RESUMO
BACKGROUND: Thyroid cancer is the most common endocrine malignancy. Current therapies are successful, however some patients progress to therapeutically refractive disease. The immunotherapeutic potential of the CXCL8-chemokine/CXCR2-chemokine-receptor system is currently being explored in numerous human cancers. This study aimed to evaluate if the targeting of CXCR2 by its selective antagonist, AZD5069, could modulate CXCL8-mediated pro-tumorigenic effects in thyroid-cancer (TC) cells in vitro. METHODS: Normal human primary thyroid cells (NHT) and TC cell lines TPC-1 (RET/PTC), BCPAP, 8505C and 8305C (BRAFV600e) were treated with AZD5069 (100 pM-10 µM) over a time-course. Viability and proliferation were assessed by WST-1 and crystal violet assays. CXCL8 and CXCR2 mRNA were evaluated by RT-PCR. CXCL8-protein concentrations were measured in cell culture supernatants by ELISA. CXCR2 on cell surface was evaluated by flow-cytometry. Cell-migration was assessed by trans-well-migration chamber-system. RESULTS: AZD5069 exerted negligible effects on cell proliferation or viability. AZD5069 significantly reduced CXCR2, (but not CXCL8) mRNAs in all cell types. CXCR2 was reduced on the membrane of some TC cell lines. A significant reduction of the CXCL8 secretion was found in TPC-1 cells (basal-secretion) and NHT (TNFα-induced secretion). AZD5069 significantly reduced basal and CXCL8-induced migration in NHT and different TC cells. CONCLUSIONS: Our findings confirm the involvement of the CXCL8/CXCR2-axis in promoting pro-tumorigenic effects in TC cells, further demonstrating its immunotherapeutic significance in human cancer.
RESUMO
Vascular smooth muscle cells (VSMC) play a critical role in the development and pathogenesis of intimal hyperplasia indicative of restenosis and other vascular diseases. Fragile-X related protein-1 (FXR1) is a muscle-enhanced RNA binding protein whose expression is increased in injured arteries. Previous studies suggest that FXR1 negatively regulates inflammation, but its causality in vascular disease is unknown. In the current study, RNA-sequencing of FXR1-depleted VSMC identified many transcripts with decreased abundance, most of which were associated with proliferation and cell division. mRNA abundance and stability of a number of these transcripts were decreased in FXR1-depleted hVSMC, as was proliferation (P < 0.05); however, increases in beta-galactosidase (P < 0.05) and γH2AX (P < 0.01), indicative of senescence, were noted. Further analysis showed increased abundance of senescence-associated genes with FXR1 depletion. A novel SMC-specific conditional knockout mouse (FXR1SMC/SMC) was developed for further analysis. In a carotid artery ligation model of intimal hyperplasia, FXR1SMC/SMC mice had significantly reduced neointima formation (P < 0.001) after ligation, as well as increases in senescence drivers p16, p21, and p53 compared with several controls. These results suggest that in addition to destabilization of inflammatory transcripts, FXR1 stabilized cell cycle-related genes in VSMC, and absence of FXR1 led to induction of a senescent phenotype, supporting the hypothesis that FXR1 may mediate vascular disease by regulating stability of proliferative mRNA in VSMC.
Assuntos
Músculo Liso Vascular , Doenças Vasculares , Animais , Camundongos , Artérias Carótidas/metabolismo , Proliferação de Células , Células Cultivadas , Modelos Animais de Doenças , Hiperplasia/patologia , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/metabolismo , Neointima/metabolismo , RNA Mensageiro/metabolismo , Doenças Vasculares/patologiaRESUMO
BACKGROUND: A more severe course of COVID-19 was associated with low levels of Vitamin D (VitD). Moreover in vitro data showed that VitD up-regulates the mRNA of the Angiotensin Converting Enzyme 2 (ACE-2), the SARS-COV-2 receptor in different type of cells. ACE-2 is expressed in several type of tissues including thyroid cells, on which its mRNA was shown to be up-regulated by interferon-gamma (IFN-γ). The aim of the present study was to investigate if treatment with VitD alone or in combination with IFN-γ would increase ACE-2 both at mRNA and protein levels in primary cultures of human thyrocytes. MATERIALS AND METHODS: Primary thyroid cell cultures were treated with VitD and IFN-γ alone or in combination for 24 h. ACE-2 mRNA levels were measured by Real-time Polymerase Chain Reaction (RT-PCR). The presence of ACE-2 on thyroid cell membrane was assessed by immunocytochemistry basally and after the previous mentioned treatments. RESULTS: ACE-2 mRNA levels increased after treatment with VitD and IFN-γ alone. The combination treatment (VitD + IFN-γ) showed an additive increase of ACE-2-mRNA. Immunocytochemistry experiments showed ACE-2 protein on thyroid cells membrane. ACE-2 expression increased after treatment with VitD and IFN-γ alone and further increased by the combination treatment with VitD + IFN-γ. CONCLUSIONS: VitD would defend the body by SARS-COV2 both by regulating the host immune defense and by up-regulating of the expression of the ACE-2 receptor. The existence of a co-operation between VitD and IFN-γ demonstrated in other systems is supported also for ACE-2 up-regulation. These observations lead to an increased interest for the potential therapeutic benefits of VitD supplementation in COVID-19.
Assuntos
Enzima de Conversão de Angiotensina 2 , Tratamento Farmacológico da COVID-19 , Humanos , Interferon gama/metabolismo , Interferon gama/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Viral , SARS-CoV-2 , Glândula Tireoide/metabolismo , Vitamina D/metabolismo , Vitamina D/farmacologia , Vitaminas/metabolismoRESUMO
CASE PRESENTATION: We describe a case of a patient who presented with a mildly symptomatic, giant myelolipoma which was excised by laparoscopic approach without complications. INTRODUCTION AND IMPORTANCE: Adrenal myelolipoma (AML) is a rare tumour composed by fat and myeloid tissues. Usually it is asymptomatic, so the diagnosis is mostly incidental. It is generally located in the right adrenal gland, but it can also be found bilaterally. If its size exceeds 10 cm it is defined as a "giant myelolipoma"; in this case its treatment of choice would be adrenalectomy with an open surgical approach. CLINICAL DISCUSSION: Patient's signs and symptoms were mild pain in the right hypochondrium and a positive right Giordano's sign. The mass was detected by a contrast-enhanced CT scan. Once excised it measured 16 cm. CONCLUSION: Laparoscopic adrenalectomy for giant myelolipoma is a safe approach if performed by an expert surgeon, with low risk of bleeding and a better outcome for the patient.
RESUMO
In this study, we have looked for an optimum media glucose concentration and compared glucose consumption in three vascular cell types, endothelial cells (ECs), vascular smooth muscle cells (VSMCs), and adventitial fibroblasts (AFs) with or without angiotensin II (AngII) stimulation. In a subconfluent 6-well experiment in 1 mL DMEM with a standard low (100 mg/dL), a standard high (450 mg/dL), or a mixed middle (275 mg/dL) glucose concentration, steady and significant glucose consumption was observed in all cell types. After 48-h incubation, media that contained low glucose was reduced to almost 0 mg/dL, media that contained high glucose remained significantly higher at â¼275 mg/dL, and media that contained middle glucose remained closer to physiological range. AngII treatment enhanced glucose consumption in AFs and VSMCs but not in ECs. Enhanced extracellular acidification rate by AngII was also observed in AFs. In AFs, AngII induction of target proteins at 48 h varied depending on the glucose concentration used. In low glucose media, induction of glucose regulatory protein 78 or hexokinase II was highest, whereas induction of VCAM-1 was lowest. Utilization of specific inhibitors further suggests essential roles of angiotensin II type-1 receptor and glycolysis in AngII-induced fibroblast activation. Overall, this study demonstrates a high risk of hypo- or hyperglycemic conditions when standard low or high glucose media is used with vascular cells. Moreover, these conditions may significantly alter experimental outcomes. Media glucose concentration should be monitored during any culture experiments and utilization of middle glucose media is recommended for all vascular cell types.
Assuntos
Células Endoteliais/metabolismo , Glucose/metabolismo , Glucose/farmacologia , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/metabolismo , Animais , Aorta Torácica/efeitos dos fármacos , Aorta Torácica/metabolismo , Células Cultivadas , Relação Dose-Resposta a Droga , Células Endoteliais/efeitos dos fármacos , Humanos , Masculino , Músculo Liso Vascular/efeitos dos fármacos , Miócitos de Músculo Liso/efeitos dos fármacos , Ratos , Ratos Sprague-DawleyRESUMO
As many as 70% of cells in atherosclerotic plaque are vascular smooth muscle cell (VSMC) in origin, and pathways and proteins which regulate VSMC migration, proliferation, and phenotype modulation represent novel targets for rational drug design to reduce atherosclerotic vascular disease. In this volume of Clinical Science, Karle et al. demonstrate that tumor suppressor, promyelocytic leukemia protein (PML) plays an important role in regulation of VSMC phenotype and response to inflammatory stimuli (Clin Sci (2021) 135(7), 887-905; DOI: 10.1042/CS20201399). This important work demonstrates that PML, previously unrecognized as a participant in development of atherosclerosis, may represent a novel target for anti-atherosclerotic therapeutic modalities.
Assuntos
Aterosclerose , Placa Aterosclerótica , Aterosclerose/genética , Humanos , Músculo Liso Vascular , Miócitos de Músculo Liso , Proteína da Leucemia Promielocítica/genéticaRESUMO
Cardiovascular disease is the leading cause of morbidity and mortality in the Western and developing world, and the incidence of cardiovascular disease is increasing with the longer lifespan afforded by our modern lifestyle. Vascular diseases including coronary heart disease, high blood pressure, and stroke comprise the majority of cardiovascular diseases, and therefore represent a significant medical and socioeconomic burden on our society. It may not be surprising that these conditions overlap and potentiate each other when we consider the many cellular and molecular similarities between them. These intersecting points are manifested in clinical studies in which lipid lowering therapies reduce blood pressure, and anti-hypertensive medications reduce atherosclerotic plaque. At the molecular level, the vascular smooth muscle cell (VSMC) is the target, integrator, and effector cell of both atherogenic and the major effector protein of the hypertensive signal Angiotensin II (Ang II). Together, these signals can potentiate each other and prime the artery and exacerbate hypertension and atherosclerosis. Therefore, VSMCs are the fulcrum in progression of these diseases and, therefore, understanding the effects of atherogenic stimuli and Ang II on the VSMC is key to understanding and treating atherosclerosis and hypertension. In this review, we will examine studies in which hypertension and atherosclerosis intersect on the VSMC, and illustrate common pathways between these two diseases and vascular aging.
Assuntos
Aterosclerose/fisiopatologia , Hipertensão/fisiopatologia , Músculo Liso Vascular/metabolismo , Angiotensina II/metabolismo , Animais , Anti-Hipertensivos/uso terapêutico , Aterosclerose/metabolismo , Pressão Sanguínea/efeitos dos fármacos , Doenças Cardiovasculares/metabolismo , Células Cultivadas , Humanos , Hipercolesterolemia/metabolismo , Hiperlipidemias/metabolismo , Hipertensão/metabolismo , Músculo Liso Vascular/fisiologia , Miócitos de Músculo Liso/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
The pathology of traumatic brain injury (TBI) adversely affects many brain regions, often resulting in the development of comorbid psychiatric disorders including substance use disorders (SUD). Although traditionally thought to be an epidemic that predominantly affects males, recent clinical studies report females have higher rates of concussions and longer recovery times than males. Yet, how neurotrauma, particularly deep within the brain, between the sexes is differentially manifested remains largely unknown. The risk of TBI peaks during adolescence when neuronal networks that regulate reward behaviors are not fully developed. Previously, using the conditioned place preference (CPP) assay, we found that adolescent TBI increased susceptibility to the rewarding effects of cocaine in male mice. Further, we observed augmented inflammatory profiles, increased microglial phagocytosis of neuronal proteins, and decreased neuronal spine density in the NAc. Notably, the extent of sex differences in SUD susceptibility following TBI has not be investigated. Thus, here we ask the central question of whether the adolescent TBI-induced neuroinflammatory profile at reward centers is divergent in a sex-dependent manner. Using the CPP assay, we found that female mice with high levels of female sex hormones at the time of adolescent TBI demonstrated neuroprotection against increased sensitivity to the rewarding effects of cocaine. These studies also provide evidence of significantly reduced microglial activation and phagocytosis of neuronal proteins within the NAc of females. Overall, our results offer crucial insight into how adolescent TBI impacts the reward pathway in a sex depending manner that could explain a vulnerability to addiction-like behavior.
Assuntos
Comportamento Aditivo , Comportamento Animal , Lesões Encefálicas Traumáticas , Cocaína/farmacologia , Inibidores da Captação de Dopamina/farmacologia , Estradiol/metabolismo , Inflamação , Neuroproteção , Progesterona/metabolismo , Recompensa , Caracteres Sexuais , Animais , Comportamento Aditivo/imunologia , Comportamento Aditivo/metabolismo , Comportamento Aditivo/fisiopatologia , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Lesões Encefálicas Traumáticas/imunologia , Lesões Encefálicas Traumáticas/metabolismo , Modelos Animais de Doenças , Feminino , Inflamação/imunologia , Inflamação/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neuroproteção/imunologia , Neuroproteção/fisiologiaRESUMO
Host immunity plays a central and complex role in dictating tumour progression. Solid tumours are commonly infiltrated by a large number of immune cells that dynamically interact with the surrounding microenvironment. At first, innate and adaptive immune cells successfully cooperate to eradicate microcolonies of transformed cells. Concomitantly, surviving tumour clones start to proliferate and harness immune responses by specifically hijacking anti-tumour effector mechanisms and fostering the accumulation of immunosuppressive immune cell subsets at the tumour site. This pliable interplay between immune and malignant cells is a relentless process that has been concisely organized in three different phases: elimination, equilibrium and escape. In this review, we aim to depict the distinct immune cell subsets and immune-mediated responses characterizing the tumour landscape throughout the three interconnected phases. Importantly, the identification of key immune players and molecules involved in the dynamic crosstalk between tumour and immune system has been crucial for the introduction of reliable prognostic factors and effective therapeutic protocols against cancers.
Assuntos
Citocinas/imunologia , Imunidade Inata , Neoplasias/imunologia , Evasão Tumoral , Microambiente Tumoral/imunologia , Comunicação Celular/imunologia , Citocinas/genética , Regulação da Expressão Gênica , Humanos , Vigilância Imunológica , Imunoterapia/métodos , Células Matadoras Naturais/imunologia , Células Matadoras Naturais/patologia , Neoplasias/genética , Neoplasias/patologia , Neoplasias/terapia , Transdução de Sinais , Linfócitos T Citotóxicos/imunologia , Linfócitos T Citotóxicos/patologia , Linfócitos T Reguladores/imunologia , Linfócitos T Reguladores/patologia , Microambiente Tumoral/genéticaRESUMO
BACKGROUND: The aim of this study was to compare the outcome of an enhanced recovery after surgery (ERAS) pathway with traditional perioperative care in laparoscopic rectal resection. METHODS: A retrospective analysis of prospectively collected data was conducted. Single-center consecutive patients who underwent laparoscopic rectal surgery after an ERAS program were compared with patients who received traditional care over an 8-year period. Primary and total length of stay, and readmission, morbidity and mortality rates were analyzed. For ERAS group, the actual adherence to protocol was also evaluated. RESULTS: Two hundred and ninety-seven patients, 162 in the ERAS group and 135 in conventional care, were studied. Median primary and total length of stay were significantly shorter in the ERAS group (9 vs 12 days; p = 0.0001; 10 vs 12 days; p = 0.01; respectively). The ERAS group experienced a faster recovery of bowel function than the traditional care group (p = 0.0001). A similar morbidity rate was observed in the two groups (32.3 % in ERAS vs 36.1 % in traditional care p = 0.41). Readmission rates were 4.9 % in the ERAS versus 1.5 % in the traditional care group (p = 0.19). There was no mortality in either group. Overall mean compliance with the ERAS protocol was 85.7 % (range 54.4-100 %). CONCLUSIONS: The introduction of the ERAS protocol in laparoscopic rectal resection led to a reduction in primary and total length of hospital stay without an increase in morbidity or readmission rates when compared to traditional care.
Assuntos
Deambulação Precoce , Laparoscopia/reabilitação , Recuperação de Função Fisiológica , Neoplasias Retais/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos Clínicos , Feminino , Fidelidade a Diretrizes , Humanos , Intestino Grosso/fisiopatologia , Laparoscopia/efeitos adversos , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Readmissão do Paciente , Guias de Prática Clínica como Assunto , Estudos Retrospectivos , Fatores de TempoRESUMO
Mesenchymal stem cells (MSC) represent a promising therapeutic approach in many diseases in view of their potent immunomodulatory properties, which are only partially understood. Here, we show that the endothelium is a specific and key target of MSC during immunity and inflammation. In mice, MSC inhibit activation and proliferation of endothelial cells in remote inflamed lymph nodes (LNs), affect elongation and arborization of high endothelial venules (HEVs) and inhibit T-cell homing. The proteomic analysis of the MSC secretome identified the tissue inhibitor of metalloproteinase-1 (TIMP-1) as a potential effector molecule responsible for the anti-angiogenic properties of MSC. Both in vitro and in vivo, TIMP-1 activity is responsible for the anti-angiogenic effects of MSC, and increasing TIMP-1 concentrations delivered by an Adeno Associated Virus (AAV) vector recapitulates the effects of MSC transplantation on draining LNs. Thus, this study discovers a new and highly efficient general mechanism through which MSC tune down immunity and inflammation, identifies TIMP-1 as a novel biomarker of MSC-based therapy and opens the gate to new therapeutic approaches of inflammatory diseases.
Assuntos
Células Endoteliais/metabolismo , Linfonodos/citologia , Linfócitos/fisiologia , Células-Tronco Mesenquimais/fisiologia , Inibidor Tecidual de Metaloproteinase-1/metabolismo , Inibidores da Angiogênese , Animais , Técnicas de Transferência de Genes , Vetores Genéticos , Inflamação , Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/metabolismo , Camundongos , Inibidor Tecidual de Metaloproteinase-1/administração & dosagem , Inibidor Tecidual de Metaloproteinase-1/genética , Inibidor Tecidual de Metaloproteinase-1/farmacologiaRESUMO
BACKGROUND AND STUDY AIMS: This study was undertaken to compare the efficacy, side effects and patient acceptance of standard 4-liters polyethylene glycol (PEG) and 2 doses of sodium phosphate (NaP) solution for precolonoscopy colon cleansing. PATIENTS AND METHODS: A total of 182 patients were randomized to receive either standard 4-L PEG (88 patients) or 80 mL of NaP (94 patients) in a split regimen of two 40 mL doses separated by 24 h, prior to colonoscopic evaluation. The primary endpoint was the segmental assessment of colonic wall visualization. Secondary outcomes included percent of assumed preparation, and the patient tolerance and acceptability. RESULTS: A significantly higher completion rate was found in the NaP group compared to the PEG group (84.3% vs 62.9%; difference, 21.40%; 95% confidence interval [CI], 8.29% to 34.51%; p = 0.001). PEG solution caused more nausea than NaP solution (p = 0.024). Patient acceptance for bowel preparation with NaP was greater (p = 0.019). Adequate colon wall visualization was achieved in similar proportion of patients in both groups with exception of the descending colon, where NaP regimen was superior (72.0% vs 52.9%; difference, 19.10%; 95% CI, 5.20% to 33.00% ; p = 0.012). CONCLUSIONS: Two doses of NaP solution, taken 24 h and 12 h before colonoscopy, tend to guarantee superior results in colonic cleansing with respect to standard 4-liters PEG solution. Taking the second dose of NaP 24 h after the first dose reduces side effects and allows achieving a more satisfactory compliance of the patient.
Assuntos
Catárticos/administração & dosagem , Colonoscopia , Fosfatos/administração & dosagem , Polietilenoglicóis/administração & dosagem , Adolescente , Adulto , Idoso , Catárticos/efeitos adversos , Enema , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Aceitação pelo Paciente de Cuidados de Saúde , Fosfatos/efeitos adversos , Polietilenoglicóis/efeitos adversos , Irrigação TerapêuticaRESUMO
We present a rare case of intra-abdominal hemorrhage due to a ruptured pheochromocytoma. Our patient presented with signs of shock. By emergency surgery, an hemorrhagic pheochromocytoma of the left adrenal gland was removed. Recovery was uneventful. In cases of suspected hemorrhagic pheochromocytoma with severe shock, prompt surgery is mandatory and catecholamines administration may be crucial to resolve hypotension and guarantee an uneventful recovery.
Assuntos
Neoplasias das Glândulas Suprarrenais , Feocromocitoma , Choque Hemorrágico/etiologia , Neoplasias das Glândulas Suprarrenais/complicações , Neoplasias das Glândulas Suprarrenais/diagnóstico , Neoplasias das Glândulas Suprarrenais/cirurgia , Idoso , Catecolaminas/administração & dosagem , Tratamento de Emergência/métodos , Humanos , Masculino , Feocromocitoma/complicações , Feocromocitoma/diagnóstico , Feocromocitoma/cirurgia , Ruptura Espontânea , Resultado do TratamentoRESUMO
Diverticular disease is very frequent in Western countries; in 5% of the cases it is the cause of serious bleeding, haemodynamic instability and death. The authors report a case of 74 years old patient with severe lower gastrointestinal bleeding. She was in antiplatelet treatment with acetylsalicylic acid (100 mg/die) and clopidogrel (75 mg/die) for preventing the restenosis of medicated stents positioned to treat an acute coronary syndrome. At the same time the patient was under treatment for primary hypercholesterolemia with rosuvastatin (20 mg/die). The severe haemorrhage demanded haemodynamic stabilization, achieved by colloid infusion and blood transfusions. The bleeding continued; selective arteriography showed it's origin from the areas of the sigmoid and superior hemorrhoidal arteries. During the procedure, embolization of the inferior mesenteric artery using spiral type BALT was performed, with consequent bleeding interruption. Fifteen days after the embolization, a rectosigmoid colonoscopy showed a sigmoid diverticular disease. The treatment with acetylsalicylic acid and clopidogrel has surely contributed to the severity of the hemorrhage. Recent experimental and clinical evidence suggests a possible antiplatelet effect of the statins.
Assuntos
Divertículo/complicações , Divertículo/diagnóstico , Hemorragia Gastrointestinal/etiologia , Inibidores da Agregação Plaquetária/administração & dosagem , Inibidores da Agregação Plaquetária/efeitos adversos , Doenças do Colo Sigmoide/complicações , Doenças do Colo Sigmoide/diagnóstico , Síndrome Coronariana Aguda/terapia , Idoso , Aspirina/administração & dosagem , Aspirina/efeitos adversos , Clopidogrel , Reestenose Coronária/prevenção & controle , Stents Farmacológicos , Feminino , Fluorbenzenos/administração & dosagem , Fluorbenzenos/efeitos adversos , Hemorragia Gastrointestinal/induzido quimicamente , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/administração & dosagem , Inibidores de Hidroximetilglutaril-CoA Redutases/efeitos adversos , Hipercolesterolemia/tratamento farmacológico , Pirimidinas/administração & dosagem , Pirimidinas/efeitos adversos , Rosuvastatina Cálcica , Sulfonamidas/administração & dosagem , Sulfonamidas/efeitos adversos , Ticlopidina/administração & dosagem , Ticlopidina/efeitos adversos , Ticlopidina/análogos & derivadosRESUMO
There have been millions of people found to have AIDS. Death rates from AIDS have declined 15% to 20% in the past 5 years. However, nearly 75000 people will die with AIDS in this year. Patients with AIDS are also at risk for developing both Aids-defining cancers, such as Kaposi's sarcoma and non-Hodgkin lymphoma, and non-Aids-defining cancers and opportunistic infections. In patients with advanced Aids, the Cytomegalovirus is a frequent cause of chorioretinitis, pneumonitis, chronic perineal ulcerations and oesophagitis. It has been involved in endocrine, bone marrow, central nervous system and kidney abnormalities. CMV infection of the small bowel accounts for only 4.3% of all cytomegalovirus infection of the GI tract (large bowel 47%, duodenum 21,7%, stomach 17,4%); isolated cases of small bowel perforation due to CMV have been reported in AIDS patients, and all but one patient died. The Authors report a rare case of an HIV-positive young man with gastroenteric Cytomegalovirus infection responsible for generalized peritonitis from multiple perforations.
Assuntos
Infecções Oportunistas Relacionadas com a AIDS/virologia , Infecções por Citomegalovirus/etiologia , Gastroenteropatias/virologia , Soropositividade para HIV/complicações , Peritonite/virologia , Adulto , Evolução Fatal , Humanos , MasculinoRESUMO
Eukaryotic mRNAs that contain premature stop codons are degraded more rapidly than their wild-type counterparts, a phenomenon termed "nonsense-mediated mRNA decay" (NMD) or "mRNA surveillance." Functions of six previously described Caenorhabditis elegans genes, smg-1 through smg-6, are required for NMD. Whereas nonsense mutant mRNAs are unstable in smg(+) genetic backgrounds, such mRNAs have normal stability in smg(-) backgrounds. Previous screens for smg mutations have likely not identified all genes involved in NMD, but efforts to identify additional smg genes are limited by the fact that almost 90% of smg mutations identified in genome-wide screens are alleles of smg-1, smg-2, or smg-5. We describe a modified screen for smg mutations that precludes isolating alleles of smg-1, smg-2, and smg-5. Using this screen, we have identified and cloned smg-7, a previously uncharacterized gene that we show is required for NMD. smg-7 is predicted to encode a novel protein that contains an acidic carboxyl terminus and two probable tetratricopeptide repeats. We provide evidence that smg-7 is cotranscribed with the previously characterized gene lin-45 and show that null alleles of smg-7 confer a temperature-sensitive defect in NMD.
Assuntos
Proteínas de Caenorhabditis elegans , Caenorhabditis elegans/genética , Códon de Terminação/genética , Proteínas de Helminto/genética , Biossíntese de Proteínas , RNA Mensageiro/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Regulação da Expressão Gênica , Dados de Sequência Molecular , Mutação , Alinhamento de SequênciaRESUMO
Nonsense mutant mRNAs are unstable in all eucaryotes tested, a phenomenon termed nonsense-mediated mRNA decay (NMD) or mRNA surveillance. Functions of the seven smg genes are required for mRNA surveillance in Caenorhabditis elegans. In Smg(+) genetic backgrounds, nonsense-mutant mRNAs are unstable, while in Smg(-) backgrounds such mRNAs are stable. Previous work has demonstrated that the elevated level of nonsense-mutant mRNAs in Smg(-) animals can influence the phenotypic effects of heterozygous nonsense mutations. Certain nonsense alleles of a muscle myosin heavy chain gene are recessive in Smg(+) backgrounds but strongly dominant in Smg(-) backgrounds. Such alleles probably express disruptive myosin polypeptide fragments whose abundance is elevated in smg mutants due to elevation of mRNA levels. We report here that mutations in a variety of C. elegans genes are strongly dominant in Smg(-), but recessive or only weakly dominant in Smg(+) backgrounds. We isolated 32 dominant visible mutations in a Smg(-) genetic background and tested whether their dominance requires a functional NMD system. The dominance of 21 of these mutations is influenced by NMD. We demonstrate, furthermore, that in the case of myosin, the dominant-negative effects of nonsense alleles are likely to be due to expression of N-terminal nonsense-fragment polypeptides, not to mistranslation of the nonsense codons. mRNA surveillance, therefore, may mitigate potentially deleterious effects of many heterozygous germline and somatic nonsense or frame-shift mutations. We also provide evidence that smg-6, a gene previously identified as being required for NMD, performs essential function(s) in addition to its role in NMD.
Assuntos
Caenorhabditis elegans/genética , Genes Dominantes , Proteínas de Helminto/genética , RNA Mensageiro/fisiologia , Animais , Caenorhabditis elegans/fisiologia , Deleção de Genes , Regulação da Expressão Gênica , Genes Letais , Masculino , Mutação , Cadeias Pesadas de Miosina/genética , FenótipoRESUMO
Saccharomyces cerevisiae is dimorphic and switches from a yeast form to a pseudohyphal (PH) form when starved for nitrogen. PH cells are elongated, bud in a unipolar manner, and invade the agar substrate. We assessed the requirements for actin in mediating the dramatic morphogenetic events that accompany the transition to PH growth. Twelve "alanine scan" alleles of the single yeast actin gene (ACT1) were tested for effects on filamentation, unipolar budding, agar invasion, and cell elongation. Some act1 mutations affect all phenotypes, whereas others affect only one or two aspects of PH growth. Tests of intragenic complementation among specific act1 mutations support the phenotypic evidence for multiple actin functions in filamentous growth. We present evidence that interaction between actin and the actin-binding protein fimbrin is important for PH growth and suggest that association of different actin-binding proteins with actin mediates the multiple functions of actin in filamentous growth. Furthermore, characterization of cytoskeletal structure in wild type and act1/act1 mutants indicates that PH cell morphogenesis requires the maintenance of a highly polarized actin cytoskeleton. Collectively, this work demonstrates that actin plays a central role in fungal dimorphism.
Assuntos
Actinas/fisiologia , Proteínas dos Microfilamentos , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/crescimento & desenvolvimento , Actinas/química , Actinas/genética , Alelos , Divisão Celular/genética , Polaridade Celular/genética , Citoesqueleto/química , Citoesqueleto/genética , Citoesqueleto/fisiologia , Genes Dominantes/fisiologia , Teste de Complementação Genética , Glicoproteínas de Membrana/fisiologia , Modelos Moleculares , Mutagênese Sítio-Dirigida , Nitrogênio/deficiência , Saccharomyces cerevisiae/genéticaRESUMO
The conditional lethal mutations ts8 and h8 are located in fda, the gene encoding aldolase, and they inhibit RNA synthesis upon shift to the nonpermissive temperature. We demonstrate that both mutations preferentially inhibit stable RNA synthesis and that this inhibition occurs at the level of transcription initiation. The susceptibility of a promoter to the inhibitory effects of ts8 is correlated with the ability of the promoter to be growth rate regulated. This effect is independent of relA and spoT function. Inhibition is dependent upon glucose metabolism past the generation of glucose-6-phosphate; however, the mechanism of this effect is unknown.