Modulation of persistent current in graphene quantum rings.

We investigate the effect of long-range impurity potentials on the persistent current of graphene quantum rings in the presence of an uniform perpendicular magnetic field. The impurity potentials are modeled as finite regions of the ring with a definite length. We show that, due to the relativistic and massless character of the charge carriers in graphene, the effect of such non-uniform potentials on the energy spectrum and on the persistent current of the rings can be reliably modeled by assuming a non-perturbed ring and including an additional phase due to the interaction of the charge carriers with the potential. In addition, the results show the presence of localized states in the impurity regions. Moreover, we show that for the case of a potential created by a p-n-p junction, the persistent current can be modulated by controlling the voltage at the junction.

Milk Contamination by Mycobacterium tuberculosis Complex, Implications for Public Health in Amazonas, Brazil.

ABSTRACT: In Brazil, contamination of raw milk with Mycobacterium tuberculosis complex (MTC) has been reported in several states. The highest rate of consumption of raw milk and its derivatives in Brazil occurs in Amazonas. This state also has the highest prevalence of tuberculosis in both humans and livestock. We assessed the contamination of cow's milk and buffalo's milk with MTC in Amazonas, focusing on Mycobacterium bovis, the species most commonly found in cattle and buffalo. In 2019, 250 samples of raw milk (91 from cattle, 159 from buffalo) were collected before processing from three milk plants in the state of Amazonas. The samples were placed into 21 pools and analyzed using shotgun metagenomic sequencing and taxonomic classification with Kraken 2 and MegaBLAST. To confirm the identity of mycobacterial species found, BLASTN was used to identify specific genomic positions in the TbD1 and RD1 regions and flanking RD4 region. MTC genetic material was identified in all pools of raw milk. Genetic material consistent with M. bovis was identified in seven pools of raw milk (1 from cattle, 6 from buffalo). Buffalo's milk had significantly higher MTC reads than did cow's milk. The common practice of consumption of raw milk and its derivatives in Amazonas presents a risk to public health. Urgent measures to prevent transmission of foodborne tuberculosis are needed in the Amazon region. Greater efforts and resources also should be directed toward elimination of bovine tuberculosis in cattle and buffalo herds in Amazonas and the rest of Brazil.

Gate potential-controlled current switching in graphene Y-junctions.

In this work we investigate the ballistic transport of electrons through three-terminal graphene-based devices. The system consists of a Y-shaped junction formed by three armchair-edged graphene nanoribbons with a rectangular gate potential applied to one of the output branches, whereby current control can be established by the controlling of the refractive index in graphene p-n junctions. Transport properties are obtained by using the Landauer-Büttiker formalism and the tight-binding model within the nearest-neighbor approximation, which allows the calculation of the conductance as function of the Fermi energy, the applied potential, and the system size, as well as the current density. The results demonstrate that the applied electric field can tune the current transmission between the input and two output leads and, consequently, the proposed system acts as a current switch.

Differentiation of canine adipose mesenchymal stem cells into insulin-producing cells: comparison of different culture medium compositions.

The aim of this study was to differentiate canine adipose-derived mesenchymal stem cells (ADMSCs) into insulin-producing cells by using culture media with different compositions to determine the most efficient media. Stem cells isolated from the fat tissues close to the bitch uterus were distributed into 6 groups: (1) Dulbecco's modified Eagle medium (DMEM)-high glucose (HG), ß-mercaptoethanol, and nicotinamide; (2) DMEM-HG, ß-mercaptoethanol, nicotinamide, and exendin-4; (3) DMEM-HG, ß-mercaptoethanol, nicotinamide, exendin-4, B27, nonessential amino acids, and l-glutamine; (4) DMEM-HG, ß-mercaptoethanol, and nicotinamide (for the initial 8-d period), and DMEM-HG, ß-mercaptoethanol, nicotinamide, exendin-4, B27, nonessential amino acids, l-glutamine, and basic fibroblast growth factor (for the remaining 8-d period); (5) DMEM-HG and fetal bovine serum; and (6) DMEM-low glucose and fetal bovine serum (standard control group). Adipose-derived mesenchymal stem cells from groups 1 to 5 gradually became round in shape and gathered in clusters. These changes differed between the groups. In group 3, the cell clusters were apparently more in numbers and gathered as bigger aggregates. Dithizone staining showed that groups 3 and 4 were similar in terms of the mean area of each aggregate stained for insulin. However, only in group 4, the number of insulin aggregates and the total area of aggregates stained were significantly bigger than in the other groups. The mRNA expression of PDX1, BETA2, MafA, and Insulin were also confirmed in all the groups. We conclude that by manipulating the composition of the culture medium it is possible to induce canine ADMSCs into insulin-producing cells, and the 2-staged protocol that was used promoted the best differentiation.

Current modulation in graphene p-n junctions with external fields.

In this work we describe a proposal for a graphene-based nanostructure that modulates electric current even in the absence of a gap in the band structure. The device consists of a graphene p-n junction that acts as a Veselago lens that focuses ballistic electrons on the output lead. Applying external (electric and magnetic) fields changes the position of the output focus, reducing the transmission. Such device can be applied to low power field effect transistors, which can benefit from graphene's high electronic mobility.

Tumor carcinoide na vesícula biliar em cão / Carcinoid gallbladder tumor in a dog

Carcinoid is a neoplasia that arises from dispersed cells of the neuroendocrine system. This tumor is uncommon in animals, and its occurrence in the gallbladder is rare. A male Basset Hound dog's corpse was taken to the Univerdade Federal de Minas Gerais to be analyzed by the Veterinary Pathology sector, without a description of its previous history. Necropsy revealed the presence of pale oral, ocular and penile mucous membranes. The gallbladder had a thickened wall and a dilated lumen, which was filled with dark and lumpy bile. Its mucosa had a whitish-red nodule, with solid and friable areas. Microscopically, there was a focal neoplastic proliferation, which wasn't encapsulated and had imprecise limits, which cells were distributed in a solid pattern and separated by a delicate fibrovascular stroma. The neoplastic cells presented oval or round shaped nucleus, which had a chromatin predominantly loose, and one or two nucleoli. Their cytoplasm was moderately abundant, and in most of the cells it was eosinophilic, granular, and had well-defined limits. Using the Grimelius coloration, neoplastic cells' cytoplasmic granules stained brownish or black, confirming the neuroendocrine origin of the neoplasia. Based on the macroscopic and microscopic findings, the diagnosis of a gallbladder carcinoid was established.(AU)

Modelo de indução de osteoporose em coelhas - avaliação radiográfica / Rabbit osteoporosis induction model - radiographic evaluation

In order to establish a bone loss induction model in rabbits to study osteoporosis, 18 rabbits underwent ovariectomy and received methylprednisolone 1mg/kg intramuscularly on alternate days for two weeks. Immediately before ovariectomy up to 42 days after methylprednisolone administration, radiographs of the right olecranon were taken in the mediolateral position to evaluate the radiographic optical density. Before the induction of osteoporosis, rabbits presented mean values of radiographic density of 2.305mm Al and at 42 days of 1.575mm Al. The values obtained were submitted to ANOVA for repeated measures that revealed a significant drop (P< 0.001) in the density over time, proving that the induction was able to trigger bone loss of these animals. With this, it can be affirmed that the adopted protocol was enough to provoke a significant bone loss, characterizing a valid model for the study of new treatments for osteoporosis.(AU)

Humane endpoint in mice by Brazilian researchers in the vaccine sector / Ponto final humanitário em camundongos aplicado por pesquisadores brasileiros da área de vacinas

The application of a humane endpoint (HE) for mice in vaccine trials and further challenging tasks with lethal samples is necessary to reduce or prevent pain and suffering in these animals, and is a refinement of the 3R policy enforced for animal testing in both national and international scenarios. In order to investigate the application of HE in Brazil, researchers from the vaccine sector have answered a questionnaire about their research profile, their usage of HE and their knowledge of its defining criteria, monitoring of animals, staff training, and euthanasia methods employed. The main results revealed that researchers failed to recognise the very concept of HE as well as when to apply it. In addition, the Institutional Animal Care and Use Committees (IACUCs) failed upon giving their approval to the trials. HE is an important refinament of animal testing policy, and these results highlight the need for a clear pre-established definition of when and how it should be implemented in order to ensure more effective application. Furthermore, it is important to clarify the ethics involved and the commitment of both the research teams and IACUCs to animal welfare.(AU)

A aplicação de um ponto final humanitário (PFH) em experimentos com vacinação e posterior desafio com amostras letais em camundongos é necessária para diminuir ou impedir a dor e o sofrimento desses animais, constituindo refinamento de acordo com a política dos 3Rs, vigente em âmbito nacional e internacional, no cenário da experimentação animal. A fim de investigar a aplicação de PFH no Brasil, foi enviado um questionário para pesquisadores da área de vacinas, com perguntas sobre perfil do pesquisador, aplicação de PFH e critérios para sua definição, monitoramento dos animais, treinamento da equipe e métodos de eutanásia empregados. Os principais resultados revelaram que há falhas tanto em reconhecer o conceito quanto em aplicar o PFH, por parte dos pesquisadores, e que as CEUAs também falharam ao aprovar tais experimentos. Chama-se atenção para o fato de que o PFH é um importante refinamento e para a necessidade de definição prévia de PFH e sua aplicação, assim como para a importância do esclarecimento da questão ética envolvida e do necessário compromisso das equipes de pesquisa e das CEUAs com o bem-estar animal.(AU)

Detection of Leishmania spp. in Bats from an Area of Brazil Endemic for Visceral Leishmaniasis.

The multihost parasites Leishmania spp. infect a broad range of wild mammalian species including bats. Several species of bats have adapted to a variety of food resources and shelters in urban areas. This study aimed to detect Leishmania spp. DNA in bats present in forest fragments located in metropolitan areas endemic for leishmaniasis in Campo Grande, Mato Grosso do Sul (MS), Brazil. Blood samples were obtained from 80 individuals, including eight species of Phyllostomidae and one species of Vespertilionidae. Thirty of the 80 bats were positive for Leishmania spp. using conventional PCR, all belonging to the family Phyllostomidae. Eighteen samples tested by real-time PCR (qPCR) using specific primers for the kDNA of Leishmania infantum were positive. To the best of our knowledge, this is the first report detecting Leishmania spp. in Platyrrhinus incarum in addition to being the first reported detection of L. infantum in the bat species Phyllostomus discolor, Platyrrhinus lineatus, Artibeus planirostris and Artibeus lituratus. Our results show that bats can host Leishmania spp. in areas endemic for leishmaniasis, which must be taken into account in disease control operations by public health authorities.

The genomics of mycobacteria.

The species Mycobacterium bovis and Mycobacterium avium subspecies paratuberculosis are the causal agents, respectively, of tuberculosis and paratuberculosis in animals. Both mycobacteria, especially M. bovis, are also important to public health because they can infect humans. In recent years, this and the impact of tuberculosis and paratuberculosis on animal production have led to significant advances in knowledge about both pathogens and their host interactions. This article describes the contribution of genomics and functional genomics to studies of the evolution, virulence, epidemiology and diagnosis of both these pathogenic mycobacteria.

Les mycobactéries Mycobacterium bovis et Mycobacterium avium subsp. paratuberculosis sont les agents étiologiques de la tuberculose et de la paratuberculose, respectivement. En outre, les deux mycobactéries (mais plus particulièrement M. bovis) peuvent infecter l'être humain et jouent donc un rôle en santé publique. En raison de cette importance et des effets de la tuberculose et de la paratuberculose sur la production animale, de grands efforts ont été déployés pour faire avancer nos connaissances sur ces deux agents pathogènes et sur leurs interactions avec leurs hôtes. Les auteurs décrivent la contribution de la génomique et de la génomique fonctionnelle dans les études sur l'évolution, la virulence, l'épidémiologie et le diagnostic de ces deux mycobactéries pathogènes.

Las especies Mycobacterium bovis y Mycobacterium avium subsp. paratuberculosis son los agentes causales de la tuberculosis y la paratuberculosis en animales, respectivamente. Además, ambas micobacterias, pero fundamentalmente M. bovis, son importantes para la salud pública, ya que pueden infectar a los humanos. Debido a esto último y al impacto de la tuberculosis y la paratuberculosis en la producción animal, en los últimos años se ha producido un avance significativo en los conocimientos de ambos agentes patógenos y de la interacción con sus hospedadores. En este artículo describiremos la contribución de la genómica y la genómica funcional a los estudios de evolución, virulencia, epidemiología y diagnóstico de ambas micobacterias patógenas.

Action of phosphorylated mannanoligosaccharides on immune and hematological responses and fecal consistency of dogs experimentally infected with enteropathogenic Escherichia coli strains.

The therapeutic action of phosphorylated mannanoligosaccharides (MOS) was investigated regarding its prebiotic activity on enteropathogenic Escherichia coli (EPEC). Diarrhea was induced in dogs by experimental infection with EPEC strains. Then MOS was supplied once a day, in water for 20 days. Immunological (IgA and IgG), hematological (lymphocytes, neutrophils and monocytes) and bacteriological variables (PCR detection of the eae gene of EPEC recovered from stool culture), as well as occurrence of diarrhea were evaluated. All strains caused diarrhea at 24, 48 and 72 h after infection. PCR results indicated that E. coli isolated from stool culture of all infected animals had the eae gene. There was no significant difference among groups as to number of blood cells in the hemogram and IgA and IgG production. MOS was effective in recovering of EPEC-infected dogs since prebiotic-treated animals recovered more rapidly from infection than untreated ones (p < 0.05). This is an important finding since diarrhea causes intense dehydration and nutrient loss. The use of prebiotics for humans and other animals with diarrhea can be an alternative for the treatment and prophylaxis of EPEC infections.

Evidence for extensive genetic diversity and substructuring of the Babesia bovis metapopulation.

Babesia bovis is a tick-transmitted haemoprotozoan and a causative agent of bovine babesiosis, a cattle disease that causes significant economic loss in tropical and subtropical regions. A panel of nineteen micro- and minisatellite markers was used to estimate population genetic parameters of eighteen parasite isolates originating from different continents, countries and geographic regions including North America (Mexico, USA), South America (Argentina, Brazil), the Middle East (Israel) and Australia. For eleven of the eighteen isolates, a unique haplotype was inferred suggesting selection of a single genotype by either in vitro cultivation or amplification in splenectomized calves. Furthermore, a high genetic diversity (H = 0.780) over all marker loci was estimated. Linkage disequilibrium was observed in the total study group but also in sample subgroups from the Americas, Brazil, and Israel and Australia. In contrast, corresponding to their more confined geographic origin, samples from Israel and Argentina were each found to be in equilibrium suggestive of random mating and frequent genetic exchange. The genetic differentiation (F(ST)) of the total study group over all nineteen loci was estimated by analysis of variance (Θ) and Nei's estimation of heterozygosity (G(ST')) as 0.296 and 0.312, respectively. Thus, about 30% of the genetic diversity of the parasite population is associated with genetic differences between parasite isolates sampled from the different geographic regions. The pairwise similarity of multilocus genotypes (MLGs) was assessed and a neighbour-joining dendrogram generated. MLGs were found to cluster according to the country/continent of origin of isolates, but did not distinguish the attenuated from the pathogenic parasite state. The distant geographic origin of the isolates studied allows an initial glimpse into the large extent of genetic diversity and differentiation of the B. bovis population on a global scale.

Action of phosphorylated mannanoligosaccharides on immune and hematological responses and fecal consistency of dogs experimentally infected with enteropathogenic Escherichia coli strains

The therapeutic action of phosphorylated mannanoligosaccharides (MOS) was investigated regarding its prebiotic activity on enteropathogenic Escherichia coli (EPEC). Diarrhea was induced in dogs by experimental infection with EPEC strains. Then MOS was supplied once a day, in water for 20 days. Immunological (IgA and IgG), hematological (lymphocytes, neutrophils and monocytes) and bacteriological variables (PCR detection of the eae gene of EPEC recovered from stool culture), as well as occurrence of diarrhea were evaluated. All strains caused diarrhea at 24, 48 and 72 h after infection. PCR results indicated that E. coli isolated from stool culture of all infected animals had the eae gene. There was no significant difference among groups as to number of blood cells in the hemogram and IgA and IgG production. MOS was effective in recovering of EPEC-infected dogs since prebiotic-treated animals recovered more rapidly from infection than untreated ones (p < 0.05). This is an important finding since diarrhea causes intense dehydration and nutrient loss. The use of prebiotics for humans and other animals with diarrhea can be an alternative for the treatment and prophylaxis of EPEC infections.

Sirolimus as rescue therapy after liver transplantation.

UNLABELLED: Sirolimus has immunosuppressive properties and antitumor effects. It was prescribed in liver transplantation initially in association with calcineurin inhibitors because of its lower nephrotoxic and neurotoxic effects and its potential antitumor effects. The aim of this study was to analyze the use of sirolimus as rescue therapy for liver transplant patients. METHODS: We retrospectively analyzed all 15 patients treated with sirolimus from 2009 to 2011 among 150 liver transplantations. We analyzed pre- and postconversion data. With statistical analysis using the Student's t-test. RESULTS: Sirolimus was the immunosuppressant therapy in 15 of 150 (10%) patients. Their average age was 56.2 years (range, 42-69) including 9 men (60%). The mean time between liver transplantation and the introduction of sirolimus was 24.6 months (range, 1-120). Sirolimus remained as the sole medication for 4 patients (26.6%). The overall time of sirolimus thereby averaged 14.3 months (range, 1-18). The reasons for the introduction of sirolimus were acute rejection (n = 8; 53.3%), chronic rejection (n = 2; 13.3%), development of malignancy (n = 3; 20%) or prior hepatocellular carcinoma (n = 2; 13.3%). Among 9 patients who initiated sirolimus because of rejection, 7 (77.7%) showed improvement in serum liver enzymes. Among the 3 (33.3%) patients who displayed renal insufficiency before the introduction of sirolimus (creatinine level > 1.5 mg/dL) 1 showed improvement with a decrease of ≥50%. The average follow-up was 18 months (range, 1-36). The average sirolimus level during the first 3 months was 10.3 ng/mL (range, 6.1-19.3). All patients developed side effects such as anemia, hypertriglyceridemia, hypercholesterolemia, and infection. In conclusion, sirolimus was useful as rescue therapy.

Molecular frequency and isolation of cyst-forming coccidia from free ranging chickens in Bahia State, Brazil.

The Toxoplasmatinae parasites Toxoplasma gondii, Neospora caninum and Hammondia spp. have carnivores as definitive hosts that shed the parasite oocysts in their feces. Birds that feed directly from the soil, such as chickens, are exposed to infection and may serve as indicators of the presence of the parasite in the environment and as a source of infection for other animals. The aims of this study were to determine the frequency of infection by these parasites in free ranging chickens, to test whether chickens are intermediate hosts of Hammondia spp., and to isolate N. caninum from chickens. One hundred chickens, which were raised in contact to cattle and dogs, were bought in five towns located in Bahia, Brazil. Blood and tissues (brain and heart) were used for serology, molecular tests and bioassay in mice for parasite isolation. T. gondii DNA was detected in 29 chickens, and N. caninum DNA was observed in six animals. Hammondia spp. DNA was not detected in tissues from any chicken. Tissues from eight N. caninum seropositive chickens were bioassayed in interferon-gamma gene knockout mice, but the mice did not become infected; T. gondii was isolated from six of 14 seropositive chickens after bioassay in outbreed Swiss mice. The authors concluded that: chickens seem to be better hosts for T. gondii when compared to N. caninum, based on the molecular and bioassay results; Hammondia spp. probably does not infect chickens or is rarely found in this animal species.

Epidemiology of bovine anaplasmosis in dairy herds from Costa Rica.

Bovine anaplasmosis is endemic and occurs in almost all areas of livestock production of Costa Rica. The aim of this study was to determine the seroprevalence and risk factors of anaplasmosis in dairy farms of Costa Rica by the recombinant truncated MSP-5 (rMSP-5) enzyme-linked immunosorbent assay (ELISA). Serum samples were obtained from 733 cattle from 20 commercial dairy herds of Costa Rica. The overall seroprevalence was 37.2% and herd seroprevalence ranged from 20.0 to 72.0%. The age-specific seroprevalence was 49.3% in young and 33.4% in adult animals. The main risk factors associated with seroprevalence were season of occurrence of clinical cases (rainy season) (OR=22.8), presence of tabanids (OR=9.5) and stable flies (OR=6.2), stable flies control measures (OR=3.2), non-use of ear tattoos (OR=2.8), interval of veterinary visit (≤ 60 days) (OR=2.7), altitude of the farms (<800 masl) (OR=2.6) and age (<2 years) (OR=1.8). The results indicated that exposure of cattle to Anaplasma marginale is common in dairy herds of Costa Rica and endemic instability situation probably is due to inadequate vector control.

Molecular detection of anaplasma platys in a naturally-infected cat in Brazil

Following the accidental finding of inclusion bodies similar to Anaplasma platys in a stained blood smear from a cat, DNA analysis of the 16S rRNA gene was performed and 100 percent identity was found with different strains of A. platys. These data confirm that cats are susceptible to parasitism by A. platys.

Molecular detection of Anaplasma platys in a naturally-infected cat in Brazil.

Following the accidental finding of inclusion bodies similar to Anaplasma platys in a stained blood smear from a cat, DNA analysis of the 16S rRNA gene was performed and 100% identity was found with different strains of A. platys. These data confirm that cats are susceptible to parasitism by A. platys.

Genetic associations between carcass traits measured by real-time ultrasound and scrotal circumference and growth traits in Nelore cattle.

The aim of the present study was to evaluate the genetic correlations among real-time ultrasound carcass, BW, and scrotal circumference (SC) traits in Nelore cattle. Carcass traits, measured by real-time ultrasound of the live animal, were recorded from 2002 to 2004 on 10 farms across 6 Brazilian states on 2,590 males and females ranging in age from 450 to 599 d. Ultrasound records of LM area (LMA) and backfat thickness (BF) were obtained from cross-sectional images between the 12th and 13th ribs, and rump fat thickness (RF) was measured between the hook and pin bones over the junction between gluteus medius and biceps femoris muscles. Also, BW (n = 22,778) and SC (n = 5,695) were recorded on animals born between 1998 and 2003. The BW traits were 120, 210, 365, 450, and 550-d standardized BW (W120, W210, W365, W450, and W550), plus BW (WS) and hip height (HH) on the ultrasound scanning date. The SC traits were 365-, 450-, and 550-d standardized SC (SC365, SC450, and SC550). For the BW and SC traits, the database used was from the Nelore Breeding Program-Nelore Brazil. The genetic parameters were estimated with multivariate animal models and REML. Estimated genetic correlations between LMA and other traits were 0.06 (BF), -0.04 (RF), 0.05 (HH), 0.58 (WS), 0.53 (W120), 0.62 (W210), 0.67 (W365), 0.64 (W450 and W550), 0.28 (SC365), 0.24 (SC450), and 0.00 (SC550). Estimated genetic correlations between BF and with other traits were 0.74 (RF), -0.32 (HH), 0.19 (WS), -0.03 (W120), -0.10 (W210), 0.04 (W365), 0.01 (W450), 0.06 (W550), 0.17 (SC365 and SC450), and -0.19 (SC550). Estimated genetic correlations between RF and other traits were -0.41 (HH), -0.09 (WS), -0.13 (W120), -0.09 (W210), -0.01 (W365), 0.02 (W450), 0.03 (W550), 0.05 (SC365), 0.11 (SC450), and -0.18 (SC550). These estimates indicate that selection for carcass traits measured by real-time ultrasound should not cause antagonism in the genetic improvement of SC and BW traits. Also, selection to increase HH might decrease subcutaneous fat as correlated response. Therefore, to obtain animals suited to specific tropical production systems, carcass, BW, and SC traits should be considered in selection programs.