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1.
J Eur Acad Dermatol Venereol ; 35(3): 693-700, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32916767

RESUMO

BACKGROUND: Brodalumab was efficacious and safe in moderate-to-severe plaque-type psoriasis in the AMAGINE trials; published reports under real-life conditions are limited. OBJECTIVES: To evaluate the effectiveness and safety of brodalumab in patients with moderate-to-severe plaque-type psoriasis in a real-world setting. METHODS: This observational, retrospective study enrolled adult patients (≥18 years) with moderate-to-severe plaque-type psoriasis who underwent 24 weeks of treatment with brodalumab at 17 Italian dermatological centres. Baseline data included demographics, comorbidities, age of onset and duration of psoriasis and previous treatments. Psoriasis Area and Severity Index (PASI), Physician Global Assessment (PGA), static PGA of Genitalia, Dermatology Life Quality Index and patient satisfaction were assessed at weeks 0, 4, 12 and 24; adverse events were recorded. RESULTS: Seventy-eight patients (mean age 47.9 years, 71.8% male, average disease duration 16.8 years) were enrolled. A rapid and significant reduction in mean PASI score was observed after 4 weeks of treatment, decreasing further at weeks 12 and 24 (all P < 0.0001 vs. baseline). A higher number of cardiometabolic comorbidities and previous therapies were negatively associated with the achievement of PASI 90 at all assessments. Brodalumab was effective in bio-experienced patients, including those who had failed on anti-interleukin (IL)-17 therapies. Quality of life and patient satisfaction increased significantly during treatment (P < 0.0001 and P < 0.01 vs. baseline, respectively). Treatment was interrupted in 9 (11.5%) patients due to adverse events (n = 4), lack of efficacy (n = 3), lost to follow-up (n = 1) and surgical procedure (n = 1). CONCLUSIONS: Brodalumab is effective and safe in the treatment of moderate-to-severe psoriasis in a real-world setting, including in patients with failure to anti-IL17 therapies.


Assuntos
Psoríase , Qualidade de Vida , Adulto , Anticorpos Monoclonais , Anticorpos Monoclonais Humanizados , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Psoríase/tratamento farmacológico , Estudos Retrospectivos , Índice de Gravidade de Doença , Resultado do Tratamento
2.
J Eur Acad Dermatol Venereol ; 31(12): 2069-2076, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28573714

RESUMO

BACKGROUND: Dermatofibrosarcoma protuberans (DFSP) is a rare, low-grade mesenchymal skin tumour, characterized by slow infiltrative growth and common local recurrence, with infrequent distant metastases. OBJECTIVE: The aim of this study is to better clarify clinicopathological characteristics of this tumour and to evaluate the cure rates of Mohs Tübingen technique (MTT) and wide local excision (WLE). Eventually, we perform a literature review to compare our experience with published data. METHODS: A retrospective review was conducted on 135 patients diagnosed, treated and followed up between 1997 and 2014 at two different institutions. Sixty-two patients underwent to WLE and 73 to MTT. The primary end-points were the following: percentage of recurrences, time to progression and recurrence annual risk rate. Then, the PubMed database was searched for DFSP case series treated with standard surgical resection (SSR), WLE, Mohs' micrographic surgery (MMS) and MTT. The annual risk rate of recurrence calculated and reported for the four separate procedures was pooled to compare them. RESULTS: Five of the 62 patients with WLE (8.1%) experienced recurrences after a mean follow-up of 4.7 years; the percentage of recurred patients 9 years after MTT was 5.5%, and the annual recurrence risk rate of 0.6%. Pooling these data with those from literature, the recurrence rate varies from 26% to 60% for SSR, from 0% and 41% for WLE, from 0% and 8.3% for MMS and from 0% to 5.5% for MTT. The lowest annual recurrence risk rate was found for MTT. CONCLUSION: Significantly lower recurrence rates were recorded in patients treated with classic or Tübingen Mohs' technique. To the best of our knowledge, our case series is the widest treated with MTT ever described in the literature; these data may be useful to guide clinicians in the choice of the gold standard treatment for Dermatofibrosarcoma protuberans.


Assuntos
Dermatofibrossarcoma/cirurgia , Neoplasias Cutâneas/cirurgia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Procedimentos Cirúrgicos Dermatológicos/métodos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Cirurgia de Mohs/métodos , Recidiva Local de Neoplasia/cirurgia , Estudos Retrospectivos , Adulto Jovem
5.
G Ital Dermatol Venereol ; 148(5): 443-51, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24005136

RESUMO

AIM: The aim of this study was to review our experience with regards to patients with cutaneous melanoma diagnosed from 1983 to 2009, followed-up in our Dermatological Department of Novara. METHODS: A retrospective study of 762 patients diagnosed with cutaneous melanoma in the Dermatological Department of Novara between 1983 and 2009 was conducted. Information was extracted from our melanoma patient database. The database included demographical, clinical and pathological variables of the patient. Clinical and pathological factors predicting survival were analyzed using the Kaplan-Meier curves and the Log-Rank Test (univariate analysis). RESULTS: Staging (American Joint Committee on Cancer 2001) of patients (P=0.000), Breslow thickness (P=0.000), primary ulceration and regression of the lesion (P=0.000), type of first (P<0.039) and second recurrence (P<0.011) were strongly correlated with overall and disease free survival. Sentinel lymph node biopsy was not correlated with disease free survival (P=0.153), it influences only overall survival (P=0.007) CONCLUSION: Our results confirms that sentinel node biopsy, Breslow thickness, ulceration, regression, staging, first and second recurrence are important variable for overall survival and disease free survival, sentinel lymph node status influence only overall survival instead.


Assuntos
Melanoma/epidemiologia , Neoplasias Cutâneas/epidemiologia , Adulto , Idoso , Diagnóstico por Imagem , Intervalo Livre de Doença , Feminino , Seguimentos , Humanos , Itália/epidemiologia , Estimativa de Kaplan-Meier , Metástase Linfática , Masculino , Melanoma/patologia , Melanoma/secundário , Melanoma/cirurgia , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Prognóstico , Biópsia de Linfonodo Sentinela , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/cirurgia , Úlcera Cutânea/etiologia , Resultado do Tratamento
6.
J Dermatolog Treat ; 33(1): 401-407, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32349568

RESUMO

BACKGROUND: Cyclosporine A (CsA) is one of the systemic therapeutic options for moderate-to-severe psoriasis, based on its efficacy and rapidity of action. The current study investigated the response to CsA in patients with moderate-to-severe plaque psoriasis. MATERIALS AND METHODS: TRANSITION was an observational, cross-sectional, multicentre study which evaluated the proportion of partial- and suboptimal-responders among patients with moderate-to-severe plaque psoriasis treated with continuous CsA for ≥12 weeks. Patients demonstrating a Psoriasis Area and Severity Index (PASI) response of ≥90, ≥75 and <90, ≥50 and <75 and <50 were defined as responders, suboptimal-responders, partial-responders, and non-responders, respectively. RESULTS: A total of 196 patients (mean age, 46.6 years; 62.8% males) from 14 sites in Italy were evaluated. At the study visit, the mean (SD) PASI score was 4.2(5.5) compared with 15.3(7.1) prior to the last CsA cycle. For response categories, 39.8%, 22.4%, 16.8%, and 20.9% of patients were responders, suboptimal-responders, partial-responders, and non-responders to CsA treatment. Overall, 28.6% of patients permanently discontinued treatment with CsA (lack of efficacy [10.2%], poor tolerability and voluntary discontinuation [3.6% each], and other [11.7%]). CONCLUSION: Patients were only partially satisfied with CsA treatment, reporting measurable impact on quality of life. Only 40% patients showed a satisfactory response to CsA.


Assuntos
Ciclosporina , Psoríase , Estudos Transversais , Ciclosporina/uso terapêutico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Psoríase/tratamento farmacológico , Qualidade de Vida , Índice de Gravidade de Doença , Resultado do Tratamento
7.
Clin Exp Dermatol ; 36(6): 617-20, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21771005

RESUMO

We describe two nonconsanguineous white patients with multiple pigmented basal cell carcinomas (BCCs) that were histopathologically confirmed. The first patient had calcification of the cerebral falx, multiple keratocysts in the jaw, and other malformations of the cranial and finger bones. The second patient presented with multiple dermoid cysts, calcification of the cerebral falx, keratocysts of the mandible, and agenesis of left kidney. Both patients had palmar pits. Both denied any family history of cutaneous tumours. On dermatoscopic examination of patient 1, multiple, bluish, confluent and large globules were seen. The second patient had blue ovoid globules, arborizing vessels, and areas shaped like maple leaves and spoke-wheels. Based on the clinical and radiological features we diagnosed both patients as having Gorlin syndrome (GS). To our knowledge, there are no previous reports of white patients with GS showing only pigmented BCCs. The dermatoscopic patterns were different in the two patients, and to our knowledge, this is the first report of a patient with GS showing a spoked-wheel dermatoscopic pattern.


Assuntos
Síndrome do Nevo Basocelular/patologia , Neoplasias Ósseas/patologia , Carcinoma Basocelular/patologia , Neoplasias Cutâneas/patologia , Adulto , Dermoscopia , Síndrome do Hamartoma Múltiplo , Humanos , Masculino , Pessoa de Meia-Idade , Nevo Pigmentado/patologia
8.
J Dermatolog Treat ; 32(5): 507-513, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31647347

RESUMO

BACKGROUND: Dupilumab, a fully human monoclonal antibody targeting the alpha subunit of IL-4 was recently approved for the treatment of moderate-to-severe atopic dermatitis (AD) in adult patients. OBJECTIVE: To assess dupilumab effectiveness and safety in adults with moderate-to-severe AD in a real-life Italian multicentre retrospective cohort. METHODS: Adult moderate-to-severe AD patients, referring to 39 Italian centers, received dupilumab in the context of a national patient access program. Disease assessment was performed at baseline, after 4 and 16 weeks of treatment using Eczema-Area-and-Severity-Index (EASI) score, itch and sleep numerical-rating-score (itch-NRS, sleep-NRS) and Dermatology-Life-Quality-Index (DLQI). RESULTS: A total of 109 (71 M/38F) patients was studied. There was a significant reduction in EASI score, itch-NRS, sleep-NRS and DLQI from baseline to week 4 and a further significant decline to week 16. EASI 50, EASI75 and EASI90 were achieved by 59.6%, 28.4% and 9.3% of patients at 4 weeks and by 87.2%, 60.6% and 32.4% of them at 16 weeks, respectively. Adverse events were experienced by 19.2% (21/109) of the patients and they were all mild in intensity, being conjunctivitis the most common side effect. CONCLUSIONS: Dupilumab significantly improved disease severity, pruritus, sleep loss and quality of life with an acceptable safety profile.


Assuntos
Anticorpos Monoclonais Humanizados/administração & dosagem , Dermatite Atópica/tratamento farmacológico , Prurido , Qualidade de Vida , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prurido/tratamento farmacológico , Estudos Retrospectivos , Índice de Gravidade de Doença , Sono , Resultado do Tratamento , Adulto Jovem
9.
Clin Exp Dermatol ; 34(8): e972-4, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19758385

RESUMO

In recent years, vitamin D3 analogues have become one of the most widely prescribed topical treatments for mild or moderate chronic plaque psoriasis. These molecules are effective and safe, but their exact mechanism of action is not completely understood. In vitro studies have shown that D3 analogues decrease proliferation and induce differentiation of keratinocytes, and have strong immunomodulating effects, but there are no conclusive data about apoptosis. The aim of this study was to evaluate differences in apoptotic response between lesional and perilesional keratinocytes of patients with psoriasis before and after treatment with calcipotriol, a synthetic vitamin D3 analogue. Keratinocytes were isolated from psoriatic plaques including lesional and perilesional skin, and cultured. Cells were treated with calcipotriol for 20 h and examined under confocal microscopy after staining with propidium iodide. The number of apoptotic cells after incubation with calcipotriol was significantly higher in lesional than in perilesional keratinocytes (P < 0.05) or non-treated psoriatic keratinocytes (P < 0.05). In conclusion, calcipotriol seems to induce apoptosis in psoriatic keratinocytes.


Assuntos
Apoptose/efeitos dos fármacos , Calcitriol/análogos & derivados , Fármacos Dermatológicos/farmacologia , Queratinócitos/efeitos dos fármacos , Psoríase/tratamento farmacológico , Adolescente , Adulto , Idoso , Calcitriol/farmacologia , Feminino , Humanos , Queratinócitos/fisiologia , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Psoríase/patologia , Adulto Jovem
10.
IUCrJ ; 6(Pt 3): 357-365, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31098017

RESUMO

The routine atomic resolution structure determination of single particles is expected to have profound implications for probing structure-function relationships in systems ranging from energy-storage materials to biological molecules. Extremely bright ultrashort-pulse X-ray sources - X-ray free-electron lasers (XFELs) - provide X-rays that can be used to probe ensembles of nearly identical nanoscale particles. When combined with coherent diffractive imaging, these objects can be imaged; however, as the resolution of the images approaches the atomic scale, the measured data are increasingly difficult to obtain and, during an X-ray pulse, the number of photons incident on the 2D detector is much smaller than the number of pixels. This latter concern, the signal 'sparsity', materially impedes the application of the method. An experimental analog using a conventional X-ray source is demonstrated and yields signal levels comparable with those expected from single biomolecules illuminated by focused XFEL pulses. The analog experiment provides an invaluable cross check on the fidelity of the reconstructed data that is not available during XFEL experiments. Using these experimental data, it is established that a sparsity of order 1.3 × 10-3 photons per pixel per frame can be overcome, lending vital insight to the solution of the atomic resolution XFEL single-particle imaging problem by experimentally demonstrating 3D coherent diffractive imaging from photon-sparse random projections.

11.
J Eur Acad Dermatol Venereol ; 22(10): 1168-72, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18410335

RESUMO

BACKGROUND: Chronic venous leg ulcers represent an urgent and increasing problem for public health. The use of skin autografts results in a greater therapeutic success in healing chronic ulcers. OBJECTIVE: A simple method of skin autografting that could permit a wider use of skin grafts in outpatients is needed. A new technique allowing skin autografting in a simple one-step process, without complex surgical procedures or expensive technical supplies, is presented. METHODS: A small, full-thickness skin specimen taken from the patient is finely minced and spread on his leg ulcer bed allowing to cover a surface many times wider than the sample itself. RESULTS: This method induces faster re-epithelization of chronic leg ulcers that failed to heal despite good conservative local therapy and give the possibility to repair very large ulcers with small fragments of skin. A clinical case is shown as an example out of 20 ulcers we recently treated. CONCLUSION: Our preliminary report shows that this technique results in a greater therapeutic success (18 of 20 cases) in healing chronic leg ulcers, a common pathology that often affects outpatients treated for very long periods at home or in the Dermatologist's office. In our experience, this new and successful reparative possibility makes 'mince grafting' a recommendable procedure.


Assuntos
Úlcera da Perna/cirurgia , Transplante de Pele , Transplante Autólogo , Úlcera Varicosa/cirurgia , Doença Crônica , Feminino , Humanos , Masculino
12.
Ann Dermatol Venereol ; 134(1): 31-4, 2007 Jan.
Artigo em Francês | MEDLINE | ID: mdl-17384539

RESUMO

BACKGROUND: Dermatofibrosarcoma protuberans is a rare cutaneous sarcoma that progresses slowly. Although it exhibits pronounced local aggressiveness, it rarely metastasises. The condition is difficult to treat on account of asymmetric and unpredictable growth as well as the frequency of relapse. Treatment is primarily surgical. PATIENTS AND METHODS: We report 31 cases of dermatofibrosarcoma protuberans operated at the Dermatology Clinic of Novara between 1997 and 2004 using the Tübingen technique. An immunohistochimical study was performed and screening was carried out for possible extension of the neoplasm into muscle. RESULTS: Muscular involvement was seen in 4 cases. No relapses were seen over a median survival period of 3 years and no patients were lost to follow-up. DISCUSSION: The Mohs technique is the surgical method of reference and allows tumour eradication with sparing of healthy tissue. The Tübingen method constitutes an alternative approach requiring fewer histological sections. The results obtained in our series were good and no relapses were seen over a median survival period of 3 years.


Assuntos
Dermatofibrossarcoma/cirurgia , Neoplasias Cutâneas/cirurgia , Adulto , Idoso , Dermatofibrossarcoma/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Cutâneas/patologia , Procedimentos Cirúrgicos Operatórios/métodos
14.
Ann Dermatol Venereol ; 132(6-7 Pt 1): 540-3, 2005.
Artigo em Francês | MEDLINE | ID: mdl-16142102

RESUMO

INTRODUCTION: Chordomas are rare extradural bone tumors arising from notochord remnants, the embryonic structure forming the original axis of the spine. They represent 0.1p. 100 of all intra-cranial tumors. The chordoma is a locally malignant cancer that tends to invade the surrounding tissues. Its localization in the skin is exceptional. OBSERVATION: A 56 year-old man developed a nut-sized vegetating nodule on the nasal groove. This lesion appeared a few months following surgery for a frontoglabellar relapse of a chordoma that had developed six years earlier at the base of the skull. DISCUSSION: We report this case because of the rareness of cutaneous involvement and the particular conditions in which it occurred. It may have been due to tumoral seeding during the previous surgical interventions.


Assuntos
Cordoma/secundário , Neoplasias Cutâneas/secundário , Neoplasias da Base do Crânio/patologia , Cordoma/cirurgia , Face/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias Cutâneas/cirurgia , Neoplasias da Base do Crânio/cirurgia
15.
Cell Death Differ ; 18(6): 948-58, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21151024

RESUMO

p75 neurotrophin receptor (p75NTR) belongs to the TNF-receptor superfamily and signals apoptosis in many cell settings. In human epidermis, p75NTR is mostly confined to the transit-amplifying (TA) sub-population of basal keratinocytes. Brain-derived neurotrophic factor (BDNF) or neurotrophin-4 (NT-4), which signals through p75NTR, induces keratinocyte apoptosis, whereas ß-amyloid, a ligand for p75NTR, triggers caspase-3 activation to a greater extent in p75NTR transfected cells. Moreover, p75NTR co-immunoprecipitates with NRAGE, induces the phosphorylation of c-Jun N-terminal kinase (JNK) and reduces nuclear factor kappa B (NF-κB) DNA-binding activity. p75NTR also mediates pro-NGF-induced keratinocyte apoptosis through its co-receptor sortilin. Furthermore, BDNF or ß-amyloid cause cell death in TA, but not in keratinocyte stem cells (KSCs) or in p75NTR silenced TA cells. p75NTR is absent in lesional psoriatic skin and p75NTR levels are significantly lower in psoriatic than in normal TA keratinocytes. The rate of apoptosis in psoriatic TA cells is significantly lower than in normal TA cells. BDNF or ß-amyloid fail to induce apoptosis in psoriatic TA cells, and p75NTR retroviral infection restores BDNF- or ß-amyloid-induced apoptosis in psoriatic keratinocytes. These results demonstrate that p75NTR has a pro-apoptotic role in keratinocytes and is involved in the maintenance of epidermal homeostasis.


Assuntos
Apoptose , Queratinócitos/metabolismo , Psoríase/metabolismo , Receptor de Fator de Crescimento Neural/metabolismo , Transdução de Sinais , Proteínas Adaptadoras de Transporte Vesicular/genética , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Peptídeos beta-Amiloides , Fator Neurotrófico Derivado do Encéfalo/genética , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Caspase 3/genética , Caspase 3/metabolismo , Linhagem Celular , Ativação Enzimática/genética , Humanos , Queratinócitos/patologia , NF-kappa B/genética , NF-kappa B/metabolismo , Psoríase/genética , Receptor de Fator de Crescimento Neural/genética
17.
J Eur Acad Dermatol Venereol ; 19(6): 722-4, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16268878

RESUMO

Thysanoptera dermatitis is caused by the bite of small (1-2 mm) insects (generally thrips). Thrips usually feed on the juices of vegetables but if they reach human skin they can suck the epidermal lymph after biting. The cutaneous lesions formed are small pink and itchy papules localized mainly on the trunk and the arms. Diagnosis is only possible by demonstrating that the insect is present inside one of the lesions of the skin. Thysanoptera dermatitis is often misdiagnosed as mosquito bites. Although self-resolving in a few days, Thysanoptera dermatitis should be known not only for the cultural and scientific training of the dermatologist but also to add more detailed diagnostic information to the generic diagnosis of 'entomodermatosis' and to confirm the benign evolution of the bites.


Assuntos
Dermatite/diagnóstico , Dermatite/parasitologia , Hemípteros , Mordeduras e Picadas de Insetos/diagnóstico , Adulto , Animais , Dermatite/tratamento farmacológico , Diagnóstico Diferencial , Humanos , Mordeduras e Picadas de Insetos/tratamento farmacológico , Masculino , Pomadas , Esteroides/uso terapêutico
18.
J Microsc ; 172(Pt 1): 31-9, 1993 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8289226

RESUMO

Confocal microscopes provide clear, thin optical sections with little disturbance from regions of the specimen that are not in focus. In addition, they appear to provide somewhat greater lateral and axial image resolution than with non-confocal microscope optics. To address the question of resolution and contrast transfer of light microscopes, a new test slide that enables the direct measurement of the contrast transfer characteristics (CTC) of microscope optics at the highest numerical aperature has been developed. With this new test slide, the performance of a confocal scanning laser microscope operating in the confocal reflection mode and the non-confocal transmission mode was examined. The CTC curves show that the confocal instrument maintains exceptionally high contrast (up to twice that with non-confocal optics) as the dimension of the object approaches the diffraction limit of resolution; at these dimensions, image detail is lost with non-confocal microscopes owing to a progressive loss of image contrast. Furthermore, we have calculated theoretical CTC curves by modelling the confocal and non-confocal imaging modes using discrete Fourier analysis. The close agreement between the theoretical and experimental CTC curves supports the earlier prediction that the coherent confocal and the incoherent non-confocal imaging mode have the same limit of resolution (defined here as the inverse of the spatial frequency at which the contrast transfer converges to zero). The apparently greater image resolution of the coherent confocal optics is a consequence of the improved contrast transfer at spacings which are close to the resolution limit.


Assuntos
Microscopia/métodos , Diatomáceas/ultraestrutura , Microscopia/instrumentação , Óptica e Fotônica
19.
J Biol Chem ; 258(10): 6486-91, 1983 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-6222044

RESUMO

The eucaryotic microorganism, Neurospora crassa, is able under specified conditions (Zamir, L.O., Jung, E., and Jensen, R.A. (1982) J. Biol. Chem. 258, 6492-6496) to synthesize a cyclohexadienyl derivative of prephenic acid having the novel structure of a spiro-gamma-lactam. This L-gamma-(spiro-4-hydroxy-2,5-cyclohexadienyl)-pyroglutamate is herein given the trivial name, spiro-arogenate, to indicate its close relationship to the amino acid, L-arogenate. Spiro-arogenate is quantitatively converted to phenylalanine at mildly acidic pH and can be converted to arogenate by boiling at basic pH. The structure of spiro-arogenate was established through the application of spectroscopic techniques (ultraviolet, 1H-NMR, 13C-NMR, and mass spectrometry). The 1H-NMR and 13C-NMR spectra of spiro-arogenate isolated as the natural product conformed to the spectrum of spiro-arogenate prepared by chemical synthesis by S. Danishefsky and co-workers (Danishefsky, S., Morris, J., and Clizbe, L.A. (1981) J. Am. Chem. Soc. 103, 1602-1604). Circular dichroism established the S configuration of the asymmetric carbon at C-8 of spiro-arogenate.


Assuntos
Neurospora crassa/análise , Neurospora/análise , Pirrolidinonas/isolamento & purificação , Ácido Pirrolidonocarboxílico/isolamento & purificação , Aminoácidos Dicarboxílicos , Fenômenos Químicos , Química , Dicroísmo Circular , Cicloexenos , Temperatura Alta , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Espectrometria de Massas , Fenilalanina , Ácido Pirrolidonocarboxílico/análogos & derivados , Tirosina/análogos & derivados
20.
Biochemistry ; 24(7): 1607-12, 1985 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-3924095

RESUMO

L-Arogenate, an immediate precursor of either L-tyrosine, L-phenylalanine, or both in many microorganisms and plants, may undergo two types of dehydration reactions that yield products of increased stability. Under acidic conditions, a facile aromatization attended by loss of the C-4 hydroxyl and the C-1 carboxyl moieties results in quantitative conversion to L-phenylalanine. When aromatization was largely prevented by maintaining pH in the range of 7.5-12, a second dehydration reaction occurred in which the alanyl side chain and the carboxyl group at C-1 formed a lactam ring to yield spiro-arogenate. The latter reaction occurs at 100 degrees C, roughly 50% conversion being obtained in 2 h. The product formed from L-arogenate was authentic spiro-arogenate, as demonstrated by high-performance liquid chromatography and thin-layer chromatography identification procedures. Further confirmation was obtained by 1H nuclear magnetic resonance, ultraviolet spectroscopy, and mass spectrometry. Thus far, the conversion of L-arogenate to spiro-arogenate is not known to be enzyme catalyzed. The other dehydratase reaction, however, is catalyzed in nature by an enzyme denoted arogenate dehydratase. An improved assay is described for this in which [3H]dansyl derivatives of L-arogenate (substrate) and L-phenylalanine (product) are separated by using bidimensional thin-layer chromatography. The radioactive reaction product is then quantitated. This assay was used to study partially purified arogenate dehydratase from Pseudomonas diminuta, an organism that depends upon the arogenate pathway for L-phenylalanine biosynthesis.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Aminoácidos Dicarboxílicos/metabolismo , Hidroliases/metabolismo , Tirosina/análogos & derivados , Cicloexenos , Hidroliases/antagonistas & inibidores , Fenilalanina/farmacologia , Pseudomonas/metabolismo , Pseudomonas aeruginosa/metabolismo , Ácido Pirrolidonocarboxílico/análogos & derivados , Ácido Pirrolidonocarboxílico/metabolismo , Especificidade da Espécie , Tirosina/metabolismo
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