Comparisons of chromium status in diabetic and normal men.
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Adult↗
Biomedical subjects
M B Rabinowitz
Publications and source records attributed to M B Rabinowitz.
Effect of food intake and fasting on gastrointestinal lead absorption in humans.
The effect of food intake versus brief fasting on gastrointestinal absorption of lead was measured in five healthy men who were living in a metabolic unit and eating constant lead diets. Lead absorpiton was assessed by the difference between dietary intake and output of 1) lead tracers composed of nonradioactive isotopes which were ingested as a single dose either with food or during a 16-hr fast, 2) lead tracers ingested with meals for relatively long periods (2 to 124 days), and 3) total led in ingested foods. Absorption estimated by 1) was confirmed by increments in tracer concentrations in blood. Lead tracers were given as nitrate, cysteine complex, or sulfide. Absorption was 10.3 +/- 2.2% (SD) for food lead; 8.2 +/- 2.8% for tracers ingested with food; and 35 +/- 13% (P < 0.01) percent for tracers ingested without food. The increased absorption of lead when ingested without food should be considered when the hazards of exposure to lead are determined.
Adult↗
Magnitude of lead intake from respiration by normal man.
Lead metabolism of five normal men was studied in a hospital metabolic unit in order to measure the daily intake of lead by respiration in urban adults. Subjects ingested a constant diet, and samples of blood, urine, feces, and diet were analyzed periodically for lead isotopic abundances by mass spectrometry. Three men were fed daily a stable isotope tracer of lead for 83 to 124 days in order to distinguish ingested from respired lead. Also, three men lived in rooms with filtered, low-lead air for 25 to 50 days in order to examine the response of blood lead levels to a change in airborne lead exposure. The quantity of respired lead intake was determined from the lead balance data, labeling of blood lead with a dietary lead tracer, and the response of blood lead levels and lead balances to exposure to low-lead air. The results indicate that these men absorbed a mean of 14 +/- 4 (S.D.) microgram/day of lead while exposed to the ambient levels of about 2 microgram/m3 of airborne lead. About twice this amount was absorbed from the diet.
Air↗
Kinetic analysis of lead metabolism in healthy humans.
The steady state kinetics of lead metabolism were studied in five healthy men with stable isotope tracers. Subjects lived in a metabolic unit and ate constant low lead diets. Their intake was supplemented each day with 79--204 mug of enriched lead-204 as nitrate which was ingested with meals for 1--124 days. The concentration and isotopic composition of lead was determined serially in blood, urine, feces, and diet and less commonly in hair, nails, sweat, bone, and alimentary tract secretions by isotopic dilution, mass spectrometric analysis. The data suggest a three compartmental model for lead metabolism. The first compartment encompasses blood and is 1.5--2.2 times larger than the blood mass. It contains approximately 1.7--2.0 mg of lead and has a mean life of 35 days. This pool is in direct communication with ingested lead, urinary lead, and pools two and three. The second compartment is largely composed of soft tissue, contains about 0.3--0.9 mg of lead, and has a mean life of approximately 40 days. This pool gives rise to lead in hair, nails, sweat, and salivary, gastric, pancreatic, and biliary secretions. Pool three resides primarily in the skeleton, contains the vast quantity of body lead, and has a very slow mean life. Bones appear to differ in their rates of lead turnover. Within the relatively small changes in blood lead observed in the present study, the transfer coefficients between the pools remained constant.
Adult↗
Lead metabolism in the normal human: stable isotope studies.
Kinetic and metabolic balance studies in a healthy man fed a diet normal in lead content and labeled with lead-204 indicated that approximately two-thirds of his assimilated lead was dietary in origin; the remainder was inhaled. Kinetic analysis shows that the isotopic data can be interpreted by a three-compartment model.
Bone and Bones↗
Dentine lead and child intelligence in Taiwan.
It is well known that lead is a developmental neurotoxin, but, because many factors influence a child's development, a safe level of lead for children is still not clear. In this study, personal lead exposure was assessed. A total of 940 deciduous teeth--mostly incisors--was collected from 764 children in grades 1-3 who attended 7 primary schools. Two of the primary schools were near smelters, 4 were in Taipei City, and 1 was located in a coastal village. Teachers were provided with a questionnaire about classroom performance, and 97% completed and returned the questionnaire to the laboratory. Parents were given a questionnaire about family background, pregnancy, and health history (92% returned). Dentine lead levels of shed incisors for children in Taipei City were higher than levels reported in Boston, i.e., mean (standard deviation) of 4.4 (3.5) versus 3.3 (2.5) micrograms/g, respectively (p less than .001). The lead values were significantly higher in children who attended school near a smelter than in children who attended school in Taipei City: 6.3 (3.3) (p less than .001). The mean lead levels in children who attended school in a coastal village was 5.1 (2.8). The ranges for all schools overlapped, which indicated that there were multiple lead sources. Intelligence scores from Raven's Colored Progressive Matrices Test were negatively correlated with lead levels, especially among girls and among children whose parents had less education. We adjusted for other risk factors--most notably parental education, which correlates inversely with lead levels--and found that the role of the lead term was lowered but not eliminated.
Air Pollutants↗
Effects of chromium and yeast supplements on carbohydrate and lipid metabolism in diabetic men.
Diabetes mellitus has been shown to develop as a consequence of chromium (Cr) deficiency in experimental animals and in humans sustained by prolonged total parenteral nutrition. Prior limited trials in humans had indicated that Cr supplements, in either inorganic or organic form, may improve carbohydrate utilization. We report here a clinical double-blind, random crossover trial of inorganic Cr trichloride, a brewer's yeast that contained Cr as glucose tolerance factor (GTF), a brewer's yeast extract without GTF, and a placebo. Forty-three outpatient diabetic men received three of these supplements for 4 mo each. Subgroups included 21 ketosis-prone men; 7 ketosis-resistant, nonobese men; and 15 ketosis-resistant obese men. Chromium levels were followed pre- and posttreatment in hair, red blood cells, plasma, and urine. Response of carbohydrate metabolism to treatment was assessed in terms of change in insulin requirements, fasting plasma glucose, plasma cholesterol, and triglycerides, as well as change in plasma glucose, glucagon, and insulin or C-peptide levels in response to a standard meal. In some men, these parameters were also measured after i.v. tolbutamide. Both the inorganic and organic oral Cr supplements increased measurable body pools of Cr in hair and red blood cells by about 25%. However, fasting plasma glucose and lipids and the glucose response to either the standard meal or to tolbutamide were not significantly altered by any of the treatments. Despite this lack of effect on carbohydrate levels, the ketosis-resistant subgroups demonstrated a significant increase in postprandial insulin after treatment with the brewer's yeast that contained GTF.
Blood Glucose↗
Early sensory-motor development and prenatal exposure to lead.
As part of a longitudinal study of the early developmental effects of exposure to lead, we administered the Bayley Scales of Infant Development at age 6 months to infants classified into three groups based on their umbilical cord blood lead levels ("low": mean = 1.8 micrograms/dl; "mid": mean = 6.5 micrograms/dl; "high": mean = 14.6 micrograms/dl). No infant had a cord blood lead level greater than 30 micrograms/dl, the level currently regarded as the upper limit of "normal" for young children. Multiple regression analyses indicated that high cord blood levels were associated with lower covariance-adjusted scores on the Mental Development Index. Scores on the Psychomotor Development Index were not significantly related to cord blood lead level. The level of lead in blood at 6 months of age was not associated with scores on either the Mental or Psychomotor Development Index. These data are compatible with the hypothesis that low levels of lead delivered transplacentally are toxic to infants.
Child Development↗