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Biomedical subjects

N Suganuma

Publications and source records attributed to N Suganuma.

At least 91 records · Page 5Linked to original sources
PubMed1992

Design of a long-acting follitropin agonist by fusing the C-terminal sequence of the chorionic gonadotropin beta subunit to the follitropin beta subunit.

Follitropin (FSH) is a pituitary glycoprotein hormone that is essential for the development of ovarian follicles and testicular seminiferous tubules. FSH is used clinically to stimulate follicular maturation for in vitro fertilization and treatment of anovulatory women. One issue regarding the clinical use of FSH is its short half-life in the circulation. To address this point, we constructed chimeric genes containing the sequence encoding the C-terminal peptide of the chorionic gonadotropin beta subunit (CG beta) fused to the translated sequence of the human FSH beta subunit (FSH beta). This region of CG beta is important for maintaining the prolonged plasma half-life of human CG dimer. The presence of the C-terminal peptide sequence did not significantly affect assembly of FSH beta with the alpha subunit or secretion of the dimer. In vitro receptor binding and steroidogenic activity of dimer bearing the FSH beta-C-terminal peptide chimera were the same as wild-type FSH. However, both the in vivo potency and half-life in circulation of the dimer bearing either one or two C-terminal peptide units were enhanced. Dimers containing FSH beta-CG beta chimeras could serve as potent FSH agonists for clinical use, and the present strategy may have wide applications for enhancing the in vivo half-life of diverse proteins.

Animals↗
PubMed1992

Menotropin stimulation after prolonged gonadotropin releasing hormone agonist pretreatment for in vitro fertilization in patients with endometriosis.

Two protocols were scheduled for in vitro fertilization and embryo transfer (IVF-ET) in patients with various stages of endometriosis who were resistant to conventional therapies. In the ultralong protocol (21 patients), gonadotropin releasing hormone agonist (Gn-RHa) was administered for at least 60 days prior to ovarian stimulation along with menotropin until human chorionic gonadotropin was injected. In the long protocol (11 patients), Gn-RHa was started at the midluteal phase and exogenous gonadotropin was commenced between the third and the seventh day of the menstrual cycle after pituitary suppression. The estradiol response and the number of retrieved oocytes, fertilized oocytes, cleaved oocytes, and transferred embryos were similar in both groups but the clinical pregnancy rate per transfer was superior in the ultralong protocol (67 vs 27%). The miscarriage rate was 14% (2/14) in the ultralong protocol. Prolonged Gn-RHa suppression of ovarian function before superovulation may overcome some causes of infertility in patients with endometriosis.

Adult↗
PubMed1992

Gonadotropin induces expression of c-fos and c-jun genes in rat ovaries.

It has been shown that the expression of protooncogenes, c-fos and c-jun, induced by growth factors and hormones plays important roles in cellular proliferation, tissue differentiation and transcription of certain genes. Since gonadotropin stimulates ovarian steroidogenesis and cellular proliferation, we investigated whether gonadotropin affects the expression of c-fos and c-jun genes in rat ovaries. The expression of mRNA coding side chain cleavage enzyme (P450scc), the rate limiting enzyme in ovarian steroidogenesis was also studied. The effect of gonadotropin was examined in female rats whose gonadotrophs were medically ablated by GnRH agonist (TAP-144-SR). After intravenous administration of pregnant mare's serum gonadotropin (PMSG:30 IU/rat), their ovaries were dissected out at various time intervals and total RNA was extracted. Changes in the levels of c-fos, c-jun and P450scc mRNAs were determined by Northern blot analysis. The levels of c-fos and c-jun mRNAs increased rapidly and transiently with the peak levels at 15 min after PMSG administration. The levels of both mRNAs were decreased by 30 to 60 min. On the other hand, the levels of P450scc mRNA started to increase 60 min after PMSG. These results indicate that gonadotropin-induced increase in the expression of c-fos and c-jun genes may play important roles in mediating the action of gonadotropin on the ovaries.

Actins↗
PubMed1992

Source of prolactin in human follicular fluid.

To analyze whether prolactin (PRL) in human follicular fluid (FF) is synthesized locally or derived from the circulation, PRL concentrations of plasma and FF were determined in the patients after ovarian stimulations. The amounts of PRL messenger ribonucleic acid (mRNA) in the follicular tissues during different menstrual phases were also determined. The FF PRL concentration was correlated positively with plasma PRL and highest estradiol levels during the stimulatory cycle. No PRL mRNA sequence was detected in the RNAs extracted from follicles at any stage in the menstrual cycle, although beta-actin mRNA was detected in all samples. In a comparison with pituitary RNA, the PRL mRNA concentration in ovarian follicular tissues seemed to be 10,000 times less than that in the pituitary. These results suggest that FF PRL may not be synthesized locally, but derived from the pituitary via the circulation through passive diffusion, and thus regulated by estrogen.

Actins↗
PubMed1991

Post-translational processing and secretory pathway of human atriopeptin in rat pheochromocytoma cells.

Atriopeptin (AP) is expressed in several tissues with each tissue capable of specific differences in processing of the prohormone (pro-AP) to mature low molecular forms of the peptide. Since pro-AP has low biological activity, processing into mature AP is a critical activation event. This observation prompted us to study whether granule storage or regulated secretion of AP is essential for cleavage of mature peptide. We examined the processing of AP in adrenal medulla derived cells, using the rat pheochromocytoma cell line (PC12 cell) stably transfected with a genomic human AP DNA in the presence and absence of nerve growth factor (NGF), and also examined the mechanism of AP secretion and compared the results with those obtained using transfected chinese hamster ovary cells (CHO cells). The amount of prohormone was 5-10 fold higher than that of low molecular form of AP in the transfected PC12 cells. This ratio was essentially unchanged in differentiated PC12 cells after NGF treatment of the cells. Potassium depolarization of the transfected PC12 cells caused a 5-fold increase in AP release into the medium primarily as the intact prohormone. On the other hand, transfected CHO cells only exhibited constitutive AP release which is non-response to depolarization. These results suggest that the AP prohormone is sorted into secretory granules as the prohormone in PC12 cells and undergoes regulated release in response to depolarization indicating granule storage or release is not the critical determinant of AP prohormone cleavage.

Adrenal Gland Neoplasms↗
PubMed1991

Suckling stimulates the expression of vasoactive intestinal polypeptide gene in rats.

The effect of suckling on vasoactive intestinal polypeptide (VIP) gene expression in the hypothalami was studied during the postpartum period in rats. Female rats were divided into two groups immediately after delivery. In one group, a mother was housed with 8 pups, and in the other, without any pups. The former group was named S(+) and the latter S(-). On days 0, 3, 6, 9 and 12 after delivery, the mothers were killed by decapitation. Hypothalamic VIP mRNA was measured by RNA dot hybridization. Although the VIP mRNA level showed no significant change after delivery in the S(-) group, VIP mRNA in the S(+) group on days 6, 9 and 12 increased to 1.6, 3.5 and 2.1 times higher than the level observed on day 0, respectively. These results suggest that suckling induces the synthesis of VIP after 6 postpartum days.

Actins↗
PubMed1989

Elimination of disulfide bonds affects assembly and secretion of the human chorionic gonadotropin beta subunit.

Human chorionic gonadotropin (hCG) consists of two noncovalently joined alpha and beta subunits similar to the other glycoprotein hormones. To study the function of the individual disulfide bonds in subunit assembly and secretion, site-directed mutagenesis was used to convert the 12 cysteine (Cys) residues in the beta subunit of hCG to either alanine or serine. Both cysteines of proposed disulfide pairs were also mutated. These mutant hCG beta genes were transfected alone or together with the wild-type alpha gene into Chinese hamster ovary cells. Only 3-10% assembly could be achieved with derivatives containing single Cys mutations at positions 26, 110, 72, and 90, whereas no assembly was detected with the other 8 mutants. However, double mutations of pairs 26-110 or 23-72 showed increased dimer formation (11 and 36%, respectively). The secretion rate of individual mutants varied significantly. Whereas the Cys-23 and 72 mutants were secreted normally (t1/2 = 140-190 min), the Cys-26 mutant was secreted faster (t1/2 = 70 min), and the other 9 mutants were secreted slower (t1/2 = 280-440 min); mutations of both Cys at 26 and 110 caused much faster secretion (t1/2 = 34 min). Although the secretion rate of these mutants differed, they were quantitatively recovered in the medium except for mutant Cys-88, Cys-23-72, and Cys-34-88 (40, 55, and 10% secreted, respectively). Thus, interruption of any disulfide bond in the hCG beta subunit alters the structure sufficiently to block dimer formation and in some cases slow secretion, although the stability for most of the mutant hCG beta subunits is not greatly affected. The data indicate that interruption of any hCG beta disulfide bond generates different structural forms that are unable to assemble with the alpha subunit, and that the structural requirements for stability and assembly are different.

Animals↗
PubMed1989

Patterns of alternative splicing of fibronectin pre-mRNA in human adult and fetal tissues.

Alternative splicing of fibronectin pre-mRNA at two distinct regions, termed ED-A and IIICS, was investigated with human adult and fetal tissues by the nuclease S1 protection assay. A clear tissue specificity was observed in the splicing pattern at the ED-A region. More ED-A+ than ED-A- mRNAs were identified in lung, whereas ED-A- mRNAs were predominantly expressed in liver. Endometrium contained nearly equal amounts of ED-A+ and ED-A- mRNAs. The splicing pattern at the ED-A region was also different between adult and fetal liver but not between adult and fetal lung. Tissue type specific splicing was also observed at the IIICS region. Although the mRNA species containing the complete IIICS sequence comprised 40-65% of the total fibronectin mRNAs irrespective of tissue types, expression of the mRNA species lacking a part or all of the IIICS sequence was more pronounced in adult liver than in other tissues including fetal liver. These results strongly suggest that the alternative splicing of fibronectin pre-mRNA in vivo is regulated in a tissue type specific manner at both the ED-A and IIICS regions and that it is developmentally regulated in liver but not in lung. On the basis of these and other observations reported previously, a possibility that a part of the fibronectins synthesized and secreted by hepatocytes is deposited in the tissue matrix is discussed.

Adult↗
PubMed1989

The ontogeny of growth hormone in the human fetal pituitary.

To examine the ontogeny of growth hormone synthesis and secretion in human fetus, growth hormone messenger ribonucleic acid was measured in 11 pituitaries from fetuses of 16 to 27 weeks of gestation by hybridization of cytosol ribonucleic acid with complementary deoxyribonucleic acid labeled with phosphate 32. Pituitary growth hormone content and serum growth hormone, thyroxine, and cortisol concentrations were assessed by radioimmunoassay. Growth hormone messenger ribonucleic acid content in the fetal pituitary increased from the early midtrimester, reaching a level 15.3 times higher at 27 weeks of gestation than the value at 16 weeks. However, growth hormone content in the pituitary showed no evident change during 16 to 21 weeks of gestation and started to increase after 22 weeks. Serum concentration of growth hormone was variable but always greater than 50 ng/ml, and the maximal level was observed at 20 weeks of gestation (141 ng/ml). Although serum thyroxine concentration in the fetuses showed no correlation with pituitary growth hormone content or serum growth hormone concentration, serum concentration of cortisol was correlated positively with growth hormone content in the fetal pituitary. These results suggest that the maturation of the growth hormone synthesis and secretion system in the fetal pituitary occurs after 22 weeks of gestation and that cortisol may play some role in the ontogenesis of growth hormone.

Fetal Blood↗
PubMed1989

Mutagenesis and chimeric genes define determinants in the beta subunits of human chorionic gonadotropin and lutropin for secretion and assembly.

Chorionic gonadotropin (CG) and lutropin (LH) are members of a family of glycoprotein hormones that share a common alpha subunit but differ in their hormone-specific beta subunits. The glycoprotein hormone beta subunits share a high degree of amino acid homology that is most evident for the LH beta and CG beta subunits having greater than 80% sequence similarity. However, transfection studies have shown that human CG beta and alpha can be secreted as monomers and can combine efficiently to form dimer, whereas secretion and assembly of human LH beta is less efficient. To determine which specific regions of the LH beta and CG beta subunits are responsible for these differences, mutant and chimeric LH beta-CG beta genes were constructed and transfected into CHO cells. Expression of these subunits showed that both the hydrophobic carboxy-terminal seven amino acids and amino acids Trp8, Ile15, Met42, and Asp77 together inhibit the secretion of LH beta. The carboxy-terminal amino acids, along with Trp8, Ile15, Met42, and Thr58 are implicated in the delayed assembly of LH beta. These unique features of LH beta may also play an important role in pituitary intracellular events and may be responsible for the differential glycosylation and sorting of LH and FSH in gonadotrophs.

Amino Acid Sequence↗
PubMed1989

Regulation of prolactin gene expression during early pregnancy in rats.

We have shown that administration of estrogen which increases prolactin (PRL) synthesis in the rat may be mediated by an increase in poly [adenosine diphosphate ribose (ADP-ribose)] synthesis. Present investigation was attempted to study whether poly (ADP-ribose) synthesis is involved in rat PRL gene expression during early pregnancy. Anterior pituitaries were obtained on days 0, 2, 4, 6, 8, 10 and 12 of pregnancy (group C). Another group of pregnant rats was given nicotinamide, an inhibitor of poly (ADP-ribose) synthesis twice a day intra-peritoneally from day 0 to the day of sacrifice (group N). Serum estradiol (E2) concentration was determined by radioimmunoassay. PRL mRNA was measured by cytoplasmic dot hybridization using 32P-labeled cDNA. Poly (ADP-ribose) synthesis was assessed by incubating purified nuclei with 14C-nicotinamide adenine dinucleotide. The serum concentration of E2 increased between days 2 and 4, and on day 6 it decreased to the level of day 0. It remained low until day 12. No difference in the serum E2 level was observed in groups C and N. In group C, PRL mRNA increased from day 2 and remained high until day 8. In group C, poly (ADP-ribose) synthesis increased between days 2 and 4, decreased on day 6 to the level of day 0, and thereafter gradually increased until day 10. Administration of nicotinamide abolished the increase in poly (ADP-ribose) synthesis observed in group C during early pregnancy. In group N, the increase in PRL mRNA was completely suppressed. It is suggested that the increase in PRL mRNA in early pregnancy may be mediated by increased poly (ADP-ribose) synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Clinical study of the anti-calculus effect of a dentifrice containing sodium polyphosphate].

A double-blind clinical study was conducted to evaluate the effect of a tartar-control dentifrice containing 1% sodium polyphosphate as tartar control agent compared with dentifrice A containing 5% sodium pyrophosphate and a placebo dentifrice. One hundred forty-eights who continued to have a degree of calculus formation after using a regular dentifrice containing no tartar control agent for 1 month in the pretest, were stratified randomly on the basis of pretest, calculus score, age and sex into 3 homogeneous groups. All subjects who received initial prophylaxis were provided the assigned dentifrice and toothbrush. No instructions regarding frequency or method of toothbrushing were allowed. Assessment of supragingival calculus was made at 4 and 12 weeks using the calculus scoring procedure proposed by Volpe et al. Side effects such as oral irritation, ablation of oral mucosa and discoloration of teeth caused by dentifrices were also diagnosed after 12 weeks of use. The following results were obtained in this study. 1. The test dentifrice had reduced (P less than 0.01) supra-gingival calculus significantly more than dentifrice A and the placebo at 12 weeks. 2. A significant reduction (P less than 0.01) was observed when dentifrice A was compared with the placebo dentifrice. 30.1% reduction was obtained using the test dentifrice and 9.0% reduction using dentifrice A when assessed in subjects who had a pretest VMI score of more than 6.0. 3. No side effects caused by the dentifrice which contained sodium polyphosphate were observed.

Dental Calculus↗
PubMed1989

Effects of pregnancy, delivery and lactation in hyperprolactinemia with prolactin producing pituitary adenoma.

The effects of pregnancy, delivery and lactation on changes in serum prolactin (PRL) values were investigated in patients with hyperprolactinemia. Thirty-seven patients with hyperprolactinemia who wished to become pregnant were treated by transsphenoidal surgery, bromocriptine therapy, or a combination of the two. In 33 patients whose pre-pregnancy serum PRL concentration exceeded 30ng/ml, only in two did serum PRL return to the normal range below 30ng/ml after pregnancy, delivery and lactation. However, the serum PRL concentration was decreased in 28 patients. When classified according to the pre-pregnancy serum PRL concentrations, PRL less than or equal to 100 (Group A), 100 less than PRL less than or equal to 200 (Group B) and 200 less than PRL (Group C), patients with the greatest pre-pregnancy serum PRL concentration showed the greatest reduction. The ratios of post-pregnancy serum PRL to pre-pregnancy PRL in group A, B and C were 91.4 +/- 22.1%, 81.5 +/- 7.0% and 65.0 +/- 6.5% (Mean +/- SE), respectively. Group C with the highest pre-pregnancy serum PRL concentration consisted almost entirely of patients with macroadenoma. Thus, the reduction in serum PRL after pregnancy, delivery and lactation was considered to be the result of a decrease in the size of the adenoma due to adenoma enlargement over the sella turcica through the estrogen effects during pregnancy, and from impairment of pituitary circulation.

Adenoma↗
PubMed1986

Effect of estrogen on prolactin mRNA in the rat pituitary. Analysis by in situ hybridization and immunohistochemistry.

The effect of estrogen on prolactin (PRL) synthesis at a single-cell level was studied by in situ hybridization and immunohistochemistry. Long-term estrogen treatment increased PRL-containing cells from 10-20% of total cell population to 80-90%, as revealed by immunohistochemistry. PRL mRNA containing cells also increased in a similar fashion. Moreover, cytoplasmic PRL mRNA expressed as the number of silver grains per cell increased 4- to 5-fold by estrogen. These results suggest that long-term estrogen treatment causes not only PRL cell proliferation but also an increase in PRL mRNA in a single cell.

Animals↗
PubMed1986

Ontogenesis of pituitary prolactin in the human fetus.

To study the ontogenesis of PRL synthesis and secretion in the human fetus, PRL mRNA was measured in 12 pituitaries from fetuses of 16-27 weeks of gestation by hybridization of cytosol RNA with 125I-labeled single stranded complementary DNA (cDNA). Pituitary PRL content and serum PRL concentration were assessed by RIA. Pituitary weight increased with fetal age, ranging from 12 mg at 16 weeks of gestation to 41 mg at 27 weeks. The increased weight was due to an increase in cell number. PRL mRNA content did not change during weeks 16-20 of gestation. However, it increased rapidly after 21 weeks, reaching 11.5 times the 16-20 week value at 27 weeks. Pituitary PRL content was constant at a low level until 21 weeks, but thereafter it increased markedly. The increase was greater than that in PRL mRNA, and therefore, the PRL to PRL mRNA ratio was 10-fold greater at 27 weeks of gestation. Serum PRL concentrations also gradually increased after 21 weeks of gestation. These results indicate that marked increases in fetal pituitary PRL synthesis and release occur after 21 weeks of gestation.

Base Sequence↗
PubMed1986

Measurement of human prolactin messenger RNA in decidual tissues using complementary DNA probe cloned in M13mp9 bacteriophage.

A human prolactin (PRL) cDNA clone was digested with restriction enzyme Pst I and the resultant fragments were cloned into bacteriophage M13mp9. Single stranded recombinant DNAs having a coding strand of the PRL cDNA were selected by hybridization with 125I-labeled PRL mRNA obtained from human prolactinoma tissue. One of the single stranded recombinant DNAs was purified by agarose gel electrophoresis and labeled with 125I to a specific activity of 1.4 X 10(8) cpm per microgram of DNA. The probe could be successfully used in RNA dot hybridization. Analysis of poly (A) RNAs from prolactinoma, liver and placental tissues revealed that this probe was specific to PRL mRNA sequence. Hybridization of poly (A) RNA from decidual tissue to this probe revealed the presence of PRL mRNA sequence. However, PRL mRNA in decidua was at least 20,000 times less than that in pituitary prolactinoma.

Cloning, Molecular↗