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Biomedical subjects

H Takeuchi

Publications and source records attributed to H Takeuchi.

At least 757 records · Page 42Linked to original sources
PubMed1987

Effects of compounds related to beta-hydroxyglutamic acid (BHGA) on identifiable giant neurones of an African giant snail (Achatina fulica Férussac).

The present study aimed to further elucidate the pharmacological features, with respect to sensitivity to L-BHGA agonists, of the receptors sensitive to beta-hydroxy-L-glutamic acid (L-BHGA) in five Achatina giant neurones: PON (periodically oscillating neurone), d-RPLN (dorsal-right parietal large neurone), VIN (visceral intermittently firing neurone), RAPN (right anterior pallial neurone) and v-RCDN (ventral-right cerebral distinct neurone). Of these neurones, d-RPLN and RAPN were depolarized by L-BHGA, while PON, VIN and v-RCDN were inhibited. Threo-beta-hydroxy-DL-aspartic acid markedly depolarized d-RPLN and RAPN (effective potency quotient (EPQ) in relation to the more effective L-BHGA isomer: 1 for d-RPLN and 0.3 for RAPN). This compound produced only slight inhibitory effects on PON, VIN and v-RCDN with EPQs calculated to be less than 0.03, less than 0.03 and 0.03, respectively. On the other hand, erythro-beta-hydroxy-DL-aspartic acid at 10(-3) M was almost ineffective, except on v-RCDN where it elicited some slight inhibitory effects (EPQ: 0.01). L-Aspartic and D-aspartic acid at 10(-3) M, also had almost no effect except for slight effects of D-aspartic acid on d-RPLN (EPQ: 0.1). N-Methyl-L- and N-methyl-D-aspartic acid were slightly effective only on v-RCDN (EPQ: less than 0.01 and 0.01, respectively). The other compounds, including beta-hydroxypyrroglutamic acid (cyclic BHGA) and proline derivatives, were almost ineffective at 10(-3) M; very weak effects were occasionally observed on some neurones.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Cobaltic lysine study of the morphology and distribution of the cranial nerve efferent neurons (motoneurons and preganglionic parasympathetic neurons) and rostral spinal motoneurons in the Japanese toad.

The morphology and distribution of the cranial nerve motoneurons (except III, IV, and VI) and rostral spinal motoneurons were systematically studied in the Japanese toad (Bufo japonicus) by retrograde labelling with cobaltic lysine complex. The cobaltic lysine clearly labelled whole neurons, i.e., cell bodies, proximal and distal dendrites, and axons. The branchial motoneurons (V, VII, IX, and X) had similar morphological characteristics and formed a more-or-less continuous cell column through the brainstem. The dendrites could be grouped mainly into the dorsomedial and the ventrolateral dendritic arrays. The dorsomedial dendrites formed a dendritic plexus in the subependymal gray matter, which extended as far peripherally as beneath the ependymal layer. The ventrolateral dendrites formed a broom-like dendritic plexus in the lateral to ventrolateral white matter. They usually extended as far peripherally as the pial surface. The rostrocaudal extent of the dendritic field was also wide and usually exceeded the motor nuclear boundaries. The hypoglossal motoneurons were grouped into the dorsomedial and ventrolateral cell groups, and the latter was considered to be part of the rostral spinal motoneuron column, from their morphology and distribution. The former had well-differentiated dendrites and occupied a more medial position than the branchial motoneurons. Besides the equivalent of the dorsomedial and ventrolateral dendritic arrays of the branchial motoneurons, they had dorsal and commissural dendrites. The accessory motoneurons had morphological characteristics and a distribution pattern similar to those of the rostral spinal motoneurons rather than the branchial motoneurons. The rostral spinal motoneurons had morphological characteristics somewhat different from the branchial motoneurons and the hypoglossal motoneurons (dorsomedial group). Functional implications of the motoneuron morphology are discussed, mainly based on the present results and earlier anatomical and physiological studies of the spinal motoneurons. The present study also revealed the anatomical features of the preganglionic parasympathetic neurons supplying some cranial nerves. These neurons had small somata with less elaborate dendrites and formed an almost continuous cell column that occupied a more dorsal position than the motoneurons of the corresponding nerve. They are thought to be homologous to the salivatory nucleus and the dorsal motor nucleus of the vagus. The basic anatomical organization of the general visceral efferent column seems to be similar throughout vertebrates.

Accessory Nerve↗
PubMed1987

Morphology and distribution of the preganglionic parasympathetic neurons of the facial, glossopharyngeal and vagus nerves in the Japanese toad: a cobaltic lysine study.

We labelled the preganglionic parasympathetic neurons of the facial, glossopharyngeal and vagus nerves of the Japanese toad by applying the cobaltic lysine to the cut end of the respective nerve, and examined their morphology and distribution. These neurons form an almost continuous cell column consisting of small neurons with less elaborate dendrites, and occupy a more dorsal position than the motoneurons of the corresponding nerves. The results suggest the presence of the amphibian homologues of the salivatory nucleus and the dorsal motor nucleus of the vagus.

Animals↗
PubMed1987

Bonding behavior between two bioactive ceramics in vivo.

The purpose of this study is to examine the chemical bonding mechanism between bioactive ceramics in vivo. Two experiments were performed. In the first experiment, rectangular specimens (5 mm X 5 mm X 25 mm) of apatite-wollastonite containing glass-ceramics (designated A.W-GC) were used. In the second experiment, plates (15 mm X 10 mm X 2 mm) of A.W-GC and three types of hydroxyapatite (designated HA) were used. The sintering temperature and porosity (%) of the three types of HA were 1200 degrees C (0.4%), 1000 degrees C (4.8%), and 800 degrees C (45%), respectively. In each experiment, two pairs of specimens of identical material, one bound with silk thread, the other not bound, were implanted subcutaneously into rats. In the first experiment, bonding of only bound specimens was observed at 3 and 6 months after implantation. The observation of interface by SEM-EPMA showed that a Ca-P-rich layer formed between the two specimens. In the second experiment, bonding of both bound and nonbound A.W-GC produced identical results 1 month after implantation. For HA sintered at 800 degrees C and 1000 degrees C, bonding was observed in every specimen. This phenomenon might be caused by the chemical change of hydroxyapatite occurring at different sintering temperatures. The Ca-P-rich layer was observed between two plates. These results suggest that self-repair of bioactive ceramic is possible under certain conditions.

Animals↗
PubMed1987

Particle design of tolbutamide in the presence of soluble polymer or surfactant by the spherical crystallization technique: improvement of dissolution rate.

Poorly soluble crystals of tolbutamide were modified in the presence of a soluble polymer or surfactant by the spherical crystallization technique, the objective being to improve the dissolution rate and to transform platelet crystals into spherical agglomerates. An HCI solution was added to a tolbutamide:NaOH solution containing a water-soluble polymer or surfactant. The tolbutamide crystals were agglomerated with either and were free flowing and spherically compact. The size of the crystals of the agglomerate depended on the viscosity of the solvent and adsorption of the surfactant onto the crystal surface. The tolbutamide-agglomerated crystals dissolved isotropically, with no evidence of disintegration. The dissolution process was described in terms of the Hixson-Crowell equation. The dissolution rate of the agglomerate was 8 times faster than that of conventionally crystallized tolbutamide. Therefore, the solubility and flow-ability of tolbutamide can be improved using the spherical crystallization technique.

Crystallization↗
PubMed1987

Ionic current of an identifiable giant neurone, d-RPLN, of an African giant snail (Achatina fulica Férussac), measured under voltage clamping--II. Outward currents.

1. The outward currents of d-RPLN (dorsal-right parietal large neurone), one of the largest identifiable neurones of an African giant snail, were studied. 2. At the holding potential (-90 mV) and at the command voltage (Vc20 mV), the current values were 3.05 +/- 0.13 microA (M +/- SE) for the peak (n = 38), and 1.96 +/- 0.10 microA for the plateau (n = 37). 3. The peak time constant (Vc = 0 mV) was 2.05 +/- 0.08 msec. 4. Tetraethylammonium at 50 mM reduced the plateau value up to 50-55% of the normal, but had little effect on the peak. 5. 5-Aminopyridine at 5.0 mM diminished the peak value to about 50-55%, and delayed the peak time. 6. Quinine at 0.25 mM decreased both the peak and the plateau approximately to 55-65% of their controls, but shortened the peak time when Vc was beyond 0 mV, in contrast to the case of 4-AP. 7. The calcium-free state (replaced with cobalt) reduced these currents to about 75% of the normal, and evidently delayed the peak time.

Animals↗
PubMed1987

Effects of synthetic omega-conotoxin GVIA (omega-CgTX GVIA) on the membrane calcium current of an identifiable giant neurone, d-RPLN, of an African giant snail (Achatina fulica Ferussac), measured under the voltage clamp condition.

1. The sodium and the calcium inward currents (INa and ICa) of an identifiable giant neurone, d-RPLN (dorsal-right parietal large neurone), of an African giant snail (Achatina fulica Férussac), were measured separately under the voltage clamp condition. 2. The effects of synthetic omega-conotoxin GVIA (omega-CgTX GVIA) on the calcium current of the neuromembrane were examined. 3. omega-CgTX GVIA is a peptide venom originally isolated from a fish-hunting marine snail (Conus geographus L.); the peptide venom has been demonstrated to block markedly calcium channels in vertebrates. 4. In the case of the d-RPLN membrane, the ICa was much larger than INa. The command voltage (Vc) to get the ICa in maximum was about 0 mV; the maximum value of ICa in a representative experimental case, was measured as approximately 0.8 microA. 5. With respect to the ICa of a molluscan giant neurone, d-RPLN, synthetic omega-CgTX GVIA at a high concentration, 5 X 10(-5) M, showed almost no effect, in spite of reporting the peptide venom affecting the ICa in vertebrate preparations.

Amino Acid Sequence↗
PubMed1987

Effects of synthetic peptides on giant neurons identified in the ganglia of an African giant snail (Achatina fulica Férussac)--II.

Thirteen synthetic biologically-active peptides, which were classified into the peptides proposed as neurotransmitters in mammals and invertebrates and neural venom peptides, were investigated for their effects on the following six identifiable giant neurons of an African giant snail (Achatina fulica Férussac): RAPN (right anterior pallial neuron), INN (intestinal nerve neuron), RPeNLN (right pedal nerve large neuron), LPeNLN (left pedal nerve large neuron), d-LPeLN (dorsal-left pedal large neuron) and d-LPeCN (dorsal-left pedal constantly firing neuron). Oxytocin and proctolin at 10(-4)M excited the RAPN membrane potential, whereas FMRFamide at the same concentration inhibited the same neuron. FMRFamide at 10(-4)M markedly inhibited the d-LPeLN membrane potential, sometimes produced inhibition of RPeNLN and LPeNLN, showed varied effects (excitatory or inhibitory) on INN, and had no effect on d-LPeCN. The other peptides examined had almost no effect on any of the neurons tested.

Animals↗
PubMed1987

Effects of synthetic peptides on giant neurones identified in the ganglia of an African giant snail (Achatina fulica Férussac). IV.

1. The previous papers (Ku et al., 1986; Kim et al., 1987; Yongsiri et al., 1987) reported the effects of the synthetic peptides, i.e. Met-enkephalin, substance P, neurotensin, oxytocin, Arg-vasopressin, proctolin, FMRFamide, ranatensin C etc., on about 20 identifiable giant neurones of an African giant snail (Achatina fulica Férussac). 2. In the present study, the effects of the same peptides on the following Achatina neurones, other than those of the previous papers, were investigated: v-RPLN, v-LPSN, v-VNAN, v-VLN, r-VMN, l-VMN, v-l-VOrN and d-RCDN. 3. Of the neurones tested here, v-RPLN (ventral-right parietal large neurone) was excited slightly by Met-enkephalin, excited markedly by oxytocin, and inhibited by FMRFamide, at 10(-4) M. 4. Of these effects, those of oxytocin and FMRFamide were undoubtedly the direct effects on the neurone tested, whereas those of Met-enkephalin were probably due to the synaptic activations. 5. Another neurone, v-LPSN (ventral-left parietal large neurone), was affected by oxytocin and ranatensin C at 10(-4) M. The two substances sometimes showed similar simple excitatory effects, in other cases biphasic (excitation followed by inhibition) effects, and in a few cases almost no effect. 6. The rest of the neurones tested were not sensitive at all to any of the peptides examined.

Animals↗
PubMed1987

Enhancement of the dissolution rate of a poorly water-soluble drug (tolbutamide) by a spray-drying solvent deposition method and disintegrants.

The dissolution rate of a poorly water-soluble drug, tolbutamide, was improved by spray-drying a diluted ammonia solution of the drug containing either a low-substituted hydroxypropylcellulose (L-HPC) or partly pregelatinized corn starch (PCS) as disintegrants. With L-HPC the resultant particles were agglomerates of disintegrant with drug on the surface and within the particles, while particles formed with PCS were composed of a single core of PCS on which the drug was deposited. The deposited drug crystals were very fine because the rapid solvent evaporation restricted crystal growth. The spray-dried particles prepared with PCS had a structure similar to that of an ordered mix. The drug dissolution rate from the spray-dried particles was more rapid than that of the powdered drug alone or with disintegrant and could be attributed to separation of the layer of fine drug crystals from the surface of the particles by swelling of disintegrant. PCS enhanced the drug dissolution rate compared with systems using corn starch. The dissolution rate also depended on the drug content of the particles which was higher than that in ordered mixtures or conventional solvent deposition systems. This system described also had the advantage of avoiding the use of organic solvents.

Chemical Phenomena↗
PubMed1987

[Comparison of chemical and immunological methods in fecal occult blood testing].

Conventional occult blood testing using the chemical method has been compared with newly developed immunological testing methods; the Hemoccult slide II (HEM II) test has been widely accepted as a guaiac test but such recent tests as the Latex agglutination test (Latex) and the Enzyme Immunoassay method (EIA) have also come to be employed. Thirty colorectal cancer patients, 30 gastric cancer patients and 30 healthy persons were subjected the three above described tests during 3 consecutive days while under no restricted diet. False positive rates during this three-day testing period were 26.7% in HEM II, 93.3 in Late and 8.3% in EIA. Although the immunological testing method has the advantage of reducing the false positive rate without the need for a restricted diet it is time-consuming and expensive. Considering these results as well as our previous knowledge accrued from a mass survey, it is suggested that a new flow-chart may be found necessary, in which an initial screening is given by the chemical method and then followed by a secondary screening by the immunological method. This new flow-chart, if routinely employed, would greatly facilitate the mass screening of colorectal cancer.

Hemoglobins↗
PubMed1987

[Foreign body in the kidney associated with stone formation: report of a case].

A 56-year-old woman was admitted to our hospital with the chief complaint of fever and right flank pain. She had had pyelolithotomy on the right kidney at another hospital eleven years earlier. Plain X-ray showed eight calcified shadows in the renal area. Excretory urograms showed slight hydronephrosis on both sides. Right pyelolithotomy was performed and it disclosed foreign body stones with nuclei of silk sutures used in the previous surgery. Including our case, nine cases of suture-thread stones in the upper urinary tract were found in the Japanese literature.

Female↗
PubMed1987

[Fever attack in percutaneous nephrolithotomy and transurethral ureterolithotripsy].

We studied the fever attacks and their factors in the cases of percutaneous nephrolithotomy (PNL) and transurethral ureterolithotripsy (TUL). In PNL, fevers were significantly higher and more frequent in the cases with infected urinary stones than those with sterile stones, but prophylactic administration of antibiotics did not lower the fever or its frequency of attack. There was no significant difference between the cases of single procedure and those of multiple procedures although multiple procedures were likely to increase the frequency of fever attacks. In TUL, single J-catheter indwelling decreased fever attacks, but infection and administration of antibiotics did not affect the fever significantly. However, careful control of urinary tract infections before and after operation and of intrarenal pressure during operation are thought to be most important for prevention of fever attacks and urosepsis.

Adolescent↗
PubMed1987

[Ureteral injury in endourological treatment of renal and ureteral calculi].

Percutaneous and transurethral removal of renal and ureteral calculi was performed in 109 cases. Targeted calculi were successfully removed in 105 cases (96.3 per cent), but in five cases combined percutaneous and transurethral procedures were required. Although endourological stone removal resulted in low morbidity rates in many other series, some major complications have also been reported. They include arteriovenous fistula, colo-cutaneous fistula, nephro-duodenal fistula and ureteral avulsion. There were two severe complications in our early experience as well. In one case, a ureteral stenosis was found seven months after two sessions of percutaneous ultrasonic lithotripsy for an upper ureteral stone, and in the other case, a mid-ureteral avulsion was caused by ureteroscopic manipulation. Besides these, we experienced several minor pelvic and ureteral perforations which were easily controlled only by ureteral stent placement. Causes and management of ureteral complications in endourological treatment of renal and ureteral calculi are discussed.

Adolescent↗
PubMed1987

[Transurethral ureterolithotripsy using a rigid ureteroscope].

Eighty patients with ureteral stones underwent transurethral ureterolithotripsy using a rigid ureteroscope. In 68 of the patients (85%), the stones were removed successfully. Most of the 12 failures were removed by a percutaneous approach. The main complications of transurethral ureterolithotripsy were high fever (35%), ureteral injury (10%) and ureteral stricture (1.6%). Ureteroscopic procedures are thought to be useful in stone removal and diagnostic evaluation of abnormality of upper urinary tract.

Adult↗