Biomedical subjects

T Ichikawa

Publications and source records attributed to T Ichikawa.

At least 451 records · Page 25Linked to original sources

PubMed1990

Axonal trajectories of inhibitory vestibulocollic neurons activated by the anterior semicircular canal nerve and their synaptic effects on neck motoneurons in the cat.

Somatic location, axonal trajectories and synaptic effects of inhibitory vestibulocollic neurons which were activated by selective stimulation of the anterior semicircular canal nerve (ACN) were studied in the anesthetized cat. ACN stimulation evoked disynaptic inhibitory postsynaptic potentials (IPSPs) in neck flexor motoneurons. This was seen in all the (64/64) tested motoneurons innervating the ipsilateral (i-) longus capitis (LC) and the i-sternocleidomastoideus (SCM) muscles and in 86% (38/44) of the motoneurons innervating the contralateral (c-) LC muscle. The inhibitory relay neurons, identified by orthodromic and antidromic responses to stimulation of the ACN and the i- and c-LC motoneuron pools, were classified as VCi (vestibulocollic neurons sending an axon to the i-LC motoneuron pool) and VCc (vestibulocollic neurons sending an axon to the c-LC motoneuron pool) neurons. Neither VCi nor VCc neurons were activated antidromically by localized stimulation of the ascending medial longitudinal fasciculus (asc. MLF) or the 3rd nuclei. They were located in the medial, descending and ventral lateral vestibular nuclei. It was also observed that VCi neurons produced unitary IPSPs in i-LC and i-SCM motoneurons in the C1 segment. Inhibitory synapses were estimated to be on the cell somata and/or the proximal dendrites of the motoneurons.

Animals↗

PubMed1990

Evidence for the expression of the rol genes of Nicotiana glauca in genetic tumors of N. glauca X N. langsdorffii.

Thus far, no evidence has been presented that the rol genes (Ng rol) of Nicotiana glauca (Furner et al. 1986) are expressed in this plant. However, we found that the Ng rol genes were transcribed in genetic tumors formed in hybrids of N. glauca X N. langsdorffii. During the culture of such genetic tumors, the level of transcription of Ng rol B increased while that of Ng rol C decreased in parallel with an increase in the endogenous auxin level in the tissues. Moreover, the transcription of these genes was completely suppressed by the application of exogenous auxin. Since the measured endogenous level of auxin was rather low, the formation of tumors in these hybrids can be tentatively explained as a consequence of the expression of rol genes that is responsible for the increased sensitivity to auxin of the hybrids. This novel finding is discussed in relation to the cause of genetic tumors in Nicotiana.

Blotting, Northern↗

PubMed1990

New plastic-coated coaxial catheter system for superselective hepatic catheterization: technical note.

With the use of a new improved coaxial catheter system, superselective hepatic catheterization has become easier. The improvements consist of a decrease in the outer and an increase in the inner diameters of the coaxial catheters from 0.98 to 0.96 mm and from 0.55 to 0.65 mm, respectively, and thickening of core guidewire material from 0.014 inch (0.35 mm) to 0.018 inch (0.40 mm). With this new catheter system, it is possible to inject contrast medium (iopamidol 300) at a higher rate (3 ml/sec) and gelatin sponge particles instead of gelatin powder for arterial embolization. The success rates for superselective catheterization using conventional (n = 10 procedures) and the improved coaxial catheter systems (n = 7) were 30% and 86%, respectively.

Catheterization↗

PubMed1990

N-myc gene amplification and other prognosis-associated factors in neuroblastoma.

The correlation between N-myc gene amplification and heretofore known prognosis-associated factors was studied in 23 cases of neuroblastoma, comprising a total of 29 tumors (23 primary and six metastatic), examined in and after 1983. DNAs were extracted from tumor tissues preserved at -70 degrees C and digested with the restriction enzyme EcoRI. Southern blotting analysis was performed on these DNAs with the N-myc probe labelled with alpha-32P-dCTP. Prognosis-associated factors studied were age at diagnosis, stage, primary site, histological type, blood biochemistry tests, and catecholamine metabolites in urine. Amplification of N-myc gene was observed only in the cases in which primary site was the adrenal gland, but the relation to the stage, histological type, and prognosis was not as apparent as reported by other investigators. However, the amounts of catecholamine metabolites were low in the cases with amplification, and this suggests immaturity of catecholamine metabolism in the tumor with N-myc gene amplification.

Blotting, Southern↗

PubMed1990

Trial production and application of an optical system for measuring the movements of organs composed of soft tissue.

A new optical system to measure movements of less accessible organs composed of soft tissue is proposed. The sensor unit is composed of a phototransistor and two light-emitting diodes (LEDs). The LEDs act as light sources and are driven by two phase signals with a phase shift of 90 degrees. The distance between the sensor and the measuring object can be obtained as a function of the phase angle of reflected light detected by the phototransistor. This system can be easily constructed and simultaneously records data from multiple points in real time. The relative precision was 0.5 mm and the resolution was 0.05 mm. Output characteristics of this system were not significantly affected by the reflection factor of the object. Tongue movements in speech production were observed by use of this system.

Analysis of Variance↗

PubMed1990

Myoclonus with burning sensation in legs that remits with sympathetic blockade.

Two patients with hitherto unrecognized spells of involuntary movements in legs are described. They occurred on dropping off to sleep, were preceded by a burning sensation and resembled myoclonus. Subcutaneous injection of epinephrine reproduced the spells. Neurogenic bladder of uninhibited type was noted on cystometry. Epidural or sympathetic nerve block of the lumbar region relieved all the symptoms including the neurogenic bladder. A few minutes before the spells, a rise in blood pressure and pulse rate was observed in one of the cases. Pathophysiological resemblance to painful legs and moving toes was pointed out, but more widespread involvement of the spinal cord was suspected.

Adrenocorticotropic Hormone↗

PubMed1990

Complementary DNAs for choline acetyltransferase from spinal cords of rat and mouse: nucleotide sequences, expression in mammalian cells, and in situ hybridization.

Complementary DNA clones containing the entire coding region of choline acetyltransferase (ChAT) were isolated from the spinal cords of rat and mouse. The cDNAs of rat and mouse coded for 640 and 641 amino acids, respectively, and showed 95% mutual homology and 80% homology with the cDNA of porcine ChAT. Northern blot analysis revealed a single band of 4.4 kb in the spinal cord and brain in each species. Introduction of the cDNAs into Chinese hamster ovary cells and neuron-derived cell lines, N1E115 and NG108-15, expressed a high ChAT activity, which was inhibited by a specific ChAT inhibitor. In situ hybridization using the rat cRNA probe revealed specific labeling of the motoneurons in the spinal cord and neurons in various forebrain nuclei of the rat where the existence of cholinergic neurons has been demonstrated immunohistochemically.

Amino Acid Sequence↗

PubMed1990

A single recessive non-MHC diabetogenic gene determines the development of insulitis in the presence of an MHC-linked diabetogenic gene in NOD mice.

To study the genetic control of insulitis in non-obese diabetic (NOD) mice, we performed breeding studies in crosses of NOD with non-diabetic strains, ICR-L-line Ishibe (ILI), non-obese non-diabetic (NON) and C3H/He mice. The ILI mouse serologically shared the same MHC Class I and Class II as the NOD mouse. Insulitis was defined as islets invaded by lymphoid cells. Periductular, perivascular and peri-insular lymphoid cell infiltrations were often observed in NOD mice and appear to be the initial lesion leading to insulitis. Such lesions, however, were found in 1-year-old ICR, ILI, NON and Cataract Shionogi (CTS) mice of the NOD's sister strain. The lymphoid cells did not invade the islets in ICR, ILI, NON and CTS mice. The incidence of insulitis was 0% in F1 generations and 40% in female backcrosses (BC) [(ILI x NOD)F1 x NOD] at 9 weeks of age, 48 and 50% in BC[(NON x NOD)F1 x NOD] and BC[(C3H/He x NOD)F1 x NOD] at 1 year of age, respectively. Backcross animals were typed for the MHC to investigate correlation between the development of insulitis and MHC haplotypes. Among the backcross females with insulitis, approximately half the animals were heterozygous for MHC(non/nod) in BC[(NON x NOD)F1 x NOD] and MHC(k/nod) in BC[(C3H x NOD)F1 x NOD]. Among the backcross females with no insulitis, approximately half the animals were homozygous for MHC(nod/nod) in BC[(NON x NOD)F1 x NOD] and in BC[(C3H x NOD)F1 x NOD]. The results suggest that a single recessive non-MHC diabetogenic gene determines the development of insulitis regardless of NOD MHC homozygosity or heterozygosity.

Animals↗

PubMed1990

Encapsulated paravesical foreign body.

A large, round, paravesical mass was surgically removed from a 65-year-old man. The mass was an encapsulated aseptic granuloma surrounding a gauze that was left in situ 10 years previously at hernioplasty.

Aged↗

PubMed1990

Auditory brain stem response (ABR) in eating disorder.

Auditory brain stem responses were recorded in 10 eating disorder patients and 10 normal control subjects. Absolute latencies, interwave latencies, absolute amplitudes, and amplitude ratios were investigated. A nonsignificant difference was found between the eating disorder group and the normal control group as far as the absolute latencies and interwave latencies were concerned. But the eating disorder patients had significantly smaller amplitude ratios (III/I, IV-V/I) and absolute amplitude (V) than did the control subjects. These findings suggest that some dysfunction exists in the region of brain stem. It may be related with the pathophysiology in patients with eating disorder.

Adolescent↗

PubMed1990

Characterization and regulation of sex-specific mouse steroid hydroxylase genes.

We characterized the genes of the male-specific mouse steroid 16 alpha-hydroxylase (C-P-45016 alpha) and the female-specific mouse steroid 15 alpha-hydroxylase (P-45015 alpha) within two distinct gene families. In spite of the high structural identities within each family, the expression of the hydroxylase genes is uniquely regulated. Moreover, the other family members encode the P-450s which are structurally very similar to the hydroxylases but are not able to catalyze steroid hydroxylase activities. For example, only a single amino acid substitution creates steroid 15 alpha-hydroxylase activity in another family-member P-450coh, which catalyzes coumarin 7-hydroxylase but little steroid hydroxylase activity. It appears, therefore, that the mouse P-450 gene families evolved through gene duplication and selective mutation to create new P-450s structurally as well as to establish novel regulatory elements for the gene expressions.

Amino Acid Sequence↗

PubMed1990

Spectral sensitivities of elementary color-coded neurons in butterfly larva.

1. Response properties and spectral sensitivities of a functional class of medulla neurons that received dominant input from a single stemma in the swallowtail butterfly larva were examined with regard to neutral and chromatic backgrounds. 2. Eight types of neurons were dominated by a dichromatic stemma with blue and green receptors. Six showed specific color-opponent responses mediated by two receptors on different backgrounds; one showed strong color opponency because of fairly balanced antagonistic input on the neutral (dark and white) background; the other five usually had weak or concealed color opponency on a neutral background but became strongly color opponent when appropriate chromatic illumination was present on the background. The most complex neuron gave excitatory responses on a dark background, inhibitory responses on a white background, and color-opponent responses on a chromatic (yellow) background. 3. The remaining two types of neurons dominated by the dichromatic stemma showed non-color-opponent and broad action spectra ascribable to a synergistic effect of the two classes of photoreceptors. 4. All eight types of neurons dominated by a trichromatic stemma (with UV, blue, and green receptors) were color opponent. Five showed strong color-opponent responses with the mediation of the three classes of receptors or only two (UV and green) on a neutral background. The others revealed distinct color opponency in the presence of UV or green illumination on the background. 5. The larval medulla neurons described may form parallel, elementary color-coded channels in the medulla neuropile to combine the outputs of the different color receptors in a single visual unit (stemma) into specific color-opponent signals. They probably correspond to columnar relay neurons in the medulla of the adult insects with a compound eye.

Animals↗

PubMed1990

Assessment of mitral regurgitation using gated radionuclide ventriculography: analysis of left atrial time activity curve.

The authors analyzed the left atrial (LA) time activity curve (TAC) in 18 normal subjects and 30 patients with mitral regurgitation (MR) to assess the usefulness of radionuclide ventriculography (RNV) in detecting MR. The LA TAC was generated from gated blood pool images using phase and amplitude images. The configuration of normal LA TAC was M shaped. The first peak and last peak of LA TAC were represented as points B and D, respectively. In addition, the trough following B was named point C. The presence and severity of MR was analyzed by use of three methods: (1) analysis of LA TAC, (2) analysis of left ventricular TAC, and (3) measurement of the stroke count ratio of left ventricle to right ventricle. In the diagnosis of MR using RNV, the rapid emptying fraction [REF:(B-C)/(B-A)] of LA TAC was the most sensitive index compared with the other two methods. The sensitivity and specificity of MR with Sellers' II degrees or more were 0.84 and 0.90 in LA TAC but were 0.42 and 0.90 in the count method.

Atrial Function↗

PubMed1990

Prediction of glycyrrhizin disposition in rat and man with liver failure by a physiologically based pharmacokinetic model.

Two physiologically based pharmacokinetic models A and B incorporating enterohepatic recycling, which succeeded previously in predicting the disposition of glycyrrhizin (GLZ) in normal rats and subjects, were applied to predict GLZ disposition in plasma and tissues of chronically CCl4-intoxicated rats, and serum of humans with hepatitis after i.v. dosing. The prediction by model A with the direct excretion of GLZ from liver into gut lumen gave fairly good agreement with the observed time courses of GLZ concentrations in blood and tissues in the intoxicated rats. The human serum disposition was predicted by model B, to which was added a gallbladder for the excretion from liver into gut lumen to model A by assuming continuous delaying transfer from the gallbladder. An attempt to predict the serum dispositions in five human subjects by considering individual differences in serum free fraction, biliary excretion ratio, and intestinal absorption clearance was successful in model B. Thus, scale-up of the disposition kinetics of GLZ from rat to man with liver failure was successful.

Animals↗

PubMed1990

Prediction of glycyrrhizin disposition in rat and man by a physiologically based pharmacokinetic model.

Three physiologically based pharmacokinetic models A--C, incorporating enterohepatic recycling, were developed to predict glycyrrhizin (GLZ) disposition in rat plasma and tissues, and human serum. Model A, which included fourteen compartments (artery, vein, tissues except brain, and gut lumen) with the assumption of direct excretion of GLZ from the liver into the gut lumen gave fairly good agreement between the observed and predicted disposition profiles in rat, but was unsuitable in man, where elimination is very rapid. Models B and C for man were obtained by adding a gallbladder compartment (drug storage organ) for the excretion from the liver into the gut lumen and by assuming continuous transfer from the storage compartment or instantaneous emptying from it during meal ingestion as the excretion process from the gallbladder into the gut lumen, respectively. The agreement between the observed and predicted serum concentration time-course profiles was better with model C than model B, especially in the terminal elimination phase, where secondary peaks appeared. However, it was thought that the observed serum disposition can be sufficiently well predicted by model B. In conclusion, prediction in rat was successful in all compartments except the brain, which shows a negligible distribution. Scale-up of the disposition kinetics of GLZ from rat to man was also successful.

Animals↗

PubMed1990

Changes in the mixed venous blood oxygen saturation during the acute phase of myocardial infarction and administration of dobutamine.

Clinical significance of the continuous monitoring of mixed venous oxygen saturation (SvO2) by Catheter Oxymetry System was evaluated in 45 patients with acute myocardial infarction (AMI). Patients with AMI were classified into 4 groups according to Forrester's hemodynamic classification. The mean SvO2 value for each group was 70.4 +/- 4.1% for subset I, 54.7 +/- 6.9% for subset II, 55.8 +/- 9.8 for subset III, and 47.0 +/- 8.0% for subset IV. Subsets II, III, and IV showed significantly low values compared to subset I (p less than 0.01). The relationship between PCW and SvO2 level was expressed by the negative regression line y = -0.8x + 73.8 (r = -0.64, p less than 0.01). The curve representing the relationship between CI and SvO2 level was expressed by the equation y = 53.8 logx + 42.7 (r = 0.68, p less than 0.01). The SvO2 level of the 14 patients who showed a significantly low value of 56.9 +/- 8.2% before administration of 5 micrograms/kg/min dobutamin, increased to a mean value of 66.8 +/- 7.9%, as well as the CI after 60 min. However, PCW demonstrated no pronounced changes because of dobutamine administration. Since the SvO2 level highly correlated to the cardiac pumping function in acute phase of myocardial infarction, polygraphic monitoring of SvO2 was found to be a useful index for evaluating changes in the hemodynamics. It was also a very useful measure in evaluating the effects of dobutamin.

Aged↗

PubMed1990

[Observation of oral actions using digital image processing system].

UNLABELLED: A new digital image processing system to observe oral actions is proposed. The system provides analyses of motion pictures along with other physiological signals. The major components are a video tape recorder, a digital image processor, a percept scope, a CCD camera, an A/D converter and a personal computer. Five reference points were marked on the lip and eyeglasses of 9 adult subjects. Lip movements were recorded and analyzed using the system when uttering five vowels and [ka, sa, ta, ha, ra, ma, pa, ba[. RESULTS: 1. Positions of the lip when uttering five vowels were clearly classified. 2. Active articulatory movements of the lip were not recognized when uttering consonants [k, s, t, h, r[. It seemed lip movements were dependent on tongue and mandibular movements. Downward and rearward movements of the upper lip, and upward and forward movements of the lower lip were observed when uttering consonants [m, p, b[.

Humans↗

PubMed1990

Availability of 4'galactosyllactose (O-beta-D-galactopyranosyl-(1----4)-O-beta-D-galactopyranosyl-(1----4)- D-glucopyranose) in rat.

O-beta-D-Galactopyranosyl-(1----4)-O-beta-D-galactopyranosyl-(1----4)-D- glucopyranose (designated as 4'GL) is produced from lactose by Cryptococcus laurentii. The influence of chronic ingestion of 4'GL on body weight gain, organ weight, serum lipids, and liver lipids was investigated in rats. The body weight gains of the 5% and 10% 4'GL-diet groups were higher than that of the control group. Food intake and fecal dry weight were significantly increased (p less than 0.05) by 4'GL feeding. The 4'GL diet produced a significant increase (p less than 0.01) in the wet weight and contents of both the cecum and the colon. However, no significant increase was observed in the weight of the stomach, small intestine, liver, or other organs. The effects of 4'GL on serum and liver lipid levels were not observed in this experiment. The digestion of 4'GL was measured in vitro using the artificial gastric juice, alpha-amylase of human saliva, alpha-amylase of hog pancreas, and mucosa of rat intestine. 4'GL was not hydrolyzed by these enzymes. Long-term ingestion of 4'GL did not cause any induction of 4'GL hydrolyzing enzyme activity in the rat small intestine.

Animals↗