Somatosensory Psychophysical Losses in Inhabitants of Riverside Communities of the Tapajós River Basin,Amazon, Brazil: Exposure to Methylmercury Is Possibly Involved

The purpose of this work was to evaluate the somatosensory system of methylmercury-exposed inhabitants living in the communities of the Tapajós river basin by using psychophysical tests and to compare with measurements performed in inhabitants of the Tocantins river basin. We studied 108 subjects from Barreiras and São Luiz do Tapajós, two communities of the Tapajós river basin, State of Pará, Amazon, Brazil, aged 13–53 years old. Mercury analysis was performed in head hair samples weighting 0.1–0.2 g by using atomic absorption spectrometry. Three somatosensory psychophysical tests were performed: tactile sensation threshold, vibration sensation duration, and two-point discrimination. Semmes-Weinstein 20 monofilaments with different diameters were used to test the tactile sensation in the lower lip, right and left breasts, right and left index fingers, and right and left hallux. The threshold was the thinner monofilament perceived by the subject. Vibration sensation was investigated using a 128 Hz diapason applied to the sternum, right and left radial sides of the wrist, and right and left outer malleoli. Two trials were performed at each place. A stopwatch recorded the vibration sensation duration. The two-point discrimination test was performed using a two-point discriminator. Head hair mercury concentration was significantly higher in mercury-exposed inhabitants of Tapajós than in non-exposed inhabitants of Tocantins (p < 0.01). When all subjects were divided in two groups independently of age—mercury-exposed and non-exposed—the following results were found: tactile sensation thresholds in mercury-exposed subjects were higher than in non-exposed subjects at all body parts, except at the left chest; vibration sensation durations were shorter in mercury-exposed than in non-exposed subjects, at all locations except in the upper sternum; two-point discrimination thresholds were higher in mercury-exposed than in non-exposed subjects at all body parts. There was a weak linear correlation between tactile sensation threshold and mercury concentration in the head hair samples. No correlation was found for the other two measurements. Mercury-exposed subjects had impaired somatosensory function compared with non-exposed control subjects. Long-term mercury exposure of riverside communities in the Tapajós river basin is a possible but not a definitely proven cause for psychophysical somatosensory losses observed in their population. Additionally, the relatively simple psychophysical measures used in this work should be followed by more rigorous measures of the same population.     

Analysis of <Emphasis Type="Italic">Chromobacterium</Emphasis> sp. natural isolates from different Brazilian ecosystems

Background  

Chromobacterium violaceum is a free-living bacterium able to survive under diverse environmental conditions. In this study we evaluate the genetic and physiological diversity of Chromobacterium sp. isolates from three Brazilian ecosystems: Brazilian Savannah (Cerrado), Atlantic Rain Forest and Amazon Rain Forest. We have analyzed the diversity with molecular approaches (16S rRNA gene sequences and amplified ribosomal DNA restriction analysis) and phenotypic surveys of antibiotic resistance and biochemistry profiles.     

Plastome sequences of the subgenus Passiflora reveal highly divergent genes and specific evolutionary features

Plant Molecular Biology - Phylogenetic aspects, hotspots of nucleotide divergence, highly divergent genes, and specific RNA editing sites have been identified and characterized in the plastomes of...     

Natural Transmission and Experimental Models of SARS-CoV-2 Infection in Animals

Since the World Health Organization declared COVID-19 a pandemic in March 2020, millions of people have contracted SARS-CoV-2 and died from the infection. Several domestic and wild species have contracted the disease as well. From the beginning, scientists have been working to develop vaccines and establish therapies that can prevent disease development and improve the clinical outcome in infected people. To understand various aspects of viral pathogenesis and infection dynamics and to support preclinical evaluation of vaccines and therapeutics, a diverse number of animal species have been evaluated for use as models of the disease and infection in humans. Here, we discuss natural SARS-CoV-2 infection of domestic and captive wild animals, as well as the susceptibility of several species to experimental infection with this virus.

In December 2019, several health facilities in China reported cases of patients with pneumonia of unknown cause. Epidemiologic studies linked the majority of the affected patients with a seafood and wet-animal wholesale market in Wuhan, China.⁹⁴ The patients presented with fever, cough, and chest discomfort; 2 of the first 3 patients recovered, whereas the remaining one died. RNA extracted from the bronchoalveolar-lavage fluid of one patient was sequenced, and a viral sequence that had 85% identity with a SARS-related coronavirus isolated from a bat was identified. The same specimen was used for viral isolation, and the isolate was originally named 2019-nCoV. Genomic and phylogenetic analysis revealed similarities of the newly identified virus with bat coronaviruses and differences from severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV). The newly isolated virus belongs to a clade within the subgenus Sarbecovirus and differs from SARS-CoV and other SARS-related virus strains. Because the sequence identity in the 1ab open reading frame (conserved replicase domain) was less than 90% between 2019-nCoV and other betacoronaviruses, the virus was classified as a novel betacoronavirus, subgenus Sarbecovirus, family Coronaviridae.⁸⁴ The virus has since been officially renamed by the International Committee on Taxonomy of Viruses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with the disease caused by SARS-CoV-2 called COVID-19.¹⁷ As of 13 September 2021, more than 330 million cases of COVID-19 have occurred, and the disease has claimed more than 4.6 million human lives worldwide.⁸⁶SARS-CoV-2 uses angiotensin-converting enzyme 2 (ACE2) as the cellular receptor for virus binding.³⁴ The interaction between the virus spike protein and the host-cell ACE2 protein is mediated by the receptor binding domain (RBD) present in the spike protein. The RBD of the spike protein is highly variable among coronaviruses, and is under constant selection pressure. The affinity of the RBD of the spike protein with the cellular receptor determines the host range of coronaviruses.²⁵ Unlike the spike protein of SARS-CoV, the spike protein of SARS-CoV-2 is preactivated by the proprotein convertase furin prior to cell entry; the cell-surface protease transmembrane serine protease 2 and lysosomal cathepsin protease also participate in cell entry. The SARS-CoV-2 RBD binds to human ACE2 (hACE2) with higher affinity than does SARS-CoV. In contrast, the spike protein as a whole has lower affinity for hACE2, suggesting that the SARS-CoV-2 RBD provides a way to evade the immune system while still allowing efficient cell entry.^66,67The current coronavirus outbreak represents the third transmission of coronaviruses from animals to humans in the last 2 decades. In 2002, an outbreak of SARS-CoV in China caused 916 deaths (case fatality rate of 11%).^12,21 In 2012, another related coronavirus, Middle East Respiratory Syndrome coronavirus (MERS-CoV), emerged in Middle Eastern countries, with a mortality rate of 34%.^86,88 Several studies on the evolution of these viruses^18,25,26 and more recently on SARS-CoV-2¹ point to bats as the origin of infection for all 3 viruses.As for SARS-CoV and MERS-CoV, SARS-CoV-2 likely moved from bat reservoirs to a yet-unknown intermediate host and then to humans.^1,92 Masked civet cats and dromedary camels have been identified as the intermediate host for SARS-CoV and MERS-CoV, respectively.^73,89 Notably, several animal species seem to be naturally susceptible to SARS-CoV-2 infection, mainly due to the highly conserved nature of the ACE2 protein among diverse animal species, especially mammals. Pangolins,⁴⁴ dogs⁵⁸ and snakes⁴⁶ were under investigation as potential intermediate hosts for SARS-CoV-2. However, the animal species that enabled transmission to humans has yet to be determined. Natural infections have been reported in dogs, domestic cats, wild felids, gorillas, minks, ferrets, and white-tailed deer.^{3,14,22,28,50,54,55,72} (One source, Chandler JC and colleagues has not been peer reviewed). Several studies have been conducted to establish animal models for SARS-CoV-2 infection, including hACE2 mice, hamsters, NHP, cats, and ferrets.In this review, we discuss the natural occurrence of SARS-CoV-2 in animals and available animal models of SARS-CoV-2 infection and pathogenesis.     

Evaluation of Strongyloides stercoralis infection in patients with HTLV-1

Introduction: Individuals infected with the human T-lymphotropic virus type 1 (HTLV-1) may present severe and disseminated forms of Strongyloides stercoralis infection with low therapeutic response.Objective: To investigate the S. stercoralis infection and the seroprevalence of IgG anti-S. stercoralis antibodies in individuals infected with HTLV-1 attending the Reference Center for HTLV-1 (CHTLV) in Salvador, Bahia, Brazil.Materials and methods: We conducted a cross-sectional study in 178 HTLV-1-infected individuals treated at the HTLV specialized center between January, 2014, and December, 2018. The parasitological diagnosis of S. stercoralis was performed using the Hoffman, Pons and Janer, agar plate culture, and Baermann-Morais methods. The IgG anti-S. stercoralis detection was performed using an in house enzyme-linked immunosorbent assay (ELISA). The HTLV-1 infection was diagnosed using a commercial ELISA and confirmed by Western blot.Results: The frequency of S. stercoralis infection was 3.4% (6/178). Individuals infected with S. stercoralis from rural areas (50.0%; 3/6) also showed S. stercoralis hyperinfection (>3,000 larvae/ gram of feces). The frequency of circulating anti-S. stercoralis IgG antibodies was 20.8% (37/178). Conclusions: HTLV-1-infected people living in precarious sanitary conditions are more prone to develop severe forms of S. stercoralis infection. Considering the high susceptibility and unfavorable outcome of the infection in these individuals, the serological diagnosis for S. stercoralis should be considered when providing treatment.     

Structural analysis of SARS-Cov-2 nonstructural protein 1 polymorphisms found in the Brazilian Amazon

The coronavirus disease COVID-19 has been the cause of millions of deaths worldwide. Among the SARS-CoV-2 proteins, the non-structural protein 1 (NSP1) has great importance during the virus infection process and is present in both alpha and beta-CoVs. Therefore, monitoring of NSP1 polymorphisms is crucial in order to understand their role during infection and virus-induced pathogenicity. Herein, we analyzed how mutations detected in the circulating SARS-CoV-2 in the population of the city of Manaus, Amazonas state, Brazil could modify the tertiary structure of the NSP1 protein. Three mutations were detected in the SARS-CoV-2 NSP1 gene: deletion of the amino acids KSF from positions 141 to 143 (delKSF), SARS-CoV-2, lineage B.1.195; and two substitutions, R29H and R43C, SARS-CoV-2 lineage B.1.1.28 and B.1.1.33, respectively. The delKSF was found in 47 samples, whereas R29H and R43C were found in two samples, one for each mutation. The NSP1 structures carrying the mutations R43C and R29H on the N-terminal portion (e.g. residues 10 to 127) showed minor backbone divergence compared to the Wuhan model. However, the NSP1 C-terminal region (residues 145 to 180) was severely affected in the delKSF and R29H mutants. The intermediate variable region (residues 144 to 148) leads to changes in the C-terminal region, particularly in the delKSF structure. New investigations must be carried out to analyze how these changes affect NSP1 activity during the infection. Our results reinforce the need for continuous genomic surveillance of SARS-CoV-2 to better understand virus evolution and assess the potential impact of the viral mutations on the approved vaccines and future therapies.     

Domestic use of a disclosing solution for denture hygiene: a randomised trial

doi:10.1111/j.1741‐2358.2009.00309.x
Domestic use of a disclosing solution for denture hygiene: a randomised trial Objectives: The purpose of this study was to investigate the effect of the domestic use of a disclosing agent for denture hygiene. Materials and methods: Completely edentulous participants wearing maxillary dentures were randomly assigned to one of the three intervention groups: (1) Follow‐up only (control; n = 12); (2) Oral and denture hygiene instructions (n = 10); (3) Instructions associated with the home use of a disclosing agent (1% neutral red; n = 10). Biofilm coverage area (%) over internal and external surfaces of the maxillary denture was assessed at baseline and after 14 and 90 days. Data were evaluated by generalised estimating equations based on score tests (α = 0.05). Results: The participants presented low changes for areas of biofilm coverage (14 days (%): internal: GI = 1.4 ± 0.9; GII = 1.5 ± 1.3; GIII = ?0.4 ± 0.9; external: GI = 1.4 ± 1.5; GII = 1.5 ± 1.4; GIII = ?0.4 ± 0.9; 90 days (%): internal: GI = 2.0 ± 0.9; GII = 2.2 ± 1.4; GIII = 0.3 ± 1.0; external: GI = 2.1 ± 1.4; GII = 2.2 ± 1.5; GIII = 0.3 ± 0.9). Changes were similar for the three groups (p = 0.293) and were not influenced by the test time (p = 0.218). Conclusion: It can be concluded that the home use of a disclosing agent for denture hygiene does not improve the removal of the biofilm, particularly for patients with adequate oral hygiene habits.     

High resolution localization of cruzipain and Ssp4 in Trypanosoma cruzi by replica staining label fracture

Summary— The replica staining label fracture technique was used to analyse the distribution of cruzipain and Ssp4 in Trypanosoma cruzi. Intense labeling for the two proteins was seen on the E fracture face of amastigote forms. Gold particles did not co-localize with the intramembranous particles. Labeling was abolished by previous treatment of the parasites with phospholipase C from Trypanosoma brucei, which removes glycosylphosphatidyl inositol (GPI) anchored proteins. These observations suggest that cruzipain and Ssp4 are attached to the parasite surface via a GPI anchor.     

Host Modulation by a Parasite: How Leishmania infantum Modifies the Intestinal Environment of Lutzomyia longipalpis to Favor Its Development

Some reports have described the interference of Leishmania on sand flies physiology, and such behavior most likely evolved to favor the development and transmission of the parasite. Most of these studies showed that Leishmania could modulate the level of proteases in the midgut after an infective blood meal, and decreased proteolytic activity is indeed beneficial for the development of promastigotes in the gut of sand flies. In the present study, we performed a detailed investigation of the intestinal pH in Lutzomyia longipalpis females naturally infected with Leishmania infantum and investigated the production of trypsin by these insects using different approaches. Our results allowed us to propose a mechanism by which these parasites interfere with the physiology of L. longipalpis to decrease the production of proteolytic enzymes. According to our hypothesis L. infantum promastigotes indirectly interfere with the production of trypsin by modulating the mechanism that controls the intestinal pH via the action of a yet non-identified substance released by promastigote forms inside the midgut. This substance is not an acid, whose action would be restrict on to release H⁺ to the medium, but is a substance that is able to interfere with midgut physiology through a mechanism involving pH control. According to our hypothesis, as the pH decreases, the proteolytic enzymes efficiency is also reduced, leading to a decline in the supply of amino acids to the enterocytes: this decline reduces the stimulus for protease production because it is regulated by the supply of amino acids, thus leading to a delay in digestion.