Human Brain Organoids as Models for Central Nervous System Viral Infection

Pathogenesis of viral infections of the central nervous system (CNS) is poorly understood, and this is partly due to the limitations of currently used preclinical models. Brain organoid models can overcome some of these limitations, as they are generated from human derived stem cells, differentiated in three dimensions (3D), and can mimic human neurodevelopmental characteristics. Therefore, brain organoids have been increasingly used as brain models in research on various viruses, such as Zika virus, severe acute respiratory syndrome coronavirus 2, human cytomegalovirus, and herpes simplex virus. Brain organoids allow for the study of viral tropism, the effect of infection on organoid function, size, and cytoarchitecture, as well as innate immune response; therefore, they provide valuable insight into the pathogenesis of neurotropic viral infections and testing of antivirals in a physiological model. In this review, we summarize the results of studies on viral CNS infection in brain organoids, and we demonstrate the broad application and benefits of using a human 3D model in virology research. At the same time, we describe the limitations of the studies in brain organoids, such as the heterogeneity in organoid generation protocols and age at infection, which result in differences in results between studies, as well as the lack of microglia and a blood brain barrier.     

Computer-aided analysis of gait rhythm fluctuations in amyotrophic lateral sclerosis

Deterioration of motor neurons due to amyotrophic lateral sclerosis (ALS) would affect the strides from one gait cycle to the next. Computer-assisted techniques are useful for gait analysis, and also have high potential in quantitatively monitoring the pathological progression. In this paper, we applied the signal turns count method to measure the fluctuations in the swing-interval time series recorded from 16 healthy control subjects and 13 patients with ALS. The swing-interval turns count (SWITC) parameter derived with the threshold of 0.06 s presented a significant difference (p < 0.001) between the healthy control subjects and ALS patients. Besides the SWITC, we also computed the averaged stride interval (ASI), which is usually longer in the patient with ALS (p < 0.0001), to characterize the gait patterns of ALS patients. In the pattern classification experiments, the Fisher’s linear discriminant analysis (FLDA) and the least squares support vector machine (LS-SVM), both input with the SWITC and ASI features, were evaluated using the leave-one-out cross-validation method. The results showed that the LS-SVM with sigmoid kernels was able to provide a classification accurate rate of 89.66% and an area of 0.9629 under the receiver operating characteristic (ROC) curve, which were superior to those obtained with the linear classifier in the form of FLDA.     

Comparative analysis of the large fragment of the 5′ untranslated region (LF-5′ UTR) of serotype A foot-and-mouth disease virus field isolates from India

India is endemic for foot-and-mouth disease (FMD) and in recent years a unique group within serotype A, carrying a codon deletion at an antigenically critical site in capsid protein VP3 has emerged (VP3⁵⁹-deletion group). This tempted us to analyze the noncoding region, which is an under represented area, though critically associated with virus biology and pathogenesis. Analysis of the large fragment of 5′ untranslated region (LF-5′ UTR) of type A FMD virus revealed discrepancy in the overall tree topology between LF-5′ UTR and 1D region possibly due to independent evolution of coding and noncoding regions. The VP3⁵⁹-deletion group maintained its phylogenetic distinctness even at the LF-5′ UTR. Eighteen lineage specific signatures detected here support independent evolutionary paths for the lineages. Extensive deletions of 45 and 89 nucleotides corresponding to the pseudoknot region were noticed. Conservation pattern in the ‘A₂₅₃AACA’ motif in the cre/bus stem-loop indicates the importance of first three ‘A’ residues in VPg uridylylation. Of the three polypyrimidine tract binding protein (PTB) binding sites mapped on the internal ribosome entry site (IRES), the pyrimidine tract (Py tract) in the loop of domain 2 was found to be maximally conserved and it might be the major PTB binding site. Strikingly, a deletion group lineage specific transversion was noticed in the Py tract at the 3′ end of IRES without significantly affecting its in vitro infectious titer. Hence, we presume that for efficient cap-independent viral translation, either a minimum number of pyrimidine residues rather than a complete Py tract or a Py tract tolerating transversions only at specific locations and a core motif ‘CUUU’ within the Py tract is essential.     

“Hands‐Free” Continuous Echocardiography during Treadmill Exercise Using a Novel Ultrasound Transducer

Background: Echocardiographic imaging using a handheld transducer in conjunction with treadmill exercise testing is commonly used for the diagnosis of coronary artery disease. Motion of the hand and the transducer during peak exercise preclude optimal imaging. To circumvent the limitations of handheld transducers, we developed a low profile transducer (CONTISON) which can be attached to the chest wall for continuous cardiac imaging. Methods and Results: This feasibility study was performed in 10 normal male subjects (28 to 36 years). The ultrasound transducer was placed in the third or fourth intercostal space at the left sternal border to permit imaging of the left ventricle in its short axis. The transducer was interfaced with a commercially available ultrasound machine. The left ventricle was imaged at rest and while subjects exercised according to a standard Bruce protocol. All segments of the left ventricular short axis were seen at rest and peak exercise. Increased left ventricular wall thickening and wall motion were seen at peak exercise. There were no complications from the procedure. Conclusion: We demonstrated the feasibility of hands‐free left ventricular imaging during treadmill exercise using the CONTISON transducer. Further evaluation of the technique to detect stress‐induced wall motion abnormalities, as a means of diagnosing myocardial ischemia, appears warranted. (ECHOCARDIOGRAPHY 2010;27:563‐566)     

Primary mucormycosis of abdominal wall: A rare fungal infection in a immunocompetent patient

Mucormycosis of the anterior abdominal wall is an uncommon disease and it is very rare to find this disease in immunocompetent, non-diabetic patients which usually affects patients with trauma, with contaminated wounds, patients with underlying malignancies or patients with immunocompromised state, e.g., diabetics. We herein report a case of primary cutaneous mucormycosis in an immunocompetent and non-diabetic patient. Our patient was a 48-year-old female, executive by profession. She was diagnosed to have cutaneous mucormycosis of the anterior abdominal wall, and was managed with multiple debridements of the wound and intravenous amphotericin B therapy. She was administered a total of 1500 mg of liposomal amphotericin B and when fully healed, split skin grafting was done. We would like to emphasize the importance of high index of suspicion and early start of therapy in a condition with high rate of mortality.     

Amniotic membrane transplantation in the management of shield ulcers of vernal keratoconjunctivitis.

PURPOSE: To report our experience with amniotic membrane transplantation in the management of severe shield ulcers. DESIGN: Retrospective, interventional, noncomparative case series. PARTICIPANTS: Four patients (seven eyes) with grade 2 (ulcer with opaque base) and grade 3 (plaquelike lesions) shield ulcers not responding to steroid therapy with or without surgical debridement. INTERVENTION: Amniotic membrane transplantation with stromal side down was performed after meticulous debridement of the ulcer. MAIN OUTCOME MEASURES: Healing of the ulcer with no epithelial defect. RESULTS: The ulcers healed with disintegration or retraction of the membrane in all patients within 2 weeks. CONCLUSIONS: Amniotic membrane transplantation in combination with debridement is an effective surgical modality in the management of severe shield ulcers. Further studies are warranted to confirm the efficacy of amniotic membrane transplantation in the management of shield ulcer and its correct position in the treatment algorithm.