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.

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.

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.

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.

[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.

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.

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.

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.

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.

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.

Inhibitory effects of 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranose on biofilm formation by Staphylococcus aureus.

1,2,3,4,6-Penta-O-galloyl-ß-D-glucopyranose (PGG) is an active ingredient in plants that are commonly used in Chinese medicine to treat inflammation. We demonstrate here that PGG, at 6.25 µM, does not inhibit the growth of Staphylococcus aureus, and yet it prevents biofilm formation on polystyrene and polycarbonate surfaces. At the same concentration, PGG is not toxic to human epithelial and fibroblast cells. PGG has an IB50 value, i.e., the PGG concentration that inhibits 50% biofilm formation, of 3.6 µM. The value is substantially lower than that of N-acetylcysteine, iodoacetamide, and N-phenyl maleimide, which are known to inhibit biofilm formation by S. aureus. Biochemical and scanning electron microscopy results also reveal that PGG inhibits initial attachment of the bacteria to solid surface and the synthesis of polysaccharide intercellular adhesin, explaining how PGG inhibits biofilm formation. The results of this study demonstrate that coating PGG on polystyrene and silicon rubber surfaces with polyaniline prevents biofilm formation, indicating that PGG is highly promising for clinical use in preventing biofilm formation by S. aureus.

Transmissibility and temporal changes of 2009 pH1N1 pandemic during summer and fall/winter waves.

BACKGROUND: In order to compare the transmissibility of the 2009 pH1N1 pandemic during successive waves of infections in summer and fall/winter in the Northern Hemisphere, and to assess the temporal changes during the course of the outbreak in relation to the intervention measures implemented, we analyze the epidemiological patterns of the epidemic in Taiwan during July 2009-March 2010. METHODS: We utilize the multi-phase Richards model to fit the weekly cumulative pH1N1 epidemiological data (numbers of confirmed cases and hospitalizations) as well as the daily number of classes suspended under a unique "325" partial school closing policy in Taiwan, in order to pinpoint the turning points of the summer and fall/winter waves, and to estimate the reproduction numbers R for each wave. RESULTS: Our analysis indicates that the summer wave had slowed down by early September when schools reopened for fall. However, a second fall/winter wave began in late September, approximately 4 weeks after the school reopened, peaking at about 2-3 weeks after the start of the mass immunization campaign in November. R is estimated to be in the range of 1.04-1.27 for the first wave, and between 1.01-1.05 for the second wave. CONCLUSIONS: Transmissibility of the summer wave in Taiwan during July-early September, as measured by R, was lower than that of the earlier spring outbreak in North America and Europe, as well as that of the winter outbreak in Southern Hemisphere. Furthermore, transmissibility during fall/winter in Taiwan was noticeably lower than that of the summer, which is attributable to population-level immunity acquired from the earlier summer wave and also to the intervention measures that were implemented prior to and during the fall/winter wave.

Correction of severely inverted nipple with telescope method.

For female patients, an inverted nipple can result in functional problems, such as difficulty breast feeding, and emotional difficulties because of self-consciousness about the condition. Numerous surgical techniques for inverted nipple correction have been proposed, but none of the methods provides a reliable outcome. Most methods involve releasing retractile ducts and fibrous bands and adding bulk at the base of nipple; however, these techniques can cause injury to normal lactiferous ducts and sensory dysfunction. Herein we describe a "telescope method," performed under local anesthesia, which consists of making a circumferential incision, pulling out the nipple, and tightening the nipple base. With this technique, most lactiferous ducts and parallel sensory nerves that travel through the nipple base are not injured, and the procedure is associated with a less visible scar and nipple deformity than other methods. We report on 23 nipples of 17 patients that were successfully treated with this method. There was no recurrence of nipple inversion or sensory disturbance in the follow-up period. This technique is a simple, safe, and reliable method for the correction of severely inverted nipples.

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.

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.

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.

Stabilization of pSW100 from Pantoea stewartii by the F conjugation system.

Plasmid pSW100 is 1 of the 13 plasmids from Pantoea stewartii subsp. stewartii SW2 which has a replicon that resembles that of ColE1. This work uses a pSW100 derivative, pSW140K, to study how the pSW100 replicon is stably maintained in its hosts. Our results indicate that although pSW140K is stable in Escherichia coli HB101, the plasmid is rapidly lost in another E. coli strain, DH5alpha, indicating that the genetic background of an E. coli strain affects the stability of pSW140K. Mutagenesis of E. coli HB101 with EZ::TN revealed that mutations in traC, traF, traG, traN, and traV, which encode the components of the sex pilus assembly, reduce plasmid stability. Furthermore, this work identified that a 38-bp region located immediately upstream of the RNAII promoter is critical to the maintenance of plasmid stability in E. coli HB101. TraC binds to the region, and in addition, deleting the region destabilizes the plasmid. Furthermore, inserting this 38-bp fragment into a plasmid that contains the minimal replicon from pSW200 stabilizes the plasmid in E. coli HB101. Fluorescence in situ hybridization and immunofluorescence staining also revealed that derivatives of pSW100, pSW128A, and TraC are colocalized in cells, suggesting that pSW100 may use the sex pilus assembly as a partition apparatus to ensure the even distribution of the plasmid during cell division, which may thus maintain the plasmid's stability.

Sphingosine 1-phosphate affects cytokine-induced apoptosis in rat pancreatic islet beta-cells.

Cytokines mediate pancreatic islet beta-cell apoptosis and necrosis, leading to loss of insulin secretory capacity and type 1 diabetes mellitus. The cytokines, IL-1beta and interferon-gamma, induced terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling (TUNEL) staining of rat islet cells within 48 h by about 25-30%, indicative of apoptosis and/or necrosis. Sphingosine 1-phosphate (S1P) at nanomolar concentrations significantly reduced islet cell cytokine-induced TUNEL staining. Similar effects were observed in INS-1 cells. The dihydro analog of S1P also reduced the percentage of TUNEL stained islet and INS-1 cells, whereas the S1P receptor antagonist BML-241 blocked the protective effects. Pertussis toxin did not affect the S1P protective response. In the presence of a phospholipase C antagonist, U73122, there was significant inhibition of the S1P protective effects against apoptosis/necrosis. S1P stimulated INS-1 cell protein kinase C activity. Carbamylcholine chloride acting through muscarinic receptors also inhibited cytokine-induced TUNEL staining in pancreatic islet cells. S1P and/or dihydro-S1P also antagonized cytokine-induced increases in cytochrome c release from mitochondria and caspase-3 activity in INS-1 cells, which are indicative of cell apoptosis vs. necrosis. S1P failed to affect nitric oxide synthase activity after 48 h. Thus, the evidence suggests that S1P acting on S1P receptors coupled to G(q) mediates protective effects on islet beta-cells against cytokine-induced apoptosis.