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1.
Environ Chall (Amst) ; 11: None, 2023 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37214236

RESUMO

Sanitation systems involving onsite storage of faecal matter cause excreta to undergo transformation and primary treatment in-situ. However, little is known about the transformation pathway followed by fresh faeces while contained in situ. The current paper investigated this transformation under ambient conditions during a 16-week in-situ-storage period. Moisture content, drying kinetics, rheological, physicochemical, and thermal properties were analysed to determine the effects of ageing. The faeces experienced dehydration, mainly affecting moisture-dependent characteristics. Moisture content decreased from 79%wt to 26%wt, and water activity of 0.67, which corresponds mainly to the removal of interstitial bound water, reducing mass by 72%. The decreasing moisture content expectantly reduced drying ability, flowability and thermal properties (heat capacity and thermal conductivity). During this period, negligible biodegradation was recorded (volatile solids reduced by 3%), resulting in consistent chemical oxygen demand, particle size, carbon content and calorific values. Ammonium and nitrates decreased, but total nitrogen remained unchanged. Therefore, ageing affects nitrogen chemical forms and not nutrient composition. The findings demonstrate the benefits of source separation and in particular ventilated storage as a passive way to pre-treat and recover resources from faecal material.

3.
J Memb Sci ; 584: 343-352, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31423048

RESUMO

The integration of membrane distillation with reverse electrodialysis has been investigated as a sustainable sanitation solution to provide clean water and electrical power from urine and waste heat. Reverse electrodialysis was integrated to provide the partial remixing of the concentrate (urine) and diluate (permeate) produced from the membrane distillation of urine. Broadly comparable power densities to those of a model salt solution (sodium chloride) were determined during evaluation of the individual and combined contribution of the various monovalent and multivalent inorganic and organic salt constituents in urine. Power densities were improved through raising feed-side temperature and increasing concentration in the concentrate, without observation of limiting behaviour imposed by non-ideal salt and water transport. A further unique contribution of this application is the limited volume of salt concentrate available, which demanded brine recycling to maximise energy recovery analogous to a battery, operating in a 'state of charge'. During recycle, around 47% of the Gibbs free energy was recoverable with up to 80% of the energy extractable before the concentration difference between the two solutions was halfway towards equilibrium which implies that energy recovery can be optimised with limited effect on permeate quality. This study has provided the first successful demonstration of an integrated MD-RED system for energy recovery from a limited resource, and evidences that the recovered power is sufficient to operate a range of low current fluid pumping technologies that could help deliver off-grid sanitation and clean water recovery at single household scale.

4.
Sep Sci Technol ; 53(9): 1372-1382, 2018 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-33551521

RESUMO

In this study, membrane distillation is evaluated as a technology for non-sewered sanitation, using waste heat to enable separation of clean water from urine. Whilst membrane fouling was observed for urine, wetting was not evident and product water quality met the proposed discharge standard, despite concentration of the feed. Fouling was reversible using physical cleaning, which is similar to previous membrane studies operating without pressure as the driving force. High COD reduction was achieved following faecal contamination, but mass transfer was impeded and wetting occurred which compromised permeate quality, suggesting upstream intervention is demanded to limit the extent of faecal contamination. (100 words).

5.
J Memb Sci ; 523: 235-246, 2017 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-28163357

RESUMO

Transformation of the tube-side mass transfer coefficient derived in hollow fibre membrane contactors (HFMC) of different characteristic length scales (equivalent diameter and fibre length) has been studied when operated in the low Graetz range (Gz<10). Within the low Gz range, mass transfer is generally described by the Graetz problem (Sh=3.67) which assumes that the concentration profile comprises a constant shape over the fibre radius. In this study, it is experimentally evidenced that this assumption over predicts mass transfer within the low Graetz range. Furthermore, within the low Gz range (below 2), a proportional relationship between the experimentally determined mass transfer coefficient (Kov ) and the Graetz number has been identified. For Gz numbers below 2, the experimental Sh number approached unity, which suggests that mass transfer is strongly dependent upon diffusion. However, within this diffusion controlled region of mass transfer, tube-side fluid velocity remained important. For Gz numbers above 2, Sh could be satisfactorily described by extension to the Lévêque solution, which can be ascribed to the constrained growth of the concentration boundary layer adjacent to the fibre wall. Importantly this study demonstrates that whilst mass transfer in the low Graetz range does not explicitly conform to either the Graetz problem or classical Lévêque solution, it is possible to transform the experimentally derived overall mass transfer coefficient (Kov ) between characteristic length scales (dh and L). T h is was corroborated by comparison of the empirical relationship determined in this study (Sh=0.36Gz) with previously published studies operated in the low Gz range. This analysis provides important insight for process design when slow tube-side flows, or low Schmidt numbers (coincident with gases) constrain operation of hollow fibre membrane contactors to the low Gz range.

6.
Physiotherapy ; 103(1): 40-47, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27641499

RESUMO

BACKGROUND: In 1940s, it was proposed that frozen shoulder progresses through a self-limiting natural history of painful, stiff and recovery phases, leading to full recovery without treatment. However, clinical evidence of persistent limitations lasting for years contradicts this assumption. OBJECTIVES: To assess evidence for the natural history theory of frozen shoulder by examining: (1) progression through recovery phases, and (2) full resolution without treatment. DATA SOURCES: MEDLINE, PubMed, EBSCO CINAHL and PEDro database searches augmented by hand searching. STUDY SELECTION: Cohort or randomised controlled trials with no-treatment comparison groups including adults with frozen shoulder who received no treatment and reporting range of motion, pain or function for ≥6 months. DATA EXTRACTION: Reviewers assessed study eligibility and quality, and extracted data before reaching consensus. Limited early range-of-motion improvements and greater late improvements defined progression through recovery phases. Restoration of normal range of motion and previous function defined full resolution. RESULTS: Of 508 citations, 13 articles were reviewed and seven were included in this review. Low-quality evidence suggested that no treatment yielded some, but not complete, improvement in range of motion after 1 to 4 years of follow-up. No evidence supported the theory of progression through recovery phases to full resolution without treatment. On the contrary, moderate-quality evidence from three randomised controlled trials with longitudinal data demonstrated that most improvement occurred early, not late. LIMITATIONS: Low-quality evidence revealed the weakness of longstanding assumptions about frozen shoulder. CONCLUSION: Contradictory evidence and a lack of supporting evidence shows that the theory of recovery phases leading to complete resolution without treatment for frozen shoulder is unfounded.


Assuntos
Bursite/fisiopatologia , Bursite/reabilitação , Modalidades de Fisioterapia , Humanos , Amplitude de Movimento Articular , Recuperação de Função Fisiológica , Dor de Ombro/fisiopatologia , Dor de Ombro/reabilitação , Fatores de Tempo
7.
Physiol Biochem Zool ; 89(3): 225-32, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27153132

RESUMO

Mummichogs prefer seawater (SW) but have wide ability to acclimate to extreme temperatures and salinities. In the field, minnow trapping revealed that mummichogs move progressively into low-salinity warmer water during early spring after ice melt and show significant aversion to colder temperatures and high salinity. First appearance in estuarine shallows occurred above 10°C, and catch increased to 21°C over 4 wk. Three-spine sticklebacks (Gasterosteus aculeatus) also preferred warmer low-salinity locations but preferred slowing streams, whereas mummichogs preferred tidal ponds. In the laboratory, artificial haloclines tested isothermal salinity preference, between 28‰ full-strength SW (below) and 10% SW (3.0‰; above). Mummichogs of both sexes acclimated to 5°C in SW strongly preferred SW. Freshwater (0% SW)-acclimated mummichogs at 21°C also preferred SW, but of sexually mature fish acclimated to 21°C SW, only the males preferred SW; the females showed no significant preference for SW, meaning they freely entered low salinity. SW preference was manifested by a stereotypic passive aversion to the dilute upper layer at the halocline. We conclude that the overall movement of mummichogs into summer breeding grounds of low salinity is driven by maturation of females and their preference for warmer water regardless of salinity.


Assuntos
Comportamento Animal , Peixes/fisiologia , Salinidade , Tolerância ao Sal , Aclimatação , Animais , Ecossistema , Feminino , Masculino , Estações do Ano , Movimentos da Água
8.
Calcif Tissue Int ; 93(3): 241-8, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23756612

RESUMO

Bisphosphonate (BP)-related osteonecrosis of the jaw (BRONJ) presents with necrotic bone in the mouth in the setting of BP exposure. It has been studied in cancer patients taking high-dose BP, but BRONJ has also been noted in patients taking lower-dose BP for osteoporosis. The purpose of this study was to characterize the phenotypes and outcomes in a large series of patients with osteoporosis and BRONJ in the setting of BP exposure. We conducted a retrospective case series. The sample was composed of subjects with BRONJ and osteoporosis. Subjects with a history of BP treatment for myeloma or metastatic cancer to the bones were excluded. Descriptive statistics were computed for the study variables. Ninety-one cases of BRONJ met the inclusion criteria. Subjects had a median age of 71 years and were predominantly female (94.5 %). The median time of BP exposure was 60 months (range 2-120). Most subjects were treated with alendronate (82.4 %). The mandible was involved more frequently (58.2 %) than the maxilla (37.3 %). Subjects commonly (65.9 %), but not universally, reported pain. For subjects with treatment outcome data (n = 0), most reported improvement (80.0 %). Although BRONJ is an uncommon condition, the absolute number of cases is fairly large due to the very large number of patients taking BPs for osteoporosis. The findings of this study confirm that BRONJ primarily affects the mandible, a substantial minority present without pain, and patients typically improve with treatment.


Assuntos
Osteonecrose da Arcada Osseodentária Associada a Difosfonatos/diagnóstico , Difosfonatos/efeitos adversos , Osteoporose/complicações , Osteoporose/tratamento farmacológico , Idoso , Idoso de 80 Anos ou mais , Osteonecrose da Arcada Osseodentária Associada a Difosfonatos/epidemiologia , Estudos de Coortes , Feminino , Humanos , Masculino , Mandíbula/efeitos dos fármacos , Pessoa de Meia-Idade , Necrose , Fenótipo , Estudos Retrospectivos , Fatores de Risco , Resultado do Tratamento
9.
Osteoporos Int ; 24(1): 237-44, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22707065

RESUMO

UNLABELLED: Bisphosphonate-related osteonecrosis of the jaw (BONJ) is an adverse effect of bisphosphonate use with a poorly described epidemiology in osteoporosis patients. We examined the literature and two new cohorts for BONJ. The literature suggests an incidence rate of 0.028 % to 4.3 %. Our cohort studies found an incidence of 0.02 % (95 % CI 0.004 %-0.11 %). INTRODUCTION: We examined the epidemiology of BONJ associated with osteoporosis dosing of bisphosphonates. METHODS: First, we systematically searched the literature about osteoporosis BONJ. Identified studies were abstracted by two authors. Second, we attempted to estimate the relative risk of BONJ among bisphosphonate users with osteoporosis. Two different large insurance databases, one from 2005-2007 and another from 2007-2010, combined with medical record review, were searched. The older dataset did not include the International Classification of Diagnoses (ICD) diagnosis code for osteonecrosis of the jaw (ONJ; ICD 733.45). Incidence rates and relative risks were estimated using Cox regression. RESULTS: The literature review produced nine studies of varying quality. The incidence rates for BONJ among osteoporosis patients varied from 0.028 % to 4.3 %. Two prior studies estimated the relative risk of ONJ related to bisphosphonates and found odds ratios of 7.2 and 9.2. Our attempts to estimate the incidence rate of BONJ encompassed 41,957 in the dataset from 2005-2007 and 466,645 in a separate dataset from 2007-2010. From the older dataset, we found 51 potential cases of BONJ using a broad definition of possible ONJ. One case was confirmed by a dentist for a prevalence of 0.02 % (95 % CI 0.004 %-0.11 %) among bisphosphonate users. From the newer dataset, we found 13 possible cases, but none could be confirmed. Most subjects with the ONJ diagnosis code appeared to have had an osteoporosis-related fracture and not ONJ. CONCLUSIONS: The literature suggests a broad range of possible values for the prevalence of BONJ; our estimate fell within the range from prior literature.


Assuntos
Osteonecrose da Arcada Osseodentária Associada a Difosfonatos/epidemiologia , Osteonecrose da Arcada Osseodentária Associada a Difosfonatos/etiologia , Conservadores da Densidade Óssea/efeitos adversos , Conservadores da Densidade Óssea/uso terapêutico , Estudos de Coortes , Difosfonatos/efeitos adversos , Difosfonatos/uso terapêutico , Humanos , Incidência , Osteoporose/tratamento farmacológico
11.
Magn Reson Med ; 46(6): 1216-22, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11746589

RESUMO

An inductively coupled, chronically implanted short-solenoid coil was used to obtain in vivo localized 1H NMR spectra and diffusion-weighted images from a rat spinal cord. A 5 x 8 mm two-turn elliptically shaped solenoid coil was implanted in rats at the site of a T-12 vertebral-level laminectomy. Excitation was achieved solely by a 3 x 3 cm external surface coil, and signal detection was achieved by inductively coupling the external coil to the implanted coil. The image signal-to-noise ratio (SNR) obtained with the inductively-coupled implanted coil was compared with that obtained using a linear or a quadrature external surface coil. The implanted coil provided a gain by over a factor of 3 in SNR. The implanted coil was used to measure localized 1H spectra in vivo at the T13/L1 spinal-cord level within a 1.85 x 1.85 x 4.82 mm (16.5 microL) volume. With 256 averages, a approximately 3-s repetition delay and respiratory gating, a high-quality spectrum was acquired in 13 min. In addition, water translational diffusion was measured in three orthogonal directions using a stimulated-echo imaging sequence, with a short echo time (TE), to produce a quantitative map of diffusion in a rat spinal cord in vivo.


Assuntos
Imageamento por Ressonância Magnética , Espectroscopia de Ressonância Magnética , Medula Espinal/anatomia & histologia , Medula Espinal/metabolismo , Animais , Feminino , Imageamento por Ressonância Magnética/instrumentação , Espectroscopia de Ressonância Magnética/instrumentação , Imagens de Fantasmas , Ratos , Ratos Sprague-Dawley
13.
EMBO J ; 19(14): 3597-607, 2000 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-10899114

RESUMO

Inhibitor-of-apoptosis proteins (IAPs), including neuronal apoptosis inhibitory protein (NAIP), inhibit cell death. Other IAPs inhibit key caspase proteases which effect cell death, but the mechanism by which NAIP acts is unknown. Here we report that NAIP, through its third baculovirus inhibitory repeat domain (BIR3), binds the neuron-restricted calcium-binding protein, hippocalcin, in an interaction promoted by calcium. In neuronal cell lines NSC-34 and Neuro-2a, over-expression of the BIR domains of NAIP (NAIP-BIR1-3) counteracted the calcium-induced cell death induced by ionomycin and thapsigargin. This protective capacity was significantly enhanced when NAIP-BIR1-3 was co-expressed with hippocalcin. Over-expression of the BIR3 domain or hippocalcin alone did not substantially enhance cell survival, but co-expression greatly increased their protective effects. These data suggest synergy between NAIP and hippocalcin in facilitating neuronal survival against calcium-induced death stimuli mediated through the BIR3 domain. Analysis of caspase activity after thapsigargin treatment revealed that caspase-3 is activated in NSC-34, but not Neuro-2a, cells. Thus NAIP, in conjunction with hippocalcin, can protect neurons against calcium-induced cell death in caspase-3-activated and non-activated pathways.


Assuntos
Apoptose/efeitos dos fármacos , Proteínas de Ligação ao Cálcio/metabolismo , Cálcio/farmacologia , Caspases/metabolismo , Neurônios Motores/citologia , Proteínas do Tecido Nervoso/metabolismo , Animais , Animais Recém-Nascidos , Cálcio/antagonistas & inibidores , Proteínas de Ligação ao Cálcio/genética , Caspase 3 , Inibidores de Caspase , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Hipocalcina , Humanos , Hibridização In Situ , Neurônios Motores/efeitos dos fármacos , Neurônios Motores/enzimologia , Neurônios Motores/metabolismo , Proteínas do Tecido Nervoso/química , Proteínas do Tecido Nervoso/genética , Proteína Inibidora de Apoptose Neuronal , Ligação Proteica/efeitos dos fármacos , Estrutura Terciária de Proteína , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Medula Espinal/metabolismo , Estaurosporina/farmacologia , Tapsigargina/farmacologia , Transfecção , Técnicas do Sistema de Duplo-Híbrido
14.
Cancer Res ; 60(1): 8-12, 2000 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-10646842

RESUMO

Nasopharyngeal carcinoma (NPC) is an endemic cancer in southern China and northern Africa, and its pathogenesis is not yet well defined at the molecular level. Although the involvement of p53 and of the retinoblastoma gene (RB/p105) in NPC has been well studied, there is paucity of mutational data regarding the retinoblastoma-related gene RB2/p130 in primary tumors and particularly in NPC. We have shown previously that RB2/p130 could be rearranged in a nasopharyngeal cell line. In the present study, we screened by single-strand conformation polymorphism and sequence analysis the retinoblastoma-related gene RB2/p130 for mutations within exons 19-22. Mutations in the RB2/p130 gene were detected in 3 of 10 primary human NPCs from Northern Africa (30%). These findings, along with previous data showing that genetic replacement of RB2/p130 restores a normal growth pathway in the nasopharyngeal cell line Hone-1, strengthen the hypothesis that genetic changes of RB2/p130 may be involved in the development and/or progression of nasopharyngeal cancer and suggest that RB2/p130 could be considered a tumor suppressor gene and may be a candidate for novel gene therapeutic approaches for NPC.


Assuntos
Mutação da Fase de Leitura , Genes do Retinoblastoma/genética , Neoplasias Nasofaríngeas/genética , Proteína do Retinoblastoma/genética , Análise Mutacional de DNA , DNA de Neoplasias/genética , Humanos , Reação em Cadeia da Polimerase , Polimorfismo Conformacional de Fita Simples
15.
J Biol Chem ; 274(51): 36288-92, 1999 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-10593918

RESUMO

The ERM protein family members ezrin, radixin, and moesin are cytoskeletal effector proteins linking actin to membrane-bound proteins at the cell surface. Here we report on the cloning of myosin regulatory light chain interacting protein (MIR), a protein with an ERM-homology domain and a carboxyl-terminal RING finger, that is expressed, among other tissues, in brain. MIR is distributed in cultured COS cells, in a punctuated manner as shown using enhanced green fluorescent protein (EGFP)-tagged MIR and by staining with a specific antibody for MIR. In the yeast two-hybrid system and in transfected COS cells, MIR interacts with myosin regulatory light chain B, which in turn regulates the activity of the actomyosin complex. Overexpression of MIR cDNA in PC12 cells abrogated neurite outgrowth induced by nerve growth factor (NGF) without affecting TrkA signaling. The results show that MIR, a novel ERM-like protein, affects cytoskeleton interactions regulating cell motility, such as neurite outgrowth.


Assuntos
Proteínas de Transporte/genética , Cadeias Leves de Miosina/fisiologia , Proteínas do Tecido Nervoso/fisiologia , Neuritos/fisiologia , Neurônios/fisiologia , Sequência de Aminoácidos , Animais , Diferenciação Celular/fisiologia , Clonagem Molecular , DNA Complementar/genética , DNA Complementar/isolamento & purificação , Humanos , Dados de Sequência Molecular , Neuritos/ultraestrutura , Neurônios/ultraestrutura , Células PC12 , Ratos , Alinhamento de Sequência , Ubiquitina-Proteína Ligases
16.
Br J Pharmacol ; 125(5): 953-62, 1998 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9846632

RESUMO

1. Effects of the synthetic vitamin D analogue EB1089 on indices of apoptosis in cultured human breast cancer cells and in nitrosomethylurea-induced rat mammary tumours in vivo were investigated. 2. At a dose of 0.5 microg kg(-1) body weight, EB1089 caused significant inhibition of tumour progression over the 28 day treatment period in the absence of a significant increase in serum calcium concentration. Higher doses of EB1089 (1 and 2.5 microg kg(-1)) produced substantial regression of the experimental tumours which was accompanied by a striking change in the histological appearance of tumours consistent with induction of tumour cell death. 3. Fragmentation of genomic DNA is a characteristic feature of apoptosis. With the terminal transferase (TdT) assay, 3' DNA breaks indicative of DNA fragmentation were detected histochemically in mammary tumour cells from animals treated with EB1089 (2.5 microg kg(-1)) for 14 days. 4. Effects of the vitamin D analogue on induction of apoptosis were examined in vitro using the MCF-7 human breast cancer cell line. Using the TUNEL method, positive nuclear staining indicative of DNA fragmentation was detected in cells treated for 4 days with 10 nM EB1089. Apoptosis was also quantitated using a cell death ELISA which revealed a time and dose dependent induction of apoptosis by EB1089. 5. The effects of EB1089 on the expression of two oncoproteins which may regulate apoptosis, bcl-2 and bax were examined by Western analysis. In MCF-7 cell cultures treated with 1,25(OH)2D3 or EB1089 (1 x 10(-8) M), bcl-2 protein levels were decreased in a time-dependent manner relative to control levels. In contrast bax protein was not markedly regulated by these compounds. Densitometric analyses indicate that the vitamin D compounds lower the bcl-2/bax ratio favouring increased susceptibility of MCF-7 cells to undergo apoptosis. 6. These results suggest that the synthetic vitamin D analogue EB1089 may promote tumour regression by inducing active cell death.


Assuntos
Antineoplásicos/farmacologia , Apoptose , Calcitriol/análogos & derivados , Neoplasias Mamárias Experimentais/tratamento farmacológico , Animais , Antineoplásicos/uso terapêutico , Calcitriol/farmacologia , Calcitriol/uso terapêutico , Fragmentação do DNA , Feminino , Expressão Gênica/efeitos dos fármacos , Humanos , Neoplasias Mamárias Experimentais/patologia , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas c-bcl-2/genética , Ratos , Células Tumorais Cultivadas , Vitamina D/análogos & derivados , Vitamina D/farmacologia , Proteína X Associada a bcl-2
17.
Curr Biol ; 8(11): 665-8, 1998 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-9635195

RESUMO

The mouse midbrain-hindbrain constriction is centrally involved in patterning of the midbrain and anterior hindbrain (cerebellum), as revealed by recent genetic studies using mice and embryological studies in chick (reviewed in [1,2]). This region can act as an organizer region to induce midbrain and cerebellar development. Genes such as Engrailed-1, Pax-2 and Pax-5, which are expressed in the embryonic cells that will form the midbrain and the cerebellum, are required for development of these regions. Fate-mapping experiments at early somite stages in chick have revealed that the cerebellar primordium is located both anterior and posterior to the midbrain-hindbrain constriction, whereas midbrain precursors lie more anteriorly. Fate mapping in mice has been complicated by the inaccessibility of the postimplantation embryo. Here, we report the use of a new in vivo approach involving the Cre-IoxP site-specific recombination system [3] to map the fate of cells in the mouse midbrain-hindbrain constriction. We show that cells originating in the mouse dorsal midbrain-hindbrain constriction during embryonic days 9-12 contribute significantly to the medial cerebellum and colliculi. Our data demonstrate the feasibility of using a recombinase-based lineage-tracing system for fate mapping in the mouse.


Assuntos
Desenvolvimento Embrionário e Fetal/genética , Mesencéfalo/embriologia , Recombinação Genética , Rombencéfalo/embriologia , Proteínas Virais , Animais , Embrião de Galinha , Cruzamentos Genéticos , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Genes Reporter , Proteínas de Homeodomínio/genética , Integrases/genética , Óperon Lac , Masculino , Camundongos , Camundongos Transgênicos , Proteínas do Tecido Nervoso/genética , Gravidez
18.
Biochemistry ; 37(6): 1640-5, 1998 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-9484235

RESUMO

Fast inactivation is restored in inactivation deletion mutant voltage-gated potassium (Kv) channels by application of synthetic inactivation 'ball' peptide. Using Fourier transform infrared and circular dichroism spectroscopy, we have investigated the structure of synthetic Kv3.4 channel ball peptide, in a range of environments relevant to the function of the ball domain. The ball peptide contains no alpha-helix or beta-sheet in reducing conditions in aqueous solution, but when cosolubilized with anionic lipid or detergent in order to mimic the environment which the ball domain encounters during channel inactivation, the ball peptide adopts a partial beta-sheet structure. Oxidation of the Kv3.4 ball peptide facilitates formation of a disulfide bond between Cys6 and Cys24 and adoption of a partial beta-sheet structure in aqueous solution; the tendency of the oxidized ball peptide to adopt beta-sheet is generally greater than that of the reduced ball peptide in a given environment. THREADER modeling of the Kv3.4 ball peptide structure predicts a beta-hairpin-like conformation which corresponds well to the structure suggested by spectroscopic analysis of the ball peptide in its cyclic arrangement. A V7E mutant Kv3.4 ball peptide analogue of the noninactivating Shaker B L7E mutant ball peptide cannot adopt beta-structure whatever the environment, and regardless of oxidation state. The results suggest that the Kv3.4 ball domain undergoes a conformational change during channel inactivation and may implicate a novel regulatory role for intramolecular disulfide bond formation in the Kv3.4 ball domain in vivo.


Assuntos
Ativação do Canal Iônico , Peptídeos/antagonistas & inibidores , Bloqueadores dos Canais de Potássio , Canais de Potássio/química , Conformação Proteica , Sequência de Aminoácidos , Substituição de Aminoácidos/genética , Dicroísmo Circular , Humanos , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Peptídeos/síntese química , Peptídeos/genética , Canais de Potássio/genética , Espectroscopia de Infravermelho com Transformada de Fourier
19.
Artigo em Inglês | MEDLINE | ID: mdl-11367461

RESUMO

AIDS: Home Safe Home is a residential living program for homeless HIV-positive youth between the ages of 16 and 22. The program director, Erik Mercer, describes how the program provides these teens with a home, a safe place where they can learn the skills needed to transition from living on the streets to being self-supporting and independent. The program includes vocational training groups, substance abuse counseling, and basic living skills lessons on cooking and managing money. Clients are referred from a variety of other New York programs or may refer themselves. The group is diverse and includes gay, lesbian, or transgender individuals. Some clients attend outside meetings for alcohol or drug treatment, and there is an emphasis on making life choices to reduce the risk of harm.^ieng


Assuntos
Infecções por HIV , Jovens em Situação de Rua , Instituições Residenciais , Adolescente , Serviços de Saúde do Adolescente , Adulto , Humanos , Cidade de Nova Iorque
20.
Biochim Biophys Acta ; 1341(1): 71-8, 1997 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-9300810

RESUMO

The recombinant N-terminal fragment (amino acids 14-162) of a tetrameric voltage-gated potassium channel (K(V)1.1) has been studied using spectroscopic techniques. Evidence is presented that it forms a tetramer in aqueous solution, whereas when solubilised in 1% Triton X-100 it remains monomeric. The secondary structure content of both monomeric and tetrameric K(V)1.1 N-terminal fragment has been estimated from FTIR and CD spectroscopy to be 20-25% alpha-helix, 20-25% beta-sheet, 20% turns and 30-40% random coil. Solubilisation of the protein in detergent is shown by hydrogen-deuterium exchange analysis to alter tertiary structure rather than secondary structure and this may be the determining factor in tetramerisation ability. Using molecular modelling we propose a supersecondary structure consisting of two structural domains.


Assuntos
Canais de Potássio de Abertura Dependente da Tensão da Membrana , Canais de Potássio/química , Estrutura Secundária de Proteína , Sequência de Aminoácidos , Dicroísmo Circular , Clonagem Molecular , Citoplasma/química , Canal de Potássio Kv1.1 , Dados de Sequência Molecular , Octoxinol , Proteínas Recombinantes/química , Espectroscopia de Infravermelho com Transformada de Fourier
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