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S Nikolaou

Publications and source records attributed to S Nikolaou.

9 recordsLinked to original sources
PubMed2006

Extending from PARs in Caenorhabditis elegans to homologues in Haemonchus contortus and other parasitic nematodes.

Signal transduction molecules play key roles in the regulation of developmental processes, such as morphogenesis, organogenesis and cell differentiation in all organisms. They are organized into 'pathways' that represent a coordinated network of cell-surface receptors and intracellular molecules, being involved in sensing environmental stimuli and transducing signals to regulate or modulate cellular processes, such as gene expression and cytoskeletal dynamics. A particularly important group of molecules implicated in the regulation of the cytoskeleton for the establishment and maintenance of cell polarity is the PAR proteins (derived from partition defective in asymmetric cell division). The present article reviews salient aspects of PAR proteins involved in the early embryonic development and morphogenesis of the free-living nematode Caenorhabditis elegans and some other organisms, with an emphasis on the molecule PAR-1. Recent advances in the knowledge and understanding of PAR-1 homologues from the economically important parasitic nematode, Haemonchus contortus, of small ruminants is summarized and discussed in the context of exploring avenues for future research in this area for parasitic nematodes.

Animals↗
PubMed2006

Prospects for exploring molecular developmental processes in Haemonchus contortus.

Haemonchus contortus of small ruminants is a parasitic nematode of major socio-economic importance world-wide. While there is considerable knowledge of the morphological changes which take place during the life cycle of H. contortus, very little is understood about the molecular and biochemical processes which govern developmental changes in the parasite. Recent technological advances and the imminent genomic sequence for H. contortus provide unique opportunities to investigate the molecular basis of such processes in parasitic nematodes. This article reviews molecular and biochemical aspects of development in H. contortus, reports on some recent progress on signal transduction molecules in this parasite and emphasises the opportunities that new technologies and the free-living nematode, Caenorhabditis elegans, offer for investigating developmental aspects in H. contortus and related strongylid nematodes, also in relation to developing novel approaches for control.

Animals↗
PubMed2006

Isolation and characterization of class II myosin genes from Haemonchus contortus.

In this study, cDNAs encoding myosin from the parasitic nematode Haemonchus contortus were isolated and characterized. Several exhibited a considerable degree of sequence variation at the nucleotide and limited divergence at the amino acid levels within the various functional domains. The results suggest that the cDNAs isolated represented a single myosin heavy chain, which, by comparison with a number of other myosins, is inferred to represent a homologue of a muscle myosin (CeMHCA) of the free-living nematode Caenorhabditis elegans. The findings could have implications for investigating cytoskeletal dynamics and/or signalling pathways.

Amino Acid Sequence↗
PubMed2006

Class II myosins in nematodes-- genetic relationships, fundamental and applied implications.

Myosins are represented by a wide range of different classes of molecule, of which the most extensively studied are the class II myosins which drive muscle contraction and cell organization; the functional unit of class II myosins comprises two myosin heavy chains (MHCs). This minireview gives an update on class II MHCs of nematodes and describes a comparative analysis of MHC genes from nematodes and other organismal groups. Genetic analyses of sequence data for the four functional domains of MHCs (i.e., the SH3-like N-terminal, head, neck and tail domains) reveal a delineation between both the nematode and non-nematode myosins and between muscle and non-muscle myosins. The distinctiveness of the MHCs of nematodes suggests functional and tissue specialization. The elucidation of the functional roles of myosins and other molecules in specific signaling pathways in nematodes has the potential to lead to new intervention strategies for parasites via the specific disruption or interruption of key developmental processes, having biotechnological implications in the longer term.

Amino Acid Sequence↗
PubMed2006

Resistance of Mycobacterium tuberculosis isolates in different populations in Greece during 1993-2002.

OBJECTIVE: To document the prevalence of resistance of Mycobacterium tuberculosis to isoniazid (INH), rifampicin (RMP) and both combined (multidrug resistance [MDR]) in Greece from 1993 to 2002. DESIGN: We studied a single sputum sample per patient from 4108 patients referred to the Greek National Referral Centre for Mycobacteria. Patients were divided into native Greeks, immigrants and repatriated Greeks originating from the former Soviet Union. Prior treatment status was not recorded. RESULTS: A statistically significant increase in resistance to INH and RMP and MDR was noted comparing the years 1993-1997 to 1998-2002 (P < 0.0001). Resistance to INH and RMP and MDR rose from 5.6% to 7.71%, from 1.57% to 4.49% and from 1.23% to 3.98%, respectively, among native Greeks and from 23.63% to 32.91%, from 6.36% to 15.19% and from 6.36% to 13.92% among repatriated Greeks. Smaller changes were seen among immigrants (from 15.43% to 9.57% for INH, from 5.51% to 6.12% for RMP and from 5.71% to 5.32% for MDR). CONCLUSION: We documented an increase in M. tuberculosis resistance to INH and RMP, and MDR. This was mainly limited to native and repatriated Greeks. Although this is likely the result of immigration and of mismanagement of index cases in Greece, molecular methods are needed to better describe the situation.

Antitubercular Agents↗
PubMed2001

Analysis of developmentally regulated genes of the parasite Haemonchus contortus.

Differential regulation of gene expression in the development of Haemonchus contortus was analysed using RNA arbitrarily-primed PCR. A study of third-stage larval and adult H. contortus revealed large differences between the two stages; 32 and 30% unique third-stage larval and adult RNA arbitrarily-primed PCR products, respectively. This finding is consistent with a high degree of differential gene expression between these developmental stages. A number of adult products were sequenced, revealing 11 molecules to be similar to deposits within sequence databases. Four other molecules that did not have significant similarity to sequences in the databases may represent developmentally regulated genes specific to H. contortus. Northern analysis of the putative adult-expressed molecules with homologues in the databases confirmed that four were expressed only in adults, while four were expressed in both stages, but had different sized transcripts. This may reflect differential splicing, or expression of closely related but different molecules at different life cycle stages. Two molecules were present in mRNA populations from both stages, suggesting these were false stage-associated molecules. No transcript was detected for one molecule by Northern analysis, probably due to low level of expression. In situ hybridisation analysis was used to localise expression of transcripts in the adult parasite, in particular, to gain some insight into the nature of those molecules with no known predicted function.

Amino Acid Sequence↗
PubMedDate not supplied

[Transanal endorectal pull-through with or without laparoscopic assistance? Development of an experimental model].

The transanal approach is a relatively new technique for surgery of Hirschsprung's disease. The purpose of this experimental study was to evaluate and compare the transanal endorectal pull-through when it takes place with laparoscopic assistance, according to Soave-Georgeson procedure and without laparoscopic assistance. We used two separated groups of animals. In the 1st group the transanal endorectal pull-through was performed by retrograde transanal mucosectomy with laparoscopic devascularization of the colon and in the 2nd group the transanal endorectal pull-through was performed without laparoscopic assistance. In the 1st group the transitional zone of the colon was determined laparoscopically while in the 2nd group during the perineal devascularization of the bowel. In both groups end to end coloanal anastomosis was performed in the same way. The postoperative course was uneventful, no severe long-term problems were observed. Four months after operation the experimental subjects of the 1st group had 3-4 discharges in 24 hours. While the experimental subjects of the 2nd group had 5-7 discharges in 24 hours. Manometric resting anal sphincters pressure in the 1st group averaged 77 +/- 16 mmHg compared with 74 +/- 15 mmHg in the 2nd group. The transanal colectomy technically can be performed with or without laparoscopic assistance. However the advantages of laparoscopic assistance are the following: 1) more exact determination of transitional zone; 2) easier separation of peritoneal reflection, 3) better control of final position of the colon; 4) minor retraction on the perineal muscles.

Anal Canal↗