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

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

A Three-dimensional Analysis of Blood Vessels in Bronchioloalveolar Carcinoma

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

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

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

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

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

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

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

Renal proteinases and kidney hypertrophy in experimental diabetes

Summary IDDM is associated with an increase in kidney size, which is due to cellular hypertrophy and progressive matrix accumulation within the glomerulus and throughout the tubulointerstitium. The present study addressed the potential role of cysteine and metalloproteinases in renal hypertrophy of short-term diabetes. Three weeks after induction of streptozotocin diabetes in rats, intraglomerular gelatinase activity (streptozotocin: 23±4 vs control: 44±3 mU/g DNA) and cathepsin L + B activity (streptozotocin: 6.7±0.8 vs control: 9.3±0.7 U/g DNA) were significantly decreased. Insulin treatment completely prevented the decline in glomerular proteinase activity (gelatinase: 37±6 mU/g DNA; cathepsin L + B: 9.6±0.9 U/g DNA). In isolated proximal tubules a similar pattern of enzyme activity could be observed. Three weeks of diabetes caused a significant decline in cathepsin L + B activity (streptozotocin: 28±2 vs control: 37±3 U/g DNA). Insulin treatment again prevented the decline in these tubular proteinase activities. In parallel, kidney weight increased by 22% and glomerular protein/DNA ratio rose by 17% in untreated diabetic rats. Diabetic rats receiving insulin displayed a normal glomerular protein/DNA ratio and the kidney weight was increased by only 5%. These results show that renal hypertrophy of early diabetes is closely associated with a decline in both glomerular and tubular proteinase activity. Adequate insulin substitution prevented renal hypertrophy and the reduction in proteinase activity.Abbreviations AMC 7-Amino-4-methyl coumarin - EDTA ethylene diamine tetra-acetic acid - PMSF phenylmethylsulfonyl fluoride - TGF- transforming growth factor- - TIMP tissue inhibitor of metalloproteinases - GFR glomerular filtration rate - IDDM insulin-dependent diabetes mellitus     

Iron stores in 1359, 30- to 60-year-old Danish women: Evaluation by serum ferritin and hemoglobin

Summary Iron status, including serum (S-)ferritin and hemoglobin (Hb), was assessed in a population survey comprising 1359 nonpregnant Danish women in age cohorts of 30, 40, 50, and 60 years. S-ferritin levels were similar in 30- and 40-year-old women; they displayed a significant increase in 50-year-old women and a further significant increase in 60-year-old women. In the 30- and 40-year-old women, median S-ferritin was 38g/l, 5–95 percentile 6–135g/l; 17.2% had values < 15,g/l (i.e., depleted iron stores), 22.7% values from 15 to 30g/l (i.e., small iron stores), and 60.1% values > 30g/l (i.e., replete iron stores). In the 50-year-old women, median S-ferritin was 54g/l, 5–95 percentile 10–164g/l; 10.3% had values < 15g/l, 16.5% values from 15 to 30g/l, and 73.2% values > 30g/l. For the 60-year-old women, median S-ferritin was 84g/l, 5–95 percentile 25–249g/l; 1.6% had values < 15g/l, 8.6% values from 15 to 30g/l, and 89.8% values > 30g/l. Blood donors (n=180) had lower S-ferritin than nondonors in all age-groups (p<0.001). In the entire series, Hb levels were similar in 30- and 40-year-old women, median 137 g/l (8.5 mmol/l), 5–95 percentile 121–152 g/1 (7.5–9.4 mmol/l), and higher in 50- and 60-year-old women, median 140 g/l (8.7 mmol/l), 5–95 percentile 123-158 g/l (7.6–9.8 mmol/l) (p<0.0001). Hb values < 121 g/l (7.5 mmol/l) were observed in 3.8% of the women. Women with S-ferritin < 15 g/l (n=161) had lower Hb, median 134 g/l (8.3 mmol/l), than those with S-ferritin > 15 g/l, median 139 g/l (8.6 mmol/l) (p<0.001). Iron deficiency anemia (S-ferritin < 15 g/l and Hb < 121 g/l) was seen in 2.3% of 30- and 40-year-old women, and in 1.1% of 50- and 60-year-old women.     

A laser Doppler velocimetry study of the effect of hypoglycaemia on retinal blood flow in the minipig

Summary The effect of acute hypoglycaemia (plasma glucose <2.2mmol/l) on retinal venous blood flow in the minipig has been determined using bidirectional laser Doppler velocimetry and red free retinal photography. In six pigs the mean flow in a retinal vein increased from 19.3 (±2.8 SEM) l/min to 29.7 (±7.5) l/min during hypoglycaemia (p<0.05) with a return to 18.6 (±3.6) l/min when euglycaemia was restored. Retinal blood flow is affected by hypoglycaemia or its haemodynamic consequences.     

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

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

Age-related Variations in the Neuroendocrine Control,More Than Impaired Receptor Sensitivity,Cause The Reduction in the GH-releasing Activity of GHRPs in Human Aging

The mechanisms underlying the reduction in the GH-releasing activity of GHRPs in aging are still unclear. Aim of our study was to verify in man whether age-related impairment of the neurohormonal control of GH secretion and/or receptor alterations are involved in the reduced GH response to GHRPs in aging. To this goal, in 16 normal elderly subjects (E, 66–81 yr) and 12 young controls (Y, 24–28 yr) we studied the effects of 1.0, 2.0 and 3.0 g/kg iv Hexarelin (HEX), a synthetic hexapeptide, or GHRH, as well as the interaction among HEX (2.0 g/kg), GHRH (2.0 g/kg) and arginine (ARG, 0.5 gr/kg) on GH secretion. In Y the GH response to increasing doses of HEX (1.0 vs. 2.0 vs. 3.0 g/kg; AUC0;v–120 ± SEM: 1728.4 ± 406.4 vs. 2265.9 ± 298.4 vs. 2934.3 ± 482.2 g//L/h, p < 0.05 for 1.0 vs. 2.0 g/kg) and GHRH (649.6 ± 111.4 vs. 792.2 ± 117.6 vs. 1402.6 ± 363.0 g/L/h) showed a progressive increase. Two g/kg HEX and 1 g/kg GHRH were the maximal effective doses. Similarly, in E the GH response to increasing doses of HEX (336.7 ± 50.0 vs. 742.8 ± 157.9 vs. 1205.1 ± 178.1 g/L/h, p < 0.05 for 1.0 vs. 2 g/kg, p < 0.001 for 1.0 vs. 3.0 g/kg and p < 0.03 for 2.0 vs. 3.0 g/kg) and GHRH (183.8 ± 27.3 vs. 260.9 ± 17.3 vs. 356.1 ± 46.3 g/L/h, p < 0.005 for 1.0 vs. 3.0 g/kg and p < 0.05 for 2.0 vs. 3.0 g/kg) showed a progressive increase. In E the GH response to 3 g/kg HEX or GHRH were clearly higher than those to 2 g/kg. However, at each dose the GH responses to HEX or GHRH in E were lower (p < 0.05) than those in Y. In Y the GH response to HEX + GHRH was synergistical (4259.2 ± 308.0 g/L/h, p < 0.05). ARG strikingly potentiated the GHRH-induced GH rise (2640.8 ± 273.6 g/L/h, p < 0.01) but not the HEX-induced one (2371.7 ± 387.2 g/L/h) as well as the synergistical effect of HEX and GHRH (4009.1 ± 360.8 g/L/h). In E the GH response to HEX and GHRH was still synergistical (1947.7 ± 306.0 g/L/h, p < 0.05) but these responses were lower than those in young (p < 0.01). On the other hand, in E ARG restored the GH response to GHRH (1858.9 ± 172.8 g/L/h, p < 0.01) and even those to HEX (2069.5 ± 528.7 g/L/h, p < 0.01) and HEX + GHRH (4406.0 ± 1079.2 g/L/h, p < 0.05). Our present results indicate that the impairment of GHRP and GHRH receptor activity may have a role in the reduction of the somatotrope responsiveness in aging. However, the age-related reduction in the GH-releasing activity of GHRPs seems mainly dependent on age-related variations in the neural control, i.e. concomitant GHRH hypoactivity and somatostatinergic hyperactivity.     

Serumeisen-Normalwerte und statistische Verteilung der Einzelwerte bei Mann und Frau

Zusammenfassung Die Bestimmung der Normalwerte des Serumeisen bei 608 Erwachsenen und die Untersuchung des Verteilungstyps der Einzelwerte zeigt folgende Ergebnisse: Bei 503 Männern beträgt der Mittelwert (als arithmetisches Mittel) 109 g Fe/100 ml ±25 und der Normalbereich (als ±2 SD-Bereich) 59 bis 158 g Fe/100 ml, bei 105 Frauen 91 g Fe/100 ml±27 als Mittelwert und 37 bis 145 g Fe/100 ml als Normalbereich. Die Untersuchung der Verteilung mittelsFisher- undKolmogoroff-Test führte zur Annahme, einer näherungsweisen Normalverteilung.

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Summary The determination of normal values of serum iron in 608 adults and the examination of the frequency distribution gives the following results: the arithmetic mean in 503 male persons is 109±25 g Fe/100 ml and the normal range (2-SD-range) 59 to 158 g Fe/100 ml; in 105 female persons 91±27 g Fe/100 ml mean and 37 to 145 g Fe/100 ml normal range. The assumption of approximate normal distribution are controlled by theFisher- andKolmogoroff-test.

     

Granulocyte Elastase in Cirrhotic Patients with Spontaneous Bacterial Peritonitis

Granulocyte elastase (GE) is a powerfulproteolytic enzyme that is released by PMNs whendegranulated in infectious processes. The aim of thisstudy was to measure GE in ascites and plasma ofcirrhotic patients with spontaneous bacterial peritonitis(SBP). We studied 29 cirrhotic patients, 17 of themhaving SBP (group A). Twelve patients with noninfectedascites formed the control group (group B). At the time of diagnosis of SBP, GE levels inascites (183.17 ± 86.11 g/liter) and plasma(114.6 ± 35.99 g/liter) were higher in groupA than in group B (27.41 ± 11.54 g/liter, P< 0.00001 and 82.54 ± 20.52 g/liter, P = 0.01,respectively). Levels of GE in ascites had a high valuefor discriminating between patients with and withoutSBP. In the patients who responded to the initialantibiotic treatment, these values significantly decreasedin ascites (67.69 ± 54.22 g/liter, P = 0.003)and plasma (67 ± 22.39 g/liter, P = 0.01) 48hr after therapy was started, in parallel with thedecrease of PMN in ascites. In patients who did notrespond, the production of GE remained elevated.Patients who developed renal insufficiency following SBPhad more marked elevation of GE in plasma (144.8± 33.43 g/liter) than those with normal renalfunction (99.5 ± 27.53 g/liter, P = 0.02).These results suggest that the measurement of GE may behelpful for the diagnosis of SBP in patients withcirrhosis and for assessing the efficacy of therapy. Inaddition, the release of GE into plasma may contributeto the impairment of renal function that follows SBP insome patients.     

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

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

Secretory component and lactoferrin in pure pancreatic juice in chronic pancreatitis

To evaluate pathophysiological roles of proteins in pancreatic secretion, immunoreactive lactoferrin (LF) and secretory component (SC) were measured in the first fraction of the pure pancreatic juice obtained endoscopically from 17 control, 21 suspected (SCP), 14 noncalcified (NCP), and 14 calcified chronic pancreatitis (CCP) subjects. The protein and amylase tended to decrease both in concentration and output from control to CCP. LF concentration was elevated in CCP (18.0±4.9/ml) when compared with controls (2.3±0.2g/ml), and LF output in NCP (12.3±3.8 g/min) was increased from controls (3.8±0.6 g/min). The combination of high LF concentration with low protein output was observed in 10/14 in CCP but 0/14 in NCP and can be a biochemical discriminator of CCP from NCP. SC concentrations were also elevated in NCP (8.5±2.0 g/ml) and CCP (5.6±1.6 g/ml) from controls (1.2±0.2 g/ml). SC outputs in SCP (9.8±3.1 g/min) and NCP (21.1±4.8 g/min) were increased from controls (1.7±0.3 g/min), but there was no further increase in CCP. Hypersecretion of LF and SC in chronic pancreatitis is different, especially in CCP, although the mechanisms for hypersecretion are unknown.This study was supported in part by a research grant for intractable pancreatic disease from the Ministry of Health and Welfare, Japan.     

Adenosine-induced increase in myocardinal ATP: Are there beneficial effects for the ischaemic myocardium?

Summary The adenosine triphosphate (ATP) content of isolated Langendorff-perfused rat hearts may be increased by more than 40% above the normal value by a 2-h perfusion with adenosine (15 mol/l). This metabolic manipulation was used to investigate the hypothetical relationship between total tissue ATP content and ischaemia-induced contractile failure, ischaemic contracture and post-ischaemic functional recovery.Adenosine perfused hearts were submitted to 20 min of normothermic ischaemia and reperfused for 45 min with or without adenosine. Control experiments were performed with adenosine-free preischaemic perfusion. In identically designed experiments the tissue-protective effect of diltiazem (0.5 mol/l) was determined and compared with the experiments with adenosine.At the end of 120 min of preischaemic perfusion, the ATP content of the adenosine treated hearts was 34.3±1.8 mol/g dry weight (control=23.6±1.9 mol/g, p<0.01). After a period of 20 min of normothermic ischaemia, the ATP content of the adenosine hearts decreased to 13.3± .4 mol/g, whereas ATP fell to 8.3±1.6 mol/g in the control hearts. The creatine phosphate (CP) levels of adenosine hearts were significantly lower than those of the control group before ischaemia, but did not show major differences following ischaemia.During ischaemia, the contractile activity measured via an intraventricular balloon catheter, as well as ischaemic contracture did not differ between the adenosine and control hearts. The inclusion of diltiazem into the perfusate significantly delayed the onset of contracture.After 45 min of reperfusion, ATP contents of adenosine and control hearts reached similar values (8.4±2.3 and 8.3±2.9 mol/g, respectively). Inclusion of adenosine (15 mol/l in the reperfusion perfusate of the adenosine experiments prevented a further decrease, but did not increase tissue ATP content. CP values of all groups showed a partial recovery upon reperfusion, they did not differ significantly.Contractile recovery was equal in all experimental groups except for the diltiazem treated hearts, which showed during the first 10 min of reperfusion an improved mechanical performance.It is concluded that total tissue ATP is not necessarily a good indicator of functional capabilities under conditions of normothermic ischaemia and reperfusion in the isolated rat heart.This work was supported in part by grants from the British heart foundation, the British Council and the St. Thomas, Hospital Research Endowments Fund. The advice and assistance of Dr. M. Curtis and Mrs. C. Erlebach are gratefully acknowledged.     

Gastric diversion or pylorus ligation for gastric mucosal integrity and acid secretion studies in the rat?

The advantages of gastric diversion over pylorus ligation in rat gastric mucosal integrity and acid secretion studies over 6 hr were investigated. Mucosal injury developed in 80% of pylorus-ligation controls. Atropine (5 mg/kg) or cimetidine (40 mg/kg) had no effect on this injury (2.9 mm²±0.9 and 2.8 mm²±0.7, respectively, vs 3.1 mm²±1, mean±sem, N=10; however vagotomy increased it (13.7 mm²±Pylorus-ligation H⁺ output was higher than that of gastric diversion (390.5 mol±54.8 vs 61 mol±2.5, mean±sem, N=10, P<0.001). Cimetidine (40 mg/kg) depressed H⁺ output of gastric diversion (21.3 mol±1.2 vs 61 mol±2.5, mean±sem, N=10, P<0.001), but not of pylorus ligation (424 mol±74.2 vs 390.5 mol±54.8, mean±sem, N=10). Vagotomy or atropine depressed pylorus-ligation H⁺ output (P<0.001), but each allowed an output (36.6 mol±5.5 and 120 mol±29, respectively, mean±sem, N=10) significantly (P<0.001) higher than that associated with it in gastric diversion (16 mol±1.4 and 17.1 mol±1.6, respectively, mean±sem, N=10). This study demonstrates that in the rat pylorus ligation, in contrast to gastric diversion, injures the gastric mucosa, stimulates H⁺ secretion, and overshadows the efficacy of antisecretory agents.     

B cell adrenoceptors and sulphonylurea-induced insulin release in mouse islets

Summary Interactions of tolbutamide and glibenclamide with B cell adrenoceptors have been reported. This study evaluated the possible role of such interactions in the stimulation of insulin release. Mouse islets were incubated in the presence of 10 mmol/l glucose alone or with tolbutamide (10 mol/l) or glibenclamide (0.02 mol/l). At 0.01–10 mol/l, blockers of ₂-adrenoceptors (yohimbine, idazoxan) or ₁-adrenoceptors (prazosin) had practically no effect on glucose-induced insulin release and did not affect its potentiation by sulphonylureas, except for a slight increase by 10 mol/l prazosin and idazoxan. Nonspecific -blockers (phentolamine, dihydroergotamine) increased control release at 10 mol/l, but only the latter amplified the response to tolbutamide. Blockers of -adrenoceptors were tested at 0.1–100 mol/l: propranolol (₁, ₂), metoprolol (₁) and compound ICI 118-551 (₂). They increased glucose-induced insulin release at 100 mol/l but variably altered the effect of sulphonylureas. Blockers of adrenoceptors have, thus, no effect on insulin release in vitro at therapeutic concentrations. At high concentrations, they non-specifically affect the action of sulphonylureas. We conclude that an interaction with B cell adrenoceptors is not involved in the insulinotropic action of sulphonylureas.     

Increase in insulin response after treatment of overt maturity-onset diabetes is independent of the mode of treatment

Summary The changes in insulin response to a 100 g glucose tolerance test after treatment by diet, sulphonylurea and insulin were compared in non-ketotic diabetic patients who had fasting blood glucose concentrations higher than 160 mg/100 ml. Patients were selected so that their pre-treatment and post-treatment blood glucose levels were comparable between different treatment groups. Their insulin responses were poor initially but increased significantly when the diabetic state was improved by each treatment. The degree of improvement of insulin response was similar between different treatment groups, when their fasting blood glucose decreased below 140 mg/100 ml and the glucose tolerance curves were improved to a similar extent. Preand post-treatment IRI values (sum of insulin values during glucose tolerance test, mean±SD) were 102±50 and 200±37 U/ml in diet-treated group (n = 28), 90±40 and 195±53 U/ml in sulphonylurea-treated-group (n=48), and 83±28 and 193±38 U/ml in insulin-treated group (n = 13), respectively. The data suggest that the poor insulin response in overt diabetes results not only from an inherent insensitivity of B-cells to glucose but also from the metabolic derangement of diabetes. Poor insulin response and overtly diabetic metabolism seems to form a vicious cycle.     

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

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

Elevated serum homocysteine levels for gouty patients

Our objective was to analyze serum total homocysteine (tHcy) levels for gouty patients and to study whether there are any level changes following treatment with allopurinol. We enrolled 90 male participants including patients with primary gout (n=51) and community-based healthy controls (n=39). Fasting tHcy levels were determined for all subjects and repeat measurements performed for 29 patients following treatment with allopurinol. The results revealed that gouty patients exhibited significantly greater serum tHcy levels (12.10±3.19 mol/l) than healthy controls did (9.96±2.16 mol/l) (p=0.0003), although there was no obvious difference between the pre-allopurinol treatment group (12.54±3.31 mol/l) and its post-treatment analogue (11.90±4.68 mol/l) (n=29, p=0.33). Elevated serum levels of tHcy were noted for this cohort of male gouty patients as compared to healthy controls, and these tHcy levels did not appear to change substantially following treatment with allopurinol. Although the pathogenesis of hyperhomocysteinemia for gouty patients still remains somewhat obscure, this study suggests that tHcy levels cannot be effectively modulated by treatment with allopurinol.