Gallium nitrate for acute treatment of cancer-related hypercalcemia: clinicopharmacological and dose response analysis.

Current treatment of cancer-related hypercalcemia is limited by agents of limited effectiveness or excessive toxicity. Gallium nitrate is a new drug which both inhibits bone resorption and increases calcium content of bone. We have now treated 39 episodes of hypercalcemia with gallium nitrate administered as a continuous i.v. infusion for 5-7 days at 3 daily dose levels (100 and 200 mg/m2, and 50 mg/m2 by brief infusion followed by 150 mg/m2). Nadir calcium values were significantly lower (9.2 +/- 1.5 mg/dl) for patients who received the highest dose relative to patients who received the lowest dose (10.5 +/- 1.6 mg/dl, P less than 0.001). While the actual percentage of patients who achieved normocalcemia was higher at the highest dose relative to the lowest dose (86 versus 60%), this difference was not statistically significant. Mean serum concentration of inorganic phosphorous declined significantly for all patients from 2.9 +/- 0.86 mg/dl at base line to 1.8 +/- 0.66 mg/dl (P less than 0.001). Pharmacokinetic studies suggested that a threshold plasma gallium concentration of approximately 1 microgram/ml must be attained to achieve acute normalization of elevated serum calcium levels. Steady-state plasma gallium levels were attained after 48 h; there was no evidence of drug accumulation in plasma after 2 days. Effects on serum creatinine concentration were negligible, and there were no other toxic reactions. These data confirm preclinical experiments which suggested that inhibition of bone resorption by gallium nitrate is dependent upon the dose and duration of drug exposure. We conclude that gallium nitrate is effective treatment for cancer-related hypercalcemia. The drug is now being evaluated against standard treatment in a randomized, double-blind trial.

Pharmacokinetics of cis-diamminedichloroplatinum(II) after administration in hypertonic saline.

Nephrotoxicity, the dose-limiting toxicity of cis-diamminedichloroplatinum(II) (CDDP), is ameliorated when administered in hypertonic saline with normal saline hydration. To determine whether the diminished nephrotoxicity is associated with alteration of the pharmacokinetics of CDDP, we examined the pharmacokinetics of free and total platinum, platinum renal excretion, and urine electrolytes in patients given CDDP in hypertonic saline and in patients given CDDP in a conventional manner. The pharmacokinetics of free and total platinum for equal doses of CDDP were similar regardless of the vehicle of administration and the method of hydration. CDDP given in a vehicle of high chloride concentration with normal saline hydration resulted in a statistically significant increase in both urine volume and chloruresis compared to the conventional regimen. The decreased nephrotoxicity associated with administration of CDDP in hypertonic saline with saline diuresis may be related to increased chloruresis, urinary volume, or a combination of both, but did not appear to be related to an alteration in the pharmacokinetics.

Gallium nitrate inhibits accelerated bone turnover in patients with bone metastases.

Bone metastases are a major source of morbidity in patients with cancer. Previously, we found that gallium nitrate was a highly effective treatment for cancer-related hypercalcemia. Laboratory studies have shown that this drug inhibits bone resorption in vitro and that short-term treatment in vivo increases the calcium content of bone. We evaluated the clinical effects of gallium nitrate on biochemical parameters of increased bone turnover in 22 patients with bone metastases. Treatment with gallium nitrate for five to seven days caused a median reduction in 24-hour urinary calcium excretion of 66% relative to baseline measurements (P less than .01). Hydroxyproline (OHP) excretion was also significantly reduced (P less than .01). The greatest reduction in hydroxyprolinuria occurred in patients with high baseline excretion. Ionized serum calcium and serum phosphorous declined significantly after treatment (P less than .01 for each). Serum immunoreactive parathyroid hormone (PTH) increased significantly (P less than .01), as did serum levels of 1,25 (OH)2-vitamin D3 (P less than .05). Urinary phosphorous excretion and serum levels of 25-OH-vitamin D3 were not significantly changed. No major toxic reactions occurred as a result of this treatment. These results indicate that gallium nitrate significantly reduces biochemical parameters associated with accelerated bone turnover and that this agent may be useful for preventing pathologic conditions associated with bone metastases.

Comparison of methods of evaluating nephrotoxicity of cis-platinum.

The urinary excretion of leucine aminopeptidase (LAP), N-acetyl-beta-glucosaminidase (NAG), and beta 2-microglobulin was measured in 12 cancer patients receiving cis-platinum to evaluate the sensitivity of these indices for renal tubular damage. NAG and LAP excretion rose markedly in all patients, and beta 2-microglobulin rose in 11. Seven of the 9 patients who had received cis-platinum 6 wk before the study had prestudy dose elevations of one or more of these indices. We conclude that these urinary proteins are sensitive indicators of proximal renal tubular injury and may provide greater sensitivity for comparison of the nephrotoxic potential of future platinum analogs or for assessing the efficacy of regimens designed to protect the kidney from platinum nephrotoxicity than other measurements. The persistence of high excretion vales for these indices 6 wk after a dose demonstrates the persistent renal injury by cis-platinum.

Effects of repletion with zinc and other micronutrients on neuropsychologic performance and growth of Chinese children.

The knowledge that zinc is essential for growth and neuropsychologic performance and a report of zinc-responsive stunting in Chinese children prompted this project. This article summarizes findings from a 10-wk, double-blind, controlled trial of zinc repletion in 740 urban, 6-9-y-old first graders from low-income families in Chongqing, Qingdao, and Shanghai, People's Republic of China. Treatments were 20 mg Zn alone (Z), 20 mg Zn with micronutrients (ZM), and micronutrients alone (M). The M mixture was based on National Research Council guidelines. Nutrients that might interfere with zinc retention were excluded or given in lower amounts. Main outcomes were changes in neuropsychologic performance and knee height. Hemoglobin, serum ferritin, plasma and hair zinc, and whole blood and hair lead were also measured. Anemia was not common, and serum ferritin concentrations were usually within the range of normal. Mean baseline plasma zinc concentrations were marginal in children from Chongqing and Qingdao and normal in children from Shanghai. After treatment with ZM or M plasma zinc increased. Hair zinc tended to decrease after all treatments. Mean baseline whole blood lead concentrations were slightly below the limit considered excessive for children by the US Centers for Disease Control and Prevention. Neuropsychologic performance and growth were most improved after treatment with ZM. These findings were consistent with the presence of zinc and other micronutrient deficiencies.

Zinc deficiency and oxidative stress in the retina of pigmented rats.

PURPOSE: To determine the effect of moderate zinc deficiency on antioxidant defenses and measures of oxidative stress in the retina and retinal pigment epithelium (RPE) of Brown Norway Rats. METHODS: Twenty-four rats were housed individually and divided into three groups of 8 rats each. Group 1 was fed ad libitum a semipurified control diet formulated to contain 50 parts per million [ppm] total zinc; group 2 was fed ad libitum an identical diet but containing 5 ppm total zinc; and group 3 was pair-fed the control diet but restricted in amount to that consumed by group 2. Food intake was measured daily and the rats weighed weekly. After 6 weeks, the rats were killed and the following measurements were made: serum zinc, serum alkaline phosphatase, retinal zinc, RPE-choroid zinc, RPE-choroid catalase, liver metallothionein (MT), retinal MT, RPE-choroid MT, retinal catalase, and retinal thiobarbituric reactive substances (TBARS). RESULTS: The following showed statistically significant differences between groups 2 and 3, respectively: serum Zn (1216 micro/l versus 1555 microg/l, P < or = 0.01), serum alkaline phosphatase (3.75 U/mg versus 5.10 U/mg, P < or = 0.05), liver MT (4.3 microg/mg protein versus 16.7 microg/mg, P < or = 0.0001), RPE-choroid MT (1.3 microg/mg protein versus 2.2 microg/mg, P < or = 0.02), retinal MT (0.85 microg/mg protein versus 2.8 microg/mg, P < or = 0.05), and retinal TBARS (6.2 nM/mg protein versus 2.2 nM/mg, P < or = 0.05). CONCLUSIONS: The results show that retinal MT and RPE MT concentrations are very sensitive to intake of dietary zinc. The increase in retinal TBARS in group 2 indicates that moderate zinc deficiency increases oxidative stress to the retina. The results also suggest that MT is protective against lipid peroxidation of retinal membranes.

Metallic wear in failed titanium-alloy total hip replacements. A histological and quantitative analysis.

We conducted extensive histological examination of the tissues that were adjacent to the prosthesis in nine hips that had a failed total arthroplasty. The prostheses were composed of titanium alloy (Ti-6Al-4V) and ultra-high molecular weight polyethylene. The average time that the prosthesis had been in place in the tissue was 33.5 months (range, eleven to fifty-seven months). Seven arthroplasties were revised because of aseptic loosening and two, for infection. In eight hips cement had been used and in one (that had a porous-coated implant for fifty-two months) no cement had been utilized. Intense histiocytic and plasma-cell reaction was noted in the pseudocapsular tissue. There was copious metallic staining of the lining cells. Polyethylene debris and particles of cement with concomitant giant-cell reaction were present in five hips. Atomic absorption spectrophotometry revealed values for titanium of fifty-sic to 3700 micrograms per gram of dry tissue (average, 1047 micrograms per gram; normal, zero microgram per gram), for aluminum of 2.1 to 396 micrograms per gram (average, 115 micrograms per gram; normal, zero micrograms per gram), and for vanadium of 2.9 to 220 micrograms per gram (average, sixty-seven micrograms per gram; normal, 1.2 micrograms per gram). The highest values were found in the hip in which surgical revision was performed at fifty-seven months. The concentrations of the three elements in the soft tissues were similar to those in the metal of the prostheses. The factors to which failure was attributed were: vertical orientation of the acetabular component (five hips), poor cementing technique on the femoral side (three hips), infection (two hips), and separation of a sintered pad made of pure titanium (one hip). A femoral component that is made of titanium alloy can undergo severe wear of the surface and on the stem, where it is loose, with liberation of potentially toxic local concentrations of metal debris into the surrounding tissues. It may contribute to infection and loosening.

Chromium content of total parenteral nutrition solutions.

Chromium (Cr) present as contaminant was analyzed by flameless atomic absorption spectrometry in a variety of commercially produced solutions and additives commonly used in total parenteral nutrition (TPN) formulas. Total Cr likely to be administered unintentionally per day was estimated both by summing the Cr in appropriate volumes of each solution required for preparation of standard TPN formulas and by analyzing complete TPN solutions. Storage of TPN solutions in plastic bags for 14 days did not affect Cr concentrations. The amounts ranged from 2.4 to 8.1 micrograms/day for a high glucose formula and 2.6 to 10.5 micrograms for a high lipid formula. Amino acid solutions, especially when containing phosphate, or with phosphate salt additives and with lipid emulsions accounted for approximately 85 to 90% of the Cr found.

Manganese content of large-volume parenteral solutions and of nutrient additives.

Manganese (Mn) was analyzed by flameless atomic absorption spectrophotometry in a variety of commercially produced solutions and additives commonly used in total parenteral nutrition (TPN). The amount of Mn in preparations tested varied among manufacturers and among lots. It was generally present in very small amounts with amino acid preparations supplying the major portion in the TPN formulas. Among amino acid solutions, Aminosyn 10% had the highest Mn content (5.2-17.0 micrograms/liter) with Veinamine 8%, FreAmine II, 8.5%, Travasol 10%, and Nephramine having less than 6.7 micrograms/liter. Other large volume parenterals contained appreciably less Mn, eg, Dextrose 50% had 0.64-2.5 micrograms/liter. Some of the additives were high in Mn, eg, potassium phosphate--280 micrograms/liter, magnesium sulfate 50%--up to 225 micrograms/liter, and Berocca C--245.8 micrograms/liter but their actual contributions to daily TPN intake was no more than 3.3 micrograms. The calculated Mn content in TPN formulas with varying source materials ranged from 8.07-21.75 micrograms per total daily volume. These values agreed with those obtained from analysis of actual TPN solutions. The values for 10% Intralipid and 20% Liposyn were 0.5 and 3.0 micrograms/liter, respectively.

Iron exacerbates aniline-associated splenic toxicity.

Our earlier studies have shown that aniline exposure in rats causes time- and dose-dependent accumulation of iron in the spleen, which may exacerbate aniline splenotoxicity by catalyzing free-radical reactions. The present studies were conducted to test whether aniline-induced splenic toxicity could be potentiated by iron overload. For 30 d male Sprague-Dawley rats received the following treatments: 0.5 mmol/kg/d aniline hydrochloride (AH) by gavage (AH group); 3% carbonyl iron-supplemented diet (IR group); 0.5 mmol/kg/d AH by gavage and iron-supplemented diet (AH + IR group); or no treatments (controls). Treatment-related significant increases in total iron, low molecular weight chelatable iron, lipid peroxidation, and protein oxidation were observed in the spleens of all the groups compared to control. However, these changes were much greater in the combined AH + IR group. The aniline-induced morphological changes in the spleen were consistent with our earlier observations, but were more pronounced in the AH + IR group. The increased toxicity, as evident from greater oxidative stress and morphological changes in the AH + IR group, suggests that iron potentiates the splenic toxicity of aniline.

Influence of zinc on selected cellular functions of cultured human retinal pigment epithelium.

Zinc is a necessary micronutrient, usually abundant in human RPE. Our study was undertaken to determine the effects of short-term, zinc deficiency on human retinal pigment epithelium (RPE) using a culture model of fetal human RPE cells. Human fetal RPE cells were isolated and cultured in Coon's modified Ham's F-12 medium. For zinc depletion studies, cells were cultured for 1 week in Chelex-treated Dulbecco's modified Eagle's medium containing low (0.25 microM) or physiologic (11 microM) total zinc concentrations as determined by flame atomic absorption spectroscopy. Protein synthesis was determined by incorporation of 35S-cysteine/methionine and labeled proteins analysed by polyacrylamide gel electrophoresis. Several cell parameters and enzymes were significantly reduced below control when cultured in low zinc: zinc content (40%), proliferation (63%), protein/well (50%), catalase activity (68%), alkaline phosphatase activity (61%), alpha-mannosidase activity (68%), and metallothionein (82%). No statistically significant decline was seen in acid phosphatase activity, superoxide dismutase activity, glutathione peroxidase activity and dexamethasone induction of metallothionein. Zinc repletion (100 microM, 1 h) increased catalase and alpha-mannosidase activities from 32% and 33% of control to 75% and 73%, respectively. Cycloheximide did not inhibit this short-term zinc-induced repletion of catalase or alpha-mannosidase. Protein synthesis in low zinc medium was depressed, but not significantly, as shown by incorporation of radiolabeled 35S-cysteine/methionine into newly synthesized proteins. The effects of zinc deficiency in cultured human RPE are selective. Adequate intracellular zinc was required for maximal activity of some enzymes. The dependence of catalase activity on zinc was not predicted and may help explain the observed decline in catalase activity seen with age in RPE. Our model of zinc deficiency should prove useful in elucidating the complex effects of zinc deficiency and repletion in human RPE.

A hydrogen-peroxide digestion system for tissue trace-metal analysis.

Tissue digestion prior to analysis for trace metals is usually carried out with strong acids. Nitric acid, alone or in combination with perchloric acid, is most commonly used. In addition to the laborious acid washing of all glassware prior to use, the digestion necessitates exposure to potential environmental contamination. Use of perchloric acid mandates a specially constructed hood with facilities for washing to remove acid deposits.A simple digestion procedure using 30% hydrogen peroxide in polyethylene vials in an oven at approximately 75°C has been previously described for the measurement of zinc in tissues using flame or flameless atomic absorption spectrophotometry and of selenium in liver by flameless atomic absorption. Readings for reagent blanks were insignificant. The technique has been further developed with a reduction in digestion time using 50% H2O2. Analysis of liver has been extended to include copper, manganese, and arsenic. Although the level of arsenic present was too low to be detected, 50 and 100 ng of this element added to the liver powder was completely recovered.The digest obtained when dissolved in appropriate solvent is suitable for analysis for multiple trace metals.

Polyatomics in zinc isotope ratio analysis of plasma samples by inductively coupled plasma-mass spectrometry and applicability of nonextracted samples for zinc kinetics.

Inductively coupled plasma-mass spectrometry (ICP-MS) is a powerful tool for both quantitative multielement analyses of inorganic elements and measurement of isotope ratios (IRs). The main disadvantage of this technique is the existence of polyatomic isobaric interferences at some key masses. Zinc has been investigated for such potential interferences in serum or plasma. The Zn isotopes, 66Zn and 68Zn, have no apparent interferences, but 32S1602 and 32S2 are isobaric with 64Zn. The possible effects of S and other major components of blood plasma-Na, K, Cl, P, Ca-on Zn IRs were investigated using a series of mineral solutions which simulated human plasma with respect to these elements. The mixture of all mineral elements interfered only with 64Zn (6.66 ng/mL) and 70Zn (8.51 ng/mL). Interferences to 66Zn, 67Zn, and 68Zn were minimal containing 0.90, 0.94, and 0.39 ng/mL, respectively. The copresence of Na or S shifted 35Cl16O2 (atomic mass 67 coming from Cl solution) to 35Cl2 which reduced the contribution to 67Zn. The hypothesis that Zn IRs obtained from plasma at various intervals after the intravenous administration of enriched 67Zn to humans would reflect those obtained after extraction of Zn was therefore tested. To compare the two pretreatment methods, "extraction" versus "nonextraction," specimens were collected from 10 human subjects at intervals of 5 min to 24 h postinjection, and in 4 subjects from 5 min to 9 d postinjection. Two separate aliquots of plasma from each time-point were dried and digested with hydrogen peroxide, and the residue dissolved in nitric acid. One specimen was subjected to zinc extraction using ammonium diethyldithiocarbamate chelate followed by back extraction into nitric acid. The matching aliquot received no further pretreatment. The normalized IRs obtained from 67Zn/66Zn and 67Zn/68Zn in both the "extracted" and "nonextracted" samples agreed well (r2 = 0.976 and r2 = 0.985, respectively) compared to those from other ratios (r2 = 0.838 for 67Zn/64Zn and r2 = 0.747 for 67Zn/70Zn). Considering the minimum possibility of isobaric interferences in plasma samples, 67Zn/68Zn obtained from "nonextracted" samples is sufficient for routine Zn kinetic analysis by ICP-MS.

Lead screening among low-income children in Galveston, Texas.

The objective of this study was to report results of a lead-screening program for low-income children living in Galveston, Texas. We obtained blood lead by graphite furnace spectrophotometry on 1,571 children aged 6 months to 8 years. Nineteen percent of children had blood lead levels > or = 10 mcg/dL. Risk factors included African-American ethnicity, young age, and residence in old housing. Follow-up was accomplished in only 50% of children with low-level toxicity. Lead screening is an important public health measure in communities with old houses. For screening to be successful, caregivers need to devote additional effort to follow-up.

Association of inorganic pyrophosphatase activity with normal calcification of rat costal cartilage in vivo.

1. Dialysed extracts of rat costal cartilage were shown to possess an enzyme that hydrolyses inorganic pyrophosphate. 2. Inorganic pyrophosphatase activity assayed in the presence of 2mm substrate was maximal at pH6.8. 3. Mg(2+) was essential for activity, which was greatest with 10mm or higher concentrations of Mg(2+). 4. Extracts prepared from cartilage taken from suckling rats (<20g.) showed little or no hydrolytic activity, but as rat weight increased inorganic pyrophosphatase activity was detected, increased to a maximum in tissue from animals weighing about 40g., and then rapidly declined. 5. The increase in inorganic pyrophosphatase activity was associated with an increase in the uptake of (45)Ca by the cartilage in vivo. 6. Accumulation of calcium, inorganic phosphate and magnesium occurred when inorganic pyrophosphatase activity was at its maximum. 7. Alkaline phosphatase activity, measured in the same extracts used to determine pyrophosphatase activity, was highest in the tissues of the animals weighing <20g., and decreased as inorganic pyrophosphatase activity increased to its maximum. 8. There was no direct relationship between alkaline phosphatase activity and the onset of calcification.

A model for studying the initiation of normal calcification in vivo.

1. Rat costal cartilage was found to begin to calcify normally when the rats weigh 35-45g. 2. The cartilage is suggested as a model for the study in vivo of mechanisms concerned with normal calcification. 3. The model was tested by studying the incorporation of fluoride into the mineral deposited in the tissue. 4. The percentage of inorganic material in cartilage rose from approx. 3% of the dry weight in the uncalcified tissue to 62% in the tissue from rats weighing 300g. 5. Mineral deposited had a calcium/phosphorus molar ratio of 1.65. 6. After the oral administration of sodium fluoride to rats, fluoride was incorporated into cartilage mineral. 7. The concentration of fluoride in cartilage ash increased rapidly with calcification and the mineral became more highly fluoridated than the corresponding rib bone. 8. Fluoridated mineral showed a marked decrease in citrate concentration.