Parallel microfluidic synthesis of size-tunable polymeric nanoparticles using 3D flow focusing towards in vivo study

Microfluidic synthesis of nanoparticles (NPs) can enhance the controllability and reproducibility in physicochemical properties of NPs compared to bulk synthesis methods. However, applications of microfluidic synthesis are typically limited to in vitro studies due to low production rates. Herein, we report the parallelization of NP synthesis by 3D hydrodynamic flow focusing (HFF) using a multilayer microfluidic system to enhance the production rate without losing the advantages of reproducibility, controllability, and robustness. Using parallel 3D HFF, polymeric poly(lactide-co-glycolide)-b-polyethyleneglycol (PLGA-PEG) NPs with sizes tunable in the range of 13-150 nm could be synthesized reproducibly with high production rate. As a proof of concept, we used this system to perform in vivo pharmacokinetic and biodistribution study of small (20 nm diameter) PLGA-PEG NPs that are otherwise difficult to synthesize. Microfluidic parallelization thus enables synthesis of NPs with tunable properties with production rates suitable for both in vitro and in vivo studies

Is chronic kidney disease associated with diabetic retinopathy in Asian adults?

Background: Diabetic nephropathy (DN) is commonly associated with diabetic retinopathy (DR). Few studies have demonstrated that chronic kidney disease (CKD) is associated with DR. However, it is not clear if CKD in the absence of albuminuria is associated with DR. Methods: We included 301 participants with diabetes (Chinese, Malay and Indian ethnicity aged ≥24 years who participated in the Singapore Prospective Study Program (2003-2007). Retinal photographs taken from both eyes were graded for DR using the modified Airlie House Classification. We examined the association of CKD defined by low estimated glomerular filtration rate (eGFR) (&lt;60mL/min per 1.73m2, n=54), and albuminuria (urinary albumin-to-creatinine ratio ≥30, n = 116) with any-DR (n=99) in logistic regression models. We replicated this analysis in another independent population-based sample of Malay adults (n=265) with similar methodology in Singapore. Results: 41% of those with low-eGFR had normoalbuminuria. In separate models, while albuminuria was significantly associated with any-DR, low-eGFR was not significantly associated with any-DR. In a model combining both markers, compared to the referent group (normal-eGFR+normoalbuminuria), the odds ratio (OR) (95% confidence interval [CI]) of any-DR were: 2.33 (1.27-4.27) for normal-eGFR+albuminuria, 1.38 (0.49-3.91) for low-eGFR + normoalbuminuria, and 2.64 (1.05-6.63) for low-eGFR+albuminuria. Similar findings for any-DR were observed in the replication cohort of Malay persons (3.56 [1.49-8.54] for normal-eGFR+albuminuria, 1.69 (0.52-5.55) for low-eGFR+normoalbuminuria, 4.34 [1.68-11.24] for low-eGFR+albuminuria.Conclusion: We demonstrated that CKD is associated with DR only in the presence of albuminuria suggesting that CKD is more likely related to diabetes in the presence of albuminuria.</p

Proton Pump Inhibitors: Are We Still Prescribing Them Without Valid Indications?

BackgroundEvidence from several Western studies has shown an alarmingly high and inappropriate rate of prescription of proton pump inhibitors (PPIs), which may be associated with increased healthcare costs and adverse outcomes. PPI prescribing patterns remain largely unknown in well- developed healthcare systems in Southeast Asia.AimsWe aimed to determine the prevalence of inappropriate prescription of PPI among elderly patients without documentation of valid indications, in a tertiary teaching hospital in Singapore.MethodsWe carried out a retrospective clinical records review of 150 elderly patients aged ≥65 years that had been admitted to two internal medicine wards between 25 May 2011 and 28 June 2011 to determine the appropriateness of indications for PPIs prescribed at hospital discharge. PPI indications were categorised as “valid”, “likely invalid”, and “probable” based on current clinical literature. Pre-admission and discharge prescriptions were reviewed to determine continuation of pre-admission and new PPI prescriptions at discharge. Data on clinical characteristics and concurrent use of ulcerogenic medications were collected.ResultsFrom a total of 150 patients, 80 (53 per cent) received prescriptions for PPIs. Of these, 65 (81.2 per cent) had no valid documented indications (i.e., the indication was classed as “likely invalid”); 10 (12.5 per cent) had valid indications; and in five cases (6.2 per cent) the indication was “probable”. The most common “likely invalid” indication was primary gastrointestinal bleeding prophylaxis (GIP) among low-dose aspirin users in 28 patients (43 per cent) of invalid PPI prescriptions.ConclusionInappropriate prescribing of PPIs without documented valid indications was prevalent among elderly patients at our tertiary teaching hospital in Singapore, providing evidence that shows a similar trend to PPI prescribing to data from Western countries

Increased levels of (class switched) memory B cells in peripheral blood of current smokers

There is increasing evidence that a specific immune response contributes to the pathogenesis of COPD. B-cell follicles are present in lung tissue and increased anti-elastin titers have been found in plasma of COPD patients. Additionally, regulatory T cells (Tregs) have been implicated in its pathogenesis as they control immunological reactions. We hypothesize that the specific immune response in COPD is smoke induced, either by a direct effect of smoking or as a result of smoke-induced lung tissue destruction (i.e. formation of neo-epitopes or auto antigens). Furthermore, we propose that Tregs are involved in the suppression of this smoke-induced specific immune response

Synthesis of size-tunable polymeric nanoparticles enabled by 3D hydrodynamic flow focusing in single-layer microchannels

Author Manuscript date: 2011 June 27A versatile microfluidic platform to synthesize NPs by nanoprecipitation using 3D hydrodynamic flow focusing isolates the precipitating precursors from channel walls, eliminating fouling of the channels. It is shown that this new method enables robust nanoprecipitation without polymer aggregation, regardless of the polymer molecular weight or precursor concentration implemented, where the size of the resulting polymeric NPs is tunable.David H. Koch (Prostate Cancer Foundation Award in Nanotherapeutics)National Institutes of Health (U.S.) (Grant CA119349)National Science Foundation (U.S.) (Graduate Research Fellowship

MicroRNAs in cardiac arrhythmia: DNA sequence variation of MiR-1 and MiR-133A in long QT syndrome.

Long QT syndrome (LQTS) is a genetic cardiac condition associated with prolonged ventricular repolarization, primarily a result of perturbations in cardiac ion channels, which predisposes individuals to life-threatening arrhythmias. Using DNA screening and sequencing methods, over 700 different LQTS-causing mutations have been identified in 13 genes worldwide. Despite this, the genetic cause of 30-50% of LQTS is presently unknown. MicroRNAs (miRNAs) are small (∼ 22 nucleotides) noncoding RNAs which post-transcriptionally regulate gene expression by binding complementary sequences within messenger RNAs (mRNAs). The human genome encodes over 1800 miRNAs, which target about 60% of human genes. Consequently, miRNAs are likely to regulate many complex processes in the body, indeed aberrant expression of various miRNA species has been implicated in numerous disease states, including cardiovascular diseases. MiR-1 and MiR-133A are the most abundant miRNAs in the heart and have both been reported to regulate cardiac ion channels. We hypothesized that, as a consequence of their role in regulating cardiac ion channels, genetic variation in the genes which encode MiR-1 and MiR-133A might explain some cases of LQTS. Four miRNA genes (miR-1-1, miR-1-2, miR-133a-1 and miR-133a-2), which encode MiR-1 and MiR-133A, were sequenced in 125 LQTS probands. No genetic variants were identified in miR-1-1 or miR-133a-1; but in miR-1-2 we identified a single substitution (n.100A> G) and in miR-133a-2 we identified two substitutions (n.-19G> A and n.98C> T). None of the variants affect the mature miRNA products. Our findings indicate that sequence variants of miR-1-1, miR-1-2, miR-133a-1 and miR-133a-2 are not a cause of LQTS in this cohort

Early lipofuscin accumulation in Frontal Lobe Epilepsy

OBJECTIVE: This study reports on a novel brain pathology in young patients with frontal lobe epilepsy (FLE) that is distinct from focal cortical dysplasia (FCD). METHODS: Surgical specimens from 20 young adults with FLE (mean age, 30 years) were investigated with histological/immunohistochemical markers for cortical laminar architecture, mammalian target of (mTOR) pathway activation and inhibition, cellular autophagy, and synaptic vesicle-mediated trafficking as well as proteomics analysis. Findings were correlated with pre-/postoperative clinical, imaging, and electrophysiological data. RESULTS: Excessive lipofuscin accumulation was observed in abnormal dysmorphic neurones in 6 cases, but not in seven FCD type IIB and 7 pathology-negative cases, despite similar age and seizure histories. Abnormal dysmorphic neurones on proteomics analysis were comparable to aged human brains. The mTOR pathway was activated, as in cases with dysplasia, but the immunoreactivities of nucleoporin p62, DEP-domain containing protein 5, clathrin, and dynamin-1 were different between groups, suggesting that enhanced autophagy flux and abnormal synaptic vesicle trafficking contribute to early lipofuscin aggregation in these cases, compared to suppression of autophagy in cases with typical dysplasia. Cases with abnormal neuronal lipofuscin showed subtle magnetic resonance imaging cortical abnormalities that localized with seizure onset zone and were more likely to have a family history. INTERPRETATION: We propose that excess neuronal lipofuscin accumulation in young patients with FLE represents a novel pathology underlying this epilepsy; the early accumulation of lipofuscin may be disease driven, secondary to as-yet unidentified drivers accelerating autophagic pathways, which may underpin the neuronal dysfunction in this condition

An automated method to detect and quantify fungiform papillae in the human tongue: validation and relationship to phenotypical differences in taste perception

Determination of the number of fungiform papillae (FP) on the human tongue is an important measure that has frequently been associated with individual differences in oral perception, including taste sensitivity. At present, there is no standardised method consistently used to identify the number of FP, and primarily scientists manually count papillae over a small region(s) of the anterior tip of a stained tongue. In this study, a rapid automated method was developed to quantify the number of FP across the anterior 2 cm of an unstained tongue from high resolution digital images. In 60 participants, the automated method was validated against traditional manual counting, and then used to assess the relationship between the number of FP and taste phenotype (both 6-n-propylthiouracil (PROP) and Thermal Taster Status). FP count on the anterior 2 cm of the tongue was found to correlate significantly with PROP taster status. PROP supertasters (PSTs) had a significantly higher FP count compared with PROP non-tasters (PNTs). Conversely, the common approach used to determine the number of FP in a small 6 mm diameter circle on the anterior tongue tip, did not show a significant correlation irrespective of whether it was determined via automated or manual counting. The regional distribution of FP was assessed across PROP taster status groups. PSTs had a significantly higher FP count within the first centimetre of the anterior tongue compared with the PNT and PROP medium-tasters (PMT), with no significant difference in the second centimetre. No significant relationship was found with Thermal Taster Status and FP count, or interaction with PROP taster status groups, supporting previous evidence suggesting these phenomena are independent. The automated method is a valuable tool, enabling reliable quantification of FP over the anterior 2 cm surface of the tongue, and overcomes subjective discrepancies in manual counting

miR-22 Forms a Regulatory Loop in PTEN/AKT Pathway and Modulates Signaling Kinetics

Background: The tumor suppressor PTEN (phosphatase and tensin homolog) is a lipid phosphatase that converts PIP3 into PIP2 and downregulates the kinase AKT and its proliferative and anti-apoptotic activities. The FoxO transcription factors are PTEN downstream effectors whose activity is negatively regulated by AKT-mediated phosphorylation. PTEN activity is frequently lost in many types of cancer, leading to increased cell survival and cell cycle progression. Principal Findings: Here we characterize the widely expressed miR-22 and report that miR-22 is a novel regulatory molecule in the PTEN/AKT pathway. miR-22 downregulates PTEN levels acting directly through a specific site on PTEN 39UTR. Interestingly, miR-22 itself is upregulated by AKT, suggesting that miR-22 forms a feed-forward circuit in this pathway. Timeresolved live imaging of AKT-dependent FoxO1 phosphorylation revealed that miR-22 accelerated AKT activity upon growth factor stimulation, and attenuated its down regulation by serum withdrawal. Conclusions: Our results suggest that miR-22 acts to fine-tune the dynamics of PTEN/AKT/FoxO1 pathway