Vascular Circulation Research Articles

Robust Revascularization, Despite Impaired VEGF Production, After Meniscus Allograft Transplantation in Rabbits

Background: Little is known about vascularization restoration and vascular circulation after allogenic graft transplantation, which are both important prerequisites for optimal use of allograft meniscus transplantation. Purpose: To study vascularization restoration through autograft and allograft meniscus models in Oryctolagus cuniculus. Study Design: Controlled laboratory study. Methods: Forty-eight rabbits at mature bone age were randomized to receive either an autograft or allograft after the meniscus of the left knee was completely resected. Vascularization, blood circulation, histological characteristics of the grafted meniscus and surrounding tissues, and vascular endothelial growth factor (VEGF) expression in the meniscus were assessed at 4, 8, and 12 weeks after allograft or autologous transplantation. Results: The grafted meniscus was in good condition and was well connected to the surrounding joint capsule, and no obvious damage of the joint cartilage at the tibial plateau was observed. Even though the revascularization pattern was similar in the 2 groups, the meniscus body showed vessel growth mainly at the adhesion margin for less than one-third of the meniscus transverse diameter, and no significant vascular distribution was found at the free margin. Blood circulation peaked after 8 weeks at the anterior and posterior horns and declined thereafter. This was mimicked by VEGF expression, which showed a progressive decrease with time, even though the vascular endothelial cells gradually increased over time. There were no statistical differences in the various assessments between the allograft and autograft groups. Conclusion: At 12 weeks after meniscus allografting, the vascular circulation had almost recovered and gradual reconstruction of cells and fibers had begun, mimicking similar observations in the autograft group. Clinical Relevance: Our data provide test reference for clinical rehabilitation after meniscus autograft.

혈액순환과 관련하여 nitric oxide 생성과 angiotensin converting enzyme 활성에 미치는 Acai berry 에탄올 추출물의 영향

본 연구의 목적은 혈관계 순환을 촉진시키는 약효제를 발굴하는 것이다. 아사이베리(Acai berry) 에탄올 추출물(ABEE)의 항산화 효과 뿐만 아니라 토끼의 폐에서 유래한 angiotensin converting enzyme (ACE)의 활성 및 대식세포와 혈관내피세포에서 nitric oxide 생성에 대한 효과가 본 연구에서 조사되었다. 먼저 환원력과 지질과산화에 대한 ABEE의 항산화효과가 관찰되었다. 뿐만 아니라, ABEE는 hydroxyl radical에 의하여 유발된 DNA 산화에 대한 보호효과를 보여주었다. 더욱이 ABEE는 0.01%의 농도에서 약 50% 정도의 angiotensin converting enzyme 활성에 대한 억제효과를 발휘하는 것으로 나타났다. 혈관내피세포에서 ABEE는 nitric oxide 의 생성을 증가시켰으나 대식세포에서는 lipopolysaccharide에 의하여 생성된 nitric oxide 생성을 감소시켰다. 게다가 superoxide dismutase (SOD)-2와 -3 발현수준은 ABEE 처리에 의하여 증가되었으나 SOD-1의 발현수준은 일정하였다. 더욱이 nitric oxide synthases-1 (NOS-1)의 발현수준은 ABEE 처리에 의하여 증가되었으나, 유발 효소인 NOS-2의 발현수준은 일정하였다. 또한 SOD의 전사인자인 Nrf-2의 발현수준은 ABEE에 의하여 증가되었다. 그러므로 이러한 결과들은 ABEE가 이상의 작용을 경유하여 혈액순환을 촉진시킬 수 있고, 혈관의 건강을 위한 큰 잠재성을 가지고 있다는 것을 암시하고 있다. The aim of this study is to develop a supplementary therapeutic agent capable of promoting vascular circulation. The effects of Acai berry ethanolic extracts (ABEE) on activity of angiotensin converting enzyme from rabbit lung, production of nitro oxide in both murine macrophage cells and vascular endothelial cells as well as antioxidant effects were investigated in this study. First of all, it was observed the direct effects of ABEE on reducing power and antioxidant effect lipid peroxidation. In addition, ABEE showed a protective effect on DNA oxidation induced by hydroxyl radical. Furthermore, ABEE at 0.01% exerted approximately 50% inhibition on activity of angiotensin converting enzyme. ABEE increased the production of nitric oxide in endothelial cells, but decreased the induction of nitric oxide stimulated by lipopolysaccharide in microphage. The expression levels of superoxide dismutase (SOD)-2 and -3 were enhanced by ABEE treatment, however, the expression level of SOD-1 remained constant. Moreover, the expression level of nitric oxide synthases-1 (NOS-1), a constitutive enzyme, was increased by ABEE, but that of NOS-2, a inducible enzyme, was constant. It was also found that the level of Nrf-2, a transcription factor of SOD, was increased by ABEE. Therefore, these results demonstrate that ABEE could promote blood circulation via above actions, suggesting that may be helpful for health of blood vessel.

Pharmaco-proteomics opportunities for individualizing neurovascular treatment

Neurovascular disease often involves multi-organ system injury. For example, patent foramen ovale (PFO) related ischemic strokes involve not just the brain, but also the heart, the lung, and the peripheral vascular circulation. For higher-risk but high-reward systemic therapy (e.g., thrombolytics, therapeutic hypothermia (TH), PFO closure) to be implemented safely, very careful patient selection and close monitoring of disease progression and therapeutic efficacy are imperative. For example, more than a decade after the approval of therapeutic hypothermic and intravenous thrombolysis treatments, they both remain extremely under-utilized, in part due to lack of clinical tools for patient selection or to follow therapeutic efficacy. Therefore, in understanding the complexity of the global effects of clinical neurovascular diseases and their therapies, a systemic approach may offer a unique perspective and provide tools with clinical utility. Clinical proteomic approaches may be promising to monitor systemic changes in complex multi-organ diseases – especially where the disease process can be ‘sampled’ in clinically accessible fluids such as blood, urine, and CSF. Here, we describe a ‘pharmaco-proteomic’ approach to three major challenges in translational neurovascular research directly at bedside – in order to better stratify risk, widen therapeutic windows, and explore novel targets to be validated at the bench – (i) thrombolytic treatment for ischemic stroke, (ii) therapeutic hypothermia for post-cardiac arrest syndrome, and (iii) treatment for PFO related paradoxical embolic stroke. In the future, this clinical proteomics approach may help to improve patient selection, ensure more precise clinical phenotyping for clinical trials, and individualize patient treatment.

Thermic effects of acupuncture on Taixi ( Kl 3) evaluated by means of infrared telethermography

ObjectiveTo observe the eventual thermic effects of stimulating Tàixī (▪ Kl 3) by telethermography. MethodsNine individuals of both sexes, chosen randomly, participated in this study. The temperature of the room where the experiment was carried out was not above 21 °C. At the start of the experiment the volunteer stayed for exactly ten minutes in the room for acclimatization, then the first thermographic image was recorded for standardization purposes. Following this, an acupuncture needle was inserted at Kl 3 only in the right leg, whose depth was limited to obtain Deqi, only manual stimulation for 15 min permanence in the site. After this period, new images were recorded. ResultsSignificant reduction of all the right leg temperatures, by about 1.1 °C in all the volunteers that received the acupuncture at the Kl 3 was noted, with a coefficient variation of P<0.0001 that was statistically highly significant, while on the other not stimulated leg the variation that occurred was around 0.7 °C, with no significant coefficient variation of P>0.05. ConclusionThe results of this study demonstrate that manual stimulation of the Kl 3 influences significantly peripheral vascular circulation, by means of sympathetic stimulation causing vasoconstriction.

Repair of bone defect by using vascular bundle implantation combined with Runx II gene-transfected adipose-derived stem cells and a biodegradable matrix

A large hurdle in orthopedics today is the difficulty of dealing with the non-union of fractured bones. We therefore evaluated the effects of runt-related transcription factor II (Runx II), a factor used to create gene-modified tissue-engineered bone, combined with vascular bundle implantation for repairing segmental bone defects. Adenovirus Runx II gene (Ad-Runx II)-modified rabbit adipose-derived stem cells (ADSCs) were seeded onto polylactic acid/polycaprolacton (PLA/PCL) scaffolds to construct gene-modified tissue-engineered bone. The following four methods were used for repair in rabbit radial-defect (1.5 cm long) models: gene-modified tissue-engineered bone with vascular bundle (Group A), gene-modified tissue-engineered bone (Group B), non-gene-modified tissue-engineered bone with vascular bundle (Group C), and PLA/PCL scaffolds only (Group D). X-ray, histological examination, biomechanics analysis, and micro-angiography were conducted 4, 8, and 12 weeks later to determine angiogenesis and osteogenesis. The volume and speed of production of newly formed bones in Group A were significantly superior to those in other groups, and de-novo vascular network circulation from the vessel bundle through newly formed bone tissue was observed, with the defect being completely repaired. Group B showed a slightly better effect in terms of speed and quality of bone formation than Group C, whereas the bone defect in Group D was replaced by fibrous tissue. The maximal anti-bending strength in Group A was significantly higher than that in the other groups. Runx II gene therapy combined with vascular bundle implantation thus displays excellent abilities for osteoinduction and vascularization and is a promising method for the treatment of bone non-union and defect.

Interstitial Fluid Balance Resulting from Intestinal‐Hepatic Interaction

The anatomical interconnections between the liver and intestines make interstitial fluid balance complex and experimental data exceedingly difficult to interpret. The portal vein connects the intestinal and hepatic blood circulations, and the cisterna chyli connects the intestinal and hepatic lymphatic systems. Furthermore, mathematical models designed to relate interstitial volumes and lymph flows to critical parameters either oversimplify the lymphatic system or overcomplicate the vascular system. Therefore, we developed a model that predicts interstitial pressures and lymph flows by adjusting the relative complexity of the lymphatic and vascular circulations. First, microvascular filtration was characterized by the Starling‐Landis equation. Second, lymphatic flow was made more realistic by assuming it to be more sensitive to inlet than outlet pressure. Third, blood flows were characterized by arterial, venous, and portal resistances. Finally, linearization and judicious use of simplifying assumptions yielded simple, algebraic solutions for interstitial pressures and lymph flows. The resulting model is comprehensive enough to reproduce conditions as diverse as interstitial edema, ascites formation, and changes in lymph flow, resulting from as diverse stimuli as inflammation, portal hypertension, hemodilution, and elevated central venous pressure.

Nanotheranostics of Circulating Tumor Cells, Infections and Other Pathological Features in Vivo

Many life-threatening diseases are disseminated through biological fluids, such as blood, lymph, and cerebrospinal fluid. The migration of tumor cells through the vascular circulation is a mandatory step in metastasis, which is responsible for ∼90% of cancer-associated mortality. Circulating pathogenic bacteria, viruses, or blood clots lead to other serious conditions including bacteremia, sepsis, viremia, infarction, and stroke. Therefore, technologies capable of detecting circulating tumor cells (CTCs), circulating bacterial cells (CBCs), circulating endothelial cells (CECs), circulating blood clots, cancer biomarkers such as microparticles and exosomes, which contain important microRNA signatures, and other abnormal features such as malaria parasites in biological fluids may facilitate early diagnosis and treatment of metastatic cancers, infections, and adverse cardiovascular events. Unfortunately, even in a disease setting, circulating abnormal cells are rare events that are easily obscured by the overwhelming background material in whole blood. Existing detection methods mostly rely on ex vivo analyses of limited volumes (a few milliliters) of blood samples. These small volumes limit the probability of detecting CTCs, CECs, CBCs and other rare phenomena. In vivo detection platforms capable of continuously monitoring the entire blood volume may substantially increase the probability of detecting circulating abnormal cells and, in particular, increase the opportunity to identify exceedingly rare and potentially dangerous subsets of these cells, such as circulating cancer stem cells (CCSCs). In addition, in vivo detection technologies capable of destroying and/or capturing circulating abnormal cells may inhibit disease progression. This review focuses on novel therapeutic and diagnostic (theranostic) platforms integrating in vivo real-time early diagnosis and nano-bubble based targeted therapy of CTCs, CECs, CBCs and other abnormal objects in circulation. This critical review particularly focuses on nanotechnology-based theranostic (nanotheranostic) approaches, especially in vivo photoacoustic (PA) and photothermal (PT) nanotheranostic platforms. We emphasize an urgent need for in vivo platforms composed of multifunctional contrast nanoagents, which utilize diverse modalities to realize a breakthrough for early detection and treatment of harmful diseases disseminated through the circulation.

Tibetan Medicine: An Effective Botanical Supplement for Peripheral Vascular Circulation

This review provides an instructive example of how a botanical and mineral formula known in the tradition of Tibetan medicine as Gabyr-Nirynga (camphor combination), denoted as formula No. 28, has evolved into a contemporary application through scientific research. This developmental pathway has led to a standardized nutraceutical with clinically proven efficacy in alleviation of a form of atherosclerosis-peripheral arterial disease (PAD). The systematic scientific research began in Switzerland in 1970s and resulted in five, double-blind clinical studies conducted in various European countries on cardiovascular use of the formula. The formula’s mechanism of action has been described in Tibetan tradition based on its three groups of botanical and mineral ingredients: (1) main active ingredients, (2) auxiliary ingredients, and (3) components that offset the action of the first two groups and facilitate gastrointestinal absorption of the formula. Based on preclinical and clinical studies, several mechanisms of action relevant to alleviation of the PAD have been discussed, such as an increase in the threshold for platelet aggregation, lower total blood cholesterol and low-density lipoproteins (LDL), and prevention of blood lipid peroxidation. A study in an animal model of CNS inflammation, i.e. Experimental Allergic Encephalomyelitis (EAE), has shown that No. 28 can exert action as a biological response modifier improving response of the organism to chronic inflammation. This latter mechanism may be particularly relevant to the clinical benefits with No. 28 in patients with PAD, in view of cardiovascular disease increasingly considered as an outcome of a chronic inflammatory process. The integration of traditional knowledge of a botanical formula with science-derived pharmacology is referred in this paper as the Interactive Nutrients process.

Polymer cross-linking: a nanogel approach to enhancing the relaxivity of MRI contrast agents.

Polymer cross-linking was explored as an approach for increasing the relaxivity of macromolecular contrast agents for magnetic resonance imaging. Poly(ethylene glycol) methyl ether methacrylate, N-(2-aminoethyl)methacrylamide hydrochloride, and the cross-linker ethylene glycol dimethacrylate were copolymerized under free radical conditions. By tuning the cross-linker content and reaction concentration, it was possible to obtain 10 nm nanogels in a single synthetic step. The pendant amine moieties were functionalized with an isothiocyanate derivative of diethylenetriaminepentaacetic acid (DTPA) and Gd(iii) was chelated. In comparison with a linear control polymer prepared under the same conditions in the absence of the cross-linking agent, the nanogel contrast agent did exhibit enhanced relaxivity with an r1 of 20.8 ± 0.2 at 20 MHz and 17.5 ± 0.4 at 60 MHz (corresponding to the clinical field strength of 1.5 T). The nuclear magnetic resonance dispersion profile was modeled to demonstrate that the enhanced relaxivity was a result of the nanogel agent's increased rotational correlation time, that is proposed to result from the constraint on motion imparted by the cross-linking. T1 weighted imaging in mice showed enhanced contrast and vascular circulation for the nanogel relative to Gd(iii)-DTPA (Magnevist) demonstrating the future promise of these new agents.

The Impact of Asymmetric Dimethylarginine (ADAMA), the Endogenous Nitric Oxide (NO) Synthase Inhibitor, to the Pathogenesis of Gastric Mucosal Damage

This review was designed to provide an update on the role of asymmetric arginine (ADMA), the endogenous inhibitor of nitric oxide (NO) synthase in the pathophysiology of the upper gastrointestinal (GI) tract. Numerous studies in the past confirmed that NO is a multifunctional endogenous gas molecule involved in most of the body organs’ functional and metabolic processes including the regulation of gastrointestinal (GI) secretory functions, motility, maintenance of GI integrity, gastroprotection and ulcer healing. NO is metabolized from L-arginine by enzymatic reaction in the presence of constitutive NO synthase. In upper GI tract, NO acts as a potent vasodilator known to increase gastric mucosa blood flow, regulates the secretion of mucus and bicarbonate, inhibits the gastric secretion and protects the gastric mucosa against the damage induced by a variety of damaging agents and corrosive substances. In contrast, ADMA first time described by Vallance and coworkers in 1992, is synthesized by the hydrolysis of proteins containing methylated arginine amino acids located predominantly within the nucleus of cells. This molecule has been shown to competitively inhibit NO synthase suggesting its regulatory role in the functions of vascular endothelial cells and systemic circulation in humans and experimental animals. Nowadays, ADMA is a potentially important risk factor for coronary artery diseases and a marker of cardiovascular risk. Increased plasma levels of ADMA have been documented in several conditions that are characterized by endothelial dysfunction, including hypertension, hypercholesterolemia, hyperglycemia, renal failure and tobacco exposure. The role of ADMA in other systems including GI-tract has been so far less documented. Nevertheless, ADMA was shown to directly induce oxidative stress and cell apoptosis in gastric mucosal cells in vitro and to contribute to the inflammatory reaction associated with major human pathogen to gastric mucosa, Helicobacter pylori (H.pylori). Infection of gastric mucosa with this germ or H. pylori water extract led to marked increase in the plasma concentration of ADMA and significantly inhibited bicarbonate secretion, considered as one of the important components of upper GI-tract defense system. When administered to rodents, ADMA aggravated gastric mucosal lesions injury induced by cold stress, ethanol and indomethacin and this worsening effect on gastric lesions was accompanied by the significant increase in the plasma level of ADMA. This exaggeration of gastric lesions by ADMA was coincided with the inhibition of NO, the suppression of gastric blood flow and excessive release of proinflammatory cytokine TNF-α. This metabolic analog of L-arginine applied to rats was exposed to water immersion and restraint stress and ischemiareperfusion, causing an elevation of plasma levels of ADMA and gastric MDA content, which is the marker of lipid peroxidation. These effects, including the rise in the plasma levels of ADMA in rats with stress and ischemia-reperfusion-induced gastric lesions, were attenuated by concomitant treatment with L-arginine, the substrate for NO-synthase, and superoxide dismutase (SOD), a reactive oxygen metabolite scavenger added to ADMA. We conclude that ADMA could be considered as an important factor contributing to the pathogenesis of gastric mucosal damage and inflammatory reaction in H. pylori-infected stomach due to inhibition of NO, suppression of GI microcirculation, and the proinflammatory and proapoptotic actions of this arginine analog.

Persistent Polyuria in a Rat Spinal Contusion Model

Polyuria contributes to bladder overdistention, which confounds both lower and upper urinary tract management in individuals having a spinal cord injury (SCI). Bladder overdistention post-SCI is one of the most common triggers for autonomic dysreflexia, a potentially life-threatening condition. Post-SCI polyuria is thought to result from loss of vascular tone in the lower extremities, leading to edema and subsequent excess fluid, resulting in polyuria. Mild SCIs that have near complete recovery would therefore be expected to have little to no polyuria, while severe injuries resulting in flaccid limbs and lower extremity edema would be expected to exhibit severe polyuria. Since interventions that may decrease lower extremity edema are recommended to lessen the severity of polyuria, step training (which promotes vascular circulation) was evaluated as a therapy to reduce post-SCI polyuria. In the present study, polyuria was evaluated in mild, moderate, and severe contusive SCI in adult male rats. The animals were housed in metabolic cages for 24-hour periods pre- and post-SCI (to 6 weeks). Urine, feces, food, water, and body weights were collected. Other assessments included residual expressed urine volumes, locomotor scoring, in-cage activity, and lesion histology. SCI produced an immediate increase in 24-hour urine collection, as early as 3 days post-SCI. Approximately 2.6-fold increases in urine collection occurred from weeks 1-6 post-SCI for all injury severities. Even with substantial gains in locomotor and bladder function following a mild SCI, polyuria remained severe. Step training (30 min/day, 6 days/week) did not alleviate polyuria in the moderate SCI contusion group. These results indicate that (1) mild injuries retaining weight-bearing locomotion that should have mild, if any, edema/loss of vascular tone still exhibit severe polyuria, and (2) step training was unable to reduce post-SCI polyuria. Taken together, these results indicate that the current mechanistic hypothesis of post-SCI polyuria may be incomplete.

Antibodies to the α1-adrenergic receptor cause vascular impairments in rat brain as demonstrated by magnetic resonance angiography.

BackgroundCirculating agonistic autoantibodies acting at G protein-coupled receptors have been associated with numerous sever pathologies in humans. Antibodies directed predominantly against the α1-adrenergig receptor were detected in patients suffering from widespread diseases such as hypertension and type 2 diabetes. Their deleterious action has been demonstrated for peripheral organs. We postulate that antibodies to the α1-adrenergig receptor are relevant pathomolecules in diseases of the central nervous system associated with vascular impairments.Methodology/Principal FindingsUsing a rat model we studied the long-term action of antibodies against the α1-adrenergig receptor either induced by immunization with a receptor peptide or applied by intravenous injection. The vasculature in the rat brains was investigated by time-of-flight magnetic resonance angiography using a 9.4 Tesla small animal MR imaging system. Visual examination of maximum-intensity-projections (MIPs) of brain angiographs revealed the development of vascular defects in antibody- exposed animals between three and eight months of treatment. Relative vascular areas were derived from representative MIP image sections by grayscale analysis and used to form an index of vascular circulation. Animals exposed to the action of α1-adrenergig receptor antibodies showed significantly reduced vascular areas (p<0.05). Calculated index values indicated attenuated blood flow in both antibody-treated cohorts compared to their respective controls reaching with (relative units ± standard error, n = 10) 0.839±0.026 versus 0.919±0.026 statistical significance (p<0.05) for peptide-immunized rats.Conclusion/SignificanceWe present evidence that antibodies to the α1-adrenergig receptor cause cerebrovascular impairments in the rat. Our findings suggest the pathological significance of these antibodies in pathologies of the human central nervous system linked to impairments of brain vasculature such as stroke and dementia.

Fluid Flow along Venous Adventitia in Rabbits: Is It a Potential Drainage System Complementary to Vascular Circulations?

BackgroundOur previous research and other studies with radiotracers showed evidence of a centripetal drainage pathway, separate from blood or lymphatic vessels, that can be visualized when a small amount of low molecular weight tracer is injected subcutaneously into a given region on skin of humans. In order to further characterize this interesting biological phenomenon, animal experiments are designed to elucidate histological and physiologic characteristics of these visualized pathways.MethodsMultiple tracers are injected subcutaneously into an acupuncture point of KI3 to visualize centripetal pathways by magnetic resonance imaging or fluorescein photography in 85 healthy rabbits. The pathways are compared with venography and indirect lymphangiography. Fluid flow through the pathways is observed by methods of altering their hydrated state, hydrolyzing by different collagenases, and histology is elucidated by optical, fluorescein and electron microscopy.ResultsHistological and magnetic imaging examinations of these visualized pathways show they consist of perivenous loose connective tissues. As evidenced by examinations of tracers’ uptake, they appear to function as a draining pathway for free interstitial fluid. Fluorescein sodium from KI3 is found in the pathways of hind limbs and segments of the small intestines, partial pulmonary veins and results in pericardial effusion, suggesting systematical involvement of this perivenous pathway. The hydraulic conductivity of these pathways can be compromised by the collapse of their fiber-rich beds hydrolyzed by either of collagenase type I, III, IV or V.ConclusionsThe identification of pathways comprising perivenous loose connective tissues with a high hydraulic conductivity draining interstitial fluid in hind limbs of a mammal suggests a potential drainage system complementary to vascular circulations. These findings may provide new insights into a systematically distributed collagenous connective tissue with a circulatory function and their potential relevance to the nature of acupuncture meridians.

A gas that ignites a bright spark

Modulation of vascular tone has been subject to intense investigations for more than three decades. Numerous studies have looked into signalling pathways where interaction between endothelial cells (ECs) and smooth muscle cells (SMCs) regulates the vascular circulation. This signalling induces SMC contraction/relaxation which is dependent on cytosolic calcium ([Ca2+]i) concentrations and investigations on how this [Ca2+]i level is regulated has opened up myriad upstream signalling routes. Probably most importantly, the discovery of the endothelium-derived relaxing factor (EDRF) in 1980 (Furchgott & Zawadzki, 1980) and its identification as the gasotransmitter nitric oxide (NO) in 1987 (Palmer et al. 1987) broadened our understanding of regulation of vascular tone. Since then, other freely diffusible endogenous gasotransmitters have been identified, namely carbon monoxide (CO) and hydrogen sulfide (H2S). However, NO and CO (although less efficient than NO) can exert their effects though activation of soluble guanylyl cyclase and subsequent production of cGMP, whereas H2S does not. All of these gasotransmitters exhibit strong cytotoxic properties when reaching higher levels and are also involved in non-vascular signalling pathways, i.e. in nervous or immune systems, and are important signalling molecules in certain disease conditions (Steinert et al. 2010; Skovgaard et al. 2011). Work published by Liang et al. (2012) in a recent issue of The Journal of Physiology describes more evidence for the vascular actions of H2S. The study elegantly shows how H2S modulates Ca2+ signalling in pig cerebral arteriolar SMCs by increasing Ca2+ spark frequency, which ultimately decreases global [Ca2+]i concentrations. The authors suggest that H2S enhances levels of ryanodine receptor (RyR)-sensitive Ca2+ stores and increases the frequency of calcium sparks and transient Ca2+-activated K+ channel (BK) currents leading to SMC hyperpolarization and subsequent vessel relaxation. Single channel analyses revealed that the increased frequencies of transient BK currents are not matched by changes in single channel current amplitudes but are solely due to greater open probability. SR Ca2+ content depends on the fine balance between SR uptake and release (Bassani et al. 1995) and it would be interesting to continue this study to determine whether H2S can regulate Ca2+ uptake mechanisms, such as sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) activities or other store release pathways, such as inositol 1,4,5-trisphosphate (IP3) receptor signalling. As RyR-mediated Ca2+ release provides the main pathway for Ca2+ sparks, the questions now arises which of the reported Ca2+ release routes are affected by H2S, including single RyR within release clusters without activation of the remaining channels, isolated un-clustered RyRs or non-RyR leak pathways. H2S is produced in various tissues, including the nervous and cardiovascular systems, from l-cysteine, catalysed by cystathionine-β-synthase (CBS) and/or cystathionine-γ-lyase (CSE). More recently, additional pathways have been identified cysteine aminotransferase (CAT) and 3-mercaptopyrovate sulfuresterase (3MST) with CSE being expressed in the SMCs and ECs but CAT/3MST only localized in the endothelium (Fig. 1). Depending on its concentration, H2S induces variable vasoactive effects in different vascular beds. The liver has high H2S-generating capacity and may be responsible for maintaining the concentration of H2S in the blood, which has been reported to be in the range of 1–160 μmol l−1 although the detection methods do not always give consistent results. Figure 1 Schematic diagram of gasotransmitter signalling in the vasculature Similarly to NO, exogenous application of H2S donors leads to a peak release of H2S followed by rapid metabolism and drop of vasoactive concentrations thereby altering its potential to induce relaxation over time. The complexity and concentration dependency of H2S signalling becomes apparent when comparing vasorelaxing and vasoconstricting effects (reviewed by Skovgaard et al. 2011). In light of these difficulties, an approach where endogenously produced H2S is investigated might help to explain observed inconsistent vascular responses to different H2S concentrations. H2S donor application relaxes rat aortic rings or human mammary arteries via opening of ATP-sensitive K+ (KATP) channels (Zhao et al. 2001) and direct actions of H2S on KATP channels have been reported. In addition H2S modulates voltage-gated K+ (KCNQ) and BK currents in various preparations; however, the exact mechanisms by which H2S acts on BK have to be elucidated. Discrepancies in modulatory effects on BK are most likely due to different concentrations used or tissue variability, which accounts for differences in BK α- and β-subunit expression. The current paper by Liang et al. (2012) provides new insights into the mechanisms by which BK channels are regulated in response to H2S signalling, namely via enhancing Ca2+ spark frequency. Nevertheless, the ultimate response of SMCs is the reduction of voltage-gated Ca2+ channel open probability in order to achieve vascular relaxation and the study by Liang et al. (2012) greatly enhances our understanding of vascular signalling pathways downstream of H2S.

Daily Use of Sildenafil Improves Endothelial Function in Men With Type 2 Diabetes

Diminished vascular endothelial function results in decreased vasodilator capacity and is associated with erectile dysfunction (ED) in patients afflicted with type 2 diabetes. The current study was designed to evaluate whether daily use of sildenafil could alter endothelial function and improve penile rigidity in a group of patients with diabetic ED. A double-blind, placebo-controlled, prospective trial was conducted with 24 men with type 2 diabetes who were randomized into 2 groups: one receiving daily sildenafil (50 mg, n = 12) and the other placebo (n = 12) for 10 weeks. Erectile function was captured subjectively using the International Index of Erectile Function (IIEF-5), and endothelial function was objectively monitored via brachial artery flow-mediated dilation. Among the placebo and sildenafil groups, there were no significant differences in average patient age, time from type 2 diabetes diagnosis, duration of ED, or baseline IIEF-5 scores. Past medical histories, including smoking, alcohol consumption, hypertension, and hyperlipidemia, were also similar. At the conclusion of the 10-week trial, patients who received daily sildenafil had significantly improved erectile rigidity as captured by IIEF-5 (P < .001) and increased endothelial function via brachial artery flow-mediated dilation (P < .01). Endothelial function in men with type 2 diabetes was enhanced with daily sildenafil. Improved erectile rigidity and enhanced vascular circulation was noted after 10 weeks of daily sildenafil use.

ACARDIAC ANCEPS FETUS- A CASE REPORT

An interesting rare case of lethal fetopathy is described. This case is based on morphological and histological confirmation. Fetus acardius is a parasite for its vascular circulation from the donor twin. The twin reversed arterial perfusion syndrome is an extremely rare manifestation of feto-fetal transfusion in twin pregnancy where the affected twin receives retrograde vascular supply from the healthy twin. Acardiac twin syndrome is a rare complication affecting monozygotic twins where one twin fails to have normal development. In this report we present an acardiac anceps fetus seen at term gestation and delivered by caesarean section, the other twin is a healthy, well formed baby. At the time of caesarean section, the live baby was delivered first and as the placenta was extracted, the malformed fetus was attached to the chorionic plate of the same placenta. A thin cord with one vascular channel was the only communication between placenta and malformed fetus which was later delivered and collected for the study.

Intravascular recovery of VWF and FVIII following intraperitoneal injection and differences from intravenous and subcutaneous injection in mice

Intravenous infusion studies in humans suggest that both von Willebrand factor (VWF) and factor VIII (FVIII) remain intravascular in contrast to other coagulation proteins. We explored whether infusion of VWF and FVIII by either intraperitoneal (i.p.) or subcutaneous (s.c.) injection would result in efficient absorption of these large proteins into the vascular circulation. FVIII(null) or VWF(null) mice were infused with plasma-derived or recombinant VWF and/or FVIII by i.p., s.c., or intravenous (i.v.) injection. Both VWF and FVIII were absorbed into the blood circulation after i.p. injection with a peak between 2 and 4 h at levels similar to those observed in mice infused intravenously. In contrast, neither VWF nor FVIII was detected in the plasma following s.c. injection. Although i.v. injection achieved peak plasma levels quickly, both human VWF and FVIII rapidly decreased during the first 2 h following i.v. injection. Following both i.v. and i.p. infusion of VWF, the multimeric structure of circulating VWF was similar to that observed in the infusate. These results demonstrate that both VWF and FVIII can be efficiently absorbed into the blood circulation following i.p., but not s.c. injection, indicating that i.p. administration could be an alternative route for VWF or FVIII infusion.

High resolution ultrasound evaluation of synovial thickness as a marker to assess response to deep tissue heating for pain relief in knee osteoarthritis

<b>Background:</b> High-resolution ultrasound (HRUS) is a useful tool in assessing synovial tissue response to deep tissue heating (DTH)/short wave diathermy (SWD) for pain relief in knee osteoarthritis. Shortwave (SW) diathermy can be used to improve vascular circulation and reduce inflammation and pain in patients with osteoarthritis. The purpose of this study was to assess the role of ultrasound in investigating whether repetitive SW diathermy, could reduce synovial thickening in patients with knee osteoarthritis. <b>Materials and Methods:</b> Synovial thickness measurement of superior, medial, and lateral patellar recesses was done using ultrasonography over a span of nineteen months from April 2010 to Nov 2011 following three sessions of short wave diathermy. The sum of these three measurements was taken as the total synovial thickness and pre and post test analysis was done using primer statistical software. <b>Result:</b> Synovial thickening continued to become significantly thinner with sessions of treatment and after the twelfth SW diathermy treatment, there was 20.58% reduction in the synovial thickening. <b>Conclusion:</b> Synovial thickness is a sensitive marker in gauging the response to short wave diathermy therapy. Synovial thickness is an objective marker to assess pain relief in knee osteoarthritis following deep tissue heating.

IFPA Meeting 2011 workshop report II: Angiogenic signaling and regulation of fetal endothelial function; placental and fetal circulation and growth; spiral artery remodeling

Workshops are an important part of the IFPA annual meeting as they allow for discussion of specialized topics. At IFPA meeting 2011 there were twelve themed workshops, three of which are summarized in this report. These workshops related to vascular systems and circulation in the mother, placenta and fetus, and were divided in to 1) angiogenic signaling and regulation of fetal endothelial function; 2) placental and fetal circulation and growth; 3) spiral artery remodeling.

Use of Fraction Flow Reserve to Predict Changes over Time in Management of Superficial Femoral Artery

Peripheral arterial disease is a condition characterized by progressive arterial narrowing, which affects patients' quality of life. The purposes of this study were to (1) establish the feasibility of obtaining peripheral fractional flow reserve (pFFR) in the peripheral vascular circulation, (2) demonstrate an association between baseline pFFR and peak systolic velocity (PSV) measured by duplex ultrasound, and (3) correlate postintervention pFFR with future restenosis using the change in PSV over time as a surrogate. Twenty patients underwent baseline ankle brachial index (ABI) and PSV testing. Pre- and postintervention pFFR was performed. Patients were followed with three ABI and PSV recordings during the 1 year follow-up period. The association between baseline PSV, ABI, and pFFR with changes in PSV over time were explored. Predictors of postprocedural PSV over time were determined. The baseline translesional-resting ratio was significantly different from the pFFR using adenosine (0.79 ± 0.08 vs. 0.71 ± 0.09, P = 0.01). Baseline PSV was significantly associated with preintervention pFFR (-0.77, P < 0.001). Compared to patients with a postprocedure pFFR > 0.95, patients with a postprocedure pFFR < 0.95 had a significantly more rapid rise in PSV over time (P = 0.009). This is the first study to demonstrate that the peripheral vascular bed does respond to vasodilatation thereby supporting the use of pFFR for this procedure. In our study, postintervention pFFR < 0.95 predicted a more rapid increase in PSV over time, which is a reasonably accepted surrogate for restenosis.