Search PubMedSearch

Biomedical subjects

Y Iizuka

Publications and source records attributed to Y Iizuka.

At least 19 recordsLinked to original sources

Multiple cerebral arteriovenous shunts in children: report of 13 cases.

The authors present a series of 13 multiple arteriovenous malformations (MAVMs) in the pediatric population (16.9% of their overall series of brain AVMs in this group). Two types of MAVMs can be distinguished: congenital and acquired. Congenital MAVMs may be of the nidus or fistula type. They may be uni- or bilateral, placed in one or several cerebral lobes, separated or close one to another, or even systematized (Wiburn-Mason syndrome). The symptoms created by these MAVMs are the same as those encountered in the presence of other AVMs, with hemorrhage as revealing symptom in 31% of patients. The responsibility of one particular nidus in the onset of clinical signs is often difficult to determine. From an angioarchitectural point of view, it seems that venous drainage changes are mainly responsible for the symptomatology. The natural history of these MAVMs is difficult to assess; spontaneous regression has been noted in 15% of cases. Acquired cerebral MAVMs can be due to angiogenesis ("sprouting" or "non-sprouting") around a true AVM because of previous hemorrhage or ischemia, or to pial shunts associated with dural arteriovenous malformations. The treatment of MAVMs is difficult. Embolization seems to the authors the best therapeutic modality available, as surgery or radiosurgery are often unable to treat these multifocal lesions. Anatomical cure is rarely obtained; the therapeutic strategy has to be targeted on the symptomatic lesions.

Adolescent

The monocyte tumor necrosis factor-alpha production in patients with acute leukemia in complete remission.

Tumor necrosis factor-alpha (TNF-alpha) production by unstimulated and lipopolysaccharide (LPS)-stimulated peripheral monocytes has been studied in 17 acute myeloid leukemia (AML) patients, 54 AML patients in complete remission (AML-CR), 9 acute lymphoblastic leukemia (ALL) patients and 13 ALL patients in complete remission (ALL-CR). TNF-alpha production by the unstimulated monocytes in ALL patients (n = 6, mean: 6.6 +/- 4.9 u/ml) was higher than that of normal controls (n = 13, 0.9 +/- 0.7 u/ml), AML patients (n = 14, 2.0 +/- 2.1 u/ml) and AML-CR patients (n = 21, 1.4 +/- 1.2 u/ml). TNF-alpha production by the LPS-stimulated monocytes of the AML-CR patients (n = 54, 12.4 +/- 13.4 u/ml) was significantly higher than that of the normal controls (n = 21, 3.5 +/- 2.5 u/ml) and the AML patients (n = 17, 2.6 +/- 2.4 u/ml), p < 0.01, but there were not any significant differences among the AML-CR patients and the ALL patients or the ALL-CR patients. We separated the AML-CR patients into 3 groups, depending on the length of their remission, and found that AML-CR patients with longer than 6 months (M) but less than 60 M (n = 21, 15.7 +/- 16.9 u/ml) and the patients with a remission longer than 60 M (n = 11, 18.2 +/- 15.9 u/ml) had significantly higher TNF-alpha production than that of the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease

Serum soluble CD4, CD8 and IL-2R levels in adult acute myeloid leukemia in remission.

We have measured the serum levels of soluble CD4, CD8 and IL-2R in 43 patients with AML in complete remission (AML-CR). The sCD8 levels of AML-CR patients (443.9 +/- 224.4 u/ml) were significantly high as compared to that of the normal controls (177.1 +/- 76.3 u/ml), p < 0.01. The sIL-2R levels of AML-CR patients were 715.0 +/- 646.3 u/ml, which significantly differed when compared to 322.1 +/- 65.7 u/ml for the normal controls, p < 0.01. However, the sCD4 levels of AML-CR patients were 9.6 +/- 4.7 u/ml, which did not differ from the 8.3 +/- 2.6 u/ml of the normal controls. The AML-CR patients showed significantly increased sCD8 and sIL-2R levels at all ranges during the remission from one to 188 months. The sCD8 levels and sIL-2R levels of the AML-CR patients showed a close correlation, p < 0.01. Further, the sCD8 levels and lymphokine activated killer cell cytotoxic activity showed a close correlation, p < 0.05. The presence of the activation of anti-tumor immunity may be related to the continuance of the remission in the AML-CR patients.

Adolescent

Effect of rat CINC/gro, a member of the interleukin-8 family, on leukocytes in microcirculation of the rat mesentery.

Rat cytokine-induced neutrophil chemoattractant (CINC) is a member of the IL-8 family, and its human counterpart is gro/MGSA but not IL-8. We ascertained that chemically synthesized CINC was comparable to native CINC/gro with regard to chemotactic activity for rat neutrophils and studied the effect of synthesized CINC/gro on circulating leukocytes in microvascular vessels of rat mesentery. Exposure of rat mesentery to 10(-8)M authentic CINC/gro induced neutrophil adherence to and extravasation from postcapillary venules (PCVs) but not from capillaries or arterioles. CINC/gro concentrations as low as 10(-10) M were effective in causing neutrophil adherence. Neutrophils adhered to thin PCVs (mean diameter, approximately 25 microns) after exposure to CINC/gro for 15 min. The mean diameters of the PCV with adherence of neutrophils after exposure to CINC/gro for 30 and 60 min were 37 and 43 microns, respectively. The diameters of PCV with extravasation of neutrophils also increased in a time-dependent manner. The starting position of adherence of neutrophils was approximately 25-50 microns away from the upper junction of two vessels and remained virtually unchanged during exposure to CINC/gro for 60 min. However, the distance from the start to the end of neutrophil adherence increased in a time-dependent manner. The effect of CINC/gro on adherence and extravasation of leukocytes was neutrophil specific since other leukocytes such as lymphocytes and monocytes were not identified among the adherent and extravasated leukocytes.

Animals

Enantioselective pharmacokinetics of alpha-fluoromethylhistidine in rats and its comparison with histidine.

The enantiomer-specific pharmacokinetics of histidine and its analogue, alpha-fluoromethylhistidine (FMH), were investigated in rats. After bolus intravenous administration of each enantiomer of histidine or FMH at a dose of 40.3 mg kg-1 as free base equivalents, the plasma concentrations of L-histidine, D-histidine, (S)-FMH and (R)-FMH decreased biexponentially with half-lives of 39.2, 20.8, 32.8 and 25.0 min, respectively, in the elimination phase. Although the concentration of L-histidine in the plasma was lower than that of D-histidine, there was no large difference in plasma concentration-time curves of the enantiomers of FMH. The apparent total clearance of L-histidine from rat plasma was about 4 times that of D-histidine or the enantiomers of FMH. L-Histidine was quickly transferred to the peripheral tissues where the concentrations also decrease biphasically. L-Histidine penetrated more rapidly into the brain than either its D-enantiomer or a compound closely related in structure such as FMH. However, the disappearance of L-histidine from the various brain regions was very rapid. In contrast, brain/plasma ratios of D-histidine and (S)-FMH increased continuously after injection of these compounds, indicating that D-histidine or (S)-FMH partitioned into the brain and was very slowly removed from the brain; (R)-FMH was not distributed to the brain. These results suggested stereoselectivity in disposition of histidine and FMH enantiomers in rats.

Animals

The optical resolution of racemic chlorpheniramine and its stereoselective pharmacokinetics in rat plasma.

An ovomucoid-conjugated column has been developed for the chiral stationary-phase liquid chromatographic resolution of racemic chlorpheniramine with a quantitation limit of 0.05 microgram mL-1. The assay was used to study the stereoselective kinetics of chlorpheniramine enantiomers in rats. After bolus intravenous administration of racemic chlorpheniramine maleate (20 mg kg-1), plasma concentration of the (-)-form was higher than that of the (+)-form. In the elimination phase, the concentrations of (+)- and (-)-chlorpheniramine in the plasma declined biexponentially with half-lives of 18.2 and 50.0 min, respectively. Although there was no significant difference in blood-to-plasma concentration ratio of both enantiomers, the apparent total blood clearance of (+)-chlorpheniramine was twice as large as that of the (-)-isomer. Binding of (-)-chlorpheniramine to rat plasma protein was stronger than that of (+)-chlorpheniramine suggesting stereoselective pharmacokinetics may be due to a difference in the plasma protein binding.

Animals

Level of neutrophil chemotactic factor CINC/gro, a member of the interleukin-8 family, associated with lipopolysaccharide-induced inflammation in rats.

Rat cytokine-induced neutrophil chemoattractant (CINC), which is a counterpart of human gro and belongs to the interleukin-8 family, has been quantified by a new sandwich enzyme-linked immunosorbent assay. Administration of lipopolysaccharide (LPS) into an air pouch performed by subcutaneous injection of air caused inflammation and severe neutrophil infiltration. After the LPS injection, changes in the concentration of CINC/gro, chemotactic activity, and the number of neutrophils in the air pouch exudate were determined. The chemotactic activity of neutrophils was augmented before practical neutrophil infiltration. More than half of the chemotactic activity was neutralized by the antisera. The time kinetics of the level of CINC/gro coincided with the changes in chemotactic activity. The maximal level of rat CINC/gro was 85 ng/ml, which is sufficient to cause neutrophil migration in vitro and in vivo as described previously. These data suggest that rat CINC/gro is a functional chemoattractant for neutrophils in LPS-induced inflammation in rats.

Animals

[Effects of selenium on the serum glucose and insulin levels in diabetic rats].

We investigated the effects of selenium (Se) on the serum glucose and insulin levels in rats with diabetes induced by streptozotocin (STZ, 75 mg/kg, i.p.) and pancreatectomized rats. Moreover, the direct action of Se on insulin release from the isolated pancreatic islets using a slight diabetic rat was studied. The following results were obtained: 1) Selenite at a dose of 173 micrograms/kg (78.9 micrograms/kg of Se base equivalent) drastically reduced the very high level of serum glucose in acute diabetic rats within 5 to 30 min after treatment. During this time period, the insulin level in the serum showed an increasing tendency. 2) The high serum glucose level in chronic diabetic rats returned to the original level with injection of selenite for 4 days, once a day. However, Se did not elicit a significant increase in serum insulin level. 3) Although there was a tendency for the serum glucose level to decrease when selenite was administered into pancreatectomized rats, no secretion of insulin into the serum was observed. 4) Insulin release from isolated pancreatic islets was dose-dependently accelerated by the addition of selenite. These data present the new finding that Se reduced the high level of serum glucose in diabetic rats.

Animals

Extraversion, introversion, and visual interaction.

20 extraverts and 20 introverts were selected from a population of college students on the basis of their responses to the Maudsley Personality Inventory. These 40 young women were interviewed by one confederate of each sex. Six trained judges recorded visual and speech behavior by viewing through a one-way mirror and watching videotaped records. Analysis showed that extraverted women engaged in longer gazing than the introverted ones. The extraverted women gazed longer during listening than did introverted women. The proportion of time spent in gazing while speaking was not associated with extraversion. Also, women spent a greater proportion of time looking at a female interviewer than at a male interviewer.

Adult

[All-trans retinoic acid induced a complete remission in a case of refractory relapsed acute promyelocytic leukemia].

Forty five year old male suffering from relapsed acute promyelocytic leukemia (APL) was treated with all-trans retinoic acid (ATRA) and attained second complete remission (CR) without bone marrow hypoplasia. He was diagnosed as having APL in September 1989. The DCMP-85 regimen first induced CR in October, however the disease relapsed in September 1990. The DCMP-85 and and the MEC (MIT, ETOP, Ara-C) regimens were applied for re-induction without success. Then, 45 mg/m2/day ATRA was given orally from December 28, 1990. Laboratory data before ATRA treatment were as follows; 35.4% leukemic cells in the bone marrow, Hb 11.0 g/dl, Plt 130,000/microliters, WBC 5,100/microliters without leukemic cells, and no DIC was detected. During the treatment, his bone marrow was examined frequently. The bone marrow series showed no hypoplasia at any time and gradual reduction of leukemic cells with proliferation of mature granulocytes. CR was attained on January 21, 1991. DIC did not develop. Cytogenetic anomalies including t(14;17;15) (q24;q11.2;q22) reduced from 29/30 cells at relapse to 4/30 cells at the time of CR. Dryness of mouth and lips, irritation around eyes and the elevations of GOT, GPT and triglyceride level were seen as the side effects of ATRA, however they were tolerable.

Humans

Inhibition of prostaglandin production in the inflammatory tissue by loxoprofen-Na, an anti-inflammatory prodrug.

The effect of loxoprofen-Na, a novel non-steroidal anti-inflammatory drug with a prodrug property, on prostaglandin (PG) levels in the inflammatory tissue was investigated with a carrageenin-induced pleurisy model in rats. The intrapleural injection of carrageenin caused a marked increase in the levels of PGE2 and 6-keto-PGF1 alpha in the pleural exudate up to 3 hr after the injection. When [14C]PGE2 was injected into the cavity 2 hr after the carrageenin injection, the PG rapidly disappeared from the cavity (T 1/2 = 5 min). Thus, the PG level determined in the inflammatory exudate represents PG produced in the inflammatory tissue. Loxoprofen-Na, administered orally 2 hr after the carrageenin injection, dose-dependently inhibited the increase in the levels of PGs in the exudate 1 hr after administration (ID50 = 0.07 mg/kg for PGE2 and 0.10 mg/kg for 6-keto-PGF1 alpha). Indomethacin also inhibited PG production, but was less effective (ID50 = 0.24 mg/kg for PGE2 and 0.47 mg/kg for 6-keto-PGF1 alpha). Similar results were obtained 3 hr after the administration of these drugs (ID50 of PGE2 production = 0.14 mg/kg for loxoprofen-Na and 0.28 mg/kg for indomethacin). The time-course analysis of the effect of loxoprofen-Na showed that this drug had more immediate and stronger inhibitory activity than indomethacin. The relative potencies of suppression of protein leakage and leukocyte infiltration correlated well with the inhibition of PG production, but higher doses were needed for an obvious anti-inflammatory effect. The active metabolite (SRS trans-OH) of loxoprofen-Na determined in the inflammatory exudate 1 hr after oral administration of 0.2 and 2 mg/kg of loxoprofen-Na was 0.05 and 0.25 micrograms/mL, respectively. The concentration was sufficient to suppress PG production in the exudate, because the IC50 of the SRS trans-OH for PG production in vitro with leukocytes was 0.02 microgram/mL (0.01 microM). The potency of the SRS trans-OH metabolite to inhibit PGE2 production in leukocytes was about 20 times stronger than that of the parent compound and 3 times stronger than that of indomethacin.

6-Ketoprostaglandin F1 alpha

Insulin-like growth factor I rapidly induces tyrosine phosphorylation of a Mr 150,000 and a Mr 160,000 protein in highly metastatic mouse colon carcinoma 26 NL-17 cells.

Insulin-like growth factor I (IGF-I) stimulates the proliferation of highly metastatic NL-17 cells to a greater extent than poorly metastatic NL-44 cells, both of which are derived from mouse colon carcinoma 26. The NL-17 cells have been compared with NL-44 cells for the signal transduction pathway of IGF-I. IGF-I receptors of both cell types were identified by affinity labeling, and there was no significant difference between the two cell types in the amount or the autophosphorylation activity of the IGF-I receptors. However, when IGF-I-dependent tyrosine phosphorylation of cellular components was examined, remarkable tyrosine phosphorylation of proteins with molecular weights of 150,000 (pp150) and 160,000 (pp160) was found in NL-17 cells. In contrast, this phosphorylation stayed at significantly lower levels in NL-44 cells than in NL-17 cells. The phosphorylation of pp150 and pp160 was induced within 10 s after the addition of IGF-I and reached its maximal level by 30 s. After the removal of IGF-I, the phosphorylation of pp150 and pp160 was reduced to the basal level within 30 min. This phosphorylation was not induced by platelet-derived or epidermal growth factor. The pp150 and pp160 were not absorbed by wheat germ agglutinin-agarose. They were found in the soluble fraction of cytoplasm but not in the membrane or the cytoskeleton. The pp150 and pp160 might be endogenous substrates of IGF-I receptor kinase. These results suggest that tyrosine phosphorylation of pp150 and pp160 mediates the higher proliferative response of NL-17 cells to IGF-I.

Animals

Hypolipidemic effects of NB-598 in dogs.

NB-598, a new inhibitor of mammalian squalene epoxidase, was found to be a potent inhibitor of microsomal squalene epoxidase from dog liver. Hypolipidemic effects of NB-598 were compared with those of simvastatin (MK-733, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor) in dogs. NB-598 was found to decrease serum total cholesterol levels and increase serum squalene levels in a dose-dependent manner. MK-733 decreased serum total cholesterol and squalene levels. Both NB-598 and MK-733 decreased all classes of lipoprotein cholesterol, and they decreased low density lipoprotein cholesterol most potently. Both drugs decreased phospholipid levels in parallel with cholesterol levels. NB-598 also decreased triacylglycerol levels. After termination of drug administration, these levels returned to the control levels. The potency of NB-598 is thought to be as great or greater than that of MK-733. Moreover, NB-598 increased squalene concentrations in the feces and gallbladder bile, but it did not affect neutral sterol and bile acid concentrations. NB-598 did not affect the lithogenic index.

Animals

Mutants of Dictyostelium discoideum with altered carbohydrate moieties of contact site A.

Mutants of Dictyostelium discoideum were isolated and found to be defective in the epitope recognized by the monoclonal antibody 120 against the carbohydrate moieties of an integral membrane glycoprotein, contact site A, with the apparent molecular mass of 80 x 10(3). One mutant, HG764, did not express any contact site A and had lost cell contact resistant to EDTA. The others, including HG794, expressed a 68-kDa form of contact site A. In comparison with the parental strain HG592, HG794 showed weaker EDTA-resistant cell contact and the same degree of EDTA-sensitive cell contact. This suggested that the moieties which HG794 lacked were involved in EDTA-resistant cell contact. The 68-kDa contact site A in HG794 could be labeled with wheat germ agglutinin and incorporated [35S] sulfate. The modB mutant HL220 also expresses 68-kDa contact site A, although it cannot be labeled with wheat germ agglutinin. Therefore, the mutants HG794 and HL220 were compared by a complementation test. The diploid strain DG701 expressed 80-kDa contact site A and showed the same degree of EDTA-resistant cell contact as strain HG592. In its EDTA-resistant cell contact, HG794 was stronger than HL220. These results suggest that HG794 is a new mutant, and that there might be at least two processes in the glycosylation of 68-kDa contact site A to the 80-kDa form. The carbohydrate moieties recognized by monoclonal antibody 120 and by wheat germ agglutinin might be involved in EDTA-resistant cell contact.

Animals

Studies on hindered phenols and analogues. 2. 1,3-Benzoxathioles having SRS-A inhibiting activity.

A series of hindered phenolic 1,3-benzoxathioles (7a-l) were prepared and investigated for biological properties. Many compounds had LPO-lowering, antisuperoxide inhibiting, SRS-A inhibiting, and 5-lipoxygenase inhibiting activities. Among them, 5-hydroxy-4,6,7-trimethyl-2-propyl-1,3-benzoxathiole (7d) and 3-(5-hydroxy-4,6,7-trimethyl-1,3-benzoxathiol-2-yl)propanol (7j) were most potent in SRS-A inhibiting and 5-lipoxygenase inhibiting activities, respectively, and were selected for further development as candidate drugs for the treatment of asthma.

Animals

Effect of simvastatin (MK-733) on sterol and bile acid excretion in rabbits.

The effects of Simvastatin (MK-733), an inhibitor of 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase, on fecal and biliary excretion of sterols and bile acids were examined using rabbits. Multiple doses of MK-733 (10 mg/kg/day) for 7 days were found to increase fecal concentrations of neutral sterols in cholesterol-fed rabbits, but not to affect those of bile acids. Multiple doses of cholestyramine (750 mg/kg/day), a bile acid sequestrant, for 7 days increased fecal concentrations of neutral sterols and bile acids in normally fed and cholesterol-fed groups. MK-733 did not affect biliary neutral sterols and total bile acids in normally fed and cholesterol-fed groups. Cholestyramine decreased biliary concentrations of neutral sterols in both diet groups. Cholestyramine altered fecal and biliary composition of bile acids, but MK-733 did not. It was considered that MK-733 inhibited the absorption of cholesterol, resulting in an increase of the fecal concentration of neutral sterols in cholesterol-fed rabbits. The mechanism of action of MK-733 in the inhibition of cholesterol absorption is considered to be clearly different from that of cholestyramine. These results confirmed the conclusion in the previous experiment.

Animals

The influence of the supernatant obtained from a culture of IL-2-activated lymphocytes on human hematopoietic progenitors.

A supernatant obtained from the culture of recombinant human interleukin 2-activated lymphocytes was added to granulocyte (G)-, macrophage (M)-, and granulocyte-macrophage (GM)-progenitor assays using a plasma clot culture method. The supernatant was found to exert a suppressive influence on the colony and cluster formations of the G progenitors. This suppressive influence of the supernatant was almost completely neutralized by the addition of a combination of anti-human tumor necrosis factor alpha (HuTNF-alpha) and anti-human interferon gamma (HuIFN-gamma) antibodies, and it has been speculated that this suppressive influence of the supernatant is probably due to TNF-alpha and IFN-gamma. The numbers of M and GM progenitors increased remarkably in the assays in which the supernatant was added when compared to assays without the supernatant; this suggests that these progenitors were resistant to TNF-alpha and IFN-gamma. Among the bone marrow mononuclear cells (BMNC) excluding erythroid-rosette-forming (ERFC) or adherent cells, the influence of the supernatant on these progenitors was not significantly different. The results of our study have shown that ERFC and the adherent cells in BMNC hardly affected the appearance of the suppressive influence.

Cells, Cultured