Total Number Of Vessels Research Articles

Loss of the atypical inflammatory response in juvenile and aged rats

Epidemiological evidence indicates that the severity of many human neuropathologies is often age-related, and this also appears true in rodent models of human disease. In this study, we examined the inflammatory response within the brain to the archetypal pro-inflammatory cytokines interleukin-1beta (IL-1beta) or tumour necrosis factor-alpha (TNF-alpha). We assessed how the cerebral vasculature changes with age and whether any structural alterations are associated with altered cytokine sensitivities. Six hours after equivalent microinjections of IL-1beta or TNF-alpha, 3-week-old juvenile and 18-month-old aged rats displayed increased leucocyte recruitment, blood-brain barrier (BBB) breakdown, and a loss of specificity in the populations of leucocytes recruited when compared with the restricted profile observed in 2-month-old young adult rat brain. The expression of the tight junction protein claudin-1 was absent in those vessels where neutrophils were being actively recruited. To determine whether changes in the structure of the BBB might be responsible for the increased susceptibility observed at either end of the age spectrum, we compared the number of claudin-1 positive vessels in the unchallenged brain to the total number of vessels. Virtually all vessels in the young adult brain express claudin-1, but a significant proportion of vessels are claudin-1 negative in the juvenile rat brain. In the aged rat brain, the overall number of vessels is markedly reduced, but the majority of these still appear to be claudin-1 positive. The pattern of claudin-1 expression together with the change in vessel density indicates that the properties of the BBB change with age, and, despite similarities, the underlying cause of the heightened inflammatory response in the juvenile and in the aged brain is likely to differ. Indeed, the spatial characteristics of the cytokine-induced BBB breakdown are different at either end of the age spectrum. These studies identify two periods within the lifespan of a rat where susceptibility to pro-inflammatory mediators is dramatically increased.

Coronary Artery Bypass Grafting is Superior to Percutaneous Coronary Intervention in Prevention of Perioperative Myocardial Infarctions During Subsequent Vascular Surgery

Among patients in need of coronary revascularization before an elective vascular operation, the value of coronary artery bypass grafting (CABG) versus percutaneous coronary intervention (PCI) in preventing perioperative myocardial infarctions is uncertain. We hypothesized that more complete revascularization would improve outcomes after vascular surgery. In this Veterans Affairs Cooperative trial involving 18 medical centers, 222 patients underwent elective vascular surgery after coronary revascularization. The mode of coronary revascularization was selected at each site by the local investigators (CABG in 91 patients and PCI in 131 patients). The vascular surgical indications were similar in both groups. There were 2 deaths in the CABG group (2.2%) and 5 deaths in the PCI group (3.8%; p = 0.497) after the vascular procedure. There were fewer perioperative myocardial infarctions after the vascular operation in CABG patients (6.6%) than in PCI patients (16.8%; p = 0.024), despite more diseased vessels in the CABG group (3.0 +/- 1.3 versus 2.2 +/- 1.4, respectively; p < 0.001). The completeness of revascularization (defined as the number of coronary artery vessels revascularized relative to the total number of vessels with a stenosis > or = 70%) in patients in the CABG and PCI groups was 117% +/- 63% and 81% +/- 57%, respectively (p < 0.001). Hospital length of stay in CABG versus PCI patients was 6 (4, 8) and 7 (4, 10) days, respectively (p = 0.078). Among patients receiving multivessel coronary artery revascularization as prophylaxis for elective vascular surgery, patients having a CABG had fewer myocardial infarctions and tended to spend less time in the hospital after the vascular operation than patients having a PCI. More complete revascularization accounted for the intergroup differences.

CHARACTERIZATION OF CANINE SUPERFICIAL TUMORS USING GRAY‐SCALE B MODE, COLOR FLOW MAPPING, AND SPECTRAL DOPPLER ULTRASONOGRAPHY—A MULTIVARIATE STUDY

Superficial tumors are not routinely evaluated by two- or three-dimensional diagnostic imaging methods as part of the staging of canine cancer patients, although superficial tumors are readily imaged by ultrasound. The objectives of this study were to characterize the ultrasonographic patterns of superficial tumors and to evaluate whether ultrasound can help discriminate between benign and malignant tumors in dogs. Superficial tumors (n=132) in 86 dogs were evaluated by B mode, color flow mapping, and spectral Doppler ultrasonography. Size, echogenicity, tumor border definition, invasiveness, acoustic transmission, presence and distribution of vascular flow to and within the tumor, as well as perfusion indices were measured. The tumors were classified as lipomas, benign tumors, atypical mammary tumors, and malignant tumors. Multivariate statistics using discriminant analysis was used to determine which parameters may be used to predict the status of the tumor. Tumor echogenicity, border shape, acoustic shadowing, total number of vessels to the tumor and the total flow amount are the parameters that in combination resulted in the lowest classification error (24%), meaning that on average three out of four tumors were correctly classified using these parameters. All the lipomas and atypical mammary tumors were classified correctly by ultrasonography. The results of this study show that ultrasonography has an important role in the evaluation of canine superficial tumors, particularly in the evaluation of tissue homogeneity and tumor vascularity.

Pancreatic carcinoma versus chronic focal pancreatitis: contrast-enhanced power Doppler ultrasonography findings

We assessed the potential usefulness of contrast-enhanced power Doppler ultrasonography (US) for differentiating pancreatic carcinoma from chronic focal pancreatitis. Twenty-six consecutive patients with ductal carcinoma (n=16) and chronic focal pancreatitis (n=10) underwent power Doppler US examinations before and after intravenous injection of an air-based contrast agent (Levovist, Schering, Berlin, Germany). Final diagnosis was obtained by surgery in all patients. The following parameters before and after intravenous administration of contrast agent were evaluated for each lesion: number, morphology and course of the vessels within the lesion and time to maximum detectable enhancement. Number of the lesion vessels and time to maximum enhancement for each lesion were compared by with Student t test. After injection of contrast agent, nine of 16 (56.2%) carcinomas showed a larger total number of vessels (p<0.005) and faster enhancement (p<0.0001) compared with chronic focal pancreatitis. Irregular vessels with a serpiginous course that penetrated the tumor was predominant in carcinoma (eight of 16 cases), whereas focal pancreatitis presented mostly as avascular masses (five of 10 cases). Contrast-enhanced power Doppler US provides useful findings for differentiating pancreatic carcinoma from chronic focal pancreatitis.

Clinical Response, Vascular Change, and Angiogenesis in Gonadotropin-Releasing Hormone Analogue-Treated Women with Uterine Myomas

Basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) are involved in the pathogenesis of leiomyomas and influence angiogenesis, which is necessary for growth of leiomyomas. Gonadotropin-releasing hormone analogue (GnRH-a) treatment might modify the growth factor expression and the blood supply in myomas. We investigated the effects of GnRH-a treatment on some clinical parameters, on the immunohistochemical expression of bFGF, VEGF, and PDGF, and on the vasculature of leiomyomas. Thirty-one women were treated with leuprolide acetate for 3 months; 55 untreated patients formed the control group. Hematologic parameters were assessed at the admission, after GnRH-a treatment, and after surgery. Uterine volume was evaluated by ultrasonography. The immunoexpression of bFGF, VEGF, and PDGF and of the endothelial markers CD34 and CD105, as well as the vascular pattern, were studied in leiomyomas, comparing treated and untreated patients. Hematologic parameters improved and uterine volumes decreased after GnRH-a treatment. The immunoexpression of bFGF, VEGF, and PDGF decreased in treated myomas, together with the total number of vessels and the angiogenetic vessels. This study confirms the clinical response of uterine shrinkage after GnRH-a treatment. A pathogenetic role of bFGF, VEGF, and PDGF in myoma growth and vascularization is suggested. Finally, this study indirectly confirms the importance of the vasculature in leiomyoma growth.

Progressive loss of endothelial P-selectin expression with increasing malignancy in colorectal cancer

Adhesion of inflammatory cells to vascular endothelium is mediated by specific cell adhesion receptors on both leukocytes and endothelial cells. One of the adhesion molecules on the endothelium is P-selectin. Decreased vascular P-selectin expression has been associated with tumor progression in melanoma patients. We now report on the expression of endothelial P-selectin in colorectal cancer (CRC). We studied a colorectal tissue specimen series ranging from normal colorectal tissue via unmetastasized primary tumors to tumors with the same depth of invasion at the primary site but with liver metastases. Moreover, P-selectin expression levels in liver metastases were determined. The number of P-selectin positive vessels as a fraction of the total number of vessels, both intra- and peritumorally, was determined by staining for CD62P and CD34, respectively. Furthermore, by immunostaining for leukocytes (CD45) and macrophages (CD68), it was evaluated whether levels of P-selectin expression influenced infiltrate density and composition. The results showed that levels of peritumoral P-selectin expression were reciprocal to the degree of progression in CRC. This relation was even more pronounced intratumorally: in metastasized primary tumors and in the metastatic lesions, P-selectin expression was virtually absent. This distribution pattern was reflected in the numbers of leukocytes that accumulated in the various tissues, since in the primary tumors with metastases, and in the metastatic lesions, hardly any infiltrating cells were observed. In these lesions, leukocytes were present in the peritumoral zone, but seemed unable to enter the tumor tissue. In primary tumors without metastasis, the intratumoral leukocyte infiltration density was significantly higher. Recruitment levels of macrophages remained constant throughout the different tissues. We suggest that downregulation of endothelial P-selectin expression is a mechanism by which CRC lesions evade inflammatory regression and, thereby, progress to a more advanced stage of malignancy.

Increased Angiogenesis and Expression of Vascular Endothelial Growth Factor during Scarless Repair

Vascular endothelial growth factor (VEGF) is a dimeric heparin-binding glycoprotein that is a potent endothelial cell-specific mitogen with increased expression during adult cutaneous wound healing. VEGF activity is mediated by two receptors, VEGFR-1 (Flt-1) and VEGFR-2 (Flk-1/KDR), which are expressed primarily in vascular endothelial cells. Initiation of profibrotic cytokine expression likely coordinates the transition from scarless healing to scar formation in fetal wounds. Angiogenesis is an important component of the scarring repair process, but the function of VEGF and degree of angiogenesis during scarless repair has not been investigated. We hypothesize that VEGF and its receptors are differentially expressed in scarless compared with scarring fetal wounds because VEGF is implicated in angiogenesis during skin development and adult wound healing. Excisional wounds were created on fetal rats at gestational ages 16.5 days (E16) and 18.5 days (E18) (term = 21.5 days). Wounds were harvested at 24 and 72 hours (n = 12 wounds per time point). Nonwounded fetal skin (E17, E19, and E21) was used as control. Reduced-cycle, specific-primer, reverse-transcriptase polymerase chain reaction was performed to determine the expression of VEGF and its receptors, VEGFR-1 and VEGFR-2. Wounds at 72 hours and fetal skin controls were examined under high-power microscopy for blood vessel counts. Unpaired two-tailed t test was used (p < 0.05 was considered significant). VEGF expression increased 2.4-fold (p < 0.001) during normal skin development from E17 to E19. In scarless wounds (E16), VEGF expression increased 2.8-fold (p < 0.02) at 72 hours. No increased expression occurred in the scarring wounds (E18). VEGFR-1 and VEGFR-2 expression increased over 2-fold during normal skin development from E17 to E21. However, each was down-regulated 30 to 50 percent in scarless (E16) and scarring (E18) wounds. There is a 2-fold increase in mean vessel counts per high-power field in scarless (E16) wounds at 72 hours compared with age-matched control skin (p < 0.02) and a 1.7-fold increase in mean vessel count in scarring fetal wounds (E18) compared with age-matched control skin (p < 0.05). There is no difference in the total number of vessels found in scarless versus scarring wounds or between 19.5-day versus 21.5-day fetal skin. VEGF and its receptors, VEGFR-1 and VEGFR-2, increase expression during skin development and dermal differentiation. VEGF expression quickly elevates during scarless compared with scarring repair, which likely contributes to the more rapid scarless fetal repair rate. Similar numbers of new ves-sels are formed during scarless and scarring fetal repair.

Metastatic and Inflammatory Cervical Lymph Nodes as Analyzed by Contrast-Enhanced Color-Coded Doppler Ultrasonography: Quantitative Dynamic Perfusion Patterns and Histopathologic Correlation

Use of contrast-enhanced color-coded Doppler (ultra)sonography (CCDS) in evaluating enlarged lymph nodes has been subject to numerous attempts to define criteria for differentiation between benign and malignant lesions. Evaluation of dynamic perfusion patterns with contrast-enhanced CCDS in cervical lymph nodes offers new possibilities of differential diagnosis. A total of 28 patients with clinically enlarged lymph nodes were included in this study. Contrast-enhanced CCDS was performed on each patient. The color signals from nodes <15 mm in diameter were analyzed with a specialized computer program. Each node was later examined through immunohistochemical staining. Vascularization as shown by unenhanced CCDS was significantly greater in metastatic lymph nodes than in reactively enlarged lymph nodes (8.66% versus 2.81%; p = .01). The maximum vascularization area after contrast injection did not show any significant change (26.61% versus 28.63%; p = .75). Comparison of values obtained before and after contrast enhancement showed the largest relative increase in vascularization in inflammatory lymph nodes, from a factor of 19.55 to a factor of 10.03 (p = .025). Dynamic values such as contrast enhancement, behavior of dynamic values referred to time, and the evaluated vascularized area did not show any significant difference. The metastatic lymph nodes (5.46 versus 3.33; p = .007) predominantly consisted of large blood vessels. The increased vascularization in the unenhanced CCDS examination of metastatic lymph nodes seems to be associated with the increased number of large blood vessels. An increased vessel density, due to a greater number of total vessels, is related to an inflammatory process. Color Doppler mapping has been proven to depict useful aspects distinguishing benign from malignant lymph nodes of the neck; however, a definitive differentiation between lymph nodes involved with malignancy and inflammatory changes remains difficult.

MICROCIRCULATION ASSOCIATED WITH DEGENERATIVE ROTATOR CUFF LESIONS

Diminished vascular supply is associated with degenerative rotator cuff lesions. Orthogonal polarization spectral imaging allows noninvasive assessment of microcirculation without application of fluorescent contrast medium. The aim of our study was to visualize and quantify in vivo the microcirculation of the rotator cuff during arthroscopic surgery and to compare the results with the number of microvessels identified in vitro by immunostaining of biopsy specimens taken from the scanned areas. Eleven patients with clinical signs of a degenerative rotator cuff lesion were studied. Prior to arthroscopic subacromial decompression, the superficial part of the supraspinatus tendon at the edge of the lesion as well as the unaffected tendon insertion was examined. Microvascular parameters established for the description of tissue perfusion with use of conventional intravital fluorescence microscopy (functional capillary density and capillary diameter) were assessed in vivo. Biopsy specimens were taken from the scanned areas, and the microvessels were localized by immunostaining for the endothelial surface marker CD31. In the region of the unaffected tendon insertion, the mean baseline functional capillary density (and standard deviation) was 106 +/- 13 cm/cm(2) and the mean capillary diameter was 10 +/- 0.7 microm. In contrast, at the edge of the lesion, the functional capillary density was significantly reduced to 20 +/- 14 cm/cm(2), whereas the diameter of the vessels that were present did not differ. The total number of vessels stained in vitro was also significantly reduced at the edge of the lesion compared with the number of vessels in the tendon insertion zone. Quantitative in vivo analysis of human microcirculation during arthroscopy demonstrated that the functional capillary density at the edge of a degenerative rotator cuff lesion was significantly reduced compared with that in the control tissue. The capacity to assess microcirculatory flow in vivo may help to identify specific repair strategies based on knowledge of individual perfusion patterns.

Fusion of Radar Tracks, Reports and Plans

This paper suggests a method that utilizes non-real time information as an aid to improve maritime surveillance. Under certain conditions vessels move in accordance with preplanned routes and possibly also report their own position at certain positions or at certain times during the voyage. The method proposed consists of a statistical route model that describes the movement of the vessel, and includes refinement of the estimated movement based upon reports on the vessel. The estimated movement is then associated with radar tracks using multiple hypothesis techniques. This is due to the fact that the number of vessels with known route plans is small compared to the total number of vessels in an area. The associated radar tracks are also used to improve the estimated movement of the vessels. The problem of generating possible solutions and selecting the best hypothesis is formulated as a constraint satisfaction problem and implemented using a constraint programming technique.

Dynamics of a fishery on two fishing zones with fish stock dependent migrations: aggregation and control

This work presents a specific stock-effort dynamic model. The stock corresponds to two fish populations growing and moving between two fishing zones, on which they are harvested by two different fleets. The effort represents the number of fishing vessels of the two fleets which operate on the two fishing zones. The bioeconomical model is a set of four ordinary differential equations governing the stocks and the fishing efforts in the two fishing areas. Fish migration, as well as vessels displacements, between the two zones are assumed to take place at a faster time scale than the variation of the stocks and the changes of fleets sizes, respectively. The vessels movements between the two fishing areas are assumed to be stock dependent, i.e. the larger the stock density is in a zone the more vessels tends to remain in it. The global fish stock and the total number of vessels keep constant at the fast time scale. This property enables, via aggregation methods, the reduction of the system dimension in order to proceed to its qualitative analysis. Under some assumptions, we obtain either a stable equilibrium or a stable limit cycle which involves large cyclic variations of the total fish stock and fishing effort. Finally, we introduce a control parameter to maintain the system at a sustainable equilibrium and thus avoiding the important fluctuations founded otherwise.

Inhibition of protein kinase Calpha prevents endothelial cell migration and vascular tube formation in vitro and myocardial neovascularization in vivo.

Although protein kinase C (PKC) activation is required for endothelial cell (EC) growth, migration, adhesion, and vessel formation, the role of individual PKC isoenzymes in these events is not defined. Because PKCalpha has been previously linked with enhanced EC migration and response to angiogenic growth factors, we characterized a specific phosphorothioate-modified 21-mer antisense PKCalpha (AS-PKCalpha). AS-PKCalpha (500 nmol/L) prevented the expression of PKCalpha protein by 90% in human ECs and did not reduce the expression of any other PKC isoenzyme. AS-PKCalpha reduced human EC migration by 64% compared with its control oligonucleotide in a "scratch" wounding assay, and AS-PKCalpha reduced human EC adhesion to the extracellular matrix protein vitronectin by 18%. Phosphorylation of mitogen-activated protein kinase (extracellular signal-regulated kinase 1/2) induced by vascular endothelial growth factor was inhibited by 30% in human ECs transfected with AS-PKCalpha. Compared with control, AS-PKCalpha also reduced the number of EC tubes formed in a 3D type I collagen gel assay by 37.5%. Finally, using an osmotic minipump, we infused AS-PKCalpha into mice in which myocardial infarction was induced by coronary ligation and found that the oligonucleotide was primarily taken up by intramyocardial blood vessels. Compared with the results with control oligonucleotide, AS-PKCalpha oligonucleotide inhibited the number of anti-PKCalpha-stained blood vessels by 48% and reduced the total vessel number by 72% as well. In conclusion, the expression of PKCalpha is required for full EC migration, adhesion to vitronectin, vascular endothelial growth factor-induced extracellular signal-regulated kinase activation, and tube formation and is likely to be of importance in myocardial angiogenesis in vivo after ischemia.

Numerical Simulations of Angiogenesis in the Cornea

Angiogenesis plays important roles in many physiologic and pathologic processes in the body. To understand mechanisms of angiogenesis, we developed a mathematical model for quantitative analysis of various biological events involved in angiogenesis. Our model was focused on two-dimensional angiogenesis in the cornea. The model considered diffusion of angiogenic factors, uptake of these factors by endothelial cells, and randomness in the rate of sprout formation and the direction of sprout growth. Our simulation results indicated that redistribution and uptake of angiogenic factors during angiogenesis had significant effects on the structure of vascular networks. A decrease in the uptake rate resulted in increases in vessel density, self-loop formation, and front migration speed of vascular networks. The randomness in the direction of sprout formation determined the curvature of vessels, whereas the probability of sprout formation from a vessel segment had a significant effect on the total number of vessels in vascular networks. The vascular networks generated in numerical simulations were similar to those observed experimentally. The mathematical model developed in this study can be used to evaluate effects of individual factors on angiogenesis, understand mechanisms of interactions among different factors during angiogenesis, and generate experimentally testable hypotheses.

Quantitative Assessment of Angiogenesis and Tumor Vessel Architecture by Computer-Assisted Digital Image Analysis: Effects of VEGF–Toxin Conjugate on Tumor Microvessel Density

Tumor growth is angiogenesis dependent. As a consequence, strategies aimed at disrupting this mechanism are heavily investigated. Several angiogenesis assays are used to directly compare the efficacy of anti-angiogenic compounds. However, objective assessment of new vascular growth has been difficult to achieve. The aim of this study was to test and develop a computer-assisted image analysis method that would give an unbiased quantification of the microvessel density. Human tumors were grown in athymic mice and tumor biopsies were taken after a weeklong treatment with VEGF–toxin conjugate. Frozen tumor sections were prepared and stained with PE-conjugated anti-CD-31 antibodies and vessels were imaged with a fluorescence microscope. Vessel density was analyzed by quantifying PE-positive pixels per recorded field. In addition, images were further processed to investigate morphological differences by an automated binarization and skeletonization protocol. This procedure allowed the computer-assisted estimation of important angiogenic parameters such as total vessel number, length, and branch points. Based on these indices, differences in the angiogenic response between control tumors and those treated with VEGF–toxin conjugate were readily detected (P < 0.007 for all parameters). More importantly, computer-generated measurements correlated well with manual microvessel counts and showed significantly less variation. Our results suggest that computer-assisted image analysis represents a rapid, objective, and alternative method for the quantitative assessment of tumor angiogenesis and vessel architecture.

Histologic evidence that basic fibroblast growth factor enhances the angiogenic effects of transmyocardial laser revascularization.

To determine whether addition of basic fibroblast growth factor (bFGF), an angiogenic growth factor, enhances the angiogenic effects of transmyocardial laser revascularization (TMR). TMR is an investigational therapy for treating patients with medically refractory angina not amenable to traditional therapies. Histologic and blood flow studies in animals have suggested that TMR enhances angiogenesis above that normally seen in ischemic myocardium. We tested the hypothesis that bFGF administered into TMR channels further enhance the angiogenic effects of TMR. Chronic ischemia was created in 3 groups of dogs using an ameroid constrictor on the proximal LAD. In the bFGF group (n = 5) non-transmyocardial channels were created in the LAD territory and bFGF, (100 ng/ml) dissolved in pluronic gel was injected into the each channel. In the TMR group (n = 7), transmyocardial channels were created without bFGF. A control group (n = 7) had ischemia without TMR of bFGF. 5-bromo-2'-deoxyuridine (BrdU) was administered to mark proliferating cells. After 8 weeks survival, colored microspheres were injected to assess the regional myocardial blood flow. TMR and TMR+bFGF increased total vascular density by approximately 40% over that observed in the control group. However, the number of large vessels (internal diameter > or = 50 microm) was doubled by the addition of bFGF, and this correlated with a 50% increase in the density of proliferating vascular cells and a tripling of the total estimated vascular cross sectional area. Blood flow to the LAD territory was increased by TMR compared to controls, with no further benefit observed in the bFGF group. On a histologic basis, basic fibroblast growth factor further enhances angiogenesis following TMR in ischemic myocardium mainly by increasing the size but not the total number of vessels.

Relationship of vascular maturation in breast cancer blood vessels to vascular density and metastasis, assessed by expression of a novel basement membrane component, LH39.

Angiogenesis, the formation of new vessels, has been demonstrated to be an indicator of prognosis in breast cancer patients. The extent of differentiation of the tumour vessels may affect access of peripheral white cells and egress or invasion of tumour cells. This has not been assessed in relation to tumour microvessel density or other variables and may be a marker of vascular remodelling. LH39 is a monoclonal antibody recognizing an epitope located at the lamina lucida of mature small veins and capillaries but not in newly formed vessels. To study vascular differentiation in breast tumours, we examined the vascular maturation index (VMI) in 12 normal and 50 breast carcinomas and this was correlated with different clinicopathological variables including angiogenesis. Mature vessels were defined by staining with antibodies to both LH39 and to CD31, using double immunohistochemistry, whereas immature vessels stained only for CD31. VMI was defined as the % fraction of mature vessels (LH39-positive) / total number of vessels (CD31-positive). The VMI was significantly higher in normal (54–68.5%; median 66.5%) than in tumours (0–47%; median 8.8%) (P = 0.0005). There was a significant inverse correlation between the tumour VMI and nodal status (Fisher's exact test, P = 0.01) and between high VMI and low thymidine phosphorylase (TP) expression (Mann–Whitney U -test, P = 0.01). No significant association between VMI and tumour size, oestrogen receptor, epidermal growth factor receptor, grade, angiogenesis, patient age, or E-selectin was seen. There was a significant reduction in relapse-free survival (P = 0.01) with high angiogenesis. These findings show that the VMI gives new information on the mechanism of tumour angiogenesis independently from microvessel quantitation, there is a wide variation in the differentiation of tumour vasculature but the degree of capillary differentiation is not associated with quantitative angiogenesis. The VMI identifies a subset of patients who have a high chance of regional node involvement. © 2000 Cancer Research Campaign

Clinicopathologic Growth Factors in Vestibular Schwannomas: a Morphological and Immunohistochemical Study of 69 Tumours

Tumour growth of vestibular schwannomas is still difficult to predict. The aim of our study was to determine whether any defined histopathological feature was correlated with the clinical course. We did a retrospective study with 69 paraffin-embedded tumours to establish whether the number of vessels, blood cells extravasation or degree of inflammation, all semi-quantitatively assessed, could be indicative of potential of growth. An immunohistochemical study was also performed with an endothelial marker CD34, the leukocyte common antigen CD45 and the estrogen and progesterone hormone receptors. All these parameters were correlated with patient's age, duration of symptoms (d), with a clinical growth index (CLI = tumour size/d). No clinical parameters proved to be predictive of tumour growth. Tumour size was significantly (p = 0.01) related to the number of vessels and we found a significant relationship between the clinical growth index (CLI) and total number of vessels, especially when duration of symptoms lasted less than 1 year (p < 0.001). However, we found no relationship between duration of symptoms or CLI and CD34 index. The degree of inflammation was significantly correlated (p = 0.007) with duration of symptoms when it lasted more than 1 year. The CD45 index and the semi-quantitative evaluation of the inflammation were well correlated (p = 0.001). No estrogen receptors antigenic site was detected and only seven tumours expressed progesterone receptor in a few cells without any significant clinical value. These results suggest that vessel density is determinant for sporadic acoustic neuroma growth especially for a short clinical course.

The development of neovascularisation in flap prefabrication with vascular implantation an experimental study

Femoral arteriovenous pedicles were implanted beneath the abdominal skin in rats ( n = 30) to investigate the development of neovascularisation over time. New vessel formation was assessed by micro-angiography and quantified under light microscopy. Flap viability was assessed by dye injection studies at different time intervals. Two weeks after implantation of the vascular pedicles, neovascularisation was confined to the vicinity of the arteriovenous pedicle only and none of the flaps were viable. At 4 and 6 weeks, 4 out of 6 flaps were viable, with new vessel formation being widespread throughout the subcutaneous tissue. All flaps were viable at 8 and 12 weeks. Neovascularisation in the dermis up to the epidermis was observed after 8 weeks. Neovascularisation in the panniculus carnosus showed a steady increase after 6 weeks. There was a decrease in the total number of vessels at 12 weeks compared to 8 weeks but at 12 weeks the diameters of the vessels were considerably larger. Flap survival was best predicted by the amount of neovascularisation in the panniculus carnosus. In this experimental model, it is concluded that prefabricated flaps should be raised at 8 weeks instead of 4 or 6 weeks after the implantation of an arteriovenous pedicle, to reduce the risk of flap failure.

The Effect of the Delay Phenomenon on the Vascularity of Rabbit Abdominal Cutaneous Island Flaps

The beneficial effects of the delay phenomenon have been evaluated extensively and are widely known. However, no study has quantified the vascular changes seen in an abdominal cutaneous island flap following a surgical delay by vascular pedicle ligation. We evaluated the effect of unilateral superficial inferior epigastric and deep inferior epigastric pedicle ligation on the vascularity of a rabbit abdominal cutaneous island flap. Thirty rabbits underwent a left superficial inferior epigastric and deep inferior epigastric pedicle ligation as a delay procedure. A 19 x 15 cm abdominal cutaneous island flap was elevated at the time of sacrifice, based solely on the right superficial inferior epigastric pedicle. The flap vasculature was then evaluated by methylene blue injection and lead oxide microangiography at 0, 5, 10, 15, 21, and 27 days following the delay procedure. Methylene blue studies revealed perfusion of only the right (nonligated) side of the flap on day 0 and perfusion of the entire flap by day 15. This "capture" of the left (ligated) superficial inferior epigastric artery angiosome by day 15 could only have been achieved through enhanced cross-midline perfusion. Lead oxide microangiography revealed an increase in the number of vessels from day 0 to day 27 on both the ligated and nonligated sides in all the following: the number of large "choke" vessels (> 0.5 mm) crossing the flap midline, total number of vessels (all sizes) crossing the flap midline, and total number of vessels (all sizes) at the medial aspect of the right and left superficial inferior epigastric artery angiosomes. A statistically significant increase in these vessels was not seen until day 21. The effect of the delay phenomenon was significantly greater on the ligated side compared with the nonligated side. The areas of the flap that were relatively more ischemic following left superficial inferior epigastric pedicle ligation (medial aspect of the caudad half of the left superficial inferior epigastric artery angiosome) showed greater increases in vascularity with the delay procedure than did areas of lesser ischemia (medial aspect of the cephalad half of the right superficial inferior epigastric artery angiosome).

The effect of the delay phenomenon on the vascularity of rabbit rectus abdominis muscles.

The transverse rectus abdominis muscle (TRAM) flap has become the "gold standard" for autogenous breast tissue reconstruction. Complications are reported in 10 to 40 percent of patients undergoing this procedure, and many are related to soft-tissue necrosis secondary to ischemia. Various methods have been proposed to improve TRAM flap survival, including surgical delay of the flap. The beneficial effects of the delay phenomenon have been well established in laboratory studies and clinical evaluations. Many investigators agree that the delay phenomenon will enhance arterial inflow and venous outflow from the TRAM flap. No study has quantified the changes seen in the rectus abdominis muscle following a delay procedure. In this prospective, controlled, and blinded experiment, we evaluate the effect of a unilateral superficial inferior epigastric and deep inferior epigastric artery and vein ligation on the vascularity of the rectus abdominis muscles in rabbits. Thirty-eight rabbits underwent a left superficial inferior epigastric and deep inferior epigastric pedicle ligation as a delay procedure. The rectus abdominis muscle vasculature was then evaluated by lead oxide microangiography at 0, 5, 10, 15, 21, and 27 days following the delay procedure. Magnification (x 2) was used to count the number of vessels at the periphery of the deep inferior epigastric artery angiosomes in the microangiograms. An increase in the number of vessels from day 0 to day 27 was seen on both the ligated and nonligated sides in all the following: the number of large (> 0.5 mm) "choke" vessels and total number of vessels (all sizes) crossing the abdominal wall midline and the total number of vessels (all sizes) at the medial, superior, and lateral aspects of the right and left deep inferior epigastric artery angiosomes. A statistically significant increase in these vessels was not seen until day 21. The effect of the delay phenomenon was significantly greater on the ligated side compared with the nonligated side. The areas of the rectus abdominis muscles that were relatively more ischemic following left deep inferior epigastric pedicle ligation (medial aspect of the left deep inferior epigastric artery angiosome) showed greater increases in vascularity with the delay procedure than did areas of lesser ischemia (lateral aspect of the right deep inferior epigastric artery angiosome).