Salivary insulin concentrations in Type 2 (non-insulin-dependent) diabetic patients and obese non-diabetic subjects: Relationship to changes in plasma insulin levels after an oral glucose load

Summary The presence of immunoreactive insulin in saliva and its relationship to plasma immunoreactive insulin was investigated in healthy subjects, newly diagnosed non-obese Type 2 (non-insulin-dependent) diabetic patients and obese non-diabetic subjects, basally and after an oral glucose tolerance test. The mean ± SEM fasting values of plasma and salivary immunoreactive insulin were significantly higher in diabetic patients and obese non-diabetic subjects than in normal volunteers (p<0.05). During the glucose challenge, the increase of salivary insulin was related with that of plasma in the three groups of subjects, with a time lag in normal and obese subjects. In normal volunteers, plasma and salivary peak values were respectively 49.5 ± 13.4 U/ml (p<0.05 vs obese subjects) at 60 min and 12.0±3.3U/min (p<0.05 vs obese subjects) at 120 min; in diabetic patients, the values were 51.7 ± 5.6 U/ml (p<0.05 vs obese subjects) and 14.6±4.1 U/min at 120 min; in obese subjects, the peak value for plasma insulin was 111.5±40.1 U/ml at 90 min and for salivary insulin 15.6 ± 5.1 U/min at 120 min. A positive linear relationship was shown between plasma and salivary insulin during the oral glucose tolerance test. The identity of salivary insulin was assessed by reversed-phase HPLC. We conclude that salivary immunoreactive insulin can be found in Type 2 diabetic patients and in obese non-diabetic subjects, as well as normal volunteers, that plasma and salivary insulin are related after a glucose load, and that differences exist in salivary insulin secretion patterns among the three groups of subjects.     

In vitro kinetics of insulin release by microencapsulated rat islets: effect of the size of the microcapsules

Summary Microencapsulation has been proposed to protect islets of Langerhans against immune rejection in xenogenic transplantation. However, to achieve glucose homeostasis in human diabetic patients, insulin release by microencapsulated islets must increase in response to a glucose load. We microencapsulated isolated rat islets using the alginate-polylysine procedure. Capsule size was found to range from 300 to 800 m, and microencapsulated islets were separated according to their size. Groups of 10 microencapsulated islets, either small (350 m) or large (650 m) were placed in plastic microwells, in minimal Eagle's culture medium containing either 5.5 mol/l glucose (basal) or 16.5 mol/l glucose and 5.5 mol/l theophylline (stimulatory medium). The increase in insulin concentration in the surrounding medium was then serially determined over 30 min: (1) With the small capsules, insulin concentration rose from 199 ±20 to 297 ±58 U/ml in basal medium, and from 236 ±23 to 510 ±121 U/ml in stimulatory medium (n = 10 preparations), the difference between the data obtained with the basal or the stimulatory medium being significant (p<0.01) from the 5th min onwards. (2) With large capsules, insulin concentration increased from 182±9 to 266±44 U/ml, and from 216 ±19 to 297 ±34 U/ml in basal and stimulatory medium, respectively, with no apparent significant difference. The magnitude of insulin secretion in response to glucose by unencapsulated islets was, under similar conditions, seven-fold greater. We conclude therefore that the size of the microcapsules is an essential parameter which has to be considered for the optimisation of the microencapsulation procedure.     

Modulation of hepatic glucose production by non-esterified fatty acids in Type 2 (non-insulin-dependent) diabetes mellitus

Summary To study the effect of changes in plasma non-esterified fatty acid concentration on suppression of hepatic glucose production by insulin eight Type 2 (non-insulin-dependent) diabetic patients participated in three euglycaemic, hyperinsulinaemic (108pmol · m^2–1 · min^–1) clamp studies combined with indirect calorimetry and infusion of [3-³H]-glucose and [1-¹⁴C]palmitate; (1) a control experiment with infusion of NaCl 154 mmol/l, (2) heparin was infused together with insulin, and (3) an antilipolytic agent, Acipimox, was administered at the beginning of the experiment. Six healthy volunteers participated in the control experiment. Plasma non-esterified fatty acid concentrations during the insulin clamp were in diabetic patients: (1) 151±36 mol/1, (2) 949±178 mol/l, and (3) 65±9 mol/l; in healthy control subjects 93±13 mol/l. Non-esterified fatty acid transport rate, oxidation and non-oxidative metabolism were significantly higher during the heparin than during the Acipimox experiment (p<0.001). Suppression of hepatic glucose production by insulin was impaired in the diabetic compared to control subjects (255±42 vs 51±29 mol/min, p<0.01). Infusion of heparin did not affect the suppression of hepatic glucose production by insulin (231±49 mol/min), whereas Acipimox significantly enhanced the suppression (21±53 mol/min, p<0.001 vs 154 mmol/l NaCl experiment). We conclude that insulin-mediated suppression of hepatic glucose production is not affected by increased non-esterified fatty acid availability. In contrast, decreased non-esterified fatty acid availability enhances the suppression of hepatic glucose production by insulin.     

Islet B-cell dysfunction and the time course of recovery following chronic overinsulinisation of normal rats

Summary Appropriate insulin therapy may preserve or improve islet B-cell function whereas the effects of overinsulinisation are unclear. Pancreatic islet B-cell function was therefore studied after overinsulinisation of normal rats for 4 weeks (fed blood glucose 2.2–4.5 mmol/l, controls 4.1–7.0 mmol/l). Insulin secretion was assessed by a 3-h hyperglycaemic clamp (10.0 mmol/l) performed 1, 48, and 120 h after insulin withdrawal (n=6 in each group). When the clamp was performed 1 h after insulin withdrawal, clamp insulin concentration was 1.6±0.1 g/l, compared to 9.3±1.0 g/l in control rats. The integrated area under the plasma insulin concentration curve was also significantly decreased (4.8±0.4 vs 20.3±2.2 g·l^–1·h^–1, p<0.001), but recovered to 9.4±1.0 g·l^–1·h^–1 after 48 h, and to 17.5±1.4 g·l^–1·h^–1 after 120 h. Pancreatic insulin contents were decreased at 1 h (6±1 g/g wet wt) and 48 h (54±12 g/g wet wt) but not at 120 h (221±30 g/g wet wt) after withdrawal (controls, 303±29 /g wet wt) and there was a strong relationship with pancreatic preproinsulin mRNA and the clamp insulin response. Thus, overinsulinisation with prolonged periods of low blood glucose concentrations impairs islet B-cell function, but is reversible over 5 days.     

Insulin levels in the umbilical vein and in the umbilical artery of newborns of normal and gestational diabetic mothers

Summary Insulin levels (by double antibody radioimmunological assay) were studied in the venous blood of mothers at vaginal delivery and in the umbilical vein and artery of their newborns. — In 14 normal mothers the insulin levels after 10 hours fasting were 18.5±3.6 U/ml (mean±S.E.M.). In their newborns (mean: 3.420 kg, all < 4.000 kg, 38–41 weeks gestation) the insulin levels were low and similar in the umbilical vein (5.6±0.7 U/ml) and in the umbilical artery (6.6±0.7 U/ml). The plasma glucose levels in the mothers were 99.7±3.9 mg/100 ml and in the umbilical vein 77.3±3.7 mg/100 ml and the umbilical artery 65.5±3.2 mg/100 ml. They were significantly different from each other. — Eleven normal mothers receiving a glucose infusion (ca. 15 g/3 hours) during delivery had 42.0±9.9 U/ml insulin in their venous blood. In their newborns with a normal birth-weight (mean: 3.585 kg, all < 4.000 kg) the insulin levels were not increased either in the umbilical vein (7.0±1.0 U/ml) or in the artery (7.9±1.0 U/ml). The plasma glucose levels in the mothers were 128.0±7.7 mg/100 ml, and in the umbilical vein 105.0±7.5 mg/ 100 ml and in the umbilical artery 88.8±8.6 mg/100 ml. The plasma glucose levels were significantly different from each other. — In six infants with large birthweight (> 4.100 kg) born to untreated mothers with gestational diabetes the insulin levels were superior to the values found in normal newborns. In three of these infants, born to mothers who did not receive a glucose infusion, the insulin levels in the umbilical vein were 38, 42 and 13 U/ml, and in the artery they were 17, 34.5 and 18.5 U/ml. The other three mothers received a glucose infusion, their newborns had in the umbilical vein an insulin level of 15.5, 65 and 19 U/ml and in the artery 20, 72.5 and 14 U/ml. — In conclusion, the normal infant at birth has a low insulin level, which is equal in the umbilical vein and artery. In 6 heavy infants born to untreated latent diabetic mothers, the insulin levels were significantly higher than in normals, and the levels in the umbilical vein and the artery were different from one another. This latter data on hyperinsulinism is discussed in relation with hyperplasia of the islets of Langerhans observed in stillborn infants of mothers with insulin-dependant diabetes or gestational diabetes.Aspirant du Fonds National de la Recherche Scientifique     

Cellular ionic effects of insulin in normal human erythrocytes: a nuclear magnetic resonance study

Summary Elevated erythrocyte cytosolic free calcium, and suppressed free magnesium and pH values are associated with the hyperinsulinaemia and insulin resistance of hypertension, obesity, and Type 2 (non-insulin-dependent) diabetes mellitus. To determine the role of insulin in this process, we utilized ¹⁹F- and ³¹P-nuclear magnetic resonance spectroscopy to study the cellular ionic effects of insulin in vitro on normal human erythrocytes. Insulin elevated cytosolic free calcium levels in a dose- and time-dependent manner. The effect began at 10 U/ml, peaked at 200 U/ml, and continued at both the 500 U/ml and 1000 U/ml doses. At 200 U/ml, free calcium levels rose from 24.6±2.5 nmol/l to a peak value at 120 min of 66.4±11 nmol/l (p<0.05 vs basal), levels remaining elevated throughout the incubation (45.7±5.6 nmol/l at 60 min, and 47.9±9.1 nmol/l at 180 min, p<0.05 vs basal, respectively). Similarly, insulin also increased intracellular free magnesium at all time points (basal: 177± 11 mol/l; 60 min: 209±19 mol/l; 120 min: 206±22 mol/l; and 180 min: 202±12 mol/l; p<0.05 vs basal at all times). No insulin-induced changes in pH were observed. We conclude (i) that insulin in physiological concentrations may participate in regulating divalent cations in the mature human erythrocyte, (ii) that insulin per se cannot account for the previously described cellular ionic lesions of hypertension and diabetes, and (iii) that future clinical studies of cell ion metabolism should be conducted in the fasting state, be controlled for ambient circulating insulin levels, or both.     

Developmental changes in the fatty (fafa) rat: Evidence for defective thermogenesis preceding the hyperlipogenesis and hyperinsulinaemia

Summary Preobese fatty rats have been identified by their lower rectal temperature. Of 51 pups born from matings of heterozygote (Fafa) parents, 16 had low rectal temperatures from day 16 onward (34.6±0.2° C v 35.4±0.3° C) and all subsequently became obese. No animal with the higher normal rectal temperature developed obesity. Hepatic fatty acid synthesis (preobese 0.6±0.1; lean 0.6±0.1 mol/ g/h), hepatic glucose-6-phosphate dehydrogenase activity (G6PDH) (preobese 0.68±0.07; lean 0.71 ±0.03 mol/g/min) and serum insulin (preobese 64 ±2; lean 58±4 U/ml) were unchanged in 18 day preobese, suckling fafa rats. 3 days after weaning hepatic lipogenesis (preobese 25.3±2.0; lean 5.4±0.7 mol/g/h) and G6PDH activity (preobese 4.5±0.5; lean 0.90±0.05 mol/g/min) had increased in both lean and preobese rats although the values attained in preobese rats were significantly greater than in lean rats. When weaning was delayed there was no enhancement in lipogenesis, G6PDH or serum insulin in the preobese rat. The results suggest that the primary genetic defect in fatty rats is not related to the increase in lipogenesis or serum insulin but may reflect a defective thermogenic process.     

Minimal model analysis of insulin sensitivity and glucose-mediated glucose disposal in Type 1 (insulin-dependent) diabetic pancreas allograft recipients

Summary Decreased insulin sensitivity and glucose-dependent glucose disposal (glucose effectiveness) have been demonstrated in poorly-controlled Type 1 (insulin-dependent) diabetic patients. We have therefore examined the effects of successful pancreas transplantation that results in long-term physiologic normoglycaemia as measured by insulin sensitivity index and glucose effectiveness in 14 Type 1 diabetic recipients (Group 1) using the Bergman minimal model method. Their results were compared with those of five non-diabetic patients with kidney transplant alone (Group 2) and 10 healthy control subjects (Group 3). Mean plasma glucose levels were indistinguishable in Group 1 when compared to Groups 2 and 3. However, mean basal plasma insulin levels were two-and eight-fold greater in Group 1 (36±6 U/ml) than in Group 2 (17±7 U/ml) and Group 3 (4.5±0.6 U/ml), respectively. Following intravenous glucose (t=0 min) and tolbutamide (t=20), peak incremental insulin levels were significantly (p<0.001) greater in Group 1 vs Groups 2 and 3. Mean insulin sensitivity index was 65% and 50% lower in Group 1 (2.89±0.45) and Group 2 (4.11±1.30), respectively, when compared to GroupS (8.40±1.24×10^–1 min^–1 (U/ml)^–1. In contrast, glucose effectiveness was similar in the three groups (Group 1, 2.48±0.26; Group 2, 2.05±0.21; and Group 3, 2.10±0.17×10^–2·min^–1). We conclude that, despite prednisone-induced insulin resistance, normal glucose tolerance is achieved by hyperinsulinaemia and normalisation of glucose-dependent glucose disposal following pancreas-kidney transplantation in Type 1 diabetic patients.     

Effects of synthetic rat C-peptide in normal and diabetic rats

Summary The effects of synthetic rat C-peptide 1 and C-peptide 2 on plasma insulin and blood glucose concentrations in the rat were studied. Infusion of rat C-peptide (500g·h^-1· kg^-1) diminished glucose induced increase of plasma insulin by 56% (15.2±0.9 versus 6.6± 0.6 ng/ml, p<0.01, mean±SEM). Somatostatin infused at a rate of 50 g·h^-1·kg^-1 body weight inhibited glucose-induced insulin secretion by 33%. In the presence of a mixture of both C-peptides or somatostatin, blood glucose after intravenous glucose was higher than in the control experiments. In alloxan-diabetic rats, C-peptide (160 g/kg) significantly increased and prolonged the hypoglycaemic effect of exogenous insulin. It is suggested that C-peptide may not be a biologically inert substance.     

The circulating molecular weight forms of infused recombinant insulin-like growth factor-I and effects on glucose and fat metabolism in lambs

Summary We have investigated the relationship between the plasma distribution of infused recominant insulin-like growth factor-I across the insulin-like growth factor binding proteins and the resultant effects on glucose and fat metabolism. The studies were performed in 24-h fasted ram lambs which received primed constant infusions of ³H labelled glucose tracer. When isotopic equilibrium had been reached, the animals received 90-min infusions of human insulin-like growth factor-I at various doses (2.5, 20, 40 and 120 g· kg^–1·h^–1, n=3 for each dose). Total plasma insulin-like growth factor-I was significantly elevated by infusion at a rate of 40 g·kg^–1·h^–1 (from 185±14 g/l to 442±41 g/l, p<0.05) and 120g·kg^–1h^–1 (from 181±2 g/l to 953±39 g/1, p<0.005). The plasma concentrations of insulin-like growth factor-I not associated with binding proteins remained undetectable (<15 g/l) at the end of the 2.5 and 20 g·kg^–1·h^–1 doses, but were significantly elevated at the end of the 40 and 120 g·kg^–1·h^–1 infusions (to 71±14 g/l, p<0.05 and 176±55 g/l, p<0.01 respectively). The infused insulin-like growth factor-I associated primarily with 35–60 kilodalton binding proteins. Glucose kinetics were significantly altered only by the highest dose infusion, during which there was a fall in plasma glucose concentration from 3.5±0.2 mmol/l to 1.9±0.2 mmol/l (p<0.05). This was due to a 51% increase in the rate of glucose clearance. There was no significant change in the rate of glucose production. The plasma concentrations of glycerol and non-esterified fatty acid were not changed by any of the doses infused. We conclude that the hypoglycaemic action of infused recombinant insulin-like growth factor-I relates to a marked elevation of free insulin-like growth factor-I in the plasma, but that a threshold concentration of free insulin-like growth factor-I must be exceeded before this action is observed. The hypoglycaemic action of recominant insulin-like growth factor-I results primarily from an increase in glucose clearance while glucose metabolism was more sensitive than fat metabolism to infused recominant insulin-like growth factor-I. Both these actions contrast with those of insulin, and suggest that the acute metabolic effects of recombinant insulin-like growth factor-I are not mediated simply by cross-reaction with insulin receptors.     

Plasma insulin response in pregnant and non-pregnant rats: Effects of different dietary carbohydrates

Summary The effects of prolonged feeding of diets containing various carbohydrates on the plasma insulin response to glucose (given intravenously) have been investigated in 20-day pregnant rats and compared with the effects in non-pregnant rats. In pregnant animals the insulin response was similar for all diets; the insulin concentration was approximately 120 U/ml for at least 10 min after injecting glucose. In non-pregnant rats, except those fed glucose, the insulin response was lower than in pregnant rats. The mean insulin concentrations were80, 70 and 50 U/ml at 2.5, 5 and 10 min after intravenous glucose. The effect of glucose feeding was to increase the response in non-pregnant animals so that it approached the values found in pregnant animals. The maximum concentrations of plasma insulin for glucose-fed pregnant and non-pregnant rats were 141±23 and 134±15 (SEM) U/ml respectively. It was concluded that the increased availability of glucose in the diet during pregnancy plays a role in regulating the insulin secretory response.     

Untersuchungen zum antilipolytischen Effekt des Insulins am menschlichen Fettgewebe in vitro

Zusammenfassung Am menschlichen Fettgewebein vitro wurde die Hemmung der Lipolyse durch Insulin in glucosefreiem Medium untersucht. Als Parameter der lipolytischen Aktivität wurde die Produktion von Glycerin und freien Fettsäuren bezogen auf Gewebe-Feuchtgewicht gemessen. Die Metabolitfreisetzung durch Fettgewebsschnitte von 25 Normalpersonen betrug in glucosefreiem Medium unter basalen Bedingungen 0.57 ± 0.20 Mol Glycerin/g Gewebe-Feuchtgewicht/2 Std und 2.6 ± 0.8 Eq freie Fettsäuren/g Gewebe-Feuchtgewicht/2 Std — Die Lipolyse wurde durch Zusatz von Noradrenalin oder Adrenalin in Konzentrationen von 0.01 g/ml oder mehr stimuliert. Bei Konzentrationen von 0.1 und 1.0 g Katecholamin/ml ergaben sich submaximale Steigerungen der Metabolitfreisetzung auf rund das Doppelte des Basalwertes. Die mit beiden Hormonkonzentrationen erzielten Effekte waren nicht signifikant unterschiedlich, jedoch bei Noradrenalin signifikant größer als bei Adrenalin. — Zusatz von Insulin zum Inkubationsmedium hemmte die Lipolyse. Durch 33 E Insulin/ml wurde bei Fettgewebsschnitten von 18 Normalpersonen die basale Produktion von Glycerin auf 66 ± 21% und von freien Fettsäuren auf 67 ± 24% reduziert. Auch bei gleichzeitiger submaximaler Stimulation durch Katecholamine betrug die Hemmung der Lipolyse rund 1/3. — Die Konzentration-sabhängigkeit des Insulineffekts auf die Katecholamin-stimulierte Lipolyse wurde an Fettgewebsschnitten von 14 Normalpersonen geprüft. Eine signifikante Lipolyse-hemmung wurde mit einer Konzentration von 1.0 E Insulin/ml im Inkubationsmedium erzielt. Durch 100 E/ml wurde die durch Katecholaminzusatz bedingte Stimulation der Lipolyse aufgehoben. — Diein vitro nachweisbare hohe Insulinempfindlichkeit der Lipolyse des menschlichen Fettgewebes läßt darauf schließen, daß die Fettmobilisation auch unter physiologischen Bedingungenin vivo unabhängig vom Glucosestoffwechsel durch Insulin reguliert wird.

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Investigations of the antilipolytic effect of insulin on human adipose tissue in vitro

Summary The antilipolytic effect of insulin on human adipose tissue was studied employing glucose-free incubation medium. The lipolytic activity was measured by the production of glycerol and free fatty acids, and calculated per g wet weight of tissue. Slices of adipose tissue, which was obtained after an overnight fast from 25 subjects selected for lack of metabolic or endocrine diseases, released 0.57 ± 0.20 moles glycerol/g tissue/2 h, and 2.6 ± 0.8 eq. free fatty acids/g tissue/2 h. — Lipolysis was increased by addition of 0.01 or more g epinephrine or norepinephrine per ml of medium, the increment produced by 0.1 or 1.0 g catecholamine/ml being about 100% of the basal rate. However, the effect of norepinephrine was significantly greater than the effect of epinephrine. — Addition of insulin to the medium inhibited lipolysis. 33 U of insulin per ml decreased the release of glycerol to 66 ± 21 % and the release of free fatty acids to 67 ± 24% of the basal rate. A reduction of lipolysis by about 1/3 was also seen when lipolysis was stimulated by 0.1 or 1.0 g catecholamine per ml. — The dose response of the insulin effect on stimulated lipolysis was studied in slices of adipose tissue from 14 normal subjects. A significant inhibition of lipolysis was demonstrated with 1.0 U of insulin per ml. The lipolytic effect of 0.1 or 1.0 g catecholamine per ml was completely inhibited by 100 U insulin per ml. — The marked insulin sensitivity of lipolysis in human adipose tissuein vitro would be in agreement with the concept, that mobilization of depot fat under physiological conditionsin vivo is regulated by insulin, independent of glucose metabolism.

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Etude de l'effet antilipolytique de l'insuline sur le tissu adipeux humain in vitro

Résumé Les auteurs ont étudié l'effet antilipolytique de l'insuline sur le tissu adipeux humain en utilisant un milieu d'incubation ne contenant pas de glucose. L'activité lipolytique a été mesurée d'après la production de glycérol et d'acides gras libres, et calculée par g de poids humide de tissu. Des coupes de tissu adipeux obtenu à partir de 25 sujets à jeun depuis la veille au soir et n'ayant pas de maladies métaboliques ou endocriniennes, libéraient 0.57 ± 0.20 mol de glycérol/g de tissu en 2 h, et 2.6 ±0.8 Eq d'acides gras libres/g de tissu en 2 h. La lipolyse était augmentée par addition de 0.01 g ou plus d'adrénaline ou de noradrénaline par ml, l'augmentation produite par 0.1 ou 1.0 g de catécholamine/ml étant environ de 100% par rapport au taux de base. Cependant, l'effet de la noradrénaline était significativement plus grand que celui de l'adrénaline. L'addition d'insuline au milieu inhibait la lipolyse. 33 U d'insuline par ml réduisaient la libération de glycérol à 66± 21 % et la libération d'acides gras libres à 67 ± 24% du taux de base. Une réduction de la lipolyse d'environ 1/3 a été également observée quand la lipolyse était stimulée par 0.1 ou 1.0 g de catécholamine par ml. La relation effet-dose de l'insuline sur la lipolyse stimulée a été étudiée sur des coupes de tissu adipeux de 14 sujets normaux. Une inhibition significative de la lipolyse a été constatée avec 1.0 U d'insuline par ml. L'effet lipolytique de 0.1 ou 1.0 g de catécholamine par ml était complètement inhibé par 100 U d'insuline par ml. La sensibilité marquée de la lipolyse à l'insuline dans le tissu adipeux humain in vitro serait en accord avec l'idée que la mobilisation des graisses en dépôt dans les conditions physiologiques in vivo est régulée par l'insuline indépendamment du métabolisme du glucose.

     

A Three-dimensional Analysis of Blood Vessels in Bronchioloalveolar Carcinoma

The three-dimensional architecture of blood vessels within lung adenocarcinomas has not been well studied. In 19 cases with bronchioloalveolar carcinoma with central fibrosis, we three-dimensionally examined blood vessel architecture in 150 m thick sections stained with elastin staining and anti-CD34 antibody. We examined four regions: normal alveoli and three regions within the tumor including an area adjacent to the normal alveoli (external area), an area in which tumor cells were replacing epithelial cells (replacement area), and a central fibrotic area (fibrotic area). Elastin staining showed that elastic fibers formed the framework of the alveoli, and the alveolar structure shrank more strongly to the center of the tumor due to folding of alveolar walls invaded by adenocarcinoma cells. We also measured three vessel parameters in these four regions. The vessel diameters were 4.08±1.10 m, 3.95±1.02 m, 5.04±1.56 m, and 6.11±2.23 m, the circumferences of those vessels seen as complete circles were 43.11±12.78 m, 43.71±12.87 m, 95.21±39.32 m, and 126.77±54.65 m; the lengths between vessel bifurcations were 13.28±3.08 m, 13.47±4.58 m, 24.91±9.66 m, and 41.82±28.08 m in the normal alveoli, and the external, replacement, and fibrotic areas, respectively. Blood vessel architecture changed such that the vessels became larger and coarser towards the center of the tumor. Our three-dimensional analysis suggests continuous remodeling of alveolar capillaries rather than angiogenesis within bronchioloalveolar carcinoma.     

Increased glucose carbon recycling in severely insulin deficient Type 1 (insulin-dependent) diabetic subjects

Summary Six Type 1 (insulin-dependent) diabetic subjects were studied in order to determine the contribution of recycling of glucose carbon to the overproduction of glucose which is characteristic of the fasting hyperglycaemia produced by insulin withdrawal. The subjects were studied on two occasions, once after an overnight insulin infusion and once following 24 h of insulin withdrawal. The difference in turnover rates of 1-¹⁴C-glucose and 3-³H-glucose was used as a measure of glucose recycling. Insulin withdrawal caused a marked metabolic derangement with a rise in non-esterified fatty acids from 0.69±0.23 to 1.11±0.21 mmol/l (mean±SEM, p<0.05), total ketones from 0.27±0.06 to 2.06±0.51 mmol/l (p<0.01), cortisol from 341±43 to 479±31 nmol/l (p<0.05) and growth hormone from 1.1±0.3 to 19+5-mu/l (p<0.05). Glucose turnover rose from 13.8±2.3 mol·kg^–1·min^–1 at a glucose of 6.9±0.7 mmol/l in the insulin infused study to 25.8±4.4 mol·kg^–1·min^–1 (p<0.05) at a glucose of 16.4±0.7 mmol/l in the insulin withdrawn study. Recycling also rose from 3.0±0.4 mol· kg^–1·min^–1 to 9.4±2.2 mol·kg^–1·min^–1 (p<0.05) when insulin withdrawn, accounting for 23±3% and 36±3% of glucose turnover, respectively. We conclude that in the severely insulin deficient Type 1 diabetic subject recycling of glucose carbon is a major contributor to the excess glucose production.     

The effects of parabiosis on serum and kidney glycosidase activities in spontaneously diabetic mice

Summary Spontaneously diabetic non-obese mice of the ICR strain were newly inbred in Shionogi laboratory, Japan. Animals became diabetic suddenly, more frequently and severely in females. Blood glucose levels were 452±73 mg/100 ml with serum insulin levels of < 1.0 U/ml in the fed state. Parabiosis with normal control ICR mice for 2 weeks decreased the blood glucose level to 260±51 mg/ 100ml (P<0.01) and resulted in serum insulin levels of 46.0±18.0 U/ml (P<0.01). Kidney homogenate -N-acetylglucosaminidase and -galactosidase activities were reduced in diabetic mice (42% and 44% decrease respectively) (P<0.025 and P<0.001), and restored almost to normal after 2 weeks of parabiosis. Renal -mannosidase activity was decreased 43% (P<0.001) in the diabetic mice but unaffected by parabiosis. Serum -N-acetylglucosaminidase, -galactosidase and -glucosidase activities were significantly increased in diabetic mice (179%; 233% and 58% increase respectively) (P<0.005, P<0.001 and P<0.001), and returned to normal with parabiosis.     

Acute insulin response of donors is correlated with pancreatic islet isolation outcome in the pig

Aims/hypothesis Unpredictability of islet isolation outcome remains a frustrating and costly issue in the clinical implementation of islet transplantation. The aim of this experimental study was to test the hypothesis that the donors insulin secretory reserve, an in vivo surrogate of functional pancreatic mass, is correlated with the outcome of islet isolation.Methods Insulin secretory reserve was evaluated in 28 healthy adult minipigs prior to pancreatectomy and islet isolation. Blood glucose and insulinaemia were measured before and 1, 3, 5, 10, 15, 30, 60 and 90 min after glucose infusion. Following total pancreatectomy, islet isolation was performed according to Ricordis semi-automated method, and the total number of islets obtained was determined. Fasting blood glucose, insulinaemia, acute insulin response (AIR), maximal insulinaemia and the glucose decay constant (K_G) were calculated, and possible associations with the outcome of islet isolation were assessed.Results AIR and maximal insulinaemia after glucose injection were correlated with the outcome of islet isolation (p<0.01). Mean values for AIR and maximal insulinaemia were significantly different between animals in which islet isolation was successful (n=11) vs those in which it was unsuccessful (n=17) (77.6±13.7 U/ml vs 42.3±7.8 U/ml, p<0.05; 144.7±21.6 U/ml vs 71.9±10.4 U/ml, p<0.05, respectively).Conclusions/interpretation This study suggests that the donors pancreatic endocrine mass, as estimated by AIR, is a major determinant of the outcome of islet isolation in large mammals. Our results may explain the frustrating variability of human islet isolation outcome and could lead to a new approach for optimising the selection of brain-dead and/or living pancreas donors.     

Non-esterified fatty acids do not contribute to insulin resistance in persons at increased risk of developing Type 2 (non-insulin-dependent) diabetes mellitus

Summary The mechanisms underlying insulin resistance in Type 2 (non-insulin-dependent) diabetes mellitus are not fully understood. An enhanced lipid/non-esterified fatty acid oxidation could provide an explanation. To test this hypothesis we examined the relationship between glucose and lipid metabolism in 44 first-degree relatives (28 glucose-tolerant and 16 glucose-intolerant) of Type 2 diabetic patients and in 18 healthy control subjects. Total body glucose disposal was impaired among both glucose-tolerant and glucose-intolerant relatives compared with control subjects (36.3±3.8 and 30.4±2.7 vs 47.7±3.4 mol · kgLBM^/s-1· min^–1; p < 0.05). The impairment in glucose disposal among the relatives was primarily accounted for by impaired non-oxidative glucose metabolism (14.8±3.0 and 12.5±1.8 vs 25.3±3.1 mol · kgLBM^–1 · min^–1; p <0.05). Plasma non-esterified fatty acid concentrations were similar in both glucose-tolerant and glucose-intolerant relatives and control subjects (646±36,649±43 and 615±41 mol/l) and showed the same degree of suppression by insulin (99±8, 86±7 and 84±9 mol/l). Basal lipid oxidation was similar in all groups (1.29±0.09, 1.52±0.13 and 1.49±0.21 mol · kgLBM^–1· min^–1). Furthermore, insulin suppressed lipid oxidation to the same degree in glucose-tolerant, glucose-intolerant relatives and control subjects (0.65±0.13, 0.88±0.15 and 0.59±0.09mol · kgLBM^–1 · min^–1). An inverse correlation between plasma non-esterified fatty acid concentration and total body glucose disposal was observed in the group of control subjects (r=–0.540; p<0.05), but not among the relatives (r=0.002; p=N.S.). In conclusion the present data challenge the view that the glucose-fatty acid cycle contributes to the insulin resistance seen in first-degree relatives of patients with Type 2 diabetes.     

C-reactive protein (CRP) levels in systemic lupus erythematosus (SLE)

Summary CRP levels in 194 serum samples from 43 SLE patients were measured. Patients with inactive disease have levels below 10 g/ml; patients with active SLE have higher levels, but never over 50 g/ml. In the presence of infection or inflammatory processes, regardless of the activity of SLE, the levels are significantly higher (p<0.05), and well over 50 g/ml. Both active SLE patients and inactive SLE patients with local infections have levels between 10 g/ml and 50 g/ml. In this situation, the presence of anti-DNA antibodies strongly suggests disease activity (82% versus 9%, p<0.05). The clinical and physiopathological meaning of these findings is discussed.     

Insulin resistance in Type 2 (non-insulin-dependent) diabetic patients with hypertriglyceridaemia

Summary Hypertriglyceridaemia, which is frequently seen in Type 2 (non-insulin-dependent) diabetes mellitus, is associated with insulin resistance. The connection between hypertriglyceridaemia and insulin resistance is not clear, but could be due to substrate competition between glucose and lipids. To address this question we measured glucose and lipid metabolism in 39 Type 2 diabetic patients with hypertriglyceridaemia, i. e. mean fasting serum triglyceride level equal to or above 2 mmol/l (age 59±1 years, BMI 27.4±0.5 kg/m², HbA_1c8.0±0.2%, serum triglycerides 3.2±0.2 mmol/l) and 41 Type 2 diabetic patients with normotriglyceridaemia, i. e. mean fasting serum triglyceride level below 2 mmol/l (age 58±1 years, BMI 27.0±0.7 kg/m², HbA_1c7.8±0.2 %, serum triglycerides 1.4±0.1 mmol/l). Insulin sensitivity was assessed using a 340 pmol·(m²)^–1· min^–1 euglycaemic insulin clamp. Substrate oxidation rates were measured with indirect calorimetry and hepatic glucose production was estimated using a primed (25 Ci)-constant (0.25 Ci/min) infusion of [3-³H]-glucose. Suppression of lipid oxidation by insulin was impaired in patients with hypertriglyceridaemia vs patients with normal triglyceride levels (3.5±0.2 vs 3.0±0.2mol·kg^–1· min^–1; p<0.05). Stimulation of glucose disposal by insulin was reduced in hypertriglyceridaemic vs normotriglyceridaemic patients (27.0±1.3 vs 31.9±1.6 mol·kg^–1·min^–1; p<0.05) primarily due to impaired glucose storage (9.8±1.0 vs 14.6±1.4mol·kg^–1·min^–1; p<0.01). In contrast, insulinstimulated glucose oxidation was similar in patients with hypertriglyceridaemia and in patients with normal triglyceride concentrations (16.9±0.8 vs 17.2±0.7mol·kg^–1·min^–1). Hepatic glucose production in the basal state and during the clamp did not differ between the two groups. We conclude therefore that oxidative substrate competition between glucose and lipids does not explain insulin resistance associated with hypertriglyceridaemia in Type 2 diabetes. The question remains whether the reduced nonoxidative glucose disposal observed in the patients with hypertriglyceridaemia is genetically determined or a consequence of increased lipid oxidation.     

Effect of insulin on GLUT-4 mRNA and protein concentrations in skeletal muscle of patients with NIDDM and their first-degree relatives

Summary We examined whether insulin resistance, i. e. impaired insulin stimulated glucose uptake in NIDDM patients and their first-degree relatives is associated with alterations in the effect of insulin on the expression of the GLUT-4 gene in skeletal muscle in vivo. Levels of GLUT-4 mRNA and protein were measured in muscle biopsies taken before and after a euglycaemic insulin clamp from 14 NIDDM patients, 13 of their first-degree relatives and 17 control subjects. Insulin stimulated glucose uptake was decreased in the diabetic subjects (19.8±3.0 mol · kg LBM^–1 · min^–1, both p<0.001) compared with control subjects (44.1±2.5 mol · kg LBM^–1 · min^–1) and relatives (39.9±3.3 mol · kg LBM^–1 · min^–1). Basal GLUT-4 mRNA levels were significantly higher in diabetic subjects and relatives compared to control subjects (99±8 and 108±9 pg/g RNA vs 68±5 pg/g RNA; both p<0.01). Insulin increased GLUT-4 mRNA levels in all control subjects (from 68±5 to 92±6 pg/ug RNA; p<0.0001), but not in the diabetic patients (from 99±8 to 90±8 pg/g RNA, NS), or their relatives (from 94±9 to 101±11 pg/g RNA, NS). In the relatives, individual basal GLUT-4 mRNA concentrations varied between 55 and 137 pg/g RNA. Insulin-resistant (n=6, mean glucose uptake rate=30.6±3.4 mol · kg LBM^–1 · min^–1) but not insulin-sensitive relatives (n=7, mean glucose uptake rate=47.4±3.2 mol · kg LBM^–1 · min^–1) had higher basal GLUT-4 mRNA concentrations compared to control subjects (108±9 vs 68±5 pg/ug RNA, p<0.01). GLUT-4 protein content in muscle did not differ between the groups in the basal state and remained unchanged in all groups after insulin infusion. Neither insulin-stimulated GLUT-4 mRNA nor protein concentrations correlated with insulin-stimulated glucose uptake in any of the groups studied. We conclude, that impaired glucose uptake in NIDDM is not related to insulin-stimulated GLUT-4 mRNA or protein concentrations. Acute stimulation of GLUT-4 mRNA by insulin is altered in skeletal muscle of NIDDM patients and their first-degree relatives. This might be a consequence of chronic hyperinsulinaemia elevating basal GLUT-4 mRNA concentrations rather than the cause of insulin resistance.Abbreviations NIDDM Non-insulin dependent diabetes mellitus - GLUT-4 glucose transporter 4 - LBM lean body mass - IDDM insulin-dependent diabetes mellitus