RESUMO
To investigate the effects of added molecular heterogeneity on the hysteretic features of liquid-glass-liquid transition, we studied acetaminophen, sulfathiazole, and three of their mixtures by calorimetry, and determined the T(g) and the fictive temperature, T(f), from changes in the enthalpy and entropy on the cooling and heating paths, as well as the non-exponential parameter, ß(cal). We find that, (i) T(f) for cooling is within 1-3 K of T(f) for heating and both are close to T(g), (ii) the closed loop entropy change in the liquid-glass-liquid range is negligibly small, (iii) T(g) and T(f) increase on increasing sulfathiazole in the mixture, (iv) ß(cal) first slightly increases when the second component is added and then decreases, and (v) ageing causes deviations from a non-exponential, nonlinear behavior of the glass. In terms of fluctuations in a potential energy landscape, adding a solute heterogeneity would shift the state point to another part of the landscape with a different distribution of barrier heights and a different number of minima accessible to the state point. Part of the change in ß(cal) is attributed to hydrogen-bond formation between the two components. Ageing changes the relaxation times distribution, more at short relaxation times than at long relaxation times, and multiplicity of relaxation modes implied by ß(cal) < 1 indicates that each mode contributing to the enthalpy has its own T(g) or T(f). ß(cal) differs from ß(age) determined from isothermal ageing, and the distribution parameter of α-relaxation times would differ from both ß(cal) and ß(age).
RESUMO
Certain distributions of relaxation times can be described in terms of a non-exponential response parameter, ß, of value between 0 and 1. Both ß and the relaxation time, τ0, of a material depend upon the probe used for studying its dynamics and the value of ß is qualitatively related to the non-Arrhenius variation of viscosity and τ0. A solute adds to the diversity of an intermolecular environment and is therefore expected to reduce ß, i.e., to increase the distribution and to change τ0. We argue that the calorimetric value ß(cal) determined from the specific heat [Cp = T(dS∕dT)p] data is a more appropriate measure of the distribution of relaxation times arising from configurational fluctuations than ß determined from other properties, and report a study of ß(cal) of two sets of binary mixtures, each containing a different molecule of â¼2 nm size. We find that ß(cal) changes monotonically with the composition, i.e., solute molecules modify the nano-scale composition and may increase or decrease τ0, but do not always decrease ß(cal). (Plots of ß(cal) against the composition do not show a minimum.) We also analyze the data from the literature, and find that (i) ß(cal) of an orientationally disordered crystal is less than that of its liquid, (ii) ß(cal) varies with the isomer's nature, and chiral centers in a molecule decrease ß(cal), and (iii) ß(cal) decreases when a sample's thickness is decreased to the nm-scale. After examining the difference between ß(cal) and ß determined from other properties we discuss the consequences of our findings for theories of non-exponential response, and suggest that studies of ß(cal) may be more revealing of structure-freezing than studies of the non-Arrhenius behavior. On the basis of previous reports that ß â 1 for dielectric relaxation of liquids of centiPoise viscosity observed at GHz frequencies, we argue that its molecular mechanism is the same as that of the Johari-Goldstein (JG) relaxation. Its spectrum becomes broader on cooling and its unimodal distribution reversibly changes to a bimodal distribution, each of ß < 1. Kinetic freezing of the slower modes of the bimodal distribution produces a glass. After this bifurcation, the faster, original relaxation persists as a weak JG relaxation at T â T(g), and in the glassy state.
RESUMO
To investigate how non-exponential response could vary under different conditions, we studied the effects of adding 2 nm size polyhedral oligomeric silsesquioxane (POSS) to diglycidyl ether of bisphenol-A, whose molecules have the same terminal (epoxide) dipoles as the tentacle-like side chains attached to the silsesquioxane core of the POSS molecule. Dielectric relaxation spectra show that, on initial addition, the POSS nano-heterogeneity decreases the non-exponential response parameter ß, which is consistent with the dynamic heterogeneity view, but it also decreases the relaxation time τ(m), which is inconsistent with that view. The variations in ß and τ(m) with the composition have a thermal equivalence. Despite the lack of translational diffusion required for dynamic heterogeneity, plastic crystals show non-exponential response and non-Arrhenius dynamics. Measurements of ß and τ(m) seem more appropriate than using probe molecules or modeling nonlinear response data as a sum of linear responses for testing the dynamic heterogeneity view. Data on molecular liquid mixtures is not generally consistent with this view, and adding a solute does not always decrease ß. Studies of mixtures of different size rigid molecules with identical dipolar groups, including polymers, may be useful for comparing the relative effects of temperature and molecular size on ß and τ(m).
Assuntos
Compostos Benzidrílicos/química , Compostos de Epóxi/química , Compostos de Organossilício/química , Espectroscopia Dielétrica , Modelos Moleculares , Estrutura Molecular , Tamanho da Partícula , Propriedades de SuperfícieRESUMO
ABSTRACT Purpose: Patient-reported history of pads per day (PPD) is widely recognized as a fundamental element of decision-making for anti-incontinence procedures. We hypothesize that SUI severity is often underestimated among men with moderate SUI. We sought to compare patient history of incontinence severity versus objective in-office physical examination findings. Materials and Methods: We retrospectively reviewed our single-surgeon male SUI surgical database from 2007-2019. We excluded patients with incomplete preoperative or postoperative data and those who reported either mild or severe SUI, thus having more straightforward surgical counseling. For men reported to have moderate SUI, we determined the frequency of upgrading SUI severity by recording the results of an in-office standing cough test (SCT) using the Male Stress Incontinence Grading Scale (MSIGS). The correlation of MSIGS with sling success rate was calculated. Failure was defined as >1 PPD usage or need for additional incontinence procedure. Results: Among 233 patients with reported moderate SUI (2-3 PPD), 89 (38%) had MSIGS 3-4 on SCT, indicating severe SUI. Among patients with 2-3 PPD preoperatively, sling success rates were significantly higher for patients with MSIGS 0-2 (76/116, 64%) compared to MSIGS 3-4 (6/18, 33%) (p <0.01). Conclusions: Many men with self-reported history of moderate SUI actually present severe SUI observed on SCT. The SCT is a useful tool to stratify moderate SUI patients to more accurately predict sling success.
Assuntos
Humanos , Masculino , Incontinência Urinária por Estresse/cirurgia , Incontinência Urinária por Estresse/diagnóstico , Slings Suburetrais , Prostatectomia , Estudos Retrospectivos , Resultado do Tratamento , TosseRESUMO
The pathogenesis of the anemia which occurs in rats bearing the Shay chloroleukemia (SCL) was investigated. Severe anemia, shown not to result from hemodilution, developed in the terminal stage of the disease. The rapid progression of the anemia suggested that reduced erythropoiesis was of no more than minor importance in the development of this anomaly. No evidence for a major hemolytic event was observed. Data are presented which suggest that hemostatic defects may be primarily responsible for the anemia of SCL. Because of many similarities with the pathogenesis of human myelogenous leukemia, SCL is proposed as a useful model for further studies on interreactions between the leukemic environment and the erythrocyte population.
Assuntos
Anemia/complicações , Leucemia Mieloide/complicações , Animais , Bilirrubina/sangue , Volume Sanguíneo , Eritrócitos , Hematócrito , Ferro/sangue , Leucemia Mieloide/sangue , Leucemia Mieloide/etiologia , Masculino , Ratos , Reticulócitos , Baço/patologia , EsplenectomiaRESUMO
We present two sisters with tetralogy of Fallot and pulmonary valve atresia. Both had identical anatomical findings as seen at cardiac catheterization and angiography and verified operatively, with, in particular, identical bronchial circulation and pulmonary valve structure. The parents are first cousins and there is no history of other affected relatives. We suggest that this is a specific, recessively inherited type of tetralogy of Fallot.
Assuntos
Consanguinidade , Genes Recessivos , Valva Pulmonar/anormalidades , Tetralogia de Fallot/genética , Criança , Feminino , Humanos , MasculinoRESUMO
BACKGROUND: Axonal polyradiculopathy due to cytomegalovirus (CMV) in AIDS has been reported in adults but it is not well documented in children. OBJECTIVE: We describe the elements of diagnosis and the outcome after anti-CMV therapy in a pediatric case. CASE REPORT: A 11-year-old boy with post-transfusional AIDS and low CD4 count (< 50/mm3) suffered from bilateral leg pain and weakness progressing within 15 days to paraplegia and cauda equina syndrome. Electromyography showed pure axonal neuropathy. Examination of the CSF showed increased proteins, low glucose concentration, neutrophilic pleiocytosis and positive detection of CMV by polymerase-chain reaction. The CMV viremia was positive. Treatment with ganciclovir and foscarnet allowed dramatical clinical improvement. Retinitis occurred during the maintenance therapy and was cured after reintroduction of the initial doses of ganciclovir and foscarnet. The child died five months later from a bacterial pneumopathy. CONCLUSIONS: Children with advanced AIDS may benefit from early recognition and treatment of CMV polyradiculopathy. The interactions and cumulated toxicities between anti-CMV and anti-retroviral drugs must be considered. The prognosis remains poor for CMV neuropathy due to the severe immunodepression caused by the HIV infection.
Assuntos
Infecções Oportunistas Relacionadas com a AIDS/diagnóstico , Infecções por Citomegalovirus/complicações , Infecções por Citomegalovirus/diagnóstico , Infecções por HIV/complicações , Polirradiculoneuropatia/virologia , Criança , Infecções por Citomegalovirus/tratamento farmacológico , Quimioterapia Combinada , Foscarnet/administração & dosagem , Foscarnet/uso terapêutico , Ganciclovir/administração & dosagem , Ganciclovir/uso terapêutico , Humanos , MasculinoRESUMO
OBJECTIVES: To report the results from the Brazilian database on multiple sclerosis (MS) and pregnancy. METHODS: Retrospective data from MS patients who became pregnant at any time of their disease were sent to a Brazilian database, using a specific file for this purpose. RESULTS: Data on 128 women (142 pregnancies) from 30 neurologists working in 21 cities in Brazil were collected. Patients' average age at pregnancy was 29.8 years (range 16-42). EDSS at start of pregnancy was 1.5±1.4; and the relapse rate in the year preceding pregnancy was 1.2±1.5. Exposure to medication at any time during pregnancy was high (69.7%): 48.6% to interferon beta; 14.1% to glatiramer acetate; and 7% to other immunomodulatory and immunosuppressive drugs. There was a significant decrease in relapse rate during pregnancy. The prevalence of complications was relatively low, with 4.9% of obstetric and 1.4% neonatal unfavorable outcomes. CONCLUSIONS: Our patients had low degrees of disability, short histories of disease, high drug exposure, and relatively high relapse rate in the year previous to pregnancy. Obstetric and neonatal outcomes were successful in over 90% of our patients.
Assuntos
Esclerose Múltipla/epidemiologia , Complicações na Gravidez/epidemiologia , Adolescente , Adulto , Peso ao Nascer/efeitos dos fármacos , Brasil/epidemiologia , Interpretação Estatística de Dados , Bases de Dados Factuais , Feminino , Acetato de Glatiramer , Humanos , Imunossupressores/efeitos adversos , Imunossupressores/uso terapêutico , Recém-Nascido , Doenças do Recém-Nascido/epidemiologia , Interferon Tipo I/efeitos adversos , Interferon Tipo I/uso terapêutico , Esclerose Múltipla/tratamento farmacológico , Peptídeos/efeitos adversos , Peptídeos/uso terapêutico , Gravidez , Resultado da Gravidez , Proteínas Recombinantes , Recidiva , Estudos Retrospectivos , Adulto JovemRESUMO
UNLABELLED: Orofacial granulomatosis is a term generally used to describe lip swelling secondary to an underlying granulomatous inflammatory process. Granulomatous cheilitis is the histopathological description of such inflammation occurring in the lips and surrounding tissues. Melkersson-Rosenthal syndrome (a triad of orofacial swelling, facial paralysis and a fissured tongue) is one manifestation of orofacial granulomatosis, which more commonly presents as granulomatous cheilitis alone. Oral Crohn's disease also belongs to the entity of orofacial granulomatosis. Most reported cases of orofacial granulomatosis have been in adults and some in adolescents. We present six children presenting with orofacial granulomatosis at an early age (range 5-8 y) whose course points towards the development of Crohn's disease. CONCLUSION: Orofacial granulomatosis in the paediatric population may be an initial manifestation of Crohn's disease and so careful surveillance is recommended.
Assuntos
Doença de Crohn/complicações , Síndrome de Melkersson-Rosenthal/etiologia , Criança , Feminino , Humanos , Masculino , Síndrome de Melkersson-Rosenthal/patologiaRESUMO
The pathogenesis of anemia of the Shay chloroleukemia (SCL) was studied in rats following SC, IP and IV inoculation of chloroma cells. Little difference in survival was noted regardless of the route of inoculation. A decrease in hamatocrit occurred in all SCL rats during approximately the final 48 hours of the disease; however, the anemia was more severe in SC- and IP-inoculated terminal rats than in SCL rats inoculated IV. A reduction in the numbers of normal cellular elements was noted in the femoral bone marrow of most terminal rats studied which was found to correlate inversely with the leukemic blast cell content of the marrow. No correlation was observed between the erythroblast content of the marrow and the degree of anemia. The number of erythroblasts varied from greatly reduced to normal in terminal SCL rats despite severe anemia. Moreover, the greatest reduction of both normal marrow cellularity and erythroblast numbers was observed in IV inoculated rats which consistently displayed the highest hematocrits in the terminal stage of the disease. Thus, the terminal anemia appears to be due primarily to excessive red cell loss. The decrease in erythroblasts, when observed, was most striking in the orthochromatophilic and polychromatophilic stages of erythroid maturation.
Assuntos
Anemia Aplástica/fisiopatologia , Leucemia Mieloide/sangue , Animais , Modelos Animais de Doenças , Eritropoese , RatosRESUMO
To evaluate the erythropoietic potential of rats during pathogenesis of Shay chloroleukemia (SCL), SCL animals were exposed to hypoxia initiated within two hours postinduction of SCL. Increases in hematocrit (HCT) occurred in both SCL and nonleukemic controls during the first seven days of exposure. This was followed by declines in HCT in hypoxic SCL rats similar to that observed in nonhypoxic SCL animals. HCT of nonleukemic controls remained elevated throughout hypoxic exposure. Results suggested that in SCL, erythropoietic homeostatic response mechanisms are functional prior to terminal phases of this disease, whereas anemia-producing mechanisms exceed maximum erythropoietic capacity of these animals during later stages of SCL. The HCT of most SCL rats exposed to hypoxia did not fall below 40% before death. This was in contrast to nonhypoxic SCL animals, which became severely anemic in terminal stages. No survival value was observed despite maintenance of red cell mass at or above normal. The pathogenesis of this leukemia was independent of the leukemic animal's erythropoietic potential.
Assuntos
Eritropoese , Leucemia Mieloide/fisiopatologia , Animais , Hematócrito , Hipóxia/fisiopatologia , Neoplasias Experimentais/fisiopatologia , RatosRESUMO
A thrombocytopoiesis-stimulating factor (TSF) has been purified from human embryonic kidney (HEK) cell culture medium. In the initial purification step, crude HEK cell culture medium was fractionated with saturated ammonium sulfate (step I). The proteins precipitated by 40% to 60% and 60% to 80% ammonium sulfate saturation increased the percent of sulfur 35 incorporation into platelets of assay mice (P less than 0.01). The ammonium sulfate-precipitated proteins that contained significant TSF activity were further refined on Sephadex G-75 columns (step II). The fraction containing the highest specific activity (greatest 35S incorporation into platelets of assay mice per milligram of protein) was further purified by diethylaminoethyl (DEAE)-cellulose column chromatography (step III). TSF activity was eluted from the columns between 0.3 and 1.0 mol/L NaCl. Additional Sephadex chromatography of post-DEAE-chromatographic preparations further increased the purity of the TSF (step IV). TSF from this four-step procedure was further processed on a DEAE-high-performance liquid chromatography (HPLC) column (step Va) or size exclusion (SE)-HPLC columns (step Vb). After HPLC, the activity was localized in a region corresponding to a retention time of 6 to 8 minutes for the DEAE-HPLC, but longer times were found after SE-HPLC. TSF was further purified by additional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and SE-HPLC (step VI). The final product had significant TSF activity and represented a purification of approximately 500,000-fold. It was also shown that the isoelectric pH of partially purified TSF was 4.7 and the molecular weight of the more highly purified preparation was approximately 32,000. After extraction by a combination of chromatographic procedures, a single homogeneous product was obtained.
Assuntos
Glicoproteínas/isolamento & purificação , Rim/análise , Trombopoetina/isolamento & purificação , Sulfato de Amônio , Animais , Plaquetas/metabolismo , Células Cultivadas , Fracionamento Químico , Cromatografia DEAE-Celulose , Cromatografia em Gel , Cromatografia Líquida de Alta Pressão/métodos , Meios de Cultura/análise , Eletroforese em Gel de Poliacrilamida , Embrião de Mamíferos , Humanos , Focalização Isoelétrica , Masculino , Camundongos , Camundongos Endogâmicos C3H , Proteínas/isolamento & purificação , Radioisótopos de Enxofre , Trombocitose/sangueRESUMO
To determine the extent intrinsic erythrocyte defects and/or extrinsic factors were involved in anemia of rats bearing Shay chloroleukemia (SCL), survival of 3H-DFP labeled erythrocytes was studied in leukemic and nonleukemic hosts. Red blood cells labeled before induction of leukemia, were rapidly lost from the peripheral circulation of SCL rats in terminal stages of disease. However, labeled erythrocytes from terminal SCL animals displayed normal lifespans when transfused into nonleukemic controls. Thus the anemia of this leukemia probably resulted from extrinsic factors associated with the leukemic process. Hemorrhage appeared to be primarily responsible for the anemia of this disease.