Biomedical subjects
Publications and source records attributed to N Ozawa.
A rare case of tentorial schwannoma in a 29-year-old male is described. The schwannoma was located within the leaves of the tentorium. MRI showed a wedge-shaped enhancing tumour. Exact nerve of origin of the tumour could not be identified. We speculate that the tumour arose from the tentorial branch of the trigeminal nerve. The literature concerning intracranial schwannoma unrelated to a major cranial nerve is reviewed.
Nosocomial transmission of hepatitis C virus (HCV) subtype 1b involving 11 haemodialysis patients occurred in a haemodialysis unit in Japan in March 2000. Sequencing of the HCV-E1 region (411-bp) and phylogenetic-tree analysis showed near identity between HCV isolates derived from these patients and a haemodialysis patient who was known to be HCV-positive. The mode of transmission could not be conclusively established, but retrospective analysis suggested that the sharing of contaminated multidose vials of heparin-saline solutions, which were prepared in the Haemodialysis Center using accidentally contaminated instruments such as needles, may have been responsible for the outbreak. To prevent transmission of HCV in a haemodialysis unit, it may be important to observe strictly standard precautions and to prepare all medications in the Pharmacy. After these measures were taken, no new seroconversions and no new nosocomial transmissions of HCV have been observed in our haemodialysis unit.
1. Linezolid (ZYVOX), the first of a new class of antibiotics, the oxazolidinones, is approved for treatment of Gram-positive bacterial infections. 2. The aim was to determine the absorption, distribution, metabolism and excretion (ADME) of linezolid in mouse, rat and dog in support of preclinical safety studies and clinical development. 3. Conventional replicate study designs were employed in animal experiments, and biofluids were assayed by HPLC or HPLC-MS. 4. Linezolid was rapidly absorbed after p.o. dosing with an p.o. bioavailability of > 95% in rat and dog, and > 70% in mouse. Twenty-eight-day i.v./p.o. toxicokinetic studies in rat (20-200mg kg(-1) day(-1)) and dog (10-80 mg kg(-1) day(-1)) revealed neither a meaningful increase in clearance nor accumulation upon multiple dosing. 5. Linezolid had limited protein binding (<35%) and was very well distributed to most extravascular sites, with a volume of distribution at steady-state (V(ss)) approximately equal to total body water. 6. Linezolid circulated mainly as parent drug and was excreted mainly as parent drug and two inactive carboxylic acids, PNU-142586 and PNU-142300. Minor secondary metabolites were also characterized. In all species, the clearance rate was determined by metabolism. 7. Radioactivity recovery was essentially complete within 24-48 h. Renal excretion of parent drug and metabolites was a major elimination route. Parent drug underwent renal tubular reabsorption, significantly slowing parent drug excretion and allowing a slow metabolic process to become rate-limiting in overall clearance. 8. It is concluded that ADME data were relatively consistent across species and supported the rat and dog as the principal non-clinical safety species.
Crystal structures of(Ba1-xLax)2In2O5+x (x=0.00, 0.20, 0.30, 0.40, 0.50) were analyzed by EXAFS and the powder X-ray Rietveld method. A Fourier transform of In K-edge EXAFS data from (Ba1-xLax)2In2O5+x showed a peak between 1.2 and 2.0 A attributed to the nearest oxide ions around In3+ cation. The peak as back-Fourier transformed, and the structural parameters were refined by the least square fitting. The coordination number of In3+ cation increases with increasing La3+ cation) content. This means oxygen is introduced at interstitial site by keeping an electroneutrality. As a result of the oxygen distribution, the oxide ion vacancies distribute randomly. The electrical conductivities of (Ba1-xLax)2In2O5 rapidly increased above 1203 K due to the order-disorder transition of oxygen vacancy. On the other hand, the electrical conductivities of (Ba1-xLax)2In2O5+x (x=0.20, 0.30, 0.35. 0.40, 0.45, 0.50) did not show the sharp discontinuity in the conductivity because the disorder phase of defective perovskite type structure was stabilized by doping La3+ cations at A-site even at low temperature.
1. Bropirimine (2-amino-5-bromo-6-phenyl-4-pyrimidinone) is a member of a class of antineoplastic agents that are administered concomitantly or sequentially with anticancer 5-fluorouracil (5-FU) prodrugs in clinical patients. Interactions between bropirimine and 5-fluorouracil (5-FU) were investigated on dihydropyrimidine dehydrogenase (DPD) activity, the rate-limiting enzyme of 5-FU metabolism, in human liver cytosol. Apparent DPD activity was determined by measuring the recovery of [14C]5-FU by HPLC. 2. The apparent activity of 5-FU metabolism (2.1-100 microM) showed a linear relationship in the Eadie-Hofstee plot in the pooled cytosol, suggesting that a single enzyme is responsible for apparent 5-FU metabolism. Km and Vmax were estimated to be 23 microM and 0.32 nmol min(-1) mg(-1) protein, respectively. Apparent DPD activity for 5-FU (25 microM) in the cytosol from 12 individual donors ranged from 0.017 to 0.39 (0.16 +/- 0.12) nmol min(-1) mg(-1) protein, indicating a large intersubject variance. 3. The suicidal inactivators of the DPD enzyme, (E)-5-(2-bromovinyl)uracil and 5-bromouracil (6.3-50 microM), illustrated concentration-dependent inhibition on DPD activity. Isocytosine (6.3-100 microM), used as a negative control, did not affect DPD activity. Bropirimine (6.3-100 microM) also did not show any inhibition of DPD activity. Therefore, bropirimine is unlikely to cause increases in 5-FU levels in clinical patients after co-administration of bropirimine with 5-FU prodrugs.
PROBLEM: There is no reliable laboratory test available to diagnose immunologically mediated miscarriages. We investigated the clinical significance of maternal anti-paternal leukocyte antibodies by flow cytometry after alloimmunization. METHOD OF STUDY: The flow cytometry crossmatch (FCXM) was performed in 158 patients with a history of three or more unexplained first-trimester miscarriages without live birth. After negative FCXM patients were immunized, subsequent pregnancy outcomes and FCXM results were followed. RESULTS: Of 112 subsequent pregnancies, 83 of 100 (83.0%) FCXM-positive patients after immunotherapy had successful pregnancy outcomes, whereas seven of 10 (70.0%) FCXM-negative patients had miscarriages (P = 0.0001). The percent live birth ratio was 2.77 (CI, 1.07-7.16; P=0.0001) for FCXM-positive patients compared to FCXM-negative patients. The calculated predictive value showed that 75.6% of FCXM-negative patients would have subsequent miscarriages. CONCLUSIONS: Positive FCXM is closely associated with successful pregnancy outcome following immunotherapy. We propose that FCXM might be included in the routine laboratory tests for the management of recurrent miscarriages.
A 76-year-old female patient underwent papillary muscle reconstruction, and d-CABGs a month after the onset of myocardial infarction. Posterior papillary muscle (PPM) was recognized to be ruptured partially, its stump was sewn to original PPM. An ePTFE suture (CV 5) was placed from anterior mitral leaflet to anterior papillary muscle in attempt to reinforce PPM-repair. Carpentier-Edwards ring was inserted and d-CABGs (LITA to LAD and GEA to RCA) were performed, simultaneously. Postoperative examination revealed no regurgitation and no stenosis of bypass grafts during follow-up period of 5 months after the procedure. Papillary muscle reconstruction was effective procedure for MR due to the ruptured papillary muscle.
Concentrations of cholesterol 7alpha- and 7beta-hydroperoxides (Ch 7-OOHs) in the skin of rats were determined by HPLC with a chemiluminescence detector. We demonstrated that (a) the concentrations of Ch 7-OOHs in rat skin were highly correlated with rat age (r = 0.929; N = 51, 1 to 55 weeks old), (b) the concentrations of Ch 7-OOHs in the skin of rats in an ambient light room were not significantly different from those found in rats kept in a dark room for 12 weeks, and (c) lipid peroxidation in vitro induced by ADP-Fe2+ caused an increase in the concentrations of Ch 7-OOHs in homogenates of rat skin. These results indicated that levels of Ch 7-OOHs in skin might be a good marker for aging of rats and might be independent of housing illumination, thus a good marker for endogenous lipid peroxidation. Furthermore, we observed that ultraviolet light B (UVB) irradiation markedly enhanced the concentrations of Ch 7-OOHs in the skin of rats in vivo depending on the duration of the irradiation, and the increases in Ch 7-OOHs were inhibited by radical scavengers, i.e. tocopherols. Therefore, it was suggested that the levels of Ch 7-OOHs in the skin could also be a good marker for UVB-dependent lipid peroxidation.
An HPLC-UV method was developed for assay of linezolid in dog, rat, mouse, and rabbit plasma. Linezolid and the internal standard were extracted on a solid phase cartridge (SPE) and separated on a reversed-phase column (C8, 4.6x150 mm, 5 microm) with 20% acetonitrile in water as mobile phase. The SPE quantitatively recovered linezolid and the internal standard from plasma samples. The chromatographic peak height ratio or peak area ratio based on UV absorbency at 251 nm was used for quantitative analysis. The assay procedures were simple and the assay was specific and had adequate precision and accuracy. Calibration standards with concentrations over the range of 0.01 20 microg/ml were validated for routine sample analysis to support the pharmacokinetic and toxicology studies with linezolid in dog, rat, mouse, and rabbit. Analysis of quality control samples showed the coefficients of variation were usually <10% and the measured and theoretical concentrations differed by <10% in most assays. Linezolid in the plasma samples was stable when stored at below -20 degrees C for at least 63 days, at room temperature (22-23 degrees C) for up to 24 h, and after three freeze-thaw cycles. This HPLC method has been successfully used in multiple laboratories to assay plasma samples from pharmacokinetic and toxicology studies with linezolid in the animal species.
Free and ester forms of cholesterol 7alpha- and 7beta-hydroperoxides (Ch 7-OOHs) in skin lipids of humans were separated and determined by high performance liquid chromatography with a chemiluminescence detector. We first demonstrated the presence of Ch 7-OOHs in lipids of human skin. The levels of Ch 7-OOHs found in skin lipids of healthy Japanese volunteers (n = 5) ranged from 2.78 to 25.2 pmol/cm2 skin, indicating large inter-individual differences. However, the intra-individual differences of Ch 7-OOHs levels in skin lipids between right and left arms were less than 25% (-16.4% to 24.0%). Inter-day differences of Ch 7-OOHs in 5 subjects at 1 week interval were also small (-36.7% to 47.7%). Additionally, we investigated effects of sunlight exposure on the levels of Ch 7-OOHs in skin lipids of healthy Japanese volunteers (n = 24). The levels of Ch 7-OOHs in skin lipids significantly increased from 10.0+/-6.7 to 38.9+/-38.0 pmol/cm2 skin by sunlight exposure (10-40 mJ/cm2/min) for 3 h. Therefore, natural sunlight exposure causes lipid peroxidation in skin lipids of humans. These results suggest that the level of Ch 7-OOHs is a good marker for lipid peroxidation in human skin.
We identified singlet oxygen adduct of cholesterol, 3beta-hydroxy-5alpha-cholest-6-ene-5-hydroperoxide (5alpha-OOH), in skin of rats pretreated with oral doses of pheophorbide a and subsequent visible irradiation, that have been known to induce photosensitive diseases in animals and humans. In a living animal body, this is the first demonstration of presence of 5alpha-OOH, that is known to be formed exclusively by reaction in vitro between singlet oxygen and cholesterol. By the quantitative determination with high performance liquid chromatography equipped with a chemiluminescence detector, we observed time-dependent increase in concentrations of 5alpha-OOH in skin of rats pretreated with oral doses of pheophorbide a and subsequent visible irradiation, suggesting the occurrence of a labile activated oxygen species, singlet oxygen, in this system.
An assay method for determination of cholesterol 5alpha-, 7alpha-, and 7beta-hydroperoxides (ChOOHs) in rat skin using high-performance liquid chromatography (HPLC) with a chemiluminescence detector has been developed. In the assay method, free form and free plus ester forms of ChOOHs could be separately determined by HPLC in combination with the treatment of a tissue extract by cholesterol esterase. Lower limits of quantitation for cholesterol 5alpha-, 7alpha-, and 7beta-hydroperoxides were 0.2, 0.1, and 0.5 nmol/g skin, respectively. This assay method showed that (i) good absolute recoveries of ChOOHs from rat skin (80-90% of radiolabeled ChOOHs added to rat skin); (ii) negligible autoxidation of cholesterol caused by the assay procedure (<9.4x10(-5)% of radiolabeled cholesterol added to rat skin); and (iii) good correlation between ChOOHs added to rat skin and ChOOHs determined, indicating this assay method is applicable to quantify ChOOHs in rat skin. By using this assay method, we observed that (i) cholesterol 5alpha-hydroperoxide was detected in skin of rats pretreated with oral doses of pheophorbide a and subsequent visible irradiation; (ii) concentrations of cholesterol 7-hydroperoxides in skin of rats in an ambient light room were not significantly different from those in a dark room for 12 weeks; and (iii) ultraviolet light B irradiation markedly enhanced the concentrations of cholesterol 7-hydroperoxides in the skin of rats.
S-Warfarin 7-hydroxylation, S-flurbiprofen 4'-hydroxylation, and diclofenac 4'-hydroxylation activities were determined in liver microsomes of 30 humans of which 19 were wild-type (Arg144.Ile359), 8 were heterozygous Cys (Cys144.Ile359), and 3 were heterozygous Leu (Arg144.Leu359) allelic variants of the cytochrome P450 2C9 (CYP2C9) gene. All of the human samples examined contained P450 protein(s) immunoreactive with anti-CYP2C9 antibodies in liver microsomes. Individuals with the Cys144 allele of CYP2C9 had similar, but slightly lower, activities for the oxidations of these substrates than those of wild-type CYP2C9. One of the three human samples heterozygous for the Leu359 allele had very low Vmax and high Km values for the oxidation of three substrates examined, while the other two individuals gave kinetic parameters comparable to those seen in the wild-type and Cys144 CYP2C9. Reverse transcriptase-polymerase chain reaction analysis, however, showed that all of the three human samples with the heterozygous Leu359 variant were found to express both Ile359 and Leu359 variants at relatively similar extents in liver RNA of three humans. These results suggest that the Cys144 variant of CYP2C9 catalyzes the CYP2C9 substrates at rates comparative to, but slightly lower than, those of wild-type CYP2C9, while the Leu359-allelic variant has slower rates for the oxidation of these drug substrates. Activities for the oxidation of these CYP2C9 substrates in humans with heterozygous Leu359 allele is likely to be dependent on the levels of expression of each of the wild- and Leu-variants in the livers. However, one of the humans with a heterozygous Leu allele was found to have very low activities towards the oxidation of CYP2C9 substrates. The basis of this defect in catalytic functions towards CYP2C9 substrates is unknown.
Monoamine-related electrochemical signal was measured by in vivo chronoamperometry at a sampling rate of 5 Hz with a Nafion-coated carbon fiber placed in the caudate nucleus of the rat (n=5) performing an auditory reaction-time task. During the task, the rat pressed a lever in response to a tone stimulus to get food reward. An averaging technique was employed to extract event-related changes in monoamine concentration with respect to the tone stimulus, lever pressing or feeding. It was found that the oxidation current increased phasically for several seconds following the tone presentation with the mean onset latency being 0.4+/-0.2 s. Lever pressing was preceded by the onset of increase in two rats. Prominent increase was not observed following the tone presentation during the resting state, passive feeding, and lever pressing unrelated to the task. The results indicate that phasic increase in monoamine concentration occurs at the caudate nucleus in response to conditioned auditory stimulation in the reaction-time task. This response is not simply the consequence of sensory stimulation, motor reaction, or feeding, but is possibly influenced by integrative processes. The present electrochemical findings are consistent with the previous electrophysiological data on dopamine neuronal activity. However, pharmacological researches will be necessary in order to determine the substance involved in the phasic response.
Dermal 7alpha- and 7beta-hydroperoxycholest-5-en-3beta-ols (cholesterol 7alpha- and 7beta-hydroperoxides), regarded as good aging markers in the rat (Ozawa, N., Yamazaki, S., Chiba, K., Aoyama, H., Tomisawa, H., Tateishi, M., and Watabe, T. (1991) Biochem. Biophys. Res. Commun. 178, 242-247), were reduced in the presence of glutathione (GSH) with concomitant formation of GSSG by cytosol from rat liver in which no detectable level of the hydroperoxides had been demonstrated to occur. The GSH peroxidase (GSH Px) activity toward the toxic steroid hydroperoxides was exerted to almost the same extent by both Alpha-class GSH S-transferases (GSTs), Ya-Ya and Ya-Yc, and by selenium-containing GSH Px (Se-GSH Px) in rat liver cytosol. None of three Mu-class GSTs, Yb1-Yb1, Yb1-Yb2, and Yb2-Yb2, and a Theta-class GST, Yrs-Yrs, from rat liver and a Pi-class GST, Yp-Yp, from rat kidney showed any appreciable GSH Px activity toward the hydroperoxides. The subunit Ya-bearing GSTs and Se-GSH Px purified from rat liver cytosol showed marked differences in apparent specific activity toward the cholesterol hydroperoxides (GSTs Ya-Ya > Ya-Yc >> Se-GSH Px). However, a kinetic study indicated that Se-GSH Px had a higher affinity for steroid hydroperoxides than did the GSTs, so that Se-GSH Px could catalyze the reduction of lower concentrations of cholesterol 7-hydroperoxides with approximately equal Vmax/Km values to those by the GSTs. Rat skin had no GST bearing the subunit Ya but contained only a very low concentration of Se-GSH Px, possibly resulting in the accumulation of cholesterol 7-hydroperoxides in the skin but not in the liver. From rat skin cytosol, GSTs Yc-Yc, Yb1-Yb1, Yb1-Yb2, Yb2-Yb2, and Yp-Yp were isolated, purified to homogeneity, and identified with the corresponding GSTs from liver and kidney. The GSTs accounted for 0.23% of total skin cytosolic protein, and the most abundant isoform of skin GSTs was Yb2-Yb2, followed by Yc-Yc, Yp-Yp, Yb1-Yb1, and Yb1-Yb2 in decreasing order.
The relation of the hippocampal neuronal activity to the rat event-related potential (ERP) generation was examined during an auditory discrimination oddball paradigm. ERPs were recorded using a linearly-arranged series of electrodes chronically implanted at the skull, in the frontoparietal cortex, in the CA1 and CA3 regions of the dorsal hippocampus and in the thalamus. The target tone elicited N40, P100, N200, and P450 at the skull electrode. The non-target tone, on the other hand, prominently evoked only the P100 component. At the intracranial electrodes, the ERP amplitude at the latency of the skull P450 was significantly greater in the CA3 region than that at other recording sites, although a phase reversal was not observed. The results indicate that the P450 of the rat may correspond to the human P3, and that the neuronal activity in the hippocampus is involved in its generation.
Between January 1985 and March 1996, 522 women with submucous myomas underwent resectoscopic myomectomy. Fifty-two were treated with subsequent endometrial ablation. To ensure easy and complete resection of sessile or large submucous myomata, the two-resectoscope method was used. To increase safety, the procedure was monitored by simultaneous ultrasound, and in 1995 Lin's myoma forceps was produced to facilitate the procedure. The average specimen weight was 23.9 g (505 patients). The largest intrauterine myoma was 148 g and the largest myoma delivery was 210 g. The average operating time was 34.2 minutes (517 patients). No uterine perforation occurred. No laparotomy was necessary during or after the operation. Almost all of the women experienced improvement of their symptoms.