Biomedical subjects

A Miyake

Publications and source records attributed to A Miyake.

At least 181 records · Page 10Linked to original sources

PubMed1992

Atrial and brain natriuretic peptides enhance dopamine accumulation in cultured rat hypothalamic cells including dopaminergic neurons.

Dopamine accumulation in hypothalamic cells by atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) was analyzed using newborn rat hypothalamic cells in culture. Both ANP and BNP caused a dose-dependent increase in [3H]-dopamine accumulation in the cells. ANP increased [3H]-dopamine accumulation significantly within 20 min. The effects of ANP and BNP on dopamine accumulation paralleled an increase in intracellular cGMP concentration. (Bu)2-cGMP and sodium nitroprusside, a stimulator of the soluble form of guanylate cyclase, also enhanced [3H]-dopamine accumulation. ANP had no effect on efflux of [3H] radioactivity after [3H]-dopamine uptake. These results suggest that a change in cGMP is one of the intermediate steps in dopamine accumulation in hypothalamic cells by ANP and BNP.

Animals↗

PubMed1992

Hysteroscopic assessment of midsecretory-phase endometrium, with special reference to the luteal-phase defect.

To investigate the functional aspects of secretory-phase endometrium, hysteroscopy was performed in 61 patients for in vitro fertilization-embryo transfer (IVF-ET), and 50 women for infertility evaluation. All women had normal ovulatory cycles. The hysteroscopic assessment of secretory-phase endometrium was made by characterizing the glandular openings (GO) and vasculature. The assessments were classified as 'good': characterized by ring-type GO and well-developed vessels; and 'poor': characterized by dot and/or punctate-type GO and fine vasculature. In the 30 patients classified 'good' prior to the IVF cycle, there was a higher pregnancy rate (40%) than in 'poor' ones (13%). Thirty of 50 infertile women were classified 'good', and their average age was lower than that of the remaining 20 in the 'poor' group. Preovulatory estradiol was significantly higher in the 'good' than in the 'poor' group. From an analysis of 20 patients with a 'poor' assessment, it was demonstrated that the maturation of secretory-phase endometrium was affected by a failure of folliculogenesis, progesterone secretion, endometrial growth and menstrual shedding.

Adult↗

PubMed1992

Immunohistochemical evidence that rat FSH cells contain beta II-subspecies of protein kinase C.

Immunocytochemical double-staining analysis revealed that in the rat anterior pituitary 86% of cells containing the beta II-subspecies of protein kinase C also contained follicle stimulating hormone (FSH), and that 22% of these FSH cells expressed the beta II-subspecies. These findings suggest a close relationship between the beta II-subspecies of protein kinase C and FSH regulation.

Animals↗

PubMed1992

No inhibitory effects of gestrinone and medroxyprogesterone acetate on the estrogen production by ovaries of hypophysectomized rats stimulated by gonadotropins.

The in vivo effects of gestrinone (R2323) and medroxyprogesterone acetate (MPA) on the estrogen production by rat ovaries were investigated. Hypophysectomized immature female rats treated with 2.5 or 5 IU of pregnant mare serum gonadotropin (PMS) were daily given vehicle only, gestrinone (0.5 mg/kg body weight) or MPA (10 mg/kg body weight), and the activities of 3 beta-hydroxysteroid dehydrogenase, 17 alpha-hydroxylase, 17, 20-lyase, 17 beta-hydroxysteroid dehydrogenase and aromatase in ovaries of these rats were measured. Gestrinone suppressed the 3 beta-hydroxysteroid dehydrogenase activity and increased activities of 17 alpha-hydroxylase, 17, 20-lyase and aromatase in ovaries stimulated by 5 IU of PMS, while MPA suppressed activities of 17 alpha-hydroxylase and aromatase in these ovaries. On the other hand, the aromatase activity in ovaries stimulated by 2.5 IU of PMS was suppressed by gestrinone and increased by MPA, and neither gestrinone nor MPA affected the production of aromatizable androgens from progesterone by these ovaries. Thus, gestrinone and MPA administrated in vivo showed divergent influences on steroidogenic enzyme activities in ovaries, but they did not affect the serum concentration of estradiol-17 beta. The present results suggest that neither gestrinone nor MPA reduced estrogen production by the rat ovary under the gonadotropin stimulation although they influenced some process of its steroidogenesis.

17-Hydroxysteroid Dehydrogenases↗

PubMed1992

Intraventricular administration of thyrotrophin-releasing hormone (TRH) suppresses prolactin secretion and synthesis: a possible involvement of dopamine release by TRH from rat hypothalamus.

The administration of thyrotrophin-releasing hormone (TRH) causes a variety of dopamine-related biological events. To understand the specific role of TRH on rat hypothalamic dopamine neurones, we examined the in-vivo effects of intraventricular (i.c.v.) infusion of TRH on the release and synthesis of prolactin in the rat pituitary gland and on the changes in binding of [3H]MeTRH and dopamine turnover rates in rat hypothalamus. We have also examined the in-vitro effects of TRH on the release of [3H]dopamine from dispersed tuberoinfundibular dopamine neurones. Female rats were treated with i.c.v. infusions of 1 mumol TRH/1 daily for 1, 3 and 7 days using Alzet osmotic pumps. Following 7 days of treatment the serum prolactin concentrations were significantly decreased. A reduction in hypothalamic TRH-binding sites (Bmax) was also apparent but the dissociation constant (Kd) was unaffected. Northern blot analysis of total RNA isolated from the pituitary glands of control animals using 32P-labelled prolactin cDNA as a probe indicated the presence of three species of prolactin gene transcripts of approximately 3.7, 2.0 and 1.0 kb in size, and these were decreased by TRH treatment. We examined the turnover rate of dopamine in the rat hypothalamus when TRH was administered i.c.v. for 7 days. There was a significant increase in 3,4-dihydroxyphenylacetic acid/dopamine ratio with TRH treatment. Moreover, exposure to TRH stimulated [3H]dopamine release from rat tuberoinfundibular neurones in a time- and dose-dependent manner. Dopamine receptor antagonists such as SCH23390 and (-)sulpiride, and other neuropeptides such as vasoactive intestinal peptide and oxytocin did not affect TRH-stimulated [3H]dopamine release.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dihydroxyphenylacetic Acid↗

PubMed1992

Studies on condensed-heterocyclic azolium cephalosporins. III. Synthesis and antibacterial activity of 7 beta-[2-(2-amino-5-substituted-thiazol-4-yl)-2 (Z)-alkoxyiminoacetamido]-3-(condensed-heterocyclic azolium)methyl-3-cephem-4- carboxylates.

As a part of our research on the synthesis of cephalosporins bearing condensed-heterocyclic azolium groups at the 3 position in the cephalosporin nucleus, we describe herein the synthesis of 7 beta-[2-(2-amino-5-halogeno-, methylthio-, methylsulfinyl-, methylsulfonyl- and sulfothiazol-4-yl)-2(Z)-alkoxyiminoacetamido] cephalosporins and their antibacterial activity. Among the compounds prepared, 7 beta-[2-(2-amino-5-chlorothiazol-4-yl)-2(Z)- methoxyiminoacetamido]-3-(imidazo[1,5-a]-pyridinium-1-yl)methyl-3-cephem -4-carboxylate (14) showed good antibacterial activity against both Staphylococcus aureus including methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, whereas the antibacterial activity against other Gram-negative bacteria was a slightly lower than that of 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-methoxyiminoacetamido]-3-(im ida zo [1,2-a]pyridinium (I-1) and imidazo[1,5-a]pyridinium (I-4)-1-yl)methyl-3-cephem-4-carboxylates.

Anti-Bacterial Agents↗

PubMed1992

Studies on condensed-heterocyclic azolium cephalosporins. IV. Synthesis and antibacterial activity of 7 beta-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2(Z)- alkoxyiminoacetamido]-3-(condensed-heterocyclic azolium)methyl cephalosporins including SCE-2787.

The synthesis and in vitro antibacterial activity of 7 beta-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2(Z)-alkoxyiminoacetami do] cephalosporins bearing various condensed-heterocyclic azolium groups at the 3 position in the cephalosporin nucleus are described. The thiadiazolyl cephalosporins showed good antibacterial activity against both Gram-positive and Gram-negative bacteria and the MICs of the thiadiazolyl cephalosporins against Pseudomonas aeruginosa was more potent than that of the corresponding 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-alkoxyiminoacetamido]-3- (condensed-heterocyclic azolium)methyl cephalosporins. Also, the thiadiazolyl cephalosporins bearing (imidazo[1,2-b]-pyridazinium-1-yl)methyl groups at the 3 position showed antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA). Among the cephalosporins tested, 7 beta-[2-(5- amino-1,2,4-thiadiazol-3-yl)-2(Z)-methoxyiminoacetamido]-3-(imidaz o[1,2- b]pyridazinium-1-yl)methyl-3- cephem-4-carboxylate (4, SCE-2787) which exhibited the most potent antibacterial activity and the broadest antibacterial spectrum was selected as a parenteral cephalosporin candidate for further biological evaluation.

Cephalosporins↗

PubMed1992

Studies on condensed-heterocyclic azolium cephalosporins. V. Synthesis and antibacterial activity of 3-(condensed-triazolo-pyridinium, -pyrimidinium, and -pyridazinium)-methyl cephalosporins.

As a part of our studies on cephalosporins bearing condensed-heterocyclic azolium methyl groups at the 3 position in the cephalosporin nucleus, we describe here the synthesis and antibacterial activity of 7 beta-[2-(2-aminothiazol-4-yl)2(Z)-methoxyiminoacetamido] cephalosporins (1-16, 7 beta-[2-(2-amino-5-chlorothiazol-4-yl)-2(Z)- methoxyiminoacetamido] cephalosporins (17,18) and 7 beta-[2-(5-amino- 1,2,4-thiadiazol-3-yl)-2(Z)-methoxyiminoacetamido) cephalosporins (19-23) containing a variety of condensed-heterocyclic triazolium methyl groups at the 3 position in the cephalosporin nucleus. These cephalosporins exhibited potent antibacterial activity, and it appears that condensed-heterocyclic triazolium as well as condensed-heterocyclic imidazolium rings are effective moieties for improving antibacterial activity and the spectrum of activity. Among the cephalosporins tested, 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-methoxyiminoacetamido]-3-(5- methyl[1,2,3]triazolo-[1,5-alpha]pyridinium-1-yl)methyl-3-cephem-4- carboxylate (9) and 7 beta-[2-(2-aminothiazol-4-yl)-2(Z)-methoxyiminoacetamido]-3-(6- methoxy[1,2,4]triazolo[1,5-alpha]pyridinium-1-yl)methyl-3-cephem-4- carboxylate (11) showed good antibacterial activity.

Cephalosporins↗

PubMed1992

[Roles of calcium ion in reproductive physiology].

Physiological role and importance of calcium ion has been investigated based on the study of the mechanism of muscle contraction. Furthermore, calcium ion has been proved to have a wide variety of biological roles in hormonal secretion, cell proliferation and reproduction as well as in muscle contraction. In this lecture, I would like to show a method to measure intracellular calcium ion concentrations ([Ca2+]i) and to give a general information about the roles of calcium ion to induce various cell activities. Then I would like to talk about the changes in intracellular calcium concentration ([Ca2+]i) and their meaning in the field of reproductive physiology including uterine muscle contraction, pituitary LH secretion, and fertilization. 1) Uterine muscle contraction and calcium ion The function of calcium ion is most intensively investigated in muscle contraction. We show [Ca2+]i increase in cultured myometrial cells. This increase is inhibited by omission of extracellular calcium or addition of calcium channel blockers. These results support usefulness of Ca2+ channel blockers in treating threatened premature delivery. We also report the action of MgSO4 as an inhibitory agent of [Ca2+]i increase stimulated by oxytocin. 2) Pituitary gonadotropin secretion and calcium ion Pituitary LH secretion is regulated by gonadotropin releasing hormone (GnRH). GnRH induces rapid increases and then sustained releases of LH secretion. By the omission of extracellular calcium, or by addition of Ca2+ channel blockers, the sustained phase of LH secretion is abolished. GnRH also increase [Ca2+]i in a very similar manner to that of LH secretion. The [Ca2+]i increase is essential in LH secretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗

PubMed1992

The novel natural product YM-26567-1 [(+)-trans-4-(3-dodecanoyl-2,4,6- trihydroxyphenyl)-7-hydroxy-2-(4-hydroxyphenyl)chroman]: a competitive inhibitor of group II phospholipase A2.

(+)-trans-4-(3-dodecanoyl-2,4,6-trihydroxyphenyl)-7-hydroxy-2-(4- hydroxyphenyl)chroman (YM-26567-1), a novel natural product isolated from the fruit of Horsfieldia amygdaline, dose-dependently inhibited group II phospholipase A2 (PLA2) prepared from rabbit platelet with an IC50 value of 6.7 microM (4.6-9.6 microM, n = 4). In contrast to irreversible PLA2 inhibitors such as manoalide and p-bromophenacyl bromide, the PLA2 inhibition of YM-26567-1 was independent of preincubation time. Lineweaver-Burk analysis revealed that YM-26567-1 behaved as a competitive inhibitor of rabbit platelet PLA2 with a Ki value of 1.6 +/- 0.3 microM (n = 5). Although YM-26567-1 also competitively inhibited group I PLA2 derived from porcine pancreas, the Ki value was approximately 10-fold greater for porcine pancreas than for rabbit platelet PLA2. In vivo, topical application of YM-26567-1 to the mouse ear inhibited 12-O-tetradecanoylphorbol-13-acetate (1 micrograms/ear)-induced mouse ear edema in a dose-dependent manner with a 50% effective dose of 28 micrograms/ear (13-63 micrograms/ear, n = 10/dose), but did not improve arachidonic acid (4 mg/ear)-induced mouse ear edema at 1 mg/ear. These results suggest that YM-26567-1 is a competitive PLA2 inhibitor showing a higher affinity for group II than group I PLA2, and that it may act as a potent anti-inflammatory compound through its direct inhibition of PLA2.

Animals↗

PubMed1992

[Ultrastructural observation of eosinophils in bronchoalveolar lavage fluid in eosinophilic pneumonia].

To investigate the morphological changes of local eosinophils in the lungs, we observed the ultrastructure of eosinophils in bronchoalveolar lavage fluid (BALF) from patients with eosinophilic pneumonia. We also measured the BALF concentration of eosinophil cationic protein (ECP) as an index of the activation of eosinophils. The eosinophils in BALF from patients with eosinophilic pneumonia showed various ultrastructural changes compared to eosinophils in BALF of the control patient. Changes included degranulation or disintegration of specific granules, cytoplasmic vacuolation, increased lipid droplets and the appearance of Charcot-Leiden crystals. These changes of BALF eosinophils were more prominent than those of peripheral blood eosinophils. ECP concentration (mean +/- SD) in BALF from patients with eosinophilic pneumonia was 12.2 +/- 7.78 micrograms/l which was significantly higher than the concentrations in patients with bronchial asthma not during an attack (1.36 +/- 2.08 micrograms/l) and in healthy control subjects (2.14 +/- 4.62 micrograms/l). These results suggest that local eosinophils in the lungs are activated and degranulated by various stimuli and undergo structural degeneration in eosinophilic pneumonia.

Adult↗

PubMed1992

[A case of gold lung with positive lymphocyte stimulation test to gold, using bronchoalveolar lymphocytes].

Gold lung, a gold-induced pneumonitis, is considered to be caused by hypersensitivity reaction to gold. We performed lymphocyte stimulation test (LST) to determine the response to gold, using lymphocytes obtained by bronchoalveolar lavage (BAL) from a patient with gold lung. A 57-year-old man was admitted with progressive shortness of breath following a skin eruption. He had been receiving weekly sodium gold thiomalate (Shiosol) for rheumatoid arthritis, with a cumulative dose of 485 mg. Chest roentgenogram showed diffuse interstitial infiltrates. LST for the response to gold, using peripheral lymphocytes, was positive. T cell lymphocytosis was observed in BAL, and transbronchial lung biopsy showed lymphocytic alveolitis and granulation tissue in alveolar ducts. From these findings, we diagnosed gold lung. Prednisolone (PSL) was started with an initial dose of 30 mg/day and resulted in a rapid improvement. As the dose of PSL was tapered, the patient's condition deteriorated and he was treated with a maintenance dose of 10 mg PSL. The second BAL revealed persistent lymphocytosis, and LST using bronchoalveolar lymphocytes for response to gold was positive. LST using peripheral lymphocytes was also positive, but was weaker than that using bronchoalveolar lymphocytes. This is the first report in Japan of a positive LST for response to gold, using bronchoalveolar lymphocytes from a patient with gold lung. This case suggests that the presence of activated lymphocytes against gold in the lung is cumulative, and that cell-mediated hypersensitivity is related to gold lung.

Arthritis, Rheumatoid↗

PubMed1991

Relationship between dietary, serum, and tissue levels of carotenoids.

A study was undertaken to assess the utility of the buccal scrape technique for measuring tissue levels of carotenoids in short-term intervention trials and epidemiologic studies. In 14 healthy volunteers a good correlation was found between serum beta-carotene levels and recent dietary intake of beta-carotene as estimated from measured food records. Supplementation with 30 mg/day of beta-carotene for 1 week resulted in a sixfold increase in average serum levels, while serum lycopene concentrations remained constant. Presupplementation levels of beta-carotene and lycopene in the buccal mucosa cells were not correlated with dietary intakes or with serum levels. After supplementation, levels of both carotenoids were found to increase in buccal cells, however, most of this increase was found to be an artifact due to repeated sampling. After correcting for this artifact, beta-carotene was found to increase less than twofold in tissue after supplementation.

Adult↗

PubMed1991

Involvement of transforming growth factor alpha/epidermal growth factor receptor autocrine growth mechanism in an ovarian cancer cell line in vitro.

Although transforming growth factor (TGF) alpha and epidermal growth factor (EGF) receptor (EGFR) autocrine mechanism is widely demonstrated in many kinds of cancers, its biological significances still remain circumstantial. We critically assessed the significance of this mechanism on the growth of an ovarian cancer cell line. Northern blot analysis in polyadenylated RNA isolated from cells by using 32P-labeled pre-TGF alpha, EGRF, and prepro-EGF complementary DNAs as probes revealed that pre-TGF alpha and EGFR but not prepro-EGF gene transcripts were expressed in the cell. TGF alpha and EGFR but not EGF proteins were observed by immunocytochemical stainings, using monoclonal antibodies against human TGF alpha, EGFR, and EGF, respectively. This cell line possessed a class of high affinity EGF receptor by 125I-EGF binding studies; Kd being 2.9 x 10(-10) M and Bmax to be 7.7 x 10(4) sites/cell. As much as 1.12 +/- 0.14 ng (SD; n = 3)/10(7) cells/24 h of TGF alpha was secreted in the conditioned media. These results suggested the expression of a TGF alpha/EGFR autocrine mechanism in this cell line. We, therefore, assessed the biological significance of this mechanism on the growth of this cell line in serum-free monolayer cell cultures. Although 0.1, 1.0, and 10 nM concentrations of TGF alpha did not show significant growth promotion, monoclonal antibodies against TGF alpha and EGFR but not EGF significantly inhibited cell growth. All these data suggested the biological importance of a TGF alpha/EGFR autocrine mechanism on the growth of this cell line in vitro.

Antibodies, Monoclonal↗

PubMed1991

Importance of transforming growth factor alpha/epidermal growth factor receptor autocrine growth mechanism in an ovarian cancer cell line in vivo.

We have elucidated the importance of a transforming growth factor (TGF) alpha and epidermal growth factor receptor autocrine mechanism on the growth of a human ovarian serous cystadenocarcinoma-derived cell line (SHIN-3) in vitro. In this study, we studied the biological significance of this autocrine mechanism in vivo using female athymic nude (nu/nu) mice. We measured the mouse plasma epidermal growth factor and TGF alpha levels by radioimmunoassay and enzyme-linked immunosorbent assay, respectively. Plasma epidermal growth factor concentrations were remarkably decreased by sialoadenectomy (Sx): 410 +/- 65 (SE) pg/ml (n = 10) in intact animals; and undetectable in Sx mice (n = 5). Plasma TGF alpha levels were 90 and 40 pg/ml in intact and in Sx animals, respectively. Ten million SHIN-3 cells inoculated into nu/nu mice formed tumors in 100% of mice, and tumors grew progressively. Implantabilities and tumor growth rates of inoculated cells were not affected by Sx and even by Sx and anti-mouse epidermal growth factor antibody treatment. However, anti-TGF alpha monoclonal antibody (mAb) administered to SHIN-3 cell-inoculated Sx animals drastically reduced the tumor growth. Although 10(7) SHIN-3 cells formed tumors in this group, tumor growth was significantly inhibited by 10 micrograms of anti-TGF alpha mAb given 3 times a week, and growth inhibitions were more by 20 micrograms of anti-TGF alpha mAb. Moreover, as aggressive tumor growth as that in Sx animals was resumed by the cessation of anti-TGF alpha mAb treatments. All these data suggested the biological importance of a TGF alpha/epidermal growth factor receptor autocrine mechanism on the growth of this cell line in vivo.

Animals↗

PubMed1991

Evidence for the involvement of transforming growth factor alpha and epidermal growth factor receptor autocrine growth mechanism in primary human ovarian cancers in vitro.

We examined 35 primary human ovarian adenocarcinomas for the presence of epidermal growth factor (EGF) receptor (EGFR) in plasma membranes from cancer tissues by using 125I-EGF as a ligand. Specific 125I-EGF bindings were observed in 20 (57%) of these 35 cases. Scatchard analysis showed a class of high affinity EGF receptor: Kd 5.0 +/- 1.0 x 10(-10) M; Bmax, 83.3 +/- 12.1 fmol/mg protein (mean +/- SE, n = 20). Northern analysis in polyadenylated RNA from 15 EGFR(+) cancers using pretransforming growth factor alpha (pre-TGF alpha), prepro-EGF complementary DNA, and pE7, a complementary DNA clone of human EGFR, as probes revealed that pre-TGF alpha and EGFR mRNAs but not prepro-EGF mRNA were expressed in all cases examined. Immunocytochemical studies using monoclonal antibodies (mAbs) against TGF alpha, EGF, and EGFR showed that TGF alpha and EGFR but not EGF proteins were present on ovarian cancer cells in all cases. These data suggested a possible TGF alpha/EGFR autocrine mechanism in EGFR(+) ovarian cancers. We, therefore, examined the biological significance of this autocrine mechanism by using primary monolayer cell cultures. In primary cultures from EGFR (+) cancers, TGF alpha added to the culture medium stimulated the [3H]thymidine incorporation dose dependently. Moreover, the addition of mAbs against TGF alpha and EGFR but not EGF inhibited [3H]thymidine incorporation dose dependently in EGFR(+) cancer cells. On the other hand, in primary cultures from EGFR(-) cancers, TGF alpha and anti-TGF alpha, -EGFR, and -EGF mAbs did not show any effects on [3H]thymidine incorporation. All these results suggested the possible crucial role of a TGF alpha/EGFR autocrine growth mechanism in primary human ovarian cancers which express EGFR.

Adenocarcinoma↗

PubMed1991

Superoxide anion increases intracellular pH, intracellular free calcium, and arachidonate release in human amnion cells.

We determined the effects of superoxide anion, produced by addition of xanthine oxidase to hypoxanthine, on the intracellular pH (pHi) and intracellular free calcium concentration ([Ca2+]i) and release of arachidonate in human cultured amnion cells. Superoxide anion induced a prompt increase of pHi and subsequent increase of [Ca2+]i. The evoked pHi was inhibited by pretreatment with anion channel blockers but not affected by omission of extracellular Na+ or addition of amiloride. The increase of [Ca2+]i was inhibited significantly by the absence of extracellular calcium or by the addition of a calcium channel blocker, cobalt. NH4Cl, which can generally increase pHi, also increased [Ca2+]i of amnion cells. But the increase of [Ca2+]i induced by the NH4Cl was significantly less than that induced by the amount of superoxide anion causing a similar increase in pHi. These results show that superoxide anion, crossed through anion channel in membrane, increased [Ca2+]i at least partially via increase of pHi and that the calcium mobilization was dependent on both extracellular and intracellular sources. Superoxide anion induced the release of arachidonate in a dose-dependent manner and this induction was inhibited by omission of extracellular calcium. These data suggest that the release of arachidonate was dependent on the increase of [Ca2+]i. We also determined the viability of cells in the presence of superoxide anion by flow cytometry. Superoxide anion at the levels used in these experiments did not change the percentage of viable cells. These findings suggested that superoxide anion may regulate biological functions in amnion cells via pHi, [Ca2+]i mobilization, and the release of arachidonate without damaging the cells.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

PubMed1991

Length of the human umbilical cord in multiple pregnancy.

The factors controlling the length of the human umbilical cord are uncertain. In the generally accepted 'tension theory', the length of the umbilical cord is proposed to increase the tensile force on it in the uterus. The greatest tensile force is supposed to be fetal movement. If this is so, the length of the umbilical cord should be shorter in multiple pregnancy than in single pregnancy. To examine this possibility we measured the umbilical cord lengths in 3314 singleton births, 82 twins births (164 infants), and 11 triplet or quadruplet births (35 infants). The cord lengths in multiple pregnancies (twins 51.3 cm, triplets and quadruplets 50.1 cm) tended to be shorter than that in singleton pregnancies (57.2 cm). However, no significant difference was found in the ratio of the umbilical cord length to the infant body weight in these groups. Therefore, we conclude that an important factor in determining the cord length is the size of the infant.

Body Weight↗