Photodynamic antimicrobial chemotherapy activities of phthalocyanine-antibiotic conjugates against bacterial biofilms and interactions with extracellular polymeric substances

This study sheds light on how to rationally design efficient photodynamic antimicrobial chemotherapy (PACT) agents by covalently linking phthalocyanines (Pcs) as photosensitizers with an antibiotic: Ciprofloxacin (CIP). Pcs used are zinc (II) 3-(4-((3,17,23-tris(4-(Benzo(d)thiazol-2-yl] thiol) phthalocyanine-9-yl) oxy) phenyl) propanoic acid (1) and zinc (II) 3-(4-(3,17,23-tris(3-(4-(triphenylphosphine) butyl) benzo[d]thiazol-3-ium bromide phthalocyanine-9-yl) oxy) phenyl) propanoic acid (2). High singlet oxygen quantum yields are observed in the presence of CIP. Square wave voltammetry was used to analyse the Pc-CIP uptake by bacteria biofilms of Streptococcus pneumoniae (S. pneumonia) and Escherichia coli (E. coli). Electrochemical impedance spectroscopy and scanning electron spectroscopy were used to study the stability of the biofilms in the presence Pc-CIP complexes and when exposed to light. Raman and time of flight-secondary ion mass spectrometry (TOF-SIMS) are used to identify the breakdown of cellular components of the biofilm and penetration of the Pc-CIP into the biofilms, respectively.

The development of folate-functionalised palladium nanoparticles for folate receptor targeting in breast cancer cells

Folate receptor-targeted therapy has excellent prospects for the treatment of breast cancer. A non-toxic concentration of folate-conjugated palladium-based nanoparticles was used to target the overexpressed folate receptor on breast cancer cells. The folate-conjugated nanoparticles were tailored to accumulate selectively in cancer cells relative to normal cells via the folate receptor. The MDA-MB-231, MDA-MB-468, MCF-7 breast cancer cell lines, and MCF-10A normal cell lines were used in the study. Qualitative and quantitative analysis of nanoparticle cellular uptake and accumulation was conducted using transmission electron microscopy and inductively coupled plasma-optical emission spectroscopy. The findings proved that folate-conjugated palladium nanoparticles successfully and preferentially accumulated in breast cancer cells. We conclude that folate-conjugated palladium nanoparticles can be potentially used to target breast cancer cells for radiopharmaceutical applications.

Safety and efficacy of tenecteplase in patients with wake-up stroke assessed by non-contrast CT (TWIST): a multicentre, open-label, randomised controlled trial

BACKGROUND

Current evidence supports the use of intravenous thrombolysis with alteplase in patients with wake-up stroke selected with MRI or perfusion imaging and is recommended in clinical guidelines. However, access to advanced imaging techniques is often scarce. We aimed to determine whether thrombolytic treatment with intravenous tenecteplase given within 4·5 h of awakening improves functional outcome in patients with ischaemic wake-up stroke selected using non-contrast CT.

METHODS

TWIST was an investigator-initiated, multicentre, open-label, randomised controlled trial with blinded endpoint assessment, conducted at 77 hospitals in ten countries. We included patients aged 18 years or older with acute ischaemic stroke symptoms upon awakening, limb weakness, a National Institutes of Health Stroke Scale (NIHSS) score of 3 or higher or aphasia, a non-contrast CT examination of the head, and the ability to receive tenecteplase within 4·5 h of awakening. Patients were randomly assigned (1:1) to either a single intravenous bolus of tenecteplase 0·25 mg per kg of bodyweight (maximum 25 mg) or control (no thrombolysis) using a central, web-based, computer-generated randomisation schedule. Trained research personnel, who conducted telephone interviews at 90 days (follow-up), were masked to treatment allocation. Clinical assessments were performed on day 1 (at baseline) and day 7 of hospital admission (or at discharge, whichever occurred first). The primary outcome was functional outcome assessed by the modified Rankin Scale (mRS) at 90 days and analysed using ordinal logistic regression in the intention-to-treat population. This trial is registered with EudraCT (2014-000096-80), ClinicalTrials.gov (NCT03181360), and ISRCTN (10601890).

FINDINGS

From June 12, 2017, to Sept 30, 2021, 578 of the required 600 patients were enrolled (288 randomly assigned to the tenecteplase group and 290 to the control group [intention-to-treat population]). The median age of participants was 73·7 years (IQR 65·9-81·1). 332 (57%) of 578 participants were male and 246 (43%) were female. Treatment with tenecteplase was not associated with better functional outcome, according to mRS score at 90 days (adjusted OR 1·18, 95% CI 0·88-1·58; p=0·27). Mortality at 90 days did not significantly differ between treatment groups (28 [10%] patients in the tenecteplase group and 23 [8%] in the control group; adjusted HR 1·29, 95% CI 0·74-2·26; p=0·37). Symptomatic intracranial haemorrhage occurred in six (2%) patients in the tenecteplase group versus three (1%) in the control group (adjusted OR 2·17, 95% CI 0·53-8·87; p=0·28), whereas any intracranial haemorrhage occurred in 33 (11%) versus 30 (10%) patients (adjusted OR 1·14, 0·67-1·94; p=0·64).

INTERPRETATION

In patients with wake-up stroke selected with non-contrast CT, treatment with tenecteplase was not associated with better functional outcome at 90 days. The number of symptomatic haemorrhages and any intracranial haemorrhages in both treatment groups was similar to findings from previous trials of wake-up stroke patients selected using advanced imaging. Current evidence does not support treatment with tenecteplase in patients selected with non-contrast CT.

FUNDING

Norwegian Clinical Research Therapy in the Specialist Health Services Programme, the Swiss Heart Foundation, the British Heart Foundation, and the Norwegian National Association for Public Health.

Effect of ultrasonic frequency and power on the sonodynamic therapy activity of cationic Zn(II) phthalocyanines

We report on the sonodynamic activity of cationic phthalocyanines (Pcs) and the effect of the variation of two parameters: ultrasound frequency and power (Par I (1 MHz, 1 W cm^-2), Par II (1 MHz, 2 W cm^-2), Par III (3 MHz, 1 W cm^-2) and Par IV (3 MHz, 2 W cm^-2)) on the efficiency of their reactive oxygen species generation and cancer eradication in vitro thereof. Where Par stands for the various combinations of these parameters. Four Pcs were investigated with substituents bearing diethylamine, ortho- and para-pyridine and morpholine groups. Overall, the para-pyridine and morpholine Pcs showed substantial sono-activity in the various ultrasound parameters with Par I and IV generally showing better singlet oxygen and hydroxyl radicals generation confirmed by electron paramagnetic resonance spectroscopy. In some cases, very high hydroxyl radicals' generation was observed at Par II. Furthermore, the fragmentation of the Pcs after Par II treatments was confirmed using UV-vis and magnetic circular dichroism spectroscopy. The reactive species generation efficacy decreased at Par III for all samples. Ultrasound assisted cytotoxicity of the Pcs was confirmed in vitro using the human (Michigan Cancer Foundation-7) breast cancer cell line.

The improved antibacterial efficiency of a zinc phthalocyanine when embedded on silver nanoparticle modified silica nanofibers

This work reports on the fabrication and modification of electrospun polymer free silica nanofibers (SiO₂ NFs) with the aim of creating heterogeneous antibacterial catalysts. The optical and photophysical properties of the obtained NFs i.e. bare SiO₂, Ag-SiO₂, Pc-SiO₂ and Pc@Ag-SiO₂ NFs (Pc = phthalocyanine) were compared and reported. The singlet oxygen quantum yields of the Pc-SiO₂ and Pc@Ag-SiO₂ NFs were also quantified and found to be 0.08 and 0.12, respectively, in water. All the modified SiO₂ NFs were found to possess photoactivity against S. aureus with the most effective being the Pc@Ag-SiO₂ NFs due to the synergy between the Pc and Ag nanoparticles. The bare SiO₂ NFs do not exhibit any antibacterial activity while the Ag-SiO₂ and Pc@Ag-SiO₂ NFs were found to also exhibit dark toxicity. The generated photocatalysts are attractive because they are active against bacteria and they are easily retrievable post-application. The nanocatalysts reported herein are therefore feasible candidates for real-life antibacterial applications.

Growth of centimeter scale carbon wires using in-liquid AC arc discharge

A novel observation of the formation of carbon wire in a carbon-based liquid solvent, using in liquid high voltage AC arc discharge is described. The authors describe the observed phenomenon, technical equipment needed to achieve the effect and preliminary qualitative results of obtained material. The wire consisted of well packed layers of carbon elements. The arc-discharge method is a simple, low cost method for the production of three dimensional carbon structures. A further research is needed to get a thorough understanding of the phenomenon.

Repeatability of High Resolution Laser Doppler Images of the hands in patients with systemic sclerosis and secondary Raynaud's phenomenon

OBJECTIVES

The objective of the study was to establish the repeatability of baseline diagnostic images of the dorsum of the hands acquired using a high resolution Laser Doppler imager in patients with Raynaud's phenomenon secondary to Systemic Sclerosis (SSc).

METHODS

The dorsal side of the hands of 22 patients (8 male 14 female) , age range 29-73, median 62, with SSc and secondary Raynaud's phenomenon were imaged over two consecutive days at approximately the same time using a Moor Instruments High Resolution Laser Doppler imaging unit. The images were analysed by taking regions of interest at discrete locations in the images to calculate dimensionless values of flux(PU). Repeatability of the diagnostic investigation was assessed by using methods described by Bland and Altman and by also plotting the results from visit 1 against visit 2 and calculating the line of best fit.

RESULTS AND CONCLUSIONS

Based on the criteria that 95% of all measurement differences should be within a factor of 1.96 of the standard deviations of the mean values, then high resolution Laser Doppler Imaging technique is probably repeatable when acquiring and analysing baseline images of patients with Raynaud's phenomenon secondary to SSc. However a larger study with more patients is required to prove this conclusively - as only data from 19 patients was analysed [3 patients were not included due to technical issues] - and was therefore susceptible to marked clinical variations in patients presenting on different days for the investigations.

Validity and sensitivity to change of laser Doppler imaging as a novel objective outcome measure for cutaneous lupus erythematosus

OBJECTIVES

The objectives of this study were to assess the reliability of a novel objective outcome measure, laser Doppler imaging (LDI), its validity against skin biopsy histology and other clinical instruments, including localized cutaneous lupus disease area and severity index (L-CLASI) and visual analogue scale (VAS) score of photographs, and its responsiveness to clinical change with therapy.

METHODS

A prospective observational cohort study was conducted in 30 patients with active cutaneous lupus erythematosus (CLE). At baseline and 3 months, disease activity was assessed using L-CLASI and a high resolution LDI system by two assessors. Skin biopsy was scored as 0 = non-active, 1 = mild activity and 2 = active. Photographs were assessed by two clinicians using 100 mm VAS. Inter-rater reliability was analyzed using Bland-Altman limits of agreement. Correlation between histology and LDI, L-CLASI and VAS and sensitivity to change of LDI with physician subjective assessment of change (PSAC) at 3 months were analyzed using Kendall's tau-a.

RESULTS

Of 30 patients with CLE, 28 (93%) were female, mean (SD) age 48.4 (11.5) y, 25 (83%) were Caucasians, 25 (83%) had concurrent systemic lupus erythematosus and 16 (53%) were smokers. CLE subtypes were acute = 9, subacute = 8 and chronic = 13. Inter-rater agreement for LDI was fair but for VAS score of photographs was poor. In 20 patients with biopsy, correlation with histology was better for LDI (tau-a = 0.53) than L-CLASI (tau-a = 0.26) (difference = 0.27; 90% CI 0.05-0.49) or VAS score of photographs (tau-a = 0.17) (difference = 0.36; 90% CI 0.04-0.68). There was a moderate correlation between PSAC score and change in LDI (tau-a = 0.56; 90% CI 0.38-0.74; p < 0.001, n = 15).

CONCLUSION

LDI provides a reliable, valid and responsive quantitative measure of inflammation in CLE. It has a better correlation with histology compared to clinical instruments. LDI provides an objective outcome measure for clinical trials.

Alcohol consumption and risk of tuberculosis: a systematic review and meta-analysis

OBJECTIVE

To perform a systematic review and meta-analysis of the association between alcohol consumption and risk of tuberculosis (TB).

METHODS

Medline, EMBASE and Web of Science were searched for observational studies from 2005 to April 2018. Reference lists of included studies were screened.

RESULTS

Forty-nine studies were included. Compared with people with low or no alcohol intake, the risk of TB in people with high or any alcohol consumption was increased by relative odds of 1.90 (95%CI 1.63-2.23). Substantial levels of heterogeneity were seen (I² = 82%); however, there was no evidence of publication bias (P = 0.54). Sensitivity analysis restricted to studies using no alcohol drinking as a reference group found a slightly lower but still increased risk (OR 1.60, 95%CI 1.39-1.84). Subgroup analyses revealed no significant differences in relation to study design and quality, geographic location, publication year or adjustment for confounders. A pooled analysis of a further four studies reporting hazard ratios (HRs) found a nearly three-fold increase in risk of TB in relation to alcohol consumption during follow-up (HR 2.81, 95%CI 2.12-3.74). An exposure-response analysis showed that for every 10-20 g daily alcohol intake, there was a 12% increase in TB risk.

CONCLUSION

Alcohol consumption is an important risk factor for the development of TB.

What is the association between price and economic activity with cigarette consumption in Cuba from 1980 to 2014?

OBJECTIVES

Cuba is a tobacco-producing country that has been economically isolated as a consequence of an embargo imposed by the USA. It has also experienced a severe economic depression in the 1990s after the withdrawal of support by the former Soviet Union. These characteristics provide a unique opportunity to study the relation between large changes in economic activity, cigarette price and demand for cigarettes in a relatively isolated socialist economy.

STUDY DESIGN

This is an observational epidemiological study.

METHODS

Data were obtained on the annual price of a packet of cigarettes and the mean number of cigarettes consumed per adult living in Cuba from 1980 to 2014. Descriptive and regression analysis were used to explore the relationship between cigarette consumption and price in Cuba.

RESULTS

In 1980, the mean price of a packet of cigarettes was 1.53 Cuban peso (CUP) in 1997 prices and the mean annual per capita consumption was 2237 cigarettes. In 2014, the mean price had increased to 5.57 CUP (1997 prices) per packet of cigarettes, and consumption had fallen to 1527 cigarettes per capita. There were significant negative associations between annual cigarette consumption and both price and living through an economic depression. The elasticity was approximately -0.31 with price, and living through an economic depression was also associated with lower consumption of cigarettes (a reduction of 9%, 95% confidence intervals -0.18 to -0.001).

CONCLUSIONS

Higher cigarette pricing, along with other public health interventions, are required to protect the national population from the adverse effects of tobacco smoke exposure.

Prevalence and risk factors for initiating tobacco and alcohol consumption in adolescents living in urban and rural Ethiopia

Objectives

African countries are potential high growth markets for the alcohol and tobacco industries. This study aimed to identify exposures that are associated with initiating use of alcohol and tobacco products in young people living in Ethiopia. As televised football and Internet viewing are media through which products can be promoted to this population efficiently, these risk factors were of particular interest.

Study design

This is a cross-sectional study.

Methods

Data were collected using a self-administered questionnaire of 3967 children aged 13–19 years in 20 high schools in urban and rural Ethiopia on consumption and risk factors for alcohol and tobacco use in 2016, as well as exposure to potential sources of advertising.

Results

Eight percent of respondents reported having ever smoked and 3% were current smokers. Twenty-nine percent reported ever having used alcohol, and 14% were current users. Risk factors for ever smoking included father smoking (odds ratio [OR] 1.95; 95% confidence interval [CI]: 1.21 to 3.15), mother smoking (OR 3.90; 95% CI: 1.63 to 9.33), best friend smoking (OR 5.86; 95% CI: 4.31 to 7.96) and home Internet access (OR 1.75; 95% CI: 1.35 to 2.27). There was a very strong positive association between ever having smoked cigarettes and ever having tried alcohol (P < 0.001). Risk factors for currently drinking alcohol included father drinking (OR 1.45; 95% CI: 1.05 to 2.01), mother drinking (OR 2.00; 95% CI: 1.44 to 2.77), home Internet access (OR 1.53; 95% CI: 1.24 to 1.90) and regular watching of televised football (OR 2.44 compared to those who do not; 95% CI: 1.58 to 3.78).

Conclusions

As in rich countries, tobacco and alcohol use among Ethiopian teenagers increases among those exposed to family and peer use but are also more common among those accessing the Internet and, for alcohol, those watching televised football. The effect of watching televised football on alcohol use, at least, is likely to be due to exposure to advertising.

•

Rapid economic development is changing the environment in developing countries rapidly, generating a new potential market for the alcohol and tobacco industries.

•

Fourteen percent of adolescents living in Ethiopia are regular consumers of alcohol, and 3% regularly smoke cigarettes.

•

Regular watching of international football on television is associated with being a current consumer of alcohol.

•

Public health strategies to modify alcohol and tobacco usage in adolescents living in Ethiopia need to consider that the Internet and televised football matches are potential sources of exposure to advertising aiming to promote consumption.

Photophysics and NLO properties of Ga(III) and In(III) phthalocyaninates bearing diethyleneglycol chains

This work reports on synthesis and characterizations of Ga(III) and In(III) complexes, formed by 2,3-bis[2[Formula: see text]-(2[Formula: see text]-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-[Formula: see text]-butoxy phthalocyanine (1H2) coordinating acetatoindium(III) (1InOAc) and hydroxogallium(III) (1GaOH) Photophysical properties of hydroxogallium(III) phthalocyaninate 1GaOH and acetatoindium(III) phthalocyaninate 1InOAc were studied by UV-vis, fluorescence spectroscopy and time-resolved methods. The nonlinear absorption of the complexes was studied using the Z-scan technique at 532 nm and 10 ns pulse in DMSO and in thin films formed by composite with poly(bisphenol A carbonate) — PBC. The magnitude of absorption coefficients and other nonlinear optical parameters estimated in this work showed that complex 1InOAc exhibited the strongest nonlinear optical behavior in comparison with 1GaOH in solution and a reverse tendency when embedded in PBC thin films. DFT calculations were used to rationalize these results.

Effect of Inhaled Alpha-Blocker on Airflow Obstruction in Asthma1

A controlled study of the effect on airflow obstruction of 30 mg of the alpha-blocker thymoxamine given by inhalation is reported in 10 patients with chronic stable asthma. No significant change in peak expiratory flow rate was seen with either thymoxamine or placebo in any patient. Alpha-adrenergic receptors are therefore unlikely to contribute significantly to resting bronchomotor tone in chronic stable asthma.

The effect of the cobalt and manganese central metal ions on the nonlinear optical properties of tetra(4-propargyloxyphenoxy)phthalocyanines

The phthalocyanines were investigated as optical limiters. The paramagnetic complexes were not effective owing to quenching of the excited states.

Solvent Effect on the Third-Order Nonlinear Optical Properties of α- and β-Tertbutyl Phenoxy-Substituted Tin(IV) Chloride Phthalocyanines

This paper investigates the third-order nonlinear optical properties of 4α-(4-tert-butylphenoxy) phthalocyaninato dichlorotin(IV) (α-SnOtBpPc) and 4β-(4-tert-butylphenoxy) phthalocyaninato dichlorotin(IV) (β-SnOtBpPc) in different organic solvents. The third-order susceptibilities of α-SnOtBpPc and β-SnOtBpPc are reported in different solvents, using Z-scan techniques with 10 ns laser pulses at 532 nm. Their nonlinear absorption coefficient and absorption cross sections were also determined. The molecular imaginary components of the second-order hyperpolarizability Im[γ] of α-SnOtBpPc and β-SnOtBpPc were found to be 2.60 × 10^-31 and 2.94 × 10^-31 esu (tetrahydrofuran), 2.12 × 10^-31 and 2.54 × 10^-31 esu (chloroform), 3.06 × 10^-31 and 2.54 × 10^-31 esu (dichloromethane), and 1.27 × 10^-31 and 1.50 × 10^-31 esu (toluene), respectively. This study found that substitution at the α position has an effect of lowering the two-photon (2PA) cross section value for α-SnOtBpPc compared to that for β-SnOtBpPc, with values of 64.30 and 456.65 GM, respectively. The large 2PA cross section observed in β-SnOtBpPc is attributed to the decreased energy difference between the virtual state and the LUMO.

Photophysical and nonlinear optical study of benzothiazole substituted phthalocyanines in solution and thin films

In this study, the photophysical, nonlinear absorption and nonlinear optical limiting properties of zinc and gallium phthalocyanine complexes: tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato]zinc(II) (3), tetrakis[(benzo[d]thiazol-2-yl phenoxy)phthalocyaninato] gallium(III) chloride (4), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] zinc(II) (5), tetrakis[(benzo[d]thiazol-2-ylthio)phthalocyaninato] gallium(III) chloride (6), were investigated both in solution and when embedded in polystyrene thin films using 532 nm laser excitation at 10 ns pulses. It was also observed that complexes that have higher triplet state absorption also possessed enhanced nonlinear and optical limiting behavior. Superior optical performance was observed when the complexes were embedded in thin films compared to when they are in solution. Complex 6 in thin films gave the highest imaginary third-order susceptibility (I[Formula: see text][X[Formula: see text]]) and hyperpolarizability ([Formula: see text] at 4.61 × 10[Formula: see text] esu and 3.44 × 10[Formula: see text] esu, respectively, with a low I[Formula: see text] value of 0.06 J.cm[Formula: see text]

Synthesis, photophysical and nonlinear optical properties of a series of ball-type phthalocyanines in solution and thin films

Ball-type phthalocyanines containing heavy central metals show enhanced nonlinear optical behaviour in solution or when embedded in polymer thin films. Time dependent density functional theory (TD-DFT) calculations were used to explain the spectra.

Optical limiters with improved performance based on nanoconjugates of thiol substituted phthalocyanine with CdSe quantum dots and Ag nanoparticles

Grafting of thiolated phthalocyanine onto quantum dots and nanoparticles provided conjugates with prominent optical limiting.

Improvement of nonlinear optical properties of phthalocyanine bearing diethyleneglycole chains: Influence of symmetry lowering vs. heavy atom effect

This paper reports the successful synthesis of the low symmetry phthalocyanines: metal-free 2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-[Formula: see text]-butoxyphthalocyanine 1H[Formula: see text] and its zinc complex 1Zn along with their nonlinear optical (NLO) behavior in solution and in thin films. 1H NMR investigations evidenced of higher dissymmetry of electronic density in 1H[Formula: see text] in comparison with 1Zn. This dissymmetry is responsible for unusually higher values of Im[[Formula: see text]]/[Formula: see text], [Formula: see text], and [Formula: see text] for 1H[Formula: see text]in contrast to 1Zn, where the notable effect of heavy-metal enhancement of ISC was expected. Both compounds showed Im[[Formula: see text]]/[Formula: see text] values of the order of 10[Formula: see text] in chloroform which are higher in comparison to the symmetrical octabutoxyphthalocyanine H2[(BuO)8Pc]. NLO properties of 1H[Formula: see text] were improved via its incorporation into polycarbonate polymeric matrix together with CdSe@CdS-TOPO quantum dots. In such composite the value of Im[[Formula: see text]]/[Formula: see text] was almost three times higher in comparison with 1H[Formula: see text] solution in chloroform. The obtained composites are expected to be perspective components of optical materials, capable of protection against strong light irradiation.

Powder-XRD and (14) N magic angle-spinning solid-state NMR spectroscopy of some metal nitrides

Some metal nitrides (TiN, ZrN, InN, GaN, Ca3 N2 , Mg3 N2 , and Ge3 N4 ) have been studied by powder X-ray diffraction (XRD) and (14) N magic angle-spinning (MAS) solid-state NMR spectroscopy. For Ca3 N2 , Mg3 N2 , and Ge3 N4 , no (14) N NMR signal was observed. Low speed (νr  = 2 kHz for TiN, ZrN, and GaN; νr  = 1 kHz for InN) and 'high speed' (νr  = 15 kHz for TiN; νr  = 5 kHz for ZrN; νr  = 10 kHz for InN and GaN) MAS NMR experiments were performed. For TiN, ZrN, InN, and GaN, powder-XRD was used to identify the phases present in each sample. The number of peaks observed for each sample in their (14) N MAS solid-state NMR spectrum matches perfectly well with the number of nitrogen-containing phases identified by powder-XRD. The (14) N MAS solid-state NMR spectra are symmetric and dominated by the quadrupolar interaction. The envelopes of the spinning sidebands manifold are Lorentzian, and it is concluded that there is a distribution of the quadrupolar coupling constants Qcc 's arising from structural defects in the compounds studied.

Optical limiting and singlet oxygen generation properties of phosphorus triazatetrabenzcorroles

Novel phosphorus triazatetrabenzcorrole (TBC) tetrasubstituted at the α- and β-positions of the peripheral fused benzene rings with t-butylphenoxy substituents have been prepared and characterized. The effect of the substituents on the electronic structures and optical properties is investigated with TD-DFT calculations and MCD spectroscopy. The optical limiting properties have been investigated to examine whether the lower symmetry that results from the direct pyrrole–pyrrole bond and hence the permanent dipole moment that is introduced result in higher safety thresholds, relative to the values that have been reported for phthalocyanines. The suitability of the compounds for singlet oxygen applications has also been examined.

Exposure to Helicobacter pylori infection in early childhood and the risk of allergic disease and atopic sensitization: a longitudinal birth cohort study

Background

An inverse relation between Helicobacter pylori infection and allergic disease has been reported by a range of independent epidemiological studies, but evidence from longitudinal studies is scarce.

Objective

We have investigated the effects of H. pylori infection on the incidence and prevalence of allergic diseases and sensitization in a low-income birth cohort.

Methods

In 2005/2006, a population-based birth cohort was established in Butajira, Ethiopia, and the 1006 singleton babies born were followed up at ages 1, 3, and 5. Symptoms of allergic disease were collected using the ISAAC questionnaire, allergen skin tests performed, and stool samples analysed for H. pylori antigen and geohelminths. Multiple logistic regression was used to determine the independent effects of H. pylori measured at age 3 on the incidence of each outcome between ages 3 and 5 years (in those without the outcome at age 3), controlling for potential confounders, and to additionally assess cross-sectional associations.

Results

A total of 863 children were followed up to age 5. H. pylori infection was found in 25% of the children at both ages 3 and 5, in 21% at age 5 but not 3, and in 17% at age 3 but not at age 5. H. pylori infection at age 3 was significantly associated with a decreased risk of incident eczema between ages 3 and 5 (adjusted OR, 95% CI, 0.31; 0.10–0.94, P = 0.02). Cross-sectionally at age 5, H. pylori infection was inversely associated with skin sensitization (adjusted OR, 95% CI, 0.26; 0.07–0.92, P = 0.02).

Conclusion and clinical relevance

These findings provide further evidence to suggest that early-life exposure to H. pylori may play a protective role in the development of allergy.

Large-aperture wide-bandwidth antireflection-coated silicon lenses for millimeter wavelengths

The increasing scale of cryogenic detector arrays for submillimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n=3.4, low loss, and high thermal conductivity is a nearly optimal material for these purposes but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating. We have fabricated silicon lenses as large as 33.4 cm in diameter with micromachined layers optimized for use between 125 and 165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30° with low cross polarization. We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to submillimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.

Risk factors for wheezing in infants born in Cuba

BACKGROUND

Cuba is a unique country, and despite limited economic development, has an excellent health system. However, the prevalence of asthma symptoms in children in Havana, Cuba, is unusually high.

AIM

As early life exposures are critical to the aetiology of asthma, we have studied environmental influences on the risk of wheezing in Cuban infants.

DESIGN

Cross-sectional study.

METHODS

A random sample of 2032 children aged 12-15 months living in Havana was selected for inclusion in the cohort. Data were collected using questionnaires administered by researchers.

RESULTS

Of 2032 infants invited to participate, 1956 (96%) infants provided data. The prevalence of any wheeze was 45%, severe wheeze requiring use of emergency services was 30% and recurrent wheeze on three or more occasions was 20%. The largest adjusted risk factors for any wheeze were presence of eczema [odds ratio (OR) 2.09; 95% confidence interval (CI) 1.48-2.94], family history of asthma (OR 2.05; 95% CI 1.60-2.62), poor ventilation in the house (OR 1.99; 95% CI 1.48-2.67), attendance at nursery (OR 1.78; 95% CI 1.24-2.57), male sex (OR1.52; 95% CI 1.19-1.96) and the number of smokers in the house (P < 0.03 for trend), OR 1.64 (95% CI 1.17-2.31) for three or more smokers in the house compared to no smokers in the household.

CONCLUSION

We have identified several risk factors for any wheeze in young infants living in modern day Cuba. As the prevalence of smoking in the house is high (51%), intervention studies are required to determine effective strategies to improve infant health.

Third order nonlinear optical properties of phthalocyanines in the presence nanomaterials and in polymer thin films

Third order nonlinear optical properties were determined for phthalocyanine complexes 1–10 containing In , Ga and Zn central metals and tetra- or octa-substituted with benzyloxyphenoxy, phenoxy, tert-butylphenoxy and amino groups at peripheral or non-peripheral positions. The phthalocyanines were embedded in poly (methyl methacrylate) polymer in the presence of CdTe quantum dots. All complexes 1–10 were studied in the presence of CdTe quantum dots and embedded in poly (methyl methacrylate) to form thin films. Complex 3 tetrasubstituted with tert-butylphenoxy groups at non-peripheral positions was also studied in the presence of CdS , CdSe quantum dots, fullerenes, single walled carbon nanotubes. Third order nonlinear optical parameters generally increase for Pcs in the presence of CdTe quantum dots.