Fetal surfactant as a source of arachidonate in human amniotic fluid.

The factors responsible for the onset of labor in women are not well understood but it is clear that parturition is associated with increased production of prostanoids and release of arachidonic acid by intrauterine tissues. Pulmonary surfactant is secreted from the fetal lung into the amniotic fluid where its concentration increases toward term. In this paper we have shown that the ability of fetal surfactant to stimulate prostaglandin production by amnion cells is greatly enhanced by pre-incubating surfactant with amniotic fluid.

Surfactant proteins A (SP-A) and D (SP-D): levels in human amniotic fluid and localization in the fetal membranes.

Surfactant proteins A (SP-A) and D (SP-D) are major proteins, in the lung, which are composed of collagenous and globular domains. They show an overall similarity to the serum complement protein Clq, which is involved in the initiation of antibody-dependent defence mechanisms. Both SP-A and SP-D were detected, immunochemically, in amniotic fluid as early as 26 weeks gestation and, as expected, SP-A levels rose sharply from 32 weeks towards term.

Utilization by human amniocytes for prostaglandin synthesis of [1-14C]arachidonate derived from 2-[1-14C]arachidonylphosphatidylcholine associated with human fetal pulmonary surfactant.

The phospholipids of human fetal pulmonary surfactant prepared from term amniotic fluid contained arachidonic acid and its utilization for prostaglandin synthesis by amnion cells has been investigated. Cells were incubated with surfactant labelled with L-alpha-1-palmitoyl-2-[1-14C]arachidonylphosphatidylcholine. The uptake of radioactivity into amniocyte phospholipids increased with time and with the concentration of surfactant and after 2 h of incubation at 37 degrees C, 63% of the incorporated radioactivity was recovered in phosphatidylethanolamine (PE) and phosphatidylinositol (PI).

Platelet-activating factor levels in human follicular and amniotic fluids.

Platelet-activating factor (PAF) was estimated in extracts of human follicular and amniotic fluids using a commercially available 125I-radioimmunoassay. Levels obtained before and after purification of the extracts by thin-layer chromatography were similar and PAF could be estimated with high accuracy and reproducibility over a wide dilution range. PAF levels in fluid aspirated from mature (17 mm average diameter) follicles from in vitro fertilization patients were 1005 +/- 129 fmol/ml in successful (clinical pregnancy) cycles and 949 +/- 75 fmol/ml in unsuccessful (failure of implantation) cycles.

Human placental phospholipase A2 activity in term and preterm labour.

Phospholipase A2 activity (EC 3.1.1.

Adsorption of fetal surfactant protein SP-B on the human amnion at term and on amniocytes incubated with fetal surfactant in vitro.

Fetal surfactant stimulates the synthesis of prostaglandins by slices of human amnion at term and by a human amnion cell line, and these effects are partly dependent upon surfactant apoproteins. In this paper, methods are described for the purification of surfactant from human amniotic fluid and from post-mortem human lung. A procedure is described for the purification of surfactant protein SP-B from human amniotic fluid, and the sequence of 20 amino acids at the N-terminal has been determined.

Effect of lipid and protein fractions from fetal pulmonary surfactant on prostaglandin E production by a human amnion cell line.

Discs of amnion and choriodecidua prepared from women delivered at term were incubated with and without surfactant prepared from human amniotic fluid and the output of prostaglandin E (PGE) was estimated by radioimmunoassay. Surfactant stimulated the release of PGE in both tissues. The stimulatory effect was characterized further using cultured human amnion cells.

Surfactant stimulates prostaglandin E production in human amnion.

Discs of human amnion prepared from nine women delivered by elective caesarean section at term were incubated with and without purified human amniotic fluid surfactant (9 micrograms lipid P/ml), and the output of prostaglandin E (PGE) was estimated by radioimmunoassay. Surfactant stimulated the release of PGE from 3.8 (SD 2.

Effect of ischemia and reperfusion of pig skin flaps on epidermal glycogen metabolism.

Pedicled skin flaps in the pig have been used to investigate the effects of 3-h ischemia and reperfusion on the epidermal metabolism of glycogen and glucose. Epidermal glycogen content fell steadily at a rate of about 1.2 mumol of glucose-equivalents per g wet weight per h whereas the rate of glucose consumption declined from 1.

Glycogen metabolism in psoriatic epidermis and in regenerating epidermis.

The observation that the glycogen content of epidermis from psoriatic lesions and from regenerating wound epithelium is increased has been confirmed by quantitative estimation. In epidermis from psoriatic lesions, although the proportion of glycogen synthase in the I form is only about 5% of the total and similar to control values, total glycogen synthase activity is increased approximately 4-fold and hence glycogen synthase I activity is increased to the same extent. In contrast, total phosphorylase activity is only slightly increased and, since the proportion of the enzyme in the a form is reduced, phosphorylase a activity is similar to control values.

The effects of starvation and re-feeding on glycogen metabolism in mouse tail skin.

Although the glycogen content of mouse tail skin was decreased during starvation and was restored on re feeding, the proportion of glycogen synthase in the I form remained constant throughout at about 10% of the total. During the phase of net glycogen synthesis 1.5h after access to food was restored, the concentration of UDP glucose was markedly increased and the proportion of phosphorylase in the a form was significantly decreased.

The reversible detachment and deposition of surfactant and of pulmonary macrophages during bronchopulmonary lavage in the rat.

A procedure is described for carrying out repetitive bronchopulmonary lavage in the rat, in which a given volume of lavage fluid is introduced into the lungs from a reservoir and then withdrawn from the lungs back into the reservoir, the process being repeated a number of times. During this procedure there is a net release of endogenous surfactant and macrophages from the lungs. [14C] pulmonary surfactant was prepared from rats previously injected intravenously with [1-14C] palmitate, and pulmonary macrophages labelled with 85Sr were prepared from rats which had received by intratracheal injection a suspension of fused clay particles labelled with 85Sr.

The estimation of nitrate and nitrite in saliva and urine.

A method for the estimation of nitrate and nitrite is described in which nitrate is converted to nitrite by Klebsiella pneumoniae (UNF 9232) and nitrite is estimated by the Griess reaction before and after incubation. The method is suitable for the estimation of 1-25 nmol of each ion in body fluids, many samples can be handled simultaneously, and special apparatus is not required.

Glucose metabolism in experimental skin flaps.

The metabolism of glucose by rat abdominal skin flaps has been investigated at various times after flap elevation. Biopsies of flap skin taken during the first 3 days after flap elevation and incubated in vitro show a marked increase in glucose consumption and lactate production compared with normal skin. At the same time, flap tissue reserves of glucose and glycogen are lower than those of normal skin.

Hydrophobic proteins of lamellated osmiophilic bodies isolated from pig lung.

1. In addition to proteins that are insoluble in organic solvents, lamellated bodies isolated from pig lung and surfactant prepared from bronchopulmonary lavage fluid contain another group of proteins that are extracted together with lipid into the organic phase. 2.

The kinetics of macrophage and surfactant replacement in hamster lung following bronchopulmonary lavage.

The effects of bronchopulmonary lavage with isotonic NaCl have been investigated in the hamster, and methods are described for separating pulmonary surfactant from cells in lavage fluid and for the quantitative isolation of surfactant from lung. It has been shown that hamsters almost invariably survived a lavage which consisted of ten successive washes each of 2 ml saline. This procedure removed about 80 per cent.

Structural studies on lamellated osmiophilic bodies isolated from pig lung. 31P NMR results and water content.

1. Lamellated osmiophilic bodies are intracellular organelles in which pulmonary surfactant is stored prior to secretion. They contain about 85% phospholipid (per dry weight) and dipalmitoyl phosphatidylcholine is a major constituent, and although their ultrastructure is uncertain it is generally supposed that they resemble liposomes.

Glucose-6-phosphate dehydrogenase in lichen planus skin.

The apparent Michaelis constant (Km) for glucose-6-phosphate of the enzyme glucose-6-phosphate dehydrogenase has been measured in extracts prepared from biopsies of normal human skin and from both affected and apparently normal skin of patients with lichen planus. No differences of Km were found and starch gel electrophoresis of extracts from lichen planus lesions and normal controls showed similar patterns when stained for glucose-6-phosphate dehydrogenase activity. These results do not support the view that lichen planus is an inborn error of metabolism in which the structure of glucose-6-phosphate dehydrogenase of skin is affected.