Patricia A. Pleban

Trace elements in human seminal plasma and spermatozoa

Methodologies for the analysis of cadmium, copper, iron, lead, selenium and zinc in human seminal plasma and spermatozoa have been developed. Analyses were made directly in a dilution of seminal plasma or nitric acid digest of lyophilized cells using Zeeman-effect atomic absorption spectroscopy. Within-run coefficients of variation (CVs) for pooled specimens ranged from 0.5% to 9%. Between-run CVs ranged from 4% to 13%. Analysis of a seminal plasma specimen at 1/2, 1, 1 1/2, 3 1/2 and 5 hours post emission indicated that no change in seminal plasma trace element concentrations occurred on standing in contact with spermatozoa. Trace element concentrations were determined in specimens from patients undergoing infertility studies.

Effect of lactose on mineral absorption in preterm infants

To determine whether a reduction of dietary lactose affects mineral absorption in preterm infants, a controlled, randomized, 72-hour balance study was conducted with very low birth weight infants (birth weights less than 1400 gm) fed Similac Special Care formula with a 50:50 carbohydrate blend of glucose polymers and lactose (n = 8) or a nearly identical formula with 100% carbohydrate as lactose (n = 10). The studies were conducted after at least 3 consecutive days of full oral feeds at a mean age of approximately 23 days. There was no difference between groups in percentage of apparent absorption of calcium, phosphorus, magnesium, zinc, copper, or manganese. Retention of these nutrients was similar to or greater than that which occurs in utero. Calcium absorption was 75% of intake. These results indicate that reducing the lactose content of premature-infant formulas to 50% of the carbohydrate does not impair mineral absorption.

Residential exposure to chromium waste--urine biological monitoring in conjunction with environmental exposure monitoring.

To determine whether a population living on or adjacent to four sites of chromate production waste was measurably exposed to environmental chromium, spot samples of urine were collected along with wipe samples of household dust and lifestyle/activity interview data. Findings were compared to those from a control population in two communities with no significant chromium use or waste sites. Urine samples were collected and analyzed, employing measures to minimize background chromium contamination. The average Cr mass in dust was 3.7 times that in control houses. The mean creatinine-corrected urine Cr (Cr/c) level of the exposed subgroup residing in households in the 75th percentile of Cr mass in wipe samples was significantly greater than that of the control population. This subgroup was primarily located at a single exposure location. Using lifestyle/activity data, significantly elevated Cr/c urine levels were identified in other exposed subgroups defined by employment location and by outside play time. These data show an association between elevated exposure to chromium in household dust and elevated urine levels of chromium, consistent with residential exposure to chromate production waste. These data also suggest an association between chromium exposure and activities outside the home which are consistent with exposure to chromate production waste.

Magnesium, zinc and copper in plasma and blood cellular components in children with IDDM

The levels of magnesium (Mg), zinc (Zn) and copper (Cu) in the plasma, erythrocytes (RBC) and polymorphonuclear (PMN) and lymphocyte (L), leukocytes (WBC) of 45 diabetic children were compared to those of 12 normal children and were related to the diabetic control via HbA1 and fasting blood sugar (FBS) assessments. Mineral levels were determined via Zeeman-effect atomic absorption spectrophotometry following separation of plasma, RBC, and WBC fractions (PMN vs. M). ANOVA (four-way, blood components, by two-way, diabetic vs. normal children) was significant for Mg only (F = 4.60, P < 0.004). Plasma Mg and M-WBC Mg were significantly lower in children with diabetes (780 +/- 16 vs. 860 +/- 29 mumol/l and 519 +/- 33 vs. 866 +/- 86 micrograms/10(10) cells, respectively). RBC Zn was significantly lower in diabetic youngsters by t-test (0.48 +/- 0.012 vs. 0.57 +/- 0.046 per mumol/g Hgb, t = 2.79, P < 0.004), but the ANOVA for Zn was not significant. Cu level differences were not significant. HbA1 was predicted only by PMN-WBC Mg (F = 8.78, P < 0.04) and FBS by none. In conclusion, the mineral status of these diabetic children was altered in regard to Mg, but was mainly independent of diabetic control.

Experimental and theoretical evidence for cyclic selenurane formation during selenomethionine oxidation.

The oxidation products of selenomethionine (SeMet) have been studied via experimental (77)Se NMR and theoretical (77)Se chemical shifts. Four signals are observed: a diastereomeric pair of selenoxides at 840 ppm and two unidentified resonances at 703 and 716 ppm. Theoretical DeltaG and chemical shifts suggest the 703 and 716 ppm resonances correspond to hypervalent selenium heterocycles, called selenuranes, formed by reaction with the amine or acid group of the amino acid and the selenoxide. To identify which of these selenuranes is formed, the amine and acid groups were individually protected. The N-formyl SeMet formed only the selenoxide pair at 840 ppm. The oxidized SeMet methyl ester produced signals at 703 and 716 ppm which are assigned as the Se-N selenurane.

2 Trace element metabolism in the fetus and neonate

Summary The effects of trace metal nutrition on the fetus and neonate have been described. Since very little research has been done with the human fetus and neonate, much of our knowledge must be extrapolated from animal studies. In addition, most of the work centres around the effects of copper and zinc nutrition. Nutritional requirements (when known) for both enteral and total parenteral feeding of certain trace metals, as well as the bioavailability, have been discussed. Finally, methods of assessment of trace metal nutritional status have been discussed. These include direct measurement of metal concentrations and determination of biochemical indicators, such as metal-dependent enzyme activities—both of which are static indicators of nutritional status, and functional assessment of nutritional status which is a dynamic measure of trace metal nutrition and includes tests measuring the effects of metal nutrition on the function of cells, tissues, organs, and the host in general.

Kinetic nephelometric determination of transthyretin and retinol-binding protein in neonatal serum

We have developed a kinetic immunonephelometric method for the determination of retinol-binding protein and modified the method of Jacob et al (Clin Chem 1983; 29: 564) for the determination of transthyretin (prealbumin) in neonatal serum specimens from small, premature infants. The methodologies allow detection of 17.5 mg/l transthyretin and 1.7 mg/l retinol-binding protein in 25 microliter of serum. Between-run precision studies using pooled neonatal serum gave CV values of 3% and 5-6% for transthyretin and retinol-binding protein, respectively. Results obtained for neonatal specimens using this method agreed well with those obtained for the same specimens using radial immunodiffusion. Mean (SD) serum concentrations for 39 neonatal specimens were 100.4 (46.6) and 26.3 (10.8) mg/l for transthyretin and retinol-binding protein, respectively.

Cadmium, Copper, Lead, Manganese, and Selenium Levels, and Glutathione Peroxidase Activity in Human Kidney Cortex

Abstract Cadmium, copper, lead, manganese, and selenium concentrations and glutathione peroxidase (EC 1.11.1.19) activity have been determined in human kidney cortex specimens obtained at autopsy. Trace metal concentrations for each specimen were determined in the same digest, while glutathione peroxidase activity was assayed in tissue collected at a site adjacent to that selected for the trace metal determinations. Glutathione peroxidase activities were determined with two substrates, hydrogen peroxide and t-butylhydroperoxide. The effects of age, smoking history, sex, race, and blood pressure on kidney cortex trace metal levels and glutathione peroxidase activity were investigated. Mean kidney cortex cadmium concentration was found to be significantly higher in smokers than in nonsmokers (p=0.010). In addition, the mean kidney cortex lead concentration of hypertensive individuals was found to be significantly higher than that of non-hypertensive individuals (p=0.017), Glutathione peroxidase activities u...

Change in Hen Sciatic Nerve Calcium after a Single Oral Dose of Tri-o-tolyl Phosphate12

Six trace elements were monitored in neural tissue homogenates from White Leghorn hens orally dosed with tri-o-tolyl phosphate (TOTP) or tri-m-tolyl phosphate (TMTP) (200 mg/kg). Treated birds were monitored daily for development of delayed neurotoxicity, and concentrations of calcium, copper, iron, magnesium, manganese, and zinc were measured with atomic absorption spectroscopy at the time of maximal locomotor impairment (27–35 days postdosing). TOTP-treated birds manifested motor deficit by 15 days postdosing, while hens administered TMTP exhibited no signs of delayed neurotoxicity. Total calcium content in the sciatic nerve homogenates from TOTP-dosed hens was significantly less (P < 0.05) at the time of maximal locomotor impairment, while no shifts in the other trace elements were found. Therefore, the ortho isomer of tritolylphosphate ilicited symptoms of delayed neurotoxicity in the hen (i.e., organophosphorus ester-induced delayed neurotoxicity or OPIDN) and caused a decrease in total calcium content in the sciatic nerve homogenates, in contrast to effects of the meta isomer. Analysis of neural homogenates at time of maximal locomotor impairment reflected secondary events in the degradative processes, since the initial assault of TOTP happens early after administration. Therefore, at fully developed OPIDN alteration of calcium balance in sciatic nerves is an indicator of axonopathy in a degenerated nerve following chemical injury.