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1.
Pediatr Rheumatol Online J ; 21(1): 111, 2023 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-37798784

RESUMO

BACKGROUND: This paper presents insight into the scale of mental health concerns for families who have a child or young person with a diagnosis of Juvenile Idiopathic Arthritis (JIA) living in any of the four nations of the United Kingdom (UK). The study's objective is to share the current experiences of those that responded to a charity survey and consider future work to improve mental health support. METHODS: This work was initiated and led by five UK charity partner organisations working with families affected by JIA. Parents/carers of a child or young person with JIA, and young people with JIA, submitted self-completion online questionnaires. The questionnaire asked 19 core questions, with a focus on the mental health impact of having and living with a JIA diagnosis. Questionnaires were delivered via charity partner UK-wide mailing lists and social media. RESULTS: Questionnaire were completed by 291 participants over a 3-week period in February 2022. The majority of respondents were parents (229, 79%), 103 children had been diagnosed for over six years (35%), and 131 (45%) received shared care between paediatric rheumatology centres. In total, 168 (59%) children and young people with JIA had received, were currently receiving or were waiting for mental health support. Parents reported that their child's diagnosis impacted their own mental health (218, 82%). Children and young people reported never being offered mental health support during appointments for JIA (157, 54%), and 71 (50%) of these had never received support. CONCLUSION: Children and young people with JIA have significant mental health sequelae from their diagnosis. Our findings found that nearly 60% of our respondents have had or are requiring mental health support, with significant numbers of parents/carers reporting difficulties in accessing care for their child's mental health or their own mental health, due to their child's diagnosis. This unique collaborative charity-led study, illustrates the importance of timely and accessible mental health support. Further work is needed to understand why best practice guidance for mental health support is not being met consistently and to identify how to embed it into standard rheumatology care.


Assuntos
Artrite Juvenil , Humanos , Criança , Adolescente , Artrite Juvenil/psicologia , Instituições de Caridade , Pais/psicologia , Inquéritos e Questionários , Nível de Saúde
2.
Mult Scler Relat Disord ; 68: 104121, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36088727

RESUMO

BACKGROUND: Following the outbreak of COVID-19, global healthcare systems have had to rapidly adapt. People with multiple sclerosis (pwMS) were required to make decisions about their individual risk and consequent work and social behaviors. This study aimed to evaluate risk perception and patterns of shielding behavior amongst pwMS at the onset of the COVID-19 pandemic and the subsequent impact on patients' employment and access to disease modifying therapies (DMTs). METHODS: Postal surveys were sent to 1690 people within a UK population-based MS cohort during the first wave of the COVID-19 pandemic. Patients were surveyed on: (i) perceived vulnerability to COVID-19; (ii) isolation behavior; (iii) interruption to DMT; (iv) employment status; (v) level of satisfaction with their current working arrangement. RESULTS: Responses were received from 1000 pwMS. Two thirds of patients reported isolating at home during the first wave of the pandemic. This behavior was associated with increased age (p<0.0001), higher disability (p<0.0001) and use of high-efficacy DMTs (p = 0.02). The majority of patients reported feeling vulnerable (82%) with perceived vulnerability associated with higher EDSS (p<0.0001) and receiving a high-efficacy DMT (p = 0.04). Clinician-defined risk was associated with shielding behavior, with those at high-risk more likely to self-isolate/shield (p<0.0001). Patients on high-efficacy DMTs were more likely to have an interruption to their treatment (50%) during the first wave of the pandemic. Most pwMS experienced a change to their working environment, and most were satisfied with the adjustments. CONCLUSION: This study highlights the risk perception, social behavioral practices and changes to treatment experienced by pwMS during the first wave of the COVID-19 pandemic in a large, well-described UK cohort. The results may help inform management of pwMS during future pandemic waves.


Assuntos
COVID-19 , Esclerose Múltipla , Humanos , COVID-19/complicações , Esclerose Múltipla/tratamento farmacológico , Esclerose Múltipla/epidemiologia , Esclerose Múltipla/complicações , Pandemias , Atenção à Saúde , Percepção
3.
Hum Reprod ; 36(2): 367-380, 2021 01 25.
Artigo em Inglês | MEDLINE | ID: mdl-33355349

RESUMO

STUDY QUESTION: Are there phase-specific changes in the early secretory (ES) phase human tubal lavage proteome that can inform and potentially optimize IVF culture media? SUMMARY ANSWER: The human tubal lavage proteome during the ES phase relative to the menstrual phase reveals substantial differential protein abundance in pathways such as glycolysis, redox homeostasis and activation of 14-3-3 zeta-mediated signaling. WHAT IS KNOWN ALREADY: The Fallopian tube is uniquely suited to the development of the preimplantation embryo as it transits the tube during the ES phase of the menstrual cycle. Euploid cleavage-stage embryo arrest may reflect incomplete recapitulation of in-vivo conditions by current media formulations. STUDY DESIGN, SIZE, DURATION: Proteome-wide analysis of distal tubal lavage specimens collected from 26 healthy women undergoing open microtubal anastomosis surgery from January 2013 to January 2018 was performed. Specimens were grouped by menstrual cycle phase in order to analyze phase-specific differences in protein abundance. For the murine embryo assay, single-cell embryos (N = 482) were collected from superovulated wild type C57BL/6 female mice and cultured in microdrops over 5 days for the assessment of blastocyst development. PARTICIPANTS/MATERIALS, SETTING, METHODS: Human tubal lavage specimens were processed for label-free mass spectrometry. Reported menstrual cycle day was confirmed by measuring serum hormones. Key protein targets in the ES phase were validated via immunoblot. The ES phase-specific increase in 14-3-3 zeta protein was confirmed via ELISA of conditioned media obtained from primary human Fallopian tube epithelial cell culture. A murine embryo assay was performed to investigate the impact of graduated concentrations of 14-3-3 zeta on the blastocyst development rate. MAIN RESULTS AND THE ROLE OF CHANCE: Comparison of the ES and menstrual phase human tubal lavage proteomes revealed 74 differentially expressed proteins with enrichment of pathways and biological processes involved in the regulation of carbohydrate metabolism, oxidative stress and cell survival. The adapter-regulator protein 14-3-3 zeta was among the most significantly increased in the ES phase. Supplementation of embryo culture media with 14-3-3 zeta at concentrations tested did not significantly improve the murine blastocyst development. LIMITATIONS, REASONS FOR CAUTION: Although select associations were recapitulated in the conditioned media from sex steroid exposed primary human tubal epithelial cells, cell culture represents an in-vitro approximation. Changes to embryo culture media, such as protein supplementation, must undergo rigorous preclinical safety testing prior to adoption for human use. WIDER IMPLICATIONS OF THE FINDINGS: This study represents the first description of the human Fallopian tube lavage proteome across the menstrual cycle, revealing a unique proteomic signature during the ES phase. Although supplementation of culture media with 14-3-3 zeta at appropriate concentrations showed no significant impact on the murine blastocyst development rate, other biologically plausible candidate proteins for individual or high throughput testing strategies are identified. STUDY FUNDING/COMPETING INTEREST(S): This work was funded in part by an Army Medical Department Advanced Medical Technology Initiative grant from the United States Army Medical Research and Materiel Command's Telemedicine and Advanced Technology Research Center. There are no competing interests. TRIAL REGISTRATION NUMBER: N/A.


Assuntos
Tubas Uterinas , Proteoma , Animais , Blastocisto , Técnicas de Cultura Embrionária , Feminino , Fertilização in vitro , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Proteômica , Irrigação Terapêutica
4.
Trans R Soc Trop Med Hyg ; 94(3): 295-8, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10975004

RESUMO

The acute-phase response to infection alters the plasma concentrations of most biochemical measures of iron status, rendering assessment of status difficult. Soluble transferrin receptors (TfR) may be an exception but have not been examined longitudinally during the major metabolic and inflammatory changes which occur during clinical malaria. Blood samples were collected daily during hospitalization, and again at a follow-up 2-6 weeks after discharge, from adult, mainly European, patients (n = 49) who developed uncomplicated Plasmodium falciparum malaria following visits to endemic areas. Parasitaemia and plasma concentrations of ferritin, TfR, C-reactive protein (CRP), alpha 1-acid glycoprotein (AGP) and alpha 1-antichymotrypsin (ACT) were measured. The concentrations of CRP, AGP and ACT correlated highly (P < 0.001) with each other and with plasma ferritin, and were significantly higher (P < 0.05) at all time points in hospital compared to the follow-up. TfR concentration correlated negatively and significantly (P < 0.05) with AGP and CRP but not with ACT or ferritin, and was significantly lower (around 30%) at all time points in hospital compared to follow-up, although in only 1 subject did it ever fall outside the normal reference range. In areas where both iron deficiency and clinical episodes of malaria are common, plasma TfR values need to be interpreted cautiously as indicators of iron status.


Assuntos
Malária Falciparum/sangue , Transferrina/análise , Adulto , Proteína C-Reativa/análise , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Orosomucoide/análise , Receptores da Transferrina/metabolismo , alfa 1-Antiquimotripsina/sangue
6.
Int J Biochem ; 24(4): 579-84, 1992 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-1355451

RESUMO

1. Experiments were carried out to examine the biochemical changes, such as contractile protein biochemistry and membrane bound enzyme alterations associated with skeletal muscles of myd/myd. 2. Our studies demonstrate that there was a progressive decline in myofibrillar ATPase activity, and this decrease is greatest in 30 weeks old animals of myd/myd as compared to controls. 3. The proteolytic activity of myofibrils isolated from myd/myd was significantly higher than controls. 4. There was no significant difference in Ca2+ ATPase activity of myosin and actin-activated myosin ATPase activity of myd/myd and their controls. 5. Mg2+ ATPase and Na(+)+K(+)-ATPase of myodystrophic SL showed significant increase compared to controls. 6. Isoproterenol stimulated adenylate cyclase activity was significantly lower in the SL of dystrophic mice compared to controls. 7. GTP+isoproterenol stimulate adenylate cyclase was significantly higher in control SL and SR when compared to SL and SR isolated from myd/myd. 8. Guanylate cyclase activity was greater in myodystrophic mice both in the absence and presence of Triton X-100. cGMP and cAMP phosphodiesterase activities were greater in dystrophic mice as compared to controls. 9. These observations suggest that there are significant changes in myofibrillar ATPase, myofibrillar protease and membrane bound enzymes of myd/myd compared to control.


Assuntos
Músculos/enzimologia , Distrofia Muscular Animal/enzimologia , Miofibrilas/enzimologia , Adenosina Trifosfatases/metabolismo , Adenilil Ciclases/metabolismo , Animais , Caseínas/metabolismo , Guanilato Ciclase/metabolismo , Membranas/enzimologia , Camundongos , Músculos/ultraestrutura , Diester Fosfórico Hidrolases/metabolismo , Sarcolema/enzimologia , Retículo Sarcoplasmático/enzimologia
7.
Biochem Med Metab Biol ; 44(3): 259-65, 1990 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-2149642

RESUMO

Ethanol consumption is known to affect cardiac and skeletal muscle. In vivo experiments on cardiac muscle showed that ethanol affects cardiac contractility and Vmax, suggesting that contractile proteins of the myocardium were affected by ethanol. Therefore, experiments were carried out to examine the effects of ethanol on the cardiac contractile protein ATPase activities. Cardiac myofibrils isolated from ethanol-fed hamsters showed a significant decrease in myofibrillar ATPase activities between pCa 6 and 4. On the other hand, addition of ethanol (0.1%) in vitro to cardiac myofibrils from control hamster had no significant effect on the ATPase activities, suggesting that hamsters need to be exposed for longer periods of time to induce demonstratable changes in the contractile protein ATPase activity. Actin-activated myosin ATPase activities were significantly lower in myofibrils from ethanol-fed hamsters at 1:1 and 1:2 ratios of myosin to actin. These investigations revealed that chronic (4 weeks) exposure of hamsters to ethanol reduced cardiac contractile protein ATPase activity, which may help explain impaired cardiac function in chronic alcoholics.


Assuntos
Adenosina Trifosfatases/metabolismo , Alcoolismo/enzimologia , Etanol/toxicidade , Miocárdio/enzimologia , Alcoolismo/fisiopatologia , Animais , Cricetinae , Feminino , Mesocricetus , Contração Miocárdica/efeitos dos fármacos , Miofibrilas/efeitos dos fármacos , Miofibrilas/enzimologia
8.
Toxicol Appl Pharmacol ; 94(3): 407-13, 1988 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-3261055

RESUMO

These experiments were designed to determine whether skinned skeletal muscle fibers could be useful in screening new antidotes to organophosphorus poisons. Isometric force and fiber diameter were measured in mechanically skinned fibers from mice and frogs. Fibers were depleted of calcium and placed in a calcium loading solution that contained 0.5 mM EGTA with pCa 6.25. The elapsed time (zero time) before a contracture began and the maximum rate of force development (slope) were measured and divided by the square of the diameter (normalized zero time, normalized slope). The zero time was assumed to be the time required for the sarcoplasmic reticulum to attain a threshold concentration for calcium-induced calcium release, and the slope was assumed to indicate primarily the rapidity of the release of calcium from the sarcoplasmic reticulum. Organophosphorus agents, sarin, soman, tabun, and VX were also placed in the loading solutions. Only sarin failed to shorten the normalized zero times of mouse fibers compared to controls, and all agents decreased the normalized slopes. The normalized zero times of frog fibers were not altered by the agents, but the normalized slopes were altered by some agents. Pralidoxime chloride (PAM) and 3-Cl-2,5,6-trimethylbenzoic acid (TBA) were also added to the loading solution for mouse fibers; PAM was marginally effective in moderating some actions of the organophosphates. Because the effects of the agents on the fibers were so definite, we concluded that the skinned muscle fiber might indeed be useful as a screening tool for developing and testing new antidotes to organophosphorus poisons.


Assuntos
Inseticidas/toxicidade , Músculos/efeitos dos fármacos , Compostos Organofosforados , Retículo Sarcoplasmático/efeitos dos fármacos , Animais , Cálcio/metabolismo , Técnicas In Vitro , Masculino , Camundongos , Compostos de Pralidoxima/farmacologia , Rana pipiens
10.
Dig Dis Sci ; 31(9): 987-92, 1986 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-2426066

RESUMO

Brush border membrane vesicles from hamster jejunum were used to investigate the effects of ethanol on Na+-dependent transport of amino acids. Imposition of an inwardly directed gradient of NaCl resulted in transient accumulation of L-alanine and L-phenylalanine, followed by a gradual decline to equilibrium levels. Ethanol reduced both the rate of uptake and the maximum accumulation of these amino acids without altering the final equilibrium level. The inhibitory effects of ethanol on L-alanine uptake were dose dependent and reversible. On the other hand, ethanol had no effect on the rate of uptake of L-alanine or the final equilibrium level attained when vesicles were incubated with a KCl gradient or when NaCl was equilibrated across the vesicle membrane. These results suggest that ethanol does not inhibit Na+-dependent uptake of neutral amino acids by direct inhibition of the Na+-dependent transport systems for these solutes.


Assuntos
Alanina/metabolismo , Etanol/farmacologia , Microvilosidades/efeitos dos fármacos , Fenilalanina/metabolismo , Sódio/metabolismo , Animais , Cricetinae , Técnicas In Vitro , Canais Iônicos/efeitos dos fármacos , Microvilosidades/metabolismo
11.
Ann Ophthalmol ; 18(6): 216-9, 222, 1986 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-3729230

RESUMO

The question of whether or not phacoemulsification causes significant corneal endothelial damage has been studied in many ways. In this study, we used videotaped specular microscopy and nitroblue tetrazolium (NBT) staining to assess cell damage under conditions in which the two most commonly blamed sources of damage--probe tip trauma and lens fragments--cannot be implicated. After 15 minutes of irrigation, aspiration, and ultrasound in a modified corneal viewing and storage (CVS) chamber, the four test corneas showed less than 5% cell damage as assessed by NBT staining, which was no more than in the control. In one case, an unexpected air bubble on the endothelium caused a loss of endothelial cells. Because small air bubbles are common during phacoemulsification, and because such air bubbles may represent a cause of endothelial cell loss, the endothelial damage caused by air bubbles during phacoemulsification merits further study.


Assuntos
Extração de Catarata/métodos , Córnea/patologia , Adulto , Lâmina Limitante Posterior/patologia , Endotélio/patologia , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Fatores de Tempo
12.
J Nutr Sci Vitaminol (Tokyo) ; 30(3): 209-20, 1984 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-6436453

RESUMO

Isolated ileal enterocytes incubated with intrinsic factor-[57Co]vitamin B12 (IF-B12) at 37 degrees C took up 25 times more B12 than jejunal enterocytes. Uptake of B12 by ileal cells was dependent upon IF and Ca2+. B12 taken up by ileal enterocytes could be separated into two components: 1) B12 which was retained (E component) and 2) released (R-E component) by chelation of divalent cations. The E component could be removed from ileal cells by treatment with Triton X-100. Incubation of ileal enterocytes at 22 degrees C or with 2,4-dinitrophenol reduced incorporation of B12 into the E, but not the R-E, component. Ileal enterocytes were incubated with IF-[57Co]B12 washed and reincubated with unlabeled IF-B12. Reincubation resulted in a decrease in the amount of [57Co]B12 in the R-E component and a concomitant increase of that in the E component indicating that B12 was transferred from the R-E to the E component. Dinitrophenol reduced transfer from R-E to E components. These results suggest that, using isolated enterocytes, two sequential steps in ileal absorption of B12 can be identified: 1) energy-independent binding of IF-B12 to its receptor on the brush border followed by 2) an energy-dependent event which probably represents transfer of B12 from its receptor into the cell.


Assuntos
Íleo/metabolismo , Vitamina B 12/metabolismo , 2,4-Dinitrofenol , Animais , Cálcio/metabolismo , Cricetinae , Dinitrofenóis/farmacologia , Ácido Edético/farmacologia , Feminino , Glucose/farmacologia , Concentração de Íons de Hidrogênio , Técnicas In Vitro , Absorção Intestinal/efeitos dos fármacos , Fator Intrínseco/metabolismo , Jejuno/metabolismo , Microvilosidades/metabolismo , Octoxinol , Ouabaína/farmacologia , Polietilenoglicóis/farmacologia
13.
Biochem J ; 200(2): 225-9, 1981 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-6280680

RESUMO

Brush-border-membrane vesicles isolated from hamster ileum were incubated with either papain or Pronase P and subsequently centrifuged to obtain soluble (supernatant) and insoluble (pellet) fractions. Papain (4 units/ml) solubilized 95--100% of the sucrase and leucine naphthylamide-hydrolysing activities but only 30% of the alkaline phosphatase. Digestion with papain also resulted in the solubilization of more than 75% of the ileal receptor for intrinsic factor-vitamin B-12 complex with a corresponding decrease in receptor activity in the pellet. Essentially 100% of the receptor activity was recovered. In contrast, digestion with Pronase P resulted in a decrease in total receptor activity. Papain-solubilized receptor was not sedimented by centrifugation at 105 000 g for 90 min and was eluted in the included volume of Sepharose 6B. Like the binding to more intact preparations, binding of intrinsic factor-vitamin B-12 complex to papain-solubilized receptor was rapid, reaching 50% of maximum in 8 min, and required Ca2+. Although Mg2+ could not completely substitute for Ca2+, Mg2+ did stimulate Ca2+-dependent binding at low Ca2+ concentrations. These results demonstrate that the ileal receptor for intrinsic factor-vitamin B-12 complex can be solubilized with papain, and suggest that papain solubilization may be a useful first step in the isolation and purification of this receptor.


Assuntos
Íleo/metabolismo , Fator Intrínseco/metabolismo , Papaína/farmacologia , Receptores de Superfície Celular/metabolismo , Receptores de Peptídeos , Vitamina B 12/metabolismo , Animais , Cálcio/farmacologia , Cricetinae , Íleo/efeitos dos fármacos , Substâncias Macromoleculares , Microvilosidades/efeitos dos fármacos , Microvilosidades/metabolismo , Receptores de Superfície Celular/isolamento & purificação , Solubilidade
14.
Am J Physiol ; 239(6): G452-6, 1980 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-7446737

RESUMO

Brush-border membrane vesicles from hamster intestine were employed to investigate uptake (binding) of vitamin B12 (B12). Ileal vesicles took up 25 times more B12 than did jejunal vesicles. Uptake of B12 by ileal vesicles was dependent on intrinsic factor (IF) and required Ca2+. Increasing the Ca2+ concentration caused an increase in uptake of B12 reaching a maximum at approximately 8 mM Ca2+. At high Ca2+ concentrations, 6-8 mM, Mg2+ had little effect on uptake of B12. At low Ca2+ concentrations, up to 2 mM, Mg2+ stimulated B12 uptake. Mg2+, Mn2+, and, to a lesser extent, Sr2+ stimulated Ca2+-dependent B12 uptake, but Zn2+, Ba2+, Na+, K+, and La3+ did not. B12 was apparently not metabolized and was bound as IF-B12 complex, which could be removed with (ethylenedinitrilo)tetraacetic acid (EDTA). Our results suggest that two types of divalent cation reactive sites are involved in binding of IF-B12. One is Ca2+ specific. The other is less specific reacting with Mg2+, Mn2+, Sr2+, and perhaps Ca2+ itself, thereby stimulating Ca2+-dependent binding of IF-B12 to its ileal receptor.


Assuntos
Cátions Bivalentes/farmacologia , Membrana Celular/metabolismo , Mucosa Intestinal/metabolismo , Microvilosidades/metabolismo , Vitamina B 12/metabolismo , Animais , Cálcio/farmacologia , Cricetinae , Íleo/metabolismo , Absorção Intestinal/efeitos dos fármacos , Jejuno/metabolismo , Magnésio/farmacologia , Manganês/farmacologia
15.
Biochem J ; 190(3): 731-6, 1980 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-7470076

RESUMO

The effects of bile salts on Na+-coupled accumulation of D-glucose and L-alanine by brush-border-membrane vesicles isolated from hamster jejunum were investigated. The approximate percentage inhibition of Na+-coupled D-glucose accumulation produced by various bile salts at a concentration of 1 mM were: deoxycholate and chenodeoxycholate, 60%; glycine and taurine conjugates of deoxycholate and chenodeoxycholate, 40--50%; lithocholate, 45%; cholate and its glycine and taurine conjugates, less than 10%. Inhibition of Na+-coupled accumulation of D-glucose was rapid, reversible and not due to dissolution of the vesicles. Na+-coupled accumulation of L-alanine was also inhibited by deoxycholate. Deoxycholate but not cholate enhanced (1) the rate of Na+ influx, (2) the rate of influx of D-glucose and L-alanine in the absence of a Na+ gradient and (3) the rate of efflux of D-glucose and L-alanine from vesicles preloaded with this sugar or amino acid. Deoxycholate-stimulated efflux of D-glucose was not blocked by phlorizin, which completely prevented efflux in the absence of this bile salt. These results suggest that selected bile salts inhibit Na+-coupled accumulation of D-glucose and L-alanine by enhancing the rate of dissipation of the Na+ gradient required for substrate accumulation. In addition, bile salts may also decrease D-glucose and L-alanine accumulation by increasing the rate of efflux of these substrates across the brush-border plasma membrane.


Assuntos
Alanina/metabolismo , Ácidos e Sais Biliares/farmacologia , Membrana Celular/metabolismo , Glucose/metabolismo , Jejuno/metabolismo , Microvilosidades/metabolismo , Sódio/metabolismo , Animais , Permeabilidade da Membrana Celular/efeitos dos fármacos , Cricetinae , Técnicas In Vitro , Absorção Intestinal/efeitos dos fármacos , Jejuno/efeitos dos fármacos , Microvilosidades/efeitos dos fármacos
16.
Biochem J ; 178(2): 299-303, 1979 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-444217

RESUMO

The uptake of taurocholate was studied in membrane vesicles isolated from brush borders of hamster jejunum and ileum. When an extra- to intra-vesicular gradient of Na+ ions was present ileal vesicles took up 10 times more taurocholate than did jejunal vesicles. Accumulation of taurocholate by ileal vesicles was transient and was due to transport of this bile salt into an osmotically active intravesicular space rather than simple binding. Uptake of taurocholate was specifically dependent on Na+ ions; NaCl and Na2SO4 were capable of supporting accumulation, whereas KCl, LiCl and mannitol were not. Na+-coupled uptake of taurocholate into ileal vesicles was inhibited by other trihydroxy bile salts, by preloading the vesicles with Na+ and by simultaneous flow of glucose into the vesicles. Similarly, vesicular uptake of glucose was inhibited by simultaneous uptake of taurocholate. These results demonstrated that brush-border membrane vesicles prepared from ileum possess an Na+-coupled co-transport system for taurocholate that is similar to the active bile-salt transport system present in the intact ileum.


Assuntos
Membrana Celular/metabolismo , Íleo/metabolismo , Microvilosidades/metabolismo , Sódio/metabolismo , Ácido Taurocólico/metabolismo , Animais , Transporte Biológico/efeitos dos fármacos , Ácidos Cólicos/farmacologia , Cricetinae , Glucose/metabolismo , Ácido Glicocólico/farmacologia , Íleo/ultraestrutura , Técnicas In Vitro , Absorção Intestinal , Jejuno/metabolismo , Jejuno/ultraestrutura , Concentração Osmolar
17.
Gastroenterology ; 69(1): 175-89, 1975 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-238896

RESUMO

Microsomal fractions from homogenates of pig gastric fundic mucosa showed high levels of K+-stimulated adenosine triphosphatase (ATPase) and K+-stimulated phosphatase. Similar preparations from antral mucosa showed virtually no such activity. Because of mitochondrial contamination the fundic microsomes were further separated by sucrose density gradient centrifugation. A low density band of membranes (peak 1.12 to 1.13 g per ml) possessed all of the K+-stimulated enzyme activities. Morphological features and the abundant glycoproteins of the low density microsomes suggested they might be derived from the tubulovesicles of oxyntic cells. Mitochondrial and ribosomal markers were associated with membranes with much higher densities (greater than 1.22). The K+-stimulated ATPase has a pH optimum of 7.5 and required Mg++, but neither Na+ nor ouabain had any appreciable effect on the activity. Stimulation of basal ATPase by K+ ranged from 1.5 to 3.0-fold with an apparent Ka for activation between 0.2 to 0.4 mM K+. Addition of various K+ ionophoretic substances (e.g., gramicidin) produced further stimulation of K+-ATPase up to 6 times the basal rate. The mean activities for seven separate preparations of purified low density pig fundic microsomes were as follows (micromoles of ATP hydrolyzed per mg protein per hr +/- SEM); basal ATPase, 15.8 +/- 2.8; plus 10 mM K+, 29.3 +/- 4.5; plus 10 mM K+ and 10(-5) M gramicidin, 45.2 +/- 5.2. Neither the basal ATPase nor the K+-stimulated rates were altered by HCO3- or Cl-. The occurrence of these active and unique enzyme activities in the oxyntic region of gastric mucosa suggest some relation with secretory activity. Possible functional roles are discussed.


Assuntos
4-Nitrofenilfosfatase , Adenosina Trifosfatases , Mucosa Gástrica/enzimologia , Microssomos/enzimologia , Monoéster Fosfórico Hidrolases , Potássio/farmacologia , 4-Nitrofenilfosfatase/metabolismo , Acetatos/farmacologia , Adenosina Trifosfatases/metabolismo , Animais , Bicarbonatos/farmacologia , Centrifugação com Gradiente de Concentração , Cloretos/farmacologia , Ativação Enzimática/efeitos dos fármacos , Mucosa Gástrica/ultraestrutura , Concentração de Íons de Hidrogênio , Iontoforese , Magnésio/farmacologia , Mitocôndrias/enzimologia , Ouabaína/farmacologia , Antro Pilórico/enzimologia , Ribossomos/enzimologia , Sódio/farmacologia , Estimulação Química , Estômago/citologia , Suínos
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