Endothelin and Raynaud's phenomenon

Care of patients with scleroderma in the intensive care setting

Scleroderma or systemic sclerosis (SSc) is a connective tissue disease (CTD) associated with fibrosing and vascular complications involving multiple organs. The care of these patients in the critical care setting is frequently challenging due to multiple complications and refractory organ involvement. However, awareness of specific organ involvement associated with scleroderma can allow many complications to be anticipated and effectively treated. Cardiac involvement can lead to arrhythmias and heart failure, whereas pulmonary involvement can be associated with pulmonary arterial hypertension, fibrosis, or both. Renal vascular disease and scleroderma renal crisis (SRC), once a uniformly fatal complication, is particularly important to recognize early, as it can be treated successfully. Gastrointestinal involvement can lead to bleeding, aspiration, obstruction, and malabsorption. Severe Raynaud may lead to digital ischemia and gangrene. Therapies must target involved organ system or organ systems. Corticosteroids, a mainstay for related CTDs, do not typically provide any benefit and may cause harm. Vasodilators can effectively treat vascular complications but must target the appropriate vascular bed. Proactive utilization of proton pump inhibitors, recognition of bleeding from gastrointestinal vascular ectasia, and nutritional support can considerably ameliorate gastrointestinal morbidities. Effective treatment of fibrotic complications remains elusive and is the current frontier for scleroderma therapeutics.

Pulmonary hypertension associated with sarcoidosis

Pulmonary involvement is common in sarcoidosis, an immune-mediated inflammatory disorder that is characterized by non-caseating granulomas in tissue. Sarcoid patients with advanced pulmonary disease, especially end-stage pulmonary fibrosis, risk developing pulmonary hypertension (World Health Organization group III pulmonary hypertension secondary to hypoxic lung disease). Increased levels of endothelin (ET)-1 in plasma and bronchoalveolar lavage of some sarcoid patients suggest that ET-1 may be driving pulmonary fibrosis and sarcoidosis-associated pulmonary hypertension. Although a relationship between raised levels of ET-1 and clinical phenotype is yet to be identified, early evidence from studies of ET-1 blockade with drugs such as bosentan is encouraging. Such therapy possibly could be combined with standard anti-inflammatory agents to improve outcome.

Scale for chemotherapy-induced long-term neurotoxicity (SCIN): psychometrics, validation, and findings in a large sample of testicular cancer survivors

BACKGROUND

Neurotoxicity is common after modern chemotherapy, and can be assessed both objectively and subjectively based on symptoms reported by patients. The aim of this study was to explore the psychometric properties of a brief self-report scale for chemotherapy induced long-term neurotoxicity (the SCIN).

METHODS

As part of a questionnaire survey 684 testicular cancer survivors (TCSs) filled in the SCIN, which assesses peripheral sensory neuropathy (paresthesias), Raynaud's phenomenon, and ototoxicity. Factor structure and internal consistency reliability of the SCIN were tested by the split-half method. In 538 TCSs, audiogram data were compared to the patients SCIN ratings of hearing.

RESULTS

The internal consistency of the SCIN showed a Cronbach's alpha of 0.72. The three-factor structure of the SCIN was confirmed with 77% explained variance. All the SCIN items discriminated significantly between the TCSs who had been treated with cisplatin-based chemotherapy vs. those who did not receive such treatment. The individual cumulative cisplatin dose correlated significantly with all the SCIN items. The Pearson product-moment correlation coefficient was 0.54 between hearing reduction at 4000 Hertz measured by audiogram and the SCIN self-report of reduced hearing.

CONCLUSION

The SCIN shows good psychometric properties, and is recommended as a brief screening instrument for chemotheraphy-indeed neurotoxicity.

Vascular Toxicity of Antineoplastic Agents

Among the various deleterious effects of cancer chemotherapy, vascular toxicity is the least well recognized. This lack of recognition may be because the vasculotoxic phenomena are not unique to antineoplastic agents, can occur in patients without exposure to these agents, and the fact cancer itself may produce a hypercoagulable state. As a result, many vascular events either go unnoticed, are ignored, and/or are attributed to the underlying malignancy. Many antineoplastic therapies are associated with various vascular phenomena that range from simple phelibitis to lethal microangiopathy. Recognition of these events is important to minimize the morbidity and even prevent unnecessary deaths. Herein we review the vascular syndromes that have been reported in association with antineoplastic agents.

Digital vascular responses and serum endothelin-1 concentrations in primary and secondary Raynaud's phenomenon

OBJECTIVE

To determine circulating endothelin-1 levels (ET-1) in patients with primary or secondary associated Raynaud's phenomenon (RP) under resting conditions and in response to cold provocation.

METHODS

Patients were categorised as primary RP (18) or scleroderma associated RP (14). Finger blood flow was measured by venous occlusion plethysmography at finger temperatures of 32 degrees C and 24 degrees C. Vasospasm was detected as a finger systolic pressure of 0 mm Hg after standardised provocative cooling. Severity of vasospasm was assessed by the level of cooling required to provoke spasm. Plasma ET-1 levels were measured in antecubital blood withdrawn under baseline conditions (finger 32 degrees C) and at the point of vasospasm. Measurements were also made in 19 matched control subjects.

RESULTS

Finger blood flow was lower in patients with RP than in controls, with no difference between the two RP groups. Vasospasm occurred in all patients with RP but not in any control subjects and a grading system of severity was established. Baseline plasma ET-1 levels were similar in patients with RP and controls. Increases in ET-1 levels at the point of vasospasm in patients or corresponding timepoint in controls were also similar. There was no significant difference between the ET-1 levels in the two RP subgroups when the fingers were warm or when vasospasm was present.

CONCLUSIONS

These results do not support the hypothesis that ET-1 plays a part in the pathogenesis of RP. Objective testing is a useful adjunct to the clinical diagnosis of RP and allows assignment of a severity grade.

Objective and subjective effects of treatment for testicular cancer on sexual function

OBJECTIVE

To determine whether the treatment of patients with testicular cancer, using cisplatin combined with etoposide and bleomycin (BEP) after orchidectomy in those with disseminated disease, causes changes in sex hormones and penile vascularization, possibly related to sexual dysfunction.

PATIENTS AND METHODS

Ten patients treated with BEP were compared with 11 undergoing orchidectomy alone followed by surveillance. Sex hormone levels were analysed and cavernosal artery duplex ultrasonography performed before orchidectomy and at 6 and 12 months afterward. Patients were questioned about their sexual function. After 1 year, a visual erotic stimulation (VES) test was performed to assess penile rigidity.

RESULTS

In contrast to the surveillance group, BEP-treated patients had higher follicle-stimulating hormone (4.6 vs 26.5 U/L) and luteinizing hormone (1.4 vs 8.2 U/L) levels, and lower testosterone levels (21.1 vs 14.7 nmol/L) at 6 months than at baseline. At 1 year, most patients had compensated hypergonadotrophic eugonadism, but Leydig cell function had recovered. Changes in cavernosal artery peak flow velocities induced by local injection with papaverine/phentolamine showed no difference between the groups before and 6 months after orchidectomy. Loss of libido and erectile dysfunction were reported more frequently by BEP-treated patients. However, 1 year after treatment, most reported a satisfying sex life and VES resulted in a rigid erection in nearly all patients. The reported erectile dysfunction could not be explained by changes in plasma testosterone levels or diminished blood flow velocities.

CONCLUSIONS

After being diagnosed with testicular cancer, sexual morbidity is considerable, but within 1 year some improvement may be expected. BEP induces transient testicular dysfunction but this recovers. Although BEP is related to symptoms of angiopathy, cavernosal blood flow seems to be unaffected. These findings and the normal VES-evoked penile rigidity suggest that sexual dysfunction is more psychological than organically induced by BEP.

[Endothelin-1 and cardiovascular diseases]

INTRODUCTION

Endothelins are peptides released from endothelial cells. According to both their structure and receptor affinity, three isoforms may be identified. Endothelin-1 is secreted abluminally by endothelial cells, and binds ETA and ETB2 receptors expressed on vascular smooth muscle cells, and ETB1 expressed on endothelial cells. ETA and ETB2 receptors stimulation induces smooth muscle contraction and proliferation, whereas ETB1 receptors stimulation induces relaxation.

CURRENT KNOWLEDGE AND KEY POINTS

Endothelin-1 plays an important role in maintaining peripheral vascular tone and systemic blood pressure. It is recognized to have a role in various diseases associated with vasoconstriction and vascular hypertrophy.

FUTURE PROSPECTS AND PROJECTS

Recent development of endothelin receptor antagonists seems promising for the treatment of heart failure and systemic hypertension, with interesting results obtained from short-term clinical trials. However, better evaluation of these drugs requires further long-term studies regarding not only the above mentioned diseases but also ischemic heart disease or pulmonary hypertension. Endothelin antagonists are therefore new therapeutic agents able to inhibit a vasoconstricting system that has been recently discovered. Results of ongoing clinical studies are awaited with interest.

Raynaud’s Phenomenon and Vascular Disease in Systemic Sclerosis

Raynaud's phenomenon (RP) is very often the first manifestation of SSc preceding the onset of all the other signs and symptoms of the disease. Two structures are involved in the pathogenesis of RP: the endothelium and the peripheral nervous system (PNS). The hypothesis is that SSc modifies consistently the activity of both these systems leading eventually to RP. The disease, through the injury to the endothelium, jeopardizes the basilar endothelial-dependent vascular tone control. An increase of endothelin, a potent endothelial-derived vasoconstrictor, and the reduction of nitric oxide, one of the main endothelial vasodilators, are two key events involved in the genesis of RP. The PNS is also targeted by the disease as demonstrated by the high incidence of neuropathy in SSc patients. A marked reduction of sensory fibres has been detected in SSc skin. Thus, the involvement of nerve terminals reduces the vasodilatory, endothelial dependent or independent, potential of the neuropeptides released by sensory nerve endings. Indeed, an increased sensitivity of alpha 2 adrenoceptors mediated vasoconstriction has been shown in SSc skin. The complex vasodilatory network formed by the interaction between the endothelium and the PNS seems greatly damaged by SSc leading inesorably toward vascular tone dysfunction clinically evident as RP.

Whole-body cooling increases plasma endothelin-1 levels in women with primary Raynaud's phenomenon

To understand better the role of endothelin-1 (ET-1) in the pathogenesis of primary Raynaud's phenomenon (PRP), we investigated the basal ET-1 plasma levels and changes after whole-body cooling in healthy women and those with PRP. The study was performed as an open parallel-group comparison during the month of February. The Raynaud group included 21 female patients (mean age 45.3 years, range 21-57 years) who had had disabling Raynaud's phenomenon for a mean period of 17 years (range 2-26 years). The control group consisted of 25 healthy women (mean age 43.6 years, range 27-56 years). Plasma levels of ET-1 were measured on two separate occasions: once after 30 min of rest at room temperature and after 40 min of whole-body cooling. There were no significant differences in baseline plasma ET-1 levels between the two groups of women. The plasma ET-1 levels increased significantly in the PRP group after cold exposure (mean difference 0.11 pmol l-1, 95% CI 0.005-0.214, P = 0.012). In contrast, the levels of plasma ET-1 in the control group did not change significantly after cold provocation. In conclusion, no differences in plasma basal levels of ET-1 were observed between the two groups. However, women suffering from Raynaud's phenomenon responded with a slight but significant elevation in plasma levels of ET-1 after whole-body cooling, whereas the healthy control subjects did not. The results from the present study confirm previous observations that endothelial dysfunction may be of aetiological importance in PRP.

Role of endothelin receptors, calcium and nitric oxide in the potentiation by endothelin-1 of the sympathetic contraction of rabbit ear artery during cooling

1. To examine further the potentiation by endothelin-1 on the vascular response to sympathetic stimulation, we studied the isometric response of isolated segments, 2 mm long, from the rabbit central ear artery to electrical field stimulation (1-8 Hz), under different conditions, at 37 degrees C and during cooling (30 degrees C). 2. Electrical stimulation produced frequency-dependent contraction, which was reduced (about 63% for 8 Hz) during cooling. At 30 degrees C, but not at 37 degrees C, endothelin-1 (1, 3 and 10 nM) potentiated the contraction to electrical stimulation in a dose-dependent way (from 43 +/- 7% to 190 +/- 25% for 8 Hz). 3. This potentiation by endothelin-1 was reduced by the antagonist for endothelin ETA receptors BQ-123 (10 microM) but not by the antagonist for endothelin ETB receptors BQ-788 (10 microM). The agonist for endothelin ETB receptors IRL-1620 (0.1 microM) did not modify the contraction to electrical stimulation. 4. The blocker of L-type Ca2+ channels verapamil (10 microM l-1) reduced (about 72% for 8 Hz) and the unspecific blocker of Ca(2+)-channels NiCl2 (1 mM) practically abolished (about 98%), the potentiating effects of endothelin-1 found at 30 degrees C. 5. Inhibition of nitric oxide synthesis with NG-nitro-L-arginine (L-NOARG, 0.1 mM) increased the contraction to electrical stimulation at 30 degrees C more than at 37 degrees C (for 8 Hz, this increment was 297 +/- 118% at 30 degrees C, and 66 +/- 15% at 37 degrees C). Endothelium removal increased the contraction to electrical stimulation at 30 degrees C (about 91% for 8 Hz) but not at 37 degrees C. Both L-NOARG and endothelium removal abolished the potentiating effects of endothelin-1 on the response to electrical stimulation found at 30 degrees C. 6. These results in the rabbit ear artery suggest that during cooling, endothelin-1 potentiates the contraction to sympathetic stimulation, which could be mediated at least in part by increasing Ca2+ entry after activation of endothelin ETA receptors. This potentiating effect of endothelin-1 may require the presence of an inhibitory tone due to endothelial nitric oxide.

Plasma endothelin-1 levels in Behçet's disease

Plasma concentrations of endothelin-1 (ET-1), a vasoconstrictor peptide released from vascular endothelial and synovial cells, were measured by radioimmunoassay in 27 patients with Behçet's disease (BD) and 18 healthy controls. The plasma ET-1 concentrations were found to be significantly increased in patients with BD (121.15 +/- 11.6 fmol/dl) compared with the healthy subjects (89.37 +/- 8.03 fmol/dl p < 0.05). The elevation of ET-1 did not correlate with the disease duration, gender, ocular or articular involvement. Whether the elevated ET-1 level is a direct result of its increased synthesis from injured vascular endothelial cells or whether its presence in high concentrations may be responsible, together with other factors for both vascular and articular complications in patients with BD is uncertain.

Pathophysiological significance of plasma endothelin in peripheral circulatory disturbances

Endothelin (ET) is produced in blood vessels and is a novel potent vasoconstrictor. Although the presence of immunoreactive ET in the circulating blood suggests that ET plays an important role in the regulation of systemic and/or local hemodynamics, the role of circulating ET has not been ascertained using human populations. We examined the values of the ET level and peripheral blood flow, including other biochemical and physiological factors, in 108 healthy adults who participated in annual health examinations of Japanese adults living in a rural community in 1992 and 1993. A small change in ET after the passage of one year showed good reproducibility of the value. ET was positively correlated with diastolic blood pressure (BP) and negatively with finger skin blood flow in healthy adults. Multiple regression analysis demonstreted that the positive relationship between ET and diastolic BP was independent of other health indicators. A detailed examination using optical spectroscopy for elderly institutionalized subjects without any trouble in the activity of daily living revealed a negative correlation of ET with saturated oxygen in blood, tissue hemoglobin volume and local blood flow and a positive one with the local oxygen extraction fraction. The present study indicated that increased ET in the elderly subjects was associated with hypoxia not only in the local finger skin region, but also possibly in the arterial tissue, suggesting that ET is involved in atherosclerosis. The negative correlation between ET and finger skin blood flow seen in the healthy adults may be induced by hypoxia. Although we recognized a positive correlation between ET and BP, the increase in ET seemed to be an outcome of elevation in BP rather than a cause of hypertension.

Serum endothelin concentrations in workers exposed to vibration

OBJECTIVES

Endothelin 1 (ET1) is one of a newly discovered family of potent naturally occurring vasoconstrictors produced by the endothelium. A few publications indicated that the peptide may have a role in idiopathic Raynaud's phenomenon and Raynaud's phenomenon secondary to connective tissue disease. The aim of this study was to compare serum endothelin concentrations in people with vibration induced white finger (VWF) with those of controls exposed to vibration, and unexposed (pure) controls.

SUBJECTS AND METHODS

Male volunteers from a stonemasonry, two quarries, and an insurance company were classified by questionnaire and clinical examination into men with VWF (cases, n = 31), exposed controls (n = 22), or pure controls (n = 36). All subjects were asked to provide two venous blood specimens: a baseline sample after a period of warm equilibration (30 minutes seated in a warm room and 20 minutes with both hands immersed in a water bath at 37 degrees C); and again after cold challenge (both hands immersed in a water bath at 6 degrees C for six minutes). Serum concentrations of the 21 amino acid peptide endothelin ET1-21 were measured by radioimmunoassay.

RESULTS

Baseline concentrations of ET1-21 were found to be lower in cases (mean = 12.2 pmol/l) than in the two control groups (mean = 14.7 pmol/l in exposed controls; mean = 14.3 pmol/l in pure controls). Among cases there was a broad inverse relation between severity, as measured by the Griffin blanching score, and baseline ET1-21 (Spearman rank correlation coefficient -0.58, P < 0.001). Cold challenge provoked an overall rise in ET1-21 in all groups, but larger and significant mean absolute and percentage rises were found in cases (4.1 pmol/l and 54%) than in the control groups (2.6 pmol/l and 21% in exposed controls; 1.5 pmol/l and 20% in pure controls). Similar but more obvious differences occurred when controls were compared with those cases who gave a more severe history of disease (Griffin blanching score > or = 24) and those cases found to blanch after cold challenge. In these case subsets baseline ET1-21 was nearly 50% lower than for controls and a four and a half to fivefold greater percentage rise in ET1-21 occurred upon cold challenge. Differences were significant. Close matching for age and smoking did not alter the principal findings. No significant differences, whether in baseline or cold response, were found between unexposed and exposed controls.

CONCLUSIONS

Baseline findings seem to contradict various published series and attempts are made to reconcile the differences. It is suggested that a lower baseline ET1-21 in cases may result from a disease compensation mechanism or damage effect. The large relative rise in serum ET1-21 when cases are cold challenged may contribute directly or indirectly to vasospasm, but a simple mechanism is unlikely and interpretation is limited by the absence of measurements of forearm blood flow.

Change in digital blood flow with simultaneous reduction in plasma endothelin induced by hand-arm vibration

Involvement of endothelium-derived relaxing factor (EDRF) or endothelium-derived constricting factor (EDCF) has been proposed as the pathophysiologic mechanism of vibration-induced white finger (VWF). Recent evidence that endothelin is a potent vasoconstrictor peptide indicates that it may play a role in vasoregulation during vibration exposure through the local actions of EDRF or EDCF. Therefore, we examined the effects of grasping (50 N) and hand-arm vibration (50 m/s2 rms, 120 Hz, x-axis) on digital blood flow (DBF) and on the level of plasma endothelin in seven healthy male office workers. Grasping decreased DBF without affecting endothelin, and vibration increased DBF with a simultaneous reduction in endothelin. The grasping-induced decrease in DBF seemed to be due to mechanical compression of the vessels. The negative correlation between DBF and endothelin during vibration exposure suggests that a reduction in release of endothelin from smooth muscle into the vessel cavity during vibration leads to vasodilatation, possibly attributable to the local axon reflex.

Elevated plasma endothelin levels in systemic sclerosis

Endothelin is a novel potent vasoconstrictor peptide produced mainly by endothelial cells. Thrombomodulin is a high-affinity thrombin receptor on vascular endothelial cells that plays an important role as a natural anticoagulant. In this study, we measured plasma levels of endothelin and thrombomodulin in patients with systemic sclerosis or Raynaud's disease. Plasma levels of endothelin and the ratio of thrombomodulin to creatinine were significantly increased in patients with systemic sclerosis compared with normal controls, and there was a positive correlation between these two indicators (r = 0.615, P = 0.004). Moreover, plasma levels of endothelin were significantly higher in patients with diffuse systemic sclerosis than in patients with limited systemic sclerosis. In contrast, plasma levels of endothelin in patients with Raynaud's disease were not significantly increased. These results suggest that increased plasma levels of endothelin and thrombomodulin may reflect microvascular damage in systemic sclerosis.

Characterization of endothelin-binding sites in human skin and their regulation in primary Raynaud's phenomenon and systemic sclerosis

Endothelin (ET), which mediates vasoconstrictor and vasodilator activities via multiple receptor subtypes, has been implicated in the control of blood flow and vascular tone in human skin, and possibly in the abnormal vasoconstrictor response in primary Raynaud's phenomenon and systemic sclerosis. Using in vitro autoradiography we have examined the endothelin-binding characteristics and receptor subtypes of human skin, and sought to provide evidence for endothelin receptor regulation in skin from patients with primary or secondary Raynaud's phenomenon. Specific 125I-ET-1 and 125I-ET-3 binding sites were localized to microvessels of the sub-epidermal plexus and dermal papillae, larger blood vessels, sweat glands, epidermis, and hair follicles. Both ETA and ETB receptors were demonstrated in microvessels and other structures. ET receptor heterogeneity in skin vasculature suggests a role for ET as an autocrine/paracrine regulator of vasoconstrictor and vasodilator pathways in human skin. The presence of binding sites in epidermis and hair follicles suggests a possible mitogenic function for endothelin in human skin. Endothelin-binding density was significantly higher (p < 0.05) in microvessels of skin from patients with systemic sclerosis but not significantly different in Raynaud's phenomenon patients, compared to controls. Lack of down regulation of ET receptors in Raynaud's phenomenon and systemic sclerosis may contribute to the pathogenesis of vasospasm in these diseases.