Search PubMed⌕ Search

Biomedical subjects

K Niwa

Publications and source records attributed to K Niwa.

At least 163 records · Page 9Linked to original sources
PubMed1994

[Evaluation of the effects of vibro-acoustic stimulation test on the fetus during labor under epidural analgesia and evidence of its safety by way of auditory brainstem response].

This study was undertaken to elucidate the effects of epidural analgesia on vibro-acoustic stimulation test (VAST) during normal labor and auditory brainstem response (ABR) in fifty full term parturients without any complication. The safety of VAST in relation to the ABR of neonates was also studied. The results were as follows, 1) There were some changes in CTG monitoring in five cases (10%) in the 10 minutes after epidural analgesia. However, these changes were not ominous signs but all related to the coiling of the cord, as previously reported. 2) The ABR latency-intensity curve (audio-function of the newborn infants) revealed no hazardous change in VAST-loaded infants or in the controls. The response threshold was 10dB in this study. The application of VAST to the parturients under epidural analgesia was therefore not only harmless to the fetuses but also a useful way to evaluate fetal well-being.

Acoustic Stimulation↗
PubMed1993

Fibrinogen Mitaka II: a hereditary dysfibrinogen with defective thrombin binding caused by an A alpha Glu-11 to Gly substitution.

A new type of A alpha Glu-11 to Gly substitution has been identified in a congenitally abnormal fibrinogen, fibrinogen Mitaka II, derived from a 14-year-old female suffering from easy bruising since childhood. Plasma of the patient and fibrinogen purified therefrom were found to clot slowly by thrombin but in a normal fashion by ancrod, a thrombin-like snake venom enzyme. The ancrod-clotted fibrin gels were normally solid and turbid, whereas the thrombin-clotted gels were initially fragile and transparent but became gradually normalized during further incubation. On reverse-phase high-performance liquid chromatography, there was an additional peptide group eluted distinctly later than the corresponding normal fibrinopeptide A in the clot-liquor of the patient's samples. Sequence analysis of these aberrant peptides and isolated A alpha chains of the patient's fibrinogen showed that Glu at position 11 of the abnormal A alpha chain had been replaced by Gly. Studies using 125I-labeled thrombin showed that the binding with thrombin was evidently reduced for her fibrinogen and the aberrant fibrinopeptide A as compared with that for the normal controls, indicating that A alpha Glu-11 may be critical for the fibrinogen-thrombin interaction. Indeed, A alpha Glu-11 of fibrinogen has recently been proposed to stabilize the local conformation, including the beta-turn, and to form a salt bridge between its side-chain carboxyl group and the guanidino group of Arg-173 of thrombin based on crystallographic analyses using analogs of fibrinopeptide A complexed with thrombin (Stubb et al, Eur J Biochem 206:187, 1992 and Martin et al, J Biol Chem 267:7911, 1992).

Adolescent↗
PubMed1993

A new type of congenital dysfibrinogen, fibrinogen Bremen, with an A alpha Gly-17 to Val substitution associated with hemorrhagic diathesis and delayed wound healing.

We have identified a new type of A alpha Gly-17 to Val substitution in a congenital dysfibrinogen, fibrinogen Bremen, derived from a 15-year-old boy having manifested easy bruising and delayed wound healing. The functional abnormality was characterized by altered fibrin monomer polymerization, which became evident by increasing the salt concentration and pH. A synthetic tetrapeptide with a sequence of the amino-terminal segment of normal fibrin alpha-chain, Gly-Pro-Arg-Val, substantially inhibited polymerization of both normal and the patient-derived fibrin monomers. A synthetic tetrapeptide with the Bremen type sequence of Val-Pro-Arg-Val inhibited polymerization of the patient's fibrin monomers partially at a peptide: fibrin monomer molar ratio of 4,000:1, and that of normal one at a much higher ratio of 10,000:1. Likewise, a synthetic peptide Ala-Pro-Arg-Val with a replacement of the Gly residue by another aliphatic amino acid Ala inhibited similarly the patient's fibrin monomer polymerization. Thus, the hypothetical two-pronged socket-like structure consisting of the alpha-amino group of the amino-terminal Gly and the guanidino group of an Arg at position 3 of the normal fibrin alpha-chain seems to be restored considerably in the mutant fibrin alpha-chain at low ionic strengths and pH's, despite the replacement of the amino-terminal Gly by another aliphatic amino acid Val.

Adolescent↗
PubMed1993

Effects of different protein supplements in fertilization medium on in vitro penetration of cumulus-intact and cumulus-free bovine oocytes matured in culture.

Bovine oocytes matured in culture were inseminated with frozen-thawed spermatozoa in BO medium containing 5 mM-caffeine, 10 mug/ml of heparin and different protein supplements at various concentrations. When cumulus-enclosed oocytes were inseminated, no significant differences were observed in the penetration rates (89 to 100%) between media with and without protein supplements and among the different concentrations of each protein supplement, except for 20% calf serum (CS), in which the penetration rate decreased drastically (43%). Notably higher incidences of polyspermy were obtained in medium with FCS (75 to 86%) than with either no supplement (25%) or with BSA (20 to 24%) and CS (13 to 49%). On the other hand, there was almost no penetration of cumulus-free oocytes in the nonsupplemented control medium. Concentration-dependent increases in penetration and polyspermy occurred with BSA, FCS and CS supplementation. A high concentration (5%) of FCS yielded a high incidence (97%) of polyspermy. A decrease in the penetration of cumulus-enclosed oocytes was observed when spermatozoa were capacitated with a high concentration (20%) of CS; difficulty of sperm penetration of cumulus-free oocytes occurred when the capacitation medium lacked protein supplementation; and an increased rate of polyspermy was observed following supplementation with FCS in both cumulus-enclosed and cumulus-free oocytes after insemination with spermatozoa from 5 different bulls.

Journal Article↗
PubMed1993

Glucose requirement at different developmental stages of in vitro fertilized bovine embryos cultured in semi-defined medium.

Three experiments were conducted in which 2-cell bovine embryos were prepared from oocytes, obtained from abattoir ovaries, by in-vitro maturation for 22 to 24 hours, followed by exposure to spermatozoa for 8 hours and culture for 40 hours within the cumulus. The cumulus cells were then removed, and the cleaved embryos were cultured for a further 120 hours or longer, in the presence or absence of glucose, pyruvate and lactate. Very few embryos developed in the complete absence of energy substrates. Lactate and pyruvate, alone or combined, supported development to the 8-cell stage, but pyruvate was required to support development to the morula stage (Experiment 1). When present throughout culture or when added at 48 or 96 hours postinsemination, 5.56 mM glucose was detrimental to development (Experiments 1 and 2). However, when added at 120 hours postinsemination, 5.56 mM glucose improved development to the blastocyst and expanded blastocyst stages, compared with no glucose or 11.12 mM glucose (Experiment 3).

Journal Article↗
PubMed1993

Blockade of nitric oxide synthesis in rats strongly attenuates the CBF response to extracellular acidosis.

We tested the hypothesis that the CBF response to extracellular acidosis is mediated by nitric oxide (NO). A closed cranial window, superfused with artificial CSF (aCSF), was implanted over the parietal cortex in anesthetized and ventilated Wistar rats. Regional cerebral blood flow (rCBF) was measured continuously with laser-Doppler flowmetry (LDF). The reaction of rCBF to hypercapnia (PaCO2 from 30.5 +/- 1.8 to 61.3 +/- 5.8 mm Hg by adding CO2 to the inspiratory gas) was 2.9 +/- 1.4%/mm Hg, and the reaction of rCBF to H+ (superfusion of acidic aCSF, pH 7.07 +/- 0.05) was 101.7 +/- 24.7%/pH unit. The regional NO synthase (NOS) activity was blocked by superfusing aCSF containing 10(-3) M N omega-nitro-L-arginine (L-NA, n = 10). After 30 min of L-NA superfusion, rCBF was reduced to 80.1 +/- 6.5% of baseline, and the rCBF responses to hypercapnia (PaCO2 from 30.9 +/- 2.9 to 58.8 +/- 7.7 mm Hg) and extracellular acidosis (aCSF pH 7.08 +/- 0.06) were reduced to 0.8 +/- 1.1%/mm Hg and 10.1 +/- 23.0%/pH unit, respectively (both p < 0.001). This effect was stereospecific since aCSF containing 10(-3) M N omega-nitro-D-arginine affected neither baseline rCBF nor the response to H+ (n = 5). The NOS blockade did not affect the vasodilatation by the NO donor sodium nitroprusside (n = 5, 114.3 +/- 25.1% before vs. 130.2 +/- 24.7% after NOS blockade). The results confirm the involvement of NO in the CBF reaction to hypercapnia and demonstrate for the first time that NOS blockade also strongly attenuates the H+ response of the cerebral vasculature.(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1993

Effects of phosphate, energy substrates, and amino acids on development of in vitro-matured, in vitro-fertilized bovine oocytes in a chemically defined, protein-free culture medium.

Bovine oocytes that had been matured and fertilized in vitro were cultured in a simple, chemically defined, protein-free medium (mTLP-PVA). When the medium was supplemented with 19 amino acids, development to the 8-cell (14-20% vs. 38-46%), morula (0-6% vs. 27-32%), and blastocyst (0-1% vs. 9-13%) stages 96, 144, and 192 h after insemination, respectively, was significantly greater in the absence than in the presence of glucose (5.56 mM) regardless of the presence of phosphate (1.05 mM). However, blastocyst development was difficult in medium with any combination of glucose and phosphate without amino acids. In mTLP-PVA with amino acids and different concentrations of phosphate, the highest proportions of embryos reaching the > or = 8-cell (56%), morula (44%), and blastocyst (24%) stages were obtained at a 0.35 mM concentration. When lactate and pyruvate were omitted from mTLP-PVA (mT-PVA) supplemented with amino acids and 0.35 mM phosphate, the first cleavage was completely inhibited. Although lactate or pyruvate alone could support blastocyst development to a limited extent (10-15%), a significantly higher proportion (22%) of blastocysts was obtained in medium with both lactate (10 mM) and pyruvate (0.5 mM).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1993

Enhancing effects of estrogens on endometrial carcinogenesis initiated by N-methyl-N-nitrosourea in ICR mice.

The present study was undertaken to examine the effects of estrogens, such as estrone (E1), 17 beta-estradiol (E2) and estriol (E3), on endometrial carcinogenesis initiated by N-methyl-N-nitrosourea (MNU) in mice. A total of 120 female ICR mice received MNU solution (1 mg/100 g body wt.) and normal saline at 10 weeks of age into their left and right uterine corpora, respectively. One week later, they were divided into four groups and treated as follows: Group 1 (30 mice) was given 25 ppm E1-containing diet; and Group 2 (30 mice) was fed 5 ppm E2-containing diet; Group 3 (30 mice) was given 25 ppm E3-containing diet; and Group 4 (30 mice) was fed the basal diet alone. At the termination of the experiment (Week 30), all surviving animals were autopsied and histopathological examinations revealed that endometrial adenocarcinomas had developed in all groups. The incidence of adenocarcinomas in the MNU-treated uterine corpus in Group 1 (25 ppm E1-feeding, 9/23, 39%) was significantly higher than that in Group 4 (basal diet, 3/26, 12%, P < 0.05). Also, the incidences of adenocarcinomas in the MNU-treated uterine corpus in Groups 2 (5 ppm E2-feeding, 8/24, 33%) and 3 (25 ppm E3-feeding, 7/26, 28%) were higher than in Group 4, but the difference was not statistically significant. Feeding of diet containing E1, E2 and E3 increased the incidences of the preneoplastic endometrial lesions (atypical, adenomatous or cystic glandular hyperplasia). In the uterine cervix, small numbers of squamous cell carcinomas, dysplasias or hyperplasias were occasionally found in all groups. These results indicate enhancing effects of the above three types of estrogens on the endometrial carcinogenesis induced by MNU in ICR mice.

Adenocarcinoma↗
PubMed1993

Maturation-promoting factor (MPF) is responsible for the transformation of sperm nuclei to metaphase chromosomes in maturing bovine oocytes in vitro.

Bovine oocytes at the germinal vesicle stage were inseminated in Brackett and Oliphant's medium in the presence of BSA (10 mg ml-1), caffeine (5 mmol l-1) and heparin (10 micrograms ml-1). When oocytes were transferred into tissue culture medium (TCM)-199 containing 10% fetal calf serum (FCS) with or without 6-dimethylaminopurine (6-DMAP; 2 mmol l-1) 8 h after insemination and cultured for 15-40 h at 39 degrees C in 5% CO2 in air, 74-83% of oocytes were penetrated and polyspermy (67-80%) was common. At 40 h after culture in 6-DMAP-free medium, 65% and 63% of unpenetrated and penetrated oocytes, respectively, reached metaphase II or beyond. A few (6%) oocytes were activated and contained both male and female pronuclei. Sperm metaphase chromosomes were observed in 90% of the penetrated oocytes. Penetration by more than four spermatozoa greatly retarded the meiotic maturation of the oocyte. However, sperm chromosomes were never observed in oocytes cultured in 6-DMAP supplemented medium and oocyte maturation did not proceed beyond the stage of prometaphase I. These results demonstrate the possible participation of maturation-promoting factor in metaphase chromosome formation in spermatozoa.

Adenine↗
PubMed1993

Effectiveness of in vitro maturation and in vitro fertilization techniques in pigs.

In vitro maturation and in vitro fertilization techniques in pigs have progressed considerably in recent years. Many reports focus on the factors affecting in vitro maturation that lead to normal male pronuclear formation or monospermy after fertilization in vitro. It is suggested that pig follicular fluid (pFF), follicle somatic cells and various hormones are important factors for the maintenance of cytoplasmic maturation of oocytes in vitro, but that fetal calf serum (FCS), which is generally added to maturation medium, is detrimental. A series of experiments clearly indicate that the glutathione (GSH) content of matured oocytes increases greatly when maturation medium is supplemented with cysteine, a precursor of GSH, and the rates of male pronuclear formation increase in parallel with the increasing GSH content. To prevent polyspermy, conditions of maturation and of fertilization in vitro are important. Culture of oocytes in medium with FCS for the first 24 h and with BSA for the second 24 h decreases the incidence of polyspermy, without a significant effect on nuclear maturation. However, it has been shown that secretory macromolecules of the oviduct may reduce the incidence of polyspermy by interacting with fertilizing spermatozoa rather than with oocytes. A reduction of polyspermy by treating spermatozoa with pFF is also reported. In addition to the many improvements in the methodology of in vitro fertilization using unfrozen spermatozoa in pigs, techniques for fertilizing oocytes in vitro with frozen epididymal and ejaculated spermatozoa have also recently been developed.

Animals↗
PubMed1992

Effect of naftidrofuryl oxalate on 5-HT2 receptors in mouse brain: evaluation based on quantitative autoradiography and head-twitch response.

The effects of naftidrofuryl oxalate (LS-121) on 5-HT2 receptors in the brain were assessed in mice on the basis of quantitative autoradiography and head-twitch responses. LS-121 inhibited [3H]ketanserin (2 nM) binding in all brain areas assayed in which there were 5-HT2 receptors, such as the frontal cortex, cingulate cortex, parietal cortex, occipital cortex, temporal cortex, nucleus accumbens, caudate-putamen, olfactory tubercle and hippocampus. In the frontal cortex, which has the highest density of 5-HT2 receptors, the Ki value of LS-121 was 6.08 x 10(-8) M. The inhibitory potencies of methysergide and ritanserin for 5-HT2 receptors were about 16- and 60-fold stronger, respectively, than that of LS-121. Moreover, in behavioral studies, LS-121 (12.5-50 mg/kg i.p.) produced dose-dependent and significant inhibitory effects on head twitches induced by 5-hydroxytryptophan (5-HTP) plus pargyline, which is a 5-HT2 receptor-dependent behavior in mice. These results suggest that LS-121 inhibits 5-HTP plus pargyline-induced head twitches by blocking 5-HT2 receptors.

5-Hydroxytryptophan↗
PubMed1992

Effect of a dihydropyridine analogue, 2-[benzyl(phenyl)amino]ethyl 1,4-dihydro-2,6-dimethyl-5-(5,5-dimethyl-2-oxo- 1,3,2-dioxaphosphorinan-2-yl)-1-(2-morpholinoethyl)-4-(3-nitrophenyl)-3 -pyridinecarboxylate on reversing in vivo resistance of tumor cells to adriamycin.

A newly synthesized dihydropyridine analogue, 2-[benzyl(phenyl)-amino]ethyl 1,4-dihydro-2,6-dimethyl-5-(5,5-dimethyl-2-oxo-1,3,2-dioxaphosphorina n-2-yl)-1- (2-morpholinoethyl)-4-(3-nitrophenyl)-3-pyridinecarboxylate (PAK-200), at 5 microM inhibited the efflux of [3H]vincristine from KB-C2 cells and increased the accumulation of [3H]vincristine in KB-C2 cells to a level similar to that in KB-3-1 cells. PAK-200 inhibited the photoaffinity labeling of P-glycoprotein in KB-C2 membranes by [3H]azidopine. At 5 microM, PAK-200 enhanced the cytotoxic effect of Adriamycin on drug-sensitive KB-3-1 cells, multidrug-resistant KB-8-5 cells, and two human colorectal carcinoma tumor lines, COK-28LN and COK-36LN, by factors of 2, 5, 2, and 3 times, respectively. The calcium antagonistic activity of PAK-200 was about 1000 and 5 times lower than that of another dihydropyridine analogue, nicardipine, and of verapamil, respectively. PAK-200 in combination with Adriamycin completely suppressed the growth of KB-3-1 and COK-36LN and partially suppressed the growth of KB-8-5 but had no significant effect on COK-28LN cells xenografted in nude mice. The level of MDR1 expression of COK-36LN was about 3 times higher than that of COK-28LN, but lower than that of KB-8-5 cells. These results suggest that the interaction of PAK-200 with P-glycoprotein may be partly correlated with the enhancement of the antitumor effect of Adriamycin on xenografted KB-8-5 and COK-36LN cells in nude mice.

Animals↗
PubMed1992

Changes of silver-stained nucleolar organizer regions in mouse endometrial carcinogenesis induced by N-methyl-N-nitrosourea and 17 beta-oestradiol.

A high incidence of endometrial adenocarcinoma and pre-neoplastic lesions was induced in ICR mice treated with N-methyl-N-nitrosourea and 17 beta-oestradiol within 23 weeks. The endometrial lesions were histopathologically similar to those of human subjects. To assess the cell proliferative activity of these lesions, a one-step silver colloid staining for nucleolar organizer regions was applied and the numbers of silver-stained nucleolar organizer regions (AgNORs) were counted. The mean numbers +/- SD of AgNORs in each lesion were as follows: simple hyperplasia, 2.07 +/- 0.36; complex hyperplasia without cytological atypia, 2.79 +/- 0.39; complex hyperplasia with cytological atypia, 3.43 +/- 0.38; and well-differentiated adenocarcinoma, 4.17 +/- 0.40. Significant differences were observed in each lesion (P < 0.001). These findings suggest that the mean numbers of Ag-NORs are increased in the progression of neoplastic changes in the mouse endometrium, as in human endometrial lesions. This rapid induction model of endometrial carcinoma in mice is useful in the understanding of the histogenesis of endometrial carcinoma in human subjects.

Adenocarcinoma↗
PubMed1992

Scattering of the silver-stained proteins of nucleolar organizer regions in Ishikawa cells by actinomycin D.

Scattering of the silver-stained proteins of nucleolar organizer regions (Ag-NOR proteins) was produced by actinomycin D in Ishikawa cells. Scattering of Ag-NOR proteins was found only in cells treated with actinomycin D and various other agents had no effect. Scattering was dose-dependent up to 10(-2) micrograms/ml of actinomycin D, but it was not found at higher concentrations that caused marked inhibition of total DNA and RNA synthesis. Actinomycin D (10(-2) micrograms/ml) caused the following changes: (i) nucleolar segregation and (ii) emergence of dense fibrillar bodies in the nucleoplasm. Ag-NOR proteins were observed on the fibrillar centers and surrounding fibrillar components in control nucleoli, on the fibrillar and amorphous zones in segregated nucleoli, and on the dense fibrillar bodies emerging in the nucleoplasm. The scattering of Ag-NOR proteins was due to the argyrophilic nature of the dense fibrillar bodies. Actinomycin D (10(-1) micrograms/ml) also caused similar morphological alterations in the nucleolus and nucleoplasm, but Ag-NOR proteins were observed only on nucleolar remnants.

Antibiotics, Antineoplastic↗
PubMed1992

Hepatic resection for metastatic squamous cell carcinoma from the uterine cervix.

A solitary hepatic tumor was diagnosed 3.5 years after a 67-year-old woman had undergone radical hysterectomy and postoperative irradiation for stage Ib squamous cell carcinoma of the cervix. Hepatic resection confirmed squamous cell carcinoma that had metastasized from the uterine cervix. One year and 10 months following hepatic resection, this patient is doing well with no evidence of any recurrence. This is a report of successful hepatic resection for metastatic carcinoma from the uterine cervix.

Aged↗
PubMed1992

Fertilization and early cleavage in vitro of ageing bovine oocytes after maturation in culture.

Bovine follicular oocytes cultured for 20 to 48 hours were inseminated with frozen thawed spermatozoa. Significantly higher penetration rates (94 to 100% vs 86 to 94%: P < 0.05) and proportions of polyspermy (35 to 78% vs 22 to 45%: P < 0.01) were obtained for oocytes cultured continuously for 24 hours with spermatozoa than for those separated from spermatozoa 8 hours after insemination. The most prominent effect of ageing of oocytes on early events of penetration was observed in the incidence of polyspermy rather than in the penetration rate and the proportion of pronuclear plus cleaved oocytes: the proportion of polyspermic oocytes significantly increased (P < 0.05) in oocytes inseminated after 28 to 48 hours of culture (36 to 78%) compared with those cultured for 20 to 24 hours (22 to 35%) for maturation. Culture experiments for early development of penetrated oocytes indicated that no significant differences were observed in the proportions of oocytes cleaved to the two- to four-cell stage 48 hours after insemination among those cultured for 20 to 40 hours for maturation. However, further cleavage to the four- to sixteen-cell stage 72 to 96 hours after insemination was greatly inhibited as ageing of oocytes proceeded from 28 hours in culture for maturation.

Journal Article↗
PubMed1992

Toxicity to rats of methanol-fueled engine exhaust inhaled continuously for 28 days.

Fischer 344 rats were exposed to three concentrations of exhaust generated by an M85 methanol-fueled engine (methanol with 15% gasoline) without catalyst for 8 h/d, 7 d/wk for 7, 14, 21, or 28 d. Concentration- and time-dependent yellowing of the fur was prominent in all treated groups. Concentration-dependent increases in the erythrocyte count, hematocrit, hemoglobin concentration, formaldehyde in plasma, and carboxyhemoglobin in the erythrocytes, and decrease in serum alkaline phosphatase activity were seen after all exposure periods. Histopathologically, lesions were found in the nasal cavity and lungs after 7 d of exposure. Squamous metaplasia of the respiratory epithelium of level 1 (level of the posterior edge of the upper incisor teeth) lining of the nasoturbinate and/or maxilloturbinate and infiltration of neutrophils into the submucosa, and decreases of Clara cells in the terminal bronchiolus and of cilia in the bronchiolar epithelium, were observed in the high-concentration group (carbon monoxide, 94 ppm; formaldehyde, 6.9 ppm; methanol, 17.9 ppm; nitrogen oxides, 52.7 ppm; nitrogen dioxide, 10.6 ppm). The histopathological extents of several lesions increased slightly with the exposure time. Slight squamous metaplasia and hyperplasia of the respiratory epithelium at level 1 were also observed in the medium-concentration group (one in three of the high-concentration group). No histopathological changes were found in the olfactory epithelium of the nasal cavity. In the low-concentration group (one in nine of the high-concentration group), no marked histopathological changes in these organs were observed. These results may suggest that the lesions observed in the nasal cavity of rats exposed to methanol-fueled engine exhaust were mainly caused by formaldehyde, although other components in the exhaust also may have affected nasal cavity and/or lungs to less extent.

Alkaline Phosphatase↗