Effects of ambient particulate matter on vascular tissue: a review

Fine and ultra-fine particulate matter (PM) are major constituents of urban air pollution and recognized risk factors for cardiovascular diseases. This review examined the effects of PM exposure on vascular tissue. Specific mechanisms by which PM affects the vasculature include inflammation, oxidative stress, actions on vascular tone and vasomotor responses, as well as atherosclerotic plaque formation. Further, there appears to be a greater PM exposure effect on susceptible individuals with pre-existing cardiovascular conditions.

Combined Red Clover isoflavones and probiotics potently reduce menopausal vasomotor symptoms

Background

Natural estrogen decline leads to vasomotor symptoms (VMS). Hormone therapy alleviates symptoms but increases cancer risk. Effective treatments against VMS with minimal cancer risks are needed. We investigate the effects of a highly bioavailable aglycone rich Red Clover isoflavone treatment to alleviate existing menopausal VMS, assessed for the first time by 24hour ambulatory skin conductance (SC)

Methods and results

We conducted a parallel, double blind, randomised control trial of 62 peri-menopausal women aged 40–65, reporting ≥ 5 hot flushes/day and follicle stimulating hormone ≥35 IU/L. Participants received either twice daily treatment with bioavailable RC extract (RCE), providing 34 mg/d isoflavones and probiotics, or masked placebo formulation for 12 weeks. The primary outcome was change in daily hot flush frequency (HFF) from baseline to 12 weeks using 24hr SC. Secondary outcomes were change in SC determined hot flush intensity (HFI), self-reported HFF (rHFF) and hot flush severity (rHFS), blood pressure and plasma lipids. A significant decrease in 24hr HFF (P < 0.01) and HFI (P<0.05) was found when comparing change from baseline to 12 months of the RCE (-4.3 HF/24hr, CI -6.8 to -2.3; -12956 μS s^-1, CI -20175 to -5737) with placebo (0.79 HF/24hr, CI -1.56 to 3.15; 515 μS s^-1, CI -5465 to 6496). rHFF was also significantly reduced (P <0.05)in the RCE (-2.97 HFs/d, CI -4.77 to -1.17) group compared to placebo (0.036 HFs/d, CI -2.42 to 2.49). Other parameters were non-significant. RCE was well tolerated.

Conclusion

Results suggest that moderate doses of RCE were more effective and superior to placebo in reducing physiological and self-reported VMS. Findings support that objective physiological symptom assessment methods should be used together with self-report measures in future studies on menopausal VMS.

Trial registration

ClinicalTrials.gov NCT02028702

Cyclooxygenase inhibition improves endothelial vasomotor dysfunction of visceral adipose arterioles in human obesity

OBJECTIVE

The purpose of this study was to determine whether cyclooxygenase inhibition improves vascular dysfunction of adipose microvessels from obese humans.

DESIGN AND METHODS

In 20 obese subjects (age 37 ± 12 years, BMI 47 ± 8 kg/m²), subcutaneous and visceral fat were collected during bariatric surgery and characterized for adipose depot-specific gene expression, endothelial cell phenotype, and microvascular function. Vasomotor function was assessed in response to endothelium-dependent agonists using videomicroscopy of small arterioles from fat.

RESULTS

Arterioles from visceral fat exhibited impaired endothelium-dependent, acetylcholine-mediated vasodilation, compared to the subcutaneous depot (P < 0.001). Expression of mRNA transcripts relevant to the cyclooxygenase pathway was upregulated in visceral compared to subcutaneous fat. Pharmacological inhibition of cyclooxygenase with indomethacin improved endothelium-dependent vasodilator function of arterioles from visceral fat by twofold (P = 0.01), whereas indomethacin had no effect in the subcutaneous depot. Indomethacin increased activation via serine-1177 phosphorylation of endothelial nitric oxide synthase in response to acetylcholine in endothelial cells from visceral fat. Inhibition of endothelial nitric oxide synthase with N(ω)-nitro-L-arginine methyl ester abrogated the effects of cyclooxygenase-inhibition suggesting that vascular actions of indomethacin were related to increased nitric oxide bioavailability.

CONCLUSIONS

Our findings suggest that cyclooxygenase-mediated vasoconstrictor prostanoids partly contribute to endothelial dysfunction of visceral adipose arterioles in human obesity.

[Immunolocalization of hemeoxygenase-2 in neurons of the human vasomotor center in arterial hypertension]

We studied the immunolocalization of hemeoxygenase-2 in neurons of the medulla oblongata in men (n=8), aged 18-44 years, who died from causes unrelated to the injury of the central nervous system and in people with the lifetime diagnosis of hypertension (n=6). It has been found that neurons with enzyme positive reaction are present in all parts of the medulla oblongata with concentrations ranging from 0.5 to 13.7% of the total number of cells. The high proportion of small neurons with the high or moderate density of deposits was found in the sensory nuclei. Large cells of the motor nuclei often exhibit the negative or low intensity of the enzymatic reaction. In arterial hypertension, a decrease in the proportion AH NO-positive neurons and the average optical density of the reaction product was noted. The reduction was seen in most affected neurons in the rostral part of the solitary tract nucleus and the lateral reticular nucleus. In the motor nuclei and in the dorsal nucleus of the vagus nerve, these parameters decreased as well although the reduction was not as great as observed in the sensory nuclei.

Role of reactive oxygen and nitrogen species in the vascular responses to inflammation

Inflammation is a complex and potentially life-threatening condition that involves the participation of a variety of chemical mediators, signaling pathways, and cell types. The microcirculation, which is critical for the initiation and perpetuation of an inflammatory response, exhibits several characteristic functional and structural changes in response to inflammation. These include vasomotor dysfunction (impaired vessel dilation and constriction), the adhesion and transendothelial migration of leukocytes, endothelial barrier dysfunction (increased vascular permeability), blood vessel proliferation (angiogenesis), and enhanced thrombus formation. These diverse responses of the microvasculature largely reflect the endothelial cell dysfunction that accompanies inflammation and the central role of these cells in modulating processes as varied as blood flow regulation, angiogenesis, and thrombogenesis. The importance of endothelial cells in inflammation-induced vascular dysfunction is also predicated on the ability of these cells to produce and respond to reactive oxygen and nitrogen species. Inflammation seems to upset the balance between nitric oxide and superoxide within (and surrounding) endothelial cells, which is necessary for normal vessel function. This review is focused on defining the molecular targets in the vessel wall that interact with reactive oxygen species and nitric oxide to produce the characteristic functional and structural changes that occur in response to inflammation. This analysis of the literature is consistent with the view that reactive oxygen and nitrogen species contribute significantly to the diverse vascular responses in inflammation and supports efforts that are directed at targeting these highly reactive species to maintain normal vascular health in pathological conditions that are associated with acute or chronic inflammation.

[Forensic medical characteristic of the neurovascular apparatus in the case of spinal cord injury]

This paper is devoted to the analysis of the results of the author's investigations concerning spinal cord injuries. The voluminous material obtained with the use of up-to-date research methods (histological, histochemical, and biochemical) includes basic data on the mechanisms of regulation of blood circulation under normal conditions and in the case of a mechanical injury. It is shown that pathological morphological changes in the affected areas of the spinal cord as well as activities of transport enzymes in the capillaries and the reactive processes in the monoaminoergic nervous apparatus of he arteries may be used as the objective criteria for the determination of the time of the injury. The results of these studies find application in the practical diagnostic work for the estimation of the time of the spinal cord injury.

NO-positive neurons in some nuclei of human bulbar vasomotor center in arterial hypertension

The distribution of nitroxidergic neurons and activities of neuronal NO synthase in them in some nuclei of the bulbar vasomotor center were studied in patients with early forms of arterial hypertension. Activity of neuronal NO synthase is reduced significantly in the majority of nuclei in patients with early forms of arterial hypertension, while the content of NO-positive cells was only slightly changed. More pronounced changes in this parameter were detected in the solitary tract nuclei in comparison with the reticular formation nuclei, which had efferent relationships with the intermediate lateral spinal nucleus.

The role of intranasal estradiol spray in the management of moderate to severe vasomotor symptoms in menopausal women

Hormone therapy (HT) is the most effective treatment at present available for climacteric symptoms. As harmful effects were highlighted in recent randomized clinical trials, the risk-benefit ratio does not favor the use of HT for prevention of cardiovascular diseases and bone fractures in postmenopausal women. Nevertheless, experimental and clinical trials suggest that adverse effects of HT basically depend on the estrogen and progestin formulation, dosage, route of administration, patient's age, associated diseases, and duration of treatment. All estrogen formulations and routes of administration have comparable beneficial effects on vasomotor and urogenital symptoms and on bone structure. But adverse effects may differ. Thus, cardiovascular and invasive breast cancer risks are higher with oral estrogen than with transdermal estradiol. However, transdermal estradiol is not free of inconveniences such as differences among individuals in absorption rates, loss of patches due to poor adhesion, and skin irritation. HT requires careful adjustment to each individual patient and continuous monitoring of clinical evolution. In the future, this adjustment and maybe the use of alternative routes such as intranasal could benefit from genetic screening to maximize in each individual the ratio between positive and adverse effects of HT.

[Efferent innervation of the arteries of human leptomeninx in arterial hypertension]

Structure of the efferent nerve plexuses (adrenergic, acetylcholinestherase- and cholinacetyltranspherase-positive, NO-dependent), was studied in the arteries of human leptomeninx with different diameters. Material was obtained from the corpses of the healthy people and of the patients with initial stages of arterial hypertension (AH). It was shown that the concentrations of cholinergic and adrenergic nerve fibers and varicosities in axon terminal part, innervating the arteries with the diameters ranging from 450 till 100 microm, were not significantly different. In these arteries, NO-ergic plexuses were also detected. In patients with AH, regardless the arterial diameters, the significant increase (up to 15-20%) of adrenergic nerve fiber and varicosity concentrations was found. The changes in cholinergic nerve fiber concentration were found to depend on the vessel diameter: the significant decrease of these parameter was observed only in arteries with the diameter of 100-200 microm. No significant changes in nerve plexus concentration was noticed in the arteries with greater or smaller diameter. In NO-ergic neural conductors, the enzyme activity decreased only in the large arteries, and remained almost unchanged in the small vascular branches. The changes in the vasomotor innervation described in AH, are interpreted as a vasomotor innervation dysfunction of the leptomeninx arteries that may result in the hemodynamic disturbances.

Compromised aortic vasoreactivity in male estrogen receptor-alpha-deficient mice during acute lipopolysaccharide-induced inflammation

Activation of the estrogen receptor-alpha (ERalpha) mediates the vasculoprotective effects of estrogen, in part, through modulating nitric oxide (NO) production and vasodilation. Whereas inflammation is accompanied by altered vascular reactivity and underlies the pathogenesis of vascular disease, the role of the ERalpha in the vascular responses associated with acute systemic inflammation remains poorly characterized. Contractile and relaxation responses of isolated aortic segments were investigated 12 h after ip injection of saline or lipopolysaccharide (LPS, 10 mg/kg) in male wild-type (ERalpha(+/+)) and ERalpha-deficient (ERalpha(-/-)) mice. As previously observed, LPS-injected ERalpha(+/+) mice displayed reduced contractile responses to phenylephrine and enhanced vasodilation in response to acetylcholine. In contrast, aortic tissues from LPS-injected ERalpha(-/-) mice displayed enhanced contractile responses and reduced sensitivity to acetylcholine- and sodium nitroprusside-induced vasodilation. LPS treatment in ERalpha(+/+) and ERalpha(-/-) mice resulted in similar increased levels of systemic NO production and inducible NO synthase expression in the vascular wall. However, expression of mRNA and protein for endothelial NOS and soluble guanylate cyclase (alpha- and beta-subunits) were significantly reduced in aortic tissues from LPS-treated ERalpha(-/-) animals, possibly accounting for reduced endothelial NO production and reduced smooth muscle responses to NO. These findings represent new evidence of the functional role of ERalpha in the male vasculature and suggest that during acute LPS-induced inflammatory responses, the ERalpha mediates the sustained expression of the molecular machinery essential for endothelial NO synthesis (i.e. endothelial NOS) and the vascular responses to NO (i.e. soluble guanylate cyclase).

The pain of fibromyalgia syndrome is due to muscle hypoperfusion induced by regional vasomotor dysregulation

Fibromyalgia syndrome (FMS) is a condition of chronic muscle pain and fatigue of unknown etiology and pathogenesis. There is limited support for the various hypotheses espoused to account for the manifestations of FMS, including immunogenic, endocrine, and neurological mechanisms. Treatment, partially effective at best, is directed toward symptomatic relief without the benefit of targeting known, underlying pathology. A noteworthy commonality among partially effective therapies is a vasodilatory effect. This is true both of conventional treatments, unconventional treatments such as intravenous micronutrient therapy, and lifestyle treatments, specifically graduated exercise. The pain of fibromyalgia is described in terms suggestive of the pain in muscles following extreme exertion and anaerobic metabolism. Taken together, these characteristics suggest that the pain could be induced by vasomotor dysregulation, and vasoconstriction in muscle, leading to low-level ischemia and its metabolic sequelae. Vasodilatory influences, including physical activity, relieve the pain of FMS by increasing muscle perfusion. There are some preliminary data consistent with this hypothesis, and nothing known about FMS that refutes it. The hypothesis that the downstream cause of FMS symptoms is muscle hypoperfusion due to regional vasomotor dysregulation has clear implications for treatment; is testable with current technology; and should be investigated.

Intensive insulin therapy protects the endothelium of critically ill patients

The vascular endothelium controls vasomotor tone and microvascular flow and regulates trafficking of nutrients and biologically active molecules. When endothelial activation is excessive, compromised microcirculation and subsequent cellular hypoxia contribute to the risk of organ failure. We hypothesized that strict blood glucose control with insulin during critical illness protects the endothelium, mediating prevention of organ failure and death. In this preplanned subanalysis of a large, randomized controlled study, intensive insulin therapy lowered circulating levels of ICAM-1 and tended to reduce E-selectin levels in patients with prolonged critical illness, which reflects reduced endothelial activation. This effect was not brought about by altered levels of endothelial stimuli, such as cytokines or VEGF, or by upregulation of eNOS. In contrast, prevention of hyperglycemia by intensive insulin therapy suppressed iNOS gene expression in postmortem liver and skeletal muscle, possibly in part via reduced NF-kappaB activation, and lowered the elevated circulating NO levels in both survivors and nonsurvivors. These effects on the endothelium statistically explained a significant part of the improved patient outcome with intensive insulin therapy. In conclusion, maintaining normoglycemia with intensive insulin therapy during critical illness protects the endothelium, likely in part via inhibition of excessive iNOS-induced NO release, and thereby contributes to prevention of organ failure and death.

Paroxysmal apnea and vasomotor instability following medullary infarction

BACKGROUND

Central hypoventilation and paroxysmal hypertension are uncommon complications of medullary infarction. To our knowledge, the combination of these autonomic complications of medullary stroke has not previously been reported.

OBJECTIVE

To describe a patient who experienced life-threatening paroxysmal attacks of central apnea and vasomotor instability 3 months after medullary infarction, a combination of symptoms that is unusual. PATIENT, METHODS, AND RESULTS: Following a right lateral medullary infarction, an otherwise stable 70-year-old woman developed recurrent episodes of apnea (PCO2), > 100 mm Hg), blood pressure instability (systolic blood pressure, > 200 to < 100 mm Hg), and mental status changes (from agitation to coma) within hours of removal from mechanical ventilation. These attacks occurred repeatedly after removal from mechanical ventilation and were prevented by diaphragm pacing with a phrenic nerve pacemaker and nocturnal mechanical ventilation via a tracheostomy.

CONCLUSIONS

A syndrome of life-threatening central hypoventilation and vasomotor instability can occur after medullary infarction. Placement of a phrenic nerve pacemaker can prevent these complications, without the functional limitations imposed by continuous mechanical ventilation.

Lifestyle and demographic factors in relation to vasomotor symptoms: baseline results from the Study of Women's Health Across the Nation

Results of recent trials highlight the risks of hormone therapy, increasing the importance of identifying preventive lifestyle factors related to menopausal symptoms. The authors examined the relation of such factors to vasomotor symptoms in the multiethnic sample of 3,302 women, aged 42-52 years at baseline (1995-1997), in the Study of Women's Health Across the Nation (SWAN). All lifestyle factors and symptoms were self-reported. Serum hormone and gonadotropin concentrations were measured once in days 2-7 of the menstrual cycle. After adjustment for covariates using multiple logistic regression, significantly more African-American and Hispanic and fewer Chinese and Japanese than Caucasian women reported vasomotor symptoms. Fewer women with postgraduate education reported vasomotor symptoms. Passive exposure to smoke, but not active smoking, higher body mass index, premenstrual symptoms, perceived stress, and age were also significantly associated with vasomotor symptoms, although a dose-response relation with hours of smoke exposure was not observed. No dietary nutrients were significantly associated with vasomotor symptoms. These cross-sectional findings require further longitudinal exploration to identify lifestyle changes for women that may help prevent vasomotor symptoms.

Effects of smoking on nitric oxide synthesis in epicardial normal and atheromatous coronary arteries

The effects of an intracoronary infusion of N(G)-monomethyl-L-arginine (LNMMA) followed by intracoronary administration of nitroglycerin in non-stenotic proximal and distal coronary segments were studied in 11 patients with coronary artery disease and in 19 subjects with "normal arteriograms". In normal subjects, LNMMA induced significant constriction (p<0.01) of proximal and distal vessels in non-smokers and smokers. In normal non-smokers, the reduction in coronary luminal diameter of proximal segments was significantly greater compared to normal smokers (p<0.05). In patients with coronary artery disease, LNMMA induced significant constriction of proximal and distal vessels in smokers, and only distal constriction in non-smokers (p<0.01). The reduction in coronary luminal diameter of the distal segments in normal smokers, and in both groups in patients with coronary artery disease was significantly greater compared with proximal segments (p<0.05). Therefore, the difference in vasomotor response to LNMMA in relation to smoking is localised to the proximal coronary segments.

Coronary endothelial dysfunction is not rapidly reversible with ascorbic acid

In humans with cardiovascular risk factors, increased vascular production of superoxide anion may contribute to endothelial dysfunction by its reacting with nitric oxide and reducing its biological activity. High concentrations of ascorbic acid scavenge superoxide anion and restore normal endothelium-dependent vasodilation in humans with cardiovascular risk factors. To investigate the contribution of increased superoxide anion to endothelial dysfunction in atherosclerotic coronary arteries, we examined the effect of sequential infusions of ascorbic acid (final concentration 0.1, 1.0, and 10 mmol/L) or placebo on coronary endothelial function in 26 subjects referred for cardiac catheterization to evaluate coronary artery disease. Coronary vasomotor function was evaluated using intracoronary agonist infusion, quantitative angiography, and intracoronary Doppler measurements. At baseline, endothelium-dependent vasodilation of epicardial arteries and coronary microvessels was impaired to an equivalent extent in the ascorbic acid and placebo groups. Sequential ascorbic acid infusions had no effect on the acetylcholine-induced change in coronary artery diameter (-11+/-8, -12+/-10, and -9+/-9%) compared with the effect of placebo (-14+/-13, -16+/-10, and -13+/-9%) infusions (p=0.98). Similarly, the changes in coronary blood flow during acetylcholine infusions were equivalent during ascorbic acid (51+/-44, 67+/-66, and 62+/-52%) and placebo (61+/-104, 55+/-93, and 50+/-69%) infusions (p=0.63). Ascorbic acid also had no effect on the dilator response to intracoronary nitroglycerin (p=0.19). These data argue against an important role for superoxide-mediated "inactivation" of nitric oxide or another rapidly reversible form of oxidative stress as a mechanism of coronary endothelial dysfunction in patients with coronary atherosclerosis.

Descending Vasomotor Pathways in Humans: Correlation between Axonal Preservation and Cardiovascular Dysfunction after Spinal Cord Injury

Cardiovascular dysfunction is common after cervical spinal cord injury (SCI) in humans. At least three spinal cord elements involved in cardiovascular control have been identified: descending vasomotor pathways (DVPs), sympathetic preganglionic neurons, and spinal afferents. However, little is known about the localization of the DVPs within the human spinal cord, which limits our understanding of the mechanisms of cardiovascular dysfunction after SCI. This study was undertaken to examine the association of cardiovascular abnormalities after SCI in humans with the severity of degeneration and axonal loss within the DVPs. A detailed chart review and histopathological examination of postmortem spinal cord tissue was conducted in individuals with cervical SCI (n = 7) and control individuals with an intact central nervous system (n = 5). Individuals with SCI were divided into group 1 (severe cardiovascular abnormalities) and group 2 (no/minor cardiovascular disturbances). The area of degeneration and the number of preserved axons within different areas of the spinal cord were quantitated using EMPIX imaging software. Two areas of possible localization of DVPs were investigated: area I, within the dorsal aspects of the lateral funiculus; and area II, within the white matter adjacent to the dorsolateral aspect of the lateral horn. Comparison of the extent of axonal degeneration in both SCI groups demonstrated that individuals in group 1 had more extensive axonal degeneration than those in group 2. The number of intact axons within areas I and II in individuals from group 1 was significantly lower than those from group 2 or control cases (p = 0.029; p = 0.028). The most dramatic axonal loss was observed within area I in individuals with cardiovascular dysfunction. We conclude that loss and degeneration of DVPs, which are localized within the dorsolateral aspects of the human spinal cord, contributes to abnormal cardiovascular control after SCI. This information adds to our knowledge of pathobiology of cardiovascular dysfunction after human SCI and may ultimately suggest novel therapeutic strategies as regenerative and reparative approaches become translated to the clinic.

Vasomotor function of pig coronary arteries after chronic coronary occlusion

Placement of an ameroid constrictor in large-conduit pig coronary arteries causes progressive stenosis and distal myocardial ischemia. Blood perfusion in the ischemic region is partly dependent on vasomotor responses to neural and humoral factors distal to the occlusion site. To ascertain the degree of impairment of vascular function in pigs, the authors induced myocardial ischemia by placing an ameroid constrictor in the left circumflex coronary artery and examined vascular reactivity and histopathology distal to the constriction site. The sensitivity of the distal left circumflex coronary and nonoccluded control left anterior descending arteries to PGF(2alpha) was similar. After nitric oxide blockade using Nw-nitro-l-arginine methylester (l-NAME), the sensitivity and maximal contraction to PGF(2alpha) were significantly increased in both the left circumflex coronary (EC50: 5.86 +/- 0.74 vs. 3.28 +/- 0.84 microM; C(max): 4.63 +/- 0.28 vs. 6.25 +/- 0.30 g, P < 0.01) and left anterior descending (EC50: 6.57 +/- 0.73 vs. 2.78 +/- 0.16 microM; C(max): 5.09 +/- 0.37 vs. 6.95 +/- 0.39 g, P < 0.01) arteries. Substance P-induced relaxation (100 pM) was blocked to a larger degree in the distal left circumflex coronary artery when compared with the left anterior descending artery (76.9 +/- 4.2% vs. 56.4 +/- 3.1%, P < 0.05). Endothelium-independent relaxation to sodium nitroprusside was similar in the left circumflex coronary and left anterior descending arteries before and after nitric oxide blockade. Histopathologic examination showed no major differences between distal left circumflex coronary artery segments and left anterior descending artery controls. However, scanning electron microscopy showed endothelial hypertrophy and activation in specimens from the left circumflex coronary arteries. In summary, as a result of the major hemodynamic changes induced by a chronic constriction and eventual occlusion of a large coronary artery, distal segments underwent adaptive compensatory changes. Such compensation may be related to an increased nitric oxide production by the hypertrophic endothelium in response to alterations in coronary hemodynamics.

Cerebral vasomotor reactivity to postural change is impaired in patients with cerebrovascular white matter lesions

Vasomotor reactivity is decreased in terms of cerebral blood flow (CBF) response to hypercapnia in patients with cerebrovascular white matter (WM) lesions. This study evaluated whether vasomotor reactivity is altered during postural change in these patients. We examined 28 consecutive patients with cerebrovascular WM lesions, subgrouped into 19 with Schmidt scale 2 and 9 with scale 3 WM lesions. These patients were compared with 15 age-matched patients with lacunar infarction but without significant WM lesions and 6 controls without cerebrovascular disease. With blood pressure monitoring, brain SPECT scans were done in the supine and upright position using HMPAO as a tracer. The ratio of radioisotope (RI) counts in the frontal and parieto-temporal lobes to those in the cerebellar hemispheres (CBF ratio) was evaluated. In the comparison among the three groups, there were no significant differences in the changes of systemic blood pressure after rising. The baseline CBF ratio in the supine position was also not different among the three groups. After rising, the CBF ratio in each region of interest (ROI) did not change significantly in either lacunar infarction or control groups. By contrast, in patients with WM lesions, the CBF ratio in the frontal lobe decreased after rising (p < 0.0001). In the subgroup analysis, there was a significant increase in blood pressure 1, 2 and 3 min after rising (p < 0.05), with a higher tendency in the scale 3 WM lesion group as compared to the scale 2 WM lesion group. The CBF ratio was decreased in both frontal and parieto-temporal areas in the scale 2 WM lesion group, whereas this was significant only in the frontal areas in the scale 3 WM lesion group. Vasomotor reactivity is impaired in cerebrovascular WM lesions, suggesting a susceptibility to postural changes in these patients.

Immunohistochemical-scintigraphic correlation of sympathetic cardiac innervation in postischemic left ventricular aneurysms

BACKGROUND

This study was conceived to explore the correspondence between scintigraphic imaging of the sympathetic innervation of human postischemic left ventricular aneurysms and direct immunohistochemical localization of the nerve fibers in the same area.

MATERIALS AND METHODS

In 7 patients undergoing left ventricular aneurysmectomy for postischemic ventricular aneurysm, the findings of thallium 201 and metaiodobenzylguanidine myocardial scintigraphy were compared with direct immunohistochemical localization of the nerve fibers in the same area. This comparison showed good correspondence between scintigraphic and immunohistochemical data, although scintigraphy failed to detect areas of minimal sympathetic innervation. Moreover, microscopic analysis showed sympathetic nerve fibers with peculiar morphology and distribution in the aneurysmal zone.

CONCLUSION

There is a good correspondence between immunohistochemical and scintigraphic imaging in the detection of sympathetic cardiac nerves in human left ventricular aneurysms; a morphologically abnormal sympathetic reinnervation can be found in the aneurysmal area (although denervation can persist in some zones).

Toward a new blood vessel

Strategies to treat atherosclerotic coronary artery disease include coronary artery bypass grafting (CABG), in which grafts are used to bypass atherosclerotic vessels and restore blood flow to the ischemic myocardium. The grafts used include healthy arteries or veins harvested from a separate site. Results with arterial grafts have been superior to venous grafts; promoting the practice of total arterial revascularization using only arterial grafts. Suitable arterial grafts, however, are scarce and harvest procedures add to morbidity and cost. Tissue engineering combines the principles of engineering with life sciences for the development of biological substitutes and restore, maintain or improve tissue function. Advances in this field have included the development of tissue-engineered blood vessels, with the potential to serve as arterial grafts, conduits or fistulae. This review describes the history of tissue engineering arteries, the techniques used, and progress to date. The source of cells and the future direction of this field are explored.

Endovascular irradiation impairs vascular functional responses in noninjured pig coronary arteries

PURPOSE

To assess the effects of endovascular irradiation on vascular structure and function in pig coronary arteries in the absence of vascular injury.

METHODS AND MATERIALS

Vasomotor responses to contractions of KCl and prostaglandin F2alpha (PGF2alpha), relaxations to endothelium-dependent (substance P, A23187) and -independent (sodium nitroprusside, SNP) agents; endothelial morphology and superoxide anion (02*-) production were investigated in control (naive), sham and irradiated (20 Gy, 32P) arteries 1 month after irradiation.

RESULTS

Contractions to KCl and PGF2alpha in the presence of L-NAME were significantly decreased, relaxations to substance P and A23187 were abolished and SNP-induced relaxation was potentiated in irradiated arteries compared to naive and sham-treated vessels. Scanning electron microscopy (SEM) revealed enlarged endothelial cells (ECs) exhibiting surface microvilli. O2*- production was significantly increased in irradiated vessels (437.0 +/- 37.3 vs. 126.0 +/- 11.6 RLU/s/mg tissue, P < .01).

CONCLUSIONS

One month after brachytherapy, normal pig coronary arteries showed abnormal vascular reactivity, altered endothelial morphology and increased production of O2*-. Lack of relaxation to substance P and A23187 reflects ionizing radiation-mediated damage to ECs, whereas potentiation of relaxation to SNP suggests additional deleterious effects on medial smooth muscle cells (SMCs). Increased O2*- production might have contributed to endothelial dysfunction by scavenging nitric oxide (NO).

[Regulation and dysfunction of endothelium-dependent vasomotricity. What can be applied to clinical practice?]

FUNCTIONS OF THE ENDOTHELIUM: The endothelium plays a pivotal role in regulating vasomotor tone, vessel permeability, blood cell extravasation, and antiatherogenic, antithrombogenic and antiadhesive processes.

DYSFUNCTION OF THE ENDOTHELIUM

Demonstrated, in particular, by endothelium-dependent vasomotricity disorders, endothelium dysfunction occurs in many psysiological and pathological situations that lead to atherosclerosis: advanced age, menopause, high blood pressure, dyslipidemia, diabetes, smoking, elevated homocysteinemia, chronic renal failure.... These dysfunctions of the endothelium constitute the fundamental and very early step in the development of atherosclerosis.

PREVENTION

Specific treatment of functional anomalies of the endothelium can be an essential element in the prevention of atherosclerosis. In certain cases, he cause of endothelial dysfunction may be related to the presence of radical oxygen species, nitric oxide inhibitors, or increased synthesis or release of endothelin. Potential treatments should be adapted to the specific cause of the underlying endothelial anomaly: antioxidants, statins, anti-endothelins, or converting enzyme inhibitors. In clinical practice, it may be important to recognize the cause of endothelial dysfunction for adapted early drug therapy.

Intestinal ischemia and reperfusion impairs vasomotor functions of pulmonary vascular bed

OBJECTIVE

To investigate the effects of intestinal ischemia and reperfusion (I/R) on the pulmonary vascular endothelium and smooth muscle.

SUMMARY BACKGROUND DATA

Respiratory failure is an important cause of death and complications after intestinal I/R. Although the mechanism of respiratory failure in this setting is complex and poorly understood, recent studies of lung injury suggest that endothelial dysfunction may play a significant role.

METHODS

A rat model of acute lung injury was studied after 60 minutes of superior mesenteric arterial occlusion followed by either 120 or 240 minutes of reperfusion. The pulmonary vasomotor function was examined in isolated lungs perfused at a constant flow rate.

RESULTS

Sixty minutes of intestinal ischemia followed by 120 or 240 minutes of reperfusion led to a significant reduction in the ability of the pulmonary vasculature to respond to angiotensin II, acetylcholine, and calcium ionophore but not to nitroglycerin. The vasoconstriction response to N(G)-nitro-L-arginine methyl ester, which is a measure of basal nitric oxide release, was diminished in the 240-minute reperfusion group. Intestinal I/R was also associated with pulmonary leukosequestration and increased pulmonary microvascular leakage.

CONCLUSIONS

Basal and agonist-stimulated release of nitric oxide from the pulmonary vascular endothelium and the ability of pulmonary smooth muscle to contract in response to angiotensin II were impaired by intestinal I/R. Such functional impairment in both pulmonary vascular endothelium and smooth muscle may contribute to the alveolocapillary dysfunction and pulmonary hypertension found in acute lung injury after intestinal I/R.

Reflex sympathetic dystrophy in children

Reflex sympathetic dystrophy is a syndrome characterized by pain in one or more extremities, usually associated with vasomotor changes. Its occurrence in childhood has long been thought to be rare. We describe six cases of pediatric reflex sympathetic dystrophy and suggest that this syndrome could be underdiagnosed in children and adolescents. Psychologic problems frequently play a role in this disorder, which often can be treated conservatively. We also point out that the diagnosis is mainly clinical. An early diagnosis can avoid unnecessary tests and potentially can improve response to treatment, and prognosis.

Effects of chronic pulmonary overcirculation on pulmonary vasomotor tone

BACKGROUND

A model of shunt-induced pulmonary hypertension was used to study the effects of pulmonary overcirculation on endothelial nitric oxide synthase (eNOS) and cytochrome P450-4A (cP450-4A) vasodilatory mechanisms and related hemodynamic responses.

METHODS

An aortopulmonary shunt was constructed in 6-week-old piglets (n = 7, sham-operated controls n = 8). Hemodynamic measurements were made 4 weeks later under serial experimental conditions: baseline (fractional concentration of oxygen, 0.4); inhaled nitric oxide, 25 ppm (INO); hypoxia (fractional concentration of oxygen, 0.14); hypoxia + INO; N(omega)-nitro-L-arginine methylester (L-NAME 30 mg/kg intravenously, competitive NOS inhibitor); and L-NAME + INO. Lung protein levels of eNOS and cP450-4A and NOS activity were compared between groups.

RESULTS

Shunted animals had a higher baseline pulmonary artery pressure (p < 0.05). L-NAME resulted in a greater increase in pulmonary vascular resistance in shunted animals (150% +/- 26% shunt versus 69% +/- 14% control; p = 0.01). The INO administered during baseline conditions decreased pulmonary vascular resistance only in control animals (p < 0.05). Protein levels of eNOS and NOS activity were similar in both groups; however, cP450-4A protein levels were decreased in the shunted group (p = 0.02).

CONCLUSIONS

The NO production was preserved in shunted animals but they demonstrated greater vasodilatory dependence on NO, evidenced by an exaggerated increase in pulmonary vascular resistance after NOS inhibition. Loss of the cP450-4A vasodilatory system may be the driving force for NO dependency in the shunted pulmonary circulation.

[Pattern of distribution of constitutive isoforms of NO synthase in the normal prostate and obstructive prostatic hyperplasia]

Nitric oxide (NO) is suggested as an important mediator for the regulation of biological processes. In the present study we tried to determine histochemically and immunohistochemically the localization and distribution of the constitutive NO-synthase Isoforms (bNOS and eNOS) of 14 normal non-obstructive and 12 hyperplastic obstructive human prostates. Differentiated nitrinergic innervation was shown for the prostate glands, fibromuscular stroma and blood vessels by NADPH-diaphorase staining and immunohistochemically with specific NOS antibodies. In the specimens with benign prostatic hyperplasia nitrinergic innervation seems to be distinctly reduced. The vascular distribution of NOS provides evidence for segmental differentiation of NO-mediated vascular regulation. The NADPH-diaphorase reaction was not confirmed immunohistochemically by the specific NOS antibody in the glandular epithelium. The distribution of NO synthase shows the importance of nitric oxide in the regulation of smooth muscle tone, blood flow and secretory function in the normal and hyperplastic human prostate.

[Electron microscopy studies of vascular innervation of nasal mucosa in the human]

BACKGROUND

The distribution of neural structures in human nasal vasculature is still not completely understood. To date, immunocytochemical and histochemical studies of the innervation pattern and neurotransmitter distribution have only been performed using light microscopy. The aim of this study was to verify these results by electron microscopy and to obtain new knowledge of the innervation of the individual vessel types. The target was to determine the role of the different vessels in the swelling mechanism in human nasal mucosa.

MATERIAL AND METHODS

Specimens were prefixed in glutaraldehyde and postfixed in osmium tetroxide. After dehydration they were embedded in araldite. Ultrathin sections were cut, contrasted with uranylacetate and lead citrate, and studied under EM.

RESULTS

Nasal vasculature is controlled by a dense innervation. Amyelinated longitudinal nerve bundles and smaller axon conglomerates are detected in the arterial adventitia. Capacitance vessels (veins) in general show few nerve structures, which, in contrast to arteries, are also located between the smooth muscle cells. Cushion veins, however, reveal a stronger innervation pattern especially in their muscular swelling. In contrast to smaller arterioles, no axons can de demonstrated in capillaries.

CONCLUSION

The density of innervation in arteries and cushion veins seems to indicate that these vessel types are the central neural control point for the swelling mechanism in human nasal mucosa. Capillary function, however, does not seem to be directly influenced by the autonomic nervous system.

Clinical and radiologic findings in progressive facial hemiatrophy (Parry-Romberg syndrome)

We describe the clinical and radiologic changes related to progressive facial hemiatrophy (Parry-Romberg syndrome) occurring during a 20-month period in a child who presented with unilateral neurologic deficits and facial hemiatrophy. CT and MR findings included unilateral focal infarctions in the corpus callosum, diffuse deep and subcortical white matter signal changes, mild cortical thickening, and leptomeningeal enhancement with dense mineral deposition. Angiographic findings were normal. We hypothesize that a noninfectious, unilateral inflammatory process, possibly associated with a chronic vasomotor disturbance and sympathetic nerve chain inflammation, was a major factor in the pathogenesis of this syndrome.

Effect of steroid therapy on parameters of peripheral autonomic dysfunction in leprosy patients with acute neuritis

Recent electrophysiological studies on peripheral autonomic dysfunction in leprosy patients show a high prevalence of autonomic dysfunction as measured by abnormal vasomotor reflexes (VMR) and absent sympathetic skin response (SSR). Nothing is known about the reversibility of these autonomic parameters with treatment. Since there is evidence that small fiber function may be the most reversible component in neuropathies, we measured the effect of steroid treatment on autonomic parameters together with motor and sensory functions in leprosy patients with acute neuritis. Control subjects were investigated for repeatability testing of autonomic function. Due to a relatively high variability on repeat VMR testing in the controls, we defined a change in VMR testing as a change of > 30%. With this definition, the VMR of 14.8% of the patients improved, 75% remained unchanged, and 10.2% worsened. Absent SSR became positive in 16.6% and remained unchanged in 83.4%. Improvement in sensory motor functions was seen in 21.2% and 1.3% of the patients, respectively.

Optic nerve vasomotor effects of topical beta-adrenergic antagonists in rabbits

PURPOSE

To examine the anterior optic nerve vasomotor effects of nonselective and relatively beta-1-selective beta-adrenergic antagonists in rabbits, because different influences on optic nerve blood flow with these medications have been suggested.

METHODS

After topical therapy for 30 days with either timolol maleate 0.5% (six rabbits), betaxolol hydrochloride 0.5% (six rabbits), or placebo (two rabbits), the microvasculature of the optic nerve was examined with an intraluminal microvascular corrosion casting technique. The investigators were masked to both the medication group and the treated eye. The constriction, in percent of the downstream vessel caliber, was measured at the vascular branching point of arterioles supplying the anterior optic nerve. An average constriction was calculated and compared between the medication groups and between the treated and the contralateral, untreated eyes.

RESULTS

Constriction values from a total of 218 arterioles supplying the anterior optic nerve were obtained for the 14 rabbits. The means of the average constriction on the treated side were comparable between the groups treated with timolol maleate, betaxolol hydrochloride, and placebo (one-way analysis of variance, P = .64), as well as between the treated and untreated eyes (two-tailed t-test for paired variables, P = .68 for timolol maleate and P = .42 for betaxolol hydrochloride). The statistical power to find a difference of 5% or more average constriction was at least 90%.

CONCLUSIONS

Both relatively selective and nonselective beta-adrenergic antagonists produce no observable optic nerve vasomotor effects in the rabbit eye.

Enhanced sympathetic reactivity to glutamate stimulation in medulla oblongata of spontaneously hypertensive rats

The distribution and reactivity of vasomotor sites in the ventrolateral (VLM) and dorsomedial medulla (DMM) of stroke-prone spontaneously hypertensive rats (SHRSP), spontaneously hypertensive rats (SHR), and Wistar-Kyoto rats (WKY) were compared. Rats were anesthetized with alpha-chloralose and urethan. Baroreceptor denervation and vagotomy were performed. L-Glutamate (Glu, 10 mM, 30 nl) was microinjected into the DMM or VLM to identify vasoactive sites. The extent and the patterns of distribution of these sites in the three strains of rats were similar. The dose-response curve of the vasoactive site was studied with 1-500 pmol of Glu. The maximum responses of blood pressure and renal sympathetic activity were larger and threshold doses of Glu were lower in hypertensive rats. The significance of the differences among the strains was analyzed before and after adjustment for baseline pressure or activity. Most of the differences were statistically significant before baseline adjustment. After baseline adjustment, many differences between the SHRSP and the WKY remained significant. However, the only significant difference detected between the SHR and the WKY was the threshold dose for eliciting renal sympathetic change in the caudal VLM. These results suggest that there may be a general increase in excitability of the vasomotor neurons in the medulla of the hypertensive rats.

Perivascular neuropeptides (NPY, VIP, CGRP and SP) in human brain vessels after subarachnoid haemorrhage

INTRODUCTION--Cerebral blood vessels are innervated by sympathetic nerve fibres storing neuropeptide Y (NPY), parasympathetic nerves storing acetylcholine, vasoactive intestinal peptide (VIP) and sensory afferent fibres containing calcitonin gene-related peptide (CGRP), substance P (SP) and neurokinin A. In experimental studies on subarachnoid haemorrhage (SAH) there are indications that perivascular peptides are involved. In the present study we have in man measured the levels of NPY, VIP, SP and CGRP in brain vessels of patients that have suffered a fatal SAH and compared this with the levels encountered in subjects that died of an extracerebral cause. MATERIAL AND METHODS--Vessels from patients who have died from SAH or nonSAH were obtained during autopsy performed within 24 hrs after death. The peptides were extracted and fractionated with reversed phase liquid chromatography (HPLC). The levels of NPY, VIP, SP, and CGRP were measured with radioimmunoassay. Vasomotor responses of human cerebral arteries were performed using a sensitive in vitro system. RESULTS--Human cerebral vessels contained NPY, VIP, CGRP and SP which eluted at the same positions as the authentic peptides. The level of CGRP was significantly lower (p < 0.01) in arteries removed from SAH patients as compared to control subjects. The level of SP was not changed, if anything it tended to be increased after SAH. The levels of NPY and VIP were not significantly altered after SAH. In isolated brain vessels alpha-CGRP was a potent vasodilator of arteries precontracted with whole blood, prostaglandin F2 alpha or endothelin. It had a poor effect on vessels precontracted with 60 mM potassium. CONCLUSION--The evidence suggest that the trigemino-cerebrovascular system, storing CGRP and SP, is to a differential degree involved in the pathophysiology of SAH in man and supports the hypothesis of an exhaustion of CGRP as one important factor in the development of late spasm occurring after SAH.

Cerebral edema

Cerebral edema continues to plague clinicians caring for patients with acute catastrophic neurologic disease. The defect responsible for the accumulation of water in the brain appears to reflect loss of the strict permeability barrier of the cerebral vasculature. A greater understanding of the physiologic mechanisms at work in the blood-brain barrier have helped target therapies at the vascular interface between the circulating blood and the brain. The mounting evidence which implicates inflammatory events as causally related to the loss of cerebrovascular impermeability supports the clinical strategy of suppression of acute inflammation. Clearly, further advances in the management of cerebral edema will be strongly influenced by the development of specific anti-inflammatory pharmaceuticals.

Cardiac adrenergic innervation after instrumentation of the coronary artery in dog

A fine methacrylate ring (not constricting the artery) was placed around the ramus interventricularis anterior (RIA) of the left coronary artery in dogs. By means of Falck's histochemical technique an extensive degeneration of the vasomotor and cardiomotor adrenergic innervation of ventricles was detected 14 days after the procedure. The innervation of atria remained intact. The surgical intervention as well as the scarring process (which compressed the conducting parts of axons composing the perivascular nerves) induced the degeneration. The results have important implications for experiments with instrumented arteries.

Vasomotor factors in the Shwartzman phenomenon

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