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Biomedical subjects

C J Ryan

Publications and source records attributed to C J Ryan.

At least 73 records · Page 4Linked to original sources
PubMed1981

The outcome of patients with pleural effusion of indeterminate cause at thoracotomy.

In 51 patients, the cause for pleural effusion remained indeterminate immediately after thoracotomy. Thirty-one (60.8%) had no recurrence of the effusion, and no cause became apparent during a follow-up period of from 1 1/2 to 15 years. Two patients (3.9%) died relatively soon after thoracotomy, but death was not clearly related to the pleural effusion. In 18 patients (35.3%), the cause of the effusion became apparent from 12 days to 6 years after thoracotomy. In 13 of these 18 patients, malignancy (6 patients with lymphoma, 4 with malignant pleural mesothelioma, and 3 with other malignancy) was ultimately diagnosed. In 3 of the 18 patients, the ultimate diagnosis was a collagen-vascular disease, and 1 patient each had the yellow-nail syndrome and mitral stenosis.

Adult↗
PubMed1979

Rupture strength of skin wounds in jaundiced rats.

The rupture strength of 7-day-old wounds in normal rats, in rats in which there had been a previous skin incision, and in sham bile-duct-ligated and bile-duct-ligated jaundiced groups of rats was studied. It was found that wounds in jaundiced rats were significantly weaker than the wounds in the normal group of rats. Skin wounds in normal animals were significantly stronger than wounds in animals with sham bile-duct ligation. No difference was seen between sham bile-duct-ligated and bile-duct-ligated jaundiced rats.

Animals↗
PubMed1979

Activated charcoal haemoperfusion via an extracorporeal circuit in the unrestrained and unanaesthetized rat.

Repeated haemoperfusion over activated charcoal was performed in unanaesthetized and unrestrained rats, using a specially designed system. This allowed the effects of haemoperfusion on body weight, organ weight and various biochemical and haematological parameters to be studied, without the possible influence of repeated stress and exposure to anaesthetic agents. The procedure was well tolerated, even after 4 consecutive haemoperfusions. Changes in body weight occurred, but no significant difference was noticed between animals subjected to 4 consecutive haemoperfusions and those perfused through empty columns. Organ weight of liver and spleen were comparable to control values, but kidney weight increased after haemoperfusion over activated charcoal, but not in control animals. A progressive rise in leucocyte count was found after successive haemoperfusions, but levels returned to normal 21 days after their initial operative procedure. Platelet counts fell after charcoal haemoperfusion, but returned to within normal levels before the next perfusion.

Animals↗
PubMed1978

Hepatic blood flow studies in the rat before and after portacaval transposition.

Portacaval transposition diverts portal blood from the liver and allows systemic venous blood from the caudal inferior vena cava to perfuse the portal bed. Measurement of hepatic tissue blood flow before and after portacaval transposition and its relationship to the liver atrophy seen after portacaval transposition is important. Sequential measurements of hepatic tissue blood flow carried out before and after portacaval transposition have been made using the clearance of the inert radioactive gas 85Krypton after injection into the portal bed. These measurements reveal that hepatic tissue blood flow is not diminished following the operation. The relative liver atrophy seen after portacaval transposition is therefore consequent on portal venous diversion but not on diminished hepatic perfusion.

Animals↗
PubMed1978

Liver blood flow measurements in the portacavally transposed rat before and after partial hepatectomy.

The haemodynamic changes following partial hepatectomy (PH) in the portacavally transposed rat have been studied using an 85Kr clearance technique. Liver blood flow measurements (LBF) were made before and after portacaval transposition (PCT) and PH was performed either immediately or at 3 weeks after transposition and further blood flow measurements made. No change in LBF was noted after PCT compared with preoperative values. Following PH in the portacavally transposed animals there was no marked increase in LBF. It is suggested that the liver atrophy consequent on portal diversion is due to deviation factors in portal blood and not to a decrease in absolute LBF. Regenerative hyperplasia occurs in the absence of the post-hepatectomy rise in LBF seen in normal animals.

Animals↗
PubMed1978

Changes in the nuclei of astrocytes following portacaval shunting and portacaval transposition in the rat.

Structural abnormalities are found in the astrocytes of the dentate nuclei of animals after portacaval shunting (PCS). These changes are also found in man in association with portal-systemic encephalopathy. To investigate the relationship between portal-systemic shunting and hepatocellular dysfunction in the pathogenesis of these changes, PCS and protacaval transposition (PCT) were performed in rats. PCT diverts portal blood into the systemic circulation, but retains normal total hepatic blood flow by perfusion with systemic venous blood. Liver function and mass are better preserved than after PCS. Abnormal glial cells were found in 4.03% of animals following sham operation, 13.45% following PCT, and 19.09% following PCS. Both experimental groups differed significantly from control animals, and the number of abnormal cells was significantly higher after PCS than after PCT. These findings are in keeping with the hypothesis that hepatocellular dysfunction plays an important role in addition to portal-systemic shunting in the aetiology of the structural changes in the brain associated with hepatic encephalopathy.

Animals↗
PubMed1977

Measurement of liver blood flow in the rat using an 85Krypton clearance technique.

A method for the measurement of liver blood flow (LBF) in rats has been developed by recording the clearance of 85Kr from the liver after injection of a solution of the gas into the portal vein. This technique provides a measure of tissue perfusion at a cellular level. The animal preparation was maintained in a stable haemodynamic and respiratory state for up to 4-3 h by careful fluid and anaesthetic control. Stability of the model was reflected by relative constancy of the LBF measured throughout the experiment in all of the animals studied. The mean LBF determined in six rats was 2-41+/-(s.d.) 0-50 ml/g/min.

Animals↗
PubMed1977

Liver tissue blood flow measured by 85Kr clearance in the anaesthetized rat before and after partial hepatectomy.

The changes in liver haemodynamics following partial hepatectomy (PH) were studied using an 85Kr clearance technique to measure perfusion in the livers of rats before and after both PH and sham operations. Post-operative measurements were made for 8 h following operation and also at 21 and 35 h, when uptake of tritiated thymidine into DNA is maximal in regenerating rat liver. Sham operation did not influence hepatic perfusion, arterial pressure or portal pressure. PH induced an early increase in perfusion of 293% in spite of a decrease in arterial blood pressure during the initial 4 h. The increase in perfusion lasted at least 8 h, had returned to normal values by 35 h, and was not explained solely by an observed elevation of portal pressure of 50% which returned to normal 5 h postoperatively. The total volume flow to the liver remnant after PH, however, was essentially the same as the flow to the liver before operation.

Animals↗
PubMed1977

Portacaval transposition and subsequent partial hepatectomy in the rat: effects on liver atrophy, hypertrophy and regenerative hyperplasia.

Portacaval transposition diverts portal blood from the liver. It allows systemic venous blood to perfuse the portal bed. Body weight and liver weight have been followed before and after portacaval transposition and control procedures in rats, and the DNA activity ratio studied in the liver of rats after partial hepatectomy in protacavally transposed animals. The results suggest that the liver atrophy seen after portal diversion is a result of diversion of trophic substances in the portal blood rather than of a decrease in absolute liver flow. Recovery of liver weight after partial hepatectomy in portacavally transposed animals occurs within the same time as in control animals, and the time course and magnitude of regenerative hyperplasia, as assessed by liver DNA activity ratio, is unimpaired.

Animals↗
PubMed1976

The immune response in cirrhotic rats. The induction of tolerance to orally administered protein antigens.

Hepatic cirrhosis reduced the susceptibility of rats to the induction of tolerance by the oral administration of a protein antigen. Rats with portacaval shunt were rendered tolerant as readily as normal rats. The orally induced state of partial tolerance was shown to be dependent on thymus-dependent lymphocytes: B lymphocytes reacted normally to challenge when injected with T lymphocytes from normal rats. Several factors may contribute to the reduced responsiveness of the cirrhotic rats to the tolerance regime. First, the cirrhotic liver was shown to have a reduced capacity to separate immunogen from tolerogen. Second, because of the reduced phagocytic capacity of the liver, increased quantities of lipopolysaccharide, derived from intestinal microorganisms, enter the blood stream. These substances and products of hepatocyte necrosis have adjuvant activity and may therefore contribute to the changed state of responsiveness of rats with cirrhosis.

Administration, Oral↗
PubMed1976

The effects of portacaval shunting and portacaval transposition on serun IgG levels in the rat.

In rats subjected to end-to-side portacaval shunt and to portacaval transposition, serum IgG levels rose progressively by approximately 100% over a 5-week period. During the same period, sham-operated control animals showed only the increase expected with age. Rats with a portacaval shunt showed a greater fall in body weight and liver weight than did those with a portacaval transposition, and also showed a greater fall in levels of liver-synthesized proteins. Serum enzyme levels were markedly elevated during the first 48 hr after portacaval shunting, whereas after portacaval transposition the elevation was very small. Over the following 5 weeks enzyme elevation continued to be margiallly greater in the portacavallly shunted animals. Because IgG levels rose to a similar degree in both groups of animals, the prsent results support the hypothesis that hypergammaglobulinemia is due to the shunting of antigen-rich portal blood past the reticuloendothelial cells of the liver, and the hepatocellular damage does not play a major role in this process. The etiology of hypergammaglobulinemia in chronic liver disease in man may be similar.

Alanine Transaminase↗
PubMed1971

Portal venous injection in the rat.

A technique for subcutaneous transposition of the spleen in the rat is described. The preparation has been developed as a reliable means of transplenic portal injection. It has been shown that different substances injected into the pulp of the transposed spleen are cleared and not pooled in the organ. The development of porta-systemic venous communications has been demonstrated and their detection radiologically and by isotope techniques is illustrated. It is suggested that the technique outlined in this communication may be of value in the study of the portal circulation, the function of the liver, and in the investigation of drug action.If adequate porta-systemic venous connexions are present the portal vein can be tied above its splenic tributary and the animal will survive. The method offers a simple means of porta-systemic diversion in the rat.

Albumins↗
PubMedDate not supplied

Portacaval transposition in the rat: definition of a valuable model for hepatic research.

Portacaval transposition (PCT) in rats results in a smaller loss of body mass and liver mass than end-to-side portacaval shunt (PCS). Detailed studies of liver function, mass and histology were not previously available and have been undertaken in two different strains of growing rat in order to define the value of this model. PCT rats gained weight normally, while only 50% of PCS rats regained their preoperative weight by the tenth week. Wet and dry weights of liver fell relative to control values after both operations, but the fall was significantly greater after PCS than after PCT: there were parallel changes in hepatocyte size. There was a marked rise in liver-associated enzymes in the first 2 days after PCS only, and minimal enzyme elevations persisted in this group. The extent of cellular damage seen histologically closely parallelled the rise in SGOT in individual rats. At 72 hr, PCS rats showed focal necrotic changes, and by 10 weeks there was marked fatty infiltration: PCT rats had normal histology or showed minimal changes. PCT therefore provides a model in which there is total portal diversion without the more severe effects of the conventional PCS on hepatic structure and function. This has particular value in studies of experimental hepatic encephalopathy, of hormonal and amino acid changes after portal diversion, and of factors initiating or controlling liver regeneration.

Alanine Transaminase↗