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Biomedical subjects

M Kai

Publications and source records attributed to M Kai.

At least 199 records · Page 11Linked to original sources
PubMed1983

Measurement of leucine enkephalin in caudate nucleus tissue with fast atom bombardment-collision activated dissociation-linked field scanning mass spectrometry.

The endogenous amount of the opioid pentapeptide leucine enkephalin was measured in a canine caudate nucleus tissue extract using mass spectral analytical methods which retain absolute molecular specificity. Fast atom bombardment mass spectrometry generation of the protonated molecular ion of leucine enkephalin followed by collision activated dissociation produced amino acid sequence-determining ions. These amino acid sequence-determining ions were analyzed by a linked field (B/E) scan. One amino acid sequence-determining ion was selected to measure endogenous leucine enkephalin. This novel measurement mode offers optimal molecular specificity for quantification of an endogenous amount (451 pmol g-1 tissue) of leucine enkephalin in a biologic tissue extract of canine caudate nucleus.

Animals↗
PubMed1983

Preparation of stable isotope-incorporated peptide internal standards for field desorption mass spectrometry quantification of peptides in biologic tissue.

Stable isotopes have been incorporated into two opioid pentapeptides, leucine enkephalin and methionine enkephalin, using chemical- and enzymatic-catalyzed reactions. Oxygen-18 from H218O was the stable isotope incorporated. High-performance liquid chromatography separated the chemical reaction mixture into three fractions: hydrolyzed peptide fraction, 18O-incorporated enkephalin, and 18O-incorporated enkephalin ester. Analysis of individual isotopic species (18O2, 18O16O, 16O2) in the latter two fractions was done with field desorption mass spectrometry. Porcine esterase II was used to hydrolyse enkephalin esters and recover stable isotope. Up to 90% 18O2 was incorporated. Yields of 18O2 species for the overall procedure were for leucine enkephalin, 56%, and for methionine enkephalin, 38%. This scheme represents the first fast and facile preparation of a stable isotope-incorporated peptide internal standard for use in measuring peptides in biologic extracts and is readily extended to any peptide with a free carboxyl group. Fast atom bombardment-collision activated dissociation-linked field (B/E) scan mass spectrometry unambiguously locates the two 18O atoms in the carboxyl group of the peptide and not in a peptide amide bond or tyrosine side chain. The two 18O-labeled peptide internal standards were used to measure, in a structurally unambiguous fashion, endogenous leucine enkephalin and methionine enkephalin in thalamus tissue at the ppb level. A microcomputer was used for data acquisition and reduction.

Animals↗
PubMed1982

Digital processing methods using scanning densitometer and microcomputer for the structural analysis of a scanning electron micrograph.

The fundamental equation of image contrast with practical resolving power is shown taking account of the optical and specimen characteristics. Then, the structural factor which is used to indicate the scattering from the unit of structure to form the periodic object in a scanning electron microscopy can be derived straight-forwardly by digital processing. Based on the Fourier analysis, the reconstruction and subsequent interpretation of structural images such as biological specimens of rat microvilli have been successful. These microvilli must exhibit regularity of a hexagonal lattice consisting of rod-like crystalline arrays. Lattice defects are analysed by means of contrast enhancement, level slicing and histogram plotting techniques. The resolution of SEM can be tested from the granularity distance of coated films by the image sharpening by differentiation and subsequent superimposition of reconstructed images. Furthermore, the structural details in high brightness owing to reducing of the brightness level and filtering the high frequency component have been analysed.

Animals↗
PubMed1981

Determination of phenylpyruvic acid in urine and serum by high-performance liquid chromatography with fluorescence detection.

A highly sensitive and simple method for the determination of phenylpyruvic acid in urine and serum is described which employs high-performance liquid chromatography with fluorescence detection. Phenylpyruvic acid, after extraction with ethyl acetate, is reacted with 4'-hydrazino-2-stilbazole in aqueous methanol to give the corresponding fluorescent hydrazone which is separated by reversed-phase chromatography on muBondapak Phenyl. The lower limits of detection are 25 and 32 pmol for phenylpyruvic acid in 0.2 ml of urine and serum, respectively. This sensitivity permits the determination of the acid in urine or normal adults and newborn infants.

Adult↗
PubMed1981

The pathogenesis of small arterial lesions in nephrectomized rats by the administration of renin.

Intraperitoneal injection of purified hog renal renin produced a marked and sustained elevation of arterial pressure and lesions of the "fibrinoid necrosis" type in the small arteries and arterioles of the pancreas, heart and mesentery, but not of the brain, in bilaterally nephrectomized rats. Both the elevation of arterial pressure and the production of arterial lesions were completely prevented by pretreatment with oral SQ14225. Plasma renin clearance in bilaterally nephrectomized rats was markedly slower than that in sham-nephrectomized rats. Pre-treatment with oral SQ14225 did not affect renin clearance. It is suggested that sustained high blood pressure due to the sustained high plasma renin concentration in bilaterally nephrectomized rat was responsible for the production by renin of lesions of the fibrinoid necrosis type in the arteries.

Animals↗
PubMed1980

Fluorimetric assay for ornithine decarboxylase by high-performance liquid chromatography.

A highly sensitive method for the assay of ornithine decarboxylase in sample solutions prepared from rat tissue homogenate is described which employs high-performance liquid chromatography with fluorescence detection. Putrescine formed from ornithine under the optimal conditions for the enzyme reaction is treated by Cellex P column chromatography for clean-up and converted into the fluorescamine derivative in the presence of cupric ion which inhibits the reaction of interfering amines with fluorescamine. The derivative is separated by reversed-phase chromatography on LiChrosorb RP-18 with linear gradient elution. The lower limit of detection for putrescine formed enzymatically is 5 pmol.

Animals↗
PubMed1980

Fibrinoid degeneration and increased vascular permeability induced by renal lysosomal contents. An electron microscopic study on coronary and cerebral arteries of rats.

The effect of the lysosomal contents of hog kidney cortex, especially of the fraction not bound by concanavalin A (Fraction A) on the permeability of the coronary and cerebral arteries of rats was studied ultrastructurally using H.R. peroxidase. This fraction was devoid of renin activity by bioassay. The coronary arteries of the experimental rats displayed fibrinoid degeneration: e.g., degeneration and disappearance of medial smooth muscle cells and deposition of electron dense materials containing fibrin. A large amount of reaction product of peroxidase was present in the subendothelial space and media where fibrinoid degeneration was evident. Transendothelial passage of the marker occurred by both junctional and vesicular transport. There was no evidence of separation or discontinuity of the endothelial cells. Occasionally, increased permeability of the intima was noted in the coronary arteries without medial damage. By contrast, neither fibrinoid degeneration nor increased permeability was noted in the cerebral arteries. The difference in the response of the two arteries seems attributable to the barrier effect of cerebral arterial intima.

Animals↗
PubMed1979

High-performance liquid chromatographic determination of free and total polyamines in human serum as fluorescamine derivatives.

A highly sensitive and simple fluorimetric method for the determination of free and total polyamines, spermidine, spermine, putrescine and cadaverine, in human serum by high-performance liquid chromatography is described. The polyamines, obtained after clean-up of deproteinized serum by Cellex P column chromatography, are converted to their fluorescamine derivatives in the presence of nickel ion which inhibits the reaction of interfering amines with fluorescamine, and the derivatives are separated simultaneously by reversed-phase chromatography (LiChrosorb RP-18) with a linear gradient elution. The lower limits of detection are 10 and 15 pmole for spermine and the others in 0.5 ml of serum, respectively.

Adult↗
PubMed1979

Higher levels of erythrocyte membrane microviscosity in diabetes.

Significantly higher levels of erythrocyte membrane microviscosity (MV) [n-: 5.22 +/- 0.17 (4.70--5.92), mean +/- SD (range), poise, N = 67, P less than 0.005] measured by fluorescence depolarization using 1,6-diphenyl-1,3,5-hexatriene as a fluorescent probe were found in diabetic patients when compared with normal controls [5.05 +/- 0.15 (4.70--5.29), N = 22]. No significant differences in MV existed between males and females, nor was MV significantly correlated with diabetic age, duration of diabetes, plasma cholesterol, cholesterol/phsopholipid ratios, and plasma lecithin:cholesterol acyltransferase activities. No significant difference in MV was observed between groups with or without diabetic retinopathy. There was, however, significantly higher MV [5.29 +/- 0.19 (5.00--5.92), N = 20, P less than 0.05] in the group with fasting blood glucose (FBG) greater than or equal to 140 mg/dl than that [5.19 +/- 0.15 (4.70--5.46), N = 47] in the group with FBG less than 140 mg/dl. The changes in erythrocyte membrane MV presented in this study appear to be related to the current metabolic control of diabetic patients and are considered to be one of the factors responsible for the reduced erythrocyte deformability in diabetes.

Diabetes Mellitus↗