The discovery that the dilute gene encodes a class V myosin led to the hypothesis that this molecular motor is involved in melanosome transport and/or dendrite outgrowth in mammalian melanocytes. The present studies were undertaken to gain insight into the subcellular distribution of myosin-V in the melanoma cell line B16-F10, which is wildtype for the dilute gene. Immunofluorescence studies showed some degree of superimposed labeling of myosin-V with melanosomes that predominated at the cell periphery. A subcellular fraction highly enriched in melanosomes was also enriched in myosin-V based on Western blot analysis. Immunoelectron microscopy showed myosin-V labeling associated with melanosomes and other organelles. The stimulation of B16 cells with the ␣-melanocyte-stimulating hormone led to a significant increase in myosin-V expression. This is the first evidence that a cAMP signaling pathway might regulate the dilute gene expression. Immunofluorescence also showed an intense labeling of myosin-V independent of melanosomes that was observed within the dendrites and at the perinuclear region. Although the results presented herein are consistent with the hypothesis that myosin-V might act as a motor for melanosome translocation, they also suggest a broader cytoplasmic function for myosin-V, acting on other types of organelles or in cytoskeletal dynamics.

Background : SARS-CoV-2 quickly spreads in the worldwide population, imposing social restrictions to control the infection, being the massive testing another essential strategy to break the chain of transmission. Aim : To compare the performance of at-home self-collected samples – saliva and combined nasal-oropharyngeal swabs (NOP) – for SARS-CoV-2 detection in a telemedicine platform for COVID-19 surveillance. Material and methods : We analyzed 201 patients who met the criteria of suspected COVID-19. NOP sampling was combined (nostrils and oropharynx) and saliva collected using a cotton pad device. Detection of SARS-COV-2 was performed by using the Altona RealStar® SARS-CoV-2 RT-PCR Kit 1.0. Results: There was an overall significant agreement (κ coefficient value of 0.58) between saliva and NOP. Considering results in either sample, 70 patients positive for SARS-CoV-2 were identified, with 52/70 being positive in NOP and 55/70 in saliva. This corresponds to sensitivities of 74.2% (95% CI; 63.7% to 83.1%) for NOP and 78.6% (95% CI; 67.6% to 86.6%) for saliva. Conclusion : Our data show the feasibility of using at-home self-collected samples (especially saliva), as an adequate alternative for SARS-CoV-2 detection. This new approach of testing can be useful to develop strategies for COVID-19 surveillance and for guiding public health decisions.

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Griscelli syndrome (GS) is caused by mutations in the MYO5A (GS1), RAB27A (GS2), or MLPH (GS3) genes, all of which lead to a similar pigmentary dilution. In addition, GS1 patients show primary neurological impairment, whereas GS2 patients present immunodeficiency and periods of lymphocyte proliferation and activation, leading to their infiltration in many organs, such as the nervous system, causing secondary neurological damage. We report the diagnosis of GS2 in a 4-year-old child with haemophagocytic syndrome, immunodeficiency, and secondary neurological disorders. Typical melanosome accumulation was found in skin melanocytes and pigment clumps were observed in hair shafts. Two heterozygous mutant alleles of the RAB27A gene were found, a C-T transition (C352T) that leads to Q118stop and a G-C transversion on the exon 5 splicing donor site (G467+1C). Functional assays showed increased cellular activation and decreased cytotoxic activity of NK and CD8+ T cells, associated with defective lytic granules release. Myosin-Va expression and localization in the patient lymphocytes were also analyzed. Most importantly, we show that cytotoxic activity of the patient's CD8+ T lymphocytes can be rescued in vitro by RAB27A gene transfer mediated by a recombinant retroviral vector, a first step towards a potential treatment of the acute phase of GS2 by RAB27A transduced lymphocytes.

BackgroundDespite most cases not requiring hospital care, there are limited community-based clinical data on COVID-19.MethodsThe Corona São Caetano programme is a primary care initiative providing care to all residents with COVID-19 in São Caetano do Sul, Brazil. It was designed to capture standardised clinical data on community COVID-19 cases. After triage of potentially severe cases, consecutive patients presenting to a multimedia screening platform between 13 April and 13 May 2020 were tested at home with SARS-CoV-2 reverse transcriptase (RT) PCR; positive patients were followed up for 14 days with phone calls every 2 days. RT-PCR-negative patients were offered additional SARS-CoV-2 serology testing to establish their infection status. We describe the clinical, virological and natural history features of this prospective population-based cohort.FindingsOf 2073 suspected COVID-19 cases, 1583 (76.4%) were tested by RT-PCR, of whom 444 (28.0%, 95% CI 25.9 to 30.3) were positive; 604/1136 (53%) RT-PCR-negative patients underwent serology, of whom 52 (8.6%) tested SARS-CoV-2 seropositive. The most common symptoms of confirmed COVID-19 were cough, fatigue, myalgia and headache; whereas self-reported fever (OR 3.0, 95% CI 2.4 to 3.9), anosmia (OR 3.3, 95% CI 2.6 to 4.4) and ageusia (OR 2.9, 95% CI 2.3 to 3.8) were most strongly associated with a positive COVID-19 diagnosis by RT-PCR or serology. RT-PCR cycle thresholds were lower in men, older patients, those with fever and arthralgia and closer to symptom onset. The rates of hospitalisation and death among 444 RT-PCR-positive cases were 6.7% and 0.7%, respectively, with older age and obesity more frequent in the hospitalised group.ConclusionCOVID-19 presents in a similar way to other mild community-acquired respiratory diseases, but the presence of fever, anosmia and ageusia can assist the specific diagnosis. Most patients recovered without requiring hospitalisation with a low fatality rate compared with other hospital-based studies.

Muscle degenerative diseases such as Duchenne Muscular Dystrophy are incurable and treatment options are still restrained. Understanding the mechanisms and factors responsible for muscle degeneration and regeneration will facilitate the development of novel therapeutics. Several recent studies have demonstrated that Galectin-1 (Gal-1), a carbohydrate-binding protein, induces myoblast differentiation and fusion in vitro, suggesting a potential role for this mammalian lectin in muscle regenerative processes in vivo. However, the expression and localization of Gal-1 in vivo during muscle injury and repair are unclear. We report the expression and localization of Gal-1 during degenerative-regenerative processes in vivo using two models of muscular dystrophy and muscle injury. Gal-1 expression increased significantly during muscle degeneration in the murine mdx and in the canine Golden Retriever Muscular Dystrophy animal models. Compulsory exercise of mdx mouse, which intensifies degeneration, also resulted in sustained Gal-1 levels. Furthermore, muscle injury of wild-type C57BL/6 mice, induced by BaCl(2) treatment, also resulted in a marked increase in Gal-1 levels. Increased Gal-1 levels appeared to localize both inside and outside the muscle fibers with significant extracellular Gal-1 colocalized with infiltrating CD45(+) leukocytes. By contrast, regenerating muscle tissue showed a marked decrease in Gal-1 to baseline levels. These results demonstrate significant regulation of Gal-1 expression in vivo and suggest a potential role for Gal-1 in muscle homeostasis and repair.

Duchenne muscular dystrophy (DMD) is characterized by the absence of dystrophin. Several previous studies demonstrated the feasibility of delivering microdystrophin complementary DNA (cDNA) into mouse and normal nonhuman primate muscles by ex vivo gene therapy. However, these animal models do not reproduce completely the human DMD phenotype, while the dystrophic dog model does. To progress toward the use of the best animal model of DMD, a dog microdystrophin was transduced into human and dystrophic dog muscle precursor cells (MPCs) with a lentivirus before their transplantation into mouse muscles. One month following MPC transplantation, myofibers expressing the dog microdystrophin were observed. We also used another approach to introduce this transgene into myofibers, i.e., the electrotransfer of a plasmid coding for the dog microdystrophin. The plasmid was injected into mouse and dog muscles, and brief electric pulses were applied in the region of injection. Two weeks later, the transgene was detected in both animals. Therefore, ex vivo gene therapy and electrotransfer are two possible methods to introduce a truncated version of dystrophin into myofibers of animal models and eventually into myofibers of DMD patients.

Background: Despite most cases not requiring hospital care, there are limited community-based clinical data on COVID-19. Methods and findings: The Corona Sao Caetano program is a primary care initiative offering COVID-19 care to all residents of Sao Caetano do Sul, Brazil. After triage of potentially severe cases, consecutive patients presenting between 13th April and 13th May 2020 were tested at home with SARS-CoV-2 reverse transcriptase (RT) PCR; positive patients were followed up for 14 days. RT-PCR-negative patients were offered SARS-CoV-2 serology. We describe the clinical features, virology and natural history of this prospective population-based cohort. Of 2,073 suspected COVID-19 cases, 1,583 (76.4%) were tested by RT-PCR, of whom 444 (28.0%, 95%CI: 25.9% - 30.3%) were positive; 604/1,136 (53%) RT-PCR-negative patients underwent serology, of whom 52 (8.6%) tested SARS-CoV-2 seropositive. The most common symptoms of COVID-19 were cough, fatigue, myalgia and headache; whereas self-reported fever, anosmia, and ageusia were most associated with a positive COVID-19 diagnosis. RT-PCR cycle thresholds were lower in men, older patients, those with fever and arthralgia, and around symptom onset. The rates of hospitalization and death among 444 RT-PCR-positive cases were 6.7% and 0.7%, respectively, with older age and obesity more frequent in the hospitalized group. Conclusions: COVID-19 presents similarly to other mild respiratory disease in primary care. Some symptoms assist the differential diagnosis. Most patients can be managed at home.