Biomedical subjects

M Venza

Publications and source records attributed to M Venza.

10 recordsLinked to original sources

PubMed2002

Age-related salivary polyamine increase in adolescents wearing orthodontic Ni-Ti archwires.

Until now information about the influence of puberty on gingival tissue responses to Ni-Ti alloy haven't been available. Since our previous researches have demonstrated that Ni-Ti appliances have an influence on hyperplastic gingivopathy and data has pointed out a possible hormonal influence on the susceptibility of gingival tissue to mechanical stress, we have attempted to study the relationship between fertility hormones and the periodontal response to Ni-Ti appliances. Three groups, ranging from 6 to 17 years old, were tested for salivary polyamine concentrations and for fertility hormone levels 12 months after Ni-Ti application. Results obtained from Pearson's correlation coefficient between polyamine and sexual hormone concentrations, as well as gingival and plaque indexes, suggest that the adolescent gingival tissue undergoes an hyperplastic process after long-term use of Ni-Ti appliances in relation to the puberty age-restricted peak of fertility hormones.

Adolescent↗

PubMed2001

Determination of polyamines in human saliva by high-performance liquid chromatography with fluorescence detection.

A high-performance liquid chromatographic method for the determination of polyamines (spermine, spermidine and putrescine) in human saliva was developed. This method is based on pre-column derivatization with o-phthaldialdehyde (OPA). The derivatives were separated on a Nucleosil ODS column (250x4.6 mm I.D.; 5 microm). The gradient elution was performed with two mobile phases A (water) and B (methanol) at a flow rate of 0.8 ml/min. The column eluate was monitored by fluorescence detection (excitation, 360 nm; emission, 510 nm). The within- and between-assay coefficients of variation for all the compounds were below 5%. The detection limits for spermine, spermidine and putrescine were 0.04, 0.05 and 0.06 nmol/ml, respectively. The recovery was greater than 90%. Our analytical technique requires neither preliminary extraction with an organic solvent, nor long multi-step procedures. For saliva samples, this is a simple, rapid and highly reproducible method that can be easily applied to the routine determination of salivary polyamines, whose levels increase early in several pathological conditions.

Biogenic Polyamines↗

PubMed2000

Polyamine metabolism in prostaglandin E2-treated human T lymphocytes.

The effects of Prostaglandin (PG) E2 treatment of human T lymphocytes on polyamine metabolism were investigated. PGE2 is known to inhibit lymphocyte proliferation, while polyamines play an important role in several biochemical processes leading to increased cell growth. Preincubation of T lymphocytes with PGE2 (10(-6) M) for 10 min was able to increase ornithine decarboxylase (ODC) activity and putrescine as well as spermine levels, while spermidine concentration was drastically reduced. After 30 and 60 min of treatment, a decrease in ODC activity and putrescine concentration was observed. On the contrary, the initial inhibition of spermine-N1-acetyltransferase (SAT) activity was followed by a progressive increase of this catabolic enzyme. These changes were related to modifications of cAMP concentrations. Our data may help clarify the mechanisms underlying the biphasic effect of PGE2, which ultimately leads to inhibition of cell proliferation.

Acetyltransferases↗

PubMed2000

Effects of vitamin E and prostaglandin E2 on expression of CREB1 and CREB2 proteins by human T lymphocytes.

Both prostaglandins (PGs) and vitamin E are known to deeply affect immune responses. It is shown here that they both influence T cell-mediated immunity through reciprocal interference on the expression of cyclic-AMP responsive element binding (CREB) family proteins. CREB1 protein of human T lymphocytes was significantly modulated by a brief treatment of 5 to 10 min with PGE2. On the contrary, vitamin E appeared to be ineffective on the CREB1 behavior, while it abolished the PGE2-induced modulation of this protein. The CREB2 protein expression was also affected by PGE2 treatment, but a longer period of incubation (>20 min) was needed to observe these changes. Vitamin E showed a strong enhancing effect on CREB2 that was partially reversed by the subsequent treatment with PGE2. Our results support the idea that there is reciprocal interference between PGE2 and vitamin E on PGE2-induced signals in T lymphocytes. These data are in agreement with the reports concerning different cell systems and experimental conditions.

Activating Transcription Factor 4↗

PubMed1998

Resistance to PGE2 inhibition of PWM-stimulated lymphocytes from neoplastic patients.

PGE2 treatment of mononuclear cells from patients with different types of neoplasias was unable to decrease either the number of plaque-forming cells or the expression of CD71 and CD25 in PWM-driven cultures. In contrast, in previous studies, PGE2 inhibited these parameters in cultured mononuclear cells from normal volunteers. Surgical treatment of cancer patients did not modify the lymphocyte sensitivity to PGE2 after 1 week, but at 2 and 6 months after therapeutical treatment, the inhibition values of the parameters studied were almost similar or very similar to those of normal lymphocytes. The reduction of PGE2 sensitivity in cancer patients was related to the increase of PGE2 levels and, probably, to a PGE2 receptor saturation. A restoration of PGE2-induced inhibition some months after therapy could be due to the decrease in PGE2 levels and to receptor unsaturation.

Antigens, CD↗

PubMed1996

Prostaglandin E2 induction of binding activity to CRE and AP-2 elements in human T lymphocytes.

Prostaglandins of the E series are immunomodulatory agents which exert inhibitory as well as stimulatory effects on a variety of immune responses. Since it is known that PGE2 is able to increase cAMP levels, we investigated whether it can affect gene expression through the activation of the transcription factors which bind enhancer elements in the promoter regions of cAMP-regulated genes. Using electrophoretic mobility shift assay, we demonstrated that a short treatment of human T lymphocytes with PGE2 induces specific binding activity to CRE and AP-2, but not AP-1, DNA elements. Since the okadaic acid, a potent protein phosphatase inhibitor, prolongs the induction of the binding activity, phosphorylation events are likely to occur. This activity seems to be due to increased cAMP levels because forskolin and IBMX mimic the effects of PGE2. More interestingly, transfection experiments with CRE-CAT plasmide show that PGE2 activates the transcription of a CRE-containing promoter. These data support the positive role for PGE2 on some immune functions.

1-Methyl-3-isobutylxanthine↗

PubMed1996

PGE2-induced immunoregulation mediated by cytokine production from cultures of human peripheral T lymphocytes.

Prostaglandins (PGs) are generally known to exert inhibitory as well as some enhancing effects on the immune system. This study was performed to assess the influence of the exogenous PGs and cyclic adenosine monophosphate (cAMP)-elevating agents on cytokine production by PWM-stimulated human T lymphocytes. Peripheral blood T lymphocytes from healthy donors were pretreated for 30 min at 25 degrees C with PGE2 (10(-4) to 10(-7) M) PGF1 alpha, IBMX or Forskolin (10(-4) to 10(-5) M) and cultured for 7 days in the presence of Pokeweed Mitogen (PWM), PGE2, IBMX and Forskolin, but not PGF1 alpha, significantly increased IL-6 production while inhibited IL-2, IL-3, IL-4, IFN-gamma, TNF-alpha and GM-CSF production. Our data indicate that cAMP-elevating agents can profoundly affect cytokine secretion by T cells in PWM-driven cultures and that this effect is dose-dependent. The results reported here are compatible with the existence of separate pathways of gene induction for IL-2, IL-3, IL-4, IFN-gamma, TNF-alpha and GM-CSF on the one hand and IL-6 on the other one.

Adjuvants, Immunologic↗

PubMed1995

Prostaglandins affect the respiratory burst of human neutrophils.

The effects of prostaglandins on superoxide generation by neutrophils were investigated, since these arachidonic acid metabolites are both involved in the early phase of the inflammatory process and during later stages of neutrophil function. Preincubation of these cells for five minutes with concentrations of PGE2 ranging from 10(-7) to 10(-4) M was able to significantly reduce superoxide production in PMA-stimulated neutrophils. Other pro-inflammatory PGs tested, such as PGE1, PGF1 alpha, PGF2 alpha, inhibited the respiratory burst. The PGE2-induced inhibition was compared to that exerted by staurosporine, a PKC inhibitor. The effects of the two drugs were not additive, since the combinations of PGE2 and staurosporine reduced O2- production to the same extent as staurosporine alone. Possible interferences between PKA- and PKC-mediated transduction signals are discussed.

Alkaloids↗

PubMedDate not supplied

Ameloblast morphogenesis during amelogenesis. S.E.M. study.

A study has been carried out on the S.E.M. on the enamel of an albino rat's inferior incisor. The observations concern almost the entire ameloblastic cycle, specifically, from the end of the cellular differentiation phase (pre-ameloblasts III) to the end of the modulation phase. The authors have pointed out some morphogenetical variations which during the depositing phase, are manifested on the distal extremity of the cells and are concentrated at this level in the differentiation of the Tomes' processes. Successively, during the transitional post-secretory and cellular modulation phases, the morphogenetical differences at the distal extremities also involve the lateral walls of the ameloblasts and their spatial relationships. Some morphological differences are correlated with different functional moments and revealed by an examination of the corresponding superficial areas of the enamel in the course of its formation. In this study, the constant orientation of the perpendicular is evident at the secretion plane in opposition with other studies that propose a 'pendulum movement' theory of these cells during the depositing phase of the prismatic layers. In addition, a morphological classification is proposed consisting of four types of modulative ameloblasts.

Ameloblasts↗

PubMedDate not supplied

Impairment of lymphocyte sensitivity to prostaglandin E2 in cultures from patients with lymphoadenopathy associated syndrome.

Prostaglandin E2 (PGE2) appears to have an immunosuppressive role in human immunodeficiency virus (HIV) infection. Therefore, the effect was studied of PGE2 pretreatment of T lymphocytes from patients with lymphadenopathy associated syndrome (LAS) on the expression of CD25 and CD71 as well as plaque forming cell (PFC) generation in pokeweed mitogen (PWM)-driven cultures. The PGE2-treated or untreated T lymphocytes were cultured with B cells and monocytes in the presence of PWM. Both CD25 and CD71 expression were assessed with an immunofluorescence technique; PFC generation was tested by hemolysis. Before exposure to PWM, LAS lymphocytes showed activation as evidenced by high CD25 and CD71 expression and PFC generation. Pretreatment by PGE2 did not inhibit expression of activation markers and PFC generation in LAS cultures, in contrast to what happened in control cultures. Thus, LAS lymphocytes are activated in vivo and are less sensitive to PGE2 inhibition than normal lymphocytes.

AIDS-Related Complex↗