Enhancement of methoxamine-induced contractile responses of rat ventricular muscle in streptozotocin-induced diabetes is associated with alpha1A adrenoceptor upregulation

AIM

To clarify the time-related changes in cardiac function and the mechanism underlying the cardiac dysfunction present in diabetes mellitus, we studied mechanical responses induced by alpha(1)- and beta-adrenoceptors, the Ca(2+)-entry promoter Bay K 8644- and ryanodine (an agent known to inhibit Ca(2+) release from the sarcoplasmic reticulum) in papillary muscles from streptozotocin (STZ)-induced diabetic and age-matched control rats.

METHODS

Male Wistar rats received a single injection of STZ (60 mg kg(-1)) via the tail vein to induce diabetes. For the mechanical studies, papillary muscle preparations were suspended in an organ bath and isometric contractions were measured in 1-, 4-, and 10-week STZ-induced diabetic and age-matched control rats.

RESULTS

In 1-week diabetic rats, the contractions induced by isoproterenol, methoxamine and Bay K 8644 were unchanged (vs. age-matched controls). In 4-week diabetic rats, (a) the isoproterenol- and Bay K 8644-induced contractions were impaired, (b) sensitivity to ryanodine was reduced, whereas (c) the methoxamine-induced contraction was unchanged. In 10-week diabetic rats, the isoproterenol- and Bay K 8644-induced contractile responses were impaired and the sensitivity to ryanodine was reduced, but in sharp contrast the methoxamine-induced contraction was enhanced. Both the mRNA level for the alpha(1A) adrenoceptor (but not the alpha(1B) or alpha(1D) mRNAs) and alpha(1A) adrenoceptor protein were increased in 10-week diabetic rats (vs. age-matched controls).

CONCLUSION

These results suggest that impairments of beta-adrenergic and Ca(2+)-handling mechanisms occur early in the development of cardiomyopathy in STZ-induced diabetic rats, and that this is followed by augmentation of alpha(1A) adrenoceptor-mediated inotropy due to alpha(1A) adrenoceptor upregulation.

Mechanisms underlying lysophosphatidylcholine-induced potentiation of vascular contractions in the Otsuka Long-Evans Tokushima Fatty (OLETF) rat aorta

BACKGROUND AND PURPOSE

The effect of lysophosphatidylcholine (LPC) on aortic contractions in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a type 2 diabetic model, was studied.

EXPERIMENTAL APPROACH

Using OLETF rats and control (Long Evans Tokushima Otsuka (LETO)) rats, the effects of LPC on the contractions induced by high-K(+) (10-40 mM), UK14,304 (10 approximately 100 nM; a selective alpha(2)-adrenoceptor agonist) and sodium orthovanadate (SOV; 10 microM approximately 3 mM) in endothelium-denuded aortae were compared. Aortic ERK activity and the mRNA expression for GPR4 (a putative LPC receptor) were also measured.

KEY RESULTS

OLETF rats exhibited (vs. age-matched LETO rats): (1) greater potentiation of high-K(+)-induced contraction by 10 microM LPC - a potentiation attenuated by 10 microM genistein, protein tyrosine kinase (PTK) inhibitor, (2) greater potentiation of UK14,304 (10 approximately 100 nM)-induced contractions by LPC (1 microM approximately 10 microM) - a potentiation attenuated by 10 microM genistein, 50 microM tyrphostin A23 (PTK inhibitor) or 10 microM PD98059 (MEK 1/2 inhibitor), (3) greater basal and LPC (1 microM)-induced ERK activities, (4) greater basal and 100 nM UK14,304-stimulated ERK2 activities in both the absence and presence of 10 microM LPC, (5) greater SOV (10 microM approximately 3 mM)-induced contractions, (6) greater potentiation of SOV-induced contractions by 10 microM LPC - a potentiation suppressed by 10 microM PD98059 or 10 microM genistein, (7) upregulation of GPR4 mRNA.

CONCLUSIONS AND IMPLICATIONS

These results suggest that the LPC-induced potentiation of contractions in the OLETF rat aorta may be attributable to increased PTKs or ERK activity and/or to receptor upregulation.

Spontaneous rupture of a left gastroepiploic artery aneurysm in a patient with autosomal-dominant polycystic kidney disease

Autosomal-dominant polycystic kidney disease (ADPKD) has been known to be associated with a variety of vascular diseases. We present a hemodialysis patient with ADPKD who died of a massive intraperitoneal hemorrhage caused by the spontaneous rupture of a left gastroepiploic artery aneurysm. A 64-year-old male was admitted to our hospital with acute upper abdominal pain and hemorrhagic shock. An abdominal angiography showed three aneurysms and the source of hemorrhage was assumed to be the left gastroepiploic artery aneurysm. The patient died of severe metabolic acidosis and disseminated intravascular coagulation (DIC) on the second hospital day. At autopsy, there was massive bleeding into the abdominal cavity, and pathological examination of the left gastroepiploic artery aneurysm revealed a dissecting aneurysm. This is the first case describing a rupture of a gastroepiploic aneurysm in a patient with ADPKD.

Comparison of the intubating laryngeal mask airway and laryngeal tube placement during manual in-line stabilisation of the neck

We compared the placement of the laryngeal tube (LT) with the intubating laryngeal mask airway (ILMA) in 51 patients whose necks were stabilised by manual in-line traction. Following induction of anaesthesia and neuromuscular blockade, the LT and ILMA were inserted consecutively in a randomised, crossover design. Using pressure-controlled ventilation (20 cmH(2)O inspiratory pressure), we measured insertion attempts, time to establish positive-pressure ventilation, tidal volume, gastric insufflation, and minimum airway pressure at which gas leaked around the cuff. Data were compared using Wilcoxon signed-rank tests; p < 0.05 was considered significant. Insertion was found to be more difficult with the LT (successful at first attempt in 16 patients) than with the ILMA (successful at first attempt in 42 patients, p < 0.0001). Time required for insertion was longer for the LT (28 [23-35] s, median [interquartile range]) than for the ILMA (20 [15-25] s, p = 0.0009). Tidal volume was less for the LT (440 [290-670] ml) than for the ILMA (630 [440-750] ml, p = 0.013). Minimum airway pressure at which gas leak occurred and incidence of gastric insufflation were similar with two devices. In patients whose necks were stabilised with manual in-line traction, insertion of the ILMA was easier and quicker than insertion of the LT and tidal volume was greater with the ILMA than the LT.

The impact of subject/respondent characteristics on a proxy-rated quality of life instrument for the Japanese elderly with dementia

The development of a quality of life (QL) instrument for evaluating quality of services requires extensive validation. This study examines the impact of subject/respondent characteristics on a newly developed quality of life instrument for the Japanese elderly with dementia (QLDJ) as a part of the validity examination. In the QLDJ, QL is defined as a three-dimensional construct: 'interacting with surroundings', expressing self', and 'experiencing minimum negative behaviors'. Thus the QLDJ is a multi-dimensional, 24-item instrument, and it is answered by a proxy, the formal caregiver (respondent) because the elderly with severe dementia cannot be directly interviewed. Altogether 623 elderly persons experiencing dementia from 37 institutions (e.g., nursing homes, day care centers) in Japan were assessed using the QLDJ by their formal caregivers. In addition to the levels of dementia and independence in activities of daily living, factors such as gender of the elderly person and respondent, elderly person's age, participation in recreational activities, qualification of the respondent were significantly associated with 'interacting with surroundings' and 'expressing self'. The levels of dementia and independence as well as qualification of the respondent were associated with 'experiencing minimum negative behaviors'. Possible reasons for these associations and how to deal with them are discussed. Careful control for those factors is needed when the QLDJ is used in future research.

Endogenous prostaglandin I2 regulates the neural emergency system through release of calcitonin gene related peptide

BACKGROUND

We previously reported that endogenous prostaglandin I(2), generated by a mild irritant, sensitised calcitonin gene related peptide (CGRP) containing sensory nerves and facilitated the release of CGRP and gastric mucosal protection against ethanol. Administration of capsaicin also inhibited ethanol induced gastric mucosal injury through immediate release of CGRP from primary sensory neurones, which is termed the neural emergency system. In the present study, we tested whether endogenous prostaglandin I(2) also modulates the cytoprotective action of capsaicin using prostaglandin I receptor knockout mice (IP(-/-)).

METHODS

The stomachs of IP(-/-) or their wild-type counterparts (IP(+/+)), anaesthetised with urethane (1.225 g/kg), were doubly cannulated from the oesophageal and duodenal sides, and the gastric mucosa was perfused (1 ml/min) with physiological saline. Perfusate was changed to 50% ethanol alone, or 50% ethanol containing capsaicin (16 approximately 1600 micro M). The injured area was estimated at the end of each perfusion experiment. In some animals, CGRP-(8-37), a CGRP antagonist (0.3 mg/kg), or indomethacin (1 mg/kg) was intravenously injected before perfusion of 50% ethanol containing capsaicin.

RESULTS

Capsaicin inhibited the injured area in a dose dependent manner. Fifty per cent ethanol containing capsaicin (480 micro M) immediately increased intragastric levels of CGRP although 50% ethanol alone did not. The protective action of capsaicin (480 micro M) against ethanol was completely abolished by intravenous injection of CGRP-(8-37). Indomethacin also inhibited the protective action of capsaicin, and this was accompanied by reduced levels of intragastric CGRP. Intragastric levels of prostaglandin E(2) were not increased by capsaicin treatment but those of 6-keto-prostaglandin F(1alpha), a metabolite of prostaglandin I(2), were markedly increased. No protective action of capsaicin was observed in IP(-/-) which lacked the ability to increase intragastric CGRP levels in response to ethanol containing capsaicin. The CGRP content of the stomach from untreated IP(-/-) did not differ from those in IP(+/+). Capsaicin (160 micro M) together with intragastric perfusion of beraprost sodium (PGI(2) analogue, 2.5 micro g/ml) showed enhanced protection against ethanol induced injury. This enhanced protection was completely blocked by intravenous injection of CGRP-(8-37).

CONCLUSIONS

The present results suggest that endogenous prostaglandin I(2) enhances the protective action of the capsaicin mediated neural emergency system against ethanol induced gastric mucosal injury through enhancement of CGRP release.

Gap function with point nodes in borocarbide superconductor YNi2B2C

To determine the superconducting gap function of YNi2B2C, the c-axis thermal conductivity kappa(zz) was measured in H rotated in various directions. The angular variation of kappa(zz) in H rotated within the ab plane shows a peculiar fourfold oscillation with narrow cusps. The amplitude of this fourfold oscillation becomes very small when H is rotated conically around the c axis with a tilt angle of 45 degrees. These results provide the first compelling evidence that the gap function has point nodes located along the a and b axes. This unprecedented gap structure challenges the current view on the pairing mechanism.

Nomogram for individualizing supplementary iron doses during erythropoietin therapy in haemodialysis patients

AIMS

An adequate iron supplement is crucial not only for prompt erythropoiesis but also for the restoration of tissue iron reserves in haemodialysis patients receiving recombinant human erythropoietin (r-HuEPO). An attempt was made to establish a comprehensive nomogram that allows individualization of intravenous (i.v.) iron doses according to patients' body weights, the initial status of tissue iron reserves and desired increases in haemoglobin levels.

MATERIALS AND METHODS

Clinical and laboratory data retrieved from 95 haemodialysis patients who received r-HuEPO with or without iron supplements for at least 12 weeks were used to construct the nomogram. It was assumed that the administered iron was either incorporated into newly synthesized haemoglobin and tissue iron reserves or eliminated from the body at a constant rate. Tissue iron reserves of the patients were estimated by serum ferritin levels using van Wyck's equation (Kidney Int., 1989, 35, 712). The rate of iron loss in the patients was estimated by the data obtained from 15 of the above patients who exhibited stable haemoglobin levels but decreases in serum ferritin levels with no iron supplements. The validity of the equation was ascertained by comparing the measured serum ferritin levels at the end of r-HuEPO therapy and those predicted by the nomogram. The proposed nomogram was then validated prospectively in 24 haemodialysis patients to determine whether the nomogram-recommended iron doses would increase both haemoglobin and serum ferritin levels within 12 weeks.

RESULTS

The mean (+/-SD) iron loss of haemodialysis patients was calculated to be 10.5 +/- 7.4 mg/week. There was a significant correlation (r=0.77, P < 0.001) between the measured serum ferritin levels, an index of tissue iron reserves, at the end of r-HuEPO therapy and those predicted by the equations used for formulating the nomogram. The prospective study indicated that the nomogram-recommended supplementary iron doses attained haemoglobin and serum ferritin levels of > 95 g/L and >100 microg/L in 79 and 50% of the patients, respectively, within 12 weeks.

CONCLUSION

The present nomogram may be useful for individualizing supplementary i.v. iron doses for haemodialysis patients undergoing r-HuEPO therapy.

Survey of residual solvents in natural food additives by standard addition head-space GC

Residual levels of 12 solvents in 87 natural food additives (66 samples of food colours, 19 samples of natural antioxidants and two natural preservatives) collected between 1997 and 1999 were determined by automated head-space GC using FID, with a porous-polymer (PLOT) column. Calibration curves were prepared by the method of standard addition. Confirmation was by manually injected head-space GC using mass spectrometric detection. 1,2-Dichloroethane was found in turmeric colour (natural food colour) collected in 1997 at the concentrations of 8.6 microg g(-1), but was not found in samples collected in 1998 and 1999. Hexane was found in three samples of dunaliella carotene (11, 72 and 75 microg g(-1)), and in chlorophyll at 93 microg g(-1) (both natural food colours). Acetone was found in turmeric colour, annatto colour, dunaliella carotene, kaoliang colour, cacao colour at a concentration between 8.7 and 42 microg g(-1) (all natural food colours).

Cycloprodigiosin hydrocloride suppresses tumor necrosis factor (TNF) alpha-induced transcriptional activation by NF-kappaB

Cycloprodigiosin hydrochloride (cPrG.HCl) obtained from a marine bacterium Pseudoalteromonas denitrificans induces apoptotic cell death in various cancerous cell lines. cPrG.HCl alone caused a little cytotoxicity in HeLa cells, but it enhanced the apoptotic process progressively when co-administered with tumor necrosis factor (TNF)alpha. Here we studied the effect of cPrG.HCl on TNFalpha-induced activation of the transcription factor nuclear factor kappaB (NF-kappaB). Luciferase gene reporter assays revealed that cPrG.HCl potently suppressed the TNFalpha- and the phorbol myristate acetate-induced activation of NF-kappaB. The suppression occurred in the presence of imidazole, indicating that it was not related to the intracellular acidification resulting from the intrinsic H(+)/Cl(-) symporter activity of cPrG.HCl. cPrG.HCl inhibited neither the TNFalpha-induced phosphorylation and degradation of inhibitor of nuclear factor-kappaB, nor the subsequent nuclear translocation and DNA binding of NF-kappaB. cPrG.HCl also suppressed NF-kappaB-enhanced gene expression induced by Rac1, Cdc42, MEKK1, inhibitor of nuclear factor-kappaalpha (IKKalpha), IKKbeta, and a subunit of NF-kappaB, p65. These results indicate that cPrG.HCl suppresses NF-kappaB-dependent gene expression through the inhibition of transcriptional activation.

Mechanisms underlying attenuated contractile response of aortic rings to noradrenaline in fructose-fed mice

We hypothesized that an impairment of endothelial dysfunction and an increased response to alpha-adrenoceptor agonists may occur in fructose-fed, insulin-resistant mice. The aim of the present study was to assess the relationship between endothelial dysfunction and agonist-induced contractile responses in such mice. The acetylcholine-induced relaxation was significantly attenuated in streptozotocin-diabetic and fructose-fed mice. The contractile response to noradrenaline was significantly weaker than the control in fructose-fed but not in streptozotocin-diabetic mice; treatment with N(G)-nitro-L-arginine effectively restored this response. Incubating aortic rings with noradrenaline increased the NO(x) [nitrite (NO(2)(-)) and nitrate (NO(3)(-))] level and this level was significantly higher in fructose-fed mice than in control mice. Clonidine induced a dose-dependent relaxation in aortic rings pre-contracted with prostaglandin F(2alpha) that was completely abolished by N(G)-nitro-L-arginine; this relaxation was markedly enhanced in fructose-fed mice. In both control and fructose-fed mice, the clonidine-induced relaxation was significantly attenuated and the noradrenaline-induced contraction augmented by pertussis toxin. These results suggest that endothelial function is attenuated in both fructose-fed and streptozotocin-diabetic mice. It is suggested that the decreased noradrenaline contractile response in fructose-fed mice (compared to both controls and streptozotocin-diabetic mice) may be due to an increase in nitric oxide formation mediated by endothelial GTP-binding-coupled alpha(2)-adrenoceptors.

Cancer-associated myofibroblasts possess various factors to promote endometrial tumor progression

Myofibroblastic invasion associated with malignant epithelial cells of endometrial cancer as well as other cancers is often found in the interstitium. To assess the myofibroblastic-epithelial interaction, frozen sections from a total of 10 endometrial cancers with or without invasive myofibroblasts were immunohistochemically examined. Interestingly, the invasive myofibroblasts adjacent to malignant epithelial cells showed frequently intensive positive staining of several growth factors such as vascular endothelial growth factor (VEGF), insulin-like growth factor I, and epidermal growth factor, the cognate receptors such as Fetal liver kinase-1/Kinase Insert Domain-containing receptor/VEGF receptor-2, fms-like tyrosine kinase-1/VEGF receptor-1, and epidermal growth factor receptor, several cell cycle regulators such as cyclins and cyclin dependent kinases, and estrogen receptor alpha. Moreover, we indicated that the majority of the myofibroblasts as well as cancer epithelial cells are proliferating because of their positive staining of proliferating cell nuclear antigen and Ki-67. Furthermore, the myofibroblasts were also positive of hypoxia-inducible factor 1 alpha, which is a marker protein of hypoxia, probably followed by activation of VEGF-Flk-1 and VEGF-fms-like tyrosine kinase-1 signals, which could initiate angiogenesis. These findings suggest directly that the myofibroblasts might participate in the progression of tumor cells in terms of cancer cell growth stimulation and also activated initiation of angiogenesis.

Primary extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue type in the CNS

Extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) type has been reported in various internal organs. Here a case is reported of MALT lymphoma developing in the cerebellopontine (CP) angle in a patient with Sjogren syndrome, and the concept of MALT lymphoma of the CNS is introduced. Pathologically, the tumor showed inflammatory features of reactive lymphocytic infiltration with follicle formation, but there were slightly atypical lymphocytes and plasmacytes with B-cell markers. These cells invaded reactive follicles, showing follicular colonization, and showed aberrant expression indicating their neoplastic nature. A review of the literature revealed eight cases of MALT lymphoma originating from the dura mater and one from the CP angle. The average age of patients was 50 years (range 28-66 years), and all patients were female. The tumors were slow to develop and the patients were cured after surgical removal and/or additional therapies. It is proposed that MALT lymphoma should be considered as a differential diagnosis of inflammatory pseudotumor of the CNS.

Crystallographic approach to identification of cyclin-dependent kinase 4 (CDK4)-specific inhibitors by using CDK4 mimic CDK2 protein

Genetic alteration of one or more components of the p16(INK4A)-CDK4,6/cyclin D-retinoblastoma pathway is found in more than half of all human cancers. Therefore, CDK4 is an attractive target for the development of a novel anticancer agent. However, it is difficult to make CDK4-specific inhibitors that do not possess activity for other kinases, especially CDK2, because the CDK family has high structural homology. The three-dimensional structure of CDK2, particularly that bound with the inhibitor, has provided useful information for the synthesis of CDK2-specific inhibitors. The same approach used to make CDK4-specific inhibitors was hindered by the failure to obtain a crystal structure of CDK4. To overcome this problem, we synthesized a CDK4 mimic CDK2 protein in which the ATP binding pocket of CDK2 was replaced with that of CDK4. This CDK4 mimic CDK2 was crystallized both in the free and inhibitor-bound form. The structural information thus obtained was found to be useful for synthesis of a CDK4-specific inhibitor that does not have substantial CDK2 activity. Namely, the data suggest that CDK4 has additional space that will accommodate a large substituent such as the CDK4 selective inhibitor. Inhibitors designed to bind into this large cavity should be selective for CDK4 without having substantial CDK2 activity. This design principle was confirmed in the x-ray crystal structure of the CDK4 mimic CDK2 with a new CDK4 selective inhibitor bound.

Studies on new platelet aggregation inhibitors 1. Synthesis of 7-nitro-3,4-dihydroquinoline-2(1H)-one derivatives

A series of 6-cyclic aliphatic amino-7-nitro-3,4-dihydroquinoline-2(1H)-ones were prepared and tested for platelet aggregation inhibitory effect, cardiotonic activity and chronotropic activity. These compounds appeared to show selective inhibitory activity against platelet aggregation. Among them, 6-(4-ethoxycarbonylpiperidino)-7-nitro-3,4-dihydroquinoline-2(1H)-one (22f) showed the most potent inhibitory activity and high selectivity. A divergent synthetic route to 6-cyclic aliphatic amino-7-nitro-3,4-dihydroquinoline-2(1H)-one derivatives has also been investigated.