An Unusual Cause of Irritability in a Single Ventricle Patient after Bidirectional Glenn Shunt

The differential diagnosis for irritability in children is broad. In patients with congenital heart disease, one must strongly consider cardiac etiologies such as low cardiac output or elevated central venous pressure (CVP). In patients with single-ventricle physiology, the second stage of palliation includes bidirectional Glenn, which involves anastomosis of the superior vena cava to the pulmonary artery resulting in volume offloading of the single systemic ventricle. Typically, early in the post-operative period, patients may experience a headache due to the acute increase in CVP, and symptoms improve over time. Idiopathic intracranial hypertension (IIH), also known as pseudotumor cerebri, is a rare neurologic disorder in children, characterized by raised intracranial pressure (ICP) in the absence of brain parenchymal lesions or cerebrospinal fluid (CSF) abnormalities. While the pathogenesis of IIH is unknown, early recognition and treatment of IIH are important to prevent permanent vision loss. There are only rare reports of IIH in patients with Fontan circulation. To our knowledge, we report the first case of IIH in a 2-year-old female after bidirectional Glenn.     

Thioredoxin is required for filamentous phage assembly.

Sequence comparisons show that the fip gene product of Escherichia coli, which is required for filamentous phage assembly, is thioredoxin. Thioredoxin serves as a cofactor for reductive processes in many cell types and is a constituent of phage T7 DNA polymerase. The fip-1 mutation makes filamentous phage and T7 growth temperature sensitive in cells that carry it. The lesion lies within a highly conserved thioredoxin active site. Thioredoxin reductase (NADPH), as well as thioredoxin, is required for efficient filamentous phage production. Mutant phages defective in phage gene I are particularly sensitive to perturbations in the fip-thioredoxin system. A speculative model is presented in which thioredoxin reductase, thioredoxin, and the gene I protein interact to drive an engine for filamentous phage assembly.     

Melatonin and its atheroprotective effects: A review

Atherosclerosis is a chronic vascular disease in which oxidative stress and inflammation are commonly implicated as major causative factors. Identification of novel strategies that contribute to plaque stabilization or inhibition represents a continuing challenge for the medical community.     

Delivery of pineal melatonin to the brain and SCN: role of canaliculi,cerebrospinal fluid,tanycytes and Virchow–Robin perivascular spaces

Historically, the direct release of pineal melatonin into the capillary bed within the gland has been accepted as the primary route of secretion. Herein, we propose that the major route of melatonin delivery to the brain is after its direct release into the cerebrospinal fluid (CSF) of the third ventricle (3V). Melatonin concentrations in the CSF are not only much higher than in the blood, also, there is a rapid nocturnal rise at darkness onset and precipitous decline of melatonin levels at the time of lights on. Because melatonin is a potent free radical scavenger and antioxidant, we surmise that the elevated CSF levels are necessary to combat the massive free radical damage that the brain would normally endure because of its high utilization of oxygen, the parent molecule of many toxic oxygen metabolites, i.e., free radicals. Additionally, the precise rhythm of CSF melatonin provides the master circadian clock, the suprachiasmatic nucleus, with highly accurate chronobiotic information regarding the duration of the dark period. We predict that the discharge of melatonin directly into the 3V is aided by a number of epithalamic structures that have heretofore been overlooked; these include interpinealocyte canaliculi and evaginations of the posterodorsal 3V that directly abut the pineal. Moreover, the presence of tanycytes in the pineal recess and/or a discontinuous ependymal lining in the pineal recess allows melatonin ready access to the CSF. From the ventricles melatonin enters the brain by diffusion and by transport through tanycytes. Melatonin-rich CSF also circulates through the aqueduct and eventually into the subarachnoid space. From the subarachnoid space surrounding the brain, melatonin penetrates into the deepest portions of the neural tissue via the Virchow–Robin perivascular spaces from where it diffuses into the neural parenchyma. Because of the high level of pineal-derived melatonin in the CSF, all portions of the brain are better shielded from oxidative stress resulting from toxic oxygen derivatives.     

Melatonin promotes the in vitro development of pronuclear embryos and increases the efficiency of blastocyst implantation in murine

When a defect occurs in the in vitro development of a pronuclear embryo, the interruption of the subsequent implantation limits the success of assisted conception. This common problem remains to be solved. In this study, we observed that melatonin at its physiological concentration (10^?7 m ) significantly promoted the in vitro development of murine pronuclear embryos. This was indicated by the increased blastocyst rate, hatching blastocyst rate, and blastocyst cell number with melatonin treatment. In addition, when these blastocysts were implanted into female recipient mice, the pregnancy rates (95.0% versus control 67.8%), litter sizes (4.1 pups/litter versus control 2.7 pups/litter), and postnatal survival rates of offspring (96.84% versus control 81.24%) were significantly improved compared with their non‐melatonin‐treated counterparts. Mechanistic studies revealed that melatonin treatment upregulates gene expression of the antioxidant enzyme, superoxide dismutase (SOD), and the anti‐apoptotic factor bcl‐2 while downregulating the expression of pro‐apoptotic genes p53 and caspase‐3. Due to these changes, melatonin treatment reduces ROS production and cellular apoptosis during in vitro embryo development and improves the quality of blastocysts. The implantation of blastocysts with higher quality leads to more healthy offspring and increased pup survival.     

Visualization of melatonin's multiple mitochondrial levels of protection against mitochondrial Ca2+-mediated permeability transition and beyond in rat brain astrocytes

Abstract: Melatonin protects cells against various types of oxidative stress‐induced apoptosis due primarily to its ability to effectively scavenge pathological and disease condition‐augmented generation of mitochondrial reactive oxygen species (mROS). Once produced, mROS indiscriminately damage mitochondrial components and more importantly they crucially activate directly the mitochondrial permeability transition (MPT), one of the critical mechanisms for initiating post mitochondrial apoptotic signaling. Whether or not melatonin targets directly the MPT, however, remains inconclusive, particularly during oxidative stress. This study, thus, investigated this possibility of an ‘oxidation free Ca²⁺ stress’ in the presence of vitamin E after ionomycin exposure as a sole Ca²⁺‐mediated MPT in order to exclude melatonin’s primary antioxidative effects as well as Ca²⁺‐mediated oxidative stress. The studies were carried out using cultured rat brain astrocytes RBA‐1. With the application of laser scanning multiple fluorescence imaging microscopy, we visualized for the first time multiple mitochondrial protective effects provided by melatonin during Ca²⁺ stress. First, melatonin, due to its primary antioxidative actions, completely prevented mCa²⁺‐induced mROS formation during ionomycin exposure. Secondly, when melatonin^’s antioxidative effects were prevented due to the addition of vitamin E, melatonin significantly prevented mCa²⁺‐mediated MPT and apoptosis suggesting its direct targeting of the MPT. Surprisingly, in the presence of cyclosporin A, a MPT inhibitor, melatonin reduced further mCa²⁺‐mediated apoptosis during ionomycin exposure also suggesting its targeting beyond the MPT. As astrocytes are actively involve in regulating synaptic transmission and neurovascular coupling in the CNS, these multiple mitochondrial layers of protection provided by melatonin against mCa²⁺‐and/or mROS‐mediated apoptosis in astrocytes may be crucial for future therapeutic prevention and treatment of astrocyte‐mediated neurodegenerative diseases in the CNS.     

Melatonin resynchronizes dysregulated circadian rhythm circuitry in human prostate cancer cells

Abstract: Prostate cancer (PCa) is a major age‐related malignancy as increasing age correlates with increased risk for developing this neoplasm. Similarly, alterations in circadian rhythms have also been associated with the aging population and cancer risk. The pineal hormone melatonin is known to regulate circadian rhythms, which is under the control of a core set of genes: Period 1, 2, 3 (Per 1–3); Cryptochrome 1, 2 (Cry 1, 2); Clock, and Bmal 1, 2. Melatonin levels have been shown to decrease in patients with cancer and exogenous melatonin exhibits antiproliferative effects against certain cancers. In this study, we challenged the hypothesis that melatonin imparts antiproliferative effects in prostate cancer via resynchronization of deregulated core clock circuitry. We found that Clock and Per2 protein levels were downregulated whereas Bmal1 protein levels were upregulated in PCa cells, compared to normal prostate cells. Additionally, employing automated quantitative analysis of a microarray containing human tissues, we found that compared to benign tissues, Clock and Per2 levels were downregulated, whereas Bmal1 levels were upregulated in PCa and other proliferative prostatic conditions. Overexpression of Per2 was found to result in a significant loss of PCa cell growth and viability. Interestingly, melatonin treatment resulted in an increase in Per2 and Clock and a reduction in Bmal1 in PCa cells. Further, melatonin treatment resulted in a resynchronization of oscillatory circadian rhythm genes (Dbp and Per2). Our data support our hypothesis and suggest that melatonin should be thoroughly investigated as an agent for the management of PCa and other age‐related malignancies.     

Fenestrated ASD Closure in a Child with Idiopathic Pulmonary Hypertension and Exercise Desaturation

Pulmonary arterial hypertension is a progressive disorder that may result in right heart failure and death. Atrial level shunts in the presence of pulmonary hypertension may allow right‐to‐left mixing with maintenance of cardiac output and improved survival. However, excessive mixing at the atrial level can cause undue systemic desaturation, increased fatigue and decreased exercise tolerance even in the presence of adequate cardiac output. A 5½‐year‐old was diagnosed with pulmonary hypertension, a large atrial septal defect and right‐to‐left shunting. Medical therapy over an 18‐month period was successful in decreasing pulmonary artery pressure and pulmonary vascular resistance. However, because of the size and position of the intracardiac defect, symptoms of fatigue, and severe systemic desaturation with only minor activities persisted. Fenestrated surgical closure of the defect was thus undertaken to decrease the degree of atrial mixing, but still allow atrial decompression if necessary. Subsequent hemodynamic evaluation has demonstrated continued improvement, and all previous symptoms have resolved. Repeated echocardiography has confirmed patency of the atrial fenestration with left‐to‐right atrial flow.     

The added value of real-time three-dimensional echocardiography in the diagnosis of supravalvar mitral ring: case report and review of the literature

Supravalvular mitral stenosis is a rare condition characterized by an abnormal ridge, with one or two orifices, covering and obstructing the mitral valve. Preoperative identification of the supravalvular ring is the target for obtaining good surgical results. Two-dimensional echocardiogram and transesophageal echocardiography both failed in reaching this objective. In this case, we showed that three-dimensional echocardiogram is a new technique that provides additional and more accurate echocardiographic characterization of congenital supravalvular mitral stenosis.