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1.
BMC Cancer ; 22(1): 956, 2022 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-36068484

RESUMO

Tregs are able of suppressing tumor-specific effector cells, such as lymphocytes CD8+, CD4+ and Natural Killer cells. Different drugs, especially different schedules of administration, like metronomic chemotherapy (mCHT), seem to be able to increase anticancer immunity, by acting on downregulation of Tregs. Most of the data available regarding the immunomodulating effect of mCHT have been obtained with Cyclophosphamide (CTX). Aim of the present study was to explore the effects of mVRL and mCAPE administration, alone or in combination, on T cells. Observation of 13 metastatic breast cancer patients lasted controlling for 56 days, where Treg frequencies and function, spontaneous anti-tumor T-cell responses were monitored, as well as the clinical outcome. No depletion in Treg absolute numbers, or percentage of T lymphocytes, was observed. Only in 5 patients, a modest and transient depletion of Tregs was observed during the first 14 days of treatment. To better describe the effect on Tregs, we subsequently looked at the variations in Memory, Naïve and Activated Treg subpopulations: we observed a trend in reduction for memory Treg (Treg MEM) and an increase for Treg Naïve (Treg NAIVE) and Treg Activated (Treg ACT) components. We finally analyzed the average trend of Treg in the Treg depleted patients and non-depleted ones, without fiding any significant differences. The trend of the Treg MEM appeared different, showing a reduction during the first 14 days, followed by an increase at the levels before treatment at Day 56 in the group of depleted patients and a progressive substantial reduction in the group of non-depleted patients along the entire course of treatment. Opposed to the data known, treatment with mVRL w/o mCAPE did not show any effect on Tregs.


Assuntos
Neoplasias da Mama , Administração Metronômica , Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/patologia , Capecitabina , Feminino , Humanos , Linfócitos T Reguladores , Vinorelbina
2.
Opt Express ; 26(26): 34830-34841, 2018 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-30650900

RESUMO

The quest for extrasolar planets and their characterization as well as studies of fundamental physics on cosmological scales rely on capabilities of high-resolution astronomical spectroscopy. A central requirement is a precise wavelength calibration of astronomical spectrographs allowing for extraction of subtle wavelength shifts from the spectra of stars and quasars. Here, we present an all-fiber, 400 nm wide near-infrared frequency comb based on electro-optic modulation with 14.5 GHz comb line spacing. Tests on the high-resolution, near-infrared spectrometer GIANO-B show a photon-noise limited calibration precision of < 10 cms as required for Earth-like planet detection. Moreover, the presented comb provides detailed insight into particularities of the spectrograph such as detector inhomogeneities and differential spectrograph drifts. The system is validated in on-sky observations of a radial velocity standard star (HD221354) and telluric atmospheric absorption features. The advantages of the system include simplicity, robustness and turn-key operation, features that are valuable at the observation sites.

3.
Nature ; 464(7287): 384-7, 2010 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-20237564

RESUMO

Of the over 400 known exoplanets, there are about 70 planets that transit their central star, a situation that permits the derivation of their basic parameters and facilitates investigations of their atmospheres. Some short-period planets, including the first terrestrial exoplanet (CoRoT-7b), have been discovered using a space mission designed to find smaller and more distant planets than can be seen from the ground. Here we report transit observations of CoRoT-9b, which orbits with a period of 95.274 days on a low eccentricity of 0.11 +/- 0.04 around a solar-like star. Its periastron distance of 0.36 astronomical units is by far the largest of all transiting planets, yielding a 'temperate' photospheric temperature estimated to be between 250 and 430 K. Unlike previously known transiting planets, the present size of CoRoT-9b should not have been affected by tidal heat dissipation processes. Indeed, the planet is found to be well described by standard evolution models with an inferred interior composition consistent with that of Jupiter and Saturn.

5.
Nature ; 460(7259): 1098-100, 2009 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-19713926

RESUMO

The 'hot Jupiters' that abound in lists of known extrasolar planets are thought to have formed far from their host stars, but migrate inwards through interactions with the proto-planetary disk from which they were born, or by an alternative mechanism such as planet-planet scattering. The hot Jupiters closest to their parent stars, at orbital distances of only approximately 0.02 astronomical units, have strong tidal interactions, and systems such as OGLE-TR-56 have been suggested as tests of tidal dissipation theory. Here we report the discovery of planet WASP-18b with an orbital period of 0.94 days and a mass of ten Jupiter masses (10 M(Jup)), resulting in a tidal interaction an order of magnitude stronger than that of planet OGLE-TR-56b. Under the assumption that the tidal-dissipation parameter Q of the host star is of the order of 10(6), as measured for Solar System bodies and binary stars and as often applied to extrasolar planets, WASP-18b will be spiralling inwards on a timescale less than a thousandth that of the lifetime of its host star. Therefore either WASP-18 is in a rare, exceptionally short-lived state, or the tidal dissipation in this system (and possibly other hot-Jupiter systems) must be much weaker than in the Solar System.

7.
G Chir ; 35(3-4): 75-7, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24841683

RESUMO

OBJECTIVE: Multiple and bilateral ovarian dermoid cysts constitute a very unusual report. We report an rare case of a woman with three ovarian dermoid cyst, two localized in the same ovary, detected by US examination and removed by laparoscopy. CASE REPORT: A patient aged 29 years, para 0, gravida 0, was referred to our hospital with pain of the right adnexal region. Gynaecological examination showed an antiverted uterus with normal volume; on the right side a mobile mass approximately 7 cms in diameter was palpable, moreover the left ovary was normal. Ultrasound examination showed a normal uterus. The right ovary presented two complex masses of 7 and 3 cm in diameter, respectively; moreover, the left ovary showed a hyperechogenic complex mass of 3 cm in diameter. The ultrasound pattern was compatible with bilateral ovarian dermoid cysts. On laparoscopy abdominal cavity and uterus were normal, while the right ovary presented two masses and the left ovary a small mass which were enucleated and removed. The patient had an uncomplicated postoperative recovery and was discharged two day after laparoscopy. Pathologic examination confirmed the diagnosis of ovarian dermoid cysts. A one year follow-up showed no evidence of recurrence. CONCLUSION: The case reported shows that exceptionally multiple and bilateral dermoid cysts may be detected underlining the importance of an accurate preoperative diagnostic imaging. Some recurrence of ovarian dermoid cysts may be due to undiagnosed small dermoid cists during preoperative imaging and/or surgical exploration.


Assuntos
Cisto Dermoide/diagnóstico por imagem , Cisto Dermoide/cirurgia , Laparoscopia , Neoplasias Ovarianas/diagnóstico por imagem , Neoplasias Ovarianas/cirurgia , Adulto , Cisto Dermoide/patologia , Feminino , Humanos , Neoplasias Ovarianas/patologia , Doenças Raras , Resultado do Tratamento , Ultrassonografia
8.
Sci Rep ; 13(1): 12255, 2023 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-37507480

RESUMO

Nowadays, treatment of metastatic breast cancer (MBC) has been enriched with novel therapeutical strategies. Metronomic chemotherapy (mCHT) is a continuous and frequent administration of chemotherapy at a lower dose and so whit less toxicity. Thus, this strategy could be attractive for elderly MBC patients. Aim of this analysis is to provide insights into mCHT's activity in a real-life setting of elderly MBC patients. Data of patients ≥ 75 years old included in VICTOR-6 study were analyzed. VICTOR-6 is a multicentre, Italian, retrospective study, which collected data on mCHT in MBC patients treated between 2011 and 2016. A total of 112 patients were included. At the beginning of mCHT, median age was 81 years (75-98) and in 33% of the patients mCHT was the first line choice. Overall Response Rate (ORR) and Disease Control Rate (DCR) were 27.9% and 79.3%, respectively. Median PFS ranged between 7.6 and 9.1 months, OS between 14.1 and 18.5 months. The most relevant toxicity was the hematological one (24.1%); severe toxicity (grade 3-4) ranged from 0.9% for skin toxicity up to 8% for hematologic one. This is a large study about mCHT in elderly MBC patients, providing insights to be further investigated in this subgroup of frail patients.


Assuntos
Neoplasias da Mama , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Administração Metronômica , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/patologia , Estudos Retrospectivos
9.
Sci Rep ; 12(1): 4728, 2022 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-35304876

RESUMO

The evolution of forearc and backarc domains is usually treated separately, as they are separated by a volcanic arc. We analyse their spatial and temporal relationships in the Tyrrhenian subduction system, using seismic profiles and numerical modelling. A volcanic arc, which included the Marsili volcano, was involved in arc-rifting during the Pliocene. This process led to the formation of an oceanic backarc basin (~ 1.8 Ma) to the west of the Marsili volcano. The eastern region corresponded to the forearc domain, floored by serpentinised mantle. Here, a new volcanic arc formed at ~ 1 Ma, marking the onset of the forearc-rifting. This work highlights that fluids and melts induce weakening of the volcanic arc region and drive the arc-rifting that led to the backarc basin formation. Later, the slab rollback causes the trench-ward migration of volcanism that led to the forearc- rifting under the control of fluids released from the downgoing plate.

10.
J Nanosci Nanotechnol ; 11(10): 8754-62, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22400255

RESUMO

Titanium is the most widely used material in orthopaedic and dental implantoprosthesis due to its superior physical properties and enhanced biocompatibility due to the spontaneous formation of a passivating layer of titanium oxides which, however, does not form good chemical bonds with bone and tends to brake exposing bulk titanium to harsh body fluids releasing titanium particles which may prime an inflammation response and a fibrotic tissue production. In order to avoid these possible problems and to enhance the biocompatibility of titanium implants, modifications of titanium surfaces by many different materials as hydroxyapatite, titanium nitride, titanium oxide and titanium carbide have been proposed. The latter is shown to be an efficient protection for the titanium implant in the harsh conditions of biological tissues and, compared to untreated titanium, acting like an osteoblast stimulation factor increasing in vitro production of proteins involved in osteogenesis. These results were confirmed by in vivo experiments in rabbits: implants covered by the titanium carbide (TiC) layer were faster and better osseointegrated than untreated titanium implants. The TiC layer was deposited by a Pulsed Laser Deposition (PLD) device which allowed only one deposition per cycle, shown to be unsuitable for industrial applications. Therefore the main objective of the present work was to replace PLD process with an Ion Plating Plasma Assisted (IPPA) deposition process, which is suitable for industrial upgrading. By this technique, nanostructured TiOx-TiCy-C has been deposited on titanium after sandblasting with 120 micron zirconia spheres. XPS analyses revealed the presence of about 33% carbon (50% of which is present as free carbon), 39% oxygen and 28% titanium (37% of which is bound to carbon to form TiC and 63% is bound to oxygen to form non stoichiometric oxides). Surface mechanical response of as-deposited coatings has been performed by nanoindentation techniques. Focused Ion Beam micrographs showed bigger differences on the obtained nanostructure compared to the PLD coating structure; in vitro tests confirm for IPPA produced coatings an improvement in stimulating osteoblasts to produce mRNA's of proteins involved in the ossification process, this latter case they resulted to be faster and more efficient. The proposed treatement is expected to improve the good results obtained by PLD, in vivo as well.


Assuntos
Osso e Ossos/citologia , Materiais Revestidos Biocompatíveis/química , Titânio/química , Animais , Osso e Ossos/efeitos dos fármacos , Osso e Ossos/metabolismo , Linhagem Celular , Materiais Revestidos Biocompatíveis/farmacologia , Durapatita/química , Dureza , Humanos , Íons/metabolismo , Lasers , Microesferas , Nanoestruturas/química , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Osteoblastos/metabolismo , Osteogênese/efeitos dos fármacos , Próteses e Implantes , Coelhos , Propriedades de Superfície , Titânio/metabolismo , Titânio/farmacologia , Zircônio/química
11.
ESMO Open ; 6(3): 100124, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33940346

RESUMO

BACKGROUND: The role of tumor mutational burden (TMB) is still debated for selecting advanced non-oncogene addicted non-small-cell lung cancer (NSCLC) patients who might benefit from immune checkpoint inhibitors (ICIs). Of note, TMB failed to predict a benefit in overall survival (OS) among such patients. MATERIALS AND METHODS: The purpose of this meta-analysis was to compare efficacy outcomes among first-line immune-oncology (IO) agents versus standard platinum-based chemotherapy (CT) within two subgroups (TMB-low and TMB-high on either tissue or blood). We collected hazard ratios (HRs) to evaluate the association for progression-free survival (PFS) and OS, with the relative 95% confidence intervals (CIs). Risk ratios (RRs) were used as an association measure for objective response rate (ORR). RESULTS: Eight different cohorts of five randomized controlled phase III studies (3848 patients) were analyzed. In TMB-high patients, IO agents were associated with improved ORR (RRs 1.37, 95% CI 1.13-1.66), PFS (HR 0.69, 95% CI 0.61-0.79) and OS (HR 0.67, 95% CI 0.59-0.77) when compared with CT, thus suggesting a possible predictive role of high TMB for IO regimens. In TMB-low patients, the IO strategy did not lead to any significant benefit in survival and activity, whereas the pooled results of both ORR and PFS were intriguingly associated with a statistical significance in favor of CT. CONCLUSIONS: This meta-analysis resulted in a proven benefit in OS in favor of IO agents in the TMB-high population. Although more prospective data are warranted, we postulated the hypothesis that monitoring TMB, in addition to the existing programmed death-ligand 1 (PD-L1) expression level, could represent the preferable option for future clinical research in the first-line management of advanced non-oncogene addicted NSCLC patients.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Carcinoma Pulmonar de Células não Pequenas/genética , Ensaios Clínicos Fase III como Assunto , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/genética , Prognóstico , Estudos Prospectivos , Ensaios Clínicos Controlados Aleatórios como Assunto
12.
J Cell Biol ; 28(3): 505-25, 1966 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-4163862

RESUMO

FROM OBSERVATIONS OF FLUORESCENT ANTIBODY STAINING AND ANTIBODY STAINING IN ELECTRON MICROSCOPY, EVIDENCE IS PRESENTED FOR THE FOLLOWING: (a) Direct contact of the actin and myosin filaments occurs at all stages of contraction. This results in inhibition of antibody staining of the H-meromyosin portion of the myosin molecule in the region of overlap of the thin and thick filaments. (b) Small structural changes occur in the thick filaments during contraction. This leads to exposure of antigenic sites of the L-meromyosin portion of the myosin molecule. The accessibility of these antigenic sites is dependent upon the sarcomere length. (c) The M line is composed of a protein which is weakly bound to the center of the thick filament and is not actin, myosin, or tropomyosin. (d) Tropomyosin as well as actin is present in the I band. (e) If actin or tropomyosin is present in the Z line, it is masked and unavailable for staining with antibody.


Assuntos
Miofibrilas/anatomia & histologia , Animais , Antígenos , Dactinomicina , Imunofluorescência , Microscopia Eletrônica , Proteínas Musculares , Aves Domésticas , Coloração e Rotulagem
13.
J Cell Biol ; 48(2): 340-7, 1971 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-4101522

RESUMO

The M band can be extracted from fibrils suspended in 5 mM Tris buffer, pH 8.0, for 15 min. The M band is completely removed only from fibrils of sarcomere lengths greater than 2.1 micro. Extraction does not alter the fluorescent antimyosin staining pattern of the A band, thus providing strong evidence that no alteration of the structural integrity of the thick filament has occurred. Fluorescent antibody staining of the M band of unextracted fibrils can be prevented specifically by absorbing the fluorescent antibody with extracted M band material prior to staining. This verifies the specificity of the extraction procedure.


Assuntos
Imunofluorescência , Proteínas Musculares/isolamento & purificação , Miofibrilas/análise , Actinas , Animais , Soluções Tampão , Galinhas , Ácido Edético , Soros Imunes , Microscopia Eletrônica , Microscopia de Fluorescência , Microscopia de Contraste de Fase , Miosinas , Cloreto de Potássio , Coloração e Rotulagem , Fatores de Tempo
14.
J Cell Biol ; 52(2): 255-60, 1972 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-4550711

RESUMO

The subunit organization of the myosin filament of chicken striated muscle has been observed directly in cross-sections in electron microscopy. The organization consists of three centrally located and nine peripherally located subunits in a close-packed arrangement. This arrangement is that predicted by a previously derived model for the detailed molecular organization of the myosin filament (Pepe, 1966 a, 1967 a, 1971). Each subunit measures approximately 30 A in diameter and the center-to-center distance is approximately 37 A. If these measurements are considered to be on the high side, then they indicate that each subunit represents one myosin molecule. However, it is not possible to determine unequivocally whether one or two myosin molecules per subunit are present on the basis of this work.


Assuntos
Proteínas Musculares , Músculos/citologia , Animais , Galinhas , Glicerol , Técnicas Histológicas , Masculino , Glândulas Mamárias Animais/citologia , Microscopia Eletrônica , Modelos Estruturais , Miosinas
15.
J Cell Biol ; 85(1): 33-41, 1980 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-6988442

RESUMO

The specific contributions of this work may be summarized as follows: (a) No hybridization of uterine and skeletal myosin occurs at pH 6.0 although previous studies have shown that hybridization does occur at pH 6.5 (B. Kaminer et al. 1976. J. Mol. Biol. 100:379-386) or 7.0 (T. Pollard. 1975. J. Cell Biol. 67:93-104) (b) Hybridization of uterine and skeletal light meromyosins (LMM) occurs at pH 7.0 but not at pH 6.0, which is analogous to the hybridization of myosins. (c) In hybridized paracrystals there is a uniform distribution of both uterine and skeletal LMM molecules because all the paracrystals have only one axial repeat pattern. This makes it highly likely that in hybridized filaments the two myosins are also uniformly distributed throughout the filaments. (d) The 14-nm repeat of white bands observed in paracrystals of uterine LMM formed at pH 6.0, compared with the 14-nm repeat of dark bands observed with skeletal LMM under the same conditions, probably reflects differences in surface charge density along the different LMM molecules.


Assuntos
Citoesqueleto/análise , Músculos/análise , Miométrio/análise , Subfragmentos de Miosina , Miosinas , Útero/análise , Animais , Fenômenos Químicos , Química , Galinhas , Cristalização , Citoesqueleto/ultraestrutura , Feminino , Concentração de Íons de Hidrogênio , Coelhos
16.
J Cell Biol ; 37(2): 445-61, 1968 May.
Artigo em Inglês | MEDLINE | ID: mdl-5656401

RESUMO

Rhodnius prolixus, a South American insect, molts five times in its development to an adult after emerging from the egg. Each molting cycle is triggered with a blood-meal. The ventral intersegmental abdominal muscles of Rhodnius develop during each molting cycle and are functional at molting. The fine structure of these fully developed muscles from fourth stage larval insects is studied. They have the characteristic structure of slow muscles. They have multiple motor nerve endings, and the myofibrils are poorly defined in cross-section. Longitudinal sections show long sarcomeres (8-10 micro), irregular Z-lines, and no apparent H zones. No M line is seen. Transverse sections through the A-band region show that each hexagonally arranged thick filament is surrounded by 12 thin filaments. Two thin filaments are shared by two neighboring thick filaments. The ratio of thin to thick filaments is 6:1. This structure is related to that found in vertebrate skeletal muscle and insect flight muscle.


Assuntos
Insetos/fisiologia , Metamorfose Biológica/fisiologia , Músculos/citologia , Abdome/citologia , Animais , Microscopia Eletrônica , Músculos/inervação , Junção Neuromuscular/citologia
17.
J Cell Biol ; 37(2): 462-81, 1968 May.
Artigo em Inglês | MEDLINE | ID: mdl-5656402

RESUMO

The development of the ventral intersegmental abdominal muscles of Rhodnius prolixus is triggered by feeding. The early muscle (1 day after feeding) contains essentially nonstriated fibrils. However, in cross-sections, areas indicating early I bands, Z lines, and A bands can be recognized. Interdigitating thick and thin myofilaments do not assemble into a precise lattice until sometime between 4 and 5 days after feeding. As development continues, the number of fibrils increases, the region corresponding to the Z line increases in density, and the fibrils contain more recognizable striations. The newly formed fibrils broaden as myofilaments are added peripherally. At all stages throughout development, the ratio of thin to thick myofilaments is always 6:1. The formation of fibrils in the abdominal muscles of Rhodnius is different from that in chick embryo skeletal muscle. The major differences are that at all stages in Rhodnius there are (1) a constant ratio of thin to thick myofilaments, and (2) detectable Z-line material. Other findings in Rhodnius suggest (1) that fusion of mononucleated cells with the multinucleated muscle cell occurs, (2) that microtubules develop in the tendon cell concomitantly with development of myofibrils in the associated muscle cell, and (3) that filaments 55A in diameter aggregate into microtubules.


Assuntos
Insetos/fisiologia , Metamorfose Biológica/fisiologia , Músculos/citologia , Abdome/citologia , Animais , Núcleo Celular , Microscopia Eletrônica , Mitose , Miofibrilas , Sistema Nervoso/citologia
18.
J Cell Biol ; 94(3): 565-73, 1982 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-7130272

RESUMO

The conclusions arrived at as a result of this work can be summarized as follows: (a) We have found that there is an 85,000-dalton protein, which we have called 85K amorphin, associated with the Z-band of chicken pectoralis muscle myofibrils. We have isolated and purified this protein. It is not a structural component of the Z-filaments since it can be extracted completely without extraction of the Z-filaments. Extraction of 85K amorphin results in loss of specific staining of the Z-band with fluorescence specific anti-85K amorphin. (b) We have found that alpha-actinin is the structural component of the Z-filaments, since extraction of alpha-actinin is accompanied by loss of the Z-filament structure.


Assuntos
Actinina/metabolismo , Proteínas Musculares/isolamento & purificação , Proteínas Musculares/metabolismo , Músculos/ultraestrutura , Actinina/imunologia , Aminoácidos/análise , Animais , Especificidade de Anticorpos , Galinhas , Peso Molecular , Proteínas Musculares/imunologia , Retículo Sarcoplasmático/análise
19.
J Cell Biol ; 55(3): 681-95, 1972 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-4632583

RESUMO

M band protein can be specifically extracted from fresh chicken breast muscle myofibrils suspended in 5 mM Tris-HCl pH 8.0. During discontinuous polyacrylamide gel electrophoresis the isolated protein separates into three bands which can be identified as two separate components (A, B) and a complex of the two. When partially purified fractions of the separated components are combined, an increase in the intensity of the band containing the complex can be shown. The polypeptide chain weights of the two components are 100,000 (A) and 40,000 (B) daltons as estimated by sodium dodecyl sulfate- (SDS-) polyacrylamide gel electrophoresis. Antibody prepared against total M band protein stains only the M band of the myofibril and is completely absorbed by M band protein. M band protein also absorbs the M band staining specifically from antibody which stains both I and M bands. Immunodiffusion data indicate that anti-M band is a mixture of two specific antibodies, one against each component.


Assuntos
Proteínas Musculares/isolamento & purificação , Músculos/análise , Animais , Reações Antígeno-Anticorpo , Precipitação Química , Galinhas , Eletroforese Descontínua , Imunofluorescência , Concentração de Íons de Hidrogênio , Imunodifusão , Substâncias Macromoleculares , Masculino , Peso Molecular , Miofibrilas/análise , Coelhos/imunologia , Dodecilsulfato de Sódio , Ultracentrifugação
20.
J Cell Biol ; 74(1): 136-52, 1977 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-326798

RESUMO

STUDIES OF PARACRYSTAL FORMATION BY COLUMN PURIFIED LIGHT MEROMYOSIN (LMM) PREPARED IN A VARIETY OF WAYS LED TO THE FOLLOWING CONCLUSIONS: (a) different portions of the myosin rod may be coded for different stagger relationships. This was concluded from observations that paracrystals with different axial repeat periodicities could be obtained either with LMM framents of different lengths prepared with the same enzyme, or with LMM fragments of identical lengths but prepared with different enzymes. (b) Paracrystals with a 14-nm axial repeat periodicity are most likely formed by the aggregation of sheets with a 44-nm axial repeat within the sheets which are staggered by 14 nm. All of the axial repeat patterns expected from one sheet or aggregates of more than one sheet, on this basis, were observed in the same electron micrograph. (c) C-protein binding probably occurs preferentially to LMM molecules related in some specific way. This was concluded from the observation that the same axial repeat pattern was obtained in paracrystals formed from different LMM preparations in the presence of C-protein, regardless of differences in the axial repeat obtained in the absence of C-protein. (d) Nucleic acid is responsible for the 43-nm axial repeat patterns observed in paracrystals formed by the ethanol-resistant fraction of LMM. In the absence of nuclei acid, paracrystals with a 14nm axial repeat are obtained. (e) The 43-nm axial repeat pattern observed with the ethanol-resistant fraction of LMM is different for LMM preparations obtained by trypsin and papain digestions.


Assuntos
Subfragmentos de Miosina , Cristalização , Eletroforese em Gel de Poliacrilamida , Peso Molecular , Proteínas Musculares/metabolismo , Subfragmentos de Miosina/isolamento & purificação , Subfragmentos de Miosina/metabolismo , Papaína , Conformação Proteica , RNA , Tripsina
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