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To evaluate the prevalence of sexual activity and contraception methods used by Greek adolescents. To assess the effect of various factors in the decision making on sexual activity.A cross-sectional study design was applied. SETTING-PARTICIPANTS: The population (N = 1538) consisted of a random sample, stratified according to locality and population density, of 20 public junior high and high schools located in the urban district of Athens, Greece.Anonymous self-completed questionnaires were used to assess sexual practices, contraception methods, and factors affecting sexual activity choices.Spearman association calculations and chi-square were used, while regression analysis models were also applied.We examined the sexual practices among Greek adolescents, and indicated the psychosocial factors that may influence adolescents' sexual behavior.16% of the adolescents have had sexual intercourse, while the boy/girl ratio was 3/1 (P0.05). Mean age of sexual debut was 14 +/- 1.5 years. An additional 20% have had any other sexual experience at a mean age 13.5 +/- 1.5 years. Although sexually active adolescents generally use condoms (90.6%), only 32% use them properly (at every and throughout sexual contact). At least half of them do not have adequate protection (no method used or unreliable methods applied), while 8.2% of the girls have used emergency contraception. Adolescents with unstable home environment (divorce, recent death, not living with mother) or sexually experienced peers, as well as those that seek sexual education from siblings or friends have higher possibilities of being sexually active.Greek adolescents can be sexually active at a young age and they need sexual education on safe sex practices.

To investigate 24-hour ambulatory blood pressure, lipid profiles, and carotid artery intimal-medial thickness (IMT) in adolescents with and without obesity.Ambulatory blood pressure data from 93 consecutive adolescents referred to our hypertension center for possible hypertension were analyzed. Fasting serum glucose and lipid concentrations were measured in all subjects. Carotid artery IMT was also measured by B-mode ultrasound imaging in all patients. Obesity was defined as body mass indexor =95(th) percentile for age and sex. Twenty-two of the subjects were obese and 71 nonobese.Mean 24-hour, daytime, and nighttime systolic blood pressures were significantly higher in obese subjects compared with nonobese subjects (P.002). Twenty-four-hour, daytime, and nighttime pulse pressures were also significantly higher in obese subjects (P.001). The magnitude of systolic white coat effect was significantly higher in obese subjects (P.006) and white coat hypertension was significantly more frequent in obese subjects (P.0001). Obese subjects had higher triglycerides (P.001) and lower HDL cholesterol (P.01) than nonobese subjects. Finally, obese adolescents had thicker mean IMT of internal carotid arteries than nonobese adolescents (P.005).Obese adolescents have higher ambulatory blood pressure and higher carotid artery IMT, possibly indicating an early course of obesity-related hypertension and carotid artery structural alterations.

The role of cyclic adenosine 3′,5′-monophosphate (cAMP) in the regulation of rat liver bilirubin uridine diphosphate glucuronyltransferase (UDP-GT) was studied. Augmentation of UDP-GT activity was obtained by cAMP, but not by 3′-AMP. A single administration of glucagon initiated a rapid but limited increase in enzyme activity, which reached a maximum after 2 hr. Similar augmentation of the hepatic enzyme was produced by injection of N 6 ,O 2 -dibutyryl cAMP. The nucleotide is the mediator for UDP-GT augmentation by glucagon. The injection of glucagon led within 20 min to a 40-fold increase in the concentration of cAMP. The augmentation of UDP-GT activity by glucagon or dibutyryl cAMP was fully inhibited by actinomycin D. A second stimulation of liver by glucagon or dibutyryl cAMP 4 hr after the first injection, produced a new increase of UDP-GT activity.

Intra-adrenal ascorbic acid (AsA) concentrations exert a braking or modulating effect upon steroid release. Because changes in steroidogenesis are mediated through alterations in adenylate cyclase activity (ACL), the effect of varied AsA plasma concentrations on guinea pig adrenal ACL activity and plasma cortisol was studied. Forty-two male guinea pigs were randomly allocated to the following seven groups: controls, scorbutic, and groups given 0.1, 5, 10, 20 or 100 mg ascorbic acid/100 g body weight, respectively. Scorbutic animals had very low levels of AsA in comparison to control animals. Plasma AsA levels increased as AsA dose increased. The levels of AsA in the group given 0.1 mg AsA were higher than in controls. Basal adenylate cyclase activity did not vary significantly among animal groups. In contrast, values for NaF-stimulated ACL activity showed a progressive decrease with increasing AsA doses. A highly significant correlation was found between decreasing ACL activity and increasing plasma AsA concentrations. On the other hand, NaF-responsive ACL activity was higher in scorbutic animals than in any other group. Higher mean cortisol values were found in the scorbutic group than in the controls, correlating with high levels of NAF-stimulated ACL activity. Higher mean cortisol values were also found in the group given 0.1 mg AsA although ACL activity in this group was not affected. This finding, coupled with reduced ACL activity in these groups, is consistent with the inhibitory effect of a megadose of AsA on production of cortisol from the adrenal. The above data may suggest that differing plasma concentrations of AsA regulate in vivo steroidogenesis by altering the activity of the membrane-bound enzyme adenylate cyclase.

Summary The phagocytosis stimulating peptide present in γ-globulin has been isolated and its amino acid sequence shown to be L-threonyl-L-lysyl-L-prolyl-L-arginine. It was synthesized by the solid phase technic.

Membrane adenylate cyclase (AC) from polymorphonuclear (PMN) leucocytes and platelet membranes are activated several fold by fluoride and prostaglandin E1 (PGE1) respectively. Incubation of such activated membranes in a phosphorylating system inhibits cyclase activity. The inhibition can now be relieved by further treatment with fluoride and PGE1 respectively. These findings suggest that AC exists in an inhibited phospho- and activated dephospho-form. This is supported by the finding that membrane preparations from both sources contain a cyclic adenylate (cAMP) stimulated protein kinase and points to the existence of an adequate membrane phosphorylating system.

The presence of sialic acid on the polymorphonuclear (PMN) phagocyte is necessary for maximal stimulation of its phagocytic activity by the tetrapeptide, tuftsin, Thr-Lys-Pro-Arg. Treatment of polymorphonuclear cells with bacterial neuraminidases, purified by affinity chromatography, completely abolishes stimulation of phagocytic activity by free tuftsin or by tuftsin bound to the carrier leukokinin molecule. These enzymes cleave sialic acid at both 2-3' and 2-6' glycosidic bonds. By contrast, treatment of cells with influenza virus neuraminidase, which cleaves predominantly the 2-3' linkage, reduces the tuftsin effect by approximately 50%. Enzyme-treated cells remain viable and capable of phagocytosis. Cells treated with any of the neuraminidases and cells of the untreated controls show comparable levels of phagocytosis in the absence of tuftsin. While membrane sialic acid is necessary for stimulation of phagocytosis, it may function only as a binding site for the three positively charged residues of the tetrapeptide. Neuraminidases from Vibrio cholerae or Clostridium perfringens, in excess amounts, released in 2 hours a maximum of about 135 million molecules of sialic acid per polymorphonuclear cell. Under similar conditions, treatment with influenza virus released approximately 30 million molecules per cell.