Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 3 de 3
Filter
Add more filters










Database
Language
Publication year range
1.
Clin Chim Acta ; 230(1): 91-9, 1994 Oct 14.
Article in English | MEDLINE | ID: mdl-7850997

ABSTRACT

The identity of two formerly novel citric acid analogues, homocitric acid and methylhomocitric acid, in urine samples from patients with propionic acidaemia was confirmed by gas chromatography and mass spectrometry. Authentic reference substances were synthesized using a Reformatskii reaction. Homocitric acid and methylhomocitric acid were detected as minor metabolites in the urine samples from propionyl coenzyme A carboxylase deficient individuals. It was shown that these substances can be formed by the citrate synthase condensation reaction of alpha-ketoglutarate with acetyl coenzyme A and propionyl coenzyme A, respectively.


Subject(s)
Acidosis/urine , Citrate (si)-Synthase/metabolism , Propionates/urine , Tricarboxylic Acids/urine , Acidosis/diagnosis , Carboxy-Lyases/deficiency , Female , Gas Chromatography-Mass Spectrometry , Humans , Infant, Newborn , Ketoglutaric Acids/chemistry , Male , Methylmalonyl-CoA Decarboxylase , Reference Standards , Tricarboxylic Acids/chemical synthesis
2.
J Inherit Metab Dis ; 17(6): 738-47, 1994.
Article in English | MEDLINE | ID: mdl-7707698

ABSTRACT

The absolute separation of the four stereoisomeric configurations of methylcitric acid can be achieved on a nonchiral stationary phase SE30 capillary column using the corresponding O-acetylated (tri-(-)-2-butyl ester derivatives. Identification of the separated isomers was done using methylcitric acid produced by si-citrate synthase and methylcitrate synthase of Candida lipolitica. si-Citrate synthase produces the (2S,3S)-, (2S,3R)- and a small amount of the (2R,3S)-isomers. Methylcitrate synthase produces the (2R,3S)-isomer, indicating that this enzyme is more stereospecific than the animal citrate synthase enzyme. The (2R,3R)-isomer may act as an inhibitor of aconitase.


Subject(s)
Citrate (si)-Synthase/metabolism , Citrates/chemistry , Citrates/biosynthesis , Gas Chromatography-Mass Spectrometry , Stereoisomerism
3.
Ann Otol Rhinol Laryngol ; 85(4 Pt 2 Suppl 29): 1-58, 1976.
Article in English | MEDLINE | ID: mdl-962272

ABSTRACT

A method was evolved by which the organ of Corti could be examined in its entirety with the scanning electron microscope, the organ meanwhile retaining its spiral form. This made it possible to assess traumatic effects on the cochlea and qualify lesions in terms of extent, localization and pattern. It was also found possible eventually to cut the same specimen into sections for cellular and subcellular studies. The number of guinea pigs examined totalled 91, divided into three groups. The first group was used to study the anatomy of the organ of Corti with special reference to normal variations and artifacts. Unmistakable indications were found that the longest stereocilia of the inner hair cells are linked to the tectorial membrane. The animals of the second group were exposed to pure tones of high intensity, whereupon, lesions of the organ of Corti were described according to intensity, time, and frequency. Three different types of otologic drills were used to perform mastoidectomies on temporal bones and on the cadaver. The noise produced was analyzed as to intensity and frequency range. It was found that the drill with the lowest rpm (and highest torque) produced the highest noise intensities, at levels which can be traumatic to the human organ of hearing. The animals of the third group were exposed to the amplified noise produced by otologic drills of three different types. The resulting lesions in the organ of Corti were examined by the method described for scanning electron microscopy and compared. In spite of the wide variation in individual lesions, patterns of degeneration of three different types could be distinguished. The high-speed and the very-high-speed drill inflicted less damage on the organ of Corti than the low-speed drill. It is therefore advised to refrain from using the latter drill in prolonged operations.


Subject(s)
Hearing Loss, Noise-Induced/pathology , Microscopy, Electron, Scanning , Organ of Corti/ultrastructure , Animals , Cochlea/anatomy & histology , Ear/surgery , Guinea Pigs , Hearing Loss, Noise-Induced/etiology , Organ of Corti/pathology , Otolaryngology/instrumentation , Sound/adverse effects , Surgical Instruments , Surgical Procedures, Operative/adverse effects
SELECTION OF CITATIONS
SEARCH DETAIL
...