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N Harada

Publications and source records attributed to N Harada.

At least 37 records · Page 2Linked to original sources
PubMed2004

Restoration of male sexual behavior by adult exogenous estrogens in male aromatase knockout mice.

We previously found that male aromatase knockout (ArKO) mice that carry a targeted mutation in exons 1 and 2 of the CYP19 gene and as a result cannot aromatize androgen to estrogen show impaired sexual behavior in adulthood. To determine whether this impairment was due to a lack of activation of sexual behavior by estradiol, we studied here male coital behavior as well as olfactory investigation of sexually relevant odors in male ArKO mice following adult treatment with estradiol benzoate (EB) or dihydrotestosterone propionate (DHTP). Again, we found that gonadally intact ArKO males show pronounced behavioral deficits affecting their male coital behavior as well as their olfactory investigation of volatile body odors but not that of soiled bedding. Deficits in male coital behavior were largely corrected following adult treatment with EB and the androgen DHTP, suggesting that estradiol has prominent activational effects on this behavior. By contrast, adult treatment with EB to either castrated or gonadally intact ArKO males did not stimulate olfactory investigation of volatile body odors, suggesting that this impairment may result from a lack of proper organization of this behavior during ontogeny due to the chronic lack of estrogens. In conclusion, the present studies suggest that the behavioral deficits in sexual behavior in male ArKO mice result predominantly from a lack of activation of the behavior by estrogens. This is in contrast with earlier pharmacological studies performed on rats and ferrets that have suggested strong organizational effects of estradiol on male sexual behavior.

Analysis of Variance↗
PubMed2004

Activated protein C reduces stress-induced gastric mucosal injury in rats by inhibiting the endothelial cell injury.

BACKGROUND AND OBJECTIVE: Activated protein C (APC) is a natural anticoagulant with anti-inflammatory activity. APC inhibits neutrophil activation through inhibition of tumor necrosis factor (TNF)-alpha production. Such anti-inflammatory activity of APC has recently been shown to be critical in the treatment of patients with severe sepsis. We previously demonstrated that activated neutrophils play a crucial role in the development of stress-induced gastric mucosal injury. Thus, inhibition of neutrophil activation by APC should reduce endothelial cell damage, maintain gastric blood flow, and lessen gastric mucosal injury. In the present study, we examined this possibility by using a rat model of water-immersion restraint stress (WIRS)-induced gastric mucosal injury. METHODS AND RESULTS: Gastric mucosal injury was observed 4 h after WIRS, without increases in gastric mucosal levels of either myeloperoxidase activity or TNF-alpha, but with significant increases in plasma levels of TNF-alpha 1 h after WIRS. Intravenous administration of APC (100 micro g kg-1) significantly reduced WIRS-induced gastric mucosal injury by inhibiting decrease in gastric mucosal blood flow. Administration of APC also inhibited both the decrease in gastric tissue levels of 6-keto-prostaglandin F1alpha and the increase in gastric mucosal micorvascular permeability in animals subjected to WIRS. Furthermore, APC inhibited WIRS-induced increases in plasma levels of TNF-alpha. Neither active site-blocked factor Xa, which is a selective inhibitor of thrombin generation, nor active site-blocked APC had any effect on these events. Intraperitoneal administration of anti-rat TNF-alpha antibody produced effects similar to those of APC. CONCLUSIONS: The observations in the present study strongly suggest that APC reduces stress-induced gastric mucosal injury by inhibiting the decrease in gastric mucosal blood flow through attenuation of the activated neutrophil-induced endothelial cell injury via inhibition of TNF-alpha production. In addition, we show that serine protease activity of APC, rather than its anticoagulant activity, is critical for the protective mechanism(s) by which TNF-alpha production could be inhibited.

Animals↗
PubMed2004

Relationships between aromatase activity in the brain and gonads and behavioural deficits in homozygous and heterozygous aromatase knockout mice.

The present study was carried out to determine whether aromatase knockout (ArKO) mice are completely devoid of aromatase activity in their brain and gonads and to compare aromatase activity in wild-type and ArKO mice, as well as in heterozygous (HET) mice of both sexes that were previously shown to display a variety of reproductive behaviours at levels intermediate between wild-type and ArKO mice. Aromatase activity was extremely low, and undetectable by the tritiated water assay, in homogenates of the preoptic area-hypothalamus of adult wild-type mice, but was induced following a 12-day treatment with testosterone. The induction of aromatase activity by testosterone was significantly larger in males than in females. Even after 12 days exposure to testosterone, no aromatase activity was detected in the brain of ArKO mice of either sex whereas HET mice showed intermediate levels of activity between ArKO and wild-type. Aromatase activity was also undetectable in the ovary of adult ArKO females but was very high in the wild-type ovary and intermediate in the HET ovary. In wild-type mice, a high level of aromatase activity was detected on the day of birth even without pretreatment with testosterone. This neonatal activity was higher in males than in females, but females nevertheless appear to display a substantial level of oestrogen production in their brain. Aromatase activity was undetectable in the brain of newborn ArKO males and females and was intermediate between wild-type and ArKO in HET mice. In conclusion, the present study confirms that ArKO mice are unable to synthesize any oestrogens, thereby validating the ArKO mouse as a valuable tool in the study of the physiological roles of oestradiol. In addition, it demonstrates that the intermediate behaviour of HET mice presumably reflects the effect of gene dosage on aromatase expression and activity, that aromatase activity is sexually differentiated in mice during the neonatal period as well as in adulthood and, finally, that the neonatal female brain produces substantial amounts of oestrogens that could play a significant role in the sexual differentiation of the female brain early in life.

Animals↗
PubMed2003

Forebrain Fos responses to reproductively related chemosensory cues in aromatase knockout mice.

Sexually relevant pheromonal cues are detected by the vomeronasal system which includes the posterodorsal part of the medial amygdala, the posteromedial part of the bed nucleus of the stria terminalis and the medial preoptic area. Copulatory behavior is impaired in mice lacking functional aromatase, the enzyme converting testosterone into estradiol. In this study, we used male aromatase knockout (ArKO) mice to investigate the role of aromatase in the differentiation and activation of preference for male- or female-related odorants. Moreover, using Fos immunoreactivity as a marker of neuronal activation we investigated the ability of sex-related pheromonal cues to activate the vomeronasal system. Both gonadally intact wild-type and ArKO mice preferred to investigate urine from females. The lack of estrogens did not reverse odor preferences, i.e. male ArKO mice did not show a preference for male odors. Exposure to soiled bedding from females induced Fos-protein in the posterodorsal part of the medial amygdala, in the posteromedial part of the bed nucleus of the stria terminalis, and in the periventricular part of the medial preoptic area of both the genotypes. Exposure to soiled bedding from intact males induced Fos in the posterodorsal part of the medial amygdala in wild-type mice and in the periventricular medial preoptic area in wild-type and ArKO mice. These results suggest that preference for female-related odors and the Fos-mediated activation of the vomeronasal system do not rely on estradiol. Furthermore, sensitivity to female chemosensory cues and copulatory behavior are uncoupled in this knockout model.

Analysis of Variance↗
PubMed2003

Factors influencing autonomic nervous function during cold-water immersion test in patients with hand-arm vibration syndrome.

OBJECTIVES: Factors influencing autonomic nervous function in patients with hand-arm vibration syndrome (HAVS) in response to cold-water immersion test with different water temperatures and immersion times were investigated in the summer and winter seasons. METHODS: Fourteen HAVS patients with vibration-induced white finger (VWF) and 14 healthy control subjects individually age-matched to the patients consented in writing and participated in this study. Patients and controls immersed their left hands in water at 10 degrees C for 10 min and at 15 degrees C for 3 min in summer and in winter in a room with temperature maintained at 21+/-1 degrees C. Electrocardiographic (ECG) data were recorded during the test period and the R-R intervals were analyzed with a fast Fourier transformation (FFT) program. Percentage of very low frequency (VLF%; indicator of both sympathetic and parasympathetic nervous function, and function of rennin-angiotensin system), low frequency (LF%; indicator of both sympathetic and parasympathetic nervous function), high frequency (HF%; indicator of parasympathetic nervous function), and LF/HF ratio (indicator of sympathetic nervous function) were calculated. The results by three-way analysis of variance (ANOVA) were reported elsewhere. In the present study, repeated measures ANOVA was used to re-analyze the factors of data measurement time (time factor) and group (group factor), and their interaction for each test method (water at 10 degrees C for 10-min immersion time; water at 15 degrees C for 3-min immersion time) in summer and winter. RESULTS: The HF% of HAVS patients tended to be lower than that of healthy controls throughout the cold-water immersion tests except for during tests involving water at 10 degrees C for 10-min immersion in summer. The group factor for HF% was statistically significant with an exception during the test involving water at 10 degrees C and 10-min immersion time in summer. The time factor for HF% was statistically significant with an exception during the test involving water at 15 degrees C and 3-min immersion time in winter. CONCLUSIONS: The findings of the present study indicated lower cardiac parasympathetic activity in HAVS patients than in healthy controls, especially in winter. The response of the autonomic nervous system to cold stimulation was to some extent more clearly observed during the immersion test with water at 10 degrees C and 10-min immersion time than during the immersion test with water at 15 degrees C and 3-min immersion time. The results revealed by three-way analysis in a previous study were similar to those in the present study with data analysis by repeated measures ANOVA.

Analysis of Variance↗
PubMed2003

p53 and PTEN/MMAC1 mutational analysis of the small-intestinal cancer.

A 66-year-old female, suffering from small-intestinal cancer underwent resection of the small intestine. Genome DNAs were extracted from the patient's blood and small-intestinal cancer and were subjected to a polymerase chain reaction-single strand conformation polymorphism and nucleotide sequence analysis for exons of the p53 and PTEN/MMAC1 genes to search for any mutations. The sequence analysis revealed a point mutation of the p53 codon 93 in the cancer DNA; however, no mutation of the PTEN/MMAC1 gene was observed in either the blood or cancer DNA. The p53 mutation, therefore, seems to be related to tumour progression of small-intestinal cancer; however, no relationship was found between the PTEN/MMAC1 gene and the small-intestinal cancer.

Aged↗
PubMed2003

Breast carcinoma in women over the age of 85: distinct histological pattern and androgen, oestrogen, and progesterone receptor status.

AIMS: The pathogenesis of breast carcinoma in very elderly women is of interest, because oestrogen levels are likely to be extremely low during the development of the disease. In an effort to understand the pathogenesis of breast carcinoma in these women, this study was undertaken to compare the histological patterns and hormone receptor status of breast carcinomas arising in very elderly and younger women. METHODS AND RESULTS: Thirty-seven breast carcinomas from women over the age of 85 years at the time of their operation were examined histologically and compared with those from a large group of premenopausal women. The proportions of mucinous carcinoma and apocrine carcinoma were significantly greater in older women. The expression of steroid hormone receptors was studied immunohistochemically. Androgen receptor-positive carcinomas were significantly more frequent among older women, whereas progesterone receptor-positive carcinomas were significantly less frequent. There was no statistically significant difference in oestrogen receptor-alpha or -beta expression between the tumours from both groups. CONCLUSION: Breast carcinomas in women over the age of 85 years have a different morphological spectrum from carcinomas in younger age groups and may have different pathogenesis mechanisms that may be more dependent on androgen and androgen receptor interaction. Differences from the results of the other studies are discussed.

Adenocarcinoma↗
PubMed2003

The aromatase knockout (ArKO) mouse provides new evidence that estrogens are required for the development of the female brain.

The classic view of sexual differentiation is that the male brain develops under the influence of testicular secretions, whereas the female brain develops in the absence of any hormonal stimulation. However, several studies have suggested a possible role of estradiol in female neural development, although they did not provide unequivocal evidence that estradiol is indispensable for the development of the female brain and behavior. As a result, the hypothesis subsequently languished because of the lack of a suitable animal model to test estrogen's possible contribution to female differentiation. The recent introduction of the aromatase knockout (ArKO) mouse, which is deficient in aromatase activity because of a targeted mutation in the CYP19 gene and therefore cannot aromatize androgen to estrogen, has provided a new opportunity to reopen the debate of whether estradiol contributes to the development of the female brain. Female ArKO mice showed reduced levels of lordosis behavior after adult treatment with estradiol and progesterone, suggesting that estradiol is required for the development of the neural mechanisms controlling this behavior in female mice. The neural systems affected may include the olfactory systems in that ArKO females also showed impairments in olfactory investigation of odors from conspecifics. Thus, the classic view of sexual differentiation, that is, the female brain develops in the absence of any hormonal secretion, needs to be re-examined.

Animals↗
PubMed2002

Sexual partner preference requires a functional aromatase (cyp19) gene in male mice.

Sexual motivation, sexual partner preference, and sexual performance represent three different aspects of sexual behavior that are critical in determining the reproductive success of a species. Although the display of sexual behavior is under strict hormonal control in both sexes, the relative roles of androgen and estrogen receptors in activating the various components of male sexual behavior are still largely unknown. A recently developed mouse model that is deficient in estradiol due to targeted disruption of exons 1 and 2 of the Cyp19 gene (aromatase knockout (ArKO) mice) was used here to analyze the role of estradiol in the control of all three aspects of male sexual behavior. When tested in a Y-maze providing volatile olfactory cues, male ArKO mice did not show a preference for the odors from an estrous female over those from an intact male, whereas wild-type (WT) and heterozygous (HET) males clearly preferred to sniff estrous odors. When provided with visual and olfactory cues, male ArKO mice also failed to show a preference for an estrous female when given a choice between an estrous female and an empty arm. However, sexual partner preferences of male ArKO mice were not sex-reversed: they did not prefer to investigate an intact male over an estrous female or empty arm. Thus, male ArKO mice seemed to have general deficits in discriminating between conspecifics by using olfactory and visual cues. Male coital behavior was also severely impaired in male ArKO mice: they displayed significantly fewer mounts, intromissions, and ejaculations than WT and HET males. Latencies to first mount or intromission were also significantly longer in ArKO males compared to WT and HET males, in addition to them showing less interest in investigating olfactory and visual cues in a Y-maze, suggesting that they were sexually less motivated. However, three out of seven male ArKO mice were capable of siring litters provided they were housed with a female for a prolonged period of time. In conclusion, aromatization of testosterone to estradiol appears to be essential for sexual motivation and sexual partner preference. By contrast, estradiol may play only a limited role in the expression of male coital behaviors.

Animals↗
PubMed2002

Evaluation of thermal cycling and mechanical loading on bond strength of a self-etching primer system to dentin.

OBJECTIVE: The aim of this study was to evaluate the in vitro durability and fracture modes of the tooth-resin interface following thermal cycling, fatigue load cycling (FLC) and micro-tensile bond strength testing (MTBS). METHODS: Twenty-four human molars were divided into two groups. In group A, coronal dentin was ground flat with #600-grit SiC paper, Clearfil Linerbond.2V (LB.2V) adhesive was applied and a crown fabricated with Clearfil AP-X resin composite. Samples were loaded in the FLC simulator and thermal cycle device. In group B, Class I cavities were prepared with a diamond bur and the cavity restored with LB.2V/AP-X. Samples were simultaneously subjected to FLC and thermal cycling. After storage of the specimens in water for 1 week, MTBS tests were performed, and fracture modes examined by SEM. RESULTS: For group A, MTBS were approximately 40 MPa with cohesive failures in the bonding resin of all specimens. Neither thermal nor mechanical stressing altered bond strengths on flat dentin surfaces. In group B, MTBS in the unstressed control group was 21 MPa with cohesive failures in the resin. As both thermal and mechanical stresses increased, there was a significant decrease in bond strength (16 MPa, P<0.05) and the fractures were seen in the resin-dentin interface and hybrid layer. SIGNIFICANCE: Surface preparation, C-factor, cavity depth, the dentin substrate and character of the smear layer strongly influence the bond strength values after thermal and fatigue loading. The FLC simulator in combination with MTBS testing provides meaningful in vitro evaluation of dentin bonding durability.

Acid Etching, Dental↗
PubMed2002

Changes in the arginine-vasopressin immunoreactive systems in male mice lacking a functional aromatase gene.

In male rodents, the arginine-vasopressin-immunoreactive (AVP-ir) neurones of the bed nucleus of the stria terminalis (BNST) and medial amygdala are controlled by plasma testosterone levels (decreased after castration and restored by exogenous testosterone). AVP transcription in these nuclei is increased in adulthood by a synergistic action of the androgenic and oestrogenic metabolites of testosterone and, accordingly, androgen and oestrogen receptors are present in both BNST and medial amygdala. We used knockout mice lacking a functional aromatase enzyme (ArKO) to investigate the effects of a chronic depletion of oestrogens on the sexually dimorphic AVP system. Wild-type (WT) and ArKO male mice were perfused 48 h after an i.c.v. colchicine injection and brain sections were then processed for AVP immunocytochemistry. A prominent decrease (but not a complete suppression) of AVP-ir structures was observed in the BNST and medial amygdala of ArKO mice by comparison with the WT. Similarly, AVP-ir fibres were reduced in the lateral septum of ArKO mice and but not in the medial preoptic area, a region where the AVP system is not sexually dimorphic in rats. No change was detected in the supraoptic and suprachiasmatic nuclei. However, a decrease in AVP-ir cell numbers was however, detected in one subregion of the paraventricular nucleus. These data support the hypothesis that the steroid-sensitive sexually dimorphic AVP system of the mouse forebrain is mainly under the control of aromatized metabolites of testosterone.

Animals↗