Inhibition of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced mouse lung tumor formation by FGN-1 (sulindac sulfone)

The sulfone derivative of the non-steroidal anti-inflammatory drug (NSAID), sulindac, has been reported to inhibit mammary and colon tumor formation in rodent models of chemically-induced carcinogenesis. Unlike its parent compound, this metabolite lacks cyclo-oxygenase inhibitory activity. A tumor induction protocol, consisting of NNK administration in the drinking water over several weeks to model chronic human exposure, was used to test whether the sulfone (called FGN-1) could inhibit the formation of primary lung tumors in mice. A total of 150 female, AIN76A-fed, A/J mice received 9 mg of NNK each. Concentrations of FGN-1 that had been previously determined not to affect body weight gain were added to the food at levels of 0, 250, 500 and 750 mg/kg of diet (30 mice/group) starting 2 weeks before NNK administration and continuing for 22 weeks. At that time pleural surface tumors were counted. Tumor incidence decreased significantly from 96 % in the control diet and 93% in the 250 FGN-1 mg/kg diet to 63 and 67% in the 500 and 750 mg FGN-1/kg diet groups, respectively (P < 0.001 by chi-square analysis). Lung tumor multiplicity decreased from 18.1+/-3 tumors/ mouse (mean+/-SEM, control diet) to 12.3+/-3 (250), 5.3+/-1 (500) and 2.1+/-1 (750) (P < 0.0005 by post hoc ANOVA). In previous studies using this carcinogenesis protocol, the maximum tolerated dose of sulindac inhibited lung tumor multiplicity by no more than 50% with no effect on incidence. This dose-dependent reduction in tumorigenesis by a non-toxic dose of FGN-1 indicates a strong chemopreventive activity against experimental induction of lung carcinogenesis. The greater potency of the sulfone over sulindac and its lack of toxic side effects because of its inability to affect cyclo-oxygenase activity suggests that clinical testing in individuals at high risk for lung cancer should be considered.     

Determination of plasma digoxin in newborn infants. Practical applications

Measurement of plasma digoxin concentrations in infants after three increasing dosage levels shows that the optimal dose of this glycoside in 20 microgram/kg/day, i.e. a loading dose of 20 microgram/kg followed every 8 hours by a maintenance dose of 7 microgram/kg. The plateau concentration achieved is 3.0 +/- 0,5 ng/ml 8 hours after the last administration. When digoxin levels exceed 5 ng/ml (overdosage, renal failure or low body weight), toxic manifestations occur.     

The effects of phenethyl isothiocyanate, N-acetylcysteine and green tea on tobacco smoke-induced lung tumors in strain A/J mice

Male and female strain A/J mice were exposed to a mixture of cigarette sidestream and mainstream smoke at a chamber concentration of total suspended particulates of 82.5 mg/m3. Exposure time was 6 h/day, 5 days/week for 5 months. The animals were allowed to recover for another 4 months in filtered air before sacrifice and lung tumor count. Male animals were fed either 0.2% N-acetylcysteine (NAC) or 0.05% phenethyl isothiocyanate (PEITC) in diet AIN-76A with 5% corn oil added. Female animals received normal laboratory chow and were given a 1.25% extract of green tea in the drinking water. Corresponding control groups were fed diets without NAC or PEITC or given plain tap water. Exposure to tobacco smoke increased lung tumor multiplicity to 1.1-1.6 tumors/lung, significantly higher than control values (0.5-1.0 tumors/lung). None of the putative chemopreventive agents (NAC, PEITC or green tea extract) had a protective effect. In positive control experiments, PEITC significantly reduced both lung tumor multiplicity and incidence in mice treated with the tobacco smoke-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). In mice treated with three different doses of urethan and fed NAC in the diet, a significant reduction in lung tumor multiplicity was found only at one dose level. Green tea extract did not reduce lung tumor multiplicity in animals treated with a single dose of NNK. It was concluded that successful chemoprevention of tobacco smoke-induced lung tumorigenesis might require administration of several chemopreventive agents rather than just a single one.     

Butylated hydroxytoluene exposure is necessary to induce lung tumors in BALB mice treated with 3-methylcholanthrene

Chronic butylated hydroxytoluene (BHT) treatment after a single administration of a carcinogen increases lung tumor multiplicity in some inbred strains of mice. We report that BALB/cOla and BALB/cByJ mice given a low dose (10 microg/g of body weight) of 3-methylcholanthrene (MCA) develop no lung tumors unless this is followed by chronic BHT exposure. Slightly higher MCA doses (15 and 25 microg/g) induce low lung tumor multiplicities (0.6 and 1.9 tumors/mouse, respectively) that are increased 12-26-fold by chronic BHT administration. This low-dose MCA/BHT model in BALB mice will facilitate the identification of genes regulating susceptibility to lung tumor promotion and pulmonary chemopreventative agents that act at a postinitiation site.     

Inhibition of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone-induced lung tumorigenesis by dietary olive oil and squalene

Epidemiological studies have suggested that frequent olive oil consumption may be a protective factor against lung cancer formation. Squalene, a characteristic compound in olive oil, is an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and has been proposed to inhibit the farnesylation of ras oncoproteins. The present study investigated the effect of dietary olive oil and squalene in a mouse lung tumorigenesis model. Female A/J mice were fed AIN-76A diets containing 5% corn oil (control), 19.6% olive oil, or 2% squalene starting at 3 weeks before a single dose of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) (103 mg/kg, i.p.). Animals were maintained on their respective diets throughout the study. At 16 weeks after NNK administration, 100% of the mice in the control group had lung tumors with a tumor multiplicity of 16 tumors per mouse. The olive oil and squalene diets significantly (P < 0.05) decreased the lung tumor multiplicity by 46 and 58%, respectively. The squalene diet significantly (P < 0.05) decreased lung hyperplasia by 70%. In mice fed a diet containing 2% squalene for 3 weeks, the activation of NNK was increased by 1.4- and 2.0-fold in lung and liver microsomes, respectively, but its relationship to the inhibition of carcinogenesis is not clear. These results demonstrate that dietary olive oil and squalene can effectively inhibit NNK-induced lung tumorigenesis.     

Pretreatment with somatostatin analog SMS 201-995 potentiates growth hormone (GH) responsiveness to GH-releasing factor in short children

Previous studies in children have shown inconsistent, poorly reproducible GH responses to exogenous GH-releasing factor (GRF), with wide individual variability. In the present study, we tested the hypothesis that prior administration of the long-acting somatostatin analog, SMS 201-995 (SMS), will enhance GH responsiveness to a subsequent GRF challenge. Two study protocols were employed in 37 children with short stature [M = 31, F = 6, ages 11.8 +/- 1.6 yr (mean +/- SEM), height -2.25 +/- 0.55 SDS (SD scores)]. In both studies, each subject served as his/her own control. In the first study, which was designed to determine optimal SMS dose and regimen, SMS, in doses ranging from 0.8-2.2 micrograms/kg sc, was randomly administered or omitted at 0800 h after an overnight fast, and a GRF bolus (50 micrograms, iv) was given 4 h later. In the second study, we employed a protocol identical to study 1 except for the use of standard doses of SMS (1 microgram/kg, sc) and GRF (1 microgram/kg, iv) and an additional 1-h delay of the GRF injection. Plasma GH levels were measured every 20 min from 0800 h until 2 h after the GRF injection in both studies. In study 1 (n = 12; M = 10, F = 2), SMS significantly suppressed spontaneous GH secretion (expressed as the mean +/- SEM GH AUC during the 4-h SMS-GRF interval, AUC 1:2.2 +/- 0.4 vs. 6.2 +/- 0.9 micrograms/L.h; P < 0.001), GH responsiveness to GRF (GH AUC during the 2 h after the GRF injection, AUC 2: 41.5 +/- 7.8 vs. 85.0 +/- 13.5 micrograms/L.h; P < 0.001), and the GH peak response (17.4 +/- 3.1 vs. 36.0 +/- 6.2 micrograms/L; P < 0.001), compared to control tests. In contrast, in study 2 (n = 25; M = 21, F = 4), whereas spontaneous GH secretion was still suppressed during the 5-h SMS-GRF interval (AUC 1:3.8 +/- 0.4 vs. 7.4 +/- 1.1 micrograms/L.h; P < 0.001), both the GH peak response (56.7 +/- 5.5 vs. 30.5 +/- 3.0 micrograms/L; P < 0.0001) and the GH AUC (AUC 2: 103.7 +/- 10.3 vs. 77.5 +/- 6.8 micrograms/L.h; P < 0.05) after GRF administration were significantly augmented by pretreatment with SMS, compared to control tests. Taken together, these results indicate that a priming SMS dose of 1 microgram/kg has a significant permissive effect on GH responsiveness to exogenous GRF administered 5 h later.(ABSTRACT TRUNCATED AT 400 WORDS)     

Murine hepatic p53, RB, and CDK inhibitory protein expression following acute 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure

This study examined the expression of murine hepatic tumor suppressor and cell cycle inhibitory proteins in response to acute 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) dosing in Balb/c mice. Elevations in expression of p53, retinoblastoma (Rb) protein, p16Ink4, p21Waf1 and p27Kip1 were observed six days after a single dose of 0.25, 0.5, 1 or 2 micrograms TCDD/kg. These data suggest that the TCDD-induced inhibition of hepatocyte proliferation in vivo could be attributed to the expression of cell cycle inhibitory proteins.     

Cardiopulmonary response to dopamine in chronically catheterized neonatal lambs

Seven neonatal lambs were chronically catheterized. An electromagnetic flow probe was placed around the main pulmonary artery, and the ductus arteriosus ligated. After recovery, dopamine's effect was tested at 10 doses over the range 1--400 micrograms/kg/min in 12 studies, at ages 3 to 16 days. Pulmonary vascular resistance (PVR) increased from 0.093 +/- 0.01 to 0.14 +/- 0.02 mm Hg/ml/kg/min at the highest dose. Systemic vascular resistance (SVR) was unchanged at doses less than 20 micrograms/kg/min, but increased 99% from 0.38 +/- 0.04 to 0.79 +/- 0.08 mm Hg/ml/kg/min (P less than 0.005) at 200--400 micrograms/kg/min. The ratio PVR/SVR increased 18% from 0.26 +/- 0.32 to 0.32 +/- 0.05 at a dose of 17--20 mg/kg/min, then declined to 0.19 +/- 0.03 at 200--400 microgram/kg/min (P less than 0.05). Pulmonary blood flow was unchanged. Left atrial pressure increased sharply at doses above 50 micrograms/kg/min (P less than 0.005). Transient bradyarrhythmia occurred in 9 of 12 studies at infusion rates of 50--200 micrograms/kg/min. Heart rate did not change until recovery when it increased (48%) from 181 to 292 (P less than 0.005). These data suggest that the dopamine response in the intact neonate is complex with divergent and dose-dependent effects on the pulmonary and systemic circuit.     

Majonoside-R2, a major constituent of Vietnamese ginseng, attenuates opioid-induced antinociception

The effects of majonoside-R2 on antinociceptive responses caused by the mu-opioid receptor agonist morphine and the selective kappa-opioid receptor agonist U-50, 488H were examined by the tail-pinch test in mice. Intraperitoneal (IP) or intracerebroventricular (ICV) injection of majonoside-R2 (3.1-6.2 mg/kg, IP or 5-10 micrograms/mouse, ICV) and diazepam (0.1-0.5 mg/kg, IP or 0.5-1.0 microgram/mouse, ICV), as well as an opioid receptor antagonist naloxone (2 mg/kg, IP or 5 micrograms/mouse, ICV), dose-dependently attenuated the antinociception caused by subcutaneously administered morphine and U-50,488H. Moreover, when co-administered ICV or intrathecally (IT) with morphine (4 micrograms/mouse) or U-50,488H (60 micrograms/mouse), majonoside-R2 (5-20 micrograms/mouse) also exhibited antagonism against the antinociceptive action of these opioid receptor agonists in the tail-pinch test. The inhibitory effects of majonoside-R2 (10 micrograms/mouse, ICV) and diazepam (1 microgram/mouse, ICV) were reversed by flumazenil (2.5 micrograms/mouse, ICV), a selective benzodiazepine receptor antagonist, and picrotoxin (0.25 microgram/mouse, ICV), a GABA-gated chloride channel blocker. These results suggest that majonoside-R2 attenuates the opioid-induced antinociception by acting at the spinal and supraspinal levels, and that the GABAA receptor complex at the supraspinal level is involved in the effect of ICV administered majonoside-R2.     

Peroxynitrite formation in focal cerebral ischemia-reperfusion in rats occurs predominantly in the peri-infarct region

The plasma pharmacokinetics of danofloxacin administered at 1.25 mg kg-1 body weight by the intravenous and intramuscular routes were determined in sheep. Tissue distribution was also determined following administration by the intramuscular route at 1.25 mg kg-1 body weight. Danofloxacin had a large volume of distribution at steady state (Vdss) of 2.76 +/- 0.16 h (mean +/- S.E.M.) L kg-1, an elimination half-life (t1/2 beta) of 3.35 +/- 0.23 h, and a body clearance (C1) of 0.63 +/- 0.04 L kg-1 h-1. Following intramuscular administration it achieved a maximum concentration (Cmax) of 0.32 +/- 0.02 microgram mL-1 at 1.23 +/- 0.34 h (tmax) and had a mean residence time (MRT) of 5.45 +/- 0.19 h. Danofloxacin had an absolute bioavailability (F) of 95.71 +/- 4.41% and a mean absorption time (MAT) of 0.81 +/- 0.20 h following intramuscular administration. Mean plasma concentrations of > 0.06 microgram mL-1 were maintained for more than 8 h following intravenous and intramuscular administration. Following intramuscular administration highest concentrations were measured in plasma (0.43 +/- 0.04 microgram mL-1), lung (1.51 +/- 0.18 micrograms g-1), and interdigital skin (0.64 +/- 0.18 microgram g-1) at 1 h, duodenal contents (0.81 +/- 0.40 microgram mL-1), lymph nodes (4.61 +/- 0.35 micrograms g-1), and brain (0.06 +/- 0.00 microgram mL-1) at 2 h, jejunal (10.50 +/- 4.31 micrograms mL-1) and ileal (5.25 +/- 1.67 micrograms mL-1) contents at 4 h, and colonic contents (8.94 +/- 0.65 micrograms mL-1) at 8 h.     

Ocular pharmacokinetics of orally administered azithromycin in rabbits

Azithromycin was orally administered to Dutch-belted rabbits following extracapsular lens extraction in one eye. At various times the animals were sacrificed, and serum and ocular tissues were obtained for drug level determination by HPLC-EC. Following a single dose, peak levels of drug in ocular tissues were measured within 8 hours (cornea > 0.5 micrograms/g [15mg/kg]; > 1.5 micrograms/g [3Omg/kg]). Highest levels were obtained in iris and ciliary body ( > 15 micrograms). Measurable tissue levels persisted for at least 120 hours. Trough levels increased proportionately during drug multiple dose administration. Five days following five daily 15mg/kg doses, corneal levels exceeded 0.5 micrograms/g, and iris and ciliary levels were higher than 15 micrograms/g. Aqueous humor and serum levels were equivalent. Vitreous humor levels, though higher than aqueous humor, were consistently < 1 microgram/ml. Extracapsular cataract extraction did not significantly affect drug uptake.     

Physical dependence produced by dihydroetorphine in mice

Using various administration schedules, the physical dependence produced by dihydroetorphine (DHE) was compared with that of morphine in mice. Physical dependence, evaluated by naloxone-precipitated withdrawal signs, did not develop following daily treatment with DHE (10, 20, 100 and 1000 micrograms/kg, i.p. or 30, 100 and 1000 ng/mouse, i.c.v.) for 6 d. However, 5 repeated injections of DHE (10 micrograms/kg, i.p.) at 1 or 2 h intervals did produce physical dependence and the dependent state disappeared after 2 h. Accordingly, it was demonstrated that a sufficient degree of antinociceptive activity needed to be maintained, longer than several hours, for the development of physical dependence on DHE and that the duration of the dependent state was very short. In the single dose suppression test, a single dose of DHE completely suppressed the natural withdrawal signs that appeared following abstinence in morphine-dependent animals without reappearance of significant withdrawal signs, indicating the suitability of DHE as a substitute for morphine. The characteristic properties of DHE, the extremely potent antinociceptive effect and minimal dependence, indicate the separation of the antinociceptive effect from dependence, and suggest that it may be possible to develop a novel drug which may be safely used in clinical situations.     

Effect of radiation therapy on small-cell lung cancer is reduced by ubiquinone intake

The effect of oral ubiquinone (Q10) intake on the in vivo response of tumors to single dose radiotherapy was examined. The human small-cell lung cancer (SCLC) line CPH 054A, which is sensitive to relatively low doses of X-radiation, was grown as subcutaneous transplants in the flanks of nude nu/nu mice. When macroscopical growth was established, groups of mice received either 10, 20 or 40 mg/kg Q10 in 30 mL soy oil intragastrically daily on 4 consecutive days. Controls received either 30 mL of pure soy oil or nothing. Three h after the last dose half of the tumors in each group received a single radiation dose of 5 Gy, using a 300 kV therapeutic unit. The macroscopic growth pre- and posttreatment was analyzed according to a transformed Gompertz algorithm using the software program GROWTH. Treatment with Q10 or soy oil alone had no effect on tumor growth compared with untreated controls. Groups of tumors that received Q10 and radiotherapy had a significantly lower specific growth delay (SGD) than the radiotherapy-only groups. This effect was significant at 40 mg/kg and borderline at 20 mg/kg, whereas at 10 mg/kg no radioprotection was seen. We conclude that systemic Q10 reduces the response to single dose tumor irradiation inxenotransplanted human SCLC tumors.     

Interferon-gamma differentially regulates antigen-processing functions in distinct endocytic compartments of macrophages with constitutive expression of class II major histocompatibility complex molecules

Treatment of pregnant female Sprague-Dawley rats on Gestational Day 15 with a single oral dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (0.5, 1.0, or 2.0 micrograms/kg) or indole-3-carbinol (I3C, 1.0 or 100 mg/kg), an aryl hydrocarbon (Ah) receptor agonist which is found in cruciferous vegetables, resulted in reproductive abnormalities in the male offspring (three to five litters in each treatment group). Anogenital distance and crown to rump length were altered by both compounds; however, the timing of the effects (Day 1 or 5) was variable and the responses were not necessarily dose-dependent. In 62-day-old offspring, seminal vesicle (24 to 26%), prostate (32 to 44%), testicular parenchymal (14%), and epididymal weight (19%) were decreased by one or more doses of TCDD. In contrast, I3C at one or more doses decreased daily sperm production/g testicular parenchyma (13 to 20%) and daily sperm production/testis (22%). Total number of sperum in the epididymis was significantly decreased (30 to 33%) in rats perinatally exposed to TCDD and this was due to a decreased (49 to 51%) number of sperm in the tail of the epididymis. Perinatal exposure to I3C did not affect any of these parameters. TCDD did not affect epididymal transit time of sperm through the complete epididymis at any of the doses (0.5 to 2.0 micrograms/kg). However, at the two highest doses (1.0 and 2.0 micrograms/kg), TCDD increased epididymal transit rate of sperm through the tail of the epididymis by 33 and 37%, respectively. In contrast, primarily due to decreased transit rate (39%) of sperm through the head plus body of the epididymis. I3C (1 mg/kg) significantly increased total epididymal transit time by 31%. In conclusion, perinatal exposure of pregnant rats to I3C, an Ah receptor agonist similar to TCDD, causes reproductive abnormalities in male rat offspring; however, I3C and TCDD elicited both common and different responses.     

Optimal scheduling of interleukin 12 and chemotherapy in the murine MB-49 bladder carcinoma and B16 melanoma

The antitumor activity of interleukin (IL)-12, a naturally occurring cytokine, has been demonstrated in several murine solid tumors. Animals bearing established B16 melanoma or MB-49 bladder carcinoma were used to study the most effective scheduling of recombinant murine IL-12 (rmIL-12), along with systemic chemotherapy. rmIL-12 (0. 45, 4.5, or 45 microgram/kg) was more effective as a single agent when administered to mice bearing the MB-49 bladder carcinoma at the highest dose for 11 doses rather than for 5 doses. In combination with chemotherapy (Adriamycin, cyclophosphamide, or 5-fluorouracil), rmIL-12 administration did not increase the toxicity of the chemotherapy, and there was increased antitumor activity with each rmIL-12-drug combination. Administering rmIL-12 (45 microgram/kg) on days 4-14, along with Adriamycin, cyclophosphamide, or 5-fluorouracil on days 7-11, resulted in 2.2-2.7-fold increases in tumor growth delay, compared with the chemotherapy alone against the primary tumor, and a marked decrease in the number of lung metastases on day 20. Because the B16 melanoma grows more slowly than the MB-49 bladder carcinoma, allowing multiple courses of chemotherapy, cyclophosphamide could be administered. The rmIL-12 (45 microgram/kg)-cyclophosphamide combination regimen that was most effective overlapped 2 days with the terminal portion of the chemotherapy treatment. There was a parallel increase in the response of the primary tumor and metastatic disease to the lungs. Administration of rmIL-12 to animals bearing the MB-49 bladder carcinoma or the B16 melanoma was compatible with coadministration of chemotherapy at full dose without additional toxicity.     

A mutation in the neurofibromatosis type 2 tumor-suppressor gene, giving rise to widely different clinical phenotypes in two unrelated individuals

Polychlorinated biphenyls (PCBs) are industrial chemicals that are long-lasting global environmental contaminants. PCBs have been reported to adversely affect reproduction in laboratory and wild animals by reducing the incidence of breeding and the survival rate of young. The present study was undertaken to determine the toxic potential of PCBs on in vitro fertilization (IVF) in the mouse. Aroclor 1221, 1254, and 1268, and 3, 3', 4, 4'-tetrachlorobiphenyl (TCB), a PCB congener, were added to IVF medium at various concentrations (0.01, 0.1, 1, and 10 micrograms/mL). Cumulus masses containing oocytes were obtained from superovulated B6D2F1 mice and cultured in medium containing PCB to which capacitated sperm were added. Oocytes were assessed for fertilization 20 to 24 h after insemination. A-1221, A-1268, and TCB reduced the fertilization rate at the 1 microgram/mL and 10 micrograms/mL doses, while inhibition of fertilization by A-1254 reached significance at 0.1 microgram/ml. Furthermore, all of these chemicals caused an increased incidence of degenerative ova and abnormal 2-cell embryos at the higher dose levels (1 microgram/mL and 10 micrograms/mL). The results suggest that higher dosages of PCB and TCB adversely affect fertilization and cause an increased incidence of degeneration of oocytes and abnormality in the early mouse embryos.     

Effects of long-term treatment with Serenoa repens (Permixon) on the concentrations and regional distribution of androgens and epidermal growth factor in benign prostatic hyperplasia

Nitrates act, in part, by causing systemic venodilation. In addition, nitrates lead to dilation of arterial conductance vessels. The maximal dilation capacity and threshold of arterial conductance vessels have so far not been examined thoroughly. Therefore, we tested the radial artery diameter before and after i.v. nitroglycerin infusions at increasing dosages (0.015, 0.05, 0.15, 0.5, and 1.5 micrograms/kg/min), 7 min each dose in 28 patients with suspected coronary artery disease (mean age +/- SEM 58 +/- 2 years) using a high resolution ultrasound devise. The low doses of 0.05 and 0.15 microgram/kg/min, equal to dose of 2.5 mg/12 hours and 7.5 mg/12 hours in a patient with 70 kg, led to substantial increases in the cross sectional luminal area of the radial artery of 14.8 +/- 1.5% and 29.3 +/- 2.2%*, (*p < 0.05 vs baseline). The maximal increase (dilatory capacity) was 53.8 +/- 3.8% (mean diameter at baseline: 2.7 +/- 0.1 mm, maximal 3.4 +/- 0.1 mm, p < 0.001). The nitrate sensitivity of the radial artery was estimated by calculation of the ED50, the dose that caused half-maximal dilation of the radial artery. The ED50 of the radial artery was 0.13 +/- 0.003 microgram/kg/min. In conclusion, nitroglycerin leads to a dose dependent dilatation of peripheral conductance vessels. Low doses of 0.05 and 0.15 microgram/kg/min lead to significant arterial dilation. The maximal dilatory capacity of the radial artery is 53.8 +/- 3.5%.     

Inhibition of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone mouse lung tumorigenesis by arylalkynes, mechanism-based inactivators of cytochrome P450

Arylalkynes such as 4-phenyl-1-butyne (PBY), 5-phenyl-1-pentyne (PPY) and 2-ethynylnaphthalene (2-EN) are suicide inhibitors of cytochrome P450 enzymes. Arylalkyl isothiocyanates such as 6-phenylhexyl isothiocyanate (PHITC) are structurally related to arylalkynes and are known to inhibit the cytochrome P450 mediated metabolic activation and tumorigenicity of a tobacco-specific lung carcinogen, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). In this study, we compared the ability of PBY, PPY, 2-EN and PHITC to inhibit A/J mouse lung tumorigenesis by NNK. Groups of 20 female mice were gavaged with 5 mumol of arylalkyne or PHITC in corn oil. Two hours later they were given a single i.p. injection of 10 mumol NNK. The mice were killed 16 weeks later. PPY and PHITC were both potent inhibitors of tumorigenesis by NNK, reducing lung tumor multiplicity from 8.35 tumors per mouse to 0.40 and 0.35 respectively. PBY and 2-EN also significantly inhibited tumor multiplicity. The results of this study demonstrate that arylalkynes and PHITC are potent inhibitors of NNK induced lung tumorigenesis in A/J mice, consistent with the hypothesis that inhibition of specific cytochrome P450 enzymes is involved in inhibition of tumorigenesis.     

Bispecific antibody-mediated lysis of placental and germ cell alkaline phosphatase targeted solid tumors in immunocompetent mice

Recently, an immunocompetent in vivo mouse model was developed based on germ cell alkaline phosphatase (GCAP) transgenic (FVB/N x C3H) mice in which both placental alkaline phosphatase (PLAP)+ and GCAP+ solid MO4 tumors develop. A bispecific anti-PLAP/GCAP anti-mouse CD3 antibody (Ab) 7E8 x 7D6, previously shown to induce efficient dose-dependent T-cell proliferation and PLAP+ tumor cell lysis in the presence of recombinant IL-2 and the anti-mouse CD3 Ab 7D6, was used in this report in in vivo lysis experiments targeting GCAP+ tumors grown in GCAP+ transgenic mice. Mice received injections i.v. twice a week with PBS (group 1) or with 10 micrograms of the bispecific Ab 7E8 x 7D6, either alone (group 2) or combined with 1 microgram of the anti-CD3 Ab 7D6 (group 3), starting 7 days after the tumor inoculation. A fourth group received a local treatment with mouse splenocytes precoated with 10 micrograms 7E8 x 7D6 and 1 microgram 7D6. In between Ab injections, groups 2, 3, and 4 received 10(4) units recombinant IL-2 (i.v.) every day. Two weeks of treatment with the bispecific Ab either alone or combined with 7D6 resulted in a significant decrease of GCAP+ tumor cells in groups 2 and 3 (4 +/- 3% and 10 +/- 11% GCAP+ cells/tumor) as compared to the nontreated tumors (95 +/- 5% GCAP+ cells), although tumor volumes were not significantly different (12 +/- 15 cm3 and 14 +/- 11 cm3 versus 16 +/- 7 cm3). Apparently, the elimination of GCAP+ cells from the tumor seemed to favor conditions enabling the outgrowth of the few GCAP- cells originally present in the tumor inoculate. In contrast, tumor volumes in group 4 (local treatment) were significantly smaller (P < 0.03; 5 +/- 10 cm3, 8 +/- 11% GCAP+ cells) as compared to the nontreated group, probably due to the presence of higher amounts of Ab and infiltrated activated T cells (567 +/- 322 CD5+ cells/mm2) capable of secreting cytostatic cytokines like tumor necrosis factor alpha and IFN-gamma as compared to groups 2 and 3 (266 +/- 135 and 198 +/- 86 CD5+ cells/mm2, respectively). In summary, this study clearly demonstrated that bispecific antibodies specifically concentrate cytotoxic T cells into a solid tumor in vivo, with subsequent elimination of the targeted tumor cell.     

Relationship between cytochrome P450 2E1 and acetone catabolism in rats as studied with diallyl sulfide as an inhibitor

Previous studies have demonstrated that cytochrome P450 2E1 (P450 2E1) catalyzes the oxidation of acetone in vitro. The present study was designed to determine the importance of P450 2E1 in the catabolism of acetone in rats using diallyl sulfide (DAS) as an inhibitor of this enzyme. After a single intragastric dose of DAS, blood samples were collected from rats at different time points, and blood acetone concentrations were measured by gas chromatography. In a low DAS dose (50 mg/kg body weight) group, the maximum acetone level of 6-fold higher than the normal level was reached at 6 hr; the acetone level returned to normal at 48 hr. In a high dose (200 mg/kg) group, the maximum acetone level of 9-fold higher than the normal level was reached at 12 hr; the acetone level returned to normal at 60 hr. The turnover time and fractional turnover rate of elevated acetone were 15.8 +/- 0.5 hr and 0.054 +/- 0.001 hr-1, respectively, for the low dose, and 19.2 +/- 0.6 hr and 0.046 +/- 0.005 hr-1, respectively, for the high dose. In a chronic experiment, DAS (50 and 200 mg/kg, i.g.) was given to rats daily for 29 days, and elevated blood acetone levels were observed during the entire experimental period: 2.0 to 2.8 micrograms/mL for the low dose and 3.4 to 3.9 micrograms/mL for the high dose at 24 hr after the 1st, 7th, 14th and 28th doses versus 0.8 to 0.9 micrograms/mL for the control. The increase of blood acetone level was closely related to the decreases of N-nitrosodimethylamine (NDMA) demethylase activity and P450 2E1 content in liver microsomes. Consistent with the lack of cumulative effect from the multiple doses of DAS on acetone level, rather stable levels of the DAS metabolites, diallyl sulfoxide (45.0 micrograms/mL, range: 33.8 to 58.6 micrograms/mL) and diallyl sulfone (11.7 micrograms/mL, range: 6.9 to 15.6 micrograms/mL), were observed at 24 hr after the 1st, 7th, 21st and 28th doses with DAS (200 mg/kg) in the chronic experiment. It is likely that the inactivation and inhibition of P450 2E1 by DAS and its metabolites block the oxidation of acetone and cause its elevation in blood. The results strongly suggest an important role of P450 2E1 in acetone catabolism under physiological conditions.