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J E Hoke

Publications and source records attributed to J E Hoke.

12 recordsLinked to original sources
PubMed1991

Ferric-salicylaldehyde isonicotinoyl hydrazone, a synthetic iron chelate, alleviates defective iron utilization by reticulocytes of the Belgrade rat.

The Belgrade rat has a hypochromic, microcytic anemia inherited as an autosomal recessive mutation. Although transferrin binds normally to reticulocytes and internalizes normally, iron accumulation into cells and heme is much slower than normal. We have investigated the role of the transferrin cycle in this mutant by bypassing transferrin iron delivery with the iron chelate ferric salicylaldehyde isonicotinoyl hydrazone (Fe-SIH). Fe-SIH increases iron uptake into heme by Belgrade reticulocytes, restoring it almost to normal levels. This increase indicates that Fe-SIH delivers iron to a step in iron utilization that is after the Belgrade defect. Depleting reticulocytes of transferrin did not alter these observations. Failure to achieve above normal rates of iron incorporation could indicate damage due to chronic intracellular iron deficiency. Also, iron delivery by Fe-SIH restored globin synthesis to near-normal levels in Belgrade reticulocytes. The rates of glycine incorporation into porphyrin and heme in Belgrade reticulocytes incubated with Fe2-transferrin or Fe-SIH paralleled the rates of iron incorporation into heme. These data are consistent with the concept that iron availability limits protoporphyrin formation in rat reticulocytes. The protoporphyrin used for heme synthesis is provided by de novo synthesis and not by a pool of pre-existing protoporphyrin. The Belgrade defect occurs in the movement of iron from transferrin to a step prior to the ferrous state and insertion into heme. This defect diminishes the synthesis of heme and, consequently, that of protoporphyrin and globin.

Animals↗
PubMed1989

Tissue iron deposition in untransfused beta-thalassemic mice.

Homozygous beta-thalassemic mice show many of the features seen in human beta-thalassemia, such as decreased hemoglobin, hematocrit, and red blood cell count as well as increased reticulocyte count. They also exhibit splenomegaly and a decrease in osmotic fragility of red cells. beta-thalassemic mice were examined for spontaneous iron overload at ages ranging from 20 to 595 days. Accumulation of iron was shown to occur in the spleen, liver, and kidneys but not in the heart. Sections of spleen, liver, kidney, and heart were stained for iron and subjectively scored. Image analysis microscopy was used to examine sections of spleen and liver. Nonheme iron in the four tissues was quantitated using the bathophenanthroline sulfonate colorimetric assay. An increase in tissue iron occurred primarily in the spleen, even before weaning, despite the low iron content of milk. Iron accumulation in the absence of blood transfusion is of interest because iron overload is the major cause of death in human beta-thalassemia.

Aging↗
PubMed1987

Diminished acquisition of iron by reticulocytes from mice with hemoglobin deficit.

Reticulocyte iron and transferrin uptake was studied in hemoglobin deficit (gene symbol, hbd), an autosomal recessive trait in the mouse characterized by hypochromic microcytic anemia, reticulocytosis, hyperferremia, and increased red-cell-free protoporphyrin. Reticulocyte-rich red cells were incubated in vitro in a mixture of 125I-labeled diferric mouse transferrin and 59Fe-labeled iron-saturated mouse plasma. At 37 degrees C, the uptake of transferrin by reticulocytes from affected animals (15 ng/micrograms RNA) was the same as that of reticulocytes from control animals. However, the uptake of iron by affected reticulocytes (0.11 ng/micrograms RNA) was significantly lower than that by control reticulocytes (0.24). At 4 degrees C, transferrin binding by affected and control reticulocytes was again indistinguishable. The deficiency in the uptake of iron by affected reticulocytes was not observed on incubation at 4 degrees C. Scatchard analysis of transferrin receptors on hbd/hbd and control reticulocytes showed no difference in pKD and a slight elevation in number of receptors per reticulocyte for hbd/hbd animals. These findings suggest that hbd/hbd reticulocytes have a defect in iron acquisition that is distal to the binding of transferrin to the cell membrane receptor. This defect is similar to one already described in the anemia of the Belgrade laboratory rat.

Anemia, Hypochromic↗
PubMed1986

Hemoglobin deficit: an inherited hypochromic anemia in the mouse.

The character and pathogenesis of hemoglobin deficit (gene symbol, hbd), an autosomal recessive trait in the mouse, were studied. The main hematological features of hemoglobin deficit are anemia, red cell hypochromia and microcytosis, and reticulocytosis. The absence of raised fecal urobilinogen excretion and frank hyperbilirubinemia and bilirubinuria suggests that excess hemolysis is not the primary cause of the anemia. The raised plasma iron concentration and the failure of the anemia to respond to parenteral iron treatment indicate that the anemia is not due to iron deficiency. The absence of siderocytes and sideroblasts suggests that anemia is probably not due to ferrochelatase deficiency. Thalassemia is excluded by the finding of balanced reticulocyte globin chain synthesis. The markedly elevated levels of free red cell protoporphyrin taken together with the other findings already noted suggest that the anemia of hemoglobin deficit is due to a defect in the erythroid cell iron procurement mechanisms leading in turn to diminished heme and hemoglobin synthesis.

Alleles↗
PubMed1978

Mucosal iron binding proteins in sex-linked anemia and microcytic anemia of the mouse.

The duodenal mucosa of genotypically normal iron replete and iron deficient mice and mice with sex-linked (sla) and microcytic anemias (mk) was examined for the presence of iron-binding proteins. Following continuous, 15 or 120 minute, in vivo intraenteric exposure of a closed duodenal loop to 59Fe, a high speed supernatant of homogenized mucosal tissue was chromatographed on G-200 Sephadex. Two major peaks of 59Fe activity were observed. The molecular weight, and immunological properties of peak I were similar to ferritin whilst those of peak II were similar to transferrin. The distribution of 59Fe between peaks I and II in mk/mk animals was similar to that in genotypically normal iron deficient animals indicating that the intramucosal mechanisms for iron transport were reacting appropriately to the iron deficient state of mice with microcytic anemia. In contrast, the distribution of 59Fe between peaks I and II in sla/Y animals was the reverse of that found in genotypically normal iron deficient animals suggesting the possibility of an intramucosal iron binding protein defect in sex-linked anemia.

Anemia, Hypochromic↗
PubMed1978

Defective iron uptake and globin synthesis by erythroid cells in the anemia of the Belgrade laboratory rat.

Erythroid cell iron uptake and globin synthesis were studied in the anemia of the Belgrade Laboratory rat (gene symbol, b), an autosomal recessive trait characterized by hypochromia and hyperferrinemia. Reticulocyte protein and globin synthesis, as measured in vitro by the incorporation of 3H-L-leucine, were significantly diminished in b/b animals, although no major imbalance between alpha-and beta-chain production was observed in b/b reticulocytes. The incorporation in vitro of 3H-L-methionine into marrow cell globin demonstrated no difference between b/b animals and +/? control animals in the proportion of alpha-to beta-chain production. The transfer of iron from plasma to reticulocytes, as measured in vitro by the uptake of 59Fe, was significantly decreased in b/b animals; Sephadex G 200 chromatography of b/b red cell lysates did not reveal the accumulation of 59Fe in nonhemoglobin fractions found when heme synthesis was inhibited with isoniazid. The magnitude of the reticulocyte iron-uptake defect was greater than the reticulocyte globin-synthesis defect, suggesting that the former is the primary lesion.

Anemia↗
PubMed1977

Ferritin distribution and synthesis in sex-linked anemia.

The ferritin concentration of duodenum, liver, and spleen and the incorporation of L-leucine-3H into immunoprecipitated duodenal and liver ferritin was measured in genotypically normal (+/Y) mice and mice with sex-linked anemia (sla/Y), an X-linked recessive trait determined by a defect in intestinal iron absorption. Liver and splenic ferritin concentration was lower in sla/Y animals than in +/Y animals. Parenteral iron administration produced an increase in the duodenal, liver, and splenic ferritin concentration in both sla/Y and +/Y animals that was most striking in the case of the liver. Duodenal ferritin synthesis, both in vivo and in vitro, was increased in iron-deficient sla/Y animals and decreased in iron-deficient +/Y animals. In contrast, liver ferritin synthesis was decreased in both sla/Y and +/Y iron-deficient animals. In sla/Y animals fed an iron-deficient diet, duodenal ferritin synthesis decreased to near normal levels. These results indicating a high level of duodenal ferritin synthesis in standard-fed mice with sex-linked anemia suggest that the primary genetic defect is more likely a disorder of intramucosal iron transport than a primary disturbance of ferritin metabolism.

Anemia↗
PubMed1975

Red cell iron uptake in hereditary microcytic anemia.

The iron uptake in vitro of red cells from mice with hereditary microcytic anemia (gene symbol mk) was studied to examine the hypothesis of a generalized impairment of cellular iron uptake in this conidition. Reticulocyte-rich red cells from anemic (mk/mk) and acutely bled normal (+/+) mice were incubated in 59Fe-labeled mouse plasma and the radioiron uptake measured. The 59Fe uptake of the mk/mk and +/+ cells was related in the same way to the reticulocyte concentration, the duration of incubation, and the percentage saturation of the plasma iron-binding capacity. However, under the same conditions, the iron uptake of red cells from normal (+/+) mice was greater than that by red cells from anemic (mk/mk) mice. Furthermore, the cellular loss of radioiron on exposure to EDTA was greater for the mk/mk red cells, although the proportion of the radioiron taken up that was incorporated into heme was the same for mk/mk and +/+ red cells. These results support the hypothesis of a generalized impairment of cellular iron uptake in hereditary microcytic anemia and suggest that there might be a defect in red cell receptor sites for transferrin in this condition.

Anemia↗