Biomedical subjects

M Imai

Publications and source records attributed to M Imai.

At least 19 recordsLinked to original sources

PubMed1992

Transcription in vivo within the replication origin of the Escherichia coli chromosome: a mechanism for activating initiation of replication.

Within the replication origin, oriC, of the Escherichia coli chromosome, novel in vivo transcripts were detected which proceeded rightward and whose production was activated by DnaA protein. In contrast, DnaA protein repressed the previously described ori-L leftward transcription. The former should introduce negative supercoiling, and the latter positive supercoiling, into the 13-mers. The effects of transcription on the initiation of replication were also investigated by making constructs with promoters placed near oriC. Transcription was found to enhance the origin activity only when it was oriented in such a way as to introduce negative supercoiling into the 13-mers. From these results, we propose that transcription within oriC regulates replication initiation by altering the topology of the 13-mer region.

Base Sequence↗

PubMed1992

Systemic atrioventricular valve replacement in an infant with corrected transposition of the great arteries.

A 3-month-old infant with corrected transposition of the great arteries and severe systemic atrioventricular valve regurgitation due to "Ebstein-like anomaly" is reported. Through a right thoracotomy and longitudinal left atrial incision, a 19-mm St. Jude Medical valve was implanted into the annulus without removing the native valve. He is doing well 7 months after operation.

Ebstein Anomaly↗

PubMed1992

User and manufacturer's requirements for IMAC standardization in Japan.

Many radiologists and radiological technologists understand that Picture Archiving and Communication Systems (PACS) are useful not only for image management but also for improving the quality of patient care. However, such systems have not yet been widely installed in hospitals. In order to determine why radiologists have not installed a PACS in their hospitals, we carried out a written survey of 400 Japanese hospitals asking them to describe the current image management activities, the problems inherent in PACS and the problems related to standardization. 216 hospitals responded, and the following suggestions were compiled concerning possible improvements to PACS. (1) PACS benefit needs to be improved with respect to patient care. (2) The cost of PACS should be reduced. (3) The system should be easier to operate and should save time. (4) Standardization is needed to allow simplified, cost-effective networking. We also carried out a written survey of 25 PACS and related equipment manufacturers asking them to describe the opinions inherent in current PACs and the problems related to standardization. Ten manufacturers responded, and the various suggestions were compiled concerning possible improvements to the PAC system.

Japan↗

PubMed1992

Severe type Hunter's syndrome. Polysomnographic and neuropathological study.

The clinico-pathological and polysomnographical findings of an adult male patient with severe type of Hunter's syndrome are presented. He died of respiratory failure aged 19, which was much older than the average in this disease. Mucopolysaccharidosis was suspected at the age of one year, and diagnosed by leucocyte enzyme assay at 4 years of age. Mental and physical activity gradually deteriorated until his death. He often showed central type sleep apnea during the sleep stage 2, in addition to common obstructive apnea in Hunter's syndrome. The autopsy showed marked fibrous thickening of the endocardium and valves, enlargement of the liver and spleen, dilatation of the lateral ventricles and diffuse atrophy of the brain. Histologically, diffuse cytoplasmic vacuolations were found in fibroblast-like cells in the thickened endocardium and vascular walls, in Kupffer cells, and in many neurons of the central and peripheral nervous systems. Most neuronal inclusions were considered to be a ganglioside, and in other cells to be a mucopolysaccharide, by their ultrastructure. Massive accumulation of ganglioside in the neurons in the respiratory center might be reflected on central type sleep apnea.

Adult↗

PubMed1992

Effect of dietary sodium restriction on mRNA for aldosterone synthase cytochrome P-450 in rat adrenals.

Changes in the level of mRNA for aldosterone synthase cytochrome P-450 (cytochrome P-450aldo) in rats on dietary sodium restriction were studied by means of Northern and slot blot hybridization using an oligonucleotide probe that allowed differentiation of the message for this enzyme from that for cytochrome P-450(11)beta. These two enzymes have been shown to be highly homologous with each other, exhibiting 88% homology in their nucleotide sequences in the coding region. Upon sodium restriction for 2 weeks, cytochrome P-450aldo mRNA in rat adrenals increased 7-fold, whereas the cytochrome P-450(11) beta mRNA level in the same adrenals did not change significantly. The increase in cytochrome P-450aldo mRNA paralleled that in cytochrome P-450aldo protein, as analyzed by immunoblot technique. These results, together with our previous finding that angiotensin II induced cytochrome P-450aldo in rat adrenocortex [Shibata, H., Ogishima, T., Mitani, F., Suzuki, H., Murakami, M., Saruta, T., & Ishimura, Y. (1991) Endocrinology 128, 2534-2539], suggest that the production of cytochrome P-450aldo is regulated by angiotensin II at the pretranslational level, most likely at the transcriptional level.

Adrenal Glands↗

PubMed1992

Reaction of sevoflurane and its degradation products with soda lime. Toxicity of the byproducts.

Sevoflurane previously has been reported to undergo extensive degradation in the presence of soda lime. To more completely characterize the extent and significnce of this reaction, we studied degradation of sevoflurane with and without soda lime, as well as the toxicity and mutagenicity of the degradation products. Two degradation products detected were CF2 = C(CF3)OCH2F (compound A) and CH3OCF2CH(CF3)OCH2F (compound B). During circulation of 1%, 2%, and 3% sevoflurance in a closed anesthesia circuit for 8 h, peak concentrations of compound A were 13.3 +/- 0.27, 30.2 +/- 0.10, and 42.1 +/- 1.07 ppm at 2 h, respectively. The concentrations of compound B did not exceed 2 ppm. The temperature of the soda lime was 43.3 +/- 2.8 degrees C at 1 h and increased gradually to 47.9 +/- 1.5 degrees C after 8 h. In closed flasks with soda lime, the magnitude of the decrease in sevoflurance concentrations (3%) and of the increase in compound A concentrations was temperature dependent. The peak concentrations of compound A at 23 degrees C, 37 degrees C, and 54 degrees C were 32.8 +/- 6.8 at 2 h, 46.6 +/- 1.0 at 0.5 h, and 78.5 +/- 2.3 ppm at 0.5 h, respectively. The LC50 (50% lethal concentration) of compound A in Wistar rats was 1,090 ppm in males and 1,050 ppm in females exposed for 1 h. The LC50 was 420 ppm in males and 400 ppm in females exposed for 3 h. The chronic toxicity of compound A in Wistar rats was studied by exposing rats 24 times, for 3 h each, to initial concentrations of 30, 60, or 120 ppm in a ventilated chamber. At all concentrations, there were no apparent effects other than a loss of body weight in females (120 ppm) on the final day (P < 0.01). Compound A did not induce mutation on the reverse (Ames) test at less than 2,500 micrograms/dish (culture medium 2.7 ml) with activation by S-9 mixture, and below 1,250 micrograms/dish (culture medium 2.7 ml) without activation, in four strains of S. typhimurium and in 1 strain of E. coli. Exposure of fibroblasts to 7,500 ppm of compound A for 1 h, compound A did not induce structural change. In a study of acute toxicity of compound B, there was no toxicity in Wistar rats after 3 h of exposure at 2,400 ppm. The reverse (Ames) test for compound B was negative at 625-1,250 micrograms/dish.(ABSTRACT TRUNCATED AT 400 WORDS)

Absorption↗

PubMed1992

Analysis of spinal cord evoked potential and locomotor function during acute spinal cord compression in cats.

The aim of this study was to investigate whether or not conductive spinal cord evoked potentials and spinal cord function change correspondingly with each other. The relationship between conductive spinal cord evoked potentials and locomotor function during acute spinal cord compression in animals was investigated. In decerebrate cats, controlled locomotion can be induced by electrical stimuli in the mesencephalic locomotor region. Conductive spinal cord evoked potentials were recorded at the L3 level of the spinal cord and stimuli were given at the T4 segment. The locomotor function was evaluated through electromyograms of the hind limbs. By compressing the spinal cord at L1, both the conductive spinal cord evoked potentials and the locomotor function gradually decreased. When the first negative potential amplitude of conductive spinal cord evoked potentials was decreased to half the level found in normal cats, locomotor function was injured irreversibly. These results showed that changes in the conductive spinal cord evoked potentials were related to changes in locomotor function. The 50% level of the first negative potential amplitude was considered to be the critical level at which irreversible spinal cord paralysis occurred in the cats.

Acute Disease↗

PubMed1992

Mechanism of PGE2-induced cell swelling in distal nephron segments.

The effects of prostaglandin (PG) E2 on cell swelling were studied in isolated perfused tubules of rabbit kidney. PGE2 (1 microM) added to the bath induced cell swelling by 13.4, 7.2, and 9.6% in the connecting tubule, distal convoluted tubule, and cortical collecting duct, respectively, but it had no effect on the proximal convoluted tubule and cortical thick ascending limb. The response was dose dependent in the range of 1 nM to 1 microM. PGI2 exerted a similar effect, but PGF2 alpha had no effect. The swelling was completely blocked by basolateral Na+ removal and was attenuated by bilateral Cl- removal, suggesting that the swelling was mediated by basolateral Na+ entry in association with Cl- entry. In all segments except proximal tubule, PGE2 caused an initial transient peak followed by a sustained increase in intracellular Ca2+. Intracellular Ca2+ chelation or inhibition of Ca2+ release from intracellular stores abolished the PGE2-induced cell swelling, but extracellular Ca2+ removal did not. An inhibitor of the Na(+)-Ca2+ exchanger (3',4'-dichlorobenzamil, 100 microM) in the bath completely inhibited PGE2-induced cell swelling. Neither furosemide (1 mM) nor amiloride (1 mM) added to bath abolished the response, indicating that neither Na(+)-K(+)-2Cl- cotransport nor Na(+)-H+ exchange is involved in the action of PGE2. The swelling response to PGE2 was observed even in the presence of ouabain, indicating that the effect of PGE2 is independent of Na(+)-K(+)-adenosinetriphosphatase inhibition. Nicardipine added to bath partially inhibited the swelling response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Interaction of Cl- and other halogens with Cl- transport systems in rabbit cortical collecting duct.

We have reported that in the rabbit cortical collecting duct (CCD) we can identify electrophysiologically three distinct cell types; the collecting duct (CD) cell and the alpha- and beta-intercalated (IC) cell. To further characterize the Cl- transport properties of each cell type, we examined the interaction between Cl- and other halogens or SCN- in the isolated and perfused CCD by intracellular microelectrode impalement. The rapid depolarization of the basolateral membrane potential (VB) caused by replacement of bath Cl- with each anion revealed that the sequences of apparent halogen selectivity for the basolateral Cl- conductance were similar in all three cell types. The ranking of Cl- > Br- > F- > I- corresponds to the sequence 5 of Eisenman's series, indicating "strong" interaction of the anions with the selectivity site. The basolateral Cl- conductance of these three cell types may share common characteristics, although I- permeability is less in IC cells than in CD cells. Hyperpolarization of the basolateral membrane of the beta-IC cell upon reduction of luminal Cl- reflects alterations in either Cl- entry across the apical membrane, or Cl- exit across the basolateral membrane, or both. Luminal Cl- replacement with each anion showed that the sequence of the hyperpolarization of the basolateral membrane was I- >> cyclamate = SCN- > F- > Br-, suggesting that I-inhibits either apical Cl- entry or basolateral Cl- exit. On the other hand, in the CD cell reduction of the perfusate Cl- by replacement with each anion caused the basolateral membrane to hyperpolarize with a different ranking: cyclamate = F- > I- = SCN- > Br-.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Simulation of the profile of water, NaCl, and urea transport in the countercurrent multiplication system between thin ascending limb and inner medullary collecting duct.

We simulated the profiles of water, NaCl, and urea transport in the countercurrent multiplication system between thin ascending limb (TAL) and inner medullary collecting duct (IMCD) by a mathematical model consisting of three compartments (TAL, IMCD, and CNW [capillary network]), using phenomenological coefficients for hamsters. They are separated by two membranes with distinct permeability properties. The primary driving force which generates "single effect" has a lower reflection coefficient for urea than for NaCl in IMCD. The difference in urea and NaCl concentrations between CNW and IMCD provides an effective osmotic driving force which is favorable for water absorption from IMCD without physicochemical osmotic gradient. The entry of water in the CNW reduces the concentration in CNW and generates the concentration gradients which are favorable for these solutes to diffuse out of TAL. Thus, the fluid in IMCD is concentrated and that in TAL is diluted. The results of simulation showed that the concentration gradients were generated along the medullary axis, resulting in excretion of hypertonic urine. In addition, we examined effects of changes in phenomenological coefficients of IMCD on this concentrating system. Decreases in permeability and in reflection coefficient for urea and increase in hydraulic conductivity increased the osmotic gradients along each compartment.

Body Water↗

PubMed1992

Family of a patient with serum cholinesterase deficiency.

A-39-year-old man was admitted to our hospital because of a markedly decreased level of serum cholinesterase found incidentally by a blood test. Detailed examination did not reveal severe liver disease, malignant tumor, infection or organophosphate compound poisoning. Investigation of three generations of his family revealed two homozygous and five heterozygous family members with the cholinesterase deficiency gene E1s indicating familial serum cholinesterase deficiency.

Adult↗

PubMed1992

Histological and histochemical investigations on Japanese lizard esophagus.

The authors previously investigated the bottle-shaped glands distributed in the lamina propria mucosae of the Japanese lizard and gecko. We made two sets of sections of the Japanese lizard at that time. The numerical values of the physical dimensions of the two individuals were as given table 1, showing that No. 2 was slightly smaller. Moreover we found very unusual tissue in the lower portion of the esophagus of No. 2. Therefore we excluded this individual from the preceding investigations. However, we made various observations, and the results of these investigations are as follows. 1. The lumen of the upper portion of the esophagus has no fold. However, the middle and lower portions formed very complicated folds. Therefore, the lumen was remarkably narrow. 2. The epithelium of the esophageal mucous membrane consisted of simple columnar cells and throughout each part, reacted strongly to PAS and moderately to AB (pH 2.5 and 0.5). It presented a dark blue (R18-B13 of Blue-Purple-Red) color in response to PAS-AB (pH 2.5) and contained no pepsinogen granules. The esophageal upper portion of small individuals only exhibited the PAS reaction in this investigation. 3. A number of bottle-shaped glands were distributed in the lamina propria mucosae of the lower portion of the esophagus of each material. The glandular cells in the basal portion were most differentiated and contained a great number of pepsinogen granules. 4. The above-mentioned glands were extremely simple and glands of this type could not be found in textbooks and theses. Accordingly, we previously described them with the tentative name of shimple branched tubular glands, but subsequently found this to be erroneous. We assume that these glands are esophageal gastric glands. 5. Compound tubular glands are formed in the lamina propria mucosae of the human esophagus, but do not exist in the Japanese macaque, crab-eating monkey, horse, cow, swine, dog, cat, rabbit, mouse and rat. Dellmann-Brown also described the absence of such glands in the esophagus of the horse, swine, cow, goat, sheep, dog and cat. 6. We subsequently found compound tubular glands distributed in the lamina propria mucosae of the fowl, goose and wild duck esophagus. They similarly secreted pepsinogen granules. 7. We assume that these glands of the Japanese lizard and gecko have a phylogenic relation with the glands in the bird. The pepsinogen-granule-secreting cells in the snake do not extend into the lamina propria mucosae.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1992

[Low reactive-level laser therapy near the stellate ganglion for postherpetic facial neuralgia].

Low reactive-level laser therapy near the stellate ganglion was given for a 68-year-old female with postherpetic neuralgia, suffering from burning pain in the right forehead for 11 years. Stellate ganglion block and supraorbital nerve block with oral medication were not effective to relieve this pain. The laser irradiation induced warm sensation in her face followed by an excellent pain relief. Thermograms illustrated a remarkable increase from 30.6 degrees C to 31.5 degrees C in temperature of her right face. The irradiation near the right carotid artery also had the similar effect. The results imply that the irradiation with low reactive-level laser of the stellate ganglion and/or the carotid artery increases a facial blood flow and relieves facial neuralgia.

Aged↗

PubMed1992

[A clinical course and autopsy results of an 8-year-old severely handicapped girl with marked periventricular leukomalacia].

We reported a clinical course and autopsy results of an 8-year-old severely handicapped girl with marked periventricular leukomalacia. She was well until 3 days prior to first admission in local hospital. Two days prior to admission, she began to vomit. Twelve hours later, she was noted to be lethargic and developed malaise with frequent vomiting. At physical examination on admission, she had frequent fits and her posture was decerebrate rigidity. Consciousness disturbance continued for two weeks. Thereafter, she became severely handicapped with spastic quadriplegia, mental retardation and intractable epilepsy. She was transferred to our hospital one month later. We cared her totally and carefully with our rehabilitation staff, but during her course several rare happening occurred; she suffered from subdural hemorrhage due to hypocupremia and received an operation for the release of contracture of her hips. She died of acute cardio-respiratory failure at 8 years and 5 months of age. Her autopsy findings were characteristic of the damage to an immature brain during development; cactus formation of cerebellar cortex and periventricular leukomalacia.

Acute Disease↗

PubMed1992

Replenishment of brain adenosine triphosphate content by morphinan-type N-methyl-D-asparatate receptor antagonists, dextrorphan and dextromethorphan through the activation of adenylate kinase.

The in vitro effects of four N-methyl-D-aspartate (NMDA) receptor antagonists, dextrorphan, (DX, CAS 125-73-5), dextromethorphan, (DM, CAS 125-71-3), dizocilpine (CAS 77086-21-6) and (+/-) 2-amino-7-phosphonoheptanoate (AP-7, CAS 85797-13-3) on rat brain adenylate kinase (AK) have been studied. DM was the most active of the four compounds in increasing rat brain AK activity. DX was slightly less active than DM, while the most potent NMDA antagonist, dizocilpine was somewhat weaker than the above two morphinan analogs (DX and DM). For AP-7, the AK activity was unchanged. The results may indicate that a causal relation cannot be made between the activation of the AK by these compounds and their ability to act as NMDA antagonists. When DX was added, the Km and Vmax values of the enzyme for ADP as a substrate decreased and increased, respectively, possibly reflecting an affinity change for the enzyme-substrate interaction by DX. The observed increase in the AK activity by the morphinan-type NMDA antagonists in vitro might result in their preserving effects on cerebral neuron integrity under the conditions where cerebral energy metabolism is disturbed. This assumption was at least partly confirmed in in vivo tests in which DX, unlike dizocilpine, increased ATP content of the brain in mice under the influence of hypoxia exerted by i.v. injection of KCN.

2-Amino-5-phosphonovalerate↗

PubMed1992

[Long-term results of the Blalock-Taussig shunts].

One-hundred and thirty-six patients received the classical Blalock-Taussig shunts between 1980 and 1990. Their age range at operation was 4 days to 12.8 years and their median age was 13 months. The operative mortality rate was 0.7% (1/136). The survivors were followed up from 1 month to 11.5 years, 5.4 years in average. Twenty-five patients required another shunt and the mean interval to that procedure was 2.4 years (modified Blalock-Taussig 23, classical Blalock-Taussig 2, Glenn 1, internal mammary artery-pulmonary artery shunt 1). Forty-five patients received corrective operations, there were four operative deaths (Fontan 2, Rastelli 2). There were 15 late deaths of which three deaths were not cardiogenic. One year after operation, 91.0% of patients remained in well-palliated condition. At three years after operation, 76.4% of patients continued to be in well-palliated condition. There were twelve neonates in this series. Their age range was 4 to 26 days and their median age was 13 days. There was no operative death. Five patients required second shunt. There were two late deaths. At present, six patients continue to be in well-palliated condition 8 months to 9 years after first operation. Angiographic findings showed the stenotic change of the vascular anastomoses in 49.3% (35/71) of patients. This study suggests that polydioxanone suture (PDS) will be useful for the growth of the anastomoses in Blalock-Taussig operation.

Anastomosis, Surgical↗

PubMed1992

[A case of sarcoidosis with primary acute pulmonary cavitation].

A 23-year-old man was admitted to our hospital on June 24, 1991, because of worsening chest X-ray findings of sarcoidosis. In August 1990, he was referred to our outpatient office, because of BHL and nodular lesions on chest X-ray film performed at his company 4 months earlier. At that time, serum ACE was elevated to 34.0 IU/l, and Ga scintigraphy showed abnormal uptake in bilateral lacrimal and salivary glands, mediastinal and hilar lymph nodes, and in the lung fields. TBLB specimen showed noncaseating epithelioid granuloma with giant cells and negative stains for acid-fast bacilli. Although it was planned to follow this patient without medication, he did not return to our outpatient department. In June 1991, because of worsening of lesions in the lung at annual checkup at his company, he was referred and admitted for steroid therapy. Chest X-ray film on admission showed BHL, multiple nodular lesions in both lung fields, and bullous change in the left upper lobe. Chest CT on admission showed three cavitating lesions within preexisting nodules. PPD skin test was negative, and sputum smears and cultures were repeatedly negative for pyogenic bacteria and acid-fast bacilli. Therapy was initiated with prednisolone 30 mg daily. Four months later, there was marked resolution of BHL and nodular lesions, and the cavitating lesions were no longer visible on chest X-ray film. From the clinical and radiological observations, it is concluded that the cavitating lesions in the present case were primary acute pulmonary cavitation in sarcoidosis, distinct from infection, bullae, or cystic bronchiectasis which are seen in the chronic and fibrotic stages of sarcoidosis.

Adult↗

PubMed1992

[Measurement of intracellular pH].

Since various cellular processes depend on changes in pH, the regulation of intracellular pH (pHi) is important both for the individual cell and for the organism. The mechanisms of the regulation of pHi can be investigated by monitoring pHi. In this report, we discuss the four major techniques available for measuring pHi, which are 1) Distribution of weak acids and bases, 2) pH-sensitive microelectrodes, 3) pH-sensitive dyes, and 4) Nuclear magnetic resonance. Among four techniques, the advantage of the microelectrode approach is that it can monitor membrane potential at the same time and be applied to a single cell. The dye technique is a relative new developing technique, which has lots of advantages. It is easy to use, and is capable of monitoring rapid pHi changes, and being applied to a smaller cell, or a single cell.

Acid-Base Equilibrium↗