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1.
Heliyon ; 10(8): e29788, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38699741

RESUMO

The research provides a comprehensive analysis of Mystus gulio including growth pattern, growth parameters, recruitment patterns, mortality rates, biomass, exploitation rate (E), and the estimation of maximum sustainable yield (MSY) within the southwestern coastal waters of Bangladesh. From January to December 2017, fishers provided around 1200 specimens. FAO-ICLARM Stock Assessment Tool and Excel-add-in-solver were used to assess stock status through length-frequency data. Indeed, the research findings indicated that the population of M. gulio displayed negative allometric for both individuals (b = 2.53 for male, b = 2.50 for female), as demonstrated by the calculated allometric coefficient value. Nonetheless, the population's dynamic characteristics revealed an asymptotic length (L∞) of 19.34 cm, 23.28 cm and growth coefficient (K) 0.94 year-1 and 0.81 year-1 for male and female M. gulio. The growth performance indexes (Ø') of 2.55 and 2.64 for male and female and maximum lifespan (tmax) 3.20 years and 3.70 years respectively. This study revealed that the slightly variations in the natural mortality rate (M) for both specimens at 1.55 year-1 and 1.59 year-1. The fishing mortality rate (F) 2.75 year-1 and 1.98 year-1and total mortality rate (Z) 4.30 year-1 and 3.57 year-1 for male and females, respectively. The maximum permissible exploitation rate (Emax = 0.421) was lower than the actual exploitation rate (E = 0.63). The MSY was calculated at 67.968 metric tons. Without a doubt, overfishing stands out as the most critical threat to the wild stock. Therefore, it is clear that the existing fishing approach was not efficiently managed the standing stock in a sustainable manner. The findings would be useful for established proper fishing regulations in coastal waters and the surrounding ecosystems.

2.
Neurobiol Aging ; 140: 12-21, 2024 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-38701647

RESUMO

The aging population suffers from memory impairments. Slow-wave activity (SWA) is composed of slow (0.5-1 Hz) and delta (1-4 Hz) oscillations, which play important roles in long-term memory and working memory function respectively. SWA disruptions might lead to memory disturbances often experienced by older adults. We conducted behavioral tests in young and older C57BL/6 J mice. SWA was monitored using wide-field imaging with voltage sensors. Cell-specific calcium imaging was used to monitor the activity of excitatory and inhibitory neurons in these mice. Older mice exhibited impairments in working memory but not memory consolidation. Voltage-sensor imaging revealed aberrant synchronization of neuronal activity in older mice. Notably, we found older mice exhibited no significant alterations in slow oscillations, whereas there was a significant increase in delta power compared to young mice. Calcium imaging revealed hypoactivity in inhibitory neurons of older mice. Combined, these results suggest that neural activity disruptions might correlate with aberrant memory performance in older mice.

3.
Heliyon ; 9(12): e22777, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38094053

RESUMO

Badis badis (Hamilton, 1822) is a popular ornamental fish species in the world. This study provides valuable insights into some biological indices of B. badis using a sample of 293 individuals. These individuals were captured from June 2021 to May 2022 using several traditional fish harvesting gears and traps in the Babu Mondoler beel, a wetland ecosystem in NW Bangladesh. Biometric data were collected for each individual, contributing to a comprehensive understanding of this species. The recorded results revealed a wide range of total length (TL), varying from 2.30 to 11.33 cm. Notably, we observed a maximum length of 11.33 cm TL and a maximum body weight (BW) of 18.18 g, ranging from 0.20 to 18.18 g, setting a new record and showcasing the diversity in size within the population. The estimated allometric coefficient (b) showed that combined sexes had negative allometric growth (b = 2.67). Growth parameters were assessed as L∞ = 11.93 cm, K = 0.95 year-1 and Ø' = 2.13. The tmax was 3.16 years. The Lm was measured at 7.02 cm TL and tm = 0.89 year. In this study, KF (1.4240 ± 0.3194) was best for the wellbeing of B. badis in the study area. The a3.0 was estimated at 0.0079 and the relative weight WR (100.90 ± 16.994). Physiological status showed that maximum fatty fish were observed at 10.00-12.00 cm TL; lowest at 4.0-6.00 cm TL. Moreover, the Z, Mw, F and E were estimated to be 3.29 year-1, 1.45 year-1, 1.84 year-1and 0.56, respectively. Additionally, the Lopt for this species was found to be 7.91 cm TL. The findings from this study hold great potential for enhancing the assessment and management of the specimen in the study area and its ecological community. These valuable insights into the population parameters, growth patterns, and exploitation rates of B. badis can inform future management strategies, ensuring the sustainable utilization of this fishery resource in Bangladesh and others neighboring countries.

4.
Heliyon ; 9(5): e15747, 2023 May.
Artigo em Inglês | MEDLINE | ID: mdl-37206050

RESUMO

Considering the health risks originating from the exposure of metal(loid)s in tap-water and the concomitant vulnerability of school-going students, 25 composite tap water samples from different schools and colleges of central Bangladesh (Mirpur, Dhaka) were analyzed by atomic absorption spectroscopic technique. Elemental abundances of Na, Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Zn, As, Cd, and Pb in the studied tap water samples varied from 4520 to 62250, 2760-29580, 210-3000, 15780-78130, 1.54-5.32, 7.00-196, 2.00-450, 0.04-1.45, 8.23-24.4, 0.10-813, 0.10-10.5, 0.002-0.212, and 1.55-15.8 µgL-1, respectively. Dissolved metal(loid)s' concentrations were mostly within the national and international threshold values with few exceptions which were also consistent with the entropy-based water quality assessment. Multivariate statistical approaches demonstrated that hydro-geochemical processes like water-rock interactions mostly govern the major elemental (Na, Mg, K, Ca) compositions in tap water. However, anthropogenic processes typically control the trace elemental compositions where supply pipeline scaling was identified as the major source. Cluster analysis on sampling sites separated two groups of schools and colleges depending on their establishment years where tap water from older schools and colleges possesses relatively higher levels of metal(loid)s. Hence, gradual pipeline scaling on a temporal scale augmented the metal(loid)s' concentrations in tap-water. In terms of non-carcinogenic health risks estimation, studied tap-water seems to be safe, whereas elemental abundances of Pb and As can cause carcinogenic risks to school-going people. However, progressive deterioration of water quality by pipeline scaling will be supposed to cause significant health risks in the future, for which preventative measures should be adopted.

5.
Front Bioeng Biotechnol ; 11: 1150772, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36970613

RESUMO

Introduction: Glioblastoma (GBM) invasiveness and ability to infiltrate deep into the brain tissue is a major reason for the poor patient prognosis for this type of brain cancer. Behavior of glioblastoma cells, including their motility, and expression of invasion-promoting genes such as matrix metalloprotease-2 (MMP2), are strongly influenced by normal cells found in the brain parenchyma. Cells such as neurons may also be influenced by the tumor, as many glioblastoma patients develop epilepsy. In vitro models of glioblastoma invasiveness are used to supplement animal models in a search for better treatments, and need to combine capability for high-throughput experiments with capturing bidirectional interactions between GBM and brain cells. Methods: In this work, two 3D in vitro models of GBM-cortical interactions were investigated. A matrix-free model was created by co-culturing GBM and cortical spheroids, and a matrix-based model was created by embedding cortical cells and a GBM spheroid in Matrigel. Results: Rapid GBM invasion occurred in the matrix-based model, and was enhanced by the presence of cortical cells. Little invasion occurred in the matrix-free model. In both types of models, presence of GBM cells resulted in a significant increase in paroxysmal neuronal activity. Discussion: Matrix-based model may be better suited for studying GBM invasion in an environment that includes cortical cells, while matrix-free model may be useful in investigation of tumor-associated epilepsy.

6.
Heliyon ; 8(11): e11446, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36387448

RESUMO

For the first time, this study presents the radio-activity concentrations of primordial radionuclides in a suite of classroom-dusts collected from 23 schools in central part of Bangladesh. Bulk elemental compositions from instrumental neutron activation analysis (INAA) were transformed into accompanied radio-activity contents (Bq.kg-1). Mean activity contents of 226Ra, 232Th, & 40K in dust samples were 86.0, 43.4, and 448 Bq.kg-1, respectively, which were comparatively elevated relative to the relevant world average value. Higher NORMs abundances were due to the surface soil weathering and aerodynamic fractionations. Estimation of typical radiological-risk indices demonstrates human health risks. Bearing in mind that the greater susceptibility of school-going juveniles & children to the ionizing-radiations & the entering of NORMs-comprising dust-particle into human lungs, calculated radiological indices merely represent the least potential risk. However, in actual cases, α-particles from the 238U and 232Th-decay series can create significant radiation-damage to the respiratory-system.

7.
Front Psychiatry ; 13: 916160, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36032230

RESUMO

Background: The global effort to develop herd immunity in the general public against the COVID-19 pandemic is currently ongoing. However, to the best of our knowledge, there have been no studies on how the COVID-19 vaccine affects mental health in the context of the COVID-19 pandemic in Bangladesh. The present study investigated the psychological effects and associated factors among vaccinated and unvaccinated general populations against COVID-19 infection in Bangladesh. Methods: A nationwide online cross-sectional survey was conducted in Bangladesh from June 23 to December 25, 2021. The frequency of symptoms of psychological distress, depression, anxiety, stress, post-traumatic stress disorder (PTSD), insomnia, and fear was assessed using the Bangla versions of the GHQ-12, PHQ-2, GAD-2, PSS-4, PC-PTSD-5, ISI, and FCV-19S scales, respectively. Results: The study included 3,013 persons from all eight divisions of Bangladesh, with 1,272 (42.2%) being vaccinated and 1,741 (57.8%) being unvaccinated. Compared with unvaccinated populations, vaccinated populations had significantly lower prevalence rates of psychological distress (36.4 vs. 51.5%), depression (21.1 vs. 37.9%), anxiety (25.1 vs. 44.9%), stress (19.4 vs. 30.4%), PTSD (29.4 vs. 38.3%), insomnia (18.7 vs. 39.4%), and fear symptoms (16.1 vs. 27.5%). Among vaccinated populations, respondents who lived in nuclear families were significantly associated with higher risk of psychological distress (AOR, 1.38; 95% CI, 1.09-1.78), depression (AOR, 1.49; 95% CI, 1.11-1.98), anxiety (AOR, 1.77; 95% CI, 1.21-1.98), and fear (AOR, 1.43; 95% CI, 1.11-1.83) symptoms. Participants who lost family members, friends, or colleagues due to the COVID-19 pandemic had significantly higher risk of symptoms of psychological distress (AOR, 1.35; 95% CI, 1.02-1.79), anxiety (AOR, 1.41; 95% CI, 1.11-1.87), and PTSD (AOR, 1.76; 95% CI, 1.24-2.19). On the other hand, unvaccinated populations who lived in the Dhaka division were significantly associated with an increased risk of depression (AOR, 2.06; 95% CI, 1.40-2.52), anxiety (AOR, 1.86; 95% CI, 1.15-2.47), stress (AOR, 1.92; 95% CI, 1.12-2.88), and insomnia (AOR, 1.88; 95% CI, 1.20-2.94) symptoms. Except for PTSD and fear symptoms, unemployed participants had considerably higher rates of psychological distress, depression, anxiety, stress, and insomnia symptoms (e.g., psychological distress: AOR, 1.83; 95% CI, 1.10-2.62; depression: AOR, 1.74; 95% CI, 1.37-2.19). Conclusions: This study recommends immunizing unvaccinated populations as soon as possible to prevent infection and boost mental health. Vulnerable people needed special care, health-related education, and psychological assistance.

8.
Microsyst Nanoeng ; 7: 67, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34567779

RESUMO

Neuronal cultures are widely used in neuroscience research. However, the randomness of circuits in conventional cultures prevents accurate in vitro modeling of cortical development and of the pathogenesis of neurological and psychiatric disorders. A basic feature of cortical circuits that is not captured in standard cultures of dissociated cortical cells is directional connectivity. In this work, a polydimethylsiloxane (PDMS)-based device that achieves directional connectivity between micro 3D cultures is demonstrated. The device consists of through-holes for micro three-dimensional (µ3D) clusters of cortical cells connected by microtrenches for axon and dendrite guidance. The design of the trenches relies in part on the concept of axonal edge guidance, as well as on the novel concept of specific dendrite targeting. This replicates dominant excitatory connectivity in the cortex, enables the guidance of the axon after it forms a synapse in passing (an "en passant" synapse), and ensures that directional selectivity is preserved over the lifetime of the culture. The directionality of connections was verified morphologically and functionally. Connections were dependent on glutamatergic synapses. The design of this device has the potential to serve as a building block for the reconstruction of more complex cortical circuits in vitro.

9.
J Oleo Sci ; 70(3): 397-407, 2021 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-33583923

RESUMO

The fluoroquinolone antibiotic drug namely ciprofloxacin hydrochloride (CFH) is widely prescribed for the treatment of different bacterial infections. The interaction of CFH with a synthetic polymer, polyvinyl pyrrolidone (PVP), and biopolymer, bovine serum albumin (BSA) was studied by UVvisible and fluorescence spectroscopic methods at different temperatures. The binding constant (K b ) for the CFH-PVP complex was determined from the Benesi-Hildebrand plot. PVP of different molecular weights (MW) (such as 24,000, 40,000, 360,000, and 700,000 g. mole-1) were used for the interaction between CFH and PVP. The gradual increase in K b value and the complexation reaction was found to be much enhanced with the augmentation of the MW of PVP. The values of K b were also found to be increased with increasing temperatures as well as with the increase of electrolyte/acetic acid concentration. The Gibbs free energy of binding (∆G 0) values of the interaction process was negative which indicates the complex formation is thermodynamically spontaneous. The positive values of enthalpy (∆H 0) and entropy (∆S 0) of binding connote that the binding force for CFH-PVP complexation is hydrophobic in nature and the complexation is entropy controlled. The negative intrinsic enthalpy (∆H *,0) values indicate the high stability of CFH-PVP complexes. Molecular docking calculation discloses the existence of similar binding forces between CFH and PVP obtained by the analysis of experimental data from UV-visible spectroscopic method. The binding constant between CFH and BSA (K b ), quenching constant (K sv ), the number of binding sites (n), and the quenching rate constant (K q ) for the CFH-BSA system were also calculated. The values of K sv , K q , and n for the CFH-BSA system are lower in 0.05 mol L-1 urea solution and higher in PVP solutions compared to those of aqueous medium.


Assuntos
Antibacterianos/química , Biopolímeros/química , Ciprofloxacina/química , Simulação de Acoplamento Molecular/métodos , Povidona/análogos & derivados , Soroalbumina Bovina/química , Análise Espectral/métodos , Temperatura , Ácido Acético/química , Interações Medicamentosas , Eletrólitos/química , Peso Molecular , Povidona/química , Soluções , Termodinâmica
10.
Pharmaceuticals (Basel) ; 10(1)2017 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-28230733

RESUMO

Protein kinase CK2 demonstrates increased protein expression relative to non-transformed cells in the majority of cancers that have been examined. The elevated levels of CK2 are involved in promoting not only continued proliferation of cancer cells but also their resistance to cell death; thus, CK2 has emerged as a plausible target for cancer therapy. Our focus has been to target CK2 catalytic subunits at the molecular level using RNA interference (RNAi) strategies to achieve their downregulation. The delivery of oligonucleotide therapeutic agents warrants that they are protected and are delivered specifically to cancer cells. The latter is particularly important since CK2 is a ubiquitous signal that is essential for survival. To achieve these goals, we have developed a nanocapsule that has the properties of delivering an anti-CK2 RNAi therapeutic cargo, in a protected manner, specifically to cancer cells. Tenfibgen (TBG) is used as the ligand to target tenascin-C receptors, which are elevated in cancer cells. This strategy is effective for inhibiting growth and inducing death in several types of xenograft tumors, and the nanocapsule elicits no safety concerns in animals. Further investigation of this therapeutic approach for its translation is warranted.

11.
Oncotarget ; 7(38): 61789-61805, 2016 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-27557516

RESUMO

CK2, a protein serine/threonine kinase, promotes cell proliferation and suppresses cell death. This essential-for-survival signal demonstrates elevated expression and activity in all cancers examined, and is considered an attractive target for cancer therapy. Here, we present data on the efficacy of a tenfibgen (TBG) coated nanocapsule which delivers its cargo of siRNA (siCK2) or single stranded RNA/DNA oligomers (RNAi-CK2) simultaneously targeting CK2α and α' catalytic subunits. Intravenous administration of TBG-siCK2 or TBG-RNAi-CK2 resulted in significant xenograft tumor reduction at low doses in PC3-LN4 and 22Rv1 models of prostate cancer. Malignant cell uptake and specificity in vivo was verified by FACS analysis and immunofluorescent detection of nanocapsules and PCR detection of released oligomers. Dose response was concordant with CK2αα' RNA transcript levels and the tumors demonstrated changes in CK2 protein and in markers of proliferation and cell death. Therapeutic response corresponded to expression levels for argonaute and GW proteins, which function in oligomer processing and translational repression. No toxicity was detected in non-tumor tissues or by serum chemistry. Tumor specific delivery of anti-CK2 RNAi via the TBG nanoencapsulation technology warrants further consideration of translational potential.


Assuntos
Sistemas de Liberação de Medicamentos , Nanocápsulas/química , Fragmentos de Peptídeos/química , Neoplasias da Próstata/tratamento farmacológico , Interferência de RNA , Terapêutica com RNAi , Tenascina/química , Animais , Morte Celular , Linhagem Celular Tumoral , Proliferação de Células , Humanos , Masculino , Camundongos , Camundongos Endogâmicos NOD , Camundongos Nus , Camundongos SCID , Transdução de Sinais , Ensaios Antitumorais Modelo de Xenoenxerto
13.
Biomed Res Int ; 2015: 128256, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26229953

RESUMO

The concentrations of 18 different elements (K, Ca, Fe, Cl, P, Zn, S, Mn, Ti, Cr, Rb, Co, Br, Sr, Ru, Si, Ni, and Cu) were analyzed in five selected vegetables through Proton Induced X-ray Emission (PIXE) technique. The objective of this study was to provide updated information on concentrations of elements in vegetables available in the local markets at Savar subdistrict in Bangladesh. These elements were found in varying concentrations in the studied vegetables. The results also indicated that P, Cl, K, Ca, Mn, Fe, and Zn were found in all vegetables. Overall, K and Ca exhibited the highest concentrations. Cu and Ni exhibited the lowest concentrations in vegetables. The necessity of these elements was also evaluated, based on the established limits of regulatory standards. The findings of this study suggest that the consumption of these vegetables is not completely free of health risks.


Assuntos
Brassica/química , Elementos Químicos , Hyacinthus/química , Lactuca/química , Espectrometria por Raios X/métodos , Spinacia oleracea/química , Verduras/química , Bangladesh
14.
PLoS One ; 9(10): e109970, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25333839

RESUMO

Protected and specific delivery of nucleic acids to malignant cells remains a highly desirable approach for cancer therapy. Here we present data on the physical and chemical characteristics, mechanism of action, and pilot therapeutic efficacy of a tenfibgen (TBG)-shell nanocapsule technology for tumor-directed delivery of single stranded DNA/RNA chimeric oligomers targeting CK2αα' to xenograft tumors in mice. The sub-50 nm size TBG nanocapsule (s50-TBG) is a slightly negatively charged, uniform particle of 15 - 20 nm size which confers protection to the nucleic acid cargo. The DNA/RNA chimeric oligomer (RNAi-CK2) functions to decrease CK2αα' expression levels via both siRNA and antisense mechanisms. Systemic delivery of s50-TBG-RNAi-CK2 specifically targets malignant cells, including tumor cells in bone, and at low doses reduces size and CK2-related signals in orthotopic primary and metastatic xenograft prostate cancer tumors. In conclusion, the s50-TBG nanoencapsulation technology together with the chimeric oligomer targeting CK2αα' offer significant promise for systemic treatment of prostate malignancy.


Assuntos
Caseína Quinase II/genética , Nanocápsulas/administração & dosagem , Fragmentos de Peptídeos/administração & dosagem , Neoplasias da Próstata/tratamento farmacológico , Interferência de RNA , Tenascina/administração & dosagem , Animais , Apoptose/efeitos dos fármacos , Sistemas de Liberação de Medicamentos , Humanos , Masculino , Camundongos , Nanocápsulas/uso terapêutico , Fragmentos de Peptídeos/uso terapêutico , Neoplasias da Próstata/patologia , RNA Interferente Pequeno/genética , Tenascina/uso terapêutico , Transplante Heterólogo
15.
Mol Pharm ; 10(1): 11-7, 2013 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-22656692

RESUMO

Attachment of multiple chelated Gd(3+) ions to the interior of bacteriophage P22 viral capsids affords nanoscale MRI contrast agents with extremely high relaxivity values. Highly fenestrated "wiffleball" morphology is unique to P22 and assures water exchange between the environment and interior cavity of the capsid. The cavity of P22 "wiffleball" was functionalized with a branched oligomer comprising multiple DTPA-Gd complexes resulting in an impressive payload of 1,900 Gd(3+) ions inside each 64 nm capsid. High relaxivities of r(1,ionic) = 21.7 mM(-1) s(-1) and r(1,particle) = 41,300 mM(-1) s(-1) at 298 K, 0.65 T (28 MHz) are reported, with r(1)/r(2) ratio of 0.80 and optimized rotational correlation time for this system. Specific design modifications are suggested for future improvements of viral capsid-based MRI contrast agents directed toward clinical translation.


Assuntos
Bacteriófago P22/química , Capsídeo/química , Meios de Contraste/química , Imageamento por Ressonância Magnética/métodos , Nanocompostos/química , Gadolínio/química , Gadolínio DTPA/química
16.
PLoS One ; 7(11): e48950, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23152827

RESUMO

BACKGROUND: Acute kidney injury (AKI) has grave short- and long-term consequences. Often the onset of AKI is predictable, such as following surgery that compromises blood flow to the kidney. Even in such situations, present therapies cannot prevent AKI. As apoptosis is a major form of cell death following AKI, we determined the efficacy and mechanisms of action of tauroursodeoxycholic acid (TUDCA), a molecule with potent anti-apoptotic and pro-survival properties, in prevention of AKI in rat and cell culture models. TUDCA is particularly attractive from a translational standpoint, as it has a proven safety record in animals and humans. METHODOLOGY/PRINCIPAL FINDINGS: We chose an ischemia-reperfusion model in rats to simulate AKI in native kidneys, and a human kidney cell culture model to simulate AKI associated with cryopreservation in transplanted kidneys. TUDCA significantly ameliorated AKI in the test models due to inhibition of the mitochondrial pathway of apoptosis and upregulation of survival pathways. CONCLUSIONS: This study sets the stage for testing TUDCA in future clinical trials for prevention of AKI, an area that needs urgent attention due to lack of effective therapies.


Assuntos
Injúria Renal Aguda/prevenção & controle , Substâncias Protetoras/farmacologia , Ácido Tauroquenodesoxicólico/farmacologia , Injúria Renal Aguda/patologia , Injúria Renal Aguda/fisiopatologia , Animais , Apoptose/efeitos dos fármacos , Caspases/metabolismo , Técnicas de Cultura de Células , Sobrevivência Celular/efeitos dos fármacos , Modelos Animais de Doenças , Ativação Enzimática/efeitos dos fármacos , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Humanos , Túbulos Renais Proximais/efeitos dos fármacos , Masculino , Substâncias Protetoras/toxicidade , Ratos , Transdução de Sinais/efeitos dos fármacos , Ácido Tauroquenodesoxicólico/toxicidade
17.
Stem Cells ; 30(11): 2596-601, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22948941

RESUMO

The activation of endogenous Oct4 transcription is a key step in the reprogramming of somatic cells into induced pluripotent stem (iPS) cells but until now it has been difficult to analyze this critical event in the reprogramming process. We have generated a transgenic mouse that expresses the tamoxifen-inducible Cre recombinase MerCreMer under the control of the endogenous Oct4 locus, enabling lineage tracing of Oct4 expression in cells in vivo or in vitro, during either reprogramming or differentiation. Using this novel resource, we have determined the timing and outcome of endogenous Oct4 induction during fibroblast reprogramming. We show that both the initiation of this key reprogramming step and the ability of cells activating endogenous Oct4 expression to complete reprogramming are not influenced by the presence of exogenous c-Myc, although the overall efficiency of the process is increased by c-Myc. Oct4 lineage tracing reveals that new reprogramming events continue to initiate over a period of 3 weeks. Furthermore, the analysis of mixed colonies, where only a subset of daughter cells induce endogenous Oct4 expression, indicates the role of unknown, stochastic events in the progression of reprogramming from the initial events to a pluripotent state. Our transgenic mouse model and cells derived from it provide powerful and precise new tools for the study of iPS cell reprogramming mechanisms and have wider implications for the investigation of the role of Oct4 during development.


Assuntos
Células-Tronco Pluripotentes Induzidas/metabolismo , Fator 3 de Transcrição de Octâmero/metabolismo , Animais , Linhagem da Célula , Células Cultivadas , Embrião de Mamíferos/citologia , Fibroblastos/metabolismo , Fibroblastos/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Técnicas de Introdução de Genes , Proteínas de Fluorescência Verde/biossíntese , Proteínas de Fluorescência Verde/genética , Células-Tronco Pluripotentes Induzidas/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Fator 3 de Transcrição de Octâmero/genética , Fenótipo , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/genética , Ativação Transcricional
18.
Chem Commun (Camb) ; 46(2): 264-6, 2010 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-20024346

RESUMO

A branched iron-phenanthroline based coordination polymer has been constructed in a water based system using a click chemistry approach to link monomeric coordination complexes together within a protein cage nanoarchitecture, which acts both as a template and a sized constrained reaction environment.


Assuntos
Proteínas de Choque Térmico Pequenas/química , Polímeros/química , Reagentes de Ligações Cruzadas/química , Portadores de Fármacos/química , Ferro/química , Nanoestruturas/química , Tamanho da Partícula , Fenantrolinas/química , Água/química
19.
Nano Lett ; 9(12): 4520-6, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19888720

RESUMO

A DTPA-Gd containing polymer was grown in the interior of a heat shock protein cage resulting in T(1) particle relaxivities of 4200 mM(-1) sec(-1) for the 12 nm particle. Relaxivity parameters were determined, and this analysis suggests that the rotational correlation time has been optimized while the water exchange lifetime is longer than optimal. This synthetic approach holds much promise for the development of next generation contrast agents and this report will aid in their design.


Assuntos
Meios de Contraste/química , Portadores de Fármacos/química , Gadolínio DTPA/química , Proteínas de Choque Térmico/química , Aumento da Imagem/métodos , Imageamento por Ressonância Magnética/métodos , Complexos Multiproteicos/química , Imagens de Fantasmas
20.
J Am Chem Soc ; 131(12): 4346-54, 2009 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-19317506

RESUMO

A goal of biomimetic chemistry is to use the hierarchical architecture inherent in biological systems to guide the synthesis of functional three-dimensional structures. Viruses and other highly symmetrical protein cage architectures provide defined scaffolds to initiate hierarchical structure assembly. Here we demonstrate that a cross-linked branched polymer can be initiated and synthesized within the interior cavity of a protein cage architecture. Creating this polymer network allows for the spatial control of pendant reactive sites and dramatically increases the stability of the cage architecture. This material was generated by the sequential coupling of multifunctional monomers using click chemistry to create a branched cross-linked polymer network. Analysis of polymer growth by mass spectrometry demonstrated that the polymer was initiated at the interior surface of the cage at genetically introduced cysteine reactive sites. The polymer grew as expected to generation 2.5 where it was limited by the size constraints of the cavity. The polymer network was fully cross-linked across protein subunits that make up the cage and extended the thermal stability for the cage to at least 120 degrees C. The introduced reactive centers were shown to be active and their number density increased with increasing generation. This synthetic approach provides a new avenue for creating defined polymer networks, spatially constrained by a biological template.


Assuntos
Biomimética , Reagentes de Ligações Cruzadas/química , Aminas/química , Cisteína/química , Proteínas de Choque Térmico/química , Lisina/química , Substâncias Macromoleculares , Espectrometria de Massas/métodos , Mathanococcus/metabolismo , Modelos Moleculares , Estrutura Molecular , Polímeros/síntese química , Polímeros/química , Proteínas , Temperatura
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