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1.
Prog Urol ; 21(2): 126-33, 2011 Feb.
Artigo em Francês | MEDLINE | ID: mdl-21296281

RESUMO

OBJECTIVES: To assess the prevalence, the severity and expectations regarding erectile dysfunction (ED) in diabetic patients, then to investigate how general practitioners (GP) and endocrinologists manage this disorder. PATIENTS AND METHODS: A questionnaire was given during 5 weeks to every diabetic patient addressed to the endocrinology department in order to assess erectile function (IIEF5), patient's bother and expectations to be treated, and the management of ED by GP and endocrinologists and differences in management between male and female doctors. RESULTS: One hundred and thirty questionnaires were available. Mean age was 57.5 and the mean IIEF5 score was 13.6. Twenty-two patients (16.9%) reported an IIEF5 score less than 5 and 75 patients (57,6%) reported an IIEF5 between 5 and 20. Eighty-six patients declared ED (66.2%). In these patients, 76 (88.4%) sought for a medical treatment and 11 (12.8%) received a treatment for ED. Endocrinologists were more active than GP in the screening of ED (59.5% vs 19.4%, P=0.001) but prescribed a treatment less often (14.3% vs 45.2%, P=0.008). Female doctors seemed less active in ED management (29.3% vs 13.3%, NS). CONCLUSIONS: This study highlighted the lack of ED management by GT and endocrinologists in diabetic patients in spite of ED's frequency and patients' expectations.


Assuntos
Complicações do Diabetes/terapia , Endocrinologia , Disfunção Erétil/terapia , Medicina Geral , Padrões de Prática Médica , Adulto , Idoso , Idoso de 80 Anos ou mais , Complicações do Diabetes/epidemiologia , Disfunção Erétil/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Índice de Gravidade de Doença , Inquéritos e Questionários , Adulto Jovem
2.
Gynecol Obstet Fertil Senol ; 49(3): 193-203, 2021 03.
Artigo em Francês | MEDLINE | ID: mdl-32916317

RESUMO

OBJECTIVES: The aim of this review is to summarize the development of UT on worldwide and to develop the new questions posed by this technique in 2020. METHODS: According to the PRISMA model, via Pubmed, we searched for publications containing the keywords: uterus transplantation; UT and cryopreservation from 2000 to 2020. RESULTS: At least 76 UTx have been carried out around the world and 19 healthy babies were born. The main indication remains the uterine agenesis (MRKH Syndrome>85% cases) then the history of hysterectomy (hemorrhage of the delivery or cervical cancer) and the non-functional uterus (Asherman's syndrome, diffuse adenomyosis). The 2 types of donors (living and deceased) are developed representing respectively 75% and 25% of the TU; the success rate in terms of return of rules is better in the living donor group and is 79% vs 68% in the deceased donor group. The choice of donor type must take into account the constraints of both procedures. Surgical complications (grade III) for the donor are estimated to be 14% mainly represented by ureter wounds. Technical simplifications concerning the venous return of the graft but also the carrying out of robot-assisted surgery would reduce the operating time for the donor and facilitate the collection process. CONCLUSION: TU is a complementary alternative to GPA and adoption allowing patients to be surrogates, legal and biological of the baby. An extension of the indications to patients with non absolute uterine infertility is in the process of democratization.


Assuntos
Transtornos 46, XX do Desenvolvimento Sexual , Infertilidade Feminina , Feminino , Humanos , Doadores Vivos , Ductos Paramesonéfricos , Útero/transplante
3.
Prog Urol ; 20(7): 542-4, 2010 Jul.
Artigo em Francês | MEDLINE | ID: mdl-20656279

RESUMO

The nephrectomy of a dialyzed renal insufficient patient is a frequent operation. Nevertheless, the vascular complication risks are increased for these patients. We report the case of a patient who had presented a mesenteric ischemia after a left nephrectomy. The cause of this ischemia was plurifactorial with, on one hand, a splanchnic hypoperfusion due to post-procedure hypovolemia caused by an important depletion during the dialysis as well as the use of vasoactive amines and, on the other hand, the peripheral mesenteric microvascularisation occlusion due to a kayexalate crystal deposit.


Assuntos
Isquemia/etiologia , Mesentério/irrigação sanguínea , Nefrectomia/efeitos adversos , Humanos , Masculino , Pessoa de Meia-Idade , Nefrectomia/métodos
4.
J Gynecol Obstet Hum Reprod ; 49(7): 101730, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32234354

RESUMO

The main difficulty of ovarian tissue autograft (OTA) is to preserve as many follicles as possible because the ovarian tissue undergoes warm ischemia during grafting until revascularisation, resulting in significant follicular loss. We describe a two-stage grafting technique to stimulate new vascularisation in order to enhance the revascularization process to reduce the ischemic injuries. Furthermore we performed ovarian patchwork in the laboratory and then grafting with robotic laparoscopy to facilitate surgery and increase precision. This technique is used in the DATOR study with promising results, such as a 40% delivery rate.


Assuntos
Ovário/transplante , Procedimentos Cirúrgicos Robóticos/métodos , Autoenxertos , Criopreservação , Feminino , Preservação da Fertilidade , Humanos , Laparoscopia/métodos , Gravidez , Insuficiência Ovariana Primária/etiologia , Insuficiência Ovariana Primária/cirurgia
5.
J Cell Biol ; 105(4): 1649-62, 1987 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-3667694

RESUMO

Paramecium trichocysts are unusual secretory organelles in that: (a) their crystalline contents are built up from a family of low molecular mass acidic proteins; (b) they have a precise, genetically determined shape; and (c) the crystalline trichocyst contents expand rapidly upon exocytosis to give a second, extracellular form which is also an ordered array. We report here the first step of our study of trichocyst structure. We have used a combination of x-ray powder diffraction, freeze-etching, and freeze-fracture electron microscopy of isolated, untreated trichocysts, and density measurements to show that trichocyst contents are indeed protein crystals and to determine the elementary unit cell of both the compact intracellular and the extended extracellular form.


Assuntos
Grânulos Citoplasmáticos/ultraestrutura , Exocitose , Paramecium/ultraestrutura , Animais , Fracionamento Celular , Cristalografia , Técnica de Congelamento e Réplica , Técnica de Fratura por Congelamento , Microscopia Eletrônica/métodos , Organoides/ultraestrutura , Difração de Raios X
6.
Gynecol Obstet Fertil ; 37(1): 3-10, 2009 Jan.
Artigo em Francês | MEDLINE | ID: mdl-19084460

RESUMO

OBJECTIVES: To assess the health-related quality of life (Contilife) after three surgical anti-incontinence procedures (Tension-Free Vaginal Tape [TVT], Transobturator Vaginal Tape [TOT], and Transobturator Vaginal Tape [TVT-O]). PATIENTS AND METHODS: We performed a prospective analysis of 90 women (30 TVT, 30 TOT, 30 TVT-0) with genuine stress incontinence pre- and postoperatively at 18 months. The objective cure rate was determined by clinical and urodynamic examination and the subjective cure rate by the Contilife questionnaire. RESULTS: Prior to surgery, patients complained more of effort activities, followed by global well-being. Postoperatively, all domains improved significantly without statistical difference between the three groups and 90% of the patients would advise the intervention to one of their friends. DISCUSSION AND CONCLUSION: Surgical outcomes vary greatly depending on the methodology of the study. Health-related quality of life seems paramount to decide time of surgery and to evaluate postoperatory results. We have chosen the Contilife questionnaire because of its scientific and clinical validity, reliability, responsiveness and linguistic validation. These results confirm that TVT/TOT/TVT-O procedures are a safe and effective surgical method and that they significantly improved health-related quality of life.


Assuntos
Satisfação do Paciente , Complicações Pós-Operatórias/epidemiologia , Qualidade de Vida , Incontinência Urinária por Estresse/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Pessoa de Meia-Idade , Diafragma da Pelve/cirurgia , Estudos Prospectivos , Slings Suburetrais , Telas Cirúrgicas , Inquéritos e Questionários , Resultado do Tratamento , Incontinência Urinária por Estresse/psicologia
7.
Gynecol Obstet Fertil ; 36(7-8): 800-7, 2008.
Artigo em Francês | MEDLINE | ID: mdl-18657463

RESUMO

Ovarian epithelial dysplasia has been described in the ovarian surface epithelium by histologic, morphometric and nuclear profile studies. It could represent a potential precursor of ovarian malignancy in patients with genetic risk of ovarian cancer, although its natural history and progression to carcinoma are unpredictable. Diagnosis and identification of ovarian dysplasia would certainly be useful to understand the early steps of ovarian carcinogenesis. However, dysplasia in relation with ovulation induction seems to have a different pattern. We report dysplasia definitions and the current clinical management.


Assuntos
Doenças Ovarianas/patologia , Displasia do Colo do Útero/patologia , Feminino , Genes BRCA1 , Genes BRCA2 , Humanos , Imuno-Histoquímica , Doenças Ovarianas/classificação , Doenças Ovarianas/complicações , Neoplasias Ovarianas/epidemiologia , Neoplasias Ovarianas/genética , Ovulação , Displasia do Colo do Útero/classificação , Displasia do Colo do Útero/complicações
8.
Gynecol Obstet Fertil Senol ; 46(3): 200-208, 2018 Mar.
Artigo em Francês | MEDLINE | ID: mdl-29530560

RESUMO

OBJECTIVE: To provide clinical practice guidelines from the French college of obstetrics and gynecology (CNGOF) with the Haute Autorité de santé (HAS), based on the best evidence available, concerning the diagnosis accuracy of endoscopy (laparoscopy, hysteroscopy, fertiloscopy, cystoscopy, colonoscopy) in case of endometriosis. MATERIAL AND METHODS: English and French review of literature about the diagnosis accuracy of endoscopy in case of endometriosis. RESULTS AND CONCLUSION: Laparoscopy is useful in case of suspected endometriosis in patients with symptoms or infertility when appropriate preoperative assessment is negative (grade C). Biopsies during diagnosis laparoscopy are recommended in case of typical or atypical lesions to confirm endometriosis (grade B). It is not recommended to perform fertiloscopy in case of suspected endometriosis (grade C). Hysteroscopy could be performed in case of suspected endometriosis and infertility to eliminate endometrial polyp or septate uterus (grade C). Colonoscopy is not recommended in case of suspected deep posterior endometriosis (grade C).


Assuntos
Endometriose/diagnóstico , Endoscopia , Feminino , Humanos
9.
Gynecol Obstet Fertil Senol ; 46(6): 509-513, 2018 06.
Artigo em Francês | MEDLINE | ID: mdl-29776842

RESUMO

OBJECTIVES: In case of large breast cancer, neoadjuvant chemotherapy (NAC) can be performed to reduce the size of the tumor and thus perform a conservative surgery. The place of the sentinel lymph node biopsy (SLNB) in case of NAC is still debated. The main aim of this study is to assess the risk of axillary recurrence after negative SLNB before NAC. METHODS: It is a retrospective, observational and uni-centric study. We included 18 to 80-year-old patients with unilateral breast cancer requiring a NAC and with a negative SLNB before NAC. Our primary endpoint was axillary recurrence. RESULTS: Between August 2006 and October 2016, 64 patients had a negative GS performing before a NAC and did not benefit from axillary dissection after NAC. The average duration of follow-up was 37 months. During our follow-up, we did not find any cases of axillary recurrence. CONCLUSION: This study supports the reliability of lymph node status assessment using the SLNB before CNA.


Assuntos
Neoplasias da Mama/patologia , Neoplasias da Mama/terapia , Quimioterapia Adjuvante/métodos , Terapia Neoadjuvante/métodos , Recidiva Local de Neoplasia/epidemiologia , Biópsia de Linfonodo Sentinela/métodos , Adolescente , Adulto , Idoso , Axila , Feminino , Humanos , Metástase Linfática/patologia , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Risco
10.
Eur J Obstet Gynecol Reprod Biol ; 134(1): 87-94, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16891051

RESUMO

OBJECTIVES: Prospective evaluation of outcome and complications over a 5-year period post-treatment of urinary stress incontinence by TVT, and comparison of our results with the reference studies. MATERIALS AND METHODS: About 94 patients were treated for urinary stress incontinence only by one TVT procedure (single surgical procedure), between April 1997 and December 1998; 68% of patients presented pure urinary stress incontinence and 32% mixed incontinence. We found also a 25.5% rate of sphincter deficiency (UCP < 20 cm H(2)O) in this cohort. Patients were evaluated after 5 years: 52 complete evaluations (clinical, flow measurement with measurement of post-mictional residue, 24h PAD-test, quality of life questionnaire), 30 complete telephone interviews, 12 lost to follow-up (2 patients deceased). RESULTS: About 87% of the patients had a 5-year follow-up. The success rate was 79.2% overall (84.5% for the pure urinary stress incontinence and 67% for the mixed incontinence cases), and 72.2% for the cases of associated sphincter deficiency. We had only a 13% rate of patients lost to follow-up. More than half of the urinary urgency cases were treated successfully, however with a less satisfactory outcome in cases of bladder instability. The urodynamic exploration appeared to reveal that TVT caused dysuria: 52% of patients had a maximum flowrate below 15 ml/s, but the quality of life was improved, with a 95% rate of satisfaction without functional problems. We observed no late complications such as vaginal erosion or rejection of the prolene; the de novo syndrome was rare, with 8.5% of urinary frequency, 6% of urinary urgency and only 5.7% of invalidating dysuria. We saw no cases of pelvic floor disease after TVT treatment. DISCUSSION: Our casuistry results are comparable with the reference studies by Scandinavian authors, Rezapour and Ulmsten, confirming the long-term success of the TVT procedure. Concerning the apparently elevated rates of post-TVT dysuria found by urodynamic exploration, a distinction has to be drawn between post-TVT urinary problems (frequent but oligosymptomatic), and true, severe dysuria (rare). However, "dysuria" in the broad sense did not affect the patients' quality of life, and is a reminder of the absolute necessity of meticulous compliance with the correct surgical techniques. CONCLUSION: Treatment of urinary incontinence by TVT is a reliable, mini-invasive, reproducible technique, almost suitable for outpatients, with no serious complications; it is inexpensive and very successful, including in complicated cases such as sphincter deficiency. All the recent data confirms, with this 5-year follow-up, that the TVT procedure is comparable to the previously gold standard, the Burch colposuspension.


Assuntos
Slings Suburetrais , Incontinência Urinária por Estresse/cirurgia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Humanos , Pessoa de Meia-Idade , Satisfação do Paciente , Estudos Prospectivos , Recidiva , Slings Suburetrais/efeitos adversos , Resultado do Tratamento
11.
Gynecol Obstet Fertil ; 34(7-8): 615-8, 2006.
Artigo em Francês | MEDLINE | ID: mdl-16777462

RESUMO

Bartholinitis is the most common infectious vulvar disease and develops in approximately 2% of all women. The choice concerning treatment may be uneasy between medical or surgical modalities, and we have to be cautious because of the risk of severe complications associated with the procedure. We report two cases: one case of sepsis and the other one of bacterial cellulitis after Bartholin's duct abscess marsupialization. In the light of epidemiological and bacteriological date referring to Bartholinitis, we recommend a safe and effective management (particularly the use of broad-spectrum antibiotics) that we will describe.


Assuntos
Abscesso/cirurgia , Glândulas Vestibulares Maiores , Complicações Pós-Operatórias/microbiologia , Doenças da Vulva/cirurgia , Antibacterianos/uso terapêutico , Bacteriemia/tratamento farmacológico , Bacteriemia/microbiologia , Celulite (Flegmão)/tratamento farmacológico , Celulite (Flegmão)/microbiologia , Enterobacteriaceae/isolamento & purificação , Infecções por Enterobacteriaceae/tratamento farmacológico , Infecções por Enterobacteriaceae/etiologia , Feminino , Humanos , Pessoa de Meia-Idade , Doenças da Vulva/microbiologia
12.
J Gynecol Obstet Biol Reprod (Paris) ; 35(5 Pt 1): 504-12, 2006 Sep.
Artigo em Francês | MEDLINE | ID: mdl-16940921

RESUMO

Colorectal carcinoma during pregnancy is very rare. Prognosis is severe because of the advanced stage due to delay in diagnosis and the aggressiveness of this widespread metastatic disease. We report the case of colon metaststic adenocarcinoma during a twin pregnancy with a good outcome. In the light of epidemiology, pathogeny and immunology, the diagnostic challenge for clinicians is distinguishing pregnancy symptoms from the warning signs of colorectal cancer and, we describe recommended medical and surgical management.


Assuntos
Adenocarcinoma/diagnóstico , Neoplasias Colorretais/diagnóstico , Complicações Neoplásicas na Gravidez/diagnóstico , Adenocarcinoma/terapia , Adulto , Quimioterapia Adjuvante , Neoplasias Colorretais/terapia , Feminino , Humanos , Neoplasias Peritoneais/diagnóstico , Neoplasias Peritoneais/secundário , Neoplasias Peritoneais/terapia , Gravidez , Complicações Neoplásicas na Gravidez/terapia
13.
Eur J Obstet Gynecol Reprod Biol ; 205: 7-10, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27552172

RESUMO

OBJECTIVE: Uterine infertility (UI), which can be caused by a variety of congenital or acquired factors, affects several thousand women in Europe. Uterus transplantation (UTx), at the current stage of research, offers hope for these women to be both the biological mother and the carrier of their child. However, the indications of UTx still need to be defined. The main aim of the study was to describe the different etiologies of UI and other data as marital and parental status from women requesting UTx who contacted us in the framework of a UTx clinical trial. Secondarily, we discussed the potential indications of UTx and their feasibility. STUDY DESIGN: This is an observational study. RESULTS: Of a total of 139 patients with UI, 105 patients (75.5%) had uterine agenesis, making it the leading cause of UI in this sample. Among the patients with uterine agenesis, 25% had a solitary kidney and 44.7% had undergone vaginal reconstruction. Peripartum hysterectomy, hysterectomy for cancer, and hysterectomy for benign pathologies accounted for 9.4%, 7.2% and 5% of cases, respectively. Less common causes of UI included complete androgen insensitivity syndrome (2.2% of patients) and prenatal diethylstilbestrol exposure (0.7%). Approximately 14% of the women already had at least one child and 66% were in a couple living together for at least 2 years. CONCLUSION: UTx is still under evaluation and further research is under way. Nulliparous patients with no major medical or surgical history and with normal ovarian function, who meet the legal criteria for medically assisted reproduction, represent the best indications for UTx at this stage of its development.


Assuntos
Infertilidade Feminina/cirurgia , Seleção de Pacientes , Anormalidades Urogenitais/cirurgia , Útero/anormalidades , Útero/transplante , Adulto , Feminino , França , Humanos , Infertilidade Feminina/etiologia , Estado Civil , Resultado do Tratamento , Anormalidades Urogenitais/complicações , Útero/cirurgia
14.
Biochim Biophys Acta ; 800(1): 28-32, 1984 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-6743682

RESUMO

Freeze-fracture electron microscopy of calf lens nuclear cytoplasm undergoing a cold cataract opacification shows the formation of domains within the bulk cytoplasm. The size distribution of these domains (from a few tens of nanometers to a few micrometers) is compatible with previous size evaluations obtained from light scattering experiments for the 'large scattering elements' responsible for cold cataract opacification. In addition, these domains appear to be devoid of crystallins of higher molecular weight and enriched in low-molecular-weight species.


Assuntos
Catarata/patologia , Cristalinas/análise , Cristalino/ultraestrutura , Animais , Bovinos , Núcleo Celular/ultraestrutura , Citoplasma/ultraestrutura , Técnica de Fratura por Congelamento , Microscopia Eletrônica
15.
J Mol Biol ; 205(4): 713-28, 1989 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-2926823

RESUMO

Short range, liquid-like order of the crystallin proteins accounts for eye lens transparency. The relationship between structural and thermodynamic properties of eye lens was further investigated using osmotic pressure and small-angle X-ray scattering measurements of calf lens alpha-crystallins. The consistency of both data sets confirms that the macroscopic thermodynamic properties are determined by the structural properties accessible to X-ray scattering. In addition, the experimental data were correctly accounted for using a model developed in liquid-state physics: the rescaled mean spherical approximation combined with a Verwey-Overbeek potential. This model provides as best fit parameters the excluded volume, the charge and the diameter of an "equivalent" particle that compare well with the corresponding values found in the literature for alpha-crystallins. As a result, transparency may now be expressed as a function of a few structural parameters, the role of which is discussed. The approach presented here may be extended to studies of the thermodynamic-structural relationships of other protein solutions.


Assuntos
Cristalinas , Cristalino , Animais , Bovinos , Modelos Moleculares , Modelos Teóricos , Pressão Osmótica , Termodinâmica , Difração de Raios X
16.
J Mol Biol ; 192(4): 711-24, 1986 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-3586011

RESUMO

Calf lens alpha-crystallins are polydisperse globular particles made of a large number of two types of subunits, A and B, both of molecular weight congruent to 20,000. alpha-Crystallin populations consisting on average of 40 subunits or more were subjected to various changes in pH, ionic strength, temperature and urea concentration. Modifications in quaternary structure induced by variation of these physicochemical parameters were followed by means of X-ray and quasi-elastic light-scattering and quantified in terms of weight average molecular weight (M), radius of gyration (Rg) and hydrodynamic radius (Rh). High-pressure liquid chromatography was used as a control of polydispersity. Increasing the pH, decreasing the ionic strength and incubating at temperatures from 20 degrees C to 45 degrees C all resulted in the formation of particles of decreasing M, Rg and Rh values. These effects are cumulative. All monomodal alpha-crystallin populations encountered in this study, which covers a wide range of sizes and molecular weights, may be accounted for by a three-layer model with partial filling up of the layers. Applying basic principles of symmetry and postulating specific contacts between protein subunits to construct this three-layer model leads to tetrahedral symmetry, with 12, 24 and 24 sites in the first, second and third layers, respectively. Variations in probabilities of site occupancy account for both the observed quaternary structure modifications and the intrinsic polydispersity of alpha-crystallins


Assuntos
Cristalinas , Cristalino/análise , Animais , Bovinos , Cromatografia Líquida de Alta Pressão , Concentração de Íons de Hidrogênio , Luz , Substâncias Macromoleculares , Modelos Moleculares , Espalhamento de Radiação , Temperatura , Ureia , Raios X
17.
J Mol Biol ; 164(4): 645-50, 1983 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-6842602

RESUMO

The self-assembly of brome mosaic virus capsid has been studied kinetically by means of X-ray and neutron scattering. It appears to be a very fast process: for the concentrations used (5 to 8 mg/ml) the forward scattering reaches 50% of its maximal value in less than one second. Further, the assembly seems to proceed through intermediate states whose nature is still speculative.


Assuntos
Capsídeo/biossíntese , Vírus do Mosaico/metabolismo , Proteínas Virais/biossíntese , Cinética , Nêutrons , Espalhamento de Radiação , Difração de Raios X
18.
Biophys Chem ; 117(3): 217-24, 2005 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-15963625

RESUMO

The relative effectiveness of different anions in crystallizing proteins follows a reversed Hofmeister sequence for pHpI. The phenomenon has been known almost since Hofmeister's original work but it has not been understood. It is here given a theoretical explanation. Classical electrolyte and double layer theory deals only with electrostatic forces acting between ions and proteins. Hydration and hydration interactions are dealt with usually only in terms of assumed hard core models. But there are, at and above biological salt concentrations, other non-electrostatic (NES) ion-specific forces acting that are ignored in such modeling. Such electrodynamic fluctuation forces are also responsible for ion-specific hydration. These missing forces are variously comprehended under familiar but generally unquantified terms, typically, hydration, hydrogen bonding, pi-electron-cation interactions, dipole-dipole, dipole-induced dipole and induced dipole-induced dipole forces and so on. The many important body electrodynamic fluctuation force contributions are accessible from extensions of Lifshitz theory from which, with relevant dielectric susceptibility data on solutions as a function of frequency, the forces can be extracted quantitatively, at least in principle. The classical theories of colloid science that miss such contributions do not account for a whole variety of ion-specific phenomena. Numerical results that include these non-electrostatic forces are given here for model calculations of the force between two model charge-regulated hen-egg-white protein surfaces. The surfaces are chosen to carry the same charge groups and charge density as the protein. What emerges is that for pHpI (where anions are co-ions) the forces increase in the order NaCl

Assuntos
Proteínas/química , Fenômenos Biomecânicos , Concentração de Íons de Hidrogênio , Íons/química , Modelos Biológicos , Soluções
19.
Biochimie ; 66(1): 49-58, 1984 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-6231961

RESUMO

In this paper, we describe an efficient procedure for the purification of yeast phosphofructokinase. This procedure eliminates any time delay and enables to obtain an enzyme with minimum proteolytic alterations. The molecular weights of the oligomeric enzyme and of its constitutive subunits were both evaluated by means of several independent methods. However, the accuracy of each measurement was not sufficient to discriminate between an hexameric and an octameric structure of the enzyme oligomer. On the other hand, crosslinking experiments demonstrated the octameric structure of yeast phosphofructokinase. Obviously, some methods of molecular weight determination have led to erroneous results. In particular, our experiments show that the reliability of molecular weight determinations performed by gel filtration of native proteins must be considered with caution.


Assuntos
Fosfofrutoquinase-1/isolamento & purificação , Saccharomyces cerevisiae/enzimologia , Reagentes de Ligações Cruzadas/farmacologia , Substâncias Macromoleculares , Peso Molecular , Fosfofrutoquinase-1/metabolismo , Conformação Proteica , Espalhamento de Radiação , Raios X
20.
Biophys Chem ; 89(1): 65-76, 2001 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-11246746

RESUMO

Among lens crystallins, gamma-crystallins are particularly sensitive to oxidation, because of their high amount of Cys and Met residues. They have the reputation to induce, upon ageing, lens structural modifications leading to opacities. A combination of small angle X-ray scattering and chromatography was used to study the oxidation of gamma-crystallins. At pH 7.0, all the gamma-crystallins under study were checked to have the same structure in solution. Under gentle oxidation conditions at pH 8.0, human gammaS (hgammaS) and bovine gammaS (bgammaS) formed disulfide-linked dimers, whereas the other bgamma-crystallins did not. Cys20 was shown to be responsible for dimer formation since the C20S mutant only formed monomers. The hgammaS dimers were stable for weeks and did not form higher oligomers. In contrast, monomeric gammaS-crystallins freshly prepared at pH 8.0, and submitted to more drastic oxidation by X-ray induced free radicals, were rapidly transformed into higher oligomers. So, only extensive oxidation causing partial unfolding could be detrimental to the lens and linked to cataract formation. The gammaS-crystallins lack the temperature-induced opacification observed with the other gamma-crystallins and known as cold cataract. The oxidation-induced associative behaviour and cold cataract are therefore demonstrated to be uncoupled.


Assuntos
Cristalinas/química , Cristalino/química , Sequência de Aminoácidos , Animais , Bovinos , Temperatura Baixa , Dimerização , Humanos , Concentração de Íons de Hidrogênio , Dados de Sequência Molecular , Oxirredução , Conformação Proteica , Espalhamento de Radiação , Homologia de Sequência de Aminoácidos , Espectrometria de Massas por Ionização por Electrospray
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