Light-emitting diodes (LED) for domestic lighting: any risks for the eye?

Light-emitting diodes (LEDs) are taking an increasing place in the market of domestic lighting because they produce light with low energy consumption. In the EU, by 2016, no traditional incandescent light sources will be available and LEDs may become the major domestic light sources. Due to specific spectral and energetic characteristics of white LEDs as compared to other domestic light sources, some concerns have been raised regarding their safety for human health and particularly potential harmful risks for the eye. To conduct a health risk assessment on systems using LEDs, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES), a public body reporting to the French Ministers for ecology, for health and for employment, has organized a task group. This group consisted physicists, lighting and metrology specialists, retinal biologist and ophthalmologist who have worked together for a year. Part of this work has comprised the evaluation of group risks of different white LEDs commercialized on the French market, according to the standards and found that some of these lights belonged to the group risk 1 or 2. This paper gives a comprehensive analysis of the potential risks of white LEDs, taking into account pre-clinical knowledge as well as epidemiologic studies and reports the French Agency's recommendations to avoid potential retinal hazards.

[Primary and acquired resistance to antituberculous drugs in strains of Mycobacterium tuberculosis isolated in Rwanda]. / Résistance primaire et acquise aux antituberculeux des souches de Mycobacterium tuberculosis isolées au Rwanda.

This study was undertaken within the framework of a surveillance project on the resistance of Mycobacterium tuberculosis to first-line antituberculosis drugs in four provinces of Rwanda with a high prevalence of tuberculosis (TB). The purpose was to determine the prevalence of primary and acquired resistance of M. tuberculosis to major antituberculosis drugs. A cohort of patients (n=710) with pulmonary TB documented by positive microscopic examinations of exhaustive samples was recruited at 7 treatment centers. Sputum samples were cultured on Löwenstein-Jensen and Coletsos media. Sensitivity to antituberculosis drugs was tested using a BACTEC 460 radiometric system. M. tuberculosis was isolated in 644 of the 710 patients (90.7%). A total of 296 out of 573 tested for HIV infection (51.7%) were positive. Primary resistance to one, two, three or four antituberculosis drugs was observed in 3.5%, 2.9%, 1.4% and 5.7% respectively. The prevalence of acquired resistance to antituberculosis drugs was 11.2%. Primary monoresistance to streptomycin was the most prevalent (2.3%) followed by resistance to ethambutol (1%). The combined rate of multiresistance was 11.6% with 7% involving new cases and 25.5% involving retreatment. This study showed that the rates of primary and acquired resistance to first-line antituberculosis drugs were high and that TB was associated with HIV infection. The National TB Control Program must implement measures to coordinate diagnosis and management of TB and HIV infection.

Resistance primaire et acquise aux antituberculeux des souches de Mycobacterium tuberculosis isolees au Rwanda

Le cadre de l'etude de la resistance de Mycobacterium tuberculosis aux antituberculeux de premiere ligne se situe dans quatre provinces du Rwanda a forte prevalence de tuberculose (TB). L'objectif etait de determiner les prevalences de resistance primaire et acquise de M. tuberculosis aux antituberculeux majeurs. Une cohorte de patients avec TB pulmonaire a microscopie positive (n=710) echantillonnes de maniere exhaustive a ete incluse entre septembre 2002 et mars 2004 dans 7 centres de traitement. Leurs expectorations ont ete ensemencees sur milieux de Lowenstein-Jensen et Coletsos. La sensibilite aux antituberculeux a ete testee par lamethode radiometrique BACTEC 460. Sur 710malades;M. tuberculosis a ete isole chez 644 (90;7). Parmi eux; 296/573 (51;7) etaient positifs pour leVIH. La resistance primaire a un; deux; trois ou quatre antituberculeux etait de 3;5; 2;9; 1;4et 5;7respectivement. La resistance acquise a un antituberculeux etait de 11;2. La monoresistance primaire a la streptomycine etait la plus frequente (2;3); suivie de la resistance a l'ethambutol (1). Le taux combine de multiresistance representait 11;6; avec 7chez les nouveaux cas et 25;5chez les re-traites. Les taux de resistance primaire et acquise aux antituberculeux de premiere ligne sont eleves et la TB est associee au VIH. Le Programme National de lutte contre la TB devrait mettre en place une bonne coordination dans le diagnostic et la prise en charge de la TB et de l'infection par le VIH

Evaluation of the resazurin microtiter assay for rapid detection of ofloxacin resistance in M. tuberculosis.

OBJECTIVE: To evaluate the performance of the colorimetric resazurin microtiter assay (REMA) method for the detection of ofloxacin resistance. METHODS: A panel of 120 multidrug-resistant Mycobacterium tuberculosis strains was tested blindly by the REMA method and compared with the results obtained using the BACTEC 460 method. RESULT: A very good correlation was observed between the two methods. CONCLUSION: The REMA method is simple, rapid and can be an inexpensive alternative procedure for the rapid detection of anti-tuberculosis drug resistance in laboratories with limited resources.

Arcobacter species in humans.

During an 8-year study period, Arcobacter butzleri was the fourth most common Campylobacter-like organism isolated from 67,599 stool specimens. Our observations suggest that A. butzleri displays microbiologic and clinical features similar to those of Campylobacter jejuni; however, A. butzleri is more frequently associated with a persistent, watery diarrhea.

Critical use of nucleic acid amplification techniques to test for Mycobacterium tuberculosis in respiratory tract samples.

The usefulness of employing Belgian selection criteria before performing nucleic acid amplification techniques (NAT) was evaluated. The results of this study show that for smear-negative patients with an abnormal chest radiology result in the absence of a respiratory tract infection by bacterial pathogens, testing with NAT is of major benefit.

Prevalence of genotypic resistance among antiretroviral drug-naive HIV-1-infected patients in Belgium.

OBJECTIVES: To estimate the prevalence and the evolution over time (1995-1998) of genotypic resistance to antiviral drugs in antiretroviral drug-naive HIV-1-infected patients in Belgium. DESIGN: Belgian Aids Reference Laboratories provided retrospective samples and clinical data from antiretroviral drug-naive HIV-1-infected patients who visited the hospital for the first time in 1995 (n=45), 1997 (n=75) and 1998 (n=111). Genotypic resistance to the three available classes of drugs was monitored using the Line Probe Assay (Innogenetics, Gent, Belgium). Additionally, ARMS-151 was performed for scoring multinucleoside resistance. RESULTS: The prevalence of genotypic resistance at baseline to nucleoside analogue reverse transcriptase inhibitors (NRTIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs) were each between 10% and 20% for 1995, 1997 and 1998 without an increasing trend over time. For NRTIs, resistance mutations were mainly related to zidovudine in 1995, whereas in 1997 and 1998 baseline resistance was scored for zidovudine, lamivudine or for both drugs simultaneously. No patients displayed the multi-nucleoside resistance Q151M mutation. Baseline resistance mutations to protease inhibitors (PIs) did not rise significantly: 4.4% in 1995, 8% in 1997 and 9.9% in 1998. When scoring any resistance-related mutation, 26.6% displayed genotypic baseline resistance in 1995, 26.6% in 1997 and 31.5% in 1998. DISCUSSION: The prevalence of genotypic baseline resistance to any drug, as scored with LiPA, in naive HIV-1 patients in Belgium is 29%, with baseline resistance mutations to one or several drugs from all available classes of antiviral drugs. The ability of LiPA to pick up minor variants could be an explanation for the higher overall prevalence we observe, when compared to recent estimates in other countries of 16.3% and 22%, which were based on sequencing methods. According to the European guidelines for resistance testing, resistance testing in Belgium before starting antiviral therapy should be considered.

Longitudinal comparison of virus load parameters and CD8 T-cell suppressive capacity in two SIVcpz-infected chimpanzees.

In a longitudinal study we address the hypothesis that resis tance to disease progression in lentivirus-infected chimpanzees is related to potent non-cytotoxic suppression of virus replication. In a long-term follow-up, the viral suppressive capacity in two simian immunodeficiency virus (SIV)cpz-infected chimpanzees was correlated with two polymerase chain reaction (PCR)- and two culture-based virus load measurements. In both animals, quantitative virus isolation (QVI) tended to decline slowly, whereas in vitro virus suppression was sustained or increased over time. In general, plasma virus loads in SIVcpz-infected animals were maintained for extended periods of time. Based on current assays that measure virus suppressive capacity in peripheral blood, it was not possible to conclude that virus suppression played a major role in the maintenance of the disease-free state in lentivirus-infected chimpanzees.

Effectiveness of antiretroviral therapy initiated before the age of 2 months in infants vertically infected with human immunodeficiency virus type 1.

UNLABELLED: The effectiveness and tolerance of antiretroviral therapy with a combination of three reverse transcriptase inhibitors starting at the time of diagnosis (before 2 months of age) was evaluated in four infants with vertically acquired HIV-1 infection. Plasma HIV-1 RNA levels ranged from 230,000 to 1,000,000 copies/ml before onset of triple therapy and fell below 50 copies/ml at 12 to 33 weeks of life in three of the infants. These three children, currently aged 158, 105 and 72 weeks, are asymptomatic, have normal lymphocyte subsets and no hypergammaglobulinaemia. Two children experienced a profound reduction in the amount of proviral DNA detected in blood and have become HIV-1 seronegative, although one of them has had HIV-1 RNA detectable on a single occasion at 114 weeks of life (303 copies/ml). Transient interruption of therapy resulted in a rapid but reversible increase in HIV-1 RNA levels in the third child and was associated with the production of HIV-specific antibodies. The fourth child whose parents were not compliant to treatment and follow-up had a poor virological response. CONCLUSION: Early treatment of vertically acquired human immunodeficiency virus type 1 infection with three reverse transcriptase inhibitors is well tolerated and can result in such suppression of viral replication that specific antibodies are not produced, that proviral DNA falls to the lower limit of quantitation in blood and that all clinical and immunological manifestations of infection are avoided. Parental adhesion is crucial to the effectiveness of therapy.

Blinded, multicenter quality control study for the quantification of human immunodeficiency virus type 1 RNA in plasma by the Belgian AIDS reference laboratories.

OBJECTIVE: In order to evaluate the interlaboratory variation of HIV-1 RNA measurements in plasma, the Belgian AIDS reference laboratories organized a blinded multicenter quality control study. METHODS: Atest panel of coded spiked HIV-1 plasma samples reflecting the dynamic range of the assay was composed and distributed. The HIV-1 RNA concentration of these samples was determined by the eight Belgian AIDS reference laboratories by means of the Amplicor HIV-1 Monitor version 1.5 assay. RESULTS: Analysis of the results demonstrated that there was little interlaboratory variation for the high concentration range (4.0-5.7 log10 copies/mL), never exceeding 0.2 log10 copies/mL. However the standard deviation for the low concentration range (2.6-3.9 log10 copies/mL) reached up to 0.22 log10 copies/mL. CONCLUSIONS: Since interlaboratory variability never reached 0.5 log10 copies/mL and each of the laboratories was able to detect four-fold differences in plasma HIV-1 RNA levels, the Amplicor assay can be used in multicenter studies without a centralized analysis of samples. Furthermore, this well-characterized proficiency panel of spiked plasma samples could be used as a standard in the study of interassay comparisons.

Isolation of HIV-1 RNA from plasma: evaluation of eight different extraction methods.

The efficacy of eight different methods for the extraction of HIV-1 RNA from plasma was compared. The RNA preparation method that gave the best results by RT-PCR was the one described by Chomczynski and Sacchi (1987, Anal. Biochem. 162, 156-159). This method consists of a guanidine thiocyanate treatment followed by three phenol-chloroform-isoamylalcohol extractions and an ethanol precipitation. The disadvantage of this method is that it is time consuming and less suitable for the extraction of large series of samples. Moreover, due to the large number of procedural steps, there is a greater risk of sample mix-up or contamination. Of the single-step RNA purification methods, good results were obtained with the TRIzol method (Gibco Life Technologies, Paisley, UK) and with the extraction method offered by the NASBA kit (Organon Teknika, Turnhout, Belgium). The above single-step methods are recommended since both are sensitive enough to detect low copy numbers of HIV-RNA in the plasma of asymptomatic patients, and require only 2 h for completion. For most of the methods evaluated the inter-test variability was acceptable (mean variation coefficient between duplicate extraction varied between 17.3 and 47.3%). Inter-laboratory reproducibility was evaluated only for the TRIzol-method and found to be low (mean variation coefficient 63.4).

Comparative evaluation of NASBA HIV-1 RNA QT, AMPLICOR-HIV monitor, and QUANTIPLEX HIV RNA assay, three methods for quantification of human immunodeficiency virus type 1 RNA in plasma.

Three commercial assays for quantifying plasma human immunodeficiency virus type 1 (HIV-1) RNA were evaluated. The assays differed in their sample volumes, the means of preparing samples, and methods of amplification and detection. Plasma samples were obtained from 36 HIV-1-infected patients representing all stages of HIV-1 infection and were analyzed as coded specimens. Measurement of HIV-1 RNA baseline levels revealed no significant difference in sensitivity between the three assays. The assays were also applied to the quantitation of HIV-1 RNA levels in the plasma of patients who were changing their antiretroviral therapy. The changes measured in HIV-1 RNA levels in plasma in response to therapy were comparable by the three assays. No close correlation was found between the amount of HIV-1 RNA and the CD4 T-cell count; HIV-1 RNA assays were more sensitive than p24 antigen assays as an indicator of plasma viremia. Overall, the study demonstrates that all three quantitative assays for HIV-1 RNA can be used to measure the HIV-1 RNA copy number representing the HIV-1 viremia status in patients with HIV-1 infection. Since this copy number is likely to be useful in monitoring the effectiveness of antiviral therapy, these quantitative assays for HIV-1 RNA are ready to be built into clinical trials.

Quantitation of HIV-1 in whole blood of infected children.

OBJECTIVE: To validate the technique of HIV-1 culture from whole blood for the quantitation of viral load in infected children. PATIENTS: Forty-three HIV-1-infected children were followed in two paediatric centres. METHODS: Quantitative HIV-1 cultures from unfractionated whole blood using an end-point dilution technique were compared with simultaneous quantitative cultures of peripheral blood mononuclear cells (PBMC) and plasma. RESULTS: Good sensitivity (93%) of the methods used was confirmed. A close correlation (r = 0.80) was observed between HIV-1 titres measured directly from whole blood and those expected from PBMC and plasma titres. The mean whole blood viral load was higher in patients with more severe signs of disease, but the difference did not reach statistical significance. The whole blood viral titres measured sequentially at monthly intervals remained within one dilution of each other in 16 of the 22 patients studied. CONCLUSION: In this study, the quantitation of HIV-1 in unfractionated blood allowed for a reliable and sensitive measurement of the whole blood viral load in infected children.

Risk factors for HIV seropositivity in selected urban-based Rwandese adults.

In January 1987, HIV antibodies were detected by means of an immunoenzymatic assay, indirect immunofluorescence and Western blot in 52 out of 302 male urban-based professionals and in 28 out of 150 health workers in Kigali, Rwanda. Univariate analysis showed an association between HIV seropositivity and a history of sexually transmitted diseases (STD), blood transfusion, medical injections for treatment of STD, and medical injections for treatment of febrile illnesses. However, injection related to treatment of other conditions were not associated with HIV seropositivity. Among health workers, no association between HIV seropositivity and professional or accidental exposure to HIV-infected patients or to their body fluids was identified. Discriminant analysis showed that HIV seropositivity was associated only with a history of STD and with a history of blood transfusion. In central Africa, a history of STD and a history of blood transfusion should be considered as risk factors for HIV seropositivity. Medical or accidental injections do not seem to play a major role in the transmission of HIV among adults in central Africa.

HIV antibodies in a remote rural area in Rwanda, Central Africa: an analysis of potential risk factors for HIV seropositivity.

Detection of HIV antibodies by means of an immunoenzymatic assay, an indirect immunofluorescence technique and Western blot was attempted on 375 serum samples collected in the Murunda area, a remote rural area situated in Rwanda, central Africa. Two out of 147 (1.4%) adults from a strict rural area, five out of 59 (8.5%) adults from an adjacent market place, and 49 out of 169 (30%) STD clinic attenders from the same area were HIV seropositive. In the first two groups, HIV seropositivity was associated with a history of sexually transmitted disease (STD) in the previous 2 years (P less than 0.001) and with a history of travel to a Rwandese urban centre in the previous 5 years (P less than 0.05). This study suggests that HIV seroprevalence is low in rural central Africa compared with urban centres. Risk factors for HIV seropositivity are similar in rural and urban-based adults in Rwanda, i.e. heterosexual promiscuity and STDs. Many HIV seropositive rural subjects from this study are likely to have acquired HIV infection through sexual contacts in Rwandese cities.

PIP: 375 serum samples collected from youth and adults in Murunda, a remote rural area in Rwanda, were analyzed for antibodies to human immunodeficiency virus (HIV). Study subjects were drawn from 3 selected populations: those from the village of Rulimba, a strictly rural area; adults from Gisiza, an adjacent rural market place that is connected by roads to 2 other cities; and patients from the same district who attended the Murunda health center for treatment of a sexually transmitted disease during the study period. The prevalence of HIV seropositivity was 2/147 (1.4%) in the strictly rural group, 5/59 (8.5%) in the market place area, and 49/169 (30%) among patients receiving treatment for sexually transmitted diseases. No significant differences existed between male and female subjects in terms of HIV seropositivity. HIV seropositivity was also associated with a history of venereal diseases in the market place sample. These results suggest that Rwanda's rural population (93%) is at lower risk of HIV infection that the urban population. Where HIV infection does exist in rural areas, it is transmitted mainly by heterosexual contact with persons from urban centers. The relatively high rate of HIV infection observed in adults living in a rural market place accessible from most of the Rwandan main cities, together with the association between HIV seropositivity and past residency or travel in urban centers, indicates that most of the rural-based seropositive adults identified in this study were infected elsewhere. These findings also contradict the popular assumption that HIV was present in an unrecognized form for many years in rural Central Africa.