Genital incarceration with metal rings: their safe removal

Strangulation of the genitalia with constricting metal bands presents a difficult problem with removal. We report the easy and safe removal by cutting the metal bands in two places using a hand-held Dremel Moto-Tool [corrected] with a metal cutting disk.

The tooth-width relation of the incisors in closed bite

On the basis of various opinions expressed in the literature, "closed bite" is associated in particular with an impaired front-tooth relation. Applying Tonn's index, evaluation of the records (models and cephalograms) of 1,100 patients, however, yielded no evidence of changes in the width ratio of the front teeth with regard to Angle classes, growth type, axial inclination of the central upper incisors, interincisal angle, or overbite.

Preferential degradation of polyadenylated and polyuridinylated RNAs by the bacterial exoribonuclease polynucleotide phosphorylase

Polyadenylation of mRNA has been shown to target the RNA molecule for rapid exonucleolytic degradation in bacteria. To elucidate the molecular mechanism governing this effect, we determined whether the Escherichia coli exoribonuclease polynucleotide phosphorylase (PNPase) preferably degrades polyadenylated RNA. When separately incubated with each molecule, isolated PNPase degraded polyadenylated and non-polyadenylated RNAs at similar rates. However, when the two molecules were mixed together, the polyadenylated RNA was degraded, whereas the non-polyadenylated RNA was stabilized. The same phenomenon was observed with polyuridinylated RNA. The poly(A) tail has to be located at the 3' end of the RNA, as the addition of several other nucleotides at the 3' end prevented competition for polyadenylated RNA. In RNA-binding experiments, E. coli PNPase bound to poly(A) and poly(U) sequences with much higher affinity than to poly(C) and poly(G). This high binding affinity defines poly(A) and poly(U) RNAs as preferential substrates for this enzyme. The high affinity of PNPase for polyadenylated RNA molecules may be part of the molecular mechanism by which polyadenylated RNA is preferentially degraded in bacterial cells.

YAC rescue of downless locus mutations in mice

Mice with mutations at the downless (dl) locus have defects in hair follicle, tooth, sweat gland, preputial gland, Meibomian gland, and tail development. The dl phenotype is analogous to the human genetic disorder termed autosomal hypohidrotic (or anhidrotic) ectodermal dysplasia (HED). On the basis of the identification of two related transgenic insertional mutations in the downless gene, yeast artificial chromosomes (YACs) were identified that map to the critical region of mouse Chromosome (Chr) 10. To determine which of the YACs contain the dl gene, we generated YAC transgenic mice by mouse embryo microinjections. The 200-kb YAC B25.D9 was found to rescue all of the downless defects. In addition, the transgenic YAC rescued the dominant Sleek (Dlslk) allele. Since the sequences within the YAC are entirely deleted in one of the transgenic mutants, our results establish that Sleek encodes a dominant-negative protein whose effects can be reversed by expression of extra copies of the wild-type locus.

Inversin, a novel gene in the vertebrate left-right axis pathway, is partially deleted in the inv mouse

Visceral left-right asymmetry occurs in all vertebrates, but the inversion of embryo turning (inv) mouse, which resulted following a random transgene insertion, is the only model in which these asymmetries are consistently reversed. We report positional cloning of the gene underlying this recessive phenotype. Although transgene insertion was accompanied by neighbouring deletion and duplication events, our YAC phenotype rescue studies indicate that the mutant phenotype results from the deletion. After extensively characterizing the 47-kb deleted region and flanking sequences from the wild-type mouse genome, we found evidence for only one gene sequence in the deleted region. We determined the full-length 5.5-kb cDNA sequence and identified 16 exons, of which exons 3-11 were eliminated by the deletion, causing a frameshift. The novel gene specifies a 1062-aa product with tandem ankyrin-like repeat sequences. Characterization of complementing and non-complementing YAC transgenic families revealed that correction of the inv mutant phenotype was concordant with integration and intact expression of this novel gene, which we have named inversin (Invs).

3'-Processed mRNA is preferentially translated in Chlamydomonas reinhardtii chloroplasts

3'-end processing of nucleus-encoded mRNAs includes the addition of a poly(A) tail that is important for translation initiation. Since the vast majority of chloroplast mRNAs acquire their 3' termini by processing yet are not polyadenylated, we asked whether 3' end maturation plays a role in chloroplast translation. A general characteristic of the 3' untranslated regions of chloroplast mRNAs is an inverted repeat (IR) sequence that can fold into a stem-loop structure. These stem-loops and their flanking sequences serve as RNA 3'-end formation signals. Deletion of the Chlamydomonas chloroplast atpB 3' IR in strain Delta26 results in reduced accumulation of atpB transcripts and the chloroplast ATPase beta-subunit, leading to weakly photosynthetic growth. Of the residual atpB mRNA in Delta26, approximately 1% accumulates as a discrete RNA of wild-type size, while the remainder is heterogeneous in length due to the lack of normal 3' end maturation. In this work, we have analyzed whether these unprocessed atpB transcripts are actively translated in vivo. We found that only the minority population of discrete transcripts of wild-type size is associated with polysomes and thus accounts for the ATPase beta-subunit which accumulates in Delta26. Analysis of chloroplast rbcL mRNA revealed that transcripts extending beyond the mature 3' end were not polysome associated. These results suggest that 3'-end processing of chloroplast mRNA is required for or strongly stimulates its translation.

The sequence and structure of the 3'-untranslated regions of chloroplast transcripts are important determinants of mRNA accumulation and stability

A general characteristic of the 3'-untranslated regions (3' UTRs) of plastid mRNAs is an inverted repeat (IR) sequence that can fold into a stem-loop structure. These stem-loops are RNA 3'-end processing signals and determinants of mRNA stability, not transcription terminators. Incubation of synthetic RNAs corresponding to the 3' UTRs of Chlamydomonas chloroplast genes atpB and petD with a chloroplast protein extract resulted in the accumulation of stable processing products. Synthetic RNAs of the petA 3' UTR and the antisense strand of atpB 3' UTR were degraded in the extract. To examine 3' UTR function in vivo, the atpB 3' UTR was replaced with the 3' UTR sequences of the Chlamydomonas chloroplast genes petD, petD plus trnR plus trnR, rbcL, petA and E. coli thrA by biolistic transformation of Chlamydomonas chloroplasts. Each 3' UTR was inserted in both the sense and antisense orientations. The accumulation of both total atpB mRNA and ATPase beta-subunit protein in all transformants was increased compared to a strain in which the atpB 3' UTR had been deleted. However, the level of discrete atpB transcripts in transformants containing the antisense 3' UTR sequences was reduced to approximately one-half that of transformants containing the 3' UTRs in the sense orientation. These results imply that both the nucleotide sequences and the stem-loop structures of the 3' UTRs are important for transcript 3'-end processing, and for accumulation of the mature mRNAs.

Electronic measurements of relative tongue-palate contact time. Development and testing for orthodontic functional analysis

The importance of the tongue to the form of the jaws and dental arches has long been accepted. Clear-cut differences in arch width and arch height are observed between mouth and nasal breathing. Course measurements, e.g. duration of tongue contact with the gum, are not feasible with traditional measuring methods. The palatal measuring appliance presented here together with the purpose-developed storage and evaluation equipment permits for the first time continuous 24-hour measurement of tongue contact with the palate. The clinical observation is confirmed by the presented results. Nasal obstruction is associated with lower tongue-palate contact times. In our probands, these times fell by an average of 72% after forced mouth breathing. Since complex movements within the mouth cavity cannot be directly observed, functional analysis relating to the tongue position was previously impossible, at least over a longer period. The measuring device presented here is suitable for analyzing in more detail the diagnostically difficult complex of tongue movements and breathing habits. It might therefore conceivably be used to assess myofunctional disturbances and therapeutic methods.

Dihydroorotat-ubiquinone oxidoreductase links mitochondria in the biosynthesis of pyrimidine nucleotides

Pyrimidines and purine (deoxy)nucleotides are the building blocks of DNA and RNA. Nucleoside diphosphate sugars, e.g. UDP-glucose, are the reactive intermediates in the synthesis of nearly all glycosidic bonds between sugars. In mammals the requirement for pyrimidines is met by UMP de novo synthesis and, to a greater or lesser extent, by salvage of free nucleosides. The exceptional compartmentation of the de novo synthesis with respect to mitochondrially-bound dihydroorotate dehydrogenase ('DHOdehase' or 'DHODH', EC 1.3.99.11) is one focus of the present work. DHODH activity was determined by the dihydroorotate-dependent oxygen consumption or by the UV absorption of the product orotate with mitochondria isolated from rodent and porcine tissues. For comparison, the cytochrome c and choline-dependent oxygen consumption of mitochondria from different tissues was measured. The highest specific activity of the rat DHODH was found in liver (2.3 x 10(-3) mumol/min x mg protein) > kidney > heart. The application of known enzyme inhibitors Brequinar Sodium and Leflunomide for DHODH and sodium cyanide for cytochrome c oxidase verified the specificity of the activity tests used. The relation of DHODH activity versus that of cytochrome c oxidase revealed the lowest ratios in heart mitochondria and the highest in liver mitochondria. Since disorders in the mitochondrial energy metabolism could entail severe impairment of pyrimidine biosynthesis via respiratory-chain coupled DHODH, it is suggested to include improvement of pyrimidine nucleotide status in therapy protocols.

The mechanism of preferential degradation of polyadenylated RNA in the chloroplast. The exoribonuclease 100RNP/polynucleotide phosphorylase displays high binding affinity for poly(A) sequence

Polyadenylation of mRNA in the chloroplast has recently been shown to target the RNA molecule for rapid exonucleolytic degradation. A model has been suggested in which the degradation of chloroplast mRNA is initiated by endonucleolytic cleavage(s) followed by the addition of poly(A)-rich sequences and rapid exonucleolytic degradation. When in vitro transcribed RNAs were incubated with chloroplast protein extract, competition between polyadenylated and non-polyadenylated RNAs for degradation resulted in the rapid degradation of the polyadenylated molecules and stabilization of their non-polyadenylated counterparts. To elucidate the molecular mechanism governing this effect, we determined whether the chloroplast exoribonuclease 100RNP/polynucleotide phosphorylase (PNPase) preferably degrades polyadenylated RNA. When separately incubated with each molecule, isolated 100RNP/PNPase degraded polyadenylated and non-polyadenylated RNAs at the same rate. However, when both molecules were mixed together, the polyadenylated RNA was degraded, whereas the non-polyadenylated RNA was stabilized. In RNA binding experiments, 100RNP/PNPase bound the poly(A) sequence with much higher affinity than other RNA molecules, thereby defining the poly(A)-rich RNA as a preferential substrate for the enzyme. 100RNP/PNPase may therefore be involved in a mechanism in which post-transcriptional addition of poly(A)-rich sequence targets the chloroplast RNA for rapid exonucleolytic degradation.

Comparison of the behavioral and morphological effects of colchicine- or neutral fluid-induced destruction of granule cells in the dentate gyrus of the rat

Virtually complete destruction of dentate gyrus granule cells by colchicine injections produced a persistent incapacity to solve spatial problems in rats. A topographically more selective but only locally complete destruction of granule cells using injections of neutral fluid (NFL) impaired acquisition during the initial stages of Morris water maze testing, thus indicating that limited degeneration of granule cells may weakly but significantly alter spatial learning capabilities. A subamnestic dose (0.08 mg/kg ip) of the NMDA antagonist MK-801 worsened radial maze performance only in NFL-treated rats, suggesting that there may be a synergistic interaction between NMDA blockade and limited granule cell degeneration.

Antiparkinsonian and other motor effects of flupirtine alone and in combination with dopaminergic drugs

In this study we attempted to specify the behavioural profile of the analgesic flupirtine (1, 10 and 20 mg/kg p.o.) in the rat with respect to (i) its antiparkinsonian potential alone and as an adjunct to L-dihydroxyphenylalanine (L-DOPA) in the haloperidol-induced catalepsy (0.5 mg/kg haloperidol i.p.), (ii) locomotion and exploratory behaviour in the open field with holeboard, and (iii) possible psychomotor stimulating effects in the experimental chamber. In the two latter tests, behaviour was additionally challenged by D-amphetamine (2 mg/kg i.p.). In the catalepsy tests (horizontal bar, podium, grid) flupirtine alone was anticataleptic at doses of 10 and 20 mg/kg p.o., and the antiparkinsonian potential of a subthreshold dose of L-DOPA (50 mg/kg p.o.) was potentiated by 1 and 10 mg/kg p.o. flupirtine. On spontaneous forward locomotion in the open field with holeboard, flupirtine (1 and 10 mg/kg p.o.) had no marked effect but increased the frequency and duration of head dips, indicative for augmenting exploratory behaviour. Spontaneous rearing was reduced and D-amphetamine-induced rearing was enhanced by 1 mg/kg p.o. flupirtine. Grooming was reduced by 1 and 10 mg/kg p.o. flupirtine. In contrast, turning and grooming behaviour (spontaneous as well as D-amphetamine-induced) was not markedly influenced by flupirtine in the experimental chamber. Sniffing was increased in this test by 1 mg/kg p.o. flupirtine but not by the higher dose. Flupirtine is highly effective in antagonising neuroleptic-induced catalepsy as well as in potentiating L-DOPA treatment in the rat, suggesting it is a prospective new candidate for the therapy of Parkinson's disease.

Modification of the agar overlay assay: assessment of the influence of acrylics used in orthodontics on proliferation and differentiation of primary and transformed fibroblasts

In orthodontics, removable acrylic appliances are preferably produced from methylmetacrylates. However, in the adjacent oral mucosal tissue, cell damage may be caused by the evaporation of residual monomer. The aim of this study was to modify the classic agar overlay assay in order to apply histochemical methods by comparing conventionally used transformed mouse fibroblasts (L-929) with primary human gingival fibroblasts to further elucidate the term toxicity. While proliferation was assessed via the incorporation of the base analogon bromdesoxyuridine, differentiation was investigated by detection of the fibroblast-specific intermediate filament vimentin. After the monomers had taken effect, reduced proliferation extending over the inhibition area was observed by indirect immunofluorescence, independent of cell type. In contrast to this observation, a few cells within the inhibition area which could not be clearly detected by neutral red staining still exhibited mitotic activity. Detection of the differentiation-specific intermediate filament vimentin was comparable with the degree of neutral red fading visible in the classic agar overlay assay. The study showed that the inhibition areas with primary gingival fibroblasts were smaller (approximately 1/3) after monomer action compared with conventionally applied transformed fibroblasts. The results indicate that the modified assay is comparable with the classic method. Evaluation of neutral red staining with respect to toxic material influence can moreover be supplemented by histochemical studies of typical cell properties.

Addition of destabilizing poly (A)-rich sequences to endonuclease cleavage sites during the degradation of chloroplast mRNA

In this work, we report the posttranscriptional addition of poly(A)-rich sequences to mRNA in chloroplasts of higher plants. Several sites in the coding region and the mature end of spinach chloroplast psbA mRNA, which encodes the D1 protein of photosystem II, are detected as polyadenylylated sites. In eukaryotic cells, the addition of multiple adenosine residues to the 3' end of nuclear RNA plays a key role in generating functional mRNAs and in regulating mRNA degradation. In bacteria, the adenylation of several RNAs greatly accelerates their decay. The poly(A) moiety in the chloroplast, in contrast to that in eukaryotic nuclear encoded and bacterial RNAs, is not a ribohomopolymer of adenosine residues, but clusters of adenosines bounded mostly by guanosines and rarely by cytidines and uridines; it may be as long as several hundred nucleotides. Further analysis of the initial steps of chloroplast psbA mRNA decay revealed specific endonuclease cleavage sites that perfectly matched the sites where poly(A)-rich sequences were added. Our results suggest a mechanism for the degradation of psbA mRNA in which endonucleolytic cleavages are followed by the addition of poly(A)-rich sequences to the upstream cleavage products, which target these RNAs for rapid decay.

The 3' untranslated regions of chloroplast genes in Chlamydomonas reinhardtii do not serve as efficient transcriptional terminators

A general characteristic of the 3' untranslated regions of plastid mRNAs is an inverted repeat sequence that can fold into a stem-loop structure. These stem-loops are superficially similar to structures involved in prokaryotic transcription termination, but were found instead to serve as RNA 3' end processing signals in spinach chloroplasts, and in the atpB mRNA of Chlamydomonas reinhardtii chloroplasts. In order to carry out a broad study of the efficiency of the untranslated sequences at the 3' ends of chloroplast genes in Chlamydomonas to function as transcription terminators, we performed in vivo run-on transcription experiments using Chlamydomonas chloroplast transformants in which different 3' ends were inserted into the chloroplast genome between a petD promoter and a reporter gene. The results showed that none of the 3' ends that were tested, in either sense or antisense orientation, prevented readthrough transcription, and thus were not highly efficient transcription terminators. Therefore, we suggest that most or all of the 3' ends of mature mRNAs in Chlamydomonas chloroplasts are formed by 3' end processing of longer precursors.

CSP41, a sequence-specific chloroplast mRNA binding protein, is an endoribonuclease

Correct 3' processing of chloroplast precursor mRNAs (pre-mRNAs) requires a stem-loop structure within the 3' untranslated region. In spinach, a stable 3' stem-loop-protein complex has been shown to form in vitro between petD pre-mRNA, encoding subunit IV of the cytochrome b6/f complex, and chloroplast proteins. This complex contains three chloroplast stem-loop binding proteins (CSPs), namely, CSP29, CSP41, and CSP55. Here, we report the purification of CSP41 and cloning of the csp41 gene and show that CSP41 is encoded by a single nuclear gene. Characterization of bacterially expressed CSP41 demonstrates that this protein binds specifically to the 3' stem-loop structure and a downstream AU-rich element of petD pre-mRNA and that its binding affinity is enhanced by associating with CSP55. Our data also show that CSP41 has substantial nonspecific endoribonuclease activity. These data suggest that CSP41 could be involved in 3' processing of petD pre-mRNA and/or in RNA degradation. The fact that different reaction conditions favor RNA binding over ribonuclease activities suggests a possible mode of in vivo regulation.

Response of oral mucosal cells to glass ionomer cements

Although glass ionomer cements are generally considered to be tissue-compatible, it has been suggested that unreacted components or setting reaction by-products can affect cell metabolism. The current study examined the effects of constituents leached out of three glass ionomer cements on growth and metabolism of oral epithelial cells. Aseptically prepared discs of Ketac-Cem Radiopaque (KCR), Ketac-Cem Maxicap (KCM) and Fuji I were incubated in Dulbecco's medium for 10 d, with daily medium changes. Cultures of hamster cheek pouch (HCP) cells, a line of hamster buccal pouch epithelial cells, were incubated in control or eluate-containing media for 24 h. Viable cell numbers were determined by the colorimetric MTS assay, and DNA and RNA syntheses were assessed using [3H]thymidine and [3H]uridine incorporation, respectively. Responses to materials were determined by comparison of cell numbers and radioisotope incorporation (counts per minute (cpm) per 1000 cells). Results were analysed by ANOVA and Duncan's multiple range test, then converted to percent control for comparison. The eluates of all three materials from the first 24 h of soaking inhibited HCP cell growth. The number of cells in cultures exposed to Fuji were 88% of control cultures, while those exposed to KCR and KCM were 58% and 59% of control, respectively. The difference between Fuji-exposed and control cultures was significant (P < 0.05). The two Ketac cements were different from Fuji-exposed and control cultures (P < 0.05) but not from each other. All of the materials caused significant increases in labelling of DNA compared to control cultures (P < 0.05) when calculated on a per cell basis, but the materials did not differ from each other. Both Ketac cements also significantly stimulated labelling of RNA per cell compared to control cultures (P < 0.05). All effects of the material decreased over time. Results suggest that leachable components of the materials may affect the rate of progression of HCP cells through the cell cycle, rather than overt toxicity that results in cell death.

Chloroplast mRNA 3'-end processing by a high molecular weight protein complex is regulated by nuclear encoded RNA binding proteins

In the absence of efficient transcription termination correct 3'-end processing is an essential step in the synthesis of stable chloroplast mRNAs in higher plants. We show here that 3'-end processing in vitro involves endonucleolytic cleavage downstream from the mature terminus, followed by exonucleolytic processing to a stem-loop within the 3'-untranslated region. These processing steps require a high molecular weight complex that contains both endoribonucleases and an exoribonuclease. In the presence of ancillary RNA binding proteins the complex correctly processes the 3'-end of precursor RNA. In the absence of these ancillary proteins 3'-end maturation is prevented and plastid mRNAs are degraded. Based on these results we propose a novel mechanism for the regulation of mRNA 3'-end processing and stability in chloroplasts.