bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional and Morphologic Characterization of Human Insulinomas
Authors: Berger Michael , Bordi Cesare , Cüppers Hans-J , Berchtold Peter , Gries F Arnold , Münterfering Horst , Sailer Rudolf , Zimmermann Horst , Orci Lelio
Published: September 2013

Circulating levels of insulin, proinsulin-like component, glucagon, growth hormone, and pancreatic polypeptide were measured in 12 patients with functioning insulinomas, and the suppressibility of serum insulin by somatostatin and diazoxide was assessed before surgical removal of the tumors. The hormone content of the tumors was evaluated by radioimmunoassay and by immunofluorescence and the structure of the tumor cells by electron microscopy. Based on these findings, we propose a new classification of insulinomas in two groups: group A is characterized morphologically by abundant well-granulated typical B-cells, trabecular arrangement of tumor cells, and uniform insulin immumofluorescence; functionally, these tumors are associated with a moderate elevation of proinsulin-like component and with an almost complete suppressibility of serum insulin by somatostatin and diazoxide. In contrast, tumors of group B are characterized by scarce well-granulated typical B-cells, a medullary-type histologie structure, and irregular insulin immunofluorescence; functionally these tumors show elevated circulating levels of proinsulin-like component and a marked resistance of insulin secretion to somatostatin and diazoxide inhibition. This way of separating human insulinomas in groups A and B represents a simplification of existing classifications and emphasizes the quantitative ultrastructure in relationship to suppressibility of insulin secretion. The proposed classification of human insulinomas in groups A and B, however, does not allow the assessment of the clinical or histopathologic malignancy of the tumors.
Influence of Polyethylene Glycol Insulin on Lipid Tissues of Experimental Animals
Authors: Neubauer H Paul , Obermeier Rainer , Schöne Hans-Hermann
Published: September 2013

Earlier investigations have revealed that polyethylene glycol-B1-insulin (PEG insulin) causes lower utilization of glucose in fat cells than does the unaltered hormone, even though the blood glucose-lowering activity of both preparations in intact animals is identical.

The present study was aimed to establish whether or not PEG insulin in regard to adipose tissues of intact animals has similar functions. Radioactive glucose was used to examine the influence of both native pork insulin and its PEG derivative on the incorporation of tracers into lipids. Male Wistar rats and male domestic rabbits received 14C- and/or 3H-labeled glucose intravenously, while the insulin preparations were administered by either the subcutaneous (s.c.) or the intravenous (i.v.) route. Under the influence of PEG insulin, diminished incorporation of 14C and/or 3H into adipose tissues was observed in all cases, yet both natural insulin and the derivative lowered the blood glucose to the same extent.

These observations allow the assumption that, by using certain modified insulins, it may also be possible to manipulate the extent of glucose metabolism by lipid tissues in diabetic patients.
Influence of Aging on Insulin Receptor Binding and Metabolic Effects of Insulin on Human Adipose Tissue
Authors: Bounder Jan , Östman Jan , Arner Peter
Published: September 2013

The influence of aging on the peripheral action of insulin was studied using subcutaneous adipose tissue from eight young (range 22–30 yr) and seven middle-aged (40–59 yr). healthy, normal-weight subjects. Insulin binding per cell was 50% lower in the older than in the younger group (P < 0.01), essentially owing to a decrease in the insulin receptor number. Concomitantly, insulin sensitivity, as reflected in the degree of antilipolysis and stimulation of glucose oxidation, was 10–20 times smaller in the older subjects (P < 0.01). Basal lipolysis and the maximum antilipolytic effect of insulin were similar in the two groups. The basal rate of glucose oxidation in the older subjects was less than one-half that for the younger group (P < 0.025), and the maximum level of insulin-induced glucose oxidation was lower by about 75% (P < 0.01). Age was significantly and negatively correlated with insulin receptor number (r = −0.81), basal production of 14Co2 (r = −0.73) and maximum level of insulin-induced glucose oxidation (r = −0.68). The decreases in the receptor number and insulin sensitivity were larger in early adulthood than in the elderly, while the decrease in insulin responsiveness was more uniform. It is concluded that aging is accompanied by impairment of the action of insulin on target cells, owing to alterations at both the receptor and the postreceptor levels. These mechanisms, and especially the postreceptor defect, may be essential factors in the development of relative glucose intolerance in the aged.
Photocoagulation for Diabetic Maculopathy: A Randomized Controlled Clinical, Trial Using the Xenon Arc
Authors:   British Multicentre Study Group
Published: September 2013

The final results of a randomized controlled clinical trial of photocoagulation for diabetic maculopathy are reported, when all patients have been followed for at least 5 yr and some for as long as 7 yr. Ninety-nine patients with two similarly affected eyes had one eye chosen by a random procedure, treated with the xenon-arc photocoagulator; the untreated eyes remained as control.

The mean visual acuity deteriorated by less than one line in treated eyes but by more than 2 lines in the controls (P < 0.01). The difference in deterioration was greatest in patients whose initial vision was 6/6-6/9, and was not significant in those whose visual acuity was 6/36 or worse. Thirteen patients became blind in both eyes (visual acuity of 6/60 or less for 2 consecutive yearly assessments), 6 in the treated eye only, and 26 in the control eye only (P < 0.01). Again the divergence between treated and control eyes was most marked in those whose initial vision was 6/6–6/9, (only one treated but 10 control eyes became blind). Hard exudates, microaneurysms, and hemorrhages improved more in the treated eyes (0.05 < P < 0.001) and more control eyes developed new vessels during the follow-up period.

Twenty-three patients died during follow-up and another 16 failed to complete the study. Though the blood pressure of those who died was higher than those who survived (P < 0.05 for both systolic and diastolic) no other medical abnormalities at entry had any clear effect on visual outcome or 5-yr survival.

It is concluded that photocoagulation is of benefit in maintaining vision in diabetic maculopathy if the disease is not too far advanced.
The Effects of Ingested and Intravenous Glucose on Forearm Uptake of Glucose and Glucogenic Substrate in Normal Man
Authors: Radziuk J , Inculet R
Published: September 2013

The forearm uptake of glucose, lactate, and alanine was determined in overnight fasted man following both oral glucose loading and the intravenous (i.v.) infusion of glucose in an absorption pattern. Arterial glucose concentrations were lower following oral than following i.v. loading and forearm glucose uptake was 50% higher after oral glucose. Arterial insulin levels were higher in the first 2 h during oral loading. Forearm lactate and pyruvate production did not change significantly during glucose administration by either route so that the increased plasma levels are due to splanchnic production.
Insulin Receptor Binding to Monocytes, Insulin Secretion, and Glucose Tolerance Following Metformin Treatment: Results of a Double-Blind Cross-Over Study in Type II Diabetics
Authors: Prager R , Schernthaner G
Published: September 2013

We studied the effect of metformin therapy (1700 mg daily) on glucose tolerance, insulin secretion, and insulin binding to monocytes in 10 non-insulin-dependent diabetics (mean duration of disease 2.6 yr) who were treated for 4 wk with either metformin or placebo in a double-blind cross-over study.

Metformin induced a significant decrease of glucose levels during an oral glucose load compared with placebo treatment (P < 0.001). All patients studied showed normal or elevated basal insulin and C-peptide levels; their responses to an oral glucose load, however, were relatively hypoinsulinemic without any significant difference between metformin and placebo. Insulin binding to monocytes was nearly identical at ail insulin concentrations tested in the placebo or metformin therapy phase.

These data indicate that the glucose-lowering potency of metformin in non-insulin-dependent diabetics cannot be associated with changes in receptor number or affinity. It is suggested that metformin might have a positive influence on postreceptor defects in non-insulin-dependent diabetics.
The Adrenergic β-Receptor Adenylate Cyclase System in Heart and Lymphocytes from Streptozotocin-Diabetic Rats: In Vivo and In Vitro Evidence for a Desensitized Myocardial β-Receptor
Authors: Gøtzsche Ole
Published: September 2013

The myocardial β-receptor adenylate cyclase system was investigated in short-term streptozotocin-diabetic rats. Earlier reports of a decreased sensitivity of the myocardium to isoproterenol (ISO) in these animals were elucidated by measuring the in vivo production of cAMP after ISO. A substantial decrease was seen in diabetic animals compared with controls and starved animals, and thyroxine treatment, known to sensitize the myocardium to catecholamines, did not normalize the response. The desensitization was retained in a membrane fraction in such a way that ISO was unable to increase the cAMP production while stimulation via the nucleotide-binding protein (with NaF or GTP) leads to a normal cAMP response. As the β-adrenergic receptor number and affinity turned out to be identical in control and diabetic animals, a functional uncoupling of the myocardial β-receptor from productive adenylate cyclase activation seems thus to exist in experimental diabetes. It is unlikely that it has anything to do with the thyroid status of the animals, but the possibility of a catecholamine-induced desensitization cannot be excluded. The phenomenon is not universal as the β-receptor-adenylate cyclase system is normal in isolated spleen lymphocytes. Whether the described phenomenon obtained in an animal study has any relevance for the increased incidence of heart failure in human diabetes mellitus is not known at present.
Suppressible Glucagon Secretion in Young, Ketosis-Resistant, Type “J” Diabetic Patients in India
Authors: Rao R Harsha , Vigg B L , Rao K S Jaya
Published: September 2013

Plasma glucagon levels were measured in young individuals with severe, insulin-dependent, juvenile-onset diabetes mellitus to study whether differences in glucagon secretion were related to ketosis proneness and resistance. Fasting glucagon levels were similarly elevated in both classical, ketosis-prone, type I diabetic subjects and ketosis-resistant, type “J” subjects [70 ± 7 pmol/L (mean ± SEM) and 81 ± 10 pmol/L, respectively] compared with nonobese, nondiabetic controls (36 ± 3 pmol/L, P < 0.01). After oral glucose administration, however, glucagon responses were strikingly dissimilar in the two groups. In type I diabetic individuals, glucagon rose paradoxically during OGTT, by 21 ±4 pmol/L, an increase of 33 ± 10%; on the other hand, glucagon levels in type“J”diabetic individuals fell by 28 ± 7 pmol/L, a decrease of 33 ± 5%. There was no measurable increase in plasma free insulin during OGTT in either group. Postprandial glucagon suppressibility may be relevant to the ketosis resistance that is characteristic of type “J” diabetes.
Glucosylated Collagen Is Antigenic
Authors: Bassiouny A R , Rosenberg H , McDonald T L
Published: September 2013

Sera from rats inoculated with in vitro glucosylated rat skin acid-soluble collagen were evaluated for specific antibody response using the enzyme-linked immunosorbent assay. The data indicate that the altered protein is capable of eliciting the production of antibodies, but unmodified collagen is not. The specificity of the generated antibodies appears to be directed toward the glucitollysine residues of the modified collagen. Sera from streptozotocin-induced diabetic rats contain antibodies that clearly bind glucosylated collagen.

These results provide support for the hypothesis that in diabetes mellitus increased collagen glucosylation during chronic hyperglycemia may be the initiating event of an autoimmune response leading to the long-term complications.
Successful Intracerebral Allotransplantation of Purified Pancreatic Endocrine Cells in Diabetic Rat
Authors: Tze Wah Jun , Tai Joseph
Published: September 2013

Single pancreatic endocrine ceils (PEC) have been demonstrated to restore normoglycemia when transplanted intracerebrally in diabetic rat recipients across a major histocompatibility barrier without immuno-suppression. Twelve out of twelve transplants of purified PEC have achieved long-term survival of over 176 days. This approach would provide a model to identify the specific cell(s) as inducer of graft rejection and an opportunity for transplantation study in spontaneous diabetic BB rats and larger diabetic animal models.
Sertoli Cell Function in Diabetic, Insulin-treated Diabetic, and Semi-Starved Rats
Authors: Hutson James C , Stocco Daugals M , Campbell G T , Wagoner J
Published: September 2013

It is well documented that long-term diabetes mellitus results in numerous deleterious consequences. However, considerable controversy exists concerning male reproductive function in diabetes. The purpose of this investigation was to study several endocrine parameters in diabetic male rats with emphasis on Sertoll cell function. Male Wistar rats were injected with streptozotocin and then either left untreated for 30 days or injected with insulin so as to prevent spillover of glucose into the urine. These two groups were compared with control animals that had only been injected with the vehicle for streptozotocin. Semi-starved control animals were included to determine if any of the potential endocrine alterations were related to body weight changes which occur in streptozotocin-injected rats. It was found that FSH, LH, PRL, and GH serum levels were reduced in diabetic animals. Only FSH was restored to normal by insulin injections. The testis, seminal vesicle, and epididymis weights were all reduced in diabetic animals. Insulin injections raised all organ weights; however, only testis weights were fully restored. Levels of epididymal ABP activity were found to be higher in diabetic animals when expressed per mg protein. Similar patterns of organ weight loss and hormonal alterations were observed in semi-starved rats. However, epididymal levels of ABP activity were unaffected by the semi-starved condition. While weight loss should be taken into consideration when interpreting cause and effect relationships in streptozotocin-treated animals, epididymal ABP levels appear to be well correlated with the altered metabolic state characteristic of diabetes.
Monoamine Oxidase Activity in Diabetes
Authors: Billett Ellen , Hanley Simon , Heptinstall Stanley , Mayer R John
Published: September 2013

Monoamine oxidase (MAO) activities were measured in platelets from insulin-dependent and non-insulin-dependent diabetic subjects and in platelets from nondiabetic controls. Circulating levels of glycosylated hemoglobin (HbA1) were determined simultaneously. Mean MAO activities were not significantly different in any of these groups. MAO activity did not relate to the age of the individual, but mean values for females were higher than mean values for males in healthy controls and in insulin-dependent diabetics. In this study mean HbA1 levels were higher in female than in male diabetics. There was no relationship between MAO activity and HbA1, level when results for males and females were analyzed separately.
Nerve Function and Metabolic Control in Teenage Diabetics
Authors: Young R J , Ewing D J , Clarke B F
Published: September 2013

Peripheral somatic and autonomic nerve function have been studied in 79 teenage (16–19 yr) diabetics and 20 age- and sex-matched normal controls. Almost three-quarters of the diabetics (72%) had abnormal peripheral somatic nerve function tests, and one-third (31%) had abnormal cardiac parasympathetic tests. Both motor and sensory peripheral somatic nerve abnormalities were related to poor prevalling glycemic control (HbA1) and duration of diabetes. Thus, the 27 patients with three or more (maximum six) peripheral nerve abnormalities had significantly higher HbA1 levels (P < 0.001) and longer duration of diabetes (P < 0.01) than the 22 with no abnormalities. Individual peripheral somatic nerve tests almost invariably correlated only with HbA1 (median motor, P < 0.05; peroneal motor, P < 0.001; sural sensory, P < 0.001) or duration of diabetes (median sensory, P < 0.001). Sensory potential amplitude, as well as conduction velocity, was frequently reduced, implying axonal involvement. These findings suggest that abnormal peripheral and autonomic nerve function are common in young insulin-dependent diabetics and that poor metabolic control is a major determinant of the damage.
HLA Genotypic Study of Insulin-dependent Diabetes: The Excess of DR3/DR4 Heterozygotes Allows Rejection of the Recessive Hypothesis
Authors: Rotter Jerome I , Anderson Carol E , Rubin Rachel , Congleton Jane E , Terasaki Paul I , Rimoin David L
Published: September 2013

The genetics of insulin-dependent diabetes mellitus (IDDM) is currently an area of controversy, with some investigators proposing heterogeneity within the HLA region and even the existence of non-HLA-linked susceptibility genes, and others maintaining that a simple autosomal recessive gene linked to HLA with reduced penetrance is an adequate explanation. To resolve this latter question, we report here a simple method of testing whether a single HLA-linked susceptibility gene is inherited in a recessive fashion when it is associated with two different HLA alleles, as is the case for IDDM. It is shown that if the number of DR3/DR4 heterozygotes in a diabetic population exceeds the combined sum of DR3/3 and DR4/4 homozygotes in that same diabetic population, then a recessive mode of inheritance can be rejected. The advantages of the method are that it does not depend on ratios, as do relative risk calculations, nor does it depend on control data, but is based only on studies of the diabetics themselves. With data on 193 genotyped IDDM patients, we can clearly reject the recessive mode of inheritance, since the number of heterozygotes is 68 compared with a maximum of 22 homozygotes (P < 10−4). Eight other published studies are in concordance with these results. Therefore, a nonparametric test, independent of the significance of any individual study, rejects equality of heterozygotes and homozygotes (P < 0.002) and rejects the simple recessive mode of inheritance as a direct consequence. We conclude that more complex modes of inheritance of HLA-linked IDDM susceptibility, such as two different diabetogenic alleles or multiple loci, must be entertained.
Polyantigenic Expansion of Basement Membrane Constituents in Diabetic Nephropathy
Authors: Falk Ronald J , Scheinman Jon I , Mauer S Michael , Michael Alfred F
Published: September 2013

The immunohistopathology of the intrinsic basement membrane-associated antigens were examined in diabetic nephropathy. In early and moderate stages of disease there was polyantigenic expansion of all the intrinsic components of mesangium, glomerular basement membrane (GBM), and tubular basement membrane (TBM) assessed by polyclonal antisera to collagen types IV and V, laminin, and by monoclonal antibodies to type IV collagen and fibronectin and to four other intrinsic components of normal renal extracellular matrices (MBM10, 11, 12, and 15). In the mesangium the first intrinsic antigens to increase were fibronectin and type V collagen. In late stages of disease, there was a diminution in the mesangium of all of these antigens with the exception of type V collagen, which persisted. Additionally, antigens appeared in the mesangium, recognized by MBM11 and MBM15, which are normally present in fetal but not adult mesangial regions. Similarly, in the GBM in late stages of disease, there was a decrease in all of the antigens, except for a persistence of the antigen recognized by MBM15. However, in TBM all of the antigens assessed increased in early, moderate, and severe disease. These studies document the complexity of polyantigenic alterations in the development of diabetic nephropathy.
Diabetic Nephropathy: A Perspective
Authors: Mauer S Michael , Steffes Michael W , Goetz Frederick C , Sutherland David E R , Brown David M
Published: September 2013

The earliest manifestations of clinical diabetic nephropathy, including proteinuria, hypertension, and declining GFR, represent very advanced diabetic glomerulopathy with especially prominent mesangial expansion. Mesangial expansion, by restricting glomerular capillary filtration surface and lumenal volume, stimulates compensatory mechanisms analogous to those resulting from a marked reduction in nephron number. These compensatory mechanisms involve alterations in glomerular hemodynamics designed to maintain glomerular filtration but which ultimately injure the kidney. These hemodynamic perturbations are not specific to diabetes but represent a final common pathway toward endstage renal failure that also characterizes the remnant kidney. This thesis concludes that the onset of clinical diabetic nephropathy augurs inevitable decline in kidney function, and that only studies and interventions exercised before clinical nephropathy develops can influence understanding and outcome of diabetic nephropathy.
The Effect of Diabetes on Blood Flow Properties
Authors: McMillan Donald E
Published: September 2013

Blood flow is a complex process combining fluid shearing in both plasma and the interior of red blood cells with elastic deformation of blood's solid elements. The red cell membrane is the major solid in blood, but platelets and white cells contribute solid behavior as well. Changes in blood's flow properties are often hidden by blood's ability to change its pattern of response. Capillary viscometry can be used to examine serum, plasma, and hemoglobin solutions directly, but rotational viscometry, where regularity of fluid shearing can be controlled to a narrow shear rate range, is required to study blood flow effectively. The most striking diabetic blood flow abnormality is best seen in time-based rotational viscometer studies that demonstrate the pattern of development of shear stress as flow becomes established. In such studies blood demonstrates both viscoelastic and thixotropic behavior; in diabetes blood's thixotropy is substantially increased. The diabetic pattern appears to be produced by a combination of reduced erythrocyte deformability and increased erythrocyte aggregation due to plasma protein changes. The plasma protein changes observed in diabetes are linked to the development of glucose intolerance but they are not specific to diabetes. The combined increase in aggregation and resistance to deformation of red blood cells produces blood flow abnormalities that can be detected primarily at low shear rate. Plasma protein changes and alteration in blood viscosity are absent from children with diabetes, while such changes tend to be associated with diabetic microangiopathy in adults. In some in vivo conditions, the effects on blood flow that can be linked to erythrocyte deformability are magnified out of proportion to measurements made in vitro. Vessel wall injury may be produced by the adult diabetic hemorheologic changes, contributing to the development of both diabetic microangiopathy and atherosclerosis.
Potentiation of Insulin Action by a Sulfonylurea in Primary Cultures of Hepatocytes from Normal and Diabetic Rats
Authors: Salhanick Arthur I , Konowitz Paul , Amatruda John M
Published: September 2013

Although sulfonylureas have been used extensively in the treatment of non-insulin-dependent (type II) diabetes, controversy exists as to whether these agents act primarily by increasing insulin secretion or by enhancing insulin action. To determine whether sulfonylureas potentiate insulin action in the liver, we evaluated the ability of the sulfonylurea tolazamide to affect insulinsensitive lipogenesis utilizing primary cultures of hepatocytes prepared from both normal and nonketotic streptozotocin-diabetic rats. Hepatocytes were cultured for 16 h in serum-free media with no additions, tolazamide alone (0.3 mg/ml), or insulin (10−10 to 10−7 M) in the absence and presence of tolazamide. Following culture, lipogenesis and specific insulin binding were assessed. Dose-dependent increases in lipogenesis were found in hepatocytes from both normal and diabetic rats after the chronic exposure to insulin. In hepatocytes from diabetic rats, the basal and the maximal insulin-stimulated rates of lipogenesis were only 27% and 13% of normal, respectively, establishing this as a model of hepatic insulin resistance. In the presence of tolazamide, significant potentiation of insulin action was found in hepatocytes from normal and diabetic rats although hepatocytes from diabetic animals remained relatively resistant to insulin when compared with those from nondiabetic animals. While exposure to tolazamide increased insulin responsiveness in both groups of cells, no changes in insulin sensitivity (ED50) were observed. Tolazamide significantly increased insulin binding (12%) in hepatocytes from normal rats cultured in the absence of insulin, but no alterations in insulin binding were found under incubation conditions in which tolazamide potentiated insulin action. These results give the first direct evidence for an insulin-dependent action of a sulfonylurea on the liver from both normal and diabetic rats and indicate that the enhancement of insulin responsiveness occurs through postbinding mechanisms.
Intratesticular Transplants of Islet Xenografts (Rat to Mouse)
Authors: Bobzien Bonnie , Yasunami Yohichi , Majercik Mary , Lacy Paul E , Davie Joseph M
Published: September 2013

Freshly isolated rat islets were transplanted into the testis of diabetic mice. The intratesticular islet xenografts produced normoglycemia in the diabetic recipients. The survival time of the intratesticular xenografts was significantly longer than intrasplenic, intrahepatic, and renal subcapsular sites of transplantation of xenografts of freshly isolated rat islets. Three of the recipients with intratesticular islet grafts were still normoglycemic at 60 days after transplantation, and orchidectomy resulted in a return to the diabetic state. The findings indicate that the testis provided a more privileged immunologic site than either the spleen, liver, or kidney and the lower temperature of the testis apparently did not affect the function of the islet grafts since the recipients became normoglycemic.
Hypothesis: PGE, Carbohydrate Homeostasis, and Insulin Secretion: A Suggested Resolution of the Controversy
Authors: Robertson R Paul
Published: September 2013

Published information derived from studies of prostaglandins on carbohydrate homeostasis and insulin secretion has been considered somewhat controversial by many investigators. An analysis of the literature published since 1876 suggests that this controversy has its roots in imprecise terminology and overgeneralization of data rather than irreconcilable scientific experiments. The two major sources of confusion have been failure to distinguish glucose-induced acute insulin responses from insulin secretion in general and failure to appreciate that the behavior of indomethacin is not consistent with the effects of other nonsteroidal antiinflammatory drugs (cyclooxygenase inhibitors) on glucose homeostasis and insulin secretion. When acute insulin responses to glucose specifically are examined and data from indomethacin studies are excluded, the available information consistently indicates that prostaglandin E has adverse effects on glucose homeostasis and insulin secretion.
Immunologic Aspects of the Nonobese Diabetic (NOD) Mouse: Abnormalities of Cellular Immunity
Authors: Kataoka Shigeki , Satoh Jo , Fujiya Hiroshi , Toyota Takayoshi , Suzuki Ryuji , Itoh Kyogo , Kumagai Katsuo
Published: September 2013

Experiments were performed on 12-wk-old nonobese diabetic (NOD) mice to investigate the immunologic background of the condition, using ICR mice as controls. The results indicate the following: (1) absolute decreases in number of T lymphocytes, (2) depression of natural killer activity, (3) normal responsiveness in delayed type hypersensitivity and functional depression of killer T cells against allogeneic tumors, (4) diminished resistance to herpes virus infection, and (5) enhanced production of polyclonal antibodies to T cell-dependent antigens. These features are similar to those noted in other autoimmune diseases of man and in their experimental models in laboratory animals. Elucidation of the pathogenetic mechanism of autoimmune diabetes mellitus in NOD mice, therefore, may contribute to the diagnosis, treatment, and prevention of a wide variety of autoimmune diseases.
Elevated Proinsulin Biosynthesis In Vitro from a Rat Model of Non-insulin-dependent Diabetes Mellitus
Authors: Halban Philippe A , Bonner-Weir Susan , Weir Gordon C
Published: September 2013

Rats were injected with streptozotocin at 2 days of age. After 10–14 wk, the injected rats showed normal body weight with only modestly elevated fed plasma glucose (controls: 118 mg/dl, diabetic rats: 209 mg/dl). No significant difference between control and diabetic rats was found for overnight fasting plasma insulin levels. The diabetic rats had a retarded rate of disposal of intravenously injected glucose, with only 13% of the incremental increase in plasma insulin seen in control rats 2 min after glucose injection.

The immunoreactive insulin content of islets isolated from the diabetic rats was 14% of controls. However, these islets had 74% of the B-cell composition of controls, as estimated by quantitative morphometry. Insulin release (30 min) was lower from islets from diabetic rats than from controls, but was not lowered to the same extent as islet insulin content. Proinsulin biosynthesis was estimated by measuring the incorporation of [3H] leucine or of [3H] phenylalanine into immunoprecipitable material. Proinsulin biosynthesis was strikingly elevated in islets from diabetic rats. Although incorporation of labeled amino acids into total islet protein was also elevated for islets from diabetic rats, the elevation was less pronounced than for incorporation into immunoprecipitable material.

The diabetic state of these animals is thus associated with glucose intolerance in vivo, and an increased rate of insulin turnover in isolated islets studied in vitro.
A Quantitative Immunofluorescent Study of the Endocrine Cell Populations in the Developing Human Pancreas
Authors: Stefan Y , Grasso S , Perrelet A , Orci L
Published: September 2013

The immunofluorescent cell content of the pancreas of 8–40-wk fetuses and of 1.5–5-mo Caucasian infants was quantitatively evaluated using anti-insulin, anti-glicentin, anti-glucagon, anti-somatostatin, and anti-pancreatic polypeptide antisera. The most significant findings are: (1) the pancreas of 8–10 wk fetuses contains a sizable population of endocrine cells reacting exclusively to anti-glicentin antiserum. This cell population decreases and disappears in later stages and is replaced by the adult type glucagon/glicentin immunoreactive cell; (2) the pancreatic polypeptide-rich region shows a lower relative endocrine cell content as compared with the glucagon-rich region and its islets appear smaller; (3) in the total pancreas, the relative (volume density) and absolute (μl) insulin cell content increases regularly with age, while the relative volume of glucagon cells peaks in fetal life (wk 17–20) to decrease in infants, although remaining at higher levels than in adults; the relative and absolute volumes of somatostatin cells are elevated in fetal and infant stages studied where they represent the second most abundant cell type, while pancreatic polypeptide cells appear to least abundant cells during prenatal and infant life. These data show several differences with the pattern of the respective endocrine cell populations in the adult pancreas.
The Pharmacokinetics of Insulin After Continuous Subcutaneous Infusion or Bolus Subcutaneous Injection in Diabetic Patients
Authors: Kobayashi Tetsuro , Sawano Shinji , Itoh Tokuji , Kosaka Kinori , Hirayama Hiroki , Kasuya Yasuji
Published: September 2013

Pharmacokinetic models of insulin were examined in order to describe a plasma concentration-time profile after subcutaneous (s.c.) administration of insulin to the patients with insulin-dependent diabetes mellitus (IDDM) or non-insulin-dependent diabetes mellitus (NIDDM). Diabetic subjects were restricted to those with fasting plasma insulin levels around the lowest limit for insulin assay (5 μU/ml). A one-compartment open model with first-order absorption and elimination was appropriate for estimating the plasma concentration-time profile of insulin injected or infused subcutaneously. In the case of continuous s.c. insulin infusion (CSII) for 1 h at the rate of 3 ml/h (2–3 U/ml), the absorption rate constant (Ka), elimination rate constant (Ke), and distribution volume (Vd) were 0.026 ± 0.001 min−1 (mean ± SEM; absorption half-life: 27 min), 0.013 ± 0.005 min−1 (elimination half-life: 53 min), and 1.99 ± 0.49 L/kg body wt, respectively. These values did not differ significantly from those generated by single bolus s.c. injection of undiluted insulin (40 U/ml). The calculated areas under the plasma insulin concentration-time curves from time zero to infinity ([AUC]∞0) did not differ after each mode of administration, while the [AUC] ∞0 after CSII was about 32% of that following intravenous bolus injection (P < 0.01).

The following conclusions can be drawn from these results: (1) the plasma concentration-time profile of insulin after CSII or bolus s.c. injection can be analyzed by pharmacokinetic modeling, (2) the absorption kinetics of insulin did ot differ significantly between two modes of s.c. insulin administration in the patients with IDDM or NIDDM, and (3) the insulin after CSII or single bolus s.c. injection seems to be degraded at the s.c. site to the same extent.
The Effect of Cholesterol Feeding and Alterations in Bile Acid Homeostasis on De Novo Sterologenesis in Diabetic Rats
Authors: Feingold Kenneth R , Wiley Millie Hughes , Moser Arthur H , Lear Steven R
Published: September 2013

Previous studies have demonstrated that de novo cholesterol synthesis is increased two- to threefold in the intestines of diabetic animals. This increase is due to a stimulation of cholesterogenesis in both the small and large intestine but, quantitatively, the small intestine is primarily responsible for the observed increase. The present study examined the effect of cholesterol feeding and alterations of bile acid homeostasis on de novo sterol synthesis in intact normal and diabetic animals. Cholesterol feeding in the control animals did not affect sterol synthesis in the small intestine, but in diabetic animals cholesterol feeding markedly inhibited small intestinal sterologenesis. The threefold stimulation of small intestinal sterol synthesis observed in diabetic animals is completely obliterated by cholesterol ingestion. Moreover, this inhibition of sterol synthesis by cholesterol feeding in the small intestine of diabetic animals occurred very rapidly (within 36 h). In the large intestine, cholesterol feeding did not influence sterol synthesis in either the diabetic or control animals. In the liver, cholesterol feeding markedly inhibited sterol synthesis to similar degrees in the diabetics and controls. Colestipol feeding and biliary drainage, procedures that reduce bile acid pool size, stimulated sterol synthesis in the liver and small intestine of both diabetic and control animals. However, reductions in bile acid pool size increased sterologenesis in the large intestine in control animals but had no effect in the diabetics. Bile acid ingestion did not alter either small or large intestinal sterologenesis in the diabetic or control animals. In conclusion, the present study demonstrates the sterol synthesis is enhanced in the small and large intestine of diabetic animals and, moreover, both the cholesterol- and bile acid-mediated regulation of cholesterol synthesis in the intestines of the diabetic animals is altered from normal.
Changes in Blood Flow Close to Subcutaneous Insulin Injection Sites in Stable and Brittle Diabetics
Authors: Williams Gareth , Pickup John , Clark Adrian , Bowcock Sally , Cooke Ernest , Keen Harry
Published: September 2013

Photoelectric Plethysmography (PPG) Was Used to investigate blood flow changes closeto superficial subcutaneous injection sites. As a validation procedure, the PPG response to subcutaneous injection of a known hyperemic agent, prostaglandin E, (10−5 M), was shown to correlate strongly with subcutaneous blood flow changes estimated by the established technique of133Xe washout.

Changes in blood flow over the subcutaneous injection sites of insulin (Actrapid) and insulin diluent were measured by photoelectric plethysmography in six nondiabetics and in six stable and seven brittle insulin-dependent diabetics. In all subject groups, an acute increase in local blood flow was seen within 2 min of both insulin and diluent injections, probably caused by injection trauma. At diluent injection sites, this acute hyperemia faded rapidly, blood flow returning to preinjection levels within 15–20 min, and there was no further increase in blood flow in any of the subjects. Insulin injected into the nondiabetics and stable diabetics caused a pronounced increase in local blood flow, sustained for at least 60 min after injection. In the brittle diabetics, however, there was no prolonged local hyperemia, the response being significantly less than that seen in both the nondiabetics and the stable diabetics.

Insulin-related hyperemia close to injection (or infusion) sites may be important in subcutaneous insulin absorption. Its near-absence in brittle diabetics may contribute to the impaired response to subcutaneous insulin characteristic of these patients.
Early Detection of Degraded A14-125I-Insulin in Human Fibroblasts by the Use of High Performance Liquid Chromatography
Authors: Stentz F B , Harris H L , Kitabchi A E
Published: September 2013

We studied the metabolism of A14-125I-Insulin in intact human fibroblasts using high performance liquid chromatography (HPLC) to detect and separate its early degradation products. The high resolving power of HPLC enabled us to separate what has been considered “intact insulin” by Sephadex G-50 chromatography or TCA precipitability into two additional peaks that had decreased biochemical properties with respect to immunoprecipitability and receptor binding but not decreased TCA precipitability. We conclude that human fibroblast is capable of metabolizing insulin within 2 min at 37°C into intermediate molecules that can be detected by HPLC but not by TCA precipitability or molecular sieve chromatography.
Inhibition of Glucagon Secretion in the Human Newborn by Glucose Infusion
Authors: Grasso S , Fallucca F , Mazzone D , Giangrande L , Romeo M G , Reitano G
Published: September 2013

Plasma glucagon, serum insulin, and blood glucose responses during a 30-min glucose (1 g/kg body wt) or saline infusion were reported in 37 full-term and 35 preterm infants. They were studied either on the first day of life before feeding was initiated or during the first week of life.

Glucose infusion promptly suppressed glucagon secretion in all infants even from the initial hours of extrauterine life. The mean maximal decrement in percentage in the full-term infants on the day of birth and older was 54 ± 4% and 61 ± 6%, respectively, while the maximaldecrement in the preterm infants on day of birth and older was significantly lower (44 ± 3% and 38 ± 4%, respectively). The insulin response to glucose was variable in all infants and most of them showed a delayed rise of serum insulin.

No change in plasma glucagon, blood glucose, and serum insulin was observed during and after saline infusion.
Endogenous Prostaglandin Synthesis and Glucose-induced Insulin Secretion from the Adult Rat Pancreatic Islet
Authors: Evans Marilyn H , Pace Caroline S , Clements Rex S
Published: September 2013

Although exogenous prostaglandins are recognized modulators of insulin secretion, the relationship between their endogenous synthesis and insulin secretion has not been rigorously studied in isolated adult rat islets. Using 3H-arachidonic acid as a tracer, we evaluated the effect of glucose stimulation upon the incorporation of this fatty acid into islet phospholipids and prostaglandins (separated by extraction and sequential silicic acid, thin-layer and paper chromatography). We observed that 3H-arachidonic acid was incorporated into islet phospholipids and prostaglandins under basal conditions (0.3 mg/ml glucose). Furthermore, exposure of islets to a stimulatory glucose concentration led to significant increases in the recovery of 3H-arachidonic acid-derived radioactivity in islet phosphatidylethanolamine, phosphatidylserine, sphingomyelin, and phosphatidylinositol as well as into all of the measured prostaglandins (A2,B2, D2, E2, and F2α).

The most marked increases in recovered radioactivity resulting from a stimulatory glucose concentration were in islet phosphatidylethanolamine and prostaglandin A2 (which we believe to be derived, in large part, from endogenously synthesized prostaglandin E2). These glucose-induced increases in 3H-arachidonic acid-derived radioactivity in both the phospholipid and the prostaglandin fractions were eliminated by the inhibition of phospholipase A2 activity with mepacrine or by the inhibition of cyclooxygenase activity with sodium salicylate.

When islets prelabeled with 3H-arachidonic acid were exposed to a high glucose concentration in a perifusion system, there was a brisk extracellular release of radioactivity (presumably representing unidentified prostaglandins) that began within 1 min and that peaked slightly before the peak of the first phase of insulin secretion. Inhibition of either phospholipase A2 or of cyclooxygenase activity prevented the glucose-induced release of radioactivity and converted the pattern of insulin secretion from biphasic to monophasic. We conclude that the adult rat pancreatic islet rapidly incorporates arachidonic acid into phospholipids and prostaglandins and that this incorporation is markedly increased in the presence of a stimulatory glucose concentration. Studies with inhibitors of prostaglandin synthesis suggest that the endogenous synthesis of prostaglandins induced by glucose may contribute to the biphasic pattern of glucose-stimulated insulin secretion from the rat pancreatic islet.
Immunoreactivity of Human Insulin of Recombinant DNA Origin
Authors: Kumar Dinesh , Alexander Charles M , Zeidler Adina , Rhodes James J , Boarman Christopher C , Hoopes Michael T
Published: September 2013

To evaluate possible advantages of human insulin of recombinant DNA origin (HI) in the treatment of diabetic patients, we compared cellular and humoral immunoreactivities of HI and porcine insulin (PI).

Anti-insulin IgE bound equal amounts of 125I-HI and 125I-PI. There was no difference between HI- and PI-stimulated lymphocyte transformation indices.

The binding of 125I-HI with circulating anti-insulin IgG was lower compared with 125I-PI binding (12.1 ± 1% versus 15.4 ± 1.5%, P < 0.001) in 60 insulin-treated cases.

Thirteen sera were selected for high antibody titers and analyzed in detail. In the competitive inhibition assays, a 50% displacement of 125I-PI required a fourfold higher concentration of HI than PI. Although total insulin binding capacities were almost equal, 63 ± 11 nM/L for PI and 60 ± 12 nM/L for HI, the high-affinity antibodies had significantly reduced avidity for HI compared with PI. These differences in avidities suggest that HI may be useful in treatment of immune-type insulin resistance.
Effects of Species of Origin, Purification Levels, and Formulation on Insulin Immunogenicity
Authors: Fineberg S Edwin , Galloway John A , Fineberg Naomi S , Goldman Jose
Published: September 2013

The immunogenicity of purified pork insulins (PPI) with and without (groups 1 and 2,respectively) trace contamination of beef insulin was contrasted with mixed beef pork insulin of lower purity (MBP, group 3) in 137 patients who had not previously been treated with insulin. Patients and physicians were blinded with regard to the species source of insulin and studies were conductedfor a minimum of 1 yr. Antibody development to insulin was assessed by species-specific binding of 125I-insulin by acid charcoal extracted sera, as well as by measurement of insulin prebound to immunoglobulins by a polyethylene glycol precipitation method. NPH- and lente-treated individuals had equivalent antibody responses with regard to the rate of development of antibodies, and maximum immune responses to insulin. In all patient groups, antibody bound insulin as wellas species-specific binding of 125I-insulin increased significantly over time (all P < 0.01 for specific binding of pork and beef insulins SBP and SBB, as well as bound insulin). Maximum bound insulin and SBB as well as bound insulin and SBB over the entire course of the study were significantly greater in group 1 than in group 2 patients (both P < 0.05) The rate of development and magnitude of antibodies' responses in both PPI-treated groups were significantly less than that seen in the MBP group (all P < 0.01). New formation of antibeef proinsulin antibodies was seen in one patient from groups 1 and 3, but not in group 2. In all groups, insulin dose per day and fasting serum glucose concentrations increased by about 5 U/day and 10 mg/dl over 1 yr, but groups did not differ. MBP insulin used in these studies proved to be significantly less immunogenic than PPI alone.
Quantification of Insulin Secretion and In Vivo Insulin Action in Nonobese and Moderately Obese Individuals with Normal Glucose Tolerance
Authors: Reaven Gerald M , Moore Jorene , Greenfield Michael
Published: September 2013

Insulin secretion and in vivo insulin action were quantified in nonobese and moderately obese subjects (approximately 35% above desirable body weight) with normal glucose tolerance. Insulin secretion was estimated by determining plasma insulin responses to a 75-g oral challenge, and in vivo insulin-stimulated glucose uptake by the euglycemic clamp technique.

Plasma glucose levels of the two groups were identical during the glucose tolerance test, butthe plasma insulin response was significantly greater (P < 0.01) in the bese subjects. However, insulin-stimulated glucose utilization by the two groups was equal during the euglycemic clamp studies. These results were supported by the fact that degree of obesity correlated significantly with insulin response (r = 0.61, P < 0.005), but not with insulin-stimulated glucose utilization (r = −0.25, P > 0.2). Thus, indirect evidence that moderately obese subjects were more insulin-resistant based on measurement of plasma insulin responsewas not supported by direct quantification of insulin action. One explanation for these findings is that the height of the plasma insulin response bears no relationship to loss of in vivo insulin action, but that seems unlikely in view of the fact that there was a significant correlation (r = −0.52, P < 0.01) between these two variables in the group as a whole. Therefore, it appears that the hyperinsulinemia seen in obese individuals may not be a simple function of insulin resistance, and that the ability of insulin to stimulate glucose utilization is not significantly impaired in moderately obese subjects with normal glucose tolerance. Alternatively, the degree of impairment in insulin action seen in these individuals is insufficient to be detected by the euglycemic clamp technique.