Recent progress and prospects of dimer and multimer acceptors for efficient and stable polymer solar cells

High power conversion efficiency (PCE) and long-term stability are essential prerequisites for the commercialization of polymer solar cells (PSCs). Small-molecule acceptors (SMAs) are core materials that have led to recent, rapid increases in the PCEs of the PSCs. However, a critical limitation of the resulting PSCs is their poor long-term stability. Blend morphology degradation from rapid diffusion of SMAs with low glass transition temperatures (Tgs) is considered the main cause of the poor long-term stability of the PSCs. The recent emergence of oligomerized SMAs (OSMAs), composed of two or more repeating SMA units (i.e., dimerized and trimerized SMAs), has shown great promise in overcoming these challenges. This innovation in material design has enabled OSMA-based PSCs to reach impressive PCEs near 19% and exceptional long-term stability. In this review, we summarize the evolution of OSMAs, including their research background and recent progress in molecular design. In particular, we discuss the mechanisms for high PCE and stability of OSMA-based PSCs and suggest useful design guidelines for high-performance OSMAs. Furthermore, we reflect on the existing hurdles and future directions for OSMA materials towards achieving commercially viable PSCs with high PCEs and operational stabilities.

High-Performance Organic Electrochemical Transistors Achieved by Optimizing Structural and Energetic Ordering of Diketopyrrolopyrrole-Based Polymers

For optimizing steady-state performance in organic electrochemical transistors (OECTs), both molecular design and structural alignment approaches must work in tandem to minimize energetic and microstructural disorders in polymeric mixed ionic-electronic conductor films. Herein, a series of poly(diketopyrrolopyrrole)s bearing various lengths of aliphatic-glycol hybrid side chains (PDPP-mEG; m = 2-5) is developed to achieve high-performance p-type OECTs. PDPP-4EG polymer with the optimized length of side chains exhibits excellent crystallinity owing to enhanced lamellar and backbone interactions. Furthermore, the improved structural ordering in PDPP-4EG films significantly decreases trap state density and energetic disorder. Consequently, PDPP-4EG-based OECT devices produce a mobility-volumetric capacitance product ([µC*]) of 702 F V-1 cm-1 s-1 and a hole mobility of 6.49 ± 0.60 cm2 V-1 s-1 . Finally, for achieving the optimal structural ordering along the OECT channel direction, a floating film transfer method is employed to reinforce the unidirectional orientation of polymer chains, leading to a substantially increased figure-of-merit [µC*] to over 800 F V-1 cm-1 s-1 . The research demonstrates the importance of side chain engineering of polymeric mixed ionic-electronic conductors in conjunction with their anisotropic microstructural optimization to maximize OECT characteristics.

Low household income increases the risk of tuberculosis recurrence: a retrospective nationwide cohort study in South Korea

OBJECTIVES

We assessed the impact of household income on tuberculosis (TB) recurrence and the long-term impact of TB on household income.

STUDY DESIGN

This was a retrospective nationwide cohort study of patients with drug-susceptible TB (DS-TB) and TB recurrence.

METHODS

Using the South Korean national TB cohort database, we identified a sub-set cohort of patients with newly diagnosed drug-susceptible TB between 2013 and 2016 and tracked their TB recurrence and longitudinal income data from 2007 to 2018. Income levels were evaluated as 'Medical aid' and quintile categories. To assess risk factors associated with TB recurrence, we used a sub-distribution hazard model, adjusting for the competing risks of death.

RESULTS

Of 66,690 patients successfully treated with DS-TB, 2095 (3.1 %) experienced recurrence during a median follow-up of 39 months. The incidence of TB recurrence was 982.1/100,000 person-years, with 50.3 % of the recurrences occurring within 1 year of treatment completion. The risk of TB recurrence increased with decreasing income levels, with the highest risk observed in the lowest income group. The effect of income on TB recurrence was prominent in males but not in females. Overall, patients with TB recurrence experienced a linear decline in income levels, compared with those without recurrence.

CONCLUSIONS

Household income during the initial TB episode was an important risk factor for TB recurrence, particularly in males.

JS04.6.A The landscape of tumor cell states and spatial organization in H3-K27M mutant diffuse midline glioma across age and location

Background

Histone 3 lysine27-to-methionine mutations (H3-K27M) frequently occur in childhood diffuse midline gliomas (DMGs) of the pons, thalamus and spinal cord, presumed to be driven by the specific spatiotemporal context of these midline locations during postnatal development. While most common in the pons and at mid-childhood ages, the same oncohistone mutation is recurrently detected in adult DMGs and throughout different midline regions. The potential heterogeneity of tumors at different ages and in different anatomical locations of the midline are vastly understudied.

Material and Methods

Through dissecting the transcriptomic, epigenomic and spatial architectures of a comprehensive cohort of patient H3-K27M DMGs - spanning the age range from 2-68 years and locations from spinal cord to thalamus - at single cell resolution, we delineate how age- and location-dependent contexts shape glioma cell-intrinsic and -extrinsic features in light of the shared driver mutation.

Results

We identify that oligodendrocyte precursor (OPC)-like cells constitute the stem-like compartment in H3-K27M DMGs across all clinico-anatomical groups, however, depending on location, display varying levels of maturity resembling less differentiated pre-OPCs or more mature OPCs further differentiated along the oligodendroglial lineage. We further demonstrate increased mesenchymal cell states in adult tumors, which we link to age-related differences in glioma-associated immune cell compartments. We for the first time resolve the spatial organization of H3-K27M DMG cell types in intact patient tissues, identifying a local niche of the oligodendroglial lineage.

Conclusion

Our study provides a powerful resource for rational modeling and therapeutic frameworks taking into account determinants of age and location in this lethal glioma group.

Quantifying Contact Patterns: Development and Characteristics of the British Columbia COVID-19 Population Mixing Patterns Survey

Purpose

Several non-pharmaceutical interventions such as physical distancing, self-isolation, a stay-at-home order, hand washing, and schools and businesses closures were implemented in British Columbia (BC) following the first lab-tested case of COVID-19 on January 26, 2020. These interventions were aimed at minimizing in-person contacts that could potentially lead to new COVID-19 infections. The BC COVID-19 Population Mixing Patterns survey (BC-Mix) was established as a surveillance system to measure behaviour and contact patterns in BC over time to inform the timing of the easing/re-imposition of control measures. We describe the BC-Mix survey design and the demographic characteristics of respondents.

Methods & Materials

The ongoing repeated online survey was launched in September 2020. Participants are recruited through a variety of social media platforms including Instagram, Facebook, YouTube, and community group mailing lists. A follow up survey is sent to participants two to four weeks after completing the first iteration. Survey responses are weighted to BC's population by age, sex, geography, and ethnicity to obtain generalizable estimates. A survey completion rate of at least 33% AND a valid response for the sex questionnaire item AND a valid response for age questionnaire item were required for inclusion in weighting and further analysis. Additional indices such as material and social deprivation index, and residential instability are generated using census and location data.

Results

As of June 14, 2021, over 58,000 residents of BC had participated in the survey of which 31,007 survey responses were eligible for analysis. Of the eligible participants, about 60% provided consent for monthly follow up and about 26% provided their personal health numbers for linkage with other healthcare utilization databases. Approximately 51% were females 39% were 55 years or older, 63% identified as white or not a visible minority and 48% had at least a university degree.

Conclusion

The pandemic response is best informed by surveillance systems capable of timely assessment of behaviour patterns. BC-Mix survey respondents represented a large cohort of British Columbians providing near real-time information on behavioural and contact patterns in BC. Data from the BC-Mix survey continues to inform provincial COVID-19-related control measures.

High-Current-Density Organic Electrochemical Diodes Enabled by Asymmetric Active Layer Design

Owing to their outstanding electrical/electrochemical performance, operational stability, mechanical flexibility, and decent biocompatibility, organic mixed ionic-electronic conductors have shown great potential as implantable electrodes for neural recording/stimulation and as active channels for signal switching/amplifying transistors. Nonetheless, no studies exist on a general design rule for high-performance electrochemical diodes, which are essential for highly functional circuit architectures. In this work, generalizable electrochemical diodes with a very high current density over 30 kA cm^-2 are designed by introducing an asymmetric active layer based on organic mixed ionic-electronic conductors. The underlying mechanism on polarity-sensitive balanced ionic doping/dedoping is elucidated by numerical device analysis and in operando spectroelectrochemical potential mapping, while the general material requirements for electrochemical diode operation are deduced using various types of conjugated polymers. In parallel, analog signal rectification and digital logic processing circuits are successfully demonstrated to show the broad impact of circuits incorporating organic electrochemical diodes. It is expected that organic electrochemical diodes will play vital roles in realizing multifunctional soft bioelectronic circuitry in combination with organic electrochemical transistors.

Eco-Friendly Polymer Solar Cells: Advances in Green-Solvent Processing and Material Design

Despite the recent breakthroughs of polymer solar cells (PSCs) exhibiting a power conversion efficiency of over 17%, toxic and hazardous organic solvents such as chloroform and chlorobenzene are still commonly used in their fabrication, which impedes the practical application of PSCs. Thus, the development of eco-friendly processing methods suitable for industrial-scale production is now considered an imperative research focus. This Review provides a roadmap for the design of efficient photoactive materials that are compatible with non-halogenated green solvents (e.g., xylenes, toluene, and tetrahydrofuran). We summarize the recent development of green processing solvents and the processing methods to match with the efficient photoactive materials used in non-fullerene solar cells. We further review progress in the use of more eco-friendly solvents (i.e., water or alcohol) for achieving truly sustainable and eco-friendly PSC fabrication. For example, the concept of water- or alcohol-dispersed nanoparticles made of conjugated materials is introduced. Also, recent important progress and strategies to develop water/alcohol-soluble photoactive materials that completely eliminate the use of conventional toxic solvents are discussed. Finally, we provide our perspectives on the challenges facing the current green processing methods and materials, such as large-area coating techniques and long-term stability. We believe this Review will inform the development of PSCs that are truly clean and renewable energy sources.

Canada's Prosthetic Coverage: a Review of Provincial Prosthetic Policy

The Canadian healthcare system serves as an example of equity and federal service to citizens across the world. However, it is not without its challenges. Prosthetic coverage across Canada is highly variable and largely unable to provide equal coverage for Canadian persons living with amputation. Many persons with limb loss are forced to rely upon personal resources, fundraising, or the charity of non-governmental organizations in order to meet this basic healthcare need. This disparity in the Canadian healthcare system is unusual and largely undescribed in the literature. We thus explore the nature of Canadian healthcare prosthetic coverage across Canada, investigating the variability in coverage, presence of prosthetic coverage policies, clarity of policy, eligibility criteria, and interval of prosthetic replacement. Our findings highlight potential areas for improvement within current Canadian healthcare policy.

Aqueous-Soluble Naphthalene Diimide-Based Polymer Acceptors for Efficient and Air-Stable All-Polymer Solar Cells

Aqueous-processed all-polymer solar cells (aq-APSCs) are reported for the first time by developing a series of water/ethanol-soluble naphthalenediimide (NDI)-based polymer acceptors [P(NDIDEG-T), P(NDITEG-T), and P(NDITEG-T2)]. Polymer acceptors are designed by using the backbones of NDI-bithiophene and NDI-thiophene in combination with nonionic hydrophilic oligoethylene glycol (OEG) side chains that facilitate processability in water/ethanol mixtures. All three polymers exhibit sufficient solubility (20-50 mg mL^-1) in the aqueous medium. The P(NDIDEG-T) polymer with shorter OEG side chains is the most crystalline with the highest electron mobility, enabling the fabrication of efficient aq-APSCs with the maximum power conversion efficiency (PCE) of 2.15%. Furthermore, these aq-APSCs are fabricated under ambient atmosphere by taking advantage of the eco-friendly aqueous process and, importantly, the devices exhibit outstanding air-stability without any encapsulation, as evident by maintaining more than 90% of the initial PCE in the air after 4 days. According to a double cantilever beam test, the interfacial adhesion properties between the active layer and electron/hole transporting layers were remarkably improved by incorporating the hydrophilic OEG-attached photoactive layer, which hinders the delamination of the constituent layers and prevents the increase of series resistance, ultimately leading to enhanced durability under ambient conditions. The combination of increased device stability and minimal environmental impact of these aq-APSCs demonstrates them to be worthy candidates for continued development of scalable polymer solar cells.

Ana o 1 and Ana o 2 cashew allergens share cross-reactive CD4(+) T cell epitopes with other tree nuts

BACKGROUND

Allergies to cashew are increasing in prevalence, with clinical symptoms ranging from oral pruritus to fatal anaphylactic reaction. Yet, cashew-specific T cell epitopes and T cell cross-reactivity amongst cashew and other tree nut allergens in humans remain uncharacterized.

OBJECTIVES

In this study, we characterized cashew-specific T cell responses in cashew-allergic subjects and examined cross-reactivity of these cashew-specific cells towards other tree nut allergens.

METHODS

CD154 up-regulation assay was used to determine immunodominance hierarchy among cashew major allergens at the T cell level. The phenotype, magnitude and functionality of cashew-specific T cells were determined by utilizing ex vivo staining with MHC class II tetramers. Dual tetramer staining and proliferation experiments were used to determine cross-reactivity to other tree nuts.

RESULTS

CD4(+) T cell responses were directed towards cashew allergens Ana o 1 and Ana o 2. Multiple Ana o 1 and Ana o 2 T cell epitopes were then identified. These epitopes elicited either TH 2 or TH 2/TH 17 responses in allergic subjects, which were either cashew unique epitope or cross-reactive epitopes. For clones that recognized the cross-reactive epitope, T cell clones responded robustly to cashew, hazelnut and/or pistachio but not to walnut.

CONCLUSIONS

Phylogenetically diverse tree nut allergens can activate cashew-reactive T cells and elicit a TH 2-type response at an epitope-specific level.

CLINICAL RELEVANCE

Lack of cross-reactivity between walnut and cashew suggests that cashew peptide immunotherapy approach may not be most effective for walnut.

Polyunsaturated fatty acids inhibit Kv1.4 by interacting with positively charged extracellular pore residues

Polyunsaturated fatty acids (PUFAs) modulate voltage-gated K(+) channel inactivation by an unknown site and mechanism. The effects of ω-6 and ω-3 PUFAs were investigated on the heterologously expressed Kv1.4 channel. PUFAs inhibited wild-type Kv1.4 during repetitive pulsing as a result of slowing of recovery from inactivation. In a mutant Kv1.4 channel lacking N-type inactivation, PUFAs reversibly enhanced C-type inactivation (Kd, 15-43 μM). C-type inactivation was affected by extracellular H(+) and K(+) as well as PUFAs and there was an interaction among the three: the effect of PUFAs was reversed during acidosis and abolished on raising K(+) Replacement of two positively charged residues in the extracellular pore (H508 and K532) abolished the effects of the PUFAs (and extracellular H(+) and K(+)) on C-type inactivation but had no effect on the lipoelectric modulation of voltage sensor activation, suggesting two separable interaction sites/mechanisms of action of PUFAs. Charge calculations suggest that the acidic head group of the PUFAs raises the pKa of H508 and this reduces the K(+) occupancy of the selectivity filter, stabilizing the C-type inactivated state.

Molecular phylogenetic reconstruction and taxonomic investigation of eelpouts (Cottoidei: Zoarcales) based on Co-1 and Cyt-b mitochondrial genes

The infraorder Zoarcales (Cottoidei), or eelpouts, includes about 400 species of coldwater fishes concentrated mainly in the North Pacific. To date, the molecular phylogenetic methods in combination with morphological data have significantly contributed to understanding the taxonomic composition of this group and made it possible to confirm/refute validity of some families of obscure origin. In spite of the growing amount of new data on taxonomy and evolution of eelpouts, a consideration of the original and independent data is obviously needed to verify the existing knowledge of this taxon. In this study, which is based on concatenated matrix of Co-1 and Cyt-b mitochondrial genes, as well as relying on the samples from seven families and 45 species of eelpouts, we have reconstructed the phylogeny, which is generally consistent with previous inferences. Despite the resolution of the original data matrix is low, we have demonstrated the monophyletic origin of the families Zoarcidae and Anarhichadidae, as well as Neozoarcidae, previously related to Stichaeidae and recently revised Eulophiidae. The polyphyletic patterns amongst some subfamilies in Stichaeidae have been confirmed, whereas Opisthocentrinae and Pholidae seem to constitute a valid family-level taxon. Our results provide new opportunities with respect to taxonomic relationships in the complex and diverse group of eelpouts , whose part in the tree of life is not covered by recently flourishing multilocus phylogeny of teleost fishes. In light of the data obtained, the necessity of more unified and reproducible approaches to resolve the issues of evolution and taxonomy of such a complex group as Zoarcales becomes more evident.

Large-scale generation of cell-derived nanovesicles

Exosomes are enclosed compartments that are released from cells and that can transport biological contents for the purpose of intercellular communications. Research into exosomes is hindered by their rarity. In this article, we introduce a device that uses centrifugal force and a filter with micro-sized pores to generate a large quantity of cell-derived nanovesicles. The device has a simple polycarbonate structure to hold the filter, and operates in a common centrifuge. Nanovesicles are similar in size and membrane structure to exosomes. Nanovesicles contain intracellular RNAs ranging from microRNA to mRNA, intracellular proteins, and plasma membrane proteins. The quantity of nanovesicles produced using the device is 250 times the quantity of naturally secreted exosomes. Also, the quantity of intracellular contents in nanovesicles is twice that in exosomes. Nanovesicles generated from murine embryonic stem cells can transfer RNAs to target cells. Therefore, this novel device and the nanovesicles that it generates are expected to be used in exosome-related research, and can be applied in various applications such as drug delivery and cell-based therapy.

JNK modulates FOXO3a for the expression of the mitochondrial death and mitophagy marker BNIP3 in pathological hypertrophy and in heart failure

Bcl-2 E1B 19-KDa interacting protein 3 (BNIP3) is a mitochondrial death and mitophagy marker, which is involved in inducing cardiac remodeling post myocardial infarction. In this study, we show that BNIP3 expression increases in stressed cardiomyocytes in vitro and in response to pressure overload in vivo, and that its transcription is directly related to JNK activity. BNIP3 expression gradually increased in the first weeks after pressure overload and peaked at the heart failure stage. Ultrastructurally, the mitochondrial area was inversely proportional to BNIP3 expression. Both JNK and AKT activities increased with pressure overload; however, JNK signaling dominated over AKT signaling for the activation of the transcription factor FOXO3a and for the transcription of its effector, BNIP3. 3-methyladenine attenuated JNK signaling and significantly decreased BNIP3 expression and reversed cardiac remodeling in heart failure. Ultrastructurally, the mitochondrial area was significantly increased in the 3-methyladenine group compared with placebo. Moreover, adenoviral gene delivery of dominant negative JNK in a rat model of pressure overload hypertrophy abolished the increase in BNIP3 expression in response to pressure overload. These results suggest that JNK signaling is a critical modulator of the transcription factor FOXO3a driving the expression of its effector, BNIP3, in heart failure and that JNK, through BNIP3, induces mitochondrial apoptosis and mitophagy.

Relationship of pro-angiogenic factor Cyr61to colorectal cancer development and prognosis

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Background: Angiogenic factorCysteine-rich 61 (Cyr61) is a member of the CCN protein family that has been implicated in diverse biological processes such as cell adhesion, proliferation, angiogenesis, and tumorigenesis. An altered expression of Cyr61 is found to be associated with several human cancers. However, the correlation of expression of Cyr61 protein and clinical features of colorectal cancer remains unknown.

Methods: Cyr61 expression in colorectal cancer and normal tissues was evaluated by Western blot analysis. Immunohistochemical staining was carried out using tissue microassay (TMA) to examine the expression status of Cyr61. Correlations of Cyr61 over-expression with various clinicopathologic factors were also determined. Statistical analysis was performed to explore the links between expression of the Cyr61 and clinicopathological parameters.

Results: On Western blot analysis Cyr61 up-regulation was observed in colorectal cancer tissues (17/21, 80.9%). In 234 colorectal cancers, tumor tissue microarray revealed significantly up-regulated Cyr61 protein expression in colorectal cancer tissues versus normal tissues adjacent to tumor. Cyr61 expression was high in 136 of 234 cases of colorectal carcinomas (58.1%). Cyr61 over-expression was significantly associated with TNM stage (p=0.012) and regional lymph node involvement (p=0.018). Kaplan-Meier survival analysis showed that over-expression of Cyr61 was related to poor survival of colorectal cancer patients (p=0.031). But significant associations were not found between CYR61 expression versus tumor grade, age and gender.

Conclusions: Our results suggest that Cyr61 is highly expressed in colorectal carcinomas and Cyr61 may play a role in the progression of colorectal cancers. Also, Cyr61 might be a new molecular marker to predict the prognosis and serve as valuable targets for therapeutic intervention of patients with colorectal carcinoma.

No significant financial relationships to disclose.

Blocking of acidosis-mediated apoptosis by a reduction of lactate dehydrogenase activity through antisense mRNA expression

Lactic acid produced from the cells is a potential cause of extra- and intracellular acidification. Due to scarce technical tools, lactic acid that leads to acidification could not be reduced and direct evidence of the relationship between metabolic lactate and apoptosis has not yet been elucidated. In this study, we designed a cellular pH regulation system in CHO cells by a reduction of lactate dehydrogenase (LDH) activity through LDH antisense mRNA expression. This inhibited lactate production and, therefore, acidification of the cytosol. Under HCO3(-)-buffered growth conditions, both the parent CHO cells and the engineered CHO cells maintained their extracellular pH and intracellular pH fairly well. However, upon acidification of the cytosol, only the parent CHO cells underwent apoptosis under HCO3(-)-free conditions. In fact, we observed a number of apoptosis-related events only in control cells, including mitochondrial dysfunction, cytochrome c release, and an increase in caspase-3 enzymatic activity.

Synthesis and In vitro binding affinities of 1-azabicyclic compounds as muscarinic ligands

Two series of compounds, 2 and 3, were synthesized and their binding affinities were evaluated for the human recombinant muscarinic M(1) receptor subtype expressed in CHO cells. Comparing their binding affinities for the NMS binding sites and the Oxo-M binding sites, they were assumed as agonists. In particular, compound 2e was a good ligand for the agonist binding sites with an IC(50) of 23 nM, which represents over 1585 times stronger binding than for the antagonist binding sites.

Binding affinities of 3-(3-phenylisoxazol-5-yl)methylidene-1-azabicycles to acetylcholine receptors

A series of 3-(3-phenylisoxazol-5-yl)methylidene-1-azabicycles synthesized showed different binding characteristics to acetylcholine receptors depending on the substituents on the phenyl ring. Small polar substituents gave preferential binding affinity to nicotinic receptors, and large hydrophobic substituents to muscarinic receptors.

G protein-mediated mitogen-activated protein kinase activation by two dopamine D2 receptors

Two isoforms of dopamine D2 receptor, D2L (long) and D2S (short), differ by the insertion of 29 amino acids specific to D2L within the putative third intracellular loop of the receptor, which appears to be important in selectivity for G-protein coupling. We have generated D2L- and D2S-expressing Chinese hamster ovary (CHO) cells, and regulation of the mitogen-activated protein kinase (MAPK) pathway was examined in these cells. Both D2L and D2S mediated a rapid and transient activation of MAPK with dominant activation of p42-kDa MAPK. Pertussis toxin treatment completely abrogated stimulation of MAPK mediated by D2L and D2S, demonstrating that both receptors couple to pertussis toxin-sensitive G proteins in this signaling. Stimulation of MAPK mediated by both D2L and D2S receptor was markedly attenuated by coexpression of the C-terminus of beta-adrenergic receptor kinase (betaARKct), which selectively inhibits Gbetagamma-mediated signal transduction. Further analysis of D2L- and D2S-mediated MAPK activation demonstrated that D2L-mediated MAPK activation was not significantly affected by PKC depletion or partially affected by genistein. In contrast, D2S-mediated MAPK activation was potentially inhibited by PKC depletion and genistein was capable of completely inhibiting D2S-mediated MAPK activation. Together, these results suggest that D2L- and D2S-mediated MAPK activation is predominantly Gbetagamma subunit-mediated signaling and that protein kinase C and tyrosine phosphorylations are involved in these signaling pathways.

Recurrence of bleeding in patients with hypertensive intracerebral hemorrhage

To characterize the recurrence of bleeding in patients who had hypertensive intracerebral hemorrhage (HICH), the authors reviewed 989 patients who underwent treatment for HICH between 1989 and 1995. Fifty-three patients (5.4%) had two episodes of HICH within a median interval of 22.9 +/- 16.3 months (range 1.5-72 months), and of these 3 (5.7%) had three episodes of HICH. The recurrence of bleeding most commonly occurred within 2 years of the first hemorrhage: in 66% of the 53 patients the second hemorrhage occurred soon after the first (within 1 year in 34%, within 1-2 years in 32.1%). The site of the second hemorrhage was different from the initial site in all patients. Only 1 patient had a third hemorrhage in the same site as the second hemorrhage. The common patterns of recurrence were 'ganglionic (putamen/caudate nucleus)-thalamic' in 26.8% and 'ganglionic-ganglionic' in 21.4%. The 'lobar-lobar' pattern was noted in only 2 patients. The volume of the hematoma was increased at the second hemorrhage. The overall mortality was 28.3%. The risk of recurrent hemorrhage significantly increased in the patients who had antihypertensive therapy of less than 3 months after the initial attack compared to those with further long-term therapy (p < 0.005). Long-term regular control for hypertension is needed to prevent recurrent hemorrhage.

A mutational study of the site-specific cleavage of EC83, a multicopy single-stranded DNA (msDNA): nucleotides at the msDNA stem are important for its cleavage

Multicopy single-stranded DNA (msDNA) molecules consist of single-stranded DNA covalently linked to RNA. Such molecules are encoded by genetic elements called retrons. Unlike other retrons, retron EC83 isolated from Escherichia coli 161 produces RNA-free msDNA by site-specific cleavage of msDNA at 5'-TTGA/A-3', where the slash indicates the cleavage site. In order to investigate factors responsible for the msDNA cleavage, retron EC83 was treated with hydroxylamine and colonies were screened for cleavage-negative mutants. We isolated three mutants which were defective in msDNA cleavage and produced RNA-linked msDNA. They were all affected in msd, a gene for msDNA, with a base substitution at the bottom part of the msDNA stem. In contrast, base substitution at and around the cleavage site has no marked effect on msDNA synthesis or its cleavage. From these results, we concluded that the nucleotides at the bottom of the msDNA stem, but not the nucleotides at the cleavage site, play a major role in the recognition and cleavage of msDNA EC83.