Population Pharmacokinetics of Liposomal Irinotecan in Patients With Cancer.

Nanoliposomal irinotecan (nal-IRI) is a liposomal formulation of irinotecan with a longer half-life (t1/2 ), higher plasma total irinotecan (tIRI), and lower SN-38 maximum concentration (Cmax ) compared with nonliposomal irinotecan. Population pharmacokinetic (PK) analysis of nal-IRI was performed for tIRI and total SN-38 (tSN38) using patient samples from six studies. PK-safety association was evaluated for neutropenia and diarrhea in 353 patients. PK-efficacy association was evaluated from a phase III study in pancreatic cancer NAPOLI1. Efficacy was associated with longer duration of unencapsulated SN-38 (uSN38) above a threshold and higher Cavg of tIRI, tSN38, and uSN38. Neutropenia was associated with uSN38 Cmax and diarrhea with tIRI Cmax . Baseline predictive factors were race, body surface area, and bilirubin. Analysis identified PK factors associated with efficacy, safety, and predictive baseline factors. The results support the benefit of nal-IRI dose of 70 mg/m2 (free-base; equivalent to 80 mg/m2 salt base) Q2W over 100 mg/m2 Q3W.

Natural regulatory (CD4+CD25+FOXP+) T cells control the production of pro-inflammatory cytokines during Plasmodium chabaudi adami infection and do not contribute to immune evasion.

Different functions have been attributed to natural regulatory CD4+CD25+FOXP+ (Treg) cells during malaria infection. Herein, we assessed the role for Treg cells during infections with lethal (DS) and non-lethal (DK) Plasmodium chabaudi adami parasites, comparing the levels of parasitemia, inflammation and anaemia. Independent of parasite virulence, the population of splenic Treg cells expanded during infection, and the absolute numbers of activated CD69+ Treg cells were higher in DS-infected mice. In vivo depletion of CD25+ T cells, which eliminated 80% of CD4+FOXP3+CD25+ T cells and 60-70% of CD4+FOXP3+ T cells, significantly decreased the number of CD69+ Treg cells in mice with lethal malaria. As a result, higher parasite burden and morbidity were measured in the latter, whereas the kinetics of infection with non-lethal parasites remained unaffected. In the absence of Treg cells, parasite-specific IFN-gamma responses by CD4+ T cells increased significantly, both in mice with lethal and non-lethal infections, whereas IL-2 production was only stimulated in mice with non-lethal malaria. Following the depletion of CD25+ T cells, the production of IL-10 by CD90(-) cells was also enhanced in infected mice. Interestingly, a potent induction of TNF-alpha and IFN-gamma production by CD4+ and CD90(-) lymphocytes was measured in DS-infected mice, which also suffered severe anaemia earlier than non-depleted infected controls. Taken together, our data suggest that the expansion and activation of natural Treg cells represent a counter-regulatory response to the overwhelming inflammation associated with lethal P.c. adami. This response to infection involves TH1 lymphocytes as well as cells from the innate immune system.

SCH 503034, a mechanism-based inhibitor of hepatitis C virus NS3 protease, suppresses polyprotein maturation and enhances the antiviral activity of alpha interferon in replicon cells.

Cleavage of the hepatitis C virus (HCV) polyprotein by the viral NS3 protease releases functional viral proteins essential for viral replication. Recent studies by Foy and coworkers strongly suggest that NS3-mediated cleavage of host factors may abrogate cellular response to alpha interferon (IFN-alpha) (E. Foy, K. Li, R. Sumpter, Jr., Y.-M. Loo, C. L. Johnson, C. Wang, P. M. Fish, M. Yoneyama, T. Fujita, S. M. Lemon, and M. Gale, Jr., Proc. Natl. Acad. Sci. USA 102:2986-2991, 2005, and E. Foy, K. Li, C. Wang, R. Sumpter, Jr., M. Ikeda, S. M. Lemon, and M. Gale, Jr., Science 300:1145-1148, 2003). Blockage of NS3 protease activity therefore is expected to inhibit HCV replication by both direct suppression of viral protein production as well as by restoring host responsiveness to IFN. Using structure-assisted design, a ketoamide inhibitor, SCH 503034, was generated which demonstrated potent (overall inhibition constant, 14 nM) time-dependent inhibition of the NS3 protease in cell-free enzyme assays as well as robust in vitro activity in the HCV replicon system, as monitored by immunofluorescence and real-time PCR analysis. Continuous exposure of replicon-bearing cell lines to six times the 90% effective concentration of SCH 503034 for 15 days resulted in a greater than 4-log reduction in replicon RNA. The combination of SCH 503034 with IFN was more effective in suppressing replicon synthesis than either compound alone, supporting the suggestion of Foy and coworkers that combinations of IFN with protease inhibitors would lead to enhanced therapeutic efficacy.

Regulation of intercellular adhesion molecule-1 gene by tumor necrosis factor-alpha is mediated by the nuclear factor-kappaB heterodimers p65/p65 and p65/c-Rel in the absence of p50.

Human intercellular adhesion molecule-1 (ICAM-1) plays an important role in immune responses as the major specific ligand for the beta2-integrins LFA-1 and Mac-1. During the inflammatory process, ICAM-1 expression is stimulated by various proinflammatory cytokines. We have examined the mechanisms of transcriptional control involved in the stimulation of ICAM-1 gene expression by tumor necrosis factor-alpha (TNF-alpha) and by the nuclear factor-kappaB (NF-kappaB) family of transcription factors in the Ad5-transformed human embryonal kidney cell line 293. A proximal site (5'-TTGGAAATTCC-3') mapping at position -228 from the ATG and known to mediate TNF-alpha responsiveness in endothelial cells is also critical for TNF-alpha responsiveness in 293 cells. However, unlike endothelial cells, electrophoretic mobility shift assays, using whole-cell extracts prepared from TNF-alpha-treated cells, showed that TNF-alpha induces the formation of a specific kappaB binding complex, mainly composed of NF-kappaB subunits RelA and c-Rel. Electrophoretic mobility shift assays done with 293 cells transfected with p50, p65, or both subunits showed that p50 only has a weak ability to bind the proximal ICAM-1 NF-kappaB site. Another element exhibiting sequence homology with NF-kappaB binding sites and located at position -540 relative to the mRNA cap site was found to be involved in the basal activity of the ICAM-1 promoter, is not required for TNF-alpha responsiveness, and does not bind NF-kappaB subunits. Whereas transactivation of the ICAM-1 promoter by p65 requires the proximal NF-kappaB site, deletion mutant analysis showed that p50 and, to a greater extent, p52 transactivate reporter plasmids lacking NF-kappaB sites, suggesting the presence of other p50/p52 responsive element(s).

The effect of variance function estimation on nonlinear calibration inference in immunoassay data.

Often with data from immunoassays, the concentration-response relationship is nonlinear and intra-assay response variance is heterogeneous. Estimation of the standard curve is usually based on a nonlinear heteroscedastic regression model for concentration-response, where variance is modeled as a function of mean response and additional variance parameters. This paper discusses calibration inference for immunoassay data which exhibit this nonlinear heteroscedastic mean-variance relationship. An assessment of the effect of variance function estimation in three types of approximate large-sample confidence intervals for unknown concentrations is given by theoretical and empirical investigation and application to two examples. A major finding is that the accuracy of such calibration intervals depends critically on the nature of response variance and the quality with which variance parameters are estimated.

The effects of tropicamide on mydriasis in young rats exhibiting a natural deficit in passive-avoidance responding.

The young rat at post-natal day 18-22 exhibits a natural deficit in passive-avoidance responding that can be corrected with the acute systemic administration of different cholinomimetic drugs, such as tacrine. In order to evaluate the generality of this apparent cholinergic hypofunction, different doses of the anticholinergic agent tropicamide, were administered either systemically or dropped directly into the eye of young or adult rats. Tropicamide produced mydriasis in a dose-dependent manner. The ED50 for tropicamide dropped into the eye was 0.025% for adult rats and 0.12% for young rats. When doses between 0.3 and 100 mg/kg were delivered systemically, the mean time course for recovery to baseline pupil size was accelerated in young rats. The average time to recovery across all doses was 112 +/- 27 min (mean+/-SE) for young rats and 274 +/- 70 min for adults. When subcutaneous tacrine was given immediately to young rats after training in a passive-avoidance response (PAR) task, retention was enhanced at testing 24 hours later in a dose-dependent manner. The response latencies were statistically different from saline-treated controls at doses of 0.003 and 0.01 mg/kg. This was not observed in adult rats. Taken together these results suggest that the PAR, along with the mydriacyl response of the young rat to tropicamide, may be regulated by a system of subsensitive cholinergic receptors.

Promoting social health in northern Saskatchewan.

In response to concern about social health problems in Northern Saskatchewan, a Working Group on Social Health was established in 1989 in the Research and Development Committee of Northern Medical Services. The Group formulated a concept of mental health in social terms; found and interpreted indicators of the extent of social health problems; identified major determinants of social health problems, barriers to effective coping and problems in providing adequate support and services; and identified strategies and program models that could be more effective in promoting social health in this region. Indicators of problems and underlying determinants are discussed, along with strategies for change. These strategies are based on a community development model, and incorporate innovation and reaffirmation of values and ways that have traditionally given people strength.

Effects of adrenocorticotropin on adrenal and plasma 11 beta-hydroxyandrostenedione in the guinea pig and determination of its relative androgen potency.

In order to gain a better understanding of adrenal steroid production in guinea pigs, adrenocorticotropin (ACTH) was administered to castrated adult guinea pigs and a series of C-21 and C-19 steroid levels were determined in both adrenals and plasma over a 6-h period. After injection of ACTH, adrenal cortisol and corticosterone concentrations were stimulated by almost 40- and threefold, respectively, whereas the content of C-21 steroid precursors, namely pregnenolone, 17-hydroxypregnenolone, progesterone, and 17-hydroxyprogesterone, was stimulated by two- to 10-fold. Increases of C-19 steroid levels, namely dehydroepiandrosterone (DHEA), androstenedione (4-DIONE), testosterone, and 11 beta-hydroxyandrostenedione (11 beta-DIONE) ranging from 1.5 to eight times were also observed in the adrenals. In castrated guinea pigs, basal plasma DHEA, 4-DIONE, and testosterone levels were undetectable by radioimmunoassay, whereas 11 beta-DIONE concentrations were in a range similar to those in intact animals. In plasma, ACTH had a marked effect on corticosterone, cortisol, and 11 beta-DIONE. The present results indicate that although guinea pig adrenals synthesized several C-19 steroids, only 11 beta-DIONE was secreted by the adrenals into circulation even after administration of ACTH. The biological activity of this hydroxylated C-19 steroid was then assessed by using silastic implants in castrated guinea pigs, and it was shown that plasma 11 beta-DIONE concentrations increased by threefold and had no effect on prostate weight. Moreover, by using ZR-75-1 cells, a mammary cancer cell line extremely sensitive to androgens, we demonstrated that 11 beta-DIONE had an androgenic potency 35-fold less than that of dihydrotestosterone.

Administration of pregnenolone and dehydroepiandrosterone to guinea pigs and rats causes the accumulation of fatty acid esters of pregnenolone and dehydroepiandrosterone in plasma lipoproteins.

Steroids were administered continuously to guinea pigs and rats using subcutaneously applied silastic tubing implants, and the effects on circulating steroid and steroid conjugate levels were monitored. Using implants filled with pregnenolone, we observed that pregnenolone had a marked effect on increasing the levels of its fatty acid-esterified derivative, while dehydroepiandrosterone-releasing implants produced a rise in circulating nonconjugated dehydroepiandrosterone, androst-5-ene-3 beta,17 beta-diol, androstenedione, testosterone, and lipoidal derivatives of both dehydroepiandrosterone and androst-5-ene-3 beta,17 beta-diol. Implants filled with androstenedione produced a 20-fold increase in plasma androstenedione levels relative to untreated controls and a corresponding five-fold increase over control testosterone levels. No fatty acid-esterified derivative of testosterone could be detected within the plasma. Lipoproteins were isolated from both rats and guinea pigs treated with implants filled with pregnenolone or dehydroepiandrosterone. The steroid and steroid fatty acid esters present in each fraction were analyzed, revealing that approximately 75% of all the fatty acid esters of pregnenolone recovered in the lipoproteins was localized within the high-density lipoprotein (HDL) fraction of both guinea pig and rat plasma. Similarly, lipoidal dehydroepiandrosterone was found associated predominantly with the low-density lipoprotein and HDL fractions in the guinea pig, while in the rat this steroid conjugate was exclusively within the HDL fraction. High-density lipoprotein-incorporated tritiated pregnenolone fatty acid esters and dehydroepiandrosterone fatty acid esters were injected into castrated male guinea pigs to study the fate of these complexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies of adrenal steroidogenic enzymes in guinea pigs.

In the present study we found that 3 beta-hydroxysteroid dehydrogenase 4-ene-5-ene-isomerase (3 beta-HSD), 17-hydroxylase and 17,20-lyase (P-450c17), and 21-hydroxylase (P-450c21) activities in a suspension of cells from guinea pig zona reticularis (RE) were 10- to 15-fold less than those measured in cells from zona fasciculata-glomerulosa (FG). Whereas the secretion of cortisol and C-19 steroids was remarkably increased during treatment of FG cells with adrenocorticotropic hormone (ACTH), no response could be detected when using cells from zona RE. By contrast, the measurement of a series of C-21 and C-19 steroids shows that the concentrations of several steroids were greater in the zona RE than in the zona FG. In addition, using Northern blot analysis, we have observed that the basal steady-state levels of mRNA for cholesterol side-chain cleavage (P-450scc), 3 beta-HSD, P-450c21, P-450c17, and P-450c11 were in the same range in the two zones and an administration of ACTH caused, in both zona FG and zona RE, a two- to threefold decrease in P-450c17 and P-450c21 steady-state mRNA levels, whereas P-450c11, 3 beta-HSD, and P-450scc steady-state mRNA levels remained unchanged. Our data suggest the presence of some factor(s) capable of rapidly deactivating the steroidogenic enzymes in the zona RE.

Adrenal steroidogenesis in the guinea pig: effects of androgens.

In humans, the onset of adrenache has been found to occur with the appearance of the zona reticularis, the inner zone of the adrenal cortex. Since an increase in the volume of adrenal cortex during maturation in the guinea pig has been associated with the growth of the zona reticularis, we were interested in investigating the changes in adrenal steroidogenesis during maturation in this species. In addition, the effect of androgens on adrenal steroidogenesis was studied. We demonstrated that between 1 and 10 weeks of age, a period of maximal growth of the adrenals in the guinea pig, there is a decrease in the concentrations of adrenal pregnenolone, cortisol, dehydroepiandrosterone, testosterone, androstenedione, and 11 beta-hydroxyandrostenedione, suggesting lower steroid production by the guinea pig adrenals. In plasma, we observed that the concentration of 11 beta-hydroxyandrostenedione (the sole C19 steroid present after castration) remained unchanged during maturation, while cortisol and corticosterone were lower between 1 and 4 weeks of age. Although castration as well as the administration of the antiandrogen flutamide had no effect on adrenal steroidogenesis, dihydrotestosterone caused an inhibition of cortisol and corticosterone levels in the adrenals while the concentrations of progestins (namely, pregnenolone, 17-hydroxypregnenolone, progesterone, and 17-hydroxyprogesterone) tended to increase in the adrenals, thus suggesting that dihydrotestosterone induces a blockade in the steroidogenic pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Steroidogenesis in guinea pig adrenal cortex: effects of ACTH on steroid secretion and steroidogenic enzyme activities and expression.

In this study, we investigated guinea pig adrenal steroidogenesis, specially, C19 steroid production. Analysis of adrenal steroids by high performance liquid chromatography and gas chromatography indicated the presence of androstenedione and 11ß-hydroxyandrostenedione. Adrenal androstenedione and 11ß-hydroxyandrostenedione levels were stimulated by ACTH administration while only 11ß-hydroxyandrostenedione was increased in plasma. In vitro studies using adrenal cortex cells in primary culture confirmed that 11ß-hydroxyandrostenedione is the major C19 steroid secreted. The chronic treatment of guinea pig with ACTH stimulated all adrenal post-pregnenolone enzyme activities and decreased P 450c17 mRNA levels while P 450scc, 3ß-hydroxysteroid dehydrogenase and P450c11 mRNAs remained unaffected. Treatment of adrenal cells in primary culture with ACTH for 72 h changed the distribution of steroids secreted and decreased 21-hydroxylase activity while 17α-hydroxylase and 17,20-lyase activities were increased favoring C19 steroid production. In ACTH-treated cells, the mRNA levels for P450c21 and P450c17 increased and reached a peak at 18 h. Our data indicate that treatment with ACTH stimulates adrenal steroidogenic capacity by increasing steroid secretion and causes transcriptional and post-transcriptional effects on steroidogenic enzymes gene expression. Finally, the direct action of steroids on steroid production by adrenal cells in primary culture was investigated. Our data indicate that steroids themselves increase C19 steroid synthesis and inhibit glucocorticoid production without affecting gene expression for steroidogenic enzymes.

Steroid fatty acid esters in adrenals and plasma: effects of ACTH.

The presence and production of 5-ene-steroid fatty acid esters (SFA) has been previously reported in bovine adrenals. A study was conducted, using a series of chromatographic procedures and radioimmunoassays, to determine the levels of SFA in adrenals from man, cattle, dog, rat and guinea-pig, and to assess, in both rats and guinea-pigs, the effect of ACTH on SFA production by adrenals and their subsequent secretion into the circulation. The effects of ACTH on plasma SFA and non-conjugated steroid levels were also investigated in human subjects. Our data indicated that adrenal pregnenolone fatty acid ester (PREG-FA) levels were below 40% of PREG levels in cattle, dog, rat and guinea-pig while, in man, PREG-FA levels were threefold those of PREG. A large proportion of dehydroepiandrosterone (DHEA) and 5-androstene-3 beta, 17 beta-diol were present as fatty acid ester derivatives in the adrenals of all species, with the exception of cattle. In both rats and guinea-pigs, administration of ACTH caused a sharp increase in adrenal PREG of approximately threefold which lasted for 6 h, while the concentration of adrenal PREG-FA was slightly increased for a short time. In plasma, however, a marked rise in PREG-FA occurred, while the changes in PREG levels were much lower than those of its acylated counterpart. In man, PREG and DHEA concentrations were rapidly stimulated two-fold in the first 30 min following the administration of ACTH, while PREG-FA and DHEA-FA levels were increased by approximately 2.5-fold (P less than 0.01) at 120 and 180 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Production and secretion of C-19 steroids by rat and guinea pig adrenals.

The concentrations of C-19 steroids were measured in guinea pig and rat adrenals before and after castration as well as after stimulation with adrenocorticotropin hormone (ACTH). Characterization of adrenal C-19 steroids was also carried out by isolation with high-performance liquid chromatography and gas chromatography/mass spectrometry (GC/MS). From radioimmunoassay (RIA) data, androstenedione (4-DIONE) and 11 beta hydroxyandrostenedione (11 beta-DIONE) were the major C-19 steroids found in guinea pig adrenals, and castration induced a decrease of 4-DIONE levels only while all other C-19 steroids remained unchanged. In rat adrenals, the major C-19 steroids were 4-DIONE and testosterone, and they were also markedly inhibited after castration. With the exception of 11 beta-DIONE, all other C-19 steroids in circulation were eliminated after castration in both animals species. After ACTH administration in the guinea pig, adrenal 4-DIONE and 11 beta-DIONE levels were markedly stimulated, while an increase of only 11 beta-DIONE was observed in plasma. In the rat, ACTH had a small stimulatory effect on adrenal 52-androstane-3 alpha, 17 beta-diol (3 alpha-DIOL) and plasma 11 beta-DIONE levels. Analysis of guinea pig adrenal steroids by GC/MS confirmed the presence of C-19 steroids in adrenals (namely, 4-DIONE and 11 beta-DIONE) while, in the rat, this could not be confirmed. Our data indicate that production of C-19 steroids occurs in guinea pig adrenals, and 11 beta-DIONE is the major C-19 steroid as well as the only C-19 steroid secreted into the circulation. In the rat, the production of C-19 steroids detected by RIA is not supported by GC/MS data.

Comparison of residual C-19 steroids in plasma and prostatic tissue of human, rat and guinea pig after castration: unique importance of extratesticular androgens in men.

The concentrations of dehydroepiandrosterone (DHEA), its sulfate (DHEAS), androstenedione (A-dione), testosterone (T) and dihydrotestosterone (DHT) have been measured before and after castration in men and two animal models, namely the rat and the guinea pig. In adult men, the pre-castration levels of plasma DHEAS and DHEA were measured at 1839 +/- 320 and 2.4 +/- 0.5 ng/ml, respectively, while in both animal models, the concentrations of these two steroids were below 0.3 ng/ml. Orchiectomy in men reduced plasma T and DHT levels from 2.9 +/- 0.1 and 0.60 +/- 0.10 to 0.42 +/- 0.21 and 0.05 +/- 0.01 ng/ml (P less than 0.01), respectively, while there was no significant effect observed on DHEAS, DHEA and A-dione levels. By contrast, castration in the rat reduced the low levels of circulating DHEA and A-dione below the detection of the radioimmunoassay (RIA) used. In castrated guinea pig, a small quantity of plasma A-dione (0.07 +/- 0.02 ng/ml) was measured while DHEA was undetectable. Moreover, in the rat and guinea pig, plasma T and DHT levels became undetectable. Following administration of the antiandrogen Flutamide for two weeks in the castrated rat and guinea pig, prostate weight was not further reduced, thus indicating that there is no significant androgenic activity left following castration of these two species. In fact, castration in the rat and guinea pig caused a decrease in prostatic levels of DHT from 4.24 +/- 0.351 and 9.42 +/- 1.43 ng/g, respectively, to undetectable levels. In men, on the other hand, the prostatic DHT levels were only inhibited from 5.24 +/- 0.59 to 2.70 +/- 1.50 ng/g, respectively. As expected, when Flutamide was administered to the rat and the guinea pig, the levels of prostatic steroids remained undetectable while, in men, the DHT content in the prostate was further reduced to undetectable values. In summary, the plasma levels of DHEAS, DHEA, delta 4-dione are markedly different between men and both animal models used and furthermore, measurements of prostatic levels of androgens suggest that the high plasma levels of these steroids are likely responsible for the presence of important amounts of DHT in human prostate after castration.

Work in progress: temporal energy hybrid subtraction in intravenous digital subtraction angiography.

A preliminary investigation of the feasibility and practical clinical utility of combined temporal energy (hybrid) subtraction for intravenous digital subtraction angiography (DSA) was performed in 19 selected patients. Studies of carotid, aortic arch, pulmonary, and aortorenal vessels were obtained. Soft-tissue misregistration artifacts were effectively removed with hybrid subtraction. Image integration was used to produce a signal-to-noise ratio equivalent to that of single frame temporal subtraction. Diagnostic improvements were produced in 20% of the examinations. Hybrid subtraction techniques resulted in an average increase of incident radiation dose to the skin of 15%.

Clinical application of hybrid subtraction digital angiography: preliminary results.

The clinical application of hybrid subtraction in digital fluoroscopy of the vasculature is reported in our first 30 patients studied. Hybrid subtraction combines the advantages of temporal and dual energy subtraction techniques to achieve simultaneous elimination of overlying bone, soft tissue, and motion induced artifacts. Hybrid subtraction improved the subjective appearance of an image in 19 of 30 (63%) studies but additional diagnostic information was only revealed in 11 of 30 (37%) patients.

Objective performance measurements versus perceived image quality in intensified fluoroscopic or photospot images.

The relationship between perceived image quality and measurable performance parameters of an intensified fluoroscopic image, viewed via a TV monitor or recorded on 105mm film, was investigated. Four specially manufactured image tubes, differing significantly in x-ray absorption efficiency, spatial resolution, and/or contrast resolution, were studied. Quantitative measurements of tube performance included the conversion factor, the quantum detection efficiency, the limiting resolution, the contrast ratio, and the contrast-detail characteristics. An assessment of the quality of clinical images was made by two radiologist-observers, working independently and without knowledge of any quantitative results. The observers were asked to rate the noise, lag, resolution, and contrast of the images during a variety of fluoroscopic procedures on each tube. While general agreement was found between the quantitative measurements and the radiologists' perceptions of image quality, the noise and contrast performance of an intensifier had greater influence on the radiologists' judgment of image quality than did resolution.