Tannin inhibition of protein kinase C in airway epithelium

Tannin, a polydisperse polyphenol extracted from cotton bracts (CBE), has been implicated in the pathogenesis of byssinosis, a lung disease of mill workers. CBE tannin inhibits chloride secretion in airway epithelial cells by means of an unknown mechanism(s). Activation of protein kinase C (PKC) by PMA (phorbol 12-myristate 13-acetate) in airway cells increases chloride secretion. The effect of tannin on this PKC pathway was examined, using canine tracheal epithelium mounted in Ussing chambers. PMA addition (10 nM) to the mucosal bath resulted in a 0.36 ± 0.07 Eq/cm² · h (mean ± SEM, n = 20) increase in short-circuit current (I_sc) and a 0.38 ± 0.17 Eq/cm² · h increase in net chloride secretion (J_net). The inactive 4-phorbol had no effect. Tannin addition to the mucosal bath produced a dose-dependent decrease in I_sc and J_net. In tissues pretreated with 2–50 g/ml tannin, and subsequently stimulated with PMA, tannin inhibited PMA stimulation of chloride secretion beginning at a tannin concentration of 10 g/ml (0.09 ± 0.05 Eq/cm² · h [n = 10] increase in I_sc and 0.08 ± 0.03 Eq/cm² · h increase in J_net with PMA after tannin pretreatment). At 50 g/ml tannin, the stimulatory effect of PMA was completely abolished. The known PKC inhibitor, H-7 (20 M), inhibited PMA stimulation, while chelerythrine (2 M) had not effect on PMA-stimulated I_sc and J_net, and calphostin C was toxic to the airway epithelium. In membrane fragments, 2.5 g/ml tannin inhibited the rate of histone III phosphorylation by PMA from 32.1 ± 4.4 nmol/mg protein per min to 20.1 ± 2.7 nmol/mg protein per min (n = 7). In bovine airway cells, tannin pretreatment (2.5 g/ml) decreased the cytosolic activity of PKC but had no effect on PKC translocation to the membrane. We conclude that tannin inhibits chloride secretion in airway epithelial cells in part by inhibiting PKC.Offprint requests to: Michelle M. Cloutier     

Efficacy and Tolerability of the Long-Acting Somatostatin Analog Lanreotide in Acromegaly. A 12-Month Multicenter Study of 58 Acromegalic Patients

Objective: To determine the effects of the new somatostatin analogue, lanreotide, in its prolonged released form (PR), in patients with acromegaly.Design: Prospective open multicenter non comparative study.Setting: Thirty-three university-affiliated medical centers.Patients: One hundred sixteen acromegalic patients with active disease, of whom 58 patients complied with the protocol and completed the 12-month period treatment.Intervention: Lanreotide PR treatment was started at a dose of 30 mg intramuscularly every 14 days. If integrated mean plasma GH levels were not below 5 g/L and/or IGF-I levels were not normalized after one month of treatment, injections were given every 10 days. The duration of the study was 12 months.Results: After one month of treatment mean plasma GH and IGF-I levels had fallen from 10.7 ± 11.1 g/L (mean ± SD; range, 2.6 – 74.8 g/L; median, 7 g/L) and 718 ± 270 g/L (range 338 – 1440 g/L; median, 645 g/L), respectively, to 7.8 ± 10.1 g/L and 575 ± 252 g/L, respectively. Thirty patients (22%) had plasma GH levels below 2.5 g/L, and 8 patients (16%) had age-adjusted normal plasma IGF-I levels. At the sixth month of treatment mean plasma GH levels of 2.5 g/L or less, and normal plasma IGF-I levels were observed in 33%, and 33% of patients, respectively. At the twelvth month of treatment, these percentages were 41%, and 41%, respectively. The interval between two injections was shortened (one injection every 10 days) in 8 of the 58 patients (13%) at the second month of treatment, and at the end of the study, 70% of patients required 3 injections per month. The most frequent adverse event elicited by enquiry was transient diarrhea (76% of patients), followed by abdominal pain (62%) and pain at the injection site (59%). Based on the analysis of a subgroup of 46 patients who had at least a measurement of fecal fat content after day 0 of the study, a non significant increase (from 4.2 ± 3.4 to 5.1 ± 4.3 g/24h, p = 0.3) in mean steatorrhea was observed during treatment. Before treatment, steatorrhea was present in 9 (19%) patients. During the study, 15 additional patients (32%) developed persistent steatorrhea, and there was a transient increase in fecal fat content above 6 g/24 h in another 11 patients. After exclusion of the 7 patients (12%) with gallstones at enrolment, new gallstones were diagnosed in 6 out of 50 patients (12%) during the study.Conclusion: Two or three monthly injections of lanreotide PR decreased GH concentration to less than 2.5 g/L and normalized IGF-I levels in 41% of patients treated during 12 months. The good tolerability of this treatment, and the reduction in the frequency of injections, plus the sustained drug serum concentrations, confirm the usefulness of this new somatostatin analog formulation.     

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.     

Comparison Between Ischaemic and Anisomycin-Induced Preconditioning: Role of p38 MAPK

To further evaluate the significance of p38 MAPK as trigger or mediator in ischaemic preconditioning, anisomycin and SB 203580 were used to manipulate its activation status. Special attention was given to the concentration of the drugs and protocols used.The isolated perfused rat heart, subjected to either 25 min global ischaemia or 35 min regional ischaemia, was used as experimental model. This was preceded by anisomycin (2 or 5 M: 3 × 5 min; 5 M: 5 min or 10 min; 5 M: 10 min + 10 min washout or 20 M: 20 min) or SB 203580 (2 M: 3 × 5 min; before and during 3 × 5 min or 1 × 5 min ischaemic preconditioning; 10 min). Endpoints were functional recovery during reperfusion and infarct size.Anisomycin, regardless of the protocol, reduced infarct size, but did not improve functional recovery. In a number of experiments activation of JNK by anisomycin was blocked by SP 600125 (10 M). SP 600125 had no effect on the anisomycin-induced reduction in infarct size. SB 203580 when administered for 10 min before sustained ischaemia, improved functional recovery and reduced infarct size. SB 203580 could not abolish the beneficial effects of a multi-cycle preconditioning protocol, but it significantly reduced the outcome of 1 × 5 min preconditioning. In all hearts improved functional recovery and reduction in infarct size were associated with attenuation of p38 MAPK activation during sustained ischaemia-reperfusion.The results indicate that activation of p38 MAPK acts as a trigger of preconditioning, while attenuation of its activation is a prerequisite for improved recovery and a reduction in infarct size.     

Effect of luminal acidification on guinea pig gastric mucosa

H⁺ secretion was studied in guinea pig fundic mucosa incubated in (A) bicarbonate-Ringer's gassed with 95% O₂-5% CO₂, or (B) HEPES gassed with 100% O₂ before and after luminal pH was lowered to 2.0 for periods up to 90 min. At pH 2.0 for 60 min, H⁺ secretion in group A tissues fell by 35±4% (P=0.02) from a control rate of 1.35±0.09 eq/cm²/hr and in group B tissues by 50±11% (P=0.01) from a control rate of 1.59±0.08 eq/cm²/hr. After 90 min at pH 2.0, H⁺ secretion in group A fell by 53±8% (P=0.02) from a control rate of 1.47±0.07 eq/cm²/hr and in group B fell by 44±6% (P=0.01) from a control rate of 1.38±0.07 eq/cm²/hr. Histamine 1×10^–4 M stimulation following exposure to pH 2.0 for 90 min increased secretion in group A tissues from 0.80 ±0.14 to 1.06±0.13 eq/cm²/hr (P<0.05), compared with an increase in nonacidified controls from 1.15±0.22 to 1.80±0.20 eq/cm²/hr (P<0.05) and in group B tissues from 1.27±0.10 to 1.56±0.19 eq/cm²/hr (P<0.05) compared with nonacidified controls from 1.43±0.22 to 2.23±0.41 eq/cm²/hr (P<0.05). Secretory function and electrical characteristics were adversely affected by luminal acidification to pH 2.0 and suggested a breach in the mucosal barrier with damage to parietal cells.This study was funded by the National Institute of Health Grant No. AM 15681.     

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     

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.     

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.     

Thin myofilament proteins in norm and heart failure I. Polymerizability of myocardial Straub actin in acute and chronic heart failure

Summary The reduced and intrinsic viscosities of myocardial Straub F-actin from the left ventricle of a practically healthy man were equal to 3.05±0.2 and 2.4±0.32 and from the right ventricle were 2.37±0.2 and 2.1±0.3 dl/g, respectively (the difference between ventricles was not significant). The average length of filaments measured by flow birefringence technique was equal to 1.3±0.04 m, the number-average length (Ln), determined by the electron microscopy was 1.4 m, the weight-average length (Lw), was 2 m and the maximal one was 5.5 m. The histograms showed that the most characteristic length was that of 0.8–1.2 m.According to the flow birefringence data canine myocardial F-actin had a length similar to that of myocardial F-actin from a practically healthy man, though its reduced and intrinsic viscosities were higher.In acute and especially chronic congestive heart failure the actin polymerizability was sharply reduced. In consequence, in acute heart failure the number-average length of F-actin filaments was decreased by 43% and in congestive heart failure by 65.7%.The characteristic length in acute heart failure shifts to the range of 0.2–0.6 m, while in congestive heart failure the range is 0.2–0.4 m. This fact can possibly explain why during preparation of actin from the pathologically changed myocardium according to the methods including purification by the cycles of polymerization-sedimentation-depolymerization, the pathologically changed actin is discarded and the normal actin remains.A definite parallel was observed between the reduction of actin polymerizability and the ability of myocardial glycerinated fiber bundles (MBGF) to generate force.We conclude that the changes of actin properties in heart failure may cause a decrease in contractibility of the myocardial contractile protein system.     

Acid-Independent Gastroprotective Effects of Lansoprazole in Experimental Mucosal Injury

The protective effects of the proton pumpinhibitor lansoprazole on gastric mucosal damage inducedby ethanol-HCl or hemorrhagic shock were investigated inthe present study. The morphometric analysis of gastric histological sections revealed thatlansoprazole dosedependently reduced mucosal injuryevoked by ethanol-HCl (ED₅₀ = 24.3mol/kg) or hemorrhagic shock (ED₅₀ = 38.9mol/kg), these effects being associated with markedincrements of Alcian blue recovery from gastric boundmucus (ED₅₀ = 31.4 mol/kg and 27.6mol/kg, respectively). In addition, lansoprazoleinhibited gastric acid secretion from pylorusligated rats(ED₅₀ = 9.8 mol/kg). Further experiments,performed on rats with ethanol-HCl-induced gastricinjury, indicated that the protective effects of lansoprazole were not modified by L-365,260,suramin, N^G-nitro-L-arginine, or systemicablation of capsaicin-sensitive sensory nerves, whereasthey were partly blocked by indomethacin and fullyprevented by N-ethyl-maleimide. In addition, lansoprazoledid not modify somatostatin concentrations in gastricmucosa. The present results provide evidence thatlansoprazole prevents the necrotic damage of gastric mucosa induced by ethanol-HCl or hemorrhagicshock. According to the rank order of ED₅₀values, these effects appear to depend mainly on theenhancement of the gastric mucus barrier rather than on the reduction of acid secretion. It is alsoproposed that an increased production of prostaglandins,as well as an increased availability of sulfhydrylcompounds at level of gastric mucosa may account for the gastroprotective effects oflansoprazole.     

Inhibition of biliary phospholipid and cholesterol secretion by cefoperazone

The effect of cefoperazone, a third-generation cephalosporin, on biliary lipid secretion in rats was examined. Rats were anesthetized with ether and the mid-lumbar vein and common bile duct cannulated. Bile acid secretion was maintained by intravenous taurocholic acid infusion (28 mol/hr). A 1-hr control period was followed by intravenous cefoperazone infusion at either submaximal (20 mol/hr), or supramaximal (60 mol/hr) concentrations. At the cefoperazone infusion rate of 20 mol/hr (biliary secretion of 7.1±1.6 mol/hr) phospholipid secretion fell 19% and cholesterol secretion fell 31%; at a cefoperazone infusion rate of 60 mol/hr (biliary secretion rate of 27.1±5.1 mol/hr) phospholipid and cholesterol secretion were further reduced 40% and 56%, respectively, of controls. All changes were significant (P<0.01). Inhibition of both cholesterol and phospholipid secretion paralleled each other, was dose-dependent, and reversible. Cefoperazone's inhibitory action was abolished at a bile acid infusion rate of 108 mol/hr. Cefoperazone was not found to be associated with bile acid micelles or mixed micelles as determined by ultracentrifugation and gel filtration. Thus, the effect of cefoperazone on biliary lipid secretion is not due to the impairment of mixed micelle formation in the canalicular lumen but rather its inhibitory effect appears to be due to a presecretory event.     

Loss of glycogen during preconditioning is not a prerequisite for protection of the rabbit heart

Depletion of gycogen has been proposed as the mechanism of protection from ischemic preconditioning. The hypothesis was tested by seeing whether pharmacological manipublation of preconditioning causes parallel changes in cardiac glycogen content. Five groups of isolated rabbit hearts were studied. Group 1 experienced 30 min of ischemia only. Group 2 (PC) was preconditioned with 5 min of global ischemia followed by 10 min of reperfusion. Group 3 was preconditioned with 5 min exposure to 400 nM bradykinin followed by a 10 min washout period. Group 4 experienced exposure to 10 M adenosine followed by a 10 min washout period, and the fifth group was also preconditioned with 5 min ischemia and 10 min reperfusion but 100 M8-(p-sulfophenyl) theophylline (SPT), which blocks adenosine receptors, was included in the buffer to block preconditioning's protection. Transmural biopsies were taken before treatment, just prior to the 30 min period of global ischemia, and after 30 min of global ischemia. Glycogen in the samples was digested with amyloglucosidase and the resulting glucose was assayed. Baseline glycogen averaged 17.3±0.6 mol glucose/g wet weight. After preconditioning glycogen decreased to 13.3±1.3 mol glucose/g wet weight (p<0.005 vs. baseline). Glycogen was similarly depleted after pharmacological preconditioning with adenosine (14.0±1.0 mol glucose/g wet weight, p<0.05 vs. baseline) suggesting a correlation. However, when proconditioning was performed in the pressence of SPT, which blocks protection, glycogen was also depleted by the same amount (13.3±0.7 mol glucose/g wet weight, p=ns vs. PC). Bradykinin, which also mimics preconditioning, caused no depletion of glycogen (16.3±0.8 mol glucoseig wet weight, p=ns vs. baseline). Because preconditioning with bradykinin did not deplete glycogen and because glycogen continued to be low when protection from preconditioning was blocked with SPT, we conclude that loss of glycogen per se does not cause the protection of preconditioning.     

Pharmacological evidence for beta3 adrenoceptors in the control of rat gastric acid secretion

The effect of the ₃-adrenoceptor agonist BRL37344 on gastric acid secretion evoked by different secretory stimuli was investigated in anaesthetized rats with lumen-perfused stomachs in comparison with the ₂-adrenoceptor agonist clenbuterol. Intravenous injections of BRL37344 (1–10 mol/kg) and clenbuterol (0.01–1 mol/kg) dose-dependently reduced 2-deoxy-D-glucose-induced acid secretion, with BRL37344 about forty times less potent than clenbuterol. BRL37344 (0.1–3 mol/kg) inhibited pentagastrin-induced acid output, whereas clenbuterol was effective only at high doses (10–100 mol/kg). The inhibitory effect of BRL37344 on pentagastrin-induced acid secretion was not modified by the nonselective –adrenoceptor antagonist propranolol, but it was prevented by bupranolol, a ₃-adrenoceptor antagonist. Furthermore, neither BRL37344 (10 mol/kg) nor clenbuterol (100 mol/kg) modified the acid secretion induced by histamine. These data suggest that ₃ adrenoceptors have an inhibitory role in the control of rat gastric acid secretion induced by indirect stimuli.     

Antiplatelet and Antithrombotic Activity of Cilostazol is Potentiated by Dipyridamole in Rabbits and Dissociated from Bleeding Time Prolongation

Purpose: To determine the antiplatelet effect of cilostazol (Pletal^®) and its interaction with dipyridamole in in vitro and in vivo rabbit models, and to see if it can be dissociated from bleeding time prolongation.Methods: In vitro collagen-induced platelet aggregation was measured by an impedance-based aggregometer. The in vivo antithrombotic effect was evaluated in a rabbit carotid artery cyclic flow reduction (CFR) model, in which repetitive thrombosis was induced by mechanical injuries of the artery and stenosis. Template bleeding time was determined in rabbit ear arterioles and hindlimb nail cuticles.Results: In vitro platelet aggregation was slightly inhibited by 4 M cilostazol (22 ± 6%), and modestly by 13 M (57 ± 3% of aggregation). While dipyridamole itself up to 13 M had no significant inhibition, it potentiated the effect from cilostazol: in the presence of 4 M dipyridamole, 4 M cilostazol inhibited aggregation by 47 ± 6%. Dipyridamole also potentiated the CFR reducing effect of cilostazol: combination of dipyridamole (no effect by itself) and cilostazol at 1 M decreased CFRs to levels achieved by 3–4 M cilostazol alone. Bleeding times were similar in controls and animals treated with cilostazol, or with cilostazol and dipyridamole. In contrast, aspirin (4 mg/kg), while reducing CFRs, significantly increased bleeding time.Conclusion: These results suggest that dipyridamole potentiates the antiplatelet effect of cilostazol without prolongation of the bleeding time, implying a potential novel combination antithrombotic therapy.     

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.     

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.     

Time Course of GH and IGF-1 Levels Following Withdrawal of Long-Acting Octreotide in Acromegalic Patients

Aim: Several studies have demonstrated the efficacy of octreotide LAR administered intramuscularly at 4-week intervals in the treatment of acromegaly. In contrast, few data are available on the time course of GH and IGF-1 plasma levels following octreotide LAR withdrawal. This prompted us to study these parameters for up to 20 weeks following drug withdrawal in a group of 18 acromegalic patients treated for one yearDesign and patients: We studied 18 patients treated with octreotide LAR 10 mg (n = 2), 20 mg (n = 15) and 30 mg (n = 1) every 4 weeks for one year. GH (mean level during a 4-hour daily profile) and IGF-1 concentrations were measured at the end of treatment, just before the last injection (baseline) and then 15 ± 2weeks (first control) after the last injection. In patients with GH levels below 2.5 g/L and/or normal IGF-1at the first control, a second control was performed four to eight weeks later.Results: After one year of treatment with octreotide LAR, the mean plasma GH concentration was 1.91 ± 1.25 g/L (mean ± SE) and the mean IGF-1 concentration was 440 ± 251 g/L. Among the 18 patients, 13 had mean plasma GH concentrations below 2.5 g/L and seven could be considered as well-controlled (normal IGF1 and mean GH levels below 2.5 g/L). After treatment withdrawal, the plasma GH concentration remained below 2.5 g/L at the first and the second controls in 2 of the 13 (15%) patients with suppressed GH levels on baseline. Among the seven well-controlled patients on baseline (GH levels below 2.5 g/L and normal IGF-1), one (15%) remained well-controlled, one (15%) kept GH levels below 2.5 g/L but increased IGF-1 levels, and one (15%) kept normal IGF-1 levels but increased mean GH levels at the first control. This hormonal status remained unchanged at the second control in these 3 patients.Conclusions: These results show long-lasting suppression of GH secretion after treatment withdrawal in some acromegalic patients treated for 12 months with octreotide LAR. The duration of GH suppression after treatment withdrawal is variable. Mean GH levels remained below 2.5 g/L in 15% of our patients for up to 21 weeks following withdrawal of octreotide LAR. In practice, it may be preferable to wait several months after long-acting somatostatin analog withdrawal before reassessing hormone status. Owing this long-lasting effect, a dose reduction to 10 mg and/or a longer interval between injections could be considered for very good responders, as this would lead to considerable cost savings without affecting GH or IGF-1 control.on behalf of the French Octreotide LAR Group (See appendix)     

Ergonovine-induced constrictions of epicardial coronary arteries in conscious dogs: α-adrenoceptors are not involved

Summary The effect of i.v. ergonovine tartrate infusions (0.05–20 g/kg/min, 12 minutes duration) on coronary arteries was studied in 14 conscious dogs instrumented to continuously measure vascular diameter by an ultrasonic dimension gauge using 10-MHz piezoelectric crystals.Ergonovine induced a biphasic coronary response: small, transient dilation during the first minutes of infusion, followed by slowly developing constriction reaching its maximum 5 to 15 minutes after the end of the infusion and persisting at this level for at least 10 minutes. The threshold dosage for significant constriction was 0.05 g/kg/min. A dosage of 5 g/kg/min (cumulative 60 g/kg, corresponding to 35 g/kg ergonovine maleate) caused a decline in mean left circumflex artery diameter by 137±15 m (=4.6%) without significantly altering heart rate, plasma catecholamines or plasma renin activity. Coronary venous O₂ saturation did not decline, indicating the absence of coronary resistance vessel constriction. The epicardial artery constriction was not attenuated by a vasopressin antagonist. Under adrenergic blockade (2 mg/kg phentolamine and 2 mg/kg nadolol) or under ganglionic blockade (5 mg/kg pentolinium tartrate), ergonovine (5 g/kg/min) caused substantial elevation in mean arterial pressure, while the decline in coronary artery diameter was attenuated. When this increase in arterial pressure was prevented by appropriate bleeding, the ergonovine-induced coronary constriction was not diminished by adrenergic or ganglionic blockade. The serotonin antagonist methysergide (0.5 mg/kg) completely abolished the ergonovine-induced coronary artery vasomotion.It is concluded that ergonovine in dogs causes an epicardial coronary artery constriction comparable to the diffuse coronary artery narrowing in men not suffering from variant angina pectoris. These constrictions are not mediated by an adrenergic mechanism.Supported by Deutsche Forschungsgemeinschaft. Dedicated to Prof. Dr. A. Fleckenstein on the occasion of his 65th birthday.     

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     

Granulocyte elastase in assessment of severity of acute pancreatitis

Complexes of granulocyte elastase and ₁-antitrypsin are markers for granulocyte activation. In 75 patients with acute pancreatitis these complexes were immunologically determined daily in plasma during the first week of hospitalization. Patients were classified into three groups: mild pancreatitis (I, 1 complication, N=34), severe pancreatitis (II, 2 complications, N= 29), lethal outcome (III, N=12). Initially, granulocyte elastase (mean±sem) was lower in group I (348±39 g/liter) as compared to groups II (897±183 g/l) and III (799±244 g/liter), P<0.001 for I vs II + III. Initial elastase concentrations >400 g/liter were consistent with a severe or fatal course of the disease but did not distinguish between severe and lethal pancreatitis. In patients with mild or severe disease, mean elastase concentrations decreased continuously during the following days (197±15 g/liter in mild cases, 325±30 g/liter in severe cases at day 7). In patients with lethal disease, however, mean elastase concentrations even increased at day 2 and remained higher than 700 g/liter during the observation period. At days 1 and 2 the predictive value for severe or lethal disease of raised (>400 g/liter) elastase concentrations [positive predictive value (PPV) 82%, negative predictive value (NPV) 81%] was better than that of elevated (>100 mg/liter) C-reactive protein (PPV 73%, NPV 73%), elevated (>4.0 g/liter) ₁-antitrypsin (PPV 59%, NPV 50%), or decreased (<1.5 g/liter) ₂-macroglobulin (PPV 82%, NPV 67%). When the time course of the concentrations of the acute-phase proteins was studied, it was found that rises of granulocyte elastase were followed by elevated C-reactive protein levels after one day, by elevated ₁-antitrypsin levels after two days and by decreased ₂-macroglobulin levels after three to four days. We conclude that granulocyte elastase is a good early marker for the severity of acute pancreatitis. Compared with elevated levels of C-reactive protein and ₁-antitrypsin release of granulocyte elastase reflects an event that precedes acute-phase protein induction.