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Biomedical subjects

A Bo

Publications and source records attributed to A Bo.

At least 19 recordsLinked to original sources
PubMed2001

Double plateletpheresis (DPA) and tailored RBC collection with the Excel-Pro: preliminary results.

The Dideco Excel-Pro is frequently used for double plateletpheresis (DPA) when the platelet precount exceeds 280 x 10(3)/l. Platelets are collected as "dry platelets" and the resuspension solution is added when the procedure is over. Even when DPA is carried out the product volume prior to resuspension may be as low as 60 ml. As a result, a third product may be collected along with platelets. Our priority is to collect RBCs and, depending on the donor's BW, tailored RBC collections are carried out. This means that from 400 to 480 ml of PRBC (70% hct) are collected from donors whose BW exceeds 75 kg. The results of the last 27 DPA/tailored PRBC collections are: Donors gender and BW (kg), 19M/8F: 88.4 +/- 7.3 Hemoglobin (g/dl): 15.4 +/- 1.3 Platelet precount (x 10(3)/microl): 308 +/- 45 Volume of blood processed (1): 5.5 Procedure time (min): 81 +/- 3 Platelet yield (x 10(11)): 6.8 +/- 0.6 Avg Hemoglobin content of PBRC (g): 102.6 +/- 12.3 WBC contamination of the platelets: 6.8 +/ -10(5).

Blood Component Removal↗
PubMed2001

The MCS + revision A2 for highly efficient PBSC collection.

Autologous PBSC transplantation is an integral component of the management of hemato-oncology patients. In order to reduce the number of sessions needed to collect the desired number of repopulating cells there has been significant research activity in developing progressively more and more effective technologies and techniques. Recently our group has been involved in the rejuvenation of the MCS + apparatus for both platelet and PBSC collection. The so called "version A2 protocol" is aimed at collecting PBSC in a very efficient way. This protocol is characterized by high blood flow rates both in the collection and reinfusion (80 ml/min) recirculation (56 ml/min) and collection phases (30 ml/min). Only one recirculation is carried out every 5 cycles and only from 5 to 7 are carried out for a single procedure. Twenty-seven collections were carried out of which 25 were evaluable in terms of PBSC efficiency. These averaged 68.8% in an average procedure time of 3.5-5 h for processing an average of 7,052 ml of blood. The RBC contamination was reduced to approximately 5.02 g of hemoglobin and the average volume of the product to 177 ml. If these results are confirmed, the gap between CFC and DFC PBSC is progressively closing.

Adult↗
PubMed2001

Cascade filtration (CF) with the Haemonetics MCS+: a new technical adaptation.

CF was introduced in clinical medicine in 1980. Up to now, exclusively two-vein procedures have been carried out with some limitations to expansion of this technique. In this report we describe the very first application of single-needle CF carried out with Haemonetics MCS + apparatus. Twenty procedures were completed without any untoward effect in patients suffering from TTP, post-hepatitic cryoblobulinemia, familial hypercholesterolemia and acute Guillan-Barrè Syndrome. From 1 to 4 sessions were carried out per patient with the expected laboratory and clinical results. The only limit is the procedure time that averages 231 +/- 48 min., approximately 40% longer than two needle procedures.

Cryoglobulinemia↗
PubMed2000

PCR testing for HCV in anti-HCV negative blood donors involved in the so called HCV +ve post-transfusion hepatitis.

UNLABELLED: Although it is infrequent, post-transfusion HCV infection may occur if the donors blood is collected in the window period between exposure and anti-HCV detectability by ELISA testing. STUDY DESIGN: In these last years, despite of routine application of anti-HCV testing, our blood transfusion center has been involved in 53 cases of alleged post-transfusion HCV hepatitis and look-back programs were set up with the goal of finding out the donors possibly involved in viral transmission. Most of these patients were hematological cases with multiple transfusions given because of aplastic anemia (3 cases), leukemia with or without bone marrow transplantation (5/4 cases) but necessitating long-term platelet support, leukemia and solid cancer patients undergoing autologous PBSC transplantation (3/4 cases) and TTP (2 cases). Only 32 patients were of the simple medical or surgical type, 9 transfused because of cardiac or vascular surgery, 8 because of spine surgery, 5 for different diseases and 5 for different types of cancer surgery. Donor's infectivity was determined by ELISA anti-HCV testing, by recombinant immunoblotting assay, and by nucleic acid testing. RESULTS AND CONCLUSION: No donors out of 267 traced of a total of 359 involved was found with anti-HCV seroconversion, or positive on PCR testing. This suggests that the responsibility for HCV transmission can only hypothetically be related to blood or blood components and that other transmission routes should be found out.

Blood Donors↗
PubMed1999

Cascade filtration for TTP: an effective alternative to plasma exchange with cryodepleted plasma.

TTP remains enigmatic both in terms of etiology and management. The most recent approach is aggressive plasma exchange (PE) employing cryopoor plasma for replacement, based on the pathogenetic relevance given to exceedingly large Von Willebrand (VWF) multimers in the determination of the syndrome with normalization during remission. PE with fresh frozen plasma (FFP) is better than FFP infusion as shown by a recent Canadian study, supporting the theory that to treat TTP an offending circulating agent needs to be removed from the patient's plasma in contrast to the hypothesis that a missing factor is to be given along with FFP. A more recent hypothesis is supported by the results of studies published by the end of 1998 [Moake J, Chintagumpala M, Turner N et al. Blood 1994;84:490-97; Moake J, McPherson PD. Am J Med 1989;87: 3-9N] which would show that TTP is mediated by auto-antibodies to VWF-cleaving protease, or is the result of deficiency of the protease ascribed to abnormalities in its production, function or survival. Plasmapheresis without plasma infusion is relatively ineffective perhaps because it does not increase the protease activity. Cascade filtration (CF) is the autologous counterpart of plasmapheresis. It has been used by our group since 1980 to remove from patients plasma macromolecules such as VWF, fibrinogen, LDL and circulatory immune complexes (CIC). After secondary filtration, the autologous plasma has a composition which is very similar to that of allogeneic plasma after cryoprecipitation, a product which used in the management of TTP. Based on this knowledge, in 1994 we began to use CF in the treatment of TTP patients. In the beginning (7 patients) CF was combined with a decreasing number of conventional PEs using allogeneic plasma for substitution. Lately only CF with some plasma supplementation has been used in the last 9 cases. From a clinical point of view our 16 patients achieved remission after a number of treatments (11 +/- 7) that compares sufficiently well with those required by our historical control group of 47 cases (14 +/- 13). Of course the patient's exposure to allogenic plasma was significantly lower for patients in the CF only group (1.4 +/- 1.2 plasma U/session) compared to the PE + CF group (4.4 +/- 2.3 plasma U/session) or for the controls treated by PE only (10.8 +/- 4.6 plasma U/session). There were no deaths in the CF or PE + CF groups and no untoward effect was observed. On the contrary there were 5 deaths (1 on the day of presentation) in the PE group, and 1 HBV and 2 HCV infections as well as 4 severe allergic reactions to plasma proteins (or passive antibody infusion). We conclude that CF is presently the best treatment to offer to patients suffering from sporadic TTP and that CF may contribute to expanding the knowledge of the pathogenetic mechanisms of this uncommon multisystem disorder.

Adult↗
PubMed1999

Nonlinear three-dimensional finite element analysis of newly designed cementless total hip stems.

We designed 2 new types of proximally coated stems (the FMS and FMS-anatomic) based on the endosteal geometry of femora with congenital dislocation or dysplastic hip. The FMS was symmetric while the FMS-anatomic was asymmetric. We compared the proximal fit and fill to the femoral canal, contact stress, relative motion, and load transfer to the femur of 5 stems (FMS, FMS-anatomic, Omnifit, Omniflex, and individual stem) using three-dimensional computer simulation and finite element analysis. The FMS and FMS-anatomic showed a significantly greater fit and fill than conventional stems. The dispersion of the contact stresses and reduction of relative motions in the proximal area were the best in the FMS-anatomic compared to other stems with the exception of the individual stem. In addition, the FMS-anatomic stem transferred most of the load to the proximal femur. Our results suggest that the FMS-anatomic should provide better biomechanical stability at least in the early postoperative period.

Arthroplasty, Replacement, Hip↗
PubMed1999

Multicomponent collection (MCC) with the latest hemapheresis apparatuses.

BACKGROUND: Collection of multiple products including plasma, packed red blood cells (PBRC) and double units of platelets, is increasingly improving donor utilisation and decreasing blood transfusion costs. Total apheresis is the new trend in blood banking and both industry and physicians are progressively expanding their involvement in this field. During 1998, at our hemapheresis unit, we used three new apparatuses for multicomponent collection (MCC). These apparatuses vary in terms of principle, operation and specific capabilities, and thus knowledge of them is essential to match their characteristics with plateletapheresis needs. STUDY DESIGN: We reviewed all MCCs carried out in 1998 with MCS+, Trima and Excel-Pro cell separators. These apparatuses were evaluated in terms of platelet yield, white blood cell (WBC) contamination, efficiency per minute, platelet activation, and PBRC product quality. RESULTS: The three machines are compared in the following table [table in text]. CONCLUSIONS: MCC with the new apparatuses is well accepted by donors and personnel. There are no risks for the donors and, excluding ACD reactions and/or vaso/vagal attacks at the beginning of procedures, no severe reaction was seen. The quality and quantity of platelet products are good. When PRBC or a second platelets unit are collected, the cost of the kit is covered by this double product.

Blood Component Removal↗
PubMed1999

[Clinical practice of spherical allogeneic biological membranous implant in the eye socket].

OBJECTIVE: To investigate the effect of implantation of spherical allogeneic biological material implant after eyeball enucleation. METHODS: A spherical allogeneic biological material implant was implanted in the eye socket after eyeball enucleation in 50 cases including stage I in 48 cases and stage II in 2 cases. RESULTS: After operation, the motility of installed artificial eyes was good in 49 cases, the orbit and eyelids were full in all the cases. In the follow-up of 4 - 24 months (mean, 8 months), the conjunctival wound and muscular tissue were adherent firmly to the biological material, and there were no postoperative infection, no dislocation and shift of the implant. CONCLUSION: The spherical allogeneic biological membranous implant is an ideal material for the implantation in the eye socket after enucleation.

Adolescent↗
PubMed1998

Characterization of the structural and functional changes of hemoglobin in dimethyl sulfoxide by spectroscopic techniques.

Circular dichroism (CD), fourier transform infrared (FTIR), and fluorescence spectroscopy were used to explore the effect of dimethyl sulfoxide (DMSO) on the structure and function of hemoglobin (Hb). The native tertiary structure was disrupted completely when the concentration of DMSO reached 50% (v/v), which was determined by loss of the characteristic Soret CD spectrum. Loss of the native tertiary structure could be mainly caused by breaking the hydrogen bonds, between the heme propionate groups and nearby surface amino acid residues, and by disorganizing the hydrophobic interior of this protein. Upon exposure of Hb to 52% DMSO for ca. 12 h in a D2O medium no significant change in 1652 cm-1 band of the FTIR spectrum was produced, which demonstrated that alpha-helical structure predominated. When the concentration of DMSO increased to 57%: (1) the band at 1652 cm-1 disappeared with the appearance of two new bands located at 1661 and 1648 cm-1; (2) another new band at 1623 cm-1 was attributed to the formation of intermolecular beta-sheet or aggregation, which was the direct consequence of breaking of the polypeptide chain by the competition of S&z.dbnd6;O groups in DMSO with C&z.dbnd6;O groups in amide bonds. Further increasing the DMSO concentration to 80%, the intensity at 1623 cm-1 increased, and the bands at 1684, 1661 and 1648 cm-1 shifted to 1688, 1664 and 1644 cm-1, respectively. These changes showed that the native secondary structure of Hb was lost and led to further aggregation and increase of the content of 'free' amide C&z.dbnd6;O groups. In pure DMSO solvent, the major band at 1664 cm-1 indicated that almost all of both the intermolecular beta-sheet and any residual secondary structure were completely disrupted. The red shift of the fluorescence emission maxima showed that the tryptophan residues were exposed to a greater hydrophilic environment as the DMSO content increased. CO-binding experiment suggested that the biological function of Hb was disrupted seriously even if the content of DMSO was 20%.

Animals↗
PubMed1997

Stress fracture of the femoral component in total knee replacement: a report of 3 cases.

We report 3 cases of stress fracture of the femoral component (small size Whiteside Ortholoc II) in total knee replacements which occurred at 32, 52, and 73 months after operation. The site was at the junction between the medial posterior bevelled surface and the posterior flange. The most likely cause of failure is due to the thinness of the metal at this point.

Aged↗
PubMed1994

Performance assessment of coupled tests: the effects of statistical non-independence.

Limited to two-test associations (series and parallel schemes), the effects of statistical non-independence were studied through a mathematical approach and an experimentally-based evaluation. Both procedures were applied to results for total hormones and free fractions in euthyroid and dysthyroid subjects. Assuming independence, the sensitivity of combined tests was found to increase in parallel coupling, and to decrease, symmetrically, in series coupling, depending critically on the degree of between-test correlation and on the value of single test sensitivity (the opposite modifications obviously occur for specificity). A more complicated situation resulted for the predictive value of test associations, where a prediction based on a mathematical model was found not to be generally valid; in this case, calculations using the correct values of conditional probabilities of coupled tests seemingly remain the safest procedure.

Algorithms↗
PubMed1993

DECIDE: a software for computer-assisted evaluation of diagnostic test performance.

The evaluation of the performance of clinical tests is a complex problem involving different steps and many statistical tools, not always structured in an organic and rational system. This paper presents a software which provides an organic system of statistical tools helping evaluation of clinical test performance. The program allows (a) the building and the organization of a working database, (b) the selection of the minimal set of tests with the maximum information content, (c) the search of the model best fitting the distribution of the test values, (d) the selection of optimal diagnostic cut-off value of the test for every positive/negative situation, (e) the evaluation of performance of the combinations of correlated and uncorrelated tests. The uncertainty associated with all the variables involved is evaluated. The program works in a MS-DOS environment with EGA or higher performing graphic card.

Clinical Laboratory Techniques↗
PubMed1992

The imprecision profile in immunoassay. A study using a resampling technique.

A resampling ('bootstrap') technique was applied to assess the reliability of the calculated imprecision profile (IP), as obtained from the dose/response curve and the response/error relationship (RER) using the cumulative data relative to two assays, i.e. a T4 radioimmunoassay (RIA) and a TSH immunofluorometric assay (IFMA), both run in duplicate. Mean values and the related uncertainty of the estimated dose errors were compared for different RER fitting conditions and different sizes of the duplicate response sets. The following observations were made: (a) compared to the maximum-likelihood procedure, the least-square fit proved to be unsuitable for estimating the parameters in the general RER equation variance(R) = aRb (where R indicates the response), (b) the simplifying assumption of a within-method constancy of the exponent in the RER equation, while acceptable for the T4 RIA, did not hold in the case of the TSH IFMA implying a much wider response range, (c) for both assays, response sets of ca. 100 duplicates were apparently compatible with an acceptable definition of the IP (+/- 10 to +/- 20% uncertainty).

Bias↗
PubMed1991

Statistical tools in the clinical laboratory.

Method evaluation, control of data and transformation of laboratory results into diagnoses all involve a decision step. A survey of the statistical tools available to organize the information and check the congruity of decision making is provided is focused on: (a) the use of classical statistical tools (including computer based simulation and replication techniques) which enable theoretical distributions to be obtained and their optimal limits to be defined for classification purposes; (b) the analysis of multivariate distributions, which evidences the relationships among the variables involved, whatever they might be: e.g. results obtained on the same specimens with different methods (in test evaluation), different laboratory data related to the same pathophysiological situations (in making diagnoses), etc. As for the latter, the most common techniques of statistical analysis of data (discriminant and cluster analysis, principal components analysis) are also illustrated by general examples.

Analysis of Variance↗
PubMed1987

[The Chernobyl accident. Evaluation of the doses absorbed by the thyroid gland in children of a mountain community from the measurement of I131 retained activity].

I131 thyroid uptake after the Chernobyl's accident was sampled in a Val Pellice school. Children were grouped according to sex, age and area of residence. The procedure used in collecting data and calculating the transformation coefficients from activity counts by computer simulation is analysed, as are the errors and sensitivity of the method. The activities were then converted into doses using an intake model. The dose levels identified are lower than the estimates based on the measurement of environmental matrices. Statistical analysis revealed certain subgroups with significantly different levels of absorption: particularly groups accustomed to a different diet or living in particular areas.

Accidents↗
PubMedDate not supplied

Assessment of response/error relationship and imprecision profile in immunoassay using computer simulation procedures.

Simulation procedures were applied to assess the response/error relationship (RER) and the imprecision profile (IP) for two model assays, a T4 RIA and a TSH IFMA both using duplicate samples. In order to define the reference functions, the mean data obtained in 10 successive experiments for dose/response curve (DR), RER and IP were employed. The following conclusions emerged from the study: (a) run sizes of ca. 100 duplicates can acceptably describe within-assay IPs, irrespective of the data distribution through the dose range; (b) the contribution of DR fitting error to the total variability of estimate can be disregarded in the case of small series but not for the larger ones; (c) the variability components related to the response error can be efficiently controlled by applying criteria based on RER parameters.

Computer Simulation↗