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Biomedical subjects

N Takagi

Publications and source records attributed to N Takagi.

At least 145 records · Page 8Linked to original sources

Leaching and cytotoxicity of formaldehyde and methyl methacrylate from acrylic resin denture base materials.

Acrylic resin dentures have the potential to elicit irritation, inflammation, and an allergic response of the oral mucosa. Studies of substances leachable from acrylic resins, their cytotoxicity to cultured cells, and means of reducing their leaching were systematically conducted. Under in vivo and in vitro conditions, formaldehyde and methyl methacrylate were significantly leached into human saliva and saliva-substitute buffer, especially from autopolymerized resins. Both leachable substances showed cytotoxic potentials in the range of their leaching concentrations. Formaldehyde was cytotoxic at lower concentrations than methyl methacrylate. Preleaching in water reduced subsequent leaching of both formaldehyde and methyl methacrylate, and the amount of reduction depended on an increase in the preleaching temperatures. Immersion of acrylic resin dentures in hot water (50 degrees C) before insertion is recommended, especially for autopolymerized resins used either for rebasing or as denture base materials, to minimize the risk of adverse reactions in patients who wear acrylic resin dentures.

Cell Count↗

DNA fingerprint analysis of Dahl-Iwai salt-sensitive rats (S) and salt-resistant rats (R).

Using DNA fingerprint analyses, extensive molecular heterogeneity has been found between spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY), suggesting a doubtful value of simply comparing these rats in the study of the pathogenesis of genetic hypertension. Therefore, we evaluated the genetic similarity between Dahl salt-sensitive and salt-resistant rats newly inbred by Dr.Iwai (Dahl-Iwai S and R rats), by use of DNA fingerprint analysis. Fingerprint patterns were generated by probing Hinf I- or Alu I-digested DNA with an oligonucleotide corresponded to the tandem repeat sequence of the human myoglobin 33.6 minisatellite. These fingerprint patterns were same within each strain. S and R rts shared 82 percent of the bands in Hinf I-digested DNA and 93 percent of those in Alu I-digested DNA. Although Dahl-Iwai S and R rats are more closely related than SHR and WKY rats, multiple genetic differences still exist between these Dahl strains.

Animals↗

Effects of low sodium ouabain and amiloride on chick myocardial contraction.

1. Effects of Ca2+, low Na+, ouabain and amiloride on contractile force were examined in myocardial preparations from embryonic and hatched chicks. Measurement of contractile force was performed in an organ bath with whole hearts for the young embryo (5-6 days old) and with isolated strips from the right ventricles for the old embryos (16-18-day-old), hatched chicks (within 24 hr after hatching) and 1-week-old chicks. 2. The maximum increase in contractile force above the basal value at each age was determined by increasing extracellular Ca2+, which was smaller in young embryonic hearts than in older ones. 3. Decreasing the Na+ concentration to half of the normal value increased the contractile force in all ages examined: the increase in contractile force expressed as a percentage of the maximum increase at each age was significantly larger in young embryonic hearts than in older ones. 4. Ouabain produced increases in contractile forces at all ages examined; the effective concentration was lower in young embryonic hearts than in older hearts. 5. Amiloride prolonged the relaxation phase of contraction at all ages examined; the degree of prolongation was larger in young embryonic hearts than in older ones. 6. The present results suggest that, in the chick myocardium, the relative role of Na(+)-Ca2+ exchange in relaxation decreases during embryonic development, which may reflect the concurrent increase in sarcoplasmic reticulum function [Tanaka, Takagi and Shigenobu (1993) J. Dev. Physiol. 19, 235-240.

Amiloride↗

Determination of tetrahydro-beta-carbolines in urine by high-performance liquid chromatography with suppression of artefact formation.

A high-performance liquid chromatographic method has been developed for the determination of urinary tetrahydro-beta-carbolines. When standing tryptamine with formaldehyde and acetaldehyde under extraction conditions, the significant amounts of artefact 1,2,3,4-tetrahydro-beta-carboline (TBC) and 1-methyl-1,2,3,4-tetrahydro-beta-carboline (MTBC) were formed in a short time. Urine samples added with 2-ethyl-1,2,3,4-tetrahydro-beta-carboline (an internal standard) were treated with fluorescamine, and then with glycine, followed by serial solvent extractions. Such a pretreatment using two-step reactions removed a precursor (trypamine) by extracting its fluorescamine derivative, and enhanced the detection response by consuming excess fluorescamine. It solved the analytical problem that artefact TBC and MTBC are formed during analysis. Reversed-phase ion-pair chromatography using a C8-column and trifluoroacetic acid as a counter ion completed a base-line separation of three analytes within 10 min. The calibration graphs showed a good linearity in the range 0.1-50.0 ng ml-1 of urine samples spiked with standard TBC and MTBC. In the spike experiment, the recovery and relative standard deviation were almost 100% and less than 3.0%, respectively, for both TBC and MTBC. The proposed method enables the determination of the genuine urinary concentrations of TBC and MTBC without involving their artefacts.

Acetaldehyde↗

Reconstruction of stenotic external auditory canal with a postauricular chondrocutaneous flap.

A case of stenosis of the external auditory canal secondary to a burn injury was reconstructed with a chondrocutaneous postauricular flap. Advantages of this technique include the use of a single flap to reconstruct the whole circumference of the canal, the fact that a chondrocutaneous flap is more likely to prevent restenosis than a skin flap alone, and the fact that reconstruction with an axial-pattern flap is more reliable than reconstruction with a random-pattern flap.

Burns↗

Effects of naftidrofuryl oxalate on microsphere embolism-induced decrease in regional blood flow of rat brain.

1. The purpose of the present study was to determine whether naftidrofuryl oxalate (naftidrofuryl), a vasodilator, is capable of improving brain regional blood flow of animals in sustained ischaemia. 2. Cerebral ischaemia was induced by injecting 900 microspheres (48 microns in diameter) into the right internal carotid artery of rats. Cerebral blood flow of brain regions was measured by a hydrogen clearance method on the 3rd, 7th and 28th days after the onset of ischaemia. Ischaemic animals were treated with naftidrofuryl, 15 mg kg-1 day-1 i.p., from the first to 28th day. 3. Microsphere-embolism caused a sustained decrease in cortical and striatal blood flow over a period of 28 days, whereas hippocampal blood flow was decreased on the 3rd day but not on the 7th or 28th day. On the 3rd day, the striatal and hippocampal but not cortical blood flow of naftidrofuryl-treated, microsphere-embolized rats was higher than untreated rats. On the 7th and 28th days, the cortical and striatal blood flow of the treated and untreated animals did not differ. 4. Brain slices from microsphere-embolized rats contained areas, which were not stained with triphenyltetrazolium chloride (TTC), to a similar degree on the 3rd, 7th and 28th days, indicating the genesis of cerebral infarction. TTC-unstained areas of microsphere-embolized rats that had received naftidrofuryl treatment were smaller than those of untreated rats on the 3rd and 7th days, but not on the 28th day. 5. The results suggest that naftidrofuryl improves cerebral circulation impaired by microsphere-induced ischaemia and this higher level of cerebral blood flow of the treated animal may account for the delayed development of cerebral infarction.

Animals↗

Slow hemodialysis performed during the day in managing renal failure in critically ill patients.

Slow hemodialysis (HD) was performed for 10 h during the day in 11 critically ill patients with renal failure. The dialysis method was a modification of the pump-driven continuous venovenous HD. A nonsterile bicarbonate-containing hemodialysate was passed into the EVAL membrane dialyzer at a flow rate of 30 ml/min. No patient developed further hemodynamic instability during the treatment. The serum urea level was maintained below 20 mmol/l within 4 days of initiating the treatment. It allowed the patients to rest without interruption at night. This method was safely conducted by general nursing staff under the supervision of nephrologists on duty during the day. This schedule offers an approach to renal replacement therapy for hemodynamically unstable patients without any potential problem in the extracorporeal circulation at night.

Acute Kidney Injury↗

Molecular mechanism of adipogenic activation of the angiotensinogen gene.

Angiotensinogen gene expression is controlled in a tissue- and development-specific manner. Interestingly, the angiotensinogen gene is abundantly expressed in adipose tissues other than the liver, where it is mainly produced. We investigated the molecular mechanism of angiotensinogen gene expression in a 3T3-L1 preadipocyte-adipocyte system. Although angiotensinogen mRNA was barely detectable in preadipocytes, its levels increased significantly during differentiation. As a whole, the pattern of the change in transcriptional activity of the angiotensinogen promoter was similar to that of the angiotensinogen mRNA levels during adipogenic differentiation, indicating that the activation of the angiotensinogen promoter might be involved in the adipogenic differentiation-coupled gene expression. The proximal promoter region, from -96 to +22 of the transcriptional start site, was sufficient to confer adipogenic activation, and the proximal element from -96 to -52 of the transcriptional start site was necessary for this promoter stimulation. DNA-protein binding experiments showed that this proximal element specifically bound to a nuclear factor induced by adipogenic differentiation. These results suggest that the proximal promoter element from -96 to -52 plays a role in adipogenic activation of the angiotensinogen promoter.

3T3 Cells↗

Hyperresponsiveness of cardiac muscles to histamine in reserpine-treated guinea pigs.

The hyperresponsiveness of cardiac tissue to histamine following treatment with reserpine was pharmacologically characterized. Guinea pig hearts were isolated 24 hours after intraperitoneal administration of 5 mg/kg reserpine. This treatment resulted in a complete depletion of tissue norepinephrine. Reserpine treatment potentiated the positive inotropic response of isolated perfused hearts to histamine at doses ranging from 0.3 to 3 micrograms (23 to 57% increase for reserpine-treated animals vs. 14 to 32% increase for control animals). Isolated left ventricular papillary muscle of reserpine-treated guinea pig hearts also showed hyperresponsiveness to histamine at concentrations of 0.1 microM or greater. The hyperresponsiveness of the papillary muscle contraction of the reserpine-treated animals to histamine was abolished in the presence of 1 microM cimetidine, but not attenuated in the presence of 1 microM diphenhydramine. This hyperresponsiveness was not modified by 1 microM bunazosin or 1 microM propranolol. The results suggest that H2-receptor mediated action plays a role in the hyperresponsiveness of cardiac muscles to histamine.

Animals↗

Anti-Candida activity of synthetic hydroxychalcones.

The antifungal activity of different synthetic hydroxychalcones was determined against Candida species. It was revealed that the presence of hydroxyl groups at C-2, C-4, and C-2' in chalcone was essential to inhibit Candida growth. Among the chalcone derivatives examined, 2,4,2'-trihydroxy-5'-methylchalcone showed the most intensive anti-Candida activity, suggesting that it could be a potential therapeutic agent for candidosis.

Antifungal Agents↗

Pharmacokinetic profiles of intravenous imipenem/cilastatin during slow hemodialysis in critically ill patients.

The pharmacokinetics of imipenem/cilastatin were determined in 7 critically ill patients undergoing slow hemodialysis (HD). All patients were anuric. Following intravenous administration of 500 mg of imipenem/cilastatin, concentrations of the drugs in the serum and dialysate were monitored during slow HD. The elimination phase half-life of imipenem was 3.1 +/- 0.3 h and that of cilastatin was 9.7 +/- 1.2 h. The total body clearance of imipenem and cilastatin was 84.0 +/- 7.2 and 32.2 +/- 2.4 ml/min, respectively. Clearance of imipenem and cilastatin during slow HD was 24.3 +/- 2.4 and 54.3 +/- 3.1%, respectively, of total body clearance. After the 10.5-h session of slow HD, serum concentrations of imipenem and cilastatin were 2.3 +/- 0.4 and 16.0 +/- 1.2 mg/l, respectively. It appears that at least 500 mg of imipenem may be needed as a supplemental dose after a session of slow HD or the application interval should be shortened to maintain a therapeutic concentration.

Aged↗

[A case of Klippel-Trenaunay-Weber syndrome associated with intracranial multiple angiomas].

A case of Klippel-Trenaunay-Weber syndrome associated with multiple intracranial angiomas was reported. Intracranial angiomas with Klippel-Trenaunay-Weber syndrome is very rare. Only 4 cases are known to this day. A 24-year-old man fell at his workplace and suffered a head injury. He was admitted to our hospital. Neurological examination revealed no abnormality. However, physiological examination demonstrated hyperplasia and cutaneous hemangiomas of left lower leg, malformation of the left eyelid and clouding of the left cornea. CT showed left hemispheric atrophy and subdural effusion. MRI demonstrated multiple flow voids at the left cerebellar hemisphere and at pons. Cerebral angiogram demonstrated left cerebellar AVM and pontine angioma. Feeding arteries of the AVM were left superior cerebellar artery and left posterior inferior cerebellar artery. Those of the pontine angioma could not be identified. No spinal angiomas were revealed. While spinal angiomas associated with this syndrome are known, association of intracranial lesions are rare. Reported anomalies are angiomas, hemi-hypertrophy of skull and brain, carotid occlusion, megadolicoanomaly of the basilar artery, meningioma and glioma. Our case report with cerebral angiomas is the first one in Japan. We postulate that anomaly of our case originated at the Streeter's 2nd-3rd stage or that multiple anomalies occurred. We emphasize that intracranial, spinal or visceral angiomas, which can be fatal if it bleeds, should be routinely examined in Klippel-Trenaunay-Weber syndrome.

Adult↗

Clinical features of end-stage renal failure in patients with essential hypertension.

The development and progress of renal deterioration in patients with essential hypertension administered antihypertensive therapy remain unclear. In this retrospective analysis, we divided 25 essential hypertension patients who eventually required hemodialysis (HD) from 1981 to 1990, into those with malignant essential hypertension (MEH) (N = 9) and those with benign essential hypertension (BEH) (N = 16), and analyzed the clinical features, the rate of renal deterioration, and outcome in each group. The patients with MEH were significantly younger, and had a shorter duration of hypertension than those with BEH. There were no significant differences between the two groups in urinary volume, cardiothoracic ratio, hematological findings or blood chemistry at the initiation of HD. However, blood pressure in the patients with MEH was significantly higher than that in the patients with BEH at that time despite antihypertensive treatment. There was also no significant difference between the groups in the slope of reciprocal creatinine. The latter was significantly correlated with the level of blood pressure and serum total cholesterol. Considering the outcome, all of the patients with MEH survived for 5 years. These results suggest that the more rapid progression of renal deterioration in the patients with essential hypertension might be related to the severity of hypertension and to lipid abnormalities during antihypertensive therapy.

Aged↗

[Hemoperfusion and plasma exchange therapy in patients with paraquat poisoning].

In these past three years, we treated 5 patients who attempted suicide by taking paraquat, a herbicide that had been kept at home, by direct hemoperfusion (DHP) alone or in combination with double filtration plasmapheresis (DFPP) in addition to conservative therapy. DHP alone was performed on 3 patients, 2 of whom recovered. The other 1 patient treated by DHP alone and 2 treated by the combination therapy died. These patients showed a plasma paraquat concentration exceeding the survival curve presented by Proudfoot. In such patients, appropriate combinations among hemodialysis, hemofiltration, DHP, and DFPP may be safer and more effective than each therapy alone.

Adult↗