Thermodynamic parameters for an expanded nearest-neighbor model for formation of RNA duplexes with Watson-Crick base pairs

Improved thermodynamic parameters for prediction of RNA duplex formation are derived from optical melting studies of 90 oligoribonucleotide duplexes containing only Watson-Crick base pairs. To test end or base composition effects, new sets of duplexes are included that have identical nearest neighbors, but different base compositions and therefore different ends. Duplexes with terminal GC pairs are more stable than duplexes with the same nearest neighbors but terminal AU pairs. Penalizing terminal AU base pairs by 0.45 kcal/mol relative to terminal GC base pairs significantly improves predictions of DeltaG degrees37 from a nearest-neighbor model. A physical model is suggested in which the differential treatment of AU and GC ends accounts for the dependence of the total number of Watson-Crick hydrogen bonds on the base composition of a duplex. On average, the new parameters predict DeltaG degrees37, DeltaH degrees, DeltaS degrees, and TM within 3.2%, 6.0%, 6.8%, and 1.3 degreesC, respectively. These predictions are within the limit of the model, based on experimental results for duplexes predicted to have identical thermodynamic parameters.

Highly Efficient Lead Distribution by Magnetic Sewage Sludge Biochar: Sorption Mechanisms and Bench Applications

Highly efficient magnetic sewage sludge biochar (MSSBC) discloses feasible fabrication process with lower production cost, superior adsorption capacity, usage of waste sewage sludge as resource, selected by external magnetic field and exceptional regeneration property. 2gL^-1 MSSBC exhibited a high adsorption capacity of 249.00mgg^-1 in 200ppmPb(II) and the lead-MSSBC equilibrium was achieved within one hour, owing to the existence of the copious active sites. The adsorption kinetics was well described by the pseudo-second-order model while the adsorption isotherm could be fitted by Langmuir model. Mechanism study demonstrated the adsorption involved electrostatic attraction, ion exchange, inner-sphere complexation and formation of co-precipitates at the surface of MSSBC. Additionally, adsorption performance maintained remarkable in a broad pH window. These outcomes demonstrated the promising waste resource utilization by a feasible approach that turns the solid waste of sewage sludge into biochar adsorbent with auspicious applications in elimination of Pb(II) from wastewater.

MicroRNAs and cancer stem cells: the sword and the shield

Emerging chemotherapy drugs and targeted therapies have been widely applied in anticancer treatment and have given oncologists a promising future. Nevertheless, regeneration and recurrence are still huge obstacles on the way to cure cancer. Cancer stem cells (CSCs) are capable of self-renewal, tumor initiation, recurrence, metastasis, therapy resistance, and reside as a subset in many, if not all, cancers. Therefore, therapeutics specifically targeting and killing CSCs are being identified, and may be promising and effective strategies to eliminate cancer. MicroRNAs (miRNAs, miRs), small noncoding RNAs regulating gene expression in a post-transcriptional manner, are dysregulated in most malignancies and are identified as important regulators of CSCs. However, limited knowledge exists for biological and molecular mechanism by which miRNAs regulate CSCs. In this article, we review CSCs, miRNAs and the interactions between miRNA regulation and CSCs, with a specific focus on the molecular mechanisms and clinical applications. This review will help us to know in detail how CSCs are regulated by miRNAs networks and also help to develop more effective and secure miRNA-based clinical therapies.

Facile One-Pot Synthesis of Sustainable Carboxymethyl Chitosan - Sewage Sludge Biochar for Effective Heavy Metal Chelation and Regeneration

In this paper, sewage sludge, a solid waste from wastewater treatment plant, which eagerly requires proper treatment was reused as solid support in the form of sewage sludge biochar, then modified with carboxymethyl chitosan to form a bio-adsorbent. Further, carboxymethyl chitosan coating on sewage sludge biochar improved carboxymethyl chitosan's stability in water. The prepared bio-adsorbent revealed a shorter equilibrium time (<60 min) for Pb(II) adsorption and a superior capacity of 594.17 mg g^-1 for Hg(II) adsorption, which are so far the best recorded performance achieved for chitosan based adsorbents. Additionally, the adsorbent was highly selective for heavy metal ions and it also presented a good stability and reusability for industrial applications. These outcomes demonstrate waste valorization through a green, facile and one-pot approach that turns the solid waste of sewage sludge into biochar adsorbent with propitious applications in the elimination of heavy metal ions from wastewater.

Systems analysis of phosphate-limitation-induced lipid accumulation by the oleaginous yeast Rhodosporidium toruloides

BACKGROUND

Lipid accumulation by oleaginous microorganisms is of great scientific interest and biotechnological potential. While nitrogen limitation has been routinely employed, low-cost raw materials usually contain rich nitrogenous components, thus preventing from efficient lipid production. Inorganic phosphate (Pi) limitation has been found sufficient to promote conversion of sugars into lipids, yet the molecular basis of cellular response to Pi limitation and concurrent lipid accumulation remains elusive.

RESULTS

Here, we performed multi-omic analyses of the oleaginous yeast Rhodosporidium toruloides to shield lights on Pi-limitation-induced lipid accumulation. Samples were prepared under Pi-limited as well as Pi-repleted chemostat conditions, and subjected to analysis at the transcriptomic, proteomic, and metabolomic levels. In total, 7970 genes, 4212 proteins, and 123 metabolites were identified. Results showed that Pi limitation facilitates up-regulation of Pi-associated metabolism, RNA degradation, and triacylglycerol biosynthesis while down-regulation of ribosome biosynthesis and tricarboxylic acid cycle. Pi limitation leads to dephosphorylation of adenosine monophosphate and the allosteric activator of isocitrate dehydrogenase key to lipid biosynthesis. It was found that NADPH, the key cofactor for fatty acid biosynthesis, is limited due to reduced flux through the pentose phosphate pathway and transhydrogenation cycle and that this can be overcome by over-expression of an endogenous malic enzyme. These phenomena are found distinctive from those under nitrogen limitation.

CONCLUSIONS

Our data suggest that Pi limitation activates Pi-related metabolism, RNA degradation, and TAG biosynthesis while inhibits ribosome biosynthesis and TCA cycle, leading to enhanced carbon fluxes into lipids. The information greatly enriches our understanding on microbial oleaginicity and Pi-related metabolism. Importantly, systems data may facilitate designing advanced cell factories for production of lipids and related oleochemicals.

Transcriptome profiling of the whitefly Bemisia tabaci reveals stage-specific gene expression signatures for thiamethoxam resistance

Bemisia tabaci has developed high levels of resistance to many insecticides including the neonicotinoids and there is strong evidence that for some compounds resistance is stage-specific. To investigate the molecular basis of B. tabaci resistance to the neonicotinoid thiamethoxam we used a custom whitefly microarray to compare gene expression in the egg, nymph and adult stages of a thiamethoxam-resistant strain (TH-R) with a susceptible strain (TH-S). Gene ontology and bioinformatic analyses revealed that in all life stages many of the differentially expressed transcripts encoded enzymes involved in metabolic processes and/or metabolism of xenobiotics. Several of these are candidate resistance genes and include the cytochrome P450 CYP6CM1, which has been shown to confer resistance to several neonicotinoids previously, a P450 belonging to the Cytochrome P450s 4 family and a glutathione S-transferase (GST) belonging to the sigma class. Finally several ATP-binding cassette transporters of the ABCG subfamily were highly over-expressed in the adult stage of the TH-R strain and may play a role in resistance by active efflux. Here, we evaluated both common and stage-specific gene expression signatures and identified several candidate resistance genes that may underlie B. tabaci resistance to thiamethoxam.

Somatic mutations in the Notch, NF-KB, PIK3CA, and Hedgehog pathways in human breast cancers

Exome sequencing of human breast cancers has revealed a substantial number of candidate cancer genes with recurring but infrequent somatic mutations. To determine more accurately their mutation prevalence, we performed a mutation analysis of 36 novel candidate cancer genes in 96 human breast cancers. Somatic mutations with potential impact on protein function were observed in the genes ADAM12, CENTB1, CENTG1, DIP2C, GLI1, GRIN2D, HDLBP, IKBKB, KPNA5, NFKB1, NOTCH1, and OTOF. These findings strengthen the evidence for involvement of the Notch, Hedgehog, NF-KB, and PIK3CA pathways in breast cancer development, and point to novel processes that likely are involved.

Fast and efficient genetic transformation of oleaginous yeast Rhodosporidium toruloides by using electroporation

Metabolic engineering of Rhodosporidium toruloides, a robust lipid and caroteinoid producer, is of great importance for oleochemicals and carotenoids production. However, the Agrobacterium-mediated gene transformation is tedious and time consuming. Here, we described a fast and efficient genetic transformation of R. toruloides using electroporation with linear DNA fragments, and the process was optimized. The results showed that 2 × 103 transformants can be obtained at 0.7 kV/μg linear DNA by using hygromycin and bleomycin as selection markers after the competent cells pretreated with 25 mM DTT and 100 mM LiAc. Our results would facilitate mutant library construction and metabolic engineering of R. toruloides for production of oleochemicals and carotenoids. We further demonstrated that all transformants arose due to illegitimate integration of transforming DNA fragments by colony PCR.

Alcohol consumption alters dopamine transporter sites in Wistar–Kyoto rat brain

Even though animal and human studies show alterations in dopamine transporter (DAT) sites after alcohol withdrawal, the role of DAT in influencing either alcoholic or depressive behavior has not been examined extensively. Given that the Wistar-Kyoto (WKY) rat is a putative animal model of depressive behavior, the present study examined the effects of chronic alcohol consumption on DAT sites in WKY versus Wistar (WIS) rats. Brains from both strains were sectioned for autoradiographic analysis of [3H]-GBR12935 binding to DAT sites after 24 days of alcohol exposure. The results indicated that WKY rats consumed a greater amount of alcohol (P < 0.001) than WIS rats did throughout the experiment. Autoradiographic analyses of discrete brain regions indicated that alcohol consumption increased DAT sites in a greater number of brain areas in WKY compared to WIS rats. In WKY rats, the binding of [3H]-GBR12935 to DAT sites was increased in the basolateral, central and lateral nuclei of the amygdala, lateral nucleus of the hypothalamus, olfactory tubercle, caudate-putamen, nucleus accumbens and substantia nigra (P < 0.05) and decreased in the ventromedial nucleus of the hypothalamus and the CA1 region of the hippocampus. In WIS rats, alcohol consumption increased DAT sites in the CA1 region of the hippocampus, basolateral nucleus of the amygdala, ventral tegmental area and substantia nigra, and decreased DAT sites in the lateral and ventromedial hypothalamus and dentate gyrus. These results indicate a strain dependent alteration in DAT sites which may be related to altered dopamine neurotransmission in select brain regions following alcohol consumption.

Effect of sedative and hypnotic doses of propofol on the EEG activity of patients with or without a history of seizure disorders

Propofol is alleged to possess both pro- and anticonvulsant properties, leading to controversy regarding its use in patients with a history of seizures. Since propofol is administered for both sedation and hypnosis, it is important to understand the effects of low (0.5-1.0 mg/kg) and high (2-2.5 mg/kg) doses of propofol on the electroencephalogram (EEG). In this study, the hemodynamic and EEG effects of cumulative doses of propofol from 0.5 to 2.5 mg/kg i.v. were studied in 30 neurosurgical patients with or without a history of seizure disorders. While continuously recording from scalp EEG electrodes (F3, F4, C3, C4, P3, P4, O1, and O2), propofol 0.5 mg/kg was infused intravenously over 20 s. The same dose of propofol was reinjected four times at 2-min intervals, until a total dose of 2.5 mg/kg had been administered. The number and average amplitude of the EEG waves were counted and measured manually, respectively, from 80 to 90 s after beginning the injection of each dose of propofol. After lower propofol doses (0.5-1 mg/kg), the number of beta-waves increased, while alpha- and theta-waves decreased significantly in all patients. However, with larger doses of propofol (total dose of 2-2.5 mg/kg), the number of beta-waves decreased and delta-waves appeared. The amplitudes of all EEG waves increased and were maintained at a higher level after administration of propofol. Spike (or sharp) waves appeared in 33% of the control patients and in 40% of the epileptic group after propofol 0.5 mg/kg and in 73% of the control and 67% of the epileptic patients after the 1.5-mg/kg dose. In the majority of patients, the spike waves disappeared when additional doses of propofol were administered. One patient in the epileptic group had an EEG-recorded and clinical grand mal seizure after propofol 1 mg/kg, but the seizure disappeared after an additional 0.5-mg/kg bolus dose was administered. The propofol-induced EEG changes appeared initially at the frontal and central EEG electrodes and subsequently at the other EEG electrodes. Overall, there were no significant differences in the spectrum of EEG changes between the two patient populations. It is concluded that propofol produces similar dose-dependent effects on EEG activity in patients with or without a history of seizure disorders. While induction of anesthesia with higher doses of propofol (> 1.5 mg/kg) in neurosurgical patients with well controlled seizure disorder is safe, smaller sedative doses should be administered with caution to epileptic patients.

Effects of empagliflozin on progression of chronic kidney disease: a prespecified secondary analysis from the empa-kidney trial

BACKGROUND

Sodium-glucose co-transporter-2 (SGLT2) inhibitors reduce progression of chronic kidney disease and the risk of cardiovascular morbidity and mortality in a wide range of patients. However, their effects on kidney disease progression in some patients with chronic kidney disease are unclear because few clinical kidney outcomes occurred among such patients in the completed trials. In particular, some guidelines stratify their level of recommendation about who should be treated with SGLT2 inhibitors based on diabetes status and albuminuria. We aimed to assess the effects of empagliflozin on progression of chronic kidney disease both overall and among specific types of participants in the EMPA-KIDNEY trial.

METHODS

EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA), and included individuals aged 18 years or older with an estimated glomerular filtration rate (eGFR) of 20 to less than 45 mL/min per 1·73 m2, or with an eGFR of 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher. We explored the effects of 10 mg oral empagliflozin once daily versus placebo on the annualised rate of change in estimated glomerular filtration rate (eGFR slope), a tertiary outcome. We studied the acute slope (from randomisation to 2 months) and chronic slope (from 2 months onwards) separately, using shared parameter models to estimate the latter. Analyses were done in all randomly assigned participants by intention to treat. EMPA-KIDNEY is registered at ClinicalTrials.gov, NCT03594110.

FINDINGS

Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and then followed up for a median of 2·0 years (IQR 1·5-2·4). Prespecified subgroups of eGFR included 2282 (34·5%) participants with an eGFR of less than 30 mL/min per 1·73 m2, 2928 (44·3%) with an eGFR of 30 to less than 45 mL/min per 1·73 m2, and 1399 (21·2%) with an eGFR 45 mL/min per 1·73 m2 or higher. Prespecified subgroups of uACR included 1328 (20·1%) with a uACR of less than 30 mg/g, 1864 (28·2%) with a uACR of 30 to 300 mg/g, and 3417 (51·7%) with a uACR of more than 300 mg/g. Overall, allocation to empagliflozin caused an acute 2·12 mL/min per 1·73 m2 (95% CI 1·83-2·41) reduction in eGFR, equivalent to a 6% (5-6) dip in the first 2 months. After this, it halved the chronic slope from -2·75 to -1·37 mL/min per 1·73 m2 per year (relative difference 50%, 95% CI 42-58). The absolute and relative benefits of empagliflozin on the magnitude of the chronic slope varied significantly depending on diabetes status and baseline levels of eGFR and uACR. In particular, the absolute difference in chronic slopes was lower in patients with lower baseline uACR, but because this group progressed more slowly than those with higher uACR, this translated to a larger relative difference in chronic slopes in this group (86% [36-136] reduction in the chronic slope among those with baseline uACR <30 mg/g compared with a 29% [19-38] reduction for those with baseline uACR ≥2000 mg/g; ptrend<0·0001).

INTERPRETATION

Empagliflozin slowed the rate of progression of chronic kidney disease among all types of participant in the EMPA-KIDNEY trial, including those with little albuminuria. Albuminuria alone should not be used to determine whether to treat with an SGLT2 inhibitor.

FUNDING

Boehringer Ingelheim and Eli Lilly.

Gene rearrangements in hormone receptor negative breast cancers revealed by mate pair sequencing

Background

Chromosomal rearrangements in the form of deletions, insertions, inversions and translocations are frequently observed in breast cancer genomes, and a subset of these rearrangements may play a crucial role in tumorigenesis. To identify novel somatic chromosomal rearrangements, we determined the genome structures of 15 hormone-receptor negative breast tumors by long-insert mate pair massively parallel sequencing.

Results

We identified and validated 40 somatic structural alterations, including the recurring fusion between genes DDX10 and SKA3 and translocations involving the EPHA5 gene. Other rearrangements were found to affect genes in pathways involved in epigenetic regulation, mitosis and signal transduction, underscoring their potential role in breast tumorigenesis. RNA interference-mediated suppression of five candidate genes (DDX10, SKA3, EPHA5, CLTC and TNIK) led to inhibition of breast cancer cell growth. Moreover, downregulation of DDX10 in breast cancer cells lead to an increased frequency of apoptotic nuclear morphology.

Conclusions

Using whole genome mate pair sequencing and RNA interference assays, we have discovered a number of novel gene rearrangements in breast cancer genomes and identified DDX10, SKA3, EPHA5, CLTC and TNIK as potential cancer genes with impact on the growth and proliferation of breast cancer cells.

Identification, isolation, and characterization of a 32-kDa fatty acid-binding protein missing from lymphocytes in humans with Bietti crystalline dystrophy (BCD)

Bietti crystalline dystrophy (BCD) is an autosomal recessive retinal degeneration characterized by intraretinal lipid inclusions with degeneration of the retina and sclerosis of the choroidal vessels, resulting clinically in progressive night blindness and constriction of the visual fields. Characterization of fatty acid metabolism in Bietti crystalline dystrophy suggested that BCD might result from abnormalities in lipid-binding proteins or one or more enzymes active in fatty acid elongation and desaturation. To further investigate the first possibility, the docosahexaenoic acid-binding proteins (DHABPs) of human lymphocytes from patients with Bietti crystalline dystrophy were studied and compared with those of normal controls. For fatty acid-binding protein (FABP) identification, lymphocyte cytosol was first subjected to Lipidex 1000 chromatography. FABPs were then cross-linked with [14C]22:6n-3 and identified by HPLC and SDS-PAGE. Ten major peaks corresponding to calculated molecular weights of 13, 14, 32, 43, 45, 50, 64, 96, 105, and 186 kDa exhibit high-affinity binding of fatty acids. Significantly, peaks corresponding to two fatty acid-binding proteins of 32 and 45 kDa present in age-matched controls are absent from lymphocytes of patients with BCD. The 32-kDa fatty acid-binding protein present in normal individuals but absent from patients with BCD was isolated from cultured control human lymphocytes, its fatty acid-binding properties were characterized, and its amino acid composition was analyzed. It shows specific binding of 3n-3 fatty acids, consistent with the pattern of abnormalities of lipid metabolism demonstrated in patients with BCD. These results suggest that the 32- and 43-kDa FABPs are reasonable candidates for causing BCD.

Developing a CRISPR/Cas9 System for Genome Editing in the Basidiomycetous Yeast Rhodosporidium toruloides

The basidiomycetous yeast Rhodosporidium toruloides (R. toruloides) has been explored as a promising host for the production of lipids and carotenoids. However, the rational manipulation of this yeast remains difficult due to lack of efficient genetic tools. Here, the development of a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated nuclease (Cas9) system for genome editing in R. toruloides is described. First, R. toruloides strains are generated with sufficient production of the Cas9 protein of Staphylococcus aureus origin by integrating a cassette containing a codon-optimized Cas9 gene into the genome. In parallel, two U6 genes are identified, predicting two U6 promoters and confirming better transcription of single-guide RNA (sgRNA) with the U6b promoter. Next, sgRNA cassettes are designed targeting CRTI, CAR2, and CLYBL gene, respectively, transforming into those Cas9-expressed strains, and finding over 60% transformants with successful insertion and deletion (indel) mutations. Furthermore, when the sgRNA cassette includes donor DNA flanked by two homologous arms of the gene CRTI, gene knockout occurs via homologous recombination. Thus, the CRISPR/Cas9 system is now established as a powerful genome-editing tool in R. toruloides, which should facilitate functional genomic study and advanced cell factory development.

APP/PS1 Transgenic Mice Treated with Aluminum: An Update of Alzheimer's Disease Model

There is still no animal model available that can mimic all the cognitive, behavioral, biochemical, and histopathological abnormalities observed in patients with Alzheimer's disease (AD). We undertook to consider the interaction between genetic factors, including amyloid precursor protein (APP) and presenilin-1 (PS1), and environmental factors, such as Aluminum (Al) in determining susceptibility outcomes when studying the pathogenesis of AD. In this article, we provide an AD model in APP/PS1 transgenic mice triggered by Al. The animal model was established via intracerebral ventricular microinjection of aluminum chloride once a day for 5 days in APP/PS1 transgenic mice. Twenty wild type (WT) mice and 20 APP/PS1 transgenic (TG) mice were separately divided into 2 groups (control and Al group), and a stainless steel injector with stopper was used for microinjection into the left-lateral cerebral ventricle of each mouse. The Morris water maze task was used to evaluate behavioral function of learning and memory ability on the 20th day after the last injection. This AD model's brain was analyzed by: (1) amyloid β immunohistochemical staining; (2) Tunnel staining; (3) apoptotic rates; (4) caspase-3 gene expression. Here, decrease of cognitive ability and neural cells loss were shown in APP/PS1 transgenic mice exposed to Al, which were more extensive than those in APP/PS1 TG alone and WT mice exposed to Al alone. These findings indicate that there is a close relationship between over-expression of APP and PS1 genes and Al overload. It is also suggested that APP/PS1 TG mice exposed to Al have potential value for improving AD models.

HOXA13 is associated with unfavorable survival and acts as a novel oncogene in prostate carcinoma

AIM

To investigate the clinical relevance and functional role of HOXA13 in prostate cancer Methods: PCR, western blot and immunohistochemistry were performed to determine the expression. Kaplan-Meier and Cox regression survival analyses investigated the clinical relevance. Cell viability, flow cytometry and transwell assays were used to determine the functional roles.

RESULTS

HOXA13 expression is sharply increased in carcinoma tissues and is significantly associated with poor prognosis of prostate cancer patients. Interestingly, nucleus not cytoplasm HOXA13 expression is associated with unfavorable survival of the patients. Furthermore, nucleus HOXA13 expression represents an unfavorable and independent prognosis factor of histological grade 2 or Gleason grade <8 patients. Functionally, forced expression of HOXA13 obviously promotes tumor cell proliferation, migration and invasion, whereas inhibits tumor cell apoptosis.

CONCLUSION

HOXA13 is an unfavorable prognostic factor and a novel oncogene for prostate cancer.

Evidence for viscoelastic effects in surface capillary waves of molten polymer films

The surface dynamics of supported ultrathin polystyrene films with thickness comparable to the radius of gyration were investigated by surface sensitive x-ray photon correlation spectroscopy. We show for the first time that the conventional model of capillary waves on a viscous liquid has to be modified to include the effects of a shear modulus in order to explain both static and dynamic scattering data from ultrathin molten polymer films.

Noninvasive measurement of protein concentration

At selected magnetic field strengths, protein and water proton spin-lattice relaxation rates are sensitive to the concentration of rotationally immobilized peptide nitrogen because of field dependent heteronuclear cross relaxation coupling between protein proton and nitrogen-14 spins that is carried to the water by proton homonuclear cross-relaxation. Measurement of the water proton spin-lattice relaxation time, or a signal amplitude proportional to it, may provide a noninvasive measure of peptide bond concentration, which provides a direct measure of immobilized protein content in most tissues. The approach using protein gels in two magnetic field strengths is demonstrated. At 66.7 mT; the proton Zeeman energy matches one of the peptide nitrogen transitions dominated by the unaveraged nuclear electric quadrupole interaction; cross-relaxation between the protons and nitrogen-14 is efficient. At 77.5 mT, the proton Zeeman energy is not matched with the nitrogen energy and proton-nitrogen cross-relaxation is not efficient. It is shown that the difference in the water proton spin-lattice relaxation rates on and off the energy level match condition is a linear function of the rotationally immobilized protein concentration.

Consistent striatal damage in rats induced by 3-nitropropionic acid and cultures of arthrinium fungus

Arthrinium fungi were cultivated from the samples of mildewed sugarcane which caused acute encephalopathy and delayed dystonia in children. The Arthrinium cultures (AC) contained 5 mg/ml 3-nitropropionic acid (3-NPA) after being inactivated and concentrated. A neuropathological study was carried out in rats intoxicated with 3-NPA and AC, respectively. Consistent bilateral striatal necrosis was found in rats with both poisonings, and the severity was well correlated with persistent recumbency which was a clinical indicator of the development of morphological brain lesions. A reproducible animal model of striatal damage has been produced in rats by IP injections of 10 mg/kg 3-NPA, 6 times a day, with an interval of 1.5 h for 3-5 days. The clinical and neuropathological manifestations in rats dosed with AC were nearly the same as those dosed with 3-NPA. The striatal lesions induced by 3-NPA and AC in poisoned rats were in accordance with the bilateral lenticular hypodensity found by CT scanning in patients of mildewed sugarcane poisoning with delayed dystonia. This neuropathological evidence supports previous epidemiological and mycological findings which indicate that 3-NPA is the possible pathogen of acute mildewed sugarcane poisoning.

3-Nitropropionic acid produces indirect excitotoxic damage to rat striatum

The mechanism of striatal damage induced by 3-nitropropionic acid (3-NPA) was studied in rats by neuropathological and neurochemical methods. Neuronal shrinkage with astrogliosis was observed in striatum after local injection of 0.5-5 mumol 3-NPA. Decortications involving dorsal and lateral aspects of frontal cortex or both frontal and parietal cortices significantly decreased the severity of striatal injuries induced by 3-NPA. This result suggests that corticostriatal projections play an important role in the development of striatal damage. No significant increase of glutamate and aspartate in striatal dialysates was observed, which indicated that 3-NPA may affect the postsynaptical sites and make the striatal neurons more vulnerable to endogenous levels of glutamate. Both of these findings suggested that 3-NPA produces indirect excitotoxic lesion to striatum. An increase of dopamine found in striatal dialysates may also be related to the occurrence of striatal damage.

Thickness induced structural changes in polystyrene films

Changes to the structure of polystyrene melt films as measured through the spectrum of density fluctuations have been observed as a function of film thickness down to the polymer radius of gyration (Rg). Films thicker than 4Rg show bulklike density fluctuations. Thinner films exhibit a peak in S(q) near q=0 which grows with decreasing thickness. This peak is attributed to a decreased interpenetration of chains resulting in an enhanced compressibility. Measurements were made using small angle x-ray scattering in a standing wave geometry designed to enhance scattering from the interior of the film compared to interface scattering.