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1.
Sci Adv ; 7(17)2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33893093

RESUMO

Existing three-dimensional (3D) culture techniques are limited by trade-offs between throughput, capacity for high-resolution imaging in living state, and geometric control. Here, we introduce a modular microscale hanging drop culture where simple design elements allow high replicates for drug screening, direct on-chip real-time or high-resolution confocal microscopy, and geometric control in 3D. Thousands of spheroids can be formed on our microchip in a single step and without any selective pressure from specific matrices. Microchip cultures from human LN229 glioblastoma and patient-derived mouse xenograft cells retained genomic alterations of originating tumors based on mate pair sequencing. We measured response to drugs over time with real-time microscopy on-chip. Last, by engineering droplets to form predetermined geometric shapes, we were able to manipulate the geometry of cultured cell masses. These outcomes can enable broad applications in advancing personalized medicine for cancer and drug discovery, tissue engineering, and stem cell research.

2.
Transplantation ; 105(2): 436-442, 2021 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-32235255

RESUMO

BACKGROUND: Desensitization protocols for HLA-incompatible living donor kidney transplantation (ILDKT) vary across centers. The impact of these, as well as other practice variations, on ILDKT outcomes remains unknown. METHODS: We sought to quantify center-level variation in mortality and graft loss following ILDKT using a 25-center cohort of 1358 ILDKT recipients with linkage to Scientific Registry of Transplant Recipients for accurate outcome ascertainment. We used multilevel Cox regression with shared frailty to determine the variation in post-ILDKT outcomes attributable to between-center differences and to identify any center-level characteristics associated with improved post-ILDKT outcomes. RESULTS: After adjusting for patient-level characteristics, only 6 centers (24%) had lower mortality and 1 (4%) had higher mortality than average. Similarly, only 5 centers (20%) had higher graft loss and 2 had lower graft loss than average. Only 4.7% of the differences in mortality (P < 0.01) and 4.4% of the differences in graft loss (P < 0.01) were attributable to between-center variation. These translated to a median hazard ratio of 1.36 for mortality and 1.34 of graft loss for similar candidates at different centers. Post-ILDKT outcomes were not associated with the following center-level characteristics: ILDKT volume and transplanting a higher proportion of highly sensitized, prior transplant, preemptive, or minority candidates. CONCLUSIONS: Unlike most aspects of transplantation in which center-level variation and volume impact outcomes, we did not find substantial evidence for this in ILDKT. Our findings support the continued practice of ILDKT across these diverse centers.


Assuntos
Rejeição de Enxerto/prevenção & controle , Sobrevivência de Enxerto/efeitos dos fármacos , Antígenos HLA/imunologia , Disparidades em Assistência à Saúde , Histocompatibilidade , Imunossupressores/uso terapêutico , Isoanticorpos/sangue , Transplante de Rim , Doadores Vivos , Padrões de Prática Médica , Adulto , Feminino , Rejeição de Enxerto/sangue , Rejeição de Enxerto/imunologia , Rejeição de Enxerto/mortalidade , Humanos , Imunossupressores/efeitos adversos , Transplante de Rim/efeitos adversos , Transplante de Rim/mortalidade , Masculino , Pessoa de Meia-Idade , Indicadores de Qualidade em Assistência à Saúde , Sistema de Registros , Medição de Risco , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento , Estados Unidos
3.
Am J Transplant ; 21(4): 1612-1621, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33370502

RESUMO

Incompatible living donor kidney transplant recipients (ILDKTr) have pre-existing donor-specific antibody (DSA) that, despite desensitization, may persist or reappear with resulting consequences, including delayed graft function (DGF) and acute rejection (AR). To quantify the risk of DGF and AR in ILDKT and downstream effects, we compared 1406 ILDKTr to 17 542 compatible LDKT recipients (CLDKTr) using a 25-center cohort with novel SRTR linkage. We characterized DSA strength as positive Luminex, negative flow crossmatch (PLNF); positive flow, negative cytotoxic crossmatch (PFNC); or positive cytotoxic crossmatch (PCC). DGF occurred in 3.1% of CLDKT, 3.5% of PLNF, 5.7% of PFNC, and 7.6% of PCC recipients, which translated to higher DGF for PCC recipients (aOR = 1.03 1.682.72 ). However, the impact of DGF on mortality and DCGF risk was no higher for ILDKT than CLDKT (p interaction > .1). AR developed in 8.4% of CLDKT, 18.2% of PLNF, 21.3% of PFNC, and 21.7% of PCC recipients, which translated to higher AR (aOR PLNF = 1.45 2.093.02 ; PFNC = 1.67 2.403.46 ; PCC = 1.48 2.243.37 ). Although the impact of AR on mortality was no higher for ILDKT than CLDKT (p interaction = .1), its impact on DCGF risk was less consequential for ILDKT (aHR = 1.34 1.621.95 ) than CLDKT (aHR = 1.96 2.292.67 ) (p interaction = .004). Providers should consider these risks during preoperative counseling, and strategies to mitigate them should be considered.


Assuntos
Transplante de Rim , Função Retardada do Enxerto/etiologia , Rejeição de Enxerto/etiologia , Sobrevivência de Enxerto , Humanos , Transplante de Rim/efeitos adversos , Doadores Vivos , Estudos Retrospectivos , Fatores de Risco
4.
Braz. j. biol ; 80(3): 565-573, July-Sept. 2020. tab
Artigo em Inglês | LILACS-Express | LILACS | ID: biblio-1132399

RESUMO

Abstract Due to increased number of herbicide resistant weeds, it is needed to explore the allelopathic potential of plants as an alternative. The research was conducted to investigate allelopathic effects of Carica papaya L. leaf powder and aqueous extract on seeds as well as pre-germinated seeds of Avena fatua L., Helianthus annuus L., Rumex dentatus L., Zea mays L. and Triticum aestivum L. on filter paper and soil in Weed Management Program Laboratory, Department of Plant and Environmental Protection at PARC Institute of Advanced Studies in Agriculture, National Agriculture Research Centre, Islamabad, Pakistan. Germination percentage (%), radicle length (cm) and plumule length (cm) were parameters observed for 'Plant leaf powder bioassay' and 'Aqueous extract method'. Most significant growth inhibition was observed in A. fatua seedlings in filter paper method. A. fatua radicle length was reduced by C. papaya aqueous extract (80%) and leaf powder (89%) bioassays. Plumule length was reduced under the influence of aqueous extract (57-73%) and powdered material (59-77%). The inhibitory effects on other test species were in sequence of H. annuus followed by Z. mays and R. dentatus. The aqueous extract showed non-significant effect on wheat seed germination, radicle and plumule growth. It is suggested that C. papaya aqueous extract can be used as source of weed management in wheat crop.


Resumo Devido ao aumento do número de ervas daninhas resistentes aos herbicidas, é necessário explorar o potencial alelopático das plantas como uma alternativa. A pesquisa foi conduzida com o objetivo de investigar os efeitos alelopáticos do pó foliar de Carica papaya e do extrato aquoso das sementes, bem como das sementes pré-germinadas de Avena fatua, Helianthus annuus, Rumex dentatus, Zea mays e Triticum aestivum em papel de filtro e solo no Laboratório do Programa de Manejo de Ervas Daninhas, Departamento de Plantas e Proteção Ambiental do Instituto PARC de Estudos Avançados em Agricultura, Centro Nacional de Pesquisa Agrícola, Islamabad, Paquistão. A porcentagem de germinação (%), o comprimento radicular e o comprimento da plúmula (cm) foram os parâmetros observados para o 'Bioensaio de Pó de Folha de Planta' e o 'Método de Extração Aquoso'. A maior inibição do crescimento foi observada em mudas de A. fatua no método de papel de filtro. O comprimento radicular de A. fatua foi reduzido com os extratos aquosos de C. papaya (80%) e pó de folhas (89%). O comprimento das plúmulas foi reduzido sob a influência do extrato aquoso (57-73%) e material em pó (59-77%). Os efeitos inibitórios em outras espécies-teste foram na sequência de H. annuus seguido por Z. mays e R. dentatus. O extrato aquoso apresentou efeito não significativo na germinação das sementes de trigo, nos crescimentos radiculares e das plúmulas. Sugere-se que o extrato aquoso de C. papaya pode ser utilizado como fonte de manejo de plantas daninhas na cultura do trigo.

5.
Br Dent J ; 229(3): 151-152, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32811918
6.
APL Bioeng ; 4(2): 026104, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32548540

RESUMO

Three-dimensional (3D) biomimetic systems hold great promise for the study of biological systems in vitro as well as for the development and testing of pharmaceuticals. Here, we test the hypothesis that an intact segment of lumbar rat spinal cord will form functional neuromuscular junctions (NMJs) with engineered, 3D muscle tissue, mimicking the partial development of the peripheral nervous system (PNS). Muscle tissues are grown on a 3D-printed polyethylene glycol (PEG) skeleton where deflection of the backbone due to muscle contraction causes the displacement of the pillar-like "feet." We show that spinal cord explants extend a robust and complex arbor of motor neurons and glia in vitro. We then engineered a "spinobot" by innervating the muscle tissue with an intact segment of lumbar spinal cord that houses the hindlimb locomotor central pattern generator (CPG). Within 7 days of the spinal cord being introduced to the muscle tissue, functional neuromuscular junctions (NMJs) are formed, resulting in the development of an early PNS in vitro. The newly innervated muscles exhibit spontaneous contractions as measured by the displacement of pillars on the PEG skeleton. Upon chemical excitation, the spinal cord-muscle system initiated muscular twitches with a consistent frequency pattern. These sequences of contraction/relaxation suggest the action of a spinal CPG. Chemical inhibition with a blocker of neuronal glutamate receptors effectively blocked contractions. Overall, these data demonstrate that a rat spinal cord is capable of forming functional neuromuscular junctions ex vivo with an engineered muscle tissue at an ontogenetically similar timescale.

7.
bioRxiv ; 2020 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-32511358

RESUMO

The COVID-19 pandemic provides an urgent example where a gap exists between availability of state-of-the-art diagnostics and current needs. As assay details and primer sequences become widely known, many laboratories could perform diagnostic tests using methods such as RT-PCR or isothermal RT-LAMP amplification. A key advantage of RT-LAMP based approaches compared to RT-PCR is that RT-LAMP is known to be robust in detecting targets from unprocessed samples. In addition, RT-LAMP assays are performed at a constant temperature enabling speed, simplicity, and point-of-use testing. Here, we provide the details of an RT-LAMP isothermal assay for the detection of SARS-CoV-2 virus with performance comparable to currently approved tests using RT-PCR. We characterize the assay by introducing swabs in virus spiked synthetic nasal fluids, moving the swab to viral transport medium (VTM), and using a volume of that VTM for performing the amplification without an RNA extraction kit. The assay has a Limit-of-Detection (LOD) of 50 RNA copies/µL in the VTM solution within 20 minutes, and LOD of 5000 RNA copies/µL in the nasal solution. Additionally, we show the utility of this assay for real-time point-of-use testing by demonstrating detection of SARS-CoV-2 virus in less than 40 minutes using an additively manufactured cartridge and a smartphone-based reader. Finally, we explore the speed and cost advantages by comparing the required resources and workflows with RT-PCR. This work could accelerate the development and availability of SARS-CoV-2 diagnostics by proving alternatives to conventional laboratory benchtop tests.

9.
Braz J Biol ; 80(3): 565-573, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31644650

RESUMO

Due to increased number of herbicide resistant weeds, it is needed to explore the allelopathic potential of plants as an alternative. The research was conducted to investigate allelopathic effects of Carica papaya L. leaf powder and aqueous extract on seeds as well as pre-germinated seeds of Avena fatua L., Helianthus annuus L., Rumex dentatus L., Zea mays L. and Triticum aestivum L. on filter paper and soil in Weed Management Program Laboratory, Department of Plant and Environmental Protection at PARC Institute of Advanced Studies in Agriculture, National Agriculture Research Centre, Islamabad, Pakistan. Germination percentage (%), radicle length (cm) and plumule length (cm) were parameters observed for 'Plant leaf powder bioassay' and 'Aqueous extract method'. Most significant growth inhibition was observed in A. fatua seedlings in filter paper method. A. fatua radicle length was reduced by C. papaya aqueous extract (80%) and leaf powder (89%) bioassays. Plumule length was reduced under the influence of aqueous extract (57-73%) and powdered material (59-77%). The inhibitory effects on other test species were in sequence of H. annuus followed by Z. mays and R. dentatus. The aqueous extract showed non-significant effect on wheat seed germination, radicle and plumule growth. It is suggested that C. papaya aqueous extract can be used as source of weed management in wheat crop.


Assuntos
Carica , Germinação , Paquistão , Extratos Vegetais , Folhas de Planta , Sementes
10.
Int J Surg Case Rep ; 77: 467-471, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33395827

RESUMO

INTRODUCTION: Heterotopic ossification (HO) is the abnormal bone formation in soft tissue where bone normally does not exist. HO can occur secondary to musculoskeletal trauma, burns, spinal cord injury, or traumatic head injury. The treatment of HO ranges from simple medical treatment to advance surgical intervention; it is largely dependent on the amount of bone formation, the location, the limitation of motion, and the severity of the joint disease. PRESENTATION OF CASE: We present the case of a 26-year-old man who presented to an orthopedic clinic with pain in the lower back and both knees, which was not relieved by conservative treatment. The clinical examination revealed a loss of motion in both hips. Radiography of the pelvis showed bilateral fused hips and Brooker type IV HO in both hips. The patient underwent HO resection and converted the fused hip to total hip arthroplasty (THA) through a direct lateral approach. The patient was satisfied with the outcome of over 18 months of follow-up. DISCUSSION: A direct lateral approach, as what we performed, is a simple approach that can expose the acetabulum and proximal femur. The presence of intraoperative fluoroscopy can help identify HO's extension with less damage to the soft tissue and blood loss. CONCLUSION: The surgery appears to be a doable, effective, and safe procedure to treat fused bilateral hip with HO. This is the first study to report staged bilateral THA for HO through a direct lateral approach to the best of our knowledge.

11.
Lab Chip ; 18(8): 1231-1240, 2018 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-29564463

RESUMO

Sepsis, as a leading cause of death worldwide, relies on systemic inflammatory response syndrome (SIRS) criteria for its diagnosis. SIRS is highly non-specific as it relies on monitoring of patients' vitals for sepsis diagnosis, which are known to change with many confounding factors. Changes in leukocyte counts and CD64 expression levels are known specific biomarkers of pro-inflammatory host response at the onset of sepsis. Recently, we have developed a biosensor chip that can enumerate the leukocyte counts and quantify the neutrophil CD64 expression levels from a drop of blood. We were able to show improved sepsis diagnosis and prognosis in clinical studies by measuring these parameters during different times of the patients' stay in hospital. In this paper, we investigated the rate of cell capture with CD64 expression levels and used this in a multivariate computational model using artificial neural networks (ANNs) and showed improved accuracy of quantifying CD64 expression levels from the biosensor (n = 106 whole blood experiments). We found a high coefficient of determination and low error between biosensor- and flow cytometry-based neutrophil CD64 expression levels using multiple ANN training methods in comparison to those of univariate regression commonly employed. This approach can find many applications in biosensor data analytics by utilizing multiple features of the biosensor's data for output determination.


Assuntos
Técnicas Biossensoriais/instrumentação , Contagem de Leucócitos/instrumentação , Técnicas Analíticas Microfluídicas/instrumentação , Receptores de IgG/sangue , Sepse/diagnóstico , Desenho de Equipamento , Humanos , Contagem de Leucócitos/métodos , Análise Multivariada , Redes Neurais de Computação
12.
Nat Commun ; 9(1): 202, 2018 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-29335461

RESUMO

Here, we present a technique that performs on-chip picoliter real-time reverse transcriptase loop mediated isothermal amplification (RT-LAMP) reactions on a histological tissue section without any analyte purification while preserving the native spatial location of the nucleic acid molecules. We demonstrate this method by amplifying TOP2A messenger RNA (mRNA) in a prostate cancer xenograft with 100 µm spatial resolution and by visualizing the variation in threshold time of amplification across the tissue. The on-chip reaction was validated by mRNA fluorescence in situ hybridization (mFISH) from cells in the tissue section. The entire process, from tissue loading on microchip to results from RT-LAMP can be carried out in less than 2 h. We anticipate that this technique, with its ease of use, fast turnaround, and quantitative molecular outputs, would become an invaluable tissue analysis tool for researchers and clinicians in the biomedical arena.


Assuntos
Perfilação da Expressão Gênica , Neoplasias da Próstata/genética , Animais , Linhagem Celular Tumoral , DNA Topoisomerases Tipo II/genética , Xenoenxertos , Humanos , Hibridização in Situ Fluorescente , Masculino , Camundongos , Camundongos Nus , Procedimentos Analíticos em Microchip , Proteínas de Ligação a Poli-ADP-Ribose/genética , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo Real , Reprodutibilidade dos Testes , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Espectroscopia de Infravermelho com Transformada de Fourier
13.
Am J Transplant ; 18(3): 650-658, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-28834181

RESUMO

Thirty percent of kidney transplant recipients are readmitted in the first month posttransplantation. Those with donor-specific antibody requiring desensitization and incompatible live donor kidney transplantation (ILDKT) constitute a unique subpopulation that might be at higher readmission risk. Drawing on a 22-center cohort, 379 ILDKTs with Medicare primary insurance were matched to compatible transplant-matched controls and to waitlist-only matched controls on panel reactive antibody, age, blood group, renal replacement time, prior kidney transplantation, race, gender, diabetes, and transplant date/waitlisting date. Readmission risk was determined using multilevel, mixed-effects Poisson regression. In the first month, ILDKTs had a 1.28-fold higher readmission risk than compatible controls (95% confidence interval [CI] 1.13-1.46; P < .001). Risk peaked at 6-12 months (relative risk [RR] 1.67, 95% CI 1.49-1.87; P < .001), attenuating by 24-36 months (RR 1.24, 95% CI 1.10-1.40; P < .001). ILDKTs had a 5.86-fold higher readmission risk (95% CI 4.96-6.92; P < .001) in the first month compared to waitlist-only controls. At 12-24 (RR 0.85, 95% CI 0.77-0.95; P = .002) and 24-36 months (RR 0.74, 95% CI 0.66-0.84; P < .001), ILDKTs had a lower risk than waitlist-only controls. These findings of ILDKTs having a higher readmission risk than compatible controls, but a lower readmission risk after the first year than waitlist-only controls should be considered in regulatory/payment schemas and planning clinical care.


Assuntos
Incompatibilidade de Grupos Sanguíneos/imunologia , Antígenos HLA/imunologia , Falência Renal Crônica/cirurgia , Transplante de Rim/métodos , Doadores Vivos/provisão & distribuição , Readmissão do Paciente/estatística & dados numéricos , Complicações Pós-Operatórias , Adulto , Estudos de Casos e Controles , Feminino , Seguimentos , Taxa de Filtração Glomerular , Sobrevivência de Enxerto , Hospitalização/estatística & dados numéricos , Humanos , Isoanticorpos/sangue , Isoanticorpos/imunologia , Testes de Função Renal , Masculino , Pessoa de Meia-Idade , Prognóstico , Fatores de Risco
14.
Nat Biomed Eng ; 2(9): 640-648, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-31015684

RESUMO

Point-of-care sensors that enable the fast collection of information relevant to a patient's health state can facilitate improved health access, reduce healthcare costs and improve the quality of healthcare delivery. In the diagnosis of sepsis - defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection, and the leading cause of in-patient death and of hospital readmission in the United States - predicting which infections will lead to life-threatening organ dysfunction and developing specific anti-sepsis treatments remain challenging because of the significant heterogeneity of the host response. Yet the use of point-of-care devices could reduce the time from the onset of a patient's infection to the administration of appropriate therapeutics. In this Perspective, we describe the current state of point-of-care sensors for the diagnosis and monitoring of sepsis, and outline opportunities in the use of these devices to dramatically improve patient care.


Assuntos
Assistência ao Paciente/métodos , Sepse/tratamento farmacológico , Humanos , Sistemas Automatizados de Assistência Junto ao Leito
15.
Biomed Microdevices ; 19(4): 73, 2017 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-28831630

RESUMO

Infectious diseases remain the world's top contributors to death and disability, and, with recent outbreaks of Zika virus infections there has been an urgency for simple, sensitive and easily translatable point-of-care tests. Here we demonstrate a novel point-of-care platform to diagnose infectious diseases from whole blood samples. A microfluidic platform performs minimal sample processing in a user-friendly diagnostics card followed by real-time reverse-transcription loop-mediated isothermal amplification (RT-LAMP) on the same card with pre-dried primers specific to viral targets. Our point-of-care platform uses a commercial smartphone to acquire real-time images of the amplification reaction and displays a visual read-out of the assay. We apply this system to detect closely related Zika, Dengue (types 1 and 3) and Chikungunya virus infections from whole blood on the same pre-printed chip with high specificity and clinically relevant sensitivity. Limit of detection of 1.56e5 PFU/mL of Zika virus from whole blood was achieved through our platform. With the ability to quantitate the target nucleic acid, this platform can also perform point-of-care patient surveillance for pathogen load or select biomarkers in whole blood.


Assuntos
Febre de Chikungunya , Dengue , Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/métodos , Técnicas de Amplificação de Ácido Nucleico , Sistemas Automatizados de Assistência Junto ao Leito , Smartphone , Infecção por Zika virus , Febre de Chikungunya/sangue , Febre de Chikungunya/diagnóstico , Vírus Chikungunya , Dengue/sangue , Dengue/diagnóstico , Vírus da Dengue , Humanos , Técnicas de Amplificação de Ácido Nucleico/instrumentação , Técnicas de Amplificação de Ácido Nucleico/métodos , Zika virus , Infecção por Zika virus/sangue , Infecção por Zika virus/diagnóstico
16.
Nat Commun ; 8: 15949, 2017 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-28671185

RESUMO

Sepsis, a potentially life-threatening complication of an infection, has the highest burden of death and medical expenses in hospitals worldwide. Leukocyte count and CD64 expression on neutrophils (nCD64) are known to correlate strongly with improved sensitivity and specificity of sepsis diagnosis at its onset. A major challenge is the lack of a rapid and accurate point-of-care (PoC) device that can perform these measurements from a minute blood sample. Here, we report a PoC microfluidic biochip to enumerate leukocytes and quantify nCD64 levels from 10 µl of whole blood without any manual processing. Biochip measurements have shown excellent correlation with the results from flow cytometer. In clinical studies, we have used PoC biochip to monitor leukocyte counts and nCD64 levels from patients' blood at different times of their stay in the hospital. Furthermore, we have shown the biochip's utility for improved sepsis diagnosis by combining these measurements with electronic medical record (EMR).


Assuntos
Microfluídica/métodos , Receptores de IgG/sangue , Sepse/sangue , Biomarcadores/sangue , Citometria de Fluxo , Humanos , Contagem de Leucócitos , Microfluídica/instrumentação , Neutrófilos/citologia , Sistemas Automatizados de Assistência Junto ao Leito , Receptores de IgG/genética , Sensibilidade e Especificidade , Sepse/diagnóstico , Sepse/genética
17.
Anal Chim Acta ; 967: 93-101, 2017 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-28390491

RESUMO

High performance liquid chromatography coupled with post column derivatisation (HPLC-PCD) may be used to profile the antioxidant content of a sample. There are, however, drawbacks in the use of HPLC-PCD setups; namely the high volume reaction coils that are typically used lowering the observed separation efficiency. Reaction flow chromatography has the ability to overcome these inefficiencies by using a more efficient mixing technique inside the outlet fitting itself, post column reaction loops can be removed with resulting improvement in signal to noise response, plus the separation efficiency is maintained. We assessed two methods of HPLC-PCD antioxidant analysis based on the ferric reducing antioxidant power (FRAP) assay in both conventional and reaction flow HPLC-PCD modes. It was found that the reaction flow technique demonstrated significant advantages over the conventional technique in terms of signal to noise, linear range, precision and observed separation efficiency.

18.
N Engl J Med ; 374(10): 940-50, 2016 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-26962729

RESUMO

BACKGROUND: A report from a high-volume single center indicated a survival benefit of receiving a kidney transplant from an HLA-incompatible live donor as compared with remaining on the waiting list, whether or not a kidney from a deceased donor was received. The generalizability of that finding is unclear. METHODS: In a 22-center study, we estimated the survival benefit for 1025 recipients of kidney transplants from HLA-incompatible live donors who were matched with controls who remained on the waiting list or received a transplant from a deceased donor (waiting-list-or-transplant control group) and controls who remained on the waiting list but did not receive a transplant (waiting-list-only control group). We analyzed the data with and without patients from the highest-volume center in the study. RESULTS: Recipients of kidney transplants from incompatible live donors had a higher survival rate than either control group at 1 year (95.0%, vs. 94.0% for the waiting-list-or-transplant control group and 89.6% for the waiting-list-only control group), 3 years (91.7% vs. 83.6% and 72.7%, respectively), 5 years (86.0% vs. 74.4% and 59.2%), and 8 years (76.5% vs. 62.9% and 43.9%) (P<0.001 for all comparisons with the two control groups). The survival benefit was significant at 8 years across all levels of donor-specific antibody: 89.2% for recipients of kidney transplants from incompatible live donors who had a positive Luminex assay for anti-HLA antibody but a negative flow-cytometric cross-match versus 65.0% for the waiting-list-or-transplant control group and 47.1% for the waiting-list-only control group; 76.3% for recipients with a positive flow-cytometric cross-match but a negative cytotoxic cross-match versus 63.3% and 43.0% in the two control groups, respectively; and 71.0% for recipients with a positive cytotoxic cross-match versus 61.5% and 43.7%, respectively. The findings did not change when patients from the highest-volume center were excluded. CONCLUSIONS: This multicenter study validated single-center evidence that patients who received kidney transplants from HLA-incompatible live donors had a substantial survival benefit as compared with patients who did not undergo transplantation and those who waited for transplants from deceased donors. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases.).


Assuntos
Histocompatibilidade , Transplante de Rim , Doadores Vivos , Sobrevivência de Enxerto , Antígenos HLA , Teste de Histocompatibilidade , Humanos , Transplante de Rim/mortalidade , Análise de Sobrevida , Obtenção de Tecidos e Órgãos , Listas de Espera
19.
Technology (Singap World Sci) ; 3(4): 201-213, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26909365

RESUMO

Complete blood cell counts (CBCs) are one of the most commonly ordered and informative blood tests in hospitals. The results from a CBC, which typically include white blood cell (WBC) counts with differentials, red blood cell (RBC) counts, platelet counts and hemoglobin measurements, can have implications for the diagnosis and screening of hundreds of diseases and treatments. Bulky and expensive hematology analyzers are currently used as a gold standard for acquiring CBCs. For nearly all CBCs performed today, the patient must travel to either a hospital with a large laboratory or to a centralized lab testing facility. There is a tremendous need for an automated, portable point-of-care blood cell counter that could yield results in a matter of minutes from a drop of blood without any trained professionals to operate the instrument. We have developed microfluidic biochips capable of a partial CBC using only a drop of whole blood. Total leukocyte and their 3-part differential count are obtained from 10 µL of blood after on-chip lysing of the RBCs and counting of the leukocytes electrically using microfabricated platinum electrodes. For RBCs and platelets, 1 µL of whole blood is diluted with PBS on-chip and the cells are counted electrically. The total time for measurement is under 20 minutes. We demonstrate a high correlation of blood cell counts compared to results acquired with a commercial hematology analyzer. This technology could potentially have tremendous applications in hospitals at the bedside, private clinics, retail clinics and the developing world.

20.
Lab Chip ; 14(22): 4370-81, 2014 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-25231594

RESUMO

Particle counting finds many industrial applications especially in medical healthcare. In particular, cell counting from whole blood is used pervasively for disease diagnostics. Microfluidic impedance cytometry is fast, requires a small volume of blood, can be used at point of care and can perform absolute enumeration of different cell types in the sample. Coincidence detection is very essential for accurate counting results and becomes more significant while counting specific target cells, e.g. CD4(+) or CD8(+) T cell count in HIV/AIDS patient blood samples. In heterogeneous samples, e.g. blood, cell differentiation for all coincidence occurrences is essential in addition to the coincidence detection for accurate cell enumeration. In this paper, we have characterized the coincidence detection with cell differentiation using a microfluidic impedance biochip. The pure population of leukocytes is obtained after all erythrocytes are lysed on-chip from whole blood. Leukocytes were counted electrically as they pass over coplanar microfabricated electrodes bonded to the 15 µm × 15 µm cross section counting channel while generating a bipolar pulse for each cell passage. We have developed a mathematical model to simulate the electrical cell pulse and its coincidences. We show that coincidence detection can be characterized into three main types based on the range of time delay at which the coincidence occurs. We have also characterized cell differentiation for all the three coincidence types and show that multiple coincidences of different types can also occur. We used healthy and HIV-infected patient blood samples and used our coincidence detection technique to count CD4(+) and CD8(+) T cells and show the improvement in accuracy of cell counts compared to that without coincidence detection. We have also shown the improvement in the erythrocyte counting with coincidence detection in diluted whole blood samples.


Assuntos
Contagem de Células Sanguíneas , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD8-Positivos/citologia , Eritrócitos/citologia , Técnicas Analíticas Microfluídicas/instrumentação , Impedância Elétrica , Eletrodos , Desenho de Equipamento , Contagem de Eritrócitos , HIV/isolamento & purificação , Infecções por HIV/sangue , Humanos , Dispositivos Lab-On-A-Chip , Contagem de Linfócitos
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