A primary limitation to real-time imaging of metabolites and proteins has been the selective detection of biomolecules that have no naturally occurring or stable molecular recognition counterparts. ...We present developments in the design of synthetic near-infrared fluorescent nanosensors based on the fluorescence modulation of single-walled carbon nanotubes (SWNTs) with select sequences of surface-adsorbed N-substituted glycine peptoid polymers. We assess the stability of the peptoid-SWNT nanosensor candidates under variable ionic strengths, protease exposure, and cell culture media conditions and find that the stability of peptoid-SWNTs depends on the composition and length of the peptoid polymer. From our library, we identify a peptoid-SWNT assembly that can detect lectin protein wheat germ agglutinin (WGA) with a sensitivity comparable to the concentration of serum proteins. To demonstrate the retention of nanosensor-bound protein activity, we show that WGA on the nanosensor produces an additional fluorescent signal modulation upon exposure to the lectin’s target sugars, suggesting the lectin protein remains active and selectively binds its target sugars through ternary molecular recognition interactions relayed to the nanosensor. Our results inform design considerations for developing synthetic molecular recognition elements by assembling peptoid polymers on SWNTs and also demonstrate these assemblies can serve as optical nanosensors for lectin proteins and their target sugars. Together, these data suggest certain peptoid sequences can be assembled with SWNTs to serve as versatile optical probes to detect proteins and their molecular substrates.
At least 5% of individuals with hypertension have adrenal aldosterone-producing adenomas (APAs). Gain-of-function mutations in KCNJ5 and apparent loss-of-function mutations in ATP1A1 and ATP2A3 were ...reported to occur in APAs. We find that KCNJ5 mutations are common in APAs resembling cortisol-secreting cells of the adrenal zona fasciculata but are absent in a subset of APAs resembling the aldosterone-secreting cells of the adrenal zona glomerulosa. We performed exome sequencing of ten zona glomerulosa-like APAs and identified nine with somatic mutations in either ATP1A1, encoding the Na(+)/K(+) ATPase α1 subunit, or CACNA1D, encoding Cav1.3. The ATP1A1 mutations all caused inward leak currents under physiological conditions, and the CACNA1D mutations induced a shift of voltage-dependent gating to more negative voltages, suppressed inactivation or increased currents. Many APAs with these mutations were <1 cm in diameter and had been overlooked on conventional adrenal imaging. Recognition of the distinct genotype and phenotype for this subset of APAs could facilitate diagnosis.
Until about 1900, large proportions of the world population endured hunger and poverty. The 20th century saw world population increase from 1.6 to 6.1 billion, accompanied and to some extent made ...possible by rapid improvements in health standards and food supply, with associated advances in agricultural and nutrition sciences. In this paper, I use the application of linear programming (LP) in preparation of rations for farm animals to illustrate a method of calculating the lowest cost of a human diet selected from locally available food items, constrained to provide recommended levels of food energy and nutrients; then, to find a realistic minimum cost, I apply the further constraint that the main sources of food energy in the costed diet are weighted in proportion to the actual reported consumption of food items in that area. Worldwide variations in dietary preferences raise the issue as to the sustainability of popular dietary regimes, and the paper reviews the factors associated with satisfying requirements for adequate nutrition within those regimes. The ultimate physical constraints on food supply are described, together with the ways in which climate change may affect those constraints. During the 20th century, food supply increased sufficiently in most areas to keep pace with the rapid increase in world population. Many challenges will need to be overcome if food supply is to continue to meet demand, and those challenges are made more severe by rising expectations of quality of life in the developing world, as well as by the impacts of climate change on agriculture and aquaculture.
Diagnosis of autoimmune hepatitis (AIH) may be challenging. However, early diagnosis is important because immunosuppression is life‐saving. Diagnostic criteria of the International Autoimmune ...Hepatitis Group (IAIHG) were complex and purely meant for scientific purposes. This study of the IAIHG aims to define simplified diagnostic criteria for routine clinical practice. Candidate criteria included sex, age, autoantibodies, immunoglobulins, absence of viral hepatitis, and histology. The training set included 250 AIH patients and 193 controls from 11 centers worldwide. Scores were built from variables showing predictive ability in univariate analysis. Diagnostic value of each score was assessed by the area under the receiver operating characteristic (ROC) curve. The best score was validated using data of an additional 109 AIH patients and 284 controls. This score included autoantibodies, immunoglobulin G, histology, and exclusion of viral hepatitis. The area under the curve for prediction of AIH was 0.946 in the training set and 0.91 in the validation set. Based on the ROC curves, two cutoff points were chosen. The score was found to have 88% sensitivity and 97% specificity (cutoff ≥6) and 81% sensitivity and 99% specificity (cutoff ≥7) in the validation set. Conclusion: A reliable diagnosis of AIH can be made using a very simple diagnostic score. We propose the diagnosis of probable AIH at a cutoff point greater than 6 points and definite AIH 7 points or higher. (HEPATOLOGY 2008.)
A key limitation for achieving deep imaging in biological structures lies in photon absorption and scattering leading to attenuation of fluorescence. In particular, neurotransmitter imaging is ...challenging in the biologically relevant context of the intact brain for which photons must traverse the cranium, skin, and bone. Thus, fluorescence imaging is limited to the surface cortical layers of the brain, only achievable with craniotomy. Herein, this study describes optimal excitation and emission wavelengths for through‐cranium imaging, and demonstrates that near‐infrared emissive nanosensors can be photoexcited using a two‐photon 1560 nm excitation source. Dopamine‐sensitive nanosensors can undergo two‐photon excitation, and provide chirality‐dependent responses selective for dopamine with fluorescent turn‐on responses varying between 20% and 350%. The two‐photon absorption cross‐section and quantum yield of dopamine nanosensors are further calculated, and a two‐photon power law relationship for the nanosensor excitation process is confirmed. Finally, the improved image quality of the nanosensors embedded 2‐mm‐deep into a brain‐mimetic tissue phantom is shown, whereby one‐photon excitation yields 42% scattering, in contrast to 4% scattering when the same object is imaged under two‐photon excitation. The approach overcomes traditional limitations in deep‐tissue fluorescence microscopy, and can enable neurotransmitter imaging in the biologically relevant milieu of the intact and living brain.
The two‐photon excitation of single‐walled carbon nanotube nanosensors produces a near‐infrared fluorescent signal in response to the neurotransmitter dopamine. Both the excitation (1560 nm) and emission (900–1400 nm) wavelengths fall within a local transmittance maximum for brain tissue, scalp, and cranial bone, enabling dopamine imaging deep into highly scattering media.
The final synthetic step in the synthesis of cediranib, AZD2171, 1, is the alkylation of a phenol with an alkyl halide to generate an ether. Our need to understand and control the formation of ...synthetic impurities generated in this step of the synthesis led us to investigate the kinetics and mechanism of the alkylation of indolphenol, 2, 4-(4-fluoro-2-methyl-1H-indol-5-yl)oxy-6-methoxyquinazolin-7-ol, by chloropyrrolidine, 3, 1-(3-chloropropyl)pyrrolidine. Studies in 1-methyl-2-pyrrolidinone (NMP) established that the active alkylating agent is the azetidinium ion, 4, 4-azoniaspiro3.4octane, formed via a slow intramolecular cyclization reaction of chloropyrrolidine, 3. The azetidinium ion was isolated as its tetraphenylborate salt from water by heating 3 in the presence of aqueous potassium tetraphenyl borate, and its competence as an intermediate was demonstrated by its fast reaction with 2 to yield cediranib, 1.
A few reports have suggested that AIH may be less severe in the elderly and may be underdiagnosed, but there is a paucity of data.
We have undertaken a systematic analysis of 164 consecutive patients ...(36 males, 128 females) with definite AIH (median score 23, range 18–28) attending our clinics, comparing those presenting at age >60 years (Group 1,
n
=
43) with those presenting at <60 years (Group 2,
n
=
121).
Median (range) duration of follow-up was 9 years (1–28) in Group 1 and 14 years (1–33) in Group 2. Median ages (ranges) at presentation were: Group 1
=
65 (60–79) and Group 2
=
41 (6–59). Group 1 patients had a significantly increased incidence of ascites at presentation (
p
<
0.001) and a lower incidence of relapse (42% vs. 70%,
p
=
0.002), but there were no significant differences between the groups with respect to mode of onset (acute, insidious, asymptomatic), other clinical signs at presentation, biochemical parameters, types or titres of autoantibodies, incidence of histological cirrhosis, response to therapy or related side effects. There were also no significant differences in liver-related deaths or transplantation, or the frequencies of HLA DR3 or DR4 – although there was an increased frequency of the A1-B8-DR3/4 haplotype in Group 2 (40% vs. 22%,
p
=
0.138).
These findings suggest that AIH often presents in older patients, who frequently have severe disease. Active management in these patients can lead to a normal life expectancy.
Background/Aims Autoimmune hepatitis (AIH) predominantly affects women. Reasons for this are unclear and few series have assessed long-term outcomes of men with AIH. Methods To evaluate the clinical ...course and outcomes of 51 men from a total of 238 consecutive patients with definite AIH at a single centre from 1971 to 2005. The primary outcome measure was death or liver transplantation. Results Median age at diagnosis was 39 y in men and 49 y in women ( p = 0.0589). HLA A1, B8 and DR3 allotypes and the HLA A1–B8–DR3 haplotype were more frequently expressed in men (63% vs. 45%, p = 0.049; 74% vs. 38%, p < 0.001; 62% vs. 44%, p = 0.058; and 50% vs. 23%, p = 0.003; respectively). There were no significant differences in clinical manifestations at presentation. Over 96% of patients demonstrated a complete initial response to treatment. A greater number of men experienced at least one relapse (71% vs. 55%, p = 0.0591). However, women were significantly more likely to die or require liver transplantation (Log rank test p = 0.024). Conclusions Men with AIH appear to have a higher relapse rate and younger age of disease onset which may relate to increased prevalence of HLA A1–B8–DR3. Despite this, men have significantly better long-term survival and outcomes than women.
Imaging the dynamic behavior of neuromodulatory neurotransmitters in the extracelluar space that arise from individual quantal release events would constitute a major advance in neurochemical ...imaging. Spatial and temporal resolution of these highly stochastic neuromodulatory events requires concurrent advances in the chemical development of optical nanosensors selective for neuromodulators in concert with advances in imaging methodologies to capture millisecond neurotransmitter release. Herein, we develop and implement a stochastic model to describe dopamine dynamics in the extracellular space (ECS) of the brain dorsal striatum to guide the design and implementation of fluorescent neurochemical probes that record neurotransmitter dynamics in the ECS. Our model is developed from first-principles and simulates release, diffusion, and reuptake of dopamine in a 3D simulation volume of striatal tissue. We find that in vivo imaging of neuromodulation requires simultaneous optimization of dopamine nanosensor reversibility and sensitivity: dopamine imaging in the striatum or nucleus accumbens requires nanosensors with an optimal dopamine dissociation constant (K d) of 1 μM, whereas K ds above 10 μM are required for dopamine imaging in the prefrontal cortex. Furthermore, as a result of the probabilistic nature of dopamine terminal activity in the striatum, our model reveals that imaging frame rates of 20 Hz are optimal for recording temporally resolved dopamine release events. Our work provides a modeling platform to probe how complex neuromodulatory processes can be studied with fluorescent nanosensors and enables direct evaluation of nanosensor chemistry and imaging hardware parameters. Our stochastic model is generic for evaluating fluorescent neurotransmission probes, and is broadly applicable to the design of other neurotransmitter fluorophores and their optimization for implementation in vivo.
Bacteria classified in species of the genus Leptothrix produce extracellular, microtubular, Fe-encrusted sheaths. The encrustation has been previously linked to bacterial Fe oxidases, which oxidize ...Fe(II) to Fe(III) and/or active groups of bacterial exopolymers within sheaths to attract and bind aqueous-phase inorganics. When L. cholodnii SP-6 cells were cultured in media amended with high Fe(II) concentrations, Fe(III) precipitates visibly formed immediately after addition of Fe(II) to the medium, suggesting prompt abiotic oxidation of Fe(II) to Fe(III). Intriguingly, these precipitates were deposited onto the sheath surface of bacterial cells as the population was actively growing. When Fe(III) was added to the medium, similar precipitates formed in the medium first and were abiotically deposited onto the sheath surfaces. The precipitates in the Fe(II) medium were composed of assemblies of globular, amorphous particles (ca. 50 nm diameter), while those in the Fe(III) medium were composed of large, aggregated particles (≥3 µm diameter) with a similar amorphous structure. These precipitates also adhered to cell-free sheaths. We thus concluded that direct abiotic deposition of Fe complexes onto the sheath surface occurs independently of cellular activity in liquid media containing Fe salts, although it remains unclear how this deposition is associated with the previously proposed mechanisms (oxidation enzyme- and/or active group of organic components-involved) of Fe encrustation of the Leptothrix sheaths.
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