Search

Scientometric analysis is a useful tool that utilizes bibliometric data to measure scientific output of a disease or region in a particular field. In this report, we comprehensively provide bibliometric characteristics of all the papers on betel quid (BQ)-related cancer and precancerous lesions. There are 1403 papers on BQ-related cancer and precancerous lesions published until 2022 in the Scopus database. China (mainland and Taiwan region), India, United States, and United Kingdom contribute 1214 (86.5%) papers and 34,120 (91.9%) citations of all the papers. The number (457), citations (14,573), and h index (60) of the papers originated from Taiwan region stably remain in the first. The most frequent research keyword is arecoline, followed by drug, prevalence, metabolism, carcinogenesis, and pathology. Areca nut and BQ cessation program by Taiwan government has demonstrated a significant positive impact on oral cancer prevention. Collectively, the scientific output of BQ-related cancer and precancerous field represents distinct regional characteristic. BQ-related cancer prevention is still a long way off. Encouragingly, Taiwan region is well ahead in this way. [ABSTRACT FROM AUTHOR]

The physical and chemical properties of various constitutional ingredients of betel quid (BQ) are well known in the literature. However, BQ as a whole has been rarely investigated for identifying its physical properties that can impact and modulate the disease progression of various pathologies, mainly oral submucous fibrosis (OSMF). It is quite conceivable that in the oral cavity environment, the amalgamated BQ might absorb saliva by virtue of its hygroscopic properties. As a proof of concept, we developed a methodology to quantify the hygroscopicity of the 'whole BQ' when it is mixed with saliva. To the best of our knowledge, this is the first study to report and quantify the hygroscopicity of BQ when mixed with saliva, and this forms a proof of concept for future implications in the pathogenesis of various pathologies. [ABSTRACT FROM AUTHOR]

Cigarette smoking (CS) and betel quid (BQ) chewing are two known risk factors that have synergistic potential for the enhancing the development of oral squamous cell carcinoma (OSCC) in Taiwan. Most mutagens and carcinogens are metabolically activated by cytochrome P450 (CYP450) to exert their mutagenicity or carcinogenicity. Previous studies have shown that metabolic activation of the tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), by CYP2A6 activity determines NNK-induced carcinogenesis. In addition, safrole affects cytochrome P450 activity in rodents. However, the effect of BQ safrole on the metabolism of tobacco-specific NNK and its carcinogenicity remains elusive. This study demonstrates that safrole (1 mg/kg/d) induced CYP2A6 activity, reduced urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) levels, and increased NNK-induced DNA damage, including N7-methylguanine, 8-OH-deoxyguanosine and DNA strand breaks in a Syrian golden hamster model. Furthermore, altered NNK metabolism and increased NNK-induced DNA damage were also observed in healthy subjects with CS and BQ chewing histories compared to healthy subjects with CS histories. In conclusion, BQ containing safrole induced tobacco-specific NNK metabolic activation, resulting in higher NNK-induced genotoxicity. This study provides valuable insight into the synergistic mechanisms of CS- and BQ-induced OSCC. Image 1 • Most carcinogens in CS and BQ are metabolically activated by cytochrome P450. • The carcinogenicity of tobacco-specific nitrosamines NNK is determined by CYP2A6. • Safrole induces CYP2A6 activities in rodent models. • BQ containing safrole induces NNK metabolic activation and NNK-induced genotoxicity. • This provides insight into synergistic mechanisms of CS and BQ-induced oral cancer. [ABSTRACT FROM AUTHOR]

Antiseptic is commonly used in dentistry practices, but some antiseptics have side effects such as allergy. Therefore, natural substances are developed as substitute, i.e betel quid which consisted of betel leaf, areca nut, gambier, and mineral slaked lime. The aim of this study was to determine antiseptic effect of betel quid extract on lip mucosal wound of male Wistar (Rattus norvegicus) rats. This study was true experimental in vivo. Thirty rats were divided into five groups; three groups were treated with betel quid extract ointments at concentration of 5%, 10% and 20%, one group was positive control (hyaluronic acid) and last group was negative control (placebo). One-mm diameter of wound was made on lower lip mucosa of rats with cylinder diamond bur. All wounds were swabbed before and after treatment, and the number of bacterial colonies grown in agar plates were counted. The results showed that there was significant decrease of bacterial colony numbers for respective groups, except for negative control (p < 0.05). Ointment containing 20% betel quid extract had antiseptic effect similar to 0.2% hyaluronic acid. It can be concluded that betel quid extract had antiseptic effect on lip mucosal wound. [ABSTRACT FROM AUTHOR]

Background To investigate the effectiveness of educating program among primary and secondary school students in Papua New Guinea, where has the highest incidence of oral cancer all over the world. Methods A cross-sectional school based survey was arranged in primary and secondary school in Papua New Guinea in June, 2015. A self-administrated questionnaire was administered before and after education done by health experts from Taiwan. The subjects were chosen by random. The schools provided the students we educated and did the questionnaires on. Results Ninety five primary school students and 55 secondary school students in Papua New Guinea participated in the study. Before education, both groups lacked the knowledge that betel quid is harmful to health and had no motivation to quit betel quid consumption with the average score 4.580 out of the total score of 8 for primary school students, and the average score of 4.600 out of the total score of 8 for secondary school students. After education, improvements were noted in knowledge of betel quid among both groups, and reached the statistical significance for secondary school students (mean difference 0.700 ± 0.277, 95% CI 0.164–1.248, p -value = 0.018). Conclusion A great achievement was gained by a short time of education. To prevent the incidence and mortality of oral cancer in Papua New Guinea, education programs should be arranged aggressively and effectively. [ABSTRACT FROM AUTHOR]

Betel quid is a carcinogenic psychoactive preparation, often containing tobacco, which is widely consumed in Myanmar. Studies on betel quid dependence have illuminated betel quid chewers' demographics and reasons for chewing, but dependence fonnation is not fully understood. This study aims to describe the social context, patterns of use, and subjective experiences of betel quid chewing among novice and dependent chewers, and to analyze the hidden structural factors that contribute to the emergence of betel quid dependence. Data on the subjective and objective aspects of betel quid chewing were collected through a five-month ethnographic study in Mandalay, Myanmar. Betel quid chewers were recruited for indepth interviews and focus group discussions. The data were analyzed within a critical medical anthropology framework. Male betel quid chewers begin to chew out of curiosity and social pressure. They believe that chewing boosts their sexual attractiveness and increases their negotiation power with peers and family. Dependence develops when chewers continue chewing beyond the initiation stage. Chewing is used as a social lubricant that enhances social gatherings and work activities. Weak law enforcement and the need for employment among the unskilled rural population encourage the emergence of betel quid economies. Betel quid is used as a drug food to facilitate hard work and to self-medicate suffering caused by exploitative socioeconomic conditions. Betel quid chewing becomes indispensable as a part of the chewer's habitus. The economic conditions of chewers need to be improved and community-based programs initiated to discourage early initiation of betel quid chewing. [ABSTRACT FROM AUTHOR]

Betel quid (BQ), a smokeless chewing tobacco that includes the areca (betel) nut among its ingredients, increases the risk of oral submucous fibrosis (OSMF) and oral cancer, a disease classified as an potentially malignant oral disorder. A wound from the coarse areca nut fibers, as well as the catechin, copper, and alkaloids (e.g., arecoline, arecaidine, guvacoline, and guvacine) in BQ, may stimulate reactive oxygen species (ROS) production, causing myofibroblast differentiation and contraction, fibroblast proliferation, collagen cross-linking, and collagen phagocytosis inhibition, which could result in OSMF and oral cancer. Mitochondria, the primary source of ROS in OSMF, play a crucial role in cellular metabolism. Copper is required for mitochondrial bioenergetics, dynamics, and mitophagy, affecting metabolic reprogramming and cell fate. Given that copper levels are elevated in patients with OSMF, we hypothesize that increased mitochondrial ROS production induced by copper overload and areca nut components may regulate fibrosis-related gene expression and myofibroblast differentiation. Therefore, targeting this fundamental pathomechanism is an appropriate strategy for developing new therapeutic options for OSMF. [ABSTRACT FROM AUTHOR]

The World Health Organization regards betel quid as a human carcinogen, and DSM-IV and ICD-10 dependence symptoms may develop with heavy use. This study, conducted in central Taiwan, investigated whether betel quid chewers can exhibit overt orienting to selectively respond to the betel quid cues. Twenty-four male chewers' and 23 male nonchewers' eye movements to betel-quid-related pictures and matched pictures were assessed during a visual probe task. The eye movement index showed that betel quid chewers were more likely to initially direct their gaze to the betel quid cues, t(23) = 3.70, p < .01, d = .75, and spent more time, F(1, 23) = 4.58, p < .05, η₂ = .17, and were more fixated, F(1, 23) = 5.18, p < .05, η₂ = .18, on them. The visual probe index (response time) failed to detect the chewers' attentional bias. The current study provided the first eye movement evidence of betel quid chewers' attentional bias. The results demonstrated that the betel quid chewers (but not the nonchewers) were more likely to initially direct their gaze to the betel quid cues, and spent more time and were more fixated on them. These findings suggested that when attention is directly measured through the eye tracking technique, this methodology may be more sensitive to detecting attentional biases in betel quid chewers. (PsycINFO Database Record [ABSTRACT FROM AUTHOR]

Background/purpose: Betel quid (BQ) chewing is popular in Taiwan and many other countries. There are about 200-600 million BQ chewers in the world. BQ chewing is one major risk factor of oral cancer and oral submucous fibrosis (OSF). While areca nut (AN), a main component of BQ, exhibits genotoxicity, its transformation capacity and its role in the initiation and promotion stages of carcinogenesis are not fully clear.Methods: Mouse C3H10T1/2 cells were exposed to AN extract (ANE) for 24 hours. Cytotoxicity was evaluated by colony forming efficiency. For the transformation assay, C3H10T1/2 cells were exposed to ANE for 24 hours and then incubated in medium with/without 12-O-tetradecanolylphorbol-13-acetate (TPA; a tumor promoter) for 42 days. Cells were stained with Giemsa and type II and type III transformed foci were counted for analysis of the transformation capacity of ANE.Results: ANE exhibited cytotoxicity to C3H10T/12 cells at concentrations higher than 320 μg/mL as shown by a decrease in colony numbers. ANE (80-640 μg/mL) alone mildly stimulated the transformed foci formation (p > 0.05). In the presence of TPA, ANE (80-640 μg/mL) markedly stimulated the transformed foci formation. The percentage of dishes with foci increased from 0% in controls to 20% in ANE (80 μg/mL and 320 μg/mL)-treated groups and further increased to 65-94% in ANE plus TPA groups.Conclusion: These results indicate that ANE is a weak complete carcinogen. ANE is an effective tumor initiator and can induce malignant transformation of C3H10T1/2 cells in the presence of a tumor promoter. ANE may be involved in multistep chemical carcinogenesis by its malignant transformation capacity. [ABSTRACT FROM AUTHOR]

• Due to coarseness and abrasive action, betel quid chewing causes micro-trauma to the oral mucosa. • This stressor response leads to leader cell formation via activation of the p53-p21-CDK axis. • Due to the chronic nature of the micro-trauma, there is persistence of leader cells. • Continuous activation of the p53-p21-CDK axis can lead to malignant transformation. • This type of leader cell malignancy could be a demographically and biologically distinct entity. Betel quid (BQ) chewing-related oral submucous fibrosis (OSMF) is a common, potentially fatal condition in Southeast Asian countries. The literature has proved that BQ is associated with the development of micro-trauma-related injury to the oral mucosa. This is mainly attributed to the coarseness of the BQ and its abrasive action. Since, BQ chewing is a chronic habit in OSMF patients, it leads to the frequent development of micro-trauma and its repeated healing. This mechanism has been implicated in the pathogenesis of OSMF and its malignant transformation. However, the micro-trauma related mechanism for malignant transformation of OSMF is poorly understood. Leader cell formation is a well-known phenomenon in wound healing characterized by migration guidance to other cells, leading to epithelial repair. Due to repeated trauma and micro-wound formation in OSMF patients, we proposed the persistence of leader cells in the oral mucosa. This causes continuous activation of the p53-p21-CDK axis, which is an integral mechanism required for the transformation of normal epithelial cells into leader cells. We also propose that carcinogens derived from BQ chewing cause genetic and epigenetic changes in the leader cells. Overall, the persistence of leader cells in the oral epithelial population could be a major driver for malignant transformation in OSMF and a determinant of intra-tumoral heterogeneity. Strategies to curtail micro-trauma to the oral mucosa and target the leader cells hold good promise for preventing malignant transformation in OSMF. [ABSTRACT FROM AUTHOR]

The article discusses the carcinogenic effect of consuming the fruit from the palm Areca catechu (L.) or areca nut (AN) and the initiatives to prevent AN consumption. Topics discussed include the steps in chewing AN, the association between developing oral cancer and chewing AN, and the structures of alkaloids and nitroso detected in AN and tobacco and chavibetol.

Background/purpose: Betel quid (BQ) chewing is a popular habit in South-Asian and Southeast Asian countries, and Taiwan. BQ chewing can cause oral cancer and oral submucous fibrosis, and increases the risk of cardiovascular diseases. However, how BQ chewing affects endothelial cells and is involved in cardiovascular diseases and vascular changes is not fully understood. The effects of arecoline, a component of BQ, on the growth and migration of endothelial cells (EAhy 926), and their adherence by U937 cells were investigated. Materials and methods: EAhy926 endothelial cells were cultured and exposed to various concentrations of arecoline for 24 hours. Morphological changes were observed using phasecontrast microscopy. Cytotoxic effects were analyzed using a 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. A wound closure assay was used to evaluate the cellular migration of EAhy926 cells. The attachment of 2',7'-bis-(2-carboxyethyl)-5-(6)-carboxyfluorescein- labeled U937 cells to EAhy926 endothelial cells that were pretreated with various concentrations of arecoline was further studied. Results: The addition of arecoline at concentrations >0.4 mM significantly decreased cellular viability. EAhy endothelial cells showed marked morphological changes, and cellular migration decreased after 24 hours and 48 hours of exposure to arecoline. The number of U937 cells attached to EAhy 926 cells increased when endothelial cells were pretreated by arecoline. Conclusion: Arecoline impaired vascular endothelial cells by inhibiting their growth and migration and their adhesion to U937 mononuclear cells. These results reveal that arecoline may contribute to the pathogenesis of oral submucous fibrosis and cardiovascular diseases by affecting endothelial cell function in BQ chewers. [ABSTRACT FROM AUTHOR]

• Pathogenesis has never been addressed from the perspective of the physical properties of amalgamated betel quid (BQ) with saliva. • Mechanisms related to high osmotic pressure and hygroscopicity of amalgamated BQ are proposed. • Extracellular fluid loss is expected due to the high osmotic pressure and hygroscopicity of amalgamated BQ. • Dense fibrotic bundles observed in oral submucous fibrosis are a manifestation of such extracellular fluid loss, which brings fibers to close together. Increased production and decreased degradation of collagen fibers are the two of hallmarks of oral submucous fibrosis (OSMF). To date pathogenesis of OSMF has been perceived from the perspective of chemical constituents of the betel quid (BQ) and their impact on the signaling pathways related to fibrosis. In the present paper, physical properties such as osmotic pressure and hygroscopicity of the BQ amalgamation formed in the oral cavity are proposed as the causative mechanisms for OSMF. The detailed mechanism of osmotic pressure gradient development between extracellular fluid and the amalgamated BQ in the oral cavity has been deliberated. In addition, the hygroscopicity of BQ is also projected as a complementary mechanism to the osmotic pressure mechanism for OSMF development. Various laboratory experiments, cell culture models, and animal studies are proposed to evaluate the hypothesis. Since OSMF can also occur in only areca nut chewing individuals, we put forth the proposed mechanism as complementary to the already known pathogenesis. This novel hypothesis addresses the age-old problem related to the management of OSMF and extracellular fluid restoration strategies would drastically change and probably improve the clinical status and reduce the malignant potential of OSMF. [ABSTRACT FROM AUTHOR]

Background: This cross sectional study aimed to compare the differences of means score of oral health related quality of life by OHIP-14 among teeth status, general characteristics and daily oral practices among elderly at Purbagram village, Bangladesh. Materials and Methods: A total of 172 elderly about and over 60 years were selected by accidental sampling from Purbagram village. Dental examination to assess teeth status was conducted. Short form of OHIP-14 questionnaire was applied to collect data by interview. Statistics were presented in number and percentage, mean, median, standard deviation, students T-test and ANOVA. Results: The result of the study revealed that more than half of the respondents had 20-28 good teeth (61.4%). Very few of the respondents wear denture (1.7%). More than half of the respondents never brushed their teeth in the morning (64.5%). One-third of the respondents used tooth paste (34.3%). Less than one-third of the respondents were used to smoke regularly (27.9%) Half of the respondents always took betel quid (50.9%). overall mean score of OHIP-14 of the respondents was 22.33 ± 11.29(SD), highest percentage was the item number 7 (poor diet) followed by item number 2 (worsened taste) and item number 4(Discomfort eating food). Only 1.2% of the respondents reported item number 4 very often (inability in function). Item number 14 reported as never more frequently (53.5%) followed by item number 1 (trouble pronouncing words, 52.9%) and 10 (Embarrassment, 52.9%) followed by item number 5 (Feeling self-conscious, 47.1%). Conclusion: The result shows that the mean score of OHIP-14 among the respondents who have 1-19 teeth were higher than who have 20-28 teeth. Elderly with 20-28 teeth had lowest means score of OHIP-14 with the best quality of life related to oral health compare to others. [ABSTRACT FROM AUTHOR]

Abstract: Cancer of the oral cavity is one of the most commonly diagnosed cancers and one of the leading causes of death among men in Taiwan. Extensive research findings have linked betel quid chewing with oral cancer and precancerous conditions. To date, no pharmacological or behavioral treatments exist for betel quid cessation. This paper discusses the potential benefits of applying behavioral research to better understand why betel quid chewers consume betel quid. Specifically, it discusses using behavioral research methods to examine betel quid chewing initiation, dependence, motivation, and withdrawal. Better understanding of these different aspects of betel quid chewing is likely to aid researchers in developing treatment programs. [Copyright &y& Elsevier]

Abstract: Background: We aimed to evaluate the effectiveness of an oral cavity cancer visual screening program conducted in a tertiary academic medical center. We also wanted to determine which group of participants was at greater risk of contracting oral cavity cancer. Methods: Participants were first asked to relate their personal habits during the past 6 months. Visual screening of the oral cavity was then performed under adequate lighting and with proper instruments. Results: From March 2005 to January 2010, 13,878 participants were enrolled in this study. The average age was 54.6 years. Positive lesions were identified in 726 participants (5.2%), and 282 of those participants (2.1%) had oral cavity cancers confirmed. The sensitivity and specificity of this study were 98.9% and 98.7%, respectively. Those participants who were habitual smokers, alcohol consumers, and betel quid chewers had the highest risk of developing oral cavity cancer when compared with those who did not have these habits (odds ratio=46.90, 95% confidence interval=33.15–66.35, p <0.001). Conclusion: The oral screening program conducted in a tertiary medical center was effective. We suggest that individuals aged ≥40 years or who are habitual cigarette smokers, alcohol consumers, and betel quid chewers should receive oral screening regularly so that potential oral cancer can be detected as early as possible. [Copyright &y& Elsevier]

Background/purpose: Betel quid extract (BQE) has been demonstrated to induce matrix metalloproteinase (MMP)-2 expression. This study aimed to establish the possible mechanism involved in this event.Methods: Western blotting, reverse-transcription polymerase chain reaction, and gelatin zymography were used to study the expression level of MMP-2. LY294002, PD98059, U0126, N-acetyl-L-cysteine, SB203580, SP600125, and Bay 11-7082 were used to pretreat OECM-1 cells before BQE treatment and MMP-2 detection.Results: OECM-1 cells were subjected to short-term (10 minutes) or long-term (24 hours) BQE treatment (designated as SBT and LBT, respectively), and we found that both treatments increased MMP-2 protein and extracellular signal-regulated kinase (ERK) phosphorylation levels in a concentration- and time-dependent manner. LBT also increased MMP-2 mRNA level. LBT-induced MMP-2 secretion was not inhibited by PD98059 (up to 50 μM) when ERK was effectively blocked, but was attenuated by LY294002 (0-10 μM) in a concentration-dependent manner. This LBT effect was inhibited strongly by SB203580 (10 μM), SP600125 (10 μM), and Bay 11-7082 (10 μM) and mildly by N-acetyl-L-cysteine (5 mM), but not by U0126 (10 μM).Conclusion: Both SBT and LBT upregulate MMP-2 expression, and LBT-induced MMP-2 expression might be mediated by phosphoinositide 3-kinase, p38 mitogen-activated protein kinase, c-Jun N-terminal kinase, and nuclear factor-κB, and to a lesser extent, by reactive oxygen species, rather than by ERK. [ABSTRACT FROM AUTHOR]

Esophageal cancer is ranked as the sixth most common cause of cancer death worldwide and has a substantial effect on public health. In contrast to adenocarcinoma arising from Barrett''s esophagus in Western countries, the major disease phenotype in the Asia-Pacific region is esophageal squamous cell carcinoma which is attributed to the prevalence of smoking, alcohol, and betel quid chewing. Despite a multidisciplinary approach to treating esophageal cancer, the outcome remains poor. Moreover, field cancerization reveals that esophageal squamous cell carcinoma is closely linked with the development of head and neck cancers that further sub-optimize the treatment of patients. Therefore, preventive strategies are of paramount importance to improve the prognosis of this dismal disease. Since obstacles exist for primary prevention via risk factor elimination, the current rationale for esophageal cancer prevention is to identify high-risk groups at earlier stages of the disease, and encourage them to get a confirmatory diagnosis, prompt treatment, and intensive surveillance for secondary prevention. Novel biomarkers for identifying specific at-risk populations are under extensive investigation. Advances in image-enhanced endoscopy do not just substantially improve our ability to identify small precancerous or cancerous foci, but can also accurately predict their invasiveness. Research input from the basic sciences should be translated into preventive measures in order to decrease the disease burden of esophageal cancer. [Copyright &y& Elsevier]

Betel quid containing areca nut and chewing tobacco is used in many parts of India. In this study we evaluated the micronuclei (MN) in buccal mucosa of healthy individuals from southern India, who were regularly chewing a mixture of betel leaf, areca nut and tobacco. A total of 44 subjects were examined. The study population included 15 chewers, 14 chewers with smoking habit and 15 controls with the mean age of 38.57 ± 0.54, 34.50 ± 0.95, and 33.28 ± 0.89 years, respectively. The mean percentage of MN was 1.90 ± 1.03 in chewers, 2.00 ± 1.12 in chewers with smoking habits and 0.81 ± 0.66 in controls. There was no significant difference between the mean percentages of the two experimental groups. It can be concluded that a mixture of betel leaf, areca nut, and tobacco is unsafe for oral health. [ABSTRACT FROM AUTHOR]

• The high hygroscopic nature of the betel quid is demonstrated with an in-vitro experimentation. • This physical property of can cause rapid absorption of saliva by the quid in the oral cavity. • Compensatory salivary production and secretion is proposed during the betel quid chewing habit. • Prolonged duration and increased frequency of the habit can lead to irreversible damage to salivary acini. • Thus, betel quid chewing mediated xerostomia and related consequences is proposed. Betel quid (BQ) chewing, a highly prevalent habit in Asian countries, is on the rise due to its addictive potential and easy availability in the market. Mostly BQ is placed in the gingivo-buccal sulcus of the oral cavity for a variable period, frequency, and duration. In our recent laboratory experimentation, we observed an extremely high degree of hygroscopicity of BQ when mixed with normal saline and saliva. Based on this observation, we proposed chronic intermittent dryness of the oral cavity for a prolonged period leads to the compensatory secretion of saliva by the acinar cell of salivary glands. However, over a period, this continuous process can cause functional exhaustion of acinar cells and irreversible damage, and ultimately permanent xerostomia. Three-level experimentations (in-vitro, animal, and in-vivo) are proposed for testing the proposed hypothesis. In the future, salivary substitute intervention and stem cell-mediated rejuvenation of the acinar cells can be targeted to effectively achieve symptomatic control over the BQ chewers and oral submucous fibrosis (OSMF) patients. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Dental Hygiene is the property of Canadian Dental Hygienists Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)