RESUMO
BACKGROUND: Photo-numeric scales could lack precision and objectivity on evaluating the improvements on wrinkles after a treatment with botulinum toxin type A. The authors suggest a new digital evaluation method to analyze its effectiveness. OBJECTIVES: This study aims to investigate retrospectively the effect of intramuscular injection of botulinum toxin type A on skin texture in the lateral peri-orbital region with a new objective method. METHODS: Skin texture roughness (STR) in the lateral peri-orbital region is evaluated with a multi-directional light beam by light emitting diodes of different wavelengths (Antera 3D® ), before and after injections of 12 units of botulinum toxin type A. The wrinkles and lines deeper than 0.5 mm are filtered to measure accurately skin texture. RESULTS: We observed an improvement of STR in all cases treated with botulinum toxin type A. A significant decrease of STR was recorded as follows: 17.08% (P < .0001) at 4 weeks and 12.14% at 4 months (P = .001). CONCLUSION: Botulinum toxin type A treatment of crow's feet was able to improve STR. The Antera® device and software are a valuable, objective, easy and reproducible method to assess the effects of the toxin.
Assuntos
Inibidores da Liberação da Acetilcolina/administração & dosagem , Toxinas Botulínicas Tipo A/administração & dosagem , Envelhecimento da Pele/efeitos dos fármacos , Pele/anatomia & histologia , Inibidores da Liberação da Acetilcolina/farmacologia , Adulto , Idoso , Toxinas Botulínicas Tipo A/farmacologia , Preenchedores Dérmicos/administração & dosagem , Preenchedores Dérmicos/farmacologia , Feminino , Humanos , Injeções Intramusculares , Pessoa de Meia-Idade , Estudos Retrospectivos , Pele/efeitos dos fármacos , Envelhecimento da Pele/fisiologia , Software , Resultado do TratamentoRESUMO
UNLABELLED: We present the results of 26 patients with 31 consecutive displaced or unstable extra-articular fractures of the base and shaft of the proximal and middle phalanges of the digits of the hand, treated over a period of 12 months with an intramedullary headless compression screw and early mobilization with no splinting. All fractures healed with no major complications. Only one patient, who had a pathological fracture through an enchondroma, required a tenolysis to improve the mobility of the finger. This technique seems to be technically simple, effective and with few drawbacks. LEVEL OF EVIDENCE: IV.
Assuntos
Parafusos Ósseos , Falanges dos Dedos da Mão/lesões , Fixação Intramedular de Fraturas/instrumentação , Fraturas Ósseas/cirurgia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Deambulação Precoce , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Adulto JovemRESUMO
Digital replantation is a well-established and increasingly common procedure in specialized hand surgery units worldwide. Replantation after complex trauma is often challenging due to severely injured, small-diameter vessels, especially at the distal level. Digit salvage by arteriovenous anastomosis has been inadequately described in the literature for such cases. The objective of this study was to evaluate the outcomes and complications of arteriovenous digital replantation in complex amputations. We reviewed five cases of digital replantation using a single palmar afferent arteriovenous anastomosis and drainage via a dorsal vein. The postoperative protocol followed our standard replantation protocol. All digits survived with no revision procedures. No major complications were observed. One digit developed partial epidermolysis and one thumb developed marginal skin necrosis, both treated conservatively. The color of the replanted digits was not a reliable monitoring parameter but capillary refill was consistently visible. Microangiography performed four months after surgery demonstrated good digit perfusion. Our results support palmar arteriovenous anastomosis as a reliable alternative in digital replantation if distal arteries are unavailable for anastomosis. The results also suggest that this digit salvage procedure can be carried out at a more proximal level than previously reported.
Assuntos
Amputação Traumática/cirurgia , Anastomose Arteriovenosa , Traumatismos dos Dedos/cirurgia , Reimplante/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Humanos , Pessoa de Meia-IdadeRESUMO
PURPOSE: The aim of the study is to improve operative speed and precision of haemangiomas excision. CASE-REPORT: haemangioma is a common affection of the 8% of the population during the neonatal period. In complicated cases and involution sequelae surgical treatment is the first choice. The Authors propose a surgical refinement to prevent intraoperative bleeding. METHODS: several suture stitches were placed around the hemangioma. The edges of the lesion became more defined, thus allowing accurate excision. RESULTS AND CONCLUSIONS: Haemangiomas are characterized by rich blood supply. Surgery is often hindered by massive bleeding and Temporary placement of full-thickness sutures, surrounding the hemangioma, allowed a noticeable improvement in hemostasis precision and greater definition of the margins of the hemangioma.
Assuntos
Hemangioma/cirurgia , Hemostasia Cirúrgica , Neoplasias Cutâneas/cirurgia , Blefaroptose/etiologia , Criança , Pálpebras/patologia , Feminino , Hemangioma/complicações , Hemangioma/patologia , Hemorragia/etiologia , Hemorragia/cirurgia , Hemostasia Cirúrgica/métodos , Humanos , Imageamento por Ressonância Magnética/métodos , Procedimentos de Cirurgia Plástica , Medição de Risco , Índice de Gravidade de Doença , Neoplasias Cutâneas/complicações , Neoplasias Cutâneas/patologia , Técnicas de Sutura , Fatores de Tempo , Resultado do TratamentoRESUMO
This is an observational case series of 15 patients with full-thickness traumatic wound defects treated with a dermal substitute. There were 8 male and 7 female patients with a mean age of 36.6 years. Eight patients had trauma to the lower limbs and 7 were of the upper limbs, with the average lesion size 104.4 cm(2) (range 6-490 cm(2)). The time to complete healing had a mean average time of 26.8 days (range 16-60 days). All patients went on to successful repair with 6 patients requiring a second application of the substitute and 5 patients needing split thickness skin grafts. Infection was recorded in one patient.
RESUMO
Lower limb reconstruction with pedicled or free flaps can be commonly compromised by venous insufficiency. This complication often leads to partial/complete flap necrosis and increases the risk of superinfection. Negative-pressure wound therapy (NPWT) is known to increase local blood flow, decrease edema, promote tissue granulation, and reduce the likelihood of soft tissue infection. This study aims to evaluate the effectiveness of NPWT in the treatment of congested pedicled and free flaps of the lower limb after reconstructions in lower limb traumas. A retrospective analysis was performed on four congested (pedicled and free) flaps on the lower limbs. NPWT was applied in all cases after partial flap debridement. NPWT was able to improve and resolve tissue edema and venous insufficiency, avoid further flap necrosis, and promote granulation. On NPWT removal, a split-thickness skin graft was applied on the wound, achieving complete and uneventful healing. NPWT is a useful instrument in managing flaps affected by venous insufficiency in lower limb reconstruction, although larger studies are necessary to better define the effectiveness and indications of NPWT in this setting.
Assuntos
Retalhos de Tecido Biológico/irrigação sanguínea , Hiperemia/terapia , Traumatismos da Perna/cirurgia , Tratamento de Ferimentos com Pressão Negativa/métodos , Complicações Pós-Operatórias/terapia , Retalhos Cirúrgicos/irrigação sanguínea , Adulto , Desbridamento , Edema/patologia , Edema/cirurgia , Edema/terapia , Feminino , Tecido de Granulação/patologia , Humanos , Hiperemia/patologia , Hiperemia/cirurgia , Traumatismos da Perna/patologia , Masculino , Complicações Pós-Operatórias/patologia , Complicações Pós-Operatórias/cirurgia , Procedimentos de Cirurgia Plástica , Estudos Retrospectivos , CicatrizaçãoRESUMO
The purpose of this study was to evaluate the effectiveness and middle-term durability of the results achieved with perineural fat grafting of painful neuromas of the upper limb. We retrospectively analysed eight patients, affected by eight neuromas, treated by neuroma excision and fat grafting around the proximal nerve stump. Clinical parameters, the disabilities of the arm shoulder and hand score, and the visual analogue scale were recorded at 2, 6 and 12 months after surgery. A reduction of 23.2% was observed in the mean disabilities of the arm shoulder and hand scores at 12 months. The spontaneous baseline visual analogue scale score showed a mean improvement of 22% at 12 months, although not this was not statistically significant. Perineural fat grafting is a quick and useful procedure and could represent a useful primary operation in the treatment of pain syndromes of neuropatic origin.
Assuntos
Gordura Abdominal/transplante , Antebraço/inervação , Neuralgia/cirurgia , Neuroma/cirurgia , Neoplasias do Sistema Nervoso Periférico/cirurgia , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neuralgia/etiologia , Neuroma/complicações , Medição da Dor , Neoplasias do Sistema Nervoso Periférico/complicações , Projetos Piloto , Estudos Retrospectivos , Resultado do Tratamento , Adulto JovemRESUMO
Glutamate transport in early, undifferentiated oligodendrocytic precursors has not been characterized thus far. Here we show that human oligodendroglioma Hs683 cells are not endowed with EAAT-dependent anionic amino acid transport. However, in these cells, but not in U373 human glioblastoma cells, valproic acid (VPA), an inhibitor of histone deacetylases, markedly induces SLC1A1 mRNA, which encodes for the glutamate transporter EAAT3. The effect is detectable after 8h and persists up to 120h of treatment. EAAT3 protein increase becomes detectable after 24h of treatment and reaches its maximum after 72-96h, when it is eightfold more abundant than control. The initial influx of d-aspartate increases in parallel, exhibiting the typical features of an EAAT3-mediated process. SLC1A1 mRNA induction is associated with the increased expression of PDGFRA mRNA (+150%), a marker of early oligodendrocyte precursor cells, while the expression of GFAP, CNP and TUBB3 remains unchanged. Short term experiments have indicated that the VPA effect is shared by trichostatin A, another inhibitor of histone deacetylases. On the contrary, EAAT3 induction is neither prevented by inhibitors of mitogen-activated protein kinases nor triggered by a prolonged incubation with lithium, thus excluding a role for the GSK3ß/ß-catenin pathway. Thus, the VPA-dependent induction of the glutamate transporter EAAT3 in human oligodendroglioma cells likely occurs through an epigenetic mechanism and may represent an early indicator of commitment to oligodendrocytic differentiation.
Assuntos
Anticonvulsivantes/farmacologia , Transportador 3 de Aminoácido Excitatório/genética , Transportador 3 de Aminoácido Excitatório/metabolismo , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Ácido Valproico/farmacologia , 2',3'-Nucleotídeo Cíclico 3'-Fosfodiesterase/metabolismo , Ácido Aspártico/metabolismo , Ácido Aspártico/farmacologia , Linhagem Celular Tumoral , Inibidores Enzimáticos/farmacologia , Proteína Glial Fibrilar Ácida/metabolismo , Humanos , Oligodendroglioma/patologia , Dibutirato de 12,13-Forbol/farmacologia , Transporte Proteico/efeitos dos fármacos , RNA Mensageiro/metabolismo , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/genética , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Transdução de Sinais/efeitos dos fármacos , Fatores de Tempo , Trítio/metabolismo , Tubulina (Proteína)/metabolismoRESUMO
Giant congenital pigmented naevi is a great reconstructive challenge for the pediatric and plastic surgeons. Due to the increased risk of malignant transformation in such lesions, many procedures have been used to remove giant congenital naevi like dermoabrasion, laser treatment or surgical excision combined with reconstruction through skin expansion or skin grafting; among these, only a complete excision can offer an efficacious treatment. In our centre we use the "tissue expansion" technique in order to achieve a sufficient quantity of normal skin to perform a both staged and radical excision of these giant lesions.
Assuntos
Nevo Pigmentado/congênito , Neoplasias Cutâneas/congênito , Criança , Humanos , Nevo Pigmentado/patologia , Nevo Pigmentado/terapia , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/terapiaRESUMO
BACKGROUND: treatment of congenital ptoses and blepharophimoses relies on levator resections and frontalis suspensions. Several techniques of levator resection have been described in literature, some of them include tarsal resections and resections of the Müller muscle. Nevertheless a gold treatment have not been detected yet. Frontalis suspension is performed when levator muscle is not functional or when ptosis is severe. The suspension could be carried out with several materials: ePTFE, silicon rods, poly-propylene, nylon, braided poliester, but the preferable material is considered the autologous fascia lata. AIMS: this study was designate to determine retrospectively if the indications of surgery are correct, considering age, severity of pathology, relapses and complications. An analysis of demographic data and outcomes for each technique is performed. METHODS: in this study we analyze case series of 33 pediatric patients affected by congenital ptosis and blepharophimosis congenital syndrome, surgically treated from 2000 to 2008 in the ophtalmic pediatric surgery department at the Niguarda Hospital of Milan. A literature review was also performed. RESULTS: the mean age at presentation was 4.13. The diagnosis was precocious in most cases and often helped by some recognizable clinical signs: compensatory head posture (48.5%), anisometropia (36.4%), astigmatism (48.5%), strabismus (36.4%) and amblyopia (15.2%). Most of patients was treated with frontalis suspension (57.6%) and their age was significatively lower than patients treated with levator resection. No difference about complications and recurrence was reported between the two techniques. Complications and recurrence amount to 39.4%. CONCLUSION: these results are in line with other studies in literature. A precociuos treatment is able to reduce the incidence of amblyopia from 34% to 8%. The choice of the treatment (resection Vs suspension) has to consider the age of the patient, the severity of ptosis and avaibility of fascia lata. Nevertheless no significative difference in outcomes have been demonstrated between the two techniques.
Assuntos
Blefarofimose/cirurgia , Blefaroptose/congênito , Blefaroptose/cirurgia , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Procedimentos Cirúrgicos Oftalmológicos/métodos , Estudos RetrospectivosRESUMO
UNLABELLED: We have examined 11 patients with aplasia of the thumb and we have treated by pollicization of the index finger. We have conducted a follow up of 5 years. The total absence of the thumb may be an isolated anomaly, but it is often associated with some other congenital malformation. The absent thumb is as an autosomal dominant pathology or may be sporadic. It is frequently observed in the Holt-Oram syndrome, Fanconi's anemia, and ring D chromosome abnormalities. It is occasionally observed in the Rothmund syndrome, trisomy, thalidomide embryopathology and other congenital syndromes. An absent radius is almost always associated with an absent thumb, except in thrombocytopenia radial aplasia (Fanconi's syndrome), where the thumb is present even when the radius is absent. The treatment in most cases of the absent thumb is to perform a pollicization of the index finger. Our isolated congenital absence of the thumb patients have been treated with pollicization as described by Buck-Gramcko works well. It is a beautiful operation for the congenitally deformed, aplastic, or missing thumb. Pollicization of the index finger gives good functional and cosmetic results which are maintained. CONCLUSIONS: The total absence of the thumb in the congenitally pathology gives the hand of the patient insufficient in the functional movement and no cosmetic. So the pollicization with the second index fined gives a good reconstruction for the neo-thumb. In our five years follow-up, the 11 young patients that were treated with the pollicization, they are satisfy and use the neo-thumb like normal thumb. In congenitally absent thumbs clearly support the fact that the pollicized digit is used by most patients and is not ignored or bypassed.
Assuntos
Dedos/cirurgia , Deformidades Congênitas da Mão/cirurgia , Polegar/anormalidades , Polegar/cirurgia , Pré-Escolar , Seguimentos , Deformidades Congênitas da Mão/diagnóstico por imagem , Humanos , Radiografia , Fatores de Tempo , Resultado do TratamentoRESUMO
In congenital absence of fingers or in post-traumatic amputations of the thumb or fingers, reconstruction by microsurgical toe-to-hand transfer is becoming a common treatment for these difficult problems. In case of congenital absence of the thumb, fingers, or both, these transfers can provide acceptable growth, function and sensation of the transferred toes with a current success rate usually greater than 95%. The most commonly transplanted toe is the second toe, since it is the longest toe and combines all the useful characteristics of a finger (such as joint, a nail, sensitive pulp tissue, and the ability to growth) with a good reliable blood supply. In this article, we discuss the rationale for this treatment approach, by considering the indications to treatment, the patient's preoperatory assessment, and the long-term results. We also report a case of a 4-year-old female child, suffering from congenital partial absence of second finger of the left hand, who underwent reconstruction by transfer of the second toes of foot.
Assuntos
Dedos/anormalidades , Dedos/cirurgia , Dedos do Pé/transplante , Pré-Escolar , Feminino , HumanosRESUMO
PURPOSE: To evaluate the activity of the antitumor enzyme L: -asparaginase (ASNase) on tumor cells of mesenchymal origin and the contribution of glutamine synthetase (GS) to the adaptation to the metabolic stress caused by the anti-tumor enzyme. METHODS: We studied the effects of ASNase in six human sarcoma cell lines: HT1080 (fibrosarcoma); RD (rhabdomyosarcoma); SW872 (liposarcoma); HOS, SAOS-2, and U2OS (osteosarcoma) in the absence or in the presence of the GS inhibitor methionine L: -sulfoximine (MSO). RESULTS: HT1080 and SW872 cells were highly sensitive to ASNase-dependent cytotoxicity. In contrast, RD, SAOS-2, HOS, and U2OS cells exhibited only a partial growth suppression upon treatment with the anti-tumor enzyme. In these cell lines ASNase treatment was associated with increased levels of GS. When ASNase was used together with MSO, the proliferation of the poorly sensitive cell lines was completely blocked and a significant decrease in the IC(50) for ASNase was observed. Moreover, when ASNase treatment was carried on in the presence of MSO, HOS and U2OS osteosarcoma cells exhibited a marked cytotoxicity, with increased apoptosis. CONCLUSIONS: In human sarcoma cells (1) GS markedly contributes to the metabolic adaptation of tumor cells to ASNase and (2) the inhibition of GS activity enhances the antiproliferative and cytotoxic effects of ASNase. The two-step interference with glutamine metabolism, obtained through the combined treatment with ASNase and MSO, may provide a novel therapeutic approach that should be further investigated in human tumors of mesenchymal origin.
Assuntos
Asparaginase/farmacologia , Glutamato-Amônia Ligase/antagonistas & inibidores , Sarcoma/tratamento farmacológico , Sarcoma/enzimologia , Antineoplásicos/farmacologia , Caspases/metabolismo , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Glutamato-Amônia Ligase/metabolismo , Humanos , Metionina Sulfoximina/farmacologia , Células Tumorais CultivadasRESUMO
Sodium-dependent neutral amino acid transporter-2 (SNAT2), the ubiquitous member of SLC38 family, accounts for the activity of transport system A for neutral amino acids in most mammalian tissues. As the transport process performed by SNAT2 is highly energized, system A substrates, such as glutamine, glycine, proline and alanine, reach high transmembrane gradients and constitute major components of the intracellular amino acid pool. Moreover, through a complex array of exchange fluxes, involving other amino acid transporters, and of metabolic reactions, such as the synthesis of glutamate from glutamine, SNAT2 activity influences the cell content of most amino acids, thus determining the overall size and the composition of the intracellular amino acid pool. As amino acids represent a large fraction of cell organic osmolytes, changes of SNAT2 activity are followed by modifications in both cell amino acids and cell volume. This mechanism is utilized by many cell types to perform an effective regulatory volume increase (RVI) upon hypertonic exposure. Under these conditions, the expression of SNAT2 gene is induced and newly synthesized SNAT2 proteins are preferentially targeted to the cell membrane, leading to a significant increase of system A transport Vmax. In cultured human fibroblasts incubated under hypertonic conditions, the specific silencing of SNAT2 expression, obtained with anti-SNAT2 siRNAs, prevents the increase in system A transport activity, hinders the expansion of intracellular amino acid pool, and significantly delays cell volume recovery. These results demonstrate the pivotal role played by SNAT2 induction in the short-term hypertonic RVI and suggest that neutral amino acids behave as compatible osmolytes in hypertonically stressed cells.
Assuntos
Sistema A de Transporte de Aminoácidos/fisiologia , Aminoácidos Neutros/metabolismo , Adaptação Fisiológica , Transporte Biológico , Membrana Celular/metabolismo , Tamanho Celular , Células Cultivadas , Fibroblastos/metabolismo , Regulação da Expressão Gênica , Humanos , Soluções Hipertônicas , Interferência de RNA , RNA Interferente Pequeno , Equilíbrio HidroeletrolíticoRESUMO
A0, a Cu(II) thioxotriazole complex, produces severe cytotoxic effects on HT1080 human fibrosarcoma cells with a potency comparable to that exhibited by cisplatin. A0 induced a characteristic series of changes, hallmarked by the formation of eosin- and Sudan Black-B-negative vacuoles. No evidence of nuclear fragmentation or caspase-3 activation was detected in cells treated with A0 which, rather, inhibited cisplatin-stimulated caspase-3 activity. Membrane functional integrity, assessed with calcein and propidium iodide, was spared until the late stages of the death process induced by the copper complex. Vacuoles were negative to the autophagy marker monodansylcadaverine and their formation was not blocked by 3-methyladenine, an inhibitor of autophagic processes. Negativity to the extracellular marker pyranine excluded vacuole derivation from the extracellular fluid. Ultrastructural analysis indicated that A0 caused the appearance of many electronlight cytoplasmic vesicles, possibly related to the endoplasmic reticulum, which progressively enlarge and coalesce to form large vacuolar structures that eventually fill the cytoplasm. It is concluded that A0 triggers a non-apoptotic, type 3B programmed cell death (Clarke in Anat Embryol (Berl) 181:195-213, 1990), characterized by an extensive cytoplasmic vacuolization. This peculiar cytotoxicity pattern may render the employment of A0 to be of particular interest in apoptosis-resistant cell models.
Assuntos
Antineoplásicos/farmacologia , Autofagia , Fibrossarcoma/ultraestrutura , Compostos Organometálicos/farmacologia , Triazóis/farmacologia , Apoptose , Linhagem Celular Tumoral , Cisplatino/farmacologia , Humanos , Vacúolos/ultraestruturaRESUMO
System A is a secondary active, sodium dependent transport system for neutral amino acids. Strictly coupled with Na,K-ATPase, its activity determines the size of the intracellular amino acid pool, through a complex network of metabolic reaction and exchange fluxes. Many hormones and drugs affect system A activity in specific cell models or tissues. In all the cell models tested thus far the activity of the system is stimulated by amino acid starvation, cell cycle progression, and the incubation under hypertonic conditions. These three conditions produce marked alterations of cell volume. The stimulation of system A activity plays an important role in cell volume restoration, through an expansion of the intracellular amino acid pool. Under normal conditions, system A substrates represent a major fraction of cell compatible osmolytes, organic compounds that exert a protein stabilizing effect. It is, therefore, likely that the activation of system A represents a portion of a more complex response triggered by exposure to stresses of various nature. Since system A transporters have been recently cloned, the molecular bases of these regulatory mechanisms will probably be elucidated in a short time.
Assuntos
Sistemas de Transporte de Aminoácidos/química , Aminoácidos/metabolismo , Sistemas de Transporte de Aminoácidos/metabolismo , Animais , Transporte Biológico , Membrana Celular/metabolismo , Humanos , Cinética , Modelos Biológicos , Osmose , Ligação Proteica , Isoformas de Proteínas , Sódio/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismoRESUMO
The expression of the osmosensitive sodium/myo-inositol cotransporter (SMIT) is regulated by multiple tonicity-responsive enhancers (TonEs) in the 5'-flanking region of the gene. In response to hypertonicity, the nuclear abundance of the transcription factor TonE-binding protein (TonEBP) is increased, and the transcription of the SMIT gene is induced. Transport system A for neutral amino acids, another osmosensitive mechanism, is progressively stimulated if amino acid substrates are not present in the extracellular compartment. Under this condition, as in hypertonicity, cells shrink and mitogen-activated protein kinases are activated. We demonstrate here that a clear-cut nuclear redistribution of TonEBP, followed by SMIT expression increase and inositol transport activation, is observed after incubation of cultured human fibroblasts in Earle's balanced salts (EBSS), an isotonic, amino acid-free saline. EBSS-induced SMIT stimulation is prevented by substrates of system A, although these compounds do not compete with inositol for transport through SMIT. We conclude that the incubation in isotonic, amino acid-free saline triggers an osmotic stimulus and elicits TonEBP-dependent responses like hypertonic treatment.
Assuntos
Aminoácidos/farmacologia , Proteínas de Transporte/metabolismo , Proteínas de Choque Térmico/metabolismo , Proteínas de Membrana , Pele/citologia , Pele/metabolismo , Simportadores , Transativadores/metabolismo , Adolescente , Transporte Biológico/efeitos dos fármacos , Transporte Biológico/fisiologia , Núcleo Celular/metabolismo , Tamanho Celular/efeitos dos fármacos , Tamanho Celular/fisiologia , Células Cultivadas , Fibroblastos/citologia , Fibroblastos/metabolismo , Humanos , Inositol/metabolismo , Soluções Isotônicas/farmacologia , Masculino , Pressão Osmótica , Solução Salina Hipertônica/farmacologia , Sódio/metabolismo , Fatores de TranscriçãoRESUMO
The activity of transport system A for neutral amino acids is adaptively stimulated upon amino acid starvation. In cultured human fibroblasts this treatment causes an increase in the expression of the ATA2 system A transporter gene. ATA2 mRNA increase and transport stimulation are suppressed by system A substrates, but they are unaffected by other amino acids. Supplementation of amino acid-starved cells with substrates of system A causes a decrease in both ATA2 mRNA and system A transport activity. These results suggest a direct relationship between ATA2 expression and system A transport activity.
Assuntos
Proteínas de Transporte/biossíntese , Sistemas de Transporte de Aminoácidos , Northern Blotting , Linhagem Celular , Meios de Cultura/metabolismo , Fibroblastos/metabolismo , Humanos , Prolina/metabolismo , Transporte Proteico , RNA Mensageiro/metabolismo , Fatores de TempoRESUMO
Amino acid starvation markedly stimulates the activity of system A, a widely distributed transport route for neutral amino acids. The involvement of MAPK (mitogen-activated protein kinase) pathways in this adaptive increase of transport activity was studied in cultured human fibroblasts. In these cells, a 3-fold stimulation of system A transport activity required a 6-h amino acid-free incubation. However, a rapid tyrosine phosphorylation of ERK (extracellular regulated kinase) 1 and 2, and JNK (Jun N-terminal kinase) 1, but not of p38, was observed after the substitution of complete medium with amino acid-free saline solution. ERK1/2 activity was 4-fold enhanced after a 15-min amino acid-free incubation and maintained at stimulated values thereafter. A transient, less evident stimulation of JNK1 activity was also detected, while the activity of p38 was not affected by amino acid deprivation. PD98059, an inhibitor of ERK1/2 activation, completely suppressed the adaptive increase of system A transport activity that, conversely, was unaffected by inhibitors of other transduction pathways, such as rapamycin and wortmannin, as well as by chronic treatment with phorbol esters. In the presence of either L-proline or 2-(methylaminoisobutyric) acid, two substrates of system A, the transport increase was prevented and no sustained stimulation of ERK1/2 was observed. To identify the stimulus that maintains MAPK activation, cell volume was monitored during amino acid-free incubation. It was found that amino acid deprivation caused a progressive cell shrinkage (30% after a 6-h starvation). If proline was added to amino acid-starved, shrunken cells, normal values of cell volume were rapidly restored. However, proline-dependent volume rescue was hampered if cells were pretreated with PD98059. It is concluded that (a) the triggering of adaptive increase of system A activity requires a prolonged activation of ERK1 and 2 and that (b) cell volume changes, caused by the depletion of intracellular amino acid pool, may underlie the activation of MAPKs.
Assuntos
Aminoácidos/metabolismo , Proteínas de Transporte/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Androstadienos/farmacologia , Transporte Biológico , Tamanho Celular/efeitos dos fármacos , Meios de Cultura , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/farmacologia , Fibroblastos , Flavonoides/farmacologia , Humanos , Soluções Hipertônicas , Proteínas Quinases JNK Ativadas por Mitógeno , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno , Fosforilação , Prolina/farmacologia , Sirolimo/farmacologia , Wortmanina , beta-Alanina/análogos & derivados , beta-Alanina/farmacologiaRESUMO
Protein kinase C (PKC) activation stimulates transport system X-AG for anionic amino acids in cultured human fibroblasts (Franchi-Gazzola, R., Visigalli, R., Bussolati, O., and Gazzola, G. C. (1994) FEBS Lett. 352, 109-112). To identify which PKC isoform is responsible for this effect, aspartate transport through system X-AG, PKC activity, and the subcellular distribution of PKC isoforms have been studied before and after treatment with phorbol 12, 13-dibutyrate (PDBu) in fibroblasts maintained at low serum for 1 (control cells) or 7 days (quiescent cells). In control cells aspartate transport and PKC activity in the particulate fraction were stimulated by short term PDBu treatment; both stimulatory effects were down-regulated by a prolonged exposure to the phorbol. In contrast, in quiescent cells aspartate transport and particulate PKC activity were higher than control under basal conditions, unaffected by a short term PDBu treatment, and lowered by a prolonged incubation with the phorbol. In both control and quiescent cells a short term PDBu treatment modified PKCalpha distribution, increasing its membrane-associated fraction. PKCdelta was mostly in the soluble fraction and scarcely sensitive to PDBu. A brief exposure to PDBu increased membrane-associated PKCepsilon in control but not in quiescent cells. In these cells epsilon isoform was found exclusively in the particulate fraction even in PDBu-untreated cells. A prolonged PDBu treatment caused a partial down-regulation of membrane-associated PKCepsilon in control cells and its marked decrease in quiescent cells. It is concluded that PKC-dependent changes in system X-AG activity parallel the behavior of PKCepsilon, thus suggesting a specific role for this isoform in system X-AG regulation.