Effect of Pitching Restrictions and Mound Distance on Youth Baseball Pitch Counts.

Background: Studies have shown that higher pitch counts are directly related to a greater incidence of elbow and shoulder pain among youth baseball pitchers. Purpose/Hypothesis: The purpose of this study was to examine the effect of different pitching restriction rules on the number of pitches thrown in youth baseball leagues. We hypothesized that more pitches would be thrown in leagues with inning restrictions versus leagues with pitch count restrictions as well as in leagues with a longer mound distance (from pitching mound to home plate). Study Design: Cohort study; Level of evidence, 2. Methods: Pitch count data were collected for 2 consecutive years over a 10-week season from 3 different leagues of 9- to 12-year-old baseball players in a single city. The Eastern league had a pitch count restriction and 46-ft (14.02-m) mound distance. The Southeastern and South leagues' pitching restrictions were based on innings per week. The Southeastern league had a 50-ft (15.24-m) mound distance, while the South league had a 46-ft mound distance. Comparisons of total seasonal pitches thrown were made of the 3 highest-volume pitchers on each team. League averages for each value were then compared utilizing analysis of variance with Bonferroni post hoc analysis. The number of pitchers in each league who threw >600 pitches per season was compared using the chi-square test. Results: No significant difference in seasonal pitch counts or innings pitched was noted between the Eastern and South leagues, which differed only in their pitching restrictions. The Southeastern league, with a longer mound distance, was found to have higher seasonal pitch counts per thrower (598 ± 195 pitches) than the South league (463 ± 198 pitches) for the 3 highest-volume throwers for each team (P = .004). The Southeastern league also had a significantly larger number of pitchers who threw >600 pitches per season (33 vs 20 for Eastern and 13 for South; P = .009). Conclusion: There was no significant difference in seasonal pitch counts when the leagues in this study differed based on pitching restrictions. However, the league with a greater mound distance (Southeastern) had higher seasonal pitch counts for the highest-volume throwers. Pitching restrictions based on pitch counts, as opposed to innings, may be advisable.

Biomechanical Properties of Small-Size Hamstring Autografts.

Purpose To evaluate small-size hamstring (HS) autografts for biomechanical properties and determine a threshold diameter necessary for appropriate reconstruction. Methods In a controlled laboratory setting, biomechanical testing was performed upon 15 hamstring autografts. The grafts were divided into three groups by diameter, with five grafts each at diameter sizes of 6, 7, and 8 mm. Testing of the specimens was performed using an MTS 858 (Materials Testing System, Eden Prairie, MN). We determined load to failure by looking at the maximum load as well as the stiffness of the graft. Statistical analysis was performed via analysis of variance (ANOVA) testing with Tukey's post-hoc test and P-values set at 0.05. Results There was a significant difference in ultimate tensile strength for the different size grafts: 1990 +/- 302.42 N for 6 mm grafts (n=5), 2179 +/- 685.36 N for the 7 mm grafts (n=5), and 3074 +/- 781 N for 8 mm grafts (n=5). This was statistically significant for the group overall (p=0.039), as well as between the 6 mm and 8 mm grafts (p=0.044). Graft stiffness for the 6 mm grafts was 317 +/- 85 N (n=5), 288.6 +/- 66 for 7 mm grafts (n=5), and 428.053 +/- 83 for 8 mm grafts (n=5). This achieved statistical significance for the group overall (p =0.037) as well as between the 8 mm and 7 mm grafts. Conclusions The biomechanical data presented here demonstrate that graft diameter is highly correlated with ultimate tensile strength and stiffness. Clinical relevance When viewing this biomechanical data in conjunction with prior clinical data, consideration should be given for the supplementation of an HS autograft as the size decreases below 8 mm.

Minimally invasive versus conventional joint arthroplasty.

With an aging population, as well as a heightened interest in physical activity, the demand for surgical treatment of osteoarthritis of the knee, hip, and shoulder has continued to expand. This demand traditionally has been met with total joint replacements as the definitive treatment. However, with the development of newer, minimally invasive techniques, patients are being offered a greater variety of options for pain relief and improvement in function. These surgical options, varying widely from arthroscopic treatment to partial joint replacements, have been met with mixed results as they have been applied to the treatment of osteoarthritis. Although they are limited in their application and target population, minimally invasive procedures may greatly enhance the outcome of the patient, as well as prevent or delay the need for future total joint arthroplasty. The purpose of this article is to review minimally invasive surgical options for the treatment of osteoarthritis of the hip, knee, and shoulder. We also examine their appropriate application, limitations, clinical outcomes, and associated complications. A brief review of total joint arthroplasty for the aforementioned joints has been included to provide a comparison of the associated clinical outcomes and surgical complications.

A compendium of the mouse mammary tumor biologist: from the initial observations in the house mouse to the development of genetically engineered mice.

For over a century, mouse mammary tumor biology and the associated mouse mammary tumor virus (MMTV) have served as the foundation for experimental cancer research, in general, and, in particular, experimental breast cancer research. Spontaneous mouse mammary tumors were the basis for studies of the natural history of neoplasia, oncogenic viruses, host responses, endocrinology and neoplastic progression. However, lacking formal proof of a human mammary tumor virus, the preeminence of the mouse model faded in the 1980s. Since the late 1980s, genetically engineered mice (GEM) have proven extremely useful for studying breast cancer and have become the animal model for human breast cancer. Hundreds of mouse models of human breast cancer have been developed since the first demonstration in 1984. The GEM have attracted a new generation of molecular and cellular biologists eager to apply their skill sets to these surrogates of the human disease. Newcomers often enter the field without an appreciation of the origins of mouse mammary tumor biology and the basis for many of the prevailing concepts. Our purpose in writing this compendium is to extend an "olive branch" while simultaneously deepen the knowledge of the novice mouse mammary tumor biologist as they journey into a field rich in pathology and genetics spanning several centuries.

Global expression profiling reveals regulation of CTGF/CCN2 during lactogenic differentiation.

Mammary epithelial cells go through a series of developmental changes during pregnancy and lactation including proliferation, differentiation, secretion and apoptosis. HC11 mouse mammary epithelial cells, which undergo lactogen-induced differentiation in cell culture, were used to follow the changes in gene expression during this process. The expression profiles of over 20,000 genes were compared in HC11 cells undergoing lactogenic differentiation to non-differentiated cells using DNA microarray analysis. Greater than two fold changes were detected in 998 genes in the differentiated cells versus growth controls. Several genes including CTGF/CCN2 exhibited greater than five-fold increase. Validation of the gene expression pattern for more than twenty genes was performed. The results indicate the involvement of numerous genes and pathways in the differentiation of mouse mammary epithelial cells in culture and they identify genetic pathways associated with specific transcriptional regulation. In addition, the expression of a subset of genes regulated by lactogenic differentiation in HC11 cells, including CTGF/CCN2 and osteopontin, was examined in mouse mammary glands revealing expression during pregnancy and lactation that declined during involution of the glands. To probe the mechanism by which epidermal growth factor (EGF), a known inhibitor of lactogenic differentiation in HC11 cells, blocks lactogenesis, the HC11 cells stimulated with lactogenic hormone in the presence of EGF were profiled. This data revealed EGF regulation of a specific subset of genes including important cell cycle regulators. The studies confirm the value of expression profiling in defining gene transcription associated with differentiation of mammary epithelial cells.

Glucocorticoid induced expression of connective tissue growth factor contributes to lactogenic differentiation of mouse mammary epithelial cells.

The response of mammary epithelial cells to basement membrane and stroma induced signals contributes to the degree of differentiation in this tissue. The studies reported here indicate that connective tissue growth factor (CTGF) is highly elevated during lactogenic differentiation of the HC11 mouse mammary epithelial cell line. In addition, CTGF is expressed in the mouse mammary gland during pregnancy and lactation and it is expressed in primary mammary epithelial cell cultures established from pregnant mice. In HC11 cells CTGF is transcriptionally regulated by dexamethasone, but not by estrogen or progesterone, and CTGF expression is not dependent on TGFbeta. CTGF contributes to and is required for lactogenic differentiation of HC11 cells, as demonstrated by increased differentiation following expression of plasmid-encoded CTGF and decreased differentiation following depletion of endogenous CTGF with siRNA. Moreover, HC11 mouse mammary epithelial cells infected with an adenoviral vector encoding CTGF exhibit increased lactogenic differentiation. Plasmid vector-induced elevation of CTGF levels also increased the level of beta1 integrin in HC11 cells. Because the production of stromal factors is an important component of differentiation in mammary epithelial cells, the regulation of CTGF by glucocorticoids may play a critical role in this aspect of the control of differentiation. The studies reported here provide important information on the role of CTGF in mammary epithelial cell differentiation.

Mouse mammary tumor biology: a short history.

For over a century, mouse mammary tumor biology and the associated Mouse mammary tumor virus (MMTV) have served as the foundation for experimental cancer research, in general, and, in particular, experimental breast cancer research. Spontaneous mouse mammary tumors were the basis for studies of the natural history of neoplasia, oncogenic viruses, host responses, endocrinology, and neoplastic progression. However, lacking formal proof of a human mammary tumor virus, the preeminence of the mouse model faded in the 1980s. Since the late 1980s, genetically engineered mice (GEM) have proven extremely useful for studying breast cancer and have become the animal model for human breast cancer. Hundreds of mouse models of human breast cancer have been developed since the first demonstration, in 1984, that the mouse mammary gland could be molecularly targeted and used to test the oncogenicity of candidate human genes. Now, very few scientists can avoid using a mouse model to test the biology of their favorite gene. The GEM have attracted a new generation of molecular and cellular biologists eager to apply their skills to these surrogates of the human disease. Newcomers often enter the field without an appreciation of the origins of mouse mammary tumor biology and the basis for many of the prevailing concepts. Our purpose in writing this short history of mouse mammary tumor biology is to provide a historical perspective for the benefit of the newcomers. If Einstein was correct in that "we stand on the shoulders of giants," the neophytes should meet their giants.

Evaluation of cruciate and slot auxiliary screw head design modifications for extracting stripped screw heads.

Slotted and cruciate auxiliary screw head design modifications for "salvaging" a stripped hexagonal head screw were studied. Thirty screws were divided into 3 groups: Group 1 = control without modification, Group 2 = auxiliary cruciate design modification and Group 3 = auxiliary slot design modification. Screws were inserted into adhesive filled high-density synthetic bone tunnels using a hexagonal driver. Group 1 screws were removed using a hexagonal driver. Group 2 and group 3 screws were removed using drivers that matched their respective auxiliary design modifications. All group 1 and group 3 screws (100%) were effectively extracted. Three of 10 (30%) group 2 screws could not be effectively extracted. Group 2 screws displayed greater stripping and deformation than the other groups. The auxiliary slot design modification withstood comparable extraction torques as control screws without significant deformation. Screws with a cruciate design modification displayed more frequent failure, greater stripping and deformation.

Modulation of TGF-beta signaling by EGF-CFC proteins.

Members of the transforming growth factor-beta (TGF-beta) family of ligands exhibit potent growth-suppressive and/or apoptosis-inducing effects on different types of cells. They perform essential roles in the elimination of damaged or abnormal cells from healthy tissues. On the other hand, TGF-betas have also been shown to act as tumor-promoting cytokines in a number of malignancies that are capable of stimulating extracellular matrix production, cell migration, invasion, angiogenesis, and immune suppression. Dissecting the complex, multifaceted roles of different TGF-beta-related peptides especially during the development of pathological conditions and in carcinogenesis is an area of continuous research and development. The characterization of EGF-CFC proteins as essential co-receptors that contribute to the modulation of the physiological activities of some of the TGF-beta ligands will be beneficial for future medical research and the adaptation and possible readjustment of currently applied therapeutic regimes.

Notch4 intracellular domain binding to Smad3 and inhibition of the TGF-beta signaling.

We present evidence that Notch4ICD attenuates TGF-beta signaling. Cells expressing the activated form of the Notch4 receptor (ICD4) were resistant to the growth-inhibitory effects of TGF-beta. Notch4ICD was found to bind to Smad2, Smad3 and Smad4 but with higher affinity to Smad3. Deletion analysis showed that binding of Smad3 to ICD4 was mediated by its MH2 domain and was not dependent on the presence of the RAM23 region in ICD4. Using two TGF-beta/Activin reporter luciferase assays, RT-PCR and Western blot analysis, we demonstrate that ICD4 and ICD4 deltaRAM23 inhibit Smad-binding element and 3TP luciferase reporter activity and PAI-1 gene expression. MCF-7 human breast cancer cells express Notch4ICD (ICD4) and are resistant to the growth-inhibitory effects of TGF-beta. Blockage of Notch4 processing to ICD4 by gamma-secretase inhibitor renders MCF-7 cells sensitive to growth inhibition by TGF-beta. The interplay between these two signaling pathways may be a significant determinant during mammary tumorigenesis.

Overexpression of human Cripto-1 in transgenic mice delays mammary gland development and differentiation and induces mammary tumorigenesis.

Overexpression of Cripto-1 has been reported in several types of human cancers including breast cancer. To investigate the role of human Cripto-1 (CR-1) in mammary gland development and tumorigenesis, we developed transgenic mice that express the human CR-1 transgene under the regulation of the whey acidic protein (WAP) promoter in the FVB/N mouse background. The CR-1 transgene was detected in the mammary gland of 15-week-old virgin WAP-CR-1 female mice that eventually developed hyperplastic lesions. From mid-pregnancy to early lactation, mammary lobulo-alveolar structures in WAP-CR-1 mice were less differentiated and delayed in their development due to decreased cell proliferation as compared to FVB/N mice. Early involution, due to increased apoptosis, was observed in the mammary glands of WAP-CR-1 mice. Higher levels of phosphorylated AKT and MAPK were detected in mammary glands of multiparous WAP-CR-1 mice as compared to multiparous FVB/N mice suggesting increased cell proliferation and survival of the transgenic mammary gland. In addition, more than half (15 of 29) of the WAP-CR-1 multiparous female mice developed multifocal mammary tumors of mixed histological subtypes. These results demonstrate that overexpression of CR-1 during pregnancy and lactation can lead to alterations in mammary gland development and to production of mammary tumors in multiparous mice.

Human Cripto-1 overexpression in the mouse mammary gland results in the development of hyperplasia and adenocarcinoma.

Human Cripto-1 (CR-1) is overexpressed in approximately 80% of human breast, colon and lung carcinomas. Mouse Cr-1 upregulation is also observed in a number of transgenic (Tg) mouse mammary tumors. To determine whether CR-1 can alter mammary gland development and/or may contribute to tumorigenesis in vivo, we have generated Tg mouse lines that express human CR-1 under the transcriptional control of the mouse mammary tumor virus (MMTV). Stable Tg MMTV/CR-1 FVB/N lines expressing different levels of CR-1 were analysed. Virgin female MMTV/CR-1 Tg mice exhibited enhanced ductal branching, dilated ducts, intraductal hyperplasia, hyperplastic alveolar nodules and condensation of the mammary stroma. Virgin aged MMTV/CR-1 Tg mice also possessed persistent end buds. In aged multiparous MMTV/CR-1 mice, the hyperplastic phenotype was most pronounced with multifocal hyperplasias. In the highest CR-1-expressing subline, G4, 38% (12/31) of the multiparous animals aged 12-20 months developed hyperplasias and approximately 33% (11/31) developed papillary adenocarcinomas. The long latency period suggests that additional genetic alterations are required to facilitate mammary tumor formation in conjunction with CR-1. This is the first in vivo study that shows hyperplasia and tumor growth in CR-1-overexpressing animals.

Nodal and Cripto-1: embryonic pattern formation genes involved in mammary gland development and tumorigenesis.

Members of the TGFbeta superfamily and EGF-CFC family, such as Nodal and Cripto, are important mediators of anterior-posterior and left-right axis specification during embryogenesis. In this paper, we review the role of Nodal and Cripto as critical morphogen-like molecules, with an emphasis on Nodal and EGF-CFC signaling during embryonic pattern formation. New evidence from gene expression and transgenic mouse studies have shown that both Nodal and Cripto-1 are expressed within the mammary duct and that modulation of these genes can disrupt normal branching morphogenesis resulting in epithelial disorganization and defective ductal architecture. We describe these new findings and propose that Cripto and Nodal are candidate mammary morphogens. Finally, the data linking overexpression of Cripto and perturbations of Cripto signaling to cell transformation and tumor formation are discussed. The fact that Cripto can modulate multiple pathways suggests it may act to deregulate growth inhibitors/homeostasis factors early in the cell transformation process and then activate prosurvival pathways dependent on MAPK and PI3K/Akt later in fully transformed phenotypes.

Cadmium mimics the in vivo effects of estrogen in the uterus and mammary gland.

It has been suggested that environmental contaminants that mimic the effects of estrogen contribute to disruption of the reproductive systems of animals in the wild, and to the high incidence of hormone-related cancers and diseases in Western populations. Previous studies have shown that functionally, cadmium acts like steroidal estrogens in breast cancer cells as a result of its ability to form a high-affinity complex with the hormone binding domain of the estrogen receptor. The results of the present study show that cadmium also has potent estrogen-like activity in vivo. Exposure to cadmium increased uterine wet weight, promoted growth and development of the mammary glands and induced hormone-regulated genes in ovariectomized animals. In the uterus, the increase in wet weight was accompanied by proliferation of the endometrium and induction of progesterone receptor (PgR) and complement component C3. In the mammary gland, cadmium promoted an increase in the formation of side branches and alveolar buds and the induction of casein, whey acidic protein, PgR and C3. In utero exposure to the metal also mimicked the effects of estrogens. Female offspring experienced an earlier onset of puberty and an increase in the epithelial area and the number of terminal end buds in the mammary gland.

Effect of exogenous epidermal-like growth factors on mammary gland development and differentiation in the estrogen receptor-alpha knockout (ERKO) mouse.

The development of the mouse mammary gland requires the interaction between several different ovarian and pituitary hormones such as estrogen, progesterone and prolactin as well as several locally-derived growth factors in the mammary gland such as epidermal growth factor (EGF), transforming growth factor alpha (TGFalpha), amphiregulin (AR) and heregulin (HRG). The focus of this study was to investigate the degree of mammary growth and differentiation in the adult, virgin mammary gland of wild type (wt) and estrogen receptor knockout (ERKO) females that lack estrogen receptor alpha (ERalpha) after reciprocal transplantation into the cleared mammary fat pad of virgin wt or ERKO mice. In addition, we assessed the local response of ERKO mammary tissue to TGFalpha or HRGbeta1 delivered from slow release-Elvax pellets. Our initial results indicated that when we transplanted virgin wt mammary tissue into ERKO mammary fat pads, mammary morphogenesis failed to occur. However, when transplanted virgin ERKO mammary tissue was transplanted into fat pads of virgin or pregnant wt mice, the development and differentiation of lobuloalveoli was readily observed. In addition, treatment of the virgin ERKO mammary gland with TGFalpha or HRGbeta1 stimulated ducts to undergo localized branching and growth and both growth factors induced secretory differentiation as evidenced by the production of milk proteins, caseins and/or whey acidic protein (WAP). The results from this study imply that in ERKO mammary tissue. ERKO ductal epithelium has the capacity to proliferate and differentiate in response to non-estrogenic, morphogenic stimuli.

Cripto-1 activates nodal- and ALK4-dependent and -independent signaling pathways in mammary epithelial Cells.

Cripto-1 (CR-1), an epidermal growth factor-CFC (EGF-CFC) family member, has a demonstrated role in embryogenesis and mammary gland development and is overexpressed in several human tumors. Recently, EGF-CFC proteins were implicated as essential signaling cofactors for Nodal, a transforming growth factor beta family member whose expression has previously been defined as embryo specific. To identify a receptor for CR-1, a human brain cDNA phage display library was screened using CR-1 protein as bait. Phage inserts with identity to ALK4, a type I serine/threonine kinase receptor for Activin, were identified. CR-1 binds to cell surface ALK4 expressed on mammalian epithelial cells in fluorescence-activated cell sorter analysis, as well as by coimmunoprecipitation. Nodal is coexpressed with mouse Cr-1 in the mammary gland, and CR-1 can phosphorylate the transcription factor Smad-2 in EpH-4 mammary epithelial cells only in the presence of Nodal and ALK4. In contrast, CR-1 stimulation of mitogen-activated protein kinase and AKT in these cells is independent of Nodal and ALK4, suggesting that CR-1 may modulate different signaling pathways to mediate its different functional roles.

Suppression of Neu-induced mammary tumor growth in cyclin D1 deficient mice is compensated for by cyclin E.

Amplification and/or overexpression of the receptor tyrosine kinase HER2/Neu and the cell cycle regulatory gene cyclin D1 are frequently associated with human breast cancer. We studied the functional significance of cyclin D1 in Neu-induced mammary oncogenesis by developing mice overexpressing either wild-type or mutant Neu in a cyclin D1 deficient background. The absence of cyclin D1 suppresses mammary tumor formation induced by the wild-type or activated mutant form of Neu, which promote multi- and single-step progression of tumorigenesis, respectively. These data indicate that cyclin D1 is preferentially required for Neu-mediated signal transduction pathways in mammary oncogenesis. Significantly, 35% of mutant Neu/cyclin D1(-/-) mice regained mammary tumor potential due to compensation by cyclin E. Thus, shared targets of cyclins D1 and E are important in modulating Neu function in mammary tumorigenesis. Our results imply that the combinatorial inhibition of cyclins D1 and E might be useful in the treatment of malignancies induced by Neu.

Identification of Stem Cell Units in the Terminal End Bud and Duct of the Mouse Mammary Gland.

The mouse mammary gland may undergo cycles of proliferation, terminal differentiation, tissue remodeling, and more importantly malignant transformation.Mammary epithelial stem cells and their progeny participate in these processes.Mammary epithelial stem cells are multipotent, exhibit properties of self renewal (up to 7 divisions)and may exist either as long-lived nondividing cells or as proliferating-differentiating cells. The focus of this study was to locate stem cells by identifying them as long-lived, label-retaining mammary epithelial cells (LRCs)in growth active (developing)or growth static (aged)mammary ducts. Initially, primary epithelial cells were pulse labeled with either fluorescent tracker dye and/or BrdU. Cells were then transplanted into cleared juvenile syngeneic mammary fat pads and held for 5 weeks or 8 weeks. In this study, we demonstrate that LRCs are stem cells and their progeny (transitional cells)are arranged as transitional units (TUs). Additionally, TUs are located every 250 +/- 75 &mgr;m in ducts or in the terminal end bud 200-600 &mgr;m in diameter. Molecules expressed in TUs were Zonula Occludens-1 and alpha-catenin proteins which were significantly detected in 75%-91% (P <0.001)of the LRCs cells that make up the TU. These data suggest that transitional units may be a group of label-retaining stem cells and maybe involved in the developmental or cancer process.