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P Castellino

Publications and source records attributed to P Castellino.

At least 19 recordsLinked to original sources
PubMed2006

Global approach to cardiovascular risk in chronic kidney disease: reality and opportunities for intervention.

The current implementation into nephrology clinical practice of guidelines on treatment of cardiovascular (CV) risk factors in chronic kidney disease (CKD) is unknown. We designed a cross-sectional analysis to evaluate the prevalence and treatment of eight modifiable CV risk factors in 1058 predialysis CKD patients (stage 3: n=486; stage 4: n=430, stage 5: n=142) followed for at least 1 year in 26 Italian renal clinics. The median nephrology follow-up was 37 months (range: 12-391 months). From stages 3 to 5, hypertension was the main complication (89, 87, and 87%), whereas smoking, high calcium-phosphate product and malnutrition were uncommon. The prevalence of proteinuria (25, 38, and 58%), anemia (16, 32, and 51%) and left ventricular hypertrophy (51, 55, and 64%) significantly increased, while hypercholesterolemia was less frequent in stage 5 (49%) than in stages 4 and 3 (59%). The vast majority of patients received multidrug antihypertensive therapy including inhibitors of renin-angiotensin system; conversely, diuretic treatment was consistently inadequate for both frequency and dose despite scarce implementation of low salt diet (19%). Statins were not prescribed in most hypercholesterolemics (78%), and epoietin treatment was largely overlooked in anemics (78%). The adjusted risk for having a higher number of uncontrolled risk factors rose in the presence of diabetes (odds ratio 1.29, 95% confidence interval 1.00-1.66), history of CV disease (odds ratio 1.48, 95% confidence interval 1.15-1.90) and CKD stages 4 and 5 (odds ratio 1.75, 95% confidence interval 1.37-2.22 and odds ratio 2.85, 95% confidence interval 2.01-4.04, respectively). In the tertiary care of CKD, treatment of hypertension is largely inadequate, whereas therapy of anemia and dyslipidemia is frequently omitted. The risk of not achieving therapeutic targets is higher in patients with diabetes, CV disease and more advanced CKD.

Aged↗
PubMed2001

Effects of insulin and amino acids on leucine metabolism in young and middle-aged humans.

BACKGROUND: Aging is characterized by loss of muscle mass. In healthy subjects this process is associated with hormone and nutritional changes which take place over many decades. Aim of the study To investigate the effects of insulin and amino acids on amino acid metabolism in middle-aged humans. METHODS: We evaluated leucine kinetics by means of the intravenous infusion of [1-(14C)]leucine, in 8 young (age 24 +/- 2 yr, BMI 21+/- 2 kg/M2) and in 6 middle-aged (age 53 +/- 4 yr, BMI 26 +/- 1 kg/M2) healthy subjects. Studies were performed under fasting conditions (basal), and after 180 min of euglycemic hyperinsulinemic clamp (study I), or 180 min of euglycemic hyperinsulinemia in combination with an intravenous amino acid infusion (study II). RESULTS: In the basal state endogenous leucine flux (ELF, an index of proteolysis), normalized for IBW, averaged 1.71 +/- 0.12 and 1.66 +/- 0.14 micromol/kg x min in young and middle-aged subjects, respectively. Basal leucine oxidation (0.22 +/- 0.03 vs 0.28 +/- 0.03 micromol/ kg x min, p < 0.05) was lower in middle-aged with respect to young subjects. Non-oxidative leucine disposal (NOLD, an index of protein synthesis: 1.44 +/- 0.11 vs 1.43 +/- 0.11 micromol/kg x min) was similar in young and middle-aged subjects, respectively. In response to insulin (study I) the absolute and percent decline of ELF and LOX were similar in young and middle-aged subjects: ELF declined to 1.05 +/- 0.06 micromol/kg x min (-39 +/- 5 %) and 1.07 +/- 0.14 micromol/kg x min (-36 +/- 4%), in young and middle-aged, respectively (both p < 0.01 vs basal); LOX declined to 0.21 +/- 0.02 micromol/kg min (-35 +/- 3 %), and 0.18 +/- 0.05 micromol/kg x min (-28 +/- 3%, p < 0.05 vs basal) in young and middle-aged individuals respectively (both p < 0.01 vs basal). In contrast, insulin-mediated whole-body glucose uptake was lower in middle-aged subjects (6.6 +/- 1.4 mg/ kg x min) with respect to young individuals (8.1+/-1.7 mg/kg min, p < 0.05). During study II (insulin plus AA) a significant rise in NOLD was obtained in both young (1.72 +/- 0.10 micromol/kg x min, p < 0.01 vs basal) and middle-aged subjects (1.76 +/- 0.25 micromol/kg x min, p < 0.01 vs basal). Similarly, net leucine balance rose significantly in both young (+0.62 +/- 0.13 vs -0.25 +/- 0.02 micromol/kg x min, p < 0.01 vs basal) and middle-aged subjects (+0.37 +/- 0.08 vs -0.22 +/- 0.03 micromol/ kg x min, p < 0.01 vs basal) suggesting that the anabolic response to amino acids is preserved in middle-aged subjects. CONCLUSIONS: In middle-aged subjects we observed 1) a moderate decline in basal leucine oxidation; 2) a normal antiproteolytic response to insulin and a reduction in glucose uptake; and 3) a normal anabolic response to AA plus insulin. In conclusion, the data provide evidence for a normal regulation of protein anabolism and an early dissociation between the metabolic effects of insulin on glucose uptake and proteolysis in middle-aged subjects.

Adult↗
PubMed2001

Effects of dietary protein restriction on fibrinogen and albumin metabolism in nephrotic patients.

BACKGROUND: Nephrotic syndrome (NS) is characterized by profound changes in albumin and fibrinogen levels. Dietary protein restriction has been advocated in the treatment of patients with NS, but its effects on albumin and fibrinogen metabolism have not been fully elucidated. METHODS: We evaluated the effects of dietary protein restriction on endogenous leucine flux (ELF), fibrinogen and albumin metabolism in seven patients with NS who consumed either a normal protein diet (NPD; 1.20 +/- 0.06 g/kg/day), or a low protein diet (LPS; 0.66 +/- 0.04 g/kg/day) for four weeks. Seven normal subjects served as controls. The postabsorptive ELF value, fractional synthesis rate (FSR) and absolute synthesis rate (ASR) of both albumin and fibrinogen were evaluated during the last 120 minutes of a five-hour 5,5,5-D3-L-leucine infusion. RESULTS: During the NPD regimen. ELF was increased, serum albumin was reduced, plasma fibrinogen was increased, albumin FSR and ASR were both increased, fibrinogen FSR was normal, and fibrinogen ASR was greater in patients with NS compared to controls. In patients with NS the LPD regimen reduced proteinuria, ELF, albumin FSR and ASR, plasma fibrinogen levels, fibrinogen ASR, and increased serum ulbumin levels. Dietary-induced changes in albumin and fibrinogen synthesis were significantly correlated (r = 0.719, P < 0.05). CONCLUSIONS: Patients with NS treated with LPD show: (1) a reduction of proteinuria, albumin ASR and FSR, with an increase in serum albumin levels and its intravascular pool; (2) a decrease of fibrinogen ASR, with a reduction in both plasma fibrinogen levels and intravascular pool; and (3) a reduced rate of whole body proteolysis.

Adult↗
PubMed2001

Circulating natriuretic peptide concentrations in patients with end-stage renal disease: role of brain natriuretic peptide as a biomarker for ventricular remodeling.

OBJECTIVES: To determine levels of natriuretic peptides (NPs) in patients with end-stage renal disease (ESRD) and to examine the relationship of these cardiovascular peptides to left ventricular hypertrophy (LVH) and to cardiac mortality. PATIENTS AND METHODS: One hundred twelve dialysis patients without clinical evidence of congestive heart failure underwent plasma measurement of NP concentrations and echocardiographic investigation for left ventricular mass index (LVMI). RESULTS: Plasma atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) concentrations correlated positively with LVMI and inversely with left ventricular ejection fraction, whereas C-type NP and Dendroaspis NP levels did not correlate with LVMI. In dialysis patients with LVH (LVMI >125 g/m2), plasma ANP and BNP concentrations were increased compared with those in dialysis patients without LVH (both P<001). In a subset of 15 dialysis patients without LVH or other concomitant diseases, plasma BNP concentrations were not significantly increased compared with those in 35 controls (mean +/- SD, 20.1+/-13.4 vs 13.5+/-9.6 pg/mL; P=.06), demonstrating that the BNP concentration was not increased by renal dysfunction alone. Furthermore, the BNP level was significantly higher in the 16 patients who died from cardiovascular causes compared with survivors (mean +/- SD, 129+/-13 vs 57+/-7 pg/mL; P<.003) and was significantly associated with greater risk of cardiovascular death in Cox regression analysis (P<.001), as was the ANP level (P=.002). CONCLUSIONS: Elevation of the plasma BNP concentration is more specifically related to LVH compared with the other NP levels in patients with ESRD independent of congestive heart failure. Thus, BNP serves as an important plasma biomarker for ventricular hypertrophy in dialysis patients with ESRD.

Adolescent↗
PubMed2000

Differential effects of amino acid and ketoacid on protein metabolism in humans.

We examined the effects of insulin, amino acid (AA), and branched-chain ketoacid (KA) availability on leucine kinetics in eight healthy volunteers (age = 22 +/- 2 y, body mass index = 24 +/- 1 kg) by using the euglycemic insulin clamp and [1-14C] leucine turnover techniques. Four experimental conditions were studied: study I, hyperinsulinemia; study II, hyperinsulinemia with maintenance of basal plasma AA and branched-chain KA concentrations; study III, hyperinsulinemia with hyperaminoacidemia and basal plasma branched-chain KA concentrations; and study IV, hyperinsulinemia plus basal plasma AA concentrations and elevated branched-chain KA levels. Basal endogenous leucine flux (ELF) averaged 1.20 +/- 0.05 (mumol.kg-1.min-1, mean +/- SE); basal leucine oxidation (LOX) was 0.25 +/- 0.01; and basal non-oxidative leucine disposal (NOLD) was 0.95 +/- 0.04. ELF significantly decreased in study I (0.77 +/- 0.06 mumol.kg-1.min-1, P < 0.01 versus basal). When plasma AA and branched-chain KA were either maintained at their basal levels (study II) or increased above baseline values (studies III and IV), ELF declined further (0.64 +/- 0.05, 0.66 +/- 0.02, and 0.66 +/- 0.03 mumol.kg-1.min-1, respectively; all Ps < 0.01 versus basal and P < 0.01 versus study I). LOX declined in study I (0.12 +/- 0.02 mumol.kg-1.min-1, P < 0.01 versus basal) but increased significantly in studies II, III, and IV (0.31 +/- 0.04, 0.37 +/- 0.03, and 0.40 +/- 0.03 mumol.kg-1.min-1, respectively, all Ps < 0.01 versus basal, P < 0.05 study IV versus study II, and P < 0.05 study III versus study II). NOLD declined in study I (0.65 +/- 0.05 mumol/kg.min, P < 0.01 versus basal), whereas neither the maintenance of basal plasma AA/branched-chain KA levels (study II; 0.89 +/- 0.2 mumol.kg-1.min-1) nor the elevation of plasma branched-chain KA concentration (study IV; 0.96 +/- 0.1 mumol.kg-1.min-1) increased NOLD above baseline level. A stimulation of NOLD was observed only when plasma AA levels were increased (study III; 1.23 +/- 0.03 mumol/kg.min, P < 0.01 versus basal). In conclusion, the present data do not support the concept of a direct anabolic action of ketoanalogs but do provide additional evidence for the pivotal role of AA availability in the stimulation of whole-body protein synthesis.

Adult↗
PubMed2000

Impaired glucose oxidation and glucose-induced thermogenesis in renal transplant recipients.

BACKGROUND: Renal transplant recipients often show various metabolic abnormalities including reduced glucose tolerance, impaired insulin sensitivity and altered lipid metabolism. However, the acute effects of carbohydrate ingestion on substrate utilization and energy expenditure have not been fully elucidated. METHODS: We evaluated: (i) basal energy expenditure (EE) and substrate utilization, (ii) metabolic fate of an oral glucose load, and (iii) substrate-induced thermogenesis in: (a) 15 non-diabetic renal transplant recipients (Tx) (BMI 25+/-1) on triple immunosuppressive therapy, (b) 11 patients with primary glomerulonephritis (BMI 25+/-1) (Cort) receiving prednisone treatment, and (c) 12 healthy subjects (BMI 26+/-1) (N). Continuous indirect calorimetry was performed in the basal post-absorptive state for 60 min and continued for an additional 180 min following an oral glucose load (75 g). RESULTS: In the basal state, EE was similar in the three study groups. It averaged 14.6+/-0.7, 15.7+/-1.3, and 14.1+/-0.8 cal/kg/min in Tx, Cort, and N respectively. Glucose oxidation was higher in N (1.3+/- 0.2 mg/kg/min) than in Tx (0.7+/-0.2) and Cort (1.0+/-0.2) (P<0.05 in N vs. Tx and vs. Cort), whereas lipid oxidation was lower in N (0.6+/-0.1 mg/kg/min) than in Tx (0.9+/-0.1) and Cort (0.9+/-0.05) (P<0.03 in N vs. Tx and vs. Cort). After glucose ingestion, total carbohydrate oxidation averaged 21.2+/-2, 31.0+/-3, and 29.6+/-3 g, which represented 28+/-3, 41+/-3 and 39+/-2% of the total glucose load in Tx, Cort and N respectively (P<0.01 Tx vs Cort and N). The cumulative increase of EE (180 min) was 9.7+/-2, 13.2+/-3 and 13+/-3 kcal in Tx, Cort, and N respectively. CONCLUSIONS: The present data show that in non-diabetic renal transplant recipients basal EE is normal. However, basal lipid oxidation is higher and glucose oxidation is lower than in healthy subjects. In addition, the oxidative disposal of a glucose load and substrate-induced thermogenesis are impaired.

Administration, Oral↗
PubMed1999

Effects of insulin and amino acids on glucose and leucine metabolism in CAPD patients.

This study investigates the basal and insulin-stimulated glucose metabolism, substrate utilization, and protein turnover in eight patients maintained on continuous ambulatory peritoneal dialysis (CAPD) (mean age 39+/-5 yr, body mass index [BMI] 108+/-6) and 14 control subjects (mean age 33+/-4 yr, BMI 103+/-3). Euglycemic insulin clamp studies (180 min) were performed in combination with continuous indirect calorimetry and 1-14C leucine infusion (study I). Postabsorptive glucose oxidation was higher (1.75+/-0.18 versus 1.42+/-0.14 mg/kg per min) and lipid oxidation was lower (0.43+/-0.09 versus 0.61+/-0.12 mg/kg per min) in CAPD patients than in control subjects (P<0.05 versus control subjects). During the last 60 min of euglycemic hyperinsulinemia, the total rate of glucose metabolism was similar in CAPD and control subjects (6.33+/-0.51 versus 6.54+/-0.62 mg/kg per min). Both insulin-stimulated glucose oxidation (2.53+/-0.27 versus 2.64+/-0.37 mg/kg per min) and glucose storage (3.70+/-0.48 versus 3.90+/-0.58 mg/kg per min) were similar in CAPD and control subjects. Basal leucine flux (an index of endogenous proteolysis) was significantly lower in CAPD patients than in control subjects (1.21+/-0.15 versus 1.65+/-0.07 micromol/kg per min). Leucine oxidation (0.13+/-0.02 versus 0.26+/-0.02 micromol/kg per min) and nonoxidative leucine disposal (an index of protein synthesis) (1.09+/-0.16 versus 1.35+/-0.05 micromol/kg per min) were also reduced in CAPD compared with control subjects (P<0.01 versus control subjects). In response to insulin (study I), endogenous leucine flux decreased to 0.83+/-0.08 and 1.05+/-0.05 micromol/kg per min in CAPD and control subjects, respectively (all P<0.01 versus basal). Leucine oxidation declined to 0.06+/-0.01 and to 0.19+/-0.02 micromol/kg per min in CAPD and control subjects, respectively (P<0.01 versus basal). A second insulin clamp was performed in combination with an intravenous amino acid infusion (study II). During insulin plus amino acid administration, nonoxidative leucine disposal rose to 1.23+/-0.17 and 1.42+/-0.09 micromol/kg per min in CAPD and control subjects, respectively (both P<0.05 versus basal, P = NS versus control subjects), and leucine balance, an index of the net amino acid flux into protein, become positive in both groups (0.30+/-0.05 versus 0.40+/-0.07 micromol/kg per min in CAPD and control subjects, respectively) (both P<0.01 versus basal, P = NS versus control subjects). In summary, in CAPD patients: (1) basal glucose oxidation is increased; (2) basal lipid oxidation is decreased; (3) insulin-mediated glucose oxidation and storage are normal; (4) basal leucine flux is reduced; (5) the antiproteolitic action of insulin is normal; and (6) the anabolic response to insulin plus amino acid administration is normal. Uremic patients maintained on CAPD treatment show a preferential utilization of glucose as postabsorptive energy substrate; however, their anabolic response to substrate administration and the sensitivity to insulin are normal.

Adult↗
PubMed1998

Derangements in protein metabolism induced by type I diabetes mellitus.

In poorly controlled diabetics, the whole-body protein flux is increased by 20-30% in comparison to well-controlled type I diabetes (IDDM) and normal subjects. Intensive insulin administration completely reverses these abnormalities. In poorly controlled IDDM, the primary effect of insulin administration is to reduce the increased protein catabolic rate by suppressing the accelerated rate of protein breakdown. Studies in humans have demonstrated that the increased rate of protein synthesis observed in these patients is the consequence of elevated plasma amino acid levels. When IDDM subjects develop renal complications, a protein-restricted diet may be recommended to preserve the remnant kidney function. However, it has been demonstrated that in IDDM patients, metabolic adaptation to protein restriction is incomplete because suppression of endogenous proteolysis is impaired. Since this component of protein metabolism is very sensitive to insulin action, maintaining strict metabolic control during the protein restriction regimen has been suggested. The major studies on the effects of amino acid and insulin on protein metabolism in patients with diabetes mellitus are reviewed.

Amino Acids↗
PubMed1997

Na+/Li+ and Na+/H+ countertransport activity in hypertensive non-insulin-dependent diabetic patients: role of insulin resistance and antihypertensive treatment.

We measured erythrocyte Na+/Li+ and Na+/H+ countertransport (CT) activity (millimoles per liter per cell per hour) in 10 healthy control subjects (age, 38 +/- 4 years; body mass index, 25 +/- 1 kg/m2) and in 25 hypertensive patients with non-insulin-dependent diabetes mellitus ([NIDDM] age, 49 +/- 3 years; body mass index, 29 +/- 1 kg/m2; fasting plasma glucose, 157 +/- 12 mg/dL) 4 weeks after discontinuation of previous antihypertensive treatment. Na+/Li+ CT was significantly increased in hypertensive NIDDM patients compared with controls (0.56 +/- 0.04 v 0.30 +/- 0.03, P < .01), whereas Na+/H+ CT was similar to control levels (21 +/- 1 v 20 +/- 2). A positive correlation was found between Na+/Li+ CT and the severity of insulin resistance (r = .69, P < .01), mean arterial pressure ([MAP] r = .64, P < .01), plasma triglyceride concentration (r = .46, P < .05), and plasma total cholesterol (r = .41, P < .05). An inverse correlation was found between Na+/Li+ CT activity and plasma insulin concentration (r = -.47, P < .05). No relationship was observed between Na+/Li+ CT activity and either creatinine clearance or proteinuria. Stepwise multiple regression analysis for all metabolic variables and blood pressure showed that only the severity of insulin resistance was positively correlated with increased Na+/Li+ CT activity. Na+/H+ and Na+/Li+ CT activity were not altered by 3 hours of euglycemic physiologic hyperinsulinemia (84 +/- 3 microU/mL). Hypertensive NIDDM subjects were treated for 3 months with captopril, nifedipine, or doxazosin. After captopril, a reduction of Na+/H+ CT was observed (22 +/- 4 v 13 +/- 2, P < .05); Na+/Li+ CT decreased after doxazosin (0.56 +/- 0.06 v 0.45 +/- 0.05, P < .05) and nifedipine (0.52 +/- 0.06 v 0.42 +/- 0.05, P < .05). In conclusion, in hypertensive NIDDM subjects, (1) Na+/Li+ CT is increased and is correlated with the level of insulin resistance and the MAP; (2) acute physiologic hyperinsulinemia does not affect Na+/Li+ or Na+/H+ CT activity; and (3) Na+/H+ CT activity is reduced by captopril, and Na+/Li+ CT is decreased by doxazosin and nifedipine.

Adult↗
PubMed1997

Correlation between amino acid induced changes in energy expenditure and protein metabolism in humans.

The relationship between energy expenditure and protein metabolism during amino acid (AA) administration was evaluated in normal humans. A balanced AA solution was infused for 180 min at five different rates: 20 (study I), 40 (study II), 80 (study III), 160 (study IV), and 240 mg.m2(-1).min-1 (study V), on separate days, in seven normal, overnight-fasted subjects (age 25 +/- 2 y; height 172 +/- 5 cm; weight 68 +/- 4 kg). Indirect calorimetry and [1-14C] leucine infusion techniques were employed. Basal total plasma AA concentration averaged 1827 +/- 121 mumol/L and increased to 2192 +/- 142, 2576 +/- 158, 3677 +/- 195, 5638 +/- 237, and 7185 +/- 261 mumol/L in studies I-V, respectively. Basal energy expenditure averaged 0.60 +/- 0.02 kcal.m2(-1).min-1 and increased slightly in studies I and II (to 0.62 +/- 0.03, 0.63 +/- 0.02, respectively), and significantly in studies III-V (to 0.65 +/- 0.03, 0.70 +/- 0.04, and 0.77 +/- 0.05 kcal.m2(-1).min-1, respectively, all P < 0.01 versus basal; P < 0.05-0.01 for each study versus preceding study). Basal nonoxidative leucine disposal (NOLD), an index of protein synthesis, averaged 73 +/- 3 mumol.m2(-1).min-1 and increased, albeit not significantly, in studies I and II (to 75 +/- 5, 76 +/- 4, respectively). In contrast, a significant increase in NOLD was observed in studies III-V (to 87 +/- 7, 103 +/- 7, and 127 +/- 9 mumol.m2(-1).min-1, respectively; all P < 0.01 versus basal; P < 0.05-0.01 for each study versus preceding study). Basal respiratory quotient averaged 0.81 +/- 0.02 and did not change significantly in studies I-V (0.80 +/- 0.02, 0.79 +/- 0.02, 0.80 +/- 0.03, 0.82 +/- 0.02 and 0.82 +/- 0.03, respectively). The thermic effect of AA administration, calculated as percent of the AA energy infused, was constant and averaged 24 +/- 4, 19 +/- 3, 17 +/- 4, 17 +/- 3, and 18 +/- 3% in studies I-V, respectively. When AA-induced increase in protein synthesis was plotted with the increment in energy expenditure, a positive correlation was obtained (r = 0.792, P < 0.001). In summary, during AA administration (1) the absolute rise in energy expenditure is dose-dependent and does not show evidence of achieving a plateau; (2) it is positively correlated with AA-induced protein synthesis; and (3) the thermic effect is not dependent upon the AA dose administered. The data provide a quantitative assessment of AA-induced thermogenesis in normal humans and the energy needs associated with an acute stimulation of protein synthesis.

Adult↗
PubMed1997

Protein metabolism in human obesity: relationship with glucose and lipid metabolism and with visceral adipose tissue.

It is controversial whether metabolic disorders of human obesity include protein metabolism. Even less information is available concerning the effect of fat distribution on protein metabolism. Therefore, a comprehensive evaluation of glucose, lipid, and protein metabolism was performed in 11 obese nondiabetic and 9 normal women whose body composition and regional fat distribution were determined. [1-14C]Leucine and [3-3H]glucose were infused in the postabsorptive state and during an euglycemic hyperinsulinemic (35-40 microU/mL) clamp combined with indirect calorimetry for assessment of leucine flux, oxidation, and nonoxidative disposal, glucose turnover and oxidation, and lipid oxidation. Fat-free mass (FFM) was estimated by a bolus of 3H2O. Subcutaneous abdominal and visceral adipose tissues were determined by nuclear magnetic resonance imaging. During the clamp, obese women had lower glucose turnover (4.51 +/- 0.41 vs. 6.63 +/- 0.40 mg/min.kg FFM; P < 0.05), with a defect in both oxidation (3.27 +/- 0.22 vs. 3.89 +/- 0.21) and nonoxidative disposal (1.24 +/- 0.27 vs. 2.74 +/- 0.41; P < 0.005), whereas lipid oxidation was higher during the clamp (0.49 +/- 0.15 vs. 0.17 +/- 0.09 mg/min.kg FFM). There was no difference in leucine flux (basal, 2.23 +/- 0.17 vs. 2.30 +/- 0.29; clamp, 2.06 +/- 0.19 vs. 2.10 +/- 0.24 mumol/min.kg FFM), oxidation (basal, 0.37 +/- 0.04 vs. 0.36 +/- 0.05; clamp, 0.34 +/- 0.04 vs. 0.39 +/- 0.06) and nonoxidative leucine disposal (basal, 1.86 +/- 0.17 vs. 1.94 +/- 0.26; clamp, 1.72 +/- 0.20 vs. 1.71 +/- 0.19) in the two groups. In obese women, basal leucine oxidation was directly related with glucose oxidation and inversely to lipid oxidation (both P < 0.05), whereas visceral adipose tissue was inversely related to leucine flux both in the basal state and during the clamp (P < 0.05). In conclusion, in human obesity, 1) rates of protein metabolism in the basal state and in the range of insulin concentrations encountered after a meal are normal; 2) protein oxidation is positively related to glucose oxidation and negatively related to lipid oxidation; and 3) visceral adipose tissue is inversely related to all parameters of protein metabolism.

Adipose Tissue↗
PubMed1996

Renal hemodynamics in renal transplant recipients. The role of reduced kidney mass and cyclosporine administration.

It has been hypothesized that both the cyclosporine (CsA) treatment and the reduction of renal mass may affect the renal hemodynamic regulation in kidney transplant recipients. To address this question, we evaluated the renal hemodynamic response to hyperaminoacidemia (i.v. mixed amino acid infusion 3.3 mg/kg/minute for 150 minutes) in four study groups: (1) 16 renal transplant recipients (Tx), (2) 6 uninephrectomized (Nx) subjects, (3) 7 subjects treated with CsA for chronic uveitis (CsA), and (4) 9 normal controls (NC). In response to amino acid administration (AA), glomerular filtration rate (GFR) rose significantly in NC subjects (80 +/- 6 vs. 91 +/- 6 ml/minute; P<0.01) and Nx patients (57 +/- 3 vs. 68 +/- 7 ml/minute; P<0.01) and failed to increase in Tx recipients (39 +/- 3 vs. 37 +/- 3 ml/minute) and CsA-treated patients (58 +/- 3 vs. 53 +/- 4 ml/minute). Renal plasma flow (RPF) did not change in Tx recipients (243 +/- 27 vs. 235 +/- 25 ml/minute) but rose significantly in all other groups (257 +/- 17 vs. 344 +/- 33 in NX, 364 +/- 6l vs. 441 +/- 55 in CsA, 412 +/- 49 vs. 472 +/- 72 ml/min in NC subjects; P<0.05 vs. basal). Basal renal vascular resistances were significantly higher in Tx (0.29 +/- 0.04 mmHg/mlxmin; P<0.01 vs. all other groups) than in Nx (0.21 +/- 0.01 mmHg/mlxmin), CsA (0.23 +/- 0.04 mmHg/mlxmin) (both P<0.01 vs. NC subjects), and NC subjects (0.13 +/- 0.02 mmHg/mlxmin). Renal vascular resistance failed to decline in Tx (0.31 +/- 0.04 mmHg/mlxmin) during AA infusion but declined significantly in all other groups. In Tx, basal GFR was positively correlated to renal allograft volume (r=0.547, P<0.03); however, no relationship was found between the latter and basal RPF or the AA induced changes in GFR. In summary, the present study demonstrates that in kidney transplant recipients and in CsA-treated subjects, the renal functional reserve to hyperaminoacidemia is impaired. This is at variance to what is observed in normal controls and uninephrectomized subjects. In renal transplant recipients, basal but not amino acid stimulated GFR correlates with renal allograft volume. We conclude that basal GFR is related to renal volume in Tx and that the response to hyperaminoacidemia seems to be affected by chronic CsA administration.

Adult↗
PubMed1996

Correlation between glomerular morphology and renal haemodynamic response to amino-acid administration in patients with IgA nephropathy.

RATIONALE: To establish relationship, if any, between renal morphology and renal haemodynamic response to amino acids. DESIGN AND METHODS: We investigated the correlation between renal haemodynamic regulation and morphology in a group of 15 patients with primary IgA nephropathy (IgAN) (age 26 +/- 2 years, BMI 24.4 +/- 1, GFR 64 +/- 5 ml/min, RPF 377 +/- 34 ml/min, FF 0.17 +/- 0.02). Twelve normal subjects (age 30 +/- 3 years, BMI 24 +/- 1, GFR 82 +/- 6 ml/min, RPF 421 +/- 42 ml/min, FF 0.19 +/- 0.02) were studied as controls. IgA patients were divided into two groups according to the histological staging of glomerular lesions: group I (n = 7) stage II, and group II (n = 8) stage III-IV. RESULTS: In the basal state GFR was similar in the two groups and averaged 64 +/- 9 and 64 +/- 6 ml/min respectively. In contrast, FF was significantly lower in group II (0.14 +/- 0.01) (P < 0.05) in comparison to group I (0.21 +/- 0.03) and controls (0.19 +/- 0.02). In order to evaluate the renal functional reserve, all study groups underwent to an intravenous amino-acid infusion designed to increase plasma amino acid levels twofold (total from 2096 +/- 145 to 4301 +/- 221 mumol/l in IgA nephropathy patients and from 2272 +/- 83 to 3844 +/- 238 mumol/l in controls). In response to amino-acid infusion, GFR rose significantly in group I (GFR 20 +/- 2% and RPF 37 +/- 4% versus basal) and controls (GFR 20 +/- 2% and RPF 20 +/- 3% versus basal) (both P < 0.01 vs basal). In contrast, in patients with more severe glomerular lesions (group II) neither GFR nor RPF rose significantly (GFR -1 +/- 4% and RPF -8 +/- 6% versus basal) (P NS versus basal, P < 0.01 versus group I and controls). CONCLUSIONS: The data show that in IgA nephropathy: severe forms of glomerular lesions are associated with a complex alteration of glomerular haemodynamic regulation, characterized by lower basal FF and loss of haemodynamic response to hyperaminoacidaemia.

Adult↗
PubMed1996

Insulin and hyperaminoacidemia regulate by a different mechanism leucine turnover and oxidation in obesity.

Seven normal glucose-tolerant obese subjects [ideal body weight (IBW) = 161%] and 18 controls (IBW = 102%) were studied with the euglycemic insulin clamp (10 and 40 mU.m-2.min-1) technique, [14C]leucine infusion, and indirect calorimetry to examine if the insulin resistance with respect to glucose metabolism extends to amino acid/protein metabolism. In the basal state, total plasma amino acid and leucine concentrations, endogenous leucine flux (ELF), leucine oxidation (LO), and nonoxidative leucine disposal (NOLD) were similar in obese and control subjects. During both low (10 mU.m-2.min-1)- and higher (40 mU.m-2.min-1)-dose insulin clamp studies, insulin-mediated glucose uptake was reduced in obese vs. control subjects (P < 0.01). During the last hour of the higher-dose insulin clamp step, the decrease in total plasma amino acids, branched-chain amino acids, and leucine concentration was impaired in obese vs. control subjects (P < 0.01). However, suppression of ELF and NOLD was similar in both groups. During the low-dose insulin clamp, the decrease in plasma leucine concentration, LO, and ELF all were impaired (P < 0.01). A second study was performed in which the total plasma amino acid concentration was increased two- to threefold in both groups. Under these conditions of low plasma insulin/high amino acid levels, LO and NOLD increased similarly in obese and control subjects. In conclusion, insulin resistance is a common feature of both glucose and protein metabolism in obesity. The defect in protein metabolism is characterized by an impairment of the ability of insulin to inhibit proteolysis; the stimulatory effect of hyperaminoacidemia on protein synthesis is intact in obesity.

Adult↗
PubMed1996

Effect of alpha-adrenergic blockers, ACE inhibitors, and calcium channel antagonists on renal function in hypertensive non-insulin-dependent diabetic patients.

In the present study we investigated the effect of a selective alpha 1-adrenergic blocker (doxazosin), an angiotensin-converting enzyme (ACE) inhibitor (captopril), and a calcium channel antagonist (nifedipine) on renal function in hypertensive non-insulin-dependent diabetic patients. 30 NIDD hypertensive patients (age = 50 +/- 3 years; BMI = 30 +/- 1 kg/m2) (mean +/- SEM) were studied before and after a 12-week period of antihypertensive treatment. Ten patients were treated with doxazosin (Cardura) (2-8 mg once daily or 8 mg b.i.d.), 9 with captopril (Capoten) (25-50 mg b.i.d.), and 11 with nifedipine (Procardia-XL) (30-60 mg once daily). Blood pressure, creatinine clearance, 24-hour urinary protein excretion, fasting plasma glucose concentration and glycosylated hemoglobin were measured before and after drug treatment. Fasting plasma glucose and glycosylated hemoglobin (HbA1c) were similar in all three groups prior to the start of antihypertensive therapy and did not change significantly from baseline in any treatment groups. In the doxazosin group creatinine clearance rose from 99 +/- 8 to 122 +/- 8 ml/1.73 m2.min (p < 0.01), while 24-hour urinary protein excretion declined from 2.66 +/- 0.05 to 1.76 +/- 0.02 mg/day/ml/1.73 m2.min (p < 0.01). In diabetics treated with captopril creatinine clearance rose from 93 +/- 6 to 109 +/- 9 ml/1.73 m2.min (p < 0.05), while the 24-hour urinary protein excretion fell from 2.70 +/- 0.05 to 2.03 +/- 0.04 mg/day/ml/1.73 m2.min (p < 0.05). In patients treated with nifedipine creatinine clearance did not change (97 +/- 6 vs. 94 +/- 7 ml/1.73 m2.min), while 24-hour urinary protein excretion decreased from 2.84 +/- 0.04 to 1.95 +/- 0.03 mg/day/ml/1.73 m2.min. Systolic and diastolic blood pressure were similar in doxazosin (150 +/- 3/95 +/- 2 mm Hg), captopril (153 +/- 3/93 +/- 1), and nifedipine (155 +/- 4/93 +/- 1) groups prior to the start of antihypertensive therapy and declined to 143 +/- 3/84 +/- 3 (doxazosin), 139 +/- 3/82 +/- 3 (captopril), and 141 +/- 3/84 +/- 1 (nifedipine) mm Hg (all p < 0.01 vs. pretreatment). In summary, both doxazosin and captopril treatment were associated with significant rises in GFR, while all three antihypertensive agents caused a significant decline in proteinuria. These results indicate that alpha-adrenergic blockers, ACE inhibitors, and calcium channel antagonists can safely and effectively be used in the clinical management of non-insulin-dependent diabetic patients with hypertension.

Adrenergic alpha-Antagonists↗
PubMed1996

Differential responsiveness of protein synthesis and degradation to amino acid availability in humans.

We investigated the effects of graded hyperaminoacidemia on protein metabolism in eight healthy, young (25 +/- 2 years), normal weight (BMI = 25 +/- 1 kg/m2), overnight-fasted human subjects. A balanced amino acid solution was infused for 180 min at five different rates: 0.5 (study I), 1.0 (study II), 2.0 (study III), 4.0 (study IV). and 6.0 (study V) mg x kg-1 x min-1 on separate days in random order. Studies were performed with [1-14C]leucine infusion and indirect calorimetry to calculate leucine oxidation (LOX), nonoxidative leucine disposal (NOLD) (an index of protein synthesis), and endogenous leucine flux (ELF) (an index of proteolysis). Basal total plasma amino acid concentrations averaged 1.85 +/- 0.1 mmol/l and increased to 2.27 +/- 0.1, 2.70 +/- 0.2, 3.84 +/- 0.2, 5.87 +/- 0.4, and 7.52 +/- 0.3 mmol/l in studies I-V, respectively. ELF decreased from a basal value of 2.27 +/- 0.2 to 2.12 +/- 0.2, 1.97 +/- 0.1, 1.73 +/- 0.2, 1.67 +/- 0.3, and 1.65 +/- 0.1 micromol x kg-1 x min-1 in studies I-V, respectively (P < 0.05 for study I vs. basal, P < 0.01 for studies II-V vs. basal, and NS for studies IV and V vs. study III). LOX increased from a basal value of 0.31 +/- 0.04 to 0.38 +/- 0.05, 0.41 +/- 0.02, 0.64 +/- 0.04, 1.11 +/- 0.07, and 1.56 +/- 0.05 micromol x kg-1 x min-1 in studies I-V (all P < 0.01 vs. basal; P < 0.05-0.01 for each study vs. preceding study). Basal NOLD averaged 1.96 +/- 0.2 and did not change significantly in studies I and II (2.03 +/- 0.2 and 2.10 +/- 0.1 micromol x kg-1 x min-1). In contrast, a significant increase in NOLD was observed in studies III, IV, and V (to 2.3 +/- 0.15, 2.74 +/- 0.2, and 3.25 +/- 0.7 micromol x kg-1 x min-1, respectively; all P < 0.01 vs. basal; P < 0.05-0.01 for each study vs. preceding study). The net leucine balance (difference between ELF and NOLD)(-0.31 +/- 0.06 micromol x kg-1 x min-1) became less negative in study I (P < 0.01 vs. basal) and positive during studies II-V when the rise in plasma total amino acid levels was >/= 50% above basal level (P < 0.01 vs. each preceding study). In conclusion, NOLD, ELF, and LOX exhibit a differential responsiveness to acute changes in substrate availability: 1) small increments (25-50%) in plasma amino acid levels inhibit ELF and stimulate LOX but have no effect on NOLD; 2) stimulation of NOLD is observed only with increments in plasma amino acid levels >/= 100% above basal values; and 3) increments in plasma amino acid concentrations > 100% above basal values cause a progressive dose-related increase in LOX and NOLD but do not induce any further inhibition of ELF.

Adult↗
PubMed1995

Comparison of the effects of human recombinant insulin-like growth factor I and insulin on plasma amino acid concentrations and leucine kinetics in humans.

We examined the effects of recombinant human insulin-like growth factor I (IGF-I) and insulin on the plasma amino acid (AA) profile and leucine kinetics in eight normal subjects. IGF-I was infused at 52 pmol.kg-1.min-1, in combination with prime-continuous [1-14C] leucine infusion, to obtain steady-state plasma concentrations of total (54 +/- 3 nmol/l) and free (7.3 +/- 1 nmol/l) IGF-I (study 1). In response to IGF-I, plasma AA levels declined by 37 +/- 3% (1975 +/- 198 to 1368 +/- 120 mumol/l) and total branched chain amino acids (BCAA) declined by 34 +/- 3% (390 +/- 21 to 256 +/- 13 mumol/l). This hypoaminoacidaemic effect was associated with a decline in endogenous leucine flux of 17 +/- 2% (1.88 +/- 0.05 to 1.57 +/- 0.04 mumol.kg-1.min-1) and leucine oxidation of 17 +/- 1% (0.31 +/- 0.02 vs 0.26 +/- 0.02 mumol.kg-1.min-1) (both p < 0.01 vs basal). The same subjects underwent a second study (study 2) in which insulin was infused at 6.22 pmol.kg-1.min-1 to obtain a steady-state plasma insulin concentration of 530 +/- 25 pmol/l while maintaining euglycaemia. The infusion rate was designed to match the declines in plasma BCAA levels and leucine turnover observed during IGF-I infusion. The rates of glucose infusion necessary to maintain euglycaemia during IGF-I and insulin infusion were 4.9 +/- 1.0 and 7.8 +/- 0.6 mg.kg-1.min-1, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗