Norman H. Leake

Control of Plasma Non-Esterified Fatty Acids in Pregnancy and the Puerperium.

Summary The amount and timing of glucose administered to fasting post partum women receiving intravenous insulin determines the amount and direction of change in plasma NEFA. Twenty-five grams of glucose inhibits the characteristic response of NEFA to insulin while half this dosage either enhances the insulin effect or causes secondary decrements in non-esterified fatty acid. These results suggest that the regulation of plasma NEFA is a complex function that may involve fatty acid synthesis, utilization and recycling as well as controlled release from fat depots.

Naturally occurring antibody to placental protein in human pregnancy

Antibody activity directed against human placental lactogen (HPL) preparations has been found primarily in postpartum patients. HPL is first detected in maternal serum at about the sixth week of gestation. 10% of women tested showed agglutinating ability against HPL-sensitized cells during pregnancy while more than 80% did post partum. An explanation for this is that the antigen HPL and its source, the placenta, have disappeared. Immunochemical studies indicate that the antibody molecule is either IgA or IgM and non-complement-fixing. The antibody activity of the human anti-HPL is inactivated by 2-mercaptoethanol. This treatment has been shown to destroy essentially all IgM antibody and around 50% of the IgA activity, but has little effect upon IgG antibody. Because of the lack of maternal antibody activity against the purest preparation of HPL, it is believed that the antibody is directed against trophoblastic antigens which have not been completely separated from earlier preparations of HPL.

Immunochemical comparison of human placental lactogen and placental proteins from other species.

Abstract A study of placental proteins from species other than man was undertaken as a possible aid in elucidating the role of HPL in man. Placental proteins from term placentas of the rhesus monkeys, rat, dog, pig, horse, sheep, rabbit, and cow were extracted by the same method, and chromatographic separation performed in the same manner as for HPL. Antiserum against HPL was produced in the rabbit and a modification of hemagglutination-inhibition was used to determine the degree of cross-reactivity with HPL in each chromatographic fraction, as related to the concentration of protein. The primary activity was found to occur in the third fraction from the G-100 Sephadex eluate in each species. The order of relationship to the human placental protein, as determined by immunologic reactivity, is as stated above. These results suggest a structural similarity, thus inferring a functional similarity between the placental proteins of the different species studied.

Plasma lipids in the early puerperium

Abstract Plasma lipids for nonpregnant and puerperal patients were resolved on silicic acid columns into triglyceride, phospholipid, and cholesterol ester fractions, and the esterified fatty acids in these fractions determined. Results showed that, with the exception of esterified cholesterol, puerperal values for the carboxyl esters increased during the 24 hours following delivery. In addition, a decrease was observed in these lipid components from the first through the fifth postpartum day which was primarily due to the triglycerides, though phospholipid and esterified cholesterol showed a slight drop. Impaired carbohydrate metabolism and its possible relation to insulin resistance was suggested as a factor explaining the hyperlipidemia of pregnancy and its decrease in the early puerperium.

Plasma nonesterified fatty acids in pregnancy: III. Further observations on regulation of plasma NEFA concentration by insulin and glucose

Abstract 1. The effect of various combinations of glucose and insulin on plasma NEFA concentrations were tested in normal pregnant, early puerperal, and nonpregnant subjects. 2. The responses observed in plasma NEFA were dependent upon the amount of glucose administered as well as the time of glucose loading in relation to that of insulin administration. Small amounts of glucose tended to enhance NEFA falls in plasma, while larger glucose dosages produced smaller changes or stabilized the fatty acid level. 3. The relative amounts of carbohydrate and insulin rather than the degree of hyperglycemia and hypophosphatemia appeared to determine the amount and direction of change in NEFA concentration. The experimental results are discussed in terms of the known factors determining NEFA oxidation, esterification, and release by adipose tissue. 4. Within a few days after the onset of labor the concentration of plasma NEFA is increased and its regulation is extremely labile as indicated by its sensitivity to experimental modification. This lability is not observed in the early puerperium. 5. Intravenous glucose tolerance data are not influenced by pregnancy in metabolically normal patients despite evidence of decreased reactivity to exogenous insulin.

LIPID COMPOSITION AND SYNTHESIS IN RAT LIVER DURING PREGNANCY AND THE PUERPERIUM.

Summary The composition and incorporation of acetate-1-C14 into liver lipids of non-pregnant, pregnant, and puerperal rats were determined. Results show that total cholesterol and phospholipid phosphorus in rat liver during pregnancy and the puerperium do not differ from those found in non-pregnant animals. However, the triglycerides from livers of puerperal animals were significantly higher than those found in either non-pregnant or pregnant rats. Incorporation of acetate-1-C14 into fatty acids and unsaponifiable substances by liver slices from pregnant rats was significantly greater than that observed for non-pregnant and puerperal rats. No differences were observed in the μmoles of acetate incorporated into the fatty acids of triglycerides and phospholipids. Possible factors related to the puerperal increase of triglycerides in the liver are discussed.

Effect of HPL and pregnancy on glucose uptake in rat adipose tissue.

The effects of pregnancy and human placental lactogen (HPL) upon net gas exchange and glucose uptake of adipose tissue were studied in rats. Tissue from pregnant rats showed a significantly greater response to insulin than that from nonpregnant animals. Basal glucose uptake of tissue from pregnant rats was significantly greater than that of nonpregnant animals. The activity of tissue from HPL-treated animals was equivalent to that of pregnant animals. Insulin-stimulated glucose uptake was significantly greater in tissue from both pregnant and HPL-treated rats. From the present and other data it is concluded that placental lactogen probably plays a significant role in the characteristic changes in carbohydrate and lipid metabolism seen during pregnancy.

Observations on the metabolic activity of a human placental fraction

Abstract 1. A placental fraction was extracted from human term placentas by the Raben technique for pituitary growth hormone. This preparation was administered to adult mongrel dogs and caused significant increases in plasma NEFA. A small increase in blood glucose was also observed. 2. No significant changes in free cholesterol, triglycerides, or lipid phosphorus were observed, but a tendency to lower cholesterol ester values was noted. No significant change occurred in the level of insulin-like activity of serum.

Carotene and Vitamin A in Pregnancy and the Early Puerperium.

Summary 1. Levels of carotene and vit. A in pregnant patients were shown to be significantly different from those found in nonpregnant and puerperal patients. 2. Differences in the means of carotene and vit. A between puerperal and non-pregnant patients were variable and it appeared that changes in carotene and vit. A following delivery are rapid and not significantly different from those found in the non-pregnant group. No differences were found in carotene and vit. A between postpartum days. 3. Diet was apparently not a factor influencing carotene and vit. A levels in this study. 4. Evidence was given supporting the inverse relationship between carotene and vit. A and it was suggested that the ratio (C/A) of these components may be a better parameter for detecting changes occurring in their metabolism. 5. The possible association of vit. A and carotene changes with changes in lipids during pregnancy was considered.

Amniotic fluid antibody titers and other prognostic parameters in erythroblastosis

Abstract A number of methods of determining the status of the infant in utero in erythroblastosis have been studied and compared to the outcome. The ratio of the per cent transmission at 520 mμ to that at 490 mμ, the Δ O . D . 450 , and the amniotic fluid antibody titer were found to be the most effective prognostic methods, in that order of significance. These is an improvement over the effectiveness of any single factor in prognostic ability when these factors are combined in a formula derived from multiple stepwise regression analyses of all possible combinations of factors studied. A discussion of possible reasons for the lack of significance of maternal antibody titer, and the significance of amniotic fluid antibody titer is undertaken.