DOES FAST EMBRYONIC BONE GROWTH TENSION THE PERIOSTEUM IN VIVO?

Currently, many children undergo precocious puberty, resulting in short stature due to premature closure of the growth plate. Pulsed electromagnetic field (PEMF) stimulation induces cell proliferation of articular chondrocytes. We developed a method for growth promotion using equipment with PEMF. In this study, we aimed to evaluate the effects of PEMF on the growth rate of growth plates using an animal model. An experimental study was conducted on 16 3-week-old rats to validate the effects of the growth care device on growth and development by PEMF stimulation at 28 Hz and 20 Gauss. The tibia bones of the groups with and without PEMF administration were dissected after 10 days, and then, the length of the growth plate of the knee and levels of insulin-like growth factor (IGF)-1 hormone in serum were measured. The length of the growth plate on the tibia bone and the levels of circulating IGF-1 were significantly increased by 25.6% and 13.6%, respectively, in the experimental group to which PEMF was applied compared to those of the control group, without any side effects. These results suggest that PEMF can safely stimulate growth of the growth plate in a non-invasive manner to promote bone growth.

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Rac signaling in osteoblastic cells is required for normal bone development but is dispensable for hematopoietic development

Blood ◽

10.1182/blood-2011-07-368753 ◽

2012 ◽

Vol 119 (3) ◽

pp. 736-744 ◽

Cited By ~ 16

Author(s):

Steven W. Lane ◽

Serena De Vita ◽

Kylie A. Alexander ◽

Ruchan Karaman ◽

Michael D. Milsom ◽

...

Keyword(s):

Bone Growth ◽

Bone Development ◽

Long Bone ◽

Perivascular Niche ◽

Hematopoietic Stem ◽

Hsc Niche ◽

Rac1 Gtpase

Abstract Hematopoietic stem cells (HSCs) interact with osteoblastic, stromal, and vascular components of the BM hematopoietic microenvironment (HM) that are required for the maintenance of long-term self-renewal in vivo. Osteoblasts have been reported to be a critical cell type making up the HSC niche in vivo. Rac1 GTPase has been implicated in adhesion, spreading, and differentiation of osteoblast cell lines and is critical for HSC engraftment and retention. Recent data suggest a differential role of GTPases in endosteal/osteoblastic versus perivascular niche function. However, whether Rac signaling pathways are also necessary in the cell-extrinsic control of HSC function within the HM has not been examined. In the present study, genetic and inducible models of Rac deletion were used to demonstrate that Rac depletion causes impaired proliferation and induction of apoptosis in the OP9 cell line and in primary BM stromal cells. Deletion of Rac proteins caused reduced trabecular and cortical long bone growth in vivo. Surprisingly, HSC function and maintenance of hematopoiesis in vivo was preserved despite these substantial cell-extrinsic changes. These data have implications for therapeutic strategies to target Rac signaling in HSC mobilization and in the treatment of leukemia and provide clarification to our evolving concepts of HSC-HM interactions.

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An Implanted Magnetic Microfluidic Pump for In Vivo Bone Remodeling Applications

Micromachines ◽

10.3390/mi11030300 ◽

2020 ◽

Vol 11 (3) ◽

pp. 300 ◽

Cited By ~ 2

Author(s):

Ziyu Chen ◽

Sunggi Noh ◽

Rhonda D. Prisby ◽

Jeong-Bong Lee

Keyword(s):

Bone Growth ◽

Static Pressure ◽

Dynamic Pressure ◽

The Body ◽

In Vivo Studies ◽

Fischer 344 ◽

Fischer 344 Rat ◽

Pressure Modulation

Modulations of fluid flow inside the bone intramedullary cavity has been found to stimulate bone cellular activities and augment bone growth. However, study on the efficacy of the fluid modulation has been limited to external syringe pumps connected to the bone intramedullary cavity through the skin tubing. We report an implantable magnetic microfluidic pump which is suitable for in vivo studies in rodents. A compact microfluidic pump (22 mm diameter, 5 mm in thickness) with NdFeB magnets was fabricated in polydimethylsiloxane (PDMS) using a set of stainless-steel molds. An external actuator with a larger magnet was used to wirelessly actuate the magnetic microfluidic pump. The characterization of the static pressure of the microfluidic pump as a function of size of magnets was assessed. The dynamic pressure of the pump was also characterized to estimate the output of the pump. The magnetic microfluidic pump was implanted into the back of a Fischer-344 rat and connected to the intramedullary cavity of the femur using a tube. On-demand wireless magnetic operation using an actuator outside of the body was found to induce pressure modulation of up to 38 mmHg inside the femoral intramedullary cavity of the rat.

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Osteogenic Potential Using a Malleable, Biodegradable Composite Added Traditional Chinese Medicine: in vitro and in vivo Evaluations

The American Journal of Chinese Medicine ◽

10.1142/s0192415x06004351 ◽

2006 ◽

Vol 34 (05) ◽

pp. 873-886 ◽

Cited By ~ 6

Author(s):

Chun-Hsu Yao ◽

Bai-Shuan Liu ◽

Chau-Guey Liu ◽

Yueh-Sheng Chen

Keyword(s):

Bone Substitute ◽

Bone Growth ◽

In Vitro Study ◽

Osteogenic Potential ◽

Calvarial Bone ◽

Large Defect ◽

Biodegradable Composite ◽

Calvarial Bone Defect

The purpose of this investigation was to prepare and evaluate the feasibility and biocompatibility of a new composite as a large defect bone substitute. The new GTGG was mainly composed of tricalcium phosphate ceramic particles and glutaraldehyde crosslinked gelatin in which Gui-Lu-Jiao was added (a mixture of Cervi Colla Cornus and Colla Plastri Testudinis). In the in vitro study, rat's calvaria osteoblasts were used to study bone characteristics upon exposure to different concentrations of the Gui-Lu-Jiao solution. In the in vivo study, GTGG composites were implanted into the defects of calvarial bones in mature New Zealand rabbits to test their osteogenerative characteristics. As a result, we found that Gui-Lu-Jiao added to the culture could promote the proliferation of osteoblasts. In addition, GTGG could induce a large amount of new bone growth in the rabbit's calvarial bone defect. Therefore, the GTGG composite might be a potential bone substitute.

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Recombinant human insulin-like growth factor: testing the somatomedin hypothesis in hypophysectomized rats

Journal of Endocrinology ◽

10.1677/joe.0.1120123 ◽

1987 ◽

Vol 112 (1) ◽

pp. 123-132 ◽

Cited By ~ 83

Author(s):

A. Skottner ◽

R. G. Clark ◽

I. C. A. F. Robinson ◽

L. Fryklund

Keyword(s):

Growth Factor ◽

Bone Growth ◽

Body Weight Gain ◽

Insulin Like Growth Factor ◽

Recombinant Human Insulin ◽

Poor Growth ◽

Igf I ◽

Hypophysectomized Rats ◽

Growth Promoting

ABSTRACT The in-vivo biological activity of recombinant methionyl insulin-like growth factor I (met-IGF-I) was demonstrated in hypophysectomized rats by following blood glucose after an i.v. bolus injection of met-IGF-I; a dose-dependent decrease in blood sugar was seen. Membrane transport was studied using the non-metabolizable amino acid α-aminoisobutyric acid; stimulation was obtained with the highest dose used (90 μg/rat). To test the original somatomedin hypothesis, growth studies were performed in hypophysectomized rats. Two or three doses of met-IGF-I were given with three different administration regimes (i.v. or s.c. infusion, or s.c. injections twice daily) for 6 or 8 days. Little growth-promoting activity was observed, with a significant effect on body weight gain obtained only when met-IGF-I was given continuously at the highest dose used (180 μg/day). No effect was seen on the in-vivo uptake of radioactive sulphate into cartilage. Epiphyseal cartilage width increased slightly at the highest dose of met-IGF-I, but only when the hormone was given by infusion. When 180 μg met-IGF-I/day were given by injections, a significant effect on longitudinal bone growth was obtained (90 μm above control). The levels of IGF in the serum were not measurably increased after s.c. administration of met-IGF-I, whereas after i.v. infusion, significantly raised levels were obtained at the higher dose rates (3·0 ± 0·3 and 2·8 ± 0·1 units/ml). Growth hormone was much more effective than met-IGF-I even at 50-fold lower doses. Priming the animals with 10 mu. bovine GH/day followed by combined infusions of GH and met-IGF-I did not reveal any potentiating effects of met-IGF-I in the presence of GH. We conclude that met-IGF-I is a relatively poor growth-promoting agent when given systemically, and that somatomedins are more likely to act as local growth factors rather than as circulating mediators of the growth-promoting effects of GH. J. Endocr. (1987) 112, 123–132

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Function of cGMP-Dependent Protein Kinases as Revealed by Gene Deletion

Physiological Reviews ◽

10.1152/physrev.00015.2005 ◽

2006 ◽

Vol 86 (1) ◽

pp. 1-23 ◽

Cited By ~ 273

Author(s):

F. Hofmann ◽

R. Feil ◽

T. Kleppisch ◽

J. Schlossmann

Keyword(s):

Protein Kinases ◽

Functional Data ◽

Bone Growth ◽

Muscle Relaxation ◽

Smooth Muscle Relaxation ◽

Biological Functions ◽

The Past ◽

Dependent Protein ◽

Water Secretion

Over the past few years, a wealth of biochemical and functional data have been gathered on mammalian cGMP-dependent protein kinases (cGKs). In mammals, three different kinases are encoded by two genes. Mutant and chimeric cGK proteins generated by molecular biology techniques yielded important biochemical knowledge, such as the function of the NH2-terminal domains of cGKI and cGKII, the identity of the cGMP-binding sites of cGKI, and the substrate specificity of the enzymes. Genetic approaches have proven especially useful for the analysis of the biological functions of cGKs. Recently, some of the in vivo targets and mechanisms leading to changes in neuronal adaptation, smooth muscle relaxation and growth, intestinal water secretion, bone growth, renin secretion, and other important functions have been identified. These data show that cGKs are signaling molecules involved in many biological functions.

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Poly(D,L-lactide/∊-Caprolactone)/Hydroxyapatite Composites as Bone Filler: An in Vivo Study in Rats

The International Journal of Artificial Organs ◽

10.1177/039139880202501209 ◽

2002 ◽

Vol 25 (12) ◽

pp. 1174-1179 ◽

Cited By ~ 20

Author(s):

A. şenköylü ◽

E. Ural ◽

K. Kesencì ◽

A. şìmşek ◽

ş. Ruacan ◽

...

Keyword(s):

Ring Opening ◽

Bone Growth ◽

Bone Defects ◽

Ring Opening Polymerization ◽

New Bone Formation ◽

The Third ◽

Bone Filler ◽

Green Polymer ◽

Animal Tests

In this study, a novel composite bone substitute was implanted in animal models (rats) and their in vivo characteristics were examined. A D,L-lactide and ∊-caprolactone copolymer (Mw: 80,000; Mn:40,000, and PI:2.00) was synthesized by ring-opening polymerization of the respective dimers using stannous octoate as the catalyst. The final ratio of D,L-lactide to ∊-caprolactone obtained by 1NMR was 60/40. Hydroxyapatite (HA) powder was loaded in the copolymer. The HA/copolymer ratio was 60/40 (w/w). These composites were easily shaped by hand. Animal tests were performed on mature wistar rats (n=30). Defects were created on the proximal, the thickest part of the femur. The bone defects of the first group were filled with polymer/HA composite, the second group filled with only HA and the third group was left empty. Histologic examination of bone tissues showed new bone formation around the yellow-green polymer/HA composite material in the first group of animals whereas no evidence of new bone growth was observed in other groups.

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Automated Segmentation and Object Classification of CT Images: Application toIn VivoMolecular Imaging of Avian Embryos

International Journal of Biomedical Imaging ◽

10.1155/2013/508474 ◽

2013 ◽

Vol 2013 ◽

pp. 1-10 ◽

Cited By ~ 4

Author(s):

Alexander Heidrich ◽

Jana Schmidt ◽

Johannes Zimmermann ◽

Hans Peter Saluz

Keyword(s):

Image Analysis ◽

Image Segmentation ◽

Bone Growth ◽

Imaging Techniques ◽

Long Bone ◽

Automated Segmentation ◽

Chick Embryos ◽

In Ovo

Background. Although chick embryogenesis has been studied extensively, there has been growing interest in the investigation of skeletogenesis. In addition to improved poultry health and minimized economic loss, a greater understanding of skeletal abnormalities can also have implications for human medicine. Truein vivostudies require noninvasive imaging techniques such as high-resolution microCT. However, the manual analysis of acquired images is both time consuming and subjective.Methods. We have developed a system for automated image segmentation that entails object-based image analysis followed by the classification of the extracted image objects. For image segmentation, a rule set was developed using Definiens image analysis software. The classification engine was implemented using the WEKA machine learning tool.Results. Our system reduces analysis time and observer bias while maintaining high accuracy. Applying the system to the quantification of long bone growth has allowed us to present the first truein ovodata for bone length growth recorded in the same chick embryos.Conclusions. The procedures developed represent an innovative approach for the automated segmentation, classification, quantification, and visualization of microCT images. MicroCT offers the possibility of performing longitudinal studies and thereby provides unique insights into the morpho- and embryogenesis of live chick embryos.

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