Daniela Patrono

Plasma clearances of branched-chain amino acids in control subjects and in patients with cirrhosis

In an attempt to clarify the pathogenesis of the decreased branched-chain amino acid (BCAA) plasma concentrations in cirrhosis, the plasma clearances were measured in 7 patients with cirrhosis and in 7 age- and sex-matched control subjects. BCAA were given as prime-continuous infusions. The plasma clearances of valine, isoleucine, and leucine, calculated as infusion rate divided by steady state concentration, were low normal in cirrhotics despite hyperinsulinaemia, but different BCAA had different clearances (P less than 0.01). The endogenous basal appearance rates of BCAA, estimated by the basal concentrations multiplied by the plasma clearances, were lower in cirrhotics (P less than 0.025). The apparent theoretical volumes of distribution of BCAA, assessed by the ratio between the clearance and the concentration decay constant after infusion stop, were on average 67% of the total body weight, and were neither different among the three BCAA, nor between the two groups. The urea nitrogen synthesis rate did not increase significantly, suggesting that most of the infused BCAA nitrogen was taken up in peripheral tissues. The decreased concentration of BCAA in cirrhotics (394 +/- 81 mumol/l (mean +/- SD) in the present series vs 510 +/- 68 in controls; P less than 0.025) is not attributable to changes in plasma clearance. The most likely explanation is decreased afflux of BCAA into plasma.

Posttranscriptional changes of serum albumin: Clinical and prognostic significance in hospitalized patients with cirrhosis

Beside the regulation of fluid distribution, human serum albumin (HSA) carries other activities, such as binding, transport, and detoxification of many molecules. In patients with cirrhosis, HSA exhibits posttranscriptional alterations that likely affect its functions. This study aimed at identifying the structural HSA alterations occurring in cirrhosis and determining their relationship with specific clinical complications and patient survival. One hundred sixty‐eight patients with cirrhosis, 35 with stable conditions and 133 hospitalized for acute clinical complications, and 94 healthy controls were enrolled. Posttranscriptional HSA molecular changes were identified and quantified by using a high‐performance liquid chromatography/electrospray ionization mass spectrometry technique. Clinical and biochemical parameters were also recorded and hospitalized patients were followed for up to 1 year. Seven HSA isoforms carrying one or more posttranscriptional changes were identified. Altered HSA isoforms were significantly more represented in patients than in healthy controls. Conversely, the native, unchanged HSA isoform was significantly reduced in cirrhosis. Native HSA and most altered isoforms correlated with both Child‐Pugh and Model for End‐Stage Liver Disease scores. In hospitalized patients, oxidized and N‐terminal truncated isoforms were independently associated with ascites, renal impairment, and bacterial infection. Finally, the native HSA and cysteinylated/N‐terminal truncated isoforms were predictors of 1‐year survival, with greater prognostic accuracy than total serum albumin concentration. Conclusions: Extensive posttranscriptional changes of HSA, involving several molecular sites and increasing in parallel with disease severity, occur in patients with cirrhosis. Altered isoforms are independently associated with specific clinical complications, whereas the residual, native HSA isoform independently predicts patient survival. These findings support the concept of the “effective albumin concentration,” which implies that the global HSA function is related not only to its serum concentration, but also to the preservation of its structural integrity. (Hepatology 2014;60:1850–1859)

Weight loss and sex steroid metabolism in massively obese man

To evaluate the effect of weight loss and diet therapy on plasma sex hormone behavior in male obesity, 9 men with a BMI of 43.4 ± 6.3 participated in an 8-week semistarvation program [whose energy content ranged from 320 to 500 kcalorie/day (proteins 44 to 60 g and carbohydrates 54 to 81 g per day)] followed by a two-week hypocaloric (1000 kcalorie/day) refeeding. In basal conditions, obese patients presented higher estrogen and lower dehydroepiandrosterone sulphate, testosterone (total and free) and sex-hormone binding globulin concentrations with respect to a group of control normal-weight subjects. Cumulative weight loss was 23.9 ± 3.6 kg after semistarvation and 24.4 ± 4.8 kg after refeeding (p = NS). A significant increase in testosterone, free testosterone and dehydroepian-drosterone sulfate was observed throughout the study, irrespective of dietary intake. A transient increase occurred in estrone levels while 17B-estradiol did not change. Gonadotropins and sex-hormone binding globulin values remained unaltered. No relationship was found between sex hormones and dietary energy content or composition. Daily urine free cortisol, which was used as a parameter of adrenal function, fell approximately 50% during semistarvation but returned to baseline values after refeeding. These results show that in massively obese patients weight loss per se may partially reverse sex hormone abnormalities but not sex-hormone binding globulin concentrations. It remains to be determined whether the return to “normal weight” can normalize steroid metabolic derangements in the obese man.

Sex hormones in obese premenopausal women and their relationships to body fat mass and distribution, B cell function and diet composition

We examined sex hormone blood concentrations in a group of 33 obese non-hirsute premenopausal women with normal menses and in 14 age-matched normal-weight controls, and evaluated their relationship with anthropometric parameters, dietary habits and insulin levels. Obese women showed lower than control sex hormone-binding globulin (24.9 ± 14.6 vs 38.6 ± 12.5 nmol/I; p < 0.005) and 5α-dihydrotestosterone (13.7 ± 5.4 vs 18.2 ± 4.8 ng/dl; p < 0.005) values. Despite their consensual behavior, the correlation coefficient between 5α-dihydrotestosterone and sex hormone-binding globulin was not significant in the obese while in controls it was 0.68 (p < 0.01). This suggests that mechanisms operating to lower the plasma levels of these compounds may be regulated differently in obesity. Body Mass Index, per cent body fat and its distribution showed a highly significant negative correlation with sex-hormone binding-globulin and 5α-dihydrotestosterone values. Insulin levels did not appear to be correlated with sex hormone values. On the contrary, in the obese women we found a highly significant correlation between dietary lipids and sex-hormone-binding-globulin levels (r = −0.54; p < 0.005) and between dietary carbohydrates and estrone values (r = 0.47; p < 0.005); all these relationships were independent of body weight. These results confirm that in premenopausal women obesity may be characterized by detectable changes in sex steroid metabolism and suggest a possible causal role not only of the excessive quantity of metabolically active adipose tissue but also of specific dietary factors.

Insulin resistance is the main determinant of impaired glucose tolerance in patients with liver cirrhosis

To clarify the pathogenesis of impaired glucose tolerance in patients with cirrhosis, several factors possibly affecting carbohydrate metabolism were studied in 12 cirrhotic patients with different blood glucose responses to an oral glucose tolerance test. Glucose levels, 120 min after the load, were inversely and significantly related to insulin sensitivity, measured by means of the euglycemic “glucose clamp” technique (r=−0.746). Basal and glucose-induced insulin secretion (insulin and C-peptide levels) only slightly correlated with glucose tolerance, which was not related to functional liver cell mass (galactose elimination), portal-systemic shunting (degree of varices at endoscopy), or maximal glucose-independent insulin secretion (peak C-peptide levels after a glucagon test). Multiple regression analysis identified insulin sensitivity and liver cell mass as the independent variables able to explain most of the variance of 120-min blood glucose (about 84%), and both of them contributed considerably to the regression. While reduced insulin sensitivity is probably the main cause of impaired glucose tolerance, the reduced hepatocellular mass only appears to modulate the degree, and therefore the clinical relevance, of this defect.

A prospective case-control survey of laboratory markers of skeletal muscle damage during HIV disease and antiretroviral therapy.

In a case-control prospective study of approximately 1000 HIV-infected patients, a 15% incidence of muscle laboratory abnormalities was found. No difference emerged between patients with altered creatine phosphokinase levels and controls in the duration of HIV infection, antiretroviral therapy and its duration, selected drug combinations, disease stage, mean CD4 cell count and viraemia, lipodystrophy syndrome, metabolic and bone abnormalities, and eventual myotoxic therapies, except a prevalence of male sex and a longer duration of stavudine administration.

Effect of «Physiological» doses of triiodothyronine replacement on the hormonal and metabolic adaptation to short-term semistarvation and to low-calorie diet in obese patients

In four groups of obese patients matched for Body Mass Index (BMI), we studied the effects of different 3‐week semi‐starvation treatments followed by an 8‐week hypocaloric (1008 kcal, protein 20%, carbohydrate 40%) diet with or without low doses of T3 therapy. Dietary intake (formula diet) in the semi‐starvation period was 480 kcal, with 66 g protein (P) and 51 g carbohydrate (CHO) in groups I and III and with 33 g P and 84 g CHO in groups II and IV. Moreover, groups III and IV were given low doses (20 μg twice a day) of T3 while groups I and II received a placebo. During semi‐starvation periods, a similar fall in BMI values was found in all groups, while during the low‐calorie diet, T3‐treated patients showed the greater BMI reduction. During semi‐starvation, nitrogen balance was significantly more negative in low‐protein than in high‐protein‐treated groups; differences between T3‐treated (III and IV) and control (I and II) groups were not significant over this relatively short treatment period. No differences in 24 h urinary 3‐methylhistidine or alanine excretion were evident between the four groups. During the entire period of study, daily urine creatinine excretion did not change in any group. In conclusion, in our study low‐dose T3 therapy was seen to favour weight loss during low‐calorie diet although negative effects on protein metabolism were not excluded, particularly when relatively small amounts of protein were administered.

Albumin Homodimers in Patients with Cirrhosis: Clinical and Prognostic Relevance of a Novel Identified Structural Alteration of the Molecule

Decompensated cirrhosis is associated to extensive post-transcriptional changes of human albumin (HA). This study aims to characterize the occurrence of HA homodimerization in a large cohort of patients with decompensated cirrhosis and to evaluate its association with clinical features and prognosis. HA monomeric and dimeric isoforms were identified in peripheral blood by using a HPLC-ESI-MS technique in 123 cirrhotic patients hospitalized for acute decompensation and 50 age- and sex-comparable healthy controls. Clinical and biochemical parameters were recorded and patients followed up to one year. Among the monomeric isoforms identified, the N- and C-terminal truncated and the native HA underwent homodimerization. All three homodimers were significantly more abundant in patients with cirrhosis, acute-on-chronic liver failure and correlate with the prognostic scores. The homodimeric N-terminal truncated isoform was independently associated to disease complications and was able to stratify 1-year survival. As a result of all these changes, the monomeric native HA was significantly decreased in patients with cirrhosis, being also associated with a poorer prognosis. In conclusion homodimerization is a novel described structural alteration of the HA molecule in decompensated cirrhosis and contributes to the progressive reduction of the monomeric native HA, the only isoform provided of structural and functional integrity.

Interrelationships between Dietary Carbohydrates, B Cell Function and Rate of Ketogenesis during Underfeeding in Obese Patients

Six matched groups of obese patients underwent 3-week selective hypocaloric regimens which consisted of a 240 or 480 kcal/day liquid formula diets for groups 1-4 and an 800 kcal/day conventional diet for groups 5 and 6. Carbohydrate intake ranged from 19 to 112 g/day so that for each energy level two different amounts of carbohydrates were administered. Body weight loss was similar in groups 1-4 and significantly lower in groups 5 and 6. During treatment fasting serum insulin (but not serum C-peptide) levels and the daily urine excretion rate of C-peptide showed quite a similar fall in all groups. Fasting glucagon levels did not change. The rate of ketogenesis which developed during each nutritional treatment was inversely related to the amount of dietary carbohydrates; moreover, a significant correlation was found between percent variation of ketoacids and those of fasting IRI (r = -0.42; p less than 0.01) and glucose (r = -0.52; p less than 0.01) concentrations, but not with those of fasting C-peptide and its daily urine excretion rate. In conclusion, it seems that during underfeeding (1) low- and high-carbohydrate-containing regimens are substantially equipotent stimuli secretagogues of insulin secretion, and (2) carbohydrate (or glucose) availability affects ketogenesis even through noninsulin-mediated mechanisms.