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PubMed1991

L-cysteine selectively potentiates nitroglycerin-induced dilation of small coronary microvessels.

Nitroglycerin potently dilates large coronary arteries but has minimal effect on coronary resistance vessels. Thus, nitroglycerin is not likely to be converted to vasoactive intermediates in small coronary microvessels (less than 100 microns diameter). Because nitroglycerin biotransformation may involve sulfhydryl groups, the effect of L-cysteine on the dilation caused by nitroglycerin (1 nM to 10 microM) was examined in small (80-100 microns in diameter) and large (190-300 microns in diameter) porcine coronary microvessels. Vessels were pressurized in a no-flow state and preconstricted with acetylcholine, then visualized by means of an in vitro microvessel imaging apparatus. Under control conditions, nitroglycerin caused potent dilations of large coronary microvessels, while having minimal effects on small coronary microvessels [peak relaxations 90 +/- 3 vs. 20 +/- 7% (mean +/- S.E.M.) of preconstricted diameter, respectively]. L-Cysteine (100 microM) markedly enhanced relaxations of small coronary microvessels (peak relaxation 96 +/- 2%), while having no effect on relaxations of large coronary microvessels. Ethacrynic acid, which alkylates sulfhydryl groups, markedly inhibited relaxations of large coronary microvessels (peak relaxation = 31 +/- 9%) yet had a minimal effect on the small relaxations of small coronary microvessels to nitroglycerin. Thus, when sulfhydryl groups are made available, small coronary microvessels are markedly responsive to nitroglycerin. This suggests that small coronary microvessels normally lack the reductive capacity to convert nitroglycerin to its active metabolites. Prussian blue stains of sulfhydryl groups in large and small coronary microvessels were qualitatively similar. Thus, small coronary microvessels do not lack sulfhydryl groups but may be deficient in a critical pool necessary for nitroglycerin biotransformation.

Animals↗

PubMed2005

Quantitation of microvessel density in squamous cell carcinoma of the head and neck by computer-aided image analysis.

OBJECTIVE: Angiogenesis is the formation of new blood vessels from a preexisting vascular network. In healthy individuals it is normally suppressed and observed only transiently during development, reproduction and wound healing. However, growth, invasion, and metastasis of most solid tumors are dependent on angiogenesis. Without formation of new blood vessels, also termed as neovascularization, tumors cannot exceed a size of about 1 mm3. Therefore, neovascularization is a basic requirement for nutrition and oxygenation of tumor cells. Numerous studies in different solid as well as non-solid tumors have evaluated the prognostic value of tumor neovascularization. In solid tumors the increased microvessel density, the pathological correlate to tumor neovascularization, has been linked to a worse prognosis of the disease. The aim of the current study was to assess the prognostic value of tumor neovascularization for recurrences in squamous cell carcinoma of the head and neck by determining microvessel density. Data was collected using an automated-computerized method and as well as a manual counting method. BASIC RESEARCH DESIGN: Immunohistochemistry was performed to detect intratumoral microvessels in tumor samples of 50 patients with squamous cell carcinoma of the head and neck. We used a monoclonal mouse antibody directed against the CD34 antigen. After immunostaining, the entire tumor section was scanned microscopically at low power (x 40) to identify hot spots, which are the areas of highest neovascularization. Individual tumor microvessels were then counted under high power (x 200) to obtain a vessel count in a defined area, and the average vessel count in 4 hot spots was taken as the microvessel density. Microvessel counting was performed twice by computerized method, as well as manually by two independent investigators without any previous knowledge of patients' pertinent clinical data. Subsequently, both counting techniques were statistically compared with each other. RESULTS: On computer-aided image analysis an increased microvessel density was significantly correlated with recurrence of disease (p = 0.02). Repetitive computer counts yielded similar results (p = 0.08), whereas repeated manual counts by two investigators varied significantly (p = 0.04). However, no further statistical correlations between microvessel density and patients clinical data i.e. tumor status, lymph node status, overall survival, or disease free interval could be found. Furthermore, estimation of overall survival of patients with an increased microvessel density by Kaplan-Meier curves revealed non-significant results. CONCLUSION: There is mounting evidence that suggests, that assessment of tumor neovascularization might provide a novel approach of prognostication in patients with squamous cell carcinomas of the head and neck. In particular, in the present study, the degree of angiogenesis of a tumor, as assessed by microvessel density, was found to be correlated with recurrent disease in squamous cell carcinoma of the head and neck. Computer aided image analysis, an automated technique, constitutes a time-efficient and reproducible technique for quantification of tumor vascularization. We suggest that this computerized microvessel determination could be used as a reliable method for microvessel counts, which, furthermore, seems to be superior to manual counting. However, for a reliable and reproducible assessment of tumor neovascularization, validation procedures and quality control protocols are mandatory.

Adult↗

PubMed1991

Role of the endothelium in modulation of the acetylcholine vasoconstrictor response in porcine coronary microvessels.

STUDY OBJECTIVE: The aim was to investigate the role of the endothelium in modulating the acetylcholine response in porcine coronary microvessels and compare the results with simultaneously studied large coronary arteries. DESIGN: Coronary microvessels [104 (SEM 3.3) microns; range 38-150] were removed from fresh porcine hearts and studied in vitro during no flow constant pressure conditions. Endothelium derived relaxing factor (EDRF) activity and the role of the endothelium in modulating the acetylcholine response in microvessels was assessed by measuring changes in intraluminal diameter using a video tracking device. Large coronary arteries were simultaneously studied using conventional isometric ring techniques. EXPERIMENTAL MATERIAL: Fresh porcine hearts were obtained from a local slaughterhouse. MEASUREMENTS AND MAIN RESULTS: Acetylcholine was a potent vasoconstrictor (EC50 = 0.17 microM) of passively distended microvessels. The effects of EDRF were studied by either inactivation with haemoglobin or inhibition of EDRF synthesis with N-omega-nitro-L-arginine. Preconstricted microvessels exposed to either N-omega-nitro-L-arginine or haemoglobin constricted further, consistent with basal release of EDRF. Neither drug affected passively distended microvessels. The acetylcholine vasoconstrictor response was potentiated after exposure of microvessels to either drug. Atropine, but not indomethacin, blocked the acetylcholine response in microvessels. As with microvessels, acetylcholine was a vasoconstrictor (EC50 = 0.3 microM) of large coronary arteries. In contrast to microvessels, indomethacin antagonised acetylcholine vasoconstriction in vessels with intact endothelium. Bioassay experiments using indomethacin-treated large epicardial donor artery segments showed basal release of EDRF but no EDRF release in response to acetylcholine. CONCLUSIONS: The results show the microvessels and large coronary arteries are similar in their vasoconstrictor response to acetylcholine, that both release EDRF basally, and that vasoconstriction to acetylcholine is importantly modulated by the endothelium. In large arteries, acetylcholine does not stimulate EDRF release and, in contrast to microvessels, a cyclo-oxygenase product influences the vasoconstrictor action of acetylcholine.

Acetylcholine↗

PubMed1998

cGMP modulates basal and activated microvessel permeability independently of [Ca2+]i.

To investigate the mechanisms whereby guanosine 3',5'-cyclic monophosphate (cGMP) modulates microvessel permeability in vivo, we measured changes in microvessel hydraulic conductivity (Lp) and endothelial cytoplasmic Ca2+ concentration ([Ca2+]i) in response to the cGMP analogs 8-bromo-cGMP (8-BrcGMP) and 8-(p-chlorophenylthio)cGMP (8-pCPT-cGMP) in the presence and absence of inflammatory stimuli in intact individually perfused microvessels in frog and rat mesenteries. The cGMP analog caused a transient increase in Lp and potentiated ATP or bradykinin-induced increases in Lp in frog and rat mesenteric microvessels, respectively. The mean peak value of the test Lp/control Lp after exposure to 8-BrcGMP was 5.3 +/- 0.5 in frog microvessels and 2.8 +/- 0.4 in rat microvessels. The ATP-induced increase in Lp in frog microvessels was further raised by 8-BrcGMP from 7.0 +/- 0.9 to 12.4 +/- 1.9 times the control. In rat mesenteric microvessels, the bradykinin-induced increase in Lp was potentiated by 8-BrcGMP from 4.8 +/- 0.4 to 8.3 +/- 1.3 times the control and was suppressed by the guanylate cyclase inhibitor LY-83583 to 2.6 +/- 0.5 times the control. A similar but larger effect was found when using 8-pCPT-cGMP. In contrast to the actions of increased cGMP on microvessel permeability, cGMP analogs had no effect on basal endothelial [Ca2+]i and did not alter the magnitude and time course of ATP or bradykinin-induced increases in endothelial [Ca2+]i. These results suggested that an elevation of cGMP levels in endothelial cells is a necessary step to increase microvessel permeability in intact microvessels, and this regulatory process occurs downstream from Ca2+ influx, which differs from that reported in large-vessel endothelium in culture and in vascular smooth muscle cells. Experiments carried on microvessels in both frog and rat mesenteries provided a direct comparison of the endothelial cell regulatory mechanisms between species.

Adenosine Triphosphate↗

PubMed2000

Microvessels that predict axillary lymph node metastases in patients with breast cancer.

HYPOTHESIS: The density of vasoactive endothelial growth factor receptor 3-immunostained microvessels in primary breast cancers correlates with the incidence of axillary lymph node metastasis. DESIGN: Breast cancer microvessel clusters ("hot spots") were sequentially immunostained for factor VIII, type IV collagen, and vasoactive endothelial growth factor receptor 3. Microvessels were counted under light microscopy at a magnification of x 200. Axillary lymph nodes were evaluated for metastases by light microscopy. SETTING: A multidisciplinary breast cancer clinic and laboratory. PATIENTS: Sixty patients with T2 breast cancers treated by lumpectomy (or mastectomy) and axillary lymphadenectomy. MAIN OUTCOME MEASURES: Putative lymphatic microvessel density compared with axillary metastases. RESULTS: There were 16% (SE, 1.4%) vs 4% (SE, 0.8%) vasoactive endothelial growth factor receptor 3-immunostained microvessels (P<.001), 38% (SE, 3.9%) vs 65% (SE, 3.1%) type IV collagen-immunostained microvessels (P<.001), and 46% (SE, 4.1%) vs 31% (SE, 3.2%) unstained microvessels (P = .004) in node-positive vs node-negative patients, respectively. A fitted logistic model based on the relative percentage of putative lymphatic microvessels to blood microvessels correctly predicted that 23 (96%) of 24 patients would have a low risk and that 26 (96%) of 27 patients would have a high risk of lymph node metastases. Six (67%) of 9 patients predicted to have an intermediate risk had lymph node metastases. CONCLUSION: The odds of a patient with breast cancer having axillary lymph node metastasis increased substantially as the proportion of putative lymphatic microvessels increased and the relative proportion of blood microvessels in angiogenic hot spots decreased (log likelihood = 14.6; chi2 = 53.4; P<.001; area under the receiver operation characteristic curve = 0.97).

Breast Neoplasms↗

PubMed1998

Prostate cancer microvessels: a novel method for three-dimensional reconstruction and analysis.

BACKGROUND: Studies of prostate cancer microvessels to date have relied on routine two-dimensional images from histologic tissue sections, and there have been no previous reports of three-dimensional (3D) reconstruction and analysis of prostatic microvessels in benign or malignant specimens. Knowledge about the 3D architecture of microvessels would be useful for determining the utility and limitations of two-dimensional (2D) measures, as well as for determining the usefulness of 3D measures to predict pathologic stage and patient outcome in prostate cancer. However, the ability to study microvessels in 3D must first be demonstrated. METHODS: We developed a novel method to visualize and analyze prostate microvessels in three dimensions from serially-sectioned prostate specimens, including tissue preparation, reconstruction of serial histologic sections into 3D volumes, extraction of vessels from this data set, and calculation of geometric characteristics. Eleven regions of benign and cancer tissue were studied and compared in an effort to validate our methodology. RESULTS: Microvessels and glandular elements from benign and malignant tissue were visualized together in three dimensions. In the 3D visualizations, microvessels associated with cancer were seen to have more arbitrary pathways, increased tortuosity, and a more casual relationship with glandular elements than microvessels associated with benign tissue. A quantitative measure, the volume length density, discriminated between benign tissue and cancer better than simple microvessel density in this exploratory study. CONCLUSIONS: Microvessels in prostate cancer have a more homogeneous distribution and greater tortuosity than those in benign tissue. Volume length density of microvessels shows promise as a 3D marker in prostate cancer.

Adenocarcinoma↗

PubMed1979

Cerebral microvessels and derived cells in tissue culture: isolation and preliminary characterization.

Microvessels isolated from mouse forebrain were used as the source material for the derivation of cerebral vascular endothelium and smooth-muscle cells in culture. The microvessels were isolated by a mechanical dispersion and filtration technique, and were maintained in vitro as organoid cultures. A microvessel classification system was developed and proved to be useful as a tool in monitoring culture progress and in predicting the type(s) of microvessel(s) that would give rise to migrating and/or proliferating cells. The isolated cerebral microvessels were heterogeneous in diameter, size of individual vascular isolate, and proliferative potential. The isolated microvessels ranged in diameter from 4 micron to 25 micron and in size from a single microvascular segment to a large multibranched plexus with mural cells. The initial viability, determined by erythrosin B exclusion, was approximately 50% on a per cell basis. All microvessel classes had proliferative potential although the rate and extent of proliferation were both microvessel class- and density-dependent. The smaller microvessels gave rise to endothelial cells, whereas the large microvessels gave rise to endothelial and smooth-muscle cells. The viability and progress of a microvessel toward derived cell proliferation seemed to be directly proportional to the number of mural cells present.

Animals↗

PubMed1992

Microvessel quantitation and prognosis in invasive breast carcinoma.

The prognostic significance of microvessel quantitation in invasive breast carcinoma was analyzed in a study group that comprised 88 patients with axillary node-negative carcinoma and 32 patients with axillary node-positive carcinoma who had a minimum follow-up period of 9 years. Microvessels were identified by immunohistochemistry using antibodies to endothelial markers, including factor VIII-related antigen and blood group isoantigens (ABH). Factor VIII-related antigen staining provided more consistent results for microvessel quantitation than did staining for ABH isoantigens. The three most vascular areas within a tumor were selected, and the microvessels within a x200 microscopic field of each area were counted by two investigators simultaneously. Node-positive carcinomas demonstrated significantly higher microvessel counts than did node-negative carcinomas (mean +/- SD, 99 +/- 42 and 73 +/- 22, respectively; P less than .001). In node-negative carcinomas, tumors from patients who experienced distant recurrence had higher microvessel counts than did tumors from patients who were disease-free (84 +/- 19 and 70 +/- 22; P = .01). Similarly, in patients with node-positive carcinoma, microvessel counts were considerably higher in tumors from patients who experienced distant recurrence than in patients who did not, although the difference did not reach statistical significance (113 +/- 44 and 93 +/- 34, respectively). Among patients with node-negative carcinoma, those with a microvessel count of less than 84 had a recurrence rate of 20% compared with 57% in patients with counts greater than 84 (P = .003). Microvessel counts were independent of histologic parameters, ploidy status, and S-phase fraction but correlated with peritumoral vascular invasion. Both microvessel counts and vascular invasion were independent prognostic parameters by multivariate analysis. High vessel counts may represent increased tumor angiogenesis and are correlated with tumor aggressiveness. Microvessel quantitation may be an additional prognostic factor that, when used in conjunction with more established parameters, can help in appropriate patient management.

Breast Neoplasms↗

PubMed2002

Tumor necrosis factor-alpha-induced leukocyte adhesion and microvessel permeability.

The objective of this study was to investigate whether leukocyte adhesion and/or emigration are critical steps in increased microvessel permeability during acute inflammation. To conduct this study, we combined autologous blood perfusion with a single microvessel perfusion technique, which allows microvessel permeability to be measured precisely after the endothelium has interacted with blood-borne stimuli. Experiments were carried out in intact venular microvessels in rat mesenteries. Firm attachment of leukocytes to endothelial cells was induced by intravenous injection of TNF-alpha (3.5 microg/kg) and resuming autoperfusion in a precannulated microvessel. Leukocyte emigration was facilitated by superfusion of formyl-Met-Leu-Phe-OH. Microvessel permeability was measured as hydraulic conductivity (L(p)) or the solute permeability coefficient to tetramethylrhodamine isothiocyanate-labeled alpha-lactalbumin before and after leukocyte adhesion and emigration in individually perfused microvessels. We found that perfusion of a microvessel with TNF-alpha did not affect basal microvessel permeability, but intravenous injection of TNF-alpha caused significant leukocyte adhesion. However, the significant leukocyte adhesion and emigration did not cause corresponding increases in either L(p) or solute permeability. Thus our results suggest that leukocyte adhesion and emigration do not necessarily increase microvessel permeability and the mechanisms that regulate the adhesion process act independently from mechanisms that regulate permeability. In addition, silver staining of endothelial boundaries demonstrated that leukocytes preferentially adhere at the junctions of endothelial cells. The appearance of the silver lines indicates that the TNF-alpha-induced firm adhesion of leukocyte to microvessel walls did not involve apparent changes in the junctional structure of endothelial cells, which is consistent with the results of permeability measurements.

Animals↗

PubMed1990

Binding of parathyroid hormone and parathyroid hormone-related protein to vascular smooth muscle of rabbit renal microvessels.

The humoral hypercalcemia of malignancy factor (also called PTH-related protein or PTHrp) has been shown to produce effects similar to PTH in the kidney, bone, and cardiovascular system. Binding of PTHrp and PTH has been characterized in renal and osseous tissues, but not in vascular tissue. We have attempted to characterize the interaction of both human PTHrp and rat PTH to renal microvessels as a model of vascular smooth muscle and in a renal tubule preparation from the same rabbit kidneys. Previous studies have shown the microvessel and tubule preparations to be distinct based upon morphological examination, differential enzyme markers, calcitonin and vasopressin-sensitive adenylate cyclase distribution, and different characteristics of guanine nucleotide and of oxidized PTH activation of the adenylate cyclases associated with the preparations. Human PTHrp and rat PTH were iodinated by standard techniques and purified by HPLC. Both ligands bound to microvessels and tubules in a saturable, specific manner, Maximal specific binding of either ligand was 65-75% in microvessels and 80-90% in renal tubules. The time courses of binding of both ligands were identical with steady state achieved within 20 min in the smooth muscle of microvessels and 15 min in the tubules at 22 C. In equilibrium competition binding experiments, bound 125I-PTHrp was displaced by both PTHrp and PTH in microvessels and tubules. Rat PTH displayed slightly higher affinity in microvessels and tubules than PTHrp. Identical results were obtained with 125I-PTH as ligand. Specificity of binding of PTHrp and PTH to both microvessels and tubules was excellent, with competition observed between the radioactive ligand and bovine and rat PTH, PTHrp, and the antagonists, [Nle8,18, Tyr34]bovine PTH and [Nle8,18, Tyr34]bovine PTH but not with several other peptides of unrelated structure. The only major difference in binding between microvessels and tubules was a smaller number of binding sites in microvessels compared to tubules. These results indicate that vascular tissue contains receptor sites for PTH and PTHrp as identified by radioligand binding techniques. These receptors are similar in characteristics to the receptors of renal tubular tissue. Both PTH and PTHrp appear to interact with the receptors of rabbit kidney microvessels and tubules.

Animals↗

PubMed2006

Increased angiogenic response but deficient arteriolization and abnormal microvessel ultrastructure in critical leg ischaemia.

BACKGROUND: Ischaemia is known to induce angiogenesis, but the effects of critical leg ischaemia (CLI) on angiogenesis remain unclear. The aim of this study was to examine the physiological angiogenic response in CLI by investigating the extent of neovascularization, characterizing microvessel subtypes and determining the microvessel ultrastructure. METHODS: Gastrocnemius muscles were biopsied from 12 patients with CLI and 12 without leg ischaemia. Microvessels were evaluated immunohistochemically using three endothelial markers (anti-CD31, anti-CD34 and PAL-E) and anti-alpha smooth muscle actin (SMA) as a mural cell marker to label arterioles. Ki67 was used to demonstrate active cell proliferation. Further microvessel ultrastructural characteristics were determined by transmission electron microscopy. RESULTS: The CLI group had significantly higher microvessel density and microvessel : muscle fibre ratio for all endothelial subtypes examined (P < 0.001). PAL-E staining demonstrated the highest increase: 4.7 times higher in CLI muscle. There was no significant difference in alphaSMA-positive microvessel density (P = 0.118) or microvessel: muscle fibre ratio (P = 0.214). Ki67 staining showed no active cell proliferation. Transmission electron microscopy showed CLI microvessels had abnormal morphology, mainly a thick basement membrane. CONCLUSION: A physiological angiogenic response was found in CLI, but the microvessels had an abnormal ultrastructure. A lack of active cell proliferation suggests that the angiogenic response may have been exhausted.

Aged↗

PubMed1993

Vasoactivity of isolated coronary arterial microvessels: influence of albumin.

Previous investigators have reported the development of spontaneous tone, a spontaneous decrease in diameter in response to application of intraluminal pressure, in isolated microvessels bathed in physiological salt solution (PSS) containing albumin. In contrast, myogenic activity and spontaneous tone are rare in microvessels bathed in albumin-free PSS. The purpose of this study was to determine whether albumin and/or the development of spontaneous tone altered coronary microvessel responsiveness to vasoactive agents. Microvessels (70-150 microns) were isolated from the hearts of domestic pigs and studied in vitro using video dimension analysis. Control microvessels were bathed in albumin-free PSS while albumin-treated vessels were bathed in PSS containing 10 mg/ml albumin. Vasoconstrictor responses were determined for acetylcholine (3 x 10(-10) to 1 x 10(-5) M) and KCl (20-120 mM). Concentration-response curves were generated for an endothelium-dependent vasodilator, bradykinin (1 x 10(-12) to 1 x 10(-7) M), and a direct smooth muscle dilator, sodium nitroprusside (1 x 10(-10) to 1 x 10(-4) M). Seventy-seven percent of the albumin-treated microvessels developed spontaneous tone, whereas only 20% of the control microvessels developed tone. KCl and acetylcholine induced contraction in both control and albumin-treated microvessels. Maximal response to acetylcholine (percentage constriction) was significantly greater in albumin-treated microvessels (79.93 +/- 2.53 and 68.86 +/- 3.20 in control and albumin-treated groups, respectively). Responses to bradykinin and sodium nitroprusside were not different between albumin-treated and control groups. The results indicate that microvessels develop spontaneous tone more frequently when bathed in PSS containing albumin.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗

PubMed1995

Angiogenesis in bladder cancer: relationship between microvessel density and tumor prognosis.

BACKGROUND: Tumor stage, histologic grade, and regional lymph node status are currently used to obtain prognostic information about bladder cancers. However, additional prognostic indicators are needed to aid clinicians in selecting patients who would benefit most from specific therapies. A majority of studies assessing the prognostic value of measuring tumor angiogenesis (i.e., measurement of tumor microvessel densities) have found a positive association between increasing microvessel densities and worsening prognosis. PURPOSE: We explored the relationship between established prognostic indicators and the extent of tumor-associated angiogenesis in patients with invasive transitional cell carcinoma (TCC) of the bladder, and we determined whether tumor microvessel density measurement could be used independently to predict bladder tumor behavior. METHODS: Tumor tissue was obtained from 164 patients with invasive primary TCC of the bladder. The extent of tumor-associated angiogenesis in this tissue was evaluated by immunohistochemical methods using HPCA-1, a mouse monoclonal antibody directed against the endothelial cell antigen, CD34. The number of microvessels in a 200x microscopic high-power field (hpf) containing the area of greatest neovascularization within or immediately adjacent to each tumor was determined. The patient population was then divided into three equivalently sized groups, with tumors containing low (< or = 64), intermediate (65-99), or high (> or = 100) numbers of microvessels per hpf. Kaplan-Meier product limit estimates of overall survival and the complement of cumulative incidence curves for recurrence-free survival were plotted. When analyzing survival or recurrence, the logrank test was used to compare groups of patients with and without stratification according to tumor stage. Analysis of variance was used to test for an association between microvessel density and established prognostic variables. Reported P values are from two-sided tests. RESULTS: Microvessel density was significantly associated with disease-free (P < .0001) and overall (P = .0007) survival. The estimated probabilities of recurrence at 5 years were 19% (95% confidence interval [CI] = 8-29), 56% (95% CI = 43-69), and 68% (95% CI = 55-81) for patients with lowest, intermediate, and highest microvessel counts, respectively. Overall survival at 5 years was estimated to be 68% (95% CI = 56-81), 44% (95% CI = 30-57), and 34% (95% CI = 21-47) for the same three patient groups. Microvessel density was associated with disease progression in patients with organ-confined tumors, tumors extending through the bladder wall, and tumors that had spread to regional lymph nodes. Tumor angiogenesis was found to be an independent prognostic indicator when evaluated in the presence of histologic grade, pathologic stage, and regional lymph node status. CONCLUSION: Tumor angiogenesis, as determined by microvessel density measurement, is an independent prognostic indicator for patients with invasive TCC of the bladder.

Adult↗

PubMed2005

Comparison of microvessel densities in rat prostate tissues treated with finasteride, bicalutamide and surgical castration: a preliminary study.

BACKGROUND: A group of anti-androgens with different mechanisms of action and adverse effects have been investigated in patients with gross hematuria related to benign prostate hyperplasia; however, there is not yet any consensus about the standard management of these patients. The present study aims to identify if any one type of the hormonal intervention is superior in terms of the suppression of microvessel formation in the prostate. MATERIALS AND METHODS: A total of 28 mature, healthy male Sprague-Dawley rats (300 +/- 50 g) were used in this study. The rats were randomly assigned to one of four groups (n = 7 per group). The effects of three different hormonal therapies on angiogenesis and microvascularity in rat ventral prostate were compared. Groups 1 and 2 were treated for 28 days with finasteride and bicalutamide, respectively, and rats from Group 3 underwent surgical castration. Following treatment, all rats included in the study underwent dissection of the ventral prostate and immunohistochemical analysis of microvessel density by factor VIII-related antigen. RESULTS: The mean number of microvessels in the finasteride and bicalutamide groups was 24.5 (+/-8.44 SE) and 27 (+/-9.89 SE) respectively. In contrast, the castration and control groups had microvessel numbers of 12.9 (+/-5.35 SE) and 40.3 (+/-5.03 SE) respectively. Differences were statistically significant between all three treatment groups and the controls (P < 0.005); the number of microvessels in rat prostate tissues of the control group was significantly higher than the treatment groups. Mean microvessel densities in the bicalutamide and finasteride groups were significantly higher than microvessel densities in the castration group (P < 0.005). There was no statistically significant difference between mean microvessel number in rat prostate tissue treated with finasteride or bicalutamide (P > 0.05). CONCLUSIONS: Even though finasteride was not as effective as castration in reducing microvessel number, its effect was equal to that of bicalutamide in terms of suppressing the angiogenesis in prostatic tissue. Based on the findings of the present study, finasteride might offer a viable option in the management of macroscopic hematuria by inhibition of microvessel formation within the prostatic tissue. Further clinical studies are warranted.

Androgen Antagonists↗

PubMed1999

Fully automated microvessel counting and hot spot selection by image processing of whole tumour sections in invasive breast cancer.

BACKGROUND: Manual counting of microvessels is subjective and may lead to unacceptable interobserver variability, which may explain conflicting results. AIMS: To develop and test an automated method for microvessel counting and objective selection of the hot spot, based on image processing of whole sections, and to compare this with manual selection of a hot spot and counting of microvessels. METHODS: Microvessels were stained by CD31 immunohistochemistry in 10 cases of invasive breast cancer. The number of microvessels was counted manually in a subjectively selected hot spot, and also in the same complete tumour sections by interactive and automated image processing methods. An algorithm identified the hot spots from microvessel maps of the whole tumour section. RESULTS: No significant difference in manual microvessel counts was found between two observers within the same hot spot, and counts were significantly correlated. However, when the hot spot was reselected, significantly different results were found between repeated counts by the same observer. Counting all microvessels manually within the entire tumour section resulted in significantly different hot spots than manual counts in selected hot spots by the same observer. Within the entire tumour section no significant differences were found between the hot spots of the manual and automated methods using an automated microscope. The hot spot was found using an eight connective path search algorithm, was located at or near the border of the tumour, and (depending on the size of the hot spot) did not always contain the field with the largest number of microvessels. CONCLUSIONS: The automated counting of microvessels is preferable to the manual method because of the reduction in measurement time when the complete tumour is scanned, the greater accuracy and objectivity of hot spot selection, and the possibility of visual inspection and relocation of each measurement field afterwards.

Breast Neoplasms↗

PubMed1996

Erythrocyte flow and elasticity of microvessels evaluated by marginal cell-free layer and flow resistance.

Flow dynamics of human erythrocytes was compared in elastic (E) and hardened (H) microvessels with inner diameters of 10-40 microns. The thickness of the marginal cell-free layer and the overall flow resistance were measured with a vascular bed isolated from rabbit mesentery (E vascular bed) as well as with a 4% paraformaldehyde-fixed bed (H vascular bed). 1) In both E and H microvessels, the thickness of the cell-free layer increased with increasing inner diameter of the microvessels and with decreasing hematocrit accompanied by an overall decrease in the flow resistance. The hematocrit-dependent change of the cell-free layer thickness was greater in the E microvessels than in the H microvessels. The flow resistance was always greater in the H vascular beds than in the E vascular beds. 2) With decreasing erythrocyte deformability induced by treatment with 2 mM diazenedicar-boxylic acid bis(N,N-dimethylamide), the thickness of the cell-free layer decreased at a low hematocrit in the E microvessels and at a high hematocrit in the H microvessels, although the flow resistance was increased in both vascular beds. 3) Dextran of 70,400 average molecular weight accelerated the formation of the cell-free layer by inducing erythrocyte aggregation. A drastic increase in the cell-free layer thickness at 2-4 g/dl of dextran in the E microvessels and at 1-2 g/dl of dextran in the H microvessels was accompanied by a significantly lower increase in the flow resistance. This study concludes that the elasticity of microvessels may play an important role for reducing the overall flow resistance of a vascular bed, which is modulated by the marginal cell-free layer, itself a function of the rheological properties of the erythrocytes.

Animals↗

PubMed2004

Prevalence of fetal-type smooth muscle cells in the media of microvessels from hypertensive patients.

Significant structural and functional changes in smooth muscle cells (SMCs) of microvessels (diameter 30 to 300 microm) occur in hypertension. However, in microvessels of hypertensive patients, the differentiation pattern of SMCs underlying such changes remains undefined. To analyze the differentiation pattern of SMCs (adult, postnatal, or fetal), 49 muscle biopsies (rectus abdominis) were analyzed: 16 from children (aged 11 months to 11 years), 15 from normotensive adults (aged 55 to 74 years), 18 from hypertensive adults (aged 55 to 74 years). Transverse cryosections of specimens were studied by immunocytochemistry using monoclonal antibodies SM-E7 and NM-F6, which recognize smooth muscle myosin heavy chain (MyHC) and A(pla1)-like nonmuscle MyHC, respectively. The total number of microvessels was assessed via SM-E7 staining. The number of NM-F6 positive (fetal-type SMC) or negative (adult-type SMC) microvessels was assessed. The number of microvessels per area unit was considerably lower (P<0.0005) in normotensive adults (0.22+/-0.17) than in children (0.98+/-0.61). Even more significant reduction was found in hypertensive adults compared with control adults (P=0.013) and children (P<0.0005). The qualitative immunocytochemistry analysis by NM-F6 revealed 2 differentiation patterns of the media layer of microvessels: positive or negative. In hypertensive subjects, the percentage of microvessels positive to NM-F6 was 49.8+/-35.6%, close to that found in children (50.6+/-12.6%), whereas in normotensive subjects it was significantly lower (24.4+/-21.1%). The following conclusions were drawn. (1) The medial layer of microvessels is heterogeneous in terms of SMC differentiation. (2) In hypertension, a prevalence of fetal-type SMCs takes place in microvessels, resembling that of children. Compared with children, a rarefaction of microvessels is present in normotensive adults that is even more remarkable in hypertensive adults.

Aged↗

PubMed1994

Correlation of intratumoral endothelial cell proliferation with microvessel density (tumor angiogenesis) and tumor cell proliferation in breast carcinoma.

Tumor angiogenesis is essential for tumor growth and metastasis, and intratumoral microvessel density correlates with prognosis in breast carcinoma. Yet, how intratumoral microvessel density correlates with tumor cell and intratumoral endothelial cell proliferation remains incompletely understood. To this end, we stained 57 formalin-fixed, paraffin-embedded breast carcinomas with antibody MIB1 to determine tumor cell Ki67 labeling index and with anti-CD34 to observe microvessels. We correlated the tumor cell Ki67 labeling index and mitotic figure index with intratumoral microvessel density. Using a double labeling technique combining antibody MIB1 and anti-CD34, we measured intratumoral endothelial cell proliferation in 20 of these cases and correlated these findings with tumor cell Ki67 labeling index, mitotic figure index, and intratumoral microvessel density. The intratumoral Ki67-labeling index was 45-fold greater (P < 0.000001) than that of microvessels in adjacent benign breast. Yet, endothelial cell Ki67 labeling index did not correlate with intratumoral microvessel density, tumor cell Ki67 labeling index, or mitotic figure index nor did intratumoral microvessel density correlate with tumor cell Ki67 labeling index or mitotic figure index. These findings suggest that, although endothelial cells are actively proliferating within the tumor, intratumoral microvessel density and intratumoral endothelial cell proliferation are independent of each other and of tumor cell proliferation. Thus, intratumoral microvessel density, endothelial cell proliferation, and tumor cell proliferation may be regulated by separate mechanisms.

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