bluuebunny/crossref_metadata_2025 huggingface dataset:
Elevated Portal and Peripheral Blood Concentration of Immunoreactive Somatostatin in Spontaneously Diabetic (BBL) Wistar Rats: Suppression With Insulin
Authors: Patel Yogesh C , Wheatley Thomas , Malaisse-Lagae Francine , Orci Lelio
Published: September 2013

Immunoreactive somatostatin (IRS) was measured in extracted plasma obtained from the hepatic portal vein (PV) and inferior vena cava (IVC) of acute, untreated, spontaneously diabetic Wistar rats (BBL), insulin-treated diabetic rats, and nondiabetic controls. Acetic acid extracts of the pancreas and entire gastrointestinal tract were assayed for IRS, and the volume density of pancreatic D-, A-, and B-cells was determined by quantitative morphometry. The concentration of IRS in the PV and IVC of the untreated diabetic rats was significantly elevated compared with controls, with a much greater percent increase in the IVC compared with the PV. Insulin treatment for 4–6 wk restored the elevated PV and IVC levels to control values. The pancreatic content of IRS and the volume density of D-cells was severely reduced in the diabetic groups whereas gut IRS was unchanged. These data suggest that the elevated blood levels are secondary to insulin deficiency and result from altered peripheral metabolism and/or increased secretion of IRS most probably from the gut. The increased peripheral blood concentration of IRS raises the possibility of an endocrine role of circulating somatostatin in diabetes. The reduction in pancreatic IRS found in this model is probably secondary to insulitis and contrasts with the D-cell augmentation reported in streptozotocin-dia-betic rats.
Perfect Normalization of Excessive Glucagon Responses to Intravenous Arginine in Human Diabetes Mellitus With the Artificial Beta-Cell
Authors: Kawamori Ryuzo , Shichiri Motoaki , Kikuchi Mikio , Yamasaki Yoshimitsu , Abe Hiroshi
Published: September 2013

To elucidate the precise significance of pancreatic A-cell hypersécrétion in the pathogenesis of diabetes mellitus, the change in the immunoreactive glucagon (IRG) response to intravenous arginine was studied in both nonobese, hypoinsulinemic non-insulin-dependent (NIDDM) and insulin-dependent diabetic (IDDM) subjects whose blood glucose responses and plasma immunoreactive insulin (IRI) simulated those of healthy subjects with the aid of the artificial beta-cell system that we originally developed.

In both five NIDDM and five IDDM subjects, blood glucose responses and plasma IRI after arginine challenges were made equivalent to those seen in healthy subjects by infusing insulin in response to blood glucose, revealing that previously exaggerated IRG responses were made completely similar to the responses in healthy subjects.

In summary, these results clearly demonstrate that the exaggerated response of A-cell secretion against arginine challenges in insulin-deficient diabetics is secondary to insulin lack, and the perfect normalization of its response is achieved only when both plasma insulin concentration and glycemie control simulate those of healthy subjects.
Tyrosine A14 [125I]monoiodoinsulin: Preparation, Biologic Properties, and Long-term Stability
Authors: Linde Susanne , Hansen Bruno , Sonne Ole , Holst Jens J , Gliemann Jørgen
Published: September 2013

125I-insulin was prepared by reacting 17.4 nmol porcine insulin (100 μg) with 5 mCi 125I (about 2.4 hmol) using the lactoperoxidase method. The reaction product was subjected to gel electrophoresis and the band containing A14 [125I]monoiodoinsulin was eluted. This preparation showed a specific activity of about 1.5 Ci/μmol as evaluated by radioimmunoassay and bioassay, i.e., about 75% of the theoretical maximum. The content of radioactive derivatives other than A14 monoiodoinsulin was less than 2%.

The binding affinity of tracer A14 monoiodoinsulin to adipocytes, hepatocytes, and cultured human lymphocytes was about twice as high as that of A19 monoiodoinsulin. Binding to antibodies was examined in 10 guinea pig anti-insulin sera. Three sera did not distinguish between the two tracers, whereas seven exhibited higher binding of the A14 tracer. A detailed analysis of one of the discriminating sera showed that the average affinity constant was about 2.5 times lower for the A19 tracer than for the A14 tracer.

The A14 monoiodoinsulin tracer is remarkably stable. After 200 days the specific activity had declined to about half of its original value which is consistent with the hypothesis that the physical decay of [125I]monoiodoinsulin (T12 = 60 days) extinguishes the activity of the molecule without causing major damage of other molecules. By this time 96% of the radioactivity migrated with insulin when subjected to gel filtration on Sephadex G-50, 4% was in the void volume, and nothing in the total column volume or later. Binding to receptors was indistinguishable from that obtained at time zero.

It is concluded that Tyr A14 [125I]monoiodoinsulin represents an advance in biologic work as compared with previous tracers for insulin.
A Familial Form of Obesity Without Hyperinsulinism at the Outset
Authors: Maruhama Yoshisuke , Abe Ryuzo
Published: September 2013

A total of 32 pairs of obese fathers or mothers and their obese offsprings, aged 20 yr or younger, from 25 families with established hyperinsulinemic obesity was studied. Although the obese pairs with offsprings aged 11-20 y r equally showed an insulin hyperresponse to glucose, the offsprings 10 yr or younger revealed a rather normal insulin response, despite the presence of obesity, and this contrasted with their fathers or mothers. No difference was found in the estimated age of onset between the two groups of offspring. The offsprings in both age groups ate a similar high carbohydrate, high calorie diet.

The results suggest that the insulin hypersecretion is not the primary trait in this form of familial obesity and that the insulin response to glucose becomes augmented during the maturation years of 11-20, thus resulting in the accumulation of hyperinsulinemic and hyperlipidemic adults in the family.
Lymphocytotoxic Antibodies and Histocompatibility Antigens in Juvenile-onset Diabetes Mellitus
Authors: Serjeantson S , Theophilus J , Zimmet P , Court J , Crossley J R , Elliott R B
Published: September 2013

Cold-reacting serum lymphocytotoxic antibodies (LCAs) were measured in sera from 230 insulin-dependent juvenile-onset diabetes mellitus (IDDM) patients and from 116 control subjects. LCAs were present in only 4% of control sera compared with 19% in IDDM patients. The most significant determinant of LCAs was time since onset of diabetes; within the first 12 mo, 55% of IDDM sera had LCAs, compared with 25% after one year and 15% after five years of diabetes. LCAs were absent in sera from patients with IDDM for 10 yr or more.

Genetic factors were also implicated in susceptibility to occurrence of LCAs. HLA antigen B8 and B18 were associated with an increased risk for LCAs, whereas HLA-B7 was associated with a decreased risk. The relative risk for LCAs in patients positive for HLA-B8 but not B7 was 2.3, compared with 0.0 in HLA-B7/B8 heterozygotes. In contrast, B7 did not provide protection from LCAs in B18/B7 IDDM patients.

Properdin factor B (Bf) alleles, which are in linkage disequilibrium with alleles of the HLA-B locus, were also associated with LCAs. IDDM patients with alleles BfS1 or BfF had a prevalence of LCAs of 7%, significantly less than the 39% in Bf-F1S or -F1 patients.

LCAs were not identical or closely correlated to pancreatic islet cell antibodies. Our findings indicate genetic heterogeneity in, yet, another autoimmune process in IDDM.
Islet Cells Grow after Transplantation of Fetal Pancreas and Control of Diabetes
Authors: Brown Josiah , Heininger Diane , Kuret Jeffrey , Mullen Yoko
Published: September 2013

The capacity of a fetal rat pancreas to grow and function was assessed after its transplantation into adult diabetic rats. One month after induction of diabetes by streptozotocin (SZ) (72.5 mg/kg) in adult Lewis rats, one syngeneic 17-17½ day fetal pancreas was transplanted under the kidney capsule. Insulin, initially 3 U/day and decreasing to 0.5 U every other day, was given for 27.5 ± 1.7 (× ± SEM) days (total dose, 48 ± 4 U) until the diabetes reversed (45 ± 3 days). Plasma glucose, 481 ± 10 mg/dl after SZ, fell after transplantation and cessation of insulin injections during a 4-mo period to 129 ± 2 mg/dl. Urine volume fell from 82 ± 4 ml per day to normal (12 ± 2), and glucose excretion, which was 7.7 ± 0.4 g per day after SZ, completely disappeared from the urine. The disappearance rate of glucose injected into the circulation, which was 0.50 ± 0.07% per minute in untreated diabetes, reverted to normal, 2.78 ± 0.18% per minute, not different from that in the normal control, 2.55 ± 0.13% per minute. Plasma insulin in control diabetic rats was totally unresponsive to glucose injection, despite a rise in plasma glucose concentration from 471 ± 5 mg/dl to 621 ±18 mg/dl. In transplanted rats, plasma insulin was moderately higher than normal before and at most time points after glucose injection. After removal of the transplanted pancreases, plasma glucose, urine volume, and glucose excretion returned to pretransplant levels and ketones appeared in the urine of all rats. Analysis of the insulin content of the pancreases removed 77 to 279 days after transplantation gave a value of 818 ± 43 mil, which is 22% of the insulin content of normal rats.

To achieve optimal growth and function of a transplanted fetal pancreas, careful control of the blood glucose is necessary during the period of growth and development.
The Effect of Prostacyclin and 6-Keto-Prostaglandin F1α on Insulin Secretion and Cyclic Adenosine 3′, 5′-Monophosphate Content in Isolated Rat Islets
Authors: Heaney Thomas P , Larkins Richard G
Published: September 2013

The effects of prostacyclin (PGI2) and its degradation product 6-keto-prostaglandin F1α (6-keto-PGF1α) on insulin secretion and cyclic adenosine 3′, 5′-monophosphate (cAMP) production were investigated in isolated rat islets. At a glucose concentration of 5.6 mM, addition of both PGI2 and 6-keto-PGF1α in a concentration range of 10−8–10−4 M significantly stimulated insulin secretion. The effects were concentration dependent, being maximal at an initial PGI2 concentration of 10−6M (2.7-fold increase, P < 0.001) and an initial 6-keto PGF1α concentration of 10−7 M (2.1-fold increase, P < 0.005). Lesser stimulation was observed at higher concentrations of both agents. In contrast to their relative effects on insulin secretion, PGI2 was approximately 100-fold more potent at increasing islet cAMP content.and higher concentrations were progressively more effective in raising islet cAMP content.

The effect of PGI2 on insulin secretion was dependent on the medium glucose concentration. At an initial PGI2 concentration of 40 μM, significant stimulation of insulin secretion was seen at glucose concentrations of 3.3 and 5.6 mM, but no effect was seen either in the absence of glucose, or at high glucose concentrations (10 and 16.7 mM). In contrast to the glucose dependency of the effect of PGI2 on insulin secretion, it caused a comparable increase in islet cAMP content at all glucose concentrations tested.

In the presence of 0.5 mM 3-isobutyl-1-methylxanthine (IBMX), PGI2 inhibited insulin secretion at glucose concentrations of 5.6–16.7 mM. However, in this situation PGI2 caused a further increase in islet cAMP above that found with IBMX alone. It is concluded that both PGI2 and 6-keto-PGF1α affect insulin secretion in vitro, although the effects of PGI2 may depend on its conversion to 6-keto-PGF1α. The effects of PGI2 can be either stimulatory or inhibitory, depending on the concentrations of glucose and IBMX in the medium, and cannot be explained solely by its effect on islet cyclic AMP content.
Enhanced Glucose Utilization During Prolonged Glucose Clamp Studies
Authors: Doberne Leonard , Greenfield Michael S , Schulz Bernd , Reaven Gerald M
Published: September 2013

Glucose clamp studies were performed to see if glucose utilization increased during extended periods of moderate hyperinsulinemia (80–100 μu/ml). Modifications of the standard euglycemic clamp were performed, and the amount of glucose metabolized (M) and the metabolic clearance rate (MCR) of glucose were calculated for each 10-min interval during the study. In seven subjects, the clamp was performed for 180 min, with the glucose infusion rate fixed from 120 to 180 min at the rate necessary to maintain basal plasma glucose concentration from 80 to 120 min. Under these conditions, mean plasma glucose concentration fell 18% during the last 60 min of the study, indicating increased glucose utilization. Twenty-four subjects, nonobese and obese normals and type II diabetics, had 3-h clamp studies performed. We documented an average increase of M by 21% and MCR by 28% in the third hour as compared with the second hour. Five-hour clamp studies in nine subjects and 8-h studies in two subjects indicated a continued rise in glucose MCR, until a plateau was reached at 4–6 h after initiation of hyperinsulinemia (mean = 88 μU/ml). This plateau was approximately 85% above the MCR of the last 30 min of a standard glucose clamp. Measurement of glucose turnover with 3H-3-glucose suggested that increasing suppression of hepatic glucose production was not responsible for the increases in glucose utilization noted. Insulin binding to erythrocytes was determined in 13 subjects before and after 180 min of hyperinsulinemia, and showed decreased total specific insulin binding. In a two-component high- and low-affinity model of insulin binding, the observed decrease in total insulin binding was primarily caused by a decrease in the high-affinity receptor component. These results suggested that glucose utilization continuously increased during a 5-h period of constant hyperinsulinemia, and this was due possibly to enhanced insulin sensitivity. This change took place in spite of a concomitant decrease in number of insulin receptors.
Production of 6-Oxo-Prostaglandin F1α by Rat Aorta: Influence of Diabetes, Insulin Treatment, and Caloric Deprivation
Authors: Rogers Susan P , Larkins Richard G
Published: September 2013

The production of 6-oxo-prostaglandin F1α (6-oxo-PGF1α), a stable metabolite of prostacyclin (PGI2), was examined in three separate series of experiments in aortae from rats with diabetes induced by streptozotocin (SZ) and aortae from nondiabetic control rats.

In the first series, it was shown that production of 6-oxo-PGF1α by aortae from rats with diabetes of 4–6-wk duration was significantly decreased compared with nondiabetic rats (0.77 ± 0.07 ng/mg wet weight aorta vs. 1.23 ± 0.11 ng/mg wet weight aorta, P < 0.001). Diabetic rats were treated with two doses of insulin, a lower dose of 8 U/kg/day that only partially corrected their plasma glucose and body weight compared with nondiabetic rats, and a higher dose of 25 U/kg/day that completely corrected their plasma glucose and body weight. Both insulin regimens completely reversed the defect in 6-oxo-PGF1α production.

In the second series, the time course of development of the defect in 6-oxo-PGF1α production was examined. It was found that two weeks after induction of diabetes, the aortic production of 6-oxo-PGF1α did not differ between control and diabetic rats. However, 4 and 7 wk after induction of diabetes, 6-oxo-PGF1α production was significantly reduced, even though the degree of hyperglycemia and hypoinsulinemia was the same as at 2 wk.

In the third series, the effect on aortic 6-oxo-PGF1α production of weight loss caused by restricted dietary intake was compared with the effect of a comparable weight loss caused by experimental diabetes. Again, the diabetic rats had significantly reduced 6-oxo-PGF1α production compared with control rats, but 6-oxo-PGF1α production in nondiabetic rats which had lost weight as a result of limited feeding was the same as nondiabetic control rats fed ad libitum.

It is concluded (1) that insulin treatment, even if insufficient to achieve perfect control of plasma glucose, can restore 6-oxo-PGF1α production to normal, (2) diabetes of greater than 2-wk duration is required to produce the abnormality, and (3) the reduced 6-oxo-PGF1α production is not a nonspecific consequence of weight loss.
Insulin Binding and Insulin Action in Fibroblasts from Patients with Maturity-onset Diabetes of the Young
Authors: Gelehrter Thomas , Dilworth Vickie , Valka Beth , McDonald Roderick , Schorry Elizabeth
Published: September 2013

To define cellular markers of the genetic heterogeneity underlying diabetes mellitus, we have examined insulin binding and insulin action in cultured skin fibroblasts from three diabetic and three unaffected individuals from a single family with a genetically defined subtype of non-insulin-dependent diabetes, maturity-onset diabetes of the young (MODY).1 Cells of two of the three MODY cell lines grew more slowly, were larger, and contained significantly more protein than did cells from their unaffected relatives. Binding of 125I-insulin was saturable and reversible, and halfmaximal displacement of tracer insulin occurred at 6 ng/ml (1 nM) unlabeled insulin in both normal and MODY cells. At physiologic concentrations of 125I-insulin (0.6 ng/ml), there was no difference in hormone binding between nondiabetic and diabetic cells when expressed as pg insulin bound per mg protein (26.0 ± 2.4 vs. 25.8 ± 2.1). When expressed as pg insulin bound per 106 cells, diabetic cells actually bound somewhat more insulin than nondiabetic cells. Insulin stimulated the transport of β-[14C]-methylaminoisobutyric acid (MeAlB) by increasing the Vmax for transport without changing the apparent Km. The insulin stimulation was half-maximal at 6 ng/ml and maximal at 100 ng/ml in both diabetic and control cells. Basal rates of transport of 0.1 mM MeAlB were the same in cells from patients and nondiabetic relatives (54 ± 7 vs. 53 ± 5 pmol · min−1 · mg protein−1); insulin stimulated a two-fold increase in transport in both. Dexamethasone (0.1 fiM) enhanced the insulin stimulation of MeAlB transport to the same extent in MODY (163 ± 23 pmol · min−1 · mg−1) and normal cells (172 ± 19). We conclude that skin fibroblasts from patients with this type of MODY are indistinguishable from cells of their unaffected relatives, with respect to insuinsulin binding and insulin stimulation of amino acid transport.
The Effect of Donor Strain Blood and ALS Therapy on Pancreatic Islet Allograft Survival in the Rat
Authors: Selawry Helena P , Cohen Howard L , Mui Mei Mei
Published: September 2013

Small amounts of donor strain ACI blood injected in conjunction with minimal ALS therapy prolonged islet allograft survival in Wistar-Lewis, diabetic recipients from a mean of 8 days in nontransfused rats to a mean of more than 100 days. ACI skin grafts transplanted on long-surviving transplant-improved rats were rejected within 8 days, which suggested that “classical” tolerance was probably not the mechanism responsible for the blood-induced suppression of islet allograft rejection.
The Influence of Genetic Background on the Expression of Mutations at the Diabetes Locus in the Mouse: IV. Male Lethal Syndrome in CBA/Lt Mice
Authors: Leiter Edward H
Published: September 2013

To assess whether db-induced pathogenetic changes in beta-cells were restricted to mice with H-2d haplotype, the db gene from BL/Ks was transferred into the CBA/Lt subline (H-2k). A marked sexual dimorphism was observed in the diabetes syndrome in db/db animals. Young adult db/db males exhibited an early onset and completely lethal diabetes (100% mortality by 6 mo). At 3 mo db/db males were moderately obese (43 ± 4 g) but severely hyperglycemic (475 ±69 mg/dl blood glucose) and hyperglucagonemic. Islets were atrophic, showing variable leukocytic infiltration. Although hyperinsulinemic at 2 mo, mutant males had only normal or below normal plasma insulin at 4 mo. Electron microscopic examination confirmed beta-cell necrosis and the appearance, in prenecrotic betacells, of numerous intracisternal type A (retrovirus) particles (IAP). In contrast, db/db females became increasingly obese with age but remained healthy, suffering no mortality at 6 mo. These mice were only transiently hyperglycemic and were able to sustain hyperinsulinemia. Light and electron microscopy revealed beta-cell hypertrophy that was not accompanied by increased numbers of IAP or by necrosis. Retrovirus induction therefore seemed a consequence rather than a cause of hyperglycemia.

Ovariectomy coupled with testosterone injection failed to induce severe diabetes in females; castration failed to moderate male diabetes. Instead, biweekly injections of 25 μg each of 17β-estradiol and progesterone effected complete diabetes remission in males. Experiments using cultured CBA/J islet cells did not support the hypothesis that ovarian steroids were directly protective at the beta-cell level. This study shows that db gene-induced pathogenesis is not restricted to mice with the H-2d haplotype, and that sex steroids are important modifiers of syndrome severity.
Effect of Diabetes, Insulin, Starvation, and Refeeding on the Level of Rat Hepatic Fructose 2,6-Bisphosphate
Authors: Neely Philip , El-Maghrabi M Raafat , Pilkis Simon J , Claus Thomas H
Published: September 2013

The influence of alloxan diabetes and starvation for 72 h on the level of rat hepatic fructose 2,6-bisphosphate was investigated. Both diabetes and starvation decreased the level to 10% of the value found in livers of normal, fed rats (10 nmol/g liver). The activity of the enzyme responsible for the synthesis of fructose 2,6-bisphosphate, 6-phosphofructo 2-kinase, was also decreased in livers of diabetic rats. Insulin administration for 24 h to diabetic rats restored the level of fructose 2,6-bisphosphate to normal. Refeeding a high carbohydrate diet for 24 h to starved rats resulted in fructose 2,6-bisphosphate levels that were 2.5-fold higher than that in livers of fed rats. The level of fructose 2,6-bisphosphate in diabetes and starvation, and after refeeding correlates well with the rate of glycolysis and gluconeogenesis in these states and thereby provides further support for its role in regulating hepatic carbohydrate metabolism.
Mechanism and Significance of Insulin Resistance in Non-insulin-dependent Diabetes Mellitus
Authors: Rizza Robert A , Mandarino Lawrence J , Gerich John E
Published: September 2013

To determine whether receptor and/or postreceptor abnormalities of insulin action were responsible for insulin resistance in nonobese patients with non-insulindependent diabetes mellitus (NIDDM) and to assess the role of insulin resistance in their impaired glucose tolerance, insulin dose-response characteristics, insulin binding to monocytes, and insulin secretion were compared in 10 nonobese patients with NIDDM and six age-weight-matched nondiabetic volunteers. The insulin resistance of the diabetics was characterized by a shift to the right of their insulin dose-response curve (Km 81 ± 4 μU/ml vs. 58 ± 2 μU/ml in the nondiabetics P < 0.001) but a normal maximal response to insulin. Although monocyte insulin binding was decreased in the diabetics (P < 0.01), their response to insulin was appropriate for the number of insulin receptors occupied indicating normal postreceptor function. Insulin secretion was markedly reduced in diabetic subjects (52 ± 22 vs. 471 ± 90μu.U · ml−1 · 10 mirr1 in the nondiabetic subjects, P < 0.001) and was more strongly correlated with fasting plasma glucose (r = 0.92, P < 0.001) and intravenous glucose tolerance (Kivgtt) (r = 0.98, P < 0.001) than was insulin sensitivity (Km) (r = 0.23, NS, and r = 0.57, P < 0.05, respectively). We conclude that in nonobese patients with NIDDM, insulin resistance is characterized by a shift to the right of the insulin dose-response curve, which can be accounted for solely by an insulin receptor defect. However, in these patients, impaired insulin secretion rather than insulin resistance appears to be the predominant metabolic abnormality.
The Diagnosis of Postprandial Hypoglycemia
Authors: Lev-Ran Arye , Anderson Richard W
Published: September 2013

Our observation that hypoglycemia, often self-diagnosed by our patients, was seldom confirmed led the authors to establish norms for the glucose tolerance test: We first obtained values for 650 patients who were, entirely free from symptoms before and during testing. The median nadir in this group was 64 mg/dl. Ten percent of the patients had plasma glucose nadirs of 47 mg/dl or below and 2.5% had values of 39 mg/dl or less. Utilizing these values in combination with clinical criteria, we confirmed hypoglycemia after glucose load in 16 (median nadir 39.5 mg/dl) of 118 patients presenting with this diagnosis, and only 5 of the 16 were hypoglycemic after their usual meals. The other 102 patients, whose many complaints were unrelated to measured plasma glucose levels, had nadirs similar to those of the control group Placebo tests performed on 14 nonhypoglycemic patients provoked symptoms (recorded by the patients themselves) that they considered indicative of hypoglycemia. Some accepted other diagnoses after we demonstrated that their symptoms occurred when they were normoglycemic. Since nadirs of hypoglycemibs and control subjects overlap, we conclude that accurate diagnosis of hypoglycemia requires that symptoms develop concurrently with low blood sugar and that they are absent at other times. Low plasma glucose must be considered only one of the criteria in diagnosing functional hypoglycemia along with a relationship between food intake, timing of symptoms, correlation of symptoms and low glucose levels, and reproducibility of test results.
High Density Lipoprotein Composition in Insulin-dependent Diabetes Mellitus
Authors: Eckel Robert H , Albers John J , Cheung Marian C , Wahl Patricia W , Lindgren Frank T , Bierman Edwin L
Published: September 2013

Although atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death in insulin-dependent diabetics, plasma levels of high density lipoprotein (HDL) cholesterol (an independent “negative” risk factor for ASCVD) have been reported to be normal or high. To test whether alterations in HDL composition might increase potential risk of insulin-dependent diabetics to ASCVD, their major constituent apolipoproteins, A-I and A-II, were measured and compared with levels in controls. HDL cholesterol levels were slightly higher (P = NS) in diabetics than in controls. The HDL cholesterol/LDL cholesterol ratio (an inverse index of relative risk of developing ASCVD) was significantly higher in diabetic men than in controls (P < 0.02). HDL composition differed markedly in diabetics and controls: the apolipoprotein A-I/A-II ratio was significantly higher (P < 0.001) in both diabetic men and women (diabetic men—4.1 ± 0.5, mean ± SD, controls 3.6 ± 0.4; diabetic women—4.6 ± 0.4, controls 3.9 ± 0.5). Subsequent analysis of plasma from four patients by analytic ultracentrifugation demonstrated a high correlation (r = 0.993, P < 0.01) between the apolipoprotein A-I/A-II ratio and HDL2, the cholesterol-rich lighter subclass of HDL thought to be the group of particles involved in reduced risk of ASCVD. Therefore, the alteration of HDL composition in insulin-dependent diabetics appears similar to that associated with reduced risk in nondiabetics. Thus, whether a genetic or acquired abnormality, the high apolipoprotein A-I/A-II ratio in insulin-dependent diabetics does not appear to counteract their increased risk Of developing ASCVD.
Prostacyclin Production by Isolated Adipocytes
Authors: Axelrod Lloyd , Levine Lawrence
Published: September 2013

Isolated rat adipocytes produce prostacyclin (PGI2) in relatively large quantities during norepinephrine (NE)-induced lipolysis. The endogenous NE-induced production rate of PGI2, calculated from the NE-induced production rate of PGI2 observed in our studies (2.2 ng/106 cells/2 h) and from the number of fat cells in the normal organism, is 1.46 ng/kg/min for rats, 4.46 ng/kg/min for men, and 11.86 ng/kg/min for women. These rates are comparable to the exogenous PGI2 infusion rate that alters platelet aggregation and blood pressure in rats and humans. Exogenous PGI2 failed to modify the rate of NE-induced lipolysis. Inhibition of endogenous PGI2 production by indomethacin had no effect on the rate of NE-induced lipolysis when either a maximal or submaximal lipolytic concentration of NE was used.

PGI2 [rather than prostaglandin (PG) E2] may be the substance that accounts for the functional vasodilatation that accompanies hormone-induced lipolysis. PGI2 is produced in larger quantities than PGE2 during NE-induced lipolysis and is a more potent vasodilator than PGE2. Its instability can account for the inability of previous investigators to detect a vasodilator substance in the venous effluent of adipose tissue.

The production of PGI2 by adipocytes may be an important modulator of the regulation of vascular tone and platelet aggregation by catecholamines in the vascular bed of adipose tissue and perhaps other tissues. PGI2 produced by adipocytes, by virtue of its ability to cause vasodilatation and inhibit platelet aggregation, may contribute to the maintenance of luminal patency in the vascular bed of adipose tissue and possibly other tissues as well.
Effect of Muscimol on Glucose-stimulated Somatostatin and Insulin Release from the Isolated, Perfused Rat Pancreas
Authors: Robbins Mark S , Grouse Lynette H , Sorenson Robert L , Elde Robert P
Published: September 2013

This study examines the effect of muscimol, a high affinity, specific gamma-aminobutyric acid (GABA) agonist, on glucose-stimulated somatostatin and insulin release from the isolated, perfused rat pancreas. Perfusion with low glucose (50 mg/dl) conditions resulted in basal somatostatin release of 46 ± 4 pg/ml. Basal insulin release was less than 20 μU/ml. High glucose (300 mg/dl) conditions stimulated somatostatin and insulin release. Steady-state levels of somatostatin and insulin release under high glucose conditions were 425 ± 12 pg/ml and 419 ± 18 μU/ml, respectively. Perfusion with medium containing 1 μM muscimol inhibited glucose-stimulated somatostatin release by 38%, whereas the course of glucose-stimulated insulin release was unaffected. Tentative conclusions from this study are (1) that GABA is potentially a modulator of islet somatostatin but not insulin release, and (2) the fact that somatostatin, an inhibitor of insulin, can be suppressed 38% without coincidental increase in insulin release seems to indicate that, under high glucose conditions, somatostatin is without a significant paracrine effect on the beta-cellS.
Platelet Aggregation in the Cerebral and Mesenterio Microcirculation of Mice With Genetically Determined Diabetes
Authors: Rosenblum William I , El-Sabban Farouk , Loria Roger M
Published: September 2013

Platelet aggregates were induced in pial arterioles of the following strains of mice with a genetic predisposition for diabetes: ob/ob and db+/db+. Aggregation was compared with that in 6J+/+ mice, the nondiabetic controls for ob/ob animals, and in +m/+m as well as db+/+m, the nondiabetic controls for db/db+ mice. Aggregation was also induced within mesenteric arterioles of db+/db+ animals and compared with that in db+/+m mice. Aggregation was monitored microscopically, by measuring the time required for a noxious stimulus to initiate aggregation in an injured arteriole. Platelet aggregation was initiated with equal ease in the pial arterioles of ob/ob mice and their 6J/+ controls. However, the onset of aggregation in the pial arterioles of the db+/db+ group was significantly delayed when compared with the onset in either of the nondiabetic control groups, m/m or db/m. A similar prolongation in the time required to produce aggregation was also observed in the mesenteric arterioles of the db/db+ mice when compared with db/m controls. The basis for reduced platelet aggregation in the microcirculation of db+/db+ mice is not explained. The results differ from those showing enhanced aggregation in many in vitro studies of platelets from human diabetics and from those of in vivo studies of two other animal models described in the literature. However, not all published studies have reported enhanced aggregation. The delayed aggregation in the present study may provide a basis for analysis of factors that regulate platelet aggregation in diabetes.
Microvascular Alterations Develop in Syrian Hamsters After the Induction of Diabetes Mellitus by Streptozotocin
Authors: Joyner W L , Mayhan W G , Johnson R L , Phares C K
Published: September 2013

Microvessels in the cheek pouch of the hamster were investigated to determine their structural, reactivity, and permeability characteristics after the induction of diabetes. To induce diabetes, hamsters were injected with streptozotocin (50 mg/kg body wt./day, i.p., for 3 days). Vehicle-injected, age-matched hamsters were the controls. Diabetic hamsters were characterized by elevated serum glucose (>300 mg/dl) and triglycerides and decreased serum insulin (50%). Microvascular studies were completed on cheek pouch micro-vessels suffused with Ringer's solution (37°C, pH 7.4) bubbled with 95% N2-5% CO2. Vascular dimensions and reactivity of selected arterioles and venules to microapplications of norepinephrine were determined with a video micrometer using intravital microscopy. Restrictiveness of the microvascular membranes to fluorescein-labeled dextran fractions (mol wt: 150,000; 40,000; 20,000 daltons) was measured by determining the number of leaky sites. Stimulation of membrane permeability by histamine was investigated. There were no major alterations in arteriolar lumen and wall diameters, whereas venular lumen diameters were increased in hamsters diabetic for two months. Likewise, arteriolar responses to norepinephrine were not altered by diabetes; however, venular responses were decreased at two months. The restrictiveness of the vascular membrane to various dextran fractions was dramatically decreased in the diabetic animals at two months. Histamine did not alter micro-vascular leakage in the diabetic as it did in the normal hamsters. These studies indicate that microvascular alterations, venular dilation, and increased permeability to large molecules occur in the diabetic hamster within two months after the induction of diabetes.
Hyperglycemia and Arterial Disease
Authors: Keen H , Jarrett R J , Fuller J H , McCartney P
Published: September 2013

Clinical and autopsy evidence support the increased risk of atherosclerotic disease in diabetes mellitus (DM). However, mechanisms other than arterial occlusion may also contribute to clinical syndromes often assumed to be atherosclerotic in origin. There is considerable geographical variability in the frequency of arterial disease in the diabetic. Glucose intolerance short of unequivocal DM is found in some (though not all) populations to carry increased atherosclerotic risk. Morbidity and mortality data suggest that women are particularly vulnerable (as with DM). The Whitehall prospective study of cardiovascular mortality shows that risk does not rise smoothly with increasing degrees of glucose intolerance but that it doubles sharply at the 95th percentile of the 2-h post-glucose blood sugar distribution.
The Role of Insulin in Atherosclerosis in Diabetics and Nondiabetics: A Review
Authors: Stout Robert W
Published: September 2013

Disease of coronary, cerebral, and peripheral arteries is associated with exaggerated insulin responses to oral glucose. In three populations, high fasting or post-glucose insulin levels have a predictive value in the incidence of ischemic heart disease and in cardiac mortality. Diabetics who are obese or who have received treatment with insulin have elevated insulin levels and, as a group, have an increased incidence of cardiovascular disease. Insulin, in small concentrations, has effects on arterial tissue including stimulation of smooth muscle cell proliferation and of glucose incorporation into lipid. It is suggested that insulin has a role in the development of atherosclerosis.
Cholesterol Metabolism in Diabetes Mellitus: The Role of Diet
Authors: Saudek Christopher D , Young Nancy L
Published: September 2013

There is extensive evidence that cholesterol metabolism is abnormal in diabetes. Total plasma cholesterol is elevated, and more subtle indices of sterol homeostasis are also deranged.

Insulinization of the poorly controlled diabetic reduces fecal bile acid excretion. Fecal neutral sterol excretion increases compensatorily, at least when caloric intake is maintained during insulinization. Thus, net sterol balance is not changed by insulin treatment, again assuming the diet remains constant. Other workers have found decreased sterol synthesis after insulinization if calories are reduced. Using isotopically labeled squalene turnover as a reflection of cholesterol synthesis, insulin treatment increases the flux of squalene.

Pursuing diabetes' effect on cholesterol synthesis at a more basic level, we found that HMG-CoA reductase, the rate-limiting enzyme in cholesterol synthesis, is increased in small intestine, and decreased in liver by diabetes in rats eating ad libitum.

These changes in reductase activity are due to hyperphagia (increased caloric and/or cholesterol intake), not to insulin deficiency alone, since diabetic rats restricted to a normal food intake have normal reductase activity in liver and small intestine. It appears that increased input of dietary and newly synthesized cholesterol by the small intestine raises plasma cholesterol level and represses reductase activity in liver of chronically diabetic rats.

Experiments measuring the incorporation of tritiated water into cholesterol find that diabetes has a net suppressive effect on cholesterol synthesis, consistent with insulin's increasing squalene turnover, and consistent with the suppressed liver synthesis being quantitatively more significant than increased intestinal synthesis. When dietary cholesterol intake is included in the calculation, however, hyperphagia may tip the balance in favor of increased net cholesterol input (synthesis plus diet).

We hypothesize that diet plays a central role in the diabetic's cholesterol homeostasis. The hyperphagia of experimental diabetes increases net cholesterol intake and increased HMG-CoA reductase in a hypertrophic small intestine.
Responses of the Arterial Wall to Injury
Authors: Moore Sean
Published: September 2013

Recent experimental evidence indicates that all the lesions seen in human atherosclerosis can be induced in animals by various forms of injury to the intima or endothelial lining of arteries. Dietary lipid supplement is not required for the development of lipid-rich atherosclerotic lesions in these settings. Factors present in plasma or serum may stimulate the proliferation of smooth muscle cells in the lesions similar to the invitro demonstration of smooth muscle cell proliferation in response to diabetic serum. The accumulation of lipid in lesions may relate to alteration in the glucosaminoglycan content of the neointima covered by regenerated endothelium and may be analagous to alterations in glucosaminoglycan metabolism in the arterial wall of diabetic subjects.
Long-term Study of Mortality and Vascular Complications in Juvenile-onset (Type I) Diabetes
Authors: Lestradet H , Papoz L , Hellouin De Menibus CL , Levavasseur F , Besse J , Billaud L , Battistelli F , Tric PH , Lestradet F
Published: September 2013

A cohort of 372 insulin-dependent diabetic children, diagnosed between October 1949 and December 1960, were followed-up until December 1976 by the same team of physicians. At the time of diagnosis all patients were under 16 yr of age and were given standardized treatment which did not change from 1949 to 1976. The therapy consisted of daily insulin adjustment based on clinical assessment, the degree of physical activity, and the results of semi-quantitative urine tests for sugar and ketone bodies. These tests were systematically performed before breakfast, lunch, and dinner. Diet was normal, unmeasured, rich in carbohydrates (approximately 60%), and quantitatively unrestricted unless the patient was overweight. Rates for mortality and for the principal complications among this cohort were computed by the actuarial method. During the 26 yr of study, 26 deaths occurred, 16 of which were directly connected with diabetes.

After 16 yr of follow-up, rates of proteinuria and hypertension were 4% and 2.1% respectively. The incidence of retinopathy reached 27%, including 1.5% proliferative retinopathy. After 26 yr, the rates rose to 14% for proteinuria, 16% for hypertension, and 85% for retinopathy, including 18% in the proliferative phase.
Concentration and Secretion of Gastric Somatostatin in Streptozotocin-diabetic Rats
Authors: Chiba Tsutomu , Kadowaki Seizo , Taminato Tomohiko , Abe Hiromi , Chihara Kazuo , Matsukura Shigeru , Goto Yasuo , Seino Yutaka , Fujita Takuo
Published: September 2013

Both the release and the content of gastric somatostatin were investigated in streptozotocin-diabetic rats. Fundic and antral somatostatin contents were both increased in streptozotocin-diabetic rats compared with control animals. Basal somatostatin levels in the perfusates of streptozotocin-treated animals were not significantly different from those of the control animals. However, the peak values of somatostatin release induced by 5 × 10−9 M glucagon in the diabetic animals were significantly higher than those of the controls. These results lead us to conclude that a hyperfunctioning state of the gastric D-Cells exists in hypoinsulinemic diabetes.
Primitive Islets Contain Two Populations of Cells with Differing Glucagon Immunoreactivity
Authors: Stefan Yolande , Ravazzola Mariella , Orci Lelio
Published: September 2013

Immunofluorescence staining with insulin, glucagon, and somatostatin antisera revealed different immunoreactive cell types in the pancreatic islets of the ratfish. In particular, one cell type was present that reacted with C- and N-terminal anti-glucagon sera, while another type was only detected by N-terminal anti-glucagon sera. The latter cell, however, became reactive to C-terminal anti-glucagon after proteolytic treatment of the section. A similar cell type was found in the epithelium of the pancreatic duct and of the gastrointestinal mucosa. The data indicate that among glucagon immunoreactive cells, some cells situated exclusively in the pancreas possess both Cand N-terminal glucagon immunoreactants, while in other pancreatic as well as intestinal cells, the sequence that binds C-terminal anti-glucagon serum appears masked and becomes accessible to the antibody only after proteolytic digestion.
Immunologic Potency of Recombined A- and B-Chains of Synthetic Human and Pancreatic Pork Insulins
Authors: Bauman William A , Yalow Rosalyn S
Published: September 2013

Pork insulin recombined from cleaved A- and B-chains of pancreatic insulin was shown to be identical with the pancreatic hormone both in erythrocyte receptor assays and in immunoassays employing four different antisera, including two species-specific human anti-insulin sera. Pancreatic human insulin and that prepared from recombined bacterially synthesized A- and B-chains were also indistinguishable in the same systems. This study demonstrates that the prohormone stage of either human or porcine insulin is not required to preserve potency of membrane binding or immunochemical reactivity, even employing an antiserum with marked species specificity.
Quantitative Morphology of B, A, D, and PP Cells in Infants of Diabetic Mothers
Authors: Milner R D G , Wirdnam P K , Tsanakas J
Published: September 2013

Pancreatic specimens from 34 infants of diabetic mothers (IDM) and 32 control infants of gestational ages 26–44 wk were examined histologically using immunocytochemical stains for insulin, glucagon, somatostatin, and pancreatic polypeptide (PP). Each section was divided into PP-rich and PP-poor regions that are thought to be derived from the ventral and dorsal lobes of the gland, respectively. In some of these, the fractional area (%) occupied by positively stained B, A, and PP cells was determined by automatic image analysis, and the area occupied by D cells was determined by conventional point counting. The B cell fractional area was significantly higher in the IDM in both PP-poor and PP-rich areas (P < 0.02). The fractional area of A cells in PP-poor areas and of PP cells in PPrich areas was also significantly greater in IDM (P < 0.02). The total endocrine cell fractional area was significantly greater in IDM in PP-poor but not in PP-rich regions of the pancreas. These results are not compatible with the hypothesis that maternal hyperglycemia results in specific fetal B cell hyperplasia and raise the possibility that hyperplasia of B, A, and PP cells in IDM may result from a variety of stimuli or that one stimulus acts on a pluripotential stem cell.
Effect of Experimental Diabetes on the Susceptibility of Myelin Proteins to Proteolysis
Authors: Spritz Norton , Singh Harbhajan , Marinan Barbara , Silberlicht Ira
Published: September 2013

To investigate abnormalities in peripheral nerve myelin in experimental diabetes, we studied the effects of the proteolytic enzymes trypsin and α-chymotrypsin on the proteins of this membrane, obtained from the sciatic nerves of normal rats and from animals made diabetic with streptozotocin. The dominant effect of the proteolytic enzymes was to incompletely degrade the major membrane protein (mol. wt. 28,000), with the appearance of new protein (mol. wt. 20,000). Using myelin isolated from the nerves of diabetic animals, the reaction was approximately one-half that of the controls (P < 0.01) for both enzymes. When, however, the myelin protein affected by trypsin and chymotrypsin was isolated from the membrane and then incubated with the proteolytic enzyme, its proteolysis was complete and took place at the same rate in the diabetic animals and controls. These findings suggest that, in this model of experimental diabetes, there is an alteration in the structure of peripheral nerve myelin that inhibits interaction between the protein in the membrane bilayer and two water soluble proteolytic enzymes. This alteration could not be demonstrated in protein isolated from the membrane, suggesting that the change relates to the interaction of the protein and other components of myelin, rather than to chemical alteration in the protein per se.
The Mechanism of Hyperchloremic Acidosis During the Recovery Phase of Diabetic Ketoacidosis
Authors: Oh Man S , Banerji Mary Ann , Carroll Hugh J
Published: September 2013

To determine the mechanism of hyperchloremic acidosis during recovery from diabetic ketoacidosis (DKA), serial measurements were made in eight patients of serum and urinary electrolytes and organic acids, and of urinary net acid. On admission, the average decrease in serum total CO2 was 17.5 mmol/L, corresponding to the excess anion gap, 18.5 meq/L, and the serum organic acids, 17.1 meq/L. With the treatment, the anion gap and organic acids decreased by 16.1 and 14.7 meq/L, respectively, but the serum CO2 increased only by 8.4 mmol/L; serum electrolyte balance was maintained by increase in chloride concentration. Fluid retention was insufficient to explain the disparity between the increase in CO2 and the decrease in organic acids. Renal loss of bicarbonate precursors during treatment was modest and was exceeded by renal bicarbonate production. The disparity between the increase in serum CO2 and the decrease in organic acids during treatment of DKA may be explained to a large extent by a difference in volume of distribution between bicarbonate and organic anions The renal loss of ketone anions before admission, however, is ultimately responsible for the persistence of substantial metabolic acidosis.