Antifungal efficacy of natural antiseptic products against Candida auris.

Candida auris is an emerging fungal pathogen responsible for healthcare-associated infections and outbreaks with high mortality around the world. It readily colonizes the skin, nares, respiratory and urinary tract of hospitalized patients, and such colonization may lead to invasive Candida infection in susceptible patients. However, there is no recommended decolonization protocol for C. auris by international health authorities. The aim of this study is to evaluate the susceptibility of C. auris to commonly used synthetic and natural antiseptic products using an in vitro, broth microdilution assay. Synthetic antiseptics including chlorhexidine, povidone-iodine, and nystatin were shown to be fungicidal against C. auris. Among the natural antiseptics tested, tea tree oil and manuka oil were both fungicidal against C. auris at concentrations less than or equal to 1.25% (v/v). Manuka honey inhibited C. auris at 25% (v/v) concentrations. Among the commercial products tested, manuka body wash and mouthwash were fungicidal against C. auris at concentrations less than or equal to 0.39% (w/v) and 6.25% (v/v) of products as supplied for use, respectively, while tea tree body wash and MedihoneyTM wound gel demonstrated fungistatic properties. In conclusion, this study demonstrated good in vitro antifungal efficacy of tea tree oil, manuka oil, manuka honey, and commercially available antiseptic products containing these active ingredients. Future studies are warranted to evaluate the effectiveness of these antiseptic products in clinical settings.

Candida auris is an emerging superbug fungus that poses a serious threat to global public health. The excellent antifungal efficacy of natural antiseptics and their commercial hygiene products provide new insights into the development of an alternative decolonization regimen against C. auris.

Stroke caregivers' perception on instant messaging application use for psychological intervention: a qualitative study.

In caring for patients with stroke, the leading cause of death and disability affecting over 80 million people worldwide, caregivers experience substantial psychological and physical burdens and difficulties in help-seeking owing to physical and time-constraints. Social distancing measures imposed during the coronavirus disease 2019 (COVID-19) pandemic further restricted them from using caregiver support services. While the use of telehealth emerged as a global prevailing trend during the COVID-19 pandemic, evidence for utilising instant messaging (IM) applications for psychological intervention is scanty. This study aimed to explore stroke caregivers' perceived potential utility of IM-delivered psychological intervention. Between January and August 2020, 36 adult family stroke caregivers in Hong Kong were recruited to individual telephone semi-structured interviews using purposive sampling. The interviews were audio-recorded, transcribed verbatim and analysed using an interpretive description approach. Three themes of caregivers' perceptions towards IM-delivered psychological intervention emerged: perceived high convenience and ease of use, perceived advantages that overcome existing barriers to services and message delivery tailored to individual needs. Our findings suggested that there is an imminent need among stroke caregivers for personalised psychological interventions and that IM is a potential modality for overcoming existing barriers in delivering accessible support to caregivers in real-time, real-world settings. Our study highlighted caregivers' acceptance and perceived benefits of IM-delivered psychological intervention and provided practical insights into the design of IM-delivered psychological interventions.

Qualitative Study of Chinese Stroke Caregivers' Caregiving Experience During the COVID-19 Pandemic.

BACKGROUND AND PURPOSE: The coronavirus disease 2019 (COVID-19) outbreak has led to disruptions in health care service delivery worldwide, inevitably affecting stroke survivors requiring ongoing rehabilitation and chronic illness management. To date, no published research has been found on stroke caregiving during the COVID-19 pandemic. This study aimed to explore Hong Kong stroke caregivers' caregiving experiences in the midst of this difficult time. METHODS: Individual semistructured interviews were conducted with 25 Chinese adult primary stroke caregivers from May to June 2020 via telephone. Interviews were transcribed verbatim and analyzed using an interpretive description approach and constant comparison strategy. RESULTS: Five themes of the stroke caregiving experience during the COVID-19 pandemic emerged: care service adversities, additional caregiving workload and strain, threatened relationship between caregiver and stroke survivors, threats to caregivers' physical and psychological well-being, and needs for continuing caregiving roles. Our findings suggested that caregivers have worsened physical and psychological well-being because of increases in care burden with simultaneously reduced formal and informal support. The relationship between caregiver and stroke survivor was subsequently affected, placing some survivors at heightened risk of abuse. CONCLUSIONS: Our study provides valuable findings about stroke caregiving experiences and needs during the pandemic. Delivery of psychological support, telemedicine, and household hygiene resources would be useful to mitigate caregivers' psychological distress during the COVID-19 pandemic.

Unimolecular Rate Expression for Cyclohexene Decomposition and Its Use in Chemical Thermometry under Shock Tube Conditions.

The methods used in deriving the rate expressions from comparative rate single-pulse shock tube studies, recent direct shock tube studies, and high-pressure flow experiments bearing on the data for the reverse Diels-Alder decomposition of cyclohexene to form ethylene and 1,3-butadiene are reviewed. This current interest is due to the increasing need for accurate kinetics and physical data (particularly the temperature) for realistic simulations in practical areas such as combustion. The rate constants derived from the direct shock tube studies and high-pressure flow experiments are somewhat larger than those used in comparative rate single-pulse shock tube experiments. For the latter, it is shown that they have been derived from a variety of independent experiments that include rate constants for unimolecular decomposition and isomerization processes that are considered to be well understood. The possibility of non-Arrhenius behavior in the unimolecular rate constants as a consequence of the large range covered in rate constants (as much as 12 orders of magnitude) for the comparative rate experiments has been examined and ruled out as a source of the discrepancy. Our analysis shows that there is the need to consider the possibility of radical-induced decompositions for verifying the correctness of the reaction mechanisms in studying unimolecular reactions. In the case of cyclohexene decomposition, recent experiments demonstrating the presence of residual amounts of H atoms in shock tube experiments suggest that addition to the double bond can also lead to the formation of ethylene and 1,3-butadiene and hence to rate constants larger than the true values. This possibility is even more likely to occur in high-pressure flow experiments. As a result, the internal standard method must be used with care and a radical inhibitor should always be present in sufficiently large quantities to suppress possible chain reactions. The present analysis results have important implications for the determination of temperatures in shock tubes.

Isomerization of cis-1,2-dimethylcyclohexane in single-pulse shock tube experiments.

Cyclic hydrocarbons are major constituents of jet fuels and reference compounds in jet fuel surrogates. The kinetic and thermal stability and reaction mechanisms of fuel molecules are essential input parameters in the models and simulations used in the design of novel fuels, renewable energy technologies, and devices. A detailed study and analysis of the pyrolytic chemistry of cis-1,2-dimethylcyclohexane has been performed in single-pulse shock tube experiments. The investigations are carried out over the temperature range of 1100 to 1200 K at about 2.5 atm pressure. The isomeric products are trans-1,2-dimethylcyclohexane, 1-octene, and (cis + trans)-2-octene. The three octene isomers can be attributed to internal disproportionation processes. Assuming a diradical mechanism and that cis-1,2-dimethylcyclohexane is formed in equal amount with respect to its trans isomer, the total rate expression for isomerization is kC-C = 10(15.5±0.8) exp(-38,644 ± 2061 K/T) s(-1). The rate constants are over an order of magnitude smaller than the equivalent noncyclic hydrocarbon system. The presence of the isomeric octenes suggests that internal disproportionation is an important component of the isomerization process.

Bond cleavage during isobutanol thermal decomposition and the breaking of C-C bonds in alcohols at high temperatures.

Isobutanol was thermally decomposed in a single pulse shock tube under conditions where chain processes were suppressed. The main reaction is the breaking of C-C bonds. Literature rate expressions, experimentally determined, are found in some cases to be in disagreement. The rate expressions for the decomposition processes at temperatures of 1090 to 1240 K and pressures of 1.5 and 6 atm are k(isobutanol → isopropyl + hydroxymethyl) + k(isobutanol → methyl + 1-hydroxypropyl-2) = 10(16.7±0.3) exp(-41097 ± 750) s(-1), where k(isobutanol → isopropyl + hydroxymethyl) = 10(16.45 ±0.3) exp(-40910 ± 750/T) s(-1) and k(isobutanol → methyl + 1-hydroxypropyl-2) = 10(16.38±0.3) exp(-41560 ± 750/T) s(-1). These values permit comparisons with recent estimates including those from ab initio calculations. A new procedure is presented that uses information on the kinetics of bond breaking reactions of alkanes and the effect of OH substitution to derive rate coefficients for similar reactions of alcohols. This leads to the following rate expression for the smaller alcohols, at temperatures of 1090 to 1240 K and pressures of 1.5 and 6 atm, k(ethanol → methyl + hydroxymethyl) = 10(16.42±0.3) exp(-43496 ± 750 K/T) s(-1), k(isopropanol → methyl + 1-hydroxyethyl) = 10(16.54±0.3) exp(-42495 ± 750 K/T) s(-1), k(n-propanol → ethyl + hydroxymethyl) = 10(16.43±0.3) exp(-41696 ± 750 K/T) s(-1), and k(n-propanol → methyl + 2-hydroxymethyl) = 10(16.53±0.3) exp(-42945 ± 750 K/T) s(-1). Extension of this approach to other alcohols is straightforward. The resulting correlations along with the data on dehydration of alcohols provide novel information of the kinetic stability of alcohols.

Dehydration of isobutanol and the elimination of water from fuel alcohols.

Rate coefficients for the dehydration of isobutanol have been determined experimentally from comparative rate single pulse shock tube measurements and calculated via multistructural transition state theory (MS-TST). They are represented by the Arrhenius expression, k(isobutanol → isobutene + H2O)(experimental) = 7.2 × 10(13) exp(-35300 K/T) s(-1). The theoretical work leads to the high pressure rate expression, k(isobutanol → isobutene + H2O)(theory) = 3.5 × 10(13) exp(-35400 K/T) s(-1). Results are thus within a factor of 2 of each other. The experimental results cover the temperature range 1090-1240 K and pressure range 1.5-6 atm, with no discernible pressure effects. Analysis of these results, in combination with earlier single pulse shock tube work, made it possible to derive the governing factors that control the rate coefficients for alcohol dehydration in general. Alcohol dehydration rate constants depend on the location of the hydroxyl group (primary, secondary, and tertiary) and the number of available H-atoms adjacent to the OH group for water elimination. The position of the H-atoms in the hydrocarbon backbone appears to be unimportant except for highly substituted molecules. From these correlations, we have derived k(isopropanol → propene + H2O) = 7.2 × 10(13) exp(-33000 K/T) s(-1). Comparison of experimental determination with theoretical calculations for this dehydration, and those for ethanol show deviations of the same magnitude as for isobutanol. Systematic differences between experiments and theoretical calculations are common.

Associations of eHealth literacy and knowledge with preventive behaviours and psychological distress during the COVID-19 pandemic: a population-based online survey.

OBJECTIVES: To compare the associations of COVID-19 preventive behaviours and depressive and anxiety symptoms with eHealth literacy and COVID-19 knowledge among Korean adults. DESIGN: A cross-sectional online survey was conducted in April 2020. SETTING: Seoul metropolitan area in South Korea. PARTICIPANTS: 1057 Korean adults were recruited. MAIN OUTCOME MEASURES: Associations between eHealth literacy, COVID-19 knowledge, COVID-19 preventive behaviours and psychological distress were computed using Pearson's correlation and logistic regression analyses. eHealth literacy, COVID-19 knowledge, COVID-19 preventive behaviours and psychological distress were weighted by sex and age distribution of the general population in Seoul Metropolitan area. RESULTS: 68.40% (n=723) perceived high eHealth literacy level (eHEALS ≥26), while 57.43% (n=605) had high levels of COVID-19 knowledge (score ≥25). No significant association between eHealth literacy and COVID-19 knowledge was identified (r=0.05, p=0.09). eHealth literacy and COVID-19 knowledge were significantly associated with COVID-19 preventive behaviours (aOR=1.99, 95% CI 1.51 to 2.62 L; aOR=1.81, 95% CI 1.40 to 2.34, respectively). High eHealth literacy was significantly associated with anxiety symptom (aOR=1.71, 95% CI 1.18 to 2.47) and depressive symptom (aOR=1.69, 95% CI 1.24 to 2.30). COVID-19 knowledge had negative and no associations with the symptoms (aOR=0.62, 95% CI 0.46 to 0.86; aOR=0.79, 95% CI 0.60 to 1.03, respectively). High eHealth literacy with low COVID-19 knowledge was positively and significantly associated with COVID-19 preventive behaviours (aOR=2.30, 95% CI 1.52 to 3.43), and anxiety (aOR=1.81, 95% CI 1.09 to 3.01) and depressive symptoms (aOR=2.24, 95% CI 1.41 to 3.55). High eHealth literacy with high COVID-19 knowledge were significantly associated with more preventive behaviours (aOR=3.66, 95% CI 2.47 to 5.42) but no significant associations with anxiety and depressive symptoms. CONCLUSION: We identified that eHealth literacy and COVID-19 knowledge were not associated each other, and differently associated with individuals' COVID-19 preventive behaviours and psychological well-being. Public health strategies should pay attention to enhancing both eHealth literacy and COVID-19 knowledge levels in the public to maximise their COVID-19 preventive behaviours and mitigate their psychological distress during COVID-19 pandemic.

Proton transfer from C-6 of uridine 5'-monophosphate catalyzed by orotidine 5'-monophosphate decarboxylase: formation and stability of a vinyl carbanion intermediate and the effect of a 5-fluoro substituent.

The exchange for deuterium of the C-6 protons of uridine 5'-monophosphate (UMP) and 5-fluorouridine 5'-monophosphate (F-UMP) catalyzed by yeast orotidine 5'-monophosphate decarboxylase (ScOMPDC) at pD 6.5-9.3 and 25 °C was monitored by (1)H NMR spectroscopy. Deuterium exchange proceeds by proton transfer from C-6 of the bound nucleotide to the deprotonated side chain of Lys-93 to give the enzyme-bound vinyl carbanion. The pD-rate profiles for k(cat) give turnover numbers for deuterium exchange into enzyme-bound UMP and F-UMP of 1.2 × 10(-5) and 0.041 s(-1), respectively, so that the 5-fluoro substituent results in a 3400-fold increase in the first-order rate constant for deuterium exchange. The binding of UMP and F-UMP to ScOMPDC results in 0.5 and 1.4 unit decreases, respectively, in the pK(a) of the side chain of the catalytic base Lys-93, showing that these nucleotides bind preferentially to the deprotonated enzyme. We also report the first carbon acid pK(a) values for proton transfer from C-6 of uridine (pK(CH) = 28.8) and 5-fluorouridine (pK(CH) = 25.1) in aqueous solution. The stabilizing effects of the 5-fluoro substituent on C-6 carbanion formation in solution (5 kcal/mol) and at ScOMPDC (6 kcal/mol) are similar. The binding of UMP and F-UMP to ScOMPDC results in a greater than 5 × 10(9)-fold increase in the equilibrium constant for proton transfer from C-6, so that ScOMPDC stabilizes the bound vinyl carbanions, relative to the bound nucleotides, by at least 13 kcal/mol. The pD-rate profile for k(cat)/K(m) for deuterium exchange into F-UMP gives the intrinsic second-order rate constant for exchange catalyzed by the deprotonated enzyme as 2300 M(-1) s(-1). This was used to calculate a total rate acceleration for ScOMPDC-catalyzed deuterium exchange of 3 × 10(10) M(-1), which corresponds to a transition-state stabilization for deuterium exchange of 14 kcal/mol. We conclude that a large portion of the total transition-state stabilization for the decarboxylation of orotidine 5'-monophosphate can be accounted for by stabilization of the enzyme-bound vinyl carbanion intermediate of the stepwise reaction.

Shock tube study on the thermal decomposition of n-butanol.

Dilute concentrations of normal-butanol has been decomposed in single pulse shock tube studies in the presence of large quantities of a chemical inhibitor that suppresses contributions from chain decomposition. Reaction temperatures and pressures are in the range of [1126-1231] K and [1.3-6.5] bar. Ethylene and 1-butene are the only products. The mechanism of the initial decomposition steps involves direct elimination of water and C-C bond cleavage. The fundamental high pressure unimolecular decomposition rate expressions are k(C(4)H(9)OH → CH(3) + CH(2)CH(2)CH(2)OH) = 10(16.4±0.4) exp(42410 ± 800 [K]/T) s(-1); k(C(4)H(9)OH → CH(3)CH(2) + CH(2)CH(2)OH) = 10(16.4±0.4) exp(-41150 ± 800 [K]/T) s(-1); k(C(4)H(9)OH → CH(3)CH(2)CH(2) + CH(2)OH) = 10(16.4±0.4) exp(-41150 ± 800 [K]/T) s(-1); and k(C(4)H(9)OH → CH(3)CH(2)CH═CH(2) + H(2)O) = 10(14.0±0.4) exp(-35089 ± 800 [K]/T) s(-1), where the rate expressions for C-C bond cleavage are based on assumptions regarding the relative rates of the three processes derived from earlier studies on the effect of an OH group on rate expressions. All reactions are in the high pressure limit and suggest that the step size down in the presence of argon is at least 1300 cm(-1). These rate expressions are consistent with the following H-C bond dissociation energies: BDE(H-CH(2)CH(2)CH(2)OH) = 417.2 ± 7 kJ/mol, BDE(H-CH(2)CH(2)OH) = 419.2 ± 7 kJ/mol, and BDE(H-CH(2)OH) = 401.7 ± 9 kJ/mol, with an estimated uncertainty of 6 kJ/mol. The kinetics and thermodynamic results are compared with estimates used in the building of combustion kinetics databases.

Shock tube studies on the decomposition of 2-butanol.

The thermal decomposition of 2-butanol have been studied at temperatures of 1045-1221 K and pressures of 1.5-6 bar using the single pulse shock tube technique. Dilute concentrations of 2-butanol have been decomposed in the presence of large quantities of a radical inhibitor. The mechanism for decomposition involves direct elimination of water producing cis- and trans-2-butene, and 1-butene, and C-C bond fission producing ethylene. Acetaldehyde, propionaldehyde, and propene were also observed in much smaller yields from C-C bond fission. The respective unimolecular rate expressions are as follows: k(C(3)H(6)(OH)CH(3) → cis-CH(3)CH═CHCH(3) + H(2)O) = 10(13.1 ± 0.3) exp(-33414 ± 755 K/T) s(-1); k(C(3)H(6)(OH)CH(3) → trans-CH(3)CH═CHCH(3) + H(2)O) = 10(13.5 ± 0.3) exp(-33820 ± 755 K/T) s(-1); k(C(3)H(6)(OH)CH(3) → CH(3)CH(2)CH═CH(2) + H(2)O) = 10(13.6 ± 0.3) exp(-33002 ± 755 K/T) s(-1); k(C(3)H(6)(OH)CH(3) → C(2)H(5)(•) + (•)CH(OH)CH(3)) = 10(15.9 ± 0.3) exp(-39252 ± 755 K/T) s(-1). These rate expressions are compared with analogous reactions for primary and tertiary butanols. They form a basis for the prediction of those for related systems. Comparison with estimated values used in the simulation of butanol combustion is indicative of the uncertainties in the rate constants that are used in such models. The activation energy of 326 kJ/mol leads to a bond dissociation energy of the CH(OH)CH(3) radical (H-CH(OH)CH(3)) of 400 kJ/mol, in excellent agreement with earlier calculated results from theory and disagreement with the experimental results from iodination studies in the expected range.

Tunneling in hydrogen-transfer isomerization of n-alkyl radicals.

The role of quantum tunneling in hydrogen shift in linear heptyl radicals is explored using multidimensional, small-curvature tunneling method for the transmission coefficients and a potential energy surface computed at the CBS-QB3 level of theory. Several one-dimensional approximations (Wigner, Skodje and Truhlar, and Eckart methods) were compared to the multidimensional results. The Eckart method was found to be sufficiently accurate in comparison to the small-curvature tunneling results for a wide range of temperature, but this agreement is in fact fortuitous and caused by error cancellations. High-pressure limit rate constants were calculated using the transition state theory with treatment of hindered rotations and Eckart transmission coefficients for all hydrogen-transfer isomerizations in n-pentyl to n-octyl radicals. Rate constants are found in good agreement with experimental kinetic data available for n-pentyl and n-hexyl radicals. In the case of n-heptyl and n-octyl, our calculated rates agree well with limited experimentally derived data. Several conclusions made in the experimental studies of Tsang et al. (Tsang, W.; McGivern, W. S.; Manion, J. A. Proc. Combust. Inst. 2009, 32, 131-138) are confirmed theoretically: older low-temperature experimental data, characterized by small pre-exponential factors and activation energies, can be reconciled with high-temperature data by taking into account tunneling; at low temperatures, transmission coefficients are substantially larger for H-atom transfers through a five-membered ring transition state than those with six-membered rings; channels with transition ring structures involving greater than 8 atoms can be neglected because of entropic effects that inhibit such transitions. The set of computational kinetic rates were used to derive a general rate rule that explicitly accounts for tunneling. The rate rule is shown to reproduce closely the theoretical rate constants.

Repeatability and reproducibility of ultrasonographic measurement of carotid intima thickness.

PURPOSE: To evaluate the repeatability and reproducibility of intima thickness (IT) measurements at different sites along the common carotid artery and compare with intima-media thickness (IMT) measurements. METHODS: Ultrasound examinations of common carotid artery were performed in 30 healthy subjects and 20 patients with diabetes mellitus. Carotid IT and IMT were measured at 10 mm, 13 mm, and 16 mm upstream from the carotid bulb. Each subject was scanned by three operators to evaluate inter-operator reproducibility. Each operator scanned the subjects twice to evaluate intra-operator repeatability. Inter-equipment reproducibility of the measurements was evaluated. RESULTS: The inter-operator reproducibility for measuring carotid IT at the three sites was 81.5%, 81.9% and 69.1%, respectively, slightly lower than carotid IMT measurement (89.7%, 86.5%, 75.2%, respectively). The intra-operator repeatability for carotid IT measurement at the three sites ranged 76.9-89.5%, 67.4-90.3%, and 55.2-70.5%, respectively, and was lower than for IMT measurement (86.5-96.9%, 87.6-95.7%, 79.9-86.5%, respectively). The inter-equipment reproducibility of IMT (75.7-86.6%) was slightly better than for IT measurement (71.4-75.9%). CONCLUSIONS: Ultrasonographic measurement of carotid IT is repeatable and reproducible, although not as good as IMT. Measurements preformed 10 mm to 13 mm upstream from the carotid bulb yield more repeatable and reproducible results.

Asymmetric hydroalkynylation of norbornadienes promoted by chiral iridium catalysts.

Across bonds: The first successful iridium-catalyzed asymmetric hydroalkynylation of nonpolar alkenes with good to excellent enantioselectivity is described (see scheme; cod = 1,5-cyclooctadiene, DCE = 1,2-dichloroethane). This catalytic system exhibits good functional group compatibility as NH(2), OH, Br, F, and SiMe(3) groups remain intact during the reaction.

H atom attack on propene.

The reaction of propene (CH(3)CH═CH(2)) with hydrogen atoms has been investigated in a heated single-pulsed shock tube at temperatures between 902 and 1200 K and pressures of 1.5-3.4 bar. Stable products from H atom addition and H abstraction have been identified and quantified by gas chromatography/flame ionization/mass spectrometry. The reaction for the H addition channel involving methyl displacement from propene has been determined relative to methyl displacement from 1,3,5-trimethylbenzene (135TMB), leading to a reaction rate, k(H + propene) → H(2)C═CH(2) + CH(3)) = 4.8 × 10(13) exp(-2081/T) cm(3)/(mol s). The rate constant for the abstraction of the allylic hydrogen atom is determined to be k(H + propene → CH(2)CH═CH(2) + H(2)) = 6.4 × 10(13) exp(-4168/T) cm(3)/(mol s). The reaction of H + propene has also been directly studied relative to the reaction of H + propyne, and the relationship is found to be log[k(H + propyne → acetylene + CH(3))/k(H + propene → ethylene + CH(3))] = (-0.461 ± 0.041)(1000/T) + (0.44 ± 0.04). The results showed that the rate constant for the methyl displacement reaction with propene is a factor of 1.05 ± 0.1 larger than that for propyne near 1000 K. The present results are compared with relevant earlier data on related compounds.

Oncofetal H19-derived miR-675 regulates tumor suppressor RB in human colorectal cancer.

H19 is an imprinted oncofetal non-coding RNA recently shown to be the precursor of miR-675. The pathophysiological roles of H19 and its mature product miR-675 to carcinogenesis have, however, not been defined. By quantitative reverse transcription-polymerase chain reaction, both H19 and miR-675 were found to be upregulated in human colon cancer cell lines and primary human colorectal cancer (CRC) tissues compared with adjacent non-cancerous tissues. Subsequently, the tumor suppressor retinoblastoma (RB) was confirmed to be a direct target of miR-675 as the microRNA suppressed the activity of the luciferase reporter carrying the 3'-untranslated region of RB messenger RNA that contains the miR-675-binding site. Suppression of miR-675 by transfection with anti-miR-675 increased RB expression and at the same time, decreased cell growth and soft agar colony formation in human colon cancer cells. Reciprocally, enhanced miR-675 expression by transfection with miR-675 precursor decreased RB expression, increased tumor cell growth and soft agar colony formation. Moreover, the inverse relationship between the expressions of RB and H19/miR-675 was also revealed in human CRC tissues and colon cancer cell lines. Our findings demonstrate that H19-derived miR-675, through downregulation of its target RB, regulates the CRC development and thus may serve as a potential target for CRC therapy.

On the question of stepwise vs. concerted cleavage of RNA models promoted by a synthetic dinuclear Zn(II) complex in methanol: implementation of a noncleavable phosphonate probe.

To address the question of concerted versus a stepwise reaction mechanisms for the cyclization of the 2-hydroxypropyl aryl and alkyl RNA models (1a-k) promoted by dinuclear Zn(II) complex (4) at (s)spH 9.8 and 25 degrees C, the non-cleavable O-hydroxypropyl phenylphosphonate analogues 6a and 6b were subjected to the catalytic reaction in methanol. These phosphonates did not undergo isomerization in the study, the only observable methanolysis reaction being release of 1,2-propanediol and the formation of O-methyl phenylphosphonate. The observed first order rate constants for methanolysis promoted by 4 are k(obs)(6a) = (1.47 +/- 0.09) x 10(-4) s(-1) and k(obs)(6b) = (2.08 +/- 0.09) x 10(-6) s(-1), respectively. The rates of methanolysis of a series of O-aryl phenylphosphonates (8a-f) in the presence of increasing [4] were analyzed to provide binding constants, Kb, and the catalytic rate constant, kcat(max), for the unimolecular decomposition of the 8:4 Michaelis complex. A Brønsted plot of the log (k(cat)(max)) vs. sspKa(phenol) (acidity constant of the conjugate acid of the leaving group in methanol) was fitted to a linear regression of log kcat(max) = (-0.80 +/- 0.07)(s)spKa + (10.2 +/- 1.0) which includes the datum for 6a. The datum for 6b, which reacts approximately 70-fold slower, falls significantly below the linear correlation. The data provide additional evidence consistent with a concerted cyclization of RNA models 1a-k promoted by 4.

Kinetics of the thermal reaction of H atoms with propyne.

The reaction of hydrogen atoms with propyne (CH[triple bond]CCH(3)) was investigated in a heated single pulse-shock tube at temperatures of 874-1196 K and pressures of 1.6-7.6 bar. Stable products from various reaction channels (terminal and nonterminal H addition, and by inference H abstraction) were identified and quantified by gas chromatography and mass spectrometry. The rate constant for the channel involving the displacement of methyl radical from propyne (nonterminal H addition) was determined relative to the methyl displacement from 1,3,5-trimethylbenzene (135-TMB), with k (H + 135-TMB --> m-xylene + CH(3)) = 6.70 x 10(13) exp(-3255/T[K]) cm(3)/mol x s, k(H+propyne-->CH[triple bond]CH+CH3))=6.26 x 10(13) exp(-2267/T[K]) cm3/mole x s. Our results show that the acetylene to allene yield is approximately 2 at 900 K, and decreases with increasing temperature. The rate expression is: k(H+propyne-->CH2=C=CH2+H))=2.07 x 10(14) exp(-3759/T[K]) cm3/mole x s. This is a lower limit for terminal addition. Kinetic information for abstraction of the propargylic hydrogen by H was determined via mass balance. The rate expression is approximately k(H+CH3C[triple bond]CH-->CH[triple bond]C-CH2+H2))=1.20 x 10(14) exp(-4940/T[K])cm3 /mole x s and is only 10% of the rate constant for acetylene formation. All channels from H atom attack on propyne at combustion temperatures have now been determined. Comparisons are made with results of recent ab initio calculations and conclusions are drawn on the quantitative accuracy of such estimates.

Decomposition and isomerization of 5-methylhex-1-yl radical.

The decomposition and isomerization reactions of the 5-methylhex-1-yl radical (1-5MeH) have been studied at temperatures of 889-1064 K and pressures of 1.6-2.2 bar using the single pulse shock tube technique. The radical of interest was generated by shock heating dilute mixtures of 5-methylhexyl iodide to break the weak C-I bond, and the kinetics and reaction mechanism deduced on the basis of the olefin cracking pattern observed by gas chromatographic analysis of the products. In order of decreasing molar yields, alkene products from 1-5MeH decomposition are ethene, isobutene, propene, 3-methylbut-1-ene, but-1-ene, E/Z-hex-2-ene, 4-methylpent-1-ene, and hex-1-ene. The first three products account for almost 90% of the carbon balance. The mechanism involves reversible intramolecular H-transfer reactions that lead to the formation of the radicals 5-methylhex-5-yl (5-5MeH), 5-methylhex-2-yl (2-5MeH), 5-methylhex-4-yl (4-5MeH), 5-methylhex-6-yl (6-5MeH), and 5-methylhex-3-yl (3-5MeH). Competitive with isomerization reactions are decompositions by beta C-C bond scission. The main product forming radical is 5-5MeH, which is formed by intramolecular abstraction of the lone tertiary H in the radical. This reaction is deduced to be a factor of 4.0 +/- 0.7 faster on a per hydrogen basis than the analogous abstraction of a secondary hydrogen in 1-hexyl radical. The estimated uncertainty corresponds to 1 standard deviation. The following relative rates have been deduced under our reaction conditions: k(4-5MeH --> C(2)H(5) + 3-methylbut-1-ene)/k(4-5MeH --> CH(3) + Z-hex-2-ene) = 10((0.39+/-0.12)) exp[(675 +/- 270)K/T]; k(4-5MeH --> C(2)H(5) + 3-methylbut-1-ene)/k(4-5MeH --> CH(3) + E-hex-2-ene) = 10((-0.10+/-0.09)) exp[(1125 +/- 210)K/T]; k(3-5MeH --> iso-C(3)H(7) + but-1-ene)/(k)(3-5MeH --> CH(3) + 4-methylpent-1-ene) = 10((0.26+/-0.55)) exp[(1720 +/- 1300)K/T]. Observed olefin distributions depend on the relative rate constants and the interplay of chemical activation and falloff behavior as the energy distributions of the various radicals relax to steady-state values. A kinetic model using an RRKM/master equation analysis has been developed, and absolute rate expressions have been deduced. The model was used to extrapolate the data to temperatures between 500 and 1900 K and pressures of 0.1-1000 bar, and results for 12 isomerization reactions and 10 beta C-C bond scission reactions are reported.

Mycophenolate sodium in the treatment of corticosteroid-refractory non-infectious inflammatory uveitis (MySTRI study).

OBJECTIVES: To evaluate the therapeutic effect and safety profile of next generation mycophenolate sodium (MPS), which is different from mycophenolate mofetil with an enteric-coated formulation, in corticosteroid-refractory non-infectious inflammatory uveitis (CRU) patients. METHODS: Prospective, uncontrolled, open-label interventional case series. Forty consecutive patients at a tertiary uveitis referral centre received 6 months of oral MPS as the treatment regimen with follow-up 12 months. The main outcome measures were best-corrected visual acuity (BCVA), inflammatory index, steroid-sparing effect of tapering prednisone to ≤10 mg daily and side effects. RESULTS: Mean age of enroled patients was 49 (49 ± 13) years and 29 (72.5%) were female. Thirty-six (90.0%) had bilateral disease. There were 0 (0%) anterior uveitis, 2 (5.0%) intermediate uveitis, 22 (55.0%) posterior uveitis, and 16 (40.0%) panuveitis. Vogt-Koyanagi-Harada disease was the most common diagnosis (17/40, 42.5%), followed by idiopathic panuveitis (8/40, 20%) and idiopathic retinal vasculitis (5/40, 12.5%). LogMAR BCVA improved from 0.9 (SD = 0.09) to 0.31 (SD = 0.08) after 6 months of MPS with good steroid-sparing effect (p = 0.012). Further maintenance in LogMAR BCVA was evident after MPS discontinuation from 6th month to 12th month, from 0.31 (SD = 0.08) to 0.33 (SD = 0.07), respectively (p = 0.81). MPS was the only immunosuppressive drug needed to reach quiescent state in 29 patients (72.5%). The drug-related safety profile was satisfactory. CONCLUSION: MPS is an effective steroid-sparing drug for the treatment of CRU. The effect seen was not only during the 6 months of therapy, but also extended to 12 months to maintain BCVA and inflammation control. The side effects were acceptable.