The phenomenon of autoresuscitation is rare, yet it is known to most emergency physicians. However, the pathophysiology of the delayed return of spontaneous circulation remains enigmatic. Among other ...causes hyperinflation of the lungs and excessively high positive end-expiratory pressure have been suggested, but reports including cardiopulmonary monitoring during cardiopulmonary resuscitation are scarce to support this hypothesis.
We report a case of autoresuscitation in a 44-year-old white man after 80 minutes of advanced cardiac life support accompanied by continuous capnometry and repeated evaluation by ultrasound and echocardiography. After prolonged cardiopulmonary resuscitation, refractory electromechanical dissociation on electrocardiogram and ventricular akinesis were recorded. In addition, a precipitous drop in end-tidal partial pressure of carbon dioxide was noted and cardiopulmonary resuscitation was discontinued. Five minutes after withdrawal of all supportive measures his breathing resumed and a perfusing rhythm ensued.
Understanding the underlying pathophysiology of autoresuscitation is hampered by a lack of reports including extensive cardiopulmonary monitoring during cardiopulmonary resuscitation in a preclinical setting. In this case, continuous capnometry was combined with repetitive ultrasound evaluation, which ruled out most assumed causes of autoresuscitation. Our observation of a rapid decline in end-tidal partial pressure of carbon dioxide supports the hypothesis of increased intrathoracic pressure. Continuous capnometry can be performed easily during cardiopulmonary resuscitation, also in a preclinical setting. Knowledge of the pathophysiologic mechanisms may lead to facile interventions to be incorporated into cardiopulmonary resuscitation algorithms. A drop in end-tidal partial pressure of carbon dioxide, for example, might prompt disconnection of the ventilation to allow left ventricular filling. Further reports and research on this topic are encouraged.
Diseases of the kidney filtration barrier are a leading cause of ESRD. Most disorders affect the podocytes, polarized cells with a limited capacity for self-renewal that require tightly controlled ...signaling to maintain their integrity, viability, and function. Here, we provide an atlas of in vivo phosphorylated, glomerulus-expressed proteins, including podocyte-specific gene products, identified in an unbiased tandem mass spectrometry-based approach. We discovered 2449 phosphorylated proteins corresponding to 4079 identified high-confidence phosphorylated residues and performed a systematic bioinformatics analysis of this dataset. We discovered 146 phosphorylation sites on proteins abundantly expressed in podocytes. The prohibitin homology domain of the slit diaphragm protein podocin contained one such site, threonine 234 (T234), located within a phosphorylation motif that is mutated in human genetic forms of proteinuria. The T234 site resides at the interface of podocin dimers. Free energy calculation through molecular dynamic simulations revealed a role for T234 in regulating podocin dimerization. We show that phosphorylation critically regulates formation of high molecular weight complexes and that this may represent a general principle for the assembly of proteins containing prohibitin homology domains.
Following genotoxic stress, cells activate a complex signalling network to arrest the cell cycle and initiate DNA repair or apoptosis. The tumour suppressor p53 lies at the heart of this DNA damage ...response. However, it remains incompletely understood, which signalling molecules dictate the choice between these different cellular outcomes. Here, we identify the transcriptional regulator apoptosis‐antagonizing transcription factor (AATF)/Che‐1 as a critical regulator of the cellular outcome of the p53 response. Upon genotoxic stress, AATF is phosphorylated by the checkpoint kinase MK2. Phosphorylation results in the release of AATF from cytoplasmic MRLC3 and subsequent nuclear translocation where AATF binds to the PUMA, BAX and BAK promoter regions to repress p53‐driven expression of these pro‐apoptotic genes. In xenograft experiments, mice exhibit a dramatically enhanced response of AATF‐depleted tumours following genotoxic chemotherapy with adriamycin. The exogenous expression of a phospho‐mimicking AATF point mutant results in marked adriamycin resistance in vivo. Nuclear AATF enrichment appears to be selected for in p53‐proficient endometrial cancers. Furthermore, focal copy number gains at the AATF locus in neuroblastoma, which is known to be almost exclusively p53‐proficient, correlate with an adverse prognosis and reduced overall survival. These data identify the p38/MK2/AATF signalling module as a critical repressor of p53‐driven apoptosis and commend this pathway as a target for DNA damage‐sensitizing therapeutic regimens.
DNA damage activates the tumour suppressor p53, resulting in either cell‐cycle arrest or apoptosis. One mechanism that selectively represses apoptosis‐promoting genes involves phosphorylation of the transcription factor AATF/Che‐1 by the p38‐activated kinase MK2.
The anti-angiogenic factor sFlt-1 is the main candidate in the progression of preeclampsia, a disease which causes placental dysfunctions often leading to IUGR. Mostly is known about the impairment ...of the endothelial cell function by sFlt-1, but how sFlt-1 leads to IUGR and affects the placenta and fetus is currently unknown as well as therapeutic agents against such diseases are missing.
Therefore we have established two transgenic, inducible sFlt-1 mouse models: (1) maternal ubiquitous (sFlt-1/rtTA mice) and (2) placental (sFlt-1/tTA/TpbpaCre mice) overexpression of human sFlt-1. We hypothesize that sFlt-1 is involved in the development of IUGR by influencing placental development and function and is therefore a potential candidate for intervention strategies.
We examined the effects of sFlt-1 on placental morphology and function at 18.5 dpc with morphometric and immunohistochemical analyses and transcript expression of placental marker genes, nutrient transporters and proteomic analyses.
Ubiquitous overexpression of sFlt-1 led to IUGR of the fetuses as shown by reduced fetal weights and signs of retardation. In addition, we observed a severely impaired placental phenotype shown by enlarged maternal blood sinusoids, a reduced number of fetal vessels and an inadequate placental differentiation of the labyrinth. Glucose, fatty acid and amino acid transport seem to be negatively affected. Preliminary results of the placental overexpression of sFlt-1 revealed while expressing lower levels of sFlt-1 also IUGR.
We assume that sFlt-1 has an inhibitory effect on placental differentiation, especially on fetal vessel development. A possible reactive response could be an increase in maternal blood flow promoting dilatation of the maternal sinusoids to fulfil the nutrient requirements of the fetus. This ultimately resulted in an uteroplacental insufficiency leading to IUGR. Thus, we speculate that the alterations triggered by increased anti-angiogenesis upon sFlt-1 strongly may affect fetal outcome and programming.
Background
Steroid-resistant nephrotic syndrome (SRNS) is a severe cause of progressive renal disease. Genetic forms of SRNS can present with autosomal recessive or autosomal dominant inheritance. ...Recent studies have identified mutations in multiple podocyte genes responsible for SRNS. Improved sequencing methods (next-generation sequencing, NGS) now promise rapid mutational testing of SRNS genes.
Methods
In the present study, a simultaneous screening of ten SRNS genes in 37 SRNS patients was performed by NGS.
Results
In 38 % of the patients, causative mutations in one SRNS gene were found. In 22 % of the patients, in addition to these mutations, a secondary variant in a different gene was identified.
Conclusions
This high incidence of accumulating sequence variants was unexpected but, although they might have modifier effects, the pathogenic potential of these additional sequence variants seems unclear so far. The example of molecular diagnostics by NGS in SRNS patients shows that these new sequencing technologies might provide further insight into molecular pathogenicity in genetic disorders but will also generate results, which will be difficult to interpret and complicate genetic counseling. Although NGS promises more frequent identification of disease-causing mutations, the identification of causative mutations, the interpretation of incidental findings and possible pitfalls might pose problems, which hopefully will decrease by further experience and elucidation of molecular interactions.
Abstract
Chronic alterations in calcium (Ca
2+
) signalling in podocytes have been shown to cause proteinuria and progressive glomerular diseases. However, it is unclear whether short Ca
2+
peaks ...influence glomerular biology and cause podocyte injury. Here we generated a
DREADD
(Designer Receptor Exclusively Activated by a Designer Drug) knock-in mouse line to manipulate intracellular Ca
2+
levels. By mating to a podocyte-specific Cre driver we are able to investigate the impact of Ca
2+
peaks on podocyte biology in living animals. Activation of the engineered G-protein coupled receptor with the synthetic compound clozapine-N-oxide (CNO) evoked a short and transient Ca
2+
peak in podocytes immediately after CNO administration
in vivo
. Interestingly, this Ca
2+
peak did neither affect glomerular perfusion nor filtration in the animals. Moreover, no obvious alterations in the glomerular morphology could be observed. Taken together, these
in vivo
findings suggest that chronic alterations and calcium overload rather than an induction of transient Ca
2+
peaks contribute to podocyte disease.
Chronic alterations in calcium (Ca
) signalling in podocytes have been shown to cause proteinuria and progressive glomerular diseases. However, it is unclear whether short Ca
peaks influence ...glomerular biology and cause podocyte injury. Here we generated a DREADD (Designer Receptor Exclusively Activated by a Designer Drug) knock-in mouse line to manipulate intracellular Ca
levels. By mating to a podocyte-specific Cre driver we are able to investigate the impact of Ca
peaks on podocyte biology in living animals. Activation of the engineered G-protein coupled receptor with the synthetic compound clozapine-N-oxide (CNO) evoked a short and transient Ca
peak in podocytes immediately after CNO administration in vivo. Interestingly, this Ca
peak did neither affect glomerular perfusion nor filtration in the animals. Moreover, no obvious alterations in the glomerular morphology could be observed. Taken together, these in vivo findings suggest that chronic alterations and calcium overload rather than an induction of transient Ca
peaks contribute to podocyte disease.
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