Substitution of Dmo1 with normal alleles results in decreased manifestation of diabetes in OLETF rats

AIM

Dmo1 (Diabetes Mellitus OLETF type I) is a major quantitative trait locus for dyslipidaemia, obesity and diabetes phenotypes in the Otsuka Long Evans Tokushima Fatty (OLETF) rat strain. To evaluate possible metabolic and pathological improvements generated by correction of the Dmo1 genetic pathway, we produced congenic lines, in which both OLETF Dmo1 alleles are replaced by the F344-derived genome.

METHODS

Congenic animals were produced by introgressing F344-derived Dmo1 alleles into the OLETF rat. Congenic animals of the fourth generation (BC4) were intercrossed to obtain F1 animals (BC4:F1). Animals of the next generation, BC4:F2, were used for this study. We used 23 BC4:F2 males harbouring homozygous replacement of the OLETF Dmo1 region with the F344-derived genome. Seven animals with OLETF-derived Dmo1 alleles were used as controls.

RESULTS

Dmo1-F344/F344 congenic rats showed significant decreases in body weight, abdominal fat weight, serum triacylglycerols, total cholesterol, food consumption and blood glucose after glucose loading (13%, 39%, 45%, 27%, 18% and 27% respectively; p < 0.05) compared with Dmo1-OLETF/OLETF animals. Furthermore, histopathological analysis of the kidney showed that mesangial sclerosis, hyalin deposits and deposition of PAS-positive substance were significantly lower in Dmo1-F344/F344 animals (p < 0.05).

CONCLUSION

Improvements in metabolic parameters and histopathological scores show that correction of the Dmo1 genetic pathway in the diabetic and mildly obese OLETF rat strain produces wide-ranging therapeutic effects. Thus, this pathway might represent a new drug target also applicable to humans.

Aortic and mitral valve replacement in a patient with acute febrile neutrophilic dermatosis (Sweet's syndrome): report of a case

A 29-year-old woman was admitted to our hospital with severe orthopnea, fever, and acute dermatosis. She had a 5-year history of episodic acute neutrophilic dermatosis and peripheral leukocytosis following a high fever, which were symptoms consistent with a diagnosis of Sweet's syndrome. Echocardiography revealed remarkable dysfunction of the left ventricle due to severe aortic regurgitation, which had not been present at a previous admission when mild mitral regurgitation was detected. The aortic and mitral valves were replaced with prosthetic valves on an emergency basis. The leaflets of the aortic valve were very thin and appeared fragile. The anterior leaflet of the mitral valve showed severe prolapse due to the torn chordae and hypoplasia of the posterior strut chordae. Her postoperative course was uneventful. Microscopic examination revealed fibrosal degeneration and the infiltration of lymphocytes and macrophages into both heart valves. This may be the first case report of valvulitis and Sweet's syndrome occurring simultaneously.

Nitric oxide is generated in smooth muscle layer by neurokinin A and counteracts constriction in guinea pig airway

It has been reported that several bronchoconstrictors generate nitric oxide (NO), counteracting bronchoconstriction, and removal of bronchial epithelia reduces NO production. However, it has not been elucidated whether neurokinin A (NKA), a potent bronchoconstrictor liberated from nerve terminals, generates NO. Specific questions in this study were (1) does NKA also generate NO, (2) does NO counteract NKA-induced bronchoconstriction, and (3) does the NO generation require bronchial epithelial cells? In an in vivo study exogenous as well as endogenous (capsaicin-induced) NKA increased airway opening pressure (P(ao)) and the exhaled NO level, and both were inhibited by an antagonist selective for NK(2) receptor (a receptor for NKA), SR48968. The exhaled NO level became negligible with an inhibitor of NO synthase (NOS) type 1-3 (N(G)-nitro-L-arginine methyl ester, L-NAME) with increased P(ao), but not with a NOS type 2 inhibitor. In an in vitro study, NKA increased the nitrite/nitrate level in superfused fluid of tracheal segments. Removing smooth muscle reduced nitrite/nitrate in the fluid to negligible levels, while the level was unchanged with removal of the epithelia. Pretreatment with l-NAME enhanced the tension of epithelia-removed tracheal segments. These findings indicate that (1) NKA generates NO, (2) NO counteracts NKA-induced bronchoconstriction, and (3) NKA activates NOS in the muscle layer, independently of bronchial epithelia.

Synthetic activity of Sso DNA polymerase Y1, an archaeal DinB-like DNA polymerase, is stimulated by processivity factors proliferating cell nuclear antigen and replication factor C

DNA replication efficiency is dictated by DNA polymerases (pol) and their associated proteins. The recent discovery of DNA polymerase Y family (DinB/UmuC/RAD30/REV1 superfamily) raises a question of whether the DNA polymerase activities are modified by accessory proteins such as proliferating cell nuclear antigen (PCNA). In fact, the activity of DNA pol IV (DinB) of Escherichia coli is enhanced upon interaction with the beta subunit, the processivity factor of DNA pol III. Here, we report the activity of Sso DNA pol Y1 encoded by the dbh gene of the archaeon Sulfolobus solfataricus is greatly enhanced by the presence of PCNA and replication factor C (RFC). Sso pol Y1 per se was a distributive enzyme but a substantial increase in the processivity was observed on poly(dA)-oligo(dT) in the presence of PCNA (039p or 048p) and RFC. The length of the synthesized DNA product reached at least 200 nucleotides. Sso pol Y1 displayed a higher affinity for DNA compared with pol IV of E. coli, suggesting that the two DNA polymerases have distinct reason(s) to require the processivity factors for efficient DNA synthesis. The abilities of pol Y1 and pol IV to bypass DNA lesions and their sensitive sites to protease are also discussed.

Survey of antibiotic resistance in Pseudomonas aeruginosa by The Tokyo Johoku Association of Pseudomonas Studies

Pseudomonas aeruginosa resistance (minimum inhibitory concentration [MIC], > or =16 microg/ml defined as resistant) to meropenem, imipenem, panipenem, piperacillin, ceftazidime, cefozopran, cefoperazone, sulbactam/cefoperazone, amikacin, and tobramycin, as well as cross-resistance profiles, were investigated in P. aeruginosa strains isolated at eight hospitals in the Johoku area, Tokyo, during November 1998. Overall, 8.3% of isolates were imipenem-resistant and 4.6% were ceftazidime-resistant. However, the incidence of antibiotic-resistant P. aeruginosa was distinctly different at each hospital. P. aeruginosa resistance to imipenem ranged from (MIC) 1 to 64 microg/ml (MIC90 32 microg/ml), and its resistance to ceftazidime ranged from 2 to more than 128 microg/ml (MIC90, 64 microg/ml). Meropenem (MIC range, < or =0.25 to 16 microg/ml) was more active than panipenem (MIC range, 2 to 64 microg/ml). Cefozopran was more active than piperacillin, cefoperazone, or sulbactam/cefoperazone, but many strains were resistant to cefoperazone (17/57). Our analysis found cross-resistance to many beta-lactams, but the degree of cross-resistance was very variable.

Effect of neutral endopeptidase inhibitor on bradykinin-induced bronchoconstriction

To evaluate whether neutral endopeptidase (NEP) inhibitors have adverse respiratory effects, the influence of a NEP inhibitor on bradykinin (BK)-induced bronchoconstriction was investigated. In anesthetized and artificially ventilated guinea pigs, changes in airway opening pressure (Pao) were measured as an index of bronchoconstriction. An infusion of phosphoramidon (3 mg kg(-1) h(-1)), a NEP inhibitor, significantly enhanced the bronchoconstriction induced by high-dose BK (30 nmol kg(-1), i.v.). Capsaicin (0.1 mg kg(-1), i.v.) and SR48968 (0.3 mg kg(-1), i.v.), an NK2 receptor antagonist, significantly inhibited the phosphoramidon-induced enhancement of BK-induced bronchoconstriction, although FK888 (3 mg kg(-1), i.v.), an NK1 receptor antagonist, did not. Both neurokinin A (NKA) (0.1-3 nmol kg(-1), i.v.) and substance P (SP) (0.1-3 nmol kg(-1), i.v.) induced dose-dependent bronchoconstriction which was enhanced by phosphoramidon infusion, although these enhancements were more prominent in the NKA series. Phosphoramidon partially inhibited BK degradation in lung homogenate, and both NKA and SP degradation in the lung homogenate were significantly suppressed by phosphoramidon. In bronchoalveolar lavage fluid (BALF), levels of NKA and SP were significantly elevated after a bolus of BK with a phosphoramidon infusion. These results suggest that NEP inhibitors may have adverse respiratory effects resulting from inhibition of the degradation of neurokinins, but mainly of NKA, when a large amount of BK is generated.

Adenylate cyclase/protein kinase A signaling pathway enhances angiogenesis through induction of vascular endothelial growth factor in vivo

We previously reported that endogenous prostaglandins (PGs) may increase cAMP facilitated angiogenesis through the induction of vascular endothelial growth factor (VEGF) in rat sponge implantation models. In the present experiment, we tested whether or not adenylate cyclase / protein kinase A (AC/PKA)-dependent VEGF induction enhanced angiogenesis in this model. Topical daily injections of 8-bromo-cAMP enhanced angiogenesis in a dose-dependent manner. Forskolin, an activator of AC, also facilitated angiogenesis as did amrinone, an inhibitor of phosphodiesterase. VEGF induction was confirmed by the increased levels in the fluids in the sponge matrix after topical injection of 8-bromo-cAMP. Immunohistochemical investigation further revealed the VEGF-expressed cells in the sponge granulation tissues to be fibroblasts, and the intensity of positive reactions was enhanced by 8-bromo-cAMP, forskolin and amrinone. Angiogenesis without topical injections of the above compounds was suppressed by SQ22,536, an inhibitor for AC, or H-89, an inhibitor for PKA, with concomitant reductions in VEGF levels. Daily topical injections of neutralizing antibody or anti-sense oligonucleotide against VEGF significantly suppressed angiogenesis. PGE2-induced angiogenesis was suppressed with SQ22,536 or H-89. These results suggested that AC/PKA-dependent induction of VEGF certainly enhanced angiogenesis and that pharmacological tools for controlling this signaling pathway may be able to facilitate the management of conditions involving angiogenesis.

Right vagal nerve stimulation for coronary anastomosis without cardiopulmonary bypass: investigation in dogs

BACKGROUND

The purpose of this study is to assess the potential of right vagal nerve stimulation for reducing the heart rate during coronary anastomosis without cardiopulmonary bypass.

METHODS

Through the fourth left intercostal space, left internal thoracic artery grafts were sutured to the left anterior descending artery with the heart beating. In Group I (n=7), two dogs underwent right cervical vagal stimulation alone and five dogs underwent right cervical vagal stimulation during intravenous infusion of diltiazem or verapamil. In Group II (n=3), one dog underwent right thoracic vagal stimulation alone and two dogs underwent right thoracic vagal stimulation during intravenous infusion of diltiazem or verapamil. The thoracic vagal nerve was isolated endoscopically. The electrocardiogram and aortic pressure were monitored during interventions.

RESULTS

In Group I, cervical vagal stimulation reduced the heart rate from 190 to 45 and 180 to 42 b/min. During intravenous infusion of diltiazem or verapamil, cervical vagal stimulation caused ventricular arrest. In Group II, thoracic vagal stimulation decreased the heart rate from 205 to 70 b/min, and stimulation during intravenous infusion of diltiazem caused ventricular arrest.

CONCLUSIONS

Right vagal stimulation during intravenous infusion of diltiazem or verapamil has potential value as a technique for reducing the heart rate during coronary anastomosis without cardiopulmonary bypass.

[Genome research and anticancer chemotherapy]

Worldwide research on the human genome is having a major impact on medical science and advanced medicine, although the detailed function and interaction of most genes remain unclear. The elucidation of human genome data makes it possible to take global views of biological processes and characteristics of cancer and individual drug response. This brings a number of new challenges such as genome based drug development and tailored cancer chemotherapy based on the individual genomic make-up. When a disease gene is identified, truly effective drugs targeting the genes can be developed. When biological characteristics such as polymorphism and gene expression profiles are closely related to drug response, an individually optimized drug therapy can be realized. cDNA microarray technology and new high-throughput single nucleotide polymorphism (SNP) screening offer great hope for such a global view by providing a systematic way to survey DNA and RNA variation. Evolutionary engineering techniques continue to be developed, which significantly promotes studies to understand molecular mechanisms causing diseases, novel disease genes, and genes related to drug response. Such progress in genome research and the functional analysis may revolutionize the anticancer chemotherapy world. The possible contribution of genome research to anticancer chemotherapy and problems of the day are reviewed herein.

Proinflammatory characteristics of a nonpeptide bradykinin mimic, FR190997, in vivo

1. Proinflammatory potency of the nonpeptide bradykinin (BK) B(2) receptor agonist FR190997 (8-[2,6-dichloro-3-[N-[(E)-4-(N-methylcarbamoyl)cinnamidoacetyl]-N-methylamino]benzyloxy]-2-methyl-4-(2-pyridylmethoxy)quinoline) was investigated. 2. Intradermal injection of FR190997 (0.03 - 3 nmol site(-1)) into dorsal skin of rats increased vascular permeability in a dose-dependent manner. The effect was less than that of BK, but it was long-acting and was inhibited by treatment with FR173657 (3 mg kg(-1), p.o.). Captopril (10 mg kg(-1), i.p.) did not enhance the plasma extravasation by FR190997 (0.3 nmol site(-1)) in the presence of soybean trypsin inhibitor (SBTI, 30 microg site(-1)). 3. Subcutaneous injection of FR190997 (3 nmol site(-1)) into the hindpaw of mice markedly induced paw swelling. The oedema lasted up to 3 h after the injection. Administration of indomethacin or NS-398 (10 mg kg(-1), i.p.) significantly reduced it at 3 h after the injection. 4. Simultaneous i.p. injection of prostaglandin (PG) E(2) (1 nmol site(-1)) or beraprost sodium (0.5 nmol site(-1)) with FR190997 (5 nmol site(-1)) greatly enhanced frequency of writhing reactions in mice. 5. FR190997 (0.3 - 30 nmol kg(-1), i.v.) showed less increase in airway opening pressure (Pao) in the guinea-pig after i.v. injection. Furthermore, FR190997 (0.03 - 30 nmol) resulted in a very weak contraction of tracheal ring strips and lung parenchymal sections in vitro. 6. In mice sponge implants, topical application of FR190997 increased angiogenesis and granulation with enhanced expressions of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) mRNAs. 7. These results indicate that FR190997 has proinflammatory long-lasting characteristics and it might be 'a stable tool' for studying the role of BK B(2) receptor in vivo.

Effects of Dmo1 on obesity, dyslipidaemia and hyperglycaemia in the Otsuka Long Evans Tokushima Fatty strain

Whole-genome scans have identified Dmo1 as a major quantitative trait locus (QTL) for obesity and dyslipidaemia in the Otsuka Long Evans Tokushima Fatty (OLETF) rat. We have produced congenic rats for the Dmo1 locus, using marker-assisted speed congenic protocols, enforced by selective removal of other QTL regions (QTL-marker-assisted counterselection), to efficiently transfer chromosomal segments from non-diabetic Fischer 344 (F344) rats into the OLETF background. In the third generation of congenic animals, we observed a substantial therapeutic effect of the Dmo1 locus on lipid metabolism, obesity control and plasma glucose homeostasis. We conclude that single-allele correction of an impaired genetic pathway can generate a substantial therapeutic effect, despite the complex polygenic nature of type II diabetic syndromes.

[Glycopeptides]

Glycopeptides(Vancomycin(VCM), Teicoplanin(TEIC)) are effective against Gram positive cocci(GPC) and mainly prescribing for Methicillin Resistant Staphylococcus aureus(MRSA) infection in Japan. Mode of actions are little bit difference between VCM and TEIC, for example the rate of protein binding, post antibiotic effect and half-life time. Effect of glycopeptide depend on the above MIC. To keep the effective serum concentrations of the drug, recommended the method of loading dose for TEIC and the method of continuous drip infusions for VCM. Also keep the effective serum concentrations shows to shorten the duration of treatment and to protect for development of resistant strains. Biofilm diseases caused by P. aeruginosa, MRSA and MRSE are treated by combination therapy with Fosfomycin(FOM). The most powerful intensive chemotherapy (FOM + Sulbactam/Cefoperazon + Glycopeptides) shows superior effects against multiple infections caused by P. aeruginosa and MRSA.

[Endogenous prostaglandins and angiogenesis]

Angiogenesis is a process involved in several physiological events including embryonic development, female reproductive cycle placentation and wound repair. It also plays a part in various pathological conditions such as tumor growth, diabetic retinopathy and rheumatoid arthritis. Angiogenesis is a very complex multistep process involving a variety of biologically active substances, among which are the prostaglandins (PGs), which can induce several growth factors and proliferation of endothelial cells in vitro and in vivo. Angiogenesis is reportedly enhanced by prostaglandins (PGs). We investigated whether or not COX-2 mediated angiogenesis in chronic and proliferate granuloma. In rat sponge implants, angiogenesis was gradually developed over a 14-day experimental period as granuloma formed. In sponge granuloma, mRNA of COX-1 was constitutively expressed, whereas that of COX-2 was increased with neovascularization in parallel with the increased expression of vascular endothelial growth factor (VEGF). bFGF-stimulated angiogenesis was inhibited by indomethacin or a selective COX-2 inhibitor, NS-398. These results suggested that endogenous PGs generated through COX-2 may enhance the neovascularization in sponge granuloma by increased expression of VEGF and that a COX-2 inhibitor would facilitate the management of conditions involving angiogenesis.

Coronary artery bypass grafting in patients with dialysis-dependent renal failure

This study identified preoperative characteristics of dialysis patients undergoing coronary artery bypass grafting (CABG) and determined the early and long-term results. We retrospectively analyzed the data of 60 patients (mean age 60.8 +/- 7.6 years) with end-stage renal disease who underwent CABG between 1982 and 1999. Seventeen (28%) patients underwent CABG for unstable angina, and 9 (15%) patients required preoperative intraaortic balloon pumping. The incidence of congestive heart failure (18%) and diseased aorta (42%) was higher in the dialysis group. In-hospital mortality in the dialysis group was 13% (8/60). The estimated survival rate at 5 and 10 years in the dialysis patients was 55.6 +/- 8.8% and 31.8 +/- 11.6%, respectively. The cardiac event-free rate, excluding the in-hospital mortality, was 62.5 +/- 9.9% at 5 years. Although the early and long-term results of CABG in dialysis patients were inferior to those of nondialysis patients, CABG in dialysis-dependent patients allows the patients to continue their dialysis therapy and to improve their functional status.

Effects of oral administration of Echinacea purpurea (American herb) on incidence of spontaneous leukemia caused by recombinant leukemia viruses in AKR/J mice

Four-week-old female AKR/J mice were given oral doses of powdered leaves from Echinacea purpurea three times weekly for 8 weeks (7.5 mg/mouse/week): controls received phosphate-buffered saline. Mean survival age of experimental AKR/J mice treated with the E. purpurea preparation was significantly prolonged and enlargement of thymic lymphoma in experimental mice was significantly suppressed compared with controls. In normal 3-week-old female AKR/J mice, mortality from thymic lymphoma was delayed markedly after injection into the thymus of cell-free extract of thymus from the experimental 28-week-old female AKR/J mice that received the oral E. purpurea preparation was injected directly into the thymus. Proliferation of endogenous recombinant murine leukemia viruses (MuLV) in the thymus was markedly inhibited after the first oral administration of the E. purpurea preparation as compared with untreated controls (final age, 28 weeks). Production of endogenous interferon (IFN)-gamma in AKR/J mice was also effectively augmented by the oral treatment with the E. purpurea preparation, however, the production of other cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-12 was minimal. These results suggest that this suppressive effects on spontaneously occurring leukemia caused by endogenous recombinant MuLV in female AKR/J mice may depend on enhancement of nonspecific immune or cellular immune systems (or of both) by the E. purpurea preparation.

Coronary artery bypass grafting in patients on chronic hemodialysis: surgical outcome in diabetic nephropathy versus nondiabetic nephropathy patients

BACKGROUND

The presence of diabetes mellitus adversely affects the late survival of patients undergoing coronary artery bypass grafting (CABG). The purpose of this study is to clarify the role of diabetic nephropathy on outcomes of a group of patients on chronic hemodialysis undergoing CABG.

METHODS

Between April 1984 and July 1999, 45 patients on chronic hemodialysis underwent CABG. Forty-three had conventional CABG and 2 had off-pump CABG. There were 37 males and 8 females, and the mean age was 57 years (43 to 76 years). Twenty-one patients had diabetic nephropathy (group D) and 24 had nondiabetic nephropathy (group ND). Early and late results were determined in both groups.

RESULTS

Early outcome was not significantly different between the groups. There was no hospital mortality, stroke, or requirement for prolonged mechanical ventilation (>24 hours) in either group. No patients in group D, and only 1 (4.2%) in group ND had low cardiac output syndrome. The difference in the incidence of arrhythmias (23.8% in group D and 25% in group ND), wound infections (9.5% in group D and 8.3% in group ND), and delayed tamponade (5% in group D and 12.5% in group ND) was not statistically significant. However, late results differed significantly between the two groups. Actuarial survival (Kaplan-Meier) at 5 and 9 years was 22.9% and 11.5% in group D and 89.1% and 45.7% in group ND (p = 0.01), respectively. Similarly, the cardiac event-free rate at the same intervals was 50.4% and 0% for group D and 100% and 65.8% for group ND (p = 0.001), respectively.

CONCLUSIONS

Using present technology, CABG can be done in patients on chronic hemodialysis with acceptable early mortality and morbidity. Late results in patients with diabetic nephropathy on hemodialysis are not as favorable as their nondiabetic cohort.

Relationships among facial type, buccolingual molar inclination, and cortical bone thickness of the mandible

The purpose of this study was to evaluate the relationships between different facial types, and both the buccolingual molar inclination and cortical bone thickness of the mandible. The material consisted of 31 dry skulls of modern Japanese males from the Museum of the University of Tokyo. They all demonstrated normal occlusion with minimal dental discrepancy, and without crossbite or facial asymmetry. The buccolingual inclination of the second molar (M2) in the long-faced subjects was significantly smaller than the same dimension in the average- and short-faced subjects. It was found that the teeth of long-faced subjects were more lingually inclined than those of the short-faced subjects. The cortical bone thickness of the first molar (M1) and M2 sections was thicker in short-faced subjects than in average- and long-faced subjects. The results of this study provide evidence that a significant, but complex relationship exists between structures of the mandibular body and facial types. The morphological features that relate to masticatory function and facial types are associated with the cortical bone thickness of the mandibular body, and the buccolingual inclination of the first and second molars.

Single-allele correction of the Dmo1 locus in congenic animals substantially attenuates obesity, dyslipidaemia and diabetes phenotypes of the OLETF rat

1. Whole-genome scans have identified Dmo1 as a major quantitative trait locus for dyslipidaemia and obesity in the Otsuka Long Evans Tokushima Fatty (OLETF) rat. 2. We have produced congenic rats for the Dmo1 locus through successive back-cross breeding with diabetic OLETF rats. Marker-assisted speed congenic protocols were applied to efficiently transfer chromosomal segments from non-diabetic Brown Norway (BN) rats into the OLETF background. 3. In the fourth generation of congenic animals, we observed a substantial therapeutic effect of the Dmo1 locus on lipid metabolism, obesity control and plasma glucose homeostasis. 4. We have concluded that Dmo1 primarily affects lipid homeostasis, obesity control and/or glucose homeostasis at fasting and is secondarily involved in glucose homeostasis after loading. 5. The results of the present study show that single-allele correction of a genetic defect of the Dmo1 locus can generate a substantial therapeutic effect, despite the complex polygenic nature of type II diabetic syndromes.

Role of the renal kallikrein-kinin system in the development of salt-sensitive hypertension

The role of the renal kallikrein-kinin system in the development of salt-sensitive hypertension was studied using mutant kininogen-deficient Brown-Norway Katholiek (BN-Ka) rats, which generate no kinin in their urine, and other hypertensive rat models. It was found that ingestion of a low sodium diet or infusion of NaCl in doses slightly above 0.15 M caused hypertension and sodium accumulation in erythrocytes and the cerebrospinal fluid of kininogen-deficient BN-Ka rats. Development of hypertension in the deoxycorticosterone-acetate-salt model was completely prevented by administration of a newly discovered inhibitor, ebelactone B, of carboxypeptidase Y-like exopeptidase (an urinary kininase). The urinary kallikrein excretion of spontaneously hypertensive rats was lower than that of Wistar Kyoto rats at 4 weeks of age and did not increase by administration of furosemide, a diuretic agent, although approximately 50% of the diuretic action of this agent was dependent upon the renal kallikrein-kinin system in normal rats. In conclusion, the renal kallikrein-kinin system works as a safety valve for excess sodium intake.

Adaptive cytoprotection mediated by prostaglandin I(2) is attributable to sensitization of CRGP-containing sensory nerves

BACKGROUND & AIMS

The phenomenon by which the gastric mucosa is protected in response to mild irritants has been called adaptive cytoprotection, a mechanism believed to be related to production of endogenous prostaglandins (PGs). We tested whether PGs generated by mild irritant prevent injury through the release of calcitonin gene-related peptide (CGRP) from the sensory nerves using prostanoid receptor-knockout mice.

METHODS

The stomach was doubly cannulated and perfused with 1 mol/L NaCl or 50% ethanol. CGRP levels in the perfusate were determined by enzyme immunoassay, and the injured area was estimated at the end of perfusion.

RESULTS

Preperfusion with mildly hypertonic saline (1 mol/L NaCl) increased generation of gastric PGE(2) and PGI(2) and reduced ethanol-induced mucosal damage. Exposure of ethanol after 1 mol/L NaCl increased intragastric CGRP levels from 166 +/- 27 to 713 +/- 55 pg/2 min (n = 4, P < 0.05), and the protective action of 1 mol/L NaCl was inhibited by indomethacin treatment. CGRP antagonist blocked 1 mol/L NaCl-induced protective effect. Intragastric perfusion of 50% ethanol after administration of PGI(2), but not of PGE(2), increased CGRP levels. Application of 1 mol/L NaCl to IP receptor-knockout mice (IP(-/-)) did not elicit the protective effects seen in the wild-type on ethanol-induced gastric mucosal lesions. Protective effect of 1 mol/L NaCl was observed in EP3 receptor-knockout mice (EP3(-/-)). CGRP level during ethanol perfusion was not increased in IP(-/-) but was increased in EP3(-/-) and wild-type counterparts after preperfusion of 1 mol/L NaCl.

CONCLUSIONS

These results indicate that the endogenous PGI(2) generated by 1 mol/L NaCl may have a protective role in gastric mucosal injury through enhancement of CGRP release from gastric mucosa. This mechanism may explain the adaptive cytoprotection observed after treatment with mild irritants.

Quantitative trait loci for lipid metabolism in the study of OLETF x (OLETF x Fischer 344) backcross rats

1. The Otsuka Long-Evans Tokushima Fatty (OLETF) rat is a model of type II diabetes with accompanying dyslipidaemia and obesity. 2. To define chromosomal intervals associated with obesity (abdominal fat weight and plasma leptin levels), dyslipidaemia (plasma triglyceride, cholesterol and free fatty acids) and hyperglycaemia (plasma glucose levels), we have performed genome-wide quantitative traits loci (QTL) analyses of 115 male OLETF x (OLETF x Fischer 344) backcross animals at 16 weeks of age. 3. The Diabetes Mellitus OLETF type I (Dmo1) locus on rat chromosome 1 showed statistically significant involvement in elevations of plasma levels of triglycerides (P = 4.87 x 10(-6) at D1Rat90) and total cholesterol (P = 1.16 x 10(-5) at D1Rat306). 4. No other loci produced significant linkage to these observed phenotypes. 5. These analyses have confirmed the importance of Dmo1 in lipid homeostasis at younger ages as well as during overt diabetes, which appears later. Thus, alterations at the Dmo1 locus are a major risk factor for pathogenesis in the strain, a finding that agrees with physiological studies that indicate a role for dyslipidaemia in the type II diabetic syndrome of OLETF rats.