pyrophosphate and Colorectal-Neoplasms

Topics: Adenosine Triphosphate; Colorectal Neoplasms; Diphosphates; DNA Methylation; Glioma; Humans; Isocitrate Dehydrogenase; Janus Kinase 2; Mutation; Myeloproliferative Disorders; Polymorphism, Single Nucleotide; Proto-Oncogene Proteins; Proto-Oncogene Proteins p21(ras); ras Proteins; Sequence Analysis, DNA; Templates, Genetic

Processed meat intake has been associated with increased colorectal cancer risk. We have shown that cured meat promotes carcinogen-induced preneoplastic lesions and increases specific biomarkers in the colon of rats.. We investigated whether cured meat modulates biomarkers of cancer risk in human volunteers and whether specific agents can suppress cured meat-induced preneoplastic lesions in rats and associated biomarkers in rats and humans.. Six additives (calcium carbonate, inulin, rutin, carnosol, α-tocopherol, and trisodium pyrophosphate) were added to cured meat given to groups of rats for 14 d, and fecal biomarkers were measured. On the basis of these results, calcium and tocopherol were kept for the following additional experiments: cured meat, with or without calcium or tocopherol, was given to dimethylhydrazine-initiated rats (47% meat diet for 100 d) and to human volunteers in a crossover study (180 g/d for 4 d). Rat colons were scored for mucin-depleted foci, putative precancer lesions. Biomarkers of nitrosation, lipoperoxidation, and cytotoxicity were measured in the urine and feces of rats and volunteers.. Cured meat increased nitroso compounds and lipoperoxidation in human stools (both P < 0.05). Calcium normalized both biomarkers in rats and human feces, whereas tocopherol only decreased nitro compounds in rats and lipoperoxidation in feces of volunteers (all P < 0.05). Last, calcium and tocopherol reduced the number of mucin-depleted foci per colon in rats compared with nonsupplemented cured meat (P = 0.01).. Data suggest that the addition of calcium carbonate to the diet or α-tocopherol to cured meat may reduce colorectal cancer risk associated with cured-meat intake. This trial was registered at clinicaltrials.gov as NCT00994526.

Topics: Abietanes; Acetylcysteine; Adult; Aged; alpha-Tocopherol; Animals; Biomarkers; Blood Glucose; C-Reactive Protein; Calcium, Dietary; Carcinogenesis; Carcinogens; Cholesterol; Colon; Colorectal Neoplasms; Creatinine; Cross-Over Studies; Dimethylhydrazines; Diphosphates; Feces; Female; Healthy Volunteers; Humans; Inulin; Meat Products; Middle Aged; Rats; Rats, Inbred F344; Rutin; Single-Blind Method; Thiobarbituric Acid Reactive Substances

Tenofovir (TFV; prescribed as TFV disoproxil fumarate and TFV alafenamide prodrugs) is currently used for HIV prevention and treatment. TFV must be phosphorylated twice into TFV-diphosphate (TFV-DP) to become pharmacologically active. Previously, we reported heterogeneity in TFV-DP distribution in colorectal tissue (a putative site of HIV infection) sections collected from research participants receiving a TFV-containing enema. This observed heterogeneity is likely multifactorial. Of note, TFV-DP is structurally similar to ATP. It is known that nucleotidases such as nucleoside triphosphate diphosphohydrolases (NTPDases) dephosphorylate ATP. Thus, it was hypothesized that NTPDase-mediated dephosphorylation plays a role in regulating TFV-DP levels in colorectal tissue. To test this hypothesis, recombinant NTPDase proteins (NTPDase 1, 3, 4, 5, 6, and 8) were incubated, individually, with TFV-DP to determine their abilities to dephosphorylate TFV-DP in vitro. Following incubations, TFV-DP dephosphorylation was determined using both malachite green phosphate assays and ultrahigh-performance liquid chromatography tandem mass spectrometry. From these, NTPDase 1 exhibited the highest activity toward TFV-DP. Further, enzyme kinetic analysis revealed Michaelis-Menten kinetics for NTPDase 1-mediated TFV-DP dephosphorylation. Next, immunoblot analyses were conducted to confirm the expression of NTPDase 1 protein in human colorectal tissue. Liquid chromatography coupled to mass spectrometry proteomics analysis was used to measure the relative abundance of NTPDases in human colorectal tissue among healthy adult individuals (

Topics: Adenosine Triphosphate; Adult; Anti-HIV Agents; Colorectal Neoplasms; Diphosphates; HIV Infections; Humans; Kinetics; Nucleosides; Nucleotides; Tenofovir

Topics: Biomarkers, Tumor; Colorectal Neoplasms; Diphosphates; Humans; Interleukin-23; Neoplasm Proteins; Pentosyltransferases; Poly(ADP-ribose) Polymerases; Ribose

This study explored the applicability of serum level and tissue expression of Ribonucleotide-diphosphate Reductase subunit M2 B (RRM2B) as reliable biomarkers for colorectal cancer (CRC) progression and metastasis.. The present descriptive-analytic cohort study was conducted on 50 newly diagnosed CRC patients (stage II, III) and 50 healthy individuals. The new cases had not received any therapeutic intervention and underwent surgery immediately after the initial diagnosis. Tumorous tissues and marginal healthy tissues (as control) were excised to determine the mRNA tissue expression of RRM2B by Real-Time PCR. Serum RRM2B protein was measured using an ELISA method once in the control group. In the patients, serum RRM2B protein was evaluated before, 1 and 3 months after surgery. The tumor metastasis node (TMN) classification system and liver metastasis were evaluated in CRC patients. The results showed significantly lower RRM2B serum levels in 1 and 3 months after surgery compared with the pre-surgery condition (P = 0.014, P < 0.001 respectively). The mean RRM2B gene expression was 51% lower in tumor tissue than its adjacent normal tissue (P < 0.001). No significant relationship was found between serum level of RRM2B and tumor staging and metastasis in patients before surgery (P = 0.373, P = 0.189), 1 month after surgery (P = 0.960, P = 0.088), and 3 months after surgery (P = 0.407, P = 0.724). RRM2B expression in tumor tissue is not associated with tumor staging and metastasis (P = 0.254, P = 0.721).. These data suggest measuring serum protein level of RRM2B could have a role in CRC progression, although this study should be considered preliminary due to small sample size and short follow-up duration.

Topics: Biomarkers; Biomarkers, Tumor; Cohort Studies; Colorectal Neoplasms; Diphosphates; Humans; Neoplasm Staging; Ribonucleotides

Photoacoustic imaging (PAI) is a novel noninvasive and nonionizing imaging technique that allows longitudinal imaging of tumor vasculature. Two models of colorectal carcinoma (SW1222 and LS174T) that possess differing pathophysiologic vascularization were established as subcutaneous tumors in mice. Monitoring of response was performed over a 16-day "regrowth" period following treatment at 40 mg/kg, and at day 2 for a "dose response" study at 40 mg/kg, 10 mg/kg, 1 mg/kg, and sham dose.. Qualitative and quantitative changes in PA signal are observed, with an initial decrease followed by a plateau and subsequent return of signal indicating regrowth. Both tumor types exhibited a decrease in signal; however, the more vascularized SW1222 tumors show greater response to treatment. Decreasing the dose of OXi4503 led to a decrease in PA signal intensity of 60%, 52%, and 20% in SW1222 tumors and 30%, 26%, and 4% for LS174T tumors.. We have shown for the first time that PAI can observe the pharmacodynamic response of tumor vasculature to drug treatment both longitudinally and at different dose levels. Assessment of differing response to treatment based on vascular pathophysiologic differences among patients has the potential to provide personalized drug therapy; we have demonstrated that PAI, which is clinically translatable, could be a powerful tool for this purpose.

Topics: Animals; Cell Line, Tumor; Colorectal Neoplasms; Diphosphates; Dose-Response Relationship, Drug; Female; Longitudinal Studies; Mice; Mice, Inbred BALB C; Mice, Nude; Molecular Imaging; Neovascularization, Pathologic; Photoacoustic Techniques; Stilbenes; Xenograft Model Antitumor Assays

Understanding the uptake of a drug by diseased tissue, and the drug's subsequent spatiotemporal distribution, are central factors in the development of effective targeted therapies. However, the interaction between the pathophysiology of diseased tissue and individual therapeutic agents can be complex, and can vary across tissue types and across subjects. Here, we show that the combination of mathematical modelling, high-resolution optical imaging of intact and optically cleared tumour tissue from animal models, and in vivo imaging of vascular perfusion predicts the heterogeneous uptake, by large tissue samples, of specific therapeutic agents, as well as their spatiotemporal distribution. In particular, by using murine models of colorectal cancer and glioma, we report and validate predictions of steady-state blood flow and intravascular and interstitial fluid pressure in tumours, of the spatially heterogeneous uptake of chelated gadolinium by tumours, and of the effect of a vascular disrupting agent on tumour vasculature.

Topics: Animals; Antineoplastic Agents; Blood Vessels; Cell Line, Tumor; Colorectal Neoplasms; Contrast Media; Diphosphates; Disease Models, Animal; Female; Gadolinium; Glioma; Humans; Hydrodynamics; Image Processing, Computer-Assisted; Mice; Mice, Inbred C57BL; Mice, Nude; Models, Theoretical; Regional Blood Flow; Stilbenes; Transplantation, Heterologous

Preclinical research indicate that vascular disrupting agent (VDA) treatment induces extensive tumor death but also a systemic mobilization of bone marrow derived cells including endothelial progenitor cells (EPC) leading to revascularization and renewed growth within the residual tumor. This study investigates if combination of VDA with the anti-angiogenic agent Sunitinib increases the treatment efficacy in a colorectal liver metastases mouse model.. CBA mice with established liver metastases were given a single dose of OXi4503 at day 16 post tumor induction, a daily dose of Sunitinib starting at day 14 or day 16 post tumor induction or a combination of Sunitinib given daily from day 14 or day 16 post tumor induction in combination with a single dose of OXi4503 at day 16. Treatment was terminated at day 21 post tumor induction and its effects were assessed using stereological and immunohistochemical techniques. Long term effects were assessed in a survival study.. Combination with long (7 day) Sunitinib treatment lead to liver toxicity but this was ameliorated in the shorter (5 day) treatment without significantly altering the effects on tumor reduction. Combination treatment resulted in significant reduction of viable tumor, reduction in tumor vasculature, reduction in tumor proliferation, increase in tumor apoptosis and prolonged mouse survival compared to control and single arm treatments. Complete tumor eradication was not achieved. Redistribution of E-cadherin and strong up regulation of ZEB1 and Vimentin were observed in the surviving tumor; indicative of epithelial to mesenchymal transition (EMT), a mechanism that could contribute to tumor resistance.. Combination treatment significantly reduces viable tumor and prolongs animal survival. EMT in the surviving tumor may prevent total tumor eradication and could provide novel targets for a more lasting treatment.

Topics: Angiogenesis Inhibitors; Animals; Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cadherins; Chemical and Drug Induced Liver Injury; Colorectal Neoplasms; Diphosphates; Epithelial-Mesenchymal Transition; Humans; Indoles; Liver Neoplasms; Male; Mice; Mice, Inbred CBA; Protein Kinase Inhibitors; Pyrroles; Stilbenes; Sunitinib; Vimentin; Xenograft Model Antitumor Assays; Zinc Finger E-box-Binding Homeobox 1

We aimed to test the ability of texture analysis to differentiate the spatial heterogeneity of (125)I-A5B7 anti-carcinoembryonic antigen antibody distribution by nano-single photon emission computed tomography (SPECT) in well-differentiated (SW1222) and poorly differentiated (LS174T) hepatic metastatic colorectal cancer models before and after combretastatin A1 di-phosphate anti-vascular therapy.. Nano-SPECT imaging was performed following tail vein injection of 20 MBq (125)I-A5B7 in control CD1 nude mice (LS174T, n=3 and SW1222, n=4), and CA1P-treated mice (LS174T, n=3; SW1222, n=4) with liver metastases. Grey-level co-occurrence matrix textural features (uniformity, homogeneity, entropy and contrast) were calculated in up to three liver metastases in 14 mice from control and treatment groups.. Before treatment, the LS174T metastases (n=7) were more heterogeneous than SW1222 metastases (n=12) (uniformity, P=0.028; homogeneity, P=0.01; contrast, P=0.045). Following CA1P, LS174T metastases (n=8) showed less heterogeneity than untreated LS174T controls (uniformity, P=0.021; entropy, P=0.006). Combretastatin A1 di-phosphate-treated SW1222 metastases (n=11) showed no difference in texture features compared with controls (all P>0.05).. Supporting the potential for novel imaging biomarkers, texture analysis of (125)I-A5B7 SPECT shows differences in spatial heterogeneity of antibody distribution between well-differentiated (SW1222) and poorly differentiated (LS174T) liver metastases before treatment. Following anti-vascular treatment, LS174T metastases, but not SW1222 metastases, were less heterogeneous.

Topics: Angiogenesis Inhibitors; Animals; Antibodies, Monoclonal; Carcinoembryonic Antigen; Cell Line, Tumor; Colorectal Neoplasms; Diphosphates; Female; Heterografts; Humans; Iodine Radioisotopes; Liver Neoplasms; Mice; Mice, Nude; Neoplasm Metastasis; Phenotype; Radiopharmaceuticals; Stilbenes; Tomography, Emission-Computed, Single-Photon

Epithelial to mesenchymal transition (EMT) is considered an important mechanism in tumor resistance to drug treatments; however, in vivo observation of this process has been limited. In this study we demonstrated an immediate and widespread EMT involving all surviving tumor cells following treatment of a mouse model of colorectal liver metastases with the vascular disruptive agent OXi4503. EMT was characterized by significant downregulation of E-cadherin, relocation and nuclear accumulation of β-catenin as well as significant upregulation of ZEB1 and vimentin. Concomitantly, significant temporal upregulation in hypoxia and the pro-angiogenic growth factors hypoxia-inducible factor 1-alpha, hepatocyte growth factor, vascular endothelial growth factor and transforming growth factor-beta were seen within the surviving tumor. The process of EMT was transient and by 5 days after treatment tumor cell reversion to epithelial morphology was evident. This reversal, termed mesenchymal to epithelial transition (MET) is a process implicated in the development of new metastases but has not been observed in vivo histologically. Similar EMT changes were observed in response to other antitumor treatments including chemotherapy, thermal ablation, and antiangiogenic treatments in our mouse colorectal metastasis model and in a murine orthotopic breast cancer model after OXi4503 treatment. These results suggest that EMT may be an early mechanism adopted by tumors in response to injury and hypoxic stress, such that inhibition of EMT in combination with other therapies could play a significant role in future cancer therapy.

Topics: Angiogenic Proteins; Animals; Antineoplastic Agents; Apoptosis; beta Catenin; Cadherins; Cell Hypoxia; Colorectal Neoplasms; Diphosphates; Down-Regulation; Epithelial-Mesenchymal Transition; Female; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms; Male; Mammary Neoplasms, Experimental; Mice; Mice, Inbred BALB C; Mice, Inbred CBA; Neoplasm Proteins; Neoplasm Transplantation; Neoplasm, Residual; Stilbenes; Up-Regulation

The use of a novel all-optical photoacoustic scanner for imaging the development of tumor vasculature and its response to a therapeutic vascular disrupting agent is described. The scanner employs a Fabry-Perot polymer film ultrasound sensor for mapping the photoacoustic waves and an image reconstruction algorithm based upon attenuation-compensated acoustic time reversal. The system was used to noninvasively image human colorectal tumor xenografts implanted subcutaneously in mice. Label-free three-dimensional in vivo images of whole tumors to depths of almost 10 mm with sub-100-micron spatial resolution were acquired in a longitudinal manner. This enabled the development of tumor-related vascular features, such as vessel tortuosity, feeding vessel recruitment, and necrosis to be visualized over time. The system was also used to study the temporal evolution of the response of the tumor vasculature following the administration of a therapeutic vascular disrupting agent (OXi4503). This revealed the well-known destruction and recovery phases associated with this agent. These studies illustrate the broader potential of this technology as an imaging tool for the preclinical and clinical study of tumors and other pathologies characterized by changes in the vasculature.

Topics: Angiogenesis Inhibitors; Animals; Antineoplastic Agents; Cell Line, Tumor; Colorectal Neoplasms; Diphosphates; Elasticity Imaging Techniques; Female; Humans; Mice; Mice, Nude; Neovascularization, Pathologic; Photoacoustic Techniques; Stilbenes; Treatment Outcome

Treatment of solid tumors with vascular disrupting agent OXi4503 results in over 90% tumor destruction. However, a thin rim of viable cells persists in the tumor periphery following treatment, contributing to subsequent recurrence. This study investigates inherent differences in the microenvironment of the tumor periphery that contribute to treatment resistance.. Using a murine colorectal liver metastases model, spatial morphological and molecular differences within the periphery and the center of the tumor that may account for differences in resistance to OXi4503 treatment were investigated. H&E staining and immunostaining were used to examine vessel maturity and stability, hypoxia and HIF1α levels, accumulation of immune cells, expression of proangiogenic factors/receptors (VEGF, TGF-β, b-FGF, and AT1R) and expression of EMT markers (ZEB1, vimentin, E-cadherin and β-catenin) in the periphery and center of established tumors. The effects of OXi4503 on tumor vessels and cell kinetics were also investigated.. Significant differences were found between tumor periphery and central regions, including association of the periphery with mature vessels, higher accumulation of immune cells, increased growth factor expression, minimal levels of hypoxia and increased evidence of EMT. OXi4503 treatment resulted in collapse of vessels in the tumor center; however vasculature in the periphery remained patent. Similarly, tumor apoptosis and proliferation were differentially modulated between centre and periphery after treatment.. The molecular and morphological differences between tumor periphery and center may account for the observed differential resistance to OXi4503 treatment and could provide targets for drug development to totally eliminate metastases.

Topics: Animals; Antineoplastic Agents; Apoptosis; beta Catenin; Cadherins; Cell Hypoxia; Cell Line, Tumor; Cell Proliferation; Colorectal Neoplasms; Diphosphates; Drug Resistance, Neoplasm; Fibroblast Growth Factors; Homeodomain Proteins; Hypoxia-Inducible Factor 1, alpha Subunit; Kruppel-Like Transcription Factors; Liver Neoplasms; Male; Mice; Mice, Inbred CBA; Stilbenes; Transforming Growth Factor beta; Tumor Microenvironment; Vascular Endothelial Growth Factor A; Vimentin; Zinc Finger E-box-Binding Homeobox 1

Hepatocellular carcinoma (HCC) and colorectal carcinoma with hepatic metastases (mCRC) are cancers with poor prognosis and limited therapeutic options. New approaches are needed and adoptive immunotherapy with Vgamma9Vdelta2 T lymphocytes represents an attractive strategy. Indeed, Vgamma9Vdelta2 T cells were shown to exhibit efficient lytic activity against various human tumor cell lines, and in vitro Vgamma9Vdelta2 T expansion protocol based on single phosphoantigen stimulation could be easily performed for healthy donors. However, a low proliferative response of Vgamma9Vdelta2 T cells was observed in about half of the cancer patients, leading to an important limitation in the development of Vgamma9Vdelta2 T cell-based immunotherapy. Here, for the first time in the context of cancer patients, Vgamma9Vdelta2 T cell expansions were performed by co-culturing peripheral blood mononuclear cell (PBMCs) with autologous dendritic cells (DCs) pretreated with aminobisphosphonate zoledronate. For patients not responding to the conventional culture protocol, co-culture of PBMC with zoledronate-pretreated DCs induced strong cell expansion and allowed reaching a minimal rate of purity of 70% of Vgamma9Vdelta2 T cells. The potent immunostimulatory activity of zoledronate-treated DCs was associated with higher amount of isopentenyl pyrophosphate (IPP) in the culture and was correlated with better ability to activate Vgamma9Vdelta2 T cells as measured by IFN-gamma production. Moreover, we demonstrated that the cytotoxic level of Vgamma9Vdelta2 T cells against freshly autologous tumor cells isolated from patients could be significantly increased by pretreating the tumor cells with zoledronate. Thus, this method of generating Vgamma9Vdelta2 T cells leads eligible for Vgamma9Vdelta2 T cell adoptive immunotherapy the HCC and mCRC patients.

Topics: Adenocarcinoma; Aged; Blotting, Western; Bone Density Conservation Agents; Carcinoma, Hepatocellular; Cell Differentiation; Cell Proliferation; Coculture Techniques; Colorectal Neoplasms; Cytotoxicity, Immunologic; Dendritic Cells; Diphosphates; Diphosphonates; Female; Flow Cytometry; Hemiterpenes; Humans; Imidazoles; Immunotherapy, Adoptive; Liver Neoplasms; Male; Middle Aged; Organophosphorus Compounds; Receptors, Antigen, T-Cell, gamma-delta; T-Lymphocyte Subsets; Zoledronic Acid

Oxi4503 is a potent vascular targeting agent belonging to the family of combretastatins. These agents produce an acute reduction in tumor blood flow leading to tumor necrosis. Despite evidence of its efficacy in certain malignancies, the effect on colorectal liver metastases remains largely unknown. This study investigates the effect of Oxi4503 on colorectal liver metastases in a murine model.. The effect of a single dose of Oxi4503 on established tumors in a murine model of colorectal liver metastases was assessed following administration of 1-50 mg/kg Oxi4503. In addition, the effects of continuous, daily and intermittent dosing (1-5 mg/kg) on tumor necrosis and growth were studied by quantitative histological and stereological analysis. The effect of multiple dosing on long-term survival was also assessed using the Kaplan-Meier analysis. The microvascular effects of therapy were studied by scanning electron microscopy of microvascular resin casts.. A single dose of 5 or 50 mg/kg of Oxi4503 produced significant tumor necrosis compared to the controls. Subcutaneous continuous dosing infusion with Oxi4503 at 1 mg/kg/day reduced tumor growth compared to the controls, but was associated with marked systemic toxicity. Daily administration over 21 days was associated with significant mortality. Intermittent dosing of Oxi4503 (two doses, 3 days apart) produced the greatest reduction in tumor growth with minimal toxicity and conferred a significant survival advantage. Microvascular casts demonstrated significant disruption of tumor vessels.. A single dose of Oxi4503 produced significant necrosis and microvascular injury in colorectal liver metastases. Intermittent dosing with Oxi4503 produced the maximum reduction in tumor growth, minimal toxicity, and a significant improvement in survival. Oxi4503 is a potential anticancer agent. Further research into its mechanism of action and its synergistic use with other therapies is warranted.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cell Proliferation; Colorectal Neoplasms; Diphosphates; Dose-Response Relationship, Drug; Drug Administration Schedule; Infusion Pumps, Implantable; Infusions, Parenteral; Injections, Intraperitoneal; Liver Neoplasms, Experimental; Male; Mice; Mice, Inbred CBA; Microcirculation; Necrosis; Regional Blood Flow; Stilbenes; Time Factors

OXi4503 retards tumor growth in a dose-dependent manner and improves survival in a murine model of colorectal liver metastases. This agent causes extensive vascular shutdown by selectively altering the tubulin cytoskeleton within the endothelial cells of tumor vessels. The destruction of tumor vessels is incomplete, however, and tumor revascularization occurs after the treatment. This study evaluates the pattern of microcirculatory changes and alterations to the ultrastructural properties of the tumor vasculature that result from OXi4503 treatment. Male CBA mice were induced with liver metastases via an intrasplenic injection of a murine-derived colorectal cell line. After administering a single intraperitoneal dose of OXi4503, changes in tumor perfusion, microvascular architecture and permeability were assessed at various time points. One hour after a 100-mg/kg dose of OXi4503, a significant decrease in the percentage of tumor perfusion (63.96+/-1.98 in controls versus 43.77+/-2.71 in treated mice, P<0.001) was observed, which was still evident 5 days after the treatment. Substantial tumor microvascular damage and minimal normal liver injury were observed. Tumor vascular permeability was significantly elevated 45 min after the OXi4503 treatment (67.5+/-3.60 in controls versus 80.5+/-2.24 microg/g, P<0.05). The findings suggest that OXi4503 selectively targets tumor vessels and causes immediate microvascular destruction. Even at the maximum tolerated dose, however, residual patent tumor vessels were still present after treatment, implying incomplete tumor destruction. A combination of OXi4503 with other chemotherapeutic modalities might achieve complete tumor eradication and improve long-term survival.

Topics: Angiogenesis Inhibitors; Animals; Blood Vessels; Capillaries; Capillary Permeability; Carcinogens; Colorectal Neoplasms; Dimethylhydrazines; Diphosphates; Evans Blue; Laser-Doppler Flowmetry; Liver Neoplasms; Male; Mice; Mice, Inbred CBA; Microscopy, Confocal; Microscopy, Electron, Scanning; Regional Blood Flow; Stilbenes; Tissue Fixation