Muscle injury induces an increase in total and non-rapid eye movement sleep time.

STUDY OBJECTIVES: This study describes macro- and micro-sleep responses to a myotoxic skeletal muscle injury and investigates possible mechanisms. METHODS: We recorded the electroencephalogram (EEG)/electromyogram (EMG) of 24 Wistar rats before and after induction of tibialis anterior muscle injury (n = 8 per group: control, control + buprenorphine and injured). A top-down analysis of sleep characteristics was processed from total sleep time (TST), sleep stages, sleep stability, spectral analysis, and spindles. To further investigate the mechanisms involved, we analyzed the protein level of sleep regulatory molecules including tumor necrosis factor- α (TNF-α), interleukin-1ß (IL-1ß), insulin-like growth factor-1 (IGF-1), and brain and muscle ARNT-like 1 (BMAL1) in plasma, frontal cortex, hippocampus, and tibialis anterior, collected at day +2 after injury from non-EEG/EMG implanted rats. RESULTS: Muscle injury induces a significant increase in TST at 48 and 72 h post-injury, specific to non-rapid eye movement (NREM) sleep. These increases occur during the dark period and are associated with the higher stability of sleep over 24 h, without change in the different power/frequency spectral bands of NREM/REM sleep. There was no corresponding sleep increase in slow-wave activity or spindle density, nor were there changes in brain levels of the sleep-regulating proinflammatory cytokine IL-1ß, which is otherwise involved in the local response to injury. Conversely, decreased protein levels of brain IGF-1 and muscle BMAL1, a core circadian clock gene, after injury may play a role in increased sleep time. CONCLUSION: Muscle injury induces an increase in total sleep time at 48- and 72-h post-injury, specific to NREM sleep during the dark period in rats and is associated with higher sleep stability over 24 h.

The utility of computed tomography and diffusion-weighted magnetic resonance imaging fusion in cholesteatoma: illustration with a UK case series.

OBJECTIVE: Post-processing imaging techniques allow high-resolution computed tomography and diffusion-weighted magnetic resonance imaging of the temporal bone to be superimposed and viewed simultaneously (fusion imaging). This study aimed to highlight the practical utility of fusion imaging for disease localisation and evaluation in a UK case series of primary and post-operative cholesteatoma. METHOD: Fusion of computed tomography and diffusion-weighted magnetic resonance b1000 images was performed using specific software. Axial computed tomography images and coronal b1000 images were selected for fusion. RESULTS: A case series of primary and post-operative cholesteatoma in which computed tomography and magnetic resonance imaging fusion assisted the management of both the patient pathway and surgical approach is reviewed. CONCLUSION: Computed tomography and magnetic resonance imaging fusion can assist in pre-operative surgical planning and patient counselling through assessment of disease in both primary and revision scenarios. Computed tomography and magnetic resonance imaging fusion can assist the operative surgeon through accurate localisation that can influence both the operative technique and optimise operation theatre utilisation.

Epigenetic therapy restores normal hematopoiesis in a zebrafish model of NUP98-HOXA9-induced myeloid disease.

Acute myeloid leukemia (AML) occurs when multiple genetic aberrations alter white blood cell development, leading to hyperproliferation and arrest of cell differentiation. Pertinent animal models link in vitro studies with the use of new agents in clinical trials. We generated a transgenic zebrafish expressing human NUP98-HOXA9 (NHA9), a fusion oncogene found in high-risk AML. Embryos developed a preleukemic state with anemia and myeloid cell expansion, and adult fish developed a myeloproliferative neoplasm (MPN). We leveraged this model to show that NHA9 increases the number of hematopoietic stem cells, and that oncogenic function of NHA9 depends on downstream activation of meis1, the PTGS/COX pathway and genome hypermethylation through the DNA methyltransferase, dnmt1. We restored normal hematopoiesis in NHA9 embryos with knockdown of meis1 or dnmt1, as well as pharmacologic treatment with DNA (cytosine-5)-methyltransferase (DNMT) inhibitors or cyclo-oxygenase (COX) inhibitors. DNMT inhibitors reduced genome methylation to near normal levels. Strikingly, we discovered synergy when we combined sub-monotherapeutic doses of a histone deacetylase inhibitor plus either a DNMT inhibitor or COX inhibitor to block the effects of NHA9 on zebrafish blood development. Our work proposes novel drug targets in NHA9-induced myeloid disease, and suggests rational therapies by combining minimal doses of known bioactive compounds.

[Insomnia and total sleep time in France: prevalence and associated socio-demographic factors in a general population survey]. / Prévalence et facteurs sociodémographiques associés à l'insomnie et au temps de sommeil en France (15-85ans).

INTRODUCTION: Sleep is considered as a major protective factor for good health and quality of life. The epidemiology of chronic insomnia and other sleep disorders has recently been developed in France. The aim of this study was to evaluate total sleep time and the prevalence of chronic insomnia in the general population aged 15 to 85 years. It was also to investigate factors associated with sleep disorders. METHODS: Within the framework of the Health Barometer 2010, a French general population survey, 27,653 15 to 85-year-old individuals were questioned about their health behaviors and attitudes, in particular about their sleeping time and habits. RESULTS: The average sleeping time of the 15 to 85-year-old was 7 hours 13 minutes. It was higher for women than for men (7 hours 18 minutes vs 7 hours 07 minutes; P<0.001), whereas 15.8 % of the population presented criteria for chronic insomnia, 19.3 % of women and 11.9 % of men (P<0.001). The prevalence of chronic insomnia was stable with age among women, around 19 %, whereas it increased for men from 3 % in the 15-19-year age range to 18 % in the 45-54-year age range, before decreasing to 8 % beyond 65 years. Chronic insomnia was also found to be related to precarious situations and to several difficult events of life such as violence or chronic alcohol abuse, whereas the relationship observed with tobacco smoking was no longer found after logistic regression adjustment for socio-demographic characteristics. Since the beginning of 1990s, a single-question inquiry on "sleeping problems present during the last 8 days" has been asked in the Health Barometer. The rate of subjects concerned increased from 1995, with a prevalence stabilized at a high level since 2000. CONCLUSIONS: Based on these data, we think that the surveillance of sleep disorders is an important public health issue and that prevention and health educational initiatives should be launched in the general population to promote a better quality of sleep.

Diosgenin induces death receptor-5 through activation of p38 pathway and promotes TRAIL-induced apoptosis in colon cancer cells.

Previously, we demonstrated that diosgenin induced apoptosis in colorectal cancer cell lines HCT-116 and HT-29. HT-29 cells have been reported to be one of the most resistant colorectal cancer cell lines to TRAIL-induced apoptosis. In this study, we investigated the effect of diosgenin on TRAIL-induced apoptosis in HT-29 cells. We showed that diosgenin sensitizes HT-29 cells to TRAIL-induced apoptosis. Mechanisms underlying this sensitization mainly involved diosgenin-induced p38 MAPK pathway activation and subsequent DR5 overexpression. Furthermore, we showed that diosgenin alone, TRAIL alone or combination treatment increased COX-2 expression and that the use of a COX-2 inhibitor further increased apoptosis induction.

Roots of Daphne gnidium L. inhibit cell proliferation and induce apoptosis in the human breast cancer cell line MCF-7.

Daphne gnidium L. is a well-known Moroccan plant with cancer-related ethnobotanical use. In order to systematically evaluate its potential activity in breast cancer, four extracts from this plant of different polarity were tested for their antiproliferative effects on MCF-7 cells. The second aspect of this study related to understanding the nature and mechanism of the antiproliferative effect. Results from a viability assay showed the potent antiproliferative capacity of the hexane (IC(50)-48 h: 630 +/- 16 microg/ml), dichloromethane (IC(50)-48 h: 112 +/- 7 microg/ml) and ethyl acetate extracts (IC(50)-48 h: 263 +/- 9 microg/ml). On the other hand the methanol extract was inactive. LDH test revealed the cytotoxicity of the hexane extract as opposed to two others. The characterization of the ethyl acetate extract showed its dose-dependent pro-apoptotic effect. Surprisingly, we observed that activation of the inducible cyclooxygenase-2 followed the kinetics of apoptosis development. On the other hand, the dichloromethane extract showed a distinct effect on COX-2 activity as a function of the used dose. A low dose seemed to inhibit COX-2 activity whereas a high dose seemed to increase it. These findings suggest that Daphne gnidium L. might be of potential chemopreventive interest. Other studies are in hand to isolate the active agents responsible for the antiproliferative effect.

[Impact of nocturia on sleep efficiency in patients with benign prostatic hypertrophy]. / Etude observationnelle nationale (Association française d'urologie) de l'impact de la nycturie sur le sommeil des patients porteurs d'une hyperplasie bénigne de la prostate.

OBJECTIVE: To assess sleep efficiency in patients presenting with nocturia and symptomatic benign prostatic hypertrophy (BPH). MATERIAL AND METHODS: This prospective observational survey was carried out in France by 113 urologists. A total of 1376 patients (mean+/-SD age: 68.8+/-9.0 years) consulting for BPH with greater than two nocturia episodes per 24 hours were assessed with a mean I-PSS score of 15.5+/-6.4 (symptoms greater than 19 [severe] in 26.9% of cases). Patients used a sleep diary to record the previous night's total; sleep efficiency is expressed as percentage ratio, representing the total amount of actual sleep between initial sleep onset and final awakening. Sleep disorders were assessed using HD-43 questionnaire based on International classification of sleep disorders. RESULTS: 29.2% of the patients suffered from chronic insomnia, considered as primary insomnia (in 29.5% of cases) or related to either BPH (63.0%); snoring/sleep apnoea in 12.5% of cases. The mean sleep efficiency index was 87.2+/-13.7% and appeared to be significantly lower in BPH-related insomnia. Significantly lower sleep efficiency index values were observed as the severity (I-PSS score) of the BPH symptoms increased (89.5+/-12.1% for mildly symptomatic BPH vs. 84.0+/-15.6% for severely symptomatic BPH, P<0.001). Sleep efficiency index lowered with nocturia frequency (89.8+/-11.3% for two nocturia episodes vs. 80.4+/-17.3% for five nocturia episodes or more, P<0.001) and chronic insomnia frequency increased with nocturia frequency (21.4% for two nocturia episodes vs. 45.2% for five nocturia episodes or more, P<0.001). CONCLUSIONS: Insomnia is frequent in patients presenting with BPH-related lower urinary tract symptoms (LUTS) and is mainly secondary to these LUTS. There is a significant correlation between the frequency of nocturia and the severity of insomnia.

Sedimentation field flow fractionation to study human erythroleukemia cell megakaryocytic differentiation after short period diosgenin induction.

Anti-cancer differentiation therapy could be one strategy to stop cancer cell proliferation. We propose a new sedimentation field flow fractionation (SdFFF) cell separation application in the field of cancer research. It concerns the study of megakaryocytic differentiation processes after a short exposure to an inducting agent (diosgenin). Washout process and early dual SdFFF separation--removing the influence of diosgenin and decreasing the influence of undifferentiated cells--resulted in the preparation of an enriched population to study the mechanism and kinetics of megakaryocytic differentiation. A short exposure to diosgenin was able to induce complete differentiation leading to maximal maturation which ended naturally after 192h incubation without the influence of a secondary effect of diosgenin. The study of isolated undifferentiated cells also showed that no resistance to diosgenin was observed. This result suggested different sensitivities to differentiation induction, and SdFFF cell separation would be of great interest to explore this phenomena.

Low dose leflunomide activates PI3K/Akt signalling in erythroleukemia cells and reduces apoptosis induced by anticancer agents.

Rheumatoid arthritis (RA) is characterized by persistent joint synovial tissue inflammation. Leflunomide is an immunomodulatory agent that has been approved for treatment of active RA. In the past few years, uses other than RA treatment have appeared. Leflunomide has been reported to show antitumor potential through inhibition of cancer cell proliferation. We thus tested the antiproliferative potential of leflunomide on HEL and K562 erythroleukemia cells. The findings summarized in this report demonstrate for the first time that low dose leflunomide prolonged survival and reduced apoptosis induced by several anticancer agents in erythroleukemia cells. We showed that in treated cells, leflunomide reduced the signalling pathways involved in promoting apoptosis by reducing p38 MAPK and JNK basal activity. On the other hand, leflunomide transiently activated the ERK signalling pathway and induced a sustained activation of Akt. We also showed that leflunomide reduced caspase-3 activity and DNA fragmentation induced by anticancer agents. By using an inhibitory strategy, we showed that inhibition of Akt activation but not ERK abolished the protective effect of leflunomide. Thus our findings suggested that leflunomide reduced apoptosis induced by anticancer agents through PI3K/Akt signalling activation.

Pre-apoptotic sub-population cell sorting from diosgenin apoptosis induced 1547 cells by Sedimentation Field-Flow Fractionation. The effect of channel thickness on sorting performance.

Apoptosis is one of the most important phenomena in cell biology. Pre-apoptotic cells, defined as cells engaged in early stages of apoptosis, could be used as a cellular tool to study apoptosis pathways. The human 1547 osteosarcoma cell line and diosgenin (a plant steroid) association was selected as an in vitro cellular apoptosis model. In a previous study, using this model, we demonstrated that SdFFF monitored apoptosis induction as early as 6h after incubation. In this study, we investigated the capacity of Sedimentation Field-Flow Fractionation (SdFFF) to sort an enriched population of pre-apoptotic cells from 1547 cells incubated for 6 h with 40 microM diosgenin. In that way, two different separation devices which differed especially in channel thickness, 125 and 175 microm, were used and compared. Results showed, for the first time, that SdFFF is an effective method to obtain an enriched pre-apoptotic sub-population. These results suggest, as a new application, that SdFFF could be an included tool in the study of apoptotic mechanisms or the kinetic action of apoptotic drugs.

Megakaryocyte cell sorting from diosgenin-differentiated human erythroleukemia cells by sedimentation field-flow fractionation.

Anticancer differentiation therapy could be one strategy to stop cancer cell proliferation. Human erythroleukemia (HEL) cell line, incubated with 10 microM diosgenin, underwent megakaryocytic differentiation. Thus, the association diosgenin/HEL could be used as a model of chemically induced cellular differentiation and anticancer treatment. The goal of this work was to determine the capacity of sedimentation field-flow fractionation (SdFFF) to sort megakaryocytic differentiated cells. SdFFF cell sorting was associated with cellular characterization methods to calibrate specific elution profiles. As demonstrated by cell size measurement methods, cellular morphology, ploidy, and phenotype, we obtained an enriched, sterile, viable, and functional fraction of megakaryocytic cells. Thus, SdFFF is proposed as a routine method to prepare differentiated cells that will be further used to better understand the megakaryocytic differentiation process.

Cardiorespiratory consequences of sleep apnoea syndrome in patients with massive obesity.

Assessment of cardiorespiratory consequences of sleep apnoea syndrome (SAS) is difficult owing to confounding factors, especially obesity, that are strongly associated with SAS. This study was designed to assess the cardiorespiratory consequences of SAS by comparing the results of a comprehensive cardiorespiratory evaluation in apnoeic and nonapnoeic patients with massive obesity. In a retrospective chart-review study, we studied 60 patients with massive obesity defined by a body mass index (BMI) >40 kg.m(-2), presenting no chronic respiratory disease, who underwent an extensive assessment of cardiorespiratory consequences of obesity, including overnight polysomnography, lung function tests, arterial blood gas analysis, evaluation of vascular risk factors, myocardial scintigraphy with dipyridamole stress-test, isotopic ventriculography, Doppler echocardiography and Holter electrocardiogram recording. SAS defined by an apnoea + hypopnoea index (AHI) > or = 10 was diagnosed in 42% of patients (25 out of 60). Mean+/-SD AHI of SAS-positive (SAS+) patients was 38+/-24. Age, BMI, ventilatory function parameters, prevalence of smoking history and diabetes mellitus did not differ significantly in SAS+ versus SAS-negative (SAS-) groups. The following complications were observed more frequently in SAS+ than in SAS- patients: daytime hypoxaemia (35 vs 9%, p<0.02), pulmonary arterial hypertension (36 vs 7%, p<0.05) and increased interventricular septal thickness (50 vs 15%, p<0.03). No association was found between SAS on the one hand and systemic arterial hypertension, coronary artery disease, left ventricular dysfunction and nocturnal cardiac arrhythmias on the other. Nocturnal apnoeas in massive obesity may thus be associated with moderate daytime hypoxaemia, mild pulmonary arterial hypertension and moderate left ventricular hypertrophy, but not with severe cardiorespiratory complications.

[Hysterectomy. Indications, abuse, psychological impact]. / Réflexions á propos de l'hystérectomie. Indications, abus, retentissement psychologique.

Statistical surveys have established that, in France, hysterectomy was carried out too frequently: 50 to 70,000 hysterectomies (perhaps only 40,000) are carried out each year in our country. This fact, together with the deleterious psychological effects of this operation, have urged the authors to express some remarks on the current practice of hysterectomy in France. The currently approved indications are the following: invasive cancer, benign lesions with intractable disabling symptoms and technical requirements (e.g. cure of prolapse in the elderly). Bleeding due to fibromyomas should be managed with conservative means as much as possible. Infections are within the scope of medical treatment. When an hysterectomy is indicated, the vaginal route should be preferred whenever possible, due the lesser impact on the body image and personality. The adverse psychological effects of hysterectomy are due to several factors: fear of the operation, pain, possible complications, breach of the femininity, alteration of the body image, fear of menopause and ageing. These effects could be reduced by an accurate information of the patient on the actual consequences of the operation, which are far from considerable, specially if the hormonal secretion is preserved. Also, a certain period of time between the decision and the operation might help to further reduce this psychological impact.

Home nasal continuous positive airway pressure in infants with sleep-disordered breathing.

OBJECTIVE: To review our experience with home nasal continuous positive airway pressure (CPAP) in infants with small upper airways and abnormal breathing during sleep. STUDY DESIGN: Seventy-four infants with sleep-disordered breathing and narrow upper airways, as identified by nocturnal polygraphic recording and endoscopic evaluation, were treated at home with nasal CPAP. Infants with craniofacial anomalies and trisomy 21, and infants who had been referred to us as having had "apparent life-threatening events," made up the majority of the population. Because of the rapid growth of infants, regular follow-up visits were scheduled to adjust CPAP and mask size. RESULTS: Seventy-two infants were successfully treated at home with nasal CPAP; there were two failures. Follow-up lasted from 5 months to 12 years. Compliance was not a problem, but home nasal CPAP was prescribed only for infants who lived close to our center and whose families and pediatricians were willing to support compliance. COMMENTS: Home nasal CPAP requires careful, in-laboratory titration and regular follow-up to adjust both pressure and mask size. With the support of families and pediatricians, home nasal CPAP can be an effective treatment for infants with upper airway respiratory problems during sleep. In many cases, it can provide an interim solution, enabling physicians to plan surgery at an appropriate time and giving infants time to grow before having to undergo surgical stress.

Change in glycosylation of chicken transferrin glycans biosynthesized during embryogenesis and primary culture of embryo hepatocytes.

Transferrins were isolated by immunoaffinity chromatography from chicken serum, chicken embryo serum and from the culture medium of chicken embryo hepatocytes in primary culture. The glycovariants of these three transferrins were separated by ion-exchange chromatography using a fast protein liquid chromatography (FPLC) system. The structures of the oligosaccharide-alditols released by hydrazinolysis from the glycovariants were compared after analysis by a combination of methanolysis, methylation analysis and 1H-NMR spectroscopy. In the three transferrins analysed, the oligosaccharides were of the biantennary N-acetyllactosaminic type, having several prominent features. In particular, the embryo serum transferrin glycan differed from that of chicken serum transferrin by the presence of a bisecting N-acetylglucosamine, suggesting a developmental change in glycosylation. The glycan structure of the transferrin secreted by the embryo hepatocytes in primary culture was marked by the presence of fucose (alpha 1-6) linked to the core N-acetylglucosamine, suggesting that expression of the fucosyltransferase activity is dependent on cell culture conditions. Moreover, comparative analysis of chicken serum transferrin and ovotransferrin glycans reinforces the idea that the glycosylation of two identical polypeptide chains is organ specific.

[Campaign against allergenic moulds in dwellings. Inhibitor properties of essential oil of Geranium 'Bourbon', citronellol, geraniol and citral]. / Lutte contre les moisissures allergisantes des habitations. Propriétés inhibitrices de l'huile essentielle de Géranium 'Bourbon', du citronellol, du géraniol et du citral.

Many fungal airborne spora show allergenic effects. Indoor (dwelling, work rooms, hospital chambers) can be disinfected by elimination of living particles. We have undertaken experiments in more and more spacious bulks for evaluation of the antifungal effects of vapours of essential oils and some volatiles compounds. Results show that the Mucorales and Geotrichum resist strongly. On the contrary, the Cladosporium strains, some Aspergillus and Penicillium, Trichothecium roseum are the most sensitive, specially towards the citral vapours. Experiments in hospital can be undertaken.

Reversal effects of topical retinoic acid on the skin of kidney transplant recipients under systemic corticotherapy.

The systemic long-term corticosteroid treatment administered to kidney graft recipients (KGR) within the framework of the required immunosuppressive therapy induces an atrophy of the skin, from the sixth month onwards. We studied the effect of topical all-trans retinoic acid (0.05%; Galderma Labs.) applied to the forearms of 27 KGR (14 men, 13 women) over a 6-month period. Twenty-four subjects completed the trial. The following results were obtained in the treated forearm versus the untreated forearm (excipient alone): clinically, an increase in skin thickness; by noninvasive techniques, an increase in skin thickness, skin elasticity, skin conductance, and TEWL, and a reduction in the size of the corneocytes. No change in stratum corneum lipid content was observed. A sex-related difference was noted in the response to treatment under our experimental conditions, the female patients responding better. A punch biopsy (4 mm) was performed on both forearms of four patients after the 6-month period. Histologic and ultrastructural examination revealed epidermal and dermal changes evoking increased cellular metabolism in the retinoic acid-treated forearms.

Presence of fucosylated triantennary, tetraantennary and pentaantennary glycans in transferrin synthesized by the human hepatocarcinoma cell line Hep G2.

Transferrin synthesized by a human hepatocellular carcinoma cell line Hep G2 (called Hep G2 transferrin) was purified from culture media by immunoaffinity chromatography on a rabbit anti-(human serotransferrin) IgG column. The eluted transferrin was then resolved into five peaks on a cation-exchange column using the fast protein liquid chromatography system. The major fraction, named Hep G2 transferrin fraction C, having a molecular mass of 82.5 kDa was found to be homogeneous in polyacrylamide gel electrophoresis and in concanavalin-A-affinity crossed immunoelectrophoresis. A comparative analysis of the molar carbohydrate composition of normal human serotransferrin and of Hep G2 transferrin fraction C shows an increase in the latter in the number of galactose and N-acetylglucosamine residues and in the presence of fucose, which is absent in normal transferrin. By a combination of methylation analysis and NMR spectroscopy, the primary structure of the oligosaccharide alditols released from Hep G2 transferrin fraction C by reductive alkaline cleavage has been established as triantennary, tetraantennary and pentaantennary N-acetyllactosaminic structures with fucose residues (alpha 1-3)-linked to peripheral N-acetylglucosamine residues. These results indicate that the increase in the number of antennae in transferrin glycans synthesized by the hepatocarcinoma cell line is much more pronounced than in liver diseases such as alcoholic cirrhosis and that, in addition, the malignant transformation of human liver induces the presence of fucose.

Platelet serotonin content and plasma tryptophan in peri- and postmenopausal women: variations with plasma oestrogen levels and depressive symptoms.

Platelet serotonin content was measured by high pressure liquid chromatography in 56 peri- and postmenopausal women, in order to study variations of this parameter with hormonal status and depressive mood symptoms. Clinical symptoms were assessed by a self-report depression symptom scale (CES-D of NIMH). Thirty-eight women with a score of 16 or more were considered as presenting depressive symptoms (mean score +/- SD = 28.8 +/- 10.5), while the others formed the control group (n = 18, score = 4.4 +/- 4.2). Platelet serotonin contents were significantly lower in the 'depressed' group (0.302 +/- 0.010 vs. 0.366 +/- 0.020 nmol 10(-8) platelets, means + SEM, P less than 0.001 by Mann-Whitney U-test). In 'depressed' women who had been treated for one or more depressive episodes, platelet 5-HT contents (0.283 +/- 0.023, n = 18, P less than 0.01) were significantly lower with respect to controls. In patients without previous episodes of depression, serotonin expressed in nmol 10(-8) platelets did not differ significantly from controls but serotonin expressed in nmol ml-1 of blood was slightly lower than control values (0.890 +/- 0.085, n = 20 vs. 1.088 +/- 0.090 nmol ml-1, n = 18, P less than 0.02). Platelet serotonin content was positively correlated to plasma oestrone and oestradiol concentrations among the control group but not in the 'depressed' group.(ABSTRACT TRUNCATED AT 250 WORDS)

Activation of platelets by microfibrils and collagen. A comparative study.

Previous works demonstrated that microfibrils stimulate blood platelets to aggregate. The present study compares the activation of platelets by human placental and bovine aortic microfibrils and by type III collagen. We studied the morphological changes occurring in in platelets during their activation and aggregation, as well as the kinetics of the release reaction and thromboxane B2 formation. As for collagen, the microfibrils-induced platelet aggregation followed a lag phase, during which progressive emission of pseudopodes and centralization of organelles occurred. Aggregation was associated with secretion of beta-thromboglobulin and adenylic adenylic nucleotides, and with formation of thromboxane B2; it was established that the kinetics of secretion and the aggregation curve were parallel. Microfibrils-induced aggregation was also inhibited by ethylenediamine tetraacetic acid, creatine phosphate-creatine phosphokinase, and aspirin, showing that it was calcium-dependent and required a secretion of ADP and formation of endoperoxide and thromboxane. The response to microfibrils was much more rapid than to collagen; placental microfibrils reacted faster than aortic microfibrils. The requirement of plasma in the microfibrils platelets interaction was confirmed: 10 microliters is the minimal amount of plasma necessary for an aggregation of platelets in 400 microliters of buffer. This fact supports the idea of the existence of two different pathways in the interaction between platelet and the subendothelium, depending on the vascular structure (microfibrils or collagen) involved, even though the sequence of events leading to the formation of an aggregate is similar.