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Biomedical subjects

Minoru Irahara

Publications and source records attributed to Minoru Irahara.

At least 37 records · Page 2Linked to original sources
PubMed2005

A reduction in intraovarian arterial blood flow resistance after ovulation is necessary to achieve pregnancy in natural cycle.

PURPOSE: Color Doppler imaging permits the accurate localization of vessels and high-frequency pulsed Doppler ultrasonography has improved the resolution of flow velocity waveforms. In this study, intraovarian arterial blood flow before and after follicle rupture in the natural cycle was examined using transvaginal color flow Doppler imaging and changes in intraovarian arterial resistance in relation to the outcome of infertility treatment was analyzed. METHODS: In a prospective study, 227 spontaneous cycles in 118 infertile patients who were undergoing infertility treatment at the division of Reproductive Medicine in our center were recruited in this study. The impedance to flow in intraovarian vessels was measured by means of transvaginal color flow Doppler imaging during the periovulatory period in the natural cycle of all patients. The pulsatility index (PI) of intraovarian arterial blood flow and pregnancy rate was evaluated. RESULTS: On the basis of PI values before and after follicular rupture, 227 cycles were classified into severely decreased (113 cycles) and not-severely decreased groups (114 cycles). The pregnancy rate per cycle in the severely decreased group was 18.6% (21/113), significantly higher than that in the not-severely decreased group (7/114; 6.1%, p = 0.004). The miscarriage rate was similar in the two groups. CONCLUSIONS: A reduction in intraovarian blood vessel resistance is necessary to achieve pregnancy in a natural cycle.

Blood Flow Velocity↗
PubMed2005

Effects of postmenopausal hormone therapy every day and every other day on lipid levels according to difference in body mass index.

OBJECTIVE: The objective of this study was to determine the effects of postmenopausal estrogen and progestogen therapy (EPT) every day and every other day on lipid levels, particularly triglyceride (TG) levels, according to difference in body mass index (BMI). DESIGN: Ninety-nine postmenopausal women (mean age, 53.9 +/- 5.6 years; mean BMI, 22.8 +/- 2.8 kg/m) were randomly treated with EPT every other day or every day for 1 year. Fifty women received oral administration of 0.625 mg of conjugated equine estrogen (CEE) and 2.5 mg of medroxyprogesterone acetate (MPA) every other day, and 49 women received oral administration of 0.625 mg of CEE and 2.5 mg of MPA every day. Blood samples were collected at baseline and after 1 year of therapy for measurement of fasting TG, total cholesterol, high-density lipoprotein-cholesterol (HDL-C), and apolipoproteins. Data from 88 of the 99 postmenopausal women were used for analysis. RESULTS: In women whose BMI was 25 kg/m or higher, TG levels during EPT every day increased by 26.8%, while TG levels during EPT every other day decreased by 12.3%. There was a significant (P < 0.05) difference between percentage changes in TG during EPT every day and every other day. In women whose BMI was less than 25 kg/m, TG levels during EPT every day increased by 21.7%, while during EPT every other day TG levels did not change. The mean levels of estradiol during EPT every day in women whose BMI was less than 25 kg/m and in women whose BMI was 25 kg/m or higher were 28.5 and 38.7 pg/mL, respectively, the difference between these levels was significant (P < 0.01). On the other hand, there was no significant difference between levels of estradiol during EPT every other day in these two BMI groups. CONCLUSIONS: Triglyceride levels during EPT every day with conventional doses of CEE and MPA increased more in overweight and obese postmenopausal women in association with increased estrogen levels.

Administration, Oral↗
PubMed2004

Human spermatozoa capacitated with progesterone or a long incubation show accelerated internalization by an alkyl ether lysophospholipid.

OBJECTIVE: To evaluate changes that occur in sperm plasma membranes during capacitation, the internalization of [(3)H]lyso-platelet activating factor ([(3)H]lyso-PAF) across the plasma membrane of human spermatozoa was measured as a function of incubation time or exposure to progesterone (P). DESIGN: In vitro cell culture study using human spermatozoa. SETTING: Department of Obstetrics and Gynecology, School of Medicine, the University of Tokushima, Japan. PATIENT(S): Semen were obtained from three fertile healthy volunteers. INTERVENTION(S): The internalization of [(3)H]lyso-PAF across the plasma membranes of human spermatozoa that were incubated for an extended period or exposed to P was measured at 5, 20, 60, and 120 minutes after the addition of the phospholipid probe using the modified albumin back-exchange method. MAIN OUTCOME MEASURE(S): The percentage of capacitated and acrosome-reacted sperm and the proportion of internalization of lyso-PAF across the plasma membrane. RESULT(S): A 6-hour incubation period significantly increased the percentage of capacitated spermatozoa and the proportion of internalization of [(3)H]lyso-PAF across the plasma membrane of human spermatozoa compared with controls (capacitated spermatozoa, 20.3 +/- 10.6% vs. 8.5 +/- 1.8%; internalization 120 minutes after the addition of the phospholipid probe, 25.6 +/- 2.5% vs. 11.6 +/- 3.0%) (mean +/- SEM). Exposure to P significantly increased the percentage of capacitated spermatozoa compared with controls (19.6 +/- 6.8% vs. 11.0 +/- 2.4%) and also significantly accelerated the internalization of [(3)H]lyso-PAF compared with controls (internalization 120 minutes after the addition of the phospholipid probe, 26.2 +/- 1.8% vs. 21.4 +/- 1.1%). CONCLUSION(S): The administration of P or a long incubation increased the proportion of internalization and consequently induced capacitation in human spermatozoa.

Cell Membrane↗
PubMed2004

Sperm-immobilizing antibodies suppress an increase in the plasma membrane fluidity of human spermatozoa.

OBJECTIVE: To clarify the mechanism by which capacitation is blocked by sperm-immobilizing antibodies, changes in the plasma membrane fluidity of human spermatozoa exposed to sperm-immobilizing antibodies were evaluated. DESIGN: In vitro cell culture study using human spermatozoa. SETTING: Department of Obstetrics and Gynecology, School of Medicine, The University of Tokushima. PATIENT(S): Semen samples were obtained from four healthy, fertile volunteers. INTERVENTION(S): The internalization of [3H]lyso-platelet activating factor (lyso-PAF) across the plasma membranes of human spermatozoa, which were exposed to sperm-immobilizing antibodies (antisperm group) or not exposed (control group), was measured at 20 and 60 minutes after the addition of a phospholipid probe using the modified albumin-back extraction method. MAIN OUTCOME MEASURE(S): The percentage of internalization of [3H]lyso-PAF across the plasma membrane of human spermatozoa. RESULT(S): Although the percentages of internalization of [3H]lyso-PAF (mean +/- SE) in the antisperm and control groups 20 minutes after addition of [3H]lyso-PAF were not significantly different (6.6% +/- 1.5% and 9.2% +/- 2.1%, respectively), at 60 minutes after the addition, the percentage in the antisperm group (9.0% +/- 1.3%) was significantly lower than that in the control group (13.4% +/- 1.3%). This inhibitory effect was diminished when spermatozoa exposed to sperm-immobilizing antibodies were incubated in an antibody-free medium. CONCLUSION(S): Sperm-immobilizing antibodies suppress the increase in internalization of an alkyl ester lysophospholipid probe in plasma membranes of human spermatozoa, and this inhibitory effect is reversible. Therefore, sperm-immobilizing antibodies suppress the fluidity of the plasma membranes of human spermatozoa, thus blocking capacitation.

Antibodies↗
PubMed2003

Serum estradiol concentration as measured by HPLC-RIA and bone mineral density in postmenopausal women during hormone replacement therapy.

OBJECTIVE: To determine the relationship between the serum estradiol concentration and bone mineral density (BMD) of the lumbar spine in postmenopausal women treated with conjugated equine estrogen (CEE) and medroxyprogesterone acetate (MPA) every other day and every day. METHODS: Eighty-four postmenopausal women were randomly treated with hormone replacement therapy (HRT) every other day and every day. Forty-seven women received oral administration of 0.625 mg CEE and 2.5 mg MPA every other day, and 37 women received oral administration of 0.625 mg CEE and 2.5 mg MPA every day. BMD of the lumbar spine at 12 months and serum concentrations of estradiol and estrone at 6 and 12 months after treatment were examined. RESULTS: The estradiol concentration in subjects treated every other day showed a significant (p < 0.001) positive correlation with the percentage change in lumbar BMD, while that in subjects treated every day was not correlated with the percentage change in BMD. The differences between serum estradiol concentrations after 12 months of treatment and initial serum estradiol values in women treated every other day and every day also showed a significant (p < 0.01 and 0.05, respectively) positive correlation with percentage changes in BMD. In women treated every other day, body mass index (BMI) in the subjects in whom BMD did not increase was significantly (p < 0.01) lower than that in the subjects in whom BMD did increase. CONCLUSIONS: The serum estradiol concentration in women treated every other day has a strong positive correlation with the percentage change in lumbar BMD, but a higher estradiol concentration may be needed for women in whom BMD did not increase with HRT every other day after due consideration of individual characteristics such as BMI.

Adult↗
PubMed2003

Circulating osteoprotegerin in women during GnRH-agonist treatment and their relationships with mineral components and biomarkers of bone turnover.

A novel cytokine termed osteoprotegerin (OPG) that is also called osteoclastogenesis-inhibitory factor, which inhibits osteoclast maturation and activity, was recently isolated. In order to determine the influence of estrogen deficiency on the levels of circulating OPG in women, we studied the changes in the levels of circulating OPG in 10 Japanese women ages 25-49 (mean +/- SD, 34.0 +/- 6.9) years with endometriosis receiving gonadotropin-releasing hormone agonists (GnRH-a) therapy. We further analyzed whether the levels of circulating OPG have relations with the levels of the biomarkers of bone turnover or those of circulating mineral components in these patients during GnRH-a treatment. The patients were treated with a monthly injection of 3.75 mg leuprolide acetate depot for 6 months. In all patients, the concentrations of serum estradiol decreased after 6 months of GnRH-a treatment. The bone mineral density of the lumber spines in these patients significantly (P < 0.01) decreased (percentage change: mean +/- SD, -5.4 +/- 2.1%), while circulating OPG levels significantly (P < 0.01) increased after 6 months of treatment. The values of circulating OPG had significant correlations with those of urinary pyridinoline (r = 0.59, P < 0.01), urinary deoxypylridinoline (Dpd) (r = 0.46, P < 0.05), and serum alkaline phosphatase (r = 0.66, P < 0.01) but not with those of serum carboxy-terminal propeptide of type I procollagen during GnRH-a treatment. The values of circulating OPG also correlated significantly with those of serum calcium (Ca) and phosphorus (P) (r = 0.65 and 0.72, P < 0.01). Further analyses revealed that the percentage change in the value of circulating OPG had a significant correlation with that of urinary Dpd (r = 0.84, P < 0.01). These results suggest that circulating OPG levels rise against the increase in osteoblastic bone resorption and circulating Ca levels in the case of estrogen deficiency, possibly as a compensatory mechanism serving to limit circulating Ca levels and bone density.

Adult↗
PubMed2003

Stimulatory effect of the herbal medicine Keishi-bukuryo-gan on a cytokine-induced neutrophil chemoattractant, in rat ovarian cell culture.

PROBLEM AND METHOD OF STUDY: We investigated the effects of Keishi-bukuryo-gan, a Japanese herbal medicine, and its crude ingredients in relation to the production of cytokine-induced neutrophil chemoattractant (CINC/gro), interleukin 1beta (IL-1beta) and tumor necrosis factor alpha (TNFalpha), which are known to stimulate the secretion of CINC/gro in the ovulatory process, and the effects of Keishi-bukuryo-gan with those of Toki-shakuyaku-san, which has been shown to have an effect on the ovary. We cultured whole ovarian dispersates from immature (3-week-old) female rats with Keishi-bukuryo-gan, Toki-shakuyaku-san and crude ingredients of Keishi-bukuryo-gan. The contents of CINC/gro, IL-1beta and TNFalpha in the cultured media were determined by enzyme-linked immunosorbent assay (ELISA). RESULTS: Keishi-bukuryo-gan stimulated the secretion of CINC/gro in a dose-dependent manner, and the secretion of CINC/gro into the culture medium increased significantly at concentrations of Keishi-bukuryo-gan of 10 and 100 microg/mL (P < 0.001). The stimulatory effect of Keishi-bukuryo-gan on the production of CINC/gro is significantly (P < 0.001) stronger than that of Toki-shakuyaku-san at the same concentrations of 100 microg/mL. In addition, Keishi-bukuryo-gan stimulated the secretion of IL-1beta in a dose-dependent manner, while it did not stimulate the secretion of TNFalpha even at a concentration of 100 microg/mL. Moutan Cortex, Paeoniae Radix and Persicae Semen, which are crude ingredients of Keishi-bukuryo-gan, enhanced the secretion of CINC/gro significantly (P < 0.01) in cultured whole ovarian dispersates. CONCLUSIONS: These results show that Keishi-bukuryo-gan can stimulate the secretion of CINC/gro as well as the production of IL-1beta and that this stimulatory effect of Keishi-bukuryo-gan was significantly stronger than that of Toki-shakuyaku-san in immature rat ovarian cell culture.

Animals↗
PubMed2003

The herbal medicine Unkei-to stimulates the secretion of a cytokine-induced neutrophil chemoattractant, CINC/gro, in the rat ovarian cell culture.

PROBLEM AND METHOD OF STUDY: We investigated the ovulation-inducing effects of Unkei-to, a Japanese herbal medicine, in relation to the production of sex steroid hormones (17beta-estradiol and progesterone), cytokine-induced neutrophil chemoattractant (CINC/gro), interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) in the rat ovarian cell culture. RESULTS: Unkei-to at a concentration of 100 microg/mL significantly stimulated the secretions of 17beta-estradiol and progesterone (P < 0.01) in cultured whole ovarian dispersates. Unkei-to also enhanced the secretion of CINC/gro in a dose-dependent manner, and the secretions of CINC/gro increased significantly at concentrations of 10 and 100 microg/mL (P < 0.01). These stimulatory effects of Unkei-to on steroidgenesis and CINC/gro production are very similar to those of another Japanese herbal medicine, Toki-Shakuyaku-san. In addition, Unkei-to significantly (P < 0.01) enhanced the secretions of both IL-1beta and TNF-alpha, which are known to stimulate the secretion of CINC/gro in the ovulatory process, at concentrations of 10 and 100 microg/mL. The stimulatory effect of Unkei-to at a concentration of 100 microg/mL on IL-1beta/was significantly (P < 0.01) lower than that of Toki-Shakuyaku-san, while the stimulatory effects of these two herbal medicines at a concentration of 100 microg/mL on TNF-alpha were similar. CONCLUSIONS: These results show that Unkei-to can stimulate ovarian steroidgenesis and the ovulatory process by inducing the secretion of CINC/gro with IL-1beta and TNF-alpha in vitro. Unkei-to has stimulatory effects on both steroidgenesis and the ovulatory process in the ovary as well as a stimulatory effect on the hypothalamus-pituitary axis, and it may be useful for treating patients with ovulatory disorders.

Animals↗
PubMed2003

Hormone replacement therapy in postmenopausal women.

Hormone replacement therapy (HRT) is effective for relieving vasomotor symptoms such as hot flash and vaginal atrophy and for preventing bone loss in postmenopausal and bilaterally ovariectomized women. However, compliance with HRT was reported to be low despite the benefits of HRT. In addition, results of several recent large-scale randomized clinical trials have demonstrated that protection from cardiovascular disease is not an indication for treatment with estrogen and progestin in postmenopausal women. Recent studies have demonstrated that low-dose HRT is safe and effective for prevention of postmenopausal bone loss. Low-dose HRT has also been shown to be effective for reducing the number and severity of hot flashes, improving vaginal atrophy, and inducing favorable changes in lipids, lipoproteins and hemostatic factors. Moreover, low-dose regimens of CEE (conjugated equine estrogen) and MPA (medroxyprogesterone acetate) result in higher rates of amenorrhea and endometrial protection compared with the conventional dose of HRT. Low-dose HRT may improve the compliance rate and may be more effective than conventional-dose HRT for reducing the risk of breast cancer. On the other hand, it has been shown that transdermal estrogen treatment reduces the incidence and severity of hot flashes and that long-term treatment with transdermally administered estrogen is effective for protection against osteoporosis. Transdermal administration of estrogen is recommended in postmenopausal women with hypertriglycemia because this treatment has little effect on lipid metabolism. The serum estradiol level was reported to be closely related to estrogenic effects on various tissues. An HRT regimen should be based on the needs of each patient. Serum estradiol levels in women should be maintained at appropriate levels for benefits and not be excessively high in order to prevent side effects. Selection of the most appropriate regimen of HRT (dose, route of administration and schedule) for the needs of the individual are important factors to increase the rate of continuation with HRT.

Administration, Cutaneous↗
PubMed2002

Production of human mast cell chymase in human myometrium and placenta in cases of normal pregnancy and preeclampsia.

OBJECTIVE: To investigate whether the human mast cell chymase-endothelin-1(1-31) system was present in human myometrium, chorion and umbilical cord in normal pregnancy. METHODS: Myometrium, placenta and umbilical cord were obtained from five normal pregnant women and 10 with preeclampsia. Each tissue was stained with antibodies against hMC and ET-1(1-31). RESULTS: Routine cells were located mainly around vessels. The number of hMC-positive cells and production of ET-1(1-31) were significantly higher in myometrium from patients with severe preeclampsia compared to those from normal pregnant women. In contrast, their numbers were significantly lower in placenta and umbilical cord in patients with severe preeclampsia. CONCLUSIONS: These results suggest that the hMC-ET-1(1-31) system is active in normal pregnancy. Overproduction of hMC and ET-1(1-31) in the myometrium may be involved in the pathogenesis of severe preeclampsia, and in such cases some defense mechanism may operate in the fetus to cope with the pathological effect of the hMC-ET-1(1-31) system.

Chymases↗
PubMed2002

The obesity in bilateral ovariectomized rats is related to a decrease in the expression of leptin receptors in the brain.

We investigated the expression levels of leptin receptors in the brain of ovariectomized (OVX) rats. The mean expression level of ob mRNA in adipose tissues of OVX rats was significantly (P < 0.01) lower than that in the SHAM operation group rats, and the mean body weight of OVX rats was significantly (P < 0.01) greater than that in the SHAM group rats. However, there were no differences between serum leptin concentrations in these two groups. The mean level of leptin receptor (OB-R) mRNA expression in the brain tissue and the mean level of long form type OB-R (OB-RL) mRNA expression in the hypothalamus of the OVX rats were significantly (P < 0.05) lower than those in the SHAM group rats. These changes were cancelled by supplementation with 17 beta-estradiol in OVX rats. These results suggested that not only changes in the expression level of ob mRNA in adipose tissue and the serum leptin concentration but also changes in the OB-R mRNA in the brain are involved in the body weight increase in OVX rats and that a decrease in OB-R makes transmission of signals to suppress the amount of food intake difficult, thus leading to an increase in body weight.

Animals↗
PubMed2002

A repertoire of cytokines in human seminal plasma.

The pathophysiological significance of seminal cytokines in sperm function is still controversial. We determined the repertoire of cytokines in seminal plasma obtained from men with or without abnormalities in semen and assessed the pathophysiological significance of seminal cytokines. After conventional analysis of semen samples obtained from 86 men, levels of seminal cytokines (interleukin [IL]-1alpha, IL-2, IL-4, IL-6, IL-8, tumor necrosis factor-alpha [TNF-alpha], interferon-gamma, granulocyte colony-stimulating factor [G-CSF], macrophage CFS [M-CSF]) and granulocyte elastase were measured by an enzyme-linked immunosorbent assay. Leukocytospermia was defined as seminal plasma, which has > or =1000 ng/ml granulocyte elastase. Leukocytospermia was found in nine of 62 of the subjects in the normozoospermic group but in none of the 24 subjects showing abnormal sperm parameters (azoospermia, n=5; oligozoospermia, n=4; asthenozoospermia, n=15). The IL-8 level in the leukocytospermic group was significantly higher than those in the normal and oligozoospermic groups. IL-1alpha and TNF-alpha levels in the leukocytospermic group were significantly higher than those in the normal and asthenozoospermic groups. Although the G-CSF level in the leukocytospermic group was significantly higher than that in the normal group, high levels of M-CSF were detected in all groups. The IL-8 level was strongly correlated with IL-1alpha (r=0.935, P<0.0001) and G-CSF (r=0.916, P<0.0001) levels. Cytokines detected in seminal plasma are associated with the pathogenesis of leukocytospermia but not with the pathogenesis of asthenozoospermia and oligozoospermia.

Cytokines↗
PubMed2002

Involvement of carbohydrate molecules on zona pellucida in human fertilization.

Although the involvement of several receptors and ligand molecules in sperm-zona interaction in many species have been proposed, there has been a little analysis of the kinetics between these molecules during the interaction. In the present study, we applied the detection method using surface plasmon resonance (SPR) by a BIAcore apparatus for the analysis of the putative receptor-ligand interaction of sperm-egg binding. Mannose-BSA or [man](5)-[GlcNAc](2)-Asp was immobilized on the surface of a sensor chip. When concanavalin A (Con A) was delivered to each of two different sensor chips to evaluate their usefulness, the resonance signal after sample injection onto a [man](5)-[GlcNAc](2)-Asp-fixed chip decreased rapidly than the mannose-BSA-fixed chip. However, the amount of binding for Con A during the injection onto the [man](5)-[GlcNAc](2)-Asp-fixed chip was high. When acid sperm extracts (acid extracts) and fractions through a CM column, containing protease activity (protease fractions), were delivered to the mannose-BSA-fixed chip, the SPR signal during the injection was not obviously changed compared with that of the control. However, when sperm samples were delivered to the [man](5)-[GlcNAc](2)-Asp-fixed chip, the SPR response during the injection was enormous. These results suggest that the [man](5)-[GlcNAc](2)-Asp-fixed chip is more useful than the mannose-BSA-fixed chip for investigating the interactions with sperm extracts and that the sensitive method using SPR by a BIAcore apparatus is applicable for the analysis of the putative receptor-ligand interaction of sperm-egg binding.

Animals↗
PubMed2002

Increased production of bioactive lysophosphatidic acid by serum lysophospholipase D in human pregnancy.

Lysophosphatidic acid (LPA) is a prototype of the lysophospholipid mediator family and has multiple effects in the female reproductive system. Although several metabolic routes have been reported for intracellular formation of LPA, a unique route involving lysophospholipase D, an extracellular enzyme that produces LPA in blood and body fluids, is particularly intriguing for its agonistic role. In this study, using an assay with radioactive palmitoyl-lysophosphatidylcholine, we found that lysophospholipase D activity producing palmitoyl-LPA in human serum gradually increased during pregnancy. Elevated activity of lysophospholipase D was not caused by changes in levels of their precursors, lysophosphatidylcholines, in nonpregnant women or in pregnant women at different gestational periods. With increasing length of gestation, the elevated activity in pregnant women was found to produce increasing proportions of LPA with a palmitoyl group versus other LPAs. These results suggest that LPA formed by increased activity of lysophospholipase D in blood might participate in maintenance of pregnancy.

Adult↗
PubMed2002

Effects of leptin on gonadotropin secretion in juvenile female rat pituitary cells.

OBJECTIVE: Leptin is an adipocyte-derived hormone, which is the product of the obese gene and it is thought to play important roles in pubertal development and maintenance of reproductive function in the female. In a study using adult male or female rats, it was found that leptin stimulated the secretion of gonadotropin directly from the pituitary in a dose-related manner. However, there is no study in juvenile female rats before puberty. METHODS: In this study, we cultured pituitary cells from 4-, 6- and 8-week-old female Wistar rats with leptin (0-10(-7)mol/l) and gonadotropin-releasing hormone (GnRH) (0 or 10(-8) mol/l). Basal or GnRH-stimulated secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), and their synthesis within cells were determined by radioimmunoassay (RIA). RESULTS: Leptin induced bell-shaped dose--response curves of basal LH and FSH secretion from cultured cells of every age-group of rats studied. The most effective concentration of leptin on the basal secretion of LH and FSH from 6- and 8-week-old cultured pituitary cells was 10(-10) mol/l. This leptin concentration was consistent with circulating physiological serum leptin levels at each age. As for juvenile 4-week-old pituitary cells, the most effective concentration was 10(-11) mol/l which was lower than that of 6- and 8-week-old rats. It was consistent with the circulating serum leptin levels of 4-week-old rats. Also, the synthesis and the GnRH-stimulated secretion of LH and FSH were effectively controlled by leptin at concentrations similar to the serum leptin levels of given ages. CONCLUSIONS: Leptin induced pituitary cells to synthesize and secrete both LH and FSH regardless of the presence or absence of GnRH. The concentration of leptin that induced the greatest synthesis and secretion of gonadotropins from pituitary cells changed around the pubertal period. The most effective leptin concentrations in each experiment were similar to the physiological serum leptin level at each animal age. These results indicate that leptin stimulates gonadotrophs not only in the pubertal and the mature period but also in the juvenile period before puberty. It is also conceivable that leptin may modulate the sensitivity of gonadotrophs until the appearance of GnRH stimulation, and may be the factor that brings about puberty onset.

Animals↗
PubMed2002

Human papilloma virus (HPV) and cervical cancer.

Epidemiological and experimental studies have clearly shown that high-risk HPV infection is the main etiologic factor for cervical cancer. Recent studies have indicated that the E6 and E7 gene products play a critical role in cervical carcinogenesis. The E6 and E7 products interfere with the p53 and pRB functions, respectively, and deregulate the cell cycle. The HPV DNA is integrated into the host's chromosomes with disruption of the E2 gene. This disruption promotes the expression of E6 and E7, leading to the accumulation of DNA damage and the development of cervical cancer. The study of the immune response against HPV has been hampered by the lack of a cell culture system for the virus. A breakthrough was made by the discovery that a major capsid protein L1 self-assembles into virus-like particles (VLP) when expressed in eukaryotic systems. Clinical trials of VLP-based vaccines are in progress, and DNA vaccines for the HPV surface protein genes are under development. The E7 and E6 oncoproteins are attractive targets for cancer immunotherapy because their expression is required to maintain the oncogenicity of cervical cancer cells. Cancer immunotherapy for cervical cancer with vaccinations of E7 peptides or dendritic cell-based immunotherapy is moving toward clinical trials.

Adult↗
PubMedDate not supplied

Undercarboxylated osteocalcin concentration in postmenopausal women receiving hormone therapy daily and on alternate days.

OBJECTIVE: Undercarboxylated osteocalcin (ucOC) is a sensitive marker of vitamin K status. The authors examined the difference in serum ucOC concentrations in postmenopausal women receiving hormone therapy (HT) daily and on alternate days, and assessed the association between ucOC and triglyceride concentrations, which are related to the transport of vitamin K. DESIGN: Seventy-three postmenopausal women were recruited for this study. Thirty-seven women received 0.625 mg of conjugated equine estrogens (CEE) and 2.5 mg of medroxyprogesterone acetate (MPA) daily, and 36 women received 0.625 mg of CEE and 2.5 mg of MPA on alternate days. The concentrations of serum ucOC, bone turnover markers, lipid profiles, and hormones were measured before and after 12 months of HT. RESULTS: The ucOC concentration in women taking HT daily was significantly (P < 0.01) lower than that in women taking HT on alternate days. Serum ucOC concentrations during HT showed a significant (P < 0.01) inverse correlation with estradiol concentrations during HT. Serum estradiol concentrations during HT showed a significant (P < 0.01) positive correlation with triglyceride concentrations during HT. Furthermore, ucOC concentrations during HT showed a significant (P < 0.05) inverse correlation with triglyceride concentrations in women receiving HT. CONCLUSIONS: The effect of HT on alternate days on ucOC concentration was weaker than the effect of HT daily. In addition, ucOC concentration after 12 months of HT daily might be decreased due to the conversion of ucOC to carboxylated OC by the effect of vitamin K through increased triglyceride levels induced by oral CEE.

Biomarkers↗