Second Data Release from the European Pulsar Timing Array: Challenging the Ultralight Dark Matter Paradigm.

Pulsar Timing Array experiments probe the presence of possible scalar or pseudoscalar ultralight dark matter particles through decade-long timing of an ensemble of galactic millisecond radio pulsars. With the second data release of the European Pulsar Timing Array, we focus on the most robust scenario, in which dark matter interacts only gravitationally with ordinary baryonic matter. Our results show that ultralight particles with masses 10^{-24.0} eV≲m≲10^{-23.3} eV cannot constitute 100% of the measured local dark matter density, but can have at most local density ρ≲0.3 GeV/cm^{3}.

Peracetic acid: a practical agent for sterilizing heat-labile polymeric tissue-engineering scaffolds.

Advanced biomaterials and sophisticated processing technologies aim at fabricating tissue-engineering scaffolds that can predictably interact within a biological environment at the cellular level. Sterilization of such scaffolds is at the core of patient safety and is an important regulatory issue that needs to be addressed before clinical translation. In addition, it is crucial that meticulously engineered micro- and nano- structures are preserved after sterilization. Conventional sterilization methods involving heat, steam, and radiation are not compatible with engineered polymeric systems because of scaffold degradation and loss of architecture. Using electrospun scaffolds made from polycaprolactone, a low melting polymer, and employing spores of Bacillus atrophaeus as biological indicators, we compared ethylene oxide, autoclaving and 80% ethanol to a known chemical sterilant, peracetic acid (PAA), for their ability to sterilize as well as their effects on scaffold properties. PAA diluted in 20% ethanol to 1000 ppm or above sterilized electrospun scaffolds in 15 min at room temperature while maintaining nano-architecture and mechanical properties. Scaffolds treated with PAA at 5000 ppm were rendered hydrophilic, with contact angles reduced to 0°. Therefore, PAA can provide economical, rapid, and effective sterilization of heat-sensitive polymeric electrospun scaffolds that are used in tissue engineering.

Mineralization Potential of Electrospun PDO-Hydroxyapatite-Fibrinogen Blended Scaffolds.

The current bone autograft procedure for cleft palate repair presents several disadvantages such as limited availability, additional invasive surgery, and donor site morbidity. The present preliminary study evaluates the mineralization potential of electrospun polydioxanone:nano-hydroxyapatite : fibrinogen (PDO : nHA : Fg) blended scaffolds in different simulated body fluids (SBF). Scaffolds were fabricated by blending PDO : nHA : Fg in the following percent by weight ratios: 100 : 0 : 0, 50 : 25 : 25, 50 : 50 : 0, 50 : 0 : 50, 0 : 0 : 100, and 0 : 50 : 50. Samples were immersed in (conventional (c), revised (r), ionic (i), and modified (m)) SBF for 5 and 14 days to induce mineralization. Scaffolds were characterized before and after mineralization via scanning electron microscopy, Alizarin Red-based assay, and modified burnout test. The addition of Fg resulted in scaffolds with smaller fiber diameters. Fg containing scaffolds also induced sheet-like mineralization while individual fiber mineralization was noticed in its absence. Mineralized electrospun Fg scaffolds without PDO were not mechanically stable after 5 days in SBF, but had superior mineralization capabilities which produced a thick bone-like mineral (BLM) layer throughout the scaffolds. 50 : 50 : 0 scaffolds incubated in either r-SBF for 5 days or c-SBF for 14 days produced scaffolds with high mineral content and individual-mineralized fibers. These mineralized scaffolds were still porous and will be further optimized as an effective bone substitute in future studies.

Supramolecular control during triplet sensitized geometric isomerization of stilbenes encapsulated in a water soluble organic capsule.

Triplet sensitized photoisomerization of several stilbenes included within a water-soluble organic capsule has been investigated. In this study octa acid that self assembles in the presence of hydrophobic guest molecules to form a host-guest complex is utilized to solubilize hydrophobic stilbenes and triplet sensitizers in water, and to provide confinement during the geometric isomerization of included olefins. By monitoring the steady state and time resolved room temperature phosphorescence from 4,4'-dimethylbenzil in the presence of acceptor stilbenes and their nitrogen analogues (stilbazole and bispyridyl ethylene) we have been able to establish that triplet-triplet energy transfer occurs between encapsulated donors and encapsulated (or free) acceptors. The mechanism of the energy transfer process is yet to be fully understood although a similar phenomenon has been reported earlier in the literature with Cram's hemicarcerand as the host. The photostationary state composition of cis and trans isomers within the OA capsule is dependent on the relative binding strength of the two isomers with the OA capsule. Further investigation is needed to fully exploit the interesting observations made here to steer the photoisomerization towards a single isomer.

Studies on the cardioprotective role of gallic acid against AGE-induced cell proliferation and oxidative stress in H9C2 (2-1) cells.

Epidemiological studies have shown that high glucose levels and oxidative stress cause elevation of advanced glycation end products (AGEs) that are known to contribute to diabetic complications. Thus, agents that hamper reactive oxygen species (ROS) load can be used as a potential drug against AGEs-mediated complications. Hence, the present study investigated the protective role of gallic acid (GA) against the effects of AGEs in cardiac H9C2(2-1) cells. Exposure of cells to AGEs resulted in release of ROS (P < 0.05) with significant (P < 0.05) decline in antioxidant enzyme levels and increase in collagen (P < 0.01) content. In addition, the altered mitochondrial membrane potential (mmp) (P < 0.01) was also observed in cells exposed to AGEs, whereas AGEs-exposed cells pretreated with GA prevented the release of ROS, and there were no significant changes in the antioxidant status, collagen content and mmp. Thus, the results of the present study provide evidence that GA exhibits protective role against AGEs-induced cardiovascular complications probably through its free radical scavenging activity.

Electrospinning adipose tissue-derived extracellular matrix for adipose stem cell culture.

Basement membrane-rich extracellular matrices, particularly murine sarcoma-derived Matrigel, play important roles in regenerative medicine research, exhibiting marked cellular responses in vitro and in vivo, although with limited clinical applications. We find that a human-derived matrix from lipoaspirate fat, a tissue rich in basement membrane components, can be fabricated by electrospinning and used to support cell culture. We describe practical applications and purification of extracellular matrix (ECM) from adipose tissue (At-ECM) and its use in electrospinning scaffolds and adipose stem cell (ASC) culture. The matrix composition of this purified and electrospun At-ECM was assessed histochemically for basement membrane, connective tissue, collagen, elastic fibers/elastin, glycoprotein, and proteoglycans. Each histochemical stain was positive in fat tissue, purified At-ECM, and electrospun At-ECM, and to some extent positive in a 10:90 blend with polydioxanone (PDO). We also show that electrospun At-ECM, alone and blended with PDO, supports ASC attachment and growth, suggesting that electrospun At-ECM scaffolds support ASC cultivation. These studies show that At-ECM can be isolated and electrospun as a basement membrane-rich tissue engineering matrix capable of supporting stem cells, providing the groundwork for an array of future regenerative medicine advances.

Age-related auditory deficits in temporal processing in F-344 rats.

Older human listeners demonstrate perceptual deficits in temporal processing even when audibility has been controlled. These age-related auditory deficits in temporal processing are thought to originate in the central auditory pathway. Precise temporal processing is necessary to detect and discriminate auditory cues such as modulation frequency, modulation depth and envelope shape which are critical for perception of speech and environmental sounds. This study aims to further understanding of temporal processing in aging using non-invasive electrophysiological measurements. Amplitude modulation following responses (AMFRs) and frequency modulation following responses (FMFRs) were recorded from aged (92-95-weeks old) and young (9-12-weeks old) Fischer-344 (F-344) rats for sinusoidally amplitude modulated (sAM) tones, sinusoidally frequency modulated (sFM) tones and ramped and damped amplitude modulation (AM) stimuli which differ in their envelope shapes. The modulation depth for the sAM and sFM stimuli and envelope shape for the ramped and damped stimuli were systematically varied. There was a monotonic decrease in AMFR and FMFR amplitudes with decreases in modulation depth across age for sAM and sFM stimuli. There was no significant difference between the response amplitudes of the young and aged animals for the largest modulation depths. However, a reduction in modulation depth resulted in a significant decrease in the response amplitudes and higher modulation detection thresholds for sAM and sFM stimuli with age. The aged animals showed significantly lower response amplitudes for ramped stimuli but not for damped stimuli. Cross correlating the responses with the ramped, symmetric, or damped stimulus envelopes revealed a decreased fidelity in encoding envelope shapes with age. These results indicate that age related temporal processing deficits become apparent only with reduced modulation depths or when discriminating envelope shapes. This has implications for psychophysical or diagnostic testing as well as for constraining potential cellular and network mechanisms responsible for these deficits.

Visual acuity outcomes after deep anterior lamellar keratoplasty: a case-control study.

AIM: To compare visual outcomes between deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK). Secondarily to compare refractive outcomes, complications and graft survival between the three cohorts. METHODS: Retrospective case-control study evaluating visual acuity outcomes (VA) following DALK with complete Descemet's baring (DALKa) (modified Anwar big bubble technique--51 eyes), pre-descemetic anterior lamellar keratoplasty (DALKm) (manual technique--52 eyes) and PK (103 eyes) with mean follow-up of 13.6, 19.3 and 18.6 months, respectively. RESULTS: The common indications for surgery were corneal scars (36.4%), keratoconus (28.6%) and corneal dystrophies (13.6%). A best-corrected VA of 6/7.5 or better was achieved in 19.4% (PK), 21.6% (DALKm) and 38.5% (DALKa) of cases (p=0.02), and eyes that underwent DALKa had significantly better visual outcomes than PK (p=0.03). Complications following PK were glaucoma (15%), endothelial rejection (12%) and epithelial problems (11%); in the lamellar group, glaucoma (9%), epithelial problems (5%) and Descemet's detachment (3%) were more common. The 2-year estimated probability of graft survival was 90% for PK, 98% for DALKm and 100.0% for DALKa (p=0.35). CONCLUSIONS: Lamellar keratoplasty with complete baring of the Descemet's membrane (DALKa) gave significantly better visual outcomes compared to PK or pre-descemetic ALK and should be the preferred from of corneal replacement in corneal disorders with healthy endothelium.

Evidence-based National Vaccine Policy.

India has over a century old tradition of development and production of vaccines. The Government rightly adopted self-sufficiency in vaccine production and self-reliance in vaccine technology as its policy objectives in 1986. However, in the absence of a full-fledged vaccine policy, there have been concerns related to demand and supply, manufacture vs. import, role of public and private sectors, choice of vaccines, new and combination vaccines, universal vs. selective vaccination, routine immunization vs. special drives, cost-benefit aspects, regulatory issues, logistics etc. The need for a comprehensive and evidence based vaccine policy that enables informed decisions on all these aspects from the public health point of view brought together doctors, scientists, policy analysts, lawyers and civil society representatives to formulate this policy paper for the consideration of the Government. This paper evolved out of the first ever ICMR-NISTADS national brainstorming workshop on vaccine policy held during 4-5 June, 2009 in New Delhi, and subsequent discussions over email for several weeks, before being adopted unanimously in the present form.

Acquired perforating dermatoses in patients with diabetic kidney disease on hemodialysis.

Acquired perforating dermatoses (APD) is an uncommon skin disorder seen in patients with diabetes mellitus, chronic kidney disease, or both together. We present the clinicopathological features of APD in patients with diabetic kidney disease and discuss the recent advances in management. We retrospectively analyzed the data of 8 patients with APD presenting to our center. All patients were known cases of Type 2 diabetes and chronic kidney disease requiring maintenance dialysis. Acquired perforating dermatoses was diagnosed based on clinical presentation of itchy, keratotic papulonodular lesions, and characteristic histopathological features of transepithelial elimination on skin biopsy. The patients were subdivided into 4 types of APD based on the biopsy features. All our patients had Type 2 diabetes over 5 years duration and were on maintenance dialysis for more than 6 months before presentation. Acquired perforating dermatoses symptoms appeared 2 to 6 months before presentation. The majority of patients (6/8) had a subtype of reactive perforating collagenosis. All the patients showed significant resolution with topical glucocorticoid therapy. Acquired perforating dermatoses is a skin complication seen in Type 2 diabetes, chronic kidney disease, or when both are present together. Early identification and therapy prevents the associated morbidity.

Multiple factor interactions in biomimetic mineralization of electrospun scaffolds.

One of the major limitations in scaffold-based bone tissue engineering has been the inability to increase the loading of biologically active inorganic mineral. The present study introduces a novel two step strategy to increase overall mineral content of electrospun scaffolds and employs multiple factor interaction as a statistic to identify the combination of factors that yields maximal scaffold mineralization. Different amounts of nHA (0, 10, 25 and 50% by wt. of polymer) were electrospun in combination with polydioxanone (PDO) or poly(glycolide: lactide) to generate composite scaffolds. Successful incorporation of nHA within, on and in between nanofibers was confirmed by transmission and scanning electron microscopy. These scaffolds were immersed in different types (conventional, revised, ionic and modified) of simulated body fluid (SBF), prepared at 1x and 4x concentrations and the incubation was carried out either in static or dynamic setting at biomimetic conditions. At 2 weeks, the total amount of mineral within the scaffold was quantified using a modified Alizarin Red-based assay. Each of the five independent factors was analyzed independently and tested for interaction using random effects ANOVA. Statistics revealed significant higher order interactions among factors and the combination of PDO containing 50% nHA incubated in 1x revised SBF resulted in maximum mineralization.

[Topical inhibition of angiogenesis at the cornea. Safety and efficacy]. / Topische antiangiogene Therapie an der Hornhaut. Sicherheit und Effektivität.

BACKGROUND: The efficacy and safety of novel topical inhibitors of corneal neovascularisation will be discussed. METHODS: A literature review after a PUBMED search and own clinical and experimental results are presented. RESULTS: The off-label use of Avastin eye drops and GS101 eye drops against insulin receptor substrate (IRS)-1, which have been tested in phase II trial, both seem to be relatively efficient and safe ways to inhibit progressive corneal neovascularisation. Other VEGF antagonists, such as ranibizumab and pegaptanib eye drops also inhibit corneal neovascularisation. CONCLUSIONS: Avastin and GS101 eye drops are the first specific angiogenesis inhibitors for topical inhibition of corneal angiogenesis available for clinical use.

Science of nanofibrous scaffold fabrication: strategies for next generation tissue-engineering scaffolds.

Native extracellular matrix (ECM) provides structural support to the multicellular organism on a macroscopic scale and establishes a unique microenvironment (niche) to tissue- and organ-specific cell types. Both these functions are critical for optimal function of the organism. These natural ECMs comprise predominantly fibrillar proteins, collagen and elastin and are synthesized as monomers but undergo hierarchical organization into well-defined nanoscaled structural units. The interaction between the cells and ECM is dynamic, reciprocal and essential for tissue development, maintenance of function, repair and regeneration processes. Tissue-engineering scaffolds are synthetic, biomimetic ECM analogues that have great promise in regenerative medicine. Ongoing efforts in mimicking the native ECM in terms of composition and dimension have resulted in three strategies that permit the generation of scaffolds in nanometer dimensions. Although excellent reviews regarding the applications of these strategies in tissue engineering are available, a comprehensive review of the science behind these fabrication techniques does not exist. This review intends to fill this critical gap in the existing knowledge in the fast-expanding field of nanofibrous scaffolds. A thorough understanding of the fabrication processes would enable us to better exploit available technologies to produce superior tissue-engineering scaffolds.

Osteo-odonto-keratoprosthesis surgery: a combined ocular-oral procedure for ocular blindness.

The aim of this retrospective study was to describe the oral procedures used in osteo-odonto-keratoprosthesis (OOKP) surgery, and the demographics and oral findings of candidate patients in Singapore. The OOKP procedure utilizes an autologous tooth-bone complex to mount a poly-methylmethacrylate optical cylinder, as an artificial cornea, stabilized by an overlying autologous buccal mucosal graft. Consecutive patients referred over 3 years for dental evaluation prior to OOKP surgery were included. A total of 21 patients underwent oral clinical and radiographic evaluation. The aetiology of blindness included Stevens-Johnson's syndrome (11 cases), chemical burns (9 cases) and multiple failed corneal grafts (1 case). Evaluation revealed that 12 patients were suitable for OOKP surgery, 8 were at risk of complication or failure and 1 had no usable teeth. Fourteen patients have undergone unilateral OOKP Stage 1 surgery successfully. Complications included fracture of a tooth from its lingual bone necessitating the harvesting of a second tooth (1 case), oronasal perforation (1 case), exposure of adjacent roots (5 teeth), lower lip paresthesia (2 cases) and submucosal scar band formation in the buccal mucosal graft donor site (10 cases). Thirteen patients have completed Stage 2 surgery, with attainment of their best possible visual potential following OOKP surgery.

Controversies in BCG immunization.

Despite controversies BCG vaccination has stood the test of time. World Health Organization continues to recommend its use in infant immunization programme in countries with heavy endemicity and where threatening HIV epidemic in an emerging problem > 85% efficacy have been established in recent years against hematogenous spread of the disease and > or = 50% efficacy even against pulmonary tuberculosis. Host related factors, agent related factors, vaccine related factors and inadequacy of evaluation tests determine the BCG vaccine efficacy. Identification of complete BCG genome in 1998 has opened new vistas in newer BCG vaccine development. Adoption of a '5C' concept viz. Case detection, Chemotherapy short course, Contact elimination, Chemoprophylaxis and lastly control in BCG vaccine will be a desirable national approach in combating adult and childhood TB.

Oxidative DNA damage in the aging mouse brain.

The brain exhibits regional vulnerabilities to many insults, and age itself has differential effects on neuronal populations as exemplified by the age-dependent loss of dopaminergic neurons in the nigrostriatal system. We hypothesized that oxidative damage to DNA was more likely to occur in the nigrostriatal system which undergoes significant neurochemical and functional changes with age. To test this hypothesis, oxidative damage to DNA, indicated by levels of 8-hydroxy2'-deoxyguanosine (oxo8dG), was measured in pons-medulla (PM), midbrain (MB), caudate-putamen (CP), hippocampus (HP), cerebellum (CB), and cerebral cortex (CX) at 3, 18, and 34 months of age in C57/b1 mice. Steady-state levels of oxo8dG increased significantly with age in MB, CP, and CB, but not in PM, HP, or CX. Manganese superoxide dismutase (MnSOD) activity decreased with age in MB, CP, and HP, but not in PM, CB, or CX. Regional activities of Cu/Zn superoxide dismutase (Cu/Zn SOD) and glutathione peroxidase (Glut Px) did not change significantly with age. Concomitant with the regional alterations in DNA damage, there was a significant age-dependent decline in locomotor activity, motor coordination, and striatal dopamine content especially during the interval between 18 and 34 months. In conclusion, oxyradical-associated damage to DNA did not accumulate uniformly across brain regions with age and was highest in brain regions that subserve spontaneous locomotor activity and motor coordination.

Attenuation of age-dependent oxidative damage to DNA and protein in brainstem of Tg Cu/Zn SOD mice.

Age-dependent accumulation of oxidative DNA and protein damage in brainstem and striatum was assessed in normal and transgenic (tg) mice which overexpress human Cu/Zn superoxide dismutase (h-SOD1). A marker of oxidative DNA damage, 8-hydroxy-2'-deoxyguanosine (oxo8dG), was measured at 3, 12, and 18 months of age in control and tg mice. Cu/Zn SOD, but not MnSOD, activities in brainstems and striata from tg mice were increased compared to controls at all ages. At 18 months, oxo8dG levels were increased by 58% in brainstem and by 21% in striatum of control mice. In the tg mice, brainstem and striatal oxo8dG levels were increased to a lesser extent than in the corresponding controls. Protein oxidation (carbonyl content), was increased by 59% at 18 months in control brainstem, but not in striatum, and the increase was significantly attenuated in the tg mice. In summary, oxidative damage to DNA and protein increased with age in brainstem (and to a lesser extent in striatum), and augmented Cu/Zn SOD activity modified the extent of DNA and protein damage.