Biomedical subjects

M Ishikawa

Publications and source records attributed to M Ishikawa.

At least 91 records · Page 5Linked to original sources

PubMed2001

Effects of supplementation with free radical scavengers on the survival and fertilization rates of mouse cryopreserved oocytes.

BACKGROUND: This study was conducted to investigate the effects of supplementation with free radical scavengers on the survival and fertilization rates of freeze-thawed mouse oocytes. METHODS: Superovulated oocytes with cumulus cells were cryopreserved by slow freezing in propanediol combined with a rapid thawing protocol. The cryopreservation medium was supplemented with the antioxidant enzymes superoxide dismutase (SOD) and catalase, and with the nitric oxide (NO) scavenger, haemoglobin (Hb). RESULTS: The addition of 50 IU/ml SOD showed significantly higher survival and fertilization capabilities compared with control (P < 0.01). Oocyte survival was greatly increased by concomitant addition of SOD with 10 IU/ml catalase (P < 0.01). On the other hand, the NO donor (sodium nitroprusside) inhibited survival and fertilization rates (P < 0.05). Significantly decreased survival and fertilization rates were also observed following the addition of high concentrations (10(-3) to 10(-6) nmol/l) of the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). In contrast, significantly better oocyte survival and fertilization rates were detected with low concentrations (10(-7) nmol/l) of L-NAME. Oocyte survival potential was significantly increased by addition of Hb (1 microg/ml, P < 0.05). Moreover, oocyte survival and fertilization rates were significantly promoted by the concomitant addition of SOD with Hb (P < 0.01). CONCLUSIONS: These results suggest that supplementation of free radical scavengers, particularly combinations of SOD with NO scavengers in freezing and thawing media, improved the post-thaw survival and fertilization rates of cryopreserved mouse oocytes.

Animals↗

PubMed2001

How is the liver primed or sensitized for alcoholic liver disease?

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Hidekazu Tsukamoto and Yoshiyuki Takei. The presentations were (1) Tribute to Professor Rajendar K. Chawla, by Craig J. McClain; (2) Dysregulated TNF signaling in alcoholic liver disease, by Craig J. McClain, S. Joshi-Barve, D. Hill, J Schmidt, I. Deaciuc, and S. Barve; (3) The role of mitochondria in ethanol-mediated sensitization of the liver, by Anna Colell, Carmen Garcia-Ruiz, Neil Kaplowitz, and Jose C. Fernandez-Checa; (4) A peroxisome proliferator (bezafibrate) can prevent superoxide anion release into hepatic sinusoid after acute ethanol administration, by Hirokazu Yokoyama, Yukishige Okamura, Yuji Nakamura, and Hiromasa Ishii; (5) S-adenosylmethionine affects tumor necrosis factor-alpha gene expression in macrophages, by Rajendar K. Chawla, S. Barve, S. Joshi-Barve, W. Watson, W. Nelson, and C. McClain; (6) Iron, retinoic acid and hepatic macrophage TNFalpha gene expression in ALD, by Hidekazu Tsukamoto, Min Lin, Mitsuru Ohata, and Kenta Motomura; and (7) Role of Kupffer cells and gut-derived endotoxin in alcoholic liver injury, by N. Enomoto, K. Ikejima, T. Kitamura, H. Oide, Y. Takei, M. Hirose, B. U. Bradford, C. A. Rivera, H. Kono, S. Peter, S. Yamashina, A. Konno, M. Ishikawa, H. Shimizu, N. Sato, and R. Thurman.

Animals↗

PubMed2001

Silent period in the mentalis muscle induced by facial nerve and cutaneous stimulation.

The aim of this study was to demonstrate that silent periods of the mentalis muscle are induced after facial nerve stimulation and cutaneous stimulation in normal subjects. When the marginal mandibular branch of the facial nerve and the cutaneous nerve in areas adjacent to the lower lip were stimulated during slight voluntary contraction of the mentalis muscle, silent periods were elicited with surface electrodes on the mentalis muscle. The early phase and the late phase of the silent period were elicited by marginal mandibular branch stimulation. The early phase of the silent period was recognized following the F waves and it disappeared at 36.3 msec. The average duration of the late phase of the silent period was 59.2 msec, with an average latency of 62.5 msec. Only the late phase of the silent period after cutaneous stimulation could be elicited, with a duration and latency of 55.9 msec and 54.0 msec respectively. The authors conclude that the silent period is able to be elicited in the mentalis muscle by peripheral nerve stimulation, and is one of the late responses in facial muscles.

Adult↗

PubMed2001

Delayed resolution of residual hemifacial spasm after microvascular decompression operations.

OBJECTIVE: After microvascular decompression to treat hemifacial spasm (HFS), resolution of the HFS is often gradual. We carefully investigated the course of the gradual resolution of HFS and examined the differences between patients with and without postoperative HFS. METHODS: One hundred seventy-five patients with HFS were monitored, for observation of 1) whether postoperative HFS occurred, 2) when it occurred, and 3) when it disappeared after microvascular decompression. For two groups of patients, with (Group I) and without (Group II) postoperative HFS, we investigated age, sex, spasm side, preoperative facial nerve block (botulinum toxin treatment), decompression material, preoperative HFS period, offender (compressing vessel), temporary and permanent postoperative complications, and electromyographic findings. RESULTS: In Group I (88 patients), postoperative HFS began within 4 days after surgery, a period that we have termed the silent period of postoperative HFS; the median value for the time to resolution was 28 days. The other 87 patients exhibited no postoperative HFS (Group II). There was a significantly higher incidence of postoperative facial weakness in Group II (Group II, 41.3%; Group I, 25.5%; P = 0.02 by logistic regression analysis). In Group I, there was no statistically significant relationship between the investigated parameters and the silent period or the postoperative HFS period, as determined by Cox proportional-hazards regression analysis, except for the number of preoperative facial nerve blocks. Electromyographic investigation of F waves revealed facial paresis during the silent period in a patient. CONCLUSION: Approximately 50% of patients with HFS exhibited residual spasm postoperatively. An immediate postoperative silent period of 4 days without spasm was characteristic. One-quarter, one-half, and 90% of the residual spasm resolved by 1 week, 1 month, and 8 months after surgery, respectively.

Adult↗

PubMed2001

Catalytic center of an archaeal type 2 ribonuclease H as revealed by X-ray crystallographic and mutational analyses.

The catalytic center of an archaeal Type 2 RNase H has been identified by a combination of X-ray crystallographic and mutational analyses. The crystal structure of the Type 2 RNase H from Thermococcus kodakaraensis KOD1 has revealed that the N-terminal major domain adopts the RNase H fold, despite the poor sequence similarity to the Type 1 RNase H. Mutational analyses showed that the catalytic reaction requires four acidic residues, which are well conserved in the Type 1 RNase H and the members of the polynucleotidyl transferase family. Thus, the Type 1 and Type 2 RNases H seem to share a common catalytic mechanism, except for the requirement of histidine as a general base in the former enzyme. Combined with the results from deletion mutant analyses, the structure suggests that the C-terminal domain of the Type 2 RNase H is involved in the interaction with the DNA/RNA hybrid.

Archaea↗

PubMed2001

New fabrication system for dental implant surgical stents: time-saving laboratory technique using a light-curing resin and transparent artificial teeth.

BACKGROUND: Surgical stents are a prerequisite for dental implant diagnosis. However, the traditional fabrication method including wax-up, investment, and resin polymerization is time consuming. PURPOSE: This article introduces a new fabrication system using a light-curing resin and transparent artificial teeth to reduce time spent in the laboratory. MATERIALS AND METHOD: The process of this system includes placing the light-curing resin and the artificial teeth on the partially edentulous dentition and alveolar ridge, making an appropriate pattern for the stent, light-curing for 5 minutes, briefly polishing, and making holes for titanium guide pins. RESULTS: This system requires only 30 to 40 minutes in the laboratory to complete a stent after mounting the casts on the articulator. Owing to the elasticity of the light-curing resin, this system eliminates the need for a blockout procedure on the undercuts of existing teeth on the casts, protects the casts from breakage, and provides the appropriate retention intraorally without any retainers. As well, titanium guide pins embedded in the stent were clearly identified by panoramic and computed tomographies. CONCLUSIONS: The new fabrication system proposed here can be time saving and, further, serve benefits for radiographic diagnosis.

Dental Implantation, Endosseous↗

PubMed2001

Mutation of host delta9 fatty acid desaturase inhibits brome mosaic virus RNA replication between template recognition and RNA synthesis.

All positive-strand RNA viruses assemble their RNA replication complexes on intracellular membranes. Brome mosaic virus (BMV) replicates its RNA in endoplasmic reticulum (ER)-associated complexes in plant cells and the yeast Saccharomyces cerevisiae. BMV encodes RNA replication factors 1a, with domains implicated in RNA capping and helicase functions, and 2a, with a central polymerase-like domain. Factor 1a interacts independently with the ER membrane, viral RNA templates, and factor 2a to form RNA replication complexes on the perinuclear ER. We show that BMV RNA replication is severely inhibited by a mutation in OLE1, an essential yeast chromosomal gene encoding delta9 fatty acid desaturase, an integral ER membrane protein and the first enzyme in unsaturated fatty acid synthesis. OLE1 deletion and medium supplementation show that BMV RNA replication requires unsaturated fatty acids, not the Ole1 protein, and that viral RNA replication is much more sensitive than yeast growth to reduced unsaturated fatty acid levels. In ole1 mutant yeast, 1a still becomes membrane associated, recruits 2a to the membrane, and recognizes and stabilizes viral RNA templates normally. However, RNA replication is blocked prior to initiation of negative-strand RNA synthesis. The results show that viral RNA synthesis is highly sensitive to lipid composition and suggest that proper membrane fluidity or plasticity is essential for an early step in RNA replication. The strong unsaturated fatty acid dependence also demonstrates that modulating fatty acid balance can be an effective antiviral strategy.

Blotting, Northern↗

PubMed2001

Potent and long-lasting action of lafutidine on the human histamine H(2) receptor.

BACKGROUND/AIM: Based on animal models, lafutidine, a novel histamine H(2) receptor (H(2)R) antagonist, is reported to show potent and long-lasting antagonisms of histamine H(2)R-mediated effects. However, no reports have been published concerning its direct interaction with the human H(2)R. This study aims at characterizing its interaction with human H(2)R. METHODS: Chinese hamster ovary cell lines stably expressing human H(2)Rs were obtained. The dose-dependent effects of lafutidine and famotidine on [(3)H]tiotidine binding and histamine-stimulated cAMP production were analyzed. The effects of preincubation with 2.78 x 10(-7) M of lafutidine or famotidine for 30 min on histamine-dependent cAMP production and [(3)H]tiotidine binding were also examined after 0, 1, 2, 4, and 12 h. This concentration is below the C(max) of lafutidine (10 mg p.o.) and above the C(max) of famotidine (20 mg p.o.). RESULTS: Lafutidine inhibited [(3)H]tiotidine binding and histamine-stimulated cAMP production as or more potently than famotidine. At higher concentrations lafutidine was more potent than famotidine. In addition, preincubation with 2.78 x 10(-7) M lafutidine, but not with 10(-5) M famotidine, had marked inhibitory effects which persisted as long as after extensive washing. CONCLUSION: Lafutidine shows a potent and long-lasting antagonism on the human H(2)R.

Acetamides↗

PubMed2001

Inhibitory effect of modified 5'-capped short RNA fragments on influenza virus RNA polymerase gene expression.

We have shown previously that the 5'-capped short phosphodiester RNA fragments, Cap decoy, (Gm 12 nt) are potent inhibitors of influenza virus RNA polymerase gene expression. Here we investigate the modified capped RNA derivative containing phosphorothioate oligonucleotides (Cap decoy) as a potential influenza virus RNA polymerase inhibitor. The modified 5'-capped short phosphorothioate RNA fragments (Gms 12-15 nt) with the 5'-capped structure (m7GpppGm) were synthesized by T7 RNA polymerase. The 5'-capped short RNA fragments (Gms 12-15 nt) were encapsulated in liposome particulates and tested for their inhibitory effects on influenza virus RNA polymerase gene expression in the clone 76 cells. The 12-15 nt long Gms RNA fragments showed highly inhibitory effects. By contrast, the inhibitory effects of the 13 nt long short RNA fragments (Gm 13 nt) were considerably less in comparison with the 5'-capped short phosphorothioate RNA fragments (Gms 12-15 nt). In particular, the various Gms RNA chain lengths showed no significant differences in the inhibition of influenza virus RNA polymerase gene expression. Furthermore, the capped RNA with a phosphorothioate backbone was resistant to nuclease activity. These phosphorothioate RNA fragments exhibited higher inhibitory activity than the 5'-capped short RNA fragments (Gm 12 nt). These decoys may prove to be useful in anti-influenza virus therapeutics.

Animals↗

PubMed2001

Removal of anterior clinoid process for basilar tip aneurysm: clinical and cadaveric analysis.

The difficulty in the operation for basilar tip aneurysm is the restriction in surgical working space. To resolve this problem, aggressive skull base surgery has been reported, but these techniques are not prevalent. Pterional and subtemporal approaches are commonly used for basilar tip aneurysms. In an attempt to increase the surgical working space during the pterional approach, the anterior clinoid process and the roof of the optic nerve were removed extradurally to increase the mobilization of the intracranial internal carotid artery and optic nerve. The effects of removing the anterior clinoid process and microanatomy in the perioptic area were analyzed by cadaveric procedures in 10 cases (20 sides). With this procedure, the internal carotid artery can be retracted medially with a spatula 6.1 +/- 0.8 mm (mean +/- SD). The length and the area of dural fold in the bone defect region in the optic canal roof are 2.1 mm and 13.6 mm. In 10 clinical cases, this procedure allowed enough space to approach the basilar tip aneurysm without disturbing the internal carotid artery blood flow. The clinical outcome was satisfactory.

Basilar Artery↗

PubMed2001

Method to improve cosmetic outcome following craniotomy.

This technical note describes a simple method for reducing the dead space created by craniotome due to the loss of bone dust and improving the cosmetic outcome following a craniotomy. After drilling the burr holes for the craniotomy, the bone between the holes is drilled away in a standard fashion except that multiple regions of about 1 cm in length are left intact. These intact regions are broken using a periosteal elevator and fixed like a bridge when the bone is replaced. The resulting bone flap is readily returned to its original position without making the dead space created by regular craniotomy. The amount of the dead space caused by losing the bone dust is reduced and a good cosmetic recovery is obtained. This technique is useful for both craniotomy and facial bone surgery, which requires cosmetic results.

Bone and Bones↗

PubMed2001

Circumvention of acquired resistance to doxorubicin in K562 human leukemia cells by oxatomide.

We studied the effect of oxatomide, an antiallergic drug, on the resistance of K562 cells to doxorubicin. Oxatomide synergistically potentiated the cytotoxicity of doxorubicin in doxorubicin-resistant K562 cells (K562/DXR) at a concentration of 1-10 microM, but had hardly any synergistic effect on the parental cell line (K562) at the same concentration. Oxatomide inhibit P-glycoprotein pump-efflux activity and the binding of [3H]-azidopine to the cell-surface protein P-glycoprotein, in a dose-related manner. These results indicate that oxatomide reverses the multidrug-resistance phenotype through direct interaction with P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

Reversal of vinblastine resistance in human leukemic cells by haloperidol and dihydrohaloperidol.

Haloperidol, an antipsychotic, was investigated in cells overexpressing P-glycoprotein to detemine whether it was a clinically effective drug to reverse for reversing multidrug resistance (MDR) mediated by P-glycoprotein. A nontoxic concentration of haloperidol (1-30 microM) enhanced the cytotoxic effects of vinblastine (VBL) concentration-dependently in VBL-resistant human leukemia (K562/VBL) cells, but had no effect in the parent cells. Haloperidol also enhanced the cytotoxicities of epirubicin, doxorubicin and actinomycin D in the K562/VBL cells, but not those of idarubicin or cisplatin; this enhancement was less than that of the VBL toxicity in the VBL-resistant tumor line. Haloperidol increased the intracellular accumulation of VBL in the K562/VBL cells, and the binding of [3H]-azidopine to the cell-surface protein, P-glycoprotein, was inhibited by haloperidol in a concentration-dependent manner. Haloperidol was less potent than verapamil. Thus, haloperidol appeared to potentiate anticancer agents through the reversal of MDR by competitively inhibiting drug-binding to P-glycoprotein. In contrast, the main metabolite of haloperidol, dihydrohaloperidol, without antipsychotic activity, had less of an effect. Therefore, haloperidol might be useful in reversing drug-resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

Optimization technique for a Prompt Gamma-ray SPECT collimator system.

Because background radiation in an irradiation room creates a problem with the PG-SPECT (Prompt Gamma-ray Single Photon Emission Computed Tomography) system, which evaluates the absorbed dose for the Boron Neutron Capture Therapy treatment, optimization of a collimator system was performed while taking the shielding of background gamma-rays into consideration. Assuming that a parallel-beam collimator is used, three parameters--the diameter of a hole, the length of the collimator, and the number of detectors (the number of holes of the collimator)--were selected for optimization. Because the combinations of these parameters are limitless, it is difficult to determine them simultaneously. Therefore, a statistically derived Optimization Criterion has been proposed to optimize these parameters. When the spatial resolution was 1 cm-FWHM (full width at half maximum), the optimal diameter of the collimator was 5.4 mm, the optimal length was 321 mm, and the optimal number of detectors was 31 x 31.

Boron Neutron Capture Therapy↗

PubMed2001

Directional distribution of radiation around an accident at a uranium fuel factory in Tokai-mura, 1999.

A beta-ray survey was carried out on concrete walls of the boundary and buildings after a criticality accident at a factory of JCO Co. Ltd. at Tokai-mura. A remarkable distribution of beta counts was observed on the walls depending on the complex internal and external structures of buildings surrounding a precipitation vessel containing uranium 23 days after the accident. The directional distribution function, based on the beta counts on the walls, was consistent with data concerning the neutron dose rate measured in several directions during the accident, suggesting an anisotropic neutron distribution to the residential area.

Humans↗

PubMed2001

Cytokinin-induced gene expression in cultured green cells of Nicotiana tabacum identified by fluorescent differential display.

The cell growth and plastid development of cultured green tobacco cells were maintained by the phytohormone cytokinin. After subculture into cytokinin-free medium, when cytokinin treatment was resumed, physiological changes induced by cytokinin were analyzed. Changes in chlorophyll biosynthesis and photosynthetic gene expression were observed 1 week after cytokinin induction, and changes in cell growth were observed 2 weeks after cytokinin induction. Two cytokinin-induced genes (cig) were isolated from these cells using the fluorescent differential display technique. Northern analysis confirmed that expression of these cig was induced by both natural and synthetic cytokinins. The expression of cig1 was also induced by abscisic acid, and its cDNA sequence was similar to the proline dehydrogenase gene. The expression of cig2 is specific to cytokinin and is not induced by other phytohormones. The amino acid sequence encoded by cig2 is similar to the GDP/GTP exchange factor eIF2B, which regulates translation initiation. The expression of these cig suggests a complex induction system involving cytokinin and other phytohormones.

Amino Acid Sequence↗

PubMed2001

Association of angiotensinogen gene polymorphism with erythropoietin-induced hypertension: a preliminary report.

The association of the angiotensinogen (AGT) gene variation at codon 235, the T235 variant, with hypertension induced by erythropoietin (Epo) was investigated in patients with progressive renal disease requiring treatment for renal anemia with Epo. The subjects for the study were patients with renal diseases with serum creatinine concentration exceeding 2 mg/dl and a hematocrit (Ht) of less than 30%. During the run-in period, blood pressure was well controlled with an appropriate salt restricted diet and/or antihypertensive treatment. The patients were then given 6,000 IU of Epo once a week until the Ht rose by 5%. For the overall patient group, AGT gene polymorphism analysis revealed T235T (T/T) in 31 cases (61%), M235T (M/T) in 19 cases (37%), and M235M (M/M) in 1 case (2%). In response to treatment with Epo, hypertension (defined as an increase in mean blood pressure greater than 10 mmHg) was found in 11 cases (22%), all of who carried the homozygous T allele (T/T). On the other hand, the frequency of T/T in patients who did not develop hypertension was 50% (T/T:T/M=20:19 cases), indicating a significant difference (p=0.003 by Chi-square). Variables estimated to be associated with Epo-induced hypertension were the T allele, gender (male), and the degree of increase in Ht, in descending order. Our preliminary research indicates that individuals who carry two copies of the T allele, i.e., who are homozygous for T, are highly susceptible to development of hypertension when subjected to Epo. These results suggest that the AGT T235 variant may be the primary gene responsible for the development of Epo-induced hypertension.

Adult↗

PubMed2001

Metabolic effects of 20 kDa and 22 kDa human growth hormones on adult male spontaneous dwarf rats.

BACKGROUND: Two molecular forms of human GH (hGH) have been shown to be biologically active. The 20 kDa form has been reported to have weaker diabetogenic and lipolytic actions than the 22 kDa form. OBJECTIVE: To analyze the carbohydrate metabolism of 20 kDa and 22 kDa hGH, using the adult male spontaneous dwarf rat (SDR), which is GH deficient. DESIGN: SDRs were given 20 kDa or 22 kDa hGH in doses of 125 microg/rat or 500 microg/rat, or saline, for 10 days, and their weight, serum IGF-I, glucose, insulin, leptin and body composition were measured. RESULTS: Weight and serum IGF-I increased both in the 20 kDa and 22 kDa groups, but IGF-I concentrations were significantly lower in the 20 kDa group than in the 22 kDa group. Serum glucose was not increased by either 20 kDa or 22 kDa hGH, whereas insulin was significantly increased after the higher dose of the 22 kDa hGH. Although blood concentrations of leptin were decreased by both 20 kDa and 22 kDa hGH, values were lower in the high-dose 20 kDa group than in the group given the same dose of 22 kDa hGH. Both forms of GH increased the percentage body water and body protein content, and decreased the percentage of body fat by the same degree. The observation that the higher dose of the 22 kDa hGH increased insulin concentrations without changing blood glucose demonstrates that this concentration of the hormone induces insulin resistance, whereas the same dose of 20 kDa hGH does not. CONCLUSIONS: The results can be interpreted to indicate that the higher dose of the 22 kDa hGH has diabetogenic activity, as reported previously, whereas the 20 kDa hGH has lower diabetogenic activity. The 20 kDa form of hGH may therefore be more useful in treating adult GH deficiency, especially those with severe obesity.

Animals↗