Quinocarmycin monocitrate is a novel antitumor antibiotic isolated from Streptomyces melanovinaceus. We have utilized a human tumor clonogenic assay to test the antitumor activity of this drug against carcinoma of the lung and to compare its activity with those of mitomycin C or cisplatin, which are components of the clinically effective regimens in therapy for this desease. The overall in vitro response rate (defined as less than 50% survival of tumor colony forming units) for quinocarmycin at 0.1 and 1.0 μg/ml continuous exposure was 42% and 72%, respectively, which was superior to that of other drugs. Quinocarmycin and other antitumor drugs do not have identical spectra of antitumor activities in vitro, suggesting that this compound with good in vitro activity should be further developed for clinical trials.

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The time courses of drug concentration in serum after i. v. drip infusion of 2 mg/kg of tobramycin and 25 mg/kg of cefazolin in children were analyzed by model-independent moment analysis. The volume of distribution at the steady state per body weight (V_dss/BW) of tobramycin was in the range of 212 to 335 ml/kg and that of cefazolin was 119 to 156 ml/kg. A plot of the differences of V_dss/BW obtained in the same child for tobramycin and cefazolin against the value of V_dss/BW of tobramycin gave a linear regression line (r=0.971). The magnitude of V_dss (1) of tobramycin could be well interpreted as corresponding to the extracellular water volume. In the case of cefazolin, the extracellular water space accounts for about 60% of the total distribution volume. The remaining 40% of the total V_dss of cefazolin was considered to be accounted for by the disposing organs.

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Crystalline lens of rainbow trout can be incubated in H₁₀ medium at 0°C for 2.5 months without loss of transparency and change in cation level. Applicability of this lens incubation system to test for drug toxicity was investigated. Changes in cation and glutathione (GSH) levels and lactic acid production which occurred with opacification were examined when the lens was treated with diamide, p-chloromercuribenzoic acid (PCMB), N-ethylmaleimide (NEM), 1, 2-naphthoquinone, ouabain and valinomycin. Among biochemical parameters, the increase in Na⁺-K⁺ ratio (Na⁺/K⁺) was most closely related to lens opacification, as in mammalian lenses. Lens opacification was observed macroscopically. Therefore, Na⁺/K⁺ was used as a lens toxicity parameter of the drug. Valinomycin was found to be the most effective drug as measured by the lowest concentration (1.0×10^-10 M) which gave an increase in Na⁺/K⁺. On the other hand, the lens treated with 2.5×10^-5 M NEM demonstrated neither change in Na⁺/K⁺ nor loss of transparency for 2.5 months. Lens toxicities due to diamide, PCMB, valinomycin and ouabain were detectable in the rainbow trout lens at 1000 times lower concentrations than those in the mouse lens. By using rainbow trout lenses incubated at 0°C, drug toxicity can be characterized by well-defined biochemical parameters and can be observed at lower concentrations for long periods of time. The rainbow trout lens is, therefore, very useful for studying long-term drug toxicity and the lens opacification mechanism.

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To assess the influence of different schedules of drug exposure in human tumor clonogenic assay on in vitro cytotoxicity of antitumor drugs, the in vitro sensitivities of a human carcinoma cell line, PC-9, to various antitumor drugs were measured by using two different procedures : exposure was either by pulse for 1 h prior to plating or continuous throughout the period of growth in agar. Marked differences between the two procedures in testing actinomycin D, etoposide, 5-fluorouracil, vinblastine and vindesine but not in adriamycin, daunomycin, melphalan, nimustine and ranomustine were observed. The former and the latter were classified as schedule dependent drugs and a schedule independent drugs, respectively. In this study, the schedule dependency of in vitro drug response appears to be related mainly to time-dependency and partially to other factors, such as stability during culture in medium.

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The variation in D-glucose uptake along the intestinal tract was examined by dividing the entire rat small intestine into 10 segments of equal length and by using everted sacs. The superiority of jejunurm to ileum in D-glucose uptake, which is generally accepted, was supported by this work. It was attributed mainly to the variation in the maximal transport velocity of the Michaelis-Menten type carrier-mediated transport system with a clear kinetic border in the distal location of the small intestine, between segments 7 and 8. Information obtained in this study is useful for understanding and estimating the absorption process, or the time-course of absorption, of D-glucose as it passes down in the intestinal tract.

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The radioactivity distribution of ⁷⁵Se-labeled D-selenomethionine (D-SeMet-⁷⁵Se) was investigated in tumor-bearing mice in order to develop a new radioactive diagnostic agent. D-SeMet-⁷⁵Se was enzymatically prepared from commercially available L-selenomethionine-⁷⁵Se (L-SeMet-⁷⁵Se) by using amino acid reacemase and immobilized L-amino acid oxidase. No difference between D- and L-SeMet-⁷⁵Se was found in the excretion rate into urine and feces in normal mice within 48 h after administration. The in vivo uptake of D-SeMet-⁷⁵Se in both Ehrlich solid tumor and sarcoma- 180 solid tumor was several times higher than that of L-SeMet-⁷⁵Se but the uptake of D- and L-SeMet- ⁷⁵Se were similar in the pancreas. These results indicated that D-SeMet-⁷⁵Se might be useful as a tumor-imaging agent. In vitro experiments on Ehrlich ascites tumor cells showed that D-SeMet-⁷⁵Se was incorporated into the tumor cells by a Na⁺-dependent active transport system similar to L-SeMet-⁷⁵Se and that a transport mechanism specific for D-SeMet-⁷⁵Se might be present in tumor cells in addition to a transport system common to both D- and L-forms.

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The pharmacokinetics and bioavailability of intravenous, intraduodenal, buccal, rectal and percutaneous nifedipine were studied in rats to evaluate the influence of route of administration. Plasma concentrations of nifedipine were determined by electron capture gas-liquid chromatography with preliminary oxidation of the drug to its pyridine analog. Pharmacokinetic evaluations were carried out by noncompartmental analysis of plasma concentration-time curves based on the statistical moment theory. The moments were computed by fitting a polyexponential function to the discrete time-course data of plasma concentration using the iterative least-squares method. A good computer fit to biexponential kinetics and a short mean residence time were observed after intravenous administration (i. v.). The linear distribution and disposition of nifedipine was found within the dosing range tested (0.025-0.100 mg/kg, i. v.). The systemic availability of nifedipine after intraduodenal administration was on the average between 52% and 57%, indicating that nifedipine is extensively metabolized during first passage through the liver. Avoidance of first-pass metabolism was investigated following buccal, rectal and percutaneous administration to rats. These nonportal routes of administration gave approximately 10-30% increases in systemic availability compared to that from intraduodenal nifedipine delivery. Moment analysis revealed variations of mixing condition of nifedipine at the dosing site. It was shown that the absorption occurs in a mammillary manner after intraduodenal and rectal administration. On the other hand, there is steady-state absorption of the drug from the buccal route of administration. Following percutaneous administration, the drug seems to be absorbed catenary to some degree. The amount of intact drug absorbed-time curve following noninstantaneous administration was simulated by a deconvolution method. Percutaneous nifedipine, as well as buccal nifedipine, appears to be a promising administration route from the viewpoint of sustained and controlled drug absorption.

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Age-dependent changes in phenytoin tissue bindings in rats were investigated by equilibrium dialysis using serum and 10% tissue (brain, lung, liver, kidney and muscle) homogenates. All percentages of phenytoin bound to serum and tissue homogenates were independent of the initial phenytoin concentration (2 to 25 μg/ml) in 1-d, 1-, 3- and 8-week-old rats. The percentages bound to serum, brain, liver, kidney and muscle in newborn rats (1-d-old rats) were lower than those in 8-week-old rats and the percentages bound increased gradually in the growth process. However, those in lungs were constant in all ages of rats. It was assumed that the age-dependent changes in phenytoin tissue binding were caused by the changes in the quantities of tissue constituents to which phenytoin bound in the growth process. Tissue-to-blood partition coefficients (K_p values) were calculated from in vitro tissue binding data and the pH-difference across the cell membrane. These K_p values were in good agreement with the in vivo K_p values reported previously. It was concluded that the age-dependent changes in phenytoin tissue distribution were caused by the age-dependent changes in phenytoin binding to blood constituents and tissues but that the change of phenytoin blood binding contributed to the age-dependent changes in K_p values of phenytoin more than to phenytoin tissue binding and consequently the K_p values of phenytoin decreased as rats grew.

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The antitumor activity of a highly branched (1→3)-β-D-glucan, SSG, purified from the liquid culture filtrate of Sclerotinia sclerotiorum IFO 9395 and its several derivatives were treated in ICR mice bearing Sarcoma 180 cells. SSG was effective by both systemic (intraperitoneal and intravenous) and local (intratumoral) administrations on the solid form of Satcoma 180 in ICR mice and the mice acquired resistance to subsequent inoculation of Sarcoma 180. However, SSG was not effective on the ascites form Sarcoma 180. The pretreatment of ICR mice with carrageenan suppressed the antitumor activity, suggesting the involvement of macrophages on the antitumor activity. Derivatives prepared from SSG by periodate oxidation/borohydride reduction showed antitumor activity, but those obtained after acetylation, carboxymethylation and hydroxyethylation were less active. From these results, it is suggested that SSG is a useful antitumor glucan which modifies biological responses and can be used as a source for some antitumor derivatives.

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A biological assay system has been developed for the simultaneous measurement of bone resorption and bone mineralization. In this system we (1) used chick embryonic femur as the biological material because of the easy handling and easy specification of developmental stages compared with rat and mouse, (2) labeled bone with ⁴⁵Ca in vitro, (3) calculated the biological half life (T_1/2) of ⁴⁵Ca incorporated into bone salts for quantitative estimation of the bone resorbing activity, and (4) investigated bone-mineralizing activity by determining the calcium content before and after cultivation. Eleven-day-old chick embryonic femur was labeled with ⁴⁵Ca in a chemically defined medium in vitro and thereafter labeled bones were transferred to chase medium. T_1/2 was calculated from the sequential release of the label into the medium from the cultured bone. No one heretofore had determined the T_1/2 of Ca in bone salts. We first determined in this study that the T_1/2 of Ca in the chick embryonic femur is about 50 h. The decrease in T_1/2 by parathyroid hormone, prostaglandin E₁ and E₂ and lipopolysaccharide, well-known stimulators of bone resorption, showed that this system works well in terms of bone resorption. By using this system, we demonstrated that immunomodulators such as Bacillus Calmette Guerin and Corynebacterium paruvum stimulate bone resorption and therefore affect bone metabolism. On the contrary, sodium fluoride (NaF) and hydrocortisone increased T_1/2, indicating that they inhibit bone resorption. These agents were also tested to determine if they would alter total calcium in the bone during cultivation. Those which resulted in the shortening of T_1/2 decreased total calcium during the cultivation period, probably because they stimulated bone resorption. On the contrary, NaF increased calcium content during cultivation. Fluorine ion, therefore, keeps bone hard not only by its direct incorporation into bone salts but also by aiding the accumulation of calcium into bone salts by inhibiting bone resorption. 1α, 25-dihydroxyvitamin D₃ and calcitonin, known as a stimulator and an inhibitor of bone resorption, respectively, had no effect on the T_1/2 in this system, indicating that some of the agents which affect bone resorption are not evaluated in this system. Our system, however, offers a simple and quantitative method for simultaneous measurement of bone resorption and bone mineralization. Therefore, we can use this system as the initial assay system for the identification of new drugs for the treatment of bone disease, even though there are some limitations in this system.

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Modes of action of befunolol and its derivatives were tested in guinea pig isolated taenia caecum. The pA₂-values of BFE-60 (befunolol), -61 and -69 against isoprenaline, which measures interactions with the high affinity sites on beta-adrenoceptors, were significantly larger than their pD₂-values, which were equal to their pA₂-values against carteolol. Carteolol is a beta-adrenergic partial agonist with higher intrinsic activity, to which the response results from interaction with low affinity sites. These results suggest that BFE-60, -61 and -69 discriminate the high and low affinity sites on beta-adrenoceptors. The pA₂-values of BFE-37, -41, -47 and -72 against isoprenaline were, however, equal to their pD₂-values and pA₂-values against carteolol. These drugs seem to have little or no ability to discriminate between the high and low affinity sites. BFE-55 antagonized isoprenaline but not carteolol suggesting that BFE-55 interacted with only the high affinity sites.

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Serum dimethadione (DMO)/trimethadione (TMO) ratios after oral administration of TMO have been investigated in 10 patients with normal livers, 8 patients with hepatoma and 8 patients with hepatoma and cirrhosis. Serum concentration ratios of DMO to TMO at 4 h after oral administration of TMO in patients with chronic liver disease were significantly decreased by 27% for those with hepatoma and 52% for those with hepatoma and cirrhosis. Serum DMO/TMO ratios at 4 h correlated well with liver function characteristics (total protein r=0.741, plasma albumin r=0.826, total bilirubin r=-0.725, cholinesterase r=0.853) as well as with pharmacokinetic parameters (total body clearance r=0.852, half-life r=-0.636) in both patients with normal livers and patients with chronic liver disease. This study suggests that serum DMO/TMO ratios in a blood sample obtained by a single collection after an oral administration of TMO might provide a clinically useful index of the hepatic drug-oxidizing capacity in an individual patient with chronic liver disease without determining the liver function characteristics or the pharmacokinetic parameters.

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Development of cross reverse tolerance between D-amphetamine, cocaine and morphine to their ambulation accelerating- and swimming time prolonging-effects was investigated in mice. D-Amphetamine and cocaine pretreatment did not increase the ambulation or swimming time by morphine, and pretreatment with morphine produced an increase in the response to D-amphetamine and cocaine. Thus, the difference of the underlying mechanisms between morphine and other drugs for the development of reverse tolerance to their ambulation accelerating and swimming time prolonging effects was demonstrated.

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