Richard L. Burt

Plasma nonesterified fatty acids in pregnancy

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.

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.

Physiologic changes in plasma chromium of normal and pregnant women: Effect of a glucose load

Plasma chromium (Cr) concentrations were determined for healthy nonpregnant women and also for women in late pregnancy of similar ages. Plasma Cr was found to be significantly lower in the fasting fireanant subjects (2.97 ± 0.11 standard error of the mean [S.E.M]) than in normal subjects (4.70 ± 0.15 S.E.M.). An intravenous glucose load (25 Gm.) produced a prompt and sustained fall in plasma Cr in normal women but it failed to change the plasma Cr level of pregnant subjects. A similar fall in plasma chromium was also observed in nonpregnant subjects after an oral glucose load. The plasma Cr response was specific in that plasma copper and iron were unaltered by the glucose load. The mean rate of glucose assimilation after intravenous glucose loading was nearly identical for the pregnant and nonpregnant subjects. Plasma inorganic phosphate decreased in both pregnant and nonpregnant subjects but the fall was diminished in pregnancy. Fasting plasma immunoreactive insulin (IRI) was not significantly different for pregnant and nonpregnant subjects, but the plasma IRI response to a glucose load was greatly increased in pregnancy. The significance of the plasma Cr changes and the other experimental results are discussed in relation to the known altered carbohydrate metabolism of pregnancy.

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.

Renal excretion of trace elements: chromium and copper.

Summary The ingestion by normal adults of a standard oral glucose load (75 g) resulted in a significant decrease of the fasting rate of urinary excretion of the trace metal chromium. This effect was not accompanied by any significant parallel change in GFR. Copper excretion rate was not significantly changed by the glucose load. In contrast with the effect of a glucose load, diuresis, induced by a water load, increased the excretion rate of both chromium and copper by more than 100%. The increases in metal excretion with diuresis were not attributable to increased GFR. Observations on the renal excretion of chromium and copper in the dog showed that tubular reabsorption of chromium and copper was greater than 98% in normal fasting conditions. In dogs receiving intravenous infusions of hypotonic saline and of vasopressin, a marked correlation was obtained between urine flow rate, the chromium and copper excretion rates, and also the fraction of the filtered loads of the metals excreted. However, tubular reabsorption of chromium and copper was greater than 97% even at maximal urine flow rates. These observations suggest that the kidney of both man and dog may possess an active tubular reabsorptive capacity for chromium and copper. We are grateful to Professor J. Maxwell Little for helpful discussions and suggestions, and we thank W. L. Secrest for expert technical assistance. These studies were supported in part by NIH Grant No. RR-5404.

Cerebral venous thrombosis in the puerperium: Report of two cases with necropsy findings

Abstract 1. 1. Two cases of primary cerebral venous thrombosis in the puerperium are reported. 2. 2. The clinical features and treatment of this condition are briefly reviewed.

THE EFFECT OF INSULIN AND GLUCOSE ON PLASMA LIPIDS DURING PREGNANCY AND THE PUERPERIUM.

Summary 1. Evidence was presented that confirmed the hyperlipidemia of pregnancy and showed that with the exception of esterified cholesterol, significant decrements occurred in the fasting levels of plasma lipids by the fourth postpartum day. 2. The mean changes in plasma levels of triglycerides, free cholesterol, and lipid phosphorus in nonpregnant, pregnant, and puerperal subjects differed significantly in their responses to insulin and/or glucose. 3. Mean changes in cholesterol ester were not attributed to the differential response of the 3 groups to insulin and glucose, but appeared to be related to the free cholesterol levels. 4. Analysis of variance revealed that with the exception of lipid phosphorus levels, the mean changes in the plasma lipids were attributable to factors other than the group × treatment interaction. 5. Glucose metabolism during pregnancy was altered in favor of cholesterolgenesis, and it was indicated this difference was due to impaired carbohydrate metabolism through the dissociation of the effect of insulin on extrahepatic tissue. 6. The relative amounts of insulin and glucose were reflected in the plasma levels of free cholesterol in pregnant and puerperal subjects.

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.