Low-Frequency Blood Group Antigens in Switzerland.

BACKGROUND: High-frequency blood group antigens (HFA) are present in >90% of the human population, according to some reports even in >99% of individuals. Therefore, patients lacking HFA may become challenging for transfusion support because compatible blood is hardly found, and if the patient carries alloantibodies, the cross-match will be positive with virtual every red cell unit tested. METHODS: In this study, we applied high-throughput blood group SNP genotyping on >37,000 Swiss blood donors, intending to identify homozygous carriers of low-frequency blood group antigens (LFA). RESULTS: 326 such individuals were identified and made available to transfusion specialists for future support of patients in need of rare blood products. CONCLUSION: Thorough comparison of minor allele frequencies using population genetics revealed heterogeneity of allele distributions among Swiss blood donors which may be explained by the topographical and cultural peculiarities of Switzerland. Moreover, geographically localized donor subpopulations are described which contain above-average numbers of individuals carrying rare blood group genotypes.

[Relapsing fever: an almost forgotten disease in focus again]. / Rückfallfieber.

Introduction | Relapsing fevers, transmitted by arthropods, are rarely encountered in Germany, thus they are often not considered as differential diagnosis in febrile patients. In the last months, more than fourty cases of louse-borne relapsing fever were diagnosed in asylum seekers in Germany. Some of the patients had to be admitted to intensive care units, one patient died despite therapy. Pathogen, disease and diagnosis | The causative agents are spirochetes of the genus borrelia, which can reach high densities in patient blood. Depending on the vector and the region, different species are prevalent worldwide. For diagnosis, appropriate techniques include direct detection by microscopy or PCR from EDTA-blood. Ordering such tests should not be delayed when there is suspicion for relapsing fever. Besides, malaria can also be excluded with microscopy of blood smears. Therapy | First-line antibiotics include tetracyclines and penicillin, acquired resistance has not yet been observed. Frequently patients develop a Jarisch-Herxheimer reaction shortly after initiation of therapy, requiring hospitalization or intensive care treatment. Managing the treatment exclusively in an outpatient setting is not recommended. Especially in migrants with febrile illness, relapsing fever is an important differential diagnosis.

Washing stored red blood cells in an albumin solution improves their morphologic and hemorheologic properties.

BACKGROUND: Prolonged storage of red blood cells (RBCs) leads to storage lesions, which may impair clinical outcomes after transfusion. A hallmark of storage lesions is progressive echinocytic shape transformation, which can be partially reversed by washing in albumin solutions. Here we have investigated the impact of this shape recovery on biorheologic variables. STUDY DESIGN AND METHODS: RBCs stored hypothermically for 6 to 7 weeks were washed in a 1% human serum albumin (HSA) solution. RBC deformability was measured with osmotic gradient ektacytometry. The viscosity of RBC suspensions was measured with a Couette-type viscometer. The flow behavior of RBCs suspended at 40% hematocrit was tested with an artificial microvascular network (AMVN). RESULTS: Washing in 1% albumin reduced higher degrees of echinocytes and increased the frequency of discocytes, thereby shifting the morphologic index toward discocytosis. Washing also reduced RBC swelling. This shape recovery was not seen after washing in saline, buffer, or plasma. RBC shape normalization did not improve cell deformability measured by ektacytometry, but it tended to decrease suspension viscosities at low shear rates and improved the perfusion of an AMVN. CONCLUSIONS: Washing of stored RBCs in a 1% HSA solution specifically reduces echinocytosis, and this shape recovery has a beneficial effect on microvascular perfusion in vitro. Washing in 1% albumin may represent a new approach to improving the quality of stored RBCs and thus potentially reducing the likelihood of adverse clinical outcomes associated with transfusion of blood stored for longer periods of time.

Albumin reverses the echinocytic shape transformation of stored erythrocytes.

The storage of red blood cells (RBCs) leads to storage lesions, which have a negative impact on the clinical outcome after transfusion. A hallmark of storage lesions is echinocytosis. Albumin may reverse this shape transformation, which was the topic of this study. Echinocytosis was generated by incubation of blood for 48 h at room temperature or in RBC units stored 48 days at 5°C. Human serum albumin was diluted in phosphate-buffered saline. RBCs were fixed in 1% glutaraldehyde and examined by light and scanning electron microscopy. The degree of echinocytosis was quantified by calculating the morphological index. Incubation and storage of RBCs led to an echinocytic shape transformation, which was reversible upon incubation in albumin solutions. This process was time-, concentration- and hematocrit-dependent. Treating RBC units at the end of their shelf-life by adding 20% albumin or washing them in 0.2% albumin reversed all degrees of echinocytosis towards discocytosis. In conclusion, albumin has the capacity to reverse echinocytosis generated by RBC storage. This observation may improve the quality of RBC units stored for longer periods of time.

Interaction of injectable neurotropic drugs with the red cell membrane.

The normal red blood cell (RBC) shape is a biconcave discocyte. An intercalation of a drug in the outer half of the membrane lipid bilayer leads to echinocytosis, an intercalation in the inner half to stomatocytosis. We have used the shape transforming capacity of RBCs as a model to analyse the membrane interaction potential of various neurotropic drugs. Chlorpromazine, clomipramine, citalopram, clonazepam, and diazepam induced a reversible stomatocytosis, phenytoin induced echinocytosis, while the anticonvulsants levetiracetam, valproic acid and phenobarbital had no effect. This diversity of RBC shape transformations suggests that the pharmacological action is not linked to the membrane interaction. We conclude that this simple RBC shape transformation assay could be a useful tool to screen for potential drug interactions with cell membranes.

Incidence of acute myocardial infarction after implementation of a public smoking ban in Graubünden, Switzerland: two year follow-up.

QUESTION UNDER STUDY: In the first year after implementation of a public smoking ban a significant decrease in the incidence of acute myocardial infarction (AMI) was observed in Graubünden. In the present study we analyzed the incidence of AMI in the second year of the ban. In addition, we investigated the contribution of smoking ban-unrelated factors to the reduced incidence of AMI incidence observed after enactment of the ban. METHODS: Data of all AMI patients who underwent coronary angiography at the Kantonsspital Graubünden, the only tertiary care hospital with a cardiac catheterization laboratory in Graubünden, between March 1st, 2009 and February 28th, 2010 were collected prospectively. Data were compared with those of the three preceding 12-month periods. We also estimated AMI incidence during the corresponding time period in Lucerne, a region with no smoke-free legislation, using data of the AMIS Plus registry. The influence of outdoor air pollution was analyzed with the help of official measurements of PM(10)- and NO(2)-concentrations in Graubünden. The prescription of lipid-lowering drugs was estimated by using sales figures in Graubünden and Lucerne. RESULTS: In Graubünden, the number of patients with AMI in the second year after adoption of the smoking ban was similar to that in the first year of the ban (188 vs. 183; P = ns) and significantly lower than in each of the two years preceding the ban (229 and 242, respectively; P <0.05 vs. each of the 12-month periods after the ban). Overall, the number of AMI patients in the two post-ban years was 21% lower than in the two pre-ban years. The reduction in the number of patients with AMI was most pronounced in non-smokers and individuals with known coronary artery disease. During the corresponding time period, no similar decrease in the incidence of AMI was observed in Lucerne. No association was found between the magnitude of outdoor air pollution and the incidence of AMI. During the observation period, the use of lipid-lowering drugs increased similarly in Graubünden and Lucerne. CONCLUSIONS: Compared with the two years preceding the implementation of a smoking ban, the incidence of AMI remained significantly reduced in the second year of the ban in Graubünden, whereas no similar reduction was seen in a comparable area without smoke-free legislation. Changes in outdoor air pollution or the use of lipid-lowering drugs did not substantially contribute to the decrease in the incidence of AMI that occurred after adoption of the ban in Graubünden.

Stored erythrocytes have less capacity than normal erythrocytes to support primary haemostasis.

Primary haemostasis is mediated by platelet aggregation. Red blood cells (RBCs) are involved in this process. We hypothesised that stored RBCs could have less capacity to support primary haemostasis. This was tested with RBC units from 17 healthy volunteers stored for 45 days. Fresh citrated blood was taken again from the same donors and platelet-rich plasma was prepared, in which RBCs were resuspended with a constant haematocrit (40%), but changing fractions of stored versus fresh autologous RBCs (0, 25, 50, 75, and 100%, respectively). A platelet function analyser PFA-100((R)) was used. In this instrument blood is aspirated through a membrane pore coated with collagen and either epinephrine (EPI) or ADP, which causes platelets to adhere, aggregate, and form an occluding plug, which stops blood flow and is measured as closure time (CT). We found that the CT increased with increasing fractions of stored blood. CT-EPI was 121 +/- 17 seconds [s], 129 +/- 32 s, 164 +/- 45 s (p < 0.000, ANOVA), 214 +/- 54 s (p < 0.0001), and 273 +/- 36 s (p < 0.0001) for 0, 25, 50, 75, and 100% stored RBCs. For CT-ADP the values were 91 +/- 22 s, 95 +/- 12 s, 101 +/- 13 s, 124 +/- 44 s (p = 0.004), and 191 +/- 72 s (p < 0.0001), respectively. We conclude that stored RBCs have less capacity than normal RBCs to support primary haemostasis by platelet aggregation in vitro, suggesting a decreased capacity of stored RBCs to bring platelets into close contact with the wall, which may contribute to sustained bleeding seen after mass transfusion.

PLTs of blood group A1 donors express increased surface A antigen owing to apheresis and prolonged storage.

BACKGROUND: In contrast to RBC transfusion, where ABO mismatch is potentially lethal, immunologic ABO matching has been considered less critical for PLTs. Nonetheless, PLTs bear ABO blood group antigens, some of them expressing very high levels. STUDY DESIGN AND METHODS: The expression of A antigen was investigated by flow cytometry on resting and stimulated human PLTs of 100 A and 10 O group donors, as well as on 17 PLT concentrates (PCs) after apheresis and daily during a 6-day storage, to determine possible changes in expression of A antigen on PLT surface. RESULTS: Considerable variation of A antigen expression on PLT surface of A1 group individuals was observed; A2 group PLTs could not be distinguished from O group PLTs. The variability of A antigen on A group PLTs also became evident on investigating PLT lysates by ELISA. A1 group PCs showed a significant increase of A antigen expression on their surface owing to apheresis (p = 0.001) and to storage (p = 0.0091). CONCLUSION: Apheresis and prolonged storage of A1 group PCs independently led to overexpression of A antigen on the PLT surface. This may make such PCs more susceptible to destruction by anti-A of O or B group recipients.