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1.
Epidemiol Psychiatr Sci ; 30: e39, 2021 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-34044906

RESUMO

AIMS: Bipolar disorder is associated with premature mortality, but evidence is mostly derived from Western countries. There has been no research evaluating shortened lifespan in bipolar disorder using life-years lost (LYLs), which is a recently developed mortality metric taking into account illness onset for life expectancy estimation. The current study aimed to examine the extent of premature mortality in bipolar disorder patients relative to the general population in Hong Kong (HK) in terms of standardised mortality ratio (SMR) and excess LYLs, and changes of mortality rate over time. METHODS: This population-based cohort study investigated excess mortality in 12 556 bipolar disorder patients between 2008 and 2018, by estimating all-cause and cause-specific SMRs, and LYLs. Trends in annual SMRs over the 11-year study period were assessed. Study data were retrieved from a territory-wide medical-record database of HK public healthcare services. RESULTS: Patients had higher all-cause [SMR: 2.60 (95% CI: 2.45-2.76)], natural-cause [SMR: 1.90 (95% CI: 1.76-2.05)] and unnatural-cause [SMR: 8.63 (95% CI: 7.34-10.03)] mortality rates than the general population. Respiratory diseases, cardiovascular diseases and cancers accounted for the majority of deaths. Men and women with bipolar disorder had 6.78 (95% CI: 6.00-7.84) years and 7.35 (95% CI: 6.75-8.06) years of excess LYLs, respectively. The overall mortality gap remained similar over time, albeit slightly improved in men with bipolar disorder. CONCLUSIONS: Bipolar disorder is associated with increased premature mortality and substantially reduced lifespan in a predominantly Chinese population, with excess deaths mainly attributed to natural causes. Persistent mortality gap underscores an urgent need for targeted interventions to improve physical health of patients with bipolar disorder.


Assuntos
Transtorno Bipolar , Transtorno Bipolar/epidemiologia , Causas de Morte , Estudos de Coortes , Feminino , Hong Kong/epidemiologia , Humanos , Expectativa de Vida , Masculino
3.
Adv Exp Med Biol ; 1232: 155-168, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31893406

RESUMO

The success of treatment for malignancies, especially those undergoing radiation therapy or chemotherapy, has long been recognized to depend on the degree of hypoxia in the tumor. In addition to the prognostic value of knowing the tumor's initial level of hypoxia, assessing the tumor oxygenation during standard therapy or oxygen-related treatments (such as breathing oxygen-enriched gas mixtures or taking drugs that can increase oxygen supply to tissues) can provide valuable data to improve the efficacy of treatments. A series of early clinical studies of tumors in humans are ongoing at Dartmouth and Emory using electron paramagnetic resonance (EPR) oximetry to assess tumor oxygenation, initially and over time during either natural disease progression or treatment. This approach has the potential for reaching the long-sought goal of enhancing the effectiveness of cancer therapy. In order to effectively reach this goal, we consider the validity of the practical and statistical assumptions when interpreting the measurements made in vivo for patients undergoing treatment for cancer.


Assuntos
Neoplasias , Oximetria , Oxigênio , Hipóxia Tumoral , Espectroscopia de Ressonância de Spin Eletrônica , Humanos , Neoplasias/metabolismo , Oxigênio/metabolismo
4.
Psychol Med ; 50(15): 2599-2609, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-31576787

RESUMO

BACKGROUND: Abnormal effort-based decision-making represents a potential mechanism underlying motivational deficits (amotivation) in psychotic disorders. Previous research identified effort allocation impairment in chronic schizophrenia and focused mostly on physical effort modality. No study has investigated cognitive effort allocation in first-episode psychosis (FEP). METHOD: Cognitive effort allocation was examined in 40 FEP patients and 44 demographically-matched healthy controls, using Cognitive Effort-Discounting (COGED) paradigm which quantified participants' willingness to expend cognitive effort in terms of explicit, continuous discounting of monetary rewards based on parametrically-varied cognitive demands (levels N of N-back task). Relationship between reward-discounting and amotivation was investigated. Group differences in reward-magnitude and effort-cost sensitivity, and differential associations of these sensitivity indices with amotivation were explored. RESULTS: Patients displayed significantly greater reward-discounting than controls. In particular, such discounting was most pronounced in patients with high levels of amotivation even when N-back performance and reward base amount were taken into consideration. Moreover, patients exhibited reduced reward-benefit sensitivity and effort-cost sensitivity relative to controls, and that decreased sensitivity to reward-benefit but not effort-cost was correlated with diminished motivation. Reward-discounting and sensitivity indices were generally unrelated to other symptom dimensions, antipsychotic dose and cognitive deficits. CONCLUSION: This study provides the first evidence of cognitive effort-based decision-making impairment in FEP, and indicates that decreased effort expenditure is associated with amotivation. Our findings further suggest that abnormal effort allocation and amotivation might primarily be related to blunted reward valuation. Prospective research is required to clarify the utility of effort-based measures in predicting amotivation and functional outcome in FEP.


Assuntos
Cognição/fisiologia , Motivação/fisiologia , Desempenho Psicomotor/fisiologia , Transtornos Psicóticos/psicologia , Adolescente , Adulto , Antipsicóticos/farmacologia , Estudos de Casos e Controles , Cognição/efeitos dos fármacos , Feminino , Humanos , Masculino , Motivação/efeitos dos fármacos , Desempenho Psicomotor/efeitos dos fármacos , Transtornos Psicóticos/tratamento farmacológico , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/fisiologia , Análise de Regressão , Recompensa , Adulto Jovem
5.
Psychol Med ; 50(12): 2019-2027, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-31451127

RESUMO

BACKGROUND: Better understanding of interplay among symptoms, cognition and functioning in first-episode psychosis (FEP) is crucial to promoting functional recovery. Network analysis is a promising data-driven approach to elucidating complex interactions among psychopathological variables in psychosis, but has not been applied in FEP. METHOD: This study employed network analysis to examine inter-relationships among a wide array of variables encompassing psychopathology, premorbid and onset characteristics, cognition, subjective quality-of-life and psychosocial functioning in 323 adult FEP patients in Hong Kong. Graphical Least Absolute Shrinkage and Selection Operator (LASSO) combined with extended Bayesian information criterion (BIC) model selection was used for network construction. Importance of individual nodes in a generated network was quantified by centrality analyses. RESULTS: Our results showed that amotivation played the most central role and had the strongest associations with other variables in the network, as indexed by node strength. Amotivation and diminished expression displayed differential relationships with other nodes, supporting the validity of two-factor negative symptom structure. Psychosocial functioning was most strongly connected with amotivation and was weakly linked to several other variables. Within cognitive domain, digit span demonstrated the highest centrality and was connected with most of the other cognitive variables. Exploratory analysis revealed no significant gender differences in network structure and global strength. CONCLUSION: Our results suggest the pivotal role of amotivation in psychopathology network of FEP and indicate its critical association with psychosocial functioning. Further research is required to verify the clinical significance of diminished motivation on functional outcome in the early course of psychotic illness.


Assuntos
Apatia/fisiologia , Transtornos Psicóticos/fisiopatologia , Transtornos Psicóticos/psicologia , Adulto , Teorema de Bayes , Cognição , Feminino , Hong Kong , Humanos , Masculino , Pessoa de Meia-Idade , Psicopatologia , Funcionamento Psicossocial
6.
Schizophr Res ; 216: 255-261, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31866077

RESUMO

There has been limited research into the predictive value of basic symptoms and their relationship with other psychopathology in patients identified using the 'ultra high risk' (UHR) for psychosis approach. The current study investigated whether basic symptoms, specifically cognitive disturbances (COGDIS), were associated with a greater risk of transition to psychotic disorder and persistent attenuated psychotic symptoms (APS) at medium term follow-up (mean = 3.4 years) in UHR patients, as well as with general psychopathology at baseline. The sample included 304 UHR participants (mean age = 19.12 years) involved in an international multicenter trial of omega-3 fatty acids. UHR individuals who also met the COGDIS criteria (basic symptoms risk criteria) did not have a greater risk of transition than those who met the UHR criteria alone. However, meeting COGDIS risk criteria was associated with a greater likelihood of meeting the UHR attenuated psychotic symptoms risk group (i.e., having persistent attenuated psychotic symptoms) at 12-month follow-up (odds ratio = 1.85; 95% CI = 1.03, 3.32). Greater severity of cognitive basic symptoms was also independently associated with more severe general psychopathology at study entry. The findings do not support the notion that combined risk identification approaches (UHR and basic symptoms) aid in the identification of individuals at greatest risk of psychosis, although this interpretation is limited by the modest transition to psychosis rate (13%) and the time of follow up. However, the findings indicate that basic symptoms may be a clinically useful marker of more severe general psychopathology in UHR groups and risk for persistent attenuated psychotic symptoms.


Assuntos
Transtornos Psicóticos , Adolescente , Adulto , Humanos , Escalas de Graduação Psiquiátrica , Psicopatologia , Transtornos Psicóticos/diagnóstico , Transtornos Psicóticos/epidemiologia , Fatores de Risco , Adulto Jovem
9.
Soc Psychiatry Psychiatr Epidemiol ; 54(1): 43-50, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30315332

RESUMO

PURPOSE: This study aimed to investigate the effects of media reporting of a homicide committed by a patient with schizophrenia on the knowledge about and stigma regarding psychosis among the general Hong Kong population. The effects of using the term 'schizophrenia (jing-shen-fen-lei)' in the news on the perceptions of the new Chinese term 'psychosis (si-jue-shi-tiao)' were explored. METHODS: Random telephone surveys of the general Hong Kong population were conducted in April 2009 (1 month before the incident) and June 2009 (1 week after the incident). Stigma was measured with the Link's Perceived Discrimination-Devaluation Scale (LPDDS). Knowledge about the symptoms, treatment and belief of dangerousness of psychosis were assessed. The emotional reaction of the public to the news was explored, and its effects on knowledge and stigma were studied. RESULTS: Overall, 1016 and 506 participants completed the two surveys. More participants in the post-incident survey agreed that people with psychosis are dangerous to the public (χ2 = 4.934, p = 0.026). However, no significant differences were observed in the LPDDS scores. Participants who reported a high level of distress related to the news were more likely to perceive people with psychosis as dangerous to the public (χ2 = 6.738, p = 0.009). Women and older people reported greater distress. CONCLUSIONS: These findings suggest that media reporting of violent incidents involving people with schizophrenia increases the public belief in the dangerousness of people with psychosis but not the overall stigma. Further studies of the differential effects of violence reporting on public perceptions about people with psychosis and schizophrenia are warranted.


Assuntos
Homicídio/psicologia , Meios de Comunicação de Massa , Transtornos Psicóticos/psicologia , Psicologia do Esquizofrênico , Estigma Social , Adulto , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Hong Kong , Humanos , Masculino , Terminologia como Assunto
10.
Schizophr Res ; 202: 333-340, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30539771

RESUMO

Considerable research has been conducted seeking risk factors and constructing prediction models for transition to psychosis in individuals at ultra-high risk (UHR). Nearly all such research has only employed baseline predictors, i.e. data collected at the baseline time point, even though longitudinal data on relevant measures such as psychopathology have often been collected at various time points. Dynamic prediction, which is the updating of prediction at a post-baseline assessment using baseline and longitudinal data accumulated up to that assessment, has not been utilized in the UHR context. This study explored the use of dynamic prediction and determined if it could enhance the prediction of frank psychosis onset in UHR individuals. An emerging statistical methodology called joint modelling was used to implement the dynamic prediction. Data from the NEURAPRO study (n = 304 UHR individuals), an intervention study with transition to psychosis study as the primary outcome, were used to investigate dynamic predictors. Compared with the conventional approach of using only baseline predictors, dynamic prediction using joint modelling showed significantly better sensitivity, specificity and likelihood ratios. As dynamic prediction can provide an up-to-date prediction for each individual at each new assessment post entry, it can be a useful tool to help clinicians adjust their prognostic judgements based on the unfolding clinical symptomatology of the patients. This study has shown that a dynamic approach to psychosis prediction using joint modelling has the potential to aid clinicians in making decisions about the provision of timely and personalized treatment to patients concerned.


Assuntos
Progressão da Doença , Modelos Estatísticos , Transtornos Psicóticos/diagnóstico , Adolescente , Adulto , Ácidos Graxos Ômega-3/farmacologia , Feminino , Seguimentos , Humanos , Masculino , Prognóstico , Transtornos Psicóticos/tratamento farmacológico , Adulto Jovem
11.
NPJ Schizophr ; 4(1): 11, 2018 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-29941938

RESUMO

This study reports a medium-term follow-up of a randomised, double-blind, placebo-controlled trial of omega-3 polyunsaturated fatty acids (PUFA) in ultra-high risk for psychosis (UHR) patients. Primary outcomes of interest were transition to psychosis and symptomatic and functional outcome. A secondary aim was to investigate clinical predictors of medium-term outcome. Three hundred four UHR participants were recruited across 10 specialised early psychosis services in Australia, Asia, and Europe. The intervention consisted of 1.4 g/daily of omega-3 PUFA or placebo, plus up to 20 sessions of cognitive-behavioural case management (CBCM), over the 6-month study period, with participants receiving further CBCM sessions on basis of need between months 6-12. Mean time to follow-up was 3.4 (median = 3.3; SD = 0.9) years. There was a modest increase in transitions between 12-month and medium-term follow-up (11-13%) and substantial improvement in symptoms and functioning between baseline and follow-up, with no differences between the treatment groups. Most improvement had been achieved by end of the intervention. 55% of the sample received mental health treatment between end of intervention and follow-up. Omega-3 PUFA did not provide additional benefits to good quality psychosocial intervention over the medium term. Although most improvement had been achieved by end of intervention the substantial rates of post-intervention mental health service use indicate longer-term clinical need in UHR patients. The post-intervention phase treatment or the longer-term effect of CBCM, or a combination of the two, may have contributed to maintaining the gains achieved during the intervention phase and prevented significant deterioration after this time.

14.
J Mater Chem B ; 5(8): 1574-1584, 2017 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-28736613

RESUMO

Biocompatibility is a major concern for developing biomaterials used in medical devices, tissue engineering and drug delivery. Poly(lactic-co-glycolic acid) (PLGA) is one of the most widely used biodegradable materials, yet still triggers a significant foreign body response that impairs healing. Immune cells including macrophages respond to the implanted biomaterial and mediate the host response, which can eventually lead to device failure. Previously in our laboratory, we found that CD200, an immunomodulatory protein, suppressed macrophage inflammatory activation in vitro and reduced local immune cell infiltration around a biomaterial implant. While in our initial study we used polystyrene as a model material, here we investigate the effect of CD200 on PLGA, a commonly used biomaterial with many potential clinical applications. We fabricated PLGA with varied geometries, modified their surfaces with CD200, and examined macrophage cytokine secretion and phagocytosis. We found that CD200 suppressed secretion of the pro-inflammatory cytokine TNF-α and enhanced secretion of the anti-inflammatory cytokine IL-10, suggesting a role for CD200 in promoting wound healing and tissue remodeling. In addition, we found that CD200 increased phagocytosis in both murine macrophages and human monocytes. Together, these data suggest that modification with CD200 leads to a response that simultaneously prevents inflammation and enhances phagocytosis. This immunomodulatory feature may be used as a strategy to mitigate inflammation or deliver drugs or anti-inflammatory agents targeting macrophages.

15.
Eur Psychiatry ; 41: 37-41, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28049079

RESUMO

BACKGROUND: Amotivation is prevalent in first-episode psychosis (FEP) patients and is a major determinant of functional outcome. Prediction of amotivation in the early stage of psychosis, however, is under-studied. We aimed to prospectively examine predictors of amotivation in FEP patients in a randomized-controlled trial comparing a 1-year extension of early intervention (Extended EI, 3-year EI) with step-down psychiatric care (SC, 2-year EI). METHODS: One hundred sixty Chinese patents were recruited from a specialized EI program for FEP in Hong Kong after they have completed this 2-year EI service, randomly allocated to Extended EI or SC, and followed up for 12 months. Assessments on premorbid adjustment, onset profiles, baseline symptom severity and treatment characteristics were conducted. Data analysis was based on 156 subjects who completed follow-up assessments. RESULTS: Amotivation at 12-month follow-up was associated with premorbid adjustment, allocated treatment condition, and levels of positive symptoms, disorganization, amotivation, diminished expression (DE) and depression at study intake. Hierarchical multiple regression analysis revealed that Extended EI and lower levels of DE independently predicted better outcome on 12-month amotivation. CONCLUSION: Our findings indicate a potentially critical therapeutic role of an extended specialized EI on alleviating motivational impairment in FEP patients. The longer-term effect of Extended EI on amotivation merits further investigation.


Assuntos
Apatia , Intervenção Médica Precoce/métodos , Motivação , Transtornos Psicóticos , Adolescente , Adulto , Depressão/diagnóstico , Cuidado Periódico , Feminino , Seguimentos , Hong Kong , Humanos , Masculino , Análise Multivariada , Gravidade do Paciente , Prognóstico , Escalas de Graduação Psiquiátrica , Técnicas Psicológicas , Psicoterapia/métodos , Transtornos Psicóticos/diagnóstico , Transtornos Psicóticos/psicologia , Transtornos Psicóticos/terapia , Resultado do Tratamento
16.
Psychol Med ; 47(4): 755-765, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27869058

RESUMO

BACKGROUND: Better understanding of the complex interplay among key determinants of functional outcome is crucial to promoting recovery in psychotic disorders. However, this is understudied in the early course of illness. We aimed to examine the relationships among negative symptoms, neurocognition, general self-efficacy and global functioning in first-episode psychosis (FEP) patients using structural equation modeling (SEM). METHOD: Three hundred and twenty-one Chinese patients aged 26-55 years presenting with FEP to an early intervention program in Hong Kong were recruited. Assessments encompassing symptom profiles, functioning, perceived general self-efficacy and a battery of neurocognitive tests were conducted. Negative symptom measurement was subdivided into amotivation and diminished expression (DE) domain scores based on the ratings in the Scale for the Assessment of Negative Symptoms. RESULTS: An initial SEM model showed no significant association between functioning and DE which was removed from further analysis. A final trimmed model yielded very good model fit (χ2 = 15.48, p = 0.63; comparative fit index = 1.00; root mean square error of approximation <0.001) and demonstrated that amotivation, neurocognition and general self-efficacy had a direct effect on global functioning. Amotivation was also found to mediate a significant indirect effect of neurocognition and general self-efficacy on functioning. Neurocognition was not significantly related to general self-efficacy. CONCLUSION: Our results indicate a critical intermediary role of amotivation in linking neurocognitive impairment to functioning in FEP. General self-efficacy may represent a promising treatment target for improvement of motivational deficits and functional outcome in the early illness stage.


Assuntos
Apatia/fisiologia , Modelos Estatísticos , Motivação/fisiologia , Transtornos Psicóticos/fisiopatologia , Autoeficácia , Adulto , Feminino , Hong Kong/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Transtornos Psicóticos/diagnóstico , Transtornos Psicóticos/epidemiologia
17.
Psychol Med ; 47(4): 703-717, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27852348

RESUMO

BACKGROUND: Early weak treatment response is one of the few trans-diagnostic, treatment-agnostic predictors of poor outcome following a full treatment course. We sought to improve the outcome of clients with weak initial response to guided self-help cognitive behavior therapy (GSH). METHOD: One hundred and nine women with binge-eating disorder (BED) or bulimia nervosa (BN) (DSM-IV-TR) received 4 weeks of GSH. Based on their response, they were grouped into: (1) early strong responders who continued GSH (cGSH), and early weak responders randomized to (2) dialectical behavior therapy (DBT), or (3) individual and additional group cognitive behavior therapy (CBT+). RESULTS: Baseline objective binge-eating-day (OBD) frequency was similar between DBT, CBT+ and cGSH. During treatment, OBD frequency reduction was significantly slower in DBT and CBT+ relative to cGSH. Relative to cGSH, OBD frequency was significantly greater at the end of DBT (d = 0.27) and CBT+ (d = 0.31) although these effects were small and within-treatment effects from baseline were large (d = 1.41, 0.95, 1.11, respectively). OBD improvements significantly diminished in all groups during 12 months follow-up but were significantly better sustained in DBT relative to cGSH (d = -0.43). At 6- and 12-month follow-up assessments, DBT, CBT and cGSH did not differ in OBD. CONCLUSIONS: Early weak response to GSH may be overcome by additional intensive treatment. Evidence was insufficient to support superiority of either DBT or CBT+ for early weak responders relative to early strong responders in cGSH; both were helpful. Future studies using adaptive designs are needed to assess the use of early response to efficiently deliver care to large heterogeneous client groups.


Assuntos
Terapia Comportamental/métodos , Transtorno da Compulsão Alimentar/terapia , Bulimia Nervosa/terapia , Avaliação de Resultados em Cuidados de Saúde , Adulto , Terapia Cognitivo-Comportamental/métodos , Feminino , Humanos , Pessoa de Meia-Idade , Adulto Jovem
18.
Soc Psychiatry Psychiatr Epidemiol ; 52(3): 259-267, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-27909775

RESUMO

PURPOSE: Public stigma is an important barrier to the recovery of patients with psychosis. The current study aimed to investigate the change in stigma towards psychosis and knowledge about psychosis between 2009 and 2014 among the Chinese population in Hong Kong, with a specific focus on gender role. METHODS: Random telephone survey of general population in Hong Kong was conducted in 2009 and 2014. Stigma was measured with the revised Link's Perceived Discrimination-Devaluation Scale (LPDDS). Logistic regression was used to explore the effect of time on the change of knowledge of psychosis, and linear regression was used to explore the effect of time on the change of stigma. Change of knowledge and stigma based on gender was specifically explored. RESULTS: In total, 1016 and 1018 subjects completed the survey in 2009 and 2014, respectively. Significantly, more people agreed with medication treatment for psychosis and fewer people had misunderstanding about psychosis. However, there was no significant change in stigma levels. Males were found to have a significant deterioration of stigma (B = 0.099, SE = 0.033, ß = 0.100, p = 0.003) but not females. Significantly, more males endorsed medication treatment for psychosis (χ 2 = 5.850, df = 1, p = 0.016) but no change for females (χ 2 = 1.401, df = 1, p = 0.238). CONCLUSIONS: Results of this study suggested that there was an improvement in the biological understanding of psychosis but no change of public stigma within the Hong Kong Chinese population. The specific role of gender in relation to stigma and level of knowledge about psychosis indicates that this should be a consideration in designing future anti-stigma campaigns.


Assuntos
Conhecimentos, Atitudes e Prática em Saúde/etnologia , Transtornos Psicóticos/psicologia , Estigma Social , Adolescente , Adulto , Idoso , Feminino , Hong Kong/etnologia , Humanos , Masculino , Pessoa de Meia-Idade , Fatores Sexuais , Adulto Jovem
19.
J Fish Biol ; 90(4): 1257-1264, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27873320

RESUMO

Adult chum salmon Oncorhynchus keta homing behaviour in a two-choice test tank (Y-maze) was monitored using a passive integrated transponder (PIT)-tag system in response to river-specific dissolved free amino-acid (DFAA) profiles and revealed that the majority of O. keta showed a preference for artificial natal-stream water and tended to stay in this maze arm for a longer period; natal-stream water was chosen over a nearby tributary's water, but not when the O. keta were presented with a non-tributary water. The results demonstrate the ability of O. keta to discriminate artificial stream waters containing natural levels of DFAA.


Assuntos
Aminoácidos/farmacologia , Comportamento de Retorno ao Território Vital/efeitos dos fármacos , Oncorhynchus keta/fisiologia , Rios/química , Aminoácidos/química , Animais
20.
Adv Exp Med Biol ; 923: 351-357, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27526163

RESUMO

We have incorporated LiNc-BuO, an oxygen-sensing paramagnetic material, in polydimethylsiloxane (PDMS), which is an oxygen-permeable, biocompatible, and stable polymer. We fabricated implantable and retrievable oxygen-sensing chips (40 % LiNc-BuO in PDMS) using a 20-G Teflon tubing to mold the chips into variable shapes and sizes for in vivo studies in rats. In vitro EPR measurements were used to test the chip's oxygen response. Oxygen induced linear and reproducible line broadening with increasing partial pressure (pO2). The oxygen response was similar to that of bare (unencapsulated) crystals and did not change significantly on sterilization by autoclaving. The chips were implanted in rat femoris muscle and EPR oximetry was performed repeatedly (weekly) for 12 weeks post-implantation. The measurements showed good reliability and reproducibility over the period of testing. These results demonstrated that the new formulation of OxyChip with 40 % LiNc-BuO will enable the applicability of EPR oximetry for long-term measurement of oxygen concentration in tissues and has the potential for clinical applications.


Assuntos
Técnicas Biossensoriais , Dimetilpolisiloxanos/química , Espectroscopia de Ressonância de Spin Eletrônica , Metaloporfirinas/química , Músculo Esquelético/metabolismo , Oximetria/métodos , Consumo de Oxigênio , Oxigênio/metabolismo , Animais , Cristalização , Masculino , Miniaturização , Pressão Parcial , Ratos Wistar , Reprodutibilidade dos Testes , Fatores de Tempo
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