Pharmacological Characterization of SDX-7320/Evexomostat: a Novel Methionine Aminopeptidase Type 2 Inhibitor with Anti-Tumor and Anti-Metastatic Activity

Methionine aminopeptidase type 2 (MetAP2) is a ubiquitous, evolutionarily conserved metalloprotease fundamental to protein biosynthesis which catalyzes removal of the N-terminal methionine residue from nascent polypeptides. MetAP2 is an attractive target for cancer therapeutics based upon its over-expression in multiple human cancers, the importance of MetAP2-specific substrates whose biological activity may be altered following MetAP2 inhibition, and additionally, that MetAP2 was identified as the target for the anti-angiogenic natural product, fumagillin. Irreversible inhibition of MetAP2 using fumagillin analogs has established the anti-angiogenic and anti-tumor characteristics of these derivatives, however, their full clinical potential has not been realized due to a combination of poor drug-like properties and dose-limiting CNS toxicity. This report describes the physicochemical and pharmacological characterization of SDX-7320 (evexomostat), a polymer-drug conjugate of the novel MetAP2 inhibitor (MetAP2i) SDX-7539. In vitro binding, enzyme and cell-based assays demonstrated that SDX-7539 is a potent and selective MetAP2 inhibitor. In utilizing a high molecular weight, water-soluble polymer to conjugate the novel fumagillol-derived, cathepsin-released, MetAP2i SDX-7539, limitations observed with prior generation, small-molecule fumagillol derivatives were ameliorated including reduced CNS exposure of the MetAP2i, and prolonged half-life enabling convenient administration. Multiple xenograft and syngeneic cancer models were utilized to demonstrate the anti-tumor and anti-metastatic profile of SDX-7320. Unlike polymer-drug conjugates in general, reductions in small molecule-equivalent efficacious doses following polymer conjugation were observed. SDX-7320 has completed a Phase 1 clinical safety study in late-stage cancer patients and is currently being evaluated in multiple Phase 1b/2 clinical studies in patients with advanced solid tumors.

First-in-human study of a pharmacological duodenal exclusion therapy shows reduced postprandial glucose and insulin and increased bile acid and gut hormone concentrations

AIMS

To address the need for noninvasive alternatives to metabolic surgery or duodenal exclusion devices for the management of type 2 diabetes (T2D) and obesity by developing an orally administered therapeutic polymer, GLY-200, designed to bind to and enhance the barrier function of mucus in the gastrointestinal tract to establish duodenal exclusion noninvasively.

MATERIALS AND METHODS

A Phase 1, randomized, double-blind, placebo-controlled, single- (SAD) and multiple-ascending-dose (MAD) healthy volunteer study was conducted. In the SAD arm, four cohorts received a single dose of 0.5 g up to 6.0 g GLY-200 or placebo, while in the MAD arm, four cohorts received 5 days of twice-daily or three-times-daily dosing (total daily dose 2.0 g up to 6.0 g GLY-200 or placebo). Assessments included safety and tolerability (primary) and exploratory pharmacodynamics, including serum glucose, insulin, bile acids and gut hormones.

RESULTS

No safety signals were observed; tolerability signals were limited to mild to moderate dose-dependent gastrointestinal events. In the MAD arm (Day 5), reductions in glucose and insulin and increases in bile acids, glucagon-like peptide-1, peptide YY and glicentin, were observed following a nonstandardized meal in subjects receiving twice-daily dosing of 2.0 g GLY-200 (N = 9) versus those receiving placebo (N = 8).

CONCLUSIONS

GLY-200 is safe and generally well tolerated at doses of ≤2.0 g twice daily. Pharmacodynamic results mimic the biomarker signature observed after Roux-en-Y gastric bypass and duodenal exclusion devices, indicating a pharmacological effect in the proximal small intestine. This study represents the first clinical demonstration that duodenal exclusion can be achieved with an oral drug and supports further development of GLY-200 for the treatment of obesity and/or T2D.

Elucidating complex triplet-state dynamics in the model system isopropylthioxanthone

We introduce techniques for probing the dynamics of triplet states. We employ these tools, along with conventional techniques, to develop a detailed understanding of a complex chemical system: a negative-tone, radical photoresist for multiphoton absorption polymerization in which isopropylthioxanthone (ITX) is the photoinitiator. This work reveals that the same color of light used for the 2-photon excitation of ITX, leading to population of the triplet manifold through intersystem crossing, also depletes this triplet population via linear absorption followed by reverse intersystem crossing (RISC). Using spectroscopic tools and kinetic modeling, we identify the reactive triplet state and a non-reactive reservoir triplet state. We present compelling evidence that the deactivation channel involves RISC from an excited triplet state to a highly vibrationally excited level of the electronic ground state. The work described here offers the enticing possibility of understanding, and ultimately controlling, the photochemistry and photophysics of a broad range of triplet processes.

Abstract CT153: SDX-7320 elicits improvements in tumor-related and metabolic biomarkers: Results of a phase 1 dose-escalation study in patients with advanced refractory or late-stage solid tumors

Background and Rationale: Metabo-oncology is the study of specific tumor types whose growth and/or metastasis is accelerated by metabolic dysfunction, often associated with hyper-adiposity. In this setting the metabolic hormones leptin, adiponectin and insulin are potential mediators. SDX-7320 is a novel methionine aminopeptidase type 2 inhibitor (MetAP2) being developed for use in combination with other anti-cancer agents to treat the metabo-oncology patient population.

Study Design: This first-in-human study used a 3+3 design with dose expansion at the RP2D. Measurements included standard assessments of safety, tolerability, as well as inhibition of MetAP2 in whole blood, plasma levels of protein biomarkers and drug exposure. Tumor response was measured using RECIST v.1.1.

Results: 32 patients with an average of 5.3 prior treatment regimens were dosed. Sub-cutaneous dosing of SDX-7320 began at 1.7 mg/m2 once per week (Q7D, 28 days/cycle) and was escalated to 49 mg/m2. Repeated Q7D administration at 49 mg/m2 resulted in dose-limiting (G3-G4) thrombocytopenia. Expansion at 49 mg/m2 confirmed thrombocytopenia as the dose-limiting toxicity (DLT), reversible upon cessation of dosing. Dose-escalation was re-initiated at 36 mg/m2 every two weeks (Q14D). Repeated dosing at 65 mg/m2 (Q14D) resulted in G3 reversible thrombocytopenia. Expansion at 49 mg/m2 (Q14D) confirmed that this was the maximum tolerated dose (MTD) on a Q14D schedule. No deaths or Grade 5 TEAEs attributable to SDX-7320 were reported. Six patients had a combined total of 9 Grade 3/4 TEAEs considered by the Investigator to be at least possibly SDX-7320-related: thrombocytopenia (4 patients) and single cases of anemia, anorexia, fatigue, QTc prolonged, and vasculitis. Fourteen patients (44% had stable disease &gt2 cycles and three patients had stable disease for ≥6 cycles. Inhibition of MetAP2 in whole blood was 100% at all doses evaluated while the time to reach 100% inhibition was inversely related to dose. When stratified for elevated baseline levels, the following biomarkers declined after initiating SDX-7320 (average of each patient's maximum % change relative to baseline +/- SD): bFGF (-53 +/- 76%), VEGF-C (-35 +/- 39%), and insulin (-55 +/- 30%). Without stratification, leptin levels declined (-51 +/-29%) and levels of adiponectin increased after SDX-7320 (+74 +/- 63% relative to baseline).

Conclusions and Next Steps : SDX-7320 was well-tolerated with prolonged stable disease in an open-label, phase I first-in-human study. Improvements were observed in both tumor-related and metabolic biomarkers. Additional studies of SDX-7320 (in combination with other anti-cancer agents) in patients with solid tumors sensitive to metabolic hormones are scheduled. SDX-7320 is the first novel agent in clinical development to treat the metabo-oncology patient population.

Citation Format: Monica M. Mita, Johanna Bendell, Alain C. Mita, Michael Gordon, Jasgit Sachdev, Bradley J. Carver, James Shanahan, Benjamin Mayes, Kris Awerkamp, David Browning, Neal Salomon, Kimberly Sullivan, Alfred Anderson-Villaluz, Joe Johnson, John S. Petersen, David J. Turnquist, Peter Cornelius. SDX-7320 elicits improvements in tumor-related and metabolic biomarkers: Results of a phase 1 dose-escalation study in patients with advanced refractory or late-stage solid tumors [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT153.

Abstract 4919: Preclinical activity of SDX-7320 in mouse models of obesity and obesity-driven cancer

Cancer patients who are obese face a greater risk of dying from cancer compared to nonobese patients (Calle, 2003). Obesity is believed to contribute to metastasis and progression of cancer via multiple mechanisms: increased secretion of the adipose tissue hormone leptin, decreased secretion of adiponectin, increased production of estrogen in adipose tissue, and elevated insulin (secondary to peripheral insulin resistance) as well as the local effects of inflammatory cytokines (Gucalp, 2016). Small-molecule inhibitors of methionine aminopeptidase type 2 (MetAP2) have previously demonstrated clinical activity in oncology (Kudelka, 1998) as well as obesity/type 2 diabetes (Hughes, 2013; Kim, 2015). However, development of some small-molecule MetAP2 inhibitors has been hampered by CNS side effects (Bhargava, 1999). SDX-7320 is a copolymer-drug conjugate of a novel fumagillin-derived MetAP2 inhibitor (SDX-7539) attached via a cleavable linker to a hydroxypropylmethacrylamide (HPMA) backbone, intended to limit CNS penetration and therefore reduce CNS toxicity. In vitro MetAP2 binding assays showed that SDX-7320 was unable to bind to MetAP2 while SDX-7539 was a potent binder (apparent IC50 = 0.13 nM), indicating that cleavage of SDX-7320 is required for biologic activity. SDX-7539 inhibited proliferation of human umbilical vein endothelial cells (HUVECs) with an apparent IC50 = 0.2 nM. The preclinical efficacy of SDX-7320 was evaluated in mouse models of obesity/insulin resistance and also in syngeneic tumor models coupled with high fat diet-induced obesity (DIO)/metabolic dysfunction. Obesity and insulin resistance were induced in C57Bl/6 mice by feeding them a high-fat diet (HFD) for at least 12 weeks. SDX-7320 was dosed subcutaneously every 4 days (for 28 days) into DIO mice or control mice fed a low-fat diet. SDX-7320 caused significant reduction in body weight and fat mass in obese mice while also reversing insulin resistance relative to controls. In addition, SDX-7320 caused greater reduction in body weight in obese mice relative to lean mice. Circulating levels of leptin and insulin were reduced while levels of adiponectin were increased in response to SDX-7320. In mouse models of obesity-accelerated tumor growth, SDX-7320 was more efficacious in obese relative to lean mice harboring subcutaneous B16F10 melanoma or EO771 mammary gland tumors. These effects occurred without any signs of neurotoxicity. SDX-7320, currently in phase I (solid tumors; all-comers; NCT02743637), is being developed for the treatment of cancers whose progression is accelerated in the setting of obesity and host metabolic dysfunction, termed “metabo-oncology.”

Citation Format: Peter Cornelius, John S. Petersen, Benjamin Mayes, David Turnquist, Kimberly Sullivan, Alfred Anderson-Villaluz, Robert Lutz, Sara Little, Andrew Slee, Bradley J. Carver, James Shanahan. Preclinical activity of SDX-7320 in mouse models of obesity and obesity-driven cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4919.

The influence of feeding crimped kernel maize silage on broiler production, nutrient digestibility and meat quality

Two experiments were carried out in parallel with male Ross 308 broilers over 37 d. An experiment with a total of 736 broilers was performed to study the effect of dietary inclusion of crimped kernel maize silage (CKMS) on broiler production and meat quality. Another study with 32 broilers was carried out from 21 to 25 d to investigate the inclusion of CKMS on nutrient digestibility. In both trials, 4 dietary treatments were used: wheat-based feed (WBF), maize-based feed (MBF), maize-based feed supplemented with 15% CKMS (CKMS-15) and maize-based feed supplemented with 30% CKMS (CKMS-30). Compared with MBF, the dry matter (DM) intakes of broilers receiving CKMS-15 and CKMS-30, respectively, were numerically 7.5 and 6.2% higher and feed conversion ratio 6 and 12% poorer (significant for 30% CKMS), although there were no significant differences in AME content between the three diets. At 37 d, the body weight of birds receiving 15% CKMS was similar to birds fed with MBF. However, the inclusion of 30% CKMS decreased broiler growth. Dietary supplementation with CKMS significantly reduced the apparent digestibility of phosphorus. The fat digestibility was significantly lower for CKMS-30 than for the other three diets. Broiler mortality decreased significantly when CKMS was added to the diet. The consumption of drinking water was significantly lower in all maize-based diets as compared to WBF and was lowest in broilers fed with CKMS-30. An improved litter quality in terms of DM content and a lower frequency of foot pad lesions was observed with broilers supplemented with both dietary levels of CKMS. The addition of CKMS to maize-based diets increased juiciness, tenderness and crumbliness of the meat. In conclusion, the dietary supplementation of 15% CKMS had no negative effect on broiler growth and positively influenced bird welfare in terms of mortality and foot pad health. Therefore, the addition of 15% CKMS to maize-based diets is considered an advantageous feeding strategy in broiler production.

2-Colour photolithography

Photolithography is a crucial technology for both research and industry. The desire to be able to create ever finer features has fuelled a push towards lithographic methods that use electromagnetic radiation or charged particles with the shortest possible wavelength. At the same time, the physics and chemistry involved in employing light or particles with short wavelengths present great challenges. A new class of approaches to photolithography on the nanoscale involves the use of photoresists that can be activated with one colour of visible or near-ultraviolet light and deactivated with a second colour. Such methods hold the promise of attaining lithographic resolution that rivals or even exceeds that currently sought by industry, while at the same time using wavelengths of light that are inexpensive to produce and can be manipulated readily. The physical chemistry of 2-colour photolithography is a rich area of science that is only now beginning to be explored.

Effects of 12 weeks' treatment with a proton pump inhibitor on insulin secretion, glucose metabolism and markers of cardiovascular risk in patients with type 2 diabetes: a randomised double-blind prospective placebo-controlled study

AIMS/HYPOTHESIS

Recent studies suggest that proton pump inhibitor treatment may increase insulin secretion and improve glucose metabolism in type 2 diabetes. In a randomised double-blind prospective placebo-controlled 2 × 2 factorial study, we examined the effect of esomeprazole on insulin secretion, HbA(1c) and cardiovascular risk factors in type 2 diabetes.

METHODS

Forty-one patients with type 2 diabetes using dietary control or oral glucose-lowering treatment were randomised to receive add-on esomeprazole 40 mg (n = 20) or placebo (n = 21) for 12 weeks. Randomisation was carried out prior to inclusion on the basis of a computer-generated random-number list. The allocation sequence was concealed in sealed envelopes from the researcher enrolling and assessing participants. The study was undertaken at Steno Diabetes Center, Gentofte, Denmark. The primary outcome was change in AUC for insulin levels during a meal test. Secondary outcomes were the levels of HbA(1c) and biochemical markers of cardiovascular risk, including lipids, coagulation factors, inflammation markers, markers of endothelial function and 24 h ambulatory BP measurements.

RESULTS

Forty-one participants were analysed. In the esomeprazole-treated group the AUC for insulin did not change (before vs after treatment: 28,049 ± 17,659 vs 27,270 ± 32,004 pmol/l × min (p = 0.838). In the placebo group AUC for insulin decreased from 27,392 ± 14,348 pmol/l × min to 22,938 ± 11,936 pmol/l × min (p = 0.002). Esomeprazole treatment (n = 20) caused a ninefold increase in the AUC for gastrin. HbA(1c) increased from 7.0 ± 0.6% (53 ± 5 mmol/mol) to 7.3 ± 0.8% (56 ± 6 mmol/mol) in the esomeprazole-treated group and from 7.0 ± 0.6% (53 ± 5 mmol/mol) to 7.4 ± 0.8% (57 ± 6 mmol/mol) in the placebo group (n = 21) (p for difference in change >0.05). Except for BP, there were no differences between the groups in the markers of cardiovascular risk (p > 0.05). Monitoring of 24 h ambulatory BP showed a significant decrease in daytime systolic BP, daytime diastolic BP and 24 h diastolic BP in the placebo group (p < 0.05). No change in BP was seen in the patients treated with esomeprazole.

CONCLUSIONS/INTERPRETATION

Treatment with esomeprazole over 12 weeks did not improve insulin secretion, glycaemic control or cardiovascular disease biomarkers in patients with type 2 diabetes.

Relationship between RN(-) genotype and drip loss in meat from Danish pigs

The presence of the RN(-)-gene determined in 72 halothane negative Danish pigs, either by a direct genotyping or the glycolytic potential of the meat, in relation to drip loss, was investigated. The drip loss in the M. longissimus dorsi from RN-carriers (n=26), as determined by genotyping was 9.9% compared to 8.6% in non-carriers (n=46) (P=0.07). When a glycolytic potential of >230 μmol lactate/g meat was used to differentiate between carriers and non carriers of the RN(-)-gene, the drip loss in carriers was 10.6% (n=17) compared to 8.7% in non-carriers (n=55) (P<0.01). These results suggest that the presence of the RN(-)-gene in Danish slaughter pigs only partially explains the large variation in drip loss observed in Danish pork.

Glucagon and a glucagon-GLP-1 dual-agonist increases cardiac performance with different metabolic effects in insulin-resistant hearts

BACKGROUND AND PURPOSE

The prevalence of heart disease continues to rise, particularly in subjects with insulin resistance (IR), and improved therapies for these patients is an important challenge. In this study we evaluated cardiac function and energy metabolism in IR JCR:LA-cp rat hearts before and after treatment with an inotropic compound (glucagon), a glucagon-like peptide-1 (GLP-1) receptor agonist (ZP131) or a glucagon-GLP-1 dual-agonist (ZP2495).

EXPERIMENTAL APPROACH

Hearts from IR and lean JCR:LA rats were isolated and perfused in the working heart mode for measurement of cardiac function and metabolism before and after addition of vehicle, glucagon, ZP131 or ZP2495. Subsequently, cardiac levels of nucleotides and short-chain CoA esters were measured by HPLC.

KEY RESULTS

Hearts from IR rats showed decreased rates of glycolysis and glucose oxidation, plus increased palmitate oxidation rates, although cardiac function and energy state (measured by ATP/AMP ratios) was normal compared with control rats. Glucagon increased glucose oxidation and glycolytic rates in control and IR hearts, but the increase was not enough to avoid AMP and ADP accumulation in IR hearts. ZP131 had no significant metabolic or functional effects in either IR or control hearts. In contrast, ZP2495 increased glucose oxidation and glycolytic rates in IR hearts to a similar extent to that of glucagon but with no concomitant accumulation of AMP or ADP.

CONCLUSION AND IMPLICATIONS

Whereas glucagon compromised the energetic state of IR hearts, glucagon-GLP-1 dual-agonist ZP2495 appeared to preserve it. Therefore, a glucagon-GLP-1 dual-agonist may be beneficial compared with glucagon alone in the treatment of severe heart failure or cardiogenic shock in subjects with IR.

Treatment with a proton pump inhibitor improves glycaemic control in Psammomys obesus, a model of type 2 diabetes

AIMS/HYPOTHESIS

Gastrin has been implicated in islet growth/neogenesis, and proton pump inhibitors (PPIs) have been shown to increase endogenous gastrin levels in animals and humans. Therefore, we investigated the effect of PPIs in a model of type 2 diabetes, Psammomys obesus.

METHODS

P. obesus (morning blood glucose [mBG] 16.9 +/- 0.6 mmol/l) were treated with vehicle or different doses (1-15 mg/kg) of lansoprazole for 17 days.

RESULTS

Treatment with lansoprazole resulted in up to ninefold dose-dependent increases in endogenous gastrin levels (p < 0.05 for 10 mg/kg lansoprazole vs vehicle). There was a significant reduction in mBG levels in all animals in the high-dose lansoprazole groups during the 17 day treatment period, whereas there was no significant improvement in mBG in animals in the vehicle groups. The mBG at end of study was 18.2 +/- 2.1, 8.7 +/- 2.2 (p < 0.01), and 6.1 +/- 2.3 (p < 0.001) mmol/l for vehicle and lansoprazole 10 and 15 mg/kg, respectively. The animals treated with 15 mg/kg lansoprazole, compared with vehicle, had a 2.3-fold increase in the intensity of insulin staining in beta cells (p=0.0002) and 50% higher beta cell mass (p=0.04).

CONCLUSIONS/INTERPRETATIONS

The PPI lansoprazole had significant glucose-lowering effects in an animal model of type 2 diabetes, an effect that is most likely mediated through an increase in endogenous gastrin levels.

Advances in pemphigus research, signaling, and acantholysis

Pemphigus is a family of human autoimmune blistering diseases in which pathogenic autoantibodies induce blistering in skin and mucosa. The mechanisms by which pemphigus autoantibodies induce disease in the skin is under active investigation. A large number of cellular events induced in the target keratinocytes by pemphigus IgG have been described and suggest that pemphigus IgG binding to desmogleins trigger a complicated cascade of intracellular signaling and regulatory events. Targeting these intracellular events may prove useful therapeutically.

Coupling of oral human or porcine insulin to the B subunit of cholera toxin (CTB) overcomes critical antigenic differences for prevention of type I diabetes

Our earlier investigations have demonstrated a critical difference in the efficacy of orally administered porcine compared to human or mouse insulin (no effect) in preventing type I diabetes in two distinct experimental models. Based on these findings one has to assume that certain insulins might not be suitable for the induction of oral 'tolerance'/bystander suppression, which might be one cause for recent failures in human oral antigen trials. Here we demonstrate that coupling to the non-toxic subunit of cholera toxin (CTB) can abolish these differences in efficacy between human and porcine insulin. As expected, an added benefit was the much smaller oral antigen dose required to induce CD4+ insulin-B specific regulatory cells that bystander-suppress autoaggressive responses. Mechanistically we found that uptake or transport of insulin-CTB conjugates in the gut occurs at least partially via binding to GM-1, which would explain the enhanced clinical efficacy. Both B chains bound well to major histocompatibility complex (MHC) class II, indicating comparable immunological potential once uptake and processing has occurred. Thus, our findings delineate a pathway to overcome issues in oral antigen choice for prevention of type I diabetes.

The cholera toxin B subunit directly costimulates antigen-primed CD4+ T cells ex vivo

The nontoxic B subunit of cholera toxin (CTB) has been used as an adjuvant in experimental systems of mucosal vaccination. However, the mechanisms behind its adjuvant effects remain unclear. Here, we have used an ex vivo system to elucidate these mechanisms in antigen-specific T cells. Using splenocytes from keyhole limpet haemocyanin (KLH)-immunized mice, initial experiments showed that recombinant CTB (rCTB) did not affect the KLH-specific proliferation of splenocytes isolated from mice immunized 2 weeks earlier. However, rCTB strongly enhanced the KLH-specific proliferation of splenocytes from mice immunized with KLH 4 weeks prior. This adjuvant effect was dose-dependent, with maximum at 30-300 ng/ml rCTB. At higher doses of CTB this effect declined because of the induction of apoptosis. Using antibody depletion and coculture systems, we show that rCTB directly costimulates KLH-specific CD4+ and CD8+ T-cell proliferation but not B cells. Enzyme-linked immunospot (ELISPOT) assays revealed that rCTB also enhanced the KLH-specific CD4+ T-cell-mediated production of interleukin-2 (IL-2), IL-4 and interferon-gamma(IFN-gamma) by four to fivefold. Characterizing the adjuvant effect of rCTB in vivo confirmed the results above, i.e. rCTB mediated a twofold increase in the ex vivo T-cell response when used as a classical adjuvant in a secondary, but not in a primary KLH-immunization regimen. Together these data show that rCTB can act as a strong adjuvant, by directly costimulating antigen-primed CD4+ and CD8+ T cell in a dose-dependent manner. This new insight might be valuable in the future rational design of bacterial toxin-based vaccines.

The cholera toxin B subunit is a mucosal adjuvant for oral tolerance induction in type 1 diabetes

When conjugated to various proteins, the nontoxic B-chain of cholera toxin (CTB) significantly increases the ability of these proteins to induce immunological tolerance after oral administration. Here, we investigated if a nonconjugated form of CTB enhances the induction of immune tolerance after oral insulin administration. Induction of immunological tolerance was studied after oral administration of insulin preparations in three mouse models; an insulin/ovalbumin coimmunization model, a model of virus-induced diabetes in transgenic RIP-LCMV-NP mice and in nonobese diabetic (NOD) mice serving as a model of spontaneous diabetes. In the immunization model, we demonstrate that mixing with CTB increases the tolerogenic potential of insulin, approximately 10 fold. Titration of the CTB concentration in this system revealed that an insulin : CTB ratio of 100 : 1 was optimal for the induction of bystander suppression. Further studies revealed that this insulin : CTB ratio also was optimal for the prevention of diabetes in a virus-induced, transgenic diabetes model. In addition, the administration of this optimal insulin-CTB preparation significantly prevented the onset of diabetes in old NOD mice with established islet infiltration. The data presented here demonstrate that CTB, even in its unconjugated form, functions as a mucosal adjuvant, increasing the specific tolerogenic effect of oral insulin.

Sevelamer, a phosphate-binding polymer, is a non-absorbed compound

OBJECTIVE

To examine the absorption, distribution and excretion of sevelamer hydrochloride in rats and humans.

PARTICIPANTS

Twelve male Sprague-Dawley rats were used in the animal study, and twenty human volunteers participated in the clinical trial.

METHODS

In the animal study, six rats received a single oral dose of [(3)H]sevelamer and six rats were pretreated with unlabelled sevelamer in the diet for 28 days followed by a single dose of [(3)H]sevelamer on day 29. Total urine and faeces were collected at intervals up to 72 hours post dose, and tissues were obtained at the time of sacrifice. In the clinical trial, subjects received a single oral dose of [(14)C]sevelamer following 28 days of pretreatment with unlabelled sevelamer. Blood, urine and faeces samples were collected at intervals up to 96 hours.

RESULTS

In the rat study, no significant urinary excretion of radioactivity was observed. The average recovery of radioactivity in the faeces was 98% in the single-dose group and greater than 100% in the group pretreated with unlabelled sevelamer for 28 days. A total of less than 0.1% of the dose was found in the tissues. In the human study, no detectable amount of (14)C was found in the blood of any subject at any time. The majority of subjects had no detectable amounts of (14)C recovered in the urine. In subjects where (14)C was recovered in the urine, less than 0.02% was detected, a level equivalent to the free (14)C detected in the [(14)C]sevelamer preparation. On average, greater than 99% of the administered dose was recovered in the faeces of the subjects.

CONCLUSION

These studies demonstrate that sevelamer is a non-absorbed compound.

Determination of the binding parameter constants of Renagel capsules and tablets utilizing the Langmuir approximation at various pH by ion chromatography

Sevelamer hydrochloride is a cross-linked polymeric amine; it is the active ingredient in Renagel capsules and tablets. Sevelamer hydrochloride is indicated for the control of hyperphosphatemia in patients with end-stage renal disease. The binding parameter constants of sevelamer hydrochloride were determined using the Langmuir approximation for three different dosage forms at pH 4.0, 5.5 and 7.0. The three dosage forms were Renagel 403 mg capsules, Renagel 400 mg tablets and Renagel 800 mg tablets. The results demonstrate the equivalency of all three dosage forms at each pH. The results also demonstrate a shift in the binding mechanism from pH 4.0 to 7.0.

Intracerebroventricular metformin attenuates salt-induced hypertension in spontaneously hypertensive rats

The aim of this study was to examine the effects of long-term continuous intracerebroventricular (icv) infusion of metformin on blood pressure (BP) in spontaneously hypertensive rats (SHR). To accelerate the development of hypertension, SHR were fed a 8% NaCl diet during the 3-week study period. Metformin was given in the following doses: 0 (isotonic saline; n = 7), 25 (n = 8), 50 (n = 6), 100 (n = 6), and 200 microg/day icv (n = 5). Mean arterial pressure (MAP) and heart rate (HR) were measured by radiotelemetry, and as a measure of the contribution of sympathetic nerve activity to BP, the decrease in MAP in response to ganglionic blockade with hexamethonium, 30 mg/kg iv, was determined once weekly. In vehicle treated rats, MAP increased by 27+/-4 mm Hg, whereas in rats treated with a low dose of metformin (25 microg/day), MAP increased only by 7+/-3 mm Hg (P < .01). The hypotensive response to hexamethonium was attenuated by all doses of metformin suggesting that chronic icv metformin decreased central sympathetic outflow. The highest doses of metformin (100 and 200 microg/day) also prevented development of hypertension, but these doses were highly neurotoxic as demonstrated by histologic evaluation post mortem. Fast-Fourier transformation of MAP revealed increased variability within the 0.15 to 0.6 Hz frequency range in rats treated with neurotoxic doses of metformin, suggesting impaired sympathetic control of BP in these animals. In conclusion, long-term icv infusion with apparently nontoxic doses of metformin attenuates hypertension and decreases the hypotensive responses to ganglionic blockade in SHR, suggesting a centrally elicited sympathoinhibitory action.

Low prevalence of GAD and IA2 antibodies in schoolchildren from a village in the southwestern section of the Netherlands

Glutamic acid decarboxylase (GAD) and insulinoma antigen 2 (IA2) antibodies are increasingly used as a tool to predict type I diabetes in children and as a differential diagnostic tool to distinguish type I and type II diabetes in adults. However, the background frequency of these antibodies in the general population has not been extensively studied and may differ between countries. The current study aims to establish the frequency of GAD and IA2 antibodies in an unselected population of schoolchildren and confirm the previously reported low prevalence of islet cell antibodies (ICA) in the general Dutch population. The study population consisted of 1403 unselected schoolchildren. All children were tested for GAD antibodies, and 1085 children were analyzed for IA2 antibodies by radiobinding assay. Development of diabetes was recorded during a 7-year follow-up. Five children (0.4%) were positive for GAD antibodies, one child (0.1%) was positive for IA2 antibodies. Two children developed diabetes during follow-up, one was positive for GAD antibodies only, the second was positive for both GAD and IA2 antibodies. The frequency of GAD and IA2 antibodies in the southwestern part of The Netherlands is low. This observation is in concordance with earlier studies on ICA in Dutch schoolchildren. For future diabetes prediction and intervention trials it is important to establish the background frequencies and predictive power of antibody screening in different populations.

Brain angiotensin receptors and sympathoadrenal regulation during insulin-induced hypoglycemia

Simultaneous blockade of systemic AT1 and AT2 receptors or converting enzyme inhibition (CEI) attenuates the hypoglycemia-induced reflex increase of epinephrine (Epi). To examine the role of brain AT1 and AT2 receptors in the reflex regulation of Epi release, we measured catecholamines, hemodynamics, and renin during insulin-induced hypoglycemia in conscious rats pretreated intracerebroventricularly with losartan, PD-123319, losartan and PD-123319, or vehicle. Epi and norepinephrine (NE) increased 60-and 3-fold, respectively. However, the gain of the reflex increase in plasma Epi (Deltaplasma Epi/Deltaplasma glucose) and the overall Epi and NE responses were similar in all groups. The ensuing blood pressure response was similar between groups, but the corresponding bradycardia was augmented after PD-123319 (P < 0.05 vs. vehicle) or combined losartan and PD-123319 (P < 0.01 vs. vehicle). The findings indicate 1) brain angiotensin receptors are not essential for the reflex regulation of Epi release during hypoglycemia and 2) the gain of baroreceptor-mediated bradycardia is increased by blockade of brain AT2 receptors in this model.

Muscle glycogen stores and meat quality as affected by strategic finishing feeding of slaughter pigs

The aim of the present study was to investigate whether muscle glycogen stores in slaughter pigs could be decreased through strategic finishing feeding before slaughter. Moreover, preliminary meat quality traits were measured to see whether such a regulation of muscle glycogen stores affected ultimate pH, color, and tenderness in the meat. The strategic finishing feeding was carried out the last 3 wk prior to slaughter. Seven experimental groups with eight animals per group were fed diets low in digestible carbohydrates. A control group with four animals was fed a traditional grower-finishing diet. The muscle glycogen stores were reduced in longissimus muscle (LM) 11 to 26% at the time of slaughter in pigs that were fed the experimental diets compared with the control group. Meat quality measured as ultimate pH and color on LM muscle in half the pigs 24 h postmortem showed that ultimate pH in LM was not affected by the reduction in glycogen stores in the muscles from pigs fed any of the experimental diets. However, the meat from pigs fed the experimental diets was darker than the meat from pigs that were fed the control diet with two of the experimental diets, resulting in significantly lower L* values. Activities of key enzymes in the glycolytic pathway, glycogen phoshorylase a and b, phosphofructokinase, and the fatty acid oxidative pathway, beta-hydrozyacyl-CoA-dehydrogenase, were not affected by the strategic feeding. In contrast, the activity of the proteolytic enzyme calpain as well as its inhibitor calpastatin was influenced by the strategic feeding. Lower activity of mu-calpain and greater activity of calpastatin in the muscle samples from the strategically fed pigs indicate a lesser muscle protein degradation in the muscles compared with muscles of control animals. The present study showed that the muscle glycogen stores in slaughter pigs can be reduced at the time of slaughter through strategic finishing feeding with diets low in digestible carbohydrate without compromising growth rate.

Increased natriuretic efficiency of furosemide in rats with carbon tetrachloride-induced cirrhosis

The authors examined the natriuretic efficiency of furosemide in rats with cirrhosis induced by carbon tetrachloride (CCl(4)). Rats were treated for 17 weeks with intraperitoneal injections of CCl(4) in groundnut oil twice a week throughout the study. Control rats were treated with vehicle (groundnut oil). Studies in metabolic cages showed that sodium retention was present from week 14. Renal clearance experiments were performed in chronically, instrumented conscious rats at the end of week 14 and at the termination of the study (end week 16) when ascites and hyponatremia were present. After 14 weeks, cirrhotic rats had sodium retention along with increased renal plasma flow, normal GFR, normal renal lithium handling, and a significantly increased diuretic (+41% vs. control) and natriuretic (+56% vs. control) response to a test dose furosemide (7.5 mg/kg b.w., intravenously). The natriuretic efficiency of furosemide, i.e., the natriuresis expressed relative to the furosemide excretion rate (triangle upU(Na)V/U(FUR)V) was increased by 51% versus control. After 17 weeks, ascites and hyponatremia had developed, and significant decreases in renal plasma flow (-33%), GFR (-30%), and fractional lithium excretion (-44%) were observed. At this stage urinary recovery of furosemide was significantly decreased and the diuretic (-27% vs. Control) and natriuretic (-38% vs. control) responses to furosemide were significantly impaired. However, the increased natriuretic efficiency of furosemide was still present (+34% vs. control). Together these results suggest that increased sodium reabsorption in the thick ascending limb of Henle's loop is involved in the renal sodium retention in cirrhosis in rats that eventually results in decompensation with the formation of ascites.

Albuminuria in ischemic heart disease

Proteinuria associated with acute heart disease was studied prospectively in 160 patients admitted to the coronary care unit with suspected AMI. Series 1 comprised 150 patients, divided into the following groups: AMI, 27 UAP, 43 AP, 22 NIP and 18 excluded. Albumin and creatinine were measured in the first urine passed after admission (sample 1) and the first morning urine the following 2 days (samples 2 and 3). The ACR was significantly higher in the AMI and UAP groups than in the other patient groups (p < 0.0001). There was no significant difference of ACR between the AMI and UAP in sample 1 (p = 0.31). In the AMI, UAP and AP groups ACR was significantly higher in sample 1 than in samples 2 and 3 (p < 0.005). In the NIP group there were no significant differences between sample 1 versus samples 2 and 3 (p = 0.06). Series 2 comprised 10 patients: 8 AMI, 1 UAP and 1 AMYO. ACR were measured in all specimens voided during the period of observation. ACR can oscillate within hours between normal concentrations and concentrations well into or above the microalbuminuric range. We propose the term episodic albuminuria for this reversible, switch-like change in renal function. The albuminuric episodes lasted 90-600 minutes. Maximum values for ACR were between 133-790 mumol/mol or 78-466 mg/g. In healthy, resting individuals ACR is < 50 mumol/mol (< 30 mg/g). The rapid changes in glomerular permeability may reflect systemic changes in endothelial permeability in the affected individuals. We speculate that atrial natriuretic peptide (ANP) may be a mediator of this type of albuminuria.

Decreased vasopressin-mediated renal water reabsorption in rats with chronic aldosterone-receptor blockade

Previous studies have suggested that mineralocorticoids are needed for a normal action of vasopressin on collecting duct osmotic water permeability. However, the mechanisms behind this are unknown. To investigate if aldosterone-receptor blockade influences vasopressin type 2 receptor (V(2))-mediated renal water reabsorption and the renal expression of the vasopressin-regulated water channel aquaporin-2 (AQP2), rats were treated with the aldosterone-receptor antagonist canrenoate (20 mg/day iv) for 4 wk. Daily urine flow was increased significantly by 44%, and urine osmolality was decreased by 27% in canrenoate-treated rats. Acute V(2)-receptor blockade (OPC-31260, 800 microgram. kg(-1). h(-1)) was performed under conditions in which volume depletion was prevented. In control rats, OPC-31260 induced a significant increase in urine flow rate (V, +25%) and free water clearance (C(H(2)O), -29%). In canrenoate-treated rats, the effect of OPC-31260 was significantly reduced, and semiquantiative immunoblotting demonstrated a significant reduction (45%) in AQP2 expression. Because rats with common bile duct ligation (CBL) have a reduced vasopressin-mediated water reabsorption compared with normal rats (V: -24%; C(H(2)O): -28%, and 86% downregulation of AQP2), the effect of canrenoate combined with OPC-31260 was tested. Canrenoate treatment of CBL rats significantly increased daily urine flow, decreased urine osmolality, and impaired the aquaretic response to OPC-31260 (V: -23%; C(H(2)O): -31%) with maintained suppression of the renal AQP2 expression. Thus canrenoate treatment of normal and CBL rats showed 1) increased urine production, 2) reduced aquaretic effect of acute V(2)-receptor blockade, and 3) a marked reduction in AQP2 expression. This strongly supports the view that aldosterone plays a significant role for vasopressin-mediated water reabsorption.

Effects of chronic octreotide treatment on renal changes during cirrhosis in rats

We examined the effect of a new long-acting release formula (LAR) of the somatostatin analogue, octreotide, on development of sodium retention and functional and structural changes in the thick ascending limb of Henle's loop (TAL) in rats with cirrhosis induced by common bile duct ligation (CBL). CBL and sham-operated control rats were treated with octreotide-LAR (10 mg/kg body weight subcutaneously, as a single dose) or vehicle at the time of CBL or sham-CBL. The rats were instrumented with chronic catheters, and sodium balance and renal function were examined 4 weeks after CBL or sham operation. Octreotide-LAR treatment significantly inhibited sodium retention in CBL rats and prevented renal vasodilatation without changes in glomerular filtration rate (GFR). The natriuretic response to a test dose of furosemide (7.5 mg/kg body weight intravenously) was significantly increased in CBL rats, and when expressed in terms of natriuretic efficiency (mmol Na/mg furosemide in urine), the natriuretic response was increased by 57% relative to sham-operated controls. Stereological examination of kidneys demonstrated a 53% increase in the volume of the inner stripe of the outer medulla and a 108% increase in the volume of TAL epithelium in cirrhotic rats relative to controls. The increased natriuretic efficiency of furosemide as well as the hypertrophy of the inner stripe and the TAL in this renal zone were absent in CBL rats treated with octreotide-LAR. These results suggest that octreotide-LAR treatment inhibits sodium retention in cirrhotic rats, partly by inhibition of increased furosemide-sensitive sodium reabsorption in the TAL.

Progression to type 1 diabetes is associated with a change in the immunoglobulin isotype profile of autoantibodies to glutamic acid decarboxylase (GAD65). Childhood Diabetes in Finland Study Group

To investigate whether type 1 diabetes in man is associated with a preferential Th1/Th2 response, and whether autoantibodies to one of the main autoantigens would reflect such a response, we characterized the immunoglobulin isotype profile to the 65-kDa isoform of glutamic acid decarboxylase (GAD65) in siblings to IDDM patients. Samples obtained from affected subjects before and at clinical onset of IDDM, from unaffected individuals at high risk and at low risk and from healthy controls were studied. The immunoglobulin isotype profile in the siblings at low risk reflected a more immature, i.e., IgM and Th2 like, i.e., IgE response compared to the progressors and siblings at high risk, with significantly higher median levels of IgM and IgE. The rank order of anti-GAD65 immunoglobulin isotypes was similar in the siblings before and at clinical onset of IDDM, IgG1 > IgG4 > IgM > IgE > IgA > IgG3 > IgG2, but markedly different in the individuals at low risk, IgG1 > IgM > IgE > IgG4 > IgG3 > IgA > IgG2. Based on these observations, we suggest that progression to clinical onset of IDDM is associated with a maturation and a decrease in the Th2 immune response against GAD65; findings which could have implications for future intervention and prediction strategies.

Aldosterone receptor blockade inhibits increased furosemide-sensitive sodium reabsorption in rats with liver cirrhosis

We examined the role of chronic aldosterone receptor blockade on the altered furosemide-sensitive sodium reabsorption in rats with liver cirrhosis induced by common bile duct ligation. CBL and sham-operated control animals were treated with the aldosterone receptor antagonist canrenoate (20 mg/day i.v.) for 4 weeks. Untreated CBL and sham-CBL served as control groups. The plasma concentration of aldosterone was within the normal range in all groups. Sodium balance studies showed that aldosterone receptor blockade prevented sodium retention in cirrhotic rats. Clearance studies showed that the glomerular filtration rate was unchanged, whereas the renal plasma flow was increased in CBL rats. A test dose of furosemide (7.5 mg/kg b.wt. i.v.) produced significantly greater diuretic (+59%) and natriuretic (+56%) responses in CBL rats than in sham-operated controls. The urinary furosemide excretion rate (UFURV) reflects delivery of furosemide to the thick ascending limb. When the natriuresis was expressed relative to UFURV (i.e., the natriuretic efficiency), we found that natriuretic efficiency of furosemide was significantly increased in untreated CBL rats (+59%). However, the natriuretic efficiency of furosemide was normalized in CBL rats treated with canrenoate. The urinary excretion of furosemide was unchanged in untreated CBL rats, but it was significantly increased in cirrhotic rats treated with canrenoate (+43%). This suggests that in CBL rats, chronic canrenoate treatment increases the renal elimination of furosemide as a consequence of reduced metabolism. These data suggest that chronic aldosterone receptor blockade with canrenoate prevents sodium retention in cirrhotic rats partly by inhibition of increased sodium reabsorption in the thick ascending limb.

Immunization of diabetes-prone or non-diabetes-prone mice with GAD65 does not induce diabetes or islet cell pathology

Glutamic acid decarboxylase autoimmunity was investigated by immunizing female BALB/c, C57B1/6, National Marine Research Institute (NMRI) and non-obese diabetic (NOD) mice once or twice with glumatic acid decarboxylase, GAD65, bovine serum albumin, or phosphate-buffered saline in incomplete Freunds adjuvant, or not treating. Mice immunized with GAD65, showed splinic T-cell reactivity to GAD 65 in vitro assessed by cytokine secretion. However untreated NOD mice did not. NOD mice showed a vigorous IFN-gamma response after one immunization, whereas NMRI mice showed a lower response. IL-4 and IL-10 were only detected after two immunizations with higher levels in BALB/c, NMRI and NOD mice, compared to C57B1/6 mice. High levels of GAD65 antibodies were detected in all mice immunized with GAD65, though lower levels were found in C57B1/6 mice. Histological analysis of pancreata revealed that no control mice, regardless of treatment, had mononuclear cell infiltration in the islets. In NOD mice, peri-insulitis was detected in all groups, but less so in GAD65 and bovine serum albumin (BSA) immunized animals. These data demonstrate that NOD mice respond more vigorously to immunization with GAD65 than non-diabetic mice strains. Furthermore, immunization with GAD65 is not sufficient to provoke onset of diabetes in NOD mice or induce islet cell pathology in non-diabetes prone mice.

Decreased vasopressin-mediated renal water reabsorption in rats with compensated liver cirrhosis

Experiments were performed to investigate vasopressin type 2 receptor (V2)-mediated renal water reabsorption and the renal expression of the vasopressin-regulated water channel aquaporin-2 (AQP-2) in cirrhotic rats with sodium retention but without ascites. In addition, the expression of the furosemide-sensitive type 1 Na-K-2Cl cotransporter (BSC-1) and the natriuretic response to an intravenous test dose furosemide (7.5 mg/kg) during acute V2-receptor blockade was measured. Acute V2-receptor blockade with the selective nonpeptide antagonist OPC-31260 (800 microg . kg-1 . h-1) was performed during conditions in which volume depletion was prevented by computer-driven, servo-controlled intravenous volume replacement with 150 mM glucose. OPC-31260 produced a significantly smaller increase in urine flow rate (-26%) and free water clearance (-18%) in cirrhotic rats than in control rats. The natriuretic response to an intravenous test dose furosemide (7.5 mg/kg) was significantly increased in cirrhotic rats (+52%), but pretreatment with OPC-31260 did not affect the natriuretic response to furosemide in neither cirrhotic nor in control rats. Semiquantitative immunoblotting showed a significant downregulation of AQP-2 in the renal cortex (-72%) and in the outer medulla (-44%). The relative expression of BSC-1 in the outer medulla was unchanged in cirrhotic rats. The corticopapillary gradient of Na was significantly increased in cirrhotic rats. Since daily urine flow rate was similar in cirrhotic and sham-operated rats, we suggest that non-vasopressin-mediated water reabsorption is increased in cirrhotic rats probably as a result of an increased corticomedullary gradient due to exaggerated NaCl reabsorption in the thick ascending limb of Henle's loop.

Regulation of GAD expression in rat pancreatic islets and brain by gamma-vinyl-GABA and glucose

Glutamic acid decarboxylase (GAD) is an important autoantigen in insulin-dependent diabetes mellitus (IDDM), but little is known about its regulation and function in islet cells. We investigated the effects of the GABA-transaminase inhibitor gamma-vinyl-GABA (GVG) on GAD expression in rat islets and brain in vitro and in vivo. In islets incubated in high glucose culture medium there was an increase in GAD activity, GAD65 and GAD67 protein levels compared to low-glucose conditions; however, even in high glucose, GVG still significantly suppressed GAD activity and GAD67 expression. Our observations suggest that glucose and GVG act on GAD in islets through different mechanisms. Quantitative immunohistochemistry of pancreatic sections from rats treated with GVG in vivo using novel monoclonal antibodies specific for GAD65 and GAD67, showed a decrease in GAD67 expression (p < 0.005) relative to untreated rats. The effects of GVG on rat pancreatic islets were very similar to those observed in brain of rats treated with GVG in vivo. In homogenates of cerebral tissue from GVG treated rats containing both membrane-bound and soluble protein GAD67 levels were significantly decreased while GAD65 levels were not significantly changed compared to untreated rats. In contrast, in homogenates of cerebral tissues containing only soluble cytosolic protein, GVG-treatment was also significantly found to decrease GAD65 levels. Taken together, these results suggest that GVG potentially could be of use to decrease GAD expression in islet cells and consequently to deviate/inhibit the autoimmune response against the beta cells seen in IDDM.

[Teratogenic effects of ACE-inhibitors and angiotensin II receptor antagonists]

Since the introduction of angiotensin converting enzyme-inhibitors (ACE-inhibitors) in the 1980's, more than 50 cases of foetotoxic effects ascribed to intrauterine exposure to inhibitors have been published. Among the most commonly reported effects are: Hypotension, renal dysplasia, anuria/oliguria, oligohydramios, intrauterine growth retardation, pulmonary hypoplasia, unclosed ductus arteriosus, incomplete ossification of the skull, intrauterine og neonatal death. Recent animal studies have confirmed that intrauterine or neonatal exposure to ACE-inhibitors or the AT1-receptor antagonist losartan can cause death and serious, irreversible organ damage. These effects are similar to the complications previously reported in humans. Animal studies suggest that the foetotoxic actions are most common after exposure during the last trimester. However, due to the severity of these complications, the use of ACE-inhibitors and AT1-receptor antagonists should be avoided throughout pregnancy and in women who are breast feeding.

Effects of occlusive and conventional gauze dressings on incisional healing after abdominal operations

OBJECTIVE

To compare the effect of occlusive (Comfeel) and conventional (Mepore) dressings on the healing of incisional wounds after abdominal operations.

DESIGN

Prospective randomised study.

SETTING

Laboratory and teaching hospital, Denmark.

SUBJECTS

73 patients who underwent clean operations requiring incisions longer than 5 cm between August 1993 and August 1995 were randomised to have their wounds dressed with either Comfeel or Mepore.

INTERVENTIONS

Comfeel was left on until the sutures were removed, and Mepore was removed 2 days postoperatively.

MAIN OUTCOME MEASURES

Infection, adherence, leakage, and cosmetic appearance three months later.

RESULTS

36 patients were randomised to have Comfeel and 37 to have Mepore. 29 patients were withdrawn from the study (20 having Mepore and 9 having Comfeel) leaving 26, and 17 for analysis, respectively. Wound infections developed in 1 patient in the Comfeel group and 5 in the Mepores group (p = 0.2). There were no differences between the groups regarding the need for dressings to be changed, the incidence of leakage, or loosening of the dressing from the skin. Comfeel adhered securely to the skin and remained more or less transparent until sutures were removed. It remained totally transparent in 23 (64%), and no dressing became totally opaque. There were no differences in cosmetic appearance after three months. We had the impression that patients who had Comfeel were more comfortable and found it easier to mobilise and carry out their daily activities.

CONCLUSION

Occlusive dressings stay in place and stay transparent, and do not increase the risk of wound infection. They may even be more comfortable. they are a reasonable alternative to conventional dressings.

Prediction of insulin-dependent diabetes mellitus in siblings of children with diabetes. A population-based study. The Childhood Diabetes in Finland Study Group

An unselected population of 755 siblings of children with insulin-dependent diabetes mellitus (IDDM) was studied to evaluate the predictive characteristics of islet cell antibodies (ICA), antibodies to the IA-2 protein (IA-2A), antibodies to the 65-kD isoform of glutamic acid decarboxylase (GADA), insulin autoantibodies (IAA), and combinations of these markers. We also evaluated whether the histochemical ICA test could be replaced by the combined detection of other markers. 32 siblings progressed to IDDM within 7.7 yr of the initial sample taken at or close to the diagnosis of the index case (median follow-up, 9.1 yr). The positive predictive values of ICA, IA-2A, GADA, and IAA were 43, 55, 42, and 29%, and their sensitivities 81, 69, 69, and 25%, respectively. In contrast to the other three antibody specificities, GADA levels were not related to the risk for IDDM. The risk for IDDM in siblings with four, three, two, one, or no antibodies was 40, 70, 25, 2, and 0.8%, respectively. Combined screening for IA-2A and GADA identified 70% of all ICA-positive siblings, and all of the ICA-positive progressors were also positive for at least one of the three other markers. The sensitivity of the combined analysis of IA-2A and GADA was 81%, and the positive predictive value was 41%. In conclusion, combined screening for IA-2A and GADA may replace the ICA assay, giving comparable sensitivity, specificity, and positive predictive value. Accurate assessment of the risk for IDDM in siblings is complicated, as not even all those with four antibody specificities contract the disease, and some with only one or no antibodies initially will progress to IDDM.

AT1 and AT2 receptor blockade and epinephrine release during insulin-induced hypoglycemia

Angiotensin II facilitates epinephrine release during insulin-induced hypoglycemia, and this effect appears to be independent of type 1 angiotensin II (AT1) receptors in man. In the present study, we hypothesized that the action of angiotensin II on adrenomedullary epinephrine release is mediated by an AT2 receptor-dependent mechanism. In conscious chronically instrumented rats, we measured plasma concentrations of catecholamines during acute insulin-induced hypoglycemia in groups of rats pretreated with the AT1 receptor antagonist losartan (10 mg/kg i.v.), the AT2 receptor antagonist PD123319 (30 mg/kg i.v.), combined losartan + PD123319, the converting enzyme inhibitor enalapril (1 mg/kg i.v.), or vehicle. In vehicle-treated rats, the area under the curve for changes in plasma epinephrine concentration [AUC(plasma epinephrine)] during insulin-induced hypoglycemia was 111+/-8 nmolXh/L (+/-SEM). Pretreatment with losartan alone did not affect AUC(plasma epinephrine) (113+/-17 nmol x h/L), while pretreatment with PD123319 tended to reduce the response (87+/-10 nmol x h/L; P=.08 versus vehicle). However, AUC(plasma epinephrine) was significantly reduced in rats that were pretreated with combined losartan + PD123319 (68+/-5 nmol x h/L; P<.001 versus vehicle) or enalapril: 86+/-10 nmol x h/L (P<.05 versus vehicle). Thus, combined treatment with losartan + PD 123319 proved more effective in attenuating the reflex increase in plasma epinephrine concentration during hypoglycemia than either of the two AT receptor antagonists given alone. We speculate that angiotensin II through binding to both receptor subtypes facilitates the sympathoadrenal reflex response by actions at several anatomical levels of the neural pathways involved in the sympathoadrenal reflex response elicited during insulin-induced hypoglycemia.

Influence of renal nerves and sodium balance on the acute antidiuretic effect of bendroflumethiazide in rats with diabetes insipidus

To examine the role of the renal nerves and sodium depletion for the acute antidiuretic response to bendroflumethiazide (BFTZ; 25 microg/hr) in rats with diabetes insipidus (DI), renal clearance experiments were performed in the following groups of conscious, chronically instrumented male Brattleboro rats with vasopressin-deficient DI: Control (n = 7), BFTZ (n = 9), BFTZ + sodium replacement (n = 7) and BFTZ + chronic bilateral renal denervation (n = 6). Urine flow rate and urinary sodium concentration were measured drop-by-drop with a sodium-sensitive electrode and by collection of urine in vials placed on an electronic balance. This allowed computer driven, servo-controlled, independent i.v. replacement of sodium and fluid losses, respectively. Mean arterial pressure, glomerular filtration rate (GFR) and proximal tubular water and sodium handling, assessed by lithium clearance (C(Li)), were stable in the control group. BFTZ produced a marked antidiuretic response (deltaV = -79%; deltaUrine osmolality = +218%) associated with decreases in GFR (-28%), C(Li) (-62%), free water clearance (-100%) and plasma Na (-5 mM). Fractional water reabsorption was increased by 19% in the proximal tubules and by 7% in segments beyond. Sodium replacement did not modify the fall in GFR or the antidiuresis, but partly prevented the increase in fractional proximal water reabsorption. Bilateral renal denervation did not affect the response to BFTZ. We conclude that the acute antidiuretic effect of BFTZ is independent of sodium balance and renal nerve activity and is elicited by a reduction in GFR accompanied by an increase in fractional water reabsorption in the proximal tubules and in the distal nephron.