Activity against Plasmodium falciparum of cycloperoxide compounds obtained from the sponge Plakortis simplex

There is an urgent need to discover new antimalarials, due to the spread of chloroquine resistance and the limited number of available drugs. In the last few years, artemisinin, the endoperoxide sesquiterpene lactone derived from Artemisia annua, and its derivatives proved to be very active against Plasmodium falciparum. These compounds are characterized by an endoperoxide pharmacophore that is critical for their antimalarial activity. There are several reports, from our group and others, that marine organisms can be another natural source of stable cyclic peroxides, with selective antifungal or antibacterial activity. With the aim of identifying new bioactive molecules, we evaluated in vitro the antimalarial activity of the major cycloperoxides extracted from the sponge Plakortis simplex. The six-membered endoperoxide compounds plakortin and dihydroplakortin, but not the five-membered cycloperoxide plakortide E, inhibited the growth of cultured P. falciparum parasites, both chloroquine-sensitive D10 strain and chloroquine-resistant W2 strain. The IC50 values were similar for both compounds and in the range of 1263-1117 nM against D10, and 735-760 nM against W2, using the colorimetric parasite lactate dehydrogenase assay. The activity of plakortin and dihydroplakortin was significantly higher against chloroquine-resistant than chloroquine-susceptible parasites, following a pattern similar to that of artemisinin, although they were 50-fold less active. Moreover, plakortin and dihydroplakortin showed an additive effect when used in combination with chloroquine. These results support further studies on cycloperoxides of marine origin to characterize their mechanism of action and identify/synthesize new compounds with stronger antimalarial activity.     

Low-level resistance to rifampin in Streptococcus pneumoniae

Rifampin is recommended for combination therapy of meningitis due to beta-lactam-resistant Streptococcus pneumoniae. High-level rifampin resistance (MIC, > or =4 mg/liter) has been mapped to point mutations in clusters I and III of rpoB of the pneumococcus. The molecular basis of low-level resistance (MICs, > or =0.5 and <4 mg/liter) was analyzed. Spontaneous mutants of clinical pneumococcal isolates were selected on Columbia sheep blood agar plates containing rifampin at 0.5, 4, 10, or 50 mg/liter. Low-level resistance could be assigned to mutations in cluster II (I(545)N, I(545)L). Sensitive (MIC, <0.048 mg/liter) wild-type strains acquired low-level resistance at a rate approximately 10 times higher than that at which they acquired high-level resistance (average mutation frequencies, 2.4 x 10(-7) for low-level resistance versus 2.9 x 10(-8) for high-level resistance [P < 0.0001]). In second-step experiments, the frequencies of mutations from low- to high-level resistance were over 10 times higher than the frequencies of mutations from susceptibility to high-level resistance (average mutation frequencies, 7.2 x 10(-7) versus 5.0 x 10(-8) [P < 0.001]). Mutants with low-level resistance were stable upon passage. Sequencing of a clinical isolate with low-level resistance (MIC, 0.5 mg/liter) revealed a Q(150)R mutation upstream of cluster I. The frequencies of mutations to high-level resistance for this strain were even higher than the rates observed for the in vitro mutants. Therefore, a resistance-mediating mutation located outside clusters I, II, and III has been described for the first time in the pneumococcus. In vitro low-level rifampin resistance in S. pneumoniae could be mapped to cluster II of rpoB. Mutants of pneumococcus with low-level resistance may be selected in vivo during therapy in tissue compartments with low antibiotic concentrations and play a role in the development of resistance.     

Biocompatibility assessment of silicone oil and perfluorocarbon liquids used in retinal reattachment surgery in rat retinal cultures

The effects of silicone oil and perfluorocarbon liquids used in retinal reattachment surgery were studied in vitro using rat retinal cultures seeded on microporous inserts. These inserts allow the cell layer to be in contact with the material to be tested on the apical side and with the nutrient medium on the basal side. The materials tested were silicone oil, the perfluorocarbons perfluorophenanthrene and perfluoroctane, and hydroxypropylmethylcellulose. Perfluorophenanthrene, the heaviest of the compounds, induced a very precocious detachment of the cell layer. All the other tested biomaterials were compatible with cell survival and did not alter the structural organization of the retinal cultures, as revealed by scanning electron microscopy. By immunocytochemical techniques we evaluated the cell composition and the differentiation state of each of the cultures. In both control and treated samples, neuronal cells were well preserved. The expression of microtubule-associated protein 2, a marker of differentiated neuronal cytoskeleton, was not affected. Amacrine neurons, immunolabeled for gamma-aminobutyric acid, still were detectable after treatment. Synapses, marked by immunoreactivity for synapthophysin, were equally preserved. Vimentin-positive glial cells did not show modifications. The apoptotic rate, as determined by the terminal transferase-mediated dUTP-biotin nick end-labeling assay, was similar in treated and control samples. The results confirm that the use of biomaterials with a specific gravity close to intraocular fluids is compatible with retinal cell survival and differentiation in vitro.     

Mutations of the X-linked lymphoproliferative disease gene SH2D1A mimicking common variable immunodeficiency

Common variable immunodeficiency (CVID) and X-linked lymphoproliferative (XLP) disease are two immunodeficiencies that may share a similar immunological phenotype making differential diagnosis difficult. We report two patients initially diagnosed as affected with CVID who, using molecular analysis, have been subsequently found to be affected with XLP disease. Distinguishing between these two diseases is essential since they have different prognosis, treatment and genetic counselling. CONCLUSION: current techniques, such as genetic analysis of the SH2D1A gene and expression of signalling lymphocyte activation molecule-associated protein, allow a definite diagnosis of X-linked lymphoproliferative disease.     

Are fashion models a group at risk for eating disorders and substance abuse?

BACKGROUND: Few studies to date have investigated whether in fact the prevalence of eating disorders (ED) and/or use of illicit drugs is higher among models than among other groups of females. METHOD: A group of 63 professional fashion models of various nationalities were studied by means of self-reported questionnaires. They were compared with a control group of 126 female subjects recruited from the general population. RESULTS: Fashion models weigh significantly less than controls, but only a small percentage of them uses unhealthy methods to control their weight. The current frequency of full-syndrome ED did not differ between the groups, but partial-syndrome ED were significantly more common among fashion models than among controls. Current substance use or alcohol abuse was reported by 35% of fashion models and 12% of controls. CONCLUSION: Our findings suggest that fashion models are more at risk for partial ED and use of illicit drugs than females in the general population.     

Simple non-radiochemical HPLC-linked method for screening for purine metabolism disorders using dried blood spot

BACKGROUND: Pathologies associated with rare inherited disorders affecting purine metabolic pathways range from renal failure to neurological dysfunction and immunodeficiency. The disorders are usually diagnosed by measuring enzyme activities in hemolysates. A non-radiochemical HPLC-linked method is described for simultaneous determination of the activities of hypoxanthine-guanine phosphoribosyltransferase (HPRT: E.2.4.2.8.), adenine phosphoribosyltransferase (APRT: E.2.4.2.7.), adenosine deaminase (ADA: E.3.5.4.4.) and purine nucleoside phosphorylase (PNP: E.2.4.2.1.) in dried blood spots. METHOD: 7-mm-diameter blood spots stored at 4 degrees C or room temperature were transferred to an Eppendorf tube and eluted with 500-microl 0.1 mol/l Tris-HCl buffer, pH 7.4. The eluate was added to substrate solutions and incubated at 37 degrees C. Reaction products were analysed by HPLC. RESULTS AND CONCLUSIONS: The enzyme activities tested in spot eluates were similar to those in erythrocyte lysates from the same subjects. None of the enzymatic activities tested were significantly affected by different storage temperatures. The main advantages of the proposed method are small blood volume required, easy sample collection and transfer, and accurate results. The method is therefore suitable for screening inborn errors of purine metabolism even in newborns.     

The proportion of prostate-specific antigen (PSA) complexed to alpha(1)-antichymotrypsin improves the discrimination between prostate cancer and benign prostatic hyperplasia in men with a total PSA of 10 to 30 microg/L

BACKGROUND: The aim of this study was to assess the diagnostic accuracy of the proportion of prostate-specific antigen (PSA) complexed to alpha(1)-antichymotrypsin (PSA-alpha(1)ACT:PSA ratio) in the differential diagnosis of prostate cancer (CaP) and benign prostatic hyperplasia (BPH) in men with total PSA of 10-30 microg/L. METHODS: We used our immunoassays (ELISAs) for total PSA and PSA-alpha(1)ACT complex to study 146 men. In 123, total PSA was between 10 and 20 microg/L; 66 of these had CaP and 57 BPH. In 23 men, total PSA was between 20 and 30 microg/L; 14 of these had CaP and 9 BPH. We calculated the area under the ROC curves (AUC) for total PSA, PSA-alpha(1)ACT complex, and PSA-alpha(1)ACT:PSA ratio, and determined the cutoff points that gave sensitivities approaching 100%. RESULTS: In the total PSA range between 10 and 20 microg/L, the AUC was significantly higher for the PSA-alpha(1)ACT:PSA ratio (0.850) than for total PSA (0.507) and PSA-alpha(1)ACT complex (0.710; P <0.0001). A cutoff ratio of 0.62 would have permitted diagnosis of all 66 patients with CaP (100% sensitivity) and avoided 19% of unnecessary biopsies (11 of 57 patients). In the total PSA range between 20 and 30 microg/L, the AUC for the PSA-alpha(1)ACT:PSA ratio (0.980; 95% confidence interval, 0.82-0.99) was greater than the AUC for total PSA (0.750; 95% confidence interval, 0.51-0.89; P = 0.042). In this range, a cutoff point of 0.64 would have permitted the correct diagnosis of all 14 patients with CaP and 6 of the 9 with BPH. CONCLUSIONS: The diagnostic accuracy of the PSA-alpha(1)ACT:PSA ratio persists at high total PSA concentrations, increasing the specificity of total PSA. Prospective studies with large numbers of patients are needed to assess whether the ratio of PSA-alpha(1)ACT to total PSA is a useful tool to avoid unnecessary prostatic biopsy in patients with a total PSA >10 microg/L.