Impact of stereoacuity on simulated cataract surgery ability

BACKGROUND AND OBJECTIVES

There exists a long-standing perception that diminished stereoacuity has a detrimental effect on microsurgical ability and skills acquisition. This has potential implications on the enrolment of surgical trainees into ophthalmology and other microsurgery specialities. However, strong evidence in this area is lacking. This case-control study aims to establish the exact level of stereopsis impairment at which a statistical drop in surgical performance occurs.

METHODS

Fifty participants were enrolled from the University of Dundee Medical School and the NHS Tayside Foundation Doctor programme. Participants were assessed for their stereopsis level before completing an orientation module on an ophthalmic surgical simulator. They were then required to repeat a task four times. Automated and objective performance levels were recorded and analysed.

RESULTS

Nineteen (38%) had stereopsis lower than the defined normal of 60 seconds of arc (arcsec). Statistical analysis found no correlation between visual acuity and surgical performance. No statistical difference was found between performance scores and stereoacuities of 30, 60 and 120 arcsec. A statistically significant difference was discovered in the surgical performance of participants with a stereoacuity worse than 120 arcsec (total score = -69.85) as compared to the ones with a stereoacuity of 120 arcsec or better (total score = -42.23) with p = 0.010.

CONCLUSIONS

This study provides evidence of a specific level of stereopsis where statistical degradation of surgical performance occurs. The findings of this work may help formulate policy on stereoacuity standards required to commence microsurgical training.

Meropenem potentiation of aminoglycoside activity against Pseudomonas aeruginosa: involvement of the MexXY-OprM multidrug efflux system

Objectives

To assess the ability of meropenem to potentiate aminoglycoside (AG) activity against laboratory and AG-resistant cystic fibrosis (CF) isolates of Pseudomonas aeruginosa and to elucidate its mechanism of action.

Methods

AG resistance gene deletions were engineered into P. aeruginosa laboratory and CF isolates using standard gene replacement technology. Susceptibility to AGs ± meropenem (at ½ MIC) was assessed using a serial 2-fold dilution assay. mexXY expression and MexXY-OprM efflux activity were quantified using quantitative PCR and an ethidium bromide accumulation assay, respectively.

Results

A screen for agents that rendered WT P. aeruginosa susceptible to a sub-MIC concentration of the AG paromomycin identified the carbapenem meropenem, which potentiated several additional AGs. Meropenem potentiation of AG activity was largely lost in a mutant lacking the MexXY-OprM multidrug efflux system, an indication that it was targeting this efflux system in enhancing P. aeruginosa susceptibility to AGs. Meropenem failed to block AG induction of mexXY expression or MexXY-OprM efflux activity, suggesting that it may be interfering with some MexXY-dependent process linked to AG susceptibility. Meropenem potentiated AG activity versus AG-resistant CF isolates, enhancing susceptibility to at least one AG in all isolates and susceptibility to all tested AGs in 50% of the isolates. Notably, meropenem potentiation of AG activity was linked to MexXY in some but not all CF isolates in which this was examined.

Conclusions

Meropenem potentiates AG activity against laboratory and CF strains of P. aeruginosa, both dependent on and independent of MexXY, highlighting the complexity of AG resistance in this organism.

The aminoglycoside resistance-promoting AmgRS envelope stress-responsive two-component system in Pseudomonas aeruginosa is zinc-activated and protects cells from zinc-promoted membrane damage

Exposure of wild-type (WT) Pseudomonas aeruginosa PAO1 to ZnCl2 (Zn) yielded a concentration-dependent increase in depolarization of the cytoplasmic membrane (CM), an indication that this metal is membrane-damaging. Consistent with this, Zn activated the AmgRS envelope stress-responsive two-component system (TCS) that was previously shown to be activated by and to protect P. aeruginosa from the membrane-damaging effects of aminoglycoside (AG) antibiotics. A mutant lacking amgR showed enhanced Zn-promoted CM perturbation and was Zn-sensitive, an indication that the TCS protected cells from the CM-damaging effects of this metal. In agreement with this, a mutant carrying an AmgRS-activating amgS mutation was less susceptible to Zn-promoted CM perturbation and more tolerant of elevated levels of Zn than WT. AG activation of AmgRS is known to drive expression of the AG resistance-promoting mexXY multidrug efflux operon, and while Zn similarly induced mexXY expression this was independent of AmgRS and reliant on a second TCS implicated in mexXY regulation, ParRS. MexXY did not, however, contribute to Zn resistance or protection from Zn-promoted CM damage. Despite its activation of AmgRS and induction of mexXY, Zn had a minimal impact on the AG resistance of WT P. aeruginosa although, given that Zn-tolerant AmgRS-activated amgS mutant strains are AG resistant, there is still the prospect of this metal promoting AG resistance development in this organism.

Microscopy and culture for Trichomonas vaginalis: are both required?

Many genitourinary medicine clinics have stopped routinely performing both wet preparation microscopy and cultures to diagnose Trichomonas vaginalis (TV). Our directorate stopped microscopy when screening asymptomatic women. This audit considers whether both tests continue to be warranted for symptomatic female patients. The discrepancy between microscopy and culture results leads us to recommend that both remain necessary. Sampling standardization and improved documentation are discussed.

Vision screening in children: a retrospective study of social and demographic factors with regards to visual outcomes

Background

Amblyopia and its risk factors have been demonstrated to be more common among children from low socioeconomic backgrounds. We sought to investigate this association in a region with orthoptic-delivered screening and whole population coverage, and to also examine the association of the Health Plan Indicator (HPI) with screening outcome.

Methods

Screening examination outcomes, postcodes and HPIs were extracted from the community child health database for every child who underwent preschool vision screening between March 2010 and February 2011 Tayside. We obtained the Scottish Index of Multiple Deprivation score for every child as a measure of area-based deprivation. We assessed the vulnerability/needs of the individual family through the HPI—‘Core’ (children and families receiving universal health visiting service), ‘Additional’ (receiving additional health/social support) and ‘Intensive’ (receiving high levels of support). The outcomes from follow-up examinations for those who failed screening were extracted from the orthoptic department database.

Results

4365 children were screened during the year 2010–2011 of whom 523 (11.9%) failed. The odds of children from the least deprived socioeconomic group passing the visual screening test was 1.4 times higher than those from the most deprived socioeconomic group (OR 1.4, 95% CI 1.07 to 1.89, p=0.01). The odds of a child from a family assigned as ‘Intensive’ failing the preschool visual screening test was three times greater than the odds of a child from a family assigned as ‘Core’ (OR 3.59, 95% CI 1.6 to 7.8, p=0.001).

Conclusions

We found that children from the most deprived backgrounds and those from unstable homes were more likely to fail preschool vision screening.

AmgRS-mediated envelope stress-inducible expression of the mexXY multidrug efflux operon of Pseudomonas aeruginosa

AmgRS is an envelope stress-responsive two-component system and aminoglycoside resistance determinant in Pseudomonas aeruginosa that is proposed to protect cells from membrane damage caused by aminoglycoside-generated mistranslated polypeptides. Consistent with this, a ΔamgR strain showed increased aminoglycoside-promoted membrane damage, damage that was largely absent in AmgRS-activated amgS-mutant strains. Intriguingly, one such mutation, V121G, while providing for enhanced resistance to aminoglycosides, rendered P. aeruginosa susceptible to several ribosome-targeting nonaminoglycoside antimicrobials that are inducers and presumed substrates of the MexXY-OprM multidrug efflux system. Surprisingly, the amgSV 121G mutation increased mexXY expression threefold, suggesting that export of these nonaminoglycosides was compromised in the amgSV 121G mutant. Nonetheless, a link was established between AmgRS activation and mexXY expression and this was confirmed in studies showing that aminoglycoside-promoted mexXY expression is dependent on AmgRS. While nonaminoglycosides also induced mexXY expression, this was not AmgRS-dependent, consistent with these agents not generating mistranslated polypeptides and not activating AmgRS. The aminoglycoside inducibility of mexXY was abrogated in a mutant lacking the AmgRS target genes htpX and PA5528, encoding a presumed cytoplasmic membrane-associated protease and a membrane protein of unknown function, respectively. Thus, aminoglycoside induction of mexXY is a response to membrane damage and activation of the AmgRS two-component system.

Quality of life in children with primary antibody deficiency

Primary antibody deficiency disorders (PADs) can have an excellent outlook if diagnosed early and treated appropriately, but require lifelong treatment with immunoglobulin replacement. Some carry risks of inflammatory complications even with optimal treatment. Quality of life (QoL) and the psychological impact of PADs has been relatively little studied, particularly in children. The purpose of this study was to evaluate QoL and psychological impact in a large group of children affected by a range of PADs, as well as a group with transient hypogammaglobulinemia of infancy (THI). Both parental and, where appropriate, child ratings, were collected using standardised questionnaires (PedsQL and SDQ). Higher rates of psychological difficulties, particularly emotional and peer-relationship difficulties were found in children with PAD when compared with healthy controls. Quality of life was poorer than in healthy controls, and also worse than in children affected by diabetes mellitus. Variations in QoL and the degree of psychological difficulties were found between specific diagnostic groups, with children affected by THI being amongst those with the lowest scores for QoL. Further studies are needed to corroborate and extend these findings, but this study confirms previous findings that primary antibody deficiency has a significant impact on quality of life and psychological well-being, and additionally suggests that the impact varies according to severity of the underlying condition. For those with significant difficulties psychological intervention at an early stage may be beneficial.

Citrate-mediated iron uptake in Pseudomonas aeruginosa: involvement of the citrate-inducible FecA receptor and the FeoB ferrous iron transporter

In an attempt to identify components of a ferric citrate uptake system in Pseudomonas aeruginosa, a mutant library of a siderophore-deficient strain (IA614) was constructed and screened for defects in citrate-promoted growth in an Fe-restricted medium. A mutant disrupted in gene PA3901, encoding a homologue of the outer-membrane ferric citrate receptor, FecA, of Escherichia coli (FecA(E.c.)), was recovered and shown to be deficient in citrate-promoted growth and citrate-mediated Fe uptake. A mutant disrupted in gene PA4825, encoding a homologue of the MgtA/MgtB Mg2+ transporters in Salmonella enterica, was similarly deficient in citrate-promoted growth, though this was due to a citrate sensitivity of the mutant apparently resulting from citrate-promoted acquisition of Fe2+ and resultant oxidative stress. Consistent with citrate delivering Fe to cells as Fe2+, a P. aeruginosa mutant lacking the FeoB Fe2+ transporter homologue, PA4358, was compromised for citrate-promoted growth in Fe-restricted medium and showed markedly reduced citrate-mediated Fe uptake. Subsequent elimination of two Fe3+ transporter homologues, PA5216 and PA4687, in the feoB mutant failed to further compromise citrate-promoted growth or Fe uptake, though the additional loss of pcoA, encoding a periplasmic ferroxidase implicated in Fe2+ acquisition, completely abrogated citrate-mediated Fe uptake. Fe acquisition mediated by other siderophores (e.g. pyoverdine) was, however, unaffected in the quadruple knockout strain. These data indicate that Fe delivered to P. aeruginosa by citrate is released as Fe2+, probably in the periplasm, prior to its transport into cells via Fe transport components.

Circulating and placental endoglin concentrations in pregnancies complicated by intrauterine growth restriction and preeclampsia

Inadequate trophoblast invasion and spiral artery remodeling leading to poor placental perfusion and hypoxia are believed to underlie preeclampsia (PE) and intrauterine growth restriction (IUGR). Recent studies implicate increased circulating endoglin as a contributor to the pathogenesis of PE. The objective of this study was to determine whether placental and circulating endoglin concentrations are altered in pregnancies complicated by intrauterine growth restricted (IUGR) infants and to address the role of hypoxia on the regulation of placental endoglin. We analyzed 10 placentas each from normal pregnant (NP), PE, and IUGR subjects. Endoglin levels were 2.5-fold higher in preeclamptic placentas compared to NP (15.4+/-2.6 versus 5.7+/-1.0, p<0.01). In contrast, endoglin levels were similar in NP and IUGR placentas (5.7+/-1.0 vs 5.9+/-1.1, p=NS). Placentas from pregnancies with both PE and IUGR exhibited endoglin levels comparable to the PE group and significantly different from normotensive pregnancies with and without IUGR pregnancies (mean 14.9+/-4.0, n=9, p=0.013). Soluble endoglin concentrations in maternal plasma were comparable in NP and IUGR, but higher in women with PE (n=10 per group, p<0.05). Despite a 2-fold increase in hypoxia inducible factor, HIF-1alpha, we did not observe endoglin upregulation in NP, PE, or IUGR placental villous explants exposed to hypoxia (2% oxygen). In contrast to PE, placental or circulating endoglin is not increased in normotensive women delivering small, asymmetrically grown (IUGR) infants at term. The placentas of women with IUGR appear to be fundamentally different from PE women with respect to endoglin, despite the proposed common pathology of deficient trophoblast invasion/spiral artery remodeling and poor placental perfusion.

Effect of pulsed dexamethasone therapy on tolerance of intravenously administered lipids in extremely low birth weight infants

We investigated the effect of dexamethasone on parenteral lipid tolerance in 7-day-old extremely low birth weight infants (n = 28) in a randomized, double-blind trial. Serum triglycerides were measured before and after 3 days of dexamethasone or placebo treatment. Infants treated with dexamethasone responded with higher triglyceride concentrations and greater sensitivity to incremental increases in the intravenous lipid dose.

Post-traumatic stress disorder in children and adolescents following road traffic accidents

BACKGROUND

Post-traumatic stress disorder (PTSD) can be a persistent and disabling psychiatric disorder. There is little systematic research into the psychiatric consequences of road traffic accidents (RTAs) in children and adolescents.

METHOD

A consecutive sample of 8-16-year-olds attending an accident and emergency department following RTAs were screened for PTSD. Potential cases and their parent(s) were interviewed with semi-structured research instruments about six weeks and six months after the accident.

RESULTS

Fifty-three (45%) of the 119 subjects fell above PTSD cut-off on the Frederick's Reaction Index. Thirty-three (75%) of the 44 cases met DSM-IV criteria for PTSD. In half of these other psychiatric disorders were present, including major depressive disorder and anxiety disorders. Being female, involvement in car accidents and pre-existing depression and anxiety were associated with developing PTSD. Seventeen per cent of the sample continued to be symptomatic six months after the accident.

CONCLUSIONS

PTSD is a common consequence of RTAs. Liaison with accident and emergency departments would enhance the early detection and follow-up of children at risk of developing PTSD.