Tuberculosis contact investigation in African Portuguese-speaking countries at End TB Strategy era: a scoping review

OBJECTIVES

The contact investigation of tuberculosis (TB) index case is one of the critical elements pointed by the WHO to reach the end of the TB epidemic. The scoping review aimed to map out the recommended and the adopted processes applied to active contact investigation of TB index case in African Portuguese-speaking countries (PALOP).

DESIGN

Scoping review.

DATA SOURCES

We searched B-on, Cochrane Library, PubMed, Web of Science, Scopus, WHOLIS, IRIS, OKR, each country's Ministry of Health websites, WHO, Global Fund, World Bank and bibliographic reference lists from February to May 2020.

ELIGIBILITY CRITERIA

All available literature on TB contact investigation in each country part of PALOP (Angola, Cape Verde, Guinea-Bissau, Mozambique and Sao Tome and Principe) published from 1 January 2010 to 31 January2020.

DATA EXTRACTION AND SYNTHESIS

A data-charting form was developed to extract data on documents' characteristics and variables pertinent to the TB contact investigation process. Before qualitative analysis, we thematically synthesised findings and converted them into appropriate text units.

RESULTS

Fifteen documents were included in the scoping review. The recommended processes for TB contact investigation were identified only for Cape Verde and Mozambique. It included clinical evaluation, counselling and testing for HIV, chest radiography, tuberculin skin test, sputum smear microscopy or Xpert MTB/RIF. The adopted processes were detected only in research studies from Angola, Guinea-Bissau and Mozambique. Therefore, they cannot be assumed as adopted within the scope of the national programmes of the respective countries.

CONCLUSION

This review highlights the scarcity of references on TB contact investigation in PALOP at the End TB Strategy era. Furthermore, it is well clear the importance of an information system that provides actual data for assessing the real impact of such interventions in controlling the disease in African Portuguese-speaking countries.

The circuits of healthcare: Understanding healthcare seeking behaviour-A qualitative study with tuberculosis patients in Lisbon, Portugal

BACKGROUND

Understanding health delivery service from a patient´s perspective, including factors influencing healthcare seeking behaviour, is crucial when treating diseases, particularly infectious ones, like tuberculosis. This study aims to trace and contextualise the trajectories patients pursued towards diagnosis and treatment, while discussing key factors associated with treatment delays. Tuberculosis patients' pathways may serve as indicator of the difficulties the more vulnerable sections of society experience in obtaining adequate care.

METHODS

We conducted 27 semi-structured interviews with tuberculosis patients attending a treatment centre in a suburban area of Lisbon. We invited nationals and migrant patients in active treatment to participate by sharing their illness experiences since the onset of symptoms until the present. The Health Belief Model was used as a reference framework to consolidate the qualitative findings.

RESULTS

By inductive analysis of all interviews, we categorised participants' healthcare seeking behaviour into 4 main types, related to the time participants took to actively search for healthcare (patient delay) and time the health system spent to diagnose and initiate treatment (health system delay). Each type of healthcare seeking behaviour identified (inhibited, timely, prolonged, and absent) expressed a mindset influencing the way participants sought healthcare. The emergency room was the main entry point where diagnostic care cascade was initiated. Primary Health Care was underused by participants.

CONCLUSIONS

The findings support that healthcare seeking behaviour is not homogeneous and influences diagnostic delays. If diagnostic delays are to be reduced, the identification of behavioural patterns should be considered when designing measures to improve health services' delivery. Healthcare professionals should be sensitised and perform continuous capacity development training to deal with patients´ needs. Inhibited and prolonged healthcare seeking behaviour contributes significantly to diagnostic delays. These behaviours should be detected and reverted. Timely responses, from patients and the healthcare system, should be promoted.

Manganese Migration in Li1-xMn2O4 Cathode Materials

LiMn₂O₄ has been considered one of the most promising cathode materials for Li-ion batteries due to its thermal stability, abundance, environmental affinity, and the possibility to exchange Li-ions in three-dimensions. However, it still suffers from major problems, such as capacity fading and voltage decay, which has been associated to phase transformations and dissolution of transition metals. In this report, we use scanning transmission electron microscopy, coupled with differential phase contrast (DPC), to better understand the mechanisms behind the structural transformations occurring in LiMn₂O₄. We use the fact that DPC has the ability to observe simultaneously light and heavy elements, as well as measure projected electric fields and charge distribution at the atomic level. This approach allows us to monitor the migration of very low amounts of Mn to the Li atomic positions, at the surface and subsurface regions, which otherwise is very challenging to observe using other techniques such as HAADF and ABF. These observations not only provide a fundamental understanding of the structure of LiMn₂O₄ but also reveal DPC as a novel technique to determine local structural changes in materials consisting of heavy and light elements, as well as identify the location of light elements, monitor low concentrations of substitutional species and identify phase transformations.

Adsorption of H2, O2, H2O, OH and H on monolayer MoS2

Hydrogen and hydrogen-containing gases are commonly used as reductants in chemical vapor deposition growth of MoS₂. Here, we consider the defects resulting from the presence of hydrogen during growth and the resulting electronically active defects. In particular, we find that the interstitial hydrogen defect is a negative-U center with amphoteric donor and acceptor properties. Additionally, we consider the effects of interaction with water and oxygen. The defects are analysed using density functional theory calculations.

Knowledge, attitudes and practices regarding tuberculosis care among health workers in Southern Mozambique

Background

Tuberculosis (TB) control is more likely to be achieved if the level of knowledge regarding TB is increased among health workers managing high-risk groups. No formal assessments regarding knowledge, attitudes and practises of health workers about TB have been published for Mozambique, a country facing challenges in the fight against TB, with a fragile health system and considerable work overload of health personnel. The main objective of the study was to determine the level of knowledge, identify attitudes and assess practices regarding TB care and control among health care workers of the district of Manhiça.

Methods

A descriptive cross-sectional study was performed through the use of a specifically designed Knowledge, Attitudes and Practices (KAP) questionnaire in the district of Manhiça, a high tuberculosis and HIV burden rural area in Southern Mozambique. In this district, 14 health care facilities service a population of approximately 160,000 people. The questionnaire took 30–45 min to administer with external assistance not permitted. The survey contained 79 questions pertaining to four different areas: demographics, TB knowledge, attitudes and practices.

Results

The study sample included 170 health care workers. The average knowledge score was 14.89 points (SD = 3.61) out of a total possible 26 points. Less than 30% of respondents had heard of Xpert MTB/RIF®. Seventy per cent agreed there was stigma associated with TB and 48.2% believed this stigma was greater than that associated with HIV. The average practice score was 3.2 out of 9 points (35.6%, SD = 2.4).

Conclusion

Health care worker’s knowledge gaps identified in this study may result in substandard patient care. Specific deficiencies in understanding existed in terms of paediatric TB and Xpert MTB/RIF® testing. The present study provides impetus for tailored TB education among health care workers from a high TB burden rural area in Southern Mozambique.

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-016-0344-8) contains supplementary material, which is available to authorized users.

Genetic variability affecting Exserohilum turcicum resistance in popcorn lines grown under high and low phosphorus conditions

Northern leaf blight (NLB), caused by Exserohilum turcicum, is one of the main foliar diseases that affect popcorn culture. Farmers use many control measures to minimize damage caused by this disease, among which, the use of cultivars with genetic resistance is the most effective and economical. The aim of this study was to investigate genetic variability influencing resistance to NLB in 25 popcorn maize lines grown under high and low phosphorus conditions in relation to foliar fungal disease caused by E. turcicum. We evaluated the disease incidence and severity, by analysis of variance and cluster test (Scott-Knott). There was sufficient genetic variability between strains for resistance traits. Genotypic variance was higher than environmental variance, and had more discriminatory power. We conclude that new progenies could be selected for the establishment of future populations. P-7, P-9, L-59, L-71, and L-76 progenies possess promising characteristics that simultaneously reduce the severity and the incidence of NLB in popcorn plants.

Inference of genetic diversity in popcorn S3 progenies

Molecular markers are a useful tool for identification of complementary heterotic groups in breeding programs aimed at the production of superior hybrids, particularly for crops such as popcorn in which heterotic groups are not well-defined. The objective of the present study was to analyze the genetic diversity of 47 genotypes of tropical popcorn to identify possible heterotic groups for the development of superior hybrids. Four genotypes of high genetic value were studied: hybrid IAC 125, strain P2, and varieties UENF 14 and BRS Angela. In addition, 43 endogamous S3 progenies obtained from variety UENF 14 were used. Twenty-five polymorphic SSR-EST markers were analyzed. A genetic distance matrix was obtained and the following molecular diversity parameters were estimated: number of alleles, number of effective alleles, polymorphism information content (PIC), observed and expected heterozygosities, Shannon diversity index, and coefficient of inbreeding. We found a moderate PIC and high diversity index, indicating that the studied population presents both good discriminatory ability and high informativeness for the utilized markers. The dendrogram built based on the dissimilarity matrix indicated six distinct groups. Our findings demonstrate the genetic diversity among the evaluated genotypes and provide evidence for heterotic groups in popcorn. Furthermore, the functional genetic diversity indicates that there are informative genetic markers for popcorn.

MaMP and FeMP: computational mesh phantoms applied for studying the variation of WBC efficiency using a NaI(Tl) detector

In a previous study, the counting efficiency calibration was calculated for 36 computational mesh phantoms called MaMP and FeMP-Male and Female Mesh Phantoms, which span variations in height, weight and gender. They were created to be used in a sitting configuration WBC set-up using an HPGe detector. Now this work is extended to investigate the influence of body sizes and the position of the detector on the counting efficiency (CE) for a different counting geometry. This was done by creating a new set of MaMP and FeMP mesh phantoms lying on a reclining chair and by studying the variation of the counting efficiency using a NaI(Tl) detector for the WBC set-up of SCK-CEN. The deviation of the CE due to the detector's position with respect to the phantom was investigated. Correlations were also studied for CE as a function of trunk volume, waist-hips ratio (WHR) and waist-chest ratio (WCR) for different mesh phantoms.

Genetic gains in the UENF-14 popcorn population with recurrent selection

The popcorn breeding program of Universidade Estadual do Norte Fluminense Darcy Ribeiro aims to provide farmers a cultivar with desirable agronomic traits, particularly with respect to grain yield (GY) and popping expansion (PE). We evaluated full-sib families from the seventh cycle of recurrent selection and estimated the genetic progress with respect to GY and PE. Eight traits were evaluated in 200 full-sib families that were randomized into blocks with two replicates per set in two contrasting environments, Campos dos Goytacazes and Itaocara, located in north and northwest Rio de Janeiro State, respectively. There were significant differences between sets in families with respect to all traits evaluated, which indicates genetic variability that may be explored in future cycles. Using random economic weights in the selection of superior progenies, the Mulamba and Mock index showed gains for PE and GY of 5.11 and 7.78%, respectively. Significant PE and GY increases were found when comparing the evolution of mean values of these two parameters that were assessed at cycles C₀-C₆ and predicted for C₇. Thus, an advanced-cycle popcorn cultivar with genotypic superiority for the main traits of economic interest can be made available to farmers in Rio de Janeiro State.

Origin of indirect optical transitions in few-layer MoS2, WS2, and WSe2

It has been well-established that single layer MX2 (M = Mo, W and X = S, Se) are direct gap semiconductors with band edges coinciding at the K point in contrast to their indirect gap multilayer counterparts. In few-layer MX2, there are two valleys along the Γ-K line with similar energy. There is little understanding on which of the two valleys forms the conduction band minimum (CBM) in this thickness regime. We investigate the conduction band valley structure in few-layer MX2 by examining the temperature-dependent shift of indirect exciton photoluminescence peak. Highly anisotropic thermal expansion of the lattice and the corresponding evolution of the band structure result in a distinct peak shift for indirect transitions involving the K and Λ (midpoint along Γ-K) valleys. We identify the origin of the indirect emission and concurrently determine the relative energy of these valleys.

Reactive pulsed-DC sputtered Nb-doped VO2 coatings for smart thermochromic windows with active solar control

Thermochromic VO2 thin films have successfully been grown on SiO2-coated float glass by reactive pulsed-DC magnetron sputtering. Different Nb doping amounts were introduced in the VO2 solid solution during the film growing which resulted in films with distinct semiconducting-metal phase transition temperatures. Pure VO2 showed improved thermochromic behavior as compared with VO2 films prepared by conventional DC sputtering. The transition temperatures were linearly decreased from 59 down to 34 degrees C with the increase in Nb content. However, the luminous transmittance and the infrared modulation efficiency were markedly affected. The surface morphology of the films was examined by scanning electron microscopy (SEM) and showed a tendency for grain sized reduction due to Nb addition. Moreover, the films were found to be very dense with no columnar microstructure. Structural analyses carried out by X-ray diffractometry (XRD) revealed that Nb introduces significant amount of defects in the crystal lattice which clearly degrade the optical properties.

Excitonic effects in the optical conductivity of gated graphene

We study the effect of electron-electron interactions in the optical conductivity of graphene under an applied gate and derive a generalization of Elliott's formula, commonly used for semiconductors, for the optical intensity. We show that excitonic resonances are responsible for several features of the experimentally measured midinfrared response of graphene such as the increase of the conductivity beyond the universal value above the Fermi blocked regime, the broadening of the absorption at the threshold, and the decrease of the optical conductivity at higher frequencies.

Optimizing the efficiency of the touchdown technique for detecting inter-simple sequence repeat markers in corn (Zea mays)

We evaluated the efficiency of the touchdown method to determine the ideal PCR conditions for distinct inter-simple sequence repeat primers for processing DNA from common corn, popcorn, sweet corn, and a Tripsacum-maize hybrid. Genomic DNA was extracted from eight accessions of corn: two of the dent type, one Tripsacum-maize hybrid, one sweet corn, one flint-type corn, and three popcorn. Fifteen inter-simple sequence repeat primers were used: (CT)(8)RC, (CT)(8)TG, (GA)(8)T, (GA)(8)YC, (CTC)(5)RC, (GTC)(6), (GA)(6)CC, (GT)(6)CC, (CAC)(3)GC, (AG)(8)YT, (AC)(8)T, (AC)(8)YG, (CT)(8)RG, (GGAT)(3)GA, and (GAA)(6)AA. The annealing temperature and the melting temperature for each primer were estimated using a formula for RW Genes products, or we used the temperatures indicated by the manufacturer (Invitrogen). The touchdown method was then applied to each primer, varying the number of final cycles (10 or 12) and the decrease in temperature (0.5 degrees or 1.0 degrees C intervals). The gels were compared, considering the revelation quality, band sharpness and the number of bands visualized. The touchdown-PCR method was more efficient for band amplification for most of the primers, especially at higher annealing temperatures. This type of system is useful for reducing the resources, time and effort needed for optimizing temperature conditions for a group of representative primers.

Improvement of a popcorn population using selection indexes from a fourth cycle of recurrent selection program carried out in two different environments

We estimated genetic gains for popcorn varieties using selection indexes in a fourth cycle of intrapopulation recurrent selection developed in the campus of the Universidade Estadual do Norte Fluminense. Two hundred full-sib families were obtained from the popcorn population UNB-2U of the third recurrent selection cycle. The progenies were evaluated in a randomized block design with two replications at sites in two different environments: the Colégio Estadual Agrícola Antônio Sarlo, in Campos dos Goytacazes, and the Empresa de Pesquisa Agropecuária do Estado do Rio de Janeiro (PESAGRO-RIO), in Itaocara, both in the State of Rio de Janeiro. There were significant differences between families within sets in all traits, indicating genetic variability that could be exploited in future cycles. Thirty full-sib families were selected to continue the program. The selection indexes used to predict the gains were those of Mulamba and Mock, Smith and Hazel. The best results were obtained with the Mulamba and Mock index, which allowed the prediction of negative gains for the traits number of diseased ears and ears attacked by pests, number of broken plants and lodging, as well as ears with poor husk cover. It also provided higher gains for popping expansion and grain yield than with the other indexes, giving values of 10.55 and 8.50%, respectively, based on tentatively assigned random weights.

Modelling hepatitis C virus kinetics during treatment with pegylated interferon alpha-2b: errors in the estimation of viral kinetic parameters

Neumann et al. [1] developed a widely used model for the analysis of hepatitis C virus (HCV) dynamics after the initiation of interferon therapy that assumes the effectiveness of therapy in blocking virion production, epsilon, is constant. However, with pegylated interferon alpha-2b (PEG-IFN) given weekly, there are significant changes in drug concentration between doses, leading to changes in drug effectiveness and viral rebounds. To investigate the appropriateness of the constant effectiveness (CE) model [1] for studies involving PEG-IFN, we simulated PEG-IFN treatment, using 294 sets of pharmacokinetic/pharmacodynamic (PK/PD) parameters that span observed ranges and fit the simulated data to the CE model. For most combinations of PK/PD parameters, the fits resulted in an infected cell loss rate, delta, that underestimates the true value used in the simulations and yielded over-estimates of the average effectiveness of PEG-IFN. In the setting of PEG-IFN therapy, the use of the CE model of HCV kinetics has to be reevaluated and the validity of its use depends on the amount of HCV RNA rebound observed between doses.

Modelling the kinetics of hepatitis C virus RNA decline over 4 weeks of treatment with pegylated interferon alpha-2b

Viral kinetic models for hepatitis C virus (HCV) have generally assumed that the effectiveness of therapy in blocking virion production, epsilon, is constant. However, with pegylated interferon alpha-2b (PEG-IFN) given weekly, there are significant changes in drug concentration between doses that may lead to changes in drug effectiveness and viral rebounds towards the end of the dosing interval. Here we investigate the effects of using a model that assumes a constant effectiveness for studies involving PEG-IFN. We simulated PEG-IFN treatment in a population of 294 computer simulated 'patients', each characterized by a different set of pharmacokinetic and pharmacodynamic parameters. We then sampled the simulated treatment data over 4 weeks with a schedule similar to that used in viral kinetic studies, and fitted a viral kinetic model assuming constant drug effectiveness, the CE model, to that data. Although the CE model was able to fit to the data well in most cases, the parameter estimates obtained scattered widely both above and below the true values. Thus, this model is less useful to analyse HCV RNA data during therapy with PEG-IFN than with standard IFN given daily. With PEG-IFN accurate estimation of viral dynamic parameters necessitates concomitant measurements of serum viral load and drug concentration.

A randomized study of total abdominal, vaginal and laparoscopic hysterectomy

OBJECTIVES

To evaluate operative time, blood loss and inflammatory response in patients submitted to hysterectomy.

METHODS

Sixty patients referred for hysterectomy were prospectively randomized to total abdominal hysterectomy (n=20), vaginal hysterectomy (n=20), or laparoscopic hysterectomy (n=20). The operative time, blood loss (variation in erythrocyte and hemoglobin) and inflammatory answer (CRP and interleukin-6 dosages) were compared by using Kruskal-Wallis, Dunn non-parametric test and variance analysis with repeated measurements.

RESULTS

Operative time was shorter for vaginal hysterectomy, and there was no significant difference between total abdominal hysterectomy and laparoscopic hysterectomy. Reduction in erythrocyte and hemoglobin was more noticeable after vaginal hysterectomy, followed by total abdominal hysterectomy and laparoscopic hysterectomy. CRP levels increased steadily from vaginal hysterectomy to laparoscopic hysterectomy and then to total abdominal hysterectomy. The increase in interleukin-6 was substantially higher in total abdominal hysterectomy, whereas no difference was noted between vaginal and laparoscopic hysterectomy.

CONCLUSIONS

Vaginal hysterectomy presents superior results in terms of operative time and inflammatory response when compared with total abdominal and laparoscopic hysterectomy and it should be the first option for hysterectomy. Laparoscopic hysterectomy should be considered when the vaginal approach is unfeasible, showing clear advantages over abdominal hysterectomy.

The race between initial T-helper expansion and virus growth upon HIV infection influences polyclonality of the response and viral set-point

Infection with HIV is characterized by very diverse disease-progression patterns across patients, associated with a wide variation in viral set-points. Progression is a multifactorial process, but an important role has been attributed to the HIV-specific T-cell response. To explore the conditions under which different set-points may be explained by differences in initial CD4 and CD8 T-cell responses and virus inoculum, we have formulated a model assuming that HIV-specific CD4 cells are both targets for infection and mediators of a monoclonal or polyclonal immune response. Clones differ in functional avidity for HIV epitopes. Importantly, in contrast to previous models, in this model we obtained coexistence of multiple clones at steady-state viral set-point, as seen in HIV infection. We found that, for certain parameter conditions, multiple steady states are possible: with few initial CD4 helper cells and high virus inoculum, no immune response is established and target-cell-limited infection follows, with associated high viral load; when CD4 clones are initially large and virus inoculum is low, infection can be controlled by several clones. The conditions for the dependence of viral set-point on initial inoculum and CD4 T-helper clone availability are investigated in terms of the effector mechanism of the clones involved.

Urinary tract infections in pregnant women

Urinary tract infections are of great importance during pregnancy owing to undesirable complications such as fetal and maternal morbidity. This paper describes the functional alterations that occur in this condition and predispose to infection. Clinical presentation and subsidiary diagnosis are discussed, including asymptomatic bacteriuria, cystitis and pyelonephritis. In addition, the authors report drug options, and their safety and duration of treatment during pregnancy.

Therapy of uncomplicated urinary tract infections

This article deals with many options in utilizing drugs commonly used in the therapy of uncomplicated urinary tract infections (UTIs), their doses and recommended durations of treatment. In addition, it discusses general and specific accompanying measures related to the decrease in prevalence, relapses and recurrences of UTIs, including some of the factors involved in patient adherence or discontinuation of drug regimens.

Urinary tract infections in women

Urinary tract infection (UTI) is one of the most frequent diseases in medical practice. Some definitions and epidemiology of UTI and bacteriuria are discussed, as well as host susceptibility and defense mechanisms. Aspects of infection in young women and in the elderly are reported, emphasizing microbiological, clinical and therapeutic aspects. Finally, epidemiologic and clinical aspects of fungal UTI are discussed.

Increased turnover of T lymphocytes in HIV-1 infection and its reduction by antiretroviral therapy

The mechanism of CD4(+) T cell depletion in human immunodeficiency virus (HIV)-1 infection remains controversial. Using deuterated glucose to label the DNA of proliferating cells in vivo, we studied T cell dynamics in four normal subjects and seven HIV-1-infected patients naive to antiretroviral drugs. The results were analyzed using a newly developed mathematical model to determine fractional rates of lymphocyte proliferation and death. In CD4(+) T cells, mean proliferation and death rates were elevated by 6.3- and 2.9-fold, respectively, in infected patients compared with normal controls. In CD8(+) T cells, the mean proliferation rate was 7.7-fold higher in HIV-1 infection, but the mean death rate was not significantly increased. Five of the infected patients underwent subsequent deuterated glucose labeling studies after initiating antiretroviral therapy. The lymphocyte proliferation and death rates in both CD4(+) and CD8(+) cell populations were substantially reduced by 5-11 weeks and nearly normal by one year. Taken together, these new findings strongly indicate that CD4(+) lymphocyte depletion seen in AIDS is primarily a consequence of increased cellular destruction, not decreased cellular production.

Analysis of hepatitis B viral load decline under potent therapy: complex decay profiles observed

We used a new real-time polymerase chain reaction (PCR)-based assay that is sensitive, has a wide dynamic linear range, and is highly reproducible to quantify hepatitis B virus (HBV) DNA in the serum of infected individuals undergoing potent antiviral therapy. In addition, we made frequent measurements of viral load after initiation of treatment and maintained follow-up to about 12 weeks. To analyze the data we used a new model of HBV decay, which takes into account that existing drug treatments do not completely block de novo infection and the possibility of noncytolytic loss of infected cells. On initiation of therapy, there was a mean delay of 1.6 days followed by a biphasic or muliphasic decay of plasma HBV DNA. The slope of the first phase varied considerably, with one individual having rapid decay, corresponding to a virion half-life of 1 hour, but others showing half-lives of up to 92 hours. Individuals either had a slow second-phase decline (t((1/2)) = 7.2 +/- 1.2 days) or a flat second phase. Some individuals exhibited a complex "staircase pattern" of decay, with further phases of viral DNA decline and phases with little change in viral load.

Comparison of different treatment regimens for the emergence of new resistance under therapy

OBJECTIVE

To compare the effects of different therapy regimens on the probability of emergence of new resistant mutants during therapy.

METHODS

We developed a stochastic model of infection and treatment to calculate the probability of de novo resistance during therapy. We simulated diverse treatment regimens, with different efficacy in controlling HIV replication. We studied the use of genotypic testing to choose treatment protocols specifically tailored against the wild type.

RESULTS

The probability of emergence of a previously nonexisting drug-resistant mutant during therapy depends crucially on the drug regimen used. In particular, therapy protocols targeting the wild-type strain may lead to a higher probability of treatment failure due to resistance. Conversely, targeting the minority strains in the population, which readily mutate into the resistant variety, significantly lowers the probability of a new resistant emerging under therapy.

CONCLUSIONS

Use of genotypic testing may lead to wrong decisions in the choice of therapy if the population dynamics of production of new resistant mutants is not taken into account.

Development of an evanescent-field fibre optic sensor for Escherichia coli O157:H7

An intensity-modulated fibre optic sensor was developed for Escherichia coli O157:H7. The interaction between the whole natural bacteria and the guided lightwave was carried out by means of evanescent-field coupling. A correlation between optical response and the current number of bacteria was achieved. The device sensitivity had been calibrated for initial number of bacteria (N(0)) from 10-800. The sensor sensitivity was 0.016 (+/-0.001) dB/h/N(0). The sensing mechanism starts together with the log phase leading the present sensor response to be five to ten times faster than conventional bacteriological techniques.

Production of resistant HIV mutants during antiretroviral therapy

HIV drug therapy often fails because of the appearance of multidrug-resistant virus. There are two possible scenarios for the outgrowth of multidrug-resistant virus in response to therapy. Resistant virus may preexist at low frequencies in drug-naive patients and is rapidly selected in the presence of drugs. Alternatively, resistant virus is absent at the start of therapy but is generated by residual viral replication during therapy. Currently available experimental methods are generally too insensitive to distinguish between these two scenarios. Here we use deterministic and stochastic models to investigate the origin of multidrug resistance. We quantify the probabilities that resistant mutants preexist, and that resistant mutants are generated during therapy. The models suggest that under a wide range of conditions, treatment failure is most likely caused by the preexistence of resistant mutants.

Virus phenotype switching and disease progression in HIV-1 infection

One of the phenotypic distinctions between different strains of human immunodeficiency virus type 1 (HIV-1) has to do with the ability to cause target cells to form large multinucleate bodies known as syncytia. There are two phenotypes according to this characterization: syncytium-inducing (SI) and non-syncytium-inducing (NSI). NSI strains are usually present throughout infection, while SI strains are typically seen at the beginning of the infection and near the onset of AIDS. The late emergence of SI strains is referred to as phenotype switching. In this paper we analyse the factors that lead to phenotype switching and contribute to the dynamics of disease progression. We show that a strong immune system selects for NSI strains while a weak immune system favours SI strains. The model explicitly accounts for the fact that CD4+ cells are both targets of HIV infection and crucial for activating immune responses against HIV In such a model, SI strains can emerge after a long and variable period of NSI dominated infection. Furthermore, versions of the model which do not explicitly account for HIV-specific, activated CD4+ cells do not exhibit phenotype switching, emphasizing the critical importance of this pool of cells.

All-optical control of Bragg grating in semiconductor-coated D-shaped fiber

A Bragg grating was fabricated in a D-shaped fiber that was subsequently coated with an alpha-Si:H semiconductor film. The reflected spectrum was optically controlled by means of evanescent coupling, shifting to shorter wavelengths with increased control-light power. The effective nonlinearity of the fiber was 2.0 x 10(-10) cm(2)/W . The device was optically tuned by 4.3 x 10(-4) nm/mW , leading to 54% (>3-dB) depth modulation for 230 mW of power.

A stochastic model for primary HIV infection: optimal timing of therapy

OBJECTIVE

To investigate the optimal time point for the initiation of therapy in HIV infection from the perspective of drug resistance.

BACKGROUND

The enormous genetic diversity of HIV within an infected individual represents one of the greatest challenges for effective therapy, because the viral population may harbour drug-resistant mutants that rapidly outgrow the wild-type virus once the patient starts treatment. To determine the optimal timing of therapy it is crucial to know how long it takes for the viral population to build up sufficient diversity to enable the virus to escape from therapy.

METHOD

A stochastic model of the viral diversification during primary infection was used to study the behaviour of small population sizes of mutant virus.

RESULTS AND CONCLUSIONS

The simulations suggest that from the perspective of viral diversity, therapy should be started at the viral set-point. Starting treatment earlier involves a risk of the selective outgrowth of drug-resistant mutants, which are transiently present at the viral peak during primary infection.

The frequency of resistant mutant virus before antiviral therapy

OBJECTIVE

To calculate the expected prevalence of resistant HIV mutants before antiviral therapy.

DESIGN

HIV replication generates virus mutants. The prevalence of these mutants is determined by mutation and selection/fitness. Some mutations will confer drug resistance and it is crucial for the success of antiviral drug therapy to determine whether these resistant viruses are present before the initiation of therapy.

METHODS

A quasispecies equation was used to calculate the expected frequency of drug-resistant virus prior to therapy.

RESULTS AND CONCLUSIONS

We show how the pretreatment frequency of resistant virus depends on the number of point mutations between wild-type and mutant virus, the selective disadvantage of the resistant mutant and the intermediate mutants, and the mutation rate.

Picosecond pulse shaping in a semiconductor-coated D-shaped fiber

Amorphous films of alpha-SiC:H and alpha-Si:H were deposited upon the flat surfaces of D-shaped fibers. Interaction of light with the semiconductor films occurred through evanescent coupling. Pulse shaping on a picosecond time scale was observed in 3.5-cm-long fibers with optical powers of <10 W, enhancing the effective nonlinearity by a factor of 10(3) .

The treatment of female urethral diverticulum with calculus through ultrasonic lithotripsy

A case report is presented of a large urethral diverticulum with calculus. We proposed the use of transurethral ultrasonic lithotripsy, followed by conventional surgical reconstruction 3 months later, when the condition had improved. The patient was completely cured.

[Neurological and electroencephalographic outcome in children after purulent meningoencephalitis]

Twenty children with meningitis diagnosed in the Hospital das Clinicas da Faculdade de Medicina de Ribeirão Preto between 1963 and 1967 were available for prospective study; each was submitted to neurological and electroencephalographic examination, D.Q. (Gesell) and I.Q. (Raven) tests. Patients were followed from 6 months to 3 years after the acute phase of the disease. There is statistically significant difference between the D.Q. of post-meningetic children and the D.Q. of non meningitic controls of same social class and ages, when the onset of illness was before 30 months of age. No statistically significant correlation was found between the D.Q. and the patient's length of hospitalization or the first cerebrospinal fluid protein level. There is a possibility that significant correlation between the D.Q. and age at onset of illness may be observed by studying a larger number of patients. No statistically significant difference was found between the I.Q. of post-meningitic children and controls when the onset of illness was after age 4.

[Significance of the electroencephalogram in the diagnosis of a single convulsive crisis in children]

Foram estudadas, do ponto de vista eletrencefalográfico, 20 crianças que apresentaram crise convulsiva única, com intuito de verificar se nessas condições já ocorrem alterações que possam estar relacionadas com processos orgânicos encefálicos. Considerado de maneira global, o EEG mostrou-se alterado em 13 casos (65%) e foi normal em 7 (35%); as alterações foram do tipo focal em 12 casos e difusas em um. Os eletrencefalogramas com rítmo de base irregular e disritmia paroxística registrada durante a ativação pela hiperpnéia (8 casos ou 40%) corresponderam aos pacientes que, ulteriormente, apresentaram recorrência da convulsão.