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Biomedical subjects

P Preziosi

Publications and source records attributed to P Preziosi.

At least 55 records · Page 3Linked to original sources
PubMed2000

Relationship between vitamin D status and skin phototype in general adult population.

A link between bone mineral density and skin color has been reported recently, and pigmentation has been shown to affect cutaneous vitamin D production. In the present study, we investigated the relationship between phototype, global self-assessed sun exposure, geographical location and vitamin D serum levels in 1191 French adults. When the factors were analyzed separately, individuals with lower phototypes as well as those with lower sun exposure showed significantly lower levels of vitamin D than those with darker phototypes or those with higher sun exposure. However, when factors were analyzed as a whole, the vitamin D status was no longer linked with the phototype, but with sun exposure and geographical location. Since phototypes and global self-assessments of sun exposure were positively linked, our data suggest that lower vitamin D levels in fair-skinned individuals are due to their sun exposure behavior.

Adult↗
PubMed2000

[Vitamin D concentrations in blood and skin phototype in a general adult population in France].

INTRODUCTION: A link between bone mineral density and skin color has been reported recently, and pigmentation has been shown to affect cutaneous vitamin D production. In the present study, we investigated the relationship between phototype, global self assessed sun exposure, geographical location and vitamin D serum levels in 1191 French adults. METHODS: Three multiple linear regression analyses were performed. The two first analyses to test separately the effect of phototype, and the effect of sun exposure on the vitamin D levels. Then, a third model was constructed, using both factors and geographical location. RESULTS: When the factors were analyzed separately, individuals with lower phototype showed significantly lower levels of vitamin D than those with darker phototype, as well as, individuals with lower sun exposure showed significantly lower levels of vitamin D than those with higher sun exposure. However in the global model, which takes into account phototype and sun exposure simultaneously together with the region of residence, the vitamin D status was no longer linked with the phototype, but with sun exposure and geographical location. CONCLUSION: Since phototype and global self-assessment of sun exposure were positively linked, our data suggest that lower vitamin D levels in fair-skinned individuals are due to their sun exposure behavior.

Adult↗
PubMed2000

Signaling pathways involved in lipopolysaccharide stimulation of prostaglandin production by rat hypothalamic astroglial cells.

The aim of this study was to investigate the mechanisms through which bacterial lipopolysaccharide (LPS) stimulates prostaglandin (PG) production in rat hypothalamic astroglial cells in vitro. The latter were treated with LPS alone or LPS plus antagonists of the interleukin-1 (IL-1) and nitric oxide (NO) pathways, and the subsequent changes in cyclooxygenase (COX) activity were monitored by measuring a COX end-product, prostaglandin E2 (PGE2), released into the incubation medium. LPS produced a concentration-dependent increase in PGE2 release from astroglia after 24 h incubation; experiments with selective antagonists showed that the increase in PGE2 release induced by LPS may be, at least in part, mediated by IL-1 and NO.

Animals↗
PubMed1999

Depolarization and a NO-donor stimulate interleukin-1beta release from the rat hypothalamus via a mechanism involving caspase 1.

Previous in vitro studies showed that rat hypothalamic explants release interleukin-1beta (IL-1beta); such release is significantly increased by several stimuli including 56 mM KCl and NO-donors in 20-min experiments. Here we tested the hypothesis that the above stimuli act via a mechanism involving cleavage of the IL-1beta precursor by interleukin-1beta converting enzyme (ICE, also referred to as caspase-1). A cell-permeable form of the caspase-1 inhibitor I and two different stimuli, 56 mM KCl and sodium nitroprusside (SNP), were used. The inhibitor was able to counteract the increase in IL-1beta release induced by both K+ and SNP, while having no effect on basal release.

Animals↗
PubMed1999

Inhibition of heme oxygenase in the central nervous system potentiates endotoxin-induced vasopressin release in the rat.

Previous in vitro studies have shown that increases in endogenous carbon monoxide (CO) generation via activation of the enzyme heme oxygenase (HO) within the rat hypothalamus are associated with the reduced release of the neuropeptides, vasopressin (AVP) and oxytocin, while evidence concerning corticotrophin-releasing hormone (CRH) is controversial. The present study investigated whether there is also a functional relationship between the HO-CO pathway and AVP and corticosterone (Cort) in vivo. Male Wistar rats were challenged with bacterial lipopolysaccharide (LPS) at doses producing significant activation of the hypothalamo-pituitary-adrenal (HPA) axis. LPS was given alone or after pretreatment with the HO inhibitor Sn-protoporphyrin-9 (SnPP9). The latter was injected either intraperitoneally (i.p.) or by intracerebroventricular (i.c.v.) route. SnPP9 given i.p. failed to modify either basal or LPS-stimulated levels of AVP and Cort. On the contrary, i.c.v. SnPP9 strongly potentiated LPS-induced AVP release and significantly enhanced basal serum Cort levels, although it failed to potentiate stimulation by LPS. The LPS + i.c.v. SnPP9 also significantly reduced the hypothalamic stores of AVP compared to controls, correlating with increased circulating levels of AVP. Taken collectively, these data are in concordance with previous in vitro observations showing that the HO-CO pathway acts centrally to attenuate endotoxin-stimulated AVP release, while having less effects on the pituitary-adrenal axis.

Animals↗
PubMed1999

Bacterial lipopolysaccharide increases prostaglandin production by rat astrocytes via inducible cyclo-oxygenase: evidence for the involvement of nuclear factor kappaB.

This study was set to investigate the mechanisms through which bacterial lipopolysaccharide (LPS) stimulates prostaglandin (PG) production in rat astrocytes. Primary cultures of rat hypothalamic astrocytes were established. Cells were treated with LPS alone or LPS plus antagonists of various pathways, and the subsequent changes in cyclo-oxygenase (COX) activity were monitored by measuring a COX end product, PGE2, released into the incubation medium. It was found that (i) LPS produced a concentration-dependent increase in PGE2 release from astrocytes. The potency of LPS was significantly increased by the addition of serum into the incubation medium; (ii) after 24 h of incubation, inducible COX (COX-2) accounts for most of the LPS-stimulated PG production, as the latter was markedly reduced by dexamethasone and the specific COX-2 inhibitor NS 398; and (iii) nuclear factor kappaB appears to play a role in the activation of COX-2 induced by LPS, since certain inhibitors of this transcription factor were able to antagonize, at least in part, the effects of LPS on PGE2 release.

Animals↗
PubMed1999

Systemic administration of cocaine, given alone or in combination with sensory stimuli, differentially affects L-arginine-nitric oxide metabolism in discrete regions of the brain of rat.

The effect of cocaine on brain regional metabolism of L-arginine to nitric oxide (NO) has been studied in rat by measuring the level of citrulline, the co-product of NO synthesis, using a HPLC based methodology. A single i.p. administration of 1 mg/kg cocaine, and a daily treatment for up to 5 consecutive days, failed to affect significantly citrulline content in the striatum, hippocampus and cortex. By contrast, in these regions of the brain a single or 5-day repeated higher dose of cocaine (10 mg/kg, i.p.) caused a significant increase in the co-product of NO synthesis and this has been abolished in a stereoselective fashion by L-NAME (10 mg/kg i.p. given 30 min before). Under cocaine high dose treatment, 1 h acoustic stimulation, which per se resulted ineffective, enhanced stimulant-induced increases in citrulline content seen in the striatum and abolished the increase of this amino acid observed in the hippocampus and cortex both after single or 5-day repeated injection of cocaine. In conclusion, these data demonstrate that cocaine stimulates the conversion of L-arginine to NO in the brain of rat and this is affected by concomitant exposure to acoustic stimulation.

Acoustic Stimulation↗
PubMed1999

Impact of trace elements and vitamin supplementation on immunity and infections in institutionalized elderly patients: a randomized controlled trial. MIN. VIT. AOX. geriatric network.

BACKGROUND: Antioxidant supplementation is thought to improve immunity and thereby reduce infectious morbidity. However, few large trials in elderly people have been conducted that include end points for clinical variables. OBJECTIVE: To determine the effects of long-term daily supplementation with trace elements (zinc sulfate and selenium sulfide) or vitamins (beta carotene, ascorbic acid, and vitamin E) on immunity and the incidence of infections in institutionalized elderly people. METHODS: This randomized, double-blind, placebo-controlled intervention study included 725 institutionalized elderly patients (>65 years) from 25 geriatric centers in France. Patients received an oral daily supplement of nutritional doses of trace elements (zinc and selenium sulfide) or vitamins (beta carotene, ascorbic acid, and vitamin E) or a placebo within a 2 x 2 factorial design for 2 years. MAIN OUTCOME MEASURES: Delayed-type hypersensitivity skin response, humoral response to influenza vaccine, and infectious morbidity and mortality. RESULTS: Correction of specific nutrient deficiencies was observed after 6 months of supplementation and was maintained for the first year, during which there was no effect of any treatment on delayed-type hypersensitivity skin response. Antibody titers after influenza vaccine were higher in groups that received trace elements alone or associated with vitamins, whereas the vitamin group had significantly lower antibody titers (P<.05). The number of patients without respiratory tract infections during the study was higher in groups that received trace elements (P = .06). Supplementation with neither trace elements nor vitamins significantly reduced the incidence of urogenital infections. Survival analysis for the 2 years did not show any differences between the 4 groups. CONCLUSIONS: Low-dose supplementation of zinc and selenium provides significant improvement in elderly patients by increasing the humoral response after vaccination and could have considerable public health importance by reducing morbidity from respiratory tract infections.

Aged↗
PubMed1999

Anaphylaxis increases 8-iso-prostaglandin F2alpha release from guinea-pig lung in vitro.

8-Iso-prostaglandin F2alpha, release from isolated and perfused guinea-pig lung was measured by radioimmunoassay. 8-Iso-prostaglandin F2alpha release was detectable under basal conditions and increased 10-fold during antigen-induced bronchoconstriction, concomitant with the increase of thromboxane B2 and prostaglandin E2. The anti-8-iso-prostaglandin F2alpha serum used in the radioimmunoassay seems to be quite specific for this compound. Pretreatment of lungs with indomethacin (a non-selective inhibitor of cyclooxygenase) reduced 8-iso-prostaglandin F2alpha release under basal conditions and completely abolished the increase observed during lung anaphylaxis. Pretreatment of lungs with NS 398 (N-[2-cyclohexyl]-4-nitrophenyl methanesulphonamide), a selective inhibitor of cyclooxygenase-2, did not change basal or antigen-induced 8-iso-prostaglandin F2alpha release at all. We conclude that under basal conditions guinea-pig lung perfusates contain low levels of 8-iso-prostaglandin F2alpha-like immunoreactivity, which increase 10-fold during antigen-induced bronchoconstriction. This isoprostane seems to be derived from the cyclooxygenation of arachidonic acid via the constitutive form of cyclooxygenase.

Anaphylaxis↗
PubMed1999

Characterization of Ca(2+)-channels responsible for K(+)-evoked [(3)H]noradrenaline release from rat brain cortex synaptosomes and their response to amyotrophic lateral sclerosis IgGs.

The contribution of the different Ca(2+)-channel subtypes to the K(+)-evoked [(3)H]noradrenaline release from rat cerebral cortex synaptosomes has been investigated. In the same experimental model, it was also verified whether the calcium-mediated neurotransmitter release is influenced by IgGs purified from sera of seven patients affected by sporadic amyotrophic lateral sclerosis. Synaptosome treatment with 3.0 microM nifedipine or 2.0 microM calciseptine, which block L-type channels, slightly decreased [(3)H]noradrenaline release, the reduction being 7 and 13% of the control values, respectively. The blockade of N-type Ca(2+)-channels with omega-conotoxin-GVIA (0.001-1.0 microM) induced a concentration-dependent reduction of the neurotransmitter release, with maximum effect of 34%. omega-Agatoxin-IVA failed to significantly affect the studied release, which was instead markedly reduced by omega-conotoxin-MVIIC. After the blockade of N-type channels with maximal concentrations of omega-conotoxin-GVIA, 3.0 microM omega-conotoxin-MVIIC reduced the release by 58%. Synaptosome treatment with amyotrophic lateral sclerosis IgGs enhanced the K(+)-evoked [(3)H]noradrenaline release, which was mostly mediated by P/Q- and N-type Ca(2+)-channels. The increase induced by pathologic IgGs (0.2 mg/ml) ranged from 11 to 62% for the different patients, and it was concentration-dependent. The basal release was instead unaffected by IgG treatment. The results of the present study suggest that the K(+)-evoked [(3)H]noradrenaline release from brain cortex synaptosomes is mainly mediated by activation of P/Q- and N-type Ca(2+)-channels. Autoantibodies present in the sera of patients affected by sporadic amyotrophic lateral sclerosis may interact with these channels by producing an increased calcium influx, with consequent enhancement of the neurotransmitter release. Preliminary results of the present study have been published in abstract form (Martire et al., 1997, Pharmacol. Res. 35:9).

Animals↗
PubMed1999

No cardiovascular effects of single-dose pseudoephedrine in patients with essential hypertension treated with beta-blockers.

OBJECTIVE: The use of the decongestant pseudoephedrine has been cautioned in patients with arterial hypertension, due to the possible rise in blood pressure induced by the sympathostimulatory properties of the drug. This effect could be enhanced in hypertensives treated with beta-blockers, in whom the vasoconstrictor effect of alpha-adrenergic stimulation is unbalanced. The purpose of this study was to investigate the cardiovascular response to pseudoephedrine in hypertensive patients treated with different types of beta-blockers. METHODS: We recruited 29 (18 males) mild-to-moderate essential hypertensive patients [mean age 49(2) years] in a randomized, placebo-controlled, crossover trial. All participants received either placebo, or a nonselective (propranolol 160 mg once daily) or a selective (atenolol 100 mg once daily) beta-blocker for 1 week. At the end of each period, all patients received a single oral dose of pseudoephedrine (60 mg) and their blood pressure and heart rate were monitored at repeated intervals for 2 h. RESULTS: After 1 week of propranolol or atenolol, patients had significantly lower systolic blood pressure and heart rate than after placebo, whereas diastolic blood pressure was not significantly modified. The acute administration of pseudoephedrine did not change systolic and diastolic blood pressure and heart rate from baseline at the end of any of the treatment periods. CONCLUSIONS: A standard oral dose of pseudoephedrine does not significantly affect blood pressure values in hypertensive patients treated with beta-blockers, and therefore may be safely used in this subset of patients.

Adrenergic alpha-Agonists↗
PubMed1999

Breakfast type, daily nutrient intakes and vitamin and mineral status of French children, adolescents, and adults.

OBJECTIVE: To examine associations between the consumption of different types of breakfasts, dietary intakes, and selected indices of nutritional status. METHODS: Dietary intakes were obtained using the dietary history method, and serum bioassays were used to assess vitamin and mineral status in a representative community-based sample of 1108 French children (ages 2 to 10 years), adolescents (ages 10 to 18 years), and adults (ages 18 to 65 years). Breakfasts were divided into three categories: low-energy (<15% of the energy RDA), medium-energy (15-25%) and high-energy (>25%). RESULTS: High-energy breakfasts were associated with the consumption of ready-to-eat (RTE) cereals. High-energy breakfasts and cereal consumption, both more common among children and adolescents than among adults, were also associated with a greater proportion of daily energy from carbohydrate and lower proportion of energy from fat. High-energy breakfasts and cereal consumption were further associated with higher intakes of vitamins and minerals as measured by percent RDAs. High-energy breakfasts and cereal consumption were associated with lower serum cholesterols and improved biochemical indices of nutritional status. Serum concentrations of vitamin B1 (in children and adolescents), vitamin B2 and beta-carotene (in adults) were significantly linked to the level of energy provided by breakfast. CONCLUSION: The consumption of breakfast cereals appears to have a positive impact on nutritional status regardless of age.

Adolescent↗
PubMed1999

Prevalence of venous insufficiency in French adults of the SUVIMAX cohort. SUpplémentation en VItamines et Minéraux AntioXydants.

BACKGROUND: The symptoms of venous insufficiency of the lower limbs (VILL) include a feeling of heaviness in the legs, pain, and nocturnal cramps, which may be combined with organic disorders (varicose veins). The objective of this study was to determine the prevalence of VILL in terms of both varicose veins and functional symptoms in the participants of the SUVIMAX cohort, which is representative of the French population for the age range under consideration (women: 35-60; men: 45-60). METHODS: Information on the venous status of 3065 subjects in the SUVIMAX cohort were collected from three different sources: yearly systematic clinical examination (1994-1996), monthly follow-up by a telematic network (1994-1998) and non-specific questionnaire (1997). Two mutually exclusive populations were thus defined on medically diagnosed varicose veins and venous insufficiency and reported varicose veins and venous insufficiency. RESULTS: Venous insufficiency was medically diagnosed in 192 men (14.6%) and 584 women (33.6%), and varicose veins were diagnosed in 143 men (74.5%) and 317 women (54.2%) from this group. Prevalence reported symptoms of venous insufficiency and of varicose veins was 13.6% and 7.4% respectively in men and 28.2% and 12.4% in women. Sex, age, body mass index and number of pregnancies were found to be correlated with the risk of venous insufficiency. CONCLUSIONS: VILL is a very common disease in French adults both as varicose veins and as functional symptoms. Venotonics were the main type of treatment but not enough use is made of elastic compression stockings.

Adult↗
PubMed1998

Hypothalamic interleukin-1 in physiology and pathology.

The occurrence of interleukin-1 (IL-1) in the brain is usually associated with pathological events of the central nervous system (CNS), although there is evidence that the cytokine may also play a role in physiological processes. The ability of IL-1 to induce a damage in the CNS is dependent on the type of cell producing the cytokine and the length of exposure; on this regard, it is possible to distinguish between the minutes-to-days and the days-to-years time-frames. While the long-term action of IL-1 in the CNS is unambiguously associated with the activation of glial cells as well as the occurrence of chronic disorders such as Alzheimer's disease and AIDS-related dementia, it remains to be established whether glial cells, 'interleukinergic' neurons or both cell types are involved in CNS responses to acute noxiae, such as physical stress (restrain stress, nociceptive stimulation) or immune-inflammatory challenges.

AIDS Dementia Complex↗