Binding kinetics of tetrachloro-1,2-diaminocyclohexaneplatinum (IV) (tetraplatin) and cis-diamminedichloroplatinum (II) at 37 degrees C with human plasma proteins and with bovine serum albumin. Does aquation precede protein binding?

Experiments were conducted at 37 degrees C to study the kinetics of (a) binding of cis-diamminedichloroplatinum (II) (CDDP) and of a racemic mixture of d- and l-isomers of trans-tetrachloro-1,2-diaminocyclohexaneplatinum (IV) [or tetraplatin (TP)] to protein [human plasma proteins or bovine serum albumin (BSA)]; (b) aquation (acid hydrolysis) of CDDP and of TP; and (c) binding of charged (aquated) CDDP species to BSA. The experiments were performed at clinically relevant concentrations for CDDP, so that the proportional concentrations of platinum complexes relative to the concentrations of other chemical species in blood plasma were similar to those obtaining in the clinical use of the drug. "Free" (unbound) platinum complexes were separated from the protein-bound complexes were separated from the protein-bound complexes by gel filtration chromatography. By use of ion-exchange chromatography, charged platinum species were separated from the uncharged species and free charged platinum species of CDDP were separated from those bound to BSA. Platinum in various fractions was quantitated by atomic absorption spectrophotometry with electrothermal atomization; proteins were quantitated by te Bradford method with Coomassie blue dye. The kinetic data obtained by the application of these methods for CDDP are in good agreement with those obtained by other methods, e.g., binding rates based on separations by centrigugal ultrafiltration. The overall protein-binding reaction of CDDP was consistent with a binding process comprising two consecutive first-order reaction steps: the rate-controlling aquation reaction [half-life (t 1/2), approximately 2 hr] followed by a more rapid binding reaction of the charged (aquated) CDDP species to the protein (t 1/2, approximately 23 min). However, the results for TP indicated that prior aquation was not required for protein binding, and we could surmise that binding of TP to protein proceeds via a direct nucleophilic attack. An unexpected finding was the marked, reproducible difference in rates of aquation between the two lots of TP that we used; this finding suggests the need for cautions evaluation of pharmacokinetic data describing the behavior of TP.

Determination of platinum-containing drugs in human plasma by liquid chromatography with reductive electrochemical detection.

The platinum complex cis-diamminedichloroplatinum(II)(cisplatin or CDDP), which is used successfully to treat various kinds of tumour, can be determined in human plasma ultrafiltrate using liquid chromatography with reductive electrochemical detection (LC-ED). Polarographic analyses of other platinum-containing drugs have been carried out, and the results indicate that some of them might be good candidates for detection using the ED method. cis-Dichloro-trans-dihydroxo-cis-bis-(isopropylamine)platinum(IV) (CHIP or JM-9), diammine(1,1-cyclobutanedicarboxylato)platinum(II) (CBDCA or JM-8), and tetrachloro(trans-1,2-diaminocyclohexane)platinum(IV) (TCDCP), which are under evaluation for antitumour properties, have been investigated by this method. The results suggest that LC-ED may be a suitable technique for the determination of CHIP and TCDCP. The separation of cationic hydrolysis products from the neutral parent complex (CDDP) was carried out on reversed-phase columns, modified with alkylsulphonic acid ion-pair reagents. The rate of disappearance of CDDP in various media at 37.0 degrees C was studied using this method. These results are in good agreement with those determined by other investigators using different methods. In addition, the monoaqua hydrolysis product was detected after incubation of CDDP with plasma ultrafiltrate and 100 mM sodium chloride. Atomic absorption spectrophotometry with electrothermal atomisation was used to determine the total platinum content in eluate fractions. This aided the identification of platinum-containing peaks in the LC-ED profile, and was also used to measure the percentage platinum recovered from the column.

Determination of cis-diamminedichloroplatinum(II) in human plasma using ion-pair chromatography with electrochemical detection.

A thin-layer gold/mercury electrode and a hanging mercury drop electrode are compared as part of an evaluation of liquid chromatography (LC) with electrochemical detection (ED) for the determination of platinum species in human plasma ultrafiltrate. The platinum species, derived from an aged aqueous solution of the antineoplastic agent cis-diamminedichloroplatinum(II) (CDDP), can be separated by ion-pair chromatography. Variation of a number of parameters is described along with the limitations and advantages of each kind of electrode system. We have used our LC-ED technique to separate CDDP from its hydrolysis products and other non-platinum-containing species in human plasma ultrafiltrate with a detection limit of 62 ng/ml (ppb).

Disposition and distribution of platinum following parenteral administration of cis-dichlorodiammineplatinum(II) to animals.

After iv administration of cis-dichlorodiammineplatinum(II) (cis-platinum) to animals, plasma levels of platinum decline in a biphasic manner, with a distribution phase (alpha) half-life of minutes and an elimination phase (beta) half-life of days. Urinary excretion of platinum is extensive on the first day after drug administration with a final urinary recovery of 70%--90% of the administered dose. Platinum is initially distributed to nearly all tissues with the highest levels appearing in kidney, liver, ovary, uterus, skin, and bone. There is no preferential uptake of platinum into tumor, although the presence of a tumor may alter the rate of platinum excretion and the extent of whole-body retention. No effect is seen on hepatic microsomal drug metabolism after ip administration of cis-platinum to rats. Platinum is excreted more rapidly from hydrated animals than from controls although total urinary recovery of platinum is nearly equal in both groups. Most analogs of cis-platinum appear to follow the same elimination and distribution patterns as cis-platinum itself.

Kinetics of cis-dichlorodiammineplatinum.

The cancer chemotherapeutic cis-dichlorodiammineplatinum (cis-DDP) was administered to 8 patients (1-hr intravenous infusion) at a dose of 70 mg/m2. Plasma and urine concentrations of platinum were determined by flameless atomic absorption spectrometry. Measured plasma platinum concentrations revealed a biphasic clearance of platinum with half-life values of 23 min and 67 hr. Platinum values obtained 3 wk after the infusion indicated that a third excretory phase might be present. Urinary measurements showed 17 +/- 2.7% of the administered dose excreted in the first 4 hr and 23 +/- 3.9% excreted in the first 24 hr. Renal excretion appears to be predominantly by glomerular filtration. Non-protein-bound plasma platinum values were calculated and the non-protein-bound platinum was found to be rapidly and biphasically cleared from the plasma with half-life values of 8 to 10 min and 40 to 45 min.

The pulsed Doppler ultrasound flowmeter: experimental evaluation of velocity accuracy and range resolution.

Accurate quantitation of blood flow patterns, particularly in the physiological state, is important to the successful study of several problems in biomedical research. The pulsed Doppler ultrasonic flowmeter offers promise of overcoming some of the difficulties present in other methods. This flowmeter can be either implantable or noninvasive. Although a number of papers describe important design criteria, the design or selection of a Doppler system for a given task remains a complex matter involving many compromises based on theoretical considerations and very limited data. Experimental data from well-defined flows are needed to help identify those areas in which ultrasonic flowmeters can be most useful. This paper defines and evaluates two important parameters for the pulsed Doppler ultrasonic flowmeter by comparing experimental results with those predicted theorectically. The first parameter is velocity accuracy; the second parameter is range resolution. Findings show that centerline flow velocities in circular tubes can be estimated to within a few percent of the correct value, and that a 1.5-mm range resolution can be realized with the system tested.

Distribution and disposition of platinum following intravenous administration of cis-diamminedichloroplatinum(II) (NSC 119875) to dogs.

cis-Diamminedichloroplatinum(II) is an antineoplastic drug that is undergoing a renewed clinical interest as a drug for use in combination regimens. In order to increase the understanding of the pharmacokinetics of this drug, the plasma clearance and organ distribution of platinum were followed in female beagle dogs treated with a single i.v. dose of cis-diamminedichloroplatinum(II). Plasma levels of platinum were determined by flameless atomic absorption spectrometry and showed a distinctly biphasic clearance pattern with a rapid-phase half-time of considerably less than 1 hr and a slow-phase half-time of nearly 5 days. During the first 4 hr after treatment, plasma levels fell by 90% while 60 to 70% of the applied dose was recovered in the urine. Sixteen tissues plus plasma, bile, and urine were routinely analyzed for platinum content. An easily measurable plasma concentration of platinum was still detectable 12 days after treatment, with no significant change in plasma concentration between Days 4 and 12. Initial concentrations of platinum were highest in organs of excretion, gonads, spleen, and adrenals but remained significantly elevated only in kidney, liver, ovary, and uterus, where a tissue: plasma ratio of 3 to 4 was maintained for as long as 6 days posttreatment. The apparent in vitro binding of platinum to dog plasma and to bovine serum albumin was studied by ultrafiltration and increased progressively during 48 hr of incubation at 37 degrees.

Surface and bulk characteristics of a polyether urethane for artificial hearts.

A segmented polyether urethane was used as the blood contacting surface in a series of 10 heart assist devices implanted in calves for periods up to 35 weeks. At termination, each was examined to correlate blood compatibility and device performance with surface properties, chemical purity, physical stability and affinity for lipid absorption.

Interactions of platinum metals and their complexes in biological systems.

Platinum-metal oxidation catalysts are to be introduced in exhaust systems of many 1975 model-year automobiles in the U.S. to meet Clean Air Act standards. Small quantities of finely divided catalyst have been found issuing from prototype systems; platinum and palladium compounds may be found also. Although platinum exhibits a remarkable resistance to oxidation and chemical attack, it reacts chemically under some conditions producing coordination complex compounds. Palladium reacts more readily than platinum. Some platinum-metal complexes interact with biological systems as bacteriostatic, bacteriocidal, viricidal, and immunosuppressive agents. Workers chronically exposed to platinum complexes often develop asthma-like respiratory distress and skin reactions called platinosis. Platinum complexes used alone and in combination therapy with other drugs have recently emerged as effective agents in cancer chemotherapy. Understanding toxic and favorable interactions of metal species with living organisms requires basic information on quantities and chemical characteristics of complexes at trace concentrations in biological materials. Some basic chemical kinetic and thermodynamic data are presented to characterize the chemical behavior of the complex cis-[Pt(NH3)2Cl2] used therapeutically. A brief discussion of platinum at manogram levels in biological tissue is discussed.

Electrolyte and morphologic alterations of myocardium in adriamycin-treated rabbits.

Rabbits receiving adriamycin (ADR) on a chronic schedule developed significant histopathologic, ultrastructural and tissue electrolyte alterations of the ventricular myocardium. Rabbits that developed clinicopathologic evidence of cardiomyopathy with ADR had histologic lesions of the myocardium, including perivascular fibrosis, interstitial fibrosis and edema and myocytolysis. Ultrastructurally, large vacuoles resembling distended sarcoplasmic reticulum displaced the contractile elements and mitochondria, which were diminished in number within affected myocytes. Frequently, mitochondria appeared as electron-dense structures surrounded by layers of membranes resembling myelin figures. In addition, rabbits with cardiomyopathy had marked elevations in ventricular Ca, Na and H(2)O concentrations. Serum electrolytes were not significantly elevated, but lactic dehydrogenase (LDH) and creatine phosphokinase (CPK) were significantly increased, indicative of a cardiomyopathy. Rabbits receiving ADR but not developing clinicopathologic evidence of heart failure also had significant elevations in ventricular Ca, Na and H(2)O. Rabbits with no cardiomyopathy had no increases either in serum electrolyte concentrations or CPK and LDH levels. These studies indicate that marked increases in ventricular tissue Ca precede and accompany morphologic evidence of chronic myocardial degeneration and may be instrumental in the development of the ADR-induced cardiomyopathy.

Use of a fiber optic probe for spectral measurements and the continuous recording of the turbidity of growing microbial cultures.

This paper describes the properties and use of a fiber optic probe as an attachment to a spectrophotometer and its use for measurements in solutions and turbid suspensions. Measurements of a standard were identical when a spectrophotometer equipped with the probe was used or when a spectrophotometer was used in a conventional manner. The probe was calibrated for turbidimetric measurements with microorganisms by relating the apparent absorbancy measured on the spectrophotometer to the dry weight of each species of organism. Continuous measurements were made of the turbidity of growing cultures of Escherichia coli, Streptococcus mutans, and Saccharomyces cerevisiae. Transient changes in cell mass were observed in some cultures during continuous monitoring of growth. The data were recovered in a manner which allowed direct computer processing.