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Biomedical subjects

M Bahar

Publications and source records attributed to M Bahar.

At least 19 recordsLinked to original sources
PubMed2006

Application of the use of high-throughput technologies to the determination of protein structures of bacterial and viral pathogens.

The Structural Proteomics In Europe (SPINE) programme is aimed at the development and implementation of high-throughput technologies for the efficient structure determination of proteins of biomedical importance, such as those of bacterial and viral pathogens linked to human health. Despite the challenging nature of some of these targets, 175 novel pathogen protein structures (approximately 220 including complexes) have been determined to date. Here the impact of several technologies on the structural determination of proteins from human pathogens is illustrated with selected examples, including the parallel expression of multiple constructs, the use of standardized refolding protocols and optimized crystallization screens.

Animals↗
PubMed2006

SPINE workshop on automated X-ray analysis: a progress report.

The Structural Proteomics In Europe (SPINE) consortium contained a workpackage to address the automated X-ray analysis of macromolecules. The aim of this workpackage was to increase the throughput of three-dimensional structures while maintaining the high quality of conventional analyses. SPINE was able to bring together developers of software with users from the partner laboratories. Here, the results of a workshop organized by the consortium to evaluate software developed in the member laboratories against a set of bacterial targets are described. The major emphasis was on molecular-replacement suites, where automation was most advanced. Data processing and analysis, use of experimental phases and model construction were also addressed, albeit at a lower level.

Algorithms↗
PubMed2006

Dextran 40 (Rheomacrodex) or Polygeline (Haemaccel) as an epidural patch for post dural puncture headache: a neurotoxicity study in a rat model of Dextran 40 and Polygeline injected intrathecally.

BACKGROUND AND OBJECTIVE: Although an epidural autologous blood patch is considered the most effective treatment for post dural puncture headache, which sometimes occurs following spinal or inadvertent spinal anaesthesia, there remains a need for alternative materials for epidural patches. We investigated the potential neurotoxicity of Dextran 40 (Rheomacrodex) and Polygeline (Haemaccel) used for this purpose in a rat model. METHODS: Repeated boluses of 10% Dextran 40, 3.5% Polygeline or 0.9% saline were injected intrathecally over a period of 1 month in three groups of rats. RESULTS: No behavioural or clinical derangements were observed in any of the three groups during this period. After sacrifice of the animals at the end of the experiment, no significant differences in the histopathological appearances of the spinal cords in the three groups were observed. No toxic effects diminishing viability of spinal cord cells were evident. Similarly, viability of renal, hepatic and peripheral blood mononuclear cells remained unaffected (98% +/- 2%). CONCLUSIONS: No deleterious effects, clinical or cellular, were evident in this rat model when Dextran 40 or Polygeline were injected intrathecally. Thus, both substances can be considered as possible alternative materials for epidural patches.

Animals↗
PubMed2006

Fluid preload before spinal anaesthesia in Caesarean section: the effect on neonatal acid-base status.

BACKGROUND AND OBJECTIVE: We evaluated the effect of two different preload solutions: (i) Ringer's lactate (compound sodium lactate intravenous infusion BP) and (ii) 0.9% sodium chloride solution on the neonatal acid-base status of the newborn infants. The two standard regimens were compared to detect a possible difference. METHODS: A 2 L crystalloid fluid bolus was administered immediately before spinal anaesthesia for elective Caesarean section in two groups of 20 healthy parturients, while rigorously maintaining maternal normotension. RESULTS: No significant differences in the Apgar scores at 1 and 5 min, or infant well-being were demonstrated in either of the two groups. The data show that umbilical artery PCO2 is lower in the Ringer's lactate group and that pH is insignificantly higher by 0.03. CONCLUSIONS: The choice of Ringer's lactate or saline for fluid preload does not have any effect on neonatal well-being.

Acid-Base Equilibrium↗
PubMed2005

Enumeration of bacteriophages in water by different laboratories of the European Union in two interlaboratory comparison studies.

As part of a European project on bacteriophages in bathing waters two interlaboratory comparison studies were carried out (May 1997 and March 1998). During these studies phage reference materials as well as naturally polluted standard samples were analysed in 16 European laboratories. Three groups of bacteriophages were tested using standardised methods: somatic coliphages, F-specific RNA-phages and phages of Bacteroides fragilis. Many of the participating laboratories applied one or more of the phage methods for the first time, after a one-week training session in a central laboratory. Nevertheless, the values of repeatability (r=1.35-1.38 calculated on log(10)-scale) and reproducibility (R=1.52-2.04 calculated on log(10)-scale) when analysing phage reference materials were close to the theoretical optimum for a Poisson distribution. When analysing the naturally polluted samples more variation in results within and between laboratories was found (r=1.63-2.34; R=3.10-5.72), in comparison with the results obtained with the pure phage reference materials.

Bacteriophages↗
PubMed2004

The role of meatal disinfection in preventing catheter-related bacteriuria in an intensive care unit: a pilot study in Turkey.

The purpose of this study was to investigate the efficacy of antiseptics meatal care in preventing catheter-related urinary tract infections (UTIs) in patients with an indwelling urinary catheter in the intensive care unit of Osmangazi University Medical School. One hundred patients were divided into four groups (25 per group) and treated with once or twice daily application of chlorhexidine gluconate or povidone-iodine. A control group was also studied (N=30). Urine samples were taken weekly and cultures were evaluated quantitatively. Meatal swabs were obtained on the first, fifth, and 10th day and determinated semiquantitatively. UTI was defined as bacteriuria with 10(5)cfu/L. Cultures showing no growth or mixed growths were stated as negative for UTI. UTI developed in 16 patients on days two, three, four, five and seven (including control group). Dominant micro-organisms in the meatal area were found to be Candida species. In nine cases the causative agents of UTI were Candida species. It was therefore decided that the use of antiseptics to clean the periurethral area provides no benefit in decreasing the rate of bacteriuria.

Administration, Topical↗
PubMed2002

Intracellular Ca++/Mg++ homeostasis during postnatal growth of experimental rats. Multiple time-point study.

In most tissues, various cell membrane ion transporting systems are not fully developed and/or maximally active at the prenatal and early postnatal stage. Their progressive development and expression are a function of growth and maturity. We performed a multiple time-point study, in order to investigate the ability of a variety of tissues to maintain appropriate Ca++ and Mg++ homeostasis at different stages of postnatal development. Total intracellular Ca++ in one-week-old rat liver, brain and spinal cord tissues was significantly elevated, compared to mature animals. It increased further through the first three weeks of gestation. Intracellular Ca++ gradually and significantly declined in adult and mature animal groups. Alterations in total intracellular Mg++ of the same tissue samples, although not so profound, paralleled changes in total intracellular Ca++. We conclude that a developmental switch in intracellular Ca++ and Mg++ homeostasis occurs one to three weeks following birth. It might be related to the incomplete development of Ca++ and Mg++ transmembrane transporting systems, previously reported as being only partially expressed at the early postnatal stage. These developmental alterations in total intracellular Ca++ and Mg++ content might serve as a regulatory mechanism, adjusting cell activities to the physiological requirements of the growing and maturing animal.

Animals↗
PubMed2002

Willipelletierine, a new diterpenoid alkaloid from Consolida scleroclada (Boiss.) Schrod.

From the aerial parts of Consolida scleroclada (Boiss.) Schrod. collected in Turkey, a new diterpenoid alkaloid named willipelletierine has been isolated along with the known diterpenoid alkaloids aconitine, lapaconidine, and delcosine. The structure for willipelletierine was established on the basis 1H, 13C, DEPT, homonuclear 1H COSY, HETCOR and NOESY NMR studies.

Alkaloids↗
PubMed2001

Lateral recumbent head-down posture for epidural catheter insertion reduces intravascular injection.

PURPOSE: The unintentional and unrecognized cannulation of an extradural vein is a potentially serious complication of an epidural anesthetic. The present study was undertaken to assess the incidence of blood vessel puncture related to epidural catheterization performed in three different body positions. METHODS: The study was conducted in 900 (three groups of 300) obstetric patients undergoing continuous epidural analgesia during their labour and who were randomly allocated to three groups. Epidural catheterization was performed with patients in the sitting, lateral recumbent horizontal, or lateral recumbent head-down position. RESULTS: There was a lower incidence of vessel cannulation when this procedure was performed in the lateral recumbent head-down position (2%) than in the lateral recumbent horizontal (6%) and in the sitting position (10.7%). CONCLUSION: Adoption of the lateral recumbent head-down position for the performance of lumbar epidural blockade, in labour at term, reduces the incidence of lumbar epidural venous puncture.

Adolescent↗
PubMed2001

Intrathecal anaesthesia alters intracellular Ca2+/Mg2+ homeostasis in the spinal cord neurones of experimental rats.

BACKGROUND AND OBJECTIVE: The effect of anaesthesia induced by intrathecal injection of 6.3% MgSO4 or 4% lidocaine on intracellular electrolyte homeostasis in spinal cord neurones of a rat model was investigated. METHODS: Intracellular Ca2+, Mg2+, Na+ and K+ concentrations were determined at different times after intrathecal administration of NaCl (saline, a control group), MgSO4 or lidocaine. RESULTS: In both thoracic and lumbar spinal cord segments, Ca2+ concentrations rose significantly 30 min and 2 h after 6.3% MgSO4 injection, and after 24 h were still significantly increased compared with the values obtained from the control group which were subjected to sham 'anaesthesia' by saline injection (172, 121 and 108 ng mg-1 protein vs. control 23 ng mg-1 protein, respectively, in the thoracic segment and 222, 229 and 176 ng mg-1 protein vs. control 43 ng mg-1 protein, respectively, in the lumbar segment). Lidocaine injection also produced a significant increase in intracellular Ca2+ in the thoracic and lumbar spinal cord segments (69, 64 and 53 ng mg-1 protein vs. control 33.4 ng mg-1 protein and 26, 94 and 46 ng mg-1 protein vs. 23 ng mg-1 protein respectively). Only a modest rise in intracellular Mg2+ was observed after intrathecal MgSO4 or lidocaine injection (27 ng mg-1 protein vs. 23 ng mg-1 protein). Na+ and K+ concentrations decreased 24 h after MgSO4 and 1 h after lidocaine injection. CONCLUSION: Intrathecal anaesthesia by MgSO4 or lidocaine alters intracellular electrolyte homeostasis in spinal cord neurones of experimental rats. A possible common mechanism of action via Ca2+ ion channels is discussed.

Anesthesia, Spinal↗
PubMed2001

Optimisation of the ISO-method on enumeration of somatic coliphages (draft ISO 10705-2).

As part of the EU project "Bacteriophages in Bathing Waters" (January 1996-June 1999) research was carried out to optimise the method for detection and enumeration of somatic coliphages in water as described in ISO/CD 10705-2 of August 1995. It was concluded that this draft ISO standard needed to be amended in certain aspects. For determining the viable count of the host culture WG5 Escherichia coli, a membrane filtration technique should be used instead of spread plate technique as the latter gives lower and less reproducible results. A freshly prepared inoculum culture of host strain WG5 should be used instead of a frozen inoculum culture as freezing of the inoculum culture is found to negatively influence the phage counts. The double agar layer method (DAL) is preferred to the single agar layer method (SAL) for performing the phage analysis as the DAL method gives higher phage counts than the SAL method.

Agar↗
PubMed2000

Substances used for local and general anaesthesia in major surgery suppress proliferative responsiveness of normal rat peripheral blood mononuclear cells in culture.

We studied the direct effect of intravenous anaesthetics, local anaesthetics and premedication drugs in common use for major surgery, on the spontaneous versus lectin induced proliferation of cultured normal rat peripheral blood mononuclear cells, not exposed to surgical or any other trauma prior to culture. Peripheral blood mononuclear cells were incubated in cell-culture medium in the presence or in the absence of propofol, ketamine, fentanyl, midazolam, thiopental sodium, lidocaine or etomidate. The cells proliferated either spontaneously or under stimulation with a lectin phytohaemagglutinine P for 72 h. The proliferation rate was evaluated by 2H-Thymidine incorporation. Fentanyl, thiopental sodium, lidocaine and etomidate significantly inhibited phytohaemagglutinine P induced 3H-Thymidine incorporation in cultured rat peripheral blood mononuclear cells. Counts per minute of the cultures treated with these drugs were 1667.80 +/- 745.72, 1614.1 +/- 615.00, 1688.0 +/- 615.0 and 1549 +/- 560.41, respectively, compared with the phytohaemagglutinine P stimulated positive control counts per minute, 13488 +/- 4305.6 (P < 0.001 in each comparison). Propofol, ketamine and midazolam inhibited the lectin-induced cell proliferation to levels not statistically different from the baseline. Counts per minute of these cultures were 1361.90 +/- 745.73; 1108.90 +/- 751.33 and 1518.10 +/- 848.88, respectively. Compared either with the baseline 972.57 +/- 356.73 counts per minute or to the positive control culture counts per minute, 13488 +/- 4305.6 the difference was statistically significant (P < 0.001) in each comparison. All the substances tested in this study proved capable of exerting direct inhibitory effect on circulating immunocompetent cells, because the latter were not subjected to any other immunosuppressive factor, be it operative trauma, blood transfusion, malnutrition, drug abuse, prior to culture. The possible theoretical and practical implications are discussed in this study.

Anesthetics, General↗
PubMed2000

Conservation of a pseudomonad-like hydrocarbon degradative ferredoxin oxygenase complex involved in rhizopine catabolism in Sinorhizobium meliloti and Rhizobium leguminosarum bv. viciae.

In Sinorhizobium meliloti the mocCABR genes have previously been shown to be required for rhizopine (3-O-methyl-scyllo-inosamine, 3-O-MSI) catabolism. We show that the mocDE(F) gene cluster is also needed. MocDE(F), which is involved in the catabolism of 3-O-MSI to its demethylated form scyllo-inosamine (SI) has homology to components that would comprise a ferredoxin-oxygenase system. The mocCABRDE(F) suite of genes is required for 3-O-MSI catabolism in both S. meliloti and R. leguminosarum bv. viciae. However, SI catabolism in S. meliloti requires mocCABR, whereas only mocCA are required for its catabolism in R. leguminosarum suggesting the two species require different chromosomal genes which act in concert with moc genes for the catabolism of rhizopine.

Amino Acid Motifs↗
PubMed2000

Diterpenoid alkaloids from the aerial parts of Aconitum anthora L.

Isolation and identification of six diterpenoid alkaloids, from Aconitum anthora L. are described. All proton detected 2D NMR techniques have been used for unambiguous 1H and 13C chemical shift assignments of guan-fu-base-Y (6). This is the first investigation of the diterpenoid alkaloids of this plant species.

Alkaloids↗
PubMed1999

Spinal anaesthesia with gamma hydroxybutyrate. A study in a rat model.

Gamma hydroxybutyric acid, a central inhibitory neurotransmitter and a cerebral metabolite of gamma-aminobutyric acid, is present in high concentrations in the mammalian hypothalamus and basal ganglia. Its sodium salt gamma hydroxybutyrate has been effectively used as an intravenous anaesthetic agent, and as an oral sedative, and in the management of the alcohol withdrawal syndrome. In an animal model, using 72 Wistar strain rats allocated to one of six groups of 12 animals each, with implanted lumbar intrathecal catheters, we examined whether gamma hydroxybutyrate, 20% 40 microL (32 mg kg-1) administered alone or combined with fentanyl, gamma hydroxybutyrate 20% 20 microL (16 mg kg-1), fentanyl 0.005% 20 microL (4 mg kg-1) as an intrathecal bolus, provides intraoperative anaesthesia, comparable with that produced by intrathecal lignocaine. We demonstrated that gamma hydroxybutyrate, given by an intrathecal bolus in the rat model, produced reversible segmental antinociception, together with muscular relaxation of the abdominal wall and rear limbs. This is accompanied by moderate sedation without haemodynamic or respiratory depression. This agent may thus be promising for use as a spinal anaesthetic drug.

Anesthesia, Spinal↗
PubMed1998

A model for the catabolism of rhizopine in Rhizobium leguminosarum involves a ferredoxin oxygenase complex and the inositol degradative pathway.

Rhizopines are nodule-specific compounds that confer an intraspecies competitive nodulation advantage to strains that can catabolize them. The rhizopine (3-O-methyl-scyllo-inosamine, 3-O-MSI) catabolic moc gene cluster mocCABRDE(F) in Rhizobium leguminosarum bv. viciae strain 1a is located on the Sym plasmid. MocCABR are homologous to the mocCABR gene products from Sinorhizobium meliloti. MocD and MocE contain motifs corresponding to a TOL-like oxygenase and a [2Fe-2S] Rieske-like ferredoxin, respectively. The mocF gene encodes a ferredoxin reductase that would complete the oxygenase system, but is not essential for rhizopine catabolism. We propose a rhizopine catabolic model whereby MocB transports rhizopine into the cell and MocDE and MocF (or a similar protein elsewhere in the genome), under the regulation of MocR, act in concert to form a ferredoxin oxygenase system that demethylates 3-O-MSI to form scyllo-inosamine (SI). MocA, an NAD(H)-dependent dehydrogenase, and MocC continue the catabolic process. Compounds formed then enter the inositol catabolic pathway.

Amino Acid Sequence↗