Nancy W. Alcock

Comparison of methods of evaluating nephrotoxicity of cis‐platinum

The urinary excretion of leucine aminopeptidase (LAP), N‐acetyl‐β‐glucosaminidase (NAG), and β2‐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 β2‐microglobutin 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 values for these indices 6 wk after a dose demonstrates the persistent renal injury by cis‐platinum.

Gallium increases bone calcium and crystallite perfection of hydroxyapatite

SummaryGallium, a group IIIa metal, is known to interact with hydroxyapatite as well as the cellular components of bone. In recent studies we have found gallium to be a potent inhibitor of bone resorption that is clinically effective in controlling cancer-related hypercalcemia as well as the accelerated bone resorption associated with bone metastases. To begin to elucidate galliums mechanism of action we have examined its effects on bone mineral properties. After short-term (14 days) administration to rats, gallium nitrate produced measurable changes in bone mineral properties. Using atomic absorption spectroscopy, low levels of gallium were noted to preferentially accumulate in regions of active bone formation, 0.54±.07 μg/mg bone in the metaphyses versus 0.21±.03 μg/mg bone in the diaphyses,P<0.001. The bones of treated animals had increased calcium content measured spectrophotometrically. Rats injected with radiolabeled calcium during gallium treatment had greater 45-calcium content compared to control animals. By wide-angle X-ray analyses, larger and/or more perfect hydroxyapatite was observed. The combined effects of gallium on bone cell function and bone mineral may explain its clinical efficacy in blocking accelerated bone resorption.

Pharmacokinetics of gallium nitrate in man

Gallium nitrate is a new antineoplastic agent that has shown activity in a number of in vitro tumor systems. During a Phase I clinical trial, the pharmacokinetics of two methods of administration of gallium nitrate were studied: a seven‐day continuous intravenous infusion, and a weekly rapid intravenous infusion. During the continuous infusion of 200 mg/M2 of gallium nitrate, plasma gallium concentrations of 0.9 ± 0.2 μg/ml in one paitent, and 1.9 ± 0.4 μg/ml in a second were noted. Urine excretion of gallium approximated the daily administered dose by day 2–3. Overall, 68–107% of the total administered dose was recovered in the urine. Following a rapid intravenous infusion, a biphasic curve was generated. The T 1/2 α ranged from 8.3–26 minutes; the T 1/2 β from 6.3–196 hours. From 69–91% of the administered dose was recovered in the urine. The effects of gallium nitrate on tissue localization and body retention of 67Ga are also presented.

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.

Effect of gallium on bone mineral properties

SummaryGallium nitrate is biologically active in blocking bone rsorptionin vitro as well asin vivo. Administration of gallium nitrate to growing rats results in a dose-dependent accumulation of low levels of gallium in bone that is associated with specific changes in the mineral properties of bone. To elucidate in greater detail the changes induced by gallium, the properties of whole and density-fractionated bone samples from control and galliumtreated rats were examined. These studies showed that short-term treatment with gallium nitrate caused an increase in bone calcium and phosphate content. Devitalized bone powder from the gallium-treated rats was less soluble in acetate buffer and less readily resorbed by monocytes. Density fractionation analyses demonstrated that the largest proportion (76% by weight) of powdered metaphyseal bone particles from rats had a density of <2.15 g/cc. Following short-term treatment (14 days) with gallium nitrate (45 mg/kg body weight), a significant increase in the relative proportion of more dense bone (≥2.15 g/cc) was observed (24% for the control vs. 39% for the gallium-treated rats,P<0.01). In the diaphyseal samples, the largest proportion (88% by weight) of the bone powder had a density of ≥2.15 g/cc. After short-term treatment with gallium, a slight decrease in mean diaphyseal particle density was observed. Measurement of calcium accretion with45Ca in the gallium-treated rats demonstrated increased specific activity in the metaphyseal bone samples, densities=2.0, 2.1, 2.15, and 2.25 g/cc; the difference was significant only for the 2.25 g/cc fraction. Therefore, short-term treatment with gallium nitrate leads to an increase in the calcium content of mature bone with more dense (more mineralized) bone particles accumulating in the metabolically more active metaphyseal bone. The data provide greater insight into the changes in bone properties induced afterin vivo treatment with gallium nitrate. However, the physiologic mechanisms by which these changes are effected are not known.

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.

Gallium Nitrate for Treatment of Refractory Hypercalcemia from Parathyroid Carcinoma

Intractable hypercalcemia is the major cause of morbidity and mortality in patients with parathyroid carcinoma. Because gallium nitrate previously was shown to inhibit the bone resorptive activity of parathyroid hormone (PTH) in vitro, we used it to treat two patients with parathyroid carcinoma and resistant hypercalcemia. In both patients, total serum calcium levels were reduced from initial values of 3.62 and 3.77 mmol/L to posttreatment values of 2.32 and 1.45 mmol/L, respectively. Urinary excretion of calcium and hydroxyproline also declined significantly. Serum PTH levels were lower in both patients after therapy, although all levels remained markedly elevated. Nephrogenous cyclic adenosine monophosphate and tubular reabsorption of phosphate remained unchanged. These data indicate that treatment with gallium nitrate can control hypercalcemia in patients with high circulating levels of PTH. Gallium nitrate antagonizes the bone resorptive activity of PTH without altering renal effects of the hormone.

Cisplatin nephrotoxicity: correlation with plasma platinum concentrations

Plasma platinum concentrations were measured in 45 patients receiving 46 courses of cisplatin (DDP) 100-120 mg/m2 and in 21 patients receiving 35-60 mg/m2. Samples were drawn 5 minutes, 24, and 48 hours following completion of the DDP infusion. Nephrotoxicity was defined as a greater than 50% increase in serum creatinine measured at 24 and/or 48 hours when compared to the baseline pretreatment value. In patients receiving DDP 100-120 mg/m2, 5/20 with 5-minute plasma platinum concentrations greater than 6 micrograms/ml developed nephrotoxicity; 0/26 with concentrations less than 6 micrograms/ml became nephrotoxic (p less than 0.05). Concentrations at 24 and 48 hours in toxic and nontoxic patients were similar. Five-minute plasma platinum concentrations in excess of 6 micrograms/ml did not occur in the 21 patients receiving DDP 35-60 mg/m2. Only one of these 21 patients became nephrotoxic. The data suggest that an increased incidence of acute nephrotoxicity is related to high peak plasma platinum concentrations.

Pharmacokinetics of cisplatin regional hepatic infusions

Cisplatin (DDP), a potent antineoplastic agent, is usually administered via a peripheral vein. Recently, there has been considerable interest in intraarterial regional infusions of DDP. The pharmacokinetics of DDP when administered by this technique have not been explored in detail. We studied DDP pharmacokinetics in dogs given DDP by infusion and bolus injection in the hepatic artery (H.A.), portal vein (portal V), and peripheral vein (P.V.). Blood and biliary platinum concentrations ([Pt]) were assayed by flameless atomic absorption spectrophotometry. During an infusion into the H.S., peak [Pt] in the vessel were markedly higher (mean value 19 micrograms/ml) than those found, simultaneously, in the portal V or superior vena cava. Following a bolus injection of DDP into the H.A., higher H.A. [Pt] were also seen, but [Pt] rapidly (within 5-10 minutes) equilibrated in all sites sampled. During the H.A. infusion, most [Pt] was in its free (active) form. Bile and hepatic tissue were also sampled. Hepatic artery infusions of DDP give high drug concentrations in the perfusing blood, while systemic [Pt] are much lower. During the infusion, the majority of DDP is in its active (unbound) state.

Tissue concentrations and proliferative effects of massive doses of ascorbic acid in the mouse

The effect of ascorbic acid supplementation on CF1 mice fed ascorbic acid for approximately six months at dose levels of 1%, 5%, and 10% of diet was investigated by analysis of tissue ascorbic acid concentration in the liver, kidney, stomach, small intestine, and large bowel. The effect on epithelial cell proliferation was also examined in the small and large bowel but only at the 5% level. In the control animals, ascorbic acid concentration was lowest in the liver (0.406 +/- 0.07 mg/g) and highest in the small bowel (0.754 +/- 0.16 mg/g). Dietary intake of 5% and 10% ascorbic acid significantly elevated levels in the liver (0.741 +/- 0.13; p less than 0.05), and all doses of ascorbic acid significantly raised tissue concentrations in the kidney and colon. No difference was observed in the percentage of DNA-synthesizing cells in the jejunum of controls or animals fed 5% ascorbic acid at 1 or 24 hours after 3HTdR injection. However, at 1 hour a significantly decreased level of proliferation was observed in the distal colon of ascorbic-acid-treated mice compared with controls (labeling index [L.I.] = 7.3 +/- 0.28 vs. 10.1 +/- 1.15; p less than 0.05), and an even greater suppression of DNA synthesis was achieved by 24 hours (L.I. = 11.4 +/- 1.06 vs. 18.6 +/- 1.61; p less than 0.01). None of the doses of ascorbic acid employed was toxic to the experimental mice.