Total and individual free fatty acid concentrations in liver cirrhosis

The finding of high plasma free fatty acid (FFA) levels in cirrhotic patients has been attributed either to decreased hepatic clearance or to enhanced fat mobilization. To better clarify these hypotheses, total and individual FFA and glycerol levels were determined in 21 cirrhotic patients with different degrees of hepatocellular damage (evaluated by liver function tests), portal hypertension (evaluated by endoscopy and clinical signs), and nutritional status (evaluated by anthropometric and biohumoral parameters) and in 10 age- and sex-matched healthy subjects. Glucose tolerance and insulin and glucagon levels were determined in all individuals. Well-nourished and malnourished patients were identified within the cirrhotic group. Plasma FFA and glycerol concentrations were well correlated (r = 0.47, P less than 0.05), levels being significantly higher in cirrhotic individuals than in controls (746.6 +/- 46.29 SE v 359.22 +/- 40.82 mumol/L, P less than 0.001 for plasma FFA; 150.1 +/- 3.12 v 82.5 +/- 9.2 mumol/L, P less than 0.01 for glycerol). Plasma FFA and glycerol showed no correlation with the liver function test results or portal hypertension parameters. Interestingly, plasma levels of FFA and glycerol were influenced by the nutritional status, significantly higher FFA levels being observed in the well-nourished than in the malnourished patients (842.5 +/- 47.5 v 563.4 +/- 78 mumol/L, P less than 0.005). Furthermore, a positive correlation was found between plasma glycerol level and percentage of triceps skinfold (r = 0.45, P less than 0.05). No correlation was found between plasma levels of FFA or glycerol and glucose tolerance, insulin and glucagon.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hyperglucagonemia in liver cirrhosis with portal-systemic venous anastomoses: responses of plasma glucagon and gastric inhibitory polypeptide to oral or intravenous glucose in cirrhotics with normal or elevated fasting plasma glucose levels.

Plasma immunoreactive glucagon (IRG) was examined in volunteers with biopsy-proven cirrhosis of the liver after recovery from surgical portal--caval anastomosis. A wide range of increased total plasma IRG concentrations was found after overnight fast in groups of cirrhotic subjects with and without fasting hyperglycemia. Gel filtration chromatography of plasma showed a major component in the 3500-mol wt fraction in all cases so studied. Administration of glucose i.v. caused rapid suppression of total plasma IRG in normoglycemic and non-insulin-dependent hyperglycemic cirrhotic subjects. After administration of oral glucose, total plasma IRG was suppressed rapidly in normoglycemic cirrhotic subjects, while non-insulin-dependent hyperglycemic cirrhotic subjects exhibited delayed but prolonged suppression. Chromatography of selected plasma with glucose-suppressed total IRG showed a major decrease in the 3500-mol wt component in every case. Exaggerated increments of plasma gastric inhibitory polypeptide were demonstrable in both groups of cirrhotic individuals after administration of oral glucose, and it is speculated that this peptide may contribute to stimulation of glucagon secretion in liver disease associated with insulin deficiency.     

Measurement of reverse triiodothyronine in dried blood spot: Methodology and clinical application as a screening procedure for detection of congenital hypothyroidism

A new sensitive radioimmunoassay method for measuring reverse triiodothyronine (rT₃) concentrations in dried blood samples, designed to screen newborn infants for congenital hypothyroidism, has been developed. Paper strips are impregnated with cord blood and dried. Duplicate 5-mm diameter discs are punched from the paper strips and added directly to the radioimmunoassay reaction mixture. After incubation, bound and free hormone are separated by dextran-coated charcoal. The disc remains in the solution throughout the procedure and the assay can be completed within 24 hr. Recovery of rT₃ is greater than 95% and coefficients of variation are 9.4% (intraassay) and 12.2% (interassay) at an rT₃ concentration of 220 ng/dl. At very low rT₃ concentrations (25 ng/dl), coefficients of variation are 14.2% (intraassay) and 18.7% (interassay). The method readily detects 12.5 ng/dl of rT₃. With this paper disc method, rT₃ was measured in 38 newborns and compared with serum rT₃ measured in the same subjects by a standard radioimmunoassay method. The correlation between rT₃ values measured in dried blood disc and in serum was very high (r = 0.918). The rT₃ in dried blood discs from the cord blood of 745 normal newborns was 228.9 ± 76.0 ng/dl (mean ± SD). In contrast, two infants with proven congenital hypothyroidism had rT₃ values of 35 and 75 ng/dl, respectively. This study indicates that rT₃ can be easily measured in dried blood discs and suggests that the described method may be a useful screening procedure in a program for the detection of neonatal hypothyroidism.     

Glucose modulation of alterations in serum iodothyronine concentrations induced by fasting.

In order to investigate the process by which dietary composition may regulate T4 conversion to T3 and reverse T3, iodothyronine levels were measured in the sera of seven obese subjects during consecutive study periods. These study periods included the ingestion of an approximate weight-maintaining diet (40% carbohydrate, 40% fat, 20% protein) during a control period of 4 days, a fast of 7 days thereafter, and then a 5-day period of glucose ingestion (50 g/day) only. The mean (±SE) serum T3 concentration was 117 ± 8 ng/dl on day 4 of the control period, and gradually decreased to 66 ± 11 ng/dl (p < 0.01) on the last day of fasting. The subsquent administration of glucose was associated with an increase in the mean serum T3 level to 94 ± 10 ng/dl (p < 0.01). Mean (±SE) serum levels of reverse T3 varied reciprocally and were 52 ± 9 ng/dl, 82 ± 12 ng/dl (p < 0.005), and 65 ± 9 ng/dl (compared to fasting, p < 0.05) during the fed and fasting states and during glucose administration, respectively. Furthermore, employing a similar protocol in a different group of subjects, serum sampled during the administration of 100 g of fructose orally during days 8–12 of fasting also was associated with an increase in mean serum T3 and a decrease in mean serum reverse T3, as compared to values obtained on day 6 or day 7 of fasting (T3: 83 ± 6 ng/dl, fasting vs. 111 ± 10, fructose (p < 0.05); rT3: 56 ± 9, fasting vs. 42 ± 6 ng/dl, fructose (p < 0.025)). Serum T4 concentrations were not significantly altered in any study period either during glucose or fructose ingestion. Despite the decrement in serum T3 levels observed during fasting, the mean peak TSH in response to TRH stimulation in a group of 15 obese subjects was decreased during fasting as compared to the fed state (8.1 ± 1.2 μU/ml, fast vs. 12.8 ± 2.0 μU/ml, fed). These observations suggest that both glucose and fructose are capable of modulating serum T3 and reverse T3 levels and that administration of these hexoses in doses of only 100–200 g/day for 5 days may be effective in altering T4 degradative pathways. Furthermore, despite the decreased serum T3 levels, the TSH response to TRH stimulation is decreased, paradoxically, during fasting.     

Studies on the role of the liver and splanchnic tissues in the production of carbohydrate intolerance in uremia

The potential contribution of the splanchnic tissues to the carbohydrate intolerance of uremia was studied in fasted, partially nephrectomized rats. The livers of sham operated (C) and partially nephrectomized (Nx) rats were perfused with physiologic concentrations of potential gluconeogenic substrates using a nonrecirculating perfusion apparatus. Glucose release was slightly greater in the livers of Nx rats as compared to C rats. The portal vein concentrations of the potential gluconeogenic precursors were not different in the two groups. Moreover, there were no differences in the net hepatic extraction of alanine, glutamine or glutamate between the two groups of rats. There was also no difference in the production of glucose from U¹⁴C alanine. The livers of Nx rats, however, demonstrated less net extraction of lactate and released greater concentrations of betahydroxybutyrate. The increased release of glucose by livers of Nx rats may be at least partially due to their greater hepatic glycogen content.     

Glucose tolerance and insulin release in l-asparaginase treated rabbits

Male New Zealand White Rabbits were injected intravenously with either a single dose of 10,000 IU Escherichia colil-asparaginase/kg body weight containing 80 mg of d-mannitol/10,000 IU E. colil-asparaginase or 80 mg d-mannitol kg/body weight alone. Elevated fasting glucose (G) and elevated fasting immunoreactive insulin (IRI) levels were observed in the l-asparaginase treated rabbits at 1 wk. They peaked at 3 wk and declined thereafter. However, fasting G and IRI levels remained significantly elevated at the end of the study (9–15 wk after injection) compared to preinjection levels and levels of the controls. Glucose and IRI levels 0.5 hr post an intravenous glucose load (1 g/kg body weight) also became elevated post l-asparaginase and followed a time course similar to that of the fasting G and IRI levels. These 0.5-hr levels also remained significantly elevated at the end of the study. These data show that a single dose of 10,000 IU/kg body weight produces a hyperinsulinemic diabetes in New Zealand White Rabbits that appears to persist in a mild form for at least 9–15 wk.     

Androgen metabolism in cirrhosis of the liver

Androgen metabolism was studied in male patients with cirrhosis of the liver. The plasma level, metabolic clearance, and production rates of testosterone were decreased while the conversion ratio and rate transport constant of testosterone to androstenedione was increased. Administration of testosterone produced a marked increase in the metabolic clearance rate of testosterone indicating that parenchymal hepatic dysfunction per se was not the cause for the reduced clearance rate. Moreover, the patients were found to have normal testicular reserve for the biosynthesis of testosterone as indicated by an almost fourfold increase in the plasma concentration of testosterone following the administration of human chorionic gonadotropin. These data demonstrate that the reduced production rate of testosterone in male cirrhotics is not due primarily to testicular disease but possibly reflects hypothalamic-pituitary suppression secondary to increased circulating estrogens. The increase in the rate of conversion of testosterone to androstenedione, found in the present study, is consistent with this hypothesis. The present investigation thus provides quantitative data on the hypogonadal state in cirrhosis and suggests possible mechanisms for the alteration in androgen metabolism.     

Effect of dopaminergic blockade on the secretion of growth hormone and prolactin in man

Serum growth hormone (GH) response to insulin and glucagon administration was studied in 12 male and 12 female volunteers under control conditions, and under treatment with pimozide and metoclopramide. In addition, serum prolactin levels were measured during the treatment period. Pimozide and metoclopramide administration had no effect on the GH response to insulin and glucagon. In contrast, serum prolactin levels increased markedly during the treatment period. Dopaminergic blockade is unable to affect GH secretion in response to insulin and glucagon administration in man.     

Formation of β-hydroxyisovalerate by an α-ketoisocaproate oxygenase in human liver

Previously we demonstrated the occurrence of a soluble dioxygenase in rat liver which converts α-ketoisocaproic acid (the keto acid analog of leucine) to β-hydroxyisovaleric acid. Herein we show that human liver contains a similar soluble enzyme which converts α-ketoisocaproate to β-hydroxisovaleric acid. We suggest this enzyme functions as a “safety valve” in liver to help prevent excessive accumulation of α-ketoisocaproate.     

Hypernatremia induces hyperlipemia and a fatty liver

Hypernatremic states, often the result of hypothalamic osmoreceptor dysfunction in humans, are sometimes accompanied by hyperlipemia. To investigate whether hypernatremia could cause hyperlipemia we induced hypernatremia in three groups of rats with their respective controls: Group A rats received hypertonic saline alone intragastrically; group B animals were pair-fed and tap water was substituted for hypertonic saline in the treated group; in group C the rats were again fed intragastrically with a liquid diet mixed with hypertonic saline. Rats receiving excess salt had mean serum Na⁺ concentrations exceeding 159 mmoles/l. While the serum triglyceride values were significantly higher in all hypernatremic rats, hepatic triglyceride content was greater only in group C rats (p < .01). Serum free fatty acids and ketone bodies were also higher in group C rats (p < .01) as compared to controls. These data suggest that hypernatremia by itself leads to hyperlipemia and a fatty liver.     

Evidence for autonomous secretion of prolactin in some alcoholic men with cirrhosis and gynecomastia

Prolactin responses to provocative thyrotropin releasing hormone (TRH) stimulation were evaluated in 20 cirrhotic men with gynecomastia. Fifteen of these cirrhotic men had normal responses with a minimum doubling of the prolactin concentration above basal in response to TRH. Five had abnormal (autonomous) responses in that they failed to double their basal level or had a paradoxical decrease from basal in response to TRH. Moreover, these same five men failed to have a sleep-related increase in plasma prolactin. Three of them also failed to respond to chlorpromazine stimulation. Such abnormal responses are generally associated with the presence of a prolactin secreting pituitary tumor. Basal plasma levels of prolactin were measured in all 20 men studied. The five men who failed to respond to TRH had significantly greater basal prolactin concentrations (80.5 ± 18.7 ng/ml) than did the 15 men who responded normally (33.7 ± 4.3 ng/ml) (p < 0.01), although all 20 had increased prolactin levels relative to that of controls (10.8 ± 0.9 ng/ml) (both p < 0.01).     

Acute myocardial infarction: Sex-related differences in prognosis

In 641 patients (535 men and 106 women) with acute myocardial infarction (AMI), a mortality of 16.63% was recorded among the former and one of 42.45% among the latter. No significant difference was observed in the age groups up to 40 years, in the group from 41 to 55 years, and in those over 71; the difference between percentages (17.09 vs 38.23) was instead statistically significant (p < 0.01) in patients in the age group from 56 to 70 years. This difference was significant (p < 0.01 or 0.001) with regard to mortality in diabetics (21.36% vs 46.34%), nondiabetics (13.09% vs 30.36%), hypertensives (19.72% vs 37.70%) and nonhypertensives (12.86% vs 36.11%), as well as in patients with previous infarction (33.36% vs 81.82%) and in those with first infarction (12.18% vs 31.39%). Since this phenomenon does not seem related to any particular feature of infarction nor to a particular predisposition to specific causes of death, the reasons for such severe prognosis in women require clarification.     

Glucose metabolism in man: Responses to intravenous glucose infusion

We have determined the effect of unlabeled glucose infusions, with and without added insulin, on glucose metabolism in normal male volunteers by means of the simultaneous primed-constant infusion of 6-³H and U-¹³C-glucose. Glucose kinetics were measured after 90 min of infusion. When steady state had been reached, endogenous glucose production (2.53 ± .058 mg/kg·min, $\text{X}$ ± SEM) was suppressed at all rates of exogenous glucose tested (1, 2, and 4 mg/kg·min). The absolute degree of suppression was most marked (75%) at the highest rate of infusion, but the greatest degree of suppression, relative to infusion rate, was at the lowest infusion rate. The control of plasma glucose concentration during the glucose infusion was achieved primarily through regulation of endogenous Ra. The rate of uptake of glucose only increased during the 4 mg/kg·min infusion, even though there were significant elevations in the plasma glucose and insulin concentrations during the 2 mg/kg·min infusion as well. The glucose clearance rate increased only when sufficient insulin was infused with the 4 mg/kg·min glucose infusion to control the hyperglycemia that developed if no insulin was administered. Approximately 43% of the infused glucose was directly oxidized when the infusion rate was 1 or 2 mg/kg·min. That value fell to 32% when the infusion rate was increased to 4 mg/kg·min, regardless of whether insulin was infused or not.     

The glucoregulatory response to intravenous glucose infusion in normal man: Roles of insulin and glucose

In order to differentiate the roles of hyperinsulinemia and hyperglycemia per se in the homeostatic response to i.v. glucose administration, two groups of normal subjects were given either glucose alone (3.5 mg kg^?1 min^?1) or glucose (3 mg kg^?1 min^?1) in conjunction with somatostatin (500 μg hr^?1), insulin (0.15 mU kg^?1 min^?1) and glucagon (1 ng kg^?1 min^?1). Glucose kinetics were measured by the primed-constant infusion of 3-³H-glucose. During the infusion of glucose alone, plasma glucose stabilized at levels 45–50 mg/dl above the fasting values. Endogenous glucose output was markedly suppressed by 85%–90% while glucose uptake rose to values very close to the infusion rate of exogenous glucose. Glucose clearance remained unchanged. Plasma insulin rose three-fourfold while plasma glucagon fell by 25%–30%. When glucose was infused with somatostatin, insulin, and glucagon, plasma insulin was maintained at levels 50% above baseline while glucagon remained at preinfusion levels. Under these conditions, the infusion of exogenous glucose resulted in a progressive increase of plasma glucose which did not stabilize until the end of the study period (190 mg/dl at 120 min). Endogenous glucose production was consistently suppressed (52%) but significantly less than observed with the infusion of glucose alone (p < 0.01). Glucose uptake increased to the same extent as with glucose alone, despite the more pronounced hyperglycemia. Thus, glucose clearance fell significantly below baseline (25%–30%; p < 0.01). These data demonstrate that hyperglycemia per se (fixed, near basal levels of insulin and glucagon) certainly contributes to the glucoregulatory response to i.v. glucose administration by both inhibiting endogenous glucose output and increasing tissue glucose uptake. However, the extra-insulin evoked by hyperglycemia is necessary for the glucoregulatory system to respond to the glucose load with maximal effectiveness.     

Decreased hepatic insulin extraction in subjects with mild glucose intolerance

The fact that hyperinsulinemia occurs in simple obesity and mild glucose intolerance has been well established. Altered hepatic insulin extraction may influence the levels of circulating hormone. The simultaneous measurement of insulin and C-peptide concentrations in peripheral blood enables an in vivo estimation of hepatic insulin removal. To evaluate hepatic insulin extraction, insulin and C-peptide responses to oral glucose were studied in 176 obese and nonobese subjects with normal, impaired, or diabetic glucose tolerance. Insulin levels as well as insulin incremental areas in glucose intolerant subjects were significantly higher than in weight-matched controls. The levels of C-peptide as well as C-peptide incremental areas were only slightly enhanced in subjects with impaired glucose tolerance, whereas they were reduced in subjects with diabetic tolerance. The molar ratios of C-peptide to insulin, both in the fasting state and after ingestion of glucose, as well as the relationship between the incremental areas of the two peptides were used as measures of hepatic insulin extraction. They were significantly reduced in glucose intolerant subjects and, to a lesser extent, in nondiabetic obese subjects. These results indicate that peripheral hyperinsulinemia in subjects with simple obesity or impaired glucose tolerance is a result of both pancreatic hypersecretion and diminished hepatic insulin extraction. In subjects with a more severe degree of glucose intolerance, decreased hepatic insulin removal is the primary cause of hyperinsulinemia.     

Experimental diets affect pancreatic insulin and glucagon differently in male and female mice

The influence of food composition on pancreatic insulin and glucagon content was studied in NMRI-mice of both sexes. The mice were divided into five groups, each given a different diet from the age of 1 mo to 3 mo: (A) laboratory chow as control; (B) high sucrose; (C) high animal fat; (D) high vegetable fat; and (E) a mixed diet with sucrose (40%), fat (40%) and protein (20%). Irrespective of the diet composition, female mice had a higher pancreatic insulin and glucagon content and an overall lower blood-sugar throughout the experimental period. In both sexes, blood sugar was highest in diets with a high fat content. The highest pancreatic insulin content was found in female mice fed the mixed diet (E) and in male mice fed the sucrose diet (B). In male mice, only the vegetable fat diet led to a decreased pancreatic insulin content. Pancreatic glucagon was increased in female mice given vegetable fat (D). In male mice, pancreatic glucagon was depressed with the animal fat diet (C). These results suggest that the composition of food influences the pancreatic content of insulin and glucagon differently in female and male mice.     

Glycerol-induced hypoglycemia: A syndrome associated with multiple liver enzyme deficiencies. Clinical and in vitro studies

A 4 $\text{10}\text{12}$ yr-old white male presented with a history of occasional grand mal seizures and hypoglycemic episodes after overnight fasting. Upon evaluation, he became hypoglycemic after 1 g/kg oral glycerol challenge (plasma glucose: 31 mg/dl in 45 min), but had normal glucose, alanine and fructose tolerance tests. He responded well to a glucagon challenge after 11 hr fast but the became hypoglycemic and could not normalize his blood glucose after a 2nd glucagon stimulation test after 17 hr of fasting. Studies conducted on a percutaneous liver biopsy, and compared with 3 non-hypoglycemic controls, showed reduced activities (20%–30% of normal) of α-glycerophosphate dehydrogenase, α-glycerophosphate oxidase and fructose-1,6-diphosphatase. Alpha glycerophosphate in the patient's liver was elevated. Two types of electrophoresis showed absence of one enzymatically active zone and overall decrease of staining intensity for α-glycerophosphate dehydrogenase. Other liver enzymes tested were normal. The 50% inhibition of the patient's liver fructose-1,6-diphosphatase by α-glycerophosphate occurred, in vitro, at lower concentration than in controls (11 versus 22–40 mM). Electron microscopy revealed hepatocytes with moderately swollen mitochondria that very occassionally contained dense inclusions in the inner mitochondrial matrix. After discharge from the hospital, the patient followed a normal course, with a regimen of multiple snacks and avoidance of high-fat food in the morning.