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P E Kristjansen

Publications and source records attributed to P E Kristjansen.

At least 19 recordsLinked to original sources
PubMed2002

Overexpression of thrombospondin-1 reduces growth and vascular index but not perfusion in glioblastoma.

Little is known about the effects of antiangiogenic therapy on perfusion of human tumors and the mechanisms by which tumors can adapt to these treatments and recur. Here, we examined the effects of serial passaging of LN-229 human glioma xenografts overexpressing thrombospondin (TSP)-1 on tumor growth, vascularity, and perfusion. Persistence of TSP-1 overexpression was confirmed after three serial s.c. passages of small xenografted tumor blocks of cells stably transfected with TSP-1 cDNA (clones C9 and E7) or vector controls (pooled clones A7-A9) in immunodeficient nu/nu mice. The tumor vascularity was estimated by noninvasive near infrared spectroscopy measuring blood volume at 800 +/- 10 nm and by histological vessel scores in CD31-immunostained cryosections. The tumor perfusion was assessed by noninvasive laser Doppler flowmetry. Overexpression of TSP-1 significantly inhibited tumor growth. In size-matched tumors (approximately 300 mm(3)), the blood volume and the histological vessel scores were lower in the TSP-1-transfected tumors than in controls, and this effect was more pronounced in tumors derived from the clone with the highest TSP-1 expression (clone E9). Despite this clear reduction in tumor vascularity, the tumor perfusion was the same in TSP-1-transfected tumors and controls. This study shows that TSP-1 overexpression slows glioma growth in vivo but does not prevent it from reaching a large size (300 mm(3)). Whereas a clear reduction in blood volume during tumor growth and a reduced vascular index at sacrifice are observed in TSP-1-transfected tumors, this did not affect perfusion when size-matched comparisons were performed. Given the increased time needed to reach equal size, it indicates that a fixed rate of perfusion must be maintained in the tumor to allow for growth. Elucidation of the mechanisms that allow this to happen has important consequences for the understanding of tumor recurrence after antiangiogenic therapy.

Animals↗
PubMed2001

Quantitative estimates of angiogenic and anti-angiogenic activity by laser Doppler flowmetry (LDF) and near infra-red spectroscopy (NIRS).

The use of laser Doppler flowmetry (LDF) and near-infra-red spectroscopy (NIRS) for non-invasive in vivo measurements of angiogenic and anti-angiogenic activity in nude mice was evaluated. Angiogenic foci were induced in the skin by implantation of slow release pellets containing 200 ng basic fibroblast growth factor (bFGF). LDF and NIRS recordings from induced foci were significantly higher than placebo implants (P<0.05) and controls (P<0.001), proving that LDF and NIRS provide measures of angiogenic activity. Correspondingly, by these methods, an anti-angiogenic activity was significantly demonstrated in bFGF-stimulated animals treated with either the specific anti-angiogenic compound TNP-470 (P<0.05) or the anti-inflammatory agent dexamethasone (P<0.001). We conclude that LDF and NIRS, alone or in combination, are useful non-invasive tools for early evaluation of angiogenic and anti-angiogenic activity in vivo.

Animals↗
PubMed2000

Therapeutic synergy of TNP-470 and ionizing radiation: effects on tumor growth, vessel morphology, and angiogenesis in human glioblastoma multiforme xenografts.

We examined the effect on tumor growth, vessel morphology, and expression of angiogenic factors of combining radiotherapy and antiangiogenesis in the human glioblastoma line U87 grown in the flank or intracranially in the nude mouse. The antiangiogenic agent TNP-470 was given 6.7 mg/kg s.c. daily on day 1-7 starting 1 week after transplantation. Irradiation (IR), 10 Gy x 1, was administered on day 7. A series of tumors were excised 8 and 48 h after the end of treatment. The vascular morphology was evaluated in CD31 immunostained cryosections and by electron microscopy, and the pattern of expression of angiogenic factors (mRNA and protein) was quantitatively analyzed by phosphorimaging of Northern blots and Western blots. Significant inhibition of s.c. flank tumor growth relative to untreated controls was achieved by monotherapy with both TNP-470 (P < 0.001) and IR (P < 0.001). A significant enhancement of this effect was obtained by combining TNP-470 and IR (P < 0.05). We saw no effect of TNP-470 either alone or in addition to the effect of IR on the survival of mice with intracranial tumors. CD31 immunostaining of s.c. tumors showed acute endothelial swelling and luminal protrusion in irradiated tumor vessels but never in tumors pretreated with TNP-470, and not in the untreated controls. The vessel density (Chalkley point counts) was unchanged by TNP-470 therapy. In the TNP-470-treated tumors, we observed a distinct broadening of the endothelial basement membrane by an approximately 400-700-nm-thick electron-dense yet uncharacterized fibrillar material. TNP-470 treated tumors +/- IR also had a significantly increased mRNA expression of angiopoietin-1, whereas angiopoietin-2, vascular endothelial growth factor and basic fibroblast growth factor mRNA were unchanged by the treatments. In conclusion, TNP-470 significantly enhanced the tumor effect of ionizing IR, and our findings strongly indicate that acute microvascular damage after IR is effectively prevented by concurrent TNP-470 treatment. A significant up-regulation of angiopoietin-1 seems to play a role in this protective mechanism, which as yet is not fully elucidated.

Angiogenesis Inhibitors↗
PubMed2000

Relationship between vessel density and expression of vascular endothelial growth factor and basic fibroblast growth factor in small cell lung cancer in vivo and in vitro.

In 21 human small cell lung cancer (SCLC) cell lines, we determined the expression of mRNA and secreted protein levels of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF). The VEGF expression was highly variable between cell lines, with a > 100-fold variation, under identical in vitro conditions. The bFGF expression in cell lines was generally very low. Nine of the cell lines were further analyzed during growth as solid tumor xenografts in nude mice (in vivo). A more uniform VEGF protein expression was present in vivo. Compared with the variable in vitro expression, VEGF was relatively up-regulated in the tumor lines CPH 54A and CPH 54B and down-regulated in GLC 3. One line, DMS 79, had a high VEGF expression in vivo as well as in vitro. The vessel density was determined by Chalkley point counting on CD31 immunostained cryosections of tumors of each of the nine SCLC lines. We found a strong positive correlation between vessel density and tissue VEGF protein expression (r(s) = 0.75; P = 0.02) and a comparatively strong negative correlation (r(s) = -0.80; P = 0.01) between vessel density and tissue bFGF expression. No significant correlation was present between vessel density and in vitro VEGF expression. We conclude that VEGF and bFGF expression is dependent on microenvironmental conditions, as well as cell line-specific factors, and that a strong positive correlation exists between in vivo VEGF expression and vessel density, whereas high tissue levels of bFGF are not correlated with higher vessel densities in SCLC xenografts.

Animals↗
PubMed1999

Prophylactic cranial irradiation for patients with small-cell lung cancer in complete remission. Prophylactic Cranial Irradiation Overview Collaborative Group.

BACKGROUND: Prophylactic cranial irradiation reduces the incidence of brain metastasis in patients with small-cell lung cancer. Whether this treatment, when given to patients in complete remission, improves survival is not known. We performed a meta-analysis to determine whether prophylactic cranial irradiation prolongs survival. METHODS: We analyzed individual data on 987 patients with small-cell lung cancer in complete remission who took part in seven trials that compared prophylactic cranial irradiation with no prophylactic cranial irradiation. The main end point was survival. RESULTS: The relative risk of death in the treatment group as compared with the control group was 0.84 (95 percent confidence interval, 0.73 to 0.97; P= 0.01), which corresponds to a 5.4 percent increase in the rate of survival at three years (15.3 percent in the control group vs. 20.7 percent in the treatment group). Prophylactic cranial irradiation also increased the rate of disease-free survival (relative risk of recurrence or death, 0.75; 95 percent confidence interval, 0.65 to 0.86; P<0.001) and decreased the cumulative incidence of brain metastasis (relative risk, 0.46; 95 percent confidence interval, 0.38 to 0.57; P<0.001). Larger doses of radiation led to greater decreases in the risk of brain metastasis, according to an analysis of four total doses (8 Gy, 24 to 25 Gy, 30 Gy, and 36 to 40 Gy) (P for trend=0.02), but the effect on survival did not differ significantly according to the dose. We also identified a trend (P=0.01) toward a decrease in the risk of brain metastasis with earlier administration of cranial irradiation after the initiation of induction chemotherapy. CONCLUSIONS: Prophylactic cranial irradiation improves both overall survival and disease-free survival among patients with small-cell lung cancer in complete remission.

Adult↗
PubMed1999

Treatment of newly diagnosed glioblastoma multiforme with carmustine, cisplatin and etoposide followed by radiotherapy. A phase II study.

A meta-analysis and several studies of patients with grade III and IV gliomas have indicated that the addition of nitrosurea based chemotherapy to surgery and radiation may improve survival. We performed a phase II study of pre-irradiative chemotherapy with BCNU, cisplatin and etoposide. This implies a short total treatment duration and a reliable response evaluation. The treatment schedule was three cycles of BCNU 200 mg/m2 i.v. on day 1, cisplatin 20 mg/m2 i.v. on day 1-5 and etoposide (VP-16) 100 mg/m2 i.v. on day 1-5, given every five weeks and followed by localized radiation, 60 Gy in 30 fractions. Twenty-nine patients with newly diagnosed glioblastoma multiforme (GBM), mean age 50 (27-66) and performance status (PS) 0-2 were included. Using the Macdonald criteria 33% had partial remission (PR), 41% stable disease (SD) and 26% progressive disease (PD) after chemotherapy. After additional radiation 44% had PR, 37% SD and 19% PD. Non-hematological toxicity and leukopenia was mild, but thrombocytopenia (TP) frequent. Grade III and IV TP occurred in 25% and 57% respectively, and grade III bleeding in 45%. No severe or fatal complications was seen. Median time to progression (TTP) was 7.6 months (6.0-9.1) and median survival was 11.4 months (10.1-12.7). We conclude that this regimen is effective and feasible in patients with GBM. The short course pre-irradiatory chemotherapy may be less cumbersome than adjuvant chemotherapy and the regimen may be even more active in grade III gliomas.

Adult↗
PubMed1999

The rat Subcutaneous Air Sac model: a quantitative assay of antiangiogenesis in induced vessels.

A new in vivo experimental model--the Subcutaneous Air Sac (SAS) model-has recently been presented to replace a previous in vivo rabbit cornea assay where neovascularisation was induced by chemical injury of the cornea or by implantation of tumour cells intracorneally, a methodology which is believed to cause severe pain to the animals. In the SAS model, an air sac is induced by injection of air subcutaneously on the back of the animal. After 10-14 days the air sac appears as an almost transparent avascular membrane in which induction of new vessels can be studied. We present recent developments of this technique: In the SAS-tumour technique, vascular endothelial growth factor-producing tumour cells are inoculated subcutaneously directly on the membrane, and the formation of new vessels is measured 8 days later. In the SAS-pellet technique, slow-release pellets containing angiogenic factors, basic fibroblast growth factor or vascular endothelial growth factor are implanted on the subcutaneous membrane by a simple operation. The formation of new vessels is measured 10 days later. The ability of the SAS-tumour- and SAS-pellet techniques to detect an antiangiogenic effect of a systemically administered compound was investigated using the fumagillin analogue TNP-470 (o-chloroacetyl-carbamoyl)-fumagillol) as a positive control given subcutaneously for 7 and 9 days, respectively. At a dose of 10 mg TNP-470/kg/day the angiogenesis was reduced by approximately 70% in the SAS-tumour technique and by 40-60% in the SAS-pellet technique. The animals were unaffected by the SAS methodology. The SAS-tumour and SAS-pellet models are considered complementary and make use of simple and almost similar techniques which facilitate the evaluation.

Air Sacs↗
PubMed1998

Effect of radiation therapy on small-cell lung cancer is reduced by ubiquinone intake.

The effect of oral ubiquinone (Q10) intake on the in vivo response of tumors to single dose radiotherapy was examined. The human small-cell lung cancer (SCLC) line CPH 054A, which is sensitive to relatively low doses of X-radiation, was grown as subcutaneous transplants in the flanks of nude nu/nu mice. When macroscopical growth was established, groups of mice received either 10, 20 or 40 mg/kg Q10 in 30 mL soy oil intragastrically daily on 4 consecutive days. Controls received either 30 mL of pure soy oil or nothing. Three h after the last dose half of the tumors in each group received a single radiation dose of 5 Gy, using a 300 kV therapeutic unit. The macroscopic growth pre- and posttreatment was analyzed according to a transformed Gompertz algorithm using the software program GROWTH. Treatment with Q10 or soy oil alone had no effect on tumor growth compared with untreated controls. Groups of tumors that received Q10 and radiotherapy had a significantly lower specific growth delay (SGD) than the radiotherapy-only groups. This effect was significant at 40 mg/kg and borderline at 20 mg/kg, whereas at 10 mg/kg no radioprotection was seen. We conclude that systemic Q10 reduces the response to single dose tumor irradiation inxenotransplanted human SCLC tumors.

Animals↗
PubMed1998

Tumor angiogenesis--a new therapeutic target in gliomas.

Tumor growth is critically dependent on angiogenesis, which is sprouting of new vessels from pre-existing vasculature. This process is regulated by inducers and inhibitors released from tumor cells, endothelial cells, and macrophages. Brain tumors, especially glioblastoma multiforme, have significant angiogenic activity primarily by the expression of the angiogenic factor VEGF Anti-angiogenic therapy represents a new promising therapeutic modality in solid tumors. Several agents are currently under evaluation in clinical trials. The present review describes the principal inducers and inhibitors of angiogenesis in tumors and summarizes what is known about their mechanisms of action in relation to CNS tumors. Potential areas for clinical use are also discussed.

Brain Neoplasms↗
PubMed1996

Superiority of cisplatin or carboplatin in combination with teniposide and vincristine in the induction chemotherapy of small-cell lung cancer. A randomized trial with 5 years follow up.

PURPOSE: The introduction of platinum compounds and epipodophyllotoxins in combination with vincristine as induction chemotherapy in small-cell lung cancer (SCLC) was investigated in order to: (1) compare the efficacy of cisplatin with that of carboplatin in combination with teniposide and vincristine as inducers of remission over three cycles; (2) compare the toxicity pattern of carboplatin and of cisplatin when given in combination regimens; and (3) compare a chemotherapeutic regimen consisting of three alternating combinations with that of regimens consisting of four alternating combinations. PATIENTS AND METHODS: From November 1985 to September 1991, 484 consecutive, previously untreated patients with SCLC, performance status 0-4, entered a three armed randomized trial with three cycles of cisplatin (arm I) or carboplatin (arm II) in combination with teniposide and vincristine alternating with three treatment blocks of cyclophosphamide, etoposide, lomustine and vincristine (block A), doxorubicin and vincristine (block B) and cisplatin, hexamethylmelamine and vindesine (block C) versus alternating treatment with block A, B and C (arm III). RESULTS: No difference in efficacy or toxicity was found between cisplatin and carboplatin at the present dosages. Induction chemotherapy with teniposide plus cisplatin or carboplatin did not result in higher complete response rates (objective response rates 63%, 72% and 65%, respectively) or in significantly greater toxicity, but overall survival was superior compared with the arm III (log-rank test, P = 0.02). The median survival difference was 7 weeks, and two year survival 15% versus 9%. The Cox regression analysis identified the arm III, poor performance status and elevated LDH as factors with statistically significant negative impact on survival. CONCLUSION: Cisplatin and carboplatin produced similar response and survival rates and similar toxicity. Induction with platinum and epipodophyllotoxins did not improve objective response rates, but significantly improved survival without increasing the toxicity.

Adult↗
PubMed1996

Intratumor pharmacokinetics, flow resistance, and metabolism during gemcitabine infusion in ex vivo perfused human small cell lung cancer.

The relationship between tumor physiology and the pharmacokinetics of 2',2' difluorodeoxycytidine [gemcitabine (dFdC)] in ex vivo perfused human small cell lung cancer was examined. Two small cell lung cancer sublines, 54A and 54B, with known in vivo sensitivity to dFdC, were grown as tissue-isolated tumors in athymic mice and perfused ex vivo with or without 20-40 micrometer dFdC. Arteriovenous differences in gases, pH, and metabolites were determined before and during drug infusion. The geometric flow resistance (FR) of individual tumors was calculated, and dFdC and its inactive metabolite 2',2' difluorodeoxyuridine were determined by high-performance liquid chromatography of consecutive samples from the output line. Both tumors had prominent lactate production concurrent with a significant O2 consumption. The arteriovenous pH drop was approximately 0.3 in both tumor lines. Significant metabolic differences between 54A and 54B tumors were found that elucidated previously described differences further. Pharmacokinetic analysis showed that the initial tumor uptake of dFdC was flow limited, and a significant inverse correlation between the geometric FR and initial drug uptake was found. The rate constant for recovery of the drug in the tumor outflow was greater in 54B tumors (P < 0.05), and the geometric FR was greater in 54A tumors (P < 0.01). The drug conversion rate was independent of physiological parameters. Attempts to modify the delivery of dFdC should be directed at the tumor blood flow distribution. More generally, our experimental model provides useful new insight into metabolism and intratumor pharmacokinetics of chemotherapeutic agents in solid tumors.

Animals↗
PubMed1995

Growth inhibition in response to estrogen withdrawal and tamoxifen therapy of human breast cancer xenografts evaluated by in vivo 31P magnetic resonance spectroscopy, creatine kinase activity, and apoptotic index.

Estrogen withdrawal versus tamoxifen (TAM) treatment was compared in two human breast cancer xenografts, the estrogen-dependent ZR75-1 and its estrogen-independent subline ZR75/LCC-3. The following parameters were determined: tumor growth, NTP:P(i) by 31P magnetic resonance spectroscopy, apoptotic index, and creatine kinase (CK) activity. Tumors of each line were grown in ovariectomized nude mice during stimulation from a s.c. 17 beta-estradiol pellet. At a tumor size of approximately 350 mm3, the pellet was removed from one-half of the animals. The remaining one-half served as controls. In parallel experiments, injections of TAM were initiated instead of estrogen withdrawal. Estrogen withdrawal as well as TAM induced growth inhibition of ZR75-1 tumors, whereas ZR75/LCC-3 was resistant to both types of therapy. Growth inhibition of ZR75-1 by estrogen withdrawal, but not by TAM, was accompanied by an 80% increase of the NTP:P(i) ratio (P < 0.01) and a significantly decreased cytosolic CK activity (P < 0.01). No significant change in pH was observed. These changes seemed not to be related to changes in apoptotic index. None of the described changes occurred in ZR75/LCC-3. The present data indicate: (a) ZR75-1 and ZR75/LCC-3 xenografts respond differently to estrogen withdrawal and TAM with regard to growth inhibition, 31P magnetic resonance spectroscopy, and CK activity; (b) estrogen withdrawal, but not TAM, induced a decrease in the CK activity of estrogen-dependent tumor tissue, and (c) increased apoptosis did not explain the growth inhibition and the increase in NTP:P(i) induced by estrogen withdrawal. The results indicate other growth inhibitory mechanisms of TAM in addition to competitive inhibition of the estrogen receptor.

Animals↗
PubMed1995

Effect of estrogen withdrawal on energy-rich phosphates and prediction of estrogen dependence monitored by in vivo 31P magnetic resonance spectroscopy of four human breast cancer xenografts.

The effect of estrogen withdrawal on energy metabolism was studied in four human breast cancer xenografts: the estrogen-dependent MCF-7 and ZR75-1 and the estrogen-independent ZR75/LCC-3 and MDA-MB-231. The tumors were grown in ovariectomized nude mice with a s.c. implanted estrogen pellet. After Gompertzian growth was verified, the estrogen pellet was removed from half of the animals. In vivo 31P magnetic resonance spectroscopy of the tumors was performed 1 day before and on days 2, 6, and 14 after estrogen removal. Estrogen withdrawal induced a significant increase in the nucleoside triphosphate:Pi ratio in the two estrogen-dependent xenografts, whereas this ratio remained unchanged in the estrogen-independent tumors. In ZR75/LCC-3 tumors a slight decrease in nucleoside triphosphate:Pi was observed following onset of estrogen stimulation after initial growth without estrogen. Extracts of freeze-clamped tumors prepared 14 days after estrogen removal were analyzed for ATP and phosphocreatine content. Our findings suggest a correlation between estrogen withdrawal and the steady-state concentrations of ATP, phosphocreatine, and Pi in human breast cancer xenografts. Discrimination analysis of the pretherapeutic spectra enabled us to identify the tumor line and the estrogen dependence of the tumors in 80-90% of all cases.

Animals↗
PubMed1995

Prophylactic cranial irradiation in small cell lung cancer--an update.

The role of prophylactic cranial irradiation (PCI) in the management of patients with small cell lung cancer is reviewed, with emphasis on 11 randomised trials. Several interpretive and methodological problems related to PCI investigations are identified, and it is argued that given the current data PCI should be considered as an optional treatment component in CR patients, that these authors do not recommend, while other investigators do.

Brain Neoplasms↗
PubMed1994

Spatial heterogeneity in tumor perfusion measured with functional computed tomography at 0.05 microliter resolution.

High speed (200 ms temporal resolution) functional computed tomography was used to demonstrate tumor vascular heterogeneity with 0.05 microliter spatial resolution. Vascular topologies were investigated in 2 human small cell lung cancer lines implanted either s.c. or as a tissue isolated preparation in immunocompromised mice. Peripheral versus central vascular topology was identified in the s.c. and tissue-isolated preparations, respectively. Pharmacokinetic analysis demonstrated that tumor physiology was influenced by cell line (P = 0.016) and not by location (P > 0.6). This new technique has the potential to characterize individual tumors in patients with minimal invasiveness, permitting more detailed prognosis and management.

Animals↗