A Rare Neurological Presentation of Noonan Syndrome and Its Management-A Case Report.

Although Noonan syndrome is a relatively common congenital disorder with autosomal dominant inheritance, its association with cerebrovascular anomalies is rare. We report a case of a 20-year-old with Noonan syndrome with cerebrovascular aneurysm, who underwent successful endovascular coiling. Only four cases of cerebrovascular aneurysms in Noonan syndrome have been reported in the literature so far. To the best of our knowledge, this is only the fifth reported case and the first one that has been treated successfully with endovascular coiling. We hereby discuss the management of this case, which had several comorbidities like congenital heart disease and craniovertebral junction anomaly.

The Role of Serum Matrix Metalloproteinase-9 as a Predictor of Delayed Cerebral Ischemia in Patients with Aneurysmal Subarachnoid Hemorrhage.

Delayed cerebral ischemia (DCI) is one of the major causes of a poor neurological outcome following aneurysmal subarachnoid hemorrhage (aSAH). Several biomarkers, including matrix metalloproteinase-9 (MMP-9), have been evaluated to predict the development of DCI for timely management. This prospective cohort study was done on 98 patients with aSAH presenting within 72 h of the ictus. Serum samples were collected preoperatively, 7 days after ictus, 10 days after ictus, or when the patient developed DCI, whichever was earlier. The primary objective was to correlate the serum MMP-9 levels with the development of DCI. The secondary objectives were to correlate the serum MMP-9 levels with sonographic vasospasm and the neurological outcome. There was no correlation between the serum MMP-9 levels and the development of DCI (p = 0.37). Similarly, there was no correlation between the serum MMP-9 levels and the sonographic vasospasm (0.05) nor with the modified Rankin Scale (mRS) at discharge (p = 0.27), mRS at 3 months (p = 0.22), and Glasgow Outcome Scale Extended (GOSE) at 3 months (p = 0.15). Serum MMP-9 levels do not predict the development of DCI following aSAH.

Comparison of Ultrasound Parameters and Clinical Parameters in Airway Assessment for Prediction of Difficult Laryngoscopy and Intubation: An Observational Study.

Background and objective The primary responsibility of the anesthesiologist is to provide adequate oxygenation and ventilation to the patient by securing the airway. Prediction of Cormack-Lehane (CL) grading preoperatively helps patients' airway management during anesthesia induction, particularly in difficult intubations. Our study aims to evaluate airway assessment modalities using ultrasound and conventional clinical screening methods for predicting difficult laryngoscopy and intubation. Materials and methods This prospective observational study was conducted on 100 patients aged between 18 and 70 years belonging to ASA classes I, II, and III scheduled for elective surgery requiring general anesthesia under endotracheal intubation was included in the study. Patients who needed rapid sequence induction and had a history of difficult intubation, obese patients with a body mass index (BMI) of more than 40, patients with notable swelling in the neck region (thyroid), pregnant patients, and patients with maxillofacial anomalies were excluded from the study. Clinical parameters such as body mass index, neck circumference, modified Mallampati grading, thyromental distance, and ultrasound parameters such as anterior neck soft tissue thickness at the level of the thyrohyoid membrane (ANS-TM) and anterior neck soft tissue thickness at the level of vocal cord (ANS-VC) were obtained preoperatively. After intubation, the CL grading was noted and categorized into two groups: easy (classes 1 and 2) and difficult (classes 3 and 4). Descriptive statistics included frequency and percentage for categorical variables and mean±standard deviation for continuous variables. The chi-square test was applied to find the relationship between easy and difficult laryngoscopy when compared with the outcome for categorical variables. A P value of less than 0.05 was considered significant throughout the study. The receiver operating characteristics curve (ROC curve) was used to determine the sensitivity and specificity to predict the outcomes. Results Ultrasound-guided measurements of ANS-TM and ANS-VC are independent predictors of difficult laryngoscopy compared with clinical screening tests. Of the two parameters, we found that ANS-TM has a better diagnostic value for predicting a difficult airway with an area under the ROC curve (AUC) of 91% compared with ANS-VC, which has an AUC of 84%. Of the clinical parameters, the modified Mallampati grading has an AUC of 81%, leading to better diagnostic value in the prediction of a difficult airway. Conclusion Our study demonstrated that ANS-TM and ANS-VC are independent predictors of a difficult airway. ANS-TM has a better correlation with CL grading. Clinical screening tests should be combined with ultrasound measurements to aid in the better prediction of difficult laryngoscopy.

Anesthetic Considerations for a Patient with Autosomal Dominant Polycystic Kidney Disease, Having a Ruptured Intracranial Aneurysm for Endovascular Coiling: A Case Report.

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic disorder affecting 1 in 1,000 people worldwide. Intracranial aneurysms are an important extrarenal complication with a prevalence of 9 to 12%. The definitive management of an aneurysm includes surgical clipping or endovascular coiling. There is a paucity of literature regarding the anesthetic management of such patients. The pre-existing renal condition is an additional challenge in the management of these patients as the complications associated with chronic kidney disease are superimposed on those due to subarachnoid hemorrhage. Here, we describe anesthetic management of a patient with ADPKD who had a ruptured anterior communicating artery aneurysm, for which endovascular coiling was done.

Chromosome-Level Genome Sequence of Leishmania (Leishmania) tropica Strain CDC216-162, Isolated from an Afghanistan Clinical Case.

PacBio and Illumina MiSeq platforms were used for genomic sequencing of a Leishmania (Leishmania) tropica strain isolated from a patient infected in Pakistan. PacBio assemblies were generated using Flye v2.4 and polished with MiSeq data. The results represent a considerable improvement of the currently available genome sequences in the GenBank database.

Draft Genome Sequences of Leishmania (Leishmania) amazonensis, Leishmania (Leishmania) mexicana, and Leishmania (Leishmania) aethiopica, Potential Etiological Agents of Diffuse Cutaneous Leishmaniasis.

We present here the draft genome sequences of Leishmania (Leishmania) amazonensis, Leishmania (Leishmania) mexicana, and Leishmania (Leishmania) aethiopica, potential etiological agents of diffuse cutaneous leishmaniasis (DCL). Sequence data were obtained using PacBio and MiSeq platforms. The PacBio assemblies generated using Canu v1.6 are more contiguous than are those in the available data.

First Draft Genome Sequence of Leishmania (Viannia) lainsoni Strain 216-34, Isolated from a Peruvian Clinical Case.

We present here the first draft genome sequence of Leishmania (Viannia) lainsoni strain 216-34, sequenced using PacBio and MiSeq platforms. PacBio contigs were generated from de novo assemblies using CANU version 1.6 and polished using Illumina reads.

Friedreich's ataxia (GAA)n•(TTC)n repeats strongly stimulate mitotic crossovers in Saccharomyces cerevisae.

Expansions of trinucleotide GAA•TTC tracts are associated with the human disease Friedreich's ataxia, and long GAA•TTC tracts elevate genome instability in yeast. We show that tracts of (GAA)(230)•(TTC)(230) stimulate mitotic crossovers in yeast about 10,000-fold relative to a "normal" DNA sequence; (GAA)(n)•(TTC)(n) tracts, however, do not significantly elevate meiotic recombination. Most of the mitotic crossovers are associated with a region of non-reciprocal transfer of information (gene conversion). The major class of recombination events stimulated by (GAA)(n)•(TTC)(n) tracts is a tract-associated double-strand break (DSB) that occurs in unreplicated chromosomes, likely in G1 of the cell cycle. These findings indicate that (GAA)(n)•(TTC)(n) tracts can be a potent source of loss of heterozygosity in yeast.

Large-scale expansions of Friedreich's ataxia GAA repeats in yeast.

Large-scale expansions of DNA repeats are implicated in numerous hereditary disorders in humans. We describe a yeast experimental system to analyze large-scale expansions of triplet GAA repeats responsible for the human disease Friedreich's ataxia. When GAA repeats were placed into an intron of the chimeric URA3 gene, their expansions caused gene inactivation, which was detected on the selective media. We found that the rates of expansions of GAA repeats increased exponentially with their lengths. These rates were only mildly dependent on the repeat's orientation within the replicon, whereas the repeat-mediated replication fork stalling was exquisitely orientation dependent. Expansion rates were significantly elevated upon inactivation of the replication fork stabilizers, Tof1 and Csm3, but decreased in the knockouts of postreplication DNA repair proteins, Rad6 and Rad5, and the DNA helicase Sgs1. We propose a model for large-scale repeat expansions based on template switching during replication fork progression through repetitive DNA.

Chromosome fragility at GAA tracts in yeast depends on repeat orientation and requires mismatch repair.

Expansion of triplex-forming GAA/TTC repeats in the first intron of FXN gene results in Friedreich's ataxia. Besides FXN, there are a number of other polymorphic GAA/TTC loci in the human genome where the size variations thus far have been considered to be a neutral event. Using yeast as a model system, we demonstrate that expanded GAA/TTC repeats represent a threat to eukaryotic genome integrity by triggering double-strand breaks and gross chromosomal rearrangements. The fragility potential strongly depends on the length of the tracts and orientation of the repeats relative to the replication origin, which correlates with their propensity to adopt triplex structure and to block replication progression. We show that fragility is mediated by mismatch repair machinery and requires the MutSbeta and endonuclease activity of MutLalpha. We suggest that the mechanism of GAA/TTC-induced chromosomal aberrations defined in yeast can also operate in human carriers with expanded tracts.

Replication stalling at unstable inverted repeats: interplay between DNA hairpins and fork stabilizing proteins.

DNA inverted repeats (IRs) are hotspots of genomic instability in both prokaryotes and eukaryotes. This feature is commonly attributed to their ability to fold into hairpin- or cruciform-like DNA structures interfering with DNA replication and other genetic processes. However, direct evidence that IRs are replication stall sites in vivo is currently lacking. Here, we show by 2D electrophoretic analysis of replication intermediates that replication forks stall at IRs in bacteria, yeast, and mammalian cells. We found that DNA hairpins, rather than DNA cruciforms, are responsible for the replication stalling by comparing the effects of specifically designed imperfect IRs with varying lengths of their central spacer. Finally, we report that yeast fork-stabilizing proteins, Tof1 and Mrc1, are required to counteract repeat-mediated replication stalling. We show that the function of the Tof1 protein at DNA structure-mediated stall sites is different from its previously described effect on protein-mediated replication fork barriers.

Intrachromosomal gene amplification triggered by hairpin-capped breaks requires homologous recombination and is independent of nonhomologous end-joining.

Gene amplification is one of the major mechanisms of acquisition of drug resistance and activation of oncogenes in tumors. In mammalian cells, amplified chromosomal regions are manifested cytogenetically as extrachromosomal double minutes (DMs) and chromosomal homogeneously staining regions (HSRs). We recently demonstrated using yeast model system that hairpin-capped double strand breaks (DSBs) generated at the location of human Alu-quasipalindromes can trigger both types of gene amplification. Specifically, the dicentric chromosomes arising from replication of hairpin-capped molecules can be precursors for intrachromosomal amplicons. The formation of HSRs can be accounted for either by breakage-fusion-bridge (BFB) cycle which necessitates nonhomologous end-joining pathway (NHEJ) or by the repair event involving homologous recombination (HR). In this study, we report that intrachromosomal gene amplification mediated by hairpin-capped DSBs is independent of NHEJ machinery, however requires the functions of Rad52 and Rad51 proteins. Based on our observations, we propose a HR-dependent mechanism to explain how the breakage of dicentric chromosomes can lead to the formation of HSRs.

Hairpin- and cruciform-mediated chromosome breakage: causes and consequences in eukaryotic cells.

Chromosomes of many eukaryotic organisms including humans contain a large number of repetitive sequences. Several types of commonly present DNA repeats have the capacity to adopt hairpin and cruciform secondary structures. Inverted repeats, AT- and GC-rich micro- and minisatellites, comprising this class of sequence motifs, are frequently found in chromosomal regions that are prone for gross rearrangements in somatic and germ cells. Recent studies in yeast and mammals indicate that a double-strand break occurring at the sites of unstable repeats can be an initial event in the generation of chromosome rearrangements. The repeat-induced chromosomal instability is responsible for a number of human diseases and has been implicated in carcinogenesis. In this review, we discuss the molecular mechanisms by which hairpins and cruciforms can trigger chromosomal fragility and subsequent aberrations in eukaryotic cells. We also address the relationship between secondary structure-mediated genetic instability and human pathology.

Inverted DNA repeats channel repair of distant double-strand breaks into chromatid fusions and chromosomal rearrangements.

Inverted DNA repeats are known to cause genomic instabilities. Here we demonstrate that double-strand DNA breaks (DSBs) introduced a large distance from inverted repeats in the yeast (Saccharomyces cerevisiae) chromosome lead to a burst of genomic instability. Inverted repeats located as far as 21 kb from each other caused chromosome rearrangements in response to a single DSB. We demonstrate that the DSB initiates a pairing interaction between inverted repeats, resulting in the formation of large dicentric inverted dimers. Furthermore, we observed that propagation of cells containing inverted dimers led to gross chromosomal rearrangements, including translocations, truncations, and amplifications. Finally, our data suggest that break-induced replication is responsible for the formation of translocations resulting from anaphase breakage of inverted dimers. We propose a model explaining the formation of inverted dicentric dimers by intermolecular single-strand annealing (SSA) between inverted DNA repeats. According to this model, anaphase breakage of inverted dicentric dimers leads to gross chromosomal rearrangements (GCR). This "SSA-GCR" pathway is likely to be important in the repair of isochromatid breaks resulting from collapsed replication forks, certain types of radiation, or telomere aberrations that mimic isochromatid breaks.