Albert S. Gordon

Isolation of Mast Cells from Other Cellular Elements of Rat Peritoneal Fluid

Summary A method is described for the rapid separation of mast cells from other cellular components of rat peritoneal fluid. It involves differential centrifugation in a special medium which takes advantage of the greater density of the mast cell.

The Biology of Antithyroid Agents

Publisher Summary This chapter explains that recent work on the antithyroid agents has provided a new approach to the study of thyroid physiology. It has not only made available effective chemical weapons for combating toxic goiter but has also made material contribution to a further understanding of the basic reactions underlying the functioning of the thyroid gland and its relation to the hypophyseal-thyrotrophic mechanism. The marrow-depressing effect of thiouracil has suggested its use in leukemia. Many problems relating to thyroid activity, under normal and abnormal conditions, still remain to be solved. It is most certain that with the interest still mounting in the search for new antithyroid compounds and their mechanism of action, the continued employment of such agents as an experimental tool should prove even more rewarding in the future than it has in the past.

Nucleoside deaminase: an enzymatic marker for stress erythropoiesis in the mouse

The level of nucleoside deaminase was determined in extracts of mouse tissues obtained during a period of accelerated erythropoiesis induced by hypoxia, hemorrhage, or the injection of phenylhydrazine. Under these conditions a striking (10- to 100-fold) elevation of the enzyme activity occurred in the spleen. Similar results were obtained with the injection of purified erythropoietin. In control animals, only a trace of nucleoside deaminase activity was detected in the blood. During the reticulocyte response which followed erythropoietic stimulation, there was a sharp increase in the blood level of nucleoside deaminase, which rose up to 120 times that of control animals. By differential centrifugation, the enzyme was localized to the reticulocyte-rich fraction. Erythrocyte nucleoside deaminase remained elevated even after the reticulocyte count had fallen to normal in the phenylhydrazine-treated mice or to zero after the cessation of hypoxia. There was a very gradual decline in the enzyme activity in the blood which fell to the barely detectable control levels about 45 days after the initial reticulocyte response, a time period which corresponds to the survival of the mouse red blood cell. The persistence of high levels of nucleoside deaminase for the full life span of a generation of erythrocytes formed during stress, viewed in contrast to the virtual absence of the enzyme from normal erythrocytes of all ages, represents an enzymatic difference between the normal red blood cell and the cell produced under conditions of accelerated erythropoiesis.

Effect of Low Pressure on the Blood Picture of Necturus Maculosus

This problem was undertaken for three reasons. (1) There are no well controlled experiments, so far as I know, in which an aquatic form has been subjected to a constant low pressure and examined for changes in its blood picture. Necturus was chosen as the experimental animal because of the readily available source of blood in the afferent branchial arteries of the external gills and because the normal blood picture has been thoroughly worked out by Dawson. 1 (2) Experiments such as those described below supply a method for determining the nature of the red cell ancestors in Necturus by causing them to leave the erythrocytopoietic loci and enter the circulating blood. (3) It is interesting to compare the intensity and duration of the stimulus required to send out erythroid cells into the blood stream of an aquatic form with the intensity and duration necessary to evoke an analogous response in mammals (i. e., increase the reticulocyte and total red cell count). Groups of Necturi were placed in jars of water and subjected to a constant pressure of 330 mm. Hg. in a specially devised low pressure chamber for varying periods up to 9 weeks of continuous exposure. (For the construction of the apparatus, see Dubin. 2 ) The animals were removed once a day for about an hour, and the water in which they were kept was replaced by fresh water. All animals, including the controls, were fed live earthworms twice weekly. In order to minimize the effects of hemorrhage, the small quantity of blood necessary for total counts and 2 smears was drawn on 2 occasions only, once, before the animals were placed in the tank, and later, when they were examined to determine the effects of the reduced pressure.

The effect of prostaglandins A2,E1,E2,15 methyl E2, 16, 16 dimethyl E2 and F2α on erythropoiesis

Abstract Prostaglandins A 2 , E 1 , E 2 , methylated E 2 s and F 2 α affected erythropoiesis and/or erythropoietin (Ep) production. This action is indicated in the exhypoxic, polycythemic mouse where radioiron incorporations into RBC increased after administration of these compounds. The kidney and liver have been indicated through previous studies, to actively participate in Ep production. By the removal of one of these active sites in a murine system treated with prostaglandins it is shown that a response is reflected in Ep levels. Interference of the action of prostaglandins (PG) is altered by the removal of one of these target sites of Ep production. The erythropoietic responses elicited by PGA 2 , E 1 , and perhaps the methylated PGE 2 s act through the liver whereas PGE 2 may operate through a renal pathway for its response. PGF 2α reveals no effect on erythropoietic activity and is no different than that observed for vehicle-treated controls. The prostaglandins tested appear to act primarily through the kidney or liver but the possibility exists that some yet undetermined organ site may also be involved.

Immunological Studies of the Renal Erythropoietic Factor (Erythrogenin)

An immunological study of the renal erythropoietic factor (REF or erythrogenin) has been described. The experiments indicate that the erythropoietic activity of REF, as assayed in the polycythaemic mouse, is neutralized in vitro by addition of serum obtained from a rabbit previously immunized with a REF preparation. These anti‐REF sera had no effect on the biological activity of ESF; however, a depression in erythropoiesis was observed after injection of anti‐REF into normal mice. It is concluded that the injection of an antibody developed against the REF into normal mice interrupts normal erythropoiesis by reducing REF levels; the reduced REF levels lead to decreased amounts of ESF.

Disappearance of exogenous erythropoietin (ESF) from the blood of germfree mice.

Summary A slower rate of disappearance of exogenous ESF from the plasma occurs in germfree mice as compared to normal mice. Higher plasma levels of ESF are maintained in X-irradiated than in non-irradiated mice. Possible mechanisms for these findings include a reduced ability of the liver to destroy ESF in the germfree animal and a decreased capacity of the blood-forming organs in the irradiated mouse to utilize the ESF.

Extrarenal Sites of Erythrogenin Production

Summary Exposure of young nephrectomized male rats to severe hypoxia results in the appearance of highly significant quantities of erythrogenin in the liver and spleen. The amounts evoked in these 2 organs are greater than in the livers and spleens, and approximately equal to those in the kidneys of young male non-nephrectomized rats exposed to a similar degree of hypoxia. This indicates that nephrectomy serves to potentiate extrarenal erythrogenin production in response to hypoxia. The results also suggest that similar biosynthetic pathways operate in renal and extrarenal production of Ep.

Autoradiographic Studies of Human Lymphocytes Cultured in Vivo

Summary Human lymphocytes were cultured in diffusion chambers implanted into the peritoneal cavities of rats. In cultures treated with PHA, the pattern of morphologic transformation and initiation of DNA synthesis paralleled closely similar studies made in vitro. Immunologic stimulation of the human cells by the heterologous host was presumably minimal or absent since control cultures (without PHA) showed no significant degree of blastogenesis when compared with PHA-treated cultures. Minimum DNA synthesis time determined for the PHA-stimulated lymphocytes was 9–10 hr. Values found for the duration of Tc (16–18 hr) and minimum TG2 (2 hr) were shorter than those reported for similar studies in vitro. The in vivo culture method using Millipore chambers appears to offer a more physiologic method for studying lymphocytes.

Mechanisms underlying the suppression of erythropoiesis by hyperoxia.

AbstractThe possible mechanisms underlying the suppression of erythropoiesis in hyperoxic animals were studied. Male Long-Evans rats were injected with cobaltous chloride hexahydrate, a known erythropoietic stimulant. One group was exposed to a hyperoxic environment for ten hours. Both serum levels of erythropoietin (Ep) and renal levels of erythrogenin were significantly lower (p< 0.005) in the hyperoxic animals compared to those left at room air. In addition, inhibitors to Ep or erythrogenin could not be detected in either the serum or renal tissue of the hyperoxic rats. These results indicate that the primary factor responsible for the erythropoietic suppression observed in a hyperoxic environment is a decreased production of erythrogenin which results in turn, in a lowered level of circulating Ep.