Delta like 1 (DLK1) has been proposed to act as a regulator of cell fate determination and is linked to the development of various tissues including skeletal muscle. Herein we further investigated DLK1 expression during skeletal muscle remodeling. Although practically absent in normal adult muscle, DLK1 was upregulated in all human myopathies analyzed, including Duchenne-and Becker muscular dystrophies. Substantial numbers of DLK1 1 satellite cells were observed in normal neonatal and Duchenne muscle, and furthermore, myogenic DLK1 1 cells were identified during muscle regeneration in animal models in which the peak expression of Dlk1 mRNA and protein coincided with that of myoblast differentiation and fusion. In addition to perivascular DLK11 cells, interstitial DLK1 1 cells were numerous in regenerating muscle, and in agreement with colocalization studies of DLK1 and CD90/DDR2, qPCR of fluorescence-activated cell sorting DLK1 1 and DLK1 2 cells revealed that the majority of DLK11 cells isolated at day 7 of regeneration had a fibroblast-like phenotype. The existence of different DLK11 populations was confirmed in cultures of primary derived myogenic cells, in which large flat nonmyogenic DLK11 cells and small spindle-shaped cells coexpressing DLK1 and muscle-specific markers were observed. Myogenic differentiation was achieved when sorted DLK11 cells were cocultured together with primary myoblasts revealing a myogenic potential that was 10% of the DLK1 2 population. Transplantation of DLK1 1 cells into lacerated muscle did, however, not give rise to DLK1 1 cell-derived myofibers. We suggest that the DLK1 1 subpopulations identified herein each may contribute at different levels/time points to the processes involved in muscle development and remodeling. STEM CELLS 2009;27:898-908 Disclosure of potential conflicts of interest is found at the end of this article.

Scientifically, the pig is attractive because of a similar physiology to humans. The digestive, cardiovascular and urogenital system resemble the human systems, while the anatomy of the skin is very similar to the human skin. Also, metabolic activity and enzymatic processes have close parallels to the human situation (Kannosuke et al. 1986). As a result, the minipig is a preferred model in pharmacodynamic studies (Shimada et al. 1986), ADME studies (Ikeda & Sapienza 1995, Sapienza et al. 1986) acute and chronic systemic toxicology (Hyvonen et al. 1986, Klinghardt et al. 1981) and dermal toxicity studies (Hanhijarvi et al. 1985), but also in more specialized studies as fertility and teratological studies (Hayama & Kokue 1985, Jnrgensen 1994, Misawa et al. 1982) Economically, the minipig is attractive because of a low weight at birth, sexual maturity and adult age. Also, the enzymatic P-450 system reaches a mature level in the minipig at a small size, at an age of two months (Freudenthal et al. 1976). A small size is advantageous for both dosing size (often in small amounts synthesized test compound) and housing requirements. Also is it handle a small minipig than a large landrace pig.Ethically, the use of non-rodent species as primates and dogs in biomedical research is confronted with an increasing resistance from society. The pig is an advantageous alternutbe species, since it is accepted by society as a production animal and thus has a lower emotional merit.The Gottingen Minipig was developed in 1961-62 at the Institute of Animal Breeding and Genetics of the University of Gottingen (Germany), by crossing the Minnesota minipig with the Vietnamese potbelly swine and the German Landrace. This gave the Gottingen Minipig its present characteristics, being a small, white miniature pig with a good fertility and stable genetics. The Gottingen Minipig is an outbred animal, with less than 5% inbreeding (Glodek 1986).The Gottingen Minipig has a weight at birth of 350-450 g. Boars are sexually mature at an age of 3-4 months, weighing 6-8 kg, while sows are sexually mature at an age of 4-5 months, weighing 7-9 kg. The adult weight of the Gottingen Minipig, at an age of two years, is about 35-40 kg. Compared to other breeds of miniature swine, the Gottingen Minipig is among the smallest, with a weight less than the Yucatan Micropig (Meddahi 1994). Reside this, the Gottingen Minipig is advantageous because of a high producn'on standard at the full-barrier breeding centre near Dalmose (Denmark), resulting in a defined microbiology. 70-90 kg 40-45 kg 35-40 kgThe Gottingen Minipigs is successfully applied in dermal studies, oral studies and continuous infusion studies. Also in local toxicity studies, by intra-lipomatous injection, the Gottingen Minipig is a favourable model.Demuzl application allows testing for acute or chronic dermal irritation, dermal absorption and phototoxic effects. The Gottingen Minipig has a large, unpigmented skin surface, which makes it possible to use non-invasive techniques, such as reflectrome...

To detect early abnormalities in bone mineralization, the lumbar spine bone mineral density (BMD) of diabetic children with a diabetes onset of less than 5 years and treated with a similar insulin treatment scheme was measured at the level of the lumbar spine by dual-energy X-ray absorptiometry (DEXA), a most sensitive technique for detecting osteopenia in children. Fifteen male and 8 female children and adolescents (mean age ± SD: 12.5±3.7 years), 1–5 years after the clinical onset of their diabetes, were studied. Measurements of the lumbar spine (L₁–L₄) BMD, expressed in gHA/cm² and as a z-score for age, were performed with a commercial DEXA apparatus (Hologic QDR 1000 W, Hologic Inc., Waltham, USA). Calcium-phosphorus metabolism was studied by measuring the circulating levels of calcium, phosphorus, alkaline phosphatase, osteocalcin, 25-OH-vitamin D and parathyroid hormone and the urinary excretion of calcium and phosphorus. The mean BMD of the studied group was 0.75 (0.16) gHA/cm² giving a mean z-score of –0.31±0.95. Only 1 of the patients had a BMD lower than –2 SD. No sex difference in BMD z-score existed. BMD SD was positively correlated with height SD (R = 0.56, p < 0.005), but not with the age of the patients, the duration of the disease, the degree of metabolic control or the studied parameters of the calcium-phosphorus metabolism. In conclusion, diabetic children have a normal lumbar spine BMD during the first years of the disease, when a good metabolic control and no abnormalities in the calcium-phosphorus metabolism are present. As in normal children, areal BMD by DEXA is highly dependent on the body height, necessitating corrections if abnormalities in skeletal growth or pubertal development exist.

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The somatostatin receptor, which is overexpressed by many neuroendocrine tumors, is a well-known target for molecular imaging and peptide receptor radionuclide therapy. Recently, 57 Co-labeled DOTA-TOC, an octreotide analog, was shown to have the highest affinity yet found for somatostatin receptor subtype 2. The aim of this study was to evaluate the biologic effects of novel cobalt-labeled octreotide analogs targeting the somatostatin receptor to identify promising candidates for molecular imaging and Auger electron-based radionuclide therapy. Methods: Cobalt-labeled DOTATATE, DOTATOC, and DOTANOC were prepared with 57 Co or 58m Co for SPECT or Auger electron-based therapy, respectively. The cellular uptake and intracellular distribution of the radioligands were characterized with the pancreatic tumor cell line AR42J in vitro, including assessment of the therapeutic effects of 58m Co-DOTATATE via DNA double-strand break and proliferation assays. Comparisons with the therapeutic effects of 111 In-and 177 Lu-DOTATATE were also performed. Tumor uptake and normal tissue uptake were characterized in a subcutaneous pancreatic tumor mouse model. Results: All 3 cobalt-conjugated peptides resulted in time-dependent and receptor-specific uptake, with a high level (≥88%) of cellular internalization in vitro of the total cell-associated radioactivity. The DNA double-strand break yield showed a dose-dependent increase with activity, whereas cell survival showed a dose-dependent decrease. 58m Co-DOTATATE was significantly more efficient in cell killing per cumulated decay than 111 In-and 177 Lu-DOTATATE. The in vivo pharmacokinetic studies showed a high level of receptor-specific tumor uptake. Conclusion: All cobalt-labeled radioligands showed a high level of receptor-specific uptake both in vitro and in vivo in tumorbearing mice. Furthermore, 58m Co-DOTATATE showed considerable therapeutic effects in vitro and, thus, could be an effective agent for eradicating disseminated tumor cells and micrometastases. Thesomat ostatin receptor, which is overexpressed by many neuroendocrine tumors, is a well-known target for molecular imaging (i.e., PET and SPECT) and for peptide receptor radionuclide therapy (1,2). One of the most widely used radiopharmaceuticals for SPECT imaging of these tumors is 111 In-diethylenetriaminepentaacetic acid ( Recently, 57 Co-labeled DOTATOC was shown to have the highest affinity yet found for the somatostatin receptor subtype 2 (SSTR2) (6). Furthermore, the rate of internalization of this compound into the pancreatic tumor cell line AR42J was the highest found for any somatostatin-based radioligand. In a study by Uusijärvi et al. (7) of 59 therapeutic radionuclides (a, b, and Auger electron emitters), the Auger electron emitter 58m Co was the radionuclide that resulted in the second highest theoretic tumor-to-normal tissue dose rate ratio. Therefore, the therapeutic potency of the 58m Co radionuclide and the remarkable obtainable internalization rates and affinities for SSTR2-expressing tumor cells mak...