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Coronavirus disease-19 (COVID-19), a pandemic caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), is a primarily respiratory tract disease. Suitable animal models for COVID-19 are required to study various aspects of pathogenesis, drug discovery, effective and safe vaccine development. Several laboratory animals including, non-human primates, hamsters, ferrets, transgenic mice, and zebrafish, have been used and proven their significance experimentally. Currently available animal models of SARS-CoV-2 can be broadly classified into two categories 1) natural animal models 2) genetically-modified that exhibit different degrees of susceptibility of SARS-CoV-2, tissue damage in respiratory and other organ systems. Not all the available animal models mimic COVID-19-like phenotype completely. Therefore, understanding various aspects of COVID-19 requires different animal models. In this review article, we provide an update on the immune response and clinical manifestations observed in naturally occurring and genetically-modified animals of COVID-19. We then review the transmission, viral replication, lung pathology, immunological aspects, and extrapulmonary phenotypes observed in various animal models. In the end, we put forth our perspective on the anticipated uses, disadvantages, and limitations of each type of animal model. SARS-CoV-2 infected individuals can experience a range of clinical features ranging from no symptoms to critical illness associated with respiratory failure, septic shock, and multi-organ failure. Additionally, SARS-CoV-2 infection is not restricted to the respiratory tract due to the multi-organ expression of ACE2. Further, the emergence of SARS-CoV-2 variants-of-concern demands continuous research on host transmission, evasion from host immune response, and development of effective and durable vaccines. A better understanding of the pathogenesis, severity, incubation period, scorable symptoms, effective treatment modalities with the least side effects, and boosting of the immune system can reduce the disease obstacles for the society as well as an individual person. Therefore, to investigate various aspects of SARS-CoV-2 infection and COVID-19 requires suitable animal models. Several laboratory animals including, non-human primates (NHPs), hamsters, ferrets, transgenic mice, zebrafish, guinea pigs, minks, have been considered and proven their significance experimentally. Currently available animal models of COVID-19, either natural host or genetically modified, exhibit different degrees of susceptibility of SARS-CoV-2 tissue damage in respiratory and other organ systems. Not all the available animal models mimic the COVID-19 like phenotype completely. Therefore, understanding different aspects of COVID-19 will require different animal models. In the proposed article, we have reviewed the immunological and clinical manifestations observed in various natural, and genetically-modified animal models of numerous COVID-19 studies. We also summarized the up-to-date laboratory findings on available on significant COVID-19 animal models, and put forth our perspective for the objective dependent usage of animal models. [ABSTRACT FROM AUTHOR]

Significance: The photoacoustic (PA) technique, a noninvasive pump-probe technique, has found interesting applications in biomedical tissue diagnosis over the last decade. To take it a step further to clinical applications, the PA technique needs to be designed as an instrument focusing on a compact design, reducing the cost, and quickly providing a quantitative diagnosis. Aim: This work presents a design and characterization of a cost-effective, compact PA sensing instrument for biomedical tissue diagnosis. Approach: A compact laser diode case design is developed to house several laser diodes for PA excitation, and a pulsed current supply unit is also developed in-house to power the laser diodes to generate a 25 ns current pulse at a frequency of 20 kHz. After PA experimental data acquisition, the signal's frequency spectra were calculated to characterize the tissue quantitatively and correlated with their mechanobiological properties. Results: The corresponding dominant frequency peak in the PA spectral response (PASR) study was low in the fibrofatty normal breast tissue 0.26 x 0.03 MHz, compared to the dominant frequency peak of 1.60 x 0.016 MHz in the fibrocystic disease tissue, which had increased glandular and stromal elements, thereby increased tissue density. The histopathological findings correlated with the PASR results, and the fibrocystic breast disease tissue exhibited a higher dominant frequency peak and energy compared to the normal breast tissue. Conclusions: We experimented with an in vitro PASR study of fibrocystic human breast tissues and successfully differentiated different tissue types using quantitative spectral parameters peak frequency, mean frequency, and spectral energy. This gives the potential to take this technique further for cost-effective and quick clinical applications. [ABSTRACT FROM AUTHOR]

This paper introduces GREEDS as a new measure of optimistic sentiment in the market. We measure the optimistic component of investor sentiment by constructing the Geographically Revealed Economic Expectations disclosed by Search (GREEDS) index from households' search behavior on Google for a sample of 38 countries. Our results reveal that the GREEDS index positively correlates with global stock returns. We show the asymmetric effect of GREEDS, which is more prevalent in developed countries than emerging markets. Our findings also highlight the role of global sentiment in financial markets through the sentiment commonality effect. [ABSTRACT FROM AUTHOR]

Background: Bronchoalveolar lavage (BAL) is a widely accepted investigative tool for the diagnosis of pulmonary lesions. This study was done to find out the usefulness of BAL in diagnosis of pulmonary lesions from central Indian patient population. Methods: A cross-sectional prospective study was performed over a period of three years. All the BAL specimens of patients presenting to Department of Pulmonary Medicine and Tuberculosis during a period of January 2017 to December 2019 were included in the study. Cyto-histopathologic correlation was done, wherever available. Results: Of total 277 cases, there were 178 (64.5%) males and 99 (35.5%) females. The age of patients ranged from 4 years to 82 years. In 92 (33%) cases, specific infective etiology could be identified on BAL cytology, the most common being tuberculosis (26%) followed by fungal infections (2%). Rarely, infections like nocardia, actinomycosis, and hydatidosis were also identified. Eight cases (3%) of malignancy were identified which included two cases of adenocarcinoma, one case of small cell carcinoma, three cases of poorly differentiated carcinoma, and two cases suspicious for malignancy. Some rare diagnoses like diffuse alveolar damage, pulmonary alveolar microlithiasis, and pulmonary alveolar proteinosis could be identified on BAL. Conclusion: BAL is useful in primary diagnosis of infections and malignancies of lower respiratory tract. BAL may aid in diagnostic workup of diffuse lung diseases. A combination of clinical information, high-resolution computed tomography, and BAL analysis may furnish an assured diagnosis to the clinician and obviate need for invasive procedures. [ABSTRACT FROM AUTHOR]