Biomedical subjects
Publications and source records attributed to K G Schmidt.
In 2 cases of idiopathic thrombocytopenic purpura a transient increase in platelet count was observed during and following infectious episodes. This association which is in contrast to the previously reported aggravating effect of infection on immune thrombocytopenia may be of rather frequent occurrence, being overlooked, however, because of lack of relevant clinical manifestations.
Because of the central role of blood platelets in haemostasis, 111In-labelled platelets might be supposed to participate in the haemostatic process and give rise to scintigraphic hot spots at the bleeding sites in cases of intermittent gastrointestinal haemorrhage. Three patients with intermittent gastrointestinal haemorrhage are described in whom focal tracer accumulations after injection of autologous 111In-labelled platelets indicated the presence of transient gastrointestinal haemorrhage. Repeatedly performed scintigraphy after injection of 111In-labelled platelets may prove to be a useful tool for the localization of intermittent gastrointestinal haemorrhage.
The function of 111In-labelled platelets has been assessed by collagen-induced aggregation of platelets in samples of whole blood. The blood samples were drawn after injection of autologous 111In-labelled platelets in 19 subjects undergoing platelet kinetic studies. It was thus possible to measure the aggregability of labelled and unmanipulated platelets simultaneously. 111In-labelled platelets aggregated to the same extent as unmanipulated platelets when tested from 10 min to 24 h after injection of the labelled platelets. The results confirm the assumption that minimal damage is inflicted on the platelets during the isolation and labelling procedures, and support the concept that platelets manipulated in vitro may recover in vivo within a few minutes after reinjection.
111In-labelled human platelets were aggregated with ADP and subjected to ultrastructural morphometric analysis. In addition, the hemostatic function in vivo and the ultrastructural morphology ex vivo of rabbit platelets were examined. The platelet isolation and labelling procedures exerted no certain influence on the aggregation response, and platelet surface/volume calculations did not indicate that platelet activation had taken place. Bleeding time experiments in rabbits indicated that the hemostatic effectiveness of the labelled platelets was unimpaired. Transfused 111In-labelled platelets isolated from the recipient rabbits exhibited fewer electromicroscopic signs of platelet activation than the same platelets prior to transfusion. Our results indicate that the described procedure for isolation and 111In-labelling of platelets induces only insignificant damage to the platelets.
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A simple method for preparation of platelet suspensions from whole blood in buffer is described. The platelets and a fraction of the erythrocytes are processed simultaneously, whereby the erythrocytes serve as a supporting cushion in the centrifugation steps. Using this earlier described principle of platelet separation, platelet yields of 90--100% from whole blood could be achieved. Investigations of platelet aggregation and platelet morphology indicate that this method of separation is gentle. By obviating the selection of certain platelet populations this may facilitate the interpretation of the results of in vitro and in vivo platelet-function studies.
Platelets suspended in buffer were labelled with 111Indium-xoine. In the isolation procedure the platelets and a fraction of the erythrocytes are processed simultaneously, whereby the erythrocytes serve as a supporting cushion in the centrifugation steps. Various factors which influence the labelling effectiveness were examined, and the method's utility was estimated by in vivo studies in rabbits. A platelet concentration of more than 800 x 10(9)/1 and an oxine concentration of approximately 6 micrograms/ml in a plasma-poor system (transfer of platelets from plasma to buffer without further washing steps) will yield a high labelling efficiency. If the platelet isolation yield is to be large, a slight erythrocyte-leucocyte contamination must be accepted. Our experimental results indicated that this is permissible. In vivo investigations of 5 rabbits showed in vivo recoveries of platelets from 61--74% and mean survival times from 69 h to 110 h. This supports the assessment that the method of platelet isolation and labelling is gentle.
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In 51 untreated cases of ulcerative colitis and Crohn's disease some cellular (neutrophil alkaline phosphatase activity, neutrophil NBT reducing capacity, and neutrophil and plasma lysozyme activities) and humoral (serum orosomucoid and serum haptoglobin) indices of disease activity were quantitated. The most pronounced signs of disease activity, thus, were found in severe cases of ulcerative colitis. Combining lysozyme activities with other disease activity indices seems to facilitate the distinction between severe cases of Crohn's disease and ulcerative colitis. Beyond this the addition of the humoral indices seemed not to offer substantial help.
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The concentration of lysozyme in plasma (P) and in neutrophil leucocytes (N) was determined by a turbidimetric method in 32 patients with ulcerative colitis (U.C.), 11 patients with Crohn's disease (C.D.), 9 patients with haemorrhagic proctitis, and 39 healthy volunteers. In active U.C., P was significantly elevated (p less than 0.05), whereas C.D. showed normal values. Corresponding N was significantly reduced in active U.C. (p less than 0.05) but normal in C.D. In calculating the ratio N/P, highly significant lower values were found in active U.C. (p less than 0.001) compared to normal levels in C.D. The high P in active U.C. is presumed to reflect an accelerated destruction of neutrophil leucocytes as well as an intensified turnover rate. The reduced N is probably attributable to an inhibited synthesis. The findings suggest that lysozyme determinations are valuable in be differential diagnosis of active U.C. and C.D.
The carcinogenic action of the hydrocarbon mixture predominantly found in condensates of automobile exhaust gas can be attributed almost exclusively, on the basis of the results presented here, to a group of substances (PAH) with an insignificant weight proportion. It was not possible to demonstrate an inhibitory action of most of the weak-to-inactive hydrocarbons; on the contrary, an additive effect of the two types could be observed. At very high doses (almost 10 times higher than the highest doses selected in the rest of the trial) the group of substances which were supposed to be non-carcinogenic also proved to be biologically effective. Subsequent individual studies on the same animal strain should clarify whether this action is to be attributed to one or two representatives of this group, e.g., benzo[e]pyrene or chrysene.
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A mixture of 11 carcinogenic and noncarcinogenic hydrocarbons was applied to the shorn skin of the back of 3400 female NMRI-mice. The proportion of the hydrocarbons in the mixture corresponded to the analytical findings in condensates of cigarette smoke, automobil exhaust gas, and preservation curing smoke and tar. Antagonistic effects by the individual hydrocarbons in the mixture were not observed, on the contrary the substances in the mixture showed additive effects. There were no differences in the mode of action of the different mixtures.