Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Polypropylenes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5Linked to original sources
PubMed2004

A three centre study of the variability of ankle foot orthoses due to fabrication and grade of polypropylene.

This study investigates if fabrication techniques employed at different orthotic centres affect the characteristics of the manufactured plastic orthoses. Plaster models were formed from the same master mould. The thickness and bending stiffness of the supplied polypropylene sheets were measured prior to fabrication. An orthotic technician at each of the 3 orthotic centres manufactured 4 homopolymer and 4 copolymer polypropylene ankle-foot orthoses (AFOs), following each centre's fabrication practice. Another technician at one of the orthotic centres manufactured an additional 4 homopolymer and 4 copolymer AFOs. The thickness, the dorsiflexion stiffness and plantarflexion stiffness of the 32 fabricated AFOs were monitored and compared. Analysis of the results suggests: Copolymer polypropylene sheets are supplied marginally thicker than homopolymer polypropylene sheets. The difference between the thickness of the 16 copolymer and 16 homopolymer AFOs was not significant. The thickness of the AFOs manufactured in copolymer was less consistent than homopolymer. Dorsiflexion stiffness of the copolymer AFOs was less consistent than homopolymer AFOs. Although the bending stiffness of the copolymer and homopolymer sheets differed significantly, there was no significant difference between the dorsiflexion stiffness of the copolymer and homopolymer AFOs. Plantarflexion stiffness was consistent for both the copolymer and the homopolymer AFOs and there was no significant difference between the plantarflexion stiffness of the copolymer and homopolymer AFOs. The thickness and flexural stiffness of the AFOs manufactured by 2 technicians at the same centre did not differ. These results are useful benchmarks for the flexural stiffness of AFOs.

Ankle↗
PubMed1999

Autologous skin graft, human dura mater and polypropylene mesh for the repair of ventral abdominal hernias: an experimental study.

OBJECTIVE: To compare primary repair and grafting with one of two materials (one biological human dura mater, and one synthetic polypropylene mesh) or autologous skin, with primary repair alone in abdominal wall hernias in rats. DESIGN: Randomised experiment. SETTING: Teaching hospital, Turkey. ANIMALS: 72 male Wistar albino rats randomised into 4 groups of 18 rats each. These were further randomly divided into subgroups of 6 each that were killed on days 15, 30,and 45 postoperatively. INTERVENTIONS: Each test material was sutured to the abdominal wall by an onlay technique. MAIN OUTCOME MEASURES: Macroscopic and microscopic appearance, and strength of the abdominal wall. RESULTS: Macroscopically, dura mater grafts lost their original shape, but polypropylene and skin did not. When completely incorporated the skin grafts had developed a new fascia. Dura mater and polypropylene induced a pronounced inflammatory reaction at all three times postoperatively, and there were significantly more fibroblasts in the dura mater group on days 15 and 30, and in the skin graft group on day 45, than in the other groups (p < 0.05). Mechanical resistance and mean breaking strength were significantly greater in the skin graft group than in the other groups at all times tested (p < 0.05). CONCLUSION: Full thickness autologous skin grafts were stronger than both human dura mater and polypropylene mesh when used to reinforce primary repairs of abdominal wall hernias in rats.

Animals↗
PubMed2000

Loss of THCCOOH from urine specimens stored in polypropylene and polyethylene containers at different temperatures.

The loss of delta9-tetrahydrocannabinol (THCCOOH) from urine specimens stored in polypropylene and polyethylene containers at 4 degrees C and 25 degrees C was examined. All specimens were analyzed by GC-MS after sampling at various times over a one-week period. Data were analyzed by one-way analysis of variance and fitted with a first order kinetic equation. Rapid loss of THCCOOH was seen at 4 degrees C for both polypropylene (14% maximal loss, t(1/2) = 0.53 min) and polyethylene (17% maximal loss, t(1/2) = 5.77 min) bottles. At 25 degrees C, a small loss (< 5%) was observed in polypropylene and no significant loss was seen for urine in polyethylene. All losses stabilized within 1 h, and no further losses were seen over one week. The results indicate that THCCOOH binding may be due to decreased solubility of THCCOOH at lower temperatures and subsequent association of THCCOOH with the more lipophilic plastic. The results also indicate that polypropylene and polyethylene do not bind THCCOOH to such an extent as to compromise the integrity of specimens.

Dronabinol↗
PubMedDate not supplied

Comparison of the in vivo behavior of polyvinylidene fluoride and polypropylene sutures used in vascular surgery.

To find a nonabsorbable suture material that is equivalent to polypropylene in ease of handling and tensile properties, and that has low thrombogenicity and tissue reactivity but improved biostability, some researchers and clinicians see merit in considering the suitability of monofilaments made from polyvinylidene fluoride. The current animal study investigated the relative biocompatibility and biostability of these two suture materials by using them to anastomose a polyester arterial prosthesis in a canine thoracoabdominal bypass model for 10 periods of implantation ranging from 4 hr to 2 years. Biocompatibility was assessed with light and scanning electron microscope examinations of the explanted sutures, and biostability of the cleaned sutures was determined by Fourier transform infrared spectroscopy and scanning electron microscope analysis. The polyvinylidene fluoride and polypropylene sutures were found to have similar handling and healing characteristics. During the first months in vivo, both types of suture experienced a temporary increase in carbonyl group absorption that coincided with the duration of the inflammatory response. After 1 and 2 years in vivo, the explanted polypropylene sutures showed visual evidence of surface stress cracking. This was not found with the explanted polyvinylidene fluoride sutures. These results suggest that polyvinylidene fluoride may be more biostable than polypropylene in the long term.

Animals↗
PubMedDate not supplied

Comparison of stainless steel fascial staples and polypropylene suture material for closure of the linea alba in dogs.

Five centimeter segments of the linea alba in mature, female, mixed breed dogs were incised and then approximated with either stainless steel fascial staples or size 0 polypropylene suture material. Breaking strength of the linea alba closures was determined at 0 (Phase I, 18 dogs) and at 7, 14, and 31 days (Phase II, 18 dogs). Histology and videointeractive planar morphometry were used to evaluate healing of the linea alba. Breaking strength and histologic and morphometric variables were analyzed statistically using analysis of variance in a split plot design. In a clinical trial, 20 cm linea alba incisions were approximated with stainless steel fascial staples after elective ovariohysterectomy in mature, female, mixed breed dogs (Phase III, eight dogs). The dogs were evaluated at 1, 2, 7, 14, 31, 90, and 180 days. Linea alba incisions approximated with polypropylene suture material were significantly stronger than linea alba incisions approximated with stainless steel fascial staples on day 0. There was no significant difference between breaking strength values, histologic, and morphometric appearance of linea alba incisions closed with stainless steel fascial staples or polypropylene suture material when compared 7, 14, and 31 days after surgery. All of the dogs in the clinical trial appeared to be normal at all evaluation times. Approximation of linea alba incisions with stainless steel fascial staples compares favorably to closure with a simple continuous pattern of polypropylene suture material with regard to breaking strength, clinical, histologic, and morphometric appearance.

Abdominal Muscles↗
PubMed1994

Polypropylene production workers and colorectal cancer in Germany: a brief report.

OBJECTIVE: A retrospective cohort study of 640 male polypropylene production workers in Germany was performed to evaluate the reported association between colorectal cancer and polypropylene. METHOD: The follow up period was 1956 to 1990. Expected numbers of cancers were derived from incidence rates adjusted for age and calendar year from the Saarland cancer registry. RESULTS: Three colorectal cancers were identified compared with 4.0 expected (standardised incidence ration (SIR) = 0.75, 95% confidence interval (95% CI): 0.15-2.19). For total cancers there were 27 cases in the cohort compared with 35.4 expected (SIR = 0.76, 95% CI: 0.50-1.11). DISCUSSION: These results do not support earlier reports of a link between polypropylene production and colorectal cancer, but are consistent with a number of recent investigations of polypropylene production workers that have reported no association with risk of colorectal cancer. Due to the small size of this and other similar studies, however, a small to moderate increase in risk cannot be ruled out.

Cohort Studies↗
PubMed2005

The argument for lightweight polypropylene mesh in hernia repair.

The development of polypropylene prosthetics revolutionized surgery for the repair of abdominal wall hernias. A tension-free mesh technique has drastically reduced recurrence rates for all hernias compared to tissue repairs and has made it possible to reconstruct large ventral defects that were previously irreparable. The repair of abdominal wall defects is one of the most commonly performed general surgical procedures, with over 1 million polypropylene implants inserted each year. Surprisingly, little research has been performed to investigate the interaction of abdominal wall forces on a ventral hernia repair or the required amount or strength of the foreign-body material necessary for an adequate hernia repair. The long-term consequences of implantable polypropylene prosthetics are not without concern. The body generates an intense inflammatory response to the prosthetic that results in scar plate formation, increased stiffness of the abdominal wall, and shrinkage of the biomaterial. Reducing the density of polypropylene and creating a ''light weight'' mesh theoretically induces less foreign-body response, results in improved abdominal wall compliance, causes less contraction or shrinkage of the mesh, and allows for better tissue incorporation. A review of the laboratory data and short-term clinical follow-up is reviewed to provide a strong basis or argument for the use of ''light weight'' prosthetics in hernia surgery.

Dioxanes↗
PubMed2005

[Evaluation of postoperative adhesions in rats submitted to peritoneostomy with polypropylene mesh associated to nitrofurazone].

BACKGROUND: Peritoneal injuries, common in per and postoperative, lead to the formation of adhesions. The use of polypropylene mesh increases the postoperative adhesions incidence. Based on the fact of nitrofurazone accelerates the healing process, a possible action on peritoneal adhesions was cogitated. AIM: To evaluate postoperative adhesions in rats submitted to peritoneostomy with polypropylene mesh fixation associated to nitrofurazone. METHODS: Thirty-three Wistar rats were separated into three groups of eleven animals each one. In group I was performed the laparotomy with exposition of the abdominal cavity followed by the laparotomy suture; in group II was performed the resection of a abdominal wall fragment followed by polypropylene mesh fixation on the gap and in group III was performed the same done in group II, but the mesh was previously impregnated with nitrofurazone. After 45 days the animals were sacrificed and necropsied. RESULTS: Seven animals of group I had no adhesions (degree 0), two had degree 1 adhesions and two had degree 2. In group II, one animal was classificated as degree 3 and ten as degree 4. In group III, one had degree 0, eight had degree 3 and one had degree 4 (one animal died before 45 days). All adhesions found involved the abdominal wall; ten animals had adhesions involving only omentum (group I = 4; group II = 1 and group III = 5); eleven animals had adhesions involving omentum, small bowel and other abdominal organs (group II = 10; group III = 1); three animals had adhesions involving only small bowel, all belonged to group III. Fourteen animals had adhesions involving small bowel, of these ten belonged to group II (nine with more than one fixation point) and four belonged to group III (three with just one fixation point). CONCLUSION: The association of nitrofurazone with polypropylene mesh did not reduce significantly the postoperative adhesions incidence in rats, but reduced the intensity and severity of these adhesions.

Animals↗
PubMedDate not supplied

[Expanded polytetrafluoroethylene and polypropylene in the repairing of abdominal wall defects in Wistar rats. Comparative study].

PURPOSE: To compare the use of polypropylene and PTFE meshes in the treatment of incisional hernias made experimentally on Wistar rats. METHODS: The experiment used 24 Wistar rats divided into three cohorts: C-A (ressection of a segment of abdominal wall), E-A (ressection and placement of PTFEe mesh), E-B (resection and placement of polypropylene mesh). After 28 days, the mesh and the surrounding tissue were removed and submitted to macroscopic analysis (assessment of the abdominal wall for presence of abscess in the surgical wound and/or skin necrosis, and adhesions) as well as microscopic analysis (presence of fibrosis, necrosis and abscess, counting of macrophages, mononuclears and polymorphonuclears). RESULTS: Adhesions and abscesses in the surgical wound were observed more commonly associated to the group treated with PTFEe. The size of the fibrous tissue was greater in the group treated with polypropylene. Cohort E-A showed PTFEe mesh enveloped by organized fine connective tissue. No groups presented necrosis on the site of the insertion. The highest mononuclear inflammatory reaction occurred in association to PTFEe when compared to the control group, but the findings for the polypropylene mesh were also significant when compared to the control group. In the analysis of the results obtained for cohorts E-A and E-B, a minimal occurrence of polymorphonuclears was noticed in both groups, which indicates low tissue reactivity to both materials used in the present experiment. CONCLUSION: Even with epithelization and proliferation of connective tissue, anchorage between PTFEe and abdominal wall is insufficient, which can result in reherniations.

Abdominal Wall↗
PubMedDate not supplied

FTIR-ATR spectra of protein A immobilized on to functionalized polypropylene membranes by gaseous plasma of oxygen and of anhydrous ammonia.

Polypropylene membranes were treated in a gaseous plasma of oxygen or anhydrous ammonia, in order to add hydroxyl groups (oxygen plasma) or amino groups (ammonia plasma) on their surfaces. The presence of these functional groups was detected by FTIR-ATR spectrometry. The FTIR-ATR spectrum of free Protein A was recorded and absorption bands for amide I and amide II at 1650 cm-1 and 1552 cm-1 were identified. The surfaces of immobilized Protein A on to hydroxylated polypropylene membranes and on to polypropylene membranes having amino groups, were characterized by FTIR-ATR spectrometry. The presence of amide I and amide II absorption bands confirmed the immobilization of Protein A on to functionalized polypropylene membranes by gaseous plasma modification.

Ammonia↗
PubMed1999

Prevention of adhesion formation with use of sodium hyaluronate-based bioresorbable membrane in a rat model of ventral hernia repair with polypropylene mesh--a randomized, controlled study.

BACKGROUND: There is a high incidence of adhesions after ventral hernia repair with polypropylene mesh. Hyaluronic acid (HA)-based membrane has been shown to reduce the incidence of adhesions in the absence of prosthetic mesh. The purpose of this study was to determine the effect of HA membrane on the quantity and grade of adhesions and its effect on strength of repair after abdominal wall repair with polypropylene mesh. METHODS: In 61 rats a full-thickness abdominal wall defect (excluding skin) was created, and a section of small bowel was abraded. The animals were randomized, receiving either HA membrane to cover the viscera or no membrane. The fascial defect was repaired with polypropylene mesh. Equal numbers of animals from each group were killed at 4 weeks and 8 weeks after surgery. Adhesion severity and percentage of mesh surface covered with adhesions were estimated. Tensile strength between mesh and muscle from each animal was measured. Sections of the mesh-muscle interface were examined histologically and measured for thickness and graded for inflammation and fibrosis. RESULTS: Fifty-five animals survived until the end point. Animals in the HA membrane group had a significant reduction in (1) grade of adhesions between small bowel and mesh at 4 weeks (P = .009) and 8 weeks (P = .000001), (2) grade of adhesions between colon and mesh at 8 weeks (P = .00003), and (3) percentage of mesh covered with adhesions at 4 weeks (P = .01) and 8 weeks (P = .0000002). There was no difference between the 2 groups in tensile strength of the repairs, tissue thickness, degree of inflammation, or degree of fibrosis. CONCLUSIONS: HA membrane reduces the quantity and grade of adhesions of both small and large bowel, to polypropylene mesh in a rat model of ventral hernia repair, without compromising strength of the repair.

Animals↗
PubMedDate not supplied

Endophthalmitis after cataract surgery in eyes with small pupils managed by sector iridectomy and polypropylene suture closure.

Two patients with small pupils developed endophthalmitis following cataract surgery during which the small pupils were managed by sector iridectomy and closed with a polypropylene suture. Prior studies have reported that implantation of intraocular lenses (IOLs) with haptics made of polypropylene is associated with a higher risk of postoperative endophthalmitis than the use of IOLs with polymethylmethacrylate haptics. Endophthalmitis in the two patients reported herein was managed successfully without removal of the polypropylene suture; vision returned to 20/60 in one patient and 20/30 in the other patient. Iris retractors may represent a faster and safer alternative management option for small pupils than sector iridectomy closed with a polypropylene suture.

Aged↗
PubMed2001

Incisional hernia and its repair with polypropylene mesh in renal transplant recipients.

PURPOSE: We evaluate the incidence of incisional hernia after kidney transplantation, predisposing factors and the results of surgical repair with polypropylene mesh. MATERIALS AND METHODS: We reviewed the records of 371 consecutive kidney transplants performed between April 1995 and February 2000. Patients with clinical signs of hernia at the transplant incision site were included in the study. Predisposing factors for incisional hernia were also reviewed. A prospective protocol of surgical correction was established using polypropylene mesh and patient outcome was studied. RESULTS: We identified 14 patients (3.8%) with an incisional hernia at the transplant incision site. Hernias developed 3 to 840 days after transplant surgery and were significantly more common in white (p = 0.019) and cadaveric graft (p = 0.02) recipients. Predisposing factors in 11 cases included complications of transplant surgery in 7, bladder obstruction in 2, large polycystic kidneys in 1 and chronic pulmonary disease in 1. Surgical repair was performed by primary fascial approximation and polypropylene mesh reinforcement in 13 cases and by pre-peritoneal mesh placement in 1. Minor subcutaneous wound infection developed in 1 patient. No relapses were noted at a mean followup of 17.8 months. CONCLUSIONS: In the majority of cases incisional hernia develops in the first 3 months after transplant surgery. The incidence is significantly higher in white patients and after cadaveric donor transplantation. Surgical complications of transplant surgery are important predisposing factors for incisional hernia after kidney transplantation. Surgical repair using polypropylene mesh is safe and effective in this group of patients.

Adult↗
PubMed2002

Polypropylene mesh tape for stress urinary incontinence: complications of urethral erosion and outlet obstruction.

PURPOSE: Gynecare tension-free vaginal tape (Ethicon, Inc., New Brunswick, New Jersey) is a propylene mesh tape recently introduced in the United States as minimally invasive treatment for stress urinary incontinence. We report the combined experience at 3 tertiary care institutions with graft erosion and bladder outlet obstruction after procedures performed elsewhere. MATERIALS AND METHODS: We reviewed the records of 5 patients with complications who presented to 1 of 3 institutions after polypropylene mesh tape placement. All pertinent information was obtained from the medical records and the operating surgeon at the referring institution. RESULTS: Treatment was required in 2 patients with urethral erosion, 1 with vaginal and bladder erosion, and 2 with bladder outlet obstruction. Common presenting symptoms included urge, urge incontinence and gross hematuria. Cystoscopy showed polypropylene graft erosion at the urethra or through the bladder wall. Each patient required explantation of the polypropylene mesh tape and further surgery to restore continence. The graft was divided transvaginally in the 2 patients presenting with outlet obstruction. Urge incontinence resolved and they returned to complete spontaneous voiding. CONCLUSIONS: High clinical suspicion is necessary when evaluating patients presenting with urinary symptoms after polypropylene mesh tape placement. Bladder outlet obstruction and possible graft erosion should be considered.

Adult↗
PubMed2003

Prospective randomized, double-blind, controlled trial comparing Lichtenstein's repair of inguinal hernia with polypropylene mesh versus Surgisis gold soft tissue graft: preliminary results.

INTRODUCTION: Although polypropylene mesh are the preferred prosthesis materials for the tension-free hernioplasties because they handle well and become quickly integrated, having reduced the recurrence rate below 1%, some problems with their use are still to be addressed (postoperative pain, long-term discomfort, infections, intestinal obstruction and fistulization). In order to answer to these disadvantages, a new degradable and reabsorbable material, the porcine small intestinal submucosa (SIS mesh gold, Surgisis), has recently been used in humans for laparoscopic hernia repairs. Aim to our study is to evaluate the safety and efficacy of the Lichtenstein's hernioplasty using the Surgisis gold soft tissue graft, as a mesh, and to compare it with the traditional Lichtenstein procedure performed with polypropylene mesh. METHODS: A prospective, randomised, double-blinded comparison of Lichtenstein's repair of inguinal hernia with polypropylene mesh versus Surgisis ES soft tissue graft was carried out at the Department of Emergency Surgery of St Orsola-Malpighi University Hospital with the participation of 4 surgeons who accept to standardise the Lichtenstein's procedures with the two different types of meshes. RESULTS: From july 2002 up to now 20 patients submitted to Lichtenstein's repair of inguinal hernia using Surgisis gold mesh with a 6 month minimum follow-up were enrolled. 12 subjects were treated with Surgisis ES mesh, while 8 were treated polypropylene mesh. There were not intraoperative or postoperatively complications. No recurrences and wound infections were observed. The post-hernioplasty acute and chronic pain/discomfort (tested with visual analogue scale and simple verbal scale) and parenteral/oral analgesic consumption were lower in Surgisis ES group. CONCLUSIONS: Lichtenstein's hernioplasty using the Surgisis gold soft tissue graft has a promising safety and efficacy.

Adult↗
PubMedDate not supplied

Adhesion formation after laparoscopic ventral incisional hernia repair with polypropylene mesh: a study using abdominal ultrasound.

OBJECTIVE: Laparoscopic repair of ventral incisional hernias is feasible and safe. Polypropylene mesh is often preferred because of its ease of handling and lower cost. Complications like adhesion and fistula formation can occur. The goal of this study was to determine whether bowel adhesions and their attendant complications could be prevented by interposition of omentum. METHODS: Thirty patients underwent laparoscopic ventral incisional hernias repair with polypropylene mesh. Omentum was always positioned over the loops of bowel for protection. At a mean follow-up of 14 months, 20 patients underwent ultrasonic examination using the previously described visceral slide technique to detect adhesions. RESULTS: The mean size of the hernias in the study was 50.3 cm2, and the mean size of the mesh applied was 275 cm2. Thirteen patents (65%) had no sonographically detectable adhesions. Five patients demonstrated adhesions between the mesh and omentum, 1 patient developed adhesions between the left lobe of the liver and the mesh, and only 1 case of bowel adhesion to the edge of the mesh was found. CONCLUSION: Laparoscopic ventral incisional hernias repair with polypropylene mesh and omental interposition is not associated with visceral adhesions in the majority of patients. Polypropylene mesh can be used safely when adequate omental coverage is available.

Adult↗
PubMed2004

[Experimental study of a polypropylene mesh for moulding and supporting a breast during a breast reduction procedure].

OBJECTIVE: To study the polypropylene mesh acted for the moulding and support. METHODS: Four mini-pigs were used in this experimental research. A polypropylene mesh was implanted under the skin on one side of each pig. An expander was thereafter placed in the deep layer to imitate the action of gravity to the skin and mesh. The specimens were collected in two different times for the biomechanics and histology examinations. RESULTS: The biomechanical data were shown lower and the histological properties were found changeable in the expanded skin without the mesh support, compared with the normal skin. However, the changes did not occur in the expanded skin with the mesh support. Furthermore, the tensile strength and elastic modulus of the polypropylene mesh were significant less than the human skin. CONCLUSION: The Polypropylene mesh could prevent the extended skin effectively and has moulding and support effects.

Animals↗
PubMed2005

Tension-free polypropylene mesh for vaginal repair of anterior vaginal wall prolapse.

OBJECTIVE: To study the ongoing results of the repair of anterior vaginal wall prolapse reinforced with tension-free polypropylene mesh (GyneMesh, Gynecare, Ethicon, Issy-Les-Moulineaux, France). STUDY DESIGN: A case series of 87 consecutive women with anterior vaginal wall prolapse who underwent a transvaginal procedure using polypropylene mesh between October 1999 and August 2002. The mean age (+/-SD) was 62.4+/-13.4 years. Before the operation, patients underwent physical examination staging of the prolapse with the International Pelvic Organ Prolapse staging system. Thirteen women had stage 2 anterior vaginal wall prolapse (14.9%), 59 had stage 3 (67.9%), and 15 had stage 4 (17.3%). The polypropylene mesh was placed from the retropubic space to the inferior part of the bladder in a tension-freefashion. Patients were followed for 9-43 months, with a median follow-up (+/-SD) of 24+/-9.6 months. We defined "cure" as satisfactory (stage 1) or optimal (stage 0) outcome for point Ba in the staging system. RESULTS: Eighty-four patients returned for follow-up (96.6%). At follow-up, 77 women were cured (91.6%), 5 women had asymptomatic stage 2 anterior vaginal wall prolapse, and 2 had a recurrent stage 3 (2.4%). There were no postoperative infections. There were a total of 7 vaginal erosions of the mesh (8.3%); 4 necessitated a second procedure for partial excision of the mesh. CONCLUSION: Vaginal repair of anterior vaginal wall prolapse reinforced with tension-free polypropylene mesh is effective and relatively safe. Vaginal erosion occurred in 8.3% of the study population but was easily manageable, with no sequelae.

Age Distribution↗