Time course of inflammatory response after renal artery stenting in patients with atherosclerotic renal stenosis

Endothelialization strategy of implant materials surface: The newest research in recent 5 years

In recent years, more and more metal or non-metal materials have been used in the treatment of cardiovascular diseases, but the vascular complications after transplantation are still the main factors restricting the clinical application of most grafts, such as acute thrombosis and graft restenosis. Implant materials have been extensively designed and surface optimized by researchers, but it is still too difficult to avoid complications. Natural vascular endodermis has excellent function, anti-coagulant and anti-intimal hyperplasia, and it is also the key to maintaining the homeostasis of normal vascular microenvironment. Therefore, how to promote the adhesion of endothelial cells (ECs) on the surface of cardiovascular materials to achieve endothelialization of the surface is the key to overcoming the complications after implant materialization. At present, the surface endothelialization design of materials based on materials surface science, bioactive molecules, and biological function intervention and feedback has attracted much attention. In this review, we summarize the related research on the surface modification of materials by endothelialization in recent years, and analyze the advantages and challenges of current endothelialization design ideas, explain the relationship between materials, cells, and vascular remodeling in order to find a more ideal endothelialization surface modification strategy for future researchers to meet the requirements of clinical biocompatibility of cardiovascular materials.

Relationship between Lp-PLA2 and in-stent restenosis after coronary stenting: a 3-year follow-up study

BACKGROUND AND AIMS

Coronary in-stent restenosis (ISR) is an important complication of percutaneous coronary intervention (PCI). However, the relationship between lipoprotein associated phospholipase A2 (Lp-PLA2) level and ISR after PCI is rarely reported. This study aims to explore the relationship between Lp-PLA2 and the occurrence of ISR at post-PCI and its predictive value for ISR.

METHODS AND RESULTS

Plasma Lp-PLA2 mass were measured in 847 patients planting 1262 stents and evaluated along with known risk indicators. One-year angiographic follow-up showed that baseline elevated Lp-PLA2 mass was strongly associated with early restenosis (95% CI = 1.062-3.050, P < 0.05). Beyond the first year, the occurrence of late restenosis (95% CI = 1.043-3.214, P < 0.05) was significantly larger in the elevated Lp-PLA2 group. Kaplan-Meier analysis after three-year clinical follow up suggested that Lp-PLA2 mass did add the positive effect on the occurrence of major adverse cardiovascular events (MACEs).

CONCLUSION

In conclusion, increased baseline plasma Lp-PLA2 predicts increased risks of re-stenosis and MACEs, which may be a novel biomarker for predicting ISR and MACEs.

Hyaluronic Acid Nanoparticle Composite Films Confer Favorable Time-Dependent Biofunctions for Vascular Wound Healing

Vascular stent implantation is the primary treatment for coronary artery disease. Surface modification of coronary stents is a topic of interest to prevent thrombosis and restenosis and to promote endothelization. However, bioactive coatings on implants have not yet been fully developed for the time-ordered biological requirements of vascular stents. The first month after vascular stent implantation, the pathological changes in the injured vascular tissue are complex and time-ordered. Therefore, vascular stents possess time-dependent biofunctions with early phase anticoagulant and anti-inflammatory properties. In the later stage, inhibitory effects on smooth muscle cell proliferation and the promotion of endothelial cell adhesion might meet the requirements of vascular repair. We fabricated three types of hyaluronic acid nanoparticles (HA-NPs) by subjecting HA and poly(ether imide) to ethyl(dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide coupling reaction. The HA-NPs prepared by HA with a molecular weight of 100 kDa showed the best stability in a hyaluronidase environment. HA-NP composite films (HA-NCFs) were then fabricated by coimmobilizing selected HA-NPs (100 kDa) and HA molecules (100 kDa) through amide reaction on PDA/HD coated 316 L stainless steel surfaces. The detachment behavior of HA-NPs (100 kDa) in PBS for 20 days indicated that the HA-NPs (100 kDa) gradually detached from the surface. In vitro tests (anticoagulant and anti-inflammatory tests, endothelial cells, and smooth muscle cells seeding, and bacterial adhesion test) indicated that the newly fabricated HA-NCFs have inhibitory effects on the adhesion of fibrinogen, platelets, macrophages, bacteria, SMCs, and ECs. As the HA-NPs detached from the surface, the HA-NCFs showed excellent gradual comprehensive biocompatibility, which promoted adhesion and proliferation of ECs while still exerting inhibitory effects on the platelets, macrophages, and SMCs. Finally, in vivo SS wire implantation test (aortic implantation in healthy Sprague-Dawley rats) showed that HA-NCFs possessed anti-inflammatory properties, inhibited the proliferation of smooth muscle cells, and promoted re-endothelialization. In particular, HA-NCFs with time-dependent biofunctions showed better antirestenosis effects than those of surfaces modified with molecular HA, which exhibited constant biocompatibility. This study provides an important basis for the construction of HA-NP composite films with favorable time-dependent biofunctions for the time-ordered biological requirements of vascular stent.

Changes in Cytokines, Sensory Tests, and Self-reported Pain Levels After Manual Treatment of Low Back Pain

STUDY DESIGN

Unbalanced 3-factor design with repeated measures on 1 factor.

OBJECTIVE

To determine the effect of manual treatment (MT) on cytokine and pain sensations in those with and without low back pain (LBP).

SUMMARY OF BACKGROUND DATA

Evidence suggests that MT reduces LBP but by unknown mechanisms. Certain cytokines have been elevated in patients with LBP and may be affected by MT.

METHODS

Participants aged 20-60 years with chronic LBP or without LBP were recruited and randomly assigned to MT, sham ultrasound treatment, or no treatment groups. Venous blood samples were collected and pain levels assessed at baseline, 1 hour later, and 24 hours later. Blood was analyzed for interleukin (IL)-1β, IL-6, tumor necrosis factor-α, and C-reactive protein. Pain levels were measured by pressure pain threshold (PPT), mechanical detection threshold (MDT), dynamic mechanical allodynia, and self-report.

RESULTS

Forty (30 women, age 36±11 y) participants completed the study, 33 with LBP (13 MT, 13 sham ultrasound treatment, and 7 no treatment) and 7 without LBP. Participants with or without LBP could not be differentiated on the basis of serum cytokine levels, PPT, or MDT (P≥0.08). There were no significant differences between the groups at 1 hour or 24 hours on serum cytokines, PPT, or MDT (P≥0.07). There was a significant decrease from baseline in IL-6 for the no treatment (LBP) group (P=0.04), in C-reactive protein for the sham ultrasound treatment group (P=0.03), in MDT for all 3 LBP groups (P≤0.02), and in self-reported pain for the MT and sham ultrasound treatment groups (P=0.03 and 0.01).

CONCLUSIONS

Self-reported pain was reduced with MT and sham ultrasound treatment 24 hours after treatment, but inflammatory markers within venous circulation and quantitative sensory tests were unable to differentiate between study groups. Therefore, we were unable to characterize mechanisms underlying chronic LBP.

Surface modification with dopamine and heparin/poly-L-lysine nanoparticles provides a favorable release behavior for the healing of vascular stent lesions

Surface biofunctional modification of coronary artery stents to prevent thrombosis and restenosis formation, as well as accelerate endothelialization, has become a new hot spot. However, bioactive coatings on implants are not yet sufficiently developed for long-term activity, as they quickly lose efficiency in vivo and finally fail. On the basis of a novel time-ordered concept of biofunctionality for vascular stents, heparin/poly l-lysine nanoparticle (NP) was developed and immobilized on a polydopamine-coated titanium surface, with the aim of regulating and maintaining the intravascular biological response within the normal range after biomaterial implantation. An in vitro dynamic release model was established to mimic the blood flow condition in vivo with three phases: (1) An early phase (1-7 days) with release of predominantly anticoagulant and anti-inflammatory substances and to a minor degree antiproliferative effects against smooth muscle cells (SMCs); (2) this is followed by a phase (7-14 days) of supported endothelial cell (ECs) proliferation and suppressed SMC proliferation with persisting high antithrombogenicity and anti-inflammatory properties of the surface. (3) Finally, a stable stage (14-28 days) with adequate biomolecules on the surface that maintain hemocompatibility and anti inflammation as well as inhibit SMCs proliferation and promote ECs growth. In vivo animal tests further confirmed that the NP-modified surface provides a favorable release behavior to apply a stage-adjusted remedy. We suggested that these observations provide important guidance and potential means for reasonable and suitable platform construction on a stent surface.

A meta-analysis of the utility of C-reactive protein in predicting early, intermediate-term and long term mortality and major adverse cardiac events in vascular surgical patients

We conducted a meta-analysis of the utility of pre-operative C reactive protein (CRP) in predicting early (< 30 days), intermediate (30-180 days) and long term (> 180 days) mortality and major adverse cardiac events (MACE; cardiac mortality and nonfatal myocardial infarction (MI) combined) following vascular surgery. Of 291 studies identified, ten prospective patient cohorts were identified. A pre-operative CRP > 3 mg x l(-1) was not associated with 30-day all-cause mortality, cardiac mortality, nonfatal myocardial infarction or MACE. Intermediate-term all-cause mortality, cardiac death and MACE showed a trend to a worse outcome (odds ratio (OR) 9.07, 95% confidence interval (CI) 0.86-96.28, p = 0.07; OR 8.71, 95% CI 0.5-153.1, p = 0.14 and OR 2.81, 95% CI 0.78-5.18, p = 0.15 respectively). Long term all cause mortality (OR 2.40, 95% CI 1.15-5.02, p = 0.02), cardiac death (OR 5.66, 95% CI 1.71-18.73, p = 0.005) and MACE (OR 2.76, 95% CI 1.38-5.55, p = 0.004) were significantly increased.

Systemic inflammatory response to renal artery percutaneous angioplasty with stent placement and the risk for restenosis: a pilot study

PURPOSE

Time changes in plasma concentrations of six different cytokines were investigated to evaluate the inflammatory response to renal artery stent placement.

MATERIALS AND METHODS

A total of 22 patients (17 men; mean age, 66 years +/- 13) with ostial renal artery stenosis and poorly controlled hypertension treated with stent placement were studied. Blood samples were collected at baseline and at 24 hours and 6 months after the intervention. Plasma concentrations of (i) tumor necrosis factor-alpha, (ii) interleukin-6 (IL-6), (iii) monocyte chemoattractant protein-1, (iv) intercellular adhesion molecule-1, (v) vascular cell adhesion molecule-1, and (vi) regulated upon activatin normal T-cell expressed presumed secreted were measured. Restenosis diagnosed with imaging follow-up at 6 months was recorded. Plasma concentrations of the aforementioned cytokines were compared between patients with and without restenosis.

RESULTS

IL-6 concentration increased significantly 24 hours after stent placement (8.3 pg/mL +/- 1.24 vs. 2.76 pg/mL +/- 1.27 at baseline) and returned to baseline levels (2.6 pg/mL +/- 1.77) at 6-month follow-up (P < .0001). No significant changes occurred in the concentrations of any other cytokines at the three time points. Baseline and 6-month concentrations of IL-6 were significantly higher in patients with restenosis than in those without restenosis (8.13 pg/mL +/- 4 vs 0.75 pg/mL +/- 0.47 [P < .005] and 9.55 pg/mL +/- 6.5 vs 0.42 pg/mL +/- 0.35 [P < .02], respectively).

CONCLUSIONS

Renal artery angioplasty with stent placement induces an inflammatory response, as evidenced by increased IL-6 production. Additionally, IL-6 seems to identify patients prone to develop restenosis; therefore, it might be used as an early predictor of restenosis after renal angioplasty with stent placement. However, larger studies are required to confirm IL-6 as a potential predictor of restenosis.

Comparison of changes in early inflammatory markers between sirolimus- and paclitaxel-eluting stent implantation

BACKGROUND

Systemic inflammation after coronary intervention identifies patients at increased risk of subsequent cardiac events. Cardiac events, especially in-stent restenosis, are less frequent after use of sirolimus-eluting stent (SES) compared with paclitaxel-eluting stent (PES). However, the underlying mechanism for this disparity is not well investigated. We hypothesize that an attenuated inflammatory response after SES implantation may be a contributor.

PURPOSE

In the present study, we sought to determine the early inflammatory response after SES implantation in patients with single-vessel disease compared with PES implantation, and evaluate the relationship between inflammatory response and late clinical outcomes in a randomized design.

METHODS

Thirty-two patients with stable angina were randomly enrolled into the two groups, SES or PSE group (n = 16 respectively). Peripheral blood samples were taken before PCI, 24 and 72 h after stenting. The plasma concentrations of C-reactive protein (CRP) and interleukin-6 (IL-6) were determined by enzyme-linked immunosorbent assay (ELISA). The clinical and angiographic follow-up was performed at 8 months after stenting.

RESULTS

The data showed that there was no significant difference in clinical and angiographic baseline characteristics between the two groups. The plasma CRP and IL-6 levels at 24 h after stenting were significant higher in both groups compared with baseline (p < 0.01 respectively). Likewise, the CRP levels at 72 h after stenting were also significant higher compared with baseline in both groups (p < 0.01 respectively). However, the plasma levels of IL-6 at 24 h and CRP at 72 h after stenting were higher in PES group compared with SES group (p < 0.05). At 8 months follow-up, the rates of major adverse cardiac events, target lesion revascularization, in-stent and in-segment restenosis were similar in both groups. However, the late loss in both in-stent and in-segment was significantly higher in the PES group than in SES group (p < 0.001 respectively).

CONCLUSIONS

Our findings suggest that a drug-eluting stent implantation could trigger a systemic inflammatory response as previously demonstrated. However, SES implantation results in a lower inflammatory response compared with PES implantation, which seems to be associated with greater late of in-stent and in-segment loss at 8-month follow-up with PES.

Randomized comparison of early inflammatory response after sirolimus-eluting stent vs bare metal stent implantation in native coronary lesions

BACKGROUND

The clinical significance of early inflammatory response after coronary stent implantation has been controversial. Sirolimus-eluting stent (SES) has been shown to be better outcomes compared with bare metal stent (BMS). We prospectively investigated the early inflammatory response after SES or BMS implantation in patients with single-vessel lesion, and evaluated the relationship between inflammation and late clinical outcomes in a randomized design.

METHODS

Forty-eight patients with single-vessel disease were randomized into SES or BMS implantation group (n=24 respectively). Blood samples were taken before stenting, 1 h, 24 h and 8 months afterward. The plasma concentrations of C-reactive protein (CRP) and interleukin-6 (IL-6) were determined by ELISA. The clinical and angiographic follow-up were performed at 8 months after stenting.

RESULTS

There was no difference in baseline characteristics, plasma CRP and IL-6 concentrations between the 2 groups. However, plasma IL-6 concentrations at 1 h after stenting were higher in both groups than in baseline (p<0.01). In addition, the plasma CRP and IL-6 concentrations at 24 h after stenting were significantly higher in both groups compared with baseline (p<0.01 respectively). Likewise, plasma CRP and IL-6 concentrations were significantly higher in BMS group compared with SES group at 24 h after stenting (p<0.05 respectively). At the follow-up (mean 8 months after stenting), the rate of in-stent restenosis (ISR) and target lesion revascularization (TLR) were higher in BMS group than in SES group (p<0.05 respectively) although the plasma CRP and IL-6 concentrations are similar between the groups.

CONCLUSIONS

Single coronary stenting could trigger an early inflammatory response. However, patients undergoing SES implantation has less augmentation of early inflammatory markers after stenting compared to patients treated with BMS, which was positively related the incidence of ISR and TLR at follow-up. This may reflect the potential impact of SES implantation on the early inflammatory response and late clinical outcomes.

The role of inflammation in coronary artery calcification

Vascular calcification is an age-dependent, common finding in human coronary arteries and begins as early as the second decade of life, just after fatty streak formation. Previous studies have showed that the severity of coronary calcification is closely related to atherosclerotic plaque burden and cardiac event rate. In the past few decades, coronary calcification has been considered passive and degenerative. With recent clinical and basic research, however, there is increasing recognition that coronary calcification is an active, regulated process. Current diagnostic methods for coronary artery calcification (CAC) are usually traditional coronary angiography, intravascular ultrasound (IVUS), electron beam computed tomography (EBCT) and multi-slice computed tomography (MSCT) while treatment for patients with calcified coronary arteries is troublesome. Several lines of evidence suggest that inflammation plays a major role in the development of atherosclerosis as well as its clinical manifestations. Recent study showed that inflammatory process might be also involved in coronary calcification. Accordingly, measurements of inflammatory markers such as C-reactive protein (CRP) may in part reflect indices of atherosclerosis, such as coronary calcification, and are likely to provide distinct information regarding cardiovascular risk. In this article, we review the current evidence of relationship between coronary calcification and inflammation for purpose of drawing the more attention on the inflammatory mechanism of coronary calcification, which may change our research as well as therapeutic strategies for coronary calcification in the future.

Renal angioplasty causes a rapid transient increase in inflammatory biomarkers, but reduced levels of interleukin-6 and endothelin-1 1 month after intervention

OBJECTIVE

To examine prospectively whether inflammatory biomarkers and endothelin (ET)-1 are increased in patients with renal artery stenosis (RAS), and to investigate how treatment with percutaneous transluminal renal angioplasty (PTRA) affects these variables during the first month after intervention.

METHODS

One hundred patients with suspected RAS undergoing renal angiography were included. PTRA was performed if the trans-stenotic mean arterial pressure gradient was>or=10 mmHg. High-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNFalpha), neopterin, CD40 ligand (CD40L) and endothelin-1 (ET-1) were measured before, and 1 day and 1 month after PTRA (n=61) or diagnostic angiography only (n=39).

RESULTS

At baseline there were no significant differences in inflammatory biomarkers or ET-1 levels between patients subsequently undergoing PTRA or angiography only. After angiography, IL-6 and hs-CRP had increased in both groups compared to baseline (P<0.001). At this time point hs-CRP (10.90+/-1.48 versus 6.37+/-1.61 mg/l; P<0.05) and IL-6 (13.70+/-0.94 versus 13.00+/-0.17 pg/ml; P<0.01) were higher in the PTRA group than in patients subjected to angiography only. One month after PTRA, systolic blood pressure and levels of IL-6 and ET-1 were lower than before intervention (P<0.05), whereas CD40L had increased compared to baseline (P<0.01).

CONCLUSION

In patients with RAS, PTRA triggers rapid transient increases in hs-CRP and IL-6; however, 1 month after PTRA, both IL-6 and ET-1 had decreased compared to before intervention, indicating beneficial effects of PTRA on inflammation and the endothelin system.

Percutaneous treatment of peripheral vascular disease: the role of diabetes and inflammation

Peripheral arterial disease (PAD) is a growing health problem for many Americans and often occurs along with other cardiovascular risk factors, including diabetes mellitus (DM), low-grade inflammation, hypertension, and lipid disorders. Intermittent claudication (IC), an early manifestation of PAD, commonly leads to reduced quality of life for patients who are limited in their ambulation. While recent wide adoption of percutaneous peripheral interventional (PPI) techniques has increased the number patients being aggressively treated for IC, the overall effectiveness of PPI for the treatment of IC is not well known, especially for DM patients who have both hemodynamic and functional obstacles to treatment success. This review is designed to illustrate how treatment outcomes for IC can be measured by different modalities and how diabetes and inflammation can influence those outcomes. In the setting of greater concern for health care resources and clinical accountability, better understanding of treatment outcomes and efficacy will help us manage these complex challenges.

Coronary restenotic reduction of drug-eluting stenting may be due to its anti-inflammatory effects

The development of coronary stent has revolutionized the field of interventional cardiology by reducing the incidence of restenosis after balloon angioplasty. However, the stent has still associated with a serious complication, namely, in-stent restenosis. Although, restenosis following coronary stenting has long been attributed to neointimal proliferation, thrombosis, and negative remodeling, the inflammation may be a trigger for those vascular reactions following coronary stenting. Both experimental and clinical studies have demonstrated a marked activation of local and systemic inflammatory response following stent implantation, suggesting that inflammation may play an important role in determining in-stent restenosis via neointimal proliferation. The key role of inflammation in vascular healing and in-stent retsenosis has also been increasingly well understood. Recently, drug-eluting stents (DESs) have been shown to decrease in-stent restenosis in a large number of clinical studies. In addition to their anti-proliferative activity, DESs have been considered to possess an anti-inflammatory property, especially for sirolimus-eluting stent compared with bare metal stent. Moreover, the benefit of the anti-inflammatory therapy during the peri-procedural period and long-term follow-up by means of drug administration is also dependent on the inflammatory status during percutaneous coronary intervention. Measurement of cytokine and acute phase proteins, such as C-reactive protein, therefore, may be important to identify high-risk subjects and develop specific treatment tailored to the individual patients with stent restenosis. Thus, therapeutic approach should be further directed toward increasing local resistance to proliferative inflammatory stimuli by means of anti-proliferative, locally delivered drugs and reducing the magnitude and persistence of systemic inflammation.

Is inflammation a contributor for coronary stent restenosis?

The development of coronary stent has revolutionized the field of interventional cardiology by reducing the incidence of restenosis after balloon angioplasty. Despite significant progress in its prevention and treatment, however, in-stent restenosis (ISR) is still common, and remains a challenge for the interventional cardiologist. Restenosis after stent implantation is mainly caused by neointimal proliferation through the stent struts. Currently, there are three major factors has been demonstrated to be contributors for ISR, namely patients-, lesion- and genetic-related factors in large number of clinical trials. However, the triggers and pathophysiological mechanisms for ISR are not fully elucidated. Experimental as well as clinical studies indicate a marked activation of inflammatory cells at the site of stent structs, which are likely to play a key role in the process of neointimal proliferation and stent restenosis. Those data suggest that inflammation may be a major contributor for ISR. In fact, coronary stenting is a strong inflammatory stimulus and the acute systemic response to local inflammation produced by coronary stenting is highly individual and predicts restenosis and event-free survival. Thus, the attention should be paid on anti-inflammatory therapeutic approaches for ISR, and the benefit of anti-inflammatory therapy during the periprocedural period and long-term follow-up is dependent on the inflammatory status. Measurement of cytokine and acute phase proteins, such as C-reactive protein, therefore, may be important to identify high-risk subjects and develop specific treatment tailored to the individual patients.

Rebound phenomenon of inflammatory response may be a major mechanism responsible for increased cardiovascular events after abrupt cessation of statin therapy

Inflammation has been recognized as having an important role in the development and progression of atherosclerosis. Statins reduce cardiovascular events mainly by cholesterol lowering. A large number of investigations have demonstrated that administration of statin could modify inflammatory response with a concurrent fall in cardiovascular events. Despite the known benefit of statin therapy, many cardiac patients abruptly discontinue therapy because of financial constraints, forgetfulness, or side effects. More recently, several studies have shown that abrupt cessation of statin therapy during treatment could increase the incidence of cardiac events in patients with atherosclerotic heart disease. However, the mechanisms of the increased incidence of cardiovascular events after abruptly stopping statin therapy are still unknown. A few data suggest that abrupt withdrawal of statin therapy deteriorates endothelial function, result in expression of pro-inflammatory gene involved in the development and progression of atherosclerosis. We hypothesis that rebound phenomenon of inflammatory response may be a major mechanism responsible for increased cardiovascular events after abrupt cessation of statin therapy. Our very recent data showed that abrupt termination of statin therapy resulted in a rapid increased C-reactive protein (CRP) and interleukin-6 (IL-6) levels in patients with hypercholesterolemia. This finding may be of important interest in the connection between inflammatory response and abrupt withdrawal of statin therapy in patients with coronary artery disease.

Inflammation: a possible pathogenic link to cardiac syndrome X

Cardiac syndrome X is defined as a typical angina pectoris, positive treadmill exercise test, negative intravenous ergonovine test and normal coronary angiography. The pathogenesis of cardiac syndrome X has previously ascribed to myocardial ischemia that may be caused by microvascular dysfunction and increased sensitivity to intracardiac pain. Despite the extensive studies, the pathophysiological mechanisms in cardiac syndrome, however, remain unclear. More recently, the data has been suggested that chronic inflammation has been associated with cardiac syndrome X. The evidence for the hypotheses included that inflammatory marker are increased, and associated with the disease activity in patients with cardiac syndrome X. And also, statin, a lipid-lowering as well as anti-inflammatory drug, has significantly modified the disease process in this special syndrome. Despite the good prognosis of cardiac syndrome X, the chronic, frequent nature of the persistent angina and reduced exercise tolerance can significantly impair quality of life. Thus, lowering inflammatory response by, for example, use of statin and/or aspirin, might improve coronary microvascular dysfunction. Whether this is a valid approach, however, is still unknown and deserves further investigation. Indeed, as mediators of inflammation are multiple, the strategy of identifying triggers and mechanisms of inflammation in each special clinical setting and directing treatment at the special triggers or to rate limiting steps in effector pathways appears more reasonable or a promising strategy.