Gemcitabine (G) plamsa and intracellular pharmacokinetics in E6201: Greater metabolite levels using fixed dosing rate (FDR) delivery

2024

Background: Gemcitabine (G) is an antimetabolite which requires activation by the rate-limiting enzyme dCK to its active metabolite, dFdCTP. FDR delivery of G at 10 mg/m2/minute may allow greater formation of active metabolite and improved activity. E6201 randomly assigned first line pancreatic cancer patients to three arms: A (G 1000 mg/m2 over 30 minutes), B FDR G (1500 mg/m2 over 150 minutes), and C GemOx (1000 mg/m2 over 100 minutes with oxaliplatin 100 mg/m2). Methods: Investigators from 18 centers contributed 23 sample sets on the first dose of G. Five time points over 4 hrs were sampled (baseline, mid infusion, end infusion, 1–2 post and 4 hrs). Plasma fractionation along with the PBMC purification and subsequent perchloric acid extraction were conducted locally with THU 1 mg (cytidine deaminase inhibitor). Samples were shipped overnight to the central lab where G and its metabolite dFdU were quantified from deproteinized plasma by reverse phase HPLC. dFdCTP was quantified by ion-exchange HPLC in neutralized PBMC extracts after removal of ribonucleotide triphosphates. Data were fit to nonlinear models (WinNonLin, v4.1) and comparisons amongst dosing groups employed the non-parametric, 2-sided Mann-Whitney test. Results: For Arms A, B and C the plasma AUCs were respectively (median ± SD): 4542 ± 2472 (N=9), 8603 ± 2608 (N=8) and 9130 ± 8788 (N=6) ng/ml x hr. The difference between group A and B (p=0.003) and A and C (p=0.05) were statistically different. Intracellular dFdCTP AUCs for groups A, B, and C were: 1862 ± 794 (N=8); 3725 ± 7763 (N=8) and 5024 ± 2113 (N=5) and significantly different for both A vs. B (p=0.05) and borderline significant for A vs C (p=0.065). The latter comparison is limited by a small number of samples. Conclusions: When studied in a multi-centered, randomized cooperative group setting, FDR delivery of G results in higher plasma AUC, and increased intracellular levels of active metabolite dFdCTP. These data support the concept that fixed dose rate delivery of G results in greater intracellular metabolite production at similar and equitoxic doses. Supported by ECOG NYU620HH04–00, NCI CA16087, CA2115, and from Eli Lilly.

No significant financial relationships to disclose.

Continuous intravenous infusion (CIVI) topotecan may be safely combined with tipifarnib

2064

Background: Dose limiting (DL) myelosuppression occurred when topotecan 1.0 mg/m2/d × 5d was combined with tipifarnib (Proc ASCO, 2001, abst 321). We now report on a 3+3 cohort design to determine the safety and pharmacokinetics (PK) of this combination with topotecan given as CIVI in patients (pts) with refractory solid tumors. Methods: Pts were treated with escalating dose levels of topotecan (0.2–0.4 mg/m2/d) given as 21-day infusion in combination with tipifarnib 200 mg PO bid for 21 d every 28 d. Blood was drawn for topotecan PK and intracellular (PBMC) toposisomerase I on d 1 (baseline) and d 5 (tipifarnib omitted d1, cycle 1), and weekly × 8 for ras-farnesylation (membrane bound fraction). Plasma levels of the closed form of topotecan were determined by SPE and HPLC with fluorometric detection. Topoisomerase I in PBMCs was detected by Western blot. Results: 14 patients were accrued at 3 dose levels: topotecan 0.2 mg/m2/d (3 pts), 0.3 mg/m2/d (3), and 0.4 mg/m2/d (8), combined with tipifarnib. Median age was 50 years (33–62). 32 cycles (median 2) were given. Grade 1–3 fatigue, nausea, thrombocytopenia, neutropenia and anemia were common, and at dose level 3, two heavily-pretreated patients had DL myelosuppression. Six others had no significant toxicity over prolonged times. Of nine evaluable for response, a mucinous peritoneal cancer had a minor response for 5 m, an ovarian granulosa cell tumor had a mixed response in lung metastases for 15 m, and a PNET of bone had a minor response for 17 m; six had progression. Mean steady state (± SD) levels of topotecan for dose levels I, II and III were, respectively, 0.48 ± 08 (N = 3), 1.26 ± 0.32 (N = 3) and 1.47 ± 0.1 (N = 5) ng/ml, and were linear with respect to topotecan dose (r = 0.95). By the end of the 21 d infusion, 90% of baseline topoisomerase I signal was depleted in PBMCs. Conclusions: In contrast with bolus topotecan, CIVI topotecan may be combined at known effective doses with tipifarnib. Recommended phase II doses are 0.4 mg/m2/d × 21 days and 200 mg bid daily for those with limited prior therapy. Phase II studies in gynecologic and breast tumors are planned. Supported by UO1- 76642; CA 16087.

[Table: see text]

Global patterns in availability of emergency obstetric care

OBJECTIVE

This paper examines the availability of basic and comprehensive emergency obstetric care (EmOC), interventions used to treat direct obstetric complications. Determining what interventions are provided in health facilities is the first priority in analyzing a country's capabilities to treat obstetric emergencies. There are eight key interventions, six constitute basic EmOC and all eight comprehensive EmOC.

METHODS AND RESULTS

Based on data from 24 needs assessments, the following global patterns emerge: comprehensive EmOC facilities are usually available to meet the recommended minimum number for the size of the population, basic EmOC facilities are consistently not available in sufficient numbers, both in countries with high and moderate levels of maternal mortality, and the majority of facilities offering maternity services provide only some interventions indicating an unrealized potential.

CONCLUSION

Upgrading maternities, health centers and hospitals to at least basic EmOC status would be a major contributing step towards maternal mortality reduction in resource-poor countries.

Measuring progress towards the MDG for maternal health: Including a measure of the health system's capacity to treat obstetric complications

OBJECTIVE

This paper argues for an additional indicator for measuring progress of the Millennium Development Goal for maternal health-the availability of emergency obstetric care.

METHODS

MDG monitoring will be based on two indicators: the maternal mortality ratio and the proportion of births attended by skilled personnel. Strengths and weaknesses of a third indicator are discussed

RESULTS

The availability of EmOC measures the capacity of the health system to respond to direct obstetric complications. Benefits to using this additional indicator are its usefulness in determining an adequate distribution of services and showing management at all levels what life-saving interventions are not being provided, and stimulate thought as to why. It can reflect programmatic changes over a relatively short period of time and data requirements are not onerous.

CONCLUSION

A measure of strength of the health system is important since many interventions depend on the health system for their implementation.

The availability of life-saving obstetric services in developing countries: an in-depth look at the signal functions for emergency obstetric care

OBJECTIVE

This paper examines the frequency with which a set of life-saving interventions or signal functions was performed to treat major obstetric complications.

METHODS AND RESULTS

The basic signal functions include parenteral antibiotics, anticonvulsants and oxytocics, and the procedures of manual removal of the placenta, removal of retained uterine products, and assisted vaginal delivery. Comprehensive functions include the six basic functions, cesarean delivery, and blood transfusions. Data from 1906 health facilities in 13 countries indicate that the most likely functions to be reported are oxytocics and antibiotics. The basic function least likely to be reported is assisted vaginal delivery. Many of the facilities surveyed did not have the infrastructure to perform operations or provide blood transfusions.

CONCLUSIONS

These data can help governments allocate their budgets appropriately, help policy makers and planners identify systemic bottlenecks and prioritize solutions. Monitoring the performance of the functions informs us of the capacity of the health system to provide key interventions when obstetric emergencies occur.

Rheo-optical studies of carbon nanotube suspensions

We use a polarization-modulation technique to investigate the optical anisotropy of multi- and single-wall carbon nanotubes suspended in a variety of solvents under simple shear flow. Measurements of birefringence and dichroism are performed as a function of shear rate, tube concentration, and solvent viscosity. At fixed volume fraction, the anisotropy increases with increasing shear stress due to enhanced flow alignment. At fixed shear stress, the anisotropy increases with volume fraction due to rotational excluded-volume interactions. By considering the rotational diffusivity as a function of nanotube length, diameter, concentration, and solvent viscosity, we demonstrate a leading-order scaling relation for the optical anisotropy in terms of rotary Peclet number Pe. At low Pe, our results are in qualitative agreement with the theoretical predictions of Doi and Edwards. At high Pe, our data suggest that the degree of nanotube alignment scales as Pe16.

Anisotropy of sheared carbon-nanotube suspensions

We measure the anisotropy of sheared carbon-nanotube suspensions for a broad range of concentration, aspect ratio, and strain rate using a variety of methods. Our measurements highlight the importance of excluded-volume interactions in the semidilute regime, with scaling in terms of a dimensionless shear rate. Our results also suggest that such interactions might be exploited to fractionate carbon nanotubes by length in simple shear flow.

The evidence for emergency obstetric care

PURPOSE

We searched for evidence for the effectiveness of emergency obstetric care (EmOC) interventions in reducing maternal mortality primarily in developing countries.

METHODS

We reviewed population-based studies with maternal mortality as the outcome variable and ranked them according to the system for ranking the quality of evidence and strength of recommendations developed by the US Preventive Services Task Force. A systematic search of published literature was conducted for this review, including searches of Medline, PubMed, Cochrane Database of Systematic Reviews, the Cochrane Pregnancy and Childbirth Database and the Cochrane Controlled Trials Register.

RESULTS

The strength of the evidence is high in several studies with a design that places them in the second and third tier in the quality of evidence ranking system. No studies were found that are experimental in design that would give them a top ranking, due to the measurement challenges associated with maternal mortality, although many of the specific individual clinical interventions that comprise EmOC have been evaluated through experimental design. There is strong evidence based on studies, using quasi-experimental, observational and ecological designs, to support the contention that EmOC must be a critical component of any program to reduce maternal mortality.

Program note: applying the UN Process indicators for emergency obstetric care to the United States

The United Nations Process Indicators for emergency obstetric care (EmOC) have been used extensively in countries with high maternal mortality ratios (MMR) to assess the availability, utilization and quality of EmOC services. To compare the situation in high MMR countries to that of a low MMR country, data from the United States were used to determine EmOC service availability, utilization and quality. As was expected, the United States was found to have an adequate amount of good-quality EmOC services that are used by the majority of women with life-threatening obstetric complications.

Cluster shape anisotropy in irreversibly aggregating particulate systems

The results for cluster shape anisotropy over a broad range (10)(-3)-10(-1)) of monomer volume fractions, fv values, are presented for both two- (2d) and three-dimensional (3d) simulations of diffusion-limited (DLCA), ballistic-limited (BLCA), and reaction-limited (RLCA) cluster-cluster aggregation classes. We find that all three aggregation classes have different dilute-limit shape anisotropies, with the diffusion-limited model having the largest value of anisotropy and the reaction-limited model having the smallest. The simulation result for the cluster shape anisotropy for each of the three aggregation classes is slightly less than the corresponding prediction of the hierarchial model. In addition, we find excellent agreement between the 2d DLCA simulation results and experimental measurements of shape anisotropy. At late times, shape anisotropy decreases from the dilute-limit value.

A phase I study of AMD473 and docetaxel given once every 3 weeks in patients with advanced refractory cancer: a National Cancer Institute of Canada-Clinical Trials Group trial, IND 131

BACKGROUND

AMD473 (previously ZD0473) is a new-generation platinum compound with activity against a wide range of human tumour cell lines and xenografts, including carboplatin- and cisplatin-resistant lines. To assess its potential combined with a taxane, a phase I study of AMD473 and docetaxel in advanced cancer was initiated by the National Cancer Institute of Canada-Clinical Trials Group.

PATIENTS AND METHODS

Patients with advanced cancer, measurable disease, performance status Eastern Cooperative Oncology Group 0-2, no major organ dysfunction, and one or no previous taxane regimen received escalating doses of AMD473 and docetaxel every 3 weeks, with a starting dose of AMD473 80 mg/m(2) and docetaxel 60 mg/m(2).

RESULTS

Thirty-three patients enrolled on four dose levels were evaluable for toxicity and 25 patients were evaluable for response. The maximum tolerated dose was dose level 4 (AMD473 120 mg/m(2) and docetaxel 75 mg/m(2)), with grade 4 neutropenia in both minimally and heavily pretreated patients causing dose-limiting toxicity. As well at dose level 4, one patient had grade 3 vomiting despite premedication. Dose level three was expanded for both groups of patients and was defined as the recommended phase II dose at AMD473 100 mg/m(2) and docetaxel 75 mg/m(2). Non-hematologic toxicities included fatigue, diarrhoea and other mild toxicities. There was one partial response in a patient with prostate cancer and stable disease in 15 patients. No apparent pharmacokinetic interaction was noted.

CONCLUSION

AMD473 and docetaxel can be combined with a recommended phase II dose level of 100 mg/m(2) and 75 mg/m(2), respectively, given intravenously every 3 weeks. The combination has activity and should be explored in responsive tumour types.

Structural crossover in dense irreversibly aggregating particulate systems

Cluster-cluster aggregation has been simulated by off-lattice Monte Carlo methods for diffusion-limited (DLCA), ballistic-limited, and reaction-limited cluster aggregation classes. We find that as the system evolves and becomes dense, the largest cluster develops a hybrid structure with mass fractal dimension D(f) approximately 2.6 over large length scales, while at smaller length scales, the early time dilute-limit fractal structure is frozen in. The largest cluster is thus an aggregate of smaller aggregates with a different fractal dimension, and we call it a "superaggregate." The crossover length separating the two morphologies, which we call the critical radius of gyration, can be calculated based on a simple theory that assumes a monodisperse cluster size distribution. This agrees well with simulation results for DLCA. However, for other classes we find that the increasing polydispersity in cluster size pushes the simulated crossover length radius of gyration to values systematically larger than the predicted value.

Computer simulation of selective aggregation in binary colloids

The morphology of clusters formed by selective aggregation of binary colloids is studied in a two-dimensional Monte Carlo simulation for a large range of number fractions (200:1, 100:1, 10:1, 2:1). We find remarkable similarity in morphology to those observed in experiments, from the formation of closed "micelles" to large branched clusters. Quantitative studies of the fractal dimension, kinetics, and cluster size distribution are also carried out and compared with diffusion-limited cluster aggregation and reaction-limited cluster aggregation models.

Molecular dynamics simulation of the transition from dispersed to solid phase

Molecular dynamics simulations in two dimensions of particles interacting with finite potentials comparable to k(B)T yield aggregates which cross over from a fractal to a compact crystalline morphology. Growth kinetics and aggregate size distributions evolve from nonequilibrium to equilibrium limits.

Enhanced kinetics and free-volume universality in dense aggregating systems

Aggregation kinetics and cluster-size distributions are studied with off-lattice, diffusion-limited cluster-cluster simulations. With increased cluster crowding (occurring at late times) as measured by the normalized free volume, Omega, both the kinetics speeds up and the size distribution broadens. The exponents characterizing each, z and lambda, respectively, are found to be universal functions of Omega. Moreover, the relation z=(1-lambda)(-1) continues to hold up to omega=0 (the ideal gel point), implying mean-field kinetics still applies despite the crowding.

Randomized, placebo-controlled trial of dietary supplementation of alpha-tocopherol on mutagen sensitivity levels in melanoma patients: a pilot trial

We evaluated the effects of vitamin E (dl-alpha-tocopherol) on mutagen sensitivity levels in a randomized placebo-controlled pilot trial. In brief, a dietary supplement of 1000 mg/day vitamin E or a placebo was randomly administered for 3 months to melanoma outpatients clinically free of the disease. Plasma vitamin E and mutagen sensitivity levels were measured at baseline and at the end of the trial after 3 months. At baseline, we found no significant differences in plasma vitamin E and mutagen sensitivity levels between the two groups. We also measured dietary intake at baseline and found dietary vitamin E to be a poor predictor of plasma levels of vitamin E. After 3 months of supplementation, we found that plasma levels of alpha-tocopherol increased significantly (P = 0.0005) in the vitamin E compared to the placebo group. We also found a non-significant, but consistent decrease in plasma gamma-tocopherol concentrations in the vitamin E supplemented compared to the placebo group. We did not find any significant difference between the vitamin E and placebo groups in mutagen sensitivity levels either at baseline or after 3 months of supplementation. We conclude that short term vitamin E supplementation, although it causes increased blood levels of alpha-tocopherol, does not provide protection against bleomycin-induced chromosome damage.

Unexpected x-ray emission due to formation of bound doubly excited states

A strong emission of characteristic M x rays is observed, without an M vacancy initially present, when slow highly charged ions (Ta(q+), q = 39--48) capture a single electron in single collisions with rare gas atoms (He). This is explained by the formation of bound doubly excited states through electron correlation. An elaborate theoretical treatment shows that bound doubly excited states are mixed with states where a Rydberg electron is bound in the core of a highly charged ion. It is striking that this occurs with a large probability (close to unity), and one needs to assume that higher Rydberg states are populated than predicted by the overbarrier model in order to explain the experimental results.

Pyrido[2,3-d]pyrimidin-7-one inhibitors of cyclin-dependent kinases

The identification of 8-ethyl-2-phenylamino-8H-pyrido[2, 3-d]pyrimidin-7-one (1) as an inhibitor of Cdk4 led to the initiation of a program to evaluate related pyrido[2, 3-d]pyrimidin-7-ones for inhibition of cyclin-dependent kinases (Cdks). Analysis of more than 60 analogues has identified some clear SAR trends that may be exploited in the design of more potent Cdk inhibitors. The most potent Cdk4 inhibitors reported in this study inhibit Cdk4 with IC(50) = 0.004 microM ([ATP] = 25 microM). X-ray crystallographic analysis of representative compounds bound to the related kinase, Cdk2, reveals that they occupy the ATP binding site. Modest selectivity between Cdks is exhibited by some compounds, and Cdk4-selective inhibitors block pRb(+) cells in the G(1)-phase of the cell division cycle.

The design and synthesis of potent cyclic peptide VCAM-VLA-4 antagonists incorporating an achiral Asp-Pro mimetic

The Asp-Pro sequence of the cyclic peptide Ac-HN-Tyr-Cys*-Asp-Pro-Cys*-OH (1) could be replaced with the achiral dipeptide mimetic 1-(2-aminoethyl)cyclpentylcarboxylic acid with retention of potent inhibition of the VCAM-VLA-4 interaction.

Hormonal regulation of the osteoblastic phenotype expression in neonatal murine calvarial cells

Osteoblastic cell cultures from fetal rat calvariae have provided a popular model for studying the effects of dexamethasone (DEX) and 1, 25 dihydroxyvitamin D3 [1,25(OH)2D3] on gene expression but data from murine calvarial cells are scarce. Species-specific responses of rat and mouse osteoblastic cells to these hormones have been reported previously. In the present study, we investigated the effects of DEX and 1,25(OH)2D3 on expression of the osteoblastic phenotype by mouse calvarial cells. These murine osteoblast-like (MOB) cells expressed alkaline phosphatase (ALP) activity and osteocalcin and formed calcified nodules. Unlike the rat calvarial cells, ALP activities and nodule formation in MOB were inhibited by DEX. 1,25(OH)2D3 enhanced and DEX lowered the amount of osteocalcin synthesized by MOB. 1,25(OH)2D3 did not affect the number of nodules, but increased their sizes. Treating the cells for 2 days with only DEX at the beginning of the culture enhanced the effect of 1, 25(OH)2D3 on ALP. We found that in murine calvarial cells, DEX inhibits and 1,25(OH)2D3 enhances ALP activity, osteocalcin synthesis, and calcified nodule formation. This is in contrast to previous reports of rat calvarial cells where DEX is a positive and 1,25(OH)2D3 can be a negative regulator of the osteoblastic phenotype. These results suggest that profound species-specific differences exist between mice and rats in the regulation of the osteoblastic phenotype.

Phase I trial of escalating doses of paclitaxel plus doxorubicin and dexrazoxane in patients with advanced breast cancer

PURPOSE

To determine the maximum-tolerable dose (MTD) of paclitaxel given as a 3-hour intravenous (IV) infusion that could be used in conjunction with doxorubicin and dexrazoxane, and to determine the effect of dexrazoxane on the pharmacokinetics of paclitaxel and doxorubicin.

PATIENTS AND METHODS

Twenty-five patients with advanced breast cancer received dexrazoxane (600 mg/m2 by IV infusion over 15 minutes), followed 15 minutes later by doxorubicin (60 mg/m2 IV), followed 15 minutes later by paclitaxel (150 or 175 mg/m2 by IV infusion over 3 hours) in cohorts of three to six patients using a standard phase I design without (group A) and with (group B) granulocyte colony-stimulating factor (G-CSF). Treatment continued until there was a substantial decrease in the left ventricular ejection fraction (LVEF), congestive heart failure, progressive disease, or physician discretion to discontinue.

RESULTS

The MTD of paclitaxel was 150 mg/m2, and adjunctive therapy with G-CSF was required to prevent febrile neutropenia. Dexrazoxane had no significant effect on the pharmacokinetics of paclitaxel or doxorubicin. After a median cumulative doxorubicin dose of 360 mg/m2 (range, 60 to 870 mg/m2), no patient developed congestive heart failure or had a decrease in LVEF below normal. An objective response occurred in all five patients with locally advanced breast cancer and in eight of 20 patients (40%; 95% confidence interval, 19% to 61%) with metastatic breast cancer.

CONCLUSION

When combined with doxorubicin (60 mg/m2) and dexrazoxane (600 mg/m2), paclitaxel given as a 3-hour infusion had an MTD of 150 mg/m2, and G-CSF was required to prevent febrile neutropenia. Dexrazoxane had no effect on the pharmacokinetics of paclitaxel or doxorubicin. No patient in this trial had a decrease in the LVEF below normal, compared with about 20% to 50% of patients treated with doxorubicin and paclitaxel without dexrazoxane in other trials.

Serum cytosolic beta-glucosidase elevation and early ischemic injury to guinea pig small intestine

BACKGROUND

The lack of an early, sensitive marker for intestinal ischemia has led to delay in diagnosis and worsended outcome for patients with acute onset of this condition. Our preliminary studies revealed that guinea pig cytosolic beta-glucosidase (CBG) is expressed predominantly in the small intestine, with lower levels in the liver and pancreas and undetectable levels in other organs. Cytosolic beta-glucosidase was investigated as a serum marker of small intestinal ischemia in a guinea pig model.

METHODS

Guinea pigs underwent anesthesia, sham laparotomy, 30 minutes of mesenteric ischemia followed by 6 hours of reperfusion 6 hours of sustained mesenteric ischemia, or closed-loop small bowel obstruction. Serum samples were assayed for CBG activity. At the conclusion of the ischemia/reperfusion experiments, small bowel samples were assayed for residual enzyme activity, and paraffin sections were graded for the severity of histologic injury.

RESULTS

Serum CBG activity rose rapidly after intestinal ischemia with and without reperfusion. Peak enzyme activities were elevated 23-fold for reperfused animals (P < .001) by 4 hours. For nonreperfused animals, peak serum CBG activities reached 29-fold above baseline and were significantly higher than the CBG activities of reperfused animals at 4 hours (P < .01) and at 6 hours (P < .05). Mucosal injury ranged from undetectable to moderate and corresponded in severity with both peak serum enzyme activity and decreased residual activity in the small bowel. In animals subjected to closed-loop obstruction, there was a mean increase of serum CBG of 9.2-fold from 4 to 6 hours after establishment of obstruction (P < .05).

CONCLUSIONS

In the guinea pig model, CBG is a sensitive marker of ischemic injury caused by arterial occlusion or closed-loop obstruction of the small bowel.

Dissociation of FAK/p130(CAS)/c-Src complex during mitosis: role of mitosis-specific serine phosphorylation of FAK

At mitosis, focal adhesions disassemble and the signal transduction from focal adhesions is inactivated. We have found that components of focal adhesions including focal adhesion kinase (FAK), paxillin, and p130(CAS) (CAS) are serine/threonine phosphorylated during mitosis when all three proteins are tyrosine dephosphorylated. Mitosis-specific phosphorylation continues past cytokinesis and is reversed during post-mitotic cell spreading. We have found two significant alterations in FAK-mediated signal transduction during mitosis. First, the association of FAK with CAS or c-Src is greatly inhibited, with levels decreasing to 16 and 13% of the interphase levels, respectively. Second, mitotic FAK shows decreased binding to a peptide mimicking the cytoplasmic domain of beta-integrin when compared with FAK of interphase cells. Mitosis-specific phosphorylation is responsible for the disruption of FAK/CAS binding because dephosphorylation of mitotic FAK in vitro by protein serine/threonine phosphatase 1 restores the ability of FAK to associate with CAS, though not with c-Src. These results suggest that mitosis-specific modification of FAK uncouples signal transduction pathways involving integrin, CAS, and c-Src, and may maintain FAK in an inactive state until post-mitotic spreading.

Pharmacodynamics of topoisomerase I inhibition: Western blot determination of topoisomerase I and cleavable complex in patients with upper gastrointestinal malignancies treated with topotecan

Analogues of camptothecins are specific inhibitors of eukaryotic DNA topoisomerase I (topo I) that lead to DNA damage and, eventually, cellular cytotoxicity. Camptothecin analogues bind to this target enzyme in the course of its normal function and stabilize the DNA-enzyme adduct to form a "cleavable complex." Preclinical experiments using Western blot analyses have shown cleavable complex formation to be the key intermediate step in topo I inhibition. In this series of experiments, it was our goal to convert this laboratory technique into a useful clinical assay, allowing measurement of the target enzyme and detection of the key intermediate in clinical specimens taken from patients being treated with the topo I inhibitor topotecan. Because available antibodies were not sufficiently sensitive at the start of this project, we identified a highly specific human SCL-70 antibody from a patient with scleroderma, which allowed quantitative determination of topo I copy number in HeLa and HT-29 cell lines. Additional refinements of the Western blot technique were accomplished to improve signal:noise ratio. In surgical tumor specimens, we found the median topo I level to be 30.1 x 10(5) copies/cell for gastric adenocarcinomas, compared to 18.4 x 10(5) copies/cell for normal gastric mucosae in the same samples. For lung adenocarcinoma, the median protein level was 21.5 x 10(5) copies/cell, compared with the normal tissue counterpart protein level of 12.7 x 10(5) copies/cell. The median tumor:normal ratios from paired samples of these tumor types were 1.51 and 1.84, respectively. As part of a Phase II study evaluating the efficacy of topotecan (1.5-2.0 mg/m2 daily for 5 days) in upper gastrointestinal malignancies, we obtained tumor and normal mucosa biopsies in 11 patients with gastric or esophageal cancer, 30 min after administration on day 4 or 5. Three patients with gastric adenocarcinoma had stable disease as their best response, with the remainder of patients progressing. Improvement in Western blotting methodology allowed the quantitation of topo I levels in these gastric and esophageal cancer biopsies, which could be augmented by brief heating to release complexed topo I. We were also able to directly visualize high molecular weight topo I-containing bands, which were shown to be cleavable complexes by heat reversal, with restoration of the topo I Mr 100,000 band. Using this heat reversal technique, we determined the presence of cleavable complex in a total of 7 of 11 patient biopsy samples (5 tumors and 2 normal mucosae). In patients treated with topotecan on this dose and schedule, we determined that a median of 73% of the total tumor topo I was involved in cleavable complex (range, 18.3-91%). The intensity of the Mr 100,000 topo I band in biopsy specimens of patients receiving topotecan represented "free" or noncomplexed topo I. The median copy number for the residual, noncomplexed topo I (n = 11) was 7.36 x 10(5) copies/cell, significantly less than the median of 30.1 x 10(5) copies/cell for random tumor specimens from patients with gastric adenocarcinomas (P < 0.001). Pharmacodynamic analysis demonstrated a negative correlation between the noncomplexed topo I copy number and topotecan area under the curve (Spearman rank test: r(s) = -0.81, P = 0.003). Nonlinear regression analyses of these data were best fit with an inhibitory maximum effect model, yielding parameter estimates for Emax and EC50 of 29.3 x 10(5) copies/cell (coefficient of variation = 22%) and 43.1 ng x h/ml (coefficient of variation = 27%), respectively. Through a series of careful modifications and refinements, we have improved the Western blot assay for topo I for use in clinical monitoring. We have demonstrated the ability to directly visualize cleavable complex in patients being treated with topo I inhibitor therapy and have directly quantitated free topo I, as well as the key topo I intermediate (cleavable complex), in biopsy specimens obtained from pat

Effects of PALA on the pharmacokinetics of 5-fluorouracil

N-(phosphonacetyl)-L-aspartate (PALA) modulates the activity of 5-fluorouracil (5-FU) by inhibiting pyrimidine biosynthesis. A cross-over study was conducted to determine whether PALA affects the pharmacokinetic parameters of 5-FU in patients given 5-FU/folinic acid (FA). Six patients (3 males, 3 females) aged 63 4.3 (mean SD) years (body surface area of 1.84 18 m2) with metastatic colorectal carcinoma were given two courses of treatment. The treatment consisted of 250 mg/m2 of PALA on day 1 followed by 20 mg/m2 FA and 400 mg/m2 5-FU (5 min i.v. bolus injection) on days 2-5 in one cycle of treatment (PALA+). In another treatment cycle, these doses of 5-FU and FA were given for all 5 days without PALA (PALA-). The two courses were given four weeks apart. It was determined by random selection whether the course with PALA was given before or after the course without PALA. Blood samples were collected over a period of three hours, starting from the beginning of 5-FU infusion on days 2 and 5 of both courses. Plasma concentrations of 5-FU were determined by an HPLC technique. Pharmacokinetic parameters were calculated using a non-compartmental model. While there were no significant differences between pharmacokinetic parameters in the PALA+ vs PALA- courses, there was a trend towards a decreasing area under the curve (AUC) and increasing clearance (Cl) in PALA+ courses of treatment.

Decreased urinary excretion of beta-glucuronidase in sickle cell anemia in Nigeria

The activities of five lysosomal hydrolases--namely beta-glucuronidase, beta-hexosaminidase, beta-galactosidase, alpha-galactosidase, and alpha-mannosidase--were measured in the plasma and urine of children (ages, 7 to 15 years) with sickle cell anemia (n = 11) and controls (n = 11) from Jos, Nigeria. The presence of SS hemoglobin was confirmed by electrophoresis of red cell hemolysates. Albuminuria was absent in all of the patients with sickle cell anemia. The creatinine-indexed urinary activity level (units of enzyme activity/milligrams creatinine) and the fractional enzyme excretion (FEE) value, which is defined as the ratio of enzyme clearance to creatinine clearance, were determined for each of the five lysosomal enzymes and compared between the two groups. The mean FEE values for beta-glucuronidase and alpha-galactosidase in the sickle cell patients were 10- and 3.5-fold lower, respectively, than the corresponding control values, and these differences were statistically significant (p < .03) for both enzymes; however, beta-hexosaminidase, beta-galactosidase, and alpha-mannosidase levels in urine were not different between the two groups. When indexed to creatinine, a comparison of the urinary enzyme levels of control and sickle cell patients showed significant differences for beta-glucuronidase (p < .01) and alpha-galactosidase (p < .05) but not for the other three enzymes. Differences in level of plasma enzyme activity between control and sickle cell patients were not significant, except for alpha-galactosidase (p < .05), which was increased slightly (25%) in the sickle cell group. These data indicate that there may be abnormalities in the metabolism of lysosomal enzymes in the kidneys of patients with sickle cell anemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Biochemical analysis of the transducin-phosphodiesterase interaction

In vertebrate rod cells, the activated alpha-subunit of rod transducin interacts with the gamma (regulatory) subunits of phosphodiesterase to disinhibit the catalytic subunits. A 22-amino acid long region of rod transducin involved in phosphodiesterase activation has recently been identified. We have used peptides from this region of rod transducin and from several other G protein alpha-subunits to study the nature and specificity of the G protein alpha-effector interaction. Although peptides derived from rod transducin, cone transducin and gustducin are similar, only the rod peptide is capable of activating rod phosphodiesterase. Using substituted peptides we have identified five residues on one exposed face of rod transducin as important to phosphodiesterase activation. These results disagree with previous models which propose that loop regions of rod transducin interact with phosphodiesterase gamma.

An evaluation of several adjuvant emulsion regimens for the production of polyclonal antisera in rabbits

Emulsion adjuvants have been used for production of polyclonal antisera in rabbits (Oryctolagus cunniculi) for decades. Complete Freund's adjuvant has a reputation as a very effective immunoenhancer, but adverse physiological effects, including fever, inflammation and sterile abscess formation, have prompted a search for alternatives to complete Freund's. In this study, we quantitatively compared five adjuvant regimens: (a) a primary inoculation with complete Freund's followed by three boosts with incomplete Freund's; (b) four serial inoculations of incomplete Freund's adjuvant augmented with 6-bromoguanisine; (c) four serial inoculations with RIBI's MPL + TDM + CWS adjuvant emulsion; (d) four serial inoculations with Montanide ISA 50 emulsion; and (e) four serial inoculations with Montanide ISA 70 emulsion. We chose a small (12 amino acid) chain polypeptide coupled to bovine serum albumin as our test antigen. When compared, no system could be seen to be significantly better than a regimen of a primary immunization with complete Freund's adjuvant followed by serial reimmunization with incomplete Freund's adjuvant. The commercially available RIBI adjuvant produced significantly lower antibody levels, while other systems produced essentially equivalent levels. With all five adjuvants, antibody quantities plateaued after the second injection and further immunization did not increase titers significantly. Boost injections did yield greater intradermal tissue reaction than primary inoculations, and intramuscular inoculum volumes of 0.4 cc caused chronic lesions still detectable by the gross necropsy 2 weeks after the final injection.

Systems of standards for community health services in Australia

This paper describes how the Australian Community Health Association (ACHA) has facilitated the development of quality assurance systems for community health services in Australia. The systems are based on the standards and review process produced by the Community Health Accreditation and Standards Project, known by its acronym "CHASP'. The paper outlines principles and organisation of community health services in Australia and some background to their development. It then considers what kind of standards and quality assurance methods are appropriate for community health services. The CHASP model of standards and its associated review process is explained. The paper discusses how the ACHA has worked with various states in Australia to establish systems of standards based on the CHASP work. It concludes by looking at some constraints and opportunities in developing CHASP, and some future directions.

Review and accreditation of community health centres

The Community Health Accreditation and Standards Project (CHASP) was developed specifically for reviewing community-based health services. It is currently being developed in a number of States and the Australian Community Health Association is looking to develop the national auspice. The development of area health services in New South Wales, however, is going to require a co-operative approach with the existing system of hospital accreditation.

A herpesvirus antigen in human premalignant and malignant cervical biopsies and explants

Cervical biopsies and explant cultures from patients with squamous metaplasia, various grades of dysplasia, carcinoma in situ (CIS), and invasive squamous cell carcinoma were screened for VP143, an early nonstructural polypeptide of herpes simplex virus type 2 (HSV-2), VP143 was identified in 31% of biopsies exhibiting severe dysplasia, 29% with CIS, and 41% with invasive squamous cell carcinoma. Similar results were obtained when explants derived from these biopsies were examined for VP143. The expression of the protein persisted in passaged subcultures in four of five invasive carcinomas which originally contained VP143. Staining for VP157, the major capsid protein of HSV-2, was absent. Furthermore, virus structures were not seen by electron microscopy and infectious virus was not isolated from cell cultures inoculated with biopsy extracts. These results suggest that VP143 was expressed in the premalignant and malignant cervical cells in the absence of productive viral infection. Thus, a fragment of the HSV-2 genome was retained within the cells, the expression of which resulted in the production of VP143.