Analytical Characterization of Heterogeneities in mRNA-Lipid Nanoparticles Using Sucrose Density Gradient Ultracentrifugation

Rational design and robust formulation processes are critical for optimal delivery of mRNA by lipid nanoparticles (LNPs). Varying degrees of heterogeneity in mRNA-LNPs can affect their biophysical and functional properties. Given the profound complexity of mRNA-LNPs, it is critical to develop comprehensive and orthogonal analytical techniques for a better understanding of these formulations. To this end, we developed a robust ultracentrifugation method for density-based separation of subpopulations of mRNA-LNPs. Four LNP formulations encapsulating human erythropoietin (hEPO) with varying functionalities were synthesized using two ionizable lipids, A and B, and two helper lipids, 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and 1,2-dierucoyl-sn-glycero-3-phosphoethanolamine (DEPE), along with cholesterol and DMG-PEG-2K. Upon ultracentrifugation on a sucrose gradient, a distinct pattern of "fractions" was observed across the gradient, from the less dense topmost fraction to the increasingly denser bottom fractions, which were harvested for comprehensive analyses. Parent LNPs, A-DOPE and B-DOPE, were resolved into three density-based fractions, each differing significantly in the hEPO expression following intravenous and intramuscular routes of administration. Parent B-DEPE LNPs resolved into two density-based fractions, with most of the payload and lipid content being attributed to the topmost fraction compared to the lower one, indicating some degree of heterogeneity, while parent A-DEPE LNPs showed remarkable homogeneity, as indicated by comparable in vivo potency, lipid numbers, and particle count among the three density-based fractions. This study is the first to demonstrate the application of density gradient-based ultracentrifugation (DGC) for a head-to-head comparison of heterogeneity as a function of biological performance and biophysical characteristics of parent mRNA-LNPs and their subpopulations.

Analysis of highly frequent point mutations in glycoprotein C, glycoprotein N, and nucleoprotein of CCHFV

Crimean-Congo hemorrhagic fever virus (CCHFV) is classified among top 10 priority pathogens by World Health Organization. CCHFV belongs to Bunyaviridae family and negative sense ssRNA genome composed of three RNA segments: L, M, and S. RNA viruses show higher mutation rate as compared to DNA viruses. To gain deeper understanding of impact of point mutations in CCHFV M and S segment, mutation profiling, homology modeling, and molecular dynamic (MD) simulation were performed. Structural glycoproteins (glycoprotein C [Gc] and glycoprotein N [Gn]) of CCHFV are important for host-virus interaction and genome packaging, whereas CCHFV nucleoprotein (NP) is crucial for viral replication. Hence, current study is focused on evaluation of eight mutations in structural glycoproteins (Gc: 7 and Gn: 1) of M segment and seven mutations in NP of S segment. All these mutations were highly frequent, with mutation frequency between 0.81 and 1.0 and found to be persistent in the recent strains of CCHFV. Solubility analysis predicted that selected point mutations reduce solubility of Gc protein and increase solubility of Gn and NP proteins. MD simulation study deciphered that A1046V and G1158E in Gc protein, I778T in Gn protein, and H195R in NP protein displayed large deviation and fluctuation, and affected intramolecular interactions. In conclusion, we observed that point mutations could impact structure, stability, and host-virus interaction of protein, and might lead to evolution of new strains for better survival and drug resistance.

An Innovative Approach for Biocontrol of Meloidogyne incognita in Ginger Using Potential Bacteria Isolated from Indian Himalayas

The prevalence of Meloidogyne incognita, a severe root-knot nematode, is alarmingly high in the production of ginger-a main cash crop of Himachal Pradesh, a Himalayan state of India. In order to control this through natural means, the nematicidal potential of plant growth-promoting rhizobacteria (PGPR) against M. incognita was analyzed. This is an effective alternative solution to manage nematode incidence as compared to hazardous chemicals under protected and field cultivation of ginger. In the present study an attempt has been made to isolate, characterize, and identify potential rhizobacteria associated with ginger rhizosphere and endosphere. In total, 169 bacterial isolates were isolated from ginger (Zingiber officinale) rhizosphere and endosphere of 4 different sites of Sirmaur district, screened out for multifarious PGP traits showing positive results. The combined cluster analysis and 16S rRNA genotypic analysis of selected bacterial isolates revealed that Serratia marcescens FS-23, Pseudochrobacter sp. GS-15, Stonotrophomonas pavanii HER-9, Pseudomonas brassicacearum HER-20 and Serratia marcescens IS-2 exhibited highest PGP traits. All tested bacterial isolates were capable of exerting a significant effect on mortality of juvenile M. incognita ranging upto 40-90% in laboratory experiments. Further a consortium of these screened isolates showed 86.67% reduction in gall formation by M. incognita in lab conditions. The remarkable increase to 93.24% with 138.73 q/ha with application of charcoal based bio-formulation of consortium without adding any chemical fertilizer was observed in field trials of Nohradhar of Sirmaur district. An alternative choice as a biocontrol agent as well as for PGP activities, the novel and most robust isolate Serratia marcescens IS-2 had revealed to have a variety of bioactive metabolic products with abilities against nematodes, bacteria, and fungi.

Identification of conserved immunogenic peptides of SARS-CoV-2 nucleocapsid protein

The emergence of the new SARS-CoV-2 variants has led to major concern regarding the efficacy of approved vaccines. Nucleocapsid is a conserved structural protein essential for replication of the virus. This study focuses on identifying conserved epitopes on the nucleocapsid (N) protein of SARS-CoV-2. Using 510 unique amino acid sequences of SARS-CoV-2 N protein, two peptides (193 and 215 aa) with 90% conservancy were selected for T cell epitope prediction. Three immunogenic peptides containing multiple T cell epitopes were identified which were devoid of autoimmune and allergic immune response. These peptides were also conserved (100%) in recent Omicron variants reported in Jan-August 2023. HLA analysis reveals that these peptides are predicted as binding to large number of HLA alleles and 71-90% population coverage in six continents. Identified peptides displayed good binding score with both HLA class I and HLA class II molecules in the docking study. Also, a vaccine construct docked with TLR-4 receptor displays strong interaction with 20 hydrogen bonds and molecular simulation analysis reveals that docked complex are stable. Additionally, the immunogenicity of these N protein peptides was confirmed using SARS-CoV-2 convalescent serum samples. We conclude that the identified N protein peptides contain highly conserved and antigenic epitopes which could be used as a target for the future vaccine development against SARS-CoV-2.Communicated by Ramaswamy H. Sarma.

Solvent‐Free Synthesis of S,N‐Doped Carbon Dots for Extended Visible‐Light‐Induced Oxidase‐Mimicking Activities and Antimicrobial Applications

Photo-oxidase nanozymes are emerging enzyme-mimicking materials that produce reactive oxygen species (ROS) upon light illumination and subsequently catalyze the oxidation of the substrate. Carbon dots are promising photo-oxidase nanozymes due to their biocompatibility and straightforward synthesis. Carbon dot-based photo-oxidase nanozymes become active for ROS generation under UV or blue light illumination. In this work, sulfur and nitrogen doped carbon dots (S,N-CDs) were synthesized by solvent-free, microwave assisted technique. We demonstrated that sulfur, nitrogen doping of carbon dots (band gap of 2.11 eV) has enabled photo-oxidation of 3,3,5,5'-tetramethylbenzidine (TMB) with extended visible light (up to 525 nm) excitation at pH 4. The photo-oxidase activities by S,N-CDs produce Michaelis-Menten constant (K_m ) of 1.18 mM and the maximum initial velocity (V_max ) as 4.66×10^-8  Ms^-1 , under 525 nm illumination. Furthermore, visible light illumination can also induce bactericidal activities with growth inhibition of Escherichia coli (E. coli). These results demonstrate that S,N-CDs can increase intracellular ROS in the presence of LED light illumination.

Utilization of novel bacteriocin synthesized silver nanoparticles (AgNPs) for their application in antimicrobial packaging for preservation of tomato fruit

Introduction

The current need of the food industry is to develop a safe packaging system that maintains the quality of food and prevents its spoilage. Food safety techniques improvised using functional nanoparticles minimize the chances of spoilage by maintaining moisture stability, mechanical strength, and durability and ensuring product safety. In the present study, we synthesized silver nanoparticles using purified bacteriocins obtained from probiotics. Bacteriocin-synthesized AgNPs are eco-friendly and secure packaging solutions that can be utilized in the packaging industry for the storage of food products.

Methods

Crude, partially purified and purified bacteriocin was obtained from three potential probiotic isolates, i.e., Lactobacillus pentosus S6 (KU92122), Lactobacillus crustorum F11 (KT865221) and Lactobacillus spicheri G2 (JX481912). The antimicrobial efficacy of bacteriocin was tested against two food-borne spoilage-causing pathogens, i.e., Bacillus cereus and Staphylococcus aureus. The purified bacteriocin obtained was used for the synthesis of AgNPs. The synthesized AgNPs were characterized using UV-vis spectroscopy, TEM, and SEM techniques. The AgNPs were used for coating cellulose paper. The coated paper was characterized using SEM and was used for the storage of tomato fruit.

Results and discussion

The purified bacteriocin obtained was used for the synthesis of AgNPs. The formation of AgNPs was confirmed by using UV-vis spectroscopy, which showed maximum absorption at 450 nm. Furthermore, we confirm shape and morphology by using Scanning Electron Microscopy (SEM). Transmission Electron Microscopy (TEM) analysis showed the mean size of synthesized AgNPs in the range of 5–20 nm. Bacteriocin-synthesized AgNPs were then used for the coating of cellulose paper with the main motive to avoid spoilage and enhance the shelf stability of tomato fruit during storage. SEM analysis confirmed the coating of AgNPs in the cellulose paper. The enhanced antimicrobial efficacy of different treatments coated paper was observed against B. cereus and S. aureus. Out of all, F11 AgNPs coated paper showed maximum inhibition of 24 mm for S. aureus and 22 mm for B. cereus. The coated paper from three different bacteriocin-synthesized AgNPs, along with silver nitrate (AgNO3) coated and uncoated paper, was used for the storage of tomato fruit for a period of 10 days at room temperature. Changes during storage were determined by analyzing morphological and color changes. Compared to AgNO3 coated and uncoated paper, tomato fruit preserved in F11 AgNPs coated paper maintained and held its appearance and firmness, thereby confirming their effectiveness in the preservation of tomatoes.

Inhaled delivery of a lipid nanoparticle encapsulated messenger RNA encoding a ciliary protein for the treatment of primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) is a respiratory disease caused by dysfunction of the cilia with currently no approved treatments. This predominantly autosomal recessive disease is caused by mutations in any one of over 50 genes involved in cilia function; DNAI1 is one of the more frequently mutated genes, accounting for approximately 5-10% of diagnosed PCD cases. A codon-optimized mRNA encoding DNAI1 and encapsulated in a lipid nanoparticle (LNP) was administered to mice via aerosolized inhalation resulting in the expression human DNAI1 in the multiciliated cells of the pseudostratified columnar epithelia. The spatial localization of DNAI1 expression in the bronchioles indicate that delivery of the DNAI1 mRNA transpires the lower airways. In a PCD disease model, exposure to the LNP-encapsulated DNAI1 mRNA resulted in increased ciliary beat frequency using high speed videomicroscopy showing the potential for an mRNA therapeutic to correct cilia function in patients with PCD due to DNAI1 mutations.

Computational design of immunogenic peptide constructs comprising multiple HLA restricted Dengue virus envelope epitopes

Dengue virus (DENV) is endemic in 100 countries with ability to impact nearly 50% of world population. DENV envelope (E) protein is responsible for viral attachment to host cells and has been target of various countermeasure development efforts. The current study focuses on a consensus computational approach to identify cross-reactive, immunogenic DENV-2 E peptides displaying promiscuity with a wide array of HLA molecules. Four conserved peptides (FP-1, FP-2, FP-3 and FP-4) containing multiple CD8⁺ and CD4⁺ T cell epitopes were identified by employment of various immunoinformatics tools. FP-1, FP-2, FP-3 and FP-4 were estimated to bind with 227, 1787, 1008 and 834 HLA alleles respectively. RMSD values obtained by Molecular docking (CABS-Dock) with 20 HLA alleles (10 each of HLA class I and II) resulted into comparable RMSD values of identified epitopes with native peptides which represents the natural presentation of epitopes to HLA molecules. These peptides were also found to be part of previous experimentally validated immunogenic peptides. Further, a dengue immunogenic peptide construct was generated by linking the four peptides, an adjuvant and a 6x histidine tag. The construct showed strong binding and stability with Toll-like receptor (TLR4). Collectively, these results provide strong evidence in the support of the immunogenic potential of the dengue immunogenic peptide construct. This article is protected by copyright. All rights reserved.

Antibody and T Cell Immune Responses to SARS-CoV-2 Peptides in COVID-19 Convalescent Patients

Identifying immunogenic targets of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is critical to advance diagnostic and disease control strategies. We analyzed humoral (ELISA) and T-cell (ELISpot) immune responses to spike (S) and nucleocapsid (N) SARS-CoV-2 proteins as well as to human endemic coronavirus (eCoV) peptides in serum from convalescent coronavirus disease 2019 (COVID-19) patients from Tatarstan, Russia. We identified multiple SARS-CoV-2 peptides that were reactive with serum antibodies and T cells from convalescent COVID-19. In addition, age and gender associated differences in the reactivity to S and N protein peptides were identified. Moreover, several SARS-CoV-2 peptides tested negatively correlated with disease severity and lung damage. Cross-reactivity to eCoV peptides was analyzed and found to be lower in COVID-19 compared to controls. In this study, we demonstrate the changing pattern of immunogenic peptide reactivity in COVID-19 serum based on age, gender and previous exposure to eCoVs. These data highlight how humoral immune responses and cytotoxic T cell responses to some of these peptides could contribute to SARS-CoV-2 pathogenesis.

Immunogenic SARS-CoV-2 S and N Protein Peptide and Cytokine Combinations as Biomarkers for Early Prediction of Fatal COVID-19

Early indications of the likelihood of severe coronavirus disease 2019 COVID-19 can influence treatments and could improve clinical outcomes. However, knowledge on the prediction markers of COVID-19 fatality risks remains limited. Here, we analyzed and quantified the reactivity of serum samples from acute (non-fatal and fatal) and convalescent COVID-19 patients with the spike surface glycoprotein (S protein) and nucleocapsid phosphoprotein (N protein) SARS-CoV-2 peptide libraries. Cytokine activation was also analyzed. We demonstrated that IgM from fatal COVID-19 serum reacted with several N protein peptides. In contrast, IgM from non-fatal serum reacted more with S protein peptides. Further, higher levels of pro-inflammatory cytokines were found in fatal COVID-19 serum compared to non-fatal. Many of these cytokines were pro-inflammatory and chemokines. Differences in IgG reactivity from fatal and non-fatal COVID-19 sera were also demonstrated. Additionally, the longitudinal analysis of IgG reactivity with SARS-CoV-2 S and N protein identified peptides with the highest longevity in humoral immune response. Finally, using IgM antibody reactivity with S and N SARS-CoV-2 peptides and selected cytokines, we have identified a panel of biomarkers specific to patients with a higher risk of fatal COVID-19 compared with that of patients who survive. This panel could be used for the early prediction of COVID-19 fatality risk.

Arterial stiffness and age moderate the association between physical activity and global cognition in the older adults

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The Merck Sharp & Dohme Corp Program of the Faculty of Medicine of the Université de Montréal The Canadian Institutes of Health Research (CIHR)

Background

The growing concern on the impact of higher arterial stiffness on cognitive decline in older adults, leads to the question of whether non-pharmacological interventions like physical activity should be introduced to correct or diminish the progression of arterial stiffness.

Purpose

The goal of this study is to elaborate a model for arterial stiffness as a moderator for the physical activity and global cognition relationship in function of age. 

Methods

One hundred ten healthy older adults aged 60 to 75 years old (46 men and 64 women) were examined for arterial stiffness (carotid-femoral Pulse Wave Velocity (cf-PWV)), global cognition (Montreal Cognitive Assessment and Mini Mental State Examination) and self-reported physical activity (PACED diary). The double moderation analysis used PROCESS macro for SPSS, where physical activity was included as the independent variable (X), global cognition as the dependent variable (Y), arterial stiffness as moderator 1 (W), and age moderator 2 (Z). This study used a cf-PWV cutoff of 8.5 m/s to identify micro-structural damage in the brain related to arterial stiffness.

Results

Results found that the arterial stiffness x age interaction moderated the effect of physical activity on global cognition (β = -.89, SE = .42, p = .037) (Model: R2 = .15, p = .018). Physical activity had a positive effect on cognition in younger-older adults (aged 60 to 68.5 years) with high arterial stiffness i.e. cf-PWV > 8.5 m/s (β = .57, SE = .222, p = .011, 95% CI .133 to 1.014), and in older-older adults (aged 68.6 to 75 years) with low arterial stiffness i.e. cf-PWV < 8.5 m/s (β = .49, SE = .190, p = .010, 95% CI = .116 to .869). 

Conclusions

These results support targeted physical activity interventions based on age and degree of arterial stiffness, furthering the notion that even daily life physical activity could play an important role in older adults’ cognitive performances.

Physical activity on global cognition Conditional effects of physical activity on global cognition Moderators cf-PWV Age Effect SE p CI < 8.5 m/s < 68.5 years .171 .245 .487 -.315 to .657 < 8.5 m/s > = 68.5 years .574 .222 .011* .133 to 1.014 > = 8.5 m/s < 68.5 years .492 .190 .010* .116 to .868 > = 8.5 m/s > = 68.5 years .002 .180 .990 -.355 to .359 Physical activity conditional effects on global cognition at determined values of arterial stiffness and age. SE: Standard Error, CI: Confidence Interval, cf-PWV: carotid-femoral Pulse Wave Velocity, *p-value<.05.

Mutational Frequencies of SARS-CoV-2 Genome during the Beginning Months of the Outbreak in USA

SARS-CoV-2 has spread very quickly from its first reported case on 19 January 2020 in the United Stated of America, leading WHO to declare pandemic by 11 March 2020. RNA viruses accumulate mutations following replication and passage in human population, which prompted us to determine the rate and the regions (hotspots) of the viral genome with high rates of mutation. We analyzed the rate of mutation accumulation over a period of 11 weeks (submitted between 19th January to 15 April 2020) in USA SARS-CoV-2 genome. Our analysis identified that majority of the viral genes accumulated mutations, although with varying rates and these included NSP2, NSP3, RdRp, helicase, Spike, ORF3a, ORF8, and Nucleocapsid protein. Sixteen mutations accumulated in Spike protein in which four mutations are located in the receptor binding domain. Intriguingly, we identified a fair number of viral proteins (NSP7, NSP9, NSP10, NSP11, Envelop, ORF6, and ORF7b proteins), which did not accumulate any mutation. Limited changes in these proteins may suggest that they have conserved functions, which are essential for virus propagation. This provides a basis for a better understanding of the genetic variation in SARS-CoV-2 circulating in the US, which could help in identifying potential therapeutic targets for controlling COVID-19.

Synergistic inhibition of aggressive breast cancer cell migration and invasion by cytoplasmic delivery of anti-RhoC silencing RNA and presentation of EPPT1 peptide on "smart" particles

Overexpression of RhoC protein in breast cancer patients has been linked to increased cancer cell invasion, migration, and metastases. Suppressing RhoC expression in aggressive breast cancer cells using silencing RNA (siRNA) molecules is a viable strategy to inhibit the metastatic spread of breast cancer. In this report, we describe the synthesis of a series of asymmetric pH-sensitive, membrane-destabilizing polymers engineered to complex anti-RhoC siRNA molecules forming "smart" nanoparticles. Using β-CD as the particle core, polyethylene glycol (PEG) chains were conjugated to the primary face via non-cleavable bonds and amphiphilic polymers incorporating hydrophobic and cationic monomers were grafted to the secondary face via acid-labile linkages. We investigated the effect of PEG molecular weight (2 & 5 kDa) on transfection capacity and serum stability of the formed particles. We evaluated the efficacy of EPPT1 peptides presented on the free tips of the PEG brush to function as a targeting ligand against underglycosylated MUC1 (uMUC1) receptors overexpressed on the surface of metastatic breast cancer cells. Results show that "smart" nanoparticles successfully delivered anti-RhoC siRNA into the cytoplasm of aggressive SUM149 and MDA-MB-231 breast cancer cells, which resulted in a dose-dependent inhibition of cell migration and invasion. Further, EPPT1-targeted nanoparticles demonstrate a synergistic inhibition of cell migration and invasion imparted via RhoC knockdown and EPPT1-mediated signaling via the uMUC1 receptor.

Computing Resonant Inelastic X-Ray Scattering Spectra Using The Density Matrix Renormalization Group Method

We present a method for computing the resonant inelastic x-ray scattering (RIXS) spectra in one-dimensional systems using the density matrix renormalization group (DMRG) method. By using DMRG to address this problem, we shift the computational bottleneck from the memory requirements associated with exact diagonalization (ED) calculations to the computational time associated with the DMRG algorithm. This approach is then used to obtain RIXS spectra on cluster sizes well beyond state-of-the-art ED techniques. Using this new procedure, we compute the low-energy magnetic excitations observed in Cu L-edge RIXS for the challenging corner shared CuO4 chains, both for large multi-orbital clusters and downfolded t-J chains. We are able to directly compare results obtained from both models defined in clusters with identical momentum resolution. In the strong coupling limit, we find that the downfolded t-J model captures the main features of the magnetic excitations probed by RIXS only after a uniform scaling of the spectra is made.

"Smart" Nanoparticles Enhance the Cytoplasmic Delivery of Anti-RhoC Silencing RNA and Inhibit the Migration and Invasion of Aggressive Breast Cancer Cells

Rho-GTPases are small GTP-binding proteins that contribute to the epithelial-to-mesenchymal transition by regulating several cellular processes including organization of the actin cytoskeleton, cell motility, transcription, and cell proliferation. Overexpression of RhoC-GTPases (RhoC) in breast cancer has been implicated in poor disease prognosis due to increased cancer cells invasion, migration, and motility, which warranted its consideration as a therapeutic target for inhibiting breast cancer metastasis. Using silencing RNA (siRNA) molecules to knockdown RhoC expression is a promising approach to inhibit breast cancer metastases. However, transforming anti-RhoC siRNA molecules into a viable therapy remains a challenge due to the lack of a biocompatible carrier that can selectively deliver the RNA cargo into breast cancer cells. We report the use of a degradable, pH-sensitive, β-cyclodextrin (βCD)-based polymeric carrier that condenses anti-RhoC siRNA forming "smart" particles. These smart anti-RhoC particles were efficiently internalized, successfully escaped the endosome, and delivered the RNA cargo into the cytoplasm of SUM149 and MDA-MB-231 breast cancer cells. Our results show that anti-RhoC particles used at a low N/P ratio of 2.5/1 suppressed RhoC protein levels by 100% and 90% in SUM149 and MDA-MB-231 cells, respectively. Further, anti-RhoC particles inhibited the invasion, motility, and migration of SUM149 and MDA-MB-231 cells by 40-47%, 57-60%, and 61.5-73%, respectively. Smart particles encapsulating the scrambled siRNA sequence did not affect RhoC protein expression or the invasion, motility, and migration of SUM149 and MDA-MB-231 cells, which indicate the biocompatibility of the polymeric carrier and selectivity of the observed RhoC knockdown. These results collectively indicate the therapeutic potential of smart anti-RhoC particles in arresting the metastatic spread of breast cancer cells.

Development of Spectrofluorimetric and HPLC Methods for In vitro Analysis of Repaglinide

Spectrofluorimetric and high-performance liquid chromatography methods for estimation of repaglinide were developed. These methods were validated for estimation of repaglinide in tablets as well as in receptor fluid obtained during in vitro permeation studies. Repaglinide was observed to exhibit emission and excitation wavelengths, respectively, at 379 nm and 282 nm with linearity in the concentration range of 5-80 µg/ml. High-performance liquid chromatography analysis of repaglinide yielded retention time of 6.14 min with linearity ranging from 0.1-1.2 µg/ml concentration. Spectrofluorimetric analysis of repaglinide in tablets yielded results comparable to high performance liquid chromatography.

Phosphorylation of Crk on tyrosine 251 in the RT loop of the SH3C domain promotes Abl kinase transactivation

Here, we report the identification and characterization of a novel tyrosine phosphorylation site in the carboxy-terminal Src Homology 3 (SH3) (SH3C) domain of the Crk adaptor protein. Y251 is located in the highly conserved RT loop structure of the SH3C, a region of Crk involved in the allosteric regulation of the Abl kinase. Exploiting kinase assays to show that Y251 is phosphorylated by Abl in vitro, we generated affinity-purified antisera against phosphorylated Y251 in Crk and showed that Abl induces phosphorylation at Y251 in vivo, and that the kinetics of phosphorylation at Y251 and the negative regulatory Y221 site in vitro are similar. Y251 on endogenous Crk was robustly phosphorylated in chronic myelogenous leukemia cell lines and in A431 and MDA-MB-468 cells stimulated with epidermal growth factor. Using streptavidin-biotin pull downs and unbiased high-throughput Src Homology 2 (SH2) profiling approaches, we found that a pY251 phosphopeptide binds specifically to a subset of SH2 domains, including Abl and Arg SH2, and that binding of pY251 to Abl SH2 induces transactivation of Abl 1b. Finally, the Y251F Crk mutant significantly abrogates Abl transactivation in vitro and in vivo. These studies point to a yet unrealized positive regulatory role resulting from tyrosine phosphorylation of Crk, and identify a novel mechanism by which an adaptor protein activates a non-receptor tyrosine kinase by SH2 domain displacement.

Effect of different non-steroidal anti-inflammatory drugs, aspirin, nimesulide and celecoxib on the disaccharide hydrolases and histoarchitecture of the rat intestinal brush border membrane

Non-steroidal anti-inflammatory drugs (NSAIDs) are known to cause gastrointestinal damage. New anti-inflammatory drugs have been developed in an attempt to improve their gastrointestinal side effect profile which however failed to do so. Therefore, the objective of the present study was to compare the effect of three different NSAIDs, aspirin, nimesulide and celecoxib on the intestinal brush border membrane (BBM) marker enzymes and correlate these alterations to the histoarchitecture of the intestine using electron microscopic study. Female Wistar rats were divided into four different groups viz: Group I (Control), Group II (aspirin treated), Group III (nimesulide treated) and Group IV (celecoxib treated). The Group II, III and IV received the corresponding drugs dissolved in water orally at a dose of 40 mg/kg body weight, while the control received the vehicle only. After 28 days, all the treatment groups demonstrated significant alterations in the activities of intestinal disaccharide hydrolases and alkaline phosphatase in both the crude homogenates and BBM preparations as well. The histopathological observations also showed considerable changes in the intestinal mucosa. It was suggested that NSAIDs like aspirin, nimesulide and celecoxib pose intestinal side effects due to initial changes in the enzymatic composition of the intestinal apical membranes. It was further concluded that newly discovered NSAIDs such as celecoxib has better safety profiles but studies are still required to comment decisively on the suitability of various NSAIDs depending upon their cyclooxygenase enzyme specificity.

Do food stamps cause obesity? Evidence from immigrant experience

I use changes in immigrant eligibility for food stamps under the 1996 federal law and heterogeneous state responses to set up a natural experiment research design to study the effect of food stamps on Body Mass Index (BMI) of adults in immigrant families. I find that in the post-1996 period food stamps use by foreign-born unmarried mothers with a high school or lower education was 10 percentage points higher in states with substitute programs than in states that implemented the federal ban. However, this increase in FSP participation was not associated with any statistically significant difference in BMI. I find that FSP participation was associated a statistically insignificant 0.3% increase in BMI among low-educated unmarried mothers.

In vitro clonal multiplication of an apple rootstock by culture of shoot apices and axillary buds

In vitro clonal multiplication of apple rootstock MM 111 using axillary buds and shoot apices were carried out. Vegetative axillary buds of the size of 0.2-2.0 cm and shoot apices measuring 4 mm in length were initiated to shoot proliferation on MS medium supplemented with BA (0.5 - 1.0 mgl(-1)), GA3(0.5 mgl(-1)), with or without IBA(0.05 - 0.1 mgl(-1)). Small size explants showed less phenol exudation and less contamination. Following establishment phase, the small shoots emerged from explants were subcultured on MS medium supplemented with different combinations and concentrations of growth regulators. BA (1.0 mgl(-1)) and GA3 (0.5 mgl(-1)) combination showed highest multiplication rate (1:5), andcl also produced longer shoots. Two step rooting was done by transferring microcuttings to auxin free solid medium after root initiation in dark on 1/2 strength MS liquid medium containing IBA (0.5 mgl(-1) ). Rooted plantlets were transferred to peat containing paper cups and resulting plants of MM 111 acclimated successfully for transfer to field.

Maternal CA-125 levels in pregnancy and the puerperium

OBJECTIVE

To determine the levels of CA-125 throughout pregnancy and the puerperium to establish a baseline, thereby indicating what values may be indicative of the pathologic conditions usually associated with elevated CA-125 levels.

STUDY DESIGN

A prospective, longitudinal study was carried out on a consecutive series of pregnant women to determine their CA-125 levels throughout pregnancy and during the puerperium. Blood was drawn at four- to six-week intervals for clinically indicated tests. The residual sera were kept frozen, and subsequently CA-125 measurements were determined by radioimmunoassay.

RESULTS

Of 34 women enrolled in the study, 20 completed the evaluations throughout pregnancy and in the puerperium. The remaining 14 had evaluations for varying portions of their pregnancies but not throughout pregnancy or during the puerperium. The results in these two groups were compared and found not to be statistically significantly different. For the group as a whole, the levels of CA-125 were high, with wide fluctuations in the first trimester; the levels in the early first trimester (five to eight weeks) were particularly high, with a mean of 55.8 and median of 36.2 (range, 6.9-251.2) U/mL. The levels then dropped and remained < 35 U/mL through the rest of pregnancy (including immediately prior to delivery). Another peak, with wide fluctuations, occurred soon after delivery, with a mean of 39.8 and median of 41.9 (range, 10.7-296.7) U/mL. In the late postpartum period (2-10 weeks after delivery) there was a return to baseline levels in all subjects.

CONCLUSION

This study showed that there is a distinct pattern in CA-125 levels during pregnancy and the puerperium. Due to the wide fluctuations in CA-125 levels in very early pregnancy and the immediate postpartum period, CA-125 values during these periods are not useful for clinical correlation with the pathologic conditions known to be associated with elevated levels of CA-125. However, further study is needed to determine whether extreme values in the first trimester or elevated levels after the first trimester are diagnostic or predictive of any conditions related to pregnancy.

Effect of graded head-up tilt on parasympathetic reactivity

Thirteen healthy subjects were tested for parasympathetic reactivity during head-up tilt and reversal of the tilt. Head-up tilt (70 degrees) resulted in significant increase in baseline heart rate and diastolic blood pressure. Head-up tilt also led to increased parasympathetic reactivity as measured by Valsalva manoeuvre and hand grip test. Heart rate response to deep breathing test did not change. The reversal of the tilt led to returning of heart responses to original values. Responses indicate towards enhanced parasympathetic reactivity during head-up tilt position.

Effect of lead acetate administration on ATPases of brain and its mitochondrial and synaptosomal fractions in adult mice

The effects of oral administration of lead acetate on the activities of cation-transport ATPases and on the brain and its mitochondrial and synaptosomal fractions of male mice were studied at doses of 1, 5, and 20 mg lead acetate per 100 g body weight per day for 4, 8, 12, and 16 weeks. The activities of Na(+)-ATPase, K(+)-ATPase, total-ATPase, and Na(+)-K(+)-ATPase decreased significantly at doses of 1 and 5 mg lead acetate after 12 and 16 weeks of treatment; changes in the activities were not marked after 4 and 8 weeks of lead administration. However, the 20-mg dose significantly reduced enzyme activities at all treatment intervals.