Glycosylated hemoglobin levels reflect glucose homeostasis over the preceding months. Many investigators have reported levels of glycosylated hemoglobin in diabetics and have noted a strong correlation of these levels with lipids and lipoproteins, but not with HDL cholesterol. We report here the first population-based study of the predominant fraction of glycosylated hemoglobin, HbA1, and its correlates in nondiabetics. In 558 euglycemic adults (fasting plasma glucose less than 140 mg/dl) aged 40 to 79 years who had no history of diabetes, HbA1 was normally distributed, was unrelated to age, and was correlated with fasting plasma glucose in men and women and with obesity in women. After adjusting for age and obesity, HbA1 was significantly correlated with total plasma cholesterol and LDL cholesterol in both sexes and with total plasma triglyceride and VLDL cholesterol in men. HDL cholesterol was not significantly associated with HbA1 in men or women. These associations are similar, although weaker, than those reported in most studies of diabetics. The finding that the association of glycosylated hemoglobin with lipids and lipoproteins extends throughout the normal range of blood sugar suggests that this association may be relevant to both the excess risk of ischemic heart disease in diabetics and in nondiabetics with higher levels of fasting plasma glucose.

Aged↗

PubMedDate not supplied

The weak binding reaction between folate and human serum proteins.

New evidence is presented that folic acid in serum binds with low affinity to major serum proteins. This low affinity binding is distinct from the high affinity binding by folate binding protein (FBP), a minor protein which is known to occur in serum with great quantitative variability. These conclusions are based on results obtained by equilibrium dialysis of serum containing only negligible amounts of FBP. At 4 degrees, the equilibrium value of the ratio of bound to free folate was approximately 0.81 and remained the same even wth up to 1,000 times greater than normal folic acid concentrations; however, with higher concentrations the ratio decreased progressively. These results are predicted by the laws of mass equilibria for a binding system with low ligand concentration vis-a-vis high binder concentration and low affinity between the reactants. A rough estimate of the mean affinity constant K governing this weak folate interaction with serum proteins yielded a value of 1.12 +/- 0.13 X 10(3) M-1.

Blood Proteins↗

PubMedDate not supplied

Blood lead levels in San Diego policemen.

Blood lead levels were measured by atomic absorption spectrophotometry in 86 San Diego policemen to see if they would reflect the known high atmospheric lead levels in San Diego. The mean blood lead for the entire group was 27.0 microgram per dl, a level very similar to that found in the general population of other cities. Work exposure to heavy traffic, area of residence, work shift and smoking did not significantly influence blood lead. Thus, an ambient atmospheric lead load ranging from 2 to 5 microgram per cubic m does not demonstrably cause higher blood lead levels in persons exposed to such air. Surprisingly, the youngest group, 21 to 25 years, had the highest mean (32.2 microgram per dl) while the oldest, 46 to 55 years, had the lowest mean (20.9 microgram per dl), a difference statistically highly significant. However, length of work as a policeman per se did not influence blood lead levels. Exposure to other known high-risk factors (hobbies, ceramics, old dwellings) was associated with higher levels (mean 30.6 microgram per dl).

Adult↗

PubMedDate not supplied

A long-term study of the absorption of large oral doses of folic acid.

Large daily doses of oral folic acid ranging from 25 to 1,000 mg and totalling between 1,875 and 16,000 mg per course of treatment were well tolerated without any evidence of toxic effects by four hyperuricemic men of the ages of 26, 38, 46 and 50 years. The minimum folate absorption in the gut as measured by urinary excretion ranged from 10.1 to 45.7 percent. The percentage of absorption within a give patient remained similar in successive courses and there was no evidence of saturation of the absorption process related to dose or time. The pattern of urinary excretion of folates did not indicate that appreciable fractions relative to the large folate doses were retained by the patients. Serum, erythrocyte, and urine folates returned to pretreatment levels within 120 days after treatment. These findings suggest that the folate stores of the body do not expand by orders of magnitude even when megadoses of folates are absorbed in the gut. The rise of the folate levels in erythrocytes was gradual and continuous during treatment and is best explained by postulating that incorporation of folate into red cell takes place mostly at the precursor and reticulocyte stages. The decrease of erythrocyte folate values seen 40 to 66 days after folate treatment indicates that the folate content of erythrocytes diminishes during their life span.

Adult↗

PubMedDate not supplied

Theoretical analysis of ligand-binder complex formation: partial equilibrium and incubation time.

This report presents a theoretical model of the rate at which complex formation approaches equilibrium in competitive binding systems while ligand concentration varies. Three commonly encountered systems are examined in which binder concentrations (q) are fixed at 0.5/K, 3/K and 50/K, respectively. Our analysis of the incubation time for any particular fraction of reaction completeness shows that longest incubation times occur with the lowest ligand concentrations when q = 0.5/K. However, in systems where q = 3/K and q = 50/K, the longest incubation times correspond not to lowest ligand concentrations but to those approximating the concentration of binder. It is concluded that empirical determination of minimal incubation times for these latter two assay systems should be performed with ligand and binder in approximately equal concentrations.

Kinetics↗