A novel MRPS34 gene mutation with combined OXPHOS deficiency in an adult patient with Leigh syndrome.

We report a novel pathogenic variant (c.223G > C; p.Gly75Arg) in the gene encoding the small mitoribosomal subunit protein mS34 in a long-surviving patient with Leigh Syndrome who was genetically diagnosed at age 34 years. The patient presented with delayed motor milestones and a stepwise motor deterioration during life, along with brain MRI alterations involving the subcortical white matter, deep grey nuclei and in particular the internal globi pallidi, that appeared calcified on CT scan. The novel variant is associated with a reduction of mS34 protein levels and of the OXPHOS complex I and IV subunits in peripheral blood mononuclear cells of the case. This study expands the number of variants that, by affecting the stability of the mitoribosome, may cause an OXPHOS deficiency in Leigh Syndrome and reports, for the first time, an unusual long survival in a patient with a homozygous MRPS34 pathogenic variant.

Vitamin D status and non-alcoholic fatty liver disease in patients with type 1 diabetes.

PURPOSE: In patients with type 1 diabetes (T1D), the prevalence of non-alcoholic fatty liver disease (NAFLD) ranges from 10 to 53% and contrasting evidence suggests that vitamin D deficiency may favor liver fat accumulation. Here, we investigated the association between vitamin D status and NAFLD in adults with T1D. METHODS: 220 consecutive adult T1D patients on multiple daily injections or continuous subcutaneous insulin infusion and not taking calcium or vitamin D supplements were included. Patient characteristics, 25(OH)D serum levels, and metabolic parameters were analyzed. Vitamin D status was defined as sufficiency ( ≥ 75 nmol/L; 30 ng/ml), insufficiency (50-75 nmol/L; 20-30 ng/ml), or deficiency ( < 50 nmol/L; 20 ng/ml). NAFLD was diagnosed at ultrasound examination and graded 0-3. RESULTS: NAFLD was present in 57 patients (29.5%): 51 grade 1, 5 grade 2, and 1 grade 3. Median 25(OH)D levels were 53 nmol/L (IQR 38-70) in patients with NAFLD and 50 nmol/L (34-69) in patients without (p = 0.46). At multivariable analysis, NAFLD was not associated with 25(OH)D levels (p = 0.42) or vitamin D deficiency (p = 0.55), while BMI (OR 1.16, 95% CI 1.07-1.27) and serum triglycerides (OR 1.02, 95% CI 1.01-1.03) were independently associated with NAFLD. CONCLUSIONS: Vitamin D status appears to have no link with low-grade NAFLD in patients with type 1 diabetes.

In Type 1 diabetic patients with good glycaemic control, blood glucose variability is lower during continuous subcutaneous insulin infusion than during multiple daily injections with insulin glargine.

AIMS: The superiority of continuous subcutaneous insulin infusion (CSII) over multiple daily injections (MDI) with glargine is uncertain. In this randomized cross-over study, we compared CSII and MDI with glargine in patients with Type 1 diabetes well controlled with CSII. The primary end-point was glucose variability. METHODS: Thirty-nine patients [38.1 +/- 9.3 years old (mean +/- sd), diabetes duration 16.6 +/- 8.2 years, glycated haemoglobin (HbA(1c)) 7.6 +/- 0.8%], already on CSII for at least 6 months, were randomly assigned to CSII with lispro or MDI with lispro and glargine. After 4 months they were switched to the alternative treatment. During the last month of each treatment blood glucose variability was analysed using glucose standard deviation, mean amplitude of glycaemic excursions (MAGE), lability index and average daily risk range (ADRR). As secondary end-points we analysed blood glucose profile, HbA(1c), number of episodes of hypo- and hyperglycaemia, lipid profile, free fatty acids (FFA), growth hormone and treatment satisfaction. RESULTS: During CSII, glucose variability was 5-12% lower than during MDI with glargine. The difference was significant only before breakfast considering glucose standard deviation (P = 0.011), significant overall using MAGE (P = 0.016) and lability index (P = 0.005) and not significant using ADRR. Although HbA(1c) was similar during both treatments, during CSII blood glucose levels were significantly lower, hyperglycaemic episodes were fewer, daily insulin dose was less, FFA were lower and treatment satisfaction was greater than during MDI with glargine. The frequency of hypoglycaemic episodes was similar during both treatments. CONCLUSIONS: During CSII, glucose variability is lower, glycaemic control better and treatment satisfaction higher than during MDI with glargine.

Rapid, simple and effective technical procedure for the regeneration of IgG and HSA affinity columns for proteomic analysis.

In plasma and serum, the presence of high-abundance proteins can overwhelm the signals of low-abundance proteins, which then become undetectable either by two-dimensional gels or chromatographic techniques. Therefore, depletion of abundant proteins is a prerequisite to detect low-abundance components. Furthermore, the regeneration of pre-purification tools could be money-saving. We applied an affinity chromatography kit to remove albumin and the immunoglobulin chains from plasma and propose a simple and effective technical procedure for the regeneration of these affinity columns.

In situ protein Kinase C activity is increased in cultured fibroblasts from Type 1 diabetic patients with nephropathy.

AIMS/HYPOTHESIS: To verify whether individual susceptibility to diabetic nephropathy resides in an intrinsic difference in Protein Kinase C (PKC) activity. METHODS: We compared the effect of different glucose concentrations on PKC activity, PKC isoform expression and diacylglycerol (DAG) content in cultured fibroblasts from 14 Type 1 diabetic patients who developed nephropathy with those in cells from 14 patients without nephropathy. We recruited 14 normal subjects as control patients. Forearm skin fibroblasts were cultured in either normal (5 mmol/l) or high (20 mmol/l) glucose concentrations. RESULTS: In normal glucose, in situ PKC activity was higher in Type 1 patients with nephropathy (10.1+/-1.4 pmol/min/mg protein; p<0.01) than in those without (6.8+/-0.8) and the normal control subjects (6.3+/-0.5). This difference was due to increased concentrations of PKCalpha isoform in the membrane fraction of fibroblasts from patients with nephropathy. DAG content was also higher in cells from Type 1 patients with nephropathy. Incubation in high glucose concentration caused a further increase in PKC activity and DAG content in quiescent fibroblasts from patients with diabetic nephropathy, with no significant changes in cells from diabetic patients without nephropathy and normal control subjects. CONCLUSION/INTERPRETATION: Differences in PKC activation could contribute to the individual susceptibility to renal damage in Type 1 diabetic patients.

Diabetic ketosis activates lymphomonocyte-inducible nitric oxide synthase.

AIMS: Inappropriate production of nitric oxide (NO) may be responsible for the haemodynamic disturbances of diabetic ketoacidosis. We investigated whether this metabolic condition is associated with increased plasma nitrate (the stable oxidation product of NO) levels and NO synthase gene expression in lymphomonocytes. RESEARCH DESIGN AND METHODS: Plasma nitrate concentrations, lymphomonocyte-inducible nitric oxide synthase (iNOS) gene expression, tumour necrosis factor-alpha (TNF-alpha) and soluble thrombomodulin were measured in 11 Type 1 diabetic patients at baseline, during mild ketosis and after euglycaemia was re-established. RESULTS: During diabetic ketosis plasma nitrate concentrations were higher (18 (16-21) vs. 9 (7-11) micro mol/l; (95% lower-upper confidence interval) P < 0.05) than at baseline. At baseline lymphomonocyte iNOS mRNA expression and iNOS protein levels were undetectable, but in ketosis both were increased (both at P < 0.0001). After recovery from ketosis, NO3 concentration, iNOS mRNA, and iNOS expression (270 +/- 36%, mean +/- sd) decreased but not significantly. No significant changes were observed in either TNF-alpha or soluble thrombomodulin levels between the three conditions. CONCLUSIONS: Diabetic ketosis is associated with increased nitrate levels and the activation of iNOS expression in circulating lymphomonocytes, but it does not affect either the proinflammatory cytokine TNF-alpha or a marker of endothelial dysfunction such as thrombomodulin. Our data support the hypothesis that, during diabetic ketosis, alterations in NO homeostasis are present in circulating lymphomonocytes.

Insulin infusion normalizes fasting and post-prandial albumin and fibrinogen synthesis in Type 1 diabetes mellitus.

AIMS: The effect of metabolic control on hepatic synthesis of plasma proteins in Type 1 diabetes mellitus (T1DM), in the post-absorptive and post-prandial state, is not known. METHODS: We measured fractional synthetic rates (FSR) of albumin and fibrinogen in six insulin-infused T1DM patients and in five to nine control subjects, before and for approx. 4 h after a mixed liquid meal. Phenylalanine tracer precursor/product relationships and steady-state conditions were used. In the post-absorptive state, patients were studied in near euglycaemic conditions after an overnight intravenous insulin infusion. During the meal (approx. 11 kcal/kg), the insulin infusion rate was increased to maintain plasma glucose concentrations below approx. 10 mmol/l. RESULTS: Post-absorptive FSR of albumin (5.7 +/- 0.6%/day) and fibrinogen (11.3 +/- 0.6%/day) in T1DM were similar to control values (6.4 +/- 0.9 and 13.1 +/- 1.1, respectively). After the meal, albumin FSR increased (P = 0.0032 by anova) in both groups (T1DM, to 14.4 +/- 2.7%/day; controls, to 18.2 +/- 3.7%/day). Fibrinogen FSR also increased (P = 0.0048 by anova) in both the T1DM (to 18.2 +/- 2.6) and the control subjects (to 27.3 +/- 6.2). There was no difference between T1DM and control subjects in the post-prandial FSR of both proteins. CONCLUSIONS: Albumin and fibrinogen FSR in T1DM can be maintained within near-normal ranges by insulin infusion under post-absorptive and post-prandial conditions.

Effect of insulin and angiotensin II on cell calcium in human skin fibroblasts.

We have recently shown that insulin attenuates angiotensin II-induced intracellular Ca(2+) mobilization in human skin fibroblasts from normotensive subjects. This study was designed to investigate the effects of angiotensin II and the interactions between insulin and angiotensin II on intracellular Ca(2+) mobilization in skin fibroblasts from patients with essential hypertension. Fibroblasts were obtained from 9 normotensives and 18 hypertensives. Spectrofluorophotometric free Ca(2+) measurement was performed in monolayers of 24-hour serum-deprived cells. Resting intracellular Ca(2+) level and angiotensin II-stimulated intracellular Ca(2+) peak were higher in fibroblasts from hypertensives compared with those from normotensives. The effect of acute insulin exposure was evaluated in fibroblasts from hypertensives subdivided on the basis of insulin sensitivity. In insulin-sensitive hypertensives, insulin significantly blunted the effects of angiotensin II on intracellular Ca(2+) response, whereas in insulin-resistant patients, insulin did not modify intracellular Ca(2+) response to angiotensin II. Pertussis toxin, a G(ialpha)-inhibitor, reduced angiotensin II-stimulated Ca(2+) peak in insulin-sensitive but not in insulin-resistant hypertensives. In conclusion, the effects of angiotensin II on intracellular Ca(2+) mobilization are more pronounced in fibroblasts from hypertensives compared with those from normotensives, and the inhibitory effect of insulin is blunted in insulin-resistant hypertensives by a G(ialpha) pertussis toxin-sensitive abnormality.

Combination of continuous subcutaneous infusion of insulin and octreotide in Type 1 diabetic patients.

The effect of 7 day continuous subcutaneous infusion of octreotide (200 microg day(-1)) was evaluated in seven insulin-pump treated Type 1 diabetic patients (age 43+/-1.5 year; BMI 25.1+/-0.7 kg m(-2); HbA(1c) 7.4+/-0.3%). A 24-h metabolic and hormonal profile, and a euglycaemic hyperinsulinaemic clamp (0.25, 0.5, 1.0 mg kg(-1) min(-1)), with [3H]glucose infusion and indirect calorimetry, were performed before and after a 7-day octreotide infusion. Mean 24-h plasma glucose was similar before and after octreotide (9.7+/-0.8 vs. 9.1+/-1.0 mmol l(-1)) but insulin requirement dropped by 45% (49+/-4 vs. 27+/-2 U day(-1); P<0.01). Both 24-h plasma hGH and glucagon were suppressed by octreotide (1.85+/-0.35 vs. 0.52+/-0.04 microg l(-1), and 117+/-23 vs. 102+/-14 ng l(-1), respectively). Glucose utilisation increased after octreotide (insulin 0.5 mU kg(-1) min(-1) clamp 3.09+/-0.23 vs. 4.19+/-0.19 mg kg(-1) min(-1); 1 mU kg(-1) min(-1) clamp 5.64+/-0.61 vs. 7.93+/-0.57 mg kg(-1) min(-1); both P<0.05) and endogenous glucose production was similarly suppressed. Glucose oxidation was not affected by octreotide, while the improvement in glucose storage (insulin 1.0 mU kg(-1) min(-1) clamp 3.89+/-0.60 vs. 5.64+/-0.67 mg kg(-1) min(-1), P<0.05) entirely accounted for the increase in glucose disposal. Endogenous glucose production was more effectively suppressed at the two lower insulin infusion rates (P>0.05). Energy expenditure declined after octreotide. Continuous subcutaneous octreotide infusion suppresses counterregulatory hormones, increases insulin-mediated glucose metabolism by enhancing glucose storage, and reduces energy expenditure. These results support a role for counterregulatory hormones in the genesis of insulin resistance and the catabolic state of Type 1 diabetes.

Effect of different times of administration of a single ethanol dose on insulin action, insulin secretion and redox state.

AIMS: Ethanol (EtOH) can affect glucose metabolism by altering the redox state, insulin-mediated glucose uptake and insulin secretion. We sought to determine the effects of an acute oral EtOH load on insulin secretion and glucose tolerance and the importance of a different timing of administration relative to a glucose load. METHODS: Eleven subjects underwent a frequently sampled intravenous glucose tolerance test (FSIGT) on three occasions in random order. In one, EtOH was given 50 min 'before' the FSIGT; on the second, the same amount was administered 6 min after the glucose pulse ('during' study); on the third no EtOH was given. RESULTS: Blood EtOH peaked at 4.43+/-0.24 mmol/l (mean +/- SD) in the 'during' and 4.16+/-0.31 mmol/l in the 'before' study. No differences were noticed in S(I), the index of insulin sensitivity, or in S(G), the glucose effectiveness, between the 'before', 'during' and control studies. There were no differences in the first-phase insulin secretion between the three studies but a significant increase in the sensitivity to glucose of second-phase dynamic insulin response, phi2, in the 'before' (0.062+/-0.036 pmol x min(-2) x (mg(-1) x dl(-1))(-1)) and 'during' (0.063+/-0.059) studies, compared to the control study (0.017+/-0.010, P<0.05) was observed. No differences were observed in the hepatic extraction of insulin. In the 'before' study, there was a significant decline in NEFA (non-esterified fatty acid) concentration from the baseline (mean 602+/-51 micromol/l) to the O min value (mean 353+/-37, P<0.01). During the FSIGT, the mean plasma NEFA concentration was significantly lower in the 'before' and in the 'during' than in the control study. CONCLUSION: An acute oral EtOH load does not impair glucose metabolism, at least in part because of an increased second-phase insulin secretion. Since this effect is observed irrespective of whether EtOH is consumed either before or during the glucose load, the existence of a priming effect is questioned.

Modulatory effect of insulin on release of calcium from human fibroblasts by angiotensin II.

BACKGROUND: Angiotensin II stimulates synthesis and deposition of collagen and might contribute to the vascular and cardiac dysfunction associated with arterial hypertension. Insulin attenuates angiotensin II-induced responses of intracellular Ca2+ concentration ([Ca2+]) in many cell types but this effect is less in insulin-resistant states. The mechanisms of the interaction between insulin and angiotensin II are still not known. OBJECTIVE: To characterize the effects of angiotensin II on intracellular [Ca2+] and the effects of insulin on the angiotensin II-induced response of intracellular [Ca2+] in human skin fibroblasts. METHODS: Spectrofluorophotometric measurements of intracellular [Ca2+] in monolayers of cultured human skin fibroblasts from 15 normotensive patients were performed using Fura-2 at 510 nm emission with excitation wavelengths of 340 and 380 nm. RESULTS: Basal intracellular [Ca2+] in quiescent (24 h serum-deprived) human fibroblasts was 75 +/- 3 nmol/l (n = 20). Administration of angiotensin II elevated intracellular [Ca2+] dose-dependently with a concentration for half-maximal effect of 20 nmol/l. Administration of 100 nmol/l angiotensin II stimulated a rapid and transient increase in intracellular [Ca2+] (from 75 +/- 3 to 130 +/- 2 nmol/l, n = 20). Removal of extracellular calcium did not change peak intracellular [Ca2+], but it did reduce the time to recovery of [Ca2+] (from 64 +/- 4 to 48 +/- 2 s, n = 10, P < 0.01), suggesting that an angiotensin II-induced transmembrane calcium influx had occurred. This hypothesis was confirmed by quenching studies with manganese. The angiotensin II-induced changes in intracellular [Ca2+] were completely blocked by administration of 100 nmol/l of the angiotensin II type 1 receptor inhibitor losartan but not by administration of 100 nmol/l of the angiotensin II type 2 receptor blocker CGP42112A. Acute (20 min) exposure to 100 nmol/l insulin did not alter basal intracellular [Ca2+] in quiescent fibroblasts, but significantly blunted angiotensin II-stimulated peak of [Ca2+] (to 101 +/- 3 nmol/l, P < 0.01, n = 18) and delayed recovery of [Ca2+] (to 99 +/- 5 s, P < 0.01). The inhibitory effect of insulin was observed both with and without extracellular Ca2+. CONCLUSIONS: Our results demonstrate that administration of angiotensin II increases intracellular [Ca2+] in human skin fibroblasts by release of Ca2+ from intracellular Ca2+ stores and by influx of Ca2+ and that administration of insulin attenuates the response of [Ca2+] to angiotensin II but prolongs the time to recovery of [Ca2+].

Evidence for acute stimulation of fibrinogen production by glucagon in humans.

Fibrinogen, an acute-phase protein, and glucagon, a stress hormone, are often elevated in many conditions of physical and metabolic stress, including uncontrolled diabetes. However, the possible mechanisms for this association are poorly known. We have studied the acute effects of selective hyperglucagonemia (raised from -200 to -350 pg/ml for 3 h) on fibrinogen fractional secretion rate (FSR) in eight normal subjects during infusion of somatostatin and replacement doses of insulin, glucagon, and growth hormone. Fibrinogen FSR was evaluated by precursor-product relationships using either Phe (n = 8) or Leu (n = 2) tracers. Hyperglucagonemia did not change either plasma Phe or Tyr specific activity. After hyperglucagonemia, fibrinogen FSR increased by approximately 65% (from 12.9 +/- 3.6 to 21.5 +/- 6.1% per day, P < 0.025) using plasma Phe specific activity as the precursor pool. FSR increased by approximately 80% (from 16.6 +/- 4.8 to 29.4 +/- 8.8% per day, P < 0.025) if plasma Phe specific activity was corrected for the ketoisocaproate/Leu enrichment (or specific activity) ratio to obtain an approximate estimate of intrahepatic Phe specific activity. FSR increased by approximately 60% when using plasma Tyr specific activity as precursor pool (n = 8) (P < 0.05), as well as when using the Leu tracer precursor-product relationship (n = 2). In conclusion, selective hyperglucagonemia for approximately 3 h acutely stimulated fibrinogen FSR using a Phe tracer method. Thus, glucagon may be involved in the increase of fibrinogen concentration and FSR observed under stressed or pathologic conditions.

Dipyridamole-induced ischemia as a prognostic marker of future adverse cardiac events in adult patients with hypertrophic cardiomyopathy. Echo Persantine Italian Cooperative (EPIC) Study Group, Subproject Hypertrophic Cardiomyopathy.

BACKGROUND: Myocardial ischemia may play a role in the natural history of hypertrophic cardiomyopathy (HCM). To assess the relative prevalence and the prognostic value of dipyridamole-induced ischemia, 79 patients with HCM and without concomitant coronary artery disease (53 men; mean age, 46+/-15 years) underwent a high-dose (up to 0.84 mg/kg over 10 minutes) dipyridamole test with 12-lead ECG and two-dimensional echo monitoring and were followed up for a mean of 6 years. METHODS AND RESULTS: Twenty-nine patients (37%) showed ECG (ie, ST depression > or = 2 mV) signs of myocardial ischemia during dipyridamole test (group 1), whereas 50 (63%) had a negative test (group 2). No patient had transient wall motion abnormalities during the dipyridamole test. During the follow-up, 16 events (ie, left ventricular or atrial enlargement, unstable angina, syncope, atrial fibrillation, and bundle-branch block) occurred in 29 patients in group 1 and 5 in 50 patients in group 2 (55% versus 10%, P<.001). Patients with a positive dipyridamole test showed worse 72-month event-free survival rates compared with patients with a negative test (36.2% versus 84.2%, P<.001). A forward stepwise event-free survival analysis identified dipyridamole test positivity by ECG criteria (chi2=19.7, P=.0001), rest gradient (chi2=11.3, P=.0008), and age (chi2=4.1; P=.0413) as independent and additive predictors of subsequent events. CONCLUSIONS: ECG signs of myocardial ischemia elicited by dipyridamole are frequent in patients with HCM and identify patients at higher risk of cardiac events, suggesting a potentially important pathogenetic role of inducible myocardial ischemia in determining adverse cardiac events in these patients.

Hyperglucagonemia stimulates phenylalanine oxidation in humans.

Glucagon stimulates in vitro liver phenylalanine (Phe) degradation, thus inducing net protein catabolism. Whether these effects occur also in vivo in humans is not known. Therefore, we studied the effects of physiological hyperglucagonemia on Phe rate of appearance (Ra), hydroxylation, and oxidation in seven normal volunteers during infusions of somatostatin with replacement doses of insulin and growth hormone. Steady-state Phe kinetics were evaluated using the L-[1-14C]Phe tracer both at the end of a 3-h basal glucagon replacement period (glucagon concentration: 212 +/- 115 ng/l) and after a 3-h hormone infusion at the rate of approximately 3 ng x kg-1 x min-1 (--> 654 +/- 280 ng/l). Hyperglucagonemia did not change plasma Phe concentration and Ra but increased Phe oxidation by approximately 30% (P < 0.01). Oxidation was also increased by approximately 24% (P < 0.01) using plasma [14C]tyrosine (Tyr) specific activity as a precursor pool. Phe hydroxylation to Tyr estimated by assuming a fixed ratio of Tyr to Phe Ra (0.73) did not change. Nonhydroxylated Phe disposal decreased by approximately 6% (P = 0.08). These data show that in humans in the postabsorptive state, hyperglucagonemia, with near maintenance of basal insulin and growth hormone concentrations, stimulates Phe oxidation but not Phe hydroxylation, suggesting a different regulation of these two Phe catabolic steps. Glucagon may also reduce Phe availability for protein synthesis.

[Acute ischemia in myocardial hypertrophy: a report of 2 clinical cases]. / Ischemia acuta nell'ipertrofia miocardica: descrizione di due casi clinici.

We report two cases presented with a clinical picture of acute myocardial ischemia, chest pain and giant negative T waves on electrocardiogram (absent in previous tracings). The echocardiogram B-Mode showed in both cases an asymmetric left ventricular hypertrophy caused, respectively, by hypertrophic cardiomyopathy and hypertensive heart disease. Short-term electrocardiographic evolution to complete normalization was observed in both cases. The echo-dipyridamole test did not show dissynergias and this fact suggested the absence of coronary artery disease; this hypothesis was confirmed by a normal coronary angiography. We suppose that in both patients a few factors contributed to the ischemic events: respectively an acute anemia due to gastric bleeding and high blood pressure values. This clinical presentation is an example of a difficult differential diagnostic problem between left ventricular hypertrophy and acute myocardial ischemia, as it shows that giant negative T waves in hypertrophic cardiomyopathy do not necessarily depend on left myocardial hypertrophy involving the apex or other segments but may be associated to an acute myocardial ischemia related or not to a coronary artery disease. A correct evaluation of these clinical cases is important for clinical, therapeutic and prognostic implications.

The effects of different plasma insulin concentrations on lipolytic and ketogenic responses to epinephrine in normal and type 1 (insulin-dependent) diabetic humans.

This study was performed to verify: (1) the ability of different insulin concentrations to restrict the lipolytic and ketogenic responses to exogenous epinephrine administration; (2) whether the ability of insulin to suppress the lipolytic and ketogenic responses during epinephrine administration is impaired in Type 1 (insulin-dependent) diabetic patients. Each subject was infused on separate occasions with insulin at rates of 0.2, 0.4, and 0.8 mU.kg-1.min-1 while normoglycaemic. To avoid indirect adrenergic effects on endocrine pancreas secretions, the so-called "islet clamp" technique was used. Rates of appearance of palmitic acid, acetoacetate, and 3-hydroxybutyrate were simultaneously measured with an infusion of 13C-labelled homologous tracers. After a baseline observation period epinephrine was exogenously administered at a rate of 16 ng.kg-1.min-1. At low insulin levels (20 microU/ml) the lipolytic response of comparable magnitude was detected in normal and Type 1 diabetic patients. However, the ketogenic response was significantly higher in Type 1 diabetic patients. During epinephrine administration, similar plasma glucose increments were observed in the two groups (from 4.74 +/- 0.53 to 7.16 +/- 0.77 mmol/l (p less than 0.05) in Type 1 diabetic patients and from 4.94 +/- 0.20 to 7.11 +/- 0.38 mmol/l (p less than 0.05) in normal subjects, respectively). At intermediate insulin levels (35 microU/ml) no significant differences were found between Type 1 diabetic patients and normal subjects, whereas plasma glucose levels rose from 4.98 +/- 0.30 to 6.27 +/- 0.66 mmol/l (p less than 0.05) in Type 1 diabetic patients, and from 5.05 +/- 0.13 to 6.61 +/- 0.22 mmol/l (p less than 0.05) in normal subjects. At high insulin levels (70 microU/ml) the lipolytic response was detectable only in Type 1 diabetic patients; the ketogenic response was reduced in both groups. During the third clamp, a significant rise in plasma glucose concentration during epinephrine infusion was observed in both groups. In conclusion this study shows that at low insulin levels Type 1 diabetic patients show an increased ketogenic response to epinephrine, despite their normal nonesterified fatty acid response. Instead, high insulin levels are able to restrict the ketogenic response to epinephrine in both normal and Type 1 diabetic subjects, although there is a still detectable lipolytic response in the latter. In the presence of plasma free insulin levels that completely restrict the ketogenic response in the same group, there is still a distinct glycaemic response. Plasma insulin levels in Type 1 diabetic patients are a major determinant of the metabolic response to epinephrine.

No effects of high-fiber diets on metabolic control and insulin-sensitivity in type 1 diabetic subjects.

The metabolic effects of a three-month treatment with a high-fiber diet (15 grams of guar-gum added to a standard diet) were investigated in seven type 1 diabetic subjects, with a moderately poor metabolic control. HbA1c levels, daily insulin requirement, cholesterol, triglyceride, amino acid and intermediate metabolite concentrations were evaluated before and following the high fiber diet, both in the postabsorptive state at euglycemia and during a euglycemic, hyperinsulinemic, hyperaminoacidemic clamp. Insulin-mediated glucose utilization, an index of insulin-sensitivity, was also measured during the clamp. Following the diet, no differences in HbA1c levels (7.6 +/- 0.7%----7.3 +/- 0.6%), daily insulin requirement (50 +/- 5----51 +/- 3 U/d), triglyceride, amino acid and intermediary metabolite concentrations in the basal, euglycemic state, were observed. Only cholesterol concentrations decreased significantly (from 165 +/- 12 to 142 +/- 12 mg/dl, P less than 0.01) after the diet. During the clamp, the concentrations of all measured substrates were comparable before and after high fiber treatment. Insulin-mediated glucose disposal was also unchanged by guar-gum treatment. Patients' body weights were not modified by the diet. In conclusion, our study shows that a high fiber diet, obtained with the addition of 15 grams of guar-gum to a standard diet, is of no benefit to IDDM either as regards the metabolic control or insulin sensitivity. Only cholesterol levels were decreased. Therefore, the costs and benefits of these diets in the treatment of IDDM should be reconsidered.

Effects of chronic alcohol intake on carbohydrate and lipid metabolism in subjects with type II (non-insulin-dependent) diabetes.

PURPOSE: To study the effects of chronic alcohol intake on carbohydrate and lipid metabolism in subjects with non-insulin-dependent (type II) diabetes (NIDDM). To also evaluate the effect of alcohol withdrawal on metabolic control. PATIENTS AND METHODS: The study group consisted of 46 alcohol-consuming patients with NIDDM (NIDDM-B group), 35 non-alcohol-consuming patients with NIDDM (NIDDM group), and 40 normal control subjects. All patients were admitted to the hospital. Carbohydrate and lipid metabolism was assessed in these individuals immediately on admission to the hospital and during the following days. RESULTS: In the NIDDM-B group, blood alcohol (ethyl alcohol) concentration was very low. However, chronic alcohol intake was associated with higher fasting and postprandial glucose concentrations and higher hemoglobin A1c. No significant differences were found in C-peptide levels. Moreover, higher concentrations of 3-hydroxybutyrate and free fatty acids were observed in the NIDDM-B group than in the NIDDM group. No differences were found in triglyceride concentrations, acid-base patterns, or electrolyte levels. The metabolic effects of alcohol completely waned after 3 days of complete withdrawal. CONCLUSION: Chronic alcohol intake causes deterioration in metabolic control of persons with NIDDM. The effects induced by alcohol are completely reversed after a few days of withdrawal. Strict metabolic assessment is necessary when alcohol is an important constituent of the diet.

Insulin regulation of glucose and lipid metabolism in massive obesity.

Eight obese patients and 12 normal individuals underwent a euglycaemic insulin clamp (20 and 40 mU m2-1.min-1) along with continuous infusion of 3-3H-glucose and 1-14C-palmitate and indirect calorimetry. Basal plasma glucose concentration (4.7 +/- 0.3 vs 4.4 +/- 0.2 mmol/l) was similar in the two groups, whereas hepatic glucose production was slightly higher in obese individuals (1.11 +/- 0.06 vs 0.84 +/- 0.05 mmol/min) in spite of higher plasma insulin levels (17 +/- 2 vs 6 +/- 1 mU/l; p less than 0.01). Insulin inhibition of hepatic glucose production was impaired in obese subjects. Glucose disposal by lean body mass was markedly reduced both at baseline (11.7 +/- 1.1 vs 15.6 +/- 0.6 mumol.kg-1.min-1; p less than 0.05) and during clamp (15.0 +/- 1.1 vs 34.4 +/- 2.8 and 26.7 +/- 3.9 vs 62.2 +/- 2.8 mumol.kg-1.min-1; p less than 0.01) Oxidative (12.2 +/- 1.1 vs 17.8 +/- 1 and 16.1 +/- 1.1 vs 51.1 +/- 1.7 mumol.kg-1.min-1; p less than 0.05-0.002) and non-oxidative glucose metabolism (3.9 +/- 1.1 vs 15.0 +/- 2.8 and 12.8 +/- 3.3 vs 38.2 +/- 2.2 mumol.kg-1.min-1; p less than 0.01-0.001) were impaired. Basal plasma concentrations of non-esterified fatty acids (635 +/- 75 vs 510 +/- 71 mumol/l) and blood glycerol (129 +/- 17 vs 56 +/- 5 mumol/l; p less than 0.01) were increased in obese patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Porcine and human insulin absorption from subcutaneous tissues in normal and insulin-dependent diabetic subjects: a deconvolution-based approach.

The mechanisms of sc insulin absorption are not understood, and models for interpreting in vivo data cannot be developed without gross simplification. To overcome this difficulty we developed a new approach which makes use of deconvolution analysis and does not require any model of the sc tissue. In five normal subjects and seven insulin-dependent diabetic (IDDM) patients endogenous insulin secretion was suppressed by means of a hypoglycemic glucose clamp procedure (approximately 2.8 mmol/L) sustained by a continuous insulin infusion (approximately 4 pmol/min.kg). A bolus injection of insulin (5.4 nmol) was administered iv, and plasma insulin concentrations were measured frequently for 2 h to assess iv insulin kinetics. Insulin then was injected sc in the abdominal region, and plasma insulin concentrations were measured for 8 h. Each subject was studied twice, with porcine and semisynthetic human insulin (Actrapid, Novo). The rate of insulin absorption was reconstructed by deconvolution from the plasma concentrations and iv insulin kinetic data. Linearity of the iv insulin kinetics, essential for deconvolution analysis, was confirmed by a dose-response study in the range of the measured concentrations (150-1800 pmol/L). In most instances, a two-compartment model was adequate to describe the iv response. The mean plasma insulin clearance rates were 15.5 +/- 1.9 (+/- SD) mL/min.kg (porcine) and 17.2 +/- 6.0 (human) in normal subjects and 20.7 +/- 8.8 (porcine) and 20.9 +/- 9.1 (human) in the IDDM patients. The rate of appearance of human insulin from sc tissue was faster than that of porcine insulin in both normal and IDDM subjects, but no significant differences were found in bioavailability, which was 55 +/- 12% (+/- SD; porcine) and 61 +/- 34% (human) in the normal subjects, and 84 +/- 28% (porcine) and 86 +/- 23% (human) in the IDDM patients. The rate of absorption and bioavailability were higher in the IDDM patients than in the normal subjects, a difference possibly related to increased sc blood flow in the IDDM patients. No differences were found with regard to glucose requirement values, normalized to plasma insulin concentrations, in agreement with the finding that the bioavailability of the two insulin species was similar.