Environmental stress on diving-induced platelet activation.

Platelet activation has been suggested to play an important role in the pathogenesis of prethrombotic states and thus may be responsible for decompression illness during compressed air (scuba) diving. To investigate the effect of physical, mental, and environmental stress on platelet activation during immersion in ice-cold water, we examined 10 male breath-hold divers (BHD), 10 elite BHD (eBHD), and 10 scuba divers during immersion in an ice-covered lake at moderate altitude. Platelet activation was examined by surface expression of activation-dependent glycoproteins CD62p, CD63, and CD42a with flow cytometry 10 min before and 1 min and again 24 h after diving. Plasma epinephrine level was also measured. In addition, the relationship between the activated platelets and the epinephrine level was evaluated. The percentage of platelet activation increased from 2.1 +/- 0.4 to 5.7 +/- 0.3, 1.8 +/- 0.3 to 12.9 +/- 0.8, and 3.7 +/- 0.9 to 31.2 +/- 0.8 in BHD, eBHD, and scuba divers, respectively. The percentage of platelet activation returned to pre-immersion levels in BHD and eBHD divers 24 h after diving, but was still higher in scuba divers. A positive relationship exists between the plasma epinephrine level and the percentage of the platelet activation. This study suggests that physical and mental stress enhance platelet activation during diving in ice-cold water.

Fluvastatin reduces soluble P-selectin and ICAM-1 levels in hypercholesterolemic patients: role of nitric oxide.

BACKGROUND: Lipid-lowering therapy with 3-hydroxy-3-methylglutaryl-coenzymeA (HMG-CoA) reductase inhibitors reduces the incidence of atherosclerosis-related cardiovascular events. Adhesion molecules, regulating interactions between vascular and circulating cells, may play a central role in the pathogenesis of atherosclerosis and related complications. In the present report we examined the impact of the HMG-CoA reductase inhibitor fluvastatin on plasma levels of P-selectin and ICAM-1. METHODS: Plasma levels of P-selectin and ICAM-1 were determined using an enzyme immunoassay in 26 patients with type IIa hypercholesterolemia randomized to treatment with either fluvastatin (80 mg/d) or placebo in a double blind fashion for 12 weeks. RESULTS: Fluvastatin administration reduced either P-selectin (118 +/- 63 vs 81 +/- 36 ng/mL [-31%], P = 0.0015) or ICAM-1 (264 +/- 75 vs 228 +/- 68 ng/mL [-13.7%], P = 0.0033) levels. Fluvastatin also lowered urinary 11-dehydro-TXB2 (1396 +/- 536 vs 1009 +/- 378 pg/mg creatinine [-27%], P = 0.0015) and von Willebrand Factor levels (1456 +/- 716 vs 1203 +/- 527 U/L [-17.4%], P = 0.0275), and a direct correlation was observed between P-selectin and 11-dehydro-TXB2 levels (r = 0.588, P = 0.0033). Patients treated with fluvastatin displayed an increase in nitric oxide (NO) generation, evaluated with measurements of serum NO2-/NO3-, (4.7 +/- 1 vs 8.9 +/- 3.1) mumol/L [98%], P = 0.0046). Moreover, an inverse correlation was observed between NO2-/NO3- and P-selectin (r = -0.420; P = 0.0343), 11-dehydro-TXB2 (r = -0.511; P = 0.0106), or LDL (r = -0.742; P = 0.0002) levels. CONCLUSIONS: These results may provide novel biochemical basis for the beneficial clinical effects of HMG-CoA reductase inhibitors in hypercholesterolemia.

Effect of thyroid function on LDL oxidation.

In this study, the effect of different levels of thyroid hormone and metabolic activity on low density lipoprotein (LDL) oxidation was investigated. Thus, in 16 patients with hyperthyroidism, 16 with hypothyroidism, and 16 age- and sex-matched healthy normolipidemic control subjects, the native LDL content in lipid peroxides, vitamin E, beta-carotene, and lycopene, as well as the susceptibility of these particles to undergo lipid peroxidation, was assessed. Hyperthyroidism was associated with significantly higher lipid peroxidation, as characterized by a higher native LDL content in lipid peroxides, a lower lag phase, and a higher oxidation rate than in the other two groups. This elevated lipid peroxidation was associated with a lower LDL antioxidant concentration. Interestingly, hypothyroid patients showed an intermediate behavior. In fact, in hypothyroidism, LDL oxidation was significantly lower than in hyperthyroidism but higher than in the control group. Hypothyroidism was also characterized by the highest beta-carotene LDL content, whereas vitamin E was significantly lower than in control subjects. In hyperthyroidism but not in the other two groups, LDL oxidation was strongly influenced by free thyroxine blood content. In fact in this group, the native LDL lipid peroxide content and the lag phase were directly and indirectly, respectively, related to free thyroxine blood levels. On the contrary, in hypothyroidism LDL oxidation was strongly and significantly related to serum lipids. In conclusion, both hypothyroidism and hyperthyroidism are characterized by higher levels of LDL oxidation when compared with normolipidemic control subjects. In hyperthyroid patients, the increased lipid peroxidation was strictly related to free thyroxine levels, whereas in hypothyroidism it was strongly influenced by serum lipids.

[Collagen-induced platelet aggregation in K562 neoplastic cells culture media]. / L'aggregazione piastrinica indotta da collagene in presenza di terreno di coltura di cellule neoplastiche K562.

The evidence suggests that the propagation of neoplastic cells by solid tumors, seem the platelets have a protective role on the neoplastic cells respect to immunocompetent system. In this study, the AA. valued the variation of platelet aggregation induced by collagen when PRP was incubated with liquid culture of neoplastic cells K562. The preliminary results, show the platelet aggregation induced by collagen, increase alter interaction with this liquid culture.

Platelet subpopulations in adult and geriatric males.

In this study, the authors wanted to investigate the volume, density, and percentage of three platelet subpopulations present in adult and geriatric males. Ninety subjects, between the ages of 20 and 40, were chosen for the adult group and 50 subjects, all older than age 70, were used for the geriatric group. The platelet subpopulations were separated with discontinuous gradients of Percoll. The results obtained from the three platelet subpopulations--low, intermediate, and high density--show different volumes and percentages in both the groups studied. From the information that larger platelets can be expected to have a longer life span, it was possible to hypothesize that platelets found in geriatric males have a reduced average life span. It is also clear that platelets exist that have similar volumes but different densities.

[Total lactate dehydrogenase content and its isoenzymes in a human platelet subpopulation]. / Contenuto in latticodeidrogenasi (LDH) totale e suoi isoenzimi nelle sottopopolazioni piastriniche umane.

The morphological and functional variability of the platelets is on the way of the study. The morphological platelet transformations corresponding to functional attitudes, need of energetic pattern given by the content, in platelets, of enzymatic patrimony. The results show that the lactic-dehydrogenase and isoenzymes, content in the three studied platelet subpopulations, is different. These significant data, probably show that the platelet subpopulations have a different content in total LDH while show no modification in LDH isoenzymes as show in various functional and energetic different specific point in time.

[Platelet aggregation induced by adenosine diphosphate, collagen and adrenaline in human platelet subpopulations]. / Aggregazione piastrinica indotta da adenosin difosfato, collagene ed adrenalina nelle sottopopolazioni piastriniche umane.

The study of platelet aggregation is normally carried out with the use of "Platelet Rich Plasma" (PRP) in which is grouped the overall platelets population. We have divided this population in three defined subclasses by gradients with discontinuous density, so as to test their own functional response towards three aggregant agents: adenosine diphosphate, epinephrine and collagen. The obtained results have been compared by an Aggregation Index, calculated as a ratio between the maximum percentage of aggregation and platelets mass. In this way it is pointed out a discriminating behaviour in three groups of thrombocytes relative to a functional different attitude towards different inducers and associated to an activation of heterogeneous way.

[Effects of dihydrostreptomycin and gentamycin on platelet membrane Na+-K+ATPase]. / Azione della diidrostreptomicina e della gentamicina sulla Na+-K+ATPasi di membrana piastrinica.

The use of aminoglycosides is characterised by a bound linkage between therapeutic and toxical levels. The aim of our study was to define the influence of diidrostreptomicin and gentamicin over Na+-K+ATPase of membranes of platelets. In this study, Bounting's and Caravaggio's method has been used, while ATPase activity was expressed in n mol of hydrolized ATP/min/mg of proteins. The data so obtained showed that the antibiotics were able to block up ATPase activity.

[Effects of aminoglycosides on T and B lymphocyte populations: in vitro study]. / Effetti degli aminoglicosidi sulle popolazioni linfocitarie T e B: studio "in vitro".

The authors tested the influence of gentamycin, spectinomycin,and dihydrostreptomycin on the formation of EAChu and EAT rosettes and they have found a significant reduction of the percentage of EAChu rosettes. Probably this reduction is due to an interaction with the receptor sites for the Complement of B lymphocytes and/or an in vitro denaturation Complement.

[Action of aminoglycosides on platelet aggregation in vitro]. / L'azione degli aminoglicosidi sulla aggregazione piastrinica in vitro.

The authors tested the influence of gentamicin, spectinomycin dihydrostreptomycin on the ADP and epinephrine in vitro induced platelet aggregation. Our aim was to demonstrate if platelet aggregation in vitro had some influences by antibiotics. A reduction in platelet aggregability, strictly dependent from the used antibiotic dose was observed. We have studied platelet function thanks to Born's method, adding to PRP gradual therapeutics doses of antibiotics. The results showed a reduction of platelet function which was dose-depended, and, particularly, gentamicin seemed to be the most effective among aminoglycosides. An interference between these drugs and the ADP and epinephrine binding to specific platelet receptor sites is proposed.

[Evaluation of pressure and mechanical effects on the aggregation of human platelets induced by adenosine diphosphate in a system simulating a dialysis circuit]. / Valutazione delle azioni pressorie e meccaniche sull'aggregazione delle piastrine umane indotta con adenosina difosfato (ADP) in un sistema simulante il circuito di dialisi.

Blood samples in sodium citrate 3.8% (ratio 1:10) of 15 healthy people were subjected to the pressure of 0, 50, 150 mm Hg respectively in a circuit operated by a peristaltic pump as during dialysis. The platelet aggregation induced by adenosine diphosphate (ADP) was determined in all cases. We found a significant reduction of the maximum percent aggregation of the samples exposed to the pressure of 150 mm Hg. We then suppose that a positive correlation exists between high pressure in the dialytic circuit and platelet damage.

[Isoenzyme fractions of serum and platelet lactate dehydrogenase in normal subjects]. / Studio delle frazioni isoenzimatiche del lattato deidrogenasi sierico ed endopiastrinico in soggetti normali.

We determined the isoenzymatic fractions of platelets and seric LDH in off healthy people (50 males and 50 females). We broken the platelets by triton X 100 (octylphenoxypolyethoxyethanol) in order to obtain the release of platelet LDH. The seric and platelet LDH isoenzymes were then separated by electrophoresis (Gelman sistem). We confirm the prevalence of LDH2 and LDH3 fractions in human platelets.

[The influence exercised by various temperatures on platelet aggregation in vitro]. / Studio sull'influenza esercitata dalle diverse temperature sull'aggregabilità piastrinica "in vitro".

To obtain a regular haemostasis is necessary that the platelets are numerically sufficient and functionally normal. Many factors influence on platelet aggregation; among these platelet shape, dimensions and volume. In our study we have analysed the temperature influence on platelet aggregation. In a group of 27 subjects we have demonstrated that the platelet rich plasma pre-incubation for 30 minutes in ice-bath does not modify the platelet aggregation capacity. On the contrary, the platelet rich plasma pre-incubation for 30 minutes at 37 degrees C reduces considerably the platelet aggregation, probably for the platelet volume reduction.

[Relation between vitamin A and the fragility of red blood cells subjected to continuous mechanical trauma]. / Correlazioni tra vitamina A e fragilita' dei globuli rossi sottoposti a trauma meccanico continuo.

Is well-known the haemolitic action that A-vitamine exerts on the erythrocytes. With our study we have submitted the erythrocytes, of forty normal subjects, to incubation to 37 degrees C and to constant traumatic action with and without A-vitamine. After we have dosed the haemoglobin and potassium in the plasma to various times of incubation and traumatic action. The results demonstrate that this vitamine determines an increase of the fragility of the erythrocytes beyond the 100% after 120 minutes, while protects the membrane of erythrocytes to the release of potassium.

[Adherent capacity of human macrophages in short-term cultures. Activity in an aged population]. / Studio della capacita' aderente dei macrofagi umani in colture a breve termine. Attivita' nella popolazione anziana.

We studied the morphological modifications that the adherent human cells of aged subjects show in short term cultures in an atmosphere containing 5% CO2, in comparison with young controls. The sequential variations in the morphological aspect are nearly the same of the young subject, but they seem to occur late, during the observations at 2,4,8,20 hours.