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1.
Osteoporos Int ; 33(3): 599-610, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34617151

RESUMO

Higher incidences of fractures are seen in people with type 1 diabetes (T1D), but knowledge on different fracture sites is sparse. We found a higher incidence mainly for distal fracture sites in people with T1D compared to controls. It must be further studied which fractures attributed to the higher incidence rates (IRs) at specific sites. INTRODUCTION: People with T1D have a higher incidence of fractures compared to the general population. However, sparse knowledge exists on the incidence rates of individual fracture sites. Therefore, we examined the incidence of various fracture sites in people with newly treated T1D compared to matched controls. METHODS: All people from the UK Clinical Practice Research Datalink GOLD (1987-2017), of all ages with a T1D diagnosis code (n = 6381), were included. People with T1D were matched by year of birth, sex, and practice to controls (n = 6381). Fracture IRs and incidence rate ratios (IRRs) were calculated. Analyses were stratified by fracture site and sex. RESULTS: The IR of all fractures was significantly higher in people with T1D compared to controls (IRR: 1.39 (CI95%: 1.24-1.55)). Compared to controls, the IRR for people with T1D was higher for several fracture sites including carpal (IRR: 1.41 (CI95%: 1.14-1.75)), clavicle (IRR: 2.10 (CI95%: 1.18-3.74)), foot (IRR: 1.70 (CI95%: 1.23-2.36)), humerus (IRR: 1.46 (CI95%: 1.04-2.05)), and tibia/fibula (IRR: 1.67 CI95%: 1.08-2.59)). In women with T1D, higher IRs were seen at the ankle (IRR: 2.25 (CI95%: 1.10-4.56)) and foot (IRR: 2.11 (CI95%: 1.27-3.50)), whereas in men with T1D, higher IRs were seen for carpal (IRR: 1.45 (CI95%: 1.14-1.86)), clavicle (IRR: 2.13 (CI95%: 1.13-4.02)), and humerus (IRR: 1.77 (CI95%: 1.10-2.83)) fractures. CONCLUSION: The incidence of carpal, clavicle, foot, humerus, and tibia/fibula fractures was higher in newly treated T1D, but there was no difference at other fracture sites compared to controls. Therefore, the higher incidence of fractures in newly treated people with T1D has been found mainly for distal fracture sites.


Assuntos
Diabetes Mellitus Tipo 1 , Fraturas Ósseas , Diabetes Mellitus Tipo 1/complicações , Diabetes Mellitus Tipo 1/epidemiologia , Feminino , Fraturas Ósseas/epidemiologia , Fraturas Ósseas/etiologia , Humanos , Úmero , Incidência , Masculino , Articulação do Punho
2.
Diabet Med ; 37(12): 2098-2108, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-31990417

RESUMO

AIM: To investigate the trends in non-traumatic lower limb amputation in people with and without diabetes. METHODS: From the Danish National Patient Register, all people with either type 1 or type 2 diabetes (n = 462 743) as well as a group of people without diabetes from the general population (n = 1 388 886) were identified and separated into three groups based on diabetes type. Among these, 17 265 amputations were identified between 1997 and 2017 and stratified into trans-femoral amputations, trans-tibial amputations and amputations below the ankle using surgical codes. Annual changes were described using least-squares linear regression. RESULTS: The yearly mean decrease in incidence rate of amputation per 1000 person-years was -0.032 [95% CI: -0.062, -0.001], -0.022 [-0.032, -0.012] and -0.006 [-0.009, -0.003] for trans-femoral amputation, -0.072 [-0.093, -0.052], -0.090 [-0.102, -0.078] and -0.015 [-0.016, -0.013] for trans-tibial amputation, and -0.055 [-0.080, -0.020], -0.075 [-0.090, -0.060] and -0.011 [-0.014, -0.007] for amputation below the ankle in people with type 1 diabetes, people with type 2 diabetes and people without diabetes, respectively. CONCLUSIONS: Over recent decades, the incidence of amputation has decreased significantly in people with diabetes and in the general population without diabetes.


Assuntos
Amputação Cirúrgica/tendências , Diabetes Mellitus Tipo 1/complicações , Diabetes Mellitus Tipo 2/complicações , Extremidade Inferior/cirurgia , Doença Arterial Periférica/cirurgia , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Dinamarca , Pé Diabético/etiologia , Pé Diabético/cirurgia , Procedimentos Endovasculares , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Doença Arterial Periférica/etiologia , Estudos Retrospectivos , Procedimentos Cirúrgicos Vasculares
3.
Clin Nutr ESPEN ; 35: 141-145, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31987108

RESUMO

BACKGROUND: Liver fibrosis is a well-known complication of long-term use of parenteral nutrition in patients with intestinal failure associated to the nutrient composition in parenteral nutrition. This study investigates the prevalence of significant liver fibrosis and identifies risk factors for liver fibrosis. METHODS: This was a retrospective study of 35 parenteral nutrition-dependent patients with intestinal failure and 54 patients with intestinal insufficiency and oral nutrition only with a valid liver stiffness measurement obtained with transient elastography from November 2016 to August 2018. Clinical and demographic parameters including age, fat mass index and fat-free mass index, intact colon or colectomy, and nutritional management were analyzed for their association with liver stiffness. RESULTS: A prevalence for liver fibrosis (liver stiffness >7.0 kPa) was established at 37.1% in parenteral nutrition-dependent patients and at 22.2% in patients on oral nutrition. Several factors were significantly and independently associated with liver fibrosis including lipids in home parenteral nutrition (OR 10.66, p = 0.010) and colectomies (OR 3.24, p = 0.036). CONCLUSION: More than a third of patients receiving home parenteral nutrition have liver fibrosis. Several risk factors were demonstrated such as the amount of lipids and performed colectomies despite current international guidelines for lipids are followed. Our findings emphasize suggest a new perspective to prevent significant hepatic complications: colectomies.


Assuntos
Cirrose Hepática , Desnutrição , Nutrição Parenteral no Domicílio/efeitos adversos , Adulto , Idoso , Colo , Feminino , Humanos , Enteropatias , Intestinos , Fígado , Cirrose Hepática/epidemiologia , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Razão de Chances , Nutrição Parenteral Total , Prevalência , Estudos Retrospectivos , Fatores de Risco
4.
Osteoporos Int ; 31(3): 447-455, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31838553

RESUMO

Patients with diabetes have an increased risk of fractures. In this study, subtrochanteric and femoral shaft fractures were increased in patients with type 1 diabetes compared with the general population. In the light of this, more evidence points towards an association between diabetes and atypical femoral fractures. INTRODUCTION: Patients with diabetes have an increased risk of femoral fractures, but little is known about the risk of atypical femoral fractures (AFFs). The aim of this study was to identify the risk of subtrochanteric and femoral shaft (ST/FS) fractures and estimate the risk of AFFs in patients with type 1 (T1D) and type 2 diabetes (T2D). METHODS: From the nationwide Danish National Patient Register, we identified patients with T1D (n = 19,896), T2D (n = 312,188), and sex- and aged-matched controls without diabetes (n = 996,252) from the general population and all ST/FS fractures (n = 7509). Data were analyzed using a Cox proportional-hazards model and the incidence rate and rate ratio of ST/FS fractures were estimated. RESULTS: The incidence rate of ST/FS fractures in T1D was 52.14 events per 100,000 person years and 73.21 per 100,000 person years in T2D. T1D was associated with an increased risk of ST/FS (HR 2.07 (95% CI 1.68-2.56)), whereas T2D was not (HR 0.99 (95% CI 0.94-1.10)). Previous ST/FS fractures were associated with an increased risk of subsequent ST/FS fractures (HR 6.95 (95% CI 6.00-8.05)) and the use of bisphosphonates with an increased risk of ST/FS fractures (HR 1.72 (95% CI 1.54-1.91)). CONCLUSION: Patients with T1D have a higher risk of ST/FS fractures compared with sex- and age-matched controls. Since a proportion of ST/FS fractures are classified as AFFs, this could point towards the fact that AFFs also are increased in patients with T1D, but not T2D.


Assuntos
Diabetes Mellitus Tipo 2 , Fraturas do Fêmur , Fraturas do Quadril , Osteoporose , Idoso , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/epidemiologia , Difosfonatos , Feminino , Fraturas do Fêmur/epidemiologia , Fraturas do Fêmur/etiologia , Fraturas do Quadril/epidemiologia , Fraturas do Quadril/etiologia , Humanos , Incidência , Masculino
5.
Osteoporos Int ; 30(8): 1663-1670, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31129687

RESUMO

People with diabetes have an increased risk of fractures, and in this study, the effect of hypoglycaemia and insulin on this risk was investigated. Type 1 diabetes and hypoglycaemia did increase the fracture risk, and prevention of hypoglycaemia is thus an important focus area in the prevention of fractures. INTRODUCTION: Studies have shown that type 1 diabetes (T1D) and type 2 diabetes (T2D) are associated with increased risk of fractures. Especially, subjects with T1D have an increased risk of fractures. The purpose of this study was to investigate the association of T1D, hypoglycaemia and insulin on fracture risk. METHODS: A cohort study with T1D subjects (n = 19,896) and T2D subjects (n = 312,188) matched with subjects from the general populated (n = 996,252) and a nested case-control study with T1D subjects with fracture (n = 895) as cases and T1D subjects without (n = 2685) as controls were conducted based on subjects from the Danish National Patient Registry (DNPR). RESULTS: T1D (HR = 2.47, 95% CI 2.37 to 2.59), age (HR = 1.05, 95% CI 1.05 to 1.05), previous fracture (HR = 1.95, 95% CI 1.92 to 1.99) and being female (HR = 2.06, 95% CI 2.04 to 2.09) increased the risk of fractures. Also, T2D (HR = 1.14, 95% CI 1.11 to 1.18) increased the risk of proximal upper arm and shoulder fractures. T1D (HR = 2.41, 95% CI 2.20 to 2.65) increased the risk of hip and femoral region fractures. Hypoglycaemia (OR = 1.58, 95% CI 1.27 to 1.97) increased the risk of fractures, whereas insulin use did not change the risk. CONCLUSIONS: Hypoglycaemic episodes are associated with increased fracture risk, and the frequency of hypoglycaemic episodes leading to hospital admission was above 16% for T1D subjects. Prevention of hypoglycaemia is thus an important focus area in the prevention of fractures.


Assuntos
Diabetes Mellitus Tipo 1/complicações , Hipoglicemia/complicações , Fraturas por Osteoporose/etiologia , Adolescente , Adulto , Idoso , Estudos de Casos e Controles , Criança , Estudos de Coortes , Dinamarca/epidemiologia , Diabetes Mellitus Tipo 1/tratamento farmacológico , Diabetes Mellitus Tipo 1/epidemiologia , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/epidemiologia , Feminino , Humanos , Hipoglicemia/tratamento farmacológico , Hipoglicemia/epidemiologia , Insulina/uso terapêutico , Masculino , Pessoa de Meia-Idade , Fraturas por Osteoporose/epidemiologia , Modelos de Riscos Proporcionais , Sistema de Registros , Medição de Risco/métodos , Adulto Jovem
6.
Phys Chem Chem Phys ; 20(3): 1716-1723, 2018 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-29265133

RESUMO

Glycerol-water mixtures were studied at molar concentrations ranging from xgly = 1 (neat glycerol) to xgly = 0.3 using shear mechanical spectroscopy. We observed a low frequency mode in neat glycerol, similar to what has been reported for monohydroxy alcohols. This mode has no dielectric counterpart and disappears with increased water concentration. We propose that the hydrogen-bonded network formed between glycerol molecules is responsible for the observed slow mode and that water acts as a plasticizer for the overall dynamics and as a lubricant softening the hydrogen-bonding contribution to the macroscopic viscosity of this binary system.

7.
Transl Psychiatry ; 7(4): e1087, 2017 04 11.
Artigo em Inglês | MEDLINE | ID: mdl-28398342

RESUMO

Deficits in information processing and cognition are among the most robust findings in schizophrenia patients. Previous efforts to translate group-level deficits into clinically relevant and individualized information have, however, been non-successful, which is possibly explained by biologically different disease subgroups. We applied machine learning algorithms on measures of electrophysiology and cognition to identify potential subgroups of schizophrenia. Next, we explored subgroup differences regarding treatment response. Sixty-six antipsychotic-naive first-episode schizophrenia patients and sixty-five healthy controls underwent extensive electrophysiological and neurocognitive test batteries. Patients were assessed on the Positive and Negative Syndrome Scale (PANSS) before and after 6 weeks of monotherapy with the relatively selective D2 receptor antagonist, amisulpride (280.3±159 mg per day). A reduced principal component space based on 19 electrophysiological variables and 26 cognitive variables was used as input for a Gaussian mixture model to identify subgroups of patients. With support vector machines, we explored the relation between PANSS subscores and the identified subgroups. We identified two statistically distinct subgroups of patients. We found no significant baseline psychopathological differences between these subgroups, but the effect of treatment in the groups was predicted with an accuracy of 74.3% (P=0.003). In conclusion, electrophysiology and cognition data may be used to classify subgroups of schizophrenia patients. The two distinct subgroups, which we identified, were psychopathologically inseparable before treatment, yet their response to dopaminergic blockade was predicted with significant accuracy. This proof of principle encourages further endeavors to apply data-driven, multivariate and multimodal models to facilitate progress from symptom-based psychiatry toward individualized treatment regimens.


Assuntos
Transtornos Cognitivos/fisiopatologia , Transtornos Cognitivos/psicologia , Processos Mentais/fisiologia , Esquizofrenia/classificação , Esquizofrenia/fisiopatologia , Psicologia do Esquizofrênico , Adulto , Algoritmos , Amissulprida , Antipsicóticos/efeitos adversos , Antipsicóticos/uso terapêutico , Transtornos Cognitivos/diagnóstico , Transtornos Cognitivos/tratamento farmacológico , Eletroencefalografia/efeitos dos fármacos , Potenciais Evocados/efeitos dos fármacos , Potenciais Evocados/fisiologia , Feminino , Seguimentos , Humanos , Aprendizado de Máquina , Masculino , Processos Mentais/efeitos dos fármacos , Testes Neuropsicológicos/estatística & dados numéricos , Distribuição Normal , Escalas de Graduação Psiquiátrica/estatística & dados numéricos , Psicometria , Valores de Referência , Esquizofrenia/diagnóstico , Esquizofrenia/tratamento farmacológico , Sulpirida/análogos & derivados , Sulpirida/uso terapêutico
8.
J Chem Phys ; 143(13): 134501, 2015 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-26450317

RESUMO

Isothermal crystallization of the mono-hydroxyl alcohol n-butanol was studied with dielectric spectroscopy in real time. The crystallization was carried out using two different sample cells at 15 temperatures between 120 K and 134 K. Crystallization is characterized by a decrease of the dielectric intensity. In addition, a shift in relaxation times to shorter times was observed during the crystallization process for all studied temperatures. The two different sample environments induced quite different crystallization behaviors, consistent and reproducible over all studied temperatures. An explanation for the difference was proposed on the background of an Avrami analysis and a Maxwell-Wagner analysis. Both types of analysis suggest that the morphology of the crystal growth changes from a higher dimension to a lower at a point during the crystallization. More generally, we conclude that a microscopic interpretation of crystallization measurements requires multiple probes, sample cells, and protocols.

9.
Philos Trans A Math Phys Eng Sci ; 371(1999): 20120469, 2013 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-23960227

RESUMO

The expression of genes in the cell is controlled by a complex interaction network involving proteins, RNA and DNA. The molecular events associated with the nodes of such a network take place on a variety of time scales, and thus cannot be regarded as instantaneous. In many cases, the cell is robust with respect to the delay in gene expression control, behaving as if it were instantaneous. However, there are specific cases in which delay gives rise to temporal oscillations. This is the case, for example, of the expression of tumour-suppressor protein p53, of protein Hes1, involved in the differentiation of stem cells, of NFkB and Wnt, in which case delay arises implicitly from the structure of the associated network. By means of delay rate equations, we study the kinetics of small regulatory networks, emphasizing the role of delay in an evolutionary context. These models suggest that oscillations are a typical outcome of the dynamics of regulatory networks, and evolution has to work to avoid them when not required (and not vice versa).


Assuntos
Relógios Biológicos/fisiologia , Evolução Molecular , Regulação da Expressão Gênica/genética , Modelos Genéticos , Proteoma/metabolismo , Animais , Simulação por Computador , Humanos
10.
Theor Popul Biol ; 84: 72-86, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23298763

RESUMO

We study an individual based model describing competition in space between two different alleles. Although the model is similar in spirit to classic models of spatial population genetics such as the stepping stone model, here however space is continuous and the total density of competing individuals fluctuates due to demographic stochasticity. By means of analytics and numerical simulations, we study the behavior of fixation probabilities, fixation times, and heterozygosity, in a neutral setting and in cases where the two species can compete or cooperate. By concluding with examples in which individuals are transported by fluid flows, we argue that this model is a natural choice to describe competition in marine environments.


Assuntos
Demografia , Genética Populacional , Heterozigoto , Biologia Marinha , Modelos Teóricos , Processos Estocásticos
11.
Phys Rev Lett ; 106(5): 058701, 2011 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-21405444

RESUMO

Scientific paradigms have a tendency to rise fast and decline slowly. This asymmetry reflects the difficulty in developing a truly original idea, compared to the ease at which a concept can be eroded by numerous modifications. Here we formulate a model for the emergence and spread of ideas which deals with this asymmetry by constraining the ability of agents to return to already abandoned concepts. The model exhibits a fairly regular pattern of global paradigm shifts, where older paradigms are eroded and subsequently replaced by new ones. The model sets the theme for a new class of pattern formation models, where local dynamics breaks the detailed balance in a way that prevents old states from defending themselves against new nucleating or invading states. The model allows for frozen events in terms of the coexistence of multiple metastable states.

12.
Phys Biol ; 6(3): 036009, 2009 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-19461130

RESUMO

Oscillations play an important physiological role in a variety of biological systems. For example, respiration and carbohydrate synthesis are coupled to the circadian clock in cyanobacteria (Ishiura et al 1998 Science 281 1519) and ultradian oscillations with time periods of a few hours have been observed in immune response (NF-kappaB, Hoffmann et al 2002 Science 298 1241, Neson et al 2004 Science 306 704), apoptosis (p53, Lahav et al 2004 Nat. Genet. 36 53), development (Hes, Hirata et al 2002 Science 298 840) and growth hormone secretion (Plotsky and Vale 1985 Science 230 461, Zeitler et al 1991 Proc. Natl. Acad. Sci. USA 88 8920). Here we discuss how any bistable system can be 'frustrated' to produce oscillations of a desired nature--we use the term frustration, in analogy to frustrated spins in antiferromagnets, to refer to the addition of a negative feedback loop that destabilizes the bistable system. We show that the molecular implementation can use a wide variety of methods ranging from translation regulation, using small non-coding RNAs, to targeted protein modification to transcriptional regulation. We also introduce a simple graphical method for determining whether a particular implementation will produce oscillations. The shape of the resulting oscillations can be readily tuned to produce spiky and asymmetric oscillations--quite different from the shapes produced by synthetic oscillators (Elowitz and Leibler 2000 Nature 403 335, Fung et al 2005 Nature 435 118). The time period and amplitude can also be manipulated and these oscillators are easy to reset or switch on and off using a tunable external input. The mechanism of frustrated bistability could thus prove to be an easily implementable way to synthesize flexible, designable oscillators.


Assuntos
Relógios Biológicos , Modelos Biológicos , Ritmo Circadiano/fisiologia , Proteínas/química , RNA não Traduzido/química
13.
Phys Biol ; 4(2): R1-17, 2007 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-17664651

RESUMO

The development of new techniques to quantitatively measure gene expression in cells has shed light on a number of systems that display oscillations in protein concentration. Here we review the different mechanisms which can produce oscillations in gene expression or protein concentration using a framework of simple mathematical models. We focus on three eukaryotic genetic regulatory networks which show 'ultradian' oscillations, with a time period of the order of hours, and involve, respectively, proteins important for development (Hes1), apoptosis (p53) and immune response (NF-kappaB). We argue that underlying all three is a common design consisting of a negative feedback loop with time delay which is responsible for the oscillatory behaviour.


Assuntos
Biofísica/métodos , Biologia Celular , Regulação da Expressão Gênica , Transdução de Sinais , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Humanos , Modelos Biológicos , Modelos Teóricos , NF-kappa B/metabolismo , Oscilometria , Proteínas/metabolismo , Biologia de Sistemas , Fatores de Tempo , Proteína Supressora de Tumor p53/metabolismo
15.
Phys Rev Lett ; 87(16): 164101, 2001 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-11690205

RESUMO

We study the nature of the phase transition in the multifractal formalism of the harmonic measure of diffusion limited aggregates. Contrary to previous work that relied on random walk simulations or ad hoc models to estimate the low probability events of deep fjord penetration, we employ the method of iterated conformal maps to obtain an accurate computation of the probability of the rarest events. We resolve probabilities as small as 10(-35). We show that the generalized dimensions D(q) are infinite for q

16.
Environ Sci Technol ; 35(14): 3055-63, 2001 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-11478262

RESUMO

The halocarbon CFC-11 has extensively been used as a blowing agent for polyurethane (PUR) insulation foams in home appliances and for residential and industrial construction. Release of CFCs is an important factor in the depletion of the ozone layer. For CFC-11 the future atmospheric concentrations will mainly depend on the continued release from PUR foams. Little is known about rates and time frames of the CFC release from foams especially after treatment and disposal of foam containing waste products. The CFC release is mainly controlled by slow diffusion out through the PUR. From the literature and by reevaluation of an old reported experiment, diffusion coefficients in the range of 0.05-1.7 x 10(-14) m2 s-1 were found reflecting differences in foam properties and experimental designs. Laboratory experiments studying the distribution of CFC in the foam and the short-term releases after shredding showed that about 40% of the CFC is solubilized in the PUR phase, and that up to 10% of the total content will be released within a few weeks if the foam is shredded down to 2-cm sized pieces. For smaller pieces the quick release will be larger. Fifty percent of residual CFC content will be released within 9-300 years from 2-cm pieces based on the range in diffusion coefficients reported. For larger pieces the initial release is insignificant, and the release time frames are much longer than for the shredded foam.


Assuntos
Poluentes Atmosféricos/análise , Clorofluorcarbonetos/química , Poliuretanos/química , Clorofluorcarbonetos/análise , Difusão , Cinética , Tamanho da Partícula , Eliminação de Resíduos , Volatilização
17.
Phys Rev Lett ; 86(6): 1031-3, 2001 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-11178002

RESUMO

We studied the thermodynamics of a homopolymeric chain with both van der Waals and directed hydrogen bond interaction. The effect of hydrogen bonds is to reduce dramatically the entropy of low-lying states and to give rise to long-range order and to conformations displaying secondary structures. For compact polymers a transition is found between helix-rich states and low-entropy sheet-dominated states. The consequences of this transition for protein folding and, in particular, for the problem of prions are discussed.


Assuntos
Ligação de Hidrogênio , Conformação Molecular , Polímeros/química , Modelos Moleculares , Proteínas/química
18.
Biophys J ; 79(5): 2722-7, 2000 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11053144

RESUMO

Thermodynamic measurements of proteins indicate that the folding to the native state takes place either through stable intermediates or through a two-state process without intermediates. The rather short folding times of proteins indicate that folding is guided through some sequence of contact bindings. We discuss the possibility of reconciling a two-state folding event with a sequential folding process in a schematic model of protein folding. We propose a new dynamical transition temperature that is lower than the temperature at which proteins in equilibrium unfold. This is in qualitative agreement with observations of in vivo protein folding activity quantified by chaperone concentration in Escherichia coli. Finally, we discuss our framework in connection with the unfolding of proteins at low temperatures.


Assuntos
Dobramento de Proteína , Fenômenos Biofísicos , Biofísica , Modelos Químicos , Método de Monte Carlo , Termodinâmica
19.
Folia Phoniatr Logop ; 52(1-3): 126-35, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10474012

RESUMO

Like logopedics, augmentative and alternative communication (AAC) has a short history and a long past. In the 1950s and 60s the field of AAC emerged as a response to the need of individuals who, despite years of 'traditional speech therapy', had not developed adequate oral communication skills, and for whom compensatory rather than remedial approaches were thus deemed advisable. Various trends like the shift from form to function in language development research, dissemination of sign language, use of non-speech graphic symbols, advances in computer technology, and international collaboration have all contributed to AAC's present-day status as a multidisciplinary enterprise involving speech-language therapists and an array of other professions. Clinical experience, for lack of comprehensive empirical studies, seems to indicate that AAC is warranted for congenital as well as acquired communication disorders.


Assuntos
Distúrbios da Fala/terapia , Fonoterapia/métodos , Patologia da Fala e Linguagem , Humanos
20.
Vaccine ; 17(9-10): 1057-64, 1999 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-10195615

RESUMO

Bovine Viral Diarrhea Virus (BVDV) is a major pathogen of cattle in most countries. The main reservoir of virus in herds are BVDV persistently infected animals, which arise as a result of infection of the bovine fetus early in gestation. The spread of virus to the unborn fetus may be prevented by vaccination of the dam. We describe in this report the production and initial testing of an inactivated subunit vaccine against BVDV. The vaccine is based on production of antigen in primary bovine cell cultures, extraction of antigens from infected cells with detergent, chromatographic purification, concentration, and insertion of antigens into immune stimulating complexes (ISCOMs). Vaccines based on two different Danish strains of BVDV were injected into calves and the antisera produced were tested for neutralising activity against a panel of Danish BVDV strains. The two vaccines induced different neutralisation responses, which seem to partly complement each other. The implication of these observations for successful vaccination against BVDV is discussed.


Assuntos
Adjuvantes Imunológicos/síntese química , Doença das Mucosas por Vírus da Diarreia Viral Bovina/prevenção & controle , Vírus da Diarreia Viral Bovina/imunologia , ISCOMs/imunologia , Animais , Anticorpos Antivirais/biossíntese , Bovinos , Células Cultivadas , Reações Cruzadas , Eletroforese em Gel de Poliacrilamida
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