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Biomedical subjects

H Iwasawa

Publications and source records attributed to H Iwasawa.

At least 19 recordsLinked to original sources
PubMed2006

Electronic structure of charge- and spin-controlled Sr(1-(x+y))La(x+y)Ti(1-x)Cr(x)O3.

We present the electronic structure of Sr(1-(x+y))La(x+y)Ti(1-x)Cr(x)O3 investigated by high-resolution photoemission spectroscopy. In the vicinity of the Fermi level, it was found that the electronic structure was composed of a Cr 3d local state with the t(2g)3 configuration and a Ti 3d itinerant state. The energy levels of these Cr and Ti 3d states are well interpreted by the difference of the charge-transfer energy of both ions. The spectral weight of the Cr 3d state is completely proportional to the spin concentration x irrespective of the carrier concentration y, indicating that the spin density can be controlled by x as desired. In contrast, the spectral weight of the Ti 3d state is not proportional to y, depending on the amount of Cr doping.

Journal Article↗
PubMed2004

Improved simultaneous nitrification and denitrification in a single reactor by using two different immobilization carriers with specific oxygen transfer characteristics.

To maximize nitrogen utilization rates during nitrification and denitrification in a simultaneous reaction for direct nitrogen removal from ammonia-nitrogen in a single reactor, two different carriers were applied that immobilized nitrifiers and denitrifiers separately. With the optimized DO concentration and mixing ratio of immobilization carriers, ammonium-nitrogen was successfully removed as designed until the middle phase of treatment where nitrogen removal rate was higher than 83% of the theoretical value, although an imbalance between nitrification and denitrification occurred at a later phase of treatment where residual nitrate-nitrogen concentration was less than 2 mg/l. The new approach using two different carriers to immobilize nitrifiers and denitrifiers separately was proved useful for controlling both nitrification and denitrification rates, enabling the utilization of maximum treatment ability of both nitrifiers and denitrifiers in a single reactor for direct nitrogen removal from ammonium-nitrogen.

Acrylic Resins↗
PubMed2003

Generalized synchronization of chaos in He-Ne lasers.

We experimentally demonstrate synchronization of chaos in one-way coupled He-Ne lasers with optical feedback. We observe different types of synchronization such as identical synchronization, inverse synchronization, and random amplification. These dynamics are maintained only for a short duration of several hundred milliseconds. We also observe generalized synchronization of chaos by using one master and two slave lasers. The generalized synchronization is achieved for a long duration of tens of seconds under injection locking. The generalized synchronization is always maintained while the injection locking is achieved.

Journal Article↗
PubMed2001

[Therapeutic outcome of spasmodic torticollis].

We investigated 117 patients with spasmodic torticollis who had visited us to seek for appropriate treatment in these 14 years. They were 71 men and 46 women, aged 44 +/- 14 (mean +/- SD) years, and suffered from this disorder during 4 +/- 5 years, maximum 26 years. Involuntary abnormal head positions, not only torticollis but also laterocollis and antero- or retrocollis, were contained in this study. Most of them were torticollis due to idiopathic focal dystonia. One or more courses of alcoholization therapy was accomplished in 82 patients who wished to be done. This therapy course consisted of about ten times totally of 99% ethanol injection to the motor point of two most hypertonic neck muscles, either side of the sternocleidomastoideus and the opposite side of the splenius in most cases, repeated every 2 or 3 weeks. One patient received as many as 98 times of this injection and resolved completely. Training to reinforce antagonistic muscles was also instructed. Twenty-one patients (26%) were resolved completely after this treatment. Fifty-four patients (66%) were ameliorated and satisfied partially, but 18 of them relapsed in 1 to 4 years after the treatment and were obliged to repeat one more course of this treatment. On the other hand, in five patients their torticollis improved under certain drug therapy alone. Sixteen patients (14%) gave up to continue the treatment within two months, and 14 patients (12%) dropped out before starting the therapy. This alcoholization therapy resulted in amelioration of torticollis in about 90% of the patients with a long effective period. Nevertheless, this alcohol injection is painful, and requires 5 to 6 months to be completed. In 2 patients who had already received many times of this injection, sudden hoarseness occurred one day immediately after the alcohol injection to the sternocleidomastoideus. This complication was presumably brought about by the unexpected infiltration of alcohol to the laryngeal area, located posterior to that muscle. They recovered in two months, but careful attention should be paid to the adverse effects. If botulinum toxin be available also in our country, we will be able to have another choice of therapy and the treatment of this disorder will become easier.

Adult↗
PubMed2001

[Serial changes in body composition in patients with chronic renal failure on peritoneal dialysis].

Nutritional status is one of the most important factors affecting mortality and morbidity in chronic dialysis patients. There are, however, few data on serial body composition changes in these patients. To investigate serial changes in body composition in patients on peritoneal dialysis, we measured intracellular fluid volume(ICF), extracellular fluid volume(ECF), body protein volume(BPV), body fat volume(BFV) and bone mineral content(BMC) using multifrequency bioelectrical impedance analysis (MF-BIA). MF-BIA was performed in 35 patients, consisting of 21 men and 14 women with a mean age of 51.3 +/- 10.9 years, before and after one year of observation. At the baseline in male patients, ICF was 37.0 +/- 3.4%, ECF 19.7 +/- 1.6%, BPV 20.7 +/- 1.7%, BFV 18.1 +/- 6.6% and BMC 4.5 +/- 0.4% of body weight, and in female patients ICF was 34.4 +/- 2.6%, ECF 17.8 +/- 1.9% BPV 19.0 +/- 1.6%, BFV 24.4 +/- 6.2% and BMC 4.5 +/- 0.4% of body weight. In the group of patients whose body weight increased more than 3 kilograms(n = 9), the increase rate of BFV was 32.3 +/- 20.2%, significantly higher than that of the other segments(p < 0.001). On the other hand, in the group of patients whose body weight decreased more than 3 kilograms(n = 5), each segment showed the same extent of decrease and there was no significant difference in the decrease rates among each segment. In the group of patients whose body weight was stable(n = 21), changes in each body composition segment were extremely small. It could be concluded that the body weight increase is due mainly to increase in BFV and body weight decrease results from a concurrent decrease in each body composition segment in peritoneal dialysis patients.

Adult↗
PubMed2001

[Nerve conduction velocity of repeater F-waves is identical to that of M-waves].

F-wave normally varies in latency and waveform from one response to the next. But the number of identical responses in a series of F-waves may be increased with neurogenic atrophy consistent with a decreased number of motoneurons capable of responding to antidromic stimulation. They are called "repeater F-waves". We herein demonstrate some repeater F-waves observed in three patients with moderate or slight diabetic polyneuropathy. In their motor nerve conduction studies on the peroneal nerve the maximum conduction velocity was 33 m/sec in patient 1, 36 m/sec in patient 2 and 48 m/sec in patient 3. A total of 6 delayed indirect potentials were repeatedly evoked after nerve trunk stimulation. They fulfilled the characteristics of F-wave. Their conduction velocities in the leg segment were 27, 26, 23 m/sec in patient 1, 34, 33 m/sec in patient 2 and 46 m/sec in patient 3. Repeater F-waves are occasionally observed in patients with amyotrophic lateral sclerosis, cervical spondylosis or entrapment neuropathies, in which the number of motoneuron is decreased. In diabetic polyneuropathy some repeater F-waves were also observed in patients not only with moderate to severe neuropathy but also with normal nerve conduction. F-waves are generated by an antidromic backfiring of motor neurons, and they occur preferentially in large motor neurons. Larger motor neurons inhibit smaller axons through the activation of Renshaw cells. In our 3 patients conduction velocities of the repeated F-waves were all identical to the main component of M-wave. These observations reconfirmed the hypothesis that relatively large motor neurons generating F-waves are preferentially activated also in repeater F-waves.

Aged↗
PubMed1999

[Serial change of TL/BMIPP dual SPECT myocardial scintigram in patients with acute myocardial infarction; meaning of chronic mismatch phenomenon].

This study was aimed to elucidate the serial changes and clinical significance of accumulation mismatch with TL and BMIPP dual SPECT myocardial scintigraphy during 6 months in patients with acute myocardial infarction (AMI). The dual SPECT scintigraphy was performed at one, three and six months after onset of AMI in 46 patients who underwent reperfusion therapy. Long axis fractional shortening in infarct-related area and left ventricular end-diastolic volume index (LVEDVI) were measured by left ventriculography performed immediately after reperfusion and at one, six months after onset of AMI. The patients were divided into two groups: those with mismatch (Group (+)) and those without (Group (-)) at one month after reperfusion. Group (+) was subdivided into three groups according to duration of persistence of mismatch; one month persistence (1 M), three months (3 M) and six months (6 M). Improvement of wall motion abnormality (WMA) in infarct-related area was seen at one month after reperfusion in group 1 M and group 3 M, while group 6 M showed no apparent change in WMA throughout the study period. LVEDI did not change at six months after reperfusion in group 1 M and 3 M, while significant increase was seen in group 6 M. It is concluded that the case with disappearance of mismatch between TL and BMIPP until three months after reperfusion indicates myocardial stunning while in the case with long-standing mismatch left ventricular remodeling is suggested.

Adult↗
PubMed1997

[Comparative antimicrobial activity of RP 59,500 (quinupristin-dalfopristin), the first semisynthetic injectable streptgramin, against gram-positive cocci and other recent clinical pathogens].

RP 59,500 (Quinupristin-Dalfopristin) is the first semisynthetic injectable streptogramin antimicrobial agent, which is a combination of quinupristin and dalfopristin in a 30:70 ratio. The components of RP 59,500 act synergically to provide bactericidal activity through action at different sites on bacterial ribosomes. In the present study, the antimicrobial activity of RP 59,500 was compared with those of four macrolides (erythromycin, clarithromycin, azithromycin, roxithromycin). Susceptibility testing was carried out by microdilution method on 303 strains of 10 species, especially antibiotic-resistant Gram-positive cocci. RP 59,500 was active against a wide range of Gram-positive cocci including methicillin-resistant Staphylococci and penicillin-resistant Streptococcus pneumoniae. The MICs90 of RP 59,500 against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis were both 0.25 microgram/ml, although those of four macrolides were higher than 32 micrograms/ml. The MICs90 of RP 59,500 against penicillin-sensitive, -intermediate and -resistant S. pneumoniae were all 0.5 microgram/ml, although those of four macrolides against penicillin-resistant S. pneumoniae were higher than 32 micrograms/ml. RP 59,500 also exhibited equivalent activities to the four macrolides against strains of Streptococcus pyogenes. Streptococcus agalactiae and Moraxella catarrhalis. RP 59,500 exhibited the highest activities against Enterococcus faecalis, Enterococcus faecium and Enterococcus avium strains which are intrinsically resistant to most antimicrobial agents. No cross-resistance was observed between RP 59,500 and the four macrolides, which will merit attention in future clinical trials of the agent. The effect of human serum on the MIC of RP 59,500 was studied with strains of S. aureus, S. epidermidis and E. faecalis. The presence of 20% (V/V) serum had little or no effect on the MIC, although 50% (V/V) serum increased MICs by 4-8 folds. Laboratory-induced resistance to RP 59,500 occurred in a stepwise fashion in broth cultures of S. aureus, S. epidermidis and E. facalis strains and the induction rate was slow and no more than four fold increases were observed. Population analysis was performed on RP 59,500 and the reference macrolides against S. aureus ATCC 25,923 strain. Although low frequencies (less than 0.01%) of resistant sub-population were detected with EM, CAM, AZM and RXM, no RP 59,500-resistant sub-population was detected in this study.

Anti-Bacterial Agents↗
PubMed1996

Two unusual cases of a foreign body in the oral cavity caused by eating raw squid.

Foreign bodies are often encountered by otolaryngologists, but the oral cavity is considered a place where foreign bodies are rare because of its structural and functional features. We here present 2 cases with a foreign body in the oral cavity resulting from eating raw squid. In one of these 2 cases endoscopic examination revealed a gastric foreign body. The foreign bodies in the oral cavity were removed using forceps, together with surrounding mucous membrane. These foreign bodies were identified as sperm bulbs and discharging tube of sogittated calamary (Todarodes pacificus Steenstrup). Larva migrans of anisakiasis are to be differentiated from sperm bulbs; it is important to distinguish between the shape and size of the foreign body in our cases. If sperm bulbs are stuck in the oral cavity, it is necessary to remove them completely to ensure that inflammation is prevented. We stress the importance of checking not only anisakiasis but also sperm bulbs in humans who like eating raw squid.

Animals↗
PubMed1995

The fastest actin-based motor protein from the green algae, Chara, and its distinct mode of interaction with actin.

The endoplasmic streaming in Characean cells is an actin-dependent movement. The motor protein responsible for the streaming was partially purified and characterized. It was soluble at low ionic strength, an ATPase of a molecular mass of 225 kDa and activated more than 100 times by muscle F-actin. Surprisingly, in an in vitro motility assay, the motor protein moved muscle F-actin at 60 microns/s, which is similar to the velocity of streaming in a living cell and 10 times faster than muscle myosin. Proteolytic cleavage of actin impaired movement crucially on muscle myosin, but did not affect movement at all on the Chara motor protein, suggesting that the Chara motor protein would interact with actin via a set of sites different from those of muscle myosin.

Actins↗
PubMed1995

Everninomicin, a new oligosaccharide antibiotic: its antimicrobial activity, post-antibiotic effect and synergistic bactericidal activity.

Antimicrobial activity of everninomicin (SCH) 27899) in comparison with two glycopeptides (vancomycin, teicoplanin) and six beta-lactam agents was evaluated against recent clinical isolates of Gram-positive bacteria. Everninomicin showed the highest activity against the species tested and MICs90% of everninomicin against Streptococcus pneumoniae, Streptococcus pyogenes, Enterococcus faecalis, Enterococcus faecium and Clostridium difficile were 0.1, 0.1, 0.2, 0.39, 0.1 microgram/ml, respectively. MICs90% of everninomicin against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE) were 0.78 microgram/ml. Laboratory induced resistance to everninomicin in strains of S. aureus and E. faecalis occurred in a stepwise manner and at a very slow rate. Post-antibiotic effect against strains of S. aureus and E. faecalis were 1.8 and 2.6 h, respectively, and a little longer than that of vancomycin. Adherence to glass surface of an MRSA strain was strongly repressed by the addition of sub MIC of everninomicin in combination with fosfomycin.

Aminoglycosides↗
PubMed1994

A morphometric analysis of the subcellular distribution of LH beta and FSH beta in secretory granules in the pituitary gonadotrophs of the frog (Rana japonica).

Immunohistochemical localization of lutropin beta (LH beta) and follitropin beta (FSH beta) in the pituitary gland of the frog Rana japonica was studied by the peroxidase-anti-peroxidase method and the two-face, double-labeling method with different-sized gold particles at the light- and electron-microscopic levels, respectively, using monoclonal antibodies against bullfrog LH beta and FSH beta. Light-microscopic immunohistochemistry indicated that approximately 66.0% of all the gonadotrophs in the pituitary contained both LH beta and FSH beta, whereas 33.4% of gonadotrophs contained only LH beta, and 0.6% contained only FSH beta. The staining intensity of LH beta and FSH beta varied from cell to cell. The gonadotrophs were classified into four types (Types I-IV) in terms of their ultrastructural and immunolabeling characteristics. Moreover, several secretory granule types were recognized according to differences in their shape and electron density. In all the cell types, both LH beta and FSH beta were often seen in the same secretory granules, but the proportion of granules bearing both hormones ranged from 5.5% in Type I to 32.7% in Type IV. Most secretory granules in Types I and II were immunolabeled with LH beta alone, whereas a small number of granules were immunolabeled with FSH beta alone. More immunolabeled FSH beta granules were present in Types III and IV than in Types I and II.

Animals↗
PubMed1994

Tissue-targeting ability of saccharide-poly(L-lysine) conjugates.

To evaluate the effect of introducing a saccharide moiety to poly(amino acids) on tissue distribution, several glycoconjugates of epsilon-(2-methoxyethoxyacetyl)-poly(L-lysine) of three molecular weights were synthesized using an octylene spacer between the sugar and polymer chain. Methoxyethoxyacetylation of the epsilon-amino group of the lysine unit in poly(L-lysine) was useful for avoiding nonspecific distribution to many tissues as the result of cationic charges. The tissue-targeting ability of each saccharide moiety was considered as the actual amount changed in each tissue caused by saccharide modification. Galactose terminated saccharides such as galactose, lactose and N-acetylgalactosamine accumulated exclusively in the liver, probably by the hepatic receptor. These conjugates could therefore be good carriers for a drug delivery system to the liver. On the other hand, the mannosyl and fucosyl conjugates were preferentially delivered to the reticuloendothelial systems such as those in the liver, spleen and bone marrow. In particular, fucosyl conjugates accumulated more in the bone marrow than in the spleen. Xylosyl conjugates accumulated mostly in the liver and lung. Generally, the accumulated amount in the target tissue increased with increasing molecular weight and an increased number of saccharides on one molecule of polymer.

Animals↗
PubMed1993

Seasonal changes in plasma concentrations of sex steroids in the salamander Hynobius nigrescens.

Changes in plasma concentrations of androgens, estradiol-17 beta, and progesterone were examined throughout the year in Hynobius nigrescens. The highest mean concentration of androgens (312.7 ng/ml) was found in males in the process of spermiation and having just entered the breeding pond in early spring. Plasma estradiol-17 beta concentration was at its base level in females both before and after the animals had entered the pond. Plasma progesterone concentrations were low throughout the year except during the aquatic phase in March when females possessed some ova within the coelom and many ova in the oviducts and ovisacs after the completion of ovulation. During the terrestrial phase, or nonbreeding season, plasma concentrations of androgens and estradiol-17 beta were in approximate correspondence with the development of sex accessory structures. This is the first documentation of plasma concentrations of sex steroids in hynobiid salamanders.

Animals↗
PubMed1993

17 alpha,20 alpha-Dihydroxy-4-pregnen-3-one is the naturally occurring spermiation-inducing hormone in the testis of a frog, Rana nigromaculata.

Spermiation, the process in which vertebrate spermatozoa are detached from investing Sertoli cells into the lumen of the seminiferous tubule, is a prerequisite for the successful fertilization. Using an in vitro Rana nigromaculata spermiation bioassay, we have shown that gonadotropin initiates spermiation by inducing the synthesis of delta 4-steroids by testis fragments. Among all of the delta 4-steroid metabolites produced by R. nigromaculata testis fragments, spermiation-inducing activity was confined to only one metabolite; this metabolite was identified as 17 alpha,20 alpha-dihydroxy-4-pregnen-3-one (17 alpha,20 alpha-DP). Induction of spermiation by gonadotropin in vitro was accompanied by marked elevations in 17 alpha,20 alpha-DP concentrations in incubation media. These findings provide evidence that 17 alpha,20 alpha-DP is the nautrally occurring spermiation-inducing hormone in R. nigromaculata.

17-alpha-Hydroxyprogesterone↗
PubMed1993

[Antimicrobial activity of clarithromycin and its effect on bacterial adherence to medical material].

Antimicrobial activity of clarithromycin (CAM) in comparison with other 6 macrolides was determined against 419 recent clinical isolates including Streptococci, Enterococci, Staphylococci, Moraxella, Haemophilus and Bacteroides strains. MICs80's of CAM against Streptococcus pneumoniae, Streptococcus pyogenes and Streptococcus agalactiae were 0.78, 0.10 and 0.10 microgram/ml, respectively. MICs80's against Moraxella catarrhalis and Haemophilus influenzae were 0.05 and 1.56 micrograms/ml, respectively. Laboratory-induced resistance to CAM in strains of S. pneumoniae, Enterococcus faecalis or methicillin-sensitive Staphylococcus epidermidis occurred in stepwise fashion and at a very low rate. Adherence to silicon filter of strains of Pseudomonas aeruginosa or S. epidermidis was strongly repressed by the addition of sub-MIC of CAM or other macrolides. Although tosufloxacin (TFLX) alone had no bactericidal activity against the sessile cells of P. aeruginosa strains tested, TFLX showed synergistic bactericidal activity when combined with sub-MICs of CAM or erythromycin.

Bacterial Adhesion↗
PubMed1992

Synthesis of omega-(methoxycarbonyl)alkyl and 9-(methoxycarbonyl)-3,6-dioxanonyl glycopyranosides for the preparation of carbohydrate-protein conjugates.

omega-(Methoxycarbonyl)alkyl glycopyranosides of D-mannose having C4, C7, C9, C12, and C15 carbon chains, L-fucose and 2-acetamido-2-deoxy-D-mannose having C7 and C9 carbon chains, D-xylose and 2-acetamido-2-deoxy-L-fucose having a C9 carbon chain, and 9-(methoxycarbonyl)-3,6-dioxanonyl glycopyranosides of D-mannose, 2-acetamido-2-deoxy-D-mannose, and L-fucose were synthesized as intermediates for coupling to human serum albumin in order to examine the effect of chain length and hydrophobicity of the spacer arm on the binding specificity of lectins. 8-(Methoxycarbonyl)octyl glycosides of beta-D-Man-(1----2)-alpha-D-Man, alpha-D-Man-(1----2)-alpha-D-Man, alpha-D-ManNAc-(1----2)-alpha-D-Man, beta-D-GlcNAc-(1----2)-alpha-D-Man, and their 6-O-positional isomers, beta-D-Man-(1----6)-alpha-D-Man, alpha-D-Man-(1----6)-alpha-D-Man, alpha-D-ManNAc-(1----6)-alpha-D-Man, and beta-D-GlcNAc-(1----6)-alpha-D-Man, were also synthesized.

Carbohydrate Sequence↗