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Biomedical subjects

M Lagos

Publications and source records attributed to M Lagos.

16 recordsLinked to original sources
PubMed2000

Elastic instability of grain boundaries and the physical origin of superplasticity

Matter between contiguous crystallites is assimilated to a thin elastic plate immersed in a different elastic medium. It is shown that a shear stress exceeding a critical value should corrugate the boundary and induce periodic normal stress fields in the two adjacent crystal surfaces, which cause motion of vacancies in closed loops between the two crystals. The consequent cyclic transport of atoms in the opposite sense determines crystal sliding at a temperature dependent relative speed. Most of the phenomenology of superplastic allows follows in a quantitative manner.

Journal Article↗
PubMed1999

[Our experience with 1 mg BCG vaccine instillation in T1 stage cancer of the bladder].

UNLABELLED: We studied 67 patients with bladder cancer in stage T1, with terminated BCG treatment and in pursuit. No stage Ta neither carcinoma in situ was included. The protocol was: beginning of treatment upon retiring vesical catheter, instilation of 1 mg of liofilized BCG vaccine (16 x 10(6) bacilles) in 40-50 ml of intravesical saline solution. A weekly instilation during the first month. An instilation each 15 days during the second and third month and one monthly until complete 12 months of treatment. Also was carried out an study of T lymphocites and cytokines. RESULTS: The average followup of the 67 patients treated was 51.3 months. 17 patients relapses (25.4%). A 33% were grade 3 and 27% grade 2. Like complications there was a case of inguinal TBC adenititis, 2 TBC prostatitis, 2 TBC cistitis and 5 cases of slight disuric syndrome. The study of subpopulations of lymphocites in peripheral blood demonstrated a significant increase of CD3 and CD4/CD8 ratio. The interleukin 2 measurement in serum also increased significantly after the BCG instilations. CONCLUSIONS: Our protocol gets similar results to the higher doses, but with minimal complications diminishing the relapses of the tumors in stage T1. A monthly maintenance dose would help to maintain immunity.

BCG Vaccine↗
PubMed1998

Plasma and platelet concentration and platelet uptake of serotonin in normal and pre-eclamptic pregnancies.

Pharmacologic and methodologic advances over the last decade have resulted in a body of information implicating serotonin as a mediator in the genesis of pre-eclamptic hypertension. Platelets contain the largest storage of serotonin in peripheral blood and have the ability to take up this amine from surroundings, store and release it by several mechanisms. Plasma and platelet serotonin concentrations and platelet serotonin uptake have been measured in 8 non-pregnant women, 12 normal pregnant women and 8 women with severe pre-eclampsia. Plasma serotonin concentration was significantly higher in severely preeclamptic women, compared with age and gestation matched normal pregnant women. In addition, plasma serotonin concentration was directly related to systolic and diastolic blood pressure with severity of the syndrome. Furthermore, platelet serotonin concentration in women with pre-eclampsia was significantly higher than in non-pregnant controls, but it was not significantly different from the normal pregnant women. Moreover, serotonin is effectively taken up by platelets through a saturable transport process. The calculated apparent Km for serotonin uptake process did not differ significantly among non-pregnant women, normal pregnant women and women with pre-eclampsia. However, Vmax values were significantly higher in women with pre-eclampsia than in the normotensive pregnant women. As the actions of serotonin in the periphery could be terminated primarily by active uptake system by platelets and placenta, significant alterations in the rate of transport could result in physiologically significant changes in serotonin levels. These data raise the possibility that abnormal regulation of transporter function is involved in the etiology of pre-eclampsia.

Adult↗
PubMed1995

Endothelial modulation of vascular tone and 5-hydroxytryptamine-induced responses in human chorionic arteries and veins.

1. In vitro studies were undertaken to evaluate the potential role of endothelium through release of vasodilators compounds on basal tension and on vasoconstrictor response induced by 5-hydroxytryptamine (5-HT) in chorionic arteries and veins rings from normotensive gestants. 2. N omega-nitro-L-arginine (100 microM) and methylene blue (10 microM) increased significantly the basal tension in chorionic arteries but not in veins. However, indomethacin (10 microM) inhibited the basal tension in both kinds of vessels. 3. The sensitivity to 5-HT was significantly lower in placental arteries than in veins. Removal of endothelium increased the sensitivity of placental arteries to 5-HT in 2.2-fold; however, in veins denudation had no significant effect. 4. N omega-nitro-L-arginine potentiated the 5-HT-induced tone in both types of vessels, but the increase of contraction was greater in chorionic arteries than in veins. However, indomethacin decreased the 5-HT-induced contractions in arteries and veins. 5. These results indicate that NO is more important than vasodilators prostanoids in the control of vascular tone and in 5-HT-induced placental contractile response.

Abortifacient Agents↗
PubMed1995

Nitric oxide and prostaglandin systems inhibition on the isolated perfused human placenta from normal and preeclamptic pregnancies.

Isolated human placental cotyledons from normal (NG) and preeclamptic gestants (PG) were perfused in vitro, and the effect of N omega-nitro-L-arginine (L-NA, 100 microM), methylene blue (MB, 50 microM), and indomethacin (INDO, 10 microM), on resting perfusion pressure and on the 5-hydroxytryptamine (5-HT)-induced vasoconstriction was established. In the HG, L-NA and MB increased resting perfusion pressure (p < 0.001) and INDO had no significant effect on resting pressure. In the PG, these agents did not significantly modify resting perfusion pressure. In the PG, 5-HT (10 microM-1 microM) caused greater maximal increases in perfusion pressure than in NG. In the NG, L-NA greatly enhanced the 5-HT-induced pressure, however INDO attenuated this effect. In the PG, L-NA did not modify significantly the 5-HT-induced response, but INDO reduced this response. These results suggest that basal release of nitric-oxide but not of vasodilator prostanoids may contribute to the low resting vascular tone in the NG and attenuates the strong vasoconstrictor effect induced by 5-HT. Impairment of action of nitric oxide could contribute to the enhanced pressor response to 5-HT observed in the PG.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1993

Venous placental reactivity to serotonin in normal and preeclamptic gestants.

The effect of serotonin (5-HT) on the contractile activity of venous chorionic rings from normal and preeclamptic gestants was analyzed. The results indicate that the resting tension did not differ between the groups, but the spontaneous rhythmic contractions began earlier and were of higher amplitude in the preeclamptic group. Dose-response data indicate that venous segments from preeclamptic patients developed a 1.7-fold increase in sensitivity to 5-HT. These effects were accompanied by an increase in maximal isometric tension (Emax) and relaxation times. Decreased desensitization and lack of tachyphylaxis was observed in most of the vascular preparations from the preeclamptic group. These data suggest that 5-HT may have a role in the modulation of preeclampsia.

Chorionic Villi↗