Cross-species comparisons of the pharmacokinetics of ibudilast.

To enable clinical development of ibudilast for new indications, its pharmacokinetics were characterized in mice, rats, rabbits, dogs, cynomolgus monkeys, and minipigs. Animal pharmacokinetics were compared with a separate study in healthy volunteers. Following oral dosing, the dose-normalized area under the curve (AUC) (DN-AUC(24h)) in humans is 896 ((ng*h ml(-1))/(mg kg(-1))), and in animals ranges from 0.3 to 87. The variability among species cannot be explained by intrinsic clearance, which in intravenous dosing experiments shows only moderate interspecies variation (13-41 l h(-1) m(-2)). A portal vein rat pharmacokinetics model suggested that differences in first-pass gut clearance may explain some of the interspecies variation in oral bioavailability. Ibudilast shows auto-induction of metabolism in some animals, but not in humans. Plasma protein binding in humans and some animals is greater than or equal to 95%. The primary metabolite 6,7-dihyrdodiol-ibudilast is measurable and has been quantitated in plasma from animals and humans. Finally, biodistribution studies show that ibudilast distributes rapidly, extensively, and reversibly to the central nervous system.

A T-cell-selective interleukin 2 mutein exhibits potent antitumor activity and is well tolerated in vivo.

Human interleukin 2 (IL-2; Proleukin) is an approved therapeutic for advanced-stage metastatic cancer; however, its use is restricted because of severe systemic toxicity. Its function as a central mediator of T-cell activation may contribute to its efficacy for cancer therapy. However, activation of natural killer (NK) cells by therapeutically administered IL-2 may mediate toxicity. Here we have used targeted mutagenesis of human IL-2 to generate a mutein with approximately 3,000-fold in vitro selectivity for T cells over NK cells relative to wild-type IL-2. We compared the variant, termed BAY 50-4798, with human IL-2 (Proleukin) in a therapeutic dosing regimen in chimpanzees, and found that although the T-cell mobilization and activation properties of BAY 50-4798 were comparable to human IL-2, BAY 50-4798 was better tolerated in the chimpanzee. BAY 50-4798 was also shown to inhibit metastasis in a mouse tumor model. These results indicate that BAY 50-4798 may exhibit a greater therapeutic index than IL-2 in humans in the treatment of cancer and AIDS.

Phase I trial of subcutaneous recombinant macrophage colony-stimulating factor: clinical and immunomodulatory effects.

PURPOSE: Recombinant human macrophage colony-stimulating factor (rM-CSF) has been demonstrated to control the growth, differentiation, and function of mononuclear phagocytes. Preclinical studies have indicated antitumor effects, and therefore a phase I trial of rM-CSF in patients with malignancy was initiated. The toxicity and hematologic and immunologic effects were investigated. PATIENTS AND METHODS: rM-CSF was administered as a subcutaneous injection on days 1 through 5 and 8 through 12. Cycles were repeated every 28 days. Cohorts of four to seven patients received rM-CSF at dose levels from 0.1 to 25.6 mg/m2/d. Forty-two patients received 88 cycles of rM-CSF. All patients had metastatic solid tumors refractory to standard therapy. RESULTS: The toxicity of rM-CSF was mild. Dose-limiting toxicity included thrombocytopenia (two patients) and iritis (one patient) occurring at a dose of 25.6 mg/m2/d. Hematologic studies demonstrated dose-related monocytosis occurring routinely at doses > or = 3.2 mg/m2/d, and thrombocytopenia. Immunologic studies demonstrated enhanced secretion of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1-beta (IL-1 beta) by monocytes after in vitro stimulation with lipopolysaccharide, and increased expression of TNF-alpha mRNA at higher rM-CSF dose levels. Pharmacokinetic studies demonstrated that the systemic clearance rate of M-CSF increases during week 1 of therapy, resulting in lower blood levels of M-CSF during the second week of therapy. CONCLUSION: rM-CSF can be safely administered to patients, and has biologic activity on peripheral-blood monocytes.

Dressler's syndrome and angina pectoris relieved by surgery.

A 49-year-old woman with progressive angina pectoris developed chronic Dressler's syndrome following a second myocardial infarction. Control of the chronic pericarditis required long-term steroid therapy. Because of multiple complications generated by the steroid administration, she underwent coronary angiography followed by pericardiectomy and coronary artery bypass surgery. The patient remains asymptomatic without steroid or antianginal medication five years after surgery.

A comparison of synthetic absorbable suture with synthetic nonabsorbable suture for construction of tracheal anastomoses.

This study compares the use of synthetic absorbable suture (SAS, Vicryl) with that of synthetic nonabsorbable suture (SNS, Ticron) for construction of cervical tracheal anastomoses in the dog. Fourteen mongrel dogs underwent resection of one to four tracheal rings. Paired tracheal anastomoses were constructed, using 10 SAS or 10 SNS. After two months each anastomosis was removed and analyzed. All animals survived with intact anastomoses. There were no visible reactions to the SAS. Twenty-six of 70 SNS developed gross suture granulations. Significant stenosis developed in one of seven SAS and in four of seven SNS anastomoses. Histologic examination revealed no residual inflammatory reaction in the SAS specimens, while the SNS demonstrated a spectrum of inflammatory response that directly correlated in intensity with the gross appearance. These findings support the continued evaluation for the use of SAS in clinical tracheobronchoplastic procedures.

An analysis of direct and indirect measurements of left atrial filling pressure.

Left ventricular function may be assessed by direct catheter measurements of left atrial pressure or by indirect measurements of pulmonary artery wedge pressure or pulmonary artery end-diastolic pressure. Controversy exists as to how closely the indirect measurements correlate with true left atrial pressure and to which is the most accurate. To clarify this probelm, we studied 43 patients undergoing cardiac surgical procedures with cardiopulmonary bypass. Both left atrial catheters for direct measurement and Swan-Ganz catheters were placed at the time of surgery. All patients were monitored continuously for 48 hours and hourly measurements were recorded. The resultant 1,620 left atrial pressure and pulmonary artery wedge pressure figures and 1,860 left atrial pressure and pulmonary artery end-diastolic wedge pressure measurements were subjected to computer analysis. The following conclusions have been found: (1) Pulmonary artery wedge pressure is a better indirect measure of left atrial pressure than is pulmonary artery end-diastolic wedge pressure (pooled correlation coefficient 0.629); (2) direct left atrial pressure measurement is more reliable and has fewer complications than indirect measurements; (3) there is no consistent correlation between left atrial pressure and central venous pressure (pooled correlation coefficient 0.3). A discussion of our results and the problems associated with left atrial catheters and Swan-Ganz catheters is presented.

Benzo[e]pyrene elicits changes in the biochemical activities and chromatographic behavior of murine hepatic cytochromes P-450 that are distinct from those induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin.

The objective of this study was to examine the potential for a specific ligand of carcinogen binding protein (CBP) to induce changes in the overall character of hepatic microsomal cytochromes P-450 (P450) and to compare potential changes with those induced by an Ah receptor ligand. Benzo[e]pyrene (BeP) was previously shown to bind CBP with high affinity and Ah receptor with low affinity. In contrast, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) binds Ah receptor avidly and CBP weakly. Hepatic microsomes were prepared from C57BL/6J (B6) and DBA/2J (D2) mice treated with corn oil, BeP or TCDD. Relative to corn oil controls, pretreatment of B6 mice with BeP or TCDD increased the nmol P450/mg microsomal protein content 26 and 28%, respectively. In D2 mice, nmol P450/mg microsomal protein was increased 23% in the BeP pretreatment, while TCDD pretreatment had no effect relative to the corn oil controls. For the O-alkyl ethers of resorufin, rates of metabolism (per nmol P450) were affected differently in B6 and D2 by BeP pretreatment. Pentoxyresorufin O-dealkylase activity was reduced to 44% of control activity in B6 mice and increased 39% relative to controls in D2 mice. BeP pretreatment had no effect on ethoxyresorufin O-dealkylase activity in B6 mice, while this activity was decreased to 58% of controls in D2 mice. Additionally, benzyloxyresorufin O-dealkylase activity was reduced to 65% of control levels in B6 mice and not affected in D2 mice. Methoxyresorufin O-dealkylase activity was reduced in both strains to an average of 55% of control values. As expected, TCDD pretreatment resulted in increases of all O-dealkylations measured in both strains of mouse. For both inbred strains of mouse, anion exchange chromatography revealed a P450 peak associated with BeP pretreatment that was not present in chromatograms generated with corn oil or TCDD pretreatments. Results of enzyme linked immunosorbant assays also indicated that the pattern of P450 isoenzyme expression associated with BeP pretreatment was distinct from that associated with TCDD pretreatment. Overall, these data show that treatment with a specific ligand of CBP induces changes the biochemical activities and chromatographic behavior of P450 isozymes in murine hepatic microsomes. Moreover, they indicate that changes in P450 occurring after treatment with a CBP ligand are distinct from those changes that are associated with treatment with an Ah receptor ligand (TCDD). Differences between B6 and D2 strains suggest that the hepatic P450 changes occurring in response to pretreatment with a CBP ligand may be influenced by the presence of Ah receptor.

Benzo[e]pyrene pretreatment of immature, female C57BL/6J mice results in increased bioactivation of aflatoxin B1 in vitro.

Hepatic microsomes were prepared from immature C57BL/6J mice 24 h after receiving intraperitoneal injections of either corn oil, benzo[e]pyrene (BeP, 50 mg/kg) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 4 x 10(-3) mg/kg). The capacity of these hepatic microsomes to bioactivate aflatoxin B1 (AFB1), 2-aminoanthracene (AA), benzo[a]pyrene (BaP), 3-methylcholanthrene (MC), 7,12-dimethylbenzanthracene (DMBA), BeP and pyrene (PY) was measured using strain TA100 in the Salmonella typhimurium/microsome reversion assay. BeP pretreatment of mice resulted in a 33% increase in mutagenic potency (MP) of AFB1 over the corn oil controls and a 70% increase in MP relative to TCDD-pretreated microsomes. With AA, BaP and DMBA as promutagens, BeP pretreatment reduced MP an average of 24%, while TCDD pretreatment increased MP of these 3 promutagens 263% compared to controls. Since the general effects of BeP and TCDD on murine hepatic cytochrome P-450 (P450)-mediated activities in this study were discordant, it appears that changes in P450 activity by BeP pretreatment are not mediated through the Ah receptor.

Enhanced cell-associated plasminogen activator pathway but not coagulation pathway activity contributes to motility in metastatic breast cancer cells.

BACKGROUND: Activation of tumor cell-associated coagulation and plasminogen activator pathways occurs in malignant disease processes, including breast cancer, and may promote metastatic activity. OBJECTIVES/METHODS: To compare the coagulation and plasminogen activator pathways of normal and metastatic cells, we examined two cell lines from the MCF-10 family of breast cells: near-normal immortalized MCF-10A cells, and metastatic MCF-10CA1 cells. RESULTS: MCF-10CA1 cell motility was significantly increased as compared with that of MCF-10A cells. The two cell types supported similar rates of factor Xa generation, plasma thrombin generation, and fibrin formation. MCF-10A cells produced a stable fibrin network, whereas MCF-10CA1 cells lysed the surrounding fibrin network within 24 h of network formation. Importantly, fibrin located proximal to (within 10 microm) the MCF-10CA1 cell surface lysed substantially faster than fibrin located 100 microm from the surface. MCF-10CA1 cells supported significantly increased plasmin generation rates as compared with MCF-10A cells, providing a mechanism for the increased fibrinolytic activity of these cells towards the fibrin network. Metastatic MCF-10CA1 cells had increased expression (mRNA and protein) levels of urokinase plasminogen activator (u-PA) and decreased levels of plasminogen activator inhibitor-1 as compared with MCF-10A cells. Blocking u-PA activity with the active site-directed protease inhibitor amiloride substantially decreased MCF-10CA1 cell motility. Phosphorylated Akt levels were elevated in MCF-10CA1 cells, which partially explains the increased u-PA expression. CONCLUSIONS: These results suggest that the tumor-associated plasminogen activator pathway, not the coagulation pathway, is a key distinguishing feature between metastatic MCF10-CA1 cells and normal MCF-10A cells.

Halothane and isoflurane only slightly impair arterial oxygenation during one-lung ventilation in patients undergoing thoracotomy.

Controversy exists as to whether the halogenated inhalation (IH) anesthetics impair arterial oxygenation during one-lung ventilation (1-LV). Accordingly, the authors have answered this question in 12 consenting patients who required 1-LV to facilitate the performance of thoracic surgery, by comparing arterial oxygenation during a prolonged period of IH anesthesia with arterial oxygenation during a prolonged period of intravenous (IV) anesthesia during stable 1-LV conditions. The patients were equally divided into halothane and isoflurane groups. Each patient in each IH anesthetic group underwent the following experimental sequence: step 1, two-lung ventilation (2-LV), 1 MAC IH anesthesia; step 2, 1-LV, 1 MAC IH anesthesia; step 3, 1-LV, iv anesthesia; step 4, 2-LV, iv anesthesia. Stable 1-LV conditions were proven by serial arterial blood gas measurement. Conversion from 2-LV to 1-LV during IH anesthesia (step 1 to step 2) caused a very large and significant decrease in PaO2 (from 484 +/- 49 to 116 +/- 61, and from 442 +/- 58 to 232 +/- 97 mmHg in the halothane and isoflurane groups, respectively) and increase in shunt (from 14 +/- 4 to 44 +/- 9, and from 19 +/- 5 to 31 +/- 8% in the halothane and isoflurane groups, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Intestinal absorption screening of mixtures from combinatorial libraries in the Caco-2 model.

PURPOSE: Understanding how chemical structures influence transport across the intestinal mucosa will greatly enhance the discovery of orally available drugs. In an attempt to accelerate defining such relationships between structure and transport, six arbitrary mixtures of N-substituted glycine (NSG) peptoids containing 24 physicochemically diverse compounds were evaluated in the Caco-2 model of intestinal absorption. METHODS: Samples were analyzed by HPLC and the areas of the peaks representing the components of each mixture were summed to measure "aggregate" apparent permeability coefficients (Papp), a score of the influence of the common structural element within each mixture towards absorption. Mass spectrometry was used to identify the chemical structure of Caco-2 permeable compounds. RESULTS: Three linear trimeric mixtures were examined and, for each mixture, none of the components was detected in receiver chambers. It was concluded that the components of these mixtures each had a Papp value less than 0.8 x 10(-6) cm/sec, a permeability less than mannitol. Three dimeric mixtures were examined and they exhibited aggregate P(app) values of 9.2 x 10(-6), 14 x 10(-6) and 6.9 x 10(-6) cm/sec. These transport rates reflected the transport of most of the components of each mixture. Furthermore, the components of the dimeric mixtures which were transported at a rate greater than mannitol were apparently transported by passive mechanisms. CONCLUSIONS: This study demonstrated that mixtures can be used to study structure-transport relationships in the Caco-2 model. The information obtained from this type of study will be integrated into the design of future chemical libraries. Other potential uses of chemical mixtures with the Caco-2 model are also discussed.

The recessed chest wall pacemaker pocket.

Recurrent pouch problems led to the development of a recessed chest wall pacemaker pocket. Segments of the seventh and eighth ribs were resected in the mid-axillary line resulting in a "tailor-made" space suitable for generator implantation. Follow-up at one year has proven the chest wall to be a satisfactory alternative site for a pacemaker pocket.

Quantitation of the renal clearance of interleukin-2 using nephrectomized and ureter-ligated rats.

The objective of this work was to determine the role of the kidneys in the systemic clearance rate (CL) of interleukin-2 (IL-2). Rats received IL-2 by i.v. bolus and the pharmacokinetic data were found to be well described by a two-compartment, first-order elimination model. With administration of 0.2, 0.5 or 1.0 mg/kg of IL-2 (n = 3 per treatment), the median alpha and beta half-lives (T1/2 alpha, 2.3 min; T1/2 beta, 13.2 min, respectively), initial volume of distribution (V1, 93 ml/kg), volume of distribution at steady state (Vss, 198 ml/kg) and CL (16.8 ml min-1 kg-1) did not vary with the dose (P = .05). This demonstration of first-order kinetics suggested that renal CL remains constant over a range of doses. The pharmacokinetic properties of 1.0 mg/kg of IL-2 were examined after either single or double nephrectomy (n = 3 and 4, respectively), sham operation (n = 4) or no renal operation (n = 4; the "controls"). No difference in median T1/2 alpha, T1/2 beta, V1, Vss or CL was detected between control and sham-operated rats nor between single nephrectomy and sham operation. Compared with sham operation, double nephrectomy showed no significant change in V1 or Vss but the T1/2 alpha and T1/2 beta approximately doubled and CL was reduced by 75%. In a separate experiment, ureter-ligated rats were compared with sham-operated rats. With ureter ligation, T1/2 alpha, T1/2 beta, V1 and Vss were unchanged but CL was reduced by 36%.