172,144 research outputs found
Purification and properties of cowpea mosaic virus RNA replicase
No full textThis thesis concerns the partial purification and properties of an RNA-dependent RNA polymerase (RNA replicase) produced upon infection of Vigna unguiculata plants with Cowpea Mosaic Virus (CPMV). The enzyme is believed to be coded, at least in part, by the virus genome and to be responsible for the replication of the virus RNA.In chapter 1 we describe the scope of the investigations and the motives underlying this thesis.In chapter 2 a literature review is presented of the RNA replicases of viruses containing a single-stranded RNA genome of the plus type. With respect to the prokaryote virus RNA replicases, studies are described on the structure and properties of QB replicase, with special emphasis on the role the individual subunits of the enzyme are playing in the different stages of RNA synthesis. Reviewing the research on animal and plant virus RNA replicases had to be limited necessarily to a description of the isolation and properties of several crude enzyme preparations, since no purified replicases have been obtained and little progress is made with their purification.In chapter 3 we describe the detection of an RNA-dependent RNA polymerase activity which is present in Vigna unguiculata leaves infected with CPMV but not in uninfected leaves. It is shown, that this RNA polymerase activity, which is designated as CPMV replicase and is associated with a membrane fraction, becomes detectable one day after infection and then continues to increase until the fourth day. This membrane-bound replicase activity was found to require Mg 2+ -ions and all four ribonucleoside triphosphates and to be resistant to DNase and actinomycin D. Analysis of the in vitro synthesized RNA products by sucrose gradient centrifugation and treatment with RNases revealed, that the majority consisted of double-stranded RNA species sedimenting at 17S and 20S, probably representing the replicative forms of both virus RNAs. A minor part consists of two single-stranded RNA species, similar in sedimentation rate (26S and 34S) to the virion RNAs. From these results we concluded, that we were dealing with a bound replicase complex most likely representing the replicase involved in virus replication in vivo. Having the final purification of CPMV replicase in view, we were then faced with the solubilization of the enzyme required to continue the purification.In chapter 4 we describe a very gentle and easy method to release the replicase from the membranes without employing detergent. The method consists of a washing procedure involving a Mg 2+ -deficient buffer, and provides several advantages in comparison with other solubilization procedures. Firstly, the solubilized replicase is highly stable, thus facilitating the further purification. Secondly, the release of the replicase from the membranes is rather selective. The majority of proteins is retained in the membrane pellet and the specific activity of the solubilized replicase is increased about 2-3 fold with respect to the membrane-bound replicase. Thirdly, more than 80% of the replicase activity is detached from the membranes. The solubilized replicase can be further purified and freed of endogenous template RNA by DEAE-BioGel. column chromatography to provide a highly stable enzyme dependent on template.In chapter 5 we describe several properties of the DEAE-purified replicase preparation. Replicase activity is not inhibited by a- amanitin, rifampicin, cordycepin, actinomycin D, DNase and orthophosphate but is completely suppressed by pyrophosphate and RNase A plus RNase T 1 . The in vitro RNA synthesis is shown to proceed for at least 15 hours under the following optimal conditions: 8 mM Mg(OAc) 2 or 12 mM MgCl 2 ; 60 mM (NH 4 ) 2 SO 4 , up to 100 mM K(OAc), but KCl as low as possible; pH 8.2; 30 to 34°C; all four ribonucleoside triphosphates present and 5-10 μg of CPMV RNA as template per 15 μg of protein.Having established the optimal conditions for RNA synthesis, we have studied the template specificity using a variety of viral, nonviral and synthetic template RNAs. It is shown that the replicase readily accepts natural RNAs as templates but is unable to efficiently synthesize RNA complementary to the synthetic ribopolymers poly(C), poly(G) and poly(U); poly(A) is able to direct the incorporation of 3 H-UMP, but only at a high concentration (400 μg/ml) and inefficiently with respect to CPMV RNA. Several possibilities to account for the lack of template specificity displayed by CPMV replicase and many other eukaryote replicases, are discussed. It is argued that template specificity does not have to be an intrinsic property of, and a prerequisite for, eukaryote virus RNA replicases to function properly in vivo, taking into account the specific location of the replication process in the cell and the occurrence of host RNA molecules as ribonucleoprotein particles. Moreover, the loss of essential protein factor(s), the possible requirement for primer(s) and the use of non-specific reaction conditions are considered.Initial studies have been carried out on the binding of CM replicase to 32 P-CPMV RNA and, in addition on the size and nature of the in vitro synthesized RNA products. The binding experiments using a nitrocellulose filter technique to detect RNA-protein complexes, demonstrate that the DEAE-purified replicase, but not a corresponding protein preparation isolated from healthy leaves, binds to CM RNA. This binding can be abolished by synthetic poly(A) and poly(U) but not by poly(C), suggesting that the poly(A) on the CM RNA genome comprises a potential part of the replicase binding site. However, further experiments are needed to substantiate this hypothesis.The bulk of the in vitro synthesized RNA was found to consist of 16S RNA and a rather small amount of faster sedimenting RNA (20S-38S), the latter representing single-stranded RNA molecules still attached to their parental template strand. Although about 60% of the RNA products appears to be sensitive to treatment with RNase A plus RNase T 1 , no free, full-length size virus RNA molecules were formed, due to the presence of RNase(s) contaminating the replicase preparation.In chapter 6 we show that the DEAE-purified replicase can be purified further by glycerol gradient centrifugation. This step affords the removal of some proteins predominating in all earlier stages. A final purification of about 150-200 fold relative to the crude extract is achieved. From analysis by polyacrylamide gel electrophoresis of the replicase purified by glycerol gradient centrifugation and of a corresponding protein preparation from mock-infected leaves, we conclude that the replicase still needs additional purification steps to allow its identification. However, the stability of the enzyme seems to offer good prospects to achieve this aim.<p/
Colletes longitarsus Zabel & Kuhlmann 2023, sp. nov.
No full text<i>Colletes longitarsus</i> sp. nov. <p>urn:lsid:zoobank.org:act: 13DBB574-35EF-4A44-BF91-03D0F5E6617D</p> <p>Figs 46, 53</p> Diagnosis <p> The male is best identified by the unique shape of S7 (Fig. 46G) and the 2 nd hind tarsomere, which is narrow and very elongate (Fig. 46F), as otherwise only in <i>C. cyanonitidus</i> (Fig. 17F).</p> Etymology <p>The species is named for its exceptionally elongate second hind tarsomere.</p> Material examined <p> <b>Holotype</b> SOUTH AFRICA – <b>Western Cape Province</b> • ♂; Clanwilliam, Ramskop; 32°10′ S, 18°52′ E; 9 Jul. 1984; V.B. Whitehead leg.; SAMC.</p> Description <p> <b>Female</b></p> <p>Unknown.</p> <p> <b>Male</b></p> <p>BODY LENGH. 9 mm.</p> <p>HEAD. Integument black, antenna brownish ventrally. Face with grayish white to white hairs (Fig. 46B). Clypeus with very dense, small punctures (<0.2 pd). Malar area long, about as long as width of mandibular base. Facial fovea narrow, maximum width about ½ antennal diameter.</p> <p> MESOSOMA. Integument black, legs reddish brown and tarsi yellowish brown (Fig. 46A). Scutum with long, grayish white to yellowish white hairs (Fig. 46C). Mesosomal sides and legs grayish white to white. Disc of scutum medium sized, scattered punctures (0.5–1 pd), integument glabrous, surrounded by dense (<0.2 pd) punctation. Scutellum and metanotum with long, yellowish white hairs, on scutellum intermixed with brown hairs. Upper sloping part of propodeal triangle with short, longitudinal carinae anteriorly, scabriculous posteriorly, vertical part distinctly shagreened and shiny. Hind basitarsus not modified. 2 nd hind tarsomere very elongated (Fig. 46F).</p> <p>METASOMA. Integument black, terga narrowly translucent posteriorly. T1–T4 with slightly bluish shine. T1 covered with long, erect grayish white hairs (Fig. 46D). Disc of T2 with shorter, erect grayish white hairs. Discs of T3–T6 with erect black hairs. T1–T5 with white, narrow posterior tergal hair bands (Fig. 46E). Discs of T1 and T2 with relatively dense (0.5 pd) granulation that is becoming slightly finer and indistinct on posterior tergal depression, interspaces glabrous. S1–S5 with white hair fringes posteriorly, laterally minimal longer than medially. Disc of S2 with long, erect white hairs, S3–S5 with scattered, short white hairs, laterally longer. S7 (Fig. 46G) and gonostylus (Fig. 46H) as illustrated.</p> Distribution <p>Only record is from the type locality in the Cedarberg Mountains (Fig. 53).</p> Phenology <p>Only recorded in July.</p>Published as part of <i>Zabel, Tina & Kuhlmann, Michael, 2023, Taxonomic revision of the southern African Colletes fasciatus species group (Hymenoptera: Colletidae), pp. 1-96 in European Journal of Taxonomy 899</i> on pages 62-64, DOI: 10.5852/ejt.2023.899.2297, <a href="http://zenodo.org/record/8413282">http://zenodo.org/record/8413282</a>
Colletes ascopalis Zabel & Kuhlmann 2023, sp. nov.
No full text<i>Colletes ascopalis</i> sp. nov. <p>urn:lsid:zoobank.org:act: 67E88DE7-EBA7-404B-B8BC-6FE083727252</p> <p>Figs 8, 14</p> Diagnosis <p> Among the species with reduced scopa the female of <i>Colletes ascopalis</i> is characterized by a combination of legs completely red (Fig. 8A), facial fovea relatively broad (width about 1.5 × antennal diameter),</p> <p>apical hair bands of terga 1–2 broad (Fig. 8D–E), medially nearly completely covering tergal depression (Fig. 8D–E) and upper sloping part of propodeal triangle with short longitudinal carinae.</p> Etymology <p>This species is named for its reduced scopa.</p> Material examined <p> <b>Holotype</b> SOUTH AFRICA – <b>Western Cape Province</b> • ♀; Ysterfontein; 33°21′ S, 18°09′ E; Sep. 1960; South African Museum leg.; SAMC.</p> <p> <b>Paratypes</b> SOUTH AFRICA – <b>Northern Cape Province</b> • 1 ♀; Leliefontein, slope; 30°13′58″ S, 18°09′ 52″ E; 31 Aug. 2003; C. Mayer leg.; white trap; CMK • 1 ♀; same collection data as for preceding; 11 Sep. 2003; CMK • 1 ♀; same collection data as for preceding; 15 Sep. 2003; CMK • 1 ♀; same collection data as for preceding; slope 402/1; 5 Sep. 2003; pink trap; CMK • 1 ♀; Remhoogte, plain; 30°14′07″ S, 18°09′56″ E; 31 Aug. 2003; C. Mayer leg.; pink trap; CMK • 1 ♀; Leliefontein, plain; 30°13′54″ S, 18°09′45″ E; 11 Sep. 2003; C. Mayer leg.; white trap; CMK. – <b>Western Cape Province</b> • 2 ♀♀; Ysterfontein; 33°21′ S, 18°09′ E; Sep. 1960; South African Museum leg.; CMK.</p> Description <p> <b>Female</b></p> <p>BODY LENGTH. 11–12 mm.</p> <p>HEAD. Integument black, antenna brown ventrally. Face with short grayish white hairs (Fig. 8B), brown on vertex. Clypeus with fine, dense (<0.2 pd) medium-sized, slightly elongate punctures. Malar area very narrow, about ⅓ width of mandibular base. Facial fovea relatively broad, maximum width about 1.5 × antennal diameter.</p> <p>MESOSOMA. Integument black, coxa and trochanter brown, femur, tibia and tarsi red (Fig. 8A). Scutum with short yellowish brown hairs with numerous slightly longer dark brown hairs intermixed. Mesosomal sides grayish white, few light brown hairs on mesepisternum, legs with yellowish white hairs. Disc of scutum with relative dense (0.5–1 pd) punctation, surrounded by dense (<0.5 pd) punctation, interspaces glabrous (Fig. 8C). Scutellum and metanotum with short yellowish brown hairs, intermixed with longer dark brown hairs on scutellum, plumose on scutellum and medially on metanotum. Upper sloping part of propodeal triangle with short, longitudinal carinae. Vertical part superficially shagreened and shiny, anterior with a few more or less transverse well-developed carinae. Scopa partly reduced, dorsal dark brown and ventral yellowish white (Fig. 8F).</p> <p>METASOMA. Integument black, terga broadly yellowish to reddish translucent posteriorly. T1–T2 with slight bluish shine. Disc of T1 covered with moderately long, erect white hairs, medio-anteriorly with short hairs interspersed (Fig. 8D). Disc of T2 with very short, erect yellowish hairs. T2 with well-developed, relatively broad white basal tomentum (Fig. 8D). Discs of T3–T5 with successively longer, short erect blackish hairs. T1–T5 with white relatively broad posterior tergal hair bands, medially narrower on T1 (Fig. 8E). Disc of T1 with fine and dense punctation (0.5–1 pd), punctures becoming slightly finer and denser on posterior tergal depression, interspaces glabrous (Fig. 8D). Disc of T2 with very fine, dense punctation (<0.5 pd). S2–S5 short white hair fringes, medially very small. Disc of sterna sparsely covered with anterior directed hairs, longer laterally.</p> <p> <b>Male</b></p> <p>Unknown.</p> Distribution <p>Found from the Kamiesberg Mountains in the north down to Ysterfontein in the south (Fig. 14).</p> Phenology <p>Recorded in August and September.</p>Published as part of <i>Zabel, Tina & Kuhlmann, Michael, 2023, Taxonomic revision of the southern African Colletes fasciatus species group (Hymenoptera: Colletidae), pp. 1-96 in European Journal of Taxonomy 899</i> on pages 11-13, DOI: 10.5852/ejt.2023.899.2297, <a href="http://zenodo.org/record/8413282">http://zenodo.org/record/8413282</a>
A new strategy for the stereoselective synthesis of 1,2,3-trisubstituted cyclopropanes
No full textThe stereoselective synthesis of highly functionalized 1,2,3-trisubstituted cyclopropanes 1 and 2, starting from readily available furans 3 or N-protected pyrrole 4, is described. Furthermore, exceptionally high diastereocontrol in agreement with the Felkin-Anh model was observed for the addition of nucleophiles to the title compounds
A new strategy for the stereoselective synthesis of 1,2,3-trisubstituted cyclopropanes
No full textThe stereoselective synthesis of highly functionalized 1,2,3-trisubstituted cyclopropanes 1 and 2, starting from readily available furans 3 or N-protected pyrrole 4, is described. Furthermore, exceptionally high diastereocontrol in agreement with the Felkin-Anh model was observed for the addition of nucleophiles to the title compounds
Colletes carolinae Zabel & Kuhlmann 2023, sp. nov.
No full text<i>Colletes carolinae</i> sp. nov. <p>urn:lsid:zoobank.org:act: 077B6CAC-A291-4ADF-9880-4FBEEAF61943</p> <p>Figs 12–14</p> Diagnosis <p>The female can be separated from that of all other species with a normal scopa by the combination of the following characters: apical hair band of T2 about ¼ width of disc (Fig. 12D–E), malar area narrow (⅓ width of mandibular base), facial fovea slightly broadened (about 1–1.2 × width of antennal flagellum), T6 narrowly rounded and disc of T1 medio-anteriorly without numerous conspicuously short hairs interspersed (Fig. 12D–E). The male can be most easily identified by the unique shape of S7 (Fig. 13G).</p> Etymology <p>The species is dedicated to Dr Carolin Mayer, University of Namur, Belgium. She extensively collected bees in Namaqualand for pollination research and greatly facilitated the exploration of the bee fauna in this area.</p> Material examined <p> <b>Holotype</b> SOUTH AFRICA – <b>Northern Cape Province</b> • ♂; Keiski Mts, 5 km S Farm Nooiensrivier, burned area; 31°45′47″ S, 19°50′17″ E; alt. 1275 m; 18 May 2013; M. Kuhlmann leg.; SAMC.</p> <p> <b>Paratypes</b> SOUTH AFRICA – <b>Northern Cape Province</b> • 1 ♀; Remhoogte, plain, 49/26; 30°14′07″ S, 18°09′56″ E; 16 Aug. 2003; C. Mayer leg.; yellow trap; CMK • 1 ♀; Remhoogte, plain, 390/11; 30°14′04″ S, 18°09′53″ E; 31 Aug. 2003; C. Mayer leg.; yellow trap; CMK • 1 ♂; Leliefontein, slope; 30°13′58″ S, 18°09′52″ E; 7 Sep. 2003; C. Mayer leg.; yellow trap; CMK • 1 ♀; Keiski Mts, 5 km S Farm Nooiensrivier, dolerite hill; 31°45′54″ S, 19°50′17″ E; alt. 1270 m; 29 Aug. 2010; M. Kuhlmann; CMK • 1 ♀; 9 km N Calvinia, Plateau Hantam Mts, near antenna; 31°22′29″ S, 19°47′03″ E; alt. 1570 m; 7 Sep. 2010; M. Kuhlmann leg.; CMK • 1 ♀, 1 ♂; same collection data as for preceding; 30 Aug. 2011; M. Kuhlmann leg.; CMK • 3 ♀♀, 9 ♂♂; same collection data as for preceding; 7 Jun. 2013; CMK • 4 ♀♀; 20 km W Sutherland, Farm Kanolfontein, road side; 32°24′43″ S, 20°27′28″ E; alt. 1385 m; 7 Sep. 2012; M. Kuhlmann leg.; CMK • 1 ♀, 1 ♂; Keiski Mts, 5 km S Farm Nooiensrivier, burned area; 31°45′47″ S, 19°50′17″ E; alt. 1275 m; 18 May 2013; M. Kuhlmann leg.; CMK • 1 ♀; Nieuwoudtville, Flower Reserve East; 31°21′56″ S, 19°08′52″ E; alt. 735 m; 6 Jun. 2013; M. Kuhlmann leg.; CMK • 1 ♀; Keiski Mts, 3 km E Farm M'Vera, shale; 31°45′29″ S, 19°54′13″ E; alt. 1190 m; 15 Sep. 2016; M. Kuhlmann leg.; CMK • 1 ♀; same collection data as for preceding; 19 Aug. 2017; CMK.</p> Description <p> <b>Female</b></p> <p>BODY LENGTH. 11–12 mm.</p> <p>HEAD. Integument black, antenna brown ventrally. Face yellowish gray, with longer dark brown hairs intermixed, along inner eye margins and on vertex with blackish hairs interspersed (Fig. 12B). Clypeus with fine, dense punctures (0.2 pd), punctures slightly elongate; interspaces glabrous (Fig. 12B). Malar area narrow, length about ⅓ width of mandibular base. Facial fovea relatively broad, maximum width about 1–1.2 × antennal diameter.</p> <p>MESOSOMA. Integument black, tarsi often brownish (Fig. 12A). Scutum with long grayish to yellowish white hairs, intermixed with longer dark brown hairs (Fig. 12C). Mesosomal sides and legs grayish to yellowish hairs, mesosomal sides intermixed with dark brown hairs on mesepisternum, tibiae and tarsi with some brown hairs interspersed. Disc of scutum without or with scattered (1–2 pd) fine punctures, integument smooth and shiny, surrounded by dense (<0.5 pd) punctation. Scutellum and metanotum with long yellowish brown hairs, scutellum intermixed with slightly longer dark brown hairs. Upper sloping part of propodeal triangle scabriculous. Vertical part superficially shagreened and shiny, anteriorly with few indistinct more or less transverse carinae. Scopa dark brown dorsally, dark yellowish ventrally (Fig. 12F). Mid femora basally with edge and stout ridge ventrally with brush of hairs.</p> <p>METASOMA. Integument black, terga narrowly translucent posteriorly. T1–T3 with slight bluish shine. T1 densely covered with long, erect yellowish white hairs (Fig. 12D). Disc of T2 with shorter, erect yellowish white hairs. Discs of T3–T5 with successively longer, erect blackish hairs. T2–T5 with broad white posterior tergal hair bands, narrower on T1 (Fig. 12E). Disc of T1 with shallow, fine and relatively dense punctures (1–2 pd), punctures becoming slightly finer and less distinct towards posterior tergal depression. Disc of T2 with very fine and dense punctation (0.5–1 pd); glabrous between punctures. S2–S5 with long, yellowish hair fringes. Discs of sterna sparsely covered with shorter yellowish hairs.</p> <p> <b>Male</b></p> <p>BODY LENGTH. 11–12 mm</p> <p>HEAD. Integument black, antenna dark brown ventrally. Face yellowish white to white hairs, intermixed with black hairs on vertex, on supraclypeal area and along inner eye margins and with brown hairs between antennae (Fig. 13B). Clypeus with very dense, small punctures (<0.2 pd). Malar area narrow, length about ½ width of mandibular base. Facial fovea narrow, maximum width about antennal diameter.</p> <p>MESOSOMA. Integument black, except tarsi often reddish brown (Fig. 13A). Scutum with long yellowish white hairs, intermixed with numerous black hairs (Fig. 13C). Mesosomal sides and legs yellowish white. Mesosomal sides intermixed with some brown hairs. Disc of scutum with medium-sized, scattered punctures (0.5–1 pd), integument glabrous, surrounded by dense punctation (<0.2 pd) (Fig. 13C). Scutellum and metanotum with long, yellowish brown hairs, scutellum intermixed with black hairs. Upper sloping part of propodeal triangle with short, longitudinal carinae anteriorly, scabriculous posteriorly. Vertical part shagreened and shiny without or with some short, more or less transverse carinae anteriorly. Hind basitarsus broadened apically, with prominent long reddish bristles on dorso-apical edge (Fig. 13F). Mid femora with right-angled edge on basal end.</p> <p>METASOMA. Integument black, terga narrowly translucent. T1–T3 with slight bluish shine. T1 densely covered with long, erect yellowish brown hairs (Fig. 13D). Disc of T2 with shorter, erect yellowish brown hairs intermixed with some dark brown hairs posteriorly. Discs of T3–T6 with long erect, blackish hairs. T1–T5 with moderately broad white tergal hair bands posteriorly, T1 slightly narrower medially (Fig. 13E). Discs of T1 and T2 with dense punctures (0.5–1 pd), punctation becoming finer on posterior tergal depression, integument between punctation glabrous (Fig. 13D). S1–S5 with yellowish white hair fringes posteriorly, laterally longer. Discs of sterna covered with yellowish white hairs. S6 with 2 brushes of bristles laterally.</p> Distribution <p>Found in mountainous regions of the Kamiesberg, Hantam, Keiskie and Roggeveld Mountains as well as the Bokkeveld (Fig. 14).</p> Phenology <p>Recorded from May to September.</p>Published as part of <i>Zabel, Tina & Kuhlmann, Michael, 2023, Taxonomic revision of the southern African Colletes fasciatus species group (Hymenoptera: Colletidae), pp. 1-96 in European Journal of Taxonomy 899</i> on pages 13-21, DOI: 10.5852/ejt.2023.899.2297, <a href="http://zenodo.org/record/8413282">http://zenodo.org/record/8413282</a>
Lone mothers' participation in labor market programs for means-tested benefit recipients in Germany
No full text"This paper examines participation in labor market programs such as job subsidies, workfare, and training programs by lone mothers receiving means-tested unemployment benefits in Germany. Since the 2005 Hartz IV labor market policy reforms, expectations that non-employed parents responsible for caring for young children should be ready for employment or labor market program participation have grown stronger. However, discretion for program assignments is left to individual case managers in employment offices. Thus, lone mothers' participation in labor market programs is studied empirically here. This can contribute to determining the extent to which lone mothers are treated as adult workers in interactions with welfare state institutions in Germany. Entries into labor market programs are analyzed on the basis of large-scale administrative data using event-history analysis. Findings are that lone mothers' participation rates in workfare programs and class-room training programs closely approach or even surpass those of single childless women by the time their youngest child is 3 - 5 years old. In the case of programs that give more direct support for entering regular employment, like job subsidies and in-firm training programs, however, lone mothers' participation rates do not reach those of childless single women until their children are 6 - 9 or even 15 - 17 years old." (Author's abstract, IAB-Doku) ((en))allein Erziehende, Mütter, arbeitsmarktpolitische Maßnahme - Erfolgskontrolle, Teilnehmer, Arbeitslosengeld II-Empfänger, Langzeitarbeitslose, Trainingsmaßnahme, Einstiegsgeld, Eingliederungszuschuss, Arbeitsgelegenheit, Kinder, altersspezifische Faktoren
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Sprachaneignung als Streben nach kultureller Existenz: Prozessontologische, soziokulturelle und artikulationstheoretische Ansätze für eine kulturwissenschaftliche Fundierung der Sprachaneignungsforschung
No full textOhm U. Sprachaneignung als Streben nach kultureller Existenz: Prozessontologische, soziokulturelle und artikulationstheoretische Ansätze für eine kulturwissenschaftliche Fundierung der Sprachaneignungsforschung. In: Wolbergs J, Zabel R, Altmayer C, eds. Kulturstudien und Deutsch als Zweitsprache. Deutsch als Fremd- und Zweitsprache. Schriften des Herder-Instituts (SHI). Vol 19. Tübingen: Stauffenburg; 2024: 39-66
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
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