HOXA9 as a key regulator in glioma initiation, aggressiveness and response to therapy

Tese de Doutoramento em Ciências da Saúde

Silver nanoparticles to fight Candida coinfection in the oral cavity

[Exert] This chapter is focused on the activity of silver nanoparticles (SN) as an antifungal agent against Candida albicans and Candida glabrata biofilms, which are involved in oral candidosis. A discussion focusing on the influence of the stabilizing agent, diameter of SN on its antibiofilm activity, influence of chemical stability of SN on Candida biofilms, the effect of SN against adhered cells and biofilms, the effect on extracellular matrix composition and structure of Candida biofilms, the combination of SN with conventional antifungal drugs, and the incorporation of SN into denture acrylic resin is incorporated in the present chapter. Because of the resistance of Candida biofilms to conventional drugs and the positive effect of SN against them, these nanoparticles can be used as an alternative antifungal agent (...).

The resistance of seeds of cowpea (Vigna unguiculata) to the cowpea weevil (Callosobruchus maculatus)

Cowpea (Vigna unguiculata) seeds are heavily damaged during storage by the bruchid Callosobruchus maculatus. Seeds of some Nigerian varieties showed a strong resistance to this bruchid. By utilizing biochemical and entomological techniques we were able to rule out the paticipation of proteolytic enzyme (trypsin, chimotrypsin, subtilisin and papain) inhibitors, lectins, and tannins in the resistance mechanisms. Fractionation of the seed meal of a resistant variety suggests that the factor(s) responsible for the effect is (are) concentrate in the globulin fraction.

Superinfection with drug-resistant HIV is rare and does not contribute substantially to therapy failure in a large European cohort.

BACKGROUND: Superinfection with drug resistant HIV strains could potentially contribute to compromised therapy in patients initially infected with drug-sensitive virus and receiving antiretroviral therapy. To investigate the importance of this potential route to drug resistance, we developed a bioinformatics pipeline to detect superinfection from routinely collected genotyping data, and assessed whether superinfection contributed to increased drug resistance in a large European cohort of viremic, drug treated patients. METHODS: We used sequence data from routine genotypic tests spanning the protease and partial reverse transcriptase regions in the Virolab and EuResist databases that collated data from five European countries. Superinfection was indicated when sequences of a patient failed to cluster together in phylogenetic trees constructed with selected sets of control sequences. A subset of the indicated cases was validated by re-sequencing pol and env regions from the original samples. RESULTS: 4425 patients had at least two sequences in the database, with a total of 13816 distinct sequence entries (of which 86% belonged to subtype B). We identified 107 patients with phylogenetic evidence for superinfection. In 14 of these cases, we analyzed newly amplified sequences from the original samples for validation purposes: only 2 cases were verified as superinfections in the repeated analyses, the other 12 cases turned out to involve sample or sequence misidentification. Resistance to drugs used at the time of strain replacement did not change in these two patients. A third case could not be validated by re-sequencing, but was supported as superinfection by an intermediate sequence with high degenerate base pair count within the time frame of strain switching. Drug resistance increased in this single patient. CONCLUSIONS: Routine genotyping data are informative for the detection of HIV superinfection; however, most cases of non-monophyletic clustering in patient phylogenies arise from sample or sequence mix-up rather than from superinfection, which emphasizes the importance of validation. Non-transient superinfection was rare in our mainly treatment experienced cohort, and we found a single case of possible transmitted drug resistance by this route. We therefore conclude that in our large cohort, superinfection with drug resistant HIV did not compromise the efficiency of antiretroviral treatment.

Voriconazole-Induced Inhibition of the Fungicidal Activity of Amphotericin B in Candida Strains with Reduced Susceptibility to Voriconazole: an Effect Not Predicted by the MIC Value Alone.

An antagonistic effect of voriconazole on the fungicidal activity of sequential doses of amphotericin B has previously been demonstrated in Candida albicans strains susceptible to voriconazole. Because treatment failure and the need to switch to other antifungals are expected to occur more often in infections that are caused by resistant strains, it was of interest to study whether the antagonistic effect was still seen in Candida strains with reduced susceptibility to voriconazole. With the hypothesis that antagonism will not occur in voriconazole-resistant strains, C. albicans strains with characterized mechanisms of resistance against voriconazole, as well as Candida glabrata and Candida krusei strains with differences in their degrees of susceptibility to voriconazole were exposed to voriconazole or amphotericin B alone, to both drugs simultaneously, or to voriconazole followed by amphotericin B in an in vitro kinetic model. Amphotericin B administered alone or simultaneously with voriconazole resulted in fungicidal activity. When amphotericin B was administered after voriconazole, its activity was reduced (median reduction, 61%; range, 9 to 94%). Levels of voriconazole-dependent inhibition of amphotericin B activity differed significantly among the strains but were not correlated with the MIC values (correlation coefficient, -0.19; P = 0.65). Inhibition was found in C. albicans strains with increases in CDR1 and CDR2 expression but not in the strain with an increase in MDR1 expression. In summary, decreased susceptibility to voriconazole does not abolish voriconazole-dependent inhibition of the fungicidal activity of amphotericin B in voriconazole-resistant Candida strains. The degree of interaction could not be predicted by the MIC value alone.

Molecular Genetic Analysis of Multi-drug Resistance in Indian Isolates of Mycobacterium tuberculosis

A total of 116 isolates from patients attending the out-patient department at the All India Institute of Medical Sciences, New Delhi and the New Delhi Tuberculosis Centre, New Delhi, India were collected. They were analyzed for resistance to drugs prescribed in the treatment for tuberculosis. The drug resistance was initially determined by microbiological techniques. The Bactec 460TB system was employed to determine the type and level of resistance in each isolate. The isolates were further characterized at molecular level. The multi-drug loci corresponding to rpo b, gyr A, kat G were studied for mutation(s) by the polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) technique. The SSCP positive samples were sequenced to characterize the mutations in rpo b, and gyr A loci. While previously reported mutations in the gyr A and rpo b loci were found to be present, several novel mutations were also scored in the rpo b locus. Interestingly, analysis of the gyr A locus showed the presence of point mutation(s) that could not be detected by PCR-SSCP. Furthermore, rifampicin resistance was found to be an important marker for checking multi-drug resistance (MDR) in clinical isolates of Mycobacterium tuberculosis. This is the first report on molecular genetic analysis of MDR tuberculosis one from India, highlights the increasing incidence of MDR in the Indian isolates of M. tuberculosis.

Drug Resistance Patterns among Hospitalized Tuberculous Patients in Rio de Janeiro, Brazil, 1993-1994

The purpose of this study was to analyze the prevalence and risk factors for drug resistance among hospitalized patients in two tertiary care centers, an acquired immunodeficiency syndrome (AIDS) reference center and a sanatorium, in Rio de Janeiro, Brazil. From 1993-1994, 389 patients were diagnosed as having tuberculosis (TB). Isolates from 265 patients were tested for in vitro susceptibility to rifampin and isoniazid. Resistance to one or more drugs was detected in 44 patients (16.6%) and was significantly more common among recurrent cases in both hospitals (p=0.03 in the AIDS center and p=0.001 in the sanatorium). Twenty seven patients (10.2%) had isolates resistant to both isoniazid and rifampin. Multi-drug resistance was associated with human immunodeficiency virus (HIV) infection among patients who had never been treated for TB. In conclusion, drug-resistant TB is high in hospitalized patients in Rio de Janeiro, especially among HIV infected patients. Therefore, measures to control TB and prevent nosocomial transmission need urgently to be set up in the Brazilian hospitals.

Resistance of Musca domestica L. populations to cyromazine (insect growth regulator) in Brazil

Five field populations of Musca domestica L. collected in poultry farms were bioassayed in order to detect possible resistance to the larvicide cyromazine in Brazil. The concentrations used were 0, 0.5, 0.1, 0.2, 0.4, 1, 2, 4 and 8 ppm. Three populations (Petrópolis, RJ, Montes Claros, MG and Promissão, SP) were resistant, while the other two populations (Ibiuna, SP and Monte Mor, SP) were more susceptible than the reference pathern used by the World Health Organization. The presence of three resistant house fly populations to cyromazine in Brazilian poultry farms strongly suggests that the operational aspects of larvicide use are important for the resistance development. Cyromazine is applied as a feed-through, both in Brazil and in the USA, where resistance has already been documented. However, in Denmark, where it was approved only as a topical manure spray, no case of resistance has yet been detected.

The effect of nitric oxide combined with fluoroquinolones against Salmonella enterica serovar Typhimurium in vitro

Two regulons, soxRS and marRAB, are associated with resistance to quinolones or multiple antibiotic in Salmonella enterica serovar Typhimurium. These regulons are activated by nitric oxide and redox-cycling drugs, such as paraquat and cause on activation of the acrAB-encoded efflux pump. In this study, we investigated the effect of nitric oxide (NO) alone and in combination with ofloxacin, ciprofloxacin, and pefloxacin against S. typhimurium clinical isolates and mutant strains in vitro. We did not observe synergistic effect against clinical isolates and SH5014 (parent strain of acr mutant), while we found synergistic effect against PP120 (soxRS mutant) and SH7616 (an acr mutant) S. typhimurium for all quinolones. Our results suggest that the efficiencies of some antibiotics, including ofloxacin, ciprofloxacin, and pefloxacin are decreased via activation of soxRS and marRAB regulons by NO in S. enterica serovar Typhimurium. Further studies are warranted to establish the interaction of NO with the genes of Salmonella and, with multiple antibiotic resistance.

Report Against Drugs- an action plan to combat substance abuse in Longford.

The Forum for Longford was started in 1997 to provide a co-ordinated inter-agency approach to identify and help tackle social problems in Longford. A survey was carried out with 1,331 post-primary students to ascertain attitudes and behaviours towards alcohol, smoking and drug use. Of the pupils interviewed, 64% had taken an alcoholic drink at age 15 or younger; of these 73% had their first drink between the ages of 12 to 15. Of those that had experience of alcohol, 51% drank several times a week or daily. For smoking, 67% had smoked a cigarette; of these 8% smoked 5 or more daily. Of those that smoked, 47% began between the ages of 11 to 14. With regard to illegal drugs 27% had used cannabis, 20% had used inhalants, 10% hallucinogens, 9% amphetamines and 7.4% had used ecstasy. Following on form these findings, the report makes several recommendations, including the formation of a community task force, Garda/ neighbourhood watch response, schools prevention and information. Also among these key areas are the role of parents, the needs of young people and facilities for young people.This resource was contributed by The National Documentation Centre on Drug Use.

Mental health and growing up factsheet. Drugs and alcohol - what parents need to know.

Information about drugs and alcohol - what parents need to know: information for parents, carers and anyone who works with young people. About this leaflet This is one in a series of leaflets for parents, teachers and young people entitled Mental Health and Growing Up. These leaflets aim to provide practical, up-to-date information about mental health problems (emotional, behavioural and psychiatric disorders) that can affect children and young people. This leaflet offers practical advice for parents, teachers and carers who are worried that a young person is misusing drugs or alcohol. Why do I need to know about a young person using drugs or alcohol? Many young people smoke, drink alcohol and may try drugs. It is important you are aware of this and do not ignore it as a time when they are just having fun or experimenting. It doesnââ,‰"¢t take much for the young people to soon lose control and to need help to recover from this problem. How common is it? By the age of 16, up to half of young people have tried an illegal drug. Young people are trying drugs earlier and more are drinking alcohol. What are the different types of drugs which cause problems? The most commonly used, readily available and strongly addictive drugs are tobacco and alcohol. There are numerous others that can be addictive. Alcohol and cannabis are sometimes seen as ââ,¬Ëogatewayââ,‰"¢ drugs that lead to the world of other drugs like cocaine and heroin. Drugs are also classed as ââ,¬Ëolegalââ,‰"¢ andââ,¬Ëoillegalââ,‰"¢. The obviously illegal drugs include cannabis (hash), speed (amphetamines), ecstasy (E), cocaine and heroin. Using ââ,¬Ëolegalââ,‰"¢ drugs (like cigarettes, alcohol, petrol, glue) does not mean they are safe or allowed to be misused. It just means they may be bought or sold for specific purposes and are limited to use by specific age groups. There are clear laws regarding alcohol and young people. For more detailed information on various drugs, their side-effects and the law, see ââ,¬ËoFurther Informationââ,‰"¢ at the end of the factsheet. Why do young people use drugs or alcohol? Young people may try or use drugs or alcohol for various reasons. They may do it for fun, because they are curious, or to be like their friends. Some are experimenting with the feeling of intoxication. Sometimes they use it to cope with difficult situations or feelings of worry and low mood. A young person is more likely to try or use drugs or alcohol if they hang out or stay with friends or family who use them. What can be the problems related to using drugs or alcohol? Drugs and alcohol can have different effects on different people. In young people especially the effects can be unpredictable and potentially dangerous. Even medications for sleep or painkillers can be addictive and harmful if not used the way they are prescribed by a doctor. Drugs and alcohol can damage health. Sharing needles or equipment can cause serious infections, such as HIV and hepatitis. Accidents, arguments and fights are more likely after drinking and drug use. Young people are more likely to engage in unprotected sex when using drugs. Using drugs can lead to serious mental illnesses, such as psychosis and depression. When does it become addiction or problem? It is very difficult to know when exactly using drugs or alcohol is more than just ââ,¬Ëocasualââ,‰"¢. Addiction becomes more obvious when the young person spends most of their time thinking about, looking for or using drugs. Drugs or alcohol then become the focus of the young personââ,‰"¢s life. They ignore their usual work, such as not doing their schoolwork, or stop doing their usual hobbies/sports such as dancing or football. How do I know if there is a problem or addiction? Occasional use can be very difficult to detect. If the young person is using on a regular basis, their behaviour often changes. Look for signs such as: ïâ?s§ unexplained moodiness ïâ?s§ behaviour that is ââ,¬Ëoout of character' ïâ?s§ loss of interest in school or friends ïâ?s§ unexplained loss of clothes or money ïâ?s§ unusual smells and items like silver foil, needle covers. Remember, the above changes can also mean other problems, such as depression, rather than using drugs. What do I do if I am worried? If you suspect young person is using drugs, remember some general rules. ïâ?s§ Pay attention to what the child is doing, including schoolwork, friends and leisure time. ïâ?s§ Learn about the effects of alcohol and drugs (see websites listed below). ïâ?s§ Listen to what the child says about alcohol and drugs, and talk about it with them. ïâ?s§ Encourage the young person to be informed and responsible about drugs and alcohol. ïâ?s§ Talk to other parents, friends or teachers about drugs - the facts and your fears and seek help. If someone in the family or close friend is using drugs or alcohol, it is important that they seek help too. It may be hard to expect the young person to give up, especially if a parent or carer is using it too. My child is abusing drugs. What do I do? ïâ?s§ If your child is using drugs or alcohol, seek help. ïâ?s§ Do stay calm and make sure of facts. ïâ?s§ Don't give up on them, get into long debates or arguments when they are drunk, stoned or high. ïâ?s§ Donââ,‰"¢t be angry or blame themââ,‰?othey need your help and trust to make journey of recovery. Where can I get help? You can talk in confidence to a professional like your GP or practice nurse, a local drug project or your local child and adolescent mental health. They can refer your child to relevant services and they will be able to offer you advice and support. You may also be able to seek help through a school nurse, teacher or social worker. You can find this information from your local area telephone book or council website, or ask for the address from your health centre. [For the full factsheet, click on the link above]This resource was contributed by The National Documentation Centre on Drug Use.

In vitro susceptibility to antifungal agents of environmental Cryptococcus spp. isolated in the city of Ribeirão Preto, São Paulo, Brazil

Infections by Cryptococcus strains other than C. neoformans have been detected in immunocompromised patients. Of these strains, three are considered human pathogens: C. albidus, C. laurenttii, and C. uniguttulatus. This study deals with the in vitro susceptibility of Cryptococcus to drugs such as amphotericin B, itraconazole, fluconazole, and 5-fluorocytosine. Environmental Cryptococcus isolates (50) distributed as follows: C. neoformans var. neoformans (16), C. albidus (17), C. laurentii (14), and C. uniguttulatus (3) were evaluated by the micro and macrodilution techniques, according to EUCAST and NCCLS recommendations, respectively. Considering both methodologies the respective minimal inhibitory concentrations (MIC) were 0.125 and 2 µg/ml for amphotericin B, 0.06 and 8 µg/ml for itraconazole, and 0.5 and more than 64 µg/ml for fluconazole and 5-fluorocytosine. Agreement percentages for the two methodologies were 100% for amphotericin B and fluconazole for all the strains tested. For itraconazole, the agreement percentage was 81.3% in the C. neoformans strain and 100% for all the others. All species had a agreement percentage of 94.1 to 100% when susceptibility to 5-fluorocytosine was tested. It is concluded that environmental isolates of C. neoformans var. neoformans, C. albidus, C. laurentii, and C. uniguttulatus may show high MICs against certain drugs, suggesting in vitro primary resistance to the antifungals tested.

Susceptibility of Colombian Plasmodium falciparum isolates to 4-aminoquinolines and the definition of amodiaquine resistance in vitro

There are wide variations in the threshold used to define in vitro resistance of Plasmodium falciparum to amodiaquine (AQ), probably due to differences in methodology and interpretation. In vitro susceptibility data of Colombian P. falciparum strains to AQ and N-desethylamodiaquine is used to illustrate the need to standardized methodologies and compare inhibitory concentrations, instead of resistant/susceptible phenotypes, when studying the mechanisms of resistance to AQ and monitoring drug susceptibility trends in the field.

Multiple refugia and barriers explain the phylogeography of the Valais shrew, Sorex antinorii (Mammalia: Soricomorpha), Sorex antinorii (Mammalia: Soricomorpha)

The aim of the present study was to investigate the genetic structure of the Valais shrew (Sorex antinorii) by a combined phylogeographical and landscape genetic approach, and thereby to infer the locations of glacial refugia and establish the influence of geographical barriers. We sequenced part of the mitochondrial cytochrome b (cyt b) gene of 179 individuals of S. antinorii sampled across the entire species' range. Six specimens attributed to S. arunchi were included in the analysis. The phylogeographical pattern was assessed by Bayesian molecular phylogenetic reconstruction, population genetic analyses, and a species distribution modelling (SDM)-based hindcasting approach. We also used landscape genetics (including isolation-by-resistance) to infer the determinants of current intra-specific genetic structure. The phylogeographical analysis revealed shallow divergence among haplotypes and no clear substructure within S. antinorii. The starlike structure of the median-joining network is consistent with population expansion from a single refugium, probably located in the Apennines. Long branches observed on the same network also suggest that another refugium may have existed in the north-eastern part of Italy. This result is consistent with SDM, which also suggests several habitable areas for S. antinorii in the Italian peninsula during the LGM. Therefore S. antinorii appears to have occupied disconnected glacial refugia in the Italian peninsula, supporting previous data for other species showing multiple refugia within southern refugial areas. By coupling genetic analyses and SDM, we were able to infer how past climatic suitability contributed to genetic divergence of populations. The genetic differentiation shown in the present study does not support the specific status of S. arunchi.

Primary resistance of human immunodeficiency virus type 1 in a reference center in Recife, Pernambuco, Brazil

To assess the prevalence of primary resistance of human immunodeficiency virus type 1 (HIV-1) to antiretrovirals, 84 patients chronically infected with HIV without prior antiretroviral treatment from Northeast Brazil were studied. Genotyping was performed using the ViroSeqTM Genotyping System. Thimidine analog mutations occurred in 3 (3.6%) patients. Accessory mutations related to NRTI occurred in 6 (7.1%) and related to PI in 67 (79.8%). Subtypes B (72.6%), F (22.6%), B/F 3 (3.6%), and C (1.2%) were detected. A low prevalence of major mutations related to NRTI in patients chronically infected by HIV was observed.