Organ and tissue level properties are more sensitive to age than osteocyte lacunar characteristics in rat cortical bone

Modeling and remodeling induce significant changes of bone structure and mechanical properties with age. Therefore, it is important to gain knowledge of the processes taking place in bone over time. The rat is a widely used animal model, where much data has been accumulated on age-related changes of bone on the organ and tissue level, whereas features on the nano- and micrometer scale are much less explored. We investigated the age-related development of organ and tissue level bone properties such as bone volume, bone mineral density, and load to fracture and correlated these with osteocyte lacunar properties in rat cortical bone. Femora of 14 to 42-week-old female Wistar rats were investigated using multiple complementary techniques including X-ray micro-computed tomography and biomechanical testing. The body weight, femoral length, aBMD, load to fracture, tissue volume, bone volume, and tissue density were found to increase rapidly with age at 14-30 weeks. At the age of 30-42 weeks, the growth rate appeared to decrease. However, no accompanying changes were found in osteocyte lacunar properties such as lacunar volume, ellipsoidal radii, lacunar stretch, lacunar oblateness, or lacunar orientation with animal age. Hence, the evolution of organ and tissue level properties with age in rat cortical bone is not accompanied by related changes in osteocyte lacunar properties. This suggests that bone microstructure and bone matrix material properties and not the geometric properties of the osteocyte lacunar network are main determinants of the properties of the bone on larger length scales

Modulation of aging process by diet and crosslinking inhibitor and their effects on production in poultry

The factors which influence the age-related decline in production performance and increases in meat toughness in broiler breeder hens are poorly understood. We have hypothesized that the elevated plasma concentration of glucose contributes to the nonenzymatic attachment of glucose to proteins, and generates glycoxidation crosslinks in tissues which can ultimately impair function, is responsible for loss of production. One such crosslink, pentosidine, is an established indicator of both glycative and oxidative tissue damage in mammals. Specifically, the role of diet restriction (DR) and a nucleophilic hydrazine compound, aminoguanidine (AG), a crosslinking inhibitor, were examined on tissue crosslinking with the view towards both extending the production period and improving carcass quality of broiler breeder hens. Additionally, isolation of pentosidine from skin and tendons of hens and their relationship with tendon breaking strength (TBS), time (TBT) and meat tenderness (SF) were carried out. Chicks were randomly divided into four dietary groups from eight to 125 wks after hatch: ad libitum (AL); diet restricted (DR, fed 60% of ad libitum ); AL and DR groups supplemented with 400 ppm AG (1.35 mg/kg BW/day) each (AL+ AG and DR+AG respectively).;The results showed that pentosidine was present in the skin (Ps ) and tendon (Pt) of the broiler breeder hens, and that there was an age-related, linear increase in its concentration (p\u3c0.001, r2=0.94) for skin and (p\u3c0.0001; r2=0.79) for tendon in AL-fed hens. DR and supplementation of AG with AL-fed hens (AL+AG) retarded Ps (p\u3c0.001; p\u3c0.001) and Pt (p\u3c0.001; p\u3c0.01) respectively as compared to AL-fed hens. Concurrently, there was also an age-related parallel increase in TBS ( p\u3c0.0001; r2=0.56), in TBT ( p\u3c0.0001; r2=0.67), and in shear force (SF) (p\u3c0.0001; r2=0.95) in AL-fed hens. Similarly DR significantly retarded the overall TBS ( p\u3c0.01) TBT (p\u3c0.02), and SF (p\u3c0.0001) values as compared to AL-fed hens over the period of this study. Supplementation of AL-fed hens with AG (AL+AG group) significantly retarded the concentration of Pt, Ps and SF values and was similar to those of the t s DR group. Although, supplementation of DR with AG (DR+AG) retarded the rate of accumulation of Ps (p\u3c0.001) over the laying cycle, the reduction in Ps did not significantly affect s s the mean production. It is therefore concluded that the rate of P s and Pt accumulation and the s t age-related increase in meat toughness can be retarded by either DR or AG. Ps can also be used s as a predicator of age-related changes in meat. The same approach has the potential to be initiated in other animal production systems. Because of the linear, age-related increase in the concentrations of tissue pentosidine, it can be used as biomarker for the study of aging

Mechanics of nonlinear biomembranes: application to ophthalmology

Changes in the mechanics of the lens capsule of the eye arising from alterations of its native configuration can lead to undesirable clinical results. One example is the surgical introduction of a hole into the lens capsule and subsequent removal of the cloudy lens during cataract surgery. The adverse effect is secondary cataract on the posterior lens capsule, brought about by a sudden proliferation of lens epithelial cells in the region. Understanding the biomechanics of the anterior lens capsule is necessary in order to model its behavior under various physiological conditions and predict its response to alterations and perturbations such as those during cataract surgery. Such knowledge will help in the improvement of techniques during cataract surgery, and in the design of artificial intraocular lens. In this study we present, for the first time, results that demonstrate that the anterior lens capsule exhibits non-homogeneity and regionally varying anisotropy. We also compute stresses in the lens capsule due to normal loading conditions and procedures such as a capsulorhexis

FEMTO-LASER-ASSISTED SURGERY OF CONGENITAL CATARACT IN CHILDREN

Background. The qualitative anterior capsulorhexis in cataract surgery in children with intraocular lens implantation is an important and crucial moment. Difficulties in carrying out capsulorhexis arise from the structural features of the lens capsule at this age. A search of new methods of the capsulorhexis formation in congenital cataract surgery with a more predictable result is an actual problem.Purpose. To study an effectiveness and a safety of the femtosecond laser in cataract surgery in children.Material and methods. The study was conducted in 29 children (30 eyes) with congenital cataracts aged from 2 to 6 years. In the group I the femtolaser capsulorhexis followed by aspiration-irrigation and IOL implantation was used in 14 children (15 eyes). In the group II, 15 children (15 eyes) underwent the manual circular continuous capsulorhexis followed by aspiration-irrigation of congenital cataract and lens implantation. The uncorrected visual acuity (UCVA) preoperatively in both (I and II) groups averaged 0.03±0.01 and 0.08±0.01, respectively.Results. In patients of the group I the femtolaser stage was unremarkable. Single subconjunctival microhemorrages were observed in 46.6% of the cases in the contact area of the vacuum ring. In 4 (26.6%) eyes after femtosecond capsulotomy a constriction of the pupil was observed.A centered anterior capsulorhexis of perfect round shape was obtained in all patients of the group I. In assessing the capsulorhexis diameter a slight increase around 100-200 microns was found intraoperatively. Single bridges that did not affect the shape, location and size of the capsulotomy were revealed during the removal of capsular flap in one case. During the manual capsulorhexis there was a tendency to runaway without going to the posterior capsule and the formation of a slightly decentered and oval capsulorhexis in patients of group II in 7 cases. Improvement of visual acuity was noted on the first day after surgery in both groups (p<0.001). The UCVA in the groups I and II on the first day after surgery was 0.3±0.04 and 0.1±0.05, respectively.Conclusions. Automated capsulorhexis with a femtosecond laser in congenital cataract surgery in children allows to exclude technical accuracy errors of this procedure and to obtain a optimal capsular fixation of the IOL, making the procedure technique more safe

Physiologic and therapeutic roles of somatotropin effects in adult animals

12/94.Includes bibliographical references (pages 11-12)

Characterisation and Modelling of an Artificial Lens Capsule Mimicking Accommodation of Human Eyes

A synthetic material of silicone rubber was used to construct an artificial lens capsule (ALC) in order to replicate the biomechanical behaviour of human lens capsule. The silicone rubber was characterised by monotonic and cyclic mechanical tests to reveal its hyper-elastic behaviour under uniaxial tension and simple shear as well as the rate independence. A hyper-elastic constitutive model was calibrated by the testing data and incorporated into finite element analysis (FEA). An experimental setup to simulate eye focusing (accommodation) of ALC was performed to validate the FEA model by evaluating the shape change and reaction force. The characterisation and modelling approach provided an insight into the intrinsic behaviour of materials, addressing the inflating pressure and effective stretch of ALC under the focusing process. The proposed methodology offers a virtual testing environment mimicking human capsules for the variability of dimension and stiffness, which will facilitate the verification of new ophthalmic prototype such as accommodating intraocular lenses (AIOLs)

Etablierung eines In-vivo-Modells zur molekularbiologischen Untersuchung von Stoffwechselmarkern bei der Knochenregeneration unter intermittierender Parathormongabe

In der vorliegenden Studie wurde an weiblichen Ratten mittels Knochenkammer-Modell und PCR-Analyse die Expression der Knochenmarker RANK, RANKL und OPG unter intermittierender PTH-Applikation (60 µg /kg KG) im periimplantären Knochen untersucht. Es zeigte sich ein niedriges Expressionsniveau nach 21 Tagen. Im Rahmen einer Expressionssteigerung nach 42 Tagen lag das Expressionslevel von RANK und RANKL unterhalb und das von OPG oberhalb dessen der unbehandelten Kontrolle. Ein signifikanter Unterschied zwischen der PTH- und der NaCl-Applikation bestand nur bei der RANK-Expression

Abordagens farmacológicas para melhorar a cicatrização óssea

Com a evolução tecnológica e médica, verificou-se um aumento de fraturas ósseas por acidentes de viação e fraturas relacionadas com a idade. Dado o impacto significativo desta patologia a nível económico e social, e sabendo que 5 a 10% das fraturas ósseas apresentam complicações na cicatrização, é relevante o estudo de potenciais métodos que melhorem o tratamento e reduzam o impacto socioeconómico destas. Foi realizada uma pesquisa na plataforma PUBMED usando palavras-chave como: "regeneração óssea", "agentes anti-reabsortivos", "agentes anabólicos", "medicamentos anti-osteoporóticos", entre outras, tendo sido analisados estudos pré-clinicos, estudos clínicos, revisões sistemáticas e meta-análises de forma a reunir o conhecimento farmacológico mais relevante neste contexto. Foi analisada a evidência alusiva aos fármacos usados no tratamento da osteoporose, o seu impacto na regeneração óssea e possíveis alterações necessárias à terapêutica em doentes pós fratura. É analisado também, o uso neste contexto dos inibidores da fosfodiesterase 5 e estatinas, que podem, de forma "off-label" melhorar a regeneração óssea, assim como novos tratamentos direcionados para à fratura óssea com o dasatinib e o Ácido Salviânico A que demonstraram resultados em modelos animais.With the evolution of medicine and technology, there has been an increase in bone fractures related to car accidents and bone fractures related to age. Given the meaningful impact this pathology has on a social and economic level, knowing that 5 to 10% of bone fractures end up with complications in regeneration, it is relevant to study the potential ways to enhance treatment and decrease the social and economic impact. A literature review was performed in PUBMED using key-words such as "fracture healing", "anti-resorptive drugs", "anabolic agents", "anti-osteoporotic drugs", "enhancing factors", and others and analyzing pre-clinical studies, clinical studies, systematic reviews and meta-analysis as a way to reunite the most important knowledge in this field. The evidence concerning the pharmacological treatment of osteoporosis, its impact on bone regeneration and post-fracture therapeutic schemes was analysed. The «off-label« use of phosphodiesterase 5 inhibitors and statins in this context was considered, as well as new directed treatments like the targeting of dasatinib and the targeting of Salvianic acid A-loaded bone targeting liposome (SAA-BTL) to bone fracture sites