Conjugated linoleic acids diminish glycogen synthase and glycogen synthase kinase-3 expression in muscle cells of C57BL/6J mice - in vitro and in vivo study

Conjugated linoleic acids (CLA) have been extensively advertised as dietary supplements to reduce fat and increase muscle mass. However, the role of CLA in glycogen metabolism is still largely unknown. The aim of this study was to assess the effect of CLA on glycogen synthesis in vitro (CCL 136 cell line human) and CLA in vivo (C57BL/6J mice). The materials used were the CCL 136 muscle cell line and muscles of female C57BL/6J mice (n = 52), housed at animal laboratory facility and feed with "MURIGRAN", a standard feed prepared for rodents (Agropol, Poland). Chemically pure fatty acids were added to soybean oil. CLA isomers (c9,t11 CLA, t10,c12 CLA, and as a mixture (1:1)) were administered with feed. Supplementation in mice started at week 6 of age and lasted for 4 weeks. Methods used in the study were real time- PCR - quantification of gene expression, Western blot glycogen synthase kinase-3 (GSK3α 9) and glycogen synthase (GS) protein, glycogen staining by PAS. Quantitative determination of glycogen by spectrophotometry and intracellular reactive oxygen species was measured the intracellular oxidation of dichloro-dihydro-fluorescein diacetate (DCFH-DA). In vitro data showed that GS and GSK3 expression was lower in cells cultured with different CLAs and a mixture of CLAs. GS gene expression was significantly decreased in cells cultured with c9, t11 CLA (P < 0.04) and t10, c12 CLA (P < 0.05) as well as the mixture of both isomers. The GSK3α gene expression was reduced in cells cultured with a mixture of CLA (P < 0.02), whereas phosphorylation of GSK3α increased in cells cultured with c9, t11 CLA GSK3α (P < 0.05). In vivo data showed a reduction in the glycogen concentration among mice fed a diet containing t10, c 12 CLA and a mixture of CLA isomers. We conclude that both CLA isomers can affect the synthesis of glycogen in muscle cells through the regulation of GS and GSK3α gene expression.

Pre-and postnatal exposition to fluorides induce changes in rats liver morphology by impairment of antioxidant defense mechanisms and COX induction

INTRODUCTION

Fluorides are common in the environment and are absorbed mostly in the stomach and gut, it can easily move through cell membranes and its accumulation can cause harmful effects in skeletal and soft tissues. One of the most important F- accumulation sites is the liver. The aim of this study was to determine whether F- can cause inflammation in rat liver by affecting the activity of antioxidant enzymes and changes in the synthesis of prostaglandin E2 (PGE2) and thromboxane B2 (TXB2).

MATERIALS AND METHODS

An in vivo model of prenatal and postnatal exposure to sodium fluoride (NaF) was used to carry out the experiment. Animals from control group received tap water to drink, while animals exposed to F- received drinking water containing NaF, 50 mg/L. In serum and liver we analyzed F- concentration, in liver - antioxidant enzymes activity, PGE2 and TXB2 concentration and immunolocalization of COX1 and COX2 proteins were measured.

RESULTS

We observed significant changes in F- concentration only in liver. The results of this study showed that F- affects antioxidant enzymes activity, COX2 protein expression and PGE2 synthesis in liver. Also, in some regions of the liver of rats exposed to F-, the hepatocytes were diffusely altered, with changes resembling microvesicular steatosis.

CONCLUSION

Chronic exposure to F^- during development causes an accumulation of this element in the liver and changes in antioxidant enzymes activity and cyclooxygenase expression. Long term exposure to this element is toxic to the liver and can cause disturbances in its homeostasis.

Relationship between antioxidant defense in Acanthamoeba spp. infected lungs and host immunological status

The role of oxidative stress in the pathogenicity of acanthamoebiasis is an important aspect of the intricate and complex host-parasite relationship. The aim of this experimental study was to determine oxidative stress through the assessment of lipid peroxidation product (LPO) levels and antioxidant defense mechanism in Acanthamoeba spp. lung infections in immunocompetent and immunosuppressed hosts. In Acanthamoeba spp. infected immunocompetent mice we noted a significant increase in lung lipid peroxidation products (LPO) at 8 days and 16 days post infection (dpi). There was a significant upregulation in lung LPO in immunocompetent and immunosuppressed mice infected by Acanthamoeba spp. at 16 dpi. The superoxide dismutase activity decreased significantly in lungs in immunosuppressed mice at 8 dpi. The catalase activity was significantly upregulated in lungs in immunocompetent vs. immunosuppressed group and in immunocompetent vs. control mice at 16 dpi. The glutathione reductase activity was significantly lower in immunosuppressed group vs. immunosuppressed control at 24 dpi. We found significant glutathione peroxidase downregulation in immunocompetent and immunosuppressed groups vs. controls at 8 dpi, and in immunosuppressed vs. immunosuppressed control at 16 dpi. The consequence of the inflammatory response in immunocompetent and immunosuppressed hosts in the course of experimental Acanthamoeba spp. infection was the reduction of the antioxidant capacity of the lungs resulting from changes in the activity of antioxidant enzymes. Therefore, the imbalance between oxidant and antioxidant processes may play a major role in pathology associated with Acanthamoeba pneumonia.

Beer as a Rich Source of Fluoride Delivered into the Body

Fluoride is an element which in the minimum amount is necessary for the proper construction of the teeth and bones. But on the other hand, it increases the synthesis of reactive oxygen species, inflammatory mediators, and impairs the action of enzymes. Beer is the most popular alcoholic beverage in the world. Due to its prevalence and volume of consumption, it should be considered as a potential source of F- and taken into account in designing a balanced diet. Therefore, the aim of this study was to analyze beer samples in terms of F- levels. The concentrations of fluoride were examined using ion-selective electrode Thermo Scientific Orion and statistical analysis was based on two-way ANOVA and t test. When compared to imported beers, Polish beers were characterized by the lowest mean F- concentration (0.089 ppm). The highest mean F- concentrations were recorded in beers from Thailand (0.260 ppm), Italy (0.238 ppm), Mexico (0.210 ppm), and China (0.203 ppm). Our study shows that beer is a significant source of fluoride for humans, which is mainly associated with the quality of the water used in beer production.

The Influence of Fluorine on the Disturbances of Homeostasis in the Central Nervous System

Fluorides occur naturally in the environment, the daily exposure of human organism to fluorine mainly depends on the intake of this element with drinking water and it is connected with the geographical region. In some countries, we can observe the endemic fluorosis-the damage of hard and soft tissues caused by the excessive intake of fluorine. Recent studies showed that fluorine is toxic to the central nervous system (CNS). There are several known mechanisms which lead to structural brain damage caused by the excessive intake of fluorine. This element is able to cross the blood-brain barrier, and it accumulates in neurons affecting cytological changes, cell activity and ion transport (e.g. chlorine transport). Additionally, fluorine changes the concentration of non-enzymatic advanced glycation end products (AGEs), the metabolism of neurotransmitters (influencing mainly glutamatergic neurotransmission) and the energy metabolism of neurons by the impaired glucose transporter-GLUT1. It can also change activity and lead to dysfunction of important proteins which are part of the respiratory chain. Fluorine also affects oxidative stress, glial activation and inflammation in the CNS which leads to neurodegeneration. All of those changes lead to abnormal cell differentiation and the activation of apoptosis through the changes in the expression of neural cell adhesion molecules (NCAM), glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and MAP kinases. Excessive exposure to this element can cause harmful effects such as permanent damage of all brain structures, impaired learning ability, memory dysfunction and behavioural problems. This paper provides an overview of the fluoride neurotoxicity in juveniles and adults.

The effect of low levels of lead (Pb) in the blood on levels of sphingosine-1-phosphate (S1P) and expression of S1P receptor 1 in the brain of the rat in the perinatal period

Sphingolipids are the main components of the lipid membrane. They also perform structural functions and participate in many signal transmission processes. One of the bioactive sphingolipids is sphingosine-1-phosphate (S1P), a ligand for five G protein-coupled receptors (S1PRs1-5), which can also act as an intracellular second messenger. S1P is responsible for the stimulation of progenitor cells in the brain, but it can also induce apoptosis of mature neurons. This study is aimed at assessing the effect of pre- and neonatal exposure to permissible Pb concentrations on S1P levels and S1PR1 (EDG1) expression in the prefrontal cortex, cerebellum, and hippocampus of rats. The concentrations of S1P were determined by RP-HPLC, S1PR1 expression was determined by RT PCR and Western Blot, and receptor immunolocalization was determined by immunohistochemistry method. Our results showed that even low blood Pb concentrations, i.e. within the acceptable limit of 10 μg/dL caused changes in the concentration of S1P in the cerebellum, prefrontal cortex, and hippocampus. Our data also showed a significant decrease in the level of S1PR1 in all studied part of brain, without significant changes in S1PR1 gene expression. Pre- and neonatal exposure to Pb also resulted in a decrease in the expression of S1PR1 in glial cells in all regions of the Cornu Ammonis (CA1-CA4) and Dentate Gyrus in the hippocampus, as well as in all layers of the cerebellum and prefrontal cortex, compared to the unexposed control group.

The inflammatory effect of infection with Hymenolepis diminuta via the increased expression and activity of COX-1 and COX-2 in the rat jejunum and colon

The aim of this study was to determine whether Hymenolepis diminuta may affect the expression and activity of cyclooxygenase 1 (COX-1) and cyclooxygenase 2 (COX-2), resulting in the altered levels of their main products - prostaglandins (PGE2) and thromboxane B2 (TXB2). The study used the same experimental model as in our previous studies in which we had observed changes in the transepithelial ion transport, tight junctions and in the indicators of oxidative stress, in both small and large intestines of rats infected with H. diminuta. In this paper, we investigated not only the site of immediate presence of the tapeworm (jejunum), but also a distant site (colon). Inflammation related to H. diminuta infection is associated with the increased expression and activation of cyclooxygenase (COX), enzyme responsible for the synthesis of PGE2 and TXB2, local hormones contributing to the enhanced inflammatory reaction in the jejunum and colon in the infected rats. The increased COX expression and activity is probably caused by the increased levels of free radicals and the weakening of the host's antioxidant defense induced by the presence of the parasite. Our immunohistochemical analysis showed that H. diminuta infection affected not only the intensity of the immunodetection of COX but also the enzyme protein localization within intestinal epithelial cells - from the entire cytoplasm to apical/basal regions of cells, or even to the nucleus.

Propylparaben-induced disruption of energy metabolism in human HepG2 cell line leads to increased synthesis of superoxide anions and apoptosis

The effect of propylparaben (in final concentrations 0.4 ng/ml, 2.3 ng/ml and 4.6 ng/ml) on the energy metabolism of HepG2 hepatocytes, superoxide anion synthesis, apoptosis and necrosis is described. Propylparaben can be toxic to liver cells due to the increased production of superoxide anions, which can contribute to a reduced concentration of superoxide dismutase in vivo and impairment of the body's antioxidant mechanisms. Finally, a further reduction in the mitochondrial membrane potential and uncoupling of the respiratory chain resulting in a reduction in ATP concentration as a result of mitochondrial damage may lead to cell death by apoptosis.

The Fluoride Content of Yerba Mate Depending on the Country of Origin and the Conditions of the Infusion

There are many reports of the positive effect of yerba mate on the human body. Elemental composition analysis of yerba mate revealed the presence of many microelements and macroelements, but there is no literature data referencing the content and the effect of the method of preparing the yerba mate infusion on the amount of released fluoride and thus the amount of this element supplied to the human body. Therefore, in the traditional way (cold and hot), we prepared infusions of yerba mate from different countries and determined in samples content of fluoride using potentiometric method. Hot infusions resulted in statistically significant (p = 0.03) increases in the amount of fluoride released from the dried material to the water, compared to brewing with water at room temperature. The successive refills of hot water also resulted in a release of the same amount of fluoride, although smaller than the infusion with water at room temperature (at the third refill, it was statistically significantly smaller at p = 0.003). With an increase in the number of hot water refills, the amount of fluoride released from the sample portion significantly decreased. Similar results were recorded when analyzing samples depending on the country of origin. The amount of fluoride released into the water differed statistically significantly depending on the country of origin. The most fluoride was determined in the infusions of yerba mate from Argentina and the least in infusions from Paraguay.

Fluoride as a factor initiating and potentiating inflammation in THP1 differentiated monocytes/macrophages

It is well known that exposure to fluorides lead to an increased ROS production and enhances the inflammatory reactions. Therefore we decided to examine whether cyclooxygenases (particular COX-2) activity and expression may be changed by fluoride in THP1 macrophages and in this way may change the prostanoids biosynthesis. In the present work we demonstrate that fluoride increased concentration of PGE2 and TXA2 in THP1 macrophages. Following exposure to 1-10 μM NaF, COX-2 protein and COX-2 transcript increased markedly. COX-2 protein up-regulation probably is mediated by ROS, produced during fluoride-induced inflammatory reactions. Additional fluoride activates the transcription factor, nuclear factor (NF)-kappaB, which is involved in the up-regulation of COX-2 gene expression. This study indicated that even in small concentrations fluoride changes the amounts and activity of COX-1 and COX-2 enzymes taking part in the initiating and development of inflammatory process.

The content of elements in infant formulas and drinks against mineral requirements of children

The present study aimed at analysing the content of fluorine (F), calcium (Ca), magnesium (Mg), iron (Fe) and zinc (Zn) in the drinks for children and infant formulas, a popular supplement or substitute for breast milk produced from cow milk on an industrial scale. Ca, Mg, Zn and Fe concentrations were determined using atomic absorption spectrophotometer, while F levels using a potentiometric method. F levels in the examined formula samples increased with the intended age range, until the intended age of 1 year, and then decreased. A lower content of Ca, Mg and Zn was observed in formulas intended for children <1 year of age and higher for older children. Fe content increased with the age range. A statistically significant higher content of Ca, Mg, Zn and Fe in samples intended for children with phenylketonuria in comparison to those intended for healthy children or children with food allergies was noted. The content of the analysed elements in juices and nectars showed the highest contents in products intended for infants (under 6 months of age). The lowest levels of elements tested were found in drinks for children over 6 months of age. In conclusion, the concentrations of the examined elements in infant formulas and juices for children were decidedly greater than the standards for the individual age groups. Although the absorption of these elements from artificial products is far lower than from breast milk, there is still the fear of consequences of excessive concentrations of these minerals.

The effect of reactive oxygen species on the synthesis of prostanoids from arachidonic acid

Reactive oxygen species (ROS), such as hydrogen peroxide, superoxide anion radical or hydroxyl radical, play an important role in inflammation processes as well as in transduction of signals from receptors to interleukin -1β (IL-1β), tumor necrosis factor α (TNF-α) or lipopolysaccharides (LPS). NADPH oxidase increases the ROS levels, leading to inactivation of protein phosphatase 1 (PP1), protein phosphatase 2A (PP2A) and protein tyrosine phosphatase (PTP): MAPK phosphatase 1 (MKP-1). Inactivation of phosphatases results in activation of mitogen-activated protein kinase (MAPK) cascades: c-Jun N-terminal kinase (JNK), p38 and extracellular signal-regulated kinase (Erk), which, in turn, activate cytosolic phospholipase A₂ (cPLA₂). ROS cause cytoplasmic calcium influx by activation of phospholipase C (PLC) and phosphorylation of IP₃-sensitive calcium channels. ROS activate nuclear factor κB (NF-κB) via IκB kinase (IKK) through phosphoinositide 3-kinase (PI3K), tumor suppressor phosphatase and tensin homolog (PTEN) and protein kinase B (Akt/PKB) or NF-κB-inducing kinase (NIK). IKK phosphorylates NF-κB α subunit (IκBα) at Ser³². Oxidative stress inactivates NIK and IκB kinase γ subunit/NF-κB essential modulator (IKKγ/NEMO), which might cause activation of NF-κB that is independent on IKK and inhibitor of IκBα degradation, including phosphorylation of Tyr⁴² at IκBα by c-Src and spleen tyrosine kinase (Syk), phosphorylation of the domain rich in proline, glutamic acid, serine and threonine (PEST) sequence by casein kinase II and inactivation of protein tyrosine phosphatase 1B (PTP1B). NF-κB and MAPK cascades-activated transcription factor activator protein 1 (AP-1) and CREB-binding protein (CBP/p300) lead to expression of cytosolic phospholipase A₂ (cPLA₂), cyclooxygenase-2 (COX-2) and membrane-bound prostaglandin E synthase 1 (mPGES-1), and thus to increased release of arachidonic acid and production of prostaglandins, particularly prostaglandin E₂ (PGE₂). ROS increase the activity of hematopoietic-type PGD synthase (H-PGDS), and, as a result, the production of prostaglandin D₂ (PGD₂). However, the superoxide radical reacts with nitric oxide forming peroxynitrite that inactivates prostaglandin I synthase (PGIS), suppressing the production of prostaglandin I₂ (PGI₂). ROS do not affect thromboxane synthesis in a direct manner; this is achieved by an increase in cPLA₂ activity and COX-2 expression. The aim of this review was to summarize knowledge of influence of ROS on the synthesis of prostanoids from arachidonic acid.

Perinatal exposure to lead induces morphological, ultrastructural and molecular alterations in the hippocampus

The aim of this paper is to examine if pre- and neonatal exposure to lead (Pb) may intensify or inhibit apoptosis or necroptosis in the developing rat brain. Pregnant experimental females received 0.1% lead acetate (PbAc) in drinking water from the first day of gestation until weaning of the offspring; the control group received distilled water. During the feeding of pups, mothers from the experimental group were still receiving PbAc. Pups were weaned at postnatal day 21 and the young rats of both groups then received only distilled water until postnatal day 28. This treatment protocol resulted in a concentration of Pb in rat offspring whole blood (Pb-B) below the threshold of 10 μg/dL, considered safe for humans.We studied Casp-3 activity and expression, AIF nuclear translocation, DNA fragmentation, as well as Bax, Bcl-2 mRNA and protein expression as well as BDNF concentration in selected structures of the rat brain: forebrain cortex (FC), cerebellum (C) and hippocampus (H). The microscopic examinations showed alterations in hippocampal neurons.Our data shows that pre- and neonatal exposure of rats to Pb, leading to Pb-B below 10 μg/dL, can decrease the number of hippocampus neurons, occurring concomitantly with ultrastructural alterations in this region. We observed no morphological or molecular features of severe apoptosis or necrosis (no active Casp-3 and AIF translocation to nucleus) in young brains, despite the reduced levels of BDNF. The potential protective factor against apoptosis was probably the decreased Bax/Bcl-2 ratio, which requires further investigation. Our findings contribute to further understanding of the mechanisms underlying Pb neurotoxicity and cognition impairment in a Pb-exposed developing brain.

Soy isoflavones administered pre- and postnatally may affect the ERα and ERβ expression and elements' content in bones of mature male rats

The aim of this study was to assess the influence of soy isoflavones, administered pre- and later postnatally, on the estrogen receptor α (ERα) and β (ERβ) expression in bones and to examine the mineral metabolism of the skeletal system in male rats. In bones, ERs were examined with an immunohistochemical method; in blood, estradiol with chemiluminescence immunoassay and in blood and bones, calcium and magnesium with atomic absorption spectrometry and fluorides with a potentiometric method were examined. Decreased immunoexpression of ERα and the increased intensity of immunofluorescence of ERβ in osteocytes in the femur of experimental rats were observed. In the serum of treated rats, a significantly higher concentration of estradiol and lower calcium were observed. The content of magnesium and fluoride were significantly higher in the bones of the examined animals. The data presented show that pre- and postnatal supplementation of male rats with soy isoflavones may considerably increase the concentration of estrogens in serum, with a concurrent effect on the mineral composition of bones.

Fluoride in low concentration modifies expression and activity of 15 lipoxygenase in human PBMC differentiated monocyte/macrophage

Epidemiological and experimental evidences demonstrate positive correlation between environmental and occupational fluoride exposure and risk to various cardio-respiratory disorders. That fore we decided to examine the effect of fluorides on activity and expression of 15LOX enzyme which is implicated in biosynthesis of inflammatory mediators. Expression of 15LOX-1 and -2 enzymes mRNA and protein was analyzed using RT PCT and immunoblotting methods respectively whereas HPLC method was used to measure the levels of 15 lipoxygenases end products. Additionally AA and LA concentration in cells was measured using GC method. We observed that fluoride in small concentration may significantly decrease activity of 15LOX-1 and -2 in human PBMC macrophages and then concentration of its end products: 15-HETE, 12-HETE and 9+13-HODE, what may cause development of inflammation through the cholesterol arrest into the macrophages and its differentiation to foam cell. Noted by our team overexpression of the 15LOX-1 enzyme in macrophages after addition of lowest fluoride concentrations (1 and 3 μM) may be aimed at fighting inflammation development and excessive intracellular lipid accumulation. But highest fluoride concentrations (6 and 10 μM) added to cell culture slowly declined expression of this enzyme probably because of developing inflammation. Additional 15LOX-2 expression in macrophages after fluoride addition was low in 1 and 3 μM concentrations, but increased significantly after 10 μM fluoride addition what may suggest developing acute inflammation, because 15LOX-2 is associated to increased local hypoxia. This study indicated that even in small concentrations fluorides changes the amounts and activity of 15 LOX-1 and -2 enzymes taking part in the development of inflammatory process.

Activation of phospholipase A(2) by low levels of fluoride in THP1 macrophages via altered Ca(2+) and cAMP concentration

Phospholipases (PLA's) participate in the regulation of physiological and pathological processes in the cell, including the release of pro-inflammatory mediators and stimulation of inflammatory processes. It is also well known that fluoride can increase the inflammatory reactions. Therefore we decided to examine the effect of fluorides in concentrations determined in human serum on cPLA(2) and sPLA(2) activity. The incubation of macrophages in fluoride solutions significantly increased the amount of synthesized cellular cAMP, intracellular calcium and sPLA(2) activity in a dose-dependent pattern. The cPLA(2) activity, estimated by the amount of released arachidonic acid, increased significantly when 10 μM NaF was used. The results of our study suggest that fluoride may change the activity of phospholipases in macrophage cells. Probably, increased cAMP concentration activates protein kinase C (PKC) and thus stimulates PLA(2). cAMP also regulates the passage of Ca(2+) through ion channels, which additionally influence PLA(2) throughout Ca(2+)-calmodulin dependent protein kinase.

Altered energy status of primary cerebellar granule neuronal cultures from rats exposed to lead in the pre- and neonatal period

This paper examines the effect of pre- and neonatal exposure of rats to lead (0.1% lead acetate in drinking water, resulting in rat offspring whole blood lead concentration (Pb-B) 4μg/dL) on the energy status of neuronal mitochondria by measuring changes in ATP, ADP, AMP, adenosine, TAN concentration, adenylate energy charge value (AEC) and mitochondrial membrane potential in primary cerebellar granule neurons (CGC) in dissociated cultures. Fluorescence studies were performed to imaging and evaluate mitochondria mass, mitochondrial membrane potential, intracellular and mitochondrial reactive oxygen species (ROS) production. The Na(+)/K(+) ATPase activity in intact CGC was measured spectrophotometrically. Our data shows that pre- and neonatal exposure of rats to Pb, even below the threshold of whole blood Pb value considered safe for people, affects the energy status of cultured primary cerebellar granule neurons through a decrease in ATP and TAN concentrations and AEC value, inhibition of Na(+)/K(+) ATPase, and increase in intracellular and mitochondrial ROS concentration. These observations suggest that even these low levels of Pb are likely to induce important alterations in neuronal function that could play a role in neurodegeneration.

Inhibition of erythrocyte phosphoribosyltransferases (APRT and HPRT) by Pb2+: a potential mechanism of lead toxicity

Many reports show that red blood cells of people exposed to lead have a decreased ATP concentration, decreased adenylate energy charge value and many metabolic and morphological abnormalities. Since the synthesis of nucleotides in erythrocytes occurs only through salvage pathways, we hypothesized that a decrease in nucleotide concentrations may be caused by lead-induced inhibition of erythrocyte phosphoribosyltransferases: adenine APRT (EC 2.4.2.7) and hypoxanthine-guanine HPRT (EC 2.4.2.8). These enzymes enable the reutilization of purine bases (adenine, guanine, hypoxanthine) converting them to mononucleotides (AMP, GMP, IMP), substrates for the synthesis of high-energy nucleotides. To confirm the hypothesis two experiments were performed: (i) in vitro, using a lysate of human erythrocytes incubated (5, 10, 30min) with lead ions (100microM, 10microM, 1microM, 500nM, 100nM lead acetate) and 100microM sodium acetate for the control, (ii) in vivo, using a lysate of rat erythrocytes taken from rats chronically exposed to lead (0.1% lead acetate in drinking water for 9 months, resulting in whole blood lead concentration 7microg/dL). The activities of APRT and HPRT were determined using HPLC method, which allowed concurrent determination of the activity of both enzymes in erythrocyte lysates. We have shown that, lead ions: (i) moderately inhibit both phosphoribosyltransferases in erythrocytes, this influence being detectable even at very low concentrations (ii) participate in hemolysis, the intensity of which negatively correlates with the activity of phosphoribosyltransferases. Our results indicate the necessity of further research on the role of lead-induced APRT and HPRT inhibition as one of the mechanisms of lead toxicity.

Elastin degradation within the abdominal aortic aneurysm wall--relationship between intramural pH and adjacent thrombus formation

BACKGROUND

The natural history of abdominal aortic aneurysm (AAA) is wall remodelling potentially leading to a final rupture. The pathogenesis of AAA appears to be multifactorial. The aim of this pilot prospective study was to assess the relationship between the thickness of the thrombus within the abdominal aortic aneurysm, intramural pH and local elastin degradation.

MATERIALS AND METHODS

The AAA size, intraluminal thrombus (ILT) morphology and location were evaluated in 206 consecutive patients. Thirty patients with large AAA (aortic diameter > or = 50 mm) and adjacent ILT with the thinnest part < or = 10 mm and thickest > or = 25 mm, measured in the region of the maximum diameter of AAA, were included for further study. During AAA surgery intramural pH measurements were performed and specimens taken from both thin thrombus-covered and thick thrombus-covered wall for computerized morphometric analysis.

RESULTS

Mean intramural pH value was 7.21 +/- 0.18 for the wall covered by thick ILT and 7.64 +/- 0.10 for the thin one (P < 0.001). Computerized morphometric analysis demonstrated that elastin fibres in the thin thrombus-covered wall were decreased in size (for width--P < 0.0001, for length--P < 0.13), irregularly orientated (P < 0.000001) and the amount of fibres was reduced when compared to the wall covered by thick ILT (P < 0.0004).

CONCLUSION

A strong relationship between intramural pH and elastin net destruction suggests that the local alkaline status within the thin thrombus-covered part of the aneurysm wall is contributing to the elastinolytic process.

[The impact of lead ions on metabolism of erythrocytes]

Lead contamination of the environment constitutes one of the major ecological problems. The determination of blood lead concentration is essential for evaluating lead exposure. Lead ions result in changes in the activity of numerous enzymes, disturb metabolic pathways of cells (inhibition of glycolysis), and inhibit synthesis of haem and globin. However, the activity of lead via pathological formation of free radicals is thought to be one of the most important molecular mechanisms of lead toxicity. Based on available literature, the issues concerning the effect of lead on metabolism of erythrocytes is discussed in this paper.