J Phys Chem B. 2010 Nov 16. [Epub ahead of print]

Influence of Sequence on the Self-Assembly of Peptide Nanoribbons on Silicon Substrates.

Dhathathreyan A, Nair BU.

Chemical Lab, CLRI (CSIR), Adyar, Chennai 600020, India.

Abstract

This work reports the formation of stable nanoassemblies of short pentapeptides LKLKL (pepI) and their mutated sequence LKKLL (pepII) obtained from their Langmuir-Blodgett films transferred onto hydrophilic and hydrophobic silicon substrates. The adsorption and assembly of the LB films of these peptides on solid surfaces have been studied by quartz crystal microbalance, surface plasmon resonance, and scanning electron microscopy. Both pepI and pepII assemble into nanosized ribbons, with diameters around 20-25 nm and lengths greater than 5 μm on hydrophobic surface, and tend to aggregate on hydrophilic surfaces with pepII showing twisted structures. Circular dichroic spectra of the films on a hydrophobic surface showed formation of a β-sheet-like structure, while the corresponding solution spectra did not show any specific secondary structure. Our results demonstrate the formation of a two-dimensional dense array of nanoassemblies with either vertical or horizontal patterns from such short peptides that may find application in nanotechnology.

PMID: 21080677 [PubMed - as supplied by publisher]

Ann Indian Acad Neurol. 2010 Jul;13(3):216-220.

Cerebral amyloid angiopathy: A clinicopathological study of three cases.

Panicker JN, Nagaraja D, Chickabasaviah YT.

Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore - 560 029, India.

Abstract

Cerebral amyloid angiopathy (CAA) is an important cause for intracerebral hemorrhage (ICH), yet often goes undiagnosed in the absence of histological examination of the blood vessels in the clot. In this study, we report three patients who presented with ICH. Two patients had no risk factors for bleed, whereas one patient had systemic hypertension. Tissue for analysis was obtained during hematoma evacuation in two patients and necropsy in the third. Histopathology in all three patients revealed severe degree of amyloid angiopathy with extensive amyloid deposits in the vessel walls, which was diagnostic of CAA. Both medium- and small-sized leptomeningeal and cortical vessels were affected. The vascular amyloid deposits stained with Congo red and displayed characteristic birefringence under polarizing light. In addition, vessels also showed fibrinoid necrosis and vascular endothelial proliferation. Immunohistochemistry demonstrated beta-amyloid peptide in all three cases-the protein most commonly involved in sporadic CAA. Senile plaques with amyloid cores were present in all areas, whereas neurofibrillary tangles were restricted to the medial temporal region in the autopsied case. CAA is an important cause for intracerebral bleed and may be a contributory factor even when other risk factors for ICH are present. Areas of hemorrhage tend to correlate with severity of CAA changes.

PMID: 21085537 [PubMed - as supplied by publisher]

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India Peptides ~Cholesterol-lowering statins 'kill bacteria'

Cholesterol-lowering statins 'kill bacteria'

Washington, Nov 18 : A recent clinical research suggests that statins, widely prescribed for their cholesterol-lowering properties, can reduce the risk of severe bacterial infections such as pneumonia

and sepsis.

Researchers at the University of California, San Diego School of Medicine and Skaggs School of Pharmacy and Pharmaceutical Sciences, found that phagocytes (white blood cells that kill and ingest harmful bacteria, foreign particles and dead or dying cells) became more effective after being exposed to statins.

Victor Nizet, professor of pediatrics and pharmacy, and Christopher Glass, professor of medicine and cellular and molecular medicine, the UC San Diego team, led the study.

The researchers also found that statins stimulated the phagocytes to release "extracellular traps" - specialized webs of DNA-based filaments embedded with anti-microbial peptides and enzymes capable of ensnaring and killing bacteria before they spread in the body.

Glass said that the findings have broad ramifications given the popularity of statins for controlling high cholesterol levels.

"Clinical research indicates that perhaps 100 million Americans have elevated cholesterol levels that could benefit from statin therapy. Thus any statin-associated changes to immune system function are certain to impact millions of people," said Glass.

Prior research had described various anti-inflammatory properties of statins, suggesting that these effects could contribute to a reduction in disease severity during severe infections.

The UCSD findings demonstrate that statins have important pharmacological effects beyond inhibiting cholesterol production.

"We found these drugs fundamentally alter how white blood cells behave upon encountering bacteria. In our studies with staph bacteria, the net effect of statin treatment was to improve bacterial killing and extracellular trap formation. These same changes might not be so consequential for defense against less virulent bacteria that are easily susceptible to uptake and killing within phagocytes," said Nizet.

The research also sheds important new light on the clinical phenomenon of reduced infection severity in patients receiving statins, the scientists said. It indicates that levels of cholesterol or related lipid molecules can be sensed by white blood cells and used as signals to control their inflammatory and antibacterial activities.

The research is published in the issue of Cell Host and Microbe.

Transcriptional profiling of antimicrobial peptides avian β-defensins in the chicken ovary during sexual maturation and in response to Salmonella ente

Res Vet Sci. 2010 Nov 9. [Epub ahead of print]

Transcriptional profiling of antimicrobial peptides avian β-defensins in the chicken ovary during sexual maturation and in response to Salmonella enteritidis infection.

Michailidis G, Avdi M, Argiriou A.

Laboratory of Physiology of Reproduction of Farm Animals, Department of Animal Production, School of Agriculture, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.

Abstract

Avian β-defensins (AvβDs) are antimicrobial peptides that play significant roles in the innate immune system in chickens. The aim of this study was to identify the types of AvβDs expressed in the chicken ovary, to investigate the effects of sexual maturation in the ovarian mRNA abundance and to determine the changes in their expression levels as a result to Salmonella enteritidis (SE) infection. RNA was extracted from the ovary of healthy prepubertal, sexually mature and aged birds, as well as from sexually mature and aged SE infected birds. Real-time PCR analysis revealed that 11 AvβDs genes were expressed in the chicken ovary. A significant up regulation of AvβD1, 3, 4, 5, 7 and 11 was observed in the ovary of sexually mature and aged birds. Furthermore, a significant up-regulation of AvβD4, 5, 7, 11 and 12 was observed in the ovary of SE infected sexually mature birds. These results suggest that the mRNA expression of at least six AvβDs increase with age in the ovary of laying hens, and that at least five AvβDs show an induction in their expression in response to SE infection, indicating an AvβD-mediated immune response mechanism in the chicken ovary.

Copyright © 2010. Published by Elsevier India Pvt Ltd.

PMID: 21071048 [PubMed - as supplied by publisher]

Peptides India~Nanotechnology could unlock secret of youthful skin

Nanotechnology could unlock secret of youthful skin
Monday - Nov 22, 2010, 03:27pm (GMT+5.5)

London-An expert at University of Reading, UK, is examining the use of nanotechnology to restore skin's youthfulness.

Collagen growth has long been seen as the ultimate prize for makers of anti-ageing skin cream. Now there is a clue to how an ingredient in some anti-wrinkle treatments may stimulate this growth and restore skin's elasticity.

Ian Hamley is trying to find out how the compound Matrixyl works by studying the nanoscale arrangement of its long carbon chain and the peptide of five amino acids attached to one end.

Similar compounds containing peptides made up of fewer amino acids tend to form cylindrical structures, with all the long chains pointing inwards and the peptides pointing outwards, reports New Scientist.

In Matrixyl, however, such cylinders are outnumbered by flat "nanotapes", in which the molecules are lined up in two layers with all the peptides on the upper and lower surfaces.

The flat surfaces formed by nanotapes may facilitate the build-up of collagen, he said.

Hamley hopes that this work will help research into regenerative medicine for injuries to collagen-containing tissue such as skin and the eye.

However, what happens when you actually apply it to skin is still unknown, says Christopher Griffiths at the University of Manchester, UK.

The study is published in Chemical Communications.

Read more: http://www.indiavision.com/news/article/scitech/127289/#ixzz164E6QfkY

Chemistry. 2010 Oct 13. [Epub ahead of print]

Short-Peptide-Based Hydrogel: A Template for the In Situ Synthesis of Fluorescent Silver Nanoclusters by Using Sunlight.

Adhikari B, Banerjee A.

Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700 032 (India), Fax: (+91) 332473-2805.

Abstract

N-terminally Fmoc-protected dipeptide, Fmoc-Val-Asp-OH, forms a transparent, stable hydrogel with a minimum gelation concentration of 0.2 % w/v. The gelation property of the hydrogel was investigated by using methods such as transmission electron microscopy, field-emission scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy. The silver-ion-encapsulating hydrogel can efficiently and spontaneously produce fluorescent silver nanoclusters under sunlight at physiological pH (7.46) by using a green chemistry approach. Interestingly, in the absence of any conventional reducing agent but in the presence of sunlight, silver ions were reduced by the carboxylate group of a gelator peptide that contains an aspartic acid residue. These clusters were investigated by using UV/Vis spectroscopy, photoluminescence spectroscopy, high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) studies. Mass spectrometric analysis shows the presence of a few atoms in nanoclusters containing only Ag(2). The reported fluorescent Ag nanoclusters show excellent optical properties, including a very narrow emission profile and large Stokes shift (>100 nm). The reported fluorescent Ag nanoclusters within hydrogel are very stable even after 6 months storage in the dark at 4 °C. The as-prepared hydrogel-nanocluster conjugate could have applications in antibacterial preparations, bioimaging and other purposes.

PMID: 20945315 [PubMed - as supplied by publisher]

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