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1.
Indian J Pathol Microbiol ; 64(2): 382-384, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33851641

RESUMO

Rhabdomyolysis is a potentially life-threatening clinical syndrome characterized by the breakdown of skeletal muscle cells and release of creatine kinase (CK), lactate dehydrogenase (LDH), and myoglobin into the plasma and interstitial space. Rhabdomyolysis can occur due to a variety of causes and acute kidney injury (AKI) is one of its most dreaded complications occurring in 33%-50% patients. The main pathophysiology of renal injury is due to vasoconstriction, intraluminal casts, tubular obstruction, and direct myoglobin toxicity. As the symptoms are nonspecific, a high level of suspicion is required in the mind of the treating physician. Early diagnosis and prompt management with fluid resuscitation, initiation of renal replacement therapy (RRT), and elimination of causative agents can help prevent complications. We hereby report four interesting cases of this clinical syndrome with emphasis on the causative agents.


Assuntos
Injúria Renal Aguda/patologia , Mioglobina/sangue , Rabdomiólise/diagnóstico , Rabdomiólise/patologia , Injúria Renal Aguda/terapia , Adulto , Creatina Quinase/sangue , Feminino , Humanos , Rim/patologia , L-Lactato Desidrogenase/sangue , Masculino , Pessoa de Meia-Idade , Músculo Estriado/patologia , Terapia de Substituição Renal/métodos , Rabdomiólise/terapia , Adulto Jovem
2.
Saudi J Kidney Dis Transpl ; 31(3): 676-680, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32655053

RESUMO

Classical Alport syndrome is a rare X-linked disease of males (85%) presenting early with hematuria, ocular, and hearing defects. Proteinuria and renal failure are less common in the early stages. Here, we report the case of a young female with nephrotic range proteinuria, microscopic hematuria, and renal failure. A keen observation of abundant interstitial foam cells with suspicious glomerular basement membrane changes on kidney biopsy hinted the possibility of Alport syndrome. Further directed testing of the index patient and her family members including genetic analysis revealed a rare pathogenic variant of COL4A homozygous autosomal recessive Alport syndrome. Pedigree analysis showed that the peculiar inheritance could be due to maternal gonadal mosaicism or uniparental isodisomy of paternal genes alone.


Assuntos
Nefrite Hereditária , Síndrome Nefrótica , Adulto , Colágeno Tipo IV/genética , Feminino , Membrana Basal Glomerular/patologia , Hematúria/etiologia , Humanos , Rim/patologia , Nefrite Hereditária/complicações , Nefrite Hereditária/diagnóstico , Nefrite Hereditária/patologia , Síndrome Nefrótica/diagnóstico , Síndrome Nefrótica/etiologia , Síndrome Nefrótica/patologia , Linhagem
3.
Saudi J Kidney Dis Transpl ; 31(6): 1320-1330, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33565444

RESUMO

In this study, we aimed to measure glomerular filtration rate (mGFR) using 99Tc DTPA in patients with Child-Pugh C cirrhosis and normal serum creatinine levels; and to compare the performance of creatinine and cystatin C-based equations [estimated GFRs (eGFRs)] to 99TcDTPA GFR in the same group. We selected a group of 65 consecutive patients with advanced liver cirrhosis and apparently normal renal function by serum creatinine alone. Patients with confounding and reversible factors were excluded. Demographic data, blood, urine, and imaging tests along with simultaneous measurement of serum creatinine and cystatin C were analyzed. The GFR was measured by 99Tc DTPAscintigraphy (mGFR) in 41 patients. We compared the performance of chronic kidney disease epidemiology collaboration (CKD-EPI-creatinine, CKD-EPI-cystatinC, CKD-EPI-creatinine-cystatinC) and Modification of Diet in Renal Disease equation equations for bias (mean difference), precision (root mean square error), and accuracy (P10 and P30). Bland-Altman plots were used to show the agreement of eGFR and mGFR. Twenty-five out of 41 patients (61%) had significant renal dysfunction (GFR ≤60 mL/min/ 1.73m2) by 99TcDTPA in our study and three patients were already in Stage 4 CKD. Unlike serum creatinine, serum cystatin C values were deranged in these patients. Among all GFR estimating formulae, CKD-EPI-creatinine-cystatinC combined equation had the least bias (-2.3), superior precision (7.1), highest P30 accuracy (78%), good sensitivity (87.5%), and best specificity (96%) in our study. Two-thirds of patients with cirrhosis had significant renal impairment despite having normal serum creatinine. Isolated serum creatinine values are misleading in cirrhosis. Cystatin C unmasks renal dysfunction in these patients. CKD-EPI-creatinine-cystatinC equation showed the best correlation and accuracy with 99TcDTPA GFR in our study. Creatinine based GFR estimation is fallacious in cirrhosis. Cystatin C and equations based on it may be worthwhile in liver disease.


Assuntos
Creatinina/sangue , Cistatina C/sangue , Cirrose Hepática/fisiopatologia , Insuficiência Renal/diagnóstico , Insuficiência Renal/fisiopatologia , Adulto , Estudos Transversais , Feminino , Taxa de Filtração Glomerular , Humanos , Cirrose Hepática/sangue , Cirrose Hepática/complicações , Masculino , Conceitos Matemáticos , Pessoa de Meia-Idade , Cintilografia , Insuficiência Renal/sangue , Insuficiência Renal/complicações , Sensibilidade e Especificidade , Pentetato de Tecnécio Tc 99m
4.
Virusdisease ; 30(4): 490-497, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31897414

RESUMO

The availability of generic direct acting antivirals (DAAs) for hepatitis C virus (HCV) treatment has prompted many low-and-middle-income countries to launch HCV elimination programs. Because the efficacy of some of these generic DAAs varies by HCV viral subtype, information on subtype distribution can contribute important information to these elimination programs. We conducted a cross-sectional serosurvey to characterize HCV subtype diversity among HIV positive people who inject drugs (PWID) across 14 cities in India. Of 801 HIV positive PWID sampled, 639 tested HCV antibody positive (78.9%). Among 105 samples sequenced, genotype 3 (58.1%) was the most commonly observed followed by genotype 1 (36.2%) and genotype 6 (5.7%). Of the genotype 3 infections, 65% were subtype 3a and 35% were subtype 3b. Of the genotype 1 infections, 94% were subtype 1a and 6% were subtype 1b. All genotype 6 samples were subtype 6n. There was some variability in genotype diversity depending on geographic region and PWID epidemic stage with greater diversity observed in older PWID epidemics. One sequence, HY018, did not cluster with any known reference sequences in phylogenetic analysis. Nearly 80% of HIV infected PWID across India are co-infected with HCV, and subtype prevalence and genetic diversity varied by region and PWID epidemic stage. HCV elimination programs in India will need to consider HCV subtype.

5.
Int J Drug Policy ; 57: 111-118, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29730586

RESUMO

BACKGROUND: In some regions, HIV incidence is rising among people who inject drugs (PWID). Combination prevention approaches are well suited to PWID who face multiple sources of HIV risk. This analysis investigates patterns of utilisation to basic HIV services (HIV counselling and testing [HCT], antiretroviral therapy [ART]) as well as harm reduction programs (needle and syringe exchange programs [NSEP] and opioid agonist therapy [OAT]) among PWID and how utilisation of harm reduction services is associated with HIV-related care seeking behaviours. METHODS: Respondent-driven sampling was used to recruit 14,481 PWID across 15 cities in India. Sampling-weighted multilevel logistic regression models assessed associations between utilisation of harm reduction service and HCT and ART use among those indicated (90.3% and 5.0% of full sample, respectively). We considered both recent (prior year) and ever use of services. RESULTS: Overall, 42.3% reported prior HIV testing and 57.9% of eligible persons reported ART initiation, but overlap with NSEP and OAT use was limited. In adjusted models, recent and ever use of both NSEP and OAT were significantly associated with recent and ever HCT utilisation, respectively; however, harm reduction utilisation was not associated with ART initiation among eligible participants. CONCLUSIONS: Harm reduction services may play a key role in linking PWID with HIV testing; however, they were not associated with ART initiation among eligible individuals. Moreover, a large majority who utilised NSEP and OAT were not engaged in optimal HIV care or prevention, highlighting missed opportunities and a need for stronger linkages between NSEP/OAT and HIV care and treatment, particularly among those actively injecting. These findings provide key insights to better understand how services can be linked or combined to optimise service utilisation among PWID.


Assuntos
Infecções por HIV/prevenção & controle , Redução do Dano , Aceitação pelo Paciente de Cuidados de Saúde , Abuso de Substâncias por Via Intravenosa/psicologia , Adulto , Feminino , Infecções por HIV/complicações , Humanos , Masculino , Abuso de Substâncias por Via Intravenosa/complicações , Adulto Jovem
6.
Acta Paediatr ; 107(10): 1722-1725, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29617052

RESUMO

AIM: Urinary N-terminal B-type natriuretic peptide NTproBNP levels are associated with the development of retinopathy of prematurity (ROP) in infants <30 weeks of gestation. The incidence of ROP in more mature infants who meet other ROP screening criteria is very low. We therefore aimed to test whether urinary NTproBNP predicted ROP development in these infants. METHODS: Prospective observational study in 151 UK infants ≥30 + 0 weeks of gestation but also <32 weeks of gestation and/or <1501 g, to test the hypothesis that urinary NTproBNP levels on day of life (DOL) 14 and 28 were able to predict ROP development. RESULTS: Urinary NTproBNP concentrations on day 14 and day 28 of life did not differ between infants with and without ROP (medians 144 vs 128 mcg/mL, respectively, p = 0.86 on DOL 14 and medians 117 vs 94 mcg/mL, respectively, p = 0.64 on DOL28). CONCLUSION: The association previously shown for infants <30 completed weeks between urinary NTproBNP and the development of ROP was not seen in more mature infants. Urinary NTproBNP does not appear helpful in rationalising direct ophthalmoscopic screening for ROP in more mature infants, and may suggest a difference in pathophysiology of ROP in this population.


Assuntos
Peptídeo Natriurético Encefálico/urina , Fragmentos de Peptídeos/urina , Retinopatia da Prematuridade/diagnóstico , Biomarcadores/urina , Feminino , Humanos , Recém-Nascido , Recém-Nascido Prematuro , Masculino , Estudos Prospectivos , Retinopatia da Prematuridade/urina
7.
Artigo em Inglês | MEDLINE | ID: mdl-29202126

RESUMO

Mobile phones remain a largely untapped resource in the ongoing challenge to address Female Sex Worker (FSW) health, including HIV prevention services, in India. An important step towards designing effective mobile phone-based initiatives for FSWs is clarifying the contextual influences of mobile phone solicitation on sexual risk behavior. In this paper, we extend previously identified associations between mobile phone solicitation and condom practices by examining whether this association is moderated by sex work pay and offer key considerations for future research and implementation. Specifically, we conducted an analysis among 589 Indian FSWs, where FSWs who did not use mobile phones to solicit clients had the lowest mean sex work pay (INR 394/ USD 6.54) compared to FSWs who used both mobile and traditional strategies (INR 563/ USD 9.34). Our analysis indicate low paid FSWs who used mobile phones concurrently with traditional strategies had 2.46 times higher odds of inconsistent condom use compared to low paid FSWs who did not use mobile phones for client solicitation. No such effect was identified among high paid FSWs. These findings also identified group level differences among FSWs reporting different mobile phone solicitation strategies, including violence, client condom use and HIV status. Our results indicate that low pay does moderate the association between mobile phone solicitation and condom practices, but only among a sub-set of low paid FSWs. These findings also demonstrate the utility of classification by different mobile phone solicitation strategies for accurate assessment of sexual risk among mobile phone soliciting FSWs. In turn, this paves the way for novel approaches to utilize mobile phones for FSW HIV prevention. We discuss one such example, a mobile phone-based rapid screening tool for acute HIV infection targeting Indian FSWs.

8.
Semin Fetal Neonatal Med ; 17(5): 295-300, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22840681

RESUMO

Recent advancements in fetal imaging and antenatal care have enabled identification of numerous anomalies including agenesis of corpus callosum and posterior fossa abnormalities. One of the important determinants of long-term prognosis in these conditions is the presence of central nervous system (CNS) and extra-CNS anomalies. The difficulty in confirming the isolated nature of these conditions antenatally and the lack of clear information regarding long-term prognoses makes it difficult for the clinician to provide accurate information to the parents antenatally. Caring for these families would require input from a multidisciplinary team involving obstetricians, geneticists, neurologists, radiologists and neonatologists.


Assuntos
Agenesia do Corpo Caloso/embriologia , Cerebelo/anormalidades , Cerebelo/embriologia , Ultrassonografia Pré-Natal/métodos , Agenesia do Corpo Caloso/diagnóstico por imagem , Cerebelo/diagnóstico por imagem , Feminino , Feto , Humanos , Lactente , Gravidez
9.
Int J Drug Policy ; 23(6): 498-504, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22608567

RESUMO

BACKGROUND: HIV transmission in India is primarily heterosexual and there is a concentrated HIV epidemic among female sex workers (FSWs). Earlier reports demonstrate that many FSWs consume alcohol regularly before sexual encounters. This qualitative study is part of a larger quantitative study designed to assess alcohol consumption patterns among female sex workers and their association with sexual risk taking. Here we investigate the environmental influence, reasons for and consequences of consuming alcohol in the FSW population. METHODS: Trained staff from two Non-Governmental Organizations in Andhra Pradesh and Kerala conducted semi-structured interviews with 63 FSWs in Chirala, Andhra Pradesh (n = 35) and Calicut, Kerala (n = 28) following extensive formative research, including social mapping and key informant interviews, to assess drinking patterns and sexual risk behaviors. RESULTS: FSWs reported consuming alcohol in multiple contexts: sexual, social, mental health and self-medication. Alcohol consumption during sexual encounters with clients was usually forced, but some women drank voluntarily. Social drinking took place in public locations such as bars and in private locations including deserted buildings, roads and inside autorickshaws (motorcycle taxis). Consequences of alcohol consumption included failure to use condoms and to collect payments from clients, violence, legal problems, gastrointestinal side effects, economic loss and interference with family responsibilities. CONCLUSION: FSWs consume alcohol in multilevel contexts. Alcohol consumption during transactional sex is often forced and can lead to failure to use condoms. Social drinkers consume alcohol with other trusted FSWs for entertainment and to help cope with psychosocial stressors. There are multiple reasons for and consequences of alcohol consumption in this population and future interventions should target each specific aspect of alcohol use.


Assuntos
Consumo de Bebidas Alcoólicas/epidemiologia , Infecções por HIV/epidemiologia , Comportamentos Relacionados com a Saúde , Conhecimentos, Atitudes e Prática em Saúde , Trabalho Sexual/estatística & dados numéricos , Profissionais do Sexo/estatística & dados numéricos , Sexo sem Proteção/estatística & dados numéricos , Saúde da Mulher/estatística & dados numéricos , Adaptação Psicológica , Adulto , Consumo de Bebidas Alcoólicas/psicologia , Feminino , Infecções por HIV/prevenção & controle , Infecções por HIV/transmissão , Humanos , Índia/epidemiologia , Pessoa de Meia-Idade , Pesquisa Qualitativa , Automedicação/estatística & dados numéricos , Trabalho Sexual/psicologia , Profissionais do Sexo/psicologia , Comportamento Social , Fatores Socioeconômicos , Confiança , Sexo sem Proteção/prevenção & controle , Sexo sem Proteção/psicologia , Volição , Adulto Jovem
10.
Gen Dent ; 59(4): e153-5, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21903554

RESUMO

Radicular cysts are commonly found odontogenic cysts in the jaws. The lesion is diagnosed mainly in young patients during the second decade of life. In the majority of cases, it is asymptomatic. This paper reports a rare case in which traumatic occlusion was identified as the etiology of a radicular cyst. Endodontic treatment was performed and the traumatic occlusion also was corrected. A six-month follow-up appointment found good healing of the periapical region.


Assuntos
Oclusão Dentária Traumática/complicações , Doenças Maxilares/etiologia , Cisto Radicular/etiologia , Dente Canino/patologia , Oclusão Dentária Traumática/terapia , Feminino , Seguimentos , Humanos , Incisivo/patologia , Cisto Radicular/terapia , Tratamento do Canal Radicular , Dente não Vital/etiologia , Adulto Jovem
11.
AIDS Behav ; 14 Suppl 1: S136-46, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20544382

RESUMO

This qualitative study examines the role of alcohol in sexual risk among male migrant workers and female sex workers in two South Indian states. Most men reported using alcohol for increased energy and courage prior to their sexual experiences and to reduce feelings of loneliness and isolation. Sex workers, on the other hand, often stated that they avoided alcohol prior to sex in order to stay alert and reduce the risk of violence. Both groups reported that drinking often increased male aggression and reduced condom use. Research is needed to examine the prevalence of these patterns as well as factors associated with sexual risk and violence, in order to develop targeted interventions for these groups. Future risk reduction programs may benefit from addressing safer ways of meeting the needs expressed by the participants. This may include strategies to defuse volatile situations, safe ways of improving the sexual experience, and interventions aimed at alleviating loneliness and isolation for migrants.


Assuntos
Consumo de Bebidas Alcoólicas/epidemiologia , Infecções por HIV/epidemiologia , Assunção de Riscos , Trabalho Sexual/estatística & dados numéricos , Comportamento Sexual , Migrantes/estatística & dados numéricos , Preservativos/estatística & dados numéricos , Feminino , Infecções por HIV/prevenção & controle , Humanos , Índia/epidemiologia , Entrevistas como Assunto , Masculino
12.
Subst Use Misuse ; 45(3): 354-67, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20141452

RESUMO

We characterize the demographics, injection practices and risk behaviours of 1,158 injection drug users (IDUs) in Chennai, the capital of Tamil Nadu in southern India, who were recruited during 2005-2006 by community outreach. The median age was 35 years; the majority of IDUs were male, of Tamil ethnicity and married, and earning less than US$75 per month. Most (76%) had injected in the prior month. The median age at first injection was 25 years; the most common drug injected was heroin (80%) followed by buprenorphine. High risk behaviours were common and included needle-sharing, unsafe disposal, and inappropriate cleaning of needles as well as limited condom use. IDUs in India need to be educated on harm reduction and safe-injection practices; Pharmacies could serve as potential venues for HIV prevention interventions among IDUs in India, as most IDUs obtain their needles from pharmacies without prescription.


Assuntos
Usuários de Drogas/psicologia , Abuso de Substâncias por Via Intravenosa/psicologia , Adulto , Fatores Etários , Estudos de Coortes , Demografia , Usuários de Drogas/estatística & dados numéricos , Feminino , Humanos , Índia , Masculino , Assunção de Riscos , Fatores Socioeconômicos , Sexo sem Proteção/estatística & dados numéricos
14.
Violence Against Women ; 15(7): 753-73, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19448166

RESUMO

This article examined the prevalence of physical and sexual violence among 1,974 married women from 40 low-income communities in Chennai, India. The authors found a 99% and 75% lifetime prevalence of physical abuse and forced sex, respectively, whereas 65% of women experienced more than five episodes of physical abuse in the 3 months preceding the survey. Factors associated with violence after multivariate adjustment included elementary/middle school education and variables suggesting economic insecurity. These domestic violence rates exceed those in prior Indian reports, suggesting women in slums may be at increased risk for HIV and other sexually transmitted infections.


Assuntos
Mulheres Maltratadas/estatística & dados numéricos , Infecções por HIV/epidemiologia , Áreas de Pobreza , Estupro/estatística & dados numéricos , Maus-Tratos Conjugais/estatística & dados numéricos , População Urbana/estatística & dados numéricos , Adulto , Feminino , Infecções por HIV/prevenção & controle , Humanos , Índia/epidemiologia , Estilo de Vida , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Pobreza/estatística & dados numéricos , Prevalência , Estupro/psicologia , Fatores de Risco , Fatores Socioeconômicos , Cônjuges/estatística & dados numéricos
15.
Endocrinology ; 141(6): 2200-8, 2000 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-10830309

RESUMO

We show here that A10 cells express the phospholipase D (PLD) isoforms PLD1b and PLD2. The activation of PLD in these cells by angiotensin II (AngII), endothelin-1 (ET-1), and platelet-derived growth factor (PDGF) was found to be sensitive to inhibitors of the activation of ADP-ribosylation factor (ARF) but not to blockers of Rho protein function. PDGF, AngII, and ET-1 induced the binding of ARF proteins to cell membranes in a permeabilized cell assay. Cells permeabilized and depleted of ARF were no longer sensitive to stimulation with AngII, ET-1, or PDGF, but the addition of recombinant myristoylated human ARF1 restored agonist-dependent PLD activity. Expression of dominant negative ARF mutants blocked receptor-dependent activation of PLD. PLD activity was also potently stimulated by treatment with phorbol esters, but this activity was only partially inhibited by brefeldin A or by the overexpression of ARF dominant negative mutants. Transient expression of catalytically inactive mutants of PLD2, but not PLD1, inhibited significantly PDGF- and AngII-dependent PLD activity. We conclude: 1) the activation of PLD by cell surface receptors occurs primarily by an ARF-dependent mechanism in A10 cells, whereas the activation of PLD by protein kinase C-dependent pathways is only partially dependent on the regulation of ARF proteins; and 2) cell surface receptors, such as AngII and PDGF, signal primarily via PLD2 in A10 cells.


Assuntos
ADP Ribose Transferases/farmacologia , Fatores de Ribosilação do ADP/fisiologia , Angiotensina II/farmacologia , Toxinas Botulínicas , Endotelina-1/farmacologia , Proteínas Monoméricas de Ligação ao GTP/fisiologia , Músculo Liso Vascular/enzimologia , Fosfolipase D/metabolismo , Fator de Crescimento Derivado de Plaquetas/farmacologia , Fatores de Ribosilação do ADP/genética , Brefeldina A/farmacologia , Linhagem Celular , Clostridium botulinum/enzimologia , Ativação Enzimática/efeitos dos fármacos , Expressão Gênica , Proteínas de Fluorescência Verde , Humanos , Proteínas Luminescentes/genética , Mutação , Proteínas Recombinantes de Fusão/metabolismo , Transfecção
16.
J Biol Chem ; 274(29): 20545-9, 1999 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-10400684

RESUMO

ADP-ribosylation factor 1 (ARF1) is a key regulator of transport in the secretory system. Like all small GTPases, deactivation of ARF1 requires a GTPase-activating protein (GAP) that promotes hydrolysis of GTP to GDP on ARF1. Structure-function analysis of a GAP for ARF1 revealed that its activity in vivo requires not only a domain that catalyzes hydrolysis of GTP on ARF1 but also a non-catalytic domain. In this study, we show that the non-catalytic domain of GAP is required for its recruitment from cytosol to membranes and that this domain mediates the interaction of GAP with the transmembrane KDEL receptor. Blocking its interaction with the KDEL receptor leaves the GAP cytosolic and prevents the deactivation in vivo of Golgi-localized ARF1. Thus, these findings suggest that the KDEL receptor plays a critical role in the function of GAP by regulating its recruitment from cytosol to membranes, where it can then act on its membrane-restricted target, the GTP-bound form of ARF1.


Assuntos
Proteínas de Ligação ao GTP/metabolismo , Proteínas/metabolismo , Receptores de Peptídeos/metabolismo , Fator 1 de Ribosilação do ADP , Fatores de Ribosilação do ADP , Animais , Células COS , Domínio Catalítico , Proteínas Ativadoras de GTPase , Células HeLa , Humanos , Cinética , Mutação , Ligação Proteica , Receptores de Peptídeos/genética
17.
J Biol Chem ; 274(2): 1131-9, 1999 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-9873061

RESUMO

The primary known function of phospholipase D (PLD) is to generate phosphatidic acid (PA) via the hydrolysis of phosphatidylcholine. However, the functional role of PA is not well understood. We report here evidence that links the activation of PLD by insulin and the subsequent generation of PA to the activation of the Raf-1-mitogen-activated protein kinase (MAPK) cascade. Brefeldin A (BFA), an inhibitor of the activation of ADP-ribosylation factor proteins, inhibited insulin-dependent production of PA and MAPK phosphorylation. The addition of PA reversed the inhibition of MAPK activation by BFA. Overexpression of a catalytically inactive variant of PLD2, but not PLD1, blocked insulin-dependent activation of PLD and phosphorylation of MAPK. Real time imaging analysis showed that insulin induced Raf-1 translocation to cell membranes by a process that was inhibited by BFA. PA addition reversed the effects of BFA on Raf-1 translocation. However, PA did not activate Raf-1 in vitro or in vivo, suggesting that the primary function of PA is to enhance the recruitment of Raf-1 to the plasma membrane where other factors may activate it. Finally, we found that the recruitment of Raf-1 to the plasma membrane was transient, but Raf-1 remained bound to endocytic vesicles.


Assuntos
Proteínas Quinases Dependentes de Cálcio-Calmodulina/metabolismo , Ácidos Fosfatídicos/metabolismo , Fosfolipase D/metabolismo , Proteínas Proto-Oncogênicas c-raf/metabolismo , Animais , Transporte Biológico , Linhagem Celular Transformada , Membrana Celular/enzimologia , Membrana Celular/metabolismo , Ativação Enzimática , Ratos
18.
J Cell Sci ; 111 ( Pt 9): 1277-85, 1998 May.
Artigo em Inglês | MEDLINE | ID: mdl-9547306

RESUMO

ADP-ribosylation factors (ARF) are small G proteins that play key roles in vesicular transport processes. We have studied the distribution of ARF1 in live cells using chimeras of ARF1 mutants (wild type (wt) ARF1; Q71L-ARF1 (reduced GTPase); T31N (low affinity for GTP); and (Delta)Nwt (deletion of amino acids 2-18)) with green fluorescent protein (GFP). Confocal microscopy studies showed that the wt and Q71L proteins were localized in the Golgi and cytoplasm. The (Delta)Nwt and the T31N mutants were exclusively cytoplasmic. The behavior of the wt and Q71L proteins was studied in detail. About 15% of wt-ARF1-GFP was bound to the Golgi. Bound wt-ARF1-GFP dissociated rapidly after addition of Brefeldin A (BFA). This process did not appear to be a consequence of BFA-induced disappearance of the Golgi. Photobleaching recovery showed that essentially all the ARF-GFP was mobile, although it diffused very slowly. In contrast, about 40-50% of the Q71L mutant was found in the Golgi, and its rate of dissociation in the presence of BFA was slow and biphasic. Q71L-ARF1-GFP diffused more slowly than the wt. We conclude that ARF1 proteins exist in a dynamic equilibrium between Golgi-bound and cytosolic pools, and that the translocation of ARF in live cells requires the hydrolysis of GTP by the Golgi-bound protein.


Assuntos
Citosol/química , GTP Fosfo-Hidrolases/metabolismo , Proteínas de Ligação ao GTP/metabolismo , Guanosina Trifosfato/metabolismo , Fator 1 de Ribosilação do ADP , Fatores de Ribosilação do ADP , Animais , Antibacterianos/farmacologia , Transporte Biológico , Brefeldina A , Ciclopentanos/farmacologia , Fibroblastos/química , Fibroblastos/ultraestrutura , Fluorometria , GTP Fosfo-Hidrolases/análise , Proteínas de Ligação ao GTP/análise , Proteínas de Ligação ao GTP/química , Complexo de Golgi/química , Complexo de Golgi/efeitos dos fármacos , Proteínas de Fluorescência Verde , Humanos , Proteínas Luminescentes/análise , Macrolídeos , Fotoquímica , Ratos , Proteínas Recombinantes de Fusão/análise , Relação Estrutura-Atividade
19.
Virology ; 233(2): 392-401, 1997 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-9217062

RESUMO

Middle T (mT), the oncogene of murine polyomavirus, causes transformation of rat fibroblasts by activating a number of signal transducing pathways usually used by polypeptide growth factors and their receptors. Here, we report data regarding the activation of signal transducing pathways involving phospholipase D (PL-D). The hydrolysis of phospholipids by PL-D produces phosphatidic acid (PA), a compound with multiple biological effects. The PA content of cells expressing wild-type mT, introduced via a number of different methods, is approximately 50% higher than their untransformed counterparts. This increase in cellular PA content is associated with an approximately 65% increase in PL-D activity in cells expressing wild-type mT. We have also examined the effects of a number of site-directed mutants of mT, on both cellular PA levels and on PL-D activity. Mutants that do not produce mT (Py808A) or that produce a truncated, nonmembrane bound mT (Py1387T) have PA levels similar to that of control cells. Cells expressing the 322YF mutant of mT (which abolishes interaction of mT with phospholipase C gamma1) show increases in both PA levels and PL-D activity that are similar to those seen with wild-type mT. Expression of mutants that abolish the interaction of mT with either shc or with phosphatidylinositol 3-kinase (250YS and 315YF, respectively) cause an increase in PL-D activity comparable to that seen with wild-type mT. However, the PA content of cells expressing these mutants is not elevated. These results suggest that mT causes activation of cellular PL-D, but this activation alone is not sufficient to cause an increase in cellular PA content. Therefore, wild-type mT must affect another, as yet unknown, step in PA metabolism.


Assuntos
Antígenos Transformantes de Poliomavirus/metabolismo , Transformação Celular Viral , Fibroblastos/metabolismo , Ácidos Fosfatídicos/metabolismo , Fosfolipase D/metabolismo , Polyomavirus/fisiologia , Animais , Antígenos Transformantes de Poliomavirus/genética , Linhagem Celular , Diglicerídeos/metabolismo , Fibroblastos/citologia , Fibroblastos/virologia , Camundongos , Polyomavirus/genética , Ratos
20.
Curr Biol ; 7(6): 387-96, 1997 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-9197239

RESUMO

BACKGROUND: ADP-ribosylation factors (ARFs) have been shown to activate phospholipase D (PLD), an enzyme modulated by extracellular signals, including several growth factors and, in particular, insulin. We have tested the hypothesis that ARF proteins are involved specifically in insulin-induced activation of PLD. RESULTS: We found that in membranes obtained from HIRcB cells, a cell line derived from Rat-1 fibroblasts that overexpresses normal human insulin receptors, binding of the GTP analogue GTPgammaS to purified bovine or recombinant ARF was enhanced in the presence of insulin. Membranes obtained from cells that overexpressed a mutated, nonfunctional insulin receptor failed to stimulate ARF activation. Insulin promoted the association of ARF proteins with membranes in the presence of GTPgammaS in permeabilized cells. Insulin activated PLD in permeabilized HIRcB cells by a process that required GTPgammaS and ARF. Azido-gamma[32P]-GTP labelling of immunoprecipitated receptors revealed the presence of a unique 19 kD band; ARF proteins are approximately this size, and analysis using specific monoclonal antibodies demonstrated that ARF proteins coimmunoprecipitated with the insulin receptor. Coimmunoprecipitation of ARF with the receptor was inhibited by guanine nucleotides and stimulated by insulin. No evidence of the coprecipitation of ARF with mutant receptors could be obtained using azido-gamma[32P]-GTP or anti-ARF antibodies. CONCLUSIONS: The activation of ARF proteins is stimulated by insulin and this process plays an important role in insulin-mediated regulation of PLD.


Assuntos
Proteínas de Ligação ao GTP/metabolismo , Insulina/farmacologia , Fosfolipase D/metabolismo , Receptor de Insulina/metabolismo , Fatores de Ribosilação do ADP , Animais , Membrana Celular/metabolismo , Ativação Enzimática , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Humanos , Modelos Biológicos , Ligação Proteica , Ratos , Transdução de Sinais
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