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Biomedical subjects

A H Jackson

Publications and source records attributed to A H Jackson.

At least 37 records · Page 2Linked to original sources
PubMed1982

Separation of impurities in diazinon preparations and their effect on porphyrin biosynthesis in tissue culture.

The impurities present in commercial diazinon preparations have been examined by high performance liquid chromatography with particular reference to the ability of these compounds to cause porphyrin accumulation in cultures of chicken embryo liver cells. Diazinon and its impurities are readily separated on 10 micron Partisil using cyclohexane-dioxan mixtures. The main impurities are tetraethylpyrophosphate, sulphotetraethylpyrophosphate, 2-isopropyl-6-methylpyrimid-4-one, 2-isopropyl-6-methylpyrimidin-4-thione, and 2-isopropyl-4-ethylthio-6-methylpyrimidine. A previously unreported impurity, 2-isopropyl-6-methyl-4-S-pyrimidinyl diethylthiophosphate (isodiazinon), was also detected. Both diazinon and isodiazinon cause accumulation of coproporphyrin in cultures of chicken embryo liver cells. Isodiazinon has a greater effect on porphyrin biosynthesis in the cultures than has diazinon. It is suggested that the point of interference with porphyrin biosynthesis is towards the end of the pathway.

Animals↗
PubMed1981

Acute mercury vapor poisoning. Fatality in an infant.

A 7-month-old girl succumbed to respiratory failure following exposure to high-density mercury vapor produced by heating of the metal in the home. Her course typified inhalation mercury toxic reaction, which in its focus on pulmonary damage creates a clinical picture distinct from that of chronic and oral mercury poisoning.

Accidents, Home↗
PubMed1978

Factors determining the sequence of oxidative decarboxylation of the 2- and 4-propionate substituents of coproporphyrinogen III by coproporphyrinogen oxidase in rat liver.

Coproporphyrinogen oxidase (EC 1.3.3.3) catalyses the oxidative decarboxylation of the 2- and 4-propionate substituents of coproporphyrinogen III to form protoporphyrinogen IX. A 4-propionate-substituted porphyrinogen, harderoporphyrinogen, which is also a substrate for coproporphyrinogen oxidase, is formed during the reaction. Synthetic [(14)C]coproporphyrinogens III, specifically labelled in the carboxyl carbon atoms of either the 2- or 4-propionate substituents, were used to measure the rate of decarboxylation of each substituent by rat liver coproporphyrinogen oxidase. The experimental results, together with the recognition that in all known substrates of coproporphyrinogen oxidase only those propionate groups flanked by a specific arrangement of substituents are decarboxylated, indicate that the 4-propionate group of coproporphyrinogen III cannot be attacked until the 2-propionate group has been decarboxylated. Production of (14)CO(2) from the substrate labelled in the 2-propionate group therefore measures the formation of harderoporphyrinogen, whereas (14)CO(2) from the 4-propionate-labelled substrate measures protoporphyrinogen IX formation. The rate of harderoporphyrinogen formation is about twice that of protoporphyrinogen, and this ratio is unchanged by varying the concentration of coproporphyrinogen III or by competitive inhibition of the enzyme. When coproporphyrinogen III is present in an excess, two fractions of harderoporphyrinogen can be distinguished. One accumulates during the reaction, and the other, which is destined to become protoporphyrinogen IX, does not equilibrate with added harderoporphyrinogen. It is suggested that both decarboxylations take place at the same active centre, which becomes temporarily inaccessible to coproporphyrinogen III and added harderoporphyrinogen, and that the molecule rotates after the first decarboxylation to allow the second to take place.

Animals↗