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Biomedical subjects

Y Katayama

Publications and source records attributed to Y Katayama.

At least 469 records · Page 26Linked to original sources
PubMed1993

Regulation of the intracellular free calcium concentration in acutely dissociated neurones from rat nucleus basalis.

1. Neurones were acutely dissociated from the rat nucleus basalis. Whole-cell patch clamp recordings of calcium currents (ICa) and fura-2 microfluorimetric recordings of intracellular free Ca2+ concentration ([Ca2+]i) were made simultaneously. 2. Depolarization from -60 to 0 mV elicited ICa and a gradual increase in [Ca2+]i. After repolarization, ICa terminated in 0.7 ms, and [Ca2+]i recovered to control exponentially (1-5 s). 3. Both ICa and the transient [Ca2+]i increase in response to step depolarizations, were abolished in Ca2+ free extracellular solution and in Cd(2+)-containing solution. 4. Depolarizations from -90 mV to membrane potentials less negative than -40 mV induced ICa and an increase in [Ca2+]i. Depolarization to 0 mV elicited the maximum ICa, and produced the largest increase in [Ca2+]i. There was a parallel relationship between the [Ca2+]i increase and the magnitude of the ICa. 5. The [Ca2+]i increase was associated with an increase in total Ca2+ influx when the duration of the step depolarization was varied. The relationship between the total Ca2+ influx and the peak of [Ca2+]i transient reached an asymptote as total Ca2+ influx exceeded 200 pC. A similar finding was made when more than thirty action potentials were used in increasing [Ca2+]i. 6. The process of the [Ca2+]i recovery was slowed down by lowering the temperature, by an intracellular dialysis with vanadate, by extracellular application of a mitochondrial inhibitor, carbonyl cyanide m-chlorophenyl-hydrazone (CCCP), and by Na(+)-free external solution. It was unaffected by membrane potential (-50 to -130 mV). 7. When pipette solution contained a high concentration of fura-2 (200 microM), the [Ca2+]i increase per 1 pC of Ca2+ influx decreased, and the [Ca2+]i recovery was slowed. 8. The results indicate that the ICa through voltage-dependent Ca2+ channels elevates [Ca2+]i. The neurones possess a large capacity for Ca2+ buffering, and the recovery of [Ca2+]i requires both the Ca2+ pump and membrane Na(+)-Ca2+ exchange.

Action Potentials↗
PubMed1993

Postsynaptic activation at the squid giant synapse by photolytic release of L-glutamate from a 'caged' L-glutamate.

1. Pharmacological evidence suggests L-glutamate is a strong candidate as a transmitter at the giant synapse of the squid. Postsynaptic activation at the giant synapse cannot be effected by conventional application of putative neurotransmitters by iontophoresis or perfusion, apparently because the complex structure of the synapse prevents a sufficiently rapid change in concentration at the postsynaptic membrane. Flash photolytic release of L-glutamate from a pharmacologically inert 'caged' L-glutamate pre-equilibrated in the stellate ganglion of Alloteuthis or Loligo was used to determine whether L-glutamate can produce postsynaptic activation when released rapidly in the synaptic clefts. 2. The preparation, reaction mechanism and properties of the caged L-glutamate, N-1-(2-nitrophenyl)ethoxycarbonyl-L-glutamate, are described. The product quantum yield on photolysis was 0.65 (+/- 0.05). On flash photolysis glutamate release followed a single exponential time-course in the pH range 5.5-7.8. The rate constant was proportional to [H+] and was 93 s-1 at pH 5.5 and 16 degrees C in artificial sea water (ionic strength, I = 0.68 M). 3. At pH 7.8 flash photolysis of caged glutamate pre-equilibrated in the synapse caused only a slow depolarization. A second photolytic release of L-glutamate or transsynaptic activation produced no further depolarization, suggesting desensitization and inactivation of postsynaptic mechanisms by the initial pulse of L-glutamate. 4. Synaptic transmission in the giant synapse was normal at pH 5.5. Flash photolysis at pH 5.5 caused rapid production of L-glutamate within the synaptic cleft and a fast postsynaptic depolarization which generated postsynaptic action potentials.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1993

Value of urinary endothelin-1 in patients with primary vesicoureteral reflux.

By using a radioimmunoassay specific for endothelin-1 (ET-1), we measured urinary excretion of ET-1-like immunoreactivity (LI) in 63 spot urine samples of 48 patients with primary vesicoureteral reflux (VUR). And also, urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG), beta 2-microglobulin (beta-2-MG), microalbumin (Alb) and creatinine (Cr) were measured. There was no significant correlation in any of the pairs ET-1 and NAG, ET-1 and beta 2-MG, and ET-1 and Alb. Comparing the grade of reflux according to the International Classification with urinary ET-1, urinary ET-1/Cr levels in patients with grade 2, 3 and 4 VUR were higher than normal, and the ratio of more than normal urinary ET-1/Cr increased in proportion to the grade of reflux, but it conversely decreased in grade 5. In conclusion, urinary ET-1 may be an indicator of renal tubular injury in patients with primary VUR, and its meaning may be different from conventional urinary parameters.

Acetylglucosaminidase↗
PubMed1993

Evaluation of upper urinary tract dynamics by diuresis renography in patients receiving urinary reservoir operation. Comparison of full and empty reservoir.

Upper urinary tract dynamics was evaluated using diuresis renography during full and empty reservoir in 14 patients (11 men, 3 women, 13-70 years old) with intestinal urinary reservoir or intestinal bladder augmentation. Types of operation were Mainz pouch urinary diversion 5, Mainz neobladder to urethra, 5, Kock pouch urinary diversion 2, and Mainz bladder augmentation 2. Diuresis renography was performed using 99mTc-DTPA and furosemide during full and empty reservoir, and several parameters (Tmax, T75, T50, GFR) in addition to the patterns of renogram were evaluated. In the normal control, none of the parameters of the diuresis renogram with full bladder differed from those with empty bladder. In 5 of 14 patients, abnormal waves on cystometry (CMG) were found, and in 4 of these 5 patients, the patterns of diuresis renogram of full reservoir were worse than those of empty reservoir. However, the patterns of diuresis renogram of full reservoir were not different from those of empty reservoir in 9 patients without abnormal waves on CMG. In conclusion, renal injury may easily occur in patients with intestinal reservoir and abnormal waves on CMG.

Adolescent↗
PubMed1993

Successful fibrinolytic therapy using tissue plasminogen activator in acute renal failure due to acute thrombosis of bilateral renal arteries.

A 46-year-old housewife with regurgitation of mitral valve developed acute renal failure due to acute thrombosis of bilateral renal arteries after cardiac catheterization. A regional fibrinolytic therapy using transarterial infusion of tissue plasminogen activator (t-PA) was performed at 8 h after the onset, and was successful. She could be taken off hemodialysis 2 weeks after the fibrinolytic therapy, and could be successfully operated on with mitral valve replacement 7 months after that. Three years after mitral valve replacement, her serum creatinine was 148 mumol/l. This is the longest follow-up case after regional transarterial fibrinolysis of acute thrombosis of renal artery using t-PA, and this therapy is a safe and good one for acute thrombosis of renal artery.

Acute Disease↗
PubMed1993

Effect of reduced alcohol consumption on blood pressure in untreated hypertensive men.

Fifty-four untreated, mildly hypertensive men whose daily alcohol consumption was > or = 28 ml ethanol and who drank at least 4 times per week took part in a randomized, controlled crossover trial. The purpose of the trial was to test the effects of alcohol reduction on blood pressure. After a 2-week familiarization period, the participants were assigned to either a reduced alcohol drinking group or a usual drinking group for 3 weeks (experimental period 1). The situation was then reversed for the next 3 weeks (experimental period 2). The participants were requested to limit their daily alcohol consumption to zero or reduce it as much as possible for the reduced alcohol consumption period. The self-reported alcohol consumption was 56.1 +/- 3.6 (SEM) ml/day during the usual alcohol drinking period and 26.1 +/- 3.0 ml/day during the period of reduced alcohol consumption. Systolic and diastolic blood pressures in the intervention group were found by analysis of variance to be significantly lower (2.6-4.8 and 2.2-3.0 mm Hg, respectively) than those in the control group during experimental period 2 for systolic blood pressure and experimental period 1 for diastolic blood pressure. Significant (3.6 mm Hg) and nonsignificant (1.9 mm Hg) decreases in systolic and diastolic blood pressure, respectively, were observed. The method of Hills and Armitage was used, reducing ethanol in daily alcohol consumption by 28 ml. The lowering effect of reduced alcohol consumption on blood pressure was independent of changes in salt consumption, which were estimated by 24-hour urine collection and body weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

The role of bradykinin in mediating ischemic brain edema in rats.

BACKGROUND AND PURPOSE: We investigated the hypothesis that bradykinin generation may induce ischemic brain edema in spontaneously hypertensive rats. METHODS: Cerebral ischemia lasting 3 hours was produced by bilateral common carotid artery occlusion in 67 rats. After the ischemic period, the rats were reperfused. Cerebral water content and energy metabolites (adenosine triphosphate, lactate, and pyruvate), as well as plasma and tissue bradykinin, were measured. Additionally, using the same experimental paradigm, bradykinin synthesis inhibitors (aprotinin [n = 7] and soybean trypsin inhibitor [n = 7]) were administered immediately after ischemia induction to determine the relation of bradykinin generation to the progression of ischemic brain edema. RESULTS: Cerebral water content increased during the 3-hour ischemic period, peaked at 30 minutes of reperfusion, and declined thereafter. Bradykinin levels in plasma and tissue rose markedly 30 minutes after reperfusion and fell thereafter. The progressive loss of adenosine triphosphate was mirrored by the rise in lactate. In the treated groups, aprotinin and soybean trypsin inhibitor administration significantly attenuated cerebral edema (p < 0.01 and p < 0.05, respectively). The treated groups also showed less lactate accumulation and more adenosine triphosphate preservation than did the controls. CONCLUSIONS: These results demonstrate that bradykinin levels in plasma and tissue corresponded to cerebral edema progression and that bradykinin suppression decreased edema formation. These novel findings indicate that bradykinin activation augments the progression of ischemic brain edema.

Adenosine Triphosphate↗
PubMed1993

Characterization of the C alpha-dehydrogenase gene involved in the cleavage of beta-aryl ether by Pseudomonas paucimobilis.

C alpha-dehydrogenase catalyzes the oxidation of arylglycerol-beta-aryl ether at the C alpha-position, and therefore this process produces the specific substrate for beta-etherase, which cleaves beta-ary ethers (C alpha carbonyl type). Here we isolated the C alpha-dehydrogenase gene (lig D) and sequenced its nucleotides. This gene contains an open reading frame of 915 bp and the deduced amino acid sequence had a homology with the ribitol dehydrogenase family. lig D is about 1 kbp upstream of the beta-etherase gene (lig E).

Alcohol Oxidoreductases↗
PubMed1993

[Protective effects of glycerol and mannitol on delayed neuronal death in the gerbil hippocampus].

Glycerol and mannitol are used clinically as hyperosmolar agents for the treatment of brain edema. In the present study the effects of pre-ischemic treatment with glycerol or mannitol on delayed neuronal death in the gerbil hippocampal CA1 region were examined. In addition, the effects of post-ischemic treatment with glycerol were studied. Male Mongolian gerbils were subjected to transient forebrain ischemia by bilateral common carotid artery occlusion for 5 min. Skull and rectal temperatures were maintained at 36.5 +/- 0.5 degrees C from 30 min prior to occlusion through 60 min post-ischemia. In the pre-treatment study, glycerol (650 mg/kg or 1,300 mg/kg), mannitol (650 mg/kg or 1,300 mg/kg), or saline were administered intraperitoneally to the gerbils 30 min before ischemia. In the post-treatment study, 1,300 mg/kg glycerol was given immediately or 60 min after ischemia. Seven days after the ischemic episode, the brains were fixed and stained for histopathological analysis. Normal pyramidal cell counts per 1 mm length in CA1 (neuronal density, ND) were then assessed under a light microscope. ND in the sham-operated normal control group was 275.3 +/- 16.7 (mean +/- SD). In the pre-treatment study, ND in ischemic gerbils treated with saline was 14.8 +/- 5.0. ND in ischemic animals treated with glycerol (650 or 1,300 mg/kg) or mannitol (650 or 1,300 mg/kg) were 29.0 +/- 15.7, 68.2 +/- 56.7, 88.9 +/- 79.8 and 52.8 +/- 54.4 respectively. Both glycerol and mannitol, at either dose, significantly ameliorated ND. In the post-treatment study, ND in gerbils treated with saline or glycerol immediately after ischemia were 10.3 +/- 3.4 and 43.1 +/- 78.4, respectively, and 60 min after ischemia, 13.1 +/- 9.5 and 68.9 +/- 68.9, respectively. The ND in both post-treatment groups were not ameliorated significantly. These results indicate that pre-treatment with glycerol or mannitol has protective effects on delayed neuronal death in the gerbil hippocampal CA1 region, while post-treatment with glycerol does not produce any significant protection of CA1 neurons from transient ischemia.

Animals↗
PubMed1993

Thyroid dysfunction in isolated adrenocorticotropic hormone (ACTH) deficiency: case report and literature review.

A case of isolated ACTH deficiency accompanying transient primary hypothyroidism was reported along with a review of literature on isolated ACTH deficiency in Japan with special reference to its association with thyroid function. Our case, a 56-year-old woman, developed somnolence and hypoglycemia due to isolated ACTH deficiency. She also had the features of hypothyroidism, namely mounding phenomenon, muscle rigidity, increased plasma myogenic enzymes and cold intolerance. Both free T3 and free T4 were decreased, and basal as well as TRH-stimulated TSH levels were abnormally high. Plasma thyroglobulin was increased and no anti-thyroid antibodies were detected. All thyroid related physical and biochemical abnormalities disappeared after hydrocortisone replacement. A review of the literature on 103 cases disclosed that more than half the cases with isolated ACTH deficiency had a high plasma level of TSH, basal and/or TRH-induced, while the antithyroid antibodies were reported to be positive in only 13 cases. In more than 70% of such cases, the abnormality in the pituitary-thyroid axis was transient and was reversed by glucocorticoid replacement. Our case and cases in the literature indicate that the interference of thyroid hormone synthesis and/or secretion by glucocorticoid deficiency per se is the major cause of thyroid dysfunction rather than associated autoimmune thyroid disease.

Adolescent↗
PubMed1993

Concentration of gadolinium-diethylene triamine pentaacetic acid in human kidney--study on proper time for dynamic magnetic resonance imaging of the human kidney on low and high magnetic fields.

Although Gadolinium diethylene triamine pentaacetic acid (Gd-DTPA) has been used as a contrast material in magnetic resonance imaging, it is known that contrast enhancement effect disappears if the concentration of Gd-DPTA increases beyond some levels. In this study, to evaluate the proper pulse sequences for dynamic magnetic resonance imaging (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, and the signal intensity of MRI is the solutions of several concentrations of Gd-DTPA was measured. The results were; 1. 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 was 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. 2. Gd-DTPA concentration of the renal cortex ranged from 0.132 to 0.152 mumol/g tissue at 5 min after intravenous injection of Gd-DTPA 0.05 mmol/kg body weight in 7 patients with adrenal tumor or renal cell cancer, and 1 patient with both urinary bladder cancer and prostatic cancer. Seven of them showed normal renal function and the other had renal insufficiency (GFR 25 ml/min/1.48 m2). Gd-DTPA concentrations of renal medulla and renal cell cancer tissue were 0.123 and 0.108 mumol/g tissue, respectively, at 5 min after intravenous injection of Gd-DTPA 0.05 mmol/kg body weight. These results suggest that the signal intensity of renal cortex, renal medulla, and renal cell cancer tissue may linearly correlate with Gd-DTPA concentration of tissues at 5 min after intravenous injection of Gd-DTPA 0.5 mmol/kg body weight.

Adult↗
PubMed1993

Changes of bone metabolic markers in patients with bone metastases: clinical significance in assessing bone response to chemotherapy.

To determine the changes in bone metabolism in response to combined chemotherapy in patients with bone metastases (BM), we examined osteocalcin (BGP), alkaline-phosphatase (ALP), hydroxyproline (HYP), pyridinoline (PYR), and/or deoxypyridinoline (D-PYR) in 25 cancer patients. In patients without BM, serum BGP was normal and not affected by chemotherapy. In patients with BM, however, BGP was often abnormally high or low, and some patients reacted to chemotherapy with a BGP increase at 4 weeks after initiation of therapy. Such an increase was observed in the group of patients who responded favorably to therapy as judged by a decrease in bone pain and tumor-associated biochemical markers. Urine HYP, PYR, and D-PYR were high in patients with BM before therapy; D-PYR decreased transiently at 2 weeks and increased thereafter. We assume that increased bone-resorption markers along with increased bone formation markers after therapy would indicate recovery of coupled bone metabolism, as the deranged bone remodeling is improved by tumor-regression. This study suggests that BGP and D-PYR can be useful early markers to predict favorable bone response to chemotherapy in patients with BM.

Adult↗
PubMed1993

Chronic motor cortex stimulation in patients with thalamic pain.

Analysis of the authors' experience over the last 10 years has indicated that excellent pain control has rarely been obtained by thalamic relay nucleus stimulation in patients with thalamic pain. In the present study, 11 patients with thalamic pain were treated by chronic stimulation of the precentral gyrus. In eight patients (73%), the stimulation system was internalized since excellent pain control was achieved during a 1-week test period of precentral gyrus stimulation. In contrast, no clear effect was noted or the original pain was even exacerbated by postcentral gyrus stimulation. The effect of precentral stimulation was unchanged in five patients (45%) for follow-up periods of more than 2 years. In the remaining three patients, the effect decreased gradually over several months. This outcome was significantly better than that obtained in an earlier series tested by the authors with thalamic relay nucleus stimulation (p < 0.05). The pain inhibition usually occurred at intensities below the threshold for production of muscle contraction (pulse duration 0.1 to 0.5 msec, intensity 3 to 8 V). When good pain inhibition was achieved, the patients reported a slight tingling or mild vibration sensation during stimulation projected in the same area of distribution as their pain. The authors discuss the possibility that, in deafferentation pain, sensory neurons below the level of deafferentation cannot exert their normal inhibitory influences toward deafferented nociceptive neurons because of the development of aberrant connections. Thus, while stimulation of the first- to third-order sensory neurons at the level of the thalamic relay nucleus or below cannot bring about good pain inhibition in patients with thalamic pain, activation of hypothetical fourth-order sensory neurons through precentral stimulation may be able to inhibit deafferented nociceptive neurons within the cortex. None of the patients developed either observable or electroencephalographic seizure activity.

Afferent Pathways↗
PubMed1993

[Treatment of urinary tract anomalies detected by prenatal ultrasonography].

Twelve pediatric patients with antenatal diagnosed urinary tract anomalies from 1988 to 1992 in Niigata University Hospital were clinically examined. 1: All patients were diagnosed by ultrasonography. Eleven cases did not have any abnormal pregnancy and other had oligohydramnious. 2: Postnatal surgical treatments were performed in 11 cases, but antenatal therapy was not performed in any case. 3: Temporary percutaneous nephrostomy (PNS) were carried out on 7 kidneys in 6 cases during infantile period seems to be effective in preserving function of congenital obstructed kidneys.

Female↗
PubMed1993

[Experimental reconstruction of the urinary bladder using atelocollagen sponge].

An experimental reconstruction of the urinary bladder using specially designed bovine cross linked atelocollagen sponge was performed after partial cystectomy in 12 male rabbits. Bladder reconstruction with hybrid type biomaterials using both atelocollage sponge and cultured autologous cells were performed in 5 rabbits (the 1st group). The autologous cells were collected from the mucosa and muscular layer of the urinary bladder and were seeded on the atelocollagen sponge before reconstruction. Reconstruction using atelocollagen sponge without autologous cells were performed in the other 7 rabbits (the 2nd group). In 9 of these 12 rabbits, atelocollagen sponge was successfully implanted in the native urinary bladder. Histopathological findings revealed that seeded autologous cells and growth of surrounding host cells could be seen similarly in the atelocollagen sponge but these could not be differentiated by these could not be differentiated by routine histopathological techniques. In conclusion, these results showed a possibility of construction of artificial urinary tract using both atelocollagen sponge and autologous cells.

Animals↗
PubMed1993

[Evaluation of preoperative diagnosis of primary hyperparathyroidism--special reference to normocalcemic cases].

Since the opening of our clinic 117 years before, we have treated 62 cases of primary hyperparathyroidism (PHPT), among which there were 6 cases (1 male, 5 females) whose calcium levels fell within the normal range. However, in all these cases the serum ionized calcium (Ca++) levels and the serum ionized calcium/calcium ratio (Ca++/Ca ratio) were high. Moreover, in comparing them with hypercalcemic patients (56 cases), the serum Ca++ levels were significantly lower, but the (Ca++/Ca ratio) was significantly higher. Also, the excised weight of 606.1 +/- 520.3 mg was significantly smaller than that of hypercalcemic patients, which was 1,967.9 +/- 2,086.3 mg. Preoperative locations showed significantly lower levels in comparison with hypercalcemic patients by all methods including computed tomography (CT), ultrasonography, scintigraphy, and magnetic resonance imaging (MRI). In normocalcemic patients following parathyroidectomy, although the decrease in serum calcium levels was not significant, the serum Ca++ levels and the Ca++/Ca ratio decreased significantly, so that not only are they useful parameters for preoperative diagnosis of PHPT, but they are also considered necessary and indispensable for observation of the post-operative course and judging therapeutic effects including the operation. Based on our study we concluded that in multiple and recurrent stone formers with normal range of serum Ca levels, regardless of the presence or absence of local diagnosis, if the serum Ca++ level and Ca++/Ca ratio are high, existence of primary hyperparathyroidism must be suspected, and adequate treatments should be instituted promptly.

Calcium↗
PubMed1993

Measurement of myocardial blood flow in coronary artery bypass surgery.

It is now possible experimentally to measure myocardial blood flow of the beating heart using a helium-neon (He-Ne) laser Doppler flowmeter. A myocardial probe was redesigned to reduce its size and weight, and a method devised of fixing the probe to the beating cardiac surface to allow its clinical application. This modified laser flowmeter was used on 36 patients with ischaemic heart disease to measure myocardial blood flow before and after revascularization. Flow was measured in the right and left ventricles while patients were in a haemodynamically stable state as determined by electrocardiography, heart rate, blood pressure and double product (heart rate x systolic blood pressure). No significant difference was found between the mean(s.e.m.) preoperative and postoperative flow volume at the anterior wall of the right ventricle (77(15) versus 81 (12)ml/min per 100 g), which did not undergo revascularization, but mean(s.e.m.) myocardial blood flow at the ischaemic left ventricle increased significantly (from 68(15) to 88(13) ml/min per 100 g; P < 0.01). There was also no significant difference between preoperative and postoperative values of haemodynamic parameters of coronary blood flow. In conclusion, a means to measure myocardial blood flow with He-Ne laser Doppler flowmetry has been devised which shows coronary artery bypass grafting to increase myocardial blood flow in the ischaemic myocardium.

Adolescent↗