Biomedical subjects

Y Yoshimura

Publications and source records attributed to Y Yoshimura.

At least 415 records · Page 23Linked to original sources

PubMed1990

Squamous cell carcinoma-antigen for detection of squamous cell and mucoepidermoid carcinoma after primary treatment: a preliminary report.

This study evaluated the efficacy of using the periodic measurement of the serum level of squamous cell carcinoma antigen (SCC-antigen) for determining the local recurrence and/or metastasis of squamous cell and mucoepidermoid carcinomas after primary treatment. It was found that at the time of clinical recognition of recurrence, the SCC-antigen level was normal, but metastasis to regional lymph nodes or to remote organs generally was accompanied by an increase of SCC-antigen. Changes in the SCC-antigen level with mucoepidermoid carcinoma seemed to be less sensitive than with squamous cell carcinoma.

Aged↗

PubMed1990

Desmoplastic variant of ameloblastoma: report of a case and review of the literature.

A case of desmoplastic variant of ameloblastoma is reported. The lesion, in a 36-year-old Japanese woman, was successfully treated by partial maxillectomy. Reconstruction was carried out with a block of hydroxyapatite about 7 years and 6 months later. Six cases, including our case, reported up to the present are summarized and reviewed.

Adult↗

PubMed1990

Secondary correction of bilateral cleft lip nose deformity.

For correction of the bilateral cleft lip nasal deformity, a modified bilateral reverse U incision is used in combination with a short, forked flap; by using this combination, satisfactory lengthening of the columella, preserving the natural pout of the lip, can be obtained. We have applied this method to 12 cases undergoing secondary repair of bilateral cleft lip in the past 3 years, and the results of this treatment, along with representative photographs of some of our patients, are presented herein.

Adolescent↗

PubMed1990

An instrument for harvesting the outer table of the skull.

An angled oscillating saw devised for in situ harvesting of the outer table of the skull is presented. With its tip toward the outer table, this saw runs less risk of injuring the inner table and entering the cranial cavity. We have experienced no complication due to the harvesting of the outer table using this instrument.

Bone Transplantation↗

PubMed1990

Effects of gonadotropin-releasing hormone agonists on meiotic maturation of follicle-enclosed oocytes in rabbits.

The effects of GnRH agonists on in vitro maturation of rabbit follicle-enclosed oocytes were studied. Rabbit preovulatory follicles were cultured with or without hCG (10(2) ng/ml), buserelin (10(2)-10(5) ng/ml), or leuprolide (10(2)-10(5) ng/ml) for 14 hours in vitro. GnRH agonists induced the resumption of meiosis in the follicle-enclosed oocytes in a dose-dependent manner. The percentage of oocytes achieving GVBD following treatment with 10(5) ng/ml buserelin (87.9 +/- 6.3%) or 10(5) ng/ml leuprolide (86.0 +/- 4.1%) did not differ significantly from hCG-treated control (87.3 +/- 3.8%). Mature oocytes initially were detected within 2 hours of GnRH agonist exposure. Concomitant addition of a GnRH antagonist at 10(4) ng/ml significantly blocked the stimulatory effect of GnRH agonist on oocyte maturation. GnRH agonists significantly stimulated both prostaglandin (PG) E2 (PGE2) and PGF2 alpha production by preovulatory follicles (p less than 0.01), but secreted prostanoid levels did not differ significantly among different concentrations of GnRH agonists. Meiotic maturation of follicle-enclosed oocytes following GnRH agonist exposure began 2 hours earlier than production of PGs. PG production stimulated by GnRH agonists was reduced significantly by indomethacin. However, oocyte maturity in the presence of GnRH agonist plus indomethacin did not differ significantly from that of GnRH agonist alone. GnRH agonistic analogues induce the resumption of meiosis in follicle-enclosed oocytes in rabbits by a mechanism other than PG stimulation.

Animals↗

PubMed1990

Long-term depression but not potentiation is induced in Ca(2+)-chelated visual cortex neurons.

An entry of Ca2+ into postsynaptic sites may play a role in the induction of long-term potentiation (LTP) of synaptic transmission in the visual cortex. To test this hypothesis, a Ca(2+)-chelator was injected into layer II/III neurons of sliced visual cortex obtained from young rats, and excitatory postsynaptic potentials (EPSPs) of these cells to test stimulation of the white matter were observed before and after tetanic stimulation of the same site. To confirm the effectiveness of the tetanus, field potentials reflecting the activities of many cells were recorded with another extracellular electrode. The chelator injection led to long-term depression (LTD) of EPSPs following tetanic stimuli which simultaneously induced LTP of field potentials derived from unchelated cells in most of the slices tested. This suggests that a low concentration of post-synaptic, free Ca2+, when associated with tetanic inputs, may lead to LTD while a rise of Ca2+ may lead to LTP.

Animals↗

PubMed1990

Augmentation of the nostril splint for retaining the corrected contour of the cleft lip nose.

Whatever method is used to correct the deformity of the cleft lip nose, it is important to maintain the corrected contour of the nose for a certain period postoperatively. For this purpose, moldable silicone rubber is used to add volume to a ready-made nostril splint. With this material it is easy to make a splint that fits the individual contour of the nostril. Clinical examples are presented.

Adult↗

PubMed1990

Tracheoplasty with palatal mucoperiosteal graft.

A case of tracheal reconstruction with a palatal mucoperiosteal graft is reported. The patient is a 75-year-old woman who had the anterior wall of her trachea resected for invading thyroid carcinoma. Palatal mucoperiosteum, which is easy to handle, provided both the lining and supporting tissue for the trachea. Local neck skin was used for covering. This procedure proved very successful.

Aged↗

PubMed1990

Induction of ovulation with pulsatile subcutaneous administration of human menopausal gonadotropin in patients with polycystic ovary syndrome.

The present study was undertaken to determine whether ovulation can be induced in patients with polycystic ovary syndrome (PCOS) by pulsatile subcutaneous administration of hMG after the pituitary secretion of LH and FSH was suppressed with a gonadotropin releasing hormone (GnRH) analogue. The results of the combined regimen cycles (group II) were compared with those of hMG (group I) or FSH (group III) pulsatile administration in the same PCOS patients. The ovulation rate (89.1% of 46 cycles) in group I was significantly greater (p less than 0.01) than that found in group II (65.9% of 41 cycles). In group III, ovulation occurred in 89.5% of the 19 treatment cycles. Ovarian hyperstimulation syndrome (OHSS) occurred in 28.3% of cycles in group I, 7.3% in group II, and 26.3% in group III, respectively. The incidence of OHSS in group II was significantly lower than that found in group I or III. The rates of pregnancy were 10.9% of cycles in group I, 4.9% in group II, and 21.1% in group III, respectively. All 10 fetuses were singleton conceptions, and the pregnancies continued successfully to term. The present data demonstrate that pulsatile subcutaneous administration of hMG or FSH is effective in the induction of successful ovulation and the establishment of singleton pregnancy in patients with PCOS.

Adult↗

PubMed1990

Prolactin inhibits plasminogen activator activity in the preovulatory follicles.

The present study was designed to determine the effects of PRL on changes in morphology and plasminogen activator (PA) activity in the preovulatory follicles. Rabbit ovaries were perfused with hCG alone or with hCG plus at 10, 10(2), or 10(3) ng/ml. PRL at 10(3) ng/ml directly inhibited the degeneration and decomposition of surface epithelial cells induced by hCG exposure. The subsurface connective tissue was visualized by treatment with sodium dodecyl sulfate, which removed surface epithelial cells from the ovary, thereby exposing collagen fibrils and the basal lamina. Sodium dodecyl sulfate treatment revealed inhibition of connective tissue disruption at the apex of the follicle wall in PRL-treated ovaries. PA activity in mature follicles in perfused rabbit ovaries exposed to hCG increased from 1.40 +/- 0.08 to 28.4 +/- 4.25 IU/g tissue after 4 h of perfusion. The addition of PRL to the perfusate inhibited the hCG-stimulated increase in intrafollicular PA activity in a dose-dependent fashion. Although at 7 h mature follicles treated by hCG alone showed greater intrafollicular PA activity than those treated with hCG plus PRL, this difference was not significant. These results suggest that PRL may act directly by interfering with mechanical events within the ovary that are required for the rupture of mature Graafian follicles, probably via the inhibition of intrafollicular tissue PA activity.

Animals↗

PubMed1990

The effects of lipoxygenase products on progesterone and prostaglandin production by human corpora lutea.

The present study was undertaken to assess the effects of the products of the lipoxygenase pathway on steroidogenesis and the production of prostaglandins (PGs) by human corpora lutea in the midluteal phase. In the first experiment luteal cells were cultured with 5-hydroxyeicosatetraenoic acid (5-HETE) at 10, 100, 500, or 1000 ng/mL in the presence or absence of hCG at 100 ng/mL for 10 days. The addition of 5-HETE dose-dependently inhibited progesterone (P) production by the cultural luteal cells. P production stimulated by exposure to hCG was also reduced significantly in response to 5-HETE. However, 5-HETE had no effect on the production of 6-keto-PGF1 alpha, PGF2 alpha, or PGE2 by cultured luteal cells at any point during the culture period. In the second experiment the reaction products of soybean lipoxidase of arachidonic acid (AA-LIP) were added to cultured luteal cells. Treatment with either AA or LIP alone had no effect on basal P production. The addition of AA-LIP at all concentrations tested reduced P production by cultured luteal cells in the presence or absence of hCG. AA-LIP significantly reduced basal 6-keto-PGF1 alpha secretion in cultured luteal cells on day 2. Although the stimulatory effect of AA on luteal PGE2 production was maintained throughout the entire culture period, the lipoxygenase products of AA did not affect AA-stimulated PGE2 production by cultured luteal cell. These results suggest that the products of the lipoxygenase pathway may be important in the involution of human corpora lutea.

Adult↗

PubMed1990

The effect of the follicular fluid adenosine 3',5'-monophosphate degradation rate on successful fertilization and cleavage of human oocytes.

Follicular fluid (FF) and oocytes were obtained from 19 women for in vitro fertilization. Ovulation was induced with clomiphene citrate and human menopausal gonadotropin. Thirty-seven FF samples containing mature oocyte-corona-cumulus complexes were used to measure steroids, gonadotropins, and cAMP. The FF specimens were divided into three groups: follicles yielding ova that were fertilized and cleaved (group A), follicles containing fertilized ova without further cleavage (group B), and follicles containing nonfertilized oocytes (group C). The FF levels of progesterone, 17 beta-estradiol, LH/hCG, and FSH did not differ significantly among the groups. Mean FF cAMP concentrations declined from 17.5 +/- 2.5 pmol/mL 15 min after follicle aspiration to 3.6 +/- 0.9 pmol/mL after 3 h. The initial FF cAMP concentration did not differ significantly among three groups. However, the cAMP degradation rate in group A (119 +/- 13 X 10(-4) pmol/min) was significantly greater than that in group B (62 +/- 10 X 10(-4) pmol/min) or group C (75 +/- 8 X 10(-4) pmol/min). In conclusion, an increased intrafollicular cAMP degradation rate was associated with successful fertilization and cleavage of human oocytes in vitro. These data suggest that the degradation rate of FF cAMP may be a marker of optimal follicular development and oocyte maturation.

Adult↗

PubMed1990

Allopurinol protects pancreatic beta cells from the cytotoxic effect of streptozotocin: in vitro study.

Isolated rat pancreatic beta cells in monolayer culture were shown to be protected from the cytotoxic effect of streptozotocin (STZ) by allopurinol. Pretreatment with allopurinol for 2 h caused dose-dependent inhibition of the decreased secretion of insulin by the cells induced by STZ (2 mM, for 1 h), 500 microM allopurinol causing complete inhibition of this effect of STZ. Pretreatment with allopurinol (250 microM) also prevented the rapid decrease in intracellular adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide concentrations in beta cells induced by treatment with STZ. High performance liquid chromatography revealed that the intracellular concentration of uric acid in STZ-treated cells was about 3 fold that of control cells. This finding suggests that the reaction of xanthine oxidase is facilitated in the cells exposed to STZ probably due to an increased supply of substrate resulting from decrease in intracellular ATP. Based on these results, a possible mechanism of the effect of allopurinol on the cytotoxic effect of STZ via xanthine oxidase is discussed.

Adenosine Triphosphate↗

PubMed1990

Direct evidence for the presence of methylmercury bound in the thyroid and other organs obtained from mice given methylmercury; differentiation of free and bound methylmercuries in biological materials determined by volatility of methylmercury.

Peroxidase in mouse thyroid was inhibited by mercuric chloride but not by methylmercury in in vivo and in vitro systems (Nishida, et al., J. Histochem. Cytochem., 37, 723 (1989)). To identify the reason for the difference, the present study was conducted to examine whether methylmercury is indeed bound within cells or tissues. Mice were given radioactive methylmercury by intubation for 18 d and the tissues were dissected out and vacuum-dried. With this procedure, free methylmercury was evaporated off and the bound mercury remained. The thyroid, liver, kidney and fats examined showed no loss of radioactivity under the vacuum, indicating that the mercury was bound to the thyroid, as well as the other tissues. Radioactive mercuric chloride was nonvolatile regardless of the presence or absence of the tissues. The preferential affinity of methylmercury for SH-containing materials was re-confirmed by this method.

Animals↗

PubMed1990

Effect of 2,4-dihydro-3H-1,2,4-triazole-3-thiones and thiosemicarbazones on iodide uptake by the mouse thyroid: the relationship between their structure and anti-thyroid activity.

Antithyroid activity of 2,4-dihydro-3H-1,2,4-triazole-3-thiones and thiosemicarbazones was tested by measuring the uptake ratio of thyroid: serum (T/S) of 125I through the mouse thyroid. Substitution with an alkyl group at the 5-position of the triazole nucleus remarkably increased the activity but substitution at the N-2 and/or N-4 positions caused a significant decrease in the activity, indicating the necessity of unsubstituted thioureylene moiety for the antithyroid activity. Thiosemicarbazone derivatives which are an open ring structure of triazoles showed comparable antithyroid activities to those in a ring form, but one thiosemicarbazone showed a much higher toxicity than the corresponding ring form compound. This suggests that the ring structure is not essential for the activity but is necessary to reduce toxic effect. Of fourteen compounds tested, 5-methyl-2,4-dihydro-3H-1,2,4-triazole-3-thione was the most potent antithyroid compound with low toxicity, with a potency tenfold that of propylthiouracil, a drug currently used.

Animals↗

PubMed1990

Importance of the concentration of ATP in rat pancreatic beta cells in the mechanism of streptozotocin-induced cytotoxicity.

The effects of streptozotocin (STZ) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on monolayer cultures of rat pancreatic beta cells were compared. The intracellular NAD concentration was markedly decreased by both 2 mmol STZ/l and 13.6 mumol MNNG/l, but insulin secretion was decreased significantly only by STZ. The intracellular ATP level decreased rapidly and in a time-dependent manner with STZ, but decreased less on treatment with MNNG: 80% decrease with STZ but only 35% decrease with MNNG in 12 h in the cells exposed to the chemicals for 1 h and then washed thoroughly. STZ decreased oxygen consumption of rat liver mitochondria in a time- and dose-dependent manner and enhanced the generation of hydroxyl radicals (DMPO-adducts). This enhancement was doubled on the addition of succinate as a substrate. Mitochondrial ATP production was also decreased significantly by STZ, but not by MNNG. Thus the marked depletion of intracellular ATP in beta cells by STZ seems to be due mainly to a direct effect on mitochondrial production. From these results, we suggest that the cytotoxic effect of STZ in pancreatic beta cells is due to a reduction in the intracellular level of ATP, rather than of NAD.

Adenosine Triphosphate↗

PubMed1990

Isolation, characterization and structures of PA-46101 A and B.

New antibiotics, PA-46101 A and B, were isolated from the culture broth of a Streptomycete. The molecular formulae of A and B were determined to be C52H70O18 and C61H86O22, respectively, by elemental analyses, NMR and mass spectrometry. Their structures were elucidated by X-ray crystallography and NMR spectroscopy. These antibiotics are active in vitro against anaerobic Gram-positive and Gram-negative bacteria and also against a limited number of aerobic Gram-positive bacteria.

Aminoglycosides↗

PubMed1990

Structure of di-O-alpha-maltosyl cyclodextrins produced from alpha-maltosylfluoride and cyclodextrins.

The structures of di-O-alpha-maltosyl beta-cyclodextrins ((G2)2-beta-CDs), which were produced from alpha-maltosylfluoride (alpha-G2F) and cyclodextrin (CD) by the transfer action of debranching enzymes, were examined by the enzymic method using Bacillus subtilis saccharifying alpha-amylase (BSA). (G2)2-beta-CD was converted to (G1)2-beta-CD by treatment with glucoamylase before the examination. BSA completely hydrolyzed (G1)2-beta-CD to produce glucose, 6(3)-O-alpha-glucosylmaltotriose, and 6(3),6(5)-di-O-alpha-glucosyl maltopentaose. (G2)2-beta-CD was the mixture of 6A,6C-di-O-alpha-maltosyl beta-CD and 6A,6D-di-O-alpha-maltosyl beta-CD. The ratio of A,C/A,D in (G2)2-beta-CD synthesized with Pseudomonas isoamylase and Aerobacter pullulanase were 40:60-45:55 and 30:70, respectively. The content of 6A,6C-di-O-alpha-maltosyl gamma-CD in (G2)2-gamma-CD synthesized by isoamylase was about 35%.

Bacillus subtilis↗