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Biomedical subjects

L T Chen

Publications and source records attributed to L T Chen.

At least 91 records · Page 5Linked to original sources
PubMed1986

Effects of endotoxin on the splenic microcirculation and its cellularity.

This report describes the effects of endotoxin treatment on the intrasplenic microcirculation and cellularity in rats. Four and 16 h after a single intravenous injection of endotoxin (2 mg/100g body weight), altered intrasplenic microcirculation was observed. The open circulation was reduced from 97% in the control rats to 79% in the endotoxin treated rats, while the closed circulation increased from 3% in the controls to 21% in the endotoxin treated rats. Such changes in the splenic microcirculation may be partly due to the presence of fibrin and the pooling of polymorphonuclear leukocytes and red blood cells in the red pulp. The most apparent cellular changes seen in the white pulp of endotoxin treated rats 16 h after endotoxin injection are the disappearance of lymphocytes from the periarterial lymphatic sheath and the appearance of many giant macrophages within the white pulp. The giant macrophages contain lymphocytes undergoing various stages of degradation. This suggests that the lymphocytes may be injured by endotoxin treatment and are subsequently phagocytosed by macrophages.

Animals↗
PubMed1984

Increased glycogen particles in neutrophils in endotoxin-treated rats.

Leukocyte glycogen in rats was investigated by electron microscopy during the development of endotoxin shock. Although all white blood cells were examined, only mature neutrophils exhibited an increase in cytoplasmic glycogen. Such neutrophils were observed in the vascular spaces of liver, spleen, lung, and bone marrow including the hematopoietic compartment. The increase in glycogen occurred as early as 30 minutes after endotoxin treatment and continued steadily for 16 hours. The increased glycogen content in neutrophils may be due to increased glycogen synthesis. The increase in glucose uptake by neutrophils may contribute to the causes of hypoglycemia in the late phase of endotoxic shock.

Animals↗
PubMed1983

Teratogenic effects of endotoxin on the golden hamster.

Gram-negative urinary tract infections in pregnant women have been implicated as causes of maternal endotoxemia and a subsequent higher incidence of malformations in their offspring. A study was performed to evaluate the effects of endotoxin on the development of the golden hamster. Endotoxin was shown to be extremely embryolethal at higher doses and to produce several malformations at lower doses. The pregnant hamster and its developing embryos were observed to be far more sensitive to endotoxin than species examined by other investigators.

Animals↗
PubMed1983

Effect of splenic congestion associated with hemolytic anemia on mortality of rats challenged with Haemophilus influenzae b.

The effect of splenic congestion associated with acute hemolytic anemia on susceptibility to bacterial infection was investigated in rats inoculated with Haemophilus influenzae b by intranasal (in) or intravenous (iv) challenge. The rats were made anemic by phenylhydrazine treatment and were challenged with 10(6) (in) or 5 X 10(7) (iv) H influenzae b. Forty-eight hours after in inoculation of bacteria, the number of bacteria in the blood was 10 times greater in the anemic rats with extensive splenic congestion than in controls. After iv inoculation of bacteria, a significantly (P less than 0.001) higher mortality rate was found in the anemic rats with extensive splenic congestion and fewer bacteria were present in the spleens but not the livers, as compared to normal rats. Since phenylhydrazine-induced hemolytic anemia exhibited an extensive congestion in the spleen, higher mortality rate observed in the anemic rats challenged with H influenzae b may result, in part, from decreased intravascular clearance of bacteria by the spleen.

Anemia, Hemolytic↗
PubMed1982

Development of mouse embryos in vitro: preimplantation to the limb bud stage.

Mouse embryos were grown successfully in vitro from the blastocyst stage to the limb bud stage. Mouse blastocysts grown in vitro for 10 days showed blood circulation in the yilk sac, forelimb buds, and the primordia of liver, pancreas, and lungs. These characteristics are indicative of a developmental stage equivalent to one-half of the total gestation period in utero. Improvements in culture conditions from days 7 to 9 have made it feasible to culture mouse blastocysts beyond the early somite stage.

Animals↗
PubMed1982

Pregnancy and fetal development in hamsters treated with prostaglandin F2 alpha.

The influence of PGF2 alpha on pregnancy and fetal outcome was investigated in the hamster. Following subcutaneous treatment with 50, 100, 200, 400, and 800 micrograms PGF2 alpha prenatal loss was significantly increased only at the highest dose level. The offspring of the treated animals were all alive and normal. Fetal weight was not affected. However, following intravenous injection of 100 and 200 micrograms PGF2 alpha there was a significant reduction in fetal weight, and at the 400 micrograms dose level an increase in fetal indicate that PGF2 alpha is not teratogenic in hamsters despite the apparent greater sensitivity of the hamster embryo to prostaglandin.

Animals↗
PubMed1981

Intrasplenic pH in normal and phenylhydrazine-induced anemic rats.

Direct measurement of te intrasplenic pH with a microcombination glass pH probe was performed in rats. The pH probe was inserted into the splenic pulp during measurements. In the normal rats, the pH was 7.21. However, in rats with hemolytic anemia induced by phenylhydrazine treatment, the pH decreased to 7.01. The level of lactic acid in the spleen was also determined. The lactic acid content in the spleen of anemic rats was found to be higher (1.20-1.44 micrometeroles/gm spleen) than that of normal rats (0.70-0.74 micrometeroles/gm spleen). The results that the lower pH in the spleens of anemic rats may result from an increase in the lactic acid level in the spleen.

Anemia, Hemolytic↗
PubMed1981

Relationship of alterations in splenic clearance function and microcirculation to host defense in acute rodent malaria.

During the course of Plasmodium berghei malaria in the rat, splenic clearance of damaged uninfected erythrocytes (heated or Heinz body-containing) underwent changes strikingly similar to those of infected erythrocytes. Splenic trapping of abnormal erythrocytes was impaired during the period of rising parasitemia but became supernormal just before the onset of resolution of the acute infection. These changes could be related to the development of splenomegaly and alterations in splenic cordal microcirculation during infection. The relative distribution of flow through the cords was decreased during rising parasitemia and was restored before the onset of resolution. Together, our observations support the hypothesis that altered rheologic properties of infected erythrocytes are a major determinant of their removal by the spleen. These data suggest that the alterations in splenic microcirculation that occur during malaria may have important implications for host defense.

Animals↗
PubMed1980

Megakaryocytes in steel mutant mice.

The megakaryocytes in the bone marrow of steel mutant mice (S1/S1d) and their normal littermates (+/+) were studied by light and electron microscopy with special emphasis on their maturity and distribution in the hematopoietic cords. A higher percentage of megakaryocytes lying against the sinus wall, a higher percentage of the sinus perimeter covered by megakaryocytes and a higher percentage of large megakaryocytes were found in S1/S1d mice than in +/+ mice. In addition, more large megakaryocytes as well as senile megakaryocytes were observed in the spleen of S1/S1d mice than in that of +/+ mice. These observations suggest that more platelets are produced in S1/S1d mice than in +/+ mice on the basis of per unit area of the marrow tissue. Heretofore, the fate of the senile megakaryocytes in the marrow was not known. However, in S1/S1d mice senile megakaryocytes were often found entering the marrow sinuses from the hematopoietic cords. They were also seen in the lung and the spleen where degradation of senile megakaryocytes was observed. These observations suggest that senile megakaryocytes in S1/S1d mice leave the marrow and are removed by the reticuloendothelial system outside the marrow.

Anemia↗
PubMed1980

Intrasplenic microcirculation in rats with acute hemolytic anemia.

Intrasplenic microcirculation in rats with acute hemolytic anemia has been studied by means of the microsphere method. Alteration in the intrasplenic microcirculation was observed in the anemic rats. The open circulation was reduced from 98% in the normal rats to 67% in the anemic rats, while the closed circulation was increased from 2% in the normal rats to 33% in the anemic ones. The reduction in the open circulation in the anemic rats appears to be attributed to the congestion in the splenic cords as a result of the retardation of the passage of damaged red blood cells. Restoration of the open circulation in rats on the first day of full recovery from anemia seems to be associated with a decrease in the congestion in the splenic cords.

Anemia, Hemolytic↗
PubMed1979

Hemopoiesis of the cultured whole mouse embryo.

In vitro cultured murine embryos provide a valuable methodology for studying the ontogeny of hemopoiesis in mammalian embryos. Under improved conditions, 49% of mouse embryos cultured from the blastocyst stage reached the early somite stage. The development of the embryo was arrested at different stages by omitting human cord serum from the culture medium at specific times. These observations suggest the appearance and differentiation of the first hemopoietic cells in the mouse yolk sac to be independent of a normal embryo. In the yolk sac of all cultured mouse embryos, hemopoietic cell differentiated into a major cell type, erythroblasts, and minor cell types such as monocytes, macrophages, and granulocytic cells. A small number of hemopoietic cells remained undifferentiated.

Animals↗
PubMed1978

Microcirculation of the spleen: and open or closed circulation?

By injecting plastic microspheres of a specific size (3 to 4 micrometers) into the circulation and following their movement and distribution in the spleen, it was revealed how blood travels from the arterial capillaries to the venous sinuses. This method demonstrated that both open and closed circulation exist in the spleen and that about 90 percent of the blood takes the open route of circulation in the normal unanesthetized rabbit.

Animals↗
PubMed1977

An electron microscopic study of the spleen of the rat in an acute myelogenous leukemia.

The spleens of rats were studied by light and electron microscopy during the course of an acute myelogenous leukemia, with special reference to infiltration of leukemic myeloblasts in the spleens and to the correlation of leukemic cell infiltration with splenic hematopoiesis and splenomegaly. Leukemic myeloblasts infiltrated the cordal space of the red pulp. Many of them appeared in groups. Even in spleens which were heavily infiltrated, leukemic myeloblasts did not penetrate the while pulp. Massive infiltration and proliferation of the leukemic myeloblasts in the red pulp resulted in splenomegaly. The spleen increased its hematopoietic activity, while the medullary hematopoiesis diminished due to the invasion of leukemic myeloblasts in the bone marrow. Compensatory splenic hematopoiesis occurred in most of the leukemic spleens, but diminished in spleens which were very heavily infiltrated with leukemic myeloblasts. Thus, the degree of splenomegaly and splenic hematopoiesis did not necessarily correspond to the percentage of leukemic myeloblasts in the bone marrow, but rather related to the number of leukemic myeloblasts present in the spleen. A possible role for the splenic sinus walls in promoting compensatory hematopoiesis in the spleen is discussed. A consistent association of type "C" virus particles with leukemic myeloblasts was observed.

Animals↗
PubMed1975

The development of vertebral bone marrow of human fetuses.

The development of the bone marrow of the thoracic vertebrae in seven human fetuses ranging from 95 to 150 mm in crown-rump length (CRL) was studied using light and electron microscopy. In the 95-mm CRL, hypertrophy of the chondrocytes occurred in the central region of the vertebrae, and blood vessels penetrated there from dorsal and ventral sides of the vertebral body. The primary marrow was represented by liberated cartilage lacunnae, occupied by the thin-walled blood vessels and a few mesenchymal cells and mononuclear cells containing granules or vacuoles (GMC). In the 99-mm CRL, chondroclasts were active in removing the cartilage near the central region of the vertebrae. Consequently, a large cavity was formed and occupied by a dilated sinus. GMC were numerous. Osteoblasts and osteocytes were increased in number. Reticular cells with long processes containing large amounts of glycogen began to appear in the extravascular space and formed the loosely arranged cellular meshwork of the hematopoietic compartment. Bundles of collagen fibrils were scattered in the meshwork. Hematopoietic cells were recognizable only in the 105-mm-CRL fetus and increased in number in the 120-mm-CRL fetus. The sinus endothelium was very thin and continuous without apertures except where blood cells crossed the wall. The developing blood cells lying against the outside of the sinus endothelium indented it. At points, collagen fibrils attached to the outside of endothelial cells and appeared to function as the anchoring filaments of lymphatics. The physiologic implications of the association of stromal cells, vascular sinuses, and hematopoietic cells are discussed in relationship to the microhematopoietic environment of the bone marrow.

Bone Marrow↗