It is demonstrated that acetylcholine released from cholinergic interneurons modulates the excitability of neostriatal projection neurons. Physostigmine and neostigmine increase input resistance (RN) and enhance evoked discharge of spiny projection neurons in a manner similar to muscarine. Muscarinic RN increase occurs in the whole subthreshold voltage range (-100 to -45 mV), remains in the presence of TTX and Cd2+, and can be blocked by the relatively selective M1,4 muscarinic receptor antagonist pirenzepine but not by M2 or M3 selective antagonists. Cs+ occludes muscarinic effects at potentials more negative than -80 mV. A Na+ reduction in the bath occludes muscarinic effects at potentials more positive than -70 mV. Thus, muscarinic effects involve different ionic conductances: inward rectifying and cationic. The relatively selective M2 receptor antagonist AF-DX 116 does not block muscarinic effects on the projection neuron but, surprisingly, has the ability to mimic agonistic actions increasing RN and firing. Both effects are blocked by pirenzepine. HPLC measurements of acetylcholine demonstrate that AF-DX 116 but not pirenzepine greatly increases endogenous acetylcholine release in brain slices. Therefore, the effects of the M2 antagonist on the projection neurons were attributable to autoreceptor block on cholinergic interneurons. These experiments show distinct opposite functions of muscarinic M1- and M2-type receptors in neostriatal output, i.e., the firing of projection neurons. The results suggest that the use of more selective antimuscarinics may be more profitable for the treatment of motor deficits.

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The wood quality from 50-to 70-year-old Tectona grandis trees from an unmanaged forest in East Timor was assessed. The aim was to evaluate teak in mature stands that had undergone uncontrolled disturbances, e.g., fi re and local community usage. Heartwood represented 91% of the tree radius at a height of 1.7 m, and sapwood contained on average nine rings. The mean ring width showed within-tree and between-tree variability. The chemical compositions of heartwood and sapwood were similar. Within-tree chemical variation occurred only in terms of extractives, which increased from the pith (8.3%) to the heartwood-sapwood transition (12.7%) and decreased in the sapwood (9.2%). Overall, the wood properties of teak from a unmanaged forest in East Timor were comparable to those reported for plantation teaks of other origin: 607 kg/m 3 basic density, 3.5% and 5.2% radial and tangential shrinkage, 141 N/mm 2 modulus of rupture, 10 684 N/mm 2 modulus of elasticity, and 50 N/mm 2 maximum crushing strength in compression parallel to the grain. Disturbances on individual tree growth arising from the unmanaged status of the stand were evidenced by higher within-tree variability of ring width. However, the longitudinal and radial variations of wood density and mechanical properties were of low magnitude and in a degree that did not negatively impact on timber quality.

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The composition of birch (Betula pendula Roth.) and eucalypt (Eucalyptus globulus Labill.) barks was studied after grinding and fractioning into different particles sizes. There was a significant difference in the fractionation of both barks in relation to the yield of fines (5.9% and 28.3% of particles under 0.450 for birch and eucalypt, respectively) and of coarser particles over 2 mm (70.7% and 41.4%). The chemical composition of birch and eucalypt barks, as a mass weighed average of all granulometric fractions was, respectively: ash 2.9% and 12.1%; total extractives 17.6% and 6.5% (hydrophilic extractives were dominant), lignin 27.9% and 28.8% and holocellulose 49.8% and 62.6%. Birch bark contained a considerable amount of suberin (5.9%) whereas eucalypt bark contained a very small amount (<1%). The carbohydrate composition differed between birch and eucalypt barks, i.e., respectively, glucose 47.0% and 68.4%, and xylose 33.8% and 23.2% of total neutral monosaccharides. Ash elemental composition was different in both species. Birch bark contained in relation to eucalypt bark, in the 0.250-0.450 mm fraction, more N (0.69% vs. 0.26%) and P (0.075% vs. 0.001%), and less Ca (0.39% vs. 0.62%), K (0.24% vs. 0.31%) and Mg (0.07% vs. 0.15%). High concentration of Zn was found in birch bark (217 mg/kg vs. 11 mg/kg in eucalypt bark). After grinding and granulometric separation, extractives were present preferentially in the finest fraction with an enrichment in dichloromethane and ethanol solubles especially in the case of birch bark. Eucalypt bark had a high content of cellulose and hemicelluloses especially in the coarser fraction. The fibrous character of this fraction shows its potential as a fiber source.