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Deep learning provides an excellent avenue for optimizing diagnosis and patient monitoring for clinical-based applications, which can critically enhance the response time to the onset of various conditions. For cardiovascular disease, one such condition where the rising number of patients increasingly outweighs the availability of medical resources in different parts of the world, a core challenge is the automated classification of various cardiac abnormalities. Existing deep learning approaches have largely been limited to detecting the existence of an irregularity, as in binary classification, which has been achieved using networks such as CNNs and RNN/LSTMs. The next step is to accurately perform multi-class classification and determine the specific condition(s) from the inherently noisy multi-variate waveform, which is a difficult task that could benefit from (1) a more powerful sequential network, and (2) the integration of clinical notes, which provide valuable semantic and clinical context from human doctors. Recently, Transformers have emerged as the state-of-the-art architecture for forecasting and prediction using time-series data, with their multi-headed attention mechanism, and ability to process whole sequences and learn both long and short-range dependencies. The proposed novel multi-modal Transformer architecture would be able to accurately perform this task while demonstrating the cross-domain effectiveness of Transformers, establishing a method for incorporating multiple data modalities within a Transformer for classification tasks, and laying the groundwork for automating real-time patient condition monitoring in clinical and ER settings., Comment: 18 pages, 11 figures, submitted to Artificial Intelligence in Medicine journal

A novel series of N-Mannich bases of benzimidazole derivatives were synthesized and characterized by (1)H NMR, IR spectral studies and elemental analysis. The compounds were screened for analgesic and anti-inflammatory activity. 1-((Diethylamino)-methyl)-2-styryl benzimidazole 4 at 40mg/kg was found to be equipotent to paracetamol. 1-((Piperidin-1-yl) methyl)-2-styryl-benzimidazole 6 at 40mg/kg was found to be more potent than Diclofenac. Corneal permeability and quantum chemical calculations were performed to correlate the hydrogen bonding ability with permeability and activity. The energies of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were correlated with pharmacological activity. The semi-empirical PM3 calculations (quantum chemical calculations) revealed that E(LUMO) and energy gap DeltaE were capable of accounting for the high in vitro bovine corneal permeability and activity of the compounds.

Widespread cerebral deposition of a 40-42 amino acid peptide called amyloid beta peptide (A beta) in the form of amyloid fibrils is one of the most prominent neuropathologic features of Alzheimer's disease (AD). The clinical study provides evidence that accumulation of protofibrils due to the Arctic mutation (E22G) causes early AD onset. Melatonin showed beneficial effects in an AD mouse model. Mice were divided into four different groups (n=8 per group): (i) control group, (ii) scrambled A beta-injected group, (iii) A beta protofibril-injected group and (iv) melatonin-treated group. A single dose of (5 microg) A beta protofibril was administered to the A beta protofibril-injected and melatonin-treated groups via intracerebroventricular injections. The results demonstrate that melatonin treatment significantly reduces A beta protofibril-induced reactive oxygen species (ROS) production, intracellular calcium levels and acetylcholinesterase activity in the neocortex and hippocampus regions. Based on these findings it is suggested that melatonin therapy might be a useful treatment for AD patients.

Oral hepatitis B vaccine formulation was prepared by successful encapsulation of immunogenic peptide representing residues 127–145 of the immunodominant B-cell epitope of hepatitis B surface antigen (HBsAg) in poly( d , l -lactide co-glycolide) (PLG) microparticles. The smooth, spherical PLG microparticles with a diameter of around 10 μm was prepared by using W/O/W double emulsion solvent evaporation method. The entrapment efficiency of B-cell epitope peptide (BCEP) into PLG microparticles was 64%. In vitro studies showed B-cell epitope loaded PLG microparticles (BCEM) released the peptide in sustained profile and reached 64.9% efficiency by Day 25. Single oral immunization of mice with BCEM led to the significant induction of specific serum IgG and IgM anti-HB antibodies. After the termination of antibody induction, the orally immunized mice were infected with HBsAg, which resulted in the rapid production of antibodies against HBsAg as a result of secondary immune response. PLG microparticles formulation approach may have potential in increasing the efficacy of microparticulate systems for the oral administration of hepatitis B vaccine.

Prion protein fragments that are extracted from the brains of patients with Gerstmann-Straussler-Scheinker disease are known to have stimulating action on circulating leukocytes. In particular, the amyloidogenic hydrophobic prion peptide HuPrP (113-127) AGAAAAGAVVGGLGG has been reported to be associated with significant cellular toxicity. In this paper we show that the self assembled form of HuPrP (113-127) and its valine rich domains viz. GAVVGGLG [HuPrP (119-126)] and VVGGLGG [HuPrP (121-127)] are toxic to peripheral lymphocytes. To explore the cytotoxic mechanism of these fragments, we studied 3-(4,5-dimethylthiazol-2yl)-2-5-diphenyltetrazolium bromide (MTT) reduction, reactive oxygen species (ROS) generation, calcium influx and raft sequestration of' peptide treated lymphocytes. Langmuir monolayer studies on these peptides showed a maximum lipid perturbing property of HuPrP (121-127) as compared to the other two fragments. MTT reduction assays on lymphocytes treated with peptides indicated that the prion peptide fibrils are relatively more toxic than freshly solubilized peptide preparations. Lymphocytes treated with HuPrP (121-127), HuPrP (113-127) and HuPrP (119-126) fibrils underwent 60%, 30% and 40% cell death, respectively. Abeta(1-42), HuPrP (119-126) and HuPrP (121-127) fibrils caused 4 fold increases in intracellular ROS as compared with control cells. However, HuPrP (113-127) fibrils lacked such a significant ROS generating activity, indicating that a subtle difference in sequence leads to a difference in the toxic mechanism in the cell. HuPrP (119-126) and HuPrP (121-127) fibrils also produced maximum raft sequestration and calcium influx. Taken together, these data suggest that the assemblage of prion fragments has significant toxic activity on peripheral lymphocytes, a finding with implications for controlling reactive lymphocytes in prion infected subjects.

Contraceptive steroids levonorgestrel (LNG) and ethinyl estradiol (EE) have been encapsulated with poly(ϵ-caprolactone) (PCL) microspheres using a w/o/w double emulsion method. The microspheres prepared were smooth and spherical, with a mean size from 8–25 μm. In vitro release profiles of microspheres showed a trend of increasing initially at the first week, and thereafter the release was sustained. At the end of the seventh week LNG/EE from 1:5 and 1:10 PCL microspheres were 60 and 48%, 52 and 46%, respectively. An in vitro degradation study shows that at the 20th week the microspheres maintained the surface integrity. The PCL microspheres showed a triphasic in vivo release profile with an initial burst effect due to the release of the steroid adsorbed on the microsphere surface, a second sustained release phase due to the steroid diffusion through the pores or channels formed in the polymer matrix, and third phase due to polymer bioerodible. Histological examination of PCL microspheres injected intramuscularly into thigh muscle of a rat showed a minimal inflammatory reaction demonstrating that contraceptive steroid-loaded microspheres were biocompatible. The level of inflammatory cytokines determined by immunostaining for IL-1α, the tissue response to formulations at the first week was considered mild, whereas at the end of the 20th week the inflammatory response ceased. Thus, this study helped us to evaluate the feasibility of using these microspheres as a long-acting biodegradable drug delivery system for contraceptive steroids. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006

An antifungal protein produced by Bacillus polymyxa strain VLB16 has been purified to homogeneity by ammonium sulfate precipitation and Sephadex-G-200 column chromatography. The purified protein inhibited the growth of Pyricularia grisea and Rhizoctonia solani , the causative agents of rice blast and sheath blight diseases, respectively. Microscopy studies revealed that the antifungal protein caused severe alterations in cell morphogenesis that gave rise to swollen and rounded hyphae. The protein was a monomer with molecular weight of 37 kDa in sodium dodecyl sulfate-poly acrylamide gel electrophoresis and gave a single symmetrical peak in gel permeation chromatography. The presence of predominant random coil structure and other conformations such as β-sheet and β-turn was noticed from Fourier transform infra red spectroscopy. The protein was heat stable and remained active after sterilization at 121 °C for 15 min. The antifungal protein was resistant to hydrolysis by pronase and also to many protein-denaturing detergents like sodium dodecyl sulfate (SDS), hexa decyl trimethyl ammonium bromide (HDTMA) and Tween-20. The extraordinary thermo-stability of the protein can be of good prospect to be used as a new tool for biocontrol.

Collagen is one of the best materials used for nerve guide preparation due to its biocompatibility and desirable tensile strength. In this work, we have compared regeneration and functional reinnervation after sciatic nerve resection with bioresorbable crosslinked collagen guides in 10 mm gap. The crosslinking was carried out either with glutaraldehyde (GTA) or microwave irradiation (MWI). The multilayered collagen membrane used for nerve guides are prepared by lamellar evaporation technique. Functional evaluations of the regenerated nerves were performed by measuring the sciatic functional index (SFI), nerve conduction velocity (NCV), and electromyography (EMG). Transmission electron microscopic studies showed growth of axonal cable with fewer myelinated axons, Schwann cells and more unmyelinated axons present in the case of group treated with uncrosslinked collagen tubes after 1 month of implantation. However, we have observed more myelinated axons in the case of autograft, GTA, and MWI crosslinked collagen tube implants across the gap of 1 cm after the same period of implantation. Smaller myelinated fiber diameter was observed in the case of GTA crosslinked collagen tube group when compared with the autograft and MWI collagen tube groups. There were more myelinated axons during the 3rd and 6th months postoperatively using these conduits as substantiated by light microscopic studies of the regenerated nerve. The conduction velocity and recovery index improved significantly after 5 months reaching the normal values in the autograft and MWI crosslinked collagen groups compared to GTA and uncrosslinked collagen tubes.

Neurotrophic factors play an important modulatory role in axonal sprouting during nerve regeneration involving the proliferation of hematogenous and Schwann cells in damaged tissue. We have exposed lesioned sciatic nerves to a collagen prosthesis with covalently bonded small cell adhesive peptides Arg-Gly-Asp-Ser (RGDS), Lys-Arg-Asp-Ser (KRDS), and Gly-His-Lys (GHK) to study local production of growth factors and cytokines in the regenerating tissues. Western/enzyme-linked immunosorbent assay (ELISA) studies were performed after 10 days of regeneration, when the tubular prosthesis is filled with fibrous matrix infiltrated by hematogenous cells and proliferating Schwann cells with growth factors produced locally. Regeneration was also analyzed by morphometrical methods after 30 days. The quantification of growth factors and proteins by ELISA revealed that there was an enhanced expression of the neurotrophic factors nerve growth factor (NGF) and neurotrophins (NT-3 and NT-4) in the regenerating tissues. This was further established by Western blot to qualitatively analyze the presence of the antigens in the regenerating tissues. Schwann cells were localized in the regenerating tissues using antibodies against S-100 protein. Other growth factors including growth-associated protein 43 (GAP-43), apolipoprotein E (Apo E), and pro-inflammatory cytokine like interleukin-1alpha (IL-1alpha) expression in the peptide groups were evaluated by ELISA and confirmed by Western blotting. Cell adhesive integrins in the proliferating cells were localized using integrin-alpha V. The combined results suggest that the early phase of regeneration of peripheral nerves in the presence of peptide-incorporated collagen tubes results in the enhanced production of trophic factors by the recruited hematogenous cells and Schwann cells, which in turn help in the secretion of certain vital trophic and tropic factors essential for early regeneration. Furthermore, hematogenous cells recruited within the first 10 days of regeneration help in the production of inflammatory mediators like interleukins that in turn stimulate Schwann cells to produce NGF for axonal growth.

Successful nerve regeneration process was achieved with improved mechanical strength by crosslinking tubular nerve guides made up of collagen. The multilayered collagen sheets were prepared from laminar evaporation of collagen solution. Scanning electron micrograph of the collagen tubes crosslinked with glutaraldehyde (GTA), microwave irradiation showed porous, fibrillar structures of collagen filaments in these matrices. The mechanical property of the crosslinked collagen tubes was carried out by tensile strength measurements. Fourier transform infrared spectra of the collagen films show that the native triple helicity was unaltered during multilayered preparation. It was observed that the structural integrity is unaltered during the multilayer preparation. Microscopic analysis indicates that the tubule surface acts as a surface of adherence and proliferation for the sprouting axons from the cut proximal nerve stumps. Solute diffusion studies on these tubes indicate that they are highly porous to wide range of molecular sizes during regeneration. Among the two types of crosslinking, the microwave irradiated collagen conduits results in ample myelinated axons compared with GTA group, where we observed more unmyelinated axons.

This study evaluated the effects of noncovalently incorporated crystallin into the collagen matrix for dermal wound-healing processes in rats. Crystallin-incorporated collagen matrix (CIC) showed better healing when compared to wounds treated with collagen matrix (CS) and without collagen (CR). Biochemical parameters and histological analysis revealed that increased wound contraction enhanced cell proliferation and efficient radical scavenging in the CIC group. The higher shrinkage temperature of CIC films when compared to CS groups suggested increased hydrothermal stability for the former material. An in vitro release study of CIC has showed sustained and time-dependent release of crystallin from the collagen matrix. These results demonstrate the possibility of using crystallin as therapeutic protein in the wound-healing process.

Amyloid β (Aβ) peptides are one of the classes of amphiphilic molecules that on dissolution in aqueous solvents undergo interesting conformational transitions. These conformational changes are known to be associated with their neuronal toxicity. The mechanism of structural transition involved in the monomeric Aβ to toxic assemblage is yet to be understood at the molecular level. Early results indicate that oriented molecular crowding has a profound effect on their assemblage formation. In this work, we have studied how different microenvironments affect the conformational transitions of one of the active amyloid β-peptide fragments (Aβ25–35). Spectroscopic techniques such as CD and Fourier transform infrared spectroscopy were used. It was observed that a stored peptide concentrates on dissolution in methanol adopts a minor α-helical conformation along with unordered structures. On changing the methanol concentration in the solvated film form, the conformation switches to the antiparallel β-sheet structure on the hydrophilic surface, whereas the peptide shows transition from a mixture of helix and unordered structure into predominantly a β-sheet with minor contribution of helix structure on the hydrophobic surface. Our present investigations indicate that the conformations induced by the different surfaces dictate the gross conformational preference of the peptide concentrate. © 2004 Wiley Periodicals, Inc. Biopolymers (Pept Sci), 2004

This paper describes the regeneration of lesioned sciatic nerve with collagen tubes incorporated with RGD cell-adhesive peptide. Collagen implants of 14 mm were grafted to bridge a gap length of 10 mm nerve defect in a rat model. The regenerated tissues were analyzed histomorphologically. The number of myelinated axons in the regenerated mid-graft of the RGD peptide incorporated groups was statistically significant (p

Present study describes the development of a new formulation of levonorgestrel and ethinylestradiol based on double emulsion-solvent evaporation technique using poly(epsilon-caprolactone) (PCL) as biodegradable polymer. The effect of polymer concentration on microspheres and entrapment of drug into microspheres were studied. PCL was selected because of its hydrophobicity and advantages over other biodegradable polymers. Characterization of biodegradable polymer used for controlled drug delivery is essential to ensure reproducibility of in vitro and in vivo performances. The selected characterisation techniques established for PCL microspheres include its loading and entrapment efficiencies, DSC to analyse thermal behaviour, SEM to observe surface morphology, drug content of microspheres and in vitro release of drugs from microspheres. The SEM reports showed that microspheres were with smooth surface and DSC thermograms revealed no interaction between drug and polymer. The entrapment was found to be 58 and 47% for 1:10 and 1:5 batches and in vitro release studies showed that about 69.7% of LNG and 66.7% of EE from 1:10 batch and about 80% of LNG and 75.5% of EE from 1:5 batch for 150 days.

Two tetrapeptide derivatives [peptide A (Boc–Ala–Ile–Ile–Gly–OMe) and peptide B (Boc–Ala–Ile–Leu–Ser–OMe)], that take helical turn conformation in solution, were shown to form monolayer at the air/water interface. Circular dichroism (CD) measurements indicate that peptide A has more helical turn propensity than peptide B in sodium dodecyl sulphate (SDS) micelles. Langmuir–Blodgget film study of peptides A and B suggest that both the peptides form stable monolayer at the air/water interface. Spectroscopic investigations reveal that peptide A forms helical turn assemblage on transferring the film into hydrophilic quartz and hydrophobic ZnSe surfaces. Whereas, peptide B adopts β-sheet structure on hydrophilic surface and a mixture of β-sheet and helical turn conformation on hydrophobic surface.

Conformational transitions are thought to be the prime mechanism of amyloid formation in prion diseases. The prion proteins are known to exhibit polymorphic behavior that explains their ability of "conformation switching" facilitated by structured "seeds" consisting of transformed proteins. Oligopeptides containing prion sequences showing the polymorphism are not known even though amyloid formation is observed in these fragments. In this work, we have observed polymorphism in a 15-residue peptide PrP (113-127) that is known to form amyloid fibrils on aging. To see the polymorphic behavior of this peptide in different solvent environments, circular dichroism (CD) spectroscopic studies on an aqueous solution of PrP (113-127) in different trifluoroethanol (TFE) concentrations were carried out. The results show that PrP (113-127) have sheet preference in lower TFE concentration whereas it has more helical conformation in higher TFE content (40%). The structural transitions involved in TFE solvent were studied using interval-scan CD and FT-IR studies. It is interesting to note that the alpha-helical structure persists throughout the structural transition process involved in amyloid fibril formation implicating the involvement of both N- and C-terminal sequences. To unravel the role of the N-terminal region in the polymorphism of the PrP (113-127), CD studies on another synthetic peptide, PrP (113-120) were carried out. PrP(113-120) exhibits random coil conformation in 100% water and helical conformation in 100% TFE, indicating the importance of full-length sequence for beta-sheet formation. Besides, the influence of different chemico-physical conditions such as concentration, pH, ionic strength, and membrane like environment on the secondary structure of the peptide PrP (113-127) has been investigated. At higher concentration, PrP (113-127) shows features of sheet conformation even in 100% TFE suggesting aggregation. In the presence of 5% solution of sodium dodecyl sulfate, PrP (113-127) takes high alpha-helical propensity. The environment-dependent conformational polymorphism of PrP (113-127) and its marked tendency to form stable beta-sheet structure at acidic pH could account for its conformation switching behavior from alpha-helix to beta-sheet. This work emphasizes the coordinative involvement of N-terminal and C-terminal sequences in the self-assembly of PrP (113-127).

Self-assembly of β-sheet domains resulting in the formation of pathogenic fibrillar protein aggregates (amyloids) is the causative factor in Alzheimer's, Huntington's, and Creutzfeldt−Jakob disease...

Conductometry, circular dichroism and fluorescence spectroscopy are thetechniques employed to investigate the effect of added calcium ions and other monovalent and divalent metal ions on aqueous solutions of nonionic peptide aggregates, Boc-Leu-Asn-OEt (1). It is observed that among all the metal ions studied, Ca2+ ions facilitate the aggregation of the peptide. The interior dielectric constant of the micelles (e) was found to depend upon the proportion of Ca2+ complexed peptide with the peptide monomers in the micelles. When Ca2+ ion becomes 1/4th of the peptide concentration, there is a structural transition leading to drastic change in the interior of the micro dielectric constant (em).

Density and sound velocity measurements and1H NMR investigations were carried out in aqueous solution at various temperatures for determining the adiabatic compressibility (β) and hydration of the tetrapeptide, TFA. Tyr-Gly-Phe-Ala-Obz I. The present investigation showed changes in the temperature coefficient of adiabatic compressibility at 40°C,1H NMR studies indicated the inverse temperature transition in the concentration range studied.

We have studied the binding of hemoglobin to the red cell membrane by centrifugation and fluorescence methods. The intact red cell was labeled with eosin-5-maleimide (EM), which specifically reacts with lysine 430 of band 3. Even though this residue is not part of the cytoplasmic domain of band 3 (cdb3) associated with hemoglobin binding, fluorescence quenching was observed when hemoglobin bound to inside-out vesicles (IOVs). The use of fluorescence quenching to measure band 3 binding was quantitatively compared with the binding determined by centrifugation, which measures binding to band 3 and non-band 3 sites. For the centrifugation it was necessary to include the non-band 3 association constants determined from chymotrypsin-treated IOVs. The binding of hemoglobin to band 3 was interpreted in terms of the binding of two hemoglobin tetramers to each band 3 dimer. An anticooperative interaction associated with the conformational change produced when hemoglobin binds results in a 2.8-fold decrease in the intrinsic constant of (1.54 +/- 0.25) x 10(7) M(-1) for the binding of the second hemoglobin molecule. From the changes in lifetime produced by binding the first and second hemoglobin molecules, it was possible to show that the conformational change associated with binding the second hemoglobin molecule results in a decrease of the heme-eosin distance from 47.90 to 44.78 A. Reaction of cyanate with the alpha-amino group of hemoglobin (HbOCN) is shown to produce a very dramatic decrease in the binding of hemoglobin to both the band 3 and non-band 3 sites. The intrinsic constant for binding the first hemoglobin molecule to band 3 decreases by a factor of 29 to (5.34 +/- 0.15) x 10(5) M(-1). The anticooperative interaction is greater with the intrinsic constant decreasing by a factor of 3.8 for the binding of the second hemoglobin tetramer to band 3. In addition, the nature of the conformational change produced by binding hemoglobin is very different with the second HbOCN increasing the heme-eosin distance to 55.99 A. The utilization of eosin-5-maleimide-reacted red cell membrane to study hemoglobin binding makes it possible to directly study the binding to band 3. At the same time a sensitive probe of the conformational changes, which occur when hemoglobin binds to band 3, is provided.

Isoproterenol hydrochloride (ISO), a beta adrenergic agonist, is known to cause ischemic necrosis in rats. Cardiotoxicity of three different doses of ISO were studied using physiological, biochemical and histopathological parameters. The effects of single and double dose of ISO were analysed, which illustrated that single ISO dose was more cardiotoxic than double ISO dose due to ischemic preconditioning. The tetrapeptide derivatives L-lysine-L-arginine-L-aspartic acid-L-serine (tetrapeptide A) and di-tert.butyloxycarbonyl-L-lysine-L-arginine-L-aspartic acid-tert.butyl O-tert.butyl-L-serinate (tetrapeptide B) along with acetylsalicylic acid as positive control were analysed at different time points for their cardioprotective effect. The results demonstrated that optimal protective effects were observed by pretreatment with 5 mg/kg of tetrapeptide B and this was found to be slightly better than that of acetylsalicylic acid. A lesser degree of cardioprotection was noticed when low doses of tetrapeptide B were administered. This study clearly showed that single dose of ISO (50 mg/kg, s.c.) induced myocardial necrosis could be used as a model to assess cardiovascular drugs and in this model, it was demonstrated that the tetrapeptide B could exhibit optimal cardioprotective effect.

A novel surfactant peptide consisting of an arginine cation with laurate anion has been synthesized, purified and characterized. The critical micellar concentration (cmc) of peptide in aqueous solutions has been determined using spectroscopic techniques and is found to increase from 0.06 to 0.11 mM with increasing temperature (15–45°C). Cmc is also determined in the presence of salts like NaCl, KCl and sodium acetate and it is found that these electrolytes hinder aggregation with a significant increase in the case of sodium acetate. The aggregation number of the surfactant peptide has been determined using fluorescence quenching measurements and is observed to decrease from 14 to 6 with increasing temperature (15–45°C). The standard free energy change (ΔG m 0 ) and standard enthalpy change (ΔH m 0 ) of the peptide aggregate are found to be negative with a small positive value for standard entropy change (ΔS m 0 ). The peptide aggregate seems to undergo phase transition above 50°C as observed from UV-vis and fluorescence spectroscopy. From pyrene binding studies, it is shown that the interior dielectric constant increases from 5.08 at 34°C to 8.77 at 50°C and further decreases with increase in temperature indicating a phase change at 50°C. Also, the ratio of excimer intensity to monomer intensity, which is a measure of microviscosity of the aggregate, decreases with increase in temperature with a change at 50°C indicating a phase change.

The tetrapeptide derivative Boc-Ile-Gly-Met-Thr(Bzl)-OBzl 1 forms micellar aggregates in chloroform. Evidence for micelle formation in chloroform has been obtained by IR, Raman scattering, fluorescence spectroscopic methods and calcium picrate extraction techniques. The thermodynamic data indicate that the driving force for the micellisation is enthalpic in nature.

was prepared (0.1, 0.2, 0.3, 0.6, and 0.8 M) and added slowly to the aqueous mannitol solutions (0.1, 0.2, 0.3, 0.6, and 0.8 M, respectively) placed in the thermostat. The specific conductance of the solution was recorded. The abrupt change in the initial slope value at a particular concentration was considered to be the cmc. Fluorescence spectra were recorded on a Hitachi model 65040 fluorimeter. The aggregation number of SDS in mannitol solutions was determined by the fluorescence quenching method 6

The conformational analysis of N-{N - [(tert-butyloxy) Carbonyl] -L- valyl} - N, N -dicyclohexyl urea 1 in DMSO-d6 has been performed using 1H NMR spectroscopic studies. The data provide evidence for the occurence of intramolecular hydrogen bonded NH of ureide proton. Two specific NOEs [NH (DCHU) ↔ CαH (Va1) and NH(Va1) ↔ CαH (Va1) prescribed the presence of β-turn conformation of compound 1 in DMSO-d6.

A novel series of N-Mannich bases of benzimidazole derivatives were synthesized and characterized by (1)H NMR, IR spectral studies and elemental analysis. The compounds were screened for analgesic and anti-inflammatory activity. 1-((Diethylamino)-methyl)-2-styryl benzimidazole 4 at 40mg/kg was found to be equipotent to paracetamol. 1-((Piperidin-1-yl) methyl)-2-styryl-benzimidazole 6 at 40mg/kg was found to be more potent than Diclofenac. Corneal permeability and quantum chemical calculations were performed to correlate the hydrogen bonding ability with permeability and activity. The energies of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) were correlated with pharmacological activity. The semi-empirical PM3 calculations (quantum chemical calculations) revealed that E(LUMO) and energy gap DeltaE were capable of accounting for the high in vitro bovine corneal permeability and activity of the compounds.

The principal component of the amyloid deposits in Alzheimer’s disease is the β-amyloid polypeptide, while in type II diabetes the deposits consist primarily of Islet amyloid polypeptide. These amyloid forming polypeptides consist of highly polymorphic domains, which take different conformations including random coil, helical and β strand depending upon the microenvironment. We have studied major fibril-forming components of IAPP and βAP and demonstrated that conformational polymorphism of these peptides in different microenvironments correlate with cellular toxicity and proteasomal inhibitory activity. On treating with trifluoroethanol (TFE) the peptide fragments undergo structural transition from a random coil to a helical conformation. Even though these domains share the same gross amyloid structural characteristic, their proteasomal activities differ. We found that even the tetrapeptides have significant proteasomal inhibitory activity indicating that the amyloid formation is involved in the enhanced life of the smaller aggregates of full-length and fragment peptides, which could explain the toxicity of these sequences.

AA (amyloid protein A) amyloidosis in mice is markedly accelerated when the animals are given, in addition to an inflammatory stimulus, an intravenous injection of protein extracted from AA-laden mouse tissue. Previous findings affirm that AA fibrils can enhance the in vivo amyloidogenic process by a nucleation seeding mechanism. Accumulating evidence suggests that globular aggregates rather than fibrils are the toxic entities responsible for cell death. In the present study we report on structural and morphological features of AEF (amyloid-enhancing factor), a compound extracted and partially purified from amyloid-laden spleen. Surprisingly, the chief amyloidogenic material identified in the active AEF was diffusible globular oligomers. This partially purified active extract triggered amyloid deposition in vital organs when injected intravenously into mice. This implies that such a phenomenon could have been inflicted through the nucleation seeding potential of toxic oligomers in association with altered cytokine induction. In the present study we report an apparent relationship between altered cytokine expression and AA accumulation in systemically inflamed tissues. The prevalence of serum AA monomers and proteolytic oligomers in spleen AEF is consistent to suggest that extrahepatic serum AA processing might lead to local accumulation of amyloidogenic proteins at the serum AA production site.

Chronically elevated blood glucose levels result in reduced leukocyte function and cell malnutrition, which contribute to a high rate of wound infection and associated healing problems in diabetic patients. In the present study, the role of biotinylated GHK peptide (BioGHK) incorporated collagen biomaterial was tested for wound healing in diabetic rats. The rate of wound contraction and the levels of collagen, uronic acid, protein and DNA in the granulation tissue were determined. Further, the concentration of nitric oxide and other skin antioxidants was also monitored during the study. In diabetic rats treated with BioGHK incorporated collagen (Peptide Incorporated Collagen — PIC), the healing process was hastened with an increased rate of wound contraction. Glutathione (GSH) and ascorbic acid levels in the skin of streptozotocin-induced diabetic rats were higher in the PIC group as compared to control (Untreated) and collagen (Collagen Film — CF) treated groups. Superoxide dismutase (SOD) and catalase (CAT) activity was altered in all the groups. In vitro fibroblast cell culture studies suggest that PIC promotes fibroblast growth. Histological evaluation by haematoxylin–eosin and Masson's trichrome method revealed epithelialization, increased synthesis of collagen and activation of fibroblasts and mast cells in the PIC group. This study provides a rationale for the topical application of BioGHK incorporated collagen as a feasible and productive approach to support diabetic wound healing.

Purpose A controlled-release drug delivery of contraceptive steroids levonorgestrel (LNG) and ethinyl estradiol (EE) has been developed by successful encapsulation of LNG and EE in poly (lactide-co-glycolide) (PLG) microspheres. Materials and Methods Smooth, spherical, steroid-loaded PLG microspheres with a mean size of 10–25 μm were prepared by using the water/oil/water double-emulsion solvent evaporation method. Results In vitro release profiles showed an increased burst release of LNG/EE on Week 1; thereafter, the release was sustained. At the end of Week 7, the release of LNG/EE from 1:5 and 1:10 PLG microspheres was 75.64% and 62.55%. respectively. In vitro degradation studies showed that the PLG microspheres maintained surface integrity up to Week 8 and then eroded completely by Week 20. In an in vivo study, the serum concentration of LNG/EE in rats showed a triphasic release response, with an initial burst release of 8 ng/mL LNG and 14 pg/mL EE on Day 1; thereafter, a controlled release of the drugs to the systemic circulation was maintained until Week 15, maintaining constant drug levels of 2 ng/mL LNG and 3–4 pg/mL EE in the blood. Histological examination of steroid-loaded PLG microspheres injected intramuscularly into the thigh muscle of Wistar rats showed minimal inflammatory reaction, demonstrating that contraceptive-steroid-loaded microspheres were biocompatible. Conclusion This controlled-release and biocompatible nature of the PLG microspheres may have potential application in contraceptive therapy.

Pexiganan (Gly-Ile-Gly-Lys-Phe-Leu-Lys-Lys-Ala-Lys-Lys-Phe-Gly-Lys-Ala-Phe-Val-Lys-Ile-Leu-Lys-Lys), a 22 amino acid peptide, is an analogue of the magainin family of antimicrobial peptides present in the skin of the African clawed frog. Conformational analysis of pexiganan was carried out in different solvent environments for the first time. Organic solvents, trifluoroethanol (TFE) and methanol, were used to study the secondary structural preferences of this peptide in the membrane-mimicking environments. In addition, aqueous (D2O) and dimethyl sulfoxide (DMSO) solutions were also investigated to study the role of hydrogen bonding involved in the secondary structure formation. Fourier transform infrared absorption, vibrational circular dichroism (VCD), and electronic circular dichroism (ECD) measurements were carried out under the same conditions to ascertain the conformational assignments in different solvents. All these spectroscopic measurements suggest that the pexiganan peptide has the tendency to adopt different structures in different environments. Pexiganan appears to adopt an alpha-helical conformation in TFE, a sheet-stabilized beta-turn structure in methanol, a random coil with beta-turn structure in D2O, and a solvated beta-turn structure in DMSO.

The structure of insulin in amyloid fibrillar form has been recently shown as a well folded conformation using cryoelectron microscopy [Jimenez, J.L., Nettleton, E.J., Bouchard, M., Robinson, C.V., Dobson, C.M., Saibil H.R., 2002. The protofilament structure of insulin amyloid fibrils. Proc. Natl. Acad. Sci. USA. 99 9196–9201.]. Most of the amyloid aggregates elicit maximum toxicity in the protofibrillar (PF) intermediate state. Here, we describe PF intermediates of insulin are made-up monomers with flexible conformers. We also show protofibrils have three-dimensionally extended hydrophobic cavity to bind with 1-anilinonaphthalene-8-sulphonate (ANS) molecules. Energy transfer measurement revealed that ANS dye binding site of PF is within the range of FRET distance of insulin tyrosine residues. Significant proportion of β-sheet, helical, and turn structures in the PF form indicate conformational dynamics in the folded chain of insulin in the PF assembled form. Though the conformational flexibility is noticeably present in the assembly, addition of GdnHCl could completely unfold PF into disordered structure suggesting structural “zipping” in the PF form. We have also shown that helical conformer inducing solvent 2,2,2-trifluoroethanol (TFE) could dissociate the PF aggregate indicating possible involvement of β-sheets in contributing to PF stability.

The main objective of this work was to develop a system consisting of polymeric microspheres loaded with steroid drugs. The drugs were encapsulated using biodegradable poly(lactide-co-glycolide) (PLG) and poly(epsilon-caprolactone) (PCL) by double emulsion solvent evaporation method. The lipophilic drugs, levonorgestrel and ethinylestradiol were made soluble by adding ethanol/water mixture. The effects of parameters like polymer concentration and stabilizer concentration were studied on the size, size distribution, surface properties and loading efficiencies of microspheres. The formulated microspheres were smooth, spherical and uniform in shape and size. Fourier transformed infrared spectroscopy and differential scanning calorimetry studies seemed to confirm the absence of chemical interaction between the drugs and the polymers, while the drugs were dispersed in the polymer. The increase in polymer concentrations increased the size as well as the loading efficiency of microspheres. Data obtained in this study demonstrated that the PLG/PCL microspheres may be a suitable polymeric carrier for long acting injectable drug delivery.

The highly conserved ubiquitin-proteasome system (UPS) controls the stability of most nuclear and cytoplasmic proteins and is therefore essential for virtually all aspects of cellular function. We have previously shown that the UPS is impaired in the presence of aggregated proteins that become deposited into cytoplasmic inclusion bodies (IBs). Here, we report that production of protein aggregates specifically targeted to either the nucleus or cytosol leads to global impairment of UPS function in both cellular compartments and is independent of sequestration of aggregates into IBs. The observation of severe UPS impairment in compartments lacking detectable aggregates or aggregation-prone protein, together with the lack of interference of protein aggregates on 26S proteasome function in vitro, suggests that UPS impairment is unlikely to be a consequence of direct choking of proteasomes by protein aggregates. These data suggest a common proteotoxic mechanism for nuclear and cytoplasmic protein aggregates in the pathogenesis of neurodegenerative disease.

Alzheimer's disease is associated with vascular amyloidosis. As blood flows through the microcirculation, red blood cells (RBCs) come in contact with the vasculature. RBCs as well as endothelial cells (ECs) are known to bind beta amyloid fibrils. This suggests that a potential effect of amyloidosis may involve the interactions of RBCs with ECs lining the wall of the blood vessels mediated by amyloid fibrils. We have studied the effect of beta-amyloid peptide[1-40] (Abeta1-40) fibrils on the interactions of murine RBCs with ECs derived from bovine lung microvascular endothelium (BLMVEC) as well as bovine pulmonary arterial endothelium (BPAEC) in culture. We show that the initial incorporation of Abeta fibrils onto either RBCs or ECs cause RBCs to adhere to the ECs with greater affinity for the microvascular cells than the arterial cells. In addition, there is a transfer of Abeta fibrils between the RBCs and the ECs. Both the transfer and adhesion occurs when the amyloid fibrils are on the ECs or on the RBCs. However, with the amyloid fibrils on the RBCs, the adhesion and the transfer are greater than with the fibrils on the ECs. These results suggest that amyloidosis may affect the flow of RBCs through the microcirculation and that RBCs may play a role in propagating amyloidosis through the vasculature.

We report the conformational and toxic properties of two novel fibril-forming prion amyloid sequences, GAVVGGLG (PrP(119-126)) and VVGGLGG (PrP(121-127)). The conformational preferences of these fragments were studied in differing microenvironments of TFE/water mixtures and SDS solution. Interestingly, with an increase in TFE concentration, PrP(119-126) showed a helical conformational propensity, whereas PrP(121-127) adopted a more random coil structure. In 5% SDS, PrP(119-126) showed more alpha-helical content than in TFE solution, and PrP(121-127) exhibited a predominantly random coil conformation. However, both peptides took a random coil conformation in water, and over time the random coil transformed into a beta-sheet structure with a significant percentage of helical conformation and beta-turn structure in PrP(119-126) and PrP(121-127), respectively, as observed with CD spectroscopy. The aged fibrils of PrP(119-126) were insoluble in SDS, and PrP(121-127) was extractable with SDS solution. These fibrils were characterized by transmission electron microscopy. Both PrP(119-126) and PrP(121-127) formed stable monolayer's consisting of multimeric assemblages at the air-water interface. Monomeric PrP(119-126) was more toxic to astrocytes than the control Abeta peptide; however, the fibrillar form of PrP(119-126) was less toxic to astrocytes. PrP(121-127) elicited moderate toxicity in both soluble and fibrillar forms on astrocytes. Furthermore, quenching experiments using acroyl-labeled PrP(119-126) and PrP(121-127) with eosin-labeled synaptosomal membrane revealed that these prion fragments bind to anion-exchange protein. The binding of PrP(119-126) and PrP(121-127) with a membrane microdomain (lipid raft) was also analyzed using pyrenated derivatives. We conclude that the formation of PrP(119-126) and PrP(121-127) fibrils is a concentration-dependent process that involves coil to sheet conversion with aging. PrP(119-126), the sequence with intrinsic helical propensity, is more toxic in monomer form, and the fibril formation in this case seems to be protective to cells. For PrP(121-127), the SDS-soluble fibrils are more cytotoxic, indicating that a higher order assemblage structure is required for cytotoxic activity of this peptide.

The wound healing process involves extensive oxidative stress to the system, which generally inhibits tissue remodeling. In the present study, an improvement in the quality of wound healing was attempted by slow delivery of antioxidants like curcumin from collagen, which also acts as a supportive matrix for the regenerative tissue. Curcumin incorporated collagen matrix (CICM) treated groups were compared with control and collagen treated rats. Biochemical parameters and histological analysis revealed that increased wound reduction, enhanced cell proliferation and efficient free radical scavenging in CICM group. The higher shrinkage temperature of CICM films suggests increased hydrothermal stability when compared to normal collagen films. Spectroscopic studies revealed that curcumin was bound to the collagen without affecting its triple helicity. Further we adopted the antioxidant assay using 2,2'-azobisisobutyronitrile to assess in vitro antioxidant activity of CICM. The antioxidant studies indicated that CICM quenches free radicals more efficiently. This study provides a rationale for the topical application of CICM as a feasible and productive approach to support dermal wound healing.

The conformational studies of peptide derivatives A and B in a gel state were studied by using circular dichroism (CD), Fourier transformed infrared (FTIR), and fluorescence spectroscopic techniques. Birefringence and electron microscopic studies were carried out to characterize the morphological aspects of the fibrils in the gel. The FTIR spectra of the peptides show the absence of free NH in the gel state, implying that the intermolecular hydrogen-bond formation is the driving force for the aggregation. The CD spectrum of the peptide gels shows the presence of antiparallel and parallel β-sheet conformation for peptide derivatives A and B, respectively. Electron microscopic studies (EM) of the peptide derivatives A and B reveal that peptide A formed rigid, rod-like structures without cross-linking and peptide B formed loose fibrils organized into highly noncovalently cross-linked mesh-like structural aggregates. Peptide A was much more soluble in alcoholic solvents than peptide B, and no birefringence was observed with Congo red (CR) staining in the temperature range of 0–80°C. The spectroscopic studies indicate that peptide B consists of domains having a significant amount of β-sheet structure and exhibiting golden yellow birefringence between 53 and 56°C when stained with Congo red. On the other hand, peptide A gives no evidence of birefringence under polarized light. Fluorescence probe binding studies with pyrene in gel state with peptides A and B indicates the polarity in the interior of the aggregates. The data presented in the present work indicate that peptide B forms fibrils, which is similar to amyloid aggregates that are present in biological systems. © 2003 Wiley Periodicals, Inc. Biopolymers 70: 346–354, 2003

Self-assembly of two tripeptide derivatives containing three nonpolar isoleucine moieties and polar oxyethylene groups are studied in methanol. Peptide A [CH3(OCH2CH2)3OCH2CO(Ile)3OCH3] and peptide B [CH3(OCH2CH2)3OCH2CO(Ile)3NH (CH2CH2O)3CH3] take a mixture of unordered and helical conformation at low concentration (8.5×10−4M). However, at high concentration (2×10−3M), both the peptide showed significant increase in the helical conformation. An interesting conformational transition of peptides A and B at various methanol contents was observed in the solvated films of these compounds by spectroscopic methods like the far-uv circular dichroism and Fourier transform infrared (FT-IR) techniques. Peptide B, which contains more polar oxyethylene groups than A, showed a highly cooperative conformational transition when the methanol content was decreased. This transition was characterized by a large increase of β-sheet, retaining a α-helical contribution. Peptide A showed a conformational transition resulting in a β-sheet in the aggregated state. From the CD spectra, the ratio in the ellipticity indicates that peptide B forms twisted antiparallel β-sheet conformation, whereas peptide A takes a parallel β-sheet conformation. The results obtained in this work indicates the role of polar derivatization on the conformational preference of peptides having similar sequence. © 2003 Wiley Periodicals, Inc. Biopolymers 70: 336–345, 2003

Increased neuronal nitric oxide synthase (nNOS) activity was observed during the prodromal period of seizures in various rat brain regions following administration of GABAA receptor antagonist, picrotoxin (PCT). Pretreatment with the selective nNOS inhibitor 7-nitroindazole (7-NI), dose- and time-dependently delayed the onset of clonus with a corresponding decrease in nNOS activity. The threshold dose of antiepileptic drugs (AEDs; diazepam, phenobarbitone and gabapentin) have potentiated the anticonvulsant action by pretreatment with graded doses of 7-NI. The increase in efficacy of anticonvulsant action correlated with a corresponding decrease of PCT-evoked increase in nNOS activity. The present data support a role for abnormal nNOS activity in mechanisms that trigger seizures and suggest a possible NO-mediated interplay between GABAA and glutamate receptors. The results of the present study provide evidence for a trigger role of neuronally produced NO in epileptogenesis induced by PCT and the participation of nNOS inhibitory mechanisms in the action of AEDs.

Amyloid beta-protein (A beta) accumulation in brain is thought to be important in causing the neuropathology of Alzheimer's disease (AD). A beta interactions with both neurons and microglial cells play key roles in AD. Since vascular deposition of A beta is also implicated in AD, the interaction of red cells with these toxic aggregates gains importance. However, the effects of A beta interactions with red blood cells are less well understood. Synthetic amyloid beta-protein (1-40) was labeled with biotin and preincubated at 37 degrees C for 4, 14 and 72 h to produce fibrils. Flow cytometry was used to study the binding of these fibrils to red cells. The amyloid fibrils had a high affinity for the red cell with increased binding for the larger fibrils produced by longer preincubation. Bovine serum albumin (BSA) did not reverse the binding, but actually resulted in a more efficient binding of the A beta fibrils to the red cells. The interaction of A beta with red cells increased the mean cell volume and caused the cells to become more spherical. This effect was greater for the longer fibrils. At the same time the interaction of A beta with red cells produced an increase in their fluorescence measured after 16-h incubation at 37 degrees C. This increase in fluorescence is attributed to the formation of fluorescent heme degradation products. The effect of prior hemoglobin oxidation, catalase inhibition and glutathione peroxidase inhibition indicated that the amyloid-induced oxidative damage to the red cell involved hydrogen peroxide-induced heme degradation. These results suggest that amyloid interactions with the red cell may contribute to the pathology of AD.

We have been developing antioxidants incorporated collagen matrix as a novel biomaterial for various biomedical applications. In this study we made use of quercetin incorporated collagenous matrix for dermal wound healing in rat. Quercetin incorporated collagen (QIC) treated groups were compared with control and collagen (CS) treated animals. QIC treated animal showed a better healing when compared to control and CS treated wound. The biochemical parameters like hydroxyproline, protein, uronic acid content in the healing wound, revealed that there is an increase in proliferation of cells in quercetin treated groups when compared to CS group and there is considerable increase in wound contraction when compared to CS treated group. In addition we adapted the antioxidant assay using 2,2'-azobisisobutryonitrile (AIBN) to assess in vitro antioxidant activity of QIC. The antioxidant studies indicate QIC quench the radicals more efficiently. These results suggested that quercetin incorporated collagen matrix could be a novel dressing material for dermal wound healing.

Collagen, a unique connective tissue protein finds extensive application as biocompatible biomaterial in wound healing, as drug carriers, cosmetics, etc. A study has been undertaken to stabilise Type-I collagen of rat-tail tendon using plant polyphenol (Acacia Mollissima) in the presence of an acrylic polymer. It has been found that collagen fibres pre-treated with acrylic polymer followed by the treatment with Acacia Mollissima exhibited an increase in hydrothermal stability by 25°C. Infrared spectroscopic studies display the changes in the spectral characteristics of native and treated collagen films. Transmission electron microscopic and circular dichroic studies provide an insight into the understanding of the improved stabilisation of collagen, due to treatment with acrylic polymer and plant polyphenols. The study is expected to enhance the biomaterial applications of collagen tissues.

Concentration dependent morphological characteristics of a novel dipeptide derivative Lys-Asp-Lauryl.HBr ( 1 ) has been presented. Evidence for “onion” like vesicle formation at higher concentration (>8.2×10 −3 M) of peptide ( 1 ) in aqueous medium was obtained from conductance and 90° light scattering measurements, and cryo-transmission electron microscopic studies.

A tetrapeptide corresponding to a region of the N-terminal portion of lactotransferrin with hydrophobic alkyl groups at the terminal ends was synthesized and its physicochemical properties as well as its effect on thrombin-stimulated platelet aggregation were examined. The tetrapeptide derivative, in the aggregated state, produced inhibitory effect on platelet aggregation. The concentration dependent activity of the peptide was analyzed in the light of micelle formation, with the micellar aggregate comprising four tetrapeptide units. The unique action of this peptide derivative on the inhibition of platelet aggregation might be useful in the development of potent antithrombotic drugs.

A novel peptide, tert-butyloxycarbonyl-L-arginine-L-proline lauryl ester laurate, synthesised by a solution-phase method, formed micelles in aqueous solutions and was observed to exhibit anticoagulant activity as shown by clotting assays such as the thrombin time (TT) test, the prothrombin time (PT) test and the activated partial thromboplastin time (APTT) test. TT and PT were found to be normal up to a particular concentration of peptide, and above that level they increased with increasing concentration of peptide, while APTT did not exhibit much significance. Conductometric and potentiometric studies showed that the peptide formed a stable micelle, and the anticoagulant activity of this peptide was also compared with a non-arginine-containing peptide (control) known to form micelles. The anticoagulant action in the micellar form could be due to the inhibition of thrombin, as seen from the decrease in amidolytic activity. The inhibitory activity of the peptide was explained in the light of micelle formation.

A new micelle-forming peptide TFA·Tyr-Gly-Phe-Ala-OBz (TFA = trifluoroacetic acid) is synthesised and evidence for its micelle formation obtained from UV–VIS, fluorescence spectroscopy, conductometry and pH techniques; the critical micelle concentration (cmc), standard free-energy change of micelle formation (ΔG°m) and aggregation number of this peptide at 20 °C are 8 × 10 –5 mol dm–3, –28.8 kJ mol –3 and 11, respectively.