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Biomedical subjects

M Imai

Publications and source records attributed to M Imai.

At least 325 records · Page 18Linked to original sources
PubMed1991

Glands distributed in the lamina propria mucosae of the esophagus in the gecko and Japanese lizard.

In an earlier study, we found compound tubular glands distributed in the lamina propria mucosae of human and fowl esophagus. Subsequently, we discovered bottle-shaped glands in the Japanese lizard and gecko esophagus in the same lamina as that of the human and fowl. Moreover those glands produced equivalent pepsinogen granules. We provide below, a detailed description on the results. 1. Bottle-shaped glands were distributed in the lamina propria mucosae of the Japanese lizard and gecko esophagus. 2. A large number of those glands were distributed in the lower region of the esophagus, but did not exist in the upper and middle regions of the esophagus. 3. The esophageal mucous membrane of the gecko and Japanese lizard were covered with a simple columnar ciliated epithelium, and the same epithelium reacted strongly to PAS and AB (pH 2.5), moderately to AB (pH 0.5) or negatively. 4. PAS-AB (pH 2.5) stain presented a dark blue color or a deep red color or a deep red and dark blue mixed color in one section. 5. The above-mentioned glands contained pepsinogen granules. 6. Those glands do not possess parietal cells.

Animals↗
PubMed1991

[The effect of orthography and imagery on recall of stimulus items which were read aloud].

The purpose of this study was to compare Kanji items with Kana ones in terms of the free recall performance, and to investigate the effect of orthography and imagery on memory. Two experiments were conducted in incidental learning paradigm, in which subjects were instructed to read aloud each stimulus item. In Experiment 1, an immediate recall test was used. Number of correct free recall for low imagery items was larger in Kanji than in Kana, and this result agreed with Yokoyama and Imai (1989). In Experiment 2, 30-s delay was inserted between a reading aloud task and a recall test. The recall performance indicated superiority of Kanji items in high imagery items. These results were interpreted that the recall process was different between in Kanji items and in Kana ones.

Acoustic Stimulation↗
PubMed1991

Selectivity of ion permeability across ascending thin limb of Henle's loop: interaction of Cl- and other halogens with anion transport system.

In hamster ascending thin limb of Henle's loop (ATL) perfused in vitro, we examined halogen selective permeability and effects on Cl- transport. Relative permeabilities for halogens to sodium (PX/PNa) were determined by single salt dilution voltage. (PF/PNA, PCl/PNa, PBr/PNa and PI/PNa were 0.47 +/- 0.09, 3.23 +/- 0.22, 3.23 +/- 0.26, and 0.47 +/- 0.09, respectively. Simultaneous determination of 36Cl and 125I fluxes confirmed that addition of 10(-4) M 5-nitro-2-(3-phenyl-propylamino)-benzoate (NPPB), a Cl- channel blocker, to the bath decreased the flux coefficient for 36Cl (10(-7) cm2/s) from 67.0 +/- 11.7 to 29.5 +/- 7.9 without affecting that for 125I. NPPB also reduced both PCl/PNa and PBr/PNa from 2.67 +/- 0.20 to 0.95 +/- 0.12 and from 2.33 +/- 0.24 to 1.32 +/- 0.12, respectively. Addition of 100 mM Cl- or I- decreased 36Cl flux coefficient from 124.8 +/- 14.3 to 87.7 +/- 13.0 or to 41.0 +/- 11.6 without affecting that for 125I. All other halogens and SCN- also exhibited inhibitory effects on 36Cl flux. These findings support the hypothesis that the putative Cl- channel in the ATL is highly permeable to both Cl- and Br- but less permeable to I-, F-, and SCN-. They suggest that there are at least two functionally distinct components in the process of Cl- transport across the ATL, the binding site and the selective barrier. All halogens may compete against Cl- at the binding site.

Animals↗
PubMed1991

Establishment and characterization of immortalized non-transplantable mouse mammary cell lines cloned from a MMTV-induced tumor cell line cultured for a long duration.

During the culturing of a mouse mammary tumor cell line, MuMT73, maintained in vitro for more than a decade, we found morphological heterogeneity in its cells; some showed contact inhibition in their growth, some formed domes and some grew criss cross and piled up. In trying to clone the cell line to isolate cells showing contact inhibition or dome formation, we were able to establish six clonal cell lines. These six cell lines were categorically divided into three groups according to their phenotypical behavior, Groups A, B and C. Group A (clones 1, 5 and 7) cells had a property of contact inhibition. They induced no tumor when injected into the subcutaneous tissue of the back, nor even when injected into the mammary fat pads or under the kidney capsule of syngenic or nude mice, and therefore were thought to be non-malignant in nature. They were positively stained by anti-keratin antiserum and had mouse mammary tumor viruses (MMTVs). Group B (clone 6) cells grew in a crisscross pattern and piled up, and they induced tumors when injected into the subcutaneous tissue of the back of mice. Group C (clones 3 and 4) cells formed domes in their growth and induced some tumors in the mammary fat pads and under the kidney capsule of KSN nude mice. In Southern blots with MMTV-env probe, numerous exogenous MMTV proviruses were detected in these cell lines. The insertion patterns of these proviruses in cells of non-malignant clonal lines (Group A) resembled those of malignant lines (Group B), except one band (about 26 Kb), but were considerably different from those of intermediate lines (Group C). On the other hand, no difference was detected in Southern blots with int-1 or int-2 probes among the non-malignant, intermediate and malignant clonal cell lines.

Animals↗
PubMed1991

[Recovery of visual field defects in ischemic optic neuropathy and idiopathic optic neuritis].

Fifty-four eyes of 41 patients with optic nerve disease demonstrating acute visual field defects without any traumatic, compressive, or other known etiology were classified into four categories. Those showing poor recovery of visual field defects were ischemic optic neuropathy which was subclassified into either anterior ischemic optic neuropathy (AION) or posterior ischemic optic neuropathy (PION) according to the ophthalmoscopic changes in the optic nerve head. Those showing good recovery of visual field defects were idiopathic optic neuritis which was subclassified into either papillitis or retrobulbar neuritis according to the ophthalmoscopic pathology of the optic disc. Patients with ischemic optic neuropathy were significantly older than those with optic neuritis. All eyes with optic neuritis showed good recovery of vision, whereas those with ischemic optic neuropathy showed varying outcomes of vision. With regard to the pattern of field defect, central or paracentral scotoma was predominant in all but eyes with AION in which altitude defect predominated. Pale swelling of the optic nerve head and angiographic evidence of circulatory disturbance in the optic disc or adjacent choroid were common findings in eyes with AION, whereas such findings were never observed in eyes with papillitis. The amplitude of pattern visual evoked potential was significantly lower in eyes with PION than in those with retrobulbar optic neuritis. Four patients classified as optic neuritis developed into multiple sclerosis in the follow-up study. It was concluded that poor recovery of visual field defect is one of the most convincing evidences for the diagnosis of ischemic optic neuropathy.

Adult↗
PubMed1991

[Enhanced myocardial depression from bupivacaine in diabetic rats].

We examined the direct effects of bupivacaine on the diabetic rat myocardium using an isolated perfused (Langendorff) heart preparation. Rats were made diabetic by injection of streptozotocin (55 mg.kg-1, i. v.). 12 weeks after the administration of streptozotocin, hearts were excised and perfused using Langendorff technique. Following 60 min for equilibration, diabetic hearts from the 12-week animals exhibited significant bradycardia. Bupivacaine 3 mcg.ml-1 did not decrease myocardial contractility in control animals. However, 3 mcg.ml-1 bupivacaine decreased contractility significantly in diabetic animals at nearly all periods. Bupivacaine decreased heart rate and coronary flow significantly and similarly in control and diabetic rats hearts. After pacing at 4 Hz, bupivacaine decreased contractility more in diabetic group than in control group. These results indicate that the presence of a diabetic state appears to enhance the sensitivity of the heart to the myocardial depressant effect of bupivacaine.

Animals↗
PubMed1991

Bilateral enlargement of the aortic valve ring for valve replacement in children. New operative technique.

We report a new technique for the bilateral enlargement of a small aortic anulus in two children by the insertion of a bifurcated teardrop-shaped Dacron fabric lined with a porcine pericardium. Our experience in two children indicates that this technique will permit the insertion of a prosthetic valve that is four sizes larger than that measured with the native anulus intact in children weighing around 15 kg. It entails no risk of distorting the mitral valve, damaging the conduction system, the main coronary arteries or their important trunks, or of leading to left ventricular dysfunction.

Aortic Valve↗
PubMed1991

[Early 123I-IMP SPECT in patients with epilepsy].

Early single photon emission computed tomography (SPECT) using N-isopropyl-p-[123I]iodoamphetamine (123 I-IMP) was performed in seventy-one patients with epilepsy admitted to Kanagawa Rehabilitation Hospital from July 1987 to February 1989; epilepsy and epileptic syndrome 27, encephalitis/encephalopathy 10, clinical Reye syndrome 3, cerebro-vascular disorders 8, sequelae of head trauma 4, cerebral palsy 5, brain anomaly 4, others 10. We classified these cases according to the 1989 criteria of the International League Against Epilepsy, and compared with the findings of the SPECT studies with the EEG and CT. In idiopathic epilepsy, the SPECT findings were within normal limits. Abnormal foci on EEG were not correlated with low uptake areas on SPECT. In the symptomatic epilepsy, especially in the West and Lennox syndromes, SPECT showed a decrease in diffuse cerebral cortical blood flow during ACTH therapy. This was also seen in some cases with normal CT imaging. The results suggest that the hemodynamic pathophysiology of the brain and the indications of therapeutic effectiveness in epilepsy are shown more accurately by SPECT than CT.

Adolescent↗
PubMed1991

[Results of open heart surgery in neonates--comparison between profound hypothermia with circulatory arrest and deep hypothermic bypass].

To investigate factors affecting surgical outcome of open heart surgery in neonates, a retrospective review was carried out on 38 patients operated in the 9 years period from May 1981 to August 1990, in our institution (TAPVR19, TGA7, HLHS7, and others 5). In the former 3 years and 9 month period, 12 patients were operated with the use of profound hypothermia and circulatory arrest (Group I) and in the latest 5 year and 5 month period, continuous deep hypothermic bypass was used in all but for 7 patients with HLHS (Group II). In the group of neonates with TAPVR, operative mortality improved to 7% (1 of 14) in Group II compared to that of 60% (3 of 5) in Group I. CVP and LAP measured immediately after cessation of cardiopulmonary bypass (CPB) were lower in Group II and the value of CPK-MB was significantly lower in Group II. There was a significant negative correlation (r = -0.695, p less than 0.05) between CPB time and urine volume for 72 hours after operation. A significant negative correlation (r = -0.899, p less than 0.01) was also obtained between CPB time and urine volume in the group of 7 neonates with TGA. There was no significant difference in urine volume between patients with TAPVR and TGA despite of significantly longer CPB time in patients with TGA. It is concluded that, 1) improved protection of cardiac and renal function was obtained in neonates operated with the use of continuous deep hypothermic bypass, 2) surgical outcome was influenced by the method of CPB, CPB time and differences in cardiac function ascribed to primary lesions.

Assisted Circulation↗
PubMed1991

[Crossed cerebellar diaschisis demonstrated by SPECT in hemiplegic children].

Crossed cerebellar diaschisis (CCD) in twenty five children with hemiplegia were studied using single photon emission computed tomography (SPECT) with N-isopropyl-p-I-123-iodoamphetamine. Seven of twenty-five patients had cerebral palsy, and the others were impaired by acquired brain injury between ten months and fourteen years of age. CCD was demonstrated in five patients (20%), who were impaired by acquired brain injury after seven years of age. CCD could never be detected in patients with cerebral palsy. Ipsilateral cerebellar diaschisis was also demonstrated in two patients with cerebral palsy and three with early acquired brain injury before three years of age. It is suggested that diaschisis presents itself as a different form in a contralateral and ipsilateral cerebellum before three years of age from a form which presents after seven years of age.

Adolescent↗
PubMed1990

Molecular cloning of a cDNA encoding aldosterone synthase cytochrome P-450 in rat adrenal cortex.

Using an oligonucleotide probe designed on the basis of the N-terminal amino acid sequence of purified rat aldosterone synthase cytochrome P-450 [(1989) J. Biol. Chem. 264, 10935] we have isolated from rat adrenal cDNA library a 2687 base pair cDNA that encodes a protein of 500 amino acid residues. The deduced amino acid sequence contained the regions well conserved among all cytochrome P-450s sequenced to date, and also a portion (residues 25-44) which was identical to the N-terminal peptide sequence of rat aldosterone synthase cytochrome P-450. These results indicate that the cDNA encodes a precursor form of rat aldosterone synthase cytochrome P-450.

Adrenal Cortex↗
PubMed1990

The AT richness and gid transcription determine the left border of the replication origin of the E. coli chromosome.

We have identified novel, cis-acting elements which enhance in vivo the replication activity of plasmids carrying the minimal oriC of Escherichia coli. These are (i) the AT rich sequence ('AT-cluster') which exists immediately left of the 13mer repeats and (ii) the gid transcriptional unit. The 'AT-cluster' was functionally replaced by an unrelated AT rich sequence. This was also the case for the left and middle 13mers; they were substituted by the AT rich fragment from mini-F plasmid. The left 13mer was replaced by the AT rich sequence which did not show the 'reduced helical stability' known as the important character of the 13mer region. In contrast to these results, the right 13mer sequence was strictly required. As to the effect of the transcription from the gid promoter, the minimal oriC was activated only when the transcription was directed away from the left side of it. mioC transcription proceeding toward the oriC had no effect on the activation. Mutations in the DnaA boxes were partially suppressed by gid transcription leaving oriC from the left side. From these results, we propose that the AT richness is a determinant to identify the left border of oriC. It is presumed that gid transcription introduces negative superhelicity at the AT rich region and facilitates DnaA dependent duplex opening.

Adenine↗
PubMed1990

Electrophysiological study of inner medullary collecting duct of hamsters.

The electrophysiological properties of the hamster mid-inner medullary collecting duct (IMCD2) cells were examined in isolated and perfused preparations by intracellular impalement with conventional 1 mol/l KCl microelectrodes and cable analysis. The transmural voltage (VT) was not different from 0 mV, while the basolateral transmembrane voltage (VB) was -81.7 +/- 0.91 mV (n = 221). The transmural resistance (RT) was 109 omega cm2, indicating that the IMCD2 is composed of tight epithelia. The fractional apical membrane resistance (fRA) was 0.98 +/- 0.003 (n = 10). Abrupt changes in the luminal concentration of Na+, K+ or Cl- did not alter the apical membrane voltage (VA) or VT, and neither 2 mmol/l Ba2+ nor 10 mumol/l amiloride in the lumen affected VA and VT. Moreover, pretreatment of hamsters with deoxycorticosterone acetate (5 mg/kg, s.c.) for 10-14 days caused only a very small change in VT in the negative direction. Amiloride in the lumen increased RT and increased the voltage divider ratio very slightly. However, an abrupt increase in K+ concentration in the bath from 5 mmol/l to 50 mmol/l or addition of 2 mmol/l Ba2+ to the bath depolarized the basolateral membrane by 39 mV and 29 mV, respectively. In the presence of 2 mmol/l Ba2+ in the bath, a reduction of HCO3- concentration from 25 mmol/l to 2.5 mmol/l depolarized VB by 20.4 mV. No Cl- conductance was demonstrated in the basolateral membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiloride↗
PubMed1990

Mechanisms of intracellular pH regulation in the hamster inner medullary collecting duct perfused in vitro.

To examine the mechanisms of H+ transport in the mid-inner medullary collecting duct of hamsters, we measured the intracellular pH (pHi) in the in vitro perfused tubules by microscopic fluorometry using 2',7'-bis(carboxyethyl)-carboxyfluorescein (BCECF) as a fluorescent probe. In the basal condition, pHi was 6.74 +/- 0.04 (n = 45) in HCO3(-)-free modified Ringer solution. Either elimination of Na+ from the bath or addition of amiloride (1 mM) to the bath produced a reversible fall in pHi. After acid loading with 25 mM NH4Cl, pHi spontaneously recovered with an initial recovery rate of 0.096 +/- 0.012 (n = 23) pH unit/min. In the absence of ambient Na+, after removal of NH+4, the pHi remained low (5.95 +/- 0.10, n = 8) and showed no signs of recovery. Subsequent restoration of Na+ only in the lumen had no effect on pHi. However, when Na+ in the bath was returned to the control level, pHi recovered completely Amiloride (1 mM) in the bath completely inhibited the Na(-)-dependent pHi recovery. Furthermore, elimination of Na+ from the bath, but not from the lumen, decreased pHi from 6.97 +/- 0.07 to 6.44 +/- 0.05 (n = 12) in the HCO3-/Ringer solution or 6.70 +/- 0.03 to 6.02 +/- 0.5 pH unit/min in the presence of CO2/HCO3-, whereas it did not recover in the absence of CO2/HCO3-.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiloride↗
PubMed1990

Effect of parathyroid hormone on the connecting tubule from the rabbit kidney: biphasic response of transmural voltage.

The effect of parathyroid hormone (PTH) on ion transport was examined by observing transmural (VT) and basolateral membrane voltage (VB) in the in vitro perfused rabbit connecting tubule. Addition of 10 nmol/l PTH to the bath induced a biphasic response of VT, with hyperpolarization followed by depolarization. Chlorophenylthioadenosine cyclic 3',5'-monophosphate mimicked the effect of PTH, which did not change the VB in the connecting tubule cell, but mainly caused changes in the apical membrane voltage. The VT of distal convoluted tubule and the cortical collecting duct were not affected by PTH. Elimination of Na+ from the lumen abolished the PTH-induced VT responses in the connecting tubule. In the presence of 10 mumol/l amiloride, PTH caused an initial hyperpolarization but did not induce the late depolarization. The same was seen in the absence of luminal Ca2+. Either addition of 0.1 mmol/l ouabain to the bath or elimination of bath Na+ completely abolished the PTH-induced VT changes. The presence of 5 mmol/l Ba2+ in the lumen did not affect the response to PTH. These findings indicate that the initial hyperpolarization may be caused by an increase in Na+ influx across the luminal membrane through an amiloride-insensitive Na+ conductive pathway and that the late depolarization may be caused by the decrease in Na+ influx through the amiloride-sensitive Na+ conductive pathway. Luminal Ca2+ is necessary for the late depolarization caused by PTH.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiloride↗
PubMed1990

Mechanism of water transport across the upper portion of the descending thin limb of long-looped nephron of hamsters.

The mechanisms of water transport across the upper portion of the descending limb of long-looped nephron (LDLu) were examined by microperfusion of segments isolated from hamster kidneys. Because of cation permselectivity a streaming voltage was generated when a transmural osmotic gradient was imposed. When 100 mmol/l urea was added to the bath, the streaming voltage was -4.9 +/- 0.4 mV. Addition of 10(-4) mol/l parachloromercuribenzene sulfonate (PCMBS) decreased the voltage to -2.4 +/- 0.7 mV. This effect was associated with changes in osmotic water permeability (Pf, 10(-3) cm/s) from 243 +/- 42 to 47 +/- 15. PCMBS also decreased the transmural diffusional water permeability (Pdw, 10(-3) cm/s) from 9.4 +/- 0.6 to 7.2 +/- 0.6. The inhibitory effect of PCMBS was prevented by pretreatment with dithiothreitol. N-Butanol permeability was measured as an index of cellular resistance for diffusion. Large differences between Pf and Pdw can be explained both by cellular resistance to diffusion and by resistance through a water channel with a single file mechanism. The apparent activation energy for water transport, 13.3 x 10(3) joule/mol (3.16 kcal/mol), was low. These findings are compatible with the hypothesis that a water channel exists in this segment. PCMBS also inhibited the NaCl diffusion voltage, a parameter indicating cation permselectivity, in parallel with suppression of the streaming voltage, suggesting that the water channel is in part associated with cation permselectivity. The possibility that the PCMB-sensitive cation-permselective pathway exists in parallel cannot be ruled out.

1-Butanol↗