Secondary structure induction in aqueous vs membrane-like environments

The conformational propensity of the 20 naturally occurring amino acids was determined in aqueous 3-[N-morpholino]propane-sulfonic acid (MOPS) buffer, protein interior-like [nonmicellar sodium dodecylsulfate (SDS)] and membrane-like environments (micellar SDS and lysophosphatidylglycerol/lysophosphatidylcholine micelles) using a single “guest” position in a polyalanine-based model host peptide (Ac-KYA₁₃K-NH₂). This model system allows the intrinsic α-helical or β-sheet propensity of the amino acids to be determined without intra- and interchain side chain interactions. The overall environment dependence observed for the conformational propensity for the amino acids studied confirms the importance of determining propensity in lipidic environments to better elucidate the biological functions of proteins. The hydrophobic interactions between peptide side chains and lipids appeared to be the primary forces driving the conformational induction in lipidic environments of the model peptides studied. Finally, when comparing the results of these studies with those reported in the literature, the local environment was found to highly influence 65% of the 20 naturally occurring amino acids. © 1997 John Wiley & Sons, Inc. Biopoly 42: 489–498, 1997     

Cytokine single nucleotide polymorphisms in Iranian patients with pulmonary tuberculosis

BACKGROUND: Several genes coding for different cytokines may affect host susceptibility to tuberculosis. METHODS: In the present study, the allele and genotype frequencies of a number polymorphic genes coding for cytokines or cytokine receptors were investigated in Iranian patients with pulmonary tuberculosis (PTB). RESULTS: From the IL-1 cluster, a positive, significant difference was found at position -889, where the T/T genotype was over represented in PTB patients (p = 0.01); a positive, significant increase was found in the IL1R PstI 1970 C/C genotype, where the C allele was over represented in the PTB patients (p = 0.01). A significant negative association at codon 10 TGF-beta, T allele, was shown in our patients and the C allele and C/C genotype were over represented in the PTB patients (P<0.005). For TNF-alpha at position -238, we found a negative association for the G/A genotype and a positive association for the G/G genotype (p = 0.0009). Significant negative associations at position -590 IL-4, T allele and the T/T genotype were shown in our patients (p = 0.0007); also, the C allele and T/C genotype were significantly increased in our patients (P<0.05). With IL-6 at -174, G/G increased and G/C decreased significantly in the patients (P<0.005). CONCLUSION: Pro-inflammatory cytokines such as TNF-alpha and TGF-beta seem to be decreased, and IL-6 increased in PTB patients.     

In vitro culture response of apical and axillary shoot-tips excised from crisphead lettuce cores depends on head maturity, not storage time

Summary Successful lettuce (Lactuca sativa L.) breeding requires assessment, selection, and reseue of germplasm from field-grown plants during a limited period of time. Tissue culture methods have proved successful in rescuing selected lettuce genotypes and producing seeds in a disease-free environment. The present study was conducted to determine the response of the apical and axillary shoot-tips of lettuce to storage duration prior to in vitro culture. The study focused on core length as a source of variation between maternal explants. Advanced maturity was obtained by applying an agrotextile row cover over lettuce plants. Apical and axillary buds were derived from covered lettuce with long cores (46±0.8 mm) and from non-covered lettuce with short cores (30±0.7 mm). The cores were stored at 2°C for 0,2, or 13d. Apical and axillary shoot-tips were removed from the cores and placed onto MS medium. After 3 mo. of growth culture, twice as many leaf primordia (6.6 leaves) developed from the apical shoot-tip as compared to those from the axillary shoot-tip (3.0 leaves). More shoot-tips survived when excised from short cores (83%) than when excised from long cores (71%). Root formation was affected by the source of shoot-tip and the size of donor explant. Three times more explants from apical shoot-tips and short cores rooted (71%) than did explants from apical shoot-tips and long cores (27%) or explants from axillary shoot-tips (long cores, 14%; short cores, 19%). Storage of cores for up to 13 d had no effect on the survival rate of shoot-tips, nor on shoot or root formation, suggesting that cores of lettuce plants can be stored prior to in vitro micropropagation without significant loss of regeneration efficiency.     

Effect of tissue-harvesting site on yield of stem cells derived from adipose tissue: implications for cell-based therapies

The stromal vascular fraction (SVF) of adipose tissue contains an abundant population of multipotent adipose-tissue-derived stem cells (ASCs) that possess the capacity to differentiate into cells of the mesodermal lineage in vitro. For cell-based therapies, an advantageous approach would be to harvest these SVF cells and give them back to the patient within a single surgical procedure, thereby avoiding lengthy and costly in vitro culturing steps. However, this requires SVF-isolates to contain sufficient ASCs capable of differentiating into the desired cell lineage. We have investigated whether the yield and function of ASCs are affected by the anatomical sites most frequently used for harvesting adipose tissue: the abdomen and hip/thigh region. The frequency of ASCs in the SVF of adipose tissue from the abdomen and hip/thigh region was determined in limiting dilution and colony-forming unit (CFU) assays. The capacity of these ASCs to differentiate into the chondrogenic and osteogenic pathways was investigated by quantitative real-time polymerase chain reaction and (immuno)histochemistry. A significant difference (P = 0.0009) was seen in ASC frequency but not in the absolute number of nucleated cells between adipose tissue harvested from the abdomen (5.1 ± 1.1%, mean ± SEM) and hip/thigh region (1.2 ± 0.7%). However, within the CFUs derived from both tissues, the frequency of CFUs having osteogenic differentiation potential was the same. When cultured, homogeneous cell populations were obtained with similar growth kinetics and phenotype. No differences were detected in differentiation capacity between ASCs from both tissue-harvesting sites. We conclude that the yield of ASCs, but not the total amount of nucleated cells per volume or the ASC proliferation and differentiation capacities, are dependent on the tissue-harvesting site. The abdomen seems to be preferable to the hip/thigh region for harvesting adipose tissue, in particular when considering SVF cells for stem-cell-based therapies in one-step surgical procedures for skeletal tissue engineering.     

Electrochemical-based biosensors for detection of Mycobacterium tuberculosis and tuberculosis biomarkers

Abstract

Early detection of tuberculosis (TB) reduces the interval between infection and the beginning of treatment. However, commercially available tests cannot discriminate between BCG-vaccinated healthy persons and patients. Also, they are not suitable to be used for immunocompromised persons. In recent years, biosensors have attracted great attention due to their simple utility, accessibility, and real-time outputs. These sensors are increasingly being considered as pioneering tools for point-of-care diagnostics in communities with a high burden of TB and limited accessibility to reference laboratories. Among other types of biosensors, the electrochemical sensors have the advantages of low-cost operation, fast processing, simultaneous multi-analyte analyzing, operating with turbid samples, comparable sensitivity and readily available miniaturization. Electrochemical biosensors are sub-divided into several categories including: amperometric, impedimetric, potentiometric, and conductometric biosensors. The biorecognition element in electrochemical biosensors is usually based on antibodies (immunosensors), DNAs or PNAs (genosensors), and aptamers (aptasensors). In either case, whether an interaction of the antigen–antibody/aptamer or the hybridization of probe with target mycobacterial DNA is detected, a change in the electrical current occurs that is recorded and displayed as a plot. Therefore, impedimetric-based methods evaluate resistance to electron transfer toward an electrode by a Nyquist plot and amperometric/voltammetric-based methods weigh the electrical current by means of cyclic voltammetry, square wave voltammetry, and differential pulse voltammetry. Electrochemical biosensors provide a promising scope for the new era of diagnostics. As a consequence, they can improve detection of Mycobacterium tuberculosis traces even in attomolar scales.     

Identification of new S-RNase self-incompatibility alleles and characterization of natural mutations in Iranian almond cultivars

The two main objectives of this research were to identify new S-RNase alleles in Iranian almond cultivars and to characterize naturally occurring mutations in these alleles that may cause self-compatibility. We investigated S genotypes of 22 Iranian almond cultivars using stylar RNase electrophoresis, PCR and DNA sequencing. We report six previously unidentified P. dulcis S-RNase alleles (S ₄₅ , S ₄₆ , S ₄₇ , S ₄₈ , S ₄₉ and S ₅₀ ). Four of 12 tested S-RNases were found to be non-functional in vitro: S ₄₉ , S ₅₀ , S ₂₄ /S _na and S ₂₅ /S ₄₇ . Detected point mutations in the C3 coding region of S ₄₉ - and S ₅₀ -RNase, leading to the replacement of a highly conserved cysteine and histidine residues, are with the highest probability the reason of these S-RNases inactivity. Results also suggested that ten Iranian almond cultivars display unique S genotype. All presented data confirm Iranian cultivars as valuable almond sources which are of interest to almond breeding and conservation programs.     

Proteomics analysis of human brain tissue infected by street rabies virus

In order to extend the knowledge of rabies pathogenesis, a two-dimensional electrophoresis/mass spectrometry based postmortem comparative proteomics analysis was carried out on human brain samples. Alteration in expression profile of several proteins was detected. Proteins related to cytoskeleton, metabolism, proteasome and immune regulatory systems showed the most changes in expression levels. Among these groups, the cytoskeleton related proteins (dynein light chain, β-centractin, tubulin alpha-1C chain and destrin) and metabolism associated proteins (fatty acid-binding protein, macrophage migration inhibitory factor, glutamine synthetase and alpha enolase) were the main altered proteins. These alterations may be considered as an evidence of disturbances in neuronal key processes including axonal transport, synaptic activity, signaling and metabolic pathways in rabies virus infected human brain.     

HLA-DRBl and susceptibility to kidney allograft rejection in Southern Iranian patients

Kidney transplantation is the best treatment option for the patients with end-stage renal disease. Viral infections and genetic factors such as HLA-II antigens may affect the kidney transplant outcome. The compatibility of HLA-DRB1 molecules in the survival of kidney transplant is important. Also, the correlation between these molecules and viral infections is significant. The current study investigates the allele frequency of HLA-DRB1 in 41 recipient kidney transplant and 203 normal healthy controls by polymerase chain reaction using sequence specific primers. Moreover the relation between HLA-DRB1 allelic groups and hepatitis B, hepatitis C and cytomegalovirus viral infections was also studied. However statistical analysis of the allele frequencies didn’t show any significant association between HLA-DRB1 allelic group distributions or sharing and susceptibility to acute kidney transplant rejection (P > 0.05). Comparing the allele frequencies between HLA-DRB1*14 and DRB1*04 allelic showed a significant difference in controls and patients (P = 0.03 and P = 0.05 respectively). The results of the present study also showed a significant association between possession of HLA-DRB1*07 allele in kidney transplant recipients and hepatitis C virus infection (P = 0.009). In conclusion however the results of the present study did not showed relation between HLA-DRB1 allele’s frequencies or sharing and kidney transplantation outcome, the results indicated that HLA-DRB1 alleles may susceptible individuals to renal disease or play a role in susceptibility to viral infection in kidney transplant patients.