Levels In Platelet-poor Plasma Research Articles

Local blood serotonin and soluble P-selectin levels during percutaneous transluminal balloon angioplasty and primary stenting of the iliac artery

The activation of platelets or leukocytes plays an important role in development of intimal hyperplasia. We investigated whether the local blood serotonin and soluble P-selectin levels changed during endovascular therapy of the iliac artery. Blood samples were obtained from the iliac artery of 18 lower limbs undergoing percutaneous balloon angioplasty alone (8 limbs, group I) or percutaneous balloon angioplasty and primary stenting (10 limbs, group II). The serotonin levels in platelet-poor plasma were measured in all limbs. In group I the urinary level of the serotonin metabolite 5-hydroxyindoleacetic acid was also measured 24 hours before and 24 hours after the procedures. The soluble P-selectin levels were measured in the 6 patients in group II. Before angioplasty the mean (+/- SEM) serotonin concentrations were 1.2 +/- 0.2, 1.2 +/- 0.4, and 1.2 +/- 0.3 ng/mL in all cases, group I, and group II, respectively. After angioplasty these values changed to 1.7 +/- 0.4 (P =.0750), 1.2 +/- 0.4 (P =.8001), and 2.1 +/- 0.6 ng/mL (P =.0529), respectively. In group I urinary 5-hydroxyindoleacetic acid concentrations 24 hours before and 24 hours after the procedures were 0.0026 +/- 0.0004 and 0.0031 +/- 0.0006 mg/mg creatinine, respectively (P =.2566). In group II the soluble P-selectin levels significantly increased after intervention, from 26.0 +/- 5.7 to 33.9 +/- 5.3 ng/mL (P =.0296). Although the serotonin levels did not change significantly, the soluble P-selectin levels increased significantly after intervention. Leukocyte activation may therefore contribute to the progression of restenosis after peripheral endovascular therapy.

Desialylated transferrin in plasma of patients with migraine without aura

Patients with migraine, without aura (MO), either during or between attacks, present elevated histamine levels in platelet-poor plasma but normal whole blood histamine levels, compared with controls. This finding is usually interpreted as an increased histamine release from basophils due to unidentified histamine-releasing factors. Compared with 10 control plasma samples, each sample from 12 MO patients (5 during and 7 between in attacks) contained normal amounts of iron and immunologically reactive transferrin but decreased transferrin iron-binding capacity. As transferrin inhibits histamine release in vitro, such as functional abnormality, probably due to modifications of the transferrin glycan moiety (desialylated transferrin), may well account for the increased histamine release observed in MO patients. We suggest that glycan-modified transferrin may be related to migraine histamine-releasing factors.

Effects of the menstrual cycle on dependent variables in mood disorder research.

The purpose of this article is to review the literature on the effects of the menstrual cycle on dependent variables in mood disorder research to inform investigators which physiological measures are likely to be significantly affected by menstrual cycle fluctuations and precisely how they might be affected. The following variables are discussed: prolactin; growth hormone; the hypothalamic-pituitary-thyroid axis (including thyrotropin, triiodothyronine, and thyroxine); the hypothalamic-pituitary-adrenal axis (cortisol, corticotropin, and beta-endorphin); melatonin; sleep; body temperature; and neurotransmitter activity (serotonergic and adrenergic systems). Body temperature and plasma and urinary norepinephrine vary predictably over the menstrual cycle. Prolactin and beta-endorphin may have peaks in the periovulatory phase, whereas serotonin levels in platelet-poor plasma may reach a nadir at that time. Triiodothyronine, thyroxine, cortisol, and melatonin do not appear to vary systematically over the course of the menstrual cycle, whereas the data for growth hormone, thyrotropin, corticotropin, and sleep are inconclusive.

Preeclampsia is not associated with altered platelet vasopressin binding and cytosolic Ca ++ concentration

Preeclampsia is an important cause of fetal and maternal morbidity and mortality. Recently it was described that platelet cytosolic Ca++ levels could be used to screen for preeclampsia. The current study investigated platelet arginine vasopressin receptor characteristics, platelet cytosolic Ca++ levels, plasma- and platelet-bound arginine vasopressin in white pregnant women. In a cross-sectional study nine third-trimester nulliparous pregnant women with gestational hypertension (seven with proteinuria, two with excessive weight gain without proteinuria) were compared with nine healthy nulliparous pregnant women matched for gestation length and age and 10 healthy age-matched nonpregnant women. Determined were (1) platelet arginine vasopressin receptor number and affinity, (2) platelet cytosolic Ca++ levels, both basal and on arginine vasopressin or thrombin stimulation, and (3) plasma- and platelet-bound arginine vasopressin levels. None of the measured parameters differed significantly among the three groups studied. Mean arginine vasopressin receptor number and affinity ranged from 108 to 143 receptors per platelet and 0.35 to 0.40 nmol/L, respectively. A single population of binding sites was found (Hill number 0.96). Basal Ca++ levels ranged from 113.4 to 133.3 nmol/L, on arginine vasopressin stimulation from 199 to 250 nmol/L. Median arginine vasopressin levels in platelet-poor plasma were between 1.2 and 2.4 pg/ml, with circulating platelets being estimated to possess two to five molecules of arginine vasopressin per platelet. A significant correlation was found between platelet cytosolic Ca++ levels before and after arginine vasopressin stimulation (r = 0.69, p < 0.001) and a weak correlation between platelet receptor density and arginine vasopressin-stimulated platelet cytosolic Ca++ levels (r = 0.38, p < 0.05). The studied parameters, platelet cytosolic Ca++ levels, whether basal or after stimulation with arginine vasopressin and vasopressin platelet receptor density and affinity, do not discriminate already hypertensive or preeclamptic white women from nondiseased subjects. A valuable test to screen for preeclampsia awaits further prospective studies.

A new competitive binding enzyme-linked immunosorbent assay for glycocalicin in plasma and platelet concentrate supernatants

A new competitive binding enzyme-linked immunosorbent assay (CB ELISA) for glycocalicin (GC) was developed using GC coated wells and a monoclonal antibody (MAb) to glycoprotein Ib (AN51). The principal stages of the CB ELISA consisted of coating the plate with GC extract overnight, blocking with 3% BSA, incubating the wells with test or standard sample dilution and AN51, and a final incubation with horseradish peroxidase-conjugated goat anti-mouse IgG. Serial dilutions of purified GC, starting in 2% BSA, yielded standard curves which were linear between 10 and 0.4 μg/ml. Parallel curves were obtained for platelet concentrate supernatants and for citrated plasma. We used the ELISA to measure GC levels in platelet concentrates during storage. The results indicated that soluble GC increased progressively during storage from 3.3 to 6.7 μg/ml, while GC levels in platelet-poor plasma remained at 1.9–2.2 μg/ml. These results show that the new CB ELISA is a simple and short assay for the direct measurement of GC in plasma solutions, and may be of use in clinical studies.

Serotonin Metabolism and Platelet Aggregation Under Antihypertensive Treatment with Nitrendipine

The effect of antihypertensive treatment with nitrendipine (10-40 mg/day) on serotonin metabolism and platelet aggregation was investigated in 13 hypertensive patients over a 6-month period. Normalization of elevated blood pressure was achieved [systolic blood pressure (SBP): 167 +/- 4 to 148 +/- 4 mm Hg, p less than 0.01; diastolic blood pressure (DBP): 108 +/- 2 to 95 +/- 3 mm Hg, p less than 0.01; chi +/- SEM before and after the treatment]. The decrease in plasma serotonin (5-HT) levels (354 +/- 140 to 179 +/- 49 nmol/L) and the platelet 5-HT content (9.6 +/- 3.5 to 2.8 +/- 0.9 nmol/10(9) Tro) was observed. Urinary 5-HT and 5-hydroxyindolacetic acid output did not show significant changes. Although the platelet aggregation decreased only moderately, a positive correlation was found between the 5-HT levels in platelet-poor plasma and platelet aggregation indices I (r = 0.699; p less than 0.001). The impaired 5-HT metabolism parameters (high platelet serotonin content and low 5-HT urinary output) in a washout period were normalized under the treatment with nitrendipine. It is concluded that the interaction with serotonergic metabolism could participate in antihypertensive mechanisms of nitrendipine. This effect is of clinical and theoretical importance when taking into account 5-HT atherogenic and mitogenic activity.

Epidermal growth factor in blood

The presence of receptors for epidermal growth factor (EGF) in a wide variety of human tissues and also some tumours indicates an as yet undefined role for EGF and it is therefore necessary to know precise concentrations in blood and other fluids. We have investigated the occurrence of EGF in the circulation and found that in platelet rich plasma, EGF levels were 51 ± 5 pmol/l (mean ± S.E.M., n = 6) while in platelet poor plasma levels were 2.9 ± 0.9 pmol/l . In contrast, serum EGF was 37 ± 7 pmol/l if separated at 30 min and rose to 117 ± 5 pmol/l if separated at 270 min. Gel chromatography showed that all residual EGF immunoreactivity in platelet poor plasma resided in the high molecular weight form thought to be non biologically active. In serum, delay in separation resulted in an increase in the proportion of EGF immunoreactivity co-eluting with EGF standard. These results suggest that EGF in the circulation is associated with platelets and that the process of blood coagulation leads to release of free EGF.

Increased levels of plasma 5-hydroxytryptamine in patients with coeliac disease.

In 17 patients with coeliac disease the 5-hydroxytryptamine (5-HT) concentration was measured in platelet-poor plasma (PPP) and in whole blood and compared with that of a control group of 30 healthy persons. The 5-HT level was determined by high-pressure liquid chromatography and electrochemical detection. In patients with coeliac disease the concentration of 5-HT in whole blood was elevated compared with the control group (p less than 0.001). The 5-HT level in PPP was significantly increased in patients with coeliac disease in whom the disease was untreated or treated with gluten-free diet for less than a year (p less than 0.01) but also compared with the patients with coeliac disease treated with a gluten-free diet for more than a year (p less than 0.01). In some untreated patients with newly diagnosed disease the 5-HT levels in PPP were markedly elevated and exceeded the levels ordinarily found in PPP in patients with carcinoid tumours. In these patients with coeliac disease the 5-HT concentration in PPP was reduced when the enteropathy was healed. There was no significant correlation between the 5-HT concentration in PPP versus whole blood in the different groups.

Fibrinogen in Liver Disease-Reply

In Reply.—Dr. Fine and I would seem to agree that research should be directed at the endotoxin detoxifying capacity of the Kupffer cells of the liver. I am sure that my own results were performed on platelet-poor plasma, except where a platelet assay was being deliberately used, as in Fig 4 of my article. We also have looked into the report by Das et al and have found that it is the chloroform extraction technique that often gives a positive assay with platelet-rich plasma, whereas this is not so when the extraction of euglobulins and endotoxin inhibitors is performed by the acidification technique of Reinhold and Fine. We have therefore abandoned chloroform but still get similar assay levels in platelet-poor plasma.