bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient Class I Major Histocompatibility Complex Down-Regulation by Simian Immunodeficiency Virus Nef Is Associated with a Strong Selective Advantage in Infected Rhesus Macaques
Authors: Münch Jan , Stolte Nicole , Fuchs Dietmar , Stahl-Hennig Christiane , Kirchhoff Frank
Published: July 2002

Substitution of Y223F disrupts the ability of simian immunodeficiency virus (SIV) Nef to down-modulate major histocompatibility complex (MHC) class I from the cell surface but has no effect on other Nef functions, such as down-regulation of CD4, CD28, and CD3 cell surface expression or stimulation of viral replication and enhancement of virion infectivity. Inoculation of three rhesus macaques with the SIVmac239 Y223F-Nef variant revealed that this point mutation consistently reverts and that Nef activity in MHC class I down-modulation is fully restored within 4 weeks after infection. Our results demonstrate a strong selective pressure for a tyrosine at amino acid position 223 in SIV Nef, and they constitute evidence that Nef-mediated MHC class I down-regulation provides a selective advantage for viral replication in vivo.
A Phosphatidylinositol 3-Kinase Docking Site in the Cytoplasmic Tail of the Jaagsiekte Sheep Retrovirus Transmembrane Protein Is Essential for Envelope-Induced Transformation of NIH 3T3 Cells
Authors: Palmarini Massimo , Maeda Naoyoshi , Murgia Claudio , De-Fraja Claudio , Hofacre Andrew , Fan Hung
Published: July 2002

Jaagsiekte sheep retrovirus (JSRV) is the causative agent of a transmissible lung cancer of sheep known as ovine pulmonary carcinoma. Recently, we have found that the expression of the JSRV envelope (Env) is sufficient to transform mouse NIH 3T3 cells in classical transformation assays. To further investigate the mechanisms of JSRV oncogenesis, we generated a series of envelope chimeras between JSRV and the JSRV-related endogenous retroviruses of sheep (enJSRVs) and assessed them in transformation assays. Chimeras containing the exogenous JSRV SU region and the enJSRV TM region were unable to transform NIH 3T3 cells. Additional chimeras containing only the carboxy-terminal portion of TM (a region that we previously identified as VR3) of the endogenous envelope with SU and the remaining portion of TM from the exogenous JSRV were also unable to transform NIH 3T3 cells. The VR3 region includes the putative membrane-spanning region and cytoplasmic tail of the JSRV TM glycoprotein; this suggested that the cytoplasmic tail of the JSRV Env mediates transformation, possibly via a cell signaling mechanism. Mutations Y590 and M593 in the cytoplasmic tail of the JSRV envelope were sufficient to inhibit the transforming abilities of these constructs. Y590 and M593 are part of a Y-X-X-M motif that is recognized by the phosphatidylinositol 3-kinase (PI-3K). PI-3K initiates a cell signaling pathway that inhibits apoptosis and is required for a number of mitogens during the G
1
-to-S-phase transition of the cell cycle. PI-3K activates Akt by phosphorylation of threonine 308 and serine 473. We detected by Western blot analysis phosphorylated Akt in serum-starved MP1 cells (NIH 3T3 cells transformed by JSRV) but not in the parental NIH 3T3 cells. These data indicate that the cytoplasmic tail of the JSRV TM is necessary for cell transformation and suggest a new mechanism of retroviral transformation. In addition, the ability to dissociate the function of the JSRV envelope to mediate viral entry from its transforming capacity has direct relevance for the design of JSRV-based vectors that target the differentiated epithelial cells of the lungs.
Genetic Clustering of Hepatitis C Virus Strains and Severity of Recurrent Hepatitis after Liver Transplantation
Authors: Gigou Michèle , Roque-Afonso Anne Marie , Falissard Bruno , Penin François , Dussaix Elisabeth , Féray Cyrille
Published: July 2002

The influence of viral factors on the severity of hepatitis C virus (HCV)-related liver disease is controversial. We studied 68 liver transplant patients with recurrent hepatitis C, of whom 53 were infected by genotype 1 strains. Relationships between core sequences, serum HCV RNA levels, and fibrosis scores for each patient were analyzed in pairwise fashion 5 years after transplantation. We used Mantel's test, a matrix correlation method, to evaluate the correspondence between measured genetic distances and observed phenotypic differences. No clear relationship was found when all 68 patients were analyzed. In contrast, when the 53 patients infected by genotype 1 strains were analyzed, a strong positive relationship was found between genetic distance and differences in 5-year fibrosis scores (
P
= 0.001) and differences in virus load (
P
= 0.009). In other words, the smaller the genetic distance between two patients' viral core sequences, the smaller the difference between the two patients' fibrosis scores and viral replication levels. No relationship was found between genetic distance and differences in age, sex, or immunosuppression. In multivariate analysis, the degree of fibrosis was negatively related to the virus load (
r
= −0.68;
P
= 0.003). In the particular setting of liver transplantation, and among strains with closely related phylogenetic backgrounds (genotype 1), this study points to a correlation between the HCV genetic sequence and the variability of disease expression.
Murine Leukemia Virus Proviral Insertions between the N-
ras
and
unr
Genes in B-Cell Lymphoma DNA Affect the Expression of N-
ras
Only
Authors: Martı́n-Hernández Javier , Sørensen Annette Balle , Pedersen Finn Skou
Published: July 2002

Akv1-99, a variant of Akv murine leukemia virus, induces B-cell lymphomas with nearly 100% incidence and a mean latency period of 12 months after injection into newborn NMRI mice. PCR amplification and sequence analyses of DNA flanking integrated proviruses revealed proviral insertion into the N-
ras/unr
(upstream of N-
ras
) locus in 2 out of 13 B-cell lymphomas, both of which appeared clonal by Southern blotting analysis. These two tumors showed increased expression levels of N-
ras
by Northern blotting, as did a third tumor shown by reverse transcriptase PCR to have a nonclonal provirus integration located in the same area. However, no significant changes in expression were observed when using a specific probe for the
unr
gene. All proviruses were integrated in the same transcriptional orientation as
unr
and N-
ras
genes. By promoter insertion, the two Akv1-99 proviruses integrated between exon −1 and exon 1 of N-
ras
gave rise to two different spliced products, whereas the provirus integrated into
unr
used only an exon skipping pattern. The absence of mutations of the N-
ras
codons 12, 13, 18, and 61 suggests that activation of the proto-oncogene is exclusively due to overexpression by retroviral promoter insertion, and furthermore, Northern blot analyses indicate that the expression of
unr
is unaffected by N-
ras
overexpression even in the case where the
unr
gene itself is the target of proviral insertion. Thus, altogether our findings indicate that overexpression of N-
ras
plays a role in development of murine leukemia virus-induced B-cell lymphomas, leaving the expression of the tightly linked
unr
gene unaltered.
Herpes Simplex Virus Type 1 2-Kilobase Latency-Associated Transcript Intron Associates with Ribosomal Proteins and Splicing Factors
Authors: Ahmed Maryam , Fraser Nigel W.
Published: July 2002

During latency of herpes simplex virus type 1 in sensory neurons, the transcription of viral genes is restricted to the latency-associated transcripts (LATs). The stable 2-kb LAT intron has been characterized previously and has been shown to accumulate to high levels in the nuclei of infected neurons. However, in productively infected tissue culture cells, this unique intron is also found in the cytoplasm. Although deletion mutant analysis has suggested that the region of the gene from which the intron is spliced plays a role in maintenance of latency or in reactivation from latency, no well-defined function has been ascribed specifically to the 2-kb LAT intron. Nevertheless, previous work has shown that it associates with 50S particles in the cytoplasm of acutely infected cells. Our studies tested the ability of the 2-kb LAT to dissociate from cytoplasmic protein complexes under various salt conditions. Results indicated that this association, which had been speculated to be mRNA-like, is actually more similar to the affinity of rRNAs for translational complexes. Furthermore, by immunoprecipitation analysis, we demonstrate that the 2-kb LAT associates with ribosomal as well as with splicing complexes in infected cells. Our results suggest that the 2-kb LAT is processed similarly to mRNAs in the nuclei of infected cells. However, in the cytoplasm, the 2-kb LAT may play a structural role in the ribosomal complex, similar to that of the cellular rRNAs, and therefore affect the functioning of the translational machinery.
Latently Expressed Human Herpesvirus 8-Encoded Interferon Regulatory Factor 2 Inhibits Double-Stranded RNA-Activated Protein Kinase
Authors: Burýšek Ladislav , Pitha Paula M.
Published: July 2002

Human herpesvirus 8 (HHV-8; Kaposi's sarcoma herpesvirus) encodes four open reading frames with homology to cellular proteins of interferon regulatory factor (IRF) family. Three of them, viral IRF-1 (vIRF-1), vIRF-2, and vIRF-3, have been cloned and found, when overexpressed, to down-regulate the transcriptional activity of interferon type I gene promoters in infected cells by interfering with the transactivating activity of cellular IRFs. In this study, we have further characterized vIRF-2 and shown that it is a nuclear protein which is constitutively expressed in HHV-8-positive pleural effusion lymphoma cell lines. Nuclear localization of vIRF-2 was confirmed by in situ detection of ectopically expressed enhanced green fluorescent protein/vIRF-2 fusion protein. We found that the expression of vIRF-2 in HEK293 cells inhibited the antiviral effect of interferon and rescued translation of vesicular stomatitis virus mRNA from interferon-induced translational block. To provide insight into the mechanism of this effect we have demonstrated that vIRF-2 physically interacts with PKR consequently inhibiting autophosphorylation of double-stranded RNA-activated protein kinase (PKR) and blocking phosphorylation of PKR substrates histone 2A and eukaryotic translation initiation factor 2α. These results suggest that the latently expressed vIRF-2 has a role in viral mimicry which targets the activity of interferon-induced PKR kinase. By inhibiting the kinase activity of PKR and consequent down-modulation of protein synthesis, HHV-8 has evolved a mechanism by which it can overcome the interferon-mediated antiviral effect. Thus, the anti-interferon functions of vIRF-2 may contribute to the establishment of a chronic or latent infection.
Activators of the Epstein-Barr Virus Lytic Program Concomitantly Induce Apoptosis, but Lytic Gene Expression Protects from Cell Death
Authors: Inman Gareth J. , Binné Ulrich K. , Parker Gillian A. , Farrell Paul J. , Allday Martin J.
Published: July 2002

Expression of the lytic cycle genes of Epstain-Barr virus (EBV) is induced in type I Burkitt's lymphoma-derived cells by treatment with phorbol esters (e.g., phorbol myristate acetate [PMA]), anti-immunoglobulin, or the cytokine transforming growth factor β (TGF-β). Concomitantly, all these agents induce apoptosis as judged by a sub-G1fluorescence-activated cell sorter (FACS) profile, proteolytic cleavage of poly(ADP-ribose) polymerase (PARP) and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. However, caspase activation is not required for induction of the lytic cycle since the latter is not blocked by the caspase inhibitor ZVAD. Furthermore, not all agents that induce apoptosis in these cultures (for example, cisplatin and ceramide) induce the EBV lytic programme. Although it is closely associated with the lytic cycle, apoptosis is neither necessary nor sufficient for its activation. Multiparameter FACS analysis of cultures treated with PMA, anti-Ig, or TGF-β revealed BZLF1-expressing cells distributed in different phases of the cell cycle according to which inducer was used. However, BZLF1-positive cells did not appear to undergo apoptosis and accumulate with a sub-G1DNA content, irrespective of the inducer used. This result, which suggests that lytic gene expression is protective, was confirmed and extended by immunofluorescence staining doubled with TUNEL analysis. BZLF1- and also gp350-expressing cells were almost always shown to be negative for TUNEL staining. Similar experiments using EBV-positive and -negative subclones of Akata BL cells carrying an episomal BZLF1 reporter plasmid confirmed that protection from apoptosis was associated with the presence of the EBV genome. Finally, treatment with phosphonoacetic acid or acyclovir prior to induction with PMA, anti-Ig, or TGF-β blocked the protective effect in Mutu-I cells. These data suggest that a late gene product(s) may be particularly important for protection against caspase activity and cell death.
Immunization with Chaperone-Peptide Complex Induces Low-Avidity Cytotoxic T Lymphocytes Providing Transient Protection against Herpes Simplex Virus Infection
Authors: Kumaraguru Udayasankar , Gierynska Malgorzata , Norman Shanna , Bruce Barry D. , Rouse Barry T.
Published: July 2002

Heat shock proteins loaded with viral peptides were shown to induce a CD8
+
T cell response and confer protective immunity against challenge with herpes simplex virus (HSV). The delivery system consisted of recombinant human hsp70 coupled to the peptide SSIEFARL, which is the immunodominant peptide epitope, recognized by HSV specific T cells in C57BL/6 mice. Immunization resulted in CD8
+
T-cell responses, measured by peptide-specific tetramers and peptide-induced intracellular gamma interferon expression and cytotoxicity, similar to responses resulting from immunization with a recombinant vaccinia virus that expressed SSIEFARL as a minigene (VvgB) and UV-inactivated HSV. However, the durability of the hsp70-SSIEFARL response was less than that resulting from VvgB and HSV immunization and in addition the CD8
+
T-cell responses in the memory phase were functionally less effective. Mice challenged soon after immunization showed excellent immunity, but by 90 days postimmunization this had waned to be significantly less than the level of immunity in both VvgB- and HSV-immunized mice.
Comprehensive Screening for Human Immunodeficiency Virus Type 1 Subtype-Specific CD8 Cytotoxic T Lymphocytes and Definition of Degenerate Epitopes Restricted by HLA-A0207 and -CW0304 Alleles
Authors: Currier Jeffrey R. , deSouza Mark , Chanbancherd Penprapa , Bernstein Wendy , Birx Deborah L. , Cox Josephine H.
Published: July 2002

For this report, the rapid identification and characterization of human immunodeficiency virus type 1 (HIV-1)-derived broadly cross-subtype-reactive CD8 cytotoxic T lymphocyte (CTL) epitopes were performed. Using a gamma interferon (IFN-γ) Elispot assay-based approach and a panel of recombinant vaccinia viruses expressinggag,env,pol, andnefgenes representing the seven most predominant subtypes and one circulating recombinant form of HIV-1, the subtype specificity and cross-subtype reactivity of a CD8 response were directly measured from circulating peripheral blood mononuclear cells (PBMC). Enhanced sensitivity of detection of CD8 responses from cryopreserved PBMC was achieved using autologous vaccinia virus-infected B-lymphoblastoid cell lines as supplemental antigen-presenting cells. Of eleven subjects studied, six exhibited broadly cross-subtype-reactive CD8-mediated IFN-γ production (at least seven of eight subtypes recognized) to at least one major gene product from HIV-1. Screening of subjects showing broadly cross-subtype-specific responses in the vaccinia virus-based enzyme-linked immunospot (Elispot) assay using a panel of overlapping peptides resulted in the identification of cross-subtype responses down to the 20-mer peptide level in less than 3 days. Three subjects showed broad cross-subtype reactivity in both the IFN-γ Elispot assay and the standard chromium release cytotoxicity assay. Fine mapping and HLA restriction analysis of the response from three subjects demonstrated that this technique can be used to define epitopes restricted by HLA-A, -B, and -C alleles. In addition, the ability of all three epitopes to be processed from multiple subtypes of their parent proteins and presented in the context of HLA class I molecules following de novo synthesis is shown. While all three minimal epitopes mapped here had previously been defined as HIV-1 epitopes, two are shown to have novel HLA restriction alleles and therefore exhibit degenerate HLA binding capacity. These findings provide biological validation of HLA supertypes in HIV-1 CTL recognition and support earlier studies of cross-subtype CTL responses during HIV-1 infection.
A Nucleotide Substitution in the tRNA
Lys
Primer Binding Site Dramatically Increases Replication of Recombinant Simian Immunodeficiency Virus Containing a Human Immunodeficiency Virus Type 1 Reverse Transcriptase
Authors: Soderberg Kelly , Denekamp Lynn , Nikiforow Sarah , Sautter Karen , Desrosiers Ronald C. , Alexander Louis
Published: July 2002

A recombinant simian immunodeficiency virus (SIV) derived from strain 239 (SIVmac239) with reverse transcriptase (RT) sequences from human immunodeficiency virus type 1 (HIV-1) strain HXB2 was severely impaired for replication. Detectable p27
Gag
levels were not observed until day 65 and peak p27
Gag
levels were not reached until day 75 after transfection of CEMx174 cells with the recombinant DNA. Sequences from the latter time point did not contain amino acid substitutions in HIV-1 RT; however, a single nucleotide substitution (thymine to cytosine) was found at position eight of the SIV primer binding site. We engineered an RT/SHIV genome with the thymine-to-cytosine substitution, called RT/SHIV/TC, and observed dramatically faster replication kinetics than were observed with the parental RT/SHIV from which this variant was derived. RT/SHIV/TC provides an improved system for study of the impact of drug resistance mutations in HIV-1 RT in a relevant animal model.
Diarrhea-Inducing Activity of Avian Rotavirus NSP4 Glycoproteins, Which Differ Greatly from Mammalian Rotavirus NSP4 Glycoproteins in Deduced Amino Acid Sequence, in Suckling Mice
Authors: Mori Yoshio , Borgan Mohammed Ali , Ito Naoto , Sugiyama Makoto , Minamoto Nobuyuki
Published: July 2002

Avian rotavirus NSP4 glycoproteins expressed in
Escherichia coli
acted as enterotoxins in suckling mice, as did mammalian rotavirus NSP4 glycoproteins, despite great differences in the amino acid sequences. The enterotoxin domain of PO-13 NSP4 exists in amino acid residues 109 to 135, a region similar to that reported in SA11 NSP4.
A Mutation in the 3′ Region of the Human Immunodeficiency Virus Type 1 Reverse Transcriptase (Y318F) Associated with Nonnucleoside Reverse Transcriptase Inhibitor Resistance
Authors: Harrigan P. Richard , Salim Mahboob , Stammers David K. , Wynhoven Brian , Brumme Zabrina L. , McKenna Paula , Larder Brendan , Kemp S. D.
Published: July 2002

The Y318F substitution in the 3′ region of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) has been linked to nonnucleoside RT inhibitor (NNRTI) resistance in vitro. A systematic search of a large phenotypic-genotypic database (Virco) linked the Y318F substitution with a >10-fold decrease in NNRTI susceptibility in >85% of clinically derived isolates. There was a significant association between Y318F and use of delavirdine (
P
= 10
−11
) and nevirapine (
P
= 10
−6
) but not efavirenz (
P
= 0.3). Site-directed HIV-1 Y318F mutants in an HXB2 background displayed 42-fold-decreased susceptibility to delavirdine but <3-fold-decreased susceptibility to nevirapine or efavirenz. Combinations of Y318F with K103N, Y181C, or both resulted in decreased efavirenz susceptibility of 43-, 3.3-, and 84-fold, respectively, as well as >100- and >60-fold decreases in delavirdine and nevirapine susceptibility, respectively. These results indicate the importance of the Y318F substitution in HIV-1 drug resistance.
Human Immunodeficiency Virus Type 1-Hepatitis C Virus Coinfection: Intraindividual Comparison of Cellular Immune Responses against Two Persistent Viruses
Authors: Lauer Georg M. , Nguyen Tam N. , Day Cheryl L. , Robbins Gregory K. , Flynn Theresa , McGowan Katherine , Rosenberg Eric S. , Lucas Michaela , Klenerman Paul , Chung Raymond T. , Walker Bruce D.
Published: July 2002

Both human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) lead to chronic infection in a high percentage of persons, and an expanding epidemic of HIV-1-HCV coinfection has recently been identified. These individuals provide an opportunity for simultaneous assessment of immune responses to two viral infections associated with chronic plasma viremia. In this study we analyzed the breadth and magnitude of the CD8+- and CD4+-T-lymphocyte responses in 22 individuals infected with both HIV-1 and HCV. A CD8+-T-lymphocyte response against HIV-1 was readily detected in all subjects over a broad range of viral loads. In marked contrast, HCV-specific CD8+-T-lymphocyte responses were rarely detected, despite viral loads in plasma that were on average 1,000-fold higher. The few HCV-specific responses that were observed were relatively weak and limited in breadth. CD4-proliferative responses against HIV-1 were detected in about half of the coinfected subjects tested, but no proliferative response against any HCV protein was found in these coinfected persons. These data demonstrate a major discordance in immune responses to two persistent RNA viruses. In addition, they show a consistent and profound impairment in cellular immune responses to HCV compared to HIV-1 in HIV-1-HCV-coinfected persons.
Lymphotoxin-α- and Lymphotoxin-β-Deficient Mice Differ in Susceptibility to Scrapie: Evidence against Dendritic Cell Involvement in Neuroinvasion
Authors: Oldstone Michael B. A. , Race Richard , Thomas Diane , Lewicki Hanna , Homann Dirk , Smelt Sara , Holz Andreas , Koni Pandelakis , Lo David , Chesebro Bruce , Flavell Richard
Published: July 2002

Transmissible spongiform encephalopathy or prion diseases are fatal neurodegenerative disorders of humans and animals often initiated by oral intake of an infectious agent. Current evidence suggests that infection occurs initially in the lymphoid tissues and subsequently in the central nervous system (CNS). The identity of infected lymphoid cells remains controversial, but recent studies point to the involvement of both follicular dendritic cells (FDC) and CD11c+lymphoid dendritic cells. FDC generation and maintenance in germinal centers is dependent on lymphotoxin alpha (LT-α) and LT-β signaling components. We report here that by the oral route, LT-α −/− mice developed scrapie while LT-β −/− mice did not. Furthermore, LT-α −/− mice had a higher incidence and shorter incubation period for developing disease following inoculation than did LT-β −/− mice. Transplantation of lymphoid tissues from LT-β −/− mice, which have cervical and mesenteric lymph nodes, into LT-α −/− mice, which do not, did not alter the incidence of CNS scrapie. In other studies, a virus that is tropic for and alters functions of CD11c+cells did not alter the kinetics of neuroinvasion of scrapie. Our results suggest that neither FDC nor CD11c+cells are essential for neuroinvasion after high doses of RML scrapie. Further, it is possible that an as yet unidentified cell found more abundantly in LT-α −/− than in LT-β −/− mice may assist in the amplification of scrapie infection in the periphery and favor susceptibility to CNS disease following peripheral routes of infection.
Approximate Calculation of Pressure Drop in Laminar Flow of Generalized Newtonian Liquid Through Channel of Noncircular Cross Section
Authors: Dolejš Václav , Machač Ivan , Doleček Petr
Published: July 2002

The paper presents a modification of the equations of Rabinowitsch-Mooney type for an approximate calculation of pressure drop in laminar flow of generalized Newtonian liquid through a straight channel whose cross section forms a simple continuous area. The suitability of the suggested procedure of calculation of pressure drop is demonstrated by the comparison of calculation results with both the published and original results of numerical solution and experiments.
Second Virial Coefficient of the 2cLJ, 3cLJ and 4cLJ Molecules
Authors: Boublík Tomáš
Published: July 2002

The second virial coefficient was evaluated for the two-centre, three-centre and four-centre Lennard Jones molecules with the site site distance l ∈ (0,1) at the reduced temperatures Tr = 0.6 - 3.0. The obtained data are correlated by an expression derived originally for the Kihara non-spherical molecules; the same value of the σ-parameter is considered for the both pair potentials whereas εKihara/εncLJ and lKihara / lncLJ vary with the increasing values of lncLJ. Values of the virial coefficient of the individual ncLJ molecules agree within error bars with experimental values in the whole temperature range studied; with only slightly higher deviations also data for the single 2cLJ, 3cLJ and 4cLJ molecules for all the lncLJ values can be correlated.
Studies of the Reaction of Triaminophosphines with α,β-Unsaturated Nitriles
Authors: Hennawy Ibtisam T.
Published: July 2002

Tris(dialkylamino)phosphines IIIa and IIIb react with furfurylidenemalonitrile (Ia) and its thiophene analogue Ib to give a mixture of 1 : 1 adducts IV and V. Compounds IV have aminophosphonium dipolar ion structure, while compounds V are the ylide forms. The ratio of the products depends on the reaction conditions. Some reactions of IV and V are described.
Michael-Michael Aldol Reaction of Chalcones with Cyanoacetylurea and Cyanoacetylpiperidine
Authors: Tabba Hani D. , Yousef Nidal M. , Al-Arab Mohammad M.
Published: July 2002

Several highly substituted cyclohexane derivatives were synthesized by the one-pot condensation of chalcones and cyanoacetylurea (2 : 1) using sodium alkoxide in anhydrous alcohol at room temperature. The structure of the reaction products was established by infrared, 1H and 13C NMR spectroscopy as well as by their elemental analysis. Single crystal X-ray crystallography shows the presence of the cyclohexane moiety.
Quantitative Relationships Between Structure, Aggregation Properties and Antimicrobial Activity of Quaternary Ammonium Bolaamphiphiles
Authors: Pavlíková Magdaléna , Lacko Ivan , Devínský Ferdinand , Mlynarčík Dušan
Published: July 2002

QSAR analysis employing Kubinyi's bilinear model was applied to examine the relationship between the structure (characterized by the lengths of the terminal hydrocarbon chain, m, and of the hydrocarbon spacer chain, y), lipophilicity (characterized by the chromatographic parameter Rm and aggregation properties expressed through the critical micellar concentration cK), and antimicrobial activity (characterized by the minimum inhibition concentration, MIC) of quaternary ammonium bolaamphiphiles. The log cK = f(m) dependence was found to be linear whereas the log (1/MIC) = f(m), log (1/MIC) = f(y), log (1/MIC) = f (log cK) and log (1/MIC) = f(Rm) dependences were nonlinear. The effect of the hydrophobic terminal chains (m) and of the hydrophobic spacer chain (y) on the aggregation properties and on the biological activity of the substances was studied.
A Facile Synthesis of 6-Cyanopurine Bases
Authors: Hocek Michal , Holý Antonín
Published: July 2002

A facile method of preparation of 6-cyanopurine bases from commercially available 6-chloropurines is reported. The 6-chloropurines were selectively protected by THP-functions and the protected derivatives reacted smoothly with tetraethylammonium cyanide and DABCO to give 6-cyanopurine derivatives that were easily deprotected to afford the title compounds.
Synthesis of Some Anilides of 2-Alkyl-4-pyridinecarboxylic Acids and Their Photosynthesis-Inhibiting Activity
Authors: Miletín Miroslav , Hartl Jiří , Macháček Miloš
Published: July 2002

Homolytic alkylation of 4-pyridinecarbonitrile with radicals generated by silver nitrate catalyzed oxidative decarboxylation of alkanoic acids and subsequent alkaline hydrolysis afforded 2-alkyl-4-pyridinecarboxylic acids 2a-2e. These were converted into the halogeno-hydroxy substituted anilides 3a-3r via acyl chlorides by reaction with the respective aminophenols at 10 °C. Of the compounds tested, 5-chloro-2-hydroxyphenylamide of 2-butyl-4-pyridinecarboxylic acid 3h showed the highest effect upon oxygen evolution rate in spinach chloroplasts system. The structure-photosynthesis-inhibiting activity relationships are briefly discussed.
Electrochemical Oxidation of Probucol in Anhydrous Acetonitrile
Authors: Nesměrák Karel , Němec Ivan , Štícha Martin , Gabriel Jiří , Mirceski Valentin
Published: July 2002

Electrochemical oxidation of probucol in anhydrous acetonitrile was studied as a model of the metabolic oxidation of the substance. The study was performed by DC voltammetry, potentiostatic coulometry, cyclic voltammetry and preparative electrolysis. Probucol gives a single anodic wave E1/2 = 0.92 V. Cyclic voltammetry showes that its electrooxidation proceeds by formation of probucol radical. 2,6-Di-tert-butyl-4-(isopropylsulfanyl)phenol, 2,6-di-tert-butyl-4-sulfanylphenol, 2,6-di-tert-butyl-4-methylphenol and 2,6-di-tert-butylphenol were isolated as products of electrochemical oxidation.
Crystal Selection and Liesegang Banding in Dynamic Precipitate Systems
Authors: Panjarian Shoghag , Sultan Rabih
Published: July 2002

We report on some phenomenological properties of precipitate patterns grown in gels. The experiments span a variety of salt systems, and yield patterns ranging from Liesegang bands to exotic crystals and to a combination of both depending on the initial conditions. The obtained crystals encompass spots, crystallites and notably dendrites of fractal nature. The particle number and size observed in discrete spotted bands of a cobalt oxinate Liesegang pattern provide a direct verification of Ostwald ripening.
Synthesis of cis and trans Isomers of D-Ring Linked Bis-Steroid Pyrazines from 16α-Bromo-17-oxosteroids
Authors: Łotowski Zenon , Morzycki Jacek W. , Niewczas Izabella S. , Zdanowicz Marta
Published: July 2002

Treatment of 16α-bromo-17-oxosteroids 1 and 2 with gaseous ammonia and successive air-oxidation afforded the cis and trans isomers of D-linked bis-steroid pyrazines. Analogous reaction of 1α-bromo-4-nor-5α-cholestan-2-one (3) led to unexpected hydrolysis products.
Changes in hip and ankle range of motion and hip muscle strength in 8–11 year old novice female ballet dancers and controls: a 12 month follow up study
Authors: Bennell K L , Khan K M , Matthews B L , Singleton C
Published: July 2002

Objectives—To evaluate in a 12 month longitudinal study changes in hip and ankle range of motion and hip muscle strength in young female novice ballet dancers.

Methods—Fifty three of the original 77 (69%) female dancers aged 8–11 years and 40 of the original 49 (82%) controls returned for follow up measurements one year later. Supine right active hip external (ER) and internal (IR) rotation were measured using an inclinometer. A turnout protractor was used to assess standing active turnout range. Range of right weight bearing ankle dorsiflexion and calf muscle length were measured in a standing lunge position using an inclinometer. A manual muscle tester was used to assess right hip flexor, IR, ER, abductor and adductor strength.

Results—The mean (SD) 12 month change in hip ER did not differ between dancers (11.7 (11.3)°) and controls (8.1 (17.6)°). Dancers gained 12.5 (13.5)° hip IR which was significantly greater than controls (0.5 (13.9)°). Greater IR change was associated with improved IR strength (r= 0.34, p<0.001). Dancers increased total turnout (12.0 (16.7)°) significantly more than controls (2.2 (20.0)°). There was no significant change in ankle dorsiflexion range in either group. Dancers and controls increased in all measures of hip muscle strength (p<0.001) and dancers achieved significantly greater gains in three out of five muscle groups (all, p<0.05).

Conclusions—Total hip range of motion increased in both ballet students and controls at this young age. However, ankle dorsiflexion did not, which is probably due to this movement being blocked by bony apposition, rather than soft tissue stretch. This has implications for ballet teachers, as it has long been accepted that this movement could be improved with training. Dancers had greater increases in hip strength after 12 months compared with controls in muscles specific for ballet, suggesting that hip strength can be trained at this young age. Whether these gains are permanent requires further study.
Oestrogen, progesterone, and androgen receptors in ovarian neoplasia: correlation between immunohistochemical and biochemical receptor analyses
Authors: van Doorn Helena C , Burger Curt W , van der Valk Paul , Bonfrér Hans M G
Published: July 2002

Aim—To investigate the correlation between immunohistochemical and biochemical steroid receptor analyses by measurement of oestrogen, progesterone, and androgen receptor status in ovarian neoplasia.

Methods—Tissue samples were obtained from 27 ovarian neoplasms, including two borderline tumours. Immunohistochemical staining of the tissue slides was scored semiquantitatively, incorporating the intensity and percentage of positive staining (histoscore). Tumours with a histoscore of 10 or more were considered steroid receptor positive. The epithelial and stromal fractions of the tumours were analysed separately. To study the uniformity of receptor expression throughout a tumour, up to four samples were analysed.

Results—Immunohistochemical histoscores of the oestrogen receptor in the epithelial fractions were significantly correlated with the biochemical oestrogen receptor values (r= 0.408). Androgen receptor status in the epithelial fraction was correlated with that in the stromal fraction (r= 0.741), while androgen receptor histoscores in the epithelial fraction correlated with the biochemical assay values (r= 0.463). On biochemical analysis, 17 of the 27 ovarian tumours were oestrogen receptor positive and seven were progesterone receptor positive. On immunohistochemical analysis, eight tumours were oestrogen receptor positive and two were progesterone receptor positive. Biochemical analysis showed that 14 of the 26 tumours were slightly androgen receptor positive (10–50 fmol/mg protein), while all the others were negative. On immunohistochemical analysis, seven of the 26 tumours were androgen receptor positive. When two or more specimens from one tumour were analysed, marked differences in steroid status were found, especially in progesterone receptor and androgen receptor expression. Some parts of a tumour were steroid receptor positive, while other parts were negative owing to heterogeneity of expression.

Conclusions—Immunohistochemical and biochemical analysis of steroid receptors in ovarian tumours correlated weakly or not at all. Heterogeneity of expression within a tumour and the presence of progesterone and androgen receptors in the stromal fraction partly accounted for this observation. Biochemical and immunohistochemical androgen receptor status was much lower than in previous reports.
Wet mount microscopy reflects functional vaginal lactobacillary flora better than Gram stain
Authors: Donders Gilbert G G , Vereecken Annie , Dekeersmaecker Alfons , Van Bulck Ben , Spitz Bernard
Published: July 2002

Aim—The status of vaginal lactobacillary flora, an indicator of possible genital infection and pregnancy complications, can be assessed on wet mount or Gram stained specimens. The former is quick, the latter more routine. The accuracy of the two preparative techniques to detect normal vaginal lactobacillary microflora was compared for 646 patients. The effect of delay in transport medium before Gram staining was also investigated.

Methods—Patients presented with infectious vaginitis or for a routine prenatal visit. After placement of a speculum, duplicate smears were taken from the upper vaginal vault and examined fresh or after Gram staining. Lactobacillary grades from both methods were compared with lactate concentration in vaginal rinses. In a subgroup of 238 patients, Gram staining was performed both on fresh smears and those that had been transported in Stuart's growth medium.

Results—Higher lactobacillary grades (more disrupted flora) were diagnosed 2.9 times more frequently on Gram stained specimens than on wet mounts (p < 0.0001), a difference even more pronounced after transport in Stuart's medium (relative risk, 4.2; p < 0.0001). Lactobacillary grades assessed on wet mounts correlated better with vaginal lactate concentration than those assessed on Gram stains.

Conclusions—Easier recognition of lactobacillary morphotypes on wet mounts than on Gram stains might result from the loss of lactobacilli by the process of fixation or Gram staining. Wet mount microscopy of vaginal smears for assessment of lactobacillary grades, rather than Gram staining, is strongly recommended.
To give or sell human gametes - the interplay between pragmatics, policy and ethics
Authors: Daniels K R
Published: July 2002

The ever-growing acceptance and use of assisted human reproduction techniques has caused demand for “donated” sperm and eggs to outstrip supply. Medical professionals and others argue that monetary reward is the only way to recruit sufficient numbers of “donors”. Is this a clash between pragmatics and policy/ethics? Where monetary payments are the norm, alternative recruitment strategies used successfully elsewhere may not have been considered, nor the negative consequences of commercialism on all participants thought through. Considerations leading some countries to ban the buying and selling of sperm, eggs and embryos are outlined and a case made that the collective welfare of all involved parties be the primary consideration in this, at times heated, debate.
The practice of clinical medicine as an art and as a science
Authors: Saunders John
Published: July 2002

The practice of modern medicine is the application of science, the ideal of which has the objective of value-neutral truth. The reality is different: practice varies widely between and within national medical communities. Neither evidence from randomised controlled trials nor observational methods can dictate action in particular circumstances. Their conclusions are applied by value judgments that may be impossible to specify in “focal particulars”. Herein lies the art which is integral to the practice of medicine as applied science.
Occupational health research priorities in Malaysia: a Delphi study
Authors: Sadhra S , Beach J R , Aw T-C , Sheikh-Ahmed K
Published: July 2002

OBJECTIVES

As part of a consultancy project on occupational health, the Delphi method was used to identify research priorities in occupational health in Malaysia.

METHODS

Participation was sought from government ministries, industry, and professional organisations, and university departments with an interest in occupational and public health. Two rounds of questionnaires resulted in a final list of priorities, with noticeable differences between participants depending on whether they worked in industry or were from government organisations.

RESULTS

The participation rate of 71% (55 of 78) was obtained for the first questionnaire and 76% (72 of 95) for the second questionnaire. The participants identified occupational health problems for specific groups and industries as the top research priority area (ranked as top priority by 25% of participants). Ministry of Health participants placed emphasis on healthcare workers (52% ranking it as top priority), whereas those from industry identified construction and plantation workers as groups, which should be accorded the highest priority. Evaluation of research and services was given a low priority.

CONCLUSIONS

The priorities for occupational health determined with the Delphi approach showed differences between Malaysia, a developing country, and findings from similar European studies. This may be expected, as differences exist in stages of economic development, types of industries, occupational activities, and cultural attitudes to occupational health and safety. Chemical poisonings and workplace accidents were accorded a high priority. By contrast with findings from western countries, workplace psychosocial problems and musculoskeletal injuries were deemed less important. There also seemed to be greater emphasis on adopting interventions for identified problems based on experience in other countries rather than the need to evaluate local occupational health provisions.
Parkinsonism and occupational exposure to pesticides
Authors: Engel L S , Checkoway H , Keifer M C , Seixas N S , Longstreth W T , Scott K C , Hudnell K , Anger W K , Camicioli R
Published: July 2002

OBJECTIVE

To examine the risk of parkinsonism related to lifetime occupational exposure to pesticides among a cohort of men, mostly orchardists, in Washington State.

METHODS

All 310 subjects in this study had previously participated in a cohort study of men occupationally exposed to pesticides. Subjects were given a structured neurological examination and completed a self administered questionnaire which elicited detailed information on pesticide (insecticide, herbicide, and fungicide) use throughout their working careers. Demographic characteristics were also sought. Subjects had a mean age of 69.6 years (range 49–96, SD 8.1). There were 238 (76.8%) subjects who reported some occupational exposure to pesticides, whereas 72 (23.2%) reported none. Parkinsonism was defined by the presence of two or more of rest tremor, rigidity, bradykinesia, and impairment of postural reflexes in subjects not on antiparkinsonian medication, or the presence of at least one sign if they were on such medication. Parkinson's disease was not studied explicitly because of the difficulty in distinguishing it from other parkinsonian syndromes. A generalised linear model was used to estimate prevalence ratios (PRs) for parkinsonism relative to history of farming, pesticide use, and use of well water.

RESULTS

A PR of 2.0 (95% confidence interval (95% CI) 1.0 to 4.2) was found for subjects in the highest tertile of years of exposure to pesticides; a similarly increased, non-significant, PR was found for the middle tertile (1.9 (95% CI 0.9 to 4.0)), although a trend test did not show a significant exposure-response relation. No increased risks were found associated with specific pesticides or pesticide classes, nor with a history of farming or use of well water.

CONCLUSION

Parkinsonism may be associated with long term occupational exposure to pesticides, although no associations with specific pesticides could be detected. This finding is consistent with most of the publications on this topic.
Non-malignant mortality among Norwegian silicon carbide smelter workers
Authors: Romundstad P , Andersen A , Haldorsen T
Published: July 2002

Objectives: To investigate associations between exposures in the silicon carbide (SiC) industry and mortality from non-malignant diseases.

Methods: Mortality among 2562 men, working in one of three silicon carbide smelters was investigated, giving 52 618 person-years of follow up from 1962 to 1996. Dose-response relations were investigated by internal comparisons using Poisson regression and by stratified standardised mortality ratio (SMR) analyses.

Results: Mortality from all causes was significantly raised compared with the Norwegian mortalities among men, SMR=1.12, (95% confidence interval (95% CI) 1.05 to1.20). An excess mortality from asthma, emphysema, and chronic bronchitis combined was found, SMR=2.21 (95% CI 1.61 to 2.95), increasing from 1.05 in the unexposed category to 2.64 (95% CI 1.44 to 4.43) in the upper category of exposure to total dust. The Poisson regression analysis confirmed the results from the stratified SMR analyses, and suggested that smoking did not act as a confounder. No association was found for circulatory mortality.

Conclusions: There was an increased mortality from asthma, emphysema, and chronic bronchitis combined among SiC workers exposed to dust .
Polychlorinated dibenzo-p-dioxin and dibenzofuran concentrations in serum samples of workers at intermittently burning municipal waste incinerators in Japan
Authors: Kumagai S , Koda S , Miyakita T , Ueno M
Published: July 2002

Objectives:To find whether or not incinerator workers employed at intermittently burning municipal incineration plants are exposed to high concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).

Methods:20 Workers employed at three municipal waste incineration plants (incinerator workers) and 20 controls were studied. The previous job, dietary, smoking, and body weight and height were obtained from a questionnaire survey. Concentrations of PCDDs and PCDFs were measured in serum samples of the workers and the deposited dust of the plants. The influence of occupational exposure on concentrations of PCDDs and PCDFs in serum samples was examined by multiple regression analysis.

Results:Dust analysis showed that dominant constituents were octachlorodibenzo-p-dioxin (OCDD) and 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin (HpCDD) among the PCDDs, and 1,2,3,4,6,7,8-heptachlorodibenzofuran (HpCDF) and octachlorodibenzofuran (OCDF) among the PCDFs. The toxicity equivalents (TEQs) of summed PCDDs and PCDFs in the deposited dust were 0.91, 33, and 11 ng TEQ/g, respectively, for plants I, II, and III. The means of TEQ in serum samples of summed PCDDs and PCDFs in the incinerator workers and controls were 22.8 and 16.4 pg TEQ/g lipid for area I, 29.4 and 19.3 pg TEQ/g lipid for area II, and 22.8 and 24.9 pg TEQ/g lipid for area III, which were almost the same as for the general population of Japan. No significant differences in the TEQ of PCDDs and TEQ of PCDDs and PCDDs were found between the incinerator workers and the controls. However, the TEQ of PCDFs was significantly higher among the incinerator workers in areas I and II, and the 1,2,3,4,6,7,8-HpCDF concentration was also significantly higher for all three areas. When the occupational exposure index for each constituent of PCDDs and PCDFs was defined as the product of the duration of employment at the incineration plant and the concentration of the constituent in the deposited dust, multiple regression analysis showed that the concentrations of HxCDF, HpCDF, and TEQ of PCDFs in serum samples increased with the occupational exposure index. The multiple regression analysis also suggested that significant factors affecting the concentrations in serum samples were area for HxCDD, age for TCDD, PeCDD, PeCDF, TEQ of PCDDs, TEQ of PCDFs, and TEQ of summed PCDDs and PCDFs, and BMI for HxCDD, HpCDD, and OCDD.

Conclusion:This study showed that incinerator workers employed at intermittently burning incineration plants were not necessarily exposed to high concentrations of PCDDs and PCDFs. However, the increases in the concentrations in serum of HxCDF, HpCDF and TEQ of PCDFs with the occupational exposure index suggest that the incinerator workers had inhaled dust containing PCDDs and PCDFs during their work.
Progressive supranuclear palsy
Authors: Rehman H U
Published: July 2002

Progressive supranuclear palsy (PSP) or Steele-Richardson-Olszewski syndrome is a neurodegenerative disease of middle and late age. It is under-diagnosed not only by general physicians but also by neurologists. The cause of PSP is not known. Exposure to toxins and viruses has been proposed in the aetiology of PSP without any concrete evidence. The features of PSP resemble those of Parkinson's disease and the two diseases are often confused. Corticobasal degeneration and multisystem atrophy are other differential diagnoses. Despite certain common features with Parkinson's disease, corticobasal degeneration, and mutisystem atrophy, there are important differences that help to differentiate it from these disorders.