Characteristics of and risk factors for contact lens-related microbial keratitis in a tertiary referral hospital

AIM

A retrospective case-control study was conducted at a tertiary referral hospital to determine the characteristics of and risk factors for contact lens (CL) related presumed microbial keratitis.

METHODS

Two hundred and ninety-one cases of presumed microbial keratitis were retrospectively identified over a 2-year period. Records were reviewed for a history of CL wear and, where identified, CL, demographic, and clinical data were collected. Lens wearing controls (n=186) were identified by a community telephone survey. Multiple logistic regression estimated risk factors for infection and vision loss.

RESULTS

Ninety-nine (34%) new cases of presumed microbial keratitis were associated with CL wear. Overnight soft CL use was associated with an increased risk of infection compared to daily disposable CL wear (odds ratio (OR): 8.03, 95% confidence interval (CI): 1.82-35.46). Compared with older CL wearers, 15-24 year olds had a 3.5 times greater risk of infection (OR, 95% CI: 1.7-7.4). Of the 84 cases with available data, 24 (29%) lost two or more lines of best-corrected visual acuity. Delaying treatment by 49-72 h had a 4.5 times (OR, 95% CI: 1.4-14.9) greater risk of visual loss compared to seeking treatment early. Of the 99 cases of infection, 88 were scraped and 78% (69/88) of these returned a positive culture. Gram-positive bacteria were the predominant causative organisms.

CONCLUSION

Overnight use of CL and youth carry a greater risk of infection. Practitioners should reinforce the importance of proper CL care at all times, and early presentation following the onset of symptoms.

FSH biosensor to detect postpartum ovarian recrudescence

Preliminary evidence of FSH suppression as a marker of postpartum ovarian recrudescence is presented. Falling FSH concentration in response to ovarian follicular estrogenic secretory activity apparently signals the reestablishment of menstrual cycles. We propose to investigate further this phenomenon with the development of a portable FSH biosensor. The FSH biosensor design is based on SPR and biological thin-film technologies and is incorporated as a key element of the fertility information appliance. It is possible that the device could be a useful natural family planning tool, especially during the return to fertility after childbirth.

Surface engineering of artificial heart valve disks using nanostructured thin films deposited by chemical vapour deposition and sol-gel methods

Pyrolytic carbon (PyC) is widely used in manufacturing commercial artificial heart valve disks (HVD). Although PyC is commonly used in HVD, it is not the best material for this application since its blood compatibility is not ideal for prolonged clinical use. As a result thrombosis often occurs and the patients are required to take anti-coagulation drugs on a regular basis in order to minimize the formation of thrombosis. However, anti-coagulation therapy gives rise to some detrimental side effects in patients. Therefore, it is extremely urgent that newer and more technically advanced materials with better surface and bulk properties are developed. In this paper, we report the mechanical properties of PyC-HVD, i.e. strength, wear resistance and coefficient of friction. The strength of the material was assessed using Brinell indentation tests. Furthermore, wear resistance and coefficient of friction values were obtained from pin-on-disk testing. The micro-structural properties of PyC were characterized using XRD, Raman spectroscopy and SEM analysis. Also in this paper we report the preparation of freestanding nanocrystalline diamond films (FSND) using the time-modulated chemical vapour deposition (TMCVD) process. Furthermore, the sol-gel technique was used to uniformly coat PyC-HVD with dense, nanocrystalline-titanium oxide (nc-TiO2) coatings. The as-grown nc-TiO2 coatings were characterized for microstructure using SEM and XRD analysis.

A simple processing method allowing comparison of renal enhancing volumes derived from standard portal venous phase contrast-enhanced multidetector CT images to derive a CT estimate of differential renal function with equivalent results to nuclear medicine quantification

As iodinated contrast medium is cleared by glomerular filtration, it should be possible to apply the same principles utilized in radionuclide studies to derive differential renal function by comparison of enhancing renal volumes derived from contrast enhanced multidetector CT (CEMDCT). Having established a technique iteratively which appeared successful, a retrospective study was performed using 25 consecutive patients with a wide range of urological conditions who had undergone both CEMDCT, including the renal area in the portal venous phase, and nuclear medicine (NM) assessment of renal function with no urological intervention between the studies. Proprietary volume software was used to quantify the volume and attenuation of each kidney, the products of which (after subtraction of soft tissue attenuation derived from a region of interest over psoas) gave right and left enhancing renal volumes. The contribution by each kidney as a percentage of total renal enhancing tissue was derived. Comparison with NM studies resulted in excellent correlation of relative renal function by CEMDCT and NM assessments having a regression of near unity and a Pearson's correlation coefficient of 0.96. Bland Altman and Passing Bablock tests confirmed good agreement between the two methods with no bias. This is a simple, practicable processing technique using standard portal venous phase CEMDCT images to quantify differential function. This technique may allow a one-stop CT assessment of both anatomy and function.

The impact of psoriasis guidelines on appropriateness of referral from primary to secondary care: a randomized controlled trial

BACKGROUND

Most patients with psoriasis have limited disease which can be managed effectively in primary care. There is a marked variation in the frequency of referrals between practices reflecting, in part, inadequate training of general practitioners (GPs) in the management of psoriasis.

OBJECTIVES

To assess the effectiveness of guidelines and training sessions on the management of psoriasis in reducing inappropriate referrals from primary care.

METHODS

Patients aged 18 years or over with psoriasis were eligible for the cluster-randomized, randomized controlled trial if they were referred by their GP between 9 September 2002 and 31 December 2003 to one of four hospital dermatology departments in Greater Manchester, North-West England. All GPs from 165 health centres were invited to a lecture by a local dermatologist on the diagnosis and management of psoriasis. Health centres in the intervention arm received guidelines on the management of psoriasis in primary care, developed by local dermatologists, supplemented by the offer of a practice-based nurse-led training session; those in the control arm received neither guidelines nor training sessions.

RESULTS

Eighty-two health centres were randomized to the intervention arm and 83 to the control arm. Outcome data were available for 188 of the 196 eligible patients referred during the study period. Patients in the intervention arm were significantly more likely to be appropriately referred in comparison with patients in the control arm [difference = 19.1%; odds ratio (OR) 2.47; 95% confidence interval (CI) 1.31-4.68; intracluster correlation coefficient (ICC) = 0]. Only 25 (30%) health centres in the intervention arm took up the offer of training sessions. There was no significant difference in outcome between health centres in the intervention arm that received a training session and those that did not (OR 1.28, 95% CI 0.50-3.29, ICC = 0).

CONCLUSIONS

Dissemination of guidelines on the management of psoriasis in primary care can significantly enhance the appropriateness of referral of patients to secondary care.

External factors in the development of cataract

AIMS

To provide an update on the risk factors for cataract development.

METHODS

Review of the literature.

RESULTS

Age and heredity are the most important risk factors associated with the different types of cataract. While the hereditary component is self-explanatory, increasing age serves as a surrogate for a number of potential external risk factors, the effect of which is cumulative. Identification of the risk factors that have a causal effect on cataract development may provide means for cataract prevention. There are only a few risk factors that satisfy the criteria for causal effect: smoking, which results in the increased risk of nuclear cataract, excessive UV-B exposure and diabetes that increase the risk of cortical cataract, and steroidal treatment, diabetes and ionising radiation that lead to the formation of posterior subcapsular opacity. The effect of medications on cataract development requires further study, since the effect of the diseases should be distinguished from that of treatment. 'Stop Smoking' and 'UV-B protection' campaigns are gaining momentum as preventative measures, while the attempts to actively prevent cataract with antioxidants have not been successful. Cataract research has been facilitated lately by improvements of precision and standardisation in measuring lens opacities. However, measurement precision on its own cannot give us a solution to this problem.

CONCLUSION

The major studies repeatedly measure the exposure to the traditional health hazards, while the missing parts in the equation are those risk factors that we do not know about and therefore do not measure. New approaches and new hypotheses are needed.

Environmental assessment of mercury contamination from the Rwamagasa artisanal gold mining centre, Geita District, Tanzania

This study presents the results of an environmental assessment of mercury (Hg) contamination in the Rwamagasa artisanal gold mining area, northwest Tanzania, and the potential downstream dispersion along the River Malagarasi to Lake Tanganyika. At the time of sampling, generally low concentrations of Hg (<0.05 mg/kg) occurred in most cultivated soils although higher Hg (0.05-9.2 mg/kg) was recorded in urban soils and vegetable plot soils where these are impacted by Hg-contaminated water and sediment derived from mineral processing activities. Hg in vegetable and grain samples is mostly below the detection limit of 0.004 mg/kg Hg, apart from 0.007 and 0.092 mg/kg Hg in two yam samples and 0.011 to 0.013 mg/kg Hg in three rice samples. The standardized (i.e., standardized to 10 cm length) Hg concentrations in Clarias spp. increase from about 0.01 mg Hg/kg for the River Malagarasi delta to 0.07, 0.2, and 1.6 mg/kg, respectively, for the Rwamagasa 'background', moderately and most contaminated sites. For piscivorous (Lates, Brycinus, and Hydrocynus spp.), insectivorous (Barbus spp.), and planktivorous (Haplochromis spp.) fish species, the 10-cm standardized Hg concentrations increase from about 0.006 mg/kg for the River Malagarasi-Lake Tanganyika area to 0.5 and 3.5 mg/kg, respectively, for the Rwamagasa moderately and most contaminated sites. The low concentrations of Hg in fish from the Malagarasi River delta and Lake Tanganyika indicate that Hg contamination from the Rwamagasa area does not have a readily discernible impact on the biota of Lake Tanganyika. Many of the fish samples from Rwamagasa exceed guidelines for human consumption (0.5 mg/kg) as well as the WHO recommended limit for vulnerable groups (0.2 mg/kg). Tissue total Hg (THg) of all fish collected from the River Malagarasi-Lake Tanganyika subarea is well below these guidelines. Potential human exposure through consumption of 300 g/day of rice grown on Hg-contaminated soils is 5.5 microg/week. Consumption of 250 g Nile perch (Lates spp.), 500 g tilapia (Oreochromis spp.), and 250 g of catfish (Clarias spp.) each week would result in an intake of 65 microg Hg/week for people consuming only fish from the Mara and Mwanza regions of Lake Victoria and 116 microg Hg/week for people in the Rwamagasa area consuming tilapia and Nile perch from Lake Victoria and catfish from mining-impacted streams. This is lower than the Provisional Tolerable Weekly Intake (PTWI) of 300 microg for Hg in the diet set by the WHO and the FAO. Inadvertent ingestion of soil containing 9 mg Hg/kg at a rate of 80 mg/day would give an additional estimated weekly intake of 5 microg THg, whereas the persistent and purposeful consumption of soil (geophagia) at a rate of 26 g soil/day would produce an additional chemical exposure of 230 microg Hg/day.

Bioaccessibility of arsenic in soils developed over Jurassic ironstones in eastern England

Jurassic ironstones outcropping over parts of eastern England give rise to soils with arsenic concentrations in excess of the UK soil guideline value of 20 mg kg(-1) for residential areas. Total arsenic concentrations were determined for 73 ironstone derived soils and bioaccessible arsenic determined using an in vitro physiologically based extraction test. The bioaccessible arsenic concentration for these soils was found to be well below the soil guideline value with a mean concentration of 4 mg kg(-1) and a range of 2-17 mg kg(-1). The bioaccessible fraction ranges from 1.2 to 33%. Data from a sequential extraction test based on the use of aqua regia as the main extractant is presented for a subset of 20 of the soils. Chemometric data reduction is used to demonstrate that the bioaccessible arsenic is mainly contained within calcium iron carbonate (sideritic) assemblages and only partially iron aluminosilicates, probably berthierine, and iron oxyhydroxide phases, probably goethite. It is suggested that the bulk of the non-bioaccessible arsenic is bound up with less reactive iron oxide phases.

Evaluation of the Paediatric Index of Mortality in children managed on adult intensive care units

OBJECTIVE

To evaluate the performance of the Paediatric Index of Mortality (PIM) in children cared for in adult intensive care units (ICUs) in district general hospitals in the South West Region of England.

DESIGN AND SETTING

An observational survey of all children admitted to adult ICUs in 15 district general hospitals between November 2000 and August 2002. For comparison, data were also collected from the regional paediatric ICUs between November 2000 and March 2002.

RESULTS

Data were collected from 374 children admitted to adult ICUs and 850 children admitted to the regional paediatric ICU. There were significant differences in the patient characteristics between the two groups. In the adult ICU paediatric population, PIM discriminated well between death and survival (Az ROC = 0.96 (95% confidence interval, 0.93 to 0.99)) and calibrated well across deciles of risk (goodness of fit chi2 = 4.55 (8 df), p = 0.8).

CONCLUSIONS

PIM performs well as a risk adjustment method in children whose entire care remains in the adult ICU of a district general hospital. This is important should the Paediatric Intensive Care Audit Network (PICAnet) decide to extend its data collection beyond paediatric intensive care units to other units caring for critically ill children.

Prolonged use of oral contraception before a planned pregnancy is associated with a decreased risk of delayed conception

BACKGROUND

The aim of this study was to investigate the association of total duration of oral contraceptive usage with time to conception.

METHODS

This was a prospective study of 8497 planned pregnancies drawn from a population that recruited 85% of eligible couples in South-West England who were expecting a baby in a 21 month period. Self-completion questionnaires were administered at 18 weeks gestation to ascertain parity, paternity, co-habitation, use of the contraceptive pill, smoking and alcohol status, educational achievement, height, weight and time taken to conceive. Logistic regression was used to identify factors independently related to conception in < or =12 months.

RESULTS

Of the participants, 74% conceived in < or =6 months, 14% in 6-12 months and 12% after 1 year. Previous prolonged oral contraceptive usage was statistically significantly associated with a decreased risk of delayed conception. Prolonged use of oral contraception was also associated with improved fecundity independent of other factors. Selection bias due to particularly fertile women using oral contraceptives is unlikely because similar odds ratios were calculated for nulligravid women.

CONCLUSIONS

Women who have prolonged use of oral contraceptives might be reassured that they will not be disadvantaged in terms of time taken to achieve conception.

Pterygium in Australia: a cost of illness study

PURPOSE

The aim of this report was to describe the number of Australians affected by pterygium in recent years, treatment options, number of treatment encounters and costs of treatment.

METHOD

A review of published literature was conducted to identify the prevalence of pterygium in Australian populations. Costs of primary care were based on national general practitioner (GP) survey data. Costs of surgical intervention were based on Health Insurance Commission claims data and Australian Institute of Health and Welfare National Hospital Morbidity Data.

RESULTS

Pterygium occurs in 1.1% of Australians. It is more prevalent in populations with higher exposure to ultraviolet radiation, and older men (occurring in 12% of males over 60 years). The estimated annual number of GP contacts was 58,900. Forty per cent of primary care contacts for pterygium were referred to an ophthalmologist and topical medication was prescribed by GPs in 32% of contacts. The estimated annual cost of GP visits, specialist visits and topical medication was AUD$3.2 m. There were 6997 claims for pterygium removal in 1999/2000 with 3192 conjunctival autografts. Rates of pterygium removal were highest in Queensland with 56 per 100,000 population. The annual costs of surgical intervention were estimated at AUD$4.8 m.

CONCLUSIONS

The direct medical costs of pterygium in Australia are AUD$8.3 m annually. This is likely to be an underestimate of total cost because indirect costs such as loss of work time could not be measured. More data are needed on the long-term benefits of pterygium intervention.

Nutrient management programs, nitrogen fertilizer practices, and groundwater quality in Nebraska's Central Platte Valley (U.S.), 1989-1998

Given the societal concern about groundwater pollution from agricultural sources, public programs have been proposed or implemented to change farmer behavior with respect to nutrient use and management. However, few of these programs designed to change farmer behavior have been evaluated due to the lack of detailed data over an appropriate time frame. The Central Platte Natural Resources District (CPNRD) in Nebraska has identified an intensively cultivated, irrigated area with average groundwater nitrate-nitrogen (N) levels about double the EPA"s safe drinking water standard. The CPNRD implemented a joint education and regulatory N management program in the mid-1980s to reduce groundwater N. This analysis reports N use and management, yield, and groundwater nitrate trends in the CPNRD for nearly 3000 continuous-corn fields from 1989 to 1998, where producers faced limits on the timing of N fertilizer application but no limits on amounts. Groundwater nitrate levels showed modest improvement over the 10 years of this analysis, falling from the 1989-1993 average of 18.9 to 18.1 mg/l during 1994-1998. The availability of N in excess of crop needs was clearly documented by the CPNRD data and was related to optimistic yield goals, irrigation water use above expected levels, and lack of adherence to commercial fertilizer application guidelines. Over the 10-year period of this analysis, producers reported harvesting an annual average of 9729 kg/ha, 1569 kg/ha (14%) below the average yield goal. During 1989-1998, producers reported annually applying an average of 162.5 kg/ha of commercial N fertilizer, 15.7 kg/ha (10%) above the guideline level. Including the N contribution from irrigation water, the potential N contribution to the environment (total N available less estimated crop use) was estimated at 71.7 kg/ha. This is an estimate of the nitrates available for denitrification, volatilization, runoff, future soil N, and leaching to groundwater. On average, between 1989-1993 and 1994-1998, producers more closely followed CPNRD N fertilizer recommendations and increased their use of postemerge N applications--an indication of improved synchrony between N availability and crop uptake.