Phylogenetic placement of Cibicidoides wuellerstorfi (Schwager, 1866) from methane seeps and non-seep habitats on the Pacific margin

Benthic foraminifera are among the most abundant groups found in deep-sea habitats, including methane seep environments. Unlike many groups, no endemic foraminiferal species have been reported from methane seeps, and to our knowledge, genetic data are currently sparse for Pacific deep-sea foraminifera. In an effort to understand the relationships between seep and non-seep populations of the deep-sea foraminifera Cibicidoides wuellerstorfi, a common paleo-indicator species, specimens from methane seeps in the Pacific were analyzed and compared to one another for genetic similarities of small subunit rDNA (SSU rDNA) sequences. Pacific Ocean C. wuellerstorfi were also compared to those collected from other localities around the world (based on 18S gene available on Genbank, e.g., Schweizer et al., 2009). Results from this study revealed that C. wuellerstorfi living in seeps near Costa Rica and Hydrate Ridge are genetically similar to one another at the species level. Individuals collected from the same location that display opposite coiling directions (dextral and sinstral) had no species level genetic differences. Comparisons of specimens with genetic information available from Genbank (SSU rDNA) showed that Pacific individuals, collected for this study, are genetically similar to those previously analyzed from the North Atlantic and Antarctic. These observations provide strong evidence for the true cosmopolitan nature of C. wuellerstorfi and highlight the importance of understanding how these microscopic organisms are able to maintain sufficient genetic exchange to remain within the same species between seep and non-seep habitats and over global distances.

Development and characterization of a murine monoclonal antibody specific for the P1.15 PorA proteins from vaccine strain B:4,7:P1.19,15 of Neisseria meningitidis

Neisseria meningitidis isolates are conventionally classified by serosubtyping, which characterizes the reactivities of the PorA outer membrane protein variable-region epitopes with monoclonal antibodies (MAbs). New murine hybridomas, secreting specific MAbs against PorA of N. meningitidis serogroup B, were generated using conventional hybridoma procedures. Using outer membrane protein as antigen, we obtained two positive clones, and one of them we characterized. This MAb reacted, on whole-cell enzyme-linked immunosorbent assay (ELISA) and immunoblotting, only with strain subtype P1.15 and its IgG2b isotype. This MAb demonstrated bactericidal activity against the homologous strain in the presence of human complement.

HLA characterization in adult asymptomatic cyst passers of Entamoeba histolytica/E. dispar

The present work aimed at studying the possible association of HLA antigens with Entamoeba histolytica/E. dispar asymptomatic infection in a Mexican mestizo population. A case-control design was selected for evaluation of the role of genetic markers in parasite infection. For this purpose the HLA-A, HLA-B, and HLA-DR profiles of a population of asymptomatic E. histolytica/E. dispar adult cyst passers (cases) and a corresponding nonparasitized adult group (controls) followed for 12 months were identified. Entamoeba species were identified through zymodeme patterns and/or amplification of species-specific DNA sequences. A healthy, nonparasitized group of individuals was included as a control. Our results show that apparently, no specific HLA marker is associated with the asymptomatic cyst passers' condition. These findings have to be added to previous results in which, in contrast to a demonstrated association between HLA-DR3 and amebic liver abscess in Mexican mestizo adults and infants, no significant association with amebic rectocolitis was found.

Ecological approach of macrolide-lincosamides-streptogramin producing actinomyces from Cuban soils

We report in this study the frequency of Streptomyces strains to produce macrolide-lincosamide-streptogramin (MLS) antibiotics isolated from Cuban soils. The screening assay is based on the induction of MLS-resistance phenotype in a clinical isolated strain of Staphylococcus aureus S-18. Our results suggest that of 800 Streptomyces strains isolated from different soil samples, 6% were positives in the screening test used. The ferralitic red soil from Pinar del Río (north) provided the major percentage (3.6%) of MLS producing strains. The other soil samples tested belonging to Guira de Melena and Bauta in Havana, Matanzas City, Topes De Collantes (Villa Clara), and Soroa Mountains (Pinar del Rio) hill reached very low percentages.

Production and characterization of a monoclonal antibody against mannose-sensitive hemagglutinin of Vibrio cholerae

We have generated murine monoclonal antibodies (MAb) against Vibrio cholerae mannose-sensitive hemagglutinin (MSHA) using conventional hybridoma procedures. Seven hybridomas were obtained and one characterized. Hybridoma 2F12/F1 secreted an antibody of the IgG3 type that reacted with a 17-kDa antigen corresponding to the product of the mshA gene. This MAb inhibited mannose-sensitive agglutination of chicken erythrocytes by EL tor and O139 vibrios. Vibrios expressing MSHA activity inhibited binding of the antibody secreted by 2F12/F1 to MSHA-coated microtiter plates.

Modification of Christensen urease test as an inexpensive tool for detection of Helicobacter pylori

About half the world population is infected with Helicobacter pylori. Most live in developing countries where clinical studies face the constraints of high costs of imported rapid diagnostic tests. In this work, we describe and validate a simple local urease test (LUT) to determine the presence of the bacterium in gastric biopsies, and report the incidence of infection among symptomatic patients in Caracas, Venezuela. Statistical comparison of LUT and CLOtest (Delta West, Bentley, Australia) (N = 216 patients) showed that the probability of 95% agreement between the two test was 0.936. Overall incidence of infection determined by the LUT was 65% (N = 229), and it was higher in patients from public (72%; N = 153) than from private (50%; N = 76) hospitals (p = .001). Therefore, the incidence of infection differs in two socioeconomic groups that coexist in the same city. LUT may represent an affordable tool in clinical studies needed to identify social factors that increase the risk of infection by H. pylori.

Streptomycin blocks the afferent synapse of the isolated semicircular canals of the frog

This study aimed to define the acute electrophysiological effects of the perilymphatic perfusion of streptomycin in the sensory apparatus of the semicircular canals of the frog. The ampullary DC potential, the vestibular nerve multiunit discharge, the nerve DC potential and the unitary EPSP activity were recorded in isolated semicircular canals of the frog (Rana esculenta L). The results demonstrated that perilymphatic microperfusion of streptomycin (0.1, 0.3, 1 and 3 mM) reduced both resting and mechanically evoked afferent discharge, while the response of the hair cells remains unchanged. Intracellular recordings from single afferent axons showed that the reduction of the afferent discharge was mainly due to a reduction of the amplitude, but not the frequency, of the EPSPs. These results indicate that streptomycin, when applied in the fluid bathing the synaptic pole of the sensory cells, can act as an antagonist of the vestibular afferent transmitter at the postsynaptic level.

Streptomycin blocks the postsynaptic effects of excitatory amino acids on the vestibular system primary afferents

It has been suggested that streptomycin might be an antagonist of the glutamate receptors, and that it selectively blocks quisqualic acid receptors. We studied whether streptomycin blocks the responses to excitatory amino acid agonists on the vestibular system primary afferents, and if it allows us to differentiate between kainate (KA) and quisqualate (QA) receptor mediated responses. The experiments were performed in the axolotl (Ambystoma tigrinum). Intra- and extracellular records of the electrical activity of semicircular canal afferent fibers were obtained. Drugs were applied by pressure ejection in volumes of 20 microliters in a 10 ml bath. Streptomycin (0.01-10 mM), induced a dose dependent reversible inhibition of the basal spike discharge of the afferent fibers. This coincided with a reduction in the amplitude of excitatory postsynaptic potentials (EPSP) recorded intracellularly in the afferent fibers. Streptomycin also blocked the excitatory action produced by KA and QA; increasing concentrations of streptomycin produced a rightward shift in the concentration-response curves for both KA and QA. This action persisted even in a high Mg2+ (10 mM), low Ca2+ (0.09 mM) Ringer solution, indicating its postsynaptic nature. These results show that streptomycin might be a non-selective excitatory amino acid (EAA) receptor antagonist.

[Evaluation of transcutaneous oxygen pressure in adults with respiratory pathology]

The usefulness of the transcutaneous oxygen tension (tcPO2) in adults is under controversy. In a varied group of respiratory patients, results of the application of this method were compared with those from the arterial blood sampling method. Thirty-eight arterial oxygen tension (PaO2) and tcPO2 simultaneous determinations were made in a group of 22 patients, while in a sitting position; the tcPO2 measurements obtained (68 +/- 12.36 Torr) were significantly lower (p less than 0.05) than the PaO2 values (74 +/- 13.07 Torr). The correlation coefficient was 0.51 (p less than 0.01) with a regression line, tcPO2 = 31.58 + 0.48 PaO2. It is concluded that tcPO2 measurement does not correlate well with PaO2 and that this method cannot be always be safely applied and used in adults with respiratory diseases.