Cell Membrane Degradation Research Articles

Optic Nerve Regeneration After Crush Remodels the Injury Site: Molecular Insights From Imaging Mass Spectrometry.

PurposeMammalian central nervous system axons fail to regenerate after injury. Contributing factors include limited intrinsic growth capacity and an inhibitory glial environment. Inflammation-induced optic nerve regeneration (IIR) is thought to boost retinal ganglion cell (RGC) intrinsic growth capacity through progrowth gene expression, but effects on the inhibitory glial environment of the optic nerve are unexplored. To investigate progrowth molecular changes associated with reactive gliosis during IIR, we developed an imaging mass spectrometry (IMS)-based approach that identifies discriminant molecular signals in and around optic nerve crush (ONC) sites.MethodsONC was performed in rats, and IIR was established by intravitreal injection of a yeast cell wall preparation. Optic nerves were collected at various postcrush intervals, and longitudinal sections were analyzed with matrix-assisted laser desorption/ionization (MALDI) IMS and data mining. Immunohistochemistry and confocal microscopy were used to compare discriminant molecular features with cellular features of reactive gliosis.ResultsIIR increased the area of the crush site that was occupied by a dense cellular infiltrate and mass spectral features consistent with lysosome-specific lipids. IIR also increased immunohistochemical labeling for microglia and macrophages. IIR enhanced clearance of lipid sulfatide myelin-associated inhibitors of axon growth and accumulation of simple GM3 gangliosides in a spatial distribution consistent with degradation of plasma membrane from degenerated axons.ConclusionsIIR promotes a robust phagocytic response that improves clearance of myelin and axon debris. This growth-permissive molecular remodeling of the crush injury site extends our current understanding of IIR to include mechanisms extrinsic to the RGC.

Further Evidence of How Unbuffered Starvation at 4°C Influences Listeria monocytogenes EGD-e, HCC23, F2365, and Scott A

The soilborne pathogen Listeria monocytogenes frequently contaminates food products and food processing environments and is able to survive desiccation, high osmotic pressures, and starvation. However, little is known about how this pathogen survives starvation at 4°C. This study provides evidence that L. monocytogenes is able to survive total nutrient starvation for 4 weeks. L. monocytogenes strains EGD-e, Scott A, F2365, and HCC23 were starved individually in sterile water. Colony counts declined over 4 weeks, with Scott A declining the most rapidly. Transmission electron microscopy images revealed degradation of starving cell membranes and altered cytosols. Starving cells were subjected to the metabolic inhibitors fluoride, arsenite, 2,4-dinitrophenol, iodoacetate, and cyanide individually. Iodoacetate, which inhibits glyceraldehyde-3-phosphate dehydrogenase, completely reduced cultivable counts below the level of detection compared with the control starving cells; 2,4-dinitrophenol, which dissipates proton motive force, almost completely reduced cultivable counts. These results suggest that L. monocytogenes strains EGD-e, Scott A, F2365, and HCC23 are actively using part of the glycolysis pathway while starving. These results suggest that starving L. monocytogenes cells retain aspects of active metabolism.

Synergistic antifungal effects of thyme essential oil and Lactobacillus plantarum cell-free supernatant against Penicillium spp. and in situ effects

This study evaluates the synergistic antifungal effects between thyme essential oils and Lactobacillus plantarum cell-free supernatant (LCFS) against Penicillium spp. and in situ antifungal activity in rice grains. Thyme essential oil and LCFS showed remarkable antifungal activities against Penicillium spp. with the minimum inhibitory concentration (MIC) of 40 and 80 µL/mL, respectively. The analysis of fractional inhibitory concentration (FIC) index showed the antifungal synergism between thyme essential oil and LCFS against Penicillium spp. with FIC index of 0.5. This synergism also resulted in fourfold reduction in their MICs when applied in combination. The antifungal modes of action were characterized by observing the changes in cell membrane permeability and degradation of fungal cell wall. The combination of thyme essential oil and LCFS (2 × MIC of each) showed remarkable in situ antifungal effect and completely inhibit the growth of Penicillium in rice seeds. The results suggested the possible applications of the observed synergism on actual crops. Practical applications Essential oils are used as preservative in food industry and high concentration of essential oil is associated with negative organoleptic characteristics. This study presented a novel approach for synergistic antifungal effects by using the combination of thyme essential oil and Lactobacillus plantarum cell-free supernatant (LCFS) against Penicillium spp. and systematic evaluation of the antifungal effect by using fractional inhibitory concentration (FIC) index method. This approach will be a role model for future research on synergism and overcome the major drawbacks of using live bacteria and the negative effects arising from antimicrobial activities of essential oils.

Revisiting the use of sPLA2-sensitive liposomes in cancer therapy

The first developed secretory phospholipase A2 (sPLA2) sensitive liposomal cisplatin formulation (LiPlaCis®) is currently undergoing clinical evaluation. In the present study we revisit and evaluate critical preclinical parameters important for the therapeutic potential and safety of platinum drugs, here oxaliplatin (L-OHP), formulated in sPLA2 sensitive liposomes. We show the mole percentage of negatively charged phospholipid needed to obtain enzyme-sensitivity for saturated systems is ≥25% for 16-carbon chain lipid membranes, and >40% for 18-chain lipid membranes, which was surprising as 25% is used clinically in LiPlaCis®. Efficient sPLA2-dependent growth inhibition of colorectal cancer cells was demonstrated in vitro, where cell membrane degradation and cytolysis depends on the sensitivity of the formulation towards the enzyme and is governed by the amount of lysolipids generated and the presence of serum proteins. We found that serum proteins did not affect the lipase activity of the enzyme towards the membranes but instead sequester the lysolipid byproducts consequently inhibiting their detergent-like cytotoxic properties. In vivo therapeutic potential and safety of the liposomes was investigated in nude mice bearing sPLA2-deficient FaDu squamous carcinoma and sPLA2-expressing Colo205 colorectal adenocarcinoma. After intravenous injections, the tumor growth was suppressed for liposomal L-OHP relative to free drug, but only a weak response was observed for both slow- and fast-releasing sPLA2-sensitive formulations compared to non-sensitive liposomes. Also, the mice did not show longer survival. In turn, for the highly sPLA2-sensitive liposomes, multiple high doses caused petechial cutaneous hemorrhages, along with multifocal hepatonecrotic lesions, suggestive of premature activation in skin and liver irrespective of sPLA2-status of the tumor engraft. These results indicate that although liposomal carriers can improve the antitumor efficacy of platinum drugs, sPLA2-triggered release suffers from a narrow therapeutic index and has safety concerns.

In vitro cytotoxicity assessment of a West Virginia chemical spill mixture involving 4-methylcyclohexanemethanol and propylene glycol phenyl ether.

Thousands of gallons of industrial chemicals, crude 4-methylcyclohexanemethanol (MCHM) and propylene glycol phenyl ether (PPh), leaked from industrial tanks into the Elk River in Charleston, West Virginia, USA, on January 9, 2014. A considerable number of people were reported to exhibit symptoms of chemical exposure and an estimated 300,000 residents were advised not to use or drink tap water. At the time of the spill, the existing toxicological data of the chemicals were limited for a full evaluation of the health risks, resulting in concern among those in the impacted regions. In this preliminary study, we assessed cell viability and plasma membrane degradation following a 24-h exposure to varying concentrations (0-1000μM) of the two compounds, alone and in combination. Evaluation of different cell lines, HEK-293 (kidney), HepG2 (liver), H9c2 (heart), and GT1-7 (brain), provided insight regarding altered cellular responses in varying organ systems. Single exposure to MCHM or PPh did not affect cell viability, except at doses much higher than the estimated exposure levels. Certain co-exposures significantly reduced metabolic activity and increased plasma membrane degradation in GT1-7, HepG2, and H9c2 cells. These findings highlight the importance of examining co-exposures to fully understand the potential toxic effects.

Fumarase activity: an in vivo and in vitro biomarker for acute kidney injury

Renal ischemia/reperfusion injury (IRI) is a leading cause of acute kidney injury (AKI), and at present, there is a lack of reliable biomarkers that can diagnose AKI and measure early progression because the commonly used methods cannot evaluate single-kidney IRI. Hyperpolarized [1,4-13C2]fumarate conversion to [1,4-13C2]malate by fumarase has been proposed as a measure of necrosis in rat tumor models and in chemically induced AKI rats. Here we show that the degradation of cell membranes in connection with necrosis leads to elevated fumarase activity in plasma and urine and secondly that hyperpolarized [1,4-13C2]malate production 24 h after reperfusion correlates with renal necrosis in a 40-min unilateral ischemic rat model. Fumarase activity screening on bio-fluids can detect injury severity, in bilateral as well as unilateral AKI models, differentiating moderate and severe AKI as well as short- and long-term AKI. Furthermore after verification of renal injury by bio-fluid analysis the precise injury location can be monitored by in vivo measurements of the fumarase activity non-invasively by hyperpolarized [1,4-13C]fumarate MR imaging. The combined in vitro and in vivo biomarker of AKI responds to the essential requirements for a new reliable biomarker of AKI.

Current understanding of chemical degradation mechanisms of perfluorosulfonic acid membranes and their mitigation strategies: a review

This article provides a comprehensive perspective of perfluorosulfonic acid fuel cell membrane degradation phenomena, reviews and appraises the effectiveness of key concepts for the mitigation strategies and identifies future research priorities.

Mitigation of PFSA membrane chemical degradation using composite cerium oxide–PFSA nanofibres

A perfluorosulfonic acid ionomer–cerium oxide nanofibre web integrated into an asymmetric composite membrane significantly reduces fuel cell membrane degradation, especially with the modified surface placed at the anode.

A General Strategy for Decoupled Hydrogen Production from Water Splitting by Integrating Oxidative Biomass Valorization.

Conventional water electrolyzers produce H2 and O2 simultaneously, such that additional gas separation steps are needed to prevent H2/O2 mixing. The sluggish anodic O2 evolution reaction (OER) always results in low overall energy conversion efficiency and the product of OER, O2, is not of significant value. In addition, the potential formation of reactive oxygen species (ROS) may lead to degradation of cell membranes and thus premature device failure. Herein we report a general concept of integrating oxidative biomass upgrading reactions with decoupled H2 generation from water splitting. Five representative biomass substrates, ethanol, benzyl alcohol, furfural, furfuryl alcohol, and 5-hydroxymethylfurfural (HMF), were selected for oxidative upgrading catalyzed by a hierarchically porous Ni3S2/Ni foam bifunctional electrocatalyst (Ni3S2/NF). All the five organics can be oxidized to value-added liquid products at much lower overpotentials than that of OER. In particular, the electrocatalytic oxidation of HMF to the value-added 2,5-furandicarboxylic acid (FDCA) was further studied in detail. Benefiting from the more favorable thermodynamics of HMF oxidation than that of OER, the cell voltage for integrated H2 production and HMF oxidation was significantly reduced by ∼200 mV relative to pure water splitting to achieve 100 mA cm-2, while the oxidation product (FDCA) at the anode was much more valuable than O2. When utilized as electrocatalysts for both cathode and anode, Ni3S2/NF demonstrated outstanding durability and nearly unity Faradaic efficiencies for both H2 and FDCA production. Overall, such an integration of oxidative biomass valorization and HER via earth-abundant electrocatalysts not only avoids the generation of explosive H2/O2 mixture and ROS, but also yields products of high value at both electrodes with lower voltage input, maximizing the energy conversion efficiency.

A specific flagellum beating mode for inducing fusion in mammalian fertilization and kinetics of sperm internalization.

The salient phases of fertilization are gamete adhesion, membrane fusion, and internalization of the spermatozoon into the oocyte but the precise timeline and the molecular, membrane and cell mechanisms underlying these highly dynamical events are far from being established. The high motility of the spermatozoa and the unpredictable location of sperm/egg fusion dramatically hinder the use of real time imaging optical techniques that should directly provide the dynamics of cell events. Using an approach based on microfluidics technology, the sperm/egg interaction zone was imaged with the best front view, and the timeline of the fertilization events was established with an unparalleled temporal accuracy from the onset of gamete contact to full sperm DNA decondensation. It reveals that a key element of the adhesion phase to initiate fusion is the oscillatory motion of the sperm head on the oocyte plasma membrane generated by a specific flagellum-beating mode. It also shows that the incorporation of the spermatozoon head is a two steps process that includes simultaneous diving, tilt, and plasma membrane degradation of the sperm head into the oocyte and subsequent DNA decondensation.

Microstructural changes while persimmon fruits mature and ripen. Comparison between astringent and non-astringent cultivars

Persimmon cultivars are classified into two categories, those that bear astringent fruit at harvest and those that bear non-astringent fruit. Causes of natural astringency loss that fruits of non-astringent cultivars undergo on tree are yet to be clarified. A physicochemical and microstructural study of the maturity process of two astringent cultivars (‘Rojo Brillante’ and ‘Giombo’), and two non-astringent ones (‘Fuyu’ and ‘Hana Fuyu’) has been carried out. Light microscopy (LM) analysis allowed visualizing the higher soluble tannins content in astringent cultivars compared to non-astringent ones in early maturity stages as well as the natural tannin insolubilization that took place in both the astringent and non-astringent cultivars during maturation and ripening. In astringent cultivars this tannin insolubilization process was gradual and led to a progressive decline in soluble tannins. In non-astringent cultivars this insolubilization was much faster than in astringent cultivars. The present study also revealed that both colour evolution and fruit softening during maturation are characteristic for each cultivar, although in all of them a strong negative correlation was observed between these two parameters. Fruit softening was associated with a gradual parenchyma structure loss due to a cell wall and membrane degradation process. The total soluble solids content was found to be a good indicator of the sugars level in non-astringent cultivars, but should be ruled out in astringent varieties.

Synthesis and application of small cationic hexamers as potential antibiotic agents

The development of antibiotic resistance among pathogenic bacteria is caused by mutations in bacterial DNA and represents a significant challenge to modern medicine. Among the several mechanisms of antibiotic action that have been documented, including inhibition of protein synthesis, inhibition of DNA synthesis, and cell membrane degradation, the delocalization of cytochrome facilitating ATP production shows great potential as a powerful emerging method in the quest to develop new therapies to fight bacterial infection. Wenzel et al. (2014) attempted to harness this technique through the synthesis of peptides consisting of arginine and tryptophan repeats (RWRWRW‐NH2) with a terminal amine group. His group found that this peptide chain interacts with the cell wall of Gram‐positive bacteria and successfully disrupts ATP synthesis and impedes osmoregulation, ultimately leading to cell death. Our project expands on this study as well as work done by John Brandt and Christopher Ferrante, former members of our lab group. We are working to find an optimal concentration of peptide hexamers that Brandt and Ferrante previously found to be effective as potential antibiotic agents using the mechanism proposed by Wenzel et al. We are using Merrifield synthesis for synthesizing the peptides KKKWWW‐NH2 and KWKWKW‐NH2, which Brandt and Ferrante have showed to be effective as antibiotic agents against a wide range of bacterial species. These peptides are being tested for antibiotic efficacy against eight Gram positive species, including Bacillus subtilis, Staphlococcus aureus, Staphlococcus epidermidis, Streptococcus pneumonia, Lactobacillus, Streptococcus pyogenes, Bacillus cereus, and Clostridium tetani. We are also further testing the specificity of these hexamers by expanding antibiotic analysis to cover a range of Gram negative bacteria, including Escherichia coli and Psuedomonas aeruginosa. Here, we will present a thorough characterization of these hexamers as potential simple yet effective antibiotic agents against a wide array of pathogenic bacterial species.Support or Funding InformationHampden‐Sydney College Honors Council

Cerebral microdialysis

AbstractCerebral microdialysis is one of the latest neuromonitoring modalities introduced to clinical practice. It is a bedside monitor used to assess brain tissue biochemistry. The principle of this technique is closely related to brain metabolism and dialysis. Microdialysis helps monitoring different metabolites related to energy and metabolic cascades (glucose, lactate and pyruvate), amino acids (glutamate) and markers of cell membrane degradation (glycerol). Its role has been established in conditions such as traumatic brain injury, subarachnoid haemorrhage, ischaemic stroke, etc. However, it is yet to be included in routine neuromonitoring as the technique is very expensive, needs technical expertise and the measurement is not continuous with a lag period in-between two readings. Till date, it is mostly used as a research tool, even though it is a very promising technique in certain clinical conditions.

3-Bromopyruvate inhibits cell proliferation and induces apoptosis in CD133+ population in human glioma.

The study was aimed to investigate the role of 3-bromopyruvate in inhibition of CD133+ U87 human glioma cell population growth. The results demonstrated that 3-bromopyruvate inhibited the viability of both CD133+ and parental cells derived from U87 human glioma cell line. However, the 3-bromopyruvate-induced inhibition in viability was more prominent in CD133+ cells at 10μM concentration after 48h. Treatment of CD133+ cells with 3-bromopyruvate caused reduction in cell population and cell size, membrane bubbling, and degradation of cell membranes. Hoechst 33258 staining showed condensation of chromatin material and fragmentation of DNA in treated CD133+ cells after 48h. 3-Bromopyruvate inhibited the migration rate of CD133+ cells significantly compared to the parental cells. Flow cytometry revealed that exposure of CD133+ cells to 3-bromopyruvate increased the cell population in S phase from 24.5 to 37.9% with increase in time from 12 to 48h. In addition, 3-bromopyruvate significantly enhanced the expression of Bax and cleaved caspase 3 in CD133+ cells compared to the parental cells. Therefore, 3-bromopyruvate is a potent chemotherapeutic agent for the treatment of glioma by targeting stem cells selectively.

Fabrication of Ag nanoparticles modified TiO2–CNT heterostructures for enhanced visible light photocatalytic degradation of organic pollutants and bacteria

TiO2 synthesized using polymeric template consisting of polyethylene glycol and polyvinyl alcohol (Tev) and loaded with different wt% of Ag (2%, 6%) was exploited to create covalent bonds with carboxylate functionalized SWCNT/MWCNT moieties. The synthesized Ag free Tev–SWCNTs as well as Ag containing Tev–SWCNTs/MWCNTs have been characterized by UV–visible diffuse reflectance, powder XRD, HRTEM, and selected area electron diffraction (SAED), photoluminescence, Raman, FTIR and N2 sorptiometry. The materials containing Ag displayed high photocatalytic activity towards degradation of rhodamine B dye under visible irradiation (λmax>450nm). Specifically TevAg6–SWCNT has shown the best performance (0.3g/l catalyst, 20ppm RhB conc. and 80min reaction time) due to the synergistic effects derived from TiO2/Ag°/SWCNT heteroarchitectures. The antibacterial activity of synthesized photocatalysts; under visible light irradiations, towards Escherichia coli and Staphylococcus aureus was tested by performing bacterial DNA and agar well diffusion method. The results revealed that TevAg6–SWCNT was able to effectively kill both gram-positive and gram-negative bacteria. Although TevAg6–SWCNT indicated higher Eg values (1.9eV) than TevAg2–MWCNT (1.75cV) and they both exposed not only Ag° nanoparticles but also Ag2O, the former sample confirmed more lethal action against bacterial growth as well as superior photodegradation activity. This was due to delaying the recombination of electrons and holes, increasing the SBET value as well as decreasing the spherical nanoparticles of Ag° to 3nm diameter. The mechanisms of the dye degradation and destruction of bacterial cell membranes indicate the efficacy of OH and O2− as reactive radical intermediates in both processes.

The EGFR pathway regulates BCRP expression in NSCLC cells: role of erlotinib.

While multidrug resistance (MDR) in cancer is well established, little is known about the cellular pathways regulating the expression and trafficking of the MDR efflux transporter like BCRP (ABCG2). Here we evaluated the role of signalling downstream of EGFR on BCRP expression and sub-cellular localization using lung cancer cells harboring BCRP but expressing various EGFR and Ras activating mutations; A549 (K-Ras-G12S), H292 wild-type EGFR and Ras, and H1650 (EGFR-DelE747-A750). Immunocytochemistry and immunofluorescence studies demonstrated that BCRP was predominantly intracellular but its expression was found also on the plasma membrane in A549 and H1650 cells with activated Ras and EGFR. Remarkably, EGFR inhibition by erlotinib at IC₅₀ concentrations induced a differential timedependent alteration in BCRP gene and protein expression. In H1650 cells, erlotinib enhanced both the total and plasma membrane degradation of BCRP by ubiquitination within 6-24 hours, whereas BCRP expression regained the original basal levels after 48 hours. In erlotinib treated H292 cells, BCRP levels decreased at 24 hours until 72 hours, whereas in A549 cells erlotinib initially reduced BCRP expression but then induced its accumulation on the plasma membrane at 72 hours. We further found that the PI3K/Akt inhibitor LY294002 down-regulated BCRP expression, hence showing that the Akt pathway is involved in the regulation of BCRP expression but not in its localization in these lung cancer cell lines. Finally, the selective BCRP transport inhibitor Ko143 did not increase erlotinib sensitivity, but did decrease the transport activity of BCRP in A549 and H1650 cells as it induced the accumulation of its transport substrate topotecan. In conclusion, our results suggest that the EGFR and Akt pathways are involved in regulation of BCRP expression, trafficking and drug transport activity. These findings warrant future studies on the pharmacologic modulation of these pathways to enhance the efficacy of anticancer combinations of erlotinib with drugs that are BCRP transport substrates.

Forecasting cell death dose-response from early signal transduction responses in vitro.

The rapid pharmacodynamic response of cells to toxic xenobiotics is primarily coordinated by signal transduction networks, which follow a simple framework: the phosphorylation/dephosphorylation cycle mediated by kinases and phosphatases. However, the time course from initial pharmacodynamic response(s) to cell death following exposure can have a vast range. Viewing this time lag between early signaling events and the ultimate cellular response as an opportunity, we hypothesize that monitoring the phosphorylation of proteins related to cell death and survival pathways at key, early time points may be used to forecast a cell's eventual fate, provided that we can measure and accurately interpret the protein responses. In this paper, we focused on a three-phased approach to forecast cell death after exposure: (1) determine time points relevant to important signaling events (protein phosphorylation) by using estimations of adenosine triphosphate production to reflect the relationship between mitochondrial-driven energy metabolism and kinase response, (2) experimentally determine phosphorylation values for proteins related to cell death and/or survival pathways at these significant time points, and (3) use cluster analysis to predict the dose-response relationship between cellular exposure to a xenobiotic and plasma membrane degradation at 24 h post-exposure. To test this approach, we exposed HepG2 cells to two disparate treatments: a GSK-3β inhibitor and a MEK inhibitor. After using our three-phased approach, we were able to accurately forecast the 24 h HepG2 plasma membrane degradation dose-response from protein phosphorylation values as early as 20 min post-MEK inhibitor exposure and 40 min post-GSK-3β exposure.

Polymer antimicrobial coatings with embedded fine Cu and Cu salt particles

Many diseases spread due to the bacterial infections, which cause significant economic and personal losses. Contact with infected surfaces is likely to catch infections. Hence, antimicrobial surfaces play an important role in public sectors that can prevent the spreading of disease and infection. Coatings on contact surfaces have been used to provide antimicrobial function. Copper (Cu), as one of the commonly used metals, has long been known to possess germ-killing properties. However, metallic Cu or Cu coatings have not been widely used for the purposes of antimicrobial due to the heavy weight, relatively high cost, limited corrosion resistance and low compatibility of the metal with substrates of non-metallic materials. We have recently developed a polymer-based coating system containing mixtures of fine particles of Cu and Cu salt, which provides excellent antimicrobial properties. The results indicate that the coating with embedded fine Cu salt showed higher antimicrobial property than the coating with only Cu due to the release of more Cu ions. The elimination of 10(6) bacteria by contacting the polymer-Cu coatings needs 8 h, while contacting with the polymer-CuCl2 coatings took only 20 min to kill the same amount of bacteria. We have also used transmission electron microscopy and synchrotron infrared microscopy technique to study the degradation of bacterial cell membrane to understand the mechanism of the antimicrobial function of Cu coating.

Does thermodynamic stability of peritoneal collagen change during laparoscopic cholecystectomies? A differential scanning calorimetry (DSC) study

BackgroundCarbon dioxide pneumoperitoneum used during laparoscopic surgeries alters the integrity of the peritoneum and results in denudation of the basal lamina that might cause altered immune response, inhibited fibrinolysis, hypoxia, and acidosis. The changes in the structure of pneumoperitoneum were described as bulging of mesothelial cells, irregular cell junction’s cell membrane degradation, and mesodermal edema. As denaturation of peritoneal proteins reflects overall condition of its structure and interactions with the surrounding molecules, the physical status of collagen was assessed on the basis of parameters of thermal denaturation measured by DSC method.MethodsTwenty-four female patients operated on due to cholelithiasis were enrolled in this study. Laparoscopic cholecystectomy was performed using standard four-trocar technique, and standard values of insufflated carbon dioxide pneumoperitoneum were used. After trocar placement, the first collection of peritoneal sample (sample A) was performed. The second peritoneal sample (sample B) was collected after the removal of gall bladder. Differential scanning calorimetry (Q200 calorimeter, TA Instruments) was performed on samples defrosted at room temperature.ResultsIn all samples of peritoneum, a nonreversible endothermal process recognized as denaturation was observed. Sample B obtained at the end of surgery did not differ from sample A obtained at the beginning in terms of all parameters under study. Temperature of denaturation in A and B was correlated only marginally, but enthalpy and specific heat were significantly correlated. The analysis of data from DSC measurements did not reveal differences in physical stability of collagen in peritoneal samples obtained at the beginning and at the end of surgery. Significant negative correlations between duration of CO2 pneumoperitoneum and enthalpy of denaturation in sample B were found.ConclusionsDifferences in enthalpy of denaturation may reflect a quantitative relation between amount of native collagen molecules in the sample and other, non-collagenous components or impaired collagen.

In vivo31P-MR spectroscopy in normal pregnancy, early and late preeclampsia: A study of placental metabolism

IntroductionPreeclampsia affects about 3% of pregnancies and the placenta is believed to play a major role in its pathophysiology. Lately, the role of the placenta has been hypothesised to be more pronounced in preeclampsia of early (<34 weeks) rather than late (≥34 weeks) onset. 31P Magnetic Resonance Spectroscopy (MRS) enables non-invasive, in vivo studies of placental metabolism. Our aim was to study placental energy and membrane metabolism in women with normal pregnancies and those with early and late onset preeclampsia. MethodsThe study population included fourteen women with preeclampsia (five with early onset and nine with late onset preeclampsia) and sixteen women with normal pregnancy (seven with early and nine with late pregnancy). All women underwent a 31P-MRS examination of the placenta. ResultsThe phosphodiester (PDE) spectral intensity fraction of the total 31P signal and the phosphodiester/phosphomonoester (PDE/PME) spectral intensity ratio was higher in early onset preeclampsia than in early normal pregnancy (p = 0.03 and p = 0.02). In normal pregnancy the PDE spectral intensity fraction and the PDE/PME spectral intensity ratio increased with increasing gestational age (p = 0.006 and p = 0.001). DiscussionSince PDE and PME are related to cell membrane degradation and formation, respectively, our findings indicate increased cell degradation and maybe also decreased cell proliferation in early onset preeclampsia compared to early normal pregnancy, and with increasing gestational age in normal pregnancy. ConclusionsOur findings could be explained by increased apoptosis due to ischaemia in early onset preeclampsia and also increased apoptosis with increasing gestational age in normal pregnancy.