Body composition and heart rate variability to achieve dry weight and tolerance.

Autonomic dysfunction in patients with end- stage renal disease is associated with poor prognosis. Heart rate variability (HRV), determined by the standard deviation of the normal R- R interval, has been reported to be a useful evaluation of cardiac autonomic modulation. The relationship between HRV and hydration status (HS) can be analyzed by whole body bioimpedance spectroscopy. This allows a classification of patients according the combination of HS with predialysis systolic blood pressure. Differences in HRV can be studied in patients with high over hydration, but normal or low blood pressure, with respect to fluid-overloaded/hypertensive patients and normohydrated/normotensive patients. In conclusion, the assessment of the autonomic nervous system response to the hemodialysis treatment in end- stage renal disease patients, classified according to a reliable and quantitative measurement of their fluid overload, could permit better management of both arterial blood pressure and HS.

Carotid intima-media thickness and liver histology in hemodialysis patients with nonalcoholic Fatty liver disease.

The prevalence of atherosclerotic cardiovascular disease in chronic hemodialysis (HD) patients has been demonstrated to be higher than in healthy people. Severe liver fibrosis is strongly associated with early carotid atherosclerosis and it might reduce the survival of patients who undergo both renal replacement therapy and transplantation. We wanted to assess whether nonalcoholic fatty liver disease (NAFLD) was associated with altered intima-media thickness (IMT) in HD patients as an independent marker of subclinical atherosclerosis. We enrolled 42 patients undergoing HD and 48 patients with normal renal function, all of them with high levels of aminotransferases and an ultrasonographic diagnosis of liver steatosis. The control group consisted of 60 healthy subjects. Laboratory tests for inflammatory and oxidative markers, ultrasonographic liver evaluation, carotid IMT measurement, and liver biopsy were performed. Different degrees of fibrosis were detected in our study cohort. Worse liver histopathological scores and higher plasmatic levels of C-reactive protein, reactive oxygen species, and vascular cell adhesion molecule-1 were found in HD patients. Carotid IMT was significantly higher (p < 0.005) in patients with histological steatosis. HD patients may develop active and progressive chronic hepatitis faster than patients with normal renal function and the thickness of their carotid intima-media might be markedly increased. These two conditions seem to be independent on classical risk factors and on metabolic syndrome. They might be related to the high levels of oxidants and to the inflammatory state, which are typical of patients undergoing HD. Independently related with the traditional risk factors for cardiovascular disease, nonspecific inflammation and oxide-reductive imbalance may play an important role in the progression of NAFLD and atherosclerotic disease in HD patients.

Luminance and chromatic visual evoked potentials in type I and type II diabetes: relationships with peripheral neuropathy.

The objective of the study was to investigate the subclinical visual deficit in type I and II diabetes, and its relationship with peripheral neuropathy. Thirty-two healthy volunteers, 20 patients with type I diabetes and 30 patients with type II diabetes were studied in a clinical neurophysiology setting. Luminance (VEPs) and chromatic visual evoked potentials (CVEPs) were recorded, with white-black, grey-black, red-green and blue-yellow sinusoidal gratings. The peak latencies of the VEP positive wave and CVEP negative wave were recorded. Ten patients with type I and 8 with type II diabetes had peripheral neuropathy. VEPs were slower in patients with type II diabetes and CVEPs were slower in patients with type I and type II diabetes than in controls. Blue-yellow CVEPs were slower in type II than in type I diabetes. VEPs and red-green CVEPs were slower in patients with diabetes with neuropathy than in those without. In conclusion, we found that visual system impairment differs in diabetes with and without peripheral neuropathy.

Hyperphosphorylation of the hepatitis C virus NS5A protein requires an active NS3 protease, NS4A, NS4B, and NS5A encoded on the same polyprotein.

The nonstructural protein NS5A of hepatitis c virus (HCV) has been demonstrated to be a phosphoprotein with an apparent molecular mass of 56 kDa. In the presence of other viral proteins, p56 is converted into a slower-migrating form of NS5A (p58) by additional phosphorylation events. In this report, we show that the presence of NS3, NS4A, and NS4B together with NS5A is necessary and sufficient for the generation of the hyperphosphorylated form of NS5A (p58) and that all proteins must be encoded on the same polyprotein (in cis). Kinetic studies of NS5A synthesis and pulse-chase experiments demonstrate that fully processed NS5A is the substrate for the formation of p58 and that p56 is converted to p58. To investigate the role of NS3 in NS5A hyperphosphorylation, point and deletion mutations were introduced into NS3 in the context of a polyprotein containing the proteins from NS3 to NS5A. Mutation of the catalytic serine residue into alanine abolished protease activity of NS3 and resulted in total inhibition of NS5A hyperphosphorylation, even if polyprotein processing was allowed by addition of NS3 and NS4A in trans. The same result was obtained by deletion of the first 10 or 28 N-terminal amino acids of NS3, which are known to be important for the formation of a stable complex between NS3 and its cofactor NS4A. These data suggest that the formation of p58 is closely connected to HCV polyprotein processing events. Additional data obtained with NS3 containing the 34 C-terminal residues of NS2 provide evidence that in addition to NS3 protease activity the authentic N-terminal sequence is required for NS5A hyperphosphorylation.

Probing the conformational state of apomyoglobin by limited proteolysis.

We show here that limited proteolysis can probe the structural and dynamic differences between the holo and apo form of horse myoglobin (Mb). Initial nicking of the polypeptide chain of apoMb (153 amino acid residues, no disulfide bonds) by several proteases (subtilisin, thermolysin, chymotrypsin and trypsin) occurs at the level of chain segment 89-96. In contrast, holoMb is resistant to proteolytic digestion when reacted under identical experimental conditions. Such selective proteolysis implies that the F-helix of native holoMb (residues 82 to 97) is disordered in apoMb, thus enabling binding and adaptation of this chain segment at the active site of the proteolytic enzymes for an efficient peptide bond fission. That essentially only the F-helix in apoMb is largely disrupted was earlier inferred from spectroscopic measurements and molecular dynamics simulations. The results of this study provide direct experimental evidence for this and emphasize therefore that limited proteolysis is a useful and reliable method for probing structure and dynamics of proteins, complementing other experimental techniques such as NMR and X-ray crystallography.

Charge selectivity of proteinuria in type I diabetes explored by Ig subclass clearance.

To investigate the role of protein charge in early diabetic proteinuria, the clearance of proteins differing in charge and/or size (anionic and cationic Igs, albumin) was evaluated in 98 insulin-dependent (type I) diabetic patients selected as a representative sample of the 418 patients attending our clinics. Of the patients, 12.9% were microalbuminuric and 4.8% were macroalbuminuric. Anionic and total IgG clearances were significantly increased in 30.6 and 12.2% of patients and were correlated with duration of disease. Anionic IgG4 clearances were increased in patients (9.2%) with normal IgG excretion, suggesting that charge-selectivity impairment is responsible for protein loss. Anionic Ig clearances were also higher in some patients (14.3%) with normal albumin clearance, probably as a result of different glomerular filtration and/or tubular reabsorption. The anionic-cationic IgG clearance ratio tended to increase in parallel with albumin clearance, but once above macroalbuminuric levels, it tended to fall again, indicating the concomitant presence of size-selectivity loss. The anionic IgG clearance and the anionic-cationic IgG ratio, in addition to albumin excretion, may be valuable in assessing early kidney protein charge-selectivity impairment and better characterizing normoalbuminuric patients and those in the preclinical stage of diabetic nephropathy.

Soluble and insoluble dietary fibre in diabetic diets.

The possibility of modulating postprandial metabolic responses in diabetics by an increase in the amount of soluble fibre rather than by the use of the high amounts of total dietary fibre (DF), so far strongly advocated, was investigated. Soluble and insoluble DF components of common foodstuffs were analysed and the data utilized to formulate three different meals with similar quantities of available carbohydrate, protein and fat and differing only in the quantity and quality of DF: low fibre (LF), high soluble fibre (HSF) and high insoluble fibre (HIF). Ten NIDDM patients in good metabolic control received each test meal in randomized order at 2-week intervals. The postprandial blood glucose and serum insulin responses to the LF and HIF test meals were similar. The HSF meal produced significantly lower glucose (P less than 0.001) and insulin (P less than 0.05) responses, compared to either LF or HIF meals. Such results may be of relevance in the formulation of diabetic diets in order to prevent an excess of insoluble fibre, so improving patients' compliance. Fruits and vegetables may be used advantageously to increase quantities of soluble fibre, limiting excesses of legumes or guar additives.

Food fiber choices for diabetic diets.

The use of dietary fiber (DF) in the diet of diabetics, although recommended, is often prevented by a limited tolerance and/or by the high cost and unpalatability of fiber supplements. Knowing that only or mainly the water soluble fraction of DF is effective in modulating postprandial hyperglycemia, the DF content (soluble, insoluble, and total) of a variety of common foodstuffs was determined. Such data were then utilized in the formulation of two complete meals, isocaloric and isoglucidic, characterized by a high-soluble, low-soluble, and total fiber content. The meals were administered to 13 NIDDM patients in good metabolic control. The data confirmed a significant reduction (p less than 0.001) of postprandial hyperglycemia and a moderate less significant reduction of insulinemia after the high fiber meal.

Clinical trial with porcine des-Phe B1 insulin. A comparative study with unmodified insulin on therapeutical efficacy, biological activity and immunogenicity.

Studies have been carried out in insulin-dependent diabetics of porcine Des-pheB1 insulin, which is an insulin analogue obtained by removal of the N-terminal aminoacid of the B chain. The therapeutic activity of Des-phe insulin (regular and semilinte preparations) was tested in a group of 24 insulin-dependent diabetics and compared with the unmodified parent compound. Both types of insulin, Des-phe and unmodified were chromatographically purified preparations. The mean daily blood glucose profile obtained with Des-phe insulin was slightly higher than that of unmodified preparations, while the mean blood glucose and the "M" index of Schlichtkrull were similar. The biological activity of regular Des-phe and its unmodified parent compound was evaluated in 6 further insulin-dependent diabetics, with the aid of an artificial endocrine pancreas. The insulin requirement to achieve an optimal metabolic control was 10% less with Des-phe insulin than with the unmodified preparation. The immunogenicity of Des-phe and unmodified insulins, tested by measuring plasma insulin antibody titres in diabetic patients either newly or already insulin treated, was comparable. However the binding capacity of 125I-Des-phe insulin to preexisting antibodies seemed to be less than that of unmodified 125I-insulin in patients previously treated with unmodified insulin. Finally Des-phe appeared able to correct promptly and completely the insulin-induced lipodystrophy of three insulin-dependent diabetics.