A 190 base pair, TGF-ß responsive tooth and fin enhancer is required for stickleback Bmp6 expression.

The ligands of the Bone Morphogenetic Protein (BMP) family of developmental signaling molecules are often under the control of complex cis-regulatory modules and play diverse roles in vertebrate development and evolution. Here, we investigated the cis-regulatory control of stickleback Bmp6. We identified a 190bp enhancer ~2.5 kilobases 5' of the Bmp6 gene that recapitulates expression in developing teeth and fins, with a core 72bp sequence that is sufficient for both domains. By testing orthologous enhancers with varying degrees of sequence conservation from outgroup teleosts in transgenic reporter gene assays in sticklebacks and zebrafish, we found that the function of this regulatory element appears to have been conserved for over 250 million years of teleost evolution. We show that a predicted binding site for the TGFß effector Smad3 in this enhancer is required for enhancer function and that pharmacological inhibition of TGFß signaling abolishes enhancer activity and severely reduces endogenous Bmp6 expression. Finally, we used TALENs to disrupt the enhancer in vivo and find that Bmp6 expression is dramatically reduced in teeth and fins, suggesting this enhancer is necessary for expression of the Bmp6 locus. This work identifies a relatively short regulatory sequence that is required for expression in multiple tissues and, combined with previous work, suggests that shared regulatory networks control limb and tooth development.

Impact of intraosseous versus intravenous resuscitation during in-hospital cardiac arrest: A retrospective study.

AIM: To compare outcomes between Intraosseous (IO) and peripheral intravenous (PIV) injection during in-hospital cardiac arrest (IHCA) and examine its utility in individuals with obesity. METHODS: We performed a retrospective cohort analysis of adult, atraumatic IHCA at a single tertiary care center. Subjects were classified as either IO or PIV resuscitation. The primary outcome of interest was survival to hospital discharge. The secondary outcomes of interest were survival with favourable neurologic status, rates-of-ROSC (ROR) and time-to-ROSC (TTR). Subgroup analysis among patients with BMI ≥ 30 kg/m2 was performed. RESULTS: Complete data were available for 1852 subjects, 1039 of whom met eligibility criteria. A total of 832 were resuscitated via PIV route and 207 via IO route. Use of IO compared to PIV was associated with lower overall survival to hospital discharge (20.8% vs 28.4% p = 0.03), lower rates of survival with favourable neurologic status (18.4% vs 25.2% p = 0.04), lower ROR (72.2% vs 80.7%) and longer TTR (12:38 min vs 9:01 min). After multivariate adjustment there was no significant differences between IO and PIV in rates of survival to discharge (OR 0.71, 95% CI 0.47-1.06, p = 0.09) or rates of survival with favourable neurologic status (OR 0.74, 95% CI 0.49-1.13, p = 0.16). The ROR and TTR remained significantly worse in the IO group. Subgroup analysis of patients with BMI ≥ 30 kg/m2 identified no benefit or harm with use of IO compared to PIV. CONCLUSION: Intraosseous medication delivery is associated with inferior rates-of-ROSC and longer times-to-ROSC compared to PIV, but no differences in overall survival to hospital discharge or survival with favourable neurologic status during IHCA.

Supportive care of right ventricular failure due to fat embolism syndrome.

Pulmonary fat embolism is a common phenomenon in cases of traumatic long bone fractures, with only a minority developing the more catastrophic Fat Embolism Syndrome (FES). Diagnosis is clinical and requires a high index of suspicion. Treatment remains under-investigated, with common interventions having low quality level-of-evidence and no mortality benefit. In severe cases, focus should be on supporting the failing right ventricle through use of inotropes, pulmonary vasodilators, and mechanical circulatory support. This requires a thorough understanding of the unique physiology through the pulmonary circulation.

Zebrafish models of skeletal dysplasia induced by cholesterol biosynthesis deficiency.

Human disorders of the post-squalene cholesterol biosynthesis pathway frequently result in skeletal abnormalities, yet our understanding of the mechanisms involved is limited. In a forward-genetic approach, we have found that a late-onset skeletal mutant, named kolibernu7 , is the result of a cis-acting regulatory mutation leading to loss of methylsterol monooxygenase 1 (msmo1) expression within pre-hypertrophic chondrocytes. Generated msmo1nu81 knockdown mutation resulted in lethality at larval stage. We demonstrated that this is a result of both cholesterol deprivation and sterol intermediate accumulation by creating a mutation eliminating activity of Lanosterol synthase (Lss). Our results indicate that double lssnu60;msmo1nu81 and single lssnu60 mutants survive significantly longer than msmo1nu81 homozygotes. Liver-specific restoration of either Msmo1 or Lss in corresponding mutant backgrounds suppresses larval lethality. Rescued mutants develop dramatic skeletal abnormalities, with a loss of Msmo1 activity resulting in a more-severe patterning defect of a near-complete loss of hypertrophic chondrocytes marked by col10a1a expression. Our analysis suggests that hypertrophic chondrocytes depend on endogenous cholesterol synthesis, and blocking C4 demethylation exacerbates the cholesterol deficiency phenotype. Our findings offer new insight into the genetic control of bone development and provide new zebrafish models for human disorders of the cholesterol biosynthesis pathway.