Plasma erythropoiesis inhibitors in humans during hyperbaric hyperoxia]

Before exposure of man to hyperbaric hyperoxia the blood plasma possessed marked erythropoietic activity. Erythropoietins disappeared completely and erythropoiesis inhibitors appeared in the plasma of persons untrained to hyperbaric hyperoxia after a 24-hour exposure to hyperoxic conditions (25% of oxygen in the inhaled air) in the high pressure chamber corresponding to the depth of 63 metres. A reduction of the peripheral red blood indices was observed by that time.     

Changes in erythropoietic activity of the rat plasma in the course of posttransfusion polycythaemia

The aim of this study was to determine the erythropoietic activity of the plasma of polycythaemic rats and of one of its protein fractions playing a role in erythropoiesis regulation. The erythropoietin activity and that of the erythropoiesis inhibitor varied in the examined plasma samples at definite time periods after induction of polycythaemia. It was demonstrated that the most suitable time of plasma collection for the inhibitor investigation is the period between 115 and 187 h after the first transfusion, and that in some cases separation of this factor from erythropoietin present simultaneously in the plasma is indispensable in order to reveal the inhibitory activity. The erythropoiesis inhibitor administered jointly with erythropoietin was found to exert no influence on erythropoiesis either in normal or in polycythaemic recipients of the tested plasma.     

Effect of hyperoxia on erythropoietin biogenesis in the "endocrine" kidney model

The erythropoietin plasma level and RNA synthesis in both kidneys were studied in rats with the H. Selye "endocrine" kidney under 4-hour hyperoxia. It was shown that a short period of hyperoxia leads to a 2-fold decrease in erythropoietin plasma level and to the fall of RNA synthesis in the "endocrine" and intact kidneys. From the evidence obtained it is concluded that hyperoxia inhibits erythropoietin production in the kidneys. Changes in high-polymeric RNA synthesis suggest that DNA-dependent RNA synthesis is one of the mechanisms of the hormone biogenesis.     

Erythropoietic activity of human blood following exposure to hyperbaric hyperoxygenation]

Before exposure of man to hyperoxia the blood plasma posessed erythropoietic activity, but 18 to 20 hours after exposure to compressed air condition in the high pressure chamber corresponding to the depth of 100 metres there proved to be a marked fall of the erythropoietic activity. No statistically significant shifts were revealed in the peripheral blood indices by that time.     

Effect of clorgyline on the intensity of lipid peroxidation and on erythrocyte membrane stability in hyperoxia

Administration of monoamine oxidase type A inhibitor clorgyline to rats before hyperoxia prevented oxygen-induced increase in diene conjugate and Shiff's base brain and plasma levels in hyperoxia. This was due to antioxidative effect of clorgyline which resulted in stabilization of blood cellular membranes. Clorgyline had a normalizing effect on extraerythrocyte hemoglobin level, total peroxidase activity and glucose-6-phosphate dehydrogenase activity in the serum.     

Renal excretion of sucrose after transfusion of sucrose containing red cell concentrates

The elimination of sucrose from plasma and the urinary excretion after transfusions of 394 units of sucrose containing red cell concentrates (RCC) to 108 patients has been studied. 70 mmol sucrose corresponding 3 units of RCC were eliminated from the blood plasma to 90% within 3 hours and excreted by kidneys to 55-80% within 12 hours. The rate of excretion depended on the kidney function. The transfusion of RCC resuspended with the sucrose-rich CSD-AG preservation solution (80 mmol sucrose/l RCC) raised the hemoglobin concentration in patient's blood by 0.5-0.6 mmol/l related to 1 unit of RCC.     

Pretreating rats with hyperoxia attenuates ischemia-reperfusion injury of the heart

Oxidative stress may precondition the heart. The present study investigated whether hyperoxia elicits a preconditioning-like response. Rats were kept in a hyperoxic (>95% O2) environment for 60 or 180 minutes. Hearts were Langendorff-perfused immediately or 24 hours after hyperoxia, and exposed to 25 minutes of global ischemia and 60 minutes of reperfusion. Whole blood was sampled after 60 and 180 minutes of hyperoxia for oxidative stress markers. Hearts were sampled immediately or 24 hours after hyperoxia for measurement of antioxidants, lipid peroxidation products, heat shock protein 72 and endothelial nitric oxide synthase. At the end of reperfusion after 1 h hyperoxia, infarct size was determined by tetrazolium staining. Hyperoxia increased serum levels of conjugated dienes, reduced serum antioxidative protection, reduced reperfusion arrhythmias in most groups, and improved myocardial function. Infarct size was reduced from 45% of myocardial tissue in controls to 22% in treated animals. The myocardial activity of antioxidant enzymes, content of heat shock protein 72, and endothelial nitric oxide synthase in myocardial tissue were not influenced. In conclusion, hyperoxia induces a low-graded systemic oxidative stress, improves postischemic cardiac function and reduces infarct size. The mediators of protection remain to be determined.     

Liproprotein inhibitor of bone marrow cells in tumor-bearing rats.

The role of a plasma inhibitor of erythropoiesis is evaluated in rats with Walker-256 carcinoma (W-256). Plasma from tumor-bearing rats was treated by gel filtration chromatography (Sephadex G-150) and fractions were combined into four pools on the basis of mol. wt. Inhibitory activity was assayed by adding an aliquot of the plasma fractions to normal rat marrow cells which were cultured for 24 hr with and without erythropoietin. 59Fe-heme synthesis, [3H]thymidine DNA synthesis, and 14C-leucine protein synthesis were studied. The results indicated that cultures containing the high mol. wt. pool (greater than 400,000 daltons) had significantly decreased heme, DNA and protein synthesis. This inhibitor also diminished the response to erythropoietin in polycythemic mice. The lower mol. wt. pool stimulated heme synthesis in vitro. To identify the inhibitor further, plasma lipoprotein classes were isolated by density gradient ultracentrifugation. The very low density lipoprotein (VLDL) and chylomicron fractions markedly inhibited DNA, protein and heme synthesis. Low density and high density lipoprotein fractions were inactive. A lipoprotein inhibitor of erythropoiesis was also identified in cancerous ascitic fluid, and to a lesser degree, in normal rat plasma. We suggest that this VLDL inhibitor of marrow erythropoiesis is a contributing factor in the anaemia of cancer.     

Effect of erythrocytic G2-chalone on the erythrokinetics in mice]

It was shown that erythrocytic inhibitor (G2-cheilon) acted both on the proliferating and on differentiated cells of the erythroid series of the mouse bone marrow. The effect of cheilon was expressbd as soon as 3 hours after its administration and lasted for from 8 to 48 hours, depending on the extent of cell differentiation. In case of a single cheilon administration, despite significant erythropoiesis disturbances, erythrocyte count determined 8 to 12 days later persists within the control level. Repeated administration of cheilon was accompanied by a fall of the erythrocyte count at later periods of the experiment.     

LIPOPROTEIN INHIBITOR OF BQNE MARROW CELLS IN TUMOR-BEARING RATS

The role of a plasma inhibitor of erythropoiesis is evaluated in rats with Walker-256 carcinoma (W-256). Plasma from tumor-bearing rats was treated by gel filtration chromatography (Sephadex G-150) and fractions were combined into four pools on the basis of mol. wt. Inhibitory activity was assayed by adding an aliquot of the plasma fractions to normal rat marrow cells which were cultured for 24 hr with and without erythropoietin. ⁵⁹Fe-heme synthesis, [³H]thymidine DNA synthesis, and ¹⁴C-leucine protein synthesis were studied. The results indicated that cultures containing the high mol. wt. pool (>400,000 daltons) had significantly decreased heme, DNA and protein synthesis. This inhibitor also diminished the response to erythropoietin in polycythemic mice. The lower mol. wt. pool stimulated heme synthesis in vitro. To identify the inhibitor further, plasma lipo-protein classes were isolated by density gradient ultracentrifugation. The very low density lipoprotein (VLDL) and chylomicron fractions markedly inhibited DNA, protein and heme synthesis. Low density and high density lipoprotein fractions were inactive. A lipoprotein inhibitor of erythropoiesis was also identified in cancerous ascitic fluid, and to a lesser degree, in normal rat plasma. We suggest that this VLDL inhibitor of marrow erythropoiesis is a contributing factor in the anaemia of cancer.     

Studies on the erythropoietic effect of plasma from anemic toads both with and without testis.

Injection of plasma from experimentally induced anemic toad with intact testis increases erythropoiesis in starved toads evidenced by the increase of red blood cell, hemoglobin and hematocrit, whereas the plasma of castrated and phenylhydrazine-HCl treated anemic toad failed to do so. It can be suggested that the erythropoiesis stimulating factor (ESF) is produced from the testis of toad and the production of this factor (ESF) was found to increase during anemia in an attempt to correct the anemic condition.     

Distribution of the adrenoblocking drug pyrroxan in the bodies of white rats]

The distribution of adrenoblocking drug pyrroxan in the blood plasma and different organs of albino rats had been studied. A rapid appearance of pyrroxan in the brain liver, kidneys, and other organs was shown; its selective accumulation in the hypothalamus was found. As revealed spectrofluorimetrically unchanged pyrroxan molecules disappeared from the plasma and the organs within 2 hours. When pyrroxan-14C was used the radioactivity in the organs was demonstrated for 24 hours, and in the plasma for several days; this indicated the formation of pyrroxan metabolites or its complexes with the plasma proteins and structural elements of the organs. The selective accumulation of pyrroxan in the hypothalamus can account for the high efficacy of this drug in different hypothalamic disorders coursing with the overexcitation of the sympathetic nervous system.     

Alkaline shift in lumbar and intracranial CSF in man after 5 days at high altitude.

In six healthy male volunteers at sea level (PB 747-759 Torr), we measured pH and PCO2 in cerebrospinal fluid (CSF), and in arterial and jugular bulb blood; from these data we estimated PCO2 (12) and pH for the intracranial portion of CSF. The measurements were repeated after 5 days in a hypobaric chamber (PB 447 Torr). Both lumbar and intracranial CSF were significantly more alkaline at simulated altitude than at sea level. Decrease in [HCO3-] IN lumbar CSF at altitude was similar to that in blood plasma. Both at sea level and at high altitude, PCO2 measured in the lumbar CSF was higher than that estimated for the intracranial CSF. At altitude, hyperoxia, in comparison with breathing room air, resulted in an increase in intracranial PCO2, and a decrease in the estimated pH in intracranial CSF. With hyperoxia at altitude, alveolar ventilation was significantly higher than during sea-level hyperoxia or normoxia, confirming that a degree of acclimatization had occurred. Changes in cerebral arteriovenous differences in CO2, measured in three subjects, suggest that cerebral blood flow may have been elevated after 5 days at altitude.     

Renal uptake and excretion of epidermal growth factor from plasma in the rat

The rat excretes around 2 nmol epidermal growth factor (EGF) in the urine per 24 h. The urinary EGF might be derived from plasma and/or might be synthesized in the kidneys. We have used the rat to study the renal uptake and excretion of homologous EGF from plasma. I.v. injected 125I-EGF was removed from the circulation within a few minutes. 5 min after the injection, the kidneys contained 12% of the 125I-EGF. The kidneys seemed to degrade most of the 125I-EGF which they accumulated from blood, as only 4% of the injected label was excreted as intact 125I-EGF in the urine. The amount of endogenous EGF in plasma was under the detection limit of our enzyme-linked immunosorbent assay (0.03 nmol/l) and it remained so after bilateral nephrectomy. Even if plasma EGF was 0.03 nmol/l excretion of EGF from plasma could account for less than 5% of the urinary EGF. This study shows that the kidneys are able to accumulate EGF from plasma and excrete a part of it as intact EGF in the urine. However, excretion of immunoreactive EGF from plasma can only account for a minor part of the urinary EGF.     

Endotoxin extends survival of adult mice in hyperoxia

Research on endotoxin protection from oxygen toxicity is presently limited to the rat model since only rats have been protected by endotoxin. This study reports that endotoxin also extends survival of adult male mice in hyperoxia (greater than 99% oxygen at 1 ATA). Initially, 4-month-old male mice were treated with Boivin-extracted E. coli endotoxin and placed in hyperoxia. Zymosan-primed mice receiving 2 or 10 micrograms endotoxin, and unprimed mice receiving 10-40 micrograms endotoxin, showed moderate protection against hyperoxia; 11/15 Boivin-treated mice survived 120 hours exposure to hyperoxia with time-of-death in hyperoxia = 126.7 +/- 4.4 hours (mean +/- SEM, n = 15). This contrasts with untreated male mice; 0/4 survived 120 hours exposure to hyperoxia with mean survival = 103.5 +/- 3.5 hours. Mice receiving 20 or 60 micrograms Westphal-extracted endotoxin were not protected nor were older female mice receiving 20 micrograms Boivin-extracted endotoxin. This study suggests that age, sex, the extraction method used to obtain endotoxin, and possibly the time of year when endotoxin is administered, are important variables in allowing endotoxin to extend survival of mice in hyperoxia.     

Erythropoietin and erythropoiesis inhibition factor in the newborn and infants with cyanotic heart abnormalities

In the present study, hematocrit, pO2 in the capillary blood, reticulocyte count, erythropoietin activity in plasma and activity of the erythropoiesis inhibition factor in 24-h collective urine were determined in newborns and infants with cyanotic malformations of the heart (transpositions of the big arteries). The plasma of the healthy newborns shows immediately after birth an erythropoietin activity below 1%, as measured by the 59Fe incorporation. The erythropoietin activity of the plasma of infants with cyanotic malformations of the heart is enhanced up to the 14th day of life. In the period of day 14--30 it corresponds to the values of healthy newborns despite the persistence of hypoxia. After the 30th day of life there is again demonstrable an increased erythropoietin activity in the plasma of infants with cyanotic malformations of the heart. Obviously, the low values of 59Fe incorporation from day 14--30 are due to the occurrence of the erythropoiesis inhibition factor. In the urine of infants with cyanotic malformations of the heart there could be demonstrated distinct inhibitions of the stimulated erythropoiesis of the polycythemic mouse. The present studies suggest that the erythropoiesis inhibition factor occurs in postnatal development irrespectively of the degrees of O2-supply of the tissue, and is possibly dependent on the gestational age.     

Clinical and pathological findings on acute phase in two-kidney Goldblatt hypertensive rats

Clinical and pathological changes were investigated on acute phase in two-kidney Goldblatt hypertensive rats. Systolic blood pressure, plasma renin activity, plasma aldosterone and juxtaglomerular cell count (JGCC) increased slightly as early as 7 days after operation. Systolic blood pressure and plasma renin activity rose in the course of time after operation. Juxtaglomerular index (JGI) and JGCC of the clipped kidneys increased and JGI of the opposite kidneys decreased with the increase in systolic blood pressure. These results suggested that juxtaglomerular cells had an important role on acute phase in two-kidney Goldblatt hypertensive rats.     

Rainbow trout (Oncorhynchus mykiss) exposed to oxygen supersaturation and handling stress: plasma cortisol and hepatic glutathione status

Three groups of one summer old rainbow trout were exposed for 22 days either to normoxia (100%) or moderate oxygen supersaturation; 120% and 140%. After the exposure, all groups were transported for three hours in hyperoxic conditions (123% O2) thus simultaneously experiencing density and handling stress. The recovery of rainbow trout to multiple stressors was measured in normoxic conditions. Moderate oxygen supersaturation did not have any negative effects on growth, feed conversion and blood hematology measured over 22 days. On the other hand, the combined effects of the stressful environment in the fish farm and oxygen supersaturation resulted in a 3-fold increase in plasma cortisol levels in those with 100% and 120% O2 supersaturation and a 2-fold increase in the 140% supersaturation group. Furthermore, the stress response after transportation was lowest in the 140% group 24 hours after recovery but highest after 70 hours. Moderate hyperoxia or transportation stress did not change glutathione concentrations in liver indicating that routine sampling does not affect hepatic glutathione status. Our results indicate that moderate O2 supersaturation (<140%) could be considered as feasible in cultivation of rainbow trout since no harmful effects were found.