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Biomedical subjects

M Sakata

Publications and source records attributed to M Sakata.

At least 73 records · Page 4Linked to original sources
PubMed1998

Structural studies of endohedral metallofullerenes by synchrotron radiation powder diffraction.

The endohedral natures of the metallofullerenes Y@C(82) and Sc(2)@C(8)4 are described based on synchrotron radiation powder diffraction experiments. For structural analysis, a combination of the maximum-entropy method (MEM) and Rietveld refinement was employed to analyse the complicated powder pattern. The obtained MEM charge densities show a clear distinction of the endohedral natures of the mono- and dimetallofullerenes.

Journal Article↗
PubMed1998

Induction of infarct tolerance by platelet-derived growth factor against reversible focal ischemia.

Nerve growth factor, brain-derived neurotrophic factor, and other neurotrophic factors have been reported to have neuroprotective effects against global ischemia. To investigate whether the homodimer of platelet-derived growth factor B-chain (PDGF-BB) can protect neurons against focal temporary ischemia, PDGF-BB was administered to the rat brain for a prolonged period prior to, during, and after ischemia, since PDGF-BB protected rat neurons from global ischemia in our previous study. A total of 82 male Sprague-Dawley rats were used. Recombinant PDGF-BB, or saline was administered into the left neocortex via an implanted osmotic pump for 3 days (1.2 microg in total), 7 days (2 microgram or 4 microgram in total), or 14 days (4 microgram in total) pre-ischemia and 2 days post-ischemia. In an additional group, PDGF-BB (4 microgram in total) was administered for 14 days by osmotic pump and focal ischemia was induced after an additional 7-day interval following removal of the pump. Focal temporary ischemia was induced in the left MCA territory by bilateral CCA and MCA occlusion for 2 h. All rats were sacrificed 2 days after ischemia and the volume of cerebral infarct was analyzed using TTC staining. In a separate set of animals, regional cerebral blood flow (rCBF) was monitored by the hydrogen clearance method and laser Doppler flowmetry (LDF) of the neocortex after 14 days of intracerebral administration of PDGF-BB or saline. In the group receiving PDGF-BB (4 microgram in total) for 7 or 14 days pre-ischemia, there was a significant reduction of neocortical infarction compared to that in the control or saline-infused group. The size of cerebral infarct was smallest in the group that received PDGF-BB for 14 days, when ischemia was induced 7 days after removal of the pump. Regarding rCBF measurement, there were no significant differences in groups receiving PDGF-BB or saline infusion for 14 days. The potent neuroprotective effect of PDGF-BB on global ischemia was also demonstrated in the focal ischemia model. However, prolonged intracerebral infusion for 7 to 14 days was necessary to achieve a significant reduction of infarct volume. Neuroprotection was not due to increased collateral flow during ischemia.

Animals↗
PubMed1998

Arterio-venous extracorporeal membrane oxygenation of fetal goat incubated in artificial amniotic fluid (artificial placenta): influence on lung growth and maturation.

PURPOSE: The authors attempted to achieve extrauterine support of goat fetuses using arteriovenous extracorporeal membrane oxygenation (A-V ECMO) via umbilical vessels, incubated in a warm bath. They hypothesized that this extrauterine support system affected both the lung growth and maturation of goat fetuses. METHODS: Four goat fetuses at about 125 days' gestation (term, 150 days) were placed in this fetal ECMO system. Their four twin fetuses with similar body weights were harvested and examined for baseline data before ECMO (pre-ECMO data). The mean duration of A-V ECMO was 138.8+/-66.9 hours (range, 87 to 237 hours). Tracheal ligation was performed on all four fetuses to prevent the efflux of fetal tracheal fluid and to collect a sample of tracheal fluid daily. The surfactant and electrolytes of the tracheal fluid were analyzed in pre-ECMO (twin fetuses) and during ECMO. The surfactant of lung tissue, and lung weight were analyzed in pre-ECMO (twin fetuses) and after ECMO. Plasma cortisol and T3 levels were also assayed as hormonal factors that affected lung maturation in pre-ECMO and during ECMO. RESULTS: The phospholipid, phosphatidylcholine, and lecithin-sphingomyelin ratio of the tracheal fluid on day 5 during ECMO (15.0+/-7.1 mg/dL, 53.4+/-26.5%, and 6.2+/-7.1) were elevated above pre-ECMO (10.0+/-4.6 mg/dL, 43.0+/-0.6%, and 4.0+/-2.9), but there were no significant differences. The phosphatidylcholine and disaturated phosphatidylcholine of the lung tissue after ECMO were 72.3+/-15.4 mg/g and 19.2+/-8.2 mg/g, which were significantly higher than pre-ECMO (53.7+/-13.9 mg/g and 11.6+/-4.1 mg/g). The Cl- and K+ of the tracheal fluid were 123.5+/-6.2 mEq/L and 3.7+/-0.7 mEq/L on day 1 during ECMO, which were significantly lower than pre-ECMO (141.8+/-2.9 mEq/L and 6.8+/-1.1 mEq/L), but they then recovered to pre-ECMO levels. The wet and dry lung weights after ECMO were 87.8+/-18.0 g and 6.3+/-1.9 g, which were significantly higher than pre-ECMO (49.3+/-5.9 g and 4.2+/-1.3 g). Plasma cortisol levels and T3 levels during ECMO were significantly higher than pre-ECMO. Electron microscopy demonstrated a higher increase of mature type 11 cells in the lungs after ECMO than pre-ECMO. CONCLUSION: This fetal A-V ECMO system in the bath showed a production of surfactant, the maintenance of ion transport by the pulmonary epithelium, an increase in lung weight, and an increase in mature type II cells, resulting in lung growth and maturation.

Amniotic Fluid↗
PubMed1998

A new artificial placenta with a centrifugal pump: long-term total extrauterine support of goat fetuses.

PURPOSE: We tried long-term total extrauterine support of goat fetuses at high pump flow, which was pulsatile and synchronized with the cardiac cycle and at low oxygen tension in the umbilical artery and vein by use of the new artificial placenta. METHOD: This system consisted of an arteriovenous extracorporeal membrane oxygenation using umbilical artery and vein and a thermoregulated water bath. Five goat fetuses (125 +/- 0.7 days of gestation, 2.0 +/- 0.9 kg) were incubated in lactated Ringer's solution. Mean pump flow rate ranged from 113 +/- 16 to 193 +/- 13 ml/min/kg, and umbilical arterial oxygen tension was maintained at 20 +/- 3 to 23 +/- 5 mm Hg for five fetuses. RESULT: Blood gas analysis echocardiogram showed that fetal circulation and sufficient oxygen consumption could be maintained, and fetal extrauterine support conditions were made as similar as possible to physiologic circulatory conditions. We achieved long-term extrauterine support of goat fetuses up to 237 hours (mean 137 +/- 58 hours). CONCLUSION: We believe that this system can be used for experimental models of the fetus and will come into clinical application for fetal extrauterine support systems and backup systems for fetal operations.

Animals↗
PubMed1998

Identification, origins and the diurnal role of the principal serine protease inhibitors in human tear fluid.

PURPOSE: Previous work identified polymorphonuclear leukocyte (PMN) elastase as the major caseinolytic entity in tears collected after overnight eye closure. This study was designed to identify the principal serine protease inhibitors (serpins) in tears and to determine their function in the regulation of PMN cell proteases on eye closure. METHODS: Reflex and closed eye tear samples were collected by microcapillary tube and centrifuged. After reflex and closed eye supernatants (R and C) were fractionated by HPLC, samples were subjected to casein zymography and reverse zymography. Western blots were utilized to screen tears and HPLC fractions for elastase, cathepsin G and proteinase-3 and to obtain semi-quantitative data on alpha 1-protease inhibitor (alp1), alpha 1-antichymotrypsin (alpha 1-Achy), secretory leukocyte protease inhibitor (SLPI), elafin and alpha 2-macroglobulin (alpha 2-M) as well as associated complexes and products. To confirm specificity of reactivity, samples were immunoprecipitated for a given protease or serpin and screened for the coprecipitation of interacting species. RESULTS: Although R fluid contains no caseinolytic activity, it contains low levels of serpin-like activity principally in the form of SLPI (5-10 ng/microliter). Lesser amounts of alpha 2-M, alpha 1-Achy and alp1 (approximately < 1-3 ng/microliter) are also evident. C fluid is associated with very high levels of PMN cell proteases along with a approximately 5-20-fold increase in the concentrations of all of the above inhibitors. Trace levels of elafin were also detected. The concentrations of rapid reacting inhibitors exceeded that of proteases, with SLPI, alpha 1-Achy and alp1 being the principal functional entities. In atypical samples, complexes of elastase and alpha 2-M were also encountered. CONCLUSIONS: SLPI, a known antimicrobial agent and an elastase and cathepsin G inhibitor, is the principal serpin in R fluid. C fluid is associated with a marked increase in the concentrations of an array of rapid reacting serpins capable of inhibiting all known PMN cell serine proteases. In the normal closed eye, the concentration of rapid reacting inhibitors always exceeds that of proteases with C fluid also containing a functional reserve of the slow reacting inhibitor alpha 2-M.

Blotting, Western↗
PubMed1998

Induction of heme oxygenase-1 and major histocompatibility complex antigens in transient forebrain ischemia.

Recent studies strongly suggest that oxidative stresses participate in ischemia/reperfusion-induced neurodegeneration. In addition, heme oxygenase (HO) and major histocompatibility complex (MHC) antigens serve as functional molecules against oxidative stress and as self-recognition markers in the immune system, respectively. In this study, we examined the induction of HO and MHC antigens in the rat hippocampus after transient forebrain ischemia. The protein level of HO-1 was significantly enhanced after an episode of ischemia. After ischemia, HO-1 expression was observed early but transiently in the CA1 pyramidal neurons and later but continuously in glial cells. Glial cells expressing HO-1 were predominantly ameboid microglia, but not astrocytes. Ameboid microglia expressing HO-1 were predominantly localized with MHC class II antigens. These results indicate that (1) HO-1 expression in CA1 pyramidal neurons may be harmful, and (2) ischemia induces HO-1 in ameboid microglia that express MHC class II antigens, indicating a very specific microglial stress protein response.

Animals↗
PubMed1998

Cadmium uptake from apical membrane of LLC-PK1 cells via inorganic anion exchanger.

Effects of Na+, Cl-, OH- and HCO3-, and an inorganic anion exchange inhibitor (HCO3-/Cl-), 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, on Cd uptake from the apical membrane of LLC-PK1 cells were investigated to elucidate the mechanism of Cd uptake by these cells. Furthermore, the initial uptake of Cd incubated at different temperatures was analyzed by using the Arrhenius plot to test if Cd is taken up by the cells via the carrier-mediated process. The cells were incubated with 1 microM CdCl2 for 30 min. at 37 degrees in phosphate buffer containing NaCl at pH 5.5 or 7.4. Cd accumulation by the cells at pH 7.4 was about 5 times higher than at pH 5.5. Replacement of NaCl in the phosphate buffer with KCl or mannitol decreased the Cd accumulation at pH 7.4 about 80%, but had no effect at pH 5.5. The addition of 2 mM NaHCO3 to the pH 7.4 buffer containing NaCl significantly increased the Cd accumulation, and pretreatment of the cells with the inorganic anion exchange inhibitor abolished this effect of NaHCO3 on Cd accumulation. The cells were incubated for 10 min. at different temperatures with 1 microM CdCl2 in the phosphate buffer containing NaCl at pH 7.4 in the presence or absence of 2 mM NaHCO3 or at pH 5.5 in the absence of NaHCO3. In all cases, the Arrhenius plots of Cd accumulation were nonlinear. The breakpoint was observed at about 30 degrees in the Cd accumulation at pH 7.4 in the presence of NaHCO3, suggesting the involvement of a carrier-mediated process. This breakpoint was not as clear in the Cd accumulation at pH 7.4 in the absence of NaHCO3 and not observed at all at pH 5.5. These findings suggested that Cd is partially taken up from the apical membrane of LLC-PK1 cells via the inorganic anion exchanger and the uptake of Cd is more efficient at alkaline pH and in the presence of Na+, Cl- and HCO3-.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1998

Radiographic features of an aneurysmal bone cyst of the orbit.

Aneurysmal bone cyst is an unusual benign solitary lesion of bone occurring rarely in the orbit. In this report, we present computed tomography and magnetic resonance images of an orbital aneurysmal bone cyst involving the frontal bone in a 16-month-old boy. The aneurysmal bone cyst exhibited bone destruction, new bone formation of the orbital roof and fluid-fluid levels in the lesion following hemorrhage. These radiographic features may be useful for diagnosing orbital aneurysmal bone cysts.

Bone Cysts, Aneurysmal↗
PubMed1998

[Degenerative dementia of the oldest old].

We investigated seven brains from patients 99-105 years of age with a clinical diagnosis of Alzheimer-type dementia (ATD). The pathological findings were as follows. 1) These cases could be divided into two groups: cases with localized cortical atrophy in the medial part of the temporal lobe, and a case with diffuse atrophy in the cerebral cortex. Atrophied cortex in both groups showed laminar degeneration consisting of neuronal loss, neuropil loosening and astrocytosis resulting in fibrillary gliosis, which was particularly marked in the 2nd and 3rd layers of the cerebral cortex. In contrast, the structure of the six cortical layers was preserved when there was no laminar degeneration. Laminar degeneration correlated with cortical atrophy. 2) Cases with localized atrophy were further divided into two groups: group 1 (4 cases) showed small numbers of senile plaques (SPs) and large numbers of neurofibrillary tangles (NFTs' in CA1 of the hippocamupus, subiculum, and parahippohcampul gyrus, while group 2 (2 cases) showed widespread and numerous SPs and NFTs in the cerebral cortex. The distribution of SPs and NFTs in group 2 was similar to that of the case (group 3) with diffuse cortical atrophy. It was considered that group 2 was limbic type ATD and that group 3 was neocortical type ATD, because both groups met our pathological diagnostic criteria ATD. In contrast, group 1 could not be regarded as ATD because the numbers of SPs and NFTs were below those found in ATD, even though this group showed laminar degeneration the same as that of groups 2 and 3. It therefore is likely that group 1 is a unique type of degenerative dementia, pathogenetically different from ATD.

Aged↗
PubMed1997

Increase of mouse leptin production by adipose tissue after midpregnancy: gestational profile of serum leptin concentration.

The serum concentration of leptin in 10 week old virgin ICR mice assessed by RIA was 1.70 +/- 0.08 ng/ml. The serum leptin concentration in the pregnant mice mated at 10 weeks of age significantly increased from day 11 of pregnancy and reached a peak on day 17 of pregnancy (42.2 +/- 4.8 ng/ml). AFter the delivery, the serum leptin concentration rapidly decreased and reached the level of the virgin mouse on the seventh day in the puerperium. Tissue contents of leptin in the placenta, the decidua, the uterus, and the adipose tissue were between 40 to 130 ng/g wet tissue. However, leptin mRNA was expressed only in the adipose tissue and the level of leptin mRNA on days 13 and 17 of pregnancy increased 3- to 5-fold compared with that of virgin mouse. Tissue content of leptin in the adipose tissue significantly increased from day 17 of pregnancy compared with that of the virgin mouse. The m-leptin secretion from the adipose tissue also significantly increased in vitro. These results suggest that leptin, which was secreted by adipose tissue, may play important roles in mouse reproduction after midpregnancy.

Adipose Tissue↗
PubMed1997

Effects of zinc and copper on cadmium uptake by brush border membrane vesicles.

The effects of essential metals, zinc (Zn) and copper (Cu), on cadmium (Cd) uptake were investigated in brush border membrane vesicles (BBMV) isolated from the rat renal cortex and LLC-PK1 cells. BBMV were incubated with Cd in the presence or absence of Zn or Cu, and then washed with a chelating agent, EGTA, to remove Cd bound to the outer surface of BBMV. Co-incubation with Zn or Cu decreased Cd accumulation in these BBMV in a concentration-dependent manner. Kinetic analysis of the initial accumulation of Cd suggested that Cd is taken up into rat BBMV via an unsaturable component and a saturable component (K(m) = 13.8 microM, V(max) = 1.44 nmol/mg protein/min), and co-incubation with Zn significantly increased the K(m) of the saturable component without affecting the V(max), whereas Cu significantly increased the K(m)-value and decreased the V(max)-value. Increasing the osmolarity of the incubation medium slightly decreased Cd accumulation in the absence of Zn or Cu, whereas it did not decrease Cd accumulation in the presence of these metals. These results suggest the possibility that, in addition to passive diffusion, Cd is also taken up from the renal brush border membrane via carrier-mediated mechanisms that are inhibited by Zn competitively and by Cu non-competitively. Furthermore, these results suggest that: (1) Cd binds externally and internally to BBMV, (2) little Cd is transported into the intravesicular space, and (3) both Zn and Cu decrease the binding and transport of Cd.

Animals↗
PubMed1997

A subset of senile dementia with high incidence of the apolipoprotein E epsilon2 allele.

There is a subset of very elderly patients with senile dementia in whom abundant neurofibrillary tangles are present, mainly in the hippocampal region, without a significant number of senile plaques. In a retrospective neuropathological examination of 239 dementia patients, 14 were found to have this type of senile dementia. The apolipoprotein E epsilon2, epsilon3, and epsilon4 allele frequencies in this patient group were 0.39, 0.50, and 0.11, respectively. Such a high frequency of the epsilon2 allele suggests that this type of dementia is distinct from Alzheimer's disease not only from a neuropathological but also from a genetic viewpoint.

Aged↗
PubMed1997

Mercury uptake by LLC-PK1 cells: dependence on temperature and membrane potential.

The purpose of this study was to investigate the mechanism of inorganic mercury (Hg) uptake in LLC-PK1 cells, a renal tubular epithelial cell line, and to compare the results with those reported previously by us in rat renal cortical epithelial (RCE) cells in primary culture. The LLC-PK1 cells were cultured for 3-12 days, incubated with 1 microM HgCl2 in Hanks' balanced salt solution at 4 or 37 degrees C for 30 min, and washed with phosphate-buffered saline containing BAL to remove the cell membrane-bound Hg. The uptake of Hg was higher in nonconfluent cultures than in confluent cultures and higher at 37 than at 4 degrees C. In confluent culture (Day 8) Hg uptake at 4 degrees C was only 27% of that at 37 degrees C. The initial accumulation of Hg (5 min) from different concentrations of HgCl2 (0.5-50 microM) was linear and did not show a tendency toward saturation, suggesting that a carrier-mediated process was not involved. Pretreatment of cells with 10 microM FCCP, a metabolic inhibitor and a proton ionophore, 0.5 mm DIDS, an anion transport inhibitor, or 0.5 mM ouabain, a Na+/K+-ATPase inhibitor, resulted in 72, 60, and 57% reduction in Hg uptake, respectively. Furthermore, replacement of 137 mm NaCl in the incubation medium with 137 mM KCl or LiCl or 274 mM mannitol caused 30, 45, and 87% reduction in Hg uptake, respectively. These results suggest that in LLC-PK1 cells, as in RCE cells, Hg uptake is inversely related to cell density and is influenced by membrane fluidity, membrane potential, and HCO3-/Cl- transporter.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1997

Polymorphonuclear leukocyte cells and elastase in tears.

PURPOSE: To characterize the effects that mode of sampling and overnight eye closure have on the nature of caseinolytic activity recovered in tear fluid. METHODS: Reflex, open and closed (R, O and C) eye tear fluids were collected by microcapillary tubes or from the inferior formix by Schirmer strip. Microcapillary collected samples were centrifuged and recovered cells cytochemically characterized and probed by immunofluorescence microscopy, or alternatively extracted in acidic PBS. Tear supernatants, pellets and Schirmer strip extracts were subjected to casein zymography or SDS-PAGE and immunoprobed for plasmin/plasminogen. To identify caseinolytic activity, samples were immunoprecipitated with antibodies to plasmin/plasminogen or to elastase, and the immunoprecipitated materials were subjected to zymographic analysis. RESULTS: Immunoblot assays revealed R and O samples contained low levels of plasminogen (approximately 1.1 micrograms/ml) and only trace levels of plasmin (< 0.1 ng/ml). Insufficient levels of caseinolytic activity were present to allow zymographic detection. Cytochemical analysis revealed that R and O pellets consisted almost exclusively of desquamated epithelium. Immunoblot analysis revealed that C fluid was associated with an increase in plasminogen and its partial conversion to plasmin (approximately 3.2 ng/ microliter), high molecular weight covalent complexes and degradative products. Zymographic analysis disclosed much greater caseinolytic activity than could be attributed to plasmin or its cleavage products. This consisted primarily of three bands (30-26 kDa) which were identified as polymorphonuclear leukocyte (PMN) cell elastase based on size and antigenicity. This is derived from PMNs recovered from the C pellet. Elastase could also be recovered from Schirmer strips from 90% of donors, provided that the strips were extracted in sample loading buffer. The activity was restricted to the portion of the strip that had been in contact with the ocular tissue. CONCLUSIONS: The main source of caseinolytic activity in C fluid is elastase. This arises from PMNs that undergo recruitment, activation and degranulation in the C environment. In contrast, the elastase recovered in Schirmer strip extracts is derived from intact PMNs that adhere to the strip during sample collection. This would suggest that PMN cells undergo a low level of recruitment into the open eye environment.

Adolescent↗
PubMed1997

Platelet-derived growth factor-BB, but not -AA, prevents delayed neuronal death after forebrain ischemia in rats.

Our previous studies demonstrated coordinate expression of platelet-derived growth factor (PDGF) -B chain and beta-receptor in neurons at risk in the rat brain with focal ischemia. To clarify a role of the -B chain in the brain further, we examined whether PDGF-A or -B chain protects CA1 pyramidal neurons from delayed neuronal death after forebrain ischemia in rats. Pretreatment with PDGF-BB, but not -AA, at 120 ng/d for 2 days until forebrain ischemia was performed markedly ameliorated delayed neuronal death in CA1 pyramidal neurons on day 7 after ischemia. This neuroprotective effect of PDGF-BB was dose-dependent, and pretreatment with PDGF-BB at 240 ng/d showed almost complete inhibition of delayed neuronal death. In contrast, posttreatment with PDGF-BB at 120 ng/d starting 20 minutes after ischemia demonstrated no significant neuroprotective effect. The current study established marked neuroprotective actions of PDGF-BB in ischemic neuronal damage.

Animals↗
PubMed1997

IgE antibodies against midge and moth found in Japanese asthmatic subjects and comparison of allergenicity between these insects.

The specific IgE antibodies to moth (Bombyx mori) and midge (Chironomus yoshimatsui) were measured by the Pharmacia CAP system in 51 house-dust-mite-sensitive asthma patients. None of these patients had definite histories of exposure to these insects or apparent evidence of insect-induced asthma symptoms. The RAST-inhibition assay was performed to investigate cross-allergenicity between these two insects. Furthermore, IgE immunoblotting was done to study the IgE-binding components in moth and midge extracts. Thirty (59%) of these patients showed positive IgE antibodies to moth, while 25 (49%) showed positive IgE antibodies to midge. Those frequencies of positivity were similar to that for Japanese cedar pollen, which is well known to cause allergy. A significant correlation (r = 0.863) was observed between IgE antibody titers of these two insects. The results from the RAST-inhibition assay indicated cross-allergenicity between these insects and also the existence of species-specific allergens. Fifteen IgE-binding components in moth extract were observed. The most frequent IgE-binding protein was the 79-kDa (84.2%), followed by the 72-kDa (78.9%), the 82-kDa (57.9%), and the 76-kDa (57.9%) proteins. Those were considered to be major allergens in moth. Twenty-four IgE-binding components in midge extract were observed. However, no IgE-binding protein to which over 50% of patient sera reacted was observed. These results suggest that these two insects may be considered to bear important allergens and that there is cross-allergenicity between these insects as well as species-specific allergens.

Adolescent↗