Genes required for phosphosphingolipid formation in Caulobacter crescentus contribute to bacterial virulence.

Sphingolipids are ubiquitous in membranes of eukaryotes and are associated with important cellular functions. Although sphingolipids occur scarcely in bacteria, for some of them they are essential and, in other bacteria, they contribute to fitness and stability of the outer membrane, such as in the well-studied α-proteobacterium Caulobacter crescentus. We previously defined five structural genes for ceramide synthesis in C. crescentus, among them the gene for serine palmitoyltransferase, the enzyme that catalyzes the committed step of sphingolipid biosynthesis. Other mutants affected in genes of this same genomic region show cofitness with a mutant deficient in serine palmitoyltransferase. Here we show that at least two phosphosphingolipids are produced in C. crescentus and that at least another six gene products are needed for the decoration of ceramide upon phosphosphingolipid formation. All eleven genes participating in phosphosphingolipid formation are also required in C. crescentus for membrane stability and for displaying sensitivity towards the antibiotic polymyxin B. The genes for the formation of complex phosphosphingolipids are also required for C. crescentus virulence on Galleria mellonella insect larvae.

Multiple approaches of cellular metabolism define the bacterial ancestry of mitochondria.

We breathe at the molecular level when mitochondria in our cells consume oxygen to extract energy from nutrients. Mitochondria are characteristic cellular organelles that derive from aerobic bacteria and carry out oxidative phosphorylation and other key metabolic pathways in eukaryotic cells. The precise bacterial origin of mitochondria and, consequently, the ancestry of the aerobic metabolism of our cells remain controversial despite the vast genomic information that is now available. Here, we use multiple approaches to define the most likely living relatives of the ancestral bacteria from which mitochondria originated. These bacteria live in marine environments and exhibit the highest frequency of aerobic traits and genes for the metabolism of fundamental lipids that are present in the membranes of eukaryotes, sphingolipids, and cardiolipin.

Traumatic Brain Injury: Intraoperative Management and Intensive Care Unit Multimodality Monitoring.

Traumatic brain injury is a devastating event associated with substantial morbidity. Pathophysiology involves the initial trauma, subsequent inflammatory response, and secondary insults, which worsen brain injury severity. Management entails cardiopulmonary stabilization and diagnostic imaging with targeted interventions, such as decompressive hemicraniectomy, intracranial monitors or drains, and pharmacological agents to reduce intracranial pressure. Anesthesia and intensive care requires control of multiple physiologic variables and evidence-based practices to reduce secondary brain injury. Advances in biomedical engineering have enhanced assessments of cerebral oxygenation, pressure, metabolism, blood flow, and autoregulation. Many centers employ multimodality neuromonitoring for targeted therapies with the hope to improve recovery.

Specialized acyl carrier protein used by serine palmitoyltransferase to synthesize sphingolipids in Rhodobacteria.

Serine palmitoyltransferase (SPT) catalyzes the first and committed step in sphingolipid biosynthesis condensating L-serine and acyl-CoA to form 3-oxo-sphinganine. Whenever the structural gene for SPT is present in genomes of Rhodobacteria (α-, ß-, and γ-Proteobacteria), it co-occurs with genes coding for a putative acyl carrier protein (ACP) and a putative acyl-CoA synthetase (ACS). In the α-proteobacterium Caulobacter crescentus, CC_1162 encodes an SPT, whereas CC_1163 and CC_1165 encode the putative ACP and ACS, respectively, and all three genes are known to be required for the formation of the sphingolipid intermediate 3-oxo-sphinganine. Here we show that the putative ACP possesses a 4'-phosphopantetheine prosthetic group, is selectively acylated by the putative ACS and therefore is a specialized ACP (AcpR) required for sphingolipid biosynthesis in Rhodobacteria. The putative ACS is unable to acylate coenzyme A or housekeeping ACPs, but acylates specifically AcpR. Therefore, it is a specialized acyl-ACP synthetase (AasR). SPTs from C. crescentus, Escherichia coli B, or Sphingomonas wittichii use preferentially acyl-AcpR as thioester substrate for 3-oxo-sphinganine synthesis. Whereas acyl-AcpR from C. crescentus is a good substrate for SPTs from distinct Rhodobacteria, acylation of a specific AcpR is achieved by the cognate AasR from the same bacterium. Rhodobacteria might use this more complex way of 3-oxo-sphinganine formation in order to direct free fatty acids toward sphingolipid biosynthesis.

Computer Visual Syndrome in Medical Students From a Private University in Paraguay: A Survey Study.

Purpose: To determine the prevalence and factors associated with computer vision syndrome in medical students at a private university in Paraguay. Methods: A survey study was conducted in 2021 in a sample of 228 medical students from the Universidad del Pacífico, Paraguay. The dependent variable was CVS, measured with the Computer Visual Syndrome Questionnaire (CVS-Q). Its association with covariates (hours of daily use of notebook, smartphone, tablet and PC, taking breaks when using equipment, use of preventive visual measures, use of glasses, etc.) was examined. Results: The mean age was 22.3 years and 71.5% were women. CVS was present in 82.5% of participants. Higher prevalence of CVS was associated with wearing a framed lens (PR = 1.11, 95% CI: 1.03-1.20). In contrast, taking a break when using electronic equipment at least every 20 min and every 1 h reduced 7% (PR = 0.93, 95% CI: 0.87-0.99) and 6% (PR = 0.94, 95% CI: 0.89-0.99) the prevalence of CVS, respectively. Conclusion: Eight out of 10 students experienced CVS during the COVID-19 pandemic. The use of framed lenses increased the presence of CVS, while taking breaks when using electronic equipment at least every 20 min and every 1 h reduced CVS.

Five structural genes required for ceramide synthesis in Caulobacter and for bacterial survival.

Sphingolipids are essential and common membrane components in eukaryotic organisms, participating in many important cellular functions. Only a few bacteria are thought to harbour sphingolipids in their membranes, among them the well-studied α-proteobacterium Caulobacter crescentus, a model organism for asymmetric cell division and cellular differentiation. Here, we report that C. crescentus wild type produces several molecular species of dihydroceramides, which are not produced in a mutant lacking the structural gene for serine palmitoyltransferase (spt). Whereas growth of a spt-deficient mutant and wild type are indistinguishable during the exponential phase of growth, survival of the spt-deficient mutant is much reduced, in comparison with wild type, during stationary phase of growth, especially at elevated temperatures. The structural gene for spt is located within a genomic cluster, comprising another 16 genes and which, like spt, are important for fitness of C. crescentus. Mutants deficient in genes linked to spt by high cofitness were unable to produce dihydroceramide or to survive in stationary phase of growth at elevated temperatures. At least five structural genes are required for dihydroceramide biosynthesis in C. crescentus and sphingolipid biosynthesis is needed for survival of this bacterium and the integrity of its outer membrane.

The Clinical Contribution of Neurovascular Ultrasonography in Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Patients with acute ischemic stroke receive computed tomography angiogram (CTA) and digital subtraction angiogram (DSA) for clinical evaluation. Current guidelines lack in defining indications for transcranial Doppler (TCD) and/or carotid duplex ultrasonography (CUS) in acute stroke evaluation or follow-up cerebrovascular imaging after reperfusion. We investigated the clinical utility of performing additional TCD/CUS after reperfusion in guiding postacute care stroke management. METHODS: Retrospective review of acute ischemic stroke patients admitted to a comprehensive stroke center with CTA head and neck and/or DSA followed by TCD/CUS. Cases were reviewed by two authors to determine if TCD/CUS provided additional diagnostic information to aid management. A nominal group process, using a third author, achieved consensus in cases of disagreements. RESULTS: Only 25 of 198 patients had CTA or DSA followed by TCD/CUS. Ten (40%) cases showed new clinical information from CUS aiding management. Of those with TCD, 5 patients (22.7%) had findings that impacted management. These clinical scenarios included detection of mobile thrombus requiring anticoagulation; distinguishing carotid near-occlusion from occlusion; confirming hemodynamic significance of intra/extracranial stenosis helping emergent stenting/endarterectomy; detecting hyperperfusion on TCDs causing symptoms; and establishing chronicity of carotid stenosis based on collateral flow patterns, which deferred further intervention. DISCUSSION: Our experience shows that TCD/CUS may offer additional diagnostic information assisting postacute care management in small subset of patients with acute ischemic stroke. Larger studies are needed to research the clinical impact and cost-effectiveness of additional imaging and inform clinical guidelines for selecting patients who will benefit from these additional studies.

Management of Self-Injurious Behavior, Aggression, and Psychogenic Non-Epileptic Seizures in Patients With Tuberous Sclerosis: A Case Report With a Review of Literature.

Tuberous sclerosis complex (TSC) is a neurocutaneous disorder that affects multiple systems. TSC encompasses neurobehavioral abnormalities that are considered less sensitive and specific to the disease. Autism spectrum disorder, attention deficit disorder, anxiety, mood disorders, and self-injurious behavior (SIB) are neurobehavioral manifestations associated with tuberous sclerosis. Among them, SIB is poorly described and studied. We present a case report and a brief review of the literature, which offers us insight into the pathological mechanism that explains associated SIB in TSC patients and provides a possible multidisciplinary approach to handle this complicated association. The case details a 21-year-old female with tuberous sclerosis who went to the emergency department and then transfer to the psychiatric floor due to aggressive behavior and SIB. The patient had a history of infantile spasm in childhood and generalized tonic-clonic seizures (GTCS); the last episode was four years ago at the age of 17. During the hospital admission, the patient developed an apparent tonic-clonic seizure. Nevertheless, the electroencephalogram (EEG) shows no epileptiform pattern and because of the clinical presentation, it was concluded she had psychogenic nonepileptic seizures (PNES). The patient's CT scan showed a stable appearance of multiple calcified subependymal nodules and left frontal hypodensity. Mini-mental examination (MMSE) revealed mild cognitive impairment. Patients with TSC/SIB have higher frequencies of mental retardation, TSC2 mutations, history of infantile spasms, spike focus in the left frontal lobe. Also, TSC/SIB patients have a higher frequency of tubers in quadrants other than the left posterior neuroanatomical region in left occipital, parietal, and posterior temporal lobes. Our patient had four out of five of the risks factor for developing TSC/SIB. Almost all patients with tuberous sclerosis are expected to develop seizures. Nevertheless, our patient was seizure-free for two years and managed prophylactically with antiepileptic medication. PNES can also occur in patients with tuberous sclerosis. It is essential to be attentive to differentiate PNES from actual seizures due to their history of the high frequency of seizures in TSC. Given the multiple systems involved in the symptomatology of TSC, including the SIB and neurological concerns, multidisciplinary treatment strategies must be implemented. Treatment of TSC with SIB should include antiepileptic drugs covering seizures and managing the SIB's mood component. A neuroleptic could be added for patients who are difficult to manage.

Development of a Homemade Spinal Model for Simulation to Teach Ultrasound Guidance for Lumbar Puncture.

BACKGROUND: Spinal procedures such as lumbar punctures (LPs), epidurals, and spinal blocks are essential components to clinical practice but are challenging to teach, learn, or practice on real patients due to patient safety and comfort limiting the number of attempts. Resident physicians traditionally learn these spinal procedural skills through observation of a more senior physician before attempting the procedure. Simulation using models can improve providers' competency without introducing an added risk to patients. A difficulty encountered with access to simulation training for such procedures is the limited availability of simulators. While there are several high-quality, commercially available models that mimic the anatomy of lumbar spine, the cost of these models often limits the access to students and practitioners. The other challenge is access to simulators with versatility that can be used for palpation as well as ultrasound (US)-guided procedures. A simulator that can combine practice of both palpation and US-guided modalities would be efficacious in reducing cost to the teaching institutions. We attempted to overcome the access barrier to spinal models by developing an alternative that provides a good simulator for both palpation and US-guided LP while keeping the cost low. Our model can be easily manufactured by not only clinicians but also medical students. METHODS: A literature review was conducted to assess the available research and information on the production and use of simulators for practicing LPs and other spinal procedures. Publications queried described the production of models and utilizing the information compiled we devised and fabricated a model. RESULTS: A lumbar spine model was developed using computed tomography spine data of an average-sized male patient without lumbar spine pathology. The model was created using medical imaging processing software and printed on 3D printer using nylon plastic. This model was then utilized by residents, advanced practice providers, and medical students for palpation and US-guided LP simulation training. CONCLUSIONS: An inexpensive reusable non-commercial LP simulator can be an effective method for teaching invasive procedures like LPs, especially if it can be used both for palpation and US-guided procedures. The method outlined here can be easily reproduced in a relatively short amount of time. We recognize one limitation in the widespread dissemination of this technique being access to a 3D printer and digital designs for printing. Future studies will be necessary to determine the efficacy of the homemade LP simulator in teaching neurointensivist in training.