D-arabinose acts as antidepressant by activating the ACSS2-PPARγ/TFEB axis and CRTC1 transcription.

CREB-regulated transcription coactivator 1 (CRTC1), a pivotal synaptonuclear messenger, regulates synaptic plasticity and transmission to prevent depression. Despite exhaustive investigations into CRTC1 mRNA reductions in the depressed mice, the regulatory mechanisms governing its transcription remain elusive. Consequently, exploring rapid but non-toxic CRTC1 inducers at the transcriptional level is important for resisting depression. Here, we demonstrate the potential of D-arabinose, a unique monosaccharide prevalent in edible-medicinal plants, to rapidly enter the brain and induce CRTC1 expression, thereby eliciting rapid-acting and persistent antidepressant responses in chronic restrain stress (CRS)-induced depressed mice. Mechanistically, D-arabinose induces the expressions of peroxisome proliferator-activated receptor gamma (PPARγ) and transcription factor EB (TFEB), thereby activating CRTC1 transcription. Notably, we elucidate the pivotal role of the acetyl-CoA synthetase short-chain family member 2 (ACSS2) as an obligatory mediator for PPARγ and TFEB to potentiate CRTC1 transcription. Furthermore, D-arabinose augments ACSS2-dependent CRTC1 transcription by activating AMPK through lysosomal AXIN-LKB1 pathway. Correspondingly, the hippocampal down-regulations of ACSS2, PPARγ or TFEB alone failed to reverse CRTC1 reductions in CRS-exposure mice, ultimately abolishing the anti-depressant efficacy of D-arabinose. In summary, our study unveils a previously unexplored role of D-arabinose in activating the ACSS2-PPARγ/TFEB-CRTC1 axis, presenting it as a promising avenue for the prevention and treatment of depression.

A homogeneous polysaccharide from Lycium barbarum: Structural characterizations, anti-obesity effects and impacts on gut microbiota.

Lycium barbarum polysaccharides (LBPs) are known for their beneficial effects on diabetes, NAFLD and related chronic metabolic diseases induced by high-fat diet (HFD). However, the relevant researches are mainly about the whole crude polysaccharides, the specific active ingredient of LBPs and its bioactivity have been rarely explored. Herein, a homogeneous polysaccharide (LBP-W) was isolated and purified from crude LBPs. Structure characterizations indicated that LBP-W contained a main chain consisting of a repeated unit of →6)-ß-Galp(1 â†’ residues with branches composed of α-Araf, ß-Galp and α-Rhap residues at position C-3. The objective of this study was to evaluate the anti-obesogenic effect of LBP-W and figure out the underlying mechanisms. In vivo efficacy trial illustrated that LBP-W supplements can alleviate HFD-induced mice obesity significantly. Gut microbiota analysis showed that LBP-W not only improved community diversity of intestinal flora, but also regulated their specific genera. Moreover, LBP-W can increase the content of short-chain fatty acids (SCFAs), a metabolite of the intestinal flora. In summary, all these results demonstrated that the homogeneous polysaccharide purified from L. barbarum could be used as a prebiotic agent to improve obesity by modulating the composition of intestinal flora and the metabolism of SCFAs.

Multidirectional insights on polysaccharides from Schinus terebinthifolius and Schinus molle fruits: Physicochemical and functional profiles, in vitro antioxidant, anti-genotoxicity, antidiabetic, and antihemolytic capacities, and in vivo anti-inflammatory and anti-nociceptive properties.

The aim of the current study was to compare crude polysaccharides extracted from Schinus terebinthifolius Raddi (PSTF) and S. molle L. (PSMF) fruits based on their structures, physicochemical characteristics, monosaccharide composition, as well as in vitro and in vivo assays. The extraction yield of PSTF (4.26%) was higher than that of PSMF (3.56%). Remarkable variability was detected in the content of carbohydrates (80.64 ± 0.98%), protein (1.80 ± 0.28%), fat (0.04 ± 0.005%) and ash (6.32 ± 0.26%). FT-IR assay and 1H and 13C NMR spectroscopy revealed that fruits extract showed similar structural characteristics. Thin layer chromatography together with HPLC-RID analysis showed that the monosaccharide composition varied significantly between species. Both contained arabinose (40.55-42.03%) galacturonic acid (31.21-41.15%), and fucose (10.90-17.63%), but PSTF had glucose (9.13%) whereas PSMF had galactose (7.40%). Functional analyses demonstrated that samples exhibited favorable water- and oil-retention capacity, emulsifying properties, and foaming qualities. PSTF exhibited the highest antioxidant effects. Both of them showed a remarkable in vitro antidiabetic effect. PSMF highly mitigated H2O2-induced hemolysis and exhibited ~80% antihemolytic activity. The extracted polysaccharides showed potent inhibitory activity against AAPH-induced plasmid DNA damage. PSTF and PSMF revealed interesting in vivo antinociceptive and anti-inflammatory capacities.

Nonmetabolizable Arabinose Inhibits Vibrio cholerae Growth in M9 Medium with Gluconate as the Sole Carbon Source.

The serogroups O1 and O139 of the marine bacterium Vibrio cholerae are responsible for causing cholera in humans. The pentose sugar arabinose is nonmetabolizable by the pathogen and is present in environmental niches as well as in the human intestine. In this study, arabinose-mediated V. cholerae growth interference was assessed in M9 minimal medium containing gluconate as the sole carbon source in the light of Entner-Doudoroff (ED) pathway, an obligatory metabolic route for gluconate utilization. V. cholerae O1 and O139 strains failed to grow in the presence of ≥ 0.3% arabinose in M9 with 0.2% gluconate, but there was no growth inhibition in the presence of arabinose in M9 with 0.2% glucose. Transcriptional analysis of edd and eda, the genes constituting the ED pathway, showed ~100- and ~17-fold increases, respectively, in M9-gluconate. Minor increases of ~4- and ~2-fold for edd and eda, respectively, were noted in AKI medium supplemented with 0.5% arabinose. The observed arabinose-mediated growth inhibition can contribute toward deepening the understanding of altered phenotypes, if any, via complementation/expression studies in V. cholerae with pBAD vectors and arabinose as an inducer.

Inadequate brain glycogen or sleep increases spreading depression susceptibility.

OBJECTIVE: Glycogen in astrocyte processes contributes to maintenance of low extracellular glutamate and K+ concentrations around excitatory synapses. Sleep deprivation (SD), a common migraine trigger, induces transcriptional changes in astrocytes, reducing glycogen breakdown. We hypothesize that when glycogen utilization cannot match synaptic energy demand, extracellular K+ can rise to levels that activate neuronal pannexin-1 channels and downstream inflammatory pathway, which might be one of the mechanisms initiating migraine headaches. METHODS: We suppressed glycogen breakdown by inhibiting glycogen phosphorylation with 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) and by SD. RESULTS: DAB caused neuronal pannexin-1 large pore opening and activation of the downstream inflammatory pathway as shown by procaspase-1 cleavage and HMGB1 release from neurons. Six-hour SD induced pannexin-1 mRNA. DAB and SD also lowered the cortical spreading depression (CSD) induction threshold, which was reversed by glucose or lactate supplement, suggesting that glycogen-derived energy substrates are needed to prevent CSD generation. Supporting this, knocking down the neuronal lactate transporter MCT2 with an antisense oligonucleotide or inhibiting glucose transport from vessels to astrocytes with intracerebroventricularly delivered phloretin reduced the CSD threshold. In vivo recordings with a K+ -sensitive/selective fluoroprobe, Asante Potassium Green-4, revealed that DAB treatment or SD caused a significant rise in extracellular K+ during whisker stimulation, illustrating the critical role of glycogen in extracellular K+ clearance. INTERPRETATION: Synaptic metabolic stress caused by insufficient glycogen-derived energy substrate supply can activate neuronal pannexin-1 channels as well as lower the CSD threshold. Therefore, conditions that limit energy supply to synapses (eg, SD) may predispose to migraine attacks, as suggested by genetic studies associating glucose or lactate transporter deficiency with migraine. Ann Neurol 2018;83:61-73.

Inhibitory properties of 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) derivatives acting on glycogen metabolising enzymes.

Glycogen synthase (GS) and glycogen phosphorylase (GP) are the key enzymes that control, respectively, the synthesis and degradation of glycogen, a multi-branched glucose polymer that serves as a form of energy storage in bacteria, fungi and animals. An abnormal glycogen metabolism is associated with several human diseases. Thus, GS and GP constitute adequate pharmacological targets to modulate cellular glycogen levels by means of their selective inhibition. The compound 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) is a known potent inhibitor of GP. We studied the inhibitory effect of DAB, its enantiomer LAB, and 29 DAB derivatives on the activity of rat muscle glycogen phosphorylase (RMGP) and E. coli glycogen synthase (EcGS). The isoform 4 of sucrose synthase (SuSy4) from Solanum tuberosum L. was also included in the study for comparative purposes. Although these three enzymes possess highly conserved catalytic site architectures, the DAB derivatives analysed showed extremely diverse inhibitory potential. Subtle changes in the positions of crucial residues in their active sites are sufficient to discriminate among the structural differences of the tested inhibitors. For the two Leloir-type enzymes, EcGS and SuSy4, which use sugar nucleotides as donors, the inhibitory potency of the compounds analysed was synergistically enhanced by more than three orders of magnitude in the presence of ADP and UDP, respectively. Our results are consistent with a model in which these compounds bind to the subsite in the active centre of the enzymes that is normally occupied by the glucosyl residue which is transferred between donor and acceptor substrates. The ability to selectively inhibit the catalytic activity of the key enzymes of the glycogen metabolism may represent a new approach for the treatment of disorders of the glycogen metabolism.

Structural characterization of a broccoli polysaccharide and evaluation of anti-cancer cell proliferation effects.

Broccoli is a widely consumed vegetable with abundant amount of nutrients, which bring numerous beneficial effects on human health. The structural information of water-soluble polysaccharides in broccoli was eludicated for the first time in this work. A purified polysaccharide fraction (BPCa) was obtained by column chromatography. It comprised of arabinose (Ara), galactose (Gal), rhamnose (Rha) with a molar ratio of 5.3:0.8:1.0. Nuclear magnetic resonnance spectra data revealed that α-L-1,5-Araf and α-L-1,3,5-Araf are present in the backbone, while α-L-Araf terminal was attended in side chain. α-L-1,2-Rhap was found to be linked to α-L-1,5-Araf in heteronuclear multiple bond correlation spectra. The presences of ß-D-1,4-Galp and α-D-1,4-GalpA were also detected. Furthermore, BPCa showed significant anti-cancer cell proliferation activities against HepG2, Siha and MDA-MB-231 carcinoma cell lines. The results indicated that BPCa had a good potential to be applied as functional food additives.

Lycium barbarum polysaccharides therapeutically improve hepatic functions in non-alcoholic steatohepatitis rats and cellular steatosis model.

This study aimed to investigate the possible therapeutic effects and active components of Lycium barbarum polysaccharides (LBP) on a high fat diet-induced NASH rat model. We induced NASH in a rat model by voluntary oral feeding with a high-fat diet ad libitum for 8 weeks. After 8 weeks, 1 mg/kg LBP was orally administered for another 4 weeks with a high-fat diet. When compared with NASH rats treated for 12 weeks, therapeutic LBP treatment for 4 weeks during 12 weeks of NASH induction showed ameliorative effects on: (1) increased body and wet liver weights; (2) insulin resistance and glucose metabolic dysfunction; (3) elevated level of serum aminotransferases; (4) fat accumulation in the liver and increased serum free fatty acid (FFA) level; (5) hepatic fibrosis; (6) hepatic oxidative stress; (7) hepatic inflammatory response; and (8) hepatic apoptosis. These improvements were partially through the modulation of transcription factor NF-κB, MAPK pathways and the autophagic process. In a palmitate acid-induced rat hepatocyte steatosis cell-based model, we also demonstrated that l-arabinose and ß-carotene partially accounted for the beneficial effects of LBP on the hepatocytes. In conclusion, LBP possesses a variety of hepato-protective properties which make it a potent supplementary therapeutic agent against NASH in future clinical trials.

Chemical composition and vasodilatation induced by Cuphea carthagenensis preparations.

The aerial parts of Cuphea carthagenensis (Jacq.) J.F. Macbride (Lythraceae) are traditionally employed in Brazil to treat cardiovascular diseases. The aim of this study was to compare preparations of C. carthagenensis aerial parts (aqueous and ethanol extracts, together with derived fractions) with regard to their total phenolic contents and in vitro vasodilating activity. The main flavonoids found in the extracts were isolated and identified as quercetin derivatives. The extracts and fractions showed similar HPLC profiles with the presence of quercetin-5-O-ß-glucopyranoside, quercetin-3-O-α-arabinofuranoside and quercetin-3-sulfate in all of them, but marked differences in the contents of flavonoids, proanthocyanidins, tannis and total phenolics. Excepting the aqueous extract, all assayed preparations elicited vasodilatation on pre-contracted rat aortic rings in the range of pIC(50) 4.53±0.03 to 4.98±0.06. Polynomial regression analysis demonstrated the relationship between vasodilating activity and the contents of flavonoids (r(2)=0.5190), proanthocyanidins (r(2)=0.8016), tannins (r(2)=0.8041) and total phenolics (r(2)=0.6226), suggesting the participation of these compounds in the pharmacological effect and their potential use as chemical markers for the species.

Structural characterisation of the polysaccharides from endemic Mongolian desert plants and their effect on the intestinal absorption of ovalbumin.

Using successive extractions with water and 0.7% aqueous ammonium oxalate, pectic polysaccharides were isolated from the following plants growing in the arid climate of Mongolia (Gobi): saxaul Haloxylon ammodendron Maxim., rhubarb Rheum nanum Sievers, Nitraria sibirica Pall., Peganum harmala L. and almond Amygdalus mongolica Maxim. The data obtained exhibited the primary synthesis of the cell wall pectic polysaccharides but not the middle lamellae water-soluble pectins in plants growing in the dry climatic zone. Both α-(1→4)-D-galacturonan and α-(1→4)-D-galacturonan, which was substituted with methyl groups, were found to be backbone of pectins. The L-arabinofuranose residues were identified as the main components of ramified regions. The pectins from almond differed from other pectins due to a high arabinose content. The data from NMR spectroscopy and methylation analyses demonstrated that pectic polysaccharides from almond included terminal, (1→5)-, (1→3)-linked and 3,5-substituted L-arabinofuranose residues and a small terminal D-galactopyranose and 2,5- and 2,3,5-substituted L-arabinofuranose residue content. The pectic polysaccharides were found to decrease the absorption of ovalbumin (OVA) in the blood from the gut lumen. The serum OVA level was lower in mice fed with OVA mixed with the pectins compared with the control group, which was administered OVA alone.

Inhibition of inducible nitric oxide synthase and cyclooxygenase-2 expression by phenolic compounds from roots of Rhododendron mucronulatum.

The roots of Rhododendron mucronulatum Turzaninov have been used in Oriental traditional medicine for the treatment of dysuria, fever, increase of digestive activity and tonics in China and Korea. Activity guided isolation of the roots of Rhododendron mucronulatum Turzaninov has led to the isolation of three flavonoids, one flavan 3-ol and one proanthocyanidin. Chemical investigation of the 80% Me2 CO extract from the roots of Rhododendron mucronulatum led to the isolation and identification of five compounds: taxifolin (1), taxifolin 3-O-ß-D-glucopyranoside (2), quercetin 3-O-α-L-arabinofuranoside (3), (-)-epicatechin (4), procyanidin B-3 (5). To investigate the antioxidative and antiinflammatory effects of these compounds, their 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities and the protein levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-stimulated HaCaT cells were also quantified by western blotting and their end products, nitric oxide (NO) and prostaglandin E2 (PGE2 ), respectively. Compounds (1-5) showed potent DPPH radical scavenging compared with positive controls (L-ascorbic acid). Also, compounds 1 and 2 dose-dependently inhibited the expressions of inflammatory mediators, NO and PGE2 , suggesting they are promising candidates as antiinflammatory agents.

Inhibition by natural dietary substances of gastrointestinal absorption of starch and sucrose in rats and pigs: 1. Acute studies.

Rapid gastrointestinal absorption of refined carbohydrates (CHO) is linked to perturbed glucose-insulin metabolism that is, in turn, associated with many chronic health disorders. We assessed the ability of various natural substances, commonly referred to as "CHO blockers," to influence starch and sucrose absorption in vivo in ninety-six rats and two pigs. These natural enzyme inhibitors of amylase/sucrase reportedly lessen breakdown of starches and sucrose in the gastrointestinal tract, limiting their absorption. To estimate absorption, groups of nine SD rats were gavaged with water or water plus rice starch and/or sucrose; and circulating glucose was measured at timed intervals thereafter. For each variation in the protocol a total of at least nine different rats were studied with an equal number of internal controls on three different occasions. The pigs rapidly drank CHO and inhibitors in their drinking water. In rats, glucose elevations above baseline over four hours following rice starch challenge as estimated by area-under-curve (AUC) were 40%, 27%, and 85% of their internal control after ingesting bean extract, hibiscus extract, and l-arabinose respectively in addition to the rice starch. The former two were significantly different from control. L-Arabinose virtually eliminated the rising circulating glucose levels after sucrose challenge, whereas hibiscus and bean extracts were associated with lesser decreases than l-arabinose that were still significantly lower than control. The glucose elevations above baseline over four hours in rats receiving sucrose (AUC) were 51%, 43% and 2% of control for bean extract, hibiscus extract, and L-arabinose, respectively. Evidence for dose-response of bean and hibiscus extracts is reported. Giving the natural substances minus CHO challenge caused no significant changes in circulating glucose concentrations, indicating no major effects on overall metabolism. A formula combining these natural products significantly decreased both starch and sucrose absorption, even when the CHO were given simultaneously. These results support the hypothesis that the enzyme inhibitors examined here at reasonable doses can safely lower the glycemic loads starch and sucrose.

Inhibition by natural dietary substances of gastrointestinal absorption of starch and sucrose in rats 2. Subchronic studies.

Acute oral consumption of various natural inhibitors of amylase (bean and hibiscus extracts) and sucrase (L-arabinose) reduce absorption of starch and sucrose respectively in rats and pigs measured by lessened appearance of circulating glucose levels. The present subchronic study was designed to determine whether these selected inhibitors of gastrointestinal starch and sucrose absorption (so-called "carb blockers") remain effective with continued use and to assess their metabolic influences after prolonged intake. Sprague-Dawley rats were gavaged twice daily over nine weeks with either water or an equal volume of water containing a formula that included bean and hibiscus extracts and L-arabinose. To estimate CHO absorption, control and treated Sprague-Dawley rats were gavaged with either water alone or an equal volume of water containing glucose, rice starch, sucrose, or combined rice starch and sucrose. Circulating glucose was measured at timed intervals over four hours. The ability to decrease starch and sucrose absorption use. No toxic effects (hepatic, renal, hematologic) were evident. Blood chemistries revealed significantly lower circulating glucose levels and a trend toward decreased HbA1C in the nondiabetic rats receiving the natural formulation compared to control. Subchronic administration of enzyme inhibitors was also associated with many metabolic changes including lowered systolic blood pressure and altered fluid-electrolyte balance. We postulate that proper intake of natural amylase and sucrase inhibitors may be useful in the prevention and treatment of many chronic disorders associated with perturbations in glucose-insulin homeostasis secondary to the rapid absorption of refined CHO.

Weakly antimalarial flavonol arabinofuranosides from Calycolpus warszewiczianus.

Three new flavonol arabinosides (2-4) were isolated from the young leaves of Calycolpus warszewiczianus. The structures were determined as myricetin-3-O-alpha-L-3' '-acetylarabinofuranoside (2), myricetin-3-O-alpha-L-3' ',5' '-diacetylarabinofuranoside (3), and 5-galloylquercetin-3-O-alpha-L-arabinofuranoside (4). Molecular structures were elucidated using NMR spectroscopy in combination with IR and MS data. Two known compounds, myricetin-3-O-alpha-L-arabinofuranoside (1) and (-)-epi-catechin (5), were also isolated. The compounds were tested in vitro against a chloroquine-resistant strain of Plasmodium falciparum, Leishmania mexicana, and Trypanosoma cruzi parasites. Compound 4 demonstrated weak activity against a chloroquine-resistant strain of P. falciparum (14.5 microM), whereas none of the compounds demonstrated activity against L. mexicana and T. cruzi at the concentrations of 40 and 50 microg/mL, respectively, and no cytotoxicity was detected against mammalian cells below 100 microg/mL.

ent-rosane and labdane diterpenoids from Sagittaria sagittifolia and their antibacterial activity against three oral pathogens.

Seven new ent-rosane diterpenoids, sagittines A-G (1-7), together with one new labdane diterpene, 13-epi-manoyl oxide-19-O-alpha-l-2',5'-diacetoxyarabinofuranoside (8), were isolated from the whole plant of Sagittaria sagittifolia. The structures and relative configurations of 1-8 were characterized using spectroscopic means, chemical methods, and X-ray crystallography. Compounds 1-4 exhibited antibacterial activity against the oral pathogens Streptococcus mutans ATCC 25175 and Actinomyces naeslundiis ATCC 12104, with MIC values between 62.5 and 125 microg/mL. Compound 5 was active against only A. naeslundiis ATCC 12104, with an MIC value of 62.5 microg/mL.

Mulberry latex rich in antidiabetic sugar-mimic alkaloids forces dieting on caterpillars.

Since ancient times, mulberry leaves (Morus spp.) have been used to rear the silkworm Bombyx mori. Because the silkworm grows well on mulberry leaves, the toxicities and defensive activities of these leaves against herbivorous insects have been overlooked. Here we show that mulberry leaves are highly toxic to caterpillars other than the silkworm B. mori, because of the ingredients of the latex, a milky sap exuded from mulberry leaf veins. The toxicity of mulberry leaves was lost when the latex was eliminated from the leaves, and artificial diets containing latex showed toxicity. Mulberry latex contained very high concentrations of alkaloidal sugar-mimic glycosidase inhibitors reported to have antidiabetic activities, such as 1,4-dideoxy-1,4-imino-D-arabinitol, 1-deoxynojirimycin, and 1,4-dideoxy-1,4-imino-D-ribitol. The overall concentrations of these inhibitors in latex reached 1.5-2.5% (8-18% dry weight) in several mulberry varieties, which were approximately 100 times the concentrations previously reported from whole mulberry leaves. These sugar-mimic alkaloids were toxic to caterpillars but not to the silkworm B. mori, indicating that the silkworm can circumvent the mulberry tree's defense. Our results suggest that latex ingredients play key roles in defense of this tree and of other plants against insect herbivory, and they imply that plant latexes are treasuries of bioactive substances useful as medicines and pesticides.

Regulation of endopolygalacturonase gene expression in Botrytis cinerea by galacturonic acid, ambient pH and carbon catabolite repression.

The phytopathogenic fungus Botrytis cinerea produces a set of endopolygalacturonases (endoPGs) which are involved in the enzymatic degradation of pectin in plant cell walls. The endoPG-encoding genes of B. cinerea are differentially expressed when the fungus is grown in liquid culture on different carbon sources. A basic constitutive expression level was observed for two genes, Bcpg1 and Bcpg2, which encode basic isozymes. Galacturonic acid was shown to induce the expression of Bcpg4 and Bcpg6. Low pH of the culture medium resulted in induced expression of the Bcpg3 gene. Expression of the Bcpg5 gene was inducible; however the inducing factors could not be identified. Finally, galacturonic acid-induced expression of the Bcpg4 gene was repressed by the presence of more-favourable carbon sources, such as glucose.

Scanning and transmission electron microscopic studies of microvascular pathology in the osmotically impaired blood-brain barrier.

The present investigation focused on the structural events occurring in endothelial cells lining the lumina of brain microvessels in rats subjected to a single intracarotid injection of hypertonic 1.8 M L (+) arabinose solution with or without intravenous injection of horseradish peroxidase. Blood vessels from cerebral cortex and thalamus were evaluated by transmission and scanning electron microscopy. After short-term exposure (10-12 min) there was widespread flooding of peroxidase into the brain neuropil of the ipsilateral hemisphere. Peroxidase tracer was frequently observed within vesiculo-tubular profiles, and occasionally within widened interendothelial junctional clefts. Partially fragmented, necrotic endothelial cells appeared to be in the process of desquamation. Individual endothelial cells appeared to be shrunken with widened interendothelial spaces. Some healthy endothelial cells appeared to be involved in repair processes, manifested by the extension of thin cellular processes towards the area of vessel injury. Other pathological alterations included a conspicuous increase in the number of endothelial cell microvilli, large crater-like invaginations of the endothelial plasma membranes and muscular blood vessels in the process of spasm. We also observed a platelet reaction with or without endothelial cell necrosis and attached microthrombi in some arterial segments.

Mutagenesis by 9-aminoacridine in Salmonella typhimurium: inhibition by glucose and other PTS class A carbon sources.

Reversion of the hisC3076 frameshift marker of Salmonella typhimurium has been measured following treatment of cells in growth and non-growth media with 9-aminoacridine (9AA). By varying the carbon source present in a defined medium, it has been shown that mutagenesis is reduced close to the spontaneous level in the presence of glucose whilst significant reductions are also observed with glucosamine, mannose, mannitol, fructose or glucose 6-phosphate. Intermediate mutant yields are observed when lactic acid or glycerol are present, whereas any one of a further group of carbon sources (gluconate, arabinose, ribose, succinate or casein hydrolysate) permit relatively large numbers of mutants to be recovered. Interestingly, when any one of these "high yield" carbon sources is supplemented with glucose the strong inhibitory effect characteristic of glucose is again observed. On the basis of these results, it can be concluded that inhibition of 9AA-induced reversion by a carbon source is not an exclusive property of glucose, although when more than one carbon source is present the inhibitory effect of glucose predominates. Possible explanations for these findings include the active exclusion of 9AA from cells as a direct consequence of glucose transport across the cell membrane. To address this possibility, cells were pre-grown in verapamil, a calcium channel antagonist which is known to increase the mutagenicity of various 9-anilinoacridine derivatives in S. typhimurium. We found that glucose inhibition of 9AA-induced mutagenesis was not relaxed to any significant extent following treatment with verapamil. In a further experiment, two glucose analogues (2'-deoxyglucose and methyl-D-glucoside) known to be actively transported into the cell but not metabolised past the first phosphorylation step were used. These analogues inhibit the transport into the cell of several types of molecules, but since they do not significantly depress 9AA mutagenesis it seems unlikely that blockage of 9AA transport across the cell membrane can be invoked to explain the inhibitory effect of glucose on 9AA mutagenesis. An alternative explanation based on glucose-mediated repression of an error-prone, mutation-generating, DNA-repair process is presented.

Diffusion into rat brain of contrast and shift reagents for magnetic resonance imaging and spectroscopy.

A sensitive radiotracer technique was used to measure transfer constants (Kis) for blood to brain diffusion of the MR contrast reagent gadolinium diethylenetriaminepentaacetate (GdDTPA2-) and the MR shift reagent dysprosium triethylenetetraminehexaacetate (DyTTHA3-) across the normal and the ischemically injured blood-brain barrier (BBB) of rats. In rats with a normal BBB mean Kis (nL/g/s) for these reagents ranged from 0.3 to 1.4 across eight brain regions and were significantly lower in each region than Kis for sucrose (1.5-3.2), a substance known to be a poor permeant of the intact BBB. Kis measured 6 h after a 10 min period of normothermic forebrain ischemia were increased to 4.0-6.2 (reagents) and 6.6-7.5 (sucrose) in two brain regions, striatum and hippocampus, known to be especially vulnerable to ischemic injury. Measurements of BBB permeability to DyTTHA3- after osmotic opening of the barrier with hypertonic arabinose gave Kis of 25-30 in forebrain regions. Estimates of reagent concentrations in brain interstitial fluid 30 min after dosing the animals indicated that both an extremely high dose of DyTTHA3- and severe disruption of the BBB would be required to shift the resonance frequency of extracellular Na+ appreciably. With the moderate degrees of BBB injury produced by short-term ischemia, a dose of GdDTPA2- about 25 times the usual clinical dose of 0.1 mmol/kg would be required to quantify the injury by dynamic MRI.