[Restoration of blood circulation in reperfusion of ischemic tissues]. / Vidnovlennia krovobihu pry reperfusiï ishemizovanykh tkanyn.

In experiment there were studied changes of the tissue blood circulation and microcirculation during postischemic reperfusion of skeletal muscles with various density of capillaries. It was established that reactive hyperemia, caused mainly by enhancement of extracapillary tissue blood flow. While persistence of durable arterial hypertension the capillaries quantity and potential volume of microcirculatory bed are reducing, negatively influencing the blood circulation restoration process during postischemic reperfusion. In chronic ischemia the potential volume of microcirculation is increasing, securing complete restoration of blood circulation in postischemic reperfusion.

["Reperfusion collapse" phenomenon during post-ischemic reperfusion in experiment]. / Fenomen "reperfuziinoho kolapsu" pid chas postishemichnoï reperfuziï v eksperymenti.

Postischemic changes of central and regional hemodynamic while various reperfusion regimens have been studied on animal experimental model. We had revealed that despite vasodilatation, peripheral vascular resistance in the postischemic extremity rises, as a result of reperfusion by the lowered perfusion volume. Such phenomenon has been named as "reperfusion-collapse". In spite of the microcirculation disorders progression there have been no significant rising of the peripheral vascular resistance as well as worsening of the regional hemodynamic indexes in the postischemic limb during reperfusion by either normal or increased perfusion volume.

[Erythrocytes after cryopreservation with HES: molecular, structural and functional characteristics]. / Erythrozyten nach Kryokonservierung mit HES. Molekulare, strukturelle und funktionelle Eigenschaften.

The use of hydroxyethylstarch (HES) as an alternative to glycerol for cryopreservation of erythrocytes is presented. Immediately after thawing erythrocytes showed alterations in the membrane skeleton and a lowered rigidity of their membrane. However, a few minutes after resuspension in a physiological salt solution the initial poicilocytosis changed back to normocytotic forms. Intravital microscopy of the dog's mesentery revealed a homogeneous distribution of labeled previously cryopreserved erythrocytes in the capillary bed. The lowering of the ATP-level in the erythrocyte by about 20 to 40% was seen to be harmless, because the ATP-turn over rate was unchanged and the glucose support by the GluT 1 carrier was seen to be guaranteed. There was no decrease in the 2,3-DPG level on one hand, but a shift to the right in the O2-association as well as dissociation functions; the saturation capacity of hemoglobin with O2 on the other hand was constant. Free radical oxygen species, generated as a consequence of the freezing/thawing process, were inactivated by the erythrocyte's own antioxidation system. The 24-hour post-transfusion survival in dog amounted to about 95% and the in vivo-life time was normal. The hemolysis of human erythrocytes after thawing was about 5%. Most methodological and scientific problems concerning erythrocyte cryopreservation are considered to be solved. After official permission for use in humans, major benefits to many fields in surgery are expected: no more short-cuts in blood supply, practically complete exclusion of infectious risks, even unlimited use of autologous blood.

Action of hydroxyethyl starch (HES) on the activity of plasmatic clotting factors.

Studies were carried out on the effects of different doses of hydroxyethyl starch 200/0.5 (HES) on plasma clotting factors in dogs, as an animal model for the human clotting system. In 8 German shepherd dogs 15% of the total blood was isovolemically substituted either by Ringer's solution with lactate alone (controls) or with 0.6, 1.3, 1.9, 2.5 g HES/kg b.w. Immediately after the infusion, the HES concentration in the recipients' plasma amounted to 8 mg/ml up to 38 mg/ml. In the following 6 h, the HES decreased to 25% in each case. It was found that the higher the plasma HES content was, the lower the haematocrit. Neither the thrombin-nor the batroxobin-time showed any significant change, irrespective of the plasma HES concentration. The prothrombin-time was decreased directly after the infusion in parallel to the haematocrit. The single clotting factors FI, FII, FV, FVII, FVIII, FX, and FXII behaved approximately in the same way: their activities directly after infusion, but also 6 h later, were lowered in proportion to the amount of HES infused. The loss of factor activity correlated with the volume-expanding effect of HES shortly after the infusion, but not 6 h later. It is concluded that there are two different modes of HES action on clotting factors: the dilution by plasma volume expansion and a non-dilutional action. Cautious handling might be required in patients with clotting disturbances as well as in long-term treatment.

[Cardiovascular risk factors in diabetic nephropathy]. / Kardiovaskuläre Risikofaktoren bei diabetischer Nephropathie.

BACKGROUND: Diabetic nephropathy is associated with increased cardiovascular mortality. This may be contributed to by changes in plasma lipids, fibrinogen and hemorheology. Cardiovascular autonomic dysfunction, which is related to an increased incidence of arrhythmic death, may also play a role. PATIENTS AND METHODS: Therefore, we investigated in 58 IDDM-patients with none (n = 28), incipient (albuminuria 30 to 300 mg/day, n = 11) and overt clinical nephropathy (albuminuria > 300 mg/day, n = 19) plasma concentrations of lipoproteins and fibrinogen, plasma viscosity, erythrocyte aggregation and erythrocyte rigidity. Assessments of neuropathy included tibial nerve motor conduction velocity, perception of vibration, beat-to-beat variation during rest and during forced respiration, heart-rate response to Valsalva maneuver and heart-rate response to standing (30:15). RESULTS: Patients with clinical overt nephropathy had, compared to those without nephropathy, significantly higher concentrations of LDL-cholesterol, triglycerides and fibrinogen, significantly lower concentrations of HDL-cholesterol and significantly higher plasma viscosity, erythrocyte aggregability and erythrocyte rigidity. Regarding the assessments of neuropathy we found in patients with nephropathy, compared to those without nephropathy, significantly reduced tibial nerve motor conduction velocity, reduced perception of vibration thresholds and reduced heart rate variability during rest, during forced respiration, in response to Valsalva maneuver and in response to standing. In diabetic patients with microalbuminuria erythrocyte aggregability and erythrocyte rigidity were significantly higher and heart rate variability during rest was significantly lower than in patients without nephropathy. CONCLUSION: In clinical overt nephropathy there is an aggregation of different cardiovascular risk factors, namely, disturbances in lipoprotein concentrations, increased fibrinogen concentration and disturbances in hemorheology. Furthermore marked deterioration in peripheral and autonomic cardial nerve function in these patients is evident accounting for a part of the greatly increased cardiovascular mortality of these patients.

[Changes in blood rheology and microcirculation after preparatory combined thrombocytapheresis and plasmapheresis]. / Veränderungen der Blutrheologie und Mikrozirkulation nach präparativer kombinierter Thrombozytapherese und Plasmapherese.

INTRODUCTION: Because of anticoagulation, changes in blood composition, and--perhaps--extracorporeal circulation, donor apheresis should cause alterations in hemorheology and hence in the perfusion of the microvasculature. MATERIAL AND METHODS: 19 regular blood donors were included. According to our standard protocol for automated collection of blood components with the MCS 3p cell separator, we harvested 1 unit of platelets and 2 units of plasma in each case. Prior to, 1 h after, and 24 h after donation, the following parameters were measured: total serum protein (tsp), hematocrit (hc), whole blood and plasma viscosity (wbv/pv), red cell aggregability (rca) and blood flow velocity of the nail-fold capillaries (bfv). RESULTS: The following parameters decreased 1 h/24 h after donation: tsp (p < 0.001/p = 0.008), elastic wbv (p = 0.018/p < 0.001), viscous wbv (p = 0.85/p = 0.0031), pv (p < 0.001/p < 0.001), static rca (p < 0.001/p = 0.0073), dynamic rca (p < 0.001/p = 0.017). The hc showed an initial increase (p < 0.001) with a subsequent overshooting decrease after 24 h (p < 0.001). 1 h after donation bfv raised (p = 0.0065). It decreased after 24 h and remained only slightly higher than the initial level (p = 0.27). CONCLUSIONS: Automated combined collection of platelets and plasma gives rise to: i) Improvement of rheological properties of the donor's blood and increased bfv of his nail-fold capillaries within the 1st h after apheresis. ii) 24 h after donation the improved hemorheological properties remain demonstrable, but the bfv of nail-fold capillaries declines and shows a trend toward the starting-point. iii) Taken together, this is possibly reflecting adapted hemodynamic and vasoconstrictor regulation for altered hemorheological conditions.

[Therapeutic thrombocytapheresis--effect on hemorheologic parameters]. / Therapeutische Thrombozytapheresen--Wirkung auf hämorheologische Parameter.

Common features of all myeloproliferative diseases (CMPE) are a markedly increased number of platelets and restrictions in the subjective feeling of the patients, comprising symptoms like nausea, headache, sensory deficits and transient paresis. Meanwhile, it has been shown that platelet pheresis (mTD) does not only reduce platelet counts sufficiently but also results in an impressive relief of the subjective complaints. To test the part that rheological mechanisms play hereby, relevant rheological parameters in the blood of 22 CMPE patients and of 8 healthy platelet donors as controls were analyzed before and after treatment with an AS-104 cell separator. Concerning the viscosity of whole blood und the filterability of erythrocytes, there was seen neither a difference between the patients and the controls, nor before and after mTD. As a result of treatment of patients, the moderately raised plasma viscosity was normalized, whereas the aggregation of erythrocytes was significantly lowered. It is concluded that there is an influence of hemorheological conditions on the patient's subjective feeling. These would originate in neurological dysfunctions caused by CMPE-induced restrictions in cortical microcirculation. The erythrocyte aggregation, lowered by mTD, would cause an improvement of microcirculatory fluidity and would, in consequence, abolish the neurological symptoms.

[Electron microscopy study of HES cryopreserved erythrocytes]. / Elektronenmikroskopische Untersuchung von HES-kryokonservierten Erythrozyten.

Using electron microscopy (EM), it was examined whether cryopreservation with HES causes shape changes of erythrocytes. Each of 11 erythrocyte suspensions (Hct = 40; HES 200,00/0.5/12.5%; 60 mM NaCl) was separated into 40-ml samples, cooled down to -196 degrees C and finally stored. In addition, 11 samples were stored at -80 degrees C for 3 months. The preparation for EM was done immediately after thawing or in case of native cells shortly after donation. On EM micrographs, there was no visible difference between native and cryopreserved erythrocytes. In every case the preparations showed normocytes, either as single cells or having attracted other ones, forming rouleau. Packed cells were attached tightly to each other without any gap in between. The tangent count method neither revealed an excess of convexity nor of concavity. The erythrocyte membrane looked normal, and the cytoplasmatic space was filled with electron-dense material (hemoglobin) homogeneously; Heinz bodies were not seen. Scanning microscopy portrayed native as well as cryopreserved cells as discocytes with the characteristic bioconcave resting shape of human erythrocytes. It is concluded that cryopreservation of erythrocytes with HES does not cause shape changes. Therefore, a sequestration into the reticulo-endothelial system (RES) by means of identification of morphological abnormalities may not be expected.

Hemorheology, plasma protein composition and von Willebrand factor in type I diabetic nephropathy.

Patients with IDDM, especially those with albuminuria are at high risk for macrovascular and microvascular complications. Besides the major classic risk factors altered hemorheology may also play a role. Plasma viscosity, erythrocyte aggregation and erythrocyte deformability are the major determinants of blood flow in the microcirculation. Therefore, these hemorheological parameters and plasma protein composition were evaluated in 58 IDDM-patients with none (N0), incipient (N1: albuminuria 30-300 mg/day) and overt clinical nephropathy (N2: albuminuria > 300 mg/day). As an estimate of endothelial injury plasma levels of von Willebrand Factor (vWF) were investigated. Patients with incipient and clinical nephropathy exhibited increasing blood levels of fibrinogen (N0 = 2.47 +/- 0.09, N1 = 2.71 +/- 0.15, N2 = 3.49 +/- 0.24 g/l, p < 0.001), alpha 2-macroglobulin (N0 = 257 +/- 11, N1 = 251 +/- 21, N2 = 382 +/- 43 mg/100 ml, p < 0.01) and haptoglobin (N0 = 174 +/- 16, N1 = 216 +/- 39, N2 = 278 +/- 36 mg/100 ml, p < 0.05), whereas serum albumin concentration decreased (N0 = 5.1 +/- 0.1, N1 = 4.7 +/- 0.1, N2 = 4.1 +/- 0.2 g/100 ml, p < 0.001). In the same patients erythrocyte aggregation (N0 = 10.0 +/- 0.4, N1 = 12.1 +/- 0.5, N2 = 12.9 +/- 0.6, p < 0.001), plasma viscosity (N0 = 1.34 +/- 0.01, N1 = 1.38 +/- 0.02, N2 = 1.40 +/- 0.02 mPas, p < 0.05) and erythrocyte rigidity (N0 = 0.05 +/- 0.01, N1 = 0.15 +/- 0.05, N2 = 0.09 +/- 0.02, p < 0.05) were increased, predominantly in those with overt clinical nephropathy. Erythrocyte aggregation was positively correlated with plasma concentrations of fibrinogen (r = 0.65, p < 0.001) and alpha 2-macroglobulin (r = 0.35, p < 0.05), but negatively with plasma albumin concentration (r = -0.49, p < 0.001). Plasma viscosity was positively correlated with plasma concentrations of fibrinogen (r = 0.46, p < 0.001) and haptoglobin (r = 0.46, p < 0.001). Von Willebrand Factor levels were higher in patients with overt clinical nephropathy (N0 = 126 +/- 8, N1 = 136 +/- 12, N2 = 163 +/- 14%, p < 0.09, PN0-N2 < 0.05). A significant correlation between vWF and the rheological determinants could not be detected. These data demonstrate that blood rheology is profoundly altered in patients with IDDM and nephropathy. Elevated levels of vWF may indicate endothelial damage, and changes in plasma viscosity as well as erythrocyte aggregability seem to be the result of altered plasma protein composition due to proteinuria. These abnormalities in hemorheology may be an aggravating factor promoting microvascular and macrovascular damage in patients with type I diabetes mellitus and nephropathy.

[Lipid peroxidation and hemolysis in HES cryopreserved erythrocytes]. / Lipidperoxidation und Hämolyse bei HES-kryokonservierten Erythrozyten.

Using malondialdehyde (MDH) as an indicator of lipid peroxidation it was examined, whether oxygen radicals could be an origin of freeze-induced weakness of HES-cryopreserved erythrocytes. Each of 11 erythrocyte suspensions (Hct = 40; HES 200,000/0.62/12.5%; 60 mmol NaCl) was separated into 40 ml samples, cooled down to -196 degrees C und stored at -80 degrees C, finally. Samples were thawed after 1, 2, 3 und 6 months storage and besides that, one sample having remained at -196 degrees C (LN2). The MDH content (1.5 mumol/l Ery unwashed; 0.4 mumol/l Ery washed) amounted to 3.4 mumol/l Ery after LN2 storage, to 4 mumol/l Ery after 1 und to 8 mumol/l Ery after 6 months at -80 degrees C. Similarly, the MDH generation rate at -80 degrees C increased with storage time. The membrane fragility (1 in freshly drawn erythrocytes; 1.3 in erythrocytes out of LN2) rose from 1.6 after 1 month to 2.4 after 6 months. MDH content and membrane fragility were correlated linearly (r = 0.98). It is concluded that increased superoxide formation is mediated by freezed-induced oxidation of Hb-bound Fe. This allows peroxidation of membrane lipids which in consequence causes hemolysis.

[Storage-induced rheologic and biochemical changes in erythrocyte concentrates with added solution and possible correlations]. / Lagerungsbedingte rheologische und biochemische Veränderungen von Erythrozytenkonzentraten in additiver Lösung und deren mögliche Zusammenhänge.

Rheological integrity is one of the essentials for red blood cells (rbc) in capillary circulation. The influences of metabolical/biochemical changes of rbc on their rheological properties are well known, but (to our knowledge) until now there are no published studies, which cover both quality aspects of packed rbc (prbc) in additive solutions. According to our standard operating procedures (SOP) we prepared prbc in additive solution (SAG-M) and plasma from 16 regular blood donations. The buffy coat was discharged. Following parameters were measured on day 1, 14 and 28: extracellular pH, ATP and 2,3-DPG content of rbc, prbc-viskosity, -filterability, -aggregability and filter clogging rate. For examination of the filterability a 5% rbc-suspension in phoshate buffered solution was prepared, the remaining tests were performed with rbc-samples adjusted to a hematokrit of 40% with fresh frozen autologous plasma. In correlation with the depletion of ATP a decrease of rbc flexibility and changes of shape (for example spherocytosis) are well known from the literature. Our results confirm the assumed time dependent deterioration of rheological patterns of prbc in SAG-M, reflecting in an increase of rbc-viscosity and filter clogging rate and a decrease of rbc-filterability and -aggregability. We also observed the expected decrease of pH, ATP and 2,3-DPG during storage. The influences of biochemical changes on rheological alterations are discussed. Therefore we recommend on demand rheological examinations in addition to metabolical/biochemical analyses for an extended quality assurance program, for instance for testing new additive solutions or major changes of SOP.

[Elimination of hydroxyethyl starch after autologous retransfusion of cryopreserved erythrocytes]. / Elimination von Hydroxyethylstärke nach autologer Retransfusion von damit kryokonservierten Erythrozyten.

In the case of the biodegradable cryoprotectant hydroxyethyl starch (HES) no deglycerolization process is required prior to the transfusion of frozen red blood cells (RBC). In a first study the elimination of an HES 200,000/0.62 from the plasma of 6 dogs was investigated by means of a novel HPLC-GFC method. 16% of the blood volume were replaced by autologous HES protected frozen/thawed RBC. In a second study the HES concentration in the plasma of 7 healthy volunteers was determined following the substitution of 8% of the blood volume, but a washing step has been performed to reduce the concentration of the cryoprotectant (HES 200,000/0.5). In a third study, however, this step was omitted. The elimination of the HES followed always first order kinetics. In the case of the transfusions without postthaw washing in dogs and humans, the initial plasma concentrations amounted to 2.11 +/- 0.15 g/dl and 0.75 +/- 0.26 g/dl, respectively. The corresponding value for the washed preparations was less than 0.03 g/dl. Within 4-5 h the concentrations dropped to less than 50% of the initial values. The 9-hour value was less than 35% (dogs), the 20-hour value about 15% (humans) of the initial concentration. As HES is primarily eliminated via the kidneys, within this period the concentrations of HES in the urine dropped from 4.3 +/- 2.11 g/dl to less than 0.03 g/dl (humans, no washing step). In conclusion, the elimination of the accompanying cryoprotectant HES was no problem in the concentrations applied. A simple washing step with isotonic saline, however, effectively reduced the concentration of the extracellular cryoprotectant HES far below critical levels.

[Characterization of 24-hour survival rate and duration of survival of hydroxyethyl starch cryopreserved erythrocytes after autologous transfusion in the dog]. / Charakterisierung der 24-Stunden-Uberlebensrate und Lebensdauer von mittels Hydroxyethylstärke kryokonservierten Erythrozyten nach autologer Transfusion im Hund.

BACKGROUND: Cryopreservation of erythrocytes using hydroxyethyl starch (HES) as cryoprotecting additive could result in a nearly unlimited storage stability of preserved red cells. In addition, it would allow its immediate use for transfusion. In order to assess the therapeutic efficacy of erythrocytes cryopreserved with HES, their 24-hour post-transfusion survival and long-term survival was evaluated. MATERIALS AND METHODS: The experiments were carried out with dog erythrocytes as an animal model for human erythrocytes. To each of 6 German shepherd dogs a 15-ml sample of erythrocyte suspension, labeled with 51Cr (25 microCi) after thawing, was autologously injected. Caused by hemolysis 29% of the formerly cryopreserved erythrocytes have not been labeled. To each of 6 control animals 15 ml of a suspension of freshly drawn and 51Cr-labeled erythrocytes was injected. The 51Cr radioactivity in later taken blood samples was a measure for the number of injected erythrocytes having remained in the circulation until the moment of blood withdrawal. The effect of cryopreservation was assessed by comparison of the test group with the control group. RESULTS: In both groups 30% of the applied cells left the circulation within 30 min. This was effected by pharmacological enlargement of the dogs' spleen and not by hemolysis of the erythrocytes. After the first 24 h all of the cryopreserved labeled erythrocytes had survived to the same amount (> 95%) as the labeled fresh red cells. Between 12 h and 20 days after injection, in both groups the 51Cr activity decreased exponentially by 4.8 and 4.5%/d. This difference was not significant. The area under the curve amounted to 1253 and 1257% d, respectively. CONCLUSIONS: There exists a subpopulation of red cells that is destroyed by freezing stress. As a result the freed stroma would be a serious transfusion risk. All erythrocytes having survived the cryopreservation procedure resemble the fresh erythrocytes with regard to the in-vivo survival; their therapeutic efficacy is not impaired. In the context of in-vitro results with human erythrocytes it can be expected that at the present developmental state of the cryopreservation procedure at least 93% of the human erythrocytes cryopreserved with HES have a normal 24-hour and long-term post-transfusion survival.

Involvement of liver in the decompensation of hemorrhagic shock.

In a hemorrhagic shock model without adequate volume resuscitation we investigated the question whether a biochemical stabilization of liver function by applying 2-mercaptopropionyl-glycine (2MPG) may influence the shock dynamics especially the transition from compensated to decompensated shock and the development of multiple organ failure (MOF). The application of a bolus of 10 mg/kg 2MPG just after hemorrhage had significantly beneficial effects on shock dynamics. All measured blood parameters demonstrate a less severe liver dysfunction. We found a decisive recovery of systemic pH, prolonged high levels of blood glucose, a better ammonia detoxification, arterial ketone ratios (acetoacetate/beta-OH-butyrat) above about 0.25, and a significantly increased survival time from 200 +/- 10 min to more than 240 min after hemorrhage. Decompensation of the 2MPG group started about 60 min after decompensation of the shock group. The transition to decompensation was combined in the shock group as well as in the 2MPG group with a severe liver dysfunction indicated by an arterial ketone ratio below .25. Decreasing levels of blood thiobarbituric reactive material in compensated shock of both groups demonstrate that production of free radicals did not primarily cause decompensation, but increasing levels of thiobarbituric reactive material during decompensation seems to be one of the factors mediating MOF. Our data support the hypothesis of the liver being a barrier against decompensation of shock and MOF.

[The effect of combolen on the erythrocyte distribution in the dog]. / Die Wirkung von Combelen auf die Erythrozytenverteilung im Hund.

The effect of Combolen (3.9 mg/kg bw s.c.) on the distribution of erythrocytes in dogs was investigated. After application of Combolen, the hematocrit of the animals decreased exponentially within 1 h by 21%. The reversal of the reduction began from 2 h after the time of application, amounting to 4% within the first day and finishing by the fourth day. After injection of 51Cr-labelled erythrocytes, radioactivity in the circulation of Combolen-treated dogs decreased exponentially within 2 h by at least 30%. It was concluded that the dog's spleen, under physiological conditions, contains about 10% of the animal's blood. The time-courses of the decrease of hematocrit and radioactivity in the circulation were found to be very similar. In accordance with this observation, a high correlation (r = 0.97) between the level of radioactivity after injection of radio-labelled erythrocytes and the corresponding hematocrit values after application of Combolen was found. After application of erythrocytes, labelled with 99mTc, an extensive distribution from the circulation into the spleen was observed by scintigraphy. This process can be understood by using a closed-compartment model. An equation, based on this model, describes the observed time course of the hematocrit values, as well as the number of 51Cr-labelled erythrocytes, in Combolen-treated dog. Presumably, the observed effect of Combolen is the result of the relaxation of the smooth muscle cells in the trabeculae of the spleen, caused by central-nervous depression of sympathetic tone. Combolen seems to be a suitable tool in pre-clinical testing of a novel blood preserve with dog as a test animal. Its potent ability to eliminate erythrocytes from circulation is distinguishable from the sequestration of damaged red cells. Furthermore, its ability to prevent the spleen from uncontrolled hematocrit modulating actions in addition to its sedative effects is considered to be an invaluable advantage.

[Cryopreservation of erythrocytes using hydroxyethyl starch: in vivo results of an autologous retransfusion model in humans]. / Kryokonservierung von Erythrozyten mit Hydroxyethylstärke: In-vivo-Ergebnisse im autologen Retransfusionsmodell beim Menschen.

The cryopreservation of human red blood cells (RBC) can be greatly beneficial in certain situations such as for rare blood groups, problems due to multiple antibodies, and as an interim aid during temporary shortages. Additionally, cryopreserved erythrocytes may be useful in cases of civil or military disasters. Frozen/thawed autologous RBC are of particular interest as a supplement to liquid storage for elective operations (e.g. orthopedics, vascular and transplantation surgery) to extend the preoperative collection period, which is otherwise limited to 7 weeks. In this study using 7 healthy volunteers, 500 ml of whole blood was replaced by a suspension of cryopreserved autologous RBC [2 aliquots of 216 ml each, hematocrit (HCT) 43 +/- 2% (v/v), HES (hydroxyethyl starch) concentration 11.5% (w/w)]. No washing step was performed after thawing. Viability of the red cells after thawing in terms of saline stability reached 91.9 +/- 0.7% (n = 4). In all 7 cases the frozen/ thawed autologous RBC were tolerated very well. No adverse reactions could be detected. A slight posttransfusional leukocytosis as well as a moderate increase in LDH and bilirubin were observed, but these effects disappeared within 20 h. The concentrations of platelets, electrolytes, urea, protein and creatinine within their physiological ranges. The activities of the liver enzymes and the coagulation parameters investigated remained unchanged. Initially the level of free plasma hemoglobin increased by a factor of 2. Then it decreased within 20 h, accompanied by a restoration of haptoglobin. More than 85% of the HES was eliminated from the plasma within the 1st day.

[Cryopreservation of human erythrocytes with hydroxyethyl starch (HES)--Part 2: Analysis of survival]. / Kryokonservierung von Human-erythrozyten mit Hydroxyethylstärke (HES)--Teil 2: Vitalitätsanalytik.

Red blood cells (RBC) were obtained from 5 whole blood units by centrifugation and were purified using a simple washing procedure. Hematocrit and HES concentration in the 108-ml samples to be frozen were adjusted to 40% (v/v) and 12% (w/w), respectively. Cooling was performed by submerging into liquid nitrogen using containers to generate a flat sample geometry (3 mm thickness). After thawing in a shaking water bath, HES and free hemoglobin were removed in a simple washing step. To investigate the influence of the resuspension medium, the RBC were transferred into freshly drawn autologous plasma and into Locke's solution. Survival after thawing in terms of saline stability reached 86.3 +/- 2.3%. The cryopreservation procedure caused no major changes with regard to osmotic fragility, 2,3-DPG or intracellular Na+ and K+. ATP was reduced by 16%, but this had completely recovered after 3 h resuspension in autologous plasma. Some morphological changes present after thawing (e.g. stomatocytes, echinocytes) also recovered after 1.5 h. In conclusion, those RBC which survived the preservation process can be considered to be fully viable with regard to the parameters investigated.

[Cryopreservation of erythrocytes with hydroxyethyl starch. In vitro results leading to an autologous retransfusion model in the dog]. / Kryokonservierung von Erythrozyten mit Hydroxyethylstärke (HES). In-vitro-Ergebnisse auf dem Weg zum autologen Retransfusionsmodell beim Hund.

Although the effectiveness of hydroxyethyl starch (HES) as a cryoprotectant for human red blood cells (HRBC) is well known, no clinical application has evolved so far. In contrast to glycerol HES has the advantage of causing no hemolysis per se. This offers the opportunity of a one-step procedure without a time consuming postthaw washing procedure prior to transfusion. In this study the in vitro results obtained with red blood cells from 8 dogs (DRBC) are reported and compared to HRBC (n = 5). It turned out that DRBC had a similar 2,3-DPG and a lower ATP content. Postthaw survival in terms of saline stability differed markedly (67 +/- 6 and 86 +/- 2%, respectively). DRBC were more susceptible to hypotonic stress than HRBC. Nevertheless, after cryopreservation 91% (HRBC) and 92% (DRBC) of the original 2,3-DPG were found in the thawed RBC concentrates.

[Is there a noticeable temporary protective function of homologous skin grafts of variable thickness in deep burns against the effect of atmospheric oxygen?]. / Gibt es eine unterschiedliche temporäre Schutzfunktion verschieden dicker homologer Hauttransplantate auf tiefen Verbrennungswunden gegen die Einwirkung atmosphärischen Sauerstoffes?

The injurious influence of atmospheric oxygen upon healing of large wound areas for instance of burn wounds is well known, in differently thick skin grafts different protective functions can be demonstrated. Experiments show the isolation functions of the full-thickness on the one and split skin grafts on the other hand in burn wounds by measuring the subcutaneous pO2: under temporary full-thickness grafts there are with regard to the atmospheric oxygen clearly lower oxygen partial pressures than under split skin grafts.