Mapping Protein-Protein Interactions at Birth: Single-Particle Cryo-EM Analysis of a Ribosome-Nascent Globin Complex

Interactions between ribosome-bound nascent chains (RNCs) and ribosomal components are critical to elucidate the mechanism of cotranslational protein folding. Nascent protein-ribosome contacts within the ribosomal exit tunnel were previously assessed mostly in the presence of C-terminal stalling sequences, yet little is known about contacts taking place in the absence of these strongly interacting motifs. Further, there is nearly no information about ribosomal proteins (r-proteins) interacting with nascent chains within the outer surface of the ribosome. Here, we combine chemical cross-linking, single-particle cryo-EM, and fluorescence anisotropy decays to determine the structural features of ribosome-bound apomyoglobin (apoMb). Within the ribosomal exit tunnel core, interactions are similar to those identified in previous reports. However, once the RNC enters the tunnel vestibule, it becomes more dynamic and interacts with ribosomal RNA (rRNA) and the L23 r-protein. Remarkably, on the outer surface of the ribosome, RNCs interact mainly with a highly conserved nonpolar patch of the L23 r-protein. RNCs also comprise a compact and dynamic N-terminal region lacking contact with the ribosome. In all, apoMb traverses the ribosome and interacts with it via its C-terminal region, while N-terminal residues sample conformational space and form a compact subdomain before the entire nascent protein sequence departs from the ribosome.

[Evaluation of the training of clinical pharmacy residents in prescription analysis using an ergonomic approach]

OBJECTIVES

To perform an ergonomic intervention using the methodology of the analysis of the activity of the training process of clinical pharmacy residents in the analysis of prescriptions.

METHODS

The evaluation was carried out over two semesters: from May to October 2016 (first study) and from November 2016 to April 2017 (second study). The interviews and observations were conducted by an ergonomist who is an expert in this type of evaluation. The first study was based on observations of the training process and interviews at different time. The second study allowed to support pharmacists and evaluate the changes following the recommendations of the previous study.

RESULTS

A total of 6 and 9 residents participated in the first and second study, respectively. During the first study, 6 difficulties were raised which allowed implementation decisions. Feedback from residents on the training process was generally positive for the first part of the training but negative for the last part. The average number of fears expressed by the residents was higher at the beginning (2.9 fears) than at the end (1 fear).

CONCLUSIONS

The training process has been adapted to the expectations and feelings of the residents. Follow-up at the beginning and throughout the internship was essential. The next stage of this work will be to evaluate the contribution of the dashboards for monitoring clinical pharmacy skills in the new degree for hospital pharmacy.

Analysis of plasticizers in PVC medical devices: Performance comparison of eight analytical methods

A wide variety of medical devices (MDs) used in hospitals are made of flexible plasticized polyvinylchloride (PVC). Different plasticizers are present in variable amounts in the PVC matrix of the devices and can leach out into the infused solutions and may enter into contact with the patients. The ARMED¹ project aims to assess the migration of these plasticizers from medical devices and therefore the level of exposure in patients. For the first task of the project, eight methods were developed to directly detect and quantify the plasticizers in the PVC matrix of the MDs. We compared the overall performances of the analytical methods using standardized and validated criteria in order to provide the scientific community with the guidance and the technical specifications of each method for the intended application. We have shown that routine rapid screening could be performed directly on the MDs using the FTIR technique, with cost-effective analyses. LC techniques may also be used, but with limits and only with individual quantification of the main plasticizers expected in the PVC matrix. GC techniques, especially GC-MS, are both more specific and more sensitive than other techniques. NMR is a robust and specific technique to precisely discriminate all plasticizers in a MD but is limited by its cost and its low ability to detect and quantify plasticizer contamination, e.g. by DEHP. All these results have been confirmed by a real test, called the " blind test " carried out on 10 MD samples.

Quality assessment of seven types of fresh-frozen plasma leucoreduced by specific plasma filtration

BACKGROUND AND OBJECTIVES

A study was undertaken to determine plasma quality after specific filtration.

MATERIALS AND METHODS

Seven types of plasma were tested, after filtration of plasma from filtered or non-filtered whole blood. Leucocyte counting was carried out after a 30-fold concentration of the sample. Twenty-nine parameters (including coagulation testing, proteins, coagulation factors and activation markers) were measured before and after filtration, and after 6 months of storage.

RESULTS

After specific plasma filtration, the average residual leucocyte counts were less than 2250/l. In spite of small statistically significant changes in proteins, coagulation factors and complement activation, this study showed that plasma filtration did not alter plasma quality. After 6 months of storage at -30 degrees C, factor VIII recovery varied between 91 and 109%. Haemostasis parameters and activation markers remained within the normal range.

CONCLUSIONS

Specific plasma filtration reduced the leucocyte number to < 104 leucocytes/l. The quality of plasma was not altered by the additional step of specific plasma filtration.

Soluble Fas is a marker of coronary artery disease in patients with end-stage renal disease

Coronary artery disease (CAD) is the leading cause of death in patients with end-stage renal disease (ESRD). Recent evidence suggests that the expression of Fas, a molecule implicated in the initiation of apoptosis in various cell types, is increased at sites of atherosclerotic plaques. However, the significance of plasma levels of the soluble form of Fas (sFas) and its ligand (sFas-L) as markers of atherosclerosis has yet to be defined. The present report is a cross-sectional analysis of baseline data from an ongoing prospective study designed to evaluate the role of sFas and sFas-L as markers of CAD in ESRD. We evaluated the association between plasma levels of sFas and sFas-L and evidence of CAD in a cohort of 107 chronic hemodialysis patients. Plasma levels of sFas were significantly greater (P = 0.04) among subjects with (n = 64) than without evidence of CAD (n = 43). Plasma levels of sFas-L were similar in both groups. Using multivariate analysis, sFas level was found to be independently associated with CAD (P = 0.01) after adjustment for classic risk factors for CAD (hyperlipidemia, diabetes, hypertension, and smoking), markers of inflammation (C-reactive protein [CRP], intercellular adhesion molecule 1), and other confounders. An increase of one quintile in plasma concentration of sFas was associated with an odds ratio for CAD of 1.64 (95% confidence interval, 1.11 to 2.41). Models that incorporated sFas were significantly better at identifying patients with CAD than models limited to classic risk factors for atherosclerosis, alone (P = 0.008) or in combination with CRP levels (P = 0.006). In summary, increased plasma levels of sFas are associated with CAD in stable patients with ESRD. These results suggest that sFas may represent a novel and independent marker of CAD.

Plateletpheresis concentrates produced with the COMTEC cell separator: the French experience

The latest generation of cell separators such as Trima (Gambro), Amicus (Baxter) and AS-TEC 204 (Fresenius), allow the collection of leucocyte-reduced platelet concentrates without secondary filtration. Fresenius has recently developed the COMTEC cell separator whose performance has been evaluated by several teams in France. This new cell separator is an improved version of the Fresenius AS-TEC 204 cell separator, designed to allow more efficient platelet collections. This study reports on the experience of six French teams (from Bordeaux, Clermont-Ferrand, Creteil, Dijon, Lille and Nancy) who obtained 696 leucocyte-reduced plateletpheresis concentrates in the course of collection using the new Fresenius COMTEC cell separator. All healthy volunteer donors fulfilled French selection criteria for platelet apheresis. Donors were eligible if they had suitable venous accesses, if their bodyweight was *50 kg and if their pre-apheresis platelet count was >150 x 10(9) l(-1). Between 4606 and 5229 ml of blood were processed. The mean volume of the platelet concentrates was between 439 and 493 ml (mean 460 +/- 63 ml). The platelet yield was of the order of 5.18 +/- 1.02 x 10(11) with only one platelet concentrate below the norm of 2 x 10(11) platelets (0.91 x 10(11)). No plausible explanation for this was found. The residual leucocyte levels conform to current norms. The platelet concentrates contained less than 1 x 10(6) leucocytes per concentrate (mean 0.233 +/- 0.150 x 10(6) leucocytes) in more than 97% of the components produced with >95% statistical confidence. The efficacy of the cell separator (52.44 +/- 7.35%) is comparable to that of other separators. The Fresenius COMTEC cell separator makes it possible to obtain leucocyte-reduced platelet concentrates which comply with current standards both in terms of platelet content and residual leucocyte level.

Universal leukoreduction of cellular and plasma components: process control and performance of the leukoreduction process

Many countries in Europe and over the world are currently or will be concerned in the near future, by the implementation of universal leukoreduction (ULR) for red blood cells (RBC), platelets (PT) and now also for plasma. Recommended by several advisory committees, this decision to implement ULR must be considered as a recognition of the benefit of early leukocyte removal, and also as a precautionary measure to increase blood safety. The leukodepletion technology for RBC, PT and plasma has become increasingly more elaborated and integrated in the collection or in the component preparation process. To reach this aim and to assure that the end-products meet local specifications (1 or 5 x 10(6) residual leukocytes), a process control and validation program for leukoreduction has been described in the specific guidelines. Tested on a wide scale by a group of centers, flow cytometry is emerging as reference method for residual leukocyte enumeration. Validation protocols (linearity, precision, accuracy) have been defined in numerous national or international studies (PSL and BEST Working Party). The sensitivity of the method is greatly improved by concentration of the sample, with a detection limit equivalent to 10 cells/mL for RBC or PT, and 0.5 cells/mL for plasma. Furthermore, monitoring of the performance of the leukoreduction process includes a quality control program based on a general statistical model with a parametric or non parametric approach, sampling plan, ongoing control, process capability assessment, confidence limit, detection of failure, and estimation of the non conforming units rate.

A new symmetry-based scoring method for posture assessment: evaluation of the effect of insoles with mineral derivatives

BACKGROUND

There is a need for a validated rapid procedure for the evaluation of posture, defined as lateral balance/imbalance at the pelvic, shoulder, and neck levels. This would enable clinicians to determine the importance of symmetry in the pathophysiology of musculoskeletal disorders and to assess the efficacy of devices and treatments claiming to normalize or improve posture. In this investigation, the efficacy of such a device, a set of insoles with a hypothesized proprioceptive-like action, was evaluated through use of the described procedure.

OBJECTIVES

To develop a new scoring system to evaluate body posture on the basis of symmetry and to use this scoring system to investigate the efficacy of insoles containing a combination of mineral derivatives designed to balance posture through a neurophysiological effect.

METHODS

The posture score was based on the evaluation of 4 postural parameters: pelvic and shoulder lateral balance/imbalance, static shoulder rotation, and amplitude of head rotation. In the placebo-controlled study, 32 patients were tested in a double-blind fashion, either with placebo insoles or with insoles containing mineral derivatives. The same study was repeated in unblind conditions in 137 patients selected from 2 chiropractic clinics in an open-label protocol.

STUDY DESIGNS

A crossover placebo-controlled, double-blind study and a multicenter, large-scale, open-label study in patients selected from chiropractic clinics.

RESULTS

A basal postural evaluation in 137 patients revealed that no patient had a perfect symmetry-ie, a perfectly or nearly perfectly balanced posture. The insoles with mineral derivatives induced a highly significant and similar improvement in the postural score in both the crossover double-blind study (32 patients; 56.7% improvement) and the open-label study (137 patients; 60.7% improvement, P < 0.001).

CONCLUSIONS

All patients tested and selected in chiropractic clinics exhibited asymmetries and postural imbalances according to the newly developed scoring method, and this method was successful in assessing the efficacy of insoles exerting a profound and immediate postural effect through a hypothesized neurophysiological mode of action.

[Quality control of labile blood products. Why and howto properly take a specimen? Labile Blood Products Group of the French Blood Transfusion Society]

This article reviews the various techniques of sampling used for the quality control of blood cell products. The importance of this stage for the validity of quality control results is emphasized. Three sampling methods, i.e., stripping, the sterile connection of sampling bag and the destructive method, are described in the form of operating modes and analyzed according to their advantages and drawbacks. The results of a comparative study carried out by the working group 'Blood Cell Products' of the French Society of Blood Transfusion are presented, showing that each method is valid and permits one to obtain a representative sample of the product to be controlled. Thus the diversity of the sampling methods allows us to select the one most adapted to the product to be controlled and to the analyses to be carried out afterward.

[Surveillance of biocontamination of the environment of labile blood products: its role in a quality assurance program]

As part of a quality assurance approach aiming at reducing the risk of bacterial contamination of labile blood components (BC), their environment was submitted to a twofold quality control. A yearly control was carried out by the University Hospital Laboratory of Hygiene (UH-LH). Another control was regularly implemented by our Quality Control Laboratory. In accordance with this quality system, we focused our attention on decontamination procedures, control targets and the definition of an acceptable threshold. The analysis of results over 1 year showed that they can be considered as satisfactory when less than 40 CFU/100 cm2 are found. Quality sheets were developed, aimed at motivating our staff, adapting the decontamination procedures and initiating corrective measures. This quality programme allowed us to develop close collaboration links with the UH-LH and to play a role in the prevention of hospital-acquired infections.

Modulation of HLA-DR and CD1a expression on human cornea with low-dose UVB irradiation

PURPOSE

To evaluate the effects of low-dose UVB irradiation of HLA and CD1a expression and the toxic effects of UVB on human corneas.

METHODS

24 pairs of human corneas from 24 donors were studied. One cornea from each pair was randomly irradiated with UVB (100 mJ/cm2) after enucleation. All corneas were then organ-cultured for 2, 7, 14 or 21 days. Endothelium was studied after enucleation and organ culture. Following preservation, corneas were evaluated by means of light microscopy, morphometry and TEM. HLA and CD1a staining was performed using an immuno-alkaline-phosphatase technique.

RESULTS

Endothelial cell loss during organ culture averaged 9.1% in the UVB group and 9.2% in the control group (NS). The number of rosette and reformation figures (p = 0.004) and the coefficient of variation (p = 0.014) were higher in the control group. Epithelial sloughing was more accentuated in the UVB group. We observed the same moderate ultrastructural injuries in both groups. In the epithelium, the average number of HLA-DR+ cells per field was 0.12 in the UVB group and 0.42 in the control group (p = 0.035). In the stroma, these figures were respectively 1.04 and 1.34 (p = 0.026). In the epithelium, the average number of CD1a + cells was respectively 0. 025 and 0.078 (p = 0.019). In the preservation mediums, the average percentage of CD1a + cells was 0.07% in the UVB group and 0.27% in the control group (p = 0.014).

CONCLUSIONS

Low-dose UVB (100 mJ/cm2) decreases HLA-DR and CD1a expression of organ-cultured human corneas and induces moderate corneal injuries. Low-dose UVB might be useful for preventing allograft rejection.

Multicenter evaluation of the 3% paraformaldehyde method for white cell counting in leukocyte-reduced red blood cells. BEST (Biomedical Excellence for Safer Transfusion) Working Party of the International Society of Blood Transfusion

BACKGROUND/AIM

The 3% paraformaldehyde (PFA) method is a simple technique for counting residual white blood cells (WBC) in leukocyte-depleted red blood cells (RBC). Preliminary data suggested that its sensitivity is at least equal to PCR and flow cytometry. We report the results of a multicenter study conducted by the BEST Working Party to determine precision and accuracy of the 3% PFA method.

STUDY DESIGN

In the 7 participating laboratories, 5 sets of samples containing nominal concentrations of 200, 100, 50, and 10 WBC/ml were prepared by diluting whole blood into 'WBC-free' RBC. Ten milliliters of each sample were processed using the 3% PFA method, which is based on erythrocyte lysis and WBC concentration into 5% of the original sample volume; a Nageotte chamber is used to count concentrated WBC.

RESULTS

The precision of the technique varied according to the nominal concentration, ranging from a CV of 12% at 200 WBC/ml to 57% at 10 WBC/ml. The technique measured fewer than the nominal WBC concentrations (mean of all laboratories, -12.4%); underestimation was probably due to cell loss during sample manipulation. Overall accuracy was however acceptable, because statistical considerations establish that the actual WBC concentration would unlikely exceed 2 times the estimated count.

CONCLUSIONS

The 3% PFA method is suitable for the enumeration of residual WBC at concentrations > or = 50/ml. It represents a useful tool for evaluation of high performance filters by reference laboratories.

[Quality of platelet products: current methods of in vitro assessment]

Efficiency of platelet transfusion is closely related to the quality of the preparation and also to the optimization of storage conditions at 20 degrees C. During this last years, processes for obtaining platelet suspensions became different (platelet rich plasma platelet, pooled or single buffy coat platelet, apheresis platelet), process for purification were developed (filtration, gamma or UV-irradiation, synthetic media for storage, virus inactivation), duration of storage was extended to 5 or 7 days and clinical applications were intensified. According to this advance, noted in some European countries, multicenter consensus on methods of quality control must be defined by different study groups. In the recent past, many publications have described a lot of in vitro tests for estimating functions, morphology, metabolic activity, lysis and activation of platelets. Current available methods for routine quality control or for development of new procedures, such as pH measurement inspection of swirling, percent of discoid shape, mean platelet volume, hypotonic shock response or total ATP level should be considered, in accordance with the in vivo viability.

[Current data on the counting of weak leukocyte concentrations in labile blood products]

The precise measurement of low numbers of leukocyte below 0.1 WBC/microliter in filtered red cell or platelet suspensions meet both aims: to check the compliance with previously determined requirements and to evaluate the performances of novel filtering material (5 log depletion or more), justified by more and more important clinical use. The reliability of results, obtained with the chosen method, is ensured by applying of validation protocol, including training of technologist, assessment of the analytical range and the detection limit, assessment of precision and accuracy. The flow cytometry (FC) and Nageotte Chamber (NC) method are the both techniques which are currently used in routine Quality Control (QC) and validated by multicenter studies. Recent developments are made for increasing the sensibility of these counting methods, thanks to higher concentration or volume of the sample to be analysed. Among the experimental techniques, requiring more advances before implementing in QC program, quantitative PCR must become essential as reference method for evaluating the efficiency of filtration, in the future.

[Assessment of filtration performance]

The technique of filtration which has constantly been improved over past years makes it possible to obtain highly pure blood products (the rate of leukocyte depletion can reach 3 to 5 log). Several study groups (BEST, PSL) and international committees of experts have defined a number of standards with which leukocyte depleted blood products must comply. Assessment of filtration procedures is thus made necessary, it applies to the different steps of the filtration procedure: preparation techniques of red cell or platelet suspension, priming and rinsing of the filter. Likewise a number of parameters have to be checked: filtration time, temperature, age of suspensions. Moreover quality control procedures must be implemented, using adapted and validated measuring methods (Nageotte hemacytometer, for instance). The parameters to be monitored include the number of residual leukocytes, (mean value: 1 x 10(6), i.e. about 4 WBCs/microliters), and the rate of hemoglobin or platelet recovery. Any new filtering equipment or material must satisfy strict requirements and standards including clinically acceptable limits as part of the same quality approach. Validation, in this case, consists in determining the maximal leukocyte content which the filter can absorb (capacity) and the average rate of leukocyte removal (efficacy). The constant monitoring of filtration performance contributes to improving the quality of red blood cell or platelet suspensions and thus meet clinicians' requirements for their patients.

First results obtained in France with the latest model of the Fresenius cell separator: AS 104

In Besançon, we carried out 40 plateletphereses with the latest model of the Fresenius cell separator AS 104 to check this new system against the new generation of cell separators, according to the following criteria: less than 2x10 6 leukocytes (before filtration) and more than 5x10 11 platelets. The results show that platelet concentrates contained 5.04+/-0.88x10 11 platelets in a total volume of 435+/-113 mL. The mean platelet recovery was 40.95+/-4.86% (from 31.7 to 51.6). The leukocyte content was 2.28+/-5.48x10 6 and the red blood cell contamination was 3.48+/-2.38x10 8. The quality of the platelets was very satisfactory. There was no problem with donor biocompatibility or procedure safety, few adverse donor reactions (0.6%) and good therapeutic efficiency of platelet concentrates.

Validation of a simple method to count very low white cell concentrations in filtered red cells or platelets

The increased performance of white cell (WBC) filters makes it difficult to count precisely the number of residual WBCs. Concentrations as low as 0.01 WBC per microL cannot be determined with electronic cell counters, conventional hemocytometers, or the flow cytometric techniques currently being used. This article describes a simple, manual method using a Nageotte hemocytometer with a large-volume chamber (50 microL) to count the number of WBCs contained in red cell (RBC) suspensions (preparations A, B, and C) and in platelet suspensions (preparation D) diluted 1 in 10 pure, or concentrated two fold. To validate the method, several reference ranges, prepared by successively adding mononuclear cells to a suspension of pure RBCs or platelets, were used. Among the different series, validation ranges varied from 0.2 to 12 to 0.01 to 0.5 WBCs per microL and correlation coefficients ranged from 0.929 to 0.996. To determine the limit of accurate detection, accuracy tests (n = 160) were carried out by two experienced operators on samples with WBC concentrations of about 5, 10, and 120 times the concentration at the theoretical limit of detection (1 WBC/chamber). No significant difference was observed in the various types of preparations (A, B, C, D) in the tests performed by the two operators. However, intra-assay coefficients of variation were 18, 9.5, and 2.2 percent, respectively, at WBC concentrations of 5, 10, and 120 times that at the theoretical limit of detection. These observations show that a limit of accurate detection (10%) seems to be reached when 10 cells are observed in a Nageotte hemocytometer.(ABSTRACT TRUNCATED AT 250 WORDS)

A multicenter study on the efficiency of white cell reduction by filtration of red cells

To evaluate accurately the current performance of filtration, the French Produits Sanguins Labiles study group, composed of 21 transfusion teams, conducted a large-scale 6-month study involving over 1400 filtrations and 3000 controls. Some 745 standard red cell concentrates (RBC concentrates) and 690 concentrates previously white cell (WBC)-reduced by removal of buffy coat (BC-poor RBC concentrates) were filtered using six commercially available filters: at least 170 results were collected per filter, spread among a minimum of three teams. Prefiltration controls show that the removal (manual and automated) of the buffy coat results in an initial WBC reduction of approximately 63 percent, along with a hemoglobin loss of 4 g (7%). After filtration, residual WBCs were counted in the Nageotte manual counting chamber. The reliability of this counting method, which is simple and adapted to low WBC concentrations, was characterized in this study by a 25-percent coefficient of variation (CV) for a concentration of 2.5 WBCs per microL (i.e, 0.6 x 10(6) WBCs/filtered unit). The analysis of the results shows that, for five of six filters (1 filter was excluded), the postfiltration median value of residual WBCs was 1.1 x 10(6) in filtered RBC concentrates (n = 590), whereas it was 0.34 x 10(6) in filtered BC-poor RBC concentrates (n = 581). The difference is significant (p less than 10(-8), Wilcoxon test). Hemoglobin loss due to filtration varies according to the filter, from 5.7 +/- 2.2 to 17.3 +/- 2.5 g.(ABSTRACT TRUNCATED AT 250 WORDS)

[Multicenter study on the efficacy of leukocyte depletion by filtration of red cells. The Labile Blood Products Group]

To determine the actual efficacy of red cells filtration technique, the "Labile Blood Component Production" french study group, including 21 blood centers, realized a large study on more than 1,400 filtrations and 3,000 controls. 745 units of red cell concentrates (RCC) and 690 units of buffy-coat poor red blood cells (BC PRBC) were filtered through 6 commercialized leukocytes depleting filters: not less than 170 experiments per filter, tested by 3 different blood centers. Pre-filtration controls prove that buffy-coat removal, done manually or with automated equipment, involves a first leukocytes depletion about 63% and an hemoglobin loss equal to 4 g (7%). After filtration, residual leukocytes counts were performed manually in a Nageotte counting chamber. In this study, we evaluated the reliability of this simple method which accurately measures very low leukocytes counts. The variation coefficient was 25% for 2.5 leukocytes/microliter concentration (O.6 x 10(6) per filtered unit). The results, obtained from 1200 evaluated filtrations, confirm that buffy-coat removal obviously improves the filtration performances (residual leukocytes level is lower than 1 x 10(6) per unit for 78% filtered BC PRBC versus 43% filtered RCC). Furthermore, 90% of overall filtered units are containing less than 5 x 10(6) leukocytes.

[Quality control management. Application to the production of unstable blood components]

The quality controls of blood components, realised in Transfusion Centres, are necessary to check the true conformity of products in accordance with official standards. This controls are insufficient to enhance blood components quality. The practical application of the quality management allows us to reach this aim easier. After the quality display, after it efficiency and regulatory measurement and after a quality objectives selection, we consider that the professional training and the data presentation contribute to the necessary confidence for a better quality management. Finally, standardization and automatization of production processes constitute the only ways to improve the real quality, to decrease waste products and, of course, to increase the productivity.

New methods for detection of HLA genes polymorphism useful for associated diseases studies

We have studied in 22 informative families typed for HLA the segregation of DNA restriction fragments obtained with five restriction enzymes and hybridized with one class I and three class II probes. Most of the fragments correlate with serologically defined specificities. Many fragments can be grouped in clusters, whose genetic significance is discussed. The RFLP distribution in patients with insulin-dependent diabetes mellitus, multiple sclerosis or narcolepsy, three diseases known to be associated with some HLA-DR specificities, has been also studied. Many fragments allow to distinguish between patients and HLA-DR matched controls. Hybridization of genomic DNA with synthetic oligomers will refine moreover the understanding of the HLA system polymorphism.

[Controlled centrifugation by a w2dt integrator. Application to blood transfusion]

The centrifugation constitutes a fundamental stage in the blood components preparation as fresh frozen plasma and platelets rich plasma. The measure of the total effect of centrifugation (VT) is achieved with an integrator "w2dt". This parameter characterizes, in an unique way, the preparation procedure of a blood component. The value VT is determined and then sticked on the integrator, which made the rotation stop as soon as the preselected effect of centrifugation is reached. Thanks to this accessory, the authors have analysed the relative importance of the three data: acceleration, constant speed and deceleration, on the total effect of centrifugation. This analysis has induced them to a new approach of the centrifugation. For the authors, the classic notion of rotation time at constant speed, become insufficient. In blood transfusion, several applications are possible. The authors have determined the optimal conditions of platelets rich plasma (yield higher than 80% during a minimum real time) and platelets concentrate preparation with two different centrifuges, Sorvall RC3B and Jouan K 110 SX, equipped with Sorvall Integrator. The reproductibility of the experiments is satisfying when the centrifuged weight is comparatively constant. The standardization of centrifugation technics will be easier when the rotation radius will be included in the calculation of the total effect of centrifugation, thanks to integration.

Human platelets frozen with glycerol in liquid nitrogen: biological and clinical aspects

Platelets were frozen using glycerol (3% in plasma) as a cryoprotective agent, a rapid cooling rate, and liquid nitrogen for storage. The cryopreserved platelets were thawed at 42 C and infused without washing. The results indicate that the quality of the thawed platelets is equivalent to platelets stored for 24 to 48 hours at room temperature. The availability of HLA phenotyped leukocyte poor platelets can reduce the frequency of sensitization to strong antigens and provide clinically effective platelets for alloimmunized patients.

[Treatment of immediate post-operative agitation (author's transl)]

Though organic causes and operative factors can produce post-operative agitation, a background of anxiety, alcoholism, or neurosis plays a major role in its development. Excellent results were obtained with tiapride in 58 patients with post-operative agitated states. Local and general tolerance were both excellent. Furthermore, an association of tiapride-corticoids was effective in treating post-anaesthetic spasm of the glottis.

Application of cell electrophoretic methods (preparative and analytical) in demonstrating the surface heterogeneity of T-lymphocytes in man

The preparative electrophoretic method allows separation of several cell populations, which can be characterized by the usual membrane markers. This qualitative study shows a heterogeneous distribution of the T-lymphocytes from the most rapid to the slowest migration zones. The electrophoretic mobility (E.M.) of each fraction has been studied by analytical electrophoresis, which confirms the heterogeneity of T-cells. The experiments used total blood lymphocytes and rosette-forming cells with sheep red blood cells. The results obtained with the two methods were well correlated. The average migration speed of the separated populations showed a regular variation from one extreme fraction to the other. The E.M. speeds that characterize the main populations are--0.90 micrometer.sec.--1v.--1cm for the B-lymphocytes; for the T-lymphocytes,--1.10 (previously identified as the "low affinity" E-rosette FC),--1.20 and a small population centered around--1.35 (corresponding to active E rosette FC). In the T-lymphocytes separated after E-rosetting, the progresssive variation in the mean E.M. of each fraction is confirmed, as well as the existence of the previous 3 T-cell populations. Further studies have to be done, to show that each separated population does correspond with a functional differentiation.

[Application of free flow preparative methods for the separation of blood cells]

Human blood cells can be separated using an apparatus described by Hanning and co-workers (Model FF4 Desaga Heidelberg). The method of free flow preparative electrophoresis uses a specific property of blood cells when subjected to an electric field: their electrophoretic mobility. Three regions of migration can be defined: --a high mobility region (HMR); --a low mobility region (LMR) and --an intermediate mobility region (IMR). After the electrophoretic migration, the various cell fractions are identified. If human leucocytes are subjected to an electric field (40 volts/cm) it is possible to isolate several populations which differ by their membranes electric charge. The repartition of the neutrophiles granulocytes is twofold: --one fraction of high mobility (HMR) and --one fraction of low mobility (LMR). The meaning of these two populations is being discussed. Between these teo fractions is located the lymphocyte fraction which is represented by a single peak of intermediate mobility (IMR). Eosinophiles and monocytes are concentrated in low mobility fraction (LMR). With appropriate migration parameters (80 volts/cm, various component buffers) it is possible to obtain from lymphocytes, purified by density gradient, an electrophoretic separation of T and B lymphocytes population. Histograms obtained from quantitative measures (on collected cell fractions) show an unimodal distribution. When separated cells are characterized by three membranes markers (E. Rosettes, EAC Rosettes and surface immunoglobulins) the electrophoretic heterogeneity of B and T cells is then demonstrated. With E Rosettes (T cells) the majority of T lymphocytes is distributed in HMR and IMR. With EAC Rosettes and membrane immunofluorescence (B cells markers) the majority of B lymphocytes is found in the LMR. Thus an important enrichment of T and B sub-population is obtained, but contamination from one another still remains too important. More selective methods should lead to an improvement of this cell separation.