Running wheel exercise enhances recovery from nigrostriatal dopamine injury without inducing neuroprotection

Forced use of the forelimb contralateral to a unilateral injection of the dopaminergic neurotoxin 6-hydroxydopamine can promote recovery of motor function in that limb and can significantly decrease damage to dopamine terminals. The present study was conducted to determine (1) whether a form of voluntary exercise, wheel running, would improve motor performance in rats with such lesions, and (2) whether any beneficial effects of wheel running are attributable to ameliorating the dopaminergic damage. In experiment 1, rats were allowed to run in exercise wheels or kept in home cages for 2 1/2 weeks, then given stereotaxic infusions of 6-hydroxydopamine into the left striatum. The rats were replaced into their original environments (wheels or home cages) for four additional weeks, and asymmetries in forelimb use were quantified at 3, 10, 17, and 24 days postoperatively. After killing, dopaminergic damage was assessed by both quantifying 3 beta-(4-iodophenyl)tropan-2 beta-carboxylic acid methyl ester ([(125)I]RTI-55) binding to striatal dopamine transporters and counting tyrosine hydroxylase-positive cells in the substantia nigra. Exercised 6-hydroxydopamine-infused rats showed improved motor outcomes relative to sedentary lesioned controls, effects that were most apparent at postoperative days 17 and 24. Despite this behavioral improvement, 6-hydroxydopamine-induced loss of striatal dopamine transporters and tyrosine hydroxylase-positive nigral cells in exercised and sedentary groups did not differ. Since prior studies suggested that forced limb use improves motor performance by sparing nigrostriatal dopaminergic neurons from 6-hydroxydopamine damage, experiment 2 used a combined regimen of forced plus voluntary wheel running. Again, we found that the motor performance of exercised rats improved more rapidly than that of sedentary controls, but that there were no differences between these groups in the damage produced by 6-hydroxydopamine. It appears that voluntary exercise can facilitate recovery from partial nigrostriatal injury, but it does so without evident sparing of dopamine nerve terminals.

Hyperperfusion on perfusion computed tomography following revascularization for acute stroke

PURPOSE

To describe the findings of hyperperfusion on perfusion computed tomography (CT) in four patients following revascularization for acute stroke.

MATERIAL AND METHODS

In 2002-2003, among a series of 6 patients presenting with an acute stroke and treated with intra-arterial thrombolysis, we observed the presence of hyperperfusion in 3 patients on the follow-up CT perfusion. We included an additional patient who was treated with intravenous thrombolysis and who had hyperperfusion on the follow-up CT perfusion. We retrospectively analyzed their CT perfusion maps. Cerebral blood volume (CBV) and cerebral blood flow (CBF) maps were compared between the affected territory and the normal contralateral hemisphere.

RESULTS

In the four patients, the mean CBV and CBF were 3.6 +/- 2.0 ml/100 g and 39 +/- 25 ml/100 g/min in the affected territory compared to the normal side (mean CBV = 2.7 +/- 2.1 ml/100 g, mean CBF = 27 +/- 23 ml/100 g/min). There was no intracranial hemorrhage in the hyperperfused territories. At follow-up CT, some hyperperfused brain areas progressed to infarction, while others retained normal white to gray matter differentiation.

CONCLUSION

CT perfusion can demonstrate hyperperfusion, which can be seen in an ischemic brain territory following recanalization.

Mapping quantitative trait loci associated with leaf and stem pubescence in cotton

Leaf pubescence in cotton have a potential for insect pest management. Varying degrees of leaf trichome density in Gossypium species and cultivars have been associated to a series of five genes, referred to as t(1)-t(5). We used two segregating interspecific G. hirsutum x G. barbadense backcross populations developed in our laboratory to assess qualitatively and quantitatively leaf and stem pubescence. QTL analyses were performed using simple and composite interval mapping. Based on both types of measurements and under both types of QTL analyses, nine QTLs met permutation-based thresholds. The nine QTLs mapped to four different chromosome regions. Highest LOD values corresponded to the QTLs detected on c6 (four colocalized QTLs) and on D03 (two QTLs) for which the higher pubescence in the progeny derived from the pubescent G. hirsutum parent alleles. Conversely, on c17 (one QTL) and A01 (two QTLs), the G. hirsutum parental alleles affected negatively pubescence. These results combined with another published study confirm (1) the location in a center region of chromosome 6 of the t(1) locus as a major locus/gene determining leaf pubescence, and (2) additional genes located on seven additional chromosomes have been shown to impart trichome density either positively or negatively. The existence of a high density of PCR-based loci in most of the regions identified as harboring leaf pubescence QTLs, particularly that on chromosome 6, will facilitate future efforts for map-based cloning.

Local action of estrogen and thyroid hormone on vasoactive intestinal peptide (VIP) and galanin gene expression in the rat anterior pituitary

Neuropeptides act within the pituitary as autocrine or paracrine factors, modulating the synthesis and release of primary pituitary hormones, and possibly regulating cell proliferation and/or plasticity. Manipulation of the endocrine status of rats produces dramatic long-term changes in the pituitary expression of several peptides, including the neuropeptides galanin and vasoactive intestinal peptide (VIP). Whether or not these changes are caused indirectly by hypothalamic factors, or by hormone actions directly in the pituitary, has been only partially addressed. To determine if estrogen or thyroid hormone can act directly within the pituitary to regulate VIP and galanin gene expression, cultured female rat pituitary cells were treated with 10 nM 1,17 beta-estradiol (E2) or triiodothyronine (T(3)). E2 treatment for three days resulted in an approximate 5-fold and 7-fold increase in VIP and galanin mRNA, respectively. In contrast, T(3) treatment reduced the mRNA levels of these neuropeptides to approximately 40% and 30% of control values. A time course study indicated that the actions of estrogen on VIP and galanin mRNA, and of thyroid hormone on VIP mRNA were readily apparent after 24h. The rat pituitary tumor cell line RC-4B/C was found to express easily detectable levels of galanin but not VIP mRNA. Galanin gene expression in these cells was moderately increased by E2 and decreased by T(3). Transfection of a series of luciferase plasmids containing 5 kb to 131 bp of the bovine galanin promoter fused to luciferase revealed cell-type specific enhancer sequences located between -452 and -131 bp of the galanin gene transcription start site. However, transfected plasmids were minimally responsive to E2 and T(3) treatment. Overall the results suggest that E2 and T(3) exert significant local actions in the pituitary on VIP and galanin gene expression. The bovine galanin gene fragment used in these studies contains a potential pituitary cell-type specific enhancer, but appears to lack strong E2-and T(3)-responsive sequences.

The effect of sewage sludge composting on the quantitative state of some groups of bacteria and fungi

Analysis of the quantitative state of disease causing bacteria and of other microbic groups were done on the sewage sludge from a sewage treatment plant. The results of the analysis include the ammonifying bacteria, nitrifying and denitrifying bacteria. The general quantity of bacteria and fungi in a secondary dehydrated sludge, fermented secondary dehydrated sludge, and in composted secondary dehydrated sludge was deterinated. Composts were prepared from dehydrated secondary sludge with the addition of sawdust. Microbiological analysis of sewage sludge showed, that the quantities of the fecal coli bacteria were 6500; 220 and 150 cells per cm3 of the secondary dehydrated sludge, fermented secondary dehydrated sludge and composted dehydrated secondary sludge, respectively. The numbers of Salmonella were respectively 67.80; 6.48 and 6.60 cells per cm3. The general numbers of bacteria were 2.98 x 10(7); 2.79 x 10(7); 2.15 x 10(7) cells per cm3 of sludge. The cell numbers of fungi were: 6.20x 10(2); 19.60 x 10(2); 7.80 x 10(2) per cm3 of sludge. In the three types of sludge, the results show great numbers of the ammonifying, nitrifying and denitrifying bacteria. Of the analysed groups of bacteria, the highest numbers of cells were found for general bacteria; ammonifying and nitrifying bacteria were next in abundance; still fewer were the denitrifying bacteria. Fungi and pathogenic bacteria were the least numerous.

Pharmaceutical sector in transition--a cross sectional study in Vietnam

Increasing efforts are being made to improve pharmaceutical sector performance in low- and middle-income countries. An essential tool for such work is an objective and standard method of assessment which can be used to promote evidenced based National Drug Policy development and implementation. The average drug expenditure per capita has steadily increased in Vietnam and at the time of this study a National Drug Policy was being developed. This study assessed the Vietnamese pharmaceutical sector 1991-1994, focusing on the standard of the drug quality control system, availability of drugs and rational use of essential drugs in the private and public sectors by means of standardised indicators. The results from this study show that the quality control system is impaired and does not have capacity to quality control all drugs on the market. The availability of essential drugs is good whereas essential drugs are poorly prescribed, injections common and there is a high average number of drugs per prescription, both in the public and private sectors. Violations are common and enforcement of regulations weak. On top of this there is an active commercial advertising and marketing of drugs. These findings identify priorities for action to improve the present situation where the development and implementation of the Vietnamese National Drug Policy will be of major importance.

Regulation of the diabetes-associated autoantigen IA-2 in INS-1 pancreatic beta-cells

IA-2, a member of the protein tyrosine phosphatase family, represents a major target autoantigen in type 1 diabetes. To study the regulation of IA-2 gene expression, we used INS-1 insulinoma cells to analyze beta-cell signal transduction pathways as well as the effect of metabolic and hormonal factors involved in the regulation of the insulin secretory pathway. Quantitative competitive reverse transcriptase-polymerase chain reaction revealed that an increase of cellular cAMP mediated by forskolin (10 micromol/l, 24 h) or 3-isobutyl-1-methylxanthine (100 micromol/l, 24 h) induced maximal stimulation of IA-2 mRNA levels (451 +/- 85 and 338 +/- 86% compared with basal conditions; P < 0.001). In contrast, activation of protein kinase C (PKC) by short-term treatment with phorbol 12-myristate 13-acetate (PMA) (1 micromol/l, 6 h) did not alter IA-2 expression, whereas depletion of PKC by prolonged culturing (24 h) exerted a significant inhibition (57 +/- 24%; P < 0.05). cAMP-dependent upregulation was confirmed by the findings that glucagon (10 micromol/l, 24-48 h) increased levels of IA-2 mRNA (190 +/- 35%; P < 0.05), whereas short-term incubation with high glucose concentration showed no effect. However, prolonged incubation in high glucose (21 mmol/l) induced a time- and dose-dependent increase of IA-2 mRNA expression, reaching maximal values after 144 h (285 +/- 68%; P < 0.05). These studies demonstrate that stimuli of insulin secretion that operate by activation of adenylate cyclase generating cAMP significantly increase IA-2 gene expression. In contrast, activation of PKC by high glucose concentration or PMA exerted no effect, suggesting that IA-2 gene expression is not simply coupled to insulin secretion, but may be involved in the fine regulation of beta-cell function. These findings may be important to clarify the function of IA-2 in beta-cells and elucidate mechanisms involved in the induction of autoimmunity to IA-2.

Identification of a nucleic acid binding domain in eukaryotic initiation factor eIFiso4G from wheat

Higher plants have two complexes that bind the m7G-cap structure of mRNA and mediate interactions between mRNA and ribosomal subunits, designated eIF4F and eIFiso4F. Both complexes contain a small subunit that binds the 5'-cap structure of mRNA, and a large subunit, eIF4G or eIFiso4G, that binds other translation factors and RNA. Sequence-specific proteases were used to cleave native cap-binding complexes into structural domains, which were purified by affinity chromatography. We show here that eIFiso4G contains a central protease-resistant domain that binds specifically to nucleic acids. This domain spans Gln170 to Glu443 and includes four of the six homology blocks shared by eIFiso4G and eIF4G. A slightly shorter overlapping sequence, from Gly202 to Lys445, had no nucleic acid binding activity, indicating that the N-terminal end of the nucleic acid binding site lies within Gln170 to Arg201. The binding of the central domain and native eIFiso4F to RNA homopolymers and double- and single-stranded DNAs was studied. Both molecules had highest affinity for poly(G) and recognized single- and double-stranded sequences.

Synthesis of 1-[11C]methylpiperidin-4-yl propionate ([11C]PMP) for in vivo measurements of acetylcholinesterase activity

Synthesis of 1-[11C]methylpiperidin-4-yl propionate ([11C]PMP), an in vivo substrate for acetylcholinesterase, is reported. An improved preparation of 4-piperidinyl propionate (PHP), the immediate precursor for radiolabeling, was accomplished in three steps from 4-hydroxypiperidine by (a) protection of the amine as the benzyl carbamate, (b) acylation with propionyl chloride, and (c) deprotection of the carbamate by catalytic hydrogenation. The final product was obtained in an overall 82% yield. Reaction of the free base form of PHP with [11C]methyl trifluoromethanesulfonate at room temperature in N,N-dimethylformamide, followed by high performance liquid chromatography (HPLC) purification, provided [11C]PMP in 57% radiochemical yield, > 99% radiochemical purity, and > 1500 Ci/mmol at the end of synthesis. The total synthesis time from end-of-bombardment was 35 min. [11C]PMP can thus be reliably prepared for routine clinical studies of acetylcholinesterase in human brain using positron emission tomography.

Syntheses of carbon-11 labeled piperidine esters as potential in vivo substrates for acetylcholinesterase

A series of carbon-11 labeled N-methylpiperidinyl esters were prepared as potential in vivo substrates for acetylcholinesterase (AChE). Target compounds were designed based on the structure of N-[11C]methylpiperidin-4-yl propionate, an ester currently used to measure AChE enzymatic activity in the human brain, to examine the structure-activity relationship for in vivo enzymatic hydrolysis. Changes in steric bulk and in the ester order ("reverse" esters) were made. Addition of methyl groups was made to both the acid side chain (synthesis of N-[11C]methylmethylpiperidin-4-yl isobutyrate) and to the piperidine ring (syntheses of N-[11C]methyl-4-methylpiperidin-4-yl propionate, N-[11C]methyl-4-methylpiperidin-4-yl acetate, and N-[11C]methyl-3-methylpiperidin-4-yl propionate). Alterations of the order of the ester heteroatoms was accomplished through syntheses of the N-[11C]methyl-2,3- and 4-piperidinecarboxylic acid ethyl esters. Finally, an additional piperidine-based ester (N-[11C]methylpiperidin-2-yl)methyl propionate was also prepared. All carbon-11-labeled esters were prepared by N-[11C]methylation reactions, using the desmethyl precursors and no-carrier-added [11C]methyltriflate, and were obtained in decay-corrected yields (not optimized) of 10-40% and high specific activities.

N-[11C]methylpiperidine esters as acetylcholinesterase substrates: an in vivo structure-reactivity study

A series of simple esters incorporating the N-[11C]methylpiperidine structure were examined as in vivo substrates for acetylcholinesterase in mouse brain. 4-N-[11C]Methylpiperidinyl esters, including the acetate, propionate and isobutyrate esters, are good in vivo substrates for mammalian cholinesterases. Introduction of a methyl group at the 4-position of the 4-piperidinol esters, to form the ester of a teritary alcohol, effectively blocks enzymatic action. Methylation of 4-N-[11C]methylpiperidinyl propionate at the 3-position gives a derivative with increased in vivo reactivity toward acetylcholinesterase. Esters of piperidinecarboxylic acids (nipecotic, isonipecotic and pipecolinic acid ethyl esters) are not hydrolyzed by acetylcholinesterase in vivo, nor do they act as in vivo inhibitors of the enzyme. This study has identified simple methods to both increase and decrease the in vivo reactivity of piperidinyl esters toward acetylcholinesterase.

Neural tube expression of pituitary adenylate cyclase-activating peptide (PACAP) and receptor: potential role in patterning and neurogenesis

Neural tube patterning in vertebrates is controlled in part by locally secreted factors that act in a paracrine manner on nearby cells to regulate proliferation and gene expression. We show here by in situ hybridization that genes for the neuropeptide pituitary adenylate cyclase-activating peptide (PACAP) and one of its high-affinity receptors (PAC1) are widely expressed in the mouse neural tube on embryonic day (E) 10.5. Transcripts for the ligand are present in differentiating neurons in much of the neural tube, whereas the receptor gene is expressed in the underlying ventricular zone, most prominently in the alar region and floor plate. PACAP potently increased cAMP levels more than 20-fold in cultured E10.5 hindbrain neuroepithelial cells, suggesting that PACAP activates protein kinase A (PKA) in the neural tube and might act in the process of patterning. Consistent with this possibility, PACAP down-regulated expression of the sonic hedgehog- and PKA-dependent target gene gli-1 in cultured neuroepithelial cells, concomitant with a decrease in DNA synthesis. PACAP is thus an early inducer of cAMP levels in the embryo and may act in the neural tube during patterning to control cell proliferation and gene expression.

Purification and characterization of a dextranase from Sporothrix schenckii

A dextranase (EC 3.2.1.11) was purified and characterized from the IP-29 strain of Sporothrix schenckii, a dimorphic pathogenic fungus. Growing cells secreted the enzyme into a standard culture medium (20 degrees C) that supports the mycelial phase. Soluble bacterial dextrans substituted for glucose as substrate with a small decrease in cellular yield but a tenfold increase in the production of dextranase. This enzyme is a monomeric protein with a molecular mass of 79 kDa, a pH optimum of 5.0, and an action pattern against a soluble 170-kDa bacterial dextran that leads to a final mixture of glucose (38%), isomaltose (38%), and branched oligosaccharides (24%). In the presence of 200 mM sodium acetate buffer (pH 5.0), the Km for soluble dextran was 0.067 +/- 0.003% (w/v). Salts of Hg2+, (UO2)2+, Pb2+, Cu2+, and Zn2+ inhibited by affecting both Vmax and Km. The enzyme was most stable between pH values of 4.50 and 4.75, where the half-life at 55 degrees C was 18 min and the energy of activation for heat denaturation was 99 kcal/mol. S. schenckii dextranase catalyzed the degradation of cross-linked dextran chains in Sephadex G-50 to G-200, and the latter was a good substrate for cell growth at 20 degrees C. Highly cross-linked grades (i.e., G-10 and G-25) were refractory to hydrolysis. Most strains of S. schenckii from Europe and North America tested positive for dextranase when grown at 20 degrees C. All of these isolates grew on glucose at 35 degrees C, a condition that is typically associated with the yeast phase, but they did not express dextranase and were incapable of using dextran as a carbon source at the higher temperature.