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Biomedical subjects

S J Piliero

Publications and source records attributed to S J Piliero.

12 recordsLinked to original sources
PubMed1979

The regenerating liver: a site of erythropoiesis in the adult Long-Evans rat.

Erythropoiesis, which is primarily hepatic in the rat during fetal and early neonatal life, shifts almost entirely to the bone marrow in the neonatal-adolescent stage of development. In the adult, extramedullary erythropoiesis has been demonstrated in the liver and spleen under certain pathological conditions when bone marrow red cell production is insufficient. In the present study, erythropoietic foci have been found in young-adult rat liver regenerating 24-72 hr after subtotal hepatectomy. This erythropoiesis is both extravascular and sinusoidal, with some erythroblastic islands noted. The centrolobular hepatic area contains the highest concentration of erythroblasts. Peripheral blood reticulocytosis coincides with the appearance of these cells and this is considered as an indicator of effective erythropoiesis. Liver regenerating after partial hepatectomy produces significant quantities of erythropoietin (Ep) in response to hypoxia. Subtotal hepatectomy may confer upon the adult liver the ability to revert to a fetal-like condition both in its ability to produce Ep and to function as a hematopoietic inductive microenvironment for erythropoiesis.

Age Factors↗
PubMed1979

Reticuloendothelial system (RES) hyperfunction and erythropoietin (Ep) production in the regenerating liver.

Hepatic cells in rats were evaluated after subtotal hepatectomy using scintillation scanning with technetium sulfur colloid (TSC), autoradiography, and microstereology techniques. The ability of the liver to accumulate TSC increased during the course of the regeneration as did the labeling of Kupffer and parenchymal cells with tritiated thymidine (3H-tdR). Kupffer to parenchymal cell number ratios and Kupffer cell relative areas were also elevated, attaining peak values at 72 hours post-hepatectomy. This period corresponds to the time of peak erythropoietin (Ep) production in rats with regenerating livers after nephrectomy and exposure to hypoxia. These findings suggest that the Kupffer cell may function as a cellular site of Ep formation.

Animals↗
PubMed1979

Biocompatibility evaluation of casting alloys in hamsters.

A number of base metal and low gold-content alloys were evaluated in hamster cheek pouches for biocompatibility. No adverse weight changes and no abnormal behavioral patterns were noted in any of the test groups over the 14-day period of the study. Gross examination of the cheek pouches containing the alloys was no different from that of the controls. None of the alloys tested showed significant adverse histopathologic reactions. The recorded changes in incidences and degree of response were essentially no different from those of the negative control material.

Animals↗
PubMed1978

Histologic identification of mast cells in human dental pulp.

Previous investigators who attempted to identify mast cells in the dental pulp have used demineralizing or tooth-splitting procedures to obtain their tissue samples. However, Eda and Langeland15 found that the fluorescence of mast cells is destroyed by acid demineralizing agents. On the other hand, tooth splitting may damage the pulp by crushing it with forceps, or cutting and heating it with burs, stones, or discs. In the present study, we used the extirpated pulps from teeth in which endodontic access openings were made by means of high-speed rotary instruments with water spray. Metachromatic staining methods failed to demonstrate mast cells in any of the non-inflamed pulp specimens. Two of the inflamed pulp specimens revealed numerous mast cells which appeared intact and well preserved with no evidence of degranulation. As to the distribution of the mast cells, there was no correlation with the number and types of other inflammatory cells observed. Although several cells present in the specimens examined were suggestive of mast cells, only those cells that revealed definitive metachromasia were included in this study.

Cytoplasmic Granules↗
PubMed1977

Hepatic regeneration and erythropoietin production in the rat.

The regenerating liver produces erythropoietin in response to hypoxia. The amounts of erythropoietin produced in animals subjected to hepatectomy are significantly higher than those observed in sham-operated animals. Hepatic erythropoietin production appears to be dependent upon the stage of regeneration with the highest levels being produced during the period of greatest proliferation and increase in liver mass.

Animals↗
PubMed1977

Age-related variations in hepatic regeneration and erythropoietin production in the rat.

Erythropoietin (Ep) is produced mainly by the liver and spleen during fetal and neonatal periods and by the kidney during adolescent and adult life. The liver is also an important extrarenal producer of Ep in the hypoxic, anephric adult animal. Subtotal hepatectomy results in a substantial elevation in serum Ep levels at 30-72 hours after hepatectomy in rats subsequently nephrectomized and rendered hypoxic. Ep production is related to the mass of regenerating liver with peak Ep production occurring during times of greatest tissue proliferation. Regenerative and erythropoietic responses to hepatectomy decline with advancing age. Rats undergoing repeated hepatectomies do not recover full liver mass but the initial rate of regeneration increases following each successive hepatectomy. Ep levels decline in anephric hypoxic rats undergoing multiple hepatectomies when compared to sham-operated controls.

Age Factors↗
PubMed1975

Composite materials for dental implants.

The requirements of endosteal dental implants are unique and stringent. The materials currently applied to implantation do not offer convincing evidence of satisfying these needs. This preliminary study reports on attempts at developing materials which would aid in obtaining a mucosal seal to maintain the integrity of the osseous, periosteal, and submucosal compartments from the oral environment and the attachment to bone as related to stress distribution. The materials that were under study were ceramic bonded to base metals and Dacron.

Aluminum↗
PubMedDate not supplied

Mechanisms underlying the suppression of erythropoiesis by hyperoxia.

The 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 less than 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.

Animals↗
PubMedDate not supplied

Isoproterenol-induced changes in cell cycle kinetics of parotid gland acinar cells in 8-day-old rats.

Isoproterenol (IPR) was shown to alter some parameters of the parotid gland acinar cell cycle in 8-year-old rats. Although the deoxyribonucleic acid (DNA) synthetic period (S) was decreased and the pre-DNA synthetic (G1) period was lengthened, there were no differences in the total cycle time. There was an increase in the 3H-thymidine labeling index from 35.7 to 50.8% combined with a decrease in the value of the mitotic index from 2.64 to 2.16% after IPR was administered. The results suggest that noncycling (G0) cells may be involved in the normal differentiation of the parotid gland and that IPR alters the transition of acinar cells between the cycling and noncycling state.

Animals↗