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Biomedical subjects

M Orlandi

Publications and source records attributed to M Orlandi.

At least 37 records · Page 2Linked to original sources
PubMed1995

School policy in COMMIT: a promising strategy to reduce smoking by youth.

Organizational smoking policy has been identified as a potentially effective way to influence health behavior, particularly in worksites. Examining the elements of existing school smoking policies for both students and employees can provide insight into the potential effectiveness of these policies in changing young people's smoking behavior. This paper examines selected components of existing school smoking policies in a national sample of schools at all levels of education as part of the Community Intervention Trial for Smoking Cessation. Schools were questioned about their school smoking policies, related resources, and compliance. The data show much variation in the elements of school tobacco use policy to change smoking behavior. Existing policies in schools differ among grade levels, thus providing different messages about the appropriateness of smoking. Policies differ for students and adults, providing another opportunity for confusion about the messages that policy can deliver. In general, resources available to support existing policies are lacking. Many schools offer classes on knowledge of negative health effects of smoking but do not teach the psychosocial skills necessary to resist tobacco use. In its present forms, school policy has great potential for an effective tool for health promotion, but considerable reform is needed to overcome current barriers.

Adolescent↗
PubMed1995

Possible involvement of prostaglandin H synthase-1 induction in the differentiation of U-937 cells.

The promyelocytic human cell line U937, cultured in the presence of TPA and/or vit. D3, differentiates to monocytes and to macrophage-like cells. A potent stimulus for differentiation is represented also by colony stimulating factor-1 (CSF-1). Since this factor is a strong inducer of PGH synthase in human monocytes, we have investigated whether this event may be connected to the differentiation of U937. We have found that TPA, in the presence of serum, increased the production of thromboxane B2 (TXB2) 4-5 fold, while DMSO, which induced differentiation to neutrophils, was not active. Here we report studies indicating that the effect of protein and RNA synthesis inhibitors on prostanoid production, in cells incubated in the presence of CSF-1 (or FCS), can be correlated with an inductive event carried out by the growth factor, as demonstrated by the use of Western and Northern blotting procedures. However, while in human monocytes PGH-s and its mRNA are absent in controls and are expressed at high levels in CSF-1 stimulated cells, in U937 cells exposed to TPA, PGH-s mRNA was clearly detected by Northern blots, but its translation product was expressed at low level, and cells generated low amounts of TXA2 (13% of maximal production). After incubation with CSF-1 (or FCS) mRNA levels were only slightly modified, but large amounts of TXA2 accumulated in the medium. We have interpreted these findings by suggesting that CSF-1 is capable not only of regulating the expression of the gene encoding PGHs, but also of acing translationally to regulate the expression of its mature mRNA.

Blotting, Western↗
PubMed1994

Thromboxane A2 synthase activity in platelet free human monocytes.

Soon after platelets, the highest amounts of thromboxane A2 (TXA2) can be detected in human monocytes activated by serum. Using platelet-free human monocytes, we have shown that foetal calf serum (FCS) induces prostaglandin H synthase (PGH synthase) after 16 h of incubation, as shown by the use of transcriptional inhibitors and Western blotting. The effect of serum can be in part mimicked by recombinant colony stimulating factor-1 (hr CSF-1). It is not known whether the limiting step leading from arachidonate to TXA2 is represented solely by the level of PGH synthase or also by the level of TXA2 synthase. We approached this problem by using a Western blot specific for the enzyme, as well as by using PGH2 as substrate. The results show that TXA2 synthase is constitutively expressed in monocytes, i.e., its levels were high soon after their isolation, and similar to those observed after 24 h of incubation with serum. However TXA2 failed to be synthesized until at least 3 h of incubation, and the pattern of synthesis was dependent on the kinetics of PGH synthase induction. In any condition in which TXA2 synthase was immunodetectable, using PGH2 as substrate a high rate of conversion to TXB2 could be detected. Experiments with actinomycin D and cycloheximide indicate that the half-life of TXA2 synthase was longer than 16 h, therefore much longer than that of PGH synthase, that the gene coding for it is fully active in resting monocytes, and that the conversion of arachidonate to TXA2 induced by serum or CSF-1 is dependent solely on the de novo synthesis of PGH synthase.

Apoenzymes↗
PubMed1994

Allosteric modulation of [35S]TBPS-binding in the cerebral cortex of the rat during postnatal development.

The ontogenesis of the GABA-gated Cl- channel was investigated in the cerebral cortex of the rat by monitoring the binding parameters of [35S]t-butylbicyclophosphorothionate ([35S]TBPS) at intervals after birth (1-90 days). To investigate the influence of the developmental changes in the content of GABA on [35S]TBPS-binding, the assays were carried out in unwashed membranes, in which the concentration of GABA was dependent on its content in vivo, and in repeatedly washed membranes in the presence of defined concentrations of exogenous GABA. At birth, the density (Bmax) of [35S]TBPS-binding sites in unwashed membranes was similar to that found in well-washed membranes. However, in unwashed membranes, the number of [35S]TBPS-binding sites increased by two-fold within 10 days after birth whereas in washed membranes it increased by four-fold during the same period. The higher density of [35S]TBPS-binding sites in washed membranes as compared with the unwashed counterparts persisted throughout development. In unwashed membranes, the apparent Kd for [35S]TBPS-binding increased with age whereas in washed membranes the affinity of [35S]TBPS for its binding sites remained constant throughout development. The binding of [35S]TBPS to the GABA-gated Cl- channel is allosterically modulated by drugs acting on different sites of the GABAA receptor complex. Thus, GABA and diazepam decrease [35S]TBPS-binding whereas the GABAA receptor antagonist, bicuculline, and the inverse agonist for benzodiazepine receptors, 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylic acid methyl ester, increase it.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1994

GABAergic and dopaminergic transmission in the brain of Roman high-avoidance and Roman low-avoidance rats.

The GABAergic and dopaminergic pathways in the central nervous system (CNS) play a pivotal role in the control of emotions and in the adaptive responses to stressful stimuli. The present study was aimed at characterizing a range of biochemical markers of GABA- and dopamine-mediated neurotransmission in the CNS of Roman high-avoidance (RHA/Verh) and Roman low-avoidance (RLA/Verh) rats, two psychogenetically selected lines that differ in their level of emotionality. The stimulatory effect of GABA on 36Cl- uptake was less pronounced in the cerebral cortex of RLA/Verh rats as compared to RHA/Verh rats, whereas no line-related changes were detected in [3H]GABA and [3H]flunitrazepam binding. On the other hand, the density of D1 dopamine receptors labeled with [3H]SCH 23390 was lower in the nucleus accumbens of RLA/Verh rats as compared to their RHA/Verh counterparts, whilst no line-dependent changes were observed in the binding parameters of D1 dopamine receptors in the striatum, amygdala, and prefrontal cortex. These biochemical differences may contribute to the distinct emotionality and responsiveness to the effects of psychoactive drugs of RHA/Verh and RLA/Verh rats.

Amygdala↗
PubMed1994

Prognostic significance of serum lactate dehydrogenase in patients with osteosarcoma of the extremities.

Six hundred and fifty-six patients with osteosarcoma of the extremities (107 metastatic and 549 with localized disease) were followed from 2.5 to 20 years (average: 10 years) to evaluate whether their pretreatment serum lactate dehydrogenase (LDH) enzyme levels had a clinical value in predicting the course of the disease. The percentage of patients who had an elevated serum LDH at the time of diagnosis was significantly higher in those patients with metastatic disease than those who had localized disease (64% versus 33%, p < 0.0001). For those who presented with localized disease and had an increased serum LDH level, far more ultimately developed a relapse of disease (60% versus 38%, p < 0.0001) than those patients with a normal pre-treatment value. The prognostic significance of the serum LDH was more pronounced for the 247 patients treated with adjuvant chemotherapy (relapse rate of 72% versus 48%; p < 0.0002) than the 271 patients treated with neoadjuvant chemotherapy (relapse rate: 46% versus 28%, p < 0.005). Following treatment, serum LDH levels almost uniformly returned to normal and no correlation between postoperative levels and relapse of disease could be identified. We have demonstrated that in patients with osteosarcoma of the extremities, pretreatment serum LDH levels have a definite prognostic value which should be considered when comparing the results achieved with different therapeutic protocols and in planning new randomized clinical trials.

Adolescent↗
PubMed1993

Prognostic significance of serum alkaline phosphatase measurements in patients with osteosarcoma treated with adjuvant or neoadjuvant chemotherapy.

BACKGROUND: It is known that many patients with osteosarcoma have high serum alkaline phosphatase (SAP) levels. The prognostic significance of this finding, however, is still controversial. METHODS: The pretreatment SAP levels of 656 patients with osteosarcoma of the extremities (107 metastatic and 549 localized at presentation) were examined to evaluate whether the enzyme levels had a clinical value in predicting the course of the disease. RESULTS: The percentage of patients with increased SAP levels was significantly higher in the metastatic group than in the group of patients with localized disease (91.5% versus 61.3%; P < 0.001). In the latter group, treated with adjuvant and neoadjuvant chemotherapy, the relapse rate was significantly higher in patients with elevated pretreatment SAP levels than in those with normal levels (55.1% versus 26.4%; P < 0.001). Among patients with elevated SAP levels, the percentage of relapses was higher in patients with high levels of the enzyme in comparison with patients with moderately elevated values (66.4% versus 47%; P < 0.05). After treatment, SAP levels almost always return to normal values, and a correlation between postoperative levels of the enzyme and prognosis could not be made. CONCLUSIONS: These data demonstrate that in osteosarcoma of the extremities, pretreatment SAP levels have a prognostic value and they should be considered when comparing the results achieved with different therapeutic protocols and in planning new randomized clinical trials.

Adult↗
PubMed1993

Serum methotrexate (MTX) concentrations and prognosis in patients with osteosarcoma of the extremities treated with a multidrug neoadjuvant regimen.

The relationship between the serum concentration of methotrexate and the prognosis has been studied in 108 patients with osteosarcoma of the extremities treated from September 1986 to December 1989 at the Chemotherapy Department of Rizzoli Hospital. The protocol of neoadjuvant chemotherapy included high doses of methotrexate (HDMTX) adriamycin, cisplatinum, ifosfamide and VP-16. After a median follow-up of 40.4 months (range 24-62), 84 (77.7%) of the patients studied remained continuously disease-free (CDF) and 24 relapsed. Significantly higher mean serum MTX concentrations were observed in the patients who remained CDF (669.5 mumol/l) than in the patients who relapsed (571.9 mumol/l) (p < .004). The breaking point of prognostic significance for the serum MTX levels seems to be 700 mumol/l. In fact, according to the mean MTX concentrations, the patients with less than 700 mumol/l showed a significantly lower disease-free survival than the patients with higher mean MTX concentrations (68.12% vs 94.87% p < .0013). The distribution of prognostic variables between the two groups was the same in terms of site and histological type of tumor and alkaline phosphatase serum levels at diagnosis. In the group which had more than 700 mumol/l MTX, a higher percentage of good histological response after primary chemotherapy was observed. This is probably independent from the MTX because no significant preoperative MTX serum levels between good and partially responding patients were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

In vitro and ex vivo evaluation of methotrexate removal by different sorbents haemoperfusion.

The administration of high doses of Methotrexate (HDMTX) seems to be very effective in neoplastic treatment. Furthermore high doses of the drug could overcome the Methotrexate (MTX) resistance that it is possible to observe in some kind of cancers. To avoid several serious problems in the therapeutical application of HDMTX such as nephrotoxicity, hepatotoxicity and the difficulty to assess the right therapeutic range of the specific antagonist Leucovorin, a Haemoperfusion (HP) treatment could be very usefulL. In this study 3 anion exchange resins with different active group (trimethylammonium, dimethylethanolammonium and dimethylammina) and a spherical petroleum based charcoal were tested both in vitro and ex vivo to evaluate their capability to remove MTX. These results show a good strength and biocompatibility of the 4 sorbents and demonstrate the active group trimethylammonium resin as the most effective one.

Adsorption↗
PubMed1993

Monitoring during haemoperfusion (HP).

The relationship between HP and haemodynamic changes is an area which until now has been largely uninvestigated as can be seen from the small amount of material published on this theme. The reasons for this indifference are mainly due to the low extracorporeal flow using during HP. The experiment with a new sorbent on animals must also be analyzed in cardiovascular aspects. This system is the most economical and simple for detecting the elution of vasoactive toxins. In this report the effect on the cardiovascular system of HDMTX and HP with a new trimethylammonium exchange resin versus control groups are evaluated. The results obtained clearly demonstrate the absence of haemodynamic side effects in both groups.

Animals↗
PubMed1993

[Prevention of post-ovariectomy osteoporosis in the rat. Comparative study of synthetic salmon calcitonin and eel calcitonin aminosuberic analogue].

The authors evaluate the efficacy of salmon calcitonin and aminosuberic analogue of eel calcitonin in the prevention of post-oophorectomy osteoporosis in rats. Both drugs, administered at the same dosage, are equally effective in preventing oophorectomy bone loss in rats. Besides, plasma biochemical evaluations demonstrate that calcitonins reduce bone turnover in treated rats, compared with control oophorectomized ones.

Absorptiometry, Photon↗
PubMed1992

Substance use among Hispanic and non-Hispanic adolescents.

This study compared lifetime prevalence data on substance use with demographic and psychosocial variables among 2,821 Hispanic and non-Hispanic white students from two Southwestern cities. Study findings revealed that ethnic-racial background factors were not the strongest predictors of substance use. Rather, when the analyses accounted for school grades and for maternal education, non-Hispanic youth had higher lifetime substance use rates than Hispanic youth. Study findings suggest that preventive intervention and treatment efforts for substance abuse problems among adolescents should consider sociodemographic risk factors as well as ethnic-racial factors.

Adolescent↗
PubMed1992

Decrease in GABAergic function induced by pentylenetetrazol kindling in rats: antagonism by MK-801.

The role of tau-aminobutyric acid (GABA)A receptors and of the N-methyl-D-aspartate (NMDA) subtype of excitatory amino acid receptors was studied in the pentylenetetrazol (PTZ) kindling model. The repeated administration of subconvulsant doses of PTZ (30 mg/kg i.p., 3 times a week for up to 10 weeks) produced chemical kindling in 80% of rats under treatment. PTZ kindling was associated with a decrease in GABA-mediated inhibition in the central nervous system. Thus, the binding of [3H]GABA, the binding of 35S-t-butylbicyclophosphorothionate and the GABA-stimulated uptake of 36Cl- were significantly decreased in the cerebral cortex of PTZ-kindled rats as compared with control rats chronically treated with saline. Moreover, PTZ-kindled rats showed a persistent increase in the sensitivity to the convulsant action of different GABA function inhibitors, such as isonicotinic acid hydrazide (120 mg/kg s.c.), picrotoxin (1.5 mg/kg i.p.), bicuculline (1.3 mg/kg s.c.), FG 7142 (N-methyl-beta-carboline-3-carboxamide; 20 mg/kg i.p.) and Ro 15-4513 (ethyl-8-azido-5,6-dihydro-5-methyl-6-oxo-4H- imidazo-(1,5-a) (1,4)-benzodiaze pine-3-carboxylate; 20 mg/kg i.p.). The pretreatment with the noncompetitive NMDA receptor antagonist, MK-801 [(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d] cyclohepten-5,10-imine maleate; 0.1-1.0 mg/kg i.p., 40 min before each injection of PTZ], prevented in a concentration-dependent manner the development of kindling and the increase in the responsiveness to the convulsant effects of GABA function inhibitors observed in PTZ-kindled rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Effects of hydration on plasma concentrations of methotrexate in patients with osteosarcoma treated with high doses of methotrexate].

High dose of methotrexate (HDMTX) with leucovorin rescue requires over-hydratation to avoid nephrotoxicity; nevertheless the relationship between hydratation and plasma MTX levels is unknown. We compared the effects of two different types of hydratation (2 lt/m2 vs 1.5 lt/m2) on plasma MTX levels in two groups of patients with osteosarcoma of the extremities and treated with HDMTX (8 g/m2 IV). Samples were obtained at the end of infusion of MTX and 14 and 38 hours after the start of MTX infusion. At the end of infusion of MTX the medium plasma MTX levels proved significantly higher in the group with low hydratation than in the group with high hydratation (585.5 microns/l vs 427.7 microns/l P less than 0.001). The values obtained at 14 and 38 hours, did not show significant differences. No significant differences were seen between the two groups in term of late elimination of MTX and correlated toxicity. These data show that a low hydratation regime allows higher plasma MTX levels at the end of infusion of HDMTX and does not increase the incidence of late elimination of MTX compared to a high hydratation regime.

Adult↗
PubMed1991

Age-related decrease in the density of benzodiazepine recognition sites in the brain of the fresh water eel (Anguilla anguilla).

The binding parameters of benzodiazepine receptors labeled with [3H]flunitrazepam were investigated in the brain of male adult eels at the trophic phase (4 years old) and of male silver eels (6 year old ocean migrants). The density of [3H]flunitrazepam binding sites was significantly decreased (-26%) in the brain of silver eels compared with younger counterparts. In contrast, the apparent dissociation constant (Kd) was not significantly different in the two experimental groups. These results are discussed in terms of the possible involvement of stress, behavioral and environmental factors and age-related degenerative processes.

Aging↗
PubMed1991

MK-801 prevents chemical kindling induced by pentylenetetrazol in rats.

The repeated administration of pentylenetetrazol (PTZ) at a subconvulsant dose (30 mg/kg i.p., three times a week for nine weeks) produced kindling in 90% of rats under treatment. Pretreatment with the N-methyl-D-aspartate receptor antagonist, MK-801 (1 mg/kg i.p., 40 min before PTZ), prevented the behavioral manifestation (i.e. motor seizures) as well as the development of kindling. In fact, convulsions were not observed in rats pretreated with MK-801 either during the chronic PTZ administration or when challenged with PTZ three and 10 days after completion of the chronic treatment. The results suggest an involvement of excitatory amino acid neurotransmission in PTZ kindling.

Amino Acids↗
PubMed1991

Pentylenetetrazol-induced kindling in rats: effect of GABA function inhibitors.

The repeated administration of subconvulsant doses of pentylenetetrazol (PTZ) produced a progressive sensitization to the effects of this compound (i.e., chemical kindling) in the rat. A very similar time-course for PTZ-induced kindling was observed using two different treatment schedules: 1) one injection every day (30 mg/kg, IP), and 2) one injection (30 mg/kg, IP) every second day. When these treatment schedules were used for eight consecutive weeks, more than 80% of the rats displayed convulsions by the end of treatment. In contrast, only 20% of the rats were sensitized if PTZ was administered twice daily at the dose of 15 mg/kg, IP. The increased sensitivity to the convulsant effect of PTZ was still present one year after completion of the chronic treatment. Moreover, rats kindled with PTZ showed an enhanced susceptibility to convulsions induced by different inhibitors of central GABAergic function, such as the chloride channel blocker picrotoxin, the benzodiazepine receptor ligands FG 7142 and Ro 15-4513, and the inhibitor of GABA synthesis isoniazid. In contrast, the sensitivity to the convulsant action of the glycine receptor antagonist strychnine was unchanged by repeated PTZ administration. It is suggested that kindling produced by PTZ may be associated with a persistent reduction in the inhibitory function of the GABAergic system in the brain.

Animals↗