Biomedical subjects

S Yamano

Publications and source records attributed to S Yamano.

133 records · Page 8Linked to original sources

PubMedDate not supplied

The scheduled ovarian hyperstimulation method makes it easy to perform ICSI with fresh testicular sperm (ICSI/TESE).

The authors evaluated whether scheduled ovarian stimulation makes it easy to perform ICSI with fresh testicular sperm. Scheduled ovarian hyperstimulation was applied for testicular sperm extraction and ICSI with fresh testicular spermatozoa. Fifteen cycles in 10 couples were included in the present study; all couples were azoospermic, 5 were obstructive, and the remaining 5 were nonobstructive. No cycles were canceled, and all oocyte retrievals were performed on the scheduled day. Testicular sperm were obtained in 14 treatment cycles (93%). The mean numbers of retrieved and injected oocytes were 9.4 and 6.4, respectively. The fertilization and cleavage rates were 47 and 91%, respectively. Embryo transfers were performed in 12 cycles except 2 cycles that had no embryos. The number of transferred embryos was 2.3. Two clinical pregnancies were obtained. This scheduled ovarian hyperstimulation was applicable for ICSI with fresh testicular sperm.

Adult↗

PubMedDate not supplied

Postmenopausal changes in production of type 1 and type 2 cytokines and the effects of hormone replacement therapy.

OBJECTIVE: An appropriate defense against infective agents or malignant cells is attributed to the exquisitely balanced T helper 1 type (cellular) and T helper 2 type (humoral) immune reactions. We investigated the effect of hormone replacement therapy (HRT) on postmenopausal changes in the production of interferon (IFN)-gamma and interleukin (IL)-10, a type 1 and a type 2 cytokine, respectively. DESIGN: Both cytokines were measured by ELISA in the supernatant of lipopolysaccharide-stimulated whole blood cells from 72 untreated and 44 HRT-treated women. Thirteen women were examined before and during HRT. RESULTS: The production of IFN-gamma in women in their 40s and in postmenopausal women was significantly higher compared with that of younger women. However, IFN-gamma fell to the lowest level in the late postmenopausal stage, whereas the production of IL-10 increased gradually with age and in parallel with the postmenopausal period. Thus, in women in the mid-and late postmenopausal period, excessive production of type 2 cytokine (IL-10) compared with type 1 cytokine (IFN-gamma) occurred. The IFN-gamma levels of women on HRT were significantly lower than those of untreated women in the early and mid-postmenopausal stages, and IL-10 levels of women on HRT were significantly lower than those of untreated women in the mid-and late postmenopausal stages. HRT induced a significant decrease in the production of IL-10 and tended to lower the level of IFN-gamma. CONCLUSIONS: Production of IL-10 is augmented in postmenopausal women. HRT probably prevents postmenopausal women from an aberration of the immune system by improving the balance of type 1 and type 2 immune reactions.

Adult↗

PubMedDate not supplied

Increase of intracellular free [Ca2+] in single human motile spermatozoa treated with human follicular fluid.

The intracellular free [Ca2+] concentration ([Ca2+]i) in individual human sperm was measured using a fluorescent Ca2+ indicator. In 18 of 23 motile sperm (78.3%), [Ca2+]i increased significantly and promptly after addition of 20% human follicular fluid (hFF), but in the others it did not increase. The mean resting [Ca2+]i level of sperm in which [Ca2+]i increased after addition of 20% hFF (the influx group) was significantly lower than those in which it did not increase (112.8 +/- 40.1 nM vs. 156.9 +/- 13.5 nM, p < .05). After addition of 20% hFF, the mean [Ca2+]i in the influx group reached a peak value of 210.7 +/- 24.7 nM within 30 s and then decreased slowly; the mean [Ca2+]i values 1, 5, 10, and 15 min after addition of 20% hFF were 179.3 +/- 31.4, 174.3 +/- 30.2, 172.5 +/- 27.8, and 175.1 +/- 27.2 nM, and all values were significantly higher than the resting level (p < .01). The frequency distribution of [Ca2+]i after addition of 20% hFF was shifted toward higher concentrations (p < .01). However, the addition of 20% hFF did not increase the percentage of live acrosome reaction (before 3.8 +/- 0.9% vs. after 2.9 +/- 0.5%, respectively). Thus, hFF increased [Ca2+]i in about 80% of the motile sperm. Relatively high [Ca2+]i levels persisted for at least 10-15 min after its addition. However, hFF did not trigger a rapid response in acrosome reaction.

Acrosome↗

PubMedDate not supplied

Exposure of human sperm to low-calcium medium enhances fertilizing ability.

This investigation was conducted to evaluate whether exposure of human sperm to low calcium enhances the fertilizing ability. When sperm from normal semen samples were preincubated in low-calcium mBWW medium for 1 h, the percentages of live acrosome-reacted sperm after 4 and 6 h of culture were significantly higher than control (5.0 +/- 0.5 vs. 3.2 +/- 0.3% and 6.0 +/- 0.5 vs. 4.2 +/- 0.3%, p < .05). The penetration rate (%P) and fertility index (FI) in zona-free hamster egg sperm penetration assay significantly increased, compared to control (%P: 66.4 +/- 9.0 vs. 42.7 +/- 8.1%; FI: 1.69 +/- 0.19 vs. 1.34 +/- 0.11; p < .01). When low-calcium treatment was used for human in vitro fertilization and embryo transfer (IVF-ET) for male infertility, the fertilization and pregnancy rates were significantly higher than those in control. The results indicate that preincubation of human sperm in low-calcium medium enhances their fertilizing ability. This method is a simple and useful for preparing sperm from subfertile men for human IVF-ET.

Acrosome↗

PubMedDate not supplied

Characteristics of calcium ion influx induced by human follicular fluid in individual human sperm.

The mechanism of Ca2+ influx into human spermatozoa was investigated. Human follicular fluid (hFF), which contains progesterone, stimulated an increase in the concentration of intracellular free Ca2+ ([Ca2+]i) as measured by fluorescence spectroscopy using Fura-2/AM. The technique allowed the measurement of [Ca2+]i in individual, motile spermatozoa, by improvement of the previous methods. The role of Ca2+ channels was investigated using selective blocking agents. Neither blockade of L-type channels with verapamil or lanthanum (La3+) nor blockade of N-type channels with omega-conotoxin affected the hFF-stimulated increase in [Ca2+]i. Blockade of T-type channels with either nickel (Ni2+) or amiloride significantly reduced the hFF-stimulated increase in [Ca2+]i and amiloride significantly decreased baseline [Ca2+]i. Incubation of sperm in Na(+)-free medium did not affect [Ca2+]i, indicating that Na+/Ca2+ exchange has no major role in Ca2+ influx. The results suggest that calcium influx induced by hFF occurs via T-type voltage-independent Ca2+ channels. The method described allows accurate measurement of [Ca2+]i in individual, motile human spermatozoa.

Amiloride↗

PubMedDate not supplied

Semen analysis and antisperm antibody.

Evaluation of the fertilizing potential of sperm is an important procedure in in vitro fertilization and embryo transfer (IVF-ET) clinic, in order to avoid performing invalid conventional IVF-ET or unnecessary intracytoplasmic sperm injection (ICSI). However, none of the standard semen parameters are reliable indices in predicting IVF outcome. The test examining sperm-zona interaction is the best present method, though the short supply of the human zona component should be solved. IVF-ET treatment is useful for pregnancy in women having sperm immobilizing antibodies because it avoids exposing sperms to antibodies that block fertilization. ICSI should be used in immunologically infertile men diagnosed by specific method to demonstrate the in vivo exposure of sperms to antisperm autoantibodies that block fertilization.

Antibodies↗

PubMedDate not supplied

Stimulation mechanism of guinea pig liver-mediated reduction of naloxone by morphine.

The mechanism of the stimulatory effect of morphine on the reduction of naloxone has been elucidated using guinea pig liver naloxone reductase that is identical with morphine 6-dehydrogenase. The reaction products were quantitated by means of HPLC. When naloxone was incubated with the enzyme in the presence of NAD(P)H at pH 7.4 or pH optima, the production of 6 alpha-naloxol increased according to the added amount of morphine. The stimulation was predominant with NADH at pH 7.4. Under these conditions, the production of morphinone also increased in proportion to the amount of morphine. The enzymatic reduction of naloxone proceeded even if NAD(P)H was replaced by NAD(P)+ and morphine. At a fairly low concentration of NADH (0.01 mM), the enzyme produced 6 alpha-naloxol (0.3 mM), exceeding the stoichiometric amount in the presence of 16 mM morphine. Although the Vmax values for naloxone was increased by the addition of morphine, the Km values for naloxone remained unaltered. Besides other substrates for guinea pig liver morphine 6-dehydrogenase such as codeine, normorphine and ethylmorphine also enhanced the reduction of naloxone. From these results we concluded that the stimulation of guinea pig liver-mediated reduction of naloxone by morphine is caused by the acceleration of the redox of pyridine nucleotides conducted by the enzyme. These phenomena were further supported by the experiments with the liver cytosol. In addition, we confirmed that, in the guinea pig, the biliary excretion of the metabolites, naloxol and naloxol-3-glucuronide, increased after sc injection of naloxone with morphine.

Alcohol Oxidoreductases↗