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At least 271 records · Page 15Linked to original sources
PubMed2006

Morphogenesis of rat experimental pulmonary emphysema induced by intratracheally administered papain: changes in elastic fibres.

The ultrastructural changes of elastic fibres in emphysematous lungs have been studied in men, but few works exist on this topic in experimental emphysematous animals. In this paper, the morphogenesis of emphysema and alterations of the elastic fibres produced by the instillation of papain are described by light and electron microscopy. Wistar rats were instilled through the trachea with papain at a rate of 3 mg/100 g animal weight. The animals were sacrificed 12 h, 3 days, 10 days and 60 days after enzyme instillation. The "Mean Linear Intercept" (MLI), the "Number of fenestrations/respiratory units" (NF) the "Number of macrophages per mm of alveolar wall" (NM) and the "Number of respiratory unit/mm2" (RU), both in the control and experimental groups were studied. Two months after treatment, the experimental group showed a strong increase in the MLI (p<0.001) and NF (p<0.001), and a diminished number of RU (p<0.05) compared with the control group. Partial correlation analysis showed a positive correlation only between MLI and NF. Twelve hours after papain instillation an inflammatory response was observed, the elastic fibres were ruptured, while the microfibrilar component remained. New formations of eulanin elastic fibres were observed three days post papain instillation. After ten days the interalveolar oedema had disappeared and the elastic fibres were of normal morphology although irregular groups of strips of elastic fibres were evident. A mixed pattern of panlobular, centrilobular and normal lung zones were observed. Two months after papain instillation abundant accumulations of elastic fibres of irregular outline were observed associated to collagen fibres. In conclusion, the morphometric parameters studied showed a significant progression of the emphysema. The strong correlation between NF and MLI suggested that papain-induced emphysema is principally caused by breaches of the alveolar walls. The results seem to point to a very abnormal remodelling process associated with elastic fibre regeneration, although there were no signs of destruction of these new fibres formed in emphysematous rat lung induced by papain.

Animals↗
PubMed2004

Effects of aging and postmenopausal hypoestrogenism on skin elasticity and bone mineral density in Japanese women.

Skin collagen content and bone mass decrease with aging. Loss of collagen from the skin might decrease its elasticity. We investigated associations between skin elasticity, bone mineral density (BMD), age, and menopausal hypoestrogenism. Thirty-eight healthy Japanese postmenopausal women were studied (mean age, 55.7 +/- 5.9 yr; range, 48 to 71). Skin elasticity was measured using a suction device applied to the dorsal right forearm. BMD values of L2 to 4 vertebral bodies were measured by dual-energy X-ray absorptiometry. Age showed significant negative correlations with both skin elasticity and BMD (r = -0.57, p<0.001 and r = -0.40, p<0.05, respectively). Years since menopause also showed significant negative correlations with both skin elasticity and BMD (r = -0.51, p<0.01 and r = -0.41, p<0.05, respectively). We also found a positive correlation between skin elasticity and BMD in these postmenopausal women (r = 0.44, p<0.01). In conclusion, we demonstrated declining skin elasticity and bone mass in postmenopausal women to possibly be age- and estrogen-related. Additionally, decreased skin elasticity might serve as a predictor of bone loss in postmenopausal women.

Absorptiometry, Photon↗
PubMed2005

The counterbend phenomenon in dynein-disabled rat sperm flagella and what it reveals about the interdoublet elasticity.

Rat sperm that have been rendered passive by disabling the dynein motors with 50 muM sodium metavanadate and 0.1 mM ATP exhibit an interesting response to imposed bending. When the proximal flagellum is bent with a microprobe, the portion of the flagellum distal to the probe contact point develops a bend in the direction opposite the imposed bend. This "counterbend" is not compatible with a simple elastic beam. It can be satisfactorily explained by the sliding tubule model of flagellar structure but only if there are permanent elastic connections between the outer doublets of the axoneme. The elastic component that contributes the bending torque for the counterbend does not reset to a new equilibrium position after an imposed bend but returns the flagellum to a nearly straight or slightly curved final position after release from the probe. This suggests it is based on fixed, rather than mobile, attachments. It is also disrupted by elastase or trypsin digestion, confirming that it is dependent on a protein linkage. Adopting the assumption that the elasticity is attributed to the nexin links that repeat at 96 nm intervals, we find an apparent elasticity for each link that ranges from 1.6 to 10 x 10(-5) N/m. However, the elasticity is nonlinear and does not follow Hooke's law but appears to decrease with increased stretch. In addition, the responsible elastic elements must be able to stretch to more than 10 times their resting length without breakage to account for the observed counterbend formation. Elasticity created by some type of protein unfolding may be the only viable explanation consistent with both the extreme capacity for extension and the nonlinear character of the restoring force that is observed.

Animals↗
PubMedDate not supplied

Age related changes in the elastic fiber system of the interfoveolar ligament.

In order to evaluate age related changes of the elastic fiber system in the interfoveolar ligament, we studied the deep inguinal ring from 33 male cadavers aged from stillborn to 76 years. Selective and alternated staining methods for elastic fibers were performed to differentiate oxytalan, elaunin, and mature elastic fibers. We confirmed quantitative changes of the elastic fiber system with aging. There was a significant and progressive reduction of the oxytalan fibers (responsible for tissue resistance) and a significant increment in the mature elastic and elaunin fibers (responsible for tissue elasticity). Furthermore, there were structural changes in the thickness, shortness and curling of these mature elastic fibers. These changes induced loss of the elastic fiber function and loss of the interfoveolar ligament compliance. These factors predispose individuals to the development of indirect inguinal hernias that frequently emerge in adults and aged individuals, especially above the fifth decade.

Adolescent↗
PubMed2003

Quantitative analysis of collagen and elastic fibers in the transversalis fascia in direct and indirect inguinal hernia.

PURPOSE: Our previous studies demonstrated structural and quantitative age-related changes of the elastic fibers in transversalis fascia, which may play a role in inguinal hernia formation. To verify whether there were differences in the extracellular matrix between direct and indirect inguinal hernia, we studied the amount of collagen and elastic fibers in the transversalis fascia of 36 male patients with indirect inguinal hernia and 21 with direct inguinal hernia. MATERIAL AND METHODS: Transversalis fascia fragments were obtained during surgical intervention and underwent histological quantitative analysis of collagen by colorimetry and analysis of elastic fibers by histomorphometry. RESULTS: We demonstrated significantly lower amounts of collagen and higher amounts of elastic fibers in transversalis fascia from patients with direct inguinal hernia compared to indirect inguinal hernia patients. The transversalis fascia from direct inguinal hernia patients showed structural changes of the mature and elaunin elastic fibers, which are responsible for elasticity, and lower density of oxytalan elastic fibers, which are responsible for resistance. These changes promoted loss of resiliency of the transversalis fascia. CONCLUSION: These results improve our understanding of the participation of the extracellular matrix in the genesis of direct inguinal hernia, suggesting a relationship with genetic defects of the elastic fiber and collagen synthesis.

Adult↗
PubMed2000

A comparative study of aging of the elastic fiber system of the diaphragm and the rectus abdominis muscles in rats.

In the present study the age-related changes of the striated muscle elastic fiber system were investigated in the diaphragm and rectus abdominis muscles of 1-, 4-, 8- and 18-month-old rats. The activation patterns of these muscles differ in that the diaphragm is regularly mobilized tens of times every minute during the entire life of the animal whereas the rectus abdominis, although mobilized in respiration, is much less and more irregularly activated. The elastic fibers were stained by the Verhoeff technique for mature elastic fibers. Weigert stain was used to stain mature and elaunin elastic fibers, and Weigert-oxone to stain mature, elaunin and oxytalan elastic fibers. The density of mature and elaunin elastic fibers showed a progressive increase with age, whereas the amount of oxytalan elastic fibers decreased in both diaphragm and rectus abdominis muscles and their muscular fasciae. These age-related quantitative and structural changes of the elastic fiber system may reduce the viscoelastic properties of the diaphragm and rectus abdominis muscles, which may compromise the transmission of tensile muscle strength to the tendons and may affect maximum total strength.

Aging↗
PubMedDate not supplied

Cortical elasticity in aging rats with and without growth hormone treatments.

This study quantified the orthotropic elastic changes in cortical bone due to aging as well as determined any elastic changes after acute treatments of growth hormone (GH). Three groups of twenty rats represented three age groups of young adult (9 months), middle age (20 months), and old (31 months) rats. During a ten day period, half of the rats in each age group were given twice-daily doses of recombinant human GH while the remaining half were injected with a vehicle control (saline). The effects of aging and GH on the elastic characteristics of cortical bone were quantified via ultrasonic wave propagation. Propagation velocities of longitudinal and shear waves were measured through cubic cortical specimens from the posterior femoral diaphysis. Density was measured by Archimedes' technique. The normalized, orthotropic elastic properties of Young's moduli (Eii), shear moduli (Gij), and Poisson's ratios (Vij) were calculated and used to compare the groups (where i and j = 1, 2, or 3 reference the radial, circumferential, and longitudinal axes, respectively). Cortical elastic moduli consistently increased with age with the strongest effects demonstrated in radial dependent properties such as E11 (+ 25.3% from 9 to 31 months, p = 0.0004) and G12 (+ 12.6% from 20 to 31 months, p = 0.0419). The ratio of transverse to axial displacement (Poisson's ratio) typically decreased with age (9 to 31 months) as seen in V31 (-24.95%, p = 0.0134) and V32 (-20.7%, p = 0.0015). Overall, a ten day treatment with GH produced no global statistical change in elastic properties (p > 0.05). However, GH did minimize the age related differences that were measured for E22, E33, and V32 between the 9 and 31 month old groups essentially returning old bone to its youthful elastic state. These finding add orthotropic detail to the current understanding of changing cortical elastic properties during aging as well as providing a reference for further studies of GH.

Aging↗
PubMed1990

Pulmonary elastic fibers in normal human development and in pathological conditions.

Normal human pulmonary elastic fiber development and development in some pathological conditions were examined using elastic stains by light microscopy, electron microscopy, and immunohistochemistry. In normal development elastic fibers, composed mainly of microfibrils, first appeared around primitive bronchioles at 10 weeks of gestation. As they matured, their appearance became more amorphous, and they extended into the peripheral alveolar walls. Development of elastic fibers was retarded in the hypoplastic lungs of the oligohydramnios syndrome, diaphragmatic hernia, and hydrops fetalis. Elastic development was also retarded in congenital pulmonary lymphangiectasia and in focal areas of lungs with pulmonary dysplasia. Distribution of well-developed elastic fibers was found around the dilated bronchioles and alveoli in cases of congenital cystic adenomatoid malformation and extralobar pulmonary sequestration. Elastic fibers were distributed irregularly and unevenly in the lungs of bronchopulmonary dysplasia and ventilated cases of Wilson Mikity syndrome. In addition, four very immature infants who had progressively deteriorating respiratory function showed an almost total lack of elastic fibers in their alveolar walls.

Chronic Disease↗
PubMed1977

The pressure-volume function of brain elasticity. Physiological considerations and clinical applications.

The intracranial pressure-volume function as determined by brain elasticity is reported in normal dogs. Rapid subarachnoid infusions clearly define an exponential relationship between pressure and volume. An aliquot technique to measure elastance (dP/dV) at multiple intracranial pressures demonstrates a linear relationship between elastance and pressure. This follows mathematically from the exponential nature of the basic pressure-volume function. The clinical significance of brain elastance measurements is discussed. It is emphasized that the effects of pressure on CSF dynamics are superimposed on the pressure-volume function of brain elasticity and probably account for the process of spatial compensation for an expanding mass lesion. It is not apparent that elastance measurements can serve as indicators of impending decompensation, since the pressure-volume function of brain elasticity provides no direct information about CSF dynamics. Accordingly, the clinical usefullness of elastance measurements is seriously questioned.

Animals↗
PubMed1989

[Evaluation of super-elasticity characteristics of orthodontic Ni-Ti alloy wire].

Mechanical properties of orthodontic Ni-Ti alloy wires, especially their super-elasticity characteristics, were investigated in order to use them effectively in the clinics. In this study, twenty commercial orthodontic Ni-Ti wires were tested and two parameters were devised for the load-deflection curve and introduced to evaluate the practical mechanical properties, one being the "super-elastic index: SEI" for super-elasticity, and the other being the "E-load" for the load in the super-elastic region. There was a "flat area" in the load-deflection curve of the super-elastic type of Ni-Ti alloy wires, whose SEI was above seventy and a continuous force could be used through the wide range of deflection. The load of the work-hardened type of Ni-Ti wires, SEI below thirty, was nearly proportional to the deflection. And the middle type showed intermediate properties of the two. The E-load values of the super-elastic type wires are thought to indicate the load level in the super-elastic region. The quantitative evaluation of the super-elasticity characteristics of the orthodontic Ni-Ti wires became possible by the introduction of these parameters.

Dental Alloys↗
PubMed2002

[Scanning electronic microscope observation of elastic fiber of anastomosed artery].

OBJECTIVE: To observe the architecture of elastic fiber of anastomosed artery. METHODS: The right femoral arteries of 60 Wistar rats were cut off transversely and end-to-end anastomosis were performed. On the 3rd, 7th, 14th, 21st, 30th and 90th days after operation, the anastomosed artery segments were harvested and fixed by 10% formalin. After routine processed, the architecture of elastic fiber of anastomosed artery was observed under scanning electronic microscope and was compared with that of normal artery. RESULTS: On the 3rd and 7th days after anastomosis, there was no the elastic fiber in the middle of the anastomosed area. From 14 to 90 days after anastomosis, the newborn elastic fiber connected the anastomosed area. The reconstruction of elastic fiber could be divided into quiescent stage, proliferation stage, and rebuilding stage. CONCLUSION: The reconstruction of elastic fiber occurs after arterious anastomosis and newborn elastic fiber originates from endoarterious layer. The structure of elastic fiber can return to normal 30 days after anastomosis.

Anastomosis, Surgical↗
PubMed2003

Transthoracic echocardiographic assessment of proximal ascending aorta elasticity in familial heterozygous hypercholesterolemia patients.

BACKGROUND: Decreased elasticity of the aorta is associated with aging and several risk factors of atherosclerosis. The data regarding this phenomenon in patients with familial hypercholesterolemia are rather sparse. OBJECTIVES: To evaluate non-invasively the elasticity of the proximal ascending aorta of 51 heterozygous FH patients compared to 42 normal age and gender-matched controls. METHODS: Aortic elasticity was estimated by transthoracic echocardiography using the "pressure-strain" elastic modulus and aortic strain formulas. RESULTS: The elastic modulus score was higher in the FH group than in the controls (1.12 +/- 0.91 10(6) dynes/cm2 vs. 0.65 +/- 0.46 10(6) dynes/cm2 respectively, P = 0.01). This was consistent in both the pediatric (0.5 +/- 0.2 10(6) dynes/cm2 vs. 0.4 +/- 0.1 10(6) dynes/cm2 respectively, P = 0.009) and adult subgroups (1.3 +/- 1.0 10(6) dynes/cm2 vs. 0.8 +/- 0.5 10(6) dynes/cm2 respectively, P = 0.0004). Aortic strain was significantly lower in patients with FH than in controls (6 +/- 4% vs. 9 +/- 5% respectively, P = 0.0002). These findings reflected decreased elasticity of the proximal ascending aorta in the FH patients. In multivariate analysis, age, serum cholesterol level and serum triglycerides level were the independent predictors of the elastic modulus score, whereas age was the predictor of aortic strain. CONCLUSIONS: The elasticity of the proximal ascending aorta is decreased in heterozygous FH patients.

Adolescent↗
PubMed2004

Probing the elastic nature of spider silk in pursuit of the next designer fiber.

Spider silk, one of nature's greatest accomplishments, has a combination of strength and elasticity that is unrivaled. Spiders produce up to 7 different silks; each one with a unique combination of tensile strength and elasticity that allows the spiders' web to hold prey while being resilient enough not to break upon impact. In an attempt to determine the sequences responsible for these enviable mechanical properties, several different amino acid motifs have been defined. Much of the recent work is now concentrated on correlating amino acid motifs with a specific mechanical property. The current hypothesis is that the strength property of spider silk is conferred by a poly-alanine or alanine rich (An or GAn) motif whereas the elastic nature of spider silk is conferred by the amino acid motif, GPGXX, where X is Q, S, A, G, or Y. Despite the fact that these different motifs are now known, the combination of strength and elasticity are yet to be duplicated ex vivo. In an attempt to verify that the GPGXX motif imparts elasticity to the spider silk, the number of repeats and/or the amino acid composition of the Argiope aurantia "elastic motif" were varied and expressed in various strains of E. coli to change the elastic properties of the resulting film and/or fiber. Concurrent with work on the elasticity motif is ongoing work on the strength module. Understanding these two different motifs will aide efforts to produce a designer biomaterial for medical, commercial, and military applications.

Amino Acid Sequence↗
PubMed2005

[A study of association between age-related circulating endothelial progenitor cells and arterial elasticity].

OBJECTIVE: Reduced arterial elasticity is a hallmark of aging in healthy humans independently of diseases and endothelial-cell injury and dysfunction may be responsible for this fall in arterial elasticity. We hypothesized that circulating endothelial progenitor cells (EPCs) are involved in endothelial repair and that lack of EPCs contributes to impaired arterial elasticity. METHODS: A total of 56 healthy male volunteers were divided into young (n = 26) and elderly (n = 30) groups. Large and small artery elasticity indices were non-invasively assessed by using pulse wave analysis. Flow cytometer was used to count the number of circulating CD34(+) mononuclear cells (MNCs), which were isolated from peripheral blood by Ficoll density gradient centrifugation, and then the cells were plated on fibronectin-coated culture dishes. EPCs were characterized as adherent cells double positive staining for DiI-acLDL uptake and lectin binding with using fluorescent microscope. RESULTS: C(1) (large artery elasticity index) and C(2) (small artery elasticity index) were significantly reduced in the elderly group compared with those in the young group (11.73 +/- 1.45 vs 16.89 +/- 1.69 ml/mm Hg x 10, P < 0.001; 8.40 +/- 1.45 vs 10.58 +/- 1.18 ml/mm Hg x 100, P < 0.001 respectively). In parallel, the number of circulating EPCs was significantly reduced in the elderly group compared with the young group (0.13 +/- 0.02 vs 0.17 +/- 0.04%, P < 0.05). The number of circulating EPCs correlated with C(1) large and C(2) small artery elasticity indices (r = 0.47, P < 0.01; r = 0.4, P < 0.01). Fluorescent microscope was used to identify EPCs, which were double positive staining for DiI-acLDL uptake and lectin binding. CONCLUSION: The present findings suggested that the fall in circulating EPCs with subsequently impaired endothelial-cell repair and function might contribute to reduced arterial elasticity in humans with aging. The decrease in circulating EPCs could serve as a surrogate biologic measure of vascular function and human age.

Adult↗
PubMed1992

Middermal elastolysis in an elderly man with evidence of elastic fiber phagocytosis.

BACKGROUND: Middermal elastolysis is a clinically and histologically distinct entity. This idiopathic loss of dermal elastic fibers has mostly been reported in younger adults. To our knowledge, the present case, which has been followed up for 4 years, is the first to occur in an elderly man. OBSERVATIONS: Two years after the onset of progressive wrinkling of the upper aspect of the thorax, the patient underwent a biopsy. Histologic examination of the specimens confirmed previous findings of middermal elastolysis. Examination of extracutaneous elastic tissue showed normal findings. Electron microscopy demonstrated elastic fibers embraced by macrophages, which is suggestive of elastic fiber phagocytosis. For the following 4 years, the patient has remained in stable clinical condition. CONCLUSIONS: Middermal elastolysis is probably more common than has been assumed so far. It does not affect nondermal elastic tissue. After progressive loss of dermal elasticity in a circumscribed area, a benign course follows, with a stable condition over several years. Electron microscopic findings indicate that elastic fiber phagocytosis is operative in the disappearance of the middermal elastic tissue.

Aged↗
PubMed1990

Muscle elasticity: effect of muscle length and temperature.

The present study describes a new method which allows the determination of muscle elasticity by applying quick releases at one end of a muscle and measuring the resulting tension drops at both ends, and simultaneously the propagation time of the mechanical impulse. The elasticity determined by both methods was examined on resting as well as on tetanized frog muscles (Rana esculenta, M. flexor hallucis brevis) in relation to muscle length and at two different temperatures 1 degree C and 20 degrees C. The average propagation velocity of the mechanical impulse of resting muscle was 55.7 +/- 4.7 m/s and of the contracting muscle 104.8 +/- 24.7 m/s at 1 degree C (L0, n = 6), which corresponds to elasticities of 3.3 +/- 0.5 N/mm2 and 14.4 +/- 6.2 N/mm2, respectively. The elasticity modulus calculated from the tension drop was for the resting muscle 2.3 +/- 0.5 N/mm2 and for the contracting muscle 11.1 +/- 2.1 N/mm2 (L0, 1 degree C, n = 6). When the muscle length is varied, the elasticity modulus corresponds to the length-tension relation of the resting and the isometrically contracting muscle. There is a strong correlation between the elasticity moduli which was determined by both methods for measurement of resting (r = 0.99, n = 19, p less than 0.05) and contracting muscle (r = 0.97, n = 19, p less than 0.05). This relation between elasticity and tetanic tension, i.e. filament overlap at constant temperature, can be interpreted in accordance with the sliding filament theory. But if the temperature is increased from 1 degree C to 20 degrees C, an increase of the tetanic tension (Q10 = 1.56) and a decrease of the elasticity measured by both methods (Q10 of 0.86 and 0.84) were obtained. This suggests that the increased tetanic force is generated by a smaller number of attached cross-bridges, but with a higher amount of force generated by each cross-bridge.

Animals↗
PubMed1989

Elastic fibers in the rat exorbital lacrimal gland duct system.

In the rat, each paired subcutaneous exorbital lacrimal gland overlies the retromandibular area. The fibrous cord containing its ducts passes over the masticatory muscles to the temporal canthus. Thus, the lacrimal system must accomodate both jaw and lid movements. To see whether elastic fibers exist to modulate alterations in tension caused by such movements, light and electron micrographs were made of its duct system. The innermost elastic fibers are connected by elaunin fibrils and oxytalan microfibrils to the lamina densa, particularly near the hemidesmosomes. The innermost elastic fibers appear to be longitudinal and about 0.2 micron from the lamina densa. Circumferential fibers exist about 0.8-3.2 microns from that structure. More peripheral fibers of both orientations also exist. Light microscopy of the extraglandular duct demonstrated circumferential fibers near the basement membrane and longitudinal and angular elastic fibers amid the collagenous layers. Some of the longitudinal fibers assume a loose cross-weave. Intraglandularly, as duct size diminishes elastic fibers progressively decrease in number and size until the smallest ducts have none. Thus, an elastic gradient exists. It is believed that recoil of the angular elastic fibers aids distension of the large and medium ducts when secretion is great and that recoil of the circumferential ones permits those duct diameters to diminish when secretion does. The longitudinal elastic fibers would allow all but the smallest ducts to recoil from the stretching of much of the exorbital lacrimal duct system accompanying blinking and other facial movements.

Animals↗
PubMed1995

Airway and lung elastic fibre is not reduced in asthma nor in asthmatics following corticosteroid treatment.

By morphometric investigation of the relative content of elastic and collagen fibres, we have tested the hypothesis that loss of elastic fibres in the conducting airways and lung parenchyma may reduce tissue elastic recoil, resulting in increased airway maximal closure and apparent increased responsiveness. The study groups comprised: Group A (n = 11) with relatively mild atopic asthma using inhaled bronchodilators prn (i.e. short-term corticosteroids users); Group B (n = 9) with more severe asthma requiring inhaled bronchodilators regularly, and daily inhaled glucocorticosteroids (i.e. longterm corticosteroid users); Group C (n = 12) normal healthy workers. Bronchial biopsy samples were taken from three sites from the left lung. Group A biopsy samples were taken before and after a 4 wk treatment period with inhaled corticosteroids (200 micrograms b.i.d.) and the relative elastic and collagen fibre content of a subepithelial zone was determined from electron micrographs. In a parallel study, the relative proportion of elastic fibre in post mortem lung tissue samples (inner aspect of the bronchial wall, alveolar wall, and points of attachment of surrounding alveoli to intrapulmonary bronchi) from subjects suffering a fatal asthma attack (n = 11), and non-asthmatic suffering sudden death (n = 9), were determined using Miller's elastic and eosin counterstain for light microscopy. In bronchial biopsies of normal subjects, 4.6 (SEM 1.1)% of subepithelial connective tissue was elastic fibre, similar to mild asthmatic subjects, 1.9 (SEM 0.48)%. Neither short-term (4 weeks) inhaled corticosteroid (200 micrograms b.i.d.) nor long-term (< 6 months) treatment with variable doses of inhaled steroids (100-1000 micrograms b.i.d.) significantly altered the elastic or collagen content of the tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗