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Y Sakuma

Publications and source records attributed to Y Sakuma.

At least 109 records · Page 6Linked to original sources
PubMed1994

Estrogen-induced changes in the neural impulse flow from the female rat preoptic region.

Electrical stimulation of the medial preoptic area (MPO) interrupted the lordosis reflex, the major receptive component of female rat sexual behavior, without interfering with proceptivity. In contrast, axon-sparing MPO lesions with a neurotoxin enhanced lordosis and diminished solicitatory behavior. The MPO effect on the lordosis reflex was mediated by its projection to the ventral tegmental area (VTA) because electrical stimulation of the VTA had a similar effect. In the urethane-anesthetized rats, electrical stimulation of the VTA elicited antidromic action potentials in neurons in the core of the MPO. In the ovariectomized females and neonatally castrated males, but not in the androgenized females, estrogen increased thresholds and prolonged refractory periods for the antidromic activation. Thus the neural effect of estrogen was limited to those animals that showed lordosis in the presence of this steroid. Estrogen also inhibited neurons in the dorsal part of the MPO, which project to the midbrain locomotor region (MLR), but had an opposite excitatory effect on MLR-projection neurons in the medial part of the lateral preoptic area (mLPO). Estrogen may therefore enhance lordosis by reducing neural impulse flow from the MPO to the VTA. A reduced MPO output to the MLR, combined with an augmentation of the mLPO effect, may culminate in increased locomotion in the female rats in estrus, because the MPO suppresses locomotor activity whereas the mLPO facilitates it.

Animals↗
PubMed1994

Estrogen reduces the excitability of the female rat medial amygdala afferents from the medial preoptic area but not those from the lateral septum.

Electrical stimulation of the medial amygdala (AMY) elicited antidromic action potentials in neurons in the preoptic area (POA) and the lateral septum (LS) of 36 urethane-anesthetized ovariectomized female rats, which were either treated with estrogen o not treated. The extracellular potentials from the two sites showed similar characteristics, with the exception of the sensitivity to estrogen: they had latencies between 3 and 35 ms. Thresholds were as low as 100 microA. The mean relative refractory period was 2.2 ms. The peak-to-peak amplitudes of the positive-negative biphasic potential ranged from 1.0 mV to 12.0 mV. Estrogen had site-specific effects on parameters of antidromic activation in the POA. Estrogen-treated rats had a significantly higher threshold (937 vs 664 microA) and a longer refractory period (2.5 vs 2.1 ms) than the ovariectomized rats (P < 0.05 for each). The effects were absent in the LS. Selective cutting of the stria terminalis diminished the AMY-induced antidromic responses in the POA and LS. Electrical stimulation of the stria blocked the AMY-induced antidromic potentials by collision. Thus, estrogen-sensitive POA efferents as well as non-estrogen-sensitive LS efferents project to the AMY via the stria terminalis. Reductions in axonal excitability would inhibit neural conduction and transmission. Estrogen may therefore reduce the AMY inputs from the POA, without affecting those from the LS. Such alterations in the neural impulse flow may underlie estrogen-dependent neuroendocrine or behavioral regulation.

Amygdala↗
PubMed1994

Effects of anti-progesterone compound RU486 on ovulation in immature mice treated with PMSG/hCG.

The effects of RU486, a competitive antagonist of progesterone, on ovulation were studied in PMSG/hCG-treated immature mice. PMSG/hCG was administered to 3-week-old female mice to induce ovulation. A dose of 0.5 mg of RU486 was administered 3 h before hCG injection, simultaneously with hCG injection, or 3, 4.5, 6, 7.5 or 9 h after hCG administration. The lowest number of ovulated eggs was observed in the group given RU486 6 h after hCG injection. Although the mean number of ovulated eggs was only 4.4 in this group, it was increased to 25.7 by supplementary administration of 2.0 mg of progesterone. It was demonstrated that RU486 had inhibitory effects on ovulation, and the inhibition could be prevented by supplementary administration of progesterone.

Animals↗
PubMed1994

Dihydrotestosterone-sensitive neurons in the male rat ventromedial hypothalamus.

Electrical stimulation of the midbrain central gray caused antidromic activation in 273 neurons in and around the hypothalamic ventromedial nucleus in 40 urethan-anesthetized male rats. The latency (range: 2-39 ms) and threshold (100-1,600 microA) of the responses were compared among intact males and orchidectomized males, which received either no treatment, daily injections of testosterone propionate or dihydrotestosterone, or a combined estradiol benzoate and progesterone injection. Recordings were from comparable neuronal pools, because probability distribution for the latency as well as histological localization of each response were not different among groups. Orchidectomy decreased the mean threshold, and either treatment reversed the effect. Dihydrotestosterone increased the mean threshold by reducing the number of cells with thresholds below 600 microA, to a level as in intact males. Estrogen reduced the number of cells responding at 300-900 microA, but at lower thresholds, fell short of replicating the distribution in intact males. Testosterone reinstated the distribution as in intact males. It was concluded that different subgroups of ventromedial hypothalamic neurons with specific sensitivity to metabolites of testosterone project to the central gray.

Action Potentials↗
PubMed1994

Computer prediction of general PCR products based on dynamical solution structures of DNA.

A computer program which can predict general PCR products was developed and experimentally verified to be useful. This means that the approximation of solution structures of DNA based solely on Watson-Crick base pairing is effective. Intramolecular higher structures were shown to be responsible for the discrepancies between the predictions and the experimental results. This study provides a theoretical background to arbitrarily primed (or random) PCR. Other basic issues relating to general PCR are also discussed.

Base Sequence↗
PubMed1994

Survival of genetically-engineered and wild-type strains of the yeast Saccharomyces cerevisiae under simulated environmental conditions: a contribution on risk assessment.

A genetically-engineered strain of Saccharomyces cerevisiae employed for the industrial production of the human coagulation Factor XIIIa (rhFXIIIa) was used for a survival study under simulated environmental conditions. The homologous strain devoid of the recombinant plasmid and the homologous strain bearing the 2 microns-based vector plasmid without the rhFXIIIa-encoding DNA insert were compared. The strains were introduced into natural soil/water suspension, into soil/medium suspension and into waste water. After intervals, samples of cell suspensions were taken and viable cell numbers were determined by plating on antibiotic-containing medium. In addition, a non-radioactive technique involving enhanced chemiluminescence was employed to detect plasmid-bearing yeast cells. The rhFXIIIa expression plasmid showed a high stability during the simulated environmental condition. No differences in survival rates, however, could be detected for the plasmid-bearing and plasmid-less strains under the three conditions tested, suggesting that the presence of plasmid does not confer selective advantages on the survival of the yeast cells. It is concluded that, even after accidental release of the engineered yeast cells into the environment, elimination rates would be comparable to those for non-recombinant yeast strains.

Environmental Microbiology↗
PubMed1994

Simplification of superovulation induction by using polyvinylpyrrolidone as a solvent for FSH in rabbits.

With a view to simplify the method of inducing superovulation in rabbits, polyvinylpyrrolidone (PVP) was used as a solvent for follicle-stimulating hormone (FSH). As a result, it became clear that more than the equivalent number of ovulation points and fertilized ova that are obtainable by the conventional six injections of FSH were able to be obtained by only a single injection of FSH-PVP preparation. Inflammation or swelling of the tissue was not observed in the injection site or its vicinity. The results seem to enable simplification of superovulation induction by using PVP as a vehicle for FSH in rabbits. This finding could reduce injection distress to the animals and labor of the operator.

Animals↗
PubMed1994

Specular microscopy of corneal endothelial cells in cynomolgus monkeys.

The corneal endothelia of 15 male and 16 female cynomolgus monkeys (estimated age: 2 years and more) were examined with a contact-type specular microscope under general anesthesia. The specular microscopy showed uniform-sized, hexagonal endothelia arranged regularly on the innermost layer of the cornea. Concerning the cell density (cells/mm2), no statistically significant difference was observed between the left and right eyes or between sexes. However, the cell density decreased in monkeys over 7 years old.

Aging↗
PubMed1994

[Release of chemical mediators in the conjunctival lavage fluids after eye provocation with allergen or compound 48/80].

Allergen extract was used to perform conjunctival provocation test on patients with Japanese cedar pollen conjunctivitis during the off-season, and histamine, tryptase and immunoreactive-leukotriene C4 (i-LTC4), which mainly consisted of LTE4, were measured in the lavage fluids. The results obtained in this study were as following. 1) After instillation of the allergen extract (1:20, w/v, 0.01 ml), histamine reached a maximal level of 4.63 +/- 1.67 ng/ml (mean +/- SE, n = 11) at 5 min. Tryptase appeared more slowly and the peak levels were reached at 5 min (116.6 +/- 49.6 ng/ml) or 10 min (119.4 +/- 63.8 ng/ml). In another set of the experiments, histamine peaked at 5 min (3.84 +/- 1.08 ng/ml, n = 7), and i-LTC4 reached peaks at 5 min (320 +/- 44.4 pg/ml) or 10 min (367 +/- 64.8 pg/ml). The amounts of these mediators decreased to base-line levels by 30 min. 2) The amounts of histamine retrieved from the lavage fluid were significantly correlated with those of tryptase (r = 0.819, p < 0.01, n = 11) and the weight ratio of tryptase to histamine was 41.2 +/- 10.0. These observations suggest that histamine was released from mast cells. 3) A significant correlation between the levels of histamine and i-LTC4 recovered from the lavage fluids was also observed (r = 0.736, p < 0.05, n = 7). 4) Compound 48/80 was instilled in the right eye (7.5 mg/ml, 0.01 ml) and the left eye was given allergen solution.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗
PubMed1994

[Characterization of anti human uterine endometrial cancer antibody (MSN-1) and its usefulness in clinical application].

We have produced a monoclonal antibody (MSN-1), by using our endometrial cancer-cultured cell line (SNG-II) as an immunogen. MSN-1 belongs to the IgM immunoglobulin class and mainly recognized the Lewis carbohydrate moiety. It seldom, reacted immunohistochemically with normal endometrium but with about 90% of endometrial cancer cases. So, we evaluated the effectiveness of its use in clinical application. We studied the relationship between the stage of cancer and reactivity to MSN-1, and that between the reactivity of moderately differentiated endometrial cancer to MSN-1 and a 5-year survival rate. Endometrial cancer with a poor prognosis tended to react poorly to MSN-1, suggesting the possibility that the reactivity to MSN-1 is useful as a new prognostic factor. A study of endometrial hyperplasia revealed that the reactivity to MSN-1 was high in the high risk group (individuals diagnosed as endometrial cancer later). This suggested that the analysis of the expression of the antigen recognized by MSN-1 is useful in selecting the high risk group out of patients with endometrial hyperplasia. Furthermore, we indicated that abnormal expression of the antigen recognized by MSN-1 associated with neoplasia of endometrial cells is useful in developing a new diagnostic method for example our endometrial cell enzyme immunoassay (EmC-EIA) and will be helpful in developing diagnostic approaches, such as missile therapy with a complex of MSN-1 and adriamycin for endometrial cancer.

Antibodies, Monoclonal↗
PubMed1993

Developmental effect of testosterone on estrogen sensitivity of the rat preoptic neurons with axons to the ventral tegmental area.

The neonatal effect of testosterone on neuronal sensitivity to estrogen was examined in the medial preoptic area of the rat when adult. Electrical stimulation of the ventral tegmental area induced antidromic action potentials in 683 neurons in 106 urethane-anesthetized animals which consisted of 38 males castrated on the day of birth (day 1), 30 females androgenized by testosterone injection on day 5, and 38 normal females. All females were used after ovariectomy when adult. Histological localization of the antidromically activated neurons was similar in all the animal groups. The latency jump in 40% of the potentials indicated that activated preoptic axons terminate in the stimulation site. The latency for activation was in the range 1.6-43.7 ms and the threshold was as low as 60 microA. The absolute refractory period did not exceed 1700 microseconds. Estrogen increased the threshold among 278 cells in the normal females and 181 cells in the neonatally castrated males. Preoptic neurons in the androgenized females (n = 224) differ from those in others in that their threshold, regardless of estrogen treatment, was at the ceiling values seen in the other groups in the presence of estrogen. Estrogen also prolonged the absolute refractory period in the females but not in the androgenized females. The reduced excitability and the lack of estrogen sensitivity may be responsible for the insensitivity of the androgenized females to feminine actions of estrogen, that may presumably underlie a sex difference in certain behavioral functions.

Action Potentials↗
PubMed1993

Suppression of the lordosis reflex of female rats by efferents of the medial preoptic area.

In freely moving, estrogen- and progesterone-treated ovariectomized female rats, electrical stimulation of the medial preoptic area, which had been isolated dorsally from the septum by a horizontal knife cut (roof cut), caused immediate interruption of the lordosis reflex, a principal component of female reproductive behavior in this species. Neither the knife cut nor the stimulation affected their proceptive interactions with the males. Lordosis was interrupted in a graded manner in response to increased stimulus intensity, with a threshold at 30 microA. The optimal frequency was at 50-100 Hz. Lordosis was reinstated promptly by the termination of current application. The rapid time course distinguished the stimulation effect in the rats with the roof cut from that in the intact control animals, which was slow in its onset and recovery. In the sham-operated animals, an adjunct bilateral cut of the stria terminalis was sufficient to restore the rapid response as in the roof-cut animals. The roof-cut animals were sensitive to lower doses of estrogen than those without the knife cut; therefore, the preoptic area appears to be a separate entity from the septum in the inhibitory control of lordosis. The elimination of facilitatory neural components for this reflex, which enter the preoptic area dorsally via the stria terminalis, might be responsible for the prompt and exaggerated stimulation effect in the roof-cut animals.

Afferent Pathways↗
PubMed1993

Estrogen-sensitive neurons in the female rat ventral tegmental area: a dual route for the hormone action.

1. Electrical stimulation of the ventral part of the midbrain central gray (CG) elicited antidromic action potentials in 136 neurons in the ventral tegmental area (VTA) of 23 urethan-anesthetized ovariectomized female rats. 2. Antidromic action potentials were positive-negative biphasic and completed mostly within 2.4 ms. Many had a notch in their initial positive deflection, at which antidromic potentials often failed to propagate into the neuronal soma. 3. The latency for antidromic activation ranged 1.0-10.5 ms, and the threshold was 100-1,700 microA. The relative refractory period was 0.8-2.8 ms. In 23 neurons (17%) gradual changes in stimulus intensity caused latency jumps, suggesting that their axons terminate or spread into branches in stimulation sites. 4. The parameters for antidromic activation were compared among 12 animals with a subcutaneous Silastic capsule of estrogen and 11 others with a blank capsule. Estrogen raised the mean threshold from 675 +/- 40 (SE) microA (n = 69) to 908 +/- 40 microA (n = 67). At the same time, estrogen significantly decreased the probability of the antidromic propagation from 63 to 41%. No changes were detected in the latency or the refractory period. 5. The probability distribution of the threshold was different in ovariectomized animals from that in estrogen-treated animals. Estrogen increased the number of cells with thresholds in the 1,300- to 1,500-microA range. 6. The probability of antidromic propagation was stable in each neuron to stimuli repeated at 1.0 Hz. Electrical stimulation of the preoptic area (POA) with a 30-s train of 50-microA pulses at 100 Hz increased the probability of antidromic propagation into the soma.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1993

Inhibition of IgE-mediated leukotriene generation and bronchoconstriction in primates with a new 5-lipoxygenase inhibitor, E6080.

The inhibitory effects of a novel compound, 6-hydroxy-2-(4-sulfamoylbenzylamino)-4,5,7-trimethylbenzothiazo le hydrochloride (E6080) on IgE-mediated reactions in vitro and in vivo were determined in rhesus monkeys. E6080 inhibited both antigen- and anti-human IgE-induced leukotriene C4 generations from lung fragments at similar concentrations: the IC50s of E6080 were 1.11 and 0.96 microM, respectively. AA861 also inhibited both leukotriene C4 generations with IC50s of 0.79 and 0.76 microM, respectively. All 9 monkeys demonstrating positive cutaneous reactivity against Ascaris antigen at < 10(-7) g protein/0.1 ml showed reproducible bronchoconstriction upon aerosolized antigen challenge, but 5 monkeys demonstrating weak or no reactivity to the antigen at levels > 10(-5) g protein/0.1 ml showed no significant bronchoconstriction. The high responder monkeys showed a marked increase in lung resistance (RL 335.3 +/- 85.3%, n = 11) and a decrease in dynamic lung compliance (67.7 +/- 4.2%, n = 11) after antigen challenge following pretreatment with diphenhydramine. These pulmonary changes lasted for more than 30 min. E6080 at oral doses of 3 and 10 mg/kg showed dose-dependent inhibition of both pulmonary changes. Ten milligrams per kilogram of E6080, administered 1.5 h prior to antigen challenge, significantly inhibited the changes in both parameters, while 3 mg/kg showed significant inhibition of only the RL change. These results demonstrate that E6080 inhibited immunologically stimulated leukotriene production in the lung, resulting in inhibition of the antigen-induced airway response in primates.

Animals↗
PubMed1993

Pharmacological properties of blood pressure and heart rate control in suncus.

Blood pressure and heart rate and responses to various physiological substances in suncus were characterized and compared with those in mice. The blood pressures of the two species were similar, but the heart rate of suncus (about 400 beat/min) was significantly lower than that of mice. Norepinephrine increased the blood pressure but decreased the heart rate in suncus. The latter was blocked by cervical vagotomy. Sensitivities to acetylcholine and isoproterenol were lower in suncus. These results suggest that regulation of blood pressure and heart rate in suncus is very unique and different from the well-defined system of the rodents.

Acetylcholine↗
PubMed1993

[The partial resection of lung with MULTIFIRE ENDO GIA 30 under the thoracoscopy].

MULTIFIRE ENDO GIA 30 was a newly auto suture developed by US surgical c.o., A 27-year-old man was admitted for right spontaneous pneumothorax in our hospital. We performed the partial resection of lung with this new auto suture under the thoracoscopy. Condition of patient after operation was very good, and he could discharge in short hospitalization. We concluded that this new auto suture was entirely reversible and safety.

Adult↗
PubMed1992

Relation between the number of sperms to be deposited and pregnancy rate in tubal insemination in rabbits.

Pregnancy rate of tubal insemination with semen diluted to concentrations of x10(0) to x10(7) was studied in rabbits. The animals were laparotomized under general anesthesia, and 0.05 ml of diluted semen was injected with a glass capillary from the tubal fimbria into the oviduct. The semen was obtained from mature male rabbits by means of an artificial vagina and diluted to concentrations between x10(0) and x10(7). One hour after the insemination, ovulation was induced by administration of hCG. Six experimental groups were set up according to the semen concentrations. In the x10(0), x10(2), x10(4), and x10(7) groups, newborn rabbits were obtained. The best pregnancy rate was obtained with the x10(2) groups, in which 10(5) level of sperms were deposited. The newborn rabbits were normal not only morphologically, functionally, but also in chromosomal examination. The results suggested that tubal insemination with a small number of sperms could be applied in sterility due to oligospermia in human.

Animals↗