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Biomedical subjects

A E Dumont

Publications and source records attributed to A E Dumont.

15 recordsLinked to original sources
PubMed1978

Filtration of circulating particles by splenic autotransplants.

To determine whether filtration in reconstituted perifollicular marginal zones underlies particle sequestration in regenerating spleen transplants, the distribution of IV injected particles of tantalum was examined in autografts freely transplanted into subcutaneous pouches in rats. In two to six weeks old autografts removed one to three hours after particle injection, the reconstituted marginal zones contained practically all of the sequestered tantalum. At 48 hours to 20 weeks following injection, marginal zones were largely free of particles which were distributed extracellularly throughout the red pulp. This sequential pattern of distribution conformed closely to that observed in the intact spleen. The findings indicate that a reconstituted marginal zone allows splenic autotransplants to function as simple mechanical filters. Increased demand for this activity rather than for phagocytosis may be the predominant factor regulating spleen growth.

Animals↗
PubMed1977

Altered erythrocyte osmotic fragility in mice with Ehrlich ascites tumor.

The osmotic fragility of erythrocytes from mice with Ehrlich ascites tumor was compared with that of erythrocytes from normal control animals. Erythrocytes collected from mice 15 days after the ip injection of tumor cells exhibited a uniform pattern of abnormal resistance to hemolysis in hypotonic saline, with 50% hemolysis occurring at an average saline concentration of 0.44% compared to an average of 0.49% for 11 controls a significant difference (P less than 0.0001). Erythrocytes from mice with this tumor apparently undergo an alteration in some component of the cell membrane that regulates either permeability to cations and water or distensibility of the cell.

Animals↗
PubMed1976

Siderosis of lymph nodes patients with Hodgkin's disease.

Lymph nodes removed from 28 untreated patients with Hodgkin's disease all contained markedly increased amounts of hemosiderine, whether or not they were histologically involved in the disease. This finding was particularly striking in patients with the nodular sclerosis type of disease. Abnormal deposits of iron were also noted frequently in lymph nodes containing metastatic carcinoma, lymphoma of non-Hodgkin's type, and reactive hyperplasia, but in each case, with the exception of metastatic squamous cell carcinoma, the amount was significantly less than seen in Hodgkin's disease. The findings suggest that in patients with Hodgkin's disease and perhaps in those with other disorders in which abnormal tissue retention of iron underlies sideropenic anemia, lymph nodes are an important site of iron retention.

Adenocarcinoma↗
PubMed1976

Pathogenesis of ascites in mice with peritoneal carcinomatosis.

For clarification of the mechanisms underlying formation of malignant ascites, alterations in lymphatic transport from the peritoneal cavity and in peritoneal capillary permeability to protein were studied sequentially in mice inoculated ip with Ehrlich-Lettre ascites tumor cells. All animals developed detectable ascites within 5-7 days of the injection. Diaphragmatic and retrosternal lymph vessels became radiopaque within 30 hours of the ip injection of radiopaque contrast material in control animals without ascites and in 12 experimental mice receiving contrast material 1-3 days after injection of tumor cells. No lymph vessels were opacified in 3 of 4 animals when contrast material was injected on day 5 or in any animal receiving contrast material on or after day 7 following the tumor cell injection. We determined alterations in peritoneal capillary permeability in the second group by measuring the concentration of iv injected Evans blue dye in eluates of sections of peritoneum and contiguous underlying tissue removed 3 hours after injection of dye. Permeability averaged 1.5 times normal (P = 0.02) by day 3 after tumor cell injection, 2 times normal by day 5, and 3 times normal by day 7; it remained at the final level. Although lymph drainage became impaired within 24 hours of the detection of ascites, a progressive increase in capillary permeability began 2 days earlier and was probably the predominant alteration in pathogenesis of the effusion.

Animals↗
PubMed1976

Significance of hyperbilirubinemia in acute cholecystitis.

The incidence and significant of hyperbilirubinemia were examined in 110 consecutive patients who entered the hospital with signs and symptoms of acute cholecystitis and underwent laparotomy. Thirty-two or 29 per cent were found to have abnormally elevated serum bilirubin levels on admission. Surgical or roentgenographic examination of the common duct, or both, in 19 of these patients disclosed stones in 13. Serum levels of bilirubin averaged 6.1 milligrams per cent in those with stones and 2.7 milligrams per cent in the others. In the remaining 13 patients, the common duct was not examined, but elevated bilirubin levels, averaging 2.6 milligrams per cent, quickly returned to normal values, and the subsequent course was uneventful. Hyperbilirubinemia significantly increases the likelihood of finding common duct stones in patients with acute cholecystitis, although it also occurs frequently in patients with acute cholecystitis without common duct stones. The underlying mechanism in the latter situation is still oscure but may depend on an alteration in the normal impermeability of epithelium of the gallbladder to conjugated bilirubin.

Acute Disease↗
PubMed1975

Regulation of spleen growth and portal pressure in hepatic shcistosomiasis.

Growth rate and histology of splenic autotransplants in subcutaneous pockets were compared with those of autotransplants in the extrahepatic portal bed in splenectomized mice infected with cercariae of Schistosoma mansoni and in splenectomized uninfected controls. By the fifteenth week after transplantation (and tenth week after injection of cercariae) subcutaneous transplants gained 6.5 times and omental transplants 8.2 times more weight in infected animals than corresponding transplants in uninfected animals. Portal pressures averaged 11 to 13 cm of water in infected animals with transplants and 17 cm in those with intact spleens (compared to that of 6 to 7 cm in controls). Hyperplasia of white pulp with increase in germinal center activity characterized transplants as well as intact spleens of infected animals. The results suggest that a) During the first 10 weeks of experimentally induced infection, portal congestion is not the predominant mechanism regulating increased spleen growth; and b) An intact enlarged spleen appears to contribute to elevated portal pressure.

Animals↗
PubMed1975

Protein content of liver lymph in patients with portal hypertension secondary to hepatic cirrhosis.

Protein content of liver lymph was measured in 14 patients with portal hypertension secondary to advanced hepatic cirrhosis. An abnormally low concentration was found in each patient, averaging 52% of plasma levels. This finding reflects a decreased sinusoidal permeability to protein, the possible effect of "capillarization of the sinusoid" and may bear on development of portal congestion.

Adult↗
PubMed1975

The course and nature of acinar cell death following pancreatic ligation in the guinea pig.

The course and nature of acinar cell death (ACD) following pancreatic ligation in the guinea pig was studied as a possible model for human disease. Ultrastructural studies after various periods of ligation suggested a biphasic pattern of ACD. Early phase ACD involved only a small portion of acinar cells and occurred within a few hours of ligation. It was preceded by swelling and vesiculation of the rough endoplasmic reticulum. Morphometric measurements disclosed celular swelling at this time, and NaCl equilibration studies demonstrated a change in cellular osmoregulation. Late phase ACD, characterized by cellular wasting and autophagic vacuole formation, became prominent several days after ligation. Marked increases in lysosomal enzyme activities were found in tissue homogenates at this time, and acid phosphatase electron histochemistry localized the majority of this increased activity to lysosomes and autophagic vacuoles within the acinar cells. The etiology and nature of both phases of ACD are discussed.

Acid Phosphatase↗