TÉCNICAS PARA AVALIAÇÃO DO EFEITO “IN VITRO” DE FUNGICIDAS SOBRE BACILLUS THURINGIENSIS VAR. KURSTAKI

RESUMO Objetivou-se comparar técnicas para a avaliação “in vitro” do efeito de fungicidas sobre Bacillus thuringiensis var. kurstaki (Btk). Foram testados os fungicidas epoxiconazole, fentin hidróxido, azoxystrobin, tebuconazole e carbendazin em duas concentrações, sobre células e esporos, em ágar nutriente (AN)-sólido (MS) e caldo nutriente (CN)-líquido (ML), além da metabolização (MT) destes por Btk. Para células em AN, os fungicidas foram testados incorporados ao meio e em discos de papel-filtro. Avaliou-se, respectivamente, as UFC/mL e a formação de halo de inibição. Para células, a mistura Bt + produtos + CN foi incubada em erlemmeyers (30 ± 2° C, 150 rpm, 24h), e em seguida, diluida e inoculada em AN, avaliandose o número de UFC/mL. Os testes de MT e esporos foram realizados em líquido (água). O efeito dos produtos variou conforme a concentração, técnica, tempo de contato e fase/estágio do desenvolvimento do patógeno. O teste ML é o mais indicado para a avaliação do efeito em células, sendo observado que a maioria dos fungicidas mostrou-se compatível com as mesmas, e apenas epoxiconazole e azoxystrobin foram metabolizados. Fentin hidróxido foi o único incompatível com esporos.

Effect of antiretroviral therapy on admissions of HIV-infected patients to an intensive care unit

OBJECTIVES

To analyse the characteristics of HIV-infected patients admitted to an Intensive Care Unit (ICU) and to compare them in the pre-highly active antiretroviral therapy (HAART) and HAART eras.

METHODS

All HIV-infected patients who were admitted to the ICU of our hospital between January 1990 and December 2003 were reviewed. Patients were divided into two groups based on whether they were admitted before or after the advent of HAART, the cut-off date being 31 December 1996.

RESULTS

Data were collected on 66 patients, 17 in the pre-HAART and 49 in the HAART era. The proportion of HIV-infected patients admitted to the ICU in our HIV-infected population increased after the introduction of HAART (3.8 vs 0.5%; P=0.001), and the largest diagnostic group was respiratory pathology in both periods. More than a third of patients were diagnosed with HIV infection during the ICU income, and only 31.2% were on antiretroviral therapy. The in-hospital mortality was 53.0%, and later survival was high. There were no significant differences between the pre-HAART and HAART eras.

CONCLUSIONS

Our results suggest that the characteristics of HIV-infected patients admitted to ICU have not changed: respiratory diseases are still the most frequent cause of admission, in-hospital mortality is high, and later survival rates are good.

Impact of highly active antiretroviral therapy on blood pressure in HIV-infected patients. A prospective study in a cohort of naive patients

OBJECTIVES

To assess the impact of highly active antiretroviral therapy (HAART) on the blood pressure (BP) of naive patients after 1 year of treatment.

METHODS

A prospective, observational study of 95 HIV-positive patients in our Unit starting HAART between January 2001 and October 2002 and maintaining the same regimen for 48 weeks of follow-up was carried out. Data on blood pressure (BP) and demographic, epidemiological, clinical, immunovirological and therapeutic characteristics related to HIV infection were collected prior to HAART and at week 48. High blood pressure (HBP) [systolic BP (SBP) > or =140 mm Hg and/or diastolic BP (DBP) > or =90 mm Hg] was defined according to international criteria.

RESULTS

Of the 95 patients, 78 were men, 44% had AIDS and 68% were smokers, and their mean age was 40 years. At week 48 the prevalence of HBP was 26% and SBP, DBP and pulse pressure (PP) increased (121.8 versus 116.6 mm Hg, P=0.0001; 76.3 versus 69.7 mm Hg, P=0.004; 46.9 versus 43.8 mm Hg, P=0.001, respectively). Univariate analysis showed that HBP was associated with older age, higher body mass index (BMI), higher baseline lipids, and higher baseline BP. A linear regression model adjusting for age and sex suggested a significant impact of older age, higher baseline SBP, higher baseline hypercholesterolaemia and lower baseline CD4-cell count on SBP increase.

CONCLUSIONS

Blood pressure increased after 48 weeks of HAART, leading to an important prevalence of hypertension. The increase in SBP depended on age and baseline lipid profile and immunological status. BP should be periodically measured and treated when necessary in HIV-infected patients on HAART.

Functional Fas (Cd95/Apo-1) promoter polymorphisms in inbred mouse strains exhibiting different susceptibility to gamma-radiation-induced thymic lymphoma

The Fas death receptor is a cell surface molecule involved in apoptosis as well as in proliferative or activating signals of many cells types, including T lymphocytes. Using quantitative real-time reverse transcription-PCR analysis, we confirm that expression of this gene is scarcely perceptible in thymic lymphomas induced by gamma-irradiation in C57BL/6J mice. Notably, we also demonstrate for the first time that Fas expression is significantly upregulated in vivo both after single high dose of radiation and in thymic lymphoma-free mice. In addition, we determined its levels of expression in five mouse strains exhibiting different degrees of susceptibility (SPRET/Ei, SEG/Pas, BALB/cJ, C57BL/6J and RF/J). Interestingly, we found the highest levels of expression in SPRET/Ei and SEG/Pas strains (both derived from the Mus spretus species), which are known to have the most resistant phenotype, and the lowest levels in the most susceptible strains C57BL/6J and RF/J. DNA sequencing of the Fas promoter in all five strains showed many polymorphisms that can be classified into three functional haplotypes by using luciferase assays: (1) C57BL/6J and RF/J, (2) BALB/cJ and (3) SPRET/Ei and SEG/Pas. Promoter activities in response to single high doses of radiation correlated well with the levels of Fas expression and are consistent with the degree of strain susceptibility.

Lack of correlation between DNA copy number and mRNA expression levels ofc-myc in γ-radiation-induced mouse thymic lymphomas by using quantitative real-time PCR

BACKGROUND

It is well documented that over-expression of the c-myc proto-oncogene occurs in the vast majority of mouse thymic lymphomas induced by gamma-irradiation, evidencing the importance of this gene in T-cell lymphomagenesis. However, it remains unknown whether elevated levels of c-myc expression are driven by extra c-myc copy numbers.

MATERIALS AND METHODS

Here we use a quantitative test on the basis of real-time PCR to determine the cellular copy number of c-myc in a set of 14 g-radiation- induced thymic lymphomas obtained from (C57BL/6J x BALB/cJ) F1 hybrid mice with increased mRNA c-myc expression.

RESULTS

Since 5 out of 14 (35.7%) cases had no extra copy numbers of c-myc, gene amplification was obviously not the cause of c-myc over-expression in these tumours. In the remaining 9 tumours, c-myc over-expression was also accompanied with extra DNA copy numbers. Therefore, c-myc amplification might be a consequence of the genomic instability subsequent to the up-regulation of c-myc. However, linear regression analysis showed a lack of correlation between increasing DNA copy numbers and mRNA over expression of c-myc in these tumours (r = 0.029, p = 0.94).

CONCLUSION

De-regulation of c-myc does not necessarily imply amplification of this gene in these tumours. This report is, to our knowledge, the first one comparing c-myc amplification with expression in lymphomas of the T-cell lineage.

Efficacy and safety of twice-daily pharmacokinetically enhanced amoxicillin/clavulanate (2000/125 mg) in the treatment of adults with community-acquired pneumonia in a country with a high prevalence of penicillin-resistant Streptococcus pneumoniae

OBJECTIVES

This randomized, double-blind, non-inferiority trial evaluated the efficacy and safety of pharmacokinetically enhanced amoxicillin/clavulanate 2000/125 mg twice daily versus amoxicillin/clavulanate 875/125 mg three times daily, both given orally for 7 or 10 days, in the treatment of adults with community-acquired pneumonia in Spain, a country with a high prevalence of penicillin-resistant Streptococcus pneumoniae.

PATIENTS AND METHODS

Following 2:1 randomization, 566 patients (intent-to-treat population) received either amoxicillin/clavulanate 2000/125 mg (n = 374) or amoxicillin/clavulanate 875/125 mg (n = 192).

RESULTS

Among the patients who did not deviate from the protocol (clinical per-protocol population), clinical success at day 21-28 post-therapy (test of cure; primary efficacy endpoint) was 92.4% (266/288) for amoxicillin/clavulanate 2000/125 mg and 91.2% (135/148) for amoxicillin/clavulanate 875/125 mg (treatment difference, 1.1; 95% confidence interval, -4.4, 6.6). Bacteriological success at test of cure in the bacteriology per-protocol population was 90.8% (79/87) with amoxicillin/clavulanate 2000/125 mg and 86.0% (43/50) with amoxicillin/clavulanate 875/125 mg (treatment difference 4.8; 95% confidence interval, -6.6, 16.2). At test of cure, amoxicillin/clavulanate 2000/125 mg was clinically and bacteriologically effective against 7/7 penicillin-resistant Streptococcus pneumoniae (MIC > or = 2 mg/L) isolates (including three amoxicillin non-susceptible strains) and amoxicillin/clavulanate 875/125 mg against 5/5 isolates (including one amoxicillin non-susceptible strain).

CONCLUSIONS

Both treatment regimens were well tolerated. Amoxicillin/clavulanate 2000/125 mg was at least as effective clinically and as safe as amoxicillin/clavulanate 875/125 mg in the treatment of community-acquired pneumonia in adults in a country with a high prevalence of penicillin-resistant S. pneumoniae and has a more convenient twice daily posology.

Modelling of acetylcholinesterase immobilized into artificial membrane

A model is developed for the investigation of an enzymatic diffusion-reaction system. The aim is to analyze the dynamic behavior of three different species, the modification of their enzymatic kinetic properties and the existence of complex behaviors resulting of the catalytic activity induced by immobilization of acetylcholinesterase into artificial membrane enzymatically inactive. We report results that make possible the characterization and prediction of complex behaviors as well as a qualitative/quantitative analysis of the system stability via bifurcation diagram which allows to study: i) the effect of the initial substrate concentration in the reservoir and ii) the effect of reaction-permeation modulus of the membrane as bifurcation parameters.

Dosimetry at the Portuguese research reactor using thermoluminescence measurements and Monte Carlo calculations

This work presents an extensive study on Monte Carlo radiation transport simulation and thermoluminescent (TL) dosimetry for characterising mixed radiation fields (neutrons and photons) occurring in nuclear reactors. The feasibility of these methods is investigated for radiation fields at various locations of the Portuguese Research Reactor (RPI). The performance of the approaches developed in this work is compared with dosimetric techniques already existing at RPI. The Monte Carlo MCNP-4C code was used for a detailed modelling of the reactor core, the fast neutron beam and the thermal column of RPI. Simulations using these models allow to reproduce the energy and spatial distributions of the neutron field very well (agreement better than 80%). In the case of the photon field, the agreement improves with decreasing intensity of the component related to fission and activation products. (7)LiF:Mg,Ti, (7)LiF:Mg,Cu,P and Al(2)O(3):Mg,Y TL detectors (TLDs) with low neutron sensitivity are able to determine photon dose and dose profiles with high spatial resolution. On the other hand, (nat)LiF:Mg,Ti TLDs with increased neutron sensitivity show a remarkable loss of sensitivity and a high supralinearity in high-intensity fields hampering their application at nuclear reactors.

Dynamical analysis of uterine cell electrical activity model

The uterus is a physiological system consisting of a large number of interacting smooth muscle cells. The uterine excitability changes remarkably with time, generally quiescent during pregnancy, the uterus exhibits forceful synchronized contractions at term leading to fetus expulsion. These changes characterize thus a dynamical system susceptible of being studied through formal mathematical tools. Multiple physiological factors are involved in the regulation process of this complex system. Our aim is to relate the physiological factors to the uterine cell dynamic behaviors. Taking into account a previous work presented, in which the electrical activity of a uterine cell is described by a set of ordinary differential equations, we analyze the impact of physiological parameters on the response of the model, and identify the main subsystems generating the complex uterine electrical activity, with respect to physiological data.

Atherogenic lipid profile and cardiovascular risk factors in HIV-infected patients (Nétar Study)

We undertook a transverse study of 603 HIV outpatients to determine their atherogenic lipid profile (ALP) and cardiovascular risk (CVR) factors. CVR was estimated from the Framingham score. ALP was defined as a total cholesterol to high density lipoprotein (HDL)-cholesterol ratio > or =5 plus triglycerides > or =150 mg/dL and a CVR >10% at 10 years was considered high. The most frequent CVR factor was smoking. ALP was diagnosed in 26.9% and was related to sex (odds ratio [OR] 2.6; 95% confidence interval [CI], 1.3-5.0; P = 0.0047), protease inhibitor use (OR 3.8; 95% CI, 1.8-7.8; P = 0.0002) and sexual HIV risk (OR 2.4; 95% CI, 1.4-4.0; P = 0.0004). The mean 10-year CVR was 6.2%, was high in 20.4% and was related to sexual HIV-risk (OR 3.8; 95% CI, 2.1-6.8; P < 0.00001) and nadir cell differentiation factor (CD4) (OR 1.0; 95% CI, 1.0-1.003; P = 0.0026). Although the current CVR of our patients is not high, the contribution to the lipid profile of highly active antiretroviral therapy (HAART)-associated factors and the high prevalence of some risk factors may lead to an increased future CVR.