Staphylococcus aureus foldase PrsA contributes to the folding and secretion of protein A.

BACKGROUND: Staphylococcus aureus secretes a variety of proteins including virulence factors that cause diseases. PrsA, encoded by many Gram-positive bacteria, is a membrane-anchored lipoprotein that functions as a foldase to assist in post-translocational folding and helps maintain the stability of secreted proteins. Our earlier proteomic studies found that PrsA is required for the secretion of protein A, an immunoglobulin-binding protein that contributes to host immune evasion. This study aims to investigate how PrsA influences protein A secretion. RESULTS: We found that in comparison with the parental strain HG001, the prsA-deletion mutant HG001ΔprsA secreted less protein A. Deleting prsA also decreased the stability of exported protein A. Pulldown assays indicated that PrsA interacts with protein A in vivo. The domains in PrsA that interact with protein A are mapped to both the N- and C-terminal regions (NC domains). Additionally, the NC domains are essential for promoting PrsA dimerization. Furthermore, an immunoglobulin-binding assay revealed that, compared to the parental strain HG001, fewer immunoglobulins bound to the surface of the mutant strain HG001ΔprsA. CONCLUSIONS: This study demonstrates that PrsA is critical for the folding and secretion of protein A. The information derived from this study provides a better understanding of virulent protein export pathways that are crucial to the pathogenicity of S. aureus.

Epidemic-Prevention Measures and Health Management in a Nursing Home during the Coronavirus Disease 2019 Pandemic.

This study aimed to investigate the impact of epidemic prevention and isolation policies on residents' health and well-being and assess the effectiveness of implementing intervention measures to maintain their quality of life. This mixed-methods research study involved a retrospective record review of residents' daily life diaries and descriptive statistical analysis. Data were collected between March 2021 and June 2022, and epidemic-prevention measures were implemented using Taiwan's Centers for Disease Control guidelines. Three interventions were developed to address residents' health, social, and rehabilitation needs. Despite an overall infection rate of 10% at various times between 2021 and 2022, there were no reported outbreaks of nosocomial infections. The concept of reablement proved effective in helping residents maintain their independence and physical function, with a maintenance rate of 66.6%, thereby improving their quality of life. By implementing epidemic-prevention measures, we found that proper hand washing and the use of surgical masks were effective in controlling infections. Furthermore, the decline in physical function is a continuous and gradual process for older adults. Even under the restriction of social interaction, it is essential to incorporate rehabilitation plans into residents' daily activities and encourage their active participation, as this promotes improved physical function and enhances their overall quality of life.

Hitchhiking motility of Staphylococcus aureus involves the interaction between its wall teichoic acids and lipopolysaccharide of Pseudomonas aeruginosa.

Staphylococcus aureus, which lacks pili and flagella, is nonmotile. However, it hitchhikes motile bacteria, such as Pseudomonas aeruginosa, to migrate in the environment. This study demonstrated that the hitchhiking motility of S. aureus SA113 was reduced after the tagO, which encodes an enzyme for wall teichoic acids (WTA) synthesis, was deleted. The hitchhiking motility was restored after the mutation was complemented by transforming a plasmid expressing TagO into the mutant. We also showed that adding purified lipopolysaccharide (LPS) to a culture that contains S. aureus SA113 and P. aeruginosa PAO1, reduced the movement of S. aureus, showing that WTA and LPS are involved in the hitchhiking motility of S. aureus. This study also found that P. aeruginosa promoted the movement of S. aureus in the digestive tract of Caenorhabditis elegans and in mice. In conclusion, this study reveals how S. aureus hitchhikes P. aeruginosa for translocation in an ecosystem. The results from this study improve our understanding on how a nonmotile pathogen moves in the environment and spreads in animals.

Relationship of symptom stress, care needs, social support, and meaning in life to quality of life in patients with heart failure from the acute to chronic stages: a longitudinal study.

BACKGROUND: Patients with heart failure (HF) experience continuous changes in symptom distress, care needs, social support, and meaning in life from acute decompensation to chronic phases. The longitudinal relationship between these four factors and quality of life (QOL) was not fully explored. AIMS: To simultaneously investigate the relationship between all factors and QOL from hospitalization to 6 months after discharge, and the impact of the changes in these factors on QOL at different time points. METHODS: A longitudinal design with panel research (4 time points) was used. From January 2017 to December 2019, patients hospitalized due to acute decompensated HF were consecutively enrolled and followed up for 6 months. Patients were interviewed with questionnaires assessing symptom distress, care needs, social support, meaning in life and QOL at hospitalization and 1, 3 and 6 months after discharge. RESULTS: A total of 184 patients completed 6 months of follow-up. From baseline to 6 months, QOL continuously improved along with decreases in symptoms and care needs, but increases in social support and meaning in life. Better QOL was associated with younger age, higher education level, economic independence, less symptom distress and care needs, and stronger meaning in life (p < 0.05). Compared with hospitalization, decreases in care needs and increases in meaning in life at 1, 3 and 6 months were associated with an increase in physical QOL (p < 0.01). The decrease in care needs and increase in meaning in life at 3 months were associated with an increase in mental QOL (p < 0.05). The increase in social support at 6 months was associated with increases in both physical and mental QOL (p < 0.01). Changes in symptom distress were not correlated with changes in QOL from baseline to all time points. In the multivariable analysis, these findings were independent of age, educational level and economic status. CONCLUSIONS: Although symptom distress is associated with QOL after acute decompensated HF, QOL cannot be improved only by improvement in symptoms. With differential duration of improvement in each factor, the integration of alleviation in care needs and strengthening in social support and meaning in life might provide additional benefits in QOL.

Characteristics of HIV-positive pregnant women and HIV- and antiretroviral therapy-exposed fetuses: A case-control study.

INTRODUCTION: This study determined risk factors, obstetric comorbidities, and fetal conditions among HIV-positive mothers to improve their maternal care. METHODOLOGY: This retrospective case-control study included HIV-positive pregnant women 18 years of age or older and age-, parity-, and delivery method-matched HIV-negative controls between 2011 and 2018. Those who had stillbirth were excluded. Baseline demographics, labor process, CD4 count, plasma HIV viral load, and antiretroviral therapy (ART) regimen were recorded. Fetal conditions were recorded as well. RESULTS: Forty HIV-positive women (45 parities; 22 via NSD, 23 via C/S) were included, with 45 HIV-negative parities as controls. Twenty-nine (72.5%) HIV-positive women had illicit drug use. In the HIV-positive group, 17% received ART prior to first perinatal visit, and 75.6% reached viral suppression pre-delivery. Zidovudine and ritonavir-boosted lopinavir were the majorly prescribed ART. Mild perineal lacerations via NSD were observed in HIV-positive women. Fetal body weight was lower in HIV- and ART-exposed fetuses (2665 vs 3010 g, p < 0.001). Preterm delivery PTB (28.9% vs 8.9%, p= 0.015) and small-for gestational age SGA (28.9% vs 8.8%, p = 0.003) rates were higher in the HIV-positive group. There was no vertical transmission of HIV. CONCLUSIONS: HIV-positive women tend to deliver fetuses with low body weight and have higher SGA and PTB rates. Given that most women received zidovudine and protease inhibitors, benefits of newer agents for HIV-positive pregnancies should be studied.

Involvement of Heme in Colony Spreading of Staphylococcus aureus.

Staphylococcus aureus spreads rapidly on the surface of soft agar medium. The spreading depends on the synthesis of biosurfactants, i.e., phenol soluble modulins (PSMs), which facilitate colony spreading of S. aureus. Our earlier study demonstrated that water accumulates in a colony is important to modulate colony spreading of S. aureus. The current study screened a transposon-based mutant library of S. aureus HG001 and obtained four non-spreading mutants with mutations in hemY and ctaA, which are involved in heme synthesis. The spreading ability of these mutants was restored when the mutants are transformed with a plasmid encoding hemY or ctaA, respectively. HemY mutants, which do not synthesize heme B, were able to spread on agar medium supplemented with hemin, a heme B derivative. By contrast, hemin supplementation did not rescue the spreading of the ctaA mutant, which lacks heme B and heme A, indicating that heme A is also critical for colony spreading. Moreover, mutations in hemY and ctaA had little effect on PSMs production but affect ATP production and water accumulation in the colony. In conclusion, this study sheds light on the role of heme synthesis and energy production in the regulation of S. aureus colony spreading, which is important for understanding the movement mechanisms of bacteria lacking a motor apparatus.

The Preliminary Outcome of Applying a Patient Transportation Management System for Non-Emergency Intra-Hospital Transportation of Patients.

In Taiwan, the safety of intra-hospital patient transportation (IHT) is an important issue of patient safety. However, the effects on the quality of patient transportation and the results of patient safety in applying informatics and communication technology were less discussed. The purpose of this study is aimed to understand the current status of IHT events through the patient transportation management system as a reference for further improving the IHT quality.

Grazoprevir/elbasvir in peginterferon alfa plus ribavirin experienced patients with chronic genotype 1 HCV/HIV co-infection: a non-randomized, open-label clinical trial.

Background and aims: We aimed to evaluate the efficacy and tolerability of grazoprevir/elbasvir in patients with chronic genotype 1 hepatitis C virus (HCV) and HIV co-infection who experienced peginterferon alfa plus ribavirin (PegIFN/RBV) (clinicaltrials.gov NCT03098121). Methods: This non-randomized, open-label trial study was conducted in Taoyuan General Hospital. HIV-infected patients were screened for HCV antibody since June 1, 2012, and HCV and HIV co-infected patients were tested for HCV RNA. The subjects who experienced PegIFN/RBV were enrolled in the study, and of whom with chronic genotype 1a or 1b received grazoprevir 100 mg and elbasvir 50 mg in a fixed-dose combination tablet once daily with or without ribavirin for 12 to 16 weeks. Results: Of 2,419 HIV-infected patients, 40 patients with chronic genotype 1 HCV and HIV co-infection who failed PegIFN/RBV treatment were enrolled. Sixteen patients had genotype 1a and 24 patients had genotype 1b, with or without cirrhosis. The median age was 42 (41-47) years, and 5 patients (12.5%) were diagnosed with liver cirrhosis (child Pugh score A). The median CD4 count was 504 cells/µL (321-689). All patients (100%) had HIV viral load <200 copies/mL, and HCV viral load was 6.3 log10 IU/mL (3.98-7.12). At the end of treatment, all patients (100%, 40/40) had undetectable HCV viral load, and 95.0% (38/40) of patients achieved sustained virologic response at 12 weeks. Conclusion: Grazoprevir/elbasvir was effective in genotype 1 patients co-infected with HIV with or without cirrhosis. This finding is consistent with that of previous trials of this regimen in monoinfected population.

Exoproteome Profiling Reveals the Involvement of the Foldase PrsA in the Cell Surface Properties and Pathogenesis of Staphylococcus aureus.

Staphylococcus aureus is a bacterial pathogen that produces and exports many virulence factors that cause diseases in humans. PrsA, a membrane-bound foldase, is expressed ubiquitously in Gram-positive bacteria and required for the folding of exported proteins into a stable and active structure. To understand the involvement of PrsA in posttranslocational protein folding in S. aureus, a PrsA-deficient mutant of S. aureus HG001 was constructed. Using isobaric tags for relative and absolute quantification (iTRAQ)-based mass spectrometry analyses, the exoproteomes of PrsA mutant and wild type S. aureus were comparatively profiled, and 163 cell wall-associated proteins and 67 exoproteins with altered levels have been identified in the PrsA-deficient mutant. Bioinformatics analyses further reveal that prsA deletion altered the amounts of proteins that are potentially involved in the regulation of cell surface properties and bacterial pathogenesis. To determine the relevancy of our findings, we investigated the functional consequence of prsA deletion in S. aureus. PrsA deficiency can enhance bacterial autoaggregation and increase the adhesion ability of S. aureus to human lung epithelial cells. Moreover, mice infected with PrsA-deficient S. aureus had a better survival rate compared with those infected with the wild-type S. aureus. Collectively, our findings reveal that PrsA is required for the posttranslocational folding of numerous exported proteins and critically affects the cell surface properties and pathogenesis of S. aureus.

[Factors and Medical Costs Associated With Fall Events in Hospitalized Patients].

BACKGROUND: Patient falls are a common, adverse event in hospitals that may result in economic and care burdens on the patient and his/her family afterward. PURPOSE: To analyze the factors that relate to falls among inpatients and to estimate the associated days of hospitalization and medical costs. METHODS: The present study used a retrospective matched case-control design to analyze inpatient fall data for 2009 to 2011 from a regional teaching hospital in northern Taipei. We matched fallers and controls according to gender, age ∓ 5 years, and ICD-9-CM (International Classification of Diseases, Ninth Revision, Clinical Modification) code. Data were analyzed using descriptive and inferential statistics. RESULTS: A total of 160 inpatients participated in the present study (80 fallers in the fall group and 80 nonfallers in the control group). The results revealed that fallers had more previous fall experiences and longer hospital stay than nonfallers. Multiple logistic regression analysis revealed that the risk factors that were significantly associated with inpatient falls included: no family accompaniment, use of more than 3 fall-related medications, and no intravenous catheter placement. Results further found that medical costs increased with the degree of injury. Third-degree injuries bore the highest post-fall medical costs of all of the injury-degree categories. The average medical cost for patients with third-degree injuries was 18,257 New Taiwan dollars. CONCLUSIONS / IMPLICATIONS FOR PRACTICE: The findings provide a reference for hospitals to promote patient safety, to prevent the occurrence of inpatient falls, and, ultimately, to reduce fall-associated medical costs.

The expression of fibronectin is significantly suppressed in macrophages to exert a protective effect against Staphylococcus aureus infection.

BACKGROUND: Fibronectin (Fn) plays a major role in the attachment of Staphylococcus aureus to host cells by bridging staphylococcal fibronectin-binding proteins (FnBPs) and cell-surface integrins. A previous study demonstrated that the phagocytosis of S. aureus by macrophages is enhanced in the presence of exogenous Fn. We recently found that FnBPs overexpression also enhances phagocytic activity. The effect of S. aureus infection on the expression of macrophage Fn was investigated. RESULT: The level of Fn secreted by monocytes (THP-1), macrophages, human lung adenocarcinoma (A549) cells, and hepatocellular carcinoma (HepG2) cells in response to S. aureus infection was determined by Western blotting and it was significantly suppressed only in macrophages. The activation of signaling pathways associated with Fn regulation in macrophages and HepG2 cells was also investigated by Western blotting. Erk was activated in both macrophages and HepG2 cells, whereas Src-JNK-c-Jun signaling was only activated in macrophages. A significant decrease in macrophage viability was observed in response to S. aureus infection in the presence of exogenous Fn. CONCLUSION: The Src-JNK-c-Jun signaling pathway was activated in macrophages in response to S. aureus infection and resulted in the suppression of Fn expression. This suppression may play a protective role in macrophages against S. aureus infection. This study provides the first demonstration that Fn is suppressed in macrophages by S. aureus infection.

Tenofovir disoproxil fumarate-associated hypophosphatemia as determined by fractional excretion of filtered phosphate in HIV-infected patients.

INTRODUCTION: Tenofovir disoproxil fumarate (TDF) -containing regimens have been associated with nephrotoxicity and hypophosphatemia in HIV-infected patients. The objective of this study was to assess the possible risk factors for hypophosphatemia and evaluate the relationship between fractional excretion of filtered phosphate (FePi) and hypophosphatemia in TDF users. PATIENT AND METHODS: Patients were enrolled in a prospective cohort study between January 2011 and December 2014. We classified experienced HIV-infected patients (individuals maintained on antiretroviral therapy (ART) for 6 months or more) and naïve patients into 3 treatment groups: TDF-containing ART (group 1), non-TDF-containing ART (never received TDF or had not received TDF in the past 6 months; group 2) and naive to antiretroviral therapy (group 3). Specimens from each individual were assessed for serum phosphate, serum creatinine, urine phosphate, and urine creatinine. Multivariable logistic regression was performed to control for the following variables measured at baseline: eGFR, age, sex, sexual orientation, injection drug use (IDUs), HIV-RNA viral load, and CD4 cell count. RESULTS: The frequency of hypophosphatemia in groups 1, 2, and 3 was 20.2%, 7.2%, and 14.6%, respectively (P = 0.002). FePi above 10% also was significantly associated with hypophosphatemia (P = 0.003; adjusted odds ratio = 2.54). Patients with elevated CD4 cell counts (>500 cells/µL) exhibited a lower risk of hypophosphatemia (P = 0.002; adjusted odds ratio = 0.35). CONCLUSIONS: Hypophosphatemia is a multifactorial etiology; FePi was confirmed as a suggested method to predict the risk of hypophosphatemia in TDF users. Clinical Trial Number: TYGH103011.

Modulation of Staphylococcus aureus spreading by water.

Staphylococcus aureus is known to spread rapidly and form giant colonies on the surface of soft agar and animal tissues by a process called colony spreading. So far, the mechanisms underlying spreading remain poorly understood. This study investigated the spreading phenomenon by culturing S. aureus and its mutant derivatives on Tryptic Soy Agarose (TSA) medium. We found that S. aureus extracts water from the medium and floats on water at 2.5 h after inoculation, which could be observed using phase contrast microscopy. The floating of the bacteria on water could be verified by confocal microscopy using an S. aureus strain that constitutively expresses green fluorescence protein. This study also found that as the density of bacterial colony increases, a quorum sensing response is triggered, resulting in the synthesis of the biosurfactants, phenolic-soluble modulins (PSMs), which weakens water surface tension, causing water to flood the medium surface to allow the bacteria to spread rapidly. This study reveals a mechanism that explains how an organism lacking a flagellar motor is capable of spreading rapidly on a medium surface, which is important to the understanding of how S. aureus spreads in human tissues to cause infections.

High Glucose Concentration Promotes Vancomycin-Enhanced Biofilm Formation of Vancomycin-Non-Susceptible Staphylococcus aureus in Diabetic Mice.

We previously demonstrated that vancomycin treatment increased acquisition of eDNA and enhanced biofilm formation of drug-resistant Staphylococcus aureus through a cidA-mediated autolysis mechanism. Recently we found that such enhancement became more significant under a higher glucose concentration in vitro. We propose that besides improper antibiotic treatment, increased glucose concentration environment in diabetic animals may further enhance biofilm formation of drug-resistant S. aureus. To address this question, the diabetic mouse model infected by vancomycin-resistant S. aureus (VRSA) was used under vancomycin treatment. The capacity to form biofilms was evaluated through a catheter-associated biofilm assay. A 10- and 1000-fold increase in biofilm-bound bacterial colony forming units was observed in samples from diabetic mice without and with vancomycin treatment, respectively, compared to healthy mice. By contrast, in the absence of glucose vancomycin reduced propensity to form biofilms in vitro through the increased production of proteases and DNases from VRSA. Our study highlights the potentially important role of increased glucose concentration in enhancing biofilm formation in vancomycin-treated diabetic mice infected by drug-resistant S. aureus.

Elucidating the crucial role of poly N-acetylglucosamine from Staphylococcus aureus in cellular adhesion and pathogenesis.

Staphylococcus aureus is an important pathogen that forms biofilms on the surfaces of medical implants. Biofilm formation by S. aureus is associated with the production of poly N-acetylglucosamine (PNAG), also referred to as polysaccharide intercellular adhesin (PIA), which mediates bacterial adhesion, leading to the accumulation of bacteria on solid surfaces. This study shows that the ability of S. aureus SA113 to adhere to nasal epithelial cells is reduced after the deletion of the ica operon, which contains genes encoding PIA/PNAG synthesis. However, this ability is restored after a plasmid carrying the entire ica operon is transformed into the mutant strain, S. aureus SA113Δica, showing that the synthesis of PIA/PNAG is important for adhesion to epithelial cells. Additionally, S. carnosus TM300, which does not produce PIA/PNAG, forms a biofilm and adheres to epithelial cells after the bacteria are transformed with a PIA/PNAG-expressing plasmid, pTXicaADBC. The adhesion of S. carnosus TM300 to epithelial cells is also demonstrated by adding purified exopolysaccharide (EPS), which contains PIA/PNAG, to the bacteria. In addition, using a mouse model, we find that the abscess lesions and bacterial burden in lung tissues is higher in mice infected with S. aureus SA113 than in those infected with the mutant strain, S. aureus SA113Δica. The results indicate that PIA/PNAG promotes the adhesion of S. aureus to human nasal epithelial cells and lung infections in a mouse model. This study elucidates a mechanism that is important to the pathogenesis of S. aureus infections.

Social welfare utilization and needs of older adults in Taiwan: survey research.

BACKGROUND: The demand for long-term care for older adults has escalated sharply. A good policy dedicated to the welfare of older adults has improved their quality of life. The purpose of this study was to explore the social welfare utilization and needs of older adults and compare their differences among age groups, genders, and functional dependency levels. METHODS: Three hundred eighty-four stratified, random-sampled Taiwanese community-dwelling older adults were recruited for this survey research. Participants rated their utilization of and needs for the 30 social welfare services provided by the government on a Likert-type scale. RESULTS: The most widely used and needed social welfare services by the older adults were senior monetary stipend and a subsidy for the national health insurance premium. Young-old, male, and functionally independent older adults had more knowledge of the social welfare services than their counterparts. CONCLUSIONS: While designing a comprehensive social welfare system, differing needs of different age groups, genders, and functional dependency levels should be taken into consideration.

Reduced susceptibility to vancomycin in isogenic Staphylococcus aureus strains of sequence type 59: tracking evolution and identifying mutations by whole-genome sequencing.

OBJECTIVES: Vancomycin-intermediate Staphylococcus aureus (VISA) and heterogeneous VISA (hVISA) phenotypes are increasingly reported in methicillin-resistant S. aureus (MRSA) strains of distinct genetic backgrounds. This study tracked genetic evolution during the development of vancomycin non-susceptibility in a prevalent Asian community-associated MRSA clone of sequence type (ST) 59. METHODS: ST59 strains were consecutively isolated from a patient who failed chemotherapy for a septic knee over 15 months. The genetic mutations associated with the VISA phenotype were identified by whole-genome sequencing of two strains, which had the vancomycin-susceptible S. aureus (VSSA) and VISA phenotypes. The mutations were subsequently screened in other strains. By correlating the accumulated mutations with vancomycin susceptibility, genetic evolution was tracked at the whole-genome scale. RESULTS: Nine non-synonymous mutations and two steps of genetic evolution were identified during the development of the VISA phenotype. The first step involved a nonsense mutation in agrC and point mutations at five other loci, which were associated with the VSSA-to-hVISA conversion. Mutations of rpoB and fusA following the use of rifampicin and fusidic acid were identified in the second step of evolution, which corresponded to the development of dual resistance to rifampicin and fusidic acid and the conversion of hVISA to VISA. CONCLUSIONS: In vivo genetic evolution of S. aureus occurred in stepwise order during the development of incremental vancomycin non-susceptibility and was related to the use of antimicrobial agents.

Glucose-6-phosphate dehydrogenase (G6PD)-deficient epithelial cells are less tolerant to infection by Staphylococcus aureus.

Glucose-6-phosphate dehydrogenase (G6PD) is a key enzyme in the pentose phosphate pathway and provides reducing energy to all cells by maintaining redox balance. The most common clinical manifestations in patients with G6PD deficiency are neonatal jaundice and acute hemolytic anemia. The effects of microbial infection in patients with G6PD deficiency primarily relate to the hemolytic anemia caused by Plasmodium or viral infections and the subsequent medication that is required. We are interested in studying the impact of bacterial infection in G6PD-deficient cells. G6PD knock down A549 lung carcinoma cells, together with the common pathogen Staphylococcus aureus, were employed in our cell infection model. Here, we demonstrate that a lower cell viability was observed among G6PD-deficient cells when compared to scramble controls upon bacterial infection using the MTT assay. A significant increase in the intracellular ROS was detected among S. aureus-infected G6PD-deficient cells by observing dichlorofluorescein (DCF) intensity within cells under a fluorescence microscope and quantifying this signal using flow cytometry. The impairment of ROS removal is predicted to enhance apoptotic activity in G6PD-deficient cells, and this enhanced apoptosis was observed by annexin V/PI staining under a confocal fluorescence microscope and quantified by flow cytometry. A higher expression level of the intrinsic apoptotic initiator caspase-9, as well as the downstream effector caspase-3, was detected by Western blotting analysis of G6PD-deficient cells following bacterial infection. In conclusion, we propose that bacterial infection, perhaps the secreted S. aureus α-hemolysin in this case, promotes the accumulation of intracellular ROS in G6PD-deficient cells. This would trigger a stronger apoptotic activity through the intrinsic pathway thereby reducing cell viability when compared to wild type cells.

A repeat sequence causes competition of ColE1-type plasmids.

Plasmid pSW200 from Pantoea stewartii contains 41 copies of 15-bp repeats and has a replicon that is homologous to that of ColE1. Although deleting the repeats (pSW207) does not change the copy number and stability of the plasmid. The plasmid becomes unstable and is rapidly lost from the host when a homoplasmid with the repeats (pSW201) is present. Deleting the repeats is found to reduce the transcriptional activity of RNAIp and RNAIIp by about 30%, indicating that the repeats promote the transcription of RNAI and RNAII, and how the RNAI that is synthesized by pSW201 inhibits the replication of pSW207. The immunoblot analysis herein demonstrates that RNA polymerase ß subunit and σ(70) in the lysate from Escherichia coli MG1655 bind to a biotin-labeled DNA probe that contains the entire sequence of the repeat region. Electrophoretic mobility shift assay also reveals that purified RNA polymerase shifts a DNA probe that contains four copies of the repeats. These results thus obtained reveal that RNA polymerase holoenzyme binds to the repeats. The repeats also exchange RNA polymerase with RNAIp and RNAIIp in vitro, revealing the mechanism by which the transcription is promoted. This investigation elucidates a mechanism by which a plasmid prevents the invasion of an incompatible plasmid and maintains its stability in the host cell during evolution.

Psychological and socioeconomic health of community-dwelling older adults.

Different dimensions of health are intertwined. The purposes of this study were: (1) to investigate the psychological and socioeconomic health status of community-dwelling older adults in Taiwan, and (2) to compare the psychological and socioeconomic health differences among people of different age groups, gender, marital status, and exercise habits. Using stratified random sampling, 384 Taiwanese community-dwelling older adults were recruited for this survey research. Based on the Health Model of Older Adults, seven constructs were measured: (1) psychological health: sleep quality, emotional health, cognitive functioning, and health promotion behaviors; (2) socioeconomic health: social engagement, social support, and financial status. Results showed that most participants were in a good state of psychological and socioeconomic health, except that 38.02% of them suffered from sleep disruptions, and the majority of them were not involved in any social group, nor engaged in any volunteer work. Young-old older adults had better psychological and socioeconomic health than middle-old and old-old older adults. Male older adults had better psychological health than female older adults; however, they had less social engagement and social support than female older adults. Married older adults and exercisers performed better in most of the psychological and socioeconomic health indicators than single/widowed older adults and non-exercisers.