The threshold tracking nerve conduction study technique: Experience of clinical users unfamiliar with a research-grade neuronal excitability system

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Threshold tracking nerve conduction studies (TTNCSs) measure axon excitability.

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TTNCSs can objectively characterize neuronal dysfunction and treatment response.

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An available research-grade TTNCS system has not been widely implemented .

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Clinical electrophysiologists with varying levels of experience can perform TTNCSs.

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A user-friendly system and education about TTNCSs could broaden use of the technique.

Objective

To 1) explore if clinical electrophysiologists with different degrees of experience performing standard nerve conduction studies could run a threshold tracking nerve conduction study (TTNCS) protocol and 2) learn how clinical users view a research-grade TTNCSs neuronal excitability system.

Methods

Five clinical electrophysiologists conducted a TTNCS session using QTracS and then completed a questionnaire describing their impressions.

Results

All of the electrophysiologists completed the QTracS protocol on an initial attempt. Perceived strengths comprised the ease of preparatory steps and quick protocol speed. Identified drawbacks included an unwieldly user-interface. The electrophysiologists indicated that knowledge of TTNCS principles and applications would be critical for incorporation of the method into clinical use.

Conclusions

This pilot study suggests that clinical electrophysiologists can carry out TTNCSs with a research-grade system. The development of a more user-friendly program, along with dedicated education and training, could lead to wider application of the TTNCS technique.

Significance

Considered together with clinical presentation and other biomarkers, increased use of TTNCSs could provide improved assessment of neuromuscular disease and treatment response.

Influence of a new bicycle crank design on aerobic parameters of non-cyclists

AIM

A well known problem in conventional cycling crank systems is the pedalling dead spot when the crank arms are in vertical position. The pedalling dead spot mitigates the power output during the propulsion phase of pedalling. The aim of this study was to verify the effects of a new design of crank system on aerobic parameters of performance in healthy non-cyclists. The mechanical concept of the new system is based on the theory that crank arms should never be perpendicularly aligned to the ground at dead spot.

METHODS

The maximal aerobic capacity (VO2 max) and different parameters of cycling efficiency were measured in 14 (mean±SD of age: 26±5) non-obese (body mass index: 26.0±3.0 kg/m2) healthy men in two different occasions at intervals of 2 days using alternately and in randomized order both the traditional crank system and the system without dead spot respectively.

RESULTS

The workload performed was significantly higher with the new crank system as suggested by the higher exercise duration (12.89 ±2.36 vs. 13.33±2.30 min; P=0.032).

CONCLUSION

The favourable results obtained in this study using the new chainring may be in consequence of a more efficient biomechanics of pedalling that does not reflect changes in O2 consumption and CO2 produced. However, it is not possible to exclude that involuntary motivational factors may have induced the difference in the time test since it was not possible to blind subjects about the two crank systems. Further investigations are necessary to confirm the results of this exploratory study and give a more exhaustive explanation about the mechanisms that allow the possible better performance with this new chainring system.

Glycaemic variability using continuous glucose monitoring and endothelial function in the metabolic syndrome and in Type 2 diabetes

AIMS

Subjects who are at increased risk of developing diabetes may have increased glycaemic variability associated with endothelial dysfunction and possibly subclinical atherosclerosis, which may lead to increased cardiovascular risk observed at the time of diabetes diagnosis. To investigate this hypothesis, we measured endothelial function, carotid intima-media thickness and glycaemic variability using 48-h continuous subcutaneous glucose monitoring in 3 groups of overweight or obese subjects--those without the metabolic syndrome, and those with the metabolic syndrome with or without newly diagnosed Type 2 diabetes.

METHODS

Consecutive subjects, aged 30-65 years with a body mass index >or= 25 kg/m(2) were recruited. Patients were classified as with or without the metabolic syndrome,or as metabolic syndrome with newly diagnosed Type 2 DM. Glycaemic variability was calculated in terms of the coefficient of variation. Endothelial function was measured using brachial artery flow-mediated dilation.

RESULTS

We identified 75 subjects. Mean flow mediated dilation decreased (P < 0.001) and carotid intima-media thickness increased (P < 0.05) across groups. Flow mediated dilation predictors included mean 48-h continuous subcutaneous glucose monitoring values (beta = -0.022; P < 0.005) and the coefficient of variation (beta = -0.10; P = 0.01). Carotid intima-media thickness predictors included age (beta = 0.009; P < 0.001) and flow mediated dilation (beta = -0.014; P = 0.076). Patients re-stratified according to cut-offs for mean 48-h glycaemia and variability demonstrated that subjects with high mean glycaemia but low coefficient of variability had similar flow mediated dilation and carotid intima-media thickness to subjects with low mean glycaemia but high coefficient of variation.

CONCLUSIONS

This study suggests that glycaemic variability influences endothelial function even in non-diabetic subjects. Such variability may explain the increased cardiovascular risk observed in patients prior to developing overt Type 2 diabetes.

A low reported energy intake is associated with metabolic syndrome

BACKGROUND AND AIMS

Metabolic syndrome (MS) may be associated with the presence of an energy-sparing metabolism that predisposes to the excess accumulation of body fat. This study examined the relationship between reported energy intake and obesity in individuals with and without MS.

METHODS AND RESULTS

Ninety consecutive non-diabetic obese subjects were divided into 2 groups based on the presence (MS+: no.=50) or absence (MS-: no.=40) of MS. The study design was cross-sectional. The 3-day food record method was used to assess the subjects' usual energy intake and the Diet Readiness Test (DRT) was also administered. Compared to the MS- group, the MS+ group had a significantly higher body weight, body mass index (mean+/-SEM: 39.1+/-1.3 vs 31.5+/-0.9, p<0.001) and fat mass. The absolute energy intake of the MS+ group (8629+/-331 kJ/24h) did not differ from that of the MS- group (8571+/-515 kJ/24h; p=ns). The daily energy intake normalized for the fat-free mass (FFM) size was higher in the MS- group (163+/-8 kJ/kg-FFM x 24h) than in the MS+ group (138+/-4 kJ/kg-FFM x 24h; p<0.03). The DRT test results were similar in both groups except that section 6 (exercise patterns and attitudes) score was lower in the MS+ group (10.0+/-0.5) than in the MS- group (11.9+/-0.5; p<0.01).

CONCLUSION

The results of this study support the hypothesis that subjects with MS have an energy-sparing metabolism.

Effects of hypocaloric very-low-carbohydrate diet vs. Mediterranean diet on endothelial function in obese women*

Obesity is a cardiovascular risk factor associated with endothelial dysfunction, but the effect of different weight loss strategies on endothelial function is not known. The effect of diet on endothelial function in two hypocaloric diets, a very-low-carbohydrate diet (A) and a Mediterranean diet (M), was measured by brachial artery flow-mediated dilation (FMD). Design Using a longitudinal, randomized, open study design, subjects were engaged in a 2-month weight loss diet. FMD, inflammatory cytokines [interleukin-6 (IL-6) and tumour necrosis factor-alpha] and a marker of oxidative stress [8-iso-prostaglandin F2alpha (8-iso-PGF2alpha)] were measured in subjects on three occasions: before initiating the diet (T0), after 5-7 days of dieting (T5) and after 2 months of dieting (T60). The very short- and medium-term time points were established to discriminate respectively the effect of the diet itself (T5) from that of weight loss (T60). Twenty overweight/obese but otherwise healthy women (BMI: 27-34.9 kg m(-2); age 30-50 years) completed the study. Results Group A lost more weight (mean +/- SEM; -7.6 +/- 0.8 kg) than group M (-4.9 +/- 0.6 kg, P = 0.014) at T60. The FMD was not significantly different between the two groups at T0 (group A: 12.2 +/- 2.9% vs. group B: 10.3 +/- 2.3%, P = ns). In group A, FMD was significantly reduced at T5 and returned to baseline at T60; in group M, FMD increased at T5 and returned to baseline at T60 (P = 0.007 for diet x time interaction). Serum concentrations of IL-6 and 8-iso-PGF2alpha were not significantly different between the two groups at T0 and increased significantly at T5 only in group A (P < 0.001 and P < 0.005 respectively). Conclusion As endothelial dysfunction is known to be associated with acute cardiovascular events, this study suggests that the cardiovascular risk might be increased in the first days of a very-low-carbohydrate diet.

Favorable clinical heart and bone effects of anti-thyroid drug therapy in endogenous subclinical hyperthyroidism

Although subclinical hyperthyroidism (SCH) has been associated with increased risk of osteoporosis and cardiac arrhythmias, its treatment is still controversial. This study was designed as a prospective, randomized, intervention, control-study with a 1-year follow-up in order to investigate whether normalization of serum TSH in SCH using methimazole has favorable bone and heart clinical effects. Fourteen patients with endogenous SCH (not Graves' disease) were enrolled, 7 (5 women/2 men; group T) were treated with methimazole (2.5-7.5 mg/day), and 7 (5 women/2 men; group C) were followed without treatment; 10 healthy subjects were also included in the study as controls. Serum free-T3 (FT3), free-T4 (FT4) and TSH, thyroid echography, bone stiffness index (SI), as measured by heel ultrasonometry, and 24-h electrocardiography monitoring were obtained. SCH patients exhibited higher systolic and diastolic blood pressure than control subjects. They also had a significantly higher number of both ventricular premature beats (VPB) (mean+/-SEM: 681+/-238 vs 6+/-2 beats/24 h; p<0.02) and atrial premature beats (APB) (mean+/-SEM: 495+/-331 vs 7+/-2 beats/24 h; p<0.0001), and a lower SI (66+/-5 vs 96+/-3; p<0.001). Twelve months after normalization of TSH with the use of methimazole, the number of VPB decreased significantly (947+/-443 vs 214+/-109 beats/24 h; p<0.05) while it remained unchanged in untreated SCH patients (414+/-163 vs 487+/-152 beats/24 h; p=ns). An insignificant therapy effect was observed as far as APB were concerned (826+/-660 vs 144+/-75 beats/24 h; p=ns), however their number increased significantly in the untreated group (463+/-49 vs 215+/-46 beats/24 h; p<0.05). The SI increased significantly as a result of therapy in group T (64.1+/-4.8 vs 70.0+/-5.3; p<0.02) and was further reduced in group C at the end of the study (69.1+/-7.3 vs 62.9+/-7.1; p<0.001). No adverse effect was observed in group T. In conclusion, anti-thyroid therapy seems to have favor-able bone and heart clinical effects in subjects with endogenous SCH.

Low relative resting metabolic rate and body weight gain in adult Caucasian Italians

OBJECTIVE

To investigate the relationship between resting metabolic rate (RMR) and subsequent changes in body size and degree of fatness in a group of adult Caucasian Italians.

DESIGN

Prospective, longitudinal, observational study.

SUBJECTS

In total, 155 subjects (72 males and 83 females, age range: 18-55 y; BMI: 17.5-63.4 kg/m2) were evaluated. In total, 43 (26 m and 17 f; BMI: 28.9+/-1.1 kg/m2, mean+/-s.e.m.) of them were reassessed 10-12 y later.

MEASUREMENTS

Anthropometric and body composition (bioimpedance analysis) parameters and RMR (indirect calorimetry) were taken at baseline and after 10-12 y.

RESULTS

Subjects (15 m, 8 f) who gained body weight (arbitrarily defined as a change in body weight > or = 5 kg) had baseline BMI (29.9+/-1.8 vs 28.0+/-1.4; P = NS) and body composition in terms of fat mass (FM%) and fat-free mass (FFM kg) comparable to those of the subjects (11 m, 9 f) whose body weight remained stable. Baseline RMR was significantly lower in subjects who gained weight than in those who did not (108+/-2.1 vs 122+/-3.1 kJ/kg-FFM 24 h; P < 0.001), although it did not differ significantly between the two groups (119+/-2 vs 121+/-2 kJ/kg-FFM 24 h; P = NS) 10-12 y later. Baseline RMR was inversely correlated to both change in body weight (r = -0.57; P < 0.001) and FM (r = -0.50; P < 0.001).

CONCLUSION

A low RMR normalized for FFM appears to be associated with body weight gain in the long run in adult Caucasian Italians.

Bioelectrical characteristics of type 1 and type 2 diabetic subjects with reference to body water compartments

Since bioelectrical characteristics correspond well to body water compartments, this study investigated bioelectrical differences between type 1 and type 2 diabetic subjects that could reflect differences in body water compartments. We investigated cross-sectionally 612 adult subjects, classified into 10 groups according to sex and disease (control, obese normal glucose tolerant, non-obese type 2 diabetes, obese type 2 diabetes, type 1 diabetes). Resistance (R), reactance (Xc) and phase angle (PA) were measured (800 microA - 50 kHz alternating current). The bioelectrical vector was obtained by plotting R and Xc normalized for height (ht), it is easily identified on the basis of the length (inversely related to the total body water, likewise R) and direction, given by the PA (inversely related to the extra-/intra-cellular water - ECW/ICW -). Results show that disease and sex had a significant (ANOVA: P<0.0001 for both F disease and F sex) and independent effect on both R/ht and Xc/ht; no difference was found between type 2 and type 1 diabetic groups. A bioelectrical vector with a lower PA characterized both type 2 and type 1 diabetic groups. An independent positive correlation between fasting plasma glucose and R/ht and a negative correlation between fasting plasma glucose and PA were observed. These findings suggest a non-different body water content and distribution between type 2 and type 1 diabetic subjects; the bioelectrical vector indicates a higher ECW/ICW in type 2 and type 1 diabetic compared to nondiabetic subjects.

Factors associated with autonomic nervous function in type 1 and type 2 diabetic subjects free of clinical manifestations of autonomic neuropathy

Even though autonomic diabetic neuropathy is highly prevalent and a noted risk factor for cardiovascular morbidity and mortality, very little is known about factors associated with it. We carried out standard autonomic nervous system function tests by means of a computerized portable system on 55 diabetic patients (22 with type 1 diabetes, 33 with type 2 diabetes) who had no signs or symptoms of autonomic diabetic neuropathy and on 10 age- and sex-matched healthy control subjects. Test results of patients with type 1 diabetes did not differ significantly from those with type 2 diabetes. Of the clinical, metabolic, and anthropometric variables considered, only the duration of diabetes was inversely and independently correlated to deep breathing test scores (E:I ratio value of deep breathing 1.38-0.009. years of diabetes; R2 = 0.25). The duration of diabetes was inversely correlated to variations in orthostatic systolic blood pressure (r = -0.37, p < 0.01). The prevalence of diabetic retinopathy (score: 1 = no; 2 = yes) was significantly higher in the diabetic group with lower deep breathing values (1.8 +/- 0.3 vs 1.0 +/- 0.0; p < 0.01). The prevalence of ischemic electrocardiographic alterations (score: 1 = no; 2 = yes) was significantly higher in the diabetic group with a poorer orthostatic systolic blood pressure response (1.4 +/- 0.1 vs 1.2 +/- 0.1; p < 0.01). This study suggests that 1) autonomic neuropathy is correlated to disease duration; 2) type of diabetes, present level of metabolic compensation, and anthropometric characteristics do not seem correlated to this complication; 3) diabetic retinopathy and ischemic cardiopathy may be correlated to autonomic neuropathy.

[Food habits and cardiovascular risk factors in 2 population samples of western Sicily]

Two population samples in western Sicily, one rural and one urban, were studied to evaluate the influence of dietary habits on cardiovascular risk factors. One hundred and fifty-five rural subjects (73 males, 82 females) and 155 age- and sex-matched urban subjects (71 males, 84 females) were enrolled. All subjects related their personal and familial history, physical activity levels, and had a complete physical and instrumental examination. Blood was collected after an overnight fast, without stasis. The following parameters were measured: blood glucose, total cholesterol, HDL-cholesterol, triglycerides, apolipoproteins A1 and B100, fibrinogen, factors VII and VIII, tissue plasminogen activator, plasminogen activator inhibitor, and plasminogen. Dietary habits were recorded on two occasions by means of a week diary (7-day food record). The rural sample followed the so-called "Mediterranean diet", while the urban sample followed a diet with significantly higher cholesterol and fat (in particular saturated fatty acids) intake and a significantly lower fiber intake. Both males and females in the rural population had significantly lower total cholesterol and apolipoprotein B100 levels than those in the urban sample, although rural males had significantly higher HDL-cholesterol levels. Both males and females in the rural sample had significantly lower factor VII and plasminogen activator inhibitor levels, although rural males had lower tissue plasminogen activator and fibrinogen levels than their urban counterparts. The positive effects of the "Mediterranean diet" on lipid, coagulation and fibrinolytic parameters which play a key role in the pathogenesis of atherosclerosis indicate that this dietary pattern should be adopted by the entire population.

Influences of obesity and weight loss on thyroid hormones. A 3-3.5-year follow-up study on obese subjects with surgical bilio-pancreatic by-pass

The effects of changing body size, energy intake and substrate oxidation on serum T4, FT4, T3, FT3 and TSH were investigated in ten morbidly obese subjects (4 men/6 women; age: 37 +/- 6 years; BMI: 53.8 +/- 6.5 kg/m2; mean +/- SD) who had undergone a surgical bilio-pancreatic by-pass in order to reduce their body weight. The starting value of serum FT3 was inversely related to the BMI (r = -0.63; p < 0.05). After 1-3 months, all the subjects were losing weight and their intake of carbohydrates was almost negligible; at this time a significant reduction of T3 (-14.6%; p < 0.0001), T4 (-19.5%; p < 0.0001), and FT3 (-10.5%; p < 0.001) was observed. Nine to 16 months after surgery, all the subjects were still losing weight, although there was no carbohydrate restriction; T3, T4, and FT3 were lower than prior to surgery but were beginning to increase. Finally, after 36-42 months the body weight of all the patients had been stable for at least the previous six months (final BMI: 32.9 +/- 4.1) and their body composition, as assessed by bio-impedance, was almost normal; only the concentrations of FT3 proved to be significantly lower than the basal value (-11.2%; p < 0.03). The change in FT3 proved to be independently influenced by the degree of fat malabsorption but not by changes in any of the physical characteristics considered. All values were always in the normal range; FT4 and TSH did not change significantly during the whole period of study. The final concentrations of TSH proved to be independently related to the postabsorptive protein oxidation (g/24h) (TSH = 2.37-0.018* protein oxidation). These results would suggest that nutritional factors have some influence on the blood levels of thyroid hormones, especially of FT3, while the removal of obesity does not seem to have any independent effect in the long-run.

Anti-single-stranded DNA antibody in the sera of patients with type 2 diabetes mellitus. Relation to vascular complications

Anti-single-stranded(ss)DNA antibodies were searched for by enzyme-linked immunosorbent assay (ELISA) in the serum of 202 outpatients with non-insulin-dependent diabetes mellitus and 135 healthy subjects to investigate their prevalence in the serum of patients with type 2 diabetes and their relationship with the presence of vascular complications. Of the 202 patients 128 had vascular complications. Anti-ssDNA antibodies were observed to be significantly more frequent in the serum of patients with vascular complications (33.6%) and in particular in patients with overt nephropathy (50%) than in patients without complications (6.7%) or controls (6.7%). Anti-ssDNA antibodies have been previously described in patients with type 1 diabetes before clinical evidence of vascular disease and their cross-reactivity with a variety of anionic biological molecules or cells, i.e. platelets and endothelial cells, assessed. It seems not unreasonable that these auto-antibodies detected in patients with type 2 diabetes could be of importance in the pathogenesis or progression of angiopathy.

[Correlation between skinfold thickness and ultrasonography in the study of subcutaneous adipose tissue in females]

The aim of this study was to verify if there is a 1:2 correlation between subcutaneous adipose tissue thickness measured by ultrasonography and skinfold caliper and if this correlation varies in function of the degree of obesity, subcutaneous fat thickness, and the area evaluated. Forty women (age 27.9 +/- 11.7 years, body mass index 28.75 +/- 5.40 Kg/m2, waist to hip ratio 0.77 +/- 0.06) underwent ultrasonographic measurement of subcutaneous adipose tissue and skinfold caliper measurement at nine different sites (bicipital, tricipital, subscapular, suprailiac, epigastric umbilical, hypogastric, gluteal, and femoral). Data analysis confirmed a significant correlation between measurements made by ultrasonography and skinfold plicometry at all sites when the patients were not subdivided according to body mass index or skinfold thickness. When they were subdivided on the basis of body mass index, a significant correlation was found for subjects with a body mass index < 30; when the index was > 30, the correlation was observed at only the subscapular and suprailiac sites, and to a lesser degree at the tricipital and femoral sites. Moreover, a highly significant correlation was found only at sites at which ultrasonographic thickness was not > 20 mm (p < 0.001) with an r value decreasing progressively from 0.685 (thickness < 10 mm) to 0.248 (thickness > 40 mm). Given the great variability of this correlation, we suggest that ultrasonography is preferable to plicometry for the measurement of fat.

Validation of a computerised measurement system for guided routine evaluation of cardiovascular autonomic neuropathy

A study for evaluating the use of the Cardionomic system was conducted in six Italian Centres for Diabetes. Cardionomic is a portable computerised system that is used for a guided step-by-step performance of several cardiovascular tests for autonomic neuropathy (heart rate and blood pressure). It has been compared to the traditional method using an electrocardiograph. In this study, which involved 74 diabetic patients, 392 cardiovascular tests were conducted with the electrocardiograph and 392 were done using the portable system. The results were compared to the results obtained with the ECG assuming the latter as the standard ones. All the indices of validity that were investigated (sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, negative likelihood ratio) indicate that the proposed system is reliable. Because it saves a considerable amount of time and is also easy to use, it represents a valid alternative for the routine screening of autonomic neuropathy.

Resting metabolic rate and postabsorptive substrate oxidation in morbidly obese subjects before and after massive weight loss

OBJECTIVE

To investigate the changes of resting metabolic rate (RMR) and postabsorptive oxidation of carbohydrates (CHO), lipids (LIP) and proteins (PT) in morbidly obese subjects after long-term stable massive weight reduction.

DESIGN

Longitudinal, intervention study of a bilio-pancreatic by-pass.

SUBJECTS

Ten (Four men, six women) obese subjects (BMI: 53.7 +/- 2.1 kg/m2, mean +/- s.e.m.) and 12 (three men, nine women) control subjects (BMI: 21.4 +/- 1.0 kg/m2).

MEASUREMENTS

RMR and substrates oxidation (indirect calorimetry), body composition (bioelectrical impedance), plasma concentrations of glucose, FFA, insulin and thyroid hormones before (T0, prior to surgery), during (T1: 1-3 months, and T2: 9-16 months following surgery) and after (T3: 36-42 months following surgery) massive weight loss.

RESULTS

At T3 BMI proved to be stably reduced to 32.9 +/- 1.3 (P < 0.0001). The RMR progressively reduced both in absolute value (T3: -2566 kJ/24 h; P < 0.0001 vs T0) and normalized for fat-free mass (FFM; T0: 123 +/- 3.8, T1: 109 +/- 3.3, T2: 112 +/- 7.1, T3: 105 +/- 4.6 kJ/kg-FFM.24 h; P < 0.05). At T3 the normalized RMR became significantly lower than the corresponding value of a control group (118 +/- 2.5 kJ/kg-FFM.24 h; P < 0.01). The long term trend in substrates oxidation showed that CHO oxidation increased while LIP oxidation decreased; PT oxidation did not significantly change for the whole of the study.

CONCLUSION

Previously morbid obese subjects have an energy sparing metabolism and a normal postabsorptive oxidation of LIP and CHO.

[Assessment of body composition in groups of subjects with different body size. Comparison of skinfold thickness and impedance methods]

The aim of our study was to compare plicometry and bioelectrical impedance analysis as methods for body composition assessment (fat mass-FM%, fat-free mass-FFM) and to extrapolate population-specific equations in order to predict the plicometrically-derived FM and FFM on the basis of body resistance. A cross-sectional study was carried out at the Diabetes Out-Patient Clinic, Department of Internal Medicine, University of Palermo, Italy. We examined 102 subjects (45 men, 57 women, age range 30-45 years) divided into three groups: Group N (36 normal weight subjects, body mass index-BMI = weight/height2 = 24.5 +/- 0.8), Group O (35 obese subjects, BMI = 35.1 +/- 0.4), and Group GO (morbid obese subjects, BMI = 49.2 +/- 1.2) as well as a control group of 30 subjects (12 men, 18 women, age range 30-45 years, BMI = 20.9-63.1). We measured the following parameters: bioelectrical impedance analysis (body resistance: R), plicometry (triceps, biceps, subscapular, and suprailiac skinfolds), height (Ht), weight (W). The two methods were comparable in Groups N and O. In Group GO, however, especially in men and for FM%, measurements were significantly different. Plicometrically-determined FM% and FFM-Kg were significantly correlated to R.W/Ht2 (r = 0.821, p < 0.0001) and to Ht2/R (r = 0.867, p < 0.0001) respectively. The following prediction formulas for plicometric FM and FFM from body resistance and anthropometric variables were obtained: 1) FM% = 22.3 (R.W/Ht2)-2.2, and 2) FFM-Kg = 1.1 (Ht2/R)-3.1.(ABSTRACT TRUNCATED AT 250 WORDS)

Resting energy expenditure and body composition in morbidly obese, obese and control subjects

Resting energy expenditure (REE) was investigated by indirect calorimetry in relation to body composition and to different degrees of obesity in order to assess if a defective energy expenditure contributes to extra body fat accumulation. Differences were found between control subjects (group C; BMI 23 +/- 0.5 kg/m2, REE 5890 +/- 218 kJ/day; mean +/- SEM) and obese subjects (group O; BMI 34.2 +/- 0.9 kg/m2, REE 7447 +/- 360 kJ/day; P < 0.0001) and between group C and morbidly obese subjects (group MO; BMI 49.9 +/- 1.6 kg/m2, REE 8330 +/- 360 kJ/day; P < 0.0001); REE was not significantly different between groups O and MO. Body composition data were obtained by means of body impedance analysis. Even though group MO had a fat mass higher than group O, body cell mass, the metabolically active body compartment, was similar in groups O and MO, and this fact may have contributed to the similar REE in the two groups. Multiple regression analysis gave the following equation as the best predictor of REE: REE (kJ/day) = 1591 +/- 49BW + 74BCM - 737G (R2 = 0.88), where BW is body weight, BCM is body cell mass and G is a dummy variable coding group membership (group C = 1; group O = 2; group MO = 3). Thus the analysis showed a negative impact of obesity on REE beyond body composition variables.

Plasma endothelin levels in NIDDM patients with macroangiopathy

To determine whether plasma endothelin, a potent vasoconstrictive peptide, is elevated in NIDDM patients, we compared a group of 15 NIDDM patients with macroangiopathy of mean age 60.60 +/- 2.33 years with 15 NIDDM randomly selected matched patients without macroangiopathy. Plasma endothelin levels were significantly increased in NIDDM patients with macroangiopathy (4.22 +/- 0.57 pmol/L) and in NIDDM patients without macroangiopathy (3.81 +/- 0.51 pmol/L). Although endothelin values did not differ between NIDDM groups, both represented significant difference from control values (2.46 +/- 0.24 pmol/L). No significant correlations were found between plasma endothelin and age (rs = 0.11), duration of diabetes mellitus (rs = 0.06), BMI (rs = 0.19), plasma glucose (rs = 0.15), plasma fructosamine (rs = 0.02). These findings confirm that in diabetes mellitus a primary disturbance in endothelin production from vascular endothelium exists as an early phenomenon rather than a result of advanced stage of the disease.

Serum lipoprotein Lp(a) in obesity

Lipoprotein(a) [Lp(a)] has been added to the list of independent risk factors for cardiovascular disease (CVD), whose incidence is greater in obese subjects. There are few data available on the serum Lp(a) concentrations in obese individuals with or without insulin dependent diabetes mellitus (NIDDM). We selected 31 obese men with normal glucose tolerance (NGT) tests, 15 obese diabetic men, 14 non obese diabetic men and 17 healthy men as controls. We measured serum total cholesterol, HDL cholesterol, triglycerides, glucose, insulin and Lp(a). The mean Lp(a) levels in NGT obese men were 70.00 +/- 13.40 mg/l, which were similar to those found in normal controls (75.98 +/- 24.70 mg/l); significantly higher mean Lp(a) levels were found in obese diabetic men (168.84 +/- 56.43 mg/l) and in non obese diabetic men (240.85 +/- 63.35 mg/l). No significant correlation between Lp(a) levels and age, body mass index (BMI), total cholesterol, HDL cholesterol, triglycerides, insulin, was found; only a significant positive correlation between Lp(a) levels and glucose could be revealed (P < 0.05). Since higher levels of Lp(a) were found in NIDDM subjects with or without obesity, we conclude that hyperglycemia may influence the levels of serum Lp(a) facilitating its glycosylation in the liver with the consequence of a decline in its catabolic rate.

[Plasma levels of beta-endorphin in obese subjects with normal glucose tolerance test and in diabetics]

Forty obese subjects with normal glucose tolerance test (NGTT) thirteen diabetic obese subjects and sixteen normal subjects were studied to evaluate the possible interactions between beta-endorphin (B-Ep) and glucose homeostasis. On the basis of baseline B-Ep levels, two subgroups were selected: one group with normal mean values of B-Ep (7.02 +/- 0.59 pmol/l); another group with elevated mean values of B-Ep (18.95 +/- 1.52 pmol/l). No differences between these subgroups were found as regards body mass index (BMI), insulin and glucagon levels. Normal B-Ep values were found in diabetic obese subjects. No significant correlation was found between B-Ep and BMI, insulin or glucagon. Considering that B-Ep is involved in eating behavior and on the basis of our results, we suggest that elevated B-Ep levels can be found only in those obese NGTT subjects whose obesity is probably related to an abnormal modulation of food intake, such as hyperphagia.

Glucose-induced thermogenesis in obese subjects with or without familial history of obesity

In order to assess to what extent familial factors play a role in thermogenesis of obese individuals, the 3 h response to a 100 g glucose oral load was measured in 11 obese subjects (6 m, 5 f) with a familial history of obesity and/or obesity-non-insulin dependent diabetes mellitus (NIDDM, group A); these were compared to 9 obese subjects (5 m, 4 f) without familial history of these disorders (group B). All subjects had normal glucose tolerance and the two groups were comparable with respect to anthropometric features. The glucose-induced thermogenesis of group A (7.9 +/- 1.2 per cent) above preload energy expenditure was significantly lower (P less than 0.01) than that observed in group B (13.5 +/- 0.5 per cent). The same conclusions were obtained when the results were expressed as a percentage of the glucose load ingested (4.4 +/- 0.67 and 7.8 +/- 0.80 in group A and group B respectively, P less than 0.01). Despite these differences the pattern of change in glycaemia, insulinaemia, C-peptidaemia and glucagonaemia in response to the glucose load was the same between the two groups. Total glucose oxidation as well as non-oxidative glucose disposal did not differ between the two groups. These results seem to support the hypothesis that genetic factors may contribute to the low thermogenic response observed in some individuals with a familial history of obesity and/or obesity-NIDDM.

[Energy expenditure at rest and body composition in obese subjects before and after weight loss]

In 7 obese subjects (3 males and 4 females), before (T0) and after (T60) weight loss, and in 10 nonobese subjects (4 males and 6 females) as controls, resting energy expenditure (REE) and body composition were evaluated. In obese subjects fat-free mass (FFM) and fat mass (FM) were significantly reduced after weight loss. REE, expressed in absolute value, was significantly higher in obese subjects at T0 with respect to controls (1683 +/- 77.3 vs. 1425 +/- 70.5 Kcal/day; p less than 0.05); in obese group REE was significantly lower at T60 (1563 +/- 63.5 Kcal/day) than at T0 (p less than 0.01). The decrease in REE observed in the obese group after weight loss was related only to the loss of FFM (r = 0.88; p less than 0.01). REE, expressed in relation to FFM, was not different between control and obese subjects at T0 (28.64 +/- 0.42 vs 26.40 +/- 1.08 Kcal/Kg-FFM/day; pns); however, this value was significantly lower in the obese group at T60 (25.99 +/- 1.07 Kcal/Kg-FFM/day) with respect to controls (p less than 0.05). It is concluded that a reduction in REE, due at least in part to the loss of FFM, may contribute to the difficulty in the maintenance of body weight often observed in obese subjects after a period on hypocaloric diet.

[Basal lipid energy utilization in obese women and men]

In 16 abdominal type obese males, in 16 gluteal-femoral type obese females and in 10 nonobese males and 9 nonobese females, as controls, the influence of body fat distribution on basal lipid oxidation was evaluated by indirect calorimetry. Basal lipid oxidation was significantly higher in the obese males (1.21 +/- 0.12 g/kg-FFM.die) than in the nonobese males (0.47 +/- 0.13 g/kg-FFM.die; p less than 0.001), but not significantly different between obese and nonobese females (0.98 +/- 0.16 and 0.89 +/- 0.13 g/kg-FFM.die; p ns). A significant correlation between basal lipid oxidation and percentage of body fat was found only in the male subjects (r = 0.51; p less than 0.01). These results suggest that basal lipid oxidation differs in the two sexes according to adipose tissue anatomic location.

The effects of muscular exercise on glucose, free fatty acids, alanine and lactate in type I diabetic subjects in relation to metabolic control

Metabolic effects of muscular exercise were studied in eleven subjects with type I diabetes mellitus during poor metabolic control, and again during good metabolic control, and in ten healthy control subjects. All the subjects were submitted to a submaximal gradual triangular test on an electrically braked bicycle ergometer; glucose, FFA, alanine and lactate were measured at rest, and after exercise. In poorly controlled patients, glucose and FFA were unchanged after exercise, whereas blood alanine and lactate increased by a percentage similar to that of the controls, and well-controlled diabetic patients. Baseline alanine concentrations were lower and lactate concentrations higher than in the controls and well-controlled patients. After adequate metabolic control was achieved, in the well-controlled diabetic patients a normalization of pre-exercise alanine and lactate levels and a decrease in blood glucose and FFA after exercise was observed.

Effects of muscular exercise on erythrocyte adenosine triphosphate concentration in patients with insulin-dependent diabetes mellitus

Type I diabetes mellitus represents a metabolic disorder in which intracellular glycolytic pathway is inhibited by insulin deficiency, with the subsequent decreased availability of energetic substrates such as ATP. Some aspects of the energetic metabolism in response to an intensive demand (muscular exercise) were investigated, in a group of 10 ketotic diabetic patients, by measuring erythrocyte adenosine triphosphate (ATP) and blood glucose, free fatty acids (FFA) and lactate levels. In the diabetic subjects, in comparison with normal subjects, the decreased levels of erythrocyte ATP at rest did not increase after exercise, while the increased levels of FFA at rest did not diminish after exercise. The results show that the impaired erythrocyte glycolysis may produce reduced levels of ATP not only at rest, but also after exercise, when muscular contraction results in a manifold increase in cellular energy requirements. In addition, other metabolic systems providing energy for the exercising muscle, such as FFA utilization, are impaired in the ketotic diabetic patients.

Effects of dynamic exercise and metabolic control on left ventricular performance in insulin-dependent diabetes mellitus

In subclinical diabetic cardiomyopathy, previous reports did not positively correlate the altered cardiac performance with metabolic parameters. Fifteen insulin-dependent diabetic subjects, without any clinical or instrumental evidence of heart diseases, were studied. Signs of diabetic microangiopathy were absent. Systolic time intervals, metabolic and hormonal parameters (blood glucose, free fatty acids, blood lactate and plasma norepinephrine) were evaluated at rest and after dynamic exercise during poor (MAGE 6.36 +/- 0.72 mmol/l) and good (MAGE 3.46 +/- 0.66 mmol/l) metabolic control, obtained by means of insulin therapy. Rest values of systolic time intervals were normal during poor and good metabolic control. After exercise, pre-ejection period/left ventricular ejection time ratio increased mainly during poor control as a result of an increased pre-ejection period: conversely, a smaller increase in pre-ejection period/left ventricular ejection time ratio occurred during good metabolic control. The exercise induced free fatty acids utilization did not occur during poor control as it occurred during good control. The percentage of increments in blood lactate was virtually identical in ketotic and non-ketotic patients and in normal subjects. High norepinephrine plasma levels were observed both at rest and during dynamic exercise in poorly controlled diabetic patients. Conclusively, testing of systolic time intervals after exercise might be useful in the detection of preclinical diabetic cardiomyopathy. The decreased cardiac functional reserve observed during poor control might be related to an altered energetic fuel utilization.

[Effects of acute ingestion of ethanol on several metabolic parameters (blood sugar, triglycerides, non-esterified fatty acids, lactic acid and uric acid) in subjects with type I diabetes mellitus]

7 diabetic type I patients and 17 normal subjects underwent to acute ethanol oral load (0,8 g/Kg), in order to investigate the modifications produced on glucose, triglycerides, FFA, lactate and uric acid plasma values. Our results show basal differences between diabetics and controls in all these parameters; furthermore, acute ethanol ingestion produces no significant variations of blood glucose in both groups, a significant decrease in FFA levels, an increase of triglyceridemic levels, more evident in diabetics and an increase of lactate, earlier in normals. On the other hand, there is no significant modification in uric acid plasma levels in controls, whereas in diabetics there is an increase, probably due to more elevated lactacidemic values in the late phase of the test.

[Interrelation between gastrin and insulin in a group of normal subjects]

The insulin secretory action of gastrin during O.G.T.T. has been assessed. The insulinaemic and gastrinaemic curves were evaluated in a group of normal subjects submitted to oral glucose load, using radioimmunological measurement techniques. At a later stage, the insulinaemic values were considered in the same subjects after administration of a gastrin analogue (pentagastrin) by the subcutaneous route in a dose such as to provoke a maximal gastric acid response. The data suggest that any participation of gastrin in the regulation of insulin secretion following a glucose meal can be excluded.

[Effects of prolonged fasting and vagotomy on the ultrastructure of contractile myocardium in pigeons]

Ultrastructural changes in pigeon heart following long fasting and vagotomy are reported. In the fasting pigeons several fat droplets surrounding the adjacent nearest mitochondria represent the most important finding. Conversely, in the fasting and vagotomized pigeons the mean finding is a large decrease of fat droplets. Ultrastructural findings appear related with biochemical changes by different experimental conditions.