Seminal vesicles ultrasound features in a cohort of infertility patients.

OBJECTIVES: Previous studies concerning ultrasound evaluation of the seminal vesicles (SV) were performed on a limited series of subjects, and considered few parameters, often only before ejaculation and without assessing the patients' sexual abstinence. The aim of this study was to evaluate the volume and the emptying characteristics of the SV and their possible correlations with scrotal and transrectal ultrasound features. METHODS: The SV of 368 men seeking medical care for couple infertility were evaluated by ultrasound. All patients underwent, during the same ultrasound session, scrotal and transrectal evaluation, before and after ejaculation, and the ejaculate was subjected to semen analysis. A new parameter, SV ejection fraction, calculated as: [(SV volume before ejaculation - SV volume after ejaculation)/SV volume before ejaculation] × 100, was evaluated. RESULTS: After adjusting for sexual abstinence and age, both pre-ejaculatory SV volume and SV ejection fraction were positively associated with ejaculate volume. As assessed by receiver operating characteristic curve, a cut-off for SV ejection fraction of 21.6% discriminates subjects with normal ejaculate volume (≥1.5 ml) and pH (≥7.2 ml) with both sensitivity and specificity equal to 75%. Subjects with SV ejection fraction of <21.6% more often had a higher post-ejaculatory SV volume and ejaculatory duct abnormalities. Furthermore, a higher post-ejaculatory SV volume was associated with a higher prostate volume and SV abnormalities. Higher epididymal and deferential diameters were also detected in subjects with a higher post-ejaculatory SV volume or reduced SV ejection fraction. No association between SV and testis ultrasound features or sperm parameters was observed. Associations with SV ejection fraction were confirmed in nested 1:1 case-control analysis. CONCLUSIONS: The SV contribute significantly to the ejaculate volume. A new parameter, SV ejection fraction, could be useful in assessing SV emptying. A SV ejection fraction of <21.6% was associated with prostate-vesicular and epididymal ultrasound abnormalities.

Ultrasonographic and clinical correlates of seminal plasma interleukin-8 levels in patients attending an andrology clinic for infertility.

This study was aimed at evaluating the association between seminal plasma interleukin-8 (sIL-8) and colour-Doppler ultrasound (CDU) characteristics of the male genital tract in a series of patients fulfilling the criteria of male accessory gland infections (MAGI). Of 250 subjects seeking medical care for couple infertility, 79 (mean age: 36.4 ± 7.5 years) met the criteria of MAGI and scored higher than the rest of the sample on the National Institutes of Health-Chronic Prostatitis Symptom Index score. All patients underwent simultaneous hormone evaluation and seminal analysis (including sIL-8), along with scrotal and transrectal CDU before and after ejaculation. After adjusting for age, sIL-8 in patients with MAGI was significantly related to several abnormal semen and CDU parameters. In particular, leucocytospermia was closely associated with sIL-8. Ejaculate volume, unlike other semen or hormonal parameters, was negatively associated with sIL-8. When scrotal CDU was performed, sIL-8 was positively related to CDU inhomogeneous, hypo-echoic, hyper-echoic epididymis and to epididymal calcifications. In addition, a positive correlation among sIL-8, hyperaemic epididymis and an increased size of epididymal tail was found. When transrectal CDU was performed, an association among sIL-8 and hyper-echoic seminal vesicles, dilated ejaculatory ducts and duct calcifications was also observed. Finally, sIL-8 was positively related to prostate CDU abnormalities such as calcifications, inhomogeneous/hypo-echoic texture, hyperaemia and high arterial blood flow. No association was found with testis parameters. In conclusion, sIL-8 levels in patients with MAGI are associated with several parameters and CDU abnormalities of epididymis, seminal vesicles, ejaculatory ducts and prostate, but not of the testis. Furthermore, sIL-8 positively correlates with CDU signs of ejaculatory duct inflammatory subobstruction.

Elevated body mass index correlates with higher seminal plasma interleukin 8 levels and ultrasonographic abnormalities of the prostate in men attending an andrology clinic for infertility.

BACKGROUND: Obesity is associated with a systemic, low-grade inflammatory state. Although the relationship between obesity and semen parameters or prostate diseases has been previously investigated, the association between body mass index (BMI), prostate inflammatory diseases and color- Doppler ultrasound (CDU) of the male genital tract (MGT) has been poorly studied. AIM: To evaluate the association between BMI and CDU features of the MGT, signs and symptoms of prostate inflammation, semen parameters. MATERIALS/SUBJECTS AND METHODS: We studied 222 men seeking medical care for couple infertility. According to the World Health Organization classification, subjects were divided into 3 groups: normal weight (no.=131, BMI=18.5-24.9 kg/m2), overweight (no.=71, BMI=25.0-29.9 kg/m2), obese (no.=20, BMI≥30.0 kg/m2). All patients underwent simultaneous testosterone evaluation and seminal analysis, including interleukin 8 (sIL-8), along with scrotal and transrectal CDU, before and after ejaculation. Prostatitis symptoms were evaluated by National Institutes of Health- Chronic Prostatitis Symptom Index questionnaire. RESULTS: After adjusting for age and testosterone levels, higher BMI was significantly related to higher prostate volume and several CDU features of the prostate, including macro-calcifications, inhomogeneity, higher arterial peak systolic velocity (the latter adjusted also for blood pressure), but not with abnormalities of testis, epididymis, seminal vesicles. Furthermore, higher BMI and BMI class were significantly related to higher sIL-8, a reliable surrogate marker of prostate inflammatory diseases, even after adjustment for age. Conversely, no associations among BMI, clinical symptoms of prostatitis or semen parameters were observed. CONCLUSIONS: Subjects with higher BMI might develop CDU and biochemical signs suggestive of prostate inflammation, although not clinically overt.

Potential role of interleukin-1 as the trigger for diffuse intravascular coagulation in acute nonlymphoblastic leukemia.

Abnormalities of coagulation are common in patients with acute nonlymphoblastic leukemia, although the mechanisms involved are unclear, except in a few cases. To investigate the pathogenesis of this coagulopathy, suspensions of purified leukemic cells were prepared and tested for procoagulant activity. Neither the leukemic cells nor their supernatants directly accelerated the clotting of plasma. Since the leukemic cells did not possess direct procoagulant activity, their ability or inability to elaborate a mediator of cellular coagulant properties, interleukin-1, was studied. Leukemic cells from patients with coagulopathy elaborated interleukin-1, and addition of phytohemagglutinin increased interleukin-1 release. In contrast, no interleukin-1 was released, before or after stimulation with phytohemagglutinin, from leukemic cells from patients without coagulopathy. Leukemic cells from another group of patients with abnormalities of coagulation released interleukin-1 only after phytohemagglutinin treatment. In terms of the coagulation mechanism, interleukin-1 containing supernatants from leukemic cell cultures induced the procoagulant receptor tissue factor, a co-factor in the initiation of coagulation, on the endothelial cell surface. There was coordinate suppression of the anticoagulant endothelial cell receptor thrombomodulin, a co-factor for the antithrombotic protein C pathway. Antibody to interleukin-1 prevented these changes in cellular coagulant properties. Taken together, these changes result in a shift in the balance of endothelial cell coagulant properties to an activated state in which mechanisms promoting procoagulant reactions on the vessel surface predominate. Synthesis and release of the mediator interleukin-1 by leukemic cells thus defines a new mechanism through which malignant cells can potentially activate the coagulation mechanism.

Early haemostatic modifications following cryopreserved graft infusion.

The nature of the graft used for the rescue of patients undergoing autologous bone marrow transplantation is that of a complex mixture of pharmacological agents and cellular debris known to have a number of effects on the haemostatic system. The present study was undertaken to evaluate the occurrence and the degree of haemostatic alterations during and immediately following graft infusion in 24 patients suffering from haematological malignancies. On day 0, before graft infusion, the majority of patients appeared with laboratory signs of enhanced thrombin generation, platelet activation, and endothelial damage, most likely due to the conditioning regimen. However, the graft infusion per se was accompanied in the short term by a further increment of some parameters indicating a thrombotic risk (as thrombin-antithrombin complex, beta-thrombo globulin, platelet factor four, and von Willebrand factor antigen, together with a concomitant prolongation of partial thromboplastin time and a reduction of prothrombin time. In contrast there was no further modification of antithrombin III or protein C levels nor an increase in fibrinopeptide A levels. We hypothesize that complex interactions between agents contained in the graft mixture and host haemostatic system are involved in the pathogenesis of the haemostatic alterations which followed cryopreserved graft infusion; however, in our series, these were not accompanied by clinical signs of thrombotic or haemorrhagic events.

Protein content and factor VIII complex in untreated, treated and monoclonal factor VIII concentrates.

Replacement therapy with clotting factor concentrates may expose the recipients not only to virus contamination but also to continuous stimulation of the immune system by repeated infusions of allogenic proteins. Concentrate purity is now a very important prerequisite to be taken into account in choosing what product can better meet the patient's needs. We compared protein content (albumin, fibrinogen, fibronectin, immunoglobulins) and factor VIII:C/vWF:Ag complex in untreated, treated and monoclonal factor VIII concentrates. Protein content is dramatically decreased in new treated ultrapure concentrates. Improved traditional fractionation methods allowed to obtain very high Factor VIII specific activity. New fractionation methods with immunoaffinity chromatography by means of monoclonal antibodies can give highly pure concentrates even if deliberately added albumin decreases factor VIII specific activity in final formulation. Otherwise monoclonal concentrates show a very high specific activity in terms of fibrinogen and immunoglobulin content, which, unlike albumin, are affecting the immune system in hemophiliacs.

Pharmacokinetics, thrombogenicity and safety of a double-treated prothrombin complex concentrate.

The pharmacokinetic profile, the thrombogenicity and the virus safety of Preconativ, a PCC subjected both to virus removal procedure and dry-heat treatment were studied. Preconativ is produced from plasma pool, negative both for HBsAg and for antibodies to HIV. To further reduce the risk of virus transmission, the manufacturing process includes hydrophobic gel chromatography and dry-heat treatment at +68 degrees C for 48 hours. Nine patients with hemophilia B participated in a single dose, pharmacokinetic study. The decay curves of factor IX clotting activity were evaluated by model-independent methods. The Clearance and the Mean Residence Time were very similar to those previously reported for untreated PCC. The Volume of Distribution Area and In Vivo Recovery resulted inversely correlated and respectively larger and smaller than those of untreated PCC. A slight fall in platelet count and Antithrombin III level and an increase of Beta-Thromboglobulin and Fibrinopeptide A concentration were found, indicating a clear-cut activation of the coagulation process during the first hours following Preconativ administration. Seven patients (2 of the ones enrolled in the pharmacokinetic study) were completely fulfilling the SSC-ISTH criteria for virus safety prospective study. The follow up of these patients did not show any transaminases elevation or seroconversion against HBV, HCV or HIV. These findings did not change over a 3-5 year follow up in 3 out of 7 patients, repeatedly infused with Preconativ.

Uteroglobin and transglutaminase modulate human sperm functions.

During the process of capacitation, spermatozoa undergo significant changes in membrane composition, including removal of decapacitating factors (DFs), which are present in seminal plasma, that lead to increased sensitivity to physiological stimuli of the acrosome reaction. In the present study we investigated the presence, localization, and effects on human spermatozoa of 2 proteins of seminal plasma origin, uteroglobin (UG) and transglutaminase (TG). These 2 proteins interact with one another because TG promotes covalent links of UG to sperm surface proteins. We found that UG is localized around the entire surface of ejaculated human sperm, whereas TG is predominantly localized in the neck. FACScan analysis confirmed the surface localization of both antigens and demonstrated that swim-up selection of spermatozoa was associated with a significant reduction in the contents of the 2 substances when compared with unselected samples. Western blot analysis of UG in total sperm lysates confirmed the lower content of the protein in swim-up-selected sperm. Swim-up-selected sperm were characterized by their ability to undergo a spontaneous, time-dependent increase of capacitation-characteristic chlortetracycline pattern of fluorescence and increase in responsiveness to progesterone. Such changes were not observed in unselected sperm. Exogenous addition of TG, together with recombinant rabbit UG, prevented the spontaneous increase in responsiveness to progesterone (acrosome reaction and intracellular calcium) at 24 hours in swim-up-selected sperm, suggesting the occurrence of a capacitation-inhibiting activity of the 2 substances. In addition, we found that endogenous UG and TG contents, as determined by FACScan analysis, were negatively correlated (P < .0001) with sperm motility and that exogenous addition of the 2 substances resulted in a substantial reduction of progressive motility (P < .01). Collectively, these data indicate that TG and UG represent 2 DFs, and contribute to understanding the biochemical mechanisms that characterize the process of capacitation.

Functional and ultrastructural features of DNA-fragmented human sperm.

The functional significance of deoxyribonucleic acid (DNA) fragmentation in ejaculated human sperm is unclear. In this study the extent of DNA strand breakage in swim-up selected spermatozoa was evaluated by terminal deoxynucleotidyl transferase-mediated fluorescein-dUTP nick end labeling (TUNEL)-coupled flow cytometry and correlated with several functional and morphological sperm parameters. The extent of DNA fragmentation (mean = 11.07%+/-8.00%, range = 0.79%-42.64%, n = 140) was positively related to abnormal morphology and associated with defects of the sperm tail. A negative correlation was found between DNA breakage and progressive motility. When a stepwise multiple linear regression model was used to analyze the relationship between DNA fragmentation and the aforementioned parameters, only motility results were included in the model. The presence of spermatozoa showing submicroscopic characteristics resembling those of somatic apoptosis has been reported in human ejaculate. To verify whether sperm DNA fragmentation was associated with the presence of such apoptotic-like cells, we performed electron microscopy and TUNEL-coupled flow cytometry in a limited number of sperm samples (n = 24). Although we did not observe any significant relationship between DNA breakage and the characteristics that are suggestive of apoptosis, an association was found with several ultrastructural features, indicating an impaired motility. Hence, we conclude that in ejaculated sperm, DNA fragmentation does not correspond to the apoptosis-like phenomenon and that it is associated with defects of motility.

Does ergometric stress test induce a procoagulative condition in patients with previous myocardial infarction?

A regularly scheduled physical training program seems to have antithrombotic effects. Moreover, the hemostatic changes occurring in patients with coronary artery disease during acute exercise have not been clearly elucidated. Since stress testing is routinely performed in clinical cardiology, it would be helpful to assess whether patients with coronary artery disease are exposed to acute coronary thrombosis during or soon after sustained physical exercise. This study was designed to evaluate the effect of acute physical exercise (stress test by bicycle ergometer) on blood coagulation in a group of patients with previous myocardial infarction, and to determine whether the antithrombotic therapy commonly administered favorably influences hemostatic equilibrium. Our results suggest that exercise testing is not harmful to patients with previous myocardial infarction in regard to hemostasis and fibrinolysis and that antithrombotic therapy reduces postexercise increase in platelets.

Hemodialysis with defibrotide: effects on coagulation parameters.

In a crossover study conducted with eight uremic patients maintained on hemodialysis, the Authors compared the effects of heparin (100 IU/kg at the start of dialysis) and defibrotide (400 mg at the start, repeated at 2 hours of ongoing dialysis) on the parameters of blood coagulation (VIII:C, AT III, TAT, PC antigen and activity, PS, and FPA), each being assessed before dialysis and at 2, 3 and 4 hours of the ongoing procedure. Heparin-assisted dialysis resulted in a significant rise of VIII:C and AT III; with defibrotide, instead, there was evidence of thrombin activation (increased FPA and TAT). PC levels were raised with both dialysis modalities; however, PC activity and PS levels were increased only in defibrotide-assisted dialysis. There were no adverse reactions or evidence of fibrin formation. These results confirm the antithrombotic activity of defibrotide in the course of dialysis and indicate that this action is independent of thrombin neutralization.

Aspects of biocompatibility of two different dialysis membranes: cuprophane and polysulfone.

Intradialytic hypoxemia, leukopenia and coagulation system activation were monitored in 9 uremic patients during hemodialysis with cuprophane (Cu) and polysulfone (Psf) membranes, using the following parameters: polymorphonuclear count (PMN), elastase alpha-1 proteinase inhibitor (EI-alpha 1PI) complex, platelet count, beta-thromboglobulin (BTG), fibronectin (FN) and arterial oxygen tension (PaO2). Our results indicate that 1) intradialytic hypoxemia observed with both membranes does not seem to be exclusively related to the well-known membrane-dependent leukopenia; 2) platelet activation, as demonstrated by the plasma BTG increase, appears to be an exclusive cellulosic membrane-related phenomenon; 3) at the same time platelet activation seems to be the major factor responsible for high FN levels, the highest FN levels occurring concurrently with the lowest platelet count.

Seminal, clinical and colour-Doppler ultrasound correlations of prostatitis-like symptoms in males of infertile couples.

'Prostatitis-like symptoms' (PLS) are a cluster of bothersome conditions defined as 'perineal and/or ejaculatory pain or discomfort and National Institutes of Health-Chronic Prostatitis Symptom Index (NIH-CPSI) pain subdomain score ≥4' (Nickel's criteria). PLS may originate from the prostate or from other portions of the male genital tract. Although PLS could be associated with 'prostatitis', they should not be confused. The NIH-CPSI is considered the gold-standard for assessing PLS severity. Although previous studies investigated the impact of prostatitis, vesiculitis or epididymitis on semen parameters, correlations between their related symptoms and seminal or scrotal/transrectal colour-Doppler ultrasound (CDU) characteristics have not been carefully determined. And no previous study evaluated the CDU features of PLS in infertile men. This study was aimed at investigating possible associations among NIH-CPSI (total and subdomain) scores and PLS, with seminal, clinical and scrotal/transrectal CDU parameters in a cohort of males of infertile couples. PLS of 400 men (35.8 ± 7.2 years) with a suspected male factor were assessed by the NIH-CPSI. All patients underwent, during the same day, semen analysis, seminal plasma interleukin 8 (sIL-8, a marker of male genital tract inflammation), biochemical evaluation, urine/seminal cultures, scrotal/transrectal CDU. PLS was detected in 39 (9.8%) subjects. After adjusting for age, waist and total testosterone (TT), no association among NIH-CPSI (total or subdomain) scores or PLS and sperm parameters was observed. However, we found a positive association with current positive urine and/or seminal cultures, sIL-8 levels and CDU features suggestive of inflammation of the epididymis, seminal vesicles, prostate, but not of the testis. The aforementioned significant associations of PLS were further confirmed by comparing PLS patients with age-, waist- and TT-matched PLS-free patients (1 : 3 ratio). In conclusion, NIH-CPSI scores and PLS evaluated in males of infertile couples, are not related to sperm parameters, but mainly to clinical and CDU signs of infection/inflammation.

Seminal, ultrasound and psychobiological parameters correlate with metabolic syndrome in male members of infertile couples.

Metabolic syndrome (MetS) is a diagnostic category which identifies subjects at high risk for diabetes and cardiovascular diseases, erectile dysfunction (ED) and male hypogonadism. However, MetS impact on male infertility has been poorly studied. We systematically evaluated possible associations between MetS and clinical characteristics in men with couple infertility. Out of 367 consecutive subjects, 351 men without genetic abnormalities were studied. MetS was defined according to the International Diabetes Federation&American Heart Association/National Heart,Lung, and Blood Institute classification. All men underwent physical, hormonal, seminal and scrotal ultrasound evaluation. Erectile and ejaculatory functions were assessed by International Index of Erectile Function-15 erectile function domain (IIEF-15-EFD) and Premature Ejaculation Diagnostic Tool (PEDT), respectively, while psychological symptoms by Middlesex Hospital Questionnaire. Out of 351 patients, 27 (7.7%) fulfilled MetS criteria. Among ultrasound features, in an age-adjusted logistic model, only testis inhomogeneity was significantly associated with increasing MetS factors (HR = 1.36 [1.09-1.70]; p < 0.01). In an age-adjusted model, MetS was associated with a stepwise decline in total testosterone (TT) (B = -1.25 ± 0.33; p < 0.0001), without a concomitant rise in gonadotropins. At univariate analysis, progressive motility and normal morphology were negatively related to the number of MetS components (both p < 0.0001), but when age and TT were introduced in a multivariate model, only sperm morphology retained a significant association (B = -1.418 ± 0.42; p = 0.001). The risk of ED (IIEF-15-EFD score <26) increased as a function of the number of MetS factors, even after adjusting for age and TT (HR = 1.45[1.08-1.95]; p < 0.02). No association between PEDT score and MetS was observed. Finally, after adjusting for age and TT, somatization and depressive symptoms were associated with increasing MetS components (B = 0.66 ± 0.03, p < 0.05; B = 0.69 ± 0.03, p < 0.02; respectively). In conclusion, in men with couple infertility, MetS is associated with hypogonadism, poor sperm morphology, testis ultrasound inhomogeneity, ED, somatization and depression. Recognizing MetS could help patients to improve not only fertility but also sexual and overall health.

High variability in results of semen analysis in andrology laboratories in Tuscany (Italy): the experience of an external quality control (EQC) programme.

We report the results of the first three trials of an external quality control (EQC) programme performed in 71 laboratories executing semen analysis in Tuscany Region (Italy). At the end of the second trial, participants were invited to attend a teaching course illustrating and inviting to adhere to procedures recommended by WHO (V edition). Results of the first three trials of the EQC documented a huge variability in the procedures and the results. The highest variability was found for morphology (CV above 80% for all the trials), followed by count (CV of about 60% for all the trials) and motility (CV below 30% for all the trials). When results of sperm count and morphology were divided according to the used method, mean CV values did not show significant differences. CV for morphology dropped significantly at the third trial for most methods, indicating the usefulness of the teaching course for morphology assessment. Conversely, no differences were observed after the course for motility and for most methods to evaluate count, although CV values were lower at the second and third trial for the laboratories using the Burker cytometer. When results were divided according to tertiles of activity, the lowest mean bias values (difference between each laboratory result and the median value of the results) for count and morphology were observed for laboratories in the third tertile (performing over 200 semen analysis/year). Of interest, mean bias values for concentration dropped significantly at the third trial for low activity laboratories. In conclusion, lack of agreement of results of semen analysis in Tuscany is mainly because of the activity and the experience of the laboratory. Our study points out the importance of participating in EQC programmes and periodical teaching courses as well as the use of WHO recommended standardized procedures to increase precision and to allow the use of WHO reference values.

Pretransplant factor XII levels correlate with prognosis in patients undergoing autologous graft for hematological malignancies.

A retrospective analysis of data collected in a previous study suggested that pre-conditioning levels of factor XII might have prognostic value in autologous graft recipients. In order to confirm whether pre-transplant factor XII (pFXII) levels could be correlated with outcome, seventy-six (35 autologous and 41 allogeneic) transplant recipients were prospectively evaluated. A significant direct relationship was found between pFXII levels and both overall and disease-free survival in the autologous grafts, but not in the allogeneic ones. Although the molecular mechanisms of this relationship still need to be clarified, these data seem to justify larger efforts to confirm whether factor XII (FXII) assay should be used in pre-transplant evaluation of patients.

Phosphatidylinositol 3-kinase inhibition enhances human sperm motility.

BACKGROUND: The number of spermatozoa with forward motility after capacitation procedures represents the limiting factor for application of IVF versus intracytoplasmatic sperm injection (ICSI) procedure in cases of oligoasthenozoospermia. The possibility of increasing this number may thus be of help to the patient. A complex array of signalling pathways is involved in the regulation of sperm motility and recent data pointed out an important role for kinase/phosphatase-regulated phosphorylation of proteins. Here, we investigated the role of phosphatidylinositol 3-kinase (PI3K), a lipid and protein kinase involved in the regulation of several biological aspects of somatic cells, on human sperm motility by using the specific PI3K inhibitor LY294002. METHODS AND RESULTS: We demonstrated that in-vitro incubation of swim-up selected or unselected human spermatozoa with LY294002 determined an increase of percentage forward motility in all the treated samples. The effect was dose-dependent with an EC(50) of 1.09 +/- 0.54 micromol/l. LY294002 also increased sperm movement characteristics and hyperactivation as evaluated by computer-assisted motion analyser. The compound was also able to overcome the detrimental effect of hydrogen peroxide and lithium chloride on sperm motility. CONCLUSIONS: Our results suggest a negative role for PI3K in the development and maintenance of sperm motility and suggest a possible use of PI3K inhibitors to enhance motility in cases of asthenozoospermia.

Multi-variate analysis of factors governing the pharmacokinetics of exogenous factor VIII in haemophiliacs.

The pharmacokinetics of Factor VIII was evaluated by mathematical modeling in a large-scale study in 62 haemophilia-A subjects, in whom 137 plasma Factor VIII-time curves were measured during single dose (n = 87) and repeated-dose (n = 47) treatments for prophylaxis or minor bleeding episodes. The pharmacokinetic parameters [mean (SD)] estimated from single-dose curves were: clearance 3.85 ml.h-1.kg-1, volume of distribution 58.2 ml.kg-1, mean residence time 15.9 h. Parameters calculated from repeated-dose curves were: clearance 3.93 ml.h-1.kg-1, volume of distribution 61.8 ml.kg-1, and half-life 12.2 h. In patients with mild haemophilia, pharmaco-statistical analysis revealed that the endogenous synthesis of Factor VIII was constant and was not influenced by the administration of exogenous Factor VIII. The coefficient of variation for intra-individual variability of Factor VIII kinetics (estimated according to the Standard Two-Stage method) was 20.7% in single-dose curves and 23.2% in repeated-dose curves.

Single-dose pharmacokinetics of factor IX evaluated by model-independent methods.

We studied the pharmacokinetic data of 13 subjects with hemophilia B treated with a single-dose of a Factor IX concentrate (Bebulin TIM2, N = 9; Preconativ, N = 4). The decay curves of Factor IX were evaluated by model-independent methods and the following pharmacokinetic parameters (mean +/- SD) were estimated: clearance (ml/h/kg) = 4.99 +/- 2.01; mean residence time (h) = 22.9 +/- 10.6; volume of distribution (ml/kg) = 99.9 +/- 35.5. The in vivo recovery (59.8% +/- 16.9%) was found to be inversely correlated with the volume of distribution. No significant difference in the pharmacokinetic parameters was found between patients treated with Preconativ and those treated with Bebulin. A model-dependent compartmental evaluation of the 13 decay curves showed that the two-compartment model was better than the one-compartment model in 7 cases (53.8%), but the improvement of fit resulting from the two-compartment model was statistically significant in only 2 cases (15.4%).