Results

From the start date of the epidemic in Korea (18 February 2020), the time to peak and plateau were 15.2 and 25 days, respectively. The initial R_t was 3.9 [95% credible interval (CI) 3.7 to 4.2] and declined to <1 after 2 weeks. The initial epidemic doubling time was 3.8 days (3.4 to 4.2 days). The aggressive testing in the early days of the epidemic was associated with reduction in transmission speed of COVID-19. In addition, as of 13 April, the case fatality rate of COVID-19 in Korea was 2.1%, suggesting a positive effect of the targeted treatment policy for severe patients and medical resources.

Conclusions

Our findings provide important information for establishing and revising action plans based on testing strategies and severe patient care systems, needed to address the unprecedented pandemic.

VUV spectroscopy in impurity injection experiments at KSTAR using prototype ITER VUV spectrometer

The ITER vacuum ultra-violet (VUV) core survey spectrometer has been designed as a 5-channel spectral system so that the high spectral resolving power of 200-500 could be achieved in the wavelength range of 2.4-160 nm. To verify the design of the ITER VUV core survey spectrometer, a two-channel prototype spectrometer was developed. As a subsequent step of the prototype test, the prototype VUV spectrometer has been operated at KSTAR since the 2012 experimental campaign. From impurity injection experiments in the years 2015 and 2016, strong emission lines, such as Kr xxv 15.8 nm, Kr xxvi 17.9 nm, Ne vii 46.5 nm, Ne vi 40.2 nm, and an array of largely unresolved tungsten lines (14-32 nm) could be measured successfully, showing the typical photon number of 10¹³-10¹⁵ photons/cm² s.

Voluntary exercise can strengthen the circadian system in aged mice

Consistent daily rhythms are important to healthy aging according to studies linking disrupted circadian rhythms with negative health impacts. We studied the effects of age and exercise on baseline circadian rhythms and on the circadian system's ability to respond to the perturbation induced by an 8 h advance of the light:dark (LD) cycle as a test of the system's robustness. Mice (male, mPer2(luc)/C57BL/6) were studied at one of two ages: 3.5 months (n = 39) and >18 months (n = 72). We examined activity records of these mice under entrained and shifted conditions as well as mPER2::LUC measures ex vivo to assess circadian function in the suprachiasmatic nuclei (SCN) and important target organs. Age was associated with reduced running wheel use, fragmentation of activity, and slowed resetting in both behavioral and molecular measures. Furthermore, we observed that for aged mice, the presence of a running wheel altered the amplitude of the spontaneous firing rate rhythm in the SCN in vitro. Following a shift of the LD cycle, both young and aged mice showed a change in rhythmicity properties of the mPER2::LUC oscillation of the SCN in vitro, and aged mice exhibited longer lasting internal desynchrony. Access to a running wheel alleviated some age-related changes in the circadian system. In an additional experiment, we replicated the effect of the running wheel, comparing behavioral and in vitro results from aged mice housed with or without a running wheel (>21 months, n = 8 per group, all examined 4 days after the shift). The impact of voluntary exercise on circadian rhythm properties in an aged animal is a novel finding and has implications for the health of older people living with environmentally induced circadian disruption.

Value of diffusion-weighted imaging in the detection of viable tumour after neoadjuvant chemoradiation therapy in patients with locally advanced rectal cancer: comparison with T2 weighted and PET/CT imaging

OBJECTIVES

To evaluate the added value of diffusion-weighted imaging (DWI) in combination with T(2) weighted imaging (T2WI) compared with T2WI alone or positron emission tomography (PET)/CT for detecting viable tumour after neoadjuvant chemoradiation therapy (CRT) in patients with locally advanced rectal cancer.

METHODS

50 consecutive patients with locally advanced rectal cancer (≥T3 or lymph node positive) who underwent neoadjuvant CRT and subsequent surgery were enrolled in this retrospective study. All patients underwent 3.0 T rectal MRI and PET/CT after completing CRT. For qualitative analysis, two radiologists independently reviewed T2WI alone and DWI with T2WI over a 1-month interval. One nuclear medicine physician reviewed PET/CT images using a five-point scale. Diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for detecting viable tumour were assessed. For quantitative analysis, the apparent diffusion coefficients (ADCs) of the lesions were measured and compared between the viable tumour group and non-viable tumour groups.

RESULTS

For detecting viable tumours, DWI with T2WI improved diagnostic accuracies (Reviewer 1 detected 90%; Reviewer 2, 86%) over T2WI alone (Reviewer 1 detected 76%, p=0.5; Reviewer 2, 64%, p=0.013) or PET/CT (48%, p<0.001). The sensitivity of DWI with T2WI (Reviewer 1 detected 98%; Reviewer 2, 91%) was significantly higher than those of T2WI alone (Reviewer 1 detected 77%; Reviewer 2, 64%) or PET-CT (43%, p<0.05). Only for Reviewer 2 was the NPV of DWI with T2WI (43%) significantly different from that of PET/CT (17%, p<0.05). The specificities and PPVs of DWI with T2WI were not improved over those of T2WI alone or of PET/CT (both p>0.05). The mean ADC of the viable tumour group (0.93 × 10(-3) mm(2) sc(-1)) was significantly lower than that of the non-viable tumour group (1.55 × 10(-3) mm(2) sc(-1), p<0.0001).

CONCLUSION

Adding DWI to T2WI is helpful for detecting viable tumours after neoadjuvant CRT compared with T2WI alone or PET/CT in patients with locally advanced rectal cancer.

High Surface Area Metal Carbide and Metal Nitride Electrodes

Processes for fabricating new high surface area ceramic electrode materials have been developed. These electrode materials have been applied in electrochemical capacitors and related energy storage and conversion devices. Several synthetic approaches have been developed for producing high surface area carbide or nitride active materials. The fabrication methods provide the capability to vary the composition and microstructure of the electrode material. A number of new candidate high surface area electrode materials have been synthesized. Compositional and microstructural information is presented. Electrodes have been evaluated by cyclic voltammetry, chronopotentiometry, and impedance spectroscopy in acidic and basic aqueous electrolyte systems. Single electrode and single cell performance data are presented. Intrinsic properties such as open circuit potential, electrochemical stability and specific capacitance are discussed with respect to electrode composition. The influence on performance of extrinsic factors such as electrode thickness, particle size, and pore structure is also discussed. The performance of these new materials is compared to carbon, with emphasis on advantages with respect to volumetric energy and power density.

Enhanced 'Reading the Mind in the Eyes' in borderline personality disorder compared to healthy controls

BACKGROUND

Borderline personality disorder (BPD) is partly characterized by chronic instability in interpersonal relationships, which exacerbates other symptom dimensions of the disorder and can interfere with treatment engagement. Facial emotion recognition paradigms have been used to investigate the bases of interpersonal impairments in BPD, yielding mixed results. We sought to clarify and extend past findings by using the Reading the Mind in the Eyes Test (RMET), a measure of the capacity to discriminate the mental state of others from expressions in the eye region of the face.

METHOD

Thirty individuals diagnosed with BPD were compared to 25 healthy controls (HCs) on RMET performance. Participants were also assessed for depression severity, emotional state at the time of assessment, history of childhood abuse, and other Axis I and personality disorders (PDs).

RESULTS

The BPD group performed significantly better than the HC group on the RMET, particularly for the Total Score and Neutral emotional valences. Effect sizes were in the large range for the Total Score and for Neutral RMET performance. The results could not be accounted for by demographics, co-occurring Axis I or II conditions, medication status, abuse history, or emotional state. However, depression severity partially mediated the relationship between RMET and BPD status.

CONCLUSIONS

Mental state discrimination based on the eye region of the face is enhanced in BPD. An enhanced sensitivity to the mental states of others may be a basis for the social impairments in BPD.

Nitrogen loss during solar drying of biosolids

Solar drying has been used extensively to dewater biosolids for ease of transportation and to a lesser degree to reduce pathogens prior to land application. The nitrogen in biosolids makes them a relatively inexpensive but valuable source of fertilizer. In this study, nitrogen loss from tilled and untilled biosolids was investigated during the solar drying process. Samples of aerobically and anaerobically digested biosolids during three solar drying experiments were analyzed for their nitrate (NO3-) and ammonium (NH4+) ions concentrations. Nitrogen losses varied depending on the solar drying season and tillage. Although not directly measured, the majority of nitrogen loss occurred through ammonia volatilization; organic nitrogen content (organic N) remained relatively stable for each sample, nitrate concentrations for the majority of samples remained below detectable levels and the decline of ammonium-nitrogen (NH4(+)-N) generally followed the trend of moisture loss in the biosolids.

A phase II trial of perioperative chemotherapy with folinic acid, 5-fluorouracil, and oxaliplatin in potentially resectable gastric cancer with regional lymph node metastasis

4602

Background: Peri-operative chemotherapy in operable advanced gastric cancer (AGC) is still in a controversial area. Results from MAGIC trial suggest that a peri-operative regimen of ECF (epirubicin, cisplatin, 5-FU) decreased tumor size and significantly improved PFS and OS in patients with operable AGC (NEJM 355: 11, 2006). The aim of this study was to evaluate the efficacy and toxicity of folinic acid (FA), infusional 5-fluorouracil (5-FU), and oxaliplatin (modified FOLFOX6), administered every 2 wks in potentially operable AGC with regional lymph node (LN) metastasis. Methods: Previously untreated gastric adenocarcinoma patients with measurable LN on CT scan (clinical stage: cT2 or cT3, N+) were eligible. Staging also included a PET-CT and endoscopic ultrasonography (EUS). Patients received 4 cycles of neoadjuvant therapy with FA 100 mg/m2 (2-hr i.v.), 5-FU 2.4 g/m2 (46-hr continuous infusion), and oxaliplatin 100 mg/m2 (2-hr i.v.), followed by curative radical surgery including D2 dissection and 4 cycles of adjuvant modified FOLFOX6. Clinical responses were assessed by RECIST using CT scan before surgery and early metabolic responses were assessed by PET-CT after 2 cycles of chemotherapy. Results: Thirty-one patients were enrolled from Oct. 2004 to Nov. 2006 and currently, 29 of them are evaluable for response. Median age was 56 yrs (range, 35–69). Most patients had EUS T3N1or2 designation. Of 29 evaluable patients, PR were observed in 19 (66%), SD in 9 (31%), and PD in 1 (3%) patient. Early metabolic responses (SUV decrement = 35% by PET-CT) were significantly correlated with conventional radiographic response (p=0.037). The R0 resection rate was 90% and pathologic CR was 7%. Median follow-up duration was 11.8 mo. and median PFS has not been reached yet. Total 219 cycles were administered. G3/4 neutropenia occurred in 6 cycles (3.0%). Nausea G3/4 occurred in 1 cycle (0.5%) and diarrhea in 1 cycle (0.5%). There were no cases of peripheral neuropathy G3/4 or febrile neutropenia G3/4. Conclusions: Peri-operative chemotherapy with modified FOLFOX6 is very effective and feasible in patients with potentially resectable AGC with regional LN metastasis. Early response can be predicted by PET-CT.

No significant financial relationships to disclose.

Measurement and restoration of the point spread function of fluorescence confocal microscopy

The point spread function of an objective lens of a fluorescence confocal microscope was directly measured by imaging fluorescent beads. We analysed how the measurement of the point spread function was influenced by the diameter of the fluorescent beads and how the restoration technique with a deconvolution algorithm improved the measuring performance. Numerical and experimental results are presented for a typical point spread function and a zero-centred point spread function.

Role of irrigation and wastewater reuse: comparison of subsurface irrigation and furrow irrigation

Two different irrigation systems, subsurface drip irrigation and furrow irrigation, are tested to investigate the level of viral contamination and survival when tertiary effluent is used in arid and semi-arid regions. The effluent was injected with bacteriophages of PRD1 and MS2. A greater number of PRD1 and MS2 were recovered from the lettuce in the subsurface drip-irrigated plots as compared to those in the furrow-irrigated plots. Shallow drip tape installation and preferential water paths through cracks on the soil surface appeared to be the main causes of high viral contamination in subsurface drip irrigation plots, which led to the direct contact of the lettuce stems with the irrigation water which penetrated the soil surface. The water use efficiency of the subsurface drip irrigation system was higher than that of the furrow irrigation system. Thus, subsurface drip irrigation is an efficient irrigation method for vegetable crops in arid and semi-arid regions if viral contamination can be reduced. Deeper installation of drip tapes, frequent irrigations, and timely harvests based on cumulative heat units may further reduce health risks by ensuring viral die-off under various field conditions.

Different suicide inactivation processes for the peroxidase and cyclooxygenase activities of prostaglandin endoperoxide H synthase-1

Prostaglandin endoperoxide H synthases (PGHSs)-1 and -2 have a cyclooxygenase (COX) activity involved in forming prostaglandin G2 (PGG2) from arachidonic acid and an associated peroxidase (POX) activity that reduces PGG2 to PGH2. Suicide inactivation processes are observed for both POX and COX reactions. Here we report COX reaction conditions for PGHS-1 under which complete COX inactivation occurs but with > or = 60% retention of POX activity. The rates of POX inactivation were compared for native oPGHS-1 versus Y385F oPGHS-1, a mutant that cannot form the Tyr385 radical of COX Intermediate II; the rates were the same for both native and Y385F oPGHS-1. Our data indicate that a COX Intermediate II/acyl or product complex is the precursor in COX inactivation. However, another species, probably an Intermediate II-like species but with a radical centered on a tyrosine other than Tyr385, is the immediate precursor for POX inactivation.

Lack of the burst firing of thalamocortical relay neurons and resistance to absence seizures in mice lacking alpha(1G) T-type Ca(2+) channels

T-type Ca(2+) currents have been proposed to be involved in the genesis of spike-and-wave discharges, a sign of absence seizures, but direct evidence in vivo to support this hypothesis has been lacking. To address this question, we generated a null mutation of the alpha(1G) subunit of T-type Ca(2+) channels. The thalamocortical relay neurons of the alpha(1G)-deficient mice lacked the burst mode firing of action potentials, whereas they showed the normal pattern of tonic mode firing. The alpha(1G)-deficient thalamus was specifically resistant to the generation of spike-and-wave discharges in response to GABA(B) receptor activation. Thus, the modulation of the intrinsic firing pattern mediated by alpha(1G) T-type Ca(2+) channels plays a critical role in the genesis of absence seizures in the thalamocortical pathway.

Molecular cloning of the orphanin FQ receptor gene and differential tissue expression of splice variants in rat

Pharmacological and receptor-ligand binding studies of the cloned orphanin FQ (OFQ) receptor suggest that multiple forms of this receptor may exist. To further characterize the OFQ receptor (OFQR), we attempted to isolate the gene encoding this receptor in rat. The OFQR gene exceeds 10 kb in length and contains six exons ranging from 34 to 524 bp that are interrupted by five introns. The ATG translation initiation codon is located in exon 2, and the open reading frame consists of 1283 bp. Primer extension analysis of the gene revealed two major transcription initiation sites: one in the 5' flanking region and the other in intron 1. The rat OFQR gene appeared to be alternatively spliced to yield multiple mRNAs. Four splice variants deleted for exon 1 were expressed only in brain. In contrast, five isoforms containing exon 1 were expressed in various tissues, such as brain, testes, and gastrointestinal tract. These data suggest that unique regions in intron 1 and in the 5' flanking region of the OFQR gene contribute to the regulation of its expression in different tissues.

Expression of semaphorins in developing and regenerating olfactory epithelium

Semaphorins provide signals that guide growing axons to their appropriate destinations. The secreted semaphorin, Sema3A, mediates repulsive effects on axons from various neuronal populations in embryonic rats. The authors localized Sema3A mRNA expression in the primary olfactory pathway during development, in adult rats, and in adult rats that were subjected to a unilateral olfactory bulbectomy. Developing rats at ages from embryonic day 14 (E14) to E19 expressed Sema3A in the olfactory receptor neurons (ORNs) of the olfactory epithelium and in chondrogenic structures surrounding the nasal cavity. In vitro, ORN axons at E14 avoided substrate-bound Sema3A. Low levels of Sema3A expression persisted in the normal adult epithelium both in ORNs scattered throughout the epithelium and in small clusters. Three days after a unilateral olfactory bulbectomy, Sema3A transcript levels increased in regenerating neurons. High levels of Sema3A transcript were found at 1 week postbulbectomy, persisted for 2 weeks, and diminished by 3 weeks. Several other murine semaphorins (Sema4A, Sema4B, and Sema4C) were expressed differentially in the primary olfactory pathway both during development and regeneration. These findings suggest that Sema3A and perhaps other semaphorins play a role in directing ORNs out of the epithelium and to the olfactory bulb, their target structure, during both development and regeneration.

Peroxidase activity in prostaglandin endoperoxide H synthase-1 occurs with a neutral histidine proximal heme ligand

Prostaglandin endoperoxide H synthases-1 and -2 (PGHS-1 and -2) convert arachidonic acid to prostaglandin H(2) (PGH(2)), the committed step in prostaglandin and thromboxane formation. Interaction of peroxides with the heme sites in PGHSs generates a tyrosyl radical that catalyzes subsequent cyclooxygenase chemistry. To study the peroxidase reaction of ovine oPGHS-1, we combined spectroscopic and directed mutagenesis data with X-ray crystallographic refinement of the heme site. Optical and Raman spectroscopy of oxidized oPGHS-1 indicate that its heme iron (Fe(3+)) exists exclusively as a high-spin, six-coordinate species in the holoenzyme and in heme-reconstituted apoenzyme. The sixth ligand is most likely water. The cyanide complex of oxidized oPGHS-1 has a six-coordinate, low-spin ferric iron with a v[Fe-CN] frequency at 445 cm(-)(1); a monotonic sensitivity to cyanide isotopomers that indicates the Fe-CN adduct has a linear geometry. The ferrous iron in reduced oPGHS-1 adopts a high-spin, five-coordinate state that is converted to a six-coordinate, low-spin geometry by CO. The low-frequency Raman spectrum of reduced oPGHS-1 reveals two v[Fe-His] frequencies at 206 and 222 cm(-)(1). These vibrations, which disappear upon addition of CO, are consistent with a neutral histidine (His388) as the proximal heme ligand. The refined crystal structure shows that there is a water molecule located between His388 and Tyr504 that can hydrogen bond to both residues. However, substitution of Tyr504 with alanine yields a mutant having 46% of the peroxidase activity of native oPGHS-1, establishing that bonding of Tyr504 to this water is not critical for catalysis. Collectively, our results show that the proximal histidine ligand in oPGHS-1 is electrostatically neutral. Thus, in contrast to most other peroxidases, a strongly basic proximal ligand is not necessary for peroxidase catalysis by oPGHS-1.

Ages of Late Spectral Type Vega-like Stars

We have estimated the ages of eight late-type Vega-like stars by using standard age-dating methods for single late-type stars, e.g., location on the color-magnitude diagram, Li lambda6708 absorption, Ca ii H and K emission, X-ray luminosity, and stellar kinematic population. With the exception of the very unusual pre-main-sequence star system HD 98800, all the late-type Vega-like stars are the same age as the Hyades cluster (600-800 Myr) or older.

The membrane binding domains of prostaglandin endoperoxide H synthases 1 and 2. Peptide mapping and mutational analysis

Prostaglandin endoperoxide H synthases 1 and 2 (PGHS-1 and -2) are the major targets of nonsteroidal anti-inflammatory drugs. Both isozymes are integral membrane proteins but lack transmembrane domains. X-ray crystallographic studies have led to the hypothesis that PGHS-1 and -2 associate with only one face of the membrane bilayer through a novel, monotopic membrane binding domain (MBD) that is comprised of four short, consecutive, amphipathic alpha-helices (helices A-D) that include residues 74-122 in ovine PGHS-1 (oPGHS-1) and residues 59-108 in human PGHS-2 (hPGHS-2). Previous biochemical studies from our laboratory showed that the MBD of oPGHS-1 lies somewhere between amino acids 25 and 166. In studies reported here, membrane-associated forms of oPGHS-1 and hPGHS-2 were labeled using the hydrophobic, photoactivable reagent 3-trifluoro-3-(m-[(125)I]iodophenyl)diazirine, isolated, and cleaved with AspN and/or GluC, and the photolabeled peptides were sequenced. The results establish that the MBDs of oPGHS-1 and hPGHS-2 reside within residues 74-140 and 59-111, respectively, and thus provide direct provide biochemical support for the hypothesis that PGHS-1 and -2 do associate with membranes through a monotopic MBD. We also prepared HelA, HelB, and HelC mutants of oPGHS-1, in which, for each helix, three or four hydrophobic residues expected to protrude into the membrane were replaced with small, neutral residues. When expressed in COS-1 cells, HelA and HelC mutants exhibited little or no catalytic activity and were present, at least in part, as misfolded aggregates. The HelB mutant retained about 20% of the cyclooxygenase activity of native oPGHS-1 and partitioned in subcellular fractions like native oPGHS-1; however, the HelB mutant exhibited an extra site of N-glycosylation at Asn(104). When this glycosylation site was eliminated (HelB/N104Q mutation), the mutant lacked cyclooxygenase activity. Thus, our mutational analyses indicate that the amphipathic character of each helix is important for the assembly and folding of oPGHS-1 to a cyclooxygenase active form.

Characterization of the glutamate receptor-interacting proteins GRIP1 and GRIP2

The molecular mechanisms underlying the targeting and localization of glutamate receptors at postsynaptic sites is poorly understood. Recently, we have identified a PDZ domain-containing protein, glutamate receptor-interacting protein 1 (GRIP1), which specifically binds to the C termini of AMPA receptor subunits and may be involved in the synaptic targeting of these receptors. Here, we report the cloning of GRIP2, a homolog of GRIP1, and the characterization of the GRIP1 and GRIP2 proteins in the rat CNS. GRIP1 and GRIP2 are approximately 130 kDa proteins that are highly enriched in brain. GRIP1 and GRIP2 are widely expressed in brain, with the highest levels found in the cerebral cortex, hippocampus, and olfactory bulb. Biochemical studies show that GRIP1 and GRIP2 are enriched in synaptic plasma membrane and postsynaptic density fractions. GRIP1 is expressed early in embryonic development before the expression of AMPA receptors and peaks in expression at postnatal day 8-10. In contrast, GRIP2 is expressed relatively late in development and parallels the expression of AMPA receptors. Immunohistochemistry using the GRIP1 antibodies demonstrated that GRIP1 is expressed in neurons in a somatodendritic staining pattern. At the ultrastructural level, DAB and immunogold electromicroscopy studies showed that GRIP1 was enriched in dendritic spines near the postsynaptic density and was expressed in dendritic shafts and in peri-Golgi regions in the neuronal soma. GRIP1 appeared to be clustered at both glutamatergic and GABAergic synapses. These results suggest that GRIP1 and GRIP2 are AMPA receptor binding proteins potentially involved in the targeting of AMPA receptors to synapses. GRIP1 also may play functional roles at both excitatory and inhibitory synapses, as well as in early neuronal development.

RNA-Stimulated ATPase and RNA helicase activities and RNA binding domain of hepatitis G virus nonstructural protein 3

Hepatitis G virus (HGV) nonstructural protein 3 (NS3) contains amino acid sequence motifs typical of ATPase and RNA helicase proteins. In order to examine the RNA helicase activity of the HGV NS3 protein, the NS3 region (amino acids 904 to 1580) was fused with maltose-binding protein (MBP), and the fusion protein was expressed in Escherichia coli and purified with amylose resin and anion-exchange chromatography. The purified MBP-HGV/NS3 protein possessed RNA-stimulated ATPase and RNA helicase activities. Characterization of the ATPase and RNA helicase activities of MBP-HGV/NS3 showed that the optimal reaction conditions were similar to those of other Flaviviridae viral NS3 proteins. However, the kinetic analysis of NTPase activity showed that the MBP-HGV/NS3 protein had several unique properties compared to the other Flaviviridae NS3 proteins. The HGV NS3 helicase unwinds RNA-RNA duplexes in a 3'-to-5' direction and can unwind RNA-DNA heteroduplexes and DNA-DNA duplexes as well. In a gel retardation assay, the MBP-HGV/NS3 helicase bound to RNA, RNA/DNA, and DNA duplexes with 5' and 3' overhangs but not to blunt-ended RNA duplexes. We also found that the conserved motif VI was important for RNA binding. Further deletion mapping showed that the RNA binding domain was located between residues 1383 and 1395, QRRGRTGRGRSGR. Our data showed that the MBP-HCV/NS3 protein also contains the RNA binding domain in the similar domain.

Interaction of the N-ethylmaleimide-sensitive factor with AMPA receptors

Glutamate receptors mediate the majority of rapid excitatory synaptic transmission in the central nervous system (CNS) and play important roles in synaptic plasticity and neuronal development. Recently, protein-protein interactions with the C-terminal domain of glutamate receptor subunits have been shown to be involved in the modulation of receptor function and clustering at excitatory synapses. In this paper, we have found that the N-ethylmaleimide-sensitive factor (NSF), a protein involved in membrane fusion events, specifically interacts with the C terminus of the GluR2 and GluR4c subunits of AMPA receptors in vitro and in vivo. Moreover, intracellular perfusion of neurons with a synthetic peptide that competes with the interaction of NSF and AMPA receptor subunits rapidly decreases the amplitude of miniature excitatory postsynaptic currents (mEPSCs), suggesting that NSF regulates AMPA receptor function.

Interactions of the skin and nervous system

There is increasing experimental evidence that the neurologic system can directly participate in cutaneous inflammation and wound healing. Recent studies indicate that neuropeptides released by cutaneous nerves such as c-fibers can activate a number of target cells including keratinocytes, Langerhans cells, mast cells, and endothelial cells. One such neuropeptide, substance P (SP), is able to specifically bind to murine and human keratinocytes and induce the release of cytokines such as interleukin 1 (IL-1). Other studies demonstrate that SP can also activate mast cells to produce the potent pro-inflammatory cytokine tumor necrosis factor alpha (TNF alpha). More recently, we examined the effect of cutaneous neuropeptides on human dermal microvascular endothelial cell (HDMEC) activities. Our studies indicate that the c-fiber-derived calcitonin gene-related peptide (CGRP) is capable of stimulating HDMEC to secrete the neutrophil chemotactic factor interleukin 8 (IL-8). In addition, SP is able to directly activate HDMEC to express high levels of the important cellular adhesion molecule vascular cellular adhesion molecule 1 (VCAM-1). Thus, these studies support the role that the neurologic system may play in mediating the biologic processes that occur during inflammation and wound healing in the skin.