Plasma Membrane Ultrastructure Research Articles

The influence of dapagliflozin on cardiac remodeling, myocardial function and metabolomics in type 1 diabetes mellitus rats

BackgroundSodium-glucose cotransporter (SGLT)2 inhibitors have displayed beneficial effects on the cardiovascular system in diabetes mellitus (DM) patients. As most clinical trials were performed in Type 2 DM, their effects in Type 1 DM have not been established.ObjectiveTo evaluate the influence of long-term treatment with SGLT2 inhibitor dapagliflozin on cardiac remodeling, myocardial function, energy metabolism, and metabolomics in rats with Type 1 DM.MethodsMale Wistar rats were divided into groups: Control (C, n = 15); DM (n = 15); and DM treated with dapagliflozin (DM + DAPA, n = 15) for 30 weeks. DM was induced by streptozotocin. Dapagliflozin 5 mg/kg/day was added to chow. Statistical analysis: ANOVA and Tukey or Kruskal-Wallis and Dunn.ResultsDM + DAPA presented lower glycemia and higher body weight than DM. Echocardiogram showed DM with left atrium dilation and left ventricular (LV) hypertrophy, dilation, and systolic and diastolic dysfunction. In LV isolated papillary muscles, DM had reduced developed tension, +dT/dt and -dT/dt in basal condition and after inotropic stimulation. All functional changes were attenuated by dapagliflozin. Hexokinase (HK), phosphofructokinase (PFK) and pyruvate kinase (PK) activity was lower in DM than C, and PFK and PK activity higher in DM + DAPA than DM. Metabolomics revealed 21 and 5 metabolites positively regulated in DM vs. C and DM + DAPA vs. DM, respectively; 6 and 3 metabolites were negatively regulated in DM vs. C and DM + DAPA vs. DM, respectively. Five metabolites that participate in cell membrane ultrastructure were higher in DM than C. Metabolites levels of N-oleoyl glutamic acid, chlorocresol and N-oleoyl-L-serine were lower and phosphatidylethanolamine and ceramide higher in DM + DAPA than DM.ConclusionLong-term treatment with dapagliflozin attenuates cardiac remodeling, myocardial dysfunction, and contractile reserve impairment in Type 1 diabetic rats. The functional improvement is combined with restored pyruvate kinase and phosphofructokinase activity and attenuated metabolomics changes.

Combination of 1-methylcyclopropene and phytic acid inhibits surface browning and maintains texture and aroma of fresh-cut peaches

Surface browning, tissue softening, and aroma alteration are the primary quality deterioration in fresh-cut peaches. The visual appearance, textural attributes, antioxidant activity, and volatile compounds of fresh-cut peaches pre-treated with 1 μL L−1 of 1-methylcyclopropene (1-MCP) as whole fruit, and soaked in 0.05% of phytic acid (PA) for 3 min after cutting, alone or combined, were evaluated during cold storage at 0 ºC for 10 d. 1-MCP treatment of whole fruit showed minor effects on the textural attributes but restrained the production of reactive oxygen species of cut peaches. In contrast, PA treatment inhibited cut surface browning of fresh-cut peaches. The combined treatment synergistically promoted the total phenolic contents and antioxidant capacity, and inhibited the polyphenol oxidase (PPO) and peroxidase (POD) activities. The ultrastructure of cell wall and plasma membrane was maintained by the combined treatment, and the malondialdehyde (MDA) accumulation was restrained. E-nose and SPME GC-MS were used to assess the production of volatiles as influenced by 1-MCP and/or PA treatments. Results showed that the volatile aroma was improved by PA alone or in combination with 1-MCP especially on aldehydes, esters, and alcohols. Overall, PA mainly retarded the surface browning and improved the aroma quality of fresh-cut peaches, while 1-MCP combined with PA promoted the visual, textural, and aromatic qualities during the cold storage, suggesting the treatment can be used as a beneficial approach for the storage of fresh-cut peaches.

Mechanosurveillance: Tiptoeing T Cells.

Efficient scanning of tissue that T cells encounter during their migratory life is pivotal to protective adaptive immunity. In fact, T cells can detect even a single antigenic peptide/MHC complex (pMHC) among thousands of structurally similar yet non-stimulatory endogenous pMHCs on the surface of antigen-presenting cells (APCs) or target cells. Of note, the glycocalyx of target cells, being composed of proteoglycans and bulky proteins, is bound to affect and even modulate antigen recognition by posing as a physical barrier. T cell-resident microvilli are actin-rich membrane protrusions that puncture through such barriers and thereby actively place the considerably smaller T-cell antigen receptors (TCRs) in close enough proximity to APC-presented pMHCs so that productive interactions may occur efficiently yet under force. We here review our current understanding of how the plasticity of T-cell microvilli and physicochemical properties of the glycocalyx may affect early events in T-cell activation. We assess insights gained from studies on T-cell plasma membrane ultrastructure and provide an update on current efforts to integrate biophysical aspects such as the amplitude and directionality of TCR-imposed mechanical forces and the distribution and lateral mobility of plasma membrane-resident signaling molecules into a more comprehensive view on sensitized T-cell antigen recognition.

THE GROWTH AND CHROMIUM CONTENT OF BANANA PLANT (Musa acuminata) CV. AMBON LUMUT IN CHROMIUM STRESS CONDITION

The plants that live in polluted Chromium (Cr) areas can experience a variety of disorders in the body. The disruption caused by Cr can cause damage DNA, proteins, photosynthetic pigments, and chloroplast ultrastructure of cell membranes. It can inhibit germination, photosynthesis, respiration, cell division and growth, resulting in lower yields. To find out how Cr stress influences to banana plants {Musa acuminata) cv. Ambon Lumut, the present research was conducted on the growth and content of Cr in banana plants. In this research, bananas was grown in-vitro with Cr concentrations of 0, 50, 100, 200 and 400 ppm in the medium. The results showed that Cr influenced of the growth and content of Cr in banana plants {Musa acuminata) cv. Ambon Lumut. It is likely that the greater the concentration of Cr in the medium was, the smaller the increase in weight was. Root-shoot ratio and Cr content in root and shoot tends to be greater by increasing Cr concentration in the medium.

V\u03b39V\u03b42 T cells strengthen cisplatin inhibition activity against breast cancer MDA-MB-231 cells by disrupting mitochondrial function and cell ultrastructure

BackgroundBreast cancer ranks second of new cases and fifth of death in 2018 worldwide. Cis-platinum (CDDP) has been used as a chemotherapy to treat breast cancer for years. However, CDDP can adversely disrupt immune function of host. Thus, development of new protocol that can minimize side effect and meanwhile elevate clinical efficacy of CDDP will eventually benefit cancer patients. Since Vγ9Vδ2 T cells can up-regulate immune function of cancer patients, therefore, our hypothesis is that introduction of Vγ9Vδ2 T cells could potentiate CDDP efficacy against breast cancer.MethodsWe used breast cancer cell line MDA-MB-231 as model cell to test our hypothesis. The cancer cell viability in vitro in the context of different dose of CDDP was analyzed by flow cytometry. The cytoskeleton alteration was visualized by confocal microscopy, and the ultrastructure of cell membrane was observed by atomic force microscopy. The mitochondrial function of MDA-MB-231 cells was detected as well by flow cytometry.ResultsComparing to either Vγ9Vδ2 T cells or CDDP alone, Vγ9Vδ2 T cells plus CDDP could more strikingly induce MDA-MB-231 cell membrane ultrastructure disruption and cytoskeleton disorder, and more significantly enhance the inhibition of CDDP on proliferation of MDA-MB-231 cells. At the same time, Vγ9Vδ2 T cells strengthened CDDP-induced mitochondrial dysfunction of cancer cells.ConclusionThis work revealed that Vγ9Vδ2 T cells could synergistically enhance the inhibition activity of CDDP against breast cancer cells. Meanwhile, this in vitro proof-of-concept study implied the clinical prospect of the combining application of Vγ9Vδ2 T cells and CDDP in breast cancer therapy.

Parallel Acquisition of Plasma Membrane Ultrastructure and Cytosolic Protein Localisation in Cultured Cells via Correlated Immunogold SEM.

Scanning electron microscopy (SEM) takes advantage of distinct detectors to visualise secondary and back-scattering electrons. Here, we report an integrated approach that relies on these two detection methods to simultaneously acquire correlated information on plasma membrane topography and curvature-sensitive cytosolic protein localization in intact cell samples. We further provide detailed preparation and staining protocols, as well as a thorough example-based discussion for imaging optimisation. Collectively, the presented method enables rapid and precise analysis of cytosolic proteins adjacent to cellular membranes with a resolution of ~100 nm, without time-consuming preparations or errors induced by sequential visualisation present in fluorescence-based correlative approaches.

Selenium alleviated chromium stress in Chinese cabbage (Brassica campestris L. ssp. Pekinensis) by regulating root morphology and metal element uptake

Excessive chromium (Cr) causes toxicity to plants, while the beneficial effects of selenium (Se) have been verified in plants under various adverse conditions. Under Cr stress, the impacts of exogenous Se on root morphology and metal element uptake were investigated in root of Chinese cabbage by cellular and biochemical approaches. Exogenous Se alleviated Cr-induced irreversible damage to root morphology, plasma membrane integrity and ultrastructure of root tip cells. Compared with Cr treatment alone, exogenous Se reduced root Cr content by 17%. Se supply changed the subcellular distribution of Cr in root, and the concentration of Cr was reduced in the fractions of plastids and mitochondria, while increased in soluble fraction. Besides, exogenous Se counteracted the nutrient elements (Na, Ca, Fe, Mn, Cu and Zn) loss induced by Cr. For plant with Se pretreatment, the increase rate of Cr influx was lower than that of plant without Se pretreatment, particularly in solution containing high concentration (100–400 μmol L−1) of Cr. In addition, higher Km value was observed in plant with Se pretreatment, which indicated a lower Cr affinity than that of plant without Se pretreatment. The results suggest that Se modified root morphology and regulated nutrient elements uptake by root, which might play a combined role in reducing Cr uptake by root, consequently alleviating Cr stress and maintaining plant growth.

Alpha-Granules in Resting Human Platelets Are a Spatially Clustered, Single Major Population

We interrogated in 3D-space the arrangement of alpha-granules and their proteins within 30 human platelets in order to address two central structure/function questions. First, are alpha-granules based on their size, shape and protein content a single population or not, and second, what implications could organelle frequency and organization within the resting platelet have for platelet biogenesis and membrane fusion events in activated platelets? We used serial block face scanning electron microscopy (SBF-SEM) to render in full platelet volume the ultrastructure of alpha-granules, dense granules, mitochondria, canalicular system (CS), and plasma membrane (PM) in 30 platelets, 10 each from 3 donors. Size and shape were measured for 1488 a-granules. Compositional data were assessed for multiple proteins over hundreds of granules by 3D-structured illumination microscopy (SIM) and serial section cryo-immunogold electron microscopy. Data analysis led to 3 conclusions: 1) Based on size, shape and protein composition, there was one major population of alpha-granules in resting human platelets, 2) Alpha-granules clustered tightly together while dense granules were more peripherally located and distal from one another suggesting a spatial arrangement that in the one case supports compound granule fusion and in the other case rapid fusion with the PM, and 3) Based on the weak relationship between platelet size and organelle number and volume, we inferred that platelet biogenesis is likely relatively imprecise with alpha-granule inclusion being more precisely metered than that of other organelles,. These results provide a strong, informative baseline for a-granule structural properties and suggest a spatial clustering of organelles within the resting platelet that may be functionally significant during platelet activation. DisclosuresNo relevant conflicts of interest to declare.

Morphological and anatomical changes of Phragmites australis Cav. due to the uptake and accumulation of heavy metals from polluted soils

The effect of strong chemical contamination of soils on the growth and structure of reed (Phragmites australis Cav.) roots and stems has been investigated. Soils and plants on monitoring plots in the zone of industrial sewage tanks and sludge reservoirs in the city of Kamensk-Shakhtinskii (southern Russia) were studied. Polyelement pollution of soils on the studied monitoring plots was revealed, with exceedances of Clarkes in hundreds of times for Zn and Cd, in tens of times for Pb, and in several times for Cu, Ni, Cr, and Mn. An ecological-geochemical estimation revealed an extremely hazardous level of soil contamination HMs in total. It is shown that the high level of soil contamination decelerates the ontogenetic development of plants and decreases their morphometric parameters. Electron-microscopic study of plants revealed changes in the ultrastructure of cell membranes, as well as the main cytoplasmic organelles of root and stem cells (mitochondria, plastids, etc.). It is suggested that the revealed structural changes in epidermis and mesoderm under the impact of metals hamper the radial migration of fluid in the root from the peripheral parts. These changes are one of the reasons for the decrease in the level of nutrient uptake and translocation from roots to shoots.

Quantifying spatial and temporal variations of the cell membrane ultra-structure by bimFCS.

It has been long recognized that the cell membrane is heterogeneous on scales ranging from a couple of molecules to micrometers in size and hence diffusion of receptors is length scale dependent. This heterogeneity modulates many cell-membrane-associated processes requiring transient spatiotemporal separation of components. The transient increase in local concentration of interacting signal components enables robust signaling in an otherwise thermally noisy system. Understanding how lipids and proteins self-organize and interact with the cell cortex requires quantifying the motion of the components. Multi-length scale diffusion measurements by single particle tracking, fluorescence correlation spectroscopy (FCS) or related techniques are able to identify components being transiently trapped in nanodomains, from freely moving one and from ones with reduced long-scale diffusion due to interaction with the cell cortex. One particular implementation of multi-length scale diffusion measurements is the combination of FCS with a spatially resolved detector, such as a camera and two-dimensional extended excitation profile. The main advantages of this approach are that all length scales are interrogated simultaneously, uniquely permits quantifying changes to the membrane structure caused by extrenal or internal perturbations. Here, we review how combining total internal reflection microscopy (TIRF) with FC resolves the membrane organization in living cells. We show how to implement the method, which requires only a few seconds of data acquisition to quantify membrane nanodomains, or the spacing of membrane fences caused by the actin cortex. The choice of diffusing fluorescent probe determines which membrane heterogeneity is detected. We review the instrument, sample preparation, experimental and computational requirements to perform such measurements, and discuss the potential and limitations. The discussion includes examples of spatial and temporal comparisons of the membrane structure in response to perturbations demonstrating the complex cell physiology.

A proteomic and ultrastructural characterization of Aspergillus fumigatus' conidia adaptation at different culture ages

The airborne fungus Aspergillus fumigatus is one of the most common agents of human fungal infections with a remarkable impact on public health. However, A. fumigatus conidia atmospheric resistance and longevity mechanisms are still unknown. Therefore, in this work, the processes underlying conidial adaptation were studied by a time course evaluation of the proteomics and ultrastructural changes of A. fumigatus' conidia at three time-points selected according to relevant changes previously established in conidial survival rates. The proteomics characterization revealed that conidia change from a highly active metabolic to a dormant state, culminating in cell autolysis as revealed by the increased levels of hydrolytic enzymes. Structural characterization corroborates the proteomics data, with noticeable changes observed in mitochondria, nucleus and plasma membrane ultrastructure, accompanied by the formation of autophagic vacuoles. These changes are consistent with both apoptotic and autophagic processes, and indicate that the changes in protein levels may anticipate those in cell morphology. SignificanceThe findings presented in this work not only clarify the processes underlying conidial adaptation to nutrient limiting conditions but can also be exploited for improving infection control strategies and in the development of new therapeutical drugs. Additionally, the present study was deposited in a public database and thus, it may also be a valuable dataset to be used by the scientific community as a tool to understand and identified other potential targets associated with conidia resistance.

Morphological characterisation of lettuce plasma membrane ultrastructure and vesicle formation caused by nonylphenol: A scanning electron microscopy study

Fresh produce can come into contact with nonylphenol (NP), a widely used surfactant and industrial endocrine disrupting chemical, through various routes of exposure in the agricultural environment. Nonylphenol has been linked to immunological and behavioural abnormalities as well as infertility and cancer in mammals. One of its modes of action is believed to be through damaging the plasma membrane of cells. While it has been demonstrated that NP can be phytotoxic, its effect on plant cell membrane integrity has not yet been examined. In this study, the plasma membranes of lettuce protoplasts were analysed with a high- resolution scanning electron microscope (SEM). The protoplasts were isolated from plants that had been exposed to 800, 1600, 3200, 6400 and 12,800μg/l NP, respectively, for three weeks. The plasma membrane of the protoplasts that were exposed to 6400 and 12,800μg/l NP showed vesicle-like protrusions, accompanied by flattening of the membrane in its direct vicinity. This study showed that NP caused changes in the ultrastructure of lettuce plasma membranes, thereby compromising its functionality. To the best of our knowledge, this paper describes for the first time the morphology of the plasma membrane using high-resolution SEM.

The Effect of Propofol on Plasma Membrane Ultrastructure in the Intact Cells

Despite many observed effects of anesthetic drugs, the mechanism of general anesthesia is still unknown.One well-studied drug used for human anesthesia, propofol, has been shown to interact with some ligand gated ion-channels. However, propofol also easily dissolves in the lipid bilayer and alters membrane fluidity. Which mechanism dominates in anesthesia or even how anesthesia arises are unclear. Here, we study the influence of propofol on plasma membrane (PM) ultrastructure in intact cells, which affect cell signaling. In the PM, transient submicroscopic nano-domains form by interactions between lipid-acyl-chains or lipid head groups, stabilized by cholesterol. In addition, membrane cytoskeleton may further regulate these nano-domains. These domains regulate receptor interactions and signaling.We study transient propofol affects on these domains from low to clinically relevant propofol concentrations by analyzing diffusion of GFP-tagged outer leaflet/inner leaflet membrane proteins.Using bimFCS we measure diffusion on multiple length scales simultaneously. We observe that at lower propofol concentrations (up to 2υM), the cholesterol nano-domains trap the GPI-mGFP less, which is consistent with the recent studies showing that propofoldecreases the phase transition temperature of plasma membrane derived vesicles. Interestingly, at higher concentrations of propofol (20υM to 150υM), the nanodomains trap the GPI-mGFP more strongly. This is only observed at physiological temperatures (37°C). By inhibiting myosin activity or actin filaments (de-)polymerization, we find that the activity of actin filaments further alters the behavior of cholesterol nano-domains due to propofol. We compare the effect of propofol and its analog confirming its specific effect as anesthetic drug. These results suggest that in intact cells, propofol induced cholesterol nano-domains changes are temperature dependent, regulated by cytoskeleton activities, and the effect is specific comparing to its analogs.

Effects of Propofol on Several Membrane Characteristics of Cervical Cancer Cell Lines

Background: Although significant advances have been made toward understanding the molecular mechanisms underlying the effect of propofol on tumor cell metastasis, less is known regarding how cell membrane and cytoskeletal ultrastructure are affected in this process. Here, we investigated the relationship between cell morphology and cell size, which are features mainly defined by the cytoskeleton. Methods: To confirm the effects of propofol on the migratory ability of human cervical carcinoma cells, cell migration and invasion were examined through scratch wound healing and transwell membrane assays. Furthermore, HeLa cells cultivated with different concentrations of propofol were examined by confocal microscopy and atomic force microscopy (AFM), and the mean optical density and migration ability of these cells were also assessed. In addition, cell membrane morphology was inspected using AFM. Results: The results of the wound healing and transwell membrane assays indicated that propofol decreases the migratory ability of cervical carcinoma cells compared to control cells. A comparative analysis of the test results revealed that short-term (3 h) exposure to propofol induced marked changes in cell membrane microstructure and in the cytoskeleton in a dose-dependent manner. These morphological changes in the cell membrane were accompanied by cytoskeleton (F-actin) derangement. The present findings demonstrate a close relationship between changes in cell membrane ultrastructure and cytoskeletal alterations (F-actin) in propofol-treated HeLa cells. AFM scanning analysis showed that cell membrane ultrastructure was significantly changed, including a clear reduction in membrane roughness. Conclusion: The influence of propofol on the HeLa cell cytoskeleton can be directly reflected by changes in cellular morphology, as assessed by AFM. Moreover, the use of AFM is a good method for investigating propofol-mediated changes within cytoskeletal ultrastructure.

Differential Effects of Cr(VI) on the Ultrastructure of Chloroplast and Plasma Membrane of Salvinia minima Growing in Summer and Winter. Relationships With Lipid Peroxidation, Electrolyte Leakage, Photosynthetic Pigments, and Carbohydrates

Seasonal variations of chloroplast thylakoids and plasma membrane ultrastructure and changes in some biochemical parameters (e.g., metal accumulation, photosynthetic pigments, carbohydrates, lipid peroxidation, and electrolyte leakage) were studied in fronds of Salvinia minima plants exposed to increasing concentrations of Cr(VI) in both winter and summer. Disorganization of stacked (grana) and unstacked (stroma lamellae) thylakoids was greater in winter chloroplasts than in summer chloroplasts. Plasma membrane was less affected than thylakoids. Photosynthetic pigments, lipid peroxidation, soluble sugars, and starch were affected differently in winter and summer. Our results suggest that much greater ultrastructural alterations and changes in metabolite levels occurring in winter fronds are produced by higher oxidative stress resulting from the interactive effect between low temperature, low solar irradiance, and Cr(VI) toxicity, rather than from metal accumulation per se. Seasonal differences occurring in chloroplast ultrastructure and metabolite concentrations were discussed in relation to metabolic implications. Evaluated parameters represent a relevant approach to enhance knowledge on performance and fitness of plants exposed to heavy metals under fluctuating environmental conditions. This work also indicates that selection of suitable macrophytes to remove Cr(VI) requires an additional analyzing focus on structural and metabolic interactions that occur in plants exposed to heavy metals in contrasting seasons.

Cytotoxic effects of betaxolol on healthy corneal endothelial cells both in vitro and in vivo.

To demonstrate the cytotoxic effect of betaxolol and its underlying mechanism on human corneal endothelial cells (HCE cells) in vitro and cat corneal endothelial cells (CCE cells) in vivo, providing experimental basis for safety anti-glaucoma drug usage in clinic of ophthalmology. In vivo and in vitro experiments were conducted to explore whether and how betaxolol participates in corneal endothelial cell injury. The in vitro morphology, growth status, plasma membrane permeability, DNA fragmentation, and ultrastructure of HCE cells treated with 0.021875-0.28g/L betaxolol were examined by light microscope, 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay, acridine orange (AO)/ethidium bromide (EB) double-fluorescent staining, DNA agarose gel electrophoresis, and transmission electron microscope (TEM). The in vivo density, morphology, and ultrastructure of CCE cells, corneal thickness, and eye pressure of cat eyes treated with 0.28g/L betaxolol were investigated by specular microscopy, applanation tonometer, alizarin red staining, scanning electron microscope (SEM), and TEM. Exposure to betaxolol at doses from 0.0875g/L to 2.8g/L induced morphological and ultrastructural changes of in vitro cultured HCE cells such as cytoplasmic vacuolation, cellular shrinkage, structural disorganization, chromatin condensation, and apoptotic body appearance. Simultaneously, betaxolol elevated plasma membrane permeability and induced DNA fragmentation of these cells in a dose-dependent manner in AO/EB staining. Furthermore, betaxolol at a dose of 2.8g/L also induced decrease of density of CCE cells in vivo, and non-hexagonal and shrunk apoptotic cells were also found in betaxolol-treated cat corneal endothelia. Betaxolol has significant cytotoxicity on HCE cells in vitro by inducing apoptosis of these cells, and induced apoptosis of CCE cells in vivo as well. The findings help provide new insight into the apoptosis-inducing effect of anti-glaucoma drugs in eye clinic.

Effect of tripterine on surface ultrastructure and proliferative activity of Raji cells

Objective To investigate the effect of tripterine on surface ultrastructure and proliferative activity of Burkitt lymphoma cell line Raji.Methods Raji cells were treated with different concentrations(0.5,1.0,1.5,and 2.0 μg/ml) of tripterine.Then the proliferation of Raji cells was determined by CCK8 assay,the cell membrane ultrastructure was analyzed by atomic force microscope,the apoptosis of cells was determined by Hoechst 33258 staining and flow cytometric analysis,and the cell cycle was assayed by flow cytometry.Results CCK8 assay showed that the survival rate of cells decreased from(80.67 ± 2.08) % to(38.53 ± 2.25) % 24 h after treatment with different concentrations of tripterine.The cell survival rate decreased from(74.17 ± 3.20) % to(33.22 ± 1.64) % 48 h after treatment.Tripterine significantly inhibited the proliferation of Raji cells and the inhibition was in a time-and concentration dependent manner.Atomic force microscope scan showed that the untreated Raji cells were round,with relatively smooth surface.After Raji cells were treated with 2.0 μg/ml tripterine for 24 h and 48 h,the ultrastructure of the cell membrane was collapsed,and the cell surface was rough and uneven.Hoechst 33258 staining demonstrated apoptotic cells.Apoptotic rate of the Raji cells increased from(3.50 ± 1.73) % to(38.27 ± 6.05) % 24 h after treatment with different concentrations of tripterine.Flow cytometry analysis showed that 24 h after treatment with 1.5 μg/ml tripterine,S phase Raji cells were significantly increased compared with control group(P0.05).Conclusion Our results demonstrate that tripterine can alter the cell membrane ultrastructure of Raji cells and can inhibit Raji cell proliferation through inducing cell apoptosis.

Hydroxyl radical scavenging mechanism of human erythrocytes by quercetin–germanium (IV) complex

Quercetin is a popular flavonoid in plant foods, herbs, and dietary supplement. Germanium, a kind of trace elements, can enhance the body immunity. This study investigated the hydroxyl-radical-scavenging mechanism of the quercertin–germanium (IV) (Qu–Ge) complex to human erythrocytes, especially the effects on ultrastructure and mechanical properties of cell membrane, plasma membrane potential and intracellular free Ca2+ concentration. Results showed that QuGe2, a kind of the Qu–Ge complex, could reduce the oxidative damage of erythrocytes, change the cell-surface morphology, and partly recover the disruption of plasma membrane potential and intracellular free Ca2+ level. Atomic force microscopy (AFM) was used to characterize the changes of the cell morphology, cell-membrane ultrastructure and biophysical properties at nanoscalar level. QuGe2 has triggered the antioxidative factor to inhibit cellular damage. These results can improve the understanding of hydroxyl-radical-scavenging mechanism of human erythrocytes induced by the Qu–Ge complex, which can be potentially developed as a new antioxidant for treatment of oxidative damage.

P7 peptides suppress the proliferation of K562 cells induced by basic fibroblast growth factor

Although it has been known that basic fibroblast growth factor (bFGF) is involved in tumor progression, few studies addressed the role of bFGF in hematopoietic system malignancies including chronic myeloid leukemia (CML). An elevated level of bFGF was recently found in CML patients, and bFGF was considered to play an important role in stimulating the growth of leukemia cells. Suppression of the mitogenic activity of bFGF may contribute to CML therapy. We have previously obtained a novel bFGF-binding peptide (named P7) with strong inhibitory activity against bFGF-induced cell proliferation. In this study, we investigated the effects of P7 on the proliferation of K562 cells derived from CML. The results demonstrated that P7 inhibited bFGF-stimulated proliferation, arrested the cell cycle at the G0/G1 phase, repressed the activation of MAP kinase, reversed the effects of bFGF on cell membrane ultrastructure, and caused significant changes in the expression of proteins related to proliferation. Our results suggested that the bFGF-binding peptide may have a potential antitumor effect on CML from the point of view of targeting bFGF.

Changes in non protein thiols, some antioxidant enzymes activity and ultrastructural alteration in radish plant (Raphanus sativus L.) grown under lead toxicity.

Forty days old radish plants (Raphanus sativus L.) were exposed to different regimes of lead stress as Pb(NO3)2 at the following concentrations 0, 25, 50, 100, 150, 250 and 500 ppm. The possible generation of oxidative stress, antioxidant metabolism and changes in the chloroplast and cell membrane ultrastructure were investigated. Greater loss of the photosynthetic pigments (Chl. a, Chl. b and total carotenoids) were observed especially under 500 ppm lead (Pb). The accumulation of lead in roots and leaves of plant were measured and the results showed that lead accumulation increased with increasing of the metal treatment concentration. An increasing trend was observed in levels of ascorbate and decreasing trend in glutathione. Also, the antioxidant enzymes, viz., guaiacol peroxidase (GPX) ascorbate peroxidase (APX), catalase (CAT) and glutathione S-transferase (GST) showed significant variation with the increase in lead stress compared to control (untreated) plants. The rapid inducibility of some of these enzymes is useful early and sensitive indicators of heavy metal toxicity. Native polyacrylamide gel electrophoresis revealed an increase in the isoenzymes profile of CAT in both leaves and roots. While POD isoenzymes bands prominently increased in leaves and slightly decreased in roots at the higher Pb concentration in the growth media. The ultrastructural studies at selected concentrations; 100 and 500 ppm of Pb showed distortion of the structure and cell membranes in roots. Therefore, the changes in the levels of some antioxidants may play an important role against oxidative injury.