Chemical and biological evaluation of Egyptian Nile Tilapia (Oreochromis niloticas) fish scale collagen.

Collagen is considered to be one of the most useful biomaterials with different medical applications. However, collagen properties differ from one source to another. The aim of this study was to extract, purify, characterize and perform preliminary biological evaluation of type I collagen from scales of Egyptian Nile Tilapia. Pepsin-solubilized collagen (PSC) was successfully prepared from Nile Tilapia fish scale waste. Lyophilized collagen was dissolved in dilute HCl to form acidic collagen solutions (ACS) which was neutralized to form gel. To confirm the biocompatibility of the produced gel, baby hamster kidney (BHK-21) fibroblast cells were seeded onto a 3D collagen gel (0.3% and 0.5%, w/v). The results of an SDS-PAGE test showed that the extracted collagens were type I collagen, with α chain composition of (α1)2α2. Thermal analysis showed that the denaturation temperature was 32 °C. X-ray diffraction (XRD) analysis and Fourier-transform infrared spectra (FTIR) showed that the extracted collagen had a triple helix structure. Active proliferation of BHK-21 cells with no signs of toxicity was evident with both collagen gel concentrations tested. The results show that Nile Tilapia scales can be an effective source of collagen extraction that could be used as a potential biomaterial in biomedical applications.

Hepatitis B prevalence in Denmark - an estimate based on nationwide registers and a national screening programme, as on 31 December 2007.

The prevalence of chronic hepatitis B virus (HBV) infection in Denmark is not clear. The primary aim of this study was to estimate the prevalence of chronic HBV infection in Denmark. The capture­recapture method was used to estimate the total population diagnosed with chronic HBV infection in Denmark using four nationwide registers. The population with undiagnosed chronic HBV infection was estimated by incorporating data from a two-year nationwide HBsAg screening programme in pregnant women. We identified 4,466 individuals with chronic HBV infection in the four registers until the end of 2007, and the capture­recapture estimate of the total population diagnosed with chronic hepatitis B was 7,112 (95% confidence interval (CI): 6,953­10,747). Only 17% of the identified patients attended recommended clinical care according to national guidelines. Including undiagnosed patients, the current population alive with HBV infection was 10,668 (95% CI: 10,224­16,164), corresponding to a prevalence of 0.24% (95% CI: 0.23­0.37%) in the Danish population older than 15 years. The estimated prevalence of chronic HBV infection among adults in Denmark was lower than reported from other northern European countries. Only half of the infected population had been diagnosed, and a minority attended specialised clinical care.

Lateral subvastus approach with osteotomy of the tibial tubercle for total knee replacement: a two-year prospective, randomised, blinded controlled trial.

The lateral subvastus approach combined with an osteotomy of the tibial tubercle is a recognised, but rarely used approach for total knee replacement (TKR). A total of 32 patients undergoing primary TKR was randomised into two groups, in one of which the lateral subvastus approach combined with a tibial tubercle osteotomy and in the other the medial parapatellar approach were used. The patients were assessed radiologically and clinically using measurement of the range of movement, a visual analogue patient satisfaction score, the Western Ontario McMasters University Osteoarthritis Index and the American Knee Society score. Four patients were lost to the complete follow-up at two years. At two years there were no significant differences between the groups in any of the parameters for clinical outcome. In the lateral approach group there was one complication due to displacement of the tibial tubercle osteotomy and two osteotomies took more than six months to unite. In the medial approach group, one patient had a partial tear of the quadriceps. There was a significantly greater incidence of lateral patellar subluxation in the medial approach group (3 of 12) compared with the lateral approach group (0 of 16) (p = 0.034), but without any apparent clinical detriment. We conclude that the lateral approach with tibial tubercle osteotomy is a safe technique with an outcome comparable with that of the medial parapatellar approach for TKR, but the increased surgical time and its specific complications do not support its routine use. It would seem to be more appropriate to reserve this technique for patients in whom problems with patellar tracking are anticipated.

Glossary of terms relating to capture-recapture methods.

This glossary provides basic definitions for terms that have a specific meaning in the application of the capture-recapture methodology, particularly with respect to standard techniques for the application of log linear models to multiple lists. In epidemiology, capture-recapture is used for prevalence estimation. It is intended that, as well as being a central point of reference for terms used in the capture-recapture methodology, this glossary should provide a resource for those new to this methodology. It aims to provide a simple introduction using terms that should be understood by an uninitiated audience.

Validation of a semi-quantitative food-frequency questionnaire used among 2-year-old Norwegian children.

OBJECTIVES: An adequate diet is of profound importance in infancy and early childhood. To ensure an optimal diet, knowledge about actual intake must be obtained. The aims of this study were to assess the validity of a semi-quantitative food-frequency questionnaire (SFFQ) applied in a large nation-wide survey among 2-year-old children and to examine the validity of the SFFQ in relation to different background parameters. DESIGN: The SFFQ was administered to the parents close to the child's second birthday, and one to two weeks later they started to weigh and record the child's diet for 7 days. SUBJECTS: One-hundred and eighty-seven families with a 2-year-old child completed both methods. RESULTS: There were no differences between the intakes of protein, saturated fatty acids, total carbohydrates and calcium estimated from the two methods. The average intake of all micronutrients, except for calcium, was overestimated by the SFFQ. Bland-Altman plots showed a systematic increase in difference between the two methods with increasing intake for most nutrients. Spearman correlation coefficients between methods for nutrient intakes ranged from 0.26 to 0.50, the median correlation was 0.38. The correlations increased when estimates were adjusted for energy intake, the median correlation being 0.52. Differences in observed validity were found according to the number of siblings. CONCLUSIONS: This study indicates that the SFFQ may be a valuable tool for measuring average intakes of energy, macronutrients and several food items among a 2-year-old population in Norway. The ability of the questionnaire to rank children according to intakes of nutrients and food items was rather low.

Iron status in a group of Norwegian children aged 6-24 months.

UNLABELLED: An adequate iron status is of vital importance for health and development in infancy and early childhood. Iron status was evaluated in a group of full-term Norwegian children followed longitudinally, at the ages of 6 mo (n = 278), 12 mo (n = 249) and 24 mo (n = 231) by measuring haemoglobin (Hb), mean cell volume (MCV) and serum ferritin. At 6, 12 and 24 mo of age, 3, 10 and 12%, respectively, had iron deficiency anaemia (IDA) defined as Hb <110 g/l in combination with ferritin <15 microg/l. With more restrictive criteria for defining IDA (Hb <110 g/l or <105 g/l in combination with ferritin <12 microg/l), the prevalence decreased to 1-2% at 6 mo and 2-5% at 12 and 24 mo of age. If children with a history of fever in the previous month were excluded, the proportion of children with depleted iron stores (ferritin <10 microg/l) increased from 2 to 3% at 6 mo, from 5 to 7% at 12 mo and from 9 to 13% at 24 mo. CONCLUSION: Mild iron deficiency anaemia exists among otherwise healthy Norwegian infants and toddlers. The prevention and early treatment of iron deficiency should be a priority for the child health services.

Inoculum type does not affect overall resistance of an arbuscular mycorrhiza-defective tomato mutant to colonisation but inoculation does change competitive interactions with wild-type tomato.

• The influence of inoculum type on colonisation of a mycorrhiza-defective tomato mutant, rmc, by the AM fungus Glomus coronatum was studied by comparing inoculum composed predominantly of spores with hyphae growing from mycorrhizal 'nurse plants', including the wild-type tomato progenitor (WT), other Lycopersicon species, and leek. • Colonisation of rmc was not primarily influenced by inoculum source; minor differences could be attributed to differences in inoculum potential. The mutation is therefore different from other mycorrhiza-defective tomato mutants. • Growth of rmc was reduced in the presence of nurse plants, because of competition with them, so a second experiment examined the effects of AM colonisation on competition between rmc and the WT tomato. This experiment was a replacement series in which rmc and WT were grown in competition and as single plants, inoculated with G. coronatum or uninoculated. • The WT did not respond to G. coronatum when grown alone, but responded positively when in competition with rmc. We conclude from the second experiment that mycorrhizal responsiveness is influenced by competition with (in this case) a surrogate nonhost plant rmc in a situation that mimics interspecific competition. It is therefore a community-based parameter. Results are discussed in the context of responses of mycorrhizal vs nonmycorrhizal species and competition in natural plant ecosytems.

Monitoring hepatitis C virus infection among injecting drug users in the European Union: a review of the literature.

Hepatitis C virus (HCV) among injecting drug users (IDUs) is one of the European Union's (EU) major public health problems. This review examines the current state of knowledge regarding HCV among IDUs in EU countries. Studies published between January 1990 and December 2000, were identified through a computerized search (MEDLINE and EMBASE). Ninety-eight studies have reported prevalence for HCV among groups of IDUs in all EU countries except Luxembourg. The prevalence of anti-HCV ranged from 30 to 98%. Incidence rates ranged from 6.2 to 39.3 per 100 person years. This review provides a comprehensive examination of HCV infection among IDUs in the countries of the EU, and quite clearly demonstrates that the quality and epidemiological relevance of the studies published varies widely. Thus, the reported data may not reflect accurately the current or recent past prevalence of HCV among IDUs in the EU. A strategic approach to the surveillance of HCV among IDUs in the EU, utilizing robust and consistent methods, is required urgently.

The attendance pattern of clients at a Scottish needle exchange.

AIMS: To examine the pattern of attendance at a Scottish needle exchange. DESIGN: Semi-structured interviews and retrospective analysis of attendance patterns. SETTING: A needle exchange in a Scottish city which covers the whole of the city. PARTICIPANTS: Clients and staff of the needle exchange. MEASUREMENTS: The attendance pattern of 1556 clients of the needle exchange over a 4-year period 1995-1998. FINDINGS: The average frequency of attendance over the 4-year period was 12.7. In 1998, 23% had only visited the needle exchange once and 11% had only visited twice. CONCLUSIONS: A significant minority of clients only attend the needle exchange once or twice a year. There is a need to include information on client retention in future evaluations of needle and syringe exchange clinics and to specify the kind of relationships needle and syringe exchange clinic staff are expected to develop with clients and what level of client retention they should be aiming towards in a well-run clinic.

Capture-recapture estimates of drug misuse in urban and non-urban settings in the north east of Scotland.

AIMS: To estimate the prevalence of opiate or benzodiazepine misuse in the Grampian Health Board area, Scotland and illustrate the use of the capture-recapture method in both rural and urban settings. DESIGN: Capture-recapture analyses on six distinct sources of data with unequal coverage of the geographical area. SETTING: Grampian Health Board area, including the City of Aberdeen. PARTICIPANTS: Data were collated from the Police, Social Work Departments, GPs contributing to the Scottish Drug Misuse Database, statutory drug agencies, a voluntary sector drug agency and a needle/syringe exchange. MEASUREMENTS: In total 1770 individuals were identified as misusing opiates or benzodiazepines and residing in the Grampian Health Board area; 1129 individuals were resident in the City of Aberdeen. FINDINGS: The total number of opiate or benzodiazepine misusers in the City of Aberdeen was estimated to be 2519 (95% CI 2048-3200). This figure corresponds to 2.0% (1.6-2.5%) of the population aged 15-54 years. In a town to the north of Aberdeenshire where high levels of heroin use had previously been reported in the media, 2.5% of the population aged 15-54 (1.8-3.8%) were estimated to be misusing opiates or benzodiazepines. CONCLUSIONS: Although there may be difficulties in applying capture-recapture methods in all settings, the methodology can give valuable information on the extent of drug misuse in both urban and non-urban areas. This information is particularly important to assess the spread of drug misuse from cities to rural areas.

Mathematical modelling of the spread of HIV/AIDS amongst injecting drug users.

In this paper we develop and analyse a model for the spread of HIV/AIDS amongst a population of injecting drug users. Our work is based on a model originally due to Kaplan (1989, Rev. Inf. Diseases 11, 289-98). We start off with a brief literature survey and review; this is followed up by a detailed description of Kaplan's model. We then outline a more realistic extension of Kaplan's model. Then we perform an equilibrium and stability analysis on this model. We find that there is a critical threshold parameter Rzero which determines the behaviour of the model. If Rzero < or = 1 there is a unique disease-free equilibrium, and if Rzero < 1 the disease dies out. If Rzero > 1 this disease-free equilibrium is unstable, and in addition there is a unique endemic equilibrium which is locally stable. If a certain condition is satisfied (and for Kaplan's model this condition is always satisfied), additional complete global-stability results are shown. These results are confirmed and explored further by simulation.

Parotid lipomatosis.

A case of parotid lipomatosis is reported, and the literature is reviewed. This rare condition presents as a slow growing parotid mass, which may be diagnosed preoperatively using computed tomography or magnetic resonance imaging. Long-term clinical follow-up is important because apparently complete surgical excision may be complicated by recurrence.

Contrasting methods of collecting data on injectors' risk behaviour.

In this paper two contrasting methods of collecting data on drug injectors' needle and syringe sharing practices are considered, namely: direct questions about any previous sharing in the last 6 months, and vignettes in which injectors are asked to indicate whether they would be prepared to share injecting equipment in a range of situations. Injectors' statements of their preparedness to share are far in excess of their reports of actual sharing. The possible reasons for this discrepancy are considered, including that injectors may have under-reported the level of their actual sharing. It is suggested that in future studies aiming to collect risk behaviour data should seek to combine methods rather than to rely solely upon direct questioning of any past sharing.

Estimating the prevalence of drug misuse in Dundee, Scotland: an application of capture-recapture methods.

STUDY OBJECTIVES: To apply capture-recapture methods to provide an estimate of the prevalence of opiate and benzodiazepine misuse in Dundee, Scotland. DESIGN: A four sample capture-recapture method using data from both statutory and non-statutory data sources to estimate drug misuse prevalence in Dundee between January 1990 and December 1994. PARTICIPANTS: Users of benzodiazepines or opiates residing within Dundee. RESULTS: Altogether 855 drug misusers were identified from various sources within Dundee; many were identified from more than one source. Using this data, the estimated unknown population was 1702, giving a total population of 2557 (95% confidence interval (CI) 1974, 3458) who misuse benzodiazepines or opiates. This represents a prevalence of 28.8 (95% CI 22.3, 39.0) per thousand. CONCLUSIONS: Capture-recapture techniques can be applied to statutory and non-statutory agency data to produce an estimate of at least certain sections of the drug misusing population. However, it is important to recognise the limitations of this methodology and in future to seek to combine a range of approaches to the problem of estimating prevalence rather than sticking rigidly to any single approach.