Hepatic radionuclide planar imaging.

99mTc colloid scans, hepatobiliary scans with IDA derivatives, 67Ga scans, and labeled red blood cells or indium-labeled white blood cells are the major imaging procedures that are currently widely available to visualize the liver. The use of labeled antibodies to a specific tumor is being explored as an investigative procedure but is complicated by the high circulating background activity. In this overview of planar liver radionuclide imaging, it was emphasized that these procedures are noninvasive, may be performed at the bedside, are inexpensive, and provide important data for formulating the further investigation of intrahepatic masses, gallbladder disease, vascular and inflammatory diseases.

Serum albumin.

The liver manufactures albumin at a massive rate and decreases production in times of environmental, nutritional, toxic and trauma stress. Osmotic pressure is a basic evolutionary regulatory factor, and hormonal control over albumin production has been demonstrated. Where and why new or old albumin is degraded are questions which have not been clarified, although the vascular endothelium may well be the degradative site.

The effects of ethanol and hyperosmotic perfusates on albumin synthesis and release.

Sucrose and ethanol inhibit albumin synthesis; sucrose via an osmotic mechanism and ethanol during its metabolism. The present study was undertaken to compare the effects of both of these agents on albumin synthesis and secretion, and to see if ethanol inhibition could be related to an osmotic effect. Male, fed rabbits served as liver donors in all studies.

Prolonged feeding of ethanol to the young growing guinea pig. III. Effect on the synthesis of the myocardial contractile proteins.

Prolonged ingestion of ethanol may lead to a cardiomyopathy, and studies in the experimental animal have demonstrated alterations in protein metabolism. These changes include depression of protein synthesis with acetaldehyde in the acute experiment, in vitro, and after chronic ethanol ingestion in vivo. The present studies were initiated to see if the inhibition of protein synthesis following prolonged ethanol ingestion involved myocardial contractile proteins.

Ethanol and cardiac protein synthesis.

Acute exposure of the heart to ethanol does not appear to alter the rate of young guinea pig cardiac protein synthesis when assayed in vitro. In contrast, the primary metabolite of ethanol, acetaldehyde, markedly diminishes synthesis despite its chronotropic and inotropic effects. On the other hand, after 11-13 weeks of ethanol-drinking during growth and maturation, the synthetic capacity of the working right ventricle was decreased when measured in vitro with normal perfusate.

Prolonged feeding of ethanol to the young growing guinea pig. II. A model to study the effects of severe ischemia on cardiac protein synthesis.

Although acute perfusion of guinea pig hearts with ethanol does not affect cardiac protein synthesis, the latter is inhibited after prolonged ingestion of ethanol when tested in an in vitro system with the working right ventricle. This study reports on the added stress of ischemia on such hearts. Hearts were removed from maturing guinea pigs after 13-16 weeks of ingesting 10% ethanol and were perfused in vitro under conditions of relative ischemia (one-sixth of normal coronary flow) with maintenance of right ventricular load and outflow resistance identical to normal pre-ischemic levels.

The role of the urea cycle and polyamines in albumin synthesis.

Albumin synthesis is stimulated by those amino acids which increase urea synthesis and membrane bound polysome aggregation. Ornithine, an amino acid not incorporated into protein and produced from arginine in the urea cycle, is an albumin-stimulating amino acid and is the precursor of the polyamines, and we have shown that the polyamine spermine promotes bound polysome aggregation. To test the concept that ureogenesis with its generation of ornithine might play a key role in albumin synthesis regulation via the polyamine pathway, isolated livers from fasted donors were perfused with ornithine, alpha-difluoromethyl ornithine (DFMO), and spermine.

Effects of nutrition and alcohol on albumin synthesis.

Albumin synthesis was studied in the isolated perfused rabbit liver under the influence of the stresses of fasting and acute alcohol and acetaldehyde exposure. Fasting clearly depressed albumin production and disaggregated the endoplasmic membrane-bound polysomes. Acute exposure to alcohol produced the same results.

Prolonged feeding of ethanol to the young growing guinea pig: 1. The effect on protein synthesis in the afterloaded right ventricle measured in vitro.

Newly weaned guinea pigs weighing approximately 300 g were fed normal laboratory diets with drinking water containing 5.5% ethanol as the sole source of liquid for periods of 8-11 weeks. Growth was continuous with this diet.

Acute effects of ethanol on hepatic uptake and distribution of narcotics in the isolated perfused rabbit liver.

This study was performed as an initial step in systematically defining the hepatic interactions between ethanol and opioids using a controlled in vitro system. The acute effects of ethanol on the initial uptake and distribution of long- and short-acting narcotics were studied using isolated rabbit liver perfused with rabbit blood without or with ethanol. A pulse injection of 1.

Relative synthesis of cardiac contractile proteins. Evidence for synthesis from the same precursor pool.

The relative molar synthesis of cardiac contractile proteins has been measured in the perfused heart under control haemodynamic conditions. This synthesis, of myosin heavy chains, individual light chains (1 and 2), actin and tropomyosin, was determined from isolated guinea-pig hearts perfused for 3h simultaneously with constant specific radioactivities and concentrations of [3H]lysine and [3H]phenylalanine. The data strongly suggest that all of the proteins studied were synthesized from the same precursor pools of lysine and phenylalanine, since the ratio of the specific activities of the two labels was the same in all of the proteins.

Protein secretion in suspensions of isolated rat hepatocytes: no influence of acute ethanol administration.

The effect of ethanol on the secretion of proteins was studied in hepatocytes isolated from 24-h fasted rats and from fed rats. Hepatocytes were isolated after collagenase disruption of the liver and incubated in a standard medium containing amino acids, bovine albumin, glucose, penicillin and streptomycin in HEPES buffer. Cell viability was determined by urea production and trypan blue exclusion.

Spermine stimulation of CCl4 depressed protein synthesis in rabbits.

CCl4, 2.5 ml/kg body weight, was administered via a gastric tube to fed rabbits 2 hr before the livers were removed and perfused. Electron microscope studies of the liver showed that CCl4 caused a decrease in the rough endoplasmic reticulum and an increase in the smooth reticulum.

Effects of ethanol on protein synthesis and secretion.

Liver protein synthesis involves a complex series of reactions which is influenced by hormones, nutritional state and general health of an animal. The secretory processes for proteins, such as albumin, also interact with the protein synthetic machinery of the liver. Alcohol may affect synthesis and/or secretion at a number of loci and the mechanism of alcohol's action could depend on the immediate state of the experimental tissue.

Post ischemic reperfusion and anoxic perfusion in the isolated heart: alteration in distribution of radionuclides and in protein synthesis.

1. Reperfusion after ischemia and perfusion with total anoxia were studied in the isolated guinea pig heart model which permits right ventricular loading and constant coronary perfusion. Deprivation of oxygen in both situations resulted in a marked shift of circulation from the left to the right ventricle with markedly increased spaces of distribution of 99mTc radionuclides and albumin in the latter.

The effects of acetaldehyde and disulfiram on albumin synthesis in the isolated perfused rabbit liver.

Acetaldehyde infusions inhibit albumin synthesis in the liver from fed donors but not in the livers from fasted donors. The inhibition of acetaldehyde metabolism with 4-MP and disulfiram reverses this finding, suggesting that acetaldehyde per se is not the toxic agent. Disulfiram stimulates albumin synthesis in livers from fasted donors, and the presence of acetaldehyde does not prevent this process.