Impact of intraperitoneal chemotherapy after gastrectomy with positive cytological findings in peritoneal washings.

BACKGROUND: There is no standard treatment available for gastric cancer patients whose sole 'non-curative factor' is positivecytological findings in peritoneal washings (CFPW). The aim of this study was to examine the safety, pharmacokinetics and efficacy for free intraperitoneal cancer cells of intraperitoneal chemotherapy with paclitaxel after gastrectomy with en bloc D2 lymph node dissection in cases of gastric cancer with positive CFPW. METHODS: Ten patients with gastric cancer who underwent gastrectomy and systemic lymphadenectomy with D2 dissection, without any other non-curative factors besides positive CFPW, were treated with early postoperative intraperitoneal paclitaxel. Intra-chemotherapeutic toxicity and operative complications were measured using NCI-CTC version 3.0. Intraperitoneal and plasma paclitaxel concentrations were measured using a high-performance liquid chromatographic assay. RESULTS: Grade 3/4 toxic effects included anemia (20%) and neutropenia (10%) that required no treatment. Operative complications were, for example, superficial surgical site infections (10%) that were treated with antibiotics. No viable cancer cells were observed in the intra-abdominal fluid 24 h after intraperitoneal administration of paclitaxel. The intraperitoneal/plasma area under the drug concentration-time curve ratio was 2,003.3:1. CONCLUSION: Intraperitoneal chemotherapy with paclitaxel is a safe and effective treatment modality for free intraperitoneal cancer cells.

Removal of digoxin by column for specific adsorption of beta(2)-microglobulin: a potential use for digoxin intoxication.

BACKGROUND: A beta(2)-microglobulin adsorption column used for the treatment of dialysis-related amyloidosis removes serum beta(2)-microglobulin by recognition of lipophilic residue in the protein. No data are available for the adsorption of the highly lipophilic drug digoxin. METHODS: In vivo clearance of digoxin with the beta(2)-microglobulin column was measured by a single use of the column in 8 patients receiving hemodialysis with a therapeutic level of digoxin. In vitro adsorption was evaluated by use of incubation with adsorbent of the column and digoxin or ranitidine, a hydrophilic drug. Clearance with the beta(2)-microglobulin column was further compared with that obtained by use of activated charcoal in the dogs intoxicated with digoxin. RESULTS: Digoxin concentration was reduced from 1.11 +/- 0.25 ng/mL to 0.57 +/- 0.15 ng/mL at 240 minutes after initiation of hemoperfusion with the column in the patients. Digoxin clearance with the beta(2)-microglobulin column was about 145 +/- 20 mL/min, with a blood flow rate of 160 to 220 mL/min (80% of plasma flow rate). Eighty-five percent of digoxin was adsorbed in vitro, and the capacity of the beta(2)-microglobulin column was not saturated until a toxic level was reached (50 ng/mL). This value was higher than that obtained with use of charcoal. In dogs with digoxin intoxication, digoxin clearance was 38.9 +/- 1.5 mL/min, with a blood flow rate of 50 mL/min (95% of plasma flow rate), which was almost twice as that achieved with charcoal. The degree of thrombocytopenia and leukopenia was small with use of the beta(2)-microglobulin column. CONCLUSION: These data suggested that the beta(2)-microglobulin column selectively adsorbs digoxin. This column is a promising tool for the treatment of digoxin intoxication, especially in patients undergoing hemodialysis.

Different effects of St John's wort on the pharmacokinetics of simvastatin and pravastatin.

OBJECTIVE: St John's Wort, a widely used herbal product, is an inducer of CYP3A4 and it decreases blood concentrations of CYP3A4 substrates. The effects of St John's Wort on the pharmacokinetics of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors simvastatin (an inactive lactone pro-drug) and pravastatin were determined in this study. METHODS: Sixteen healthy male subjects (n = 8 in group 1 and n = 8 in group 2) took a St John's Wort caplet (300 mg) or matching placebo three times a day for 14 days in a double-blind, crossover study. On day 14, a single oral dose of 10 mg simvastatin and 20 mg pravastatin was given to subjects in group 1 and group 2, respectively. Blood samples were obtained during a 24-hour period after the administration of each drug. RESULTS: Repeated St John's Wort treatment tended to lower plasma simvastatin concentration and significantly (P <.05) lowered concentrations of simvastatin hydroxy acid, its active metabolite. The peak concentration in plasma (ratio, 0.72 of placebo) of simvastatin hydroxy acid tended to be decreased and its area under the plasma concentration-time curve between time zero and 24 hours after administration (ratio, 0.48 of placebo) was significantly decreased (P <.05) by St John's Wort. On the other hand, St John's Wort did not influence plasma pravastatin concentration. No significant differences were observed in the elimination half-life of simvastatin or pravastatin between the placebo and St John's Wort trials. CONCLUSIONS: This study showed that St John's Wort decreases plasma concentrations of simvastatin but not of pravastatin. Because simvastatin is extensively metabolized by CYP3A4 in the intestinal wall and liver, which are induced by St John's Wort, it is likely that this interaction is partly caused by the enhancement of the CYP3A4-mediated first-pass metabolism of simvastatin in the small intestine and liver.

Structure-activity relationship in vasoconstrictor effects of sarafotoxins and endothelin-1.

Sarafotoxins (SRTa, SRTb and SRTc) as well as endothelin-1 (ET-1) produced vasoconstrictions in rat thoracic aorta, rat isolated perfused mesentery and pithed rat in various of extents. The potency was ET-1 greater than SRTb greater than SRTa greater than SRTc at lower doses, but SRTb greater than ET-1 greater than SRTa greater than SRTc at higher doses. [Nitrophenylsulfenylated Trp21]SRTb and SRTb(1-19) caused no vasoconstriction. Either the reduction and carboxymethylation of Cys residues, the destruction of the intramolecular loop or the production of the non-natural disulfide bond, eliminated the constrictor activity. These results indicate that Trp21 and the intramolecular loop structure are essential, and Lys9 and Tyr13 may play some important roles for the vasoconstrictor activity of these peptides.

Vasodilator effects of sarafotoxins and endothelin-1 in spontaneously hypertensive rats and rat isolated perfused mesentery.

Sarafotoxins (SRTa, SRTb and SRTc) and ET-1 produced a potent vasodilator effect in spontaneously hypertensive rats in vivo and in rat isolated perfused mesenteries in vitro. Among these peptides SRTc demonstrated the most potent vasodilator activity, and was three times more active than SRTa in both preparations. These peptides induced endothelium-dependent vasodilatation in vitro and pretreatment with methylene blue inhibited this effect, while exposure to the antagonists of other vasodilators did not. In contrast, [nitrophenylsulfenylated Trp21]SRTc, SRTc(1-18) and reduced and S-carboxymethylated SRTc caused no vasodilatation in either animal model; the vasodilator effect of acetylated SRTc was less potent than that of SRTc. These results suggest that (i) the vasodilatations of these peptides may be exerted through the release of endothelium derived relaxing factor; (ii) the C-terminal Trp21 and disulfide bonds are essential; and (iii) the N-terminal amino group plays an important role in vasodilator activity.

Chronotherapy with active vitamin D3 in aged stroke-prone spontaneously hypertensive rats, a model of osteoporosis.

The chronotherapeutic effects of 1-alpha-(OH) vitamin D3, a pro-drug of 1,25(OH)2 vitamin D3 (1,25(OH)2D3), were evaluated by repeated dosing of the drug in aged stroke-prone spontaneously hypertensive male rats, a model of osteoporosis. Animals (7 months old) were kept in rooms with a 12-h light/dark cycle. Drug (0.5 microg/kg) or vehicle was given once daily at 2 or 14 h after lights on for 3 months. The severity of adverse effects such as body weight loss, hypercalcemia and hyperphosphatemia was significantly less when the drug was given at 14 h after lights on (14 HALO). Serum 1,25(OH)2 vitamin D3 concentrations of 2 h after lights on (2 HALO) group and 14 HALO group did not differ significantly after dosing. The decrease in parathyroid hormone (PTH) level 12 weeks after the start of the study was greater in the 14 HALO group than in the 2 HALO group. Urinary excretion of inorganic Ca and P in the 2 HALO group was greater than that in the 14 HALO group. Urinary excretion of deoxypyridiniline, an index of the bone resorption capacity of osteoclasts, was much suppressed in the 14 HALO group, suggesting that the efficacy of vitamin D3 for suppressing bone resorption might vary with the dosing time. The increase in bone density of both femurs, determined by dual-energy X-ray absorption at the end of the study, was greater in the 14 HALO group than in the 2 HALO group. This is the first study to show the dosing time-dependent efficacy and toxicity of active vitamin D3 in an animal model of osteoporosis. These results indicate that a chronopharmacological approach is beneficial for establishing a more effective and/or safer regimen of active vitamin D3 for the treatment of osteoporosis.

Structure-activity relationships of sarafotoxins: chemical syntheses of chimera peptides of sarafotoxins S6b and S6c.

The three chimera peptides of sarafotoxins S6b (SRTb) and S6c (SRTc), [Thr2]SRTb, [Asn4]SRTb and [Glu9]SRTb, were synthesized chemically. From the comparisons of lethality, vasoconstrictor activity and receptor binding activity of SRTb, SRTa [( Asn13]SRTb), SRTc [( Thr2,Asn4,Glu9,Asn13]SRTb), [Thr2]SRTb, [Asn4]SRTb and [Glu9]SRTb, it appears that the Lys9 to Glu9 substitution greatly diminishes these activities while the Lys4 to Asn4 substitution does not affect them, and the Ser2 to Thr2 substitution or the Tyr13 to Asn13 substitution slightly diminishes these activities. These results suggest that the very low activities of SRTc are caused mainly by the Lys9 to Glu9 substitution, but not by the Ser2 to Thr2 substitution, which was suggested to be responsible for the weak bioactivities of SRTd [( Thr2,Ile19]SRTb).

Correlation between in vitro and in vivo models of proconvulsive activity with the carbapenem antibiotics, biapenem, imipenem/cilastatin and meropenem.

The present study evaluated the proconvulsant liability of biapenem, a novel carbapenem antibiotic, in in vitro and in vivo experiments, in comparison with the carbapenems, imipenem/cilastatin and meropenem. Imipenem/cilastatin is a carbapenem antibiotic with known proconvulsive liability in man and in animal experiments. In in vivo studies imipenem/cilastatin, at doses of 400/400 mg/kg i.v., significantly lowered the convulsive threshold of pentylenetetrazol (PTZ) in mice and shifted the dose-response curve of PTZ. The effects of biapenem (400 mg/kg i.v.) and another reference carbapenem, meropenem (400 mg/kg i.v.), in the mouse PTZ model were not significantly different from control. In in vitro experiments the carbapenems were tested for their ability to inhibit [3H]muscimol (1.3 mM) binding to rat brain homogenates at concentrations of 1-10 mM. Similar to in vivo results, when compared to imipenem/cilastatin, biapenem and meropenem did not inhibit [3H]muscimol binding to the GABAA receptor complex in brain homogenates while imipenem/cilastatin exhibited significant inhibition (IC50 = 4.6 mM). These results further confirm the correlation between in vitro GABAA binding and in vivo PTZ convulsive testing with carbapenem antibiotics, and suggest that biapenem possesses a low proconvulsive liability.

[Croton oil-induced hemorrhoid model in rat: comparison of anti-inflammatory activity of diflucortolone valerate with other glucocorticoids].

A hemorrhoid model was prepared by means of application of croton oil onto the recto-anus of rats. Cotton swab soaked with the inducer, which consisted of water, pyridine, diethylether and 6% croton oil in diethylether, was inserted into the anus. The following conditions were found to be optimal for preparing the model: cotton swab containing 0.16 ml of the inducer solution was applied to the anus of a 6 week-old rat (body wt. about 140 g) for 10 sec. The edema developed linearly until 7-8 hr after application, and the severity of the edema was sustained almost constantly for more than 24 hr. Macroscopic observations at 6 hr p. a. revealed homogeneous and consistent inflammation in the recto-anus applied region. Histological observation showed appearance of edema, infiltration of fibrin, inflammatory cells, vasodilation, blood congestion and medium to high degrees of necrosis in the mucosal epithelium. Thus this model was useful for evaluating the effect of anti-hemorrhoidal drugs on intumescence and vasodilatation. The efficacy of diflucortolone valerate, hydrocortisone caproate and hydrocortisone was evaluated in this model. Wet weight and vasopermeability increased by the inducer was suppressed strongly by simultaneous application of the corticoids, and the degree of suppression was parallel with the potency of the glucocorticoid activity. Compared to Scheriproct, Posterisan forte, Posterisan and Borraginol N, Neriproct showed the strongest effects in the protection against and treatment of the experimental hemorrhoid. Scheriproct, which was less active than Neriproct, was also found to have higher efficacy than the others.

Low neurotoxicity of LJC 10,627, a novel 1 beta-methyl carbapenem antibiotic: inhibition of gamma-aminobutyric acidA, benzodiazepine, and glycine receptor binding in relation to lack of central nervous system toxicity in rats.

The toxicity of LJC 10,627 to the central nervous system of rats was evaluated by examining the effects of the compound on gamma-aminobutyric acidA, benzodiazepine, and glycine receptor binding in rat synaptic membranes and on the induction of behavioral convulsions by intraventricular administration to rats. The concentrations of this compound needed to inhibit specific [3H]muscimol binding, specific [3H]diazepam binding, and specific [3H]strychnine binding were greater than those of imipenem, as demonstrated by the 50% inhibitory concentrations (IC50S of LJC 10,627, greater than 10 mM for each; IC50S of imipenem, 0.6, 1.9, and 0.2 mM, respectively). These results reflect the fact that LJC 10,627 does not evoke severe convulsions or cause death, even when it is administered intraventricularly at a high dose (300 micrograms per rat), and suggest that the low neurotoxic potential of LJC 10,627 may be attributed to the chemical structure of this compound, which has a methyl radical at the 1 beta site and a triazolium radical at the side chain of the second site.

Effect of Amytal on metabolism of perfused rat heart: relationship between glycolysis and oxidative phosphorylation.

In perfused rat hearts, infusion of increasing concentration of Amytal caused progressive inhibition of respiration and increase in glycolytic activity. At maximal inhibition of respiration, with glucose as the substrate, glycolysis provided about 60% of the total ATP produced. The myocardial content of ATP remained constant irrespective of the infused Amytal concentration but [CrP]/[Cr] and [ATP]/[ADP]f[Pi] progressively decreased. Changes in the concentrations of glycolytic intermediates were observed, the most pronounced of which were increases in fructose 1,6-diphosphate and lactate contents and a decrease in the pyruvate level. Myocardial levels of oxaloacetate, malate, and alanine were elevated and so was alanine release from the tissue. Substitution of glucose with pyruvate caused a large increase in the concentrations of the tricarboxylic acid cycle intermediates and consequent accumulation of reducing equivalents in the mitochrondria. With the latter substrate, in the presence of Amytal, the rates of mitochondrial ATP production were higher than those with glucose as the substrate. The metabolic picture of the Amytal block resembles biochemical manifestations of human myopathies of mitochondrial origin, and therefore Amytal inhibition is a convenient model system for exploration of intermediary metabolism in these defects.