Vascular distribution of nitric oxide synthase and vasodilation in the Australian lungfish, Neoceratodus forsteri

The presence of nitric oxide synthase (NOS) and role of nitric oxide (NO) in vascular regulation was investigated in the Australian lungfish, Neoceratodus forsteri. No evidence was found for NOS in the endothelium of large and small blood vessels following processing for NADPH-diaphorase histochemistry. However, both NADPH-diaphorase histochemistry and neural NOS immunohistochemistry demonstrated a sparse network of nitrergic nerves in the dorsal aorta, hepatic artery, and branchial arteries, but there were no nitrergic nerves in small blood vessels in tissues. In contrast, nitrergic nerves were found in non-vascular tissues of the lung, gut and kidney. Dual-wire myography was used to determine if NO signalling occurred in the branchial artery of N. forsteri. Both SNP and SIN-1 had no effect on the pre-constricted branchial artery, but the particulate guanylyl cyclase (GC) activator, C-type natriuretic peptide, always caused vasodilation. Nicotine mediated a dilation that was not inhibited by the soluble GC inhibitor, ODQ, or the NOS inhibitor, L-NNA, but was blocked by the cyclooxygenase inhibitor, indomethacin. These data suggest that NO control of the branchial artery is lacking, but that prostaglandins could be endothelial relaxing factors in the vasculature of lungfish.

Requirements for ICAM-1 immunogene therapy of lymphoma.

Intercellular cell adhesion molecule-1 (ICAM-1) is a cell-surface glycoprotein capable of eliciting bidirectional signals that activate signalling pathways in leukocytes, endothelial, and smooth muscle cells. Gene transfer of xenogeneic ICAM-1 into EL-4 lymphomas causes complete tumor rejection; however, it is unknown whether the mechanism responsible involves the "foreignness" of the ICAM-1 transgene, bidirectional signalling events, ICAM-1-receptor interaction, or a combination of the latter. To begin to address this question, we constructed four different therapeutic expression vectors encoding full-length ICAM-1, and forms in which the N-terminal ligand-binding domains and cytoplasmic tail had been deleted. Mouse EL-4 tumors (0.5 cm in diameter), which actively suppress the immune response, were significantly inhibited in their growth following injection of expression plasmids encoding either full-length xenogenic (human) ICAM-1, or a functional cytoplasmic domain-deficient form that retains ligand-binding activity. Efficacy of ICAM-1-mediated antitumor immunity was significantly augmented by administration of the antivascular drug 5,6-dimethylxanthenone-4-acetic acid (DMXAA), which suppressed blood supply to the tumor, leading to enhanced leukocyte infiltration, and complete tumor eradication in a gene dosage and CD8(+) T cell and NK cell-dependent fashion. Generation of potent cytotoxic T cell (CTL)-mediated antitumor immunity was reflected by ICAM-1-facilitated apoptosis of tumor cells in situ. In contrast, nonfunctional ICAM-1 lacking the N-terminal ligand-binding Ig domain failed to generate antitumor immunity, even in the presence of DMXAA. These studies demonstrate that ICAM-1-stimulated antitumor immunity can overcome tumor-mediated immunosuppression, particularly when employed in combination with an attack on the tumor vasculature. The ligand-binding domain of ICAM-1 is essential for generating antitumor immunity, whereas the cytoplasmic domain and bidirectional activation of tumor signalling pathways are not essential.

Multicellular spheroids in ovarian cancer metastases: Biology and pathology

Epithelial ovarian cancer (EOC) has a relatively high mortality rate (~55%). One of the presiding causes is that the current chemotherapeutic regimes are unable to achieve sustained remission, despite frequently producing a positive response at first treatment. One of the reasons that EOC is difficult to treat is that the mechanism of dissemination is unusual. EOC dissemination characteristically involves local invasion of pelvic and abdominal organs. Unlike many epithelial cancers, initial dissemination rarely requires the vasculature, although the vasculature is often implicated in the advanced stages of disease. Recently, it has become apparent that aggregates of malignant cells (spheroids) contained within malignant ascites represent a significant impediment to efficacious treatment of late stage EOC. In vivo, spheroids are present in the malignant ascites of EOC patients, while in vitro cultured spheroids are capable of tumorgenesis in vivo and display a reduced response to chemotherapeutic drugs when compared to monolayers. A major problem associated with the current generation of chemotherapy agents is that they do not address the anchorage and vascular-independent growth conditions associated with a 3-dimensional structure that has formed and/or grown in suspension. Thus, spheroid formation may represent a key component of platinum/taxanesensitive recurrence. If this is correct, a better understanding of spheroid biology may contribute to the identification of new treatment opportunities for the sustained treatment of metastatic EOC. This review article outlines the key biological features of spheroids, specifically discussing their role in EOC dissemination and chemo-response as well as providing insights into spheroid functionality.

Recent advances in nanoneurology for drug delivery to the brain

The drug development for neurodegenerative disorders are the major challenge to the science in 21st century. Many FDA approved drugs currently available in the market have limitations in crossing the blood brain barrier (BBB) owing to its complicated vasculature posed by the presence of specialized cells. Nanotechnology is an emerging interdisciplinary area, which have many applications including drug delivery. Nanocarrier drug delivery involves targeting drugs enclosed in a particular polymer and/or amphiphilic lipids. Controlled release, nanoplatform availability for combinatorial therapy and tissue specific targeting by using advanced technologies such as molecular Trojan horse (MTH) technology are the promises of nanotechnology. Different problems are associated with drug delivery
across the BBB. Some are mostly related to the structure of brain microvasculature system while the others are related to the nanomaterial
structure. Different strategies, such as using polymeric/solid lipid nanoparticles and surface modification of nanomaterial with surfactants
like polysorbates have been conducted to solve these limitations. Also, nanodrug formulations with double coatings have been designed for oral delivery of drugs to overcome reticulo-endothelial system and to improve their BBB permeability. It seems that the best choice of strategy and material could be achieved with regard to the physical and chemical structure of the drugs. The present review discusses the potential applications of nanotechnology for drug delivery across the BBB.

Soy isoflavones improve systemic arterial compliance but not plasma lipids in menopausal and perimenopausal women

The possibility that the heightened cardiovascular risk associated with the menopause, which is said to be ameliorated by soybeans, can be reduced with soy isoflavones was tested in 21 women. Although several were perimenopausal, all have been included. A placebo-controlled crossover trial tested the effects of 80-mg daily isoflavones (45 mg genistein) over 5- to 10-week periods. Systemic arterial compliance (arterial elasticity), which declined with age in this group, improved 26% (P < .001) compared with placebo. Arterial pressure and plasma lipids were unaffected. The vasodilatory capacity of the microcirculation was measured in nine women; high acetylcholine-mediated dilation in the forearm vasculature was similar with active and placebo treatments. LDL oxidizability measured in vitro was unchanged. Thus, one important measure of arterial health, systemic arterial compliance, was significantly improved in perimenopausal and menopausal women taking soy isoflavones to about the same extent as is achieved with conventional hormone replacement therapy.

Mechanisms involved in the renal responses to intravenous and renal artery infusions of noradrenaline in conscious dogs

1. The renal haemodynamic and glomerular filtration rate (G.F.R.) responses to intravenous and intrarenal infusions of noradrenaline were studied in conscious dogs, either with or without prior blockade of angiotensin II formation with teprotide.

2. Infusion noradrenaline by either route resulted in dose-related rises in plasma renin activity.

3. Pretreatment with teprotide reduced the rise in mean arterial pressure and abolished the rise in G.F.R. seen during intravenous infusions of noradrenaline (0.1, 0.2 and 0.4 microgram/kg . min). Noradrenaline also reduced filtration fraction more after teprotide pretreatment.

4. Renal blood flow rose and renal vascular resistance fell in response to I.V. noradrenaline infusions. This renal vasodilatation was unaffected by pretreatment of the dogs with teprotide, indomethacin or DL-propranolol. However after pentolinium pretreatment, I.V. noradrenaline infusion caused a dose-related renal vasoconstriction.

5. Infusion of noradrenaline into the renal artery (0.02, 0.05 and 0.1 microgram/kg . min) resulted in rises in mean arterial pressure and G.F.R. which were abolished by teprotide pretreatment. Filtration fraction rose when noradrenaline was administered alone but fell when it was infused after teprotide treatment.

6. Thus angiotensin II formed as the result of increased renin release acted to maintain G.F.R. and filtration fraction during noradrenaline infusion. In addition, I.V. noradrenaline infusions in conscious dogs caused reflex vasodilatation of the renal vasculature.

Role of angiotensin II in the hypertension induced by renal artery stenosis

Identical degrees of renal artery stenosis were induced in 5 dogs on two separate occasions; once during continuous inhibition of angiotensin I converting enzyme with enalapril, and once with the dogs untreated. Arterial pressure rose about 25 mm Hg during 3 days of stenosis in untreated dogs, due to increased total peripheral resistance. When the dogs were treated with enalapril, blood pressure had risen 14.5 ± 3.4 mm Hg 24 hours after stenosis due to a 35% increase in cardiac output while total peripheral resistance fell by 16%. By the third day, blood pressure had returned to pre-stenosis levels, cardiac output was close to normal and total peripheral resistance had increased. The stenosis on the renal artery increased the resistance to blood flow of the kidneys in both untreated and enalapril treated dogs. This increase in kidney resistance in the untreated dogs accounted for about 30% of the change in total peripheral resistance. In the enalapril treated dogs, the increased kidney resistance helped offset the vasodilatation in the rest of the vasculature. These results suggest that angiotensin II mediated vasoconstriction of nonrenal vascular beds was responsible for about ⅔ of the hypertension following renal artery stenosis, and the resistance of the stenosis responsible for about ⅓.

Investigation of GMP signalling systems in lower vertebrates

This research examined aspects of the cyclic GMP signalling system in fish and amphibians. It contributed new knowledge to our understanding of the role of the system in the development of zebrafish, a model fish species, and in control of the vasculature by the regulatory molecule, nitric oxide.

Use of a photographic manipulation tool to assess corneal vascular response

Purpose. Corneal vasculature change in contact lens wearers has been linked to the level of hypoxia within the cornea. To assess the impact a treatment has on limbal vessels, a sensitive method of measurement and quantification is required.

Methods. A group of 21 highly myopic, hydrogel wearers, with preexisting signs of corneal hypoxia, were enrolled into a study where they wore sifilcon A silicone hydrogel lenses (Dk/t = 117), on a daily wear basis for 9 months. At all scheduled visits, photographs were taken of the superior, inferior, temporal, and nasal limbal regions which were then imported into Adobe Photoshop. A red-free filter was applied to enhance the contrast of the blood columns. In each quadrant, the length of the longest visible blood column was measured and the blood columns that penetrated >0.5 mm into the cornea were counted. A control group of 11 non-lens wearers was recruited. Their photographs were taken at the beginning of the study and 9 months later. An independent, masked observer assessed the photographs.

Results. There was a significant decrease in the maximum penetration of the blood column in all quadrants (p < 0.001) from baseline to the 9-month visit (e.g., superior: baseline 0.84 ± 0.39 mm; 9 months 0.63 ± 0.20 mm). There was also significant reduction in the number of visible blood columns longer than 0.5 mm in each quadrant (p < 0.001) from baseline to 9 months in all quadrants (e.g., superior: baseline 14.0 ± 8.2; 9 months 6.5 ± 6.0). The control group showed no change over time for the maximum blood column length (p = 0.638) or the number of columns >0.5 mm (p = 0.341).

Conclusions. A group of highly myopic subjects exhibited reduction in the maximum length and number of blood columns in the cornea when refit with a highly permeable silicone hydrogel material. The use of photography, along with Adobe Photoshop software, provides a reliable way of measuring corneal vascular responses over time.

Oxygen-dependence of metabolic rate in the muscles of craniates

We present evidence that oxygen consumption (V_O2 ) is oxygen partial pressure (P_O2) dependent in striated muscles and P_O2 -independent in the vasculature in representatives of three craniate taxa: two teleost fish, a hagfish and a rat. Blood vessel V_O2 displayed varying degrees of independence in a P_O2 range of 15–95 mmHg, while V_O2 by striated muscle tissue slices from all species related linearly to P_O2 between 0 and 125 mmHg, despite V_O2 rates varying greatly between species and muscle type. In salmon red muscle, lactate concentrations fell in slices incubated at a P_O2 of either 30 or 100 mmHg, suggesting aerobic rather than anaerobic metabolism. Consistent with this finding, potential energy, a proxy of ATP turnover, was P_O2 -dependent. Our data suggest that the reduction in V_O2 with falling P_O2 results in a decrease in ATP demand, suggesting that the hypoxic signal is sensed and cellular changes effected. Viability and diffusion limitation of the preparations were investigated using salmon cardiac and skeletal muscles. Following the initial P_O2 depletion, reoxygenation of the Ringer bathing salmon cardiac muscle resulted in V_O2^s that was unchanged from the first run. V_O2 increased in all muscles uncoupled with p-trifluoromethoxylphenyl-hydrazone (FCCP) and 2,4-dinitrophenol (DNP). Mitochondrial succinate dehydrogenase activity, quantified by reduction of 3-(4,5-dimethylthiazol)-2,5-diphenyl-2H-tetrazolium bromide (MTT) to formazan, was constant over the course of the experiment. These three findings indicate that the tissues remained viable over time and ruled out diffusion-limitation as a constraint on V_O2.

Current protein-based anti-angiogenic therapeutics

 Angiogenesis is a complex multistep process of formation of new blood vessels. Interactions between several cellular factors including growth factors, cytokines and haematopoietic factors lead to activation of various cellular pathways, finally resulting in extracellular matrix (ECM) degradation, endothelial cell proliferation, survival and migration. Normally, angiogenesis is an essential requirement for vascular development in growing embryos as well as in adult tissues, where this process depends on the intricate balance between the activities of the pro- and anti-angiogenic factors. Abnormal angiogenesis results in aberrant vasculature leading to various pathological conditions. The most important factor implicated in angiogenic processes in vascular endothelial growth factor (VEGF) and its family of ligands and receptors. Several anti-angiogenic drugs have been developed and many more are currently in different phases of clinical trials, which target various angiogenesis-inducing agents, including VEGF, VEGF receptors, angiopoietins and ECM components such as integrins. Anti-angiogenic therapy can be divided into gene-based therapy and protein-based therapy. Gene-based therapies include use of antisense oligonucleotides, siRNA, aptamers, catalytic oligonucleotides including ribozymes and DNAzymes and transcription decoys. Protein-based therapeutics includes monoclonal antibodies, peptidomimetics, fusion proteins and decoy receptors. The later class of therapeutics has several advantages over gene-based and small molecule drugs, including specificity and complexity in functions, better tolerability, less interference with normal biological processes and lesser adverse effects due to decreased immune response by virtue of being mostly body's natural proteins. This review provides a comprehensive overview of angiogenesis and on the current protein-based anti-angiogenic therapeutics under research and in the clinic.

Vascular contribution to metastasis

It has been 40 years since Folkman's seminal paper [Cancer Res 1974. 34:2109-13], proposing the presence of a tumour associated angiogenic factor, which could be targeted as an anticancer therapy. There are currently a handful of drugs in trial or use that have been marketed as targeting angiogenesis. Unfortunately, the most widely used of these, bevacizumab (Avastin™, Roche), has met with limited success clinically. For this reason and based on a calculation of cost benefit, bevacizumab is now only publically subsidised for use in a limited range of solid tumours. That the contribution of vasculature to malignancy remains poorly understood is increasingly clear. At the same time, the traditional view that vascularisation is a passive participant in the process of malignancy, and that endothelium merely provides a conduit by which tumour cells spread, is being replaced with an understanding that vasculature is a key player in the process of metastasis. Furthermore, the identification of non-traditional sources of vasculature has complicated our understanding of the tumour endothelium as a unique population that can be simply targeted as an anticancer therapy. The following review seeks to provide an up-to-date view of vascular contribution to metastasis and implications for new vasculature-targeted anticancer treatments.

Nervous control of circulation--the role of gasotransmitters, NO, CO, and H2S.

The origins and actions of gaseous signaling molecules, nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H(2)S) in the mammalian cardiovascular system have received considerable attention and it is evident that these three "gasotransmitters" perform a variety of homeostatic functions. The origins, actions and disposition of these gasotransmitters in the piscine vasculature are far from resolved. In most fish examined to date, NO or NO donors are generally in vitro and in vivo vasodilators acting via soluble guanylyl cyclase, although there is evidence for NO-mediated vasoconstriction. Injection of sodium nitroprusside into trout causes hypotension that is attributed to a reduction in systemic resistance. Unlike mammals, NO does not appear to have an endothelial origin in fish blood vessels as an endothelial NO synthase has not identified. However, neural NO synthase is prevalent in perivascular nerves and is the most likely source of NO for cardiovascular control in fish. CO is a vasodilator in lamprey and trout vessels, and it, like NO, appears to exert its action, at least in part, via guanylyl cyclase and potassium channel activation. Inhibition of CO production increases resting tone in trout vessels suggestive of tonic CO activity, but little else is known about the origin or control of CO in the fish vasculature. H(2)S is synthesized by fish vessels and its constrictory, dilatory, or even multi-phasic actions, are both species- and vessel-specific. A small component of H(2)S-mediated basal activity may be endothelial in origin, but to a large extent H(2)S affects vascular smooth muscle directly and the mechanisms are unclear. H(2)S injected into the dorsal aorta of unanesthetized trout often produces oscillations in arterial blood pressure suggestive of H(2)S activity in the central nervous system as well as peripheral vasculature. Collectively, these studies hint at significant involvement of the gasotransmitters in piscine cardiovascular function and hopefully provide a variety of avenues for future research.

Análise fractal da vasculatura arteriolar e venular da retina em pessoas sem doença ocular

Although it has been suggested that retinal vasculature is a diffusion-limited aggregation (DLA) fractal, no study has been dedicated to standardizing its fractal analysis . The aims of this project was to standardize a method to estimate the fractal dimensions of retinal vasculature and to characterize their normal values; to determine if this estimation is dependent on skeletization and on segmentation and calculation methods; to assess the suitability of the DLA model and to determine the usefulness of log-log graphs in characterizing vasculature fractality . To achieve these aims, the information, mass-radius and box counting dimensions of 20 eyes vasculatures were compared when the vessels were manually or computationally segmented; the fractal dimensions of the vasculatures of 60 eyes of healthy volunteers were compared with those of 40 DLA models and the log-log graphs obtained were compared with those of known fractals and those of non-fractals. The main results were: the fractal dimensions of vascular trees were dependent on segmentation methods and dimension calculation methods, but there was no difference between manual segmentation and scale-space, multithreshold and wavelet computational methods; the means of the information and box dimensions for arteriolar trees were 1.29. against 1.34 and 1.35 for the venular trees; the dimension for the DLA models were higher than that for vessels; the log-log graphs were straight, but with varying local slopes, both for vascular trees and for fractals and non-fractals. This results leads to the following conclusions: the estimation of the fractal dimensions for retinal vasculature is dependent on its skeletization and on the segmentation and calculation methods; log-log graphs are not suitable as a fractality test; the means of the information and box counting dimensions for the normal eyes were 1.47 and 1.43, respectively, and the DLA model with optic disc seeding is not sufficient for retinal vascularization modeling

The role of indomethacin and tezosentan on renal effects induced by Bothrops moojeni Lys49 myotoxin I

Renal changes determined by Lys49 myotoxin I (BmTx I), isolated from Bothrops moojeni are well known. The scope of the present study was to investigate the possible mechanisms involved in the production of these effects by using indomethacin (10 mu g/mL), a non-selective inhibitor of cyclooxygenase, and tezosentan (10 mu g/mL), an endothelin antagonist. By means of the method of mesenteric vascular bed, it has been observed that B. moojeni myotoxin (5 mu g/mL) affects neither basal perfusion pressure nor phenylephrine-preconstricted vessels. This fact suggests that the increase in renal perfusion pressure and in renal vascular resistance did not occur by a direct effect on renal vasculature. Isolated kidneys from Wistar rats, weighing 240-280 g, were perfused with Krebs-Henseleit solution. The infusion of BmTx-I increased perfusion pressure, renal vascular resistance, urinary flow and glomerular filtration rate. Sodium, potassium and chloride tubular transport was reduced after addition of BmTx-I. Indomethacin blocked the effects induced by BmTx-I on perfusion pressure and renal vascular resistance, however, it did not revert the effect on urinary flow and sodium, potassium and chloride tubular transport. The alterations of glomerular filtration rate were inhibited only at 90 min of perfusion. The partial blockade exerted by indomethacin treatment showed that prostaglandins could have been important mediators of BmTx-I renal effects, but the participation of other substances cannot be excluded.The blockage of all renal alterations observed after tezosentan treatment support the hypothesis that endothelin is the major substance involved in the renal pathophysiologic alterations promoted by the Lys49 PLA(2) myotoxin I, isolated from B. moojeni. In conclusion, the rather intense renal effects promoted by B. moojeni myotoxin-I were probably caused by the release of renal endothelin, interfering with the renal parameters studied. (c) 2006 Elsevier Ltd. All rights reserved.