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M Wu

Publications and source records attributed to M Wu.

At least 541 records · Page 30Linked to original sources
PubMed1988

Modulation of locomotor activity induced by injections of carbachol into the tegmental pedunculopontine nucleus and adjacent areas in the rat.

The pedunculopontine nucleus (PPN) is a major component of the mesencephalic locomotor region. There is little known, however, about neurotransmitters in the PPN associated with locomotor activity. The purpose of the present study was to investigate a possible modulatory effect of the cholinergic system on locomotion. The effects of application of carbachol (CCh) into the PPN on locomotor activity of freely moving rats were studied. Unilateral injections of CCh into the PPN decreased spontaneous locomotor activity of rats. On the other hand, an increase in locomotor activity resulted from CCh injections into sites surrounding the PPN. These CCh-induced changes in locomotion were no longer observed after pretreatment of the PPN with atropine. Locomotor activity induced by injections of amphetamine into the nucleus accumbens was also reduced to control levels by ipsilateral injections of CCh into the PPn, whereas contralateral injections of CCh were ineffective. The results suggest that the muscarinic cholinergic system has a modulatory influence on locomotor activity presumably by affecting PPN cells involved in relaying locomotion-associated signals. The PPN receives signals from higher structures involved in initiation of locomotion while the muscarinic system seems to play a role in attenuation or inhibition of locomotor behaviour.

Amphetamine↗
PubMed1988

Mutational analysis of the yeast coenzyme QH2-cytochrome c reductase complex.

The synthesis of cytochrome b in yeast depends on the expression of both mitochondrial and nuclear gene products that act at the level of processing of the pre-mRNA, translation of the mRNA, and maturation of the apoprotein during its assembly with the nuclear-encoded subunits of coenzyme QH2-cytochrome c reductase. Previous studies indicated one of the nuclear genes (CBP2) to code for a protein that is needed for the excision of the terminal intervening sequence from the pre-mRNA. We show here that the intervening sequence can promote its own excision in the presence of high concentrations of magnesium ion (50 mM), but that at physiological concentrations of the divalent cation (5 mM), the splicing reaction requires the presence of the CBP2-encoded product. These results provide strong evidence for a direct participation of the protein in splicing, most likely in stabilizing a splicing competent structure in the RNA. The conversion of apocytochrome b to the functional cytochrome has been examined in mutants lacking one or multiple structural subunits of the coenzyme QH2-cytochrome c reductase complex. Based on the phenotypes of the different mutants studied, the following have been concluded. (i) The assembly of catalytically active enzyme requires the synthesis of all except the 17 kDa subunit. (ii) Membrane insertion of the individual subunits is not contingent on protein-protein interactions. (iii) Assembly of the subunits occurs in the lipid bilayer following their insertion. (iv) The attachment of haem to apocytochrome b is a late event in assembly after an intermediate complex of the structural subunits has been formed. This complex minimally is composed of apocytochrome b, the non haem iron protein and all the non-catalytic subunits except for the 17 kDa core 3 subunit.

Apoproteins↗
PubMed1988

Darkness and antibiotics increase the steady-state transcripts of the elongation factor gene (tuf) in Chlamydomonas reinhardtii.

A plasmid library of chloroplast (Cp) DNA from Chlamydomonas reinhardtii was used to screen for transcripts which respond to light. A transcript of R03, a 1,300 bp EcoRI fragment, was identified as a message which accumulates in darkness. The transcribed region of R03 showed extensive sequence homology with the Escherichia coli elongation factor gene, tufA. A gene-specific probe was constructed. Northern blots were used to study the extent and kinetics of accumulation of this transcript in darkness and in the presence of antibiotic inhibitors of Cp ribosomes. For comparison, the effects of darkness and antibiotics on the steady state levels of psbA, rbcL, and 16S rRNA were also studied. We conclude that the tuf transcript shows the greatest increase in darkness and in the presence of antibiotics.

Anti-Bacterial Agents↗
PubMed1988

Similar chemotactic factor for monocytes predominates in different animal models of uveitis.

Anterior uveitis or iritis occurs in a variety of systemic diseases including sarcoid, Behcet's, and spondyloarthritis. Iritis is, therefore, presumed to result from a variety of pathogenetic mechanisms. We hypothesized that unique chemotactic factors should be associated with different etiologies for inflammation. We have tested this hypothesis using rabbit models of anterior uveitis. We have found that aqueous humor generally contained chemotactic activity for monocytes 24 h after an intravitreal injection of endotoxin, killed mycobacteria, or human serum albumin (in a rabbit previously immunized against human serum albumin). Anterior chamber paracentesis resulted in aqueous humor with a high protein content. However, in contrast to the other models of inflammation, paracentesis did not result in a cellular infiltrate in the anterior chamber, and aqueous humor after paracentesis was not chemotactic. For either immunologically mediated inflammation or for inflammation resulting from injection of a killed bacterial product, chemotactic activity could be digested by papain or trypsin and tended to coelute with albumin on either gel filtration or ion-exchange chromatography. These observations suggest that a similar chemotactic factor for monocytes appears to be associated with ocular inflammation that follows either an immune response or injection of a killed bacterial product.

Animals↗
PubMed1988

Differential effects on locomotor activity of injections of procaine into mediodorsal thalamus and pedunculopontine nucleus.

A comparison was made of the contributions to locomotor activity of output projections of the subpallidal region to the mediodorsal thalamus (MD) and to the pedunculopontine nucleus (PPN). Locomotor activity elicited by injections of picrotoxin into the subpallidal region was reduced by the administration of procaine to the pedunculopontine nucleus but not by the administration of procaine to mediodorsal thalamus. Since the pedunculopontine nucleus is part of the mesencephalic locomotor region (MLR) it appears that subpallido-pedunculopontine projections contribute to the locomotor component of adaptive behaviors associated with limbic integrative activities.

Animals↗
PubMed1988

Disruption of food hoarding by injections of procaine into mediodorsal thalamus, GABA into subpallidal region and haloperidol into accumbens.

The contributions of accumbens-subpallido-mediodorsal thalamus (MD) projections to food hoarding were investigated. The number of food pellets hoarded was reduced by bilateral injections of haloperidol into the accumbens, by bilateral injections of GABA into the subpallidal region and by bilateral injections of procaine into the mediodorsal thalamus. Food hoarding was not reduced by bilateral injections of procaine into the pedunculopontine nucleus. It appears that subpallido-mediodorsal thalamus projections are associated with hoarding behavior but not subpallido-pedunculopontine projections.

Animals↗
PubMed1988

Cell-cycle regulation as a mechanism for targeting proteins to specific DNA sequences in Tetrahymena thermophila.

Transcriptionally active macronuclei and transcriptionally inert micronuclei of the ciliated protozoan Tetrahymena thermophila contain similar DNA sequences but have very different histones associated with the linker regions of chromatin. In situ hybridization showed that a gene coding for micronuclear linker histone is expressed only in association with micronuclear DNA replication, whereas the gene for macronuclear H1 histone is expressed during macronuclear (but not during micronuclear) S phase. These results indicate that cell-cycle regulation plays an important role in directing proteins to the appropriate nucleus in Tetrahymena and that the replication-expression model [Gottesfeld, J. & Bloomer, L. S. (1982) Cell 28, 781-791; Wormington, W. M., Schlissel, M. & Brown, D. D. (1983) Cold Spring Harbor Symp. Quant. Biol. 47, 879-884] for establishing appropriate transcriptionally active or repressed chromatin complexes during DNA replication is generally applicable.

Animals↗
PubMed1988

Clinical features and history of the destructive lung disease associated with alpha-1-antitrypsin deficiency of adults with pulmonary symptoms.

Alpha-1-antitrypsin (alpha 1AT) deficiency is a hereditary disorder characterized in adults by a high risk for the development of severe destructive lung disease at an early age. The present study was designed to draw conclusions concerning the characteristics of a referral population of 124 patients with alpha 1AT deficiency and symptomatic emphysema. Typically, the alpha 1AT level was 30 mg/dl, and the alpha 1AT phenotype was almost always PiZZ. The individuals in this population were most often male, caucasian, and ex-smokers, and they had become dyspneic between 25 and 40 yr of age. Most routine blood tests were normal. The chest radiographs and ventilation-perfusion studies typically showed abnormalities with a lower zone distribution, and about one third of the study population had evidence suggestive of pulmonary hypertension. Lung function tests were typical for emphysema; the FEV1 and DLCO were the parameters most dramatically reduced, and the annual rate of decline of those parameters was greater than that of the general population. The cumulative probability of survival of this population indicated a significantly shortened lifespan with a mean survival of 16% at 60 yr of age compared with 85% for normal persons.

Adolescent↗
PubMed1988

Synthesis of glucuronides of propafenone and 5-hydroxypropafenone by Sepharose-bound uridine 5'-diphosphoglucuronyltransferase.

Propafenone (Rytmonorm) and its in vivo metabolite 5-hydroxypropafenone were glucuronidated by agarose-bound uridine 5'-diphospho (UDP)-glucuronyltransferase from bovine liver in the presence of UDP-glucuronic acid. The identification of the synthesized glucuronides was based on the specific enzymatic hydrolysis, by mass spectrometry and by chromatographic comparison with isolated metabolites from dog and man. The glucuronidation of propafenone and 5-hydroxypropafenone followed Michaelis-Menten kinetics up to substrate concentration of 0.4 mmol/l (propafenone) and 0.3 mmol/l (5-hydroxypropafenone). The pH optima were 7.5 and 8.0, respectively. The reaction was linear up to 30 min and for a protein concentration between 1 and 5 mg per assay. 5-Hydroxypropafenone showed the best affinity with a Km value of 1.4 mmol/l, in contrast to 11.6 mmol/l for propafenone. The use of agarose-bound UDP-glucuronyltransferase offers the possibility to synthesize propafenone glucuronide and 5-hydroxypropafenone glucuronide which are needed for kinetic and pharmacological studies in man and animal.

Animals↗
PubMed1988

G-banded chromosome analyses of mucosal epithelium adjacent to esophageal cancer (EC)--some consistent chromosomal changes.

G-banded chromosomes of primary cultures taken from mucosal epithelium adjacent to esophageal cancer (EC) were first analyzed. Consistent chromosomal changes, i.e. marker chromosomes, appeared in 2 of seven specimens of esophageal epithelium. Some of the marker chromosomes are very similar to those found in EC8501 cell line. These results imply that the cytogenetic analyses of the mucosal epithelium adjacent to EC may detect the numerical and structural chromosome aberrations occurring at the very beginning of carcinogenesis of esophageal epithelium.

Adenocarcinoma↗
PubMed1987

Mitochondrial and cytoplasmic fumarases in Saccharomyces cerevisiae are encoded by a single nuclear gene FUM1.

Respiratory defective pet mutants of Saccharomyces cerevisiae assigned to complementation group G5 are deficient in fumarase. A representative mutant from this complementation group was used to clone a nuclear gene (FUM1) whose sequence encodes a protein homologous to bacterial fumarase. Based on the primary structure homology and the elevated levels of fumarase in transformants harboring FUM1 on a multicopy plasmid, this gene is concluded to code for yeast fumarase. In wild type yeast, fumarase is detected in both mitochondria and the soluble postribosomal protein fraction. Several lines of evidence indicate that the two compartmentally distinct fumarases are isoenzyme products of FUM1. Mutations in FUM1 simultaneously abolish both activities. Transformation of a fumarase mutant with a plasmid containing FUM1 leads to increased fumarase activity in mitochondria and in the postribosomal supernatant fraction. Transformation of the same mutant with a plasmid construct in which the region of FUM1 coding for the amino-terminal 17 amino acids of fumarase is deleted results in a preferential increase of nonmitochondrial fumarase. Northern and S1 nuclease analysis of fumarase transcripts in wild type yeast and in a mutant transformed with FUM1 on an episomal plasmid indicate that the gene is transcribed from multiple start sites, some of which are located inside the coding sequence. The major transcript presumed to code for mitochondrial fumarase has a 5'-untranslated leader of 185 nucleotides. The most abundant shorter transcripts have 5' termini from 57 to 68 nucleotides downstream of the first ATG; their translation products lacking the amino-terminal mitochondrial import signal are proposed to target fumarase to the cytoplasm.

Amino Acid Sequence↗
PubMed1987

Anatomical and electrophysiological evidence for a projection from the medial preoptic area to the 'mesencephalic and subthalamic locomotor regions' in the rat.

There is considerable physiological evidence indicating that the medial preoptic area plays an important role in neural circuits mediating ingestive, thermoregulatory, and reproductive behaviors, all of which involve foraging. The current series of anatomical and electrophysiological experiments was therefore designed to characterize a direct projection from the medial preoptic area to a region in the zona incerta just dorsal to the subthalamic nucleus, which appears to lie within the 'subthalamic locomotor region', and to the pedunculopontine nucleus, which lies within the 'mesencephalic locomotor region'. First, implants of the fluorescent tracer True blue were placed in the pedunculopontine nucleus, and retrogradely labeled neurons were consistently found in dorsal regions of the medial preoptic nucleus, anteroventral preoptic nucleus, rostral tip of the medial preoptic area, lateral parts of the medial preoptic area, and median preoptic nucleus. Second, combined retrograde-immunostaining experiments indicated that a small number of galanin-stained neurons in the rostral tip of the medial preoptic area project to the pedunculopontine nucleus, whereas in nearby regions some galanin- or neurotensin-stained neurons in the lateral preoptic area, and some neurotensin-stained neurons in the substriatal gray appear to project to the pedunculopontine nucleus, as do some neurotensin- or corticotropin releasing factor (CRF)-stained cells in the bed nucleus of the stria terminalis. Third, injections of the anterograde tracer Phaseolus vulgaris leukoagglutinin (PHA-L) into various parts of the medial preoptic area all labeled axons with terminal boutons in the caudal zona incerta and pedunculopontine nucleus. Fourth, single-pulse stimuli were delivered to the zona incerta and pedunculopontine nucleus and the location of antidromically activated neurons in the medial preoptic area was mapped using extracellular recordings. Somewhat less than one-third of the cells recorded from in the medial preoptic area were antidromically activated from either site and some 14% were influenced from both sites. The application of a reciprocal collision test to a small number of neurons suggested that at least some neurons in the medial preoptic area may send collaterals to both sites. And fifth, injections of procaine into the zona incerta were shown to block the antidromic activation of medial preoptic neurons by single-pulse stimulation of the pedunculopontine nucleus.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Ventral pallidum projections to mediodorsal nucleus of the thalamus: an anatomical and electrophysiological investigation in the rat.

Horseradish peroxidase (HRP) and single unit recording experiments were done in rats to investigate neural connections from the ventral pallidal region to the mediodorsal nucleus of the thalamus (MD). In the first series, following the diffusion or iontophoretic injection of HRP into the MD, retrogradely labeled neurons were observed throughout the rostrocaudal extent of the ipsilateral ventral pallidum. Most of the labeled neurons were found in an area between the nucleus of the diagonal band and the ventral aspect of the substantia innominata subcommissuralis. Additional labeled neurons were found in the ventral aspect of the globus pallidus and substantia innominata sublenticularis. In the second series, the region shown to contain labeled neurons was explored for single units antidromically activated by single pulse stimulation of the MD in urethane anesthetized rats. One hundred and fifty-nine single units in the subpallidal area were antidromically activated with latencies corresponding to conduction velocities of 0.2-3.9 m/s. A greater percentage of units in the subcommissural region (50.3%) were activated antidromically as compared to the sublenticular region (27.4%). In the third series, the MD was explored for single units which responded orthodromically to stimulation of the ventral pallidum. Fifty-eight percent (40/69) of MD units responded to stimulation of the subcommissural substantia innominata, whereas 90% (72/80) MD units responded to stimulation of the sublenticular substantia innominata. The most frequent type of orthodromic response observed in MD neurons was inhibition with short onset latencies (less than 10 ms). These data provide anatomical and electrophysiological evidence for the existence of direct pathways from the ventral pallidum to the MD and suggest that this projection is part of a corticosubcortical loop through which the frontal cortex with the ventral striatum and pallidum may contribute to motor function.

Animals↗