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Biomedical subjects

N Takai

Publications and source records attributed to N Takai.

At least 55 records · Page 3Linked to original sources
PubMed1997

Analysis of peptides and proteins by temperature-responsive chromatographic system using N-isopropylacrylamide polymer-modified columns.

A new method of HPLC using packing materials modified with a temperature responsive polymer, poly(N-isopropylacrylamide) (PIPAAm), was developed. Homogeneous PIPAAm polymer and its copolymer with butyl methacrylate (BMA) were synthesized and grafted to aminopropyl silica by activated ester-amine coupling and they were used as packing materials. The surface properties and functions of the stationary phases are controlled by external temperature. Isocratic elution by aqueous mobile phase alone is the basis for separation of peptides and protein. The separation of the mixture of three peptides, insulin chain A and B and beta-endorphin fragment 1-27 was achieved by changing the column temperature with 0.9% NaCl aqueous solution as the sole eluent. Retention of peptides and proteins was controlled both by column temperature and by NaCl concentration in the aqueous mobile phases in this chromatographic system.

Acrylamides↗
PubMed1996

Acidic catecholamine metabolites and 5-hydroxyindoleacetic acid in urine: the influence of diet.

Concentrations of vanillylmandelic acid (VMA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), vanillic acid (VA) and 5-hydroxyindoleacetic acid (5-HIAA) in urine from healthy subjects were determined by a high-performance liquid chromatography system with a mixed-mode (C18/anion-exchange) column and an 8-channel electrochemical detector, in order to study the influence of diet, diurnal variation and age. The urinary excretion of 5-HIAA increased significantly after eating banana, pineapple, tomato, kiwi fruit and walnut. An increase in the urinary excretion of DOPAC and HVA after eating banana and that of VA after taking vanilla was also noted. The urinary excretion of VMA was not significantly influenced by any of the foods examined. The urinary excretion of 5-HIAA in the first-morning urine increased beyond the upper limit of the reference value when banana was taken at 2000 h the previous day. The excretion of all metabolites in the second-morning urine in the fasting state was within respective reference ranges. Diurnal variation of the excretion of VMA, DOPAC, HVA and 5-HIAA in urine was relatively small, but that of VA was large. The concentrations (mmol/mol creatinine) of VMA, DOPAC, HVA, 5-HIAA and VA in the first-morning urine from healthy subjects increased from 7 days after birth to 1 year and then decreased to adult levels at 13 years of age.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1995

Chorda-evoked opening of tight junctions in rat submandibular salivary acini demonstrated by microperoxidase.

The permeability of these junctions from the interstitium to the lumen was examined by using an ultrastructural tracer, microperoxidase, in conjunction with electron microscopy. In the resting gland, the reaction product of microperoxidase was seen in the interstitial and intercellular spaces, but not within acinar lumina; thus the tight junction was impermeable to microperoxidase (junction closed). Intraductal injection of hypertonic sucrose solution (1000 mOsm; 30 microliters) caused a sustained elevation of the luminal pressure, indicating osmotic water flow into the lumen due to the presence of a hypertonic solution. In this gland no opening of the tight junctions was observed. In the chorda-stimulated gland, microperoxidase entered the lumen through the tight junctions, that is, they became permeable to microperoxidase (junction open). These findings suggest that chorda stimulation opens the acinar tight junctions and that the paracellular secretory pathway may be involved in the secretion of small molecules and water from the submandibular acini.

Animals↗
PubMed1995

Role of amino acids in salivation and the localization of their receptors in the rat salivary gland.

The distribution of gamma-aminobutyric acid (GABA) receptor subunits such as GABAAR-gamma 1 and GABAAR-gamma 2, and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) type receptor subunits such as GluR-1, GluR-2/3 and GluR-4, and N-methyl-D-aspartic acid (NMDA) type subunits such as NR1 were investigated by immunocytochemistry. Furthermore, the roles of these amino acids, GABA and glutamate, on salivation were analyzed in the rat submandibular and sublingual glands. Some similarities were observed in the distribution patterns of GABAA type receptors and AMPA receptors. In the submandibular ganglion cells, collecting ducts and striated ducts, these subunits were expressed strongly; however, there were some differences in their expression patterns between the submandibular and sublingual gland acinar cells. Since these receptor subunits were expressed in the acinar cell bodies of the submandibular gland, they were not expressed in the acinar cells but were expressed in the myoepithelial cells in the sublingual gland. On the other hand, no NR1 expression was observed. To examine the roles of GABA and glutamate in salivation, the submandibular and sublingual glands were perfused partially with Ringer's solution via a facial artery to avoid systemic influence, and substrates were infused into the perfusion solution. No salivary secretion was evoked by GABA or glutamate infusion in the absence of electrical stimulation (2-3 V, 5 ms, 20 Hz). Salivary flow evoked by electrical stimulation of the chorda-lingual nerve caused significant inhibition by GABA (10(-6), 10(-5), 10(-4) and 10(-3) M) and the GABAAR agonist muscimol 10(-3) and 10(-6) M) (n = 6, P < 0.05). Such GABA-induced inhibition was antagonized by the GABAAR antagonists bicuculline (BCC; 10(-6) and 10(-3) M) and picrotoxin (PTX; 10(-6) and 10(-3) M). On the other hand, salivary flow evoked by electrical stimulation (8-10 V, 5 ms, 20 Hz) of the superior cervical ganglion (SCG) was not affected by GABA. While high doses of glutamate (10(-1) M) and NMDA (10(-1) M) showed no effects on salivary flow despite application of electrical stimulation, AMPA at a high concentration (10(-1) M) significantly inhibited salivary secretion (n = 6, P < 0.05). These studies revealed that inhibitory and excitatory amino acid receptors such as GABAA and AMPA type receptors are coexpressed in the rat salivary glands, and that GABA inhibits salivary secretion via GABAA receptors which may act with acetylcholine. However, the role of glutamate in salivation remains unclear despite the presence of AMPA type receptors. The present findings suggest that glutamate does not act alone but with other substances such as peptides and/or other amino acids.

Animals↗
PubMed1995

Immunohistochemical study of c-erb B-2 protein expression in endometriosis.

Using immunohistochemical techniques, we studied the expression of c-erb B-2 in normal human endometrial tissue (n = 8), endometriosis interna (adenomyosis) (n = 8) and endometriosis externa (endometriotic cyst of the ovary) (n = 6). The glandular epithelium of normal endometrial tissue specimens in the proliferative phase stained positively. Most of the cases of endometriosis studied showed no expression of c-erb B-2 in glandular epithelium. No expression was detected in either the normal or endometriotic stromal cells. Results suggest that c-erb B-2 is not significantly involved in the pathogenesis of endometriosis.

Adult↗
PubMed1995

Infant with thanatophoric dwarfism in triplet pregnancy.

The case of a Japanese female infant with thanatophoric dwarfism, a triplet, is reported. The diagnosis was made at 18 weeks' gestation. Triplets were delivered at 30 weeks' gestation by cesarean section. Two infants, both males, were normal; the female with dwarfism died of respiratory distress 34 min after delivery. This is the first known case of one fraternal triplet being affected by thanatophoric dwarfism.

Fatal Outcome↗
PubMed1994

High-performance liquid chromatographic determination of catecholamine metabolites and 5-hydroxyindoleacetic acid in human urine using a mixed-mode column and an eight-channel electrode electrochemical detector.

An HPLC system for the simultaneous determination of acidic catecholamine metabolites, related compounds and 5-hydroxyindoleacetic acid (5-HIAA) in human urine was developed. A mixed-mode (C18/anion-exchange) column with isocratic elution using citrate buffer and an eight-channel electrochemical detector were used. Vanilmandelic acid (VMA), 3,4-dihydroxyphenylacetic acid (DOPAC), 4-hydroxy-3-methoxyphenyllactic acid (vanillactic acid, VLA), homovanillic acid (HVA), vanillic acid (VA) and 5-HIAA in urine were determined simultaneously. Detection limits and inter (n = 5) and intra-assay (n = 5) coefficients of variation were satisfactory. The mean of analytical recoveries (n = 3, +/- C.V. (%)) were between 97 +/- 3.2 (VMA) and 105 +/- 4.8 (VA). Correlations between the analytical results for VMA, HVA and 5-HIAA obtained by an established method and the present method were satisfactory. The mean +/- 2 S.D. of the excretion rates of VMA, DOPAC, VLA, HVA, 5-HIAA and VA in urine from healthy adult volunteers were 0.61-4.36, 0.13-1.02, 0-0.35, 0.67-6.55, 0.50-5.14 and 0-0.55 mg/g creatinine, respectively.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1994

[Simultaneous determination of catecholamines, serotonin, and their precursors and metabolites in body fluid by an HPLC system with multi-electrode electrochemical detector].

We have developed two HPLC systems for the simultaneous determination of CA, 5-HT and their precursors and metabolites in human body fluid. One system consisted of two reversed-phase columns, a column switching device, a pair of electrodes for elimination of interferents and two sets of new electrochemical detectors with four electrodes. Using this system, adequate separation of peaks for 17 kinds of CA, 5-HT and their related metabolites in a standard solution required only 17 min. NE, MHPG, DOPAC, 5-HIAA, HVA and TRP levels in cerebrospinal fluid (CSF) were determined without any pretreatment of the CSF samples. The concentrations of DOPAC, 5-HIAA and HVA in CSF were significantly lower in Alzheimer's disease, vascular dementia and Parkinson's disease than in the controls. The other system was developed for determination of CA acidic metabolites and 5-HIAA in human urine. This system consisted of a mixed-mode column (C18/anion) and 8-channel electrochemical detector with isocratic elution of citrate buffer. Detection limits, precision and analytical recoveries of this method were satisfactory for clinical use.

Aged↗
PubMed1993

Liquid chromatography-mass spectrometry for the determination of medetomidine and other anaesthetics in plasma.

A liquid chromatographic-atmospheric pressure chemical ionization mass spectrometric method is presented for the simultaneous determination of medetomidine and other anaesthetic drugs in solutions and dog plasma. The drugs examined were flumazenil, butorphanol, atropine, ketamine, xylazine, medetomidine, atipamezole and midazolam. The separation was carried out on a reversed-phase column using methanol-0.1 M ammonium acetate (3:2) as eluent.

Anesthetics↗
PubMed1993

Determination of acidic saponins in crude drugs by high-performance liquid chromatography on octadecylsilyl porous glass.

High-performance liquid chromatographic (HPLC) analysis on octadecylsilyl porous glass was investigated for acidic saponins in ginseng, bupleurum root and senega. The acidic saponins, malonyl-ginsenosides, malonyl-saikosaponins and senegins, as well as neutral saponins in the crude drugs were separated rapidly by HPLC on this column with aqueous acetonitrile containing KH2PO4 as the mobile phase at room temperature.

Carbohydrate Sequence↗
PubMed1993

Isolation and identification of canine plasma components suspected as uremic toxins.

Suspected uremic substances contained in four fractions, which had been selected as the suspected canine uremic peaks in the previous study, were isolated by two stages of preparative liquid chromatography (PLC) from plasma of uremic dogs treated with the ligation of the ureter, and then their physicochemical properties were examined. The primary separation of the suspected uremic peaks were performed with the same anion exchange resin as used in the analytical HPLC in the previous study. Analytical reverse phase HPLC showed that three of 4 suspected uremic peaks almost consisted of single substances, but the other contained several substances. Main subfractions of these peaks were successfully isolated by the secondary stage reverse phase PLC. By means of thin layer chromatography, ultraviolet absorption spectrometry and proton-nuclear magnetic resonance spectroscopy, components of 4 main peaks were confirmed to be small molecules such as a pyridine derivative, uric acid, hippuric acid and kynurenic acid, respectively.

Animals↗
PubMed1993

Surgical intervention for angiographically unexplained subarachnoid hemorrhage--report of three cases.

We report three patients with subarachnoid hemorrhage in which no causative lesion was detected angiographically. Surgical intervention revealed a ruptured aneurysm in all three cases, which were clipped successfully. Although the prognosis for a patient with subarachnoid hemorrhage of unknown cause is good, there still remain long-lasting unpleasant complaints probably arising from psychogenic factors. We especially recommend exploratory craniotomy when subarachnoid hemorrhage is located anterior to the circle of Willis, accompanied by thick and obviously lateralizing subarachnoid clots on computed tomography and/or rebleeding in the same anatomical location, even if no causative lesions can be found angiographically.

Adult↗
PubMed1993

Vertebral artery dissecting aneurysm rebleeding after proximal occlusion--case report.

A 38-year-old male presented with vertebral artery dissecting aneurysm manifesting as subarachnoid hemorrhage. An attempt at trapping the aneurysm failed, so the vertebral artery could only be clipped proximally. Rebleeding occurred, resulting in death, probably due to excessive length of the dissection requiring thrombosis and/or retrograde dissection due to back pressure from the contralateral vertebral artery.

Adult↗
PubMed1992

Detection of uremic peaks in dogs by anion exchange high performance liquid chromatography.

Sera of dogs with gentamicin-induced uremia were analyzed by high performance liquid chromatography system with strongly basic macroreticular anion exchange resin. Satisfactory separation of peaks was achieved with good reproducibility after deproteinization of sera with trichloroacetic acid at a final concentration of 3%, confirming that the system was suitable for qualitative analysis of uremic serum. The chromatograms showed that the number of peaks and the peak area had relation to concentrations of serum urea nitrogen or creatinine and severity of uremia. Four peaks were selected as suspected canine uremic peaks with high correlation to serum creatinine concentrations which were hardly influenced by extrarenal factors. The results suggested that these four fractions might contain uremic toxins.

Animals↗
PubMed1992

Comparison of late and early stage surgery for ruptured intracranial aneurysms.

Surgical indications and timing in serious cases (Hunt and Hess grades 4 and 5) of intracranial aneurysms were investigated. The outcomes in early surgery were compared to the clinical courses of cases intended for late surgery. The survival rate of early surgery patients was 64.4%, better than the total of improved (28.3%) and survived (6.5%) patients for late surgery. There were 28.8% good outcomes in the early surgery group, compared to 2.2% in those treated late. Both of these figures are statistically significant. We consider that early surgery is indicated for serious cases, but not for grade 5 patients with hematoma.

Aged↗