Pathogens of Dikerogammarus haemobaphes regulate host activity and survival, but also threaten native amphipod populations in the UK

Dikerogammarus haemobaphes is a non-native amphipod in UK freshwaters. Studies have identified this species as a low-impact invader in the UK, relative to its cousin Dikerogammarus villosus. It has been suggested that regulation by symbionts (such as Microsporidia) could explain this difference in impact. The effect of parasitism on D. haemobaphes is largely unknown. This was explored herein using 2 behavioural assays measuring activity and aggregation. First, D. haemobaphes were screened histologically post-assay, identifying 2 novel viruses (D. haemobaphes bi-facies-like virus [DhbflV], D. haemobaphes bacilliform virus [DhBV]), Cucumispora ornata (Microsporidia), Apicomplexa, and Digenea, which could alter host behaviour. DhBV infection burden increased host activity, and C. ornata infection reduced host activity. Second, native invertebrates were collected from the invasion site at Carlton Brook, UK, and tested for the presence of C. ornata. PCR screening identified that Gammarus pulex and other native invertebrates were positive for C. ornata. The host range of this parasite, and its impact on host survival, was additionally explored using D. haemobaphes, D. villosus, and G. pulex in a laboratory trial. D. haemobaphes and G. pulex became infected by C. ornata, which also lowered survival rate. D. villosus did not become infected. A PCR protocol for DhbflV was also applied to D. haemobaphes after the survival trial, associating this virus with decreased host survival. In conclusion, D. haemobaphes has a complex relationship with parasites in the UK environment. C. ornata likely regulates populations by decreasing host survival and activity, but despite this benefit, the parasite threatens susceptible native wildlife.

A strategy for monitoring and evaluating massive open online courses

We argue that the complex, innovative and adaptive nature of Massive Open Online Course (MOOC) initiatives poses particular challenges to monitoring and evaluation, in that any evaluation strategy will need to follow a systems approach. This article aims to guide organizations implementing MOOCs through a series of steps to assist them in developing a strategy to monitor, improve, and judge the merit of their initiatives. We describe how we operationalise our strategy by first defining the different layers of interacting agents in a given MOOC system. We then tailor our approach to these different layers. Specifically, a two-pronged approach was developed, where we suggest that individual projects be assessed through performance monitoring; assessment criteria for which would be defined at the outset to include coverage, participation, quality and student achievement. In contrast, the success of an overall initiative should be considered within a more adaptive, emergent evaluation inquiry framework. We present the inquiry framework we developed for MOOC initiatives, and show how this framework might be used to develop evaluation questions and an assessment methodology. We also define the more fixed indicators and measures for project performance monitoring. Our strategy is described as it was developed to inform the evaluation of a MOOC initiative at the University of Cape Town (UCT), South Africa.

Shape coexistence in the neutron-deficient even-even (182-188)Hg isotopes studied via coulomb excitation

Coulomb-excitation experiments to study electromagnetic properties of radioactive even-even Hg isotopes were performed with 2.85  MeV/nucleon mercury beams from REX-ISOLDE. Magnitudes and relative signs of the reduced E2 matrix elements that couple the ground state and low-lying excited states in Hg182-188 were extracted. Information on the deformation of the ground and the first excited 0+ states was deduced using the quadrupole sum rules approach. Results show that the ground state is slightly deformed and of oblate nature, while a larger deformation for the excited 0+ state was noted in Hg182,184. The results are compared to beyond mean field and interacting-boson based models and interpreted within a two-state mixing model. Partial agreement with the model calculations was obtained. The presence of two different structures in the light even-mass mercury isotopes that coexist at low excitation energy is firmly established.

The impact of regional anaesthesia on outcome: a patient's perspective

Peripheral nerve catheters are being used increasingly to manage acute pain. Whilst acknowledged as effective, their broader implications for patient outcome are less clear. In this case report, we describe the way in which not only was the pain management of an ischaemic leg successful via a sciatic nerve catheter, but decision-making around this strategy affected outcome.

Self-rated psychosocial consequences and quality of life in the acute porphyrias

A battery of self-report psychosocial measures was mailed to 116 patients who had been referred for clinical management (clinic attenders) or laboratory diagnosis (non-clinic attenders) to the London Supraregional Assay Service Centre for Porphyria over the past decade and who tested positive for porphyria. Usable replies were received from 81 (70%) patients. Our interest focused on the prevalence of psychosocial symptoms in acute porphyrias and the perceived effects of porphyria on quality of life and patient experience. Research questions examined included (i), lifestyle factors; (ii) life events; (iii) mental health; (iv) general health; and (v) perceptions of illness of patients receiving specialist clinical management compared to respondents referred for diagnostic investigations, between patients with latent or manifest symptomology and between patients with different types of porphyria. Patients with porphyria have an impaired quality of life, particularly manifest cases, compared to controls and to diabetic patients. Depression, and particularly anxiety, is more common than in the general population or general medical outpatient attenders. Quality oflife is lower in acute intermittent porphyria (AIP) than in other forms of porphyria and a significant number of patients had major life event consequences, e.g. failure to secure, or loss of, employment, limitation of family size. Patients attending a clinic providing specialist porphyria advice, management and counselling received some perceived lifestyle benefits.

Evidence that NADP+ is the physiological cofactor of ADP-L-glycero-D-mannoheptose 6-epimerase

ADP-L-glycero-D-mannoheptose 6-epimerase is required for lipopolysaccharide inner core biosynthesis in several genera of Gram-negative bacteria. The enzyme contains both fingerprint sequences Gly-X-Gly-X-X-Gly and Gly-X-X-Gly-X-X-Gly near its N terminus, which is indicative of an ADP binding fold. Previous studies of this ADP-l-glycero-D-mannoheptose 6-epimerase (ADP-hep 6-epimerase) were consistent with an NAD(+) cofactor. However, the crystal structure of this ADP-hep 6-epimerase showed bound NADP (Deacon, A. M., Ni, Y. S., Coleman, W. G., Jr., and Ealick, S. E. (2000) Structure 5, 453-462). In present studies, apo-ADP-hep 6-epimerase was reconstituted with NAD(+), NADP(+), and FAD. In this report we provide data that shows NAD(+) and NADP(+) both restored enzymatic activity, but FAD could not. Furthermore, ADP-hep 6-epimerase exhibited a preference for binding of NADP(+) over NAD(+). The K(d) value for NADP(+) was 26 microm whereas that for NAD(+) was 45 microm. Ultraviolet circular dichroism spectra showed that apo-ADP-hep 6-epimerase reconstituted with NADP(+) had more secondary structure than apo-ADP-hep 6-epimerase reconstituted with NAD(+). Perchloric acid extracts of the purified enzyme were assayed with NAD(+)-specific alcohol dehydrogenase and NADP(+)-specific isocitric dehydrogenase. A sample of the same perchloric acid extract was analyzed in chromatographic studies, which demonstrated that ADP-hep 6-epimerase binds NADP(+) in vivo. A structural comparison of ADP-hep 6-epimerase with UDP-galactose 4-epimerase, which utilizes an NAD(+) cofactor, has identified the regions of ADP-hep 6-epimerase, which defines its specificity for NADP(+).

Bullous dermatoses in end-stage renal failure: porphyria or pseudoporphyria?

Bullous dermatoses (BD) are well recognized in patients with end-stage renal disease (ESRD). It is important to distinguish pseudoporphyria (porphyrin accumulation due to decreased clearance) from true porphyrias, particularly those in which acute neurological attacks may occur. Investigation of the dialysis patient poses practical diagnostic difficulties because urinary porphyrin profiles are not available. We describe a patient on continuous ambulatory peritoneal dialysis (CAPD) with several recognized causative factors for porphyria cutanea tarda (PCT). The patient presented with a blistering photosensitive rash. We highlight the importance of investigating anuric patients with fractionation of both fecal and plasma porphyrins. Plasma porphyrins were grossly elevated (345 nmol/L; reference range, <13), whereas plasma porphyrins in a control group of CAPD patients without blistering rashes were only minimally elevated (mean, 23.9 nmol/L; SD, 11.0; n = 9). Fractionation of fecal porphyrins by high-performance liquid chromatography (HPLC) yielded a pattern typical of PCT. In addition to the contributory factors for PCT that were present, it is possible that porphyrin accumulation secondary to renal failure played a role in the expression of her disease. Patients with ESRD presenting with BD require careful evaluation, including fractionation of fecal porphyrins.

Determination of the structure of seleno-methionine-labelled hydroxymethylbilane synthase in its active form by multi-wavelength anomalous dispersion

The enzyme hydroxymethylbilane synthase (HMBS, E.C. 4.3.1.8) catalyzes the conversion of porphobilinogen into hydroxymethylbilane, a key intermediate for the biosynthesis of heme, chlorophylls, vitamin B12 and related macrocycles. The enzyme is found in all organisms, except viruses. The crystal structure of the selenomethionine-labelled enzyme ([SeMet]HMBS) from Escherichia coli has been solved by the multi-wavelength anomalous dispersion (MAD) experimental method using the Daresbury SRS station 9.5. In addition, [SeMet]HMBS has been studied by MAD at the Grenoble ESRF MAD beamline BM14 (BL19) and this work is described especially with respect to the use of the ESRF CCD detector. The structure at ambient temperature has been refined, the R factor being 16.8% at 2. 4 A resolution. The dipyrromethane cofactor of the enzyme is preserved in its reduced form in the crystal and its geometrical shape is in full agreement with the crystal structures of authentic dipyrromethanes. Proximal to the reactive C atom of the reduced cofactor, spherical density is seen consistent with there being a water molecule ideally placed to take part in the final step of the enzyme reaction cycle. Intriguingly, the loop with residues 47-58 is not ordered in the structure of this form of the enzyme, which carries no substrate. Direct experimental study of the active enzyme is now feasible using time-resolved Laue diffraction and freeze-trapping, building on the structural work described here as the foundation.

Two crystal structures towards the discotic columnar mesophase of (1,4,8,11,15,18,22,25-octahexylphthalocyaninato)nickel. Erratum

The low-temperature apparatus used in this work [Helliwell, Deacon, Moon, Powell & Cook, Acta Cryst. (1997), B53, 231–240] was the Oxford Cryosystems Cryostream, and not as stated a cryo-cooling system manufactured by Oxford Instruments. Also, on p. 235, lines 8–10, right-hand column, should read '...for molecule (2), whilst two are approximately perpendicular to it. .. For molecule (1)...'. © 1997 International Union of Crystallography Printed in Great Britain - all rights reserved Acta Crystallographica Section B ISSN 0108–7681 © 1997

Two Crystal Structures Towards the Discotic Columnar Mesophase of (1,4,8,11,15,18,22,25-Octahexylphthalocyaninato)nickel

(1,4,8,11,15,18,22,25-Octahexylphthalocyaninato)nickel is a thermotropic liquid crystal, undergoing a transition to a discotic columnar mesophase at 418 K. Its crystals are weakly diffracting needles. Single-crystal X-ray diffraction studies at 103 K, using intense synchrotron radiation of wavelength 0.504 Å at Station F2, CHESS and the `Princeton 1k' CCD area detector, and at 295 K using a Cu Kα rotating anode diffractometer, have respectively shown that the symmetry of the crystals is increased from primitive monoclinic (space group P21/n) to C-centred monoclinic (space group C2/c) when the temperature is raised. Solution of the structure at each temperature shows that the increase in symmetry at 295 K arises from slight movement of the molecules, as well as increased thermal motion of the hexyl groups, and small conformational changes in these groups, indicating the first stage of the transition to the discotic columnar mesophase, when the hexyl groups are thought to become completely mobile. The quality of the refinement of the structure is indicative of what can now be realized by employing multipole wiggler synchrotron radiation and a CCD area detector, as well as cryocooling, for difficult small molecule samples. The temperature of the space group transition was determined at the Daresbury SRS, on Station 7.2, using a CCD detector to monitor an area of the diffraction pattern, whilst varying the temperature systematically. A gradual appearance of spots for h + k = 2n + l occurred between 205 and 195 K. Tests were also made using an image plate system at 195 and 293 K, which confirmed the transition from primitive to C-centred lattice symmetry with temperature. No other changes were apparent on the CCD or IP detectors.

Osteoarthritis of the knee in retired, elite Australian Rules footballers

OBJECTIVE

To determine the functional and radiological status of knee joints of retired Australian Rules footballers compared with those of active community members.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Fifty retired elite footballers aged 34-85 years (mean, 53.7 years; SD, 11.4) from four AFL clubs and 50 age-matched controls (35-79 years; mean, 55.7 years; SD, 12.4) who had played no contact sport since their teenage years.

MAIN OUTCOME MEASURES

Severity of knee functional osteoarthritis as determined by a questionnaire, and assessment of osteoarthritis by posteroanterior weight-bearing radiographs taken of both knees of each participant in 45-degree flexion.

RESULTS

After adjusting for age, height, weight and body mass index, footballers had a significantly greater prevalence (P < 0.0001) and severity (P < 0.05) of functional and radiological osteoarthritis than controls. Footballers with a history of intraarticular ligamentous and/or meniscal injury (Group 1) had a greater risk of functional osteoarthritis (P = 0.002) and radiological (P = 0.067) osteoarthritis than those with a history of collateral ligament injury or no injury (Group 2). Compared with controls, the odds of developing moderate to severe levels of functional and radiological osteoarthritis were 6.9 times (95% CI, 1.6-29.7; P = 0.01) and 105.0 times (95% CI, 11.8-931.8; P < 0.0001), respectively, those in Group 1 footballers and 3.6 times (95% CI, 0.8-16.2; P = 0.10) and 17.7 times (95% CI, 2.2-146.2; P = 0.0075), respectively, those in Group 2 footballers.

CONCLUSIONS

Elite Australian Rules footballers have a significant risk of both functional and radiological osteoarthritis, and a history of intra-articular ligament or meniscal injury increases this risk.

Trends and challenges in experimental macromolecular crystallography

Macromolecular X-ray crystallography underpins the vigorous field of structural molecular biology having yielded many protein, nucleic acid and virus structures in fine detail. The understanding of the recognition by these macromolecules, as receptors, of their cognate ligands involves the detailed study of the structural chemistry of their molecular interactions. Also these structural details underpin the rational design of novel inhibitors in modern drug discovery in the pharmaceutical industry. Moreover, from such structures the functional details can be inferred, such as the biological chemistry of enzyme reactivity. There is then a vast number and range of types of biological macromolecules that potentially could be studied. The completion of the protein primary sequencing of the yeast genome, and the human genome sequencing project comprising some 105proteins that is underway, raises expectations for equivalent three dimensional structural databases.

Suspended silt concentrations in the lower Olifants River (Mpumalanga) and the impact of silt releases from the Phalaborwa Barrage on water quality and fish survival

Silt loads in the Olifants and Sabie river systems inside the Kruger National Park, were monitored by collecting water samples every consecutive week for a period of 20 months. The variation in silt concentration, changes in selected physico-chemical water quality variables and fish mortalities during flushing (i.e. release of silt, by sluicing) of the Phalaborwa Barrage, were also monitored. The Olifants River inside the Kruger National Park carried high silt loads in summer; in the dry season the suspensoid load was greatly reduced. A similar pattern was observed in the Sabie River, but the silt loads were generally lower. It was apparent that silt loads released from the Phalaborwa Barrage led to large variations in the natural silt loads of the Olifants River. These increased amounts of silt (25 000 mg/1 to >70 000 mg/1) caused drastic reductions in the dissolved oxygen concentration of the water, ranging from >6 mg/1 to 0 mg/1. Depending on the severity and duration of the flushing, fish succumb to such silt loads. These findings, as well as published information, indicate that the management strategy of flushing to improve storage capacity is ecological unacceptable. It is therefore suggested that the use of the Phalaborwa Barrage as a future reservoir should be critically re-evaluated.

Variations in selected water quality variables and metal concentrations in the sediment of the lower Olifants and Selati rivers, South Africa

A survey of the water and sediment quality of the lower Olifants River and lower Selati River was carried out. Metal concentrations (Cr, Cu, Fe, Mn, Ni, Pb, Sr and Zn) in the water and sediment, as well as the physical and chemical characteristics of the water were determined over a two-year period (April 1990 - February 1992). The water quality of the lower Selati River, which flows through the Phalaborwa area, was found to be influenced by the mining and industrial activities in the area. It was also the case with the lower Olifants River after the Selati-Olifants confluence, although the concentrations of most variables did decrease from the western side of the Kruger National Park to the eastern side due to dilution of the water by tributaries of the Olifants River. Variables of special concern were sodium, fluoride. chloride, sulphate, potassium, the total dissolved salts and the metal concentrations (except strontium). The water quality of the Selati River in the study area is a great cause of concern and a further degradation thereof cannot be afforded.

Which hormone tests for the diagnosis of polycystic ovary syndrome?

OBJECTIVE

To assess the frequency of abnormal values for hormone measurements commonly used in the biochemical diagnosis of polycystic ovary syndrome (PCOS).

DESIGN

Hormone measurements in 63 unselected women with clinical and ultrasound diagnosis of PCOS attending gynaecological and general endocrine clinics in a District General Hospital were compared with those from a group of 20 normal ovulatory controls in the early follicular phase of their cycles.

MEASUREMENTS

Serum levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), LH/FSH ratio, total testosterone, derived free testosterone, sex hormone binding globulin, androstenedione, and dehydroepiandrosterone (DHEA) were measured by radioimmunoassays. LH and FSH measured by two different assays.

RESULTS

The mean serum LH and LH/FSH ratio were significantly (P less than 0.01) higher in the women with PCOS compared with the normal group, but these two measurements were in the abnormal range for only 35% and 41-44%, respectively. Absolute gonadotrophin values were significantly different using the two assay methods, which employed the same reference preparation as standard. Mean serum total testosterone concentration was significantly higher in the PCOS group and was the most frequently (70%) abnormal biochemical marker for PCOS. Sex hormone binding globulin (SHBG) did not differ significantly between the two groups but showed a negative correlation with body mass index in women with PCOS. The combination of SHBG and testosterone to derive a free testosterone value did not further aid the biochemical diagnosis of PCOS. Androstenedione was significantly higher in the PCOS group than in the control group, with a frequency of 53%. There was no significant difference in DHEA-S between the two groups.

CONCLUSION

When typical ovarian ultrasound appearances plus the clinical features of oligomenorrhea and/or hirsuitism were used to define PCOS total testosterone was the best single hormonal marker of the condition. Testosterone, androstenedione or LH, either alone or in combination, were raised in 86% of women with PCOS and these should be the definitive hormonal tests. Using LH/FSH ratio as a biochemical criterion for diagnosis of PCOS should be abandoned because of its low sensitivity. To be of value the normal range for all hormones should be precisely defined in a group of regularly ovulating women in the early follicular phase of the cycle for the assay used in each laboratory.