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Biomedical subjects

Y Katayama

Publications and source records attributed to Y Katayama.

At least 415 records · Page 23Linked to original sources
PubMed1994

Comparison of the effects of glycerol, mannitol, and urea on ischemic hippocampal damage in gerbils.

The effects of glycerol and mannitol, as well as urea, on delayed neuronal death (DND) in the gerbil hippocampus were investigated. 20% solution of glycerol, mannitol and urea were prepared, and 6.5 ml/kg of each agent, or saline, was administered to male Mongolian gerbils intraperitoneally 30 min before ischemia. The animals were subjected to transient forebrain ischemia for 5 min. Seven days after the ischemic insult, the brains were fixed and stained for histopathological analysis. The number of normal neurons (neuronal density, ND) in a 1 mm linear length of hippocampal CA1 region was counted. ND of sham-operated group (n = 6) was 275.3 +/- 16.7 (mean +/- SD). ND in the saline-treated group (n = 6) was 14.8 +/- 5.0. ND of groups treated with glycerol (n = 6), mannitol (n = 6) and urea (n = 4) was 68.2 +/- 56.7 (p < 0.01), 52.8 +/- 54.4 (p < 0.01) and 12.0 +/- 2.5 (NS), respectively. The present study demonstrates that glycerol and mannitol have some protective effects against DND in the gerbil hippocampus, whereas urea has no effect.

Animals↗
PubMed1994

Spinal cord protection: development of a paraplegia-preventive solution.

We present a clinically available method to protect the spinal cord against ischemic or reperfusion injury and to prevent paraplegia after cross-clamping of the aorta. We separated 35 rabbits into five equal groups and clamped each animal's abdominal aorta distal to the left renal artery. We also occluded the aortas 2 cm above the iliac bifurcation for 45 minutes with inflated 5F balloon catheters. Through the catheter port distal to each balloon one of four different solutions was infused at 3 degrees C for 3 minutes at a rate of 5 mL/min (group I, uninfused control; group II, lactated Ringer's solution; group III, lactated Ringer's solution + 30 mg/kg of methylprednisolone; group IV, lactated Ringer's solution+methylprednisolone + 3 mL of 20% mannitol; group V, lactated Ringer's solution+methylprednisolone+mannitol + 10 mg/kg of vitamins E and C). We assessed the neurologic status of the hind limbs on the second postoperative day using Tarlov's criteria. The neurologic status in groups III, IV, and V was significantly superior to that of group I (p < 0.05, groups III versus I; p < 0.01, groups IV and V versus I). Spastic paraplegia occurred in 71% of group I, in 43% of group II, in 29% of group III, in 14% of group IV, and not at all in group V. The infusion of our specially blended solution with several spinal cord neuroprotective properties (hypothermia, methylprednisolone, mannitol, and vitamins E and C) achieved the best spinal cord protection against ischemic or reperfusion injury and prevented postoperative paraplegia.

Animals↗
PubMed1994

A sensitive determination of uric acid in serum using uricase/catalase/formaldehyde dehydrogenase coupled with formate dehydrogenase.

We developed and evaluated an assay for serum uric acid based on the uricase (EC 1.7.3.3)-catalase (EC 1.11.1.6)-formaldehyde dehydrogenase (FADH, EC 1.2.1.46) method coupled with formate dehydrogenase (formate:NAD oxidoreductase, FDH, EC 1.2.1.2). Formate dehydrogenase from Pseudomonas oxalaticus catalyzes the formation of NADH from formate produced by FADH. Owing to the NADH and formate oxidase activity of the FDH itself, the full reaction curve is not linear, but gradually decreases. The formation of NADH is not stoichiometric with formate removal, but is strictly proportional to it. To overcome this decrease of extinction, we added hydroxylamine hydrochloride to the FDH. The sensitivity of the full reaction in the presence of FDH was about 1.8 times that without FDH. Analysis with a Cobas Bio centrifugal analyzer revealed a linearity of up to 3.56 mmol/L. The uricase-catalase-alcohol dehydrogenase method correlated well with the uricase-peroxidase-chromogen method. Our method is more sensitive than other methods.

Aldehyde Oxidoreductases↗
PubMed1994

Effects of inhaled nitric oxide in rats with chemically induced pulmonary hypertension.

To determine the model animal with pulmonary hypertension in which nitric oxide (NO) inhalation reduces pulmonary arterial pressure (PAP), we examined the inhalation of 20-100 ppm NO gas on normal rats and rats with monocrotaline induced pulmonary hypertension. In the control group, mean PAP showed no change after spontaneous breathing of NO at the concentration of 20 to 100 ppm for 5 min. On the contrary, in both the severe (mean PAP > 40 mmHg) and moderate (mean PAP < 40 mmHg) pulmonary hypertensive groups, NO inhalation produced a prompt reduction of the mean PAP which had been elevated by monocrotaline. 20 ppm NO inhalation reduced mean PAP from 64.4 +/- 3.7 mmHg to 56.2 +/- 4.4 mmHg (mean +/- SEM, P < 0.01) in the severe pulmonary hypertensive group, from 31.0 +/- 2.0 mmHg to 24.2 +/- 0.9 mmHg in the moderate pulmonary hypertensive group (mean +/- SEM, P < 0.05). The onset of the reduction of mean PAP occurred within 30 sec after the start of NO inhalation and maximum reduction occurred within 4 min. 20 ppm NO inhalation significantly reduced mean PAP, and mean PAP was reduced dose-dependently at the concentration of 20 to 60 ppm and reaction to NO was almost constant at the concentrations of over 60 ppm.

Administration, Inhalation↗
PubMed1994

Calcium homeostasis in the presence of fura-2 in neurons dissociated from rat nucleus basalis: theoretical and experimental analysis of chelating action of fura-2.

Intracellular calcium ions (Ca2+) play important roles in cell functions. Measurements of intracellular calcium ion concentration ([Ca2+]i) are often made with the fura-2 fluorescence recording technique in various preparations including neurons. Fura-2 has, however, a Ca(2+)-chelating action which complicates the interpretation of experimental results. In this report the chelating action of intracellular fura-2 was studied by means of computer simulations. The chelating action of an endogenous Ca(2+)-binding protein, calmodulin, was also estimated. Furthermore, whole-cell patch-clamp recordings of calcium currents (ICa) and fura-2 microfluorimetric recordings of [Ca2+]i were simultaneously made from neurons which were acutely dissociated from the rat nucleus basalis. Since Ca2+ influx can be initiated and terminated by using the voltage-clamp technique, the relationship between Ca2+ influx and rapid [Ca2+]i increase was examined. The present theoretical evaluations and experimental results disclosed the relationship between fura-2 and endogenous Ca(2+)-binding proteins; fura-2 at low concentration (10 microM) did not substantially affect the endogenous Ca2+ buffering mechanisms, but at high concentration (200 microM) effectively buffered cytosolic Ca2+ instead of endogenous Ca2+ buffers. Calcium homeostasis in neurons is furthermore discussed.

Animals↗
PubMed1994

Brief increases in intracellular Ca2+ activate K+ current and non-selective cation current in rat nucleus basalis neurons.

Neurons were acutely dissociated from the rat nucleus basalis, and membrane currents (whole-cell patch-clamp) and intracellular free Ca2+ concentrations (Fura-2) were measured simultaneously from large neurons (approximately 25 microns in diameter). A brief depolarization from -60 to 0 mV for 200 ms evoked an increase in intracellular free calcium and a slow outward tail current (72 +/- 8 pA, n = 30). The outward current reversed polarity at -75.5 +/- 2.7 mV (n = 14). The tail current declined and the intracellular calcium recovered its resting level exponentially with time-constants of 1.0 +/- 0.1 s and 2.5 +/- 0.2 s, respectively (n = 17). In neurons loaded with Cs-gluconate, a similar depolarizing pulse evoked a similar increase in intracellular free calcium, but this was now followed by an inward tail current (118 +/- 8 pA, n = 44). The inward tail current reversed polarity at -27.8 +/- 3.8 mV (n = 7), and was suppressed by removal of external sodium ions. Neither outward nor inward tail currents were observed, when the external solution was calcium-free or when the pipette solution contained EGTA (10 mM). These results indicate that a depolarization causes a calcium entry and that this consequently increases both K+ conductance and non-selective cation conductance.

Action Potentials↗
PubMed1994

ATP regulates synaptic transmission by pre- and postsynaptic mechanisms in guinea-pig myenteric neurons.

Intracellular recordings were made from myenteric neurons of the guinea-pig ileum in vitro; they were classified into S and AH neurons according to electrophysiological criteria. ATP (10 nM-100 microM) inhibited excitatory synaptic potentials in the myenteric plexus; fast excitatory postsynaptic potentials and slow excitatory postsynaptic potentials of S neurons and slow excitatory postsynaptic potentials in AH neurons. This inhibitory action was reversible and dose-dependent, and was usually followed by a transient augmentation of the synaptic potentials after washing of ATP. The actions of ATP on the synaptic potentials were prevented by pretreatment with theophylline, caffeine, quinidine and 8-phenyl theophylline. The ATP analogues, ATP-gamma-s (100 nM-100 microM) and alpha-beta-methylene ATP (100 nM-100 microM) also depressed the synaptic potentials recorded from both types of neurons. The inhibitory effect of adenosine on the synaptic potentials was 10 times weaker than that of ATP. Thus, it seems clear that the presynaptic inhibition is not occurring through adenosine A1 or A2 receptors. Furthermore, ATP at high concentrations ( > or = 1 microM) augmented nicotinic fast depolarizations of S neurons produced by extracellular acetylcholine. However, ATP at the same concentrations inhibited the slow depolarizations of S and AH neurons caused by exogenous acetylcholine (muscarinic) and substance P. It is concluded that ATP regulates synaptic transmission in the myenteric plexus of the guinea-pig ileum and the sites of ATP actions are pre- and postsynaptic.

Adenosine↗
PubMed1994

Does gadolinium-diethylene triamine pentaacetic acid enhanced MRI of kidney represent tissue concentration of contrast media in the kidney? In vivo and in vitro study.

Although Gadolinium-diethylene triamine pentaacetic acid (Gd-DTPA) has been used as a contrast material in magnetic resonance imaging (MRI), it is known that contrast enhancement effect is not uniform if the concentration of Gd-DTPA increases beyond some levels. In this study, to evaluate the proper pulse sequences for dynamic MRI in the human kidney, the concentration of Gd-DTPA was quantitatively measured by inductively coupled plasma (ICP) emission spectrometry in human biological samples after administration of Gd-DTPA. The signal intensity of MRI in the solutions of several concentrations of Gd-DTPA was measured. The results were that in using a low magnetic field apparatus, signal intensity linearly correlated with the concentration of Gd-DTPA between 0 and 2.0 mumol/g under saturation recovery sequences (flip angle = 60 degrees or 90 degrees). Using a high magnetic field apparatus, signal intensity linearly correlated with the concentration of Gd-DTPA between 0 and 2.0 or 3.0 mumol/g under spin-echo or gradient-echo sequences. Gd-DTPA concentration of the renal cortex ranged from 0.132 to 0.152 mumol/g tissue at 5 min after IV injection of Gd-DTPA 0.05 mmol/kg body weight in six patients with adrenal tumor or renal cell cancer, and one patient with both urinary bladder cancer and prostatic cancer. Six of the patients showed normal renal function and the other had renal insufficiency (GFR = 25 ml/min/1.48 m2).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Protection against ischemic spinal cord injury: one-shot perfusion cooling and percutaneous topical cooling.

PURPOSE: We investigated the protective effect of two methods of hypothermia against ischemic spinal cord injury: one-shot perfusion cooling and percutaneous topical cooling. METHODS: Twenty-five rabbits were divided into five equal groups. The abdominal aorta was isolated proximally by a vascular clamp and distally by an inflated balloon catheter for 60 minutes. Group I served as control. In groups II (2.5 ml/min) and III (5.0 ml/min), hypothermic lactated Ringer's solution was infused for 3 minutes from the distal end of the catheter. Ice blocks were placed behind the backs of rabbits 30 minutes before ischemia in group IV. Group V underwent the procedures combined with those in groups II and IV (infusion of hypothermic solution plus placement of ice blocks). Another 15 rabbits underwent laminectomy at the L2 or L3 level. A temperature probe was inserted into the spinal cord to monitor cord temperature continuously during the procedures in all five groups (three rabbits per group). RESULTS: Neurologic status on the second postoperative day in groups IV and V was significantly superior to that in group I (p < 0.01), but the neurologic status of groups II and III did not differ significantly from the neurologic status of group I. The spinal cord temperature in groups II and III dropped rapidly with the infusion, but it rose again quickly. In contrast, the spinal cord was kept sufficiently hypothermic during ischemia in groups IV and V. CONCLUSIONS: We concluded that the percutaneous cooling method can keep the spinal cord sufficiently hypothermic during ischemia to lead to a significantly superior neurologic outcome.

Analysis of Variance↗
PubMed1994

Control of systemic hypertension with diltiazem, a calcium-antagonist, in patients with a mildly elevated intracranial pressure: a comparative study.

A cerebral vasodilatory action could represent a critical adverse effect of any drug used to control the systemic blood pressure (SBP) in patients with an elevated intracranial pressure (ICP), since such an action increases the ICP and thereby reduces the cerebral perfusion pressure (CPP). While several new calcium antagonists are now available, each drug exerts variable dilatory actions on the cerebral, coronary and peripheral vasculatures. Among these agents, diltiazem has been found to be sufficiently potent to control systemic hypertension but to have a less potent dilatory action on the cerebral vasculature in experimental animals. Based on such a characteristic, diltiazem appears to be an ideal drug for controlling systemic hypertension in patients with an elevated ICP. However, little has yet been investigated in the clinical setting. In the present study, the effects of three drugs, i.e., nitroglycerin, nicardipine and diltiazem, on the ICP were analysed retrospectively. Data were collected from patients who had demonstrated a mildly elevated ICP (mean ICP, 10-23 mmHg) and moderate systemic hypertension (mean SBP, 97-125 mmHg) during the period of 72 hours after surgical evacuation of spontaneous intracerebral haematomas. We reviewed the computer-based records of 385 patients, and identified 35 episodes in which the mean SBP was reduced by more than 10 mmHg by one of these three drugs alone during the initial 24 hours after haematoma evacuation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Arteriovenous malformation occluded by Masson's vegetant intravascular haemangioendothelioma and complicated with intracerebral haematoma.

A case of arteriovenous malformation occluded by Masson's vegetant intravascular haemangioendothelioma and complicated with intracerebral haemorrhage in an 18-year-old woman is reported. Marked endothelial proliferation was found in the vascular lumen of draining vein. The haemorrhage appeared to have resulted from impaired venous drainage from the arteriovenous malformation.

Adolescent↗
PubMed1994

Increased binding activity of measles virus to monkey red blood cells after long-term passage in Vero cell cultures.

Recent field isolates of measles virus (MV) obtained by using B95-8 cells have been reported not to agglutinate African green monkey red blood cells (AGM-RBC). Vero cell-adapted, plaque-forming strains derived from three field isolates at the third passage in Vero cell cultures (T8Ve-3, T11Ve-3 and N13Ve-3) also exhibited markedly decreased binding activity, as determined by infectivity-absorption and haemadsorption tests. On the other hand, binding activity of the respective strains at the twentieth passage (T8Ve-20, T11Ve-20 and N13Ve-20) increased to practically the same level as that of the Edmonston strain, a standard strain of MV passaged long-term. A membrane immunofluorescence test revealed that the decreased binding activity to AGM-RBC of T8Ve-3, T11Ve-3 and N13Ve-3 was not due to decreased expression of the haemagglutinin (H) protein on the cell surface. The deduced amino acid sequence of the H protein synthesized in T11Ve-3-infected cells was identical to that in T11Ve-20-infected cells, although a single amino acid alteration was observed when T8Ve-3 was compared with T8Ve-20. Similarly, approximately half of the N13Ve-20-infected cells synthesized an H protein identical to that produced in N13Ve-3-infected cells, and nevertheless, exhibited markedly increased haemadsorption. The present results suggest that a viral protein(s) other than the H protein contributed to the binding activity of MV to AGM-RBC.

Amino Acid Sequence↗
PubMed1994

The effects of single lung transplantation in rats with monocrotaline-induced pulmonary hypertension.

Acute haemodynamic change after single lung transplantation for primary pulmonary hypertension was evaluated using a rat transplantation model. Inbred Fisher 344 rats were administered with 40 mg/kg monocrotaline in order to induce pulmonary hypertension. The rats whose mean pulmonary arterial pressure (PAP) was over 30.0 mm Hg received a left lung isograft from a normal donor after right heart catheterization. In the control group, PAP increased after single lung transplantation. On the other hand, in the pulmonary hypertensive group, PAP was significantly decreased 60 min after the transplantation, but 3 and 6 h after the transplantation, the PAP significantly increased again. On the day after the operation, it again decreased significantly. Left-to-right lung blood flow ratio was significantly increased in rats with pulmonary hypertension compared to rats with normal pulmonary pressure on both the 1st and 3rd postoperative days. The oedema of the grafted lung was more severe in the pulmonary hypertensive group than in the control group in the acute phase. In conclusion, single lung transplantation for pulmonary hypertension shifted pulmonary blood perfusion to the grafted lung and this shift made pulmonary oedema of the grafts more severe in the acute phase. These oedematous changes, which were more pronounced in the grafts in the pulmonary hypertensive rats, might have contributed to the transient rise in PAP in those rats after single lung transplantation.

Animals↗
PubMed1994

Preparation and characterization of monoclonal antibodies against equine chondrocytes, osteoblasts and osteocytes.

Three monoclonal antibodies capable of individually recognizing chondrocytes, osteoblasts and osteocytes were prepared. EB-1 reacted with a 55-kDa antigen on the chondrocyte membrane, EB-2 with a 110-kDa antigen on the membrane of osteoblasts and/or partial osteocytes, and EB-3 with a 130-kDa antigen on the membrane of osteocytes. These monoclonal antibodies may be useful probes for studying the differentiation and maturation of osteogenic cells.

Animals↗
PubMed1994

Clinical experience with Nikkiso centrifugal pumps for extracorporeal circulation.

A comparative study of a newly developed impeller-type centrifugal pump, Nikkiso HMS-15, was made to assess the effects on hemolysis, platelet function, and renal function for extracorporeal circulation (ECC) during open heart surgery. The Bio-pump (cone-type, Medtronic) and the roller pump were used as controls. The increase of serum hemoglobin level in the Nikkiso pump was significantly lower than that in the other pumps. The decrease of platelet counts was recognized after the initiation of ECC in the three pumps whereas the levels of platelet factor 4 and beta-thromboglobulin in the Nikkiso pump group increased by far less than in the other two groups. Moreover, renal function was better maintained in the Nikkiso pump group; in particular, a significantly higher urine output was recorded during ECC and for 1 h after the termination of ECC. The results of our clinical studies suggest that the Nikkiso centrifugal pump is suitable for ECC during open heart surgery.

Extracorporeal Circulation↗
PubMed1994

Solubilization of lignin by the ruminal anaerobic fungus Neocallimastix patriciarum.

The ability of the ruminal anaerobic phycomycete Neocallimastix patriciarum to digest model lignin compounds and lignified structures in plant material was studied in batch culture. The fungus did not degrade or transform model lignin compounds that were representative of the predominant intermonomer linkages in lignin, nor did it solubilize acid detergent lignin that had been isolated from spear grass. In a stem fraction of sorghum, 33.6% of lignin was apparently solubilized by the fungus. Solubilization of ester- and either-linked phenolics accounted for 9.2% of the lignin released. The amounts of free phenolic acids detected in culture fluid were equivalent to the apparent loss of ester-linked phenolics from the sorghum substrate. However, the fungus was unable to cleave the ether bond in hydroxycinnamic acid bridges that cross-link lignin and polysaccharide. It is suggested that the majority of the solubilized lignin fraction was a lignin carbohydrate complex containing ether-linked hydroxycinnamic acids. The lignin carbohydrate complex was probably solubilized through dissolution of xylan in the lignin-xylan matrix rather than by lignin depolymerization.

Anaerobiosis↗
PubMed1994

Oxygen sensors in vascular smooth muscle.

Inhibition or activation of cellular function due to acute decreases in PO2 can be considered in terms of two different processes: 1) a sensor that monitors PO2 decreases and 2) transduction systems directed from the O2 sensor to reactions that control cellular function. We used the norepinephrine-contracted aortic smooth muscle model to study the nature of the O2 sensor and transduction system during decreased PO2-evoked relaxations. The phosphorylation potential, a measurement of kinetic energy required for ATP hydrolysis, was decreased to 30% of control at the onset of relaxation and progressively fell as muscle relaxed. The free inorganic phosphate intracellular concentration ([Pi]) was experimentally increased approximately 0.6 mM during transients that followed a rapid decrease in PO2. Relaxations to 80% of maximal force were more rapid under conditions of an augmented [Pi] than in control rings, and they occurred at a higher phosphocreatine concentration and phosphocreatine-to-free creatine ratio but at the same phosphorylation potential. Results support the operation of a cytochrome aa3 O2 sensor in the mechanism of decreased PO2-evoked relaxations and implicate an increase in [Pi] and a decrease in kinetic energy in the transduction mechanism directed at rate-limiting reactions that control force.

Adenosine Triphosphate↗