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Biomedical subjects

W Lew

Publications and source records attributed to W Lew.

At least 19 recordsLinked to original sources
PubMed2004

Psoriasis genomics: analysis of proinflammatory (type 1) gene expression in large plaque (Western) and small plaque (Asian) psoriasis vulgaris.

BACKGROUND: Type 1 T cells are hypothesized to be central in the immunopathogenesis of psoriasis. Through elaboration of interferon (IFN)-gamma, type 1 T cells regulate the expression of many 'downstream' inflammatory genes, including an array of chemokines that regulate leucocyte trafficking and activation in skin lesions. Accordingly, disease progression and/or severity might be controlled by the degree to which differing cytokines and chemokines are overexpressed in focal skin regions. To examine this possibility, we studied two forms of chronic psoriasis vulgaris that differ significantly in overall severity and progression: small plaque (SP) psoriasis occurring in Korean patients, and large plaque (LP) psoriasis occurring in North American patients. OBJECTIVES: To characterize LP and SP psoriasis vulgaris with respect to expression of proinflammatory genes that define the type 1 T-cell axis in skin lesions [genes encoding interleukin (IL)-12, IFN-gamma, and IFN-gamma-regulated chemokines or inflammatory mediators]. METHODS: Total cellular RNA of skin samples from groups of patients with LP or SP psoriasis was analysed by quantitative reverse transcription-polymerase chain reaction (TaqMan analysis) to compare the differences in mRNA expression of genes related to the IFN-gamma pathway. RESULTS: The mRNA expression of keratin 16, CD25, IFN-gamma, IL-12 p40, signal transducer and activator of transcription-1, inducible nitric oxide synthase, IL-8, macrophage inflammatory protein-3alpha, monocyte chemoattractant protein-1, S100A12, IFN-gamma-inducible protein of 10 kDa, IFN-inducible T-cell alpha-chemoattractant and monokine induced by IFN-gamma was increased in the lesions of both LP psoriasis and SP psoriasis. However, IL-18 mRNA expression was significantly different in the lesions of LP psoriasis in comparison with those of SP psoriasis. CONCLUSIONS: The results indicate that proinflammatory type 1 genes regulated by IFN-gamma are similarly increased in both SP and LP psoriasis, but a potential difference in IL-18 exists between these disease forms. The consistent activation of this set of genes argues for a central role of IFN-gamma as a molecular regulator of inflammation in these distinct subtypes of psoriasis vulgaris. In contrast, disease extent/severity must be controlled by yet other factors.

Adult↗
PubMed2001

Fluorescent imaging and analysis with Typhoon 8600.

Current technologies in laser-based imaging systems for life science applications offer highly sensitive and quantitative detection of multiple labels. Typhoon 8600 variable mode imager is capable of fluorescence, storage phosphor, and chemiluminescence detection of gels and blots. The system delivers sensitive fluorescent detection of nucleic acids and proteins in both agarose and polyacrylamide gel formats. Detection and discrimination of multicolor fluorescent signals in fragment analysis, electromobility shift assays, Western blotting and other applications enhance the speed and accuracy of analysis.

DNA↗
PubMed2001

Chronotherapy and chronotoxicity of the cyclooxygenase-2 inhibitor, celecoxib, in athymic mice bearing human breast cancer xenografts.

PURPOSE: Inhibition of the enzyme cyclooxygenase with celecoxib is cytotoxic in a variety of solid tumor cell lines. Previous work has shown that by charting circadian rhythms, it has been possible to find optimal times to deliver a dose of drug, such that it is most efficacious in killing cancer cells and least harmful to normal tissues. Therefore, we examined the time dependence of toxicity (chronotoxicity) and of antitumor effects (chronotherapy) of celecoxib to determine optimal time of day for dosing with respect to light-dark cycles. EXPERIMENTAL DESIGN: Celecoxib was administered i.p. for 10 days (5 days on, 2 days off, 5 days on) to nude mice bearing s.c. breast xenografts. Body weight, peripheral blood cells, clinical chemistry, and tumor growth were monitored. RESULTS: The highest tolerance (100% survival) was found at 7 HALO and the least occurred at 17 h after light onset (HALO; 10% survival). Chronotherapy at a 20-mg/kg dose varied between the seven HALO evaluated and between the three breast tumors (MCF-7, ZR-75-30, and MDA-MB-468) studied. When the maximum tolerated dose (MTD) of celecoxib was optimized for each HALO, we found that at 7-10 HALO, the MTD was 25 mg/kg, whereas at 17-20 HALO; the MTD was only 10 mg/kg. Tumor regression was observed when dosing was done at 23 HALO to 7 HALO (5 a.m. to 1 p.m.), whereas no therapeutic response was observed when dosing was done at 10-13 HALO (4 p.m. to 7 p.m.), and rapid tumor growth was noted when dosing was done at 17 HALO (11 p.m.). CONCLUSIONS: Tumor growth response to the MTD at each HALO revealed that there was no clear relationship between dose administered and therapeutic response. COX-2 expression was not able to explain either the chronotherapy or the chronotoxicity results obtained.

Animals↗
PubMed2000

Carbocyclic influenza neuraminidase inhibitors possessing a C3-cyclic amine side chain: synthesis and inhibitory activity.

As part of our continuing work in the area of influenza neuraminidase inhibitors, a series of C3-aza inhibitors possessing a cyclic amine side chain was synthesized and evaluated for influenza neuraminidase inhibitory activity. Analogues possessing a six-, seven- and eight-membered ring, 4c-e, respectively, at the C3 position exhibited excellent influenza B neuraminidase inhibition.

Amines↗
PubMed2000

Anti-oxidant vitamins reduce normal tissue toxicity induced by radio-immunotherapy.

Our purpose was to determine whether the administration of anti-oxidant vitamins could reduce dose-limiting toxicity from radio-immunotherapy (RAIT) and thereby allow higher escalation of RAIT doses. Lipophilic vitamins A and E were administered i.p. and hydrophilic vitamin C was administered i.m. for 14 days (3 days pre-RAIT through 11 days post-RAIT) alone or with bone marrow transplantation (BMT) to either BALB/c mice for toxicity studies or to nude mice bearing s.c. GW-39 human colonic cancer xenografts for therapy studies. The maximal tolerated dose (MTD) of RAIT ((131)I-MN14 anti-CEA IgG) that results in no lethality was determined for mice that did not receive vitamins or BMT and those that did receive one or both interventions. Body weight, peripheral white blood cell (pWBC) and platelet (PLT) counts and tumor growth were also measured. Administration of vitamins (equivalent of 3.5 IU/day vitamin A, 0.107 IU/day vitamin E and 4.0 mg/day ascorbic acid) to mice along with BMT increased the MTD by 42% and reduced body weight loss associated with RAIT. Vitamins also reduced the magnitude of RAIT-induced myelosuppression. As early as day 7 after RAIT, vitamins increased WBC counts following both a 400 microCi and a 500 microCi dose. On day 14 after the 400 microCi dose of RAIT (day 7 post-BMT), the additive effect of BMT and vitamin could be detected. Tumor growth was not adversely affected by vitamin administration.

Animals↗
PubMed2000

Sphingomyelin potentiates chemotherapy of human cancer xenografts.

We propose that one manifestation of altered sphingolipid metabolism within tumor cells may be a reduced sensitivity to anti-cancer therapies because of an inability to produce a sufficient apoptotic signal via sphingomyelin hydrolysis to ceramide. If so, then sphingomyelin administration could reverse this effect and increase a tumor's sensitivity to chemotherapy. In vivo, intravenous sphingomyelin (10 mg/day, 7 days) potentiated 5-fluorouracil chemotherapy (0.45 mg/day, 5 days) when co-administered to HT29 human colonic xenograft-bearing nude mice. In vitro, sphingomyelin (SM) at its maximum tolerated concentration increased 5-fluorouracil and doxorubicin sensitivity of HCT15 and MOSER (1 mg/ml SM) and LS174T and SW480 human colonic tumor cells (0.1 mg/ml) approximately 100-300%. At 1 mg/ml SM, however, no effect was seen using HT29, LoVo and WiDr cells. There was no sensitization of normal human umbilical cord endothelial cells. Thus, sphingomyelin co-administration may be one method to improve the selective efficacy of chemotherapy in some tumors, possibly through enhancement of the apoptotic response.

Animals↗
PubMed2000

Plasma FLT3-L levels predict bone marrow recovery from myelosuppressive therapy.

BACKGROUND: During the recovery period after anticancer myelosuppressive therapy, hematopoietic progenitor cells become mitotically active in order to replenish the bone marrow compartment and remain hyperproliferative even after normalization of peripheral white blood cells and platelets. At this stage, the progenitors are more radiosensitive and chemosensitive. Dosing patients with additional cytotoxic therapy during this phase will likely result in more severe toxicity. For example, the authors have noted that the red bone marrow (RM) dose resulting from radioantibody therapy does not correlate with observed bone marrow toxicity. Several patients given similar RM doses had Grade 3 or 4 toxicity, whereas others had Grade 0-2 toxicity even though their white blood cell (WBC) and (PLT) counts were normal at the time of dosing. The goal of these studies was to establish a noninvasive predictive marker of bone marrow activity that could determine stem cell and progenitor cell recovery from previous myelosuppressive therapy. METHODS: A retrospective study was conducted to quantitate plasma levels of 5 cytokines regulating hematopoiesis, namely, 2 stimulatory fms-like tyrosine kinase (FLT3-L) and stem cell factor (SCF) and 3 inhibitory growth factors tumor necrosis factor-alpha (TNFalpha), tumor growth factor-beta, and macrophage inflammatory protein (MIP-1alpha), by immunoassay in 43 patients enrolled in clinical trials at Garden State Cancer Center in Belleville, New Jersey. All patients had had previous chemotherapy with a duration of 1-24 months. The serum cytokine values were correlated with the magnitude of leukopenia or thrombocytopenia following a single dose of radioantibody as the cytotoxic therapy. RESULTS: Plasma FLT3-L levels predicted excess platelet toxicity in 13 of 16 patients (mean = 225 +/- 106 pg/mL) and resulted in a false-positive in only 3 of 27 other patients (mean = 80 +/- 41 pg/mL). Plasma FLT3-L > 135 pg/mL resulted in 81% sensitivity and 89% and 86% specificity and accuracy, respectively, for predicting excess toxicity caused by additional cytotoxic therapy. The positive likelihood ratio was 7.5 (95% confidence interval, 2.5-22.5) and the negative likelihood ratio was 0.19 (95% confidence interval, 0.05-0.67). CONCLUSIONS: Elevated plasma FLT3-L in patients who previously received chemotherapy is a predictive measure of the stage of recovery of the bone marrow compartment. FLT3-L seems to identify the likelihood that the patient will experience Grade > or = 3 thrombocytopenia if additional cytotoxic therapy is administered. Knowledge of bone marrow activity should permit therapy that is more aggressive by establishing the earliest possible time for dosing with any cytotoxic agent for which myelosuppression is the dose-limiting toxicity.

Antineoplastic Agents↗
PubMed2000

Discovery and development of GS 4104 (oseltamivir): an orally active influenza neuraminidase inhibitor.

Rational drug design utilizing available X-ray crystal structures of sialic acid analogues bound to the active site of influenza virus neuraminidase has led to the discovery of a series of potent carbocyclic influenza neuraminidase inhibitors. From this series, GS 4104 (oseltamivir, TAMIFLU ) has emerged as a promising antiviral for the treatment and prophylaxis of human influenza infection. This article will summarize the design, discovery, and development of oseltamivir as an oral therapeutic to treat influenza infection.

Administration, Oral↗
PubMed2000

Metabolism of the influenza neuraminidase inhibitor prodrug oseltamivir in the rat.

The metabolism of [2-acetyl-(14)C]oseltamivir (GS4104, Ro 64-0796), the prodrug of the novel influenza neuraminidase inhibitor GS4071 (Ro 64-0802), was examined in rats after oral dosing. Intact oseltamivir was observed only in lung and urine, accounting for 37 and 15% of the total radioactivity in these samples, respectively. GS4071 was the major metabolite in plasma, tissues, and urine, and accounted for 32 to 56% of the radioactivity present in these samples. The second most abundant peak in these samples (13-24% of radioactivity) was a novel metabolite (M3). This metabolite was purified from urine of rats dosed orally with oseltamivir and was identified by liquid chromatography-mass spectrometry and NMR as the (R)-omega-carboxylic acid metabolite of oseltamivir. The omega-carboxylic acid metabolite of oseltamivir could not be produced in vitro. However, omega-hydroxylated products of oseltamivir were produced by rat liver microsomes. Both the (R)- and (S)-omega-hydroxylated products were observed, but formation of the (R)-isomer predominated. These data indicated that in the rat, oseltamivir was primarily metabolized to the active influenza neuraminidase inhibitor GS4071 and, to a lesser extent, to an (R)-omega-carboxylic acid metabolite.

Acetamides↗
PubMed1999

Chronotolerance of experimental radioimmunotherapy: clearance, toxicity, and maximal tolerated dose of 131I-anti-carcinoembryonic antigen (CEA) IgG as a function of time of day of dosing in a murine model.

The temporal variation in bone marrow proliferation has been used to help define the optimal time of day to dose with approximately 30 chemotherapeutic agents, so that treatment efficacy is maximised and toxicity is minimised. Since myelosuppression is also the dose-limiting toxicity for most forms of radioimmunotherapy, we hypothesised that time of day of administration might also influence tolerance for radioantibody therapy. Bone marrow proliferative activity in BALB/c mice was determined using cell cycle analysis of propidium iodide-stained bone marrow samples collected at 3 h intervals. Myelosuppression was determined at weekly intervals after a therapeutic dose of 131I-NP-4 anti-CEA (carcinoembryonic antigen) intact IgG at either 0900 h (2 h after light onset [HALO]), 1300 h (6 HALO) or 1600 h (9 HALO). The highest bone marrow proliferative activity was noted between 20 HALO (0300 h) and 4 HALO (1100 h), and the lowest activity could be measured at 10-13 HALO (1700-2000 h). Seven days after a maximal tolerated dose (MTD) of radioantibody, granulocyte reduction was 50% at both 2 and 6 HALO and only 32% at 9 HALO (P < 0.003). Fourteen days after radioantibody therapy, an 87% granulocyte suppression was observed in mice treated at 2 HALO and only a 64% granulocyte loss was noted in the 9 HALO treated group (P < 0.001). The 2 HALO group recovered earlier than the 9 HALO group (P < 0.013; 22% loss from the 2 HALO dose and 40% loss from the 9 HALO dose) on day 28 post-radioimmunotherapy. The difference in magnitude of neutropenia, rather than duration, was critical for establishing the MTD. A 30% increase in the MTD was possible if mice were dosed at 9 HALO (320 microCi) versus 2 HALO (240 microCi). These studies suggest that principles of chronobiology may govern the magnitude of toxicity and the highest dose tolerated in radioantibody therapy in the same way that it does for cytotoxic drug therapy.

Animals↗
PubMed1999

Importance of timing of radioimmunotherapy after granulocyte colony-stimulating factor administration for peripheral blood stem cell harvest.

Nine radioimmunotherapy (RAIT)-naive patients with medullary thyroid cancer received high doses of 131I-MN-14 F(ab)2 anti-carcinoembryonic antigen monoclonal antibody (232-486 mCi), five in combination with bone marrow harvest, without prior granulocyte colony stimulating factor (G-CSF) injections (group 1) and the other four using peripheral blood stem cell harvest (PBSCH) preceded by G-CSF administration of 10 microg/kg per day for 5 days for stem cell mobilization, 6-8 days before RAIT (group 2). The amounts of radioactivity (mCi) given in both groups were similar (312 +/- 93 versus 424 +/- 65; P = NS). The percent platelet loss at nadir, duration of grade 4 thrombocytopenia, and time to complete recovery (TTCR, measured from the day of treatment), were 83 +/- 17%, 2.5 +/- 0.7 days, and 45 +/- 8 days in group 1, respectively, compared with 88 +/- 6%, 3.0 +/- 2.6 days, and 50 +/- 24 days in group 2 (P = NS), respectively. In contrast, the percent WBC loss at nadir, duration of grade 4 leukopenia, and TTCR of WBCs were 72 +/- 12%, 0.0 +/- 0.0 day, and 42 +/- 12 days in group 1, respectively, compared with 93 +/- 3%, 8.0 +/- 3.6 days, and 263 +/- 136 days in group 2, respectively (P < 0.02, 0.03, and 0.05 for differences of percent loss, duration of nadir, and TTCR, respectively). The difference in WBC toxicity after RAIT with bone marrow harvest and PBSCH is thought to be due to the administration of G-CSF for stem cell mobilization within 1 week before RAIT, which may sensitize the "endogenous" granulocyte precursors to subsequent RAIT. Preclinical data of RAIT in mice showed that the time of G-CSF administration before RAIT is critical: increased WBC toxicity was seen in mice given RAIT 3 or 7 days after a 5-day course of G-CSF (81 and 57% WBC loss, respectively) compared with those given no G-CSF or G-CSF 10 or 14 days before RAIT (45-50%) WBC loss). In conclusion, our data indicate that the timing of RAIT after the administration of G-CSF for PBSCH may influence WBC toxicity and recovery after this treatment and may have important implications on the design of high-dose RAIT trials combined with PBSCH.

Adult↗
PubMed1998

Structure-activity relationship studies of novel carbocyclic influenza neuraminidase inhibitors.

A series of influenza neuraminidase inhibitors with the cyclohexene scaffold containing lipophilic side chains have been synthesized and evaluated for influenza A and B neuraminidase inhibitory activity. The size and geometry of side chains have been modified systematically in order to investigate structure-activity relationships of this class of compounds. The X-ray crystal structures of several analogues complexed with neuraminidase revealed that the lipophilic side chains bound to the hydrophobic pocket consisted of Glu276, Ala246, Arg224, and Ile222 of the enzyme active site. The structure-activity relationship studies of this series have also demonstrated remarkably different inhibitory potency between influenza A and B neuraminidase. This indicated that the lipophilic side chains had quite different hydrophobic interactions with influenza A and B neuraminidase despite their complete homology in the active site. Influenza B neuraminidase appeared to be much more sensitive toward the increased steric bulkiness of inhibitors compared to influenza A neuraminidase. From the extensive structure-activity relationship investigation reported in this article, GS 4071 emerged as one of the most potent influenza neuraminidase inhibitors against both influenza A and B strains.

Acetamides↗
PubMed1998

Characterization of human influenza virus variants selected in vitro in the presence of the neuraminidase inhibitor GS 4071.

An oral prodrug of GS 4071, a potent and selective inhibitor of influenza neuraminidases, is currently under clinical development for the treatment and prophylaxis of influenza virus infections in humans. To investigate the potential development of resistance during the clinical use of this compound, variants of the human influenza A/Victoria/3/75 (H3N2) virus with reduced susceptibility to the neuraminidase inhibitor GS 4071 were selected in vitro by passaging the virus in MDCK cells in the presence of inhibitor. After eight passages, variants containing two amino acid substitutions in the hemagglutinin (A28T in HA1 and R124M in HA2) but no changes in the neuraminidase were isolated. These variants exhibited a 10-fold reduction in susceptibility to GS 4071 and zanamivir (GG167) in an in vitro plaque reduction assay. After 12 passages, a second variant containing these hemagglutinin mutations and a Lys substitution for the conserved Arg292 of the neuraminidase was isolated. The mutant neuraminidase enzyme exhibited high-level (30,000-fold) resistance to GS 4071, but only moderate (30-fold) resistance to zanamivir and 4-amino-Neu5Ac2en, the amino analog of zanamivir. The mutant enzyme had weaker affinity for the fluorogenic substrate 2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid and lower enzymatic activity compared to the wild-type enzyme. The viral variant containing the mutant neuraminidase did not replicate as well as the wild-type virus in culture and was 10,000-fold less infectious than the wild-type virus in a mouse model. These results suggest that although the R292K neuraminidase mutation confers high-level resistance to GS 4071 in vitro, its effect on viral virulence is likely to render this mutation of limited clinical significance.

Acetamides↗
PubMed1998

Oral administration of a prodrug of the influenza virus neuraminidase inhibitor GS 4071 protects mice and ferrets against influenza infection.

We have recently described GS 4071, a carbocyclic transition-state analog inhibitor of the influenza virus neuraminidase, which has potent inhibitory activity comparable to that of 4-guanidino-Neu5Ac2en (GG167; zanamivir) when tested against influenza A virus replication and neuraminidase activity in vitro. We now report that GS 4071 is active against several strains of influenza A and B viruses in vitro and that oral GS 4104, an ethyl ester prodrug which is converted to GS 4071 in vivo, is active in the mouse and ferret models of influenza virus infection. Oral administration of 10 mg of GS 4104 per kg of body weight per day caused a 100-fold reduction in lung homogenate viral titers and enhanced survival in mice infected with influenza A or B viruses. In ferrets, a 25-mg/kg dose of GS 4104 given twice daily reduced peak viral titers in nasal washings and eliminated constitutional responses to influenza virus infection including fever, increased nasal signs (sneezing, nasal discharge, mouth breathing), and decreased activity. Consistent with our demonstration that the parent compound is highly specific for influenza virus neuraminidases, no significant drug-related toxicity was observed after the administration of oral dosages of GS 4104 of up to 800 mg/kg/day for 14 days in nonclinical toxicology studies with rats. These results indicate that GS 4104 is a novel, orally active antiviral agent with the potential to be used for the prophylaxis and treatment of influenza A and B virus infections.

Acetamides↗
PubMed1998

Identification of GS 4104 as an orally bioavailable prodrug of the influenza virus neuraminidase inhibitor GS 4071.

GS 4071 is a potent carbocyclic transition-state analog inhibitor of influenza virus neuraminidase with activity against both influenza A and B viruses in vitro. GS 4116, the guanidino analog of GS 4071, is a 10-fold more potent inhibitor of influenza virus replication in tissue culture than GS 4071. In this study we determined the oral bioavailabilities of GS 4071, GS 4116, and their respective ethyl ester prodrugs in rats. Both parent compounds and the prodrug of the guanidino analog exhibited poor oral bioavailability (2 to 4%) and low peak concentrations in plasma (Cmaxs; Cmax <0.06 microg/ml). In contrast, GS 4104, the ethyl ester prodrug of GS 4071, exhibited good oral bioavailability (35%) as GS 4071 and high Cmaxs of GS 4071 (Cmax = 0.47 microg/ml) which are 150 times the concentration necessary to inhibit influenza virus neuraminidase activity by 90%. The bioavailability of GS 4104 as GS 4071 was also determined in mice (30%), ferrets (11%), and dogs (73%). The plasma of all four species exhibited high, sustained concentrations of GS 4071 such that at 12 h postdosing the concentrations of GS 4071 in plasma exceeded those necessary to inhibit influenza virus neuraminidase activity by 90%. These results demonstrate that GS 4104 is an orally bioavailable prodrug of GS 4071 in animals and that it has the potential to be an oral agent for the prevention and treatment of influenza A and B virus infections in humans.

Acetamides↗