Role of endogenous nitric oxide generation in the regulation of vascular tone and reactivity in small vessels as investigated in transgenic mice using synchrotron radiation microangiography

Nitric oxide (NO) produced by endothelial NO synthase (eNOS) plays a central role in regulation of vascular tone and reactivity. The purpose of this study is to clarify the basal tone and microvascular reactivity in eNOS-overexpressing transgenic (Tg) mice in vivo with a microangiography system using monochromatic synchrotron radiation (SR). The mouse femoral artery was cannulated, nonionic contrast media was injected, and microangiography was performed in hindlimbs of mice. Serial images of the small blood vessels (diameter <200 microm) were recorded by the SR microangiography system. At basal conditions, the diameter of tibial arteries in eNOS-Tg mice was larger than that of wild-type mice (179 +/- 8 versus 132 +/- 8 microm; P < 0.01). l-NAME treatment decreased the vessel diameter and canceled the difference in vessel diameters between two genotypes. Acetylcholine- and sodium nitroprusside-induced relaxations of small vessels were significantly reduced in Tg mice compared with wild-type mice (35.0 +/- 9.4 versus 61.6 +/- 6.7%, 85.0 +/- 10.2 versus 97.3 +/- 6.7% of the maximum relaxation, respectively). Our data provide the evidence that overproduced NO from endothelium reduces vascular tone and plays a pivotal role in regulation of vascular tone in small vessels. Furthermore, the reduced NO-mediated relaxation in small vessels of eNOS-Tg mice is demonstrated for the first time in vivo. SR microangiography allows us to evaluate the reactivity in small-sized vessels and appears to be a powerful tool for assessing the microvascular circulation in vivo.

Total synthesis of (S)-(+)-curcudiol, and (S)-(+)- and (R)-(-)-curcuphenol

A highly enantioselective synthesis of the versatile chiral synthons possessing one stereogenic center, (S)- and (R)-4-aryl-5-hydroxy-(2E)-pentenoate (3) was achieved based on the enzymatic reaction of (+/-)-3 with commercially available lipases MY-30 or OF-360 from Candida rugosa. Application of (S)-3 and (R)-3 to the total syntheses of(S)-curcuphenol (1), (S)-curcudiol (2), and (R)-curcuphenol (1), respectively, is described.

Frequency and clinical characteristics of dilated cardiomyopathy caused by desmin gene mutation in a Japanese population

AIMS

Dilated cardiomyopathy is partly caused by a mutation of some cytoskeletal or nuclear envelope proteins. It has been confirmed recently that a missense mutation of the gene encoding desmin, a cytoskeletal protein, can cause dilated cardiomyopathy. This study was aimed at elucidating the frequency and clinical characteristics of dilated cardiomyopathy caused by desmin mutation.

METHODS AND RESULTS

We examined 265 Japanese patients with dilated cardiomyopathy (217 sporadic cases and 48 probands of familial dilated cardiomyopathy). The exon 8 of the desmin gene, the critical region for the pathogenesis of dilated cardiomyopathy, was analysed by polymerase chain reaction, single-strand conformation polymorphism and sequencing. The same missense mutation (Ile451Met) as reported previously was detected in three patients (1.1%). All these patients were male and sporadic, and more likely to be accompanied by characteristics such as younger age at diagnosis, lower fractional shortening and ejection fraction than each mean value of sporadic cases. The chronological changes in cardiac function were inconsistent in the three patients.

CONCLUSION

The missense mutation (Ile451Met) of the desmin gene can be the genetic cause of dilated cardiomyopathy, although with very low frequency. The ages at diagnosis were younger and the cardiac function had deteriorated further than general cases of sporadic dilated cardiomyopathy.

[Critical role for cell cycle regulators in androgen receptor function]

Androgen plays an important role in the growth of prostate cancer, but the molecular mechanism that underlies development of resistance to antiandrogen therapy remains unknown. Cyclin E has now been shown to increase the transactivation activity of the human androgen receptor (AR) in the presence of its ligand dihydrotestosterone. The enhancement of AR activity by cyclin E was resistant to inhibition by the antiandrogen 5-hydroxyflutamide. Cyclin E was shown to bind directly to the AB domain of the AR, and to enhance its AF-1 transactivation function. These results suggest that cyclin E functions as a coactivator of the AR, and that aberrant expression of cyclin E in tumors may contribute persistent activation of AR function, even during androgen ablation therapy.

[The trend of childhood bacterial meningitis in Japan (1997.7-2000.6)]

We surveyed the epidemiology of purulent meningitis in pediatrics for 3 years between July 1997 and June 2000 in Japan and obtained the following results. The number of cases of purulent meningitis was 428, which was equivalent of 1.1-1.7 children out of 1,000 hospitalized those in pediatrics per year. The age-distribution for the infections was the highest under 1 year of age and it decreased as the age increased. Under 1 year of age, the highest distribution was observed in one month of age and under 1 month of age, the highest distribution was observed in 7 days of or younger ages. Haemophilus influenzae was the most common pathogen causing the infections, followed by Streptococcus pneumoniae, group B streptococcus, and Escherichia coli. Relationship between causing pathogens and age-distribution was as follows: group B streptococcus and E. coli were major pathogens under 4 months of age and H. influenzae and S. pneumoniae were major pathogens over 3 months of age. Susceptibility tests performed at each facility demonstrated that 25.3% of H. influenzae isolates and 38.7% of S. pneumoniae isolates were drug-resistant. Analysis of resistant genes for H. influenzae and S. pneumoniae isolates, which were stored and sent, demonstrated higher rates of resistance than those observed in susceptibility tests. These results suggest that the increase in insufficient efficacy of usual treatment with combination of ampicillin and cefotaxime is predictable against the infections. Therefore, the treatment for the infections should be reconsidered.

[The efficacy of a comprehensive smoking cessation class, combined with nicotine patch and gum replacement therapy]

A six-month comprehensive smoking cessation class was conducted in our hospital, and the results were evaluated after one year. To increase the rate of smoking cessation, a smoking cessation support team composed of a medical doctor, a pharmacist, nurses, a registered dietitian, and a physical therapist was formed. The team provided specialized lectures and comprehensive group counseling programs every two weeks for the first two months and every month for the next four months. Each participant's expired carbon monoxide concentration and body weight were measured at every attendance. The participant continued with beneficial behavioral treatment for smoking cessation for six months, with nicotine replacement therapy (NRT) for the first eight weeks. The protocol of our NRT consisted of both the routine use of nicotine patches (Nicotinell TTS) and the rescue use of nicotine gum (Nicorette). We first ascertained each participant's degree of nicotine dependence, using the Fagerström Tolerance Questionnaire score, and daily nicotine intake was estimated by a detailed questionnaire. We then divided the participants into two NRT groups according to their nicotine dependence. The higher nicotine dependence group consisted of those whose Fagerström Tolerance Questionnaire score was more than 5 points or whose estimated nicotine intake was more than 10 mg/day. This group they used Nicotinell TTS 30 (TTS 30) for the first four weeks, TTS 20 for the next two weeks, and TTS 10 for the last two. In the lower dependence group. TTS 20 and TTS 10 were each given for four weeks. Nicotine gum use was restricted to 4 pieces a day for the first week and reduced by one per day each subsequent week. As a result, there was an 81.3% smoking cessation rate after eight weeks, 70.3% after six months, and 58.2% after one year. In conclusion, two courses of routine nicotine patch use, with the addition of restricted rescue use of nicotine gum, can produce better longterm abstinence results than previously reported NRTs, suggesting that this may be one of the best ways to cease smoking. We also emphasize that intensive group counseling programs and lectures supported by doctors and medical teams, as well as a continuing behavioral treatment component, may be indispensable for enhancing longterm sustained abstinence rates.

Metabolic changes in human CD36 deficiency displayed by glucose loading

Previous in vitro studies have shown that CD36 participates in cellular fatty acid (FA) uptake. In vivo evidence for a physiologic role of CD36 in this process is poor and mostly obtained in animals. To examine the metabolic role of human CD36, we performed a glucose loading test for normals (n = 16) and subjects with CD36 deficiency, both Type I (n = 5) and Type II (n = 16). After 30 min, FA levels had fallen by 60.1% in normals but by only 31.7% in Type II deficiency (P <0.01 vs. normals) and 16.5% in Type I deficiency which remained significantly higher than the other two groups out to 2 h. Further, changes in triglyceride and glucose metabolism were observed in the both types of CD36 deficiency. Impaired fast FA clearance by muscle and consequently increased hepatic FA uptake seem to underlie these changes. We conclude that human CD36 deficiency causes systemic metabolic changes.

Hypoglycemic effect of S(-)-hydroxyhexamide, a major metabolite of acetohexamide, and its enantiomer R(+)-hydroxyhexamide

A short-lasting hypoglycemic effect was observed when S(-)-hydroxyhexamide (S-HH), a major metabolite of acetohexamide, and its enantiomer R(+)-hydroxyhexamide (R-HH), were administered orally to rats. Since the reductive metabolism of acetohexamide is known to be reversible in rats, oral administration of R-HH may exhibit the hypoglycemic effect through the generation of acetohexamide. However, oral administration of R-HH to rabbits, in spite of their inability to oxidize R-HH to acetohexamide, caused a significant decrease and increase, respectively, of plasma glucose and insulin levels. Furthermore, both S-HH and R-HH were found to stimulate the secretion of insulin from hamster HIT T15 cells (pancreatic beta-cells). These results provide further evidence that both R-HH and S-HH exhibit a significant hypoglycemic effect.

Sinusoidal efflux of taurocholate is enhanced in Mrp2-deficient rat liver

PURPOSE

It has been shown that plasma concentration and urinary excretion of bile acids is elevated under the cholestatic/ hyperbilirubinemic conditions. Previously, it was demonstrated that the plasma concentration of bile acids was elevated in the multidrug resistance-associated protein 2 (Mrp2)-deficient rats. The purpose of the present study was to compare the sinusoidal efflux clearance of taurocholate (TC) between Mrp2-deficient Eisai hyperbilirubinemic rats (EHBR) and normal rats.

METHOD

Hepatic disposition of the [3H]TC was examined in the perfused liver. Apparent efflux clearance (PSnet, eff) of [3H]TC from hepatocytes to outflow across the sinusoidal membrane was defined as the amount of [3H]TC excreted into the outflow from the liver divided by hepatic AUC of [3H]TC. Additionally, influx clearance (PSinf) was also determined by multiple indicator dilution method because PSnet, eff is also affected by PSinf.

RESULTS

PSnet, eff was significantly higher in EHBR than that in Sprague-Dawley (SD) rats (16.6 +/- 1.7 vs. 6.1 +/- 1.3 microL/min/g liver, P < 0.01). In contrast, PSinf was comparable between SD rats and EHBR. Kinetic analysis suggested that the intrinsic clearance for the efflux of [3H]TC across the sinusoidal membrane in EHBR was higher than that in SD rats (10.4 +/- 1.0 v.s. 23.3 +/- 1.7 microL/min/g liver, P < 0.01).

CONCLUSIONS

Enhanced sinusoidal efflux of TC in EHBR may be related to the altered disposition of bile acids in the mutant rats. Because Mrp3 transports TC and its expression is induced on the basolateral membrane of Mrp2-deficient rats, the enhanced sinusoidal efflux of TC in EHBR may be accounted for, at least partially, by the increased expression of Mrp3.

The reaction of (4R,5R)- and (4S,5S)-4,5-epoxy-2(E)-hexenoates and secondary amines

A reaction of methyl (4R,5R)-4,5-epoxy-2(E)-hexenoate 1 with N-benzylmethylamine gave a diastereomerically pure methyl (4R,5R)-4,5-epoxy-(3S)-N-benzylmethylamino hexanoate 6 and methyl (4S,5R)-4-N-benzyl-methylamino-5-hydroxy-2(E)-hexenoate 7. The former was chemoenzymatically converted to (-)-osmundalactone 11, which is an aglycone of osmundalin. On the other hand, the directly conjugated addition of dimethylamine to methyl (4S,5S)-4,5-epoxy-2(E)-hexenoate 1 followed by treatment with MeOH at 40 degrees C exclusively provided methyl (4R,5S)-4-dimethylamino-5-hydroxy-2(E)-hexenoate 16, which was converted into L-(-)-forosamine 18.

Characterization of bile acid transport mediated by multidrug resistance associated protein 2 and bile salt export pump

Biliary excretion of certain bile acids is mediated by multidrug resistance associated protein 2 (Mrp2) and the bile salt export pump (Bsep). In the present study, the transport properties of several bile acids were characterized in canalicular membrane vesicles (CMVs) isolated from Sprague--Dawley (SD) rats and Eisai hyperbilirubinemic rats (EHBR) whose Mrp2 function is hereditarily defective and in membrane vesicles isolated from Sf9 cells infected with recombinant baculovirus containing cDNAs encoding Mrp2 and Bsep. ATP-dependent uptake of [(3)H]taurochenodeoxycholate sulfate (TCDC-S) (K(m)=8.8 microM) and [(3)H]taurolithocholate sulfate (TLC-S) (K(m)=1.5 microM) was observed in CMVs from SD rats, but not from EHBR. In addition, ATP-dependent uptake of [(3)H]TLC-S (K(m)=3.9 microM) and [(3)H]taurocholate (TC) (K(m)=7.5 microM) was also observed in Mrp2- and Bsep-expressing Sf9 membrane vesicles, respectively. TCDC-S and TLC-S inhibited the ATP-dependent TC uptake into CMVs from SD rats with IC(50) values of 4.6 microM and 1.2 microM, respectively. In contrast, the corresponding values for Sf9 cells expressing Bsep were 59 and 62 microM, respectively, which were similar to those determined in CMVs from EHBR (68 and 33 microM, respectively). By co-expressing Mrp2 with Bsep in Sf9 cells, IC(50) values for membrane vesicles from these cells shifted to values comparable with those in CMVs from SD rats (4.6 and 1.2 microM). Moreover, in membrane vesicles where both Mrp2 and Bsep are co-expressed, preincubation with the sulfated bile acids potentiated their inhibitory effect on Bsep-mediated TC transport. These results can be accounted for by assuming that the sulfated bile acids trans-inhibit the Bsep-mediated transport of TC.

Serotonin-induced hypercontraction through 5-hydroxytryptamine 1B receptors in atherosclerotic rabbit coronary arteries

BACKGROUND

Augmented vasoconstriction to serotonin (5-hydroxytryptamine [5-HT]) in atherosclerotic vessels plays a crucial role in the development of myocardial ischemia. We investigated mechanisms for serotonin-evoked hypercontraction in atherosclerotic rabbit coronary arteries.

METHODS AND RESULTS

Contractile responses to serotonergic agents of endothelium-denuded coronary arteries from control and Watanabe heritable hyperlipidemic rabbits (WHHL) were examined. WHHL coronary arteries exhibited hypercontraction to 5-HT(1)-receptor agonists; the constrictor threshold concentrations and E:D(50) to serotonin, 5-carboxamidotryptamine, and sumatriptan in WHHL were significantly lower, and the E:(max) in WHHL to these agents were increased 55% to 59% above those of the control. Serotonin-evoked contractions in both groups were inhibited by GR127935 (5-HT(1B/1D) antagonist; 0.1 to 1 nmol/L) and pertussis toxin but not by ketanserin (5-HT(2) antagonist; 0.01 to 1 micromol/L), suggesting that the hypercontraction is most likely mediated by 5-HT(1B/1D) receptors through a pertussis toxin-sensitive pathway. Furthermore, simultaneous measurements of [Ca(2+)](i) and isometric tension of fura-2-loaded arteries revealed that the hypercontraction was concomitant with the augmented elevation of [Ca(2+)](i) in the smooth muscle. The 5-HT(1B) mRNA levels in WHHL coronary arteries increased to 2.5-fold over those in control arteries, whereas neither 5-HT(1D) nor 5-HT(2A) mRNA was detected in either group.

CONCLUSIONS

Atherosclerotic rabbit coronary arteries exhibited the enhancement in contraction and Ca(2+) mobilization in response to serotonin. The 5-HT(1B) receptor, which is upregulated by atherosclerosis, most likely mediates the augmenting effects of serotonin.

Decreased longevity in Japanese men, associated with low-molecular-weight apolipoprotein(a) phenotypes

Lipoprotein(a) [Lp(a)] is an established risk factor for atherosclerosis. High plasma Lp(a) concentrations are associated with low-molecular-weight (LMW) apolipoprotein(a) (apo a) phenotypes, which raises the question of whether LMW apo a phenotypes occur less frequently in the elderly. To assess this possibility, we studied apo A phenotype and allele frequencies in Japanese subjects > or = 80 years old (men:women = 40:34) in comparison with those <80 years old (men:women = 221:296). Significantly fewer LMW phenotypes and LMW alleles were observed in > or = 80 year old men compared with those < 80 years old: 2.5% versus 16.1% for the LMW phenotype frequency and 1.3% versus 9.7% for the LMW allele frequency (P<0.05, Fisher's exact probability test). Similar differences were not found in the women. Consistent with this, plasma Lp(a) concentrations were significantly lower in the men > or = 80 years old than in the younger group. These results indicate that LMW apo a phenotypes are associated with a shorter lifespan in men but not in women, possibly reflecting the higher susceptibility of men to atherosclerosis.

Lysophosphatidylcholine increases the secretion of matrix metalloproteinase 2 through the activation of NADH/NADPH oxidase in cultured aortic endothelial cells

Matrix metalloproteinases (MMPs) play a pivotal role in angiogenesis, atherogenesis, vascular remodeling after vascular injury, and instability of atherosclerotic plaque. The present study was undertaken to investigate the effect of lysophosphatidylcholine, a major component of oxidized low density lipoprotein (LDL), on the regulation of MMPs in cultured bovine aortic endothelial cells (BAECs). Furthermore, we explored the potential role of oxidative stress in the regulation of MMP. LPC increased the secretion of gelatinolytic activity, as well as, protein of MMP-2 from BAECs. The stimulation of BAEC with superoxide increased the production of MMP-2 and it also induced its activation. Electron spin resonance (ESR) with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as spin trap agent demonstrated that lysophosphatidycholine (LPC) induced generation of reactive oxygen (ROS) species from BAECs. The inhibition of NADH/NADPH oxidase, one of the potential sources of superoxide in endothelial cells, attenuated the effect of LPC. Our findings suggest that LPC might activate the endothelial NADH/NADPH oxidase to enhance superoxide production, and it might, in turn, enhance MMP-2 induction.

Morphological evaluation of the baboon hind limb muscles based on relative weight

Morphological features of the hind limb muscles reflect the muscular function correlating with the locomotion. In this study, the muscles of the baboon hind limb were weighed and the relative muscle weights were compared with those of the human lower extremity. In the baboon, the biceps femoris was the largest (11.60%) and the vastus lateralis (10.67%) was placed second. The gluteus medius (8.55%) among the hip muscles and the gastrocnemius (4.38%) among the leg muscles were predominant in each segment. The relative weights of the gluteus medius and the biceps femoris were especially larger in the baboon than in the human, while the gluteus maximus and the soleus were larger in the human. The baboon gluteus medius and biceps femoris chiefly generate the propulsive power during quadrupedal locomotion and the human soleus is essential for the erect bipedalism.

Sexual dimorphism of the motoneurons in the human spinal cord

There have been few morphometric studies on the size of the motoneurons of the human spinal cord. The purpose of the present study is to report the differences in the size of the motoneurons between males and females in the human spinal cord. We examined numbers and transverse cell body areas of the motoneurons of the anterior horn using 16 male and 21 female human spinal cords at levels C5 and L3. The sizes of the motoneurons were larger in males than in females, but their numbers were practically the same. These results can be of great importance in setting standard values for the understanding of morphological and functional correlations.

[Comparison of the morphology and the reactivity of Chlamydia pneumoniae isolated in north-Kanto Area, Ibaraki Prefecture, Japan]

To compare the morphology among Chlamydia pneumoniae (C. pneumoniae), strain TW183 and strains which were isolated in the area of Kasumigaura, Ibaraki from 1992 to 1995. C. pneumoniae were infected on HL cell monolayers and cultured in 5% CO2 at 35.5 degrees C for about 60 hrs. The cells were harvested and fixed with 2.5% glutaraldehyde, and then the regular procedure for observation of Chlamydia in inclusion by transmission electron microscope was performed. Immunoblot assay was carried out by using highly and partially purified C. pneumoniae TW183 and 4 isolates with partial purification as antigens. The results were as follows: the shape of TW183 and the isolates included pear and round shapes, respectively. Immunoblotting profiles were the same in terms of band-formation patterns with the serum from a patient infected with C. pneumoniae. These results may indicate that the round shape of C. pneumoniae elementary body (EB) is predominantly pandemic in Japan, although pear-shaped EBs of C. pneumoniae were found in the neighboring prefecture of Chiba.

Carvedilol improves endothelium-dependent dilatation in patients with coronary artery disease

OBJECTIVE

Flow-mediated, endothelium-dependent dilatation (FMD) of the coronary and peripheral circulation is impaired by increased oxidative stress in patients with coronary artery disease (CAD). Carvedilol is a novel beta-blocker that also shows an antioxidant effect in vitro. However, the effect of carvedilol on endothelial dysfunction associated with established coronary atherosclerosis has not been examined in the clinical setting.

METHODS

We studied 29 patients with CAD, including 17 with recent myocardial infarction and 12 with stable effort angina pectoris. Nineteen patients received carvedilol (10 with infarction and 9 with angina), and 10 were treated with placebo (7 with infarction and 3 with angina). We also studied 13 age- and sex-matched control subjects. Brachial FMD during reactive hyperemia and nitroglycerin-induced, endothelium-independent dilatation were assessed by high-resolution ultrasound.

RESULTS

FMD was smaller in patients with CAD compared with controls, although nitroglycerin-induced dilatation was similar. Carvedilol significantly improved FMD after long-term treatment (5. 1% +/- 0.4% at baseline to 7.8% +/- 0.3% after 4 months; P <.01) but not after short-term treatment (5.1% +/- 0.4% at baseline to 5.0% +/- 0.7% after 2 hours). Placebo therapy had no effect on endothelial dysfunction. Neither carvedilol nor placebo had an effect on nitroglycerin-induced dilatation after short- and long-term treatment. Long-term carvedilol therapy also significantly decreased the plasma level of thiobarbituric acid-reactive substances compared with placebo (carvedilol, 5.8 +/- 0.4 nmol/mL to 4.6 +/- 0.3 nmol/mL, P <.01; placebo, 5.9 +/- 0.4 nmol/mL to 5.8 +/- 0.4 nmol/mL, P = not significant).

CONCLUSION

These findings suggest that the improvement of endothelial function by carvedilol may be caused by its antioxidant activity.