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T O'Reilly

Publications and source records attributed to T O'Reilly.

At least 19 recordsLinked to original sources
PubMed2007

Systemic inflammation alters the inflammatory response in experimental lipopolysaccharide-induced meningitis.

Experiments to evaluate the effect of the level and duration of endotoxaemia on the meningeal inflammatory response were performed in order to determine if systemic inflammation alters meningitis. Rabbits received either saline or Escherichia coli O111:B4 lipopolysacharide (LPS) intravenously at various doses (1, 3 or 10 microg) and times (-8, -2 or 0 h) before an intracisternal injection of 20 ng LPS. An intracisternal LPS injection together with saline intravenously produced a peak cerebrospinal fluid (CSF) tumour necrosis factor (TNF) level (95 +/- 26 ng/ml) at 2 h and peak leucocyte level (5413 +/- 764 cells/microl) at 4 h post-injection. Blood leucocytes were slightly elevated (12 000 +/- 500/microl at 0 h; 16 900 +/- 280/microl at 8 h) but plasma TNF was always undetectable (< 0.05 ng/ml). Conversely, intravenous injection of 3 or 10 microg LPS 2 h prior to intracisternal LPS injection impaired pleocytosis (peak < 220 cells/microl) and delayed ( approximately 4 h) and reduced peak CSF TNF levels (3 microg LPS 5.0 +/- 1.2 ng/ml; 10 microg LPS 6.9 +/- 1.9; P < 0.05). Intravenous administration of 1 microg LPS was less inhibitory to CSF inflammation, but delayed onset (peak 1100 +/- 60 leucocytes/microl CSF at 8 h; 6.3 +/- 0.3 ng TNF/ml CSF at 4 h; both P < 0.05). Neutropenia nadirs were dependent on LPS dose (1 microg, 4500 +/- 1700; 3 microg, 1900 +/- 60; 10 microg, 1100 +/- 100 all at 4 h post-intravenous dose). Peak plasma TNF levels were not dose-dependent (> 8 ng/ml), but plasma TNF was always detectable (> 0.2 ng/ml at 10 h post-intravenous dose). Intravenous LPS administration at 0 h also blocked pleocytosis, but the inhibitory effect was lost when administration at -8 h. In conclusion, the degree and duration of endotoxaemia affect the meningeal inflammatory response to LPS in experimental meningitis.

Animals↗
PubMed2004

Patupilone (epothilone B, EPO906) and imatinib (STI571, Glivec) in combination display enhanced antitumour activity in vivo against experimental rat C6 glioma.

PURPOSE: The microtubule-stabilizing agent patupilone (epothilone B, EPO906) and the tyrosine kinase inhibitor imatinib (STI571, Glivec) which primarily inhibits Bcr-Abl, PDGF and c-Kit tyrosine kinase receptors, were combined in vivo to determine if any interaction would occur with respect to antitumour effect and tolerability using rat C6 glioma xenografted into nude mice. METHODS: Patupilone and imatinib were administered alone or in combination at suboptimal doses. Imatinib treatment (orally once daily) was initiated 4 days after s.c. injection of rat C6 glioma cells into athymic nude mice and patupilone administration (i.v. once per week) was started 3 or 4 days after imatinib treatment. RESULTS: As a single agent, imatinib was inactive in the regimens selected (100 mg/kg: T/C 86% and 116%; 200 mg/kg: T/C 68% and 84%; two independent experiments), but well tolerated (gain in body weight and no mortalities). Patupilone weekly monotherapy demonstrated dose-dependent antitumour effects (1 mg/kg: T/C 67% and 70%; 2 mg/kg: T/C 32% and 63%; 4 mg/kg: T/C 3% and 46%). As expected, dose-dependent body weight losses occurred (final body weight changes at 1 mg/kg were -7% and -3%; at 2 mg/kg were -23% and -13%; and at 4 mg/kg were -33% and -15%). Combining 2 mg/kg patupilone and 200 mg/kg per day imatinib in one experiment produced a non-statistically significant trend for an improved antitumour effect over patupilone alone (combination, T/C 9%), while in the second experiment, enhancement was seen with the combination and reached statistical significance versus patupilone alone (combination, T/C 22%; P=0.008). Reduction of the imatinib dose to 100 mg/kg per day resulted in no enhancement of antitumour activity in combination with 2 mg/kg patupilone. Reduction of the patupilone dose to 1 mg/kg resulted in a reduced antitumour effect, and only a trend for synergy with either imatinib dose (combination, T/C 46% and 40%). Pooling the data from the two experiments confirmed a significant synergy for the combination of 2 mg/kg patupilone and 200 mg/kg per day imatinib (P=0.032), and a trend for synergy at the 1 mg/kg patupilone dose. Reduction in the imatinib dose to 100 mg/kg per day resulted only in additivity with either dose of patupilone. Body weight losses were dominated by the effect of patupilone, since no greater body weight loss was observed in the combination groups. CONCLUSION: Combining patupilone with high-dose imatinib produced an increased antitumour effect without affecting the tolerability of treatment in a relatively chemoresistant rat C6 glioma model. Such results indicate that further evaluation is warranted, in particular to elucidate possible mechanisms of combined action.

Animals↗
PubMed2003

A novel vascular endothelial growth factor-directed therapy that selectively activates cytotoxic prodrugs.

We have generated fusion proteins between vascular endothelial growth factor (VEGF) and the bacterial enzyme carboxypeptidase G2 (CPG2) that can activate the prodrug 4-[(2-chloroethyl)(2-mesyloxyethyl)amino]benzoyl-L-glutamic acid (CMDA). Three asparagine residues of CPG2 were mutated to glutamine (CPG2(Q)3) to prevent glycosylation during secretion, and truncations of VEGF(165) were fused to either the C- or N-terminal of CPG2. The K(m) of the fusion proteins (37.5 microM) was similar to that of secreted CPG2(Q)3 (29.5 microM) but greater than that of wild-type CPG2 (8 microM). The affinity of the fusion proteins for VEGF receptor-2 (VEGFR2) (K(d)=0.5-1.1 nM) was similar to that of [(125)I]VEGF (K(d)=0.5 nM) (ELISA) or slightly higher (K(d)=1.3-9.6 nM) (competitive RIA). One protein, VEGF(115)-CPG2(Q)3-H(6), possessed 140% of the enzymic activity of secreted CPG2(Q)3, and had a faster half-maximal binding time for VEGFR2 (77 s), than the other candidates (330 s). In vitro, VEGF(115)-CPG2(Q)3-H(6) targeted CMDA cytotoxicity only towards VEGFR-expressing cells. The plasma half-life of VEGF(115)-CPG2(Q)3-H(6) in vivo was 3 h, comparable to equivalent values observed in ADEPT. We conclude that enzyme prodrug therapy using VEGF as a targeting moiety represents a promising novel antitumour therapy, with VEGF(115)-CPG2(Q)3-H(6) being a lead candidate.

Adenocarcinoma↗
PubMed2002

A rat model of bone cancer pain.

This study describes the first known model of bone cancer pain in the rat. Sprague-Dawley rats receiving intra-tibial injections of syngeneic MRMT-1 rat mammary gland carcinoma cells developed behavioural signs indicative of pain, including: mechanical allodynia, difference of weight bearing between hind paws and mechanical hyperalgesia. The development of the bone tumour and structural damage to the bone was monitored by radiological analysis, quantitative measurement of mineral content and histology. Intra-tibial injections of 3 x 10(3) or 3 x 10(4) syngeneic MRMT-1 cells produced a rapidly expanding tumour within the boundaries of the tibia, causing severe remodelling of the bone. Radiographs showed extensive damage to the cortical bone and the trabeculae by day 10-14 after inoculation of 3 x 10(3) MRMT-1 cells, and by day 20, the damage was threatening the integrity of the tibial bone. While both mineral content and mineral density decreased significantly in the cancerous bone, osteoclast numbers in the peritumoural compact bone remained unchanged. However, tartarate-resistant acid phosphatase staining revealed a large number of polykariotic cells, resembling those of osteoclasts within the tumour. No tumour growth was observed after the injection of heat-killed MRMT-1 cells. Intra-tibial injections of 3 x 10(3) or 3 x 10(4) MRMT-1 cells, heat-killed cells or vehicle did not show changes in body weight and core temperature over 19-20 days. The general activity of animals after injection with live or heat-killed MRMT-1 cells was higher than that of the control group, however, the activity of the MRMT-1 treated group declined during the progress of the disease. Rats receiving intra-tibial injections of MRMT-1 cells displayed the gradual development of mechanical allodynia and mechanical hyperalgesia/reduced weight bearing on the affected limb, beginning on day 12-14 or 10-12 following injection of 3 x 10(3) or 3 x 10(4) cells, respectively. These symptoms were not observed in rats receiving heat-killed cells or vehicle. Behavioural data suggest a reasonable time window for evaluation of anti-nociceptive agents between day 14 and 20 after cancer cell inoculation in this model. Acute treatment with morphine (1-3mg/kg, subcutanously (s.c.)) produced a dose-dependent reduction in the response frequency of hind paw withdrawal to von Frey filament stimulation 17 or 19 days following intra-tibial injections of 3 x 10(3) MRMT-1 cells. A significant reduction in the difference in hind limb weight bearing was also observed. Acute treatment with celebrex (10-30 mg/kg, s.c.) did not affect mechanical allodynia or difference in weight bearing in rats 20 days following treatment with 3 x 10(3) MRMT-1 cells. Although the pathophysiology of cancer pain is largely unknown, significant enhancement of glial fibrillary acidic protein (GFAP) staining in the corresponding segments of the ipsilateral spinal cord highlights the possible involvement of astrocytes. In summary, the induction of bone cancer in the rat by the syngeneic MRMT-1 mammary tumour cell line provides a valid pre-clinical model for pain associated with bone metastases. Significant mechanical hyperalgesia and allodynia develops in association with the progression of the tumour in the bone marrow cavity, while the general condition of the animal remains satisfactory. While acute treatment with morphine has some analgesic effect on hind limb sparing the selective COX-2 inhibitor, celebrex, has no influence on the pain-related behavioural changes in this model.

Analgesics, Opioid↗
PubMed2002

Pregnant athletes: a summary review of the legal issues.

This summary review is not, and should not be relied upon as, legal advice. It has been prepared at the request of the Journal of Science and Medicine in Sport as a discussion paper for the purposes of providing a background in the legal issues arising from the participation of pregnant women in sport. The discussion is necessarily pitched at a very general level, and without any specific circumstances in mind. Readers with particular concerns, or with specific issues to be addressed, should seek independent legal advice.

Australia↗
PubMed2001

Selective in vivo and in vitro effects of a small molecule inhibitor of cyclin-dependent kinase 4.

BACKGROUND: Cyclin-dependent kinase 4 (Cdk4) represents a prime target for the treatment of cancer because most human cancers are characterized by overexpression of its activating partner cyclin D1, loss of the natural Cdk4-specific inhibitor p16, or mutation(s) in Cdk4's catalytic subunit. All of these can cause deregulated cell growth, resulting in tumor formation. We sought to identify a small molecule that could inhibit the kinase activity of Cdk4 in vitro and to then ascertain the effects of that inhibitor on cell growth and tumor volume in vivo. METHODS: A triaminopyrimidine derivative, CINK4 (a chemical inhibitor of Cdk4), was identified by screening for compounds that could inhibit Cdk4 enzyme activity in vitro. Kinase assays were performed on diverse human Cdks and on other kinases that were expressed in and purified from insect cells to determine the specificity of CINK4. Cell cycle effects of CINK4 on tumor and normal cells were studied by flow cytometry, and changes in phosphorylation of the retinoblastoma protein (pRb), a substrate of Cdk4, were determined by western blotting. The effect of the inhibitor on tumor growth in vivo was studied by use of tumors established through xenografts of HCT116 colon carcinoma cells in mice. Statistical tests were two-sided. RESULTS: CINK4 specifically inhibited Cdk4/cyclin D1 in vitro. It caused growth arrest in tumor cells and in normal cells and prevented pRb phosphorylation. CINK4 treatment resulted in statistically significantly (P: =.031) smaller mean tumor volumes in a mouse xenograft model. CONCLUSIONS: Like p16, the natural inhibitor of Cdk4, CINK4 inhibits Cdk4 activity in vitro and slows tumor growth in vivo. The specificity of CINK4 for Cdk4 raises the possibility that this small molecule or one with a similar structure could have therapeutic value.

Animals↗
PubMed2001

In vivo metabolism of epothilone B in tumor-bearing nude mice: identification of three new epothilone B metabolites by capillary high-pressure liquid chromatography/mass spectrometry/tandem mass spectrometry.

Epothilone B is a 16-membered macrolide produced by the myxobacterium Sorangium cellulosum and is currently under clinical investigation. Experimentally, epothilone B demonstrates potent antiproliferative activity at the nanomolar level in vitro, and potent regression-producing antitumor activity in vivo, similar to paclitaxel (Taxol). In order to foster the design of improved derivatives, the potential biotransformation products of epothilone B formed in liver of tumor-bearing mice after intravenous administration of 10 mg/kg were characterized in an early stage of compound development. Solely on the basis of capillary high-performance liquid chromatography, combined either with electrospray tandem mass spectrometry (in precursor and product ion scan mode) and single analyzing time-of-flight mass spectrometry (H/D exchange and accurate mass measurement), three main metabolites could be detected. The three metabolites, formed by the liver, have in common that the epoxide ring was hydrolyzed and that the macrocyclic lactone ring was opened to the acid. In two cases it is assumed that open-chain intermediates re-cycled either to a lactone or, after conjugation with taurine, to the respective lactam. The proposed structures were additionally supported by the determination of the number of the exchangeable hydrogen atoms and by confirmation of the proposed elemental composition by exact mass measurement.

Animals↗
PubMed2001

Tyrosine kinase inhibitors: from rational design to clinical trials.

Protein kinases play a crucial role in signal transduction as well as in cellular proliferation, differentiation, and various regulatory mechanisms. The inhibition of growth related kinases, especially tyrosine kinases, might provide new therapies for diseases such as cancer. The progress made in the crystallization of protein kinases has confirmed that the ATP-binding domain of tyrosine kinases is an attractive target for drug design. Three successful examples of drug design at Novartis using a tyrosine kinase as a molecular target are described. PKI166, a pyrrolo[2,3,-d]pyrimidine derivative, is a dual inhibitor of both the EGFR and the ErbB2 kinases. The compound entered clinical trials in 1999, based on its favorable preclinical profile: potent inhibition of EGF-mediated signalling in cells, in vivo antitumor activity in several EGFR overexpressing xenograft tumor models in nude mice, long-lasting inhibition of EGF-stimulated EGFR autophosphorylation in tumor tissue, good oral bioavailability in animals, and no prohibitive in vitro and in vivo toxicity findings. The anilino-phthalazine derivative PTK787/ZK222584 (Phase I, co-developed by Schering AG, Berlin) is a potent and selective inhibitor of both the KDR and Flt-1 kinases with interesting anti-angiogenic and pharmacokinetic properties (orally bioavailable). STI571 (Glivec, Gleevec), a phenylamino-pyrimidine derivative, is a potent inhibitor of the Abl tyrosine kinase, which is present in 95% of patients with chronic myelogenous leukemia (CML). The compound specifically inhibits proliferation of v-Abl and Bcr-Abl expressing cells (including cells from CML patients) and shows anti-tumor activity as a single agent in animal models at well-tolerated doses. Pharmacologically relevant concentrations are achieved in the plasma of animals (oral administration). Promising data from phase I and II clinical trials in CML patients (98% haematological response rate in Phase I) support the fact that the STI571 represents a new treatment modality for CML. In addition, potent inhibition of the PDGFR and c-Kit tyrosine kinases also indicates its possible clinical use in solid tumors.

Animals↗
PubMed2001

(99m)Tc-E-selectin binding peptide for imaging acute osteomyelitis in a novel rat model.

INTRODUCTION: In the present study, (99m)Tc-radiolabelled E-selectin binding peptide ((99m)Tc-IMP-178) was investigated for its potential to image acute pyogenic osteomyelitis in a new animal model. Intraindividual comparisons were performed using an irrelevant peptide ((99m)Tc-IMP-100) to demonstrate specificity. METHODS: An acute pyogenic osteomyelitis was induced by injecting 0.05 ml of 5% sodium morrhuate and 5x10(8) CFU of Staphylococcus aureus into the medullary cavity of the right tibia in 16 rats. Sixteen additional rats served as untreated controls. Whole-body imaging of pyogenic (n=4) and untreated (n=4) animals was performed continuously during the first 8 h (12 MBq i.v. of (99m)Tc-IMP-178 and (99m)Tc-IMP-100 for control), and one further single image was acquired after 16 h p.i. Tissue biodistribution studies were performed in 12 rats with an acute pyogenic osteomyelitis and in 12 untreated rats 1, 4 and 24 h after injection. Data of the histological/radiological and haematological investigations were obtained in all animals. RESULTS: Histopathologically, 15 of 16 treated rats (93%) developed an acute pyogenic osteomyelitis showing a major infiltration of the bone marrow by polymorphonuclear leukocytes as well as the formation of sequestra. Haematologically, the number of leukocytes increased by 100%, the lymphocytes by 11% and the granulocytes decreased by 39%. After i.v. injection, (99m)Tc-IMP-178 rapidly cleared from the body resulting in good scintigraphic target-to-background (T/B) ratios. The highest uptake of the tracer in the pyogenic bone was observed at 60 min p.i. (0.43+/-0.02% ID.g-1 for (99m)Tc-IMP-178 and 0.30+/-0.02% ID.g-1 for (99m)Tc-IMP-100), resulting in a higher osteomyelitis-to-healthy collateral ratio with T/B of 2.40+/-0.65 ((99m)Tc-IMP-178) compared with 1.85+/-0.48 ((99m)Tc-IMP-100). No adverse reactions were seen after injection of (99m)Tc-IMP-178. CONCLUSIONS: (99m)Tc-IMP-178 allows imaging of an acute osteomyelitic lesions, presumably by interaction of (99m)Tc-IMP-178 with activated upregulated vascular endothelium.

Acute Disease↗
PubMed2001

Intraoperative sonographic localization of breast masses: success with specimen sonography and surgical bed sonography to confirm excision.

OBJECTIVE: To assess the use of intraoperative sonography for localization of breast masses at excisional biopsy, with specimen and surgical bed sonography to confirm excision. METHODS: A computer search of the 5-year period from January 1993 through January 1998 revealed 138 consecutive women referred for sonographically guided excisional biopsy of 148 masses; 35 masses were excluded because they had no postoperative mammograms. One hundred thirteen masses constituted the study group. Specimen sonography (n = 60) or surgical bed sonography (n = 53) was performed as the initial evaluation to confirm excision, but ultimately, surgical bed sonography may have been necessary after specimen sonography, and specimen sonography may have been necessary after surgical bed sonography. The miss rates determined by postoperative imaging were calculated for each group and compared with those of mammographically guided needle localization series from the literature. RESULTS: Follow-up physical examination and mammography showed no residual mass in the region of surgery in any patient. However, follow-up sonography had 1 miss in the initial specimen sonogram group (1 [1.7%] of 60) and 1 miss in the initial surgical bed group (1 [1.9%] of 53). As shown by the Fisher exact test, there was no significant difference between the miss rates of the 2 initial methods of confirming lesion excision or between the miss rates of these initial methods, both groups combined, and 6 mammographic localization series from the literature. CONCLUSION: Intraoperative breast sonography, using specimen sonography and scanning the surgical bed, has miss rates comparable with those of mammographic needle localization. Follow-up sonography must be performed if there is any doubt of complete excision.

Adult↗
PubMed2000

Intracranial inhibition of platelet-derived growth factor-mediated glioblastoma cell growth by an orally active kinase inhibitor of the 2-phenylaminopyrimidine class.

Glioblastoma multiforme is the most common primary human brain tumor, and it is, for all practical purposes, incurable in adult patients. The high mortality rates reflect the fact that glioblastomas are resistant to adjuvant therapies (radiation and chemicals), the mode of action of which is cytotoxic. We show here that an p.o.-active small molecule kinase inhibitor of the 2-phenylaminopyrimidine class may have therapeutic potential for glioblastomas. STI571 inhibits the growth of U343 and U87 human glioblastoma cells that have been injected into the brains of nude mice, but it does not inhibit intracranial growth of ras-transformed cells. Studies on a broad panel of genetically validated human and animal cell lines show that STI571 acts by disruption of the ligand:receptor autocrine loops for platelet-derived growth factor that are a pervasive feature of malignant astrocytoma. The cellular response of glioblastoma cells to STI571 does not appear to involve an apoptotic mechanism.

3T3 Cells↗
PubMed2000

PTK787/ZK 222584, a novel and potent inhibitor of vascular endothelial growth factor receptor tyrosine kinases, impairs vascular endothelial growth factor-induced responses and tumor growth after oral administration.

PTK787/ZK 222584 (1-[4-chloroanilino]-4-[4-pyridylmethyl] phthalazine succinate) is a potent inhibitor of vascular endothelial growth factor (VEGF) receptor tyrosine kinases, active in the submicromolar range. It also inhibits other class III kinases, such as the platelet-derived growth factor (PDGF) receptor beta tyrosine kinase, c-Kit, and c-Fms, but at higher concentrations. It is not active against kinases from other receptor families, such as epidermal growth factor receptor, fibroblast growth factor receptor-1, c-Met, and Tie-2, or intracellular kinases such as c-Src, c-Abl, and protein kinase C-alpha. PTK787/ZK 222584 inhibits VEGF-induced autophosphorylation of kinase insert domain-containing receptor (KDR), endothelial cell proliferation, migration, and survival in the nanomolar range in cell-based assays. In concentrations up to 1 microM, PTK787/ZK 222584 does not have any cytotoxic or antiproliferative effect on cells that do not express VEGF receptors. After oral dosing (50 mg/kg) to mice, plasma concentrations of PTK787/ZK 222584 remain above 1 microM for more than 8 h. PTK787/ZK 222584 induces dose-dependent inhibition of VEGF and PDGF-induced angiogenesis in a growth factor implant model, as well as a tumor cell-driven angiogenesis model after once-daily oral dosing (25-100 mg/kg). In the same dose range, it also inhibits the growth of several human carcinomas, grown s.c. in nude mice, as well as a murine renal carcinoma and its metastases in a syngeneic, orthotopic model. Histological examination of tumors revealed inhibition of microvessel formation in the interior of the tumor. PTK787/ZK 222584 is very well tolerated and does not impair wound healing. It also does not have any significant effects on circulating blood cells or bone marrow leukocytes as a single agent or impair hematopoetic recovery after concomitant cytotoxic anti-cancer agent challenge. This novel compound has therapeutic potential for the treatment of solid tumors and other diseases where angiogenesis plays an important role.

Angiogenesis Inhibitors↗
PubMed2000

Systemic neutralization of interleukin-8 markedly reduces neutrophilic pleocytosis during experimental lipopolysaccharide-induced meningitis in rabbits.

Interleukin-8 (IL-8) is elevated in the cerebrospinal fluid (CSF) of patients with meningitis and is proposed to participate in subarachnoid-space pleocytosis. However, intracisternal injection of IL-8 into rabbits failed to induce indices typical of meningitis (leukocyte, tumor necrosis factor, or protein accumulation in the CSF or histopathological changes), indicating that merely increasing the CSF level of this chemokine is insufficient to induce inflammation in this anatomical site. IL-8 treatment did not affect inflammatory responses to subsequently intracisternally administered lipopolysaccharide (LPS). IL-8 was chemotactic for rabbit neutrophils in vitro, and subcutaneous injection of IL-8 (diluted in buffer or CSF) proved the in vivo activity of this peptide and suggested the absence of an IL-8 inhibitor in normal rabbit CSF. LPS-dependent pleocytosis was only slightly diminished by intracisternally administered murine anti-rabbit IL-8 monoclonal antibody (MAb) WS-4 but was dramatically reduced by intravenously administered MAb. Therefore, elevated CSF IL-8 levels may contribute to, but cannot solely account for, neutrophil influx into the subarachnoid space during meningitis. However, inhibition of IL-8 activity of the bloodstream side of the blood-brain barrier effectively reduces pleocytosis, indicating a central role of IL-8 in neutrophil influx into CSF during bacterial meningitis. Thus, inhibition of IL-8 is a possible therapeutic target for adjunct treatment of meningitis.

Animals↗
PubMed2000

PKC412--a protein kinase inhibitor with a broad therapeutic potential.

The staurosporine derivative PKC412 was originally identified as an inhibitor of protein kinase C (PKC) and subsequently shown to inhibit other kinases including the kinase insert domain receptor (KDR) (vascular endothelial growth factor receptor, VEGF-R2), the receptor of platelet-derived growth factor, and the receptor for the stem cell factor, c-kit. PKC412 showed a broad antiproliferative activity against various tumor and normal cell lines in vitro, and was able to reverse the Pgp-mediated multidrug resistance of tumor cells in vitro. Exposure of cells to PKC412 resulted in a dose-dependent increase in the G2/M phase of the cell cycle concomitant with increased polyploidy, apoptosis and enhanced sensitivity to ionizing radiation. PKC412 displayed a potent antitumor activity as single agent and was able to potentiate the antitumor activity of some of the clinically used cytotoxins (Taxol and doxorubicin) in vivo. The combined treatment of PKC412 with loco-regional ionizing irradiation showed significant antitumor activity against tumors which are resistant to both ionizing radiation and chemotherapeutic agents (dysfunctional p53). The finding that PKC412 is an inhibitor of the VEGF-mediated cellular signaling via inhibition of KDR and PKC in vitro is consistent with the in vivo inhibition of VEGF-dependent angiogenesis in a growth factor implant model. Orally administered PKC412 also strongly inhibited retinal neovascularization as well as laser-induced choroidal neovascularization in murine models. In summary, PKC412 may suppress tumor growth by inhibiting tumor angiogenesis in addition to directly-inhibiting tumor cell proliferation via its effects on PKC and/or other protein kinases. PKC412 is currently in Phase I clinical trials for treatment of advanced cancer as well as for the treatment of ischemic retinopathy.

Angiogenesis Inhibitors↗
PubMed1998

Unique chemical reactivity of His-21 of CRM-197, a mutated diphtheria toxin.

CRM-197 is a mutated diphtheria toxin (63000 Da) widely used as a carrier protein of conjugated vaccines. Among the 14 histidines of CRM-197, His-21 was found to be modified selectively with iodoacetamide based reagents. This finding suggests a simplified method for the preparation of conjugate vaccines crosslinked to CRM-197. A bifunctional iodoacetamide, N,N'-(2-hydroxy-1,3-propanediyl)-bis-12-iodoacetamidel (I-CH2-CONH-CH2-CH(OH)-CH2-NHCO-CH2-I) (HPBIA), was synthesized and allowed to react with CRM-197. In the alkaline buffer of pH 8.0-8.4, HPBIA was shown to react and intra-bridge His-21 and Lys-24 of CRM-197 sequentially. At lower pH (7.1-7.5) in the phosphate buffer, the reactivity of Lys-24 toward HPBIA was suppressed drastically. Under these conditions, His-21 could be specifically labeled with HPBIA. Initial experiments have demonstrated that HPBIA modified CRM-197 is able to crosslink to a cysteine-containing peptide. These results offer a potential route for improving the homogeneity of CRM-197 based protein-peptide as well as protein-polysaccharide conjugates.

Acetamides↗
PubMed1998

A Comparison of Self-Explanation and Elaborative Interrogation.

The purpose of the present study was to examine the effectiveness of two learning strategies, self-explanation and elaborative interrogation, for the retention of scientific facts. University students (N = 55) were asked to learn facts about the cardiovascular system using one of three approaches. Self-explanation participants were required to explain what the facts meant to them and how they related to their prior knowledge. Elaborative interrogation participants answered "why" the facts made sense. Finally, the control group simply repeated the facts aloud. Self-explanation participants significantly outperformed elaborative interrogation and repetition control participants on measures of cued recall and recognition. Elaborative interrogation was no more effective than repetition. Results were discussed in terms of the practicality and flexibility of each approach. Copyright 1998 Academic Press.

Journal Article↗
PubMed1997

Effect of combination therapy of rifampicin and azithromycin on TNF levels during a rat model of chronic osteomyelitis.

The purpose of the present study was to evaluate the combination of azithromycin and rifampicin on experimental chronic osteomyelitis due to Staphylococcus aureus. Alterations in bone bacterial titre, activity of tumour necrosis factor (TNF), a cytokine implicated in inflammation-induced bone pathology, and histopathological changes during infection and following antibiotic treatment were evaluated. Rats were infected with S. aureus by direct tibial inoculation and then randomized 56 days after infection to receive saline treatment or a combination of azithromycin and rifampicin (50 mg/kg po and 25 mg/kg sc respectively) once daily for 21 days. The combination of azithromycin and rifampicin was successful as determined by dramatic reduction in bone bacterial counts (approximately log 4 cfu), but regrowth of the organisms occurred suggesting that the duration of treatment was insufficient. TNF alpha mRNA and TNF activity were constantly elevated by approximately 20- and >200-fold, respectively, and remained elevated irrespective of antimicrobial treatment. Bone histology revealed extensive increase in bone turnover in both the infected and antibiotic treated bones with no difference being observed between the groups. This suggests that, in infected bone, the elevated TNF levels observed may be directly related to the bone pathology and both remain largely unchanged despite potent antibiotic therapy.

Animals↗