Biomedical subjects
Publications and source records attributed to J Kiem.
The activity of the selenoenzyme glutathione peroxidase (EC 1.11.1.9) was determined in platelets of 15 patients with acute myocardial infarction and 13 control subjects. The platelets of the patients had significantly lower activities of the enzyme (P(t) greater than 0.99). This may be related to the pathogenesis of the disease.
The differences in concentrations of cesium, cobalt, iron, mercury, rubidium, selenium and zinc between serum and plasma were examined with the aid of instrumental neutron activation analysis. Eighty serum and plasma samples obtained from 13 donors were compared. Serum was prepared in plastic tubes immediately after clotting, and plasma was separated with heparin as anticoagulant. No significant differences in the concentrations of cesium, cobalt, mercury and selenium were observed. However, the concentrations of iron, rubidium and zinc were significantly higher in serum than in plasma. The average differences were 322, 12 and 20 ng/ml for iron rubidium and zinc, respectively. The average differences found for cesium, rubidium and zinc were far below that which can be expected from a complete, or considerable release of these elements from platelets which aggregate or disintegrate during the clotting process in preparing serum.
Sampling of platelets for trace-element analysis poses special problems: obtaining adequate sample material, achieving a sufficient cell purity, preserving viability (integrity), correcting for trapped plasma, and controlling contamination. We used a blood-cell separator for the primary isolation of platelets from blood, and differential centrifugation in natural plasma to further isolate them. The pyrimidopyrimidine RA233 was used as a stabilizer to maintain viability. 131I-labeled human serum albumin was used to estimate trapped plasma. Contamination was controlled by using five-times-distilled water to simulate donor's blood in the system and by comparing three fractions: the serum, the first portion of the platelet-rich plasma, and the supernatant plasma after the final centrifugation. Neutron activation analysis was used for the elemental analysis. A single differential centrifugation of the platelet-rich plasma from the blood-cell separator at 400 x g for 8 min was optimum (mean mass fractions:erythrocytes/platelets less than 5 mg/g and leukocytes/platelets less than 20 mg/g). The trapped plasma in the wet platelet samples amounted to about 0.40 g/g. No appreciable contamination from the sampling system was found for the elements Ag, Cd, Co, Cr, Cs, Cu, Fe, Mo, Rb, Sb, Se, and Zn.
We determined the elements Cu, Fe, K, and Zn in normal human platelets by neutron activation analysis. The platelets were obtained from seven donors and treated as described in Part I. The elemental composition is expressed on a wet-weight basis for plasma-free platelets. The following results were obtained (+/- values are 1 SD); "Pure" platelets: trapped plasma = 378 +/- 35 mg/g, water content = 715 +/- 15 mg/g, mean weight of the single platelet (by two different methods) = 9.9 +/- 1.1 pg and 11.2 +/- 1.7 pg, K = 4.39 +/- 1.06 mg/g, Zn = 49.23 +/- 10.97 microgram/g, Fe = 12.28 +/- 2.94 microgram/g, and Cu = 1.39 +/- 0.25 microgram/g. "Impure" platelets: trapped plasma = 349 +/- 31 mg/g, water content = 736 +/- 12 mg/g, K = 3.26 +/- 0.78 mg/g, Zn = 35.71 +/- 7.99 microgram/g, Fe = 17.11 +/- 5.10 microgram/g, and Cu = 1.39 +/- 0.21 microgram/g. To our knowledge, no data on Fe and Cu in platelets have hitherto been reported.
The elements Ag, Au, Cd, Co, Cr, Cs, Mo, Rb, Sb, and Se were determined in platelets from seven normal donors. The results, in ng/g wet weight, for plasma-free platelets follow: "Pure" platelets: Ag = 29 +/- (18), au = 0.22 +/- (0.22), Cd = 6.2 +/- 3.4, Cs = 54.8 +/- 19.2, Cr = 6.1 +/- 2.5, Co = 7.5 +/- (5.0), Mo = 3.4 +/- 1.3, Rb = 10400 +/- 3000, Sb = 18 +/- (26), and Se = 782 +/- 127. "Impure" platelets: Au = 0.23 +/- (0.28), Cd = 6.4 +/- 2.6, Cs = 35.2 +/- 13.8, Cr = 8.2 +/- 2.9, Co = 2.9 +/- (3.0), Mo = 3.2 +/- 0.8, Rb = 8700 +/- 1700, Sb = 13.2 +/- (8.7), and Se = 679 +/- 57. To our knowledge, none of these 10 trace elements has been determined in platelets before. The selenium concentration in platelets exceeds that in other tissues (e.g., liver). We suggest that glutathione peroxidase or other unknown selenoenzymes are particularly important in platelet metabolism. Platelets are crucial for triggering thrombosis, and so may be involved as links between selenium deficiency and the concomitant increased death rate from cardiovascular disease.
In 7 rabbits the drainage from the subconjunctival space to the cervical lymph nodes was observed after subconjunctival injection of 99mTc-micro-colloid. Measurements of the activity distribution were made in vivo with an Anger type camera (pho-Gamma-IV Hp, Searle Nuclear Chicago) and in vitro after dissection with a sodium iodine crystal well counter (Clinimat-200, Picker). 6 hours after the injection into the subconjunctival space of the right eye an average of 53.7% of the applied activity had drained off. A significant accumulation of activity could constantly be registrated in the cervical lymph nodes. Its amount was generally up to 2.08% of the applied total activity per animal, with a large individual spreading. In detail, activity was found in all 7 cases in the right superficial cervical lymph node, in 5 cases moreover in the right mandibular lymph node, additionally in 2 animals in the right or left deep cervical lymph node respectively and in one animal as well in the right as in the left deep cervical lymph node. Besides, in all cases high activity was registered in the right retrobulbar and subconjunctival spaces just as in the right eye. A small activity in the right optic nerve could be pointed out in three of our seven cases.
In order to investigate lymph drainage from the retrobulbar space colloid solutions (198Au-colloid and 99mTc-sulfur-colloid) were injected into the right retrobulbar space of 31 rabbits. The distribution of radioactivity was measured in vitro after dissection with a sodium iodine crystal well counter and in some animals in vivo with the Gamma camera. More than 90% of the applied activity of either colloid solution was found in some animals up to the eighth day post injection in the retrobulbar space and in the liver. The remaining activity was recovered mainly from the regional lymph nodes, due to its smaller particle size higher values were registered in the experiments with 198Au than in those with 99mTc. The highest concentrations with up to 4,6% of the activity were observed in the deep cervical lymph nodes on both sides. Minor concentrations of activity were found ipsilateral in the superficial cervical and mandibular lymph nodes. Furthermore, small but significant activities were demonstrated in the optic nerves as well as in the contralateral retrobulbar space. The present data clearly substantiate the existence of lymph drainage, although a slow one, from the retrobulbar space. Moreover they indicate a reverse prelymphatic-lymphatic flow toward the optic nerves and the contralateral retrobulbar space. These results are of importance in the discussions of lymphostatic ophthalmopathy. The clinical application of this method is desirable; however, at present it is not yet practicable without further studies.
For the investigation on the lymph drainage from the orbita 99mTc-microcolloid, 99mTc-albumin and 198Au-colloid have been injected into the retrobulbar space of 24 rabbits. Measurements of the activity's distribution have been made in vivo with an Anger type camera (pho-Gamma-IV Hp, Searle Nuclear Chicago) and in vitro after section with a sodium iodine crystal well counter (Clinimat-200, Picker). A significant concentration of the activity could be observed for the most part in the equilateral Lymphonoduli cervicales profundi and superficiales and for the less part also in the equilateral Lymphonoduli mandibulares and contralateral Lymphonoduli cervicales profoundi. Furthermore significant activities could be pointed out in the optic nerves as well as in the contralateral retrobulbar space. The data substantiate a lymph drainage from the orbita as well as a partly reverse "prelymphatic-lymphatic" flow and are of importance for discussions about lymphostatic ophthalmopathy and sympathetic ophthalmitis. For application on man 99mTc-microcolloid (Lymphoscint) shoud be preferred, because with this tracer 1. the lymph drainage can be measured quantitatively quite exactly by extern measurement with the Anger-camera, 2. the allowable radiation dosis for the lens is lying between 0.5-1.0 rad/mCi.
In order to study lymph drainage from the eye colloid solutions (198Au-colloid and 99mTc-sulfur-colloid) were injected into the right anterior chamber of the eye in 12 rabbits. The distribution of the radioactivity was measured in vivo with an Anger-type camera and in vitro with a sodium iodine crystal well-counter after dissection. The drainage of radioactivity from the anterior chamber had an average half-life of 36 min. The drained activity could be found mainly in blood, liver, kidney, and bone tissue. Moreover, a concentration of radioactivity significantly surpassing the concentration in blood was measured in the right retrobulbar space in 75% of the cases and in the cervical lymph nodes in 50% of the cases. These findings substantiate a communication between the anterior chamber of the eye and the retrobulbar space in the form of a lymphatic or a prelymphatic-lymphatic flow.
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Blood and its main components are commonly used to detect states of selenium deficiency. In order to examine whether human platelets are able to provide better or additional information, improvements of the analytical method resulted in surprisingly narrow normal ranges for selenium and other mineral elements using neutron activation analysis (NAA) and atomic absorption spectrophotometry (AAS), and controlling thermal neutron flux, (n, gamma)-cross sections, mean platelet wet wt, and water fraction of the platelets. Previously reported selenium concentrations in platelets on wet wt basis in the order of 500 ng/g--half of which had been found to derived from early bone marrow precursors using 74Se-selenite--were reproduced by NAA and AAS. However, with the new analytical method the selenium concentrations showed a narrower normal range than that of plasma. Moreover, platelet selenium did not in all cases correlate with plasma selenium. Cellular tissues such as platelets should, therefore, help to detect latent states of selenium deficiency.
The selenium content of platelets is extremely high. About half of this selenium originates from irreversible incorporation by bone marrow precursor cells, which satisfy their need for selenium even under conditions of marked selenium deficiency. In order to study the effect of increased dietary selenium supply on the concentration of selenium, glutathione peroxidase (GSH-Px-) activity, and aggregability of platelets, normal healthy subjects were supplemented with 300 micrograms of selenium as Se-rich yeast/d for 3 mo. No significant effect of Se supplementation on platelet Se and GSH-Px were observed, whereas erythrocytes accumulated Se without reaching saturation. Although platelet aggregability was variable during the period of observation, this was traced back to factors other than selenium, including environmental temperature. This study demonstrates that the selenium concentration of platelets is subject to tight physiological control also at high dietary selenium intakes.