bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-Term Continuous Intravenous Insulin Therapy with a Portable Insulin Dosage-regulating Apparatus
Authors: Irsigler Karl , Kritz Harald
Published: September 2013

A portable insulin dosage-regulating apparatus (PIDRA) was used with five volunteer diabetic subjects for periods ranging from 1 wk to more than 3 months to explore the possibilities of achieving near normoglycemic control over long time periods with such an apparatus. PIDRA consists of a matchbox size pump with insulin reservoir and a pocket size electronic control box. It can infuse a preprogrammed basal rate of insulin plus externally manipulated supplementary doses in rectangular profiles. The quality of blood glucose control was m nitored with the Miles Biostator and through self-testing by the patient in the outpatient phases. Under inpatient conditions, the relatively simple PIDRA insulin administration profile was almost as effective in achieving normoglycemia as the Biostator, and good control could be maintained over long periods of time. The apparatus allows considerably greater ease in variation of insulin dosage with less risk of hypoglycemic episodes as compared with conventional subcutaneous injections. Several technical problems remain to be solved, but it is concluded that PIDRA represents a viable alternative as a means of achieving tight control, at least as a step toward the goal of an implanted glucose-contingent insulin infusion system.
Hyporeninemic Hypoaldosteronism in Diabetes Mellitus: Studies of the Autonomic Nervous System's Control of Renin Release
Authors: Tuck Michael L , Sambhi Mohinder P , Levin Larry
Published: September 2013

The proposal that neurogenic mechanisms may contribute to suppressed plasma renin activity in diabetic patients with hyporeninemic hypoaldosteronism was examined. Five hyperkalemic, diabetic patients with mild to moderate renal insufficiency and evidence of autonomic or peripheral neuropathy were studied. Mean plasma renin (1.1 ± 0.2 ng/ml/h)andaldosterone(2.8 ± 0.8 ng/dl) values were low and showed minimal increase after a low-sodium diet. Sequential renin responses during 4 h upright posture were significantly diminished in all patients compared with control subjects. The normal increment in plasma norepinephrine after upright posture and exercise was also blunted in the patients. Infusion of the beta-adrenergic agonist isoproterenol at a dose to augment pulse rate by 20% of baseline produced a rapid twofold increase in renin in control subjects. The patients had no renin response to isoproterenol infusion at doses that elicited similar cardiovascular responses in both groups. These findings suggest that in hyporeninemic hypoaldosteronism associated with diabetes mellitus and neuropathy, an alteration in sympathetic nervous system activity may contribute to the decreased plasma renin levels. The diminished catecholamine response to upright posture could lead to a blunting of renin response during orthostasis and other maneuvers. Secondly, loss of renin response to isoproterenol infusion in the face of normal cardiovascular responses is consistent with a localized intrarenal defect at the beta-adrenergic receptor level or at more distal sites in patients with hyporeninemic hypoaldosteronism.
Effects of Dichloroacetate on Lipid Metabolism in Isolated Rat Liver Cells
Authors: Misbin Robert I
Published: September 2013

Administration of dichloroacetate (DCA) to normal rats resulted in a fall in serum glucose and triglycerides and a rise in ketone bodies. Insulin and cholesterol levels were unchanged. The effects of DCA on lipid metabolism were examined in isolated rat hepatocytes. At 10 mM DCA, the incorporation of tritiated water into fatty acids (saponifiable lipids) was inhibited by 33 ± 4% (mean ± SEM, N = 5). No effect on incorporation into cholesterol (measured as nonsaponifiable lipids) was observed. DCA inhibited the incorporation of 14C-glucose into lipid but had no effect on glucose oxidation. Fatty acid oxidation was increased by 76 ± 7% (mean ± SEM, N = 6). However, DCA had no effect on the recovery of newly synthesized lipid. Thus, inhibition of tritiated water incorporation into fatty acids represents decreased synthesis rather than increased turnover. DCA did not affect the incorporation of 14C-palmitate into triglycerides or phospholipids. Cell viability, as assessed by incorporation of 3H-isoleucine into protein and trypan blue exclusion, was not affected by DCA. These results suggest that DCA lowers serum triglycerides through inhibition of fatty acid synthesis and stimulation of fatty acid oxidation by liver.
Normalization of the Paradoxic Secretion of Glucagon in Diabetics Who Were Controlled by the Artificial Beta Cell
Authors: Shichiri Motoaki , Kawamori Ryuzo , Abe Hiroshi
Published: September 2013

Since it is important to elucidate the precise significance of pancreatic A-cell hypersecretion in the pathogenesis of diabetes mellitus, the change in the immunoreactive glucagon (IRG) response to 100 g oral glucose challenges was studied in diabetics whose blood glucose responses and plasma immunoreactive insulin concentrations (IRI) simulated those in normal subjects with the aid of the artificial beta cell system that we developed originally.

In six nonobese adult-onset and four insulin-dependent diabetics whose blood glucose responses and plasma insulin concentrations after 100 g oral glucose load were made equivalent to those seen in normal subjects by the artificial beta cell, the glucagon release was similar to the response in normal subjects. In one insulin-dependent diabetic with high anti-insulin-binding capacity, the blood glucose response after an oral glucose challenge was not normalized by the artificial beta cell and the glucagon secretion was paradoxically increased. This fact suggested that the paradoxic rise in glucagon, seen in response to an oral glucose load in some diabetics, is secondary to insulin deficiency.
Intravenous Insulin has no Effect on Transcapillary Escape Rate of Albumin and on Plasma Volume in Short-term Juvenile Diabetics
Authors: Parving H-H , Noer I , Deckert T , Lassen N A
Published: September 2013

The permeability of the microvasculature was studied for the first 50 min after an intravenous injection of between 6 and 10 U of crystalline insulin in seven juvenile diabetics whose mean age was 22 yr. No patient had clinical signs of neuropathy or microangiopathy. The following variables were determined before and after the insulin injection: plasma volume, PV (125I-labeled and 131I-labeled human serum albumin), plasma protein concentration, hematocrit, blood pressure, and pulse rate. PV was measured 40, 45, and 50 min after the insulin injection. Transcapillary escape rate of albumin (TER), defined as the fraction of intravascular mass of albumin that passes to the extravascular space per unit of time, was determined after insulin from the disappearance of the intravenously injected 125I-labeled human serum albumin. The mean blood glucose concentration decreased from 15.1 to 10.8 mmol/L at 50 min after the insulin injection. Blood pressure remained unchanged, while a significant increase in pulse rate occurred after the insulin administration. A reduction in PV, calculated after a mixing period lasting 10 (−3.9%), 15 (−2.3%), and 20 (−1.7%) min, was found after the insulin injection. The last-mentioned difference is not significant statistically. The venous hematocrit remained unchanged; this variable was measured so accurately that a 1% decrease in plasma volume could be excluded with 99% confidence. Plasma protein concentration also remained unchanged. Except the one patient with an extremely high TER (10.6%/h), the remaining six patients had normal TER values after the insulin injection (mean, 5.8; range, 4.5–7.2%/h) compared with our previously investigated control group (mean, 5.4; range, 3.8–7.2%/h) and a comparable group of six short-term juvenile diabetics investigated during good (mean, 5.8; range, 4.4–7.2%/h) and poor (mean, 6.9; range, 5.7–7.7%/h) metabolic regulation (these patients did not receive insulin before the TER determination). In agreement with a previous study, thus, we found a significant reduction in plasma volume and in intravascular mass of protein after a small dose of crystalline insulin intravenously. But the present finding of an unchanged hematocrit and a normal TER does not support the suggestion made in the previous study, viz. that there is an increased transfer of fluid and albumin out of the vascular system. The most likely explanation for the abovementioned reductions is bad mixing (pooling), probably a result of the insulin-induced increase in adrenergic nervous activity, causing vasoconstriction and reduced peripheral blood flow, as demonstrated previously.
Impaired Cardiovascular Responses to Graded Exercise in Diabetic Autonomic Neuropathy
Authors: Hilsted Jannik , Galbo Henrik , Christensen Niels Juel
Published: September 2013

Six juvenile diabetics [age, 31 ± 2 yr (mean and SEM); duration of diabetes, 15 ± 4 yr] with signs of autonomic neuropathy (decreased beat-to-beat variation in heart rate during deep breathing) and seven control patients of similar age (27 ± 1 yr) and duration of diabetes (14 ± 2 yr) performed graded exercise oh an ergometer cycle. Resting heart rate was higher and the increase in heart rate at the lowest work load (50 W) was diminished in patients with autonomic neuropathy compared with control patients (P < 0.001), indicating a vagal defect.

The relationships in autonomic neuropathy between heart rate and systolic blood pressure, respectively, and relative work load (expressed as oxygen uptake — in percent—of individual maximal oxygen uptake) were identical with previous findings in normal subjects during beta-adrenergic receptor blockade, indicating impaired sympathetic activity. Maximal heart rate was 157 ± 9 min−1 in autonomic neuropathy and 181 ± 4 in controls, P < 0.05; maximal systolic blood pressure was 179 ± 11 mm Hg and 197 ± 5, respectively.

The greatest tolerable work load was significantly less in patients with autonomic neuropathy (125 ± 13 vs. 161 ± 9 w, P < 0.05). Similarly, maximal oxygen uptake was reduced (1.68 ± 0.21 vs. 2.78 ± 0.18 L/min, 25 ± 3 vs. 38 ± 2 ml/min/kg, P < 0.005).

In conclusion, diabetics with decreased beat-to-beat variation in heart rate displayed signs of cardiovascular dysfunction of parasympathetic as well as sympathetic origin during graded exercise.
Glycemic Regulation Using a Programmed Insulin Delivery Device: III. Long-Term Studies on Diabetic Dogs
Authors: Goriya Yoshikazu , Bahoric Andrej , Marliss Errol B , Zinman Bernard , Albisser A Michael
Published: September 2013

Long-term glycemic normalization in diabetic dogs has been achieved using a portable insulin delivery device. Six pancreatectomized male dogs carried the device for periods of 7 ± 2 (range –12) mo. Pulses of insulin were delivered every 90 s into the inferior vena cava through an exteriorized indwelling catheter In the postabsorptive period, insulin was infused at the mean rate of 0.44 ± 0.03 mU/min/kg and glycemia was 93 ± 7 mg/dl, while in the postprandial period insulin was infused for 7 h at the mean rate of 3.10 ± 0.22 mU/min/kg. A standard daily diet was provided, and the resulting glycemic profiles were similar to an age-, sex-, and weight-matched group of six healthy controls.

Peripheral insulin levels in the infused diabetic dogs (15 ± 1 μU/ml) were not significantly different from nondiabetic controls in the fasting state and were unresponsive to caloric provocation. However, in the postprandial period of enhanced delivery, insulin levels in the diabetic dogs were two to four times higher than in the controls.

Unaccountable episodes of hypo- or hyperglycemia did not occur. Techniques for long-term vascular access were developed such that catheter-related complications, including infection and thrombosis, were not encountered.

This study demonstrates the feasibility of long-term glycemic control in unrestrained diabetic animals using a preprogrammed waveform of insulin delivery. Hyperinsulinism accompanies the glycemic normalization when the hormone is delivered peripherally.
Correction of Ketosis by Suppression of Lipolysis with 5-Methylpyrazole-3-Carboxylic Acid in Rats with Established Diabetic Ketoacidosis
Authors: Axelrod Lloyd , Lloyd-Jones Peter , Martin Donald B
Published: September 2013

Because the presence of an elevated plasma free fatty acid (FFA) concentration is not always sufficient to promote ketogenesis, we examined the contribution of circulating FFAs to ketogenesis in established diabetic ketoacidosis. We studied the effects of suppression of lipolysis on ketogenesis in rats with established streptozotocininduced diabetic ketoacidosis using 5-methylpyrazole-3-carboxylic acid (5-methylpyrazole) as an antilipolytic agent. In response to this substance, plasma FFA fell from 2.42 ± 0.15 meq/L to 0.56 ± 0.06 meq/L in four hours. There was a concomitant fall in total plasma ketone from 12.17 ± 0.60 mM to 2.62 ± 0.54 mM. The fall in total plasma ketone was due predominantly to a fall in the beta-hydroxybutyrate concentration but also to a fall in the acetoacetate concentration. Although the agent slowed the rise of plasma glucose in these diabetic animals, the concentration was markedly elevated (573 ± 22 mg/dl) at four hours.

Studies were performed in comparable rats with diabetic ketoacidosis to exclude the possibility that 5-methylpyrazole interferes with hepatic ketogenesis. When the plasma FFA concentration was raised by administration of a lipid emulsion and heparin (after plasma FFA and total plasma ketone had fallen in response to 5-methylpyrazole), total plasma ketone also rose despite the presence of 5-methylpyrazole. When the plasma FFA concentration was maintained at a high level by administration of a lipid emulsion and heparin from the start of the experiment, 5-methylpyrazole failed to affect the total plasma ketone concentration. Thus, availability of substrate (plasma FFAs) reversed or prevented the correction of ketosis by 5-methylpyrazole.

These findings indicate that circulating FFAs are rate limiting for the maintenance of the ketotic state in established diabetic ketoacidosis and support the view that the absence of ketosis in the usual patient with hyperosmolar nonketotic diabetic coma is a result of inadequate availability of plasma FFAs for ketogenesis. 5-Methylpyrazole converts an experimental model of diabetic ketoacidosis into one resembling hyperosmolar nonketotic diabetic coma.
Studies of the Effects of an Elevated Glucose Concentration on the Ultrastructure and Composite Metabolism of the Intact Rabbit Aortic Intima-Media Preparation
Authors: Morrison Anthony D , Orci Lelio , Perrelet Alain , Winegrad Albert I
Published: September 2013

To assess whether the ultrastructure and composite metabolism of the arterial wall are subject to acute modification by exposure to an elevated glucose concentration, paired samples of the intact rabbit aortic intima-media preparation were incubated with 5 mM or 20 mM glucose for 1 h under conditions in which the ultrastructural and metabolic stability of samples incubated with 5 mM glucose has previously been demonstrated. Incubation with 20 mM glucose did not alter the qualitative electron-microscopic appearance of the tissue, and no significant changes were found on a quantitative morphometric evaluation of the aortic endothelium. A detectable, composite-free intracellular glucose concentration was not demonstrable in samples incubated with 5 mM or 20 mM glucose by a comparison of the ratio of glucose space:inulin space. Samples incubated with 5 mM glucose had significant sorbitol concentrations and unexpectedly high fructose concentrations but did not release fructose into the medium at detectable rates. Incubation with 20 mM glucose resulted in an increase in tissue sorbitol without an increase in tissue fructose or a detectable rate of fructose release. Tissue water content and myoinositol concentration were unaltered by incubation with 20 mM glucose, as were the rates of O2 uptake and lactate production whether the gas phase was 5% CO2:95% O2 or 5% CO2:95% air. The ultrastructure' of intact aortic intima-media is not acutely altered by exposure to an elevated glucose concentration. Ambient glucose concentration is not the primary determinant of composite-free intracellular glucose concentration in arterial wall, and an increase in medium glucose concentration does not result in a significant increase in glucose utilization via the polyol pathway or induce the concomitants of increased polyol pathway activity demonstrable in a conventionally prepared aortic intima-media preparation.
Metabolic Control in Diabetic Patients: Effect of Insulin-secretory Reserve (Measured by Plasma C-Peptide Levels) and Circulating Insulin Antibodies
Authors: Gonen Boas , Goldman Jose , Baldwin David , Goldberg Ronald B , Ryan Will G , Blix Petra M , Schanzlin David , Fritz Karl J , Rubenstein Arthur H
Published: September 2013

We measured circulating hemoglobin A1 (HbA1) and fasting plasma C-peptide concentrations in 100 diabetic patients. Pancreatic insulin reserve showed a negative correlation with HbA1 concentrations in nonobese, insulin-treated patients but not in obese patients, whether they were treated with insulin, oral agent, or diet alone. Patients with fasting C-peptide concentrations above 0.1 pmol/ml had significantly better metabolic control than did those with lower values.

Anti-insulin antibodies were measured in 37 patients. There was no correlation between metabolic control and the affinity constants or binding capacities of these antibodies.
Method for Large-Scale Isolation of Pancreatic Islets by Tissue Culture of Fetal Rat Pancreas
Authors: Hellerström Claes , Lewis Nancy Jo , Borg Håkan , Johnson Robert , Freinkel Norbert
Published: September 2013

Detailed studies of the maturation of stimulus-secretion coupling of the pancreatic B-cell requires a supply of isolated fetal islets, which has so far been difficult to obtain. To overcome this problem we have maintained minced and mildly collagenase-digested fetal rat pancreatic glands (21.5 days gestational age) in tissue culture to enable degeneration of the acinar part, leaving the endocrine cells in an isolated and surviving state. Indeed, after 1 wk in culture there was a complete separation between acinar and endocrine cells with the appearance of numerous discrete islets and the disappearance or dedifferentiation of the exocrine cells. Isolated islets were either free floating or attached on top of a monolayer of fibroblast-like cells. Their number after 1 wk in culture was estimated as about 90 per explanted fetal pancreas and a total yield of about 5000 isolated islets was easily achieved. Both light arid electron microscopic examinations showed an excellent structural preservation with a marked predominance of well-granulated B-cells. Numerous islets of the same weight as that measured in cultured islets of adult rats were regularly found after 1 wk in culture. The insulin concentration of the cultured fetal islets was related to the glucose concentration of the growth medium. A similar relationship was found with respect to the insulin release in response to glucose. Thus, fetal islets cultured for 8 days in growth media containing 11.1 or 22.2 mM glucose showed a marked and significant insulin response to glucose in batch-type incubations at the end of the culture period. By contrast, the glucose stimulation of insulin release was insignificant in islets cultured at 5.5 or 2.8 mM glucose. When the culture period was confined to 1 day, there were no effects of glucose on the insulin release irrespective of the glucose concentration of the growth medium.

It is concluded that the present technique for tissue culture of fetal rat pancreas makes it possible to isolate substantial amounts of fetal islets predominantly composed of B-cells. The transition in vitro from a poor glucose sensitivity to an adult-type insulin response indicates that the technique can be used in further detailed studies of the molecular mechanisms involved in the growth and development of the pancreatic B-cell.
Effect of Diet-induced Obesity on Glucose and Insulin Tolerance of a Rodent with a Low Insulin Response (Acomys cahirinus)
Authors: Gutzeit Arndt , Renold Albert E , Cerasi Erol , Shafrir Eleazar
Published: September 2013

Spiny mice (Acomys cahirinus) from the Geneva colony tend to develop diabetes, whereas those maintained in Jerusalem do not. The role of environmental factors in the development of glucose intolerance was investigated by diet exchanges in specimens from the two colonies. Spiny mice on the Geneva diet (laboratory chow supplemented by a seed mixture containing 15% fat by weight) developed massive obesity over 8–10 months; body lipid content increased threefold compared with albino mice and was twofold higher than in spiny mice maintained on the laboratory chow in Jerusalem or in spiny mice living in their natural habitat near the Dead Sea. Spiny mice from the Geneva colony, kept on the laboratory chow alone, were as lean as animals from the Jerusalem colony. Similarly, Jerusalem Acomys given pellets supplemented by seeds developed marked obesity. Liver and adipose tissue enzymes in spiny mice transferred to the seed-supplemented diet showed adaptation typical for fat feeding: decrease in the capacity of glycolysis, NADPH generation, and fatty acid synthesis.

The obesity was associated with insulin resistance, evident from a negative correlation between the extent of hypoglycemia after i.v. insulin administration and body lipid content. The glucose disappearance rate (K value) was significantly reduced by obesity, but the insulin response to i.v. glucose increased only moderately. In all the Acomys groups studied, insulin response to i.v. glucose was markedly lower in comparison with the response in albino mice.

The following conclusions are drawn: (1) Low insulin response to glucose is a species-characteristic of spiny mice whether the animals are bred in laboratories or live in freedom. (2) Given an appropriate diet, spiny mice develop obesity, accompanied by pronounced insulin resistance. (3) Obesity may be one of the causes of the marked islet hyperplasia in laboratory-kept spiny mice, but this does not result in increased insulin output. (4) The inability of spiny mice to respond with augmented insulin secretion when insulin efficiency is reduced may be responsible for the accelerated development of glucose intolerance in this species. Thus, the liability of Geneva spiny mice to develop diabetes may be caused by the obesity-inducing diet used in this colony rather than to a specific genetic characteristic. (5) The fact that insulin resistance in spiny mice occurs without the development of hyperinsulinemia suggests that similar mechanisms may operate in the development of glucose intolerance in human, low, insulin responders.
The Association Between Diabetic Retinopathy and Skeletal Muscle Capillary Basal Lamina Thickening Corrected for the Influence of Age and Duration of Diabetes
Authors: Dunn P J , Donald R A , Day T , Stewart J M , Stewart A W
Published: September 2013

The association between an objective measure of diabetic retinopathy and skeletal muscle capillary basal lamina thickness was examined in a group of 30 male insulin-treated diabetic subjects, mean age (±SD) 44.6 ± 13.2 yr, duration of diabetes 21.2 plusmn; 11.2 yr, % ideal body weight (% IBW) 106 ± 11%. In addition, muscle capillary basal lamina width was measured in a group of 18 nondiabetic men, mean age 40.7 ± 16.3 yr and % IBW 118 ± 23%. The muscle capillary width of the diabetic subjects was significantly greater than that of the nondiabetic group (P < 0.01), but the values of the two overlapped considerably. In the diabetic group, there was a significant association of basal lamina width with age (P < 0.01) but not with duration of diabetes. The association between extent of retinopathy and muscle capillary basal lamina width was not strong. The findings of the study do not therefore support the use of an estimate of muscle capillary basal lamina thickness as a single representative measure of diabetic microangiopathy.
Somatostatin Concentration Responds to Arginine in Portal Plasma: Effects of Fasting, Streptozotocin Diabetes, and Insulin Administration in Diabetic Rats
Authors: Kazumi Tsutomu , Utsumi Masafumi , Yoshino Gen , Ishihara Kazuhide , Hirose Yoshikazu , Makimura Hiroyuki , Baba Shigeaki
Published: September 2013

Changes of somatostatin concentration in response to a single i.v. injection of arginine (400 mg/kg body weight) were examined in extracted portal plasma of normal and diabetic rats in the fully fed state and after 24 h of fasting, as well as in diabetic rats treated with insulin for one week. In both normal and diabetic animals fasted for 24 h, the basal level of somatostatin declined but the magnitude of the arginine-induced elevation of somatostatin was not affected, suggesting a physiologic role of the tetradecapeptide in nutrient homeostasis.

When compared with intact rats, diabetic animals were shown to have increased levels of somatostatin before and after arginine administration, both of which were attenuated by insulin replacement therapy. These findings suggest that alterations of D cell function in streptozotocin diabetes may be related to either insulin deficiency or its metabolic consequences.
Stimulation of Adenylate Cyclase by Ca2+ and Calmodulin in Rat Islets of Langerhans: Explanation for the Glucose-induced Increase in Cyclic AMP Levels
Authors: Sharp Geoffrey W G , Wiedenkeller Dayna E , Kaelin Denise , Siegel Eberhard G , Wollheim Claes B
Published: September 2013

The effect of Ca2+ and calmodulin has been studied on adenylate cyclase activity in homogenates of rat islets of Langerhans. EGTA had a stimulatory effect on the enzyme in accord with the known inhibitory effect of Ca2+. In contrast, the addition of Ca2+ together with calmodulin is stimulatory and demonstrates the existence of a Ca2+-dependent adenylate cyclase in islets of Langerhans. It is suggested that the glucose-induced increase in cyclic AMP concentrations in intact islets is a secondary consequence of the glucose-induced increase in cytosol free-Ca2+ concentrations which, with calmodulin, causes an increase in the activity of adenylate cyclase.
Transplantation of Dispersed Pancreatic Islet Tissue in Humans: Autografs and Allografts
Authors: Sutherland David E R , Matas Arthur J , Goetz Frederick C , Najarian John S
Published: September 2013

Islet transplantation is successful in animals and holds considerable promise as endocrine replacement therapy for patients with diabetes mellitus, but clinical application to diabetic patients has been difficult. We have shown the technical feasibility of human islet transplantation by autotransplantation of dispersed pancreatic islet tissue into the portal vein in three patients with chronic pancreatitis and incapacitating, intractable pain who underwent near-total (>97%) pancreatectomy. In all three patients, the excised pancreas was dispersed by collagenase digestion, but no effort was made to purify the islets. Islet yield, as judged by tissue insulin content, ranged from 24 to 55%. The first patient, who never received insulin after the pancreatectomy and islet autotransplantation, had a normal oral glucose tolerance test by 3 wk and has remained normoglycemic for over 2 yr. In the second patient, viable islets were histologically identified in the liver parenchyma. The third patient was treated with hyperalimentation for 3 wk after the pancreatectomy and islet autotransplantation and, during this period, required insulin. After cessation of hyperalimentation and initiation of oral feedings, the patient was withdrawn from insulin. Although abnormalities of carbohydrate metabolism were present, the patient did not require insulin for more than 1 yr.

Seven diabetic renal eliografi recipients have received allografts of dispersed pancreatic islet tissue prepared in the same way. No patients were cured of diabetes, although transient evidence of islet function —increase in serum or urinary C-peptide levels or decrease in exogenous insulin requirements— occurred in some. Although rejection was probably responsible for most of the failures, transplantation of allogeneic human islet tissue as a free graft is metabolically inefficient. With the current state of immunosuppressive therapy, the primary role of islet transplantation may be in a situation where rejection cannot occur: as an autograft to obviate the occurrence of diabetes after extensive pancreatectomy for benign disease.
Quantitative Estimation of Beta Cell Sensitivity to Glucose in the Intact Organism: A Minimal Model of Insulin Kinetics in the Dog
Authors: Toffolo Gianna , Bergman Richard N , Finegood Diane T , Bowden Charles R , Cobelli Claudio
Published: September 2013

We propose an approach to quantifying the sensitivity of B cells to glucose in the intact organism, whereby we interpret the complex dynamic plasma insulin response to glucose injection in terms of a minimal mathematical model of posthepatic insulin delivery and insulin clearance. The best model for this purpose was chosen by comparing the ability of a series of proposed models to account precisely for plasma insulin dynamics. Intravenous glucose tolerance tests (IVGTT) (300 mg/kg) were performed on conscious dogs, and blood was sampled frequently until the basal steady state was reestablished. Glucose injection produced variable plasma insulin responses, which were characterized by an early peak (76 μU/ml above basal), a plateau with occasional additional peaks, and by an abrupt return of plasma insulin to basal by 37 min. A set of eight models was examined; one emerged as superior, in that it was able to account for insulin dynamics with the smallest number of physiologically meaningful parameters (N = 4). The chosen (minimal) model assumes that (1) clearance of insulin is of the first order, (2) the initial peak represents a bolus of insulin loaded into the plasma after the glucose injection, and (3) the rate of the secondary rise in insulin is determined by the concentration of glucose in plasma above a specific threshold value. The sensitivity of first phase insulin delivery to glucose (φ1; 1.28 ± 0.15 μU/ml per min per mg/dl), the sensitivity of the secondary phase to glucose concentration [φ2; 0.038 ± 0.005 (μU/mg) · min−2], and the threshold for glucose stimulation of second phase secretion (h; 125 ± 8 mg/100 ml) were all precisely estimated from the dynamic insulin responses.These three parameters of insulin kinetics (φ1,φ2, and h) can be calculated from a single IVGTT, and theycharacterize the insulin responsivity of a single individual. Estimating these characteristic parameters of insulin kinetics from IVGTT data has potential for quantitating the individual factors contributing to glucose-stimulated insulin secretion in intact animal models, and it may be applicable to man.
Development of Adipose Tissue in Newborns of Gestational-diabetic and Insulin-dependent Diabetic Mothers
Authors: Enzi G , Inelmen E M , Caretta F , Villani F , Zanardo V , DeBiasi F
Published: September 2013

Some parameters of adipose tissue development have been studied in normal, full-term infants of gestational-diabetic mothers (GDM) and insulin-dependent diabetic mothers (IDDM). Values of skinfold thickness, body fat mass, and fat cell weight in full-term newborns of GDM and IDDM are greater than in infants of nondiabetic mothers. Fat mass enlargement in newborns of diabetic mothers seems to be caused almost exclusively by an increase in the triglyceride content of the single adipocytes. Results of determinations of fat cell weight are in fact significantly higher in newborns of GDM and IDDM and correlate closely with skinfold thickness and body fat mass: No differences resulted in the approximate estimate of fat cell number. Neither maternal weight gain during pregnancy nor pregravidic overweight seem to be directly related to the expansion of adipose tissue observed in newborns of diabetic mothers. Maternal blood glucose levels and neonatal IRI levels in cord blood significantly correlated with fat cell weight. Maternal FFA levels are not related to parameters of adipose tissue development in newborns of normal, GD, and IDD mothers.

In conclusion, enlargement of body fat mass in full-term infants of GDM and IDDM is dependent on glucose availability and, thus, on the insulin-induced enhancement of triglyceride synthesis and storage in single adipocytes. Free fatty acids do not seem to play an important role in regulating the triglyceride content of fat cells in newborns of gestational-diabetic or insulin-dependent diabetic mothers.
A Decreased Response of Cyclic Adenosine Monophosphate Concentrations to Glucagon in Liver Slices from Streptozotocin-induced Diabetic Rats
Authors: Yamashita Kamejiro , Yamashita Somo , Yasuda Hiroko , Oka Yuji , Ogata Etsuro
Published: September 2013

Responses to glucagon from the adenylate cyclasecyclic adenosine monophosphate (cAMP) system in liver slices from control and streptozotocin-induced diabetic rats were compared. Tissue cAMP levels were similar in the basal state but responded poorly to glucagon (20 pg/ml-2 μg/ml) in diabetic rats. Insulin treatment of diabetic rats in vivo led to a reversal of the glucagon stimulation towards the values in the control rats. The basal and glucagon-stimulated activities of adenylate cyclase in crude membrane fractions were similar in both groups.

Plasma immunoreactive glucagon levels in diabetic rats were approximately three times higher than those in normal rats.

Liver slices obtained from normal rats, which were injected with glucagon (0.2 mg, i.m.) 45 min previously, also showed an impaired responsiveness to glucagon of tissue cAMP levels, while no significant difference in adenylate cyclase activity was observed between the normal and glucagon-treated rats.

These results suggest that the responsiveness of liver slices from the streptozotocin-induced diabetic rat has been modified by the preceding hyperglucagonemia. The reason for the observed differences between slices and crude membranes is not known.
HbA1 in Subjects with Abnormal Glucose Tolerance but Normal Fasting Plasma Glucose
Authors: Bolli Geremia , Compagnucci Pietro , Cartechini Maria G , Santeusanio Fausto , Cirotto Carlo , Scionti Luciano , Brunetti Paolo
Published: September 2013

HbA1(a+b+c)(HbA1) was determined chromatographically in 107 subjects with normal fasting plasma glucose (FPG) and 112 patients with overt diabetes. Subjects with normal FPG were divided into two groups based on their response to two oral glucose tolerance tests (OGTTs), at an interval of 2 mo. In 40 subjects with normal OGTT (group I), HbA1 ranged from 5.2% to 7.2%, while in 67 subjects with abnormal OGTT (group II), it ranged from 6.3% to 9.6%. HbA1 levels were significantly higher in group II than in group I (7.7 ± 0.09% versus 6.4 ± 0.08%, mean ± SEM, P < 0.0005), but 14 subjects of group II had HbA1 levels less than 7.2%. No correlation was found between HbA1 and FPG, OGTT peak, and curve area in either group. However, the correlation became significant in all 107 subjects with normal FPG (groups I + II). In patients with overt diabetes, HbA1 ranged from 6.3% to 18% (11.9 ± 0.22%) and correlated with FPG (r = 0.78, P < 0.0005).

The traditional OGTT seems more sensitive than the HbA1 measurement in detecting subjects with reduced carbohydrate tolerance. HbA1 level, on the other hand, is known to be a more specific indicator of structural abnormalities following long-term hyperglycemia. Thus HbA1 determination might be a helpful test along with OGTT to improve both selection and follow-up of subjects with true borderline diabetes.
Potentiation of Insulin Secretion to Nonglucose Stimuli in Normal Man by Tolbutamide
Authors: Pfeifer Michael A , Halter Jeffrey B , Graf Ron , Porte Daniel
Published: September 2013

To determine how sulfonylureas affect beta cell function, insulin release in response to isoproterenol and arginine was assessed in 32 normal subjects before and during a tolbutamide infusion. When the plasma glucose was allowed to decrease during tolbutamide, the acute insulin response (AIR) to isoproterenol was not changed (AAIR = −4 ± 8 μU/ml, ± SEM, n = 8, p = NS) and was enhanced slightly for arginine (ΔAIR = +61 ± 26 μU/ml, n = 6, p < 0.05). When plasma glucose levels were maintained by means of a concomitant variable glucose infusion during tolbutamide, the insulin responses to both isoproterenol and arginine were enhanced (isoproterenol: ΔAIR = +55 ± 15 μU/ml, n = 6, P < 0.001; arginine: ΔAIR = +137 ± 34 μU/ml, n = 8, P < 0.001). Regression analysis demonstrated a linear relationship between change in the prestimulus glucose level and the change in the AIR to isoproterenol during tolbutamide (r = 0.66, n = 14, P < 0.02). Since the slope of this relationship is not significantly different from a similar relationship in the absence of tolbutamide, the potentiating effect of tolbutamide is an amplification of an established physiologic relationship. We conclude that tolbutamide augments the insulin response to nonglucose stimuli. However, this potentiating effect of tolbutamide may be masked by a decrease in the prestimulus glucose level.
Effect of Adrenergic Agents on the Secretion of Gastrointestinal Immunoreactive Glucagon in Depancreatized Dogs
Authors: Yoshida Toshihide , Kondo Motoharu
Published: September 2013

To elucidate the mode of action of adrenergic agents on gastric A cells, the effects of infusion of adrenergic agonists and antagonists on the secretion of gastrointestinal immunoreactive glucagon (gastrointestinal IRG) from gastric A cells were investigated in 45 conscious, depancreatized dogs untreated with insulin.

Large amounts (0.6 μg/kg/min) of epinephrine, norepinephrine, and isoproterenol stimulated the release of gastrointestinal (RG, and catecholamine-induced gastrointestinal IRG release was completely abolished by simultaneous infusion of the specific beta receptor-blocking compound, propranolol, but not by alpha receptor blockade with phentolamine.

These findings suggest that, when adrenergic agonists are infused in large amounts, they may act through a beta receptor to increase the release of gastrointestinal IRG.
Pirogliride: An Oral Hypoglycemic Drug Which Accelerates Glucose Usage and Insulin Secretion by Islets of Langerhans
Authors: Zawalich Walter S , Weill Victoria A , Matschinsky Franz M
Published: September 2013

Pirogiiride potentiates glucose-induced insulin secretion from isolated islets. This effect is accompanied by a facilitated glucose metabolism. Pirogliride partially prevents the known inhibitory effects of mannoheptulose on glucose-induced secretion and utilization. Pirogliride might be useful not only to probe the underlying mechanism of stimulated insulin secretion but also in the therapy of those diabetics who have an impaired β-cell responsiveness to glucose.
The Stimulus-secretion Coupling of Amino Acid-induced Insulin Release: Metabolism and Cationic Effects of Leucine
Authors: Malaisse Willy J , Hutton John C , Carpinelli Angelo R , Herchuelz André , Sener Abdullah
Published: September 2013

When isolated rat pancreatic islets are exposed to L-leucine (20 mM), the rate of NH4 production is close to the summed rates of L-[1-14 C] leucine decarboxylation and α-ketoisocaproate production, whereas the rates of acetoacetate production and L-[U-14 C]-leucine oxidation are compatible with the conversion of each mole of the amino acid to one mole of acetoacetate and three moles of CO2. ATP content, ATP/ADP ratio, and adenylate charge are maintained at normal values by L-leucine, whereas the NADH/NAD+ ratio (but not the NADPH/NADP+ ratio) is significantly increased. The release of insulin evoked by L-leucine is potentiated by 2-ketoisovalerate, unaffected by L-valine, and inhibited by menadione. L-leucine mimicks the effect of D-glucose on 86Rb+ and 45Ca2+ handling by the islets. However, relative to its rate of oxidation, the insulinotropic effect of L-leucine is less marked than that of D-glucose. This may be due, in part at least, to a decrease in the oxidation of endogenous nutrients. It is concluded that the metabolic, cationic, and secretory effects of L-leucine in isolated islets are not incompatible with the fuel hypothesis for insulin release.
Immunohistochemical Localization of Aldose Reductase: I. Enzyme Purification and Antibody Preparation—Localization in Peripheral Nerve, Artery, and Testis
Authors: Ludvigson Mark A , Sorenson Robert L
Published: September 2013

Aldose reductase (AR) was purified from rat and bovine seminal vesicles using DEAE-cellulose, hydroxylapatite, and Sephadex-gel column chromatography. The purification resulted in the obtention of an AR pool and a contaminating pool. Antibodies were raised in rabbits against both enzymes by subcutaneous injection of the AR pool. The antisera was judged to be specific for AR by immunoprecipitation of AR activity and by Ouchterlony double immunodiffusion and immunoelectrophoretic methods. Antibodies against rat AR were used in the unlabeled antibody-enzyme (PAP) technique to demonstrate the cellular location of the enzyme in a number of tissues known to be sites of diabetic lesions. Antibodies against bovine AR were not cross reactive with the rat enzyme, as determined by Ouchterlony and competitive protein-binding studies. AR was localized in rat tissues to the Schwann cell sheath of peripheral nerve, arterial endothelium, and the sustentacular (Sertoli) cells and mature spermatids of the testis.
Acute Changes in Brain Tryptophan and Serotonin After Carbohydrate or Protein Ingestion by Diabetic Rats
Authors: Crandall Elizabeth A , Fernstrom John D
Published: September 2013

In normal, fasting rats, intubation with glucose did not alter serum tryptophan, but it did reduce serum concentrations of the large neutral amino acids, tryptophan's competitors for brain uptake. The serum ratio of tryptophan to the sum of these competitors, which predicts brain tryptophan uptake, was thus increased. Brain tryptophan, serotonin (which is synthesized from tryptophan), and 5-hydroxyindoleacetic acid levels also increased. Such increases in brain serotonin are potentially important, since serotonin is a neurotransmitter. Changes in its level may indicate altered release by neurons and, thus, modified brain function. In contrast, glucose intubation of fasting streptozotocindiabetic rats elicited only a small increase in the serum tryptophan ratio. Brain tryptophan increased slightly; no changes occurred in brain serotonin or in 5-hydroxyindoleacetic acid. Similar effects were noted when fasting diabetic rats consumed a single, carbohydrate meal. However, brain indoles did increase after carbohydrate ingestion in diabetic rats that received an insulin injection at the time food was presented.

Effects of ingesting a protein-containing meal were also studied. In normal rats, consumption of this meal increased the serum tryptophan ratio slightly. Brain tryptophan and serotonin levels were unchanged. In diabetic rats, ingestion of the protein-containing meal often lowered the serum tryptophan ratio. Brain tryptophan also fell in diabetic rats when the serum tryptophan ratio was reduced, but brain 5-hydroxyindoles did not fall.

The data demonstrate that the absence of a carbohydrate-induced increment in brain indole levels follows indirectly from the absence of the insulin-induced rise in the serum tryptophan ratio. The diabetic rat's inability to experience normal carbohydrate-induced increments in brain serotonin suggests that brain functions, normally dependent on such neurochemical signals, may be abnormal.
Critical Factors in the Chromatographic Measurement of Glycohemoglobin (HbA1)
Authors: Simon M , Eissler J
Published: September 2013

Measurement of glycohemoglobin has been proposed as a criterion for the management of diabetes mellitus. We evaluated various conditions critical to the accuracy and precision of the cation-exchange method.

Tolerance limits for each variable were defined as follows: phosphate-eluding buffer (0.06 ± 0.005 mol/L ph 6.70−6.72), column temperature (19−21°C), and resin equilibration (to phosphate buffer, 0.07 mol/L, pH 6.70 ± 0.01). Hemoglobin absorbance measured in the Sorét region (approximately 416 nm) of the first chromatographic fraction divided by that of the total hemolysate provided the most accurate and precise result. Overall between-run precision expressed as coefficient of variation (CV, in percent) of normal and diabetic pools was 4.8% and 5.1%, respectively. When purified HbA1c was added to hemolysates, recovery was 90–95%. Results were linear to at least 18% glycohemoglobin. Hemoglobin F (HbF) interfered with the method, whereas HbC and HbS did not. Red cells could be stored frozen for at least 6 days, thus easing transport of outpatient samples. A reference range of 6.0−8.8% glycohemoglobin was established from 85 nondiabetic adults (ages 23–65 yr). In a clinical study, only 4 of 13 treated diabetic patients believed to be in good control showed glycohemoglobin results within the normal range. All of the 19 treated diabetics in fair or poor control showed glycohemoglobin results greater than 10% of total Hb, ie., well above the normal range.
Monolayer Cultures of Adult Pancreatic Islet Cells on Osmotically Disrupted Fibroblasts
Authors: Meda P , Hooghe-Peters E L , Orci L
Published: September 2013

A simple method that permits the attachment of fully dissociated adult pancreatic islet cells to culture dishes, using osmotically disrupted fibroblasts, is described. Using this system, monolayer cultures consisting of either isolated or clustered adult endocrine islet cells can be readily established in standard culture media.
Nonenzymatic Glucosylation of Serum Proteins and Hemoglobin: Response to Changes in Blood Glucose Levels in Diabetic Rats
Authors: Day James F , Ingebretsen Carmel G , Ingebretsen William R , Baynes John W , Thorpe Suzanne R
Published: September 2013

The relationship between concentrations of blood glucose and nonenzymatically glucosylated serum proteins was studied in rats with alloxan-induced diabetes of varying severity. Fasting serum glucose correlated strongly with both glucosylated albumin (r = 0.91, P < 0.001) and glucosylated serum protein (r = 0.93, P < 0.001). The relative rates of response of serum protein and hemoglobin glycosylation to changes in blood glucose were also compared. Following withdrawal of insulin from diabetic rats, the half-times to reach new steady state levels of blood glucose, glucosylated serum proteins, and glycohe-moglobins were about 2, 3, and 8 days, respectively. Similarly, on reinstitution of insulin therapy, the half-times for these same indices to return to baseline values were 2, 3.5, and 15 days, respectively. Changes in glucosylated albumin were more sensitive than glycohemoglobins to changes in serum glucose, consistent with the observation that albumin was glucosylated at about 10 times the rate for hemoglobin in incubations in vitro. These data indicate that glucosylated serum protein measurements can serve as a sensitive, short-term integrator of blood glucose homeostasiS in diabetes.