1a 2a Research Articles

Causes of Death in Cutaneous T-Cell Lymphoma Patients

Background: The advancing evolution toward a Th2 immune environment confers a progressive immunosuppression in patients with longstanding cutaneous T-cell lymphoma (CTCL). The conjunction of the disease-related immunosuppression as well as the immunosuppressive character of some CTCL treatments increase the risk of infectious and neoplastic diseases, sometimes with fatal outcomes. Objectives: The aim of the study was to prospectively study the causes of death in a cohort of CTCL patients, in a tertiary university skin cancer center. Methods: All CTCL patients who died between 2008 and 2020 were included. The cause of the death was classified as directly or indirectly related or unrelated to CTCL. Results: Over the study period, 31 (13F/18m) patients with CTCL died (mean age: 75.2 years), mean delay between diagnosis and death: 3.2 years (min: 1, max: 12 years), 58.1% of death causes were classified as indirect (infection), 12.9% directly related (blastic transformation), 22.5% unrelated, and 6.5% of unknown cause. 51.6% of mycosis fungoides (MF) patients who died had early-stage disease (1A–2A) or were on remission. 45.2% of dead patients had advanced-stage MF (2B–4B). Mean CRP level is increased in patients who died from infection whereas LDH level increased in patients with blastosis. A tertiary center is expected to manage of a higher proportion of CTCL patients with advanced-stage disease. Conclusions: As infection represented more than 50% of the causes of death in CTCL patients, particular attention should be given to preventive measures such as anti-infective vaccination. Regular surveillance of CRP and LDH levels could be helpful for follow-up of MF patients, respectively, with regards to infection and blastosis.

Parafoveal degradation during reading reduces preview costs only when it is not perceptually distinct.

There is a growing understanding that the parafoveal preview effect during reading may represent a combination of preview benefits and preview costs due to interference from parafoveal masks. It has been suggested that visually degrading the parafoveal masks may reduce their costs, but adult readers were later shown to be highly sensitive to degraded display changes. Four experiments examined how preview benefits and preview costs are influenced by the perception of distinct parafoveal degradation at the target word location. Participants read sentences with four preview types (identity, orthographic, phonological, and letter-mask preview) and two levels of visual degradation (0% vs. 20%). The distinctiveness of the target word degradation was either eliminated by degrading all words in the sentence (Experiments 1a–2a) or remained present, as in previous research (Experiments 1b–2b). Degrading the letter masks resulted in a reduction in preview costs, but only when all words in the sentence were degraded. When degradation at the target word location was perceptually distinct, it induced costs of its own, even for orthographically and phonologically related previews. These results confirm previous reports that traditional parafoveal masks introduce preview costs that overestimate the size of the true benefit. However, they also show that parafoveal degradation has the unintended consequence of introducing additional costs when participants are aware of distinct degradation on the target word. Parafoveal degradation appears to be easily perceived and may temporarily orient attention away from the reading task, thus delaying word processing.

The association of blood lead levels and renal effects may be modified by genetic combinations of Metallothionein 1A 2A polymorphisms

Metallothionein (MT) is a protein with function of heavy metal detoxification. However, studies about how single nucleotide polymorphisms (SNPs) of MT genes influence lead nephropathy are relatively scarce. Therefore, our aim is to investigate the association between blood lead levels and renal biomarkers and to study whether this association is influenced by the combination of MT1A and MT2A SNPs. Blood lead, urinary uric acid (UA), and urinary N-acetyl-beta-d-glucosaminidase (NAG) levels were analyzed from 485 participants. Genotyping were performed on MT1A SNPs (rs11640851 and rs8052394) and MT2A SNPs (rs10636 and rs28366003). The combined MT1A 2A SNPs were divided into 16 groups. Among renal biomarkers, urinary UA was negatively significant associated with the time-weighted index of cumulative blood lead (TWICL), while urinary NAG was positively significant with TWICL. Furthermore, the association between urinary UA and TWICL was significantly modified by group 6 of combined SNPs (MT1A 2 A SNPs combination were AAAGGGAA, ACAGGGAA, and ACGGGGAA). In conclusion, the negative association of urinary UA and TWICL is modified by group 6, which means participants of group 6 are more susceptible to lead nephrotoxicity.

Comparações sonoras e morfométricas entre populações de Arremon taciturnus no Nordeste do Brasil

Estudos recentes apontam que as florestas estacionais do nordeste brasileiro são formadas por duas unidades biogeográficas distintas, uma relacionada a Floresta Atlântica costeira e outra com os domínios da caatinga. Esta pesquisa pretendeu verificar se existe algum grau de diferenciação morfométrica e acústica entre as populações de Arremon taciturnus (Tico-tico-de-bico-preto) em florestas de altitude no Nordeste do Brasil, localizadas a leste e a oeste do planalto da Borborema. Com esta finalidade foram realizados testes paramétrico (teste t) e não paramétrico (teste U), de acordo com a normalidade dos dados acústicos, analisando se existe diferença significativa entre os parâmetros vocais das populações. Para verificar se existem diferenças biométricas entre as áreas estudadas foi realizada uma análise discriminante e de correspondência. Estas, por sua vez, não apresentaram diferença. Entretanto, as análises bioacústicas apontaram diferenças em parâmetros do canto como número de notas e em parâmetros como duração da 1ª, 2ª, e 3ª nota da segunda parte do canto. A. taciturnus é uma espécie que possui capacidade para aprendizado do canto. Desta forma, as diferenças encontradas em alguns parâmetros vocais pode ser indício de uma variação interespecífica nas populações, chamadas de dialetos vocais.

Mixed ligand copper(II) complexes of 1,10-phenanthroline with tridentate phenolate/pyridyl/(benz)imidazolyl Schiff base ligands: Covalent vs non-covalent DNA binding, DNA cleavage and cytotoxicity

A series of copper(II) complexes of the types [Cu(L)(phen)](ClO4) 1–2, where HL is a tridentate ligand with two nitrogen and one oxygen donor atoms (2NO) such as 2-(2-(1H-benzimidazol-2-yl)ethyliminomethyl)phenol (HL1) and 2-(2-(1H-benzimidazol-2-yl)ethyl-imino)methyl)-4-methylphenol (HL2), phen is 1,10-phenanthroline and [Cu(L)(phen)](ClO4)23–6, where L is a tridentate ligand with three nitrogen donor atoms (3N) such as (2-pyridin-2-ylethyl)pyridin-2-ylmethyleneamine (L3), 2-(1H-benzimidazol-2-yl)ethyl)-pyridin-2-yl-methyleneamine (L4), 2-(1H-benzimidazol-2-yl)ethyl)(1H-imidazol-2-ylmethylene)-amine (L5) and 2-(1H-benzimidazol-2-yl)ethyl)(4,4a-dihydroquinolin-2-ylmethylene)amine (L6), has been isolated and characterized by different spectral techniques. In single crystal X-ray structures, 1 possesses square pyramidal distorted trigonal bipyramidal (SPDTBP), geometry whereas 3 and 4 possess trigonal bipyramidal distorted square pyramidal (TBDSP) geometry. UV-Vis and fluorescence spectral studies reveal that the complexes 1–6 bind non-covalently to calf thymus DNA more strongly than the corresponding covalently bound chlorido complexes [Cu(2NO)Cl] 1a–2a and [Cu(3N)Cl2] 3a–6a. On prolonged incubation, all the complexes 1–6 exhibit double strand cleavage of supercoiled (SC) plasmid DNA in the absence of an activator. Also, they exhibit cytotoxicity against human breast cancer cell lines (HBL-100) more potent than their corresponding chlorido complexes 1a–6a, and have the potential to act as efficient cytotoxic drugs.

Aristatosides A-C, hederagenin-type triterpene saponins from Cephalaria aristata

Three hederagenin-type triterpene saponins; 3-O-α-l-rhamnopyranosyl-(1→4)-β-d-glucopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-[β-d-glucopyranosyl-(1→3)-]-α-l-arabinopyranosyl hederagenin 28-O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl ester (aristatoside A, 1), 3-O-α-l-rhamnopyranosyl-(1→2)-β-d-xylopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-[-β-d-glucopyranosyl-(1→3)-]-α-l-arabinopyranosyl hederagenin 28-O-β-d-glucopyranosyl-(1→6)-β-d-glucopyranosyl ester (aristatoside B, 2) and 3-O-β-d-xylopyranosyl-(1→4)-β-d-glucopyranosyl-(1→4)-β-d-xylopyranosyl-(1→3)-α-l-rhamno-pyranosyl-(1→2)-α-l-arabinopyranosyl hederagenin (aristatoside C, 3) have been isolated together with ten known compounds including nine triterpenic and one steroidal glycosides from the aerial parts of Cephalaria aristata (Dipsacaceae). Two prosapogenins (1a–2a) were also obtained after alkaline hydrolysis of the bisdesmosidic compounds 1–2. The structures of all compounds were elucidated by extensive evaluation of the spectroscopic data (1D and 2D NMR, HR-ESI/MS), as well as the chemical examinations. The antimicrobial effects of compounds 1–3 and prosapogenins 1a–2a were evaluated against Gram-positive, Gram-negative bacteria and unicellular yeast C. albicans by MIC method.

Synthesis, spectral characterization and antimicrobial studies of novel s-triazine derivatives

A series of fifteen novel triazinyl derivatives, with various natural nucleobases by mono, di and tri substitution in cyanuric chloride at the 2,4- and/or 6-positions was synthesized. Target molecules were synthesized by stoichiometric addition of various nucleophiles to cyanuric chloride in the presence of suitable base. The structural characterizations of all the compounds were made by spectral and analytical techniques, IR, 1H NMR, 13C NMR, and 2D NMR (HSQC, HMBC), mass spectral and elemental analysis. All the synthesized compounds were screened for in vitro antimicrobial activity against a panel of selected bacterial and fungal strains using Streptomycin and Amphotericin B as standards. The minimum inhibition concentration (MIC) results revealed that most of the purine (1a–2a, 1b–2b, and 1c–2c) compounds exhibit excellent activity against selected bacterial and fungal strains.

Plectin interacts with the rod domain of type III intermediate filament proteins desmin and vimentin

Plectin is a versatile cytolinker protein critically involved in the organization of the cytoskeletal filamentous system. The muscle-specific intermediate filament (IF) protein desmin, which progressively replaces vimentin during differentiation of myoblasts, is one of the important binding partners of plectin in mature muscle. Defects of either plectin or desmin cause muscular dystrophies. By cell transfection studies, yeast two-hybrid, overlay and pull-down assays for binding analysis, we have characterized the functionally important sequences for the interaction of plectin with desmin and vimentin. The association of plectin with both desmin and vimentin predominantly depended on its fifth plakin repeat domain and downstream linker region. Conversely, the interaction of desmin and vimentin with plectin required sequences contained within the segments 1A–2A of their central coiled-coil rod domain. This study furthers our knowledge of the interaction between plectin and IF proteins important for maintenance of cytoarchitecture in skeletal muscle. Moreover, binding of plectin to the conserved rod domain of IF proteins could well explain its broad interaction with most types of IFs.

Synthesis and Characterization of Di‐ and Tricarbonylhydridomanganese(I) Complexes

AbstractHydrido complexes [MnH(CO)3L1–3] [L1 = 1,2‐bis‐(diphenylphosphanoxy)‐ethane (1); L2 = 1,2‐bis‐(diisopropylphosphanoxy)ethane (2); L3 = 1,3‐bis‐(diphenylphosphanoxy)‐propane (3)] were prepared by treating [MnH(CO)5] with the appropriate bidentate ligand by heating to reflux. Photoirradiation of a toluene solution of complexes 1 and 2 in the presence of PPhn(OR)3–n (n = 0, 1; R = Me, Et) leads to the replacement of a CO ligand by the corresponding monodentate phosphite or phosphonite ligand to give new hydrido compounds of formula [MnH(CO)2(L1–2)(L)] [L = P(OMe)3 (1a–2a); P(OEt)3 (1b–2b); PPh(OMe)2 (1c–2c); PPh(OEt)2 (1d–2d)]. All complexes were characterized by IR, 1H, 13C and 31P NMR spectroscopy. In case of compounds 2 and 3, suitable crystals for X‐ray diffraction studies were isolated.

Evidence for alternate states of Cucumber mosaic virus replicase assembly in positive- and negative-strand RNA synthesis

Cucumber mosaic virus (CMV) encodes two viral replication proteins, 1a and 2a. Accumulating evidence implies that different aspects of 1a–2a interaction in replication complex assembly are involved in the regulation of virus replication. To further investigate CMV replicase assembly and to dissect the involvement of replicase activities in negative- and positive-strand synthesis, we transiently expressed CMV RNAs and/or proteins in Nicotiana benthamiana leaves using a DNA or RNA-mediated expression system. Surprisingly, we found that, even in the absence of 1a, 2a is capable of synthesizing positive-strand RNAs, while 1a and 2a are both required for negative-strand synthesis. We also report evidence that 1a capping activities function independently of 2a. Moreover, using 1a mutants, we show that capping activities of 1a are crucial for viral translation but not for RNA transcription. These results support the concept that two or more alternate states of replicase assembly are involved in CMV replication.

CRP Binding and Transcription Activation at CRP-S Sites

In Haemophilus influenzae, as in Escherichia coli, the cAMP receptor protein (CRP) activates transcription from hundreds of promoters by binding symmetrical DNA sites with the consensus half-site 5′-A 1A 2A 3T 4G 5T 6G 7A 8T 9C 10T 11. We have previously identified 13 H. influenzae CRP sites that differ from canonical (CRP-N) sites in the following features: (1) Both half-sites of these noncanonical (CRP-S) sites have C 6 instead of T 6, although they otherwise have an unusually high level of identity with the binding site consensus. (2) Only promoters with CRP-S sites require both the CRP and Sxy proteins for transcription activation. To study the functional significance of CRP-S site sequences, we purified H. influenzae ( Hi)CRP and compared its DNA binding properties to those of the well-characterized E. coli ( Ec)CRP. All EcCRP residues that contact DNA are conserved in HiCRP, and both proteins demonstrated a similar high affinity for the CRP-N consensus sequence. However, whereas EcCRP bound specifically to CRP-S sites in vitro, HiCRP did not. By systematically substituting base pairs in native promoters and in the CRP-N consensus sequence, we confirmed that HiCRP is highly specific for the perfect core sequence T 4G 5T 6G 7A 8 and is more selective than EcCRP at other positions in CRP sites. Even though converting C 6 → T 6 greatly enhanced HiCRP binding to a CRP-S site, this had the unexpected effect of nearly abolishing promoter activity. A + T-rich sequences upstream of CRP-S sites were also found to be required for promoter activation, raising the possibility that Sxy binds these A + T sequences to simultaneously enable CRP–DNA binding and assist in RNA polymerase recruitment.

Evidence for interaction between the 2a polymerase protein and the 3a movement protein of Cucumber mosaic virus

The genome of Cucumber mosaic virus consists of three single-stranded RNA molecules, RNAs 1, 2 and 3. RNAs 1 and 2 encode the 1a and 2a proteins, respectively, which are necessary for replication of the viral genome and have been implicated in movement of the viral RNAs in plants. The 3a movement protein (MP), encoded by RNA 3, is essential for transferring the RNA genomes from infected cells to adjacent cells across the plasmodesmata. Far-Western analysis demonstrated that bacterially expressed 2a polymerase protein directly interacted with the MP. Interaction was confirmed in a yeast two-hybrid assay, and co-immunoprecipitation analysis showed that the MP interacted only with the 2a polymerase protein. A yeast three-hybrid assay showed that the 1a-2a protein interaction relevant for replicase complex formation was not affected by the MP. Although the MP has no affinity for the 1a protein, it interacted indirectly with the 1a protein via the 2a polymerase protein. These results suggest that the replicase complex may be involved in movement through its interaction with the MP.

Indirect readout of DNA sequence at the primary-kink site in the CAP-DNA complex: alteration of DNA binding specificity through alteration of DNA kinking

The catabolite activator protein (CAP) sharply bends DNA in the CAP-DNA complex, introducing a DNA kink, with a roll angle of ∼40° and a twist angle of ∼20°, between positions 6 and 7 of the DNA half-site, 5′-A 1A 2A 3T 4G 5T 6G 7A 8T 9C 10T 11-3′ (“primary kink”). CAP recognizes the base-pair immediately 5′ to the primary-kink site, T:A 6, through an “indirect-readout” mechanism involving sequence effects on the energetics of primary-kink formation. CAP recognizes the base-pair immediately 3′ to the primary-kink site, G:C 7, through a “direct-readout” mechanism involving formation of a hydrogen bond between Glu181 of CAP and G:C 7. Here, we report that substitution of the carboxylate side-chain of Glu181 of CAP by the one-methylene-group-shorter carboxylate side-chain of Asp changes DNA binding specificity at position 6 of the DNA half site, changing specificity for T:A 6 to specificity for C:G 6, and we report a crystallographic analysis defining the structural basis of the change in specificity. The Glu181→Asp substitution eliminates the primary kink and thus eliminates indirect-readout-based specificity for T:A 6. The Glu181→Asp substitution does not eliminate hydrogen-bond formation with G:C 7, and thus does not eliminate direct-readout-based specificity for G:C 7.

Indirect readout of DNA sequence at the primary-kink site in the CAP-DNA complex: DNA binding specificity based on energetics of DNA kinking

The catabolite activator protein (CAP) makes no direct contact with the consensus base-pair T:A at position 6 of the DNA half-site 5′-A 1A 2A 3T 4G 5T 6G 7A 8T 9C 10T 11-3′ but, nevertheless, exhibits strong specificity for T:A at position 6. Binding of CAP results in formation of a sharp DNA kink, with a roll angle of ∼40° and a twist angle of ∼20°, between positions 6 and 7 of the DNA half-site. The consensus base-pair T:A at position 6 and the consensus base-pair G:C at position 7 form a T:A/G:C step, which is known to be associated with DNA flexibility. It has been proposed that specificity for T:A at position 6 is a consequence of formation of the DNA kink between positions 6 and 7, and of effects of the T:A 6/G:C 7 step on the geometry of DNA kinking, or the energetics of DNA kinking. In this work, we determine crystallographic structures of CAP-DNA complexes having the consensus base-pair T:A at position 6 or the non-consensus base-pair C:G at position 6. We show that complexes containing T:A or C:G at position 6 exhibit similar overall DNA bend angles and local geometries of DNA kinking. We infer that indirect readout in this system does not involve differences in the geometry of DNA kinking but, rather, solely differences in the energetics of DNA kinking. We further infer that the main determinant of DNA conformation in this system is protein-DNA interaction, and not DNA sequence.

Two unusual new dinoflagellate cyst genera from the Bunde Borehole, Maastrichtian type area, southern Netherlands

Maastrichtian and Danian deposits from the Bunde Borehole in the Maastrichtian type area contain the morphologically unusual dinoflagellate species Spumadinium felderorum gen. et sp. nov. and Lasagniella herngreenii gen. et sp. nov., both of which have archeopyles formed by the loss of several paraplates. In S. felderorum the paraplates forming the operculum or opercular pieces appear to be the third and fourth precingulars (3″–4″) plus the first and second anterior intercalaries (1a–2a). This suggests that Spumadinium, although having a wall resembling some cribroperidinioids, is a cladopyxiinean. L. herngreenii is unique in having up to eight wall layers, separated and supported by buttresses. The archeopyle is also a combination type but formed by loss of one apical (3′), three anterior intercalary (1a–3a) and three precingular (3″–5″) paraplates. Thus, Lasagniella is assignable to the Peridiniales. The distinctive morphology and restricted ranges of the two genera make them useful stratigraphic markers for the Upper Maastrichtian–Danian.

ACMANTHINA: A NEW GENUS OF TORTRICID MOTHS (LEPIDOPTERA: TORTRICIDAE: EULIINI) FROM CHILE AND ARGENTINA

Acamanthina, new genus, is described and illustrated from Chile and Argentina, and includes two species: A. acmanthes (Meyrick, 1931) (type species), new combination, and A. albipuncta, new species. Acmanthina can be distinguished from all other genera in Euliini by two external and one genitalia feature of the males: the absence of elongate scaling in the basal portion of the hindwing along veins 1A 2A and CuP (present in the female), the possession of a fascicle of 17–20 extremely long sex scales (=hairpencil) concealed in a deep fold along the basal three-fifths of hindwing vein CuP, and the deep mesal excavation of the juxta. The new genus appears to be most closely related to Haemateulia Razowski.

Aqueous Organometallic Chemistry of the Electrophilic [(η-C5(CH3)5)Ru(NO)]2+ Fragment

Treatment of Cp‘Ru(NO)(CH3)2 with 2 equiv of HOSO2CF3 (HOTf) leads to the formation of the ditriflate complexes Cp‘Ru(NO)(OTf)2 (1a,b) (Cp‘ = η-C5(CH3)5, Cp* (1a), η-C5(CH3)4(CH2CH3), Cp† (1b)). The complex salts [Cp†Ru(NO)(OTf)(OH2)][OTf] (2b) and [Cp†Ru(NO)(OH2)2][OTf]2 (3b) can be isolated from the hydration of 1b. The structures of 1b, 2b, and 3b are determined by single-crystal X-ray diffraction methods. In 0.1 M H2O/CH2Cl2 the equilibria 1a 2a+ + OTf- 3a2+ + 2OTf- exist, with 1a being the predominant complex and ΔH1 = −15(3) kcal/mol and ΔS1 = −60(30) eu (for K1) and ΔH2 = −9(1) kcal/mol and ΔS2 = −40(25) eu (for K2). For comparison, the equilibria 1a [Cp*Ru(NO)(OTf)(THF)]+ + OTf- [Cp*Ru(NO)(THF)2]2+ + 2OTf- exist in neat THF with ΔH1 = −4.5(3) kcal/mol and ΔS1 = −30(10) eu (for K1) and ΔH2 = −4.1(1) kcal/mol and ΔS2 = −20(10) eu (for K2). The anion exchange equilibria in CH2Cl2 1a + 2Cl- [Cp*Ru(NO)(OTf)(Cl) + OTf- + Cl- [Cp*Ru(NO)Cl2] + 2OTf- has ΔH1 = −9(1) kcal/mol and ΔS1 = −30(10) eu (for K1) and ΔH2 = −11(1) kcal/mol and ΔS2 = −30(10) eu (for K2). While loss of the OTf- ligands is exothermic, the displacement of OTf- from the coordination sphere carries a significant entropy cost due to the formation of ions in a more-ordered solvent cage. Complex salts 1a,b dissolve in water to give acidic red-orange solutions containing an equilibrium mixture of the diaqua complex cations [Cp‘Ru(NO)(OH2)2]2+ (3a2+, pKa = 2.7; 3b2+) and the dinuclear cations [Cp‘Ru(NO)(μ-OH)]22+ (4a2+, pKa = 5.5; 4b2+). The cations 4a2+ and 4b2+ exist as a mixture of cis (major) and trans (minor) isomers; X-ray results show 4b2+ to be cis in the solid state. Crossover between 4a2+ and 4b2+ to give the mixed Cp*/Cp† dimer 4c2+ occurs readily under acidic conditions but not under basic conditions. The pH dependence together with kinetic and van't Hoff analyses support the process 2 3a2+ ⇄ 4a2+ + 2H3O+. The ∠Ru−N−O values of ca. 160°, correspondingly low νNO values in the Nujol mull IR spectra, and relatively short Ru−O bonds show the H2O and OH- ligands to be significant π-donors to the electrophilic Ru center. Dissolution of 4a,b in basic D2O causes complete deuteration of the ring CH3 groups but no deuteration of the Cp†-CH2CH3 group; the CD3 groups are easily exchanged to CH3 by exposure to basic H2O conditions. Chloride substitution by H2O occurs when Cp‘Ru(NO)Cl2 is dissolved in water, giving an equilibrium mixture of undissociated [Cp‘Ru(NO)Cl2]aq together with the [Cp‘Ru(NO)(Cl)(OH2)]+ and [Cp‘Ru(NO)(μ-OH)]22+ ions. H/D exchange on the Cp‘ ring CH3 groups also occurs slowly when Cp‘Ru(NO)Cl2 is dissolved in D2O but not when dissolved in a D2O/DCl mixture. The present work suggests that Cp‘-ring slippage and the reversible release of H+/D+ is facilitated by the π-donor ability of the H2O and OH- ligands.

Biochemical and Genetic Analyses of the Interaction between the Helicase-like and Polymerase-like Proteins of the Brome Mosaic Virus

Replication of the three positive-strand genomic RNAs of brome mosaic virus requires the activities of the helicase-like 1a and the polymerase-like 2a proteins. One hundred fifteen amino acids of the 2a N-terminus and the 1a helicase-like region of over 50 kDa are both necessary and sufficient for 1a–2a interaction. Requirement of the large size of the 1a helicase-like domain suggests that higher order structures might be necessary for the protein's interaction with 2a. To explore the structural properties of 1a, we used limited proteolysis ofin vitro-translated 1a protein. Treatment of 1a and its deletion derivatives with papain or trypsin revealed that the C-terminal helicase-like segment of approximately 50–60 kDa is highly resistant under our assay conditions to proteolysis, while the N-terminus is rapidly degraded. All tested mutations in the helicase-like region that renders this region protease-sensitive have previously been found to be defective for RNA replicationin vivo.To complement thein vitrostudies, we examined the interaction of the 1a helicase-like domain and the 2a N-terminus in yeast using the two-hybrid system. Mutations previously known to disrupt 1a–2a interaction also prevented interaction in yeast. Furthermore, results from two-hybrid analysis suggest that the structural domain mappedin vitrois important for 1a–2a interaction. Finally, we found that the helicase-like proteins of three other tripartite RNA viruses also contain equivalently located protease-resistant domains.

Displacement of aromatic nitro groups by anionic sulfur nucleophiles: reactivity of aryl disulfide and thiolate ions towards dinitrobenzenes in N,N-dimethylacetamide

Nucleophilic substitutions of 1,2- and 1,4-dinitrobenzenes (oDNB and pDNB) by thiolates ArS–(a) and aryl disulfide ions ArS2–(b)[Ar = 4-methylphenyl (1), 4-fluorophenyl (2)] have been studied in dilute solutions by spectroelectrochemistry in N,N-dimethylacetamide. Compounds 1b–2b are the predominant reactive species in ArSx–(x= 2) solutions when sulfur is added to electrogenerated thiolates 1a–2a. In all cases the addition of dinitrobenzenes led to the fast displacement of one of the NO2 groups at room temperature. With thiolate ions, the stoichiometric formation of the expected unsymmetrical diaryl monosulfides NO2C6H4SAr was observed. Aryl disulfide ions reacted in two successive steps: (i) SNAr substitution affording NO2C6H4S2Ar; (ii) displacement of NO2C6H4Sx– ions (x= 1,2) by S-nucleophilic attack of the S–S bond or a concurrent redox process. Reactions between 4-CH3C6H4Sx–(x= 2) ions and oDNB or pDNB which were performed on the preparative scale confirmed the formation of mixtures of Ar2S2 and Ar2S3 symmetrical polysulfides.

Cutaneous manifestations of early human immunodeficiency virus exposure

After demonstrating antibodies to the human immunodeficiency virus (HIV), twq hundred patients were interviewed and given a complete cutaneous and mucous membrane examination. By means of the Walter Reed Staging Classification System for HIV infection, 155 patients were classified as having Walter Reed stage 1A–2A (WR1A–WR2A) infection. The prevalence of seborrheic dermatitis in this group was 36%. There were no other significant cutaneous findings in the WR1A–WR2A patient population.