Biomedical subjects

Y Fukuda

Publications and source records attributed to Y Fukuda.

At least 379 records · Page 21Linked to original sources

PubMed1996

Monoclonal antibody C38 labels surviving retinal ganglion cells after peripheral nerve graft in axotomized rat retina.

C38 is a monoclonal antibody that labels retinal ganglion cells in both intact and axotomized rat retinas. We report here that C38 labeled retinal ganglion cells that survived after optic nerve section and peripheral nerve graft in rats. Furthermore, with combination of the retrograde labeling, we succeeded to distinguish surviving retinal ganglion cells without axonal regeneration from those with regenerating axon.

Animals↗

PubMed1996

Ca2+ responses to ATP via purinoceptors in the early embryonic chick retina.

1. The action of adenosine triphosphate on cytoplasmic Ca2+ concentration ([Ca2+]i) was studied in the retinal cell of early embryonic chicks with fura-2 fluorescence measurements. The fluorescence was measured from the whole neural retina dissected from chick embryos at embryonic day three (E3). 2. Bath application of ATP (> or = 30 microM; EC50, 128 microM) raised [Ca2+]i by the release of Ca2+ from intracellular Ca2+ stores, since the Ca2+ response to ATP occurred even in a Ca(2+)-free medium. 3. The Ca2+ response to ATP was mediated by P2U purinoceptors. An agonist for P2U purinoceptors, uridine triphosphate (UTP), evoked Ca2+ rises more potently (> or = 3 microM; EC50, 24 microM) than ATP. Agonists for P2X purinoceptors, alpha, beta-methylene ATP and beta, gamma-methylene ATP, or an agonist for P2Y purinoceptors, 2-methylthio ATP (500 microM each), caused no Ca2+ response. Suramin (100 microM) and Reactive Blue 2 (50 microM) almost completely blocked the Ca2+, responses to 500 microM ATP and 200 microM UTP. 4. The developmental profile of the Ca2+ response to ATP was studied from E3 to E13. The Ca2+ response to ATP was largest at E3, drastically declined towards E8 and decreased further until E11-13. 5. These results suggest that the Ca2+ mobilization by ATP via P2U purinoceptors is characteristic of early embryonic retinal cells.

Adenosine Triphosphate↗

PubMed1996

Recruitment order and dendritic morphology of rat phrenic motoneurons.

The detailed morphology of rat phrenic motoneurons (PMs) was studied in 40 electrophysiologically identified cells with intracellular injection of Neurobiotin. In 15 cells, the dendritic trees were fully analyzed by using path-distance analysis, and total surface area and volume were estimated. Based on their relative onset times (ROT; i.e., the time of firing onset relative to the onset of whole phrenic activity), PMs were classified into three types; early recruited (type E; ROT < 10%), late recruited (type L; ROT > 12.5%), and quiescent (type Q; not recruited under normal conditions). Dendrites constituted 93.3% of the surface area of cells and 38.9% of the cell volumes. The number of primary dendrites (nPD) averaged 10.1, and the mean number of terminations was 38.8. The combined diameters of primary dendrites of PMs correlated well with the total dendritic surface area and the number of dendritic terminations. Comparisons among cell types revealed that type Q cells had greater dendritic surface areas and volumes than type E or type L cells. With path-distance analysis, this difference was found to be due to differences between the cell types in the numbers of their dendrites, their combined dendritic lengths, and the number of their branches. The differences between these data and those available for cat motoneurons are discussed. The input resistance of PMs correlated with their total surface area but did not correlate with their somal surface area, indicating that, in rat, PM input resistance is a function of the entire neuronal membrane rather than of the somal surface alone.

Action Potentials↗

PubMed1996

Activation of lavage lymphocytes in lung injuries caused by radiotherapy for lung cancer.

PURPOSE: Radiation pneumonitis sometimes extends beyond the irradiated area of a lung and can also affect the opposite lung. Some immunological mechanisms, in addition to simple direct injury of the lungs by radiation, seem to be involved in the onset of radiation pneumonitis. To clarify such mechanisms, the effects of radiation on local inflammatory cells in lungs, in particular, lymphocytes, were examined. METHODS AND MATERIALS: A comparison was made of bronchoalveolar lavage fluid (BALF) findings from 13 irradiated patients (RT group) and 15 nonirradiated patients (non-RT group) with lung cancer. Patients who later developed radiation pneumonitis (RP group) and those who did not (RP-free group) were also compared. Using a two-color flowcytometer, radiation-induced changes in local inflammatory cells in lungs were analyzed. This included analyses of human leukocyte-associated antigen (HLADR) and intercellular adhesion molecule-1 (ICAM-1) expression on T-cells, which are though to be involved in cell activation and interactions between cells. RESULTS: The following aspects of BALF were higher in the RT group than in the non-RT group: (a) the percentage of lymphocytes and eosinophiles; (b) the incidence of HLADR-positive CD4+T-cells and HLADR-positive CD8+T-cells; and (c) the incidence of ICAM-1--positive T-cells. The following aspects of BALF were higher in the RP group than in the RP-free group: (a) the total cell counts; (b) the percentage of lymphocytes; and (c) the incidence of ICAM-1-positive T-cells. A significant relationship was seen between the incidence of ICAM-1 expression on T-cells and the number of days from the initiation of radiotherapy to the onset of radiation pneumonitis. CONCLUSION: These data suggest that irradiation can induce accumulation of activated T-cells (HLADR and ICAM-1--positive T-cells) in the lung. This accumulation may be closely linked to radiation-induced lung injury. It is also suggested that the incidence of ICAM-1--positive T-cells in BALF may serve as a useful clinical marker of radiation pneumonitis.

Adult↗

PubMed1996

Functional and morphological restoration of intracranial brachial lesion of the retinocollicular pathway by peripheral nerve autografts in adult hamsters.

Axons of adult mammals can regenerate through peripheral nerve grafts and restore the retinocollicular pathway if lesioned proximal to the retinal ganglion cell somata. Whether the grafting and subsequent reinnervation of the superior colliculus (SC) is possible in distal axotomy in the brain is a question of clinical relevance. We have deafferented the SC of adult hamsters at its brachium thus axotomizing the retinal ganglion cell axons rostral to its synaptic contact with the SC neurons. After unilateral brachium transection, a short segment of the autologous sciatic nerve was grafted to bridge the lesioned site to the SC (n = 28). As controls the brachium was transected and left ungrafted (n = 12). Functional restoration was examined 3 to 75 weeks later in grafted (n = 16) and control (n = 5) animals by recording visual evoked responses from the collicular cells. Prior to recording the grafts were visually evaluated and categorized into successfully (n = 8) and unsuccessfully (n = 8) grafted groups. To diffuse flash stimuli applied to the contralateral eye, visual evoked field potentials were recorded from all successfully grafted, but not in unsuccessfully grafted (with the exception of one animal) nor control animals. Unitary spike responses to diffuse flash stimuli were recorded exclusively from three successfully grafted animals. Morphological reinnervation was examined in the remaining grafted (n = 12) and control (n = 7) animals by anterogradely labeling the regenerating retinal axons with WGA-HRP. Axons in the grafts and their terminals in the superficial layers of the SC were clearly labeled in 8 of the grafted and none of the controls. From these results we conclude that the brachium of the SC is conducive to axonal regeneration and the peripheral nerve graft is indeed effective in restoring distally axotomized visual pathway in adult mammals.

Animals↗

PubMed1996

Synergistic effects of nafamostat mesilate rinse and Kupffer cell blockade for rat liver preservation.

We investigated the efficacy of a new rinse solution containing nafamostat mesilate (NM) (a serine protease inhibitor) for liver preservation with modulation of Kupffer cell function. Orthotopic liver transplantation (OLT) was performed in male Lewis rats after 24 h of cold storage in University of Wisconsin organ preservation solution. After OLT, survival was determined, together with assays of blood chemistry, tissue NM metabolites, and histology 3 h after OLT. NM rinse was found to have a cytoprotective effect on liver parenchymal cells, based on enzyme data showing that NM rinse reduced the release of serum alanine aminotransferase significantly in comparison with saline rinse (P < 0.05). However, the effect was not sufficient to improve the survival rate. In contrast, when the donor was treated with gadolinium chloride 24-30 h before graft harvest, NM rinse improved the survival rate to around 80% compared with 25% for saline. The assay of NM metabolites in grafted liver tissue showed that pretreatment of the donor rats with GdCl3 delayed the degeneration of NM in the liver tissue. These data demonstrate that NM rinse and Kupffer cell blockade exert synergistic effects, leading to increased survival after cold-preserved liver transplantation.

Animals↗

PubMed1996

Liver glycogen in fasted rat livers does not improve outcome of liver transplantation.

Controversy exists over how the nutritional condition of the donor liver affects transplant outcome. Some studies suggest that livers from fasted animals (liver glycogen-depleted) are more readily injured than livers from fed animals. Our previous study suggested the opposite, i.e., livers from donors fasted for 4 days were significantly more viable on orthotopic liver transplantation. Fasting may decrease the sensitivity of the liver to an inflammatory response or block Kupffer cell activation following transplantation. Thus, long-term fasting may be beneficial for reasons unrelated to liver glycogen content. In this study we attempted to separate out the roles of fasting and liver glycogen in liver transplant outcome by fasting donors for 2 days and then feeding them only glucose to elevate liver glycogen. Rats (Brown Norway) were fed (standard diet), fasted (4 days), or fasted 2 days and then fed glucose (in water) for 2 days. Livers were preserved for either 30 or 44 h in UW solution and transplanted. Four-day fasting of the donor improved the survival rate in liver transplantation (50%-100% in 30-h cold storage, 29%-83% in 44-h cold storage). However, feeding glucose for 2 days to fasted animals caused a decrease in survival in this series of transplants (40% in 30-h cold storage, 0% in 44-h cold storage). In the glucose-fed group, liver glycogen was 240% of that in the control group. This suggests that the presence of a high concentration of liver glycogen is not beneficial to the preserved and transplanted rat liver.

Animals↗

PubMed1996

Evaluation of glomerular function in individual kidneys using dynamic magnetic resonance imaging.

We used the fast field-echo technique of magnetic resonance (MR) imaging with an intravenous bolus injection of paramagnetic contrast agent to evaluate glomerular function. The time-dependent curves of changes in signal intensity observed in the renal cortex and renal medulla brought about by the paramagnetic contrast agent allowed insight into excretory kinetics. The time at which the cortical and medullary curves cross, the cortico-medullary (C-M) junction time, was delayed with a decrease in glomerular function. The mean C-M junction time in both kidneys showed a significant inverse correlation with total creatinine clearance (Ccr), indicating the glomerular filtration rate. The C-M junction time in an individual kidney also showed an inverse correlation with individual Ccr in each kidney. Results suggest that dynamic MR imaging is a useful tool in evaluating renal morphology and in evaluating semiquantitatively the glomerular function of the kidneys, singly and together, in a manner analogous to radionuclide scintigraphy.

Adolescent↗

PubMed1996

Validity of various diagnostic tests to evaluate cure of Helicobacter pylori infection.

Many diagnostic methods have been developed and used for detecting Helicobacter pylori to evaluate the success of treatment of H. pylori infection. We investigated and compared the suitability of the rapid urease test (RUT), polymerase chain reaction (PCR), 13C-urea breath test (13C-UBT), and serology with culture for evaluating cure of H. pylori infection. Forty-seven H. pylori-positive gastric ulcer patients received dual therapy of lansoprazole (30 mg u.i.d.) and clarithromycin (200 mg b.i.d.). Four weeks after the completion of treatment, RUT, PCR, 13C-UBT, and culture were performed and the negative rates of these tests were compared. Anti-H. pylori IgG antibodies were measured by enzyme-linked immunosorbent assay (ELISA) before and 4 weeks after completion of the treatment to evaluate changes of titers during the treatment. The negative rate of RUT (55%) was significantly greater than that of culture (27%). Significant declines in titers were seen in the patients who had negative culture results, while the decline in the titer was not significant in the patients who had positive results. PCR assay and 13C-UBT were suitable for the evaluation of H. pylori eradication, but RUT was not suitable, because of its sensitivity. By monitoring anti-H. pylori IgG antibody titers, therapeutic failure can be detected early after completion of treatment.

2-Pyridinylmethylsulfinylbenzimidazoles↗

PubMed1996

Glomerular basement membrane outpockets and glomerular growth in the postnatal development of the rat kidney.

Distribution of glomerular basement membrane (GBM) outpockets and dimensional growth of glomeruli were studied in the maturing stage of rat glomeruli after completion of nephrogenesis. We observed the postnatal rat glomeruli from 5 to 60 days of age by transmission electron microscopy and estimated the structural development of glomeruli by computerized morphometry. On day 5, the GBM was double in structure, possessing an epithelial and endothelial lamina densa. After day 10, the lamina densa of the GBM was single and sent branches toward the epithelial side making outpockets. There is no change in the distributional pattern of the outpockets, at least from day 10 to day 60, although they decreased considerably in number between days 20 and 40. They were found almost exclusively on the peripheral surface of the glomerulus. The rat glomeruli increased in volume constantly in this period, and the capillary volume increased more significantly than the mesangial volume. The GBM surface area increased in parallel with the glomerular tuft volume. The growing mode of capillaries was different before and after day 40; namely before day 40 elongation was predominant, whereas after day 40 widening was more pronounced. These results indicate that if the outpockets are the other site of GBM assembly after fusion of double basement membranes, the GBM must be redistributed from the peripheral to the paramesangial site to enable elongation and branch formation of capillaries during the growth of glomeruli.

Animals↗

PubMed1996

alpha-Tocopherol pretreatment protects the endocrine function of grafts against ischemic damage during heterotopic pancreatic transplantation.

Post-ischemic injury is one of the most important problems affecting successful organ procurement and transplantation. The present study was performed to determine whether alpha-tocopherol can protect the endocrine function of pancreatic grafts against ischemia-reperfusion injury during rat heterotopic pancreatic transplantation. Rats with streptozotocin-induced hyperglycemia were used as recipients. The donor pancreas was removed and subjected to warm ischemia at 37 degrees C for 30, 60, 90 and 120 min, and then transplanted into a recipient. A 30-min period of warm ischemia did not impair the endocrine function of the pancreatic grafts, which was assessed by measuring the blood glucose levels and glucose decay constants (K), and a 60-min period of warm ischemia was considered to be the critical period for reversible tissue damage. Pretreatment with alpha-tocopherol (20 mg/kg/day, i.v.) for seven days before graftectomy significantly decreased blood glucose levels to less than 200 mg/dl and significantly increased K values in the recipient rats after transplantation when compared with placebo pretreatment. These results suggest that alpha-tocopherol pretreatment can protect the endocrine function of pancreatic grafts against injury due to warm ischemia followed by reperfusion.

Animals↗

PubMed1996

Monoclonal antibody C38 recognizes retinal ganglion cells in cats and rats.

We developed monoclonal antibody C38 which specifically recognizes retinal ganglion cells (RGCs) in flatmount preparations of cat and rat retinas. We first induced immunological tolerance in Balb/c mice against axotomized rat retinas which lack most of the RGCs. Then the mice were immunized with intact rat retinas to produce antibodies against RGCs. Monoclonal antibody C38 appeared to be specific for cat RGCs based on immunoreactivities seen in flatmounts and vertical sections of the retina. In rats, we verified that over 90% of retrogradely labeled RGCs were immunoreactive for C38 antibody. In axotomized rat retinas, surviving RGCs were labeled with C38 without erroneous labeling of glial cells. The antigen that C38 recognized was 24 kDa in molecular weight and found in cerebrum, cerebellum, and spinal cord as well as retina. It is suggested that monoclonal antibody C38 is a useful label for RGCs.

Animals↗

PubMed1996

The effect of damage of the brachium of the superior colliculus in neonatal and adult hamsters and the use of peripheral nerve to restore retinocollicular projections.

Using horseradish peroxidase (HRP) tracing technique, we were able to confirm the critical age in hamsters as reported previously (SO et al., 1981). Thus, following transection of the retinal fibers at the brachium of the superior colliculus (BSC) on postnatal-day 4 (P4) or later, no retinocollicular projections were observed in the adult stage. However, the retinal fibers were observed to reinnervate the superior colliculus (SC) if the BSC was cut on P3 or earlier. Physiological recording showed a close to normal retinocollicular map following a BSC damage on P0. Although retinal fibers did not reinnervate the SC following a BSC cut on or after P4, they could be observed to grow along a membrane over the damaged site. Bridging the site of BSC damage in adult hamsters using a segment of peripheral nerve (PN), retinal fibers labelled with WGA-HRP were observed to reinnervate the SC along the PN graft and visual evoked responses could be recorded in the SC showing the PN graft is effective in restoring damaged central visual pathways in adult mammals.

Animals↗

PubMed1996

Muscarinic and purinergic Ca2+ mobilizations in the neural retina of early embryonic chick.

Acetylcholine and adenosine triphosphate (ATP) raise intracellular Ca2+ concentration via muscarinic receptors and P2U purinoceptors by releasing Ca2+ from intracellular Ca2+ stores in the neural retina of early embryonic chick. The signal transduction mechanisms for the muscarinic and purinergic Ca2+ responses were studied with fura-2 fluorescence measurements. Li+ (1 mM), which inhibits phosphatidylinositol metabolism, enhanced both the Ca2+ rises to carbamylcholine (CCh. 30 microM) a muscarinic agonist and ATP (200 microM). Thapsigargin (250 nM), an inhibitor of Ca(2+)-ATPase of inositol trisphosphate (IP3)-sensitive Ca2+ stores, abolished both the Ca2+ rises to CCh (100 microM) and ATP (500 microM). U-73122 (2 microM), an inhibitor of phospholipase C beta, suppressed the Ca2+ rise to ATP (500 microM), but its analog U-73343 (2 microM) did not suppress it. In contrast, both U-73122 and U-73343 suppressed the Ca2+ the Ca2+ rise to CCh (100 microM). Pertussis toxin (250 ng/ml) suppressed the ATP-induced Ca2+ rise at least partly, whereas no inhibition was observed on the CCh-induced Ca2+ rise. Cross-talk occurred between the muscarinic and purinergic Ca2+ mobilizations but they were not occlusive. This study suggests that the muscarinic and purinergic Ca2+ mobilizations utilize IP3-sensitive Ca2+, stores, but different signal transduction pathways are involved in between the muscarinic and purinergic Ca2+ responses.

Acetylcholine↗

PubMed1996

Transport of drugs across the Xenopus pulmonary membrane and their absorption enhancement by various absorption enhancers.

PURPOSE: The permeability of drugs across the Xenopus pulmonary membrane and the effects of various absorption enhancers on their absorption were examined using an in vitro Ussing chamber technique. METHODS: Phenol red and fluorescein isothiocyanate-labeled dextrans (FDs) with different molecular weights were chosen as water-soluble model drugs. Absorption enhancers used in this study were N-lauryl-beta-D-maltopyranoside (LM), linoleic acid-HC060 mixed micelle (MM), sodium glycocholate (Na-GC), sodium caprate (Na-Cap), sodium salicylate (Na-Sal) and disodium EDTA (EDTA). RESULTS: The permeability of drugs gradually decreased with increasing their molecular weights, and the absorption of phenol red significantly increased by these absorption enhancers. Among these additives, LM, MM and Na-Cap appeared to be more effective for enhancing the permeability of drugs than the others. Furthermore, we plotted the logarithm of apparent permeability coefficient (Papp) of these drugs against the logarithm of their molecular weights. There exists a good correlation between these parameters. We measured transmembrane resistance(Rm) of Xenopus pulmonary membrane during the transport experiment to examine the membrane integrity. The average Rm value was about 700 omega.cm2, and this value was maintained for 3 hr. CONCLUSIONS: This method is useful for estimating the transport characteristics of drugs across the pulmonary membrane.

Absorption↗

PubMed1996

Enhanced expression of PAI-1 in visceral fat: possible contributor to vascular disease in obesity.

The presence of obesity increases the risk of thrombotic vascular diseases. The role of fat accumulation and its effect on plasminogen activator inhibitor-1 (PAI-1) levels was investigated in humans and animals. Plasma PAI-1 levels were closely correlated with visceral fat area but not with subcutaneous fat area in human subjects. PAI-1 mRNA was detected in both types of fat tissue in obese rats but increased only in visceral fat during the development of obesity. These data suggest that an enhanced expression of the PAI-1 gene in visceral fat may increase plasma levels and may have a role in the development of vascular disease in visceral obesity.

3T3 Cells↗

PubMed1996

Assessment of microchimerism in rat liver transplantation by polymerase chain reaction.

Mixed chimerism has been demonstrated in organ transplant recipients surviving over a long period. However, little is known about the fate and movements of donor cells following liver transplantation. In this study, using rat male-to-female liver transplantation, we assessed microchimerism by semiquantitative polymerase chain reaction (PCR). A PCR specific for the Y-chromosome (sex-determining region Y [Sry]) allowed the distinction of small amounts of male cells in a large excess of female cells. Nonimmunosuppressed Lewis recipients of Lewis liver grafts survived >60 days, and donor cells were detected in peripheral blood up to day 60 in four of six recipients. All immunosuppressed Lewis recipients survived for 60 days, and the donor cells were detected up to day 60. Semiquantitative PCR demonstrated that in immunosuppressed Lewis recipients surviving >60 days with no acute rejection episode, the donor-to-recipient cell ratio remained >1:1,000. In nonimmunosuppressed Lewis recipients of ACI liver allografts, donor cells in peripheral blood decreased rapidly by day 7. In immunosuppressed Lewis recipients of ACI liver allografts, donor cells were detected for longer periods, in proportion to the amount and duration of FK506 (Fujisawa Pharmaceutical Co., Osaka, Japan) administered. However, in recipients with deteriorating function due to ongoing rejection, small amounts (0.01 percent) of donor cells were detected. Our results indicate that the Sry-specific PCR is useful for assessing microchimerism following rat liver transplantation, and demonstrate correlation between microchimerism and graft outcome; high-level microchimerism (>O.l percent) correlated well with graft acceptance, whereas low-level microchimerism (<O.01 percent) did not.

Animals↗

PubMed1996

Partial purification and characterization of a novel soybean protease which is inhibited by Kunitz and Bowman-Birk trypsin inhibitors.

A novel serine protease has been partially purified from dry seeds of the soybean (Glycine max) cultivar Keburi by cryoprecipitation at pH 6.4, fractional precipitation with ammonium sulfate, and a series of column chromatographic procedures on DEAE-Sepharose, SP-Sepharose, and Arginine-Sepharose 4B. Some properties of the purified enzyme were studied. The protease hydrolyzed the native storage globulins of soybean seeds, such as the alpha subunit of beta-conglycinin, at a pair of arginine residues, Arg126-Arg127. The proteolysis of the alpha subunit in the purified alpha 2 beta molecule of beta-conglycinin apparently followed first order kinetics. The enzyme was inhibited by both soybean Kunitz trypsin inhibitor and Bowman-Birk proteinase inhibitor in a competitive manner. Moreover, the enzyme could catalyze the specific proteolysis of the A3 polypeptide of the purified G5 glycinin at the Arg99-Gly100 linkage, or the carboxyl side of the Arg98-Arg99 paired basic residues.

Amino Acid Sequence↗