Biomedical subjects
Publications and source records attributed to F Antunes.
Melatonin has been widely reported to be an effective antioxidant. Studies of its ability to inhibit the autoxidation of lipids in homogeneous solution and in model heterogeneous systems show that melatonin is not a peroxyl radical trapping antioxidant. In contrast, melatonin can inhibit metal ion-catalyzed oxidation processes.
There are several sets of guidelines for the treatment of infective endocarditis, reflecting the need for differing treatment in various countries and times. This review considers the need for differing treatment modalities and in particular the utility of the glycopeptide antibiotics vancomycin and teicoplanin. Specific recommendations are offered as to when to consider the use of glycopeptides, appropriate dosage, length of treatment course and whether to use monotherapy or combined therapy. Used judiciously, the glycopeptides give results as good as can be achieved with other antimicrobial agents without exceptional toxicity. The potential of teicoplanin for use in the outpatient treatment of infective endocarditis is considered.
Fas, CD40L and OX40 are members of the tumour necrosis factor (TNF) receptor superfamily with critical roles in T cell activation and death, B cell function, dendritic cell maturation and leucocyte traffic regulation. The aim of this study was to evaluate the effects of anti-retroviral therapy (HAART) on CD40L, OX40 and Fas expression on freshly isolated peripheral blood T cells by three-colour flow cytometry and compare them with lymphoproliferative responses, peripheral blood cell counts and viral load. Fourteen asymptomatic HIV-1+ patients treated with Lamivudine, Stavudine and Nelfinavir were prospectively investigated sequentially for 48 weeks. At baseline, patients exhibited significantly enhanced proportions and counts of CD40L+ and OX40+ cells within the CD4 subset which were corrected by weeks 8-16 of HAART. Interestingly, in the five patients showing viral load rebound during therapy in spite of increasing CD4 counts, the reduction of the levels of these costimulatory molecules was similarly maintained. Therapy induced a decrease in the over-expression of Fas, particularly in the CD4 subset where normal levels were reached at week 8. This reduction occurred in parallel with the major recovery of lymphoproliferative responses. Higher basal levels and lower reduction of Fas were associated with suboptimal suppression of viraemia. In conclusion, this previously undescribed increased expression of CD40L and OX40 may play a role in the HIV-associated pan-immune activation and represent a possible target for immunointervention, as suggested for several immunologically mediated diseases. Moreover, HAART induced an early correction of the over-expression of Fas, CD40L and OX40 in CD4 T cells which could be involved in the recovery of the cell traffic disturbances and in the T cell renewal capacity.
A new quantitative-competitive PCR-based human immunodeficiency virus type 2 (HIV-2) proviral DNA assay (QC-PCR) was developed and used to determine the proviral load in HIV-2-infected individuals. Proviral load varied considerably, with means of 1,831 copies per 10(6) peripheral blood mononuclear cells for asymptomatic subjects (n = 19) and 2,587 for AIDS patients (n = 2). HIV-2 viral and proviral loads also varied significantly over time in asymptomatic patients. These data suggest that a high level of virus replication occurs throughout the asymptomatic phase of HIV-2 infection.
Brucellosis is a zoonosis, reported for the first time in 1859 by Marston, in Malta. It has also been referred to as Mediterranean Fever, Malta Fever and Bang's disease. Its causative agent was isolated by David Bruce in 1886; this was Brucella melitensis: five different strains were later described: B. abortus, B. suis, B. ovis, B. neotomae and B. canis. Recently, in 1994, the isolation of Brucella was reported in marine mammals, eventually pathogenic to man and unofficially designated "B. maris". Human brucellosis is still a public health problem in countries where the infection has not been eradicated from the animal hosts. When manifested, human disease may assume different courses, widely known, but whose physiopathology is still not totally clear. Much is already known about the agent's molecular biology and in vitro behaviour, but, doubts persist about its in vivo activity, including in human infection. We review some aspects of brucellosis, focusing on the pathogenesis, and referring to new and potential diagnostic methods, therapy and prevention.
OBJECTIVES: To analyse use of antiretroviral therapy within Europe between 1994 and 1997. DESIGN: From September 1994, the EuroSIDA study (cohorts I-III) has prospectively followed unselected HIV-infected patients from 50 clinical centres in 17 European countries (total, 7230). METHODS: Patients under follow-up at half-year intervals from September 1994 (n=2871) to September 1997 (n=3682) were classified according to number of drugs currently used (none, one, two, three, four or more). Use of antiretroviral therapy was stratified by CD4 cell count (< 200 versus > or = 200 x 10(6)/l) and by region of Europe (south, central, or north). Frequency data were compared by chi2 test and logistic regression modelling. RESULTS: The proportion of patients on antiretroviral monotherapy diminished over time (1994, 42%; 1997, 3%), as did the proportion of patients without therapy (from 37 to 9%). Over time, the proportion of patients on triple (from 2 to 55%) and quadruple (from 0 to 9%) therapy increased, whereas use of dual therapy peaked in 1996 and subsequently fell. In the three regions of Europe, changes in use of antiretroviral therapy differed substantially. However, as of September 1997, only minor differences persisted. The proportion of patients on dual, triple, and quadruple therapy were as follow: south, 33, 52 and 5%, respectively; central, 23, 55 and 14%, respectively; north, 16, 59 and 10%, respectively. In September 1997, odds for use of three or more drugs including at least one protease inhibitor did not differ significantly between regions. CONCLUSIONS: Use of antiretroviral therapy in Europe has changed dramatically towards combination treatment in the last few years. Regional differences in use of antiretroviral therapy have decreased, and by September 1997 only minor differences remained. Antiretroviral therapy with three or more drugs and use of protease inhibitors has become more common in all regions of Europe.
We report the findings of a longitudinal observational study on HIV-infected patients grouped by presumed transmission group, who had diarrhoea. The purpose of this study was to assess the prevalence of and factors associated with Cryptosporidium infection on these patients. Modifiied formol-ether concentration followed by modified Ziehl-Neelsen and phenol-auramine/carbol-fuchsin staining techniques were used to identify Cryptosporidium from 465 patients. Cryptosporidiosis was reported in 36/465 (8% and 95% confidence interval 6, 10) patients. Of the positive patients 30 (83%) were men and 6 (17%) women. Prevalence of infection was higher among HIV-seropositive patients whose exposure category was through sexual contact (69%) than among patients in other HIV exposure categories (9%, Standard Z test, P < 0.001). Median CD4+ cell count/mm3 was 120 (range 3-600). Besides diarrhoea, the main clinical manifestations were fever and weight loss in 14 (39%) and 26 (72%) patients, respectively. Cryptosporidium infection was considered to be the first AIDS defining disease in 31% of the patients followed by tuberculosis in 19%, Pneumocystis carinii pneumonia in 14%, Salmonella sepsis in 6%, isosporiasis in 3%, toxoplasmic encephalitis in 3%, leishmaniasis in 3% and Kaposi's sarcoma in 3% of the patients. There was no significant difference (P = 0.82) in survival times for those given folate antagonists to treat other opportunistic infections. The decrease in prevalence of cryptosporidiosis observed from 1994 until May 1997 is not statistically significant (P = 0.11). Most cases of cryptosporidial infection in AIDS patients in Lisbon occurred in those whose HIV infection was assumed to have been acquired by the sexual route (hetero-, homo- and bisexual), with few cases occurring in drug-abusers.
Phenolic antioxidants of the hydroxychroman class, alpha-tocopherol (alpha-TOC) and 2,2,5,6,7-pentamethyl-6-hydroxychroman (PMHC), and the hindered phenols 2,3-dihydro-5-hydroxy-2,2,4-trimethylnaphtho[1,2-b]furan (NFUR), 2,6-di-tert-butyl-4-methoxyphenol (DBHA), and 2,6-di-tert-butyl-4-methyl phenol (BHT), were delivered into oxidizable (ACCEPTOR) liposomes of dilinoleoylphosphatidylcholine (DLPC) or 1-palmitoyl-2-linoleoyl-phosphatidylcholine (PLPC) from saturated DONOR liposomes of dimyristoylphosphatidylcholine (DMPC) by liposomal transfer. The antioxidant activities, k(inh), by the inhibited oxygen uptake method were compared with the k(inh)s determined when the antioxidants were introduced into the liposomes by coevaporation from organic solvents. The peroxidations were initiated using either thermal initiators, water-soluble azo-bis-amidinopropane hydrochloride (ABAP), lipid-soluble azo-bis-2,4-dimethylvaleronitrile (ADVN) and di-tert-butylhyponitrite (DBHN), or the photoinitiator benzophenone. The antioxidants PMHC, NFUR, DBHA, and BHT transferred rapidly between liposomes, but several hours of incubation were needed to transfer alpha-TOC. The average k(inh)s in liposomes, in the relative order NFUR approximately DBHA > PMHC > BHT approximately alpha-TOC, were markedly lower than known values in organic solvent. k(inh) values in liposomes appear to be controlled by effects of hydrogen bonding with water and by restricted diffusion of antioxidants, especially in the case of alpha-TOC. Product studies of the hydroperoxides formed during inhibited oxygen consumption were carried out. The cis,trans/trans,trans (c,t/t,t) product ratios of the 9- and 13-hydroperoxides formed from PLPC during inhibited peroxidation by PMHC were similar for both the coevaporated and liposomal transfer procedures. The c,t/t,t ratio for the same concentration of alpha-TOC, 1.52, compares to a value of 1.69 for PMHC at the start of the inhibition period. The higher c,t/t,t ratio observed for NFUR in DLPC, which varied between values of 7.0 at the start of the inhibition to about 1.8 after the break in the induction period, is a reflection of the increased hydrogen atom donating ability of the antioxidant plus the increased concentration of oxidizable lipid provided by DLPC.
1-linoleoyl lysophosphatidylcholine hydroperoxide is a substrate of GSH peroxidase (GPx) both purified from bovine erythrocytes and nonpurified from rat liver. The initial reaction rate for bovine erythrocyte GPx with 1-linoleoyl lysophosphatidylcholine hydroperoxide is about 76 and 95% of the reaction rate for hydrogen peroxide and linoleic acid hydroperoxide respectively. For rat liver GPx these initial reaction rates are about 66 and 75%, respectively. The rate constants for the reaction of GPx with 1-linoleoyl lysophosphatidylcholine hydroperoxide were calculated to be approximately 3 x 10(7) M-1s-1 and approximately 2 x 10(6) M-1s-1 for the bovine erythrocyte and the rat liver enzymes, respectively. By using kinetic models of lipid peroxidation we found by simulation that: (1) the main source of lysophospholipid hydroperoxides in vivo is the peroxidation of lysophospholipids, both in mitochondrial inner membranes and in endoplasmic reticulum; (2) a specialized enzyme able to reduce directly lysophospholipid hydroperoxides is important for the reduction of these hydroperoxides, because the detoxification of these species mediated by the action of acyl ester bond cleaving enzymes is not efficient; (3) the reduction through GPx predominates over phospholipid hydroperoxide glutathione peroxidase (PHGPx) in mitochondrial inner membranes and in the cytosolic phase of the endoplasmic reticulum; (4) in the luminal phase of endoplasmic reticulum PHGPx is predominant.
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It has consistently been reported that older AIDS patients have a shortened survival compared with younger patients. The aim of the present study was to investigate whether this difference in survival is caused by differences in the pattern of the complicating diseases. Information on patient follow-up after the AIDS diagnosis was obtained by retrospective case note review. The 6,546 patients were followed from the time of AIDS diagnosis as part of the multicentre AIDS in Europe study, which examined AIDS cases diagnosed at 52 centres in 17 European countries between 1979 and 1989. Occurrence of AIDS-defining events and demographic variables were recorded for all patients, and CD4 lymphocyte count at the time of AIDS diagnosis for approximately half the patients. After adjusting for imbalances in other variables, persons > or = 50 years of age had a significantly higher risk of contracting AIDS wasting syndrome, AIDS dementia complex and oesophageal candidiasis after the initial AIDS diagnosis, compared with age group 30-39 years [relative risk (RR) 95% confidence interval (CI)], 3.23 (2.70-3.75 CI); 2.48 (2.16-2.80 CI); 1.55 (1.26-1.83 CI), respectively]. Shortened survival after the time of AIDS diagnosis was associated with older age. After adjusting for pattern of complicating diseases, the age effect remained unchanged. Older age predisposes to AIDS-related wasting syndrome, AIDS dementia complex and oesophageal candidiasis. Independent of these differences, older age is significantly associated with shortened survival, suggesting that factors such as severity of complicating diseases or the capability of handling serious infections, rather than disease pattern, are responsible for the shortened survival.
OBJECTIVE: To assess the safety and clinical and immunological activity of zalcitabine/zidovudine combination therapy compared with zidovudine monotherapy in persons with no or limited antiretroviral experience and CD4 counts of 300-500 cells/mm3. DESIGN AND SETTING: A double-blind controlled multi-centre study conducted in specialist human immunodeficiency virus (HIV) care centres in Spain, Portugal and Australia. Participants were randomized at study entry to zidovudine (200 mg three times daily) plus zalcitabine (0.75 mg three times daily) or matched placebo. The primary end point was the proportion of patients with CD4 above baseline value at 24 months. The secondary end points were time to AIDS/death, quality of life (by MOS-30) and safety. RESULTS: The study was terminated prematurely following the results of the Delta and ACTG 175 studies. Two-hundred and fifty-six patients entered the protocol of whom all but 15 were treatment naive. One hundred and twenty-seven patients commenced zidovudine and 129 commenced a combination of zidovudine/zalcitabine. The median duration of follow-up was 634 days with a median time on blinded therapy of 500 days. Using the last available CD4 count data, 32.4% randomized to zidovudine and 65.1% randomized to zidovudine/zalcitabine remained above baseline at study close (P < 0.001). No significant differences were observed in the time taken for CD4 count to return to baseline. Over 104 weeks, median CD4 counts rose in the combination group from 399 to 509 cells/mm3 whereas those randomized to zidovudine fell from 410 to 374 cells/mm3. Only 12 AIDS events and two deaths (both accidental) occurred during the study with no differences between groups. No differences in quality of life were observed. Adverse events were the cause of treatment discontinuation in 8.6% of patients with no differences between treatment arms. A further 8.2% of patients were lost to follow-up. At least one adverse event (all severities, all relationships) was experienced by 80.3% of patients randomized to zidovudine and 79.8% of patients on combination. Peripheral neuropathy (all grades) was reported in 10.1% of patients randomized to the combination and 3. 1% in the zidovudine arm (P = 0.026). Oral ulcers were reported in 7.8% and 4.7% of combination and zidovudine monotherapy arms, respectively. Neutropenia was more common in the zidovudine group (22%) than the combination group (14%). CONCLUSIONS: Combination of zidovudine/zalcitabine as initial therapy maintains CD4 count above commencement levels in a significantly greater proportion of patients than zidovudine monotherapy. In persons with CD4 counts > or = 300 cells/mm3 inclusion of zalcitabine with zidovudine does not increase the incidence of adverse events or adversely affect quality of life.
The aim of the study was to describe the epidemiology of AIDS dementia complex (ADC) in Europe and to assess the possible role of zidovudine therapy in preventing or delaying its occurrence. We used an inception cohort, with data collected retrospectively from patients' clinical records from 52 clinical centers in 17 countries across Europe. The subjects were 6,548 adult people with AIDS consecutively diagnosed from 1979 to 1989. The main outcome measures were codiagnosis of ADC at the time of AIDS diagnosis and ADC-free time after AIDS diagnosis. ADC was reported in 295 patients (4.5%) at the time of AIDS diagnosis and during follow-up in a further 402 of the 5,160 patients (7.8%) who were diagnosed with AIDS based on diseases other than ADC. Whether at the time of AIDS diagnosis or later, the occurrence of ADC was significantly associated with age, transmission category, and CD4+ cell counts. The risk was greater in older patients (14 and 19% greater, at AIDS diagnosis and after, respectively, for a 5-year difference in age), in i.v. drug users than in homosexual and bisexual men (89 and 60% greater, at AIDS diagnosis and after, respectively), and for people with lower CD4+ cell counts (14 and 30% greater for a reduction of 1 on the natural log scale). Risk was almost double for women than for men. A significant reduction, of approximately 40%, was found in the risk of developing ADC after AIDS diagnosis for patients receiving zidovudine therapy, but this effect was present only during the first 18 months of treatment, irrespective of whether treatment began before or after AIDS diagnosis. In conclusion, an increase in the risk of developing ADC either at the time of AIDS diagnosis or thereafter is associated with increasing age, i.v. drug use, and decreased CD4+ cell count. Women tend to have a higher risk of ADC at the time of AIDS diagnosis. Zidovudine therapy appears to have a definite, but time-limited, effect of protecting patients against ADC development after AIDS diagnosis.
An integrative mathematical model was developed to obtain an overall picture of lipid hydroperoxide metabolism in the mitochondrial inner membrane and surrounding matrix environment. The model explicitly considers an aqueous and a membrane phase, integrates a wide set of experimental data, and unsupported assumptions were minimized. The following biochemical processes were considered: the classic reactional scheme of lipid peroxidation; antioxidant and pro-oxidant effects of vitamin E; pro-oxidant effects of iron; action of phospholipase A2, glutathione-dependent peroxidases, glutathione reductase and superoxide dismutase; production of superoxide radicals by the mitochondrial respiratory chain; oxidative damage to proteins and DNA. Steady-state fluxes and concentrations as well as half-lives and mean displacements for the main metabolites were calculated. A picture of lipid hydroperoxide physiological metabolism in mitochondria in vivo showing the main pathways is presented. The main results are: (a) perhydroxyl radical is the main initiation agent of lipid peroxidation (with a flux of 10(-7)MS-1); (b) vitamin E efficiently inhibits lipid peroxidation keeping the amplification (kinetic chain length) of lipid peroxidation at low values (approximately equal to 10); (c) only a very minor fraction of lipid hydroperoxides escapes reduction via glutathione-dependent peroxidases; (d) oxidized glutathione is produced mainly from the reduction of hydrogen peroxide and not from the reduction of lipid hydroperoxides.
This study evaluated the efficacy of switching to didanosine in patients who were clinically or immunologically progressing despite zidovudine therapy. This multicenter, open-label study involved 400 patients with the acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC), who had tolerated zidovudine for at least 12 weeks and had signs of clinical or immunological disease progression. They were randomly assigned to receive 600 mg/d of zidovudine (n=133), 500 mg/d of didanosine (n=131), or 200 mg/d of didanosine (n=136). The primary end point was a new AIDS-defining event or death. The study was prematurely terminated, after the first interim analysis, mainly owing to results of two controlled studies demonstrating that a change to didanosine was associated with an improved outcome in patients with advanced HIV-1 disease. The median duration of follow-up was 53 weeks. The primary end point rates were 41, 58, and 59 (per 100 person-years) in the didanosine 500 mg, didanosine 200 mg, and zidovudine groups (zidovudine vs. didanosine 500 mg, relative risk 1.28, 95% confidence interval, 0.88-1.86, p = 0.19; didanosine 200 vs. 500 mg, relative risk 1.24, 95% confidence interval, 0.85-1.79, p = 0.26). In subjects with a baseline CD4 count of 100/mm3 or more, the primary end point rates were 8, 29, and 25 (per 100 person-years) in the didanosine 500 mg, didanosine 200 mg, and zidovudine groups, respectively (zidovudine vs. didanosine 500 mg, relative risk 2.96, 95% confidence interval 0.91-9.62, p = 0.07). No difference was seen in survival. In the didanosine 500 mg group, more patients had a 50% increase in CD4 cells (10% vs. 1% in zidovudine group, p = 0.01) and an increase of > or = 2.5 kg in body weight (2% versus 3%). Fatal pancreatitis developed in one patient assigned to didanosine 500 mg and in one to zidovudine. Our data suggest that switching from zidovudine to currently recommended doses of didanosine in subjects with ARC or AIDS who show evidence of clinical and laboratory disease progression can be associated with improvements in clinical outcome as well as in surrogate markers of HIV disease progression. This effect tended to be greater among individuals with higher CD4 counts (>100/mm3).
The comparative importance of phospholipid hydroperoxide glutathione peroxidase (PHGPx) and of "classic" glutathione peroxidase (GPx) in the reduction of phospholipid hydroperoxides is unclear. Although GPx activity is 500-fold higher than that of PHGPx in rat liver, the reduction of phospholipid hydroperoxides by glutathione (GSH) through GPx may be strongly limited by a low PLA2 activity. We address this issue using a moderately detailed kinetic model of mitochondrial lipid peroxidation in rat liver. The model was based on published data and was subjected to validation as reported in the references. It is analysed by computer simulation and sensitivity analysis. Results suggest that in rat liver mitochondria PHGPx is responsible for almost all phospholipid hydroperoxide reduction. Under physiological conditions, the estimated flux of phospholipid hydroperoxides reduction through PHGPx is about four orders of magnitude higher than the estimated hydrolysis flux through PLA2. On the other hand, virtually all hydrogen peroxide is reduced through GPx. Therefore, a functional complementarity between PHGPx and GPx is suggested. Because the results are qualitatively robust to changes of several orders of magnitude in PLA2 and PHGPx levels, the conclusions may not be limited to mitochondria.
Kinetic modelling overcomes some of the drawbacks of purely intuitive thinking in integrating information accumulated on chemical reactions involved in oxidative stress. However, it is important to assess if current knowledge about the reactions that mediate lipid peroxidation already allows satisfactory modelling of this process in near-to-physiological conditions. In this paper, a set of increasingly complex in vitro experiments on antioxidants (alpha-tocopherol and ascorbate) and lipid peroxidation in heterogeneous systems is simulated. Quantitative to semiquantitative agreement is found between experimental and simulation results. In addition, this theoretical analysis provided useful insights, suggested new hypotheses and experiments and pointed out relevant aspects needing further research. The results encourage and serve as partial validation for the formulation of relatively detailed mathematical models of in vivo lipid peroxidation. Some important aspects of the formulation and analysis of such models are discussed.
OBJECTIVES: To compare the development rate of new AIDS-defining diseases between 566 women and 1988 men with AIDS who were infected with HIV via the same routes (mainly by sharing drug injecting equipment and heterosexual sex). DESIGN: Information on patient follow-up after AIDS diagnosis was obtained by retrospectively reviewing case notes. METHODS: The 2554 men and women were followed from the time of AIDS diagnosis as part of the multicentre AIDS in Europe study, which examined AIDS cases diagnosed at 52 centres in 17 European countries between 1979 and 1989. Incidence of AIDS-defining diseases and demographic variables were recorded for all patients and CD4 lymphocyte count at the time of AIDS diagnosis for approximately half the patients. RESULTS: Only toxoplasmosis and herpes simplex virus ulceration showed statistically significant differences in occurrence rate between women and men [relative risks (RR), 1.51 and 3.44; 95% confidence interval (CI), 1.51 1.09-2.08 and 3.44 1.92-6.23, respectively] which remained after adjusting for imbalances in other variables. For both diseases, the additional absolute rate in women was approximately three per 100 person-years at risk. Survival after AIDS diagnosis was also similar between the two sexes (RR, 0.96; 95% CI, 0.86-1.08). CONCLUSION: There appears to be little difference between women and men in the clinical course of AIDS.