The effects of adrenocortical hormones on albumin metabolism studied with albumin-I 131

Is methylprednisolone acetate-related insulin resistance preventable in cats?

Methylprednisolone acetate (MPA) is often prescribed to cats despite being recognized eventually as diabetogenic. To assess MPA-related insulin resistance and evaluate the efficacy of metformin or an obesity and diabetes mellitus (O&D) adjuvant diet as protective factors, a randomized clinical trial was conducted with 28 owned cats undergoing glucocorticoid therapy. A single MPA dose of 20 mg intramuscularly was administered to each cat. Controls (n=10) received only MPA. In the diet group (n=9), replacement of their habitual diet by ad-libitum feeding of a feline commercial O&D diet (Equilíbrio O&D, Total Alimentos ADM) was made. In the metformin group (n=9), metformin chlorhydrate 25mg/cat PO/q24h was administered for 30 days. All patients were clinically evaluated at baseline (T0), day 15 (T15), and day 30 (T30) and blood draw for complete blood count, serum biochemistry, and determination of insulin concentrations. Fasting Insulin Sensitivity Index (SI), Amended Insulin to Glucose Ratio (AIGR), Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), and Homeostatic Model Assessment of beta-cell function (HOMA-B) were calculated based on fasting glycemia and insulinemia. All groups showed significantly higher levels (p < 0.05) of neutrophils, albumin, glucose, cholesterol, triglycerides, and serum insulin at T15. Patients in the metformin group showed also higher SI, AIGR, and HOMA-IR results at T15. Also, at T15, reduced levels (p < 0.05) of eosinophils, lymphocytes, and creatinine were documented in all groups. An MPA single dose induced changes in insulin sensitivity in cats; however, neither metformin nor O&D feeding used in this study was effective as protective factors against MPA-related insulin resistance.

Evaluation of dose-response effects of short-term oral prednisone administration on clinicopathologic and hemodynamic variables in healthy dogs

OBJECTIVE

To determine whether a dose-response relationship exists between short-term oral prednisone administration and common clinicopathologic variables, cardiovascular biomarkers, and systolic arterial blood pressure (SAP) in healthy dogs.

ANIMALS

8 healthy Beagles.

PROCEDURES

Dogs underwent five 5-day experiments (no prednisone treatment [control condition] and prednisone administration at 0.5, 1, 2, and 4 mg/kg, PO, q 24 h), with a 9-day washout period between protocols. Analyses performed before and after treatments included a CBC, serum biochemical analysis, and determination of SAP, fractional excretion of electrolytes, urine protein-to-creatinine ratio, glomerular filtration rate (GFR), serum N-terminal pro B-type natriuretic peptide (NT-proBNP) and plasma cortisol concentrations, and plasma renin activity. Linear mixed-effects modeling was used to compare changes in variables from baseline (day 1 for the same experiment) among treatment conditions.

RESULTS

Changes in serum glucose concentration and GFR were significantly greater after administration of prednisone at 4 mg/kg than for the control condition. Fractional excretion of sodium was decreased from baseline when dogs received 0.5, 1, or 4 mg of prednisone/kg, compared with results for the control condition. Several expected changes in clinicopathologic values were observed after prednisone administration at any dose. Changes in serum NT-proBNP concentration, plasma renin activity, and SAP did not differ from changes for the control condition at any prednisone dose.

CONCLUSIONS AND CLINICAL RELEVANCE

Oral prednisone administration did not affect SAP, NT-proBNP concentration, or measures of renin-angiotensin-aldosterone system activation in healthy laboratory-housed dogs but was associated with relative increases in GFR and serum glucose concentration.

High Dose Prednisolone Lowers Plasma Glycated Albumin Levels Compared to Actual Glycemic Control: A Retrospective Observational Study

INTRODUCTION

Glycated hemoglobin (A1c) and glycated albumin (GA) are often used as indicators of glycemic control. In this study, we determined whether prednisolone (PSL) administration lowers plasma GA.

METHODS

We investigated the factors affecting GA using multivariate analysis in 48 subjects with connective tissue diseases (CTDs).

RESULTS

Multiple regression analysis of GA showed that the dose of PSL [β = - 1.36; 95% confidence interval (CI) - 2.59 to - 0.14; p = 0.03], age (β = 0.06; 95% CI 0.03-0.09; p < 0.001), body mass index (BMI) (β = - 0.14; 95% CI - 0.28 to - 0.01; p = 0.042), and A1c (β = 1.4; 95% CI 0.38-2.42; p = 0.008) significantly correlated with GA (adjusted R² = 0.518). Moreover, GA levels adjusted for age, sex, BMI, plasma albumin (Alb) and creatinine (Cre), and A1c in the subjects taking ≥ 5 mg PSL was significantly lower than those in those taking < 5 mg PSL. Finally, the dose of PSL (as a continuous variable) was negatively correlated with GA adjusted for age, sex, BMI, Alb, Cre, and A1c.

CONCLUSION

High dose (≥ 5 mg) PSL reduces GA concentration more than glycemia.

A discrepancy between plasma glycated albumin and HbA1c levels in a patient with steroid-induced diabetes mellitus

A 57-year-old man was admitted for the treatment of steroid-induced diabetes mellitus (DM). He also had interstitial pneumonia and, to treat it, 20 mg prednisolone had been started in April 2014. Although glycated haemoglobin (HbA1c) level was 7.8% (62 mmol/mol), his glycated albumin (GA) level was normal (13.9%) and the ratio of GA to HbA1c (GA:HbA1c) was lower than that of normal participants and patients with type 2 DM. Plasma GA and GA:HbA1c levels became persistently lower. In September 2015, HbA1c levels measured by HPLC and immunoprecipitation methods were almost the same (6.8% (51 mmol/mol) and 6.7% (50 mmol/mol), respectively), but GA (10.2%) and GA:HbA1c (1.6) were much lower. We report the case of a patient with DM where steroid administration may have caused a decrease in plasma GA and GA:HbA1c levels via increased albumin turnover.

Calcium metabolism in the early posttransplantation period

BACKGROUND AND OBJECTIVES

Information on the time course of serum calcium levels after renal transplantation is scanty, especially in the early posttransplantation period. Both the abrupt cessation of calcium-containing phosphorus binders and vitamin D (analogs) at the time of surgery and the recovery of renal function may be hypothesized to affect serum calcium levels in this period.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

In this prospective observational study, biointact parathyroid hormone, calcidiol, calcitriol, calcium, and phosphorus levels were monitored in 201 renal transplant recipients at the time of transplantation and 3 mo thereafter. In addition, the serum calcium nadir and peak in each individual patient within this time frame were identified and the urinary fractional calcium excretion was determined at month 3.

RESULTS

Serum calcium levels followed a biphasic pattern with a significant decline during the first postoperative week, followed by a significant increase. High pretransplantation parathyroid hormone levels protect against hypocalcemia within the first postoperative week but put patients at risk for hypercalcemia later. These complications, occurring in 41 and 14% of the patients, respectively, most probably reflect inappropriate calcium release from the skeleton, rather than inappropriate renal calcium handling.

CONCLUSIONS

Our data indicate that both hypo- and hypercalcemia are prevalent in the early posttransplantation period. Pretransplantation parathyroid function is an important predictor of posttransplantation calcium levels.

The catabolism of plasma albumin in the rabbit: its rate and regulation

From I¹³¹-albumin studies and previously defined mathematical formulations, rates of breakdown were estimated for native plasma albumin in rabbits. These rates of catabolism per unit weight of animal were remarkably constant and were independent of variations in the steady state values of albumin concentration in the plasma. These results imply that, at least between animals, the breakdown of plasma albumin follows a kinetic process of approximately zero order. It seems plausible that the process operates similarly in individual animals, and hence that albumin is maintained at normal steady state levels in the healthy animal primarily by means of a regulated rate of synthesis.

Review of the toxicology of beclomethasone dipropionate

This paper reviews the published toxicity of beclomethasone dipropionate (BDP). BDP is a synthetic glucocorticosteroid which has a powerful local anti-inflammatory effect but little systemic action. It has been developed for both dermatological and inhaled applications. LD50 values and other acute studies indicated low toxicity. Findings published for repeat dose and reproductive toxicity studies embraced the known range of metabolic and physiological effects of glucocorticoids. For repeat dose studies, these included reduction in body weight gains, cushingoid syndrome in dogs, reductions in the numbers of lymphocytes and the weights of the tissues connected with the immune system, and hepatic glycogen deposition and fatty liver changes. In reproductive studies, there was an increase in the prevalence of cleft palate in mice and rabbits and in the number of dead foetuses, and ossification was retarded. Despite the route of administration, there was a general similarity of effects within and between species. All observations were characteristic of synthetic glucocorticoids and related to the intrinsic effects of these drugs.

Evaluation of nutritional status in patients with endemic pemphigus foliaceus

Sixteen patients with endemic pemphigus foliaceus were submitted to nutritional evaluation. Ten had the localized form of the disease (Group G1) and six the disseminated form (Group G2). The patients were submitted to anthropometric measurements (weight, height, Quetelét index, tricipital skin fold, subscapular skin fold, arm circumference, arm muscle circumference, arm area, arm muscle area, and arm adipose area) and to laboratory evaluation by protein electrophoresis. Arm circumference, arm area and arm muscle area showed lower values in G2 than in G1. Weight and arm muscle circumference tended to the lower in G2 than in G1. Protein electrophoresis showed decreased albumin levels in both groups, with lower values in G2. Overall analysis of the results permits us to conclude that patients with endemic pemphigus foliaceus present signs and symptoms of protein, but not calorie, malnutrition and that this malnutrition is more marked in patients with disseminated pemphigus foliaceus.

Subnormal albumin gene expression is associated with weight loss in immunodeficient/DNA-repair-impaired wasted mice

OBJECTIVE

Mice bearing the autosomal recessive mutation wst express a disease syndrome of immunodeficiency, neurologic dysfunction, increased sensitivity to the killing effects of ionizing radiation, and dramatic weight loss that begins at 21 days of age and progresses until death at 28-32 days of age. Because of the reported association between abnormal liver status and weight loss, we designed experiments to examine expression of a variety of liver-specific genes in wst/wst mice relative to littermates (wst/.) and parental strain (BCF1) controls.

METHOD

Animals were individually weighed from ages 21-28 days to determine relative weight comparisons between wst/wst mice and controls. Dot blot hybridizations were set up to quantitate the accumulation of transcripts specific for alpha-fetoprotein, albumin and other liver-specific gene products.

RESULTS

These results showed a 67% reduction in albumin mRNA expression in livers derived from wst/wst mice relative to both controls. Expression of alpha-fetoprotein, as well as a variety of other liver-specific genes [secretory component (SC), metallothionein (MT-2), cytochrome P1-450 (Cyt P1-450), transferrin receptor (Tf Rec), tumor necrosis factor (TNF), and immune-associated antigen (Ia)], was unaffected.

CONCLUSIONS

These results suggest a relationship between low albumin expression and wasting syndromes in mice. In addition, our data suggest that the wasted mouse may serve as a unique model for subnormal albumin expression.

Meal stimulation of albumin synthesis: a significant contributor to whole body protein synthesis in humans

The present studies were performed to test the hypothesis that the liver, by increasing the synthesis of specific plasma proteins during the absorption of an amino acid meal, may play an important role in the temporary "storage" of ingested essential amino acids and to explore the effects of glucocorticosteroids and recombinant human growth hormone (rhGH) on these processes. The fractional synthetic rates of albumin and fibrinogen were determined using simultaneous infusions of intravenous [1-14C]leucine and intraduodenal [4,5-3H]leucine after 22 h fasting and during absorption of glucose and amino acids in four groups of normal subjects treated for 1 wk with placebo, prednisone (0.8 mg.kg-1.day-1), rhGH (0.1 mg.kg-1.day-1), or combined treatment. When compared with the fasted state and independent of the route of tracer delivery and hormonal treatment, albumin, but not fibrinogen, synthesis increased (P < 0.0001) during absorption of a mixed glucose amino acid meal in all groups. This increase in albumin synthesis accounted for 28% of the increase in whole body protein synthesis associated with feeding and for 24, 22, and 14% in the prednisone, rhGH, and combined treatment groups, respectively. These data suggest that the stimulation of albumin synthesis observed during feeding prevents irreversible oxidative losses of a significant fraction of ingested essential amino acids and may serve as a vehicle to capture excess dietary amino acids and transport them to peripheral tissues to sustain local protein synthesis.

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. Albumin is important as a transport protein, as a measure of evolution and as a model to study secretion following synthesis without the intervening steps of glycosylation. Investigations as to how this protein enters the endoplasmic membrane may well answer some of the questions concerning signal peptide insertion (288). The role of the urea cycle intermediate ornithine and its participation in polyamine synthesis, which has a positive effect on albumin synthesis, is under study. Likewise, the inverse relation between acute-phase protein synthesis and albumin synthesis regulated by interleukin 1 and other cytokines will merit further study. These are a few of the concepts which will be tested in the future.

Antiinflammatory treatment and intestinal alpha 1-antitrypsin clearance in active Crohn's disease

Intestinal alpha 1-antitrypsin clearance was quantified in 17 patients with clinically active Crohn's disease before and after a six-week period of treatment with sulfasalazine and methylprednisolone. Before the study, alpha 1-antitrypsin clearance and, hence, enteric protein loss was elevated as being above control values in 16 patients. After therapy, clearance values decreased in 11 and were normalized in five patients. Serum albumin level was normalized in 11 of 12 patients who had hypoalbuminemia before the study. Clinical condition was improved in all but 1 patient after treatment. There was no close correlation between alpha 1-antitrypsin clearance and disease activity index. These results indicate that antiinflammatory therapy has a beneficial effect on enteric protein loss in Crohn's disease. The measurement of alpha 1-antitrypsin clearance provides a useful adjunctive technique in evaluating intestinal inflammatory activity, and it seems to be of use in following the efficacy of treatment in the course of illness in Crohn's disease.

Acute effects of ethanol intake on albumin and total protein synthesis in free and membrane-bound polyribosomes of rat liver

Controversial results have been reported in the last few years concerning the effects of ethanol on hepatic protein synthesis. In most of the studies no distinction has been made between the synthetic capabilities of the polyribosomes and the secretory product of labelled protein by the hepatocytes. In order to assess the influence of a single feeding of ethanol on the synthesis of albumin and total protein by the polyribosomes of rat liver, free and membrane-bound polyribosomes were isolated quantitatively from rats given 4--8 g ethanol per kg body weight 3--5 h before killing. The following results were obtained: (1) No difference was found in yield and size of free and membrane-bound polyribosomes isolated from control and ethanol-treated rats. The abilities to synthesize albumin and total protein were also equal for polyribosomes from both groups. (2) Addition of 1% ethanol to the incubation mixture of protein synthesis lowered albumin and total protein synthesis by 20%. No effect was observed with 0.5% ethanol. (3) Cell sap prepared from ethanol-treated rats contains a factor or factors which stimulate protein synthesis (10--15%). (4) The albumin mRNA sequence content was not changed in free and membrane-bound polyribosomal RNA fractions of ethanol-treated rats as compared to the control animals.

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. The effects of ethanol infusions cannot be explained as due to the presence of acetaldehyde; some intermediate metabolic step may be the basis of the inhibition of albumin production and polysome disaggregation in the presence of ethanol.

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. Ethanol was shown to interfere with albumin synthesis and the effect was shown to differ when livers from fed and fasted animals were compared. The ethanol effects were also dependent on the metabolism of ethanol rather than on the simple presence of this drug. Acetaldehyde decreased albumin synthesis but in a manner which was distinct from the ethanol effect. Acute ethanol administration under the conditions used in our studies had little effect on secretion of prelabeled proteins from hepatocytes. The implications of studies of the effects of ethanol on liver protein synthesis and secretion are discussed.

Effect of uremia on nutritionally-induced variations in protein metabolism

The effect of uremia on nutritionally-induced variations in protein metabolism was studied in growing rats with chronic, moderate uremia. Plasma and muscle protein synthetic activities and related values were measured from incorporation rates of 14C-leucine infused over a six-hour period. Synthetic activities were compared in the postabsorptive (2 to 14 hr after feeding) and in the fasting (18 to 24 hr after feeding) states. Differences between uremic and control rats were seen in fasting: plasma and intracellular leucine declined in control rats as fasting developed; they rose in uremic rats. In fasting uremic rats, a smaller percent of leucine efflux from extracellular fluid was used for protein synthesis. In a second study, muscle protein synthesis (Sm) and net urea nitrogen production (UNPr) were compared between control and uremic rats which were a) food-deprived but given carbohydrate for 36 hr, and b) fasted for 36 hr. Fasting, as contrasted with carbohydrate feeding, was associated with depressed muscle protein synthesis and increased UNPr in both control and uremic rats; the changes were greater in uremic rats. We conclude that food deprivation for more than 14 hr incurred greater catabolic responses of body protein in moderately uremic rats. The effect was mediated in part by greater suppression of muscle protein synthesis. In contrast, moderate uremia had little discernible effect upon protein metabolism in the postabsorptive state or food deprived state when gluconeogenesis was suppressed with glucose administration.

Albumin synthesis and effect of betamethasone on albumin synthesis in perfused liver of normal and CCL4-intoxicated rats

Synthesis of plasma albumin was studied in perfused liver of normal and CCl4-intoxicated rats, using 14C-bicarbonate method. 1. In normal liver, albumin synthesis averaged 5.6 mg/hr/100 g body weight. 2. In CCl4-intoxicated liver, albumin synthesis decreased to 4.6 mg at acute stage, but restored to 5.1 mg at non-septal fibrotic stage. At septal fibrotic, cirrhotic and cirrhotic stage with ascites, the synthesis rate averaged 4.5 mg, 4.1 mg and 3.2 mg, respectively. From these results, it is inferred that albumin synthesis rate decreases in accordance with the progress of the liver injury. 3. Effect of betamethasone on plasma albumin synthesis in perfused rat liver was investigated. Albumin synthesis rate in normal liver averaged 5.4 mg, and after addition of betamethasone, the rate averaged 4.3 mg, 3.3 mg and 2.8 mg, respectively. The rate after addition of betamethasone increased to 7.3 mg, 5.5 mg and 4.5 mg, respectively. From these results obtained, it is inferred that betamethasone increases plasma albumin synthesis in both normal and CCl4-intoxicated liver. 4. In normal liver, actinomycin-D did not inhibit basal albumin synthesis, but inhibited the increase of albumin synthesis by betamethasone, when actinomycin-D was added together with betamethasone. From these facts, it is concluded that betamethasone is able to induce albumin synthesis.

The influence of drugs and disease activity on biochemical and haematological data in rheumatoid arthritis

Biochemical and haematological data from 218 patients with rheumatoid arthritis were analysed and compared with data from a reference hospital population. The comparison demonstrated significant differences in several biochemical and haematological tests and that the patterns of change are different between males and females. The data were also analysed by conventional statistical methods and discriminant analysis using a computer to establish which tests were most influenced by the activity of the disease and drug therapy. The results obtained demonstrate marked difference between groups of patients with different disease activity or receiving different drugs. The discriminant analysis also identified those tests which differentiate these groups most effectively.

Effects of ethanol on protein synthesis

Cardiac: Cardiac protein synthesis is influenced by the state of nutrition with reduction of cardiac size in starvation. Ethanol per se may not affect this synthesis directly, but the metabolite of ethanol, acetaldehyde, profoundly decreases normal protein synthesis in the heart in vitro. The interference with the synthetic process may play a role in the ultimate cardiomyopathies of malnutrition and alcoholism. Hepatic: In vivo albumin synthesis is sensitive to environment, oncotic pressure, normal balance, nutrition, as well as toxins and state of health. Thus, to study the acute effects of alcohol alone, it was necessary to employ the isolated perfused liver. Fasting reduced albumin synthesis 50%, with loss of RNA and a disaggregation of the endoplasmic membrane bound polysome. Tryptophan, arginine and ornithine added to the perfusate at a final concentration of 10 mM reversed these findings. Alcohol likewise reduced albumin synthesis; disaggregates the bound polysome without a marked loss of RNA. Ornithine, arginine and tryptophan are able to reverse this loss in albumin synthesizing capacity. The combination of fasting and alcohol, while not lowering albumin synthesis below that seen with either stress alone, prevents the recovery from either stress.

Biochemical anomalies of the nephrotic syndrome

The nephrotic syndrome is the only hypoalbuminaemic state frequently associated with hyperlipidaemia. In the presence of a negative nitrogen balance, hyperlipidaemia is metabolically inappropriate and reflects the result of persistent breakaway from free fatty acid control. This lipid abnormality may result in the premature development of ischaemic heart disease in patients in whom it is not possible to control the primary renal abnormality. The authors suggest that future work should be directed towards thyroxine and insulin metabolism in nephrotic states.

A plasma protein fractionation procedure for use in studies of protein metabolism

A two-step method for the separation of five different plasma proteins on a preparative scale, which is capable of being extended to allow the separation of other plasma proteins, is described. The proteins separated were fibrinogen, two alpha(1)-glycoproteins, albumin and transferrin. The alpha(1)-glycoproteins were characterized in terms of electrophoretic mobility, ultracentrifugal and immunological characteristics. By using this method, it was shown that a single sample of plasma could be fractionated to yield purified proteins in sufficient quantity to simultaneously measure the synthesis of the two alpha(1)-glycoproteins, albumin and transferrin in the rat with McFarlane's technique (McFarlane, 1963; Reeve et al., 1963; McFarlane et al., 1965).

The effect of cortisol on the synthesis of rat plasma albumin, fibrinogen and transferrin

A decrease of absolute synthesis of albumin, no change in that of fibrinogen and an increased fractional synthesis of transferrin were observed 3h after intraperitoneal administration of a pharmacological dose of 5 mg of cortisol to 220g rats in the post-absorptive state and previously kept on a diet with 40% protein. The concentration in liver of total free amino acids was practically unchanged at this time. Intraperitoneal administration of a mixture of amino acids with the cortisol raised this concentration and was accompanied by an almost complete de-repression of the synthesis of albumin, with no real effect on that of fibrinogen. In considerable contrast, in rats studied at 24h after intraperitoneal administration of cortisol, and who had been fed once in the interim (but who had received no amino acids intraperitoneally), there was a marked increase in the absolute synthesis of albumin and fibrinogen, with an increase in fractional synthesis that was less proportionately but still very significant and which included transferrin. The amino acid concentrations had risen above the supplemented values at 3h but not as much proportionately as the fractional synthesis rates, and of course not as much as the absolute synthesis rates, of albumin and fibrinogen. These time-dependent effects of cortisol suggest to us that our studies resolve the apparently conflicting results of the effect of cortisol on the synthesis of albumin reported by others.

Effects of carbon tetrachloride on albumin synthesis

The effects of CCl(4) on albumin synthesis were studied employing the isolated perfused liver. Carbonate-(14)C was used to measure newly synthesized albumin. 2.5 ml of CCl(4) was administered by stomach tube 2 hr before perfusion. Albumin synthesis decreased from 36 to 5 mg following the ingestion of CCl(4). Preperfusing the livers for 1 hr before measuring albumin synthesis resulted in an increase to 12 mg, and the addition of tryptophan to a final concentration of 10 mM resulted in a further increase to 19 mg. Cortisone did not protect against the toxic effects of CCl(4) when administered to the donor rabbits. Fasting resulted in an increased sensitivity to CCl(4) and an antioxidant was not effective in protecting against the toxic manifestations of CCl(4).

Alcohol-induced depression of albumin synthesis: reversal by tryptophan

The influence of alcohol on albumin synthesis was studied in the isolated perfused rabbit liver. Carbonate-(14)C was used to label the intracellular arginine pool which serves as the precursor of both the carbon of urea and the guanido carbon of arginine in albumin. The control group synthesized albumin at a rate of 33 mg/100 g of wet liver weight during 2.5 hr of perfusion. When alcohol, 220 mg/100 ml, was added to the perfusate, albumin synthesis decreased to between 7 and 11 mg, less than one-third the control rate. The addition of 10 mM tryptophan to perfusates containing alcohol prevented most of the inhibitory effects and albumin synthesis increased to average 24 mg. Further, the addition of alcohol to the perfusate decreased the hepatic protein/DNA ratio from 70 to 54 and the RNA/DNA ratio from 2.3 to 1.8, changes equivalent to those seen after a 24 hr fast. The addition of tryptophan to the perfusate prevented these findings in both instances. Endoplasmic membrane-bound polysomes were examined for aggregation. Alcohol decreased the quantity of heavier aggregates. Reaggregation occurred when tryptophan was added but quantitative changes in albumin synthesis could not be related to the degree of reaggregation.

Albumin metabolism in rabbits and rats with transplanted tumours

Albumin distributions and turnover rates have been studied using (131)I labelled tracer material in rabbits with Vx2 carcinoma and rats bearing SP7 fibrosarcoma in comparison with control animals. Albumin concentrations were reduced in the tumour bearing animals but plasma volumes increased as the tumours developed. Relative increases were seen in the extravascular distribution of albumin, due partly to albumin pooling in and around the tumours and possibly also to general increases in capillary permeability. In the rats there was a considerable increase in the catabolic rate of albumin which was not related to urinary protein loss. The tumour bearing rabbits showed evidence both of increased catabolism and of decreased synthesis and the combination of the two effects resulted in a greater lowering of albumin concentration than was seen in the rats. Possible mechanisms for these findings and their significance in human malignant disease are discussed.

Augmentation of albumin but not fibrinogen synthesis by corticosteroids in patients with hepatocellular disease

Simultaneous studies of albumin and fibrinogen metabolism have been conducted using the carbonate-(14)C method before and after a 13 day course of prednisolone in eight patients with hepatocellular disease. Initially six patients were hypoalbuminemic. The mean plasma albumin and fibrinogen concentrations and albumin and fibrinogen synthetic rates were all lower than the corresponding values in a group of control subjects. Prednisolone therapy was associated with significant increases in the plasma concentration and synthetic rate of albumin but changes in the intravascular albumin pools were not significant. It is inferred that a low synthetic rate of albumin in a patient with liver disease does not necessarily represent the maximum capacity of the diseased liver to synthesize this protein. Changes in the plasma concentration, intravascular pool, and synthetic rate of fibrinogen were small and inconsistent. The data are compatible with a selective action of corticosteroids on hepatic protein metabolism and with the existence of different mechanisms for the control of albumin and fibrinogen synthesis.

The effect of hydrocortisone on immunoglobulin metabolism

The serum concentration of all subclasses of IgG (gamma(2)A, gamma(2)B, and gamma(1)) as well as IgA and IgM were reduced in normal and low pathogen mice receiving hydrocortisone acetate. Turnover studies using (131)I-labeled gamma(2)A subclass of IgG demonstrated that high dose corticosteroids cause a significantly shortened survival (increased catabolic rate) which contributes to the observed hypogammaglobulinemia. This increase in fractional catabolism is not due to excess loss in the urine or stool but reflects an increase in endogenous catabolism.

Albumin to ascites: demonstration of a direct pathway bypassing the systemic circulation

The transport of plasma albumin and newly made albumin into ascitic fluid was studied in eight patients with cirrhosis and ascites. The thoracic duct was cannulated in two patients and lymph collected over a period of 2 hr. Simultaneously albumin-(131)I and carbonate-(14)C were injected intravenously. The albumin-(131)I measured the transfer of plasma albumin into ascites and into thoracic duct lymph. The carbonate-(14)C, by labeling newly formed albumin, permitted the estimation of the transfer of newly formed albumin into plasma, ascites, and lymph. If the newly synthesized albumin entering ascites and thoracic duct lymph is delivered initially into the plasma, then the ratios of the albumin-(14)C and -(131)I in ascites and lymph compared with the content of albumin-(14)C and -(131)I in plasma would be identical. However, if some newly formed albumin is delivered directly into ascites or lymph, the ratio for albumin-(14)C would be higher than that for albumin-(131)I in lymph or ascites. The ratios of both labeled albumins found in ascites or lymph are expressed as per cent of the total plasma pool. In the eight patients studied 4.2-11.7% of the albumin-(14)C in plasma was found in ascites in 2 hr whereas only 0.4-2.2% of plasma albumin-(131)I entered in this same period. In the two patients studied during thoracic duct lymph drainage 6.1 and 13.5% of newly made albumin-(14)C appeared in lymph in 2 hr whereas only 2.8 and 3.8% of plasma albumin-(131)I was found in the lymph. In cirrhosis with ascites some newly formed albumin entered ascites and thoracic duct lymph by a direct pathway from the liver bypassing the systemic circulation.

Albumin synthesis in cirrhotic subjects with ascites studied with carbonate-14C

The synthesis of serum albumin was measured in 19 patients with cirrhosis of the liver and ascites. Carbonate-(14)C was used to label the guanido carbon of arginine in albumin.18 of the patients had the diagnosis of cirrhosis confirmed by biopsy and/or by the presence of esophageal varices. Seven patients with albumin synthesis rates of 42-105 mg/kg per day demonstrated the lowest serum cholesterol esters and highest serum glutamic oxalacetic transaminase (SGOT) levels, while the seven patients whose albumin synthesis rates ranged from 203-378 mg/kg per day, had significantly higher cholesterol ester levels and significantly lower values for SGOT. The serum albumin levels were equally depressed in all patients. In patients with cirrhosis and ascites albumin production was found to be normal or elevated in seven of the 19 subjects, and only markedly depressed in seven patients, in spite of the fact that the serum albumin level was depressed in all patients.