RNA Technology to Regenerate and Repair Alveolar Bone Defects

microRNA-200a (miR-200a) targets multiple signaling pathways that are involved in osteogenic differentiation and bone development. However, its therapeutic function in osteogenesis and bone regeneration remains unknown. In this study, we use in vitro and in vivo models to investigate the molecular function of miR-200a overexpression and miR-200a inhibition using a plasmid-based miR inhibitor system (PMIS) on osteogenic differentiation and bone regeneration. Inhibition of miR-200a using PMIS-miR-200a significantly increased osteogenic biomarkers of human embryonic palatal mesenchyme cells and promoted bone regeneration in rat tooth socket defects. In rat maxillary M1 molar extractions, the supporting tooth structures were removed with an implant drill to yield a 3-mm defect in the alveolar bone. A collagen sponge was inserted into the open alveolar defect and PMIS-miR-200a plasmid DNA was added to the sponge and the wound sutured to protect the sponge and close the defect. It was important to remove the existing tooth supporting structure, which can influence alveolar bone regeneration. The alveolar bone was regenerated in 4 wk. The collagen sponge acts to stabilize and deliver the PMIS-miR-200a DNA to cells entering the sponge in the bone defect. We show that mesenchymal stem cells expressing CD90 and Stro-1 enter the sponges, take up the DNA, and express PMIS-miR-200a. PMIS-miR-200a initiates a bone regeneration program in transformed cells in vivo. In vitro inhibition of miR-200a was found to upregulate Wnt and BMP signaling activity as well as Runx2, OCN, Lef-1, Msx2, and Dlx5 associated with osteogenesis. Liver and blood toxicity testing of PMIS-miR-200a-treated rats showed no increase in several biomarkers of liver disease. These results demonstrate the therapeutic function of PMIS-miR-200a for rapid bone regeneration. Furthermore, the studies were designed to demonstrate the ease of use of PMIS-miR-200a in solution and applied using a syringe in the clinic through a simple one-time application.

CACNA1S mutation-associated dental anomalies: A calcium channelopathy

OBJECTIVES

To identify the molecular etiology of distinct dental anomalies found in eight Thai patients and explore the mutational effects on cellular functions.

MATERIALS AND METHODS

Clinical and radiographic examinations were performed for eight patients. Whole exome sequencing, mutant protein modelling, qPCR, western blot analysis, scratch assays, immunofluorescence, confocal analysis, in situ hybridization, and scanning electron micrography of teeth were done.

RESULTS

All patients had molars with multiple supernumerary cusps, single-cusped premolars, and a reduction in root number. Mutation analysis highlighted a heterozygous c.865A>G; p.Ile289Val mutation in CACNA1S in the patients. CACNA1S is a component of the slowly inactivating L-type voltage-dependent calcium channel. Mutant protein modeling suggested that the mutation might allow leakage of Ca2+ or other cations, or a tightening, to restrict calcium flow. Immunohistochemistry analysis showed expression of Cacna1s in the developing murine tooth epithelium during stages of crown and root morphogenesis. In cell culture, the mutation resulted in abnormal cell migration of transfected CHO cells compared to wildtype CACNA1S, with changes to the cytoskeleton and markers of focal adhesion.

CONCLUSIONS

The malformations observed in our patients suggest a role for calcium signaling in organization of both cusps and roots, affecting cell dynamics within the dental epithelium.

Fatty liver biomarkers and insulin resistance indices in the prediction of non-alcoholic fatty liver disease in Ghanaian patients

BACKGROUND

Scant West African data on non-alcoholic fatty liver disease (NAFLD) means there is little representation of this population in the modelling used to derive biomarkers and predictive indices for risk stratification of patients for the presence of hepatic steatosis. This study evaluates the performance of the fatty liver index (FLI), hepatic steatosis index (HSI) and triglyceride-glucose (TyG) index and its derivatives in predicting ultrasound detected NAFLD in a locally resident population of Ghanaian participants.

METHODS AND FINDINGS

A post hoc analysis of data from a cross sectional assessment of NAFLD and cardiovascular risk was performed. Data from 210 participants without significant alcohol intake, or secondary causes of fatty liver and not on steatogenic drugs was evaluated. A structured questionnaire had been used to collect demographic data, medical and drug history. Anthropometry, blood sampling for liver chemistry and fasting lipids were performed. Hepatic steatosis was detected by ultrasonography. A retrospective analysis involving multivariate binary logistic regression assessed FLI, HIS, TyG (and its derivatives) as predictors of NAFLD with p < .05 considered statistically significant. Sensitivity, specificity, predictive values, likelihood ratios were calculated and accuracy of the proxies evaluated from area under the receiver operating characteristics curve (AUROC). All the biomarkers and indices were significantly associated with NAFLD (p ≤ .001). All the lipid and fatty liver indices assessed performed acceptably as predictors of NAFLD. FLI (AUC = 0.8, 95% CI [0.74-0.87]), TyG-WC (AUC = 0.81, 95% CI [0.75-0.88]) and TyG-WHtR (AUC = 0.81, 95% CI [0.74-0.88]) performed best at predicting NAFLD. Whilst in all cases the markers had good specificity (>90%) they lacked sufficient sensitivity with FLI having the highest sensitivity of 36.7%. Their overall accuracy was greater than 70% in each case.

CONCLUSION

The overall accuracy of HSI, FLI, TyG index and its derivatives (TyG WHtR, TyG BMI, TyG WC) was acceptable for predicting NAFLD in this population. Given their performance in this study and in light of their low cost, accessibility, easy interpretation and non-invasive nature; they are suitable tools for screening in the Ghanaian population.

Sox2 Controls Periderm and Rugae Development to Inhibit Oral Adhesions

In humans, ankyloglossia and cleft palate are common congenital craniofacial anomalies, and these are regulated by a complex gene regulatory network. Understanding the genetic underpinnings of ankyloglossia and cleft palate will be an important step toward rational treatment of these complex anomalies. We inactivated the Sry (sex-determining region Y)-box 2 (Sox2) gene in the developing oral epithelium, including the periderm, a transient structure that prevents abnormal oral adhesions during development. This resulted in ankyloglossia and cleft palate with 100% penetrance in embryos examined after embryonic day 14.5. In Sox2 conditional knockout embryos, the oral epithelium failed to differentiate, as demonstrated by the lack of keratin 6, a marker of the periderm. Further examination revealed that the adhesion of the tongue and mandible expressed the epithelial markers E-Cad and P63. The expanded epithelia are Sox9-, Pitx2-, and Tbx1-positive cells, which are markers of the dental epithelium; thus, the dental epithelium contributes to the development of oral adhesions. Furthermore, we found that Sox2 is required for palatal shelf extension, as well as for the formation of palatal rugae, which are signaling centers that regulate palatogenesis. In conclusion, the deletion of Sox2 in oral epithelium disrupts palatal shelf extension, palatal rugae formation, tooth development, and periderm formation. The periderm is required to inhibit oral adhesions and ankyloglossia, which is regulated by Sox2. In addition, oral adhesions occur through an expanded dental epithelial layer that inhibits epithelial invagination and incisor development. This process may contribute to dental anomalies due to ankyloglossia.

Migration intentions of Ghanaian medical students: the influence of existing funding mechanisms of medical education ("the fee factor")

BACKGROUND

To explore the effects of fee paying status on migration intentions of Ghanaian medical students.

DESIGN

Cross sectional questionnaire based survey.

SETTING

All established Ghanaian medical schools with students in their clinical years.

PARTICIPANTS

Fee-paying and non-fee-paying Ghanaian medical students in their clinical years.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Migration intentions of Ghanaian medical students after graduation, Allegiance to Government of Ghana.

RESULTS

Approximately half (49%) of the medical students surveyed had intentions of migrating after school. Over 48% of those with migration intentions plan on doing so immediately after completing their house job, while 44% plan to migrate at least one year after their house job. The most popular destination chosen by the potential migrant doctors was North America (38%). Fee-paying students were significantly more likely (OR=2.11, CI=1.32, 3.38) than non-fee-paying students to have intentions of migrating after their training. Secondly, fee-paying students were more likely (OR=9.66, CI=4.42, 21.12) than non-fee paying students to feel they owe no allegiance to the Government of Ghana because of their fee-paying status.

CONCLUSIONS

Medical Students' fee-paying status affects their intentions to migrate and their allegiance to the country after completion of their training.

Diabetic nephropathy with interstitial nephritis presenting with a false-positive anti-GBM antibody

A 56-year-old male with DM and HTN presented with flank pain and nausea. Review of systems was negative, physical examination was notable for mild hypovolemia and laboratory revealed BUN 51 mg/dl, creatinine (Cr) 5.1 mg/dl (baseline 1.5), Westergren ESR 122 mm/h, fractional excretion of sodium 0.2% and UA positive for blood and protein. Despite volume resuscitation the Cr continued to rise. Urine sediment analysis revealed granular casts, renal tubular epithelial cells and a negative Hansel's stain. Hemodialysis was initiated with Cr 13.7 mg/ dl for dyspnea and dysgeusia. Subsequent laboratory data revealed 2 separate positive anti-GBM antibody titers and prednisone therapy was initiated. Renal biopsy was performed for further diagnostic, therapeutic and prognostic information and demonstrated interstitial nephritis with linear IgG and albumin deposition consistent with diabetic nephropathy. Follow-up antibody titers were negative. prednisone was discontinued and Cr stabilized with conservative therapy. Anti-GBM antibody disease is characterized by circulating IgG antibodies directed against the glomerular basement membrane, specifically the alpha-3 (IV) collagen chain. Anti-GBM nephritis is a rapidly progressive, isolated glomerulonephritis in association with circulating anti-GBM antibodies. A positive immunofluorescence (IF) test is considered diagnostic in the appropriate clinical setting. Therapies include immunosuppressive agents to suppress new antibody production and plasmapheresis to eliminate circulating antibodies. Anti-GBM antibody is not rapidly cleared by steroid therapy and the recovery of renal function is rare if initiation Cr is greater than 7 mg/dl. This case demonstrates that the current ELISA for alpha-3 (IV) collagen is not pathognomonic for anti-GBM nephritis and that renal biopsy with IF for IgG and albumin may be indicated to prevent administration of potentially toxic treatment.

PRAM-1 is a novel adaptor protein regulated by retinoic acid (RA) and promyelocytic leukemia (PML)-RA receptor alpha in acute promyelocytic leukemia cells

The t(15;17) translocation, found in 95% of acute promyelocytic leukemia, encodes a promyelocytic leukemia (PML)-retinoic acid receptor alpha (RARalpha) fusion protein. Complete remission of acute promyelocytic leukemia can be obtained by treating patients with all-trans retinoic acid, and PML-RARalpha plays a major role in mediating retinoic acid effects in leukemia cells. A main model proposed for acute promyelocytic leukemia is that PML-RARalpha exerts its oncogenic effects by repressing the expression of retinoic acid-inducible genes critical to myeloid differentiation. By applying subtraction cloning to acute promyelocytic leukemia cells, we identified a retinoic acid-induced gene, PRAM-1 (PML-RARalpha target gene encoding an Adaptor Molecule-1), which encodes a novel adaptor protein sharing structural homologies with the SLAP-130/fyb adaptor. PRAM-1 is expressed and regulated during normal human myelopoiesis. In U937 myeloid precursor cells, PRAM-1 expression is inhibited by expression of PML-RARalpha in the absence of ligand and de novo superinduced by retinoic acid. PRAM-1 associates with other adaptors, SLP-76 and SKAP-55HOM, in myeloid cell lines and with protein tyrosine kinase lyn. By providing the first evidence that PML-RARalpha dysregulates expression of an adaptor protein, our data open new insights into signaling events that are disrupted during transformation by PML-RARalpha and induced by retinoic acid during de novo differentiation of acute promyelocytic leukemia cells.

Characterization of a novel model of pancreatic fibrosis and acinar atrophy

Significant fibrosis and acinar atrophy are characteristics of chronic pancreatitis; however, because of the lack of a reproducible model, early phases of these changes are poorly understood. We have developed a model of severe hyperstimulation and obstruction pancreatitis (SHOP) to better define the mechanisms of early pancreatic fibrogenesis. Sprague-Dawley rats were used and SHOP was induced by complete pancreatic duct obstruction and daily cerulein hyperstimulation (50 microg/kg intraperitoneally). Animals were killed at 24, 48, 72, and 96 hours. Control animals underwent sham operation and received no cerulein. Pancreata were prepared for hematoxylin and eosin and sirius red (collagen-specific) staining and for hydroxyproline assay (measure of total collagen content). We found moderate amounts of edema and inflammation but minimal parenchymal necrosis. Significant loss of acinar cell mass was noted by 48 hours, and normal acinar cells were essentially absent by 96 hours. Tissue collagen content increased with time and large amounts of interstitial collagen were detected by 72 hours. In conclusion, SHOP is a novel model of early pancreatic fibrosis associated with minimal necrosis and a significant decrease in acinar cell mass, making it an ideal model to study the early cellular mechanisms of pancreatic fibrogenesis.