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Biomedical subjects

A Tripodi

Publications and source records attributed to A Tripodi.

At least 19 recordsLinked to original sources
PubMed2006

International collaborative study for the calibration of a proposed international standard for thromboplastin, rabbit, plain.

BACKGROUND: A preparation of rabbit brain thromboplastin, provisionally coded 04/162, is proposed as a candidate for the World Health Organization (WHO) International Standard (IS) for thromboplastin (rabbit, plain), meant to replace the IS coded RBT/90 (rabbit, plain), stocks of which are now exhausted. RESULTS: The preparation was calibrated in an international collaborative study involving 21 laboratories from 13 countries and the calibration was performed against the existing WHO-IS (i.e. rTF/95 and OBT/79) and other Certified Reference Materials from the Institute for Reference Materials and Measurements of the European Commission (i.e. CRM149 S) and from the European Action on Anticoagulation (i.e. EUTHR-01). An additional candidate rabbit brain thromboplastin coded as 04/106 was also included in the study. On the basis of predefined criteria (the within- and between-laboratory precision of the calibration and the conformity to the calibration model), 04/162 was the preferred candidate. CONCLUSIONS: The assigned International Sensitivity Index value was 1.15 and the inter-laboratory SD and coefficient of variation were 0.057% and 4.9%, respectively.

Animals↗
PubMed2006

Leptin: pharmacological aspects in gynecology.

Hematic levels of leptin vary in relation to numerous metabolic factors and are able to interact in perfect synchrony with the hormones involved in the hypothalamus-pituitary-ovarian axis during the various phases of the reproductive cycle. In general it is maintained that the complex and multiple action mechanisms of leptin need to be clarified by further in-depth research studies. It is likely that valid pharmacological applications of leptin will be found for human use although it is too premature to talk about concrete pharmacological answers and to formulate the relative complete technical protocols. In medicine the therapeutic use of leptin for humans has been reported in only a few cases. In fact human recombinant leptin has already been administered in gynecology for hypothalamic amenorrhea with precise protocols. In addition, very recent studies have provided the basis for new strategies to be developed concerning the use of leptin to fight multiple sclerosis. At present there are considerable technical and economic problems in the production of leptin on a large scale. Most likely these problems will be overcome in the foreseeable future, and will involve new techniques related to genetics, cellular reprograming, and stem cells. In fact, new pharmacogenetic research has provided encouraging results for the production in industrial quantities of a more effective and fail-proof leptin. Even considering that norms have not yet been proposed for pharmacological interventions with leptin for use directly on humans, in our work we have studied by immunohistochemistry methods the distribution of leptin and its receptor (Ob-R) in the ovaries of the female dog as a biological model, in the pre- and postpubertal phases and in other phases of the ovarian cycle. Given the hypothesis that the information obtained from immunohistochemical localization of the hormone and its receptor in various ovarian structures is transferable to humans, it could be useful to define therapeutic protocols based on the effective role of leptin and its receptor in folliculogenesis.

Animals↗
PubMed2005

European Concerted Action on Anticoagulation. A multicentre calibration study of WHO international reference preparations for thromboplastin, rabbit (RBT/90) and human (rTF/95).

A 10 centre calibration was performed after six years to determine the international sensitivity index (ISI) of rTF/95 relative to RBT/90, and to assess any international normalised ratio (INR) bias compared with the original multicentre calibration. After exclusion of one outlying centre, the follow up calibration gave a mean ISI for rTF/95 of 0.99, which although a small difference, is significantly greater than the mean ISI of 0.94 obtained previously. The change in ISI for international reference preparation (IRP) rTF/95 relative to RBT/90 would lead to a slight bias in INR for human compared with rabbit thromboplastins. At a theoretical INR of 3.0, the INR bias is 6.0%, and this is below the accepted 10% level of clinical relevance. Ongoing stability monitoring of World Health Organisation thromboplastin IRP is advised.

Animals↗
PubMed2004

Measurement of von Willebrand factor cleaving protease (ADAMTS-13): results of an international collaborative study involving 11 methods testing the same set of coded plasmas.

BACKGROUND: ADAMTS-13 is a von Willebrand factor (VFW)-cleaving protease. Its congenital or acquired deficiency is associated with thrombotic thrombocytopenic purpura (TTP) and more rarely with the hemolytic uremic syndrome. We report on a survey evaluating 11 methods for ADAMTS-13 measurement performed in different labs. DESIGN: Two plasmas, one normal and one from a patient with familial TTP, were mixed at the co-ordinating center to prepare 6 plasmas with 0%, 10%, 20%, 40%, 80% and 100% ADAMTS-13 levels. Each plasma was aliquoted and assembled into sets of 60 (coded from 1 to 60), each containing 10 copies of the original 6 plasmas. Plasmas were frozen and shipped in dry ice to 10 labs with a common frozen reference plasma. Laboratories were asked to measure ADAMTS-13 with their methods. Results were sent to the coordinating center for statistical analysis. RESULTS: Of the 10 methods performed under static conditions 9 were quantitative and one was semiquantitative. One method performed under flow conditions evaluated the extent of cleavage of endothelial cell-derived ultralarge VWF string-like structures and expressed results as deficient, normal, or borderline. Linearity (expected-vs-observed levels), assessed as the squared correlation coefficient, ranged from 0.98 to 0.39. Reproducibility, expressed as the coefficient of variation for repeated measurements, ranged from < 10% to 83%. The majority of methods were able to discriminate between different ADAMTS-13 levels. The majority were able to detect the plasma with 0% level and some of them to discriminate between 0% and 10%. Overall the best performance was observed for three methods measuring cleaved VWF by ristocetin cofactor, collagen binding, and immunoblotting of degraded multimers of VWF substrate, respectively. The poor interlaboratory agreement of results was hardly affected by the use of the common standard. The method performed under flow conditions identified the plasmas with 0%, 10%, 20% and 40% activity as deficient in 7, 5, 1 and 3 of the 10 replicate measurements. The plasmas with 80% and 100% were identified as normal in all of the 10 replicate measurements. CONCLUSIONS: The survey shows varied performance, but supports an optimistic view about the reliability of current methods for ADAMTS-13.

ADAM Proteins↗
PubMed2004

Guidelines on preparation, certification, and use of certified plasmas for ISI calibration and INR determination.

Reliable international normalized ratio (INR) determination depends on accurate values for international sensitivity index (ISI) and mean normal prothrombin time (MNPT). Local ISI calibration can be performed to obtain reliable INR. Alternatively, the laboratory may determine INR directly from a line relating local log(prothrombin time [PT]) to log(INR). This can be done by means of lyophilized or frozen plasmas to which certified values of PT or INR have been assigned. Currently there is one procedure for local calibration with certified plasmas which is a modification of the WHO method of ISI determination. In the other procedure, named 'direct' INR determination, certified plasmas are used to calculate a line relating log(PT) to log(INR). The number of certified plasmas for each procedure depends on the method of preparation and type of plasma. Lyophilization of plasma may induce variable effects on the INR, the magnitude of which depends on the type of thromboplastin used. Consequently, the manufacturer or supplier of certified plasmas must assign the values for different (reference) thromboplastins and validate the procedure for reliable ISI calibration or 'direct' INR determination. Certification of plasmas should be performed by at least three laboratories. Multiple values should be assigned if the differences between thromboplastin systems are greater than 10%. Testing of certified plasmas for ISI calibration may be performed in quadruplicate in the same working session. It is recommended to repeat the measurements on three sessions or days to control day-to-day variation. Testing of certified plasmas for 'direct' INR determination should be performed in at least three sessions or days. Correlation lines for ISI calibration and for 'direct' INR determination should be calculated by means of orthogonal regression. Quality assessment of the INR with certified plasmas should be performed regularly and should be repeated whenever there is a change in reagent batch or in instrument. Discrepant results obtained by users of certified plasmas should be reported to manufacturers or suppliers.

Calibration↗
PubMed2004

Pharmacological effects of melatonin on reproductive activity: experimental bioimplants with sustained-release polymeric systems.

A vast literature documents the role of melatonin in human reproductive function including: a) the relation between melatonin and the menstrual cycle in relation to the peak time of luteinizing hormone in the middle of the cycle; b) the varying concentrations of melatonin in the control of puberty; c) the fewer conceptions in some artic populations where melatonin is connected significantly to seasonal photoperiodicity during the months of the polar nights. The aim of this paper is to report our findings on the pharmacological action of this molecule on reproduction in which gonadal activity is clearly connected to photoperiodicity. We used polymer bioimplants programmed for the sustained release of melatonin for experimental gynecologic protocols. These implants had beneficial results with respect to the use of progestinics because melatonin allowed ovarian activity to be induced for at least two to three consecutive cycles with one single bioimplant. We thought it indispensable to use pharmacological systems with a sustained release because different preliminary tests showed that the half-life of melatonin is limited at maximum to two to three hours and, consequently, any other tested modalities of administration would not provide any appreciable results for our study. As a model for our research we used goats to administer melatonin via targeted programs since these animals clearly respond (even against the rule of the light/dark relation) in contrast to humans in whom response is less evident. For controls, after inserting bioimplants in the animals, we tested their efficiency in vitro and subsequently in vivo, evaluating blood parameters and pharmacological effects of melatonin occurring during the treatment. The final results proved to be interesting in relation to reproductive activity in that regular and programmed births were achieved.

Absorbable Implants↗
PubMed2003

European Concerted Action on Anticoagulation (ECAA): an assessment of a method for ISI calibration of two whole blood point-of-care PT monitor systems based on lyophilized plasmas using whole blood equivalent PT.

Previously, the attempt to simplify the International Sensitivity Index (ISI) calibration of the CoaguChek Mini whole blood point-of-care test prothrombin time (PT) monitor system was successful using lyophilized plasmas from coumarin-treated patients but not with lyophilized artificially depleted plasmas. With the TAS PT-NC monitor system, both types of plasma failed to provide reliable calibrations. The present study assesses a procedure for the ISI calibration of a TAS PT-NC and CoaguChek Mini whole blood point-of-care test PT monitor systems using lyophilized plasmas. Using lyophilized artificially depleted and coumarin plasma calibrations, we have evaluated a correction for the monitor displayed PT. This was based on a 'line of equivalence' derived from the relationship between whole blood and fresh plasma PT with both types of monitor system. With the TAS PT-NC, the use of this 'line of equivalence' resulted in reliable ISI with both lyophilized coumarin and artificially depleted plasmas. There was no significant difference between mean monitor and mean reference International Normalized Ratio (INR) with the artificially depleted plasmas. With the lyophilized coumarin plasma calibrations there was only a small INR difference. Correction with the 'line of equivalence' therefore facilitates calibration of the TAS PT-NC with lyophilized plasmas. With the CoaguChek Mini, the correction based on the 'line of equivalence' did not improve results but was not required with this system.

Blood Preservation↗
PubMed2003

Oral anticoagulant monitoring by laboratory or near-patient testing: what a clinician should be aware of.

Prothrombin time (PT) is the primary laboratory test for monitoring oral anticoagulant treatment but is influenced by preanalytical conditions and analytical variables, that is, thromboplastin reagents and instrumentation. Standardization and normalization of test results is mandatory. PT results should be transformed to International Normalized Ratio (INR) by calibration of the reagent/instrument system with International Reference standards according to World Health Organization guidelines. However, there is still uncertainty in the INR that is caused in part by calibration errors and in part by interaction between the PT reagent and various factors in the patient's specimen. These problems are highlighted in INR measurements performed with whole blood coagulation monitors. Each center should maintain an appropriate scheme of internal and external quality control for the laboratory INR measurement as well as the individual point-of-care coagulation monitors used by the center and patients for self-testing.

Administration, Oral↗
PubMed2003

European Concerted Action on Anticoagulation (ECAA). An assessment of lyophilised plasmas for ISI calibration of CoaguChek and TAS whole blood prothrombin time monitors.

AIMS: The recommended method for the international sensitivity index (ISI) calibration of whole blood point of care testing (POCT) prothrombin time (PT) systems was originally described by Tripodi et al in 1993 but is too complex and demanding. The present European Concerted Action on Anticoagulation (ECAA) study aimed to assess the reliability of simpler ISI calibration using lyophilised plasma samples. METHODS: ISI calibrations using three different types of ECAA lyophilised plasma samples (artificially depleted, individual, and pooled coumarin) were compared with whole blood calibrations on CoaguChek Mini and TAS PT-NC POCT monitors at 10 centres. RESULTS: With CoaguChek Mini systems, lyophilised coumarin plasma samples (both single donation and pooled) gave ISI and international normalised ratio (INR) values comparable to whole blood. With artificially depleted plasma, ISI and INR values were too high. With TAS PT-NC systems, all three types of lyophilised plasma samples gave inaccurate ISI and unreliable INR results, similar to previous ECAA findings with fresh plasma calibrations. CONCLUSIONS: With CoaguChek Mini systems, ISI calibration can be simplified by the use of ECAA lyophilised plasma samples from coumarin treated patients. Further study is needed to devise a simpler calibration method for the TAS PT-NC system.

Adult↗
PubMed2003

Pharmacological action and therapeutic effects of glutathione on hypokinetic spermatozoa for enzymatic-dependent pathologies and correlated genetic aspects.

In this study, the pharmacologic substance reduced glutathione (GSH) was used in men with hypofertility problems linked to varicocele, in bulls with spermatozoa hypomobility due to varicocele, and in rabbits with dispermy caused by cryptorchidism. An efficacious therapeutic effect of increased motility of the spermatozoa was seen in subjects who were submitted to appropriate doses of glutathione I.M. GSH also showed some neutralizing effect on the catabolytes produced during spontaneous or induced peroxidation processes of the unsaturated lipids contained in the membranes of male germinal cells. The genetic aspects of the involved enzymes were also evaluated and the research was extended in vitro by incubating samples of spermatozoa with arachidonic acid homogenates, L-tryptophan, hematein, and with an addition of glutathione. The results showed that polynsaturated fatty acid metabolic substances (PUFA) play an important role in the acrosomal reaction of spermatozoa and that GSH has a determining role in increasing the motility of spermatozoa with consequent improved fertilization. The spermatozoa of bulls provided us with a valid model to study for the morphostructural, biochemical and pharmacological analyses of human spermatozoa.

Animals↗
PubMed2002

European Concerted Action on Anticoagulation (ECAA). Minimum number of centres for reliable International Sensitivity Index calibration of CoaguChek and TAS point-of-care whole blood monitors.

INTRODUCTION: Prothrombin time (PT) test systems require multicentre calibration for reliable International Sensitivity Index (ISI). Multicentre calibration of CoaguChek Mini and TAS PT-NC point-of-care test (POCT) systems is less precise than conventional PT testing. The aim of the present study was to determine the number of centres required to give reliable ISI and International Normalised Ratio (INR) with these two POCT whole blood PT monitors. MATERIALS AND METHODS: A simulation study, based on results of a 10-centre calibration exercise, was performed to assess reliability of ISI and INR when the number of centres was reduced from 10 to 2. RESULTS AND CONCLUSIONS: With both systems, the range of ISI and INR deviation increased as the number of centres was reduced. For the CoaguChek Mini, at least five centres were needed for satisfactory INR deviation in 95% of calibrations. With the TAS PT-NC, three centres gave satisfactory INR at this level. The number of centres required for multicentre calibration of these two POCT PT systems is greater than the two proposed by World Health Organisation (WHO) Guidelines for conventional PT testing.

Calibration↗