Molecular mechanisms of developmental pathways in neurological disorders: a pharmacological and therapeutic review

Developmental signalling pathways such as Wnt/β-catenin, Notch and Sonic hedgehog play a central role in nearly all the stages of neuronal development. The term ‘embryonic’ might appear to be a misnomer to several people because these pathways are functional during the early stages of embryonic development and adulthood, albeit to a certain degree. Therefore, any aberration in these pathways or their associated components may contribute towards a detrimental outcome in the form of neurological disorders such as Alzheimer''s disease, Parkinson''s disease, amyotrophic lateral sclerosis and stroke. In the last decade, researchers have extensively studied these pathways to decipher disease-related interactions, which can be used as therapeutic targets to improve outcomes in patients with neurological abnormalities. However, a lot remains to be understood in this domain. Nevertheless, there is strong evidence supporting the fact that embryonic signalling is indeed a crucial mechanism as is manifested by its role in driving memory loss, motor impairments and many other processes after brain trauma. In this review, we explore the key roles of three embryonic pathways in modulating a range of homeostatic processes such as maintaining blood–brain barrier integrity, mitochondrial dynamics and neuroinflammation. In addition, we extensively investigated the effect of these pathways in driving the pathophysiology of a range of disorders such as Alzheimer''s, Parkinson''s and diabetic neuropathy. The concluding section of the review is dedicated to neurotherapeutics, wherein we identify and list a range of biological molecules and compounds that have shown enormous potential in improving prognosis in patients with these disorders.     

RNA-driven JAZF1-SUZ12 gene fusion in human endometrial stromal cells

Oncogenic fusion genes as the result of chromosomal rearrangements are important for understanding genome instability in cancer cells and developing useful cancer therapies. To date, the mechanisms that create such oncogenic fusion genes are poorly understood. Previously we reported an unappreciated RNA-driven mechanism in human prostate cells in which the expression of chimeric RNA induces specified gene fusions in a sequence-dependent manner. One fundamental question yet to be addressed is whether such RNA-driven gene fusion mechanism is generalizable, or rather, a special case restricted to prostate cells. In this report, we demonstrated that the expression of designed chimeric RNAs in human endometrial stromal cells leads to the formation of JAZF1-SUZ12, a cancer fusion gene commonly found in low-grade endometrial stromal sarcomas. The process is specified by the sequence of chimeric RNA involved and inhibited by estrogen or progesterone. Furthermore, it is the antisense rather than sense chimeric RNAs that effectively drive JAZF1-SUZ12 gene fusion. The induced fusion gene is validated both at the RNA and the genomic DNA level. The ability of designed chimeric RNAs to drive and recapitulate the formation of JAZF1-SUZ12 gene fusion in endometrial cells represents another independent case of RNA-driven gene fusion, suggesting that RNA-driven genomic recombination is a permissible mechanism in mammalian cells. The results could have fundamental implications in the role of RNA in genome stability, and provide important insight in early disease mechanisms related to the formation of cancer fusion genes.     

Eriocaulon balakrishnanii (Eriocaulaceae), a new species from the Western Ghats of India

A new species, Eriocaulon balakrishnanii (Eriocaulaceae) from the Western Ghats of Karnataka State in India is described and illustrated. This species is allied to E. robusto-brownianum and E. lanceolatum but differs in a number of characters from both.     

Heterogeneous diacylglycerol acyltransferase expression enhances lipids and PUFA in Chlorella species

Algae have been explored for renewable energy, nutraceuticals, and value-added products. However, low lipid yield is a significant impediment to its commercial viability. Genetic engineering can improve the fatty acid profile of algae without compromising its growth. This study introduced the diacylglycerol acyltransferase (BnDGAT) gene from Brassica napus into Chlorella sorokiniana-I, a fast-growing and thermotolerant natural strain isolated from wastewater, which increased its intracellular lipid accumulation. Hygromycin-resistant cells were selected, and enhanced green florescence protein fluorescence was used to distinguish pure transgenic cell lines from mixed cultures. Compared to the wild type, BnDGAT expression in transgenic C. sorokiniana-I caused a threefold increase in non-polar lipid and a twofold increase in polyunsaturated fatty acids. Nile red staining reaffirmed the presence of higher intracellular lipid bodies in transgenic cells. There was a substantial alteration in the fatty acid profile of transgenic alga expressing BnDGAT. The non-essential omega 9 (C18: 1) fatty acid decreased (5%–7% from 18%), while alpha-linolenic acid, an essential omega 3 fatty acid (C18: 3), was increased (23%–24% from 11%). This study substantiates a valuable strategy for enhancing essential omega-3 fatty acids and neutral lipids to improve its nutritional value for animal feed. The increased lipid productivity should reduce the cost of producing fatty acid methyl esters (FAME). Improved FAME quality should address the clouding issues in cold regions.     

Phylogenetic community patterns suggest Central Indian tropical dry forests are structured by montane climate refuges

Aim

We used an eco-phylogenetic approach to investigate the diversity and assembly patterns of tropical dry forests (TDFs) in Central India. We aimed at informing conservation and restoration practices in these anthropogenically disturbed forests by identifying potential habitats of conservation significance and elements of regional biodiversity most vulnerable to human impact and climate change.

Location

Tropical dry forests of Madhya Pradesh, Central India.

Methods

We analysed the species richness, stem density, basal area and phylogenetic structure (standardized effect size of MNTD, MPD, PD and community evolutionary distinctiveness cED) of 117 tree species assemblages distributed across a ~230 to ~940 m elevational gradient. We examined how these community measures and taxonomic (Sørensen) and phylogenetic (UniFrac) beta diversity varied with elevation, precipitation, temperature and climatic stress.

Results

Species richness, phylogenetic diversity, stem density and basal area were positively correlated with elevation, with high-elevation plots exhibiting cooler temperatures, higher precipitation and lower stress. High-elevation assemblages also trended towards greater phylogenetic dispersion, which diminished at lower elevations and in drier, more stressful plots. Phylogenetic turnover was observed across the elevation gradient, and species evolutionary distinctiveness increased at lower elevations and under harsher abiotic conditions.

Main Conclusions

Harsher abiotic conditions at low elevations may act as a selective filter on plant lineages, leading to phylogenetically clustered low-diversity assemblages. These assemblages contained more evolutionarily distinct species that may contribute disproportionately to biodiversity. Conversely, milder abiotic conditions at high elevations may serve as refuges for drought-sensitive species, resulting in more diverse assemblages. Conservation practices that prioritize both high- and low-elevation habitats could promote the persistence of evolutionarily distinct species and areas of high biodiversity within the Central Indian landscape. Establishing connectivity between these habitats may provide a range of climatic conditions for species to retreat to or persist within as climates change.     

Fetal kidney stem cells ameliorate cisplatin induced acute renal failure and promote renal angiogenesis

AIM: To investigate whether fetal kidney stem cells (fKSC) ameliorate cisplatin induced acute renal failure (ARF) in rats and promote renal angiogenesis.METHODS: The fKSC were isolated from rat fetuses of gestation day 16 and expanded in vitro up to 3^rd passage. They were characterized for the expression of mesenchymal and renal progenitor markers by flow cytometry and immunocytochemistry, respectively. The in vitro differentiation of fKSC towards epithelial lineage was evaluated by the treatment with specific induction medium and their angiogenic potential by matrigel induced tube formation assay. To study the effect of fKSC in ARF, fKSC labeled with PKH26 were infused in rats with cisplatin induced ARF and, the blood and renal tissues of the rats were collected at different time points. Blood biochemical parameters were studied to evaluate renal function. Renal tissues were evaluated for renal architecture, renal cell proliferation and angiogenesis by immunohistochemistry, renal cell apoptosis by terminal deoxynucleotidyl transferase nick-end labeling assay and early expression of angiogenic molecules viz. vascular endothelial growth factor (VEGF), hypoxia-inducible factor (HIF)-1α and endothelial nitric oxide synthase (eNOS) by western blot.RESULTS: The fKSC expressed mesenchymal markers viz. CD29, CD44, CD73, CD90 and CD105 as well as renal progenitor markers viz. Wt1, Pax2 and Six2. They exhibited a potential to form CD31 and Von Willebrand factor expressing capillary-like structures and could be differentiated into cytokeratin (CK)18 and CK19 positive epithelial cells. Administration of fKSC in rats with ARF as compared to administration of saline alone, resulted in a significant improvement in renal function and histology on day 3 (2.33 ± 0.33 vs 3.50 ± 0.34, P < 0.05) and on day 7 (0.83 ± 0.16 vs 2.00 ± 0.25, P < 0.05). The infused PKH26 labeled fKSC were observed to engraft in damaged renal tubules and showed increased proliferation and reduced apoptosis (P < 0.05) of renal cells. The kidneys of fKSC as compared to saline treated rats had a higher capillary density on day 3 [13.30 ± 1.54 vs 7.10 ± 1.29, capillaries/high-power fields (HPF), P < 0.05], and on day 7 (21.10 ± 1.46 vs 15.00 ± 1.30, capillaries/HPF, P < 0.05). In addition, kidneys of fKSC treated rats had an up-regulation of angiogenic proteins hypoxia-inducible factor-1α, VEGF and eNOS on day 3 (P < 0.05).CONCLUSION: Our study shows that fKSC ameliorate cisplatin induced ARF in rats and promote renal angiogenesis, which may be an important therapeutic mechanism of these stem cells in the disease.     

Effect of mechanical ventilation in the prone position on clinical outcomes in patients with acute hypoxemic respiratory failure: a systematic review and meta-analysis

Background

Mechanical ventilation in the prone position is used to improve oxygenation in patients with acute hypoxemic respiratory failure. We sought to determine the effect of mechanical ventilation in the prone position on mortality, oxygenation, duration of ventilation and adverse events in patients with acute hypoxemic respiratory failure.

Methods

In this systematic review we searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and Science Citation Index Expanded for articles published from database inception to February 2008. We also conducted extensive manual searches and contacted experts. We extracted physiologic data and clinically relevant outcomes.

Results

Thirteen trials that enrolled a total of 1559 patients met our inclusion criteria. Overall methodologic quality was good. In 10 of the trials (n = 1486) reporting this outcome, we found that prone positioning did not reduce mortality among hypoxemic patients (risk ratio [RR] 0.96, 95% confidence interval [CI] 0.84–1.09; p = 0.52). The lack of effect of ventilation in the prone position on mortality was similar in trials of prolonged prone positioning and in patients with acute lung injury. In 8 of the trials (n = 633), the ratio of partial pressure of oxygen to inspired fraction of oxygen on day 1 was 34% higher among patients in the prone position than among those who remained supine (p < 0.001); these results were similar in 4 trials on day 2 and in 5 trials on day 3. In 9 trials (n = 1206), the ratio in patients assigned to the prone group remained 6% higher the morning after they returned to the supine position compared with patients assigned to the supine group (p = 0.07). Results were quantitatively similar but statistically significant in 7 trials on day 2 and in 6 trials on day 3 (p = 0.001). In 5 trials (n = 1004), prone positioning was associated with a reduced risk of ventilator-associated pneumonia (RR 0.81, 95% CI 0.66–0.99; p = 0.04) but not with a reduced duration of ventilation. In 6 trials (n = 504), prone positioning was associated with an increased risk of pressure ulcers (RR 1.36, 95% CI 1.07–1.71; p = 0.01). Most analyses found no to moderate between-trial heterogeneity.

Interpretation

Mechanical ventilation in the prone position does not reduce mortality or duration of ventilation despite improved oxygenation and a decreased risk of pneumonia. Therefore, it should not be used routinely for acute hypoxemic respiratory failure. However, a sustained improvement in oxygenation may support the use of prone positioning in patients with very severe hypoxemia, who have not been well-studied to date.Patients with acute lung injury^1,2 and hypoxemic respiratory failure may require mechanical ventilation to maintain oxygenation. Persistent hypoxemia may entail additional treatments, such as inhaled nitric oxide³ or high-frequency oscillation,^4–6 but these treatments are not universally available. In contrast, ventilation in the prone position, first recommended in 1974,⁷ can be readily implemented in any intensive care unit (ICU), and clinicians should be familiar with its effects on patient outcomes.Improved ventilation-perfusion matching is the major physiologic effect of prone positioning for ventilation in patients with acute lung injury.⁸ In the supine position, the dependent dorsal lung regions (compared with nondependent regions) are atelectatic owing to decreased transpulmonary pressure and direct compression by the lungs, heart and abdominal contents (via pressure on a passive diaphragm). Gravity favours increased perfusion to these collapsed dorsal lung segments, which creates shunt conditions. In the prone position, lung compression is decreased, and chest-wall and lung mechanics create more uniform transpulmonary pressure. The previously atelectatic lung thus becomes aerated, and new atelectasis in the now dependent ventral regions is comparatively minor. In addition, lung perfusion in the prone position is more homogeneous. Shunt conditions are therefore reduced and ventilation is better matched to perfusion. Other clinical effects of prone positioning may include enhanced postural drainage of secretions,^9,10 decreasing the risk of ventilator-associated pneumonia. Effects may also include decreased alveolar overdistension, cyclic alveolar collapse and ventilator-induced lung injury.¹¹ For this reason, some investigators have recommended prone positioning for mechanical ventilation in the treatment of acute lung injury.^8,11 Although ventilation in the prone position offers physiologic advantages and does not require specialized tools, one survey found that in most ICUs, 3 personnel (range 2–6) were required to turn an adult patient.¹² These caregivers must handle major safety challenges in putting patients with life-threatening hypoxemia in the prone position, including disconnection or removal of endotracheal tubes or intravascular catheters, and kinking or secretion-induced plugging of endotracheal tubes.¹³ Despite prone positioning''s physiologic advantages, individual randomized controlled trials have not demonstrated its superior clinical outcomes compared with supine positioning. Consequently, we conducted a systematic review and meta-analysis to evaluate the effect of prone positioning on clinical outcomes, including mortality, oxygenation, ventilator-associated pneumonia, duration of ventilation and adverse events, in patients with acute hypoxemic respiratory failure.     

Reduction in post-prandial hyperglycemic excursion through alpha-glucosidase inhibition by beta-acetamido carbonyl compounds

A series of β-acetamido carbonyl compounds (S₁–S₇) were prepared using Dakin-West reaction from different substituted aldehyde and acetophenone in the presence of lanthanum triflate as a solid catalyst. All the compounds were tested for their α-glucosidase inhibitory potential against rat intestinal α-glucosidase. The most potent rat intestinal α-glucosidase inhibitors S₅ and S₇ were tested for their antihyperglycemic activity following carbohydrate tolerance test. Both the compounds displayed antihyperglycemic activity equivalent to the standard drug acarbose.     

Substituted 3-((Z)-2-(4-nitrophenyl)-2-(1H-tetrazol-5-yl) vinyl)-4H-chromen-4-ones as novel anti-MRSA agents: synthesis, SAR, and in-vitro assessment

In search for a new antibacterial agent with improved antimicrobial spectrum and potency, we designed and synthesized a series of novel 3-((Z)-2-(4-nitrophenyl)-2-(1H-tetrazol-5-yl) vinyl)-4H-chromen-4-ones 7a-h by convergent synthesis approach. All the synthesized compounds were assayed for their in-vitro antibacterial activities against gram-negative and gram-positive bacteria. The preliminary structure-activity relationship, to elucidate the essential structure requirements for the antimicrobial activity that results into anti-MRSA (methicillin-resistant S. aureus) potential, has been described. Amongst the synthesized compounds 7d, 7e, 7f and 7h were found to possess activity against methicillin-resistant S. aureus in addition to the activity against other bacterial strains such as E. faecalis, S. pneumoniae, and E. coli.     

Cholesterol depletion modulates basal L-type Ca2+ current and abolishes its -adrenergic enhancement in ventricular myocytes

Cholesterol is a primary constituent of the plasmalemma, including the lipid rafts/caveolae, where various G protein-coupled receptors colocalize with signaling proteins and channels. By manipulating cholesterol in rabbit and rat ventricular myocytes using methyl-beta-cyclodextrin (MbetaCD), we studied the role of cholesterol in the modulation of L-type Ca(2+) currents (I(Ca,L)). MbetaCD was mainly dialyzed from BAPTA-containing pipette solution during whole cell clamp. In rabbit myocytes dialyzed with 30 mM MbetaCD for 10 min, a positive shift in membrane potential at half-maximal activation (V(0.5)) from -8 to -2 mV developed and was associated with an increase in current density at positive potentials (42% at +20 mV vs. time-matched controls). Isoproterenol (ISO) increased I(Ca,L) approximately threefold and caused a negative shift in V(0.5) in control cells, but it did not increase I(Ca,L) in MbetaCD-treated myocytes, nor did it shift V(0.5). The effect of MbetaCD (10 or 30 mM) was concentration dependent: 30 mM MbetaCD suppressed the ISO-induced increase in I(Ca,L) more effectively than 10 mM MbetaCD. MbetaCD dialysis also abolished the increase in I(Ca,L) elicited by forskolin or dibutyryl cAMP, but not that elicited by (-)BAY K 8644. External application of MbetaCD-cholesterol complex to rat myocytes attenuated the MbetaCD-mediated inhibition of the ISO-induced increase of I(Ca,L). Biochemical analysis confirmed that the myocytes' cholesterol content was diminished by MbetaCD and increased by MbetaCD-cholesterol complex. Cholesterol thus appears to contribute to the regulation of basal I(Ca,L) and beta-adrenergic cAMP/PKA-mediated increases in I(Ca,L). We suggest that cholesterol affects the structural coupling between L-type Ca(2+) channels and adjacent regulatory proteins.