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Biomedical subjects

S Pollet

Publications and source records attributed to S Pollet.

At least 19 recordsLinked to original sources
PubMed2005

Influence of subcutaneous injection of essential fatty acids on the stress-induced modifications of rat platelet aggregation and membrane lipid composition.

Membrane lipids play an important role in the function of blood platelets but the mechanisms by which the lipid composition of the platelet membrane is adjusted remain unclear. It has been shown that stress and poly-unsaturated fatty acids modified the lipid composition of blood plasma and platelet lipids, but very little is known about the effect of stress and fatty acids on membrane platelet lipid composition. The purpose of the present investigation was to study the influence of the essential fatty acids: linoleic, linolenic and arachidonic acids on the composition of the platelet membrane lipids of rats assigned to heat and restraint stress. It was shown that injections of polyunsaturated fatty acids decrease or suppress the stress-induced increase in platelet aggregation, suppress the stress-induced modification of the composition of the platelet membrane lipids and modify the fatty acid composition of the platelet membrane phospholipids.

Animals↗
PubMed2004

Administration of Zn-Co-Mn basic salt to chickens with ascaridiosis. II. Sex ratio and microelement levels in Ascaridia galli and in treated and untreated chickens.

Hisex chickens were infected with 1,450 embryonated Ascaridia galli eggs and treated with a new synthesized basic mixed salt (Zn(x)Co(y)Mn(1-x-y)) x (OH)6SO4 x 2H2O). The worm burden was determined and sex ratios for A. galli of M:F = 1.4 and M:F = 2 in untreated and treated chickens, respectively, were found. A decrease in the mean establishment rate of A. galli in treated chickens was observed. The levels of zinc, cobalt and manganese were determined in liver and muscle of the host and in male and female A. galli. The survival of the chickens and gain in body weight were improved, and the restoration of microelement content was observed by treatment with the salt. A positive effect of the basic Zn-Co-Mn salt was also observed in the nematode microelement levels. Significant differences were found between the levels of zinc, cobalt and manganese in male and female A. galli.

Animals↗
PubMed2002

[The Rel/NF-kappa-B transcription factors: complex role in cell regulation].

The transcription factor NF-kappa B has attracted widespread attention among researchers. NF-kappa B displays some original characteristics including rapid regulation, the wide range of genes that it controls and its probable involvement in several diseases. In resting cells, NF-kappa B is kept in an inactive form in the cytoplasm where it is bound to a member of the I kappa B family of inhibitory proteins. NF-kappa B can be activated by exposure of cells to physiological as well as non physiological stimuli. Upon cell activation, the inhibitors are modified through site specific phosphorylations which target them for subsequent ubiquitination and proteolytic degradation by the proteasome. Removal of the inhibitor unmasks the nuclear localization signals on subunits of NF-kappa B. Free NF-kappa B moves to the nucleus where it binds to target DNA elements and activate transcription of genes encoding proteins involved in immune responses, inflammation or cell proliferation. NF-kappa B could be considered as a co-ordinating element in the body's responses to situations of stress, infection or inflammation. A tight regulation of NF-kappa B seems to be crucial since a dysfunction could promote pathogenic processes including AIDS (acquired immunodeficiency syndrome), rheumatoid arthritis and cancer. Additionally, it will be important to understand the exact roles for NF-kappa B in regulating apoptosis. NF-kappa B is now regarded as a good therapeutic target and the development of specific inhibitors should lead in the next future to novel therapeutics.

Active Transport, Cell Nucleus↗
PubMed2002

Insight into some of the signaling pathways triggered by a lipid immunomodulator.

The use of non specific immunomodulatory agents takes an important place in the aspecific host response to invading microorganisms. In this context, antimicrobial properties of royal jelly have been ascribed to organic acids (mainly 10 hydroxy-2-decenoic acid or 10-HDA) and proteins. We synthesized a derivative of 10-HDA, the 1-(2-methoxyethoxymethyl)2,3-(10-hydroxy2-decenoyl)(E) glycerol referred as diHDA-glycerol which was previously found to protect mice against virulent Salmonella typhimurium challenge through more adequate immune regulations. This study was conducted to further investigate some of the signaling pathways followed by diHDA-glycerol in cell transduction. Members of NF-kappaB transcription factors are key regulators of many cytokines acting on immunity and they control genes involved in responses to numerous signals such as bacterial products. Therefore, we investigated some parameters acting on NF-kappaB translocation in U937 cells after diHDA-glycerol treatment. Due to the chemical structure of the molecule we also investigated the sphingomyelinase pathway. Our results showed that diHDA-glycerol induced a rapid NF-kappaB translocation as a consequence of IkappaB-alpha proteolysis. An intracellular production of reactive oxygen species (ROS) may also account for NF-kappaB activation, without de novo protein synthesis. DiHDA-glycerol induced a strong activation of neutral sphingomyelinase, suggesting an important role of sphingolipids in the regulatory responses induced by diHDA-glycerol.

Adjuvants, Immunologic↗
PubMed2000

Effect of a synthetic lipid immunomodulator on the regulation of the transcription factor NF-kappaB.

Macrophage activation plays a central role in host defense against a variety of pathogens via inducible messengers. The transcription factor NF-kappaB controls the synthesis of cytokines involved in immune responses. In quiescent cells, NF-kappaB is located in the cytosol bound to an inhibitor IkappaB. Upon appropriate signal, NF-KB translocates to the nucleus and binds to DNA. The present study investigated the involvement of an immunomodulator, (diHDA-glycerol) on the NF-kappaB/IkappaB complex. Results were compared to those obtained with lipopolysaccharide (LPS) as a major virulence factor in bacterial sepsis. Data showed that exposure of J774.1 cells either to LPS or diHDA-glycerol substantially increased with time the nuclear levels of NF-kappaB complexes. Antibodies to various NF-kappaB proteins supershifted p50, p65 and to a lesser extent c-rel. Western blot analyses showed a rapid cytosolic IkappaB-alpha turn over following LPS exposure in contrast to diHDA-glycerol treatment. Further experiments investigated the involvement of protein kinase C (PKC) by using two inhibitors, staurosporine and H7. Pretreatment of J774.1 with either inhibitor prior to diHDA-glycerol or LPS exposure decreased NF-kappaB activation. Our results indicate that diHDA-glycerol was acting on NF-kappaB through IkappaB regulative mechanisms differing from those used by LPS. DiHDA-glycerol is likely acting on many other transcription factors targeting distinct genes implied in up regulation of the immune system.

Adjuvants, Immunologic↗
PubMed1999

Changes in myosin heavy chain profile of mature regenerated muscle with endurance training in rat.

The objective of the present study was to examine the response of fast-twitch muscle to endurance training long after the muscle had regenerated from toxin injury. Seventeen male Wistar rats were randomly assigned to a sedentary (S, n = 10) or a trained group (T, n = 7). Endurance training by treadmill running (5 days week(-1), 30 m min(-1), 7% grade, 2 h day(-1) for 5 weeks) was initiated 5 weeks after myofibre degeneration was induced in the right extensor digitorum longus muscle (EDL) by two injections of 0.2 mL of the unfractionated venom from Naja nigricollis snake. Gel electrophoresis analyses showed that training alone resulted in a 140% increase in type IIX myosin heavy chain (MHC) (P < 0.01) and a slight decrease in type IIB MHC (-14% P < 0.05). Regeneration alone induced an increase in both type IIA and IIX MHC expression (103%, P < 0.05, and 131%, P < 0.01, respectively), and a concomitant decrease in the percentage of type IIB MHC (P < 0.05). The shift from type IIB toward type IIA MHC composition observed in regenerated muscles of T rats resulted not only from an additive, but from a cumulative effect of training and regeneration. Immunohistochemical analysis of MHC content in individual fibres showed similar changes. These data suggest that the impact of endurance training on fast-type MHCs was more marked in mature regenerated muscles than in regenerating ones, and provide evidence of the heightened plasticity of fully regenerated muscles to repeated exercise.

Animals↗
PubMed1997

Zinc and DNA fragmentation in keratinocyte apoptosis: its inhibitory effect in UVB irradiated cells.

Zinc has been shown to have antioxidant properties and to exhibit inhibitory effects on apoptosis. In this work we investigated the effect of zinc on DNA integrity and on apoptosis of HaCaT keratinocytes. Cells were submitted to zinc deprivation by a diffusible zinc chelator, (N,N,N',N'-tetrakis (2-pyridylmethyl)ethylenediamine) (TPEN) or supplied with zinc chloride and submitted to UVB radiation. After cell exposure to TPEN for 2 h, strand breaks significantly impaired DNA resistance to alkaline denaturation. DNA strand breaks induced by a 6 h TPEN application were significantly prevented if zinc chloride was supplied together with the chelator. TPEN also generated, after 4-6 h of application, cytoplasmic histone-associated DNA fragments (mononucleosomes and oligonucleosomes), features of cell death by apoptosis. Moreover, UVB irradiation led to early DNA strand breaks and to an increase in cytoplasmic nucleosomes which was maximum 10 h after irradiation. These effects were prevented by the supply of zinc chloride (0.1 mM) in the culture medium. These results suggest that zinc ions interfere with the apoptosis process at an early stage, by decreasing DNA damage able to trigger apoptosis.

Apoptosis↗
PubMed1989

Mesangial glomerulopathy and IgM rheumatoid factor in rheumatoid arthritis.

Hematuria and proteinuria in rheumatoid arthritis (RA) are commonly associated with drug therapy but occur independently of drugs, amyloid or urologic disorders. The latter occurrences suggest a primary renal lesion associated with RA. Review of reported renal biopsies identifies mesangial glomerulopathy as a common finding in RA patients without associated drug therapy and that it is frequently associated with hematuria in nonrheumatoid patients. Moreover, immunoglobulins have been shown to concentrate in the mesangium in experimental animals, suggesting that a functional response by the kidney mesangium to remove IgM rheumatoid factor (RF)-IgG complexes could lead to this mesangial lesion. We describe 3 patients with RA who had a mesangiopathy characterized by increased quantities of mesangial matrix and deposition of IgM without other lesions. Together, these observations suggest that: (1) mesangial glomerulopathy is common in RA; (2) removal of circulating RF-IgG complexes is a function of the mesangium and might produce this renal lesion; (3) mesangial glomerulopathy may be responsible for much of the hematuria observed in RA patients and, in many cases, may not be drug related and thus may not require discontinuing beneficial therapy.

Adult↗
PubMed1989

[Lithium found in the total brain and brain lipids after intracranial injection of lithium in mice. Relation to the observed behavior disorders].

Behavioural disturbances after lithium injection only appear in mice with concentrations above 8 microequivalents per brain. Below this value, no fixation of lithium occurs in the brain. At higher concentrations, the amount of lithium found in the brain and associated with brain lipids increases gradually to reach a plateau. Moreover, although lithium increases the extraction of proteolipids, it does not seem to have an affinity for these compounds.

Animals↗
PubMed1985

Aspirin dosing using 15 grain enteric coated tablets.

A high unit dose (15 grain/975 mg) enteric coated aspirin preparation was studied in normal individuals and patients with arthritis to determine how readily well tolerated, therapeutic (150-300 micrograms/ml) salicylate (SA) levels could be achieved using a twice daily dosing regimen. Of 36 participants enrolled, 33 (92%) achieved this goal (mean SA = 224 micrograms/ml), while in the remaining 3 an initially toxic level fell below the therapeutic range after reducing the dose by one tablet/day. Although the relationship between dose (mg/kg) and steady state SA levels was roughly linear (r = 0.74), in some subjects there was a striking incremental change in the SA level when the dose was adjusted. Over 90% of subjects taking a starting dose between 45-60 mg/kg/day achieved a therapeutic level. Thus, antiinflammatory therapy using 15 grain/975 mg enteric coated aspirin given twice daily appears to be feasible.

Adult↗
PubMed1981

Lipid analysis in nerve biopsy specimens of hypertrophic neuropathy.

We performed a lipid analysis on nerve biopsy specimens in two cases of degenerative hypertrophic neuropathy. Quantitative analysis of the major lipid classes, ie, cholesterol, cerebrosides, sulfatides, ethanolamine phospholipids, phosphatidyl-choline, phosphatidyl-serine, phosphatidyl-inositol, sphingomyelin, and gangliosides, were performed. The two cases exhibited extreme decreases in levels of lipids that could be related to the very low myelin content of these nerves. Cholesterol and phospholipid levels were especially reduced. Cerebrosides and sulfatides were not modified in the same proportion, as could have been predicted from the degree of demyelination. This relative glycolipid increase could be due to the very high Schwann cell proliferation.

Adolescent↗
PubMed1979

Analysis of the major lipid classes in human peripheral nerve biopsies. Age group differences and abnormalities of ganglioside level in perhexiline maleate therapy.

We report here the results of a simple and reproducible technique which can be used in semi-routine analysis of peripheral nerve biopsy specimens, so as to have a quantitative analysis of the major lipid classes, i.e. cholesterol, cerebrosides, ethanolamine phospholipids, phosphatidyl-choline, phosphatidyl-serine + phosphatidylinositol, sphingomyelin and gangliosides. Glycolipid hexoses, cholesterol and total phospholipids have been compared in different age groups. Although all lipid classes increased from the younger to the older age group, the molar ratio of cholesterol to phospholipid differed less than the glycolipid to phospholipid ratio. Both increased significantly, even between age group 10--16 and older patients (36, 54, 61, 68, 72 and 73 years old). Although individual variations in lipid content are noteworthy, it must be emphasized that evolution with age of the lipid composition must be taken into account. Furthermore, this study confirms and extends earlier findings of increased ganglioside levels in some cases of peripheral neuropathies observed during perhexiline maleate therapy where characteristic lipid-like polymorphous inclusions have been demonstrated.

Adolescent↗
PubMed1979

Bismuth intoxication: bismuth level in pig brain lipids and in subcellular fractions.

Experimental intoxications of pigs were performed. It seems to be confirmed that bismuth crosses the blood-brain barrier. An organic derivative, trivinyl-bismuth, is more active than the inorganic salt of bismuth. In the brain, bismuth is preferentially found in synaptosomes. Bismuth is found in brain lipids of control pigs at very low levels. In intoxicated pigs, the level of bismuth is increased mainly in cerebellum and then in thalamus. Bismuth is partly associated to lipids. There is not a correlation between the level of bismuth in blood and in brain lipids. However, in the trivinyl intoxicated pig, a high level of blood bismuth is concomittant to a high level of brain lipid bismuth. The high content of this metal in cerebellum lipid extract may be of functional significance.

Animals↗
PubMed1978

[Diffuse polymorphous inclusions in a patient treated with perhexiline maleate (author's transl)].

Case report of polyneuritis and liver dysfunction induced by perhexiline maleate in a 64 years old male patient. The ultrastructural study of nerve, liver, muscle and skin biopsies shows polymorphous, membrane bound, often multilamellar, lysosome-like inclusions, the content of which is probably complex lipids. The histochemical study of liver reveals a lipid storage, consisting mainly of triglycerides and of smaller amount of phospholipids and free fatty acids, the pattern of which is abnormal. The biochemical study of nerve tissue shows a decrease of phospholipids levels and some qualitative disturbances in gangliosides. These changes, some of which are similar to those reported in amphiphilic drug intoxications, are prevalent in high lipid metabolism cells such as hepatic and Schwann cells.

Biopsy↗
PubMed1978

[Neurological disorders and perhexiline maleate therapy. Clinical study of 10 cases. Neuropathological, pharmacocinetic and biochemical studies (author's transl)].

Ten new cases of perhexiline induced peripheral neuropathies are reported. The authors emphasize the possible association of other neurological disorders: cerebellar symptoms in one case, complex tremor in two other cases, marked decrease of photomotor reflexes in one case and disgeusia in another one. The pharmacocinetic study of 4 cases revealed the presence of a low metabolism of the drug in one of them. Polymorphous inclusions have been seen in Schwann cell and endothelial cell cytoplasm in the three patients with electron microscopic study of the nerves. The pathological study of one case showed the demyelination of spinal cord posterior columns. In another case, who died from hepatic coma, the biochemical study of cerebral lipids revealed the low values of cerebrosides and sulfatides in cerebellum and cerebral white matter.

Cerebellar Diseases↗