An alternative method for Plasmodium culture synchronization.

Since the synchronization of Plasmodium falciparum has become an essential tool in research, we have investigated the use of a commercial gelatine solution, Plasmion, to replace Plasmagel, which is now difficult to obtain. This method also avoids the use of techniques based on Percoll-glucose gradients. The Plasmion-based technique proved to be a good method and could become an alternative to Plasmagel.

El polietilenglicol como agente antiagregante en la preparación de microesferas de gelatina con celecoxib / Polyethylene glycol as a de-aggregating agent in the preparation of colecoxib loaded gelatin microspheres

Se prepararon microesferas de gelatina con elevada eficiencia de captura mediante el método de reticulación química por emulsificación, utilizando polietilenglicol como agente antiagregante. Para la reticulación de la gelatina se utilizaron dos agentes de reticulación diferentes: formaldehído y glutaraldehído. Las microesferas preparadas se caracterizaron mediante microscopía electrónica de barrido según la eficiencia de captura, el tamaño de las partículas, la liberación de fármaco in vitro y la morfología. Los estudios de espectrometría FTIR indicaron la ausencia de interacción química entre la gelatina y el PEG. El PEG actúa únicamente como barrera para impedir la agregación de las microgotas de gelatina presentes en la fase interna de la emulsión durante la preparación. Los estudios de liberación de fármaco in vitro indicaron que las microesferas reticuladas mediante glutaraldehído presentaban un índice de liberación inferior a las reticuladas con formaldehído La liberación repentina se observó en ambos casos. En general, aproximadamente un 40% del fármaco se libera en la primera hora, seguido de una liberación lenta durante unas 96 horas en el caso de las microesferas reticuladas con glutaraldehído

Gelatin microspheres with high entrapment efficiency were prepared using emulsification chemical cross- crosslinking linking method using polyethylene glycol as a de-aggregating agent. Two different cross-linking agents viz. formaldehyde and glutaraldehyde were used for cross-linking gelatin. The prepared microspheres were characterized for entrapment efficiency, particles size, in-vitro drug release and the morphology was studied by scanning electron microscopy. The FTIR studies indicated that there is no chemical interaction between gelatin and PEG. PEG acts only as a barrier to the aggregation of the gelatin microdrops present in the internal phase of the emulsion, while preparation. In-vitro drug release studies indicated that the microspheres cross-linked using glutaraldehyde showed slower release rate than those cross-linked with formaldehyde. Burst release was observed in both the cases. In general, about 40% of the drug is released in the first hour followed by a slow release for about 96 hours for glutaraldehyde cross-linked microspheres

Resuscitation with modified gelatin causes higher bacterial translocation in experimental sublethal hemorrhagic shock.

The effect of colloidal solutions on bacterial translocation was studied. Sublethal hemorrhagic shock was established by blood withdrawal until the mean arterial pressure fell to 40 mmHg within 15 min on 36 adult Wistar Albino rats. Resuscitation was performed using four different solutions with the same amount of blood. Group I (n = 9) 0.9% NaCl, Group II (n = 9) 10% dextran 40, Group III (n = 9) 6% hydroxyethyl starch, Group IV (n = 9) 4% modified fluid gelatin. Before resuscitation and after anesthesia blood samples were drawn to analyze pH, PCO2, PO2, SaO2, HCO3 and ABE values. Twenty-four hours after anesthesia laparotomy was performed to obtain tissue samples of the liver, spleen and mesenteric lymph nodes. Samples were cultured on EMB and blood agar media. Results were analyzed with the one-way ANOVA and Post-hoc test (Tukey's HSD). The translocated bacteria were mainly Eschericia coli and three grew in Group I, two in Group II, three in Group III and six in Group IV. Although there was a trend in difference in bacterial translocation rates among groups, statistical analyses revealed no difference among groups (p < 0.05). It can be concluded that resuscitation with modified gelatin causes higher bacterial translocation in an experimental sublethal hemorrhagic shock model.

Agitated saline versus polygelatine for the echocardiographic assessment of patent foramen ovale.

BACKGROUND: The choice of the optimal echo contrast agent could be of relevance for the detection of a patent foramen ovale (PFO). This study compares agitated saline solution and oxypolygelatine (OXY) with respect to their ability to detect a PFO. METHODS: A total of 34 patients (13 women, age 45 +/- 16 years) underwent both transthoracic and transesophageal echocardiography. The appearance of contrast and the presence of a PFO was assessed visually and by acoustic densitometry for both agents. RESULTS: The sensitivity of the detection of a PFO (22 patent, 65%) was 71% with saline versus 84.6% for OXY. Maximum, mean acoustic densitometry grayscale intensity values and the duration of opacification was significantly higher for OXY versus saline for all chambers. CONCLUSIONS: OXY has superior echo properties that translate into a higher sensitivity for the detection of a PFO. The choice of the optimal agent must be considered for clinical routine and research studies.

Metabolic mapping of proteinase activity with emphasis on in situ zymography of gelatinases: review and protocols.

Proteases are essential for protein catabolism, regulation of a wide range of biological processes, and in the pathogenesis of many diseases. Several techniques are available to localize activity of proteases in tissue sections or cell preparations. For localization of the activity of matrix metalloproteinases, in situ zymography was introduced some decades ago. The procedure is based on zymography using SDS polyacrylamide gels containing gelatin, casein, or fibrin as substrate. For in situ zymography, either a photographic emulsion containing gelatin or a fluorescence-labeled proteinaceous macromolecular substrate is brought into contact with a tissue section or cell preparation. After incubation, enzymatic activity is revealed as white spots in a dark background or as black spots in a fluorescent background. However, this approach does not allow precise localization of proteinase activity because of limited sensitivity. A major improvement in sensitivity was achieved with the introduction of dye-quenched (DQ-)gelatin, which is gelatin that is heavily labeled with FITC molecules so that its fluorescence is quenched. After cleavage of DQ-gelatin by gelatinolytic activity, fluorescent peptides are produced that are visible against a weakly fluorescent background. The incubation with DQ-gelatin can be combined with simultaneous immunohistochemical detection of a protein on the same section. To draw valid conclusions from the findings with in situ zymography, specific inhibitors need to be used and the technique has to be combined with immunohistochemistry and zymography. In that case, in situ zymography provides data that extend our understanding of the role of specific proteinases in various physiological and pathological conditions.

Biocompatibility of NGF-grafted GTG membranes for peripheral nerve repair using cultured Schwann cells.

We previously developed a biodegradable composite with potentially good biocompatibility composed by tricalcium phosphate and gluataraldehyde cross-linking gelatin (GTG) with good mechanical property feasible for surgical manipulation. The purpose of this study was to evaluate the feasibility of immobilizing nerve growth factor (NGF) onto the composite (GTG) with carbodiimide (GEN composite). Cultured Schwann cells were seeded onto the GTG and GEN composites. For comparison, GTG membrane soaked in NGF solution without carbodiimide (GN composite) as cross-linking agent was also used to culture Schwann cells. Cell morphology was observed by a scanning electron microscope. Cell survival, cytotoxicity and cellular metabolism on the NGF-grafted GTG membrane were assessed quantitatively in terms of cell protein content, leakage of cytosolic lactate dehydrogenase (LDH) activity and by the well-established MTT assay, respectively. The result of LDH study did not show significant difference among GTG, NGF-modified GTG and control group. This indicated that GTG composite, whether cross-linking with NGF or not, has little cytotoxic effect. Comparing the protein content and MTT assay among GEN, GN composite and control group, the data confirmed more attachment of Schwann cells on GEN composite. Although GTG cross-linking with NGF did not promote Schwann cell proliferation, the techniques we used in this study provided a method to fabricate a novel biomaterial incorporation of Schwann cells and covalently immobilized NGF.

Ringer's solution but not hydroxyethyl starch or modified fluid gelatin enhances platelet microvesicle formation in a porcine model of septic shock.

BACKGROUND: Sepsis is associated with volume deficit and clotting system activation. Platelet activation in sepsis results in an increased formation of microvesicles, which in turn, have been associated with increased mortality. We hypothesized an effect of different volume replacement solutions on platelet-derived microvesicle formation in septic shock. METHODS: Anaesthetized, mechanically ventilated and multi-catheterized pigs received 1 g kg(-1) body weight faeces into the abdominal cavity to induce sepsis and were observed over 8 h. Five animals in each group received volume replacement therapy with modified fluid gelatin 4% or 8% (MFG4%, MFG8%), 6% hydroxyethylstarch (HES) 200/0.5 or Ringer's solution (RS) to maintain a central venous pressure of 12 mm Hg. Flow cytometry was used for determination of microvesicles before induction of sepsis (baseline) and after 8 h. Platelets and microvesicles were identified with an anti-platelet monoclonal Ab and a secondary antibody. Microvesicles were determined as the smallest 1-3% positive cells in forward scatter. Intergroup comparisons were performed using Wilks-Lambda and Ryan-Einot-Gabriel-Welsh F-test. Differences within groups were compared using a two-tailed Student's t-test. RESULTS: Baseline values were considered as 100%. While microvesicle formation was reduced in HES (73 (sd 19)%), MFG4% (63 (41)%) and MFG8% groups (53 (17)%), an increase in the RS-group (210 (121)%) was observed. Eight hours after induction of sepsis, formation of microvesicles was significantly higher in the RS group compared to all colloid-treated groups. CONCLUSION: In this porcine septic shock model the formation of platelet-derived microvesicles was significantly increased by volume replacement with Ringer's solution in comparison to colloid solutions.

Effects of oxypolygelatin and dextran 70 on hemostatic variables in dogs.

OBJECTIVE: To evaluate and compare coagulation variables following the administration of oxypolygelatin and dextran 70 to clinically healthy dogs. STUDY DESIGN: Randomized cross-over experimental study. ANIMALS: A total of eight healthy adult female Beagles aged 2-4 years old and weighing 11.8 +/- 2.7 kg. METHODS: The dogs received a 15-minute intravenous (IV) infusion of 5 mL kg-1 oxypolygelatin or 10 mL kg-1 6% dextran 70. Before (PRE) and at 2, 5, and 24 hours after administration, packed cell volume (PCV), total solids concentration (TS), prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen concentration (FIB), platelet numbers (Plat), factor VIII coagulant activity (VIII:C), von Willebrand factor antigen concentration (vWf:Ag) and platelet function and buccal mucosal bleeding time (BMBT) were measured. Platelet function was assessed using aggregation and by measuring ATP release from aggregating platelets over 6 minutes, with 20, 10, and 5 micro m ADP and 5 and 10 micro g of collagen mL-1 as platelet activation agonists. RESULTS: All baseline values were within our normal ranges, except for one dog that had low vWf:Ag PRE values prior to both dextran and oxypolygelatin administration. Following dextran and oxypolygelatin administration, the PCV and TP were significantly (p < 0.05) decreased. Plat, FIB, and vWf:Ag decreased, while BMBT and VIII:C increased following dextran administration. Dextran also caused a significant decrease in platelet aggregation in response to ADP. Oxypolygelatin caused a significant decrease in vWf:Ag, Plat, and FIB compared to PRE values. The total amount of ATP released, standardized to platelet number, did not vary significantly for either group at any sampling time from PRE values. No significant changes from PRE values were noted at any time in either group for PT or APTT. CONCLUSION: At the doses administered, both dextran and oxypolygelatin can interfere with hemostatic variables in healthy dogs, but dextran's effect is more profound and prolonged when compared to oxypolygelatin. CLINICAL RELEVANCE: Oxypolygelatin causes fewer hemostatic abnormalities when compared to dextran, making it a superior colloid for administration at the doses tested.

Successful endovascular treatment of a spinal dural arteriovenous fistula with trisacryl gelatin microspheres.

We report on the endovascular treatment of a spinal dural arteriovenous fistula (SDAVF) in a 50-year-old man, who presented with rapidly progressive paraparesis of lower extremities. Standard treatment of SDAVFs is by either embolization with liquid adhesive agents like NBCA or microsurgery. In our case the fistula was successfully occluded by application of trisacryl gelatin microspheres (TGM). Due to a small size of the feeding intercostal artery a superselective catheterization of the fistula itself by a microcatheter could not be performed. The particles were hence delivered through a diagnostic spinal catheter positioned within the proximal part of the feeding intercostal artery. Control MRI five weeks after intervention showed normalized perimedullary veins, which were dilated and tortuous initially. It also displayed a clinically silent focal ischaemia within the spongiosa of an adjacent hemi-vertebra due to particle passage through intersegmental vascular collaterals. A control angiogram confirmed the disappearance of the fistula. The patient underwent physiotherapy and experienced significant improvement of his gait within three months after intervention.

[Contrast medium echocardiography-assisted pericardial drainage]. / Kontrastmittelechokardiographisch gesteuerte Perikarddrainage.

The most effective treatment for pericardial effusion and cardiac tamponade is removal of the pericardial fluid. Surgical pericardiotomy is associated with high mortality and morbidity. Similarly, subcostal percutaneous blind pericardiocentesis was reported to have unacceptably high mortality and complication rates. Major complications associated with blind needle punctures are right heart penetration, hemopericardium, puncture of the coronary arteries, liver and lung bleeding. Even under fluoroscopic guidance and electrocardiographic needle monitoring high complication rates persist. Pericardial drainage has been often inadequate, with frequent recurrences of significant pericardial effusions. Two-dimensional echocardiographically guided pericardiocentesis is reported to improve efficacy and safety of percutaneous puncture. Moreover, it allows immediate verification of the procedural success. We evaluated the efficacy and safety of an echocardiographically guided contrast agent controlled pericardiocentesis. This is a retrospective, descriptive study on 126 consecutive patients who underwent percutaneous pericardiocentesis at the University Hospital Essen, Germany, from 1995 to June 2000. There were 51 women (41%) and 75 men (55%) with a mean age of 52 +/- 14 years. Standard techniques for quantification of pericardial effusion were used. Depending on the localization of the pericardial effusion an apical or subxiphoidal approach was chosen. The puncture was performed under echocardiographic guidance and the position of the needle was controlled by injection of contrast agent. Over a long guidewire a pigtail catheter was inserted through a sheath for further drainage of pericardial fluid. The catheter was removed after a maximum of 48 hours to avoid infection of the pericardial cavity. An apical approach was chosen in 98 patients (78%), a subcostal in 28 patients (22%). The procedure was successful in 99% of the attempts. No death or clinical complication occurred. The maximal pericardial diameter measured by two-dimensional echocardiography was 32 +/- 16 mm before and 5.3 +/- 2 mm after drainage. The calculated pericardial effusion was 657 +/- 342 ml. A fluid volume of 605 +/- 342 ml could be drained. In all patients a pericardial catheter was placed for 1.4 +/- 0.8 days. Recurrence of pericardial effusion occurred in 18 patients (14%). Of these, 15 patients underwent repeated successful pericardiocentesis (2.5 +/- 0.8), and 3 patients were referred to surgical pericardiotomy. Pericardiocentesis under echocardiographic contrast agent guidance is a safe, successful and cost effective procedure for diagnostic and therapeutic drainage of pericardial effusion. Two-dimensional echocardiography allows localization of the optimal puncture site as well as the quantification of the effusion depth. The injection of contrast agents into the pericardial cavity improves the safety and accuracy of the procedure. Even recurrent pericardial effusions can be treated successfully.

Pharmacokinetics of oxypolygelatine in healthy volunteers.

OBJECTIVE/METHODS: The pharmacokinetics of the plasma substitute oxypolygelatine (OPG) were studied in 12 healthy volunteers after single-dose administration of 27 ml x kg(-1) body weight, with a maximum of 2000 ml. OPG was determined in plasma and urine over 48 h after the infusion. Peak plasma OPG concentrations at the end of the infusion were determined to 4.600 (623) microg x ml(-1), the area under the plasma concentration/time curve (AUC(0-infinity)) was calculated to 70.135 (15.861) microg x h x ml(-1). RESULTS: The model-independently calculated volume of distribution came to 23.1 (4.8) 1 with a clearance total is (Cl(tot)) of 24.6 (6.8) ml x min(-1). The initial half-life according to a three-compartment model came to 0.3 (0.2) h, followed by a distribution half-life of 3.1 (2.6) h and a terminal elimination half-life of 13.4 (2.2) h. Cumulative urinary excretion of OPG was 64% after 48 h. CONCLUSION: This low recovery rate may be explained by the distribution of OPG into the extravascular space and subsequent degradation in tissue sites.

Simplified endoproteinase assays using gelatin or azogelatin.

Endoproteinase assays with gels containing incorporated gelatin have shown that gelatin is an exceptional substrate for studying enzymes from different sources. However, due to its solubility in trichloroacetic acid, gelatin is not suited to "in-solution" assays carried out in the classic manner (by reading the absorbance of supernatants of hydrolysis reactions after the substrate has been precipitated with trichloroacetic acid). In this paper we demonstrate that gelatin can be used for such analyses by using isopropanol as precipitating reagent. Alternatively, azogelatin, which is precipitated by trichloroacetic acid, can be used. Azogelatin also serves as a very good substrate. One problem with using gelatin (or any nonderivatized protein) as substrate for measuring the activity of crude enzyme preparations is that protein contaminants in the enzyme preparation are hydrolyzed. The resulting peptides are impossible to differentiate from those released from the gelatin substrate. This problem is obviated when azogelatin is used, since its peptides are detected at 440 nm, where nonderivatized peptides do not absorb. Unlike some azo-derivatized proteins, azogelatin is soluble from pH 3.0 to 9.0. This, together with the fact that it is hydrolyzed by many different endoproteinases, makes it suitable for many applications.

Optimized transcranial Doppler technique for the diagnosis of cardiac right-to-left shunts.

Transcranial Doppler sonography (TCD) is a simple method to detect a right-to-left cardiac shunt, although standardized procedures do not exist. In this study 69 patients were tested according to predetermined criteria and procedures (cluster of > 10 microbubbles, duration between injection in the cubital vein and detection in the middle cerebral artery [MCA] < or = 10 sec). Agitated saline solution was compared to oxypolygelatine, a plasma volume expander, as contrast media. Valsalva's maneuver and coughing were used to provoke right-to-left cardiac shunting, detected by TCD, transthoracic echocardiography (TTE), and transesophageal echocardiography (TEE). Oxypolygelatine caused a significantly higher number of microbubbles in the right atrium and MCA than did the saline solution, leading to a greater diagnostic reliability of TCD (paired t test, p < 0.001). Coughing did not provoke right-to-left cardiac shunts (x2 analysis, p < 0.001). The technique used for carrying out Valsalva's maneuver was important for the detection of right-to-left cardiac shunts. Twenty-five right-to-left shunts were diagnosed with TCD and 18 with TTE (36 vs 26%; x2 analysis, p = 0.1). The findings indicate that TCD when properly done is highly sensitive and specific for the diagnosis of right-to-left cardiac shunts.

Volume replacement with gelatin or hydroxyethylstarch solutions does not impair somatosensory evoked potential monitoring: a haemodilution study in conscious volunteers.

The influence of haemodilution with colloids on somatosensory evoked potentials in non-premedicated volunteers is reported. In seven volunteers (randomized crossover design), blood (20 mL kg-1 within 30 min) was removed and simultaneously replaced by gelatin 3% or hydroxyethylstarch 6%. After 30 min, blood was retransfused within 30 min. Median and posterior tibial nerve somatosensory evoked potentials were recorded from the cortex, second cervical vertebra, Erb's point and 1st lumbar vertebra, respectively. One volunteer experienced a severe allergic reaction to gelatin, therefore only six gelatin trials were evaluated. Haemodilution decreased the haematocrit from 39.8 +/- 1.6% (mean +/- SD) to 31.1 +/- 2.0% (gelatin) and from 40.7 +/- 1.7% to 29.8 +/- 1.5 % (hydroxyethylstarch), respectively. Retransfusion increased haematocrit to 34.4 +/- 0.9% (gelatin) and to 34.2 +/- 1.3% (hydroxyethylstarch). Neither haemodilution with gelatin nor haemodilution with hydroxyethylstarch or retransfusion influenced evoked potentials. In conclusion, the treatment of blood loss up to 30% of estimated blood volume with gelatin or hydroxyethylstarch will not affect somatosensory evoked potential monitoring provided normovolaemic conditions are maintained.

Benefits of blood cell transplant cryopreservation with oxypolygelatine (Gelifundol) plasma substitute.

In two groups of 11 patients with poor prognosis malignancies undergoing high-dose sequential chemotherapy, we have evaluated the cryopreservation of blood cell transplants with oxypolygelatine-containing (55% oxypolygelatine, 6% hydroxyethylstarch, 5% dimethyl sulfoxide) vs standard human serum-containing (55% human serum, 6% hydroxyethylstarch, 5% dimethyl sulfoxide) cryoprotectant mixtures. Evidence is presented demonstrating that substitution of human serum proteins with oxypolygelatine has no detrimental effect either in vitro on the post-thawing recovery of hematopoietic progenitors or in vivo on the capacity of marrow reconstituting function in patients treated with myeloablative cancer therapy and autologous blood cell transplant. Oxypolygelatine is commercially available for clinical use as a plasma expander, is 30-fold less expensive than human serum albumin, is certified free of foreign serum proteins and antibodies as well as free of pyrogen, viral, mycoplasmal and bovine spongiform encephalopathy contaminants. Because of these characteristics, oxypolygelatine permits avoidance of: (1) the use of expensive serum albumin; (2) the fastidious preparation of autologous plasma or serum, and (3) the risk of infection associated with the infusion of allogeneic serum. Because of these practical advantages, we recommend the clinical use of oxypolygelatine as a substitute for human serum proteins for the routine cryopreservation of blood cell transplants.

Evaluation studies on oxypolygelatin and degraded gelatin as plasma volume expanders.

Oxypolygelatin (CAS 9005-91-8, OPG) and degraded gelatin (CAS 9000-70-8, DG) have attracted the interest of many investigators as promising plasma protein substitutes. This paper deals with comparative evaluation studies on OPG and DG as regards stability and some biochemical consequences following i.v. infusions in rabbits. Accelerated aging tests showed a decrease in pH of OPG from 7.3 to 7.0. The pH of DG increased from 5.2 to 5.4 during the same period of aging. In both cases, the buffer capacity increased 3.0 to 3.5 in case of OPG and from 2.5 to 3.7 in case of DG. The relative viscosity of OPG decreased from 2.18 to 1.98 as compared to 1.79 to 1.58 in case of DG. Comparative studies on both OPG and DG postinfusion in rabbits, showed significant (p < 0.001) retention OPG in blood 24 h postinfusion, at which time, DG was practically absent. The decline in rabbit plasma protein was marked and more persistent in case of compared to DG. Plasma sodium showed a significant decline (p < 0.05) in case of OPG 1 h postinfusion, while plasma potassium showed a significant decline (p < 0.05) immediately postinfusion. In case of OPG, serum calcium showed a significant decline (p < 0.001) immediately postinfusion. This effect was marked at 1 h, 5 h and 24 h postinfusion. In case of DG, no significant changes in the levels of sodium, potassium, calcium and magnesium were observed at all time intervals postinfusion of the plasma volume expander.

Identification of patent foramen ovale permitting paradoxic embolism.

OBJECTIVES: We sought to analyze the morphologic and functional characteristics of the patent foramen ovale in patients with different clinical likelihoods for paradoxic embolism. BACKGROUND: The incidence of patent foramen ovale is increased in patients with otherwise unexplained arterial ischemic events. Because signs of venous thrombosis are absent in most patients, the diagnosis of paradoxic embolism is often questioned, even when patent foramen ovale is the only potential explanation for the ischemic event. METHODS: Seventy-eight patients with a patent foramen ovale detected by contrast transesophageal echocardiography were studied: 21 patients with an otherwise unexplained arterial ischemic event and clinical evidence implying paradoxic embolism (group I), 30 patients with an unexplained ischemic event but no clinical evidence for paradoxic embolism (group II) and 27 patients without an ischemic event (group III). RESULTS: During transesophageal contrast echocardiography, patients in group I had more severe right to left shunting (mean +/- SD 52 +/- 16% of the left atrial area filled with contrast medium) and a wider opening of the patent foramen ovale (7.1 +/- 3.6-mm separation between the septum primum and the septum secundum) than did patients in group II (35 +/- 15% and 4.4 +/- 3.2 mm, respectively, p < 0.001) or group III (23 +/- 12% and 3.0 +/- 2.0 mm, respectively, p < 0.001). The incidence of atrial septal aneurysm was similar in the three groups. Severe contrast shunting (> or = 50% of the left atrial area filled with contrast medium) and wide opening of the patent foramen ovale (> or = 5-mm separation) revealed a high sensitivity (71% and 86%, respectively) and high specificity (86% and 96%, respectively) for identification of group I patients. CONCLUSIONS: Right to left contrast shunting is more severe and opening of the patent foramen ovale is larger in patients with ischemic arterial events considered to be due to paradoxic embolism. In patients with a patent foramen ovale as the only potential cause for ischemic events and no signs of venous thrombosis, morphologic and functional variables assessed by transesophageal echocardiography may be helpful in estimating the likelihood of paradoxic embolism.

[In vitro modification of plasma viscosity and erythrocyte aggregation by four plasma substitutes]. / Zur In-vitro-Beeinflussung von Plasmaviskosität und Erythrozytenaggregation durch vier Plasmaersatzmittel.

We tested the haemorheological effects of the addition of 3.5% oxypolygelatine, 10% dextran 40, 6% dextran 75 or 5% albumin, respectively, to fresh donor blood of 25 healthy young persons. We examined the aggregation and the viscosity of substituent plasma mixtures in such various, but constant volume relations as may be present during intravenous infusion. Albumin reduced viscosity and aggregation, but especially dextran 75 increased both parameters significantly.

[Hemorheologic effects of hydroxyethyl starch 200/0.5, dextran 40, oxypolygelatine and full electrolyte solution over 48 hours]. / Hämorheologische Wirkungen von Hydroxyäthylstärke 200/0.5, Dextran 40, Oxypolygelatine und Vollelektrolytlösung über 48 Stunden.

Four patient groups (n = 28 patients) received in a randomised clinical trial a single intravenous infusion of 500 ml of 10% dextran 40, 3.5% oxypolygelatine, 6% hydroxyethyl starch 200/0.5 or saline solution, respectively. The haemorheological parameters haematocrit, plasma viscosity and erythrocyte aggregation were followed up during 48 hours. In our study oxypolygelatine showed better rheological results than HAES 200/0.5. Dextran 40 especially increased the plasma viscosity and erythrocyte aggregation, so that we cannot recommend this plasma substituent for hypervolemic haemodilution.

Detection of left-to-right shunt in atrial septal defect by negative contrast echocardiography: a comparison of transthoracic and transesophageal approach.

The occurrence of a right atrial negative contrast effect as an indicator of left-to-right shunt was studied in 101 patients with atrial septal defect by peripheral venous contrast injection during transthoracic and transesophageal echocardiography. Confirmation of the diagnosis was provided by cardiac catheterization or by autopsy in 72 (72%) patients. The defect could be visualized directly in 57 (57%) patients during the transthoracic and in 93 (93%) during the transesophageal examination (p < 0.001). A negative right atrial echo contrast effect was observed in 53 of 92 (58%) patients from the transthoracic and in 86 of 92 (93%) patients from the transesophageal approach (p < 0.001). Among these were seven (7%) patients with an aneurysmal interatrial septum but no directly visible defect during conventional transesophageal imaging. Appearance of contrast in the left atrium indicating right-to-left shunting was seen in 70 of 92 (76%) patients from the transthoracic and in 91 of 92 (99%) patients from the transesophageal approach (p < 0.001). Contrast injection during transesophageal imaging also helped identify additional malformations in 12 (12%) patients. Thus transesophageal echocardiography with echo contrast injection is a very reliable diagnostic method in patients with suspected atrial septal defect.