bluuebunny/crossref_metadata_2025 huggingface dataset:
Longterm survival of transplanted human corneal epithelial cells and corneal stem cells
Authors: Egarth Maria , Hellkvist Josefine , Claesson Margareta , Hanson Charles , Stenevi Ulf
Published: September 2005

Purpose:  To investigate the survival of donor‐derived epithelial cells in conventional penetrating keratoplasty (PKP) and in homologous penetrating central limbal keratoplasty (HPCLK).

Methods and Patients:  Epithelial cells from 26 eyes of 26 patients were analysed. All cases were sex‐mismatched (i.e. the transplant and patient were of different genders). At suture removal more than 1 year post surgery, epithelial cells were obtained by gently wiping the removed sutures on glass slides. The cell samples were analysed using fluorescent in situ hybridization (FISH) of the sex chromosomes. This technique makes it possible to allocate the origin of each cell nucleus to either the donor or the recipient.

Results:  All 19 conventional PKPs were clear and seven had donor‐derived epithelial cells at suture removal. Five of the seven HPCLK grafts were clear at the time of investigation (365–1355 days post surgery), and donor‐derived epithelial cells were found in two grafts.

Conclusion:  Harvesting cells from removed sutures in combination with FISH enables the clinical study of cell survival in corneal transplants without jeopardizing functioning grafts. From the limited sample investigated, the following tentative conclusions can be made. Donor‐derived epithelial cells can remain in conventional PKP for over 1 year. In combined stem cell and corneal grafts (HPCLK), donor‐derived epithelial cells may also be retrieved at 1 year or beyond following surgery but the correlation between their presence and a remaining clear graft is uncertain.
Manganese (IV) oxide‐catalyzed electrophilic diamination of electron‐deficient alkenes provides an easy synthesis of α,β‐diamino acid and ketone derivatives for peptidomimetic studies*
Authors: Timmons C. , Mcpherson L.M. , Chen D. , Wei H.‐X. , Li G.
Published: September 2005

Abstract:  Manganese (IV) oxide was found to catalyze the diamination reaction of α,β‐unsaturated esters and ketones with N,N‐dichloro‐p‐toluenesulfonamide and acetonitrile as the halogen and nitrogen sources. The reaction is convenient to be conducted by simply mixing three reactants in the presence of manganese dioxide catalyst and 4 Å molecular sieves, and provides an easy access to 1‐p‐toluenesulfonyl‐3‐trichloromethyl‐4,5‐imidazoline derivatives, which are useful building blocks for peptidomimetic studies.
The geographic mosaic in predispersal interactions and selection on Helleborus foetidus (Ranunculaceae)
Authors: Rey P. J. , Herrera C. M. , Guitián J. , Cerdá X. , Sánchez-lafuente A. M. , Medrano M. , Garrido J. L.
Published: September 2005

We examine the hierarchical geographic structure of the interaction between a plant, Helleborus foetidus, and its floral herbivores and pollinators (interactors). Six populations from three distant regions of the Iberian Peninsula were used to examine intra- and inter-regional variation in plant traits, interactors and plant fecundity, and to compare, through selection gradient and path analyses, which traits were under selection, and which interactors were responsible for differential selection. Geographic and temporal congruency in interactor-mediated selection was further tested using a recent analytical approach based on multi-group comparison in Structural Equation Models. Most plant traits, interactors and fecundity differed among regions but not between populations. Similarly, the identity of the traits under selection, the selection gradients (strength and/or the direction of the selection) and the path coefficients (identifying the ecological basis for selection) varied inter- but not intra-regionally. Results show a selection mosaic at the broad scale and, for some traits, a link of differential selection to trait differentiation.
Host ploidy, parasitism and immune defence in a coevolutionary snail–trematode system
Authors: Osnas E. E. , Lively C. M.
Published: September 2005

We studied the role of host ploidy and parasite exposure on immune defence allocation in a snail–trematode system (Potamopyrgus antipodarum-Microphallus sp.). In the field, haemocyte (the defence cell) concentration was lowest in deep-water habitats where infection is relatively low and highest in shallow-water habitats where infection is common. Because the frequency of asexual triploid snails is positively correlated with depth, we also experimentally studied the role of ploidy by exposing both diploid sexual and triploid asexual snails to Microphallus eggs. We found that triploid snails had lower haemocyte concentrations than did diploids in both parasite-addition and parasite-free treatments. We also found that both triploids and diploids increased their numbers of large granular haemocytes at similar rates after parasite exposure. Because triploid P. antipodarum have been shown to be more resistant to allopatric parasites than diploids, the current results suggest that the increased resistance of triploids is because of intrinsic genetic properties rather than to greater allocation to defence cells. This finding is consistent with recent theory on the advantages of increased ploidy for hosts combating coevolving parasites.
Analysis of Soil Fertility and Management Effects on Yields of Wheat and Corn in the Rolling Pampa of Argentina
Authors: Alvarez R. , Grigera S.
Published: September 2005

The Rolling Pampa is the most productive region of the Argentine Humid Pampa comprising around 10 Mha. Wheat (Triticum aestivum L.), corn (Zea mays L.), and soya bean [Glycine max (L.) Merr.] are the main grain crops produced. To develop sound cropping strategies, a better understanding of the impact of soil fertility and management on crops is needed. The objective of this study was to develop models for estimating the effects of growing season precipitation, soil fertility and management on wheat and corn yields. Data from 347 wheat and 323 corn field experiments and production fields over six growing seasons were used. Soil, management and weather characteristics were determined and yields were then evaluated. Data were analysed using linear and quadratic models and a quadratic polynomial surface model. Soil fertility, management and rainfall and interactions were analysed. Growing season precipitation correlated with wheat (R2 = 0.42) and corn (R2 = 0.25) yield. Maximum wheat yield was achieved with 350–400 mm rainfall and corn yield reached a plateau around 700 mm. Soil fertility accounted for 33 % of wheat yield variability and 5 % of corn yield variability. Management accounted for 48 and 9 % respectively. Whole polynomial models integrating rainfall, fertilizer N and P rates, soil N and P, previous crop and tillage system accounted for 67 % of wheat yield variability and 51 % of corn yield variability. Soil organic matter was not included in the models but an indirect effect on yield was detected as organic matter correlated with initial soil N levels for both crops. Soya bean as a previous crop had a positive effect on wheat and corn yields. Wheat was insensitive to tillage system but corn yield was higher under no till. N and P fertilization had a two‐ to three‐fold greater impact on yield than soil nutrient levels. As this region is considered to be of high soil fertility and has a history of very low fertilizer consumption, adequate use of N and P fertilization will be essential to maintaining high wheat and corn yields.
Putrescine Increases Floral Retention, Pod Set and Seed Yield in Cold Stressed Chickpea
Authors: Nayyar H.
Published: September 2005

Chickpea (Cicer arietinum L.) is sensitive to cold stress (<8 °C) at its reproductive phase that results in flower abortion, poor pod set and thus reduced yield. Early maturing genotypes are especially more sensitive. In this crop, the metabolic causes underlying cold injury that are imperative to induce cold tolerance are not known. In the present study, the endogenous levels of putrescine (diamine), spermidine (triamine) and spermine (tetramine) were examined in early maturing chickpea genotype ICCV 96029, subjected to chilling temperatures of field (12–15/4–6 °C; average maximum and minimum temperature respectively), at flowering or early podding stage. These were compared with controls growing in warmer conditions (28/12 °C) of the glasshouse. The polyamine levels increased six to nine times because of stress. Relatively, putrescine (PUT) elevation was the highest but short‐lived and its decrease appeared to match with the onset of flower and pod abscission in stressed plants. Compared with controls, chilling injury, observed as electrolyte leakage (EL), increased by 60 % while cellular respiration declined by 68 % in stressed plants. Exogenous application of 10 mm PUT to stressed plants reduced the EL by 29 % and elevated the cellular respiration by 40 %. PUT application at flowering stage resulted in increase of 30, 31, 23 and 25 % in floral retention, pod set, pod retention and fertile pods respectively. At the early podding stage, PUT treatment increased the seed yield per plant, seed number per 100 pods and individual seed weight by 50, 17 and 19 % respectively. The number of single‐seeded pods per plant increased from 4.4 in stressed plants to 12.2 in PUT‐treated plants while the number of double‐seeded pods reduced from 6.2 to 4.3. The number of infertile pods declined from 8.2 in stressed plants to 3.1 in PUT‐treated plants.
Enhancing Seed Germination Rate of Four Turfgrass Genera by Acid Treatments
Authors: Salehi H. , Khosh‐Khui M.
Published: September 2005

Turfgrasses are commonly propagated by seeds. In some genera of turfgrasses, the presence of low germination percentage (GP) or rate is the main problem in seed propagation. The present investigation was undertaken to determine the best concentration and duration of sulphuric acid treatment for seeds of the following turfgrass genera: Cynodon dactylon [L.] Pers.; Festuca rubra L. var. rubra‘Shadow’; Lolium perenne L. ‘Barball’ and Poa pratensis L. ‘Merion’. In the first experiment, sulphuric acid was used with concentrations of 0 (control), 25, 50, 75 and 100 % for 10, 15, 20, 25 and 30 min. In the second experiment, effects of light/dark (16/8) or dark conditions on germination rates of different mentioned genera were investigated using the best specific acid treatments. Each treatment was replicated four times with 100 seeds per replicate kept in plastic Petri dishes. The results indicated that in Cynodon, using 50 % acid for 20–25 min had highest GP and mean daily germination (MDG) in light/dark; in Festuca, using 25 % acid for 15 min had highest GP and MDG in light/dark; in Lolium using 50 % acid for 10 min had highest MDG in dark and in Poa, using 50 % acid for 15–25 min had highest MDG in dark. Both Cynodon and Poa had the highest and Festuca had the lowest GPs. Cynodon and Festuca had the highest and lowest MDGs, respectively. This simple procedure, with considerable results, may be replaced to time‐consuming and expensive methods such as seed priming.
Effect of N Fertilization Rate on Sugar Yield and Non‐Sugar Impurities of Sugar Beets (Beta vulgaris) Grown Under Mediterranean Conditions
Authors: Tsialtas J. T. , Maslaris N.
Published: September 2005

For three successive growing seasons (1999–2001), a completely randomized block design experiment was established at the surrounding area of each of four sugar beet processing plants of Hellenic Sugar Industry SA, Greece (a total of 12 experiments). Nitrogen was applied at five rates (0, 60, 120, 180 and 240 kg N ha−1) and six replications per rate. Nitrogen fertilization had site‐specific effects on quantitative (fresh root and sugar yields) and qualitative (sucrose content, K, Na, α‐amino N) traits. When data were combined over years and sites, fresh root and sugar yields were maximized at high N rates (330.75 and 295 kg N ha−1 respectively), as derived from quadratic functions fitted to data. In three trials, increased N rates had negative effects on root and sugar yield. These sites were characterized by high yield in control plots, light soil texture (sand > 50 %) and low CEC values. When data were converted into relative values (the ratio of the trait values to the control mean of each experiment), root and sugar yield was found to be maximized at higher N rates (350 and 316 kg N ha−1, respectively). Sucrose content was strongly and linearly reduced by the increased N rates when data were combined but a significant reduction with increasing N rates was found in only two sites. Non‐sugar impurities (K, Na, α‐amino N) were positively related to the increased N rates when data were combined. Sodium and α‐amino N showed to be most affected by N fertilization as positive relationships were found in six and eight of 12 locations, respectively. Increased N supply resulted in higher soil NO3‐N concentrations (0–90 cm depth) at harvest which were related with amino N contents in sugar beet roots (in 1999 and 2001).
Germplasm Variability and Environmental Effects on Stem Cellulose and Lignin Concentrations in Alfalfa*
Authors: Schwab P. M. , Lamb J. F. S. , Sheaffer C. C. , Barnes D. K.
Published: September 2005

Stem cellulose and lignin concentrations are major determining factors of alfalfa (Medicago sativa ssp. sativa L.) forage quality. Only limited information is available on the genetic variability and the influence of environmental effects on these two stem‐quality traits. Our objectives were to: evaluate the variability for stem cellulose and lignin concentrations in modern alfalfa germplasms across several harvests; observe the environmental stability of these two quality traits in 32 alfalfa clones selected high or low for either stem cellulose or lignin concentration; and examine the relationships between these two stem‐quality traits and leaf and stem crude protein (CP). Fifty alfalfa entries (cultivars and experimental populations) were established May 1993, and sampled for stem acid‐detergent lignin (ADL), stem acid‐detergent cellulose (ADC), and stem CP on Sep 1993, June and Aug 1994. Clones were vegetatively propagated from individual plants selected for extremes in stem ADL and ADC and transplanted into blocks at two locations in May 1994 and sampled for quality analysis in September 1994. For all samples, leaves were hand‐separated from stems and stem ADL, ADC, CP and leaf CP concentration were determined using near infrared reflectance spectroscopy. Entry differences for stem ADL and ADC were detected only at the June 1994 harvest date in the cultivar study. Spearman's ranked correlations over years in the clonal study demonstrated greater environmental stability for stem ADC (r = 0.70, P ≥ 0.01) than for stem ADL (r = 0.54, P # 0.05). Environmental effects had an impact on both traits, but stem ADC showed greater potential for improving forage quality. Simple correlations showed that decreasing stem ADL or ADC would have minimal effect on leaf CP and may increase stem CP.
Competition and Productivity in Mixture of Oats and Wheat
Authors: Sobkowicz P. , Tendziagolska E.
Published: September 2005

The research assesses the productivity of mixture of oats (Avena sativa) and wheat (Triticum aestivum), and compares two different approaches used in plant competition studies: replacement (substitutive) designs and additive designs. The experiment was carried out on sandy loam soil at the Experimental Station of Agricultural University of Wrocław (Poland). Oats and wheat were grown for grain as sole crops and in 1 : 1 replacement mixtures at three rates of seeding: 150, 300 and 600 viable seeds m−2. These designs allowed mixtures seeded at a rate of 300 and 600 seeds m−2 to be analysed according to either a replacement or an additive approach. In 1999, pure stand wheat and oats–wheat mixture yielded significantly more grain than oats grown alone but in 2000 there was no difference in yield. Wheat outcompeted oats in mixture but the relative competitive ability of the two species changed little with increasing seeding density. Relative yield total (RYT) for grain was significantly >1.0 (RYT = 1.07) in 1999 for the lowest seeding density, showing partial complementarity in use of limiting resources by the species in mixture. Based on grain yields, the results obtained from substitutive and additive mixtures were similar with respect to the relative yields and relative competitive ability of the two species concerned.
Can Leaf Chlorophyll Measures at Differing Growth Stages be used as an Indicator of Winter Wheat and Spring Barley Nitrogen Requirements in Eastern Canada?
Authors: Spaner D. , Todd A. G. , Navabi A. , McKenzie D. B. , Goonewardene L. A.
Published: September 2005

Plant need‐based N management approaches may increase the efficiency of N fertilizer application in wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). The leaf chlorophyll concentration estimated through the SPAD‐502 meter gives a relative assessment of N status in crop. Field trials were conducted near St John's, Newfoundland, between 1997 and 2000 to describe the relationship between winter wheat and spring barley grain yield, protein content, protein yield and SPAD measurements, as affected by differential stage of crop growth, seeding rate and topdress N fertilizer. Grain yield, protein content, and protein yield of winter wheat and spring barley exhibited linear responses to increasing N topdress application rate. SPAD‐502 values were moderately to highly positively correlated with grain yield, protein content, and protein yield as a result of increasing topdress N fertilization, and moderately negatively correlated as a result of increasing seeding rate. It may be difficult to make an N‐application rate recommendation based on SPAD measurements, as a critical SPAD value may vary among years, locations, cultivars and soil characters.
Zum Einsatz von Luzernesilage bei Kühen mit hoher Milchleistung
Authors: Bulang M. , Kluth H. , Engelhard T. , Spilke J. , Rodehutscord M.
Published: September 2005

Studies on the use of lucerne silage as a forage source for high‐yielding dairy cows

It was the main objective of this study to investigate effects of lucerne silage inclusion in maize silage‐based rations on dry matter intake, milk yield and metabolic parameters of high yielding dairy cows. Three total mixed rations (TMR) were used. They contained as the main forage source on a dry matter basis 41.5% maize silage and 12% grass silage (ration maize) or 18% maize silage and 29% of either grass silage (ration grass) or lucerne silage (ration lucerne). Organic matter digestibility, determined with wether sheep, was 77 and 65% for the grass and the lucerne silage, respectively. Each TMR was fed to 4 wether sheep to determine crude nutrient digestibilities. The content of net energy for lactation (NEL), as calculated from digestible crude nutrients, was (MJ/kg dry matter (DM)): 7.1 (maize), 7.2 (grass) and 6.8 (lucerne). Based on the results of a chemical fractionation of crude protein it was calculated that the content of utilisable crude protein (nXP) was not below 167 g/kg DM and that the N balance in the rumen was not negative for all 3 TMR. The TMR were fed for 169 days to at least 28 dairy cows per treatment which were in their first half of lactation. Feed intake, milk performance data and physiological indicators were measured for each individual cow. The DM intake was significantly higher in treatment lucerne (23.2 kg/d) than in treatments grass (21.2 kg/d) and maize (22.6 kg/d). Daily intakes of NEL and nXP were significantly lower in treatment grass than in the other two treatments. Milk yield was significantly higher in treatment maize (41.7 kg/d) than in treatments grass (37.3 kg/d) and lucerne (38.5 kg/d). This was associated with a significantly lower milk fat content in treatment maize (3.5%) in comparison with the other two treatments (3.9% each). Milk protein content was unaffected by treatment (3.4% on average). Similarly, the acetone content of milk was not significantly different between treatments. The β‐hydroxybutyrate content of the deproteinized blood was significantly higher in treatment lucerne at start of lactation, but this difference disappeared in subsequent parts of the experimental period. Measurements of back fat thickness indicated mobilisation and retention of energy by cows during the experimental period to be similar in all treatments. It is concluded that lucerne silage is a suitable forage source for high yielding dairy cows in spite of its low digestibility.
Degradation of transgenic Cry1Ab DNA and protein in Bt‐176 maize during the ensiling process
Authors: Lutz B. , Wiedemann S. , Albrecht C.
Published: September 2005

Maize silage is commonly used as feed for farm animals. The aim of this study was to monitor the time‐dependent degradation of non‐recombinant chloroplast DNA (exemplified by the rubisco gene) in comparison with the recombinant cry1Ab gene in the course of the ensiling process. In parallel, the Cry1Ab protein content and fragment sizes were determined. Fragments of the rubisco (173, 896, 1197, 1753 and 2521 bp) and of the cry1Ab gene (211, 420, 727 and 1423 bp) were selected to investigate the DNA degradation process. The detection of the Cry1Ab protein was performed using an enzyme‐linked immunosorbent assay (ELISA) and immunoblotting. Rubisco gene fragments of 173 bp were still detectable after 61 days, while fragments of 1197 and 2521 bp were detectable up to 30 days and on the first day only respectively. Polymerase chain reaction (PCR) analyses revealed that fragments of the cry1Ab gene with sizes of 211 and 420 bp were detectable up to 61 days, fragments with sizes of 727 and 1423 bp, 30 and 6 days respectively. The ELISA showed a decrease of the Cry1Ab protein in maize silage during the ensiling process. No marked degradation was observed during the first 43 h. Thereafter, a sharp decrease was measured. After 61 days, 23.6 ± 0.9% of the initial Cry1Ab protein was still detectable. Immunoblotting confirmed the results of the ELISA showing a positive signal of approximately 60 kDa size for 8 days of ensiling; no further immunoactive fragments were detectable by immunoblotting. In conclusion, the ensiling process markedly decreases the presence of long functional cry1Ab gene fragments and full size Cry1Ab protein.
Homer 1a enhances spike‐induced calcium influx via L‐type calcium channels in neocortex pyramidal cells
Authors: Yamamoto Kenji , Sakagami Yu , Sugiura Shigeki , Inokuchi Kaoru , Shimohama Shun , Kato Nobuo
Published: September 2005

The scaffold protein family Homer/Vesl serves to couple surface receptors or channels with endoplasmic calcium release channels. Homer 1a/Vesl‐1S is regarded as regulating such coupling in an activity‐dependent manner. The present calcium photometry and electrophysiological measurement revealed that Homer 1a up‐regulates voltage‐dependent calcium channels (VDCCs), depending on inositol‐1,4,5‐trisphosphate (IP3) receptors (IP3Rs). In rat neocortex pyramidal cells, intracellular injection by diffusion from the patch pipette (referred to as ‘infusion’) of Homer 1a protein enhanced spike‐induced calcium increase, depending on both the protein concentration and spike frequency. Induction of this enhancement was disrupted by blockers of key molecules of the mGluR–IP3 signalling pathway, including metabotropic glutamate receptors (mGluRs), phospholipase C and IP3Rs. However, infusion of IP3 failed to mimic the effect of Homer 1a, suggesting requirement for a second Homer 1a‐mediated signalling as well as the mGluR–IP3 signalling. In contrast to the induction, maintenance of this enhancement was independent of the mGluR–IP3 signalling, taking the form of augmented calcium influx via L‐type VDCCs. Presumably due to the VDCC up‐regulation, threshold currents for calcium spikes were reduced. Given that Homer 1a induction is thought to down‐regulate neural excitability and hence somatic spike firing, this facilitation of calcium spikes concomitant with such attenuated firing may well have a critical impact on bi‐directional synaptic plasticity.
Abnormal neurodevelopment, neurosignaling and behaviour in Npas3‐deficient mice
Authors: Brunskill Eric W. , Ehrman Lisa A. , Williams Michael T. , Klanke Justin , Hammer Daniel , Schaefer Tori L. , Sah Renu , Il Gerald W. Dorn , Potter S. Steven , Vorhees Charles V.
Published: September 2005

Npas3 is a member of the bHLH‐PAS superfamily of transcription factors that is expressed broadly in the developing neuroepithelium. To study the function of this gene, mice deficient in Npas3 were generated and characterized. Npas3–/– mice were growth‐retarded and exhibited developmental brain abnormalities that included a reduction in size of the anterior hippocampus, hypoplasia of the corpus callosum and enlargement of the ventricles. A number of behavioural abnormalities were identified in Npas3–/– mice including locomotor hyperactivity, subtle gait defects, impairment of prepulse inhibition of acoustic startle, deficit in recognition memory and altered anxiety‐related responses. Characterization of neurosignaling pathways using several pharmacological agents revealed dysfunctional glutamate, dopamine and serotonin neurotransmitter signaling. Consistent with these findings, we identified a significant alteration in cortical PSD‐95 expression, a PDZ‐containing protein that has been shown to be involved in postsynaptic signal transduction. Together, our observations indicate an important role for Npas3 in controlling normal brain development and neurosignaling pathways.
Cortical efferents of the entorhinal cortex and the adjacent parahippocampal region in the monkey (Macaca fascicularis)
Authors: Muñoz Mónica , Insausti Ricardo
Published: September 2005

Entorhinal cortex (EC) relays information from the hippocampus to the cerebral cortex. The origin of this entorhino‐cortical pathway was studied semiquantitatively and topographically with the use of 23 retrograde tracer injections in cortical areas of the frontal, temporal, and parietal lobes of the monkey. To assess possible alternative, parallel pathways, the parahippocampal region, comprised of temporal pole (TP), perirhinal (PRC), and posterior parahippocampal cortices (PPH), was included in the study. The majority of the cortical areas receive convergent projections from EC and the parahippocampal region. Strong EC layer V output is directed to temporal pole, medial frontal and orbitofrontal cortices, and the rostral part of the polysensory area of the superior temporal sulcus (sts). Moderate EC output is directed to the caudal superior temporal gyrus, area TE, and parietal cortex, and little to none to the lateral frontal cortex. With the exception of the projection to the medial frontal cortex, output from TP, PRC, and PPH surpassed that from EC, although with regional differences. TP layers II–III, V–VI project strongly to all areas injected except parietal cortex and caudal superior temporal gyrus, while PRC layers III/V–VI send strong projections to rostral parts of area TE and sts. PPH layers III/V–VI project heavily to parietal cortex and caudal superior temporal gyrus. These results suggest that the medial temporal output is primarily organized hierarchically, but at the same time, it has multiple exits of information. These parallel, alternative routes may influence local circuitry in the cerebral cortex and participate in the consolidation of declarative memory.
A slowly developing dysfunction of dopaminergic nigrostriatal neurons induced by long‐term paraquat administration in rats: an animal model of preclinical stages of Parkinson's disease?
Authors: Ossowska K. , Wardas J. , Śmiałowska M. , Kuter K. , Lenda T. , Wierońska J. M. , Zięba B. , Nowak P. , Dąbrowska J. , Bortel A. , Kwieciński A. , Wolfarth S.
Published: September 2005

The aim of the present study was to examine the influence of the long‐term paraquat administration on the dopaminergic nigrostriatal system in rats. Paraquat was injected at a dose of 10 mg/kg i.p. for 4–24 weeks. We found that this pesticide reduced the number of tyrosine hydroxylase‐immunoreactive neurons of the substantia nigra; after the 4‐week treatment the reduction (17%, nonsignificant) was confined to the rostrocentral region of this structure but, after 24 weeks, had spread along its whole length and was ≈ 37%. Moreover, it induced a biphasic effect on dopaminergic transmission. First, levels of dopamine, its metabolites and turnover were elevated (4–8 weeks) in the caudate–putamen, then all these parameters returned to control values (12 weeks) and dropped by 25–30% after 24 weeks. The binding of [3H]GBR 12,935 to dopamine transporter in the caudate–putamen was decreased after 4–8 weeks, then returned to control values after 12 weeks but was again decreased after 24 weeks. Twenty‐four‐week paraquat administration also decreased the level of tyrosine hydroxylase (Western blot) in the caudate–putamen. In addition, paraquat activated serotonin and noradrenaline transmission during the first 12 weeks of treatment but no decreases in levels of these neurotransmitters were observed after 24 weeks. The above results seem to suggest that long‐term paraquat administration produces a slowly progressing degeneration of nigrostriatal neurons, leading to delayed deficits in dopaminergic transmission, which may resemble early, presymptomatic, stages of Parkinson's disease.
Unilateral pallidotomy in 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine‐treated common marmosets exhibiting levodopa‐induced dyskinesia
Authors: Iravani Mahmoud M. , Costa Sergio , Al‐Bargouthy Ghassan , Jackson Michael J. , Zeng Bai‐Yun , Kuoppamäki Mikko , Obeso Jose A. , Jenner Peter
Published: September 2005

Pallidotomy paradoxically reduces the intensity of levodopa‐induced dyskinesia without worsening motor symptoms. The reasons for this are not clear and no experimental study has investigated this phenomenon. The objective of this investigation was to evaluate the effects of unilateral pallidotomy on locomotor activity, motor disability and levodopa‐induced dyskinesia in 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine‐treated levodopa‐primed common marmosets. Animals were primed to exhibit dyskinesia by daily administration of levodopa until stable dyskinesia was evoked by each dose. Locomotor activity, motor disability and dyskinesia were assessed weekly at baseline and following an acute levodopa challenge. Prior to pallidotomies, two distinct groups of animals emerged: poor responders to levodopa with mild dyskinesia (Group 1) and those exhibiting a marked increase in motor activity and pronounced dyskinesia (Group 2). Electrolytic lesions were placed in the left internal segment of the globus pallidus. Pallidotomy had no effect on basal or levodopa‐induced motor activity in either group but significantly improved basal motor disability in Group 2. Following pallidotomy, the ability of levodopa to reduce motor disability was significantly increased in both groups. Pallidotomy improved dyskinesia in both Groups 1 and 2 but it was more effective in reducing dystonia compared with chorea. The effect of pallidotomy on dyskinesia in Group 2 was transient, with the intensity of involuntary movements reverting to presurgery levels 4 weeks later. This study shows that in levodopa‐primed, parkinsonian marmosets, placement of discrete globus pallidus lesions can ameliorate levodopa‐induced dyskinesia but not akinesia. This model allows the evaluation of pallidotomy‐induced biochemical changes in dyskinetic primates.
Nicotinic modulation of glutamatergic synaptic transmission in region CA3 of the hippocampus
Authors: Giocomo Lisa M. , Hasselmo Michael E.
Published: September 2005

Cholinergic modulation of synaptic transmission in the hippocampus appears to be involved in learning, memory and attentional processes. In brain slice preparations of hippocampal region CA3, we have explored the effect of nicotine on the afferent connections of stratum lacunosum moleculare (SLM) vs. the intrinsic connections of stratum radiatum (SR). Nicotine application had a lamina‐selective effect, causing changes in synaptic transmission only in SLM. The nicotinic effect in SLM was characterized by a transient decrease in synaptic potential size followed by a longer period of enhancement of synaptic transmission. The effect was blocked by γ‐aminobutyric acid (GABA)ergic antagonists, indicating the role of GABAergic interneurons in the observed nicotinic effect. The biphasic nature of the nicotinic effect could be due to a difference in receptor subtypes, as supported by the effects of the nicotinic antagonists mecamylamine and methyllycaconitine. Nicotinic modulation of glutamatergic synaptic transmission could complement muscarinic suppression of intrinsic connections, amplifying incoming information and providing a physiological mechanism for the memory‐enhancing effect of nicotine.
Frontal and parietal cortical ensembles predict single‐trial muscle activity during reaching movements in primates
Authors: Santucci David M. , Kralik Jerald D. , Lebedev Mikhail A. , Nicolelis Miguel A. L.
Published: September 2005

Previously we have shown that the kinematic parameters of reaching movements can be extracted from the activity of cortical ensembles. Here we used cortical ensemble activity to predict electromyographic (EMG) signals of four arm muscles in New World monkeys. The overall shape of the EMG envelope was predicted, as well as trial‐to‐trial variations in the amplitude and timing of bursts of muscle activity. Predictions of EMG patterns exhibited during reaching movements could be obtained not only from primary motor cortex, but also from dorsal premotor, primary somatosensory and posterior parietal cortices. These results suggest that these areas represent signals correlated to EMGs of arm muscles in a distributed manner, and that the larger the population sampled, the more reliable the predictions. We propose that, in the future, recordings from multiple cortical areas and the extraction of muscle patterns from these recordings will help to restore limb mobility in paralysed patients.
Differential expression and regulation of the cAMP‐selective phosphodiesterase type 4A splice variants in rat brain by chronic antidepressant administration
Authors: D'Sa Carrol , Eisch Amelia J. , Bolger Graeme B. , Duman Ronald S.
Published: September 2005

Chronic antidepressant treatment up‐regulates the cAMP cascade in limbic brain regions, suggesting that activation of this pathway contributes to the therapeutic efficacy of antidepressants. A role for cAMP signaling is supported by the finding that rolipram, a selective inhibitor of cAMP‐specific phosphodiesterases type 4 (PDE4), has antidepressant efficacy in behavioral models of depression and in clinical trials. To elucidate further the role of PDE4 isozymes, we characterized the expression and regulation of PDE4A splice variants (i.e. PDE4A1, PDE4A5, PDE4A8 and PDE4A10) in rat brain by chronic antidepressant treatment. Initial in situ hybridization studies (ISH) revealed high levels of PDE4A1 mRNA in medial septum, diagonal band, olfactory system, hippocampus and cerebellum. PDE4A5 mRNA expression was restricted to the olfactory nuclei, deep cortical layers, dentate and CA1 pyramidal layers. PDE4A10 mRNA was localized in the dentate gyrus and CA1 pyramidal layers. PDE4A8 mRNA was absent in rat brain. We determined the influence of chronic fluoxetine or electroconvulsive seizure (ECS) treatments on PDE4A splice variants expression in various brain regions. ISH analysis indicated that chronic fluoxetine or ECS treatments significantly increased PDE4A1, but not PDE4A5 or PDE4A10, mRNA levels in frontal and parietal cortices. ECS increased PDE4A5 levels in the anterior cingulate and frontoparietal cortices, CA1 and dentate gyrus, whereas chronic fluoxetine or ECS treatment increased PDE4A10 levels in the hippocampus. The differential up‐regulation of PDE4A splice variants suggests compensatory region‐specific responses to the antidepressant‐induced increase in cAMP signaling and suggests that these splice variants may be relevant as targets for antidepressant intervention.
Reduction of GnRH and infertility in the R6/2 mouse model of Huntington's disease
Authors: Papalexi Eugenia , Persson Anna , Björkqvist Maria , Petersén Åsa , Woodman Ben , Bates Gillian P. , Sundler Frank , Mulder Hindrik , Brundin Patrik , Popovic Natalija
Published: September 2005

Reductions in testosterone and luteinizing hormone levels and reduced sexual functions have been reported in Huntington's disease (HD) patients. Atrophy of the reproductive organs and loss of fertility have also been observed in the R6/2 mouse, which is currently the most studied transgenic model of HD. In an effort to define the cause of infertility we studied the expression of gonadotropin‐releasing hormone (GnRH) in the medial septum, diagonal band of Broca and hypothalamus of R6/2 male mice during sexual maturation. We found a progressive reduction in the numbers of GnRH‐immunoreactive neurons in the analysed brain areas of R6/2 mice starting at 5 weeks of age and becoming statistically significant with only 10% of the neurons remaining by 9 weeks of age. Atrophy of testes and seminal vesicles combined with a significant reduction in serum and testicular testosterone levels were detected in 12‐week‐old R6/2mice. These results suggest that infertility in the R6/2 males is due either to death of GnRH neurons or to a reduction in GnRH expression leading to a downstream impairment of the gonadotropic hormones. Gonadotropic hormone replacement did not mitigate weight loss or restore motor function in R6/2 males.
Glutamatergic neurotransmission and protein kinase C play a role in neuron–glia communication during the development of methamphetamine‐induced psychological dependence
Authors: Miyatake Mayumi , Narita Minoru , Shibasaki Masahiro , Nakamura Atsushi , Suzuki Tsutomu
Published: September 2005

Methamphetamine (METH) is a strongly addictive psychostimulant that dramatically affects the central nervous system (CNS). On the other hand, protein kinase C (PKC) plays a major role in cellular regulatory and signalling processes that involve protein phosphorylation. The purpose of this study was to investigate the role of neuronal and astrocytic PKC in changes in the central glutamatergic system induced by METH. We show here thatin vitrotreatment with METH caused the phosphorylation of both neuronal and astrocytic PKC and the activation of astrocytes in cortical neuron/glia co‐cultures. Treatment of cortical neuron/glia co‐cultures with either the PKC activator phorbol 12,13‐dibutyrate (PDBu) or glutamate also caused the PKC‐dependent activation of astrocytes. The PKC inhibitor chelerythrine suppressed the Ca2+responses to glutamate in both cortical neurons and astrocytes. Moreover, a low concentration of PDBu significantly enhanced the Ca2+responses to glutamate, but not to dopamine, in both cortical neurons and astrocytes. Notably, treatment with METH also enhanced the Ca2+responses to glutamate in cortical neurons. The activation of astrocytes induced by METH was also reversed by co‐treatment with glutamate receptor antagonists (ifenprodil, DNQX or MPEP) in cortical neuron/glia co‐cultures. In the conditioned place preference paradigm, intracerebroventricular administration of glutamate receptor antagonists (ifenprodil, DNQX or MPEP) attenuated the METH‐induced rewarding effect. These findings provide evidence that the changes in PKC‐dependent neuronal and astrocytic glutamatergic transmission induced by METH may, at least in part, contribute to the development of psychological dependence on METH.
Distribution of D2 dopamine receptor in the olfactory glomeruli of the rat olfactory bulb
Authors: Gutièrrez‐Mecinas María , Crespo Carlos , Blasco‐Ibáñez José Miguel , Gracia‐Llanes Francisco Javier , Marqués‐Marí Ana Isabel , Nácher Juan , Varea Emilio , Martínez‐Guijarro Francisco José
Published: September 2005

Dopamine plays key roles in the processing of the olfactory information that takes place in the olfactory glomeruli. Previous studies using autoradiography demonstrate that, at the glomerular level, these actions are mainly mediated via activation of D2 dopamine receptors. Moreover, it has been suggested that D2 receptors could be present in the olfactory nerve, where they might modulate the entrance of olfactory input into the brain. Nevertheless, the precise subcellular localization of D2 receptors in the glomerular neuropil has not been investigated. In this report, we show the subcellular distribution of D2 receptors in the glomerular circuits of Wistar rats, using pre‐embedding immunogold‐silver labelling and electron microscopy. Present results demonstrate for the first time the presence of D2 dopamine receptors into the terminals of the olfactory axons. In addition, we demonstrate that D2 receptors are located into presynaptic elements of the glomerular neuropil other than the olfactory axons. These elements include the dendrites of the mitral/tufted cells and the dendrites of a subset of periglomerular cells that are GABAergic and dopaminergic. This distribution pattern provides anatomical support for a wide range of actions of dopamine in the glomerular circuits through presynaptic mechanisms mediated by D2 receptors. These actions would include: (i) modulation of the glutamate release from the olfactory axons to the dendrites of mitral/tufted cells and periglomerular cells; (ii) modulation of glutamatergic synapses from the dendrites of mitral/tufted cells to the dendrites of periglomerular cells and (iii) modulation of the neurotransmission from a subset of GABAergic/dopaminergic periglomerular cells to mitral/tufted cells.
Contribution of the vagus nerve and lamina terminalis to brain activation induced by refeeding
Authors: Timofeeva Elena , Baraboi Elena Dana , Richard Denis
Published: September 2005

Following refeeding, c‐fos expression is induced in a particular set of brain regions that include the nucleus of the solitary tract (NTS), parabrachial nucleus (PB), central amygdala (CeA), paraventricular hypothalamic nucleus (PVH), supraoptic nucleus (SON) and the circumventricular organs. Within the PVH, the expression is particularly intense in the magnocellular division of the nucleus and it is as yet not clear how this activation occurs. The respective contribution of the vagus afferents and lamina terminalis, which conveys signals entering the brain through the forebrain circumventricular organs, has been investigated in rats subjected to a unilateral cervical vagotomy (UCV) or a unilateral lesion of the fibres running within the lamina terminalis (ULT) and projecting to the neuroendocrine hypothalamus. UCV significantly decreased postprandial c‐fos expression in the NTS, PB, CeA and parvocellular division of the PVH. In contrast, ULT impaired postprandial activation of the magnocellular neurons in the PVH and SON. The present study also characterized the types of neurons activated in the PVH and SON during refeeding. In the magnocellular regions, arginine‐vasopressin (AVP) neurons were activated upon refeeding whereas there was no apparent induction of Fos expression in oxytocin cells. In the parvocellular PVH, postprandial Fos was induced only in 30% of the corticotrophin‐releasing factor (CRF) and AVP neurons. The results of the present study suggest that the postprandial activation of the brain requires the integrity of both the vagal‐ and lamina terminalis‐associated pathways.
Post‐ischaemic mild hypothermia inhibits apoptosis in the penumbral region by reducing neuronal nitric oxide synthase activity and thereby preventing endothelin‐1‐induced hydroxyl radical formation
Authors: Van Hemelrijck An , Hachimi‐Idrissi Said , Sarre Sophie , Ebinger Guy , Michotte Yvette
Published: September 2005

Previously, we showed that treatment with resuscitative, post‐ischaemic mild hypothermia (34 °C for 2 h) reduced apoptosis in the penumbra (cortex), but not in the core (striatum) of an endothelin‐1 (Et‐1)‐induced focal cerebral infarct in the anaesthetized rat. Therefore, the purpose of this study was to investigate by which pathways resuscitative mild hypothermia exerts its neuroprotective effect in this model. The amino acids glutamate, serine, glutamine, alanine, taurine, arginine and the NO‐related compound citrulline were sampled from the striatum and cortex of the ischaemic hemisphere using in vivo microdialysis. The in vivo salicylate trapping method was applied for monitoring hydroxyl radical formation via 2,3 dihydroxybenzoic acid (2,3 DHBA) detection. Caspase‐3, neuronal nitric oxide synthase (nNOS) immunoreactivity and the volume of ischaemic damage were determined 24 h after the insult. In both the striatum and the cortex, Et‐1‐induced increases in glutamate, taurine and alanine were refractory to mild hypothermia. However, mild hypothermia significantly attenuated the ischaemia‐induced 2,3 DHBA levels and the nNOS immunoreactivity in the cortex, but not in the striatum. These observations were associated with a decreased caspase‐3 immunoreactivity. These results suggest that mild hypothermia exerts its neuroprotective effect in the penumbra partially by reducing nNOS activity and thereby preventing oxidative stress. Furthermore, we confirm our previous findings that the neuroprotective effect of resuscitative hypothermia is not mediated by changes in ischaemia‐induced amino acid release as they could not be associated with the ischaemia‐induced damage in the Et‐1 rat model.
Physiological hypoxia promotes survival of cultured cortical neurons
Authors: Li Dongdong , Marks Jeremy D. , Schumacker Paul T. , Young Regina M. , Brorson James R.
Published: September 2005

Physiological oxygen (O2) tensions in brain tissues vary widely, from ≈ 5 to 40 Torr (1–6%), encompassing levels of moderate hypoxia that have often been considered neurotoxic in vitro. The effects of such hypoxia were examined in embryonic murine cortical neurons cultured continuously from plating in an atmosphere of 1% O2. Remarkably, cortical neurons thrived in 1% O2, with survival at 7–14 days significantly greater than that of neurons cultured in ambient conditions (20% O2). Immunostaining for microtubule‐associated protein‐2 (MAP‐2) and NeuN confirmed the neuronal identity of surviving cells, and demonstrated robust development of dendritic structures and MAP‐2 expression in hypoxia. Survival of neurons in 20% O2 could be promoted by transfer of medium conditioned by neurons in 1% O2, or by pharmacological induction of hypoxia‐inducible factor‐1α (HIF‐1α), suggesting a possible role for secreted factors under transcriptional regulation by HIF‐1 in the trophic effects of hypoxia. Vascular endothelial growth factor (VEGF), a factor regulated by HIF‐1, was strongly stimulated in neurons cultured in 1% O2. Treatment of neurons with exogenous VEGF partially improved survival in 20% O2, and inhibitors of VEGF action reduced survival of neurons in 1% O2. These data point to the dynamic role played by hypoxia, associated with HIF‐1 up‐regulation, in promoting survival of cortical neurons, in part through stimulation of VEGF expression and release.