Catalogue Search | MBRL
Search Results Heading
Explore the vast range of titles available.
MBRLSearchResults
-
DisciplineDiscipline
-
Is Peer ReviewedIs Peer Reviewed
-
Item TypeItem Type
-
SubjectSubject
-
YearFrom:-To:
-
More FiltersMore FiltersSourceLanguage
Done
Filters
Reset
39
result(s) for
"Ramzan, Rabia"
Sort by:
Stress-mediated generation of deleterious ROS in healthy individuals - role of cytochrome c oxidase
by
Ramzan Rabia
,
Kadenbach Bernhard
,
Vogt, Sebastian
in
Allosteric properties
,
Apoptosis
,
Calcium
2020
Psychosocial stress is known to cause an increased incidence of coronary heart disease. In addition, multiple other diseases like cancer and diabetes mellitus have been related to stress and are mainly based on excessive formation of reactive oxygen species (ROS) in mitochondria. The molecular interactions between stress and ROS, however, are still unknown. Here we describe the missing molecular link between stress and an increased cellular ROS, based on the regulation of cytochrome c oxidase (COX). In normal healthy cells, the “allosteric ATP inhibition of COX” decreases the oxygen uptake of mitochondria at high ATP/ADP ratios and keeps the mitochondrial membrane potential (ΔΨm) low. Above ΔΨm values of 140 mV, the production of ROS in mitochondria increases exponentially. Stress signals like hypoxia, stress hormones, and high glutamate or glucose in neurons increase the cytosolic Ca2+ concentration which activates a mitochondrial phosphatase that dephosphorylates COX. This dephosphorylated COX exhibits no allosteric ATP inhibition; consequently, an increase of ΔΨm and ROS formation takes place. The excess production of mitochondrial ROS causes apoptosis or multiple diseases.
Journal Article
Multiple Mechanisms Regulate Eukaryotic Cytochrome C Oxidase
by
Kadenbach, Bernhard
,
Vogt, Sebastian
,
Ramzan, Rabia
in
adenine nucleotides
,
Adenosine triphosphate
,
Allosteric properties
2021
Cytochrome c oxidase (COX), the rate-limiting enzyme of mitochondrial respiration, is regulated by various mechanisms. Its regulation by ATP (adenosine triphosphate) appears of particular importance, since it evolved early during evolution and is still found in cyanobacteria, but not in other bacteria. Therefore the “allosteric ATP inhibition of COX” is described here in more detail. Most regulatory properties of COX are related to “supernumerary” subunits, which are largely absent in bacterial COX. The “allosteric ATP inhibition of COX” was also recently described in intact isolated rat heart mitochondria.
Journal Article
Assessment of the Antimicrobial Potentiality and Functionality of Lactobacillus plantarum Strains Isolated from the Conventional Inner Mongolian Fermented Cheese Against Foodborne Pathogens
by
Abdelazez, Amro
,
Amjad, Adnan
,
Afzaal, Muhammad
in
Acid production
,
Acids
,
anti-infective agents
2019
Lactobacillus plantarum are amongst the diversified lactic acid bacteria (LAB) species which are being utilized abundantly in the food industry. Numerous L. plantarum strains have been reported to produce several antimicrobial compounds. Diacetyl, hydrogen peroxide, organic acids, as well as bacteriocins can also be exemplified by a variable spectrum of actions. The current study was intended to conduct the screening and characterization of antimicrobial prospective of L. plantarum from traditional Inner Mongolian fermented hard cheese. Foodborne pathogens, Salmonella typhimurium, Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus, were examined by using the Oxford cup technique and the mixed culture inhibition assays. The resulting analyses disclosed that L. plantarum KLDS1.0344 indicated broad antimicrobial spectrum against all selected pathogens as compared to other LAB used in this study. Additionally, the decrement of the pathogen population was observed up to 3.47 logs in mixed culture inhibition assays. L. plantarum KLDS 1.0344 acid production was recorded up to 71.8 ± 3.59 °D in mixed culture while antimicrobial particles released in cell free supernatants demonstrated bacteriocin-like characteristics showing substantial pH stability (2.0–6.0), proteolytic enzyme reduced the antibacterial activity (15.2 ± 0.6 mm–20.4 ± 0.8 mm), heat stability (20 min at 120 °C) against selected pathogens. Moreover, the spectrum range of antimicrobial peptides after the partial purification was decreased as compared to the crude bacteriocin-like compound. The SDS-PAGE analysis showed the molecular weight range of partially purified bacteriocin from 12 to 45 kDa. After analyzing the obtained data from the current experimentation showed that the capability of L. plantarum KLDS 1.0344 to oppose the pathogen growth in vitro relies on the occurrence of organic acids along with bacteriocin-like compounds proving L. plantarum KLDS 1.0344 as a potentially appropriate candidate as an alternative bio-control agent against foodborne pathogens.
Journal Article
Topography of the Papillary Muscles in the Mitral Valve Complex and Their Relevance for Mitral Valve Function
by
Figiel, Jens
,
Van Laethem, Alina-Jutta
,
Rastan, Ardawan J.
in
Angina pectoris
,
Atrial fibrillation
,
Cardiac arrhythmia
2025
Background: The mitral valve apparatus is a complex system that requires sufficient function of all involved structures. Previous studies have demonstrated that ventricular remodeling can cause displacement of subannular structures, including the papillary muscles, which in turn promotes the development of mitral regurgitation. Furthermore, in such cases, annuloplasty alone is often insufficient to restore optimal valve function. Instead, additional reconstruction of the subannular apparatus is associated with improved clinical outcomes. Our study aimed to analyze the topography of the papillary muscles in the mitral valve complex and their relevance for mitral valve function. Methods: In 148 patients who underwent both cardiac computed tomography (CT) and echocardiography, the position of the papillary muscles within the left ventricle was assessed. CT scans were evaluated in end-diastolic four-chamber view, two-chamber view, and short-axis view. CT analysis involved determining the position of the papillary muscles based on a modified left ventricular segmentation scheme, which subdivided the original segments into “a” and “b” subsegments in a counterclockwise manner. Furthermore, the midventricular diameter, ventricular length, as well as the angle between the papillary muscle (PM) and the left ventricular wall, were measured. Comorbidities were assessed. The presence of mitral regurgitation (MR) and ejection fraction was determined based on echocardiographic data. Echocardiography was conducted either as part of initial cardiological assessments or during follow-up examinations. For detailed statistical analysis, the patients were divided into the following groups: control group, MR-only group, coronary heart disease (CHD)-only group, and combined CHD and MR subgroup. Results: Mitral regurgitation was significantly correlated with age (p < 0.001) and hypertension (r = 0.1900, p = 0.0208), and in the MR-only subgroup, additionally with atrial fibrillation (r = 0.2426, p = 0.0462). The length (p < 0.001) and internal diameter (p < 0.001) of the left ventricle were significantly larger in men than in women. Different positions of the papillary muscles were identified. Segment 7a was significantly correlated with MR in the combined CHD and MR subgroup. In normal-sized ventricles, patients with MR and papillary muscle in 12a (p = 0.0095) or 10a (p = 0.0460) showed a significantly larger angle than patients without MR (overall dataset). Conclusions: Assessment of papillary muscle position is essential in diagnosing mitral regurgitation and should guide the consideration of subannular repair during surgical treatment.
Journal Article
Implicating Ultrasonication and Heat–Moisture Treatments as a Green and Eco-Friendly Approach for Dual Physical Modification of Eleocharis tuberosa Starch to Improve Its Physico-Chemical and Functional Properties
2025
Dual-physical modification is an eco-friendly and waste-free approach for enhancing the functionality of native starches compared with a single modification. In the present study, the individual and combined interrelating effects of hydrothermal (heat moisture (HM) with 15%, 20%, and 25% moisture) and non-thermal (ultrasonication (US) with 200, 400, and 600 power (W)) on the physical modification of Eleocharis tuberosa (Chinese water chestnut (CWCS)) starch were studied. Furthermore, their effects on the morphology, FTIR, XRD, crystallinity, thermal, pasting, swelling power, solubility, rheological characteristics, and in vitro digestibility of native and modified starches were investigated. The results indicated a consistent B-type structure of CWCS, with a significant decrease in the crystallinity (22.32 ± 0.04–28.76 ± 0.02%), which was linked with ΔH (19.65 ± 0.01–12.18 ± 0.06 Jg−1) and amylose content (34.67 ± 0.07–40.73 ± 0.11%). The absorbance ratio 1048/1025 specified that the combination of HM-US compacted the short-range order degree up to 1.30 for HM25–US600-CWCS. The starch treated with HM, followed by the US, considerably amplified the setback, peak, and final viscosities compared with the HM-treated starch. The rheological analysis demonstrated that the fluidity of CWCS was enhanced (G′ > G″, tan δ < 1) by the synergistic effect of HM and US, increasing the resistivity toward deformation during paste development. The dual-modified starch exhibited a slower glucose release rate with increasing moisture (25%) during HM and 600 W during the US, with higher RS contents of 45.83 ± 0.28% and 43.09 ± 0.12%, respectively. Dual-physical modification exhibited a significant aptitude for modifying native starches structurally and functionally as a substitute for product formulation with a low glycemic index.
Journal Article
Cytochrome c Oxidase Inhibition by ATP Decreases Mitochondrial ROS Production
by
Dolga, Amalia M.
,
Michels, Susanne
,
Rastan, Ardawan J.
in
Adenosine Diphosphate - metabolism
,
Adenosine Triphosphate - metabolism
,
Allosteric properties
2022
This study addresses the eventual consequence of cytochrome c oxidase (CytOx) inhibition by ATP at high ATP/ADP ratio in isolated rat heart mitochondria. Earlier, it has been demonstrated that the mechanism of allosteric ATP inhibition of CytOx is one of the key regulations of mitochondrial functions. It is relevant that aiming to maintain a high ATP/ADP ratio for the measurement of CytOx activity effectuating the enzymatic inhibition as well as mitochondrial respiration, optimal concentration of mitochondria is critically important. Likewise, only at this concentration, were the differences in ΔΨm and ROS concentrations measured under various conditions significant. Moreover, when CytOx activity was inhibited in the presence of ATP, mitochondrial respiration and ΔΨm both remained static, while the ROS production was markedly decreased. Consubstantial results were found when the electron transport chain was inhibited by antimycin A, letting only CytOx remain functional to support the energy production. This seems to corroborate that the decrease in mitochondrial ROS production is solely the effect of ATP binding to CytOx which results in static respiration as well as membrane potential.
Journal Article
Enhanced Bioaccessibility of Microencapsulated Puerarin Delivered by Pickering Emulsions Stabilized with OSA-Modified Hydrolyzed Pueraria montana Starch: In Vitro Release, Storage Stability, and Physicochemical Properties
2022
Puerarin is a bioactive flavonoid isolated from Kudzu roots that possesses numerous health benefits. However, its poor bioavailability and existing complex delivery systems with safety issues are challenging tasks for its incorporation into functional foods. Preparing modified-starch-stabilized Pickering emulsions containing microencapsulated puerarin with improved bioaccessibility was the key objective of the present research work. Acid-hydrolyzed high-amylose Pueraria montana starch (PMS) was modified with octenyl succinic anhydride (OSA) and evaluated as an emulsifier to prepare emulsions. The FTIR, SEM, and XRD results showed that PMS was successfully modified. Furthermore, the emulsification index (EI), mean droplet size, and ζ-potential values showed that modified starch with a higher degree of substitution (DS) enhanced the storage stability of emulsions. Similarly, the retention degree and encapsulation efficiency results of puerarin proved the assumption after storage of 16 d. The Pickering emulsions also helped in the controlled release of microencapsulated puerarin in vitro. The study outcomes proved that Pickering emulsions stabilized with OSA-modified PMS have promising applicability in functional foods as efficient food-grade delivery systems, enhancing oral supplementation and accessibility of puerarin.
Journal Article
Assessment of In Vitro and In Vivo Bioremediation Potentials of Orally Supplemented Free and Microencapsulated Lactobacillus acidophilus KLDS Strains to Mitigate the Chronic Lead Toxicity
by
Dong, Lihong
,
Gul, Mehak
,
Zhao, Dong
in
Antioxidants
,
Bacteria
,
Bioengineering and Biotechnology
2021
Lead (Pb) is a pestilent and relatively nonbiodegradable heavy metal, which causes severe health effects by inducing inflammation and oxidative stress in animal and human tissues. This is because of its significant tolerance and capability to bind Pb (430 mg/L) and thermodynamic fitness to sequester Pb in the Freundlich model ( R 2 = 0.98421) in vitro . Lactobacillus acidophilus KLDS1.1003 was selected for further in vivo study both in free and maize resistant starch (MRS)–based microencapsulated forms to assess its bioremediation aptitude against chronic Pb lethality using adult female BALB/c mice as a model animal. Orally administered free and microencapsulated KLDS 1.1003 provided significant protection by reducing Pb levels in the blood (127.92 ± 5.220 and 101.47 ± 4.142 µg/L), kidneys (19.86 ± 0.810 and 18.02 ± 0.735 µg/g), and liver (7.27 ± 0.296 and 6.42 ± 0.262 µg/g). MRS-microencapsulated KLDS 1.0344 improved the antioxidant index and inhibited changes in blood and serum enzyme concentrations and relieved the Pb-induced renal and hepatic pathological damages. SEM and EDS microscopy showed that the Pb covered the surfaces of cells and was chiefly bound due to the involvement of the carbon and oxygen elements. Similarly, FTIR showed that the amino, amide, phosphoryl, carboxyl, and hydroxyl functional groups of bacteria and MRS were mainly involved in Pb biosorption. Based on these findings, free and microencapsulated L. acidophilus KLDS 1.0344 could be considered a potential dietetic stratagem in alleviating chronic Pb toxicity.
Journal Article
Cholate Disrupts Regulatory Functions of Cytochrome c Oxidase
by
Napiwotzki, Jörg
,
Weber, Petra
,
Kadenbach, Bernhard
in
Adenosine Diphosphate - pharmacology
,
allosteric ATP-Inhibition
,
Allosteric properties
2021
Cytochrome c oxidase (CytOx), the oxygen-accepting and rate-limiting enzyme of mitochondrial respiration, binds with 10 molecules of ADP, 7 of which are exchanged by ATP at high ATP/ADP-ratios. These bound ATP and ADP can be exchanged by cholate, which is generally used for the purification of CytOx. Many crystal structures of isolated CytOx were performed with the enzyme isolated from mitochondria using sodium cholate as a detergent. Cholate, however, dimerizes the enzyme isolated in non-ionic detergents and induces a structural change as evident from a spectral change. Consequently, it turns off the “allosteric ATP-inhibition of CytOx”, which is reversibly switched on under relaxed conditions via cAMP-dependent phosphorylation and keeps the membrane potential and ROS formation in mitochondria at low levels. This cholate effect gives an insight into the structural-functional relationship of the enzyme with respect to ATP inhibition and its role in mitochondrial respiration and energy production.
Journal Article
The Role of Matrix Metalloproteinases in Thoracic Aortic Disease: Are They Indicators for the Pathogenesis of Dissections?
2024
The pathogenesis of aortic aneurysm and dissection continues to be under discussion. Extracellular matrix (ECM) remodeling processes in the aortic wall are hypothesized to be involved in the development of the disorders. Therefore, in a histological study, we investigated the expression of metalloproteases 1 and 9 (MMP1 and MMP9) and their inhibitors (TIMP 1 and TIMP 2) in cardiac surgery patients. In parallel, we studied the aortic roots by echocardiography. Clinical reports of 111 patients (30 women and 81 men) who suffered from aortic aneurysms and aortic dissection were evaluated and studied by transesophageal echocardiography. Seven patients who had coronary heart disease served as “healthy controls”. All patients underwent the necessary surgical procedure according to the diagnosed aortic disease in the period from 2007 to 2015. A tissue sample of the aortic biopsies was collected from each patient during surgery. Immunohistochemical staining was performed for MMP1 and MMP9 and TIMP1 and TIMP2 as well. Vascularization was monitored by a CD 31 antibody. In direct comparison, the expressions are not homogeneous. We found the smallest changes in the intima area at all. TIMP 1 and TIMP 2 distribution increases from the lumen of the vessel outward in the wall layers of the aorta. In the case of arteriosclerotic changes, intima had a capillarization, but not in the media. An opposite pattern was found in the dissected aortas. There are differences in the vascularization between the aneurysm and dissection and the different layers, respectively. A different remodeling process of the ECM in comparison to the vascular layers must be hypothesized. Reading the patterns of staining and with regard to the known inhibitory effect of MMP9 on ECM remodeling, but especially TIMP 2 on neoangiogenesis, disturbed nutrition, and dysfunctional vasa vasorum remodeling must be assumed as causes of dissection.
Journal Article