Induction of single-strand regions in nuclear DNA by adriamycin.

Incubation of adriamycin with isolated nuclei converts nuclear DNA to a form which is susceptible to hydrolysis by $\text{Neurospora}$$\text{crassa}$ nuclease an enzyme highly specific for the cleavage of single-stranded DNA. The effect of adriamycin on nuclear DNA incubated in the presence of the nuclease can be determined by measuring the release of acid-soluble nucleotides or by analyzing the DNA after centrifugation in neutral sucrose gradients. Similar changes in chromatin structure are not observed during incubation of nuclei with adriamycin alone. In addition to adriamycin, daunomycin and ethidium bromide are also active in inducing the formation of DNA structures which are susceptible to the $\text{Neurospora}$$\text{crassa}$ nuclease. The results suggest that certain antitumor agents can induce the formation of single-strand regions in nuclear DNA and that these sites probably occur as a result of a DNA strand separating event.     

Protection by N-acetylcysteine of cyclophosphamide metabolism - related invivo depression of mixed function oxygenase activity and invitro denaturation of cytochrome P-450

Cyclophosphamide (CP) at high or repeated doses results in the depression of mixed function oxygenase activities of the liver. Recent studies have attributed this to the interaction between acrolein, a metabolite of CP, and sulfhydryl groups in cytochrome P-450. The present report demonstrates the protection afforded by N-acetylcysteine against acrolein-induced denaturation of cytochrome P-450 $\text{in}\text{vitro}$ and CP-related depression of mixed function oxygenase $\text{in}\text{vivo}$. Co-administration of CP and innocuous chemicals that provide free sulfhydryl groups should, in the future, be useful in enhancing the therapeutic index of CP by either reducing some of the toxicity and/or by allowing the use of repeated treatment with lower but effective doses of CP.     

Anti-inflammatory properties of cannabichromene

It was not known if Cannabichromene (CBC), which is a major constituent of drug types of $\text{Cannabis}$, has anti-inflammatory properties as do other cannabinoids. CBC was tested $\text{in vivo}$ using the rat paw edema test and $\text{in vitro}$ using the erythrocyte membrane stabilization assay. CBC was as effective as phenylbutazone (PBZ) at equivalent doses. Since CBC is less toxic than PBZ, larger doses may be given to produce a greater therapeutic effect.     

In vivo binding of spiroperidol and bromosphiroperidol at low drug loadings

The binding of spiroperidol and bromospiroperidol, $\text{in vivo}$, was studied over a wide range of drug dosages. It was found that while spiroperidol and bromospiroperidol bind selectively $\text{in vivo}$ to tissues known to be high in dopamine receptor binding sites, this specificity of binding does not persist at very low doses. Such anomalous binding behavior can have implications for the non-invasive imaging of these drugs.     

Trilostane,an orally active inhibitor of steroid biosynthesis

Trilostane is a competitive inhibitor of 3β-hydroxysteroid dehydrogenase. $\text{In}$$\text{vitro}$, the drug inhibits conversion of pregnenolone to progesterone but does not alter conversion of cholesterol to pregnenolone nor progesterone to corticoid hormones. When given orally to rats, trilostane inhibits corticosterone and aldosterone production and elevates circulating levels of pregnenolone at doses lower than those that produce adrenal hypertrophy or inhibit gonadal steroidogenesis.     

Acute inhibition of microsomal drug metabolism by propoxyphene in narcotic tolerant/dependent mice

Propoxyphene (Darvon) was compared to SKF 525-A, a prototypical inhibitor of hepatic microsomal mixed function oxidases, to assess propoxyphene's potential to inhibit drug metabolism in morphine tolerant/dependent mice. $\text{In vitro}$, both propoxyphene (K_i = 3.5 × 10^?5M) and SKF 525-A (K_i = 4.3 × 10^?6M) inhibited the activity of aminopyrine N-demethylase competitively in hepatic microsomes from tolerant/dependent animals. Propoxyphene and SKF 525-A were weaker, noncompetitive inhibitors of aniline hydroxylase activity. $\text{In vivo}$, equimolar doses (0.24 mmoles/kg, i.p.) of each compound inhibited both of the above monooxygenases in the 10,000$\text{g}$ supernatant fractions of livers from the tolerant/ dependent animals. Propoxyphene was 40–50% as potent an inhibitor of these activities as SKF 525-A. A dose (300 mg/kg) of propoxyphene napsylate, shown to prevent narcotic abstinence signs with no observable toxicity in withdrawing mice, significantly prolonged the blood levels of injected pentobarbital and tripled pentobarbital sleeping time in these animals. When administered at 300 mg/kg chronically, propoxyphene napsylate acted as an inducer of its own metabolism. Propoxyphene napsylate, then, given acutely to narcotic tolerant/dependent mice, is a potent inhibitor of microsomal drug metabolizing capacity. Given chronically, it enhances this capability.     

A new test of peripheral insulin sensitivity invivo using artificial beta cell

A new $\text{in}$$\text{vivo}$ test of insulin sensitivity is described. It utilizes closed-loop insulin delivery device (GCIIS, Biostator^®) capable of infusing glucose and insulin according to preselected algorithms. In euglycemic patients, insulin was infused by GCIIS to maintain euglycemia in the face of challenges with gradually increasing doses of intravenously administered glucose. Under the described experimental conditions, the endogenous insulin release was minimized as evidenced by serum C-peptide levels of less than 2 ng/ml, and thus the peripheral disposal of glucose should have depended entirely on the exogenous insulin. The amount of the insulin infused was considered to be a measure of peripheral insulin sensitivity. The test was applied to normal and non diabetic obese individuals, and to diabetics, both insulin dependent and independent. Significant insulin resistance was demonstrated in the obese and diabetic patients. In two obese females, the test was repeated after a prolonged period of starvation, and showed marked increase in insulin sensitivity. In two poorly controlled insulin dependent diabetics, marked increase in insulin sensitivity was also observed, here following a prolonged period of euglycemia (48 hours). It is concluded that the GCIIS controlled insulin sensitivity test is a simple, reliable test of peripheral insulin sensitivity, most convenient for clinical and experimental studies $\text{in}$$\text{vivo}$     

Effects of acute and chronic trazodone administration on serum prolactin levels in adult female rats

Trazodone was tested for its ability to elevate serum prolactin levels in mature female rats. When the drug was administered acutely to female rats at doses up to 80 mg/kg ip, it induced a clear rise in serum prolactin levels, with a minimum effective dose of 20 mg/kg; blood trazodone levels at these doses were between 1.6–2.4 μg/ml. However, trazodone could not be considered to be a potent stimulator of prolactin secretion, since the injection of haloperidol at 2 mg/kg elevated serum prolactin to values twice those seen in animals receiving the 80 mg/kg dose of trazodone. When trazodone was administered chronically in the diet for two or four weeks, at an average daily dose of 80 mg/kg, serum trazodone levels were found to be 100–200 ng/ml when measured at each stage of the estrous cycle. Serum prolactin levels in trazodone-treated animals, however, did $\text{not}$ differ from those in control rats. Moreover, drug-treated animals showed normal proestrus surges in serum prolactin. The results of these studies thus indicate that acutely, at very high doses, trazodone probably can stimulate prolactin secretion modestly in female rats. However, when consumed chronically at 80 mg/kg/day, the drug has no effects on serum prolactin levels. Therefore, if trazodone stimulates prolactin secretion by altering neurotransmission across dopamine and/or serotonin synapses in brain, it is probably not potent in these actions, at least as concerns those dopamine and serotonin neurons that influence the secretion of prolactin.     

An attempt to isolate Brucellaabortus from uterine flushings of brucellosis-reactor donor cattle

Two experiments were conducted to test for the recovery of brucella organisms from uterine flushings and harvested embryos of sero-positive embryo donor females. In Experiment I, 16 sero-positive cows were superovulated with FSH treatments and artificially inseminated at 12, 24 and 36 hours following the onset of estrus with brucella-free semen. At 48 hours after the onset of estrus, one half the potential donor females were administered an intrauterine inoculation of 3.3 to 4.6 × 10⁴$\text{Brucella}$$\text{abortus}$ (strain 2308) organisms while the remainder received a control inoculation. In Experiment II, the same 16 cows were similarly administered superovulatory treatments and inseminated following estrus. The uterine inoculation was increased to 1.5 to 2.5 × 10⁸ organisms administered 48 hours following estrus. Samples of recovered flushing medium and homogenized embryo residues were placed into a validated $\text{in}$$\text{vitro}$ culture system to detect the presence of brucella bacteria. Uterine flushings and embryos recovered from 31 females exhibiting estrus following FSH treatments were free from either field strain or the inoculated $\text{B.}$$\text{abortus}$ (strain 2308) contamination. The flushings obtained from a single female, which did not respond with estrus following FSH treatment but was inoculated at appointment, did contain $\text{B.}$$\text{abortus}$ which was identified as the inoculated strain 2308 and not field strain organisms. These results indicate that brucella contamination of flushing media and harvested embryos will not likely be incurred when collecting embryos from sero-positive donor females. These findings offer further encouragement for the use of embryo transplantation as a method to produce brucella-free offspring from infected cows.     

Metabolism of propranolol in rat: the fate of the N-isopropyl group

The metabolic fate of the side-chain of propranolol has been studied in the rat $\text{in vivo}$ and with liver preparations $\text{in vitro}$ using drug labelled with ¹⁴C in the isopropyl group. Oxidative N-dealkylation to yield acetone was the major route of metabolism $\text{in vitro}$. Direct deamination to form isopropylamine was a very minor pathway of metabolism of propranolol by rat liver. In the intact rat only 1.4% of an intra-peritoneal dose of propranolol was excreted as isopropylamine in urine. In addition, isopropylamine administered to a rat was rapidly excreted unchanged in urine. Thus, if a similar metabolic pattern obtains in man, it seems unlikely that part of the pharmacological effects of propranolol can be attributed to this active metabolite.     

Cardiovascular effects and pharmacokinetics of the carboxylic ionophore monensin in dogs and rabbits

Monensin, a carboxylic ionophore, produces strong pressor, positive chronotropic effects and elevates the blood glucose level when injected intravenously (100 μg/kg) into pentobarbital anesthetized dogs or administered orally (2 mg/kg) to conscious dogs. Intravenously administered monensin disappeared from the blood rapidly with a $\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ of ca. 2.5 min and, in the conscious dogs, ingested monensin showed a peak plasma level 90 min after feeding; this coincided with the time of maximum increase in arterial blood pressure and blood glucose. In conscious rabbits, although higher doses of monensin were administered, 200 μg/kg intravenously and 10 mg/kg orally, its cardiovascular effects were less than observed in the dog and were slower in onset. This correlated with slower clearing of injected monensin from the blood ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 8}\text{min}$) and slower entry of ingested monensin from the gut into the blood. Rabbit plasma and tissue levels were higher 17 hr after oral ingestion of monensin than six hr after ingestion.     

Potent hypotensive activity of 1-O-hexadecyl-2-O-acetyl-sn-glycero-3-phosphocholine in spontaneously hypertensive rat

Chemically synthesized 1-O-hexadecyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine possessed the most potent hypotensive activity compared with bradykinin, prostagrandin E₂ and I₂ when 5 nano moles/kg body weight of each drug were administered intravenously in spontaneously hypertensive rat. The potency and the duration of hypotensive activity of 1-O-hexadecyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine were dose dependent. Exogenous norepinephrine or angiotensin II showed pressor activity during the hypotensive action of 1-O-hexadecyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine, but did not disturb the hypotensive pattern of this ether lipid. These may suggest that 1-O-alkyl-2-O-acetyl-$\text{sn}$-glycero-3-phosphocholine plays an important role for the regulation of blood pressure.     

Preliminary study of caffeine and chloroquine enhancement of x-ray induced birth defects.

Caffeine and chloroquine were administered to pregnant $\text{SAF}\text{ICR}$ mice at doses which were non-teratogenic. Nevertheless, these dose levels enhanced significantly the number of cleft palates produced by 200 rads x-ray. The combination of chloroquine with 200 rads x-ray also resulted in a substantially higher incidence of tail abnormalities. Although the mechanisms of action for most teratogens are undefined, mutagenic damage to DNA has been implicated. We propose a “co-teratogenic” mechanism by which non-teratogenic agents enhance the effectiveness of gene damage in producing fetal abnormalties.     

Synthesis of carnitine from ε-N-trimethyllysine in post mitochondrial fractions of Neurospora crassa

An enzyme system in the post mitochondrial fraction of $\text{Neurospora}$$\text{crassa}$ when supplemented with appropriate cofactors formed carnitine from ε-N-trimethyllysine. These findings together with previous studies of ε-N-lysine methylation in this fungi, illustrate that carnitine synthesis in $\text{Neurospora}$ differs markedly in certain features from mammalian systems in that the entire synthesis is carried out employing free intermediates and cytosolic enzymes.     

Interaction of oncodazole (R 17934), a new antitumoral drug, with rat brain tubulin.

Oncodazole (R 17934), methyl [5-(2-thienylcarbonyl)-1H-benzimidazol-2-yl] carbamate (I), a new synthetic drug with anti-tumoral activity, inhibits the polymerization of rat brain tubulin $\text{in vitro}$. It has no depolymerizing effect on preformed microtubules $\text{in vitro}$. Binding studies by means of molecular sieving and equilibrium dialysis indicates that the drug binds to purified rat brain tubulin in a mole to mole ratio. Finally the drug competitively inhibits colchicine binding to purified rat brain tubulin. From these results the conclusion may be drawn that oncodazole is a true microtubule inhibitor.     

Differential effects of d-amphetamine, β-phenylethylamine,cocaine and methylphenidate on the rate of dopamine synthesis in terminals of nigrostriatal and mesolimbic neurons and on the efflux of dopamine metabolites into cerebroventricular perfusates of rats

The $\text{in}$$\text{vivo}$ of four psychomotor stimulants (d-amphetamine, β-phenylethylamine, cocaine and methylphenidate) were determined on: 1) the rate of dopamine (DA) synthesis, as measured by the accumulation of dihydroxyphenylalanine (DOPA) after aromatic L-amino acid decarboxylase inhibition, in the striatum (terminals of nigrostriatal neurons) and in the nucleus accumbens and olfactory tubercle (terminals of mesolimbic neurons) and 2) the efflux of the DA metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) into cerebroventricular perfusates of conscious, freely-moving rats. d-Amphetamine and β-phenylethylamine produced biphasic responses with lower doses of each drug increasing both the efflux of DOPAC and the rate of DA synthesis in the striatum. Higher doses of each drug either had no effect or actually decreased the efflux of DOPAC and also decreased the rate of DA synthesis in the striatum. Higher doses of each drug either had no effect only decreased the efflux of DOPAC and the rate of DA synthesis in the striatum. The effects of the drugs on the rate of DA synthesis in the nucleus accumbens and olfactory tubercle were similar to, but less pronounced than those seen in the striatum. These results are consistent with the following suggestions: 1) low doses of d-amphetamine and β-phenylethylamine facilitate the neuronal release of DA while higher doses of both drugs facilitate release and inhibit neuronal reuptake of the amine, and 2) cocaine and methylphenidate preferentially block the neuronal reuptake of DA.     

ICI 125,211: a new gastric antisecretory agent acting on histamine H2-receptors.

$\text{In}$$\text{vitro}$, ICI 125,211 competitively antagonized the action of dimaprit on guinea pig atrium with an apparent dissociation constant of 1.5 × 10^?8M (pA₂ = 7.8). $\text{In}$$\text{vivo}$, the histamine dose-response curve in conscious gastric fistula beagles was shifted rightward in parallel without change in the maximal response by intravenous infusions of ICI 125,211 at doses of 0.01 and 0.03 umol/kg/hr (estimated pA₂ = 7.3). Our data show that this new drug is at least 10x more potent than cimetidine as an inhibitor of gastric secretion in the dog. ICI 125,211, which is an orally effective antisecretory agent in man and devoid of antiandrogenic activity, is the most potent selective H₂-blocker described to date.     

Suppressive actions of inorganic ions on the bioactivity of aminoglycoside antibiotics.

Many independent studies have shown that inorganic salts can suppress the inhibitory activities of aminoglycoside antibiotics against various bacterial species. From studies on the nature and mechanism of this suppressive ion effect, several conclusions can be drawn. Both monovalent and divalent cation salts can inhibit aminoglycoside action. At least two different mechanisms are apparently involved. The first is divalent cation dependent and has been described with $\text{Pseudomonas aeruginosa}$ and $\text{Mycobacterium smegmatis}$. With $\text{M. smegmatis}$, the effect aappears to be dependent more on a double positive charge than on particular metal ion species. The second mechanism is related to ionic strength and is elicited by both monovalent and divalent cation salts against many different organisms. However, based on studies with $\text{M. smegmatis}$, it appears that each of the two mechanisms involves interferance with the initial instantaneous electrostatic binding of drug at the cell surface.     

The effects of quipazine on serotonin metabolism in rat brain.

Quipazine, 2-(1-piperazinyl)-quinoline, is a drug that has been reported to stimulate serotonin receptors in brain. We therefore studied the effect of quipazine on several parameters of serotonin metabolism in rat brain. Quipazine caused a slight, dose-related elevation of serotonin levels and decrease in 5-hydroxyindoleacetic acid levels for 2–4 hrs after it was administered. The decrease in 5-hydroxyindoleacetic acid levels was probably due primarily to a depression of 5-hydroxyindole synthesis, since quipazine also decreased the rate of 5-hydroxytryptophan accumulation after NSD 1015, the rate of serotonin decline after α-propyldopacetamide, and the rate of 5-hydroxyindoleacetic acid accumulation after probenecid. The elevation of serotonin was probably due to weak inhibition of monoamine oxidase. Quipazine reversibly inhibited the oxidation of serotonin by rat brain monoamine oxidase $\text{in}$$\text{vitro}$ and protected against the irreversible inactivation of the enzyme $\text{in}$$\text{vivo}$. Quipazine also was a potent inhibitor of serotonin uptake into brain synaptosomes $\text{in}$$\text{vitro}$ and attained concentrations in brain higher than the $\text{in}$$\text{vitro}$ IC₅₀. However, quipazine did not prevent the depletion of brain serotonin by p-chloroamphetamine $\text{in}$$\text{vivo}$. In addition to stimulating serotonin receptors in brain, quipazine may inhibit monoamine oxidase and serotonin reuptake $\text{in}$$\text{vivo}$.     

Displacement of palmitate from albumin by chlorophenoxyisobutyrate.

The effect of chlorophenoxyisobutyrate, a hypolipidemic drug that decreases plasma free fatty acids, triglycerides, and cholesterol, on the partitioning of [¹⁴C]-palmitate between hexane and bovine serum albumin was studied at 37°. In this system, hexane served as a hydrophobic trap for free fatty acids displaced from BSA by chlorophenoxyisobutyrate, allowing less than 0.3% to remain in the aqueous phase. As the concentration of chlorophenoxy isobutyrate was raised from 0.4 to 3.2 mM, there was a progressive displacement of palmitate from the [¹⁴C]-palmitate-BSA complex into hexane, the magnitude being dependent on the initial $\text{V}$ value (moles palmitate bound/mole BSA). Beginning with [¹⁴C]-palmitate in hexane, chlorophenoxyisobutyrate (2 mM) decreased the moles palmitate bound/mole of BSA by 16% at $\text{V}$ = 0.2, and 34% at $\text{V}$ = 3.0.