Thyroid Progenitors Are Robustly Derived from Embryonic Stem Cells through Transient, Developmental Stage-Specific Overexpression of Nkx2-1

The clinical importance of anterior foregut endoderm (AFE) derivatives, such as thyrocytes, has led to intense research efforts for their derivation through directed differentiation of pluripotent stem cells (PSCs). Here, we identify transient overexpression of the transcription factor (TF) NKX2-1 as a powerful inductive signal for the robust derivation of thyrocyte-like cells from mouse PSC-derived AFE. This effect is highly developmental stage specific and dependent on FOXA2 expression levels and precise modulation of BMP and FGF signaling. The majority of the resulting cells express thyroid TFs (Nkx2-1, Pax8, Foxe1, Hhex) and thyroid hormone synthesis-related genes (Tg, Tpo, Nis, Iyd) at levels similar to adult mouse thyroid and give rise to functional follicle-like epithelial structures in Matrigel culture. Our findings demonstrate that NKX2-1 overexpression converts AFE to thyroid epithelium in a developmental time-sensitive manner and suggest a general methodology for manipulation of cell-fate decisions of developmental intermediates.

Labeling of Breast Cancer Patient-derived Xenografts with Traceable Reporters for Tumor Growth and Metastasis Studies

The use of preclinical models to study tumor biology and response to treatment is central to cancer research. Long-established human cell lines, and many transgenic mouse models, often fail to recapitulate the key aspects of human malignancies. Thus, alternative models that better represent the heterogeneity of patients' tumors and their metastases are being developed. Patient-derived xenograft (PDX) models in which surgically resected tumor samples are engrafted into immunocompromised mice have become an attractive alternative as they can be transplanted through multiple generations,and more efficiently reflect tumor heterogeneity than xenografts derived from human cancer cell lines. A limitation to the use of PDXs is that they are difficult to transfect or transduce to introduce traceable reporters or to manipulate gene expression. The current protocol describes methods to transduce dissociated tumor cells from PDXs with high transduction efficiency, and the use of labeled PDXs for experimental models of breast cancer metastases. The protocol also demonstrates the use of labeled PDXs in experimental metastasis models to study the organ-colonization process of the metastatic cascade. Metastases to different organs can be easily visualized and quantified using bioluminescent imaging in live animals, or GFP expression during dissection and in excised organs. These methods provide a powerful tool to extend the use of multiple types of PDXs to metastasis research.

Reduction of Lactobacillus in the milks of cows with subclinical mastitis

Clinical and subclinical bovine mastitis are the most frequent diseases encountered on dairy farms worldwide, which cause significant economic loss and veterinary cost. The mastitic disease status is associated with increases in both milk bacterial pathogens and somatic cell count (SCC). Although it is well established that the mastitic pathogens generally correlate with the milk SCC, to our knowledge, the correlation between the probiotic genus, Lactobacillus, and the mastitic causative bacteria and SCC have not been determined previously. Thus, in this study, milk samples from 12 mild and 28 severe subclinical mastitic dairy cows were collected from the same farm. The overall milk bacterial load was quantified with the total plate count method. The Lactobacillus genus and 4 common clinical and subclinical mastitic pathogens (Escherichia coli, Staphylococcus aureus, Streptococcus agalactiae, and Trueperella pyogenes) in the sampled milk were enumerated by quantitative PCR. Mild and severe subclinical mastitic samples were distinctly separated on the principal component analysis score plot generated based on the quantities of these 5 target bacteria, suggesting that clear differences existed in the microbiological composition between the two sample groups. Based on comparison with the pairwise Mann-Whitney test, the mild subclinical mastitic dairy cows had a significantly higher amounts of lactobacilli (P=0.0175), but lower E. coli (P=0.0002), S. aureus (P<0.0001), S. agalactiae (P=0.0001) and T. pyogenes (P=0.0044) quantities, while an opposite trend occurred in the severe subclinical mastitic group. The negative correlation between Lactobacillus and the pathogenic bacteria, as well as the SCC, was confirmed with Spearman correlation analysis. Data generated from the current study may hint to a close relationship between Lactobacillus and the health of bovine udder.

The diversity of intestinal microbiota of Mongolians living in Inner Mongolia, China

The Mongolian nationality has developed their unique lifestyle and dietary habit for thousands of years. However, by now, little research has been focused on Mongolian gut microbiota and how it is related to different dietary habits. In this study, denaturing gradient gel electrophoresis (DGGE) and quantitative polymerase chain reaction (qPCR) methods were applied to reveal the diversity of predominant gut bacteria of 48 healthy Mongolians recruited from Hohhot city and the Xilin Gol pasturing area in Inner Mongolia. Compared to similar studies of other nationalities, results from the present study have confirmed that the composition of Mongolian gut microbiota is highly similar at the phylum level (Firmicutes, Bacteroidetes, Proteobacteria and Actinobacteria) but variable at the genus level. Especially, the numbers of Phascolarctobacterium, Lactobacillus and Bifidobacterium are rather high. DGGE profiles of Lactobacillus and Bifidobacterium revealed that Lactobacillus casei, Bifidobacterium longum and Bifidobacterium animalis subsp. lactis were predominant in the gut of the Mongolian subjects studied. On the contrary, Lactobacillus helveticus was detected in every pasturing area Mongolian, but not in any of the Hohhot city Mongolians. qPCR results revealed that the numbers of Lactobacillus and Bifidobacterium of Xilin Gol Mongolians were significantly higher (P<0.05) than that of Hohhot Mongolians, whereas the numbers of Enterobacterium were significantly lower (P<0.05). In addition, by partial least squares discriminate analysis and cluster analysis of data generated from DGGE and qPCR experiments, a striking difference in the composition of intestinal microbiota of Mongolians living in Hohhot city and the Xilin Gol pasturing area has been found. This study clearly shows that diet affects the microbiota composition of Mongolians living in different circumstances, i.e. urban versus rural.

miR-129 regulates cell proliferation by downregulating Cdk6 expression

Reduced expression of miR-129 has been reported in multiple tumor cell lines and in primary tumors including medulloblastoma, undifferentiated gastric cancers, lung adenocarcinoma, endometrial cancer and colorectal carcinoma. There is also recent evidence of an anti-proliferative activity of miR-129 in tumor cell lines. Still, little is known about how miR-129 regulates cell proliferation. Here we found that lentiviral-mediated overexpression of miR-129 in mouse lung epithelial cells (E10 cells) results in significant G(1) phase arrest that eventually leads to cell death. miR-129 induce G(1) phase arrest in multiple human lung adenocarcinoma cell lines, suggesting miR-129 targeting of G(1)/S phase-specific regulators. Interestingly, we show that Cdk6, a kinase involved in G(1)-S transition, is a direct target of miR-129. We also found the downregulation of three other cell cycle-related novel targets of miR-129, including Erk1, Erk2 and protein kinase C epsilon (Prkce). We further show that among these targets, only Cdk6 is functionally relevant. Restoring expression of Cdk6, but not Prkce partially rescues the cell growth arrest and cell death phenotype that results from miR-129 overexpression. Together, our data indicate that miR-129 plays an important role in regulating cell proliferation by downregulation of Cdk6.

Spontaneous vaginal delivery: a risk factor for Erb's palsy?

OBJECTIVE

Our purpose was to determine whether Erb's palsies occurring in the absence of shoulder dystocia differ from those occurring after shoulder dystocia.

STUDY DESIGN

We compared the time course of resolution and incidence of persistent injury at 1 year of age in 17 cases of Erb's palsy without shoulder dystocia and 23 cases associated with shoulder dystocia.

RESULTS

The rate of persistence at 1 year was significantly higher in those Erb's cases without identified shoulder dystocia, 7 of 17 (41.2%) versus 2 of 23 (8.7%), p = 0.04. These cases of Erb's palsies also took longer to resolve (6.4 +/- 0.9 vs 2.6 +/- 0.7 months, p = 0.002), had a higher rate of associated clavicular fracture (12 of 17 vs 5 of 23, p = 0.006), and were more likely to occur in the posterior arm (10 of 15 vs 4 of 21, p = 0.009).

CONCLUSIONS

Erb's palsy occurring without shoulder dystocia may be a qualitatively different injury than that occurring with shoulder dystocia.