Paramecium, a Model to Study Ciliary Beating and Ciliogenesis: Insights From Cutting-Edge Approaches

Cilia are ubiquitous and highly conserved extensions that endow the cell with motility and sensory functions. They were present in the first eukaryotes and conserved throughout evolution (Carvalho-Santos et al., 2011). Paramecium has around 4,000 motile cilia on its surface arranged in longitudinal rows, beating in waves to ensure movement and feeding. As with cilia in other model organisms, direction and speed of Paramecium ciliary beating is under bioelectric control of ciliary ion channels. In multiciliated cells of metazoans as well as paramecia, the cilia become physically entrained to beat in metachronal waves. This ciliated organism, Paramecium, is an attractive model for multidisciplinary approaches to dissect the location, structure and function of ciliary ion channels and other proteins involved in ciliary beating. Swimming behavior also can be a read-out of the role of cilia in sensory signal transduction. A cilium emanates from a BB, structurally equivalent to the centriole anchored at the cell surface, and elongates an axoneme composed of microtubule doublets enclosed in a ciliary membrane contiguous with the plasma membrane. The connection between the BB and the axoneme constitutes the transition zone, which serves as a diffusion barrier between the intracellular space and the cilium, defining the ciliary compartment. Human pathologies affecting cilia structure or function, are called ciliopathies, which are caused by gene mutations. For that reason, the molecular mechanisms and structural aspects of cilia assembly and function are actively studied using a variety of model systems, ranging from unicellular organisms to metazoa. In this review, we will highlight the use of Paramecium as a model to decipher ciliary beating mechanisms as well as high resolution insights into BB structure and anchoring. We will show that study of cilia in Paramecium promotes our understanding of cilia formation and function. In addition, we demonstrate that Paramecium could be a useful tool to validate candidate genes for ciliopathies.

Molecular detection of carbapenem resistance genes in rectal swabs from patients in Gulf Cooperation Council hospitals

BACKGROUND

Gram-negative organisms harbouring carbapenem resistance genes (CRGs) are spreading globally, including in Gulf Cooperation Council (GCC) countries. However, relatively few data are available about carriage of CRGs in hospitalized patients in this region.

AIM

To determine prevalence of CRG carriage and risk factors for colonization among patients in GCC hospitals.

METHODS

Rectal swabs were obtained from ∼50 intensive care unit (ICU) patients from each of 11 hospitals in five GCC countries between March and November 2019. The swabs were tested for the presence of bla_KPC, bla_NDM, bla_VIM, bla_IMP, and bla_OXA-48 CRG using a commercial polymerase chain reaction test. Data on risk factors for colonization were collected and analysed.

FINDINGS

Of 529 specimens screened, 138 (26.1%) were positive for one or more CRGs. The positivity rates among the hospitals ranged from 8.0% to 67.3%; ∼20% of the positive specimens harboured ≥2 CRGs. The most common CRG detected was bla_OXA-48, which was present in 82 specimens (15.5%). Additional CRGs included bla_NDM, bla_VIM, bla_KPC, and bla_IMP either alone or in combination. Overall, 31.1% of patients on antibiotics on admission to the ICU were positive for CRGs compared to 16.5% not on antibiotic therapy (P < 0.001). CRG detection was also more common among patients aged >65 years (P = 0.027) and increased with hospital length of stay (P = 0.025).

CONCLUSION

The rate of CRGs detected in hospitalized patients in GCC countries varied considerably. Prior antibiotic exposure, increasing age, and prolonged length of stay were associated with CRG detection.

SOME PATHOLOGIES OF THE UMBILICAL CORD AND THEIR ROLE IN PERINATAL COMPLICATIONS (CASE REPORT)

The article reports a rare case of umbilical cord twisted five times around the fetus`s neck. Our case referred to a 37 year old bedridden woman with diabetes and low amniotic fluid. As a result of performed caesarian section the newborn survived and is in a good state now. The umbilical cord wrapping around the fetus`s neck during conservative labor give rise to various complications in the fetus and is the cause of hypoxic-ischemic encephalopathy; the umbilical cord wrapping around the fetus`s neck tightly for several times causes intrauterine hypoxia; we consider ultrasonographic visualization of the umbilical cord to be included in the guidelines; cesarean intervention reduces complications during the labor and the postnatal period by 50%.

Emergence of multidrug-resistant NDM-1-producing Gram-negative bacteria in Bangladesh

The main objective of this study was to investigate the prevalence of bla (NDM-1) in Gram-negative bacteria in Bangladesh. In October 2010 at the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) laboratories, 1,816 consecutive clinical samples were tested for imipenem-resistant Gram-negative organisms. Imipenem-resistant isolates were tested for the bla (NDM-1) gene. Among 403 isolates, 14 (3.5 %) were positive for bla (NDM-1), and the predominant species were Klebsiella pneumoniae, Acinetobacter baumannii, and Escherichia coli. All bla (NDM-1)-positive isolates were resistant to multiple antibiotics. Among β-lactamase genes, bla (CTX-M-1-group) was detected in ten isolates (eight bla (CTX-M-15)), bla (OXA-1-group) in six, bla (TEM) in nine, bla (SHV) in seven, and bla (VIM) and bla (CMY) in two isolates each. The 16S rRNA methylase gene, armA, was detected in five K. pneumoniae isolates and in one E. coli isolate. rmtB and rmtC were detected in a Citrobacter freundii and two K. pneumoniae isolates, respectively. qnr genes were detected in two K. pneumoniae isolates (one qnrB and one qnrS) and in an E. coli isolate (qnrA). Transferable plasmids (60-100 MDa) carrying bla (NDM-1) were detected in 7 of the 11 plasmid-containing isolates. Pulsed-field gel electrophoresis (PFGE) analysis grouped K. pneumoniae isolates into three clusters, while E. coli isolates differed significantly from each other. This study reports that approximately 3.5 % of Gram-negative clinical isolates in Bangladesh are NDM-1-producing.

Variants of eae and stx genes of atypical enteropathogenic Escherichia coli and non-O157 Shiga toxin-producing Escherichia coli from calves

AIMS

To determine the subtypes of stx and eae genes of Shiga toxin-producing Escherichia coli (STEC) and enteropathogenic Escherichia coli (EPEC) from calves and to ascertain the typical and atypical nature of EPEC.

METHODS AND RESULTS

One hundred and eighty-seven faecal samples from 134 diarrhoeic and 53 healthy calves were investigated for the presence of stx, eae and ehxA virulence genes by polymerase chain reaction and enzyme-linked immunosorbent assay. Subtype analysis of stx(1) exhibited stx(1c) in 13 (31.70%) isolates, while that of stx(2) revealed stx(2c) in eight (24.24%) and stx(2d) in two (6.06%) isolates. Subtyping of eae gene showed the presence of eae-beta, eae-eta and eae-zeta in two, three and four isolates respectively. None of the E. coli isolates possessed stx(2e), stx(2f), eae-alpha, eae-delta, eae-epsilon and eae-xi. All EPEC isolates were atypical.

CONCLUSIONS

stx(1), stx(1c), stx(2), stx(2c), stx(2d), eae-beta, eae-eta and eae-zeta subtypes are prevalent in STEC and EPEC isolates in India.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first subtype analysis of stx(2) and eae genes of animal E. coli isolates in India and emphasizes the need to investigate their transmission to humans.

Effect of Model Ligands on Iron Redox Speciation in Natural Waters Using Flow Injection with Luminol Chemiluminescence Detection

The effects of dissolved organic compounds on the determination of nanomolar concentrations of Fe(II) have been compared using two luminol-based flow injection chemiluminescence (FI-CL) methods. One used the direct injection of sample into the luminol reagent stream, and the other incorporated on-line solid-phase extraction of the analyte on an 8-hydroxyquinoline microcolumn. The CL signals from analyses of dissolved iron species (Fe(II) and Fe(III)) with model ligands and organic compounds were examined in high-purity water and seawater. The organic compounds included natural reducing agents (e.g., ascorbic acid), nitrogen sigma-donor/pi-acceptor compounds (e.g., 1,4-dipyridine, protoporphyrin IX), aromatic compounds (e.g., 1,4-dihydroxybenzene), synthetic iron chelators (e.g., EDTA), and natural iron binding compounds (e.g., desferrioxamine B, ferrichrome A). Fe(II) determinations for both luminol FI-CL methods were affected by submicromolar concentrations of redox-active compounds, strong iron binding ligands (i.e., log K(FeL) > 6), and compounds with electron-donating functional groups in both high-purity water and seawater. This was due to reactions between organic molecules and iron species before and during analysis, rather than chemiluminescence caused by the individual organic compounds. In addition, the effects of strong ligands and size speciation on Fe(II) recoveries from seawater following acidification (pH 2) and reduction (100 microM sodium sulfite) were investigated.

Determination of sulphite using an immobilized enzyme withflow injection chemiluminescence detection

A flow injection method is reported for the determination of sulphite-based on chemiluminescent detection. Hydrogen peroxide is produced from sulphite using on-line covalently bound immobilized sulphite oxidase packed in a mini-column, which was mixed downstream and detected via cobalt(II)-catalysed chemiluminescent oxidation of luminol. The limit of detection (2 x standard deviation of the blank) was 1 x 10(-3) mmol/L with sample throughput 60 h(-1). The calibration data was linear over the range of 0.2-1.0 mmol/L with relative standard deviation (n = 4) in the range 0.9-2.0%.

Determination of iron in blood serum using ?ow injection with luminol chemiluminescence detection

A simple and rapid fl ow injection method is reported for the determination of iron in blood serum after acid digestion with HNO3 and HClO4, based on luminol CL detection in the absence of added oxidant. The detection limit (3 s) was 1.0 nmol/L with a sample throughput of 120/h. The calibration graph was linear over the range 0.001-1.0 micromol/L (r2 = 0.9974), with relative standard deviations (RSD) (n = 4) in the range 3.2-5%. The effect of interfering cations (Ca(II), Mg(II), Cu(II), Cd(II), Pb(II), Mn(II), Zn(II), Ni(II), Co(II) and Fe(III)) and anions (Cl-, SO4(2-), HCO3-, NO3-, NO2-) were studied using a luminol CL system for Fe(II) determination. The method was applied to normal blood serum and the results (1.32 +/- 0.08-1.74 +/- 0.05 mg/L) were compared with those from a spectrophotometric reference method (1.34 +/- 0.06-1.80 +/- 0.10 mg/L), which agree fairly well with the overall reference range in blood.

Flow injection chemiluminescent assays for glycerol and triglycerides using a co-immobilized enzyme reactor

A flow injection method for the determination of glycerol using a co-immobilized enzyme reactor containing glycerokinase and glycerol-3-phosphate oxidase is described. The hydrogen peroxide produced is monitored by using a luminol chemiluminescence reaction in the presence of catalyst such as Co(II). The detection limit (2.5 x blank noise) for glycerol is 7 x 10(-3) mmol/L with a sample throughput of 40/h. The calibration graph is linear over the range studied (0.2-1.0 mmol/L) with relative standard deviation 1.2-2.4%. The method is applied to the determination of glycerol in blood serum produced off-line from triglycerides using lipase isolated from bovine pancreas.

Norepinephrine concentrations in the epicardial transudate reflect early changes in adrenergic activity in the isolated perfused heart

The aim of this study was to establish whether epicardial transudates could be used to uncover small, but physiologically important changes in interstitial NE concentrations under normal and pathological conditions. Norepinephrine (NE) concentrations measured in epicardial transudate fluid were compared to NE levels in the coronary effluent in normal and pressure overload hypertrophied (POH) rat hearts. Hearts were isolated together with the stellate ganglion and perfused in the inverted position. Epicardial surface transudates, representative fluid of the interstitial myocardial compartment, and coronary effluents were collected for determination of NE levels in the presence and absence of stellate ganglion stimulation. The same protocol was repeated in the presence and absence of nisoxetine, a NE uptake blocker. NE concentrations in epicardial transudates were 16- and 19-fold higher than in the coronary effluent in both sham and POH groups, respectively. NE concentrations in the transudates but not in the coronary effluents were significantly higher (1.6-fold) in hearts with POH when compared to normal hearts. Likewise, nisoxetine (10(-5)m) increased (1.3-fold) NE concentrations in the transudates but not in the effluents of sham animals. As expected, stellate ganglion stimulation increased NE concentrations in both transudates and effluents in sham and POH hearts. In conclusion, determination of NE concentrations in epicardial transudates represents a simple, rapid and sensitive method to detect increases in adrenergic activity in normal and abnormal hearts.

Contamination of embryo transfer catheter and treatment outcome in in vitro fertilization

PURPOSE

The effect of embryo transfer (ET) catheter contamination with mucus and/or blood on treatment outcome in an in vitro fertilization (IVF) program was evaluated.

METHODS

One thousand four ET procedures in 877 patients having conventional IVF in the long (1189 cycle) and short (15 cycles) protocol were analyzed to determine the impact of catheter contamination on the incidence of retained embryos and the clinical pregnancy rate.

RESULTS

Catheter contamination with mucus and/or blood is a feature of difficult ET. Embryos were significantly more likely to be retained when the transfer catheter was contaminated with mucus (17.8 versus 3.3%) or blood (12 versus 3.3%). When the catheter was contaminated and an embryo(s) was retained and immediately retransferred, the pregnancy rate was not compromised. The pregnancy rate was significantly reduced when the ET catheter was contaminated with blood (15.5 versus 27.1%; P = 0.002), but no embryo was retained in the catheter set.

CONCLUSIONS

Catheter contamination compromises the treatment outcome in IVF only when there is no associated retained embryo(s). As increased vigilance in searching for extruded embryos may not be practical, we suggest that cervical mucus should be routinely aspirated and ET performed as atraumatically as possible.

In vitro fertilization with low-dose clomiphene citrate stimulation in women who respond poorly to superovulation

PURPOSE

Our experience with IVF using low-dose clomiphene citrate for stimulation in "non-" and "poor" responders was reviewed and the treatment outcomes with the previous controlled ovarian stimulation cycles in which hMG and GnRH agonist were used were compared.

METHODS

The treatment outcome in 11 non- and 20 poor responders having 30 and 53 clomiphene citrate IVF treatment cycles, respectively, were compared with the treatment outcome in the previous long-protocol buserelin/hMG cycles.

RESULTS

The clinical pregnancy rates per oocyte collection achieved in the first clomiphene citrate cycle in non (9.1%)- and poor (10%) responders were comparable to those achieved by poor responders (11.9%) who had buserelin/hMG using the long protocol. Although the numbers were small, a similar pregnancy rate could still be achieved in poor responders up to the third attempt using clomiphene citrate.

CONCLUSIONS

IVF using long-protocol buserelin/hMG is more successful than using clomiphene citrate stimulation. However, this advantage may not be significant in those women with a previous poor response to buserelin/hMG. It is suggested that for such poor responders, three attempts of IVF in a clomiphene citrate cycle may offer a viable therapeutic alternative before reverting to more stressful, expensive, and time-consuming treatment.

Multiple attempts at embryo transfer: does this affect in-vitro fertilization treatment outcome?

In this study, we retrospectively analysed data from 877 patients who had 1204 embryo transfer procedures following in-vitro fertilization (IVF) at Midland Fertility Services, UK, between January 1991 and December 1995 to investigate the factors contributing to failure of embryo transfer at first attempt and the impact of immediate retransfer of retained embryos on the treatment outcome. Embryos were significantly more likely to be retained when the embryo transfer catheter was contaminated with mucus (3.3 versus 17.8%, P = 0.000001) or blood (3.3 versus 12%, P = 0.00001) and when the transfer procedure was difficult compared with when it was easy (20.3 versus 0.8%, P = 0.00001). There was no significant difference in the clinical pregnancy rate between those who had all their embryos transferred at the first attempt (24.7%) and those who required more than one attempt (23.2%). The types of embryo transfer catheter used in the unit did not show any difference in terms of embryo retention. Although we recommend aspiration of cervical mucus in order to reduce the rate of retained embryos, there is no evidence from our study to suggest that pregnancy rate is compromised when embryos are retained, provided they are discovered and immediately retransferred into the uterine cavity. Immediate retransfer is more convenient to the patients and reduces the laboratory workload without compromising the treatment outcome.

Chemiluminescent assays for choline and phospholipase-D using a flow injection system

A flow injection chemiluminescent method is described for the determination of choline. The method is based on the production of hydrogen peroxide from choline using on-line covalently bound immobilized choline oxidase column. The product is mixed downstream and detected via the cobalt catalyzed chemiluminescent oxidation of luminol. The detection limit is 1 x 10(-7) mol/L, with rsd 1.8 to 2.8% in the range 2-10 x 10(-5) mol/L. The sample throughput is 30 per hour. The method was applied to the determination of choline produced off-line from phosphatidylcholine using phospholipase-D isolated from cabbage.

Flow-injection chemiluminescent determination of glycerol-3-phosphate and glycerophosphorylcholine using immobilized enzymes

Flow injection procedures with immobilized enzyme mini-columns are described for the determination of glycerol-3-phosphate, and glycerophosphorylcholine with chemiluminescent detection. The hydrogen peroxide produced on-line is coupled with a luminol (5-amino-2,3,-dihydro-1,4-phthalazinedione) peroxidation chemiluminescent system. The detection limits for glycerol-3-phosphate and glycerophosphorylcholine are 5 x 10(-7) M and 1 x 10(-6) M respectively with r.s.d. < 2%. The sample throughput is 40/h. The immobilized enzyme columns did not show any deterioration in activity after usage for 3 months.

[HELLP syndrome. Apropos of a series of 9 cases without disseminated intravascular coagulation]

The Hellp syndrome defined as the association of micro-angiopathic haemolytic anemia, hepatic cytolysis and thrombocytopenia, correspond to a severe form of gravidic toxemia, combined to manifestations of classic-pre-eclampsia. This retrospective study, conducted over 6 years, concerns 9 cases of Hellp syndrome, including 2 occurring during the immediate post-partum. Only cases where this biological triad was obvious and not associated with manifestations of disseminated intravascular coagulation, were considered in this study. In addition to the usual criteria of gravidic toxemia, the early clinical manifestation occur, in this study, between 28 and 38 weeks of amenorrhea and gastrointestinal manifestations are predominant. The physiopathogenic hypotheses of this syndrome remain variable and management varies depending on the authors. Treatment is that of pre-eclampsia. Medical treatments (steroids, heparin, immunosuppressants,...) are discussed, but severe feto-maternal complications require, most of the time, a surgical approach, depending on the number of pregnancies, the obstetrical conditions, the stage of the pregnancy and the severity of the syndrome.