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Biomedical subjects

A Foradori

Publications and source records attributed to A Foradori.

At least 55 records · Page 3Linked to original sources
PubMed1986

Response of the maternal, fetal, and neonatal pituitary-thyroid axis to thyrotropin-releasing hormone.

Thyrotropin releasing hormone (TRH) readily crosses the placenta and stimulates the fetal pituitary. We studied the response of the maternal and fetal pituitary-thyroid axes to TRH and the influence of prenatal exposure to TRH on the physiological postnatal increase in thyrotropin (TSH) and triiodothyronine (T3) in the neonate. Twenty-six pregnant women received TRH (400 or 600 micrograms) intravenous or saline (controls) either 2 or 12 h before elective cesarean section at term. Administration of 400 micrograms of TRH resulted in significant elevations of maternal TSH (15.7 +/- 2.9 versus 3.2 +/- 0.4 microU/ml, p less than 0.01) and prolactin (416 +/- 94 versus 223 +/- 41 ng/ml, p less than 0.05) 2 h later. Maternal T3 remained unchanged. A higher dose of TRH (600 micrograms) produced comparable results. Maternal administration of TRH (400 micrograms) 2 h before delivery resulted in significant increases in fetal TSH and T3 over controls (21.1 +/- 3.7 versus 4.8 +/- 1.0 microU/ml, and 132 +/- 12 versus 64 +/- 9 ng/dl, p less than 0.01, respectively). Cord blood hormone levels 12 hours after TRH administration were similar to controls. Higher doses of TRH did not produce further increases in fetal TSH or T3. Control and treated neonates demonstrated similar physiological postnatal increases in TSH and T3, suggesting that prior exposure to TRH did not blunt this response. These data suggest that maternal administration of TRH is an effective way of increasing fetal T3 levels, and that this treatment does not inhibit the postnatal surge in TSH and T3.

Female↗
PubMed1984

Increase in density and accumulation of serotonin by human aging platelets.

51Cr-labeled autologous platelets were infused into splenectomized subjects and the specific radioactivities of high-density (HD) and low-density (LD) platelet subpopulations were determined sequentially in postinfusion samples. A rapid decrease in the specific radioactivity of LD cohorts (T1/2 = 2.5 days) was observed, but the specific radioactivity of HD platelets remained constant or increased slightly during the first 4 days and then gradually declined for the next 5 days. No experimental artifacts during the platelet-labeling steps that could account for these results were demonstrated. These findings confirm previous observations in eusplenic individuals and support the hypothesis that human LD platelets are, on the average, younger than HD platelets. LD platelets contain 33.8 +/- 13.5 ng serotonin (5HT)/10(8) platelets and HD platelets 76.8 +/- 9.5 ng 5HT/10(8) platelets (P less than 0.001). Sequential measurements of 5HT in PRP platelets were performed during the recovery phase of thrombocytopenia following splenectomy in patients with idiopathic thrombocytopenic purpura (ITP), a condition associated with aging of platelets in circulation. Presplenectomy platelet 5HT was 17.7 ng/10(8) platelets and on days 1, 6, and 12 after surgery it increased to 18.1, 37.8, and 61.0 ng/10(8) platelets (n = 7). When three healthy volunteers were given aspirin (500 mg/day) for up to 15 days, no significant change in the 5HT content of circulating platelets was observed. If aspirin blocks, at least partially, the secretory process in vivo without interfering the 5HT uptake by the platelets, this finding stands against the possibility that a net depletion of 5HT occurs during the life-span of normal human platelets. The observation that human HD platelets, enriched with older cells, contain more 5HT than LD platelets taken together with the parallel increase in platelet 5HT and age during the recovery from thrombocytopenia in ITP patients and the lack of effect of aspirin on platelet 5HT content, provides initial evidence that human platelets accumulate 5HT during their life-span in circulation.

Adolescent↗
PubMed1984

Kinetics of platelet density subpopulations in splenectomized mongrel dogs.

Autologous 51Cr-platelet kinetic studies were performed in splenectomized mongrel dogs. Mean survival time of PRP-platelets was 5.4 +/- 1.5 (SD) days (n = 6). The curves, though slightly curvilinear, showed mostly a linear type of decay, denoting that platelet removal from the circulation is mainly determined by aging of the cells. High-density (HD) and low-density (LD) platelet cohorts were isolated in Stractan gradients from samples drawn daily after infusion of labeled platelets. Specific radioactivity in HD cohorts declined rapidly postinfusion (T1/2 = 1.3 days), but specific radioactivity in LD platelets increased for 2 days and steadily declined for 4 days thereafter (n = 6). Labeled HD platelets, comprising 11.7% of the total population, lived significantly longer in circulation than LD platelets (19.1% of the total population) (n = 3). The patterns of decay of the radioactivity, however, do not have all the characteristics of pure age-cohort survival curves; 3.7 days after the infusion of labeled HD platelets, the specific radioactivity in LD cohorts was six times higher than on day 1, but attained only 20% of the initial specific radioactivity in HD platelets. After the infusion of labeled LD platelets no radioactivity was recovered in circulating HD cohorts. These findings indicate that mongrel dog platelets decrease in density with aging, but also that platelet density heterogeneity is in part determined during the thrombopoietic process. These data are consistent with those of other authors in rabbits and rhesus monkeys, but contrast with the observations that platelets in humans, baboons, and Macaca fascicularis monkeys increase in density with age, suggesting that the displacement of platelets toward compartments of either higher or lower density depends on the species under study.

Animals↗