Einfluss von niedrigem Alkalimetallgehalt im Atemkalk auf Compound-A-Bildung w?hrend Low-flow-Narkosen mit Sevofluran

Nach bisherigem Kenntnisstand ist der Gehalt an Alkalimetallhydroxiden in Atemkalken wesentlich für die Bildung von Compound A (CpA) aus Sevofluran (Sevo) verantwortlich. Insbesondere das Kaliumhydroxid (KOH), weniger das Natriumhydroxid (NaOH), reagiert im Laborversuch stark mit Sevofluran. Mit dieser klinischen Studie sollte untersucht werden, ob die Verwendung eines KOH-freien Atemkalks w?hrend Niedrigflussnarkosen (0,8 l/min Frischgasfluss) mit Sevofluran bei laparoskopischen Cholezystektomien tats?chlich zu einer Verminderung der CpA-Exposition führt. In die Studie wurden 30 Patienten eingeschlossen. Bei jeweils 15 Patienten wurde entweder Sodasorb (SO) oder KOH-freier Soda Lime (SL) verwendet. Von der SO-Gruppe mussten 3 Patienten auf Grund von technischen Problemen bei der CpA-Messung ausgeschlossen werden. Neben demographischen Daten wurden Vital- und Beatmungsparameter sowie die Konzentrationen von Sevofluran und Kohlendioxid dokumentiert. Die durchschnittlichen endtidalen Sevoflurankonzentrationen betrugen 1,94±0,17 (SO) bzw. 1,97±0,15 (SL) Vol.-%, die Gesamtexposition gegenüber Sevofluran 1,52±0,36 (SO) und 1,64±0,47 (SL) MAC-h (n. s.). Die maximale inspiratorische CpA-Konzentration war in der SL-Gruppe signifikant h?her (19,6±2,8 vs. 11,7±4,1 ppm, p<0,001). Der alleinige Verzicht auf KOH in NaOH-haltigen Atemkalken führt daher nicht zwangsl?ufig zu einer Verminderung von CpA.     

The detection and use of hemoglobin mutants in the direct analysis of human globin genes

Many human globin-chain mutants contain amino acid replacements that result from single base changes in the corresponding globin gene. Using recombinants, the coding sequences of each of the alpha-, beta-, Ggamma- , and Agamma-globin genes have now been determined. Those sequences of DNA that are cleaved by a number of specific restriction endonucleases have been identified and accurately positioned. Mutations at these sequences abolish the restriction site, and therefore, the pattern of DNA fragments containing hybridizing globin-gene sequences is altered compared to DNA from normal persons. This allows the identification of one of a pair of cross-hybridizing human globin-gene sequences, as is shown here for the two alpha-globin, the two gamma-globin, and the delta- and beta-globin genes.     

Human parvovirus B19-induced epidemic acute red cell aplasia in patients with hereditary hemolytic anemia

From March to August 1984, 26 patients with hereditary hemolytic anemia in northeastern Ohio developed acute, profound red cell aplasia. The patients included 14 males and 12 females 2 to 23 years old, with sickle cell anemia (20 cases), hemoglobin SC-disease (4 cases), sickle- beta-thalassemia (1 case), or hereditary spherocytosis (1 case). All had an acute onset of severe reticulocytopenia and anemia and prodromal symptoms of illness including fever, abdominal symptoms, headache, and arthralgias. Twenty-two received transfusions. Reticulocytosis occurred spontaneously within 2 to 14 days of presentation. In five acute-phase sera, 10(8) to 10(12) viral particles/mL were detected by electron microscopy. Human parvovirus B19 DNA was demonstrated in high concentration by hybridization in the same five acute-phase sera and in low concentration in sera of eight additional patients. The five highly viremic sera inhibited erythroid colony formation in vitro. B19- specific IgM was detected in sera of 24/26 patients, and B19-specific IgG in 21 of 22 patients tested. Our results indicate that human parvovirus B19 was the etiologic agent in this large epidemic of life- threatening acute red cell aplasia in patients with hereditary hemolytic anemia.     

Deficiency of platelet membrane glycoprotein Ia associated with a decreased platelet adhesion to subendothelium: a defect in platelet spreading

A bleeding disorder with absent collagen-induced platelet aggregation and adhesion has been described in a patient whose platelets failed to express surface glycoprotein Ia. We studied the interaction of her platelets with subendothelium in an annular perfusion chamber and the interaction with purified human collagen type III in a rectangular perfusion system under flow conditions. Platelet adherence was almost completely absent both at low and high shear rates. The few platelets which adhered remained in the contact stage without subsequent spreading and aggregate formation. Addition of a monoclonal antibody, which was directed against the von Willebrand moiety of FVIII-VWF, to the blood, completely abolished platelet adherence at high shear rates and had a partial effect at low shear rates. These data indicate that von Willebrand factor plays a role in the initial attachment (contact stage) of platelets to subendothelium. We conclude that the bleeding disorder and excessively prolonged bleeding time in our patient are caused by a new specific defect of the platelet-vessel wall interaction.     

Superparamagnetic iron oxide: enhanced detection of focal splenic tumors with MR imaging

Superparamagnetic iron oxide (AMI-25), a reticuloendothelial cell-specific contrast agent for magnetic resonance (MR) imaging, was evaluated for its ability to permit detection of splenic metastases in 18 patients. Superparamagnetic iron oxide, at a dose of 30 mumol of iron per kilogram, decreased the signal intensity of spleen from 19.5 +/- 4.8 to 3.1 +/- 2.2 (spin-echo sequence, repetition time msec/echo time msec = 1,500/42; P less than .05), without changing the signal intensity of tumor. As a result, the tumor-spleen contrast-to-noise ratio increased from 0.2 (tumor isointense relative to spleen) to 18.0 (tumor hyperintense relative to spleen). As a consequence of increased contrast, splenic tumors were detected in four of 18 patients (45 individual lesions; P less than .05), whereas nonenhanced MR imaging permitted detection of splenic lesions in only two of 18 patients (four individual lesions). Maximum tumor-spleen contrast was achieved within 60 minutes after intravenous administration. These initial clinical results indicate that MR imaging with superparamagnetic iron oxide may offer improved accuracy in the diagnosis of splenic tumors.