Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Differences in residual volume above different tracheostomy tube cuffs depending on tube structure, tube tilt angle, and liquid viscosity

INTRODUCTION

Proper management of aspirated material above the tracheostomy tube cuff is crucial to prevent complications, such as aspiration pneumonia. This study aimed to thoroughly examine the effects of aspirated liquid viscosity, suction port positioning, and tube tilt angle on residual volume above the cuff (RVAC).

METHODS

Five types of tracheostomy tubes (approximately 9 mm outer diameter) were placed through a transparent cylinder with an inner diameter of 18 mm. The cuff was inflated to completely seal the interior of the cylinder. Four liquids with different viscosities were poured onto the cuff, and the liquid above the cuff was suctioned from the side port. The cylinder was angled at 90° and 20°, and each test was performed thrice to determine the average RVAC.

RESULTS

After side-port suctioning, some liquid residue was observed on the cuff of all tracheostomy tubes. The RVAC increased with higher liquid viscosity. The tubes with a longer distance from the suction port opening to the cuff top exhibited more RVAC. Moreover, the RVAC was almost the same regardless of the cylinder angle for tubes with a suction port on the lateral side. However, tubes with backside ports showed a decreased RVAC with cylinder tilt.

CONCLUSIONS

This study underscores the persistence of residual material on cuffed tracheostomy tubes even with regular subglottic secretion drainage. This emphasizes the need for specialized tracheostomy tube development aimed at reducing post-suction RVAC. Improved designs can potentially minimize complications associated with residue accumulation.

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

BACKGROUND

The EMPA-KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62-0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16-1·59), representing a 50% (42-58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1).

INTERPRETATION

In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease.

FUNDING

Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council.

A randomized controlled trial comparing a prepackaged low-residue diet with a restricted diet for colonoscopy preparation: the impact on the results of colonoscopy in adenoma detection

AIM

This study aimed to investigate the clinical utility of a prepackaged low-residue diet (PLD) compared with a restricted diet (RD) for colonoscopic bowel preparation.

METHOD

A prospective randomized controlled trial was carried out with patients undergoing colonoscopy. One hundred patients were randomly assigned to PLD and RD groups. In the RD group, the patients received an information sheet containing acceptable low-residue options and instructions from the medical staff. All patients received 10 ml sodium picosulphate the day before colonoscopy and 1 l of polyethylene glycol with ascorbic acid (PEG-A) on the day of the colonoscopy. If the bowel preparation was not adequate, an additional PEG-A solution was given. The primary outcome was the efficacy of colonic cleansing as rated by the Boston Bowel Preparation Scale (BBPS). The additional amount of PEG-A solution, adenoma detection rate and patient tolerance were assessed as secondary outcomes.

RESULTS

The BBPS score in the PLD group was 7.3 ± 1.7 compared with 6.5 ± 1.7 in the RD group. The quality of bowel preparation was significantly better in the PLD group (P < 0.05). The mean amount of additional PEG-A solution in the PLD group was smaller than in the RD group (293.8 ± 474.8 vs 444.1 ± 625.0 ml), but there was no statistical difference between the two groups. Adenoma detection rates and patient tolerance were similar in the two groups.

CONCLUSION

Prepackaged low-residue diets PLD is superior to RD for bowel preparation for colonoscopy.

Clinical outcomes of endoscopic resection for nonampullary duodenal high-grade dysplasia and intramucosal carcinoma

This study retrospectively analyzed the clinical outcomes of endoscopic resection of 26 sporadic (i. e., not associated with polyposis syndrome) nonampullary duodenal lesions representing high-grade dysplasia or intramucosal carcinoma (duodenal HGD/IMC) in 23 patients. No severe complications such as perforation were observed, but three cases of delayed bleeding were seen. The use of endoscopic clips significantly decreased the delayed bleeding rate (0/19, 0%) compared with cases in which clips were not used (3/7, 42.9%; P = 0.013, χ2 test). Eighteen lesions (69.2%) were removed by en bloc resection. The follow-up period after resection was 25.5 ± 23.3 months. Two lesions (7.7%) that recurred locally were detected at the first surveillance endoscopy 3 months after resection. These lesions were 22 and 15 mm in size respectively and were resected piecemeal. Endoscopic resection is an effective and safe procedure for treating duodenal HGD/IMC. En bloc resection and prophylactic clip usage are encouraged.

Predictive factors of response to intravenous ciclosporin in severe ulcerative colitis: the development of a novel prediction formula

BACKGROUND

When treating patients with severe ulcerative colitis (UC), accurate prediction of drug efficacy contributes to early clinical decision-making.

AIM

To identify predictive factors and to develop a reliable prediction formula and a decision tree of response to intravenous ciclosporin treatment for severe UC.

METHODS

Patients included in this study were those diagnosed with refractory severe UC who had undergone ciclosporin treatment between December 2004 and March 2011 at a tertiary referral centre in Japan. Demographic and clinical parameters from all patients were analysed by multivariate statistics.

RESULTS

Fifty-two patients were included in this study (36.5% men with an average age of ciclosporin initiation of 40.2 ± 15.6 years). Thirty-four patients (65.4%) were responders to the treatment with ciclosporin and avoided colectomy, 18 patients (34.6%) were nonresponders and underwent colectomy. Stepwise multiple logistic regression analysis identified four independent predictive factors of response to intravenous ciclosporin: age at hospitalisation (AGE), platelet count (×10(4) /μL) on the first day (PLA), Lichtiger score on the third day (LIC) and total protein (g/dL) on the third day minus total protein on the first day (ΔTP). The calculation formula (8.5 - 0.16 × AGE + 0.21 × PLA - 0.61 × LIC + 2.3 × ΔTP < 0) predicted colectomy with an accuracy of 88.5% and the decision tree predicted colectomy with an accuracy of 90.4%.

CONCLUSION

The novel calculation formula and the decision tree effectively predict the clinical outcome of ciclosporin treatment for severe ulcerative colitis as early as on day 3 after starting ciclosporin treatment.

Pleiotropic effects of mitiglinide in type 2 diabetes mellitus

This study investigated the effects of mitiglinide in 16 patients with type 2 diabetes mellitus treated with 30 mg/day mitiglinide, divided into three doses given just before each meal, for approximately 12 months. A 450 kcal meal tolerance test was performed at baseline and after 3, 6 and 12 months, and levels of plasma glucose and immunoreactive insulin were measured. Various parameters of glucose metabolism and lipid metabolism, urinary albumin and markers of atherosclerosis, coagulation and fibrinolysis were also determined. Mitiglinide showed a rapid stimulatory effect on insulin secretion and reduced the levels of plasma glucose. The free fatty acid level significantly decreased at 60 min after the meal tolerance test. Mitiglinide also significantly lowered glycosylated haemoglobin and raised 1,5-anhydroglucitol after 6 months, and significantly decreased urinary albumin after 12 months. These data indicate that mitiglinide may have beneficial effects not only on glycaemic control but also on lipid metabolism and urinary albumin excretion, and may have a role in the prevention of the vascular complications of diabetes.

Clinical significance of circulating hepatocyte growth factor, a new risk marker of carotid atherosclerosis in patients with Type 2 diabetes

AIMS

Recent studies have provided increasing evidence that hepatocyte growth factor (HGF) has a pathophysiological role in the development of diabetic complications. We set out to determine the relationship between serum HGF and risk factors for macroangiopathy including carotid atherosclerosis. Carotid atherosclerosis is an established and important risk factor for both cerebral and coronary artery diseases.

METHODS

We studied 89 patients (48 males, 41 females, mean age 62.5 +/- 10.3 years) with Type 2 diabetes (DM).

RESULTS

Serum levels of HGF correlated positively with both intimal-media thickness (IMT) (r = 0.24, P = 0.0248) and plaque score (r = 0.27, P = 0.0126). In multiple regression analysis, serum HGF was associated independently with IMT (standardized beta = 0.28, P = 0.0499). We also found that both IMT and plaque score were higher in patients with ischaemic heart disease (IHD) than in patients without IHD, and that plaque score in patients with lacunar infarcts was higher than in patients without lacunar infarcts.

CONCLUSIONS

Serum HGF concentration may be a new marker of atherosclerotic complications in patients with Type 2 DM.

Independent accumulations of tau and amyloid beta-protein in the human entorhinal cortex

BACKGROUND

Previous studies have repeatedly described that neurofibrillary tangles arise earlier than senile plaques (SPs) in the entorhinal cortex, but one study suggested that SPs, if present, enhance the former lesions. All of these studies were performed at the histologic or immunocytochemical level, which may not accurately reflect the actual levels of amyloid beta-protein (Abeta) and tau.

OBJECTIVE

To determine whether there is significant interaction between Abeta and tau in the human entorhinal cortex with regard to the Braak stage.

METHODS

Biochemical studies were conducted on 50 brains from elderly people, who were mainly at Braak stages I to III. All the cases were examined neuropathologically and staged according to Braak and Braak. A small piece of brain tissue for each case was dissected from the anterior portion of the right entorhinal cortex. The amounts of tau and Abeta in the insoluble fraction of the tissue were quantified using western blotting.

RESULTS

The levels of tau and possibly Abeta42 in the entorhinal cortex appeared to rise steeply at approximately age 75. The levels of insoluble tau increased as the Braak stage increased from I to II; however, it had a tendency to remain between stages II and III. The levels of Abeta42 showed a small increase, whereas those of Abeta40 increased continuously as the Braak stage advanced. In contrast, the extent of Abeta42 accumulation increased with increasing Braak stage for SPs. There was no significant correlation between the levels of insoluble tau and Abeta42 in the entorhinal cortex. Even if Abeta did not accumulate to significant extents, substantial accumulation of insoluble tau occurred.

CONCLUSION

Accumulations of tau and amyloid beta-protein occur independently in the human entorhinal cortex.

Evaluating the performance of a hybrid artificial liver support system with a recoverable hepatic failure rat model

To evaluate the performance of an artificial liver, we created a recoverable hepatic failure rat model. This involves a 30-60 minute warm ischemia, via clamping, of one-third of the liver with a partial (two-thirds) hepatectomy. Variations on this method provide for the possibility of several modes of hepatic failure. Survival time of the rats was prolonged (35%) by applying our hybrid artificial liver. However, the extracorporeal circulation is a considerable burden to the rat. Therefore, we need to apply the hybrid artificial liver intermittently and repeatedly.

Molecular basis for selectivity of high affinity peptide antagonists for the gastrin-releasing peptide receptor

Few gastrointestinal hormones/neurotransmitters have high affinity peptide receptor antagonists, and little is known about the molecular basis of their selectivity or affinity. The receptor mediating the action of the mammalian bombesin (Bn) peptide, gastrin-releasing peptide receptor (GRPR), is an exception, because numerous classes of peptide antagonists are described. To investigate the molecular basis for their high affinity for the GRPR, two classes of peptide antagonists, a statine analogue, JMV594 ([d-Phe(6),Stat(13)]Bn(6-14)), and a pseudopeptide analogue, JMV641 (d-Phe-Gln-Trp-Ala-Val-Gly-His-Leupsi(CHOH-CH(2))-(CH(2))(2)-CH(3)), were studied. Each had high affinity for the GRPR and >3,000-fold selectivity for GRPR over the closely related neuromedin B receptor (NMBR). To investigate the basis for this, we used a chimeric receptor approach to make both GRPR loss of affinity and NMBR gain of affinity chimeras and a site-directed mutagenesis approach. Chimeric or mutated receptors were transiently expressed in Balb/c 3T3. Only substitution of the fourth extracellular (EC) domain of the GRPR by the comparable NMBR domain markedly decreased the affinity for both antagonists. Substituting the fourth EC domain of NMBR into the GRPR resulted in a 300-fold gain in affinity for JMV594 and an 11-fold gain for JMV641. Each of the 11 amino acid differences between the GRPR and NMBR in this domain were exchanged. The substitutions of Thr(297) in GRPR by Pro from the comparable position in NMBR, Phe(302) by Met, and Ser(305) by Thr decreased the affinity of each antagonist. Simultaneous replacement of Thr(297), Phe(302), and Ser(305) in GRPR by the three comparable NMBR amino acids caused a 500-fold decrease in affinity for both antagonists. Replacing the comparable three amino acids in NMBR by those from GRPR caused a gain in affinity for each antagonist. Receptor modeling showed that each of these three amino acids faced inward and was within 5 A of the putative binding pocket. These results demonstrate that differences in the fourth EC domain of the mammalian Bn receptors are responsible for the selectivity of these two peptide antagonists. They demonstrate that Thr(297), Phe(302), and Ser(305) of the fourth EC domain of GRPR are the critical residues for determining GRPR selectivity and suggest that both receptor-ligand cation-pi interactions and hydrogen bonding are important for their high affinity interaction.

Tyrosine 220 in the 5th transmembrane domain of the neuromedin B receptor is critical for the high selectivity of the peptoid antagonist PD168368

Peptoid antagonists are increasingly being described for G protein-coupled receptors; however, little is known about the molecular basis of their binding. Recently, the peptoid PD168368 was found to be a potent selective neuromedin B receptor (NMBR) antagonist. To investigate the molecular basis for its selectivity for the NMBR over the closely related receptor for gastrin-releasing peptide (GRPR), we used a chimeric receptor approach and a site-directed mutagenesis approach. Mutated receptors were transiently expressed in Balb 3T3. The extracellular domains of the NMBR were not important for the selectivity of PD168368. However, substitution of the 5th upper transmembrane domain (uTM5) of the NMBR by the comparable GRPR domains decreased the affinity 16-fold. When the reverse study was performed by substituting the uTM5 of NMBR into the GRPR, a 9-fold increase in affinity occurred. Each of the 4 amino acids that differed between NMBR and GRPR in the uTM5 region were exchanged, but only the substitution of Phe(220) for Tyr in the NMBR caused a decrease in affinity. When the reverse study was performed to attempt to demonstrate a gain of affinity in the GRPR, the substitution of Tyr(219) for Phe caused an increase in affinity. These results suggest that the hydroxyl group of Tyr(220) in uTM5 of NMBR plays a critical role for high selectivity of PD168368 for NMBR over GRPR. Receptor and ligand modeling suggests that the hydroxyl of the Tyr(220) interacts with nitrophenyl group of PD168368 likely primarily by hydrogen bonding. This result shows the selectivity of the peptoid PD168368, similar to that reported for numerous non-peptide analogues with other G protein-coupled receptors, is primarily dependent on interaction with transmembrane amino acids.

Glycosylation of the gastrin-releasing peptide receptor and its effect on expression, G protein coupling, and receptor modulatory processes

Many gastrointestinal G protein-coupled receptors are glycosylated; however, which potential glycosylation sites are actually glycosylated and their role in receptor transduction or receptor modulation (internalization, down-regulation, desensitization) is largely unknown. We used site-directed mutagenesis to address these issues with the gastrin-releasing peptide receptor (GRP-R). Each of the four potential glycosylation sites was mutated by converting the Asn (N) to Gln (Q). Transient expression in CHOP cells demonstrated that changing Asn(24) or Asn(191) inhibited GRP-R cell surface expression, whereas elimination of Asn(5) and Asn(20) had no effect. Using ligand cross-linking studies in stable mutants expressed in Balb 3T3 cells, all four potential extracellular sites were glycosylated with carbohydrate residues of approximately 13 kDa on Asn(5), 10 kDa on Asn(20), 5 kDa on Asn(24), and 9 kDa on Asn(191). Removal of three glycosylation sites (N5,20,24,Q mutant) did not alter receptor affinity or G protein coupling; therefore, it could be speculated that deglycosylation at Asn(191) might be responsible for the altered G protein coupling seen with complete enzymatic deglycosylation of the native receptor previously reported. Removal of any single glycosylation site did not interfere with GRP-R induced chronic desensitization or down-regulation. However, elimination of all three NH(2)-terminal sites (N5,20,24) markedly attenuated both processes, with no effect on acute homologous desensitization and with only a minimal alteration of GRP-R internalization, supporting the findings of other studies that suggest that chronic desensitization and down-regulation are functionally coupled, distinct from acute desensitization and distinct from internalization. These data show that separate and specific glycosylation sites are important for GRP-R trafficking to the cell surface, ligand binding, G protein coupling, chronic desensitization, and down-regulation.

Changes of cytokines during the course of graft-versus-host disease following bone marrow transplantation: a case report

Allogeneic bone marrow transplantation was performed in a 24-year-old woman with acute myelogenous leukemia in the first remission (FAB classification: M4). Graft-versus-host disease occurred from around day 150 after bone marrow transplantation. The levels of tumour necrosis factor-alpha, interleukin 12, and intercellular adhesion molecule-1 were elevated in the early stage of graft-versus-host disease, followed by elevation of interleukin 10 and interleukin 8. Her symptoms subsequently improved and all of these parameters became normal. The levels of thrombomodulin and plasminogen activator inhibitor type 1 showed changes that were in parallel with the clinical course. Interleukin 1beta, interleukin 6, interleukin 2, and interferon-gamma showed no changes throughout the course of her graft-versus-host disease. These findings suggested the possibility that release of inflammatory molecules occurred at the onset of graft-versus-host disease and caused vascular endothelial damage, which led to the exacerbation of her disease.

A role of PKC in the improvement of energy metabolism in preconditioned heart

OBJECTIVE

A possible link between activation of PKC and improvement of energy metabolism during reperfusion in ischemic preconditioning hearts was examined.

METHODS

Isolated perfused rat hearts were preconditioned by 5-min ischemia and 5-min reperfusion in the presence and absence of a PKC inhibitor polymyxin B (50 microM) and then subjected to 40-min sustained ischemia and subsequent 30-min reperfusion. In another set of experiments, the hearts pretreated with and without a PKC activator PMA (15 pmol/5 min) were subjected to the sustained ischemia and reperfusion. Myocardial high-energy phosphates, glycolytic intermediates and mitochondrial oxygen consumption capacity were determined at appropriate experimental sequences.

RESULTS

Preconditioning enhanced the recovery of cardiac function such as left ventricular developed pressure, heart rate and rate-pressure product of the reperfused heart, suppressed the release of creatine kinase, enhanced the reperfusion-induced restoration of myocardial high-energy phosphates, attenuated the reperfusion-induced accumulation in glucose 6-phosphate and fructose 6-phosphate contents, abolished the ischemia-induced increase in tissue lactate content and prevented the ischemia-induced decrease in mitochondrial oxygen consumption capacity. Treatment of the perfused heart with PMA mimicked the effects of preconditioning on post-ischemic contractile function, enzyme release, levels of myocardial energy store, glycolytic intermediates and lactate, and mitochondrial function. Polymyxin B-treatment abolished the preconditioning-induced recovery of post-ischemic contractile function, the suppression of the release of CK, the restoration of myocardial energy store, and the preservation of mitochondrial function, whereas it did not cancel the improvement of glycolytic intermediate levels and the reduction in tissue lactate accumulation. Post-ischemic contractile function was closely related to restoration of high-energy phosphates and mitochondrial oxygen consumption capacity in all hearts subjected to ischemia/reperfusion.

CONCLUSION

The results suggest that activation of PKC and preservation of mitochondrial function are closely linked with each other in the preconditioned heart, which may lead to the improvement of post-ischemic contractile function.

Rat and guinea pig pancreatic acini possess both VIP(1) and VIP(2) receptors, which mediate enzyme secretion

Pancreatic acini from most species possess vasoactive intestinal peptide (VIP) receptors. Recently, two subtypes of VIP receptors, VIP(1)-R and VIP(2)-R, were cloned. Which subtype exists on pancreatic acini or mediates secretion is unclear. To address this, we examined pancreatic acini from both rat and guinea pig. VIP(1)-R and VIP(2)-R mRNA were identified in dispersed acini from both species by Northern blot analysis and in rat by Southern blot analysis. With the use of the VIP(2)-R-selective ligand Ro-25-1553 in both species, inhibition of binding of (125)I-labeled VIP to acini showed a biphasic pattern with a high-affinity component (10%) and a second representing 90%. The VIP(1)-R-selective ligand, [Lys(15),Arg(16),Leu(27)]VIP-(1-7)-GRF-(8-27), gave a monophasic pattern. Binding of Ro-25-1553 was better fit by a two-site model. In both rat and guinea pig acini, the dose-response curve of Ro-25-1553 for stimulation of enzyme secretion was biphasic, with a high-affinity component of 10-15% of the maximal secretion and a low-affinity component accounting for 85-90%. At low concentrations (10 nM) of Ro-25-1553 and [Lys(15),Arg(16), Leu(27)]VIP-(1-7)-GRF(8-27), which only occupy VIP receptors, a 4-fold and a 56-fold increase in cAMP occurred, respectively. These results show that both VIP(1)-R and VIP(2)-R subtypes exist on pancreatic acini of rat and guinea pig, their activation stimulates enzyme secretion by a cAMP-mediated mechanism, and the effects of VIP are mediated 90% by activation of VIP(1)-R and 10% by VIP(2)-R. Because VIP has a high affinity for both VIP-R subtypes, its effect on pancreatic acini is mediated by two receptor subtypes, which will need to be considered in future studies of the action of VIP in the pancreas.

Comparative pharmacology of the nonpeptide neuromedin B receptor antagonist PD 168368

The mammalian peptide neuromedin B (NMB) and its receptor are expressed in a variety of tissues; however, little is definitively established about its physiological actions because of the lack of potent, specific antagonists. Recently, the peptoid PD 168368 was found to be a potent human NMB receptor antagonist. Because it had been shown previously that either synthetic analogs of bombesin (Bn) or other receptor peptoid or receptor antagonists function as an antagonist or agonist depends on animal species and receptor subtype studied, we investigated the pharmacological properties of PD 168368 compared with all currently known Bn receptor subtypes (NMB receptor, gastrin-releasing peptide receptor, Bn receptor subtype 3, and Bn receptor subtype 4) from human, mouse, rat, and frog. In binding studies, PD 168368 had similar high affinities (K(i) = 15-45 nM) for NMB receptors from each species examined, 30- to 60-fold lower affinity for gastrin-releasing peptide receptors, and >300-fold lower affinity for Bn receptor subtype 3 or 4. It inhibited NMB binding in a competitive manner. PD 168368 alone did not stimulate increases in either intracellular calcium concentration or [(3)H]inositol phosphates in any of the cells studied but inhibited NMB-induced responses with equivalent potencies in cells containing NMB receptors. PD 168368 was only minimally soluble in water. When hydroxypropyl-beta-cyclodextrin rather than dimethyl sulfoxide was used as the vehicle, both the affinity and the antagonist potency of PD 168368 were significantly greater. The results demonstrate that PD 168368 is a potent, competitive, and selective antagonist at NMB receptors, with a similar pharmacology across animal species. PD 168368 should prove useful for delineating the biological role of NMB and selectively blocking NMB signaling in bioassays and as a lead for the development of more selective nonpeptide antagonists for the NMB receptor.

Pharmacology and cell biology of the bombesin receptor subtype 4 (BB4-R)

Recently, a fourth member of the bombesin (Bn) receptor family (fBB4-R) was isolated from a cDNA library from the brain of the frog, Bombina orientalis. Its pharmacology and cell biology are largely unknown, and no known natural cell lines or tissues possess sufficient numbers of fBB4-R's to allow either of these to be determined. To address these issues, we have used three different strategies. fBB4-R expression in cells widely used for other Bn receptor subtypes was unsuccessful as was expression in two frog cell lines. However, stable fBB4-R cell lines were obtained in CHO-K1 cells which were shown to faithfully demonstrate the correct pharmacology of the related Bn receptor, the GRP receptor, when expressed in these cells. [DPhe6,betaAla11,Phe13,Nle14]Bn(6-14) was found to have high affinity (Ki = 0.4 nM) for the fBB4 receptor and 125I-[DTyr6,betaala11,Phe13,Nle14]Bn(6-14) to be an excellent ligand for this receptor. The fBB4-R had a unique pharmacology for naturally occurring Bn-related agonists, with the presence of a penultimate phenylalanine being critical for high-affinity interaction. It also had a unique profile for six classes of Bn antagonists. The fBB4-R was coupled to phospholipase C with activation increasing [3H]inositol phosphates and mobilizing Ca2+ almost entirely from cellular sources. There was a close correlation between agonist the receptor occupation and the receptor activation. Three of the five classes of Bn receptor antagonists that interacted with higher affinity with the fBB4-R functioned as fBB4-R antagonists and two as partial agonists. fBB4-R activation stimulated increases in phospholipase D (PLD) over the same range of concentrations at which it activated phospholipase C. These results demonstrate that the fBB4 receptor has a unique pharmacology for agonists and antagonists and is coupled to phospholipase C and D. The availability of these cell lines, this novel ligand, and the identification of three classes of antagonists that can be used as lead compounds should facilitate the further investigation of the pharmacology and cell biology of the BB4 receptor.

Scrotal ulcer occurring in patients with acute promyelocytic leukemia during treatment with all-trans retinoic acid

Although all-trans retinoic acid (ATRA) has been shown to improve the outcome of patients with acute promyelocytic leukemia (APL) compared with chemotherapy alone, various adverse effects have been reported. We report here the development of scrotal ulcer in four patients with APL during ATRA treatment. ATRA 45 mg/m2 was administered orally to four patients with newly diagnosed APL, two of whom also received chemotherapy. Scrotal ulcers appeared in all four patients after a median of 22 days (range: 17-29 days) of ATRA treatment. ATRA was discontinued in only one patient, who was then treated with methylprednisolone pulse therapy. The fever resolved, and scrotal ulcer improved after this treatment. The other three patients were treated with steroid or antibiotic ointment for scrotal ulcers. ATRA was re-administered 2 years later in one patient who had relapse of APL. Ulcers appeared again on the scrotal and lower abdominal skin on day 27 of ATRA treatment. These findings strongly suggest that scrotal ulcer is a potential adverse effect of ATRA.

Identification of a unique ligand which has high affinity for all four bombesin receptor subtypes

Four subtypes of bombesin receptors are identified (gastrin-releasing peptide receptor, neuromedin B receptor, the orphan receptor bombesin receptor subtype 3 (BB3 or BRS-3) and bombesin receptor subtype 4 (BB4)), however, only the pharmacology of the gastrin-releasing peptide receptor has been well studied. This lack of data is due in part to the absence of a general ligand. Recently we have discovered a ligand, 125I-[D-Tyr6,betaAla11,Phe13,Nle14]bombesin-(6-1 4) that binds to BRS-3 receptors. In this study we investigate its ability to interact with all four bombesin receptor subtypes. In rat pancreatic acini containing only gastrin-releasing peptide receptor and in BB4 transfected BALB cells, this ligand and 125I-[Tyr4]bombesin, the conventional gastrin-releasing peptide receptor ligand, gave similar results for receptor number, affinity for bombesin and affinity for the unlabeled ligand. In neuromedin B receptor transfected BALB cells, this ligand and 125I-[D-Tyr0]neuromedin B, the generally used neuromedin B receptor ligand, gave similar results for receptor number, neuromedin B affinity or the unlabeled ligand affinity. Lastly, in BRS-3 transfected BALB cells, only this ligand had high affinity. For all four bombesin receptors this ligand had an affinity of 1-8 nM and was equal or greater in affinity than any other specific ligands for any receptor. The unlabeled ligand is specific for gastrin-releasing peptide receptors on rat pancreatic acini and did not inhibit binding of 125I-cholecystokinin octapeptide (125I-CCK-8), 125I-vasoactive intestinal peptide (125I-VIP) or 125I-endothelin to their receptors. The unlabeled ligand was an agonist only at the gastrin-releasing peptide receptor in rat acini and did not interact with CCK(A) receptors or muscarinic M3 acetylcholine receptors to increase [3H]inositol phosphates. These results demonstrate 125I-[D-Tyr6,betaAla11,Phe13,Nle14]bombesin-(6-1 4) is a unique ligand with high affinity for all subtypes of bombesin receptors. Because of the specificity for bombesin receptors, this ligand will be a valuable addition for such pharmacological studies as screening for bombesin receptor agonists or antagonists and, in particular, for investigating BRS-3 cell biology, a receptor for which no ligand currently exists.

[Effect of intensive vacuum cleaning in reducing house dust mite antigen in bed rooms of asthmatic children]

House dust mite (Dermatophagoides farinae) antigen was measured by enzyme-linked immunosorbent assay in house dust samples obtained from the bed rooms of asthmatic children and normal controls. In 37 rooms where regular vacuum cleaning was performed, the mean of D.f. antigen was 4.42 +/- 7.55 micrograms/m2. In the 24 bed rooms of asthmatic children, mean levels of D.f. antigen decreased significantly (p less than 0.05) after intensive cleaning (systematic cleaning) was continued for 4 weeks (0.78 +/- 0.93 micrograms/m2) compared to prior to initiation of systematic cleaning (4.12 +/- 6.31 micrograms/m2). Symptom scores decreased in 65% of the asthmatic children. In 8 bed rooms of normal controls, mean levels of D.f. antigen also showed a decrease after systematic cleaning (0.43 +/- 0.62 micrograms/m2) compared to before (5.59 +/- 12.46 micrograms/m2). However there was no significant difference in D.f. antigen between the bed rooms of asthmatic children and normal controls. Intensive cleaning markedly decreased the allergen in both groups, clearly suggesting effectiveness in the reduction of asthmatic attacks in patients and perhaps also in preventing sensitization of healthy children.