Soheila Mohammadi

Objective (s): Attitude toward fertility and childbearing play an important role in reproductive behavior. This study aimed to assess attitudes toward fertility and childbearing and to identify associated factors among female teachers in Kermanshah, Iran. Methods: This cross-sectional study included 171 married female teachers of reproductive age in Kermanshah. Participants ...

Caspase-9 is crucial for initiating apoptosis, and its activity is tightly regulated through various mechanisms, especially phosphorylation by kinases activated by extracellular growth factors, osmotic stress, or during mitosis. Mass spectrometric analyses have shown that residues S302 and S307 in human caspase-9 are prone to phosphorylation. To investigate the effects of phosphorylation at these sites, three phosphomimetic variants of recombinant caspase-9 were created: S302D, S307D, and the combined S302D/S307D variant. The QuickChange method was employed to generate these mutant constructs, which were expressed in Escherichia coli (E. coli) and purified using affinity chromatography. For enzymatic assays, the chromogenic substrate Ac-LEHD-pNA was utilized, and the temperature profiles of enzyme activity were assessed. Computational modeling was used to predict the structures of the mutants, allowing for comparison with the native enzyme. The results indicated that both the S302D and S302D/S307D variants exhibited complete loss of enzyme activity. In contrast, the S307D variant demonstrated a 10-fold increase in the Michaelis constant (K_m) for the substrate and a 4-fold increase in the maximum reaction rate (V_max) compared to the wild-type enzyme. Notably, the k_cat/K_m value for wild-type caspase-9 was three times greater than that of the S307D variant. The optimal temperature for wild-type activity was between 30 and 37 °C, while for the S307D variant, it ranged from 37 to 45 °C. Importantly, the S302 residue is essential for caspase-9 function; introducing a negative charge at this position leads to complete inactivation of the enzyme.

Background and Aim: Caspase-9 is a key enzyme in the intrinsic pathway of apoptosis that its activity is regulated by various mechanisms such as phosphorylation. It has been reported that phosphorylation of serine 310 in murine caspase-9 prevents enzyme processing. The role of this residue in human caspase-9 activity in not ...

One of the major reasons for mortality throughout the world is cardiovascular diseases. Therefore, bio-markers of cardiovascular disease are of high importance to diagnose and manage procedure. Detecting biomarkers provided a promising procedure in developing bio-sensors. Fast, selective, portable, accurate, inexpensive, and sensitive biomarker sensing instruments will be necessary for detecting and predicting diseases. One of the cardiac biomarkers may be ordered as C-reactive proteins, lipoprotein-linked phospho-lipase, troponin I or T, myoglobin, interleukin-6, interleukin-1, tumor necrosis factor alpha, LDL and myeloperoxidase. The biomarkers are applied to anticipate cardio-vascular illnesses. Initial diagnoses of these diseases are possible by several techniques; however, they are laborious and need costly apparatus. Current researches designed various bio-sensors for resolving the respective issues. Electrochemical instruments and the proposed bio-sensors are preferred over other methods due to its inexpensiveness, mobility, reliability, repeatability. The present review comprehensively dealt with detecting biomarkers of cardiovascular disease through electro-chemical techniques.

The aggregation of alpha-synuclein (αS), natively unstructured presynaptic protein, is a crucial factor leading to the pathogenesis of Parkinson’s disease (PD) and other related disorders. Recent studies have shown prefibrillar and oligomeric intermediates of αS as toxic to the cells. Herein, split-luciferase complementation assay is used to design a “signal-on” biosensor to monitor oligomerization of A53T αS inside the cells. Then, the effect of carbon-based nanomaterials, such as graphene quantum dots (GQDs) and graphene oxide quantum dots (GOQDs), on A53T αS oligomerization in vitro and in living cells is investigated. In this work, for the first time, it was found that GQDs at a concentration of 0.5 µg/mL can promote A53T αS aggregation by shortening the nucleation process, which is the key rate-determining step of fibrillation, thereby making a signal-on biosensor. While these nanomaterials may cross the blood–brain barrier because of their small sizes, the interaction between αS and GQDs may contribute to PD etiology.

Background: Parkinson's disease (PD) primarily results from a severe and selective damage of dopaminergic neurons. The neuropathological hallmark of the disease is the presence of protein inclusions of α-Synuclein (αS) within the surviving neurons. To date, several researchers have been focused on screening for the inhibitors that are able to block, slow down, or reverse αS aggregation, particularly at its early stages. Objectives: In this work, we aimed to investigate the effects of a β-Synuclein derived peptide on oligomerization of pathological mutants of αS (A53T, A30P, E46K). Method: The effects of the peptide on aggregation of native and mutant of αS were examined by fluorescence spectroscopy and electron microscopy. The influence of the peptide inhibitor on cell toxicity of aggregation products of αS and its mutants were investigated by MTT assay and flow cytometry. Results: It was shown that the peptide inhibitor effectively blocks the fibrillation of not only the native αS but also the PD related αS mutants in vitro, suggesting a similar mechanism of oligomerization for native and mutants of αS. The peptide inhibitor greatly diminished the cell toxicity of the aggregation products of native and mutants of αS. Conclusion: Our findings suggest the therapeutic potential of this peptide for treatment of the rare inherited forms of PD.

Background: In recent years, nanomaterials have been widely used in large quantities which make people be more frequently exposed to the chemically synthesized nanoparticles (NPs). When NPs are introduced into an organism, they may interact with a variety of cellular components with yet largely unknown pathological consequences. Objective: It was found that NPs enhance the rate of protein fibrillation in the brain by decreasing the lag time for nucleation. Protein fibrillation is implicated in the pathogenesis of the several neurodegenerative diseases such as Parkinson’s disease (PD). α-Synuclein (αS) is natively an unfolded protein which is involved in the pathogenesis of PD. In the present study, we have analyzed the effects of three different NPs on αS fibrillation. Materials and Methods: αS protein expression and purification was done and fibrils formation was induced in the absence or presence of the three types of NPs (i. e., TiO2, SiO2, and SnO2). The enhancement of the fluorescence emission of Thioflavin T (ThT) and transmission electron microscopy (TEM) were used to monitor the appearance and growth of the fibrils. The adsorption of αS monomers on the surface of NPs was investigated by tyrosine fluorescence emission measurements. Results: We found that TiO2-NPs enhances αS fibril formation even at a concentration of 5 µg.mL-1, while the two other NPs show no significant effect on the kinetics of the fibrillation. Intrinsic tyrosine emission measurement has confirmed that the TiO2-NPs interact with αS fibrillation products. It is suggested that TiO2-NPs may enhance the nucleation of αS protein that leads to protein fibril formation. Conclusion: The fibrillization process of αS protein is profoundly affected by the presence of TiO2-NPs. This finding unveils the neurotoxicity potential of the TiO2-NPs, which may be considered as a probable risk for PD.

A simple and rapid method using coupled bioluminescent assay was developed to determine level of ADP. ADP is involved in many biological reactions and ADP assay can be used for assaying some reactions universally by monitoring ADP formation or depletion. ADP analysis involves incubation of ADP or extracts containing ADP with pyruvate kinase (PK) and PEP. The ATP formed by this reaction is determined by measuring the intensity of the initial light flash produced when luciferin‐luciferase preparation injected into the reaction mixture. In regard to the main role of the PK in this assay, the gene of PK from a Geobacillus species has been cloned in expression vector pET28a (+), sequenced and overexpressed in Escherichia coli. Recombinant protein was purified using Ni‐NTA column and then the purified PK was used in a coupled bioluminescent assay for ADP measurement. Kinetic properties of PK are determined according to a bioluminescent assay using firefly luciferase.