Evidence for generation of oxidative stress in brain by MPTP: in vitro and in vivo studies in mice

The role of oxidative stress in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-mediated neurotoxicity is as yet unclear and the evidence for generation of oxygen free radicals as a primary event in the neurotoxicity is yet to be demonstrated. The present study was undertaken to ascertain the potential role of oxidative damage, and the protective role, if any, of the antioxidant, glutathione (GSH), in MPTP-induced neurotoxicity. Exposure of sagittal slices of mouse brain to MPTP resulted in significant increases of reactive oxygen species (ROS) and malondialdehyde (MDA, the product of lipid peroxidation) and decreases in GSH content. Pretreatment of mouse brain slices, in vitro, with GSH or GSH isopropyl ester attenuated MPTP toxicity as assessed by the tissue activity of the mitochondrial enzyme, NADH-dehydrogenase (NADH-DH), and by leakage of the cytosolic enzyme, lactate dehydrogenase (LDH), from the slice into the medium. In vivo administration of MPTP (30 mg/kg body weight, s.c.), to mice resulted in significant lowering of GSH in the striatum and midbrain, 2 h after dosage; ROS levels in the striatum and midbrain increased after 4 and 8 h, respectively. In the striatum significant inhibition of rotenone-sensitive NADH ubiquinone-1 oxido-reductase (Complex 1) was observed transiently 1 h after MPTP administration. The enzyme activity recovered thereafter; significant inhibition of mitochondrial Complex I was observed in the striatum only 18 h after MPTP dose. In the midbrain, mitochondrial Complex I was inhibited only 18 h after MPTP dose; no change was observed at the early time points examined. Thus, the depletion of GSH and increased ROS formation preceded the inhibition of the mitochondrial enzyme in the midbrain. Evidence presented herein from both in vitro and in vivo studies support that MPTP exposure generates ROS resulting in oxidative stress.

Modeling cortisol dynamics in the neuro-endocrine axis distinguishes normal, depression, and post-traumatic stress disorder (PTSD) in humans

Cortisol, secreted in the adrenal cortex in response to stress, is an informative biomarker that distinguishes anxiety disorders such as major depression and post-traumatic stress disorder (PTSD) from normal subjects. Yehuda et al. proposed a hypothesis that, in humans, the hypersensitive hypothalamus-pituitary-adrenal (HPA) axis is responsible for the occurrence of differing levels of cortisol in anxiety disorders. Specifically, PTSD subjects have lower cortisol levels during the late subjective night in comparison to normal subjects, and this was assumed to occur due to strong negative feedback loops in the HPA axis. In the present work, to address this hypothesis, we modeled the cortisol dynamics using nonlinear ordinary differential equations and estimated the kinetic parameters of the model to fit the experimental data of three categories, namely, normal, depressed, and PTSD human subjects. We concatenated the subjects (n = 3) in each category and created a model subject (n = 1) without considering the patient-to-patient variability in each case. The parameters of the model for the three categories were simultaneously obtained through global optimization. Bifurcation analysis carried out with the optimized parameters exhibited two supercritical Hopf points and, for the choice of parameters, the oscillations were found to be circadian in nature. The fitted kinetic parameters indicate that PTSD subjects have a strong negative feedback loop and, as a result, the predicted oscillating cortisol levels are extremely low at the nadir in contrast to normal subjects, albeit within the endocrinologic range. We also simulated the phenotypes for each of the categories and, as observed in the clinical data of PTSD patients, the simulated cortisol levels are consistently low at the nadir, and correspondingly the negative feedback was found to be extremely strong. These results from the model support the hypothesis that high stress intensity and strong negative feedback loop may cause hypersensitive neuro-endocrine axis that results in hypocortisolemia in PTSD.

PTSD is an anxiety disorder that occurs among persons exposed to a traumatic event involving life threat and injury. This is a co-morbid psychiatric disorder that occurs along with depression. Cortisol is an informative endocrine biomarker that can distinguish PTSD from other co-morbid disorders. In comparison to normal subjects, hypocortisolemia was observed during the night in PTSD, while hypercortisolemia was observed in depressed subjects. From analyzing the clinical data, Yehuda et al. hypothesized that hypocortisolemia in PTSD was due to the strong negative feedback loop operating in the neuroendocrine axis under severe stress. We complemented this hypothesis by constructing a mathematical model for cortisol dynamics in HPA axis and estimated the kinetic parameters that fitted the cortisol time series obtained from the clinical data of normal, depressed and PTSD patients. The parameters obtained from the simulated phenotypes also strongly support the hypothesis that, due to disruptive negative feedback loops, cortisol levels are different in normal, PTSD and depressed subjects during the night. Importantly, the model predicted the transitions from normal to various diseased states, and these transitions were shown to occur due to changes in the strength of the negative feedback loop and the stress intensity in the neuro-endocrine axis.

Compositional complementarity and prebiotic ecology in the origin of life

We hypothesize that life began not with the first self-reproducing molecule or metabolic network, but as a prebiotic ecology of co-evolving populations of macromolecular aggregates (composomes). Each composome species had a particular molecular composition resulting from molecular complementarity among environmentally available prebiotic compounds. Natural selection acted on composomal species that varied in properties and functions such as stability, catalysis, fission, fusion and selective accumulation of molecules from solution. Fission permitted molecular replication based on composition rather than linear structure, while fusion created composomal variability. Catalytic functions provided additional chemical novelty resulting eventually in autocatalytic and mutually catalytic networks within composomal species. Composomal autocatalysis and interdependence allowed the Darwinian co-evolution of content and control (metabolism). The existence of chemical interfaces within complex composomes created linear templates upon which self-reproducing molecules (such as RNA) could be synthesized, permitting the evolution of informational replication by molecular templating. Mathematical and experimental tests are proposed.

Bedside emergency ultrasonographic diagnosis of diaphragmatic rupture in blunt abdominal trauma

Abdominal injury from significant blunt trauma can include injury to bowel, kidneys, liver, and spleen. In approximately 5% of all injuries one of the diaphragms is ruptured. Diaphragmatic rupture may not be easily detected and this can lead to significant morbidity and even mortality. Rupture may be suggested on chest X-ray film especially with abnormal nasogastric tube location but the accuracy of this method is modest only. Abdominal computed tomography is not accurate and magnetic resonance imaging, although very sensitive and specific, is not feasible in most trauma situations. Surgeons have often resorted to exploratory laparotomy or laparoscopy to make the diagnosis. Although not typically part of the basic Focused Abdominal Sonography for Trauma (FAST) examination, ultrasonographic diagnosis of diaphragmatic rupture is possible with little added time to the examination. We present 3 cases of diaphragmatic rupture discovered shortly after the patients' arrival, on initial trauma evaluation with the FAST. A discussion of previous literature and ultrasound technique for diagnosis follows the cases.

Short-course chemotherapy for tuberculosis of the spine. A comparison between ambulant treatment and radical surgery--ten-year report

We performed a randomised, controlled clinical trial to compare ambulant short-course chemotherapy with anterior spinal fusion plus short-course chemotherapy for spinal tuberculosis without paraplegia. Patients with active disease of vertebral bodies were randomly allocated to one of three regimens: a) radical anterior resection with bone grafting plus six months of daily isoniazid plus rifampicin (Rad6); b) ambulant chemotherapy for six months with daily isoniazid plus rifampicin (Amb6); or c) similar to b) but with chemotherapy for nine months (Amb9). Ten years from the onset of treatment, 90% of 78 Rad6, 94% of 78 Amb6 and 99% of 79 Amb9 patients had a favourable status. Ambulant chemotherapy for a period of six months with daily isoniazid plus rifampicin (Amb6) was an effective treatment for spinal tuberculosis except in patients aged less than 15 years with an initial angle of kyphosis of more than 30 degrees whose kyphosis increased substantially.

Obesity exacerbates chemically induced neurodegeneration

Obesity is a major risk factor associated with a variety of human disorders. While its involvement in disorders such as diabetes, coronary heart disease and cancer have been well characterized, it remains to be determined if obesity has a detrimental effect on the nervous system. To address this issue we determined whether obesity serves as a risk factor for neurotoxicity. Model neurotoxicants, methamphetamine (METH) and kainic acid (KA), which are known to cause selective neurodegeneration of anatomically distinct areas of the brain, were evaluated using an animal model of obesity, the ob/ob mouse. Administration of METH and KA resulted in mortality among ob/ob mice but not among their lean littermates. While METH caused dopaminergic nerve terminal degeneration as indicated by decreased striatal dopamine (49%) and tyrosine hydroxylase protein (68%), as well as an increase in glial fibrillary acidic protein by 313% in the lean mice, these effects were exacerbated under the obese condition (96%, 86% and 602%, respectively). Similarly, a dosage of KA that did not increase glial fibrillary acidic protein in lean mice increased the hippocampal content of this protein (93%) in ob/ob mice. KA treatment resulted in extensive neuronal degeneration as determined by Fluoro-Jade B staining, decreased hippocampal microtubule-associated protein-2 immunoreactivity and increased reactive gliosis in ob/ob mice. The neurotoxic outcome in ob/ob mice remained exacerbated even when lean and ob/ob mice were dosed with METH or KA based only on a lean body mass. Administration of METH or KA resulted in up-regulation of the mitochondrial uncoupling protein-2 to a greater extent in the ob/ob mice, an effect known to reduce ATP yield and facilitate oxidative stress and mitochondrial dysfunction. These events may underlie the enhanced neurotoxicity seen in the obese mice. In summary, our results implicate obesity as a risk factor associated with chemical- and possibly disease-induced neurodegeneration.

Prophylactic locking of enteral feeding tubes with pancreatic enzymes

BACKGROUND

Obstruction of feeding tubes is a common mechanical complication associated with enteral feeding. Standard methods of flushing are not always effective.

METHODS

This study was conducted with patients receiving enteral feeding via nasogastric, nasoenteral, gastrostomy, or jejunostomy tubes to determine if prophylactic use of pancreatic enzymes would maintain patency of feeding tubes. Interrupted feeding regimens were used. Control patients (n = 24) received only water for flushing. After water flushing of the tube, study patients (n = 33) received a 5-mL suspension of pancreatic enzyme containing the following enzyme activity (in Federation Internationale Pharmaceutique [FIP] units): lipase, 2000; amylase, 1500; and protease, 100. The suspension also contained 90 mg of NaHCO3 to maintain a pH of 7.5. The mean duration of observation in the control and study groups was 25 and 48 days, respectively.

RESULTS

Compared with eight episodes (23.5%) of tube occlusions in the control group (n = 34), there was only one episode (2.6%) in the study group (n = 38). This difference was significant by the test of proportions (z = 2.68, p = .01).

CONCLUSIONS

In addition to routine water flushing, the routine prophylactic use of pancreatic enzyme-sodium bicarbonate suspension (pH 7.5) prevents occlusion of feeding tubes.

Suppression of Endothelial AGO1 Promotes Adipose Tissue Browning and Improves Metabolic Dysfunction

BACKGROUND

Metabolic disorders such as obesity and diabetes mellitus can cause dysfunction of endothelial cells (ECs) and vascular rarefaction in adipose tissues. However, the modulatory role of ECs in adipose tissue function is not fully understood. Other than vascular endothelial growth factor-vascular endothelial growth factor receptor-mediated angiogenic signaling, little is known about the EC-derived signals in adipose tissue regulation. We previously identified Argonaute 1 (AGO1; a key component of microRNA-induced silencing complex) as a crucial regulator in hypoxia-induced angiogenesis. In this study, we intend to determine the AGO1-mediated EC transcriptome, the functional importance of AGO1-regulated endothelial function in vivo, and the relevance to adipose tissue function and obesity.

METHODS

We generated and subjected mice with EC-AGO1 deletion (EC-AGO1-knockout [KO]) and their wild-type littermates to a fast food-mimicking, high-fat high-sucrose diet and profiled the metabolic phenotypes. We used crosslinking immunoprecipitation- and RNA-sequencing to identify the AGO1-mediated mechanisms underlying the observed metabolic phenotype of EC-AGO1-KO. We further leveraged cell cultures and mouse models to validate the functional importance of the identified molecular pathway, for which the translational relevance was explored using human endothelium isolated from healthy donors and donors with obesity/type 2 diabetes mellitus.

RESULTS

We identified an antiobesity phenotype of EC-AGO1-KO, evident by lower body weight and body fat, improved insulin sensitivity, and enhanced energy expenditure. At the organ level, we observed the most significant phenotype in the subcutaneous and brown adipose tissues of KO mice, with greater vascularity and enhanced browning and thermogenesis. Mechanistically, EC-AGO1 suppression results in inhibition of thrombospondin-1 (THBS1/TSP1), an antiangiogenic and proinflammatory cytokine that promotes insulin resistance. In EC-AGO1-KO mice, overexpression of TSP1 substantially attenuated the beneficial phenotype. In human endothelium isolated from donors with obesity or type 2 diabetes mellitus, AGO1 and THBS1 are expressed at higher levels than the healthy controls, supporting a pathological role of this pathway.

CONCLUSIONS

Our study suggests a novel mechanism by which ECs, through the AGO1-TSP1 pathway, control vascularization and function of adipose tissues, insulin sensitivity, and whole-body metabolic state.

Short-course chemotherapy for tuberculosis of the spine

We performed a randomised, controlled clinical trial to compare ambulant short-course chemotherapy with anterior spinal fusion plus short-course chemotherapy for spinal tuberculosis without paraplegia. Patients with active disease of vertebral bodies were randomly allocated to one of three regimens: a) radical anterior resection with bone grafting plus six months of daily isoniazid plus rifampicin (Rad6); b) ambulant chemotherapy for six months with daily isoniazid plus rifampicin (Amb6); or c) similar to b) but with chemotherapy for nine months (Amb9).

Ten years from the onset of treatment, 90% of 78 Rad6, 94% of 78 Amb6 and 99% of 79 Amb9 patients had a favourable status.

Ambulant chemotherapy for a period of six months with daily isoniazid plus rifampicin (Amb6) was an effective treatment for spinal tuberculosis except in patients aged less than 15 years with an initial angle of kyphosis of more than 30° whose kyphosis increased substantially.

A two variable delay model for the circadian rhythm of Neurospora crassa

A two variable model with delay in both the variables, is proposed for the circadian oscillations of protein concentrations in the fungal species Neurospora crassa. The dynamical variables chosen are the concentrations of FRQ and WC-1 proteins. Our model is a two variable simplification of the detailed model of Smolen et al. (J. Neurosci. 21 (2001) 6644) modeling circadian oscillations with interlocking positive and negative feedback loops, containing 23 variables. In our model, as in the case of Smolen's model, a sustained limit cycle oscillation takes place in both FRQ and WC-1 protein in continuous darkness, and WC-1 is anti-phase to FRQ protein, as observed in experiments. The model accounts for various characteristic features of circadian rhythms such as entrainment to light dark cycles, phase response curves and robustness to parameter variation and molecular fluctuations. Simulations are carried out to study the effect of periodic forcing of circadian oscillations by light-dark cycles. The periodic forcing resulted in a rich bifurcation diagram that includes quasiperiodicity and chaotic oscillations, depending on the magnitude of the periodic changes in the light controlled parameter. When positive feedback is eliminated, our model reduces to the generic one dimensional delay model of Lema et al. (J. Theor. Biol. 204 (2000) 565), delay model of the circadian pace maker with FRQ protein as the dynamical variable which represses its own production. This one-dimensional model also exhibits all characteristic features of circadian oscillations and gives rise to circadian oscillations which are reasonably robust to parameter variations and molecular noise.

Suppression of appetite by parenteral nutrition in humans

The effects of parenteral nutrition on appetite during and after therapy are unclear. Previous studies done in animals, as well as in humans, are inconclusive. The purpose of this study was to investigate the effects of parenteral nutrition on voluntary oral intake of food. The study was done on ten stable patients receiving parenteral nutrition for transient dysfunction of their gastrointestinal tract. For each patient, a calorie count of the ingested food was obtained for 3 consecutive days. Parenteral calories were then decreased without the patient's knowledge. A calorie count for 3 more days was obtained following the day of change. The mean daily oral intake was 823 kcal when the mean daily parenteral nutrition intake was 2,902, providing a total of 3,723 kcal. When parenteral nutrition calories were decreased to a mean of 1,550, the mean daily oral intake increased to 1,396. This difference in oral and parenteral calorie intake was statistically significant (P less than .001). It can be concluded from this data that parenteral nutrition decreases voluntary oral intake of food. It is therefore suggested that if the gastrointestinal tract is functionally satisfactory, parenteral nutrition can be rapidly weaned off, provided oral consumption is monitored to assure adequacy.

Myocardial fibrosis: role of angiotensin II and aldosterone

In this report we review the replacement (i.e., scarring) and reactive (i.e., perivascular and interstitial fibrosis) fibrous tissue responses found in the myocardium in response to effector hormones of the renin-angiotensin-aldosterone system. Experimental data are presented to indicate: a) endogenous or exogenous elevations in plasma angiotensin II are associated with acute cardiac myocyte necrosis and subsequent microscopic scarring; b) chronic elevations in plasma aldosterone (ALDO), relative to Na+ intake, are associated with a perivascular and interstitial fibrosis of the coronary and systemic circulations and are also seen in response to chronic administration of the mineralocorticoid hormone deoxycorticosterone (DOC); and c) chronic mineralocorticoid excess, due to ALDO or DOC, is associated with enhanced urinary K+ excretion, cardiac myocyte necrosis and scarring. Pharmacologic agents which interfere with these effector hormones (e.g., ACE inhibition and ALDO receptor antagonism) protect the myocardium against this pathologic structural remodeling created by the reactive and replacement (reparative) fibrosis. Evidence is also presented to indicate that chronic ACE inhibition is associated with a regression in reactive myocardial fibrosis. Based on these experimental findings we would suggest that clinical trials are indicated to address the prevention and regression of myocardial fibrosis--an important determinant of pathologic structural remodeling and abnormal myocardial stiffness.

Revealing protein-protein interactions at the transcriptome scale by sequencing

We describe PROPER-seq (protein-protein interaction sequencing) to map protein-protein interactions (PPIs) en masse. PROPER-seq first converts transcriptomes of input cells into RNA-barcoded protein libraries, in which all interacting protein pairs are captured through nucleotide barcode ligation, recorded as chimeric DNA sequences, and decoded at once by sequencing and mapping. We applied PROPER-seq to human embryonic kidney cells, T lymphocytes, and endothelial cells and identified 210,518 human PPIs (collected in the PROPER v.1.0 database). Among these, 1,365 and 2,480 PPIs are supported by published co-immunoprecipitation (coIP) and affinity purification-mass spectrometry (AP-MS) data, 17,638 PPIs are predicted by the prePPI algorithm without previous experimental validation, and 100 PPIs overlap human synthetic lethal gene pairs. In addition, four previously uncharacterized interaction partners with poly(ADP-ribose) polymerase 1 (PARP1) (a critical protein in DNA repair) known as XPO1, MATR3, IPO5, and LEO1 are validated in vivo. PROPER-seq presents a time-effective technology to map PPIs at the transcriptome scale, and PROPER v.1.0 provides a rich resource for studying PPIs.

Neutropenia due to copper deficiency in total parenteral nutrition

Copper (Cu) deficiency has been reported both in pediatric and adult patients on total parenteral nutrition (TPN). Manifestations of Cu deficiency are usually hematologic in the adult. A 56-yr-old patient with a history of subtotal gastrectomy underwent massive small bowel resection and partial colectomy in 1977. TPN was initiated. Intravenous (iv) trace mineral supplements were not available in 1977 at our institution. By June 1978, the patient manifested neutropenia with a white blood cell (WBC) count of 2000/mm3 and 39% neutrophils or a total neutrophil count (TNC) of 780/mm3. The serum Cu level at that time was 5 micrograms/dl (normal, 70-140), and the serum zinc (Zn) level was low, although within normal limits. Oral supplementation with Cu and Zn tablets proved ineffective. Twice weekly infusions of fresh frozen plasma were begun in April 1979, and intravenous chromium supplementation started in September 1979, but neither the WBC count nor the TNC improved. Intravenous Cu and Zn were approved in October 1979, and were added to the TPN formula. Within 2 weeks, the WBC count rose to 6300/mm3, and the neutrophils increased to 83% with a TNC of 5229. After 12 weeks, the serum Cu level rose to 80 micrograms/dl. The increase in WBC count and percentage of neutrophils can be attributed to the addition of Cu to the TPN infusate.

Retrospective Analysis of Ossifying Fibroma of Jaw Bones Over a Period of 10 Years with Literature Review

OBJECTIVE

The purpose of this retrospective analysis is to document and discuss the features, treatment rendered and result of 25 histologically proven cases of ossifying fibromas of jaw bones operated by a single surgeon over a period of 10 years.

MATERIALS AND METHODS

The records of ossifying fibroma were obtained from the archives of Oral and Maxillofacial Surgery at Maulana Azad Institute of Dental Sciences (MAIDS) from 2001 to 2011. Only those cases were included in the study where definitive surgery was performed based on clinical, radiological & histopathological features.

RESULTS

Twenty-five patients were analyzed with a final diagnosis of ossifying fibroma comprising of 14 males (56 %) and 11 females (44 %). The age range was 11-45 years with a mean of 24.12 years. Mandible was involved in 72 % and maxilla in 28 % cases with a predominance of mandibular posterior [19 (76 %)] cases. The study showed similar findings in regard to clinical, radiographic & histological features of ossifying fibroma as compared to other studies. It also showed that the treatment rendered in the form of eneucleation, curettage or resection of the lesion depending on its stage and extent were adequate, as no recurrence has been reported till date.

CONCLUSION

Enucleation is preferred in small and well demarcated lesions. Curettage should be done in relatively large lesions with ill defined borders, not involving basal bone of mandible or cortical perforation. Resection should be reserved for aggressive and extensive cases with involvement of basal bone or perforation of cortices.

Phenothiazine effect on gastrointestinal tract function

Clinical evidence indicates that phenothiazines, specifically chlorpromazine (CPZ), used extensively in the treatment of patients with mental and/or neurologic disorders produce an ileus characterized by pseudoobstruction with an extended barium transit time of eight to ten days. Postoperatively, these patients have a protracted ileus, lasting from ten to fourteen days. In our present study we investigated the mechanism of action by which phenothiazines block gastrointestinal tract function as well as the possible reversal of this effect by pharmacologic agents. Guinea pigs were injected intraperitoneally with CPZ at a dose of 30 mg/kg/day for five to seventeen days. This caused deleterious effects in the gastrointestinal tract, such as cessation of peristalsis of small intestine and colon, and marked distension of the cecum. In vitro pharmacologic studies were performed on the electrically stimulated longitudinal muscle-myenteric plexus of the guinea pigs. We found that phenothiazines interfered with the neuromuscular mechanism of the intestine, as exemplified by a lack of response to electrical current stimulation. The effect was protracted, lasting at least 24 hours. These effects were reversed by the administration of the anticholinesterase, physostigmine (PGM), provided the block was less than 80 per cent. The paralytic ileus produced was similar to that found in man.

Dynamics of the interlocked positive feedback loops explaining the robust epigenetic switching in Candida albicans

The two element mutual activation and inhibitory positive feedback loops are a common motifs that occur in many biological systems in both isolated and interlocked form, as for example, in the cell division cycle and thymus differentiation in eukaryotes. The properties of three element interlocked positive feedback loops that embeds both mutual activation and inhibition are studied in depth for their bistable properties by performing bifurcation and stochastic simulations. Codimension one and two bifurcations reveal important properties like robustness to parameter variations and adaptability under various conditions by its ability to fine tune the threshold to a wide range of values and to maintain a wide bistable regime. Furthermore, we show that in the interlocked circuit, mutual inhibition controls the decision to switch from OFF to ON state, while mutual activation enforces the decision. This view is supported through a concrete biological example Candida albicans, a human fungal pathogen that can exist in two distinctive cell types; one in the default white state and the other in an opaque form. Stochastic switching between these two forms takes place due to the epigenetic alternation induced by the transcriptional regulators in the circuit, albeit without any rearrangement of the nuclear chromosomes. The transcriptional regulators constitute interlocked mutual activation and inhibition feedback circuits that provide adaptable threshold and wide bistable regime. These positive feedback loops are shown to be responsible for robust noise induced transitions without chattering, persistence of particular phenotypes for many generations and selective exhibition of one particular form of phenotype when mutated. Finally, we propose for synthetic biology constructs to use interlocked positive feedback loops instead of two element positive feedback loops because they are better controlled than isolated mutual activation and mutual inhibition feedback circuits.

Long noncoding RNA LEENE promotes angiogenesis and ischemic recovery in diabetes models

Impaired angiogenesis in diabetes is a key process contributing to ischemic diseases such as peripheral arterial disease. Epigenetic mechanisms, including those mediated by long noncoding RNAs (lncRNAs), are crucial links connecting diabetes and the related chronic tissue ischemia. Here we identify the lncRNA that enhances endothelial nitric oxide synthase (eNOS) expression (LEENE) as a regulator of angiogenesis and ischemic response. LEENE expression was decreased in diabetic conditions in cultured endothelial cells (ECs), mouse hind limb muscles, and human arteries. Inhibition of LEENE in human microvascular ECs reduced their angiogenic capacity with a dysregulated angiogenic gene program. Diabetic mice deficient in Leene demonstrated impaired angiogenesis and perfusion following hind limb ischemia. Importantly, overexpression of human LEENE rescued the impaired ischemic response in Leene-knockout mice at tissue functional and single-cell transcriptomic levels. Mechanistically, LEENE RNA promoted transcription of proangiogenic genes in ECs, such as KDR (encoding VEGFR2) and NOS3 (encoding eNOS), potentially by interacting with LEO1, a key component of the RNA polymerase II-associated factor complex and MYC, a crucial transcription factor for angiogenesis. Taken together, our findings demonstrate an essential role for LEENE in the regulation of angiogenesis and tissue perfusion. Functional enhancement of LEENE to restore angiogenesis for tissue repair and regeneration may represent a potential strategy to tackle ischemic vascular diseases.

A detailed modular analysis of heat-shock protein dynamics under acute and chronic stress and its implication in anxiety disorders

Physiological and psychological stresses cause anxiety disorders such as depression and post-traumatic stress disorder (PTSD) and induce drastic changes at a molecular level in the brain. To counteract this stress, the heat-shock protein (HSP) network plays a vital role in restoring the homeostasis of the system. To study the stress-induced dynamics of heat-shock network, we analyzed three modules of the HSP90 network—namely trimerization reactions, phosphorylation–dephosphorylation reactions, and the conversion of HSP90 from an open to a closed conformation—and constructed a corresponding nonlinear differential equation model based on mass action kinetics laws. The kinetic parameters of the model were obtained through global optimization, and sensitivity analyses revealed that the most sensitive parameters are the kinase and phosphatase that drive the phosphorylation–dephosphorylation reactions. Bifurcation analysis carried out with the estimated kinetic parameters of the model with stress as bifurcation parameter revealed the occurrence of “mushroom”, a type of complex dynamics in which S-shaped and Z-shaped hysteretic bistable forms are present together. We mapped the molecular events responsible for generating the mushroom dynamics under stress and interpreted the occurrence of the S-shaped hysteresis to a normal level of stress, and the Z-shaped hysteresis to the HSP90 variations under acute and chronic stress in the fear conditioned system, and further, we hypothesized that this can be extended to stress-related disorders such as depression and PTSD in humans. Finally, we studied the effect of parameter variations on the mushroom dynamics to get insight about the role of phosphorylation–dephosphorylation parameters in HSP90 network in bringing about complex dynamics such as isolas, where the stable steady states in a bistable system are isolated and separated from each other and not connected by an unstable steady state.

Question 7: the first units of life were not simple cells

Five common assumptions about the first cells are challenged by the pre-biotic ecology model and are replaced by the following propositions: firstly, early cells were more complex, more varied and had a greater diversity of constituents than modern cells; secondly, the complexity of a cell is not related to the number of genes it contains, indeed, modern bacteria are as complex as eukaryotes; thirdly, the unit of early life was an 'ecosystem' rather than a 'cell'; fourthly, the early cell needed no genes at all; fifthly, early life depended on non-covalent associations and on catalysts that were not confined to specific reactions. We present here the outlines of a theory that connects findings about modern bacteria with speculations about their origins.

Structural analysis to determine the core of hypoxia response network

The advent of sophisticated molecular biology techniques allows to deduce the structure of complex biological networks. However, networks tend to be huge and impose computational challenges on traditional mathematical analysis due to their high dimension and lack of reliable kinetic data. To overcome this problem, complex biological networks are decomposed into modules that are assumed to capture essential aspects of the full network's dynamics. The question that begs for an answer is how to identify the core that is representative of a network's dynamics, its function and robustness. One of the powerful methods to probe into the structure of a network is Petri net analysis. Petri nets support network visualization and execution. They are also equipped with sound mathematical and formal reasoning based on which a network can be decomposed into modules. The structural analysis provides insight into the robustness and facilitates the identification of fragile nodes. The application of these techniques to a previously proposed hypoxia control network reveals three functional modules responsible for degrading the hypoxia-inducible factor (HIF). Interestingly, the structural analysis identifies superfluous network parts and suggests that the reversibility of the reactions are not important for the essential functionality. The core network is determined to be the union of the three reduced individual modules. The structural analysis results are confirmed by numerical integration of the differential equations induced by the individual modules as well as their composition. The structural analysis leads also to a coarse network structure highlighting the structural principles inherent in the three functional modules. Importantly, our analysis identifies the fragile node in this robust network without which the switch-like behavior is shown to be completely absent.

The efficacy of nutritional support in the elderly

One hundred two consecutively nutritionally supported patients were studied to determine the effect of age on the response to nutritional support and outcome of hospital stay. The patients were divided into two groups: group 1 (n = 37) consisted of all patients under 65 years of age, and group 2 (n = 65) consisted of patients 65 years of age and older. All patients underwent a complete nutritional assessment prior to the initiation of nutritional support and weekly thereafter. The patients' somatic compartments were assessed using weight, arm muscle circumference, creatinine height index, and triceps skinfold thickness. The visceral compartments were assessed using serum albumin level, transferrin total iron binding capacity (TIBC) level, and total lymphocyte count. Nitrogen balance was evaluated and cell-mediated immunity was determined using a standard battery of antigens. The patients' nutritional assessment parameters at the start of therapy were compared with those at discharge or death and correlated with outcome of hospital stay. The difference in crude mortality rates between the two groups was statistically significant; however, there was no significant difference between the type and degree of nutritional depletion and mean length of nutritional therapy between the two groups. There was also no significant difference between the degree of improvement or maintenance of somatic or visceral parameters, nitrogen balance, or cell-mediated immunity between the two groups. It is therefore concluded that age alone is not a deterrent to the use of aggressive nutritional support in the elderly.