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R A Harkness

Publications and source records attributed to R A Harkness.

114 records · Page 7Linked to original sources
PubMedDate not supplied

Nucleotide, nucleoside and purine base concentrations in human placentae.

Nucleotides, nucleosides and purine bases in trichloroacetic acid extracts of freeze clamped samples of human placenta have been measured by high-pressure liquid chromatography. The concentrations of the nucleotides concerned with energy transduction, ATP, ADP and AMP, and especially the energy charge, are stable over periods of ischaemia of 30 min. Concentrations of 14 nucleotides, including UDPAG, GDP Man, UDP and CTP, have now been defined. In addition, the concentrations of hypoxanthine, xanthine, uridine, adenine and inosine are indicated. Concentrations of the vasodilator adenosine are similar to the apparent Michaelis constants of its main metabolizing enzymes adenosine kinase and adenosine deaminase. The availability of 'normal' values of adenine nucleotide concentrations in human placenta should permit the detection of 'placental insufficiency' of energy supply, if this condition exists.

Cesarean Section↗
PubMedDate not supplied

The placenta in leprosy.

Eighty-one placentae from women with leprosy and 17 placentae from healthy controls were subjected to a detailed macroscopic, light microscopic, ultrastructural, immunopathological, microbiological and biochemical study. The placental morphology and immunohistology were normal, and there was no morphological evidence of infection of the placenta due to M. leprae. No acid-fast bacilli or acid-fast bacillary granules were seen on light microscopy of any of the placentae from leprous women, although homogenates from two out of seven placentae from women with very active lepromatous leprosy contained acid-fast bacilli in very small numbers. The small placental size of women with leprosy, most marked in those with lepromatous leprosy, appears to be due to a decrease in placental cell size, rather than to a reduced number of cells in the placenta. It is postulated that the small placenta and reduced fetal birth weight observed in lepromatous leprosy are a consequence of depressed maternal immune reactivity.

Complement System Proteins↗
PubMedDate not supplied

Human placental mitochondrial respiration and its regulation by adenine nucleotides.

Respiratory parameters were studied in mitochondria from human placenta. Respiratory control and ADP/O ratios were low in this preparation. The adenine nucleotide content of placental mitochondria was found to be only one quarter of that found for adult uterine muscle tissue mitochondria prepared in the same way. Loading placental mitochondria with adenine nucleotides by incubation in the presence of ATP produced increased respiratory control ratios but no improvement in ADP/O ratios. Our evidence is consistent with the developmental changes shown to occur in rat liver, in which an increased concentration of adenine nucleotides is responsible for changes in respiratory parameters.

Adenine Nucleotides↗
PubMedDate not supplied

Effect of a failure of energy supply on adenine nucleotide breakdown in placentae and other fetal tissues from rat and guinea pig.

The effects of ischaemia on adenylate energy charge of tissues from fetal rats and fetal guinea pigs were measured. Adult rat and guinea-pig tissues, as well as human placentae, were also studied. The largest differences observed were between the fetuses from different pregnant animals (P = 4.74 X 10(-15). Reductions in energy charge in placentae were slower than in other defined fetal tissues, especially brain. In the rat, an immature species at birth, greater 'stability' was observed in placentae of 14 days of gestation than near term at 20 days of gestation. As contrast, in the guinea pig, a mature species at birth, there was no difference in 'stability' in placenta or other fetal tissues between about 40 days of gestation and near term, about 60 days of gestation. In addition to these tissue and maturity effects in the fetus, it has been confirmed that fetal tissues are more 'resistant' than adult tissues to failures of energy supply. Concentrations of adenosine, uridine, guanosine and cytidine nucleotides in placenta show similar patterns in rats and guinea pigs. Fetal liver contains more uridine nucleotides and brain more cytidine nucleotides. It is suggested that the placenta retains an early fetal ability to maintain itself during ischaemia; this might be advantageous during parturition. Possible endocrine and other mechanisms 'damping' fetoplacental metabolism are linked with a discussion of the large maternal effect.

Adenine Nucleotides↗