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1.
Clin Radiol ; 76(12): 889-895, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34654544

RESUMO

It is important that clinical radiologists understand and appreciate the minimally invasive surgery (MIS) options available to surgeons. Operative technologies are constantly evolving, and accurate, informed interpretation of clinical imaging is essential for optimum surgical management. Concurrent advancements in both MIS and radiological staging have certainly improved treatment decisions and outcomes. This article outlines the history, current concepts, evolving techniques, and future prospects of MIS as it pertains to colorectal cancer surgery.


Assuntos
Neoplasias Colorretais/cirurgia , Procedimentos Cirúrgicos Minimamente Invasivos , Neoplasias Colorretais/diagnóstico por imagem , Neoplasias Colorretais/patologia , Humanos , Procedimentos Cirúrgicos Robóticos
2.
J Dairy Sci ; 104(6): 7026-7038, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33773792

RESUMO

Claw horn lesions (CHL) are the result of a failing of the functional anatomy of the hoof in dairy cows. The digital cushion is understood to be a vital structure in the prevention of CHL. Claw horn lesions have previously been shown to lead to pathological change to the pedal bone; however, their effects on the digital cushion are unknown. The primary aim of this study was to examine associations between the history of CHL through an animal's life and the structure of the digital cushion at slaughter using magnetic resonance imaging. The retrospective cohort study resulted in the scanning of 102 pairs of hindfeet, collected from adult Holstein dairy cows culled from a research herd, using a 3-Tesla research-grade magnetic resonance imaging scanner. Volume and fat measurements were calculated for each digital cushion within each claw from a modified Dixon Quant sequence. Animal-level variables were constructed around the animals' lactating lifetime, with lameness scores and body condition score collected at least every 2 wk. The combined volume of digital cushion in the lateral claws was used as the outcome variable in multivariable linear models. The volume of the digital cushion was negatively associated with the number of lameness events or CHL recorded. Furthermore, animals with body condition score >3, culled later in lactation, or of a greater body weight were more likely to have a higher volume of digital cushion in the lateral claws. We propose that the observations made in the current study are the effects of a range of factors broadly associated with genetic, developmental, and disease-related inputs. Our understanding of how we can select for genetically more robust animals and how we can precondition the hoof before first calving needs to be improved to reduce the risk of future CHL in adult dairy cattle. Furthermore, understanding optimal treatment regimens and their effect on hoof anatomy may reduce the recurrence of CHL in the current lactation and future lactations.


Assuntos
Doenças dos Bovinos , Doenças do Pé , Animais , Bovinos , Feminino , Doenças do Pé/veterinária , Lactação , Coxeadura Animal , Imageamento por Ressonância Magnética/veterinária , Estudos Retrospectivos
3.
Nature ; 502(7472): 524-7, 2013 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-24153304

RESUMO

Of several dozen galaxies observed spectroscopically that are candidates for having a redshift (z) in excess of seven, only five have had their redshifts confirmed via Lyman α emission, at z = 7.008, 7.045, 7.109, 7.213 and 7.215 (refs 1-4). The small fraction of confirmed galaxies may indicate that the neutral fraction in the intergalactic medium rises quickly at z > 6.5, given that Lyman α is resonantly scattered by neutral gas. The small samples and limited depth of previous observations, however, makes these conclusions tentative. Here we report a deep near-infrared spectroscopic survey of 43 photometrically-selected galaxies with z > 6.5. We detect a near-infrared emission line from only a single galaxy, confirming that some process is making Lyman α difficult to detect. The detected emission line at a wavelength of 1.0343 micrometres is likely to be Lyman α emission, placing this galaxy at a redshift z = 7.51, an epoch 700 million years after the Big Bang. This galaxy's colours are consistent with significant metal content, implying that galaxies become enriched rapidly. We calculate a surprisingly high star-formation rate of about 330 solar masses per year, which is more than a factor of 100 greater than that seen in the Milky Way. Such a galaxy is unexpected in a survey of our size, suggesting that the early Universe may harbour a larger number of intense sites of star formation than expected.

5.
J Fish Dis ; 41(1): 61-66, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28921572

RESUMO

Syncytial hepatitis (SHT) is an emerging viral disease of tilapia characterized by significant morbidity and mortality. This study aimed to establish the production-level risk factors associated with presence and severity of SHT. Production factors were analysed during multiple outbreaks of SHT that occurred between 2011 and 2013 on a single tilapia farm in Ecuador and compared with the year 2010 before the SHT outbreaks. Relative risks, t tests, modified Poisson and forward stepwise linear regression analyses were performed using EPIINFO™. Compared to other strains, Chitralada had an elevated risk of SHT [RR = 2.1 (95%CI 1.8-2.4)]. Excessive mortality associated with the presence (and severity) of SHT increased by 611 (365), 6,814 (5,768) and 388 (340) deaths per 100,000 fry when stocking density, dissolved oxygen and pond production cycles were raised by 1 fish/m2 , 1 mg/L and 1 cycle, respectively. Excessive mortality associated with the presence (and severity) of SHT decreased by 337 (258) and 1,354 (1,025) deaths per 100,000 when stocking weight and water temperature increased by 1 g and 1°C, respectively. Time (season and stocking year) was not significantly associated with SHT. This study shows that some production factors increase the risk incidence and severity of SHTon a farm.


Assuntos
Aquicultura/métodos , Ciclídeos/virologia , Doenças dos Peixes/virologia , Hepatite Viral Animal/epidemiologia , Infecções por Orthomyxoviridae/veterinária , Animais , Ciclídeos/genética , Surtos de Doenças/veterinária , Equador , Doenças dos Peixes/epidemiologia , Doenças dos Peixes/mortalidade , Células Gigantes/virologia , Orthomyxoviridae , Fatores de Risco , Temperatura
6.
Vet Pathol ; 54(1): 164-170, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27511312

RESUMO

Using transmission electron microscopy (TEM), the presented work expands on the ultrastructural findings of an earlier report on "syncytial hepatitis," a novel disease of tilapia (SHT). Briefly, TEM confirmed the presence of an orthomyxovirus-like virus within the diseased hepatocytes but not within the endothelium. This was supported by observing extracellular and intracellular (mostly intraendosomal), 60-100 nm round virions with a trilaminar capsid containing up to 7 electron-dense aggregates. Other patterns noted included enveloped or filamentous virions and virion-containing cytoplasmic membrane folds, suggestive of endocytosis. Patterns atypical for orthymyxovirus included the formation of syncytia and the presence of virions within the perinuclear cisternae (suspected to be the Golgi apparatus). The ultrastructural morphology of SHT-associated virions is similar to that previously reported for tilapia lake virus (TiLV). A genetic homology was investigated using the available reverse transcriptase polymerase chain reaction (RT-PCR) probes for TiLV and comparing clinically sick with clinically normal fish and negative controls. By RT-PCR analysis, viral nucleic acid was detected only in diseased fish. Taken together, these findings strongly suggest that a virus is causally associated with SHT, that this virus shares ultrastructural features with orthomyxoviruses, and it presents with partial genetic homology with TiLV (190 nucleotides).


Assuntos
Doenças dos Peixes/virologia , Hepatite Viral Animal/virologia , Hepatócitos/virologia , Infecções por Orthomyxoviridae/veterinária , Tilápia/virologia , Vírion/ultraestrutura , Animais , Hepatite Viral Animal/patologia , Hepatócitos/patologia , Hepatócitos/ultraestrutura , Masculino , Microscopia Eletrônica de Transmissão/veterinária , Orthomyxoviridae/genética , Infecções por Orthomyxoviridae/patologia , Infecções por Orthomyxoviridae/virologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária
7.
J Fish Dis ; 40(5): 609-620, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-27523398

RESUMO

The social media network Facebook™ was used to gather information on the occurrence and geographical distribution of dusky grouper dermatitis, a skin lesion affecting the dusky grouper, Epinephelus marginatus. Dusky grouper are common targets for spear fishermen in the Mediterranean and by monitoring spearfishing activity in Libyan waters, it was possible to document skin lesions from their entries on Facebook. Thirty-two Facebook accounts and 8 Facebook groups posting from 23 Libyan coastal cities provided a retrospective observational data set comprising a total of 382 images of dusky grouper caught by spearfishing between December 2011 and December 2015. Skin lesions were observable on 57/362 fish, for which images were of sufficient quality for analysis, giving a minimal prevalence for lesions of 15.75%. Only dusky grouper exceeding an estimated 40 cm total length exhibited lesions. The ability to collect useful data about the occurrence and geographical distribution of pathological conditions affecting wild fish using social media networks demonstrates their potential utility as a tool to support epidemiological studies and monitor the health of populations of aquatic animals. To our knowledge, this represents the first time that such an approach has been applied for assessing health in a wild population of fish.


Assuntos
Bass , Dermatite/veterinária , Monitoramento Ambiental/métodos , Doenças dos Peixes/diagnóstico , Mídias Sociais , Animais , Dermatite/classificação , Dermatite/diagnóstico , Dermatite/epidemiologia , Monitoramento Ambiental/instrumentação , Doenças dos Peixes/classificação , Doenças dos Peixes/epidemiologia , Líbia/epidemiologia , Vigilância da População , Estudos Retrospectivos , Mídias Sociais/estatística & dados numéricos
8.
Parasitology ; 143(4): 389-400, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26817785

RESUMO

The public health threat posed by zoonotic Plasmodium knowlesi appears to be growing: it is increasingly reported across South East Asia, and is the leading cause of malaria in Malaysian Borneo. Plasmodium knowlesi threatens progress towards malaria elimination as aspects of its transmission, such as spillover from wildlife reservoirs and reliance on outdoor-biting vectors, may limit the effectiveness of conventional methods of malaria control. The development of new quantitative approaches that address the ecological complexity of P. knowlesi, particularly through a focus on its primary reservoir hosts, will be required to control it. Here, we review what is known about P. knowlesi transmission, identify key knowledge gaps in the context of current approaches to transmission modelling, and discuss the integration of these approaches with clinical parasitology and geostatistical analysis. We highlight the need to incorporate the influences of fine-scale spatial variation, rapid changes to the landscape, and reservoir population and transmission dynamics. The proposed integrated approach would address the unique challenges posed by malaria as a zoonosis, aid the identification of transmission hotspots, provide insight into the mechanistic links between incidence and land use change and support the design of appropriate interventions.


Assuntos
Ecologia/tendências , Macaca/parasitologia , Malária/transmissão , Doenças dos Macacos/parasitologia , Plasmodium knowlesi , Zoonoses/parasitologia , Animais , Sudeste Asiático/epidemiologia , Culicidae/parasitologia , Demografia , Reservatórios de Doenças/parasitologia , Atividades Humanas , Humanos , Insetos Vetores/parasitologia , Malária/epidemiologia , Malária/parasitologia , Modelos Biológicos , Doenças dos Macacos/epidemiologia , Doenças dos Macacos/transmissão , Plasmodium knowlesi/patogenicidade , Plasmodium knowlesi/fisiologia , Fatores de Risco , Zoonoses/epidemiologia , Zoonoses/transmissão
9.
J Fish Dis ; 39(12): 1457-1466, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27144368

RESUMO

In the period 2013-2015, wild dusky grouper, Epinephelus marginatus (Lowe), caught in Libyan coastal waters and ranging in size from 42 to 92 cm in total length, were observed to have distinctive skin lesions of unknown aetiology. Histopathologically, the lesions comprised a multifocal, unilateral or bilateral dermatitis, involving the epidermis, superficial dermis and scale pockets, and sometimes, in severe cases, the hypodermis. Severe lesions had marked epidermal spongiosis progressing to ulceration. Healing was observed in some fish. Bacteria and fungi could be isolated from severe lesions, although they were not seen histopathologically in early-stage lesions. By contrast, metazoan parasite eggs were observed in the dermis and epidermis of some fish with mild and moderate dermatitis. Unidentified gravid digenean trematode parasites carrying similar eggs were also seen within the blood vessels of the deep and superficial dermis. The cause of this distinctive condition, termed dusky grouper dermatitis (DGD), and its potential impact upon already threatened Mediterranean wild dusky grouper populations and upon cultured grouper more widely have yet to be established.


Assuntos
Bass , Dermatite/veterinária , Doenças dos Peixes/patologia , Animais , Dermatite/epidemiologia , Dermatite/etiologia , Dermatite/patologia , Espécies em Perigo de Extinção , Doenças dos Peixes/epidemiologia , Doenças dos Peixes/microbiologia , Doenças dos Peixes/parasitologia , Líbia/epidemiologia
10.
J Fish Dis ; 39(1): 13-29, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25399660

RESUMO

Streptococcus agalactiae infections in fish are predominantly caused by beta-haemolytic strains of clonal complex (CC) 7, notably its namesake sequence type (ST) 7, or by non-haemolytic strains of CC552, including the globally distributed ST260. In contrast, CC23, including its namesake ST23, has been associated with a wide homeothermic and poikilothermic host range, but never with fish. The aim of this study was to determine whether ST23 is virulent in fish and to identify genomic markers of fish adaptation of S. agalactiae. Intraperitoneal challenge of Nile tilapia, Oreochromis niloticus (Linnaeus), showed that ST260 is lethal at doses down to 10(2) cfu per fish, whereas ST23 does not cause disease at 10(7) cfu per fish. Comparison of the genome sequence of ST260 and ST23 with those of strains derived from fish, cattle and humans revealed the presence of genomic elements that are unique to subpopulations of S. agalactiae that have the ability to infect fish (CC7 and CC552). These loci occurred in clusters exhibiting typical signatures of mobile genetic elements. PCR-based screening of a collection of isolates from multiple host species confirmed the association of selected genes with fish-derived strains. Several fish-associated genes encode proteins that potentially provide fitness in the aquatic environment.


Assuntos
Ciclídeos , Doenças dos Peixes/microbiologia , Genoma Bacteriano , Infecções Estreptocócicas/veterinária , Streptococcus agalactiae/patogenicidade , Animais , Bovinos , DNA Bacteriano/química , DNA Bacteriano/isolamento & purificação , Loci Gênicos/genética , Humanos , Filogenia , Focas Verdadeiras/microbiologia , Inoculações Seriadas/veterinária , Infecções Estreptocócicas/microbiologia , Streptococcus agalactiae/classificação , Streptococcus agalactiae/genética , Virulência
11.
Proc Biol Sci ; 282(1817): 20151453, 2015 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-26468242

RESUMO

The rhythm of life on earth is shaped by seasonal changes in the environment. Plants and animals show profound annual cycles in physiology, health, morphology, behaviour and demography in response to environmental cues. Seasonal biology impacts ecosystems and agriculture, with consequences for humans and biodiversity. Human populations show robust annual rhythms in health and well-being, and the birth month can have lasting effects that persist throughout life. This review emphasizes the need for a better understanding of seasonal biology against the backdrop of its rapidly progressing disruption through climate change, human lifestyles and other anthropogenic impact. Climate change is modifying annual rhythms to which numerous organisms have adapted, with potential consequences for industries relating to health, ecosystems and food security. Disconcertingly, human lifestyles under artificial conditions of eternal summer provide the most extreme example for disconnect from natural seasons, making humans vulnerable to increased morbidity and mortality. In this review, we introduce scenarios of seasonal disruption, highlight key aspects of seasonal biology and summarize from biomedical, anthropological, veterinary, agricultural and environmental perspectives the recent evidence for seasonal desynchronization between environmental factors and internal rhythms. Because annual rhythms are pervasive across biological systems, they provide a common framework for trans-disciplinary research.


Assuntos
Ecossistema , Abastecimento de Alimentos , Periodicidade , Estações do Ano , Agricultura , Animais , Biodiversidade , Mudança Climática , Humanos , Plantas
12.
Opt Express ; 22(7): 7773-82, 2014 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-24718153

RESUMO

Having in mind parametric amplification of surface plasmon polaritons (SPPs) as the final goal, we took the first step and studied in the Kretschmann geometry a simpler nonlinear optical process - second harmonic generation (SHG) enhanced by SPPs propagating at the interface between gold film and 2-methyl-4-nitroaniline (MNA). The experimentally demonstrated SHG efficiency was nearly 10(6) times larger than the one reported previously in the SPP system with different nonlinear optical material. The experimentally measured nonlinear conversion efficiency is estimated to be sufficient for parametric amplification of surface plasmon polaritons at ultra-short laser pumping.

13.
Colorectal Dis ; 16(5): O176-81, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24299144

RESUMO

AIM: The Rapid Access Diagnosis and Remedy (RADAR) clinic combines 2-week wait (TWW) specialist consultation with 'straight-to-test' flexible sigmoidoscopy (FS) for left-sided 'red-flag' TWW criteria (excluding right-sided mass or iron-deficiency anaemia). The study aims were to determine the effectiveness of RADAR in differentiating colorectal cancer from benign disease and to evaluate the need for whole colonic investigation (WCI) following FS, in symptomatic patients. METHOD: Prospectively collated data of all RADAR patients from November 2005 to November 2009 were analysed, excluding patients referred internally for a FS. The local histology database was later interrogated to detect any missed cancers. RESULTS: Of 1690 patients (729 men; median (range) age: 68 (18-96) years) assessed in RADAR, 84 were excluded. Colorectal cancer (CRC) was diagnosed in 117 (7.3%). Eighty-seven cancers were diagnosed on the day of attendance and a further 13 within a week (88.9% overall). Two patients after a cancer-free FS were found to have a right-sided CRC on WCI (0.24%) and one synchronous cancer was found. No patient with a cancer-free FS having a WCI was subsequently found to have CRC at a median of 35 (12-58) months. CONCLUSION: Flexible sigmoidoscopy, in the context of an endoscopy unit TWW clinic, allows same-day diagnosis of most patients referred with left-sided symptoms, and immediate reassurance and treatment of most benign diagnoses. For these patients, the use of routine WCI following a cancer-free FS does not appear to be beneficial. Adopting this system would significantly reduce the number of barium enemas and colonoscopies currently performed.


Assuntos
Assistência Ambulatorial/estatística & dados numéricos , Neoplasias Colorretais/diagnóstico , Encaminhamento e Consulta/estatística & dados numéricos , Sigmoidoscopia , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Assistência Ambulatorial/organização & administração , Sulfato de Bário , Colonoscopia , Neoplasias Colorretais/complicações , Meios de Contraste , Defecação , Divertículo do Colo/complicações , Divertículo do Colo/diagnóstico , Enema , Feminino , Hemorragia Gastrointestinal/etiologia , Hemorroidas/complicações , Hemorroidas/diagnóstico , Humanos , Masculino , Pessoa de Meia-Idade , Encaminhamento e Consulta/organização & administração , Fatores de Tempo , Listas de Espera , Adulto Jovem
14.
Tech Coloproctol ; 18(11): 1113-6, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25154752

RESUMO

Melanoma of the anorectum represents <2 % of all anorectal cancers and 0.3 % of all primary melanomas. Prognosis is poor, and optimal surgical management is controversial. This series details the surgical management of patients with anorectal melanoma presenting between 2002 and 2013 to the Queen Elizabeth Hospital in Birmingham, UK, a tertiary referral centre for colorectal disease. A retrospective review of patient notes, histology reports, and clinical letters was used to assess perioperative course and long-term outcome of all surgical methods. Eight patients with a median age of 65.5 presented with primary anorectal melanoma during the study period. Six cases were staged as T4 pre-operatively, with two referred as incompletely excised polyps. All eight patients underwent abdominoperineal excision of the rectum (APER), with the most recent four cases undergoing extralevator APER. Clear resection margins were achieved in three out of the four patients in the extralevator APER group with no nodal spread detected at histological assessment. Extralevator APER appears to be feasible and safe in the treatment of melanoma of the anorectum, with 75 % medium-term survival (median 38 months) in selected patients. As it is known that clear margins at surgery are associated with disease-free survival, the wider excision margin at the level of the pelvic floor offered by extralevator APER could result in more favourable surgical outcomes in this prognostically poor malignancy.


Assuntos
Abdome/cirurgia , Procedimentos Cirúrgicos do Sistema Digestório/métodos , Melanoma/cirurgia , Períneo/cirurgia , Neoplasias Retais/cirurgia , Adulto , Idoso , Biópsia , Colonoscopia , Intervalo Livre de Doença , Feminino , Seguimentos , Humanos , Imageamento por Ressonância Magnética , Masculino , Melanoma/diagnóstico , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Projetos Piloto , Prognóstico , Neoplasias Retais/diagnóstico , Estudos Retrospectivos
16.
Ann R Coll Surg Engl ; 105(4): 314-322, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35486133

RESUMO

INTRODUCTION: The coronavirus disease 2019 (COVID-19) pandemic led to hospitals in the UK substituting face-to-face (FtF) clinics with virtual clinic (VC) appointments. We evaluated the use of virtual two-week wait (2-ww) lower gastrointestinal (LGI) clinic appointments, conducted using telephone calls at a district general hospital in England. METHODS: Patients undergoing index outpatient 2-ww LGI clinic assessment between 1 June 2019 and 31 October 2019 (FtF group) and 1 June 2020 and 31 October 2020 (VC group) were identified. Relevant data were obtained using electronic patient records. Compliance with national cancer waiting time targets was assessed. Environmental and financial impact analyses were performed. RESULTS: In total, 1,531 patients were analysed (median age=70, male=852, 55.6%). Of these, 757 (49.4%) were assessed virtually via telephone; the remainder were seen FtF (n=774, 50.6%). Ninety-two (6%, VC=44, FtF=48) patients had malignant pathology and 64 (4.2%) had colorectal cancer (CRC); of these, 46 (71.9%, VC=26, FtF=20) underwent treatment with curative intent. The median waiting times to index appointment, investigation and diagnosis were significantly lower following VC assessment (p<0.001). The cancer detection rates (p=0.749), treatments received (p=0.785) and median time to index treatment for CRC patients (p=0.156) were similar. A significantly higher proportion of patients were seen within two weeks of referral in the VC group (p<0.001). VC appointments saved patients a total of 9,288 miles, 0.7 metric tonnes of CO2 emissions and £7,482.97. Taxpayers saved £80,242.00 from VCs. No formal complaints were received from patients or staff in the VC group. CONCLUSION: Virtual 2-ww LGI clinics were effective, safe and were associated with tangible environmental and financial benefits.


Assuntos
COVID-19 , Neoplasias Colorretais , Humanos , Masculino , Idoso , Encaminhamento e Consulta , COVID-19/epidemiologia , Telefone , Agendamento de Consultas , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/terapia
17.
J Evol Biol ; 25(3): 452-60, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22221693

RESUMO

We investigated the fitness consequences of specialization in an organism whose host choice has an immense impact on human health: the African malaria vector Anopheles gambiae s.s. We tested whether this mosquito's specialism on humans can be attributed to the relative fitness benefits of specialist vs. generalist feeding strategies by contrasting their fecundity and survival on human-only and mixed host diets consisting of blood meals from humans and animals. When given only one blood meal, An. gambiae s.s. survived significantly longer on human and bovine blood, than on canine or avian blood. However, when blood fed repeatedly, there was no evidence that the fitness of An. gambiae s.s. fed a human-only diet was greater than those fed generalist diets. This suggests that the adoption of generalist host feeding strategies in An. gambiae s.s. is not constrained by intraspecific variation in the resource quality of blood from other available host species.


Assuntos
Adaptação Biológica/fisiologia , Fenômenos Fisiológicos da Nutrição Animal/fisiologia , Anopheles/fisiologia , Interações Hospedeiro-Parasita/fisiologia , Animais , Bovinos , Cães , Comportamento Alimentar/fisiologia , Fertilidade/fisiologia , Humanos , Modelos de Riscos Proporcionais , Especificidade da Espécie , Análise de Sobrevida
18.
Nature ; 441(7092): 463-8, 2006 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-16688183

RESUMO

When massive stars exhaust their fuel, they collapse and often produce the extraordinarily bright explosions known as core-collapse supernovae. On occasion, this stellar collapse also powers an even more brilliant relativistic explosion known as a long-duration gamma-ray burst. One would then expect that these long gamma-ray bursts and core-collapse supernovae should be found in similar galactic environments. Here we show that this expectation is wrong. We find that the gamma-ray bursts are far more concentrated in the very brightest regions of their host galaxies than are the core-collapse supernovae. Furthermore, the host galaxies of the long gamma-ray bursts are significantly fainter and more irregular than the hosts of the core-collapse supernovae. Together these results suggest that long-duration gamma-ray bursts are associated with the most extremely massive stars and may be restricted to galaxies of limited chemical evolution. Our results directly imply that long gamma-ray bursts are relatively rare in galaxies such as our own Milky Way.

19.
J Fish Dis ; 35(11): 799-808, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22913764

RESUMO

Studies on the ultrastructural morphogenesis of viruses give an insight into how the host cell mechanisms are utilized for new virion synthesis. A time course examining salmonid alphavirus 1 (SAV 1) assembly was performed by culturing the virus on Chinook salmon embryo cells (CHSE-214). Different stages of viral replication were observed under electron microscopy. Virus-like particles were observed inside membrane-bound vesicles as early as 1 h following contact of the virus with the cells. Membrane-dependent replication complexes were observed in the cytoplasm of the cells, with spherules found at the periphery of late endosome-like vacuoles. The use of intracellular membranes for RNA replication is similar to other positive-sense single-stranded RNA (+ssRNA) viruses. The number of Golgi apparatus and associated vacuoles characterized by 'fuzzy'-coated membranes was greater in virus-infected cells. The mature enveloped virions started to bud out from the cells at approximately 24 h post-infection. These observations suggest that the pathway used by SAV 1 for the generation of new virus particles in vitro is comparable to viral replication observed with mammalian alphaviruses but with some interesting differences.


Assuntos
Alphavirus/fisiologia , Alphavirus/ultraestrutura , Animais , Linhagem Celular , Microscopia Eletrônica de Transmissão , Salmonidae/virologia , Replicação Viral
20.
J Fish Dis ; 35(1): 19-27, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22103767

RESUMO

This is the first pathological description of 'scale drop syndrome' (SDS) in Asian seabass, Lates calcarifer Bloch. Cumulative mortality was estimated at 40-50%. The vasculitis in all major organs including the skin and associated tissue necrosis was distinctive. The dermis overlying scale beds was often necrotic and associated with scale loss. Necrosis of splenic ellipsoids, renal glomeruli and choroid rete glands of eye were further hallmarks of a disease with systemic vascular involvement. The brain was not spared vascular damage, and the resulting multifocal encephalomalacia probably accounts for the spiral swimming behaviour in some affected fish. Other lesions included accentuated hepatic lobulation and gastric gland necrosis. Nuclear chromatin margination and karyolysis in hepatocytes, renal tubular epithelium and gastric and intestinal epithelium suggest specific targeting of cells. Basophilic cytoplasmic inclusions were present in spleen, kidney, liver, heart and choroid rete, but they were not prominent. Using transmission electron microscopy, two morphological forms of virions were observed: single- and double-enveloped hexagonal virions. Based on size and morphology, these virions resemble iridovirus or herpesvirus. The cause of SDS is unknown, but the pathological changes, especially the vasculitis, suggest an infectious aetiology, possibly viral.


Assuntos
Bass , Doenças dos Peixes/patologia , Animais , Ásia , Doenças dos Peixes/mortalidade , Doenças dos Peixes/virologia , Microscopia Eletrônica de Transmissão , Síndrome , Vírion/ultraestrutura
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