A new species of Dichelyne (Nematoda: Cucullanidae) parasitizing Acanthistius brasilianus (Pisces: Serranidae) from Argentinean waters

During a parasitological examination of 45 specimens of Acanthisthius brasilianus (Valenciennes, 1828) Jordan et Eigenmann, 1890, from waters off Mar del Plata, Argentina (38 degrees 08'S, 57 degrees 32'W), several specimens of cucullanid nematodes were collected from the intestines. A new species, Dichelyne (Cucullanellus) szidati n. sp., is described (prevalence 42.2%, mean intensity 2.7). The new species differs from its congeners inhabiting the southwestern Atlantic by the distribution pattern of caudal papillae, particularly the ninth pair, length of the body and spicules, and the position of the intestinal cecum (ventral), the excretory pore (posterior to esophagus), and the deirids (at the level of esophageal posterior end).     

VSV transmembrane domain (TMD) peptide promotes PEG-mediated fusion of liposomes in a conformationally sensitive fashion

Helical instability induced by gly residues in the transmembrane domain (TMD) of G protein, the fusion protein of vesicular stomatitis virus (VSV), was speculated to aid in the later steps of the fusion process, because G protein with ala's substituted for the two TMD gly's was inactive (Cleverley, D. Z., and Lenard, J. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 3425-30). Here we examine the conformations of synthetic peptides corresponding to fusion-active (GGpep) and inactive (AApep; G's replaced by A's) TMDs by CD spectroscopy, and then their effects on the kinetics of poly (ethyleneglycol) (PEG)-mediated fusion of small unilamellar vesicles. GGpep and AApep both assumed history-dependent, non-interconvertible ordered structures. Both peptides were largely helical under all conditions if derived from trifluoroethanol solutions, and aggregated in a beta-sheet form if derived from acetonitrile solutions. In solvent, detergents or lipid bilayers, GGpep showed a greater range of secondary structural features than did AApep. The two peptides had large but different effects on PEG-mediated fusion. Both enhanced the rate but not the extent of lipid mixing. AApep significantly inhibited the extent of fusion pore formation while GGpep had no effect. The initial rate of fusion was enhanced 6-fold by GGpep and less than 2-fold by AApep. Addition of 5 mol % hexadecane overrode all peptide-induced effects. We suggest that both GGpep and hexadecane promote pore formation by stabilizing the nonlamellar structures in fusion intermediates or initial small pores. AApep, which had fewer nonhelical features in its CD spectrum than GGpep, actually inhibited fusion pore formation.     

Phospholipase C inhibitors and prostaglandins differentially regulate phosphatidylcholine synthesis in rat renal papilla. Evidence of compartmental regulation of CTP:phosphocholine cytidylyltransferase and CDP-choline:1,2-diacylglycerol cholinephosphotransferase

Phosphatidylcholine (PC) is the most abundant phospholipid in mammalian cell membranes. Several lines of evidence support that PC homeostasis is preserved by the equilibrium between PC biosynthetic enzymes and phospholipases catabolic activities. We have previously shown that papillary synthesis of PC depends on prostaglandins (PGs) that modulate biosynthetic enzymes. In papillary tissue, under bradikynin stimulus, arachidonic acid (AA) mobilization (the substrate for PG synthesis) requires a previous phospholipase C (PLC) activation. Thus, in the present work, we study the possible involvement of PLC in PC biosynthesis and its relationship with PG biosynthetic pathway on the maintenance of phospholipid renewal in papillary membranes; we also evaluated the relevance of CDP-choline pathway enzymes compartmentalization. To this end, neomycin, U-73122 and dibutiryl cyclic AMP, reported as PLC inhibitors, were used to study PC synthesis in rat renal papilla. All the PLC inhibitors assayed impaired PC synthesis. PG synthesis was also blocked by PLC inhibitors without affecting cyclooxygenase activity, indicating a metabolic connection between both pathways. However, we found that PC biosynthesis decrease in the presence of PLC inhibitors was not a consequence of PG decreased synthesis, suggesting that basal PLC activity and PGs exert their effect on different targets of PC biosynthetic pathway. The study of PC biosynthetic enzymes showed that PLC inhibitors affect CTP:phosphocholine cytidylyltransferase (CCT) activity while PGD(2) operates on CDP-choline:1,2-diacylglycerol cholinephosphotransferase (CPT), both activities associated to papillary enriched-nuclei fraction. The present results suggest that renal papillary PC synthesis is a highly regulated process under basal conditions. Such regulation might occur at least at two different levels of the CDP-choline pathway: on the one hand, PLC operates on CCT activity; on the other, while PGs regulate CPT activity.     

Stress proteins of<Emphasis Type="Italic"> Clostridium perfringens</Emphasis> type A immunoreact with antiserum from rabbits infected with gas gangrene

Various stressors were used to induce stress proteins in Clostridium perfringens. Cultures of C. perfringens FD-1041 were subjected to cold shock (28°C for 1 h), acid shock (pH 4.5 for 30 min), or heat shock (50°C for 30 min). Cells were lysed and protein samples were analyzed by immunoblotting with antiserum derived from rabbits suffering from gas gangrene. Eight cold shock proteins (approximate M_r 101, 82, 70, 37, 22, 12, 10 and 6 kDa) and also eight heat shock proteins (approximate M_r 101, 82, 70, 27, 22, 16, 12 and 10 kDa) were immunoreactive with the serum. No immunoreactive proteins were detected in samples subjected to acid shock proteins and purified DnaK protein was also non-immunoreactive with the serum. These immunogenic stress proteins may be important in regulating diseases caused by C. perfringens. Such proteins could be involved in cell survival mechanisms, serve as targets during infection, or play a role in recognition of the bacteria by the host.     

Fimbriae and adherence of Stenotrophomonas maltophilia to epithelial cells and to abiotic surfaces

Stenotrophomonas maltophilia is an emerging nosocomial bacterial pathogen associated with several infectious diseases and opportunistic infections, especially in immunocompromised patients. These bacteria adhere avidly to medical implants and catheters forming a biofilm that confers natural protection against host immune defences and different antimicrobial agents. The nature of the bacterial surface factors involved in biofilm formation on inert surfaces and in adherence of S. maltophilia to epithelial cells is largely unknown. In this study, we identified and characterized fimbrial structures produced by S. maltophilia grown at 37 degrees C. The S. maltophilia fimbriae 1 (SMF-1) are composed of a 17 kDa fimbrin subunit which shares significant similarities with the N-terminal amino acid sequences of several fimbrial adhesins (G, F17, K99 and 20K) found in Escherichia coli pathogenic strains and the CupA fimbriae of Pseudomonas aeruginosa. All of the clinical S. maltophilia isolates tested produced the 17 kDa fimbrin. Antibodies raised against SMF-1 fimbriae inhibited the agglutination of animal erythrocytes, adherence to HEp-2 cells and biofilm formation by S. maltophilia. High resolution electron microscopy provided evidence of the presence of fimbriae acting as bridges between bacteria adhering to inert surfaces or to cultured epithelial cells. This is the first characterization of fimbriae in this genus. We provide compelling data suggesting that the SMF-1 fimbriae are involved in haemagglutination, biofilm formation and adherence to cultured mammalian cells.     

Vertical versus Wise pattern breast reduction: patient satisfaction, revision rates, and complications

A prospective, randomized study was designed to compare the outcome of inferior pedicle/Wise pattern reduction (group I) with medial pedicle/vertical pattern reduction (group II) in moderate resections averaging 500 g per breast. There were 105 women in group I and 103 women in group II. All surgical procedures were performed by the same plastic surgeon. Patient information recorded included age, body mass index, type of surgery, weight of specimen, need for surgical revision, and complications. Six months postoperatively the patients were asked to complete a questionnaire, which rated their satisfaction with the surgical outcome. The questionnaire used a 10-point response format ranging from very disappointed (score of 1) to very pleased (score of 10). The results demonstrated that there was no significant difference between the groups in age (31 +/- 12 versus 29 +/- 13 years), body mass index (26 +/- 4 versus 27 +/- 5), and amount of tissue excised (553 +/- 203 g versus 548 +/- 205 g). Group I required no surgical revisions, but in group II revisions for dog-ears were required in 11 percent. The rate of other complications was similar in both groups. Patients' evaluations of breast size, shape, symmetry, nipple sensation, symptom relief, ease of brassiere/clothing fitting, and overall satisfaction were not significantly different. The vertical mammaplasty was ranked significantly (p < 0.05) higher by patients in regard to scars (6 +/- 2 versus 3 +/- 3) and overall aesthetic results (8 +/- 1 versus 6 +/- 3). In the management of moderate macromastia, this study indicates that patients who have a vertical reduction are less disappointed with the scars but require a significantly higher rate of surgical revisions compared with patients who have a Wise pattern reduction.     

Prevalence of cagA and vacA genes in isolates from patients with Helicobacter pylori-associated gastroduodenal diseases in Recife, Pernambuco, Brazil

Geographical differences in the prevalence of Helicobacter pylori genes and their association with disease severity have been identified. This study analyzes the prevalences of the cagA gene and alleles of the vacA gene in H. pylori-associated gastroduodenal diseases in isolates from Recife, PE, Brazil. Gastric biopsy of 61 H. pylori-positive patients were submitted to DNA extraction and gene amplification by polymerase chain reaction. Among the 61 patients, 21 suffered from duodenal ulcer (DU) and 40 from gastritis (GT). The prevalence of H. pylori strains harbouring the cagA gene was higher in the DU group (90.5%) than in the GT group (60%) (p=0.02). The vacA gene was amplified in 56 out of 61 biopsies, of which 43 (76.8%) contained bacteria carrying the s1 allele and 13 (23.2%) the s2. However, the prevalence of the vacA s1 genotyping was the same in either DU or GT group. The majority of the s1-typed strains, 39 (90.7%) out of 43, were subtype s1b. In resume there was a strong association between the H. pylori cagA+ gene and DU. However, there were no differences between the DU and GT groups in relation to the vacA s1 and s2 alleles distribution, albeit the subtype s1b was predominant.     

High-performance thin-layer chromatography-bioautography for multiple antibiotic residues in cow's milk

An analytical method to identify and quantify multiple antibiotic residues (chloramphenicol, ampicillin, benzylpenicillin, dicloxacillin and erythromycin) in cow's milk by high-performance thin-layer chromatography (HPTLC) combined with bioautography was developed. The test microorganism used for bioautography was Bacillus subtilis ATCC 6633. Antibiotic residues were extracted with acetonitrile, fat eliminated with petroleum ether and residues isolated with dichloromethane The sensitivity of the method guarantees the detection of the above-mentioned antibiotics at levels below maximum residue limits (MRL) allowed for milk. Percentage recoveries ranged between 90 and 100%, with coefficients of variation between 7.2 and 21.3%. Some advantages of this methodology over thin-layer chromatography (TLC)/bioautography are also discussed.     

Phosphorylation of LHI β During Membrane Synthesis in the Photosynthetic Bacterium Rhodovulum sulfidophilum

Cells of Rhv. sulfidophilum were grown under different conditions in the presence of ³²P-phosphate and the corresponding H and L membrane fractions obtained and fractionated by SDS-PAGE. Both membranes showed almost identical polypeptide composition. The bacteriochlorophyll (Bchl) specific content in H was always lower that in L. As described before, oxygen did not regulate gene expression. Under high light, an almost two- to threefold decrease of the cellular specific Bchl content was observed. Pulse and chase experiments showed that transitions from aerobiosis to light-anaerobiosis did not quantitatively affect the Bchl content of the membranes, although a turnover of the ³²P-phosphate and ³⁵S-methionine was observed. LHI β was the only polypeptidic subunit of the Bchl-binding polypeptides that was phosphorylated in vivo, and phosphotyrosine was the only phosphorylated amino acid detectable. The phosphorylated LHI β was determined to be insoluble in the organic solvent mixture of (vol/vol) 1:1 chloroform-methanol containing ammonium acetate (0.1 m final concentration). Treatment with a chaotropic agent such as Na₂CO₃ solubilized the phosphorylated LHI β, indicating that part of this posttranslationally modified polypeptide was not inserted in a transmembrane position. These results were used to speculate about the regulatory properties of this posttranslational modification of LHI β on membrane differentiation. Received: 30 August 2000 / Accepted: 2 October 2000