Germline sex determination regulates sex-specific signaling between germline stem cells and their niche.

Establishing germ cell sexual identity is critical for development of male and female germline stem cells (GSCs) and production of sperm or eggs. Germ cells depend on signals from the somatic gonad to determine sex, but in organisms such as flies, mice, and humans, the sex chromosome genotype of the germ cells is also important for germline sexual development. How somatic signals and germ-cell-intrinsic cues combine to regulate germline sex determination is thus a key question. We find that JAK/STAT signaling in the GSC niche promotes male identity in germ cells, in part by activating the chromatin reader Phf7. Further, we find that JAK/STAT signaling is blocked in XX (female) germ cells through the action of the sex determination gene Sex lethal to preserve female identity. Thus, an important function of germline sexual identity is to control how GSCs respond to signals in their niche environment.

Point-of-care ultrasound to confirm endotracheal tube cuff position in relationship to the cricoid in the pediatric population.

BACKGROUND: Anatomically, the subglottic area and the cricoid ring are the narrowest portions of the larynx. To limit the potential for damage related to mucosal pressure injuries from the presence of an endotracheal tube, the cuff should be placed below the cricoid in children. Previously, no clinical or imaging method has been used in real time to determine the exact location of the endotracheal tube cuff after endotracheal intubation. Point-of-care ultrasound may provide an option as a safe and rapid means of visualizing the endotracheal tube cuff and its relationship to the cricoid ring thereby achieving ideal endotracheal tube cuff positioning-below the cricoid. METHODS: In this prospective, nonrandomized trial, point-of-care ultrasound was used following endotracheal intubation in children to evaluate the position of the endotracheal tube cuff in relationship to the cricoid and tracheal rings. After anesthesia was induced and the trachea was intubated, the endotracheal tube cuff and its position in relation to the cricoid and tracheal rings were identified in the longitudinal plane using point-of-care ultrasound. With the patient's neck in a neutral position, the level of the proximal (cephalad) margin of the saline-filled cuff of the endotracheal tube was identified and recorded in relationship to the cricoid and tracheal rings. The ideal position is defined as the cephalad margin of the endotracheal tube cuff below the level of the cricoid. RESULTS: The study cohort included 80 patients, ranging in age from 1 to 78 months. In all patients, the cuff of the ETT, cricoid, and tracheal rings were identified. The cephalad end of the endotracheal tube cuff was found at the level of the cricoid in 16.3% of patients, at the first tracheal ring in 27.5% of patients, at the second tracheal ring in 23.8% of patients, at the third tracheal ring in 17.5% of patients, and at below the fourth tracheal ring in 15% of patients. Initial endotracheal tube cuff position had no significant association with age, height, weight, endotracheal tube size, and endotracheal tube type. CONCLUSION: Point-of-care ultrasound provides a rapid and effective means of identifying the position of the endotracheal tube cuff in relationship to the cricoid ring. The technique may have applications in the perioperative arena, emergency departments, and intensive care units.

Intraoperative Management of a Child Undergoing Cardiac Surgery With Congenital Methemoglobinemia Detected in the Operating Room: A Case Report.

Congenital methemoglobinemia is a rare disease that is easily overlooked in its mild form. It can lead to tissue hypoxia as methemoglobin does not possess oxygen-carrying capacity. Its management approach depends on the severity of the symptoms, methemoglobin level, and associated medical conditions. The perioperative management of congenital methemoglobinemia is well described in the literature; however, its management in children with congenital heart disease and undergoing cardiac surgery using cardiopulmonary bypass has not been reported. We present a case and its management where congenital methemoglobinemia was detected in the operating room in a child scheduled for cardiac surgery.

Effect of acoustic standing waves on cellular viability and metabolic activity.

Acoustic standing wave devices offer excellent potential applications in biological sciences for drug delivery, cell manipulation and tissue engineering. However, concerns have been raised about possible destructive effects on cells due to the applied acoustic field, in addition to other produced secondary factors. Here, we report a systematic study employing a 1D resonant acoustic trapping device to evaluate the cell viability and cell metabolism for a healthy cell line (Human Dermal Fibroblasts, HDF) and a cervical cancer cell line (HeLa), as a function of time and voltages applied (4-10 Vpp) under temperature-controlled conditions. We demonstrate that high cell viability can be achieved reliably when the device is operated at its minimum trapping voltage and tuned carefully to maximise the acoustic standing wave field at the cavity resonance. We found that cell viability and reductive metabolism for both cell lines are kept close to control levels at room temperature and at 34 °C after 15 minutes of acoustic exposure, while shorter acoustic exposures and small changes on temperature and voltages, had detrimental effects on cells. Our study highlights the importance of developing robust acoustic protocols where the operating mode of the acoustic device is well defined, characterized and its temperature carefully controlled, for the application of acoustic standing waves when using live cells and for potential clinical applications.

The RNA binding KH domain of Spoonbill depletes pathogenic non-coding spinocerebellar ataxia 8 transcripts and suppresses neurodegeneration in Drosophila.

Spinocerebellar ataxia 8 (SCA8) pathogenesis is a resultant of gain-of-function machinery that primarily results at the RNA level. It has been reported that expanded non-coding CTG trinucleotide repeat in the ATXN8OS transcripts leads to SCA8 coupled neurodegeneration. Targeted depletion of pathogenic SCA8 transcripts is a viable therapeutic approach. In this report we have focused on the suppression of toxic RNA gain-of-function associated with SCA8. We report suppression of SCA8 associated neurodegeneration by KH RNA binding domain of Spoonbill. KH domain suppresses pathogenic SCA8 associated phenotype in adult flies. Ectopic expression of KH domain leads to massive reduction in the number and size of SCA8 RNA foci. We show that Spoonbill interacts with toxic SCA8 transcripts via its KH domain and promotes its depletion. Till date, no attempts have been made for therapeutic intervention of SCA8 pathogenesis. Further characterization of Spoonbill KH domain may aid us in designing peptide based therapeutics for SCA8 associated neurodegeneration.

Bilateral diaphragmatic palsy after congenital heart surgery: management options.

Diaphragmatic paralysis following phrenic nerve injury is a major complication following congenital cardiac surgery. In contrast to unilateral paralysis, patients with bilateral diaphragmatic paralysis present a higher risk group, require different management methods, and have poorer prognosis. We retrospectively analysed seven patients who had bilateral diaphragmatic paralysis following congenital heart surgery during the period from July, 2006 to July, 2014. Considerations were given to the time to diagnosis of diaphragm paralysis, total ventilator days, interval after plication, and lengths of ICU and hospital stays. The incidence of bilateral diaphragmatic paralysis was 0.68% with a median age of 2 months (0.6-12 months). There was one neonate and six infants with a median weight of 4 kg (3-7 kg); five patients underwent unilateral plication of the paradoxical diaphragm following recovery of the other side, whereas the remaining two patients who did not demonstrate a paradoxical movement were successfully weaned from the ventilator following recovery of function in one of the diaphragms. The median ventilation time for the whole group was 48 days (20-90 days). The median length of ICU stay was 46 days (24-110 days), and the median length of hospital stay was 50 days (30-116 days). None of the patients required tracheostomy for respiratory support and there were no mortalities, although all the patients except one developed ventilator-associated pneumonia. The outcome of different management options for bilateral diaphragmatic paralysis following surgery for CHD is discussed.

Selective use of superficial temporal artery cannulation in infants undergoing cardiac surgery.

Arterial cannulation is routinely performed in children undergoing cardiac surgery to aid the intraoperative and intensive care management. Most commonly cannulated peripheral site in children is radial artery, and alternatives include posterior tibial, dorsalis pedis, and rarely superficial temporal artery (STA). Two specific situations in cardiac surgery where STA cannulation and monitoring was useful during the surgical procedure are reported. To our knowledge, such selective use of STA pressure monitoring has not been reported in the literature previously. Our experience suggests that STA monitoring can be useful and reliable during repair of coarctation of aorta or administration of anterograde cerebral perfusion in patients having associated aberrant origin of the right subclavian artery.

Regulation of Notch Signaling by an Evolutionary Conserved DEAD Box RNA Helicase, Maheshvara in Drosophila melanogaster.

Notch signaling is an evolutionary conserved process that influences cell fate determination, cell proliferation, and cell death in a context-dependent manner. Notch signaling is fine-tuned at multiple levels and misregulation of Notch has been implicated in a variety of human diseases. We have characterized maheshvara (mahe), a novel gene in Drosophila melanogaster that encodes a putative DEAD box protein that is highly conserved across taxa and belongs to the largest group of RNA helicase. A dynamic pattern of mahe expression along with the maternal accumulation of its transcripts is seen during early stages of embryogenesis. In addition, a strong expression is also seen in the developing nervous system. Ectopic expression of mahe in a wide range of tissues during development results in a variety of defects, many of which resemble a typical Notch loss-of-function phenotype. We illustrate that ectopic expression of mahe in the wing imaginal discs leads to loss of Notch targets, Cut and Wingless. Interestingly, Notch protein levels are also lowered, whereas no obvious change is seen in the levels of Notch transcripts. In addition, mahe overexpression can significantly rescue ectopic Notch-mediated proliferation of eye tissue. Further, we illustrate that mahe genetically interacts with Notch and its cytoplasmic regulator deltex in trans-heterozygous combination. Coexpression of Deltex and Mahe at the dorso-ventral boundary results in a wing-nicking phenotype and a more pronounced loss of Notch target Cut. Taken together we report identification of a novel evolutionary conserved RNA helicase mahe, which plays a vital role in regulation of Notch signaling.

Use of high-frequency ventilation to wean off cardiopulmonary bypass in a patient with pulmonary hemorrhage after failure of conventional ventilation.

The management of an infant who underwent corrective surgery for a supracardiac total anomalous pulmonary venous drainage, which was complicated by the development of pulmonary hemorrhage while separating from cardiopulmonary bypass, is presented. Initiation of high-frequency oscillatory ventilation was effective in weaning the patient off cardiopulmonary bypass.

MTHFR C677T predisposes to POAG but not to PACG in a North Indian population: a case control study.

Hyperhomocysteinemia induced by the C677T genetic variant in MTHFR (methylenetetrahydrofolate reductase) has been implicated in neuronal cell death of retinal ganglion cells (RGC), which is a characteristic feature of glaucoma. However, association of MTHFR C677T with glaucoma has been controversial because of inconsistent results across association studies. Association between MTHFR C677T and glaucoma has not been reported in Indian population. Therefore, with a focus on neurodegenerative death of RGC in glaucoma, the current study aimed to investigate association of MTHFR C677T with Primary Open Angle Glaucoma (POAG) and Primary Angle Closure Glaucoma (PACG) in a North Indian population. A total of 404 participants (231 patients and 173 controls) were included in this study. Genotyping was performed by Polymerase Chain Reaction-Restriction Fragment Length Polymorphism. A few random samples were also tested by direct sequencing. Genotypic and allelic distributions of the POAG and PACG cohorts were compared to that of controls by chi-square test and odds ratios were reported with 95% confidence intervals. Genotypic and allelic distributions between POAG cases and controls were significantly different (p = 0.03 and p = 0.01 respectively). Unlike POAG, we did not find significant difference in the genotypic and allelic distributions of C677T between PACG cases and controls (p>0.05). We also observed a higher proportion of TT associated POAG in females than that in males. However, this is a preliminary indication of gender specific risk of C677T that needs to be replicated in a larger cohort of males and females. The present investigation on MTHFR C677T and glaucoma reveals that the TT genotype and T allele of this polymorphism are significant risk factors for POAG but not for PACG in North Indian population. Ours is the first report demonstrating association of MTHFR C677T with POAG but not PACG in individuals from North India.

dLin52 is crucial for dE2F and dRBF mediated transcriptional regulation of pro-apoptotic gene hid.

Drosophila lin52 (dlin52) is a member of Myb transcription regulator complex and it shows a dynamic pattern of expression in all Drosophila tissues. Myb complex functions to activate or repress transcription in a site-specific manner; however, the detailed mechanism is yet to be clearly understood. Members of the Drosophila melanogaster Myb-MuvB/dREAM complex have been known to regulate expression of a wide range of genes including those involved in regulating apoptosis. E2F and its corepressor RBF also belong to this complex and together they regulate expression of genes involved in cell cycle progression, apoptosis, differentiation, and development. In the present study, we examined whether the depletion of dlin52 in developing photoreceptor neurons results in enhanced apoptosis and disorganisation of the ommatidia. Strikingly, we found that dLin52 is essential for transcriptional repression of the pro-apoptotic gene, hid; decrease in dlin52 levels led to dramatic induction of hid and apoptosis in eye-antennal discs. Reduction of Rpd3 (HDAC1), another member of the dREAM complex, also led to marginal upregulation of Hid. In addition, we also demonstrated that an optimum level of dLin52 is needed for dE2F1/2 activity on the hid promoter. dlin52 cooperates with dRBF and dE2F1/2 for recruitment of repressor complex on the hid promoter. Preliminary data indicate that Rpd3/HDAC1 also contributes to hid repression. Based on the findings, we conclude that dLin52 functions as a co-factor and modulates activity of members of dMyb/dREAM complex at hid promoter, thus regulating apoptosis by repressing this pro-apoptotic gene in the developing Drosophila eye.

Anesthetic management of an infant with Joubert syndrome for cardiac surgery.

The anesthetic implications of Joubert syndrome in an infant who required cardiac surgery using cardiopulmonary bypass (CPB) is presented. Children with Joubert syndrome present with central apnea due to malformations in the midbrain and cerebellum. These patients have a marked sensitivity to opioids. The use of dexmedetomidine along with remifentanil was effective in this case.

Further insights into the syndrome of prolapsing non-coronary aortic cusp and ventricular septal defect.

Ventricular septal defect (VSD) with prolapse of the right coronary cusp and aortic regurgitation can be managed surgically with the anatomical correction technique. However when the VSD is located underneath the non coronary cusp surgical management differs due to anatomical constraints and secondary pathological changes seen in the non coronary cusp. It is therefore important that the location of the VSD and the morphology of prolapsing cusp be characterised preoperatively in order to plan appropriate surgical repair. We present a case study in which we discuss the salient differences in the surgical management of the prolapsing right and the prolapsing non coronary cusps.

Dynamic pattern of expression of dlin52, a member of the Myb/MuvB complex, during Drosophila development.

The DREAM (DP, RB, E2F and MuvB) complex is required in humans to arrest the expression of cell cycle genes during quiescence. One of its members LIN52 has been isolated from the repressor complex but little is known about its molecular function. It has been reported recently that the serine residue 28 of LIN52 is phosphorylated by DYRK1A, and point mutation of this residue or down regulation of DYRK1A (which phosphorylates LIN52) leads to disruption of DREAM complex assembly, which is needed for G(0) arrest. Function of all the members of the dMyb complex (homologue of DREAM complex) in Drosophila melanogaster is not well characterized. We have studied the Drosophila orthologue of LIN52, known as dlin52, which is strongly conserved across various taxa from worms to human. dlin52 is reported to be present in a large protein complex containing important transcriptional regulators of cell proliferation and cell death like dE2F1, dMyb and dRbf. We have examined the expression of dlin52 transcripts and protein during development. Strong nuclear expression of dlin52 is seen in larval eye-antennal discs, brain, fat body, wing discs and salivary glands. dlin52 is abundantly expressed in endoreplicated tissues like salivary glands, fat body, and certain regions of the gut, and the nurse cells from adult ovaries. dlin52 is also expressed in the larval optic lobe, as well as in the developing neurons of ventral ganglion, indicating that this gene has an important role to play in cell cycle regulation and neuronal development. Robust expression of dlin52 protein was observed in quiescent cells like that of the imaginal cells of larval salivary gland, while marginal expression was seen in the germarium of adult ovary. Study of the spatial and temporal pattern of expression of this gene will help in better understanding of the function of this protein during various developmental processes.