PubMed Health⌕ Search

Biomedical subjects

L Eales

Publications and source records attributed to L Eales.

At least 37 records · Page 2Linked to original sources
PubMed1980

Screening of certain anaesthetic agents for their ability to elicit acute porphyric phases in susceptible patients.

The activity of delta-aminolaevulinic acid synthetase (E.C. 2.3.1.37) (ALA-S) was measured in rat liver after the simultaneous administration of various anesthetic agents and 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC) in vivo. Flunitrazepam, Althesin and phenobarbitone caused a significant increase in the activity of the enzyme which was not observed with propanidid, etomidate and minaxolone. It is suggested that DDC-treated rat, which resembles latent human variegate porphyria, may be a more valid method of testing drugs for their ability to elicit acute porphyric phases in susceptible individuals. The anaesthetic agents which induced the activity of hepatic ALA-S in this model are not recommended in patients with genetic hepatic porphyria.

5-Aminolevulinate Synthetase↗
PubMed1980

Porphyrins in chronic renal failure.

A highly sensitive thin layer chromatographic assay was used to establish distinct anomalies in hepatic and renal prophyrin synthesis associated with chronic renal failure. Urinary and plasma coproporphyrin disappeared but plasma uroporphyrin (isomer III) levels rose. Patients on maintenance hemodialysis showed elevated red cell protoporphyrin and decreased total stool porphyrins whilst the raised plasma uroporphyrin did not pass into the dialysate, even in 2 cases of overt symptomatic porphyria. These results indicate that urinary coproporphyrin is of renal and not hepatic origin and that azotemia may reduce the activity of the enzyme uroporphyrinogen decarboxylase.

Chromatography, Thin Layer↗
PubMed1979

Familial symptomatic porphyria in South Africa.

Seven members from 3 generations of a family investigated for evidence of symptomatic porphyria (SP) were found to be affected in varying degrees by the disease. Four had cutaneous lesions, while all 7 had biochemical abnormalities diagnostic for SP in their excreta, plasma or hepatic tissue. The results were obtained using the highly sensitive technique of quantitative fluoroscanning after separation of the porphyrin methyl esters by thin-layer chromatography. This clear case of familial SP is rare in South Africa where the high incidence of the sporadic form of the disease is well documented. This study indicates that SP occurs in the following two forms: (i) the sporadic type, usually found as an uncommon associate of chronic liver disease; and (ii) the rare familial type, inherited as an autosomal dominant trait.

Adolescent↗
PubMed1979

Porphyria and the dangerous life-threatening drugs.

The dangerous life-threatening drugs have been identified in 153 acute attacks in 138 porphyric patients by establishing a consistent temporal relationship between the administration of a specific drug and the development of an acute attack. The drugs so identified have been supplemented by a number of others found to be porphyrogenic by testing with a recently devised rat model. Lists of the dangerous and the safe drugs have been compiled.

Barbiturates↗
PubMed1979

Activation of uroporphyrinogen decarboxylase by ferrous iron in porphyria cutanea tarda.

Uroporphyrinogen decarboxylase was measured in the presence of ferrous iron, using mitochondria-free rat liver extracts as enzyme source. The activity of the enzyme was found to be increased at concentrations of ferrous iron from 0,01 mM, with maximal activity exhibited from 0,1 mM. Enzyme kinetics indicate that uroporphyrinogen decarboxylase reversibly binds ferrous iron, with a binding constant of approximately 5 x 10(4) mol-1. It is proposed that the effect of phlebotomy on patients with porphyria cutanea tarda is to mobilze storage iron in the liver to the active ferrous form, which activates hepatic uroporphyrinogen decarboxylase, the enzyme which is defective in this syndrome, with resultant clinical and biochemical remission.

Animals↗
PubMed1978

The effects of canthaxanthin on the photocutaneous manifestations of porphyria.

An open trial with canthaxanthin, a photoprotective agent, was carried out on 7 patients with erythrohepatic protoporphyria (EHP), 5 patients with variegate porphyria (VP), and 2 patients with symptomatic porphyria (SP). In 4 of the 7 patients with EHP, sun tolerance was significantly but only moderately increased. In 2 children sun tolerance was greatly increased. Only 2 of the 5 patients with VP and 1 of the 2 patients with SP showed any improvement.

Adolescent↗
PubMed1978

Quantitation of red cell porphyrins by fluorescence scanning after thin-layer chromatography.

This paper reports a new method for the quantitative determination of erythrocyte and plasma porphyrins by fluoroscanning of the methyl esters separated by thin-layer chromatography (TLC). After esterification overnight in the dark the polycarboxylated porphyrin methyl esters were extracted into chloroform and aliquots applied to the TLC plates within the range of quantities shown in a preliminary study to be directly proportional to fluorescence intensity. The accuracy and reliability of the technique was tested by comparison of RBC protoporphyrin values obtained by TLC with an established quantitative porphyrin solvent extraction method and with a rapid method presently in common use. Good correlation was demonstrated between the solvent extraction and the TLC techniques. The high sensitivity and adaptability of the TLC technique and its ability to clearly separate all the porphyrins present in the samples are discussed, along with the fluorescence mechanisms involved and the effects of instrumentation.

Chromatography, Thin Layer↗
PubMed1978

The nature of hepatic cytochrone P-450 induced in hexachlorobenzene-fed rats.

1. The effect of feeding with a diet containing 0.2% (w/w) hexachlorobenzene on hepatic and urinary porphyrins and hepatic cytochrome P-450 was studied at various time intervals in female Wistar rats. 2. Hexachlorobenzene administration for 45 days resulted in the development of porphyria in rats, which biochemically closely resembles symptomatic porphyria in humans, with elevation of urinary uroporphyrin excretion, hepatic uroporphyrin content, and hepatic cytochrome P-450 content, in addition to appearance of porphyrins of the isocoproporphyrin (P1) series in the faeces. 3. Spectral studies of the induced hepatic cytochrone P-450 at 45 days with carbon monoxide and ethyl isocyanide as ligands indicated the presence of a greater admixture of a haemoprotein distinct from cytochrome P-450. 4. Study in vitro of the kinetics of two reactions, namely aminopyrine N-demethylation and 3,4-benzpyrene hydroxylation, catalysed by the hepatic microsomal cytochrom P-450-dependent enzyme system, suggested that hexachlorobenzene induced a form of cytochrome P-450-dependent enzyme system, suggested that hexachlorobenzene induced a form of cytochrome P-450 with different catalytic properties from those of forms induced by either phenobarbital or 3-methylcholanthrene.

Animals↗
PubMed1978

Protoporphyrin (proto)-determined hepatopathy in a South African Jewish family.

A detailed study of a Jewish erythrohepatic protoporphyria (EHP)-affected family with a sibship consisting of 2 brothers and a sister, all of whom manifested protodetermined hepatopathy which varied from relatively mild hepatic involvement in the sister to a fulminant fatal illness in the eldest brother. The nature and course of his illness as well as the autopsy findings are described in detail. This sibship is also unique in that the 2 brothers and biochemical evidence of a severe degree of G6PD deficiency, while the sister was shown to be a carrier.

Adult↗
PubMed1978

The use of the rat in the experimental investigation of the porphyrias.

The patterns of urinary porphyria excretion and hepatic porphyrin accumulation in hexachlorobenzene-treated rats is similar to that observed in overt porphyria cutanea tarda and may be attributed to a decrease in activity of hepatic uroporphyrinogen (UROGEN) decarboxylase. The 3.5 diethoxycarbonyl-1,4-dihydrocollidine (DDC)-treated rat has been evaluated as a model to test the porphyrinogenicity of drugs.

Animals↗
PubMed1977

Erythrocyte electrolyte content and sodium efflux in chronic renal failure.

The cation content of the eythrocyte was studied in 36 patients with chronic renal failure; A normal or high erythrocyte potassium was found. Erythrocytes sodium values showed a wide range, from very high to very low, and the rate constant for Na efflux was found to be higher than normal. The interpretation of these findings is discussed. It is suggested that the higher than normal. The interpretation of these findings is discussed. It is suggested that the high erythrocyte K content may reflect abnormal total body K, may be explained on the basis of a young red cell population or may be related to abnormal function of the erythrocyte cation pump. It is probable that the development of these changes in chronic renal failure depends on many factors.

Adolescent↗