Elevated diet-induced thermogenesis and lipid oxidation rate in Crohn disease

BACKGROUND

Although malnutrition is frequently observed in Crohn disease (CD), its cause is not clear. Regulation of energy metabolism and diet-induced thermogenesis (DIT) have not been adequately studied in CD.

OBJECTIVE

The aim was to study DIT and substrate oxidation in patients with inactive ileal CD.

DESIGN

After a test meal providing 50.2 kJ/kg body wt, DIT was assessed by indirect calorimetry performed over 360 min in 18 CD patients and 12 healthy volunteers matched for age, sex, weight, and height. Body composition was evaluated with the labeled-water-bolus injection technique.

RESULTS

Fat-free mass did not differ significantly between groups, but CD patients had markedly lower fat mass than control subjects (13.8+/-5.63 compared with 19.0+/-3.49 kg; P < 0.001). Nonprotein respiratory quotient was lower in CD patients than control subjects (0.80+/-0.04 compared with 0.86+/-0.03; P < 0.001). Average respiratory quotient between 75 and 150 min after the test meal was 0.85+/-0.03 in CD patients and 0.91+/-0.02 in control subjects (P < 0.001). Lipid oxidation rate was higher in CD patients than in control subjects (2.26+/-1.13 compared with 1.50+/-0.75 kJ/min; P < 0.05). DIT was higher in CD patients than in control subjects (9.89+/-1.93% compared with 5.67+/-0.91% of energy intake; P < 0.001).

CONCLUSIONS

Patients with inactive ileal CD had significantly higher DIT and lipid oxidation rate than do healthy volunteers. These results may explain why CD patients have difficulty maintaining adequate nutritional status, and the findings also suggest that a diet relatively rich in fat may attain better energy balance.

L-carnitine improves glucose disposal in type 2 diabetic patients

OBJECTIVE

Aim of the present study is to evaluate the effects of L-carnitine on insulin-mediated glucose uptake and oxidation in type II diabetic patients and compare the results with those in healthy controls.

DESIGN

Fifteen type II diabetic patients and 20 healthy volunteers underwent a short-term (2 hours) euglycemic hyperinsulinemic clamp with simultaneous constant infusion of L-carnitine (0.28 micromole/kg bw/minute) or saline solution. Respiratory gas exchange was measured by an open-circuit ventilated hood system. Plasma glucose, insulin, non-esterified fatty acids (NEFA) and lactate levels were analyzed. Nitrogen urinary excretion was calculated to evaluate protein oxidation.

RESULTS

Whole body glucose uptake was significantly (p<0.001) higher with L-carnitine than with saline solution in the two groups investigated (48.66+/-4.73 without carnitine and 52.75+/-5.19 micromoles/kg(ffm)/minute with carnitine in healthy controls, and 35.90+/-5.00 vs. 38.90+/-5.16 micromoles/kg(ffm)/minute in diabetic patients). Glucose oxidation significantly increased only in the diabetic group (17.61+/-3.33 vs. 16.45+/-2.95 micromoles/kg(ffm)/minute, p<0.001). On the contrary, glucose storage increased in both groups (controls: 26.36+/-3.25 vs. 22.79+/-3.46 micromoles/kg(ffm)/minute, p<0.001; diabetics: 21.28+/-3.18 vs. 19.66+/-3.04 micromoles/kg(ffm)/minute, p<0.001). In type II diabetic patients, plasma lactate significantly decreased during L-carnitine infusion compared to saline, going from the basal period to the end-clamp period (0.028+/-0.0191 without carnitine and 0.0759+/-0.0329 with carnitine, p<0.0003).

CONCLUSIONS

L-carnitine constant infusion improves insulin sensitivity in insulin resistant diabetic patients; a significant effect on whole body insulin-mediated glucose uptake is also observed in normal subjects. In diabetics, glucose, taken up by the tissues, appears to be promptly utilized as fuel since glucose oxidation is increased during L-carnitine administration. The significantly reduced plasma levels of lactate suggest that this effect might be exerted through the activation of pyruvate dehydrogenase, whose activity is depressed in the insulin resistant status.

Glucose metabolism and insulin sensitivity in inactive inflammatory bowel disease

BACKGROUND

Inflammatory mediator concentration was found to be increased in active inflammatory bowel disease, and this could be related to an insulin-resistant state. Moreover, glucocorticoids, which are widely used in the treatment of inflammatory bowel disease, are notoriously related to insulin resistance.

AIM

To measure body composition, whole body glucose uptake and oxidation in Crohn's disease and ulcerative colitis patients with inactive disease.

METHODS

All patients had clinical, ultrasound and biochemical assessment. Body composition was determined by isotopic dilution technique; basal metabolic rate and substrate oxidation were measured by indirect calorimetry. Insulin sensitivity was assessed by the euglycaemic hyperinsulinaemic clamp. Ten patients with inactive Crohn's disease (five males, aged 31.1 +/- 7.0 years) and 10 patients with inactive ulcerative colitis (five males, aged 33.4 +/- 8.8 years) participated in the study. Forty healthy subjects, matched for age and height were used as a control group.

RESULTS

Crohn's disease patients showed lower BMI (P < 0.001), fat mass (P < 0.05) and respiratory quotient (P < 0.001) values compared to both ulcerative colitis and control subjects. No difference in peripheral glucose uptake (micromol/kg/min) was found between groups (respectively 42.5 +/- 6.78 in Crohn's disease, 40.2 +/- 8.00 in ulcerative colitis and 41.4 +/- 10.8 in control subjects). Glucose storage and oxidation did not differ between groups.

CONCLUSION

Our data showed that inflammatory bowel disease patients in a remission phase of the disease activity had a whole body glucose uptake and oxidation similar to those of control subjects, probably due to fat-free mass preservation and low blood and tissue cytokine concentration.

Effect of disease localization on the anthropometric and metabolic features of Crohn's disease

OBJECTIVE

We conducted this study to evaluate the effect of disease localization on the anthropometric and metabolic characteristics of inactive Crohn's disease (CD).

METHODS

Forty-three patients with biopsy or radiology proven CD (23 men; age, 33.8 yr; range, 18-54 yr) in clinical remission (simplified Crohn's diseases activity index [SCDAI] < 3) and not receiving steroid therapy or nutritional support were enrolled in the study. Patients were separated into three subgroups according to disease localization: ileal (n = 16), ileo-colonic (n = 13), and colonic CD (n = 14). Sixty healthy volunteers (26 men; age, 32.0 yr; range, 18-60 yr), matched for age and height were used as control subjects. Body composition was assessed by both anthropometry and bioimpedance analysis and indirect calorimetry was performed to measure energy expenditure and substrate oxidation rates.

RESULTS

CD patients showed a lower body weight than controls, both as a whole (61.5 kg; range, 41.5-74.0 vs 66.9 kg; range, 55.0-86.0 kg; p < 0.001) and separated by disease localization (ileal; p < 0.001; ileo-colonic; p < 0.001; and colonic; p < 0.05 vs controls). Fat-free mass (FFM) did not differ between the groups, whereas fat mass was significantly lower in CD patients than in controls (p < 0.001), with the lowest values in ileal and ileo-colonic patients. Basal metabolic rate by kg of FFM was higher in CD patients than in healthy individuals (p < 0.01). Nonprotein respiratory quotient was significantly lower in CD than in controls as a whole (0.79; range, 0.73-0.84 vs 0.83; range, 0.79-0.89; p < 0.001) or separated by disease localization (p < 0.001 each subgroup vs controls), with a consequent higher lipid oxidation rate. A lower dietary lipid intake was found in patients than in controls (p < 0.01).

CONCLUSIONS

Regardless of disease localization, CD patients showed a lower fat mass and a higher utilization of lipids than control subjects. Patients with ileal and ileo-colonic disease showed the greater reduction in body weight, compared with control subjects, suggesting they were at a higher risk of malnutrition, probably as a consequence of the simultaneous occurrence of both malabsorption and decreased energy intake.

Three months of abstinence from alcohol normalizes energy expenditure and substrate oxidation in alcoholics: a longitudinal study

OBJECTIVE

The aim of this study was to evaluate the energy expenditure, substrate oxidation, and body composition in alcoholics during addiction and after several months of abstinence.

METHODS

A total of 32 alcoholics without liver cirrhosis and malabsorption were consecutively recruited. A total of 55 social drinkers, matched for gender and height, were studied as a control group. Anthropometry and bioimpedance analysis were performed to assess body composition, and indirect calorimetry was used to measure basal metabolic rate (BMR) and substrate oxidation. Total abstinence was then achieved in 15 subjects. At 1, 2, 3, and 6 months of abstinence, the metabolic variables and the energy intake were re-examined.

RESULTS

At enrollment (T0) alcoholics compared to controls showed a significant decrease in body mass index (22.2+/-2.71 vs 23.6+/-1.3 kg/m2; p < 0.05), fat mass (14.1+/-4.5 vs 16.7+/-3.3 kg; p < 0.01), an increased BMR normalized by fat-free mass (34.5+/-3.7 vs 32.1+/-2.01 kcal/kg/day; p < 0.01), a lower nonprotein respiratory quotient (npRQ: 0.76+/-0.03 vs 0.83+/-0.03; p < 0.001), with a consequently higher lipid oxidation (0.08+/-0.02 vs 0.04+/-0.02 g/min; p < 0.01), and a lower carbohydrate oxidation (0.05+/-0.02 vs 0.10+/-0.03 g/min; p < 0.01). Although at 1 and 2 months of abstinence the metabolic parameters had improved, only after 3 months of abstinence did alcoholics show values of body mass index (23.2+/-2.6 kg/ m2), fat mass (17.0+/-5.34 kg), BMR/fat-free mass (33.1+/-2.78 kcal/kg/day), npRQ (0.82+/-0.02), lipid oxidation (0.05+/-0.03 g/min) and carbohydrate oxidation (0.11+/-0.04 g/min) comparable to those of controls; these values remained constant at 6 months.

CONCLUSION

Three months of abstinence from alcohol could represent the minimum time necessary to obtain a normalization of the metabolic variables considered and of the nutritional status for these patients, probably related to a regression of the functional alterations of the microsomal ethanol oxidizing system and of mitochondria secondary to chronic ethanol abuse.

Influence of chronic alcohol abuse on body weight and energy metabolism: is excess ethanol consumption a risk factor for obesity or malnutrition?

OBJECTIVES

To evaluate the influence of chronic alcohol abuse on body composition and energy metabolism in patients affected by chronic alcoholism (group A) compared with a group of healthy social drinkers (group B).

SETTING

A university hospital clinic in Italy.

SUBJECTS

A total of 32 alcoholics without clinical or laboratory signs of liver cirrhosis and malabsorption.

MEASUREMENTS

Body composition was assessed by anthropometric measurements. Resting energy expenditure (REE) and substrate oxidation rate was measured by indirect calorimetry. Daily caloric intake was computed on the basis of a food diary compiled over 7 days.

RESULTS

Alcoholics showed a significantly lower body weight (P < 0.05) and a significant lower fat mass (P < 0.05) compared with controls. A higher waist-to-hip ratio was found in group A than in group B, both as a whole group (P < 0.01) or separated by gender (females, P < 0.01) and males, P < 0.001), indicating a prevalence of fat distribution in the abdominal region in alcoholics. REE was significantly higher in group A than in group B (P < 0.05). The non-protein respiratory quotient was significantly lower in group A than in group B (P < 0.001) with a consequent higher utilization of lipids (P < 0.01) and a lower carbohydrate oxidation (P < 0.05) in group A. The energy intake provided only by food ingestion was found to be significantly higher in group B (P < 0.01), whilst the total caloric intake, computed as food intake plus alcohol intake, was higher in group A (P < 0.01).

CONCLUSIONS

Alcoholics, as compared with social drinkers, showed a lower body weight due essentially to a fat mass reduction, a higher REE value normalized by fat-free mass, and a preferential utilization of lipids as energy substrate. These findings might suggest that chronic ethanol abuse is able to determine an impairment of nutritional status due, at least in part, to an alteration of the substrate oxidation.

Genetic epidemiology of cholesterol cholelithiasis among Chilean Hispanics, Amerindians, and Maoris

BACKGROUND & AIMS

The etiology of cholesterol gallstones is multifactorial, with interactions of genes and the environment. The hypothesis that aborigine cholesterol lithogenic genes are widely spread among Chileans, a population with a high prevalence of gallstones, was tested.

METHODS

Medical history and anthropometric measurements were obtained and abdominal ultrasonography was performed in 182 Mapuche Indians, 225 Maoris of Easter Island, and 1584 Hispanics. Blood groups, DNA, lipids, and glucose were analyzed. The Amerindian Admixture Index and mitochondrial DNA (mtDNA) assessed the ethnicity and degree of racial admixture.

RESULTS

Amerindian Admixture Index was 0.8 in Mapuches and 0.4 in Hispanics. All Mapuches, 88% of Hispanics, but none of Maoris had Amerindian mtDNA haplotypes. Age- and sex-adjusted global prevalence of gallstone disease was higher in Mapuches (35%) than in Hispanics (27%) and Maoris (21%). Compared with Hispanics, the youngest group of Mapuches had the greatest corrected risk of gallstones: odds ratios of 6.0 in women and 2.3 in men. In contrast, the gallstone risk in Maoris was lower compared with Hispanics: odds ratios of 0.6 for women and 0.5 for men.

CONCLUSIONS

Cholesterol lithogenic genes appear widely spread among Chilean Indians and Hispanics. They could determine the early formation of gallstones and explain the high prevalence of gallbladder diseases among some South American populations.

Cholestatic hepatitis due to ticlopidine: clinical and histological recovery after drug withdrawal. Case report and review of the literature

A 72-year-old housewife presented with clinical and laboratory signs of acute cholestatic hepatitis. Symptoms had appeared 6 months after she was started on ticlopidine 250 mg/day. Infectious aetiologies were excluded by serology and there was no history of alcohol abuse or use of other drugs. Clinical findings were confirmed by liver biopsy. The drug was discontinued and symptoms gradually subsided. A second biopsy obtained during this phase documented complete resolution of the hepatic damage. A review of the literature shows that the late onset of hepatic toxicity in this case is unique and this is the first report to include histological documentation during the acute phase and after recovery.

Metabolic features of inflammatory bowel disease in a remission phase of the disease activity

OBJECTIVES

To evaluate the anthropometric and metabolic characteristics of patients with Crohn's disease (CD) and ulcerative colitis (UC), comparing both groups with healthy volunteers.

DESIGN

A cross-sectional study.

SETTING

The Department of Internal Medicine, Catholic University Hospital, Rome, Italy.

SUBJECTS

Thirty-four patients with biopsy-proven inflammatory bowel disease (18 CD; 16 UC) in clinical remission (SCDAI < 3 and Powell-Tuck index < 4) not receiving steroid therapy.

INTERVENTIONS

All patients had a clinical examination.

MAIN OUTCOME MEASURES

Blood indicators of inflammation and nutritional status. Body composition was assessed by both anthropometry and bioimpedance and metabolic variables were measured by indirect calorimetry over a 60-90 min period.

RESULTS

CD had a lower body weight than both controls (58.1 kg, range 41.5-71.0 vs. 66.4 kg, range 57.0-76.0; P < 0.001) and UC) 58.1 kg, range 41.5-71.0 vs. 69.6 kg, range 50.5-94.0; (P < 0.001). Fat-free mass (FFM) did not differ between the groups, whilst fat mass was significantly lower in CD than in UC (P < 0.05) and controls (P < 0.001). Normalizing the basal metabolic rate by FFM, a higher value was found in CD compared with UC (143 kJ kg-1) d-(-1), range 97.5-179 vs. 133 kJ kg-1 d-1, range 123-148; P < 0.05) and control subject 143 kj kg-1 d-1, range 97.5-179 vs. 134 kj kg-1 d-1, range 122-162; P < 0.05). The nonprotein respiratory quotient was significantly lower in CD compared to UC 0.80, range 0.73-0.84 vs. 0.84, range 0.79-0.91; P < 0.01) and controls (0.80, range 0.73-0.84 vs. 0.83, range 0.81-0.87; P < 0.001), with a consequently higher lipid oxidation rate in CD.

CONCLUSIONS

CD subjects showed a decreased fat mass and enhanced utilization of lipids compared with UC and controls. These data could be explained by the larger intestinal involvement and considered as a contribution to lipid tissue wasting in CD.

A surgical option for familial chylomicronemia associated with insulin-resistant diabetes mellitus

BACKGROUND

The goal of the present work is to present an effective surgical approach for the treatment of a medically-resistant form of hyperlipidemia.

METHODS

Two siblings with familial lipoprotein-lipase deficiency and subsequent hyperchylomicronemia, widespread skin xanthomas and severe insulin-resistant diabetes mellitus came to our observation after several unsuccessful attempts at medical treatment. In order to lower plasma lipids through lipid malabsorption, a modified bilio-pancreatic diversion operation was employed. The rationale in deciding to use this surgical approach was based also on the likely hypothesis that diabetes, in these subjects, was secondary to high circulating and tissue levels of lipids. Insulin sensitivity in the two treated subjects, as well as in 24 healthy volunteers constituting the control group, was assessed by euglycemic hyperinsulinemic clamp and indirect calorimetry, obtaining total end-clamp glucose uptake (M) and end-clamp glucose oxidation (ECGO) rates.

RESULTS

Within 3 weeks of surgery, plasma triglycerides and cholesterol levels had decreased from 4500 and 500 mg/dl (with dietary restrictions) to lower than 450 and 150 mg/dl (on a free, lipid-rich diet) respectively. Fasting plasma glucose levels had decreased from above 300 (under daily repeated subcutaneous injections of insulin) to 80-100 mg/dl (without administration of insulin or oral hypoglycemic agents). Body weight and fat free mass were maintained in both subjects after surgery. In both patients, before surgery M and ECGO were significantly lower than in normal subjects, while after surgery they were not significantly different from normal subjects, confirming the positive metabolic effect of the operation.

CONCLUSION

The surgical option used in these patients may represent an interesting and effective new possibility for treatment of those severe cases of hyperlipemia leading otherwise to metabolic complications and a low quality of life.

The metabolic effect of dodecanedioic acid infusion in non-insulin-dependent diabetic patients

Dodecanedioic acid (C12) is an even-numbered dicarboxylic acid (DA). Dicarboxylic acids are water-soluble substances with a metabolic pathway intermediate to those of lipids and carbohydrates. Previous studies showed that contrary to other DAs, very low amounts of C12 are lost with urine. The effects of 46.6 mmol of C12 intravenous infusion for 195 min on blood glucose levels were investigated in five patients with non-insulin-dependent diabetes mellitus (NIDDM), with a good metabolic compensation, and in five healthy volunteers matched for gender, age, and body mass index. Blood samples were taken every 15 min for a period of 360 min to measure glucose, insulin, C-peptide, ketone bodies, and free fatty acid (FFA) levels, and 24-h urine samples were collected to measure C12 and urea excretion. Plasma and urinary C12 concentrations were determined by high-pressure liquid chromatography (HPLC). Indirect calorimetry was continuously performed both basally and during the study period. The average 24-h urinary excretion of C12 was 6.5% versus 6.7% of the administered dose, respectively, in NIDDM patients and in healthy controls. The area under the curve (AUC) values of plasma C12 were 279.9 +/- 42.7 mumol in NIDDM patients and 219.7 +/- 14.0 mumol in controls (P = ns). Plasma glucose levels significantly decreased in NIDDM patients during C12 infusion (from 7.8 +/- 0.6 to 5.4 +/- 0.8 mM at the end of the study period, P < 0.05). Lactate plasma concentration decreased in NIDDM patients from 3.5 +/- 0.2 to 1.5 +/- 0.1 mM (P < 0.001), whereas blood pyruvate increased at the end of the experimental session from 26.0 +/- 11.6 to 99.5 +/- 14.9 microM (P < 0.01). Free fatty acids decreased in diabetic patients from the beginning until the end of C12 infusion, although this difference did not reach statistical significance. No significant increase was found between basal and final values in VO2 consumption and in the values of nonprotein respiratory quotient in both groups of subjects examined. The experimental data indicate that C12 infusion decreases plasma glucose levels in NIDDM patients to normal range without influencing plasma insulin levels. The balance between pyruvate and lactate was affected by C12 infusion only in diabetics patients. C12 might represent a fuel substrate immediately available for tissue energy requirements, especially in conditions such as diabetes mellitus in which glucose metabolism is impaired.

Daily energy and substrate metabolism in patients with cirrhosis

Twenty-four-hour energy expenditure (EE) and substrate oxidation (respiratory chamber), and whole-body glucose uptake and oxidation rates (euglycemic hyperinsulinemic clamp [EHC] and indirect calorimetry) were measured in 10 male patients with posthepatitis, Child B cirrhosis, and 8 healthy male controls matched for age, body size, and body composition. Twenty-four-hour EE was higher in cirrhotic patients than in controls (8,567 +/- 764 vs. 6,825 +/- 507 kJ/d; P < .001). Resting energy expenditure (REE) was also higher in cirrhotic patients than in controls (7,881 +/- 1,125 vs. 5,868 +/- 489 kJ/d; P < .01). Twenty-four-hour respiratory quotient (RQ) (trend) and fasting RQ (0.76 +/- 0.05 vs. 0.82 +/- 0.04; P < .05) were lower in cirrhotic patients than in controls, reflecting higher lipid oxidation rates in the former group. Whole-body glucose uptake was markedly reduced in cirrhotic patients when compared with controls (22.4 +/- 3.2 vs. 44.5 +/- 7.6 mmol/kg/min; P < .001). Carbohydrate oxidation rates, computed during the last 40 minutes of the clamp, were 8.5 +/- 1.1 mmol/kg/min in cirrhotic patients and 22.6 +/- 6.1 mmol/kg/min in controls (P < .001). Nonoxidative glucose disposal was 13.9 +/- 2.5 mmol/kg/min in cirrhotic patients and 22.0 +/- 5.5 mmol/kg/min in normal controls (P < .01). In conclusion, our data indicate that patients with Child B cirrhosis who still maintain a nutritional status (i.e., body composition) comparable with healthy controls are characterized by a cluster of metabolic defects that include hypermetabolism, increased lipid utilization, and insulin resistance. This suggests that the above metabolic syndrome precedes and probably leads to malnutrition in the natural history of the liver disease. In fact, in spite of the absence of a significant difference in caloric intake between cirrhotic patients and normal controls, the elevated 24-hour EE might allow for a relevant weight loss in cirrhotic patients, because, with time, the differences may be cumulative. However, whether this hypermetabolism can lead to a real weight loss remains to be evaluated in a longitudinal study.

Twenty-four-hour energy balance in Crohn disease patients: metabolic implications of steroid treatment

Several hypotheses have been proposed to explain the nutritional deficiencies seen in Crohn disease patients, including inadequate food intake, decreased assimilation and increased loss of nutrients, and increased energy expenditure. To assess the effect of steroid therapy on body composition, energy expenditure, and fuel selection in Crohn disease, we compared 12 patients (6 men and 6 women) with biopsy-proven ileal Crohn disease with 11 healthy volunteers (6 men and 5 women). Five patients [Crohn's disease activity index (CDAI) = 98.4 +/- 3.78] took no medication and seven patients (CDAI = 283.9 +/- 22.5) were administered 29 +/- 18 mg prednisone/d. Body composition was evaluated by isotopic dilution and bioelectrical impedance analysis, and 24-h energy expenditure and basal metabolic rate were measured in a respiratory chamber. Fat-free mass was not significantly different among groups, whereas fat mass was lower in patients than in control subjects. Energy intake was higher in treated patients than in both untreated patients (P = 0.004) and control subjects (P = 0.005). Fecal losses were not significantly different between untreated patients and control subjects, but were higher (and proportional to the CDAI) in treated patients than in control subjects (P = 0.001). Metabolizable energy was not significantly different among groups, whereas energy balance was significantly higher in treated patients than in both control subjects (P = 0.0057) and untreated patients (P = 0.018). Nitrogen balance was mildly negative in treated patients compared with both control subjects and untreated patients, but not significantly so. In conclusion, prednisone treatment in Crohn disease patients stimulates food intake, promoting an overall positive energy balance despite large fecal nutrient losses.

Differences in metabolic variables between adult coeliac patients at diagnosis and patients on a gluten-free diet

BACKGROUND

Coeliac patients often have nutrient malabsorption with nutritional status impairment, but no report on their energy requirements is available. In this study body composition, dietary habits, basal energy expenditure, and substrate oxidation were investigated in patients with the classic form of coeliac disease.

METHODS

Sixteen untreated and 18 adult coeliac patients on a gluten-free diet participated in the study. Body composition was assessed by anthropometry and bioimpedance. Energy expenditure was measured by indirect calorimetry. A food diary over 7 days was collected.

RESULTS

Coeliac patients showed reduced body weight components but not a different fat-free mass percentage compared with age- and sex-matched healthy volunteers. Basal metabolic rate normalized by fat-free mass (BMR/FFM) was higher in coeliac patients than in controls. Untreated patients showed a significantly higher non-protein respiratory quotient with regard to both treated patients (P < 0.01) and controls (P < 0.05), an increased percentage of carbohydrate intake, and a good correlation between lipid faecal loss and carbohydrate oxidation (Spearman R = 0.74; P < 0.01).

CONCLUSIONS

Both groups of patients had lower fat mass and FFM content than controls. The preferential carbohydrate oxidation in untreated patients might be a result of both lipid malabsorption and high carbohydrate intake.

Dodecanedioic acid infusion induces a sparing effect on whole-body glucose uptake, mainly in non-insulin-dependent diabetes mellitus

Even-numbered dicarboxylic acids (DA) have been proposed as an alternative fuel substrate in parenteral nutrition. In particular, dodecanedioic acid (C12) shows a rapid plasma clearance from tissues, a very low urinary excretion compared with other DA and a high oxidation rate. The aim of the present study was to investigate the effect of C12 infusion on insulin-stimulated glucose uptake in patients with non-insulin-dependent diabetes mellitus (NIDDM) compared with healthy volunteers. A primed-constant infusion of C12 (0.39 mmol/min) was administered over 240 min, and at 120 min a 2 h euglycaemic hyperinsulinaemic clamp was performed. Blood specimens were sampled every 30 min and fractioned urines were collected over 24 h. The levels of C12 were measured by HPLC. Indirect calorimetry was performed continuously during the entire session. Body composition was assessed in all subjects studied to obtain fat-free mass (FFM) values. Whole-body glucose uptake decreased significantly during C12 infusion in both groups, although this effect was much more evident (P < 0.01) in NIDDM patients (52.4 (SD 15.8) % decrease compared with saline) than in controls (25.9 (SD 12.1) % decrease). The M value (mumol/kgFFM per min) was reduced by C12 to lower levels in NIDDM patients than in normal controls (12.6 (SD 3.9) v. 25.9 (SD 4.5), P < 0.01). Urinary excretion of C12 over 24 h was significantly lower in NIDDM patients than in controls (4.26 (SD 0.30) mmol v. 5.43 (SD 0.48), P < 0.01), corresponding to less than 3% of the administered dose. The infusion of C12 decreased non-protein RQ significantly in both groups of patients. In conclusion, this study shows, for the first time, that C12 significantly reduces glucose uptake in both normal controls and NIDDM patients, although this sparing effect on glucose uptake is much more pronounced in diabetic patients. These data suggest that C12 decreases glucose uptake and oxidation, mainly through a mechanism of substrate competition. Thus, it might be a useful alternative substrate in enteral or parenteral nutrition, sparing glucose utilization and increasing glycogen stores, in those clinical conditions, like NIDDM, where reduced insulin-induced glucose uptake and oxidation are observed.

Binding of indole-3-acetic acid to human serum albumin and competition with L-tryptophan

Indole-3-acetic acid (IAA) is a product of tryptophan (Trp) metabolism and is found to be markedly increased in uremic sera. IAA binding to defatted human serum albumin at 37 degrees C and pH 5, 7.4, and 8.5 was studied by equilibrium dialysis, and data were analyzed assuming two independent high affinity binding sites plus a class of low affinity sites. The estimated values of the association constant of dominant site were: 7.96 x 10(3) M-1 at pH 5, 11.57 x 10(3) M-1 at pH 7.4, and 6.30 x 10(3) M-1 at pH 8.5. The competition between IAA and Trp for albumin binding at pH 7.4 was investigated. The results suggest that one specific albumin site is common for IAA and Trp, but the data were not adequately predicted by a purely competitive scheme. A better prediction was achieved assuming that the binding of IAA to a site different from the common site inhibits Trp binding.

Energy expenditure, substrate oxidation, and body composition in subjects with chronic alcoholism: new findings from metabolic assessment

There is some controversy as to the effect of ethanol on body weight and alcohol energy contribution to body mass. The aim of this study was to evaluate the effect of alcohol addiction on resting energy expenditure (REE) and body composition. Twelve patients with current alcoholism (A) without severe liver disease or lipid and carbohydrate malabsorption were compared with a group of healthy social drinkers (B) matched for sex, age, and height. Their caloric intake was computed on the basis of a food diary. REE was measured with indirect calorimetry, and body composition was assessed by both anthropometry and bioimpedance. A significant decrease in fat mass in A compared with B was found (14.8 +/- 5.39 vs. 19.0 +/- 3.50 kg; p < 0.05). No significant differences were observed in fat-free mass (FFM) or in total body water between the two groups. A showed higher REE values normalized by FFM than B (35.5 +/- 2.97 vs. 33.0 +/- 2.95 kcal/kgFFM; p < 0.05). The nonprotein respiratory quotient was significantly lower in A than in B (0.76 +/- 0.03 vs. 0.86 +/- 0.03; p < 0.001), and A showed significantly higher lipid oxidation and lower carbohydrate oxidation than B (p < 0.05). The daily caloric intake provided only by food ingestion was found to be significantly higher in controls, but because the percentage of alcohol calories of total energy intake was 46.3 +/- 6.80 in alcoholics and 13.6 +/- 3.59 in controls (p < 0.0001), the total caloric intake, computed as food intake plus alcohol intake, was higher in alcoholics than in control subjects. No statistical differences were found in urinary nitrogen excretion and fecal loss between groups. Patients with alcoholism showed an increased REE over predicted values and a preferential lipid oxidation with respect to controls; these findings could be related to induction of microsomal ethanol oxidizing system and to mitochondrial function adaptation secondary to chronic alcohol abuse. In either case, the effects of such changes in energy metabolism may contribute to alcohol associated hepatic injury.

Kinetics of dodecanedioic acid and effect of its administration on glucose kinetics in rats

Dodecanedioic acid (C12), a saturated aliphatic dicarboxylic acid with twelve C atoms, was given as an intraperitoneal bolus to male Wistar rats, with the aim of evaluating C12 suitability as an energy substrate for parenteral nutrition. The 24 h urinary excretion of C12 was 3.9% of the administered dose. C12 kinetics were investigated by a one-compartment model with saturable tissue uptake and reversible binding to plasma albumin. The analysis of plasma concentration and urinary excretion data from different animals yielded the population means of the kinetic parameters: renal clearance was 0.72 ml/min per kg body weight (BW) (much smaller than inulin clearance in the rat), and maximal tissue uptake was 17.8 mumol/min per kg BW corresponding to 123.7 J/min per kg BW. These results encourage the consideration of C12 as a possible substrate for parenteral nutrition. To investigate the effect of C12 administration on glucose kinetics, two other groups of rats, one treated with an intraperitoneal bolus of C12 and the other with saline, were subsequently given an intravenous injection of D[-U-14C]glucose in a tracer amount. Radioactivity data of both control and C12-treated rats were analysed by means of a two-compartment kinetic model which takes into account glucose recycling. The estimates of glucose pool size (2.3 mmol/kg BW) and total-body rate of disappearance (82.1 mumol/min per kg BW) in control rats agreed with published values. In C12-treated rats, the rate of disappearance appeared to be reduced to 36.7 mumol/min per kg BW and the extent of recycling appeared to be negligible.

Reversibility of insulin resistance in obese diabetic patients: role of plasma lipids

The aim of the present study was to measure whole body glucose uptake (M) and oxidation rate by euglycaemic hyperinsulinaemic clamp and indirect calorimetry in 7 morbidly obese subjects (BMI > 40 kg/m2) at three time points: before bilio-pancreatic diversion (BPD) surgery (Ob); 3 months after surgery POI; and after reaching stable body weight, at least 2 years after surgery POII. A group of 7 control subjects (C), matched groupwise for sex, age and BMI with POII patients, was also studied. The M value at POI was significantly higher than at Ob (49.12 +/- 8.57 vs 18.14 +/- 8.57 mumol.kg-1.min-1). No statistical difference was observed between the POII and C groups. Similarly, glucose oxidation rate was significantly increased at POI with respect to Ob (24.2 +/- 7.23 vs 9.42 +/- 3.91 mumol.kg-1.min-1) and was not significantly different between POII and C. Basal levels of non-esterified fatty acids (NEFA) decreased significantly both from Ob to POI and from POI to POII (1517.1 +/- 223.9 vs 1039.6 +/- 283.4 vs 616.0 +/- 77.6 mumol.1(-1). The same applied to basal plasma triglycerides (2.07 +/- 0.77 vs 1.36 +/- 0.49 vs 0.80 +/- 0.19 g.1(-1). Weight decreased mainly in the late postoperative period (POI to POII 124.28 +/- 11.22 to 69.71 +/- 11.78, 83% of total decrement), rather than in the early postoperative period (Ob to POI 135.25 +/- 14.99 to 124.28 +/- 11.22 kg, 17% of total decrement). We also report the clinical case of a young woman of normal weight, who underwent BPD for chylomicronaemia (secondary to familial lipoprotein lipase deficiency), whose M value, plasma insulin and blood glucose levels were normalized upon normalization of serum NEFA and triglyceride levels as determined by the therapeutic lipid malabsorption. In conclusion, in obese diabetic patients lipid malabsorption induced by BPD causes a definite enhancement of insulin sensitivity and glucose tolerance. This improvement in metabolism is noticeable before the surgery has major effects on body weight. These observations suggest that lowered plasma lipids, rather than weight loss per se, are the cause of the reversibility of insulin resistance.

Cochlear dysfunction in IDDM patients with subclinical peripheral neuropathy

OBJECTIVE

To investigate the function of the auditory pathway from the cochlea to the auditory cortex in subjects with IDDM.

RESEARCH DESIGN AND METHODS

Brain stem, middle-, and long-latency auditory-evoked responses and evoked otoacoustic emissions were measured in 48 normally hearing IDDM patients and in age- and sex-matched nondiabetic subjects. Peripheral neuropathy was diagnosed by nerve conduction velocity (NCV) at the peroneal and sural nerves. Auditory brain stem responses (ABRs) reflect auditory pathway function within the brain stem; middle-latency responses (MLRs) and long-latency responses (LLRs) originate from the auditory cortex; and evoked otoacoustic emissions (EOAEs) give objective information about preneural, mechanical elements of the cochlear function.

RESULTS

A subclinical peripheral neuropathy was found in 12 diabetic patients. We found higher latencies of waves I (t = 4.4, P < 0.0001), III (t = 3.7, P = 0.0004), and V (t = 2.7, P = 0.008) of ABRs in diabetic patients (I: 1.7 +/- 0.13 ms; III: 3.9 +/- 0.17 ms; V: 5.7 +/- 0.24 ms), compared with those of the control group (I: 1.6 +/- 0.13 ms; III: 3.7 +/- 0.18 ms; V: 5.6 +/- 0.17 ms). However, neither central transmission time (i.e., the wave interpeak I-V) nor MLRs and LLRs were found to be significantly different in diabetic and control subjects. Mean EOAE amplitude was found to be significantly reduced (F = 4.2, P = 0.02) in diabetic patients with a reduced NCV (7.6 +/- 3.9 dB; Scheffé test: P = 0.03), but not in those without neuropathy (9.1 +/- 4.2 dB), compared with the control group (10.8 +/- 3.1 dB). No correlations were found between duration of diabetes and EOAEs or between sural NCV and peroneal NCV and metabolic control. EOAEs were not correlated with peroneal and sural NCVs.

CONCLUSIONS

Our results indicate that the early preneural dysfunction of cochlear receptors causes a prolonged activation of the peripheral portion of the auditory pathway, while signal conduction along the central auditory pathway was shown to be normal in diabetes.