Waterpipe effects on pulmonary function and cardiovascular indices: a comparison to cigarette smoking in real life situation

Increased airway resistance among exclusive waterpipe smokers detected using impulse oscillometry

INTRODUCTION

Waterpipe smoking is increasing in popularity, yet the evidence implicating waterpipe smoking in lung disease is limited. We hypothesized that impulse oscillometry (IOS) would detect airway abnormalities in waterpipe smokers (WPS).

METHODS

We studied 210 participants, 40 years or older, from the community, of whom 92 were exclusive WPS and 118 were never-smokers. Waterpipe smoking history was assessed using a validated questionnaire. All participants underwent spirometry, and IOS and absolute and percentage predicted results (for age, sex, height, and weight) were compared between WPS and nonsmokers. The association of IOS parameters with waterpipe smoking duration and extent (waterpipe smoked/day * smoking duration) was evaluated using linear regression.

RESULTS

WPS smoked on average 1.8 ± 1.2 waterpipes/day, over an average duration of 23.3 ± 39.8 years. WPS and nonsmokers were largely asymptomatic and had similar age, body mass index, sex distribution, and spirometric values. Nevertheless, WPS had higher IOS measured resistance at 5Hz compared to nonsmokers, (0.53 ± 0.2 vs. 0.48 ± 0.2 kPa/L/s, P = 0.03) and higher percentage-predicted resistance (124.5 ± 36.3 vs. 115.7% ± 35.6%, P = 0.04). Waterpipe smoking duration was also associated with resistance (β = 0.04 kPa/L/s/year, P = 0.01) and with percentage-predicted resistance (β = 0.05/year, P = 0.02). Waterpipe smoking extent was associated with resistance (β = 0.009 kPa/L/s/waterpipe-year, P = 0.04), while the association with percentage-predicted resistance was near significance (β = 0.009/waterpipe-year, P = 0.07).

CONCLUSIONS

Waterpipe smoking is associated with increased airway resistance assessed by IOS but not by spirometry in largely asymptomatic individuals from the community.

Water-Pipe Smoking Exposure Deregulates a Set of Genes Associated with Human Head and Neck Cancer Development and Prognosis

Water-pipe smoking (WPS) is becoming the most popular form of tobacco use among the youth, especially in the Middle East, replacing cigarettes rapidly and becoming a major risk of tobacco addiction worldwide. Smoke from WPS contains similar toxins as those present in cigarette smoke and is linked directly with different types of cancers including lung and head and neck (HN) carcinomas. However, the underlying molecular pathways and/or target genes responsible for the carcinogenic process are still unknown. In this study, human normal oral epithelial (HNOE) cells, NanoString PanCancer Pathways panel of 770 gene transcripts and quantitative real-time polymerase chain reaction (qRT-PCR) analysis were applied to discover differentially expressed genes (DEG) modulated by WPS. In silico analysis was performed to analyze the impact of these genes in HN cancer patient’s biology and outcome. We found that WPS can induce the epithelial–mesenchymal transition (EMT: hallmark of cancer progression) of HNOE cells. More significantly, our analysis of NanoString revealed 23 genes deregulated under the effect of WPS, responsible for the modulation of cell cycle, proliferation, migration/invasion, apoptosis, signal transduction, and inflammatory response. Further analysis was performed using qRT-PCR of HNOE WPS-exposed and unexposed cells supported the reliability of our NanoString data. Moreover, we demonstrate those DEG to be upregulated in cancer compared with normal tissue. Using the Kaplan–Meier analysis, we observed a significant association between WPS-deregulated genes and relapse-free survival/overall survival in HN cancer patients. Our findings imply that WPS can modulate EMT as well as a set of genes that are directly involved in human HN carcinogenesis, thereby affecting HN cancer patients’ survival.

Short-Term Exposure to Waterpipe/Hookah Smoke Triggers a Hyperactive Platelet Activation State and Increases the Risk of Thrombogenesis

OBJECTIVE

Cardiovascular disease is a major public health problem. Among cardiovascular disease's risk factors, tobacco smoking is considered the single most preventable cause of death, with thrombosis being the main mechanism of cardiovascular disease mortality in smokers. While tobacco smoking has been on the decline, the use of waterpipes/hookah has been rising, mainly due to the perception that they are less harmful than regular cigarettes. Strikingly, there are few studies on the negative effects of waterpipes on the cardiovascular system, and none regarding their direct contribution to thrombus formation. Approach and Results: We used a waterpipe whole-body exposure protocol that mimics real-life human exposure scenarios and investigated its effects, relative to clean air, on platelet function, hemostasis, and thrombogenesis. We found that waterpipe smoke (WPS)-exposed mice exhibited both shortened thrombus occlusion and bleeding times. Further, our results show that platelets from WPS-exposed mice are hyperactive, with enhanced agonist-induced aggregation, dense and α-granule secretion, αIIbβ3 integrin activation, phosphatidylserine expression, and platelet spreading, when compared with clean air-exposed platelets. Finally, at the molecular level, it was found that Akt (protein kinase B) and ERK (extracellular signal-regulated kinases) phosphorylation are enhanced in the WPS and in nicotine-treated platelets.

CONCLUSIONS

Our findings demonstrate that WPS exposure directly modulates hemostasis and increases the risk of thrombosis and that this is mediated, in part, via a state of platelet hyperactivity. The negative health impact of WPS/hookah, therefore, should not be underestimated. Moreover, this study should also help in raising public awareness of the toxic effects of waterpipe/hookah.

The effects of hookah/waterpipe smoking on general health and the cardiovascular system

Hookah or waterpipe smoking or use is an emerging trend in the US population, especially among the youth. The misperception of hookah being less harmful than cigarettes and the availability of different but "appealing" flavors are considered among the main reasons for this trend. Hookah users however are exposed to many of the same toxic compounds/by-products as cigarette users, but at dramatically higher levels, which might lead to more severe negative health effects. In fact, hookah users are at risks of infections, cancers, lung disease, and other medical conditions. Moreover, because of the overlapping toxicant/chemical profile to conventional cigarettes, hookah smoke effects on the cardiovascular system are thought to be comparable to those of conventional cigarettes. A major source of tobacco addiction is nicotine, whose levels in hookah are extremely variable as they depend on the type of tobacco used. Taken together, in this review of literature, we will provide insights on the negative health effects of hookah in general, with a focus on what is known regarding its impact on the cardiovascular system.

Waterpipe Smoking Is Associated with Changes in Fibrinogen, FVII, and FVIII Levels

Cigarette smoking has been shown to be associated with changes in coagulation factors in the circulation and the subsequent thrombosis development. In this study, the impact of waterpipe smoking on the levels of fibrinogen, factor VII (FVII), and factor VIII (FVIII) was investigated. In addition, the effects of waterpipe smoking were compared to those of cigarette smoking and never smokers. A total of 80 male smokers (40 cigarette smokers and 40 waterpipe smokers) and 40 apparently healthy never smokers were recruited in the study. Both waterpipe smoking and cigarette smoking induced significant increases in the plasma levels of fibrinogen, factor VII, and factor VIII (p < 0.01). The magnitude of the increase in fibrinogen levels induced by waterpipe smoking was higher than that induced by cigarette smoking (p < 0.01), while similar increases were observed in other factors (p > 0.05). In addition, in the waterpipe group, the magnitude of the increase in fibrinogen and factor VIII was higher in the smokers with more than 3 years of use (p < 0.05). In conclusion, similar to cigarette smoking, waterpipe smoking modulates the levels of coagulation factors, suggesting its thrombotic potential.

Clinical and radiographic periodontal status and whole salivary cotinine, IL-1β and IL-6 levels in cigarette- and waterpipe-smokers and E-cig users

The aim was to compare the clinical (plaque index [PI], bleeding on probing [BOP], probing pocket depth [PPD] and clinical attachment loss [CAL]) and radiographic (marginal bone loss [MBL]) periodontal parameters and whole salivary cotinine, interleukin (IL)-1β and IL-6 levels among cigarette-smokers, waterpipe-smokers, E-cig users and never-smokers. In total, 154 male individuals (39 cigarette-smokers, 40 waterpipe-smokers, 37 E-cig users and 38 never-smokers) were included. Full mouth PI, BOP, PPD and CAL were measured on all teeth (excluding third molars); and MBL was measured in digital intra-oral radiographs. Unstimulated whole salivary flow rate (UWSFR) and whole salivary cotinine, IL-1β and IL-6 levels were measured. Group comparisons were performed using one way analysis of variance and Bonferroni post-hoc tests. P-values less than 0.05 were considered statistically significant. There was no difference in UWSFR among the groups. Cotinine levels were significantly higher among cigarette- (P < 0.001) and waterpipe-smokers (P < 0.001) and E-cig users (P < 0.001) than never-smokers. IL-1β (P < 0.01) and IL-6 (P < 0.01) levels were significantly higher among cigarette- and waterpipe-smokers than E-cig users and never-smokers. There was no difference in PPD, CAL, mesial and distal MBL and whole salivary IL-1β and IL-6 levels among E-cig users and never-smokers. In conclusion, clinical and radiographic parameters of periodontal inflammation were poorer in cigarette and waterpipe smokers than E-cig users and never-smokers; and whole salivary cotinine levels were similar in all groups. Whole salivary IL-1β and IL-6 levels were higher in cigarette- and waterpipe-smokers than E-cig users and never-smokers.

Waterpipe tobacco smoking among sexual minorities in the United States: Evidence from the National Adult Tobacco Survey (2012-2014)

OBJECTIVE

The current study examined differences in waterpipe smoking (both lifetime and current) comparing sexual minority populations - those identifying with lesbian, gay, or bisexual identity - to their heterosexual counterparts using a nationally representative dataset.

METHODS

The current study used pooled data from the 2012-2013 & 2013-2014 National Adult Tobacco Survey (NATS). Log-Poisson multivariable regression models were deployed to determine the prevalence of waterpipe smoking behavior among sexual minority individuals controlling for sociodemographic characteristics and stratified by current gender status.

RESULTS

In fully-adjusted models assessing lifetime WTS, lesbian/gay and bisexual respondents reported higher prevalence of WTS compared to their heterosexual counterparts. This trend held true in gender-stratified models among gay men [gay men: PR 1.25, 95%CI [1.06, 1.47] and women ([lesbians: PR 1.38, 95%CI [1.12, 1.69] and bisexual women: 1.69, 95%CI [1.45, 1.97]). In fully-adjusted models assessing current WTS, lesbian/gay and bisexual respondents reported higher risk of WTS compared to their heterosexual counterparts. This trend held true in gender-stratified models, only for among gay men [gay men: PR 1.56, 95%CI [1.18, 2.05] and bisexual women: 2.38, 95%CI [1.84, 3.09]).

CONCLUSIONS

Among the US general adult population, sexual minorities exhibited increased prevalence of current waterpipe smoking compared to their heterosexual counterparts. This pattern is also shaped by gender and variation of sexual orientation identification (e.g., lesbian/gay vs. bisexual). This warrants development of tailored interventions aimed at decreasing waterpipe smoking among sexual minority populations.

Toxicological impact of waterpipe smoking and flavorings in the oral cavity and respiratory system

Waterpipe smoking (WS), an emerging trend has major health concerns. It is prevalent worldwide as a recreational activity both indoors and outdoors. The aim of this review was to assess the impact of waterpipe smoke on the oral and respiratory system (oral cavity and pulmonary tissues). A number of studies have shown that periodontal health status is compromised in waterpipe smokers when compared with nonsmokers. Some studies have associated WS with oral premalignant and malignant lesions; however, due to the poor quality of these studies, the presented outcomes should be interpreted with caution. Although cigarette smoking has been considered as a potential risk factor for dental caries; there are no studies in indexed literature that have shown an association to exist between dental caries and WS. Inhaled waterpipe smoke imposes oxidative stress and inflammatory responses and compromises the ventilatory capacity of the lungs and may lead to an increased risk of decline in lung function. WS may cause oral and pulmonary diseases, such as periodontal disease and chronic obstructive airway disease, respectively. The association between WS and development of dental caries and oral pre-cancer and their relationships with chronic airways disease requires investigations. This review discusses the current evidence of waterpipe smoke effects on the oral health and respiratory system based on basic and clinical science and provides future directions for research and regulatory science on how WS can affect the oral cavity and the respiratory/pulmonary system.

Knowledge, attitudes, beliefs and patterns of waterpipe use among Jordanian adults who exclusively smoke waterpipes

BACKGROUND

Widespread waterpipe smoking (WPS) is reported worldwide. Although remarkable numbers of waterpipe smokers do not smoke cigarettes, very few studies have explored the phenomenon of WPS in people who smoke water pipes exclusively. The aim of this study was to assess levels of knowledge, attitudes, beliefs and patterns of WPS among Jordanian waterpipe-only smokers.

METHODS

A cross-sectional descriptive design was used; with 247 participants who were recruited through convenience sampling from 23 cafés offering waterpipes. An interview and self-reported questionnaire was used to collect data.

RESULTS

The average age for starting WPS was 19.4 ± 5.6 years, of whom 71% started as teenagers. Participants like WPS because they like its flavor and social environment (46.3% and 29.5% respectively). The majority of participants reported that they smoked a waterpipe for the first time with their friends (66.8%), they usually smoke in the company of others (63.2%), and believe that quitting cigarettes smoking is harder than quitting WPS (61.6%). More than half (56.7%) of participants have extremely poor knowledge about the health effects of WPS. Participants who had smoked cigarettes in the past, were more knowledgeable than those who had never smoked cigarettes. The majority of participants, and specifically women, have high positive feelings and emotions (attitude) toward WPS, and 88.3% of them reported that it is a socially acceptable behavior.

CONCLUSIONS

Waterpipe smoking participants started WPS at an early age, and are attracted to the social environment that accompanies WPS. Participants have high positive attitude about WPS however they lack knowledge about harmful health effects of WPS.

Increasing popularity of waterpipe tobacco smoking and electronic cigarette use: Implications for oral healthcare

Cigarette smoking increases the risk of developing several systemic conditions including cancer, cardiovascular and pulmonary diseases. Cigarette smoking is also detrimental to oral health as it increases the incidence and severity of oral cancer, periodontal diseases and peri-implantitis, as well as impacting negatively on the dental patients' response to therapy. Therefore, consideration of smoking behavior and recommendation of smoking cessation are important parts of dental treatment planning. However, cigarettes are no longer the most popular form of tobacco use among adolescents in the United States and globally. In recent years, tobacco smoking using a waterpipe ("hookah," "shisha") and use of electronic cigarettes (ECIGs) has increased significantly. Thus, dental clinicians likely will treat more patients who are waterpipe and/or ECIG users. Yet, the literature on the health effects of waterpipe and ECIGs use is sparse. Both waterpipe and ECIGs deliver the dependence-producing drug nicotine. Waterpipe tobacco smoking has been associated with periodontitis, dry socket, premalignant lesions, and oral and esophageal cancer. The health effects of long-term ECIG use are unknown. The purpose of this review is to inform healthcare professionals about waterpipes and ECIGs, highlight emerging evidence on the biological effects of these increasingly popular tobacco products, and introduce perspectives for dental patient management and future research.

Motivation to quit smoking and acceptability of shocking warnings on cigarette packages in Lebanon

INTRODUCTION

Health warnings on tobacco packages have been considered an essential pillar in filling the gap of knowledge and communicating the health risks of tobacco use to consumers. Our primary objective was to report the perception of smokers on the textual health warnings already appearing on tobacco packages in Lebanon versus shocking pictures about the health-related smoking consequences and to evaluate their impact on smoking behaviors and motivation.

METHODS

A pilot cross-sectional study was undertaken between 2013 and 2015 in five hospitals in Lebanon. Participants answered a questionnaire inquiring about sociodemographic characteristics, chronic respiratory symptoms, smoking behavior and motivation to quit smoking. Only-text warning versus shocking pictures was shown to the smokers during the interview.

RESULTS

Exactly 66% of the participants reported that they thought shocking pictorial warnings would hypothetically be more effective tools to reduce/quit tobacco consumption compared to only textual warnings. Also, 31.9% of the smokers who were motivated to stop smoking reported that they actually had stopped smoking for at least 1 month secondary to the textual warnings effects. A higher motivation to quit cigarette smoking was seen among the following groups of smokers: males (odds ratio [OR] =1.8, P=0.02), who had stopped smoking for at least 1 month during the last year due to textual warning (OR =2.79, P<0.001), who considered it very important to report health warning on cigarette packs (OR =1.92, P=0.01), who had chronic expectoration (OR =1.81, P=0.06) and who would change their favorite cigarette pack if they found shocking images on the pack (OR =1.95, P=0.004).

CONCLUSION

Low-dependent smokers and highly motivated to quit smokers appeared to be more hypothetically susceptible to shocking pictorial warnings. Motivation to quit was associated with sensitivity to warnings, but not with the presence of all chronic respiratory symptoms.

Validation of asthma control questionnaire and risk factors affecting uncontrolled asthma among the Lebanese children's population

OBJECTIVES

To validate the Arabic version of the Asthma Control Test (ACT) in asthmatic children in Lebanon and identify risk factors that might affect asthma control in these children.

METHODS

This study, conducted between December 2015 and April 2016, included 300 children.

RESULTS

A high Cronbach's alpha was found for the full scale (0.959). The correlation factors between each item of the ACT scale and the whole scale ranged between 0.710 and 0.775(p < 0.001 for all items). Low mother's educational level as well as the history of asthma in the mother and the father would significantly increase the risk of uncontrolled asthma (p = 0.001; Beta = 1.862; p < 0.001; Beta = 3.534; p < 0.001; Beta = 1.885respectively). Cigarette smoking during breastfeeding and waterpipe smoking by the mother during pregnancy were both significantly associated with uncontrolled asthma (p = 0.005; Beta = 2.105 and p = 0.041; Beta = 2.325 respectively). The high mother's level of education was significantly associated with more asthma control (p = 0.008; Beta = -0.715).

CONCLUSION

The Arabic version of the asthma control questionnaire is a valid tool to use in pediatric patients in the Lebanese population to assess asthma control. Waterpipe smoking during pregnancy and cigarette smoking during breastfeeding, as well as the lower education level are risk factors for uncontrolled asthma. Spreading awareness among health care professionals, as well as reinforcing health education seem to be an important step toward a better asthma control.

Waterpipe tobacco smoking and its human health impacts

Waterpipe tobacco smoking (WTS, also known as hookah, shisha, narghile, and many other names) involves passing tobacco smoke through water prior to inhalation by the consumer. As the number of waterpipe smokers is rising rapidly, there is growing concern over the use of WTS, particularly as there has been a widely held misconception that WTS is free from health hazards. In reality, it is associated with a variety of adverse health outcomes on both a short- and long-term basis. Hence, it is desirable to develop advanced techniques for surveillance, intervention, and regulatory/policy frameworks specific to the production and use of waterpipe tobacco. This review is written to survey the types and extent of pollutants released from its use and their potential health risks. A review of the present regulation guidelines is also included.

Waterpipe smoking and risk of coronary artery disease

PURPOSE OF REVIEW

Smoking tobacco using a water pipe is becoming more prevalent globally, particularly amongst younger populations. In addition to its growing popularity, more evidence is emerging regarding associated harm, and several misconceptions exist concerning the likely adverse health effects of waterpipe smoking (WPS). It is timely, therefore, to examine the body of evidence linking WPS to coronary artery disease (CAD). Here, we review the direct evidence linking WPS to CAD and examine additional, indirect evidence of associated harm. We discuss the clinical and public health implications of the current evidence and provide suggestions for further research.

RECENT FINDINGS

A multicentre case-control study in Lebanon has recently demonstrated an association between WPS and CAD. There are few prior studies making this direct link. However, a large body of evidence has emerged showing close similarities between WPS and cigarette smoking with regard to the toxicity of smoke and acute inflammatory and haemodynamic effects following exposure to it.

SUMMARY

There are consistent similarities between WPS and cigarette smoking in regard to association with CAD, the nature of the smoke produced, and the acute haemodynamic effects and inflammatory responses that follow exposure. These findings justify both public health and clinical interventions to reduce WPS. Further studies are warranted to confirm a causal association between WPS and CAD.

A Systematic Review of Effects of Waterpipe Smoking on Cardiovascular and Respiratory Health Outcomes

BACKGROUND

Waterpipe smoking (WPS) is a social custom common in many Middle Eastern, North African, and Asian countries and has become increasingly popular in the US, especially among youth; however, WPS smoking may be increasing in the US adult population as well. There is a common belief among waterpipe (WP) smokers that WPS is less harmful than smoking cigarettes. Thus, this review aims to systematically explore the literature on the effects of WP tobacco smoking with a particular focus on cardiovascular and respiratory health outcomes as well as on oxidative stress, immunity, and cell cycle interference health outcomes.

METHODOLOGY

We conducted a systematic review, guided by the criteria of The Preferred Reporting Items for Systematic Reviews and Meta-Analyses, using the following online databases MEDLINE, CINAHL, ScienceDirect, PMC, and Cochrane Library. Results were summarized qualitatively.

RESULTS

Forty studies met the inclusion criteria established for this review. Based on the existing evidence, several cardiovascular and respiratory physiologic health indicators and conditions have been shown to be negatively affected by WPS. In addition to the effects of nicotine and chemical toxicant exposures, WPS was significantly associated with an increase in heart rate, blood pressure, and lower pulmonary function test results, as well as a number of health conditions such as lung cancer, alterations in oxidative stress, immunity, and cell cycle interference.

CONCLUSION

The current literature provides evidence that WPS is associated with a number of negative health indicators and outcomes. There is need for more research related to WPS and its effects on health so that appropriate campaigns and prevention interventions can be implemented to control the epidemic increase of WPS in the US.

Health effects associated with waterpipe smoking

OBJECTIVE

It is widely held that waterpipe smoking (WPS) is not associated with health hazards. However, several studies have documented the uptake of several toxicants and carcinogens during WPS that is strongly associated with harmful health effects. This paper reviews the literature on the health effects of WPS.

DATA SOURCES

Three databases-PubMed, MEDLINE and EMBASE-were searched until August 2014 for the acute and long-term health effects of WPS using the terms 'waterpipe' and its synonyms (hookah, shisha, goza, narghileh, arghileh and hubble-bubble) in various spellings.

STUDY SELECTION

We included original clinical studies, case reports and systematic reviews and focused on clinical human studies. ∼10% of the identified studies met the selection criteria.

DATA EXTRACTION

Data were abstracted by all three authors and summarised into tables. Abstracted data included study type, results and methodological limitations and were analysed jointly by all three authors.

DATA SYNTHESIS

WPS acutely leads to increased heart rate, blood pressure, impaired pulmonary function and carbon monoxide intoxication. Chronic bronchitis, emphysema and coronary artery disease are serious complications of long-term use. Lung, gastric and oesophageal cancer are associated with WPS as well as periodontal disease, obstetrical complications, osteoporosis and mental health problems.

CONCLUSIONS

Contrary to the widely held misconception, WPS is associated with a variety of adverse short-term and long-term health effects that should reinforce the need for stronger regulation. In addition, this review highlights the limitations of the published work, which is mostly cross-sectional or retrospective. Prospective studies should be undertaken to assess the full spectrum of health effects of WPS, particularly in view of its growing popularity and attractiveness to youth.

Use & Misuse of Water-filtered Tobacco Smoking Pipes in the World. Consequences for Public Health, Research & Research Ethics

BACKGROUND

The traditional definition of an "epidemic" has been revisited by antismoking researchers. After 400 years, Doctors would have realized that one aspect of an ancient cultural daily practice of Asian and African societies was in fact a "global "epidemic"". This needed further investigation particularly if one keeps in his mind the health aspects surrounding barbecues.

METHOD

Here, up-to-date biomedical results are dialectically confronted with anthropological findings, hence in real life, in order to highlight the extent of the global confusion: from the new definition of an "epidemic" and "prevalence" to the myth of "nicotine "addiction"" and other themes in relation to water filtered tobacco smoking pipes (WFTSPs).

RESULTS

We found that over the last decade, many publications, -particularly reviews, "meta-analyses" and "systematic reviews"- on (WFTSPs), have actually contributed to fuelling the greatest mix-up ever witnessed in biomedical research. One main reason for such a situation has been the absolute lack of critical analysis of the available literature and the uncritical use of citations (one seriously flawed review has been cited up to 200 times). Another main reason has been to take as granted a biased smoking robot designed at the US American of Beirut whose measured yields of toxic chemicals may differ dozens of times from others' based on the same "protocol". We also found that, for more than one decade, two other main methodological problems are: 1) the long-lived unwillingness to distinguish between use and misuse; 2) the consistent unethical rejection of biomedical negative results which, interestingly, are quantitatively and qualitatively much more instructive than the positive ones.

CONCLUSION

the great majority of WFTSP toxicity studies have actually measured, voluntarily or not, their misuse aspects, not the use in itself. This is in contradiction with both the harm reduction and public health doctrines. The publication of negative results should be encouraged instead of being stifled.