Higher Vessel Density Research Articles

Microvessel quantification in benign and malignant ovarian tumors

Microvessel density (MVD) in 92 paraffin sections of ovarian samples of different histologic subtypes was correlated with microvessel counts from 58 corresponding frozen sections. Anti-human von Willebrand factor antibody was used as an endothelial marker. MVD was performed in neovascular hotspots using a Quantimet 500+ Image Analyzer. The highest vessel density (HVD) and average vessel density (AVD) of three fields at the × 200 and × 400 magnification were recorded. There was a strong correlation between the HVD and AVD at the × 200 and × 400 magnifications when comparing fixed with frozen sections (correlation coefficients at × 200 for the HVD was 0.37, P = 0.005 and AVD was 0.30, P = 0.02; correlation coefficients at × 400 for the HVD was 0.38, P = 0.003 and AVD was 0.37, P = 0.004). In the fixed tissue, the HVD and AVD at both these magnifications were significantly greater in the group containing functional cysts; this was also the case for the frozen sections. These findings are consistent with the development of a microcirculation necessary for the growth and maturation of such cysts, and this appears to be greater than that in tumors. The good correlation between MVD in fixed and frozen sections suggests that such observations represent a true reflection of ovarian angiogenesis in both physiologic and pathologic states.

Increased Vascularization Predicts Favorable Outcome in Follicular Lymphoma

In malignant lymphoma, angiogenesis has been associated with adverse outcome or more aggressive clinical behavior. This correlation has been established in groups of patients with a large heterogeneity regarding lymphoma subtypes and treatment regimens. The aim of this study is to investigate the significance of vascularization in patients with follicular lymphoma receiving uniform first-line treatment. We assessed microvessel density (MVD) in pretreatment lymph node biopsies of 46 previously untreated patients with follicular lymphoma using anti-CD34 immunohistochemical staining and interactive quantification. In a selection of cases, vascular endothelial growth factor (VEGF)-RNA in situ hybridization was done. Patients were treated with cyclophosphamide-vincristine-prednisone induction chemotherapy combined with IFN-alpha2b. Thirty-six patients responded and received IFN-alpha as maintenance therapy. MVD ranged from 10 to 70 per measurement field of 0.19 mm2 (median, 38). Median progression-free survival was 47 months in patients with MVD in the highest tertile and only 13 months in patients with lower MVD. Overall survival in patients with low vessel density was 59 months. In patients with high vessel density, median overall survival was not reached. Multivariate analysis indicated that MVD was independently associated with overall survival. There was a lack of correlation between VEGF-RNA expression and vessel density. This study shows that in follicular lymphoma increased vascularization is associated with improved clinical outcome. Furthermore, VEGF-A expression seems not to be involved in follicular lymphoma angiogenesis.

High LYVE-1–Positive Lymphatic Vessel Numbers Are Associated with Poor Outcome in Breast Cancer

The clinical significance of intratumoral or peritumoral lymph vessel density is not known. LYVE-1, a lymphatic endothelium-specific hyaluronan receptor, is a novel lymphatic vessel marker that is expressed on lymph vessel endothelial cells of both normal and neoplastic tissues. We investigated expression of LYVE-1 by immunohistochemistry in 180 unilateral, invasive ductal breast carcinomas and assessed the presence and density of lymph vessels within the tumor and at the tumor periphery. A minority (12%) of breast carcinomas had intratumoral lymph vessels, whereas peritumoral lymph vessels were identified in almost all cases (94%). No substantial association was found between the number of LYVE-1-positive vessels and the number of CD31 or vascular endothelial growth factor receptor-3-positive vessels, or vascular endothelial growth factor-C expression. The number of metastatic axillary lymph nodes increased in parallel with increasing lymph vessel counts (P = 0.033). A higher than the median lymph vessel count at the tumor periphery was significantly associated with unfavorable distant disease-free survival and overall survival. Women with high peritumoral lymph vessel density had only 58% (95% confidence interval, 46-70%) 5-year distant disease-free survival as compared with 74% (66-83%) among those with a low peritumoral lymph vessel density (P = 0.0088). In contrast, the presence of intratumoral lymph vessels was associated with neither axillary nodal status nor survival. Lymph vessel density was not an independent prognostic factor in a multivariate survival analysis. A high peritumoral lymph vessel density is associated with a poor outcome in ductal breast cancer.

Continuous low-dose chemotherapy plus inhibition of cyclooxygenase-2 as an antiangiogenic therapy of glioblastoma multiforme

Glioblastoma multiforme (GBM) represents the prototype of an angiogenic tumor. Recently, the continuous low-dose scheduling of chemotherapeutic drugs in combination with an inhibition of cyclooxygenase-2 (COX-2) has been suggested as a novel anti-angiogenic approach. The aim of this study was to evaluate the safety and activity of continuous low-dose temozolomide (TMZ) plus the COX-2 inhibitor rofecoxib in patients with newly diagnosed GBM. In vitro, endothelial cells were characterized by a tenfold higher sensitivity to TMZ than glioma cells. Consequently, a subgroup of patients with incompletely resected GBM (n=13) was divided into three groups aiming at a dose escalation to 1/10 of the daily MTD for TMZ: (A) TMZ 10 mg/m2 every third day and rofecoxib 25 mg/d; (B) TMZ 10 mg/m2/d and rofecoxib 25 mg/d; (C) TMZ 5 mg/m2 twice a day and rofecoxib 12.5 mg twice a day. COX-2, VEGF, VEGF Receptor-2, and CD34 were assessed immunohistochemically, in the clinical setting. The mean follow-up period was 15 months. We observed no severe toxicity attributable to the therapy. Quality of life was not impaired. For the whole study population, median time to progression and overall survival were 8 months and 16 months, respectively. Immunohistochemistry suggested that tumors with higher vessel densities were characterized by a significantly better control than those with lower vessel densities. Continuous low-dose TMZ plus rofecoxib is feasible, safe, and maintains good quality of life. This study is indicative of an anti-angiogenic efficacy of continuous low-dose TMZ plus rofecoxib in GBMs, especially in those tumors that are characterized by a high angiogenic activity.

High LYVE-1 positive lymphatic vessel numbers are associated with axillary lymph node metastases and poor outcome in breast cancer

9518 Background: The clinical significance of intratumoral or peritumoral lymph vessel density is not known. LYVE-1, a lymphatic endothelium specific hyaluronan receptor, is a novel lymphatic vessel marker which is expressed on lymph vessel endothelial cells of both normal and neoplastic tissues. Methods: We investigated expression of LYVE-1 by means of immunhistoochemistry in a series of 180 unilateral, invasive ductal breast carcinomas, in order to assess the correlation between the density of lymph vessels, the incidence of lymph node metastases and clinical outcome. Results: A minority (12%) of breast carcinomas had intratumoral lymph vessels, whereas peritumoral lymph vessels were identified in almost all cases (94%). No significant association was found between the number of LYVE-1 positive vessels and the number of CD31 or VEGFR-3 (vascular endothelial growth factor receptor-3) positive vessels. The number of metastatic axillary lymph nodes increased in parallel with increasing lymph vessel counts (P= 0.033). A higher than the median lymph vessel count at the tumor periphery was significantly associated with unfavorable distant disease-free survival (DDFS) and overall survival. Women with high peritumoral lymph vessel density had only 58% (95% CI, 46 to 70%) 5-year DDFS as compared with 74% (66 to 83%) among those with a low peritumoral lymph vessel density (P=0.0088). In contrast, the presence of intratumoral lymph vessels was associated with neither axillary nodal status nor survival. Lymph vessel density was not an independent prognostic factor in a multivariate survival analysis. Conclusions: A high peritumoral lymph vessel density is associated with the presence of frequent axillary node metastases and a poor outcome in invasive ductal breast cancer. No significant financial relationships to disclose.

High LYVE-1 positive lymphatic vessel numbers are associated with axillary lymph node metastases and poor outcome in breast cancer

9518 Background: The clinical significance of intratumoral or peritumoral lymph vessel density is not known. LYVE-1, a lymphatic endothelium specific hyaluronan receptor, is a novel lymphatic vessel marker which is expressed on lymph vessel endothelial cells of both normal and neoplastic tissues. Methods: We investigated expression of LYVE-1 by means of immunhistoochemistry in a series of 180 unilateral, invasive ductal breast carcinomas, in order to assess the correlation between the density of lymph vessels, the incidence of lymph node metastases and clinical outcome. Results: A minority (12%) of breast carcinomas had intratumoral lymph vessels, whereas peritumoral lymph vessels were identified in almost all cases (94%). No significant association was found between the number of LYVE-1 positive vessels and the number of CD31 or VEGFR-3 (vascular endothelial growth factor receptor-3) positive vessels. The number of metastatic axillary lymph nodes increased in parallel with increasing lymph vessel counts (P= 0.033). A higher than the median lymph vessel count at the tumor periphery was significantly associated with unfavorable distant disease-free survival (DDFS) and overall survival. Women with high peritumoral lymph vessel density had only 58% (95% CI, 46 to 70%) 5-year DDFS as compared with 74% (66 to 83%) among those with a low peritumoral lymph vessel density (P=0.0088). In contrast, the presence of intratumoral lymph vessels was associated with neither axillary nodal status nor survival. Lymph vessel density was not an independent prognostic factor in a multivariate survival analysis. Conclusions: A high peritumoral lymph vessel density is associated with the presence of frequent axillary node metastases and a poor outcome in invasive ductal breast cancer. No significant financial relationships to disclose.

Microvessel density in progressive meningiomas and its influence on time to tumour recurrence

1563 Background: Meningiomas constitute circumscribed intracranial tumours of limited resectability. Adjuvant therapy is applied for growth control of incompletely resected tumours. However, radiotherapy is limited for tumours in certain locations due to the presence of adjacent radiosensitive neural structures. In such cases, chemotherapy is mandatory for tumour control, but hitherto used chemotherapy protocols showed unsatisfactory therapeutic effects. Methods: In order to develop new approaches based upon angiogenetic properties, we analysed systematically tumour vascularization in a set of 26 recurrent or inoperable meningiomas of 13 patients using the endothelial cell marker anti-CD34 for immunostaining. We determined microvessel density (MVD) within the tumour area with the highest vessel density by counting all anti-CD34 immunostained vessels at a magnification of x 200 within an examination area of 0.25 mm2 using an eye grid. Further, we analysed expression of vascular endothelial growth factor (VEGF) at the messenger RNA and protein levels. Results: MVD ranged from 22 to 149 vessels/standard area with a median of 50.5. Focal or widespread expression of VEGF messenger RNA was detectable in 17/19 analysed samples and VEGF protein expression was observed in all tumour samples. Clinically, the time to recurrence of tumours with high ( ≥ 50.5) MVD ( 28.4 months) was significantly shorter as compared to tumours with low MVD ( 72.1 months; p = 0.0136). Conclusions: Our data indicate that MVD may influence the progression of meningiomas. Due to the expression of VEGF messenger RNA and/or VEGF protein in all tumour samples, anti-VEGF strategies may exert a beneficial therapeutic effect in progressive meningiomas. No significant financial relationships to disclose.

Microvessel density in progressive meningiomas and its influence on time to tumour recurrence

1563 Background: Meningiomas constitute circumscribed intracranial tumours of limited resectability. Adjuvant therapy is applied for growth control of incompletely resected tumours. However, radiotherapy is limited for tumours in certain locations due to the presence of adjacent radiosensitive neural structures. In such cases, chemotherapy is mandatory for tumour control, but hitherto used chemotherapy protocols showed unsatisfactory therapeutic effects. Methods: In order to develop new approaches based upon angiogenetic properties, we analysed systematically tumour vascularization in a set of 26 recurrent or inoperable meningiomas of 13 patients using the endothelial cell marker anti-CD34 for immunostaining. We determined microvessel density (MVD) within the tumour area with the highest vessel density by counting all anti-CD34 immunostained vessels at a magnification of x 200 within an examination area of 0.25 mm2 using an eye grid. Further, we analysed expression of vascular endothelial growth factor (VEGF) at the messenger RNA and protein levels. Results: MVD ranged from 22 to 149 vessels/standard area with a median of 50.5. Focal or widespread expression of VEGF messenger RNA was detectable in 17/19 analysed samples and VEGF protein expression was observed in all tumour samples. Clinically, the time to recurrence of tumours with high ( ≥ 50.5) MVD ( 28.4 months) was significantly shorter as compared to tumours with low MVD ( 72.1 months; p = 0.0136). Conclusions: Our data indicate that MVD may influence the progression of meningiomas. Due to the expression of VEGF messenger RNA and/or VEGF protein in all tumour samples, anti-VEGF strategies may exert a beneficial therapeutic effect in progressive meningiomas. No significant financial relationships to disclose.

Dynamic contrast-enhanced MRI for assessing the disease activity of multiple myeloma: A comparative study with histology, proangiogenic cytokines and clinical markers

6719 Background: Dynamic contrast-enhanced MRI (dMRI) of the bone marrow has been used for assessing treatment response in multiple myeloma (MM). Aim of this study was to examine whether parameters of dMRI reflect the degree of infiltration and vessel density in corresponding bone marrow biopsy specimens. Furthermore levels of proangiogenic cytokines in peripheral blood and bone marrow were compared with findings of dMRI. Methods: The pelvis of 24 patients with MM was examined using Gd-DTPA-enhanced dMRI. Biopsy was obtained from the spina iliaca posterior superior. Using a two-compartment model, the parameters amplitude A and exchange rate constant k21 in the biopsied region were calculated and compared with the histological and clinical data. The proangiogenic cytokines Hepatocyte Growth Factor (HGF), Vascular Endothelial Growth Factor (VEGF) and Basic Fibroblast Growth Factor (bFGF) were measured in peripheral blood and bone marrow of 36 patients. The results were correlated with dMRI parameters. Results: DMRI parameters were significantly higher in lesions with marked infiltration than with mild or no infiltration (p<0.05). Amplitude A, but not exchange rate constant k21 was higher in lesions with high vessel-density at histology (p=0.01). Higher levels of the exchange rate consant k21 were found in presence of increased serum immunoglobulins. We detected a significant positive correlation of HGF concentration in peripheral blood with amplitude A of the lumbar spine (p = 0,05). Conclusions: Increased contrast uptake in the bone marrow of MM patients indicates at least moderate tumor involvement. The contrast enhancement correlates with the degree of plasma cell infiltration and vessel-density. The correlation between HGF and bone marrow microcirculation as detected by dMRI supports the role of HGF in regulation of bone marrow microcirculation and angiogenesis in MM. No significant financial relationships to disclose.

Vessel density, proliferation, and immunolocalization of vascular endothelial growth factor in juvenile nasopharyngeal angiofibromas.

Juvenile nasopharyngeal angiofibroma (JNA) is a rare, highly vascularized neoplasm of the nasopharynx that affects boys and young men. The underlying dysregulated molecular mechanisms remain unclear. The participation of angiogenic growth factors has been suggested, but few studies have been published. To evaluate the expression and localization of vascular endothelial growth factor (VEGF), proliferating cells, and vessel density in JNA. Immunohistochemical examination of 10 consecutive JNAs (8 primary tumors and 2 recurrent tumors). Paraffin-embedded and cryopreserved JNA samples were included. VEGF-, CD31-, and Ki67-specific antibodies were applied and visualized using light microscopy. Vascularization was determined by counting CD31-positive vessels. Proliferating and VEGF-expressing vessels as well as stromal cells were quantified by the same method. Patients' age at the time of surgery and tumor stage were correlated with the immunohistochemical data. All tumors were heavily vascularized, but major differences were noted between the samples. About half of the vessels were proliferating (Ki67 positive) and half of the Ki67-positive cells were also VEGF positive. The tumor stroma was VEGF positive in 8 of 10 samples and proliferating in 5 of these 8. The 5 samples with both VEGF- and Ki67-positive stroma showed high vessel densities. No correlation was observed between age or tumor stage and vessel density, VEGF expression, or Ki67 expression. In JNA, VEGF is frequently expressed by stromal cells and vessels and is associated with proliferation and increased vessel density. We suggest the promotion of vascularization by VEGF, but the involvement of androgens in JNA angiogenesis still needs to be analyzed.

Growth rings, growth ring formation and age determination in the mangrove Rhizophora mucronata.

The mangrove Rhizophora mucronata has previously been reported to lack annual growth rings, thus barring it from dendrochronological studies. In this study the reported absence of the growth rings was reconsidered and the periodic nature of light and dark brown layers visible on polished stem discs investigated. In addition, the formation of these layers in relation to prevailing environmental conditions, as well as their potential for age determination of the trees, was studied. Trees of known age were collected and a 2.5-year cambial marking experiment was conducted to determine the periodic nature of the visible growth layers. Annual indistinct growth rings were detected in R. mucronata and are defined by a low vessel density earlywood and a high vessel density latewood. The formation of these growth rings and their periodic nature was independent from site-specific environmental conditions in two forests along the Kenyan coast. However, the periodic nature of the rings was seriously affected by slow growth rates, allowing accurate age determination only in trees with radial growth rates above 0.5 mm year(-1). The onset of the formation of the low vessel density wood coincided with the onset of the long rainy season (April-May) and continues until the end of the short rainy season (November). The high vessel density wood is formed during the dry season (December-March). Age determination of the largest trees collected in the two studied forests revealed the relatively young age of these trees (+/-100 years). This study reports, for the first time, the presence of annual growth rings in the mangrove R. mucronata, which offers further potential for dendrochronological and silvicultural applications.

Prognostic Value of Intratumoral Vessel Density in Cutaneous Mast Cell Tumours of the Dog

The biological behaviour of canine cutaneous mast cell tumours (MCTs) is highly variable. The aim of this study was to investigate whether intratumoral microvessel density (IMVD), as an indicator of angiogenesis, was predictive of biological behaviour in MCTs of canine skin, and to relate this parameter to histological grade and other histomorphological features. IMVD was evaluated by immunohistochemical labelling of the endothelial marker factor VIII (Von Willebrand's factor)-related antigen in 32 primary cutaneous MCTs. Computer image analysis was used to measure IMVD, expressed as the number of microvessels per square millimetre. Cases were assigned to low and high vessel density groups, the median value (14.1) being used as the “cut-off”. Kaplan–Meier-estimated survival curves of the groups revealed that IMVD was significantly associated with survival time ( P=0.046). One-way analysis of variance, performed to compare the IMVD values of tumours of different histological grades, showed a significant difference between grades I and III ( P=0.0002). There was a significant difference in IMVD between moderately invasive and highly invasive tumours ( P=0.002), and between tumours with different numbers of mitoses ( P=0.0046). In multivariate analysis, performed to test the combined influence on survival of each parameter, only the mitotic index and IMVD were independent prognostic variables ( P=0.00019). The relation of angiogenesis to biological behaviour and histological parameters of malignancy of cutaneous MCTs was consistent with previous findings in human and animal tumours.

Distinct Role of Fibroblast Growth Factor-2 and Vascular Endothelial Growth Factor on Tumor Growth and Angiogenesis

Tumors express more than a single angiogenic growth factor. To investigate the relative impact of fibroblast growth factor-2 (FGF-2) and vascular endothelial growth factor (VEGF) on tumor growth and neovascularization, we generated tumor cell transfectants differing for VEGF and/or FGF-2 expression. Human endometrial adenocarcinoma HEC-1-B-derived Tet-FGF-2 cells that express FGF-2 under the control of the tetracycline-responsive promoter (Tet-off system) were further transfected with a VEGF(121) anti-sense (AS-VEGF) cDNA. Next, Tet-FGF-2 and AS-VEGF/Tet-FGF-2 cells were transplanted subcutaneously in nude mice that received tetracycline or not in the drinking water. Simultaneous expression of FGF-2 and VEGF in Tet-FGF-2 cells resulted in fast-growing lesions characterized by high blood vessel density, patency and permeability, and limited necrosis. Blood vessels were highly heterogeneous in size and frequently associated with pericytes. Inhibition of FGF-2 production by tetracycline caused a significant decrease in tumor burden paralleled by a decrease in blood vessel density and size. AS-VEGF expression resulted in a similar reduction in blood vessel density associated with a significant decrease in pericyte organization, vascular patency, and permeability. The consequent decrease in tumor burden was paralleled by increased tumor hypoxia and necrosis. A limited additional inhibitory effect was exerted by simultaneous down-regulation of FGF-2 and VEGF expression. These findings demonstrate that FGF-2 and VEGF stimulate vascularization synergistically but with distinctive effects on vessel functionality and tumor survival. Blockade of either one of the two growth factors results in a decrease in blood vessel density and, consequently, in tumor burden. However, inhibition of the expression of VEGF, but not of FGF-2, affects also vessel maturation and functionality, leading to tumor hypoxia and necrosis. Our experimental model represents an unique tool to investigate anti-neoplastic therapies in different angiogenic environments.

Preoperative bowel ultrasound corresponds to intraoperative and histopathological findings in active Crohn's disease

Bowel ultrasound has recently been proved useful in the assessment of bowel disease. Active Crohns disease (CD) is associated with neovasculanzation, and bowel loops affected by CD are thickened and loss of bowel wall stratification are often seen in affected bowel segments. These findings are readily visible with high4requency transcutaneous ultrasound. However, uncertainty persists as to its diagnostic role. Aim: to compare preoperative ultrasound with intraoperative and histopathological findings in active CD. Methods: 15 patients with active CD admitted for surgery underwent bowel ultrasound (Siemens elegra, 7.5 MHz) the day before operation. The extent and localisation of disease, findings of stenosis, wall thickness and wall stiffness detected on US were compared with those seen intraoperatively. Stratification of wall layers and density of intramural blood vessels were evaluated by power Doppler ultrasound and compared with histopathology. Results: Ileocecal involvment was observed in 5 patients, small bowel in 8 pattents, only large bowel in 1 patients, and combined small and large bowel in 1 patient. 12 patients were resected, tn one patient only stricturoplasty and in 2 patients both resection and stricruroplasty were performed. Agreement was observed between ultrasound and surgery: localisation of affected loops: 100%, number of affected loops: 54% (underestimation by ultrasound), stenosis: 92%, wall stiffness/fibrosis: 100%. 3 fmtulae were seen on ultrasound and 2 were demonstrated intraoperatively. Loss of stratification of wall layers were seen on ultrasound in 2 patients, corresponding with transmural fibrosis seen on histology. High density of intramural vessels were seen on ultrasound in 10 patients and these findings were seen as neovascularization in the inflamed tissue between mucosa and submucosa and as dilatation of already existing vessels in the submucosa on histology. Inflammation in the myemeric plexus occurred in 13 patients. Conclusion: Agreement between ultrasound and surgery was found for localisation and stenosis Loss of bowel wall stratification on US was confirmed as fibrotic tissue on histology, and intramural vessels on ultrasound could be demonstrated histologically as both neovascularization in inflamed tissue and dilation of submucosal vessels.

Expression of vascular endothelial growth factor in human dysfunctional temporomandibular joint discs

A high density of blood vessels is found in specimens of temporomandibular joint (TMJ) disc at any stage of internal derangement of the joint, but the factors responsible for angiogenesis in the disc have not been described. The purpose here was to investigate, in human TMJ discs, the expression of vascular endothelial growth factor (VEGF), a multifunctional cytokine that contributes to angiogenesis. Specimens, free of significant morphological alterations and with varying degrees of disc tissue degeneration/regeneration, were studied by immunohistochemistry for VEGF in order to correlate immunohistochemical with histopathological findings. In normal discs and discs with minor pathological changes, fibroblast-like cells, fibrochondrocytes and chondrocyte-like cells were either not or only weakly immunostained by VEGF antibody. In disc specimens from internal derangement of the TMJ with significant tissue degeneration/regeneration, VEGF was consistently expressed. In these specimens, immunoreaction products for VEGF were observed both in the disc and in the endothelial cells of newly formed vessels. This VEGF immunolocalization is consistent with the stimulation of angiogenesis and the morphogenesis and differentiation of chondrocytes. Therefore VEGF expression by disc chondrocyte-like cells might reflect the action of the cytokine as an inducer of angiogenesis and as an autocrine signal for cells of the chondrogenic lineage.

Effects of mid-season frost and elevated growing season temperature on stomatal conductance and specific xylem conductivity of the arctic shrub, Salix pulchra.

An increased risk of frost is expected during the growing season, as climate warming increases spring temperatures in the Arctic. Because deciduous species have a growth season limited in length and also have generally larger conduit volumes, they are more likely than evergreens to be injured by freeze-thaw-induced cavitation during the growing season. To test whether growth at elevated temperature increases susceptibility to freeze-thaw damage, we grew a deciduous arctic shrub species (Salix pulchra Cham.) in simulated Alaskan summer temperatures and at 5 degrees C above the ambient simulation (+5 degrees C plants) in controlled environments. Stem specific hydraulic conductivity (k(s)) and leaf stomatal conductance (g(s)) were measured in plants grown at both temperatures before and after a freeze treatment simulating a mid-season frost. Before the freeze treatment, specific xylem conductivity was 2.5 times higher and stomatal conductances were 1.3 times higher in +5 degrees C plants than in ambient-grown plants. Reductions in hydraulic conductivity and stomatal conductance as a result of the freeze were 3.5 and 1.8 times greater respectively in +5 degrees C plants than in ambient-grown plants. Many of the +5 degrees C plants showed extensive leaf damage. Plants grown in the two treatments also differed in comparative xylem anatomy; +5 degrees C plants had larger vessel diameters (25.4 versus 22.6 micro m) and higher vessel densities (71 versus 67.4 vessels mm(-2)) than ambient-grown plants. Our results suggest that higher growing season temperatures will increase the susceptibility of arctic deciduous shrubs to frost damage, which may offset their competitive growth advantage.

Myogenic Akt signaling regulates blood vessel recruitment during myofiber growth.

Blood vessel recruitment is an important feature of normal tissue growth. Here, we examined the role of Akt signaling in coordinating angiogenesis with skeletal muscle hypertrophy. Hypertrophy of C2C12 myotubes in response to insulin-like growth factor 1 or insulin and dexamethasone resulted in a marked increase in the secretion of vascular endothelial growth factor (VEGF). Myofiber hypertrophy and hypertrophy-associated VEGF synthesis were specifically inhibited by the transduction of a dominant-negative mutant of the Akt1 serine-threonine protein kinase. Conversely, transduction of constitutively active Akt1 increased myofiber size and led to a robust induction of VEGF protein production. Akt-mediated control of VEGF expression occurred at the level of transcription, and the hypoxia-inducible factor 1 regulatory element was dispensable for this regulation. The activation of Akt1 signaling in normal mouse gastrocnemius muscle was sufficient to promote myofiber hypertrophy, which was accompanied by an increase in circulating and tissue-resident VEGF levels and high capillary vessel densities at focal regions of high Akt transgene expression. In a rabbit hind limb model of vascular insufficiency, intramuscular activation of Akt1 signaling promoted collateral and capillary vessel formation and an accompanying increase in limb perfusion. These data suggest that myogenic Akt signaling controls both fiber hypertrophy and angiogenic growth factor synthesis, illustrating a mechanism through which blood vessel recruitment can be coupled to normal tissue growth.

In vivo differentiation of pigmented skin tumors with laser Doppler perfusion imaging

Malignant melanomas show a higher heterogeneity in their architecture and a higher vessel density because of neovascularization compared to benign melanocytic skin tumours. In this study the validity of the newly developed Laser Doppler Perfusion Imager (LDPI) with a lateral resolution of 100 microns in the differential diagnosis of pigmented skin tumours was investigated. The perfusion of 116 pigmented skin tumours was s measured with LDPI; 44 malignant melanomas, five melanoma metastases, 59 dysplastic nevi and eight basal cell carcinomas were studied before excision for precise histological diagnosis. There is a significantly higher perfusion of the malignant melanomas (3.15 +/- 1.87 AU) compared to dysplastic nevi (1.14 +/- 0.97 AU) (p < 0.01). By calculating a ratio of the mean perfusion in the tumour and the mean perfusion in adjacent healthy skin, the potential source of error because of regional differences in perfusion is eliminated. The ratio of malignant melanomas (10.78 +/- 9.18) is significantly higher than these of melanoma metastases (4.20 +/- 1.66), basal cell carcinomas (3.24 +/- 1.32) and dysplastic nevi (2.85 +/- 1.32). The high resolution LDPI has the potential to be a non-invasive screening method for preoperative differential diagnosis of pigmented skin tumours. Besides the epiluminescence microscopy and sonographic determination of the tumour thickness, we have now the possibility to get preoperative information about tumour vascularization.

Wood and Bark Anatomy of Myricaceae: Relationships, Generic Definitions, and Ecological Interpretations

Wood anatomy of the single species of Canacomyrica (hitherto not studied) shows that it belongs in Myricaceae, although it differs from other genera in several respects (axial parenchyma grouped in bands or columns as well as diffuse; Heterogeneous Type I rays; more numerous bars per perforation plate). The latter two features are primitive for the family. The four genera (Canacomyrica. Comptonia, Morella, and Myrica s.s.) differ from each other not only by qualitative features but by quantitative features (feature means in genera mostly non- overl apping). Wood of Comptonia and Myri ca s.s. lacks chambered crystals in axial parenchyma and ray crystals. Wood of Myrica s.s. has tracheids in latewood but fiber-tracheids in earl ywood. Diagnostic generic summaries are presented. Features of Myricaceae such as scalarifom perforation plates, presence of (true) tracheids , ray types , chambered encapsulated crystals in axial parenchyma, and bark anatomy correspond with character states and expressions in Betulaceae, Casuarinaceae, Corylaceae, Juglandaceae (including Rhoipteleaceae), Ticodendraceae and, to a lesser extent, Fagaceae and Nothofagaceae. This grouping of families can be found as Fagales in recent DNA trees. The predominance of tracheids in basal Fagales such as Myricaceae and Ticodendraceae suggests that origin of vasicentric tracheids which occur in combination with libriform fibers in Fagaceae is the product of tracheid dimorphism. Low imperforate tracheid length to vessel element length ratios (FN ratios) in Myricaceae are a probable indication of wood primitiveness. Quantitative vessel features of Myricaceae, as combined in Mesomorphy Ratio values, characterize wood of Myricaceae as a whole, but at the species level such values correspond to respective habitats; notably high vessel density in Comptonia may represent greater conductive safety appropriate to relatively dry habitats.

Differential assessment of angiogenic activity and of vascular survival ability (VSA) in breast cancer.

Recent reports provide evidence that some growth factors behave as inhibitors of the apoptosis of the endothelial cells, bringing forward the concept of vascular survival as a post-angiogenesis process. At least two different vasculature development processes occur within a tumor: the angiogenic (formation of new vessels) and the vascular survival pathway, which is devoted to the preservation of the newly-formed vessels in layers that lose contact with the adjacent normal tissue. We developed a method to assess these processes in tissue samples. We noted that differences among tumors may exist not only in the tumor angiogenic activity (TAA) but also in the vascular survival ability (VSA). One third of the highly angiogenic breast cancer cases examined had a poor ability to maintain high vessel density in inner tumor areas. Both parameters are independently related to prognosis, while VSA was directly related to tumor dimensions and node involvement. Patients with high TAA and VSA had a particularly poor prognosis. It is suggested that although cancer angiogenic activity is important for the local invasion and dissemination into vessels and lymphatics, the VSA may be important for the effective formation of viable tumor foci in lymph nodes or distant organs. Recognition and quantification of the vascular survival ability in human tumors may significantly improve the prognostic value of the assessment of tumor vasculature, and may help to stratify patients for clinical trials with novel anti-angiogenic or angiotoxic drugs. Elucidation of the pathways may provide additional targets for antiangiogenic therapy.