Biomedical subjects

M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 1,279 records · Page 71Linked to original sources

PubMed1990

Dipalmitoylphosphatidylcholine (L-alpha-lecithin) stimulates prostaglandin E production in human amnion.

The effect of dipalmitoylphosphatidylcholine (DPPC, L-alpha-lecithin), a substance not containing arachidonic acid, on prostaglandin E (PGE) production of amniotic membrane was studied. DPPC (3.125-800 micrograms/ml) stimulated PGE production of amniotic membrane (150-200%), suggesting that lecithin, the major surfactant component, is directly involved in the mechanism of human parturition as a stimulator of PGE production.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1990

A disintegration test for vaginal tablets: comparison with BP test.

To improve the disintegration test for vaginal tablets described in the British Pharmacopoeia (BP), a monitoring apparatus was added, and tested with seven effervescent and five non-effervescent tablets. A tablet was placed on the metal disc of the BP disintegration apparatus, and the guided plate was placed on the tablet. The guided plate moved downward smoothly in a cylinder as the tablet disintegrated. The movement was recorded by using a kymograph. The end-point and process of disintegration of the tablet were automatically recorded and the results obtained suggest that the modified test is a useful tool for the quality control of vaginal tablets.

Female↗

PubMed1990

[A case of pulmonary nocardiosis associated with middle lobe atelectasis].

Pulmonary nocardiosis is a rare disease. We reported a case of pulmonary nocardiosis associated with middle lobe atelectasis. A 66-year-old female was admitted to Saga Medical School Hospital with complaints of fever, productive cough and hemosputum. Nocardia asteroides was isolated from her sputum and bronchial lavage fluid. Administration of sulfamethoxazole-trimethoprim (ST) improved her symptoms and Nocardia asteroides were rapidly eliminated from her sputum. However, she had severe side effects of ST: toxic dermatitis, granulocytopenia and liver dysfunction, whereupon administration of ST was stopped. About two weeks later, Nocardia asteroides appeared again in her sputum. Either netilmicin (NTL) or minocycline (MINO) given consecutively could not eliminate Nocardia asteroides from her sputa. Subsequently a combination therapy of OFLX administration and gentamicin inhalation was tried. This treatment improved her symptoms and eradicated Nocardia asteroides from her sputa completely. In vitro study, ST, MINO and aminoglycosides showed good susceptibility against Nocardia asteroides. In this case, it was revealed that GM inhalation therapy is also very useful for pulmonary Nocardiosis.

Aged↗

PubMed1990

Drosophila proliferating cell nuclear antigen (cyclin) gene: structure, expression during development, and specific binding of homeodomain proteins to its 5'-flanking region.

The genomic and cDNA clones for a Drosophila melanogaster proliferating cell nuclear antigen (PCNA) (cyclin) were isolated and sequenced. The coding sequence for a 260-amino-acid residue polypeptide was interrupted by a single short intron of 60 base pairs (bp), and about 70% of the deduced amino acid sequence of the Drosophila PCNA was identical to the rat and human PCNA polypeptides, with conserved unique repeats of leucine in the C-terminal region. Genomic Southern blot hybridization analysis indicates the presence of a single gene for PCNA per genome. The PCNA mRNA was detected at a high level in adult ovaries, unfertilized eggs, and early embryos and at low levels in the other developmental stages. The major transcription initiation site (cap site) was localized at 89 bp upstream from the ATG codon. Neither a TATA box nor a CAAT box was found within the 600-bp region upstream of the cap site. Clusters of 10 bp of sequence similar to the binding sites for Drosophila proteins containing homeodomains were found in the region from -127 to -413. DNase I footprint analysis revealed that the Drosophila homeodomain proteins coded by even-skipped and zerknüllt genes can specifically bind to these sites. These results suggest that the expression of the PCNA gene is under the control of genes coding for homeodomain proteins.

Amino Acid Sequence↗

PubMed1990

Sulfhydryls on frog skeletal muscle membrane participate in contraction.

To examine the molecular mechanism underlying contractile activation, we studied effects of a sulfhydryl reagent, N-(7-dimethylamino-4-methylcoumarinyl)maleimide (DACM), on twitch, Ag(+)-induced contraction, and K+ and caffeine contractures in single toe muscle fibers of frog. DACM suppressed twitch and Ag(+)-induced contraction, dose dependently, but not caffeine contracture. K+ contracture also was decreased appreciably by exposure to 40 microM DACM for 10 min. DACM elicited no shift of the mechanical threshold or inhibition of resting potential but slightly inhibited action potential. Increase of the fluorescence intensity produced by binding of 10 microM DACM to sulfhydryl groups was depressed by brief pretreatment with 100 microM Ag+. When exposed to 1 mM dithiothreitol (DTT) within 5 s of the rising phase of 5 microM Ag(+)-induced contraction, the fiber rapidly decreased the tension to the resting level. In this case, reapplication of 5 microM Ag+ after washing out DTT elicited a new contraction similar to the first Ag(+)-induced contraction. The second contraction amplitude depended on the time between the onset of the first Ag(+)-induced contraction and DTT application. If DTT was applied after more than 16 s, tension no longer developed on the second exposure to Ag+ or K+. The experiments provide evidence that crucial sulfhydryl groups participate in muscle activation. The possible role of the sulfhydryl group on the transverse tubular membrane in tension development is discussed.

Animals↗

PubMed1990

Dopamine inhibits the arachidonate and prolactin release stimulated by thyrotropin-releasing hormone through an islet-activating protein-sensitive GTP-binding protein in anterior pituitary cells.

Coupling of the dopamine (DA) receptor to the pathway of arachidonate (AA) through the islet-activating protein (IAP)-sensitive GTP-binding (G) protein was examined in primary cultures of anterior pituitary cells. The inhibitions by 1 microM DA of the stimulations of prolactin (PRL) release by 100 nM thyrotropin-releasing hormone and by 10 microM calcium ionophore A23187 were blocked by 100 ng/ml IAP. DA at 1 microM did not inhibit the release of [3H]-AA induced by 100 mU/ml phospholipase A2 (PLA2), but it inhibited the release of PRL induced by 100 mU/ml PLA2. This inhibition was blocked by 100 ng/ml IAP. IAP also blocked the inhibitions by DA of the releases of PRL by 5 microM AA and by 5 microM 5-hydroxyeicosatetraenoic acid. These results suggest that the DA receptor on lactotrophs is coupled to the pathway following the release of AA (lipoxygenase) through the IAP-sensitive G protein.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1990

Induction by tumor necrosis factor-alpha of rapid release of immunoreactive and bioactive luteinizing hormone from rat pituitary cells in vitro.

Tumor necrosis factor-alpha (TNF-alpha) is secreted by activated monocytes and other immune cells. This paper reports studies on the effects of TNF-alpha on the releases of pituitary hormones such as luteinizing hormone (LH), follicle-stimulating hormone, prolactin (PRL) and adrenocorticotropic hormone (ACTH). The addition of recombinant human TNF-alpha (rTNF-alpha) to cultures of pituitary cells resulted in significantly increased releases of gonadotropins, PRL, and ACTH for up to 30 min, but not later. rTNF-alpha, like GnRH, also stimulated the release of bioactive LH. In addition, rTNF-alpha induced production of an interleukin-6 (IL-6)-like molecule by pituitary cells. As IL-6 induces the releases of multiple hormones from pituitary cells, our data suggest that rTNF-alpha may stimulate the releases of multiple pituitary hormones through IL-6 production as well as by its direct action on pituitary cells.

Adrenocorticotropic Hormone↗

PubMed1990

Beta-alanyl-L-histidinato zinc prevents the toxic effect of aluminium on bone metabolism in weanling rats.

The preventive effect of beta-alanyl-L-histidinato zinc (AHZ) on the toxic action of aluminium on bone metabolism was investigated in the femoral diaphysis of weanling rats. Aluminium chloride (5.0, 10.0 and 20.0 mumol A1/100 g body weight) was orally administered for 3 days. The dose of 10.0 and 20.0 mumol A1/100 g caused a significant increase in serum calcium concentration and bone acid phosphatase activity, while bone alkaline phosphatase activity and calcium content were not altered significantly. Moreover, the bone DNA content was significantly decreased by the doses of 10.0 and 20.0 mumol A1/100 g. Meanwhile, the increase in serum calcium concentration caused by the administration of aluminium (20 mumol/100 g) was completely prevented by the simultaneous administration of AHZ (1.0 and 2.5 mg/100 g) for 3 days, although AHZ alone did not have any effect. Also, the effects of aluminium (20.0 mumol/100 g) to increase bone acid phosphatase activity and to decrease the bone DNA content were completely blocked by the simultaneous administration of AHZ (1.0 and 2.5 mg/100 g). AHZ (1.0 and 2.5 mg/100 g) alone had the effect to increase bone DNA content but not bone acid phosphatase activity. The present study indicates that AHZ can prevent the revelation of the toxic effect of aluminium on bone metabolism in rats.

Acid Phosphatase↗

PubMed1990

Effect of the new zinc compound beta-alanyl-L-histidinato zinc on bone metabolism in elderly rats.

The effect of a new zinc compound beta-alanyl-L-histidinato zinc (AHZ) on bone metabolism was investigated in aged rats (30 weeks old). AHZ (1.0, 2.5 and 7.5 mg/100 g body weight) was orally administered to rats 3 times at 24-hour intervals, and the rats were bled 24 h after the last administration. The administration of AHZ (7.5 mg/100 g) did not cause an appreciable alteration of calcium and inorganic phosphorus concentrations in the serum, and zinc, calcium and deoxyribonucleic acid contents in the femoral diaphysis were significantly increased by the administration of AHZ (7.5 mg/100 g). The bone alkaline phosphatase activity was significantly increased by doses of 1.0-7.5 mg AHZ/100 g. These results suggest that AHZ has a stimulatory effect on bone formation and calcification in aged rats.

Administration, Oral↗

PubMed1990

Influence of different types and levels of dietary lipids on liver microsomal mixed function oxidase system in rats.

It has been shown that dietary polyunsaturated fatty acids stimulate the liver microsomal mixed function oxidase system. The influence of different levels of dietary lard, soybean oil and sardine oil on the mixed function oxidase system was investigated in rats. The diet containing 5% sardine oil rich in eicosapentaenoic and docosahexaenoic acids stimulated the mixed function oxidase system, but the diet containing 5% lard in which lard consisted of 10.7% linolenic acid and 1.5% linolenic acid seemed unlikely to stimulate enough the mixed function oxidase system. On the other hand, no definite effects of large doses of dietary lipids, 25% in the diets, on the mixed function oxidase system were observed.

Aminopyrine N-Demethylase↗

PubMed1990

High concentrations of plasma immunoreactive inhibin during normal pregnancy in women.

The plasma inhibin concentrations in 190 normal pregnant women at 5-40 weeks gestation and in 4 puerperal women were measured by a specific RIA for human inhibin. The average plasma inhibin concentrations in pregnant women throughout pregnancy (minimum, 2.25 +/- 0.48 IU/mL at 17 weeks gestation; maximum, 24.15 +/- 6.99 IU/mL at 39 weeks gestation) were much higher than those in nonpregnant women with a normal menstrual cycle (0.46 +/- 0.04 IU/mL in the midfollicular phase and 2.02 +/- 0.47 IU/mL in the midluteal phase). The inhibin concentrations were already high at 5 weeks gestation (7.54 +/- 1.10 IU/mL) and rose to peak at 8-10 weeks gestation. The concentrations then decreased and remained relatively low during 14-30 weeks gestation, but rose again during the third trimester. The inhibin concentrations decreased to undetectable levels after delivery. Immunoreactive inhibin was demonstrated in the corpus luteum and term placental extracts, and the dose-response curves were parallel to an inhibin preparation from human follicular fluid. Immunoreactive inhibin concentrations were also high in both the umbilical vein and artery (7.77 +/- 0.80 and 7.84 +/- 0.78 IU/mL, respectively). These observations suggest that both the corpus luteum and placenta are likely sources of inhibin.

Adult↗

PubMed1990

Effects of Ca2+, Zn2+ and Cd2+ on uridine diphosphate-glucuronyltransferase and beta-glucuronidase activities in rat liver microsomes.

The effect of various metals on uridine diphosphate (UDP)-glucuronyltransferase and beta-glucuronidase activities in rat liver microsomes was investigated. The presence of Mn2+, Cd2+, Zn2+, V5+, Ni2+, Co2+, Cu+ or Ca2+ (20 microM) in the enzyme reaction mixture did not cause a significant alteration of UDP-glucuronyltransferase activity in hepatic microsomes. Of these metals, Zn2+ and Cd2+ (20 microM) caused a remarkable increase in hepatic microsomal beta-glucuronidase activity. Appreciable effects of Zn2+ and Cd2+ on beta-glucuronidase activity were seen at 5.0 microM, and the effects were saturated at 50 microM. Ca2+ (5.0-50 microM) and/or the Ca2(+)-binding protein regucalcin (2.0 microM) did not have an appreciable effect on UDP-glucuronyltransferase and beta-glucuronidase activities in hepatic microsomes. Thus, Zn2+ and Cd2+ uniquely increased beta-glucuronidase activity. The Zn2(+)- and Cd2(+)-induced increase in beta-glucuronidase activity was completely reversed by the presence of an SH group-protecting reagent (dithiothreitol). The response of the microsomal enzyme to Zn2+ and Cd2+ (20 microM) was no longer seen after treatment with 0.2% Triton X-100 [polyoxyethylene(10)octylphenyl ether], indicating that the stimulation by these metals is dependent on membrane association. The present study suggests that, of various metals tested, Zn2+ and Cd2+ can uniquely increase hepatic microsomal beta-glucuronidase activity and that their effect is based on binding to membranous SH groups, beside the enzyme protein.

Animals↗

PubMed1990

Alteration of glucose consumption and adenosine triphosphate content in bone tissue of rats with different ages: the stimulatory effect of zinc.

The alteration in bone metabolism at different ages was investigated by estimating glucose consumption and adenosine triphosphate (ATP) content in a culture system of bone tissue from 3- and 30-week-old rats. The femoral-diaphyseal tissue was removed and cultured for periods up to 48 h in Dulbecco's Modified Eagle Medium. Bone tissue was incubated at 37 degrees C in 5% CO2/95% air in a medium containing either vehicle and zinc sulfate (10(-6) - 10(-4) M). The medium glucose consumed by bone tissue clearly increased in a 48 h-culture in 3-week-old rats, while the increase in 30-week-old rats was slight. The presence of zinc sulfate (10(-6) and 10(-5) M) caused a significant increase in bone glucose consumption in 3- and 30-week-old rats. ATP content in cultured bone tissue from 30-week-old rats fairly fell in comparison with that from 3-week-old rats. Bone ATP contents in 3- and 30-week-old rats were significantly increased by the presence of zinc (10(-4) M). The present findings suggest that bone energy metabolism deteriorates with increasing age, and that zinc has a stimulatory effect in elderly rats.

Adenosine Triphosphate↗

PubMed1990

Hepatic calcium-binding protein regucalcin decreases Ca2+/calmodulin-dependent protein kinase activity in rat liver cytosol.

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on cytosolic Ca2+/calmodulin-dependent protein kinase activity was investigated. The increase in cytosolic Ca2+/calmodulin-dependent protein kinase activity with passage of incubation time was clearly prevented by the presence of regucalcin (1.0 microM). An appreciable effect of regucalcin was seen at 0.5 microM. The cytosolic Ca2+/calmodulin-dependent protein kinase activity was fairly increased by increasing concentrations of added Ca2+ (0.25-1.0 mM). This increase was clearly blocked by the presence of regucalcin (1.0 microM). The inhibitory effect of regucalcin on the protein kinase activity was also seen with varying concentrations of calmodulin (2.5-15 micrograms). In the presence of regucalcin (1.0 microM), trifluoperazine (50 microM), an antagonist of calmodulin, significantly decreased the cytosolic Ca2+/calmodulin-dependent protein kinase activity. These results suggest that regucalcin can regulate the Ca2(+)-calmodulin effect in liver cytosol.

Animals↗

PubMed1990

Regucalcin-induced Ca2+ release from rat liver microsomes: the effect is inhibited by heparin.

The effect of heparin on the calcium-binding protein regucalcin-stimulated Ca2+ release from rat liver microsomes was investigated. Ca2+ release was assayed by the method of Millipore filtration to estimate microsomal 45Ca2+ accumulation following the addition of 10 mM adenosine triphosphate. The addition of regucalcin (1.0 microM) or inositol 1,4,5-trisphosphate [Ins(1,4,5)P3; 1.0 microM] stimulated 45Ca2+ release from rat liver microsomes. These effects were completely inhibited by the presence of heparin (10.0 micrograms/ml). Regucalcin did not enhance the effect of Ins(1,4,5)P3. These results suggest that regucalcin affects 45Ca2+ release involved in Ins(1,4,5)P3 action in rat liver microsomes.

Animals↗

PubMed1990

Disintegration test to measure lot-to-lot variations of vaginal tablets.

Attempts were made to investigate the disintegration test for vaginal tablets. Disintegration tests were done for four different commercial vaginal tablets (three lots each) by the watch glass method and Japanese Pharmacopoeia (JP) disintegration method, and the resulting profiles were compared to those by the modified British Pharmacopoeia (BP) method on a point of lot-to-lot variation of the disintegration times. The disintegration time of every tablet by the modified BP method was longest, followed by the watch glass method, and finally by the JP disintegration method. The results for lot-to-lot differences in disintegration times by the modified BP method were similar to those by the watch glass method. However, such lot-to-lot differences as found by the modified BP method and watch glass method were not always observed by the JP disintegration method. It was concluded from these results that the modified BP method was most suitable for investigating lot-to-lot differences in the disintegration of vaginal tablets.

Administration, Intravaginal↗

PubMed1990

Interleukin 6 possibly induced by interleukin 1 beta in the pituitary gland stimulates the release of gonadotropins and prolactin.

The abilities of recombinant human interleukin 1 (IL-1) and IL-6 to induce release of FSH, LH and PRL from rat pituitary cells in vitro were examined. IL-1 and IL-6 induced significant releases of FSH, LH and PRL within 3 h. The extents of release of these compounds induced by IL-1 and IL-6 were similar to those induced by GnRH and TRH. Rat anterior pituitary cells released IL-6 spontaneously, and its release was enhanced by IL-1 beta. This effect of IL-1 beta was inhibited significantly by a rabbit anti-IL-1 beta antiserum. These findings suggest that IL-1 induced the release of IL-6 from rat pituitary, and that the released IL-6 stimulated the secretions of FSH, LH and PRL.

Animals↗

PubMed1990

Interleukin 1 beta and tumour necrosis factor alpha stimulate the release of gonadotropin-releasing hormone and interleukin 6 by primary cultured rat hypothalamic cells.

The abilities of recombinant human interleukin 1 beta and tumour necrosis factor alpha to induce release of GnRH and interleukin 6 from primary culture of rat hypothalamic cells were examined. The effect of estradiol on the release of interleukin 6 by these cells was also tested. Both interleukin 1 beta and tumour necrosis factor alpha caused significant stimulation of GnRH secretion from the hypothalamic cells within 5 min. The hypothalamic cells secreted interleukin 6 spontaneously, and their secretion over 24 h was stimulated dose-dependently by interleukin 1 beta, tumour necrosis factor alpha and estradiol. These results suggest that interleukin 1 beta and tumour necrosis factor alpha stimulate the secretions of GnRH and interleukin 6 in the hypothalamus, and that these cytokines may be involved in the mechanism of GnRH secretion in the hypothalamus.

Animals↗