Study of the mechanism of intumescence in fire retardant polymers. Part VI: Mechanism of ester formation in ammonium polyphosphate - pentaerythritol mixtures

It is shown that, on heating ammonium polyphosphate-pentaerythritol mixtures, phosphoric ester bonds are formed first by alcoholysis of the polyphosphate chain. Further intramolecular alcoholysis and/or esterification leads to cyclic pentaerythritol phosphate structures inserted in the polyphosphate chains. Evidence is also given of intermolecular dehydration of pentaerythritol in mixtures with a large excess of alcoholic hydroxy groups over phosphorus atoms. The intumescent behaviour of the mixtures is discussed in relation to the final structure of the product of reaction which depends on the composition of the original mixture

Determinants of short term recurrence rate of endometriosis

Objective: To analyse the frequency and the determinants of recurrence rate of clinically detectable endometriosis. Study design: Prospective cohort multicenter study. Eligible for the study were all women observed for the first time during the period January–June 1998 at the participating centres with a laparoscopically confirmed first diagnosis of endometriosis. After diagnosis, patients were treated according to standard care of each centre and desire for pregnancy. The protocol required all women to be followed up at the centre each year for 2 years with a clinical examination, an ultrasound pelvic examination and a CA125 assay, unless pregnancy occurred. Second look laparoscopy was performed on a clinical basis. Results: A total of 311 women (median age 36 years) entered the study. The two-year recurrence rate was 5.7% among cases stage I-II and 14.4% among stage III–IV (x2 1 adjusted for indication for surgery, p < 0.05). The recurrence rates tended to increase with age, being 4.6% among women aged 20–30 and 13.1% among women aged >30, but this finding was not statistically significant. Conclusion: The recurrence rate of clinically detectable endometriosis tends to be higher in older women with advanced stages of the disease and lower in women with infertilit

Ablation of lesions or no treatment in minimalmild endometriosis in infertile women: a randomized trial

Abstract In order to analyse the efficacy of resection/ablation of minimal/mild endometriotic lesions for improving fertility, we conducted a randomized clinical trial. Eligible patients were women aged 64 36 years who were trying to conceive and had a laparoscopically confirmed diagnosis of minimal/mild endometriosis (stage I or II of the revised American Fertility Society classification) and otherwise unexplained infertility for 65 2 years. Eligible women were randomly assigned to resection or ablation of visible endometriosis (54 patients) or diagnostic laparoscopy only (47 patients). After laparoscopy women tried to conceive spontaneously for 1 year (follow-up period). A total of five women withdrew from the study: three for personal reasons, and two were lost to follow-up. Considering 51 women in the resection/ablation and 45 in the no-treatment group who ended the follow-up period, 12 (24%) in the resection/ablation group and 13 (29%) in the no treatment group conceived; the difference was not significant. Two spontaneous abortions were observed in the resection/ablation group and three in the no-treatment one. Thus the 1 year birth rate was 10 out of 51 women (19.6%) in the resection/ablation group and 10 out of 45 women (22.2%) in the no-treatment group. In conclusion, the results of this study do not support the hypothesis that ablation of endometriotic lesions markedly improves fertility rates

Oral contraceptive use and risk of endometriosis. Italian Endometriosis Study Group.

Objective. To analyse the association between use of oral contraception and risk of pelvic endometriosis. Design. We compared use of oral contraception in women with and without endometriosis. Participants. Eligible for the study were women with primary or secondary infertility (n = 393) or chronic pelvic pain (n = 424), requiring laparoscopy, consecutively observed between September 1995 and January 1996 in 15 obstetrics and gynaecology departments in Italy. Results. Out of the 817 women included in the study, 345 had a diagnosis of endometriosis; 164 (47.5%) women with endometriosis and 139 (29.4%) without the disease reported ever using oral contraception. In comparison with never users the estimated odds ratios (OR) of endometriosis were 1.8 (95% CI 1.0-3.3) in current users and 1.6 (95% CI 1.1-2.4) in ex-users. No clear relation emerged between duration of oral contraceptive use and risk of endometriosis. In comparison with never users, the OR was 1.8 (95% CI 1.1-3.0) for women reporting their last use of oral contraception < 5 years before interview and 1.5 (95% CI 0.9-2.5) for those reporting their last use 65 5 years before interview. Conclusions. The study suggests that oral contraception is associated with an increased risk of endometriosis but this finding is based on a selected population and cannot generalised to all women with endometriosis

Risk factors for pelvic endometriosis in women with pelvic pain or infertility

Objective: The objective of the study was to analyse the relationship between selected characteristics and risk of pelvic endometriosis. Study design: Eligible for the study were 817 women with primary or secondary infertility or pelvic pain requiring laparoscopy. Of these, 393 were included for infertility and 424 for pelvic pain. Results: A total of 345 (42.2%) had a diagnosis of endometriosis and 472 did not have the disease. Multiparous women had endomertriosos less frequently than nulliparous, the estimated odds ratios (OR) were respectively 0.9 (95% confidence interval, CI, 0.5-1.6) and 0.4 (95% CI 0.2-0.7) in women reporting one and two or more births. In comparison with women reporting no spontaneous abortion, the estimated OR was 0.3 (95% CI 0.2-0.5) in those who reported greater than or equal to 1 miscarriage. In comparison with women reporting menstrual cycles lasting greater than or equal to 25 days subjects with totally irregular menstrual cycles had a reduced risk of endometriosis (OR 0.6, 95% CI 0.3-0.9). No significant association emerged between smoking, age at menarche and risk of endometriosis. Conclusions: this study confirms, with a different methodological approach to previously published studies, that multiparity, a history of abortion and lifelong irregular menstrual pattern decrease the risk of endometriosis in women with pelvic pain and infertility. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved